{"id": "0708.1996", "abstract": "  We study the phase behavior of a nematic liquid crystal confined between a flat substrate with strong anchoring and a patterned substrate whose structure and local anchoring strength we vary. By first evaluating an effective surface free energy function characterizing the patterned substrate we derive an expression for the effective free energy of the confined nematic liquid crystal. Then we determine phase diagrams involving a homogeneous state in which the nematic director is almost uniform and a hybrid aligned nematic state in which the orientation of the director varies through the cell. Direct minimization of the free energy functional were performed in order to test the predictions of the effective free energy method. We find remarkably good agreement between the phase boundaries calculated from the two approaches. In addition the effective energy method allows one to determine the energy barriers between two states in a bistable nematic device. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0708/0708.1996v1.pdf"}
{"id": "1004.4550", "abstract": "  We study a holomorphic representation for spinfoams. The representation is obtained via the Ashtekar-Lewandowski-Marolf-Mourão-Thiemann coherent state transform. We derive the expression of the 4d spinfoam vertex for Euclidean and for Lorentzian gravity in the holomorphic representation. The advantage of this representation rests on the fact that the variables used have a clear interpretation in terms of a classical intrinsic and extrinsic geometry of space. We show how the peakedness on the extrinsic geometry selects a single exponential of the Regge action in the semiclassical large-scale asymptotics of the spinfoam vertex. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.4550v3.pdf"}
{"id": "1012.5771", "abstract": "  Class I methanol masers are believed to be produced in the shock-excited environment around star-forming regions. Many authors have argued that the appearance of various subsets of class I masers may be indicative of specific evolutionary stages of star formation or excitation conditions. Until recently, however, no major interferometer was capable of imaging the important 36 GHz transition. We report on Expanded Very Large Array observations of the 36 GHz methanol masers and Submillimeter Array observations of the 229 GHz methanol masers in DR21(OH), DR21N, and DR21W. The distribution of 36 GHz masers in the outflow of DR21(OH) is similar to that of the other class I methanol transitions, with numerous multitransition spatial overlaps. At the site of the main continuum source in DR21(OH), class I masers at 36 and 229 GHz are found in virtual overlap with class II 6.7 GHz masers. To the south of the outflow, the 36 GHz masers are scattered over a large region but usually do not appear coincident with 44 GHz masers. In DR21W we detect an \"S-curve\" signature in Stokes V that implies a large value of the magnetic field strength if interpreted as due to Zeeman splitting, suggesting either that class I masers may exist at higher densities than previously believed or that the direct Zeeman interpretation of S-curve Stokes V profiles in class I masers may be incorrect. We find a diverse variety of different maser phenomena in these sources, suggestive of differing physical conditions among them. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.5771v1.pdf"}
{"id": "1112.4795", "abstract": "  We show how to control spatial quantum correlations in a multimode degenerate optical parametric oscillator type I below threshold by introducing a spatially inhomogeneous medium, such as a photonic crystal, in the plane perpendicular to light propagation. We obtain the analytical expressions for all the correlations in terms of the relevant parameters of the problem and study the number of photons, entanglement, squeezing, and twin beams. Considering different regimes and configurations we show the possibility to tune the instability thresholds as well as the quantumness of correlations by breaking the translational invariance of the system through a photonic crystal modulation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.4795v1.pdf"}
{"id": "1601.06075", "abstract": "  Nowadays, scientific challenges usually require approaches that cross traditional boundaries between academic disciplines, driving many researchers towards interdisciplinarity. Despite its obvious importance, there is a lack of studies on how to quantify the influence of interdisciplinarity on the research impact, posing uncertainty in a proper evaluation for hiring and funding purposes. Here we propose a method based on the analysis of bipartite interconnected multilayer networks of citations and disciplines, to assess scholars, institutions and countries interdisciplinary importance. Using data about physics publications and US patents, we show that our method allows to reward, using a quantitative approach, scholars and institutions that have carried out interdisciplinary work and have had an impact in different scientific areas. The proposed method could be used by funding agencies, universities and scientific policy decision makers for hiring and funding purposes, and to complement existing methods to rank universities and countries. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.06075v2.pdf"}
{"id": "astro-ph9702020", "abstract": "  Two questions that naturally arise in N-body simulations of stellar systems are: (1) How can we compare experiments that employ different types of softened gravity? (2) Given a particular type of softened gravity, which choices of the softening length optimize the faithfulness of the experiments to the Newtonian dynamics? We devise a method for exploring the dynamical effects of softening, which provides detailed answers in the case of 2-D simulations of disc galaxies and also solves important aspects of the 3-D problem. In the present paper we focus on two applications that reveal the dynamical differences between the most representative types of softened gravity, including certain anisotropic alternatives. Our method is potentially important not only for testing but also for developing new ideas about softening. Indeed, it opens a direct route to the discovery of optimal types of softened gravity for given dynamical requirements, and thus to the accomplishment of a physically consistent modelling. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9702/9702020v1.pdf"}
{"id": "cond-mat0301405", "abstract": "  We present a theoretical study of the infrared magneto-optical properties of ferromagnetic (III,Mn)V semiconductors. Our analysis combines the kinetic exchange model for (III,Mn)V ferromagnetism with Kubo linear response theory and Born approximation estimates for the effect of disorder on the valence band quasiparticles. We predict a prominent feature in the ac-Hall conductivity at a frequency that varies over the range from 200 to 400 meV, depending on Mn and carrier densities, and is associated with transitions between heavy-hole and light-hole bands. In its zero frequency limit, our Hall conductivity reduces to the k⃗-space Berry's phase value predicted by a recent theory of the anomalous Hall effect that is able to account quantitatively for experiment. We compute theoretical estimates for magnetic circular dichroism, Faraday rotation, and Kerr effect parameters as a function of Mn concentration and free carrier density. The mid-infrared response feature is present in each of these magneto-optical effects. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0301/0301405v1.pdf"}
{"id": "physics0410012", "abstract": "  We consider evaluation of matrix elements with the coupled-cluster method. Such calculations formally involve infinite number of terms and we devise a method of partial summation (dressing) of the resulting series. Our formalism is built upon an expansion of the product C^† C of cluster amplitudes C into a sum of n-body insertions. We consider two types of insertions: particle/hole line insertion and two-particle/two-hole random-phase-approximation-like insertion. We demonstrate how to “dress” these insertions and formulate iterative equations. We illustrate the dressing equations in the case when the cluster operator is truncated at single and double excitations. Using univalent systems as an example, we upgrade coupled-cluster diagrams for matrix elements with the dressed insertions and highlight a relation to pertinent fourth-order diagrams. We illustrate our formalism with relativistic calculations of hyperfine constant A(6s) and 6s_1/2-6p_1/2 electric-dipole transition amplitude for Cs atom. Finally, we augment the truncated coupled-cluster calculations with otherwise omitted fourth-order diagrams. The resulting analysis for Cs is complete through the fourth-order of many-body perturbation theory and reveals an important role of triple and disconnected quadruple excitations. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0410/0410012v1.pdf"}
{"id": "0704.1144", "abstract": "  Gradient networks can be used to model the dominant structure of complex networks. Previous works have focused on random gradient networks. Here we study gradient networks that minimize jamming on substrate networks with scale-free and Erdős-Rényi structure. We introduce structural correlations and strongly reduce congestion occurring on the network by using a Monte Carlo optimization scheme. This optimization alters the degree distribution and other structural properties of the resulting gradient networks. These results are expected to be relevant for transport and other dynamical processes in real network systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.1144v1.pdf"}
{"id": "0704.2719", "abstract": "  Only the 1/V_max method has been employed so far for observationally determining the white dwarf luminosity function, whereas for other kind of luminosity functions several other methods have been frequently used. Moreover, the procedures to determine the white dwarf luminosity function are not free of biases. These biases have two different origins: they can either be of statistical nature or a consequence of the measurement errors. In a previous paper we carried out an in-depth study of the first category of biases for several luminosity function estimators. In this paper we focus on the biases introduced by the measurement errors and on the effects of the degree of contamination of the input sample used to build the disc white dwarf luminosity function by different kinematical populations. To assess the extent of these biases we use a Monte Carlo simulator to generate a controlled synthetic population and analyse the behaviour of the disc white dwarf luminosity function for several assumptions about the magnitude of the measurement errors and for several degrees of contamination, comparing the performances of the most robust luminosity function estimators under such conditions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.2719v1.pdf"}
{"id": "0704.2855", "abstract": "  The generator coordinate (GC) method is a variational approach to the quantum many-body problem in which interacting many-body wave functions are constructed as superpositions of (generally nonorthogonal) eigenstates of auxiliary Hamiltonians containing a deformation parameter. This paper presents a time-dependent extension of the GC method as a new approach to improve existing approximations of the exchange-correlation (XC) potential in time-dependent density-functional theory (TDDFT). The time-dependent GC method is shown to be a conceptually and computationally simple tool to build memory effects into any existing adiabatic XC potential. As an illustration, the method is applied to driven parametric oscillations of two interacting electrons in a harmonic potential (Hooke's atom). It is demonstrated that a proper choice of time-dependent generator coordinates in conjunction with the adiabatic local-density approximation reproduces the exact linear and nonlinear two-electron dynamics quite accurately, including features associated with double excitations that cannot be captured by TDDFT in the adiabatic approximation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.2855v1.pdf"}
{"id": "0705.0485", "abstract": "  A comparative study between two distinct perturbative series expansions for the pair-creation contact process is presented. In contrast to the ordinary contact process, whose supercritical series expansions provide accurate estimates for its critical behavior, the supercritical approach does not work properly when applied to the pair-creation process. To circumvent this problem a procedure is introduced in which one-site creation is added to the pair-creation. An alternative method is the generation of subcritical series expansions which works even for the case of the pure pair-creation process. Differently from the supercritical case, the subcritical series yields estimates that are compatible with numerical simulations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.0485v1.pdf"}
{"id": "0705.3995", "abstract": "  In this paper, an analysis of the undetected error probability of ensembles of binary matrices is presented. The ensemble called the Bernoulli ensemble whose members are considered as matrices generated from i.i.d. Bernoulli source is mainly considered here. The main contributions of this work are (i) derivation of the error exponent of the average undetected error probability and (ii) closed form expressions for the variance of the undetected error probability. It is shown that the behavior of the exponent for a sparse ensemble is somewhat different from that for a dense ensemble. Furthermore, as a byproduct of the proof of the variance formula, simple covariance formula of the weight distribution is derived. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.3995v2.pdf"}
{"id": "0705.4241", "abstract": "  We observe a complex change in the hopping exponent value from 1/2 to 1/3 as a function of disorder strength and electron density in a sodium-doped silicon MOSFET. The disorder was varied by applying a gate voltage and thermally drifting the ions to different positions in the oxide. The same gate was then used at low temperature to modify the carrier concentration. Magnetoconductivity measurements are compatible with a change in transport mechanisms when either the disorder or the electron density is modified suggesting a possible transition from a Mott insulator to an Anderson insulator in these systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.4241v10.pdf"}
{"id": "0706.0168", "abstract": "  We show that the Kullback-Leibler distance is a good measure of the statistical uncertainty of correlation matrices estimated by using a finite set of data. For correlation matrices of multivariate Gaussian variables we analytically determine the expected values of the Kullback-Leibler distance of a sample correlation matrix from a reference model and we show that the expected values are known also when the specific model is unknown. We propose to make use of the Kullback-Leibler distance to estimate the information extracted from a correlation matrix by correlation filtering procedures. We also show how to use this distance to measure the stability of filtering procedures with respect to statistical uncertainty. We explain the effectiveness of our method by comparing four filtering procedures, two of them being based on spectral analysis and the other two on hierarchical clustering. We compare these techniques as applied both to simulations of factor models and empirical data. We investigate the ability of these filtering procedures in recovering the correlation matrix of models from simulations. We discuss such an ability in terms of both the heterogeneity of model parameters and the length of data series. We also show that the two spectral techniques are typically more informative about the sample correlation matrix than techniques based on hierarchical clustering, whereas the latter are more stable with respect to statistical uncertainty. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0706/0706.0168v1.pdf"}
{"id": "0706.1279", "abstract": "  We summarize the status of Modified Newtonian Dynamics (MOND) in galaxy clusters. The observed acceleration is typically larger than the acceleration threshold of MOND in the central regions, implying that some dark matter is necessary to explain the mass discrepancy there. A plausible resolution of this issue is that the unseen mass in MOND is in the form of ordinary neutrinos with masses just below the experimentally detectable limit. In particular, we show that the lensing mass reconstructions of the clusters 1E0657-56 (the bullet cluster) and Cl0024+17 (the ring) do not pose a new challenge to this scenario. However, the mass discrepancy for cool X-ray emitting groups, in which neutrinos cannot cluster, pose a more serious problem, meaning that dark baryons could present a more satisfactory solution to the problem of unseen mass in MOND clusters. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0706/0706.1279v2.pdf"}
{"id": "0706.3201", "abstract": "  We consider the cosmological dynamics associated with volume weighted measures of eternal inflation, in the Bousso-Polchinski model of the string theory landscape. We find that this measure predicts that observers are most likely to find themselves in low energy vacua with one flux considerably larger than the rest. Furthermore, it allows for a satisfactory anthropic explanation of the cosmological constant problem by producing a smooth, and approximately constant, distribution of potentially observable values of Lambda. The low energy vacua selected by this measure are often short lived. If we require anthropically acceptable vacua to have a minimum life-time of 10 billion years, then for reasonable parameters a typical observer should expect their vacuum to have a life-time of approximately 12 billion years. This prediction is model dependent, but may point toward a solution to the coincidence problem of cosmology. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0706/0706.3201v1.pdf"}
{"id": "0707.0820", "abstract": "  Detailed far-infrared spectra of the optical phonons are reported for antiferromagnetic MnO. Eigenfrequencies, phonon damping and effective plasma frequencies are studied as a function of temperature. Special attention is paid to the phonon splitting at the antiferromagnetic phase transition. The results are compared to recent experimental and theoretical studies of the spin-phonon coupling in frustrated magnets, which are explained in terms of a spin-driven Jahn-Teller effect, and to ab initio and model calculations, which predict phonon splitting induced by magnetic order. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0707/0707.0820v2.pdf"}
{"id": "0707.2418", "abstract": "  We present an observation of XMM-Newton that unambiguously reveals the “Seyfert 2” nature of the Broad Line Radio Galaxy 3C 445. For the first time the soft excess of this source has been resolved. It consists of unobscured scattered continuum flux and emission lines, likely produced in a warm photoionized gas near the pole of an obscuring torus. The presence of circumnuclear (likely stratified) matter is supported by the complex obscuration of the nuclear region. Seventy percent of the nuclear radiation (first component) is indeed obscured by a column density  4*10^23 cm^-2, and 30 ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0707/0707.2418v1.pdf"}
{"id": "0708.1119", "abstract": "  A spiral galaxy partially ovelapping a more distant elliptical offers an unique opportunity to measure the dust extinction in the foreground spiral.   From the Sloan Digital Sky Survey DR4 spectroscopic sample, we selected 83 occulting galaxy pairs and measured disk opacity over the redshift range z = 0.0-0.2 with the goal to determine the recent evolution of disk dust opacity. The enrichment of the ISM changes over the lifetime of a disk and it is reasonable to expect the dust extinction properties of spiral disks as a whole to change over their lifetime. When they do, the change will affect our measurements of galaxies over the observable universe.   From the SDSS pairs we conclude that spiral disks show evidence of extinction to  2 effective radii. However, no evidence for recent evolution of disk opacity is evident, due to the limited redshift range and our inability to distinguish other factors on disk opacity such as the presence of spiral arms and Hubble type. Such effects also mask any relation between surface brightness and optical depth that has been found in nearby galaxies. Hence, we conclude that the SDSS spectral catalog is an excellent way to find occulting pairs and construct a uniform local sample. However, higher resolution than the SDSS images is needed to disentangle the effects of spiral arms and Hubble type from evolution since z = 0.2. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0708/0708.1119v1.pdf"}
{"id": "0708.1492", "abstract": "  The nature of dark matter is one of the outstanding questions of astrophysics. The internal motions of member stars reveal that the lowest luminosity galaxies in the Local Group are the most dark-matter dominated. New large datasets allow one to go further, and determine systematic properties of their dark matter haloes. We summarise recent results, emphasising the critical role of the dwarf spheroidal galaxies in understanding both dark matter and baryonic processes that shape galaxy evolution. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0708/0708.1492v1.pdf"}
{"id": "0708.1746", "abstract": "  The diversity in wealth and social status is present not only among humans, but throughout the animal world. We account for this observation by generating random variables that determ ine the social diversity of players engaging in the prisoner's dilemma game. Here the term social diversity is used to address extrinsic factors that determine the mapping of game pay offs to individual fitness. These factors may increase or decrease the fitness of a player depending on its location on the spatial grid. We consider different distributions of extrin sic factors that determine the social diversity of players, and find that the power-law distribution enables the best promotion of cooperation. The facilitation of the cooperative str ategy relies mostly on the inhomogeneous social state of players, resulting in the formation of cooperative clusters which are ruled by socially high-ranking players that are able to prevail against the defectors even when there is a large temptation to defect. To confirm this, we also study the impact of spatially correlated social diversity and find that coopera tion deteriorates as the spatial correlation length increases. Our results suggest that the distribution of wealth and social status might have played a crucial role by the evolution of cooperation amongst egoistic individuals. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0708/0708.1746v2.pdf"}
{"id": "0708.2989", "abstract": "  We present a method for fast optimal estimation of the temperature angular power spectrum from observations of the cosmic microwave background. We employ a Hamiltonian Monte Carlo (HMC) sampler to obtain samples from the posterior probability distribution of all the power spectrum coefficients given a set of observations. We compare the properties of the HMC and the related Gibbs sampling approach on low-resolution simulations and find that the HMC method performs favourably even in the regime of relatively low signal-to-noise. We also demonstrate the method on high-resolution data by applying it to simulated WMAP data. Analysis of a WMAP-sized data set is possible in a around eighty hours on a high-end desktop computer. HMC imposes few conditions on the distribution to be sampled and provides us with an extremely flexible approach upon which to build. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0708/0708.2989v2.pdf"}
{"id": "0709.3001", "abstract": "  Superdeformed states in light N=Z nuclei are studied by means of the self-consistent cranking calculation (i.e., the P + QQ model based on the cranked Hartree-Fock-Bogoliubov method). Analyses are given for two typical cases of superdeformed bands in the A ≃ 40 mass region, that is, bands where backbending is absent (^40Ca) and present (^36Ar). Investigations are carried out, particularly for the following points: cross-shell excitations in the sd and pf shells; the role of the g_9/2 and d_5/2 orbitals; the effect of the nuclear pairing; and the interplay between triaxiality and band termination. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0709/0709.3001v1.pdf"}
{"id": "0711.0423", "abstract": "  Radiatively-driven transfer flow perpendicular to a luminous disk is examined in the relativistic regime of (v/c)^2, taking into account the gravity of the central object. The flow is assumed to be vertical, and the gas pressure as well as the magnetic field are ignored. Using a velocity-dependent variable Eddington factor, we can solve the rigorous equations of the relativistic radiative flow accelerated up to the relativistic speed. For sufficiently luminous cases, the flow resembles the case without gravity. For less-luminous or small initial radius cases, however, the flow velocity decreases due to gravity. Application to a supercritical accretion disk with mass loss is briefly discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.0423v1.pdf"}
{"id": "0711.1639", "abstract": "  We study the dynamics of the \"Kolkata Paise Restaurant problem\". The problem is the following: In each period, N agents have to choose between N restaurants. Agents have a common ranking of the restaurants. Restaurants can only serve one customer. When more than one customer arrives at the same restaurant, one customer is chosen at random and is served; the others do not get the service. We first introduce the one-shot versions of the Kolkata Paise Restaurant problem which we call one-shot KPR games. We then study the dynamics of the Kolkata Paise Restaurant problem (which is a repeated game version of any given one shot KPR game) for large N. For statistical analysis, we explore the long time steady state behavior. In many such models with myopic agents we get under-utilization of resources, that is, we get a lower aggregate payoff compared to the social optimum. We study a number of myopic strategies, focusing on the average occupation fraction of restaurants. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.1639v3.pdf"}
{"id": "0711.1781", "abstract": "  On Earth, the Dry Valleys of Antarctica provide the closest martian-like environment for the study of extremophiles. Colonies of bacteries are protected from the freezing temperatures, the drought and UV light. They represent almost half of the biomass of those regions. Due to there resilience, endolithes are one possible model of martian biota. We propose to use infrared spectroscopy to remotely detect those colonies even if there is no obvious sign of their presence. This remote sensing approach reduces the risk of contamination or damage to the samples. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.1781v1.pdf"}
{"id": "0711.4358", "abstract": "  The transfer of turbulent energy through an inertial range from the driving scale to dissipative scales in a kinetic plasma followed by the conversion of this energy into heat is a fundamental plasma physics process. A theoretical foundation for the study of this process is constructed, but the details of the kinetic cascade are not well understood. Several important properties are identified: (a) the conservation of a generalized energy by the cascade; (b) the need for collisions to increase entropy and realize irreversible plasma heating; and (c) the key role played by the entropy cascade–a dual cascade of energy to small scales in both physical and velocity space–to convert ultimately the turbulent energy into heat. A strategy for nonlinear numerical simulations of kinetic turbulence is outlined. Initial numerical results are consistent with the operation of the entropy cascade. Inertial range turbulence arises in a broad range of space and astrophysical plasmas and may play an important role in the thermalization of fusion energy in burning plasmas. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.4358v1.pdf"}
{"id": "0711.4907", "abstract": "  The atmospheric structure of chemically peculiar stars deviates from that of normal stars with similar fundamental parameters due to unusual chemistry, abundance inhomogeneities and the presence of strong magnetic field. These effects are not considered in the standard model atmospheres, possibly leading to large errors in the stellar parameter determination and abundance analysis. To tackle this problem we used the state-of-the-art opacity sampling model atmosphere code LLmodels to calculate comprehensive grid of new generation model atmospheres for magnetic CP stars. This grid covers the whole parameter space occupied by SrCrEu and Si-peculiar stars, taking into account characteristic temperature dependence of the chemical abundances. Here we present the first results of our model atmosphere calculations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.4907v1.pdf"}
{"id": "0712.1723", "abstract": "  We introduce a new class of deterministic networks by associating networks with Diophantine equations, thus relating network topology to algebraic properties. The network is formed by representing integers as vertices and by drawing cliques between M vertices every time that M distinct integers satisfy the equation. We analyse the network generated by the Pythagorean equation x^2+y^2= z^2 showing that its degree distribution is well approximated by a power law with exponential cut-off. We also show that the properties of this network differ considerably from the features of scale-free networks generated through preferential attachment. Remarkably we also recover a power law for the clustering coefficient. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0712/0712.1723v1.pdf"}
{"id": "0712.2846", "abstract": "  We consider fermion-dimer scattering in the presence of a large positive scattering length in the frame of functional renormalization group equations. A flow equation for the momentum dependent fermion-dimer scattering amplitude is derived from first principles in a systematic vertex expansion of the exact flow equation for the effective action. The resummation obtained from the nonperturbative flow is shown to be equivalent to the one performed by the integral equation by Skorniakov and Ter-Martirosian (STM). The flow equation approach allows to integrate out fermions and bosons simultaneously, in line with the fact that the bosons are not fundamental but build up gradually as fluctuation induced bound states of fermions. In particular, the STM result for atom-dimer scattering is obtained by choosing the relative cutoff scales of fermions and bosons such that the fermion fluctuations are integrated out already at the initial stage of the RG evolution. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0712/0712.2846v2.pdf"}
{"id": "0712.4083", "abstract": "  The work considers the damped Pinney equation, defined as the model arising when a linear in velocity damping term is included in the Pinney equation. In the general case the resulting equation does not admit Lie point symmetries or is reducible to a simpler form by any obvious coordinate transformation. In this context the method of Kuzmak-Luke is applied to derive a perturbation solution, for weak damping and slow time-dependence of the frequency function. The perturbative and numerical solutions are shown to be in good agreement. The results are applied to examine the time-evolution of Gaussian shaped wave-functions in the Kostin formulation of dissipative quantum mechanics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0712/0712.4083v3.pdf"}
{"id": "0801.2812", "abstract": "  We construct full strong exceptional collections of line bundles on smooth toric Fano Deligne-Mumford stacks of Picard number at most two and of any Picard number in dimension two. It is hoped that the approach of this paper will eventually lead to the proof of the existence of such collections on all smooth toric nef-Fano Deligne-Mumford stacks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.2812v4.pdf"}
{"id": "0801.2860", "abstract": "  Topological quantum computation with Fibonacci anyons relies on the possibility of efficiently generating unitary transformations upon pseudoparticles braiding. The crucial fact that such set of braids has a dense image in the unitary operations space is well known; in addition, the Solovay-Kitaev algorithm allows to approach a given unitary operation to any desired accuracy. In this paper, the latter task is fulfilled with an alternative method, in the SU(2) case, based on a generalization of the geodesic dome construction to higher dimension. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.2860v1.pdf"}
{"id": "0801.3291", "abstract": "  Classification of complex wave functions of infinite variables is an important problem since it is related to the classification of possible quantum states of matter. In this paper, we propose a way to classify symmetric polynomials of infinite variables using the pattern of zeros of the polynomials. Such a classification leads to a construction of a class of simple non-Abelian quantum Hall states which are closely related to parafermion conformal field theories. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.3291v2.pdf"}
{"id": "0801.3454", "abstract": "  We present, as a very general method, an effective field theory to analyze models defined over small-world networks. Even if the exactness of the method is limited to the paramagnetic regions and to some special limits, it gives the exact critical behavior and the exact critical surfaces and percolation thresholds, and provide a clear and immediate (also in terms of calculation) insight of the physics. The underlying structure of the non random part of the model, i.e., the set of spins staying in a given lattice L_0 of dimension d_0 and interacting through a fixed coupling J_0, is exactly taken into account. When J_0≥0, the small-world effect gives rise to the known fact that a second order phase transition takes place, independently of the dimension d_0 and of the added random connectivity c. However, when J_0<0, a completely different scenario emerges where, besides a spin glass transition, multiple first- and second-order phase transitions may take place. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.3454v4.pdf"}
{"id": "0802.0161", "abstract": "  We present an introductory discussion of deep-inelastic lepton-proton scattering as a means to probe the substructure of the proton. A resume of QCD is given, emphasizing the running of the coupling constant and the DGLAP evolution equations for the parton densities. The determination of parton distributions is discussed and their importance for predictions of processes at the LHC is emphasized. Going beyond the pure DGLAP regime, we briefly discuss the behaviour of parton densities at low x, and the evidence for non-linear absorptive contributions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.0161v1.pdf"}
{"id": "0802.0207", "abstract": "  The formation of the first generations of stars at redshifts z > 15-20 signaled the transition from the simple initial state of the universe to one of increasing complexity. We here review recent progress in understanding the assembly process of the first galaxies, starting with cosmological initial conditions and modelling the detailed physics of star formation. In particular, we study the role of HD cooling in ionized primordial gas, the impact of UV radiation produced by the first stars, and the propagation of the supernova blast waves triggered at the end of their brief lives. We conclude by discussing how the chemical abundance patterns observed in extremely low-metallicity stars allow us to probe the properties of the first stars. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.0207v1.pdf"}
{"id": "0802.0798", "abstract": "  The best level of ordering and straightening of carbon nanotube arrays is often achieved when they are grown in a dielectric matrix, so such structures present the most suitable candidates for future channeling experiments with carbon nanotubes. Consequently, we investigate here how the dynamic polarization of carbon valence electrons in the presence of various surrounding dielectric media affects the angular distributions of protons channeled through (11, 9) single-wall carbon nanotubes. Proton speeds between 3 and 10 a.u., corresponding to energies of 0.223 and 2.49 MeV, are chosen with the nanotube's length varied between 0.1 and 1 μm. We describe the repulsive interaction between a proton and the nanotube's atoms in a continuum-potential approximation based on the Doyle-Turner potential, whereas the attractive image force on a proton is calculated using a two-dimensional hydrodynamic model for the dynamic response of the nanotube valence electrons, while assigning to the surrounding medium an appropriate (frequency dependent) dielectric function. The angular distributions of channeled protons are generated using a computer simulation method which solves the proton equations of motion in the transverse plane numerically. Our analysis shows that the presence of a dielectric medium can strongly affect both the appearance and positions of maxima in the angular distributions of channeled protons. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.0798v1.pdf"}
{"id": "0802.2518", "abstract": "  We illustrate an iterative method for retrieving the internuclear separations of N_2, O_2 and CO_2 molecules using the high-order harmonics generated from these molecules by intense infrared laser pulses. We show that accurate results can be retrieved with a small set of harmonics and with one or few alignment angles of the molecules. For linear molecules the internuclear separations can also be retrieved from harmonics generated using isotropically distributed molecules. By extracting the transition dipole moment from the high-order harmonic spectra, we further demonstrated that it is preferable to retrieve the interatomic separation iteratively by fitting the extracted dipole moment. Our results show that time-resolved chemical imaging of molecules using infrared laser pulses with femtosecond temporal resolutions is possible. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.2518v1.pdf"}
{"id": "0803.0672", "abstract": "  Within the minimal supersymmetric extension of the Standard Model, the mass of the light CP-even Higgs boson is computed to three-loop accuracy, taking into account the next-to-next-to-leading order effects from supersymmetric Quantum Chromodynamics. We consider two different scenarios for the mass hierarchies of the supersymmetric spectrum. Our numerical results amount to corrections of about 500 MeV which is of the same order as the experimental accuracy expected at the CERN Large Hadron Collider (LHC). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0803/0803.0672v2.pdf"}
{"id": "0803.1814", "abstract": "  This paper offers a new point of view on component separation, based on a model of additive components which enjoys a much greater flexibility than more traditional linear component models. This flexibility is needed to process the complex full-sky observations of the CMB expected from the Planck space mission, for which it was developed, but it may also be useful in any context where accurate component separation is needed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0803/0803.1814v1.pdf"}
{"id": "0803.2344", "abstract": "  This document introduces basics in data preparation, feature selection and learning basics for high energy physics tasks. The emphasis is on feature selection by principal component analysis, information gain and significance measures for features. As examples for basic statistical learning algorithms, the maximum a posteriori and maximum likelihood classifiers are shown. Furthermore, a simple rule based classification as a means for automated cut finding is introduced. Finally two toolboxes for the application of statistical learning techniques are introduced. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0803/0803.2344v1.pdf"}
{"id": "0803.4240", "abstract": "  We study in detail the fitness landscape of a difficult cellular automata computational task: the majority problem. Our results show why this problem landscape is so hard to search, and we quantify the large degree of neutrality found in various ways. We show that a particular subspace of the solution space, called the \"Olympus\", is where good solutions concentrate, and give measures to quantitatively characterize this subspace. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0803/0803.4240v1.pdf"}
{"id": "0803.4314", "abstract": "  We discuss the limit of small width for the Laplacian defined on a waveguide with Robin boundary conditions. Under suitable hypothesis on the scaling of the curvature, we prove the convergence of the Robin Laplacian to the Laplacian on the corresponding graph. We show that the projections on each transverse mode generically give rise to decoupling conditions between the edges of the graph while exceptionally a coupling can occur. The non decoupling conditions are related to the existence of resonances at the thresholds of the continuum spectrum. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0803/0803.4314v2.pdf"}
{"id": "0804.3574", "abstract": "  We report on the optical identification of the companion to the eclipsing millisecond pulsar PSR J1701-3006B in the globular cluster NGC 6266. A relatively bright star with an anomalous red colour and an optical variability (∼ 0.2 mag) that nicely correlates with the orbital period of the pulsar (∼ 0.144 days) has been found nearly coincident with the pulsar nominal position. This star is also found to lie within the error box position of an X-ray source detected by Chandra observations, thus supporting the hypothesis that some interaction is occurring between the pulsar wind and the gas streaming off the companion. Although the shape of the optical light curve is suggestive of a tidally deformed star which has nearly completely filled its Roche lobe, the luminosity (∼ 1.9 L_⊙) and the surface temperature (∼ 6000 K) of the star, deduced from the observed magnitude and colours, would imply a stellar radius significantly larger than the Roche lobe radius. Possible explanations for this apparent inconsistency are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0804/0804.3574v1.pdf"}
{"id": "0805.0975", "abstract": "  We analyzed the ^93Nb on ^natMg reaction at 30 MeV/nucleon in the aim of disentangling binary sequential decay and multifragmentation decay close to the energy threshold, i.e. ≃ 3 MeV/nucleon. Using the backtracing technique applied to the statistical models GEMINI and SMM we reconstruct simulated charge, mass and excitation energy distributions and compare them to the experimental ones. We show that data are better described by SMM than by GEMINI in agreement with the fact that multifragmentation is responsible for fragment production at excitation energies around 3 MeV/nucleon. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.0975v1.pdf"}
{"id": "0805.4306", "abstract": "  In this paper we consider the possible existence of unstable axisymmetric modes in Kerr space times, resulting from exponentially growing solutions of the Teukolsky equation. We describe a transformation that casts the radial equation that results upon separation of variables in the Teukolsky equation, in the form of a Schrödinger equation, and combine the properties of the solutions of this equations with some recent results on the asymptotic behaviour of spin weighted spheroidal harmonics to prove the existence of an infinite family of unstable modes. Thus we prove that the stationary region beyond a Kerr black hole inner horizon is unstable under gravitational linear perturbations. We also prove that Kerr space-time with angular momentum larger than its square mass, which has a naked singularity, is unstable. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.4306v3.pdf"}
{"id": "0805.4831", "abstract": "  Using recent advances in auxiliary-field quantum Monte Carlo techniques and the phaseless approximation to control the sign/phase problem, we determine the equation of state in the ground state of the two-dimensional repulsive single-band Hubbard model at intermediate interactions. Shell effects are eliminated and finite-size effects are greatly reduced by boundary condition integration. Spin-spin correlation functions and structure factors are also calculated. In lattice sizes up to 16× 16, the results show signal for phase-separation. Upon doping, the system separates into one phase of density n=1 (hole-free) and the other at density n_c (∼ 0.9). The long-range antiferromagnetic order is coupled to this process, and is lost below n_c. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.4831v2.pdf"}
{"id": "0806.2188", "abstract": "  Inspired by Knill's scheme for message passing error detection, here we develop a scheme for message passing error correction for the nine-qubit Bacon-Shor code. We show that for two levels of concatenated error correction, where classical information obtained at the first level is used to help interpret the syndrome at the second level, our scheme will correct all cases with four physical errors. This results in a reduction of the logical failure rate relative to conventional error correction by a factor proportional to the reciprocal of the physical error rate. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0806/0806.2188v1.pdf"}
{"id": "0807.0055", "abstract": "  A monolithic pixel sensor in deep-submicron Silicon-On-Insulator (SOI) CMOS technology has been designed, manufactured and characterised. This technology is of significant interest for applications in particle tracking and imaging. The prototype chip features pixels of 10 micron pitch arrayed in two analog sections and one digital section with a comparator and a latch integrated in each pixel. The prototype response has been tested with infrared lasers and with the 1.35 GeV electron beam extracted from the injection booster at the LBNL Advanced Light Source. Results from irradiation tests with low energy protons and neutrons performed at the LBNL 88-inch Cyclotron are also presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.0055v1.pdf"}
{"id": "0807.0194", "abstract": "  The tunnel current of a Luttinger liquid with a finite density of strong impurities is calculated using an instanton approach. For very low temperatures T or electric fields E the (nonlinear) conductivity is of variable range hopping (VRH) type as for weak pinning. For higher temperatures or fields the conductivity shows power law behavior corresponding to a crossover from multi- to single-impurity tunneling. For even higher T and not too strong pinning there is a second crossover to weak pinning. The determination of the position of the various crossover lines both for strong and weak pinning allows the construction of the global regime diagram. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.0194v1.pdf"}
{"id": "0807.0894", "abstract": "  We further investigate, in the planar limit of N=4 supersymmetric Yang Mills theories,the high energy Regge behavior of six-point MHV scattering amplitudes. In particular, for the new Regge cut contribution found in our previous paper, we compute in the leading logarithmic approximation (LLA) the energy spectrum of the BFKL equation in the color octet channel, and we calculate explicitly the two loop corrections to the discontinuities of the amplitudes for the transitions 2 to 4 and 3 to 3. We find an explicit solution of the BFKL equation for the octet channel for arbitrary momentum transfers and investigate the intercepts of the Regge singularities in this channel. As an important result we find that the universal collinear and infrared singularities of the BDS formula are not affected by this Regge-cut contribution. Any improvement of the BDS formula should reproduce this cut to all orders in the coupling. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.0894v2.pdf"}
{"id": "0807.2434", "abstract": "  We present limits on transit timing variations and secondary eclipse depth variations at 8 microns with the Spitzer Space Telescope IRAC camera. Due to the weak limb darkening in the infrared and uninterrupted observing, Spitzer provides the highest accuracy transit times for this bright system, in principle providing sensitivity to secondary planets of Mars mass in resonant orbits. Finally, the transit data provides tighter constraints on the wavelength- dependent atmospheric absorption by the planet. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.2434v1.pdf"}
{"id": "0807.3457", "abstract": "  We use time-evolutions of the linear perturbation equations to study the oscillations of rapidly rotating neutrons stars. Our models account for the buoyancy due to composition gradients and we study, for the first time, the nature of the resultant g-modes in a fast spinning star. We provide detailed comparisons of non-stratified and stratified models. This leads to an improved understanding of the relationship between the inertial modes of a non-stratified star and the g-modes of a stratified system. In particular, we demonstrate that each g-mode becomes rotation-dominated, i.e. approaches a particular inertial mode, as the rotation rate of the star is increased. We also discuss issues relating to the gravitational-wave driven instability of the various classes of oscillation modes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.3457v3.pdf"}
{"id": "0807.3775", "abstract": "  In this talk, I discuss how we may approach physics at the seesaw- and GUT-scales using data from the TeV scale. Even though we cannot hope to directly reach these energy scales using particle accelerators, we may get convinced of grand unification and seesaw mechanism based on experimental data if Nature is kind to us. In addition, we may find compelling reason to believe in leptogenesis based on experimental data. This cannot be achieved by a single experiment, but rather a collection of them, based on LHC, ILC, neutrino oscillation, neutrinoless double beta decay, direct dark matter detection, CMB power spectrum and its tensor mode. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.3775v1.pdf"}
{"id": "0808.0083", "abstract": "  Quantal effects on growth of spinodal instabilities in charge asymmetric nuclear matter are investigated in the framework of a stochastic mean field approach. Due to quantal effects, in both symmetric and asymmetric matter, dominant unstable modes shift towards longer wavelengths and modes with wave numbers larger than the Fermi momentum are strongly suppressed. As a result of quantum statistical effects, in particular at lower temperatures, magnitude of density fluctuations grows larger than those calculated in semi-classical approximation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.0083v1.pdf"}
{"id": "0808.0100", "abstract": "  We propose a systematic method to extract conformal loop models for rational conformal field theories (CFT). Method is based on defining an ADE model for boundary primary operators by using the fusion matrices of these operators as adjacency matrices. These loop models respect the conformal boundary conditions. We discuss the loop models that can be extracted by this method for minimal CFTs and then we will give dilute O(n) loop models on the square lattice as examples for these loop models. We give also some proposals for WZW SU(2) models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.0100v2.pdf"}
{"id": "0808.1817", "abstract": "  We use reduced fidelity approach to characterize quantum phase transitions in the one-dimensional spin-1/2 dimerized Heisenberg chain in the antiferromagnetic case. The reduced fidelity susceptibilities between two nearest-neighboring spin pairs are considered. We find that they are directly related to the square of the second derivative of the ground-state energy. This enables us to conclude that the former might be a more effective indicator of the second-order quantum phase transitions than the latter. Two further exemplifications are given to confirm the conclusion is available for a broad class of systems with SU(2) and translation symmetries. Moreover, a general connection between reduced fidelity susceptibility and quantum phase transitions is illustrated. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.1817v3.pdf"}
{"id": "0808.3507", "abstract": "  We study pairing vibrations in ^18,20,22O and ^42,44,46Ca nuclei solving the time-dependent Hartree-Fock-Bogoliubov equation in coordinate space with spherical symmetry. We use the SLy4 Skyrme functional in the normal part of the energy density functional and a local density dependent functional in its pairing part. Pairing vibrations are excited by two-neutron transfer operators. Strength distributions are obtained using the Fourier transform of the time-dependent response of two-neutron pair-transfer observables in the linear regime. Results are in overall agreement with quasiparticle random phase approximation calculations for Oxygen isotopes, though differences appear when increasing the neutron number. Both low lying pairing modes and giant pairing vibrations (GPV) are discussed. The GPV is observed in the Oxygen but not in the Calcium isotopes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.3507v2.pdf"}
{"id": "0808.4141", "abstract": "  We study the stability of standing shock waves in advection-dominated accretion flows into a Schwarzschild black hole by 2D general relativistic hydrodynamic simulations as well as linear analysis in the equatorial plane. We demonstrate that the accretion shock is stable against axisymmetric perturbations but becomes unstable to non-axisymmetric perturbations. The results of dynamical simulations show good agreement with linear analysis on the stability, oscillation and growing time scales. The comparison of different wave-travel times with the growth time scales of the instability suggests that the instability is likely to be of the Papaloizou-Pringle type, induced by the repeated propagations of acoustic waves. However, the wavelengths of perturbations are too long to clearly define the reflection point. By analyzing the non-linear phase in the dynamical simulations, it is shown that quadratic mode couplings precede the non-linear saturation. It is also found that not only short-term random fluctuations by turbulent motions but also quasi periodic oscillations take place on longer time scales in the non-linear phase. We give some possible implications of the instability for quasi periodic oscillations (QPOs) and the central engine for gamma ray bursts (GRBs). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.4141v1.pdf"}
{"id": "0809.5195", "abstract": "  High auditory sensitivity, sharp frequency selectivity, and otoacoustic emissions are signatures of active amplification of the cochlea. The human ear can also detect very large amplitude sound without being damaged as long as the exposed time is not too long. The outer hair cells are believed as the best candidate for the active force generator of the mammalian cochlea. In this paper, we propose a new model for the basilar membrane oscillation which successfully describes both the active and the protective mechanisms by employing an energy depot concept and a critical velocity of the basilar membrane. One of the main results is that thermal noise in the absence of external stimulation can be amplified leading to the spontaneous basilar membrane oscillation. The compressive response of the basilar membrane at the characteristic frequency and the dynamic response to the stimulation are consistent with the experimental results as expected. Our model also shows the nonlinear distortion of the response of the basilar membrane. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.5195v1.pdf"}
{"id": "0810.1187", "abstract": "  This paper studies the frequency/time selective K-user Gaussian interference channel with secrecy constraints. Two distinct models, namely the interference channel with confidential messages and the one with an external eavesdropper, are analyzed. The key difference between the two models is the lack of channel state information (CSI) about the external eavesdropper. Using interference alignment along with secrecy pre-coding, it is shown that each user can achieve non-zero secure Degrees of Freedom (DoF) for both cases. More precisely, the proposed coding scheme achieves K-2/2K-2 secure DoF with probability one per user in the confidential messages model. For the external eavesdropper scenario, on the other hand, it is shown that each user can achieve K-2/2K secure DoF in the ergodic setting. Remarkably, these results establish the positive impact of interference on the secrecy capacity region of wireless networks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.1187v1.pdf"}
{"id": "0810.4097", "abstract": "  Nonthermal X-rays and very high-energy (VHE) γ-rays have been detected from the supernova remnant (SNR) RX J1713.7-3946, and especially the recent observations with the Suzaku satellite clearly reveal a spectral cutoff in the X-ray spectrum, which directly relates to the cutoff of the energy spectrum of the parent electrons. However, whether the origin of the VHE γ-rays from the SNR is hadronic or leptonic is still in debate. We studied the multi-band nonthermal emission from RX J1713.7-3946 based on a semi-analytical approach to the nonlinear shock acceleration process by including the contribution of the accelerated electrons to the nonthermal radiation. The results show that the multi-band observations on RX J1713.7-3946 can be well explained in the model with appropriate parameters and the TeV γ-rays have hadronic origin, i.e., they are produced via proton-proton (p-p) interactions as the relativistic protons accelerated at the shock collide with the ambient matter. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.4097v2.pdf"}
{"id": "0811.1527", "abstract": "  Using numerical modeling we study emergence of structure and structure-related nonlinear conduction properties in the self-assembled nanoparticle films. Particularly, we show how different nanoparticle networks emerge within assembly processes with molecular bio-recognition binding. We then simulate the charge transport under voltage bias via single-electron tunnelings through the junctions between nanoparticles on such type of networks. We show how the regular nanoparticle array and topologically inhomogeneous nanonetworks affect the charge transport. We find long-range correlations in the time series of charge fluctuation at individual nanoparticles and of flow along the junctions within the network. These correlations explain the occurrence of a large nonlinearity in the simulated and experimentally measured current-voltage characteristics and non-Gaussian fluctuations of the current at the electrode. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.1527v1.pdf"}
{"id": "0811.4563", "abstract": "  Finding the causes for the nonstatistical vibrational energy relaxation in the planar carbonyl sulfide (OCS) molecule is a longstanding problem in chemical physics: Not only is the relaxation incomplete long past the predicted statistical relaxation time, but it also consists of a sequence of abrupt transitions between long-lived regions of localized energy modes. We report on the phase space bottlenecks responsible for this slow and uneven vibrational energy flow in this Hamiltonian system with three degrees of freedom. They belong to a particular class of two-dimensional invariant tori which are organized around elliptic periodic orbits. We relate the trapping and transition mechanisms with the linear stability of these structures. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.4563v1.pdf"}
{"id": "0812.1610", "abstract": "  The Color Glass Condensate picture of the nuclear wave function at small-x successfully predicted the suppressed production of high-pT particles at forward rapidities in deuteron-gold collisions at RHIC. This triggered more efforts which resulted in theoretical improvements and predictions for different observables which will provide further phenomenological tests. I review recent theoretical developments and discuss the resulting predictions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.1610v1.pdf"}
{"id": "0812.3017", "abstract": "  In the framework of the braneworld models, rotating black holes can be described by the Kerr metric with a tidal charge representing the influence of the non-local gravitational (tidal) effects of the bulk space Weyl tensor onto the black hole spacetime. We study the influence of the tidal charge onto profiled spectral lines generated by radiating tori orbiting in vicinity of a rotating black hole. We show that with lowering the negative tidal charge of the black hole, the profiled line becomes to be flatter and wider keeping their standard character with flux stronger at the blue edge of the profiled line. The extension of the line grows with radius falling and inclination angle growing. With growing inclination angle a small hump appears in the profiled lines due to the strong lensing effect of photons coming from regions behind the black hole. For positive tidal charge (b>0) and high inclination angles two small humps appear in the profiled lines close to the red and blue edge of the lines due to the strong lensing effect. We can conclude that for all values of b, the strongest effect on the profiled lines shape (extension) is caused by the changes of the inclination angle. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.3017v1.pdf"}
{"id": "0812.4065", "abstract": "  Three-body correlations for the ground-state decay of the lightest two-proton emitter ^6Be are studied both theoretically and experimentally. Theoretical studies are performed in a three-body hyperspherical-harmonics cluster model. In the experimental studies, the ground state of ^6Be was formed following the α decay of a ^10C beam inelastically excited through interactions with Be and C targets. Excellent agreement between theory and experiment is obtained demonstrating the existence of complicated correlation patterns which can elucidate the structure of ^6Be and, possibly, of the A=6 isobar. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.4065v1.pdf"}
{"id": "0901.0497", "abstract": "  We show that an explicit counting of Gribov copies can shed light on the infrared behavior of non-abelian gauge theories. A power-law growth of the number of copies suppresses gluon propagation while the distribution of copies along a gauge orbit implies an enhanced density of small eigenvalues of the Fadeev-Popov operator. Both of these phenomena are related to confinement. The discreteness in the number of copies and the associated nonlocality also has implications for vacuum energy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.0497v1.pdf"}
{"id": "0901.2585", "abstract": "  We address phase-shift estimation by means of squeezed vacuum probe and homodyne detection. We analyze Bayesian estimator, which is known to asymptotically saturate the classical Cramer-Rao bound to the variance, and discuss convergence looking at the a posteriori distribution as the number of measurements increases. We also suggest two feasible adaptive methods, acting on the squeezing parameter and/or the homodyne local oscillator phase, which allow to optimize homodyne detection and approach the ultimate bound to precision imposed by the quantum Cramer-Rao theorem. The performances of our two-step methods are investigated by means of Monte Carlo simulated experiments with a small number of homodyne data, thus giving a quantitative meaning to the notion of asymptotic optimality. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.2585v2.pdf"}
{"id": "0901.2651", "abstract": "  Magnetic tunnel junctions (MTJ) with AlOx barrier were fabricated by a deposition tool called Biased Target Ion Beam Deposition (BTIBD) using low energy ion source (0-50 eV) and voltage biased targets. The BTIBD system applies bias voltage directly and only on the desired targets, providing enough sputtering energy and avoiding \"overspill\" contamination during film deposition. The successful deposition of AlOx-MTJs demonstrated the capability of BTIBD to make multilayer structures with good film quality. MTJ thin film surface roughness and intermixing between layers are among the key problems leading to low TMR performance. Here by studying the bias voltage effect on MTJ properties via the measurement of Neel coupling field and TMR, we suggest that the lower bias voltage reduces the intermixing that occurs when top CoFe free layer is deposited on AlOx barrier, but produces relatively high surface roughness. On the other hand, higher energy deposition enhances both interlayer mixing and surface flattening. Such understanding of bias voltage effects on film properties could be used to optimize the MTJ performances. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.2651v1.pdf"}
{"id": "0902.2303", "abstract": "  We consider topological solitons in the CP^n sigma models in two space dimensions. In particular, we study \"kinks\", which are independent of one coordinate up to a rotation of the target space, and \"chains\", which are periodic in one coordinate up to a rotation of the target space. Kinks and chains both exhibit constituents, similar to monopoles and calorons in SU(n) Yang-Mills-Higgs and Yang-Mills theories. We examine the constituent structure using Lie algebras. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.2303v2.pdf"}
{"id": "0903.0523", "abstract": "  In this paper we review some properties of fuzzy observables, mainly as realized by commutative positive operator valued measures. In this context we discuss two representation theorems for commutative positive operator valued measures in terms of projection valued measures and describe, in some detail, the general notion of fuzzification. We also make some related observations on joint measurements. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.0523v1.pdf"}
{"id": "0903.1512", "abstract": "  We study the phenomenology of supersymmetric models that explain neutrino masses through the spontaneous breaking of R-parity, finding strong correlations between the decays of the lightest neutralino and the neutrino mixing angles. In addition, the existence of a Goldstone boson, usually called Majoron (J), completely modifies the phenomenology with respect to the standard picture, inducing large invisible branching ratios and charged lepton decays, like μ→ e J, interesting signals that can be used to constrain the model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.1512v1.pdf"}
{"id": "0903.1809", "abstract": "  We study the dynamics of dissipative spins for general spin-spin coupling. We investigate the population dynamics and relaxation of the purity in the white noise regime, in which exact results are available. Inter alia, we find distinct reduction of decoherence and slowdown of purity decay around degeneracy points. We also determine in analytic form the one-phonon exchange contribution to decoherence and relaxation in the ohmic quantum noise regime valid down to zero temperature. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.1809v1.pdf"}
{"id": "0903.1883", "abstract": "  We investigate the damping of the baryon acoustic oscillations in the matter power spectrum due to the quasinonlinear clustering and redshift-space distortions by confronting the models with the observations of the Sloan Digital Sky Survey luminous red galaxy sample. The chi-squared test suggests that the observed power spectrum is better matched by models with the damping of the baryon acoustic oscillations rather than the ones without the damping. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.1883v1.pdf"}
{"id": "0903.1909", "abstract": "  Several networks occurring in real life have modular structures that are arranged in an hierarchical fashion. In this paper, we have proposed a model for such networks, using a stochastic generation method. Using this model we show that, the scaling relation between the clustering and degree of the nodes is not a necessary property of hierarchical modular networks, as had previously been suggested on the basis of a deterministically constructed model. We also look at dynamics on such networks, in particular, the stability of equilibria of network dynamics and of synchronized activity in the network. For both of these, we find that, increasing modularity or the number of hierarchical levels tends to increase the probability of instability. As both hierarchy and modularity are seen in natural systems, which necessarily have to be robust against environmental fluctuations, we conclude that additional constraints are necessary for the emergence of hierarchical structure, similar to the occurrence of modularity through multi-constraint optimization as shown by us previously. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.1909v1.pdf"}
{"id": "0904.4556", "abstract": "  The possible role of decoherence due to space-time foam is discussed within the context of two models, one based on string/brane theory. and the other based on properties of black hole horizons in general relativity. It is argued that the density matrix satisfies a dissipative master equation, primarily from the study of renormalization group flows in non-critical string theory.This interpretation of the zero mode of the Liouville field as time leads necessarily to the CPT operator being ill defined. One striking consequence is that the quantum mechanical correlations of pair states of neutral mesons produced in meson factories are changed from the usual EPR state. The magnitude of this departure from EPR correlations is characterised by a parameter ω. The predicted value of ω is very small or zero. However it is shown explicitly that the the non-vanishing of ω is only a feature of the model based on string/brane theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0904/0904.4556v1.pdf"}
{"id": "0905.0336", "abstract": "  We study the performance of a multidimensional matched filter as a follow-up module of the coherent method recently developed by two of us for the detection of gravitational wave bursts by spherical resonant detectors. We have tested this strategy on the same set of injections used for the coherent method and found that the matched filter sensibly improves the determination of relevant parameters as the arrival time, amplitude, central frequency and arrival direction of the signal. The matched filter also improves the false alarm rate, reducing it roughly by a factor of 3. The hierarchical structure of the whole analysis pipeline allows to obtain these results without a significant increase of the computation time. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.0336v2.pdf"}
{"id": "0905.1119", "abstract": "  Everything in the Universe is assumed to be compromised of pure reversible quantum Toffoli gates, including empty space itself. Empty space can be configured into photon or matter gates simply by swapping logic input information with these entities through the phenomenon of quantum mechanical entanglement between photons and empty space Toffoli gates. The essential difference between empty space, photons and matter gates are the logic input values of their respective Toffoli gates. Empty space is characterized by an inability for the logic inputs to influence the internal logic state of its Toffoli gates since the control lines are set to logic 0. Photons and matter are characterized by Toffoli gates where the control lines are set to logic 1 enabling their logic inputs to control their internal logic states allowing for their interaction according to the laws of physics associated with reality. Photons swapping logic input information with empty space results in the propagation of light. Photons facilitating the swapping of information between matter and empty space gates leads to the laws of motion including relativity. This model enables the derivation of many physical laws from purely quantum mechanical considerations including the Heisenberg Uncertainty Principle, the Lorentz transformations of special relativity, and the relationship between relativistic energy and mass. The model provides a possible explanation for many physical phenomena including dark matter, anti-matter, and an inflationary Universe. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.1119v2.pdf"}
{"id": "0905.3257", "abstract": "  We present a method for constructing parent Hamiltonians for the chiral spin liquid. We find two distinct Hamiltonians for which the chiral spin liquid on a square lattice is an exact zero-energy ground state. We diagonalize both Hamiltonians numerically for 16-site lattices, and find that the chiral spin liquid, modulo its two-fold topological degeneracy, is indeed the unique ground state for one Hamiltonian, while it is not unique for the other. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.3257v3.pdf"}
{"id": "0906.0567", "abstract": "  We present new precision radial velocities and a three-planet Keplerian orbit fit for the V = 8.5, G5 V star HIP 14810. We began observing this star at Keck Observatory as part of the N2K Planet Search Project. Wright et al. (2007) announced the inner two planets to this system, and subsequent observations have revealed the outer planet planet and the proper orbital solution for the middle planet. The planets have minimum masses of 3.9, 1.3, and 0.6 M_Jup and orbital periods of 6.67, 147.7, and 952 d, respectively. We have numerically integrated the family of orbital solutions consistent with the data and find that they are stable for at least 10^6 yr. Our photometric search shows that the inner planet does not transit. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.0567v1.pdf"}
{"id": "0907.2144", "abstract": "  Infrared (IR) light is considered important for short-range wireless communication, thermal sensing, spectroscopy, material processing, medical surgery, astronomy etc. However, IR light is in general much harder to transport than optical light or microwave radiation. Existing hollow-core IR waveguides usually use a layer of metallic coating on the inner wall of the waveguide. Such a metallic layer, though reflective, still absorbs guided light significantly due to its finite Ohmic loss, especially for transverse-magnetic (TM) light. In this paper, we show that metal-wire based metamaterials may serve as an efficient TM reflector, reducing propagation loss of the TM mode by two orders of magnitude. By further imposing a conventional metal cladding layer, which reflects specifically transverse-electric (TE) light, we can potentially obtain a low-loss hollow-core fiber. Simulations confirm that loss values for several low-order modes are comparable to the best results reported so far. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.2144v1.pdf"}
{"id": "0907.2285", "abstract": "  We present the result of our extensive intranight optical monitoring of the well known low-energy peaked BL Lac (LBL) object PKS 0735+178. This long-term follow-up consists of R-band monitoring for a minimum duration of ∼ 4 hours, on 17 nights spanning 11 years (1998-2008). Using the CCD as an N-star photometer, a detection limit of around 1", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.2285v1.pdf"}
{"id": "0907.4779", "abstract": "  We study the matter-wave bistability in coupled atom-molecule quantum gases, in which heteronuclear molecules are created via an interspecies Feshbach resonance involving either two-species Bose or two-species Fermi atoms at zero temperature. We show that the resonant two-channel Bose model is equivalent to the nondegenerate parametric down-conversion in quantum optics, while the corresponding Fermi model can be mapped to a quantum optics model that describes a single-mode laser field interacting with an ensemble of inhomogeneously broadened two-level atoms. Using these analogy and the fact that both models are subject to the Kerr nonlinearity due to the two-body s-wave collisions, we show that under proper conditions, the population in the molecular state in both models can be made to change with the Feshbach detuning in a bistable fashion. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.4779v1.pdf"}
{"id": "0908.0251", "abstract": "  We propose a simple method for incorporating correlations into the impact parameter space description of multiple (semi-)hard partonic collisions in high energy hadron-hadron scattering. The perturbative QCD input is the standard factorization theorem for inclusive dijet production with a lower cutoff on transverse momentum. The width of the transverse distribution of hard partons is fixed by parameterizations of the two-gluon form factor. We then reconstruct the hard contribution to the total inelastic profile function and obtain corrections due to correlations to the more commonly used eikonal description. Estimates of the size of double correlation corrections are based on the rate of double collisions measured at the Tevatron. We find that, if typical values for the lower transverse momentum cutoff are used in the calculation of the inclusive hard dijet cross section, then the correlation corrections are necessary for maintaining consistency with expectations for the total inelastic proton-proton cross section at LHC energies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0908/0908.0251v2.pdf"}
{"id": "0908.1521", "abstract": "  We assume that, in equilibrium, nuclear matter at reduced density and moderate finite temperature, breaks up into many fragments. A strong support to this assumption is provided by date accumulated from intermediate energy heavy ion collisions. The break-up of hot and expanded nuclear matter according to rules of equilibrium statistical mechanics is the multifragmentation model. The model gives a first order phase transition. This is studied in detail here. Phase-equilibrium lines for different degrees of asymmetry are computed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0908/0908.1521v1.pdf"}
{"id": "0908.2830", "abstract": "  Gamma rays from extragalactic sources are attenuated by pair-production interactions with diffuse photons of the extragalactic background light (EBL). Gamma-ray bursts (GRBs) are a source of high-redshift photons above 10 GeV, and could be therefore useful as a probe of the evolving UV background radiation. In this paper, we develop a simple phenomenological model for the number and redshift distribution of gamma-ray bursts that can be seen at GeV energies with the Fermi satellite and MAGIC atmospheric Cherenkov telescope. We estimate the observed number of gamma rays per year, and show how this result is modified by considering interactions with different realizations of the evolving EBL. We also discuss the bright Fermi GRB 080916C in the context of this model. We find that the LAT on Fermi can be expected to see a small number of photons above 10 GeV each year from distant GRBs. Annual results for ground-based instruments like MAGIC are highly variable due to the low duty cycle and sky coverage of the telescope. However, successfully viewing a bright or intermediate GRB from the ground could provide hundreds of photons from high redshift, which would almost certainly be extremely useful in constraining both GRB physics and the high-redshift EBL. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0908/0908.2830v1.pdf"}
{"id": "0908.3242", "abstract": "  By using the density functional theory method, we systematically study the influences of the doping of an Al atom on the electronic structures of the Mg(0001) surface and dissociation behaviors of H2 molecules. We find that for the Al-doped surfaces, the surface relaxation around the doping layer changes from expansion of a clean Mg(0001) surface to contraction, due to the redistribution of electrons. After doping, the work function is enlarged, and the electronic states around the Fermi energy have a major distribution around the doping layer. For the dissociation of H2 molecules, we find that the energy barrier is enlarged for the doped surfaces. Especially, when the Al atom is doped at the first layer, the energy barrier is enlarged by 0.30 eV. For different doping lengths, however, the dissociation energy barrier decreases slowly to the value on a clean Mg(0001) surface when the doping layer is far away from the top surface. Our results well describe the electronic changes after Al-doping for the Mg(0001) surface, and reveal some possible mechanisms for improving the resistance to corrosion of the Mg(0001) surface by doping of Al atoms. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0908/0908.3242v2.pdf"}
{"id": "0909.0775", "abstract": "  A theoretical description for the radial density profile of a finite number of identical charged particles confined in a harmonic trap is developed for application over a wide range of Coulomb coupling (or, equivalently, temperatures) and particle numbers. A simple mean field approximation neglecting correlations yields a density profile which is monotonically decreasing with radius for all temperatures, in contrast to molecular dynamics simulations and experiments showing shell structure at lower temperatures. A more complete theoretical description including charge correlations is developed here by an extension of the hypernetted chain approximation, developed for bulk fluids, to the confined charges. The results reproduce all of the qualitative features observed in molecular dynamics simulations and experiments. These predictions are then tested quantitatively by comparison with new benchmark Monte Carlo simulations. Quantitative accuracy of the theory is obtained for the selected conditions by correcting the hypernetted chain approximation with a representation for the associated bridge functions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.0775v1.pdf"}
{"id": "0909.0791", "abstract": "  Quantum-optical coherence tomography (Q-OCT) is an interferometric technique for axial imaging offering several advantages over conventional methods. Chirped-pulse interferometry (CPI) was recently demonstrated to exhibit all of the benefits of the quantum interferometer upon which Q-OCT is based. Here we use CPI to measure axial interferograms to profile a sample accruing the important benefits of Q-OCT, including automatic dispersion cancellation, but with 10 million times higher signal. Our technique solves the artifact problem in Q-OCT and highlights the power of classical correlation in optical imaging. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.0791v1.pdf"}
{"id": "0909.1149", "abstract": "  We provide a bound on the minimum error when discriminating among quantum states, using the no-signaling principle. The bound is general in that it depends on neither dimensions nor specific structures of given quantum states to be discriminated among. We show that the bound is tight for the minimum-error state discrimination between symmetric (both pure and mixed) qubit states. Moreover, the bound can be applied to a set of quantum states for which the minimum-error state discrimination is not known yet. Finally, our results strengthen the quantitative connection between two no-go theorems, the no-signaling principle and the no perfect state estimation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.1149v2.pdf"}
{"id": "0909.2627", "abstract": "  We study pulse propagation in one-dimensional chains of spherical granules decorated with small grains placed between large granules. The effect of the small granules can be captured by replacing the decorated chains by undecorated chains of large granules of appropriately renormalized mass and effective interaction between the large granules. This allows us to obtain simple analytic expressions for the pulse propagation properties using a generalization of the binary collision approximation introduced in our earlier work [Phys. Rev. E in print (2009); Phys. Rev. E 69, 037601 (2004)] ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.2627v1.pdf"}
{"id": "0909.2844", "abstract": "  We investigate mode coupling in a two dimensional compressible disc with radial stratification and differential rotation. We employ the global radial scaling of linear perturbations and study the linear modes in the local shearing sheet approximation. We employ a three-mode formalism and study the vorticity (W), entropy (S) and compressional (P) modes and their coupling properties. The system exhibits asymmetric three-mode coupling: these include mutual coupling of S and P-modes, S and W-modes, and asymmetric coupling between the W and P-modes. P-mode perturbations are able to generate potential vorticity through indirect three-mode coupling. This process indicates that compressional perturbations can lead to the development of vortical structures and influence the dynamics of radially stratified hydrodynamic accretion and protoplanetary discs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.2844v1.pdf"}
{"id": "0910.0611", "abstract": "  We study the phantom-like behavior of a DGP-inspired braneworld scenario where curvature correction on the brane is taken into account. We include a possible modification of the induced gravity on the brane by incorporating higher order curvature terms of Gauss-Bonnet type. We investigate the cosmological implications of the model and we show that the normal branch of the scenario self-accelerates in this modified scenario without introducing any dark energy component. Also, a phantom-like behavior can be realized in this model without introducing any phantom field that suffers from serious difficulties such as violation of the null energy condition. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.0611v2.pdf"}
{"id": "0910.0681", "abstract": "  Recently, it is observed [Md. Nurujjaman et al, Phy. Rev. E 80, 015201 (R) (2009)] that in an excitable system, one can maintain noise induced coherency in the coherence resonance by blocking the destructive effect of the noise on the system at higher noise level. This phenomenon of constant coherence resonance (CCR) cannot be explained by the existing way of simulation of the model equations of an excitable system with added noise. In this paper, we have proposed a general model which explains the noise induced resonance phenomenon CCR as well as coherence resonance (CR) and stochastic resonance (SR). The simulation has been carried out considering the basic mechanism of noise induced resonance phenomena: noise only perturbs the system control parameter to excite coherent oscillations, taking proper precautions so that the destructive effect of noise does not affect the system. In this approach, the CR has been obtained from the interference between the system output and noise, and the SR has been obtained by adding noise and a subthreshold signal. This also explains the observation of the frequency shift of coherent oscillations in the CCR with noise level. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.0681v2.pdf"}
{"id": "0910.0715", "abstract": "  We study observational implications of the stochastic gravitational wave background and a non-Gaussian feature of scalar perturbations on the curvaton mechanism of the generation of density/curvature fluctuations, and show that they can determine the properties of the curvaton in a complementary manner to each other. Therefore even if Planck could not detect any non-Gaussianity, future space-based laser interferometers such as DECIGO or BBO could practically exhaust its parameter space. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.0715v1.pdf"}
{"id": "0910.3957", "abstract": "  We present time-dependent density matrix renormalization group (DMRG) results for strongly interacting one dimensional fermionic systems at finite temperature. When interactions are strong the characteristic spin energy can be greatly suppressed relative to the characteristic charge energy, allowing for the possibility of spin-incoherent Luttinger liquid physics when the temperature is high compared to the spin energy, but small compared to the charge energy. Using DMRG we compute the spectral properties of the t-J model at arbitrary temperatures with respect to both spin and charge energies. We study the full crossover from the Luttinger liquid regime to the spin-incoherent regime,focusing on small J/t, where the signatures of spin-incoherent behavior are more manifest. Our method allows us to access the analytically intractable regime where temperature is of the order of the spin energy, T∼ J. Our results should be helpful in the interpretation of experiments that may be in the crossover regime, T∼ J, and apply to one-dimensional cold atomic gases where finite-temperature effects are appreciable. The technique may also be used to guide the development of analytical approximations for the crossover regime. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.3957v1.pdf"}
{"id": "0910.4688", "abstract": "  This work considers the problem of quickest detection of signals in a coupled system of N sensors, which receive continuous sequential observations from the environment. It is assumed that the signals, which are modeled a general Ito processes, are coupled across sensors, but that their onset times may differ from sensor to sensor. The objective is the optimal detection of the first time at which any sensor in the system receives a signal. The problem is formulated as a stochastic optimization problem in which an extended average Kullback- Leibler divergence criterion is used as a measure of detection delay, with a constraint on the mean time between false alarms. The case in which the sensors employ cumulative sum (CUSUM) strategies is considered, and it is proved that the minimum of N CUSUMs is asymptotically optimal as the mean time between false alarms increases without bound. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.4688v1.pdf"}
{"id": "0911.4305", "abstract": "  We have designed three ASICs for possible applications in the optical links of a new layer of pixel detector in the ATLAS experiment for the first phase of the LHC luminosity upgrade. The ASICs include a high-speed driver for the VCSEL, a receiver/decoder to decode the signal received at the PIN diode to extract the data and clock, and a clock multiplier to produce a higher frequency clock to serialize the data for transmission. These ASICs were designed using a 130 nm CMOS process to enhance the radiation-hardness. We have characterized the fabricated ASICs and the submission has been mostly successful. We irradiated the ASICs with 24 GeV/c protons at CERN to a dosage of 70 Mrad. We observed no significant degradation except the driver circuit in the VCSEL driver fabricated using the thick oxide process in order to provide sufficient voltage to drive a VCSEL. The degradation is due to a large threshold shifts in the PMOS transistors used. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0911/0911.4305v1.pdf"}
{"id": "0912.3589", "abstract": "  Finding the three-dimensional representation of all or a part of a scene from a single two dimensional image is a challenging task. In this paper we propose a method for identifying the pose and location of objects with circular protrusions in three dimensions from a single image and a 3d representation or model of the object of interest. To do this, we present a method for identifying ellipses and their properties quickly and reliably with a novel technique that exploits intensity differences between objects and a geometric technique for matching an ellipse in 2d to a circle in 3d.   We apply these techniques to the specific problem of determining the pose and location of vehicles, particularly cars, from a single image. We have achieved excellent pose recovery performance on artificially generated car images and show promising results on real vehicle images. We also make use of the ellipse detection method to identify car wheels from images, with a very high successful match rate. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0912/0912.3589v1.pdf"}
{"id": "0912.4111", "abstract": "  Transition radiation from relativistic electrons is investigated in an ultrasonic superlattice excited in a finite thickness plate. In the quasi-classical approximation formulae are derived for the vector potential of the electromagnetic field and for the spectral-angular distribution of the radiation intensity. The acoustic waves generate new resonance peaks in the spectral and angular distribution of the radiation intensity. The heights of the peaks can be tuned by choosing the parameters of the acoustic wave. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0912/0912.4111v2.pdf"}
{"id": "0912.4840", "abstract": "  We study theoretically electronic Mach-Zehnder interferometers built from integer quantum Hall edge states, showing that the results of recent experiments can be understood in terms of multiparticle interference effects. These experiments probe the visibility of Aharonov-Bohm (AB) oscillations in differential conductance as an interferometer is driven out of equilibrium by an applied bias, finding a lobe pattern in visibility as a function of voltage. We calculate the dependence on voltage of the visibility and the phase of AB oscillations at zero temperature, taking into account long range interactions between electrons in the same edge for interferometers operating at a filling fraction ν=1. We obtain an exact solution via bosonization for models in which electrons interact only when they are inside the interferometer. This solution is non-perturbative in the tunneling probabilities at quantum point contacts. The results match observations in considerable detail provided the transparency of the incoming contact is close to one-half: the variation in visibility with bias voltage consists of a series of lobes of decreasing amplitude, and the phase of the AB-fringes is practically constant inside the lobes but jumps by π at the minima of the visibility. We discuss in addition the consequences of approximations made in other recent treatments of this problem. We also formulate perturbation theory in the interaction strength and use this to study the importance of interactions that are not internal to the interferometer. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0912/0912.4840v2.pdf"}
{"id": "1001.0734", "abstract": "  With references to recent observational results on the nebula IC59, we applied our previously developed Smoothed Particle Hydrodynamics (SPH) code which is based on Radiative Driven Implosion (RDI) model, to investigate the possible formation mechanism for the observed morphological structures of differently shaped BRCs. The simulation results confirmed the existence of the 4th type morphology of BRCs – type M BRC. We are able to find the necessary condition for the appearance of the type M BRC based on the fact that the simulated physical properties of the cloud are consistent with observations on IC59. More importantly, the prospect of RDI triggered star formation by RDI model in all of the observed type M BRCs is ruthlessly eliminated. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1001/1001.0734v1.pdf"}
{"id": "1001.2884", "abstract": "  In this paper, we give a tropical method for computing Gromov-Witten type invariants of Fano manifolds of special type. This method applies to those Fano manifolds which admit toric degenerations to toric Fano varieties with singularities allowing small resolutions. Examples include (generalized) flag manifolds of type A, and some moduli space of rank two bundles on a genus two curve. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1001/1001.2884v1.pdf"}
{"id": "1001.3028", "abstract": "  Despite the nice features of the Dvali, Gabadadze and Porrati (DGP) model to explain the late-time acceleration of the universe, it suffers from some theoretical problems like the ghost issue. We present a way to self-accelerate the normal DGP branch, which is known to be free of the ghost problem, by means of an f(R) term on the brane action. We obtain the de Sitter self-accelerating solutions of the model and study their stability under homogeneous perturbations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1001/1001.3028v1.pdf"}
{"id": "1001.3854", "abstract": "  Equations of motion for free higher-spin gauge fields of any symmetry can be formulated in terms of linearised curvatures. On the other hand, gauge invariance alone does not fix the form of the corresponding actions which, in addition, either contain higher derivatives or involve inverse powers of the d'Alembertian operator, thus introducing possible subtleties in degrees of freedom count. We suggest a path to avoid ambiguities, starting from local, unconstrained Lagrangians previously proposed, and integrating out the auxiliary fields from the functional integral, thus generating a unique non-local theory expressed in terms of curvatures. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1001/1001.3854v1.pdf"}
{"id": "1002.0316", "abstract": "  We use numerical simulations to study the crystallization of monodisperse systems of hard aspherical particles. We find that particle shape and crystallizability can be easily related to each other when particles are characterized in terms of two simple and experimentally accessible order parameters: one based on the particle surface-to-volume ratio, and the other on the angular distribution of the perturbations away from the ideal spherical shape. We present a phase diagram obtained by exploring the crystallizability of 487 different particle shapes across the two-order-parameter spectrum. Finally, we consider the physical properties of the crystalline structures accessible to aspherical particles, and discuss limits and relevance of our results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.0316v2.pdf"}
{"id": "1002.2242", "abstract": "  We aim at characterizing viability, invariance and some reachability properties of controlled piecewise deterministic Markov processes (PDMPs). Using analytical methods from the theory of viscosity solutions, we establish criteria for viability and invariance in terms of the first order normal cone. We also investigate reachability of arbitrary open sets. The method is based on viscosity techniques and duality for some associated linearized problem. The theoretical results are applied to general On/Off systems, Cook's model for haploinssuficiency, and a stochastic model for bacteriophage lambda. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.2242v1.pdf"}
{"id": "1002.2885", "abstract": "  We summarize recent observations and modeling of the brightest Sgr A* flare to be observed simultaneously in (near)-infrared and X-rays to date. Trying to explain the spectral characteristics of this flare through inverse Compton mechanisms implies physical parameters that are unrealistic for Sgr A*. Instead, a \"cooling break\" synchrotron model provides a more feasible explanation for the X-ray emission. In a magnetic field of about 5-30 Gauss the X-ray emitting electrons cool very quickly on the typical dynamical timescale while the NIR-emitting electrons cool more slowly. This produces a spectral break in the model between NIR and X-ray wavelengths that can explain the differences in the observed spectral indices. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.2885v1.pdf"}
{"id": "1003.1125", "abstract": "  We give a general definition of self-similar Lie algebras, and show that important examples of Lie algebras fall into that class. We give sufficient conditions for a self-similar Lie algebra to be nil, and prove in this manner that the self-similar algebras associated with Grigorchuk's and Gupta-Sidki's torsion groups are nil as well as self-similar. We derive the same results for a class of examples constructed by Petrogradsky, Shestakov and Zelmanov. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.1125v1.pdf"}
{"id": "1003.2138", "abstract": "  In smart grid, a home appliance can adjust its power consumption level according to the realtime power price obtained from communication channels. Most studies on smart grid do not consider the cost of communications which cannot be ignored in many situations. Therefore, the total cost in smart grid should be jointly optimized with the communication cost. In this paper, a probabilistic mechanism of locational margin price (LMP) is applied and a model for the stochastic evolution of the underlying load which determines the power price is proposed. Based on this framework of power price, the problem of determining when to inquire the power price is formulated as a Markov decision process and the corresponding elements, namely the action space, system state and reward function, are defined. Dynamic programming is then applied to obtain the optimal strategy. A simpler myopic approach is proposed by comparing the cost of communications and the penalty incurred by using the old value of power price. Numerical results show the significant performance gain of the optimal strategy of price inquiry, as well as the near-optimality of the myopic approach. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.2138v1.pdf"}
{"id": "1003.2144", "abstract": "  The Horava - Lifshitz (HL) theory has recently attracted a lot of interest as a viable solution to some quantum gravity related problems and the presence of an effective cosmological constant able to drive the cosmic speed up. We show here that, in the weak field limit, the HL proposal leads to a modification of the gravitational potential because of two additive terms (scaling respectively as r^2 and r^-4) to the Newtonian 1/r potential. We then derive a general expression to compute the rotation curve of an extended system under the assumption that the mass density only depends on the cylindrical coordinates (R, z) showing that the HL modification induces a dependence of the circular velocity on the mass function which is a new feature of the theory. As a first exploratory analysis, we then try fitting the Milky Way rotation curve using its visible components only in order to see whether the HL modified potential can be an alternative to the dark matter framework. This turns out not to be the case so that we argue that dark matter is still needed, but the amount of dark matter and the dark halo density profile have to be revised according to the new HL potential. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.2144v1.pdf"}
{"id": "1004.0709", "abstract": "  We show that a Dynamical AdS/QCD model is able to reproduce the linear Regge trajectories for the light-flavor sector of mesons with high spin and also for the scalar and pseudoscalar ones. In addition the model has confinement by the Wilson loop criteria and a mass gap. We also calculate the decay amplitude of scalars into two pion in good agreement to the available experimental data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.0709v1.pdf"}
{"id": "1004.2180", "abstract": "  In order to assess the physical mechanisms at stake when giant gas bubbles burst at the top of a magma conduit, laboratory experiments have been performed. An overpressurized gas cavity is initially closed by a thin liquid film, which suddenly bursts. The acoustic signal produced by the bursting is investigated. The key result is that the amplitude and energy of the acoustic signal strongly depend on the film rupture time. As the rupture time is uncontrolled in the experiments and in the field, the measurement of the acoustic excess pressure in the atmosphere, alone, cannot provide any information on the overpressure inside the bubble before explosion. This could explain the low energy partitioning between infrasound, seismic and explosive dynamics often observed on volcanoes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.2180v1.pdf"}
{"id": "1005.2710", "abstract": "  In this paper, we characterize the capacity of a new class of single-source multicast discrete memoryless relay networks having a tree topology in which the root node is the source and each parent node in the graph has at most one noisy child node and any number of noiseless child nodes. This class of multicast tree networks includes the class of diamond networks studied by Kang and Ulukus as a special case, where they showed that the capacity can be strictly lower than the cut-set bound. For achievablity, a novel coding scheme is constructed where each noisy relay employs a combination of decode-and-forward (DF) and compress-and-forward (CF) and each noiseless relay performs a random binning such that codebook constructions and relay operations are independent for each node and do not depend on the network topology. For converse, a new technique of iteratively manipulating inequalities exploiting the tree topology is used. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1005/1005.2710v2.pdf"}
{"id": "1005.5014", "abstract": "  We follow the nonequilibrium Green's function formalism to study time-dependent thermal transport in a linear chain system consisting of two semi-infinite leads connected together by a coupling that is harmonically modulated in time. The modulation is driven by an external agent that can absorb and emit energy. We determine the energy current flowing out of the leads exactly by solving numerically the Dyson equation for the contour-ordered Green's function. The amplitude of the modulated coupling is of the same order as the interparticle coupling within each lead. When the leads have the same temperature, our numerical results show that modulating the coupling between the leads may direct energy to either flow into the leads simultaneously or flow out of the leads simultaneously, depending on the values of the driving frequency and temperature. A special combination of values of the driving frequency and temperature exists wherein no net energy flows into or out of the leads, even for long times. When one of the leads is warmer than the other, net energy flows out of the warmer lead. For the cooler lead, however, the direction of the energy current flow depends on the values of the driving frequency and temperature. In addition, we find transient effects to become more pronounced for higher values of the driving frequency. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1005/1005.5014v2.pdf"}
{"id": "1005.5398", "abstract": "  Cygnus X-1 was the first X-ray source widely accepted to be a black hole candidate and remains among the most studied astronomical objects in its class. The detection of non-thermal radio, hard X-rays and gamma rays reveals the fact that this kind of objects are capable of accelerating particles up to very high energies.   In order to explain the electromagnetic emission from Cygnus X-1 in the low-hard state we present a model of a black hole corona with both relativistic lepton and hadron content. We characterize the corona as a two-temperature hot plasma plus a mixed non-thermal population in which energetic particles interact with magnetic, photon and matter fields. Our calculations include the radiation emitted by secondary particles (pions, muons and electron/positron pairs). Finally, we take into account the effects of photon absorption. We compare the results obtained from our model with data of Cygnus X-1 obtained by the COMPTEL instrument. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1005/1005.5398v1.pdf"}
{"id": "1006.2964", "abstract": "  Two-dimensional vortex dynamics in a ratchet washboard planar pinning potential (PPP) in the presence of thermal fluctuations is considered on the basis of a Fokker-Planck equation. Explicit expressions for two new nonlinear anisotropic voltages (longitudinal and transverse with respect to the current direction) are derived and analyzed. The physical origin of these odd (with respect to magnetic field or transport current direction reversal) voltages is caused by the interplay between the even effect of vortex guiding and the ratchet asymmetry. Both new voltages are going to zero in the linear regimes of the vortex motion (i.e. in the thermally activated flux flow (TAFF) and ohmic flux flow (FF) regimes) and have a bump-like current or temperature dependence in the vicinity of the highly nonlinear resistive transition from the TAFF to the FF. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1006/1006.2964v1.pdf"}
{"id": "1006.4441", "abstract": "  Molecular dynamics (MD) simulation with modified Brenner's reactive empirical bond order (REBO) potential is a powerful tool to investigate plasma wall interaction on divertor plates in a nuclear fusion device. However, MD simulation box's size is less than several nm for the performance of a computer. To extend the size of the MD simulation, we develop a hybrid simulation code between MD code using REBO potential and binary collision approximation (BCA) code. Using the BCA code instead of computing all particles with a high kinetic energy for every step in the MD simulation, considerable computation time is saved. By demonstrating a hydrogen atom injection on a graphite by the hybrid simulation code, it is found that the hybrid simulation code works efficiently in a large simulation box. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1006/1006.4441v2.pdf"}
{"id": "1007.1345", "abstract": "  In this paper we propose an improved approximation scheme for the Vector Bin Packing problem (VBP), based on the combination of (near-)optimal solution of the Linear Programming (LP) relaxation and a greedy (modified first-fit) heuristic. The Vector Bin Packing problem of higher dimension (d ≥2) is not known to have asymptotic polynomial-time approximation schemes (unless P = NP).   Our algorithm improves over the previously-known guarantee of (ln d + 1 + epsilon) by Bansal et al. [1] for higher dimensions (d > 2). We provide a θ(1) approximation scheme for certain set of inputs for any dimension d. More precisely, we provide a 2-OPT algorithm, a result which is irrespective of the number of dimensions d. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1007/1007.1345v1.pdf"}
{"id": "1007.1565", "abstract": "  We derive a Hamiltonian control theory which can be applied to a 4D symplectic map that models a ring particle accelerator composed of elements with sextupole nonlinearity. The controlled system is designed to exhibit a more regular orbital behavior than the uncontrolled one. Using the Smaller Alignement Index (SALI) chaos indicator, we are able to show that the controlled system has a dynamical aperture up to 1.7 times larger than the original mode ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1007/1007.1565v3.pdf"}
{"id": "1007.3008", "abstract": "  This proceeding reports a study of the impacts of the SB2009 beam parameters on the Higgs recoil mass and Higgs-Strahlung cross-section measurements based on a dedicated fast simulation algorithm of the ILD detector. The study shows worse results from SB2009 beam parameters than the previous RDR beam parameters, because of the smaller luminosity. However, Travel Focus (TF) technology can recover the degradation to certain level. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1007/1007.3008v1.pdf"}
{"id": "1007.4442", "abstract": "  In this paper we attempt a non-perturbative study of the five dimensional, anisotropic SU(2) gauge theory on the lattice using Monte-Carlo techniques. Our goal is the exploration of the phase diagram, define the various phases and the critical boundary lines. Three phases appear, two of them are continuations of the Strong and the Weak coupling phases of pure 4d SU(2) to non-zero coupling β^' in the fifth transverse direction and they are separated by a crossover transition, while the third phase is a 5D Coulombic phase. We provide evidence that the phase transition between the 5D Coulomb phase and the Weak coupling phase is a second order phase transition. Assuming that this result is not altered when increasing the lattice volume we give a first estimate of the associated critical exponents. This opens the possibility for a continuum effective five dimensional field theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1007/1007.4442v2.pdf"}
{"id": "1008.5309", "abstract": "  Systems of self-propelled particles are known for their tendency to aggregate and to display swarm behavior. We investigate two model systems, self-propelled rods interacting via volume exclusion, and sinusoidally-beating flagella embedded in a fluid with hydrodynamic interactions. In the flagella system, beating frequencies are Gaussian distributed with a non-zero average. These systems are studied by Brownian-dynamics simulations and by mesoscale hydrodynamics simulations, respectively. The clustering behavior is analyzed as the particle density and the environmental or internal noise are varied. By distinguishing three types of cluster-size probability density functions, we obtain a phase diagram of different swarm behaviors. The properties of clusters, such as their configuration, lifetime and average size are analyzed. We find that the swarm behavior of the two systems, characterized by several effective power laws, is very similar. However, a more careful analysis reveals several differences. Clusters of self-propelled rods form due to partially blocked forward motion, and are therefore typically wedge-shaped. At higher rod density and low noise, a giant mobile cluster appears, in which most rods are mostly oriented towards the center. In contrast, flagella become hydrodynamically synchronized and attract each other; their clusters are therefore more elongated. Furthermore, the lifetime of flagella clusters decays more quickly with cluster size than of rod clusters. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1008/1008.5309v1.pdf"}
{"id": "1009.2234", "abstract": "  The transport of angular momentum in the outward direction is the fundamental requirement for accretion to proceed in an accretion disc. This objective can be achieved if the accretion flow is turbulent. Instabilities are one of the sources for the turbulence. We study a differentially rotating compressive flow in the presence of non vanishing radial and azimuthal magnetic field and demonstrate the occurrence of a high growth rate instability. This instability operates in a region where magnetic energy density exceeds the rotational energy density. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.2234v1.pdf"}
{"id": "1009.2955", "abstract": "  In this paper, wireless systems operating under queueing constraints in the form of limitations on the buffer violation probabilities are considered. The throughput under such constraints is captured by the effective capacity formulation. It is assumed that finite blocklength codes are employed for transmission. Under this assumption, a recent result on the channel coding rate in the finite blocklength regime is incorporated into the analysis and the throughput achieved with such codes in the presence of queueing constraints and decoding errors is identified. Performance of different transmission strategies (e.g., variable-rate, variable-power, and fixed-rate transmissions) is studied. Interactions between the throughput, queueing constraints, coding blocklength, decoding error probabilities, and signal-to-noise ratio are investigated and several conclusions with important practical implications are drawn. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.2955v1.pdf"}
{"id": "1009.4428", "abstract": "  We study an improved AdS/QCD model at finite temperature and chemical potential. An Ansatz for the beta-function for the boundary theory allows for the derivation of a charged dilatonic black hole in bulk. The solution is asymptotically RN-AdS in the UV and AdS2 * R3 in the IR. We discuss the thermodynamical aspects of the solution. The fermionic susceptibilities are shown to deviate from the free fermionic limits at asymptotic temperatures despite the asymptotically free nature of the gauge coupling at the boundary. The Polyakov line, the temporal and spatial string tensions dependence on both temperature and chemical potential are also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.4428v2.pdf"}
{"id": "1009.4947", "abstract": "  The emission-line Be star HD 215227 lies within the positional error circle of the newly identified gamma-ray source AGL J2241+4454. We present new blue spectra of the star, and we point out the morphological and variability similarities to other Be binaries. An analysis of the available optical photometry indicates a variation with a period of 60.37 +/- 0.04 d, which may correspond to an orbital modulation of the flux from the disk surrounding the Be star. The distance to the star of 2.6 kpc and its relatively large Galactic latitude suggest that the binary was ejected from the plane by a supernova explosion that created the neutron star or black hole companion. The binary and runaway properties of HD 215227 make it an attractive candidate as the optical counterpart of AGL J2241+4454 and as a new member of the small class of gamma-ray emitting binaries. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.4947v1.pdf"}
{"id": "1009.5697", "abstract": "  The influence of the quadrupole shape fluctuations on the dipole vibrations in transitional nuclei is investigated in the framework of the Instantaneous Shape Sampling Model, which combines the Interacting Boson Model for the slow collective quadrupole motion with the Random Phase Approximation for the rapid dipole vibrations. Coupling to the complex background configurations is taken into account by folding the results with a Lorentzian with an energy dependent width. The low-energy energy portion of the γ- absorption cross section, which is important for photo-nuclear processes, is studied for the isotopic series of Kr, Xe, Ba, and Sm. The experimental cross sections are well reproduced. The low-energy cross section is determined by the Landau fragmentation of the dipole strength and its redistribution caused by the shape fluctuations. Collisional damping only wipes out fluctuations of the absorption cross section, generating the smooth energy dependence observed in experiment. In the case of semi-magic nuclei, shallow pygmy resonances are found in agreement with experiment. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.5697v1.pdf"}
{"id": "1010.0736", "abstract": "  We propose a method to reduce the relaxation time towards equilibrium in stochastic sampling of complex energy landscapes in statistical systems with discrete degrees of freedom by generalizing the platform previously developed for continuous systems. The method starts from a master equation, in contrast to the Fokker-Planck equation for the continuous case. The master equation is transformed into an imaginary-time Schrödinger equation. The Hamiltonian of the Schrödinger equation is modified by adding a projector to its known ground state. We show how this transformation decreases the relaxation time and propose a way to use it to accelerate simulated annealing for optimization problems. We implement our method in a simplified kinetic Monte Carlo scheme and show an acceleration by an order of magnitude in simulated annealing of the symmetric traveling salesman problem. Comparisons of simulated annealing are made with the exchange Monte Carlo algorithm for the three-dimensional Ising spin glass. Our implementation can be seen as a step toward accelerating the stochastic sampling of generic systems with complex landscapes and long equilibration times. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.0736v2.pdf"}
{"id": "1010.0799", "abstract": "  The seesaw mechanism is the most popular explanation for the smallness of neutrino masses. However, its high scale makes direct tests impossible and only indirect signals at low energies are reachable for collider experiments. One of these indirect links with the high scale is lepton flavor violation (LFV). We discuss LFV decays of sleptons in the context of a SUSY left-right symmetric model that naturally incorporates the seesaw mechanism. This non-minimal embedding of the seesaw leads to observable LFV effects in the right-handed sleptons sector, contrary to minimal models where these are found to be totally negligible. Therefore, LFV observables can be used as a powerful tool to study physics right below the GUT scale. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.0799v1.pdf"}
{"id": "1010.2878", "abstract": "  We consider joint measurement of two and three unsharp qubit observables through an Arthur-Kelly type joint measurement model for qubits. We investigate the effect of initial state of the detectors on the unsharpness of the measurement as well as the post-measurement state of the system. Particular emphasis is given on a physical understanding of the POVM to PVM transition in the model and entanglement between system and detectors.Two approaches for characterizing the unsharpness of the measurement and the resulting measurement uncertainty relations are considered.The corresponding measures of unsharpness are connected for the case where both the measurements are equally unsharp. The connection between the POVM elements and symmetries of the underlying Hamiltonian of the measurement interaction is made explicit and used to perform joint measurement in arbitrary directions. Finally in the case of three observables we derive a necessary condition for the approximate joint measurement and use it show the relative freedom available when the observables are non-orthogonal. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.2878v2.pdf"}
{"id": "1010.3323", "abstract": "  Multipoint or multichannel observations in plasmas can frequently be modelled as an instantaneous mixture of contributions (waves, emissions, ...) of different origins. Recovering the individual sources from their mixture then becomes one of the key objectives. However, unless the underlying mixing processes are well known, these situations lead to heavily underdetermined problems. Blind source separation aims at disentangling such mixtures with the least possible prior information on the sources and their mixing processes. Several powerful approaches have recently been developed, which can often provide new or deeper insight into the underlying physics. This tutorial paper briefly discusses some possible applications of blind source separation to the field of plasma physics, in which this concept is still barely known. Two examples are given. The first one shows how concurrent processes in the dynamical response of the electron temperature in a tokamak can be separated. The second example deals with solar spectral imaging in the Extreme UV and shows how empirical temperature maps can be built. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.3323v1.pdf"}
{"id": "1010.3444", "abstract": "  In recent years, ultracold atoms have emerged as an exceptionally controllable experimental system to investigate fundamental physics, ranging from quantum information science to simulations of condensed matter models. Here we go one step further and explore how cold atoms can be combined with other quantum systems to create new quantum hybrids with tailored properties. Coupling atomic quantum many-body states to an independently controllable single-particle gives access to a wealth of novel physics and to completely new detection and manipulation techniques. We report on recent experiments in which we have for the first time deterministically placed a single ion into an atomic Bose Einstein condensate. A trapped ion, which currently constitutes the most pristine single particle quantum system, can be observed and manipulated at the single particle level. In this single-particle/many-body composite quantum system we show sympathetic cooling of the ion and observe chemical reactions of single particles in situ. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.3444v1.pdf"}
{"id": "1010.3524", "abstract": "  DEPleted Field Effect Transistor (DEPFET) active pixel detectors combine a first amplification stage with a fully depleted sensor in one single device, resulting in a very good signal-to-noise ratio even for thin sensors. DEPFET pixels are produced in MOS technology with two metal and two poly-silicon layers and have been developed for the use in Xray imaging and tracking in particle physics experiments. The sensor concept will be presented and all aspects of operation will be detailed with the focus on its application at the upgraded detector Belle II under preparation for the high-luminosity upgrade of the e+e- KEKB collider in Japan. The stringent requirements on excellent spatial resolution can be met by cell sizes as small as 25x25 um2 and minimal material budget. The readout ASICs attached to the sensors will be described as well as the module design and the thinning technology employed to reduced the active sensor thickness to as little as 50 um. DEPFET prototype performance at lab and beam tests will be presented, as well as results of irradiations up to 8 MRad. Extensive simulation studies have been made to asses the vertexing and tracking performance of DEPFET-based vertex detector of Belle II. The main performance parameters will be shown, together with an overview of the project status ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.3524v1.pdf"}
{"id": "1010.3956", "abstract": "  Smart grid, equipped with modern communication infrastructures, is subject to possible cyber attacks. Particularly, false report attacks which replace the sensor reports with fraud ones may cause the instability of the whole power grid or even result in a large area blackout. In this paper, a trustiness system is introduced to the controller, who computes the trustiness of different sensors by comparing its prediction, obtained from Kalman filtering, on the system state with the reports from sensor. The trustiness mechanism is discussed and analyzed for the Linear Quadratic Regulation (LQR) controller. Numerical simulations show that the trustiness system can effectively combat the cyber attacks to smart grid. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.3956v1.pdf"}
{"id": "1010.4567", "abstract": "  We model the underdoped cuprates using fermions moving in a background with local antiferromagnetic order. The antiferromagnetic order fluctuates in orientation, but not in magnitude, so that there is no long-range antiferromagnetism, but a 'topological' order survives. The normal state is described as a fractionalized Fermi liquid (FL*), with electron-like quasiparticles coupled to the fractionalized excitations of the fluctuating antiferromagnet. The electronic quasiparticles reside near pocket Fermi surfaces enclosing total area x (the dopant density), centered away from the magnetic Brillouin zone boundary. The violation of the conventional Luttinger theorem is linked to a 'species doubling' of these quasiparticles. We describe phenomenological theories of the pairing of these quasiparticles, and show that a large class of mean-field theories generically displays a nodal-anti-nodal `dichotomy': the interplay of local antiferromagnetism and pairing leads to a small gap near the nodes of the d-wave pairing along the Brillouin zone diagonals, and a large gap in the anti-nodal region. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.4567v3.pdf"}
{"id": "1010.4836", "abstract": "  Combined recent data from cosmic-ray detectors and gamma-ray detectors have produced some surprising insights regarding the sources of ultrahigh-energy cosmic rays (UHECRs), magnetic fields inside and outside the Milky Way, and the universal photon backgrounds. The energy-dependent composition of UHECRs implies a non-negligible contribution of sources located in the Milky Way, such as past gamma-ray bursts that took place in our Galaxy. Extended halos of distant sources seen in the Fermi data imply that intergalactic magnetic fields have average strengths of the order of a femtogauss. Such relatively low magnetic fields imply that the protons from distant blazars generate a detectable flux of secondary gamma rays in their interactions with the photon background. A comparison with the data shows an excellent agreement of the secondary photons with the spectra of distant blazars observed by atmospheric Cherenkov telescopes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.4836v2.pdf"}
{"id": "1010.5224", "abstract": "  Recent measurements suggest that extensive air showers initiated by ultra-high energy cosmic rays (UHECR) emit signals in the microwave band of the electromagnetic spectrum caused by the collisions of the free-electrons with the atmospheric neutral molecules in the plasma produced by the passage of the shower. Such emission is isotropic and could allow the detection of air showers with 100", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.5224v2.pdf"}
{"id": "1010.5243", "abstract": "  Based on previous spectral and temporal optical studies, Q2122-444 has been classified as a naked AGN or true type 2 AGN, that is, an AGN that genuinely lacks a broad line region (BLR). Its optical spectrum seemed to possess only narrow forbidden emission lines that are typical of type 2 (obscured) AGNs, but the long-term optical light curve, obtained from a monitoring campaign over more than two decades, showed strong variability, apparently ruling out the presence of heavy obscuration. Here, we present the results from a  40 ks XMM-Newton observation of Q2122-444 carried out to shed light on the energetics of this enigmatic AGN. The X-ray analysis was complemented with ATCA radio data to assess the possible presence of a jet, and with new NTT/EFOSC2 optical spectroscopic data to verify the actual absence of a BLR. The higher-quality optical data revealed the presence of strong and broad Balmer lines that are at odds with the previous spectral classification of this AGN. The lack of detection of radio emission rules out the presence of a jet. The X-ray data combined with simultaneous UV observations carried out by the OM aboard XMM-Newton confirm that Q2122-444 is a typical type-1 AGN without any significant intrinsic absorption. New estimates of the black hole mass independently obtained from the broad Balmer lines and from a new scaling technique based on X-ray spectral data suggest that Q2122-444 is accreting at a relatively high rate in Eddington units. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.5243v1.pdf"}
{"id": "1011.3881", "abstract": "  We argue that both pocket-disappearing and neck-disrupting types of Lifshitz transitions can be realized in two-dimensional spin-density wave models for underdoped cuprates, and study both types of transitions with impurity scattering treated in the self-consistent Born approximation. We first solve for the electron self-energy from the self-consistent equation, and then study the low-temperature electrical conductivity and thermopower. Close to the Lifshitz transition, the thermopower is strongly enhanced. For the pocket-disappearing type, it has a sharp peak, while for the neck-disrupting type, it changes sign at the transition, with its absolute value peaked on both sides of the transition. We discuss possible applications to underdoped cuprates. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1011/1011.3881v1.pdf"}
{"id": "1011.4828", "abstract": "  We explore equilibrium solutions of non-topological solitons in a general class of scalar field theories which include global U(1) symmetry. We find new types of solutions, tube-shaped and crust-shaped objects, and investigate their stability. Like Q-balls, the new solitons can exist in supersymmetric extensions of the Standard Model, which may responsible for baryon asymmetry and dark matter. Therefore, observational signals of the new solitons would give us more informations on the early universe and supersymmetric theories. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1011/1011.4828v2.pdf"}
{"id": "1011.5821", "abstract": "  A broad program of measurements is planned for heavy ion collisions in ATLAS. With up to a factor of 30 increase in collision energy compared to existing data, significant new insights are anticipated to be obtained with the first data measured. Global features of the LHC collisions will be accessible with the early data and will set the stage for the precision measurements to follow. ATLAS is particularly well suited for exploration of \"jet quenching,\" the extinction of energetic jets in the hot dense medium. Observations of heavy quark jet suppression will be possible with unprecedented energy reach and statistical precision, potentially yielding new insights into the basic mechanisms involved. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1011/1011.5821v1.pdf"}
{"id": "1012.0780", "abstract": "  We show that, in a model of modified gravity based on the spectral action functional, there is a nontrivial coupling between cosmic topology and inflation, in the sense that the shape of the possible slow-roll inflation potentials obtained in the model from the nonperturbative form of the spectral action are sensitive not only to the geometry (flat or positively curved) of the universe, but also to the different possible non-simply connected topologies. We show this by explicitly computing the nonperturbative spectral action for some candidate flat cosmic topologies given by Bieberbach manifolds and showing that the resulting inflation potential differs from that of the flat torus by a multiplicative factor, similarly to what happens in the case of the spectral action of the spherical forms in relation to the case of the 3-sphere. We then show that, while the slow-roll parameters differ between the spherical and flat manifolds but do not distinguish different topologies within each class, the power spectra detect the different scalings of the slow-roll potential and therefore distinguish between the various topologies, both in the spherical and in the flat case. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.0780v1.pdf"}
{"id": "1012.0896", "abstract": "  The essential feature of weak measurements on quantum systems is the reduction of measurement back-action to negligible levels. To observe the non-classical features of weak measurements, it is therefore more important to avoid additional back-action errors than it is to avoid errors in the actual measurement outcome. In this paper, it is shown how an optical weak measurement of diagonal (PM) polarization can be realized by path interference between the horizontal (H) and vertical (V) polarization components of the input beam. The measurement strength can then be controlled by rotating the H and V polarizations towards each other. This well-controlled operation effectively generates the back-action without additional decoherence, while the visibility of the interference between the two beams only limits the measurement resolution. As the experimental results confirm, we can obtain extremely high weak values, even at rather low visibilities. Our method therefore provides a realization of weak measurements that is extremely robust against experimental imperfections. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.0896v2.pdf"}
{"id": "1012.2511", "abstract": "  In this paper we present the constraints on cold dark matter (CDM) isocurvature contributions to the cosmological perturbations. By employing Markov Chain Monte Carlo method (MCMC), we perform a global analysis for cosmological parameters using the latest astronomical data, such as 7-year Wilkinson Microwave Anisotropy Probe (WMAP7) observations, matter power spectrum from the Sloan Digital Sky Survey (SDSS) luminous red galaxies (LRG), and \"Union2\" type Ia Supernovae (SNIa) sample. We find that the correlated mixture of adiabatic and isocurvature modes are mildly better fitting to the current data than the pure adiabatic ones, with the minimal χ^2 given by the likelihood analysis being reduced by 3.5. We also obtain a tight limit on the fraction of the CDM isocurvature contributions, which should be less than 14.6", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.2511v2.pdf"}
{"id": "1012.3289", "abstract": "  We investigate the stability of growing vesicles using the formalism of nonequilibrium thermodynamics. The vesicles are growing due to the accretion of lipids to the bilayer which forms the vesicle membrane. The thermodynamic description is based on the hydrodynamics of a water/lipid mixture together with a model of the vesicle as a discontinuous system in the sense of linear nonequilibrium thermodynamics. This formulation allows the forces and fluxes relevant to the dynamic stability of the vesicle to be identified. The method is used to analyze the stability of a spherical vesicle against arbitrary axisymmetric perturbations. It is found that there are generically two critical radii at which changes of stability occur. In the case where the perturbation takes the form of a single zonal harmonic, only one of these radii is physical and is given by the ratio 2 L_p / L_γ, where L_p is the hydraulic conductivity and L_γ is the Onsager coefficient related to changes in membrane area due to lipid accretion. The stability of such perturbations is related to the value of l corresponding to the particular zonal harmonic: those with lower l are more unstable than those with higher l. Possible extensions of the current work and the need for experimental input are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.3289v2.pdf"}
{"id": "1012.3745", "abstract": "  We prove that each overtwisted contact structure has knot types that are represented by infinitely many distinct transverse knots all with the same self-linking number. In some cases, we can even classify all such knots. We also show similar results for Legendrian knots and prove a \"folk\" result concerning loose transverse and Legendrian knots (that is knots with overtwisted complements) which says that such knots are determined by their classical invariants (up to contactomorphism). Finally we discuss how these results partially fill in our understanding of the \"geography\" and \"botany\"' problems for Legendrian knots in overtwisted contact structures, as well as many open questions regarding these problems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.3745v2.pdf"}
{"id": "1012.4982", "abstract": "  A finite element approximation of the Stokes equations under a certain nonlinear boundary condition, namely, the slip or leak boundary condition of friction type, is considered. We propose an approximate problem formulated by a variational inequality, prove an existence and uniqueness result, present an error estimate, and discuss a numerical realization using an iterative Uzawa-type method. Several numerical examples are provided to support our theoretical results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.4982v1.pdf"}
{"id": "1101.0833", "abstract": "  We survey an area of recent development, relating dynamics to theoretical computer science. We discuss the theoretical limits of simulation and computation of interesting quantities in dynamical systems. We will focus on central objects of the theory of dynamics, as invariant measures and invariant sets, showing that even if they can be computed with arbitrary precision in many interesting cases, there exists some cases in which they can not. We also explain how it is possible to compute the speed of convergence of ergodic averages (when the system is known exactly) and how this entails the computation of arbitrarily good approximations of points of the space having typical statistical behaviour (a sort of constructive version of the pointwise ergodic theorem). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1101/1101.0833v2.pdf"}
{"id": "1101.6039", "abstract": "  Electromagnetically induced transparency (EIT) has mainly been modelled for three-level systems. In particular, a considerable interest has been dedicated to the Lambda-configuration, with two ground states and one excited state. However, in the alkali-metal atoms, which are commonly used, hyperfine interaction in the excited state introduces several levels which simultaneously participate in the scattering process. When the Doppler broadening is comparable with the hyperfine splitting in the upper state, the three-level Lambda model does not reproduce the experimental results. Here we theoretically investigate the EIT in a hot vapor of alkali-metal atoms and demonstrate that it can be strongly reduced due to the presence of multiple excited levels. Given this model, we also show that a well-designed optical pumping enables to significantly recover the transparency. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1101/1101.6039v4.pdf"}
{"id": "1102.0480", "abstract": "  In this paper, we design high order accurate and stable finite difference schemes for the initial-boundary value problem, associated with the magnetic induction equation with resistivity. We use Summation-By-Parts (SBP) finite difference operators to approximate spatial derivatives and a Simultaneous Approximation Term (SAT) technique for implementing boundary conditions. The resulting schemes are shown to be energy stable. Various numerical experiments demonstrating both the stability and the high order of accuracy of the schemes are presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.0480v1.pdf"}
{"id": "1102.0674", "abstract": "  Recommendation systems represent an important tool for news distribution on the Internet. In this work we modify a recently proposed social recommendation model in order to deal with no explicit ratings of users on news. The model consists of a network of users which continually adapts in order to achieve an efficient news traffic. To optimize network's topology we propose different stochastic algorithms that are scalable with respect to the network's size. Agent-based simulations reveal the features and the performance of these algorithms. To overcome the resultant drawbacks of each method we introduce two improved algorithms and show that they can optimize network's topology almost as fast and effectively as other not-scalable methods that make use of much more information. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.0674v1.pdf"}
{"id": "1102.1819", "abstract": "  We study the ground state phase diagram of the bilayer Heisenberg model on square lattice with a Bosonic RVB wave function. The wave function has the form of a Gutzwiller projected Schwinger Boson mean field ground state and involves two variational parameters. We find the wave function provides an accurate description of the system on both sides of the quantum phase transition. Especially, through the analysis of the spin structure factor, ground state fidelity susceptibility and the Binder moment ratio Q_2, a continuous transition from the antiferromagnetic ordered state to the quantum disordered state is found at the critical coupling of α_c=J_⊥/J_∥≈2.62, in good agreement with the result of quantum Monte Carlo simulation. The critical exponent estimated from the finite size scaling analysis(1/ν≈1.4) is consistent with that of the classical 3D Heisenberg universality class. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.1819v1.pdf"}
{"id": "1102.2832", "abstract": "  Standard order-disorder phase transition in the Ising model is described in terms of rates of processes of spin flips. This formulation allows to extend numerous results on phase transition for sciences other than physics of magnetism. We apply it to the problem of norm breaking. Two strategies: to cooperate or to defect, form an analogy to two spin orientations. An example is a crowd at an exit, where to defect means to push others, and to cooperate is to move slowly together. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.2832v3.pdf"}
{"id": "1103.0403", "abstract": "  An evacuation process is simulated within the Social Force Model. Thousand pedestrians are leaving a room by one exit. We investigate the stationarity of the distribution of time lags between instants when two successive pedestrians cross the exit. The exponential tail of the distribution is shown to gradually vanish. Taking fluctuations apart, the time lags decrease in time till there are only about 50 pedestrians in the room, then they start to increase. This suggests that at the last stage the flow is laminar. In the first stage, clogging events slow the evacuation down. As they are more likely for larger crowds, the flow is not stationary. The data are investigated with detrended fluctuation analysis. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.0403v1.pdf"}
{"id": "1103.2026", "abstract": "  The QED trace anomaly is calculated at one-loop level based on the loop regularization method which is realized in 4-dimensional spacetime and preserves gauge symmetry and Poincare symmetry in spite of the introduction of two mass scales, namely the ultraviolet (UV) cut-off M_c and infrared (IR) cut-off μ_s. It is shown that the dilation Ward identity which relates the three-point diagrams with the vacuum polarization diagrams gets the standard form of trace anomaly through quantum corrections in taking the consistent limit M_c→∞ and μ_s = 0 which recovers the original integrals. This explicitly demonstrates that the loop regularization method is indeed a self-consistent regularization scheme which is applicable to the calculations not only for the chiral anomaly but also for the trace anomaly, at least at one-loop level. It is also seen that the consistency conditions which relates the tensor-type and scalar-type irreducible loop integrals (ILIs) are crucial for obtaining a consistent result. As a comparison, we also present the one-loop calculations by using the usual Pauli-Villars regularization and the dimensional regularization. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.2026v2.pdf"}
{"id": "1103.4840", "abstract": "  Starting from first principles, we formulate a theory of wave packet propagation in a nonlinear, disordered medium of any dimension, through the derivation of a Fokker-Planck transport equation. Our theory is based on a diagrammatic expansion of the wave packet's density, and is supported by a heuristic picture that involves a Boltzmann equation with an effective, external potential. Our approach also confirms results obtained in previous work for two-dimensional, nonlinear disordered media. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.4840v2.pdf"}
{"id": "1103.6019", "abstract": "  We consider the extension of the last-in-first-out graph searching game of Giannopoulou and Thilikos to digraphs. We show that all common variations of the game require the same number of searchers, and the minimal number of searchers required is one more than the cycle-rank of the digraph. We also obtain a tight duality theorem, giving a precise min-max characterization of obstructions for cycle-rank. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.6019v2.pdf"}
{"id": "1105.2565", "abstract": "  We identify a diffeomorphism Lie algebra in the self-dual sector of Yang-Mills theory, and show that it determines the kinematic numerators of tree-level MHV amplitudes in the full theory. These amplitudes can be computed off-shell from Feynman diagrams with only cubic vertices, which are dressed with the structure constants of both the Yang-Mills colour algebra and the diffeomorphism algebra. Therefore, the latter algebra is the dual of the colour algebra, in the sense suggested by the work of Bern, Carrasco and Johansson. We further study perturbative gravity, both in the self-dual and in the MHV sectors, finding that the kinematic numerators of the theory are the BCJ squares of the Yang-Mills numerators. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.2565v2.pdf"}
{"id": "1105.3791", "abstract": "  The Muon Spectrometer (MS) of the ALICE experiment at LHC is equipped with a HLT (High Level Trigger), whose aim is to improve the accuracy of the trigger cuts delivered at the L0 stage. A computational challenge of real-time event reconstruction is satisfied to achieve this software trigger cut of the HLT. After the description of the online algorithms, the performance of the online tracker is compared with that of the offline tracker using the measured pp collisions at √(s)=7 TeV. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.3791v1.pdf"}
{"id": "1105.4249", "abstract": "  Strongly non-Newtonian fluids namely, aqueous gels of starch, are shown to exhibit visco-elastic behavior, when subjected to a load. We study arrowroot and potato starch gels. When a droplet of the fluid is sandwiched between two glass plates and compressed, the area of contact between the fluid and plates increases in an oscillatory manner. This is unlike Newtonian fluids, where the area increases monotonically in a similar situation. The periphery moreover, develops an instability, which looks similar to Saffman Taylor fingers. This is not normally seen under compression. The loading history is also found to affect the manner of spreading. We attempt to describe the non-Newtonian nature of the fluid through a visco-elastic model incorporating generalized calculus. This is shown to reproduce qualitatively the oscillatory variation in the surface strain. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.4249v1.pdf"}
{"id": "1105.5578", "abstract": "  Stability Selection was recently introduced by Meinshausen and Buhlmann (2010) as a very general technique designed to improve the performance of a variable selection algorithm. It is based on aggregating the results of applying a selection procedure to subsamples of the data. We introduce a variant, called Complementary Pairs Stability Selection (CPSS), and derive bounds both on the expected number of variables included by CPSS that have low selection probability under the original procedure, and on the expected number of high selection probability variables that are excluded. These results require no (e.g. exchangeability) assumptions on the underlying model or on the quality of the original selection procedure. Under reasonable shape restrictions, the bounds can be further tightened, yielding improved error control, and therefore increasing the applicability of the methodology. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.5578v2.pdf"}
{"id": "1105.5914", "abstract": "  A microscopic description of the zero energy two-body ground state and many-body static properties of anisotropic homogeneous gases of bosonic dipoles in two dimensions at low densities is presented and discussed. By changing the polarization angle with respect to the plane, we study the impact of the anisotropy, present in the dipole–dipole interaction, on the energy per particle, comparing the results with mean field predictions. We restrict the analysis to the regime where the interaction is always repulsive, although the strength of the repulsion depends on the orientation with respect to the polarization field. We present a series expansion of the solution of the zero energy two-body problem which allows us to find the scattering length of the interaction and to build a suitable Jastrow factor that we use as a trial wave function for both a variational and diffusion Monte Carlo simulation of the infinite system. We find that the anisotropy has an almost negligible impact on the ground state properties of the many-body system in the universal regime where the scattering length governs the physics of the system. We also show that scaling in the gas parameter persists in the dipolar case up to values where other isotropic interactions with the same scattering length yield different predictions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.5914v1.pdf"}
{"id": "1106.0383", "abstract": "  First-principles density-functional theory has been used to investigate equilibrium geometries, total energies, and diffusion barriers for H as an interstitial impurity absorbed in α-Fe. Internal strains/stresses upon hydrogen absorption are a crucial factor to understand preferred absorption sites and diffusion. For high concentrations, H absorbs near the octahedral site favoring a large tetragonal distortion of the BCC lattice. For low concentration, H absorbs near the tetrahedral site minimizing the elastic energy stored on nearby cells. Diffusion paths depend on the concentration regime too; hydrogen diffuses about ten times faster in the distorted BCT lattice. External stresses of several GPa modify barriers by ≈ 10", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.0383v1.pdf"}
{"id": "1106.1810", "abstract": "  We investigate escape of cosmic ray (CR) electrons from a supernova remnant (SNR) to interstellar space. We show that CR electrons escape in order from high energies to low energies like CR nuclei, while the escape starts later than the beginning of the Sedov phase at an SNR age of 10^3 - 7*10^3 yrs and the maximum energy of runaway CR electrons is below the knee about 0.3 - 50 TeV because unlike CR nuclei, CR electrons lose their energy due to synchrotron radiation. Highest energy CR electrons will be directly probed by AMS-02, CALET, CTA and LHAASO experiments, or have been already detected by H.E.S.S. and MAGIC as a cutoff in the CR electron spectrum. Furthermore, we also calculate the spatial distribution of runaway CR electrons and their radiation spectra around SNRs. Contrary to common belief, maximum-energy photons of synchrotron radiation around 1 keV are emitted by runaway CR electrons which have been caught up by the shock. Inverse Compton scattering by runaway CR electrons can dominate the gamma-ray emission from runaway CR nuclei via pion decay, and both are detectable by CTA and LHAASO as clues to the CR origin and the amplification of magnetic fluctuations around the SNR. We also discuss middle-aged and/or old SNRs as unidentified very-high-energy gamma-ray sources. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.1810v3.pdf"}
{"id": "1106.2567", "abstract": "  Local structure of NdFeAsO_1-xF_x (x=0.0, 0.05, 0.15 and 0.18) high temperature iron pnictide superconductor system is studied using arsenic K-edge extended x-ray absorption fine structure measurements as a function of temperature. Fe-As bondlength shows only a weak temperature and F-substitution dependence, consistent with the strong covalent nature of this bond. The temperature dependence of the mean-square relative-displacements of the Fe-As bondlength are well described by the correlated-Einstein model for all the samples, but with different Einstein-temperatures for the superconducting and non-superconducting samples. The results indicate distinct local Fe-As lattice dynamics in the superconducting and non-superconducting iron-pnictide systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.2567v1.pdf"}
{"id": "1107.1018", "abstract": "  A quantum mechanical explanation of the relaxation to equilibrium is shown for macroscopic systems for nonintegrable cases and numerically verified. The macroscopic system is initially in an equilibrium state, subsequently externally perturbed during a finite time, and then isolated for a sufficiently long time. We show a quantitative explanation that the initial microcanonical state typically reaches to a state whose expectation values are well-approximated by the average over another microcanonical ensemble. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.1018v1.pdf"}
{"id": "1107.3558", "abstract": "  To understand how systems of star clusters have reached their presently observed properties constitutes a powerful probe into the physics of cluster formation, without needing to resort to high spatial resolution observations of individual cluster-forming regions (CFRg) in distant galaxies. In this contribution I focus on the mass-radius relation of CFRgs, how it can be uncovered by studying the gas expulsion phase of forming star clusters, and what the implications are. I demonstrate that, through the tidal field impact upon exposed star clusters, the CFRg mass-radius relation rules cluster infant weight-loss in dependence of cluster mass. The observational constraint of a time-invariant slope for the power-law young cluster mass function is robustly satisfied by CFRgs with a constant mean volume density. In contrast, a constant mean surface density would be conducive to the preferential destruction of high-mass clusters. A purely dynamical line-of-reasoning leads therefore to a conclusion consistent with star formation a process driven by a volume density threshold. Developing this concept further, properties of molecular clumps and CFRgs naturally get dissociated. This allows to understand: (i) why the star cluster mass function is steeper than the molecular cloud (clump) mass function; (ii) the presence of a massive star formation limit in the mass-size space of molecular structures. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.3558v1.pdf"}
{"id": "1107.3895", "abstract": "  F00183-7111 is one of the most extreme Ultra-Luminous Infrared Galaxies known. Here we present a VLBI image which shows that F00183-7111 is powered by a combination of a radio-loud Active Galactic Nucleus surrounded by vigorous starburst activity. Although already radio-loud, the quasar jets are only 1.7 kpc long, boring through the dense gas and starburst activity that confine them. We appear to be witnessing this remarkable source in the brief transition period between merging starburst and radio-loud \"quasar-mode\" accretion. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.3895v1.pdf"}
{"id": "1107.5523", "abstract": "  In this paper we study spread codes: a family of constant-dimension codes for random linear network coding. In other words, the codewords are full-rank matrices of size (k x n) with entries in a finite field F_q. Spread codes are a family of optimal codes with maximal minimum distance. We give a minimum-distance decoding algorithm which requires O((n-k)k^3) operations over an extension field F_q^k. Our algorithm is more efficient than the previous ones in the literature, when the dimension k of the codewords is small with respect to n. The decoding algorithm takes advantage of the algebraic structure of the code, and it uses original results on minors of a matrix and on the factorization of polynomials over finite fields. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.5523v4.pdf"}
{"id": "1108.4800", "abstract": "  Microtubules have been in biophysical focus for several decades. Yet the confusing and mutually contradicting results regarding their elasticity and fluctuations have shed some doubts on their present understanding. In this paper we expose the empirical evidence for the existence of discrete GDP-tubulin fluctuations between a curved and a straight configuration at room temperature as well as for conformational tubulin cooperativity. Guided by a number of experimental findings, we build the case for a novel microtubule model, with the principal result that microtubules can spontaneously form micron size cooperative helical states with unique elastic and dynamic features. The polymorphic dynamics of the microtubule lattice resulting from the tubulin bistability quantitatively explains several experimental puzzles including anomalous scaling of dynamic fluctuations of grafted microtubules, their apparent length-stiffness relation and their remarkably curved-helical appearance in general. We point out that tubulin dimers's multistability and its cooperative switching could participate in important cellular processes, and could in particular lead to efficient mechanochemical signalling along single microtubules. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.4800v2.pdf"}
{"id": "1109.0497", "abstract": "  Additive symmetric Lévy noise can induce directed transport of overdamped particles in a static asymmetric potential. We study, numerically and analytically, the effect of an additional dichotomous random flashing in such Lévy ratchet system. For this purpose we analyze and solve the corresponding fractional Fokker-Planck equations and we check the results with Langevin simulations. We study the behavior of the current as function of the stability index of the Lévy noise, the noise intensity and the flashing parameters. We find that flashing allows both to enhance and diminish in a broad range the static Lévy ratchet current, depending on the frequencies and asymmetry of the multiplicative dichotomous noise, and on the additive Lévy noise parameters. Our results thus extend those for dichotomous flashing ratchets with Gaussian noise to the case of broadly distributed noises. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1109/1109.0497v1.pdf"}
{"id": "1109.1165", "abstract": "  On June 4 2011 the Puyehue-Cordón Caulle volcanic system produced a pyroclastic subplinian eruption reaching level 3 in the volcanic explosivity index. The first stage of the eruption released sand and ashes that affected small towns and cities in the surrounding areas, including San Carlos de Bariloche, in Argentina, one of the largest cities in the North Patagonian andean region. By treating the eruption as a Fermi problem, we estimated the volume and mass of sand ejected as well as the energy and power released during the eruptive phase. We then put the results in context by comparing the obtained values with everyday quantities, like the load of a cargo truck or the electric power produced in Argentina. These calculations have been done as a pedagogic exercise, and after evaluation of the hypothesis was done in the classroom, the calculations have been performed by the students. These are students of the first physics course at the Physics and Chemistry Teacher Programs of the Universidad Nacional de Río Negro. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1109/1109.1165v2.pdf"}
{"id": "1109.4504", "abstract": "  The relation between free carrier absorption and intersubband transitions in semiconductor heterostructures is resolved by comparing a sequence of structures. Our numerical and analytical results show how free carrier absorption evolves from the intersubband transitions in the limit of an infinite number of wells with vanishing barrier width. It is explicitly shown that the integral of the absorption over frequency matches the value obtained by the f-sum rule. This shows that a proper treatment of intersubband transitions is fully sufficient to simulate the entire electronic absorption in heterostructure THz devices. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1109/1109.4504v2.pdf"}
{"id": "1109.4662", "abstract": "  The ATLAS experiment pixel detector upgrade plans are focused on development of new technology, including the FE-I4 readout integrated circuit. The first upgrade project to make use of this new technology is an \"Insertable B-Layer\" (IBL) pixel detector to be installed on a replacement beam pipe in 2013. The IBL will fit inside and not alter the existing ATLAS pixel detector. However, the possibility is being studied to replace the pixel whole detector in 2018 with a lower mass, higher performance instrument based on the FE-I4 chip and new mechanical structures. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1109/1109.4662v1.pdf"}
{"id": "1110.0193", "abstract": "  Electrons floating on the surface of superfluid helium have been suggested as promising mobile spin qubits. Three micron wide channels fabricated with standard silicon processing are filled with superfluid helium by capillary action. Photoemitted electrons are held by voltages applied to underlying gates. The gates are connected as a 3-phase charge-coupled device (CCD). Starting with approximately one electron per channel, no detectable transfer errors occur while clocking 10^9 pixels. One channel with its associated gates is perpendicular to the other 120, providing a CCD which can transfer electrons between the others. This perpendicular channel has not only shown efficient electron transport but also serves as a way to measure the uniformity of the electron occupancy in the 120 parallel channels. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.0193v1.pdf"}
{"id": "1110.1604", "abstract": "  The MicroBooNE experiment is a 170 ton Liquid Argon Time Projection Chamber (LArTPC) that will begin running at Fermilab in 2013. Its primary physics goal is to explore the low energy excess of events seen by the MiniBooNE experiment and it is the next step in the R   D to make LAr a viable option for future large neutrino detectors. This talk presented an overview of the MicroBooNE experiment with an emphasis on the light collection system and recent technical advances. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.1604v1.pdf"}
{"id": "1110.3340", "abstract": "  Understanding the stability of the magnetic field in radiation zones is of crucial importance for various processes in stellar interior like mixing, circulation and angular momentum transport. The stability properties of a star containing a prominent toroidal field in a radiation zone is investigated by means of a linear stability analysis in the Boussinesq approximation taking into account the effect of thermal conductivity. The growth rate of the instability is explicitly calculated and the effects of stable stratification and heat transport are discussed in detail. It is argued that the stabilizing influence of gravity can never entirely suppress the instability caused by electric currents in radiation zones although the stable stratification can significantly decrease the growth rate of instability ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.3340v1.pdf"}
{"id": "1110.3766", "abstract": "  We consider the weak turbulence of whistler waves in the in low-β inner magnetosphere of the Earth. Whistler waves with frequencies, originating in the ionosphere, propagate radially outward and can trigger nonlinear induced scattering by thermal electrons provided the wave energy density is large enough. Nonlinear scattering can substantially change the direction of the wave vector of whistler waves and hence the direction of energy flux with only a small change in the frequency. A portion of whistler waves return to the ionosphere with a smaller perpendicular wave vector resulting in diminished linear damping and enhanced ability to pitch-angle scatter trapped electrons. In addition, a portion of the scattered wave packets can be reflected near the ionosphere back into the magnetosphere. Through multiple nonlinear scatterings and ionospheric reflections a long-lived wave cavity containing turbulent whistler waves can be formed with the appropriate properties to efficiently pitch-angle scatter trapped electrons. The primary consequence on the Earth's radiation belts is to reduce the lifetime of the trapped electron population. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.3766v2.pdf"}
{"id": "1110.4434", "abstract": "  We study radion phenomenology in an warped extra-dimension scenario with Standard Model fields in the bulk, with and without an additional fourth family of fermions. The radion couplings with the fermions will be generically misaligned with respect to the Standard Model fermion mass matrices, therefore producing some amount of flavor violating couplings and potentially influencing production and decay rates of the radion. Simple analytic expressions for the radion-fermion couplings are obtained with three or four families. We also update and analyze the current experimental limits on radion couplings and on the model parameters, again with both three and four families scenarios. We finally present the modified decay branching ratios of the radion with an emphasis on the new channels involving flavor diagonal and flavor violating decays into fourth generation quarks and leptons. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.4434v1.pdf"}
{"id": "1110.4857", "abstract": "  We present a numerical study of the dynamics of the one-dimensional Ising model by applying the large-deviation method to describe ensembles of dynamical trajectories. In this approach trajectories are classified according to a dynamical order parameter and the structure of ensembles of trajectories can be understood from the properties of large-deviation functions, which play the role of dynamical free-energies. We consider both Glauber and Kawasaki dynamics, and also the presence of a magnetic field. For Glauber dynamics in the absence of a field we confirm the analytic predictions of Jack and Sollich about the existence of critical dynamical, or space-time, phase transitions at critical values of the \"counting\" field s. In the presence of a magnetic field the dynamical phase diagram also displays first order transition surfaces. We discuss how these non-equilibrium transitions in the 1d Ising model relate to the equilibrium ones of the 2d Ising model. For Kawasaki dynamics we find a much simple dynamical phase structure, with transitions reminiscent of those seen in kinetically constrained models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.4857v1.pdf"}
{"id": "1110.6711", "abstract": "  It is stated that a class of f(R) gravity models seem to obtain ΛCDM behaviour for high redshifts and general relativistic behaviour locally at high curvatures. In the present paper, we numerically study polytropic configurations that resemble stars like young sun with Hu and Sawicki f(R) gravity field equations and compare the spacetime at the boundary to the general relativistic counterpart. These polytropes are stationary spherically symmetric configurations and have regular metrics at the origin. Since Birkhoff's theorem does not apply for modified gravity, the solution outside may deviate from Schwarzschild-de Sitter spacetime. At the boundary, Post-Newtonian parametrization was used to determine how much the studied model deviates from the general relativistic ΛCDM model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.6711v2.pdf"}
{"id": "1111.0853", "abstract": "  We significantly extend recently developed methods to faithfully reconstruct unknown quantum states that are approximately low-rank, using only a few measurement settings. Our new method is general enough to allow for measurements from a continuous family, and is also applicable to continuous-variable states. As a technical result, this work generalizes quantum compressed sensing to the situation where the measured observables are taken from a so-called tight frame (rather than an orthonormal basis) — hence covering most realistic measurement scenarios. As an application, we discuss the reconstruction of quantum states of light from homodyne detection and other types of measurements, and we present simulations that show the advantage of the proposed compressed sensing technique over present methods. Finally, we introduce a method to construct a certificate which guarantees the success of the reconstruction with no assumption on the state, and we show how slightly more measurements give rise to \"universal\" state reconstruction that is highly robust to noise. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.0853v3.pdf"}
{"id": "1111.0964", "abstract": "  We model recruitment in adaptive social networks in the presence of birth and death processes. Recruitment is characterized by nodes changing their status to that of the recruiting class as a result of contact with recruiting nodes. Only a susceptible subset of nodes can be recruited. The recruiting individuals may adapt their connections in order to improve recruitment capabilities, thus changing the network structure adaptively. We derive a mean field theory to predict the dependence of the growth threshold of the recruiting class on the adaptation parameter. Furthermore, we investigate the effect of adaptation on the recruitment level, as well as on network topology. The theoretical predictions are compared with direct simulations of the full system. We identify two parameter regimes with qualitatively different bifurcation diagrams depending on whether nodes become susceptible frequently (multiple times in their lifetime) or rarely (much less than once per lifetime). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.0964v2.pdf"}
{"id": "1111.1252", "abstract": "  We discuss the extension of loop quantum gravity to topspin networks, a proposal which allows topological information to be encoded in spin networks. We will show that this requires minimal changes to the phase space, C*-algebra and Hilbert space of cylindrical functions. We will also discuss the area and Hamiltonian operators, and show how they depend on the topology. This extends the idea of \"background independence\" in loop quantum gravity to include topology as well as geometry. It is hoped this work will confirm the usefulness of the topspin network formalism and open up several new avenues for research into quantum gravity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.1252v2.pdf"}
{"id": "1111.4048", "abstract": "  A theory is developed to describe the effect of an intrinsic localized mode (ILM) on small vibrations in a monatomic chain with hard quartic anharmonicity. One prediction is the appearance in the chain of linear local modes nearby the ILM. To check this result, MD calculations of vibrations under strong local excitation are carried through with high precision. The results fully confirm the prediction. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.4048v1.pdf"}
{"id": "1111.4167", "abstract": "  Faraday rotation measure synthesis is a method for analyzing multichannel polarized radio emissions, and it has emerged as an important tool in the study of galactic and extra-galactic magnetic fields. The method requires the recovery of the Faraday dispersion function from measurements restricted to limited wavelength ranges, which is an ill-conditioned deconvolution problem. Here, we discuss a recovery method, which assumes a sparse approximation of the Faraday dispersion function in an over-complete dictionary of functions. We discuss the general case, when both thin and thick components are included in the model, and we present the implementation of a greedy deconvolution algorithm. We illustrate the method with several numerical simulations that emphasize the effect of the covered range and sampling resolution in the Faraday depth space, and the effect of noise on the observed data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.4167v1.pdf"}
{"id": "1112.1965", "abstract": "  We introduce a three-dimensional Plebanski action for the gauge group SO(4). In this model, the B field satisfies quadratic simplicity constraints similar to that of the four-dimensional Plebanski theory, but with the difference that the B field is now a one-form. We exhibit a natural notion of \"simple one-form\", and identify a gravitational sector, a topological sector and a degenerate sector in the space of solutions to the simplicity constraints. Classically, in the gravitational sector, the action is shown to be equivalent to that of three-dimensional first order Riemannian gravity. This enables us to perform the complete spin foam quantization of the theory once the simplicity constraints are solved at the classical level, and to compare this result with the various models that have been proposed for the implementation of the constraints after quantization. In particular, we impose the simplicity constraints following the prescriptions of the so-called BC and EPRL models. We observe that the BC prescription cannot lead to the proper vertex amplitude. The EPRL prescription allows to recover the expected result when, in this three-dimensional model, it is supplemented with additional secondary second class constraints. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.1965v2.pdf"}
{"id": "1112.3270", "abstract": "  We provide a short and non-technical summary of our current knowledge and some possible perspectives on the group field theory formalism for quantum gravity, in the form of a (partial) FAQ (with answers). Some of the questions and answers relate to aspects of the formalism that concern loop quantum gravity. This summary also aims at giving a brief, rough guide to the recent literature on group field theory (and tensor models). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.3270v1.pdf"}
{"id": "1112.3830", "abstract": "  In its standard formulation, quantum mechanics presents a very serious inconvenience: given a quantum system, there is no possibility at all to unambiguously (causally) connect a particular feature of its final state with some specific section of its initial state. This constitutes a practical limitation, for example, in numerical analyses of quantum systems, which often make necessary the use of some extra assistance from classical methodologies. Here it is shown how the Bohmian formulation of quantum mechanics removes the ambiguity of quantum mechanics, providing a consistent and clear answer to such a question without abandoning the quantum framework. More specifically, this formulation allows to define probability tubes, along which the enclosed probability keeps constant in time all the way through as the system evolves in configuration space. These tubes have the interesting property that once their boundary is defined at a given time, they are uniquely defined at any time. As a consequence, it is possible to determine final restricted (or partial) probabilities directly from localized sets of (Bohmian) initial conditions on the system initial state. Here, these facts are illustrated by means of two simple yet physically insightful numerical examples: tunneling transmission and grating diffraction. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.3830v2.pdf"}
{"id": "1112.4028", "abstract": "  The dynamics of a vortex dipole in a quasi-two dimensional two-component Bose-Einstein condensate are investigated. A vortex dipole is shown to penetrate the interface between the two components when the incident velocity is sufficiently large. A vortex dipole can also disappear or disintegrate at the interface depending on its velocity and the interaction parameters. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.4028v1.pdf"}
{"id": "1112.6369", "abstract": "  We have performed magnetic susceptibility measurements in Mo_(1-x)Ge_x amorphous thin films biased with an electrical current using anisotropic coils. We tested the symmetry of the vortex response changing the relative orientation between the bias current and the susceptibility coils. We found a region in the DC current - temperature phase diagram where the dynamical vortex structures behave anisotropically. In this region the shielding capability of the superconducting currents measured by the susceptibility coils is less effective along the direction of vortex motion compared to the transverse direction. This anisotropic response is found in the same region where the peak effect in the critical current is developed. On rising temperature the isotropic behavior is recovered. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.6369v1.pdf"}
{"id": "1201.1939", "abstract": "  Simulations have shown that a diverse range of extrasolar terrestrial planet bulk compositions are likely to exist, based on the observed variations in host star elemental abundances. Based on recent studies, it is expected that a significant proportion of host stars may have Mg/Si ratios below 1. Here we examine this previously neglected group of systems. Planets simulated as forming within these systems are found to be Mg-depleted (compared to the Earth), consisting of silicate species such as pyroxene and various feldspars. Planetary carbon abundances also vary in accordance with the host stars C/O ratio. The predicted abundances are in keeping with observations of polluted white dwarfs, lending validity to this approach. Further studies are required to determine the full planetary impacts of the bulk compositions predicted here. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1201/1201.1939v1.pdf"}
{"id": "1201.2226", "abstract": "  We determine the binding energy of the negative positronium ion in the limits of one spatial dimension and of infinitely many dimensions. The numerical result for the one-dimensional ground state energy seems to be a rational number, suggesting the existence of an analytical solution for the wave function. We construct a perturbation expansion around the infinitely-dimensional limit to compute an accurate estimate for the physical three-dimensional case. That result for the energy agrees to five significant figures with variational studies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1201/1201.2226v1.pdf"}
{"id": "1201.5131", "abstract": "  We consider the thermodynamically driven self-assembly of spheres onto the surface of a central sphere. This assembly process forms self-limiting, or terminal, anisotropic clusters (N-clusters) with well defined structures. We use Brownian dynamics to model the assembly of N-clusters varying in size from two to twelve outer spheres, and free energy calculations to predict the expected cluster sizes and shapes as a function of temperature and inner particle diameter. We show that the arrangements of outer spheres at finite temperatures are related to spherical codes, an ideal mathematical sequence of points corresponding to densest possible sphere packings. We demonstrate that temperature and the ratio of the diameters of the inner and outer spheres dictate cluster morphology and dynamics. We find that some N-clusters exhibit collective particle rearrangements, and these collective modes are unique to a given cluster size N. We present a surprising result for the equilibrium structure of a 5-cluster, which prefers an asymmetric square pyramid arrangement over a more symmetric arrangement. Our results suggest a promising way to assemble anisotropic building blocks from constituent colloidal spheres. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1201/1201.5131v1.pdf"}
{"id": "1201.6551", "abstract": "  We consider the problem of estimating the density Π of a determinantal process N from the observation of n independent copies of it. We use an aggregation procedure based on robust testing to build our estimator. We establish non-asymptotic risk bounds with respect to the Hellinger loss and deduce, when n goes to infinity, uniform rates of convergence over classes of densities Π of interest. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1201/1201.6551v2.pdf"}
{"id": "1202.3937", "abstract": "  The concept of oscillatory Universe appears to be realistic and buried in the dynamic dark energy equation of state. We explore its evolutionary history under the frame work of general relativity. We observe that oscillations do not go unnoticed with such an equation of state and that their effects persist later on in cosmic evolution. The `classical' general relativity seems to retain the past history of oscillatory Universe in the form of increasing scale factor as the classical thermodynamics retains this history in the form of increasing cosmological entropy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.3937v3.pdf"}
{"id": "1202.5355", "abstract": "  In this paper, we study the homogeneous one-dimensional bosonic gas interacting via a repulsive contact potential by using the improved Gaussian approximation. We obtain the gapless excitation spectrum of Bogoliubov mode. Our result is in good agreement with the exact numerical calculation based on the Bethe ansatz. We speculate that the improved Gaussian approximation could be a quantitatively good approximation for higher dimensional systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.5355v1.pdf"}
{"id": "1202.5762", "abstract": "  Coloring games are combinatorial games where the players alternate painting uncolored vertices of a graph one of k > 0 colors. Each different ruleset specifies that game's coloring constraints. This paper investigates six impartial rulesets (five new), derived from previously-studied graph coloring schemes, including proper map coloring, oriented coloring, 2-distance coloring, weak coloring, and sequential coloring. For each, we study the outcome classes for special cases and general computational complexity. In some cases we pay special attention to the Grundy function. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.5762v1.pdf"}
{"id": "1203.0250", "abstract": "  The new light-front coupled-cluster (LFCC) method for the nonperturbative solution of Hamiltonian eigenvalue problems is described and then illustrated in an application to quantum electrodynamics. The method eliminates any necessity for a Fock-space truncation and thereby avoids complications associated with such a truncation. An LFCC calculation of the electron's anomalous magnetic moment is formulated for a truncation that, for simplicity, excludes positrons but keeps arbitrarily many photons. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.0250v1.pdf"}
{"id": "1203.2580", "abstract": "  We demonstrate that graphene coating can provide an efficient protection from oxidation by posing a high energy barrier to the path of oxygen atom, which could have penetrated from the top of graphene to the reactive surface underneath. Graphene bilayer, which blocks the diffusion of oxygen with a relatively higher energy barrier provides even better protection from oxidation. While an oxygen molecule is weakly bound to bare graphene surface and hence becomes rather inactive, it can easily dissociates into two oxygen atoms adsorbed to low coordinated carbon atoms at the edges of a vacancy. For these oxygen atoms the oxidation barrier is reduced and hence the protection from oxidation provided by graphene coatings is weakened. Our predictions obtained from the state of the art first-principles calculations of electronic structure, phonon density of states and reaction path will unravel how a graphene can be used as a corrosion resistant coating and guide further studies aiming at developing more efficient nanocoatings. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.2580v1.pdf"}
{"id": "1203.4888", "abstract": "  A quantum mechanical model of two interacting electrons in graphene is considered. We concentrate on the case of zero total momentum of the pair. We show that the dynamics of the system is very unusual. Both stationary and time-dependent problems are considered. It is shown that the complete set of the wave functions with definite energy includes the new functions, previously overlooked. The time evolution of the wave packet, corresponding to the scattering problem setup, leads to the appearance of the localized state at large time. The asymptotics of this state is found analytically. We obtain the lower bound of the life time of this state, which is connected with the breakdown of the continuous model on the lattice scale. The estimate of this bound gives one a hope to observe the localized states in the experiment. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.4888v1.pdf"}
{"id": "1204.3221", "abstract": "  Animals behave adaptively in the environment with multiply competing goals. Understanding of the mechanisms underlying such goal-directed behavior remains a challenge for neuroscience as well for adaptive system research. To address this problem we developed an evolutionary model of adaptive behavior in the multigoal stochastic environment. Proposed neuroevolutionary algorithm is based on neuron's duplication as a basic mechanism of agent's recurrent neural network development. Results of simulation demonstrate that in the course of evolution agents acquire the ability to store the short-term memory and, therefore, use it in behavioral strategies with alternative actions. We found that evolution discovered two mechanisms for short-term memory. The first mechanism is integration of sensory signals and ongoing internal neural activity, resulting in emergence of cell groups specialized on alternative actions. And the second mechanism is slow neurodynamical processes that makes possible to code the previous behavioral choice. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.3221v1.pdf"}
{"id": "1204.3614", "abstract": "  We study the influence of a chaotic environment in the evolution of an open quantum system. We show that there is an inverse relation between chaos and non-Markovianity. In particular, we remark on the deep relation of the short time non-Markovian behavior with the revivals of the average fidelity amplitude-a fundamental quantity used to measure sensitivity to perturbations and to identify quantum chaos. The long time behavior is established as a finite size effect which vanishes for large enough environments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.3614v2.pdf"}
{"id": "1204.3786", "abstract": "  We consider the problem of stochastic comparison of general Garch-like processes, for different parameters and different distributions of the innovations. We identify several stochastic orders that are propagated from the innovations to the Garch process itself, and discuss their interpretations. We focus on the convex order and show that in the case of symmetric innovations it is also propagated to the cumulated sums of the Garch process. More generally, we discuss multivariate comparison results related to the multivariate convex and supermodular order. Finally we discuss ordering with respect to the parameters in the Garch (1,1) case. Key words: Garch, Convex Order, Peakedness, Kurtosis, Supermodularity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.3786v1.pdf"}
{"id": "1204.5523", "abstract": "  The present paper theoretically investigates magnetoresistance curves in quasiperiodic magnetic multilayers for two different growth directions, namely [110] and [100]. We considered identical ferromagnetic layers separated by non-magnetic layers with two different thicknesses chosen based on the Fibonacci sequence. Using parameters for Fe/Cr multilayers, four terms were included in our description of the magnetic energy: Zeeman, cubic anisotropy, bilinear and biquadratic couplings. The minimum energy was determined by the gradient method and the equilibrium magnetization directions found were used to calculate magnetoresistance curves. By choosing spacers with a thickness such that biquadratic coupling is stronger than bilinear coupling, unusual behaviors for the magnetoresistance were observed: (i) for the [110] case there is a different behavior for structures based on even and odd Fibonacci generations; and more interesting, (ii) for the [100] case we found magnetic field ranges for which the magnetoresistance increases with magnetic field. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.5523v1.pdf"}
{"id": "1205.1025", "abstract": "  We report the discovery of 6 SX Phoenicis stars in the southern globular cluster NGC 4833. Images were obtained from January through June 2011 with the Southeastern Association for Research in Astronomy 0.6 meter telescope located at Cerro Tololo Interamerican Observatory. The image subtraction method of Alard     Lupton (1998)was used to search for variable stars in the cluster. We confirmed 17 previously cataloged variables by Demers     Wehlau(1977). In addition to the previously known variables we have identified 10 new variables. Of the total number of confirmed variables in our 10x10 arcmin^2 field, we classified 10 RRab variables, with a mean period of 0.69591 days, 7 RRc, with a mean period of 0.39555 days, 2 possible RRe variables with a mean period of 0.30950 days, a W Ursae Majoris contact binary, an Algol-type binary, and the 6 SX Phoenicis stars with a mean period of 0.05847 days. The periods, relative numbers of RRab and RRc variables, and Bailey diagram are indicative of the cluster being of the Oosterhoff type II. We present the phased-light curves, periods of previously known variables and the periods and classifications of the newly discovered variables, and their location on the color-magnitude diagram. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.1025v1.pdf"}
{"id": "1205.1926", "abstract": "  We propose an algorithm for the efficient parallel implementation of elastoplastic problems with hardening based on the so-called TFETI (Total Finite Element Tearing and Interconnecting) domain decomposition method. We consider an associated elastoplastic model with the von Mises plastic criterion and the linear isotropic hardening law. Such a model is discretized by the implicit Euler method in time and the consequent one time step elastoplastic problem by the finite element method in space. The latter results in a system of nonlinear equations with a strongly semismooth and strongly monotone operator. The semismooth Newton method is applied to solve this nonlinear system. Corresponding linearized problems arising in the Newton iterations are solved in parallel by the above mentioned TFETI domain decomposition method. The proposed TFETI based algorithm was implemented in Matlab parallel environment and its performance was illustrated on a 3D elastoplastic benchmark. Numerical results for different time discretizations and mesh levels are presented and discussed and a local quadratic convergence of the semismooth Newton method is observed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.1926v3.pdf"}
{"id": "1205.2150", "abstract": "  We searched a short-term radio variability in an active galactic nucleus PKS 1510-089. A daily flux monitoring for 143 days at 8.4 GHz was performed, and VLBI observations at 8.4, 22, and 43 GHz were carried out 4 times during the flux monitoring period. As a result, variability with time scale of 20 to 30 days was detected. The variation patterns were well alike on three frequencies, moreover those at 22 and 43 GHz were synchronized. These properties support that this short-term variability is an intrinsic one. The Doppler factor estimated from the variability time scale is 47. Since the Doppler factor is not extraordinary large for AGN, such intrinsic variability with time scale less than 30 days would exist in other AGNs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.2150v1.pdf"}
{"id": "1205.2567", "abstract": "  We present a theoretical analysis of the propagation of light pulses through a medium of four-level atoms, with two strong pump fields and a weak signal field in an N-scheme arrangement. We show that the generation of four-wave mixing has a profound effect on the signal field group velocity and absorption, allowing the signal field propagation to be tuned from superluminal to slow light regimes with amplification. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.2567v1.pdf"}
{"id": "1205.3972", "abstract": "  The propagator of the discrete Schrödinger equation is computed and its properties are revealed through a Feynman path summation in discrete space. Initial data problems such as diffraction in discrete space and continuous time are studied analytically by the application of the new propagator. In the second part of this paper, the analogy between time propagation and 2D scattering by 1D obstacles is explored. New results are given in the context of diffraction by edges within a periodic medium. A connection with tight-binding arrays and photonic crystals is indicated. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.3972v2.pdf"}
{"id": "1206.0546", "abstract": "  When performing asymptotic expansions using the strategy of expansion by regions, it is a non-trivial task to find the relevant regions. The recently published Mathematica code asy.m automates this task, but it has not been able to detect potential regions in threshold expansions or Glauber regions. In this work we present an algorithm and its implementation in the update asy2.m which also reveals potential and Glauber regions automatically. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1206/1206.0546v2.pdf"}
{"id": "1206.1455", "abstract": "  The orbital period of Sco X-1 was first identified by Gottlieb et al. (1975). While this has been confirmed on multiple occasions, this work, based on nearly a century of photographic data, has remained the reference in defining the system ephemeris ever since. It was, however, called into question when Vanderlinde et al. (2003) claimed to find the one-year alias of the historical period in RXTE/ASM data and suggested that this was the true period rather than that of Gottlieb et al. (1975). We examine data from the All Sky Automated Survey (ASAS) spanning 2001-2009. We confirm that the period of Gottlieb et al. (1975) is in fact the correct one, at least in the optical, with the one-year alias strongly rejected by these data. We also provide a modern time of minimum light based on the ASAS data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1206/1206.1455v1.pdf"}
{"id": "1206.2225", "abstract": "  We discuss techniques for accelerating the self consistent field (SCF) iteration for solving the Kohn-Sham equations. These techniques are all based on constructing approximations to the inverse of the Jacobian associated with a fixed point map satisfied by the total potential. They can be viewed as preconditioners for a fixed point iteration. We point out different requirements for constructing preconditioners for insulating and metallic systems respectively, and discuss how to construct preconditioners to keep the convergence rate of the fixed point iteration independent of the size of the atomistic system. We propose a new preconditioner that can treat insulating and metallic system in a unified way. The new preconditioner, which we call an elliptic preconditioner, is constructed by solving an elliptic partial differential equation. The elliptic preconditioner is shown to be more effective in accelerating the convergence of a fixed point iteration than the existing approaches for large inhomogeneous systems at low temperature. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1206/1206.2225v2.pdf"}
{"id": "1206.3229", "abstract": "  We present a GPU parallel implementation of the numeric integration of the Vlasov equation in one spatial dimension based on a second order time-split algorithm with a local modified cubic-spline interpolation. We apply our approach to three different systems with long-range interactions: the Hamiltonian Mean Field, Ring and the self-gravitating sheet models. Speedups and accuracy for each model and different grid resolutions are presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1206/1206.3229v1.pdf"}
{"id": "1206.3530", "abstract": "  The physical relationship between the far-infrared and radio fluxes of star forming galaxies has yet to be definitively determined. The favored interpretation, the \"calorimeter model,\" requires that supernova generated cosmic ray (CR) electrons cool rapidly via synchrotron radiation. However, this cooling should steepen their radio spectra beyond what is observed, and so enhanced ionization losses at low energies from high gas densities are also required. Further, evaluating the minimum energy magnetic field strength with the traditional scaling of the synchrotron flux may underestimate the true value in massive starbursts if their magnetic energy density is comparable to the hydrostatic pressure of their disks. Gamma-ray spectra of starburst galaxies, combined with radio data, provide a less ambiguous estimate of these physical properties in starburst nuclei. While the radio flux is most sensitive to the magnetic field, the GeV gamma-ray spectrum normalization depends primarily on gas density. To this end, spectra above 100 MeV were constructed for two nearby starburst galaxies, NGC 253 and M82, using Fermi data. Their nuclear radio and far-infrared spectra from the literature are compared to new models of the steady-state CR distributions expected from starburst galaxies. Models with high magnetic fields, favoring galaxy calorimetry, are overall better fits to the observations. These solutions also imply relatively high densities and CR ionization rates, consistent with molecular cloud studies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1206/1206.3530v1.pdf"}
{"id": "1209.1057", "abstract": "  We suggest a method for the self-consistent calculations of characteristics of metal films in dielectric environment. Within a modified Kohn-Sham method and stabilized jellium model, the most interesting case of asymmetric metal-dielectric sandwiches is considered, for which dielectric media are different from the two sides of the film. As an example, we focus on Na, Al and Pb. We calculate the spectrum, electron work function, and surface energy of polycrystalline and crystalline films placed into passive isolators. We find that a dielectric environment generally leads to the decrease of both the electron work function and surface energy. It is revealed that the change of the work function is determined only by the average of dielectric constants from both sides of the film. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1209/1209.1057v3.pdf"}
{"id": "1209.3026", "abstract": "  Social media content has grown exponentially in the recent years and the role of social media has evolved from just narrating life events to actually shaping them. In this paper we explore how many resources shared in social media are still available on the live web or in public web archives. By analyzing six different event-centric datasets of resources shared in social media in the period from June 2009 to March 2012, we found about 11", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1209/1209.3026v1.pdf"}
{"id": "1209.5511", "abstract": "  In this letter, we propose a new molecular modulation scheme for nanonetworks. To evaluate the scheme we introduce a more realistic system model for molecule dissemination and propagation processes based on the Poisson distribution. We derive the probability of error of our proposed scheme as well as the previously introduced schemes, including concentration and molecular shift keying modulations by taking into account the error propagation effect of previously decoded symbols. Since in our scheme the decoding of the current symbol does not depend on the previously transmitted and decoded symbols, we do not encounter error propagation; and so as our numerical results indicate, the proposed scheme outperforms the previously introduced schemes. We then introduce a general molecular communication system and use information theoretic tools to derive fundamental limits on its probability of error. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1209/1209.5511v1.pdf"}
{"id": "1210.0467", "abstract": "  Recent overwhelming evidences show that the sun strongly influences the Earth's climate and environment. Moreover existence of life on this Earth mainly depends upon the sun's energy. Hence, understanding of physics of the sun, especially the thermal, dynamic and magnetic field structures of its interior, is very important. Recently, from the ground and space based observations, it is discovered that sun oscillates near 5 min periodicity in millions of modes. This discovery heralded a new era in solar physics and a separate branch called helioseismology or seismology of the sun has started. Before the advent of helioseismology, sun's thermal structure of the interior was understood from the evolutionary solution of stellar structure equations that mimicked the present age, mass and radius of the sun. Whereas solution of MHD equations yielded internal dynamics and magnetic field structure of the sun's interior. In this presentation, I review the thermal, dynamic and magnetic field structures of the sun's interior as inferred by the helioseismology. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.0467v1.pdf"}
{"id": "1210.4643", "abstract": "  Our society has been computerised and globalised due to emergence and spread of information and communication technology (ICT). This enables us to investigate our own socio-economic systems based on large amounts of data on human activities. In this article, methods of treating complexity arising from a vast amount of data, and linking data from different sources, are discussed. Furthermore, several examples are given of studies into the applications of econoinformatics for the Japanese stock exchange, foreign exchange markets, domestic hotel booking data and international flight booking data are shown. It is the main message that spatio-temporal information is a key element to synthesise data from different data sources. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.4643v2.pdf"}
{"id": "1210.7501", "abstract": "  Gravitating bodies significantly alter the flow pattern (density and velocity) of the gas that attempts to stream past. Still, small protoplanets in the Mars–super-Earth range can only bind limited amounts of nebular gas; until the so-called critical core mass has been reached ( 1-10 Earth masses) this gas is in near hydrostatic equilibrium with the nebula. Here we aim for a general description of the flow pattern surrounding these low-mass, embedded planets. Using various simplifying assumptions (subsonic, 2D, inviscid flow, etc), we reduce the problem to a partial differential equation that we solve numerically as well as approximate analytically. It is found that the boundary between the atmosphere and the nebula gas strongly depends on the value of the disc headwind (deviation from Keplerian rotation). With increasing headwind the atmosphere decreases in size and also becomes more asymmetrical. Using the derived flow pattern for the gas, trajectories of small solid particles, which experience both gas drag and gravitational forces, are integrated numerically. Accretion rates for small particles (dust) are found to be low, as they closely follow the streamlines, which curl away from the planet. However, pebble-size particles achieve large accretion rates, in agreement with previous numerical and analytical works. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.7501v1.pdf"}
{"id": "1211.1534", "abstract": "  We examine the performance of a TPC as a gamma-ray telescope above the pair-creation threshold. The contributions to the photon angular resolution are studied and their dependence on energy is obtained. The effective area per detector unit mass for such a thin detector is the conversion mass attenuation coefficient. The differential sensitivity for the detection of a point-like source is then derived. Finally, the measurement of track momentum from deflections due to multiple scattering is optimized.   These analytical results are exemplified numerically for a few sets of detector parameters. TPCs show an impressive improvement in sensitivity with respect to existing pair-creation-based telescopes in the [MeV - GeV] energy range, even with the modest detector parameters of this study. In addition, gas TPCs allow an improvement in angular resolution of about one order of magnitude. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.1534v1.pdf"}
{"id": "1211.2143", "abstract": "  Disclination lines in nematic liquid crystals can exist in different geometric conformations, characterised by their director profile. In certain confined, colloidal and even more prominently in chiral nematics, the director profile may vary along the disclination line. We construct a robust geometric decomposition of director profile variations in closed disclination loops based on a quaternion description and use it to apply topological classification to linked loops with arbitrary variation of the profile. The description bridges the gap between the known abstract classification scheme derived from homotopy theory and the observable local features of disclinations. We compare the resulting decomposition of disclination loop features to a similar decomposition of nematic textures on closed surfaces. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.2143v1.pdf"}
{"id": "1211.2357", "abstract": "  We present a protocol for measuring Bohmian - or the mathematically equivalent hydrodynamic - velocities based on an ensemble of two position measurements, defined from a Positive Operator Valued Measure, separated by a finite time interval. The protocol is very accurate and robust as long as the first measurement uncertainty divided by the finite time interval between measurements is much larger than the Bohmian velocity, and the system evolves under flat potential between measurements. The difference between the Bohmian velocity of the unperturbed state and the measured one is predicted to be much smaller than 1", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.2357v2.pdf"}
{"id": "1211.3012", "abstract": "  In this paper we discuss wild embeddings like Alexanders horned ball and relate them to fractal spaces. We build a C^⋆-algebra corresponding to a wild embedding. We argue that a wild embedding is the result of a quantization process applied to a tame embedding. Therefore quantum states are directly the wild embeddings. Then we give an example of a wild embedding in the 4-dimensional spacetime. We discuss the consequences for cosmology. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.3012v1.pdf"}
{"id": "1211.3198", "abstract": "  With the progress of increasingly precise measurements on the neutrino mixing angles, phenomenological relations such as quark-lepton complementarity (QLC) among mixing angles of quarks and leptons and self-complementarity (SC) among lepton mixing angles have been observed. Using the latest global fit results of the quark and lepton mixing angles in the standard Chau-Keung scheme, we calculate the mixing angles and CP-violating phases in the other eight different schemes. We check the dependence of these mixing angles on the CP-violating phases in different phase schemes. The dependence of QLC and SC relations on the CP phase in the other eight schemes is recognized and then analyzed, suggesting that measurements on CP-violating phases of the lepton sector are crucial to the explicit forms of QLC and SC in different schemes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.3198v2.pdf"}
{"id": "1211.5862", "abstract": "  With computer simulations of the hard sphere model, we examine in detail the microscopic pathway connecting the metastable melt to the emergence of crystalline clusters. In particular we will show that the nucleation of the solid phase does not follow a two-step mechanism, where crystals form inside dense precursor regions. On the contrary, we will show that nucleation is driven by fluctuations of orientational order, and not by the density fluctuations. By considering the development of the pair-excess entropy inside crystalline nuclei, we confirm that orientational order precedes positional order. These results are at odd with the idea of a two-step nucleation mechanism for fluids without a metastable liquid-liquid phase separation. Our study suggests the pivotal role of bond orientational ordering in triggering crystal nucleation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.5862v1.pdf"}
{"id": "1212.0573", "abstract": "  We present a numerical method of analyzing possibly singular incompressible 3D Euler flows using massively parallel high-resolution adaptively refined numerical simulations up to 8192^3 mesh points. Geometrical properties of Lagrangian vortex line segments are used in combination with analytical non-blowup criteria by Deng et al [Commun. PDE 31 (2006)] to reliably distinguish between singular and near-singular flow evolution. We then apply the presented technique to a class of high-symmetry initial conditions and present numerical evidence against the formation of a finite-time singularity in this case. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1212/1212.0573v1.pdf"}
{"id": "1212.2250", "abstract": "  It has recently been shown that there is a close correlation between the slowdown rates and the pulse shapes of six pulsars, and between the slowdown rates and the flux density of three others. This indicates that these phenomena are related by changes in the current flows in the pulsar magnetospheres. In this paper we review the observational status of these studies, which have now been extended to a total of 16 pulsars having correlated slowdown and pulse emission properties. The changes seem to be due to sudden switching between just two discrete magnetospheric states in the well-known processes of mode-changing and pulse nulling. We also address how widespread these phenomena are in the wider pulsar population. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1212/1212.2250v1.pdf"}
{"id": "1212.3082", "abstract": "  The Planck collaboration has recently published precise and resolved measurements of the Sunyaev-Zel'dovich effect in Abell 1656 (the Coma cluster of galaxies), so directly gauging the electron pressure profile in the intracluster plasma. On the other hand, such a quantity may be also derived from combining the density and temperature provided by X-ray observations of the thermal bremsstrahlung radiation emitted by the plasma. We find a model-independent tension between the SZ and the X-ray pressure, with the SZ one being definitely lower by 15-20", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1212/1212.3082v1.pdf"}
{"id": "1212.6415", "abstract": "  Three core-softened families of potentials are checked for the presence of density and diffusion anomalies. These potentials exhibit a repulsive core with a softening region and at larger distances an attractive well. We found that the region in the pressure-temperature phase diagram in which the anomalies are present increases if the slope between the core-softened scale and the attractive part of the potential decreases. The anomalous region also increases if the range of the core-softened or of the attractive part of the potential decreases. We also show that the presence of the density anomaly is consistent with the non monotonic changes of the radial distribution function at each one of the two scales when temperature and density are varied. Then, using this anomalous behavior of the structure we show that the pressures and the temperatures in which the radial distribution functions of the two length scales are equal are identified with the Widom line. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1212/1212.6415v1.pdf"}
{"id": "1301.0262", "abstract": "  We use the formalism of Geometrothermodynamics to describe chemical reactions in the context of equilibrium thermodynamics. Any chemical reaction in a closed system is shown to be described by a geodesic in a 2-dimensional manifold that can be interpreted as the equilibrium space of the reaction. We first show this in the particular cases of a reaction with only two species corresponding to either two ideal gases or two van der Waals gases. We then consider the case of a reaction with an arbitrary number of species. The initial equilibrium state of the geodesic is determined by the initial conditions of the reaction. The final equilibrium state, which follows from a thermodynamic analysis of the reaction, is shown to correspond to a coordinate singularity of the thermodynamic metric which describes the equilibrium manifold. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.0262v1.pdf"}
{"id": "1301.2944", "abstract": "  We investigate the Watts-Strogatz network with the clustering coefficient C dependent on the rewiring probability. The network is an area of two opposite contact processes, where nodes can be in two states, S or D. One of the processes is governed by the Sznajd dynamics: if there are two connected nodes in D-state, all their neighbors become D with probability p. For the opposite process it is sufficient to have only one neighbor in state S; this transition occurs with probability 1. The concentration of S-nodes changes abruptly at given value of the probability p. The result is that for small p, in clusterized networks the activation of S nodes prevails. This result is explained by a comparison of two limit cases: the Watts-Strogatz network without rewiring, where C=0.5, and the Bethe lattice where C=0. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.2944v2.pdf"}
{"id": "1301.5012", "abstract": "  Densely-packed bundles of biological filaments (filamentous proteins) are common and critical structural elements in range of biological materials. While most bundles form from intrinsically straight filaments, there are notable examples of protein filaments possessing a natural, or intrinsic, curvature, such as the helical bacterial flagellum. We study the non-linear interplay between thermodynamic preference for dense and regular inter-filament packing and the mechanical preference for uniform filament shape in bundles of helically-curved filaments. Geometric constraints in bundles make perfect inter-filament (constant spacing, or isometric) packing incompatible with perfect intra-filament (constant shape, or isomorphic) packing. As a consequence, we predict that bundle packing exhibits a strong sensitivity to bundle size, evolving from the isometric packing at small radii to an isomorphic packing at large radii. The nature of the transition between these extremal states depends on thermodynamic costs of packing distortion, with packing in elastically-constrained bundles evolving smoothly with size, while packing in osmotically-compressed bundles may exhibit a singular transition from the isometric packing at a finite bundle radius. We consider the equilibrium assembly of bundles in a saturated solution of filaments and show that mechanical cost of isomorphic packing leads to self-limited equilibrium bundle diameters, whose size and range of thermodynamic stability depend both on condensation mechanism, as well as the helical geometry of filaments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.5012v1.pdf"}
{"id": "1301.7420", "abstract": "  We study the proximity effect in a topological nanowire tunnel coupled to an s-wave superconducting substrate. We use a general Green's function approach that allows us to study the evolution of the Andreev bound states in the wire into Majorana fermions. We show that the strength of the tunnel coupling induces a topological transition in which the Majorana fermionic states can be destroyed when the coupling is very strong. Moreover, we provide a phenomenologial study of the effects of disorder in the superconductor on the formation of Majorana fermions. We note a non-trivial effect of a quasiparticle broadening term which can take the wire from a topological into a non-topological phase in certain ranges of parameters. Our results have also direct consequences for a nanowire coupled to an inhomogenous superconductor. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.7420v4.pdf"}
{"id": "1302.0481", "abstract": "  We study the problem of diffusing particles which coalesce upon contact. With the aid of a non-perturbative renormalization group, we first analyze the dynamics emerging below the critical dimension two, where strong fluctuations imply anomalously slow decay. Above two dimensions, the long-time, low-density behavior is known to conform with the law of mass action. For this case, we establish an exact mapping between the physics at the microscopic scale (lattice structure, particle shape and size) and the macroscopic decay rate in the law of mass action. In addition, we identify a term violating this classical law. It originates in long-range and many-particle fluctuations and is a simple, universal function of the macroscopic decay rate. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1302/1302.0481v1.pdf"}
{"id": "1302.3902", "abstract": "  NEXT-100 is an electroluminescent high pressure Time Projection Chamber currently under construction. It will search for the neutrino-less double beta decay in 136Xe at the Canfranc Underground Laboratory. NEXT-100 aims to achieve nearly intrinsic energy resolution and to highly suppress background events by taking advantage of the unique properties of xenon in the gaseous phase as the detection medium. In order to prove the principle of operation and to study which are the best operational conditions, two prototypes were constructed: NEXT-DEMO and NEXT-DBDM. In this paper we present the latest results from both prototypes. We report the improvement in terms of light collection (? 3x?) achieved by coating the walls of NEXT-DEMO with tetraphenyl butadiene (TPB), the outstanding energy resolution of 1 ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1302/1302.3902v1.pdf"}
{"id": "1303.3636", "abstract": "  This paper proposes a new adaptive algorithm for the implementation of the linearly constrained minimum variance (LCMV) beamformer. The proposed algorithm utilizes the set-membership filtering (SMF) framework and the reduced-rank joint iterative optimization (JIO) scheme. We develop a stochastic gradient (SG) based algorithm for the beamformer design. An effective time-varying bound is employed in the proposed method to adjust the step sizes, avoid the misadjustment and the risk of overbounding or underbounding. Simulations are performed to show the improved performance of the proposed algorithm in comparison with existing full-rank and reduced-rank methods. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1303/1303.3636v1.pdf"}
{"id": "1304.2954", "abstract": "  We present a scheme for full quantum state tomography tailored for two spin qubits in a double quantum dot. A set of 15 quantum states allows to determine the density matrix in this two-qubit space by projective measurement. In this paper we choose a set gained from mutually unbiased bases. We determine how those 15 projections can be represented by charge measurements after a spin-to-charge conversion and the application of quantum gates. The quantum gates include exchange-based gates as well as rotations by electron spin resonance (ESR). We assume the experimental realization of ESR operations to be more difficult than the exchange gate operation. Therefore, it is an important result that the ESR gates are limited by a pi/2 rotation for one of the electron spins per measurement. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.2954v1.pdf"}
{"id": "1304.4041", "abstract": "  Accurate detection of mitosis plays a critical role in breast cancer histopathology. Manual detection and counting of mitosis is tedious and subject to considerable inter- and intra-reader variations. Multispectral imaging is a recent medical imaging technology, proven successful in increasing the segmentation accuracy in other fields. This study aims at improving the accuracy of mitosis detection by developing a specific solution using multispectral and multifocal imaging of breast cancer histopathological data. We propose to enable clinical routine-compliant quality of mitosis discrimination from other objects. The proposed framework includes comprehensive analysis of spectral bands and z-stack focus planes, detection of expected mitotic regions (candidates) in selected focus planes and spectral bands, computation of multispectral spatial features for each candidate, selection of multispectral spatial features and a study of different state-of-the-art classification methods for candidates classification as mitotic or non mitotic figures. This framework has been evaluated on MITOS multispectral medical dataset and achieved 60", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.4041v1.pdf"}
{"id": "1304.4148", "abstract": "  We investigate tidal dissipation of obliquity in hot Jupiters. Assuming an initial random orientation of obliquity and parameters relevant to the observed population, the obliquity of hot Jupiters does not evolve to purely aligned systems. In fact, the obliquity evolves to either prograde, retrograde or 90^o orbits where the torque due to tidal perturbations vanishes. This distribution is incompatible with observations which show that hot jupiters around cool stars are generally aligned. This calls into question the viability of tidal dissipation as the mechanism for obliquity alignment of hot Jupiters around cool stars. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.4148v1.pdf"}
{"id": "1304.5115", "abstract": "  The results of a Monte Carlo simulation study of the hadron energy response for the magnetized Iron CALorimeter detector, ICAL, proposed to be located at the India-based Neutrino Observatory (INO) is presented. Using a GEANT4 modeling of the detector ICAL, interactions of atmospheric neutrinos with target nuclei are simulated. The detector response to hadrons propagating through it is investigated using the hadron hit multiplicity in the active detector elements. The detector response to charged pions of fixed energy is studied first, followed by the average response to the hadrons produced in atmospheric neutrino interactions using events simulated with the NUANCE event generator. The shape of the hit distribution is observed to fit the Vavilov distribution, which reduces to a Gaussian at high energies. In terms of the parameters of this distribution, we present the hadron energy resolution as a function of hadron energy, and the calibration of hadron energy as a function of the hit multiplicity. The energy resolution for hadrons is found to be in the range 85", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.5115v2.pdf"}
{"id": "1304.8023", "abstract": "  A collider probe of the radiative seesaw models are considered. Two key ingredients of these models, the extended Higgs sector and the source of the Majorana mass, although these details differ model by model, would be studied at the TeV-scale electron-positron and electron-electron colliders. The searches and mass determinations in the inert doublet model, which is the extended Higgs sector of the Ma model, are summarized as an example. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.8023v1.pdf"}
{"id": "1304.8072", "abstract": "  This paper presents a new formulation for trailing edge noise radiation from rotating blades based on an analytical solution of the convective wave equation. It accounts for distributed loading and the effect of mean flow and spanwise wavenumber. A commonly used theory due to Schlinker and Amiet (1981) predicts trailing edge noise radiation from rotating blades. However, different versions of the theory exist; it is not known which version is the correct one and what the range of validity of the theory is. This paper addresses both questions by deriving Schlinker and Amiet's theory in a simple way and by comparing it to the new formulation, using model blade elements representative of a wind turbine, a cooling fan and an aircraft propeller. The correct form of Schlinker and Amiet's theory (1981) is identified. It is valid at high enough frequency, i.e. for a Helmholtz number relative to chord greater than one and a rotational frequency much smaller than the angular frequency of the noise sources. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.8072v2.pdf"}
{"id": "1305.1342", "abstract": "  We investigate some basic scenarios in which a given set of bipartite quantum states may consistently arise as the set of reduced states of a global N-partite quantum state. Intuitively, we say that the multipartite state \"joins\" the underlying correlations. Determining whether, for a given set of states and a given joining structure, a compatible N-partite quantum state exists is known as the quantum marginal problem. We restrict to bipartite reduced states that belong to the paradigmatic classes of Werner and isotropic states in d dimensions, and focus on two specific versions of the quantum marginal problem which we find to be tractable. The first is Alice-Bob, Alice-Charlie joining, with both pairs being in a Werner or isotropic state. The second is m-n sharability of a Werner state across N subsystems, which may be seen as a variant of the N-representability problem to the case where subsystems are partitioned into two groupings of m and n parties, respectively. By exploiting the symmetry properties that each class of states enjoys, we determine necessary and sufficient conditions for three-party joinability and 1-n sharability for arbitrary d. Our results explicitly show that although entanglement is required for sharing limitations to emerge, correlations beyond entanglement generally suffice to restrict joinability, and not all unentangled states necessarily obey the same limitations. The relationship between joinability and quantum cloning as well as implications for the joinability of arbitrary bipartite states are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.1342v3.pdf"}
{"id": "1305.3105", "abstract": "  Context-consistency checking is challenging in the dynamic and uncertain ubiquitous computing environments. This is because contexts are often noisy owing to unreliable sensing data streams, inaccurate data measurement, fragile connectivity and resource constraints. One of the state-of-the-art efforts is CEDA, which concurrently detects context consistency by exploring the happened-before relation among events. However, CEDA is seriously limited by several side effects — centralized detection manner that easily gets down the checker process, heavy computing complexity and false negative.   In this paper, we propose SECA: Snapshot-based Event Detection for Checking Asynchronous Context Consistency in ubiquitous computing. SECA introduces snapshot-based timestamp to check event relations, which can detect scenarios where CEDA fails. Moreover, it simplifies the logical clock instead of adopting the vector clock, and thus significantly reduces both time and space complexity. Empirical studies show that SECA outperforms CEDA in terms of detection accuracy, scalability, and computing complexity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.3105v1.pdf"}
{"id": "1305.3217", "abstract": "  The extended high-energy gamma-ray (>100 MeV) emission occurred after the prompt gamma-ray bursts (GRBs) is usually characterized by a single power-law spectrum, which has been explained as the afterglow synchrotron radiation. The afterglow inverse-Compton emission has long been predicted to be able to produce a high-energy component as well, but previous observations have not revealed such a signature clearly, probably due to the small number of >10 GeV photons even for the brightest GRBs known so far. In this Letter, we report on the Fermi Large Area Telescope (LAT) observations of the >100 MeV emission from the very bright and nearby GRB 130427A. We characterize the time-resolved spectra of the GeV emission from the GRB onset to the afterglow phase. By performing time-resolved spectral fits of GRB 130427A, we found a strong evidence of an extra hard spectral component that exists in the extended high-energy emission of this GRB. We argue that this hard component may arise from the afterglow inverse Compton emission. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.3217v2.pdf"}
{"id": "1305.4196", "abstract": "  This article introduces a highly parallel algorithm for molecular dynamics simulations with short-range forces on single node multi- and many-core systems. The algorithm is designed to achieve high parallel speedups for strongly inhomogeneous systems like nanodevices or nanostructured materials. In the proposed scheme the calculation of the forces and the generation of neighbor lists is divided into small tasks. The tasks are then executed by a thread pool according to a dependent task schedule. This schedule is constructed in such a way that a particle is never accessed by two threads at the same time.Benchmark simulations on a typical 12 core machine show that the described algorithm achieves excellent parallel efficiencies above 80 ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.4196v3.pdf"}
{"id": "1305.4691", "abstract": "  A hole in a two-dimensional Ising antiferromagnet was believed to be infinitely heavy due to the string of wrongly oriented spins it creates as it moves, which should trap it near its original location. Trugman showed that, in fact, the hole acquires a finite effective mass due to contributions from so-called Trugman loop processes, where the hole goes nearly twice around closed loops, first creating and then removing wrongly-oriented spins, and ending up at a different lattice site. This generates effective second- and third-nearest-neighbor hopping terms which keep the quasiparticle on the sublattice it was created on. Here, we investigate the trapping of the quasiparticle near a single attractive non-magnetic impurity placed at one lattice site. We consider the two cases with the quasiparticle and impurity being on the same versus on different sublattices. The main result is that even though the quasiparticle can not see the bare disorder in the latter case, the coupling to magnons generates an effective renormalized disorder on its own sublattice which is strong enough to lead to bound states, which however have a very different spectrum than when the quasiparticle and impurity are on the same sublattice. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.4691v2.pdf"}
{"id": "1305.4925", "abstract": "  We show that for a special alternating link diagram, the following three polynomials are essentially the same: a) the part of the HOMFLY polynomial that corresponds to the leading term in the Alexander polynomial; b) the h-vector for a triangulation of the root polytope of the Seifert graph and c) the enumerator of parking functions for the planar dual of the Seifert graph. These observations yield formulas for the maximal z-degree part of the HOMFLY polynomial of an arbitrary homogeneous link as well. Our result is part of a program aimed at reading HOMFLY coefficients out of Heegaard Floer homology. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.4925v1.pdf"}
{"id": "1305.5985", "abstract": "  Phase randomization is a very important assumption in the Bennett-Brassard 1984 quantum key distribution (QKD) system with a weak coherent source. Thus an active phase modulator is needed to randomize the phase of source. However, it is hard to check whether the phase of source is randomized totally or not in practical QKD systems. In this paper a partially random phase attack is proposed to exploit this imperfection. Our analysis shows that Eve can break the security of a two-way QKD system by using our attack, even if an active phase randomization is adopted by Alice. Furthermore, the numerical simulation shows that in some parameter regimes, our attack is immune to the one-decoy-state method. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.5985v1.pdf"}
{"id": "1306.5958", "abstract": "  We investigate the possibility that the primordial perturbation has two sources: the inflaton and a spectator field, which is not dynamically important during inflation but which after inflation can contribute to the curvature perturbation. The recent Planck results on the power spectrum and non-Gaussianity allow us to put constraints on such mixed models. In the generic case, where no specific model for the inflaton or the spectator is assumed, one finds that in the mixed scenario it is possible to have a large trispectrum with tau_NL >> (f_NL)^2. The constraints on inflation models in the plane of the spectral index and tensor-to-scalar ratio are modified by the presence of a spectator and depend also on the ratio of the spectator-to-inflaton power R. If one chooses the spectator to be the curvaton with a quadratic potential, non-Gaussianities can be computed and imply restrictions on possible values of R. We also consider a mixed curvaton and chaotic inflation model and show that even quartic chaotic inflation is still feasible in the context of mixed models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.5958v1.pdf"}
{"id": "1306.6084", "abstract": "  In the works of K.A. Pericak-Spector and S. Spector <cit.> a class of self-similar solutions are constructed for the equations of radial isotropic elastodynamics that describe cavitating solutions. Cavitating solutions decrease the total mechanical energy and provide a striking example of non-uniqueness of entropy weak solutions (for polyconvex energies) due to point-singularities at the cavity. To resolve this paradox, we introduce the concept of singular limiting induced from continuum solution (or slic-solution), according to which a discontinuous motion is a slic-solution if its averages form a family of smooth approximate solutions to the problem. It turns out that there is an energetic cost for creating the cavity, which is captured by the notion of slic-solution but neglected by the usual entropic weak solutions. Once this cost is accounted for, the total mechanical energy of the cavitating solution is in fact larger than that of the homogeneously deformed state. We also apply the notion of slic-solutions to a one-dimensional example describing the onset of fracture, and to gas dynamics in Langrangean coordinates with Riemann data inducing vacuum in the wave fan. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.6084v1.pdf"}
{"id": "1307.0137", "abstract": "  A general method for compressing the modulation time-bandwidth product of analog signals is introduced and experimentally demonstrated. As one of its applications, this physics-based signal grooming performs feature-selective stretch, enabling a conventional digitizer to capture fast temporal features that were beyond its bandwidth. At the same time, the total digital data size is reduced. The compression is lossless and is achieved through a same-domain transformation of the signal's complex field, performed in the analog domain prior to digitization. Our method is inspired by operation of Fovea centralis in the human eye and by anamorphic transformation in visual arts. The proposed transform can also be performed in the digital domain as a digital data compression algorithm to alleviate the storage and transmission bottlenecks associated with \"big data\". ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.0137v4.pdf"}
{"id": "1307.0233", "abstract": "  Investigation of the interfacial electronic properties of N,N'-bis(n-octyl)-(1,7   1,6)-dicyanoperylene-3,4:9,10-bisdicarboximide (PDI8-CN2) organic semiconductor films grown on silicon dioxide is performed by polarization-resolved second harmonic generation optical spectroscopy, pointing out a spatial region where charge carriers distribution in the semiconductor lacks inversion symmetry. By developing a model for nonlinear susceptibility in the framework of Debye-Huckel screening theory, we show that the experimental findings can be interpreted as resulting from the presence of a net charge localized at the silicon dioxide, accompanied by a non-uniform charge distribution in the organic semiconductor. Photoluminescence analysis further reinforces this scenario. Reduction-oxidation reactions involving PDI8-CN2 and water molecules are invoked as physical origin of the localized charge. The work outlines a sensitive tool to probe the total charge localized at buried semiconductor/dielectric interfaces in organic thin-film transistors without resorting to invasive contact-based analyses. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.0233v1.pdf"}
{"id": "1307.1375", "abstract": "  We propose a way to implement a three-qubit refined Deutsh-Jozsa (DJ) algorithm. The present proposal is based on the construction of the 35 f-controlled phase gates, which uses single-qubit σ_z gates and two-qubit standard controlled-phase (CP) gates only. This proposal is implementable because a single-qubit σ_z gate can be easily realized by applying a single classical pulse and a two-qubit CP gate has been experimentally demonstrated in various physical systems. Finally, it is noted that this proposal is quite general, and can be applied to implement a three-qubit refined DJ algorithm in a cavity-based or noncavity-based physical system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.1375v1.pdf"}
{"id": "1307.1855", "abstract": "  We investigate an attractive Bose-Einstein condensate in two coupled one dimensional channels. In this system a stable double channel soliton can be formed. It is symmetric for small interaction parameters and asymmetric for large ones. We study this symmetry breaking phenomenon in detail. Next, we investigate the dynamics of symmetric double channel soliton collisions. For sufficiently strong interactions we observe spontaneous symmetry breaking during the collision. Approximate considerations based on two different methods, Bogoliubov and variational, are used to describe this effect. The results are compatible. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.1855v1.pdf"}
{"id": "1307.2245", "abstract": "  The unique ghost-free mass and nonlinear potential terms for general relativity are presented in a diffeomorphism and local Lorentz invariant vierbein formalism. This construction requires an additional two-index Stuckelberg field, beyond the four scalar fields used in the metric formulation, and unveils a new local SL(4) symmetry group of the mass and potential terms, not shared by the Einstein-Hilbert term. The new field is auxiliary but transforms as a vector under two different Lorentz groups, one of them the group of local Lorentz transformations, the other an additional global group. This formulation enables a geometric interpretation of the mass and potential terms for gravity in terms of certain volume forms. Furthermore, we find that the decoupling limit is much simpler to extract in this approach; in particular, we are able to derive expressions for the interactions of the vector modes. We also note that it is possible to extend the theory by promoting the two-index auxiliary field into a Nambu-Goldstone boson nonlinearly realizing a certain space-time symmetry, and show how it is \"eaten up\" by the antisymmetric part of the vierbein. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.2245v2.pdf"}
{"id": "1307.3938", "abstract": "  Earth's magnetic field is generated by processes in the electrically conducting, liquid outer core, subsumed under the term `geodynamo'. In the last decades, great effort has been put into the numerical simulation of core dynamics following from the magnetohydrodynamic (MHD) equations. However, the numerical simulations are far from Earth's core in terms of several control parameters. Different scaling analyses found simple scaling laws for quantities like heat transport, flow velocity, magnetic field strength and magnetic dissipation time.   We use an extensive dataset of 116 numerical dynamo models compiled by Christensen and co-workers to analyse these scalings from a rigorous model selection point of view. Our method of choice is leave-one-out cross-validation which rates models according to their predictive abilities. In contrast to earlier results, we find that diffusive processes are not negligible for the flow velocity and magnetic field strength in the numerical dynamos. Also the scaling of the magnetic dissipation time turns out to be more complex than previously suggested. Assuming that the processes relevant in the numerical models are the same as in Earth's core, we use this scaling to estimate an Ohmic dissipation of 3-8 TW for the core. This appears to be consistent with recent high CMB heat flux scenarios. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.3938v1.pdf"}
{"id": "1307.4146", "abstract": "  Physical layer security is an emerging technique to improve the wireless communication security, which is widely regarded as a complement to cryptographic technologies. To design physical layer security techniques under practical scenarios, the uncertainty and imperfections in the channel knowledge need to be taken into consideration. This paper provides a survey of recent research and development in physical layer security considering the imperfect channel state information (CSI) at communication nodes. We first present an overview of the main information-theoretic measures of the secrecy performance with imperfect CSI. Then, we describe several signal processing enhancements in secure transmission designs, such as secure on-off transmission, beamforming with artificial noise, and secure communication assisted by relay nodes or in cognitive radio systems. The recent studies of physical layer security in large-scale decentralized wireless networks are also summarized. Finally, the open problems for the on-going and future research are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.4146v2.pdf"}
{"id": "1307.4887", "abstract": "  We have carried out JHK_s imaging of 12 white dwarf debris disk candidates from the WIRED SDSS DR7 catalog, aiming to confirm or rule out disks among these sources. On the basis of positional identification and the flux density spectra, we find that seven white dwarfs have excess infrared emission, but mostly at WISE W1 and W2 bands, four are due to nearby red objects consistent with background galaxies or very low mass dwarfs, and one exhibits excess emission at JHK_s consistent with an unresolved L0 companion at the correct distance. While our photometry is not inconsistent with all seven excesses arising from disks, the stellar properties are distinct from the known population of debris disk white dwarfs, making the possibility questionable. In order to further investigate the nature of these infrared sources, warm Spitzer imaging is needed, which may help resolve galaxies from the white dwarfs and provide more accurate flux measurements. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.4887v2.pdf"}
{"id": "1308.1209", "abstract": "  The continuous-time quantum Monte Carlo method is applied to the interacting resonant level model (IRLM) using double expansion with respect to Coulomb interaction Ufc and hybridization V. Thermodynamics of the IRLM without spin is equivalent to the anisotropic Kondo model in the low-energy limit. Exact dynamics and thermodynamics of the IRLM are derived numerically for a wide range of Ufc with a given value of V. For negative Ufc, excellent agreement including a quantum critical point is found with a simple scaling formula that deals with V in the lowest-order, and Ufc up to infinite order. As Ufc becomes positive and large, lower order scaling results deviate from exact numerical results. Possible relevance of the results is discussed to certain Samarium compounds with unusual heavy-fermion behavior. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.1209v1.pdf"}
{"id": "1308.4184", "abstract": "  In the Jupiter-Io system, the moon's motion produces currents along the field lines that connect it to Jupiter's polar regions. The currents generate, and modulate radio emissions along their paths via the electron-cyclotron maser instability. Based on this process, we suggest that such modulation of planetary radio emissions may reveal the presence of exomoons around giant planets in exoplanetary systems. A model explaining the modulation mechanism in the Jupiter-Io system is extrapolated, and used to define criteria for exomoon detectability. A cautiously optimistic scenario of possible detection of such exomoons around Epsilon Eridani b, and Gliese 876 b is provided. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.4184v4.pdf"}
{"id": "1309.1469", "abstract": "  We present a novel, general-purpose method for deconvolving and denoising images from gridded radio interferometric visibilities using Bayesian inference based on a Gaussian process model. The method automatically takes into account incomplete coverage of the uv-plane, signal mode coupling due to the primary beam, and noise mode coupling due to uv sampling. Our method uses Gibbs sampling to efficiently explore the full posterior distribution of the underlying signal image given the data. We use a set of widely diverse mock images with a realistic interferometer setup and level of noise to assess the method. Compared to results from a proxy for point source- based CLEAN method we find that in terms of RMS error and signal-to-noise ratio our approach performs better than traditional deconvolution techniques, regardless of the structure of the source image in our test suite. Our implementation scales as O(np log np), provides full statistical and uncertainty information of the reconstructed image, requires no supervision, and provides a robust, consistent framework for incorporating noise and parameter marginalizations and foreground removal. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.1469v2.pdf"}
{"id": "1309.2235", "abstract": "  The mechanism of extraction of information stored in a quantum memory is studied here in detail. We consider memories containing a single excitation of a collective atomic state, which is mapped into a single photon during the reading process. A theory is developed for the wavepacket of the extracted photon, leading to a simple analytical expression depending on the key parameters of the problem, like detuning and intensity of the read field and the number of atoms in the atomic ensemble. This theory is then compared to a large set of experimental situations and a satisfactory quantitative agreement is obtained. In this way, we are able to systematically study the saturation and spectrum of the reading process, as well as clarify the role of superradiance in the system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.2235v1.pdf"}
{"id": "1309.5270", "abstract": "  We address the non-Markovian character of quantum maps describing the interaction of a qubit with a random classical field. In particular, we evaluate trace- and capacity-based non-Markovianity measures for two relevant classes of environments showing non-Gaussian fluctuations, described respectively by random telegraph noise and colored noise with spectra of the the form 1/f^α. We analyze the dynamics of both the trace distance and the quantum capacity, and show that the behavior of non-Markovianity based on both measures is qualitatively similar. Our results show that environments with a spectrum that contains a relevant low-frequency contribution are generally non-Markovian. We also find that the non-Markovianity of colored environments decreases when the number of fluctuators realizing the environment increases. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.5270v3.pdf"}
{"id": "1309.7144", "abstract": "  We present the results of a numerical adaptive mesh refinement hydrodynamical and N-body simulation in a Λ CDM cosmology. We focus on the analysis of the main properties of massive galaxies (M_* > 10^11 M_⊙) at z=0. For all the massive virtual galaxies we carry out a careful study of their one dimensional density, luminosity, velocity dispersion, and stellar population profiles. In order to best compare with observational data, the method to estimate the velocity dispersion is calibrated by using an approach similar to that performed in the observations, based on the stellar populations of the simulated galaxies. With these ingredients, we discuss the different properties of massive galaxies in our sample according to their morphological types, accretion histories and dynamical properties. We find that the galaxy merging history is the leading actor in shaping the massive galaxies that we see nowadays. Indeed, galaxies having experienced a turbulent life are the most massive in the sample and show the steepest metallicity gradients. Beside the importance of merging, only a small fraction of the final stellar mass has been formed ex-situ (10-50", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.7144v1.pdf"}
{"id": "1309.7345", "abstract": "  Symbiotic stars are long-orbital-period interacting-binaries characterized by extended emission over the whole electromagnetic range and by complex photometric and spectroscopic variability. In this paper, the first of a series, we present OGLE light curves of all the confirmed symbiotic stars in the Large Magellanic Cloud, with one exception. By careful visual inspection and combined time-series analysis techniques, we investigate for the first time in a systematic way the photometric properties of these astrophysical objects, trying in particular to distinguish the nature of the cool component (e.g., Semi-Regular Variable vs. OGLE Small-Amplitude Red Giant), to provide its first-order pulsational ephemerides, and to link all this information with the physical parameters of the binary system as a whole. Among the most interesting results, there is the discovery of a 20-year-long steady fading of Sanduleak's star, a peculiar symbiotic star known to produce the largest stellar jet ever discovered. We discuss by means of direct examples the crucial need for long-term multi-band observations to get a real understanding of symbiotic and other interacting binary stars. We eventually introduce BOMBOLO, a multi-band simultaneous imager for the SOAR 4m Telescope, whose design and construction we are currently leading. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.7345v1.pdf"}
{"id": "1310.0475", "abstract": "  We investigate the effect of helium abundance and α-element enhancement on the properties of convection in envelopes of solar-like main-sequence stars stars using a grid of 3D radiation hydrodynamic simulations. Helium abundance increases the mean molecular weight of the gas, and alters opacity by displacing hydrogen. Since the scale of the effect of helium may depend on the metallicity, the grid consists of simulations with three helium abundances (Y=0.1, 0.2, 0.3), each with two metallicities (Z=0.001, 0.020). We find that changing the helium mass fraction generally affects structure and convective dynamics in a way opposite to that of metallicity. Furthermore, the effect is considerably smaller than that of metallicity. The signature of helium differs from that of metallicity in the manner in which the photospheric velocity distribution is affected. We also find that helium abundance and surface gravity behave largely in similar ways, but differ in the way they affect the mean molecular weight. A simple model for spectral line formation suggests that the bisectors and absolute Doppler shifts of spectral lines depends on the helium abundance. We look at the effect of α-element enhancement and find that it has a considerably smaller effect on the convective dynamics in the SAL compared to that of helium abundance. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.0475v1.pdf"}
{"id": "1310.0623", "abstract": "  We studied the possibility of exciton condensation in a strongly correlated bilayer extended Hubbard model using Determinant Quantum Monte Carlo. To model both the onsite repulsion U and the interlayer interaction V we introduced a novel update scheme extending the standard Sherman-Morrison update. We observe that the sign problem increases dramatically with the inclusion of the interlayer interaction V, which prohibits at this stage a unequivocal conclusion regarding the presence of exciton condensation. However, enhancement of the interlayer tunneling results suggest that the strongest exciton condensation tendency lies around 10-20 ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.0623v1.pdf"}
{"id": "1310.1000", "abstract": "  The development of Chemical Vapour Deposition (CVD) diamond detectors requests for novel signal amplifiers, capable to match the superb signal-to-noise ratio and timing response of these detectors. Existing amplifiers are still far away from this goal and are the dominant contributors to the overall system noise and the main source of degradation of the energy and timing resolution. We tested a number of commercial amplifiers designed for diamond detector readout to identify the best solution for a particular application. This application required a deposited energy threshold below 100 keV and timing resolution of the order of 200 ps at 200 keV. None of tested amplifiers satisfies these requirements. The best solution to such application found to be the Cividec C6 amplifier, which allows 100 keV minimal threshold, but its coincidence timing resolution at 200 keV is as large as 1.2 ns. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.1000v1.pdf"}
{"id": "1310.1634", "abstract": "  We analyze cascades of defaults in an interbank loan market. The novel feature of this study is that the network structure and the size distribution of banks are derived from empirical data. We find that the ability of a defaulted institution to start a cascade depends on an interplay of shock size and connectivity. Further results indicate that the ability to limit default risk by spreading the lending to many counterparts decreased with the financial crisis. To evaluate the influence of the network structure on market stability, we compare the simulated cascades from the empirical network with results from different randomized network models. The results show that the empirical network has non-random features, which cannot be captured by rewired networks. The analysis also reveals that simulations assuming homogeneity for size of banks and loan contracts dramatically overestimates the fragility of the interbank market. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.1634v2.pdf"}
{"id": "1310.1767", "abstract": "  By adapting the iterative yardstick construction of Stockmeyer, we show that the reachability problem for vector addition systems with a stack does not have elementary complexity. As a corollary, the same lower bound holds for the satisfiability problem for a two-variable first-order logic on trees in which unbounded data may label only leaf nodes. Whether the two problems are decidable remains an open question. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.1767v1.pdf"}
{"id": "1310.5347", "abstract": "  The kernel least mean squares (KLMS) algorithm is a computationally efficient nonlinear adaptive filtering method that \"kernelizes\" the celebrated (linear) least mean squares algorithm. We demonstrate that the least mean squares algorithm is closely related to the Kalman filtering, and thus, the KLMS can be interpreted as an approximate Bayesian filtering method. This allows us to systematically develop extensions of the KLMS by modifying the underlying state-space and observation models. The resulting extensions introduce many desirable properties such as \"forgetting\", and the ability to learn from discrete data, while retaining the computational simplicity and time complexity of the original algorithm. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.5347v1.pdf"}
{"id": "1311.2483", "abstract": "  Global sensitivity analysis with variance-based measures suffers from several theoretical and practical limitations, since they focus only on the variance of the output and handle multivariate variables in a limited way. In this paper, we introduce a new class of sensitivity indices based on dependence measures which overcomes these insufficiencies. Our approach originates from the idea to compare the output distribution with its conditional counterpart when one of the input variables is fixed. We establish that this comparison yields previously proposed indices when it is performed with Csiszar f-divergences, as well as sensitivity indices which are well-known dependence measures between random variables. This leads us to investigate completely new sensitivity indices based on recent state-of-the-art dependence measures, such as distance correlation and the Hilbert-Schmidt independence criterion. We also emphasize the potential of feature selection techniques relying on such dependence measures as alternatives to screening in high dimension. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1311/1311.2483v1.pdf"}
{"id": "1311.2921", "abstract": "  Utilizing in-medium vector spectral functions which describe dilepton data in ultra-relativistic heavy-ion collisions, we conduct a comprehensive evaluation of QCD and Weinberg sum rules at finite temperature. The starting point is our recent study in vacuum, where the sum rules have been quantitatively satisfied using phenomenological axial-/vector spectral functions which describe hadronic tau-decay data. In the medium, the temperature dependence of condensates and chiral order parameters is taken from thermal lattice QCD where available, and otherwise estimated from a hadron resonance gas. Since little is known about the in-medium axial-vector spectral function, we model it with a Breit-Wigner ansatz allowing for smooth temperature variations of its width and mass parameters. Our study thus amounts to testing the compatibility of the ρ-broadening found in dilepton experiments with (the approach toward) chiral restoration, and thereby searching for viable in-medium axial-vector spectral functions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1311/1311.2921v2.pdf"}
{"id": "1311.7574", "abstract": "  The equilibrium statistical mechanics of one-dimensional lattice gases with interactions of arbitrary range and shape between first-neighbor atoms is solved exactly on the basis of statistically interacting vacancy particles. Two sets of vacancy particles are considered. In one set all vacancies are of one-cell size. In the other set the sizes of vacancy particles match the separation between atoms. Explicit expressions are obtained for the Gibbs free energy and the distribution of spaces between atoms at thermal equilibrium. Applications to various types of interaction potentials are discussed, including long-range potentials that give rise to phase transitions. Extensions to hard rod systems are straightforward and are shown to agree with existing results for lattice models and their continuum limits. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1311/1311.7574v2.pdf"}
{"id": "1312.4866", "abstract": "  Radical-ion pairs, fundamental for understanding photosynthesis and the avian magnetic compass, were recently shown to be biological open quantum systems. We here show that the coupling of the radical-pair's spin degrees of freedom to its decohering vibrational reservoir leads to a shift of the radical-pair's magnetic energy levels. The Lamb shift Hamiltonian is diagonal in the singlet-triplet basis, and results in a singlet-triplet energy splitting physically indistinguishable from an exchange interaction. This could have significant implications for understanding the energy level structure and the dynamics of photosynthetic reaction centers. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.4866v2.pdf"}
{"id": "1312.7281", "abstract": "  The connection of the binding energy and width of possible bound eta-mesic states is given to the complex scattering length for s-states in the hope that, with knowledge of the final state interaction this could be useful in searches of these states. In spite of the strong direct potential dependence of both observables this connection is seen to be very model independent even for various nuclei once the influence of also the effective range is considered. The importance of this term is pointed also for data analyses. Although the nucleus considered here is 12C, extension to other nuclei is implied in the background work. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.7281v1.pdf"}
{"id": "1312.7414", "abstract": "  We propose a technique to improve the search efficiency of the bag-of-words (BoW) method for image retrieval. We introduce a notion of difficulty for the image matching problems and propose methods that reduce the amount of computations required for the feature vector-quantization task in BoW by exploiting the fact that easier queries need less computational resources. Measuring the difficulty of a query and stopping the search accordingly is formulated as a stopping problem. We introduce stopping rules that terminate the image search depending on the difficulty of each query, thereby significantly reducing the computational cost. Our experimental results show the effectiveness of our approach when it is applied to appearance-based localization problem. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.7414v1.pdf"}
{"id": "1401.3391", "abstract": "  Since it is commonly believed that the observed large-scale structure of the Universe is an imprint of quantum fluctuations existing at the very early stage of its evolution, it is reasonable to pose the question: Do the effects of quantum nonlocality, which are well established now by the laboratory studies, manifest themselves also in the early Universe? We try to answer this question by utilizing the results of a few experiments, namely, with the superconducting multi-Josephson-junction loops and the ultracold gases in periodic potentials. Employing a close analogy between the above-mentioned setups and the simplest one-dimensional Friedmann-Robertson-Walker cosmological model, we show that the specific nonlocal correlations revealed in the laboratory studies might be of considerable importance also in treating the strongly-nonequilibrium phase transitions of Higgs fields in the early Universe. Particularly, they should substantially reduce the number of topological defects (e.g., domain walls) expected due to independent establishment of the new phases in the remote spatial regions. This gives us a hint for resolving a long-standing problem of the excessive concentration of topological defects, inconsistent with observational constraints. The same effect may be also relevant to the recent problem of the anomalous behavior of cosmic microwave background fluctuations at large angular scales. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.3391v2.pdf"}
{"id": "1401.3421", "abstract": "  Cryptographic algorithms are computationally costly and the challenge is more if we need to execute them in resource constrained embedded systems. Field Programmable Gate Arrays (FPGAs) having programmable logic de- vices and processing cores, have proven to be highly feasible implementation platforms for embedded systems providing lesser design time and reconfig- urability. Design parameters like throughput, resource utilization and power requirements are the key issues. The popular Elliptic Curve Cryptography (ECC), which is superior over other public-key crypto-systems like RSA in many ways, such as providing greater security for a smaller key size, is cho- sen in this work and the possibilities of its implementation in FPGA based embedded systems for both single and dual processor core architectures in- volving task parallelization have been explored. This exploration, which is first of its kind considering the other existing works, is a needed activity for evaluating the best possible architectural environment for ECC implementa- tion on FPGA (Virtex4 XC4VFX12, FF668, -10) based embedded platform. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.3421v1.pdf"}
{"id": "1401.4066", "abstract": "  We consider the problem of how to compute eigenvalues of a self-adjoint operator when a direct application of the Galerkin (finite-section) method is unreliable. The last two decades have seen the development of the so-called quadratic methods for addressing this problem. Recently a new perturbation approach has emerged, the idea being to perturb eigenvalues off the real line and, consequently, away from regions where the Galerkin method fails. We propose a simplified perturbation method which requires no á priori information and for which we provide a rigorous convergence analysis. The latter shows that, in general, our approach will significantly outperform the quadratic methods. We also present a new spectral enclosure for operators of the form A+iB where A is self-adjoint, B is self-adjoint and bounded. This enables us to control, very precisely, how eigenvalues are perturbed from the real line. The main results are demonstrated with examples including magnetohydrodynamics, Schrödinger and Dirac operators. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.4066v3.pdf"}
{"id": "1401.7461", "abstract": "  The role of disorder in the field of three-dimensional time reversal invariant topological insulators has become an active field of research recently. However, the computation of Z2 invariants for large, disordered systems still poses a considerable challenge. In this paper we apply and extend a recently proposed method based on the scattering matrix approach, which allows the study of large systems at reasonable computational effort with few-channel leads. By computing the Z2 invariant directly for the disordered topological Anderson insulator, we unambiguously identify the topological nature of this phase without resorting to its connection with the clean case. We are able to efficiently compute the Z2 phase diagram in the mass-disorder plane. The topological phase boundaries are found to be well described by the self consistent Born approximation, both for vanishing and finite chemical potential. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.7461v2.pdf"}
{"id": "1401.7700", "abstract": "  We consider the multi-unit random assignment problem in which agents express preferences over objects and objects are allocated to agents randomly based on the preferences. The most well-established preference relation to compare random allocations of objects is stochastic dominance (SD) which also leads to corresponding notions of envy-freeness, efficiency, and weak strategyproofness. We show that there exists no rule that is anonymous, neutral, efficient and weak strategyproof. For single-unit random assignment, we show that there exists no rule that is anonymous, neutral, efficient and weak group-strategyproof. We then study a generalization of the PS (probabilistic serial) rule called multi-unit-eating PS and prove that multi-unit-eating PS satisfies envy-freeness, weak strategyproofness, and unanimity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.7700v3.pdf"}
{"id": "1401.8030", "abstract": "  Transit fare arbitrage is the scenario when two or more commuters agree to swap tickets during travel in such a way that total cost is lower than otherwise. Such arbitrage allows pricing inefficiencies to be explored and exploited, leading to improved pricing models. In this paper we discuss the basics of fare arbitrage through an intuitive pricing framework involving population density. We then analyze the San Francisco Bay Area Rapid Transit (BART) system to understand underlying inefficiencies. We also provide source code and comprehensive list of pairs of trips with significant arbitrage gain at github.com/asifhaque/transit-arbitrage. Finally, we point towards a uniform payment interface for different kinds of transit systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.8030v1.pdf"}
{"id": "1402.0415", "abstract": "  We report a theoretical/computational approach for modeling the current-voltage characteristics of sensing proteins. The modeling is applied to a couple of transmembrane proteins, bacteriorhodopsin and proteorhodopsin, sensitive to visible light and promising biomaterials for the development of a new generation of photo-transducers. The agreement between theory and experiments sheds new light on the microscopic interpretation of charge transfer in proteins and biological materials in general. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.0415v1.pdf"}
{"id": "1402.0661", "abstract": "  The AllWISE processing pipeline has measured motions for all objects detected on WISE images taken between 2010 January and 2011 February. In this paper, we discuss new capabilities made to the software pipeline in order to make motion measurements possible, and we characterize the resulting data products for use by future researchers. Using a stringent set of selection criteria, we find 22,445 objects that have significant AllWISE motions, of which 3,525 have motions that can be independently confirmed from earlier 2MASS images yet lack any published motions in SIMBAD. Another 58 sources lack 2MASS counterparts and are presented as motion candidates only. Limited spectroscopic follow-up of this list has already revealed eight new L subdwarfs. These may provide the first hints of a \"subdwarf gap\" at mid-L types that would indicate the break between the stellar and substellar populations at low metallicities (i.e., old ages). Another object in the motion list – WISEA J154045.67-510139.3 – is a bright (J   9 mag) object of type M6; both the spectrophotometric distance and a crude preliminary parallax place it  6 pc from the Sun. We also compare our list of motion objects to the recently published list of 762 WISE motion objects from Luhman (2014). While these first large motion studies with WISE data have been very successful in revealing previously overlooked nearby dwarfs, both studies missed objects that the other found, demonstrating that many other nearby objects likely await discovery in the AllWISE data products. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.0661v1.pdf"}
{"id": "1403.1359", "abstract": "  We employ a variational method, in the framework of the Thomas-Fermi approximation, to study the effect of the symmetry energy on the neutron skin thickness and the symmetry energy coefficients of various neutron rich nuclei. We concentrate our interest on ^208Pb, ^124Sn, ^90Zr, and ^48Ca, although the method can be applied in the totality of medium and heavy neutron rich nuclei. Our approach has the advantage that the isospin asymmetry function α(r), which is the key quantity to calculate isovector properties of various nuclei, is directly related with the symmetry energy as a consequence of the variational principle. Moreover, the Coulomb interaction is included in a self-consistent way and its effects can be separated easily from the nucleon-nucleon interaction. We confirm, both qualitatively and quantitatively, the strong dependence of the symmetry energy on the various isovector properties for the relevant nuclei, using possible constraints between the slope and the value of the symmetry energy at the saturation density. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.1359v2.pdf"}
{"id": "1403.3272", "abstract": "  The behavior of a distributed charge in a Coulomb potential well is considered. It is shown that elements of a distributed charge can move along different trajectories, thus forming actually motion of a charge wave. Propagation over different trajectories is possible because elements of charge have on these trajectories the same energy. The overall velocity of motion of a charge wave is one half the velocity of individual elements in the wave, and the wave can move only along the φ axis of a spherical coordinate system. The following features in the motion of a distributed charge are stressed: each point of the charge is a center from which elements of the charge propagate with the same velocity within the solid angle 2π. The set of spherical functions needed to describe a distributed charge is specified, and it is shown that a charge cannot have spherical symmetry. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.3272v1.pdf"}
{"id": "1403.5563", "abstract": "  We investigate whether the satellite luminosity function (LF) of primary galaxies identified in the Sloan Digital Sky Survey (SDSS) depends on whether the host galaxy is in a filament or not. Isolated primary galaxies are identified in the SDSS spectroscopic sample while potential satellites (that are up to 4 magnitudes fainter than their hosts) are searched for in the much deeper photometric sample. Filaments are constructed from the galaxy distribution by the \"Bisous\" process. Isolated primary galaxies are divided into two subsamples: those in filaments and those not in filaments. We examine the stacked mean satellite LF of both the filament and non-filament sample and find that, on average, the satellite LFs of galaxies in filaments is significantly higher than those of galaxies not in filaments. The filamentary environment can increases the abundance of the brightest satellites (M_sat. < M_prim. + 2.0), by a factor of ∼ 2 compared with non-filament isolated galaxies. This result is independent of primary galaxy magnitude although the satellite LF of galaxies in the faintest magnitude bin, is too noisy to determine if such a dependence exists. Since our filaments are extracted from a spectroscopic flux-limited sample, we consider the possibility that the difference in satellite LF is due to a redshift, colour or environmental bias, finding these to be insufficient to explain our result. The dependence of the satellite LF on the cosmic web suggests that the filamentary environment may have a strong effect on the efficiency of galaxy formation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.5563v3.pdf"}
{"id": "1403.5884", "abstract": "  The entropy of network ensembles characterizes the amount of information encoded in the network structure, and can be used to quantify network complexity, and the relevance of given structural properties observed in real network datasets with respect to a random hypothesis. In many real networks the degrees of individual nodes are not fixed but change in time, while their statistical properties, such as the degree distribution, are preserved. Here we characterize the distribution of entropy of random networks with given degree sequences, where each degree sequence is drawn randomly from a given degree distribution. We show that the leading term of the entropy of scale-free network ensembles depends only on the network size and average degree, and that entropy is self-averaging, meaning that its relative variance vanishes in the thermodynamic limit. We also characterize large fluctuations of entropy that are fully determined by the average degree in the network. Finally, above a certain threshold, large fluctuations of the average degree in the ensemble can lead to condensation, meaning that a single node in a network of size N can attract O(N) links. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.5884v3.pdf"}
{"id": "1404.2517", "abstract": "  We calculate the in-medium masses of the bottomonium states (Υ(1S), Υ(2S), Υ(3S) and Υ(4S)) in isospin asymmetric strange hadronic matter at finite temperatures. The medium modifications of the masses arise due to the interaction of these heavy quarkonium states with the gluon condensates of QCD. The gluon condensates in the hot hadronic matter are computed from the medium modification of a scalar dilaton field within a chiral SU(3) model, introduced in the hadronic model to incorporate the broken scale invariance of QCD. There is seen to be drop in the masses of the bottomonium states and mass shifts are observed to be quite considerable at high densities for the excited states. The effects of density, isospin asymmetry, strangeness as well as temperature of the medium on the masses of the Υ-states are investigated. The effects of the isospin asymmetry as well as strangeness fraction of the medium are seen to be appreciable at high densities and small temperatures. The density effects are the most dominant medium effects which should have observable consequences in the compressed baryonic matter (CBM) in the heavy ion collision experiments in the future facility at FAIR, GSI. The study of the Υ states will however require access to energies higher than the energy regime planned at CBM experiment. The density effects on the bottomonium masses should also show up in the dilepton spectra at the SPS energies, especially for the excited states for which the mass drop is observed to quite appreciable. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.2517v2.pdf"}
{"id": "1404.3938", "abstract": "  The structure of the photospheric magnetic field during solar flares is examined using echelle spectropolarimetric observations. The study is based on several Fe I and Cr I lines observed at locations corresponding to brightest Hα emission during thermal phase of flares. The analysis is performed by comparing magnetic field values deduced from lines with different magnetic sensitivities, as well as by examining the fine structure of I± V Stokes profiles splitting. It is shown that the field has at least two components, with stronger unresolved flux tubes embedded in weaker ambient field. Based on a two-component magnetic field model, we compare observed and synthetic line profiles and show that the field strength in small-scale flux tubes is about 2-3 kG. Furthermore, we find that the small-scale flux tubes are associated with flare emission, which may have implications for flare phenomenology. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.3938v1.pdf"}
{"id": "1404.4879", "abstract": "  We present multi-wavelength observations that trace more than 40 years in the life of the active galactic nucleus (AGN) in Mrk 590, traditionally known as a classic Seyfert 1 galaxy. From spectra recently obtained from HST, Chandra, and the Large Binocular Telescope, we find that the activity in the nucleus of Mrk 590 has diminished so significantly that the continuum luminosity is a factor of 100 lower than the peak luminosity probed by our long baseline observations. Furthermore, the broad emission lines, once prominent in the UV/optical spectrum, have all but disappeared. Since AGN type is defined by the presence of broad emission lines in the optical spectrum, our observations demonstrate that Mrk 590 has now become a \"changing look\" AGN. If classified by recent optical spectra, Mrk 590 would be a Seyfert  1.9-2, where the only broad emission line still visible in the optical spectrum is a weak component of Halpha. As an additional consequence of this change, we have definitively detected UV narrow-line components in a Type 1 AGN, allowing an analysis of these emission-line components with high-resolution COS spectra. These observations challenge the historical paradigm that AGN type is only a consequence of the line of sight viewing angle toward the nucleus in the presence of a geometrically-flattened, obscuring medium (i.e., the torus). Our data instead suggest that the current state of Mrk 590 is a consequence of the change in luminosity, which implies the black hole accretion rate has significantly decreased. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.4879v2.pdf"}
{"id": "1405.6576", "abstract": "  In this work we provide a numerical method to obtain the Bloch-Nordsieck spectral function at finite temperature in the framework of the 2PI approximation. We find that the 2PI results nicely agree with the exact one, provided we perform a coupling constant matching. In the paper we present the resulting finite temperature running of the 2PI coupling constant. This result may apply for the finite temperature behavior of the coupling constant in QED, too. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.6576v1.pdf"}
{"id": "1405.7666", "abstract": "  We discuss a few mathematical aspects of random dynamical decoupling, a key tool procedure in quantum information theory. In particular, we place it in the context of discrete stochastic processes, limit theorems and CPT semigroups on matrix algebras. We obtain precise analytical expressions for expectation and variance of the density matrix and fidelity over time in the continuum-time limit depending on the system Lindbladian, which then lead to rough short-time estimates depending only on certain coupling strengths. We prove that dynamical decoupling does not work in the case of intrinsic (i.e., not environment-induced) decoherence, and together with the above-mentioned estimates this yields a novel method of partially identifying intrinsic decoherence. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.7666v3.pdf"}
{"id": "1406.1919", "abstract": "  We study the finite temperature Hartree-Fock-BCS approximation for selected stable Sn nuclei with zero-range Skyrme forces. Hartree Fock BCS approximation allows for a straightforward interpretation of the results since it involves u and v's which are not matrices as in HFB. Pairing transitions from superfluid to the normal state are studied with respect to the temperature. The temperature dependence of the nuclear radii and neutron skin are also analyzed. An increase of proton and neutron radii is obtained in neutron rich nuclei especially above the critical temperature. Using different Skyrme energy functionals, it is found that the correlation between the effective mass in symmetric nuclear matter and the critical temperature depends on the pairing prescription. The temperature dependence of the nucleon effective mass is also investigated, showing that proton and neutron effective masses display different behavior below and above the critical temperature, due to the small temperature dependence of the density. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.1919v2.pdf"}
{"id": "1406.6804", "abstract": "  In the sense of Palamodov, a preabelian category is semi-abelian if for every morphism the natural morphism between the cokernel of its kernel and the kernel of its cokernel is simultaneously a monomorphism and an epimorphism. In this article we present several conditions which are all equivalent to semi-abelianity. First we consider left and right semi-abelian categories in the sense of Rump and establish characterizations of these notions via six equivalent properties. Then we use these properties to deduce the characterization of semi-abelianity. Finally, we investigate two examples arising in functional analysis which illustrate that the notions of right and left semi-abelian categories are distinct and in particular that such categories occur in nature. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.6804v1.pdf"}
{"id": "1406.7084", "abstract": "  Time-integrated quantities such as work and heat increase incessantly in time during nonequilibrium processes near steady states. In the long-time limit, the average values of work and heat become asymptotically equivalent to each other, since they only differ by a finite energy change in average. However, the fluctuation theorem (FT) for the heat is found not to hold with the equilibrium initial ensemble, while the FT for the work holds. This reveals an intriguing effect of everlasting initial memory stored in rare events. We revisit the problem of a Brownian particle in a harmonic potential dragged with a constant velocity, which is in contact with a thermal reservoir. The heat and work fluctuations are investigated with initial Boltzmann ensembles at temperatures generally different from the reservoir temperature. We find that, in the infinite-time limit, the FT for the work is fully recovered for arbitrary initial temperatures, while the heat fluctuations significantly deviate from the FT characteristics except for the infinite initial-temperature limit (a uniform initial ensemble). Furthermore, we succeed in calculating finite-time corrections to the heat and work distributions analytically, using the modified saddle point integral method recently developed by us. Interestingly, we find non-commutativity between the infinite-time limit and the infinite-initial-temperature limit for the probability distribution function (PDF) of the heat. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.7084v1.pdf"}
{"id": "1407.1879", "abstract": "  The stability conditions of a renormalization group improved effective potential have been discussed in the case of scalar QED and QCD with a colorless scalar. We calculate the same potential in these models assuming the existence of non-perturbative fixed points associated to a conformal phase. In the case of scalar QED the barrier of instability found previously is barely displaced as we approach the fixed point, and in the case of QCD with a colorless scalar not only the barrier is changed but the local minimum of the potential is also changed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.1879v2.pdf"}
{"id": "1407.4459", "abstract": "  In this paper, we address the question: What is the probability of stellar-mass black hole (BH) binaries co-existing in a globular cluster with an intermediate-mass black hole (IMBH)? Our results suggest that the detection of one or more BH binaries can strongly constrain the presence of an IMBH in most Galactic globular clusters. More specifically, the detection of one or more BH binaries could strongly indicate against the presence of an IMBH more massive than ≳ 10^3 M_⊙ in roughly 80% of the clusters in our sample. To illustrate this, we use a combination of N-body simulations and analytic methods to weigh the rate of formation of BH binaries against their ejection and/or disruption rate via strong gravitational interactions with the central (most) massive BH.   The eventual fate of a sub-population of stellar-mass BHs (with or without binary companions) is for all BHs to be ejected from the cluster by the central IMBH, leaving only the most massive stellar-mass BH behind to form a close binary with the IMBH. During each phase of evolution, we discuss the rate of inspiral of the central BH-BH pair as a function of both the properties of the binary and its host cluster. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.4459v1.pdf"}
{"id": "1407.5342", "abstract": "  We update the phenomenology of gauge singlet extensions of the Standard Model scalar sector and their implications for the electroweak phase transition. Considering the introduction of one real scalar singlet to the scalar potential, we analyze present constraints on the potential parameters from Higgs coupling measurements at the Large Hadron Collider (LHC) and electroweak precision observables for the kinematic regime in which no new scalar decay modes arise. We then show how future precision measurements of Higgs boson signal strengths and Higgs self-coupling could probe the scalar potential parameter space associated with a strong first-order electroweak phase transition. We illustrate using benchmark precision for several future collider options, including the High Luminosity LHC (HL-LHC), the International Linear Collider (ILC), TLEP, China Electron Positron Collider (CEPC), and a 100 TeV proton-proton collider, such as the Very High Energy LHC (VHE-LHC) or the Super proton-proton Collider (SPPC). For the regions of parameter space leading to a strong first order electroweak phase transition, we find that there exists considerable potential for observable deviations from purely Standard Model Higgs properties at these prospective future colliders. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.5342v2.pdf"}
{"id": "1407.7181", "abstract": "  A new and simple technique has been developed using plastic scintillator detectors for gamma ray and cosmic ray spectroscopy without single channel analyzer (SCA) or multichannel analyzer (MCA). In these experiments only a leading edge discriminator (LED) and NIM scalers have been used. Energy calibration of gamma spectra in plastic scintillators has been done using Co^60 and Cs^137 sources. The details experimental technique, analysis procedure and experimental results has been presented in this article. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.7181v4.pdf"}
{"id": "1407.7864", "abstract": "  We show that the coolest known object that is probably formed in a star-like mode is a free-floating planet. We discovered recently that the free-floating planetary mass object OTS,44 (M9.5,  12 Jupiter masses, age  2 Myr) has significant accretion and a substantial disk. This demonstrates that the processes that characterize the canonical star-like mode of formation apply to isolated objects down to a few Jupiter masses. We detected in VLT/SINFONI spectra that OTS44 has strong, broad, and variable Paschen beta emission. This is the first evidence for active accretion of a free-floating planet. The object allows us to study accretion and disk physics at the extreme and can be seen as free-floating analog of accreting planets that orbit stars. Our analysis of OTS44 shows that the mass-accretion rate decreases continuously from stars of several solar masses down to free-floating planets. We determined, furthermore, the disk mass (10 Earth masses) and further disk properties of OTS44 through modeling its SED including Herschel far-IR data. We find that objects between 14 and 0.01 solar masses have the same ratio of the disk-to-central-mass of about 1", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.7864v1.pdf"}
{"id": "1407.7957", "abstract": "  Through the Monte Carlo simulation of the three-dimensional, three-state Potts model, which is a paradigm of finite-temperature pure gauge QCD, we study the fluctuations of generalized susceptibilities near the temperatures of external fields of first-, second-order phase transitions and crossover. Similar peak-like fluctuation appears in the second order susceptibility at three given external fields. Oscillation-like fluctuation appears in the third and fourth order susceptibilities. We find that these non-monotonic fluctuations are not only associated with the second-order phase transition, but also the first-order one and crossover in a system of finite-size. We further present the finite-size scaling analysis of the second and fourth order susceptibilities, respectively. The exponent of the scaling characterizes the order of the transitions, or the crossover. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.7957v1.pdf"}
{"id": "1408.0421", "abstract": "  This work considers the behavior of the height distributions of the equipotential lines in a region confined by two interfaces: a cathode with an irregular interface and a distant flat anode. Both boundaries, which are maintained at distinct and constant potential values, are assumed to be conductors. The morphology of the cathode interface results from the deposit of 2 × 10^4 monolayers that are produced using a single competitive growth model based on the rules of the Restricted Solid on Solid and Ballistic Deposition models, both of which belong to the Kadar-Parisi-Zhang (KPZ) universality class. At each time step, these rules are selected with probability p and q = 1 - p. For several irregular profiles that depend on p, a family of equipotential lines is evaluated. The lines are characterized by the skewness and kurtosis of the height distribution. The results indicate that the skewness of the equipotential line increases when they approach the flat anode, and this increase has a non-trivial convergence to a delta distribution that characterizes the equipotential line in a uniform electric field. The morphology of the equipotential lines is discussed; the discussion emphasizes their features for different ranges of p that correspond to positive, null and negative values of the coefficient of the non-linear term in the KPZ equation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.0421v1.pdf"}
{"id": "1408.0863", "abstract": "  We provide accurate projected augmented wave (PAW) datasets for rare-earth (RE) elements with some suggested Hubbard U values allowing efficient plane-wave calculations. Solid state tests of generated datasets were performed on rare-earth nitrides. Through density of state (DOS) and equation of state (EoS) comparisons, generated datasets were shown to yield excellent results comparable to highly accurate all-electron full-potential linearized augmented plane-wave plus local orbital (FLAPW+LO) calculations. Hubbard U values for trivalent RE ions are determined according to hybrid functional calculations. We believe that these new and open-source PAW datasets will allow further studies on rare-earth materials. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.0863v1.pdf"}
{"id": "1408.3484", "abstract": "  The ALICE experiment at the Large Hadron Collider (LHC) proposes major detector upgrades to fully exploit the increase of the luminosity of the LHC in RUN 3 and to extend the physics reach for rare probes at low transverse momentum. The Time Projection Chamber (TPC) is one of the main tracking and PID devices in the central barrel of ALICE. The maximum trigger rate of the TPC is currently limited to about 3.5 kHz by the operation of a gating grid system. In order to make full use of the luminosity in RUN 3, the TPC is foreseen to be operated in an ungated mode with continuous readout. The existing MWPC readout will be replaced by a Micro-Pattern Gaseous Detector (MPGD) based readout, which provides intrinsic ion capture capability without gating. Extensive detector R&D employing Gas Electron Multiplier (GEM) and Micro-Mesh Gaseous detector (Micromegas) technologies, and simulation studies to advance the techniques for the corrections of space-charge distortions have been performed since 2012. In this paper, the expected detector performance and the status of the R&D program to achieve this ambitious goal are described. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.3484v1.pdf"}
{"id": "1408.3540", "abstract": "  The electronic structure and numerous magnetic properties of MnBi magnetic systems are investigated using local spin density approximation (LSDA) with on-cite Coulomb correlations (LSDA+U) included. We show that the inclusion of Coulomb correlations provides a much better description of equilibrium magnetic moments on Mn atom as well as the magnetic anisotropy energy (MAE) behavior with temperature and magneto-optical effects. We found that the inversion of the anisotropic pairwise exchange interaction between Bi atoms is responsible for the observed spin reorientation transition at 90 K. This interaction appears as a result of strong spin orbit coupling on Bi atoms, large magnetic moments on Mn atoms, significant p-d hybridization between Mn and Bi atoms, and it depends strongly on lattice constants. A better agreement with the magneto-optical Kerr measurements at higher energies is obtained. We also present the detailed investigation of the Fermi surface, the de Haas-van Alphen (dHvA) effect and the X-ray magnetic circular dichroism in MnBi. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.3540v2.pdf"}
{"id": "1408.6388", "abstract": "  In the Red-Blue Dominating Set problem, we are given a bipartite graph G = (V_B ∪ V_R,E) and an integer k, and asked whether G has a subset D ⊆ V_B of at most k \"blue\" vertices such that each \"red\" vertex from V_R is adjacent to a vertex in D. We provide the first explicit linear kernel for this problem on planar graphs, of size at most 43k. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.6388v3.pdf"}
{"id": "1409.3697", "abstract": "  Current and upcoming surveys will measure the cosmological parameters with an extremely high accuracy. The primary goal of these observations is to eliminate some of the currently viable cosmological models created to explain the late time accelerated expansion (either real or only inferred). However, most of the statistical tests used in cosmology have a strong requirement: the use of a model to fit the data. Recently there has been an increased interest on finding tests that are model independent, i.e. to have a function that depends entirely on observed quantities and not on the model, see for instance [1]. In this letter we present an alternative consistency check at the perturbative level for a homogeneous and isotropic Universe filled with a dark energy component. This test makes use of the growth of matter perturbations data and it is able to not only test the homogeneous and isotropic Universe but also, within the framework of a Friedmann-Lemaître-Robertson-Walker Universe, if the dark energy component is able to cluster, if there is a tension in the data or if we are dealing with a modification of gravity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1409/1409.3697v1.pdf"}
{"id": "1410.1868", "abstract": "  We study the effects of strong electron-electron interactions on the surface of cubic topological Kondo insulators (such as samarium hexaboride, SmB_6). Cubic topological Kondo insulators generally support three copies of massless Dirac nodes on the surface, but only two of them are energetically degenerate and exhibit an energy offset relative to the third one. With a tunable chemical potential, when the surface states host electron and hole pockets of comparable size, strong interactions may drive this system into rotational symmetry breaking nematic and translational symmetric breaking excitonic spin- or charge-density-wave phases, depending on the relative chirality of the Dirac cones. Taking a realistic surface band structure into account we analyze the associated Ginzburg-Landau theory and compute the mean field phase diagram for interacting surface states. Beyond mean field theory, this system can be described by a two-component isotropic Ashkin-Teller model at finite temperature, and we outline the phase diagram of this model. Our theory provides a possible explanation of recent measurements which detect a two-fold symmetric magnetoresistance and an upturn in surface resistivity with tunable gate voltage in SmB_6. Our discussion can also be germane to other cubic topological insulators, such as ytterbium hexaboride (YbB_6), plutonium hexaboride (PuB_6). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.1868v2.pdf"}
{"id": "1410.2454", "abstract": "  By studying the individual star-formation histories of the bulges and discs of lenticular (S0) galaxies, it is possible to build up a sequence of events that leads to the cessation of star formation and the consequent transformation from the progenitor spiral. In order to separate the bulge and disc stellar populations, we spectroscopically decomposed long-slit spectra of Virgo Cluster S0s into bulge and disc components. Analysis of the decomposed spectra shows that the most recent star formation activity in these galaxies occurred within the bulge regions, having been fuelled by residual gas from the disc. These results point towards a scenario where the star formation in the discs of spiral galaxies are quenched, followed by a final episode of star formation in the central regions from the gas that has been funnelled inwards through the disc. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.2454v1.pdf"}
{"id": "1410.2620", "abstract": "  With the rapid growth of smartphone and tablet users, Device-to-Device (D2D) communications have become an attractive solution for enhancing the performance of traditional cellular networks. However, relevant security issues involved in D2D communications have not been addressed yet. In this paper, we investigate the security requirements and challenges for D2D communications, and present a secure and efficient key agreement protocol, which enables two mobile devices to establish a shared secret key for D2D communications without prior knowledge. Our approach is based on the Diffie-Hellman key agreement protocol and commitment schemes. Compared to previous work, our proposed protocol introduces less communication and computation overhead. We present the design details and security analysis of the proposed protocol. We also integrate our proposed protocol into the existing Wi-Fi Direct protocol, and implement it using Android smartphones. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.2620v1.pdf"}
{"id": "1410.5345", "abstract": "  We discuss an efficient numerical scheme for the recursive filtering of diffusive quantum stochastic master equations. We show that the resultant quantum trajectory is robust and may be used for feedback based on inefficient measurements. The proposed numerical scheme is amenable to approximation, which can be used to further reduce the computational burden associated with calculating quantum trajectories and may allow real-time quantum filtering. We provide a two-qubit example where feedback control of entanglement may be within the scope of current experimental systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.5345v2.pdf"}
{"id": "1410.5418", "abstract": "  This paper presents a relativistic symmetrical interpretation of the Dirac equation in 1+1 dimensions which predicts no zitterbewegung for a free spin-1/2 particle. This could resolve the longstanding puzzle of zitterbewegung in relativistic quantum mechanics, and help clarify the physical meaning of the zitterbewegung currently under investigation in many-particle systems. Together with an earlier paper describing a relativistic symmetrical interpretation of the Klein-Gordon equation <cit.>, this new interpretation resolves some inconsistencies in the conventional interpretations of both equations. This new interpretation also makes several experimental predictions that differ from the conventional interpretation of the Dirac equation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.5418v1.pdf"}
{"id": "1410.7656", "abstract": "  It is shown that the causal structure associated to string-like solutions of the Fadeev-Niemi (FN) model is described by an effective metric. Remarkably, the surfaces characterising the causal replacement depend on the energy momentum tensor of the background soliton and carry implicitly a topological invariant π_3(𝕊^2). As a consequence, it follows that the pre- image curves in ℝ^3 nontrivialy define directions where the cones remain unchanged. It turns out that these results may be of importance in understanding time dependent solutions (collisions/scatterings) numerically or analytically. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.7656v1.pdf"}
{"id": "1410.8067", "abstract": "  The question of what is genuinely quantum about weak values is only ever going to elicit strongly subjective opinions—it is not a scientific question. Good questions, when comparing theories, are operational—they deal with the unquestionable outcomes of experiment. We give the anomalous shift of weak values an objective meaning through a generalization to an operational definition of anomalous post-selected averages. We show the presence of these averages necessitate correlations in every model giving rise to them—quantum or classical. Characterizing such correlations shows that they are ubiquitous. We present the simplest classical example without the need of disturbance realizing these generalized anomalous weak values. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.8067v1.pdf"}
{"id": "1410.8343", "abstract": "  By using the constrained-phase quantum Monte Carlo method, we performed a systematic study of the pairing correlations in the ground state of the doped Kane-Mele-Hubbard model on a honeycomb lattice. We find that pairing correlations with d+id symmetry dominate close to half filling, but pairing correlations with p+ip symmetry dominate as hole doping moves the system below three-quarters filling. We correlate these behaviors of the pairing correlations with the topology of the Fermi surfaces of the non-interacting problem. We also find that the effective pairing correlation is enhanced greatly as the interaction increases, and these superconducting correlations are robust against varying the spin-orbit coupling strength. Our numerical results suggest a possible way to realize spin triplet superconductivity in doped honeycomb-like materials or ultracold atoms in optical traps. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.8343v2.pdf"}
{"id": "1411.0188", "abstract": "  We study the formation and dynamics of shock waves initiated by a repulsive potential in a superfluid unitary Fermi gas by using the order-parameter equation. In the theoretical framework, the regularization process of shock waves mediated by the quantum pressure term is purely dispersive. Our results show good agreement with the experiment of Joseph et al. [Phys. Rev. Lett. 106, 150401 (2011)]. We reveal that the boxlike-shaped density peak observed in the experiment consists of many vortex rings due to the transverse instability of the dispersive shock wave. In addition, we study the transition from a sound wave to subsonic shock waves by increasing the strength of the repulsive potential and show a strong qualitative change in the propagation speed of the wavefronts. In the relatively small strength regime, the speed decreases below the sound speed with increasing the strength as a scaling behavior, while in the large regime the speed remains almost unchanged, which is found to be the same expansion speed of the proliferation of the vortex rings. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1411/1411.0188v2.pdf"}
{"id": "1411.0525", "abstract": "  The influence of a distributed Bragg reflector composed of ZnTe, MgTe, and MgSe superlattices on photoluminescence of self assembled CdTe quantum dots (QD) emitting in the yellow spectral range is investigated. In the case of QDs grown on a distributed Bragg reflector the photoluminescence intensity is enhanced by more than one order of magnitude, whereas the single QD lines are broadened as compared to the case of QDs grown on a ZnTe buffer. Structural and chemical analysis reveal an unintentional formation of a thin ZnSe layer induced by the growth interruption needed for the deposition of the QDs sheet. Sharp emission lines from individual quantum dots are recovered in the case of a thicker ZnTe layer grown prior to the QDs. This indicates that growth interruptions might be responsible for the QD emission line broadening. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1411/1411.0525v1.pdf"}
{"id": "1412.1373", "abstract": "  Standard geostatistical models assume second order stationarity of the underlying Random Function. In some instances, there is little reason to expect the spatial dependence structure to be stationary over the whole region of interest. In this paper, we introduce a new model for second order non-stationary Random Functions as a convolution of an orthogonal random measure with a spatially varying random weighting function. This new model is a generalization of the common convolution model where a non-random weighting function is used. The resulting class of non-stationary covariance functions is very general, flexible and allows to retrieve classes of closed-form non-stationary covariance functions known from the literature, for a suitable choices of the random weighting functions family. Under the framework of a single realization and local stationarity, we develop parameter inference procedure of these explicit classes of non-stationary covariance functions. From a local variogram non-parametric kernel estimator, a weighted local least-squares approach in combination with kernel smoothing method is developed to estimate the parameters. Performances are assessed on two real datasets: soil and rainfall data. It is shown in particular that the proposed approach outperforms the stationary one, according to several criteria. Beyond the spatial predictions, we also show how conditional simulations can be carried out in this non-stationary framework. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.1373v1.pdf"}
{"id": "1412.1377", "abstract": "  The Continuous Electron Beam Accelerator Facility (CEBAF) and associated experimental equipment at Jefferson Lab comprise a unique facility for experimental nuclear physics. This facility is presently being upgraded, which will enable a new experimental program with substantial discovery potential to address important topics in nuclear, hadronic, and electroweak physics. Further in the future, it is envisioned that the Laboratory will evolve into an electron-ion colliding beam facility. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.1377v1.pdf"}
{"id": "1412.2356", "abstract": "  This paper presents a method for path-following for quadcopter trajectories in real time. Non-Linear Guidance Logic is used to find the intercepts of the subsequent destination. Trajectory tracking is implemented by formulating the trajectory of the quadcopter using its jerk, in discrete time, and then solving a convex optimization problem on each decoupled axis. Based on the maximum possible thrust and angular rates of the quadcopter, feasibility constraints for the quadcopter have been derived. In this report we describe the design and implementation of explicit MPC controllers where the controllers were executed on a computer using sparse solvers to control the vehicle in hovering flight. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.2356v1.pdf"}
{"id": "1412.7624", "abstract": "  In fading channels, power allocation over channel state may bring a rate increment compared to the fixed constant power mode. Such a rate increment is referred to power allocation gain. It is expected that the power allocation gain varies for different relay protocols. In this paper, Decode-and-Forward (DF) and Compress-and-Forward (CF) protocols are considered. We first establish a general framework for relay power allocation of DF and CF over channel state in half-duplex relay channels and present the optimal solution for relay power allocation with auxiliary parameters, respectively. Then, we reconsider the power allocation problem for one hybrid scheme which always selects the better one between DF and CF and obtain a near optimal solution for the hybrid scheme by introducing an auxiliary rate function as well as avoiding the non-concave rate optimization problem. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.7624v1.pdf"}
{"id": "1501.00344", "abstract": "  We introduce a tight-binding chain with a single impurity to act as a quantum data bus for perfect quantum state transfer. Our proposal is based on the weak coupling limit of the two outermost quantum dots to the data bus. First show that the data bus has an energy gap between the ground and first-excited states in the single-particle case induced by the impurity in the single particle case. By connecting two quantum dots to two sites of the data bus, the system can accomplish a high-fidelity and long-distance quantum state transfer. Numerical simulations were performed for a finite system; the results show that the numerical and analytical results of the effective coupling strength agree well with each other. Moreover, we study the robustness of this quantum communication protocol in the presence of disorder in the couplings between the nearest-neighbor quantum dots. We find that the gap of the system plays an important role in robust quantum state transfer. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.00344v1.pdf"}
{"id": "1501.05163", "abstract": "  Gyrokinetic validation studies are crucial in developing confidence in the model incorporated in numerical simulations and thus improving their predictive capabilities. As one step in this direction, we simulate an ASDEX Upgrade discharge with the GENE code, and analyze various fluctuating quantities and compare them to experimental measurements. The approach taken is the following. First, linear simulations are performed in order to determine the turbulence regime. Second, the heat fluxes in nonlinear simulations are matched to experimental fluxes by varying the logarithmic ion temperature gradient within the expected experimental error bars. Finally, the dependence of various quantities with respect to the ion temperature gradient is analyzed in detail. It is found that density and temperature fluctuations can vary significantly with small changes in this parameter, thus making comparisons with experiments very sensitive to uncertainties in the experimental profiles. However, cross-phases are more robust, indicating that they are better observables for comparisons between gyrokinetic simulations and experimental measurements. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.05163v1.pdf"}
{"id": "1501.06066", "abstract": "  Distance weighted discrimination (DWD) was originally proposed to handle the data piling issue in the support vector machine. In this paper, we consider the sparse penalized DWD for high-dimensional classification. The state-of-the-art algorithm for solving the standard DWD is based on second-order cone programming, however such an algorithm does not work well for the sparse penalized DWD with high-dimensional data. In order to overcome the challenging computation difficulty, we develop a very efficient algorithm to compute the solution path of the sparse DWD at a given fine grid of regularization parameters. We implement the algorithm in a publicly available R package sdwd. We conduct extensive numerical experiments to demonstrate the computational efficiency and classification performance of our method. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.06066v1.pdf"}
{"id": "1501.06390", "abstract": "  We report on the successful demonstration of selective acceleration of deuterium ions by target-normal sheath acceleration (TNSA) with a high-energy petawatt laser. TNSA typically produces a multi-species ion beam that originates from the intrinsic hydrocarbon and water vapor contaminants on the target surface. Using the method first developed by Morrison, et al.,^1 an ion beam with >99% deuterium ions and peak energy 14 MeV/nucleon is produced with a 200 J, 700 fs, >10^20 W/cm^2 laser pulse by cryogenically freezing heavy water (D_2O) vapor onto the rear surface of the target prior to the shot. Within the range of our detectors (0-8.5^∘), we find laser-to-deuterium-ion energy conversion efficiency of 4.3% above 0.7 MeV/nucleon while a conservative estimate of the total beam gives a conversion efficiency of 9.4%. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.06390v2.pdf"}
{"id": "1502.01188", "abstract": "  The introduction of smart electricity meters with cellular radio interface puts an additional load on the wireless cellular networks. Currently, these meters are designed for low duty cycle billing and occasional system check, which generates a low-rate sporadic traffic. As the number of distributed energy resources increases, the household power will become more variable and thus unpredictable from the viewpoint of the Distribution System Operator (DSO). It is therefore expected, in the near future, to have an increased number of Wide Area Measurement System (WAMS) devices with Phasor Measurement Unit (PMU)-like capabilities in the distribution grid, thus allowing the utilities to monitor the low voltage grid quality while providing information required for tighter grid control. From a communication standpoint, the traffic profile will change drastically towards higher data volumes and higher rates per device. In this paper, we characterize the current traffic generated by smart electricity meters and supplement it with the potential traffic requirements brought by introducing enhanced Smart Meters, i.e., meters with PMU-like capabilities. Our study shows how GSM/GPRS and LTE cellular system performance behaves with the current and next generation smart meters traffic, where it is clearly seen that the PMU data will seriously challenge these wireless systems. We conclude by highlighting the possible solutions for upgrading the cellular standards, in order to cope with the upcoming smart metering traffic. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.01188v4.pdf"}
{"id": "1502.01943", "abstract": "  Gaussian Mixture Models (GMM) have found many applications in density estimation and data clustering. However, the model does not adapt well to curved and strongly nonlinear data. Recently there appeared an improvement called AcaGMM (Active curve axis Gaussian Mixture Model), which fits Gaussians along curves using an EM-like (Expectation Maximization) approach.   Using the ideas standing behind AcaGMM, we build an alternative active function model of clustering, which has some advantages over AcaGMM. In particular it is naturally defined in arbitrary dimensions and enables an easy adaptation to clustering of complicated datasets along the predefined family of functions. Moreover, it does not need external methods to determine the number of clusters as it automatically reduces the number of groups on-line. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.01943v1.pdf"}
{"id": "1502.02548", "abstract": "  The search for topological superconductors which support Majorana fermion excitations has been an important topic in condensed matter physics. In this work, we propose a new experimental scheme for engineering topological superconductors. In this scheme, by manipulating the superlattice structure of organic molecules placed on top of a superconductor with Rashba spin-orbit coupling, topological superconducting phases can be achieved without fine-tuning the chemical potential. Moreover, superconductors with different Chern numbers can be obtained by changing the superlattice structure of the organic molecules. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.02548v1.pdf"}
{"id": "1502.05157", "abstract": "  The unusually large NOAA active region 2192, observed in October 2014, was outstanding in its productivity of major two-ribbon flares without coronal mass ejections. On a large scale, a predominantly north-south oriented magnetic system of arcade fields served as a strong, also lateral, confinement for a series of large two-ribbon flares originating from the core of the active region. The large initial separation of the flare ribbons, together with an almost absent growth in ribbon separation, suggests a confined reconnection site high up in the corona. Based on a detailed analysis of the confined X1.6 flare on October 22, we show how exceptional the flaring of this active region was. We provide evidence for repeated energy release, indicating that the same magnetic field structures were repeatedly involved in magnetic reconnection. We find that a large number of electrons was accelerated to non-thermal energies, revealing a steep power law spectrum, but that only a small fraction was accelerated to high energies. The total non-thermal energy in electrons derived (on the order of 10^25 J) is considerably higher than that in eruptive flares of class X1, and corresponds to about 10% of the excess magnetic energy present in the active-region corona. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.05157v1.pdf"}
{"id": "1502.06106", "abstract": "  We study the semilinear partial differential equation (PDE) associated with the non-linear BSDE characterizing buyer's and seller's XVA in a framework that allows for asymmetries in funding, repo and collateral rates, as well as for early contract termination due to counterparty credit risk. We show the existence of a unique classical solution to the PDE by first proving the existence and uniqueness of a viscosity solution and then its regularity. We use the uniqueness result to conduct a thorough numerical study illustrating how funding costs, repo rates, and counterparty credit risk contribute to determine the total valuation adjustment. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.06106v2.pdf"}
{"id": "1503.02297", "abstract": "  We discuss the nonlinear current of an interacting quantum dot coupled to normal and superconducting reservoirs with applied voltage and temperature differences. Due to the particle-hole symmetry introduced by the superconducting lead, the pure (subgap) thermoelectric response vanishes. However, we show that the Andreev bound states shift as the thermal gradient increases. As a consequence, the I–V characteristic can be tuned with a temperature bias if the system is simultaneously voltage biased. This is a cross effect that occurs beyond linear response only. Furthermore, we emphasize the role of quasiparticle tunneling processes in the generation of high thermopower sensitivities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.02297v1.pdf"}
{"id": "1503.02839", "abstract": "  We consider a wireless communication system in which N transmitter-receiver pairs want to communicate with each other. Each transmitter transmits data at a certain rate using a power that depends on the channel gain to its receiver. If a receiver can successfully receive the message, it sends an acknowledgment (ACK), else it sends a negative ACK (NACK). Each user aims to maximize its probability of successful transmission. We formulate this problem as a stochastic game and propose a fully distributed learning algorithm to find a correlated equilibrium (CE). In addition, we use a no regret algorithm to find a coarse correlated equilibrium (CCE) for our power allocation game. We also propose a fully distributed learning algorithm to find a Pareto optimal solution. In general Pareto points do not guarantee fairness among the users, therefore we also propose an algorithm to compute a Nash bargaining solution which is Pareto optimal and provides fairness among users. Finally, under the same game theoretic setup, we study these equilibria and Pareto points when each transmitter sends data at multiple rates rather than at a fixed rate. We compare the sum rate obtained at the CE, CCE, Nash bargaining solution and the Pareto point and also via some other well known recent algorithms. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.02839v4.pdf"}
{"id": "1503.08972", "abstract": "  The effects of mass imbalance in a three-component Hubbard model are studied by the dynamical mean-field theory combined with exact diagonalization. The model describes a fermion-fermion mixture of two different particle species with a mass imbalance. One species is two-component fermion particles, and the other is single-component ones. The local interaction between particle species is considered isotropically. It is found that the mass imbalance can drive the mixture from insulator to metal. The insulator-metal transition is a species-selective-like transition of lighter mass particles and occurs only at commensurate particle densities and moderate local interactions. For weak and strong local interactions the mass imbalance does not change the ground state of the mixture. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.08972v1.pdf"}
{"id": "1504.01368", "abstract": "  The overwhelming success of online social networks, the key actors in the Web 2.0 cosmos, has reshaped human interactions globally. To help understand the fundamental mechanisms which determine the fate of online social networks at the system level, we describe the digital world as a complex ecosystem of interacting networks. In this paper, we study the impact of heterogeneity in network fitnesses on the competition between an international network, such as Facebook, and local services. The higher fitness of international networks is induced by their ability to attract users from all over the world, which can then establish social interactions without the limitations of local networks. In other words, inter-country social ties lead to increased fitness of the international network. To study the competition between an international network and local ones, we construct a 1:1000 scale model of the digital world, consisting of the 80 countries with the most Internet users. Under certain conditions, this leads to the extinction of local networks; whereas under different conditions, local networks can persist and even dominate completely. In particular, our model suggests that, with the parameters that best reproduce the empirical overtake of Facebook, this overtake could have not taken place with a significant probability. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.01368v4.pdf"}
{"id": "1504.04249", "abstract": "  Studies of fixation dynamics in Markov processes predominantly focus on the mean time to absorption. This may be inadequate if the distribution is broad and skewed. We compute the distribution of fixation times in one-step birth-death processes with two absorbing states. These are expressed in terms of the spectrum of the process, and we provide different representations as forward-only processes in eigenspace. These allow efficient sampling of fixation time distributions. As an application we study evolutionary game dynamics, where invading mutants can reach fixation or go extinct. We also highlight the median fixation time as a possible analog of mixing times in systems with small mutation rates and no absorbing states, whereas the mean fixation time has no such interpretation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.04249v2.pdf"}
{"id": "1504.06744", "abstract": "  We study a generalisation of sabotage games, a model of dynamic network games introduced by van Benthem. The original definition of the game is inherently finite and therefore does not allow one to model infinite processes. We propose an extension of the sabotage games in which the first player (Runner) traverses an arena with dynamic weights determined by the second player (Saboteur). In our model of quantitative sabotage games, Saboteur is now given a budget that he can distribute amongst the edges of the graph, whilst Runner attempts to minimise the quantity of budget witnessed while completing his task. We show that, on the one hand, for most of the classical cost functions considered in the literature, the problem of determining if Runner has a strategy to ensure a cost below some threshold is EXPTIME-complete. On the other hand, if the budget of Saboteur is fixed a priori, then the problem is in PTIME for most cost functions. Finally, we show that restricting the dynamics of the game also leads to better complexity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.06744v2.pdf"}
{"id": "1504.07951", "abstract": "  The advantage of Pauli-Villars regularization in quantum field theory quantized on the light front is explained. Simple examples of scalar λφ^4 field theory and Yukawa-type model are used. We give also an example of nonperturbative calculation in the theory with Pauli-Villars fields, using for that a model of anharmonic oscillator modified by inclusion of ghost variables playing the role similar to Pauli-Villars fields. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.07951v1.pdf"}
{"id": "1505.04760", "abstract": "  The grand partition function of a model of confined quarks is exactly calculated at arbitrary temperatures and quark chemical potentials. The model is inspired by a softly BRST-broken version of QCD and possesses a quark mass function compatible with nonperturbative analyses of lattice simulations and Dyson-Schwinger equations. Even though the model is defined at tree level, we show that it produces a nontrivial and stable thermodynamic behaviour at any temperature or chemical potential. Results for the pressure, the entropy and the trace anomaly as a function of the temperature are qualitatively compatible with the effect of nonperturbative interactions as observed in lattice simulations. The finite density thermodynamics is also shown to contain nontrivial features, being far away from an ideal gas picture. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.04760v2.pdf"}
{"id": "1505.05044", "abstract": "  We report the propagation of high-intensity sound beams in a sonic crystal, under self-collimation or reduced-divergence conditions. The medium is a fluid with elastic quadratic nonlinearity, where the dominating nonlinear effect is harmonic generation. The conditions for the efficient generation of narrow, non-diverging beam of second harmonic are discussed. Numerical simulations are in agreement with the analytical predictions made, based on the linear dispersion characteristics in modulated media and the nonlinear interaction in a quadratic medium under phase matching conditions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.05044v1.pdf"}
{"id": "1505.05906", "abstract": "  The aim of this paper is to shed light on the topology and properties of the nodes (i.e. the zeros of the wave function) in electronic systems. Using the \"electrons on a sphere\" model, we study the nodes of two-, three- and four-electron systems in various ferromagnetic configurations (sp, p^2, sd, pd, p^3, sp^2 and sp^3). In some particular cases (sp, p^2, sd, pd and p^3), we rigorously prove that the non-interacting wave function has the same nodes as the exact (yet unknown) wave function. The number of atomic and molecular systems for which the exact nodes are known analytically is very limited and we show here that this peculiar feature can be attributed to interdimensional degeneracies. Although we have not been able to prove it rigorously, we conjecture that the nodes of the non-interacting wave function for the sp^3 configuration are exact. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.05906v1.pdf"}
{"id": "1505.06937", "abstract": "  The organization of interactions in complex systems can be described by networks connecting different units. These graphs are useful representations of the local and global complexity of the underlying systems. The origin of their topological structure can be diverse, resulting from different mechanisms including multiplicative processes and optimization. In spatial networks or in graphs where cost constraints are at work, as it occurs in a plethora of situations from power grids to the wiring of neurons in the brain, optimization plays an important part in shaping their organization. In this paper we study network designs resulting from a Pareto optimization process, where different simultaneous constraints are the targets of selection. We analyze three variations on a problem finding phase transitions of different kinds. Distinct phases are associated to different arrangements of the connections; but the need of drastic topological changes does not determine the presence, nor the nature of the phase transitions encountered. Instead, the functions under optimization do play a determinant role. This reinforces the view that phase transitions do not arise from intrinsic properties of a system alone, but from the interplay of that system with its external constraints. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.06937v2.pdf"}
{"id": "1505.07249", "abstract": "  Diffusion studies of adsorbates moving on a surface are often analyzed using 2D Langevin simulations. These simulations are computationally cheap and offer valuable insight into the dynamics, however, they simplify the complex interactions between the substrate and adsorbate atoms, neglecting correlations in the motion of the two species. The effect of this simplification on the accuracy of observables extracted using Langevin simulations was previously unquantified. Here we report a numerical study aimed at assessing the validity of this approach. We compared experimentally accessible observables which were calculated using a Langevin simulation with those obtained from explicit molecular dynamics simulations. Our results show that within the range of parameters we explored Langevin simulations provide a good alternative for calculating the diffusion procress, i.e. the effect of correlations is too small to be observed within the numerical accuracy of this study and most likely would not have a significant effect on the interpretation of experimental data. Our comparison of the two numerical approaches also demonstrates the effect temperature dependent friction has on the calculated observables, illustrating the importance of accounting for such a temperature dependence when interpreting experimental data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.07249v1.pdf"}
{"id": "1506.00596", "abstract": "  We perform full-potential screened-hybrid density-functional theory (DFT) calculations to compare the thermodynamic stability of neutral and charged states of the surface oxygen vacancy at the rutile TiO_2(110) surface. Solid-state (QM/MM) embedded-cluster calculations are employed to account for the strong TiO_2 polarization response to the charged defect states. Similar to the situation for the bulk O vacancy, the +2 charge state V_ O^2+ is found to be energetically by far most stable. Only for Fermi-level positions very close to the conduction band, small polarons may at best be trapped by the charged vacancy. The large decrease of the V_ O^2+ formation energy with decreasing Fermi-level position indicates strongly enhanced surface O vacancy concentrations for p-doped samples. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1506/1506.00596v1.pdf"}
{"id": "1506.02801", "abstract": "  We evaluate the distribution of waiting times between electrons emitted by a driven mesoscopic capacitor. Based on a wave packet approach we obtain analytic expressions for the electronic waiting time distribution and the joint distribution of subsequent waiting times. These semi-classical results are compared to a full quantum treatment based on Floquet scattering theory and good agreement is found in the appropriate parameter ranges. Our results provide an intuitive picture of the electronic emissions from the driven mesoscopic capacitor and may be tested in future experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1506/1506.02801v1.pdf"}
{"id": "1506.03833", "abstract": "  We consider the conductivity of excitations in short chains of optical cavities with two-level atoms in the models of JCH type, where either we explicitly take into account the photon jumps between atoms, or is merely a transfer of excitation from atom to atom. We found a non-trivial dependence of the conductivity on the intensity of runoff and inflow (quantum bottleneck) in the presence of dephasing noise (the effect of dephasing assisted transport). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1506/1506.03833v3.pdf"}
{"id": "1507.00222", "abstract": "  Random fluctuations of the shot-noise power in disordered graphene nanoribbons are studied. In particular, we calculate the distribution of the shot noise of nanoribbons with zigzag and armchair edge terminations. We show that the shot noise statistics is different for each type of these two graphene structures, which is a consequence of presence of different electron localizations: while in zigzag nanoribbons electronic edge states are Anderson localized, in armchair nanoribbons edge states are absent, but electrons are anomalously localized. Our analytical results are verified by tight binding numerical simulations with random hopping elements, i.e., off diagonal disorder, which preserves the symmetry of the graphene sublattices. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.00222v1.pdf"}
{"id": "1507.03363", "abstract": "  A laboratory hard X-ray photoelectron spectroscopy (HXPS) system equipped with a monochromatic Cr Kα (hν = 5414.7 eV) X-ray source was applied to an investigation of the core-level electronic structure of La_1-xSr_xMnO_3. No appreciable high binding-energy shoulder in the O 1s HXPS spectra were observed while an enhanced low binding-energy shoulder structure in the Mn 2p_3/2 HXPS spectra were observed, both of which are manifestation of high bulk sensitivity. Such high bulk sensitivity enabled us to track the Mn 2p_3/2 shoulder structure in the full range of x, giving us a new insight into the binding-energy shift of the Mn 2p_3/2 core level. Comparisons with the results using the conventional laboratory XPS (hν = 1486.6 eV) as well as those using a synchrotron radiation source (hν = 7939.9 eV) demonstrate that HXPS is a powerful and convenient tool to analyze the bulk electronic structure of a host of different compounds. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.03363v2.pdf"}
{"id": "1507.04380", "abstract": "  Simplified models of the dynamics such as the linear inverted pendulum model (LIPM) have proven to perform well for biped walking on flat ground. However, for more complex tasks the assumptions of these models can become limiting. For example, the LIPM does not allow for the control of contact forces independently, is limited to co-planar contacts and assumes that the angular momentum is zero. In this paper, we propose to use the full momentum equations of a humanoid robot in a trajectory optimization framework to plan its center of mass, linear and angular momentum trajectories. The model also allows for planning desired contact forces for each end-effector in arbitrary contact locations. We extend our previous results on LQR design for momentum control by computing the (linearized) optimal momentum feedback law in a receding horizon fashion. The resulting desired momentum and the associated feedback law are then used in a hierarchical whole body control approach. Simulation experiments show that the approach is computationally fast and is able to generate plans for locomotion on complex terrains while demonstrating good tracking performance for the full humanoid control. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.04380v1.pdf"}
{"id": "1507.06995", "abstract": "  We present a local sample (z<0.15) of 280 Star-Forming Compact Groups (SFCGs) of galaxies identified in the ultraviolet Galaxy Evolution EXplorer (GALEX) All-sky Imaging Survey (AIS). So far, just one prototypical example of SFCG, the Blue Infalling Group, has been studied in detail in the Local Universe. The sample of SFCGs is mainly the result of applying a Friends-of-Friends group finder in the space of celestial coordinates with a maximum linking-length of 1.5 arcmin and choosing groups with a minimum number of four members of bright UV-emitting 17<FUV<20.5 sources (mostly galaxies) from the GALEX/AIS catalogue. The result from the search are 280 galaxy groups composed by 226, 39, 11 and 4 groups of four, five, six and seven bright ultraviolet (UV) members, respectively. Only 59 of these 280 newly identified SFCGs have a previous catalogued group counterpart. Group redshifts are available for at least one member in 75", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.06995v1.pdf"}
{"id": "1507.07957", "abstract": "  We study the geometry of curves in the Minkowski space and in the de Sitter space, specially at points where the tangent direction is lightlike (i.e. has length zero) called lightlike points of the curve. We define the focal sets of these curves and study the metric structure of them. At the lightlike points, the focal set is not defined. We use singularity theory techniques to carry out our study and investigate the focal set near lightlike points. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.07957v2.pdf"}
{"id": "1508.00003", "abstract": "  We describe a Godunov-type magnetohydrodynamic (MHD) code based on the Miyoshi and Kusano (2005) solver which can be used to solve various astrophysical hydrodynamic and MHD problems. The energy equation is in the form of entropy conservation. The code has been implemented on several different coordinate systems: 2.5D axisymmetric cylindrical coordinates, 2D Cartesian coordinates, 2D plane polar coordinates, and fully 3D cylindrical coordinates. Viscosity and diffusivity are implemented in the code to control the accretion rate in the disk and the rate of penetration of the disk matter through the magnetic field lines. The code has been utilized for the numerical investigations of a number of different astrophysical problems, several examples of which are shown. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.00003v1.pdf"}
{"id": "1508.04683", "abstract": "  The previous paper [Veldhorst et al., J. Chem. Phys. 141, 054904 (2014)] demonstrated that the isomorph theory explains the scaling properties of a liquid of flexible chains consisting of ten Lennard-Jones particles connected by rigid bonds. We here investigate the same model with harmonic bonds. The introduction of harmonic bonds almost completely destroys the correlations in the equilibrium fluctuations of the potential energy and the virial. According to the isomorph theory, if these correlations are strong a system has isomorphs, curves in the phase diagram along which structure, dynamics and the excess entropy are invariant. The Lennard-Jones chain liquid with harmonic bonds does have curves in the phase diagram along which the structure and dynamics are invariant. The excess entropy is not invariant on these curves, which we refer to as \"pseudoisomorphs\". In particular this means that Rosenfeld's excess-entropy scaling (the dynamics being a function of excess entropy only) does not apply for the Lennard-Jones chain with harmonic bonds. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.04683v3.pdf"}
{"id": "1508.05875", "abstract": "  Fragmentation reactions induced on light and medium nuclei by protons and light nuclei of energies around 1 GeV/nucleon and below are studied with the Los Alamos transport code MCNP6 and with its CEM03.03 and LAQGSM03.03 event generators. CEM and LAQGSM assume that intermediate-energy fragmentation reactions on light nuclei occur generally in two stages. The first stage is the intranuclear cascade (INC), followed by the second, Fermi breakup disintegration of light excited residual nuclei produced after the INC. CEM and LAQGSM account also for coalescence of light fragments (complex particles) up to 4He from energetic nucleons emitted during INC. We investigate the validity and performance of MCNP6, CEM, and LAQGSM in simulating fragmentation reactions at intermediate energies and discuss possible ways of further improving these codes ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.05875v1.pdf"}
{"id": "1508.07046", "abstract": "  A 1-meter-long trapezoidal Triple-GEM detector with wide readout strips was tested in hadron beams at the Fermilab Test Beam Facility in October 2013. The readout strips have a special zigzag geometry and run along the radial direction with an azimuthal pitch of 1.37 mrad to measure the azimuthal phi-coordinate of incident particles. The zigzag geometry of the readout reduces the required number of electronic channels by a factor of three compared to conventional straight readout strips while preserving good angular resolution. The average crosstalk between zigzag strips is measured to be an acceptable 5.5", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.07046v2.pdf"}
{"id": "1509.00662", "abstract": "  The large number of close-in Jupiter-size exoplanets prompts the question whether star-planet interaction (SPI) effects can be detected. We focused our attention on the system HD 17156, having a Jupiter-mass planet in a very eccentric orbit. Here we present results of the XMM-Newton observations and of a five months coordinated optical campaign with the HARPS-N spectrograph. We observed HD 17156 with XMM-Newton when the planet was approaching the apoastron and then at the following periastron passage, quasi simultaneously with HARPS-N. We obtained a clear (≈ 5.5σ) X-ray detection only at the periastron visit, accompanied by a significant increase of the R'_ HK chromospheric index. We discuss two possible scenarios for the activity enhancement: magnetic reconnection and flaring or accretion onto the star of material tidally stripped from the planet. In any case, this is possibly the first evidence of a magnetic SPI effect caught in action. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.00662v2.pdf"}
{"id": "1509.02227", "abstract": "  We discuss the use of Langevin molecular dynamics in the investigation of the non-equilibrium properties of disordered vortex matter. Our special focus is set on values of system parameters that are realistic for disordered high-T_c superconductors such as YBCO. Using a discretized elastic line model, we study different aspects of vortices far from thermal equilibrium. On the one hand we investigate steady-state properties of driven magnetic flux lines in a disordered environment, namely the current-voltage characteristics, the gyration radius, and the pinning time statistics. On the other hand we study the complex relaxation processes and glassy-like dynamics that emerge in type-II superconductors due to the intricate competition between the long-range vortex-vortex repulsion and flux pinning due to randomly placed point defects. To this end we consider different types of sudden perturbations: temperature, magnetic field, and external current quenches. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.02227v2.pdf"}
{"id": "1510.01422", "abstract": "  Work in the classification literature has shown that in computing a classification function, one need not know the class membership of all observations in the training set; the unlabeled observations still provide information on the marginal distribution of the feature set, and can thus contribute to increased classification accuracy for future observations. The present paper will show that this scheme can also be used for the estimation of class prior probabilities, which would be very useful in applications in which it is difficult or expensive to determine class membership. Both parametric and nonparametric estimators are developed. Asymptotic distributions of the estimators are derived, and it is proven that the use of the unlabeled observations does reduce asymptotic variance. This methodology is also extended to the estimation of subclass probabilities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.01422v1.pdf"}
{"id": "1510.02955", "abstract": "  We analyze the recurrence-time statistics (RTS) in three-dimensional non-Hamiltonian volume preserving systems (VPS): an extended standard map, and a fluid model. The extended map is a standard map weakly coupled to an extra-dimension which contains a deterministic regular, mixed (regular and chaotic) or chaotic motion. The extra-dimension strongly enhances the trapping times inducing plateaus and distinct algebraic and exponential decays in the RTS plots. The combined analysis of the RTS with the classification of ordered and chaotic regimes and scaling properties, allows us to describe the intricate way trajectories penetrate the before impenetrable regular islands from the uncoupled case. Essentially the plateaus found in the RTS are related to trajectories that stay long times inside trapping tubes, not allowing recurrences, and then penetrates diffusively the islands (from the uncoupled case) by a diffusive motion along such tubes in the extra-dimension. All asymptotic exponential decays for the RTS are related to an ordered regime (quasi-regular motion) and a mixing dynamics is conjectured for the model. These results are compared to the RTS of the standard map with dissipation or noise, showing the peculiarities obtained by using three-dimensional VPS. We also analyze the RTS for a fluid model and show remarkable similarities to the RTS in the extended standard map problem. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.02955v1.pdf"}
{"id": "1510.07237", "abstract": "  We study unitarity and renormalizability in the Lifshitz scalar field theory, which is characterized by an anisotropic scaling between the space and time directions. Without the Lorentz symmetry, both the unitarity and the renormalizability conditions are modified from those in relativistic theories. We show that for renormalizability, an extended version of the power counting condition is required in addition to the conventional one. The unitarity bound for S-matrix elements also gives stronger constraints on interaction terms because of the reference frame dependence of scattering amplitudes. We prove that both unitarity and renormalizability require identical conditions as in the case of conventional relativistic theories. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.07237v1.pdf"}
{"id": "1510.07360", "abstract": "  We study the interacting self-avoiding trail (ISAT) model on a Bethe lattice of general coordination q and on a Husimi lattice built with squares and coordination q=4. The exact grand-canonical solutions of the model are obtained, considering that up to K monomers can be placed on a site and associating a weight ω_i for a i-fold visited site. Very rich phase diagrams are found with non-polymerized (NP), regular polymerized (P) and dense polymerized (DP) phases separated by lines (or surfaces) of continuous and discontinuous transitions. For Bethe lattice with q=4 and K=2, the collapse transition is identified with a bicritical point and the collapsed phase is associated to the dense polymerized phase (solid-like) instead of the regular polymerized phase (liquid-like). A similar result is found for the Husimi lattice, which may explain the difference between the collapse transition for ISAT's and for interacting self-avoiding walks on the square lattice. For q=6 and K=3 (studied on the Bethe lattice only), a more complex phase diagram is found, with two critical planes and two coexistence surfaces, separated by two tricritical and two critical end-point lines meeting at a multicritical point. The mapping of the phase diagrams in the canonical ensemble is discussed and compared with simulational results for regular lattices. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.07360v1.pdf"}
{"id": "1510.07439", "abstract": "  The Software Development Life Cycle (SDLC) starts with eliciting requirements of the customers in the form of Software Requirement Specification (SRS). SRS document needed for software development is mostly written in Natural Language(NL) convenient for the client. From the SRS document only, the class name, its attributes and the functions incorporated in the body of the class are traced based on pre-knowledge of analyst. The paper intends to present a review on Object Oriented (OO) analysis using Natural Language Processing (NLP) techniques. This analysis can be manual where domain expert helps to generate the required diagram or automated system, where the system generates the required diagram, from the input in the form of SRS. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.07439v1.pdf"}
{"id": "1511.00127", "abstract": "  Base-pockets (non-complementary base-pairs) in a double-stranded DNA play a crucial role in biological processes. Because of thermal fluctuations, it can lower the stability of DNA, whereas, in case of DNA aptamer, small molecules e.g. adenosinemonophosphate(AMP), adenosinetriphosphate(ATP) etc, form additional hydrogen bonds with base-pockets termed as \"binding-pockets\", which enhance the stability. Using the Langevin Dynamics simulations of coarse grained model of DNA followed by atomistic simulations, we investigated the influence of base-pocket and binding-pocket on the stability of DNA aptamer. Striking differences have been reported here for the separation induced by temperature and force, which require further investigation by single molecule experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.00127v1.pdf"}
{"id": "1511.01905", "abstract": "  We discuss a possibility that the domain wall problem in the next-to-minimal supersymmetric standard model is alleviated without introducing a small explicit Z_3 breaking term by analyzing the evolution of the singlet scalar field within an inflationary paradigm. The singlet scalar field which explains the μ-term tracks a time-varying minimum of the effective potential after inflation and slowly rolls down to its global minimum if there exist sufficiently large negative Hubble-induced corrections on the effective potential for the singlet field, which arise through supergravity. As a consequence, the whole Universe is confined within a single domain during and after inflation, which prevents the formation of domain walls. This will further constrain the history of the early Universe along with the Higgs-singlet coupling. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.01905v2.pdf"}
{"id": "1511.05348", "abstract": "  The metallicity of the progenitor system producing a type Ia supernova (SN Ia) could play a role in its maximum luminosity, as suggested by theoretical predictions. We present an observational study to investigate if such a relationship there exists. Using the 4.2m WHT we have obtained intermediate-resolution spectroscopy data of a sample of 28 local galaxies hosting SNe Ia, for which distances have been derived using methods independent to those based on the own SN Ia parameters. From the emission lines observed in their optical spectrum, we derived the gas-phase oxygen abundance in the region where each SN Ia exploded. Our data show a trend, with a 80", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.05348v1.pdf"}
{"id": "1511.05987", "abstract": "  We consider communication problems in the setting of mobile agents deployed in an edge-weighted network. The assumption of the paper is that each agent has some energy that it can transfer to any other agent when they meet (together with the information it holds).   The paper deals with three communication problems: data delivery,convergecast and broadcast. These problems are posed for a centralized scheduler which has full knowledge of the instance.   It is already known that, without energy exchange, all three problems are NP-complete even if the network is a line. Surprisingly, if we allow the agents to exchange energy, we show that all three problems are polynomially solvable on trees and have linear time algorithms on the line. On the other hand for general undirected and directed graphs we show that these problems, even if energy exchange is allowed, are still NP-complete. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.05987v1.pdf"}
{"id": "1511.06621", "abstract": "  Currently available separability criteria for continuous-variable states are generally based on the covariance matrix of quadrature operators. The well-known separability criterion of Duan et al. [Phys. Rev. Lett. 84, 2722 (2000)] and Simon [Phys. Rev. Lett. 84, 2726 (2000)] , for example, gives a necessary and sufficient condition for a two-mode Gaussian state to be separable, but leaves many entangled non-Gaussian states undetected. Here, we introduce an improvement of this criterion that enables a stronger entanglement detection. The improved condition is based on the knowledge of an additional parameter, namely the degree of Gaussianity, and exploits a connection with Gaussianity-bounded uncertainty relations [Phys. Rev. A 86, 030102 (2012)]. We exhibit families of non-Gaussian entangled states whose entanglement remains undetected by the Duan-Simon criterion. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.06621v2.pdf"}
{"id": "1512.01261", "abstract": "  Two-dimensional transition metal dichalcogenides entwine interaction, spin-orbit coupling, and topology. Hole-doped systems lack spin degeneracy: states are indexed with spin and valley specificity. This unique structure offers new possibilities for correlated phases and phenomena. We realize an unconventional superconducting pairing phase which is an equal mixture of a spin singlet and the m = 0 spin triplet. It is stable against large in-plane magnetic fields, and its topology allows quasiparticle excitations of net nonzero Berry curvature via pair-breaking circularly polarized light. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.01261v3.pdf"}
{"id": "1512.01386", "abstract": "  We demonstrate that a phase-insensitive parametric amplifier, coupled to a quantum correlated source, can be used as a quantum information tap for noiseless three-way signal splitting. We find that the output signals are amplified noiselessly in two of the three output ports while the other can more or less keep its original input size without adding noise. This scheme is able to cascade and scales up for efficient information distribution in an optical network. Furthermore, we find this scheme satisfies the criteria for a non-ideal quantum non-demolition (QND) measurement and thus can serve as a QND measurement device. With two readouts correlated to the input, we find this scheme also satisfies the criterion for sequential QND measurement. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.01386v1.pdf"}
{"id": "1512.02749", "abstract": "  The entanglement properties of quenched quantum systems have been studied for a decade, however results in dimensions other than d=1 are generally lacking. We remedy this by investigating the entanglement properties of bosonic critical systems in d=3, both numerically and analytically, comparing the free and the interacting critical quench of an O(N) model. We find that the evolution of the entanglement entropy for these two systems is nearly identical, as expected from the \"quasi-particle\" picture. However, the low-lying entanglement spectrum is controlled by the different critical exponent of the two systems, and therefore these exponents may be extracted by purely entanglement-theoretic calculations. We verify this scaling numerically. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.02749v3.pdf"}
{"id": "1512.03102", "abstract": "  We report a dynamic light scattering study of the fluctuation modes in a thermotropic liquid crystalline mixture of monomer and dimer compounds that exhibits the twist-bend nematic (N_TB) phase. The results reveal a spectrum of overdamped fluctuations that includes two nonhydrodynamic and one hydrodynamic mode in the N_TB phase, and a single nonhydrodynamic plus two hydrodynamic modes (the usual nematic optic axis or director fluctuations) in the higher temperature, uniaxial nematic phase. The properties of these fluctuations and the conditions for their observation are comprehensively explained by a Landau-deGennes expansion of the free energy density in terms of heliconical director and helical polarization fields that characterize the N_TB structure, with the latter serving as the primary order parameter. A \"coarse-graining\" approximation simplifies the theoretical analysis, and enables us to demonstrate quantitative agreement between the calculated and experimentally determined temperature dependence of the mode relaxation rates. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.03102v1.pdf"}
{"id": "1512.03566", "abstract": "  It has been shown recently that relativistic distortions generate a dipolar modulation in the two-point correlation function of galaxies. To measure this relativistic dipole it is necessary to cross-correlate different populations of galaxies with for example different luminosities or colours. In this paper, we construct an optimal estimator to measure the dipole with multiple populations. We show that this estimator increases the signal-to-noise of the dipole by up to 35 percent. Using 6 populations of galaxies, in a survey with halos and number densities similar to those of the millennium simulation, we forecast a cumulative signal-to-noise of 4.4. For the main galaxy sample of SDSS at low redshift z<0.2 our optimal estimator predicts a cumulative signal-to-noise of 2.4. Finally we forecast a cumulative signal-to-noise of 7.4 in the upcoming DESI survey. These forecasts indicate that with the appropriate choice of estimator the relativistic dipole should be detectable in current and future surveys. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.03566v2.pdf"}
{"id": "1512.06737", "abstract": "  Infrared interferometric observations have a great deal of potential to unravel the nature of the nova eruptions. We suggest that techniques, already in place, to derive the ejection details at optical wavelengths be used with infrared interferometric observations to derive parameters such as the ejected mass in a nova eruption. This is achievable based on modelling the initial phase of the eruption when the infrared light is dominated by the free-free thermal process. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.06737v1.pdf"}
{"id": "1601.00140", "abstract": "  Borophene (two-dimensional boron sheet) is a new type of two-dimensional material, which was recently grown successfully on single crystal Ag substrates. In this paper, we investigate the electronic structure and bonding characteristics of borophene by first-principle calculations. The band structure of borophene shows highly anisotropic metallic behaviour. The obtained optical properties of borophene exhibit strong anisotropy as well. The combination of high optical transparency and high electrical conductivity in borophene makes it a promising candidate for future design of transparent conductors used in photovoltaics. Finally, the thermodynamic properties are investigated based on the phonon properties. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.00140v3.pdf"}
{"id": "1601.00501", "abstract": "  Introduced by Darwiche (2011), sentential decision diagrams (SDDs) are essentially as tractable as ordered binary decision diagrams (OBDDs), but tend to be more succinct in practice. This makes SDDs a prominent representation language, with many applications in artificial intelligence and knowledge compilation. We prove that SDDs are more succinct than OBDDs also in theory, by constructing a family of boolean functions where each member has polynomial SDD size but exponential OBDD size. This exponential separation improves a quasipolynomial separation recently established by Razgon (2013), and settles an open problem in knowledge compilation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.00501v1.pdf"}
{"id": "1601.05520", "abstract": "  We present a self-certifying compiler for the COGENT systems language. COGENT is a restricted, polymorphic, higher-order, and purely functional language with linear types and without the need for a trusted runtime or garbage collector. It compiles to efficient C code that is designed to interoperate with existing C functions. The language is suited for layered systems code with minimal sharing such as file systems or network protocol control code. For a well-typed COGENT program, the compiler produces C code, a high-level shallow embedding of its semantics in Isabelle/HOL, and a proof that the C code correctly implements this embedding. The aim is for proof engineers to reason about the full semantics of real-world systems code productively and equationally, while retaining the interoperability and leanness of C. We describe the formal verification stages of the compiler, which include automated formal refinement calculi, a switch from imperative update semantics to functional value semantics formally justified by the linear type system, and a number of standard compiler phases such as type checking and monomorphisation. The compiler certificate is a series of language-level meta proofs and per-program translation validation phases, combined into one coherent top-level theorem in Isabelle/HOL. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.05520v1.pdf"}
{"id": "1602.00859", "abstract": "  Data of physical contacts and face-to-face communications suggest temporally varying networks as the media on which infections take place among humans and animals. Epidemic processes on temporal networks are complicated by complexity of both network structure and temporal dimensions. Theoretical approaches are much needed for identifying key factors that affect dynamics of epidemics. In particular, what factors make some temporal networks stronger media of infection than other temporal networks is under debate. We develop a theory to understand the susceptible-infected-susceptible epidemic model on arbitrary temporal networks, where each contact is used for a finite duration. We show that temporality of networks lessens the epidemic threshold such that infections persist more easily in temporal networks than in their static counterparts. We further show that the Lie commutator bracket of the adjacency matrices at different times is a key determinant of the epidemic threshold in temporal networks. The effect of temporality on the epidemic threshold, which depends on a data set, is approximately predicted by the magnitude of a commutator norm. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.00859v2.pdf"}
{"id": "1602.01826", "abstract": "  We describe the relationship between dimer models on the real two-torus and coamoebas of curves in (^×)^2. We show, inter alia, that the dimer model obtained from the shell of the coamoeba is a deformation retract of the closed coaomeba if and only if the number of connected components of the complement of the closed coamoeba is maximal. Furthermore, we show that in general the closed coamoeba of the characteristic polynomial of a dimer model does not have the maximal number of components of its complement. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.01826v3.pdf"}
{"id": "1602.04698", "abstract": "  Graphs constructed to translate some graph problem into another graph problem are usually called auxiliary graphs. Specifically total graphs of simple graphs are used to translate the total colouring problem of the original graph into a vertex colouring problem of the transformed graph. In this paper, we obtain a new characterisation of total graphs of simple graphs. We also design algorithms to compute the inverse total graphs when the input graph is a total graph. These results improve over the work of Behzad, by using novel observations on the properties of the local structure in the neighbourhood of each vertex. The earlier algorithm was based on bfs and distances. Our theorems result in partitioning the vertex set of the total graph into the original graph and the line graph efficiently. We obtain constructive results for special classes, most notably for total graph of complete graphs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.04698v1.pdf"}
{"id": "1602.06047", "abstract": "  We investigate various types of squeezing in a collective su(2J+1) system consisting of spin-J particles (J>1/2). We show that the squeezing in the collective su(2J+1) system can be classified into unitary equivalence classes, each of which is characterized by a set of squeezed and anti-squeezed observables forming an su(2) subalgebra in the su(2J+1) algebra. The dimensionality of the unitary equivalence class is fundamentally related to its squeezing limit. We also demonstrate the classification of the squeezing among the spin and multipolar observables in a collective su(4) system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.06047v1.pdf"}
{"id": "1602.07691", "abstract": "  We propose an NMSSM scenario that can explain the excess in the diphoton spectrum at 750 GeV recently observed by ATLAS and CMS. We show that in a certain limit with a very light pseudoscalar one can reproduce the experimental results without invoking exotic matter. The 750 GeV excess is produced by two resonant heavy Higgs bosons with masses  750 GeV, that subsequently decay to two light pseudoscalars. Each of these decays to collimated photon pairs that appear as a single photon in the electromagnetic calorimeter. A mass gap between heavy Higgses mimics a large width of the 750 GeV peak. The production mechanism, containing a strong component via initial b quarks, ameliorates a possible tension with 8 TeV data compared to other production modes. We also discuss other constraints, in particular from low energy experiments. Finally, we discuss possible methods that could distinguish our proposal from other physics models describing the diphoton excess in the Run-II of the LHC. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.07691v2.pdf"}
{"id": "1602.07820", "abstract": "  In this article, we study the coherent pion production in neutrino-nucleus interaction in the resonance region using the formalism based on partially conserved axial current (PCAC) theorem which relates the neutrino-nucleus cross section to the pion-nucleus elastic cross section. The pion nucleus elastic cross section is calculated using the Glauber model in terms of pion-nucleon cross sections obtained by parameterizing the experimental data. We calculate the differential and integrated cross sections for charged current coherent pion production in neutrino carbon scattering. The results of integrated cross section calculations are compared with the measured data. Predictions for the differential and integrated cross sections for coherent pion productions in neutrino iron scattering using above formalism are also made. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.07820v2.pdf"}
{"id": "1602.08170", "abstract": "  With a test-particle simulation, we investigate the effect of large-scale coronal magnetic fields on electron acceleration at an outward-propagating coronal shock with a circular front. The coronal field is approximated by an analytical solution with a streamer-like magnetic field featured by partially open magnetic field and a current sheet at the equator atop the closed region. We show that the large-scale shock-field configuration, especially the relative curvature of the shock and the magnetic field line across which the shock is sweeping, plays an important role in the efficiency of electron acceleration. At low shock altitudes, when the shock curvature is larger than that of magnetic field lines, the electrons are mainly accelerated at the shock flanks; at higher altitudes, when the shock curvature is smaller, the electrons are mainly accelerated at the shock nose around the top of closed field lines. The above process reveals the shift of efficient electron acceleration region along the shock front during its propagation. It is also found that in general the electron acceleration at the shock flank is not so efficient as that at the top of closed field since at the top a collapsing magnetic trap can be formed. In addition, we find that the energy spectra of electrons is power-law like, first hardening then softening with the spectral index varying in a range of -3 to -6. Physical interpretations of the results and implications on the study of solar radio bursts are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.08170v1.pdf"}
{"id": "1602.08931", "abstract": "  A class of infinite horizon optimal control problems involving L^p-type cost functionals with 0<p≤ 1 is discussed. The existence of optimal controls is studied for both the convex case with p=1 and the nonconvex case with 0<p<1, and the sparsity structure of the optimal controls promoted by the L^p-type penalties is analyzed. A dynamic programming approach is proposed to numerically approximate the corresponding sparse optimal controllers. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.08931v1.pdf"}
{"id": "1603.03663", "abstract": "  In this work we study the entanglement entropy of a uniform quantum Ising chain in transverse field undergoing a periodic driving of period τ . By means of Floquet theory we show that, for any subchain, the entanglement entropy tends asymptotically to a value τ - periodic in time. We provide a semi-analytical formula for the leading term of this asymptotic regime: It is constant in time and obeys a volume law. The entropy in the asymptotic regime is always smaller than the thermal one: because of integrability the system locally relaxes to a Generalized Gibbs Ensemble (GGE) density matrix. The leading term of the asymptotic entanglement entropy is completely determined by this GGE density matrix. Remarkably, the asymptotic entropy shows marked features in correspondence to some non-equilibrium quantum phase transitions undergone by a Floquet state analog of the ground state. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.03663v3.pdf"}
{"id": "1603.05029", "abstract": "  By modelling heat engines as driven multi-partite system we show that their dissipation can be expressed in terms of the lag (relative entropy) between the perturbed state of each partition and their equilibrium state, and the correlations that build up among the partitions. We illustrate the rich interplay between correlations and lags with a two-qubit device driven by a quantum gate. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.05029v1.pdf"}
{"id": "1603.08848", "abstract": "  We study the masses of the low-lying charm and bottom mesons within the framework of heavy- hadron chiral perturbation theory (HHChPT). We work to third order in the chiral expansion, where meson loops contribute. In contrast to previous approaches, we use physical meson masses in evaluating these loops. This ensures that their imaginary parts are consistent with the observed widths of the D-mesons. The lowest odd- and even-parity, strange and nonstrange charm mesons provide enough constraints to determine only certain linear combinations of the low-energy constants (LECs) in the effective Lagrangian. We comment on how lattice QCD could provide further information to disentangle these constants. Then we use the results from the charm sector to predict the spectrum of odd- and even-parity of the bottom mesons. The predicted masses from our theory are in good agreement with experimentally measured masses for the case of the odd-parity sector. For the even-parity sector, the B-meson states have not yet been observed; thus, our results provide useful information for experimentalists investigating such states. The near degeneracy of nonstrange and strange scalar B mesons is confirmed in our predictions using HHChPT. We show why previous approaches of using HHChPT in studying the mass degeneracy in the scalar states of charm and bottom meson sectors gave unsatisfactory results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.08848v3.pdf"}
{"id": "1603.09691", "abstract": "  We calculate, in the context of a 3-3-1 model with heavy charged leptons, constraints on some parameters of the extra particles in the model by imposing that their contributions to both the electron and muon (g-2) factors are in agreement with experimental data up to 1σ-3σ. In order to obtain realistic results we use some of the possible solutions of the left- and right- unitary matrices that diagonalize the lepton mass matrices, giving the observed lepton masses and at the same time allowing to accommodate the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing matrix. We show that, at least up to 1-loop order, in the particular range of the space parameter that we have explored, it is not possible to fit the observed electron and muon (g-2) factors at the same time unless one of the extra leptons has a mass of the order of 20-40 GeVs and the energy scale of the 331 symmetry to be of around 60-80 TeVs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.09691v2.pdf"}
{"id": "1604.00837", "abstract": "  In this paper, we study factors that influence tag reuse behavior in social tagging systems. Our work is guided by the activation equation of the cognitive model ACT-R, which states that the usefulness of information in human memory depends on the three factors usage frequency, recency and semantic context. It is our aim to shed light on the influence of these factors on tag reuse. In our experiments, we utilize six datasets from the social tagging systems Flickr, CiteULike, BibSonomy, Delicious, LastFM and MovieLens, covering a range of various tagging settings. Our results confirm that frequency, recency and semantic context positively influence the reuse probability of tags. However, the extent to which each factor individually influences tag reuse strongly depends on the type of folksonomy present in a social tagging system. Our work can serve as guideline for researchers and developers of tag-based recommender systems when designing algorithms for social tagging environments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.00837v1.pdf"}
{"id": "1604.05589", "abstract": "  We investigate patterns of assortative matching on risk attitude, using self-reported (ordinal) data on risk attitudes for males and females within married couples, from the German Socio-Economic Panel over the period 2004-2012. We apply a novel copula-based bivariate panel ordinal model. Estimation is in two steps: firstly, a copula-based Markov model is used to relate the marginal distribution of the response in different time periods, separately for males and females; secondly, another copula is used to couple the males' and females' conditional (on the past) distributions. We find positive dependence, both in the middle of the distribution, and in the joint tails, and we interpret this as positive assortative matching (PAM). Hence we reject standard assortative matching theories based on risk-sharing assumptions, and favour models based on alternative assumptions such as the ability of agents to control income risk. We also find evidence of \"assimilation\"; that is, PAM appearing to increase with years of marriage. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.05589v3.pdf"}
{"id": "1605.04774", "abstract": "  In recent years researchers have gravitated to social media platforms, especially Twitter, as fertile ground for empirical analysis of social phenomena. Social media provides researchers access to trace data of interactions and discourse that once went unrecorded in the offline world. Researchers have sought to use these data to explain social phenomena both particular to social media and applicable to the broader social world. This paper offers a minireview of Twitter-based research on political crowd behavior. This literature offers insight into particular social phenomena on Twitter, but often fails to use standardized methods that permit interpretation beyond individual studies. Moreover, the literature fails to ground methodologies and results in social or political theory, divorcing empirical research from the theory needed to interpret it. Rather, papers focus primarily on methodological innovations for social media analyses, but these too often fail to sufficiently demonstrate the validity of such methodologies. This minireview considers a small number of selected papers; we analyze their (often lack of) theoretical approaches, review their methodological innovations, and offer suggestions as to the relevance of their results for political scientists and sociologists. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.04774v1.pdf"}
{"id": "1605.06379", "abstract": "  In structure-based models of proteins, one often assumes that folding is accomplished when all contacts are established. This assumption may frequently lead to a conceptual problem that folding takes place in a temperature region of very low thermodynamic stability, especially when the contact map used is too sparse. We consider six different structure-based models and show that allowing for a small, but model-dependent, percentage of the native contacts not being established boosts the folding temperature substantially while affecting the time scales of folding only in a minor way. We also compare other properties of the six models. We show that the choice of the description of the backbone stiffness has a substantial effect on the values of characteristic temperatures that relate both to equilibrium and kinetic properties. Models without any backbone stiffness (like the self-organized polymer) are found to perform similar to those with the stiffness, including in the studies of stretching. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.06379v1.pdf"}
{"id": "1606.05836", "abstract": "  Boson sampling, thought to be intractable classically, can be solved by a quantum machine composed of merely generation, linear evolution and detection of single photons. Such an analog quantum computer for this specific problem provides a shortcut to boost the absolute computing power of quantum computers to beat classical ones. However, the capacity bound of classical computers for simulating boson sampling has not yet been identified. Here we simulate boson sampling on the Tianhe-2 supercomputer which occupied the first place in the world ranking six times from 2013 to 2016. We computed the permanent of the largest matrix using up to 312,000 CPU cores of Tianhe-2, and inferred from the current most efficient permanent-computing algorithms that an upper bound on the performance of Tianhe-2 is one 50-photon sample per  100 min. In addition, we found a precision issue with one of two permanent-computing algorithms. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.05836v2.pdf"}
{"id": "1606.06623", "abstract": "  We investigate the integration of word embeddings as classification features in the setting of large scale text classification. Such representations have been used in a plethora of tasks, however their application in classification scenarios with thousands of classes has not been extensively researched, partially due to hardware limitations. In this work, we examine efficient composition functions to obtain document-level from word-level embeddings and we subsequently investigate their combination with the traditional one-hot-encoding representations. By presenting empirical evidence on large, multi-class, multi-label classification problems, we demonstrate the efficiency and the performance benefits of this combination. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.06623v1.pdf"}
{"id": "1606.07013", "abstract": "  We consider the dynamical atom-surface Casimir-Polder force in the non-equilibrium configuration of an atom near a perfectly conducting wall, initially prepared in an excited state with the field in its vacuum state. We evaluate the time-dependent Casimir-Polder force on the atom, and find that it shows an oscillatory behavior from attractive to repulsive both in time and in space. We also investigate the asymptotic behavior in time of the dynamical force and of related local field quantities, showing that the static value of the force, as obtained by a time-independent approach, is recovered for times much larger than the timescale of the atomic self-dressing, but smaller than the atomic decay time. We then discuss the evolution of global quantities such as atomic and field energies, and their asymptotic behavior. We also compare our results for the dynamical force on the excited atom with analogous results recently obtained for an initially bare ground-state atom. We show that new relevant features are obtained in the case of an initially excited atom, for example much larger values of the dynamical force with respect to the static one, allowing for an easier way to single-out and observe the dynamical Casimir-Polder effect. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.07013v2.pdf"}
{"id": "1606.08367", "abstract": "  We consider the full-duplex (FD) two-way amplify-and-forward relay system with imperfect cancelation of loopback self-interference (SI) and investigate joint design of relay and receive beamforming for minimizing the mean square error under a relay transmit power constraint. Due to loopback channel estimation error and limitation of analog-to-digital converter, the loopback SI cannot be completely canceled. Multiple antennas at the relay can help loopback SI suppression but beamforming is required to balance between the residual SI suppression and the desired signal transmission. Moreover, the relay beamforming matrix should be updated every time slot because the residual SI in the previous time slot is amplified by the current beamforming matrix and added to the received signals from the two sources in the current time slot. We derive the optimally balanced relay beamforming and receive beamforming matrices in closed form based on minimum mean square error, taking into account the propagation of the residual loopback SI from the first to the current time slot. We also propose beamforming design using only the channels of the m latest time slots, not from the first time slot. Based on our numerical results, we also identify when FD is beneficial and propose selection between FD and half-duplex according to signal-to-noise ratio and interference-to-noise ratio. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.08367v1.pdf"}
{"id": "1606.09372", "abstract": "  In this paper, we study the competition between finite-size effects (i.e. discernibility of particles) and dipole-dipole interactions in few-atom systems coupled to the electromagnetic field in vacuum. We consider two hallmarks of cooperative effects, superradiance and subradiance, and compute for each the rate of energy radiated by the atoms and the coherence of the atomic state during the time evolution. We adopt a statistical approach in order to extract the typical behavior of the atomic dynamics and average over random atomic distributions in spherical containers with prescribed k_0R with k_0 the radiation wavenumber and R the average interatomic distance. Our approach allows us to highlight the tradeoff between finite-size effects and dipole-dipole interactions in superradiance/subradiance. In particular, we show the existence of an optimal value of k_0R for which the superradiant intensity and coherence pulses are the less affected by dephasing effects induced by dipole-dipole interactions and finite-size effects. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.09372v2.pdf"}
{"id": "1607.00430", "abstract": "  Soft slender structures are ubiquitous in natural and artificial systems and can be observed at scales that range from the nanometric to the kilometric, from polymers to space tethers. We present a practical numerical approach to simulate the dynamics of filaments that, at every cross-section, can undergo all six possible modes of deformation, allowing the filament to bend, twist, stretch and shear, while interacting with complex environments via muscular activity, surface contact, friction and hydrodynamics. We examine the accuracy of our method by means of several benchmark problems with known analytic solutions. We then demonstrate the capabilities and robustness of our approach to solve forward problems in physics and mechanics related to solenoid and plectoneme formation in twisted, stretched filaments, and inverse problems related to active biophysics of limbless locomotion on solid surfaces and in bulk liquids. All together, our approach provides a robust computational framework to characterize the mechanical response and design of soft active slender structures. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1607/1607.00430v2.pdf"}
{"id": "1607.02299", "abstract": "  Motivated by original equipment manufacturer (OEM) service and maintenance practices we consider a single component subject to replacements at failure instances and two types of preventive maintenance opportunities: scheduled, which occur due to periodic system reviews of the equipment, and unscheduled, which occur due to failures of other components in the system. Modelling the state of the component appropriately and incorporating a realistic cost structure for corrective maintenance as well as condition-based maintenance (CBM), we derive the optimal CBM policy. In particular, we show that the optimal long-run average cost policy for the model at hand is a control-limit policy, where the control limit depends on the time until the next scheduled opportunity. Furthermore, we explicitly calculate the long-run average cost for any given control-limit time dependent policy and compare various policies numerically. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1607/1607.02299v1.pdf"}
{"id": "1607.08035", "abstract": "  We investigate the effect of variations in beam splitter transmissions and path length differences in the nonlinear sign gate that is used for linear optical quantum computing. We identify two implementations of the gate, and show that the sensitivity to variations in their components differs significantly between them. Therefore, circuits that require a precision implementation may benefit from additional circuit analysis of component variations to identify the most practical implementation. We suggest possible routes to efficient circuit analysis in terms of quantum parameter estimation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1607/1607.08035v1.pdf"}
{"id": "1607.08606", "abstract": "  Binary-star exoplanetary systems are now known to be common, for both wide and close binaries. However, their orbital evolution is generally unsolvable. Special cases of the N-body problem which are in fact completely solvable include dynamical architectures known as central configurations. Here, I utilize recent advances in our knowledge of central configurations to assess the plausibility of linking them to coplanar exoplanetary binary systems. By simply restricting constituent masses to be within stellar or substellar ranges characteristic of planetary systems, I find that (i) this constraint reduces by over 90 per cent the phase space in which central configurations may occur, (ii) both equal-mass and unequal-mass binary stars admit central configurations, (iii) these configurations effectively represent different geometrical extensions of the Sun-Jupiter-Trojan-like architecture, (iv) deviations from these geometries are no greater than ten degrees, and (v) the deviation increases as the substellar masses increase. This study may help restrict future stability analyses to architectures which resemble exoplanetary systems, and might hint at where observers may discover dust, asteroids and/or planets in binary star systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1607/1607.08606v1.pdf"}
{"id": "1608.00726", "abstract": "  We study unlimited infinite churn in peer-to-peer overlay networks. Under this churn, arbitrary many peers may concurrently request to join or leave the overlay network; moreover these requests may never stop coming. We prove that unlimited adversarial churn, where processes may just exit the overlay network, is unsolvable. We focus on cooperative churn where exiting processes participate in the churn handling algorithm. We define the problem of unlimited infinite churn in this setting. We distinguish the fair version of the problem, where each request is eventually satisfied, from the unfair version that just guarantees progress. We focus on local solutions to the problem, and prove that a local solution to the Fair Infinite Unlimited Churn is impossible. We then present and prove correct an algorithm UIUC that solves the Unfair Infinite Unlimited Churn Problem for a linearized peer-to-peer overlay network. We extend this solution to skip lists and skip graphs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.00726v1.pdf"}
{"id": "1608.04703", "abstract": "  In this work we present a four component relativistic theoretical investigation of the trihalides of lutetium and lawrencium, LuX3, LrX3 (X= F, Cl, Br, I) respectively using density functional theory (DFT) with different density functional and a geometrical optimisation procedure as implemented in DIRAC-package. The results show the trend of bonding from lighter to the heavier halide atoms and between 4f/5f atoms Lu and Lr. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.04703v1.pdf"}
{"id": "1608.05253", "abstract": "  We give a detailed account of the properties of spinning Ellis wormholes, supported by a phantom field. The general set of solutions depends on three parameters, associated with the size of the throat, the rotation and the symmetry of the solutions. For symmetric wormholes the global charges possess the same values in both asymptotic regions, while this is no longer the case for non-symmetric wormholes. We present mass formulae for these wormholes, study their quadrupole moments, and discuss the geometry of their throat and their ergoregion. We demonstrate, that these wormholes possess limiting configurations corresponding to an extremal Kerr black hole. Moreover, we analyze the geodesics of these wormholes, and show that they possess bound orbits. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.05253v1.pdf"}
{"id": "1609.00890", "abstract": "  Quaternionic Linear Canonical Transforms (QLCTs) are a family of integral transforms, which generalized the quaternionic Fourier transform and quaternionic fractional Fourier transform. In this paper, we extend the energy concentration problem for 2D hypercomplex signals (especially quaternionic signals). The most energy concentrated signals both in 2D spatial and quaternionic linear canonical frequency domains simultaneously are recently recognized to be the quaternionic prolate spheroidal wave functions (QPSWFs). The improved definitions of QPSWFs are studied which gave reasonable properties. The purpose of this paper is to understand the measurements of energy concentration in the 2D spatial and quaternionic linear canonical frequency domains. Examples of energy concentrated ratios between the truncated Gaussian function and QPSWFs intuitively illustrate that QPSWFs are more energy concentrated signals. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.00890v1.pdf"}
{"id": "1609.04407", "abstract": "  Together with interstellar turbulence, gravitation is one key player in star formation. It acts both at galactic scales in the assembly of gas into dense clouds, and inside those structures for their collapse and the formation of pre-stellar cores. To understand to what extent the large scale dynamics govern the star formation activity of galaxies, we present hydrodynamical simulations in which we generalise the behaviour of gravity to make it differ from Newtonian dynamics in the low acceleration regime. We focus on the extreme cases of interacting galaxies, and compare the evolution of galaxy pairs in the dark matter paradigm to that in the Milgromian Dynamics (MOND) framework. Following up on the seminal work by Tiret     Combes, this paper documents the first simulations of galaxy encounters in MOND with a detailed Eulerian hydrodynamical treatment of baryonic physics, including star formation and stellar feedback. We show that similar morphologies of the interacting systems can be produced by both the dark matter and MOND formalisms, but require a much slower orbital velocity in the MOND case. Furthermore, we find that the star formation activity and history are significantly more extended in space and time in MOND interactions, in particular in the tidal debris. Such differences could be used as observational diagnostics and make interacting galaxies prime objects in the study of the nature of gravitation at galactic scales. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.04407v1.pdf"}
{"id": "1609.05741", "abstract": "  We study mechanisms for wavenumber selection in a minimal model for run-and-tumble dynamics. We show that nonlinearity in tumbling rates induces the existence of a plethora of traveling- and standing-wave patterns, as well as a subtle selection mechanism for the wavenumbers of spatio-temporally periodic waves. We comment on possible implications for rippling patterns observed in colonies of myxobacteria. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.05741v2.pdf"}
{"id": "1609.06453", "abstract": "  The phenomenon of tumbling of microscopic objects is commonly associated with shear flows. We address the question of whether tumbling can also occur in stretching-dominated flows. To answer this, we study the dynamics of a semi-flexible trumbbell in a planar extensional velocity field. We show that the trumbbell undergoes a random tumbling-through-folding motion. The probability distribution of long tumbling times is exponential with a time scale exponentially increasing with the Weissenberg number. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.06453v2.pdf"}
{"id": "1609.08857", "abstract": "  We analyze theoretically and by means of molecular dynamics (MD) simulations the generation of mechanical force by a polyelectrolyte (PE) chain grafted to a plane. The PE is exposed to an external electric field that favors its adsorption on the plane. The free end of the chain is linked to a deformable target body. Varying the field one can alter the length of the non-adsorbed part of the chain. This entails variation of the deformation of the target body and hence variation of the arising in the body force. Our theoretical predictions for the generated force are in a very good agreement with the MD data. Using the developed theory for the generated force we study the effectiveness of possible PE-based nano-vices, comprised of two clenching planes connected by PEs and exposed to an external electric field. We exploit Cundall-Struck solid friction model to describe the friction between a particle and the clenching planes. We compute the self-diffusion coefficient of a clenched particle and show that it drastically decreases even in weak applied fields. This demonstrates the efficacy of the PE-based nano-vices, which may be a a possible alternative to the existing nano-tube nano-tweezers and optical tweezers. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.08857v1.pdf"}
{"id": "1609.09070", "abstract": "  Hydrogen and helium demix when sufficiently cool, and this bears on the evolution of all giant planets at large separations at or below roughly a Jupiter mass. We model the thermal evolution of Jupiter, including its evolving helium distribution following results of ab initio simulations for helium immiscibility in metallic hydrogen. After 4 Gyr of homogeneous evolution, differentiation establishes a thin helium gradient below 1 Mbar that dynamically stabilizes the fluid to convection. The region undergoes overstable double-diffusive convection (ODDC), whose weak heat transport maintains a superadiabatic temperature gradient. With a generic parameterization for the ODDC efficiency, the models can reconcile Jupiter's intrinsic flux, atmospheric helium content, and radius at the age of the solar system if the Lorenzen et al. H-He phase diagram is translated to lower temperatures. We cast the evolutionary models in an MCMC framework to explore tens of thousands of evolutionary sequences, retrieving probability distributions for the total heavy element mass, the superadiabaticity of the temperature gradient due to ODDC, and the phase diagram perturbation. The adopted SCvH-I equation of state favors inefficient ODDC such that a thermal boundary layer is formed, allowing the molecular envelope to cool rapidly while the deeper interior actually heats up over time. If the overall cooling time is modulated with an additional free parameter to imitate the effect of a colder or warmer EOS, the models favor those that are colder than SCvH-I. In this case the superadiabaticity is modest and a warming or cooling deep interior are equally likely. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.09070v1.pdf"}
{"id": "1609.09097", "abstract": "  Extensive observations from the Kepler spacecraft have recently revealed a new outburst phenomenon operating in cool pulsating DA (hydrogen atmosphere) white dwarfs (DAVs). With the introduction of two new outbursting DAVs from K2 Fields 7 (EPIC 229228364) and 8 (EPIC 220453225) in these proceedings, we presently know of six total members of this class of object. We present the observational commonalities of the outbursting DAVs: (1) outbursts that increase the mean stellar flux by up to 15", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.09097v1.pdf"}
{"id": "1610.01791", "abstract": "  Circumplanetary disks can be found around forming giant planets, regardless of whether core accretion or gravitational instability built the planet. We carried out state-of-the-art hydrodynamical simulations of the circumplanetary disks for both formation scenarios, using as similar initial conditions as possible to unveil possible intrinsic differences in the circumplanetary disk mass and temperature between the two formation mechanisms. We found that the circumplanetary disks mass linearly scales with the circumstellar disk mass. Therefore, in an equally massive protoplanetary disk, the circumplanetary disks formed in the disk instability model can be only a factor of eight more massive than their core-accretion counterparts. On the other hand, the bulk circumplanetary disk temperature differs by more than an order of magnitude between the two cases. The subdisks around planets formed by gravitational instability have a characteristic temperature below 100 K, while the core accretion circumplanetary disks are hot, with temperatures even greater than 1000 K when embedded in massive, optically thick protoplanetary disks. We explain how this difference can be understood as the natural result of the different formation mechanisms. We argue that the different temperatures should persist up to the point when a full-fledged gas giant forms via disk instability, hence our result provides a convenient criteria for observations to distinguish between the two main formation scenarios by measuring the bulk temperature in the planet vicinity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.01791v1.pdf"}
{"id": "1610.01878", "abstract": "  A new space-time discontinuous Galerkin (dG) method utilising special Trefftz polynomial basis functions is proposed and fully analysed for the scalar wave equation in a second order formulation. The dG method considered is motivated by the class of interior penalty dG methods, as well as by the classical work of Hughes and Hulbert. The choice of the penalty terms included in the bilinear form is essential for both the theoretical analysis and for the practical behaviour of the method for the case of lowest order basis functions. A best approximation result is proven for this new space-time dG method with Trefftz-type basis functions. Rates of convergence are proved in any dimension and verified numerically in spatial dimensions d = 1 and d = 2. Numerical experiments highlight the effectiveness of the Trefftz method in problems with energy at high frequencies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.01878v1.pdf"}
{"id": "1610.02643", "abstract": "  We present a universal method to include residual un-modeled background shape uncertainties in likelihood based statistical tests for high energy physics and astroparticle physics. This approach provides a simple and natural protection against mismodeling, thus lowering the chances of a false discovery or of an over constrained confidence interval, and allows a natural transition to unbinned space. Unbinned likelihood allows optimal usage of information for the data and the models, and enhances the sensitivity.   We show that the asymptotic behavior of the test statistic can be regained in cases where the model fails to describe the true background behavior, and present 1D and 2D case studies for model-driven and data-driven background models. The resulting penalty on sensitivities follows the actual discrepancy between the data and the models, and is asymptotically reduced to zero with increasing knowledge. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.02643v2.pdf"}
{"id": "1610.07183", "abstract": "  Due to the recent cases of algorithmic bias in data-driven decision-making, machine learning methods are being put under the microscope in order to understand the root cause of these biases and how to correct them. Here, we consider a basic algorithmic task that is central in machine learning: subsampling from a large data set. Subsamples are used both as an end-goal in data summarization (where fairness could either be a legal, political or moral requirement) and to train algorithms (where biases in the samples are often a source of bias in the resulting model). Consequently, there is a growing effort to modify either the subsampling methods or the algorithms themselves in order to ensure fairness. However, in doing so, a question that seems to be overlooked is whether it is possible to produce fair subsamples that are also adequately representative of the feature space of the data set - an important and classic requirement in machine learning. Can diversity and fairness be simultaneously ensured? We start by noting that, in some applications, guaranteeing one does not necessarily guarantee the other, and a new approach is required. Subsequently, we present an algorithmic framework which allows us to produce both fair and diverse samples. Our experimental results on an image summarization task show marked improvements in fairness without compromising feature diversity by much, giving us the best of both the worlds. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.07183v1.pdf"}
{"id": "1610.07989", "abstract": "  This report presents a submission to the Process Discovery Contest. The contest is dedicated to the assessment of tools and techniques that discover business process models from event logs. The objective is to compare the efficiency of techniques to discover process models that provide a proper balance between \"overfitting\" and \"underfitting\". In the context of the Process Discovery Contest, process discovery is turned into a classification task with a training set and a test set; where a process model needs to decide whether traces are fitting or not. In this report, we first show how we use two discovery techniques, namely: Inductive Miner and Decomposition, to discover process models from the training set using ProM tool. Second, we show how we use replay results to 1) check the rediscoverability of models, and to 2) classify unseen traces (in test logs) as fitting or not. Then, we discuss the classification results of validation logs, the complexity of discovered models, and their impact on the selection of models for submission. The report ends with the pictures of the submitted process models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.07989v1.pdf"}
{"id": "1610.08469", "abstract": "  Food and nutrition occupy an increasingly prevalent space on the web, and dishes and recipes shared online provide an invaluable mirror into culinary cultures and attitudes around the world. More specifically, ingredients, flavors, and nutrition information become strong signals of the taste preferences of individuals and civilizations. However, there is little understanding of these palate varieties. In this paper, we present a large-scale study of recipes published on the web and their content, aiming to understand cuisines and culinary habits around the world. Using a database of more than 157K recipes from over 200 different cuisines, we analyze ingredients, flavors, and nutritional values which distinguish dishes from different regions, and use this knowledge to assess the predictability of recipes from different cuisines. We then use country health statistics to understand the relation between these factors and health indicators of different nations, such as obesity, diabetes, migration, and health expenditure. Our results confirm the strong effects of geographical and cultural similarities on recipes, health indicators, and culinary preferences across the globe. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.08469v4.pdf"}
{"id": "1610.09876", "abstract": "  Phonons (collective atomic vibrations in solids) are more effective in transporting heat than photons. This is the reason why the conduction mode of heat transport in nonmetals (mediated by phonons) is dominant compared to the radiation mode of heat transport (mediated by photons). However, since phonons are unable to traverse a vacuum gap (unlike photons) it is commonly believed that two bodies separated by a gap cannot exchange heat via phonons. Recently, a mechanism was proposed by which phonons can transport heat across a vacuum gap - through Van der Waals interaction between two bodies with gap less than wavelength of light. Such heat transfer mechanisms are highly relevant for heating (and cooling) of nanostructures; the heating of the flying heads in magnetic storage disks is a case in point. Here, the theoretical derivation for modeling phonon transmission is revisited and extended to the case of two bodies made of different materials separated by a vacuum gap. Magnitudes of phonon transmission, and hence the heat transfer, for commonly used materials in the micro and nano-electromechanical industry are calculated and compared with the calculation of conduction heat transfer through air for small gaps. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.09876v1.pdf"}
{"id": "1611.02279", "abstract": "  We present a summary of the more than 3,000 sungrazing and near-Sun comets discovered in coronagraph images returned by the Solar and Heliospheric Observatory (SOHO), since its launch in December 1995. We address each of the four main populations of objects observed by SOHO: Kreutz (sungrazing) group, Meyer group, Marsden and Kracht (96P-Family) group, and non-group comets. Discussions for each group include basic properties, discovery statistics, and morphological appearance. In addition to updating the community on the status of the discoveries by SOHO, we also show that the rate of discovery of Kreutz sungrazers has likely remained static since approximately 2003, and report on the first likely fragmentation pair observed within the Meyer group. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.02279v1.pdf"}
{"id": "1611.03735", "abstract": "  In the present paper a theoretical interpretation of observational characteristics of the pulsar PSR J0540-6919 is suggested. In particular, we provide a theoretical model explaining the presence of two peaks in the radio domain and the brooding of these peaks at higher frequencies. The model also explains the pulse-phase coincidence of emission peaks at different frequencies and shows the physical, 'genetic' connection between the radio remission at frequencies of the order of GHz with gamma-ray emission up to GeV energies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.03735v2.pdf"}
{"id": "1611.04398", "abstract": "  The main objective of this study is the characterization of the velocity field in the Cygnus OB1 association using the radial velocity data currently available in the literature. This association is part of a larger star-forming complex located in the direction of the Cygnus region, but whose main subsystems may be distributed at different distances from the sun. We have collected radial velocity data for more than 300 stars in the area of 5 x 5 square degrees centred on the Cygnus OB1 association. We present the results of a kinematic clustering analysis in the subspace of the phase space formed by angular coordinates and radial velocity using two independent methodologies. We have found evidence of structure in the phase space with the detection of two main groups, corresponding to different radial velocity and distance values, belonging to the association, and associated with two main shells defined by the Halpha emission. A third grouping well separated from the other two in velocity appears to occupy the whole region associated with what has been called \"common shell\". ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.04398v1.pdf"}
{"id": "1611.06486", "abstract": "  We derive a set of modified Poisson-Nernst-Planck (mPNP) equations for ion transport from the variation of the free energy functional which includes the many-body Coulomb correlation in media of variable dielectric coefficient. The correlation effects are considered through the Debye charging process in which the self energy of an ion is governed by the generalized Debye-Hückel equation. We develop the asymptotic expansions of the self energy taking the ion radius as the small parameter such that the multiscale model can be solved efficiently by numerical methods. It is shown that the variations of the energy functional give the self-energy-modified PNP equations which satisfy a proper weak formulation. We present numerical results from different asymptotic expansions with a semi-implicit conservative numerical method and investigate the effect of the Coulomb correlation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.06486v2.pdf"}
{"id": "1611.09596", "abstract": "  We discuss the self-consistent dynamics of plasmas by means of hamiltonian formalism for a system of N near-resonant electrons interacting with a single Langmuir wave. The connection with the Vlasov description is revisited through the numerical calculation of the van Kampen-like eigenfrequencies of the linearized dynamics for many degrees of freedom. Both the exponential-like growth as well as damping of the Langmuir wave are shown to emerge from a phase mixing effect among beam modes, revealing unexpected similarities between the stable and unstable regimes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.09596v3.pdf"}
{"id": "1611.09979", "abstract": "  We use a pulsed nitrogen laser to produce atomic ions by laser ablation, measuring the relative ion yield for several elements, including some that have only recently been proposed for use in cold trapped ion experiments. For barium, we monitor the ion yield as a function of the number of applied ablation pulses for different substrates. We also investigate the ion production as a function of the pulse energy, and the efficiency of loading an ion trap as a function of radiofrequency voltage. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.09979v2.pdf"}
{"id": "1612.00359", "abstract": "  Weyl-Heisenberg ensembles are a class of determinantal point processes associated with the Schrödinger representation of the Heisenberg group. Hyperuniformity characterizes a state of matter for which (scaled) density fluctuations diminish towards zero at the largest length scales. We will prove that Weyl-Heisenberg ensembles are hyperuniform. Weyl-Heisenberg ensembles include as a special case a multi-layer extension of the Ginibre ensemble modeling the distribution of electrons in higher Landau levels, which has recently been object of study in the realm of the Ginibre-type ensembles associated with polyanalytic functions. In addition, the family of Weyl-Heisenberg ensembles includes new structurally anisotropic processes, where point-statistics depend on the different spatial directions, and thus provide a first means to study directional hyperuniformity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.00359v3.pdf"}
{"id": "1612.01376", "abstract": "  A tiny adiabatic-demagnetization refrigerator (T-ADR) has been developed for a commercial superconducting quantum interference device magnetometer [Magnetic Property Measurement System (MPMS) from Quantum Design]. The whole T-ADR system is fit in a cylindrical space of the diameter 8.5 mm and the length 250 mm, and can be inserted into the narrow sample tube of MPMS. A sorption pump is self-contained in T-ADR, and hence no complex gas handling system is necessary. With the single crystalline Gd_3Ga_5O_12 garnet (∼ 2 grams) used as a magnetic refrigerant, the routinely achievable lowest temperature is ∼ 0.56 K. The lower detection limit for a magnetization anomaly is ∼ 1 × 10^-7 emu, estimated from fluctuation of the measured magnetization. The background level is ∼ 5 × 10^-5 emu below 2 K at H = 100 Oe, which is largely attributable to a contaminating paramagnetic signal from the magnetic refrigerant. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.01376v1.pdf"}
{"id": "1612.05289", "abstract": "  Appealing to an analytical result from mean-field theory, we show, using a generic galaxy model, that galactic dynamo action can be suppressed by small-scale magnetic fluctuations. This is caused by the magnetic analogue of the Rädler or Ω× J effect, where rotation-induced corrections to the mean-field turbulent transport result in what we interpret to be an effective reduction of the standard α effect in the presence of small-scale magnetic fields. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.05289v3.pdf"}
{"id": "1612.05588", "abstract": "  We discuss collective excitations (both fundamental and solitonic excitations) of quantized superfluid vortices in neutron ^3P_2 superfluids, which likely exist in high density neutron matter such as neutron stars. Besides the well-known Kelvin modes (translational zero modes), we find a gapfull mode whose low-energy description takes the simple form of a double sine-Gordon model. The associated kink solution and its effects on spontaneous magnetization inside the vortex core are analyzed in detail. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.05588v2.pdf"}
{"id": "1612.05661", "abstract": "  Efficient phase cycling schemes remain a challenge for NMR techniques if the pulse sequences involve a large number of rf-pulses. Especially complex is the Carr Purcell Meiboom Gill (CPMG) pulse sequence where the number of rf-pulses can range from hundreds to several thousands. Our recent implementation of Magnetic Resonance Pore Imaging (MRPI) is based on a CPMG rf-pulse sequence in order to refocus the effect of internal gradients inherent in porous media. While the spin dynamics for spin-1/2 systems in CPMG like experiments are well understood it is still not straight forward to separate the desired pathway from the spectrum of unwanted coherence pathways. In this contribution we apply Phase Incremented Echo Train Acquisition (PIETA) to MRPI. We show how PIETA offers a convenient way to implement a working phase cycling scheme and how it allows one to gain deeper insights into the amplitudes of undesired pathways. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.05661v1.pdf"}
{"id": "1612.06100", "abstract": "  Fixed-wind unmanned aerial vehicles (UAVs) are essential for low cost aerial surveillance and mapping applications in remote regions. One of the main limitations of UAVs is limited fuel capacity and hence requires periodic refueling to accomplish a mission. The usual mechanism of commanding the UAV to return to a stationary base station for refueling can result in fuel wastage and inefficient mission operation time. Alternatively, unmanned gound vehicle (UGV) can be used as a mobile refueling unit where the UAV will rendezvous with the UGV for refueling. In order to accurately perform this task in the presence of wind disturbances, we need to determine an optimal trajectory in 3D taking UAV and UGV dynamics and kinematics into account. In this paper, we propose an optimal control formulation to generate a tunable UAV trajectory for rendezvous on a moving UGV taking wind disturbances into account. By a suitable choice of the value of an aggressiveness index in our problem setting, we are able to control the UAV rendezvous behavior. Several numerical results are presented to show the reliability and effectiveness of our approach. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.06100v2.pdf"}
{"id": "1612.06947", "abstract": "  We present the results of photometric observations of the mutual phenomena in the system of Galilean satellites obtained during 2014-2015. The observations were performed using the 26-inch refractor, Normal Astrograph, ZA-320 telescope of the Pulkovo Observatory (084) and MTM-500 telescope at Pulkovo mountain station at Kislovodsk (C20). We made observations a total of 72 phenomena. We had derived 51 light curves of good and medium quality for 34 events. The RMS of determining the brightness is within a range from 0.02 to 0.19 mag, the average RMS is 0.06 mag. This work was supported by RFBR grant (project 15-02-03025). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.06947v1.pdf"}
{"id": "1612.07485", "abstract": "  We theoretically investigate the dispersion relation of small-amplitude optical waves superimposing upon a beam of polarized monochromatic light propagating along a single-mode channel waveguide characterized by an instantaneous and spatially local Kerr nonlinearity. These small luminous fluctuations propagate along the waveguide as Bogoliubov elementary excitations on top of a one-dimensional dilute Bose quantum fluid evolve in time. They consequently display a strongly renormalized dispersion law, of Bogoliubov type. Analytical and numerical results are found in both the absence and the presence of one- and two-photon losses. Silicon and silicon-nitride waveguides are used as examples. We finally propose an experiment to measure this Bogoliubov dispersion relation, based on a stimulated four-wave mixing and interference spectroscopy techniques. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.07485v4.pdf"}
{"id": "1612.07802", "abstract": "  A symmetry-guided definition of time may enhance and simplify the analysis of historical series with recurrent patterns and seasonalities. By enforcing simple-scaling and stationarity of the distributions of returns, we identify a successful protocol of time definition in Finance. The essential structure of the stochastic process underlying the series can thus be analyzed within a most parsimonious symmetry scheme in which multiscaling is reduced in the quest of a time scale additive and independent of moment-order in the distribution of returns. At the same time, duration of periods in which markets remain inactive are properly quantified by the novel clock, and the corresponding (e.g., overnight) returns are consistently taken into account for financial applications. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.07802v2.pdf"}
{"id": "1612.08954", "abstract": "  We compute the entanglement entropy of a free massive Dirac field between two causally disconnected open charts in de Sitter space. We first derive the Bunch-Davies vacuum mode functions of the Dirac field. We find there exists no supercurvature mode for the Dirac field. We then give the Bogoliubov transformation between the Bunch-Davies vacuum and the open chart vacua that makes the reduced density matrix diagonal. We find that the Dirac field becomes more entangled than a scalar field as m^2/H^2 becomes small, and the difference is maximal in the massless limit. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.08954v1.pdf"}
{"id": "1612.09261", "abstract": "  Quantum communication over long distances is integral to information security and has been demonstrated in free space and fibre with two-dimensional polarisation states of light. Although increased bit rates can be achieved using high-dimensional encoding with spatial modes of light, the efficient detection of high-dimensional states remains a challenge to realise the full benefit of the increased state space. Here we exploit the entanglement between spatial modes and polarization to realise a four-dimensional quantum key distribution (QKD) protocol. We introduce a detection scheme which employs only static elements, allowing for the detection of all basis modes in a high-dimensional space deterministically. As a result we are able to realise the full potential of our high-dimensional state space, demonstrating efficient QKD at high secure key and sift rates, with the highest capacity-to-dimension reported to date. This work opens the possibility to increase the dimensionality of the state-space indefinitely while still maintaining deterministic detection and will be invaluable for long distance 'secure and fas' data transfer. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.09261v1.pdf"}
{"id": "1701.00296", "abstract": "  Strangeness signature of of quark-gluon plasma (QGP) is central to the exploration of baryon-dense matter: the search for the critical point and onset of deconfinement. I report on the discovery of QGP by means of strangeness: The key historical figures and their roles in this quest are introduced and the experimental results obtained are discussed. The important role of antihyperons is emphasized. The statistical hadronization model, and sudden hadronization are described. Results of present day data analysis: strangeness and entropy content of a large fireball, and the universal hadronization condition describing key features of all explored collision systems are presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.00296v2.pdf"}
{"id": "1701.01975", "abstract": "  Identification and alignment of three-dimensional folding of proteins may yield useful information about relationships too remote to be detected by conventional methods, such as sequence comparison, and may potentially lead to prediction of patterns and motifs in mutual structural fragments. With the exponential increase of structural proteomics data, the methods that scale with the rate of increase of data lose efficiency. Hence, new methods that reduce the computational expense of this problem should be developed. We present a novel framework through which we are able to find and align protein structure neighbors via hierarchical clustering and entropy-based query search, and present a web-based protein database search and alignment tool to demonstrate the applicability of our approach. The resulting method replicates the results of the current gold standard with a minimal loss in sensitivity in a significantly shorter amount of time, while ameliorating the existing web workspace of protein structure comparison with a customized and dynamic web-based environment. Our tool serves as both a functional industrial means of protein structure comparison and a valid demonstration of heuristics in proteomics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.01975v1.pdf"}
{"id": "1701.07305", "abstract": "  Precision measurements by the Alpha Magnetic Spectrometer (AMS-02) on the International Space Station of the primary cosmic-ray electron flux and the positron flux will be discussed. The electron flux and the positron flux each require a description beyond a single power-law spectrum. Both the electron flux and the positron flux change their behavior at  30 GeV but the fluxes are significantly different in their magnitude and energy dependence. Between 20 and 200 GeV the positron spectral index is significantly harder than the electron spectral index. The determination of the different behavior of the spectral indices versus energy is a new observation and provides important information on the origins of cosmic-ray electrons and positrons. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.07305v1.pdf"}
{"id": "1701.07702", "abstract": "  In this paper, the model of interaction is studied between f(T,𝒯) gravity and modified Chaplygin gas in FRW-flat metric. We obtain the Friedmann equations in the framework of teleparallel gravity by vierbein field. We consider that Universe dominates by components of cold matter, dark energy and modified Chaplygin gas. In what follows we separately write the corresponding continuity equations for components of Universe. Also, dark energy EoS and effective EoS are obtained with respect to redshift, thereafter the corresponding cosmological parameters are plotted in terms of redshift, thereinafter the accelerated expansion of the Universe is investigated. Finally, the stability of the model is discussed in phase plane analysis. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.07702v2.pdf"}
{"id": "1702.02336", "abstract": "  We investigate the helically-propagating edge states associated with pseudo-Landau levels in strained honeycomb lattices. We exploit chiral symmetry to derive a general criterion for the existence of these propagating edge states in the presence of only nearest-neighbour hoppings and we verify our criterion using numerical simulations of both uni-axially and trigonally strained honeycomb lattices. We show that the propagation of the helical edge state can be controlled by engineering the shape of the edges. Sensitivity to chiral-symmetry-breaking next-nearest-neighbour hoppings is assessed. Our result opens up an avenue toward the precise control of edge modes through manipulation of the edge shape. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.02336v2.pdf"}
{"id": "1702.02661", "abstract": "  We study the problem of ranking a set of items from nonactively chosen pairwise preferences where each item has feature information with it. We propose and characterize a very broad class of preference matrices giving rise to the Feature Low Rank (FLR) model, which subsumes several models ranging from the classic Bradley-Terry-Luce (BTL) (Bradley and Terry 1952) and Thurstone (Thurstone 1927) models to the recently proposed blade-chest (Chen and Joachims 2016) and generic low-rank preference (Rajkumar and Agarwal 2016) models. We use the technique of matrix completion in the presence of side information to develop the Inductive Pairwise Ranking (IPR) algorithm that provably learns a good ranking under the FLR model, in a sample-efficient manner. In practice, through systematic synthetic simulations, we confirm our theoretical findings regarding improvements in the sample complexity due to the use of feature information. Moreover, on popular real-world preference learning datasets, with as less as 10", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.02661v1.pdf"}
{"id": "1702.02813", "abstract": "  Because of their universal nature, Fano fluctuations are expected to influence the response of superconducting nanowire single-photon detectors (SNSPDs). We predict that photon counting rate (PCR) as a function of bias current (I_B) in SNSPDs is described by an integral over a transverse coordinate-dependent complementary error function. The latter describes smearing of local responses due to Fano fluctuations of the amount of energy deposited into electronic system. The finite width, σ, of the PCR vs I_B arises from fluctuations in the energy partition between quasiparticles and phonons during the energy down-conversion cascade. In narrow-nanowire SNSPDs the local responses are uniform, and the effect of Fano-fluctuations on σ is dominant. In wide-nanowire SNSPDs with strong coordinate dependence of local responses due to vortex-antivortex unbinding and vortex entry from edges, Fano-fluctuations smear singularities imprinted by vorticity on the transition part of PCR curve. We demonstrate good agreement between theory and experiments for a series of bath temperatures and photon energies in narrow-wire WSi SNSPDs. The time-resolved hotspot relaxation curves predicted by Fano fluctuations match the Lorentzian shapes observed in experiments over the whole range of bias currents investigated except for their tails. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.02813v1.pdf"}
{"id": "1702.04602", "abstract": "  We present a novel approach to computing transition probabilities in quantum field theory, which allows them to be written directly in terms of expectation values of nested commutators and anti-commutators of field operators, rather than squared matrix elements. We show that this leads to a diagrammatic expansion in which the retarded propagator plays a dominant role. As a result, one is able to see clearly how faster-than-light signalling is prevented between sources and detectors. Finally, we comment on potential implications of this approach for dealing with infra-red divergences. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.04602v1.pdf"}
{"id": "1702.04939", "abstract": "  In this paper we consider a network of agents monitoring a spatially distributed arrival process. Each node measures the number of arrivals seen at its monitoring point in a given time-interval with the objective of estimating the unknown local arrival rate. We propose an asynchronous distributed approach based on a Bayesian model with unknown hyperparameter, where each node computes the minimum mean square error (MMSE) estimator of its local arrival rate in a distributed way. As a result, the estimation at each node \"optimally\" fuses the information from the whole network through a distributed optimization algorithm. Moreover, we propose an ad-hoc distributed estimator, based on a consensus algorithm for time-varying and directed graphs, which exhibits reduced complexity and exponential convergence. We analyze the performance of the proposed distributed estimators, showing that they: (i) are reliable even in presence of limited local data, and (ii) improve the estimation accuracy compared to the purely decentralized setup. Finally, we provide a statistical characterization of the proposed estimators. In particular, for the ad-hoc estimator, we show that as the number of nodes goes to infinity its mean square error converges to the optimal one. Numerical Monte Carlo simulations confirm the theoretical characterization and highlight the appealing performances of the estimators. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.04939v1.pdf"}
{"id": "1702.05167", "abstract": "  The Hierarchical Schur Complement method (HSC), and the HSC-extension, have significantly accelerated the evaluation of the retarded Green's function, particularly the lesser Green's function, for two-dimensional nanoscale devices. In this work, the HSC-extension is applied to determine the solution of non-equilibrium Green's functions (NEGF) on three-dimensional nanoscale devices. The operation count for the HSC-extension is analyzed for a cuboid device. When a cubic device is discretized with N × N × N grid points, the state-of-the-art Recursive Green Function (RGF) algorithm takes 𝒪(N^7) operations, whereas the HSC-extension only requires 𝒪(N^6) operations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.05167v1.pdf"}
{"id": "1702.06042", "abstract": "  We study the thermoelectric properties and heat-to-work conversion performance of an interacting, multi-level quantum dot (QD) weakly coupled to electronic reservoirs. We focus on the sequential tunneling regime. The dynamics of the charge in the QD is studied by means of master equations for the probabilities of occupation. From here we compute the charge and heat currents in the linear response regime. Assuming a generic multi-terminal setup, and for low temperatures (quantum limit), we obtain analytical expressions for the transport coefficients which account for the interplay between interactions (charging energy) and level quantization. In the case of systems with two and three terminals we derive formulas for the power factor Q and the figure of merit ZT for a QD-based heat engine, identifying optimal working conditions which maximize output power and efficiency of heat-to-work conversion. Beyond the linear response we concentrate on the two-terminal setup. We first study the thermoelectric non-linear coefficients assessing the consequences of large temperature and voltage biases, focusing on the breakdown of the Onsager reciprocal relation between thermopower and Peltier coefficient. We then investigate the conditions which optimize the performance of a heat engine, finding that in the quantum limit output power and efficiency at maximum power can almost be simultaneously maximized by choosing appropriate values of electrochemical potential and bias voltage. At last we study how energy level degeneracy can increase the output power. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.06042v2.pdf"}
{"id": "1702.08053", "abstract": "  Tremendous growing demand for high data rate services such as video, gaming and social networking in wireless cellular systems, attracted researchers' attention to focus on developing proximity services. In this regard, device-to-device (D2D) communications as a promising technology for future cellular systems, plays crucial rule. The key factor in D2D communication is providing efficient peer discovery mechanisms in ultra dense networks. In this paper, we propose a centralized D2D discovery scheme by employing a signaling algorithm to exchange D2D discovery messages between network entities. In this system, potential D2D pairs share uplink cellular users' resources with collision detection, to initiate a D2D links. Stochastic geometry is used to analyze system performance in terms of success probability of the transmitted signal and minimum required time slots for the proposed discovery scheme. Extensive simulations are used to evaluate the proposed system performance. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.08053v1.pdf"}
{"id": "1703.01374", "abstract": "  This paper proposes a synthetic statistical top-down MIMO power line communications channel model based on a pure phenomenological approach. The basic idea consists of directly synthesizing the experimental channel statistical properties to obtain an extremely compact model that requires a small set of parameters. The model is derived from the analysis of the in-home 2 × 3 MIMO PLC channel data set obtained by the ETSI Specialist Task Force 410 measurement campaign in the band 1.8-100 MHz. The challenge of modeling the channel statistical correlation, exhibited among the frequencies and between the MIMO modes, in compact form is tackled and it is shown that a small set of parameters can be used to reconstruct such a correlation behavior. The model is validated and compared to the measured channels, showing a good agreement in terms of average channel gain, root-mean-square delay spread, coherence bandwidth, and channel capacity distribution. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.01374v1.pdf"}
{"id": "1703.01875", "abstract": "  JEM-EUSO is an international collaboration for the development of space–based Ultra High Energy Cosmic Ray (UHECR) detectors. The instrument consists of a wide Field Of View (FOV) camera for the detection of the UV light emitted by Extensive Air Showers (EAS) in the atmosphere. Within the JEM-EUSO framework several pathfinders have been developed or are in course of development: EUSO-TA, EUSO-Balloon, EUSO-SPB and Mini-EUSO. For the near future the K-EUSO detector is foreseen to detect cosmic rays from space. In this paper we present the JEM-EUSO project and give an overview of the pathfinders and of their results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.01875v1.pdf"}
{"id": "1703.05859", "abstract": "  Wireless powered communication network (WPCN) is a novel networking paradigm that uses radio frequency (RF) wireless energy transfer (WET) technology to power the information transmissions of wireless devices (WDs). When energy and information are transferred in the same frequency band, a major design issue is transmission scheduling to avoid interference and achieve high communication performance. Commonly used centralized scheduling methods in WPCN may result in high control signaling overhead and thus are not suitable for wireless networks constituting a large number of WDs with random locations and dynamic operations. To tackle this issue, we propose in this paper a distributed scheduling protocol for energy and information transmissions in WPCN. Specifically, we allow a WD that is about to deplete its battery to broadcast an energy request buzz (ERB), which triggers WET from its associated hybrid access point (HAP) to recharge the battery. If no ERB is sent, the WDs contend to transmit data to the HAP using the conventional p-persistent CSMA (carrier sensing multiple access). In particular, we propose an energy queueing model based on an energy decoupling property to derive the throughput performance. Our analysis is verified through simulations under practical network parameters, which demonstrate good throughput performance of the distributed scheduling protocol and reveal some interesting design insights that are different from conventional contention-based communication network assuming the WDs are powered with unlimited energy supplies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.05859v1.pdf"}
{"id": "1703.09116", "abstract": "  Eddy current flow meters (ECFM) are widely used for measuring the flow velocity of electrically conducting fluids. Since the flow induced perturbations of a magnetic field depend both on the geometry and the conductivity of the fluid, extensive calibration is needed to get accurate results. Transient eddy current flow metering (TECFM) has been developed to overcome this problem. It relies on tracking the position of an impressed eddy current system which is moving with the same velocity as the conductive fluid. We present an immersed version of this measurement technique and demonstrate its viability by numerical simulations and a first experimental validation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.09116v1.pdf"}
{"id": "1703.09661", "abstract": "  Density functional theory is used to describe electrolyte solutions in contact with electrodes of planar or spherical shape. For the electrolyte solutions we consider the so-called civilized model, in which all species present are treated on equal footing. This allows us to discuss the features of the electric double layer in terms of the differential capacitance. The model provides insight into the microscopic structure of the electric double layer, which goes beyond the mesoscopic approach studied in the accompanying paper. This enables us to judge the relevance of microscopic details, such as the radii of the particles forming the electrolyte solutions or the dipolar character of the solvent particles, and to compare the predictions of various models. Similar to the preceding paper, a general behavior is observed for small radii of the electrode in that in this limit the results become independent of the surface charge density and of the particle radii. However, for large electrode radii non-trivial behaviors are observed. Especially the particle radii and the surface charge density strongly influence the capacitance. From the comparison with the Poisson-Boltzmann approach it becomes apparent that the shape of the electrode determines whether the microscopic details of the full civilized model have to be taken into account or whether already simpler models yield acceptable predictions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.09661v1.pdf"}
{"id": "1703.10208", "abstract": "  We consider the large-time dynamics of one-dimensional processes involving adsorption and desorption of extended hard-core particles (dimers, trimers, ⋯,k-mers), while interacting through their constituent monomers. Desorption can occur whether or not these latter adsorbed together, which leads to reconstitution of k-mers and the appearance of sectors of motion with nonlocal conservation laws for k ≥ 3. Dynamic exponents of the sector including the empty chain are evaluated by finite-size scaling analyses of the relaxation times embodied in the spectral gaps of evolution operators. For attractive interactions it is found that in the low-temperature limit such time scales converge to those of the Glauber dynamics, thus suggesting a diffusive universality class for k ≥ 2. This is also tested by simulated quenches down to T=0 where a common scaling function emerges. By contrast, under repulsive interactions the low-temperature dynamics is characterized by metastable states which decay subdiffusively to a highly degenerate and partially jammed phase. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.10208v2.pdf"}
{"id": "astro-ph0001431", "abstract": "  We describe the design of a suite of software tools to allow users to query Gamma-Ray Burst (GRB) data and perform data mining expeditions. We call this suite of tools a shed (SHell for Expeditions using Datamining). Our schedule is to have a completed prototype (funded via the NASA AISRP) by February, 2002. Meanwhile, interested users will find a partially functioning tool shed at http://grb.mankato.msus.edu. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0001/0001431v1.pdf"}
{"id": "astro-ph0002250", "abstract": "  Most phenomenological galaxy formation models show a discrepancy between the predicted Tully-Fisher relation and the luminosity function. We show that this is mainly due to overmerging of galaxy haloes, which is inherent in both the Press-Schechter formalism and dissipationless N-body simulations. This overmerging problem be circumvented by including a specific galaxy halo formation recipe into an otherwise standard N-body code. Resolving the overmerging also allows us to include models for chemical evolution and starbursts, which improves the match to observational data and renders the modelling more realistic. We use high-redshift clustering data to try and distinguish models which predict similar results at low redshifts for different sets of parameters. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0002/0002250v1.pdf"}
{"id": "astro-ph0003119", "abstract": "  The physical conditions in the inner parsec of accretion disks believed to orbit the central black holes in active galactic nuclei can be probed by imaging the absorption of background radio emission by ionized gas in the disk. We report high angular resolution observations of the nearby galaxy NGC 4261 which show evidence for free-free absorption by a thin, nearly edge-on disk at several frequencies. The angular width, and probably the depth, of the absorption appears to increase with decreasing frequency, as expected. Because free-free absorption is much larger at lower frequencies, the longest possible baselines are needed to provide adequate angular resolution; observing at higher frequencies to improve resolution will not help. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0003/0003119v1.pdf"}
{"id": "astro-ph0003377", "abstract": "  We present the results of three-dimensional numerical simulations of mass transfer in semi-detached binary with a donor star whose rotation vector precesses around the orbital rotation axis of the binary in the observer's coordinate frame. The calculations support our previous model of flow without a `hot spot'. Characteristic features of the flow in this model, such as the formation of an circumbinary envelope, the absence of a `hot spot' at the edge of the accretion disk, and the formation of a shock wave along the edge of the stream, are also present in the solution for a binary with precessing donor star. The parameters of accretion disk and of the structure of the near-disk regions recur with the precessional period of the rotation axis of donor star. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0003/0003377v1.pdf"}
{"id": "astro-ph0007405", "abstract": "  We investigate the origin of the ubiquitous 0.5 - 10 Hz QPO in the Galactic microquasar GRS 1915+105. Using the archival X-ray data from RXTE, we make a wide band X-ray spectral fitting to the source during a low-hard state observed in 1999 June. We resolve the X-ray spectra into three components, namely a multi-color disk component, a Comptonised component and a power-law at higher energies. This spectral description is favored compared to other normally used spectra like a cut-off power law, hard components with reflection etc. We find that the 0.5 - 10 Hz QPO is predominantly due to variations in the Comptonised component. We use this result to constrain the location of the various spectral components in the source. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0007/0007405v1.pdf"}
{"id": "astro-ph0008153", "abstract": "  We use numerical simulations to study the development of gas/star offsets in the tidal tails of merging galaxies. These offsets are shown to be a natural consequence of the radially extended HI spatial distribution in disk galaxies, coupled with internal dissipation in the gaseous component driven by the interaction. This mechanism explains the observed gas/star offsets in interacting galaxies without invoking interactions with a hot (unseen) gaseous component. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0008/0008153v1.pdf"}
{"id": "astro-ph0010569", "abstract": "  We have studied a mass model for spiral galaxies in which the dark matter surface density is a scaled version of the observed HI surface density. Applying this mass model to a sample of 24 spiral galaxies with reliable rotation curves one obtains good fits for most galaxies. The scaling factors cluster around 7, after correction for the presence of primordial helium. But for several cases different, often larger, values are found. For galaxies that can not be fitted well the discrepancy occurs at large radii and results from a fairly rapid decline of the HI surface density in the outermost regions. Because of such imperfections and in view of possible selection effects it is not possible to conclude here that there is a real coupling between HI and dark matter in spiral galaxies. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0010/0010569v1.pdf"}
{"id": "astro-ph0104275", "abstract": "  We present a review of recent studies of the formation and evolution of the Milky Way galaxy, in particular based on large samples of non-kinematically selected stars with available proper motions. The Milky Way is argued to be a reasonable template for the formation of large spiral galaxies, the only one in which complete kinematical and abundance information can be readily obtained. Ongoing and future projects to obtain proper motions and spectral information for much larger samples of stars that will sharpen our perspective are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0104/0104275v1.pdf"}
{"id": "astro-ph0105121", "abstract": "  The orbits and physical parameters of three detached, double-lined A-F eclipsing binaries have been derived combining H_P, V_T, B_T photometry from the Hipparcos/Tycho mission with 8500-8750 Ang ground-based spectroscopy, mimicking the photometric+spectroscopic observations that should be obtained by GAIA, the approved Cornerstone 6 mission by ESA. This study has two main objectives, namely (a) to derive reasonable orbits for a number of new eclipsing binaries and (b) to evaluate the expected performances by GAIA on eclipsing binaries and the accuracy achievable on the determination of fundamental stellar parameters like masses and radii. It is shown that a 1", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0105/0105121v2.pdf"}
{"id": "astro-ph0105359", "abstract": "  We study the effect of non-radial motions on the mass function, the VDF and on the shape of clusters of galaxies using the model introduced in Del Popolo     Gambera (1998a,b; 1999). The mass function of clusters, obtained using the quoted model, is compared with the statistical data by Bahcall     Cen (1992) and Girardi et al. (1998), while the VDF is compared with the CfA data by Zabludoff et al. (1993) for local clusters. In both cases the model predictions are in good agreement with the observational data showing once more how non-radial motions can reduce many of the discrepancies between CDM model predictions and observational data. Besides we study the effect of non-radial motions on the intrinsic shape of clusters of galaxies showing that non-radial motions produce clusters less elongated with respect to CDM model. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0105/0105359v1.pdf"}
{"id": "astro-ph0109219", "abstract": "  We present a progress report of our wide field CCD survey of globular clusters in M31. We have covered 3 deg X 3 deg area centered on M31, using the KPNO 0.9m and Washington CMT1 filters. Our survey is much deeper and more sensitive than previous surveys. We have found several hundred new globular cluster candidates in M31 in addition to confirming previously known globular clusters, and also have found a number of interlopers among previous globular cluster catalogs. We have also obtained spectra of about 500 objects among these candidates using the HYDRA at the WIYN 3.5m telescope, which are used for classification and measuring the radial velocity of the candidate objects. When completed, a new master catalog of globular clusters in M31 will be made, combining the new globular clusters with the known globular clusters. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0109/0109219v1.pdf"}
{"id": "astro-ph0110580", "abstract": "  In this paper we extend Chandrasekhar and von Neumann's analysis of the statistics of the gravitational field to systems in which particles (e.g. stars, galaxies) are not homogeneously distributed. We derive a distribution function W(F,d F/dt) giving the joint probability that a test particle is subject to a force F and an associated rate of change of F given by d F/dt. We calculate the first moment of d F/dt to study the effects of inhomogenity on dynamical friction. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0110/0110580v1.pdf"}
{"id": "astro-ph0112152", "abstract": "  We present optical observations of the fields of two X-ray sources located near the center of the shell-like supernova remnant G266.1-1.2. No objects brighter than R 22.5 and B 23 are present within the small Chandra error region of AX J0851.9-4617.4, besides a R 17 star that has already been excluded as a possible counterpart. A bright diffuse H_alpha nebula is present close to the position of the candidate neutron star. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0112/0112152v1.pdf"}
{"id": "astro-ph0112215", "abstract": "  An XMM-Newton observation of the luminous Seyfert 1 galaxy 1H 0419-577 is presented. We find that the spectrum is well fitted by a power law of canonical slope (gamma   1.9) and 3 blackbody components (to model the strong soft excess). The XMM data are compared and contrasted with observations by ROSAT in 1992 and by ASCA and BeppoSAX in 1996. We find that the overall X-ray spectrum has changed substantially over the period, and suggest that the changes are driven by the soft X-ray component. When bright, as in our XMM-Newton observation, it appears that the enhanced soft flux cools the Comptonising corona, causing the 2-10 keV power law to assume a `typical' slope, in contrast to the unusually hard (`photon-starved') spectra observed by ASCA and BeppoSAX four years earlier. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0112/0112215v1.pdf"}
{"id": "astro-ph0112287", "abstract": "  We present results from two Chandra/ACIS observations of the so-called Vela “Bullet D” region on the eastern limb of the Vela supernova remnant. The Bullet D region is a bright X-ray feature, identified by Aschenbach et al. (1995) from the ROSAT All-Sky Survey, which protrudes beyond the blast wave on the eastern side of the remnant. It has been suggested that this feature is a fragment of supernova ejecta which is just now pushing beyond the position of the main blast wave. An alternate explanation is that the feature is a “break-out” of the shock in which inhomogeneities in the ambient medium cause the shock to be non-spherical. The Chandra image shows a fragmented, filamentary morphology within this region. The Chandra spectra show strong emission lines of O, Ne, and Mg. Equilibrium ionization models indicate that the O and Ne abundances are significantly enhanced compared to solar values. However, non-equilibrium ionization models can fit the data with solar O abundances and Ne abundances enhanced by only a factor of two. The Chandra data are more consistent with the shock breakout hypothesis, although they cannot exclude the fragment of ejecta hypothesis. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0112/0112287v1.pdf"}
{"id": "astro-ph0112463", "abstract": "  We decipher intrinsic three-dimensional shape distributions of molecular clouds, cloud cores, Bok globules, and condensations using recently compiled catalogues of observed axis ratios for these objects mapped in carbon monoxide, ammonia, through optical selection, or in continuum dust emission. We apply statistical techniques to compare assumed intrinsic axis ratio distributions with observed projected axis ratio distributions. Intrinsically triaxial shapes produce projected distributions which agree with observations. Molecular clouds mapped in ^12CO are intrinsically triaxial but more nearly prolate than oblate, while the smaller cloud cores, Bok globules, and condensations are also intrinsically triaxial but more nearly oblate than prolate. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0112/0112463v1.pdf"}
{"id": "astro-ph0203027", "abstract": "  We performed SPH simulations to study the nuclear morphology of a barred galaxy NGC 4314. We have constructed the mass models based on the results of a profile decomposition into disk, bulge, and bar components. Our models have three different nuclear structures according to the assumption about the nuclear bar: no nuclear bar, a synchronous nuclear bar and a fast nuclear bar. Our SPH simulations show that the morphology of the nuclear region of NGC 4314 which is characterized by an elongated ring/spiral of newly formed stars and HII regions, aligned nearly parallel to the primary bar can be understood in terms of the secular evolution driven by the non-axisymmetric potential. The slightly elongated and aligned nuclear ring of NGC 4314 can be formed by the strong barred potential and the moderate central concentration of the bulge mass with and without a nuclear bar. However, the nuclear spiral pattern can not be developed without a nuclear bar. The nuclear bar of NGC 4314 seems to rotate faster than the primary bar since the nuclear morphology induced by the synchronous nuclear bar is much different from the observed one. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0203/0203027v1.pdf"}
{"id": "astro-ph0204170", "abstract": "  We analyze the general radiation emission mechanism from a charged particle moving in a curved inhomogeneous magnetic field. The consideration of the gradient makes the curved vacuum magnetic field compatible with the Maxwell equations and adds a non-trivial term to the transverse drift velocity and, consequently, to the general radiation spectrum. To obtain the radiation spectrum in the classical domain a general expression for the spectral distribution and characteristic frequency of an electron in arbitrary motion is derived by using Schwinger's method. The radiation patterns of the ultrarelativistic electron are represented in terms of the acceleration of the particle. The same results can be obtained by considering that the motion of the electron can be formally described as an evolution due to magnetic and electric forces. By defining an effective electromagnetic field, which combines the magnetic field with the fictitious electric field associated to the curvature and drift motion, one can obtain all the physical characteristics of the radiation by replacing the constant magnetic field with the effective field. The power, angular distribution and spectral distribution of all three components (synchrotron, curvature and gradient) of the radiation are considered in both classical and quantum domain in the framework of this unified formalism. In the quantum domain the proposed approach allows the study of the effects of the inhomogeneities and curvature of the magnetic field on the radiative transitions rates of electrons between low-lying Landau levels and the ground state. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0204/0204170v1.pdf"}
{"id": "astro-ph0206095", "abstract": "  We present first results from a 325 ks observation of the Seyfert 1 galaxy MCG-6-30-15 with XMM-Newton and BeppoSAX. The strong, broad, skewed iron line is clearly detected and is well characterised by a steep emissivity profile within 6r_g (i.e. 6GM/c^2) and a flatter profile beyond. The inner radius of the emission appears to lie at about 2r_g, consistent with results reported from both an earlier XMM-Newton observation of MCG-6-30-15 by Wilms et al. and part of an ASCA observation by Iwasawa et al. when the source was in a lower flux state. The radius and steep emissivity profile do depend however on an assumed incident power-law continuum and a lack of complex absorption above 2.5 keV. The blue wing of the line profile is indented, either by absorption at about 6.7 keV or by a hydrogenic iron emission line. The broad iron line flux does not follow the continuum variations in a simple manner. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0206/0206095v1.pdf"}
{"id": "astro-ph0209162", "abstract": "  For the inflaton perturbations it is shown that the evolution of the difference between the spectral indices can be translated into information on the scale dependence of the tensor to scalar amplitudes ratio, r, and how the scalar field potential can be derived from that information. Examples are given where r converges to a constant value during inflation but dynamics are rather different from the power–law model. Cases are presented where a constant r is not characteristic of the inflationary dynamics though the resulting perturbation spectra are consistent with the CMB and LSS data.   The inflaton potential corresponding to r given by a n–th order polynomial of the e–folds number is derived in quadratures expressions. Since the observable difference between the spectral indices evaluated at a pivot scale yields information about the linear term of that polynomial, the first order case is explicitly written down. The solutions show features beyond the exponential form corresponding to power–law inflation and can be matched with current observational data. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0209/0209162v2.pdf"}
{"id": "astro-ph0211456", "abstract": "  We propose a new technique, the use of FBGs (fiber Bragg gratings), for accurate, easy and low cost wavelength calibration of GAIA, RAVE and follow-ups spectra at local Observatories. FBGs mark the spectra with absorption lines, freely defined in number and position during the fibers manufacturing. The process goes in parallel with the science exposure and through the same optical train and path, thus ensuring the maximum return in wavelength calibration accuracy. Plans to manufacture and test FBGs for the CaII/Paschen region are underway at the Astronomical Observatory of Padova. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0211/0211456v1.pdf"}
{"id": "astro-ph0301145", "abstract": "  We calculate the delay in the propagation of a light signal past a massive body that moves with speed v, under the assumption that the speed of propagation of the gravitational interaction c_g differs from that of light. Using the post-Newtonian approximation, we consider an expansion in powers of v/c beyond the leading “Shapiro” time delay effect, while working to first order only in Gm/c^2, and show that the altered propagation speed of the gravitational signal has no effect whatsoever on the time delay to first order in v/c beyond the leading term, although it will have an effect to second and higher order. We show that the only other possible effects of an altered speed c_g at this order arise from a modification of the parametrized post-Newtonian (PPN) coefficient α_1 of the metric from the value zero predicted by general relativity. Current solar-system measurements already provide tight bounds on such a modification. We conclude that recent measurements of the propagation of radio signals past Jupiter are sensitive to α_1, but are not directly sensitive to the speed of propagation of gravity. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0301/0301145v2.pdf"}
{"id": "astro-ph0301491", "abstract": "  Archetypal analysis represents each individual member of a set of data vectors as a mixture (a constrained linear combination) of the pure types or archetypes of the data set. The archetypes are themselves required to be mixtures of the data vectors. Archetypal analysis may be particularly useful in analysing data sets comprising galaxy spectra, since each spectrum is, presumably, a superposition of the emission from the various stellar populations, nebular emissions and nuclear activity making up that galaxy, and each of these emission sources corresponds to a potential archetype of the entire data set. We demonstrate archetypal analysis using sets of composite synthetic galaxy spectra, showing that the method promises to be an effective and efficient way to classify spectra. We show that archetypal analysis is robust in the presence of various types of noise. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0301/0301491v1.pdf"}
{"id": "astro-ph0304052", "abstract": "  The majority of nearby early-type galaxies contains detectable amounts of emission-line gas at their centers. The emission-line ratios and gas kinematics potentially form a valuable diagnostic of the nuclear activity and gravitational potential well. The observed central gas velocity dispersion often exceeds the stellar velocity dispersion. This could be due to either the gravitational potential of a black hole or turbulent shocks in the gas. Here we try to discriminate between these two scenarios. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0304/0304052v1.pdf"}
{"id": "astro-ph0305034", "abstract": "  We utilize the bulk viscosity of interacting strange quark matter to reevaluate the damping time scale. The presence of medium effect of bulk viscosity leads to a stronger damping of r-modes, which can be over an order of magnitude for realistic parameters. We find that the r-mode instability window is narrowed due to the medium effect, and hence when a pulsar reaches the instability window it will only slow down by gravitational wave emission to a period of 1.78msec instead of 2.5msec given by early estimate. As a theoretical upper rotation limit of pulsars, the period of 1.78msec is very close to the two most rapidly spinning pulsars known, with periods of about 1.6msec. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0305/0305034v1.pdf"}
{"id": "astro-ph0308300", "abstract": "  We propose the study of long-term variations in the Fe Kalpha line profile as a discriminator for binary black hole (BH) systems. The existence of a binary BH in the center of an active galaxy will produce a particular signature in the evolution of the line profile, as a result of disk precession. This signature is a periodic variation of the position of the blue edge of the profile, accompanied by periodic change of its intensity. We show that detection of the former is clearly within the observational capabilities of planned X-ray missions. Detecting a periodic variation of line profiles would provide the first direct evidence for precessing discs in active galactic nuclei, as opposed to the existing evidence supporting only the precession of jets. We apply these ideas to 3C 273. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0308/0308300v1.pdf"}
{"id": "astro-ph0309605", "abstract": "  Using the numerical data of MHD simulation for AGN jets based on our “sweeping magnetic twist model”, we calculated the Faraday rotation measure (FRM) and the Stokes parameters to compare with observations. We propose that the FRM distribution can be used to discuss the 3-dimensional structure of magnetic field around jets, together with the projected magnetic field derived from the Stokes parameters. In the present paper, we supposed the basic straight part of AGN jet, and used the data of axisymmetric simulation. The FRM distribution we derived has a general tendency to have gradient across the jet axis, which is due to the toroidal component of the helical magnetic field generated by the rotation of the accretion disk. This kind of gradient in the FRM distribution is actually observed in some AGN jets (e.g. Asada et al. 2002), which suggests helical magnetic field around the jets and thus supports our MHD model. Following this success, we are now extending our numerical observation to the wiggled part of the jets using the data of 3-dimensional simulation based on our model in the following paper. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0309/0309605v1.pdf"}
{"id": "astro-ph0403380", "abstract": "  We present a reanalysis of the X-ray data for RX J0720.4-3125 presented in Zane et al. (2002), using more data recently available from XMM-Newton and Chandra. This analysis also corrects the Rosat data used in that paper to the TDB time system, incorporates the revised XMM-Newton barycentric correction available since then, and corrects the definition of the instantaneous period in the maximum likelihood periodogramme search. However, we are now unable to find a single coherent period that is consistent with all Rosat, Chandra and XMM-Newton datasets. From an analysis of the separate datasets, we have derived limits on the period change of Pdot = 1.4+/-0.6x10^-13 s/s at 99", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0403/0403380v1.pdf"}
{"id": "astro-ph0403635", "abstract": "  We critically examine the theory of disk locking, which assumes that the angular momentum deposited on an accreting protostar is exactly removed by torques carried along magnetic field lines connecting the star to the disk. In this letter, we consider that the differential rotation between the star and disk naturally leads to an opening (i.e., disconnecting) of the magnetic field between the two. We find that this significantly reduces the spin-down torque on the star by the disk. Thus, disk-locking cannot account for the slow rotation (∼10", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0403/0403635v2.pdf"}
{"id": "astro-ph0404594", "abstract": "  The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) has been observing gamma-ray lines from the Sun and the Galaxy since its launch in February 2002. Here I summarize the status of RHESSI observations of solar lines (nuclear de-excitation, neutron capture, and positron annihilation), the lines of ^26Al and ^60Fe from the inner Galaxy, and the search for positron annihilation in novae. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0404/0404594v1.pdf"}
{"id": "astro-ph0407642", "abstract": "  This is the second of a series of papers investigating the oscillation properties of relativistic, non-selfgravitating tori orbiting around black holes. Extending the work done in a Schwarzschild background, we here consider the axisymmetric oscillations of vertically integrated tori in a Kerr spacetime. The tori are modeled with a number of different non-Keplerian distributions of specific angular momentum and we discuss how the oscillation properties depend on these and on the rotation of the central black hole. We first consider a local analysis to highlight the relations between acoustic and epicyclic oscillations in a Kerr spacetime and subsequently perform a global eigenmode analysis to compute the axisymmetric p modes. In analogy with what found in a Schwarzschild background, these modes behave as sound waves that are modified by rotation and are globally trapped in the torus. For constant distributions of specific angular momentum, the eigenfrequencies appear in a sequence 2:3:4:... which is essentially independent of the size of the disc and of the black hole rotation. For non-constant distributions of angular momentum, on the other hand, the sequence depends on the properties of the disc and on the spin of the black hole, becoming harmonic for sufficiently large tori. We also comment on how p modes could explain the high frequency quasi-periodic oscillations observed in low-mass X-ray binaries with a black hole candidate and the properties of an equivalent model in Newtonian physics. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0407/0407642v1.pdf"}
{"id": "astro-ph0408021", "abstract": "  We analyzed the shapes of Galactic open clusters by the star counting technique with the 2MASS star catalog database. Morphological parameters such as the ellipticity and size have been derived via stellar density distribution, weighed by clustering probability. We find that most star clusters are elongated, even for the youngest star clusters of a few million years old, which are located near to the Galactic disk. The shapes of young star clusters must reflect the conditions in the parental molecular clouds and during the cluster formation process. As an open cluster ages, stellar dynamics cause the inner part of the cluster to circularize, but the overall radius gets larger and the stellar density becomes sparser. We discuss how internal relaxation process competes with Galactic external perturbation during cluster evolution. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0408/0408021v1.pdf"}
{"id": "astro-ph0411334", "abstract": "  We address the problem of identifying remnants of satellite galaxies in the halo of our galaxy with Gaia data. We make use of N-body simulations of dwarf galaxies being disrupted in the halo of our galaxy combined with a Monte Carlo model of the Milky Way galaxy. The models are converted to a simulated Gaia catalogue containing a realistic number (∼10^8–10^9) of stars. The simulated catalogue can be used to study how to handle the large data set that Gaia will provide and to study issues such as how to best retrieve information on substructure in the Galactic halo. The techniques described are applicable to any set of N-body simulations of (parts of) the Galaxy. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0411/0411334v1.pdf"}
{"id": "astro-ph0411405", "abstract": "  We present an analysis of the distribution and strength of star formation in three nearby small galaxy systems, which are undergoing a weak interaction, a strong interaction, and a merging process, respectively. The galaxies in all systems present widespread star formation enhancements,as well as, in some cases, nuclear activity. In particular, for the two closest systems, we study the number-count, size, and luminosity distribution of H ii regions within the interacting galaxies, while for the more distant, merging system we analyze the general distribution of the Halpha emission across the system and its velocity field. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0411/0411405v1.pdf"}
{"id": "astro-ph0411567", "abstract": "  We investigate which practical constraints are imposed by foregrounds to the detection of the B-mode polarization generated by gravitational waves in the case of experiments of the type currently being planned. Because the B-mode signal is probably dominated by foregrounds at all frequencies, the detection of the cosmological component depends drastically on our ability for removing foregrounds. We provide an analytical expression to estimate the level of the residual polarization for Galactic foregrounds, according to the method employed for their subtraction. We interpret this result in terms of the lower limit of the tensor-to-scalar ratio r that allows to disentangle the cosmological B-mode polarization from the foregrounds contribution. Polarized emission from extragalactic radio sources and gravitational lensing is also taken into account. As a first approach, we consider the ideal limit of an instrumental noise–free experiment: for a full–sky coverage and a degree resolution, we obtain a limit of r 10^(-4). This value can be improved by high–resolution experiments and, in principle, no clear fundamental limit on the detectability of gravitational waves polarization is found. Our analysis is also applied to planned or hypothetical future polarization experiments, taking into account expected noise levels. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0411/0411567v2.pdf"}
{"id": "astro-ph0501456", "abstract": "  We propose a model to explain a puzzling 3:2 frequency ratio of high frequency quasi-periodic oscillations (HFQPOs) in black hole (BH) X-ray binaries, GRO J1655-40, GRS 1915+105 and XTE J1550-564. In our model a non-axisymmetric magnetic coupling (MC) of a rotating black hole (BH) with its surrounding accretion disc coexists with the Blandford-Znajek (BZ) process. The upper frequency is fitted by a rotating hotspot near the inner edge of the disc, which is produced by the energy transferred from the BH to the disc, and the lower frequency is fitted by another rotating hotspot somewhere away from the inner edge of the disc, which arises from the screw instability of the magnetic field on the disc. It turns out that the 3:2 frequency ratio of HFQPOs in these X-ray binaries could be well fitted to the observational data with a much narrower range of the BH spin. In addition, the spectral properties of HFQPOs are discussed. The correlation of HFQPOs with jets from microquasars is contained naturally in our model. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0501/0501456v1.pdf"}
{"id": "astro-ph0501465", "abstract": "  We report on BVI CCD photometry of a field centered in the region of the Galactic star cluster Whiting 1 down to V=23.0. This cluster has never been studied insofar, and we provide for the first time estimates of its fundamental parameters, namely, radial extent, age, distance and reddening. Whiting 1 turns out to be a compact star cluster with a diameter of about 1^'. We find that the cluster is about 5 Gyr old and has a probable metal abundance around [Fe/H]= -1.20. Its position at b=-60^o.64 and at a heliocentric distance of about 45 kpc makes the cluster a rather strange object, surely not a disk old open cluster, but perhaps the youngest halo Globular Cluster insofar known. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0501/0501465v1.pdf"}
{"id": "astro-ph0503017", "abstract": "  The Cosmic Infrared Background (CIB) peaks in the Far-Infrared (FIR), and its Spectral Energy Distribution (SED) is now well constrained. Thanks to recent facilities and Spitzer, the populations contributing to the CIB are being characterized: the dominant galaxy contributions to the FIR CIB are Luminous IR galaxies (LIRGs) at 0.5<z<1.5 and, to the submm CIB, Ultra-LIRGs at z>2. These populations of galaxies experience very high rates of evolution with redshift. Because of confusion, the CIB is (and will remain in some domains) partially resolved and its contributing galaxies SEDs are not well constrained. We discuss all these aspects and show how confusion limits Spitzer observations, and how to overcome it in order to study the unresolved part of the CIB. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0503/0503017v1.pdf"}
{"id": "astro-ph0503601", "abstract": "  A reduced proper motion diagram utilizing Sloan Digital Sky Survey (SDSS) photometry and astrometry and USNO-B plate astrometry is used to separate cool white dwarf candidates from metal-weak, high-velocity main sequence Population II stars (subdwarfs) in the SDSS Data Release 2 imaging area. Follow-up spectroscopy using the Hobby-Eberly Telescope, the MMT, and the McDonald 2.7m Telescope is used to demonstrate that the white dwarf and subdwarf loci separate cleanly in the reduced proper motion diagram, and that the contamination by subdwarfs is small near the cool white dwarf locus. This enables large statistically complete samples of white dwarfs, particularly the poorly understood cool white dwarfs, to be created from the SDSS imaging survey, with important implications for white dwarf luminosity function studies. SDSS photometry for our sample of cool white dwarfs is compared to current white dwarf models. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0503/0503601v1.pdf"}
{"id": "astro-ph0506494", "abstract": "  HST and FUSE have provided high signal-to-noise, high-resolution spectra of a variety of cataclysmic variables and have allowed a detailed characterization of FUV emission sources in both high and low states. Here, I describe how this has advanced our understanding of non-magnetic CVs and the substantial interpretive challenges still posed by the observations. In the high state, the FUV spectra are dominated by disk emission that is modified by scattering in high and low velocity material located above the disk photosphere. Progress is being made toward reproducing the high-state spectra using kinematic prescriptions of the velocity field and new ionization and radiative transfer codes. In conjunction with hydrodynamical simulations of the outflows, accurate estimates of the mass loss rates and determination of the launching mechanism are likely forthcoming. In quiescence, the FUV spectra reveal contributions from the WD and the disk. Quantitative analyses have lead to solid measurements of the temperatures and abundances of a number of WDs in CVs, and of a determination of the response of the WD to an outburst. Basic challenges exist in terms of understanding the other components of the emission in quiescence, however, and these are needed to better understand the structure of the disk and the physical mechanisms resulting in ongoing accretion in quiescence. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0506/0506494v1.pdf"}
{"id": "astro-ph0508403", "abstract": "  Increasingly large populations of disk galaxies are now being observed at increasingly high redshifts, providing new constraints on our knowledge of how such galaxies evolve. Are these observations consistent with a cosmology in which structures form hierarchically? To probe this question, we employ SPH/N-body galaxy scale simulations of late-type galaxies. We examine the evolution of these simulated disk galaxies from redshift 1 to 0, looking at the mass-size and luminosity-size relations, and the thickness parameter, defined as the ratio of scale-height to scale-length. The structural parameters of our simulated disks settle down quickly, and after redshift z=1 the galaxies evolve to become only slightly flatter. Our present day simulated galaxies are larger, more massive, less bright, and redder than at z=1. The inside-out nature of the growth of our simulated galaxies reduces, and perhaps eliminates, expectations of evolution in the size-mass relation. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0508/0508403v2.pdf"}
{"id": "astro-ph0509672", "abstract": "  Recent observations and theories suggest that extreme horizontal branch (EHB) stars and their progeny should be the cause of the UV excess seen in the spectra of many elliptical galaxies. Since the Galactic Bulge is the closest representation of an old, metal-rich spheroid in which we are able to study the EHB scenario in detail, we obtained spectra of bulge EHB star candidates and we confirm their status as hot evolved stars. It is the first time that such stars are unambiguously identified in the Galactic Bulge. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0509/0509672v1.pdf"}
{"id": "astro-ph0510436", "abstract": "  We report on the search for planets orbiting 46 nearby young stars performed at the State Observatory of Turingia (TLS) by means of a radial velocity survey. The aim of this program is to test the theories of formation/evolution of planetary systems. For 19(8) stars we can exclude planets with Msini > 1 MJ (5 MJ) and P < 10 days; we find 1 short period binary and 5 stars with long period RV-trend. One good young exo-planet candidate is presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0510/0510436v1.pdf"}
{"id": "astro-ph0512322", "abstract": "  I review here the results of the first RV survey for spectroscopic companions to very young brown dwarfs (BDs) and (very) low-mass stars in the ChaI star-forming cloud with UVES at the VLT. This survey studies the binary fraction in an as yet unexplored domain not only in terms of primary masses (substellar regime) and ages (a few Myr) but also in terms of companion masses (sensitive down to planetary masses) and separations (< 1 AU). The UVES spectra obtained so far hint at spectroscopic companions of a few Jupiter masses around one BD and around one low-mass star (M4.5) with orbital periods of at least several months. Furthermore, the data indicate a multiplicity fraction consistent with field BDs and stellar binaries for periods < 100 days. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0512/0512322v1.pdf"}
{"id": "astro-ph0601124", "abstract": "  We present a non-parametric technique to infer the projected-mass distribution of a gravitational lens system with multiple strong-lensed images. The technique involves a dynamic grid in the lens plane on which the mass distribution of the lens is approximated by a sum of basis functions, one per grid cell. We used the projected mass densities of Plummer spheres as basis functions. A genetic algorithm then determines the mass distribution of the lens by forcing images of a single source, projected back onto the source plane, to coincide as well as possible. Averaging several tens of solutions removes the random fluctuations that are introduced by the reproduction process of genomes in the genetic algorithm and highlights those features common to all solutions. Given the positions of the images and the redshifts of the sources and the lens, we show that the mass of a gravitational lens can be retrieved with an accuracy of a few percent and that, if the sources sufficiently cover the caustics, the mass distribution of the gravitational lens can also be reliably retrieved. A major advantage of the algorithm is that it makes full use of the information contained in the radial images, unlike methods that minimise the residuals of the lens equation, and is thus able to accurately reconstruct also the inner parts of the lens. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0601/0601124v1.pdf"}
{"id": "astro-ph0607224", "abstract": "  We present the results of numerical experiments, in which we study how the asphericities induced by the growth of the standing accretion shock instability (SASI) produce the gravitational waveforms in the postbounce phase of core-collapse supernovae. To obtain the neutrino-driven explosions, we parameterize the neutrino fluxes emitted from the central protoneutron star and approximate the neutrino transfer by a light-bulb scheme. We find that the waveforms due to the anisotropic neutrino emissions show the monotonic increase with time, whose amplitudes are up to two order-of-magnitudes larger than the ones from the convective matter motions outside the protoneutron stars.   We point out that the amplitudes begin to become larger when the growth of the SASI enters the nonlinear phase, in which the deformation of the shocks and the neutrino anisotropy become large. From the spectrum analysis of the waveforms, we find that the amplitudes from the neutrinos are dominant over the ones from the matter motions at the frequency below ∼ 100 Hz, which are suggested to be within the detection limits of the detectors in the next generation such as LCGT and the advanced LIGO for a supernova at 10 kpc.   As a contribution to the gravitational wave background, we show that the amplitudes from this source could be larger at the frequency above ∼ 1 Hz than the primordial gravitational wave backgrounds, but unfortunately, invisible to the proposed space-based detectors. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0607/0607224v2.pdf"}
{"id": "astro-ph0607284", "abstract": "  We derive analytical formulae for the Minkowski Functions of the cosmic microwave background (CMB) and large-scale structure (LSS) from primordial non-Gaussianity. These formulae enable us to estimate a non-linear coupling parameter, f_NL, directly from the CMB and LSS data without relying on numerical simulations of non-Gaussian primordial fluctuations. One can use these formulae to estimate statistical errors on f_NL from Gaussian realizations, which are much faster to generate than non-Gaussian ones, fully taking into account the cosmic/sampling variance, beam smearing, survey mask, etc. We show that the CMB data from the Wilkinson Microwave Anisotropy Probe should be sensitive to |f_NL|≃40 at the 68", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0607/0607284v2.pdf"}
{"id": "astro-ph0607614", "abstract": "  We report on observations of four southern Anomalous X-ray Pulsars, (1RXS J170849.0-400910, 1E 1048.1-5937, 1E 1841-045 and AX J1845-0258), obtained at 1.4 GHz using the Parkes radio telescope. Radio pulsations from these sources have been searched (i) by directly folding the time series at a number of trial periods centered on the value of the spin rate obtained from the X-ray observations; (ii) by performing a blind search; (iii) using a code sensitive to single dedispersed pulses, in the aim to detect signals similar to those of the recently discovered Rotating RAdio Transients. No evidence for radio pulsations with an upper limit of  0.1 mJy for any of the four targets has been found. The blind search led to the serendipitous discovery of two new pulsars, rotating with a spin period of about 0.7 s and of 92 ms respectively, and to the further detection of 18 known pulsars, two of which were also detected in the single-pulse search. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0607/0607614v1.pdf"}
{"id": "astro-ph0607666", "abstract": "  Recent observations of pulsar wind nebulae and radio polarization profiles revealed a tendency of the alignment between the spin and velocity directions in neutron stars. We study the condition for spin-kick alignment using a toy model, in which the kick consists of many off-centered, randomly-oriented thrusts. Both analytical considerations and numerical simulations indicate that spin-kick alignment cannot be easily achieved if the proto-neutron star does not possess some initial angular momentum, contrary to some previous claims. To obtain the observed spin-kick misalignment angle distribution, the initial spin period of the neutron star must be smaller than the kick timescale. Typically, an initial period of a hundred milliseconds or less is required. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0607/0607666v3.pdf"}
{"id": "astro-ph0609019", "abstract": "  The large-scale dynamics of a two-fluid system with a time dependent interaction is studied analytically and numerically. We show how a rapid transition can significantly suppress the large-scale curvature perturbation and present approximative formulae for estimating the effect. By comparing to numerical results, we study the applicability of the approximation and find good agreement with exact calculations. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0609/0609019v2.pdf"}
{"id": "astro-ph0609272", "abstract": "  We present a short general overview of the main features of exotic models of neutron stars, focusing on the structural and dynamical predictions derived from them. In particular, we discuss the presence of “normal” quark matter and Color-Flavor Locked (CFL) states, including their possible self-bound versions, and mention some different proposals emerging from the study of QCD microphysics. A connection with actual observed data is the main goal to be addressed at this talk and along the meeting. It is demonstrated that exotic equations of state are not soft if the vacuum contributions are large enough, and argued that recent measurements of high pulsar masses (M ≥ 2 M_⊙) create problems for hadronic models in which hyperons should be present. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0609/0609272v1.pdf"}
{"id": "astro-ph0609394", "abstract": "  We present infrared spectroscopy of the recurrent nova RS Ophiuchi, obtained 11.81, 20.75 and 55.71 days following its 2006 eruption. The spectra are dominated by hydrogen recombination lines, together with HeI, OI and OII lines; the electron temperature of  10^4 K implied by the recombination spectrum suggests that we are seeing primarily the wind of the red giant, ionized by the ultraviolet flash when RS Oph erupted. However, strong coronal emission lines (i.e. emission from fine structure transitions in ions having high ionization potential) are present in the last spectrum. These imply a temperature of 930000K for the coronal gas; this is in line with x-ray observations of the 2006 eruption. The emission line widths decrease with time in a way that is consistent with the shock model for the x-ray emission. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0609/0609394v1.pdf"}
{"id": "astro-ph0609416", "abstract": "  Recent timing observations of the double pulsar J0737-3039A/B have shown that its transverse velocity is extremely low, only 10 km/s, and nearly in the Plane of the Galaxy. With this new information, we rigorously re-examine the history and formation of this system, determining estimates of the pre-supernova companion mass, supernova kick and misalignment angle between the pre- and post-supernova orbital planes. We find that the progenitor to the recently formed `B' pulsar was probably less than 2 MSun, lending credence to suggestions that this object may not have formed in a normal supernova involving the collapse of an iron core. At the same time, the supernova kick was likely non-zero. A comparison to the history of the double-neutron-star binary B1534+12 suggests a range of possible parameters for the progenitors of these systems, which should be taken into account in future binary population syntheses and in predictions of the rate and spatial distribution of short gamma-ray burst events. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0609/0609416v2.pdf"}
{"id": "astro-ph0609637", "abstract": "  This paper presents a novel method for determining the probability that a supernova candidate belongs to a known supernova type (such as Ia, Ibc, IIL, etc.), using its photometric information alone. It is validated with Monte Carlo, and both space- and ground- based data. We examine the application of the method to well-sampled as well as poorly sampled supernova light curves and investigate to what extent the best currently available supernova models can be used for typing supernova candidates. Central to the method is the assumption that a supernova candidate belongs to a group of objects that can be modeled; we therefore discuss possible ways of removing anomalous or less well understood events from the sample. This method is particularly advantageous for analyses where the purity of the supernova sample is of the essence, or for those where it is important to know the number of the supernova candidates of a certain type (e.g., in supernova rate studies). ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0609/0609637v2.pdf"}
{"id": "astro-ph0611167", "abstract": "  We observed mid-infrared (7.5-22 mum) spectra of AGB stars in the globular cluster 47 Tuc with the Spitzer telescope and find significant dust features of various types. Comparison of the characteristics of the dust spectra with the location of the stars in a logP-K-diagram shows that dust mineralogy and position on the AGB are related. A 13 mum feature is seen in spectra of low luminosity AGB stars. More luminous AGB stars show a broad feature at 11.5 mum. The spectra of the most luminous stars are dominated by the amorphous silicate bending vibration centered at 9.7 mum. For 47 Tuc AGB stars, we conclude that early on the AGB dust consisting primarily of Mg-, Al- and Fe oxides is formed. With further AGB evolution amorphous silicates become the dominant species. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0611/0611167v2.pdf"}
{"id": "astro-ph0611492", "abstract": "  The observational record of turbulence within the molecular gas phase of the interstellar medium is summarized. We briefly review the analysis methods used to recover the velocity structure function from spectroscopic imaging and the application of these tools on sets of cloud data. These studies identify a near-invariant velocity structure function that is independent of local the environment and star formation activity. Such universality accounts for the cloud-to-cloud scaling law between the global line-width and size of molecular clouds found by Larson (1981) and constrains the degree to which supersonic turbulence can regulate star formation. In addition, the evidence for large scale driving sources necessary to sustain supersonic flows is summarized. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0611/0611492v1.pdf"}
{"id": "astro-ph0612641", "abstract": "  Knowledge regarding the coronal magnetic field is important for the understanding of many phenomena, like flares and coronal mass ejections. Because of the low plasma beta in the solar corona the coronal magnetic field is often assumed to be force-free and we use photospheric vector magnetograph data to extrapolate the magnetic field into the corona with the help of a non-linear force-free optimization code. Unfortunately the measurements of the photospheric magnetic field contain inconsistencies and noise. In particular the transversal components (say Bx and By) of current vector magnetographs have their uncertainties. Furthermore the magnetic field in the photosphere is not necessary force-free and often not consistent with the assumption of a force-free field above. We develop a preprocessing procedure to drive the observed non force-free data towards suitable boundary conditions for a force-free extrapolation. As a result we get a data set which is as close as possible to the measured data and consistent with the force-free assumption. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0612/0612641v1.pdf"}
{"id": "astro-ph0703374", "abstract": "  We use a set of simulation-based models for the dissipationless evolution of galaxies since z=1 to constrain the fate of accreted satellites embedded in dark matter subhalos. These models assign stellar mass to dark matter halos at z=1 by relating the observed galaxy stellar mass function (GSMF) to the halo+subhalo mass function monotonically. The evolution of the stellar mass content is then followed using halo merger trees extracted from N-body simulations. Our models are differentiated only in the fate assigned to satellite galaxies once subhalos, within which satellites are embedded, disrupt. These models are confronted with the observed evolution in the massive end of the GSMF, the z 0 brightest cluster galaxy (BCG)-cluster mass relation, and the combined BCG and intracluster light (ICL) luminosity distribution – all observables expected to evolve approximately dissipationlessly since z=1. The combined observational constraints favor a model in which the vast majority (>80", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0703/0703374v1.pdf"}
{"id": "astro-ph9508023", "abstract": "  We calculate the contribution to the cosmic x-ray background (CXB) of a population of power law spectrum sources with spectral indices distributed over a broad range of values. The composite spectrum of this source population is significantly harder than that given by the power law having the average value of spectral indices. Starting from spectral distributions which are approximately those observed from quasars, it is possible to reproduce the CXB spectrum from  0.5 keV to  20 keV. If the spectra of quasars steepen at around 100 keV, the resulting composite spectrum nearly perfectly fits the CXB in the even broader energy range, up to  100 keV. The QSO population with broadly distributed spectral parameters is also characterized by a significant discrepancy between the results of hard and soft x-ray source counts. The same population of sources yields about three times more sources at 10 keV than at the corresponding flux at 1 keV, similarly to what is found from the comparison of HEAO A-1/Ginga and Einstein/ROSAT measurements. Thus, by allowing the spectra of QSO's to span a broad range of spectral indices, it is possible to reproduce both the CXB spectrum and account for the apparent differences in number counts in different energy bands. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9508/9508023v1.pdf"}
{"id": "astro-ph9510043", "abstract": "  Non-linear effects in the evolution of the axion field in the early Universe may lead to the formation of gravitationally bound clumps of axions, known as “miniclusters.” Minicluster masses and radii should be in the range M_ mc∼10^-12 M_⊙ and R_ mc∼ 10^10cm, and in plausible early-Universe scenarios a significant fraction of the mass density of the Universe may be in the form of axion miniclusters. If such axion miniclusters exist, they would have the physical properties required to be detected by “femtolensing.” ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9510/9510043v1.pdf"}
{"id": "astro-ph9706039", "abstract": "  Reverberation-mapping campaigns have revolutionized our understanding of AGN. They have allowed the direct determination of the broad-line region size, enabled mapping of the gas distribution around the central black hole, and are starting to resolve the continuum source structure. This review describes the recent and successful campaigns of the International AGN Watch consortium, outlines the theoretical background of reverberation mapping and the calculation of transfer functions, and addresses the fundamental difficulties of such experiments. It shows that such large-scale experiments have resulted in a “new BLR” which is considerably different from the one we knew just ten years ago. We discuss in some detail the more important new results, including the luminosity-size-mass relationship for AGN, and suggest ways to proceed in the near future. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9706/9706039v1.pdf"}
{"id": "astro-ph9707148", "abstract": "  The high energy experiment PDS is one of the Narrow Field Instruments aboard the X-ray astronomy satellite BeppoSAX. It covers the energy band from 15 to 300 keV. Here we report results on its in-flight performance and observations of galactic and extragalactic X-ray sources obtained during the Science Verification Phase of the satellite: in particular Crab, Cen X-3, 4U1626-67 and PKS2155-305. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9707/9707148v1.pdf"}
{"id": "astro-ph9710050", "abstract": "  The conditions for structure formation which ultimately lead to galaxies request further ingredients behind the simple collapse criteria. The Jean's criteria and the cooling criteria are those which are currently used. However in such a simple scheme, a fundamental problem occurs in hierarchical pictures, namely the OVERCOOLING: the predicted fraction of primordial gas expected to have cooled in the history of structure formation is for too large. The solution to this problem is likely to be a substantial re-heating phase. Here, we discussed one possible solution: the warm IGM picture. If the feedback of galaxy formation is able to heat the IGM up to temperatures of the order of 10^5-10^6 K, galaxy formation is inhibited on small mass scale. This leads to an inverse hierarchical picture: most of the large galaxies form at redshifts in the range 3 to 5, while small galaxies form at two different epoch: at an early phase at redshift greater than five and at a late phase, between redshift 3 and 0. Such a scheme may reproduce quite well the amount of HI gas versus redshift. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9710/9710050v1.pdf"}
{"id": "astro-ph9801234", "abstract": "  The next generation of cosmic microwave background (CMB) experiments, galaxy surveys, and high-redshift observations can potentially determine the nature of the dark matter observationally. With this in mind, we introduce a phenomenological model for a generalized dark matter (GDM) component and discuss its effect on large-scale structure and CMB anisotropies. Specifying the gravitational influence of the otherwise non-interacting GDM requires not merely a model for its equation of state but one for its full stress tensor.   From consideration of symmetries, conservation laws, and gauge invariance, we construct a simple but powerful 3 component parameterization of these stresses that exposes the new phenomena produced by GDM. Limiting cases include: a particle component (e.g. WIMPS, radiation or massive neutrinos), a cosmological constant, and a scalar field component. Intermediate cases illustrate how the clustering properties of the dark matter can be specified independently of its equation of state. This freedom allows one to alter the amplitude and features in the matter power spectrum relative to those of the CMB anisotropies while leaving the background cosmology fixed. Conversely, observational constraints on such properties can help determine the nature of the dark matter. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9801/9801234v2.pdf"}
{"id": "astro-ph9810260", "abstract": "  In order to understand what controls the star formation process in luminous starburst mergers (e.g., NGC 6240, Arp 220, and so on), we investigate observational properties of two samples of high-luminosity starburst galaxies mapped in CO(J=1–0) independently using both the Owens Valley Radio Observatory (Scoville et al. 1991) and the IRAM interferometer (Downes     Solomon 1998). We find that the surface density of far-infrared luminosity, Σ(FIR), is proportional linearly to the H_2 surface mass density, Σ(H_2), for the two samples; Σ(FIR) ∝Σ(H_2)^1.01±0.06 with a correlation coefficient of 0.96. It is often considered that Σ(FIR) provides a good measure of the star formation rate per unit area, Σ(SFR). It is also known that molecular gas is dominated in circumnuclear regions in the luminous starburst mergers; i.e., Σ(gas) ≃Σ(H_2). Therefore, the above relationship suggests a star formation law; Σ(SFR) ∝Σ(gas). We suggest that this star formation law favors the gravitational instability scenario rather than the cloud-cloud collision one. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9810/9810260v1.pdf"}
{"id": "astro-ph9811157", "abstract": "  We present the first X-ray detection of the Cartwheel's ring. The impact that created the characteristic optical structure is responsible also for an enhanced level of star formation to which we can ascribe the relatively high level of X-ray emission observed. Deeper images and spectroscopic information are needed to confirm or disprove the hypothesis that High Mass X-ray Binaries contribute most of the radiation in this band. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9811/9811157v1.pdf"}
{"id": "astro-ph9812188", "abstract": "  Imaging in the restframe ultraviolet has proven to be an effective and vital means of tracing dynamical patterns of star formation in galaxies out to high redshifts. Using images from the Ultraviolet Imaging Telescope (UIT), Hubble Space Telescope (HST) and complementary groundbased telescopes, we have investigated the starburst activity and associated dynamics in nearby early-type disk galaxies. Concentrating on the starburst-ring (R)SA(r)ab galaxy M94 (NGC 4736), we find compelling evidence for bar-mediated resonances as the primary drivers of evolution at the present epoch. Similar ring-bar dynamics may prevail in the centers of early-type disk galaxies at high redshift. The gravitationally-lensed \"Pretzel Galaxy\" (0024+1654) at a redshift of  1.5 provides an important precedent in this regard. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9812/9812188v1.pdf"}
{"id": "astro-ph9910212", "abstract": "  We report on the chemical abundances of stars in the Carina dwarf spheroidal galaxy (dSph) derived from low-resolution spectra. We have determined values of [Fe/H] for 52 stars from the reduced equivalent width of the Ca II infrared triplet lines. The Carina dSph has a mean metallicity of [Fe/H] = -1.99 +/- 0.08 and an intrinsic metallicity dispersion 0.25 dex (1 sigma). By directly determining the chemical abundances of Carina stars through spectroscopy, we can overcome the age-metallicity degeneracy inherent in color-magnitude diagrams (CMDs) and determine its star-formation history with unprecedented accuracy. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9910/9910212v1.pdf"}
{"id": "astro-ph9912157", "abstract": "  We present a new modeling tool for planetary nebulae, based on 3D photoionization calculations. Our goal is to show that all the information provided by observations, regarding kinematics and morphology, have to be consistently accounted for, in order to get a real insight of the object. Only 3D simulations offer this possibility. From models for two theoretical PNe, we show that the enhancement in the equatorial zone observed in several PNe is not necessarily due to a density gradient, as usually interpreted. It is also shown that asymmetric velocity profiles often observed (e.g., Gesicki et al. 1998) can be easily reproduced. Observations providing a better insight on the morphology of the PN are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9912/9912157v1.pdf"}
{"id": "chao-dyn9909026", "abstract": "  We study the properties of the two-point spectral form factor for classically chaotic systems with spin 1/2 in the semiclassical limit, with a suitable semiclassical trace formula as our principal tool. To this end we introduce a regularized form factor and discuss the limit in which the so-called diagonal approximation can be recovered. The incorporation of the spin contribution to the trace formula requires an appropriate variant of the equidistribution principle of long periodic orbits as well as the notion of a skew product of the classical translational and spin dynamics. Provided this skew product is mixing, we show that generically the diagonal approximation of the form factor coincides with the respective predictions from random matrix theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/chao-dyn/pdf/9909/9909026v1.pdf"}
{"id": "cond-mat0004021", "abstract": "  The model under consideration is a two-dimensional two-component plasma, stable against collapse for the dimensionless coupling constant β<2. The combination of a technique of renormalized Mayer expansion with the mapping onto the sine-Gordon theory provides the full thermodynamics of the plasma in the whole stability range of β. The explicit forms of the density-fugacity relationship and of the specific heat (at constant volume) per particle are presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0004/0004021v1.pdf"}
{"id": "cond-mat0005472", "abstract": "  We study the asymptotic behaviour of resistance scaling and fluctuation of resistance that give rise to flicker noise in an n-simplex lattice. We propose a simple method to calculate the resistance scaling and give a closed-form formula to calculate the exponent, β_L, associated with resistance scaling, for any n. Using current cumulant method we calculate the exact noise exponent for n-simplex lattices. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0005/0005472v1.pdf"}
{"id": "cond-mat0006144", "abstract": "  Using longer spectra we re-analyze spectral properties of the two-body random ensemble studied thirty years ago. At the center of the spectra the old results are largely confirmed, and we show that the non-ergodicity is essentially due to the variance of the lowest moments of the spectra. The longer spectra allow to test and reach the limits of validity of French's correction for the number variance. At the edge of the spectra we discuss the problems of unfolding in more detail. With a Gaussian unfolding of each spectrum the nearest neighbour spacing distribution between ground state and first exited state is shown to be stable. Using such an unfolding the distribution tends toward a semi-Poisson distribution for longer spectra. For comparison with the nuclear table ensemble we could use such unfolding obtaining similar results as in the early papers, but an ensemble with realistic splitting gives reasonable results if we just normalize the spacings in accordance with the procedure used for the data. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0006/0006144v1.pdf"}
{"id": "cond-mat0009185", "abstract": "  We discuss the dynamics of ultracold atoms in an optical potential accelerated by gravity. The positions and widths of the Wannier-Stark ladder of resonances are obtained as metastable states. The metastable Wannier-Bloch states oscillate in a single band with the Bloch period. The width of the resonance gives the rate transition to the continuum. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0009/0009185v1.pdf"}
{"id": "cond-mat0009445", "abstract": "  The charge fluctuations of two nearby mesoscopic conductors coupled only via the long range Coulomb force are discussed and used to find the dephasing rate which one conductor exerts on the other. The discussion is based on a formulation of the scattering approach for charge densities and the density response to a fluctuating potential. Coupling to the Poisson equation results in an electrically self-consistent description of charge fluctuations. At equilibrium the low-frequency noise power can be expressed with the help of a charge relaxation resistance (which together with the capacitance determines the RC-time of the structure). In the presence of transport the low frequency charge noise power is determined by a resistance which reflects the presence of shot noise. We use these results to derive expressions for the dephasing rates of Coulomb coupled conductors and to find a self-consistent expression for the measurement time. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0009/0009445v1.pdf"}
{"id": "cond-mat0010216", "abstract": "  We use molecular dynamics simulations in two dimensions to investigate the possibility that a core-softened potential can reproduce static and dynamic anomalies found experimentally in liquid water: (i) the increase in specific volume upon cooling, (ii) the increase in isothermal compressibility upon cooling, and (iii) the increase in the diffusion coefficient with pressure. We relate these anomalies to the shape of the potential. We obtain the phase diagram of the system and identify two solid phases: a square crystal (high density phase), and a triangular crystal (low density phase). We also discuss the relation between the anomalies observed and the polymorphism of the solid. Finally, we compare the phase diagram of our model system with experimental data, noting especially the line of temperatures of maximum density, line of pressures of maximum diffusion constant, and line of temperatures of minimum isothermal compressibility. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0010/0010216v1.pdf"}
{"id": "cond-mat0011330", "abstract": "  Closed analytical expressions for scattering intensity and other global structure factors are derived for a new solvable model of polydisperse sticky hard spheres. The starting point is the exact solution of the “mean spherical approximation” for hard core plus Yukawa potentials, in the limit of infinite amplitude and vanishing range of the attractive tail, with their product remaining constant. The choice of factorizable coupling (stickiness) parameters in the Yukawa term yields a simpler “dyadic structure” in the Fourier transform of the Baxter factor correlation function q_ij(r), with a remarkable simplification in all structure functions with respect to previous works. The effect of size and stickiness polydispersity is analyzed and numerical results are presented for two particular versions of the model: i) when all polydisperse particles have a single, size-independent, stickiness parameter, and ii) when the stickiness parameters are proportional to the diameters. The existence of two different regimes for the average structure factor, respectively above and below a generalized Boyle temperature which depends on size polydispersity, is recognized and discussed. Because of its analycity and simplicity, the model may be useful in the interpretation of small-angle scattering experimental data for polydisperse colloidal fluids of neutral particles with surface adhesion. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0011/0011330v1.pdf"}
{"id": "cond-mat0102113", "abstract": "  We revisit the mean field model of globally and harmonically coupled parametric oscillators subject to periodic block pulses with initially random phases. The phase diagram of regions of collective parametric instability is presented, as is a detailed characterization of the motions underlying these instabilities. This presentation includes regimes not identified in earlier work [I. Bena and C. Van den Broeck, Europhys. Lett. 48, 498 (1999)]. In addition to the familiar parametric instability of individual oscillators, two kinds of collective instabilities are identified. In one the mean amplitude diverges monotonically while in the other the divergence is oscillatory. The frequencies of collective oscillatory instabilities in general bear no simple relation to the eigenfrequencies of the individual oscillators nor to the frequency of the external modulation. Numerical simulations show that systems with only nearest neighbor coupling have collective instabilities similar to those of the mean field model. Many of the mean field results are already apparent in a simple dimer [M. Copelli and K. Lindenberg, to appear in Phys. Rev. E]. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0102/0102113v1.pdf"}
{"id": "cond-mat0102200", "abstract": "  We propose a new approach to implement the density matrix renormalization group (DMRG) in two dimensions. With this approach the initial blocks of a L by L lattice are built up directly from the matrix elements of a (L-1) by L-1) lattice and the topological characteristics of two dimensional lattices is preserved in the iteration of DMRG. By applying it to the spin-1/2 Heisenberg model on both square and triangle lattices, we find that this approach is significantly more efficient and accurate than other two-dimensional DMRG methods currently in use. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0102/0102200v3.pdf"}
{"id": "cond-mat0106238", "abstract": "  We derive a formula for the quantum corrections to the electrical current for a metal out of equilibrium. In the limit of linear current-voltage characteristics our formula reproduces the well known Altshuler-Aronov correction to the conductivity of a disordered metal. The current formula is obtained by a direct diagrammatic approach, and is shown to agree with what is obtained within the Keldysh formulation of the non-linear sigma model. As an application we calculate the current of a mesoscopic wire. We find a current-voltage characteristics that scales with eV/kT, and calculate the different scaling curves for a wire in the hot-electron regime and in the regime of full non-equilibrium. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0106/0106238v1.pdf"}
{"id": "cond-mat0202458", "abstract": "  We have investigated the effect of particle shape on the eletrorotation (ER) spectrum of living cells suspensions. In particular, we consider coated oblate spheroidal particles and present a theoretical study of ER based on the spectral representation theory. Analytic expressions for the characteristic frequency as well as the dispersion strength can be obtained, thus simplifying the fitting of experimental data on oblate spheroidal cells that abound in the literature. From the theoretical analysis, we find that the cell shape, coating as well as material parameters can change the ER spectrum. We demonstrate good agreement between our theoretical predictions and experimental data on human erthrocytes suspensions. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0202/0202458v1.pdf"}
{"id": "cond-mat0203206", "abstract": "  In this paper we study the effect of external harmonic forcing on a one-dimensional oscillatory system described by the complex Ginzburg-Landau equation (CGLE). For a sufficiently large forcing amplitude, a homogeneous state with no spatial structure is observed. The state becomes unstable to a spatially periodic “stripe” state via a supercritical bifurcation as the forcing amplitude decreases. An approximate phase equation is derived, and an analytic solution for the stripe state is obtained, through which the asymmetric behavior of the stability border of the state is explained. The phase equation, in particular the analytic solution, is found to be very useful in understanding the stability borders of the homogeneous and stripe states of the forced CGLE. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0203/0203206v1.pdf"}
{"id": "cond-mat0206051", "abstract": "  The effect of high pressures to 40 GPa on the crystal structure and lattice dynamics of AlB2 was studied by synchrotron x-ray powder diffraction, Raman spectroscopy, and first-principles calculations. There are no indications for a pressure-induced structural phase transition. The Raman spectra of the metallic sample exhibit a well-defined peak near 980 cm^-1 at 0 GPa which can be attributed to the Raman-active E_2g zone-center phonon. Al deficiency of  11", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0206/0206051v1.pdf"}
{"id": "cond-mat0206577", "abstract": "  Financial correlation matrices measure the unsystematic correlations between stocks. Such information is important for risk management. The correlation matrices are known to be “noise dressed”. We develop a new and alternative method to estimate this noise. To this end, we simulate certain time series and random matrices which can model financial correlations. With our approach, different correlation structures buried under this noise can be detected. Moreover, we introduce a measure for the relation between noise and correlations. Our method is based on a power mapping which efficiently suppresses the noise. Neither further data processing nor additional input is needed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0206/0206577v1.pdf"}
{"id": "cond-mat0207109", "abstract": "  We study the role of dissipation and structural defects on the time evolution of quantum dot arrays with mobile charges under external driving fields. These structures, proposed as quantum dot cellular automata, exhibit interesting quantum dynamics which we describe in terms of equations of motion for the density matrix. Using an open system approach, we study the role of asymmetries and the microscopic electron-phonon interaction on the general dynamical behavior of the charge distribution (polarization) of such systems. We find that the system response to the driving field is improved at low temperatures (and/or weak phonon coupling), before deteriorating as temperature and asymmetry increase. In addition to the study of the time evolution of polarization, we explore the linear entropy of the system in order to gain further insights into the competition between coherent evolution and dissipative processes. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0207/0207109v1.pdf"}
{"id": "cond-mat0301261", "abstract": "  We present a new method to derive kinetic equations for systems undergoing non-linear transport in the presence of memory effects. In the framework of mesoscopic nonequilibrium thermodynamics, we derive a generalized Fokker-Planck equation incorporating memory effects through time-dependent coefficients. As applications, we first discuss the non-Markovian dynamics of anomalous diffusion in a potential, analyzing the validity of the fluctuation-dissipation theorem. In a second application, we propose a new ratchet mechanism in which the periodic driving acting on the particle is induced by the Onsager coupling of the diffusion current with an oscillating thermodynamic force. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0301/0301261v1.pdf"}
{"id": "cond-mat0301555", "abstract": "  We study the performance of Weibull and scale free Internet-like networks and compare them to a classical random graph based network. The scaling of the traffic load with the nodal degree is established, and confimed in a numerical simulation of the TCP traffic. The scaling allows us to estimate the link capacity upgrade required making and extra connection to an existing node. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0301/0301555v2.pdf"}
{"id": "cond-mat0302298", "abstract": "  Dynamical properties of a Lennard-Jones binary mixture embedded in an off lattice matrix of soft spheres are studied in the direct space upon supercooling by molecular dynamics simulations. On lowering temperature the smaller particles tend to avoid the soft sphere interfaces and correspondingly their mobility decreases below the one of the larger particles. The system displays a dynamic behaviour consistent with the Mode Coupling predictions. A decrease of the mode coupling crossover temperature with respect to the bulk is found. We find however that the range of validity of the theory shrinks with respect to the bulk. This is due to the change in the smaller particle mobility and to a substantial enhancement of hopping processes well above the cross over temperature upon confinement. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0302/0302298v1.pdf"}
{"id": "cond-mat0305552", "abstract": "  We examine the energetics of bulk and layer-roton excitations of 4He in various porous medial such as aerogel, Geltech, or Vycor, in order to find out what conclusions can be drawn from experiments on the energetics about the physisorption mechanism. The energy of the layer-roton minimum depends sensitively on the substrate strength, thus providing a mechanism for a direct measurement of this quantity. On the other hand, bulk-like roton excitations are largely independent of the interaction between the medium and the helium atoms, but the dependence of their energy on the degree of filling reflects the internal structure of the matrix and can reveal features of 4He at negative pressures. While bulk-like rotons are very similar to their true bulk counterparts, the layer modes are not in close relation to two-dimensional rotons and should be regarded as a third, completely independent kind of excitation. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0305/0305552v1.pdf"}
{"id": "cond-mat0306260", "abstract": "  An electromagnetic (EM) Bloch wave propagating in a photonic crystal (PC) is characterized by the immittance (impedance and admittance) of the wave. The immittance is used to investigate transmission and reflection at a surface or an interface of the PC. In particular, the general properties of immittance are useful for clarifying the wave propagation characteristics. We give a general proof that the immittance of EM Bloch waves on a plane in infinite one- and two-dimensional (2D) PCs is real when the plane is a reflection plane of the PC and the Bloch wavevector is perpendicular to the plane. We also show that the pure-real feature of immittance on a reflection plane for an infinite three-dimensional PC is good approximation based on the numerical calculations. The analytical proof indicates that the method used for immittance matching is extremely simplified since only the real part of the immittance function is needed for analysis without numerical verification. As an application of the proof, we describe a method based on immittance matching for qualitatively evaluating the reflection at the surface of a semi-infinite 2D PC, at the interface between a semi-infinite slab waveguide (WG) and a semi-infinite 2D PC line-defect WG, and at the interface between a semi-infinite channel WG and a semi-infinite 2D PC slab line-defect WG. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0306/0306260v2.pdf"}
{"id": "cond-mat0306706", "abstract": "  We calculate the current-phase relation of a long Josephson junction consisting of two ferromagnetic domains with equal, but opposite magnetization h, sandwiched between two superconductors. In the clean limit, the current-phase relation is obtained with the help of Eilenberger equation. In general, the supercurrent oscillations are non-sinusoidal and their amplitude decays algebraically when the exchange field is increased. If the two domains have the same size, the amplitude is independent of h, due to an exact cancellation of the phases acquired in each ferromagnetic domain. These results change drastically in the presence of disorder. We explicitly study two cases: Fluctuations of the domain size (in the framework of the Eilenberger equation) and impurity scattering (using the Usadel equation). In both cases, the current-phase relation becomes sinusoidal and the amplitude of the supercurrent oscillations is exponentially suppressed with h, even if the domains are identical on average. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0306/0306706v1.pdf"}
{"id": "cond-mat0309515", "abstract": "  We investigate the evolution of a single unbounded interface between ordered phases in two-dimensional Ising ferromagnets that are endowed with single-spin-flip zero-temperature Glauber dynamics. We examine specifically the cases where the interface initially has either one or two corners. In both examples, the interface evolves to a limiting self-similar form. We apply the continuum time-dependent Ginzburg-Landau equation and a microscopic approach to calculate the interface shape. For the single corner system, we also discuss a correspondence between the interface and the Young tableau that represents the partition of the integers. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0309/0309515v3.pdf"}
{"id": "cond-mat0403098", "abstract": "  We present a theoretical study of the energy levels in a parabolically confined quantum dot in the presence of the Rashba spin-orbit interaction (SOI). The features of some low-lying states in various strengths of the SOI are examined at finite magnetic fields. The presence of a magnetic field enhances the possibility of the spin polarization and the SOI leads to different energy dependence on magnetic fields applied. Furthermore, in high magnetic fields, the spectra of low-lying states show basic features of Fock-Darwin levels as well as Landau levels. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0403/0403098v2.pdf"}
{"id": "cond-mat0404163", "abstract": "  We use the local density approximation (LDA) and LDA+U schemes to study the magnetism of (GaMn)As and (GaMn)N for a number of Mn concentrations and varying number of holes. We show that for both systems and both calculational schemes the presence of holes is crucial for establishing ferromagnetism. For both systems, the introduction of U increases delocalization of the holes and, simultaneously, decreases the p-d interaction. Since these two trends exert opposite influences on the Mn-Mn exchange interaction the character of the variation of the Curie temperature (T_C) cannot be predicted without direct calculation. We show that the variation of T_C is different for two systems. For low Mn concentrations we obtain the tendency to increasing T_C in the case of (GaMn)N whereas an opposite tendency to decreasing T_C is obtained for (GaMn)As. We reveal the origin of this difference by inspecting the properties of the densities of states and holes for both systems. The main body of calculations is performed within a supercell approach. The Curie temperatures calculated within the coherent potential approximation to atomic disorder are reported for comparison. Both approaches give similar qualitative behavior. The results of calculations are related to the experimental data. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0404/0404163v1.pdf"}
{"id": "cond-mat0404237", "abstract": "  Finite element methods are used to study non-adhesive, frictionless contact between elastic solids with self-affine surfaces. We find that the total contact area rises linearly with load at small loads. The mean pressure in the contact regions is independent of load and proportional to the rms slope of the surface. The constant of proportionality is nearly independent of Poisson ratio and roughness exponent and lies between previous analytic predictions. The contact morphology is also analyzed. Connected contact regions have a fractal area and perimeter. The probability of finding a cluster of area a_c drops as a_c^-τ where τ increases with decreasing roughness exponent. The distribution of pressures shows an exponential tail that is also found in many jammed systems. These results are contrasted to simpler models and experiment. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0404/0404237v2.pdf"}
{"id": "cond-mat0407289", "abstract": "  The thermal fluctuations that exist at very low temperature in disordered systems are often attributed to the existence of some two-level excitations. In this paper, we revisit this question via the explicit studies of the following 1D models (i) a particle in 1D random potentials (ii) the random field Ising chain with continuous disorder distribution. In both cases, we define precisely the `two-level' excitations and their statistical properties, and we show that their contributions to various observables are in full agreement at low temperature with the the rigorous results obtained independently. The statistical properties of these two-level excitations moreover yield simple identities at order T in temperature for some generating functions of thermal cumulants. For the random-field Ising chain, in the regime where the Imry-Ma length is large, we obtain that the specific heat is dominated by small non-universal excitations, that depend on the details of the disorder distribution, whereas the magnetic susceptibility and the Edwards-Anderson order parameter are dominated by universal large excitations, whose statistical properties only depend on the variance of the initial disorder via the Imry-Ma length. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0407/0407289v1.pdf"}
{"id": "cond-mat0407311", "abstract": "  The family name distribution in Korea is investigated in comparison with previous studies in other countries. In Korea, both the family name and its birthplace, where the ancestor of the family originated, are commonly used to distinguish one family name from the others. The family name distributions with and without the information of the regional origins are analyzed by using different data sets of various sizes, and compared with previous studies performed in other countries. The growth rate of the family is empirically obtained. Contrary to commonly used assumptions, the growth rate is found to be higher for the smaller family. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0407/0407311v1.pdf"}
{"id": "cond-mat0408103", "abstract": "  The definition of the fundamental quantity, the chemical potential, is badly confused in the literature: there are at least three distinct definitions in various books and papers. While they all give the same result in the thermodynamic limit, major differences between them can occur for finite systems, in anomalous cases even for finite systems as large as a cm^3. We resolve the situation by arguing that the chemical potential defined as the symbol μ conventionally appearing in the grand canonical density operator is the uniquely correct definition valid for all finite systems, the grand canonical ensemble being the only one of the various ensembles usually discussed (microcanonical, canonical, Gibbs, grand canonical) that is appropriate for statistical thermodynamics, whenever the chemical potential is physically relevant. The zero-temperature limit of this μ was derived by Perdew et al. for finite systems involving electrons, generally allowing for electron-electron interactions; we extend this derivation and, for semiconductors, we also consider the zero-T limit taken after the thermodynamic limit. The enormous finite size corrections (in macroscopic samples, e.g. 1 cm^3) for one rather common definition of the c.p., found recently by Shegelski within the standard effective mass model of an ideal intrinsic semiconductor, are discussed. Also, two very-small-system examples are given, including a quantum dot. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0408/0408103v2.pdf"}
{"id": "cond-mat0408400", "abstract": "  We solve for the electronic Raman scattering response functions on an infinite-dimensional hypercubic lattice employing dynamical mean field theory. This contribution extends previous work on the nonresonant response to include the mixed and resonant contributions. We focus our attention on the spinless Falicov-Kimball model, where the problem can be solved exactly, and the system can be tuned to go through a Mott-Hubbard-like metal-insulator transition. Resonant effects vary in different scattering geometries, corresponding to the symmetries of the charge excitations scattered by the light. We do find that the Raman response is large near the double resonance, where the transfered frequency is close to the incident photon frequency. We also find a joint resonance of both the charge-transfer peak and the low-energy peak when the incident photon frequency is on the order of the interaction strength. In general, the resonance effects can create order of magnitude (or more) enhancements of features in the nonresonant response, especially when the incident photon frequency is somewhat larger than the frequency of the nonresonant feature. Finally, we find that the resonant effects also exhibit isosbestic behavior, even in the A1g and B2g sectors, and it is most prominent when the incident photon frequency is on the order of the interaction energy. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0408/0408400v1.pdf"}
{"id": "cond-mat0409318", "abstract": "  The electronic, structural and vibrational properties of small carbon interstitial and antisite clusters are investigated by ab initio methods in 3C and 4H-SiC. The defects possess sizable dissociation energies and may be formed via condensation of carbon interstitials, e.g. generated in the course of ion implantation. All considered defect complexes possess localized vibrational modes (LVM's) well above the SiC bulk phonon spectrum. In particular, the compact antisite clusters exhibit high-frequency LVM's up to 250meV. The isotope shifts resulting from a_13C enrichment are analyzed. In the light of these results, the photoluminescence centers D_II and P-U are discussed. The dicarbon antisite is identified as a plausible key ingredient of the D_II-center, whereas the carbon split-interstitial is a likely origin of the P-T centers. The comparison of the calculated and observed high-frequency modes suggests that the U-center is also a carbon-antisite based defect. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0409/0409318v1.pdf"}
{"id": "cond-mat0410412", "abstract": "  This paper presents a thorough evaluation of a bistable system versus a matched filter in detecting bipolar pulse signals. The detectability of the bistable system can be optimized by adding noise, i.e. the stochastic resonance (SR) phenomenon. This SR effect is also demonstrated by approximate statistical detection theory of the bistable system and corresponding numerical simulations. Furthermore, the performance comparison results between the bistable system and the matched filter show that (a) the bistable system is more robust than the matched filter in detecting signals with disturbed pulse rates, and (b) the bistable system approaches the performance of the matched filter in detecting unknown arrival times of received signals, with an especially better computational efficiency. These significant results verify the potential applicability of the bistable system in signal detection field. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0410/0410412v1.pdf"}
{"id": "cond-mat0412588", "abstract": "  We study the dynamic behaviour of a quantum two-level system with periodically varying parameters by solving the master equation for the density matrix. Two limiting cases are considered: multiphoton Rabi oscillations and Landau-Zener transitions. The approach is applied to the description of the dynamics of superconducting qubits. In particular, the case of the interferometer-type charge qubit with periodically varying parameters (gate voltage or magnetic flux) is investigated. The time-averaged energy level populations are calculated as funtions of the qubit's control parameters. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0412/0412588v1.pdf"}
{"id": "cond-mat0502596", "abstract": "  In higher Landau levels (N>1), the ground state of the two-dimensional electron gas in a strong perpendicular magnetic field evolves from a Wigner crystal for small filling ν of the partially filled Landau level, into a succession of bubble states with increasing number of guiding centers per bubble as ν increases, to a modulated stripe state near ν =0.5. In this work, we compute the frequency-dependent longitudinal conductivity ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0502/0502596v1.pdf"}
{"id": "cond-mat0503197", "abstract": "  We investigate the interaction effect between oxygen impurities in crystalline germanium on the basis of a quantum rotor model. The dipolar interaction of nearby oxygen impurities engenders non-trivial low-lying excitations, giving rise to anomalous behaviors for oxygen-doped germanium (Ge:O) below a few degrees Kelvin. In particular, it is theoretically predicted that Ge:O samples with oxygen-concentration of 10^17-18cm^-3 show (i) power-law specific heats below 0.1 K, and (ii) a peculiar hump in dielectric susceptibilities around 1 K. We present an interpretation for the power-law specific heats, which is based on the picture of local double-well potentials randomly distributed in Ge:O samples. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0503/0503197v1.pdf"}
{"id": "cond-mat0503318", "abstract": "  We investigate effects of strong electron correlation on magnetoelectric transport phenomena in noncentrosymmetric superconductors with particular emphasis on its application to the recently discovered heavy-fermion superconductor CePt_3Si. Taking into account electron correlation effects in a formally exact way, we obtain the expression of the magnetoelectric coefficient for the Zeeman-field-induced paramagnetic supercurrent, of which the existence was predicted more than a decade ago. It is found that in contrast to the usual Meissner current, which is much reduced by the mass renormalization factor in the heavy-fermion state, the paramagnetic supercurrent is not affected by the Fermi liquid effect. This result implies that the experimental observation of the magnetoelectric effect is more feasible in heavy-fermion systems than that in conventional metals with moderate effective mass. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0503/0503318v2.pdf"}
{"id": "cond-mat0506778", "abstract": "  We study dynamical heterogeneity and glassy dynamics in a kinetically constrained lattice gas model which has both translational and rotational degrees of freedom. We find that the rotational diffusion constant tracks the structural relaxation time as density is increased whereas the translational diffusion constant exhibits a strong decoupling. We investigate distributions of exchange and persistence times for both the rotational and translational degrees of freedom and compare our results on the distributions of rotational exchange times to recent single molecule studies. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0506/0506778v1.pdf"}
{"id": "cond-mat0508562", "abstract": "  It has been demonstrated experimentally that non-axially symmetric vortices precess around the centre of a Bose-Einstein condensate. Two types of single vortex states have been observed, usually referred to as the S-vortex and the U-vortex. We study theoretically the single vortex excitations in spherical and elongated condensates as a function of the interaction strength. We solve numerically the Gross-Pitaevskii equation and calculate the angular momentum as a function of precession frequency. The existence of two types of vortices means that we have two different precession frequencies for each angular momentum value. As the interaction strength increases the vortex lines bend and the precession frequencies shift to lower values. We establish that for given angular momentum the S-vortex has higher energy than the U-vortex in a rotating elongated condensate. We show that the S-vortex is related to the solitonic vortex which is a nonlinear excitation in the nonrotating system. For small interaction strengths the S-vortex is related to the dark soliton. In the dilute limit a lowest Landau level calculation provides an analytic description of these vortex modes in terms of the harmonic oscillator states. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0508/0508562v1.pdf"}
{"id": "cond-mat0508637", "abstract": "  A systematic study of both classical and quantum geometric frustrated Ising models with a competing ordering mechanism is reported in this paper. The ordering comes in the classical case from a coupling of 2D layers and in the quantum model from the quantum dynamics induced by a transverse field. By mapping the Ising models on a triangular lattice to elastic lattices of non-crossing strings, we derive an exact relation between the spin variables and the displacement field of the strings. Using this map both for the classical (2+1)D stacked model and the quantum frustrated 2D system, we obtain a microscopic derivation of an effective Hamiltonian which was proposed before on phenomenological grounds within a Landau-Ginzburg-Wilson approach. In contrast to the latter approach, our derivation provides the coupling constants and hence the entire transverse field–versus–temperature phase diagram can be deduced, including the universality classes of both the quantum and the finite–temperature transitions. The structure of the ordered phase is obtained from a detailed entropy argument. We compare our predictions to recent simulations of the quantum system and find good agreement. We also analyze the connections to a dimer model on the hexagonal lattice and its height profile representation, providing a simple derivation of the continuum free energy and a physical explanation for the universality of the stiffness of the height profile for anisotropic couplings. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0508/0508637v1.pdf"}
{"id": "cond-mat0511370", "abstract": "  We have studied the dissipative dynamics of a solid-state qubit with an extra electron confined to either one of two coupled quantum dots. Previous theoretical work based on Bloch-type rate equations gave an unphysical uniform occupation probability of the electron in the quantum dots even for non-identical dots. We show that this is due to neglecting higher order interactions in the analysis. By including higher order terms, we obtain expected asymmetric occupation probabilities for non-identical dots. Our work demonstrates that the high order interaction terms can lead to important qualitative impacts on the operation of the qubit. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0511/0511370v2.pdf"}
{"id": "cond-mat0512437", "abstract": "  The steady current induced by electromagnetic field in a 2D system with asymmetric scatterers is studied. The scatterers are assumed to be oriented cuts with one diffusive and another specular sides. Besides, the existence of isotropic impurity scatterers is assumed. This simple model simulates the lattice of half-disk which have been studied numerically recently. The model allows the exact solution in the framework of the kinetic equation. The static current response in the second order of electric field is obtained. The photogalvanic tensor contains both responses to linear and circular polarization of electromagnetic field. The model possesses non-analyticity with regards to the rate of impurity scattering. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0512/0512437v1.pdf"}
{"id": "cond-mat0512540", "abstract": "  We calculate Curie temperatures and study the stability of ferromagnetism in diluted magnetic materials, taking as a model for the exchange between magnetic impurities a damped Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction and a shor t range term representing the effects of superexchange. To properly include effects of spin and thermal fluctuations as well as geometric disorder, we solve the effective Heisenberg Hamiltonian by means of a recently developed semi-analytical approach. This approach, “self-consistent local Random Phase Approximation (SC-L RPA)”, is explained. We show that previous mean-field treatments, which have been widely used in the literature, largely overestimate both the Curie temperatures and the stability of ferromagnetism as a function of carrier density. The discr epancy when compared to the current approach was that effects of frustration in RKKY oscillations had been strongly underestimated by such simple mea n-field theories. We argue that the use, as is frequent, of a weakly-disordered RKKY exchange to model ferromagnetism in diluted III-V systems is inconsistent with the observation of ferromagnetism over a wide region of itinerant carrier densities. This may be puzzling when compared to the apparent success of calculations based on ab-initio estimates of the coupling; we propose a resolution to this issue by taking RKKY-like interactions between resonant states close to the Fermi level. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0512/0512540v1.pdf"}
{"id": "cond-mat0603818", "abstract": "  The statistical theory of certain complex wave interference phenomena, like the statistical fluctuations of transmission and reflection of waves, is of considerable interest in many fields of physics. In this article we shall be mainly interested in those situations where the complexity derives from the quenched randomness of scattering potentials, as in the case of disordered conductors, or, more in general, disordered waveguides. In studies performed in such systems one has found remarkable statistical regularities, in the sense that the probability distribution for various macroscopic quantities involves a rather small number of relevant physical parameters, while the rest of the microscopic details serves as mere \"scaffolding\". We shall review past work in which this feature was captured following a maximum-entropy approach, as well as later studies in which the existence of a limiting distribution, in the sense of a generalized central-limit theorem, has been actually demonstrated. We then describe a microscopic potential model that was developed recently, which gives rise to a further generalization of the central-limit theorem and thus to a limiting macroscopic statistics. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0603/0603818v1.pdf"}
{"id": "cond-mat0604386", "abstract": "  We obtain the phase diagram of the half-filled two-dimensional Hubbard model on a square lattice in the presence of Einstein phonons. We find that the interplay between the instantaneous electron-electron repulsion and electron-phonon interaction leads to new phases. In particular, a d_x^2-y^2-wave superconducting phase emerges when both anisotropic phonons and repulsive Hubbard interaction are present. For large electron-phonon couplings, charge-density-wave and s-wave superconducting regions also appear in the phase diagram, and the widths of these regions are strongly dependent on the phonon frequency, indicating that retardation effects play an important role. Since at half-filling the Fermi surface is nested, spin-density-wave is recovered when the repulsive interaction dominates. We employ a functional multiscale renormalization-group method that includes both electron-electron and electron-phonon interactions, and take retardation effects fully into account. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0604/0604386v2.pdf"}
{"id": "cond-mat0605081", "abstract": "  We theoretically investigate cross-talk in hyperfine gate control of donor-qubit quantum computer architectures, in particular the Kane proposal. By numerically solving the Poisson and Schrödinger equations for the gated donor system, we calculate the change in hyperfine coupling and thus the error in spin-rotation for the donor nuclear-electron spin system, as the gate-donor distance is varied. We thus determine the effect of cross-talk - the inadvertent effect on non-target neighbouring qubits - which occurs due to closeness of the control gates (20-30nm). The use of compensation protocols is investigated, whereby the extent of crosstalk is limited by the application of compensation bias to a series of gates. In light of these factors the architectural implications are then considered. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0605/0605081v1.pdf"}
{"id": "cond-mat0606262", "abstract": "  We propose a general procedure for reducing the three-dimensional Schrodinger equation for atoms moving along a strongly confining atomic waveguide to an effective one-dimensional equation. This procedure is applied to the case of a rotating closed-loop waveguide. The possibility of including mean-field atomic interactions is presented. Application of the general theory to characterize a new concept of atomic waveguide based on optical tweezers is finally discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0606/0606262v1.pdf"}
{"id": "cond-mat0607471", "abstract": "  We discuss the influence of electrical effects on spin transport, and in particular the propagation and relaxation of spin polarized electrons in the presence of inhomogeneous electric fields. We show that the spin relaxation length strongly depends on electric field gradients, and that significant suppression of electron spin polarization can occur as a result thereof. A discussion in terms of a drift-diffusion picture, and self-consistent numerical calculations based on a Boltzmann-Poisson approach shows that the spin relaxation length in fact can be of the order of the charge screening length. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0607/0607471v1.pdf"}
{"id": "cond-mat0607759", "abstract": "  We investigate the tunability of electrostatic coupling between solid state quantum dots as building blocks for quantum bits. Specifically, our analysis is based upon two-dimensional electron systems (2DEG) and depletion by top gates. We are interested in whether the Coulomb interaction between qubits can be tuned by electrical means using screening effects. The systems under investigation are analyzed numerically solving the Poisson equation in 3D via relaxation techniques with optimized algorithms for an extended set of boundary conditions. These include an open outer boundary, simulation of 2DEG systems and dielectric boundaries like the surface of a physical sample. The results show that for currently lithographically available feature sizes, the Coulomb interaction between the quantum bits is weak in general due to efficient screening in the planar geometry of 2DEG and top gates. The evaluated values are on the order of 1 μeV. Moreover, while it is not possible to turn off the qubit interaction completely, an effective tunability on the order of 50", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0607/0607759v1.pdf"}
{"id": "cond-mat0608001", "abstract": "  We calculate the finite-temperature local spectral weight (LSW) of a Luttinger liquid with an \"open\" (hard wall) boundary. Close to the boundary the LSW exhibits characteristic oscillations indicative of spin-charge separation. The line shape of the LSW is also found to have a Fano-like asymmetry, a feature originating from the interplay between electron-electron interaction and scattering off the boundary. Our results can be used to predict how edges and impurities influence scanning tunneling microscopy (STM) of one-dimensional electron systems at low temperatures and voltage bias. Applications to STM on single-walled carbon nanotubes are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0608/0608001v1.pdf"}
{"id": "cond-mat0609237", "abstract": "  We present explicit analytic, twice-differentiable expressions for the temperature-dependent anisotropic step line tension and step stiffness for the two principal surfaces of face-centered-cubic crystals, the square 001 and the hexagonal 111. These expressions improve on simple expressions that are valid only for low temperatures and away from singular orientations. They are well suited for implementation into numerical methods such as finite-element simulation of step evolution. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0609/0609237v2.pdf"}
{"id": "cond-mat0609374", "abstract": "  We consider a dilute gas of dipole moments in an arbitrary harmonic trap and treat both the short-range, isotropic delta-interaction and the long-range, anisotropic dipole-dipole interaction perturbatively. With this we calculate the leading shift of the critical temperature with respect to that of an ideal gas as a function of the relative orientation of the dipole moments with respect to the harmonic trap axes. In particular, we determine those magic angles, where the dipolar shift of the Bose-Einstein condensation temperature vanishes. Furthermore, we show for the parameters of the ongoing 52Cr-experiment in Stuttgart that this dipolar shift can be enhanced by increasing the number of particles, the geometrical mean trap frequency, and the anisotropy of the trap. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0609/0609374v2.pdf"}
{"id": "cond-mat0610810", "abstract": "  In this paper we study the interplay between interference effects in quantum dots (manifested through the appearance of Fano resonances in the conductance), and interactions taken into account in the self-consistent Hartree-Fock approximation. In the non-interacting case we find that interference may lead to the observation of more than one conductance peak per dot level as a function of an applied gate voltage. This may explain recent experimental findings, which were thought to be caused by interaction effects. For the interacting case we find a wide variety of different interesting phenomena. These include both monotonous and non-monotonous filling of the dot levels as a function of an applied gate voltage, which may occur continuously or even discontinuously. In many cases a combination of the different effects can occur in the same sample. The behavior of the population influences, in turn, the conductance lineshape, causing broadening and asymmetry of narrow peaks, and determining whether there will be a zero transmission point. We elucidate the essential role of the interference between the dot levels in determining these outcomes. The effects of finite temperatures on the results are also examined. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0610/0610810v1.pdf"}
{"id": "cond-mat0611088", "abstract": "  Since their introduction, Boolean networks have been traditionally studied in view of their rich dynamical behavior under different update protocols and for their qualitative analogy with cell regulatory networks. More recently, tools borrowed from statistical physics of disordered systems and from computer science have provided a more complete characterization of their equilibrium behavior. However, the largest part of the results have been obtained in the thermodynamic limit, which is often far from being reached when dealing with realistic instances of the problem. The numerical analysis presented here aims at comparing - for a specific family of models - the outcomes given by the heuristic belief propagation algorithm with those given by exhaustive enumeration. In the second part of the paper some analytical considerations on the validity of the annealed approximation are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0611/0611088v2.pdf"}
{"id": "cond-mat0612366", "abstract": "  We investigate theoretically the ground state of the FeMn binary alloy monolayer on the W(001) surface, the stability of different magnetic configurations (ferro/antiferromagnetic, disordered local moments, etc.) and estimate concentrations at which a transition occurs between different magnetic orders. The tight-binding linear muffin-tin orbital method combined with the coherent potential approximation is used to treat the surface alloy appropriately. We discuss the role of disorder on the phase transitions in surface alloys composed from two different 3d transition metals. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0612/0612366v1.pdf"}
{"id": "cond-mat0702690", "abstract": "  Results of analytic and numerical investigations of first-passage properties of equilibrium fluctuations of monatomic steps on a vicinal surface are reviewed. Both temporal and spatial persistence and survival probabilities, as well as the probability of persistent large deviations are considered. Results of experiments in which dynamical scanning tunneling microscopy is used to evaluate these first-passage properties for steps with different microscopic mechanisms of mass transport are also presented and interpreted in terms of theoretical predictions for appropriate models. Effects of discrete sampling, finite system size and finite observation time, which are important in understanding the results of experiments and simulations, are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0702/0702690v1.pdf"}
{"id": "cond-mat9604161", "abstract": "  Dispersion relations and polarizations for surface waves in infinite planar samples in the QHE regime are explicitly determined in the small wavevector limit in which the dielectric tensor can be considered as local. The wavelength and frequency regions of applicability of the results extends to the infrared region for typical experimental conditions. Then, standard samples with millimetric sizes seem to be able to support such excitations. Forced oscillations are also determined which should be generated in the 2DEG by external electromagnetic sources. They show an almost frequency independent wavevelength which decreases with the magnetic field. A qualitative model based in these solutions is also presented to describe a recently found new class of resonances appearing near the edge of a 2DEG in the QHE regime. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9604/9604161v3.pdf"}
{"id": "cond-mat9807343", "abstract": "  Variational Monte Carlo calculations of the quasielectron and quasihole excitation energies in the fractional quantum Hall effect have been carried out at filling fractions ν=1/3, 1/5, and 1/7. For the quasielectron both the trial wave function originally proposed by Laughlin and the composite fermion wave function proposed by Jain have been used. We find that for long-range Coulomb interactions the results obtained using these two wave functions are essentially the same, though the energy gap obtained using the composite fermion quasielectron is slightly smaller, and closer to extrapolated exact-diagonalization results. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9807/9807343v1.pdf"}
{"id": "cond-mat9810408", "abstract": "  A sandpile model with stochastic toppling rule is studied. The control parameters and the phase diagram are determined through a MF approach, the subcritical and critical regions are analyzed. The model is found to have some similarities with directed percolation, but the existence of different boundary conditions and conservation law leads to a different universality class, where the critical state is extended to a line segment due to self-organization. These results are supported with numerical simulations in one dimension. The present model constitute a simple model which capture the essential difference between ordinary nonequilibrium critical phenomena, like DP, and self-organized criticality. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9810/9810408v2.pdf"}
{"id": "cond-mat9811204", "abstract": "  Constant temperature molecular dynamics simulations were used to study solutions of flexible polyelectrolyte chains at nonzero concentrations with explicit counterions and unscreened coulombic interactions. Counterion condensation, measured via the self-diffusion coefficient of the counterions, is found to increase with polymer concentration, but contrary to the prediction of Manning theory, the renormalized charge fraction on the chains decreases with increasing Bjerrum length without showing any saturation. Scaling analysis of the radius of gyration shows that the chains are extended at low polymer concentrations and small Bjerrum lengths, while at sufficiently large Bjerrum lengths, the chains shrink to produce compact structures with exponents smaller than a gaussian chain, suggesting the presence of attractive intrachain interactions. A careful study of the radial distribution function of the center-of-mass of the polyelectrolyte chains shows clear evidence that effective interchain attractive interactions also exist in solutions of flexible polyelectrolytes, similar to what has been found for rodlike polyelectrolytes. Our results suggest that the broad maximum observed in scattering experiments is due to clustering of chains. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9811/9811204v1.pdf"}
{"id": "cond-mat9902272", "abstract": "  It is shown that nonadiabatic fluctuations of the soliton lattice in the spin-Peierls system CuGeO_3 lead to an important reduction of the NMR line widths. These fluctuations are the zero-point motion of the massless phasonic excitations. Furthermore, we show that the discrepancy of X-ray and NMR soliton widths can be understood as the difference between a distortive and a magnetic width. Their ratio is controlled by the frustration of the spin system. By this work, theoretical and experimental results can be reconciled in two important points. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9902/9902272v1.pdf"}
{"id": "cond-mat9908391", "abstract": "  We present analytic and numerical studies based on Landauer theory of conductance antiresonances of molecular wires. Our analytic treatment is a solution of the Lippmann-Schwinger equation for the wire that includes the effects of the non-orthogonality of the atomic orbitals on different atoms exactly. The problem of non-orthogonality is treated by solving the transport problem in a new Hilbert space which is spanned by an orthogonal basis. An expression is derived for the energies at which antiresonances should occur for a molecular wire connected to a pair of single-channel 1D leads. From this expression we identify two distinct mechanisms that give rise to antiresonances under different circumstances. The exact treatment of non-orthogonality in the theory is found to be necessary to obtain reliable results. Our numerical simulations extend this work to multichannel leads and to molecular wires connected to 3D metallic nanocontacts. They demonstrate that our analytic results also provide a good description of these more complicated systems provided that certain well-defined conditions are met. These calculations suggest that antiresonances should be experimentally observable in the differential conductance of molecular wires of certain types. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9908/9908391v1.pdf"}
{"id": "cs0205028", "abstract": "  NLTK, the Natural Language Toolkit, is a suite of open source program modules, tutorials and problem sets, providing ready-to-use computational linguistics courseware. NLTK covers symbolic and statistical natural language processing, and is interfaced to annotated corpora. Students augment and replace existing components, learn structured programming by example, and manipulate sophisticated models from the outset. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0205/0205028v1.pdf"}
{"id": "cs0305055", "abstract": "  An analytical formula for the probability distribution of stock-market returns, derived from the Heston model assuming a mean-reverting stochastic volatility, was recently proposed by Dragulescu and Yakovenko in Quantitative Finance 2002. While replicating their results, we found two significant weaknesses in their method to pre-process the data, which cast a shadow over the effective goodness-of-fit of the model. We propose a new method, more truly capturing the market, and perform a Kolmogorov-Smirnov test and a Chi Square test on the resulting probability distribution. The results raise some significant questions for large time lags – 40 to 250 days – where the smoothness of the data does not require such a complex model; nevertheless, we also provide some statistical evidence in favour of the Heston model for small time lags – 1 and 5 days – compared with the traditional Gaussian model assuming constant volatility. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0305/0305055v1.pdf"}
{"id": "cs0309028", "abstract": "  We present cTI, the first system for universal left-termination inference of logic programs. Termination inference generalizes termination analysis and checking. Traditionally, a termination analyzer tries to prove that a given class of queries terminates. This class must be provided to the system, for instance by means of user annotations. Moreover, the analysis must be redone every time the class of queries of interest is updated. Termination inference, in contrast, requires neither user annotations nor recomputation. In this approach, terminating classes for all predicates are inferred at once. We describe the architecture of cTI and report an extensive experimental evaluation of the system covering many classical examples from the logic programming termination literature and several Prolog programs of respectable size and complexity. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0309/0309028v1.pdf"}
{"id": "cs0509003", "abstract": "  The COmputational MODule Integrator (COMODI) is an initiative aiming at a component based framework, component developer tool and component repository for scientific computing. We identify the main ingredients to a solution that would be sufficiently appealing to scientists and engineers to consider alternatives to their deeply rooted programming traditions. The overall structure of the complete solution is sketched with special emphasis on the Component Developer Tool standing at the basis of COMODI. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0509/0509003v1.pdf"}
{"id": "cs0603064", "abstract": "  This paper considers the problem of guessing the realization of a finite alphabet source when some side information is provided. The only knowledge the guesser has about the source and the correlated side information is that the joint source is one among a family. A notion of redundancy is first defined and a new divergence quantity that measures this redundancy is identified. This divergence quantity shares the Pythagorean property with the Kullback-Leibler divergence. Good guessing strategies that minimize the supremum redundancy (over the family) are then identified. The min-sup value measures the richness of the uncertainty set. The min-sup redundancies for two examples - the families of discrete memoryless sources and finite-state arbitrarily varying sources - are then determined. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0603/0603064v2.pdf"}
{"id": "gr-qc0005113", "abstract": "  We reinvestigate the utility of time-independent constant mean curvature foliations for the numerical simulation of a single spherically-symmetric black hole. Each spacelike hypersurface of such a foliation is endowed with the same constant value of the trace of the extrinsic curvature tensor, K. Of the three families of K-constant surfaces possible (classified according to their asymptotic behaviors), we single out a sub-family of singularity-avoiding surfaces that may be particularly useful, and provide an analytic expression for the closest approach such surfaces make to the singularity. We then utilize a non-zero shift to yield families of K-constant surfaces which (1) avoid the black hole singularity, and thus the need to excise the singularity, (2) are asymptotically null, aiding in gravity wave extraction, (3) cover the physically relevant part of the spacetime, (4) are well behaved (regular) across the horizon, and (5) are static under evolution, and therefore have no “grid stretching/sucking” pathologies. Preliminary numerical runs demonstrate that we can stably evolve a single spherically-symmetric static black hole using this foliation. We wish to emphasize that this coordinatization produces K-constant surfaces for a single black hole spacetime that are regular, static and stable throughout their evolution. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0005/0005113v2.pdf"}
{"id": "gr-qc0105015", "abstract": "  We consider principal moments of inertia of axisymmetric, magnetically deformed stars in the context of general relativity. The general expression for the moment of inertia with respect to the symmetric axis is obtained. The numerical estimates are derived for several polytropic stellar models. We find that the values of the principal moments of inertia are modified by a factor of 2 at most from Newtonian estimates. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0105/0105015v1.pdf"}
{"id": "gr-qc0109018", "abstract": "  We study the collision of two slowly rotating, initially non boosted, black holes in the close limit. A “punctures” modification of the Bowen - York method is used to construct conformally flat initial data appropriate to the problem. We keep only the lowest nontrivial orders capable of giving rise to radiation of both gravitational energy and angular momentum. We show that even with these simplifications an extension to higher orders of the linear Regge-Wheeler-Zerilli black hole perturbation theory, is required to deal with the evolution equations of the leading contributing multipoles. This extension is derived, together with appropriate extensions of the Regge-Wheeler and Zerilli equations. The data is numerically evolved using these equations, to obtain the asymptotic gravitational wave forms and amplitudes. Expressions for the radiated gravitational energy and angular momentum are derived and used together with the results of the numerical evolution to provide quantitative expressions for the relative contribution of different terms, and their significance is analyzed. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0109/0109018v2.pdf"}
{"id": "gr-qc0111007", "abstract": "  In this review we examine the dynamics and gravitational wave detectability of rotating strained neutron stars. The discussion is divided into two halves: triaxial stars, and precessing stars. We summarise recent work on how crustal strains and magnetic fields can sustain triaxiality, and suggest that Magnus forces connected with pinned superfluid vortices might contribute to deformation also. The conclusions that could be drawn following the successful gravitational wave detection of a triaxial star are discussed, and areas requiring further study identified. The latest ideas regarding free precession are then outlined, and the recent suggestion of Middleditch et al (2000a,b) that the remnant of SN1987A contains a freely precessing star, spinning-down by gravitational wave energy loss, is examined critically. We describe what we would learn about neutron stars should the gravitational wave detectors prove this hypothesis to be correct. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0111/0111007v1.pdf"}
{"id": "gr-qc0209109", "abstract": "  After an introduction on phenomena due to spin and mass-energy currents on clocks and photons, we review the 1995-2001 measurements of the gravitomagnetic field of Earth and Lense-Thirring effect obtained by analyzing the orbits of the two laser-ranged satellites LAGEOS and LAGEOS II; this method has provided a direct measurement of Earth's gravitomagnetism with accuracy of the order of 20 ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0209/0209109v2.pdf"}
{"id": "gr-qc0303052", "abstract": "  We study characteristic (quasinormal) modes of a D-dimensional Schwarzshild black hole. It proves out that the real parts of the complex quasinormal modes, representing the real oscillation frequencies, are proportional to the product of the number of dimensions and inverse horizon radius ∼ D r_0^-1. The asymptotic formula for large multipole number l and arbitrary D is derived. In addition the WKB formula for computing QN modes, developed to the 3rd order beyond the eikonal approximation, is extended to the 6th order here. This gives us an accurate and economic way to compute quasinormal frequencies. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0303/0303052v6.pdf"}
{"id": "gr-qc0308021", "abstract": "  Quantum decoherence can arise due to classical fluctuations in the parameters which define the dynamics of the system. In this case decoherence, and complementary noise, is manifest when data from repeated measurement trials are combined. Recently a number of authors have suggested that fluctuations in the space-time metric arising from quantum gravity effects would correspond to a source of intrinsic noise, which would necessarily be accompanied by intrinsic decoherence. This work extends a previous heuristic modification of Schrödinger dynamics based on discrete time intervals with an intrinsic uncertainty. The extension uses unital semigroup representations of space and time translations rather than the more usual unitary representation, and does the least violence to physically important invariance principles. Physical consequences include a modification of the uncertainty principle and a modification of field dispersion relations, in a way consistent with other modifications suggested by quantum gravity and string theory . ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0308/0308021v1.pdf"}
{"id": "gr-qc0410104", "abstract": "  We propose a structure called a causal site to use as a setting for quantum geometry, replacing the underlying point set. The structure has an interesting categorical form, and a natural \"tangent 2-bundle,\" analogous to the tangent bundle of a smooth manifold. Examples with reasonable finiteness conditions have an intrinsic geometry, which can approximate classical solutions to general relativity. We propose an approach to quantization of causal sites as well. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0410/0410104v2.pdf"}
{"id": "gr-qc0411041", "abstract": "  We investigate a condensed matter “black hole” analogue, taking the Gross-Pitaevskii (GP) equation as a starting point. The linearized GP equation corresponds to a wave equation on a black hole background, giving quasinormal modes under some appropriate conditions. We suggest that we can know the detailed characters and corresponding geometrical information about the acoustic black hole by observing quasinormal ringdown waves in the low temperature condensed matters. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0411/0411041v4.pdf"}
{"id": "gr-qc9710006", "abstract": "  A quantum mechanical description of black hole states proposed recently within non-perturbative quantum gravity is used to study the emission and absorption spectra of quantum black holes. We assume that the probability distribution of states of the quantum black hole is given by the “area” canonical ensemble, in which the horizon area is used instead of energy, and use Fermi's golden rule to find the line intensities. For a non-rotating black hole, we study the absorption and emission of s-waves considering a special set of emission lines. To find the line intensities we use an analogy between a microscopic state of the black hole and a state of the gas of atoms. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/9710/9710006v2.pdf"}
{"id": "gr-qc9902070", "abstract": "  The purpose of this paper is to further investigate the solution space of self-similar spherically symmetric perfect-fluid models and gain deeper understanding of the physical aspects of these solutions. We achieve this by combining the state space description of the homothetic approach with the use of the physically interesting quantities arising in the comoving approach. We focus on three types of models. First, we consider models that are natural inhomogeneous generalizations of the Friedmann Universe; such models are asymptotically Friedmann in their past and evolve fluctuations in the energy density at later times. Second, we consider so-called quasi-static models. This class includes models that undergo self-similar gravitational collapse and is important for studying the formation of naked singularities. If naked singularities do form, they have profound implications for the predictability of general relativity as a theory. Third, we consider a new class of asymptotically Minkowski self-similar spacetimes, emphasizing that some of them are associated with the self-similar solutions associated with the critical behaviour observed in recent gravitational collapse calculations. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/9902/9902070v3.pdf"}
{"id": "gr-qc9904015", "abstract": "  A single spherical antenna is capable of measuring the direction and polarization of a gravitational wave. It is possible to solve the inverse problem using only linear algebra even in the presence of noise. The simplicity of this solution enables one to explore the error on the solution using standard techniques. In this paper we derive the error on the direction and polarization measurements of a gravitational wave. We show that the solid angle error and the uncertainty on the wave amplitude are direction independent. We also discuss the possibility of determining the polarization amplitudes with isotropic sensitivity for any given gravitational wave source. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/9904/9904015v1.pdf"}
{"id": "gr-qc9912102", "abstract": "  Interacting white dwarf binary star systems, including helium cataclysmic variable (HeCV) systems, are expected to be strong sources of gravitational radiation, and should be detectable by proposed space-based laser interferometer gravitational wave observatories such as LISA. Several HeCV star systems are presently known and can be studied optically, which will allow electromagnetic and gravitational wave observations to be correlated. Comparisons of the phases of a gravitational wave signal and the orbital light curve from an interacting binary white dwarf star system can be used to bound the mass of the graviton. Observations of typical HeCV systems by LISA could potentially yield an upper bound on the inverse mass of the graviton as strong as h/m_g = λ_g > 1 × 10^15 km (m_g < 1 × 10^-24 eV), more than two orders of magnitude better than present solar system derived bounds. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/9912/9912102v1.pdf"}
{"id": "hep-ex0209059", "abstract": "  A Photon Collider will provide unique opportunities to study the SM Higgs boson and to determine its properties. MSSM Higgs bosons can be discovered at the Photon Collider for scenarios where they might escape detection at the LHC. As an example for the many other physics topics which can be studied at a Photon Collider, recent results on Non-Commutative Field Theories are also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ex/pdf/0209/0209059v1.pdf"}
{"id": "hep-ex0303038", "abstract": "  Using aerogel as radiator and multianode PMTs for photon detection, a proximity focusing Cherenkov ring imaging detector has been constructed and tested in the KEK π2 beam. The aim is to experimentally study the basic parameters such as resolution of the single photon Cherenkov angle and number of detected photons per ring. The resolution obtained is well approximated by estimates of contributions from pixel size and emission point uncertainty. The number of detected photons per Cherenkov ring is in good agreement with estimates based on aerogel and detector characteristics. The values obtained turn out to be rather low, mainly due to Rayleigh scattering and to the relatively large dead space between the photocathodes. A light collection system or a higher fraction of the photomultiplier active area, together with better quality aerogels are expected to improve the situation. The reduction of Cherenkov yield, for charged particle impact in the vicinity of the aerogel tile side wall, has also been measured. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ex/pdf/0303/0303038v1.pdf"}
{"id": "hep-ex9810025", "abstract": "  This article describes calculations and measurements of space charge effects due to high rate irradiation in high resolution drift tubes. Two main items are studied: the reduction of the gas gain and changes of the drift time. Whereas the gain reduction is similar for all gases and unavoidable, the drift time changes depend on the kind of gas that is used. The loss in resolution due to high particle rate can be minimized with a suitable gas. This behaviour is calculable, allowing predictions for new gas mixtures. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ex/pdf/9810/9810025v1.pdf"}
{"id": "hep-lat0212036", "abstract": "  We study the abelian color flux of two- and three-quark systems in the maximally abelian gauge in lattice QCD with dynamical fermions. We find that the abelian flux tube formed between quark and antiquark is very much the same as in quenched QCD up to quark separations of R∼ 2fm. The profile of the color electric field in three-quark system suggests Y ansatz, which might be interpreted as the result of the vacuum pressure in the confined phase. In order to clarify the flux structure, we investigate the color electric field of the three-quark system splittting the abelian gauge field into the monopole and photon parts. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/0212/0212036v1.pdf"}
{"id": "hep-lat0310003", "abstract": "  We review the calculation of moments of both the polarized and unpolarized parton distribution functions of the nucleon in lattice QCD, and in particular their extrapolation to the physical region. We also discuss the reconstruction of the x dependence of the valence quark distributions in the nucleon from a finite number of lattice moments. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/0310/0310003v1.pdf"}
{"id": "hep-lat0511040", "abstract": "  Results for Monte Carlo calculations of the electromagnetic vector and scalar form factors of the pion in a quenched simulation are presented. We work with two different lattice volumes up to a spatial size of 2.4 fm at a lattice spacing of 0.148 fm. The pion form factors in the space-like region are determined for pion masses down to 340 MeV. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/0511/0511040v2.pdf"}
{"id": "hep-ph0005313", "abstract": "  We present a model-independent study of the effects of a neutral Higgs boson without definite CP-parity in the process γγ→ tt̅ around the mass pole of the Higgs boson. Near the resonance pole, the interference between the Higgs-exchange and the continuum amplitudes can be sizable if the photon beams are polarized and helicities of the top and anti-top quarks are measured. Study of these interference effects enables one to determine the CP property of the Higgs boson completely. An example of the complete determination is demonstrated in the context of the minimal supersymmetric standard model. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0005/0005313v1.pdf"}
{"id": "hep-ph0211052", "abstract": "  The parallel sessions of the working group 3 were devoted to the discussions of short-baseline neutrino physics program at neutrino factories. First, possible studies of parton distribution functions (PDFs), in particular nuclear and polarized PDFs, are discussed in this summary. Second, the extractions of alpha_s from sum rules and structure functions of deep-inelastic neutrino-nucleon scattering, higher-order perturbative QCD corrections and estimates of high-twist effects are summarized. Third, the situation of the observed NuTeV sin^2 theta_W anomaly is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0211/0211052v1.pdf"}
{"id": "hep-ph0302202", "abstract": "  The matrix element of a bound electron interacting with the nucleus through exchange of a Z boson is studied for the gauge invariant case of 2s_1/2-2p_1/2 transitions in hydrogenic ions. The QED radiative correction to the matrix element, which is -α/2π in lowest order, is calculated to all orders in Zα using exact propagators. Previous calculation of the first-order binding correction are confirmed both analytically and by fitting the exact function at low Z. Consequences for the interpretation of parity nonconservation in cesium are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0302/0302202v1.pdf"}
{"id": "hep-ph0306008", "abstract": "  In models with large extra dimensions, particle collisions with center-of-mass energy larger than the fundamental gravitational scale can generate nonperturbative gravitational objects. Since cosmic rays have been observed with energies above 10^8 TeV, gravitational effects in the TeV energy range can, in principle, be observed by ultrahigh energy cosmic ray detectors. We consider the interaction of ultrahigh energy neutrinos in the atmosphere and compare extensive air showers from TeV black hole formation and fragmentation with standard model processes. Departures from the standard model predictions arise in the interaction cross sections and in the multiplicity of secondary particles. Large theoretical uncertainties in the black hole cross section weaken attempts to constrain TeV gravity based solely on differences between predicted and observed event rates. The large multiplicity of secondaries in black hole fragmentation enhances the detectability of TeV gravity effects. We simulate TeV black hole air showers using PYTHIA and AIRES, and find that black hole-induced air showers are quite distinct from standard model air showers. However, the limited amount of information registered by realistic detectors together with large air shower fluctuations limit in practice the ability to distinguish TeV gravity events from standard model events in a shower by shower case. We discuss possible strategies to optimize the detectability of black hole events and propose a few unique signatures that may allow future high statistics detectors to separate black hole from standard model events. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0306/0306008v2.pdf"}
{"id": "hep-ph0307362", "abstract": "  It is pointed out that heavy top quark mass can be attributed to a singular normalization of its kinetic term, in which rescaling into canonical one yields large top Yukawa coupling. We pursue this novel possibility in a democratic mass matrix model where only the normalization of the third generation can be different from that of the other two generations. With diagonal breaking of democratic S_3 symmetry, we show that the singular normalization for the top quark is essential to reproduce observed quark masses and mixing angles. We also briefly argue other applications of this mechanism. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0307/0307362v1.pdf"}
{"id": "hep-ph0402232", "abstract": "  We study cosmological formation of D-term strings, axionic strings, domain walls and Q-balls in braneworld models of the Hanany-Witten type. For the D-term strings, we show that the strings are the daughter branes extended between mother branes. We show that the domain walls can be produced by conventional cosmological phase transitions. In this case, the formation of the domain walls is induced by the continuous deformation of the branes, which means that they are not created as daughter branes. First we consider classical configurations of the axionic strings and the domain walls, then we investigate the quantum effect of the brane dynamics. We also study brane Q-balls and show how they can be distinguished from conventional Q-balls. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0402/0402232v4.pdf"}
{"id": "hep-ph0505073", "abstract": "  I present our recent results on the critical end point in the μ_B-T phase diagram of QCD with two flavours of light dynamical quarks and compare them with similar results from other groups. Implications for a possible energy scan at the RHIC are discussed. I also comment briefly on the new results of great relevance to heavy ion collisions from finite temperature lattice QCD simulations on speed of sound, specific heat and on the fate of J/ψ. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0505/0505073v1.pdf"}
{"id": "hep-ph0612091", "abstract": "  We reproduce the DIS measurements of the proton structure function at high energy from the dipole model in momentum space. To model the dipole-proton forward scattering amplitude, we use the knowledge of asymptotic solutions of the Balitsky-Kovchegov equation, describing high-energy QCD in the presence of saturation effects. We compare our results with the previous analysis in coordinate space and discuss possible extensions of our approach. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0612/0612091v1.pdf"}
{"id": "hep-ph9504315", "abstract": "  A set of procedures is given for avoiding the spurious anomalies that are generated when the 't Hooft - Veltman definition of gamma5 is used in conjunction with renormalization by minimal subtraction. These procedures are derived from the standard procedure, which requires in addition various finite renormalizations to remove spurious violations of chiral symmetry. They apply to open fermion lines, including flavor changing currents, to closed fermion loops, including those which contain true anomalous currents, and to anomalous loops connected to open fermion lines, to all orders in QCD. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9504/9504315v1.pdf"}
{"id": "hep-ph9507281", "abstract": "  Nuclear interactions of antiprotons in atomic states are discussed. The total as well as partial widths for single nucleon capture events are calculated. These are compared to the X-ray and recent single nucleon capture data. The rates of the neutron or proton captures test nuclear density distributions at the extreme nuclear surface. Recently found cases of neutron and proton haloes are analysed. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9507/9507281v2.pdf"}
{"id": "hep-ph9705331", "abstract": "  It has been suggested by Bartlett and Hall that our universe may have the critical density in baryons by virtue of specific interactions with a `shadow' world. We show that this possibility is severely constrained by primordial nucleosynthesis, stellar evolution and the thermalization of the cosmic microwave background. In particular, recent observations of small angular-scale anisotropy in the cosmic microwave background conclusively rule out all such baryon-dominated cosmologies. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9705/9705331v1.pdf"}
{"id": "hep-ph9809513", "abstract": "  We apply analytic perturbation theory to the Gross–Llewellyn Smith sum rule. We study the Q^2 evolution and the renormalization scheme dependence of the analytic three-loop QCD correction to this sum rule, and demonstrate that the results are practically renormalization scheme independent and lead to rather different Q^2 evolution than the standard perturbative correction possesses. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9809/9809513v1.pdf"}
{"id": "hep-ph9905326", "abstract": "  We calculate the ratios E2/M1 and C2/M1 for the electroproduction of the Δ(1232) in the region of photon virtuality 0<-q^2<1 GeV^2. The magnetic dipole amplitude M1 is also presented. The theory used is the chiral quark-soliton model, which is based in the instanton vaccum of the QCD. The calculations are performed in flavor SU(2) and SU(3) taking rotational (1/N_c) corrections into account. The results for the ratios agree qualitatively with the available data, although the magnitude of both ratios seems to underestimate the latest experimental results. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9905/9905326v2.pdf"}
{"id": "hep-th0005284", "abstract": "  Wigner's method of induced representations is applied to the N=1 super-Poincare group, and by using a state corresponding to the basic vector of the little group as a Clifford vacuum we show that the spin operator of a supersymmetric point particle obeys Wigner's constraints. As dynamical variables for the particle we use canonical coordinates on the symmetry group manifold. The physical phase space is then constructed using a vielbein formalism. We find that the Casalbuoni-Brink-Schwarz superparticle appears as a special case of our general construction. Finally, the theory is reformulated as a gauge theory where the gauge freedom corresponds to the choice of spin constraints or, equivalently, the free choice of relativistic center of mass. In a special case the gauge symmetry reduces to the well known kappa-symmetry. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0005/0005284v1.pdf"}
{"id": "hep-th0207138", "abstract": "  The Casimir effect due to conformally coupled bulk scalar fields on background of conformally flat brane-world geometries is investigated. In the general case of mixed boundary conditions formulae are derived for the vacuum expectation values of the energy-momentum tensor and vacuum forces acting on boundaries. The special case of the AdS bulk is considered and the application to the Randall-Sundrum scenario is discussed. The possibility for the radion stabilization by the vacuum forces is demonstrated. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0207/0207138v2.pdf"}
{"id": "hep-th0307294", "abstract": "  We investigate the Hawking radiation in the gauge-Higgs-Yukawa theory. The ballistic model is proposed as an effective description of the system. We find that a spherical domain wall around the black hole is formed by field dynamics rather than thermal phase-transition. The formation is a general property of the black hole whose Hawking temperature is equal to or greater than the energy scale of the theory. The formation of the electroweak wall and that of the GUT wall are shown. We also find a phenomenon of the spontaneous charging-up of the black hole by the wall. The Hawking radiation drives a mechanism of the charge-transportation into the black hole when C- and CP-violation are assumed. The mechanism can strongly transport the hyper-charge into a black hole of the electroweak scale. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0307/0307294v2.pdf"}
{"id": "hep-th0404244", "abstract": "  I solve for the behavior of scalars in Lorentzian AdS with time dependent boundary conditions, focusing in particular on the dilaton. This corresponds, via the AdS-CFT correspondence, to considering a gauge theory with a time dependent coupling. Changes which keep the gauge coupling nonzero result in finite but physically interesting states in the bulk, including black holes, while sending the gauge coupling to zero appears to produce a cosmological singularity in the bulk. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0404/0404244v1.pdf"}
{"id": "hep-th0406014", "abstract": "  We compare the standard and geometric approaches to quantum Liouville theory on the pseudosphere by performing perturbative calculations of the one and two point functions up to the third order in the coupling constant. The choice of the Hadamard regularization within the geometric approach leads to a discrepancy with the standard approach. On the other hand, we find complete agreement between the results of the standard approach and the bootstrap conjectures for the one point function and the auxiliary two point function. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0406/0406014v1.pdf"}
{"id": "hep-th0508246", "abstract": "  Strong coupling expansion is computed for the Einstein equations in vacuum in the Arnowitt-Deser-Misner (ADM) formalism. The series is given by the duality principle in perturbation theory as presented in [M.Frasca, Phys. Rev. A 58, 3439 (1998)]. An example of application is also given for a two-dimensional model of gravity expressed through the Liouville equation showing that the expansion is not trivial and consistent with the exact solution, in agreement with the general analysis. Application to the Einstein equations in vacuum in the ADM formalism shows that the spacetime near singularities is driven by space homogeneous equations. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0508/0508246v3.pdf"}
{"id": "hep-th0509116", "abstract": "  We show that the light-front vaccum is not trivial, and the Fock space for positive energy quanta solutions is not complete. As an example of this non triviality we have calculated the electromagnetic current for scalar bosons in the background field method were the covariance is restored through considering the complete Fock space of solutions. We also show thus that the method of \"dislocating the integration pole\" is nothing more than a particular case of this, so that such an \"ad hoc\" prescription can be dispensed altogether if we deal with the whole Fock space. In this work we construct the electromagnetic current operator for a system composed of two free bosons. The technique employed to deduce these operators is through the definition of global propagators in the light front when a background electromagnetic field acts on one of the particles. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0509/0509116v2.pdf"}
{"id": "hep-th0510102", "abstract": "  We determine the semiclassical energy levels for the ϕ^4 field theory in the broken symmetry phase on a 2D cylindrical geometry with antiperiodic boundary conditions by quantizing the appropriate finite–volume kink solutions. The analytic form of the kink scaling functions for arbitrary size of the system allows us to describe the flow between the twisted sector of c=1 CFT in the UV region and the massive particles in the IR limit. Kink-creating operators are shown to correspond in the UV limit to disorder fields of the c=1 CFT. The problem of the finite–volume spectrum for generic 2D Landau–Ginzburg models is also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0510/0510102v1.pdf"}
{"id": "hep-th0609045", "abstract": "  We analyze the Ricci flow of a noncompact metric that describes a two-dimensional black hole. We consider entanglement entropy of a 2d black hole which is due to the quantum correlations between two subsystems: one is inside and the other is outside the black hole horizon. It is demonstrated that the entanglement entropy is monotonic along the Ricci flow. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0609/0609045v1.pdf"}
{"id": "hep-th9511136", "abstract": "  We propose a possible internal structure for a Schwarzschild black hole resulting from the creation of multiple de Sitter universes with lightlike boundaries when the curvature reaches Planckian values. The intersection of the boundaries is studied and a scenario leading to disconnected de Sitter universes is proposed. The application to the information loss problem is then discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/9511/9511136v1.pdf"}
{"id": "math0209298", "abstract": "  We study the property of a normal scheme, that the complement of every hypersurface is an affine scheme. To this end we introduce the affine class group. It is a factor group of the divisor class group and measures the deviation from this property. We study the behaviour of the affine class group under faithfully flat extensions and under the formation of products, and we compute it for different classes of rings. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0209/0209298v1.pdf"}
{"id": "math0212415", "abstract": "  Many problems in physics, material sciences, chemistry and biology can be abstractly formulated as a system that navigates over a complex energy landscape of high or infinite dimensions. Well-known examples include phase transitions of condensed matter, conformational changes of biopolymers, and chemical reactions. The energy landscape typically exhibits multiscale features, giving rise to the multiscale nature of the dynamics. This is one of the main challenges that we face in computational science. In this report, we will review the recent work done by scientists from several disciplines on probing such energy landscapes. Of particular interest is the analysis and computation of transition pathways and transition rates between metastable states. We will then present the string method that has proven to be very effective for some truly complex systems in material science and chemistry. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0212/0212415v1.pdf"}
{"id": "math0312160", "abstract": "  Physical geometry studies mutual disposition of geometrical objects and points in space, or space-time, which is described by the distance function d, or by the world function σ =d^2/2. One suggests a new general method of the physical geometry construction. The proper Euclidean geometry is described in terms of its world function σ_E. Any physical geometry 𝒢 is obtained from the Euclidean geometry as a result of replacement of the Euclidean world function σ_E by the world function σ of 𝒢. This method is very simple and effective. It introduces a new geometric property: nondegeneracy of geometry. Using this method, one can construct deterministic space-time geometries with primordially stochastic motion of free particles and geometrized particle mass. Such a space-time geometry defined properly (with quantum constant as an attribute of geometry) allows one to explain quantum effects as a result of the statistical description of the stochastic particle motion (without a use of quantum principles). ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0312/0312160v3.pdf"}
{"id": "math0504171", "abstract": "  Precise knowledge of X-ray diffraction profile shape is crucial in the investigation of the properties of matter in crystals powder. Line-broadening analysis is a pre-processing step in most of the full powder pattern fitting softwares. Final result of line-broadening analysis strongly depends on preliminary three steps: Noise filtering, removal of background signal and peak fitting. In this work a new model independent procedure for two of the aforementioned steps (background suppression and peak fitting) is presented. The former is dealt with by using morphological mathematics, while the latter relies on the Hankel Lanczos Singular Value Decomposition technique. Real X-ray powder diffraction (XRPD) intensity profiles of Ceria samples are used to test the performance of the proposed procedure. Results show the robustness of this approach and its capability of efficiently improving the disentangling of instrumental broadening. These features make the proposed approach an interesting and user-friendly tool for the pre-processing of XRPD data. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0504/0504171v1.pdf"}
{"id": "mtrl-th9508008", "abstract": "  A recently proposed linear-scaling scheme for density-functional pseudopotential calculations is described in detail. The method is based on a formulation of density functional theory in which the ground state energy is determined by minimization with respect to the density matrix, subject to the condition that the eigenvalues of the latter lie in the range [0,1]. Linear-scaling behavior is achieved by requiring that the density matrix should vanish when the separation of its arguments exceeds a chosen cutoff. The limitation on the eigenvalue range is imposed by the method of Li, Nunes and Vanderbilt. The scheme is implemented by calculating all terms in the energy on a uniform real-space grid, and minimization is performed using the conjugate-gradient method. Tests on a 512-atom Si system show that the total energy converges rapidly as the range of the density matrix is increased. A discussion of the relation between the present method and other linear-scaling methods is given, and some problems that still require solution are indicated. ", "pdf_url": "gs://arxiv-dataset/arxiv/mtrl-th/pdf/9508/9508008v1.pdf"}
{"id": "mtrl-th9603002", "abstract": "  Due to the improvement of computer power and the development of efficient algorithms it is now possible to combine high-dimensional quantum dynamical calculations of the dissociative adsorption of molecular beams with reliable ab-initio potential energy surfaces (PES). In this brief review two recent examples of such studies of the systems H_2/Cu(111), where adsorption is hindered by a noticeable energy barrier, and H_2/Pd(100), where activated as well as non-activated paths to adsorption exist, are presented. The effect of lateral surface corrugations on the sticking probability in the tunneling and the classical regime and the role of additional parallel momentum are discussed in the context of the H_2/Cu(111) results. For the system H_2/Pd(100) it is shown that the initial decrease of the sticking probability with increasing kinetic energy, which is usually attributed to a precursor mechanism, can be explained by dynamical steering. In addition, the influence of rotation on the adsorption and desorption dynamics is examined. ", "pdf_url": "gs://arxiv-dataset/arxiv/mtrl-th/pdf/9603/9603002v1.pdf"}
{"id": "nlin0103053", "abstract": "  We consider (2+1)-dimensional beams, whose transverse size may be comparable to or smaller than the carrier wavelength, on the basis of an extended version of the nonlinear Schrödinger equation derived from the Maxwell`s equations. As this equation is very cumbersome, we also study, in parallel to it, its simplified version which keeps the most essential term: the term which accounts for the nonlinear diffraction. The full equation additionally includes terms generated by a deviation from the paraxial approximation and by a longitudinal electric-field component in the beam. Solitary-wave stationary solutions to both the full and simplified equations are found, treating the terms which modify the nonlinear Schrödinger equation as perturbations. Within the framework of the perturbative approach, a conserved power of the beam is obtained in an explicit form. It is found that the nonlinear diffraction affects stationary beams much stronger than nonparaxiality and longitudinal field. Stability of the beams is directly tested by simulating the simplified equation, with initial configurations taken as predicted by the perturbation theory. The numerically generated solitary beams are always stable and never start to collapse, although they display periodic internal vibrations, whose amplitude decreases with the increase of the beam power. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0103/0103053v1.pdf"}
{"id": "nlin0309026", "abstract": "  A chaotic autonomous Hamiltonian systems, perturbed by small damping and small external force, harmonically dependent on time, can acquire a strange attractor with properties similar to that of the canonical distribution - the Gibbs attractor. The evolution of the energy in such systems can be described as the energy diffusion. For the nonlinear Pullen - Edmonds oscillator with two degrees of freedom the properties of the Gibbs attractor and their dependence on parameters of the perturbation are studied both analytically and numerically. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0309/0309026v1.pdf"}
{"id": "nlin0404060", "abstract": "  Dynamical tunnelling is a quantum phenomenon where a classically forbidden process occurs, that is prohibited not by energy but by another constant of motion. The phenomenon of dynamical tunnelling has been recently observed in a sodium Bose-Einstein condensate. We present a detailed analysis of these experiments using numerical solutions of the three dimensional Gross-Pitaevskii equation and the corresponding Floquet theory. We explore the parameter dependency of the tunnelling oscillations and we move the quantum system towards the classical limit in the experimentally accessible regime. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0404/0404060v1.pdf"}
{"id": "nlin0610044", "abstract": "  Lotka Volterra model and its modified forms have long become a major area of interest for periodic motions in nonlinear systems with competitive species. The model given by Volterra shows that its periodicity is dependent on initial condition. This characteristics allows us to calculate the effect of periodic seasonal changes on population densities of different species ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0610/0610044v1.pdf"}
{"id": "nucl-ex0701048", "abstract": "  Measurements of intermediate pT (1.5 < pT < 5.0 GeV/c) identified particle distributions in heavy ion collisions at SPS and RHIC energies display striking dependencies on the number of constituent quarks in the corresponding hadron. One finds that elliptic flow at intermediate pT follows a constituent quark scaling law as predicted by models of hadron formation through coalescence. In addition, baryon production is also found to increase with event multiplicity much faster than meson production. The rate of increase is similar for all baryons, and seemingly independent of mass. This indicates that the number of constituent quarks determines the multiplicity dependence of identified hadron production at intermediate pT. We review these measurements and interpret the experimental findings. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/0701/0701048v1.pdf"}
{"id": "nucl-ex9810015", "abstract": "  The energy and nuclear mass dependences of the total hadronic cross section in the energy range 0.5-2.6 GeV have been measured at Bonn using the SAPHIR tagged photon beam. The measurement, performed on C, Al, Cu, Sn and Pb, provides the first photoabsorption data in the region 1.2-1.7 GeV. The results show a significant reduction of the photoabsorption strength on the bound nucleon compared to the free nucleon case in the whole energy region. Above 1.2 GeV this reduction decreases with the nuclear density and can be interpreted as a signature of a low energy onset of the shadowing effect. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/9810/9810015v1.pdf"}
{"id": "nucl-th0212107", "abstract": "  In the present paper we investigate incoherent rho^0 electroproduction off complex nuclei. We derive a novel, simple expression for the incoherent electroproduction cross section in which one can clearly separate the final state interactions of the reaction products from the 'initial state interactions' of the photon that give rise to nuclear shadowing. In the special case of purely absorptive final state interactions we deduce from our expression the known Glauber result. A more realistic treatment of the final state interactions within a transport model is then used to compare our predictions with experimental data from the HERMES experiment. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0212/0212107v2.pdf"}
{"id": "nucl-th0305050", "abstract": "  The nuclear liquid-gas phase transition of the system in ideal thermal equilibrium is studied with antisymmetrized molecular dynamics. The time evolution of a many-nucleon system confined in a container is solved for a long time to get a microcanonical ensemble of a given energy and volume. The temperature and the pressure are extracted from this ensemble and the caloric curves are constructed. The present work is the first time that a microscopic dynamical model which describes nuclear multifragmentation reactions well is directly applied to get the nuclear caloric curve. The obtained constant pressure caloric curves clearly show the characteristic feature of the liquid-gas phase transition, namely negative heat capacity (backbending), which is expected for the phase transition in finite systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0305/0305050v2.pdf"}
{"id": "nucl-th0412051", "abstract": "  Recent experimental measurements of high p_T hadron spectra and jet correlation at RHIC are analyzed within a parton model which incoporates initial jet production and final propagation in heavy-ion collisions. The suppresion of single hadron spectra, back-to-back correlation, their centrality dependence and azimuthal anisotropy point to a dense matter with an initial parton density about 30 times of that in a cold heavy nucleus. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0412/0412051v1.pdf"}
{"id": "nucl-th0501080", "abstract": "  The surface partition of large clusters is studied analytically within a frame-work of the “Hills and Dales Model”. Three formulations are solved exactly by using the Laplace-Fourier transformation method. In the limit of small amplitude deformations, the “Hills and Dales Model” gives upper and lower bounds for the surface entropy coefficient of large clusters. A comparison with the 2- and 3-dimensional Ising model surface entropy coefficients is made. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0501/0501080v1.pdf"}
{"id": "nucl-th0606001", "abstract": "  We discuss quantum effects in the diffusion process which is used to describe the shape evolution from the touching configuration of fusing two nuclei to a compound nucleus. Applying the theory with quantum effects to the case where the potential field, the mass and friction parameters are adapted to realistic values of heavy-ion collisions, we show that the quantum effects play significant roles at low temperatures which are relevant to the synthesis of superheavy elements. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0606/0606001v1.pdf"}
{"id": "nucl-th9802013", "abstract": "  The production of ω-mesons in proton-proton collisions for proton incident energies up to 2.2 GeV is investigated within a meson-exchange model of hadronic interactions.   We find a large cancellation between the dominant πρω meson-exchange current and nucleonic current contributions. A comparison with preliminary data from SATURNE calls for the inclusion of off-shell form factors at the NNω and πρω production vertices. Due to the present lack of knowledge of these form factors, together with the destructive interference mentioned above, the relative magnitude of the nucleonic and meson-exchange current contributions cannot be determined from existing total cross section data. However, it is shown that the angular distribution of the produced ω-mesons provides an unique and clear signature of the magnitude of these currents, thus allowing one to disentangle these two basic reaction mechanisms. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/9802/9802013v1.pdf"}
{"id": "nucl-th9809069", "abstract": "  After a historical review, I present the progress in the field of realistic NN potentials that we have seen in recent years. A new generation of very quantitative (high-quality/high-precision) NN potentials has emerged. These potentials will serve as reliable input for microscopic nuclear structure calculations and will allow for a systematic investigation of off-shell effects. The issue of three-nucleon forces is also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/9809/9809069v1.pdf"}
{"id": "patt-sol9605002", "abstract": "  We show that the linear-stability analysis of the birth of Faraday waves on the surface of a fluid is simplified considerably when the fluid container is driven by a triangle waveform rather than by a sine wave. The calculation is simple enough to use in an undergraduate course on fluid dynamics or nonlinear dynamics. It is also an attractive starting point for a nonlinear analysis. ", "pdf_url": "gs://arxiv-dataset/arxiv/patt-sol/pdf/9605/9605002v1.pdf"}
{"id": "physics0008201", "abstract": "  We present numerical procedures for analyzing the properties of periodic structures and associated couplers based upon time domain simulation. Simple post processing procedures are given for determining Brillouin diagrams and complex field distributions of the traveling wave solutions, and the reflection coefficient of the traveling waves by the input and output. The availability of the reflection coefficient information facilitates a systematic and efficient procedure for matching the input and output. The method has been extensively applied to coupler design for a wide variety of structures and to a study directed towards elimination of the surface field enhancement commonly experienced in coupler cells. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0008/0008201v1.pdf"}
{"id": "physics0012011", "abstract": "  Special relativity is reformulated as a symmetry property of space-time: Space-Time Exchange Invariance. The additional hypothesis of spatial homogeneity is then sufficient to derive the Lorentz transformation without reference to the traditional form of the Principle of Special Relativity. The kinematical version of the latter is shown to be a consequence of the Lorentz transformation. As a dynamical application, the laws of electrodynamics and magnetodynamics are derived from those of electrostatics and magnetostatics respectively. The 4-vector nature of the electromagnetic potential plays a crucial role in the last two derivations. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0012/0012011v2.pdf"}
{"id": "physics0105082", "abstract": "  We propose a unified approach to addition of some physical quantities (among which resistors and capacitors are the most well-known) that are usually encountered in introductory physics such that the formulae required to solve problems are always simply additive. This approach has the advantage of being consistent with the intuition of students. To demonstrate the effectiveness of our approach, we propose and solve several problems. We hope that this article can serve as a resource paper for problems on the subject. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0105/0105082v2.pdf"}
{"id": "physics0106006", "abstract": "  We present the applications of nonlinear local harmonic analysis methods to the modelling of beam-beam interaction. Our approach is based on methods provided the possibility to work with dynamical beam localization in phase space. The consideration of Fokker-Planck or Vlasov-Maxwell models is based on a number of anzatzes, which reduce initial problems to a number of dynamical systems (with constraints) and on variational-wavelet approach to polynomial/rational approximations for reduced nonlinear dynamics. We calculate contribution to full dynamics (partition function) from all underlying subscales via nonlinear eigenmodes decomposition. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0106/0106006v1.pdf"}
{"id": "physics0303003", "abstract": "  We report experimental results on the acceleration component probability distribution function at R_λ = 690 to probabilities of less than 10^-7. This is an improvement of more than an order of magnitude over past measurements and allows us to conclude that the fourth moment converges and the flatness is approximately 55. We compare our probability distribution to those predicted by several models inspired by non-extensive statistical mechanics. We also look at acceleration component probability distributions conditioned on a velocity component for conditioning velocities as high as 3 times the standard deviation and find them to be highly non-Gaussian. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0303/0303003v2.pdf"}
{"id": "physics0403068", "abstract": "  A novel imaging principle based on the interaction of electromagnetic waves with a beam of relativistic electrons is proposed. Wave-particle interaction is assumed to take place in a small spatial domain, so that each electron is only briefly accelerated by the incident field. In the one-dimensional case the spatial distribution of the source density can be directly observed in the temporal spectrum of the scattered field. Whereas, in the two-dimensional case the relation between the source and the spectrum is shown to be approximately the Radon transform. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0403/0403068v1.pdf"}
{"id": "physics0503100", "abstract": "  The electronic properties of squashed arm-chair carbon nanotubes are modeled using constraint free density functional tight binding molecular dynamics simulations. Independent from CNT diameter, squashing path can be divided into three regimes. In the first regime, the nanotube deforms with negligible force. In the second one, there is significantly more resistance to squashing with the force being ∼ 40-100 nN/per CNT unit cell. In the last regime, the CNT looses its hexagonal structure resulting in force drop-off followed by substantial force enhancement upon squashing. We compute the change in band-gap as a function of squashing and our main results are: (i) A band-gap initially opens due to interaction between atoms at the top and bottom sides of CNT. The π-orbital approximation is successful in modeling the band-gap opening at this stage. (ii) In the second regime of squashing, large π-σ interaction at the edges becomes important, which can lead to band-gap oscillation. (iii) Contrary to a common perception, nanotubes with broken mirror symmetry can have zero band-gap. (iv) All armchair nanotubes become metallic in the third regime of squashing. Finally, we discuss both differences and similarities obtained from the tight binding and density functional approaches. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0503/0503100v1.pdf"}
{"id": "physics0506197", "abstract": "  In this paper, we report high-precision absolute distance and vibration measurements performed with frequency scanned interferometry using a pair of single-mode optical fibers. Absolute distance was determined by counting the interference fringes produced while scanning the laser frequency. A high-finesse Fabry-Perot interferometer was used to determine frequency changes during scanning. Two multiple-distance-measurement analysis techniques were developed to improve distance precision and to extract the amplitude and frequency of vibrations. Under laboratory conditions, measurement precision of about 50 nm was achieved for absolute distances ranging from 0.1 meters to 0.7 meters by using the first multiple-distance-measurement technique. The second analysis technique has the capability to measure vibration frequencies ranging from 0.1 Hz to 100 Hz with amplitude as small as a few nanometers, without a priori knowledge. A possible optical alignment system for a silicon tracker is also presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0506/0506197v1.pdf"}
{"id": "physics0508039", "abstract": "  We consider a zero-surface-tension two-dimensional Hele-Shaw flow in an infinite wedge. There exists a self-similar interface evolution in this wedge, an analogue of the famous Saffman-Taylor finger in a channel, exact shape of which has been given by Kadanoff. One of the main features of this evolution is its infinite time of existence and stability for the Hadamard ill-posed problem. We derive several exact solutions existing infinitely by generalizing and perturbing the one by Kadanoff. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0508/0508039v1.pdf"}
{"id": "physics0509140", "abstract": "  The two-vibron dynamics associated to amide-I vibrations in a 3D α-helix is described according to a generalized Davydov model. The helix is modeled by three spines of hydrogen-bonded peptide units linked via covalent bonds. It is shown that the two-vibron energy spectrum supports both a two-vibron free states continuum and two kinds of bound states, called TVBS-I and TVBS-II, connected to the trapping of two vibrons onto the same amide-I mode and onto two nearest neighbor amide-I modes belonging to the same spine, respectively. At low temperature, non vanishing interspine hopping constants yield a three dimensional nature of both TVBS-I and TVBS-II which the wave functions extend over the three spines of the helix. At biological temperature, the pairs are confined in a given spine and exhibit the same features as the bound states described within a one-dimensional model. The interplay between the temperature and the 3D nature of the helix is also responsible for the occurrence of a third bound state called TVBS-III which refers to the trapping of two vibrons onto two different spines. The experimental signature of the existence of bound states is discussed through the simulation of their infrared pump-probe spectroscopic response. Finally, the fundamental question of the breather-like behavior of two-vibron bound states is addressed. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0509/0509140v1.pdf"}
{"id": "physics9801028", "abstract": "  We have simulated the temporal evolution of pressure due to capillary and viscous forces in two-phase drainage in porous media. We analyze our result in light of macroscopic flow equations for two-phase flow. We also investigate the effect of the trapped clusters on the pressure evolution and on the effective permeability of the system. We find that the capillary forces play an important role during the displacements for both fast and slow injection rates and both when the invading fluid is more or less viscous than the defending fluid. The simulations are based on a network simulator modeling two-phase drainage displacements on a two-dimensional lattice of tubes. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/9801/9801028v1.pdf"}
{"id": "q-bio0509023", "abstract": "  The study of Planktonic Foraminifera abundances permits to obtain climatic curves on the basis of percentage ratio between tropical and temperate/polar forms. Climatic changes were controlled by several phenomena as: (i) Milankovitch's cycles, produced by variations of astronomical parameters such as precession, obliquity and eccentricity; (ii) continental geodynamic evolution and orogenic belt; (iii) variations of atmospheric and oceanic currents; (iv) volcanic eruptions; (v) meteor impacts. But while astronomical parameters have a quasi-regular periodicity, the other phenomena can be considered as \"noise signal\" in natural systems. The interplay between cyclical astronomical variations, the \"noise signal\" and the intrinsic nonlinearity of the ecologic system produces strong glacial or interglacial period according to the stochastic resonance phenomenon. ", "pdf_url": "gs://arxiv-dataset/arxiv/q-bio/pdf/0509/0509023v1.pdf"}
{"id": "quant-ph0003136", "abstract": "  We consider quantum computing in the k-qubit model where the starting state of a quantum computer consists of k qubits in a pure state and n-k qubits in a maximally mixed state. We ask the following question: is there a general method for simulating an arbitrary m-qubit pure state quantum computation by a quantum computation in the k-qubit model? We show that, under certain constraints, this is impossible, unless m=O(k+ log n). ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0003/0003136v1.pdf"}
{"id": "quant-ph0302089", "abstract": "  We propose a tomographic approach to study quantum nonlocality in continuous variable quantum systems. On one hand we derive a Bell-like inequality for measured tomograms. On the other hand, we introduce pseudospin operators whose statistics can be inferred from the data characterizing the reconstructed state, thus giving the possibility to use standard Bell's inequalities. Illuminating examples are also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0302/0302089v2.pdf"}
{"id": "quant-ph0302184", "abstract": "  We discuss the role of boundary conditions in determining the physical content of the solutions of the Schrodinger equation. We study the standing-wave, the “in,” the “out,” and the purely outgoing boundary conditions. As well, we rephrase Feynman's +i ϵ prescription as a time-asymmetric, causal boundary condition, and discuss the connection of Feynman's +i ϵ prescription with the arrow of time of Quantum Electrodynamics. A parallel of this arrow of time with that of Classical Electrodynamics is made. We conclude that in general, the time evolution of a closed quantum system has indeed an arrow of time built into the propagators. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0302/0302184v1.pdf"}
{"id": "quant-ph0306185", "abstract": "  The notion of “radiating” and “non-radiating” current sources in classical electrodynamics plays an important role in calculations of direct and inverse electromagnetic scattering problems. Such a decomposition of the current is central for the notion of localized non-radiating electromagnetic modes. A completely quantum electrodynamic view is explored in this work. Photon emission and absorption current sources are classified as being either radiating or non-radiating. This quantum classification corresponds, respectively and exactly, to the notion of “real” and “virtual” photon processes. Causal properties of both real and virtual electromagnetic fields are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0306/0306185v1.pdf"}
{"id": "quant-ph0404073", "abstract": "  The surface impedance approach is discussed in connection with the precise calculation of the Casimir force between metallic plates. It allows to take into account the nonlocal connection between the current density and electric field inside of metals. In general, a material has to be described by two impedances Z_s(ω,q) and Z_p(ω,q) corresponding to two different polarization states. In contrast with the approximate Leontovich impedance they depend not only on frequency ω but also on the wave vector along the plate q. In this paper only the nonlocal effects happening at frequencies ω<ω_p (plasma frequency) are analyzed. We refer to all of them as the anomalous skin effect. The impedances are calculated for the propagating and evanescent fields in the Boltzmann approximation. It is found that Z_p significantly deviates from the local impedance as a result of the Thomas-Fermi screening. The nonlocal correction to the Casimir force is calculated at zero temperature. This correction is small but observable at small separations between bodies. The same theory can be used to find more significant nonlocal contribution at ω∼ω_p due to the plasmon excitation. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0404/0404073v1.pdf"}
{"id": "quant-ph0502047", "abstract": "  We consider travelling-wave parametric down-conversion in the high-gain regime and present the experimental demonstration of the quantum character of the spatial fluctuations in the system. In addition to showing the presence of sub-shot noise fluctuations in the intensity difference, we demonstrate that the peak value of the normalized spatial correlations between signal and idler lies well above the line marking the boundary between the classical and the quantum domain. This effect is equivalent to the apparent violation of the Cauchy-Schwartz inequality, predicted by some of us years ago, which represents a spatial analogue of photon antibunching in time. Finally, we analyse numerically the transition from the quantum to the classical regime when the gain is increased and we emphasize the role of the inaccuracy in the determination of the symmetry center of the signal/idler pattern in the far-field plane. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0502/0502047v1.pdf"}
{"id": "quant-ph0602134", "abstract": "  We develop a circuit theory that enables us to analyze quantum measurements on a two-level system and on a continuous-variable system on an equal footing. As a measurement scheme applicable to both systems, we discuss a swapping state measurement which exchanges quantum states between the system and the measuring apparatus before the apparatus meter is read out. This swapping state measurement has an advantage in gravitational-wave detection over contractive state measurement in that the postmeasurement state of the system can be set to a prescribed one, regardless of the outcome of the measurement. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0602/0602134v2.pdf"}
{"id": "quant-ph0606049", "abstract": "  We analyze a cryptographic protocol for generating a distributed secret key from correlations that violate a Bell inequality by a sufficient amount, and prove its security against eavesdroppers, constrained only by the assumption that any information accessible to them must be compatible with the non-signaling principle. The claim holds with respect to the state-of-the-art security definition used in cryptography, known as universally-composable security. The non-signaling assumption only refers to the statistics of measurement outcomes depending on the choices of measurements; hence security is independent of the internal workings of the devices — they do not even need to follow the laws of quantum theory. This is relevant for practice as a correct and complete modeling of realistic devices is generally impossible. The techniques developed are general and can be applied to other Bell inequality-based protocols. In particular, we provide a scheme for estimating Bell-inequality violations when the samples are not independent and identically distributed. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0606/0606049v5.pdf"}
{"id": "quant-ph0607060", "abstract": "  We propose a scalable approach to building cluster states of matter qubits using coherent states of light. Recent work on the subject relies on the use of single photonic qubits in the measurement process. These schemes can be made robust to detector loss, spontaneous emission and cavity mismatching but as a consequence the overhead costs grow rapidly, in particular when considering single photon loss. In contrast, our approach uses continuous variables and highly efficient homodyne measurements. We present a two-qubit scheme, with a simple bucket measurement system yielding an entangling operation with success probability 1/2. Then we extend this to a three-qubit interaction, increasing this probability to 3/4. We discuss the important issues of the overhead cost and the time scaling. This leads to a \"no-measurement\" approach to building cluster states, making use of geometric phases in phase space. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0607/0607060v2.pdf"}
{"id": "0704.0045", "abstract": "  This paper considers the propagation of shallow-water solitary and nonlinear periodic waves over a gradual slope with bottom friction in the framework of a variable-coefficient Korteweg-de Vries equation. We use the Whitham averaging method, using a recent development of this theory for perturbed integrable equations. This general approach enables us not only to improve known results on the adiabatic evolution of isolated solitary waves and periodic wave trains in the presence of variable topography and bottom friction, modeled by the Chezy law, but also importantly, to study the effects of these factors on the propagation of undular bores, which are essentially unsteady in the system under consideration. In particular, it is shown that the combined action of variable topography and bottom friction generally imposes certain global restrictions on the undular bore propagation so that the evolution of the leading solitary wave can be substantially different from that of an isolated solitary wave with the same initial amplitude. This non-local effect is due to nonlinear wave interactions within the undular bore and can lead to an additional solitary wave amplitude growth, which cannot be predicted in the framework of the traditional adiabatic approach to the propagation of solitary waves in slowly varying media. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.0045v1.pdf"}
{"id": "0704.2589", "abstract": "  Multiwavelength observations are reported here of the Be/X-ray binary pulsar system GRO J1008-57. Over ten years worth of data are gathered together to show that the periodic X-ray outbursts are dependant on both the binary motion and the size of the circumstellar disk. In the first instance an accurate orbital solution is determined from pulse periods, and in the second case the strength and shape of the Halpha emission line is shown to be a valuable indicator of disk size and its behaviour. Furthermore, the shape of the emission line permits a direct determination of the disk size which is in good agreement with theoretical estimates. A detailed study of the pulse period variations during outbursts determined the binary period to be 247.8, in good agreement with the period determined from the recurrence of the outbursts. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.2589v1.pdf"}
{"id": "0705.0084", "abstract": "  We investigate the gravitational wake due to, and dynamical friction on, a perturber moving on a circular orbit in a uniform gaseous medium using a semi-analytic method. This work is a straightforward extension of Ostriker (1999) who studied the case of a straight-line trajectory. The circular orbit causes the bending of the wake in the background medium along the orbit, forming a long trailing tail. The wake distribution is thus asymmetric, giving rise to the drag forces in both opposite (azimuthal) and lateral (radial) directions to the motion of the perturber, although the latter does not contribute to orbital decay much. For subsonic motion, the density wake with a weak tail is simply a curved version of that in Ostriker and does not exhibit the front-back symmetry. The resulting drag force in the opposite direction is remarkably similar to the finite-time, linear-trajectory counterpart. On the other hand, a supersonic perturber is able to overtake its own wake, possibly multiple times, and develops a very pronounced tail. The supersonic tail surrounds the perturber in a trailing spiral fashion, enhancing the perturbed density at the back as well as far front of the perturber. We provide the fitting formulae for the drag forces as functions of the Mach number, whose azimuthal part is surprisingly in good agreement with the Ostriker's formula, provided Vp t=2 Rp, where Vp and Rp are the velocity and orbital radius of the perturber, respectively. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.0084v1.pdf"}
{"id": "0705.2311", "abstract": "  In the classical one-dimensional solution of fluid dynamics equations all unknown functions depend only on time t and Cartesian coordinate x. Although fluid spreads in all directions (velocity vector has three components) the whole picture of motion is relatively simple: trajectory of one fluid particle from plane x=const completely determines motion of the whole plane. Basing on the symmetry analysis of differential equations we propose generalization of this solution allowing movements in different directions of fluid particles belonging to plane x=const. At that, all functions but an angle determining the direction of particle's motion depend on t and x only, whereas the angle depends on all coordinates. In this solution the whole picture of motion superposes from identical trajectories placed under different angles in 3D space. Orientations of the trajectories are restricted by a finite relation possessing functional arbitrariness. The solution describes three-dimensional nonlinear processes and singularities in infinitely conducting plasma, gas or incompressible liquid. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.2311v1.pdf"}
{"id": "0705.2316", "abstract": "  An explanation of the recently discovered 7 s pulsations from the isolated neutron star RX J1856.5-3754 is presented. It is assumed that the real spin period of this source is ≈1 s, whereas the observed spin-modulation is caused by the presence of a nearly transverse, very low frequency drift waves in the pulsar magnetosphere. It is supposed that the period of the drift wave is equal to a recently observed one. The simulated lightcurve is plotted, the angular parameters are defined and the value of the pulsed fraction of only ∼ 1.2", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.2316v1.pdf"}
{"id": "0705.2779", "abstract": "  A new catalogue of extended radio sources has been prepared based on arcminute-resolution 1420 MHz images from the Canadian Galactic Plane Survey (CGPS). The new catalogue provides both 1420 MHz and 408 MHz flux density measurements on sources found near the Galactic plane in the second quadrant of our Galaxy. In addition cross-identifications are made with other major radio catalogues and information is provided to facilitate the recovery of CGPS image data associated with each catalogued source. Numerous new radio sources are identified and the catalogue provides a comprehensive summary of both newly discovered and previously known HII regions and supernova remnants in the outer Galaxy. The catalogue should be of use both for synoptic studies of Galactic structure and for placing higher resolution observations, at radio and other wavelengths, in context. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.2779v1.pdf"}
{"id": "0705.3745", "abstract": "  It is shown that the action associated with center vortices in SU(2) lattice gauge theory is strongly correlated with extrinsic and internal curvatures of the vortex surface and that this correlation persists in the continuum limit. Thus a good approximation for the effective vortex action is the action of rigid strings, which can reproduce some of the observed geometric properties of center vortices. It is conjectured that rigidity may be induced by some fields localized on vortices, and a model-independent test of localization is performed. Monopoles detected in the Abelian projection are discussed as natural candidates for such two-dimensional fields. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.3745v2.pdf"}
{"id": "0706.2973", "abstract": "  At non-equilibrium phase transitions into absorbing (trapped) states, it is well known that the directed percolation (DP) critical scaling is shared by two classes of models with a single (S) absorbing state and with infinitely many (IM) absorbing states. We study the crossover behavior in one dimension, arising from a considerable reduction of the number of absorbing states (typically from the IM-type to the S-type DP models), by following two different (excitatory or inhibitory) routes which make the auxiliary field density abruptly jump at the crossover. Along the excitatory route, the system becomes overly activated even for an infinitesimal perturbation and its crossover becomes discontinuous. Along the inhibitory route, we find continuous crossover with the universal crossover exponent ϕ≃ 1.78(6), which is argued to be equal to ν_, the relaxation time exponent of the DP universality class on a general footing. This conjecture is also confirmed in the case of the directed Ising (parity-conserving) class. Finally, we discuss the effect of diffusion to the IM-type models and suggest an argument why diffusive models with some hybrid-type reactions should belong to the DP class. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0706/0706.2973v1.pdf"}
{"id": "0707.2861", "abstract": "  We investigate bright matter-wave solitons in the presence of a spatially varying nonlinearity. It is demonstrated that a translation mode is excited due to the spatial inhomogeneity and its frequency is derived analytically and also studied numerically. Both cases of purely one-dimensional and “cigar-shaped” condensates are studied by means of different mean-field models, and the oscillation frequencies of the pertinent solitons are found and compared with the results obtained by the linear stability analysis.Numerical results are shown to be in very good agreement with the corresponding analytical predictions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0707/0707.2861v1.pdf"}
{"id": "0707.3527", "abstract": "  We present preliminary results of a study of the low frequency radio continuum emission from the nuclei of Giant Low Surface Brightness (LSB) galaxies. We have mapped the emission and searched for extended features such as radio lobes/jets associated with AGN activity. LSB galaxies are poor in star formation and generally less evolved compared to nearby bright spirals. This paper presents low frequency observations of 3 galaxies; PGC 045080 at 1.4 GHz, 610 MHz, 325MHz, UGC 1922 at 610 MHz and UGC 6614 at 610 MHz. The observations were done with the GMRT. Radio cores as well as extended structures were detected and mapped in all three galaxies; the extended emission may be assocated with jets/lobes associated with AGN activity. Our results indicate that although these galaxies are optically dim, their nuclei can host AGN that are bright in the radio domain. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0707/0707.3527v1.pdf"}
{"id": "0708.1110", "abstract": "  We report the discovery of an episode of coherent millisecond X-ray pulsation in the neutron star low-mass X-ray binary Aql X-1. The episode lasts for slightly more than 150 seconds, during which the pulse frequency is consistent with being constant. No X-ray burst or other evidence of thermonuclear burning activity is seen in correspondence with the pulsation, which can thus be identified as occurring in the persistent emission. The pulsation frequency is 550.27 Hz, very close (0.5 Hz higher) to the maximum reported frequency from burst oscillations in this source. Hence we identify this frequency with the neutron star spin frequency. The pulsed fraction is strongly energy dependent, ranging from <1", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0708/0708.1110v2.pdf"}
{"id": "0709.0665", "abstract": "  Multiplicity distributions of hadrons produced in central nucleus-nucleus collisions are studied within the hadron-resonance gas model in the large volume limit. In the canonical ensemble conservation of three charges (baryon number, electric charge, and strangeness) is enforced. In addition, in the micro-canonical ensemble energy conservation is included. An analytical method is used to account for resonance decays. Multiplicity distributions and scaled variances for negatively charged hadrons are presented along the chemical freeze-out line of central Pb+Pb (Au+Au) collisions from SIS to LHC energies. Predictions obtained within different statistical ensembles are compared with preliminary NA49 experimental results on central Pb+Pb collisions in the SPS energy range. The measured fluctuations are significantly narrower than a Poisson reference distribution, and clearly favor expectations for the micro-canonical ensemble. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0709/0709.0665v1.pdf"}
{"id": "0709.1065", "abstract": "  We report on phonon properties and electronic transitions in CaCu3Ti4O12, a material which reveals a colossal dielectric constant at room temperature without any ferroelectric transition. The results of far- and mid-infrared measurements are compared to those obtained by broadband dielectric and millimeter-wave spectroscopy on the same single crystal. The unusual temperature dependence of phonon eigenfrequencies, dampings and ionic plasma frequencies of low lying phonon modes are analyzed and discussed in detail. Electronic excitations below 4 eV are identified as transitions between full and empty hybridized oxygen-copper bands and between oxygen-copper and unoccupied Ti 3d bands. The unusually small band gap determined from the dc-conductivity ( 200 meV) compares well with the optical results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0709/0709.1065v1.pdf"}
{"id": "0709.1237", "abstract": "  We investigate transition rates between different spin configurations for S ≥ 1 spins weakly coupled to a d-dimensional phonon bath. This study is motivated by understanding observed magnetization relaxation as a function of temperature in diverse magnetic systems such as arrays of magnetic nanoparticles and magnetic molecules. We assume that the magnetization of the spin system relaxes through consecutive emission or absorption of a single phonon. From a weak, linear spin-phonon coupling Hamiltonian, we derive transition rates that would be used to examine dynamic properties of the system in kinetic Monte Carlo simulations. Although the derived phonon-assisted transition rates satisfy detailed balance, in the case of two and three dimensional phonon baths, transitions between degenerate states are not allowed. Thus, if there are no alternative paths along which the spin system can relax, the relaxation time diverges. Otherwise, the system finds other paths, which leads to an increase in the relaxation time and energy barrier. However, when higher-order phonon processes are included in the transition rates, it is found that the system can reach the states which were inaccessible due to the forbidden transitions. As a result, the system recovers some of the dynamic properties obtained using the Glauber transition rate. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0709/0709.1237v1.pdf"}
{"id": "0709.1339", "abstract": "  Feedback control (based on the quantum continuous measurement) of quantum systems inevitably suffers from estimation delays. In this paper we give a delay-dependent stability criterion for a wide class of nonlinear stochastic systems including quantum spin systems. We utilize a semi-algebraic problem approach to incorporate the structure of density matrices. To show the effectiveness of the result, we derive a globally stabilizing control law for a quantum spin-1/2 systems in the face of feedback delays. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0709/0709.1339v2.pdf"}
{"id": "0709.2674", "abstract": "  We present images and light curves of the bipolar Planetary Nebula RPJ 053059-683542 that was discovered in the Reid-Parker AAO/UKST H-alpha survey of the Large Magellanic Cloud (LMC). The emission from this object appears entirely nebular, with the central star apparently obscured by a central band of absorption that bisects the nebula. The light curves, which were derived from images from the SuperMACHO project at CTIO, showed significant, spatially resolved variability over the period 2002 January through 2005 December. Remarkably, the emission from the two bright lobes of the nebula vary either independently, or similarly but with a phase lag of at least one year. The optical spectra show a low level of nebular excitation, and only modest N enrichment. Infrared photometry from the 2MASS and SAGE surveys indicates the presence of a significant quantity of dust. The available data imply that the central star has a close binary companion, and that the system has undergone some kind of outburst event that caused the nebular emission to first brighten and then fade. Further monitoring, high-resolution imaging, and detailed IR polarimetry and spectroscopy would uncover the nature of this nebula and the unseen ionizing source. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0709/0709.2674v1.pdf"}
{"id": "0710.1770", "abstract": "  While masers in the 1720 MHz transition of OH are detected toward many supernova remnants (SNRs), no other OH transition is seen as a maser in SNRs. We present a search for masers at 6049 MHz, which has recently been predicted to produce masers by pure collisional excitation at conditions similar to that required for 1720 MHz masing. The Effelsberg 100 m telescope was used to observe the excited-state 6016, 6030, 6035, and 6049 MHz lines of OH toward selected SNRs, most of which have previously-detected bright 1720 MHz masers. No excited-state masers are found toward SNRs, consistent with previous observations of the 6049 MHz and other excited-state transitions. We do not see clear evidence of absorption toward SNR target positions, although we do see evidence of absorption in the molecular cloud at +50 km/s near Sgr A East. Weak absorption is detected at 6016 MHz toward W3(OH), while stronger, narrower emission is seen at 6049 MHz, suggesting that the 6049 MHz emission is a low-gain maser. We conclude that conditions in SNRs are not conducive to excited-state maser emission, especially in excited-state satellite lines. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.1770v1.pdf"}
{"id": "0710.2208", "abstract": "  For a generic distribution of rank two on a manifold M of dimension five, we introduce the notion of a generalized contact form. To such a form we associate a generalized Reeb field and a partial connection. From these data, we explicitly constructed a pseudo–Riemannian metric on M of split signature. We prove that a change of the generalized contact form only leads to a conformal rescaling of this metric, so the corresponding conformal class is intrinsic to the distribution. In the second part of the article, we relate this conformal class to the canonical Cartan connection associated to the distribution. This is used to prove that it coincides with the conformal class constructed by Nurowski. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.2208v1.pdf"}
{"id": "0710.2515", "abstract": "  In this paper we present a 5-parametric family of static asymptotically flat solutions for the superposed gravitational and electromagnetic fields of two Reissner-Nordström sources with arbitrary parameters – masses, charges and separating distance. A procedure for solving of the linear singular integral equation form of the electrovacuum Einstein - Maxwell equations for stationary axisymmetric fields is described in detail. The 4-parametric family of equilibrium configurations of two Reissner-Nordström sources (one of which should be a black hole and another one – a naked singularity) presented in our recent paper <cit.> arises after a restriction of the parameters of the 5-parametric solution presented here by the equilibrium condition which provides the absence in the solution of conical points on the symmetry axis between the sources. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.2515v1.pdf"}
{"id": "0710.2902", "abstract": "  We report on our initial analysis of a deep 510 ks observation of the Galactic oxygen-rich supernova remnant (SNR) G292.0+1.8 with the Chandra X-ray Observatory. Our new Chandra ACIS-I observation has a larger field of view and an order of magnitude deeper exposure than the previous Chandra observation, which allows us to cover the entire SNR and to detect new metal-rich ejecta features. We find a highly non-uniform distribution of thermodynamic conditions of the X-ray emitting hot gas that correlates well with the optical [O III] emission, suggesting the possibility that the originating supernova explosion of G292.0+1.8 was itself asymmetric. We also reveal spectacular substructures of a torus, a jet, and an extended central compact nebula all associated with the embedded pulsar J1124-5916. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.2902v1.pdf"}
{"id": "0710.3286", "abstract": "  The migration of a suspended vesicle in an unbounded Poiseuille flow is investigated numerically in the low Reynolds number limit. We consider the situation without viscosity contrast between the interior of the vesicle and the exterior. Using the boundary integral method we solve the corresponding hydrodynamic flow equations and track explicitly the vesicle dynamics in two dimensions. We find that the interplay between the nonlinear character of the Poiseuille flow and the vesicle deformation causes a cross-streamline migration of vesicles towards the center of the Poiseuille flow. This is in a marked contrast with a result [L.G. Leal, Ann. Rev. Fluid Mech. 12, 435(1980)]according to which the droplet moves away from the center (provided there is no viscosity contrast between the internal and the external fluids). The migration velocity is found to increase with the local capillary number (defined by the time scale of the vesicle relaxation towards its equilibrium shape times the local shear rate), but reaches a plateau above a certain value of the capillary number. This plateau value increases with the curvature of the parabolic flow profile. We present scaling laws for the migration velocity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.3286v1.pdf"}
{"id": "0710.4770", "abstract": "  The study of nanospintronic devices utilizing coherent transport through molecular scale multiply-connected geometries in the presence of moderate magnetic fields is presented. It is shown how two types of simple devices, spin filters and spin splitters (or Stern-Gerlach devices) may be constructed from molecular nanometric rings utilizing the Aharonov-Bohm effect. The current is calculated within a single electron approximation and within a many-body master equation approach where charging effects are accounted for in the Coulomb Blockade regime. We provide rules and tools to develop and analyze efficient spintronic devices based on nanometric interferometers. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.4770v1.pdf"}
{"id": "0710.5439", "abstract": "  Nonequilibrium steady states in an open system connecting two reservoirs of platelike colloidal particles are investigated by means of a recently proposed phenomenological dynamic density functional theory [M. Bier and R. van Roij, Phys. Rev. E 76, 021405 (2007)]. The platelike colloidal particles are approximated within the Zwanzig model of restricted orientations, which exhibits an isotropic-nematic bulk phase transition. Inhomogeneities of the local chemical potential generate a diffusion current which relaxes to a nonvanishing value if the two reservoirs coupled to the system sustain different chemical potentials. The relaxation process of initial states towards the steady state turns out to comprise two regimes: a smoothening of initial steplike structures followed by an ultimate relaxation of the slowest diffusive mode. The position of a nonequilibrium interface and the particle current of steady states depend nontrivially on the structure of the reservoirs due to the coupling between translational and orientational degrees of freedom of the fluid. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.5439v1.pdf"}
{"id": "0710.5921", "abstract": "  Motivated by recent experiments on Faraday waves in Bose-Einstein condensates we investigate both analytically and numerically the dynamics of cigar-shaped Bose-condensed gases subject to periodic modulation of the strength of the transverse confinement. We offer a fully analytical explanation of the observed parametric resonance, based on a Mathieu-type analysis of the non-polynomial Schrödinger equation. The theoretical prediction for the pattern periodicity versus the driving frequency is directly compared with the experimental data, yielding good qualitative and quantitative agreement between the two. These results are corroborated by direct numerical simulations of both the one-dimensional non-polynomial Schrödinger equation and of the fully three-dimensional Gross-Pitaevskii equation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.5921v1.pdf"}
{"id": "0711.0564", "abstract": "  We present a new computational framework (LEO), that enables us to carry out the very first large-scale, high-resolution computations in the context of the characteristic approach in numerical relativity. At the analytic level, our approach is based on a new implementation of the “eth” formalism, using a non-standard representation of the spin-raising and lowering angular operators in terms of non-conformal coordinates on the sphere; we couple this formalism to a partially first-order reduction (in the angular variables) of the Einstein equations. The numerical implementation of our approach supplies the basic building blocks for a highly parallel, easily extensible numerical code. We demonstrate the adaptability and excellent scaling of our numerical code by solving, within our numerical framework, for a scalar field minimally coupled to gravity (the Einstein-Klein-Gordon problem) in 3-dimensions. The nonlinear code is globally second-order convergent, and has been extensively tested using as reference a calibrated code with the same boundary-initial data and radial marching algorithm. In this context, we show how accurately we can follow quasi-normal mode ringing. In the linear regime, we show energy conservation for a number of initial data sets with varying angular structure. A striking result that arises in this context is the saturation of the flow of energy through the Schwarzschild radius. As a final calibration check we perform a large simulation with resolution never achieved before. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.0564v1.pdf"}
{"id": "0711.4495", "abstract": "  We revisit the scaling properties of a model for non-equilibrium wetting [Phys. Rev. Lett. 79, 2710 (1997)], correcting previous estimates of the critical exponents and providing a complete scaling scheme. Moreover, we investigate a special point in the phase diagram, where the model exhibits a roughening transition related to directed percolation. We argue that in the vicinity of this point evaporation from the middle of plateaus can be interpreted as an external field in the language of directed percolation. This analogy allows us to compute the crossover exponent and to predict the form of the phase transition line close to its terminal point. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.4495v1.pdf"}
{"id": "0801.0453", "abstract": "  We discuss the flavor of leading jet partons as a valuable probe of nuclear matter. We point out that the coupling of jets to nuclear matter naturally leads to an alteration of jet chemistry even at high transverse momentum p_T. In particular, QCD jets coupling to a chemically equilibrated quark gluon plasma in nuclear collisions, will lead to hadron ratios at high transverse momentum p_T that can differ significantly from their counterparts in p+p collisions. Flavor measurements could complement energy loss as a way to study interactions of hard QCD jets with nuclear matter. Roughly speaking they probe the inverse mean free path 1/λ, while energy loss probes the average squared momentum transfer μ^2/λ. We present some estimates for the rate of jet conversions in a consistent Fokker-Planck framework and their impact on future high-p_T identified hadron measurements at RHIC and LHC. We also suggest some novel observables to test flavor effects. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.0453v2.pdf"}
{"id": "0801.4535", "abstract": "  We derive the SZ effect arising in radio-galaxy lobes that are filled with high-energy, non-thermal electrons. We provide here quantitative estimates for SZ effect expected from the radio galaxy lobes by normalizing it to the Inverse-Compton light, observed in the X-ray band, as produced by the extrapolation to low energies of the radio emitting electron spectrum in these radio lobes. We compute the spectral and spatial characteristics of the SZ effect associated to the radio lobes of two distant radio galaxies (3C294 and 3C432) recently observed by Chandra, and we further discuss its detectability with the next generation microwave and sub-mm experiments with arcsec and ∼μK sensitivity. We finally highlight the potential use of the SZE from radio-galaxy lobes in the astrophysical and cosmological context. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.4535v1.pdf"}
{"id": "0802.2179", "abstract": "  We investigate colors and mass-to-light ratios (M/Ls) of the bulges and disks for 28 nearby spiral galaxies with various morphological types of Sab to Scd, using images in optical and near-infrared (V, I, and J) bands and published rotation curves. It is shown that the observed colors and M/Ls generally agree with the galaxy formation model with an exponentially declining star formation rate and shallow slope (ex. Scalo) initial mass function (IMF) for both the bulges and the disks. We find that the bulge M/L is generally higher than the disk M/L and that the galaxies with larger bulge-to-total luminosity ratio tend to have a smaller bulge M/L. The fact indicates that the luminosity-weighted average age of bulges for early-type spirals is younger than that of later-type spirals. These results support a formation scenario that produces young stars for the bulges of middle-type and early-type spirals. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.2179v1.pdf"}
{"id": "0802.3950", "abstract": "  We discuss a generic model of Bayesian inference with binary variables defined on edges of a planar graph. The Loop Calculus approach of [1, 2] is used to evaluate the resulting series expansion for the partition function. We show that, for planar graphs, truncating the series at single-connected loops reduces, via a map reminiscent of the Fisher transformation [3], to evaluating the partition function of the dimer matching model on an auxiliary planar graph. Thus, the truncated series can be easily re-summed, using the Pfaffian formula of Kasteleyn [4]. This allows to identify a big class of computationally tractable planar models reducible to a dimer model via the Belief Propagation (gauge) transformation. The Pfaffian representation can also be extended to the full Loop Series, in which case the expansion becomes a sum of Pfaffian contributions, each associated with dimer matchings on an extension to a subgraph of the original graph. Algorithmic consequences of the Pfaffian representation, as well as relations to quantum and non-planar models, are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.3950v2.pdf"}
{"id": "0802.4065", "abstract": "  Building on general formulas obtained from the approximate renormalized effective action, the stress-energy tensor of the quantized massive spinor and vector fields in the spacetime of the regular black hole is constructed. Such a black hole is the solution to the coupled system of nonlinear electrodynamics and general relativity. A detailed analytical and numerical analysis of the stress-energy tensor in the exterior region is presented. It is shown that for small values of the charge as well as large distances from the black hole the leading behavior of the stress-energy tensor is similar to that in the Reissner-Nordström geometry. Important differences appear when the inner horizon becomes close to the event horizon. A special emphasis is put on the extremal configuration and it is shown that the stress-energy tensor is regular inside the event horizon of the extremal black hole. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.4065v1.pdf"}
{"id": "0803.0314", "abstract": "  We quantitatively address whether IceCube, a kilometer-scale neutrino detector under construction at the South Pole, can observe neutrinos pointing back at the accelerators of the Galactic cosmic rays. The photon flux from candidate sources identified by the Milagro detector in a survey of the TeV sky is consistent with the flux expected from a typical cosmic-ray generating supernova remnant interacting with the interstellar medium. We show here that IceCube can provide incontrovertible evidence of cosmic-ray acceleration in these sources by detecting neutrinos. We find that the signal is optimally identified by specializing to events with energies above 30 TeV where the atmospheric neutrino background is low. We conclude that evidence for a correlation between the Milagro and IceCube sky maps should be conclusive after several years. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0803/0803.0314v2.pdf"}
{"id": "0803.1706", "abstract": "  The distribution of recurrence times or return intervals between extreme events is important to characterize and understand the behavior of physical systems and phenomena in many disciplines. It is well known that many physical processes in nature and society display long range correlations. Hence, in the last few years, considerable research effort has been directed towards studying the distribution of return intervals for long range correlated time series. Based on numerical simulations, it was shown that the return interval distributions are of stretched exponential type. In this paper, we obtain an analytical expression for the distribution of return intervals in long range correlated time series which holds good when the average return intervals are large. We show that the distribution is actually a product of power law and a stretched exponential form. We also discuss the regimes of validity and perform detailed studies on how the return interval distribution depends on the threshold used to define extreme events. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0803/0803.1706v1.pdf"}
{"id": "0803.2875", "abstract": "  We investigate a reversible polymerization process in which individual polymers aggregate and fragment at a rate proportional to their molecular weight. We find a nonequilibrium phase transition despite the fact that the dynamics are perfectly reversible. When the strength of the fragmentation process exceeds a critical threshold, the system reaches a thermodynamic steady state where the total number of polymers is proportional to the system size. The polymer length distribution has a sharp exponential tail in this case. When the strength of the fragmentation process falls below the critical threshold, the steady state becomes non-thermodynamic as the total number of polymers grows sub-linearly with the system size. Moreover, the length distribution has an algebraic tail and the characteristic exponent varies continuously with the fragmentation rate. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0803/0803.2875v1.pdf"}
{"id": "0804.3870", "abstract": "  Three Algol-type binaries in Cygnus constellation were selected for an analysis from a huge database of observations made by the INTEGRAL/OMC camera. These data were processed and analyzed, resulting in a first light-curve study of these neglected eclipsing binaries. The temperatures of the primary components range from 9500 K to 10500 K and the inclinations are circa 73deg (for PV Cyg and V1011 Cyg), while almost 90deg for V822 Cyg. All of them seem to be main-sequence stars, well within their critical Roche lobes. Nevertheless, further detailed analyses are still needed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0804/0804.3870v1.pdf"}
{"id": "0806.0760", "abstract": "  We study the behavior of fluids, confined by geometrically structured substrates, upon approaching a critical point at T = Tc in their bulk phase diagram. As generic substrate structures periodic arrays of wedges and ridges are considered. Based on general renormalization group arguments we calculate, within mean field approximation, the universal scaling functions for order parameter profiles of a fluid close to a single structured substrate and discuss the decay of its spatial variation into the bulk. We compare the excess adsorption at corrugated substrates with the one at planar walls. The confinement of a critical fluid by two walls generates effective critical Casimir forces between them. We calculate corresponding universal scaling functions for the normal critical Casimir force between a flat and a geometrically structured substrate as well as the lateral critical Casimir force between two identically patterned substrates. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0806/0806.0760v2.pdf"}
{"id": "0806.1045", "abstract": "  Molecular clouds are observed to be turbulent, but the origin of this turbulence is not well understood. As a result, there are two different approaches to simulating molecular clouds, one in which the turbulence is allowed to decay after it is initialized, and one in which it is driven. We use the adaptive mesh refinement (AMR) code, Orion, to perform high-resolution simulations of molecular cloud cores and protostars in environments with both driven and decaying turbulence. We include self-gravity, use a barotropic equation of state, and represent regions exceeding the maximum grid resolution with sink particles. We analyze the properties of bound cores such as size, shape, linewidth, and rotational energy, and we find reasonable agreement with observation. At high resolution, the different rates of core accretion in the two cases have a significant effect on protostellar system development. Clumps forming in a decaying turbulence environment produce high-multiplicity protostellar systems with Toomre-Q unstable disks that exhibit characteristics of the competitive accretion model for star formation. In contrast, cores forming in the context of continuously driven turbulence and virial equilibrium form smaller protostellar systems with fewer low-mass members. Our simulations of driven and decaying turbulence show some statistically significant differences, particularly in the production of brown dwarfs and core rotation, but the uncertainties are large enough that we are not able to conclude whether observations favor one or the other. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0806/0806.1045v1.pdf"}
{"id": "0806.3484", "abstract": "  We study the connections between link invariants, the chromatic polynomial, geometric representations of models of statistical mechanics, and their common underlying algebraic structure. We establish a relation between several algebras and their associated combinatorial and topological quantities. In particular, we define the chromatic algebra, whose Markov trace is the chromatic polynomial χ_Q of an associated graph, and we give applications of this new algebraic approach to the combinatorial properties of the chromatic polynomial. In statistical mechanics, this algebra occurs in the low temperature expansion of the Q-state Potts model. We establish a relationship between the chromatic algebra and the SO(3) Birman-Murakami-Wenzl algebra, which is an algebra-level analogue of the correspondence between the SO(3) Kauffman polynomial and the chromatic polynomial. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0806/0806.3484v3.pdf"}
{"id": "0806.4614", "abstract": "  We introduce new black hole solutions to the Einstein-Yang-Mills-Born-Infeld (EYMBI), Einstein-Yang-Mills-Born-Infeld-Gauss-Bonnet (EYMBIGB) and Einstein-Yang-Mills-Born-Infeld-Gauss-Bonnet-Lovelock (EYMBIGBL) gravities in higher dimensions N≥ 5 to investigate the roles of Born-Infeld parameter β. It is shown that, these solutions in the limits of β→ 0, and β→∞ , represent pure gravity and gravity coupled with Yang-Mills fields, respectively. For 0<β <∞ it yields a variety of black holes, supporting even regular ones at r=0. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0806/0806.4614v2.pdf"}
{"id": "0807.0665", "abstract": "  The interior of a Schwarzschild black hole is investigated at the level of phenomenological dynamics with the discreteness corrections of loop quantum geometry implemented in two different improved quantization schemes. In one scheme, the classical black hole singularity is resolved by the quantum bounce, which bridges the black hole interior with a white hole interior. In the other scheme, the classical singularity is resolved and the event horizon is also diffused by the quantum bounce. Jumping over the quantum bounce, the black hole gives birth to a baby black hole with a much smaller mass. This lineage continues as each classical black hole brings forth its own descendant in the consecutive classical cycle, giving the whole extended spacetime fractal structure, until the solution eventually descends into deep Planck regime, signaling a breakdown of the semiclassical description. The issues of scaling symmetry and no-hair theorem are also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.0665v2.pdf"}
{"id": "0807.1050", "abstract": "  An effect of the dynamic gain saturation on chirped-pulse oscillator was investigated. It was found, that the dynamic gain saturation causes strong perturbations of the pulse front that destabilizes an oscillator. As a result, the chirped-pulse exists only within some limited range of dispersions and there is a limit of energy growth for a given resonator period. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.1050v1.pdf"}
{"id": "0807.2921", "abstract": "  The determination of the conductivity of a deterministic or stochastic classical system coupled to reservoirs at its ends can in general be mapped onto the problem of computing the stiffness (the `energy' cost of twisting the boundaries) of a quantum-like operator. The nature of the coupling to the reservoirs determines the details of the mechanical coupling of the torque at the ends. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.2921v2.pdf"}
{"id": "0807.3486", "abstract": "  Some years ago Gribov developed the so-called supercritical light quark confinement scenario. Based on physical arguments he conjectured a drastic change in the analytical properties of the quark propagator when the back-reaction of Goldstone bosons (pions) is considered. We investigate this scenario and provide numerical solutions for the quark propagator in the complex plane with and without the pion back-reaction. We find no evidence for the scenario Gribov advocated. As an aside we present a novel method to solve the quark Dyson-Schwinger equation in the complex plane and discuss new characteristics of dynamical chiral symmetry breaking in our truncation scheme. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.3486v2.pdf"}
{"id": "0807.4029", "abstract": "  The dc conductance of normal-superconducting hybrid structures is discussed. It is shown that since the Bogoliubov-DeGennes (BDG) equation does not conserve charge, its application to create a Landauer-type approach for the conductance of the NSN system is problematic. We `mend' this deficiency by calculating the conductance from the Kubo formula for a ring configuration (for this geometry the solutions of the BDG equation conserve charge). We show that the presence of a superconductor segment within an otherwise normal metal may reduce the overall conductance of the composite structure. This reduction enhances the tendency of the NS composite to become insulating. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.4029v1.pdf"}
{"id": "0807.4264", "abstract": "  Hydrogen-helium mixtures at conditions of Jupiter's interior are studied with first-principles computer simulations. The resulting equation of state (EOS) implies that Jupiter possesses a central core of 14-18 Earth masses of heavier elements, a result that supports core accretion as standard model for the formation of hydrogen-rich giant planets. Our nominal model has about 2 Earth masses of planetary ices in the H-He-rich mantle, a result that is, within modeling errors, consistent with abundances measured by the 1995 Galileo Entry Probe mission (equivalent to about 5 Earth masses of planetary ices when extrapolated to the mantle), suggesting that the composition found by the probe may be representative of the entire planet. Interior models derived from this first-principles EOS do not give a match to Jupiter's gravity moment J4 unless one invokes interior differential rotation, implying that jovian interior dynamics has an observable effect on the measured gravity field. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.4264v1.pdf"}
{"id": "0808.0242", "abstract": "  The connection between the geometric phase and quantum phase transition has been discussed extensively in the two-band model. By introducing the twist operator, the geometric phase can be defined by calculating its ground-state expectation value. In contrast to the previous numerical examinations, our discussion presents an exact calculation for the determination of the geometric phase. Through two representative examples, our calculation shows the intimate connection between the geometric phase and phase transition: different behaviors of the geometric phase can be identified in this paper, which are directly related to the energy gap above the ground state. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.0242v1.pdf"}
{"id": "0808.1521", "abstract": "  This is the first of a series of papers devoted to the investigation of a large sample of brightest cluster galaxies (BCGs), their kinematic and stellar population properties, and the relationships between those and the properties of the cluster. We have obtained high signal-to-noise ratio, long-slit spectra of these galaxies with Gemini and WHT with the primary purpose of investigating their stellar population properties. This paper describes the selection methods and criteria used to compile a new sample of galaxies, concentrating on BCGs previously classified as containing a halo (cD galaxies), together with the observations and data reduction. Here, we present the full sample of galaxies, and the measurement and interpretation of the radial velocity and velocity dispersion profiles of 41 BCGs. We find clear rotation curves for a number of these giant galaxies. In particular, we find rapid rotation (> 100 km/s) for two BCGs, NGC6034 and NGC7768, indicating that it is unlikely that they formed through dissipationless mergers. Velocity substructure in the form of kinematically decoupled cores is detected in 12 galaxies, and we find five galaxies with velocity dispersion increasing with radius. The amount of rotation, the velocity substructure and the position of BCGs on the anisotropy-luminosity diagram are very similar to those of \"ordinary\" giant ellipticals in high density environments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.1521v1.pdf"}
{"id": "0808.1941", "abstract": "  We examine the coupling of electromagnetic waves incident normal to a thin silver film that forms an oscillatory grating embedded between two otherwise uniform, semi-infinite half spaces. Two grating structures are considered, in one of which the mid point of the Ag film remains fixed whereas the thickness varies sinusoidally, while in the other the mid point oscillates sinusoidally whereas the film thicknesses remains fixed. On reducing the light wavelength from the long wavelength limit, we encounter signatures in the transmission, T, and reflection, R, coefficients associated with: i) the short-range surface plasmon mode, ii) the long-range surface plasmon mode, and iii) electromagnetic diffraction tangent to the grating. The first two features can be regarded as generalized (plasmon) Wood's anomalies whereas the third is the first-order conventional (electromagnetic) Wood's anomaly. The energy density at the film surface is enhanced for wavelengths corresponding to these three anomalies, particularly for the long range plasmon mode in thin films. When exciting the silver film with a pair of waves incident from opposite directions, we find that by adjusting the grating oscillation amplitude and fixing the relative phase of the incoming waves to be even or odd, T+R can be made to vanish for one or the other of the plasmon modes; this corresponds to perfect coupling (impedance matching in the language of electrical engineering) between the incoming light and these modes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.1941v2.pdf"}
{"id": "0808.3878", "abstract": "  Warps in the outer gaseous disks of galaxies are a ubiquitous phenomenon, but it is unclear what generates them. One theory is that warps are generated internally through spontaneous bending instabilities. Other theories suggest that they result from the interaction of the outer disk with accreting extragalactic material. In this case, we expect to find cases where the circular velocity of the warp gas is poorly correlated with the rotational velocity of the galaxy disk at the same radius. Optical spectroscopy presents itself as an interesting alternative to 21-cm observations for testing this prediction, because (i) separating the kinematics of the warp from those of the disk requires a spatial resolution that is higher than what is achieved at 21 cm at low HI column density; (ii) optical spectroscopy also provides important information on star formation rates, gas excitation, and chemical abundances, which provide clues to the origin of the gas in warps. We present here preliminary results of a study of the kinematics of gas in the outer-disk warps of seven edge-on galaxies, using multi-hour VLT/FORS2 spectroscopy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.3878v1.pdf"}
{"id": "0809.0136", "abstract": "  We study the Brownian motion of particles trapped by optical tweezers inside a colloidal glass (Laponite) during the sol-gel transition. We use two methods based on passive rheology to extract the effective temperature from the fluctuations of the Brownian particles. All of them give a temperature that, within experimental errors, is equal to the heat bath temperature. Several interesting features concerning the statistical properties and the long time correlations of the particles are observed during the transition. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.0136v1.pdf"}
{"id": "0809.0481", "abstract": "  We introduce solvable stochastic dealer models, which can reproduce basic empirical laws of financial markets such as the power law of price change. Starting from the simplest model that is almost equivalent to a Poisson random noise generator, the model becomes fairly realistic by adding only two effects, the self-modulation of transaction intervals and a forecasting tendency, which uses a moving average of the latest market price changes. Based on the present microscopic model of markets, we find a quantitative relation with market potential forces, which has recently been discovered in the study of market price modeling based on random walks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.0481v2.pdf"}
{"id": "0809.3802", "abstract": "  Yan and Lazarian have proposed a new technique through which the magnetic field geometry in the diffuse interstellar medium, or in circumstellar matter, could be determined from the linear polarization of interstellar absorption or fluorescence emission lines from ions pumped by an anisotropic illuminating flux. New long-slit spectroscopic observations of the reflection nebula NGC2023, obtained with the Southern African Large Telescope Robert Stobie Spectrograph (RSS), have detected a number of atomic fluorescence lines of OI, NI, SiII, and FeII for the first time in a neutral medium. A model which predicts these lines and others illustrates which lines would be appropriate targets for an RSS spectropolarimetric investigation of this new diagnostic. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.3802v1.pdf"}
{"id": "0810.1194", "abstract": "  The photoproduction of K+ mesons is an important challenge to recent QCD based chiral perturbation theories in the strange quark sector and is an important constraint on the nucleon excitation spectrum. We present preliminary data from a new high precision measurement using the Crystal Ball detector. The measurement pioneers a new technique for tagging strangeness using detailed cluster analysis in segmented calorimeters which has potential wider application at present and future hadron physics facilities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.1194v1.pdf"}
{"id": "0810.2804", "abstract": "  The hadronization of an expanding partonic fireball is studied within the Parton-Hadron-Strings Dynamics (PHSD) approach which is based on a dynamical quasiparticle model (DQPM) matched to reproduce lattice QCD results in thermodynamic equilibrium. Apart from strong parton interactions the expansion and development of collective flow is found to be driven by strong gradients in the parton mean-fields. An analysis of the elliptic flow v_2 demonstrates a linear correlation with the spatial eccentricity ϵ as in case of ideal hydrodynamics. The hadronization occurs by quark-antiquark fusion or 3 quark/3 antiquark recombination which is described by covariant transition rates. Since the dynamical quarks become very massive, the formed resonant 'pre-hadronic' color-dipole states (qq̅ or qqq) are of high invariant mass, too, and sequentially decay to the groundstate meson and baryon octets increasing the total entropy. This solves the entropy problem in hadronization in a natural way. Hadronic particle ratios turn out to be in line with those from a grandcanonical partition function at temperature T ≈ 170 MeV. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.2804v1.pdf"}
{"id": "0810.3570", "abstract": "  Recent results from HERA and TevaTron on precision tests of QCD with jets, W and Z bosons and photons associated with jets and heavy flavours are presented. The measurements were used to probe QCD at the highest energies, to provide experimental constraints on SM processes that constitute background to new physics, to extract values of the coupling of the strong interaction and to constrain the proton parton distribution functions. The implications of the results on LHC physics are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.3570v1.pdf"}
{"id": "0810.3826", "abstract": "  Delayed choice and quantum eraser experiments have attracted much interest recently, both theoretically and experimentally. In particular, they have prompted suggestions that quantum mechanics involves acausal effects. Using a recently developed approach which takes apparatus into account, we present a detailed analysis of various double-slit experiments to show that this is never the case. Instead, quantum experiments can be described in terms of a novel concept of time called stages. These can cut across the conventional linear time parameter as experienced in the laboratory and appear to violate causality. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.3826v1.pdf"}
{"id": "0810.4102", "abstract": "  We combine spectroscopic metallicity values with integrated narrowband continuum colors to explore the internal metallicity distribution in early-type galaxies. The different techniques for determining metallicity (indices versus colors) allows for an estimate of the contribution from metal-poor stars in a predominantly metal-rich population which, in turn, places constraints on the shape and width of a galaxy's metallicity distribution function (MDF). The color-spectroscopic data is compared to the closed box, infall and inhomogeneous chemical evolution models. The G-dwarf problem, a deficiency in metal-poor stars as compared to closed box models, is evident in the dataset and indicates this deficiency is common to all early-type galaxies. However, even simple infall models predict galaxy colors which are too blue compared to the observations. A simple analytic model is proposed which matches the elliptical data and recent HST observations of M31 (Worthey et al 2005) and NGC 5128 (Harris     Harris 2000) by reducing the number of metal-poor stars in a systematic fashion. While without physical justification, the shape of these models are similar to predictions of inhomogeneous enrichment scenarios. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.4102v1.pdf"}
{"id": "0811.1420", "abstract": "  The glass transition in binary mixtures of star polymers is studied by mode coupling theory and extensive molecular dynamics computer simulations. In particular, we have explored vitrification in the parameter space of size asymmetry δ and concentration ρ_2 of the small star polymers at fixed concentration of the large ones. Depending on the choice of parameters, three different glassy states are identified: a single glass of big polymers at low δ and low ρ_2, a double glass at high δ and low ρ_2, and a novel double glass at high ρ_2 and high δ which is characterized by a strong localization of the small particles. At low δ and high ρ_2 there is a competition between vitrification and phase separation. Centered in the (δ, ρ_2)-plane, a liquid lake shows up revealing reentrant glass formation. We compare the behavior of the dynamical density correlators with the predictions of the theory and find remarkable agreement between the two. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.1420v1.pdf"}
{"id": "0811.2056", "abstract": "  We study the performance of a quantum wire spin filter that is based on the Rashba spin-orbit interaction in the presence of the electron-electron interaction. The finite length wire is attached to two semi-infinite nonmagnetic leads. Analyzing the spin polarization of the linear conductance at zero temperature, we show that spin-filtering is possible by adequate tuning of the system parameters first considering noninteracting electrons. Next, the functional renormalization group method is used to capture correlation effects induced by the Coulomb interaction. For short wires we show that the energy regime in which spin polarization is found is strongly affected by the Coulomb interaction. For long wires we find the power-law suppression of the total conductance on low energy scales typical for inhomogeneous Luttinger liquids while the degree of spin polarization stays constant. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.2056v1.pdf"}
{"id": "0811.2329", "abstract": "  Detecting communities in complex networks accurately is a prime challenge, preceding further analyses of network characteristics and dynamics. Until now, community detection took into account only positively valued links, while many actual networks also feature negative links. We extend an existing Potts model to incorporate negative links as well, resulting in a method similar to the clustering of signed graphs, as dealt with in social balance theory, but more general. To illustrate our method, we applied it to a network of international alliances and disputes. Using data from 1993–2001, it turns out that the world can be divided into six power blocs similar to Huntington's civilizations, with some notable exceptions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.2329v3.pdf"}
{"id": "0811.2749", "abstract": "  We have investigated the effects of uniform rotation and a specific model for differential rotation on the pulsation frequencies of 10  stellar models. Uniform rotation decreases the frequencies for all modes. Differential rotation does not appear to have a significant effect on the frequencies, except for the most extreme differentially rotating models. In all cases, the large and small separations show the effects of rotation at lower velocities than do the individual frequencies. Unfortunately, to a certain extent, differential rotation mimics the effects o f more rapid rotation, and only the presence of some specific observed frequencies with well identified modes will be able to uniquely constrain the internal rotation of pulsating stars. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.2749v1.pdf"}
{"id": "0811.3154", "abstract": "  We study the transient statistical properties of short and long Josephson junctions under the influence of thermal and correlated fluctuations. In particular, we investigate the lifetime of the superconductive metastable state finding the presence of noise induced phenomena. For short Josephson junctions we investigate the lifetime as a function both of the frequency of the current driving signal and the noise intensity and we find how these noise-induced effects are modified by the presence of a correlated noise source. For long Josephson junctions we integrate numerically the sine-Gordon equation calculating the lifetime as a function of the length of the junction both for inhomogeneous and homogeneous bias current distributions. We obtain a nonmonotonic behavior of the lifetime as a function of the frequency of the current driving signal and the correlation time of the noise. Moreover we find two maxima in the nonmonotonic behaviour of the mean escape time as a function of the correlated noise intensity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.3154v1.pdf"}
{"id": "0811.4034", "abstract": "  We describe the method allowing quantitative interpretation of absorptive images of mixtures of BEC and thermal atoms which reduces possible systematic errors associated with evaluation of the contribution of each fraction. By using known temperature dependence of the BEC fraction, the analysis allows precise calibration of the fitting results. The developed method is verified in two different measurements and compares well with theoretical calculations and with measurements performed by another group. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.4034v1.pdf"}
{"id": "0812.0055", "abstract": "  Recent developments in lipid membrane models for simulations are reviewed. To reduce computational costs, various coarse-grained molecular models have been proposed. Among them, implicit solvent (solvent-free) molecular models are relatively more coarse-grained and efficient for simulating large bilayer membranes. On a μm scale, the molecular details are typically negligible and the membrane can be described as a continuous curved surface. The theoretical models for fluid and elastic membranes with mesh or meshless discretizations are presented. As examples of applications, the dynamics of vesicles in flows, vesicle formation, and membrane fusion are presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.0055v1.pdf"}
{"id": "0812.0083", "abstract": "  The Radiotherapy treatment planning optimization process based on a quasi-Newton algorithm with an object function containing dose-volume constraints is not guaranteed to converge when the dose value in the dose-volume constraint is a critical value of the dose distribution. This is caused by finite differentiability of the dose-volume histogram at such values. A closer look near such values reveals that convergence is most likely not at stake, but it might be slowed down. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.0083v1.pdf"}
{"id": "0812.1763", "abstract": "  These days it is common for young operator algebraists to know a lot about C*-algebras, or a lot about von Neumann algebras – but not both. Though a natural consequence of the breadth and depth of each subject, this is unfortunate as the interplay between the two theories has deep historical roots and has led to many beautiful results. We review some of these connections, in the context of amenability, with the hope of convincing (younger) readers that tribalism impedes progress. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.1763v1.pdf"}
{"id": "0812.3112", "abstract": "  Motivated by many recent experimental studies of non-classical rotational inertia (NCRI) in superfluid and supersolid samples, we present a study of the hydrodynamics of a superfluid confined in the two-dimensional region (equivalent to a long cylinder) between two concentric arcs of radii b and a (b<a) subtending an angle β, with 0 ≤β≤ 2π. The case β= 2 π corresponds to a blocked ring. We discuss the methodology to compute the NCRI effects, and calculate these effects both for small angular velocities, when no vortices are present, and in the presence of a vortex. We find that, for a blocked ring, the NCRI effect is small, and that therefore there will be a large discontinuity in the moment of inertia associated with blocking or unblocking circular paths. For blocked wedges (b=0) with β > π, we find an unexpected divergence of the velocity at the origin, which implies the presence of either a region of normal fluid or a vortex for any nonzero value of the angular velocity. Implications of our results for experiments on \"supersolid\" behavior in solid ^4 He are discussed. A number of mathematical issues are pointed out and resolved. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.3112v1.pdf"}
{"id": "0812.4605", "abstract": "  Cyclical wind variability is an ubiquitous but as yet unexplained feature among OB stars. The O7.5 III(n)((f)) star xi Persei is the brightest representative of this class on the Northern hemisphere. As its prominent cyclical wind properties vary on a rotational time scale (2 or 4 days) the star has been already for a long time a serious magnetic candidate. As the cause of this enigmatic behavior non-radial pulsations and/or a surface magnetic field are suggested. We present a preliminary report on our attempts to detect a magnetic field in this star with high-resolution measurements obtained with the spectropolarimeter Narval at TBL, France during 2 observing runs of 5 nights in 2006 and 5 nights in 2007. Only upper limits could be obtained, even with the longest possible exposure times. If the star hosts a magnetic field, its surface strength should be less than about 300 G. This would still be enough to disturb the stellar wind significantly. From our new data it seems that the amplitude of the known non-radial pulsations has changed within less than a year, which needs further investigation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.4605v1.pdf"}
{"id": "0901.1167", "abstract": "  A self-focusing of a coasting relativistic beam in a plasma channel that is confined by an external magnetic field is studied as a means of reconditioning the beam emerging from a beam injector [a radio frequency quadrupole (RFQ)] for a linac. A detailed study of the beam stability in the self-focused beam has been carried out. In order to explain beam filaments and the resistive hose instability in a unified way, we treat all the azimuthal modes in the derivation of the dispersion relation in a finite plasma channel that exhibit many unstable modes, which are classified by Weinberg's scheme [Steven Weinberg, J. Math. 8, 614 (1967)]. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.1167v2.pdf"}
{"id": "0901.2702", "abstract": "  In this paper we describe in detail the implementation and main properties of a new inversion code for the polarized radiative transfer equation (VFISV: Very Fast inversion of the Stokes vector). VFISV will routinely analyze pipeline data from the Helioseismic and Magnetic Imager (HMI) on-board of the Solar Dynamics Observatory (SDO). It will provide full-disk maps (4096×4096 pixels) of the magnetic field vector on the Solar Photosphere every 10 minutes. For this reason VFISV is optimized to achieve an inversion speed that will allow it to invert 16 million pixels every 10 minutes with a modest number (approx. 50) of CPUs. Here we focus on describing a number of important details, simplifications and tweaks that have allowed us to significantly speed up the inversion process. We also give details on tests performed with data from the spectropolarimeter on-board of the Hinode spacecraft. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.2702v1.pdf"}
{"id": "0902.0007", "abstract": "  We present the theory of a Josephson parametric amplifier employing two pump sources. Our calculations are based on Input-Output Theory, and can easily be generalized to any coupled system involving parametric interactions. We analyze the operation of the device, taking into account the feedback introduced by the reaction of the signal and noise on the pump power, and in this framework, compute the response functions of interest - signal and idler gains, internal gain of the amplifier, and self-oscillation signal amplitude. To account for this back-action between signal and pump, we adopt a mean-field approach and self-consistently explore the boundary between amplification and self-oscillation. The coincidence of bifurcation and self-oscillation thresholds reveals that the origin of coherent emission of the amplifier lies in the multi-wave mixing of the noise components. Incorporation of the back-action leads the system to exhibit hysteresis, dependent on parameters like temperature and detuning from resonance. Our analysis also shows that the resonance condition itself changes in the presence of back-action and this can be understood in terms of the change in plasma frequency of the junction. The potential of the double pump amplifier for quantum-limited measurements and as a squeezer is also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.0007v2.pdf"}
{"id": "0902.1287", "abstract": "  Gravitational wave emission from extreme mass ratio binaries (EMRBs) should be detectable by the joint NASA-ESA LISA project, spurring interest in analytical and numerical methods for investigating EMRBs. We describe a discontinuous Galerkin (dG) method for solving the distributionally forced 1+1 wave equations which arise when modeling EMRBs via the perturbation theory of Schwarzschild blackholes. Despite the presence of jump discontinuities in the relevant polar and axial gravitational \"master functions\", our dG method achieves global spectral accuracy, provided that we know the instantaneous position, velocity, and acceleration of the small particle. Here these variables are known, since we assume that the particle follows a timelike geodesic of the Schwarzschild geometry. We document the results of several numerical experiments testing our method, and in our concluding section discuss the possible inclusion of gravitational self-force effects. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.1287v2.pdf"}
{"id": "0902.2352", "abstract": "  In this paper we introduce a three-dimensional version of the Mercedes-Benz model to describe water molecules. In this model van der Waals interactions and hydrogen bonds are given explicitly through a Lennard-Jones potential and a Gaussian orientation-dependent terms, respectively. At low temperature the model freezes forming Ice-I and it reproduces the main peaks of the experimental radial distribution function of water. In addition to these structural properties, the model also captures the thermodynamical anomalies of water: the anomalous density profile, the negative thermal expansivity, the large heat capacity and the minimum in the isothermal compressibility. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.2352v1.pdf"}
{"id": "0902.2663", "abstract": "  We propose a novel protocol for storage and retrieval of photon wave packets in a Λ-type atomic medium. This protocol derives from spectral hole burning and takes advantages of the specific properties of solid state systems at low temperature, such as rare earth ion doped crystals. The signal pulse is tuned to the center of the hole that has been burnt previously within the inhomogeneously broadened absorption band. The group velocity is strongly reduced, being proportional to the hole width. This way the optically carried information and energy is carried over to the off-resonance optical dipoles. Storage and retrieval are performed by conversion to and from ground state Raman coherence by using brief π-pulses. The protocol exhibits some resemblance with the well known electromagnetically induced transparency process. It also presents distinctive features such as the absence of coupling beam. In this paper we detail the various steps of the protocol, summarize the critical parameters and theoretically examine the recovery efficiency. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.2663v1.pdf"}
{"id": "0902.2845", "abstract": "  The present paper is related to a talk presented during the Symposium on Coherent Control and Ultracold Chemistry held during the Sixth Congress of the International Society for Theoretical Chemical Physics (ISTCP-VI, July 2008). The talk was entitled \"Electronic structure properties of alkali dimers and trimers. Prospects for alignment of ultracold molecules\". Here we report on the electrostatic repulsion forces of the ionic cores at short separation, involved when the potential energy surfaces of alkali trimers are calculated with a quantum chemistry approach based on effective large-core potentials for ionic core description. We demonstrate that such forces in the triatomic molecule can be obtained as the sum of three pairwise terms. We illustrate our results on the lowest electronic states of Cs_3, which are computed for the first time within a full configuration interaction based on a large Gaussian basis set. As a preliminary section, we also propose a brief introduction about the importance of alkali trimer systems in the context of cold and ultracold molecules. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.2845v1.pdf"}
{"id": "0902.3221", "abstract": "  In order to fully exploit the physics potential of the ILC, it will be necessary to measure (and control) beam parameters to a permille level precision. In case of the beam polarisation, this can only be achieved with dedicated high energy Compton polarimeters and by improving the detector linearity, as well as the calibration of the analyzing power.   This note summarises results of an early testbeam period with the Cherenkov detector of the SLD polarimeter, linearity measurements of readout electronics and photodetectors and compares simulation results of the SLD Cherenkov detector with those of a new `U-shaped' prototype. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.3221v1.pdf"}
{"id": "0903.4231", "abstract": "  The success of Berry phases in quantum mechanics stimulated the study of similar phenomena in other areas of physics, including the theory of living cell locomotion and motion of patterns in nonlinear media. More recently, geometric phases have been applied to systems operating in a strongly stochastic environment, such as molecular motors. We discuss such geometric effects in purely classical dissipative stochastic systems and their role in the theory of the stochastic pump effect (SPE). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.4231v2.pdf"}
{"id": "0903.4858", "abstract": "  We develop an effective low energy theory for multi-channel scattering of cold atomic alkali atoms with particular focus on Feshbach resonances. The scattering matrix is expressed in terms of observables only and the theory allows for the inclusion of many-body effects both in the open and in the closed channels.   We then consider the frequency and damping of collective modes for Fermi gases and demonstrate how medium effects significantly increase the scattering rate determining the nature of the modes. Our results obtained with no fitting parameters are shown to compare well with experimental data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.4858v2.pdf"}
{"id": "0904.0667", "abstract": "  We propose a scenario of quantum memory for light based on Raman scattering. The storage medium is a vapor and the different spectral components of the incoming signal are stored in different atomic velocity classes. One uses appropriate pulses to reverse the resulting Doppler phase shift and to regenerate the signal, without distortion, in the backward direction. The different stages of the protocol are detailed and the recovery efficiency is calculated in the semi-classical picture. Since the memory bandwidth is determined by the Raman transition Doppler width, it can be adjusted by changing the angle of the signal and control beams. The optical depth also depends on the beam angle. As a consequence the available optical depth can be optimized, depending on the needed bandwidth. The predicted recovery efficiency is close to 100", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0904/0904.0667v1.pdf"}
{"id": "0904.1723", "abstract": "  We investigate theoretically the evolution of the two-point density correlation function of a low-dimensional ultracold Bose gas after release from a tight transverse confinement. In the course of expansion thermal and quantum fluctuations present in the trapped systems transform into density fluctuations. For the case of free ballistic expansion relevant to current experiments, we present simple analytical relations between the spectrum of “density ripples” and the correlation functions of the original confined systems. We analyze several physical regimes, including weakly and strongly interacting one-dimensional (1D) Bose gases and two-dimensional (2D) Bose gases below the Berezinskii-Kosterlitz-Thouless (BKT) transition. For weakly interacting 1D Bose gases, we obtain an explicit analytical expression for the spectrum of density ripples which can be used for thermometry. For 2D Bose gases below the BKT transition, we show that for sufficiently long expansion times the spectrum of the density ripples has a self-similar shape controlled only by the exponent of the first-order correlation function. This exponent can be extracted by analyzing the evolution of the spectrum of density ripples as a function of the expansion time. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0904/0904.1723v3.pdf"}
{"id": "0904.3696", "abstract": "  We study fluctuations of the number of photocounts measured by an ideal photodetector illuminated by light scattered in an amplifying disordered medium, below the threshold for random lasing. We show that the variance of fluctuations and their correlation function carry information about fluctuating properties of the medium. A direct link is established between the fluctuations of the number of photocounts due to the amplified spontaneous emission (ASE) and the dimensionless conductance g of the medium. Our results suggest a possibility of probing amplifying disordered media by analyzing statistics of their ASE, without illuminating them from outside by a probe beam. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0904/0904.3696v1.pdf"}
{"id": "0905.2002", "abstract": "  A systematic comparison is conducted for pairing properties of finite systems at nonzero temperature as predicted by the exact solutions of the pairing problem embedded in three principal statistical ensembles, as well as the unprojected (FTBCS1+SCQRPA) and Lipkin-Nogami projected (FTLN1+SCQRPA) theories that include the quasiparticle number fluctuation and coupling to pair vibrations within the self-consistent quasiparticle random-phase approximation. The numerical calculations are performed for the pairing gap, total energy, heat capacity, entropy, and microcanonical temperature within the doubly-folded equidistant multilevel pairing model. The FTLN1+SCQRPA predictions agree best with the exact grand-canonical results. In general, all approaches clearly show that the superfluid-normal phase transition is smoothed out in finite systems. A novel formula is suggested for extracting the empirical pairing gap in reasonable agreement with the exact canonical results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.2002v1.pdf"}
{"id": "0905.4948", "abstract": "  It is argued that ultracold quantum degenerate gas of ytterbium ^173Yb atoms having nuclear spin I = 5/2 exhibits an enlarged SU(6) symmetry. Within the Landau Fermi liquid theory, stability criteria against Fermi liquid (Pomeranchuk) instabilities in the spin channel are considered. Focusing on the SU(n > 2) generalizations of ferromagnetism, it is shown within mean-field theory that the transition from the paramagnet to the itinerant ferromagnet is generically first order. On symmetry grounds, general SU(n) itinerant ferromagnetic ground states and their topological excitations are also discussed. These SU(n > 2) ferromagnets can become stable by increasing the scattering length using optical methods or in an optical lattice. However, in an optical lattice at current experimental temperatures, Mott states with different filling are expected to coexist in the same trap, as obtained from a calculation based on the SU(6) Hubbard model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.4948v3.pdf"}
{"id": "0906.2098", "abstract": "  We discuss a class of chain graph models for categorical variables defined by what we call a multivariate regression chain graph Markov property. First, the set of local independencies of these models is shown to be Markov equivalent to those of a chain graph model recently defined in the literature. Next we provide a parametrization based on a sequence of generalized linear models with a multivariate logistic link function that captures all independence constraints in any chain graph model of this kind. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.2098v3.pdf"}
{"id": "0906.3865", "abstract": "  We perform investigation of Hubbard model with interaction between strongly correlated conducting electrons on a lattice with Debye phonons. To solve the problem generalized dynamical mean-field DMFT+Σmethod is employed with \"external\" self-energy Σ_ph corresponding to electron-phonon interaction. We present DMFT+Σ_ph results for densities of states and kinks in energy dispersions for a variety of model parameters, analyzing the interplay of recently discovered kinks of purely electronic nature and usual phonon kinks in the electronic spectrum. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.3865v1.pdf"}
{"id": "0906.4527", "abstract": "  I review two mechanisms by which gravitational waves can be generated at the end of inflation: preheating, and gravitons Hawking radiated during the decay of very small primordial black holes. These mechanisms are contrasted with the gravitational waves during inflation, and may provide a window into the physical processes that govern the end of the inflationary phase. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.4527v1.pdf"}
{"id": "0907.1009", "abstract": "  Supernova Remnants (SNRs) are believed to be the acceleration sites of galactic cosmic rays. As such they are expected to produce Very High Energy (VHE) gamma-rays through hadronic and/or electromagnetic scenarios, hence they are natural targets for observations with ground-based Imaging Atmospheric Cherenkov Telescopes (IACTs). Currently, VHE emission has been detected from several SNRs, making them one of the most abundant types of established galactic VHE sources. The MAGIC telescope, located in the Canary island of La Palma, has been performing observations of several SNRs over the last two years. Parameters like age, distance, radio flux, or possible EGRET association (i.e., criteria matching those already used for previous successful IACT SNR detections), were used to select candidate targets. Here we summarize the results of the past two years of observations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.1009v2.pdf"}
{"id": "0907.3430", "abstract": "  We present a dynamical field theory for directed randomly branched polymers and in particular their collapse transition. We develop a phenomenological model in the form of a stochastic response functional that allows us to address several interesting problems such as the scaling behavior of the swollen phase and the collapse transition. For the swollen phase, we find that by choosing model parameters appropriately, our stochastic functional reduces to the one describing the relaxation dynamics near the Yang-Lee singularity edge. This corroborates that the scaling behavior of swollen branched polymers is governed by the Yang-Lee universality class as has been known for a long time. The main focus of our paper lies on the collapse transition of directed branched polymers. We show to arbitrary order in renormalized perturbation theory with ε-expansion that this transition belongs to the same universality class as directed percolation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.3430v2.pdf"}
{"id": "0907.5438", "abstract": "  Many basic key distribution schemes specifically tuned to wireless sensor networks have been proposed in the literature. Recently, several researchers have proposed schemes in which they have used group-based deployment models and assumed predeployment knowledge of the expected locations of nodes. They have shown that these schemes achieve better performance than the basic schemes, in terms of connectivity, resilience against node capture and storage requirements. But in many situations expected locations of nodes are not available. In this paper we propose a solution which uses the basic scheme, but does not use group-based deployment model and predeployment knowledge of the locations of nodes, and yet performs better than schemes which make the aforementioned assumptions.   In our scheme, groups are formed after deployment of sensor nodes, on the basis of their physical locations, and the nodes sample keys from disjoint key pools. Compromise of a node affects secure links with other nodes that are part of its group only. Because of this reason, our scheme performs better than the basic schemes and the schemes using predeployment knowledge, in terms of connectivity, storage requirement, and security. Moreover, the post-deployment key generation process completes sooner than in schemes like LEAP+. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.5438v2.pdf"}
{"id": "0908.0019", "abstract": "  We generalize the discrete quantum walk on the line using a time dependent unitary coin operator. We find an analytical relation between the long-time behaviors of the standard deviation and the coin operator. Selecting the coin time sequence allows to obtain a variety of predetermined asymptotic wave-function spreadings: ballistic, sub-ballistic, diffusive, sub-diffusive and localized. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0908/0908.0019v2.pdf"}
{"id": "0908.1163", "abstract": "  In this paper, code pairs based on trellis coded modulation are proposed over PSK signal sets for a two-user Gaussian multiple access channel. In order to provide unique decodability property to the receiver and to maximally enlarge the constellation constrained (CC) capacity region, a relative angle of rotation is introduced between the signal sets. Subsequently, the structure of the sum alphabet of two PSK signal sets is exploited to prove that Ungerboeck labelling on the trellis of each user maximizes the guaranteed minimum squared Euclidean distance, d^2_g, min in the sum trellis. Hence, such a labelling scheme can be used systematically to construct trellis code pairs for a two-user GMAC to approach any rate pair within the capacity region. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0908/0908.1163v1.pdf"}
{"id": "0908.1377", "abstract": "  We investigate the star formation history of the universe using FIREWORKS, a multiwavelength survey of the CDFS. We study the evolution of the specific star formation rate (sSFR) with redshift in different mass bins from z = 0 to z   3. We find that the sSFR increases with redshift for all masses. The logarithmic increase of the sSFR with redshift is nearly independent of mass, but this cannot yet be verified at the lowest-mass bins at z > 0.8, due to incompleteness. We convert the sSFRs to a dimensionless growth rate to facilitate a comparison with a semi-analytic galaxy formation model that was implemented on the Millennium Simulation. The model predicts that the growth rates and sSFRs increase similarly with redshift for all masses, consistent with the observations. However, we find that for all masses, the inferred observed growth rates increase more rapidly with redshift than the model predictions. We discuss several possible causes for this discrepancy, ranging from field-to-field variance, conversions to SFR, and shape of the IMF. We find that none of these can solve the discrepancy completely. We conclude that the models need to be adapted to produce the steep increase in growth rate between redshift z=0 and z=1. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0908/0908.1377v1.pdf"}
{"id": "0908.1948", "abstract": "  Interference is a major issue that limits the performance in wireless networks, and cooperation among receivers can help mitigate interference by forming distributed MIMO systems. The rate at which receivers cooperate, however, is limited in most scenarios. How much interference can one bit of receiver cooperation mitigate? In this paper, we study the two-user Gaussian interference channel with conferencing decoders to answer this question in a simple setting. We characterize the fundamental gain from cooperation: at high SNR, when INR is below 50", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0908/0908.1948v2.pdf"}
{"id": "0909.0045", "abstract": "  Quantum interference is investigated within the complex quantum Hamilton-Jacobi formalism. As shown in a previous work [Phys. Rev. Lett. 102, 250401 (2009)], complex quantum trajectories display helical wrapping around stagnation tubes and hyperbolic deflection near vortical tubes, these structures being prominent features of quantum caves in space-time Argand plots. Here, we further analyze the divergence and vorticity of the quantum momentum function along streamlines near poles, showing the intricacy of the complex dynamics. Nevertheless, despite this behavior, we show that the appearance of the well-known interference features (on the real axis) can be easily understood in terms of the rotation of the nodal line in the complex plane. This offers a unified description of interference as well as an elegant and practical method to compute the lifetime for interference features, defined in terms of the average wrapping time, i.e., considering such features as a resonant process. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.0045v2.pdf"}
{"id": "0909.1314", "abstract": "  We consider finite-range effects when the scattering length goes to zero near a magnetically controlled Feshbach resonance. The traditional effective-range expansion is badly behaved at this point and we therefore introduce an effective potential that reproduces the full T-matrix. To lowest order the effective potential goes as momentum squared times a factor that is well-defined as the scattering length goes to zero. The potential turns out to be proportional to the background scattering length squared times the background effective range for the resonance. We proceed to estimate the applicability and relative importance of this potential for Bose-Einstein condensates and for two-component Fermi gases where the attractive nature of the effective potential can lead to collapse above a critical particle number or induce instability toward pairing and superfluidity. For broad Feshbach resonances the higher-order effect is completely negligible. However, for narrow resonances in tightly confined samples signatures might be experimentally accessible. This could be relevant for sub-optical wavelength microstructured traps at the interface of cold atoms and solid-state surfaces. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.1314v6.pdf"}
{"id": "0909.1596", "abstract": "  We study open quantum systems whose evolution is governed by a master equation of Kossakowski-Gorini-Sudarshan-Lindblad type and give a characterization of the convex set of steady states of such systems based on the generalized Bloch representation. It is shown that an isolated steady state of the Bloch equation cannot be a center, i.e., that the existence of a unique steady state implies attractivity and global asymptotic stability. Necessary and sufficient conditions for the existence of a unique steady state are derived and applied to different physical models including two- and four-level atoms, (truncated) harmonic oscillators, composite and decomposable systems. It is shown how these criteria could be exploited in principle for quantum reservoir engineeing via coherent control and direct feedback to stabilize the system to a desired steady state. We also discuss the question of limit points of the dynamics. Despite the non-existence of isolated centers, open quantum systems can have nontrivial invariant sets. These invariant sets are center manifolds that arise when the Bloch superoperator has purely imaginary eigenvalues and are closely related to decoherence-free subspaces. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.1596v3.pdf"}
{"id": "0909.3439", "abstract": "  We analyze the suppression of decoherence by means of dynamical decoupling in the pure-dephasing spin-boson model for baths with power law spectra. The sequence of ideal π pulses is optimized according to the power of the bath. We expand the decoherence function and separate the cancelling divergences from the relevant terms. The proposed sequence is chosen to be the one minimizing the decoherence function. By construction, it provides the best performance. We analytically derive the conditions that must be satisfied. The resulting equations are solved numerically. The solutions are very close to the Carr-Purcell-Meiboom-Gill (CPMG) sequence for a soft cutoff of the bath while they approach the Uhrig dynamical-decoupling (UDD) sequence as the cutoff becomes harder. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.3439v1.pdf"}
{"id": "0909.3688", "abstract": "  Web-fraud is one of the most unpleasant features of today's Internet. Two well-known examples of fraudulent activities on the web are phishing and typosquatting. Their effects range from relatively benign (such as unwanted ads) to downright sinister (especially, when typosquatting is combined with phishing). This paper presents a novel technique to detect web-fraud domains that utilize HTTPS. To this end, we conduct the first comprehensive study of SSL certificates. We analyze certificates of legitimate and popular domains and those used by fraudulent ones. Drawing from extensive measurements, we build a classifier that detects such malicious domains with high accuracy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.3688v4.pdf"}
{"id": "0910.0551", "abstract": "  The behaviour of a quantum rod, pivoted at its lower end on an impenetrable floor and restricted to moving in the vertical plane under the gravitational potential is studied analytically under the approximation that the rod is initially localised to a small-enough neighbourhood around the point of classical unstable equilibrium. It is shown that the rod evolves out of this neighbourhood. The time required for this to happen, i.e., the tipping time is calculated using the semi-classical path integral. It is shown that equilibrium is recovered in the classical limit, and that our calculations are consistent with the uncertainty principle. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.0551v3.pdf"}
{"id": "0910.0991", "abstract": "  The Broad Emission Lines (BELs) in spectra of type 1 Active Galactic Nuclei (AGN) can be very complex, indicating a complex Broad Line Region (BLR) geometry. According to the standard unification model one can expect an accretion disk around a supermassive black hole in all AGN. Therefore, a disk geometry is expected in the BLR. However, a small fraction of BELs show double-peaked profiles which indicate the disk geometry. Here, we discuss a two-component model, assuming an emission from the accretion disk and one additional emission from surrounding region. We compared the modeled BELs with observed ones (mostly broad Hα and Hβ profiles) finding that the model can well describe single-peaked and double-peaked observed broad line profiles. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.0991v1.pdf"}
{"id": "0910.1325", "abstract": "  A monochromatic laser pumping a parametric down conversion crystal generates frequency entangled photon pairs. We study this experimentally by addressing such frequency entangled photons at telecommunication wavelengths (around 1550 nm) with fiber optics components such as electro-optic phase modulators and narrow band frequency filters. The theory underlying our approach is developed by introducing the notion of frequency bin entanglement. Our results show that the phase modulators address coherently up to eleven frequency bins, leading to an interference pattern which can violate a Bell inequality adapted to our setup by more than five standard deviations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.1325v2.pdf"}
{"id": "0910.2846", "abstract": "  The \"reaction\" of an extended body to the passage of an exact plane gravitational wave is discussed following Dixon's model. The analysis performed shows several general features, e.g. even if initially absent, the body acquires a spin induced by the quadrupole structure, the center of mass moves from its initial position, as well as certain \"spin-flip\" or \"spin-glitch\" effects which are being observed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.2846v1.pdf"}
{"id": "0910.2951", "abstract": "  The Vicsek model is a very popular individual based model which describes collective behavior among animal societies. A macroscopic version of the Vicsek model has been derived from a large scale limit of this individual based model <cit.>. In this work, we want to numerically validate this Macroscopic Vicsek model (MV). To this aim, we compare the simulations of the macroscopic and microscopic models one with each other. The MV model is a non-conservative hyperbolic equation with a geometric constraint. Due to the lack of theory for this kind of equations, we derive several equivalents for this system leading to specific numerical schemes. The numerical simulations reveal that the microscopic and macroscopic models are in good agreement provided that we choose one of the proposed formulations based on a relaxation of the geometric constraint. This confirms the relevance of the macroscopic equation but it also calls for a better theoretical understanding of this type of equations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.2951v1.pdf"}
{"id": "0910.3151", "abstract": "  Guided motion of emulsions is studied via combined experimental and theoretical investigations. The focus of the work is on basic issues related to driving forces generated via a step-wise (abrupt) change in wetting properties of the substrate along a given spatial direction. Experiments on binary emulsions unambiguously show that selective wettability of the one of the fluid components (water in our experiments) with respect to the two different parts of the substrate is sufficient in order to drive the separation process. These studies are accompanied by approximate analytic arguments as well as lattice Boltzmann computer simulations, focusing on effects of a wetting gradient on internal droplet dynamics as well as its relative strength compared to volumetric forces driving the fluid flow. These theoretical investigations show qualitatively different dependence of wetting gradient induced forces on contact angle and liquid volume in the case of an open substrate as opposed to a planar channel. In particular, for the parameter range of our experiments, slit geometry is found to give rise to considerably higher separation forces as compared to open substrate. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.3151v1.pdf"}
{"id": "0910.3591", "abstract": "  Dissensus is a modeling framework for networks of dynamic agents in competition for scarce resources. Originally inspired by biological cells behaviors, it fits also marketing, finance and many other application areas. Competition is often unstable in the sense that strong agents, those having access to large resources, gain more and more resources at the expense of weak agents. Thus, strong agents duplicate when reaching a critical amount of resources, whereas weak agents die when loosing all their resources. To capture all these phenomena we introduce systems with a discrete time gossip and unstable state dynamics interrupted by discrete events affecting the network topology. Invariancy of states and topologies and network connectivity are explored. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.3591v1.pdf"}
{"id": "0910.3603", "abstract": "  We develop necessary and sufficient conditions for uniqueness of the invariant measure of the filtering process associated to an ergodic hidden Markov model in a finite or countable state space. These results provide a complete solution to a problem posed by Blackwell (1957), and subsume earlier partial results due to Kaijser, Kochman and Reeds. The proofs of our main results are based on the stability theory of nonlinear filters. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.3603v2.pdf"}
{"id": "0910.5818", "abstract": "  The radioscience experiment is one of the on board experiment of the Mercury ESA mission BepiColombo that will be launched in 2014. The goals of the experiment are to determine the gravity field of Mercury and its rotation state, to determine the orbit of Mercury, to constrain the possible theories of gravitation (for example by determining the post-Newtonian (PN) parameters), to provide the spacecraft position for geodesy experiments and to contribute to planetary ephemerides improvement. This is possible thanks to a new technology which allows to reach great accuracies in the observables range and range rate; it is well known that a similar level of accuracy requires studying a suitable model taking into account numerous relativistic effects. In this paper we deal with the modelling of the space-time coordinate transformations needed for the light-time computations and the numerical methods adopted to avoid rounding-off errors in such computations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.5818v2.pdf"}
{"id": "0911.0131", "abstract": "  We propose here a robust scheme to infer the physical parameters of compact stars from their f-mode gravitational wave signals. We first show that the frequency and the damping rate of f-mode oscillation of compact stars can be expressed in terms of universal functions of stellar mass and moment of inertia. By employing the universality in the f-mode one can then infer accurate values of the mass, the moment of inertia and the radius of a compact star. In addition, we demonstrate that our new scheme works well for both realistic neutron stars and quark stars, and hence provides a unifying way to infer the physical parameters of compact stars. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0911/0911.0131v2.pdf"}
{"id": "0911.1607", "abstract": "  A summary of recent calculations of Casimir forces between a collection of N-dielectric spheres is presented. This is done by evaluating directly the force on a sphere constructed from a stress tensor, rather than an interaction energy. A loop integral formulation is also discussed where we rewrite the expressions for the force in terms of loop integrals for the effective classical propagation of the electric and magnetic fields. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0911/0911.1607v1.pdf"}
{"id": "0911.2570", "abstract": "  We have employed a penumbral model, that includes the Evershed flow and convective motions inside penumbral filaments, to reproduce the azimuthal variation of the net circular polarization (NCP) in sunspot penumbrae at different heliocentric angles for two different spectral lines. The theoretical net circular polarization fits the observations as satisfactorily as penumbral models based on flux-tubes. The reason for this is that the effect of convective motions on the NCP is very small compared to the effect of the Evershed flow. In addition, the NCP generated by convective upflows cancels out the NCP generated by the downflows. We have also found that, in order to fit the observed NCP, the strength of the magnetic field inside penumbral filaments must be very close to 1000 G. In particular, field-free or weak-field filaments fail to reproduce both the correct sign of the net circular polarization, as well as its dependence on the azimuthal and heliocentric angles. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0911/0911.2570v1.pdf"}
{"id": "0911.4749", "abstract": "  In this paper, we explore the parameter space for a Right-Handed (RH) sneutrino curvaton that can generate large non-Gaussianity without assuming any particular inflation sector. The mass of the RH sneutrino is suggested from a discussion on the initial condition of the curvaton field. It is shown that a small Yukawa coupling is generally required for a successful RH sneutrino curvaton. However, the Yukawa coupling can be larger if we consider the braneworld scenario. Some general discussion about the spectral index in curvaton scenario is also provided. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0911/0911.4749v1.pdf"}
{"id": "0912.3198", "abstract": "  We analyze the behavior of a quantum system described by a one-dimensional asymmetric potential consisting of a step plus a harmonic barrier. We solve the eigenvalue equation by the integral representation method, which allows us to classify the independent solutions as equivalence classes of homotopic paths in the complex plane. We then consider the propagation of a wave packet reflected by the harmonic barrier and obtain an expression for the interaction time as a function of the peak energy. For high energies we recover the classical half-period limit. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0912/0912.3198v2.pdf"}
{"id": "0912.4605", "abstract": "  Semi-analytic models of galaxy formation typically form the spheroidal components of galaxies (\"bulges\"), solely through galactic major mergers. However, it is possible that non-merger events (e.g. a \"fly-by\" by a smaller halo) can perturb a galaxy–halo system sufficiently to form a bulge. We present a preliminary investigation into the frequency of major changes in halo and galaxy spin direction, which could be signatures of such events. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0912/0912.4605v1.pdf"}
{"id": "1001.0060", "abstract": "  KLT relations on S_2 factorize closed string amplitudes into product of open string tree amplitudes. The field theory limits of KLT factorization relations hold in minimal coupling theory of gauge field and gravity. In this paper, we consider the field theory limits of relations on D_2. Though the relations on D_2 and KLT factorization relations hold on worldsheets with different topologies, we find the field theory limits of D_2 relations also hold in minimal coupling theory of gauge field and gravity. We use the D_2 relations to give three- and four-point tree amplitudes where gluons are minimally coupled to gravitons. We also give a discussion on general tree amplitudes for minimal coupling of gauge field and gravity. In general, any tree amplitude with M gravitons in addition to N gluons can be given by pure-gluon tree amplitudes with N+2M legs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1001/1001.0060v1.pdf"}
{"id": "1001.1640", "abstract": "  We discuss the relation between the fluctuation-dissipation relation derived by Chatelain and Ricci-Tersenghi [C.Chatelain, J.Phys. A 36, 10739 (2003); F. Ricci-Tersenghi, Phys.Rev.E 68, 065104(R) (2003)] and that by Lippiello-Corberi-Zannetti [E. Lippiello, F. Corberi and M. Zannetti Phys. Rev. E 72, 056103 (2005)]. In order to do that, we re-derive the fluctuation-dissipation relation for systems of discrete variables evolving in discrete time via a stochastic non-equilibrium Markov process. The calculation is carried out in a general formalism comprising the Chatelain, Ricci-Tersenghi result and that by Lippiello-Corberi-Zannetti as special cases. The applicability, generality, and experimental feasibility of the two approaches is thoroughly discussed. Extending the analytical calculation to the variance of the response function we show the vantage of field-free numerical methods with respect to the standard method where the perturbation is applied. We also show that the signal to noise ratio is better (by a factor √(2)) in the algorithm of Lippiello-Corberi-Zannetti with respect to that of Chatelain-Ricci Tersenghi. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1001/1001.1640v1.pdf"}
{"id": "1001.2339", "abstract": "  The static equilibrium deformation of a heavy spring due to its own weight is calculated for two cases. First for a spring hanging in a constant gravitational field, then for a spring which is at rest in a rotating system where it is stretched by the centrifugal force. Two different models are considered. First a discrete model assuming a finite number of point masses connected by springs of negligible weight. Then the continuum limit of this model. In the second case the differential equation for the deformation is obtained by demanding that the potential energy is minimized. In this way a simple application of the variational calculus is obtained. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1001/1001.2339v1.pdf"}
{"id": "1001.4669", "abstract": "  The squeezing dynamics of a damped harmonic oscillator are studied for different types of environment without making the Markovian approximation. The squeezing dynamics of a coherent state depend on the reservoir spectrum in a unique way that can, in the weak coupling approximation, be analyzed analytically. Comparison of squeezing dynamics for Ohmic, sub-Ohmic and super-Ohmic environments is done showing a clear connection between the squeezing–non-squeezing oscillations and reservoir structure. Understanding the effects occurring due to structured reservoirs is important both from a purely theoretical point of view and in connection with evolving experimental techniques and future quantum computing applications. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1001/1001.4669v1.pdf"}
{"id": "1002.2043", "abstract": "  We consider the high gain spontaneous parametric down-conversion in a non collinear geometry as a paradigmatic scenario to investigate the quantum-to-classical transition by increasing the pump power, that is, the average number of generated photons. The possibility of observing quantum correlations in such macroscopic quantum system through dichotomic measurement will be analyzed by addressing two different measurement schemes, based on different dichotomization processes. More specifically, we will investigate the persistence of non-locality in an increasing size n/2-spin singlet state by studying the change in the correlations form as n increases, both in the ideal case and in presence of losses. We observe a fast decrease in the amount of Bell's inequality violation for increasing system size. This theoretical analysis is supported by the experimental observation of macro-macro correlations with an average number of photons of about 10^3. Our results enlighten the practical extreme difficulty of observing non-locality by performing such a dichotomic fuzzy measurement. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.2043v2.pdf"}
{"id": "1003.0298", "abstract": "  We investigate acceptor and donor states in GaN nanocrystals doped with a single substitutional impurity. Quantum dots (QD's) of zinc-blende structure and spherical shape are considered with the radius ranging from 4.5 to 67.7 A. The size-dependent energy spectra are calculated within the sp3d5s* tight-binding model, which yields a good agreement with the confinement-induced blue shifts observed in undoped QD's. The computed binding energy is strongly enhanced with respect to the experimental bulk value when the dopant is placed at the center of the smallest QD's. It decreases with increasing QD size following a scaling law that extrapolates to the bulk limit. In order to estimate the degree of localization of the bound carriers we analyze their wave functions and average radii. The resulting physical picture points to a highly localized acceptor hole, mostly distributed over the nearest-neighbor anion shell, and a much more extended donor electron. We also study off-center impurities in intermediate-size QD's. The acceptor binding energy is approximately independent of the dopant position unless it is placed within a surface shell of thickness of the order of the bulk Bohr radius, where the ionization energy abruptly drops. On the contrary, the donor binding energy gradually decreases as the impurity is moved away from the center toward the QD surface. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.0298v1.pdf"}
{"id": "1003.1698", "abstract": "  Extra dimensions provide a very useful tool in addressing a number of the fundamental problems faced by the Standard Model. The following provides a very basic introduction to this very broad subject area as given at the VIII School of the Gravitational and Mathematical Physics Division of the Mexican Physical Society in December 2009. Some prospects for extra dimensional searches at the 7 TeV LHC with ∼1 fb^-1 of integrated luminosity are provided. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.1698v1.pdf"}
{"id": "1003.5785", "abstract": "  We propose a phenomenological model that describes counterflow and drag experiments with quantum Hall bilayers in a ν_T=1 state. We consider the system consisting of statistically distributed areas with local total filling factors ν_T1>1 and ν_T2<1. The excess or deficit of electrons in a given area results in an appearance of vortex excitations. The vortices in quantum Hall bilayers are charged. They are responsible for a decay of the exciton supercurrent, and, at the same time, contribute to the conductivity directly. The experimental temperature dependence of the counterflow and drive resistivities is described under accounting viscous forces applied to vortices that are the exponentially increase functions of the inverse temperature. The presence of defect areas where the interlayer phase coherence is destroyed completely can result in an essential negative longitudinal drag resistivity as well as in a counterflow Hall resistivity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.5785v1.pdf"}
{"id": "1004.2042", "abstract": "  Short Gamma-Ray Bursts (SGRBs) are expected to form from the coalescence of compact binaries, either of primordial origin or from dynamical interactions in globular clusters. In this paper, we investigate the possibility that the offset and afterglow brightness of a SGRB can help revealing the origin of its progenitor binary. We find that a SGRB is likely to result from the primordial channel if it is observed within 10 kpc from the center of a massive galaxy and shows a detectable afterglow. The same conclusion holds if it is 100 kpc away from a small, isolated galaxy and shows a weak afterglow. On the other hand, a dynamical origin is suggested for those SGRBs with observable afterglow either at a large separation from a massive, isolated galaxy or with an offset of 10-100 kpc from a small, isolated galaxy. We discuss the possibility that SGRBs from the dynamical channel are hosted in intra-cluster globular clusters and find that GRB 061201 may fall within this scenario. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.2042v1.pdf"}
{"id": "1004.2407", "abstract": "  We obtain systematic approximations to the states (energies and wave functions) of quantum rings (annular drums) of arbitrary shape by conformally mapping the annular domain to a simply connected domain. Extending the general results of Ref.<cit.> we obtain an analytical formula for the spectrum of quantum ring of arbirtrary shape: for the cases of a circular annulus and of a Robnik ring considered here this formula is remarkably simple and precise. We also obtain precise variational bounds for the ground state of different quantum rings. Finally we extend the Conformal Collocation Method of <cit.> to the class of problems considered here and calculate precise numerical solutions for a large number of states (≈ 2000). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.2407v1.pdf"}
{"id": "1005.0326", "abstract": "  The utility of chiral effective field theory, constructed in a manner in which loop contributions are suppressed as one moves outside the power-counting regime, is explored for baryon magnetic moments. Opportunities for the study of significant chiral curvature in valence and full QCD and the nontrivial behavior of strange- and light-quark contributions to the magnetic moment of the Lambda baryon are highlighted. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1005/1005.0326v1.pdf"}
{"id": "1005.1044", "abstract": "  Motivated by possible astrophysical and biological applications we calculate visible and near UV spectral lines of proflavine (C13H11N3, 3,6-diaminoacridine) in vacuum, as well as its anion, cation, and dication. The pseudopotential density functional and time-dependent density functional methods are used. We find a good agreement in spectral line positions calculated by two real-time propagation methods and the Lanczos chain method. Spectra of proflavine and its ions show characteristic UV lines which are good candidates for a detection of these molecules in interstellar space and various biological processes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1005/1005.1044v1.pdf"}
{"id": "1005.3792", "abstract": "  Spectra of the brightest blazars detected by the Fermi Gamma-ray Space Telescope Large Area Telescope cannot be described by a simple power law model. A much better description is obtained with a broken power law, with the break energies of a few GeV. We show here that the sharpness and the position of the breaks can be well reproduced by absorption of gamma-rays via photon–photon pair production on HeII Lyman recombination continuum and lines. This implies that the blazar zone lies inside the region of the highest ionization of the broad-line region (BLR) within a light-year from a super-massive black hole. The observations of gamma-ray spectral breaks open a way of studying the BLR photon field in the extreme-UV/soft X-rays, which are otherwise hidden from our view. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1005/1005.3792v2.pdf"}
{"id": "1005.5262", "abstract": "  We construct quantum games from a table of non-factorizable joint probabilities, coupled with a symmetry constraint, requiring symmetrical payoffs between the players. We give the general result for a Nash equilibrium and payoff relations for a game based on non-factorizable joint probabilities, which embeds the classical game. We study a quantum version of Prisoners' Dilemma, Stag Hunt, and the Chicken game constructed from a given table of non-factorizable joint probabilities to find new outcomes in these games. We show that this approach provides a general framework for both classical and quantum games without recourse to the formalism of quantum mechanics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1005/1005.5262v4.pdf"}
{"id": "1006.0324", "abstract": "  Guided by a study of kink-antikink scattering in the Gross-Neveu model and other known solutions of the Hartree-Fock approach of a particularly simple type, we demonstrate a quantitative relationship between three different problems: Quantized 1+1-dimensional fermions in the large N limit, solitons of the classical sinh-Gordon equation and classical strings moving in 3-dimensional anti de Sitter space. Aside from throwing light on the relationship between quantum field theory and classical physics, this points to the full solvability of the dynamical N-kink-antikink problem in the Gross-Neveu model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1006/1006.0324v1.pdf"}
{"id": "1006.1653", "abstract": "  The understanding of the interaction of nucleons in nuclear and neutron-rich matter at non-zero temperature is important for a variety of applications ranging from heavy-ion collisions to nuclear astrophysics. In this papre we apply the Dirac-Brueckner-Hartree-Fock method along with the Bonn B potential to predict single-particle properties in symmetric nuclear matter and neutron-rich matter at finite temperature. It is found that temperature effects are generally small but can be significant at low density and momentum. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1006/1006.1653v1.pdf"}
{"id": "1006.2946", "abstract": "  Hybrid quantum systems made of cold atoms near nanostructured surfaces are expected to open up new opportunities for the construction of quantum sensors and for quantum information. For the design of such tailored quantum systems the interaction of alkali atoms with dielectric and metallic surfaces is crucial and required to be understood in detail. Here, we present real-time measurements of the adsorption and desorption of Rubidium atoms on gold nanofilms. Surface plasmon polaritons (SPP) are excited at the gold surface and detected in a phase sensitive way. From the temporal change of the SPP phase the Rubidium coverage of the gold film is deduced with a sensitivity of better than 0.3 ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1006/1006.2946v1.pdf"}
{"id": "1006.3192", "abstract": "  We consider the effects of decoherence on the entanglement of photonic cluster states. Large photonic cluster states can be built by fusing together smaller photonic cluster states via probabilistic fusion operations. For this construction process it is necessary to store these smaller cluster states in some way so as to have them available for attempted fusion operations. While in storage the photonic cluster states may undergo dephasing. The effects of dephasing on small, primitive cluster states is explored here with the aim of determining how to locally rotate the qubits of the cluster state so as to lose the least amount of entanglement due to the dephasing process. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1006/1006.3192v1.pdf"}
{"id": "1006.3428", "abstract": "  In this letter we consider a correspondence between holographic dark energy and variable modified Chaplygin gas to obtain a holographic dark energy model of the universe. The corresponding potential of the scalar field has been reconstructed which describes the modified variable Chaplygin gas. The stability of the holographic dark energy in this case is also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1006/1006.3428v1.pdf"}
{"id": "1006.5550", "abstract": "  We review the T_90 duration and hardness ratio of Swift Gamma Ray Bursts (GRBs). We focus on GRBs with known redshift and review their gamma properties in the GRBs rest frames. We find that GRBs number vs. T_90/(1+z) distribution shows a separation between two classes at 0.65 s. Furthermore, we find that the difference in hardness ratio between short and long bursts is not very pronounced and depends on energy channels used for comparison. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1006/1006.5550v1.pdf"}
{"id": "1007.4020", "abstract": "  The dc voltage observed at low-temperatures in a 2D electron sample without external excitation is accounted by the Schottky contact rectification of the noise generated in the measuring circuit. The rectified voltage is shown to depend on the asymmetry of the contact pair. The dependence of the rectified voltage on the noise amplitude first follows the trivial quadratic law, then exhibits a nearly linear behavior, and, finally, levels-off. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1007/1007.4020v1.pdf"}
{"id": "1007.4830", "abstract": "  Single cell experiments of simple regulatory networks can markedly differ from cell population experiments. Such differences arise from stochastic events in individual cells that are averaged out in cell populations. For instance, while individual cells may show sustained oscillations in the concentrations of some proteins, such oscillations may appear damped in the population average. In this paper we investigate the role of RNA stochastic fluctuations as a leading force to produce a sustained excitatory behavior at the single cell level. Opposed to some previous models, we build a fully stochastic model of a negative feedback loop that explicitly takes into account the RNA stochastic dynamics. We find that messenger RNA random fluctuations can be amplified during translation and produce sustained pulses of protein expression. Motivated by the recent appreciation of the importance of non–coding regulatory RNAs in post–transcription regulation, we also consider the possibility that a regulatory RNA transcript could bind to the messenger RNA and repress translation. Our findings show that the regulatory transcript helps reduce gene expression variability both at the single cell level and at the cell population level. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1007/1007.4830v1.pdf"}
{"id": "1008.0752", "abstract": "  In this paper we present various convective states of zero-Prandtl number Rayleigh-Bénard convection using direct numerical simulations (DNS) and a 27-mode low-dimensional model containing the energetic modes of DNS. The origin of these convective states have been explained using bifurcation analysis. The system is chaotic at the onset itself with three coexisting chaotic attractors that are born at two codimension-2 bifurcation points. One of the bifurcation points with a single zero eigenvalue and a complex pair (0,± i ω) generates chaotic attractors and associated periodic, quasiperiodic, and phase-locked states that are related to the wavy rolls observed in experiments and simulations. The frequency of the wavy rolls are in general agreement with ω of the above eigenvalue of the stability matrix. The other bifurcation point with a double zero eigenvalue produces the other set of chaotic attractors and ordered states such as squares, asymmetric squares, oscillating asymmetric squares, relaxation oscillations with intermediate squares, some of which are common to the 13-mode model of Pal et al.(2009). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1008/1008.0752v1.pdf"}
{"id": "1008.4247", "abstract": "  We have calculated the kinematical correlations between charged leptons from semileptonic decays of open charm/bottom as well as leptons produced in the Drell-Yan mechanism in proton-proton collisions at BNL RHIC. Presented production rates for open charm and bottom were estimated by a detailed analysis of so-called nonphotonic electrons. The distributions for charm and bottom quarks pairs are calculated in the k_t-factorization approach with the help of the Kwieciński unintegrated parton distributions. The hadronization of heavy quarks is done by means of Peterson et al. fragmentation function. The semileptonic decay functions are found by fitting recent semileptonic data obtained by the CLEO and BABAR. We get good description of recent PHENIX data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1008/1008.4247v1.pdf"}
{"id": "1008.5195", "abstract": "  We propose phonon spectroscopy by electric measurements of the low-temperature conductance of coupled-quantum dots, specifically employing dephasing of the quantum electronic transport by the phonons. The setup we consider consists of a T-shaped double-quantum-dot (DQD) system in which only one of the dots (dot 1) is connected to external leads and the other (dot 2) is coupled solely to the first one. For noninteracting electrons, the differential conductance of such a system vanishes at a voltage located in-between the energies of the bonding and the anti-bonding states, due to destructive interference. When electron-phonon (e-ph) on the DQD is invoked, we find that, at low temperatures, phonon emission taking place on dot 1 does not affect the interference, while phonon emission from dot 2 suppresses it. The amount of this suppression, as a function of the bias voltage, follows the effective e-ph coupling reflecting the phonon density of states and can be used for phonon spectroscopy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1008/1008.5195v2.pdf"}
{"id": "1009.1647", "abstract": "  In this paper, we prove a limit set intersection theorem in relatively hyperbolic groups. Our approach is based on a study of dynamical quasiconvexity of relatively quasiconvex subgroups. Using dynamical quasiconvexity, many well-known results on limit sets of geometrically finite Kleinian groups are derived in general convergence groups. We also establish dynamical quasiconvexity of undistorted subgroups in finitely generated groups with nontrivial Floyd boundary. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.1647v3.pdf"}
{"id": "1009.1995", "abstract": "  The flows in and around sunspots are rich in detail. Starting with the Evershed flow along low-lying flow channels, which are cospatial with the horizontal penumbral magnetic fields, Evershed clouds may continue this motion at the periphery of the sunspot as moving magnetic features in the sunspot moat. Besides these well-ordered flows, peculiar motions are found in complex sunspots, where they contribute to the build-up or relaxation of magnetic shear. In principle, the three-dimensional structure of these velocity fields can be captured. The line-of-sight component of the velocity vector is accessible with spectroscopic measurements, whereas local correlation or feature tracking techniques provide the means to assess horizontal proper motions. The next generation of ground-based solar telescopes will provide spectropolarimetric data resolving solar fine structure with sizes below 50 km. Thus, these new telescopes with advanced post-focus instruments act as a \"zoom lens\" to study the intricate surface flows associated with sunspots. Accompanied by \"wide-angle\" observations from space, we have now the opportunity to describe sunspots as a system. This review reports recent findings related to flows in and around sunspots and highlights the role of advanced instrumentation in the discovery process. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.1995v1.pdf"}
{"id": "1009.2966", "abstract": "  Imaging systems based on a narrow-band tunable filter are used to obtain Doppler velocity maps of solar features. These velocity maps are created by taking the difference between the blue- and red-wing intensity images of a chosen spectral line. This method has the inherent assumption that these two images are obtained under identical conditions. With the dynamical nature of the solar features as well as the Earth's atmosphere, systematic errors can be introduced in such measurements. In this paper, a quantitative estimate of the errors introduced due to variable seeing conditions for ground-based observations is simulated and compared with real observational data for identifying their reliability. It is shown, under such conditions, that there is a strong cross-talk from the total intensity to the velocity estimates. These spurious velocities are larger in magnitude for the umbral regions compared to the penumbra or quiet-sun regions surrounding the sunspots. The variable seeing can induce spurious velocities up to about 1 km/s It is also shown that adaptive optics, in general, helps in minimising this effect. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.2966v1.pdf"}
{"id": "1009.3847", "abstract": "  Different stoichiometric configurations of graphane and graphene fluoride are investigated within density functional theory. Their structural and electronic properties are compared, and we indicate the similarities and differences among the various configurations. Large differences between graphane and graphene fluoride are found that are caused by the presence of charges on the fluorine atoms. A new configuration that is more stable than the boat configuration is predicted for graphene fluoride. We also perform GW calculations for the electronic band gap of both graphene derivatives. These band gaps and also the calculated Young's moduli are at variance with available experimental data. This might indicate that the experimental samples contain a large number of defects or are only partially covered with H or F. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.3847v1.pdf"}
{"id": "1011.1035", "abstract": "  The problem of identifying the 3D pose of a known object from a given 2D image has important applications in Computer Vision ranging from robotic vision to image analysis. Our proposed method of registering a 3D model of a known object on a given 2D photo of the object has numerous advantages over existing methods: It does neither require prior training nor learning, nor knowledge of the camera parameters, nor explicit point correspondences or matching features between image and model. Unlike techniques that estimate a partial 3D pose (as in an overhead view of traffic or machine parts on a conveyor belt), our method estimates the complete 3D pose of the object, and works on a single static image from a given view, and under varying and unknown lighting conditions. For this purpose we derive a novel illumination-invariant distance measure between 2D photo and projected 3D model, which is then minimised to find the best pose parameters. Results for vehicle pose detection are presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1011/1011.1035v1.pdf"}
{"id": "1011.4701", "abstract": "  We discuss the effect of chemical separation as matter freezes at the base of the ocean of an accreting neutron star, and argue that the retention of light elements in the liquid acts as a source of buoyancy that drives a slow but continual mixing of the ocean, enriching it substantially in light elements, and leading to a relatively uniform composition with depth. We first consider the timescales associated with different processes that can redistribute elements in the ocean, including convection, sedimentation, crystallization, and diffusion. We then calculate the steady state structure of the ocean of a neutron star for an illustrative model in which the accreted hydrogen and helium burns to produce a mixture of O and Se. Even though the H/He burning produces only 2", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1011/1011.4701v1.pdf"}
{"id": "1011.5673", "abstract": "  In this paper we study the effects of the Generalized Uncertainty Principle (GUP) on the spectrum of a particle that is bouncing vertically and elastically on a smooth reflecting floor in the Earth's gravitational field (a quantum bouncer). We calculate energy levels and corresponding wave functions of this system in terms of the GUP parameter. We compare the outcomes of our study with the results obtained from elementary quantum mechanics. A potential application of the present study is discussed finally. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1011/1011.5673v1.pdf"}
{"id": "1101.4098", "abstract": "  A new method to constrain the distance of blazars with unknown redshift using combined observations in the GeV and TeV regimes will be presented. The underlying assumption is that the Very High Energy (VHE) spectrum corrected for the absorption of TeV photons by the Extragalactic Background Light (EBL) via photon-photon interaction should still be softer than the extrapolation of the gamma-ray spectrum observed by Fermi/LAT. Starting from the observed spectral data at VHE, the EBL-corrected spectra are derived as a function of the redshift z and fitted with power laws. Comparing the redshift dependent VHE slopes with the power law fits to the LAT data an upper limit to the source redshift can be derived. The method is applied to all TeV blazars detected by LAT with known distance and an empirical law describing the relation between the upper limits and the true redshifts is derived. This law can be used to estimate the distance of unknown redshift blazars: as an example, the distance of PKS 1424+240 is inferred. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1101/1101.4098v1.pdf"}
{"id": "1101.5918", "abstract": "  This paper continues a previous study of neutron stars with positive polar-cap corotational charge density in which free emission of ions maintains the surface electric-field boundary condition E.B = 0. The composition of the accelerated plasma on any subset of open magnetic flux-lines above the polar cap alternates between two states; either protons or positrons and ions, of which the proton state cannot support electron-positron pair creation at higher altitudes. The two states coexist at any instant of time above different moving elements of area on the polar cap and provide a physically consistent basis for a description of pulse nulls and sub-pulse drift. In the latter case, it is shown that the band separation P3 is determined not by the ExB drift velocity, as is generally assumed, but by the diffusion time for protons produced in reverse-electron showers to reach the region of the atmosphere from which they are accelerated. An initial comparison is made with the survey of sub-pulse drift published by Weltevrede et al. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1101/1101.5918v1.pdf"}
{"id": "1102.0868", "abstract": "  We performed numerical simulations of the obliquity evolution of Mars during the Noachian era, at which time the giant planets were on drastically different orbits than today. For the preferred primordial configuration of the planets we find that there are two large zones where the Martian obliquity is stable and oscillates with an amplitude lower than 20^∘. These zones occur at obliquities below 30^∘ and above 60^∘; intermediate values show either resonant or chaotic behaviour depending on the primordial orbits of the terrestrial planets. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.0868v1.pdf"}
{"id": "1102.2841", "abstract": "  We work out the graph limit theory for dense interval graphs. The theory developed departs from the usual description of a graph limit as a symmetric function W(x,y) on the unit square, with x and y uniform on the interval (0,1). Instead, we fix a W and change the underlying distribution of the coordinates x and y. We find choices such that our limits are continuous. Connections to random interval graphs are given, including some examples. We also show a continuity result for the chromatic number and clique number of interval graphs. Some results on uniqueness of the limit description are given for general graph limits. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.2841v1.pdf"}
{"id": "1102.3618", "abstract": "  Cubic sevenfolds are examples of Fano manifolds of Calabi-Yau type. We study them in relation with the Cartan cubic, the E_6-invariant cubic in ^26. We show that a generic cubic sevenfold X can be described as a linear section of the Cartan cubic, in finitely many ways. To each such \"Cartan representation\" we associate a rank nine vector bundle on X with very special cohomological properties. In particular it allows to define auto-equivalences of the non-commutative Calabi-Yau threefold associated to X by Kuznetsov. Finally we show that the generic eight dimensional section of the Cartan cubic is rational. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.3618v2.pdf"}
{"id": "1103.1236", "abstract": "  We propose to test the theory of continuous spontaneous localization (CSL) in an all-optical time-domain Talbot-Lau interferometer for clusters with masses exceeding 1000000 amu. By assessing the relevant environmental decoherence mechanisms, as well as the growing size of the particles relative to the grating fringes, we argue that it will be feasible to test the quantum superposition principle in a mass range excluded by recent estimates of the CSL effect. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.1236v2.pdf"}
{"id": "1103.1465", "abstract": "  The polarized antiquark distributions in the proton can be measured by studying spin asymmetries in vector boson production in longitudinally polarized proton-proton collisions. The STAR and PHENIX experiments at BNL RHIC have reported first observations of single spin asymmetries in W^±-production most recently. We compute the QCD corrections to single and double spin asymmetries, taking account of the leptonic decay of the W^± boson and of restrictions on the kinematical acceptance of the detectors. The QCD corrections have only a small impact on the asymmetries, such that a reliable extraction of the polarized antiquark distributions can be envisaged once more precise measurements are made. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.1465v2.pdf"}
{"id": "1103.1518", "abstract": "  Tor is a popular low-latency anonymity network. However, Tor does not protect against the exploitation of an insecure application to reveal the IP address of, or trace, a TCP stream. In addition, because of the linkability of Tor streams sent together over a single circuit, tracing one stream sent over a circuit traces them all. Surprisingly, it is unknown whether this linkability allows in practice to trace a significant number of streams originating from secure (i.e., proxied) applications. In this paper, we show that linkability allows us to trace 193", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.1518v1.pdf"}
{"id": "1103.2320", "abstract": "  We investigate a model for the CuO_2 plane of high-T_c superconductors where the charge carriers are coupled to A_1g and B_1g symmetric out-of plane vibrations of the oxygen atoms in the presence of local Hubbard correlations. The coupling is implemented via a modulation of the hopping integral and we calculate the renormalization of vertex and pairing scattering functions based on the time-dependent Gutziller approximation. Contrary to local electron-phonon couplings we find that the transitive coupling can even be enhanced by correlations for certain momenta and symmetries of the vibrations. While this effect may be important for certain properties, we find that, with regard to superconductivity, electron-electron correlations still generically lead to a suppression of the pairing correlations. Our results allow for an estimate of correlation effects on the electron-phonon induced pair scattering from weak electron-electron interactions up to the Mott regime. For onsite repulsions relevant to cuprate superconductors our calculations reveal a significant contribution of B_1g phonons to d-wave superconductivity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.2320v1.pdf"}
{"id": "1103.3189", "abstract": "  We present a reliable algorithm to evaluate quantum discord for general two–qubit states, amending and extending an approach recently put forward for the subclass of X–states. A closed expression for the discord of arbitrary states of two qubits cannot be obtained, as the optimization problem for the conditional entropy requires the solution to a pair of transcendental equations in the state parameters. We apply our algorithm to run a numerical comparison between quantum discord and an alternative, computable measure of non-classical correlations, namely the geometric discord. We identify the extremally non-classically correlated two–qubit states according to the (normalized) geometric discord, at fixed value of the conventional quantum discord. The latter cannot exceed the square root of the former for systems of two qubits. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.3189v2.pdf"}
{"id": "1103.4285", "abstract": "  The isotopic evolution of the ground-state nuclear shapes and the systematics of one-quasiproton configurations are studied in neutron-rich odd-A Yttrium and Niobium isotopes. We use a selfconsistent Hartree-Fock-Bogoliubov formalism based on the Gogny energy density functional with two parametrizations, D1S and D1M. The equal filling approximation is used to describe odd-A nuclei preserving both axial and time reversal symmetries. Shape-transition signatures are identified in the N=60 isotopes in both charge radii and spin-parities of the ground states. These signatures are a common characteristic for nuclei in the whole mass region. The nuclear deformation and shape coexistence inherent to this mass region are shown to play a relevant role in the understanding of the spectroscopic features of the ground and low-lying one-quasiproton states. Finally, a global picture of the neutron-rich A=100 mass region from Krypton up to Molybdenum isotopes is illustrated with the systematics of the nuclear charge radii isotopic shifts. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.4285v1.pdf"}
{"id": "1104.0387", "abstract": "  During the inspiral and merger of black holes, the interaction of gravitational wave multipoles carries linear momentum away, thereby providing an astrophysically important recoil, or \"kick\" to the system and to the final black hole remnant. It has been found that linear momentum during the last stage (quasinormal ringing) of the collapse tends to provide an \"antikick\" that in some cases cancels almost all the kick from the earlier (quasicircular inspiral) emission. We show here that this cancellation is not due to peculiarities of gravitational waves, black holes, or interacting multipoles, but simply to the fact that the rotating flux of momentum changes its intensity slowly. We show furthermore that an understanding of the systematics of the emission allows good estimates of the net kick for numerical simulations started at fairly late times, and is useful for understanding qualitatively what kinds of systems provide large and small net kicks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1104/1104.0387v1.pdf"}
{"id": "1104.4519", "abstract": "  HESS J0632+057 is a variable, point-like source of Very High Energy (>100 GeV) gamma-rays located in the Galactic plane. It is positionally coincident with a Be star, it is a variable radio and X-ray source, has a hard X-ray spectrum, and has low radio flux. These properties suggest that the object may be a member of the rare class of TeV/X-ray binary systems. The definitive confirmation of this would be the detection of a periodic orbital modulation of the flux at any wavelength. We have obtained Swift X-ray telescope observations of the source from MJD 54857 to 55647 (Jan. 2009 - Mar. 2011) to test the hypothesis that HESS J0632+057 is an X-ray/TeV binary. We show that these data exhibit flux modulation with a period of 321 ± 5 days and we evaluate the significance of this period by calculating the null hypothesis probability, allowing for stochastic flaring. This periodicity establishes the binary nature of HESS J0632+057. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1104/1104.4519v2.pdf"}
{"id": "1104.4801", "abstract": "  We report on the discovery by the Swift Gamma-Ray Burst Explorer of the black hole candidate Swift J1539.2-6227 and the subsequent course of an outburst beginning in November 2008 and lasting at least seven months. The source was discovered during normal observations with the Swift Burst Alert Telescope (BAT) on 2008 November 25. An extended observing campaign with the Rossi X-Ray Timing Explorer (RXTE) and Swift provided near-daily coverage over 176 days, giving us a good opportunity to track the evolution of spectral and timing parameters with fine temporal resolution through a series of spectral states. The source was first detected in a hard state during which strong low-frequency quasi-periodic oscillations (QPOs) were detected. The QPOs persisted for about 35 days and a signature of the transition from the hard to soft intermediate states was seen in the timing data. The source entered a short-lived thermal state about 40 days after the start of the outburst. There were variations in spectral hardness as the source flux declined and returned to a hard state at the end of the outburst. The progression of spectral states and the nature of the timing features provide strong evidence that Swift J1539.2-6227 is a candidate black hole in a low-mass X-ray binary system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1104/1104.4801v1.pdf"}
{"id": "1104.5446", "abstract": "  Two relativistic approaches are considered to evaluate the quasielastic double-differential and integrated neutrino-nucleus cross sections. One, based on the relativistic impulse approximation, relies on the microscopic description of nuclear dynamics using relativistic mean field theory, and incorporates a description of the final-state interactions. The second is based on the superscaling behavior exhibited by electron scattering data and its applicability, due to the universal character of the scaling function, to the analysis of neutrino scattering reactions. The role played by the vector meson-exchange currents in the two-particle two-hole sector is also incorporated and the results obtained are compared with the recent data for neutrinos measured by the MiniBooNE Collaboration. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1104/1104.5446v1.pdf"}
{"id": "1105.2474", "abstract": "  In this paper we study the shape differentiability properties of a class of boundary integral operators and of potentials with weakly singular pseudo-homogeneous kernels acting between classical Sobolev spaces, with respect to smooth deformations of the boundary. We prove that the boundary integral operators are infinitely differentiable without loss of regularity. The potential operators are infinitely shape differentiable away from the boundary, whereas their derivatives lose regularity near the boundary. We study the shape differentiability of surface differential operators. The shape differentiability properties of the usual strongly singular or hypersingular boundary integral operators of interest in acoustic, elastodynamic or electromagnetic potential theory can then be established by expressing them in terms of integral operators with weakly singular kernels and of surface differential operators. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.2474v2.pdf"}
{"id": "1105.2511", "abstract": "  Nonequilibrium molecular dynamics simulations is used to study the motion of a C60 molecule on a graphene sheet subjected to a temperature gradient. The C60 molecule is actuated and moves along the system while it just randomly dances along the perpendicular direction. Increasing the temperature gradient increases the directed velocity of C60. It is found that the free energy decreases as the C60 molecule moves toward the cold end. The driving mechanism based on the temperature gradient suggests the construction of nanoscale graphene-based motors. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.2511v1.pdf"}
{"id": "1105.2640", "abstract": "  We define a conjugate prior for the reversible Markov chain of order r. The prior arises from a partially exchangeable reinforced random walk, in the same way that the Beta distribution arises from the exchangeable Polyá urn. An extension to variable-order Markov chains is also derived. We show the utility of this prior in testing the order and estimating the parameters of a reversible Markov model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.2640v1.pdf"}
{"id": "1105.4623", "abstract": "  We construct a 3-3-1 model for three families that can be embedded into a single SU(8) unified model. Assuming appropriate branching rules and symmetry-breaking pattern, we find a complete fermion content within irreducible representations of SU(8), where light standard model fermions, heavy 3-3-1 fermions and super-heavy fermions may be distinguished. In the framework of the doubly lopsided mechanism, we obtain mass matrix structures which exhibit nontrivial flavor hierarchical features. Among the up-type quarks, one (top quark) has tree-level mass and two (charm and up) get masses at one-loop level. Considering only dominant contributions, we may obtain the ratios |m_c/m_t| ≈ 7.4 × 10^-3 and |m_u/m_c| ≈ 1.9 × 10^-3 with few assumptions on the free parameters and without any hierarchical requirements on the Yukawa couplings. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.4623v1.pdf"}
{"id": "1105.5862", "abstract": "  We systematically explore and show the existence of finite-temperature continuous quantum phase transition (CTQPT) at a critical point, namely, during solidification or melting such that the first-order thermal phase transition is a special case within CTQPT. Infact, CTQPT is related to chemical reaction where quantum fluctuation (due to wavefunction transformation) is caused by thermal energy and it can occur maximally for temperatures much higher than zero Kelvin. To extract the quantity related to CTQPT, we use the ionization energy theory and the energy-level spacing renormalization group method to derive the energy-level spacing entropy, renormalized Bose-Einstein distribution and the time-dependent specific heat capacity. This work unambiguously shows that the quantum phase transition applies for any finite temperatures. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.5862v7.pdf"}
{"id": "1107.0950", "abstract": "  Graphene physisorbed on a metal has its characteristic Dirac cones preserved in the band-structure, but the Fermi level of the system is shifted due to the interaction with the substrate. Based on density functional calculations with van der Waals corrections, we present a method to determine the position of the Dirac point with respect to the Fermi level from the measured scanning tunneling spectra (STS). It has been demonstrated that the dips in both simulated local density of states and in the observed dI/dV profiles are indeed the fingerprints of the Dirac points. The type and the level of doping can be then inferred directly from the STS data without any additional experimental technique. Test calculations of graphene on a Cu(111) substrate have shown that the predicted position of the Dirac point is in close proximity to the experimental value reported in the recent studies. Moreover, simulations for graphene on a Pt(111) surface allow us to explain the apparent contradictions in the state-of-the-art experimental works. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.0950v2.pdf"}
{"id": "1107.1900", "abstract": "  Understanding the structure and evolution of web-based user-object bipartite networks is an important task since they play a fundamental role in online information filtering. In this paper, we focus on investigating the patterns of online users' behavior and the effect on recommendation process. Empirical analysis on the e-commercial systems show that users have significant taste diversity and their interests for niche items highly overlap. Additionally, recommendation process are investigated on both the real networks and the reshuffled networks in which real users' behavior patterns can be gradually destroyed. Our results shows that the performance of personalized recommendation methods is strongly related to the real network structure. Detail study on each item shows that recommendation accuracy for hot items is almost maximum and quite robust to the reshuffling process. However, niche items cannot be accurately recommended after removing users' behavior patterns. Our work also is meaningful in practical sense since it reveals an effective direction to improve the accuracy and the robustness of the existing recommender systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.1900v1.pdf"}
{"id": "1107.2599", "abstract": "  Theory and simulations suggest that magnetic fields from radio jets and lobes powered by their central super massive black holes can be an important source of magnetic fields in the galaxy clusters. This is paper II in a series of studies where we present self-consistent high-resolution adaptive mesh refinement cosmological magnetohydrodynamic (MHD) simulations that simultaneously follow the formation of a galaxy cluster and evolution of magnetic fields ejected by an active galactic nucleus (AGN). We studied 12 different galaxy clusters with virial masses ranging from 1 × 10^14 to 2 × 10^15 M_⊙. In this work we examine the effects of the mass and merger history on the final magnetic properties. We find that the evolution of magnetic fields is qualitatively similar to those of previous studies. In most clusters, the injected magnetic fields can be transported throughout the cluster and be further amplified by the intra-cluster medium (ICM) turbulence during the cluster formation process with hierarchical mergers, while the amplification history and the magnetic field distribution depend on the cluster formation and magnetism history. This can be very different for different clusters. The total magnetic energies in these clusters are between 4 × 10^57 and 10^61 erg, which is mainly decided by the cluster mass, scaling approximately with the square of the total mass. Dynamically older relaxed clusters usually have more magnetic fields in their ICM. The dynamically very young clusters may be magnetized weakly since there is not enough time for magnetic fields to be amplified. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.2599v2.pdf"}
{"id": "1108.0754", "abstract": "  The Burning Index (BI) produced daily by the United States government's National Fire Danger Rating System is commonly used in forecasting the hazard of wildfire activity in the United States. However, recent evaluations have shown the BI to be less effective at predicting wildfires in Los Angeles County, compared to simple point process models incorporating similar meteorological information. Here, we explore the forecasting power of a suite of more complex point process models that use seasonal wildfire trends, daily and lagged weather variables, and historical spatial burn patterns as covariates, and that interpolate the records from different weather stations. Results are compared with models using only the BI. The performance of each model is compared by Akaike Information Criterion (AIC), as well as by the power in predicting wildfires in the historical data set and residual analysis. We find that multiplicative models that directly use weather variables offer substantial improvement in fit compared to models using only the BI, and, in particular, models where a distinct spatial bandwidth parameter is estimated for each weather station appear to offer substantially improved fit. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.0754v1.pdf"}
{"id": "1108.1561", "abstract": "  We consider the following generalization of the classical pursuit-evasion problem, which we call k-capture. A group of n pursuers (hyenas) wish to capture an evader (lion) who is free to move in an m-dimensional Euclidean space, the pursuers and the evader can move with the same maximum speed, and at least k pursuers must simultaneously reach the evader's location to capture it. If fewer than k pursuers reach the evader, then those pursuers get destroyed by the evader. Under what conditions can the evader be k-captured? We study this problem in the discrete time, continuous space model and prove that k-capture is possible if and only there exists a time when the evader lies in the interior of the pursuers' k-Hull. When the pursuit occurs inside a compact, convex subset of the Euclidean space, we show through an easy constructive strategy that k-capture is always possible. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.1561v1.pdf"}
{"id": "1108.3000", "abstract": "  We compute all isomorphism classes of simplicial arrangements in the real projective plane with up to 27 lines. It turns out that Grünbaums catalogue is complete up to 27 lines except for four new arrangements with 22, 23, 24, 25 lines, respectively. As a byproduct we classify simplicial arrangements of pseudolines with up to 27 lines. In particular, we disprove Grünbaums conjecture about unstretchable arrangements with at most 16 lines, and prove the conjecture that any simplicial arrangement with at most 14 pseudolines is stretchable. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.3000v1.pdf"}
{"id": "1108.3226", "abstract": "  The paper investigates consensus problem for continuous-time multi-agent systems with time-varying communication graphs subject to process noises. Borrowing the ideas from input-to-state stability (ISS) and integral input-to-state stability (iISS), robust consensus and integral robust consensus are defined with respect to L_∞ and L_1 norms of the disturbance functions, respectively. Sufficient and/or necessary connectivity conditions are obtained for the system to reach robust consensus or integral robust consensus, which answer the question: how much communication capacity is required for a multi-agent network to converge despite certain amount of disturbance. The ϵ-convergence time is then obtained for the network as a special case of the robustness analysis. The results are based on quite general assumptions on switching graph, weights rule and noise regularity. In addition, as an illustration of the applicability of the results, distributed event-triggered coordination is studied. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.3226v2.pdf"}
{"id": "1108.4046", "abstract": "  We study localized plasmons at the nanoscale (nano-plasmons) in graphene. The collective excitations of induced charge density modulations in graphene are drastically changed in the vicinity of a single impurity compared to graphene's bulk behavior. The dispersion of nano-plasmons depends on the number of electrons and the sign, strength and size of the impurity potential. Due to this rich parameter space the calculated dispersions are intrinsically multidimensional requiring an advanced visualization tool for their efficient analysis, which can be achieved with parallel rendering. To overcome the problem of analyzing thousands of very complex spatial patterns of nano-plasmonic modes, we take a combined visual and quantitative approach to investigate the excitations on the two-dimensional graphene lattice. Our visual and quantitative analysis shows that impurities trigger the formation of localized plasmonic excitations of various symmetries. We visually identify dipolar, quadrupolar and radial modes, and quantify the spatial distributions of induced charges. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.4046v1.pdf"}
{"id": "1108.5283", "abstract": "  To unambiguously identify baryon resonances the measurement of polarization observables is of great importance. With the CBELSA/TAPS experiment, located at the ELSA accelerator facility in Bonn, polarization observables have been determined. Using a linearly polarized photon beam impinging on a liquid hydrogen target, the polarization observables I^s and I^c for the reaction γp -> p π^0 π^0 have been determined for the first time. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.5283v1.pdf"}
{"id": "1108.6057", "abstract": "  We investigate the 1D Anderson-Hubbard model at half filling with box-disorder. The ground state phase diagram is obtained by means of real-space dynamical mean-field theory (R-DMFT) and the density matrix renormalization group (DMRG). We find Mott insulating and Anderson localized regimes as well as a strong indication of a delocalized phase for intermediate interaction and disorder strength within accessible system sizes. These phases are characterized and distinguished by qualitatively different scaling behavior of the local density of states, the energy gap in the excitation spectrum and the inverse participation number. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.6057v1.pdf"}
{"id": "1109.0063", "abstract": "  We study the magnetization plateau state of the three-leg spin-1/2 tube in the strong rung coupling region, where S_3-symmetry breakings and low-energy chirality degree of freedom play crucial roles. On the basis of the effective chirality model and density matrix renormalization group, we clarify that, as the leg coupling increases, the chirality liquid with gapless non-magnetic excitations, the spin imbalance phase and the vector-spin-chirality ordered phase emerge without closing the plateau spin gap. The relevance of these results to experiments is also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1109/1109.0063v2.pdf"}
{"id": "1109.4320", "abstract": "  The results of an adaptive optics survey of exoplanet host stars for stellar companions is presented. We used the AEOS Telescope and its adaptive optics system to collect deep images of the stars in I-band. Sixty-two exoplanet host stars were observed and fifteen multiple star systems were resolved. Of these eight are known multiples, while seven are new candidate binaries. For all binaries, we measured the relative astrometry of the pair and the differential magnitude in I-band. We improved the orbits of HD 19994 and τ Boo. These observations will provide improved statistics on the duplicity of exoplanet hosts stars and provide an increased understanding of the dynamics of known binary star exoplanet hosts. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1109/1109.4320v1.pdf"}
{"id": "1110.2042", "abstract": "  There is considerable experimental effort dedicated to the directional detection of particle dark matter. Gaseous mu-TPC detectors present the privileged features of being able to reconstruct the track and the energy of the recoil nucleus following the interaction. A precise measurement of the recoil energy is a key point for the directional search strategy. Quenching has to be taken into account, i.e. only a certain fraction of the recoil energy is deposited in the ionization channel. Measurements of the ionization quenching factor for different gas mixture at room temperature have been made with a dedicated ion beam facility at the LPSC of Grenoble. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.2042v1.pdf"}
{"id": "1110.4459", "abstract": "  We study random walks on a family of treelike regular fractals with a trap fixed on a central node. We obtain all the eigenvalues and their corresponding multiplicities for the associated stochastic master equation, with the eigenvalues being provided through an explicit recursive relation. We also evaluate the smallest eigenvalue and show that its reciprocal is approximately equal to the mean trapping time. We expect that our technique can also be adapted to other regular fractals with treelike structures. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.4459v1.pdf"}
{"id": "1110.6875", "abstract": "  The Causal Dynamical Triangulation (CDT) approach to quantum gravity is a lattice approximation to the gravitational path integral. Developed by Ambjørn, Jurkiewicz and Loll, it has yielded some important results, notably the emergence of classical spacetime and short scale dimensional reduction. However, virtually all the results reported so far have been based on a single computer code. In this paper we present the first completely independent verification of the CDT algorithm, and report the successful reproduction of the emergence of classical spacetime and smooth reduction in the spectral dimension of the 2+1 and 3+1 dimensional spacetimes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.6875v2.pdf"}
{"id": "1111.0010", "abstract": "  We explore the chemical structure of a disk that contains a large central gap of R   45 AU, as is commonly seen in transitional disk systems. In our chemical model of a disk with a cleared inner void, the midplane becomes revealed to the central star so that it is directly irradiated. The midplane material at the truncation radius is permissive to reprocessed optical heating radiation, but opaque to the photo-dissociating ultraviolet, creating an environment abundant in gas-phase molecules. Thus the disk midplane, which would otherwise for a full disk be dominated by near complete heavy element freeze-out, should become observable in molecular emission. If this prediction is correct this has exciting prospects for observations with the Atacama Large Millimeter/Submillimeter Array (ALMA), as the inner transition region should thus be readily detected and resolved, especially using high-J rotational transitions excited in the high density midplane gas. Therefore such observations will potentially provide us with a direct probe of the physics and chemistry at this actively evolving interface. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.0010v1.pdf"}
{"id": "1111.0970", "abstract": "  We present a set of numerical simulations of stellar explosions induced by relativistic jets emanating from a central engine sitting at the center of compact, dying stars. We explore a wide range of durations of the central engine activity, two candidate stellar progenitors, and two possible values of the total energy release. We find that even if the jets are narrowly collimated, their interaction with the star unbinds the stellar material, producing a stellar explosion. We also find that the outcome of the explosion can be very different depending on the duration of the engine activity. Only the longest-lasting engines result in successful gamma-ray bursts. Engines that power jets only for a short time result in relativistic supernova explosions, akin to observed engine-driven SNe such as SN2009bb. Engines with intermediate durations produce weak gamma-ray bursts, with properties similar to nearby bursts such as GRB 980425. Finally, we find that the engines with the shortest durations, if they exist in nature, produce stellar explosions that lack sizable amounts of relativistic ejecta and are therefore dynamically indistinguishable from ordinary core-collapse supernovae. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.0970v2.pdf"}
{"id": "1111.5026", "abstract": "  Electronic energy transfer in the condensed phase, such as that occurring in photosynthetic complexes, frequently occurs in regimes where the energy scales of the system and environment are similar. This situation provides a challenge to theoretical investigation since most approaches are accurate only when a certain energetic parameter is small compared to others in the problem. Here we show that in these difficult regimes, the Ehrenfest approach provides a good starting point for a dynamical description of the energy transfer process due to its ability to accurately treat coupling to slow environmental modes. To further improve on the accuracy of the Ehrenfest approach, we use our reduced density matrix hybrid framework to treat the faster environmental modes quantum mechanically, at the level of a perturbative master equation. This combined approach is shown to provide an efficient and quantitative description of electronic energy transfer in a model dimer and the Fenna-Matthews-Olson complex and is used to investigate the effect of environmental preparation on the resulting dynamics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.5026v1.pdf"}
{"id": "1111.6308", "abstract": "  In this paper linear canonical correlation analysis (LCCA) is generalized by applying a structured transform to the joint probability distribution of the considered pair of random vectors, i.e., a transformation of the joint probability measure defined on their joint observation space. This framework, called measure transformed canonical correlation analysis (MTCCA), applies LCCA to the data after transformation of the joint probability measure. We show that judicious choice of the transform leads to a modified canonical correlation analysis, which, in contrast to LCCA, is capable of detecting non-linear relationships between the considered pair of random vectors. Unlike kernel canonical correlation analysis, where the transformation is applied to the random vectors, in MTCCA the transformation is applied to their joint probability distribution. This results in performance advantages and reduced implementation complexity. The proposed approach is illustrated for graphical model selection in simulated data having non-linear dependencies, and for measuring long-term associations between companies traded in the NASDAQ and NYSE stock markets. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.6308v3.pdf"}
{"id": "1111.6512", "abstract": "  In this work, we present a novel analytical model for tracer dispersion in laminar flow through porous media. Based on a straightforward physical argument, it describes the generic behavior of dispersion over a wide range of Peclet numbers (exceeding 8 orders of magnitude). In particular, the model accurately captures the intermediate scaling behavior of longitudinal dispersion, obviating the need to subdivide the dispersional behavior into a number of disjunct regimes or using empirical power law expressions.   The analysis also reveals the existence of a new material property, the critical Peclet number, which reflects the mesoscale geometric properties of the microscopic pore structure. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.6512v2.pdf"}
{"id": "1112.0003", "abstract": "  We study the effect of color octet scalars on the high transverse momenta four-jet cross section at the LHC. We consider both weak singlet and doublet scalars, concentrating on the case of small couplings to quarks. We find that a relatively early discovery at the LHC is possible for a range of scalar masses. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.0003v1.pdf"}
{"id": "1112.0622", "abstract": "  We investigate the feasibility of implementing a system that will coordinate ground-based optical telescopes to cover the Fermi GBM Error Circle (EC). The aim of the system is to localize GBM detected GRBs and facilitate multi-wavelength follow-up from space and ground. This system will optimize the observing locations in the GBM EC based on individual telescope location, Field of View (FoV) and sensitivity. The proposed system will coordinate GBM EC scanning by professional as well as amateur astronomers around the world. The results of a Monte Carlo simulation to investigate the feasibility of the project are presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.0622v1.pdf"}
{"id": "1112.0647", "abstract": "  We prove three conjectures concerning the evaluation of determinants, which are related to the counting of plane partitions and rhombus tilings. One of them was posed by George Andrews in 1980, the other two were by Guoce Xin and Christian Krattenthaler. Our proofs employ computer algebra methods, namely, the holonomic ansatz proposed by Doron Zeilberger and variations thereof. These variations make Zeilberger's original approach even more powerful and allow for addressing a wider variety of determinants. Finally, we present, as a challenge problem, a conjecture about a closed-form evaluation of Andrews's determinant. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.0647v3.pdf"}
{"id": "1112.3562", "abstract": "  We use numerically exact diagonalization to calculate the spin-orbit and phonon-induced triplet-singlet relaxation rate in a two-electron quantum dot exposed to a tilted magnetic field. Our scheme includes a three-dimensional description of the quantum dot, the Rashba and the linear and cubic Dresselhaus spin-orbit coupling, the ellipticity of the quantum dot, and the full angular description of the magnetic field. We are able to find reasonable agreement with the experimental results of Meunier et al. [Phys. Rev. Lett. 98, 126601 (2007)] in terms of the singlet-triplet energy splitting and the spin relaxation rate, respectively. We analyze in detail the effects of the spin-orbit factors, magnetic-field angles, and the dimensionality, and discuss the origins of the remaining deviations from the experimental data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.3562v1.pdf"}
{"id": "1112.4211", "abstract": "  We are extending our search for faint PNe in the LMC to include the outer 56 deg2 area not covered in the original UKST survey of the central 25 deg2 region. Candidate PNe have been selected using the Magellanic Cloud Emission Line Survey (MCELS) and the first round of observations has yielded 93 new LMC PNe while confirming the 102 previously known PNe in the outer LMC. We plan to continue our spectroscopic object identification program until we cover all our remaining candidates in the survey area. These observations, providing medium and high resolution spectra from 3650 Ang to 6900 Ang will additionally be used to measure fluxes for a series of research projects including luminosity functions, abundances and LMC kinematics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.4211v1.pdf"}
{"id": "1112.4508", "abstract": "  We show that the Big Bang singularity of the Friedmann-Lemaitre-Robertson-Walker model does not raise major problems to General Relativity. We prove a theorem showing that the Einstein equation can be written in a non-singular form, which allows the extension of the spacetime before the Big Bang. The physical interpretation of the fields used is discussed. These results follow from our research on singular semi-Riemannian geometry and singular General Relativity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.4508v3.pdf"}
{"id": "1112.4754", "abstract": "  We have studied the decay of a Bose-Einstein condensate of metastable helium atoms in an optical dipole trap. In the regime where two- and three-body losses can be neglected we show that the Bose-Einstein condensate and the thermal cloud show fundamentally different decay characteristics. The total number of atoms decays exponentially with time constant tau; however, the thermal cloud decays exponentially with time constant (4/3)tau and the condensate decays much faster, and non-exponentially. We show that this behaviour, which should be present for all BECs in thermal equilibrium with a considerable thermal fraction, is due to a transfer of atoms from the condensate to the thermal cloud during its decay. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.4754v2.pdf"}
{"id": "1112.5775", "abstract": "  This paper presents a method to describe dynamics of an ion confined in a realistic finite range trap. We model this realistic potential with a solvable one and we obtain dynamical variables (raising and lowering operators) of this potential. We consider coherent interaction of this confined ion in a finite range trap and we show that its center-of-mass motion steady state is a special kind of nonlinear coherent states. Physical properties of this state and their dependence on the finite range of potential are studied. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.5775v1.pdf"}
{"id": "1112.5791", "abstract": "  The logistic map is one of the simplest nonlinear dynamical systems that clearly exhibit the route to chaos. In this paper, we explored the evolution of the logistic map using an open-source microcontroller connected to an array of light emitting diodes (LEDs). We divided the one-dimensional interval [0,1] into ten equal parts, and associated and LED to each segment. Every time an iteration took place a corresponding LED turned on indicating the value returned by the logistic map. By changing some initial conditions of the system, we observed the transition from order to chaos exhibited by the map. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.5791v1.pdf"}
{"id": "1201.1875", "abstract": "  Harmonic analysis is a tool to infer cosmic topology from the measured astrophysical cosmic microwave background CMB radiation. For overall positive curvature, Platonic spherical manifolds are candidates for this analysis. We combine the specific point symmetry of the Platonic manifolds with their deck transformations. This analysis in topology leads from manifolds to orbifolds. We discuss the deck transformations of the orbifolds and give eigenmodes for the harmonic analysis as linear combinations of Wigner polynomials on the 3-sphere. These provide new tools for detecting cosmic topology from the CMB radiation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1201/1201.1875v2.pdf"}
{"id": "1202.0205", "abstract": "  Recent QCD related results from the CDF and the D0 experiments are presented based on proton anti-proton collision data at sqrt(s)=1.96 TeV, taken in Run II of the Fermilab Tevatron Collider. Measured observables include inclusive photon and diphoton production, vector boson plus jets production, event shape variables, and inclusive multijet production. The measurement results are compared to QCD theory calculations in different approximations. A determination of the strong coupling constant from jet data is presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.0205v1.pdf"}
{"id": "1202.0339", "abstract": "  In this work, we explore the possibility of using the Wesenheit function to derive individual distances to Galactic Cepheids, as the dispersion of the reddening free Wesenheit function is smaller than the optical period-luminosity (P-L) relation. When compared to the distances from various methods, the averaged differences between our results and published distances range from -0.061 to 0.009, suggesting that the Wesenheit function can be used to derive individual Cepheid distances. We have also constructed Galactic P-L relations and selected Wesenheit functions based on the derived distances. A by-product from this work is the derivation of Large Magellanic Cloud distance modulus when calibrating the Wesenheit function. It is found to be 18.531 ±0.043 mag. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.0339v1.pdf"}
{"id": "1202.1540", "abstract": "  We study two measures of the complexity of heterogeneous extended systems, taking random Boolean networks as prototypical cases. A measure defined by Shalizi et al. for cellular automata, based on a criterion for optimal statistical prediction [Shalizi et al., Phys. Rev. Lett. 93, 118701 (2004)], does not distinguish between the spatial inhomogeneity of the ordered phase and the dynamical inhomogeneity of the disordered phase. A modification in which complexities of individual nodes are calculated yields vanishing complexity values for networks in the ordered and critical regimes and for highly disordered networks, peaking somewhere in the disordered regime. Individual nodes with high complexity are the ones that pass the most information from the past to the future, a quantity that depends in a nontrivial way on both the Boolean function of a given node and its location within the network. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.1540v3.pdf"}
{"id": "1202.1957", "abstract": "  We present a new algorithm called 'Fast Integrated Spectra Analyzer\" (FISA) that permits fast and reasonably accurate age and reddening determinations for small angular diameter open clusters by using their integrated spectra in the (3600-7400) Å range and currently available template spectrum libraries. This algorithm and its implementation help to achieve astrophysical results in shorter times than from other methods. A brief review is given of the integrated spectroscopic technique applied to the study of open clusters as well as the basic assumptions that justify its use. We describe the numerical algorithm employed in detail, show examples of its application, and provide a link to the code. Our method has successfully been applied to integrated spectroscopy of open clusters, both in the Galaxy and in the Magellanic Clouds, to determine ages and reddenings. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.1957v1.pdf"}
{"id": "1203.0385", "abstract": "  We investigate the dynamics of a strongly interacting spin system that is motivated by current experimental realizations of strongly interacting Rydberg gases in lattices. In particular we are interested in the temporal evolution of quantities such as the density of Rydberg atoms and density-density correlations when the system is initialized in a fully polarized state without Rydberg excitations. We show that in the thermodynamic limit the expectation values of these observables converge at least logarithmically to universal functions and outline a method to obtain these functions. We prove that a finite one-dimensional system follows this universal behavior up to a given time. The length of this universal time period depends on the actual system size. This shows that already the study of small systems allows to make precise predictions about the thermodynamic limit provided that the observation time is sufficiently short. We discuss this for various observables and for systems with different dimensions, interaction ranges and boundary conditions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.0385v1.pdf"}
{"id": "1203.0408", "abstract": "  We explore the minimum energy configurations of repelling particles distributed over n possible locations forming a toric grid. We conjecture that the most energy-efficient way to distribute n/2 particles over this space is to place them in a checkerboard pattern. Numerical experiments validate this conjecture for reasonable choices of the repelling force. In the present paper, we prove this conjecture in a large number of special cases—most notably, when the sizes of the torus are either two or multiples of four in all dimensions and the repelling force is a completely monotonic function of the Lee distance between the particles. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.0408v1.pdf"}
{"id": "1203.0770", "abstract": "  The stochastic resonance (SR) in bistable systems has been extensively discussed with the use of phenomenological Langevin models. By using the microscopic, generalized Caldeira-Leggett (CL) model, we study in this paper, SR of an open bistable system coupled to a bath with a nonlinear system-bath interaction. The adopted CL model yields the non-Markovian Langevin equation with nonlinear dissipation and state-dependent diffusion which preserve the fluctuation-dissipation relation (FDR). From numerical calculations, we find the following: (1) the spectral power amplification (SPA) exhibits SR not only for a and b but also for τ while the stationary probability distribution function is independent of them where a (b) denotes the magnitude of multiplicative (additive) noise and τ expresses the relaxation time of colored noise; (2) the SPA for coexisting additive and multiplicative noises has a single-peak but two-peak structure as functions of a, b and/or τ. These results (1) and (2) are qualitatively different from previous ones obtained by phenomenological Langevin models where the FDR is indefinite or not held. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.0770v6.pdf"}
{"id": "1203.1376", "abstract": "  A two-transmitter Gaussian multiple access wiretap channel with multiple antennas at each of the nodes is investigated. The channel matrices at the legitimate terminals are fixed and revealed to all the terminals, whereas the channel matrix of the eavesdropper is arbitrarily varying and only known to the eavesdropper. The secrecy degrees of freedom (s.d.o.f.) region under a strong secrecy constraint is characterized. A transmission scheme that orthogonalizes the transmit signals of the two users at the intended receiver and uses a single-user wiretap code is shown to be sufficient to achieve the s.d.o.f. region. The converse involves establishing an upper bound on a weighted-sum-rate expression. This is accomplished by using induction, where at each step one combines the secrecy and multiple-access constraints associated with an adversary eavesdropping a carefully selected group of sub-channels. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.1376v1.pdf"}
{"id": "1203.1781", "abstract": "  The measurement of the average depth of the shower maximum is the most commonly used observable for the possible inference of the primary cosmic-ray mass composition. Currently, different experimental Collaborations process and present their data not in the same way, leading to problems in the comparability and interpretation of the results. Whereas <Xmax> is expected to be proportional to <ln A> in ideal conditions, we demonstrate that the finite field-of-view of fluorescence telescopes plus the attenuation in the atmosphere can introduce a non-linearity into this relation, which is specific for each particular detector setup. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.1781v3.pdf"}
{"id": "1203.6839", "abstract": "  A new approach to the parameterization of pion form factors is presented and for illustration applied to the pion vector form factor. It has the correct analytic structure, is at low energies consistent with recent high accuracy analyses of ππ scattering phase shifts and, at high energies, maps smoothly onto the well–known, successful isobar model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.6839v2.pdf"}
{"id": "1204.6580", "abstract": "  The gravitational properties of a torus are investigated. It is shown that a torus can be formed from test particles orbiting in the gravitational field of a central mass. In this case, a toroidal distribution is achieved because of the significant spread of inclinations and eccentricities of the orbits. To investigate the self-gravity of the torus we consider the N-body problem for a torus located in the gravitational field of a central mass. It is shown that in the equilibrium state the cross-section of the torus is oval with a Gaussian density distribution. The dependence of the obscuring efficiency on torus inclination is found. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.6580v2.pdf"}
{"id": "1205.2508", "abstract": "  Power law or generalized polynomial regressions with unknown real-valued exponents and coefficients, and weakly dependent errors, are considered for observations over time, space or space–time. Consistency and asymptotic normality of nonlinear least-squares estimates of the parameters are established. The joint limit distribution is singular, but can be used as a basis for inference on either exponents or coefficients. We discuss issues of implementation, efficiency, potential for improved estimation and possibilities of extension to more general or alternative trending models to allow for irregularly spaced data or heteroscedastic errors; though it focusses on a particular model to fix ideas, the paper can be viewed as offering machinery useful in developing inference for a variety of models in which power law trends are a component. Indeed, the paper also makes a contribution that is potentially relevant to many other statistical models: Our problem is one of many in which consistency of a vector of parameter estimates (which converge at different rates) cannot be established by the usual techniques for coping with implicitly-defined extremum estimates, but requires a more delicate treatment; we present a generic consistency result. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.2508v1.pdf"}
{"id": "1205.3143", "abstract": "  The dynamics of the solar radiative interior are still poorly constrained by comparison to the convective zone. This disparity is even more marked when we attempt to derive meaningful temporal variations. Many data sets contain a small number of modes that are sensitive to the inner layers of the Sun, but we found that the estimates of their uncertainties are often inaccurate. As a result, these data sets allow us to obtain, at best, a low resolution estimate of the solar core rotation rate down to approximately 0.2R. We present inferences based on mode determination resulting from an alternate peak-fitting methodology aimed at increasing the amount of observed modes that are sensitive to the radiative zone, while special care was taken in the determination of their uncertainties. This methodology has been applied to MDI and GONG data, for the whole Solar Cycle 23, and to the newly available HMI data. The numerical inversions of all these data sets result in the best inferences to date of the rotation in the radiative region. These results and the method used to obtain them are discussed. The resulting profiles are shown and analyzed, and the significance of the detected changes discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.3143v2.pdf"}
{"id": "1205.4811", "abstract": "  We propose a method of constructing a network, in which its time structure is directly incorporated, based on a deterministic model from a time series. To construct such a network, we transform a linear model containing terms with different time delays into network topology. The terms in the model are translated into temporal nodes of the network. On each link connecting these nodes, we assign a positive real number representing the strength of relationship, or the \"distance,\" between nodes specified by the parameters of the model. The method is demonstrated by a known system and applied to two actual time series. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.4811v1.pdf"}
{"id": "1205.5767", "abstract": "  Assuming Newton's gravity and GR to be valid at all scales leads to the dark matter hypothesis as a requirement demanded by the observed dynamics and measured baryonic content at galactic and extragalactic scales. Alternatively, modified gravity scenarios where a change of regime appears at acceleration scales a<a_0 have been proposed. This modified regime at a<a_0 will generically be characterised by equilibrium velocities which become independent of distance. Here we identify a critical test in this debate and we propose its application to samples of wide binary stars. Since for 1 M_⊙ systems the acceleration drops below a_0 at scales of around 7000 AU, a statistical survey of wide binaries with relative velocities and separations reaching 10^4 AU and beyond should prove useful to the above debate. We apply the proposed test to the best currently available data. Results show a constant upper limit to the relative velocities in wide binaries which is independent of separation for over three orders of magnitude, in analogy with galactic flat rotation curves in the same a<a_0 acceleration regime. Our results are suggestive of a breakdown of Kepler's third law beyond a ≈ a_0 scales, in accordance with generic predictions of modified gravity theories designed not to require any dark matter at galactic scales and beyond. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.5767v1.pdf"}
{"id": "1206.5968", "abstract": "  A hypothesis on the physical mechanism generating the heartbeat instability in complex (dusty) plasmas is presented. It is suggested that the instability occurs due to the periodically repeated critical transformation on the boundary between the microparticle-free area (void) and the complex plasma. The critical transformation is supposed to be analogous to the formation of the sheath in the vicinity of an electrode. The origin of the transformation is the loss of the electrons and ions on microparticles surrounding the void. We have shown that this hypothesis is consistent with the experimentally measured stability parameter range, with the evolution of the plasma glow intensity and microparticle dynamics during the instability, as well as with the observed excitation of the heartbeat instability by an intensity-modulated laser beam, tuned to the atomic transition of a working gas. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1206/1206.5968v1.pdf"}
{"id": "1206.6675", "abstract": "  We compute the three-loop QCD corrections to the decoupling constant for α_s which relates the Minimal Supersymmetric Standard Model to Quantum Chromodynamics with five or six active flavours. The new results can be used to study the stability of α_s evaluated at a high scale from the knowledge of its value at M_Z. We furthermore derive a low-energy theorem which allows the calculation of the coefficient function of the effective Higgs boson-gluon operator from the decoupling constant. This constitutes the first independent check of the matching coefficient to three loops. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1206/1206.6675v2.pdf"}
{"id": "1207.1029", "abstract": "  In the paper, we consider three quadratic optimization problems which are frequently applied in portfolio theory, i.e, the Markowitz mean-variance problem as well as the problems based on the mean-variance utility function and the quadratic utility.Conditions are derived under which the solutions of these three optimization procedures coincide and are lying on the efficient frontier, the set of mean-variance optimal portfolios. It is shown that the solutions of the Markowitz optimization problem and the quadratic utility problem are not always mean-variance efficient. The conditions for the mean-variance efficiency of the solutions depend on the unknown parameters of the asset returns. We deal with the problem of parameter uncertainty in detail and derive the probabilities that the estimated solutions of the Markowitz problem and the quadratic utility problem are mean-variance efficient. Because these probabilities deviate from one the above mentioned quadratic optimization problems are not stochastically equivalent. The obtained results are illustrated by an empirical study. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1207/1207.1029v2.pdf"}
{"id": "1207.4866", "abstract": "  We present a numerical method to compute an optimal maintenance date for the test case of the heated hold-up tank. The system consists of a tank containing a fluid whose level is controlled by three components: two inlet pumps and one outlet valve. A thermal power source heats up the fluid. The failure rates of the components depends on the temperature, the position of the three components monitors the liquid level in the tank and the liquid level determines the temperature. Therefore, this system can be modeled by a hybrid process where the discrete (components) and continuous (level, temperature) parts interact in a closed loop. We model the system by a piecewise deterministic Markov process, propose and implement a numerical method to compute the optimal maintenance date to repair the components before the total failure of the system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1207/1207.4866v2.pdf"}
{"id": "1207.5454", "abstract": "  The construction of the Agua Negra tunnels that will link Argentina and Chile under the Andes, the world longest mountain range, opens the possibility to build the first deep underground labo- ratory in the Southern Hemisphere. This laboratory has the acronym ANDES (Agua Negra Deep Experiment Site) and its overburden could be as large as ∼1.7 km of rock, or 4500 mwe, providing an excellent low background environment to study physics of rare events like the ones induced by neutrinos and/or dark matter. In this paper we investigate the physics potential of a few kiloton size liquid scintillator detector, which could be constructed in the ANDES laboratory as one of its possible scientific programs. In particular, we evaluate the impact of such a detector for the studies of geoneutrinos and galactic supernova neutrinos assuming a fiducial volume of 3 kilotons as a reference size. We emphasize the complementary roles of such a detector to the ones in the Northern Hemisphere neutrino facilities through some advantages due to its geographical location. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1207/1207.5454v1.pdf"}
{"id": "1207.6548", "abstract": "  We will give an example of a branch group G that has exponential growth but does not contain any non-abelian free subgroups. This answers question 16 from <cit.> positively. The proof demonstrates how to construct a non-trivial word w_a,b(x,y) for any a,b ∈ G such that w_a,b(a,b) = 1. The group G is not just-infinite. We prove that every normal subgroup of G is finitely generated as an abstract group and every proper quotient soluble. Further, G has infinite virtual first Betti number but is not large. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1207/1207.6548v2.pdf"}
{"id": "1208.1258", "abstract": "  We investigate the two-photon transport through a waveguide side-coupling to a whispering-gallery-atom system. Using the Lehmann-Symanzik-Zimmermann (LSZ) reduction approach, we present the general formula for the two-photon processes including the two-photon scattering matrices, the wavefunctions and the second order correlation functions of the out-going photons. Based on the exact results of the second order correlation functions, we analyze the quantum statistics behaviors of the out-going photons for two different cases: (a) the ideal case without the inter-modal coupling in the whispering gallery resonator; (b) the case in the presence of the inter-modal coupling which leads to more complex nonlinear behavior. In the ideal case, we show that the system consists of two independent scattering pathways, a free pathway by a cavity mode without atomic excitation, and a \"Jaynes-Cummings\" pathway described by the Jaynes-Cummings Hamiltonian of a single-mode cavity coupling to an atom. The free pathway does not contribution to correlated two-photon processes. In the presence of intermodal mixing, the system no longer exhibit a free resonant pathway. Instead, both the single-photon and the two photon transport properties depend on the position of the atom. Thus, in the presence of intermodal mixing one can in fact tune the photon correlation properties by changing the position of the atom. Our formalism can be used to treat resonator and cavity dissipation as well. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1208/1208.1258v1.pdf"}
{"id": "1209.2417", "abstract": "  We consider logarithmic extensions of the correlation and response functions of scalar operators for the systems with aging as well as Schrödinger symmetry. Aging is known to be the simplest nonequilibrium phenomena, and its physical significances can be understood by the two-time correlation and response functions. Their logarithmic part is completely fixed by the bulk geometry in terms of the conformal weight of the dual operator and the dual particle number.   Motivated by recent experimental realizations of Kardar-Parisi-Zhang universality class in growth phenomena and its subsequent theoretical extension to aging, we investigate our two-time correlation functions out of equilibrium, which show several qualitatively different behaviors depending on the parameters in our theory. They exhibit either growing or aging, i.e. power-law decaying, behaviors for the entire range of our scaling time. Surprisingly, for some parameter ranges, they exhibit growing at early times as well as aging at later times. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1209/1209.2417v1.pdf"}
{"id": "1209.2465", "abstract": "  We describe experiments on the laser cooling of both helium-rubidium and argon-rubidium gas mixtures by collisional redistribution of radiation. Frequent alkali-noble gas collisions in the ultradense gas, with typically 200 bar of noble buffer gas pressure, shift a highly red detuned optical beam into resonance with a rubidium D-line transition, while spontaneous decay occurs close to the unshifted atomic resonance frequency. The technique allows for the laser cooling of macroscopic ensembles of gas atoms. The use of helium as a buffer gas leads to smaller temperature changes within the gas volume due to the high thermal conductivity of this buffer gas, as compared to the heavier argon noble gas, while the heat transfer within the cell is improved. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1209/1209.2465v1.pdf"}
{"id": "1209.4481", "abstract": "  Synchronization induced by long-range hydrodynamic interactions is attracting attention as a candidate mechanism behind coordinated beating of cilia and flagella. Here we consider a minimal model of hydrodynamic synchronization in the low Reynolds number limit. The model consists of rotors, each of which assumed to be a rigid bead making a fixed trajectory under periodically varying driving force. By a linear analysis, we derive the necessary and sufficient conditions for a pair of rotors to synchronize in phase. We also derive a non-linear evolution equation for their phase difference, which is reduced to minimization of an effective potential. The effective potential is calculated for a variety of trajectory shapes and geometries (either bulk or substrated), for which the stable and metastable states of the system are identified. Finite size of the trajectory induces asymmetry of the potential, which also depends sensitively on the tilt of the trajectory. Our results show that flexibility of cilia or flagella is not a requisite for their synchronized motion, in contrast to previous expectations. We discuss the possibility to directly implement the model and verify our results by optically driven colloids. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1209/1209.4481v2.pdf"}
{"id": "1209.5422", "abstract": "  Linear stability of a current sheet that is subject to an impulsive acceleration due to a shock passage is studied with the effect of guide magnetic field. We find that the current sheet embedded in relativistically magnetized plasma always shows a Richtmyer-Meshkov type instability, while it depends on the density structure in the Newtonian limit. The growth of the instability is expected to generate turbulence around the current sheet that can induce so-called turbulent reconnection whose rate is essentially free from plasma resistivity. Thus, the instability can be applied as a triggering mechanism of rapid magnetic energy release in variety of high-energy astrophysical phenomena such as pulsar wind nebulae, gamma-ray bursts, and active galactic nuclei, where the shock wave is supposed to play a crucial role. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1209/1209.5422v1.pdf"}
{"id": "1209.5434", "abstract": "  Motivated by an application in cell biology, we consider spatial sorting processes defined by particles moving from an initial to a final configuration. We describe an algorithm for constructing a cell complex in space-time, called the medusa, that measures topological properties of the sorting process. The algorithm requires an extension of the kinetic data structures framework from Delaunay triangulations to fixed-radius alpha complexes. We report on several techniques to accelerate the computation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1209/1209.5434v1.pdf"}
{"id": "1209.6443", "abstract": "  The MEG inverse problem refers to the reconstruction of the neural activity of the brain from magnetoencephalography (MEG) measurements. We propose a two-way regularization (TWR) method to solve the MEG inverse problem under the assumptions that only a small number of locations in space are responsible for the measured signals (focality), and each source time course is smooth in time (smoothness). The focality and smoothness of the reconstructed signals are ensured respectively by imposing a sparsity-inducing penalty and a roughness penalty in the data fitting criterion. A two-stage algorithm is developed for fast computation, where a raw estimate of the source time course is obtained in the first stage and then refined in the second stage by the two-way regularization. The proposed method is shown to be effective on both synthetic and real-world examples. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1209/1209.6443v1.pdf"}
{"id": "1210.1058", "abstract": "  We extend the approach in [Ann. Statist. 38 (2010) 2499-2524] for identifying locally optimal designs for nonlinear models. Conceptually the extension is relatively simple, but the consequences in terms of applications are profound. As we will demonstrate, we can obtain results for locally optimal designs under many optimality criteria and for a larger class of models than has been done hitherto. In many cases the results lead to optimal designs with the minimal number of support points. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.1058v1.pdf"}
{"id": "1210.1965", "abstract": "  We show that fluctuations of the fireball shape in the longitudinal direction generate nontrivial rapidity correlations that depend not only on the rapidity difference, y_1 - y_2, but also on the rapidity sum, y_1 + y_2. This is explicitly demonstrated in a simple wounded nucleon model, and the general case is also discussed. We show how to extract different components of the fluctuating fireball shape from the measured two-particle rapidity correlation function. The experimental possibility of studying the longitudinal initial conditions in heavy-ion and proton-proton collisions is emphasized. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.1965v1.pdf"}
{"id": "1210.4259", "abstract": "  We present a study of the observational properties of Millisecond Pulsars (MSPs) by way of their magnetic fields, spin periods and masses. These measurements are derived through the scenario of Accretion Induced Collapse (AIC) of white dwarfs (WDs) in stellar binary systems, in order to provide a greater understanding of the characteristics of MSP populations. In addition, we demonstrate a strong evolutionary connection between neutron stars and WDs with binary companions from a stellar binary evolution perspective via the AIC process. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.4259v3.pdf"}
{"id": "1210.4945", "abstract": "  Using the framework of soft-collinear effective theory with Glauber gluons (), we evaluate medium-induced splitting kernels. Because of the power counting of the effective theory, our results are valid for arbitrary, not necessarily small values of the energy fraction x taken by the emitted parton. In this framework we prove the factorization from the hard process and gauge invariance of the splitting kernels, we also show how nuclear recoil and the phase space cuts can be implemented into the phenomenology. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.4945v1.pdf"}
{"id": "1210.5836", "abstract": "  In this work the magnetization dynamics of clusters supported on non-magnetic substrates is shown to exhibit an unprecedented complex response when subjected to external magnetic fields. The field-driven magnetization reversal of small Co clusters deposited on a Cu(111) surface has been studied by means of first-principles calculations and atomistic spin dynamics simulations. For applied fields ranging from 1 Tesla to 10 Tesla, we observe a coherent magnetization reversal with switching times in the range of several tenths of picoseconds to several nanoseconds, depending on the field strength. We find a non-monotonous dependence of the switching times with respect to the strength of the applied field, which we prove to have its origin in the complex magnetic anisotropy landscape of these low dimensional systems. This effect is shown to be stable for temperatures around 10 K, and is possible to realize over a range of exchange interactions and anisotropy landscapes. Possible experimental routes to achieve this unique switching behaviour are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.5836v1.pdf"}
{"id": "1210.6010", "abstract": "  We propose a method for extracting the shear viscosity over entropy density ratio (eta/s) of the quark-gluon plasma from experimental data. We argue that uncertainty due to poor knowledge of the earliest stages of a heavy-ion collision is smallest for ultra-central events. The most precise value of eta/s can thus be obtained from a global fit to p_T-integrated Fourier harmonics of azimuthal correlations. We further outline a method for quantifying the overall uncertainty in the extracted value. Only after a comprehensive and systematic accounting of all sources of uncertainty can a reliable measurement be claimed. In these proceedings we report preliminary results; full and final results will be presented in a separate publication. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.6010v1.pdf"}
{"id": "1210.6209", "abstract": "  Rough set theory is a useful tool to deal with uncertain, granular and incomplete knowledge in information systems. And it is based on equivalence relations or partitions. Matroid theory is a structure that generalizes linear independence in vector spaces, and has a variety of applications in many fields. In this paper, we propose a new type of matroids, namely, partition-circuit matroids, which are induced by partitions. Firstly, a partition satisfies circuit axioms in matroid theory, then it can induce a matroid which is called a partition-circuit matroid. A partition and an equivalence relation on the same universe are one-to-one corresponding, then some characteristics of partition-circuit matroids are studied through rough sets. Secondly, similar to the upper approximation number which is proposed by Wang and Zhu, we define the lower approximation number. Some characteristics of partition-circuit matroids and the dual matroids of them are investigated through the lower approximation number and the upper approximation number. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.6209v1.pdf"}
{"id": "1210.7265", "abstract": "  The de Broglie - Bohm \"pilot-wave\" theory replaces the paradoxical wave-particle duality of ordinary quantum theory with a more mundane and literal kind of duality: each individual photon or electron comprises a quantum wave (evolving in accordance with the usual quantum mechanical wave equation) and a particle that, under the influence of the wave, traces out a definite trajectory. The definite particle trajectory allows the theory to account for the results of experiments without the usual recourse to additional dynamical axioms about measurements. Instead one need simply assume that particle detectors click when particles arrive at them. This alternative understanding of quantum phenomena is illustrated here for two elementary textbook examples of one-dimensional scattering and tunneling. We introduce a novel approach to reconciling standard textbook calculations (made using unphysical plane-wave states) with the need to treat such phenomena in terms of normalizable wave packets. This allows for a simple but illuminating analysis of the pilot-wave theory's particle trajectories, and an explicit demonstration of the equivalence of the pilot-wave theory predictions with those of ordinary quantum theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.7265v2.pdf"}
{"id": "1210.7584", "abstract": "  The bottomonium states due to their varying binding energies dissolve at different temperatures and thus their nuclear modification factors and relative yields have potential to map the properties of Quark Gluon Plasma (QGP). We estimate the suppression of bottomonia states due to color screening in an expanding QGP of finite lifetime and size with the conditions relevant for PbPb collisions at LHC. The properties of Υ states and recent results on their dissociation temperatures have been used as ingredient in the study. The nuclear modification factors and the ratios of yields of Υ states are then obtained as a function of transverse momentum and centrality. We compare our theoretical calculations with the bottomonia yields measured with CMS in PbPb collisions at √(s_ NN) = 2.76 TeV. The model calculations explain the data very well. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.7584v2.pdf"}
{"id": "1211.1595", "abstract": "  We solve two stochastic control problems in which a player tries to minimize or maximize the exit time from an interval of a Brownian particle, by controlling its drift. The player can change from one drift to another but is subject to a switching cost. In each problem, the value function is written as the solution of a free boundary problem involving second order ordinary differential equations, in which the unknown boundaries are found by applying the principle of smooth fit. For both problems, we compute the value function, we exhibit the optimal strategy and we prove its generic uniqueness. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.1595v2.pdf"}
{"id": "1211.1881", "abstract": "  Dynamic-mode atomic force microscopy (AFM) in liquid remains complicated due to the strong viscous damping of the cantilever resonance. Here we show that a high-quality resonance (Q>20) can be achieved in aqueous solution by attaching a microgram-bead at the end of the nanogram-cantilever. The resulting increase in cantilever mass causes the resonance frequency to drop significantly. However, the force sensitivity — as expressed via the minimum detectable force gradient — is hardly affected, because of the enhanced quality factor. Via the enhancement of the quality factor, the attached bead also reduces the relative importance of noise in the deflection detector. It can thus yield an improved signal-to-noise ratio when this detector noise is significant. We describe and analyze these effects for a set-up which includes magnetic actuation of the cantilevers and which can be easily implemented in any AFM system that is compatible with an inverted optical microscope. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.1881v1.pdf"}
{"id": "1211.5004", "abstract": "  A very promising approach to obtain efficient upconversion of light is the use of triplet-triplet annihilation of excitations in molecular systems. In real materials, besides upconversion, many other physical processes take place - fluorescence, non-radiative decay, annihilation, diffusion - and compete with upconversion. The main objective of this work is to design a proof of principle model that can be used to shed light on the relevance of the interaction between the different physical processes that take part in these kinds of systems. Ultimately, we want to establish general principles that may guide experimentalists toward the design of materials with maximum efficiency. Here we show, in a 1D model system, that even in the presence of these processes upconversion can be optimized by varying the ratio between the two molecular species present in this kind of materials. We derive scaling laws for this ratio and for the maximum efficiency of upconversion, as a function of the diffusion rate J, as well as of the creation and of the decay rate of the excitations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.5004v1.pdf"}
{"id": "1212.0754", "abstract": "  Continuing work initiated in an earlier publication [Ichita, Yamada and Asada, Phys. Rev. D 83, 084026 (2011)], we reexamine the post-Newtonian effects on Lagrange's equilateral triangular solution for the three-body problem. For three finite masses, it is found that a triangular configuration satisfies the post-Newtonian equation of motion in general relativity, if and only if it has the relativistic corrections to each side length. This post-Newtonian configuration for three finite masses is not always equilateral and it recovers previous results for the restricted three-body problem when one mass goes to zero. For the same masses and angular velocity, the post-Newtonian triangular configuration is always smaller than the Newtonian one. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1212/1212.0754v1.pdf"}
{"id": "1212.2534", "abstract": "  Many natural, technological, and social systems incorporate multiway interactions, yet are characterized and measured on the basis of weighted pairwise interactions. In this article, I propose a family of models in which pairwise interactions originate from multiway interactions, by starting from ensembles of hypergraphs and applying projections that generate ensembles of weighted projected networks. I calculate analytically the statistical properties of weighted projected networks, and suggest ways these could be used beyond theoretical studies. Weighted projected networks typically exhibit weight disorder along links even for very simple generating hypergraph ensembles. Also, as the size of a hypergraph changes, a signature of multiway interaction emerges on the link weights of weighted projected networks that distinguishes them from fundamentally weighted pairwise networks. This signature could be used to search for hidden multiway interactions in weighted network data. I find the percolation threshold and size of the largest component for hypergraphs of arbitrary uniform rank, translate the results into projected networks, and show that the transition is second order. This general approach to network formation has the potential to shed new light on our understanding of weighted networks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1212/1212.2534v2.pdf"}
{"id": "1212.3990", "abstract": "  Observation of gamma-rays from dwarf galaxies is an effective way to search for particle dark matter. Using 4-year data of Fermi-LAT observations on a series of Milky Way satellites, we develop a general way to search for the signals from dark matter annihilation in such objects. Instead of giving prior information about the energy spectrum of dark matter annihilation, we bin the Fermi-LAT data into several energy bins and build a likelihood map in the \"energy bin - flux\" plane. The final likelihood of any spectrum can be easily derived through combining the likelihood of all the energy bins. It gives consistent result with that directly calculated using the Fermi Scientific Tool. This method is very efficient for the study of any specific dark matter models with gamma-rays. We use the new likelihood map with Fermi-LAT 4 year data to fit the parameter space in three representative dark matter models: i) toy dark matter model, ii) effective dark matter operators, and iii) supersymmetric neutralino dark matter. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1212/1212.3990v2.pdf"}
{"id": "1212.4290", "abstract": "  We study the thermal escape problem in the moderate-to-high and high damping regime of a system with a parabolic barrier. We present a formula that matches our numerical results accounting for finite barrier effects, and compare it with previous works. We also show results for the full damping range. We quantitatively study some aspects on the relation between mean first passage time and the definition of a escape rate. To finish we apply our results and considerations in the framework of force spectroscopy problems. We study the differences on the predictions using the different theories and discuss the role of γḞ as the relevant parameter at high damping. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1212/1212.4290v2.pdf"}
{"id": "1212.4402", "abstract": "  Horava-Lifshitz gravity with \"detailed balance\" but without the projectability assumption is discussed. It is shown that detailed balance is quite efficient in limiting the proliferation of couplings in Horava-Lifshitz gravity, and that its implementation without the projectability assumption leads to a theory with sensible dynamics. However, the (bare) cosmological constant is restricted to be large and negative. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1212/1212.4402v1.pdf"}
{"id": "1212.5362", "abstract": "  Constraint Molecular dynamics CoMD calculations have been performed for asymmetric nuclear matter (NM) by using a simple effective interactions of the Skyrme type. The set of parameter values reproducing common accepted saturation properties of nuclear matter have been obtained for different degree of stiffness characterizing the iso-vectorial potential density dependence. A comparison with results obtained in the limit of the Semi-Classical Mean Field approximation using the same kind of interaction put in evidence the role played by the many-body correlations in to explain the noticeable differences obtained in the parameter values in the two cases. Even if from a numerical point of view the obtained results are strictly valid for the CoMD model, some rather general feature of the discussed correlations can give a wider meaning to the obtained differences being strongly related to the spacial correlations generated in the semiclassical wave packets dynamics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1212/1212.5362v1.pdf"}
{"id": "1212.6880", "abstract": "  The NA61/SHINE experiment aims to discover the critical point of strongly interacting matter and study properties of the onset of deconfinement. It also performs precise hadron production measurements for the neutrino and cosmic rays experiments. These goals are being achieved by measurements of hadron production properties in nucleus-nucleus, proton-proton and proton/pion-nucleus interactions as a function of collision energy and size of the colliding nuclei. This contribution presents preliminary results from the NA61 ion program on single-particle spectra and identified particle multiplicity fluctuations in p+p interactions at the CERN SPS. Comparisons with results from p+p and Pb+Pb collisions obtained by the NA49 experiment are shown. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1212/1212.6880v2.pdf"}
{"id": "1301.3697", "abstract": "  The synergy between the Fermi-LAT and ground-based Cherenkov telescope arrays gives us the opportunity for the first time to characterize the high-energy emission from blazars over 5 decades in energy, from 100 MeV to 10 TeV. In this study, we perform a Fermi-LAT spectral analysis for TeV-detected blazars and combine it with archival TeV data. We examine the observational properties in the gamma-ray band of our sample of TeV-detected blazars and compare the results with X-ray and GeV-selected populations. The spectral energy distributions (SEDs) that result from combining Fermi-LAT and ground-based spectra are studied in detail. Simple parameterizations such as a power-law function do not always reproduce the high-energy SEDs, where spectral features that could indicate intrinsic absorption are observed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.3697v2.pdf"}
{"id": "1301.4961", "abstract": "  We propose a method for testing cosmic homogeneity based on the Shannon entropy in Information theory and test the potentials and limitations of the method on Monte Carlo simulations of some homogeneous and inhomogeneous 3D point process in a finite region of space. We analyze a set of N-body simulations to investigate the prospect of determining the scale of homogeneity with the proposed method and show that the method could serve as an efficient tool for the study of homogeneity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.4961v1.pdf"}
{"id": "1301.6107", "abstract": "  Entanglement of a quantum system depends upon relative phase in complicated ways, which no single measurement can reflect. Because of this, entanglement witnesses are necessarily limited in applicability and/or utility. We propose here a solution to the problem using quantum neural networks. A quantum system contains the information of its entanglement; thus, if we are clever, we can extract that information efficiently. As proof of concept, we show how this can be done for the case of pure states of a two-qubit system, using an entanglement indicator corrected for the anomalous phase oscillation. Both the entanglement indicator and the phase correction are calculated by the quantum system itself acting as a neural network. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.6107v1.pdf"}
{"id": "1302.0027", "abstract": "  We investigate the effect of strain-induced gauge fields on statistical distribution of energy levels of triangular graphene nanoflakes with zigzag edges. In the absence of strain fields but in the presence of weak potential disorder such systems were found in Ref. [1] to display the spectral statistics of the Gaussian unitary ensemble (GUE) due to the effective time-reversal (symplectic) symmetry breaking. Here show that, in the absence of disorder, strain fields may solely lead to spectral fluctuations of GUE providing a nanoflake is deformed such that all its geometric symmetries are broken. In a particular case when a single mirror symmetry is preserved the spectral statistics follow the Gaussian orthogonal ensemble (GOE) rather then GUE. The corresponding transitions to quantum chaos are rationalized by means of additive random-matrix models and the analogy between strain-induced gauge fields and real magnetic fields is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1302/1302.0027v2.pdf"}
{"id": "1302.0514", "abstract": "  Lens magnification by galaxy clusters induces characteristic spatial variations in the number counts of background sources, amplifying their observed fluxes and expanding the area of sky, the net effect of which, known as magnification bias, depends on the intrinsic faint-end slope of the source luminosity function. The bias is strongly negative for red galaxies, dominated by the geometric area distortion, whereas it is mildly positive for blue galaxies, enhancing the blue counts toward the cluster center. We generalize the Bayesian approach of Umetsu et al. for reconstructing projected cluster mass profiles, by incorporating multiple populations of background sources for magnification bias measurements and combining them with complementary lens distortion measurements, effectively breaking the mass-sheet degeneracy and improving the statistical precision of cluster mass measurements. The approach can be further extended to include strong-lensing projected mass estimates, thus allowing for non-parametric absolute mass determinations in both the weak and strong regimes. We apply this method to our recent CLASH lensing measurements of MACS J1206.2-0847, and demonstrate how combining multi-probe lensing constraints can improve the reconstruction of cluster mass profiles. This method will also be useful for a stacked lensing analysis, combining all lensing-related effects in the cluster regime, for a definitive determination of the averaged mass profile. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1302/1302.0514v4.pdf"}
{"id": "1303.0685", "abstract": "  In this work we examine the effect of phase-space noncommutativity on some typically quantum properties such as quantum beating, quantum information, and decoherence. To exemplify these issues we consider the two-dimensional noncommutative quantum harmonic oscillator whose components behavior we monitor in time. This procedure allows us to determine how the noncommutative parameters are related to the missing information quantified by the linear quantum entropy and by the mutual information between the relevant Hilbert space coordinates. Particular questions concerning the thermodynamic limit of some relevant properties are also discussed in order to evidence the effects of noncommutativity. Finally, through an analogy with the Zeeman effect, we identify how some aspects of the axial symmetry of the problem suggest the possibility of decoupling the noncommutative quantum perturbations from unperturbed commutative well-known solutions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1303/1303.0685v2.pdf"}
{"id": "1303.1858", "abstract": "  Families of generalized spatially-coupled low-density parity-check (GSC-LDPC) code ensembles can be formed by terminating protograph-based generalized LDPC convolutional (GLDPCC) codes. It has previously been shown that ensembles of GSC-LDPC codes constructed from a protograph have better iterative decoding thresholds than their block code counterparts, and that, for large termination lengths, their thresholds coincide with the maximum a-posteriori (MAP) decoding threshold of the underlying generalized LDPC block code ensemble. Here we show that, in addition to their excellent iterative decoding thresholds, ensembles of GSC-LDPC codes are asymptotically good and have large minimum distance growth rates. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1303/1303.1858v1.pdf"}
{"id": "1303.1876", "abstract": "  We present an ultraviolet spectrum and light curve of the short orbital period cataclysmic variable EZ Lyn obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope 14 months after its dwarf nova outburst, along with ground-based optical photometry. The UV spectrum can be fit with a 13,100K, log g=8 white dwarf using 0.5 solar composition, while fits to the individual lines are consistent with solar abundance for Si and Al, but only 0.3 solar for C. The Discrete Fourier Transforms of the UV and optical light curves at 14 months following outburst show a prominent period at 256 sec. This is the same period reported by Pavlenko in optical data obtained 7 months and one year after outburst, indicating its long term stability over several months, but this period is not evident in the pre-outburst data and is much shorter than the 12.6 min period that was seen in observations obtained during an interval from 8 months to 2.5 years after the 2006 outburst. In some respects, the long and short periods are similar to the behavior seen in GW Lib after its outburst but the detailed explanation for the appearance and disappearance of these periods and their relation to non-radial pulsation modes remain to be explored with theoretical models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1303/1303.1876v1.pdf"}
{"id": "1303.7249", "abstract": "  Starting from a microscopic theory for atomic scatterers, we describe the scattering of light by a single atom and study the coherent propagation of light in a cold atomic cloud in the presence of a magnetic field B in the mesoscopic regime. Non-pertubative expressions in B are given for the magneto-optical effects and optical anisotropy. We then consider the multiple scattering regime and address the fate of the coherent backscattering (CBS) effect. We show that, for atoms with nonzero spin in their ground state, the CBS interference contrast can be increased compared to its value when B=0, a result at variance with classical samples. We validate our theoretical results by a quantitative comparison with experimental data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1303/1303.7249v1.pdf"}
{"id": "1304.2018", "abstract": "  In this paper, I examine what I refer to as the spike doctrine, which is the generally held belief in neuroscience that information in the brain is encoded by sequences of neural action potentials. I present the argument that specific neurochemicals, and not spikes, are the elementary units of information in the brain. I outline several predictions that arise from this interpretation, relate them to results in the current research literature, and show how they address some open questions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.2018v2.pdf"}
{"id": "1304.5111", "abstract": "  We have combined neutron reflectometry with rheology in order to investigate the solid boundary of liquids and polymers under shear deformation. Our approach allows one to apply a controlled stress to a material while resolving the structural arrangements on the sub nanometer length scale with neutron reflectivity, off-specular and small angle scattering at the same time. The specularly reflected neutron intensity of a 20 ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.5111v2.pdf"}
{"id": "1305.0387", "abstract": "  The shapes of invariant differential cross section for charged particle production as function of transverse momentum measured in heavy-ion collisions are analyzed. The data measured at RHIC and LHC are treated as function of energy density according to a recent theoretical approach. The Boltzmann-like statistical distribution is extracted from the whole statistical ensemble of produced hadrons using the introduced model. Variation of the temperature, characterizing this exponential distribution, is studied as function of energy density. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.0387v1.pdf"}
{"id": "1305.1857", "abstract": "  We present the results of an infrared photometric survey performed with NICS@TNG in the nearby starburst galaxy NGC 4214. We derived accurate integrated JK magnitudes of 10 young massive clusters and compared them with the already available Hubble Space Telescope ultraviolet colors. These clusters are located in the combined ultraviolet-infrared colors planes on well defined sequences, whose shapes allow a precise determination of their age. By means of the comparison with suitable stellar evolution models we estimated ages, metallicities, reddening and masses of these clusters. All the analyzed clusters appear to be younger than log(t/yr)<8.4, moderately metal-rich and slightly less massive than present-day Galactic globular clusters. The derived ages for clusters belonging to the secondary HII star forming complex are significantly larger than those previously estimated in the literature. We also discuss the possibility of using the ultraviolet-infrared color-color diagram to select candidate young massive clusters hosting multiple stellar populations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.1857v1.pdf"}
{"id": "1305.3346", "abstract": "  We observed elastic collisions between laser-cooled fermionic lithium atoms and calcium ions at the energy range from 100 mK to 3 K. Lithium atoms in an optical-dipole trap were transported to the center of the ion trap using an optical tweezer technique, and a spatial overlap of the atoms and ions was realized in order to observe the atom-ion interactions. The elastic scattering rate was determined from the decay of atoms due to elastic collisions with ions. The collision-energy dependence of the elastic scattering cross-section was consistent with semi-classical collision theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.3346v1.pdf"}
{"id": "1305.3956", "abstract": "  We investigated a multilayer graphene-dielectric composite material, comprising graphene sheets separated by subwavelength-thick dielectric spacer, and found it to exhibit hyperbolic isofrequency wavevector dispersion at far- and mid-infrared frequencies allowing propagation of waves that would be otherwise evanescent in a dielectric. Electrostatic biasing was considered for tunable and controllable transition from hyperbolic to elliptic dispersion. We explored the validity and limitation of the effective medium approximation (EMA) for modeling wave propagation and cutoff of the propagating spatial spectrum due to the Brillouin zone edge. We found that EMA is capable of predicting the transition of the isofrequency dispersion diagram under certain conditions. The graphene-based composite material allows propagation of backward waves under the hyperbolic dispersion regime and of forward waves under the elliptic regime. Transition from hyperbolic to elliptic dispersion regimes is governed by the transverse epsilon-near-zero (TENZ) condition, which implies a flatter and wider propagating spectrum with higher attenuation, when compared to the hyperbolic regime. We also investigate the tunable transparency of the multilayer at that condition in contrast to other materials exhibiting ENZ phenomena. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.3956v1.pdf"}
{"id": "1305.4627", "abstract": "  In this paper, we propose an explicit scheme to fully recover a multiple-qubit state subject to a phase damping noise. We establish the theoretical framework and the operational procedure to restore an unknown initial quantum state for an N-qubit model interacting with either individual baths or a common bath. We give an explicit construction of the random unitary (RU) Kraus decomposition for an N-qubit model interacting with a common bath. We also demonstrate how to use only one unitary reversal operation to restore an arbitrary state with phase damping noise. In principle, the initial state can always be recovered with a success probability of 1. Interestingly, we found that non-RU decomposition can also be used to restore some particular entangled states. This may open a new path to restore a quantum state beyond the standard RU scheme. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.4627v2.pdf"}
{"id": "1306.3180", "abstract": "  We generated an event catalog with an automated detection algorithm based on the entire EUVI image database observed with the two Solar Terrestrial Relations Observatory STEREO-A and -B spacecraft over the first six years of the mission (2006 – 2012). The event catalog includes the heliographic positions of some 20 000 EUV events, transformed from spacecraft coordinates to Earth coordinates, and information on associated GOES flare events (down to the level of GOES A5-class flares). The 304  wavelength turns out to be the most efficient channel for flare detection (79 ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.3180v1.pdf"}
{"id": "1306.3740", "abstract": "  We present a two-fluid description for iron-based superconductors, which contains an itinerant electron Fermi-liquid and a local moment spin-liquid, coupled together via an effective Hund's rule interaction. We examine the low-energy collective behavior of such a system. We find that an electron-spinon composite mode emerges in the intermediate coupling regime, which may account for the hump-dip behavior observed in the resent scanning tunneling spectroscopy experiments. The superconductivity and spin-density-wave phases are consistently described within the same framework. Possible experimental test is also proposed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.3740v3.pdf"}
{"id": "1306.4795", "abstract": "  We investigate the localization of stiff directed lines with bending energy by a short-range random potential. We apply perturbative arguments, Flory scaling arguments, a variational replica calculation, and functional renormalization to show that a stiff directed line in 1+d dimensions undergoes a localization transition with increasing disorder for d > 2=3. We demonstrate that this transition is accessible by numerical transfer matrix calculations in 1+1 dimensions and analyze the properties of the disorder dominated phase in detail. On the basis of the two-replica problem, we propose a relation between the localization of stiff directed lines in 1+d dimensions and of directed lines under tension in 1+3d dimensions, which is strongly supported by identical free energy distributions. This shows that pair interactions in the replicated Hamiltonian determine the nature of directed line localization transitions with consequences for the critical behavior of the Kardar-Parisi-Zhang (KPZ) equation. We support the proposed relation to directed lines via multifractal analysis revealing an analogous Anderson transition-like scenario and a matching correlation length exponent. Furthermore, we quantify how the persistence length of the stiff directed line is reduced by disorder. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.4795v1.pdf"}
{"id": "1306.5137", "abstract": "  In this paper we have studied the onset of holographic s-wave condensate in the (4+1) dimensional planar Gauss-Bonnet-AdS black hole background with several non-linear corrections to the gauge field. In the probe limit, performing explicit analytic computations, with and without magnetic field, we found that these higher order corrections indeed affect various quantities characterising the holographic superconductors. Also, performing a comparative study of the two non-linear electrodynamics it has been shown that the exponential electrodynamics has stronger effects on the formation of the scalar hair. We observe that our results agree well with those obtained numerically [Z. Zhao et. al., Nucl. Phys. B 871 [FS] (2013) 98]. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.5137v3.pdf"}
{"id": "1306.5943", "abstract": "  We report on new measurements of the beam asymmetry for ω photo-production on proton and neutron in Hydrogen and Deuterium targets from the GRAAL collaboration. The beam asymmetry values are extracted from the reaction threshold (E_γ = 1.1 GeV in the free nucleon kinematics) up to 1.5 GeV of incoming photon energy. For the first time both the radiative and the three-pion decay channels are simultaneously investigated on the free proton. Results from the two decay channels are in agreement and provide important constraints for the determination of resonant state contributions to the ω production mechanism. First experimental results on the deuteron allow the extraction of the Σ beam asymmetry on quasi-free nucleons. Comparison of the results for free and quasi-free kinematics on the proton shows a generally reasonable agreement, similar to the findings in pseudo-scalar meson photo-production reactions. For the first time measurements on quasi-free neutrons are available, showing that both the strength and the angular distributions of the beam asymmetry are sensibly different from the results on the proton target. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.5943v1.pdf"}
{"id": "1307.0868", "abstract": "  Many disordered lattices exhibit remarkable universality in their low temperature properties, similar to that found in amorphous solids. Recently a two-TLS (two-level system) model was derived based on the microscopic characteristics of disordered lattices. Within the two-TLS model the quantitative universality of phonon attenuation, and the energy scale of 1-3 K below which universality is observed, are derived as a consequence of the existence of two types of TLSs, differing by their interaction with the phonon field. In this paper we calculate analytically and numerically the densities of states (DOS) of the weakly and strongly interacting TLSs. We find that the DOS of the former can be well described by a Gaussian, whereas the DOS of the latter have a power law correlation gap at low energies, with an intriguing dependence of the power on the short distance cutoff of the interaction. Both behaviors are markedly different from the logarithmic gap exhibited by a single species of interacting TLSs. Our analytical results are verified against extensive Monte Carlo simulations. Our results support the notion that it is the weakly interacting τ-TLSs that dictate the standard low temperature glassy physics. Yet, the power-law DOS we find for the S-TLSs enables the prediction of a number of deviations from the universal glassy behavior that can be tested experimentally. Possible relevance of our results to recent experimental findings in hydrogenated amorphous films, and more generally to amorphous systems, is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.0868v3.pdf"}
{"id": "1307.1104", "abstract": "  Quantum tunneling is the quantum-mechanical effect where a particle tunnels through a classically forbidden region. Double Square Well Potential (DSWP) is a system where this phenomenon is feasible. Numerous phenomena can be illustrated by considering motion in a pair of wells that are separated by a barrier of finite height and width. The energy level splitting, resulting from barrier penetration, is the reason of the so-called inversion spectrum, which is an example of quantum tunneling. Out of several molecules (NH_3, PH_3, AsH_3, NH_2CN) where this inversion phenomenon occurs, ammonia molecule NH_3 provides a nice physical realization of a vibrational system with a DSWP. The main goal of the present work is to examine the implications of quantum tunneling on information entropy measures (Shannon's and Fisher's) and statistical complexity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.1104v1.pdf"}
{"id": "1307.3350", "abstract": "  Circumstellar dust particles can be captured in a mean motion resonance with a planet and simultaneously be affected by non-gravitational effects. It is possible to describe the secular variations of a particle orbit in the mean motion resonance analytically using averaged resonant equations. We derive the averaged resonant equations from the equations of motion in near-canonical form. The secular variations of the particle orbit depending on the orientation of the orbit in space are taken into account. The averaged resonant equations can be derived/confirmed also from Lagrange's planetary equations. We apply the derived theory to the case when the non-gravitational effects are the Poynting–Robertson effect, the radial stellar wind, and an interstellar wind. The analytical and numerical results obtained are in excellent agreement. We found that the types of orbits correspond to libration centers of the conservative problem. The averaged resonant equations can lead to a system of equations which hold for stationary points in a subset of resonant variables. Using this system we show analytically that for the considered non-gravitational effects, all stationary points should correspond to orbits which are stationary in interplanetary space after an averaging over a synodic period. In an exact resonance, the stationary orbits are stable. The stability is achieved by a periodic repetition of the evolution during the synodic period. Numerical solutions of this system show that there are no stationary orbits for either the exact or non-exact resonances. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.3350v5.pdf"}
{"id": "1307.5518", "abstract": "  We address the geometrical structure of the \"skewed\" correlator of two space-like separated (almost) oppositely directed Wilson lines. Similar objects occur in the analysis of the transverse-momentum broadening probability function, the first moment of which is associated with the jet quenching parameter. We start from the Euclidean space formulation and then transform the result to the Minkowski light-cone geometry, arguing that this procedure is consistent in the leading order of the perturbative expansion. We discuss as well the issues of the UV, rapidity and IR singularities, and possible use of the proposed approach in lattice simulations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.5518v3.pdf"}
{"id": "1307.7009", "abstract": "  In dense underwater sensor networks (UWSN), the major confronts are high error probability, incessant variation in topology of sensor nodes, and much energy consumption for data transmission. However, there are some remarkable applications of UWSN such as management of seabed and oil reservoirs, exploration of deep sea situation and prevention of aqueous disasters. In order to accomplish these applications, ignorance of the limitations of acoustic communications such as high delay and low bandwidth is not feasible. In this paper, we propose Adaptive mobility of Courier nodes in Threshold-optimized Depth-based routing (AMCTD), exploring the proficient amendments in depth threshold and implementing the optimal weight function to achieve longer network lifetime. We segregate our scheme in 3 major phases of weight updating, depth threshold variation and adaptive mobility of courier nodes. During data forwarding, we provide the framework for alterations in threshold to cope with the sparse condition of network. We ultimately perform detailed simulations to scrutinize the performance of our proposed scheme and its comparison with other two notable routing protocols in term of network lifetime and other essential parameters. The simulations results verify that our scheme performs better than the other techniques and near to optimal in the field of UWSN. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.7009v1.pdf"}
{"id": "1307.7342", "abstract": "  The presented study explores the extent to which tactile stimuli delivered to five chest positions of a healthy user can serve as a platform for a brain computer interface (BCI) that could be used in an interactive application such as robotic vehicle operation. The five chest locations are used to evoke tactile brain potential responses, thus defining a tactile brain computer interface (tBCI). Experimental results with five subjects performing online tBCI provide a validation of the chest location tBCI paradigm, while the feasibility of the concept is illuminated through information-transfer rates. Additionally an offline classification improvement with a linear SVM classifier is presented through the case study. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.7342v1.pdf"}
{"id": "1308.0262", "abstract": "  Self healing mechanisms of vacancy defects in graphene and silicene are studied using first principles calculations. We investigated host adatom adsorption, diffusion, vacancy formation and revealed atomistic mechanisms in the healing of single, double and triple vacancies of single layer graphene and silicene. Silicon adatom, which is adsorbed to silicene at the top site forms a dumbbell like structure by pushing one Si atom underneath. The asymmetric reconstruction of the single vacancy in graphene is induced by the magnetization through the rebonding of two dangling bonds and acquiring a significant magnetic moment through remaining unsaturated dangling bond. In silicene, three two-fold coordinated atoms surrounding the single vacancy become four-fold coordinated and nonmagnetic through rebonding. The energy gained through new bond formation becomes the driving force for the reconstruction. Under the external supply of host atoms, while the vacancy defects of graphene heal perfectly, Stone-Wales defect can form in the course of healing of silicene vacancy. The electronic and magnetic properties of suspended, single layer graphene and silicene are modified by reconstructed vacancy defects. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.0262v1.pdf"}
{"id": "1308.3993", "abstract": "  We present a theoretical study of the effects of the next-nearest-neighbor (NNN) hopping (t_2) on the properties of non-interacting bosons in optical lattices in the presence of an Aubry-André quasi-disorder. First we investigate, employing exact diagonalization, the effects of t_2 on the localization properties of a single boson. The localization is monitored using an entanglement measure as well as with inverse participation ratio. We find that the sign of t_2 has a significant influence on the localization effects. We also provide analytical results in support of the trends found in the localization behavior. Further, we extend these results including the effects of a harmonic potential which obtains in experiments. Next, we study the effects of t_2 on Bose-Einstein condensation. We find that, a positive t_2 strongly enhances the low temperature thermal depletion of the condensate while a negative t_2 reduces it. It is also found that, for a fixed temperature, increasing the quasi-disorder strength reduces the condensate fraction in the extended regime while enhancing it in the localized regime. We also investigate the effects of boundary conditions and that of the phase of the AA potential on the condensate. These are found to have significant effects on the condensate fraction in the localization transition region. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.3993v3.pdf"}
{"id": "1309.1143", "abstract": "  We study the formation of Majorana fermions in honeycomb-lattice structures in the presence of a Zeeman field, Rashba spin-orbit coupling, and in the proximity of an s-wave superconductor. We show that an exact mapping exists between an anisotropic hexagonal-lattice nanoribbon at k = 0 and a one-dimensional chain, for which the existence of Majorana fermions has been extensively discussed. Consequently we can predict the conditions for the emergence of Majorana fermions at the edges of such ribbon, and relate the existence of Majoranas to a band inversion in the bulk band structure. Moreover we find that similar situations arise in isotropic lattices and we give some examples which show the formation of Majorana fermions in these structures. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.1143v4.pdf"}
{"id": "1309.2159", "abstract": "  We report rotation periods, variability characteristics, gyrochronological ages for  950 of the Kepler Object of Interest host stars. We find a wide dispersion in the amplitude of the photometric variability as a function of rotation, likely indicating differences in the spot distribution among stars. We use these rotation periods in combination with published spectroscopic measurements of vsini and stellar parameters to derive the stellar inclination in the line-of-sight, and find a number of systems with possible spin-orbit misalignment. We additionally find several systems with close-in planet candidates whose stellar rotation periods are equal to or twice the planetary orbital period, indicative of possible tidal interactions between these planets and their parent stars. If these systems survive validation to become confirmed planets, they will provide important clues to the evolutionary history of these systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.2159v1.pdf"}
{"id": "1309.2505", "abstract": "  We present reconstruction algorithms for smooth signals with block sparsity from their compressed measurements. We tackle the issue of varying group size via group-sparse least absolute shrinkage selection operator (LASSO) as well as via latent group LASSO regularizations. We achieve smoothness in the signal via fusion. We develop low-complexity solvers for our proposed formulations through the alternating direction method of multipliers. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.2505v1.pdf"}
{"id": "1309.5619", "abstract": "  The efficiency and cooling power of a two-terminal thermoelectric refrigerator are analyzed near the limit of vanishing dissipation (ideal system), where the optimal efficiency is the Carnot one, but the cooling power then unfortunately vanishes. This limit, where transport occurs only via a single sharp electronic energy, has been referred to as \"strong coupling\" or \"the best thermoelectric\". It follows however, that \"parasitic\" effects that make the system deviate from the ideal limit, and reduce the efficiency from the Carnot limit, are crucial for the usefulness of the device. Among these parasitics, there are: parallel phonon conduction, finite width of the electrons' transport band and more than a single energy transport channel. In terms of a small parameter characterizing the deviation from the ideal limit, the efficiency and power grow linearly, and the dissipation quadratically. The results are generalized to the case of broken time-reversal symmetry, and the major nontrivial changes are discussed. Finally, the recent universal relation between the thermopower and the asymmetry of the dissipation between the two terminals is briefly discussed, including the small dissipation limit. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.5619v1.pdf"}
{"id": "1309.7205", "abstract": "  We report ab initio predictions on the proper multiferroic (ferromagnetic, insulating and ferroelectric) character of PbTiO_3 doped with vanadium. V impurities coupled ferromagnetically carry a magnetization of 1 μ_ B each. The coupling is expected to be strong, since the paramagnetic solution is higher by 150 meV/vanadium, and no stable antiferromagnetic solution was found. The electronic gap in the doped system is about 0.2-0.3 eV in GGA, hence the system is properly multiferroic. V doping increases the spontaneous polarization in PbTiO_3, with an approximate percentual rate of 0.7 μC/cm^2. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.7205v1.pdf"}
{"id": "1309.7373", "abstract": "  To detect or exclude the existence of hidden sector photons or axion like particles, a table-top \"microwaves shining through the wall\" experiment has been set up at CERN. An overview of the experimental layout is given, the technical challenges involved are reviewed and the measurement procedure including data-evaluation and its results to date are shown. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.7373v1.pdf"}
{"id": "1310.0942", "abstract": "  We study the spectra of the molecular orbital Hessian (stability matrix) and random-phase approximation Hamiltonian of broken-symmetry Hartree-Fock solutions, focusing on zero eigenvalue modes. After all negative eigenvalues are removed from the Hessian by following their eigenvectors downhill, one is left with only positive and zero eigenvalues. Zero modes correspond to orbital rotations with no restoring force. These rotations determine states in the Goldstone manifold, which originates from a spontaneously broken continuous symmetry in the wave function. Zero modes can be classified as improper or proper according to their different mathematical and physical properties. Improper modes arise from symmetry breaking and their restoration always lowers the energy. Proper modes, on the other hand, correspond to degeneracies of the wave function, and their symmetry restoration does not necessarily lower the energy. We discuss how the RPA Hamiltonian distinguishes between proper and improper modes by doubling the number of zero eigenvalues associated with the latter. Proper modes in the Hessian always appear in pairs which do not double in RPA. We present several pedagogical cases exemplifying the above statements. The relevance of these results for projected Hartree-Fock methods is also addressed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.0942v1.pdf"}
{"id": "1310.1807", "abstract": "  We present firstly a four-dimensional spherical symmetric black hole with small Weyl corrections and find that with increasing Weyl corrections the region of the event horizon existence for the black hole in the parameter space increases for the negative Weyl coupling parameter and decreases for the positive one. Moreover, we also obtain a rotating charged black hole with weak Weyl corrections by the method of complex coordinate transformation. Our results show that the sign of Weyl coupling parameter α yields the different spatial topology of the event horizons for the black hole with its parameters lied in some special regions in the parameter space. We also analyze the dependence of the ergosphere on the Weyl coupling parameter α and find that with the increase of the Weyl corrections the ergosphere in the equatorial plane becomes thick for a black hole with α>0, but becomes thin in the case with α<0, which means that the energy extraction become easier in the background of a black hole with the positive Weyl coupling parameter, but more difficult in the background of a black hole with the negative one. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.1807v2.pdf"}
{"id": "1310.7247", "abstract": "  In this paper we investigate the problem of designing a spectrum scanning strategy to detect an intelligent Invader who wants to utilize spectrum undetected for his/her unapproved purposes. To deal with this problem we apply game-theoretical tools. We model the situation as a game between a Scanner and an Invader where the Invader faces a dilemma: the more bandwidth the Invader attempts to use leads to a larger payoff if he is not detected, but at the same time also increases the probability of being detected and thus fined. Similarly, the Scanner faces a dilemma: the wider the bandwidth scanned, the higher the probability of detecting the Invader, but at the expense of increasing the cost of building the scanning system. The equilibrium strategies are found explicitly and reveal interesting properties. In particular, we have found a discontinuous dependence of the equilibrium strategies on the network parameters, fine and the type of the Invader's award. This discontinuity on fine means that the network provider has to take into account a human factor since some threshold values of fine could be very sensible for the Invader, while in other situations simply increasing the fine has minimal deterrence impact. Also we show how different reward types for the Invader (e.g. motivated by using different type of application, say, video-streaming or downloading files) can be incorporated into scanning strategy to increase its efficiency. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.7247v1.pdf"}
{"id": "1310.8081", "abstract": "  We investigate the creation of entanglement between two quantum emitters interacting with a realistic common stationary electromagnetic field out of thermal equilibrium. In the case of two qubits we show that the absence of equilibrium allows the generation of steady entangled states, which is inaccessible at thermal equilibrium and is realized without any further external action on the two qubits. We first give a simple physical interpretation of the phenomenon in a specific case and then we report a detailed investigation on the dependence of the entanglement dynamics on the various physical parameters involved. Sub- and super-radiant effects are discussed, and qualitative differences in the dynamics concerning both creation and protection of entanglement according to the initial two-qubit state are pointed out. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.8081v2.pdf"}
{"id": "1311.0399", "abstract": "  The mapping between biological genotypes and phenotypes is central to the study of biological evolution. Here we introduce a rich, intuitive, and biologically realistic genotype-phenotype (GP) map, that serves as a model of self-assembling biological structures, such as protein complexes, and remains computationally and analytically tractable. Our GP map arises naturally from the self-assembly of polyomino structures on a 2D lattice and exhibits a number of properties: redundancy (genotypes vastly outnumber phenotypes), phenotype bias (genotypic redundancy varies greatly between phenotypes), genotype component disconnectivity (phenotypes consist of disconnected mutational networks) and shape space covering (most phenotypes can be reached in a small number of mutations). We also show that the mutational robustness of phenotypes scales very roughly logarithmically with phenotype redundancy and is positively correlated with phenotypic evolvability. Although our GP map describes the assembly of disconnected objects, it shares many properties with other popular GP maps for connected units, such as models for RNA secondary structure or the HP lattice model for protein tertiary structure. The remarkable fact that these important properties similarly emerge from such different models suggests the possibility that universal features underlie a much wider class of biologically realistic GP maps. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1311/1311.0399v1.pdf"}
{"id": "1311.2900", "abstract": "  Non-particulate continuum descriptions allow for computationally efficient modeling of suspension flows at scales that are inaccessible to more detailed particulate approaches. It is well known that the presence of particles influences the effective viscosity of a suspension and that this effect has thus to be accounted for in macroscopic continuum models. The present paper aims at developing a non-particulate model that reproduces not only the rheology but also the cell-induced velocity fluctuations, responsible for enhanced diffusivity. The results are obtained from a coarse-grained blood model based on the lattice Boltzmann method. The benchmark system comprises a flow between two parallel plates with one of them featuring a smooth obstacle imitating a stenosis. Appropriate boundary conditions are developed for the particulate model to generate equilibrated cell configurations mimicking an infinite channel in front of the stenosis. The averaged flow field in the bulk of the channel can be described well by a non-particulate simulation with a matched viscosity. We show that our proposed phenomenological model is capable to reproduce many features of the velocity fluctuations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1311/1311.2900v1.pdf"}
{"id": "1312.0863", "abstract": "  We study how the electromagnetic structure of the nucleon is influenced by a pion cloud. To this aim we make use of a constituent-quark model with instantaneous confinement and a pion that couples directly to the quarks. To derive the invariant 1- photon-exchange electron-nucleon scattering amplitude we employ a Poincaré- invariant coupled-channel formulation which is based on the point-form of relativistic quantum mechanics. We argue that the electromagnetic nucleon current extracted from this amplitude can be reexpressed in terms of pure hadronic degrees of freedom with the quark substructure of the pion and the nucleon being encoded in electromagnetic and strong vertex form factors. These are form factors of bare particles, i.e. eigenstates of the pure confinement problem. First numerical results for (bare) photon-nucleon and pion-nucleon form factors, which are the basic ingredients of the further calculation, are given for a simple 3-quark wave function of the nucleon. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.0863v1.pdf"}
{"id": "1312.1416", "abstract": "  The large growth of flash ADC techniques for processing signals, especially in applications of streaming data, raises issues such as data flow through an acquisition system, long-term storage, and greater complexity in data analysis. In addition, experiments that push the limits of sensitivity need to distinguish legitimate signals from noise. The use of correlation coefficients is examined to address these issues. They are found to be quite successful well into the noise region. The methods can also be extended to Field Programmable Gate Array modules for compressing the data flow and greatly enhancing the event rate capabilities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.1416v1.pdf"}
{"id": "1312.1922", "abstract": "  We present an alternative model of coronal-loop oscillations which considers that the waves are trapped in a 2D waveguide formed by the entire arcade of field lines. This differs from the standard 1D model which treats the waves as the resonant oscillations of just the visible bundle of field lines. Within the framework of our 2D model, the two types of oscillations that have been observationally identified, flare-induced waves and \"decayless\" oscillations, can both be attributed to MHD fast waves. The two components of the signal differ only because of the duration and spatial extent of the source that creates them. The flare-induced waves are generated by strong localized sources of short duration, while the decayless background can be excited by a continuous, stochastic source. Further, the oscillatory signal arising from a localized, short-duration source can be interpreted as a pattern of interference fringes produced by waves that have traveled diverse routes of various pathlengths through the waveguide. The resulting amplitude of the fringes slowly decays in time with an inverse square root dependence. The details of the interference pattern depend on the shape of the arcade and the spatial variation of the Alfvén speed. The rapid decay of this wave component, which has previously been attributed to physical damping mechanisms that remove energy from resonant oscillations, occurs as a natural consequence of the interference process without the need for local dissipation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.1922v1.pdf"}
{"id": "1312.1924", "abstract": "  The edge states of a two-dimensional topological insulator are characterized by their helicity, a very remarkable property which is related to the time-reversal symmetry and the topology of the underlying system. We theoretically investigate a Hong-Ou-Mandel like setup as a tool to probe it. Collisions of two electrons with the same spin show a Pauli dip, analogous to the one obtained in the integer quantum Hall case. Moreover, the collisions between electrons of opposite spin also lead to a dip, known as ℤ_2 dip, which is a direct consequence of the constraints imposed by time-reversal symmetry. In contrast to the integer quantum Hall case, the visibility of these dips is reduced by the presence of the additional edge channels, and crucially depends on the properties of the quantum point contact. As a unique feature of this system, we show the possibility of three-electron interference, which leads to a total suppression of the noise independently of the point contact configuration. This is assured by the peculiar interplay between Fermi statistics and topology. This work intends to extend the domain of applicability of electron quantum optics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.1924v2.pdf"}
{"id": "1401.1849", "abstract": "  Introduced in 2006 by Japaridze, cirquent calculus is a refinement of sequent calculus. The advent of cirquent calculus arose from the need for a deductive system with a more explicit ability to reason about resources. Unlike the more traditional proof-theoretic approaches that manipulate tree-like objects (formulas, sequents, etc.), cirquent calculus is based on circuit-style structures called cirquents, in which different \"peer\" (sibling, cousin, etc.) substructures may share components. It is this resource sharing mechanism to which cirquent calculus owes its novelty (and its virtues). From its inception, cirquent calculus has been paired with an abstract resource semantics. This semantics allows for reasoning about the interaction between a resource provider and a resource user, where resources are understood in the their most general and intuitive sense. Interpreting resources in a more restricted computational sense has made cirquent calculus instrumental in axiomatizing various fundamental fragments of Computability Logic, a formal theory of (interactive) computability. The so-called \"classical\" rules of cirquent calculus, in the absence of the particularly troublesome contraction rule, produce a sound and complete system CL5 for Computability Logic. In this paper, we investigate the computational complexity of CL5, showing it is Σ_2^p-complete. We also show that CL5 without the duplication rule has polynomial size proofs and is NP-complete. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.1849v4.pdf"}
{"id": "1401.3112", "abstract": "  The 3D MIMO code is a robust and efficient space-time block code (STBC) for the distributed MIMO broadcasting but suffers from high maximum-likelihood (ML) decoding complexity. In this paper, we first analyze some properties of the 3D MIMO code to show that the 3D MIMO code is fast-decodable. It is proved that the ML decoding performance can be achieved with a complexity of O(M^4.5) instead of O(M^8) in quasi static channel with M-ary square QAM modulations. Consequently, we propose a simplified ML decoder exploiting the unique properties of 3D MIMO code. Simulation results show that the proposed simplified ML decoder can achieve much lower processing time latency compared to the classical sphere decoder with Schnorr-Euchner enumeration. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.3112v1.pdf"}
{"id": "1401.5107", "abstract": "  We develop a new type and effect system based on Büchi automata to capture finite and infinite traces produced by programs in a small language which allows non-deterministic choices and infinite recursions. There are two key technical contributions: (a) an abstraction based on equivalence relations defined by the policy Büchi automaton, the Büchi abstraction; (b) a novel type and effect system to correctly capture infinite traces. We show how the Büchi abstraction fits into the abstract interpretation framework and show soundness and completeness. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.5107v1.pdf"}
{"id": "1401.7133", "abstract": "  While most of the rare-earth nickelates exhibit a temperature-driven sharp metal-insulator transition, LaNiO_3 is the only exception remaining metallic down to low temperatures. Using local density approximation as an input to dynamical mean-field calculation, metallic properties of bulk LaNiO_3 is studied. The DMFT calculations indicate that the system is a correlated Fermi liquid with an enhanced effective mass. The possibility of a pressure-driven metal-insulator transition in the system is also suggested, which can be verified experimentally. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.7133v2.pdf"}
{"id": "1401.8255", "abstract": "  Active cyber defenses based on temporal platform diversity have been proposed as way to make systems more resistant to attacks. These defenses change the properties of the platforms in order to make attacks more complicated. Unfortunately, little work has been done on measuring the effectiveness of these defenses. In this work, we use four different approaches to quantitatively analyze these defenses; an abstract analysis studies the algebraic models of a temporal platform diversity system; a set of experiments on a test bed measures the metrics of interest for the system; a game theoretic analysis studies the impact of preferential selection of platforms and derives an optimal strategy; finally, a set of simulations evaluates the metrics of interest on the models. Our results from these approaches all agree and yet are counter-intuitive. We show that although platform diversity can mitigate some attacks, it can be detrimental for others. We also illustrate that the benefit from these systems heavily depends on their threat model and that the preferential selection of platforms can achieve better protection. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.8255v1.pdf"}
{"id": "1402.0075", "abstract": "  We present a new version of a semi-analytic model of cosmological galaxy formation, incorporating a star formation law with a feedback depending on the galaxy-scale mean dust opacity and metallicity, motivated by recent observations of star formation in nearby galaxies and theoretical considerations. This new model is used to investigate the effect of such a feedback on shaping the galaxy luminosity function and its evolution. Star formation activity is significantly suppressed in dwarf galaxies by the new feedback effect, and the faint-end slope of local luminosity functions can be reproduced with a reasonable strength of supernova feedback, which is in contrast to the previous models that require a rather extreme strength of supernova feedback. Our model can also reproduce the early appearance of massive galaxies manifested in the bright-end of high redshift K-band luminosity functions. Though some of the previous models also succeeded in reproducing this, they assumed a star formation law depending on the galaxy-scale dynamical time, which is not supported by observations. We argue that the feedback depending on dust opacity (or metal column density) is essential, rather than that simply depending on gas column density, to get these results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.0075v2.pdf"}
{"id": "1402.0323", "abstract": "  Deeply Virtual Compton Scattering in the near forward kinematic region is the golden access to Generalized Parton Distributions. We studied the O(alphaS) corrections to the scattering amplitude for both spacelike and timelike kinematics relevant respectively to the leptoproduction of a real photon and to the photoproduction of a lepton pair. It turns out that these corrections are phenomenologically important and that the gluonic contributions are by no means negligible, even in the moderate energy range of JLab12 and of the COMPASS-II experiment at CERN. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.0323v1.pdf"}
{"id": "1402.5803", "abstract": "  This paper deals with sparse phase retrieval, i.e., the problem of estimating a vector from quadratic measurements under the assumption that few components are nonzero. In particular, we consider the problem of finding the sparsest vector consistent with the measurements and reformulate it as a group-sparse optimization problem with linear constraints. Then, we analyze the convex relaxation of the latter based on the minimization of a block l1-norm and show various exact recovery and stability results in the real and complex cases. Invariance to circular shifts and reflections are also discussed for real vectors measured via complex matrices. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.5803v1.pdf"}
{"id": "1402.5930", "abstract": "  We present a study of sub-pc scale radio structure of the radio galaxy 3C 84/NGC 1275 based on the Very Long Baseline Array (VLBA) data at 43 GHz. We discover a limb-brightening in the \"restarted\" jet associated with the 2005 radio outburst. In the 1990s, the jet structure was ridge-brightening rather than limb-brightening, despite the observations being done with similar angular resolution. This indicates that the transverse jet structure has changed recently. This change in the morphology shows an interesting agreement with the γ-ray flux increase, i.e., the γ-ray flux in 1990s was at least seven times lower than the current one. One plausible explanation for the limb-brightening is the velocity structure of the jet in the context of the stratified jet, which is a successful scenario to explain the γ-ray emission in some active galactic nuclei (AGNs). If this is the case, the change in apparent transverse structure might be caused by the change in the transverse velocity structure. We argue the possibility that the transition from ridge-brightening to limb-brightening is related to the γ-ray time variability on the timescale of decades. We also discuss the collimation profile of the jet. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.5930v1.pdf"}
{"id": "1402.5978", "abstract": "  We present the use of continuous-time autoregressive moving average (CARMA) models as a method for estimating the variability features of a light curve, and in particular its power spectral density (PSD). CARMA models fully account for irregular sampling and measurement errors, making them valuable for quantifying variability, forecasting and interpolating light curves, and for variability-based classification. We show that the PSD of a CARMA model can be expressed as a sum of Lorentzian functions, which makes them extremely flexible and able to model a broad range of PSDs. We present the likelihood function for light curves sampled from CARMA processes, placing them on a statistically rigorous foundation, and we present a Bayesian method to infer the probability distribution of the PSD given the measured lightcurve. Because calculation of the likelihood function scales linearly with the number of data points, CARMA modeling scales to current and future massive time-domain data sets. We conclude by applying our CARMA modeling approach to light curves for an X-ray binary, two AGN, a long-period variable star, and an RR-Lyrae star, in order to illustrate their use, applicability, and interpretation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.5978v2.pdf"}
{"id": "1403.1943", "abstract": "  We report how strategic evolution can stabilize topological states in a network of FitzHugh-Nagumo systems. The evolution follows a repeated process of adding or deleting of links between two nodes that is decided based on a threshold set for the closeness between them. This results in a need based rewiring that keeps the systems in synchrony in a single cluster or in phase locked states in different clusters. We analyse in detail the occurrence of such multi stable topological fixed points with corresponding emergent dynamical states using the frequency of occurrence of each state when evolved from a large number of initial states. We find that there is an optimum range for the threshold used in the strategy that results in maximum frequency for the stable topological states. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.1943v1.pdf"}
{"id": "1403.2482", "abstract": "  We first establish a law of large numbers and a convergence theorem in distribution to show the rate of convergence of the non-local means filter for removing Gaussian noise. We then introduce the notion of degree of similarity to measure the role of similarity for the non-local means filter. Based on the convergence theorems, we propose a patch-based weighted means filter for removing impulse noise and its mixture with Gaussian noise by combining the essential idea of the trilateral filter and that of the non-local means filter. Our experiments show that our filter is competitive compared to recently proposed methods. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.2482v1.pdf"}
{"id": "1403.3851", "abstract": "  Uniformly distributed point sets on the unit sphere with and without symmetry constraints have been found useful in many scientific and engineering applications. Here, a novel variant of the Thomson problem is proposed and formulated as an unconstrained optimization problem. While the goal of the Thomson problem is to find the minimum energy configuration of N electrons constrained on the surface of the unit sphere, this novel variant imposes a new symmetry constraint—mirror reflection symmetry with the x-y plane as the plane of symmetry. Qualitative features of the two-dimensional projection of the optimal configurations are briefly mentioned and compared to the ground-state configurations of the two dimensional system of charged particles laterally confined by a parabolic potential well. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.3851v2.pdf"}
{"id": "1403.3926", "abstract": "  We study the formation of auxin peaks in a generic class of concentration-based auxin transport models, posed on static plant tissues. Using standard asymptotic analysis we prove that, on bounded domains, auxin peaks are not formed via a Turing instability in the active transport parameter, but via simple corrections to the homogeneous steady state. When the active transport is small, the geometry of the tissue encodes the peaks' amplitude and location: peaks arise where cells have fewer neighbours, that is, at the boundary of the domain. We test our theory and perform numerical bifurcation analysis on two models which are known to generate auxin patterns for biologically plausible parameter values. In the same parameter regimes, we find that realistic tissues are capable of generating a multitude of stationary patterns, with a variable number of auxin peaks, that can be selected by different initial conditions or by quasi-static changes in the active transport parameter. The competition between active transport and production rate determines whether peaks remain localised or cover the entire domain. We relate the occurrence of localised patterns to a snaking bifurcation structure, which is known to arise in a wide variety of nonlinear media but has not yet been reported in plant models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.3926v3.pdf"}
{"id": "1403.5476", "abstract": "  We derive the analytical expressions for the thermal Casimir-Polder energy and force between a spheroidal nanoparticle above a semi-infinite material and a graphene covered interface. We analyze in detail the Casimir-Polder force between a gold nanoparticle and a single sheet of pristine graphene focusing on the impact of anisotropy. We show that the effect of anisotropy, i.e. the shape and orientation of the spheroidal nanoparticle, has a much larger influence on the force than the tunability of graphene. The effect of tuning and anisotropy both add up such that we observe a force which is between 20-50", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.5476v2.pdf"}
{"id": "1404.0277", "abstract": "  We introduce a guessing game involving a quantum channel, three parties - the sender, the receiver and an eavesdropper, Eve - and a quantum public side channel. We prove that a necessary and sufficient condition for the quantum channel to be antidegradable, is that Eve wins the game. We thus obtain a complete operational characterization of antidegradable channels in a game-theoretic framework. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.0277v2.pdf"}
{"id": "1404.0539", "abstract": "  In this paper we propose a novel theoretical framework for interpreting long-range dynamical correlations unveiled in proteins through NMR measurements. The theoretical rationale relies on the hypothesis that correlated motions in proteins may be reconstructed as large-scale, collective modes sustained by long-lived nonlinear vibrations known as discrete breathers (DB) localized at key, hot-spot sites. DBs are spatially localized modes, whose nonlinear nature hinders resonant coupling with the normal modes, thus conferring them long lifetimes as compared to normal modes. DBs have been predicted to exist in proteins, localized at few hotspot residues typically within the stiffest portions of the structure. We compute DB modes analytically in the framework of the nonlinear network model, showing that the displacement patterns of many DBs localized at key sites match to a remarkable extent the experimentally uncovered correlation blueprint. The computed dispersion relations prove that it is physically possible for some of these DBs to be excited out of thermal fluctuations at room temperature.   Based on our calculations, we speculate that transient energy redistribution among the vibrational modes in a protein might favor the emergence of DB-like bursts of long-lived energy at hot-spot sites with lifetimes in the ns range, able to sustain critical, function-encoding correlated motions. More generally, our calculations provide a novel quantitative tool to predict fold-spanning dynamical pathways of correlated residues that may be central to allosteric cross-talk in proteins. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.0539v1.pdf"}
{"id": "1404.2751", "abstract": "  A robust worldwide air-transportation network (WAN) is one that minimizes the number of stranded passengers under a sequence of airport closures. Building on top of this realistic example, here we address how spatial network robustness can profit from cooperation between local actors. We swap a series of links within a certain distance, a cooperation range, while following typical constraints of spatially embedded networks. We find that the network robustness is only improved above a critical cooperation range. Such improvement can be described in the framework of a continuum transition, where the critical exponents depend on the spatial correlation of connected nodes. For the WAN we show that, except for Australia, all continental networks fall into the same universality class. Practical implications of this result are also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.2751v2.pdf"}
{"id": "1404.3512", "abstract": "  For precise measurements with polarized neutrons high efficient spin-manipulation is required. We developed several neutron optical elements suitable for a new sophisticated setup, i.e., DC spin-turners and Larmor-accelerators which diminish thermal disturbances and depolarisation considerably. The gain in performance is exploited demonstrating violation of a Bell-like inequality for a spin-path entangled single-neutron state. The obtained value of S=2.365(13), which is much higher than previous measurements by neutron interferometry, is 28 σ above the limit of S=2 predicted by contextual hidden variable theories. The new setup is more flexible referring to state preparation and analysis, therefore new, more precise measurements can be carried out. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.3512v1.pdf"}
{"id": "1404.6421", "abstract": "  Quantum metrology studies quantum strategies which enable us to outperform their classical counterparts. In this framework, the existence of perfect classical reference frames is usually assumed. However, such ideal reference frames might not always be available. The reference frames required in metrology strategies can either degrade or become misaligned during the estimation process. We investigate how the imperfectness of reference frames leads to noise which in general affects the ultimate precision limits in measurement of physical parameters. Moreover, since quantum parameter estimation can be phrased as a quantum communication protocol between two parties, our results provide deeper insight into quantum communication protocols with misaligned reference frames. Our framework allows for the study of general noise on the efficiency of such schemes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.6421v1.pdf"}
{"id": "1405.3251", "abstract": "  Slow-fast systems on the two-torus are studied. As it was shown before, canard cycles are generic in such systems, which is in drastic contrast with the planar case. It is known that if the rotation number of the Poincare map is integer and the slow curve is connected, the number of canard limit cycles is bounded from above by the number of fold points of the slow curve. In the present paper it is proved that there are no such geometric constraints for non-integer rotation numbers: it is possible to construct generic system with as simple as possible slow curve and arbitrary many limit cycles. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.3251v3.pdf"}
{"id": "1405.3432", "abstract": "  We have classified possible transonic solutions of galactic outflows in the gravitational potential of the dark matter halo (DMH) and super massive black hole (SMBH) under the assumptions of isothermal, spherically symmetric and steady state. It is clarified that the gravity of SMBH adds a new branch of transonic solutions with the transonic point in very close proximity to the centre in addition to the outer transonic point generated by the gravity of DMH. Because these two transonic solutions have substantially different mass fluxes and starting points, these solutions may have different influences on the evolution of galaxies and the release of metals into intergalactic space. We have applied our model to the Sombrero galaxy and obtained a new type of galactic outflow: a slowly accelerated transonic outflow through the transonic point at very distant region (≃ 126 kpc). In this galaxy, previous works reported that although the trace of the galactic outflow is observed by X-ray, the gas density distribution is consistent with the hydrostatic state. We have clarified that the slowly accelerating outflow has a gas density profile quite similar to that of the hydrostatic solution in the widely spread subsonic region. Thus, the slowly accelerating transonic solution cannot be distinguished from the hydrostatic solution in the observed region (≤ 25 kpc) even if slow transonic flow exists. Our model provides a new perspective of galactic outflows and is applicable even to quiescent galaxies with inactive star formation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.3432v2.pdf"}
{"id": "1405.4482", "abstract": "  A semiconductor model of rocks is shown to describe unipolar magnetic pulses, a phenomenon that has been observed prior to earthquakes. These pulses are observable because their extremely long wavelength allows them to pass through the Earth's crust. Interestingly, the source of these pulses may be triangulated to pinpoint locations where stress is building deep within the crust. We couple a semiconductor drift-diffusion model to a magnetic field in order to describe the electromagnetic effects associated with electrical currents flowing within rocks. The resulting system of equations is solved numerically and it is seen that a volume of rock may act as a diode that produces transient currents when it switches bias. These unidirectional currents are expected to produce transient unipolar magnetic pulses similar in form, amplitude, and duration to those observed before earthquakes, and this suggests that the pulses could be the result of geophysical semiconductor processes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.4482v1.pdf"}
{"id": "1405.5326", "abstract": "  In anonymous broadcast, one or more parties want to anonymously send messages to all parties. This problem is increasingly important as a black-box in many privacy-preserving applications such as anonymous communication, distributed auctions, and multi-party computation. In this paper, we design decentralized protocols for anonymous broadcast that require each party to send (and compute) a polylogarithmic number of bits (and operations) per anonymous bit delivered with O(log n) rounds of communication. Our protocol is provably secure against traffic analysis, does not require any trusted party, and is completely load-balanced. The protocol tolerates up to n/6 statically-scheduled Byzantine parties that are controlled by a computationally unbounded adversary. Our main strategy for achieving scalability is to perform local communications (and computations) among a logarithmic number of parties. We provide simulation results to show that our protocol improves significantly over previous work. We finally show that using a common cryptographic tool in our protocol one can achieve practical results for anonymous broadcast. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.5326v1.pdf"}
{"id": "1405.6983", "abstract": "  We present the first device-independent quantum cryptography protocol for continuous variables. Our scheme is based on the Gottesman-Kitaev-Preskill encoding scheme whereby a qubit is embedded in the infinite-dimensional space of a quantum harmonic oscillator. The novel application of discrete-variable device-independent quantum key distribution to this encoding enables a continuous-variable analogue. Since the security of this protocol is based on discrete-variables we inherit by default security against collective attacks and, under certain memoryless assumptions, coherent attacks. We find that our protocol is valid over the same distances as its discrete-variable counterpart, except that we are able to take advantage of high efficiency commercially available detectors where, for the most part, only homodyne detection is required. This offers the potential of removing the difficulty in closing the loopholes associated with Bell inequalities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.6983v1.pdf"}
{"id": "1406.1409", "abstract": "  The 112,120Sn(gamma,gamma') reactions below the neutron separation energies have been studied at the superconducting Darmstadt electron linear accelerator S-DALINAC for different endpoint energies of the incident bremsstrahlung spectrum. Dipole strength distributions are extracted for 112Sn up to 9.5 MeV and for 120Sn up to 9.1 MeV. A concentration of dipole excitations is observed between 5 and 8 MeV in both nuclei. Missing strength due to unobserved decays to excited states is estimated in a statistical model. A fluctuation analysis is applied to the photon scattering spectra to extract the amount of the unresolved strength hidden in background due to fragmentation. The strength distributions are discussed within different model approaches such as the quasiparticle-phonon model and the relativistic time blocking approximation allowing for an inclusion of complex configurations beyond the initial particle-hole states. While a satisfactory description of the fragmentation can be achieved for sufficently large model spaces, the predicted centroids and total electric dipole strengths for stable tin isotopes strongly depend on the assumptions about the underlying mean field. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.1409v3.pdf"}
{"id": "1406.2598", "abstract": "  We investigate the dependence of the structural phase transitions in an infinite quasi-one-dimensional system of repulsively interacting particles on the profile of the confining channel. Three different functional expressions for the confinement potential related to real experimental systems are used that can be tuned continuously from a parabolic to a hard-wall potential in order to find a thorough understanding of the ordering of the chain-like structure transitions. We resolve the longstanding issue why the most theories predicted a 1-2-4-3-4 sequence of chain configurations with increasing density, while some experiments found the 1-2-3-4 sequence. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.2598v1.pdf"}
{"id": "1406.7504", "abstract": "  We identify the mechanism behind the existence of intensity induced chimera states in globally coupled oscillators. We find that the effect of intensity in the system is to cause multistability by increasing the number of fixed points. This in turn increases the number of multistable attractors and we find that their stability is determined by the strength of coupling . This causes the coexistence of different collective states in the system depending upon the initial state. We demonstrate that intensity induced chimera is generic to both periodic and chaotic systems. We have discussed possible applications of our results to real world systems like the brain and spin torque nano oscillators. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.7504v2.pdf"}
{"id": "1407.6093", "abstract": "  Complex bands k⃗^⊥(E) in a semiconductor crystal, along a general direction n⃗, can be computed by casting Schrödinger's equation as a generalized polynomial eigenvalue problem. When working with primitive lattice vectors, the order of this eigenvalue problem can grow large for arbitrary n⃗. It is however possible to always choose a set of non-primitive lattice vectors such that the eigenvalue problem is restricted to be quadratic. The complex bands so obtained need to be unfolded onto the primitive Brillouin zone. In this paper, we present a unified method to unfold real and complex bands. Our method ensures that the measure associated with the projections of the non-primary wavefunction onto all candidate primary wavefunctions is invariant with respect to the energy E. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.6093v1.pdf"}
{"id": "1407.8236", "abstract": "  During the 2014 Summer Conferences, both ATLAS and CMS Collaborations of the LHC experiments have demonstrated tremendous efforts in treatment of data and processing more data such that most data on signal strengths have improved; especially the diphoton and fermionic modes of both experiments. Here in this note we perform an update to our previous model-independent Higgs precision analysis – Higgcision. We found the followings: (i) the uncertainties on most couplings shrink about 10–20", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.8236v2.pdf"}
{"id": "1408.2532", "abstract": "  The collective expansion of matter created in collisions of heavy-ions, ranging from collision energies of tens of MeV to a few TeV per nucleon pair, proved to be one of the best probes to study the detailed properties of these unknown states of matter. Collective expansion originates from the initial pressure gradients in the created hot and dense matter. These pressure gradients transform the initial spatial deformations and inhomogeneities of the created matter into momentum anisotropies of the final state particle production, which we call anisotropic flow. These momentum anisotropies are experimentally characterised by so-called flow harmonics. In this paper I review ALICE measurements of the flow harmonics at the CERN Large Hadron Collider and discuss some of the open questions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.2532v2.pdf"}
{"id": "1408.3631", "abstract": "  Application of the most robust method of measuring black hole masses, spatially resolved kinematics of gas and stars, is presently limited to nearby galaxies. The Atacama Large Millimeter/sub-millimeter Array (ALMA) and thirty meter class telescopes (the Thirty Meter Telescope, the Giant Magellan Telescope, and the European Extremely Large Telescope) with milli-arcsecond resolution are expected to extend such measurements to larger distances. Here, we study the possibility of exploiting the angular magnification provided by strong gravitational lensing to measure black hole masses at high redshifts (z  1-6), using resolved gas kinematics with these instruments. We show that in  15", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.3631v1.pdf"}
{"id": "1409.1083", "abstract": "  Background: The time-dependent Hartree-Fock (TDHF) theory has been successful in describing low-energy heavy ion collisions. Recently, we have shown that multinucleon transfer processes can be reasonably described in the TDHF theory combined with the particle-number projection technique. Purpose: In this work, we propose a theoretical framework to analyze properties of reaction products in TDHF calculations. Methods: TDHF calculation in three-dimensional Cartesian grid representation combined with particle number projection method. Results: We develop a theoretical framework to calculate expectation values of operators in the TDHF wave function after collision with the particle-number projection. To show how our method works in practice, the method is applied to ^24O+^16O collisions for two quantities, angular momentum and excitation energy. The analyses revealed following features of the reaction: The nucleon removal proceeds gently, leaving small values of angular momentum and excitation energy in nucleon removed nuclei. Contrarily, nuclei receiving nucleons show expectation values of angular momentum and excitation energy which increase as the incident energy increases. Conclusions: We have developed a formalism to analyze properties of fragment nuclei in the TDHF theory combined with the particle-number projection technique. The method will be useful for microscopic investigations of reaction mechanisms in low-energy heavy ion collisions as well as for evaluating effects of particle evaporation on multinucleon transfer cross sections. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1409/1409.1083v2.pdf"}
{"id": "1409.3613", "abstract": "  Long-range correlated processes are ubiquitous, ranging from climate variables to financial time series. One paradigmatic example for such processes is fractional Brownian motion (fBm). In this work, we highlight the potentials and conceptual as well as practical limitations when applying the recently proposed recurrence network (RN) approach to fBm and related stochastic processes. In particular, we demonstrate that the results of a previous application of RN analysis to fBm (Liu et al., Phys. Rev. E 89, 032814 (2014)) are mainly due to an inappropriate treatment disregarding the intrinsic non-stationarity of such processes. Complementarily, we analyze some RN properties of the closely related stationary fractional Gaussian noise (fGn) processes and find that the resulting network properties are well-defined and behave as one would expect from basic conceptual considerations. Our results demonstrate that RN analysis can indeed provide meaningful results for stationary stochastic processes, given a proper selection of its intrinsic methodological parameters, whereas it is prone to fail to uniquely retrieve RN properties for non-stationary stochastic processes like fBm. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1409/1409.3613v1.pdf"}
{"id": "1409.4564", "abstract": "  An experimental method to characterize the crosstalk and afterpulsing in silicon photomultipliers has been developed and applied to two detectors fabricated by Hamamatsu. An analytical model of optical crosstalk that we presented in a previous publication has been compared with new measurements, confirming our results. Progresses on a statistical model to describe afterpulsing and delayed crosstalk are also shown and compared with preliminary experimental data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1409/1409.4564v1.pdf"}
{"id": "1409.4763", "abstract": "  We investigate the sensitivity of nonintegrable large-spin quantum lattices to small perturbations with a particular focus on the time reversal experiments known in statistical physics as \"Loschmidt echoes\" and in nuclear magnetic resonance (NMR) as \"magic echoes\". Our numerical simulations of quantum spin-71/2 clusters indicate that there is a regime, where Loschmidt echoes exhibit nearly exponential sensitivity to small perturbations with characteristic constant approximately equal to twice the value of the largest Lyapunov exponent of the corresponding classical spin clusters. The above theoretical results are verifiable by NMR experiments on solids containing large-spin nuclei. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1409/1409.4763v1.pdf"}
{"id": "1409.5517", "abstract": "  In this paper, we study the inverse problem for a class of abstract ultraparabolic equations which is well-known to be ill-posed. We employ some elementary results of semi-group theory to present the formula of solution, then show the instability cause. Since the solution exhibits unstable dependence on the given data functions, we propose a new regularization method to stabilize the solution. then obtain the error estimate. A numerical example shows that the method is efficient and feasible. This work slightly extends to the earlier results in Zouyed et al. <cit.> (2014). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1409/1409.5517v1.pdf"}
{"id": "1409.6733", "abstract": "  Our knowledge of the dynamics and masses of galaxies in the Local Group has long been limited by the fact that only line-of-sight velocities were observationally accessible. This introduces significant degeneracies in dynamical models, which can only be resolved by measuring also the velocity components perpendicular to the line of sight. However, beyond the solar neighborhood, the corresponding proper motions have generally been too small to measure. This has changed dramatically over the past decade, especially due to the angular resolution and stability available on the Hubble Space Telescope. Proper motions can now be reliably measured throughout the Local Group, as illustrated by, e.g., the work of the HSTPROMO collaboration. In this review, I summarize the importance of proper motions for Local Group science, and I describe the current and future observational approaches and facilities available to measure proper motions. I highlight recent results on various Milky Way populations (globular clusters, the bulge, the metal-poor halo, hypervelocity stars, and tidal streams), dwarf satellite galaxies, the Magellanic Clouds and the Andromeda System. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1409/1409.6733v1.pdf"}
{"id": "1410.3347", "abstract": "  Motivated by the Galactic Center gamma-ray excess in the Fermi-LAT data, we study the signatures of a class of tau portal dark matter (DM) models where DM particles preferentially couple to tau leptons at the LHC. We consider the constraints from the DM direct detection and investigate the sensitivity of the LHC to di-tau plus missing energy signatures. We find that the LHC with a high luminosity of 3000 fb^-1 can test the tau portal DM models with fermionic mediators in the mass range of 120∼450 GeV. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.3347v1.pdf"}
{"id": "1410.3672", "abstract": "  We present a scheme to realize versatile quantum networks by cascading several four-wave mixing (FWM) processes in warm rubidium vapors. FWM is an efficient χ^(3) nonlinear process, already used as a resource for multimode quantum state generation and which has been proved to be a promising candidate for applications to quantum information processing. We analyze theoretically the multimode output of cascaded FWM systems, derive its independent squeezed modes and show how, with phase controlled homodyne detection and digital post-processing, they can be turned into a versatile source of continuous variable cluster states. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.3672v2.pdf"}
{"id": "1410.5006", "abstract": "  We study the stationary solution of an atomic Bose-Einstein condensate coupled coherently to a molecular condensate with both repulsive and attractive interspecies interactions confined in an isotropic harmonic trap. We use the Thomas-Fermi approximation and find four kinds of analytical solution for the cases. These analytical solutions are adopted as trial function for the diffusive numerical solution of the Gross-Pitaevskii equations. For the repulsive interspecies interaction, the case in which the atomic and molecular wavefunctions are out-phase, the densities have similar profiles for both methods, however, the case where the wavefunctions are in-phase, there are considerable difference between the density profiles. For the attractive interspecies interaction, there are two cases in the Thomas Fermi approximation where the wavefunctions are in-phase. One of them has numerical solution that agree with the approximation and the other does not have corresponding numerical solution. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.5006v1.pdf"}
{"id": "1410.5445", "abstract": "  Majorana qubits offer a promising way to store and manipulate quantum information by encoding it into the state of Majorana zero modes. As the information is stored in a topological property of the system, local noise cannot lead to decoherence. Manipulation of the information is achieved by braiding the zero modes. The measurement, however, is challenging as the information is well hidden and thus inherently hard to access. Here, we discuss a setup for measuring the state of a Majorana qubit by employing standard tools of microwave engineering. The basic physical effect that we employ is the fact that a voltage-biased Josephson junction hosting Majorana fermions allows photons to be emitted and absorbed at half the Josephson frequency. We show that in the dispersive regime, our setup allows us to perform a quantum nondemolition measurement and to reach the quantum limit. An appealing feature of our setup is that the interaction of the Majorana qubit with the measurement device can be turned on and off at will by changing the dc bias of the junction. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.5445v2.pdf"}
{"id": "1411.0907", "abstract": "  This paper presents a new approach to behavioral-social dynamics of pedestrian crowds by suitable development of methods of the kinetic theory. It is shown how heterogeneous individual behaviors can modify the collective dynamics, as well as how local unusual behaviors can propagate in the crowd. The main feature of this approach is a detailed analysis of the interactions between dynamics and social behaviors. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1411/1411.0907v1.pdf"}
{"id": "1411.3030", "abstract": "  A general formula of the symmetry energy for many-body interaction is proposed and the commonly used two-body interaction symmetry energy is recovered. Within Landau's theory (Lt), we generalize two equations of state (EoS) CCSδ3 and CCSδ5 to asymmetric nuclear matter. We assume that the density and density difference between protons and neutrons divided by their sum are order parameters. We use different EoS to study neutron stars by solving the TOV equations. We demonstrate that different EoS give different mass and radius relation for neutron stars even when they have exactly the same ground state (gs) properties (E/A, ρ_0, K, S, L and K_sym). Furthermore, for one EoS we change K_sym and fix all the other gs parameters. We find that for some K_sym the EoS becomes unstable at high density even for neutron matter. This suggests that a neutron star (NS) can exist below and above the instability region but in different states: a quark gluon plasma (QGP) at high density and baryonic matter at low density. If the star's central density is in the instability region, then we associate these conditions to the occurrence of Supernovae (SN). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1411/1411.3030v1.pdf"}
{"id": "1412.3353", "abstract": "  The heterogeneity of reaction fluxes present in a metabolic network within a single flux state can be exploited to construct the so-called backbone as a reduced version of metabolism. The backbone maintains all significant fluxes producing or consuming metabolites while displaying a substantially decreased number of interconnections and, hence, it becomes a useful tool to extract primary metabolic routes. Here, we disclose the metabolic backbone of Escherichia coli using the computationally predicted fluxes which maximize the growth rate in glucose minimal medium, and we compare it with the backbone of Mycoplasma pneumoniae, a much simpler organism. We find that the central core in both backbones is mainly composed of reactions in ancient pathways, still playing at present a key role in energy metabolism. In E. coli, the analysis of the backbone reveals that the synthesis of nucleotides and the metabolism of lipids form smaller cores which rely critically on energy metabolism; but not conversely. At the same time, an analysis of the dependence of this backbone on media composition leads to the identification of pathways sensitive to environmental changes. The metabolic backbone of an organism is thus useful to trace simultaneously both its evolution and adaptation fingerprints. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.3353v4.pdf"}
{"id": "1412.4846", "abstract": "  Human language, as a typical complex system, its organization and evolution is an attractive topic for both physical and cultural researchers. In this paper, we present the first exhaustive analysis of the text organization of human speech. Two important results are that: (i) the construction and organization of spoken language can be characterized as Zipf's law and Heaps' law, as observed in written texts; (ii) word frequency vs. rank distribution and the growth of distinct words with the increase of text length shows significant differences between book and speech. In speech word frequency distribution are more concentrated on higher frequency words, and the emergence of new words decreases much rapidly when the content length grows. Based on these observations, a new generalized model is proposed to explain these complex dynamical behaviors and the differences between speech and book. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.4846v2.pdf"}
{"id": "1412.6185", "abstract": "  Exponential varieties arise from exponential families in statistics. These real algebraic varieties have strong positivity and convexity properties, familiar from toric varieties and their moment maps. Among them are varieties of inverses of symmetric matrices satisfying linear constraints. This class includes Gaussian graphical models. We develop a general theory of exponential varieties. These are derived from hyperbolic polynomials and their integral representations. We compare the multidegrees and ML degrees of the gradient map for hyperbolic polynomials. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.6185v2.pdf"}
{"id": "1412.8269", "abstract": "  In this paper, we define (reduced) homeology groups and (reduced) cohomeology groups on finite simpicial complexes and prove that these groups are PL homeomorphsm invariants of polyhedra, while they are not homotopy invariants. So these groups can reflect some information that (co)homology groups can not tell. We also define homeotopy type of polyhedra which is finer than homotopy type but coarser than homeomorphism class, and prove that (co)homeology groups are actually homeotopy invariants. In the last section of this paper, we give a geometric description of some special (co)homeology groups. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.8269v1.pdf"}
{"id": "1501.00059", "abstract": "  It is generally expected that adding light sterile species would increase the effective number of neutrinos, N_eff. In this paper we discuss a scenario that N_eff can actually decrease due to the neutrino oscillation effect if sterile neutrinos have self-interactions. We specifically focus on the eV mass range, as suggested by the neutrino anomalies. With large self-interactions, sterile neutrinos are not fully thermalized in the early Universe because of the suppressed effective mixing angle or matter effect. As the Universe cools down, flavor equilibrium between active and sterile species can be reached after big bang nucleosynthesis (BBN) epoch, but leading to a decrease of N_eff. In such a scenario, we also show that the conflict with cosmological mass bounds on the additional sterile neutrinos can be relaxed further when more light species are introduced. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.00059v3.pdf"}
{"id": "1501.02279", "abstract": "  Vibrational energies and wave functions of the triplet state of the H3+ ion have been determined. In the calculations, the ground and first excited triplet electronic states are included as well as the non-Born-Oppenheimer coupling between them. A diabatization procedure transforming the two adiabatic ab initio potential energy surfaces of the triplet-H3+ state into a 2x2 matrix is employed. The diabatization takes into account the non-Born-Oppenheimer coupling and the effect of the geometrical phase due to the conical intersection between the two adiabatic potential surfaces. The results are compared to the calculation involving only the lowest adiabatic potential energy surface of the triplet-H3+ ion and neglecting the geometrical phase. The energy difference between results with and without the non-adiabatic coupling and the geometrical phase is about a wave number for the lowest vibrational levels. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.02279v1.pdf"}
{"id": "1501.04004", "abstract": "  We consider cosmological modelling in f(R) theories of gravity, using both top-down and bottom-up constructions. The top-down models are based on Robertson-Walker geometries, and the bottom-up constructions are built by patching together sub-horizon-sized regions of perturbed Minkowski space. Our results suggest that these theories do not provide a theoretically attractive alternative to the standard general relativistic cosmology. We find that the only f(R) theories that can admit an observationally viable weak-field limit have large-scale expansions that are observationally indistinguishable from the Friedmann solutions of General Relativity with Λ. Such theories do not alleviate any of the difficulties associated with Λ, and cannot produce any new behaviour in the cosmological expansion without simultaneously destroying the Newtonian approximation to gravity on small scales. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.04004v2.pdf"}
{"id": "1501.04118", "abstract": "  We present luminosity functions derived from a spectroscopic survey of AGN selected from Spitzer Space Telescope imaging surveys. Selection in the mid-infrared is significantly less affected by dust obscuration. We can thus compare the luminosity functions of the obscured and unobscured AGN in a more reliable fashion than by using optical or X-ray data alone. We find that the AGN luminosity function can be well described by a broken power-law model in which the break luminosity decreases with redshift. At high redshifts (z>1.6), we find significantly more AGN at a given bolometric luminosity than found by either optical quasar surveys or hard X-ray surveys. The fraction of obscured AGN decreases rapidly with increasing AGN luminosity, but, at least at high redshifts, appears to remain at ≈ 50% even at bolometric luminosities ∼ 10^14L_⊙. The data support a picture in which the obscured and unobscured populations evolve differently, with some evidence that high luminosity obscured quasars peak in space density at a higher redshift than their unobscured counterparts. The amount of accretion energy in the Universe estimated from this work suggests that AGN contribute about 12% to the total radiation intensity of the Universe, and a high radiative accretion efficiency ≈ 0.18^+0.12_-0.07 is required to match current estimates of the local mass density in black holes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.04118v1.pdf"}
{"id": "1501.05526", "abstract": "  In this work, we propose a mixed finite element method for solving elliptic multiscale problems based on a localized orthogonal decomposition (LOD) of Raviart-Thomas finite element spaces. It requires to solve local problems in small patches around the elements of a coarse grid. These computations can be perfectly parallelized and are cheap to perform. Using the results of these patch problems, we construct a low dimensional multiscale mixed finite element space with very high approximation properties. This space can be used for solving the original saddle point problem in an efficient way. We prove convergence of our approach, independent of structural assumptions or scale separation. Finally, we demonstrate the applicability of our method by presenting a variety of numerical experiments, including a comparison with an MsFEM approach. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.05526v3.pdf"}
{"id": "1502.01489", "abstract": "  We consider a process to create quasi long-range quantum discord between the non-interacting end spins of a quantum spin chain, with the end spins weakly coupled to the bulk of the chain. The process is not only capable of creating long-range quantum correlation but the latter remains frozen, when certain weak end-couplings are adiabatically varied below certain thresholds. We term this phenomenon as adiabatic freezing of quantum correlation. We observe that the freezing is robust to moderate thermal fluctuations and is intrinsically related to the cooperative properties of the quantum spin chain. In particular, we find that the energy gap of the system remains frozen for these adiabatic variations, and moreover, considering the end spins as probes, we show that the interval of freezing can detect the anisotropy transition in quantum XY spin chains. Importantly, the adiabatic freezing of long-range quantum correlations can be simulated with contemporary experimental techniques. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.01489v2.pdf"}
{"id": "1502.03171", "abstract": "  Among the more than 1000 gamma-ray bursts observed by the Fermi Gamma-ray Space Telescope, a large fraction show narrow and hard spectra inconsistent with non-thermal emission, signifying optically thick emission from the photosphere. However, only a few of these bursts have spectra consistent with a pure Planck function. We will discuss the observational features of photospheric emission in these GRBs as well as in the ones showing multi-component spectra. We interpret the observations in light of models of subphotospheric dissipation, geometrical broadening and multi-zone emission, and show what we can learn about the dissipation mechanism and properties of GRB jets. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.03171v1.pdf"}
{"id": "1502.06863", "abstract": "  We address dissipation effects on the non-equilibrium quantum dynamics of an ensemble of spins-1/2 coupled via an Ising interaction. Dissipation is modeled by a (ohmic) bath of harmonic oscillators at zero temperature and correspond either to the sound modes of a one-dimensional Bose-Einstein (quasi-)condensate or to the zero-point fluctuations of a long transmission line. We consider the dimer comprising two spins and the quantum Ising chain with long-range interactions, and develop a (mathematically and numerically) exact stochastic approach to address non-equilibrium protocols in the presence of an environment. For the two spin case, we first investigate the dissipative quantum phase transition induced by the environment through quantum quenches, and study the effect of the environment on the synchronization properties. Then, we address Landau-Zener-Stueckelberg-Majorana protocols for two spins, and for the spin array. In this latter case, we adopt a stochastic mean-field point of view and present a Kibble-Zurek type argument to account for interaction effects in the lattice. Such dissipative quantum spin arrays can be realized in ultra-cold atoms, trapped ions, mesoscopic systems, and are related to Kondo lattice models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.06863v4.pdf"}
{"id": "1503.00213", "abstract": "  We propose a novel numerical approach for nonlocal diffusion equations [8] with integrable kernels, based on the relationship between the backward Kolmogorov equation and backward stochastic differential equations (BSDEs) driven by Lèvy processes with jumps. The nonlocal diffusion problem under consideration is converted to a BSDE,for which numerical schemes are developed and applied directly. As a stochastic approach, the proposed method does not require the solution of linear systems, which allows for embarrassingly parallel implementations and also enables adaptive approximation techniques to be incorporated in a straightforward fashion. Moreover, our method is more accurate than classic stochastic approaches due to the use of high-order temporal and spatial discretization schemes. In addition, our approach can handle a broad class of problems with general nonlinear forcing terms as long as they are globally Lipchitz continuous. Rigorous error analysis of the new method is provided as several numerical examples that illustrate the effectiveness and efficiency of the proposed approach. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.00213v2.pdf"}
{"id": "1503.00284", "abstract": "  The charge density response function and the exchange hole are closely related to each other via the fundamental fluctuation-dissipation theorem of physics. A simple approximate model of the static response function is visually compared on several examples in order to demonstrate this relationship. This study is completed by illustrating the well-known isomorphism between the exchange hole and the square of the dominant localized orbital lying in the space region of the reference point of the exchange hole function. The implications of these relationships for the interpretation of common chemical concepts, such as delocalization, are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.00284v1.pdf"}
{"id": "1503.01680", "abstract": "  We probe the mechanisms at work in the build-up of thermoreversible gel networks, with the help of hybrid gelatin gels containing a controlled density of irreversible, covalent crosslinks (CL), which we quench below the physical gelation temperature. The detailed analysis of the dependence on covalent crosslink density of both the shear modulus and optical activity evolutions with time after quench enables us to identify two stages of the physical gelation process, separated by a temperature dependent crossover modulus: (i) an early nucleation regime during which rearrangements of the triple-helix CL play a negligible role, (ii) a late, logarithmic aging one, which is preserved, though slowed down, in the presence of irreversible CL. We show that aging is fully controlled by rearrangements and discuss the implication of our results in terms of the switch from an early, local dynamics to a late, cooperative long-range one. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.01680v1.pdf"}
{"id": "1503.02400", "abstract": "  A new averaging method linking discrete to continuum variables of granular materials is developed and used to derive average balance equations. Its novelty lies in the choice of the decomposition between mean values and fluctuations of properties which takes into account the effect of gradients. Thanks to a local homogeneity hypothesis, whose validity is discussed, simplified balance equations are obtained. This original approach solves the problem of dependence of some variables on the size of the averaging domain obtained in previous approaches which can lead to huge relative errors (several hundred percentages). It also clearly separates affine and nonaffine fields in the balance equations. The resulting energy cascade picture is discussed, with a particular focus on unidirectional steady and fully developed flows for which it appears that the contact terms are dissipated locally unlike the kinetic terms which contribute to a nonlocal balance. Application of the method is demonstrated in the determination of the macroscopic properties such as volume fraction, velocity, stress, and energy of a simple shear flow, where the discrete results are generated by means of discrete particle simulation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.02400v1.pdf"}
{"id": "1503.02404", "abstract": "  The Taurus-Auriga molecular complex (TMC) is the main laboratory for the study of low mass star formation. The density and properties of interstellar dust are expected to vary across the TMC. These variations trace important processes such as dust nucleation or the magnetic field coupling with the cloud. In this article, we show how the combination of near ultraviolet (NUV) and infrared (IR) photometry can be used to derive the strength of the 2175 Å bump and thus any enhancement in the abundance of small dust grains and PAHs in the dust grains size distribution. This technique is applied to the envelope of the TMC, mapped by the GALEX All Sky Survey (AIS). UV and IR photometric data have been retrieved from the GALEX-AIS and the 2MASS catalogues. NUV and K-band star counts have been used to identify the areas in the cloud envelope where the 2175 Å bump is weaker than in the diffuse ISM namely, the low column density extensions of L1495, L1498 and L1524 in Taurus, L1545, L1548, L1519, L1513 in Auriga and L1482-83 in the California region. This finding agrees with previous results on dust evolution derived from Spitzer data and suggests that dust grains begin to decouple from the environmental galactic magnetic field already in the envelope. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.02404v1.pdf"}
{"id": "1503.05257", "abstract": "  We report laboratory measurements of the absorption coefficient of solid para-H2, within the wavelength range from 1 to 16.7 micron, at high spectral resolution. In addition to the narrow rovibrational lines of H2 which are familiar from gas phase spectroscopy, the data manifest double transitions and broad phonon branches that are characteristic specifically of hydrogen in the solid phase. These transitions are of interest because they provide a spectral signature which is independent of the impurity content of the matrix. We have used our data, in combination with a model of the ultraviolet absorptions of the H2 molecule, to construct the dielectric function of solid para-H2 over a broad range of frequencies. Our results will be useful in determining the electromagnetic response of small particles of solid hydrogen. The dielectric function makes it clear that pure H2 dust would contribute to IR extinction predominantly by scattering starlight, rather than absorbing it, and the characteristic IR absorption spectrum of the hydrogen matrix itself will be difficult to observe. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.05257v1.pdf"}
{"id": "1504.00620", "abstract": "  Time-reversible symplectic methods, which are precisely compatible with Liouville's phase-volume-conservation theorem, are often recommended for computational simulations of Hamiltonian mechanics. Lack of energy drift is an apparent advantage of such methods. But all numerical methods are susceptible to Lyapunov instability, which severely limits the maximum time for which chaotic solutions can be \"accurate\". The \"advantages\" of higher-order methods are lost rapidly for typical chaotic Hamiltonians. We illustrate these difficulties for a useful reproducible test case, the two-dimensional one-particle cell model with specially smooth forces. This Hamiltonian problem is chaotic and occurs on a three-dimensional constant-energy shell, the minimum dimension for chaos. We benchmark the problem with quadruple-precision trajectories using the fourth-order Candy-Rozmus, fifth-order Runge-Kutta, and eighth-order Schlier-Seiter-Teloy integrators. We compare the last, most-accurate particle trajectories to those from six double-precision algorithms, four symplectic and two Runge-Kutta. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.00620v2.pdf"}
{"id": "1504.01662", "abstract": "  The direction-of-arrival (DOA) estimation problem involves the localization of a few sources from a limited number of observations on an array of sensors, thus it can be formulated as a sparse signal reconstruction problem and solved efficiently with compressive sensing (CS) to achieve high-resolution imaging. On a discrete angular grid, the CS reconstruction degrades due to basis mismatch when the DOAs do not coincide with the angular directions on the grid. To overcome this limitation, a continuous formulation of the DOA problem is employed and an optimization procedure is introduced, which promotes sparsity on a continuous optimization variable. The DOA estimation problem with infinitely many unknowns, i.e., source locations and amplitudes, is solved over a few optimization variables with semidefinite programming. The grid-free CS reconstruction provides high-resolution imaging even with non-uniform arrays, single-snapshot data and under noisy conditions as demonstrated on experimental towed array data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.01662v1.pdf"}
{"id": "1504.03841", "abstract": "  We present a simple on-chip electronic thermometer with the potential to operate down to 1 mK. It is based on transport through a single normal-metal - superconductor tunnel junction with rapidly widening leads. The current through the junction is determined by the temperature of the normal electrode that is efficiently thermalized to the phonon bath, and it is virtually insensitive to the temperature of the superconductor, even when the latter is relatively far from equilibrium. We demonstrate here the operation of the device down to 7 mK and present a systematic thermal analysis. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.03841v2.pdf"}
{"id": "1504.04066", "abstract": "  An on-going effort in the characterization of exoplanetary systems is the accurate determination of host star properties. This effort extends to the relatively bright host stars of planets discovered with the radial velocity method. The Transit Ephemeris Refinement and Monitoring Survey (TERMS) is aiding in these efforts as part of its observational campaign for exoplanet host stars. One of the first known systems is that of 70 Virginis, which harbors a jovian planet in an eccentric orbit. Here we present a complete characterization of this system with a compilation of TERMS photometry, spectroscopy, and interferometry. We provide fundamental properties of the host star through direct interferometric measurements of the radius (1.5% uncertainty) and through spectroscopic analysis. We combined 59 new Keck HIRES radial velocity measurements with the 169 previously published from the ELODIE, Hamilton, and HIRES spectrographs, to calculate a refined orbital solution and construct a transit ephemeris for the planet. These newly determined system characteristics are used to describe the Habitable Zone of the system with a discussion of possible additional planets and related stability simulations. Finally, we present 19 years of precision robotic photometry that constrain stellar activity and rule out central planetary transits for a Jupiter-radius planet at the 5σ level, with reduced significance down to an impact parameter of b = 0.95. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.04066v1.pdf"}
{"id": "1504.05682", "abstract": "  Mesoscopic thermoelectric heat engine is much anticipated as a device that allows us to utilize with high efficiency wasted heat inaccessible by conventional heat engines. However, the derivation of the heat current in this engine seems to be either not general or described too briefly, even inappropriate in some cases. In this paper, we give a clear-cut derivation of the heat current of the engine with suitable assumptions beyond the linear-response regime. It resolves the confusion in the definition of the heat current in the linear-response regime. After verifying that we can construct the same formalism as that of the cyclic engine, we find the following two interesting results within the Landauer-Büttiker formalism: the efficiency of the mesoscopic thermoelectric engine reaches the Carnot efficiency if and only if the transmission probability is finite at a specific energy and zero otherwise; the unitarity of the transmission probability guarantees the second law of thermodynamics, invalidating Benenti et al.'s argument in the linear-response regime that one could obtain a finite power with the Carnot efficiency under a broken time-reversal symmetry. These results demonstrate how quantum mechanics constraints thermodynamics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.05682v4.pdf"}
{"id": "1504.06553", "abstract": "  Oscillations lie at the core of many biological processes, from the cell cycle, to circadian oscillations and developmental processes. Time-keeping mechanisms are essential to enable organisms to adapt to varying conditions in environmental cycles, from day/night to seasonal. Transcriptional regulatory networks are one of the mechanisms behind these biological oscillations. However, while identifying cyclically expressed genes from time series measurements is relatively easy, determining the structure of the interaction network underpinning the oscillation is a far more challenging problem. Here, we explicitly leverage the oscillatory nature of the transcriptional signals and present a method for reconstructing network interactions tailored to this special but important class of genetic circuits. Our method is based on projecting the signal onto a set of oscillatory basis functions using a Discrete Fourier Transform. We build a Bayesian Hierarchical model within a frequency domain linear model in order to enforce sparsity and incorporate prior knowledge about the network structure. Experiments on real and simulated data show that the method can lead to substantial improvements over competing approaches if the oscillatory assumption is met, and remains competitive also in cases it is not. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.06553v1.pdf"}
{"id": "1504.08189", "abstract": "  In this work we study a microtubule (MT) model, whose length is regulated by the action of processive kinesin motors. We treat the case of infinite processivity, i.e. particle exchange in the bulk is neglected. The exact results can be obtained for model parameters which correspond to a finite length of the MT. In contrast to the model with particle exchange we find that the lengths of the MT are exponentially distributed in this parameter regime. The remaining parameter space of the model, which corresponds to diverging MT lengths, is analyzed by means of extensive Monte Carlo simulations and a macroscopic approach. For divergent MTs we find a complex structure of the phase diagram in terms of shapes of the density profile. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.08189v2.pdf"}
{"id": "1505.01367", "abstract": "  Software testing uses wide range of different tools to enhance the complicated process of defining quality of the system under test. Formal Concept Analysis (FCA) provides us with algorithms of deriving formal ontology from a set of objects and their attributes. With the use of FCA we can considerably improve the efficiency of test case derivation. Moreover, an FCA-based machine learning system supports the analysis of regression testing results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.01367v1.pdf"}
{"id": "1505.01451", "abstract": "  An analytic model of the heliosheath (HS) between the termination shock (TS) and the heliopause (HP) is developed in the limit in which the interstellar flow and magnetic field are neglected. The heliosphere in this limit is axisymmetric and the overall structure of the HS and HP are controlled by the solar magnetic field even in the limit in which the ratio of the plasma to magnetic field pressure, β=8π P/B^2, in the HS is large. The tension of the solar magnetic field produces a drop in the total pressure between the TS and the HP. This same pressure drop accelerates the plasma flow downstream of the TS into the North and South directions to form two collimated jets. The radii of these jets are controlled by the flow through the TS and the acceleration of this flow by the magnetic field – a stronger solar magnetic field boosts the velocity of the jets and reduces the radii of the jets and the HP. Magnetohydrodynamic (MHD) simulations of the global helioshere embedded in a stationary interstellar medium match well with the analytic model. The results suggest that mechanisms that reduce the HS plasma pressure downstream of the TS can enhance the jet outflow velocity and reduce the HP radius to values more consistent with the Voyager 1 observations than in current global models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.01451v2.pdf"}
{"id": "1505.01723", "abstract": "  Recent decades have witnessed online social media being a big-data window for quantificationally testifying conventional social theories and exploring much detailed human behavioral patterns. In this paper, by tracing the emoticon use in Weibo, a group of hidden \"ambivalent users\" are disclosed for frequently posting ambivalent tweets containing both positive and negative emotions. Further investigation reveals that this ambivalent expression could be a novel indicator of many unusual social behaviors. For instance, ambivalent users with the female as the majority like to make a sound in midnights or at weekends. They mention their close friends frequently in ambivalent tweets, which attract more replies and thus serve as a more private communication way. Ambivalent users also respond differently to public affairs from others and demonstrate more interests in entertainment and sports events. Moreover, the sentiment shift of words adopted in ambivalent tweets is more evident than usual and exhibits a clear \"negative to positive\" pattern. The above observations, though being promiscuous seemingly, actually point to the self regulation of negative mood in Weibo, which could find its base from the emotion management theories in sociology but makes an interesting extension to the online environment. Finally, as an interesting corollary, ambivalent users are found connected with compulsive buyers and turn out to be perfect targets for online marketing. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.01723v1.pdf"}
{"id": "1505.02670", "abstract": "  We study the fluctuations of the amplitude (i.e. the Higgs-Anderson) mode in a superconducting system of coupled Dirac particles proposed as a model for possible surface or interface superconductivity in rhombohedral graphite. We show that the absence of Fermi energy and vanishing of the excitation gap of the collective amplitude mode in the model leads to a large fluctuation contribution to thermodynamic quantities such as the heat capacity. As a consequence, the mean-field theory becomes inaccurate indicating that the interactions lead to a strongly correlated state. We also present a microscopic derivation of the Ginzburg-Landau theory corresponding to this model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.02670v2.pdf"}
{"id": "1505.04316", "abstract": "  High momentum hadron suppression is considered to be an excellent probe of jet-medium interactions in QCD matter created in ultra-relativistic heavy ion collisions. We previously showed that our dynamical energy loss formalism can accurately explain suppression measurements at 200 GeV Au+Au collisions at RHIC and 2.76 TeV Pb+Pb collisions at the LHC. With the upcoming LHC measurements at notably higher collision energies, there is a question of what differences, with respect to the current (2.76 TeV) measurements, can be expected. In this paper we concentrate on heavy flavor suppression at the upcoming 5.1 TeV Pb+Pb collisions energy at the LHC. Naively, one would expect a notably (∼ 30%) larger suppression at 5.1 TeV collision energy, due to estimated (significant) energy loss increase when transitioning from 2.76 to 5.1 TeV. Surprisingly, more detailed calculations predict nearly the same suppression results at these two energies. We show that this unexpected result is due to an interplay of the following two effects, which essentially cancel each other: i) flattening of the initial distributions with increasing collision energies, and ii) significantly slower than naively expected increase in the energy loss. Therefore, the obtained nearly the same suppression provides a clear (qualitative and quantitative) test of our energy loss formalism. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.04316v1.pdf"}
{"id": "1505.04378", "abstract": "  We examine conditions for finite-time collapse of the solutions of the higher-order nonlinear Schrödinger (NLS) equation incorporating third-order dispersion, self-steepening, linear and nonlinear gain and loss, and Raman scattering; this is a system that appears in many physical contexts as a more realistic generalization of the integrable NLS. By using energy arguments, it is found that the collapse dynamics is chiefly controlled by the linear/nonlinear gain/loss strengths. We identify a critical value of the linear gain, separating the possible decay of solutions to the trivial zero-state, from collapse. The numerical simulations, performed for a wide class of initial data, are found to be in very good agreement with the analytical results, and reveal long-time stability properties of localized solutions. The role of the higher-order effects to the transient dynamics is also revealed in these simulations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.04378v2.pdf"}
{"id": "1505.05113", "abstract": "  Modified gravity models have been constantly proposed with the purpose of evading some standard gravity shortcomings. Recently proposed by A.H. Chamseddine and V. Mukhanov, the Mimetic Gravity arises as an optimistic alternative. Our purpose in this work is to derive Tolman-Oppenheimer-Volkoff equations and solutions for such a gravity theory. We solve them numerically for quark star and neutron star cases. The results are carefully discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.05113v2.pdf"}
{"id": "1505.06958", "abstract": "  We propose to realize an exotic Haldane superfluid (HSF) phase in an extended Bose-Hubbard model on the two-leg ladder (i.e., a two-species mixture of interacting bosons). The proposal is confirmed by means of large-scale quantum Monte Carlo simulations, with a significant part of the ground-state phase diagram being revealed. Most remarkably, the newly discovered HSF phase features both superfluidity and the non-local topological Haldane order. The effects induced by varying the number of legs are furthermore explored. Our results shed light on how topological superfluid emerges in bosonic systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.06958v2.pdf"}
{"id": "1506.03897", "abstract": "  We study static, spherically symmetric mixed configurations with a nontrivial (wormhole) spacetime topology provided by the presence of two interacting ghost scalar fields. Wormhole is assumed to be filled by a perfect relativistic neutron fluid modeled by a polytropic equation of state. For such mixed configurations, we find regular, asymptotically flat general relativistic solutions. It is shown that the maximum of the fluid density is always shifted from the center, and the resulting configurations represent, in general, double-throat systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1506/1506.03897v2.pdf"}
{"id": "1506.04751", "abstract": "  We report Markov chain Monte Carlo fits of the thermophysical model of Wright (2007) to the fluxes of 10 asteroids which have been observed by both WISE and NEOWISE. This model is especially useful when one has observations of an asteroid at multiple epochs, as it takes advantage of the views of different local times and latitudes to determine the spin axis and the thermal parameter. Many of the asteroids NEOWISE observes will have already been imaged by WISE, so this proof of concept shows there is an opportunity to use a rotating cratered thermophysical model to determine surface thermal properties of a large number of asteroids. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1506/1506.04751v2.pdf"}
{"id": "1506.05052", "abstract": "  The majority of solid tumours arise in epithelia and therefore much research effort has gone into investigating the growth, renewal and regulation of these tissues. Here we review different mathematical and computational approaches that have been used to model epithelia. We compare different models and describe future challenges that need to be overcome in order to fully exploit new data which present, for the first time, the real possibility for detailed model validation and comparison. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1506/1506.05052v1.pdf"}
{"id": "1507.03929", "abstract": "  We construct a relationship between integral and differential representation of second-order Jordan chains. Conditions to obtain regular potentials through the confluent supersymmetry algorithm when working with the differential representation are obtained using this relationship. Furthermore, it is used to find normalization constants of wave functions of quantum systems that feature energy-dependent potentials. Additionally, this relationship is used to express certain integrals involving functions that are solution of Schrodinger equations through derivatives. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.03929v1.pdf"}
{"id": "1507.04031", "abstract": "  An angular effective mass formalism previously introduced is used to study the density of states in warped and non-warped energy bands. Band warping may or may not increase the density-of-states effective mass. Band \"corrugation,\" referring to energy dispersions that deviate \"more severely\" from being twice-differentiable at isolated critical points, may also vary independently of density-of-states effective masses and band warping parameters. We demonstrate these effects and the superiority of an angular effective mass treatment for valence band energy dispersions in cubic materials. We also provide some two-dimensional physical and mathematical examples that may be relevant to studies of band warping in heterostructures and surfaces. These examples may also be useful in clarifying the interplay between possible band warping and band non-parabolicity for non-degenerate conduction band minima in thermoelectric materials of corresponding interest. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.04031v1.pdf"}
{"id": "1507.05026", "abstract": "  We compute the renormalized expectation value of the square of a massless, conformally coupled, quantum scalar field on the brane of a higher-dimensional black hole. Working in the AADD brane-world scenario, the extra dimensions are flat and we assume that the compactification radius is large compared with the size of the black hole. The four-dimensional on-brane metric corresponds to a slice through a higher-dimensional Schwarzschild-Tangherlini black hole geometry and depends on the number of bulk space-time dimensions. The quantum scalar field is in a thermal state at the Hawking temperature. An exact, closed-form expression is derived for the renormalized expectation value of the square of the quantum scalar field on the event horizon of the black hole. Outside the event horizon, this renormalized expectation value is computed numerically. The answer depends on the number of bulk space-time dimensions, with a magnitude which increases rapidly as the number of bulk space-time dimensions increases. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.05026v2.pdf"}
{"id": "1507.06051", "abstract": "  Planets are known to orbit giant stars, yet there is a shortage of planets orbiting within  0.5 AU (P<100 days). First-ascent giants have not expanded enough to engulf such planets, but tidal forces can bring planets to the surface of the star far beyond the stellar radius. So the question remains: are tidal forces strong enough in these stars to engulf all the missing planets? We describe a high-cadence observational program to obtain precise radial velocities of bright giants from Weihai Observatory of Shandong University. We present data on the planet host Beta Gem (HD 62509), confirming our ability to derive accurate and precise velocities; our data achieve an rms of 7.3 m/s about the Keplerian orbit fit. This planet-search programme currently receives  100 nights per year, allowing us to aggressively pursue short-period planets to determine whether they are truly absent. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.06051v1.pdf"}
{"id": "1507.08614", "abstract": "  We perform a joint analysis of current data from cosmology and laboratory experiments to constrain the neutrino mass parameters in the framework of bayesian statistics, also accounting for uncertainties in nuclear modeling, relevant for neutrinoless double β decay (0ν2β) searches. We find that a combination of current oscillation, cosmological and 0ν2β data constrains m_ββ < 0.045 eV (0.014  eV < m_ββ < 0.066  eV) at 95% C.L. for normal (inverted) hierarchy. This result is in practice dominated by the cosmological and oscillation data, so it is not affected by uncertainties related to the interpretation of 0ν2β data, like nuclear modeling, or the exact particle physics mechanism underlying the process. We then perform forecasts for forthcoming and next-generation experiments, and find that in the case of normal hierarchy, given a total mass of 0.1 eV, and assuming a factor-of-two uncertainty in the modeling of the relevant nuclear matrix elements, it will be possible to measure the total mass itself, the effective Majorana mass and the effective electron mass with an accuracy (at 95% C.L.) of 0.05, 0.015, 0.02 eV respectively, as well as to be sensitive to one of the Majorana phases. This assumes that neutrinos are Majorana particles and that the mass mechanism gives the dominant contribution to 0ν2β decay. We argue that more precise nuclear modeling will be crucial to improve these sensitivities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.08614v2.pdf"}
{"id": "1507.08794", "abstract": "  We consider the conformal blocks in the theories with extended conformal W-symmetry for the integer Virasoro central charges. We show that these blocks for the generalized twist fields on sphere can be computed exactly in terms of the free field theory on the covering Riemann surface, even for a non-abelian monodromy group. The generalized twist fields are identified with particular primary fields of the W-algebra, and we propose a straightforward way to compute their W-charges. We demonstrate how these exact conformal blocks can be effectively computed using the technique arisen from the gauge theory/CFT correspondence. We discuss also their direct relation with the isomonodromic tau-function for the quasipermutation monodromy data, which can be an encouraging step on the way of definition of generic conformal blocks for W-algebra using the isomonodromy/CFT correspondence. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.08794v2.pdf"}
{"id": "1508.00368", "abstract": "  We explore the challenges posed by the violation of Bell-like inequalities by d-dimensional systems exposed to imperfect state-preparation and measurement settings. We address, in particular, the limit of high-dimensional systems, naturally arising when exploring the quantum-to-classical transition. We show that, although suitable Bell inequalities can be violated, in principle, for any dimension of given subsystems, it is in practice increasingly challenging to detect such violations, even if the system is prepared in a maximally entangled state. We characterize the effects of random perturbations on the state or on the measurement settings, also quantifying the efforts needed to certify the possible violations in case of complete ignorance on the system state at hand. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.00368v2.pdf"}
{"id": "1508.01134", "abstract": "  We examine selected aspects of peer review and suggest possible improvements. To this end, we analyse a dataset containing information about 300 papers submitted to the Biochemistry and Biotechnology section of the Journal of the Serbian Chemical Society. After separating the peer review process into stages that each review has to go through, we use a weighted directed graph to describe it in a probabilistic manner and test the impact of some modifications of the editorial policy on the efficiency of the whole process. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.01134v1.pdf"}
{"id": "1508.04294", "abstract": "  Social networks constitute a new platform for information propagation, but its success is crucially dependent on the choice of spreaders who initiate the spreading of information. In this paper, we remove edges in a network at random and the network segments into isolated clusters. The most important nodes in each cluster then form a group of influential spreaders, such that news propagating from them would lead to an extensive coverage and minimal redundancy. The method well utilizes the similarities between the pre-percolated state and the coverage of information propagation in each social cluster to obtain a set of distributed and coordinated spreaders. Our tests on the Facebook networks show that this method outperforms conventional methods based on centrality. The suggested way of identifying influential spreaders thus sheds light on a new paradigm of information propagation on social networks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.04294v1.pdf"}
{"id": "1508.04388", "abstract": "  The quest for a quantitative characterization of community and modular structure of complex networks produced a variety of methods and algorithms to classify different networks. However, it is not clear if such methods provide consistent, robust and meaningful results when considering hierarchies as a whole. Part of the problem is the lack of a similarity measure for the comparison of hierarchical community structures. In this work we give a contribution by introducing the hierarchical mutual information, which is a generalization of the traditional mutual information, and allows to compare hierarchical partitions and hierarchical community structures. The normalized version of the hierarchical mutual information should behave analogously to the traditional normalized mutual information. Here, the correct behavior of the hierarchical mutual information is corroborated on an extensive battery of numerical experiments. The experiments are performed on artificial hierarchies, and on the hierarchical community structure of artificial and empirical networks. Furthermore, the experiments illustrate some of the practical applications of the hierarchical mutual information. Namely, the comparison of different community detection methods, and the study of the consistency, robustness and temporal evolution of the hierarchical modular structure of networks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.04388v2.pdf"}
{"id": "1508.04889", "abstract": "  Theoretical approaches to strong field phenomena driven by plasmonic fields are based on the length gauge formulation of the laser-matter coupling. From the theoretical viewpoint it is known there exists no preferable gauge and consequently the predictions and outcomes should be independent of this choice. The use of the length gauge is mainly due to the fact that the quantity obtained from finite elements simulations of plasmonic fields is the plasmonic enhanced laser electric field rather than the laser vector potential. In this paper we develop, from first principles, the velocity gauge formulation of the problem and we apply it to the high-order harmonic generation (HHG) in atoms. A comparison to the results obtained with the length gauge is made. It is analytically and numerically demonstrated that both gauges give equivalent descriptions of the emitted HHG spectra resulting from the interaction of a spatially inhomogeneous field and the single active electron (SAE) model of the helium atom. We discuss, however, advantages and disadvantages of using different gauges in terms of numerical efficiency. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.04889v1.pdf"}
{"id": "1508.06958", "abstract": "  Gaussian mixture models are central to classical statistics, widely used in the information sciences, and have a rich mathematical structure. We examine their maximum likelihood estimates through the lens of algebraic statistics. The MLE is not an algebraic function of the data, so there is no notion of ML degree for these models. The critical points of the likelihood function are transcendental, and there is no bound on their number, even for mixtures of two univariate Gaussians. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.06958v2.pdf"}
{"id": "1508.07729", "abstract": "  The aim of this paper is to discuss in some detail the two different quantum schemes for duopoly problems. We investigate under what conditions one of the schemes is more reasonable that the other one. Using the Cournot's duopoly example we show that the current quantum schemes require a slight refinement so that they output the classical game in a particular case. Then we show how the amendment changes the way of studying the quantum games with respect to Nash equilibria. Finally, we define another scheme for the Cournot's duopoly in terms of quantum computation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.07729v1.pdf"}
{"id": "1509.05023", "abstract": "  New-generation X-ray polarimeters currently under development promise to open a new window in the study of high-energy astrophysical sources. Among them, neutron stars appear particularly suited for polarization measurements. Radiation from the (cooling) surface of a neutron star is expected to exhibit a large intrinsic polarization degree due to the star strong magnetic field (≈ 10^12-10^15 G), which influences the plasma opacity in the outermost stellar layers. The polarization fraction and polarization angle as measured by an instrument, however, do not necessary coincide with the intrinsic ones derived from models of surface emission. This is due to the effects of quantum electrodynamics in the highly magnetized vacuum around the star (the vacuum polarization) coupled with the rotation of the Stokes parameters in the plane perpendicular to the line of sight induced by the non-uniform magnetic field. Here we revisit the problem and present an efficient method for computing the observed polarization fraction and polarization angle in the case of radiation coming from the entire surface of a neutron star, accounting for both vacuum polarization and geometrical effects due to the extended emitting region. Our approach is fairly general and is illustrated in the case of blackbody emission from a neutron star with either a dipolar or a (globally) twisted magnetic field. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.05023v1.pdf"}
{"id": "1509.06826", "abstract": "  We translate the quantum teleportation protocol into a sequence of coherent operations involving three degrees of freedom of a classical laser beam. The protocol, which we demonstrate experimentally, transfers the polarisation state of the input beam to the transverse mode of the output beam. The role of quantum entanglement is played by a non-separable mode describing the path and transverse degrees of freedom. Our protocol illustrates the possibility of new optical applications based on this intriguing classical analogue of quantum entanglement. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.06826v3.pdf"}
{"id": "1509.09081", "abstract": "  The theory of dynamical Coulomb blockade is extended to tunneling elements driven by a time-dependent voltage. It is shown that for standard set-ups where an external voltage is applied to a tunnel junction via an impedance, time-dependent driving entails an excitation of the modes of the electromagnetic environment by the applied voltage. Previous approaches for ac driven circuits need to be extended to account for the driven bath modes. A unitary transformation involving also the variables of the electromagnetic environment is introduced which allows to split-off the time-dependence from the Hamiltonian in the absence of tunneling. This greatly simplifies perturbation-theoretical calculations based on treating the tunneling Hamiltonian as a perturbation. In particular, the average current flowing in the leads of the tunnel junction is studied. Explicit results are given for the case of an applied voltage with a constant dc part and a sinusoidal ac part. The connection with standard dynamical Coulomb blockade theory for constant applied voltage is established. It is shown that an alternating voltage source reveals significant additional effects caused by the electromagnetic environment. The hallmark of dynamical Coulomb blockade in ac driven devices is a suppression of higher harmonics of the current by the electromagnetic environment. The theory presented basically applies to all tunneling devices driven by alternating voltages. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.09081v2.pdf"}
{"id": "1510.00647", "abstract": "  We validate the application of our recent orbital-free density functional theory (DFT) approach, [Phys. Rev. Lett. 113, 155006 (2014)], for the calculation of ionic and electronic transport properties of dense plasmas. To this end, we calculate the self-diffusion coefficient, the viscosity coefficient, the electrical and thermal conductivities, and the reflectivity coefficient of hydrogen and aluminum plasmas. Very good agreement is found with orbital-based Kohn-Sham DFT calculations at lower temperatures. Because the method does not scale with temperature, we can produce results at much higher temperatures than is accessible by the Kohn-Sham method. Our results for warm dense aluminum at solid density are inconsistent with the recent experimental results reported by Sperling et al. [Phys. Rev. Lett. 115, 115001 (2015)]. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.00647v1.pdf"}
{"id": "1511.00094", "abstract": "  Hyperentanglement, the entanglement in several degrees of freedom (DOFs) of a quantum system, has attracted much attention as it can be used to increase both the channel capacity of quantum communication and its security largely. Here, we present the first scheme to completely distinguish the hyperentangled Bell states of two-photon systems in three DOFs with the help of cross-Kerr nonlinearity without destruction, including two longitudinal momentum DOFs and the polarization DOF. We use cross-Kerr nonlinearity to construct quantum nondemolition detectors which can be used to make a parity-check measurement and analyze Bell states of two-photon systems in different DOFs. Our complete scheme for two-photon six-qubit hyperentangled Bell-state analysis may be useful for the practical applications in quantum information, especially in long-distance high-capacity quantum communication. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.00094v2.pdf"}
{"id": "1511.00629", "abstract": "  Photoelectron spectra and photoelectron angular distributions obtained in photoionization reveal important information on e.g. charge transfer or hole coherence in the parent ion. Here we show that optimal control of the underlying quantum dynamics can be used to enhance desired features in the photoelectron spectra and angular distributions. To this end, we combine Krotov's method for optimal control theory with the time-dependent configuration interaction singles formalism and a splitting approach to calculate photoelectron spectra and angular distributions. The optimization target can account for specific desired properties in the photoelectron angular distribution alone, in the photoelectron spectrum, or in both. We demonstrate the method for hydrogen and then apply it to argon under strong XUV radiation, maximizing the difference of emission into the upper and lower hemispheres, in order to realize directed electron emission in the XUV regime. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.00629v1.pdf"}
{"id": "1511.02024", "abstract": "  In a recent paper, Levy and Goldberg pointed out an interesting connection between prediction-based word embedding models and count models based on pointwise mutual information. Under certain conditions, they showed that both models end up optimizing equivalent objective functions. This paper explores this connection in more detail and lays out the factors leading to differences between these models. We find that the most relevant differences from an optimization perspective are (i) predict models work in a low dimensional space where embedding vectors can interact heavily; (ii) since predict models have fewer parameters, they are less prone to overfitting.   Motivated by the insight of our analysis, we show how count models can be regularized in a principled manner and provide closed-form solutions for L1 and L2 regularization. Finally, we propose a new embedding model with a convex objective and the additional benefit of being intelligible. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.02024v1.pdf"}
{"id": "1511.04450", "abstract": "  Motivated by recent progress in electron quantum optics, we revisit the question of single-electron entanglement, specifically whether the state of a single electron in a superposition of two separate spatial modes should be considered entangled. We first discuss a gedanken experiment with single-electron sources and detectors, and demonstrate deterministic (i. e. without post-selection) Bell inequality violation. This implies that the single-electron state is indeed entangled and, furthermore, nonlocal. We then present an experimental scheme where single-electron entanglement can be observed via measurements of the average currents and zero-frequency current cross-correlators in an electronic Hanbury Brown-Twiss interferometer driven by Lorentzian voltage pulses. We show that single-electron entanglement is detectable under realistic operating conditions. Our work settles the question of single-electron entanglement and opens promising perspectives for future experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.04450v2.pdf"}
{"id": "1511.05111", "abstract": "  In this work we study the majority-vote model with the presence of two distinc noises. The first one is the usual noise q, that represents the probability that a given agent follows the minority opinion of his/her social contacts. On the other hand, we consider the independent behavior, such that an agent can choose his/her own opinion +1 or -1 with equal probability, independent of the group's norm. We study the impact of the presence of such two kinds of stochastic driving in the phase transitions of the model, considering the mean field and the square lattice cases. Our results suggest that the model undergoes a nonequilibrium order-disorder phase transition even in the absence of the noise q, due to the independent behavior, but this transition may be suppressed. In addition, for both topologies analyzed, we verified that the transition is in the same universality class of the equilibrium Ising model, i.e., the critical exponents are not affected by the presence of the second noise, associated with independence. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.05111v2.pdf"}
{"id": "1511.05655", "abstract": "  We investigate the Q-ball decay into the axino dark matter in the gauge-mediated supersymmetry breaking. In our scenario, the Q ball decays mainly into nucleons and partially into axinos to account respectively for the baryon asymmetry and the dark matter of the universe. The Q ball decays well before the big bang nucleosynthesis so that it is not affected by the decay. We show the region of the parameters which realizes this scenario. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.05655v1.pdf"}
{"id": "1512.05224", "abstract": "  We investigate phases of spinless fermions on the honeycomb lattice with nearest neighbor interaction in the Hofstadter regime. The interaction induces incompressible nematic and ferri-electric phases with broken translation symmetry. Some of the transitions are accompanied by changes in the Hall conductivity. We study pair correlations and show that the quantum metric, averaged over the Brillouin zone, characterizes the shape of the pair correlation function. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.05224v2.pdf"}
{"id": "1512.05911", "abstract": "  Fundamental sensitivity of an optical interferometric gravitational wave detector increases with increase of the optical power which, in turn, limited because of the opto-mechanical parametric instabilities of the interferometer. We propose to optimize geometrical shape of the mirrors of the detector to reduce the diffraction-limited finesse of unessential optical modes of the interferometer resulting in increase of the threshold of the opto-mechanical instabilities and subsequent increase of the measurement sensitivity. Utilizing parameters of the LIGO interferometer we found that the proposed technique allows constructing a Fabry-Perot interferometer with round trip diffraction loss of the fundamental mode not exceeding 5 ppm, whereas the loss of the first dipole as well as the other high order modes exceed 1,000 ppm and 8,000 ppm, respectively. The optimization comes at the price of tighter tolerances on the mirror tilt stability, but does not result in a significant modification of the optical beam profile and does not require changes in the the gravity detector read-out system. The cavity with proposed mirrors is also stable with respect to the slight modification of the mirror shape. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.05911v1.pdf"}
{"id": "1512.07383", "abstract": "  Typically, in the dynamical theory of extremal events, the function that gauges the intensity of a phenomenon is assumed to be convex and maximal, or singular, at a single, or at most a finite collection of points in phase–space. In this paper we generalize this situation to fractal landscapes, i.e. intensity functions characterized by an uncountable set of singularities, located on a Cantor set. This reveals the dynamical rôle of classical quantities like the Minkowski dimension and content, whose definition we extend to account for singular continuous invariant measures. We also introduce the concept of extremely rare event, quantified by non–standard Minkowski constants and we study its consequences to extreme value statistics. Limit laws are derived from formal calculations and are verified by numerical experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.07383v2.pdf"}
{"id": "1512.08326", "abstract": "  The use of pulsars as astrophysical clocks for gravitational wave experiments demands the highest possible timing precision. Pulse times of arrival (TOAs) are limited by stochastic processes that occur in the pulsar itself, along the line of sight through the interstellar medium, and in the measurement process. On timescales of seconds to hours, the TOA variance exceeds that from template-fitting errors due to additive noise. We assess contributions to the total variance from two additional effects: amplitude and phase jitter intrinsic to single pulses and changes in the interstellar impulse response from scattering. The three effects have different dependencies on time, frequency, and pulse signal-to-noise ratio. We use data on 37 pulsars from the North American Nanohertz Observatory for Gravitational Waves to assess the individual contributions to the overall intraday noise budget for each pulsar. We detect jitter in 22 pulsars and estimate the average value of RMS jitter in our pulsars to be ∼ 1% of pulse phase. We examine how jitter evolves as a function of frequency and find evidence for evolution. Finally, we compare our measurements with previous noise parameter estimates and discuss methods to improve gravitational wave detection pipelines. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.08326v2.pdf"}
{"id": "1601.00847", "abstract": "  Thread-like structures are pervasive across scales, from polymeric proteins to root systems to galaxy filaments, and their characteristics can be readily investigated in the network formalism. Yet, network links usually represent only parts of filaments, which, when neglected, may lead to erroneous conclusions from network-based analyses. The existing alternatives to detect filaments in network representations require tuning of parameters over a large range of values and treat all filaments equally, thus, precluding automated analysis of diverse filamentous systems. Here, we propose a fully automated and robust optimisation-based approach to detect filaments of consistent intensities and angles in a given network. We test and demonstrate the accuracy of our solution with contrived, biological, and cosmic filamentous structures. In particular, we show that the proposed approach provides powerful automated means to study properties of individual actin filaments in their network context. Our solution is made publicly available as an open-source tool, DeFiNe, facilitating decomposition of any given network into individual filaments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.00847v1.pdf"}
{"id": "1601.01635", "abstract": "  The concepts of fuzzy objects and their classes are described that make it possible to structurally represent knowledge about fuzzy and partially-defined objects and their classes. Operations over such objects and classes are also proposed that make it possible to obtain sets and new classes of fuzzy objects and also to model variations in object structures under the influence of external factors. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.01635v2.pdf"}
{"id": "1601.02680", "abstract": "  The Brazilian government often misclassifies the goods it buys. That makes it hard to audit government expenditures. We cannot know whether the price paid for a ballpoint pen (code #7510) was reasonable if the pen was misclassified as a technical drawing pen (code #6675) or as any other good. This paper shows how we can use machine learning to reduce misclassification. I trained a support vector machine (SVM) classifier that takes a product description as input and returns the most likely category codes as output. I trained the classifier using 20 million goods purchased by the Brazilian government between 1999-04-01 and 2015-04-02. In 83.3", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.02680v1.pdf"}
{"id": "1602.01360", "abstract": "  We revisit model calculations of the anomalous Hall effect (AHE) and show that, in isotropic Rashba-coupled two-dimensional electron gas (2DEG) with pointlike potential impurities, the full solution of the semiclassical Boltzmann equation (SBE) may differ from the widely-used 1/τ^||     1/τ^⊥ solution [Phys. Rev. B 68, 165311 (2003)]. Our approach to AHE is analogous to the SBE-based analysis of the anisotropic magnetoresistance leading to an integral equation for the distribution function [Phys. Rev. B 79, 045427 (2009)] but in the present case, we reduce the description to band-index-dependent transport relaxation times. When both Rashba bands are partially occupied, these are determined by solving a system of linear equations. Detailed calculations show that, for intrinsic and hybrid skew scatterings the difference between 1/τ^||     1/τ^⊥ and the full solution of SBE is notable for large Fermi energies. For coordinate-shift effects, the side-jump velocity acquired in the inter-band elastic scattering process is shown to be more important for larger Rashba coupling and may even exceed the intra-band one for the outer Rashba band. The coordinate-shift contribution to AHE in the considered case notably differs from that in the limit of smooth disorder potential analyzed before. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.01360v3.pdf"}
{"id": "1602.04137", "abstract": "  We study the Neo-Riemannian principle of parsimonious voice-leading using tools and techniques from classical graph theory and the modern field of complex networks. We quantify the relative importance of particular chords within this framework. The graph-theoretic notion of eccentricity suggests that when working in a harmonic scheme dictated by any common musical scale, no triad is any more isolated than any other. Complex network theory refines this idea, and in this context provides measures of how important particular triads might be for the flow of chord progressions through the harmonic network. We review and compare several different such measures of centrality and communicability. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.04137v1.pdf"}
{"id": "1602.06152", "abstract": "  Quantum communication demands efficient distribution of quantum entanglement across a network of connected partners. The search for efficient strategies for the entanglement distribution may be based on percolation theory, which describes evolution of network connectivity with respect to some network parameters. In this framework, the probability to establish perfect entanglement between two remote partners decays exponentially with the distance between them before the percolation transition point, which unambiguously defines percolation properties of any classical network or lattice. Here we introduce quantum networks created with local operations and classical communication, which exhibit non-classical percolation transition points leading to the striking communication advantages over those offered by the corresponding classical networks. We show, in particular, how to establish perfect entanglement between any two nodes in the simplest possible network – the 1D chain – using imperfect entangled pairs of qubits. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.06152v2.pdf"}
{"id": "1602.07429", "abstract": "  We have proposed optical tunable CNOT (XOR) and XNOR logic gates using two-dimensional photonic crystal (2DPhC) cavities. Where, air rods with square lattice array have been embedded in Ag-Polymer substrate with refractive index of 1.59. In this work, we have enhanced speed of logic gates by applying two input signals with a phase difference at the same wavelength for 2DPhC cavities. Where, we have adjusted the phases of input and control signals equal with π/3 and zero, respectively. The response time of the structure and quality factor of the cavities are in the range of femtosecond and 2000, respectively. Then, we have used electro-optic property of the substrate material to change the cavities resonance wavelengths. By this means, we could design the logic gates and demonstrate a tunable range of 23nm for their operation wavelength. The quality factor and the response times of cavities remain constant in the tunable range of wavelength, approximately. The evaluated least ON to OFF logic-level contrast ratios for the XOR and XNOR logic gates are 25.45dB and 22.61dB, respectively. The bit rates of the proposed logic gates can reach up to higher than 0.166 P(Peta)bps values. According to the high rapid response time with acceptable quality factor of the PhC cavities, the proposed optical logic gates can be considered as appropriate candidates to be building blocks for applications such as optical integrated circuits and optical processors with an ultrahigh speed of data flow. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.07429v2.pdf"}
{"id": "1603.02360", "abstract": "  Single-photon avalanche photodiode(SPAD) has been widely used in researching of quantum optics. Afterpulsing effect, which is an intrinsic character of SPAD, affects the system performance in most of the experiments and needs to be carefully handled. For a long time, afterpulsing has been presumed to be determined by the pre-ignition avalanche. We studied the afterpulsing effect of a commercial InGaAs/InP SPAD (APD: Princeton Lightwave PGA-300) and demonstrated that its afterpulsing is non-Markov, which has memory effect of the avalanching history. Theoretical analysis and the experimental results clearly indicate that the embodiment of this memory effect is the afterpulsing probability, which increases as the number of ignition-avalanche pulses increase. The conclusion makes the principle of afterpulsing effect clearer and is instructive to the manufacturing processes and afterpulsing evaluation of high-count-rate SPADs. It can also be regarded as an fundamental premise to handle the afterpulsing signals in many applications, such as quantum communication and quantum random number generator. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.02360v1.pdf"}
{"id": "1603.03898", "abstract": "  Generalized spatial modulation (GSM) uses N antenna elements but fewer radio frequency (RF) chains (R) at the transmitter. Spatial modulation and spatial multiplexing are special cases of GSM with R=1 and R=N, respectively. In GSM, apart from conveying information bits through R modulation symbols, information bits are also conveyed through the indices of the R active transmit antennas. In this paper, we derive lower and upper bounds on the the capacity of a (N,M,R)-GSM MIMO system, where M is the number of receive antennas. Further, we propose a computationally efficient GSM encoding (i.e., bits-to-signal mapping) method and a message passing based low-complexity detection algorithm suited for large-scale GSM-MIMO systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.03898v1.pdf"}
{"id": "1603.07258", "abstract": "  We study the coherent dynamics of a two-level parabolic model and ways to enhance population transfer and even to obtain complete population inversion in such models. Motivated by the complete population inversion effect of zero-area pulses found in [1], we consider a scheme where a given coupling function is transformed to a zero-area coupling by performing phase-jump in the middle of the evolution. We also derive a universal formula for the effect of the phase-jump. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.07258v1.pdf"}
{"id": "1603.09703", "abstract": "  Deviations of the observed cosmic microwave background (CMB) from the standard model, known as \"anomalies\", are obviously highly significant and deserve to be pursued more aggressively in order to discover the physical phenomena underlying them. Through intensive investigation we have discovered that there are equally surprising features in the digits of the number π, and moreover there is a remarkable correspondence between each type of peculiarity in the digits of π and the anomalies in the CMB. Putting aside the unreasonable possibility that these are just the sort of flukes that appear when one looks hard enough, the only conceivable conclusion is that, however the CMB anomalies were created, a similar process imprinted patterns in the digits of π. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.09703v2.pdf"}
{"id": "1604.00670", "abstract": "  The Advanced Telescope for High-Energy Astrophysics (Athena) has been selected by ESA as its second large-class mission. The future European X-ray observatory will study the hot and energetic Universe with its launch foreseen in 2028. Microcalorimeters based on superconducting Transition-edge sensor (TES) are the chosen technology for the detectors array of the X-ray Integral Field Unit (X-IFU) on board of Athena. The X-IFU is a 2-D imaging integral-field spectrometer operating in the soft X-ray band (0.3 -12 keV). The detector consists of an array of 3840 TESs coupled to X-ray absorbers and read out in the MHz bandwidth using Frequency Domain Multiplexing (FDM) based on Superconducting QUantum Interference Devices (SQUIDs). The proposed design calls for devices with a high filling-factor, high quantum efficiency, relatively high count-rate capability and an energy resolution of 2.5 eV at 5.9 keV. The paper will review the basic principle and the physics of the TES-based microcalorimeters and present the state-of-the art of the FDM read-out. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.00670v1.pdf"}
{"id": "1604.01678", "abstract": "  Criticality in models of correlated electrons emerges in proximity of a low-temperature singularity in a two-particle Green function. Such singularities are generally related to a symmetry breaking of the one-particle self-energy. A consistent description demands that the symmetry breaking in the self-energy emerges at the critical point of the respective two-particle function. This cannot easily be achieved in models of correlated electrons, since there are two ways connecting one- and two-electron functions that cannot be made fully equivalent in approximations. We present a general construction of diagrammatic two-particle approximations consistent with the one-particle functions so that both produce qualitatively the same quantum critical behavior in thermodynamically equivalent descriptions. The general scheme is applied on the single-impurity Anderson model to derive qualitatively the same Kondo critical scale from the spectral function and the magnetic susceptibility. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.01678v2.pdf"}
{"id": "1604.03717", "abstract": "  We develop a real space renormalisation group analysis of disordered models of glasses, in particular of the spin models at the origin of the Random First Order Transition theory. We find three fixed points respectively associated to the liquid state, to the critical behavior and to the glass state. The latter two are zero-temperature ones; this provides a natural explanation of the growth of effective activation energy scale and the concomitant huge increase of relaxation time approaching the glass transition. The lower critical dimension depends on the nature of the interacting degrees of freedom and is higher than three for all models. This does not prevent three dimensional systems from being glassy. Indeed, we find that their renormalisation group flow is affected by the fixed points existing in higher dimension and in consequence is non-trivial. Within our theoretical framework the glass transition results to be an avoided phase transition. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.03717v1.pdf"}
{"id": "1604.05022", "abstract": "  In this work we introduce the concept of quantum geo-encryption - a protocol that invokes direct quantum encryption of messages coupled to quantum location monitoring of the intended receiver. By obfuscating the quantum information required by both the decrypting process and the location verification process, a communication channel is created in which the encrypted data can only be decrypted at a specific geographic locale. Classical wireless communications can be invoked to unlock the quantum encryption process thereby allowing for any deployment scenario regardless of the channel conditions. Quantum geo-encryption can also be used to realize quantum-computing instructions that can only be implemented at a specific location, and allow for a specified geographical data-route through a distributed network. Here we consider the operational aspects of quantum geo-encryption in generic Rician channels, demonstrating that the likelihood of a successful spoofing attack approaches zero as the adversary moves away from the allowed decrypting location. The work introduced here resolves a long-standing quest to directly deliver information which can only be decrypted at a given location free of assumptions on the physical security of a receiver. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.05022v1.pdf"}
{"id": "1604.05234", "abstract": "  Turbulent flows in the solar wind, large scale current sheets, multiple current sheets, and shock waves lead to the formation of environments in which a dense network of current sheets is established and sustains \"turbulent reconnection\". We constructed a 2D grid on which a number of randomly chosen grid points are acting as scatterers (i.e. magnetic clouds or current sheets). Our goal is to examine how test particles respond inside this large scale collection of scatterers. We study the energy gain of individual particles, the evolution of their energy distribution and their escape time distribution. We have developed a new method to estimate the transport coefficients from the dynamics of the interaction of the particles with the scatterers. Replacing the \"magnetic clouds\" with current sheets, we have proven that the energization processes can be more efficient depending on the strength of the effective electric fields inside the current sheets and their statistical properties. Using the estimated transport coefficients and solving the Fokker-Planck (FP) equation we can recover the energy distribution of the particles only for the sstochastic Fermi process. We have shown that the evolution of the particles inside a turbulent reconnecting volume is not a solution of the FP equation, since the interaction of the particles with the current sheets is \"anomalous\", in contrast to the case of the second order Fermi process. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.05234v4.pdf"}
{"id": "1604.05916", "abstract": "  We study low temperature properties of the Hubbard model for the bismuth nickelate, where degenerate orbitals in the nickel ions and a single orbital in the bismuth ions are taken into account, combining dynamical mean-field theory with the continuous-time quantum Monte Carlo method. We discuss the effect of the attractive interactions to mimic the valence skipping phenomenon in the bismuth ions. We demonstrate how the charge and magnetically ordered states are stable against thermal fluctuations. It is furthermore clarified that the ferromagnetically ordered and orbital ordered states are stabilized due to the presence of the orbital degeneracy at low temperatures. The crossover between metallic and insulating states is also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.05916v1.pdf"}
{"id": "1604.06610", "abstract": "  We analyze the moduli space of non-flat homogeneous affine connections on surfaces. For Type 𝒜 surfaces, we write down complete sets of invariants that determine the local isomorphism type depending on the rank of the Ricci tensor and examine the structure of the associated moduli space. For Type ℬ surfaces which are not Type 𝒜 we show the corresponding moduli space is a simply connected real analytic 4-dimensional manifold with second Betti number equal to 1. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.06610v1.pdf"}
{"id": "1605.01908", "abstract": "  The microscopic mechanism governing the zero-resistance flow of current in some iron-based, high-temperature superconducting materials is not well understood up to now. A central issue concerning the investigation of these materials is their superconducting gap symmetry and structure. Here we present a combined study of low-temperature specific heat and scanning tunnelling microscopy measurements on single crystalline FeSe. The results reveal the existence of at least two superconducting gaps which can be represented by a phenomenological two-band model. The analysis of the specific heat suggests significant anisotropy in the gap magnitude with deep gap minima. The tunneling spectra display an overall \"U\"-shaped gap close to the Fermi level away as well as on top of twin boundaries. These results are compatible with the anisotropic nodeless models describing superconductivity in FeSe. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.01908v2.pdf"}
{"id": "1605.02736", "abstract": "  Using a sample of 98 galaxy clusters recently imaged in the near infra-red with the ESO NTT, WIYN and WHT telescopes, supplemented with 33 clusters from the ESO archive, we measure how the stellar mass of the most massive galaxies in the universe, namely Brightest Cluster Galaxies (BCG), increases with time. Most of the BCGs in this new sample lie in the redshift range 0.2<z<0.6, which has been noted in recent works to mark an epoch over which the growth in the stellar mass of BCGs stalls. From this sample of 132 clusters, we create a subsample of 102 systems that includes only those clusters that have estimates of the cluster mass. We combine the BCGs in this subsample with BCGs from the literature, and find that the growth in stellar mass of BCGs from 10 billion years ago to the present epoch is broadly consistent with recent semi-analytic and semi-empirical models. As in other recent studies, tentative evidence indicates that the stellar mass growth rate of BCGs may be slowing in the past 3.5 billion years. Further work in collecting larger samples, and in better comparing observations with theory using mock images is required if a more detailed comparison between the models and the data is to be made. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.02736v2.pdf"}
{"id": "1605.07318", "abstract": "  Tissue remodelling in diverse developmental contexts require cell shape changes that have been associated with pulsation and flow of the actomyosin cytoskeleton. Here we describe the dynamics of the actomyosin cytoskeleton as a confined active elastomer embedded in the cytosol and subject to turnover of its components. Under affine deformations (homogeneous deformation over a spatially coarse-grained scale), the active elastomer exhibits spontaneous oscillations, propagating waves, contractile collapse and spatiotemporal chaos. The collective nonlinear dynamics shows nucleation, growth and coalescence of actomyosin-dense regions which, beyond a threshold, spontaneously move as a spatially localized traveling front towards one of the boundaries. However, large myosin-induced contractile stresses, can lead to nonaffine deformations due to actin turnover. This results in a transient actin network, that naturally accommodates intranetwork flows of the actomyosin dense regions as a consequence of filament unbinding and rebinding. Our work suggests that the driving force for the spontaneous movement comes from the actomyosin-dense region itself and not the cell boundary. We verify the many predictions of our study in Drosophila embryonic epithelial cells undergoing neighbour exchange during a collective process of tissue extension called germband extension. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.07318v1.pdf"}
{"id": "1605.07898", "abstract": "  We report optical second-harmonic generation (SHG) in reflection from GaSe crystals of 1 to more than 100 layers using a fundamental picosecond pulsed pump at 1.58 eV and a supercontinuum white light pulsed laser with energies ranging from 0.85 to 1.4 eV. The measured reflected SHG signal is maximal in samples of ∼20 layers, decreasing in thicker samples as a result of interference. The thickness- and frequency-dependence of the SHG response of samples thicker than ∼7 layers can be reproduced by a second-order optical susceptibility that is the same as in bulk samples. For samples ≲7 layers, the second-order optical susceptibility is reduced compared to that in thicker samples, which is attributed to the expected bandgap increase in mono- and few-layer GaSe. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.07898v3.pdf"}
{"id": "1605.08105", "abstract": "  We define knowledge as facts, information, and skills acquired by a person through experience or education. In turn, Disciplinary Knowledge is the knowledge related to a specific field or discipline, such as physics. Accountable Disciplinary Knowledge (ADK) is \"what counts\" as important to a community or discipline: the kinds of activities that participants engage in, the problems they value and solve, and methods for solving those problems. Because ADK is determined on a community basis, the details of \"what counts\" will vary with the norms and expectations of the community. In this paper, we use the ADK framework to investigate \"what counts\" as solving problems well in a high school physics classroom from the perspective of the students. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.08105v1.pdf"}
{"id": "1605.08893", "abstract": "  In this article we report about linear and nonlinear optical properties of intersubband cavity polariton samples, where the resonant photonic mode is a defect state in a metallo-dielectric photonic crystal slab. By tuning a single geometric parameter of the resonator, the cavity Q-factor can reach values as large as 85, with a consequent large cooperativity for the light-matter interaction. We show that a device featuring large cooperativity leads to sharp saturation, or even bistability, of the polariton states. This nonlinear dynamics occurs at the crossover between the weak and the strong coupling regimes, where the weak critical coupling concept plays a fundamental role. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.08893v1.pdf"}
{"id": "1606.02578", "abstract": "  This paper is devoted to prove that if an Alexandrov space of curvature not less than κ with a codimension one extremal subset which admits an isometric involution with respect to the induced length metric, then the metric space obtained by gluing the extremal subset along the isometry is an Alexandrov space of curvature not less than κ. This is a generalization of Perelman's doubling and Petrunin's gluing theorems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.02578v1.pdf"}
{"id": "1606.06300", "abstract": "  Josephson junctions are the most prominent nondissipative and at the same time nonlinear elements in superconducting circuits allowing Cooper pairs to tunnel coherently between two superconductors separated by a tunneling barrier. Due to this, physical systems involving Josephson junctions show highly complex behavior and interesting novel phenomena. Here, we consider an infinite one-dimensional chain of superconducting islands where neighboring islands are coupled by capacitances. We study the effect of Josephson junctions shunting each island to a common ground superconductor. We treat the system in the regime where the Josephson energy exceeds the capacitive coupling between the islands. For the case of two offset charges on two distinct islands, we calculate the interaction energy of these charges mediated by quantum phase slips due to the Josephson nonlinearities. We treat the phase slips in an instanton approximation and map the problem onto a classical partition function of interacting particles. Using the Mayer cluster expansion, we find that the interaction potential of the offset charges decays with an universal inverse-square power law behavior. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.06300v1.pdf"}
{"id": "1607.02938", "abstract": "  We have developed a novel two-layer anti-reflection (AR) coating method for large-diameter infrared (IR) filters made of alumina, for the use at cryogenic temperatures in millimeter wave measurements. Thermally- sprayed mullite and polyimide foam (Skybond Foam) are used as the AR material. An advantage of the Skybond Foam is that the index of refraction is chosen between 1.1 and 1.7 by changing the filling factor. Combination with mullite is suitable for wide-band millimeter wave measurements with sufficient IR cutoff capability. We present the material properties, fabrication of a large-diameter IR filter made of alumina with this AR coating method, and characterizations at cryogenic temperatures. This technology can be applied to a low-temperature receiver system with a large-diameter focal plane for next-generation cosmic microwave background (CMB) polarization measurements, such as POLARBEAR-2 (PB-2). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1607/1607.02938v2.pdf"}
{"id": "1607.06937", "abstract": "  We report the optical spectroscopy of four young radio sources which are observed with the Lijiang 2.4m telescope. The Eddington ratios of these sources are similar with those of narrow-line Seyfert 1 galaxies (NLS1s). Their Fe ii emission is strong while [O iii] strength is weak. These results confirm the NLS1 features of young radio sources, except that the width of broad Hβ of young radio sources is larger than that of NLS1s. We thus suggest that the young radio sources are the high black hole mass counterparts of steep-spectrum radio-loud NLS1s. In addition, the broad Hβ component of 4C 12.50 is the blue wing of the narrow component, but not from the broad line region. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1607/1607.06937v1.pdf"}
{"id": "1607.07537", "abstract": "  In this paper, we look into the issue of intra-cell uplink (UL) pilot orthogonalization and schemes for mitigating the inter-cell pilot contamination with a realistic massive multi-input multi-output (MIMO) orthogonal frequency-division multiplexing (OFDM) system model. First, we show how to align the power-delay profiles (PDP) of different users served by one BS so that the pilots sent within one common OFDM symbol are orthogonal. From the derived aligning rule, we see much more users can be sounded in the same OFDM symbol as their channels are sparse in time. Second, in the case of massive MIMO, we show how PDP alignment can help to alleviate the pilot contamination due to inter-cell interference. We demonstrate that, by utilizing the fact that different paths in time are associated with different angles of arrival (AoA), the pilot contamination can be significantly reduced through aligning the PDPs of the users served by different BSs appropriately. Computer simulations further convince us PDP aligning can serve as the new baseline design philosophy for the UL pilots in massive MIMO. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1607/1607.07537v1.pdf"}
{"id": "1608.00030", "abstract": "  Quantum dynamics of magnetic order in a chiral multiferroic chain is studied. We consider two different scenarios: Ultrashort terahertz (THz) excitations or a sudden electric field quench. Performing analytical and numerical exact diagonalization calculations we trace the pulse induced spin dynamics and extract quantities that are relevant to quantum information processing. In particular, we analyze the dynamics of the system chirality, the von Neumann entropy, the pairwise and the many body entanglement. If the characteristic frequencies of the generated states are non-commensurate then a partial loss of pair concurrence occurs. Increasing the system size this effect becomes even more pronounced. Many particle entanglement and chirality are robust and persist in the incommensurate phase. To analyze the dynamical quantum transitions for the quenched and pulsed dynamics we combined the Weierstrass factorization technique for entire functions and Lanczos exact diagonalization method. For a small system we obtained analytical results including the rate function of Loschmidt echo. Exact numerical calculations for a system up to 40 spins confirm phase transition. Quench- induced dynamical transitions have been extensively studied recently. Here we show that related dynamical transitions can be achieved and controlled by appropriate electric field pulses. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.00030v1.pdf"}
{"id": "1608.00799", "abstract": "  Quantum phase transitions reflect singular changes taking place in a many-body ground state, however, computing and analyzing large-scale critical wave functions constitutes a formidable challenge. New physical insights into the sub-Ohmic spin-boson model are provided by the coherent state expansion (CSE), which represents the wave function by a linear combination of classically displaced configurations. We find that the distribution of low-energy displacements displays an emergent symmetry in the absence of spontaneous symmetry breaking, while experiencing strong fluctuations of the order parameter near the quantum critical point. Quantum criticality provides two strong fingerprints in critical low-energy modes: an algebraic decay of the average displacement and a constant universal average squeezing amplitude. These observations, confirmed by extensive variational matrix product states (VMPS) simulations and field theory arguments, offer precious clues into the microscopics of critical many-body states in quantum impurity models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.00799v2.pdf"}
{"id": "1608.01119", "abstract": "  We present an effectively global analytical asymptotic galactic dynamo solution for the regular magnetic field of an axisymmetric thin disc in the saturated state. This solution is constructed by combining two well-known types of local galactic dynamo solution, parameterized by the disc radius. Namely, the critical (zero growth) solution obtained by treating the dynamo equation as a perturbed diffusion equation is normalized using a non-linear solution that makes use of the `no-z' approximation and the dynamical α-quenching non-linearity. This overall solution is found to be reasonably accurate when compared with detailed numerical solutions. It is thus potentially useful as a tool for predicting observational signatures of magnetic fields of galaxies. In particular, such solutions could be painted onto galaxies in cosmological simulations to enable the construction of synthetic polarized synchrotron and Faraday rotation measure (RM) datasets. Further, we explore the properties of our numerical solutions, and their dependence on certain parameter values. We illustrate and assess the degree to which numerical solutions based on various levels of approximation, common in the dynamo literature, agree with one another. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.01119v3.pdf"}
{"id": "1608.02945", "abstract": "  We have detected a 12 M_ Jup planet orbiting in or near the habitable zone of a main-sequence A star via the pulsational phase shifts induced by orbital motion. The planet has an orbital period of 840±20 d and an eccentricity of 0.15. All known planets orbiting main-sequence A stars have been found via the transit method or by direct imaging. The absence of astrometric or radial-velocity detections of planets around these hosts makes ours the first discovery using the orbital motion. It is also the first A star known to host a planet within 1σ of the habitable zone. We find evidence for planets in a large fraction of the parameter space where we are able to detect them. This supports the idea that A stars harbor high-mass planets in wide orbits. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.02945v2.pdf"}
{"id": "1608.03160", "abstract": "  A Weyl semimetal wire with an axial magnetization has metallic surface states (Fermi arcs) winding along its perimeter, connecting bulk Weyl cones of opposite topological charge (Berry curvature). We investigate what happens to this \"Weyl solenoid\" if the wire is covered with a superconductor, by determining the dispersion relation of the surface modes propagating along the wire. Coupling to the superconductor breaks up the Fermi arc into a pair of Majorana modes, separated by an energy gap. Upon variation of the coupling strength along the wire there is a gap inversion that traps the Majorana fermions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.03160v3.pdf"}
{"id": "1609.00573", "abstract": "  Circulant preconditioners are commonly used to accelerate the rate of convergence of iterative methods when solving linear systems of equations with a Toeplitz matrix. Block extensions that can be applied when the system has a block Toeplitz matrix with Toeplitz blocks also have been developed. This paper is concerned with preconditioning of linear systems of equations with a symmetric block Toeplitz matrix with symmetric Toeplitz blocks that stem from the discretization of a linear ill-posed problem. The right-hand side of the linear systems represents available data and is assumed to be contaminated by error. These kinds of linear systems arise, e.g., in image deblurring problems. It is important that the preconditioner does not affect the invariant subspace associated with the smallest eigenvalues of the block Toeplitz matrix to avoid severe propagation of the error in the right-hand side. A perturbation result indicates how the dimension of the subspace associated with the smallest eigenvalues should be chosen and allows the determination of a suitable preconditioner when an estimate of the error in the right-hand side is available. This estimate also is used to decide how many iterations to carry out by a minimum residual iterative method. Applications to image restoration are presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.00573v1.pdf"}
{"id": "1609.02055", "abstract": "  We propose a Berry phase effect on the chiral degrees of freedom of a triangular magnetic molecule. The phase is induced by adiabatically varying an external electric field in the plane of the molecule via a spin-electric coupling mechanism present in these frustrated magnetic molecules. The Berry phase effect depends on spin-orbit interaction splitting and on the electric dipole moment. By varying the amplitude of the applied electric field, the Berry phase difference between the two spin states can take any arbitrary value between zero and π, which can be measured as a phase shift between the two chiral states by using spin-echo techniques. Our result can be used to realize an electric field induced geometric phase-shift gate acting on a chiral qubit encoded in the ground state manifold of the triangular magnetic molecule. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.02055v3.pdf"}
{"id": "1609.04915", "abstract": "  Using one archival high dispersion high quality spectrum of HR8844 (A0V) obtained with the echelle spectrograph SOPHIE at Observatoire de Haute Provence, we show that this star is not a superficially normal A0V star as hitherto thought. The model atmosphere and spectrum synthesis modeling of the spectrum of HR8844 reveals large departures of its abundances from the solar composition. We report here on our first determinations of the elemental abundances of 41 elements in the atmosphere of HR8844. Most of the light elements are underabundant whereas the very heavy elements are overabundant in HR8844.This interesting new chemically peculiar star could be a hybrid object between the HgMn stars and the Am stars. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.04915v1.pdf"}
{"id": "1609.06007", "abstract": "  We have recorded three lunar occultations of Aldebaran (AlfTau) at different telescopes and using various band-passes, from the ultraviolet to the far red. The data have been analyzed using both model-dependent and model-independent methods. The derived uniform-disc angular diameter values have been converted to limb-darkened values using model atmosphere relations, and are found in broad agreement among themselves and with previous literature values. The limb-darkened diameter is about 20.3 milliarcseconds on average . However, we have found indications that the photospheric brightness profile of Aldebaran may have not been symmetric, a finding already reported by other authors for this and for similar late-type stars. At the sampling scale of our brightness profile, between one and two milliarcsecond, the uniform and limb-darkened disc models may not be a good description for Aldebaran. The asymmetries appear to differ with wavelength and over the 137 days time span of our measurements. Surface spots appear as a likely explanation for the differences between observations and the models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.06007v1.pdf"}
{"id": "1609.07225", "abstract": "  In this paper, we have constructed Boson star (BS) solutions in four dimensional scalar-Gauss-Bonnet (sGB) theory. In order to have non-trivial effect from Gauss-Bonnet term, we invoked non-minimal coupling between a complex scalar field and the Gauss-Bonnet term with a coupling parameter, α. We show that the scalar field can no longer take arbitrary value at the center of the star. Furthermore, boson-stars in our higher derivative theory turn out to be slightly massive but much more compact than those in the usual Einstein's gravity. Interestingly, we found that for α<-0.4 and α>0.8, binding energy for all possible boson stars is always negative. This implies that these stars are intrinsically stable against the decay by dispersion. We also present the mass-radius and mass-frequency curves for boson-star and compare them with other compact objects in gravity models derived from Gauss-Bonnet term. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.07225v2.pdf"}
{"id": "1610.07920", "abstract": "  We analyse the evolution of cosmological perturbations which leads to the formation of large isolated voids in the Universe. We assume that initial perturbations are spherical and all components of the Universe (radiation, matter and dark energy) are continuous media with perfect fluid energy–momentum tensors, which interact only gravitationally. Equations of the evolution of perturbations for every component in the comoving to cosmological background reference frame are obtained from equations of energy and momentum conservation and Einstein's ones and are integrated numerically. Initial conditions are set at the early stage of evolution in the radiation-dominated epoch, when the scale of perturbation is much larger than the particle horizon. Results show how the profiles of density and velocity of matter and dark energy are formed and how they depend on parameters of dark energy and initial conditions. In particular, it is shown that final matter density and velocity amplitudes change within range ∼4-7% when the value of equation-of-state parameter of dark energy w vary in the range from –0.8 to –1.2, and change within ∼1% only when the value of effective sound speed of dark energy vary over all allowable range of its values. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.07920v2.pdf"}
{"id": "1610.09609", "abstract": "  Vision-based object detection is one of the fundamental functions in numerous traffic scene applications such as self-driving vehicle systems and advance driver assistance systems (ADAS). However, it is also a challenging task due to the diversity of traffic scene and the storage, power and computing source limitations of the platforms for traffic scene applications. This paper presents a generalized Haar filter based deep network which is suitable for the object detection tasks in traffic scene. In this approach, we first decompose a object detection task into several easier local regression tasks. Then, we handle the local regression tasks by using several tiny deep networks which simultaneously output the bounding boxes, categories and confidence scores of detected objects. To reduce the consumption of storage and computing resources, the weights of the deep networks are constrained to the form of generalized Haar filter in training phase. Additionally, we introduce the strategy of sparse windows generation to improve the efficiency of the algorithm. Finally, we perform several experiments to validate the performance of our proposed approach. Experimental results demonstrate that the proposed approach is both efficient and effective in traffic scene compared with the state-of-the-art. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.09609v1.pdf"}
{"id": "1610.09694", "abstract": "  I discuss some of what is known and unknown about the behavior of black hole binary systems in the quiescent accretion state. Quiescence is important for several reasons: 1) the dominance of the companion star in the optical and IR wavelengths allows the binary parameters to be robustly determined - as an example, we argue that the longer proposed distance to the X-ray source GRO J1655-40 is correct; 2) quiescence represents the limiting case of an extremely low accretion rate, in which both accretion and jets can be observed; 3) understanding the evolution and duration of the quiescent state is a key factor in determining the overall demographics of X-rary binaries, which has taken on a new importance in the era of gravitational wave astronomy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.09694v1.pdf"}
{"id": "1612.03463", "abstract": "  We study finite size and temperature XX0 Heisenberg spin chain in weak and strong coupling regimes. By using an elegant connection of the model to integrable combinatorics and probability, we explore and interpret a possible phase structure of the model in asymptotic limit: the limit of large inverse temperature and size. First, partition function and free energy of the model are derived by using techniques and results from random matrix models and nonintersecting Brownian motion. We show that, in the asymptotic limit, partition function of the model, written in terms of matrix integral, is governed by the Tracy-Widom distribution. Second, the exact analytic results for the free energy, which is obtained by the asymptotic analysis of the Tracy-Widom distribution, indicate a completely new and sophisticated phase structure of the model. This phase structure consists of second- and third-order phase transitions. Finally, to shed light on our new results, we provide a possible interpretation of the phase structure in terms of dynamical behavior of magnons in the spin chain. We demonstrate distinct features of the phases with schematic spin configurations which have definite features in each region of the phase diagram. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.03463v2.pdf"}
{"id": "1612.06759", "abstract": "  We demonstrate a unified scenario for neutrino mass, baryon asymmetry, dark matter and inflation. In addition to a fermion triplet for the so-called minimal dark matter, we extend the standard model by three heavy fields including a scalar singlet, a fermion triplet and a fermion singlet/Higgs triplet. The heavy scalar singlet, which is expected to drive an inflation, and the dark matter fermion triplet are odd under an unbroken Z_2^ discrete symmetry, while the other fields are all even. The heavy fermion triplet offers a tree-level type-III seesaw and then mediates a three-body decay of the inflaton into the standard model lepton and Higgs doublets with the dark matter fermion triplet. The heavy fermion singlet/Higgs triplet not only results in a type-I/II seesaw at tree level but also contributes to the inflaton decay at one-loop level. In this scenario, the type-I/II seesaw contains all of the physical CP phases in the lepton sector and hence the CP violation for the non-thermal leptogenesis by the inflaton decay exactly comes from the imaginary part of the neutrino mass matrix. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.06759v1.pdf"}
{"id": "1612.07199", "abstract": "  Two-dimensional materials have unusual phonon structures due to the presence of flexural (out-of-plane) modes. Although molecular dynamics simulations have been extensively used to study heat transport in such materials, conventional formalisms treat the phonon dynamics isotropically. Here, we decompose the microscopic heat current in atomistic simulations into in-plane and out-of-plane components, corresponding to the in-plane and out-of-plane phonon dynamics, respectively. This decomposition allows for direct computation of the corresponding thermal conductivity components in two-dimensional materials. We apply this decomposition to study heat transport in suspended graphene, using both equilibrium and non-equilibrium molecular dynamics simulations. We show that the flexural component is responsible for about two thirds of the total thermal conductivity in unstrained graphene, and the acoustic flexural component is responsible for the logarithmic divergence of the conductivity when a sufficiently large tensile strain is applied. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.07199v2.pdf"}
{"id": "1612.07347", "abstract": "  We investigate the approach of pure SU(2) lattice gauge theory with the Wilson action to its continuum limit using the deconfining phase transition, the gradient flow and the cooling flow to set the scale. For the gradient and cooling scales we explore three different energy observables and two distinct reference values for the flow time. When the aim is to follow scaling towards the continuum limit, one gains at least a factor of 100 in computational efficiency by relying on the gradient instead of the deconfinement scale. Using cooling instead of the gradient flow one gains another factor of at least 34 in computational efficiency on the gradient flow part without any significant loss in the accuracy of scale setting. Concerning our observables, the message is to keep it simple. The Wilson action itself performs as well as or even better than the other two observables explored. Two distinct fitting forms for scaling are compared of which one connects to asymptotic scaling. Differences of the obtained estimates show that systematic errors of length ratios, though only about 1", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.07347v1.pdf"}
{"id": "1612.08058", "abstract": "  Distribution networks – from vasculature to urban transportation systems – are prevalent in both the natural and consumer worlds. These systems are intrinsically physical in composition and are embedded into real space, properties that lead to constraints on their topological organization. In this study, we compare and contrast two types of biological distribution networks: mycelial fungi and the vasculature system on the surface of rodent brains. Both systems are alike in that they must route resources efficiently, but they are also inherently distinct in terms of their growth mechanisms, and in that fungi are not attached to a larger organism and must often function in unregulated and varied environments. We begin by uncovering a common organizational principle – Rentian scaling – that manifests as hierarchical network layout in both physical and topological space. Simulated models of distribution networks optimized for transport in the presence of fluctuations are also shown to exhibit this feature in their embedding, with similar scaling exponents. However, we also find clear differences in how the fungi and vasculature balance tradeoffs in material cost, efficiency, and robustness. While the vasculature appear well optimized for low cost, but relatively high efficiency, the fungi tend to form more expensive but in turn more robust networks. These differences may be driven by the distinct functions that each system must perform, and the different habitats in which they reside. As a whole, this work demonstrates that distribution networks contain a set of common, emergent design features, as well as tailored optimizations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.08058v1.pdf"}
{"id": "1612.08348", "abstract": "  We present the results of spectroscopic redshift measurements for the galaxy clusters from the first all-sky Planck catalogue of the Sunyaev-Zeldovich sources, that have been mostly identified by means of the optical observations performed previously by our team (Planck Collaboration, 2015a). The data on 13 galaxy clusters at redshifts from z= 0.2 to z= 0.8, including the improved identification and redshift measurement for the cluster PSZ1 G141.73+14.22 at z=0.828, are provided. The measurements were done using the data from Russian-Turkish 1.5-m telescope (RTT-150), 2.2-m Calar Alto Observatory telescope, and 6-m SAO RAS telescope (Bolshoy Teleskop Azimutalnyi, BTA). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.08348v1.pdf"}
{"id": "1612.08877", "abstract": "  The main goal for the GAMMA-400 gamma-ray telescope mission is to perform a sensitive search for signatures of dark matter particles in high-energy gamma-ray emission. Measurements will also concern the following scientific goals: detailed study of the Galactic center region, investigation of point and extended gamma-ray sources, studies of the energy spectra of Galactic and extragalactic diffuse emissions. To perform these measurements the GAMMA-400 gamma-ray telescope possesses unique physical characteristics for energy range from  20 MeV to  1000 GeV in comparison with previous and current space and ground-based experiments. The major advantage of the GAMMA-400 instrument is excellent angular and energy resolutions for gamma-rays above 10 GeV. The gamma-ray telescope angular and energy resolutions for the main aperture at 100-GeV gamma rays are  0.01 deg and  1", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.08877v1.pdf"}
{"id": "1701.03282", "abstract": "  We develop a framework for downlink heterogeneous cellular networks with line-of-sight (LoS) and non-line-of-sight (NLoS) transmissions. Using stochastic geometry, we derive tight approximation of achievable downlink rate that enables us to compare the performance between densifying small cells and expanding BS antenna arrays. Interestingly, we find that adding small cells into the network improves the achievable rate much faster than expanding antenna arrays at the macro BS. However, when the small cell density exceeds a critical threshold, the spacial densification will lose its benefits and further impair the network capacity. To this end, we present the optimal small cell density that maximizes the rate as practical deployment guidance. In contrast, expanding macro BS antenna array can always benefit the capacity until an upper bound caused by pilot contamination, and this bound also surpasses the peak rate obtained from deployment of small cells. Furthermore, we find that allocating part of antennas to distributed small cell BSs works better than centralizing all antennas at the macro BS, and the optimal allocation proportion is also given for practical configuration reference. In summary, this work provides a further understanding on how to leverage small cells and massive MIMO in future heterogeneous cellular networks deployment. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.03282v1.pdf"}
{"id": "1701.03667", "abstract": "  Silicene and germanene are key materials for the field of valleytronics. However, interaction with the substrate, which is necessary to support the electronically active medium, becomes a major obstacle. In the present work, we propose a substrate (F-doped WS_2) that avoids detrimental effects and at the same time induces the required valley polarization, so that no further steps are needed for this purpose. The behavior is explained by proximity effects on silicene/germanene, as demonstrated by first-principles calculations. Broken inversion symmetry due to the presence of WS_2 opens a substantial band gap in silicene/germanene. F doping of WS_2 results in spin polarization, which, in conjunction with proximity-enhanced spin orbit coupling, creates sizable spin-valley polarization. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.03667v1.pdf"}
{"id": "1701.06195", "abstract": "  NaSbS2 is a semiconductor that was recently shown to have remarkable efficacy as a solar absorber indicating efficient charge collection even in defected material. We report first principles calculations of properties that show (1) an indirect gap only slightly smaller than the direct gap, which may impede recombination of photoexcited carriers, (2) highly anisotropic electronic and optical properties reflecting a layered crystal structure, (3) a pushed up valence band maximum due to repulsion from the Sb 5s states and (4) cross-gap hybridization between the S p derived valence bands and the Sb 5p states. This latter feature leads to enhanced Born effective charges that can provide local screening and therefore defect tolerance. These features are discussed in relation to the performance of the compound as a semiconductor with efficient charge collection. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.06195v1.pdf"}
{"id": "1701.06894", "abstract": "  Quantum M-theory is formulated using the current algebra technique. The current algebra is based on a Kac-Moody algebra rather than usual finite dimensional Lie algebra. Specifically, I study the E_11 Kac-Moody algebra that was shown recently to contain all the ingredients of M-theory. Both the internal symmetry and the external Lorentz symmetry can be realized inside E_11, so that, by constructing the current algebra of E_11, I obtain both internal gauge theory and gravity theory. The energy-momentum tensor is constructed as the bilinear form of the currents, yielding a system of quantum equations of motion of the currents/fields. Supersymmetry is incorporated in a natural way. The so-called \"field-current identity\" is built in and, for example, the gravitino field is itself a conserved super-current. One unanticipated outcome is that the quantum gravity equation is not identical to the one obtained from the Einstein-Hilbert action. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.06894v2.pdf"}
{"id": "1701.08492", "abstract": "  This paper studies the zero error capacity of the Nearest Neighbor Error (NNE) channels with a multilevel alphabet. In the NNE channels, a transmitted symbol is a d-tuple of elements in {0,1,2,…, n-1 }. It is assumed that only one element error to a nearest neighbor element in a transmitted symbol can occur. The NNE channels can be considered as a special type of limited magnitude error channels, and it is closely related to error models for flash memories. In this paper, we derive a lower bound of the zero error capacity of the NNE channels based on a result of the perfect Lee codes. An upper bound of the zero error capacity of the NNE channels is also derived from a feasible solution of a linear programming problem defined based on the confusion graphs of the NNE channels. As a result, a concise formula of the zero error capacity is obtained using the lower and upper bounds. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.08492v1.pdf"}
{"id": "1701.08904", "abstract": "  The variational cluster approximation is used to study the isotropic triangular-lattice Hubbard model at half filling, taking into account the nearest-neighbor (t_1) and next-nearest-neighbor (t_2) hopping parameters for magnetic frustrations. We determine the ground-state phase diagram of the model. In the strong correlation regime, the 120^∘ Néel and stripe ordered phases appear, and a nonmagnetic insulating phase emerges in between. In the intermediate correlation regime, the nonmagnetic insulating phase expands to a wider parameter region, which goes into a paramagnetic metallic phase in the weak correlation regime. The critical phase boundary of the Mott metal-insulator transition is discussed in terms of the van Hove singularity evident in the calculated density of states and single-particle spectral function. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.08904v1.pdf"}
{"id": "1702.01274", "abstract": "  The controllability of current quantum technologies allows to implement spin-boson models where two-photon couplings are the dominating terms of light-matter interaction. In this case, when the coupling strength becomes comparable with the characteristic frequencies, a spectral collapse can take place, i.e. the discrete system spectrum can collapse into a continuous band. Here, we analyze the thermodynamic limit of the two-photon Dicke model, which describes the interaction of an ensemble of qubits with a single bosonic mode. We find that there exists a parameter regime where two-photon interactions induce a superradiant phase transition, before the spectral collapse occurs. Furthermore, we extend the mean-field analysis by considering second-order quantum fluctuations terms, in order to analyze the low-energy spectrum and compare the critical behavior with the one-photon case. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.01274v2.pdf"}
{"id": "1702.01347", "abstract": "  The aim of this paper is the derivation of an a-posteriori error estimate for a numerical method based on an exponential scheme in time and spectral Galerkin methods in space. We obtain analytically a rigorous bound on the mean square error conditioned to the calculated data, which is numerically computable and uses the given numerical approximation. Thus one can check a-posteriori the error for a given numerical computation without relying on an asymptotic result.   All estimates are only based on the numerical data and the structure of the equation, but they do not use any a-priori information of the solution, which makes the approach applicable to equations where global existence of solutions is not known. For simplicity of presentation, we develop the method here in a relatively simple situation of a stable one-dimensional Allen-Cahn equation with additive forcing. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.01347v3.pdf"}
{"id": "1702.02250", "abstract": "  By using an exact analytical approach to the time evolution of decay we investigate the tunneling decay of ultracold single atoms, to discuss the conditions for deviations of the exponential decay law. We find that R, given by the ratio of the energy of the decaying fragment ℰ_r to its corresponding width Γ_r, is the relevant quantity in this study. When R is less than 0.3 the decay of the atom goes to a good approximation for the first few lifetimes as exp(-Γ_rt/2ħ)t^-3/2. We also find that for values of R ∼ 1, the nonexponential behavior occurs in a post-exponential regime that goes as t^-3 after around a dozen of lifetimes. The above conditions depend on suitable designed potential parameters and suggest that for values R ≲ 1, the experimental verification of nonexponential decay might be possible. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.02250v1.pdf"}
{"id": "1702.04400", "abstract": "  A procedure for the numerical approximation of high-dimensional Hamilton-Jacobi-Bellman (HJB) equations associated to optimal feedback control problems for semilinear parabolic equations is proposed. Its main ingredients are a pseudospectral collocation approximation of the PDE dynamics, and an iterative method for the nonlinear HJB equation associated to the feedback synthesis. The latter is known as the Successive Galerkin Approximation. It can also be interpreted as Newton iteration for the HJB equation. At every step, the associated linear Generalized HJB equation is approximated via a separable polynomial approximation ansatz. Stabilizing feedback controls are obtained from solutions to the HJB equations for systems of dimension up to fourteen. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.04400v2.pdf"}
{"id": "1702.07217", "abstract": "  Using transfer operator and fundamental measure theories, we examine the structural and thermodynamic properties of hard rectangles confined between two parallel hard walls. The side lengths of the rectangle (L and D, L>D) and the pore width (H) are chosen such that maximum two layers are allowed to form in planar order (L is parallel to the wall), while only one in homeotropic order (D is parallel to the wall). We observe three different structures: (i) a low density fluid phase with parallel alignment to the wall, (ii) an intermediate and high density fluid phase with two layers and planar ordering and (iii) a dense single fluid layer with homeotropic ordering. The appearance of these phases and the change in the ordering direction with density is a consequence of the varying close packing structures with L and H. Interestingly, even three different structures can be observed with increasing density if L is close to H. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.07217v1.pdf"}
{"id": "astro-ph0001337", "abstract": "  We use recent HST colour-magnitude diagrams of the resolved stellar populations of a sample of local dSph galaxies (Carina, LeoI, LeoII, Ursa Minor and Draco) to infer the star formation histories of these systems, SFR(t). Applying a new variational calculus maximum likelihood method which includes a full Bayesian analysis and allows a non-parametric estimate of the function one is solving for, we infer the star formation histories of the systems studied. This method has the advantage of yielding an objective answer, as one need not assume a priori the form of the function one is trying to recover. The results are checked independently using Saha's W statistic. The total luminosities of the systems are used to normalize the results into physical units and derive SN type II rates. We derive the luminosity weighted mean star formation history of this sample of galaxies. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0001/0001337v1.pdf"}
{"id": "astro-ph0002474", "abstract": "  We present Keck R and I band images of the field of the anomalous X-ray pulsar 1E 2259+58.6. We derive an improved X-ray position from archival ROSAT HRI observations by correcting for systematic (boresight) errors. Within the corresponding error circle, no object is found on the Keck images, down to limiting magnitudes R = 25.7 and I = 24.3. We discuss the constraints imposed by these limits, and conclude that it is unlikely that 1E 2259+58.6 is powered by accretion from a disk, irrespective of whether it is in a binary or not, unless the binary is extremely compact. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0002/0002474v1.pdf"}
{"id": "astro-ph0004156", "abstract": "  We investigate some aspects of quintessence models with a non-minimally coupled scalar field and in particular we show that it can behave as a component of matter with -3 ≲ P/ρ≲ 0. We study the properties of gravitational waves in this class of models and discuss their energy spectrum and the cosmic microwave background anisotropies they induce. We also show that gravitational waves are damped by the anisotropic stress of the radiation and that their energy spectrum may help to distinguish between inverse power law potential and supergravity motivated potential. We finish by a discussion on the constraints arising from their density parameter Ω_. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0004/0004156v2.pdf"}
{"id": "astro-ph0004378", "abstract": "  The Tycho-2 Catalogue, released in February 2000, is based on the ESA Hipparcos space mission data and various ground-based catalogs for proper motions. An external comparison of the Tycho-2 astrometry is presented here using the first U.S. Naval Observatory CCD Astrograph Catalog (UCAC1). The UCAC1 data were obtained from observations performed at CTIO between February 1998 and November 1999, using the 206 mm aperture 5-element lens astrograph and a 4k x 4k CCD. Only small systematic differences in position between Tycho-2 and UCAC1 up to 15 milliarcseconds (mas) are found, mainly as a function of magnitude. The standard deviations of the distributions of the position differences are in the 35 to 140 mas range, depending on magnitude. The observed scatter in the position differences is about 30", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0004/0004378v1.pdf"}
{"id": "astro-ph0005057", "abstract": "  The spatial distribution of sources populating different regions of the colour-magnitude diagram (I-J, I) extracted from the DENIS catalogue towards the Magellanic Clouds (DCMC – Cioni et al. 2000) reveal significantly different morphologies. Each region is associated to a different age group. The Large Magellanic Cloud (LMC) shows an extended circular shape with a prominent, off center bar, a nucleus and irregular spiral arms. The Small Magellanic Cloud shows a perturbated structure with a prominent central concentration of stars. Old and young populations are offset from one another. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0005/0005057v1.pdf"}
{"id": "astro-ph0008195", "abstract": "  We have studied the evolution of galaxian morphologies from ground-based, good-seeing images of 9 clusters at z=0.09-0.25. The comparison of our data with those relative to higher redshift clusters (Dressler et al. 1997) allowed us to trace for the first time the evolution of the morphological mix at a look-back time of 2-4 Gyr, finding a dependence of the observed evolutionary trends on the cluster properties. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0008/0008195v1.pdf"}
{"id": "astro-ph0011447", "abstract": "  We study the spectra generated as a result of bulk Comptonization by relativistic electrons in radial flows onto compact objects. We solve numerically the general-relativistic radiative transfer equation in the Schwarzschild spacetime, in steady-state and under minimal assumptions. We show that power-law spectra result from multiple scatterings, in a way similar to thermal Comptonization. We also find that photon-electron interactions taking place near the black-hole event horizon affect very little the emerging spectra. We, therefore, argue that bulk Comptonization spectra do not carry distinguishing signatures of the compact object around which they are produced. We examine the dependence of the spectra on simplifications often employed regarding the spacetime geometry, the distribution of photon sources, and the boundary conditions. We show that the existence of trapped characteristics around a black hole reduces the efficiency of Comptonization and that general relativistic effects identically cancel bulk Comptonization effects for a free-falling flow and in the limit of infinitesimal mean-free path. As a result, we find that neglecting the curved spacetime geometry leads to overestimating the high-energy flux by up to an order of magnitude. Finally, we demonstrate that the spectrum from accretion onto a neutron star depends sensitively on the imposed boundary conditions, while that from a black hole is immune to such choices. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0011/0011447v1.pdf"}
{"id": "astro-ph0011549", "abstract": "  The tailed radio galaxies that have been called “Type I” are not a uniform set. To study their dynamics, we have used the Ledlow-Owen data set, which provides a new sample of 250 radio galaxies in nearby Abell clusters. These sources divide into two clear categories based on their radio morphology. Type A sources (“straight”) contain nearly straight jets which are embedded in outer radio lobe. Type B sources (“tailed”) have a well-collimated jet flow which undergoes a sudden transition, at an inner hot spot, to a less collimated flow which continues on and forms a radio tail. We have not found any separation of these classes in terms of radio power, radio flux size, galaxy power or external gas density. We propose the difference is due to the development, or not, of a disruptive flow instability, such as Kelvin-Helmholtz, and the saturation of the instability when it develops. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0011/0011549v1.pdf"}
{"id": "astro-ph0103140", "abstract": "  We report on ASCA, RXTE, and archival observations of the high mass X-ray binary pulsar 4U1907+09. Spectral measurements of the absorption and flux were made at all phases of the X-ray pulsar orbit, including the first spectral measurements of an extended period of low flux during two of the ASCA observations. We find that a simple spherical wind model can fit the time averaged light curve as measured by the RXTE ASM, but does not fit the observed changes in the absorption column or account for the existence of the phase-locked secondary flare. An additional model component consisting of a trailing stream can account for the variations in column depth. However, these models favor a high inclination angle for the system, suggesting a companion mass more consistent with an identification as a Be-star. In this case an equatorially enhanced wind and inclined neutron star orbit may be a more appropriate interpretation of the data. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0103/0103140v1.pdf"}
{"id": "astro-ph0103356", "abstract": "  HIRES processing provides a significant improvement in both resolution and image quality over previous IRAS image products, but the characteristics of the HIRES beam make accurate comparisons between the various IRAS bandpasses and between HIRES data and data at other wavelengths non-trivial. We present a new, fast technique for the construction of HIRES beam-matched images that is especially well suited for the creation of large-scale (several square degrees) ratio maps. Other techniques for the construction of ratio maps are discussed and compared with the new algorithm. Examples of the large-scale ratio maps that can be constructed using this new technique are presented. The algorithm's application to the construction of multiwavelength difference images and multi-colour images is also demonstrated. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0103/0103356v1.pdf"}
{"id": "astro-ph0106358", "abstract": "  We present the results of N-body simulations of the accretion of high-density dwarf galaxies by low-density giant galaxies. Both galaxies contain power-law central density cusps and point masses representing supermassive black holes; the ratio of galaxy masses is 3:1. The cusp of the dwarf galaxy is always disrupted during the merger, leading to a remnant with a weak power law in the intrinsic density and a “core” in the projected density. Removing both black holes from the giant and dwarf galaxies allows the dwarf galaxy to remain intact and leads to a remnant with a high central density, contrary to what is observed. Our results support the hypothesis than the persistence of low-density cores in giant galaxies following mergers is a consequence of the existence of supermassive central black holes. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0106/0106358v1.pdf"}
{"id": "astro-ph0106513", "abstract": "  A neutron star in binary orbit with a low-mass non-degenerate companion becomes a source of x-rays with millisecond variability when mass accretion spins it up. Centrifugally driven changes in density profile may initiate a phase transition in a growing region of the core parallel to what may take place in an isolated millisecond pulsar, but in reverse. Such a star will spend a longer time in the spin frequency range over which the transition occurs than elsewhere because the change of phase, paced by the spinup rate, is accompanied by a growth in the moment of inertia. The population of accreters will exhibit a clustering in the critical frequency range. A phase change triggered by changing spin and the accompanying adjustment of moment of inertia has its analogue in rotating nuclei. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0106/0106513v1.pdf"}
{"id": "astro-ph0108058", "abstract": "  Many of the fundamental questions in astrophysics can be addressed using spectroscopic observations of photoionized cosmic plasmas. However, the reliability of the inferred astrophysics depends on the accuracy of the underlying atomic data used to interpret the collected spectra. In this paper, we review some of the most glaring atomic data needs for better understanding photoionized plasmas. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0108/0108058v1.pdf"}
{"id": "astro-ph0108494", "abstract": "  Imaging and spectroscopic observations in the mid-infrared wavelength range (5μm–30μm) offer valuable insight into the origins of stars and planets. Sensitive new array detectors on 8-meter class telescopes make it possible to study a wide range of phenomena, from protoplanetary disks to starburst galaxies, in unprecedented detail. I review the capablities of ground-based mid-infrared instruments (e.g., high spatial resolution) and their limitations (e.g., poor sensitivity, small field of view) using several examples in the field of star formation, and discuss prospects for the near future. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0108/0108494v1.pdf"}
{"id": "astro-ph0110075", "abstract": "  We performed a new analysis of B and R light curves of a sample of PG quasars. We confirm the variability-redshift correlation and its explanation in terms of spectral variability, coupled with the increase of rest-frame observing frequency for quasars at high redshift. The analysis of the instantaneous spectral slope for the whole quasar samples indicates both an inter-QSO and intra-QSO variability-luminosity correlation. Numerical simulations show that the latter correlation cannot be entirely due to the addition of the host galaxy emission to a nuclear spectrum of variable luminosity but constant shape, implying a spectral variability of the nuclear component. Changes of accretion rate are also insufficient to explain the amount of spectral variation, while hot spots possibly caused by local disk instabilities can explain the observations. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0110/0110075v1.pdf"}
{"id": "astro-ph0111131", "abstract": "  This paper describes updated predictions, as a function of the underlying cosmological model, for a serendipitous galaxy cluster survey that we plan to conduct with the XMM-Newton X-ray Satellite. We have included the effects of the higher than anticipated internal background count rates and have expanded our predictions to include clusters detected at 3 sigma. Even with the enhanced background levels, we expect the XCS to detect sufficient clusters at z>1 to differentiate between open and flat cosmological models. We have compared the XCS cluster redshift distribution to those expected from the XMM Slew Survey and the ROSAT Massive Cluster Survey (MACS) and find them to be complementary. We conclude that the future existence of the XCS should not deter the launch of a dedicated X-ray survey satellite. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0111/0111131v1.pdf"}
{"id": "astro-ph0112192", "abstract": "  We analyze the Time-Tagged Event (TTE) data from observations of gamma ray bursts (GRBs) and soft gamma repeaters (SGRs) by the Burst and Transient Source Experiment (BATSE). These data provide the best available time resolution for GRBs and SGRs. We have performed an extensive search for weak periodic signals in the frequency range 400 Hz to 2500 Hz using the burst records for 2203 GRBs and 152 SGR flares. The study employs the Rayleigh power as a test statistic to evaluate the evidence for periodic emissions. We find no evidence of periodic emissions from these events at these frequencies. In all but a very few cases the maximum power values obtained are consistent with what would be expected by chance from a non-periodic signal. In those few instances where there is marginal evidence for periodicity there are problems with the data that cast doubt on the reality of the signal. For classical GRBs, the largest Rayleigh power occurs in bursts whose TTE data appear to be corrupted. For SGRs, our largest Rayleigh power, with a significance of 1", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0112/0112192v1.pdf"}
{"id": "astro-ph0112239", "abstract": "  After a couple of years of quiescence, the soft gamma repeater SGR 1900+14 suddenly reactivated on 18 April 2001, with the emission of a very intense, long and modulated flare, only second in intensity and duration to the 27 August 1998 giant flare. BeppoSAX caught the large flare with its Gamma Ray Burst Monitor and with one of the Wide Field Cameras. The Wide Field Cameras also detected X-ray bursting activity shortly before the giant flare. A target of opportunity observation was started only 8 hours after the large flare with the Narrow Field Instruments, composed of two 60-ks long pointings. These two observations show an X-ray afterglow of the persistent SGR 1900+14 source, decaying with time according to a power law of index -0.6. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0112/0112239v1.pdf"}
{"id": "astro-ph0112437", "abstract": "  We study the dynamics of phase transitions in the interstellar medium by means of three-dimensional hydrodynamic numerical simulations. We use a realistic cooling function and generic nonequilibrium initial conditions to follow the formation history of a multiphase medium in detail in the absence of gravity. We outline a number of qualitatively distinct stages of this process, including a linear isobaric evolution, transition to an isochoric regime, formation of filaments and voids (also known as \"thermal\" pancakes), the development and decay of supersonic turbulence, an approach to pressure equilibrium, and final relaxation of the multiphase medium. We find that 1", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0112/0112437v2.pdf"}
{"id": "astro-ph0206360", "abstract": "  We present the mass function (MF) of the Arches cluster obtained from ground-based adaptive optics data in comparison with results derived from HST/NICMOS data. A MF slope of Gamma = -0.8 +- 0.2 is obtained. Both datasets reveal a strong radial variation in the MF, with a flat slope in the cluster center, which increases with increasing radius. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0206/0206360v1.pdf"}
{"id": "astro-ph0208098", "abstract": "  We discuss optical colors of 10,592 asteroids with known orbits selected from a sample of 58,000 moving objects observed by the Sloan Digital Sky Survey (SDSS). This is more than ten times larger sample that includes both orbital parameters and multi-band photometric measurements than previously available. We confirm that asteroid dynamical families, defined as clusters in orbital parameter space, also strongly segregate in color space. In particular, we demonstrate that the three major asteroid families (Eos, Koronis, and Themis), together with the Vesta family, represent four main asteroid color types. Their distinctive optical colors indicate that the variations in chemical composition within a family are much smaller than the compositional differences between families, and strongly support earlier suggestions that asteroids belonging to a particular family have a common origin. We estimate that over 90", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0208/0208098v1.pdf"}
{"id": "astro-ph0208383", "abstract": "  We have identified the 1.4 GHz radio source FIRST J102347.6+003841 (hereafter FIRST J1023+0038) with a previously unknown 17th-mag Galactic cataclysmic variable (CV). The optical spectrum resembles that of a magnetic (AM Herculis- or DQ Herculis-type) CV. Five nights of optical CCD photometry showed variations on timescales of minutes to hours, along with rapid flickering. A re-examination of the FIRST radio survey data reveals that the radio detection was based on a single 6.6 mJy flare; on two other occasions the source was below the  1 mJy survey limit. Several other magnetic CVs are known to be variable radio sources, suggesting that FIRST J1023+0038 is a new member of this class (and the first CV to be discovered on the basis of radio emission). However, FIRST J1023+0038 is several optical magnitudes fainter than the other radio-detected magnetic CVs. It remains unclear whether the source simply had a very rare and extraordinarily intense radio flare at the time of the FIRST observation, or is really an unusually radio-luminous CV; thus further observations are urged. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0208/0208383v1.pdf"}
{"id": "astro-ph0209348", "abstract": "  We present a spatially resolved spectroscopic analysis of the young Galactic supernova remnant Kes 75 (SNR G29.7-0.3) using the Chandra X-ray Observatory. Kes 75 is one of an increasing number of examples of a shell-type remnant with a central pulsar powering an extended radio/X-ray core. We are able to pinpoint the location of the recently discovered pulsar, PSR J1846-0258, and confirm that X-rays from the remnant's core component are consistent with non-thermal power-law emission from both the pulsar and its surrounding wind nebula. We find that the spectrum of the pulsar is significantly harder than that of the wind nebula. Fainter, diffuse emission is detected from throughout the volume delineated by the radio shell with a surface brightness distribution strikingly similar to the radio emission. The presence of strong lines attributable to ionized Mg, Si, and S indicate that at least some of this emission is thermal in nature. However, when we characterize the emission using a model of an underionized plasma with non-solar elemental abundances, we find we require an additional diffuse high-energy component. We show that a significant fraction of this emission is an X-ray scattering halo from the pulsar and its wind nebula, although a nonthermal contribution from electrons accelerated in the shock cannot be excluded. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0209/0209348v1.pdf"}
{"id": "astro-ph0211251", "abstract": "  We present a new set of dissipationless N-body simulations aiming to better understand the pure dynamical aspects of the “Fundamental Plane” (FP) of elliptical galaxies. We have extended our previous hierarchical merger scheme by considering the Hernquist profile for the initial galaxy model. Two-component Hernquist galaxy models were also used to study the effect of massive dark halos on the end-products characteristics. We have also performed new collapse simulations including initial spin. We found that the one-component Hernquist mergers give results similar to those found for the one-component King models, namely both were able to build-up small scatter FP-like correlations with slopes consistent with what is found for the near-infrared FP of nearby galaxies. The two-component models also reproduce a FP-like correlation, but with a significantly steeper slope. This is in agreement with what has been found for elliptical galaxies at higher redshift (0.1 < z < 0.6). We discuss some structural properties of the simulated galaxies and their ability to build-up FP-like correlations. We confirm that collapses generally do not follow a FP-like correlation regardless of the initial spin. We suggest that the evolution of gradients in the gravitational field of the merging galaxies may be the main ingredient dictating the final non-homology property of the end products. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0211/0211251v1.pdf"}
{"id": "astro-ph0212034", "abstract": "  Absorption and Reprocessing of Gamma-ray burst radiation in the environment of cosmological GRBs can be used as a powerful probe of the elusive nature of their progenitors. In particular, transient X-ray emission line and absorption features in the prompt and early afterglows of GRBs are sensitive to details of the location and density structure of the reprocessing and/or absorbing material. To date, there have been only rather few detections of such features, and the significance is marginal in most individual cases. However, transient X-ray emission lines in GRB afterglows have now been found by four different X-ray satellites, which may justify a more detailed theoretical investigation of their origin. In this paper, I will first present a brief review of the status of observations of transient X-ray emission line and absorption features. I will then discuss general physics constraints which those results impose on isotropy, homogeneity, and location of the reprocessing material with respect to the GRB source, and review the various currently discussed, specific models of GRBs and their environments in which the required conditions could arise. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0212/0212034v1.pdf"}
{"id": "astro-ph0212524", "abstract": "  Light curves of eight BL Lac objects in the BVRI bands have been analyzed. All of the objects tend to be bluer when brighter. However spectral slope changes differ quantitatively from those of a sample of QSOs analyzed in a previous paper (Trevese     Vagnetti 2002) and appear consistent with a different nature of the optical continuum. A simple model representing the variability of a synchrotron component can explain the spectral changes. Constraints on a possible thermal accretion disk component contributing to the optical luminosity are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0212/0212524v2.pdf"}
{"id": "astro-ph0303583", "abstract": "  The compact radio source Sgr A*, believed to be the counterpart of the massive black hole at the Galactic nucleus, was observed to undergo rapid and intense flaring activity in X-rays with Chandra in October 2000. We report here the detection with XMM-Newton EPIC cameras of the early phase of a similar X-ray flare from this source, which occurred on 2001 September 4. The source 2-10 keV luminosity increased by a factor   20 to reach a level of 4 10^34 erg s^-1 in a time interval of about 900 s, just before the end of the observation. The data indicate that the source spectrum was hard during the flare and can be described by simple power law of slope   0.7. This XMM-Newton observation confirms the results obtained by Chandra, suggests that, in Sgr A*, rapid and intense X-ray flaring is not a rare event and therefore sets some constraints on the emission mechanism models proposed for this source. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0303/0303583v1.pdf"}
{"id": "astro-ph0308154", "abstract": "  The black hole X-ray binary V4641 Sgr experienced an outburst in 2002 May which was detected at X-ray, optical, and radio wavelengths. The outburst lasted for only 6 days, but the object remained active for the next several months. Here we report on the detailed properties of light curves during the outburst and the post-outburst active phase. We reveal that rapid optical variations of  100 s became more prominent when a thermal flare weakened and the optical spectrum flattened in the Ic, Rc, and V-band region. In conjunction with the flat spectrum in the radio range, this strongly indicates that the origin of rapid variations is not thermal emission, but synchrotron emission. Just after the outburst, we detected repeated flares at optical and X-ray wavelengths. The optical and X-ray light curves exhibited a strong correlation, with the X-rays, lagging by about 7 min. The X-ray lag can be understood in terms of a hot region propagating into the inner region of the accretion flow. The short X-ray lag, however, requires modifications of this simple scenario to account for the short propagation time. We also detected rapid optical variations with surprisingly high amplitude 50 days after the outburst, which we call optical flashes. During the most prominent optical flash, the object brightened by 1.2 mag only within 30 s. The released energy indicates that the emission source should be at the innermost region of the accretion flow. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0308/0308154v1.pdf"}
{"id": "astro-ph0309431", "abstract": "  We report here detailed timing and spectral analysis of two Beppo-SAX observations of the binary X-ray pulsar LMC X-4 carried out during the low and high states of its 30.5 days long super-orbital period. Timing analysis clearly shows 13.5 s X-ray pulsations in the high state of the super-orbital period which allows us to measure the mid-eclipse time during this observation. Combining this with two other mid-eclipse times derived earlier with the ASCA, we derived a new estimate of the orbital period derivative. Pulse-phase averaged spectroscopy in the high and low states shows that the energy spectrum in the 0.1 - 10 keV band comprises of a hard power-law, a soft excess, and a strong iron emission line. The continuum flux is found to decrease by a factor of   60 in the low state while the decrease in the iron line flux is only by a factor of   12, suggesting a different site for the production of the line emission. In the low state, we have not found any significant increase in the absorption column density. The X-ray emission is found to come from a very large region, comparable to the size of the companion star. Pulse phase resolved spectroscopy in the high state shows a pulsating nature of the soft spectral component with some phase offset compared to the hard X-rays, as is known in some other binary X-ray pulsars. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0309/0309431v1.pdf"}
{"id": "astro-ph0312396", "abstract": "  In all the microquasars with two hHz QPOs, the ratio of the frequencies is 3:2, supporting our suggestion that a non-linear resonance between two modes of oscillation in the accretion disk plays a role in exciting the observed modulations of the X-ray flux. We discuss the evidence in favor of this interpretation, and we relate the black hole spin to the frequencies expected for various types of resonances that may occur in nearly Keplerian disks in strong gravity. For those microquasars where the mass of the central X-ray source is known, the black hole spin can be deduced from a comparison of the observed and expected frequencies. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0312/0312396v1.pdf"}
{"id": "astro-ph0401218", "abstract": "  Radial velocities of 468 globular clusters around NGC 1399, the central galaxy in the Fornax cluster, have been obtained with FORS2 and the Mask Exchange Unit (MXU) at the ESO Very Large Telescope. This is the largest sample of globular cluster velocities around any galaxy obtained so far. The mean velocity uncertainty is 50 km/sec. This data sample is accurate and large enough to be used in studies of the mass distribution of NGC 1399 and the properties of its globular cluster system. Here we describe the observations, the reduction procedure, and discuss the uncertainties of the resulting velocities. The complete sample of cluster velocities which is used in a dynamical study of NGC 1399 is tabulated. A subsample is compared with previously published values. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0401/0401218v1.pdf"}
{"id": "astro-ph0403642", "abstract": "  A 20-hour VLBI observation with the NRAO VLBA and GBT in the NOAO Bootes field reaches an rms noise of 9 microJy per beam at 1.4 GHz. Three sources were detected at 10-milliarcsecond resolution within the GBT primary beam of FWHM 8.6', including the 20-milliJy calibrator and two sub-milliJy sources. By tapering the visibility data, portions of the VLBA primary beam of FWHM 29' were imaged at poorer sensitivity and resolution to yield five further detections. New developments at JIVE will permit deeper and wider VLBI surveys at full sensitivity and resolution, enabling new types of survey science. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0403/0403642v1.pdf"}
{"id": "astro-ph0404499", "abstract": "  The 511 keV emission from the Galactic Bulge observed by INTEGRAL/SPI could be the product of light (1-100 MeV) annihilating dark matter particles. In order to distinguish between annihilating light dark matter scenarios and more conventional astrophysical sources for the bulge emission, we propose to test the light dark matter hypothesis on the Sagittarius Dwarf Galaxy, a close-by galaxy dominated by dark matter. The predicted flux being in the SPI sensitivity range, the detection of a substantial 511 keV emission line from this galaxy would provide a strong evidence for the light dark matter hypothesis.   During the two Galactic Center Deep Exposures performed in 2003, the Sagittarius Dwarf Galaxy was in the field of view of several INTEGRAL observations. In this paper we present preliminary results of the analysis of these data. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0404/0404499v1.pdf"}
{"id": "astro-ph0405624", "abstract": "  As part of the In-Orbit Checkout activities for the Spitzer Space Telescope, the IRAC team carried out a deep observation (average integration time  8 hours) of a field surrounding the bright QSO HS 1700+6416. This field contains several hundred z 3 Lyman-break galaxy candidates, and we report here on their mid-infrared properties, including the IRAC detection rate, flux densities and colors, and the results of fitting population synthesis models to the optical, near-infrared, and IRAC magnitudes. The results of the model-fitting show that previous optical/near-infrared studies of LBGs were not missing large, hidden old stellar populations. The LBG candidates' properties are consistent with those of massive, star-forming galaxies at z 3. Other IRAC sources in the same field have similar properties, so IRAC selection may prove a promising method of finding additional high-redshift galaxies. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0405/0405624v1.pdf"}
{"id": "astro-ph0406428", "abstract": "  By cross-correlating templates constructed from the 2 Micron All Sky Survey (2MASS) Extended Source (XSC) catalogue with WMAP's first year data, we search for the thermal Sunyaev-Zel'dovich signature induced by hot gas in the local Universe. Assuming that galaxies trace the distribution of hot gas, we select regions on the sky with the largest projected density of galaxies. Under conservative assumptions on the amplitude of foreground residuals, we find a temperature decrement of -35 ± 7 μK (∼ 5σ detection level, the highest reported so far) in the ∼ 26 square degrees of the sky containing the largest number of galaxies per solid angle. We show that most of the reported signal is caused by known galaxy clusters which, when convolved with the average beam of the WMAP W band channel, subtend a typical angular size of 20–30 arcmins. Finally, after removing from our analyses all pixels associated with known optical and X-ray galaxy clusters, we still find a tSZ decrement of -96 ± 37 μK in pixels subtending about ∼ 0.8 square degrees on the sky. Most of this signal is coming from five different cluster candidates in the Zone of Avoidance (ZoA), present in the Clusters In the ZoA (CIZA) catalogue. We found no evidence that structures less bound than clusters contribute to the tSZ signal present in the WMAP data. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0406/0406428v2.pdf"}
{"id": "astro-ph0408097", "abstract": "  We describe a procedure for accurately determining luminosity distances to Type Ia supernovae (SNe Ia) without knowledge of redshift. This procedure, which may be used as an extension of any of the various distance determination methods currently in use, is based on marginalizing over redshift, removing the requirement of knowing z a priori. We demonstrate that the Hubble diagram scatter of distances measured with this technique is approximately equal to that of distances derived from conventional redshift-specific methods for a set of 60 nearby SNe Ia. This indicates that accurate distances for cosmological SNe Ia may be determined without the requirement of spectroscopic redshifts, which are typically the limiting factor for the number of SNe that modern surveys can collect. Removing this limitation would greatly increase the number of SNe for which current and future SN surveys will be able to accurately measure distance. The method may also be able to be used for high-z SNe Ia to determine cosmological density parameters without redshift information. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0408/0408097v1.pdf"}
{"id": "astro-ph0409160", "abstract": "  A-type supergiants are primary targets for quantitative spectroscopy of individual stars in nearby galaxies because of their intrinsic brightness. An overview is given on the non-LTE techniques required for their analysis. Applications concentrate on placing observational constraints on evolutionary models for massive stars and their host galaxies by detailed abundance analyses. Results from high-resolution studies of A-type supergiants in Local Group galaxies and from intermediate-resolution multi-object spectroscopy of supergiants far beyond the Local Group are summarised. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0409/0409160v1.pdf"}
{"id": "astro-ph0409520", "abstract": "  XMM-Newton and the VLA simultaneously observed the eclipsing Algol-type binary RZ Cassiopeiae in August 2003. The secondary eclipse (K3 IV companion behind the A3 V primary) was placed at the center of the 15-hour radio campaign, while the X-ray satellite monitored a full 1.2-day orbital period. We present results of the X-ray and radio campaigns. The X-ray light curve shows significant modulation probably related to rotational modulation and active region evolution, and even small flares. However, the X-ray eclipse is not deep, implying that the coronal X-ray emitting material is spatially extended. The Reflection Grating Spectrometer (RGS) spectrum shows a variety of bright emission lines from Fe, Ne, O, N. A strong [C/N] depletion probably reflects the surface composition of the secondary which fills its Roche lobe and loses material onto the primary. The O vii He-like triplet reflects a low forbidden-to-intercombination ratio; while it generally suggests high electron densities, the ratio is here modified by photoexcitation by the strong UV flux of the primary A3 V star. The radio light curve shows no similarity to the X-ray light curve. The eclipse timings are different, and the radio flux increased while the X-ray flux decreased. The radio spectral slope is shallow (α = 0 - 1). ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0409/0409520v1.pdf"}
{"id": "astro-ph0410090", "abstract": "  High velocity outflows from supermassive black holes have been invoked to explain the recent identification of strong absorption features in the hard X-ray spectra of several quasars. Here, Monte Carlo radiative transfer calculations are performed to synthesise X-ray spectra from models of such flows. It is found that simple, parametric bi-conical outflow models with plausible choices for the wind parameters predict spectra that are in good qualitative agreement with observations in the 2 - 10 keV band. The influence on the spectrum of both the mass-loss rate and opening angle of the flow are considered: the latter is important since photon leakage plays a significant role in establishing an ionization gradient within the flow, a useful discriminant between spherical and conical outflow for this and other applications. Particular attention is given to the bright quasar PG1211+143 for which constraints on the outflow geometry and mass-loss rate are discussed subject to the limitations of the currently available observational data. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0410/0410090v1.pdf"}
{"id": "astro-ph0501129", "abstract": "  There have been recent downward revisions of the solar photospheric abundances of Oxygen and other heavy elements. These revised abundances along with OPAL opacities are not consistent with seismic constraints. In this work we show that the recently released OP opacity tables cannot resolve this discrepancy either. While the revision in opacities does not seem to resolve this conflict, an upward revision of Neon abundance in solar photosphere offers a possible solution to this problem. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0501/0501129v1.pdf"}
{"id": "astro-ph0506397", "abstract": "  The Gaia satellite was selected as a cornerstone mission of the European Space Agency (ESA) in October 2000 and confirmed in 2002 with a current target launch date of 2011. The Gaia mission will gather on the same observational principles as Hipparcos detailed astrometric, photometric and spectroscopic properties of about 1 billion sources brighter than mag V=20. The nature of the measured objects ranges from NEOs to gamma ray burst afterglows and encompasses virtually any kind of stars in our Galaxy. Gaia will provide multi-colour (in about 20 passbands extending over the visible range) photometry with typically 250 observations distributed over 40 well separated epochs during the 5-year mission. The multi-epoch nature of the project will permit to detect and analyse variable sources whose number is currently estimated in the range of several tens of million, among the detectable sources.   In this paper, we assess the performances of Gaia in analysing photometric periodic phenomena. We first present quickly the overall observational principle before discussing the implication of the scanning law in the time sampling. Then from extensive simulations one assesses the performances in the recovery of periodic signals as a function of the period, signal-to-noise ratio and position on the sky for simple sinusoidal variability. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0506/0506397v1.pdf"}
{"id": "astro-ph0507259", "abstract": "  Observations made of the X-ray pulsar EXO 1722-363 using the Proportional Counter Array and All Sky Monitor on board the Rossi X-ray Timing Explorer reveal the orbital period of this system to be 9.741 +/- 0.004 d from periodic changes in the source flux. The detection of eclipses, together with the values of the pulse and orbital periods, suggest that this source consists of a neutron star accreting from the stellar wind of an early spectral type supergiant companion. Pulse timing measurements were also obtained but do not strongly constrain the system parameters. The X-ray spectra can be well fitted with a model consisting of a power law with a high energy cutoff and, for some spectra, a blackbody component with a temperature of approximately 0.85 keV. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0507/0507259v1.pdf"}
{"id": "astro-ph0511443", "abstract": "  We review basic physics of line-driven stellar winds of OB stars. We discuss elementary processes due to which stellar winds are accelerated on a microscopic level. We show how these microscopic processes may enable the outflow and how they determine wind properties on a macroscopic level. We discuss shortcomings of present wind theories and future wind model improvements. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0511/0511443v1.pdf"}
{"id": "astro-ph0511603", "abstract": "  A popular self–enrichment scenario for the formation of globular clusters assumes that the abundance anomalies shown by the stars in many clusters are due to a second stage of star formation occurring from the matter lost by the winds of massive asymptotic giant branch (AGB) stars. Until today, the modellizations of the AGB evolution by several different groups failed, for different reasons, to account for the patterns of chemical anomalies. Here we show that our own modelling can provide a consistent picture if we constrain the three main parameters which regulate AGB evolution: 1) adopting a high efficiency convection model; 2) adopting rates of mass loss with a high dependence on the stellar luminosity; 3) assuming a very small overshooting below the formal convective regions during the thermal pulse (TP) phase. The first assumption is needed to obtain an efficient oxygen depletion in the AGB envelopes, and the second one is needed to lose the whole stellar envelope within few thermal pulses, so that the sum of CNO elements does not increase too much, consistently with the observations. The third assumption is needed to fully understand the sodium production. We also show that the Mg - Al anticorrelation is explained adopting the higher limit of the NACRE rates for proton captures by Mg25 and Mg26, and the models are consistent with the recently discovered F-Al correlation. Problems remain to fully explain the observed Mg isotopes ratios. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0511/0511603v1.pdf"}
{"id": "astro-ph0602332", "abstract": "  We report on time-resolved photometry of the 2005 July superoutburst of the dwarf nova, 2QZ J021927.9-304545. The resultant light curves showed conspicuous superhumps with a period of 0.081113(19) days, confirming the SU UMa nature of the object. Although we missed the maximum phase of the outburst, the amplitude of the superoutburst well exceeded 5 mag. This value is slightly larger than that of typical SU UMa-type dwarf novae. The superhump period decreased as time elapsed, as can be seen in most SU UMa-type dwarf novae. Based on the archive of ASAS-3, the recurrence time of a superoutburst of the variable turned out to be about 400 days. This value is typical of well known SU UMa stars. The distance to this system was roughly estimated as 370(+20, -60) pc using an empirical relation. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0602/0602332v1.pdf"}
{"id": "astro-ph0605385", "abstract": "  The expansion of the electron-positron plasma in the GRB phenomenon is compared and contrasted in the treatments of Meszaros, Laguna and Rees, of Shemi, Piran and Narayan, and of Ruffini et al. The role of the correct numerical integration of the hydrodynamical equations, as well as of the rate equation for the electron-positron plasma loaded with a baryonic mass, are outlined and confronted for crucial differences. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0605/0605385v1.pdf"}
{"id": "astro-ph0609418", "abstract": "  We present a fast and efficient hybrid algorithm for selecting exoplanetary candidates from wide-field transit surveys. Our method is based on the widely-used SysRem and Box Least-Squares (BLS) algorithms. Patterns of systematic error that are common to all stars on the frame are mapped and eliminated using the SysRem algorithm. The remaining systematic errors caused by spatially localised flat-fielding and other errors are quantified using a boxcar-smoothing method. We show that the dimensions of the search-parameter space can be reduced greatly by carrying out an initial BLS search on a coarse grid of reduced dimensions, followed by Newton-Raphson refinement of the transit parameters in the vicinity of the most significant solutions. We illustrate the method's operation by applying it to data from one field of the SuperWASP survey, comprising 2300 observations of 7840 stars brighter than V=13.0. We identify 11 likely transit candidates. We reject stars that exhibit significant ellipsoidal variations indicative of a stellar-mass companion. We use colours and proper motions from the 2MASS and USNO-B1.0 surveys to estimate the stellar parameters and the companion radius. We find that two stars showing unambiguous transit signals pass all these tests, and so qualify for detailed high-resolution spectroscopic follow-up. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0609/0609418v1.pdf"}
{"id": "astro-ph0609578", "abstract": "  We discuss the prospects of using Gamma Ray Bursts (GRBs) as high-redshift distance estimators, and consider their use in the study of two dark energy models, the Generalized Chaplygin Gas (GCG), a model for the unification of dark energy and dark matter, and the XCDM model, a model where a generic dark energy fluid like component is described by the equation of state, p= ωρ. We find that this test yields rather disappointing results for the GCG model, being mainly sensitive to the total amount of matter present in the Universe in the case of the XCDM model. We also find that, within the framework of the XCDM model, a large sample of GRBs (≥ 200) may turn out to be quite useful to improve the forthcoming type Ia supernovae data. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0609/0609578v1.pdf"}
{"id": "astro-ph0612502", "abstract": "  High resolution data in the region of the line Halpha have been obtained at the time of the light maximum and after it of the 2006 optical outburst of the symbiotic binary Z And. A blue-shifted absorption component indicating outflow velocity of about 1400 km/s as well as additional emission components with similar velocities, situated on the two sides of the main peak of the line were observed during that time. It is suggested that all of them are spectral signature of bipolar outflow, observed for the first time in the optical spectrum of this binary. The emission measure and the mass of the nebular part of the streams were estimated approximately. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0612/0612502v1.pdf"}
{"id": "astro-ph0701793", "abstract": "  In the past few years, astronomers have uncovered several very low-temperature, metal-poor stars with halo or thick disk kinematics and peculiar spectral and photometric properties, so-called ultracool subdwarfs. These include the first examples of L subdwarfs - metal-poor analogs of the L dwarf spectral class - and slightly metal-deficient T dwarfs. Ultracool subdwarfs provide useful empirical tests of low temperature atmosphere and evolutionary models, and are probes of the halo mass function down to and below the (metal-dependent) hydrogen burning limit. Here I summarize the optical and near-infrared spectroscopic properties of these objects, review recent research results, and point out scientific issues of interest in this developing subject. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0701/0701793v1.pdf"}
{"id": "astro-ph9703131", "abstract": "  A model scenario has recently been introduced to explain the presence of very strong Li lines in the spectra of some low mass K giant stars (de la Reza et al. 1996). In this scenario all ordinary, Li poor, K giants become Li rich during a short time (∼ 10^5 yr) when compared to the red giant phase of 5 10^7 yr. In this “Li period”, a large part of the stars are associated with an expanding thin circumstellar shell supposedly triggered by an abrupt internal mixing mechanism resulting in a surface new ^7Li enrichment. This letter presents near 40 Li rich K giants known up to now. The distribution of these Li rich giants, along with other 41 observed K giants that have shell, but are not Li rich, in a color-color IRAS diagram confirms this scenario, indicating, also as a new result, that a rapid Li depletion takes place on a time scale of between ∼ 10^3 and 10^5 yr. This model explains the problem of the presence of K giants with far infrared excesses presented by Zuckerman et al. (1995). Other present and future tests of this scenario are briefly discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9703/9703131v1.pdf"}
{"id": "astro-ph9705212", "abstract": "  We present sub-arcsecond resolution imaging of the λ = 2.7 mm continuum emission from the young, embedded system L1551 IRS5 using the nine-element, high-resolution configuration of the BIMA array. The observed emission arises from two compact sources separated by 035, coinciding with the two sources seen at λ = 2 cm and λ = 1.3 cm. When the high resolution data is combined with data from two compact configurations, L1551 IRS5 is argued to consist of a protobinary system separated by ∼50 AU with individual circumstellar disks, a circumbinary structure, and a large-scale envelope. The characteristic masses of the components are: 0.024 M_ for the northern circumstellar disk, 0.009 M_ for the southern circumstellar disk, 0.04 M_ for the circumbinary material, and 0.28 M_ for the envelope. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9705/9705212v1.pdf"}
{"id": "astro-ph9708032", "abstract": "  We examine the distribution of masses of black holes in transient low mass X-ray binary systems. A Bayesian analysis suggests that it is probable that six of the seven systems with measured mass functions have black hole masses clustered near seven solar masses. There appears to be a significant gap between the masses of these systems and those of the observed neutron stars. The remaining source, V404 Cyg, has a mass significantly larger than the others, and our analysis suggests that it is probably drawn from a different distribution. Selection effects do not appear to play a role in producing the observed mass distribution, which may be explained by currently unknown details of the supernova explosions and of binary evolution prior to the supernova. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9708/9708032v2.pdf"}
{"id": "astro-ph9711124", "abstract": "  Large-scale structure distorts the images of background galaxies, which allows one to measure directly the projected distribution of dark matter in the universe and determine its power spectrum. Here we address the question of how to extract this information from the observations. We derive minimum variance estimators for projected density reconstruction and its power spectrum and apply them to simulated data sets, showing that they give a good agreement with the theoretical minimum variance expectations. The same estimator can also be applied to the cluster reconstruction, where it remains a useful reconstruction technique, although it is no longer optimal for every application. The method can be generalized to include nonlinear cluster reconstruction and photometric information on redshifts of background galaxies in the analysis. We also address the question of how to obtain directly the 3-d power spectrum from the weak lensing data. We derive a minimum variance quadratic estimator, which maximizes the likelihood function for the 3-d power spectrum and can be computed either from the measurements directly or from the 2-d power spectrum. The estimator correctly propagates the errors and provides a full correlation matrix of the estimates. It can be generalized to the case where redshift distribution depends on the galaxy photometric properties, which allows one to measure both the 3-d power spectrum and its time evolution. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9711/9711124v2.pdf"}
{"id": "astro-ph9712106", "abstract": "  There have been a number of recent spectral models that have been successful in reproducing the observed X-ray spectra of galactic black hole candidates (GBHC). However, there still exists controversy over such issues as: what are the sources of hard radiation, what is the system's geometry, is the accretion efficient or inefficient, etc. A potentially powerful tool for distinguishing among these possibilities, made possible by the Rossi X-ray Timing Explorer (RXTE), is the variability data, especially the observed phase lags and variability coherence. These data, in conjunction with spectral modeling, have the potential of determining physical sizes of the system, as well as placing strong constraints on both Compton corona and advection models. As an example, we present RXTE variability data of Cygnus X-1 ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9712/9712106v1.pdf"}
{"id": "astro-ph9801297", "abstract": "  In dense stars the nuclear reaction rates are influenced by screening effects arising from both ions and electrons. In this paper we calculate the enhancement factors due to electron polarization in the high-density, degenerate and relativistic regime, for non-resonant nuclear reaction rates. In an earlier analysis, Sahrling had proposed the possibility that the polarized electrons would lower the reaction rate instead of enhancing it. This analysis was based on Monte Carlo simulations with only one choice of density, temperature and charge. Here we extend the analysis to a wider range of densities, temperatures and charges and calculate analytical expressions for the enhancement factors. We concentrate on carbon and oxygen ions and show that at very high-densities, high-order quantum effects will be important and act to reduce the zeroth order, classical value for the enhancement factor. We show that in any case, the total electron contribution remains weak, namely an enhancement in the reaction of about a factor 2, contrarily to what had been claimed by some authors in previous calculations. We examine the astrophysical implications of these results on the final stages of massive white dwarfs, near the carbon-ignition curve. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9801/9801297v1.pdf"}
{"id": "astro-ph9805062", "abstract": "  We describe the early results of an investigation into the spectral characteristics of the hottest Am stars (A0 - A2) in an attempt to link the HgMn and Am classes of chemical peculiarity. A limited sample of hot-Am stars was searched for the presence of lines from the very heavy elements platinum and mercury, as well as a search for lines from the rare-earth elements in HgMn stars. Our analysis of the strong optical platinum and mercury lines in the spectrum of the HgMn star HR 7775 has detected isotopic shifts that are different from those found at ultraviolet wavelengths and, in the case of mercury, vary with ionization stage. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9805/9805062v1.pdf"}
{"id": "astro-ph9806043", "abstract": "  First results of a numerical investigation of primordial black hole formation in the radiation dominated phase of the Early Universe are presented. The simulations follow the gravitational collapse of three different families of high-amplitude density fluctuations imposed at the time of horizon crossing. The threshold for black hole formation, δ_c ≈0.7, is found to be nearly identical for all perturbation families if the control parameter, δ, is chosen as the total excess mass within the initial horizon volume. Furthermore, we demonstrate that the scaling of black hole mass with distance from the formation threshold, known to occur in near-critical gravitational collapse, applies to primordial black hole formation. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9806/9806043v1.pdf"}
{"id": "astro-ph9811016", "abstract": "  We present here the first results of a 22cm survey of the Shapley Concentration core. The observations were carried out with the Australia Telescope Compact Array. Our radio observations completely and uniformely cover the A3558 complex, allowing a thorough multifrequency study, by comparison of our results with the available optical spectroscopic and X-ray data of the whole chain.   We will present here some statistical results of our survey and compare them with the information on the dynamics of the chain and on the properties of the intracluster gas. Attention will also be devoted to the extended radio galaxies found in our survey. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9811/9811016v1.pdf"}
{"id": "astro-ph9902130", "abstract": "  We study systematically the  0.1-1200 Hz quasi-periodic oscillations (QPOs) and broad noise components observed in the power spectra of non-pulsing neutron-star and black-hole low-mass X-ray binaries. We show that among these components we can identify two, occurring over a wide range of source types and luminosities, whose frequencies follow a tight correlation. The variability components involved in this correlation include neutron-star kilohertz QPOs and horizontal-branch oscillations, as well as black-hole QPOs and noise components. Our results suggest that the same types of variability may occur in both neutron-star and black-hole systems over three orders of magnitude in frequency and with coherences that vary widely but systematically. Confirmation of this hypothesis will strongly constrain theoretical models of these phenomena and provide additional clues to understanding their nature. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9902/9902130v1.pdf"}
{"id": "astro-ph9904250", "abstract": "  From a rediscussion of Local Group membership, and of distances to individual galaxies, we obtain M_V values for 35 probable and possible Local Group members. The luminosity function of these objects is well fitted by a Schechter function with faint end slope α = -1.1 ± 0.1. The probability that the luminosity distribution of the Local Group is a single Schechter function with α steeper than -1.3 is less than 1 per cent. However, more complicated luminosity functions, such as multi-component Schechter functions with steep faint-end slopes, cannot be ruled out. There is some evidence that the luminosity distribution of dwarf spheroidal galaxies in the Local Group is steeper than that of dwarf irregular galaxies. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9904/9904250v2.pdf"}
{"id": "astro-ph9906279", "abstract": "  An open (having no physical boundaries) baryon symmetric system is considered in a flat space-time. We assume that a space is uniformly filled with electromagnetic radiation and material objects, and the system is isotropic in any inertial reference frame. It means that a coordinate-momentum distribution of radiation and material objects does not depend on a reference frame, and the system should be in a state of chaotic relativistic motion. The dominant interaction processes are like-matter merge, unlike-matter annihilation and pair production. In this approximation we came to the conclusion that matter and antimatter exist in a form of mix of material objects characterized by a stationary baryon symmetric mass distribution in a broad mass range. In other words, a matter-antimatter space separation takes place. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9906/9906279v1.pdf"}
{"id": "astro-ph9908095", "abstract": "  We consider a class of steady-state self-gravitating accretion disks for which efficient cooling mechanisms are assumed to operate so that the disk is self-regulated at a condition of approximate marginal Jeans stability. In an earlier paper, this scenario had been shown to lead naturally, in the absence of a central point mass, to a self-similar solution characterized by a flat rotation curve. In this article we investigate the entire parameter space available for such self-regulated accretion disks and provide two non-trivial extensions of the model. The first extension is that of a bimodal disk, obtained by partially relaxing the self-regulation constraint, so that full matching with an inner \"standard\" Keplerian accretion disk takes place. The second extension is the construction of self-regulated accretion disks embedded in a diffuse spherical \"halo\". The analysis is further strengthened by a careful discussion of the vertical structure of the disk, in such a way that the transition from self-gravity dominated to non-gravitating disks is covered uniformly. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9908/9908095v1.pdf"}
{"id": "astro-ph9908327", "abstract": "  There has recently been interest in the role of inverse bremsstrahlung, the emission of photons by fast suprathermal ions in collisions with ambient electrons possessing relatively low velocities, in tenuous plasmas in various astrophysical contexts. This follows a long hiatus in the application of suprathermal ion bremsstrahlung to astrophysical models since the early 1970s. The potential importance of inverse bremsstrahlung relative to normal bremsstrahlung, i.e. where ions are at rest, hinges upon the underlying velocity distributions of the interacting species. In this paper, we identify the conditions under which the inverse bremsstrahlung emissivity is significant relative to that for normal bremsstrahlung in shocked astrophysical plasmas. We determine that, since both observational and theoretical evidence favors electron temperatures almost comparable to, and certainly not very deficient relative to proton temperatures in shocked plasmas, these environments generally render inverse bremsstrahlung at best a minor contributor to the overall emission. Hence inverse bremsstrahlung can be safely neglected in most models invoking shock acceleration in discrete sources such as supernova remnants. However, on scales > 100pc distant from these sources, Coulomb collisional losses can deplete the cosmic ray electrons, rendering inverse bremsstrahlung, and perhaps bremsstrahlung from knock-on electrons, possibly detectable. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9908/9908327v1.pdf"}
{"id": "astro-ph9909240", "abstract": "  Microlensing observations can be used for determining the shape of the Milky Way's halo. It can be shown that the data are best described with moderately flattened halo, 0.5 < q < 0.6. We discuss, by taking into account this result, the constraints on the baryonic mass-density parameter, Ω_B, and their implications on the value of the Hubble constant H_0, i.e. h. Our conclusion is that current data, in order to satisfy BBNS and Galaxy dynamics constraints, strongly suggest that h should take values within the lower part of the permissible range, h∼ 0.5. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9909/9909240v1.pdf"}
{"id": "astro-ph9911239", "abstract": "  The evolution of the magnetic field is investigated for isolated as well as binary neutron stars. The overall nature of the field evolution is seen to be similar for an initial crustal field and an expelled flux. The major uncertainties of the present models of field evolution and the directions in which further investigation are required are also discussed in detail. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9911/9911239v1.pdf"}
{"id": "astro-ph9912310", "abstract": "  We present a grid of evolutionary calculations for metal-poor low-mass stars for a variety of initial helium and metal abundances. The intention is mainly to provide a database for deriving directly stellar ages of halo and globular cluster stars for which basic stellar parameters are known, but the tracks can also be used for isochrone or luminosity function construction, since they extend to the tip of the red giant branch. Fitting formulae for age-luminosity relations are provided as well. The uncertainties of the evolutionary ages due to inherent shortcomings in the models and due to the unclear effectiveness of diffusion are discussed. A first application to field single stars is presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9912/9912310v2.pdf"}
{"id": "astro-ph9912442", "abstract": "  We present a new method to map the surface brightness of the accretion streams in AM Herculis systems from observed light curves. Extensive tests of the algorithm show that it reliably reproduces the intensity distribution of the stream for data with a signal-to-noise ratio >5. As a first application, we map the accretion stream emission of Civ lambda 1550 in the polar UZ Fornacis using HST FOS high state spectra. We find three main emission regions along the accretion stream: (1) On the ballistic part of the accretion stream, (2) on the magnetically funneled stream near the primary accretion spot, and (3) on the magnetically funneled stream at a position above the stagnation region. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9912/9912442v1.pdf"}
{"id": "chao-dyn9702007", "abstract": "  The spectral fluctuation properties of various two- and three-dimensional superconducting billiard systems are investigated by employing the correlation-hole method. It rests on the sensitivity of the spectral Fourier transform to long range correlations and is thus an alternative technique to study chaotic dynamics. First, we apply the method to the eigenfrequencies which are extracted from the measured resonances. Second, we analyze the unfolded raw spectra, including the shape of the resonances. The merit of the method lies in a clear separation of the statistics due to the positions and due to the shape of the resonances. However, we show that statistical fluctuations of the intensities of the resonances have a strong impact on the observable. Therefore, the visibility of the correlation hole is studied as a function of the number of independent statistical variables entering into the intensities. The visibility improves if independent spectra are superimposed. ", "pdf_url": "gs://arxiv-dataset/arxiv/chao-dyn/pdf/9702/9702007v1.pdf"}
{"id": "chao-dyn9910011", "abstract": "  Streamlines and distributions of nodal points are used as signatures of chaos in coherent electron transport through three types of billiards, Sinai, Bunimovich and rectangular. Numerical averaged distribution functions of nearest distances between nodal points are presented. We find the same form for the Sinai and Bunimovich billiards and suggest that there is a universal form that can be used as a signature of quantum chaos for electron transport in open billiards. The universal distribution function is found to be insensitive to the way avaraging is performed (over positions of leads, over an energy interval with a few conductance fluctuations, or both). The integrable rectangular billiard, on the other hand, displays nonuniversal distribution with a central peak related to partial order of nodal points for the case of symmetric attachment of leads. However cases with nonsymmetric leads tend to the universal form.   Also it is shown how nodal points in rectangular billiard can lead to \"channeling of quantum flows\" while disorder in nodal points in the Sinai billiard gives rise to unstable irregular behavior of the flow. ", "pdf_url": "gs://arxiv-dataset/arxiv/chao-dyn/pdf/9910/9910011v1.pdf"}
{"id": "cond-mat0002312", "abstract": "  The linear and nonlinear dynamical susceptibilities of a two level system are calculated as it undergoes a transition to a decoherent state. Analogously to the Glover-Tinkham-Ferrell sum rule of superconductivity, spectral weight in the linear susceptibility is continuously transferred from a finite frequency resonance to nearly zero frequency, corresponding to a broken symmetry in the thermodynamic limit. For this reason, the behavior of the present model (the Mermin model) differs significantly from the spin-boson model. The third order nonlinear susceptibility, corresponding to two-photon absorption, has an unexpected non-monotonic behavior as a function of the environmental coupling, reaching a maximum within the decoherent phase of the model. Both linear and nonlinear susceptibilities may be expressed in a universal form. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0002/0002312v1.pdf"}
{"id": "cond-mat0007035", "abstract": "  We study discrete solvent effects on the interaction of two parallel charged surfaces in ionic aqueous solution. These effects are taken into account by adding a bilinear non-local term to the free energy of Poisson-Boltzmann theory. We study numerically the density profile of ions between the two plates, and the resulting inter-plate pressure. At large plate separations the two plates are decoupled and the ion distribution can be characterized by an effective Poisson-Boltzmann charge that is smaller than the nominal charge. The pressure is thus reduced relative to Poisson-Boltzmann predictions. At plate separations below  2 nm the pressure is modified considerably, due to the solvent mediated short-range attraction between ions in the the system. For high surface charges this contribution can overcome the mean-field repulsion giving rise to a net attraction between the plates. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0007/0007035v1.pdf"}
{"id": "cond-mat0008192", "abstract": "  We extend the Microscopic Representation approach to the quantitative study of religious and folk stories: A story encrypting symbolically the creation is deconstructed into its simplest conceptual elements and their relationships. We single out a particular kind of relationship which we call \"diagonal (or transitive) link\": given 2 relations between the couples of elements AB and respectively BC, the \"diagonal link\" is the (composite) relation AC. We find that the diagonal links are strongly and systematically correlated with the events in the story that are considered crucial by the experts. We further compare the number of diagonal links in the symbolic creation story with a folk tale, which ostensibly narrates the same overt succession of events (but without pretensions of encrypting additional meanings). We find that the density of diagonal links per word in the folk story is lower by a factor of 2. We speculate that, as in other fields the simple transitive operations acting on elementary objects are at the core of the emergence and recognition of macroscopic meaning and novelty in complex systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0008/0008192v1.pdf"}
{"id": "cond-mat0010224", "abstract": "  A pair of concentric spheres separated by a small gap form a spherical Hele-Shaw cell. In this cell an interfacial instability arises when two immiscible fluids flow. We derive the equation of motion for the interface perturbation amplitudes, including both pressure and gravity drivings, using a mode coupling approach. Linear stability analysis shows that mode growth rates depend upon interface perimeter and gravitational force. Mode coupling analysis reveals the formation of fingering structures presenting a tendency toward finger tip-sharpening. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0010/0010224v2.pdf"}
{"id": "cond-mat0101115", "abstract": "  Molecular dynamics simulations of diluted ( 2.5 weight percent) aqueous solutions of two polyelectrolytes, namely sodium carboxy methyl cellulose (CMC) and sodium poly(acrylate) (PAA) have been performed. Water and counterions were taken into account explicitly. For CMC the substitution pattern and starting conformation is all-important. Two simulations of CMC oligomers resulted in different structures: One molecule takes a stretched conformation, while the second one keeps a globule-like, toroidal one. PAA is stretched during the whole simulation, with an average characteristic ratio of 8.3. On a local atomistic scale CMC and PAA have different hydrogen-bond properties. The COO- groups of PAA can only act as hydrogen bond acceptors, but due to the high negative charge density there are still more water molecules assembled around PAA than around CMC. There are 0.036 bonds/amu respectively 0.029 bonds/amu to water for the two CMC oligomers, but more than twice as many for PAA: 0.083 bonds/amu. Beside intermolecular hydrogen bonding, there is a significant amount of intramolecular H-bonding for CMC, which is influenced by the COO- groups, which act as strong H-acceptor. In contrast to hydroxy- and carboxylic groups, ether oxygens are hardly involved into hydrogen bonding. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0101/0101115v1.pdf"}
{"id": "cond-mat0103544", "abstract": "  We present the data on wealth and income distributions in the United Kingdom, as well as on the income distributions in the individual states of the USA. In all of these data, we find that the great majority of population is described by an exponential distribution, whereas the high-end tail follows a power law. The distributions are characterized by a dimensional scale analogous to temperature. The values of temperature are determined for the UK and the USA, as well as for the individual states of the USA. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0103/0103544v2.pdf"}
{"id": "cond-mat0105225", "abstract": "  We derive an expression for the static dielectric constant of the colloidal susp ensions based on the electrokinetic equations. The analysis assumes that the ions have the same diffusivity, and that the double layer is much thinner than the radius of curvature of the particles. It is shown that the dielectric increment of the double layer polarization mechanism is originated from the free energy stored in the salt concentration inhomogeniety. We also show that the dominant polarization charges in the theory are at the electrodes, rather than close to the particles. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0105/0105225v1.pdf"}
{"id": "cond-mat0107351", "abstract": "  We conduct molecular dynamics computer simulations of a system of Lennard-Jones particles, polydisperse in both size and mass, at a fixed density and temperature. We test for and quantify systematic changes in dynamical properties that result from polydispersity, by measuring the pair distribution function, diffusion coefficient, velocity autocorrelation function, and non-Gaussian parameter, as a function of the degree of polydispersity. Our results elucidate the interpretation of experimental studies of collective particle motion in colloids, and we discuss the implications of polydispersity for observations of dynamical heterogeneity, in both simulations of simple liquids and colloid experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0107/0107351v1.pdf"}
{"id": "cond-mat0108148", "abstract": "  We study energy relaxation in thermalized one-dimensional nonlinear arrays of the Fermi-Pasta-Ulam type. The ends of the thermalized systems are placed in contact with a zero-temperature reservoir via damping forces. Harmonic arrays relax by sequential phonon decay into the cold reservoir, the lower frequency modes relaxing first. The relaxation pathway for purely anharmonic arrays involves the degradation of higher-energy nonlinear modes into lower energy ones. The lowest energy modes are absorbed by the cold reservoir, but a small amount of energy is persistently left behind in the array in the form of almost stationary low-frequency localized modes. Arrays with interactions that contain both a harmonic and an anharmonic contribution exhibit behavior that involves the interplay of phonon modes and breather modes. At long times relaxation is extremely slow due to the spontaneous appearance and persistence of energetic high-frequency stationary breathers. Breather behavior is further ascertained by explicitly injecting a localized excitation into the thermalized array and observing the relaxation behavior. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0108/0108148v2.pdf"}
{"id": "cond-mat0110560", "abstract": "  Focusing on multifractal properties we investigate electric transport on random resistor diode networks at the phase transition between the non-percolating and the directed percolating phase. Building on first principles such as symmetries and relevance we derive a field theoretic Hamiltonian. Based on this Hamiltonian we determine the multifractal moments of the current distribution that are governed by a family of critical exponents {ψ_l }. We calculate the family {ψ_l } to two-loop order in a diagrammatic perturbation calculation augmented by renormalization group methods. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0110/0110560v1.pdf"}
{"id": "cond-mat0111245", "abstract": "  We present an analysis of the vibrational dynamics of metal vicinal surfaces using the embedded atom method to describe the interaction potential and both a real space Green's function method and a slab method to calculate the phonons.   We report two main general characteristics : a global shift of the surface vibrational density of states resulting from a softening of the force field. The latter is a direct result of the reduction of coordination for the different type of surface atoms; and an appearance of high frequency modes above the bulk band, resulting from a stiffening of the force field near the step atom. The latter is due to a rearrangement of the atomic positions during the relaxation of the surface atoms yielding a large shortening of the nearest neighbor distances near the step atoms. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0111/0111245v1.pdf"}
{"id": "cond-mat0204018", "abstract": "  Condensate of a charged boson fluid at non-integer dimensions between 2 and 3 is studied. Interaction between particles is assumed to be Coulombic, and Bogoliubov approximation is applied for a weak coupling regime. The condensate and the superfluid fraction at finite temperatures and at non-integer dimensions are calculated. The theoretical results are compared with the superfluid densities of superconducting films, which show a universal splitting behavior. The qualitative similarity between the charged boson fluid and the superconducting films gives a strong clue for the origin of the universality. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0204/0204018v1.pdf"}
{"id": "cond-mat0204313", "abstract": "  We use quantum Monte Carlo simulations to study the effect of disorder, in the form of a disordered chemical potential, on the phase diagram of the hard core bosonic Hubbard model in two dimensions. We find numerical evidence that in two dimensions, no matter how weak the disorder, it will always destroy the long range density wave order (checkerboard solid) present at half filling and strong nearest neighbor repulsion and replace it with a bose glass phase. We study the properties of this glassy phase including the superfluid density, energy gaps and the full Green's function. We also study the possibility of other localized phases at weak nearest neighbor repulsion, i.e. Anderson localization. We find that such a phase does not truly exist: The disorder must exceed a threshold before the bosons (at weak nn repulsion) are localized. The phase diagram for hard core bosons with disorder cannot be obtained easily from the soft core phase diagram discussed in the literature. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0204/0204313v1.pdf"}
{"id": "cond-mat0205271", "abstract": "  Both “phason” elastic constants have been measured from Monte Carlo simulations of a random-tiling icosahedral quasicrystal model with a Hamiltonian. The low-temperature limit approximates the “canonical-cell” tiling used to describe several real quasicrystals. The elastic constant K2 changes sign from positive to negative with decreasing temperature; in the “canonical-cell” limit, K2/K1 appears to approach -0.7, about the critical value for a phason-mode modulation instability. We compare to the experiments on i-AlPdMn and i-AlCuFe. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0205/0205271v1.pdf"}
{"id": "cond-mat0205608", "abstract": "  We investigate the stochastic resonance phenomena in the field-driven Ising model on small-world networks. The response of the magnetization to an oscillating magnetic field is examined by means of Monte Carlo dynamic simulations, with the rewiring probability varied. At any finite value of the rewiring probability, the system is found to undergo a dynamic phase transition at a finite temperature, giving rise to double resonance peaks. While the peak in the ferromagnetic phase grows with the rewiring probability, that in the paramagnetic phase tends to reduce, indicating opposite effects of the long-range interactions on the resonance in the two phases. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0205/0205608v1.pdf"}
{"id": "cond-mat0207096", "abstract": "  Ground-state properties of a double-large-dot sample connected to a reservoir via a single-mode point contact are investigated. When the interdot transmission is perfect and the dots controlled by the same dimensionless gate voltage, we find that for any finite backscattering from the barrier between the lead and the left dot, the average dot charge exhibits a Coulomb-staircase behavior with steps of size e/2 and the capacitance peak period is halved. The interdot electrostatic coupling here is weak. For strong tunneling between the left dot and the lead, we report a conspicuous intermediate phase in which the fractional plateaus get substantially altered by an increasing slope. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0207/0207096v2.pdf"}
{"id": "cond-mat0207144", "abstract": "  We study spin glasses on random lattices with finite connectivity. In the infinite connectivity limit they reduce to the Sherrington Kirkpatrick model. In this paper we investigate the expansion around the high connectivity limit. Within the replica symmetry breaking scheme at two steps, we compute the free energy at the first order in the expansion in inverse powers of the average connectivity (z), both for the fixed connectivity and for the fluctuating connectivity random lattices. It is well known that the coefficient of the 1/z correction for the free energy is divergent at low temperatures if computed in the one step approximation. We find that this annoying divergence becomes much smaller if computed in the framework of the more accurate two steps breaking. Comparing the temperature dependance of the coefficients of this divergence in the replica symmetric, one step and two steps replica symmetry breaking, we conclude that this divergence is an artefact due to the use of a finite number of steps of replica symmetry breaking. The 1/z expansion is well defined also in the zero temperature limit. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0207/0207144v1.pdf"}
{"id": "cond-mat0207322", "abstract": "  We study the growth of aligned domains in nematic liquid crystals. Results are obtained solving the Beris-Edwards equations of motion using the lattice Boltzmann approach. Spatial anisotropy in the domain growth is shown to be a consequence of the flow induced by the changing order parameter field (backflow). The generalization of the results to the growth of a cylindrical domain, which involves the dynamics of a defect ring, is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0207/0207322v2.pdf"}
{"id": "cond-mat0209150", "abstract": "  We report measurements of the low field structure of the magnetic vortex lattice in an untwinned YBCO single-crystal platelet. Measurements were carried out using a novel atomic beam magnetic resonance (ABMR) technique. For a 10.7 G field applied parallel to the c-axis of the sample, we find a triangular lattice with orientational order extending across the entire sample. We find the triangular lattice to be weakly distorted by the a-b anisotropy of the material and measure a distortion factor, f = 1.16. Model-experiment comparisons determine a penetration depth, lambda_ab = 140 (+-20) nm. The paper includes the first detailed description of the ABMR technique. We discuss both technical details of the experiment and the modeling used to interpret the measurements. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0209/0209150v2.pdf"}
{"id": "cond-mat0210487", "abstract": "  We develop a new variant of the recently introduced stochastic transfer-matrix DMRG which we call stochastic light-cone corner-transfer-matrix DMRG (LCTMRG). It is a numerical method to compute dynamic properties of one-dimensional stochastic processes. As suggested by its name, the LCTMRG is a modification of the corner-transfer-matrix DMRG (CTMRG), adjusted by an additional causality argument. As an example, two reaction-diffusion models, the diffusion-annihilation process and the branch-fusion process, are studied and compared to exact data and Monte-Carlo simulations to estimate the capability and accuracy of the new method. The number of possible Trotter steps of more than 10^5 shows a considerable improvement to the old stochastic TMRG algorithm. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0210/0210487v1.pdf"}
{"id": "cond-mat0211597", "abstract": "  We present results for the local density of states in the S and N layers of a SN multilayer, and the supercurrent, based on a Green's function formalism, as an extension of previous calculations on NS, SNS and SNSNS systems. The gap function is determined selfconsistently. Our systems are chosen to have a finite transverse width. We focus on phenomena which occur at so-called critical transverse widths, at which a new transverse mode is starting to contribute. It appears, that for an arbitrary width the Andreev approximation (AA), which takes into account only Andreev reflection at the SN interfaces, works well. We show that at a critical width the AA breaks down. An exact treatment is required, which considers also ordinary reflections. In addition, we study the influence of an interface barrier on the coupling between the S-layers. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0211/0211597v1.pdf"}
{"id": "cond-mat0302100", "abstract": "  We generalize to magnetic transition metals the approach proposed by Choi and Ihm for calculating the complex band structure of periodic systems, a key ingredient for future calculations of conductivity of an open quantum system within the Landauer-Buttiker theory. The method is implemented with ultrasoft pseudopotentials and plane wave basis set in a DFT-LSDA ab-initio scheme. As a first example, we present the complex band structure of bulk fcc Ni (which constitutes the tips of a Ni nanocontact) and monatomic Ni wire (the junction between two tips). Based on our results, we anticipate some features of the spin-dependent conductance in a Ni nanocontact. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0302/0302100v1.pdf"}
{"id": "cond-mat0305013", "abstract": "  Hydration of hydrophobic solutes in water is the cause of different phenomena, including the hydrophobic heat-capacity anomaly, which are not yet fully understood. Because of its topicality, there has recently been growing interest in the mechanism of hydrophobic aggregation, and in the physics on which it is based. In this study we use a simple yet powerful mixture model for water, an adapted two-state Muller-Lee-Graziano model, to describe the energy levels of water molecules as a function of their proximity to non-polar solute molecules. The model is shown to provide an appropriate description of many-body interactions between the hydrophobic solute particles. The solubility and aggregation of hydrophobic substances is studied by evaluating detailed Monte Carlo simulations in the vicinity of the first-order aggregation phase transition. A closed-loop coexistence curve is found, which is consistent with a mean-field calculation carried out for the same system. In addition, the destabilizing effect of a chaotropic substance in the solution is studied by suitable modification of the MLG model. These findings suggest that a simple model for the hydrophobic interaction may contain the primary physical processes involved in hydrophobic aggregation and in the chaotropic effect. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0305/0305013v1.pdf"}
{"id": "cond-mat0305384", "abstract": "  The study of the effects of the density variations on the vibrational dynamics in vitreous silica is presented. A detailed analysis of the dynamical structure factor, as well as of the current spectra, allows the identification of a flattened transverse branch which is highly sensitive to the density variations. The experimental variations on the intensity and position of the Boson Peak (BP) in v-SiO2 as a function of density are reproduced and interpreted as being due to the shift and disappearance of the latter band. The BP itself is found to correspond to the lower energy tail of the excess states due to the piling up of vibrational modes at energies corresponding to the flattening of the transverse branch. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0305/0305384v1.pdf"}
{"id": "cond-mat0305625", "abstract": "  We study the asymptotic macroscopic properties of the mixed majority-minority game, modeling a population in which two types of heterogeneous adaptive agents, namely “fundamentalists” driven by differentiation and “trend-followers” driven by imitation, interact. The presence of a fraction f of trend-followers is shown to induce (a) a significant loss of informational efficiency with respect to a pure minority game (in particular, an efficient, unpredictable phase exists only for f<1/2), and (b) a catastrophic increase of global fluctuations for f>1/2. We solve the model by means of an approximate static (replica) theory and by a direct dynamical (generating functional) technique. The two approaches coincide and match numerical results convincingly. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0305/0305625v2.pdf"}
{"id": "cond-mat0307344", "abstract": "  We numerically study the behavior of collapsing and exploding condensates using the parameters of the experiments by E.A. Donley et al. [Nature,   412, 295, (2001)]. Our studies are based on a full three-dimensional numerical solution of the Gross-Pitaevskii equation (GPE) including three body loss. We determine the three body loss rate from the number of remnant condensate atoms and collapse times and obtain only one possible value which fits with the experimental results. We then study the formation of jet atoms by interrupting the collapse and find very good agreement with the experiment. Furthermore we investigate the sensitivity of the jets to the initial conditions. According to our analysis the dynamics of the burst atoms is not described by the GPE with three body loss incorporated. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0307/0307344v1.pdf"}
{"id": "cond-mat0311413", "abstract": "  Ordered states on spheres require a minimum number of topological defects. For the case of crystalline order, triangular lattices must be interrupted by an array of at least 12 five-fold disclination defects, typically sitting at the vertices of an icosahedron. For R>>a, where R is the sphere radius and a the particle spacing, the energy associated with these defects is very large. This energy can be lowered, however, either by buckling, as appears to be the case for large viruses, or by introducing unusual finite length grain boundary scars. The latter have been observed recently for colloidal particles adsorbed onto water droplets in oil. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0311/0311413v1.pdf"}
{"id": "cond-mat0401267", "abstract": "  We present the results of Car-Parrinello (CP) simulations of water at ambient conditions and under pressure, using a rigid molecule approximation. Throughout our calculations, water molecules were maintained at a fixed intramolecular geometry corresponding to the average structure obtained in fully unconstrained simulations. This allows us to use larger time steps than those adopted in ordinary CP simulations of water, and thus to access longer time scales. In the absence of chemical reactions or dissociation effects, these calculations open the way to ab initio simulations of aqueous solutions that require timescales substantially longer than presently feasible (e.g. simulations of hydrophobic solvation). Our results show that structural properties and diffusion coefficients obtained with a rigid model are in better agreement with experiment than those determined with fully flexible simulations. Possible reasons responsible for this improved agreement are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0401/0401267v1.pdf"}
{"id": "cond-mat0401351", "abstract": "  Localization property in the disordered few-chain DNA systems with a long-range correlation is numerically investigated. We apply the chain system with the correlated disorder in the interchain and/or intrachain hoppings to the simple model of a double strand of DNA. Numerical results for the density of states and the Lyapunov exponent of the wave function in the two- or three-chain models are given. It is found that the correlation effect enhances the localization length (the inverse least nonnegative Lyapunov exponent) around the band center. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0401/0401351v2.pdf"}
{"id": "cond-mat0402327", "abstract": "  We show that lightly doped holes will be self-trapped in an antiferromagnetic spin background at low-temperatures, resulting in a spontaneous translational symmetry breaking. The underlying Mott physics is responsible for such novel self-localization of charge carriers. Interesting transport and dielectric properties are found as the consequences, including large doping-dependent thermopower and dielectric constant, low-temperature variable-range-hopping resistivity, as well as high-temperature strange-metal-like resistivity, which are consistent with experimental measurements in the high-T_c cuprates. Disorder and impurities only play a minor and assistant role here. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0402/0402327v2.pdf"}
{"id": "cond-mat0403194", "abstract": "  As a representative of a complex technological system, so-called wireless multihop ad hoc communication networks are discussed. They represent an infrastructure-less generalization of todays wireless cellular phone networks. Lacking a central control authority, the ad hoc nodes have to coordinate themselves such that the overall network performs in an optimal way. A performance indicator is the end-to-end throughput capacity.   Various models, generating differing ad hoc network structure via differing transmission power assignments, are constructed and characterized. They serve as input for a generic data traffic simulation as well as some semi-analytic estimations. The latter reveal that due to the most-critical-node effect the end-to-end throughput capacity sensitively depends on the underlying network structure, resulting in differing scaling laws with respect to network size. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0403/0403194v1.pdf"}
{"id": "cond-mat0403604", "abstract": "  We present here the preliminary results obtained for two experiments on randomly agitated granular assemblies using a novel way of shaking. First we discuss the transport properties of a 2D model system undergoing classical shaking that show the importance of large scale dynamics for this type of agitation and offer a local view of the microscopic motions of a grain. We then develop a new way of vibrating the system allowing for random accelerations smaller than gravity. Using this method we study the evolution of the free surface as well as results from a light scattering method for a 3D model system. The final aim of these experiments is to investigate the ideas of effective temperature on the one hand as a function of inherent states and on the other hand using fluctuation dissipation relations. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0403/0403604v1.pdf"}
{"id": "cond-mat0404054", "abstract": "  We study the phase synchronization of Kuramoto's oscillators in small parts of networks known as motifs. We first report on the system dynamics for the case of a scale-free network and show the existence of a non-trivial critical point. We compute the probability that network motifs synchronize, and find that the fitness for synchronization correlates well with motif's interconnectedness and structural complexity. Possible implications for present debates about network evolution in biological and other systems are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0404/0404054v1.pdf"}
{"id": "cond-mat0406680", "abstract": "  Thermodynamic properties of a tetramer ferro-ferro-antiferro-antiferromagnetic Ising-Heisenberg bond alternating chain are investigated by the use of an exact mapping transformation technique. Exact results for the magnetization, susceptibility and specific heat in the zero as well as nonzero magnetic field are presented and discussed in detail. The results obtained from the mapping are compared with the relevant experimental data of Cu(3-Clpy)_2(N_3)_2 (3-Clpy=3-Chloropyridine). ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0406/0406680v3.pdf"}
{"id": "cond-mat0409374", "abstract": "  The hysteresis curves of systems composed of small interacting magnetic particles, regularly placed on stacked layers, are obtained with Monte Carlo simulations. The remanence as a function of temperature, in interacting systems, presents a peak that separates two different magnetic states. At low temperatures, small values of remanence are a consequence of antiferromagnetic order due to the dipolar interaction. At higher values of temperature the increase of the component normal to the lattice plane is responsible for the small values of remanence. The effect of the number of layers, coordination number and distance between particles are investigated. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0409/0409374v1.pdf"}
{"id": "cond-mat0409768", "abstract": "  We present a Monte Carlo numerical investigation of the Hamiltonian Mean Field (HMF) model. We begin by discussing canonical Metropolis Monte Carlo calculations, in order to check the caloric curve of the HMF model and study finite size effects. In the second part of the paper, we present numerical simulations obtained by means of a modified Monte Carlo procedure with the aim to test the stability of those states at minimum temperature and zero magnetization (homogeneous Quasi Stationary States) which exist in the condensed phase of the model just below the critical point. For energy densities smaller than the limiting value U∼ 0.68, we find that these states are unstable, confirming a recent result on the Vlasov stability analysis applied to the HMF model. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0409/0409768v1.pdf"}
{"id": "cond-mat0409773", "abstract": "  Transportation infrastructure of a country is one of the most important indicators of its economic growth. Here we study the Airport Network of India (ANI), which represents India's domestic civil aviation infrastructure, as a complex network. We find that ANI, a network of domestic airports connected by air links, is a small-world network characterized by a truncated power-law degree distribution, and has a signature of hierarchy. We investigate ANI as a weighted network to explore its various properties and compare them with their topological counterparts. The traffic in ANI, as in the World-wide Airport Network (WAN), is found to be accumulated on interconnected groups of airports and is concentrated between large airports. In contrast to WAN, ANI is found to be having disassortative mixing which is offset by the traffic dynamics. The analysis indicates toward possible mechanism of formation of a national transportation network, which is different from that on a global scale. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0409/0409773v2.pdf"}
{"id": "cond-mat0412214", "abstract": "  In this work we investigate the energy gap between the ground state and the first excited state in a model of two single-mode Bose-Einstein condensates coupled via Josephson tunneling. The energy gap is never zero when the tunneling interaction is non-zero. The gap exhibits no local minimum below a threshold coupling which separates a delocalised phase from a self-trapping phase which occurs in the absence of the external potential. Above this threshold point one minimum occurs close to the Josephson regime, and a set of minima and maxima appear in the Fock regime. Analytic expressions for the position of these minima and maxima are obtained. The connection between these minima and maxima and the dynamics for the expectation value of the relative number of particles is analysed in detail. We find that the dynamics of the system changes as the coupling crosses these points. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0412/0412214v2.pdf"}
{"id": "cond-mat0412556", "abstract": "  We study triangular lattice spin-1/2 system with antiferromagnetic Heisenberg and ring exchanges using variational approach focusing on possible realization of spin liquid states. Trial spin liquid wave functions are obtained by Gutzwiller projection of fermionic mean field states and their energetics is compared against magnetically ordered trial states. We find that in a range of the ring exchange coupling upon destroying the antiferromagnetic order, the best such spin liquid state is essentially a Gutzwiller-projected Fermi sea state. We propose this spin liquid with spinon Fermi surface as a candidate for the nonmagnetic insulating phase observed in the organic compound κ-(ET)_2 Cu_2 (CN)_3, and describe some experimental consequences of this proposal. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0412/0412556v1.pdf"}
{"id": "cond-mat0501573", "abstract": "  The Landau-de Gennes free energy is used to study theoretically the interaction of parallel cylindrical colloidal particles trapped at a nematic-isotropic interface. We find that the effective interaction potential is non-monotonic. The corresponding force-distance curves exhibit jumps and hysteresis upon approach/separation due to the creation/annihilation of topological defects. Minimization results suggest a simple empirical pair potential for the effective colloid-colloid interaction at the interface. We propose that the interface-mediated interaction can play an important role in self-organization and clustering of colloidal particles at such interfaces. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0501/0501573v1.pdf"}
{"id": "cond-mat0503184", "abstract": "  We investigate the thermodynamics and signatures of a polariton condensate over a range of densities, using a model of microcavity polaritons with internal structure. We determine a phase diagram for this system including fluctuation corrections to the mean-field theory. At low densities the condensation temperature, T_c, behaves like that for point bosons. At higher densities, when T_c approaches the Rabi splitting, T_c deviates from the form for point bosons, and instead approaches the result of a BCS-like mean-field theory. This crossover occurs at densities much less than the Mott density. We show that current experiments are in a density range where the phase boundary is described by the BCS-like mean-field boundary. We investigate the influence of inhomogeneous broadening and detuning of excitons on the phase diagram. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0503/0503184v1.pdf"}
{"id": "cond-mat0504142", "abstract": "  The current-induced magnetization dynamics of a spin valve are studied using a macrospin (single domain) approximation and numerical solutions of a generalized Landau-Lifshitz-Gilbert equation. For the purpose of quantitative comparison with experiment [Kiselev et al. Nature 425, 380 (2003)], we calculate the resistance and microwave power as a function of current and external field including the effects of anisotropies, damping, spin-transfer torque, thermal fluctuations, spin-pumping, and incomplete absorption of transverse spin current. While many features of experiment appear in the simulations, there are two significant discrepancies: the current dependence of the precession frequency and the presence/absence of a microwave quiet magnetic phase with a distinct magnetoresistance signature. Comparison is made with micromagnetic simulations designed to model the same experiment. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0504/0504142v1.pdf"}
{"id": "cond-mat0510485", "abstract": "  We present a first-principles study of the unreconstructed (001) surfaces of the half-metallic ferromagnet NiMnSb. Both terminations (MnSb and Ni) are considered. We find that half-metallicity is lost at the surfaces. After a discussion of the geometric relaxations and the spin-polarized surface band structure, we focus on topography images which are expected to be found with spin-polarized scanning tunneling microscopy. For the MnSb-terminated surface we find that only the Sb atoms are visible, reflecting a geometric buckling caused by relaxations. For the Ni-terminated surface we find a strong contrast between the images of forward and reverse tip-sample-bias of 0.5 eV, as well as a stripe-like image for reverse bias. We interpret these findings in terms of highly directional surface states which are formed in the spin-down gap region. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0510/0510485v1.pdf"}
{"id": "cond-mat0511221", "abstract": "  The combination of density functional theory with other approaches to the many-electron problem through the separation of the electron-electron interaction into a short-range and a long-range contribution is a promising method, which is raising more and more interest in recent years. In this work some properties of the corresponding correlation energy functionals are derived by studying the electron-electron coalescence condition for a modified (long-range-only) interaction. A general relation for the on-top (zero electron-electron distance) pair density is derived, and its usefulness is discussed with some examples. For the special case of the uniform electron gas, a simple parameterization of the on-top pair density for a long-range only interaction is presented and supported by calculations within the “extended Overhauser model”. The results of this work can be used to build self-interaction corrected short-range correlation energy functionals. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0511/0511221v2.pdf"}
{"id": "cond-mat0511287", "abstract": "  The effect of electron-phonon interactions in the conductance through metallic atomic wires is theoretically analyzed. The proposed model allows to consider an atomic size region electrically and mechanically coupled to bulk electrodes. We show that under rather general conditions the features due to electron-phonon coupling are described by universal functions of the system transmission coefficients. It is predicted that the reduction of the conductance due to electron-phonon coupling which is observed close to perfect transmission should evolve into an enhancement at low transmission. This crossover can be understood in a transparent way as arising from the competition between elastic and inelastic processes. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0511/0511287v1.pdf"}
{"id": "cond-mat0604522", "abstract": "  We present a general derivation of the electron spin noise power spectrum in alkali gases as measured by optical Faraday rotation, which applies to both classical gases at high temperatures as well as ultracold quantum gases. We show that the spin-noise power spectrum is determined by an electron spin-spin correlation function, and we find that measurements of the spin-noise power spectra for a classical gas of ^41K atoms are in good agreement with the predicted values. Experimental and theoretical spin noise spectra are directly and quantitatively compared in both longitudinal and transverse magnetic fields up to the high magnetic field regime (where Zeeman energies exceed the intrinsic hyperfine energy splitting of the ^41K ground state). ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0604/0604522v1.pdf"}
{"id": "cond-mat0605168", "abstract": "  Understanding charging mechanisms and charge retention dynamics of nanocrystal memory devices is important in optimization of device design. Capacitance spectroscopy on PECVD grown germanium nanocrystals embedded in a silicon oxide matrix was performed. Dynamic measurements of discharge dynamics are carried out. Charge decay is modelled by assuming storage of carriers in the ground states of nanocrystals and that the decay is dominated by direct tunnelling. Discharge rates are calculated using the theoretical model for different nanocrystal sizes and densities and are compared with experimental data. Experimental results agree well with the proposed model and suggest that charge is indeed stored in the quantized energy levels of the nanocrystals. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0605/0605168v2.pdf"}
{"id": "cond-mat0606543", "abstract": "  We present a zero-temperature quantum Monte Carlo calculation of liquid ^4He immersed in an array of confining potentials. These external potentials are centered in the lattice sites of a fcc solid geometry and, by modifying their well depth and range, the system evolves from a liquid phase towards a progressively localized system which mimics a solid phase. The superfluid density decreases with increasing order, reaching a value ρ_ s/ρ = 0.079(16) when the Lindemann's ratio of the model equals the experimental value for solid ^4He. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0606/0606543v1.pdf"}
{"id": "cond-mat0606674", "abstract": "  Conventional wisdom presumes that low-coordinated crystal ground states require directional interactions. Using our recently introduced optimization procedure to achieve self-assembly of targeted structures (Phys. Rev. Lett. 95, 228301 (2005), Phys. Rev. E 73, 011406 (2006)), we present an isotropic pair potential V(r) for a three-dimensional many-particle system whose classical ground state is the low-coordinated simple cubic (SC) lattice. This result is part of an ongoing pursuit by the authors to develop analytical and computational tools to solve statistical-mechanical inverse problems for the purpose of achieving targeted self-assembly. The purpose of these methods is to design interparticle interactions that cause self-assembly of technologically important target structures for applications in photonics, catalysis, separation, sensors and electronics. We also show that standard approximate integral-equation theories of the liquid state that utilize pair correlation function information cannot be used in the reverse mode to predict the correct simple cubic potential. We report in passing optimized isotropic potentials that yield the body-centered cubic and simple hexagonal lattices, which provide other examples of non-close-packed structures that can be assembled using isotropic pair interactions. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0606/0606674v1.pdf"}
{"id": "cond-mat0607725", "abstract": "  Charge centers in ionic crystals provide a channel for elementary interaction between electromagnetic radiation and the lattice. We calculate the electronic ground state energies which are needed to create a charge center – namely a F- and a H-center. In well agreement with common understanding the F-center results in being accompanied by a small lattice distortion whereas the H-center is accompanied by a very large lattice deformation. Opposite to the common understanding the additional positive charge in the charge center results rather to be localized on a F_4^3- complex than on a F_2^--complex. From the ground states of the charge centers we derive binding energies, diffusion barriers and agglomeration energies for M-center formation. These microscopic quantities are of fundamental interest to understand the dynamic processes which are initiated if the crystals interact with extreme intense deep ultra violet radiation. We further derive the equilibrium concentrations of charge centers in grown crystals. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0607/0607725v1.pdf"}
{"id": "cond-mat0608247", "abstract": "  The atom fluctuations statistics of an ideal, mesoscopic, Bose-Einstein condensate is investigated from several different perspectives. By generalizing the grand canonical analysis (applied to the canonical ensemble problem), we obtain a self-consistent equation for the mean condensate particle number that coincides with the microscopic result calculated from the laser master equation approach. For the case of a harmonic trap, we obtain an analytic expression for the condensate particle number that is very accurate at all temperatures, when compared with numerical canonical ensemble results. Applying a similar generalized grand canonical treatment to the variance, we obtain an accurate result only below the critical temperature. Analytic results are found for all higher moments of the fluctuation distribution by employing the stochastic path integral formalism, with excellent accuracy. We further discuss a hybrid treatment, which weds the master equation/stochastic path integral analysis with the results obtained based on canonical ensemble quasiparticle formalism [V. V. Kocharovsky et al., Phys. Rev. A 61, 053606 (2000)], producing essentially perfect agreement with numerical simulation at all temperatures. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0608/0608247v1.pdf"}
{"id": "cond-mat0610112", "abstract": "  The kinetics of a granular planar rotator with a fixed center undergoing inelastic collisions with bath particles is analyzed both numerically and analytically by means of the Boltzmann equation. The angular velocity distribution evolves from quasi-gaussian in the Brownian limit to an algebraic decay in the limit of an infinitely light particle. In addition, we compare this model with a planar rotator with a free center. We propose experimental tests that might confirm the predicted behaviors. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0610/0610112v1.pdf"}
{"id": "cond-mat0610267", "abstract": "  Magnetism in bare uncapped gold nano-clusters is explored from a density functional theory perspective with scalar relativistic effects included via the pseudo-potential. The computed electronic structures of various nano-clusters reveal that permanent size-dependent spin-polarization appears without geometry relaxation for bare clusters even though bulk gold is diamagnetic. The polarized ground states for clusters are favorable due to the hybridization of the s and d orbitals, and bare octahedral clusters are expected to be magnetic for cluster sizes of approximately 38 atoms and larger. Much larger clusters will be diamagnetic when the surface-to-volume ratio is small and the core diamagnetism prevails. Moderate changes in the inter-atomic distances and cluster geometry are shown not to alter this conclusion. Contrary to LDA and EAM predictions, GGA and hybrid geometry optimizations reveal increased inter-atomic bond distances in bare gold clusters relative to the bulk lattice values. This expansion enhances the preexisting spin polarization. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0610/0610267v1.pdf"}
{"id": "cond-mat0610644", "abstract": "  We show that the phase of a condensate in a finite temperature gas spreads linearly in time at long times rather than in a diffusive way. This result is supported by classical field simulations, and analytical calculations which are generalized to the quantum case under the assumption of quantum ergodicity in the system. This super-diffusive behavior is intimately related to conservation of energy during the free evolution of the system and to fluctuations of energy in the prepared initial state. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0610/0610644v3.pdf"}
{"id": "cond-mat0701276", "abstract": "  We report size-dependent melting of spherical copper nanoparticles embedded into silica matrix. Based on the temperature dependence of the surface plasmon resonance energy and its width we observe two distinct melting regimes. For particles smaller than 20 nm the absorption spectrum changes monotonically with the temperature, and this allows us to assume the gradual solid-liquid phase transition (melting) of the nanoparticles or existence of superheated solid nanoparticles. In contrast, for nanoparticles larger than 20 nm, we observe a jump-like increase of the bandwidth and non-monotonic dependence of surface plasmon energy at the temperatures below the bulk melting point. This indicates that the melting of large nanoparticles is a first-order phase transition similar to the melting of bulk copper. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0701/0701276v1.pdf"}
{"id": "cond-mat0701389", "abstract": "  We present a model study of ferromagnetic films consisting of free Bloch electrons coupled to localized moments (Kondo lattice films). By mapping the local interaction onto an effective Heisenberg Hamiltonian we obtain temperature and carrier density dependent exchange integrals mediating the interaction between local moments via the conduction electrons. The non-perturbative approach recovers analytically the weak-coupling RKKY interaction and yields convincing numerical results in the strong coupling (double exchange) regime. The Curie temperature is calculated for various coupling strengths, band fillings, and numbers of layers. The results are compared with total energy calculations. We discuss the influence of charge transfer between film layers and of anisotropy on the Curie temperature. The model we investigate is considered relevant for the understanding of the basic magnetic properties of manganites, diluted magnetic semiconductors, and rare earth substances as, e.g., Gadolinium. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0701/0701389v1.pdf"}
{"id": "cond-mat9412105", "abstract": "  It is shown how a recent method to systematically extrapolate and resum the loop expansion for nonlinear sigma-models is related to solutions of the renormalization group equation. This relation is used to generalize the explicit equations of state obtained previously to models which display crossover phenomena. As an example we discuss Wegner's localization model and consider the crossover from symplectic to unitary symmetry. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9412/9412105v1.pdf"}
{"id": "cond-mat9602055", "abstract": "  We have carried out extensive series studies, at T=0 and at high temperatures, of 2-chain and 3-chain spin-half ladder systems with antiferromagnetic intrachain and both antiferromagnetic and ferromagnetic interchain couplings. Our results confirm the existence of a gap in the 2-chain Heisenberg ladders for all non-zero values of the interchain couplings. Complete dispersion relations for the spin-wave excitations are computed. For 3-chain systems, our results are consistent with a gapless spectrum. We also calculate the uniform magnetic susceptibility and specific heat as a function of temperature. We find that as T→ 0, for the 2-chain system the uniform susceptibility goes rapidly to zero, whereas for the 3-chain system it approaches a finite value. These results are compared in detail with previous studies of finite systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9602/9602055v1.pdf"}
{"id": "cond-mat9609032", "abstract": "  The normal modes of a commensurate monolayer solid may be damped by mixing with elastic waves of the substrate. This was shown by B. Hall et al., Phys. Rev. B 32, 4932 (1985), for perpendicular adsorbate vibrations in the presence of an isotropic elastic medium. That work is generalized with an elastic continuum theory of the response of modes of either parallel or perpendicular polarization for a spherical adsorbate on a hexagonal substrate. The results are applied to the discussion of computer simulations and inelastic atomic scattering experiments for adsorbates on graphite. The extreme anisotropy of the elastic behavior of the graphite leads to quite different wave vector dependence of the damping for modes polarized perpendicular and parallel to the substrate. A phenomenological extension of the elasticity theory of the graphite to include bond-bending energies improves the description of substrate modes with strong anomalous dispersion and enables a semi-quantitative account of observed avoided crossings of the adlayer perpendicular vibration mode and the substrate Rayleigh mode. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9609/9609032v1.pdf"}
{"id": "cond-mat9609264", "abstract": "  We analyse the properties of a very simple “balls-in-boxes” model which can exhibit a phase transition between a fluid and a condensed phase, similar to behaviour encountered in models of random geometries in one, two and four dimensions. This model can be viewed as a generalisation of the backgammon model introduced by Ritort as an example of glassy behaviour without disorder. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9609/9609264v2.pdf"}
{"id": "cond-mat9701158", "abstract": "  The metal-insulator transition in one dimensional fermionic systems with long-range interaction is investigated. We have focused on an excitation spectrum by the exact diagonalization technique in sectors with different momentum quantum numbers. At rational fillings, we have demonstrated gap opening transitions from the Tomonaga-Luttinger liquid to the Mott insulator associated with a discrete symmetry breaking by changing the interaction strength. Finite interaction range is crucial to have the Mott transition at a rational filling away from the half filling. It is consistent with the strong coupling picture where the Mott gap exists at any rational fillings with sufficiently strong interaction. The critical regions as a quantum phase transition are also investigated numerically. Non-analytic behavior of the Mott gap is the characteristic in the weak coupling. It is of the order of the interaction in the strong coupling. It implies that the metal-insulator transition of the model is of the infinite order as a quantum phase transition at zero temperature. Fractal nature of the ground state phase diagram is also revealed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9701/9701158v1.pdf"}
{"id": "cond-mat9704016", "abstract": "  We present the results of extensive Monte Carlo simulations of Ising models with algebraically decaying ferromagnetic interactions in the regime where classical critical behavior is expected for these systems. We corroborate the values for the exponents predicted by renormalization theory for systems in one, two, and three dimensions and accurately observe the predicted logarithmic corrections at the upper critical dimension. We give both theoretical and numerical evidence that above the upper critical dimension the decay of the critical spin-spin correlation function in finite systems consists of two different regimes. For one-dimensional systems our estimates for the critical couplings are more than two orders of magnitude more accurate than existing estimates. In two and three dimensions we give, to our knowledge, the first results for the critical couplings. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9704/9704016v2.pdf"}
{"id": "cond-mat9801282", "abstract": "  Within the framework of an exactly solvable model, which takes into account the interaction of fluctuating modes with equal and opposite momenta, we consider phase diagrams in systems with coupled scalar order parameters. We show that, in agreement with the renormalization group theory, the fluctuation interaction can split the continuous disorder-order transition into two phase transitions of the first order. Moreover, the transition may occur into the anomalous, from the mean field theory point of view phase. The effect disappears when the fluctuation interaction is suppressed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9801/9801282v1.pdf"}
{"id": "cond-mat9802028", "abstract": "  The Bak-Sneppen model is shown to fall into a different universality class with the introduction of a preferred direction, mirroring the situation in spin systems. This is first demonstrated by numerical simulations and subsequently confirmed by analysis of the multi-trait version of the model, which admits exact solutions in the extremes of zero and maximal anisotropy. For intermediate anisotropies, we show that the spatiotemporal evolution of the avalanche has a power law “tail” which passes through the system for any non-zero anisotropy but remains fixed for the isotropic case, thus explaining the crossover in behaviour. Finally, we identify the maximally anisotropic model which is more tractable and yet more generally applicable than the isotropic system. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9802/9802028v2.pdf"}
{"id": "cond-mat9803128", "abstract": "  We derive the effective low-energy theory for single-wall carbon nanotubes including the Coulomb interactions among electrons. The generic model found here consists of two spin-1/2 fermion chains which are coupled by the interaction. We analyze the theory using bosonization, renormalization-group techniques, and Majorana refermionization. Several experimentally relevant consequences of the breakdown of Fermi liquid theory observed here are discussed in detail, e.g., magnetic instabilities, anomalous conductance laws, and impurity screening profiles. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9803/9803128v1.pdf"}
{"id": "cond-mat9804322", "abstract": "  The angular and frequency correlation functions of the transmission coefficient for light propagation through a strongly scattering amplifying medium are considered. It is found that just as in the case of an elastic scattering medium the correlation function consists of three terms. However, the structure of the terms is rather different. Angular correlation has a power-law decay and exhibits oscillations. There is no \"memory effect\" as in the case of an elastic medium. Interaction between diffusion modes is strongly enhanced near the lasing threshold. Frequency correlation scale decreases close to the lasing threshold.   We also consider time correlations of the transmission in the case of nonstationary inhomogeneities. We find short- and long-range time correlations. The scale of the short-range correlation decreases, while the long-range correlation scale becomes infinite near the threshold. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9804/9804322v1.pdf"}
{"id": "cond-mat9809039", "abstract": "  The microscopic approach to the description of the phase behaviour and critical phenomena in binary fluid mixtures is proposed. It is based on the method of collective variables with a reference system. The physical nature of the order parameter in a binary mixture is discussed. The basic density measure (Ginsburg-Landau-Wilson Hamiltonian) is obtained in the collective variable phase space which contains the variable connected with the order parameter of the system. It is shown that the problem can be reduced to the 3D Ising model in an external field. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9809/9809039v1.pdf"}
{"id": "cond-mat9809260", "abstract": "  Electronic and magnetic properties of ribbon-shaped nanographite systems with zigzag and armchair edges in a magnetic field are investigated by using a tight binding model. One of the most remarkable features of these systems is the appearance of edge states, strongly localized near zigzag edges. The edge state in magnetic field, generating a rational fraction of the magnetic flux (ϕ= p/q) in each hexagonal plaquette of the graphite plane, behaves like a zero-field edge state with q internal degrees of freedom. The orbital diamagnetic susceptibility strongly depends on the edge shapes. The reason is found in the analysis of the ring currents, which are very sensitive to the lattice topology near the edge. Moreover, the orbital diamagnetic susceptibility is scaled as a function of the temperature, Fermi energy and ribbon width. Because the edge states lead to a sharp peak in the density of states at the Fermi level, the graphite ribbons with zigzag edges show Curie-like temperature dependence of the Pauli paramagnetic susceptibility. Hence, it is shown that the crossover from high-temperature diamagnetic to low-temperature paramagnetic behavior of the magnetic susceptibility of nanographite ribbons with zigzag edges. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9809/9809260v2.pdf"}
{"id": "cond-mat9811155", "abstract": "  We review here a novel circuit theory of superconductivity. The existed circuit theory of Andreev reflection has been revised to account for decoherence between electrons and holes and twofold nature of the distribution function. The description of arbitrary connectors has been elaborated. In this way one can cope with the most of the factors that limited applicability of the old circuit theory. We give a simple example and discuss numerical implementation of the theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9811/9811155v1.pdf"}
{"id": "cond-mat9901127", "abstract": "  A tight binding parameterization of the band structure, along with a mean field treatment of Hund, electron-electron, and electron-lattice couplings, is used to obtain the full optical conductivity tensor of LaMnO_3 as a function of temperature. We predict striking changes with temperature in the functional form and magnitude of the optical absorption. Comparison of our results to data will determine the Hund, electron-lattice, and electron-electron interactions. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9901/9901127v2.pdf"}
{"id": "cond-mat9904356", "abstract": "  We study finite-size effects in the self-organized critical forest-fire model by numerically evaluating the tree density and the fire size distribution. The results show that this model does not display the finite-size scaling seen in conventional critical systems. Rather, the system is composed of relatively homogeneous patches of different tree densities, leading to two qualitatively different types of fires: those that span an entire patch and those that don't. As the system size becomes smaller, the system contains less patches, and finally becomes homogeneous, with large density fluctuations in time. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9904/9904356v2.pdf"}
{"id": "cond-mat9908077", "abstract": "  Energy barriers for different moves of a single Rh adatom in the vicinity of steps on Rh(111) surface are studied with molecular statics. Interatomic interactions are modeled by the semi-empirical many-body Rosato-Guillope-Legrand potential. We calculate systematically barriers for the descent at straight steps, steps with the kink and small islands as well as barriers for diffusion along the step edges. The descent is more probable on steps with a 111 microfacet and near kinks. Diffusion along a step with a 100 microfacet is faster than along a step with a 111 microfacet. We also calculate barriers for diffusion on several surfaces vicinal to Rh(111). ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9908/9908077v2.pdf"}
{"id": "cond-mat9909224", "abstract": "  The magnetic properties of the t-t' Hubbard Model in the two dimensional square lattice are studied within an unrestricted Hartree-Fock approximation in real space. The interplay between antiferromagnetism, ferromagnetism, phase separation and inhomogeneous magnetic textures is studied. It is shown that, at sufficiently large values of t'/t, a rich fenomenology is to be expected between the antiferromagnetic phase at half filling and the ferromagnetic phase a lower fillings. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9909/9909224v1.pdf"}
{"id": "cond-mat9909355", "abstract": "  A precursor effect on the Fermi surface in the two-dimensional Hubbard model at finite temperatures near the antiferromagnetic instability is studied using three different itinerant approaches: the second order perturbation theory, the paramagnon theory (PT), and the two-particle self-consistent (TPSC) approach. In general, at finite temperature, the Fermi surface of the interacting electron systems is not sharply defined due to the broadening effects of the self-energy. In order to take account of those effects we consider the single-particle spectral function A( k,0) at the Fermi level, to describe the counterpart of the Fermi surface at T=0. We find that the Fermi surface is destroyed close to the pseudogap regime due to the spin-fluctuation effects in both PT and TPSC approaches. Moreover, the top of the effective valence band is located around k=(π/2,π/2) in agreement with earlier investigations on the single-hole motion in the antiferromagnetic background. A crossover behavior from the Fermi-liquid regime to the pseudogap regime is observed in the electron concentration dependence of the spectral function and the self-energy. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9909/9909355v2.pdf"}
{"id": "cond-mat9910009", "abstract": "  The categorization ability of fully connected neural network models, with either discrete or continuous Q-state units, is studied in this work in replica symmetric mean-field theory. Hierarchically correlated multi-state patterns in a two level structure of ancestors and descendents (examples) are embedded in the network and the categorization task consists in recognizing the ancestors when the network is trained exclusively with their descendents. Explicit results for the dependence of the equilibrium properties of a Q=3-state model and a Q=∞-state model are obtained in the form of phase diagrams and categorization curves. A strong improvement of the categorization ability is found when the network is trained with examples of low activity. The categorization ability is found to be robust to finite threshold and synaptic noise. The Almeida-Thouless lines that limit the validity of the replica-symmetric results, are also obtained. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9910/9910009v1.pdf"}
{"id": "cond-mat9912103", "abstract": "  Using a simple cellular automaton with stochastic rules we show the possible emergence of thermally activated avalanches (power law distributed) in type-II superconductors. Scaling relations between the exponents characterizing these distributions and those obtained from field driven experiments are derived and proved through simulations. It is also shown that the conditions for the appearance of these avalanches are independent of the pinning mechanism. The relevance of our simulations for recently reported experimental results is also outlined. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9912/9912103v2.pdf"}
{"id": "cs0305057", "abstract": "  The Persint program is designed for the three-dimensional representation of objects and for the interfacing and access to a variety of independent applications, in a fully interactive way. Facilities are provided for the spatial navigation and the definition of the visualization properties, in order to interactively set the viewing and viewed points, and to obtain the desired perspective. In parallel, applications may be launched through the use of dedicated interfaces, such as the interactive reconstruction and display of physics events. Recent developments have focalized on the interfacing to the XML ATLAS General Detector Description AGDD, making it a widely used tool for XML developers. The graphics capabilities of this program were exploited in the context of the ATLAS 2002 Muon Testbeam where it was used as an online event display, integrated in the online software framework and participating in the commissioning and debug of the detector system. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0305/0305057v1.pdf"}
{"id": "cs0405006", "abstract": "  We describe in this paper a new method for building an efficient algorithm for scheduling jobs in a cluster. Jobs are considered as parallel tasks (PT) which can be scheduled on any number of processors. The main feature is to consider two criteria that are optimized together. These criteria are the makespan and the weighted minimal average completion time (minsum). They are chosen for their complementarity, to be able to represent both user-oriented objectives and system administrator objectives. We propose an algorithm based on a batch policy with increasing batch sizes, with a smart selection of jobs in each batch. This algorithm is assessed by intensive simulation results, compared to a new lower bound (obtained by a relaxation of ILP) of the optimal schedules for both criteria separately. It is currently implemented in an actual real-size cluster platform. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0405/0405006v3.pdf"}
{"id": "cs0702172", "abstract": "  A numerical model is constructed for modelling macroscale damping effects induced by the first order martensite phase transformations in a shape memory alloy rod. The model is constructed on the basis of the modified Landau-Ginzburg theory that couples nonlinear mechanical and thermal fields. The free energy function for the model is constructed as a double well function at low temperature, such that the external energy can be absorbed during the phase transformation and converted into thermal form. The Chebyshev spectral methods are employed together with backward differentiation for the numerical analysis of the problem. Computational experiments performed for different vibration energies demonstrate the importance of taking into account damping effects induced by phase transformations. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0702/0702172v1.pdf"}
{"id": "gr-qc0008005", "abstract": "  Cosmological nucleosynthesis calculations imply that there should be both non-baryonic and baryonic dark matter. Recent data suggest that some of the non-baryonic dark matter must be \"hot\" (i.e. massive neutrinos) and there may also be evidence for \"cold\" dark matter (i.e. WIMPs). If the baryonic dark matter resides in galactic halos, it is likely to be in the form of compact objects (i.e. MACHOs) and these would probably be the remnants of a first generation of pregalactic or protogalactic Population III stars. Many candidates have been proposed - brown dwarfs, red dwarfs, white dwarfs or black holes - and at various times each of these has been in vogue. We review the many types of observations which can be used to constrain or exclude both baryonic and non-baryonic dark matter candidates. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0008/0008005v1.pdf"}
{"id": "gr-qc0304085", "abstract": "  Black strings, one class of higher dimensional analogues of black holes, were shown to be unstable to long wavelength perturbations by Gregory and Laflamme in 1992, via a linear analysis. We revisit the problem through numerical solution of the full equations of motion, and focus on trying to determine the end-state of a perturbed, unstable black string. Our preliminary results show that such a spacetime tends towards a solution resembling a sequence of spherical black holes connected by thin black strings, at least at intermediate times. However, our code fails then, primarily due to large gradients that develop in metric functions, as the coordinate system we use is not well adapted to the nature of the unfolding solution. We are thus unable to determine how close the solution we see is to the final end-state, though we do observe rich dynamical behavior of the system in the intermediate stages. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0304/0304085v1.pdf"}
{"id": "gr-qc0401114", "abstract": "  To every axi-symmetric isolated horizon we associate two sets of numbers, M_n and J_n with n = 0, 1, 2, ..., representing its mass and angular momentum multipoles. They provide a diffeomorphism invariant characterization of the horizon geometry. Physically, they can be thought of as the `source multipoles' of black holes in equilibrium. These structures have a variety of potential applications ranging from equations of motion of black holes and numerical relativity to quantum gravity. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0401/0401114v2.pdf"}
{"id": "gr-qc0503094", "abstract": "  Quantum non-cloning theorem and a thought experiment are discussed for charged black holes whose global structure exhibits an event and a Cauchy horizon. We take Reissner-Norström black holes and two-dimensional dilaton black holes as concrete examples. The results show that the quantum non-cloning theorem and the black hole complementarity are far from consistent inside the inner horizon. The relevance of this work to non-local measurements is briefly discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0503/0503094v2.pdf"}
{"id": "gr-qc0512127", "abstract": "  Astrophysical tests of Planck-suppressed Lorentz violations had been extensively studied in recent years and very stringent constraints have been obtained within the framework of effective field theory. There are however still some unresolved theoretical issues, in particular regarding the so called \"naturalness problem\" - which arises when postulating that Planck-suppressed Lorentz violations arise only from operators with mass dimension greater than four in the Lagrangian. In the work presented here we shall try to address this problem by looking at a condensed-matter analogue of the Lorentz violations considered in quantum gravity phenomenology. Specifically, we investigate the class of two-component BECs subject to laser-induced transitions between the two components, and we show that this model is an example for Lorentz invariance violation due to ultraviolet physics. We shall show that such a model can be considered to be an explicit example high-energy Lorentz violations where the “naturalness problem” does not arise. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0512/0512127v1.pdf"}
{"id": "gr-qc9609013", "abstract": "  A characteristic spectrum of relic gravitational radiation is produced by a period of “stringy inflation\" in the early universe. This spectrum is unusual, because the energy-density rises rapidly with frequency. We show that correlation experiments with the two gravitational wave detectors being built for the Laser Interferometric Gravitational Observatory (LIGO) could detect this relic radiation, for certain ranges of the parameters that characterize the underlying string cosmology model. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/9609/9609013v1.pdf"}
{"id": "gr-qc9903036", "abstract": "  In this paper the second Lyapunov method is used to study the stability of the de Sitter phase of cosmic expansion when the source of the gravitational field is a viscous fluid. Different inflationary scenarios related with reheating and decay of mini-blackholes into radiation are investigated using an effective fluid described by time–varying thermodynamical quantities. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/9903/9903036v2.pdf"}
{"id": "hep-ex0011025", "abstract": "  The first neutrino observations from the Sudbury Neutrino Observatory are presented from preliminary analyses. Based on energy, direction and location, the data in the region of interest appear to be dominated by 8B solar neutrinos, detected by the charged current reaction on deuterium and elastic scattering from electrons, with very little background. Measurements of radioactive backgrounds indicate that the measurement of all active neutrino types via the neutral current reaction on deuterium will be possible with small systematic uncertainties. Quantitative results for the fluxes observed with these reactions will be provided when further calibrations have been completed. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ex/pdf/0011/0011025v1.pdf"}
{"id": "hep-ex0206065", "abstract": "  We discuss recent achievements in light scalar mesons spectroscopy through amplitude analysis of charm particle decay and its consequences. The high statistics clean samples of charmed mesons, in addition to it's definite J^P and mass, is turning these decays into a new important environment to study light meson physics. We give special attention to the scalar sector favored by a high coupling to charm. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ex/pdf/0206/0206065v1.pdf"}
{"id": "hep-ex9905006", "abstract": "  The development of gaseous detectors has been exciting again since the appearance of a MicroStrip Gas Chamber(MSGC) in 1988, which is made using a micro-electronics technology. These days lots of variations of the advanced gaseous detectors are being intensively studied in the world.   We have developed the two-dimensional MSGC having a 10 cm square detection area and the ultra fast readout system for a real time X-ray imaging. The MSGC was made using Multi-Chip Module (MCM) technology, and has a very thin substrate of 17 μm, lots of thin anodes and back strips both with 200 μm pitches. This enables us to get fast digital X-ray images with recording both the timing and an energy of each X-ray photon. In addition, an intermediate gas multiplier has been realized using a capillary plate having a conductive surface of a capillary. The MSGC combined with the conductive capillary plate can be steadily operated with a high gain under intense irradiation. Here we also report new approaches of X-ray crystal structure analyses using timing information obtained by the MSGC. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ex/pdf/9905/9905006v2.pdf"}
{"id": "hep-ph0001150", "abstract": "  We study chiral expansion at m_ρ-scale in framework of chiral constituent quark model. The lowest vector meson resonsances are treated as composited fields of constituent quarks. We illustrate that, at energy scale of ρ-meson mass, the chiral expansion expansion converges slowly. Therefore, it is possible to construct a well-defined chiral effective field theory at this energy scale, but high order correction of chiral expansion must be included simultanously. The one-loop correction of pseudoscalar mesons is also studied systematically. The unitarity of the model is examined and Breit-Wigner formula for ρ-meson is obtained. The prediction on on-shell ρ→ππ and ρ→ e^+e^- decays agree with data very well. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0001/0001150v2.pdf"}
{"id": "hep-ph0010287", "abstract": "  The construction of low-energy effective actions in QED for several types of external conditions is reviewed. Emphasis is put on the application of these effective actions to a variety of physical effects which represent a manifestation of vacuum polarization. Soft-photon interactions with external electromagnetic fields and/or a heat bath are described, pair production at finite temperature is discussed, and finally a glance at photon-neutrino interactions is provided. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0010/0010287v1.pdf"}
{"id": "hep-ph0105170", "abstract": "  Color superconductivity of QCD at finite density, temperature and flavor asymmetry is studied within an approximation which the interaction is modeled upon four–fermion interactions. We calculate the thermodynamic potential in the so-called NJL-type model and study the phase structure at finite density, temperature and flavor asymmetry. We find that a mixed phase appears at sufficiently large flavor asymmetry and low temperature. A tricritical point in the T-μ_B-μ_I plane is also found. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0105/0105170v1.pdf"}
{"id": "hep-ph0112268", "abstract": "  We consider double spin asymmetries for longitudinally polarized leptons and transversely polarized protons in diffractive vector meson and Q Q̅ production at high energies within the two-gluon model. The asymmetry predicted for meson production is quite small. The A_lT asymmetry for Q Q̅ production contains two independent terms which are large and can be used to obtain information on the polarized gluon distributions in the proton. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0112/0112268v2.pdf"}
{"id": "hep-ph0203008", "abstract": "  We investigate the symmetry properties for Baym's Φ-derivable schemes. We show that in general the solutions of the dynamical equations of motion, derived from approximations of the Φ-functional, do not fulfill the Ward-Takahashi identities of the symmetry of the underlying classical action, although the conservation laws for the expectation values of the corresponding Noether currents are fulfilled exactly for the approximation. Further we prove that one can define an effective action functional in terms of the self-consistent propagators which is invariant under the operation of the same symmetry group representation as the classical action. The requirements for this theorem to hold true are the same as for perturbative approximations: The symmetry has to be realized linearly on the fields and it must be free of anomalies, i.e., there should exist a symmetry conserving regularization scheme. In addition, if the theory is renormalizable in Dyson's narrow sense, it can be renormalized with counter terms which do not violate the symmetry. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0203/0203008v3.pdf"}
{"id": "hep-ph0208005", "abstract": "  It is an exciting time for flavor physics. In this talk, I discuss recent topics in baryogenesis and leptogenesis in light of new data, and implications in B and neutrino physics. I also discuss current situation of grand unified theories concerning coupling unification, proton decay, and indirect consequences in lepton flavor violation and B physics. I explain attempts to understand the origin of flavor based on flavor symmetry, in particular \"anarchy\" in neutrinos. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0208/0208005v1.pdf"}
{"id": "hep-ph0301251", "abstract": "  Several works analyzing the new physics contributions from the Left-Right Symmetric Model to the CP violation phenomena in the neutral B mesons can be found in the literature. These works exhibit interesting and experimentally sensible deviations from the Standard Model predictions but at the expense of considering a low right scale υ_R around 1 TeV. However, when we stick to the more conservative estimates for υ_R which say that it must be at least 10^7 GeV, no experimentally sensible deviations from the Standard Model appear for indirect CP violation. This estimate for υ_R arises when the generation of neutrino masses is considered. In spite of the fact that this scenario is much less interesting and says nothing new about both the CP violation phenomenon and the structure of the Left-Right Symmetric Model, this possibility must be taken into account for the sake of completeness and when considering the see-saw mechanism that provides masses to the neutrino sector. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0301/0301251v3.pdf"}
{"id": "hep-ph0305091", "abstract": "  A recently developed model for the QCD analytic invariant charge is compared with quenched lattice simulation data on the static quark-antiquark potential. By employing this strong running coupling one is able to obtain the confining quark-antiquark potential in the framework of the one-gluon exchange model. To achieve this objective a technique for evaluating the integrals of a required form is developed. Special attention is paid here to removing the divergences encountered the calculations. All this enables one to examine the asymptotic behavior of the potential at both small and large distances with high accuracy. An explicit expression for the quark-antiquark potential, which interpolates between these asymptotics, and satisfies the concavity condition, is proposed. The derived potential coincides with the perturbative results at small distances, and it is in a good agreement with the lattice data in the nonperturbative physically-relevant region. An estimation of the parameter Λ_QCD is obtained for the case of pure gluodynamics. It is found to be consistent with all the previous estimations of Λ_QCD in the framework of approach in hand. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0305/0305091v2.pdf"}
{"id": "hep-ph0404170", "abstract": "  We construct QCD sum rules for the anti-charmed pentaquark Θ_c (3099), recently reported at HERA. The sum rules are constructed similarly with the Θ^+ (1540) sum rules using the anti-charmed analogue of the Θ^+ interpolating field. The strange quark and quark-gluon mixed condensates, which were important in the Θ^+ sum rules, are replaced by the gluon condensates whose contribution to the OPE is suppressed due to the heavy quark mass. Our result suggests that the parity of Θ_c is positive. We identify the difference from the Θ^+ sum rule, which leads to the positive parity in this heavy-light pentaquark system. The obtained mass is similar to the experimental value. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0404/0404170v3.pdf"}
{"id": "hep-ph0406088", "abstract": "  The naturalness criterion applied to the cosmological constant implies a new-physics threshold at 10^-3 eV. Either the naturalness criterion fails, or this threshold does not influence particle dynamics at higher energies. It has been suggested that the Higgs naturalness problem may follow the same fate. We investigate this possibility and, abandoning the hierarchy problem, we use unification and dark matter as the only guiding principles. The model recently proposed by Arkani-Hamed and Dimopoulos emerges as a very interesting option. We study it in detail, analysing its structure, and the conditions for obtaining unification and dark matter. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0406/0406088v2.pdf"}
{"id": "hep-ph0512365", "abstract": "  We construct a new Monte Carlo generator of events for neutrino interactions. The dynamical models for quasi-elastic reactions, Δ excitation and more inelastic events described by the DIS formalism with the PDFs modified according to recent JLab data are used. We describe in detail single pion production channels, which combine the Δ excitation and DIS contribution. Many comparisons of the outcome of simulations with experimental data are presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0512/0512365v1.pdf"}
{"id": "hep-ph0609198", "abstract": "  The role of the strange quark mass for the phase structure of QCD at non-vanishing densities is studied by employing a recently developed self-consistent truncation scheme for the Dyson-Schwinger equations of the quark propagators in Landau gauge. Hereby the medium modification of the effective quark interaction by the polarization of gluons is implemented. Taking into account this effect results in significantly smaller dynamical quark masses at the Fermi surface. Due to this reduction the color-flavor locked phase is always the preferred color-superconducting phase at zero temperature and for a realistic strange quark mass. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0609/0609198v1.pdf"}
{"id": "hep-ph9311266", "abstract": "  It is shown that the number of independent weak form factors collapses if the heavy diquark exists inside the baryons containing a single heavy quark. The relations between the weak form factors are quite different in the case of light diquark. So a careful analysis on the future data of the weak form factors would clarify that in those baryons the correlation between the heavy quark and a light quark is stronger or weaker than the one between two light quarks. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9311/9311266v2.pdf"}
{"id": "hep-ph9605230", "abstract": "  We study the mass spectrum and the eigenstates of the scalar sectors in 3-3-1 models. We show that, in one of the models, the physical scalar masses lead to theoretical constraints to the vacuum expectation values. The models allow very light Higgs bosons. One of the neutral scalars can be identified with the standard model one. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9605/9605230v1.pdf"}
{"id": "hep-ph9706491", "abstract": "  A perturbative QCD calculation of heavy flavor quark fragmentation into heavy flavor baryons is developed along the lines of corresponding heavy meson models. The non-perturbative formation of the baryon is accomplished by implementing the quark-diquark model of the baryons. Diquark color form factors are used to enable the integration over the virtual heavy quark momentum. The resulting spin independent functions for charmed and bottom quarks to fragment into charmed and bottom baryons with spin 1/2 and 3/2 are compared with recent data. Predictions are made for the spin dependent fragmentation functions as well, particularly for the functions ĝ_1 and ĥ_1 in the case of spin 1/2 baryons. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9706/9706491v1.pdf"}
{"id": "hep-ph9711216", "abstract": "  In the framework of gauge-mediated supersymmetry breaking models pair production of the lightest neutralinos, scalar leptons, or charginos at LEPII gives rise to interesting signals involving multilepton final states and missing energy. In the parameter space where the scalar tau, τ̃_1, is the next-to-lightest supersymmetric particle, we identify three interesting regions, which give rise to distinctly different final states: (i) 2 τ-leptons plus missing energy, (ii) 4 charged leptons plus missing energy where in some regions all four are τ-leptons, or (iii) six charged leptons, of which four are τ-leptons and the other two are electrons or muons, plus missing energy. We study in detail the size of these regions in the parameter space of gauge-mediated models and give cross section contours in these regions for various LEPII energies. We also discuss the possibility of chargino-pair production at LEPII. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9711/9711216v2.pdf"}
{"id": "hep-ph9806265", "abstract": "  A second order, O(α ^2_s), calculation in perturbative quantum chromodynamics is presented of the longitudinal spin dependence of the cross section for the two particle inclusive reaction p + p →γ + c + X for large values of the transverse momentum of the prompt photon and charm quark. Differential distributions are provided for the spin-averaged cross section and for the two-spin longitudinal polarization asymmetry A_LL at the energy of the Brookhaven Relativistic Heavy Ion Collider. An assessment is given of the prospects for determination of the spin dependence of the charm quark density. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9806/9806265v1.pdf"}
{"id": "hep-ph9905275", "abstract": "  We construct a supersymmetric theory of flavor based on the discrete gauge group (D_6)^2, where D_6 describes the symmetry of a regular hexagon under proper rotations in three dimensions. The representation structure of the group allows one to distinguish the third from the lighter two generations of matter fields, so that in the symmetry limit only the top quark Yukawa coupling is allowed and scalar superpartners of the first two generations are degenerate. Light fermion Yukawa couplings arise from a sequential breaking of the flavor symmetry, and supersymmetric flavor-changing processes remain adequately suppressed. We contrast our model with others based on non-Abelian discrete gauge symmetries described in the literature, and discuss the challenges in constructing more minimal flavor models based on this approach. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9905/9905275v1.pdf"}
{"id": "hep-ph9910415", "abstract": "  In this talk I describe work on computing non-leptonic matrix elements consistently with both long and short distance contributions included. On the simpler example of the π^+-π^0 mass difference I explain in detail the matching procedure and the difference between various low-energy models. I then explain the new difficulties in non-leptonic Kaon decays and how the matching here can in principle be done in the same way when scheme dependences are correctly accounted for. In the end I summarize the results J. Prades and I obtain for the Δ I=1/2 rule and B_6. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9910/9910415v1.pdf"}
{"id": "hep-th0106274", "abstract": "  The inflaton potential in four-dimensional theory is rather arbitrary, and fine-tuning is required generically. By contrast, inflation in the brane world scenario has the interesting feature that the inflaton potential is motivated from higher dimensional gravity, or more generally, from bulk modes or string theory. We emphasize this feature with examples. We also consider the impact on the spectrum of density perturbation from a velocity-dependent potential between branes in the brane inflationary scenario. It is likely that such a potential can have an observable effect on the ratio of tensor to scalar perturbations. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0106/0106274v2.pdf"}
{"id": "hep-th0212126", "abstract": "  We compute the Euclidean actions of a d-dimensional charged rotating black brane both in the canonical and the grand-canonical ensemble through the use of the counterterms renormalization method, and show that the logarithmic divergencies associated with the Weyl anomalies and matter field vanish. We obtain a Smarr-type formula for the mass as a function of the entropy, the angular momenta, and the electric charge, and show that these quantities satisfy the first law of thermodynamics. Using the conserved quantities and the Euclidean actions, we calculate the thermodynamics potentials of the system in terms of the temperature, angular velocities, and electric potential both in the canonical and grand-canonical ensembles. We also perform a stability analysis in these two ensembles, and show that the system is thermally stable. This is commensurate with the fact that there is no Hawking-Page phase transition for a black object with zero curvature horizon. Finally, we obtain the logarithmic correction of the entropy due to the thermal fluctuation around the equilibrium. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0212/0212126v2.pdf"}
{"id": "hep-th0601121", "abstract": "  We show the twisted Galilean invariance of the noncommutative parameter, even in presence of space-time noncommutativity. We then obtain the deformed algebra of the Schrödinger field in configuration and momentum space by studying the action of the twisted Galilean group on the non-relativistic limit of the Klein-Gordon field. Using this deformed algebra we compute the two particle correlation function to study the possible extent to which the previously proposed violation of the Pauli principle may impact at low energies. It is concluded that any possible effect is probably well beyond detection at current energies. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0601/0601121v2.pdf"}
{"id": "hep-th0702201", "abstract": "  The phase diagram of the massive chiral Gross-Neveu model (the 1+1-dimensional Nambu-Jona-Lasinio model at large N) is investigated in the vicinity of the tricritical point. Using the derivative expansion, the grand canonical potential is cast into the form of a Ginzburg-Landau effective action. Minimization of this action by variational and numerical methods reveals both 1st and 2nd order phase transitions to a chiral crystal phase, separated by a tricritical line. These findings are contrasted to the massive Gross-Neveu model with discrete chiral symmetry where only 2nd order transitions have been observed. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0702/0702201v2.pdf"}
{"id": "hep-th9407170", "abstract": "  It is showed how the Hamiltonian lattice loop representation can be cast straightforwardly in the Lagrangian formalism. The procedure is general and here we present the simplest case: pure compact QED. This connection has been shaded by the non canonical character of the algebra of the fundamental loop operators. The loops represent tubes of electric flux and can be considered the dual objects to the Nielsen-Olesen strings supported by the Higgs broken phase. The lattice loop classical action corresponding to the Villain form is proportional to the quadratic area of the loop world sheets and thus it is similar to the Nambu string action. This loop action is used in a Monte Carlo simulation and its appealing features are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/9407/9407170v1.pdf"}
{"id": "hep-th9704110", "abstract": "  These lectures are intended as an introduction to some of the basic aspects of string solitons, duality and black holes. We begin with a discussion of the role of classical solutions in duality, then focus on string/string duality and fundamental membranes. Finally, we examine the feature of compositeness of string solitons, and its implications for bound states and black hole thermodynamics. As these lectures are aimed primarily at those less familiar with this field, technical details are minimized. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/9704/9704110v2.pdf"}
{"id": "hep-th9711098", "abstract": "  The BPS spectrum of type I' string theory in a generic background is derived using the duality with the nine-dimensional heterotic string theory with Wilson lines. It is shown that the corresponding mass formula has a natural interpretation in terms of type I', and it is demonstrated that the relevant states in type I' preserve supersymmetry. By considering certain BPS states for different Wilson lines an independent confirmation of the string creation phenomenon in the D0-D8 system is found. We also comment on the non-perturbative realization of gauge enhancement in type I', and on the predictions for the quantum mechanics of type I' D0-branes. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/9711/9711098v1.pdf"}
{"id": "hep-th9901114", "abstract": "  A geometric definition for a magnetic charge of Abelian monopoles in SU(N) lattice gauge theories with Higgs fields is presented. The corresponding local monopole number defined for almost all field configurations does not require gauge fixing and is stable against small perturbations. Its topological content is that of a 3-cochain. A detailed prescription for calculating the local monopole number is worked out. Our method generalizes a magnetic charge definition previously invented by Phillips and Stone for SU(2). ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/9901/9901114v1.pdf"}
{"id": "math-ph0609015", "abstract": "  We consider a physical system which is coupled indirectly to a Markovian resevoir through an oscillator mode. This is the case, for example, in the usual model of an atomic sample in a leaky optical cavity which is ubiquitous in quantum optics. In the strong coupling limit the oscillator can be eliminated entirely from the model, leaving an effective direct coupling between the system and the resevoir. Here we provide a mathematically rigorous treatment of this limit as a weak limit of the time evolution and observables on a suitably chosen exponential domain in Fock space. The resulting effective model may contain emission and absorption as well as scattering interactions. ", "pdf_url": "gs://arxiv-dataset/arxiv/math-ph/pdf/0609/0609015v1.pdf"}
{"id": "math0605064", "abstract": "  We propose a pricing technique based on coherent risk measures, which enables one to get finer price intervals than in the No Good Deals pricing. The main idea consists in splitting a liability into several parts and selling these parts to different agents. The technique is closely connected with the convolution of coherent risk measures and equilibrium considerations.   Furthermore, we propose a way to apply the above technique to the coherent estimation of the Greeks. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0605/0605064v1.pdf"}
{"id": "mtrl-th9605001", "abstract": "  The melting curve for MgO was obtained using molecular dynamics and a non-empirical, many-body potential. We also studied premelting effects by computing the dynamical structure factor in the crystal on approach to melting. The melting curve simulations were performed with periodic boundary conditions with cells up to 512 atoms using the ab-initio Variational Induced Breathing (VIB) model. The melting curve was obtained by computing ", "pdf_url": "gs://arxiv-dataset/arxiv/mtrl-th/pdf/9605/9605001v1.pdf"}
{"id": "nlin0506012", "abstract": "  Nonlocal nonlinear Schroedinger-type equation is derived as a model to describe paraxial light propagation in nonlinear media with different `degrees' of nonlocality. High frequency limit of this equation is studied under specific assumptions of Cole-Cole dispersion law and a slow dependence along propagating direction. Phase equations are integrable and they correspond to dispersionless limit of Veselov-Novikov hierarchy. Analysis of compatibility among intensity law (dependence of intensity on the refractive index) and high frequency limit of Poynting vector conservation law reveals the existence of singular wavefronts. It is shown that beams features depend critically on the orientation properties of quasiconformal mappings of the plane. Another class of wavefronts, whatever is intensity law, is provided by harmonic minimal surfaces. Illustrative example is given by helicoid surface. Compatibility with first and third degree nonlocal perturbations and explicit solutions are also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0506/0506012v2.pdf"}
{"id": "nlin0610014", "abstract": "  We examine the dynamics of semiconductor lasers coupled in a ring configuration. The lasers, which have stable output intensity when isolated, behave chaotically when coupled unidirectionally in a closed chain. In this way, we show that neither feedback nor bidirectional coupling is necessary to induce chaotic dynamics at the laser output. We study the synchronization phenomena arising in this particular coupling architecture, and discuss its possible application to chaos-based communications. Next, we extend the study to bidirectional coupling and propose an appropriate technique to optical chaos encryption/decryption in closed chains of mutually coupled semiconductor lasers. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0610/0610014v1.pdf"}
{"id": "nucl-ex0105014", "abstract": "  Transverse momentum spectra for identified π^0's in the range 1 GeV/c < p_T < 4 GeV/c have been measured by the PHENIX experiment in Au-Au collisions at √(s)=130 GeV. The spectra from peripheral nuclear collisions are consistent with the simple expectation of scaling the spectra from p+p collisions by the average number of nucleon-nucleon binary collisions. The spectra from central collisions and the ratio of central/peripheral spectra are significantly suppressed when compared to point-like scaling. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/0105/0105014v1.pdf"}
{"id": "nucl-ex0301009", "abstract": "  We present new experimental data on directed flow in collisions of Au+Au, Xe+CsI and Ni+Ni at incident energies from 90 to 400A MeV. We study the centrality and system dependence of integral and differential directed flow for particles selected according to charge. All the features of the experimental data are compared with Isospin Quantum Molecular Dynamics (IQMD) model calculations in an attempt to extract information about the nuclear matter equation of state (EoS). We show that the combination of rapidity and transverse momentum analysis of directed flow allow to disentangle various parametrizations in the model. At 400A MeV, a soft EoS with momentum dependent interactions is best suited to explain the experimental data in Au+Au and Xe+CsI, but in case of Ni+Ni the model underpredicts flow for any EoS. At 90A MeV incident beam energy, none of the IQMD parametrizations studied here is able to consistently explain the experimental data. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/0301/0301009v1.pdf"}
{"id": "nucl-ex0404005", "abstract": "  A great deal of recent data on event-by-event fluctuation and correlation measurements has been released by several experiments at the SPS and RHIC. Recent results on charge fluctuations, balance functions in pseudorapidity, and average transverse momentum fluctuations will be reviewed. The results will be compared to various model predictions after examining contributions to each observable from known physics processes. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/0404/0404005v1.pdf"}
{"id": "nucl-ex0508010", "abstract": "  A novel decomposition technique is used to extract the centrality dependence of di-jet properties and yields from azimuthal correlation functions obtained in Au+Au collisions at √(s__ NN)=200 GeV. The width of the near-side jet shows very little dependence on centrality. In contrast, the away-side jet indicates substantial broadening as well as hints for for a local minimum at Δϕ=π for central and mid-central events. The yield of jet-pairs (per trigger particle) slowly increases with centrality for both the near- and away-side jets. These observed features are compatible with several recent theoretical predictions of possible modifications of di-jet fragmentation by a strongly interacting medium. Several new experimental approaches, including the study of flavor permutation and higher order multi-particle correlations, that might help to distinguish between different theoretical scenarios are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/0508/0508010v1.pdf"}
{"id": "nucl-ex0609032", "abstract": "  This report describes the computer program GKINT, which was developed to plan, analyze and interpret the first High Velocity Transient Field (HVTF) g-factor measurements on radioactive beams produced as fast fragments. The computer program and these notes were written in September 2004. Minor corrections and updates have been added to these notes since then. The experiment, NSCL experiment number 02020, 'Excited-state configurations in S-38 and S-40 through transient-field g-factor measurements on fast fragments', was performed in October 2004; results have been published in Physical Review Letters 96, 112503 (2006). ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/0609/0609032v1.pdf"}
{"id": "nucl-ex9905005", "abstract": "  We review the experimental results on strangeness and antibaryon production in heavy-ion collisions at the AGS and SPS. We argue that the observed enhancement in kaon production at the AGS is consistent with hadronic description, while the multistrange baryon and antibaryon results at the SPS may need physics beyond hadronic nature. We call the need for measurements of low energy antilambda-proton annihilation cross-section in the modeling of antilambda to antiproton ratio; large value of this ratio is observed in central heavy-ion collisions at the AGS and SPS. We speculate the importance of an excitation function measurement of the ratio. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/9905/9905005v2.pdf"}
{"id": "nucl-th0002021", "abstract": "  The structure of the N=50 isotones 98Cd, 97Ag, and 96Pd is studied in terms of shell model employing a realistic effective interaction derived from the Bonn-A nucleon-nucleon potential. The single-hole energies are fixed by resorting to an analysis of the low-energy spectra of the isotones with A>= 91. Comparison shows that our results are in very satisfactory agreement with the available experimental data. This supports confidence in the predictions of our calculations ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0002/0002021v3.pdf"}
{"id": "nucl-th0003067", "abstract": "  The baryon distribution is studied by using a parton cascade model which is based on pQCD incorporating hard partonic scattering and dynamical hadronization scheme. In order to study baryon distribution,baryonic cluster formation is newly implemented as well as hadronic higher resonance states from parton/beam cluster decay. The net baryon number and charged hadron distributions are calculated with different K-factors in which parameters are fixed by elementary pp̅ data at E_c.m.=200 GeV. It is found that baryon stopping behavior at SPS and RHIC energies are not consequence of hard parton scattering but soft processes. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0003/0003067v1.pdf"}
{"id": "nucl-th0202065", "abstract": "  Various phenomenological models of particle multiplicity distributions are discussed using a general form of the grand canonical partition function. These phenomenological models include a wide range of varied processes such as coherent emission or Poisson processes, chaotic emission resulting in a negative binomial distribution, combinations of coherent and chaotic processes called signal/noise distributions, and models based on field emission from Lorentzian line shapes leading to Lorentz/Catalan distributions. These specific cases can be written as special cases of a more general distribution. Using this grand canonical approach moments and cumulants, combinants, hierarchical structure, void scaling relations, KNO scaling features, clan variables and branching laws associated with stochastic or ancestral variables are discussed. It is shown that just looking at the mean and fluctuation of data is not enough to distinguish these distributions or the underlying mechanism. A generalization of the Poisson transform of a distribution and the Poissonian decomposition of it into a compound or sequential process is also given. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0202/0202065v1.pdf"}
{"id": "nucl-th0306050", "abstract": "  We calculated the contribution of internal nucleon electric dipole moments to the Schiff moment of ^199Hg. The contribution of the proton electric dipole moment was obtained via core polarization effects that were treated in the framework of random phase approximation with effective residual forces. We derived a new upper bound |d_p|< 5.4× 10^-24 e·cm of the proton electric dipole moment. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0306/0306050v3.pdf"}
{"id": "nucl-th0404006", "abstract": "  Heavy quark energy loss in a hot QCD plasma is computed taking into account the competing effects due to suppression of zeroth order gluon radiation bellow the plasma frequency and the enhancement of gluon radiation due to transition energy loss and medium induced Bremsstrahlung. Heavy quark medium induced radiative energy loss is derived to all orders in opacity, (L/λ_g)^n. Numerical evaluation of the energy loss suggest small suppression of high p_⊥ charm quarks, and therefore provide a possible explanation for the null effects observed by PHENIX in the prompt electron spectrum in Au+Au as √(s)=130 and 200 AGeV. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0404/0404006v2.pdf"}
{"id": "nucl-th0501016", "abstract": "  The low-lying isovector dipole strengths in neutron rich nuclei ^26Ne and ^28Ne are investigated in the quasiparticle relativistic random phase approximation. Nuclear ground state properties are calculated in an extended relativistic mean-field theory plus BCS method where the contribution of the resonant continuum to pairing correlations is properly treated. Numerical calculations are tested in the case of isovector dipole and isoscalar quadrupole modes in the neutron rich nucleus ^22O. It is found that in present calculation low-lying isovector dipole strengths at E_x < 10 MeV in nuclei ^26Ne and ^28Ne exhaust about 4.9", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0501/0501016v1.pdf"}
{"id": "nucl-th0601041", "abstract": "  The isoscalar and isovector collective multipole excitations in stable nuclei are studied in the framework of relativistic random-phase approximation with the vacuum polarization arising from the nucleon-antinucleon field. A fully self-consistent calculation which guarantees the decoupling of the spurious state and the conservation of the multipole-transition current is carried out by using the derivative-expansion method for the description of the vacuum contribution. A remarkable effect of the inclusion of the vacuum polarization is the increase of the effective mass, m^*/m_N ∼ 0.8; for all multipole modes, the energy-weighted sum rule values with the vacuum polarization are smaller than those of the relativistic model without the vacuum polarization, which typically has the effective mass m^*/m_N ∼ 0.6. Also, the present model can give an excellent agreement with experimental data on the excitation energy, in particular, for the isoscalar quadrupole resonances in which it was previously reported that the calculated energies in the relativistic model are about 1-2 MeV above the experimental values. It is shown, further, that the change of the shell structure due to the inclusion of the vacuum polarization plays an important role in the improvement of the discrepancies seen in the dipole compression modes. On the other hand, the isoscalar monopole resonance has a similar peak whether or not the vacuum polarization is taken into account, if the compression modulus is kept the same in the analysis. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0601/0601041v2.pdf"}
{"id": "nucl-th0702065", "abstract": "  We present the evolution of the shell structure of nuclei in Hartree-Fock calculations using Skyrme's density-dependent effective nucleon-nucleon interaction. The role of the tensor part of the Skyrme interaction to the Hartree-Fock spin-orbit splitting in spherical spin unsaturated nuclei is reanalyzed. The contribution of a finite range tensor force to the spin-orbit splitting in closed shell nuclei is calculated. It is found that the exact matrix elements of a Gaussian and of a one-pion exchange tensor potential could be written as a product Skyrme's short range expression times a suppression factor which is almost constant for closed shell nuclei with mass number A≥ 48. The suppression factor is ∼ 0.15 for the one-pion exchange potential. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0702/0702065v2.pdf"}
{"id": "nucl-th9812061", "abstract": "  We study the coherent photoproduction of pseudoscalar mesons—particularly of neutral pions—placing special emphasis on the various sources that put into question earlier nonrelativistic-impulse-approximation calculations. These include: final-state interactions, relativistic effects, off-shell ambiguities, and violations to the impulse approximation. We establish that, while distortions play an essential role in the modification of the coherent cross section, the uncertainty in our results due to the various choices of optical-potential models is relatively small (of at most 30", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/9812/9812061v1.pdf"}
{"id": "nucl-th9908013", "abstract": "  We suggest two methods for the detection of the formation of disoriented chiral condensates in heavy ion collisions. We show that the variance in the number of charged pions (in a suitable range of momentum space) provides a signature for the observation of a disoriented chiral condensate. The signal should be observable even if multiple domains of DχC form provided the average number of pions per domain is significantly larger than unity. The variance of the number charged pions alone provides a signal which can be used even if the number of neutral pions cannot be measured in a given detector. On the other hand, the probability distribution in R, the proportion of neutral pions to all pions emitted in heavy ion collisions in certain kinematic regions, has been suggested as a signal of a disoriented chiral condensate. Here we note that the signature can be greatly enhanced by making suitable cuts in the data. In particular, we consider reducing the data set such that the k pions with lowest p_T are all neutral. We find that, given such cuts, <R> can be substantially different from 1/3. For example, for a single DχC domain without contamination due to incoherently emitted pions, <R> is 3/5 given the pion with lowest p_T is neutral, and 5/7 given the two pions with lowest p_T are both neutral, etc.. The effects of multi-domain DχC formation and noise due to incoherent pion emission can be systematically incorporated. Potential applications to experiments and their limitations are briefly discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/9908/9908013v1.pdf"}
{"id": "nucl-th9908028", "abstract": "  I describe four serious defects of a widely discussed pion exchange model for interquark forces: it doesn't solve the \"spin-orbit problem\" as advertised, it fails to describe the internal structure of baryon resonances, it leads to disastrous conclusions when extended to mesons, and it is not reasonably connected to the physics of heavy-light systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/9908/9908028v2.pdf"}
{"id": "physics0005005", "abstract": "  A conceptual design is presented for a high power cupronickel pion production target. It forms a circular band in a horizontal plane with approximate dimensions of: 2.5 meters radius, 6 cm high and 0.6 cm thick. The target is continuously rotated at 3 m/s to carry heat away from the production region to a water cooling channel. Bunches of 16 GeV protons with total energies of 270 kJ and repetition rates of 15 Hz are incident tangentially to arc of the target along the symmetry axis of a 20 Tesla solenoidal magnetic capture channel. The mechanical layout and cooling setup are described. Results are presented from realistic MARS Monte Carlo computer simulations of the pion yield and energy deposition in the target. ANSYS finite element calculations are beginning to give predictions for the resultant shock heating stresses. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0005/0005005v1.pdf"}
{"id": "physics0101097", "abstract": "  When a laser pulse impinges on a molecule which is invariant under certain symmetry operations selection rules for harmonic generation (HG) arise. In other words: symmetry controls which channels are open for the deposition and emission of laser energy—with the possible application of filtering or amplification. We review the derivation of HG selection rules and study numerically the interaction of laser pulses with an effectively one-dimensional ring-shaped model molecule. The harmonic yields obtained from that model and their dependence on laser frequency and intensity are discussed. In a real experiment obvious candidates for such molecules are benzene, other aromatic compounds, or even nanotubes. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0101/0101097v1.pdf"}
{"id": "physics0112088", "abstract": "  For studying the group theoretical classification of the solutions of the density functional theory in relativistic framework, we propose quantum electrodynamical density-matrix functional theory (QED-DMFT). QED-DMFT gives the energy as a functional of a local one-body 4×4 matrix Q(x)≡ -<ψ(x)ψ̅(x)>, where ψ and ψ̅ are 4-component Dirac field and its Dirac conjugate, respectively. We examine some characters of QED-DMFT. After these preparations, by using Q(x), we classify the solutions of QED-DMFT under O(3) rotation, time reversal and spatial inversion. The behavior of Q(x) under nonrelativistic and ultrarelativistic limits are also presented. Finally, we give plans for several extensions and applications of QED-DMFT. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0112/0112088v1.pdf"}
{"id": "physics0305069", "abstract": "  A Grid testbed has been established using resources at 12 sites across Canada involving researchers from particle physics as well as other fields of science. We describe our use of the testbed with the BaBar Monte Carlo production and the ATLAS data challenge software. In each case the remote sites have no application-specific software stored locally and instead access the software and data via AFS and/or GridFTP from servers located in Victoria. In the case of BaBar, an Objectivity database server was used for data storage. We present the results of a series of initial tests of the Grid testbed using both BaBar and ATLAS applications. The initial results demonstrate the feasibility of using generic Grid resources for HEP applications. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0305/0305069v1.pdf"}
{"id": "physics0406129", "abstract": "  We review a novel method for characterizing both the spectral and spatial properties of resonant cavities within two-dimensional photonic crystals (PCs). An optical fiber taper serves as an external waveguide probe whose micron-scale field is used to source and couple light from the cavity modes, which appear as resonant features in the taper's wavelength-dependent transmission spectrum when it is placed within the cavity's near field. Studying the linewidth and depth of these resonances as a function of the taper's position with respect to the resonator produces quantitative measurements of the quality factor Q and modal volume Veff of the resonant cavity modes. Polarization information about the cavity modes can be obtained by studying their depths of coupling when the cavity is probed along different axes by the taper. This fiber-based technique has been used to measure Q   40,000 and Veff   0.9 cubic wavelengths in a graded square lattice PC microcavity fabricated in silicon. The speed and versatility of this fiber-based probe is highlighted, and a discussion of its applicability to other wavelength-scale resonant elements is given. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0406/0406129v1.pdf"}
{"id": "physics0407044", "abstract": "  The problem of non-perturbative description of stationary flames with arbitrary gas expansion is considered. On the basis of the Thomson circulation theorem an implicit integral of the flow equations is constructed. With the help of this integral, a simple explicit expression for the vortex mode of the burnt gas flow near the flame front is obtained. Furthermore, a dispersion relation for the potential mode at the flame front is written down, thus reducing the initial system of bulk equations and jump conditions for the flow variables to a set of integro-differential equations for the flame front position and the flow velocity at the front. The developed approach is applied to the case of thin flames. Finally, an asymptotic expansion of the derived equations is carried out in the case θ→1 where θis the gas expansion coefficient, and a single equation for the front position is obtained in the second post-Sivashinsky approximation. It is demonstrated, in particular, how the well-known problem of correct normalization of the front velocity is resolved in the new approach. It is verified also that in the first post-Sivashinsky approximation, the new equation reduces to the Sivashinsky-Clavin equation corrected according to Cambray and Joulin. Analytical solutions of the derived equations are found, and compared with the results of numerical simulations. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0407/0407044v2.pdf"}
{"id": "physics0411243", "abstract": "  This paper uses an alternative approach to study the monochromatic plane wave propagation within dielectric and conductor linear media of plane-parallel-faces. This approach introduces the time-averaged Poynting vector modulus as field variable. The conceptual implications of this formalism are that the nonequivalence between the time-averaged Poynting vector and the squared-field amplitude modulus is naturally manifested as a consequence of interface effects. Also, two practical implications are considered: first, the exact transmittance is compared with that given by the Beer's Law, employed commonly in experiments. The departure among them can be significative for certain material parameter values. Second, when the exact reflectance is studied for negative permittivity slabs, it is show that the high reflectance can be diminished if a small amount of absorption is present. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0411/0411243v2.pdf"}
{"id": "physics0503058", "abstract": "  We demonstrate a possibility to stabilize three-dimensional spatiotemporal solitons (\"light bullets\") in self–focusing Kerr media by means of a combination of dispersion management in the longitudinal direction (with the group-velocity dispersion alternating between positive and negative values) and periodic modulation of the refractive index in one transverse direction, out of the two. The analysis is based on the variational approximation (results of direct three-dimensional simulations will be reported in a follow-up work). A predicted stability area is identified in the model's parameter space. It features a minimum of the necessary strength of the transverse modulation of the refractive index, and finite minimum and maximum values of the soliton's energy. The former feature is also explained analytically. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0503/0503058v1.pdf"}
{"id": "physics0507006", "abstract": "  We consider the problem of the statistical uncertainty of the correlation matrix in the optimization of a financial portfolio. We show that the use of clustering algorithms can improve the reliability of the portfolio in terms of the ratio between predicted and realized risk. Bootstrap analysis indicates that this improvement is obtained in a wide range of the parameters N (number of assets) and T (investment horizon). The predicted and realized risk level and the relative portfolio composition of the selected portfolio for a given value of the portfolio return are also investigated for each considered filtering method. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0507/0507006v1.pdf"}
{"id": "physics0509049", "abstract": "  Extremely asymmetrical scattering (EAS) is an unusual type of Bragg scattering in slanted periodic gratings with the scattered wave (the +1 diffracted order) propagating parallel to the grating boundaries. Here, a unique and strong sensitivity of EAS to small stepwise variations of mean structural parameters at the grating boundaries is predicted theoretically (by means of approximate and rigorous analyses) for bulk TE electromagnetic waves and slab optical modes of arbitrary polarization in holographic (for bulk waves) and corrugation (for slab modes) gratings. The predicted effects are explained using one of the main physical reasons for EAS–the diffractional divergence of the scattered wave (similar to divergence of a laser beam). The approximate method of analysis is based on this understanding of the role of the divergence of the scattered wave, while the rigorous analysis uses the enhanced T-matrix algorithm. The effect of small and large stepwise variations of the mean permittivity at the grating boundaries is analysed. Two distinctly different and unusual patterns of EAS are predicted in the cases of wide and narrow (compared to a critical width) gratings. Comparison between the approximate and rigorous theories is carried out. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0509/0509049v1.pdf"}
{"id": "physics0511074", "abstract": "  We make systematic measurements of Raman anti-Stokes/Stokes (aS/S) ratios using two different laser excitations (514 and 633 nm) of rhodamine 6G (RH6G) on dried Ag colloids over a wide range of temperatures (100 to 350 K). We show that a temperature scan allows the separation of the contributions to the aS/S ratios from resonance effects and heating/pumping, thus decoupling the two main aspects of the problem. The temperature rise is found to be larger when employing the 633 nm laser. In addition, we find evidence for mode specific vibrational pumping at higher laser power densities. We analyze our results in the framework of ongoing discussion on laser heating/pumping under SERS conditions. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0511/0511074v1.pdf"}
{"id": "physics0512192", "abstract": "  The full exploitation of the physics potential of an International Linear Collider (ILC) requires the development of a polarized positron beam. New concepts of polarized positron sources are based on the development of circularly polarized photon sources. The polarized photons create electron-positron pairs in a thin target and transfer their polarization state to the outgoing leptons. To achieve a high level of positron polarization the understanding of the production mechanisms in the target is crucial. Therefore a general framework for the simulation of polarized processes with GEANT4 is under development. In this contribution the current status of the project and its application to a study of the positron production process for the ILC is presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0512/0512192v1.pdf"}
{"id": "physics0603227", "abstract": "  Relativistic effects on dispersion in a degenerate electron gas are discussed by comparing known response functions derived relativistically (by Jancovici) and nonrelativistically (by Lindhard). The main distinguishing feature is one-photon pair creation, which leads to logarithmic singularities in the response functions. Dispersion curves for longitudinal waves have a similar tongue-like appearance in the relativistic and nonrelativistic case, with the main relativistic effects being on the Fermi speed and the cutoff frequency. For transverse waves the nonrelativistic treatment has a nonphysical feature near the cutoff frequency for large Fermi momenta, and this is attributed to an incorrect treatment of the electron spin. We find (with two important provisos) that one-photon pair creation is allowed in superdense plasmas, implying relatively strong coupling between transverse waves and pair creation. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0603/0603227v1.pdf"}
{"id": "physics0605211", "abstract": "  Theoretical investigations of dynamical behavior in optical parametric oscillators (OPO) have generally assumed that the cavity detunings of the interacting fields are controllable parameters. However, OPOs are known to experience mode hops, where the system jumps to the mode of lowest cavity detuning. We note that this phenomenon significantly limits the range of accessible detunings and thus may prevent instabilities predicted to occur above a minimum detuning from being evidenced experimentally. As a simple example among a number of instability mechanisms possibly affected by this limitation, we discuss the Hopf bifurcation leading to periodic behavior in the monomode mean-field model of a triply resonant OPO and show that it probably can be observed only in very specific setups. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0605/0605211v1.pdf"}
{"id": "physics0606150", "abstract": "  We show that, under conditions of electromagnetically induced transparency (EIT), a significant portion of the incident probe pulse can be transferred into Rayleigh and Raman scattering channels. The light scattered into the Rayleigh channel emerges from the sample with an EIT time delay. We show that a proper description of the probe light propagation in the sample should include, in the diffusion dynamics, a spin polariton generated by the two-photon EIT process. The results have important implications for studies of weak light localization, and for manipulation of single and few photon states in ultracold atomic gases. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0606/0606150v1.pdf"}
{"id": "physics0702085", "abstract": "  A new multiwire proportional chamber (MWPC) was designed and constructed for precision studies of neutron beta decay angular correlations. Its design has several novel features, including the use of low pressure neopentane as the MWPC gas and an entrance window made of thin Mylar sheet reinforced with Kevlar fibers. In the initial off-line performance tests, the gas gain of neopentane and the position resolution were studied. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0702/0702085v1.pdf"}
{"id": "physics0702152", "abstract": "  Several VLBI EOP series were investigated with goal of determination of parameters of the Free Core Nutation (FCN). Both the amplitude and period of the FCN were studied using spectral and wavelet analysis. Our analysis reveals a variability of both the amplitude (known also from other investigations) and the period (or phase) of the FCN nutation. The FCN amplitude varies in the range about 0.1–0.3 mas, and the FCN period – in the range about 415–490 solar days. The latter may be also explained by changes in the FCN phase. Comparison of time variations of the FCN period and amplitude obtained by different authors and methods shows substantial discrepancies at the edges of the period of observations. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0702/0702152v1.pdf"}
{"id": "physics9911014", "abstract": "  This paper investigates the density expansion of the thermodynamic properties of a two component plasma under the influence of a weak constant uniform magnetic field. We start with the fugacity expansion for the Helmholtz free energy. The leading terms with respect to the density are calculated by a perturbation expansion with respect to the magnetic field. We find a new magnetic virial function for a low density plasma which is exact in quadratic order with respect to the magnetic field. Using these results we compute the magnetization and the magnetic susceptibility. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/9911/9911014v1.pdf"}
{"id": "q-bio0403028", "abstract": "  The possibility that the sliding motion of proteins on DNA is influenced by the base sequence through a base pair reading interaction, is considered. Referring to the case of the T7 RNA-polymerase, we show that the protein should follow a noise-influenced sequence-dependent motion which deviate from the standard random walk usually assumed. The general validity and the implications of the results are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/q-bio/pdf/0403/0403028v1.pdf"}
{"id": "quant-ph0003051", "abstract": "  We review results of a recently developed model of a microscopic quantum system interacting with the macroscopic world components which are modeled by collections of bosonic modes. The interaction is via a general operator Λ of the system, coupled to the creation and annihilation operators of the environment modes. We assume that in the process of a nearly instantaneous quantum measurement, the function of the environment involves two distinct parts: the pointer and the bath. Interaction of the system with the bath leads to decoherence such that the system and the pointer both evolve into a statistical mixture state described by the density matrix such that the system is in one of the eigenstates of Λ with the correct quantum mechanical probability, whereas the expectation values of pointer operators retain amplified information on that eigenstate. We argue that this process represents the initial step of a quantum measurement. Calculation of the elements of the reduced density matrix of the system and pointer is carried out exactly, and time dependence of decoherence is identified. We discuss general implications of our model of energy-conserving coupling to a heat bath for processes of adiabatic quantum decoherence. We also evaluate changes in the expectation values of certain pointer operators and suggest that these can be interpreted as macroscopic indicators of the measurement outcome. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0003/0003051v1.pdf"}
{"id": "quant-ph0012073", "abstract": "  We propose an optical double-cavity resonator whose response to a signal is similar to that of an Electromagnetically Induced Transparency (EIT) medium. A combination of such a device with a four-level EIT medium can serve for achieving large cross-Kerr modulation of a probe field by a signal field. This would offer the possibility of building a quantum logic gate based on photonic qubits. We discuss the technical requirements that are necessary for realizing a probe-photon phase shift of Pi caused by a single-photon signal. The main difficulty is the requirement of an ultra-low reflectivity beamsplitter and to operate a sufficiently dense cool EIT medium in a cavity. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0012/0012073v2.pdf"}
{"id": "quant-ph0012096", "abstract": "  We present the conditional time evolution of the electromagnetic field produced by a cavity QED system in the strongly coupled regime. We obtain the conditional evolution through a wave-particle correlation function that measures the time evolution of the field after the detection of a photon. A connection exists between this correlation function and the spectrum of squeezing which permits the study of squeezed states in the time domain. We calculate the spectrum of squeezing from the master equation for the reduced density matrix using both the quantum regression theorem and quantum trajectories. Our calculations not only show that spontaneous emission degrades the squeezing signal, but they also point to the dynamical processes that cause this degradation. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0012/0012096v1.pdf"}
{"id": "quant-ph0305149", "abstract": "  The problems connected with a causality of space-time universe and with the paradox of Einstein, Podolsky, and Rosen are considered. A main philosophical problem and its possible solutions are briefly discussed. A concept of unified local field theory is considered. It is shown that in the framework of such theory there are nonlocal correlations between space separate events. These correlations are predicted by quantum mechanics and they are confirmed by Aspect type experiments for testing of Bell inequality. The presence of these nonlocal correlations in the framework of a local field theory is connected with the fact that its solution is nonlocal in character. Prospects for possible applications of an unified local field theory are considered. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0305/0305149v1.pdf"}
{"id": "quant-ph0310049", "abstract": "  The errors caused by the transitions with large frequency offsets (nonresonant transitions) are calculated analytically for a scalable solid-state quantum computer based on a one-dimensional spin chain with Ising interactions between neighboring spins. Selective excitations of the spins are enabled by a uniform gradient of the external magnetic field. We calculate the probabilities of all unwanted nonresonant transitions associated with the flip of each spin with nonresonant frequency and with flips of two spins: one with resonant and one with nonresonant frequencies. It is shown that these errors oscillate with changing the gradient of the external magnetic field. Choosing the optimal values of this gradient allows us to decrease these errors by 50", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0310/0310049v1.pdf"}
{"id": "quant-ph0311066", "abstract": "  Quantum Key Distribution with the BB84 protocol has been shown to be unconditionally secure even using weak coherent pulses instead of single-photon signals. The distances that can be covered by these methods are limited due to the loss in the quantum channel (e.g. loss in the optical fiber) and in the single-photon counters of the receivers. One can argue that the loss in the detectors cannot be changed by an eavesdropper in order to increase the covered distance. Here we show that the security analysis of this scenario is not as easy as is commonly assumed, since already two-photon processes allow eavesdropping strategies that outperform the known photon-number splitting attack. For this reason there is, so far, no satisfactory security analysis available in the framework of individual attacks. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0311/0311066v2.pdf"}
{"id": "quant-ph0411100", "abstract": "  We formulate two types of electric RLC resonance network equivalent to quantum billiards. In the network of inductors grounded by capacitors squared resonant frequencies are eigenvalues of the quantum billiard. In the network of capacitors grounded by inductors squared resonant frequencies are given by inverse eigen values of the billiard. In both cases local voltages play role of the wave function of the quantum billiard. However as different from quantum billiards there is a heat power because of resistance of the inductors. In the equivalent chaotic billiards we derive the distribution of the heat power which well describes numerical statistics. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0411/0411100v1.pdf"}
{"id": "quant-ph0504165", "abstract": "  Electron spins in semiconductor quantum dots are promising candidates for the experimental realization of solid-state qubits. We analyze the dynamics of a system of three qubits arranged in a linear geometry and a system of four qubits arranged in a square geometry. Calculations are performed for several quantum dot confining potentials. In the three-qubit case, three-body effects are identified that have an important quantitative influence upon quantum computation. In the four-qubit case, the full Hamiltonian is found to include both three-body and four-body interactions that significantly influence the dynamics in physically relevant parameter regimes. We consider the implications of these results for the encoded universality paradigm applied to the four-electron qubit code; in particular, we consider what is required to circumvent the four-body effects in an encoded system (four spins per encoded qubit) by the appropriate tuning of experimental parameters. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0504/0504165v2.pdf"}
{"id": "quant-ph0603045", "abstract": "  In relativity, two simultaneous events at two different places are not simultaneous for observers in different Lorentz frames. In the Einstein-Podolsky-Rosen experiment, two simultaneous measurements are taken at two different places. Would they still be simultaneous to observers in moving frames? It is a difficult question, but it is still possible to study this problem in the microscopic world. In the hydrogen atom, the uncertainty can be considered to be entirely associated with the ground-state. However, is there an uncertainty associated with the time-separation variable between the proton and electron? This time-separation variable is a forgotten, if not hidden, variable in the present form of quantum mechanics. The first step toward the simultaneity problem is to study the role of this time-separation variable in the Lorentz-covariant world. It is shown possible to study this problem using harmonic oscillators applicable to hadrons which are bound states of quarks. It is also possible to derive consequences that can be tested experimentally. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0603/0603045v2.pdf"}
{"id": "quant-ph0606235", "abstract": "  We compute Casimir forces in open geometries with edges, involving parallel as well as perpendicular semi-infinite plates. We focus on Casimir configurations which are governed by a unique dimensional scaling law with a universal coefficient. With the aid of worldline numerics, we determine this coefficient for various geometries for the case of scalar-field fluctuations with Dirichlet boundary conditions. Our results facilitate an estimate of the systematic error induced by the edges of finite plates, for instance, in a standard parallel-plate experiment. The Casimir edge effects for this case can be reformulated as an increase of the effective area of the configuration. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0606/0606235v1.pdf"}
{"id": "quant-ph0612223", "abstract": "  We quantify the total, quantum, and classical correlations with entropic measures, and quantitatively compare these correlations in a quantum system, as exemplified by a Heisenberg dimer which is subjected to the change of environmental parameters: temperature and nonuniform external field. Our results show that the quantum correlation may exceed the classical correlation at some nonzero temperatures, though the former is rather fragile than the later under thermal fluctuation. The effect of the external field to the classical correlation is quite different from the quantum correlation. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0612/0612223v1.pdf"}
{"id": "quant-ph9710021", "abstract": "  Quantum open systems are described in the Markovian limit by master equations in Lindblad form. I argue that common “quantum trajectory” techniques corresponding to continuous measurement schemes, which solve the master equation by unraveling its evolution into stochastic trajectories in Hilbert space, correspond closely to particular sets of decoherent (or consistent) histories. This is illustrated by a simple model of photon counting. An equivalence is shown for these models between standard quantum jumps and the orthogonal jumps of Diósi, which have already been shown to correspond to decoherent histories. This correspondence is compared to simple treatments of trajectories based on repeated or continuous measurements. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/9710/9710021v2.pdf"}
{"id": "quant-ph9809013", "abstract": "  We numerically study 2-photon processes using a set of harmonics from a Ti:Sapphire laser and in particular interference effects in the Above Threshold Ionization spectra. We compare the situation where the harmonic phases are assumed locked to the case where they have a random distribution. Suggestions for possible experiments, using realistic parameters are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/9809/9809013v3.pdf"}
{"id": "quant-ph9912096", "abstract": "  The dynamics of a soliton propagating in a single-mode optical fiber with gain, loss, and Raman coupling to thermal phonons is analyzed. Using both soliton perturbation theory and exact numerical techniques, we predict that intrinsic thermal quantum noise from the phonon reservoirs is a larger source of jitter and other perturbations than the gain-related Gordon-Haus noise, for short pulses, assuming typical fiber parameters. The size of the Raman timing jitter is evaluated for both bright and dark (topological) solitons, and is larger for bright solitons. Because Raman thermal quantum noise is a nonlinear, multiplicative noise source, these effects are stronger for the more intense pulses needed to propagate as solitons in the short-pulse regime. Thus Raman noise may place additional limitations on fiber-optical communications and networking using ultrafast (subpicosecond) pulses. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/9912/9912096v2.pdf"}
{"id": "solv-int9806007", "abstract": "  Linear theory for phonon scattering by discrete breathers in the discrete nonlinear Schroedinger equation using the transfer matrix approach is presented. Transmission and reflection coefficients are obtained as a function of the wave vector of the input phonon. The occurrence of a nonzero transmission, which in fact becomes perfect for a symmetric breather, is shown to be connected with localized eigenmodes thresholds. In the weak-coupling limit, perfect reflection are shown to exist, which requires two scattering channels. A necessary condition for a system to have a perfect reflection is also considered in a general context. ", "pdf_url": "gs://arxiv-dataset/arxiv/solv-int/pdf/9806/9806007v1.pdf"}
{"id": "0704.0178", "abstract": "  We calculate the equation of state of dense hydrogen within the chemical picture. Fluid variational theory is generalized for a multi-component system of molecules, atoms, electrons, and protons. Chemical equilibrium is supposed for the reactions dissociation and ionization. We identify the region of thermodynamic instability which is related to the plasma phase transition. The reflectivity is calculated along the Hugoniot curve and compared with experimental results. The equation-of-state data is used to calculate the pressure and temperature profiles for the interior of Jupiter. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.0178v1.pdf"}
{"id": "0704.1504", "abstract": "  Star patterns, reminiscent of a wide range of diffusively controlled growth forms from snowflakes to Saffman-Taylor fingers, are ubiquitous features of ice covered lakes. Despite the commonality and beauty of these “lake stars” the underlying physical processes that produce them have not been explained in a coherent theoretical framework. Here we describe a simple mathematical model that captures the principal features of lake-star formation; radial fingers of (relatively warm) water-rich regions grow from a central source and evolve through a competition between thermal and porous media flow effects in a saturated snow layer covering the lake. The number of star arms emerges from a stability analysis of this competition and the qualitative features of this meter-scale natural phenomena are captured in laboratory experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.1504v1.pdf"}
{"id": "0704.1583", "abstract": "  Codes to compute mean opacities and radiative accelerations for arbitrary chemical mixtures using the Opacity Project recently revised data have been restructured in a client–server architecture and transcribed as a subroutine library. This implementation increases efficiency in stellar modelling where element stratification due to diffusion processes is depth dependent, and thus requires repeated fast opacity reestimates. Three user modes are provided to fit different computing environments, namely a web browser, a local workstation and a distributed grid. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.1583v1.pdf"}
{"id": "0704.1597", "abstract": "  Using a model of spinless fermions in a lattice with nearest neighbor and next-nearest neighbor interaction we show that the entropy of the reduced two site density matrix (the bond entropy) can be used as an extremely accurate and easy to calculate numerical indicator for the critical parameters of the quantum phase transition when the basic ordering pattern has a two-site periodicity. The actual behavior of the bond entropy depends on the particular characteristics of the transition under study. For the Kosterlitz-Thouless type phase transition from a Luttinger liquid phase to a charge density wave state the bond entropy has a local maximum while in the transition from the Luttinger liquid to the phase separated state the derivative of the bond entropy has a divergence due to the cancelation of the third eigenvalue of the two-site reduced density matrix. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.1597v1.pdf"}
{"id": "0704.3239", "abstract": "  A general ab-initio and non-perturbative method to solve the time-dependent Schrödinger equation (TDSE) for the interaction of a strong attosecond laser pulse with a general atom, i.e., beyond the models of quasi-one-electron or quasi-two-electron targets, is described. The field-free Hamiltonian and the dipole matrices are generated using a flexible B-spline R-matrix method. This numerical implementation enables us to construct term-dependent, non-orthogonal sets of one-electron orbitals for the bound and continuum electrons. The solution of the TDSE is propagated in time using the Arnoldi-Lanczos method, which does not require the diagonalization of any large matrices. The method is illustrated by an application to the multi-photon excitation and ionization of Ne atoms. Good agreement with R-matrix Floquet calculations for the generalized cross sections for two-photon ionization is achieved. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.3239v2.pdf"}
{"id": "0705.0363", "abstract": "  The frictional heating by ion-neutral drift is calculated and its effect on isobaric thermal instability is carried out. Ambipolar drift heating of one-dimensional self-gravitating magnetized molecular slab is used under the assumptions of quasi-magnetohydrostatic and local ionization equilibrium. We see that ambipolar drift heating is inversely proportional to density and its value in some regions of the slab can be significantly larger than the average heating rates of cosmic rays and turbulent motions. The results show that the isobaric thermal instability can occur in some regions of the slab; therefore it may produce the slab fragmentation and formation of the AU-scale condensations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.0363v1.pdf"}
{"id": "0705.1053", "abstract": "  We consider a probabilistic cellular automaton to analyze the stochastic dynamics of a predator-prey system. The local rules are Markovian and are based in the Lotka-Volterra model. The individuals of each species reside on the sites of a lattice and interact with an unsymmetrical neighborhood. We look for the effect of the space anisotropy in the characterization of the oscillations of the species population densities. Our study of the probabilistic cellular automaton is based on simple and pair mean-field approximations and explicitly takes into account spatial anisotropy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.1053v1.pdf"}
{"id": "0705.1788", "abstract": "  A game-theoretic framework is used to study the effect of constellation size on the energy efficiency of wireless networks for M-QAM modulation. A non-cooperative game is proposed in which each user seeks to choose its transmit power (and possibly transmit symbol rate) as well as the constellation size in order to maximize its own utility while satisfying its delay quality-of-service (QoS) constraint. The utility function used here measures the number of reliable bits transmitted per joule of energy consumed, and is particularly suitable for energy-constrained networks. The best-response strategies and Nash equilibrium solution for the proposed game are derived. It is shown that in order to maximize its utility (in bits per joule), a user must choose the lowest constellation size that can accommodate the user's delay constraint. This strategy is different from one that would maximize spectral efficiency. Using this framework, the tradeoffs among energy efficiency, delay, throughput and constellation size are also studied and quantified. In addition, the effect of trellis-coded modulation on energy efficiency is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.1788v1.pdf"}
{"id": "0705.1976", "abstract": "  Experimental studies have shown the ubiquity of altruistic behavior in human societies. The social structure is a fundamental ingredient to understand the degree of altruism displayed by the members of a society, in contrast to individual-based features, like for example age or gender, which have been shown not to be relevant to determine the level of altruistic behavior. We explore an evolutionary model aiming to delve how altruistic behavior is affected by social structure. We investigate the dynamics of interacting individuals playing the Ultimatum Game with their neighbors given by a social network of interaction. We show that a population self-organizes in a critical state where the degree of altruism depends on the topology characterizing the social structure. In general, individuals offering large shares but in turn accepting large shares, are removed from the population. In heterogeneous social networks, individuals offering intermediate shares are strongly selected in contrast to random homogeneous networks where a broad range of offers, below a critical one, is similarly present in the population. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.1976v2.pdf"}
{"id": "0705.2385", "abstract": "  We present a complete analytical solution of a system of Potts spins on a random k-regular graph in both the canonical and microcanonical ensembles, using the Large Deviation Cavity Method (LDCM). The solution is shown to be composed of three different branches, resulting in an non-concave entropy function.The analytical solution is confirmed with numerical Metropolis and Creutz simulations and our results clearly demonstrate the presence of a region with negative specific heat and, consequently, ensemble inequivalence between the canonical and microcanonical ensembles. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.2385v1.pdf"}
{"id": "0706.0832", "abstract": "  KS 1741-293, discovered in 1989 by the X-ray camera TTM in the Kvant module of the Mir space station and identified as an X-ray burster, has not been detected in the hard X band until the advent of the INTEGRAL observatory. Moreover this source has been recently object of scientific discussion, being also associated to a nearby extended radio source that in principle could be the supernova remnant produced by the accretion induced collapse in the binary system. Our long term monitoring with INTEGRAL, covering the period from February 2003 to May 2005, confirms that KS 1741-293 is transient in soft and hard X band. When the source is active, from a simultaneous JEM-X and IBIS data analysis, we provide a wide band spectrum from 5 to 100 keV, that can be fit by a two component model, a multiple blackbody for the soft emission and a Comptonized or a cut-off power law model for the hard component. Finally, by the detection of two X-ray bursters with JEM-X, we confirm the bursting nature of KS 1741-293, including this source in the class of the hard tailed X-ray bursters. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0706/0706.0832v2.pdf"}
{"id": "0706.2248", "abstract": "  We study the influence of dissipation on the switching current statistics of moderately damped Josephson junctions. Different types of both low- and high- T_c junctions with controlled damping are studied. The damping parameter of the junctions is tuned in a wide range by changing temperature, magnetic field, gate voltage, introducing a ferromagnetic layer or in-situ capacitive shunting. A paradoxical collapse of switching current fluctuations occurs with increasing T in all studied junctions. The phenomenon critically depends on dissipation in the junction and is explained by interplay of two counteracting consequences of thermal fluctuations, which on the one hand assist in premature switching into the resistive state and on the other hand help in retrapping back to the superconducting state. This is one of the rare examples of anticorrelation between temperature and fluctuation amplitude of a physically measurable quantity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0706/0706.2248v1.pdf"}
{"id": "0706.3587", "abstract": "  A huge amount of good quality astrophysical data converges towards the picture of a spatially flat universe undergoing the today observed phase of accelerated expansion. This new observational trend is commonly addressed as Precision Cosmology. Despite of the quality of astrophysical surveys, the nature of dark energy dominating the matter-energy content of the universe is still unknown and a lot of different scenarios are viable candidates to explain cosmic acceleration. Methods to test these cosmological models are based on distance measurements and lookback time toward astronomical objects used as standard candles. I discuss the characterizing parameters and constraints of three different classes of dark energy models pointing out the related degeneracy problem which is the signal that more data at low (z= 0- 1), medium (1<z<10) and high (10 <z< 1000) redshift are needed to definitively select realistic models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0706/0706.3587v1.pdf"}
{"id": "0706.4369", "abstract": "  Because of their unique quality, Hubble Space Telescope (HST) data have played an important complementary role in studies of infrared (IR) galaxies conducted with major facilities, as VLT or Spitzer, and will be as well very valuable for future telescopes as Herschel and ALMA. I review here some of the most recent works led by European astronomers on IR galaxies, and discuss the role that HST has had in the study of different IR galaxy populations. I particularly focus the analysis on the GOODS fields, where the multiwavelength data and unique HST coverage have enabled to jointly put constraints on the evolution of star formation activity and stellar-mass growth with cosmic time. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0706/0706.4369v1.pdf"}
{"id": "0707.0059", "abstract": "  Squeezing of a thermal bath introduces new features absent in an open quantum system interacting with an uncorrelated (zero squeezing) thermal bath. The resulting dynamics, governed by a Lindblad-type evolution, extends the concept of a generalized amplitude damping channel, which corresponds to a dissipative interaction with a purely thermal bath. Here we present the Kraus representation of this map, which we call the squeezed generalized amplitude damping channel. As an application of this channel to quantum information, we study the classical capacity of this channel. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0707/0707.0059v2.pdf"}
{"id": "0707.0613", "abstract": "  We investigate the low temperature behaviour of the integrable 1D two-component spinor Bose gas using the thermodynamic Bethe ansatz. We find that for strong coupling the characteristics of the thermodynamics at low temperatures are quantitatively affected by the spin ferromagnetic states, which are described by an effective ferromagnetic Heisenberg chain. The free energy, specific heat, susceptibility and local pair correlation function are calculated for various physical regimes in terms of temperature and interaction strength. These thermodynamic properties reveal spin effects which are significantly different than those of the spinless Bose gas. The zero-field susceptibility for finite strong repulsion exceeds that of a free spin paramagnet. The critical exponents of the specific heat c_v ∼ T^1/2 and the susceptibility χ∼ T^-2 are indicative of the ferromagnetic signature of the two-component spinor Bose gas. Our analytic results are consistent with general arguments by Eisenberg and Lieb for polarized spinor bosons. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0707/0707.0613v2.pdf"}
{"id": "0707.2305", "abstract": "  In this paper we describe ideas about the string landscape, and how to relate it to the physics of the Standard Model of particle physics. First, we give a short status report about heterotic string compactifications. Then we focus on the statistics of D-brane models, on the problem of moduli stabilization, and finally on some attempts to derive a probability wave function in moduli space, which goes beyond the purely statistical count of string vacua. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0707/0707.2305v2.pdf"}
{"id": "0707.4022", "abstract": "  We formulate a general cluster Dual Fermion Approach to nonlocal correlations in crystals. The scheme allows the treatment of long-range correlations beyond cluster DMFT and nonlocal effects in realistic calculations of multiorbital systems. We show that the the simplest approximation exactly corresponds to free cluster DMFT. We further consider the relation between the two-particle Green functions in real and dual variables. We apply this approach by calculating the Green function of the Hubbard model in one dimension starting from the two-site cluster DMFT solution. The result agrees well with the Green function obtained from a DMRG calculation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0707/0707.4022v1.pdf"}
{"id": "0708.2437", "abstract": "  We consider the application of fluctuation relations to the dynamics of coarse-grained systems, as might arise in a hypothetical experiment in which a system is monitored with a low-resolution measuring apparatus. We analyze a stochastic, Markovian jump process with a specific structure that lends itself naturally to coarse-graining. A perturbative analysis yields a reduced stochastic jump process that approximates the coarse-grained dynamics of the original system. This leads to a non-trivial fluctuation relation that is approximately satisfied by the coarse-grained dynamics. We illustrate our results by computing the large deviations of a particular stochastic jump process. Our results highlight the possibility that observed deviations from fluctuation relations might be due to the presence of unobserved degrees of freedom. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0708/0708.2437v2.pdf"}
{"id": "0708.3714", "abstract": "  By considering particles as smeared objects, we investigate the effects of space noncommutativity on the orbits of particles in Schwarzschild spacetime. The effects of space noncommutativity on the value of the precession of the perihelion of particle orbit and deflection of light ray in Schwarzschild geometry are calculated and the stability of circular orbits is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0708/0708.3714v1.pdf"}
{"id": "0708.4020", "abstract": "  In order to understand the composition of planetary nebulae we first need to study the nucleosynthesis occurring in the progenitor star during the thermally-pulsing Asymptotic Giant Branch (AGB) phase. I present an overview of single AGB evolution, with an emphasis on the mixing processes that alter the envelope composition, followed by a discussion of the stellar yields available from single AGB stellar models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0708/0708.4020v1.pdf"}
{"id": "0709.1326", "abstract": "  We have studied the spin-orbit interaction in a high mobility two-dimensional electron gas in a GaInAs/InP heterostructure as a function of an applied gate voltage as well as a function of temperature. Highly sensitive magnetotransport measurements of weak antilocalization as well as measurements of Shubnikov–de Haas oscillations were performed in a wide range of electron sheet concentrations. In our samples the electron transport takes place in the strong spin precession regime in the whole range of applied gate voltages, which is characterized by the spin precession length being shorter than the elastic mean free path. The magnitude of the Rashba spin-orbit coupling parameter was determined by fitting the experimental curves by a simulated quantum conductance correction according to a model proposed recently by Golub [Phys. Rev. B 71, 235310 (2005)]. A comparison of the Rashba coupling parameter extracted using this model with the values estimated from the analysis of the beating pattern in the Shubnikov–de Haas oscillations showed a good agreement. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0709/0709.1326v1.pdf"}
{"id": "0709.1600", "abstract": "  The angular momentum is conserved in fluids with a few exceptions such as ferrofluids. However it can be violated locally in fluid simulations to reduce computational costs. The effects of this violation are investigated using a particle-based simulation method, multi-particle collision dynamics, which can switch on or off angular-momentum conservation. To this end, we study circular Couette flows between concentric and eccentric cylinders, where non-physical torques due to the lack of the angular-momentum conservation are found whereas the velocity field is not affected. In addition, in simulations of fluids with different viscosities in contact and star polymers in solvent, incorrect angular velocities occur. These results quantitatively agree with the theoretical predictions based on the macroscopic stress tensor. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0709/0709.1600v1.pdf"}
{"id": "0709.2406", "abstract": "  We demonstrate an all-optical switch that operates at ultra-low-light levels and exhibits several features necessary for use in optical switching networks. An input switching beam, wavelength λ, with an energy density of 10^-2 photons per optical cross section [σ=λ^2/(2π)] changes the orientation of a two-spot pattern generated via parametric instability in warm rubidium vapor. The instability is induced with less than 1 mW of total pump power and generates several μWs of output light. The switch is cascadable: the device output is capable of driving multiple inputs, and exhibits transistor-like signal-level restoration with both saturated and intermediate response regimes. Additionally, the system requires an input power proportional to the inverse of the response time, which suggests thermal dissipation does not necessarily limit the practicality of optical logic devices. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0709/0709.2406v1.pdf"}
{"id": "0709.2685", "abstract": "  Quantal systems are predicted to show a change-over from exponential decay to power law decay at very long times. Although most theoretical studies predict integer power-law exponents, recent measurements by Rothe et al. of decay luminescence of organic molecules in solution Phys. Rev. Lett. 96 (2006) 163601 found non-integer exponents in most cases. We propose a physical mechanism, within the realm of scattering from potentials with long tails, which produces a continuous range of power law exponents. In the tractable case of the repulsive inverse square potential, we demonstrate a simple relation between the strength of the long range tail and the power law exponent. This system is amenable to experimental scrutiny. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0709/0709.2685v1.pdf"}
{"id": "0709.3256", "abstract": "  We analyze a possibility of quantum criticality (gaplessness) in dimerized antiferromagnetic two- and three-leg spin-1/2 ladders. Contrary to earlier studies of these models, we examine different dimerization patterns in the ladder. We find that ladders with the columnar dimerization order have lower zero-temperature energies and they are always gapped. For the staggered dimerization order, we find the quantum critical lines, in agreement with earlier analyses. The bond mean-field theory we apply, demonstrates its quantitative accuracy and agrees with available numerical results. We conclude that unless some mechanism for locking dimerization into the energetically less favorable staggered configuration is provided, the dimerized ladders do not order into the phase where the quantum criticality occurs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0709/0709.3256v1.pdf"}
{"id": "0709.4642", "abstract": "  Based on quantitative complementarity relations (QCRs), we analyze the multipartite correlations in four-qubit cluster-class states. It is proven analytically that the average multipartite correlation E_ms is entanglement monotone. Moreover, it is also shown that the mixed three-tangle is a correlation measure compatible with the QCRs in this kind of quantum states. More arrestingly, with the aid of the QCRs, a set of hierarchy entanglement measures is obtained rigorously in the present system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0709/0709.4642v3.pdf"}
{"id": "0710.0245", "abstract": "  We present results for the effect of a second massive quark in the relation between the pole and the minimal subtracted quark mass at the three loop level. We also consider the analogous effect for the wave function renormalisation constant. Some technical details of the calculation are given. Our result is phenomenologically relevant for the bottom quark including virtual charm effects. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.0245v1.pdf"}
{"id": "0710.0584", "abstract": "  Ultrahigh energy cosmic rays provide a unique ground for probing new physics. In this talk we review the possibility of testing TeV gravity in interactions of cosmogenic neutrinos and the potential to discover long-lived exotic particles in nucleon-produced air showers, such as gluinos of split-SUSY models or staus of supersymmetric models with a gravitino LSP. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.0584v1.pdf"}
{"id": "0710.1233", "abstract": "  We demonstrate that the evolution of wall-like inhomogeneities in run-away potentials, characteristic of dynamical supersymmetry breaking and moduli stabilisation, is very similar to the evolution of domain wall networks associated with double well potentials. Instabilities that would lead to a rapid decay of domain walls can be significantly ameliorated by compensation effects between a non-degeneracy of the vacua and a biased initial distribution, which can be naturally expected in a wide class or particle physics models that lead to out-of-equilibrium phase transitions. Within this framework, it is possible to obtain domain walls that live long enough to be relevant for the cosmic power spectrum and galaxy clustering, while being compatible with the observed cosmic microwave background anisotropies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.1233v1.pdf"}
{"id": "0710.1757", "abstract": "  Motivated by the recent realization of graphene sensors to detect individual gas molecules, we investigate the adsorption of H2O, NH3, CO, NO2, and NO on a graphene substrate using first-principles calculations. The optimal adsorption position and orientation of these molecules on the graphene surface is determined and the adsorption energies are calculated. Molecular doping, i.e. charge transfer between the molecules and the graphene surface, is discussed in light of the density of states and the molecular orbitals of the adsorbates. The efficiency of doping of the different molecules is determined and the influence of their magnetic moment is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.1757v1.pdf"}
{"id": "0710.2656", "abstract": "  The Pioneer 10/11 spacecraft yielded the most precise navigation in deep space to date. However, their radio-metric tracking data received from the distances between 20–70 astronomical units from the Sun consistently indicated the presence of a small, anomalous, Doppler frequency drift. The drift is a blue frequency shift that can be interpreted as a sunward acceleration of a_P = (8.74 +/- 1.33) x 10^(-10) m/s^2 for each particular spacecraft. This signal has become known as the Pioneer anomaly; the nature of this anomaly remains unexplained.   New Pioneer 10 and 11 radio-metric Doppler data recently became available. The much extended set of Pioneer Doppler data is the primary source for new upcoming investigation of the anomaly. We also have almost entire records of flight telemetry files received from the the Pioneers. Together with original project documentation and newly developed software tools, this additional information is now used to reconstruct the engineering history of both spacecraft. To that extent, a thermal model of the Pioneer vehicles is being developed to study possible contribution of thermal recoil force acting on the two spacecraft. In addition, to improve the accuracy of orbital reconstruction, we developed a new approach that uses actual flight telemetry data during trajectory analysis of radio-metric Doppler files. The ultimate goal of these efforts is to investigate possible contributions of the thermal recoil force to the detected anomalous acceleration. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.2656v1.pdf"}
{"id": "0710.3148", "abstract": "  In this paper, warm inflationary models on a brane scenario are studied. Here we consider slow-roll inflation and high-dissipation regime in a high-energy scenario. General conditions required for these models to be realizable are derived. We describe scalar and tensor perturbations for these scenarios. Specifically we study power-law potentials considering a dissipation parameter to be a constant on the one hand and ϕ dependent on the other hand. We use recent astronomical observations to restrict the parameters appearing in our model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.3148v1.pdf"}
{"id": "0710.3217", "abstract": "  For the sequence defined by a(n) = a(n-1) + gcd(n, a(n-1)) with a(1) = 7 we prove that a(n) - a(n-1) takes on only 1s and primes, making this recurrence a rare \"naturally occurring\" generator of primes. Toward a generalization of this result to an arbitrary initial condition, we also study the limiting behavior of a(n)/n and a transience property of the evolution. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.3217v3.pdf"}
{"id": "0710.3904", "abstract": "  Two delocalized states of metallic zigzag carbon nanotubes near the Dirac point can be localized by the Aharanov-Bohm magnetic field around 20 Tesla. The dependence of the localization on the length and diameter of the nanotubes shows that the localization-delocalization transition can be observed for 2 nm diameter tube. The mechanism of the localization is explained in terms of the deformation-induced gauge field, which shows a topological nature of the localization. The transition from the delocalized states to the localized states can be observed by scanning tunneling microscopy and spectroscopy. A similarity between the transition and the spin Hall effect is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.3904v1.pdf"}
{"id": "0711.0650", "abstract": "  In this paper we study the role of surface plasmon modes in the Casimir effect. First we write the Casimir energy as a sum over the modes of a real cavity. We may identify two sorts of modes, two evanescent surface plasmon modes and propagative modes. As one of the surface plasmon modes becomes propagative for some choice of parameters we adopt an adiabatic mode definition where we follow this mode into the propagative sector and count it together with the surface plasmon contribution, calling this contribution \"plasmonic\". The remaining modes are propagative cavity modes, which we call \"photonic\". The Casimir energy contains two main contributions, one coming from the plasmonic, the other from the photonic modes. Surprisingly we find that the plasmonic contribution to the Casimir energy becomes repulsive for intermediate and large mirror separations. Alternatively, we discuss the common surface plasmon defintion, which includes only evanescent waves, where this effect is not found. We show that, in contrast to an intuitive expectation, for both definitions the Casimir energy is the sum of two very large contributions which nearly cancel each other. The contribution of surface plasmons to the Casimir energy plays a fundamental role not only at short but also at large distances. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.0650v1.pdf"}
{"id": "0711.0747", "abstract": "  Detecting the parity-odd, or B-mode, polarization pattern in the cosmic microwave background radiation due to primordial gravity waves is considered to be the final observational key to confirming the inflationary paradigm. The search for viable models of inflation from particle physics and string theory has (re)discovered another source for B-modes: cosmic strings. Strings naturally generate as much vector mode perturbation as they do scalar, producing B-mode polarization with a spectrum distinct from that expected from inflation itself. In a large set of models, B-modes arising from cosmic strings are more prominent than those expected from primordial gravity waves. In light of this, we study the physical underpinnings of string-sourced B-modes and the model dependence of the amplitude and shape of the C_l^BB power spectrum. Observational detection of a string-sourced B-mode spectrum would be a direct probe of post-inflationary physics near the GUT scale. Conversely, non-detection would put an upper limit on a possible cosmic string tension of Gμ< 10^-7 within the next three years. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.0747v3.pdf"}
{"id": "0711.1490", "abstract": "  The electron cloud effect (ECE) causes beam instabilities in accelerator structures with intense positively charged bunched beams. Reduction of the secondary electron yield (SEY) of the beam pipe inner wall is effective in controlling cloud formation. We summarize SEY results obtained from flat TiN, TiZrV and Al surfaces carried out in a laboratory environment. SEY was measured after thermal conditioning, as well as after low energy, less than 300 eV, particle exposure. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.1490v1.pdf"}
{"id": "0711.4585", "abstract": "  The dynamics of chaotic billiards is significantly influenced by coexisting regions of regular motion. Here we investigate the prevalence of a different fundamental structure, which is formed by marginally unstable periodic orbits and stands apart from the regular regions. We show that these structures both exist and strongly influence the dynamics of locally perturbed billiards, which include a large class of widely studied systems. We demonstrate the impact of these structures in the quantum regime using microwave experiments in annular billiards. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.4585v1.pdf"}
{"id": "0712.0813", "abstract": "  We describe a new, parallel programming version of the scalar field simulation program LATTICEEASY. The new C++ program, CLUSTEREASY, can simulate arbitrary scalar field models on distributed-memory clusters. The speed and memory requirements scale well with the number of processors. As with the serial version of LATTICEEASY, CLUSTEREASY can run simulations in one, two, or three dimensions, with or without expansion of the universe, with customizable parameters and output. The program and its full documentation are available on the LATTICEEASY website at http://www.science.smith.edu/departments/Physics/fstaff/gfelder/latticeeasy/. In this paper we provide a brief overview of what CLUSTEREASY does and the ways in which it does and doesn't differ from the serial version of LATTICEEASY. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0712/0712.0813v1.pdf"}
{"id": "0712.2682", "abstract": "  The problem of biclustering consists of the simultaneous clustering of rows and columns of a matrix such that each of the submatrices induced by a pair of row and column clusters is as uniform as possible. In this paper we approximate the optimal biclustering by applying one-way clustering algorithms independently on the rows and on the columns of the input matrix. We show that such a solution yields a worst-case approximation ratio of 1+sqrt(2) under L1-norm for 0-1 valued matrices, and of 2 under L2-norm for real valued matrices. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0712/0712.2682v2.pdf"}
{"id": "0712.3087", "abstract": "  We develop the real stabilization method within the framework of the relativistic mean field (RMF) model. With the self-consistent nuclear potentials from the RMF model, the real stabilization method is used to study single-particle resonant states in spherical nuclei. As examples, the energies, widths and wave functions of low-lying neutron resonant states in ^120Sn are obtained. These results are compared with those from the scattering phase shift method and the analytic continuation in the coupling constant approach and satisfactory agreements are found. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0712/0712.3087v1.pdf"}
{"id": "0712.3579", "abstract": "  We report an X-ray spectral study of the transverse structure of the Centaurus A jet using new data from the Chandra Cen A Very Large Project. We find that the spectrum steepens with increasing distance from the jet axis, and that this steepening can be attributed to a change in the average spectrum of the knotty emission. Such a trend is unexpected if the knots are predominantly a surface feature residing in a shear layer between faster and slower flows. We suggest that the spectral steepening of the knot emission as a function of distance from the jet axis is due to knot migration, implying a component of transverse motion of knots within the flow. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0712/0712.3579v1.pdf"}
{"id": "0801.0137", "abstract": "  We study a model of two layers, each consisting of a d-dimensional elastic object driven over a random substrate, and mutually interacting through a viscous coupling. For this model, the mean-field theory (i.e. a fully connected model) predicts a transition from elastic depinning to hysteretic plastic depinning as disorder or viscous coupling is increased. A functional RG analysis shows that any small inter-layer viscous coupling destablizes the standard (decoupled) elastic depinning FRG fixed point for d <= 4, while for d > 4 most aspects of the mean-field theory are recovered. A one-loop study at non-zero velocity indicates, for d<4, coexistence of a moving state and a pinned state below the elastic depinning threshold, with hysteretic plastic depinning for periodic and non-periodic driven layers. A 2-loop analysis of quasi-statics unveils the possibility of more subtle effects, including a new universality class for non-periodic objects. We also study the model in d=0, i.e. two coupled particles, and show that hysteresis does not always exist as the periodic steady state with coupled layers can be dynamically unstable. It is also proved that stable pinned configurations remain dynamically stable in presence of a viscous coupling in any dimension d. Moreover, the layer model for periodic objects is stable to an infinitesimal commensurate density coupling. Our work shows that a careful study of attractors in phase space and their basin of attraction is necessary to obtain a firm conclusion for dimensions d=1,2,3. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.0137v1.pdf"}
{"id": "0801.0420", "abstract": "  Quantum pumping holds great potential for future applications in micro- and nanotechnology. Its main feature, dissipationless charge transport, is theoretically possible via several different mechanisms. However, since no unambiguous verification has been demonstrated experimentally, the question of finding a viable mechanism for pumping remains open. Here we study quantum pumping in an one dimensional electron waveguide with a single time-dependent barrier. The quantum pumping of electrons using a potential barrier whose height and position are harmonically varied is analyzed analytically and by numerically solving the time-dependent Schrödinger equation. The pumped charge is modeled analytically by including two contributions in linear response theory. First, the scattering of electrons off a potential moving slowly through matter-waves gives a contribution independent of the translational velocity of the potential. Second, Doppler-shifted scattering events give rise to a velocity dependent contribution, which is found in general to be small in comparison with the first one. The relative phase between the oscillations of the height and position is found to be the factor that determines to what extent either contribution is present. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.0420v1.pdf"}
{"id": "0801.0766", "abstract": "  We study the relationship between different wave phenomena associated with a coronal mass ejection (CME) observed on 05 Mar. 2000. EIT waves were observed in the images recorded by EIT at 195 Å. The white-light LASCO/C2 images show clear deflection and propagation of a kink along with the CME. Spectroscopic observations recorded by the UVCS reveals excessive line broadening in the two O vi lines (1032 and 1037 Å). Moreover very hot lines such as Si xii and Mg x were observed. Interestingly, the EIT wave, the streamer deflection and the intensity modulation along the slit were all propagating North-East. Spatial and temporal correlations show that the streamer deflection and spectral line broadening are highly likely to be due to a CME-driven shock wave and that the EIT wave is the signature of a CME-driven shock wave in the lower corona. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.0766v1.pdf"}
{"id": "0801.1871", "abstract": "  Photons and electrons are the key quantum media for the quantum information processing based on solid state devices. The essential ingredients to accomplish the quantum repeater were investigated and their underlying physics were revealed. The relevant elementary processes of the quantum state transfer between a single photon and a single electron were analyzed, to clarify the conditions to be satisfied to achieve the high fidelity of the quantum state transfer. An optical method based on the Faraday rotation was proposed to carry out the Bell measurement of two electrons which is a key operation in the entanglement swapping for the quantum repeater and its feasibility was confirmed. Also investigated was the quantum dynamics in the electron-nuclei coupled spin system in quantum dots and a couple of new phenomena were predicted related to the correlations induced by the hyperfine interaction, namely, bunching and revival in the electron spin measurements. These findings will pave the way to accomplish the efficient and robust quantum repeater and nuclear spin quantum memory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.1871v1.pdf"}
{"id": "0801.2030", "abstract": "  The phase–space volume of regions of regular or trapped motion, for bounded or scattering systems with two degrees of freedom respectively, displays universal properties. In particular, sudden reductions in the phase-space volume or gaps are observed at specific values of the parameter which tunes the dynamics; these locations are approximated by the stability resonances. The latter are defined by a resonant condition on the stability exponents of a central linearly stable periodic orbit. We show that, for more than two degrees of freedom, these resonances can be excited opening up gaps, which effectively separate and reduce the regions of trapped motion in phase space. Using the scattering approach to narrow rings and a billiard system as example, we demonstrate that this mechanism yields rings with two or more components. Arcs are also obtained, specifically when an additional (mean-motion) resonance condition is met. We obtain a complete representation of the phase-space volume occupied by the regions of trapped motion. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.2030v2.pdf"}
{"id": "0801.2837", "abstract": "  We studied how the inhomogeneity of a sequence affects the phase transition that takes place at DNA melting. Unlike previous works, which considered thermodynamic quantities averaged over many different inhomogeneous sequences, we focused on precise sequences and investigated the succession of local openings that lead to their dissociation. For this purpose, we performed Transfer Integral type calculations with two different dynamical models, namely the heterogeneous Dauxois-Peyrard-Bishop model and the model based on finite stacking enthalpies we recently proposed. It appears that, for both models, the essential effect of heterogeneity is to let different portions of the investigated sequences open at slightly different temperatures. Besides this macroscopic effect, the local aperture of each portion indeed turns out to be very similar to that of a homogeneous sequence with the same length. Rounding of each local opening transition is therefore merely a size effect. For the Dauxois-Peyrard-Bishop model, sequences with a few thousands base pairs are still far from the thermodynamic limit, so that it is inappropriate, for this model, to discuss the order of the transition associated with each local opening. In contrast, sequences with several hundreds to a few thousands base pairs are pretty close to the thermodynamic limit for the model we proposed. The temperature interval where power laws holds is consequently broad enough to enable the estimation of critical exponents. On the basis of the few examples we investigated, it seems that, for our model, disorder does not necessarily induce a decrease of the order of the transition. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.2837v1.pdf"}
{"id": "0801.3082", "abstract": "  Cross sections and analyzing powers for proton elastic scattering from ^116,118,120,122,124Sn at 295 MeV have been measured for a momentum transfer of up to about 3.5 fm^-1 to deduce systematic changes of the neutron density distribution. We tuned the relativistic Love-Franey interaction to explain the proton elastic scattering of a nucleus whose density distribution is well known. Then, we applied this interaction to deduce the neutron density distributions of tin isotopes. The result of our analysis shows the clear systematic behavior of a gradual increase in the neutron skin thickness of tin isotopes with mass number. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.3082v2.pdf"}
{"id": "0801.3500", "abstract": "  Ab initio determination of model Hamiltonian parameters for strongly correlated materials is a key issue in applying many-particle theoretical tools to real narrow-band materials. We propose a self-contained calculation scheme to construct, with an ab initio approach, and solve such a Hamiltonian. The scheme uses a Wannier-function-basis set, with the Coulomb interaction parameter U obtained specifically for these Wannier functions via constrained Density functional theory (DFT) calculations. The Hamiltonian is solved by Dynamical Mean-Field Theory (DMFT) with the effective impurity problem treated by the Quantum Monte Carlo (QMC) method. Our scheme is based on the pseudopotential plane-wave method, which makes it suitable for developments addressing the challenging problem of crystal structural relaxations and transformations due to correlation effects. We have applied our scheme to the \"charge transfer insulator\" material nickel oxide and demonstrate a good agreement with the experimental photoemission spectra. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.3500v4.pdf"}
{"id": "0801.4930", "abstract": "  We propose a protocol for perfect quantum state transfer that is resilient to a broad class of realistic experimental imperfections, including noise sources that could be modelled either as independent Markovian baths or as certain forms of spatially correlated environments. We highlight interesting connections between the fidelity of state transfer and quantum stochastic resonance effects. The scheme is flexible enough to act as an effective entangling gate for the generation of genuine multipartite entanglement in a control-limited setting. Possible experimental implementations using superconducting qubits are also briefly discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.4930v2.pdf"}
{"id": "0802.1105", "abstract": "  We consider a Kuramoto model for the dynamics of an excitable system consisting of two coupled active rotators. Depending on both the coupling strength and the noise, the two rotators can be in a synchronized or desynchronized state. The synchronized state of the system is most stable for intermediate noise intensity in the sense that the coupling strength required to desynchronize the system is maximal at this noise level. We evaluate the phase boundary between synchronized and desynchronized states through numerical and analytical calculations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.1105v1.pdf"}
{"id": "0802.1297", "abstract": "  Dynamics of vortices in strongly type-II superconductors with strong disorder is investigated within the frustrated three-dimensional XY model. For two typical models in [Phys. Rev. Lett. 91, 077002 (2003)] and [Phys. Rev. B 68, 220502(R) (2003)], a strong evidence for the finite temperature vortex glass transition in the unscreened limit is provided by performing large-scale dynamical simulations. The obtained correlation length exponents and the dynamic exponents in both models are different from each other and from those in the three-dimensional gauge glass model. In addition, a genuine continuous depinning transition is observed at zero temperature for both models. A scaling analysis for the thermal rounding of the depinning transition shows a non-Arrhenius type creep motion in the vortex glass phase, contrarily to the recent studies.. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.1297v2.pdf"}
{"id": "0802.2498", "abstract": "  We analyse the phase diagram of ultra-cold bosons in a one-dimensional superlattice potential with disorder using the time evolving block decimation algorithm for infinite sized systems (iTEBD). For degenerate potential energies within the unit cell of the superlattice loophole-shaped insulating phases with non-integer filling emerge with a particle-hole gap proportional to the boson hopping. Adding a small amount of disorder destroys this gap. For not too large disorder the loophole Mott regions detach from the axis of vanishing hopping giving rise to insulating islands. Thus the system shows a transition from a compressible Bose-glass to a Mott-insulating phase with increasing hopping amplitude. We present a straight forward effective model for the dynamics within a unit cell which provides a simple explanation for the emergence of Mott-insulating islands. In particular it gives rather accurate predictions for the inner critical point of the Bose-glass to Mott-insulator transition. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.2498v1.pdf"}
{"id": "0802.2513", "abstract": "  We calculate the probability of recoilless emission and detection of neutrinos (Mossbauer effect with neutrinos) taking into account the boundedness of the parent and daughter nuclei in the neutrino source and detector as well as the leptonic mixing. We show that, in spite of their near monochromaticity, the recoillessly emitted and captured neutrinos oscillate. After a qualitative discussion of this issue, we corroborate and extend our results by computing the combined rate of ν̅_e production, propagation and detection in the framework of quantum field theory, starting from first principles. This allows us to avoid making any a priori assumptions about the energy and momentum of the intermediate-state neutrino. Our calculation permits quantitative predictions of the transition rate in future experiments, and shows that the decoherence and delocalization factors, which could in principle suppress neutrino oscillations, are irrelevant under realistic experimental conditions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.2513v2.pdf"}
{"id": "0802.4218", "abstract": "  We apply dynamical mean field theory to study a prototypical model that describes charge ordering in the presence of both electron-lattice interactions and intersite electrostatic repulsion between electrons. We calculate the optical and d.c. conductivity, and derive approximate formulas valid in the limiting electron-lattice coupling regimes. In the weak coupling regime, we recover the usual behavior of charge density waves, characterized by a transfer of spectral weight due to the opening of a gap in the excitation spectrum. In the opposite limit of very strong electron-lattice coupling, instead, the charge ordering transition is signaled by a global enhancement of the optical absorption, with no appreciable spectral weight transfer. Such behavior is related to the progressive suppression of thermally activated charge defects taking place below the critical temperature. At intermediate values of the coupling within the polaronic regime, a complex behavior is obtained where both mechanisms of transfer and enhancement of spectral weight coexist. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.4218v3.pdf"}
{"id": "0802.4246", "abstract": "  Manipulation of superpositions of discrete quantum states has a mathematical counterpart in the motion of a unit-length statevector in an N-dimensional Hilbert space. Any such statevector motion can be regarded as a succession of two-dimensional rotations. But the desired statevector change can also be treated as a succession of reflections, the generalization of Householder transformations. In multidimensional Hilbert space such reflection sequences offer more efficient procedures for statevector manipulation than do sequences of rotations. We here show how such reflections can be designed for a system with two degenerate levels - a generalization of the traditional two-state atom - that allows the construction of propagators for angular momentum states. We use the Morris-Shore transformation to express the propagator in terms of Morris-Shore basis states and Cayley-Klein parameters, which allows us to connect properties of laser pulses to Hilbert-space motion. Under suitable conditions on the couplings and the common detuning, the propagators within each set of degenerate states represent products of generalized Householder reflections, with orthogonal vectors. We propose physical realizations of this novel geometrical object with resonant, near-resonant and far-off-resonant laser pulses. We give several examples of implementations in real atoms or molecules. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.4246v1.pdf"}
{"id": "0802.4397", "abstract": "  We present an analysis of the spectral properties of the extragalactic radio sources in the nearly-complete VSA sample at 33GHz. Data from different surveys are used to study source spectra between 1.4 and 33GHz. We find that, in general, spectra can not be well described by a single power law in the range of frequencies considered. In particular, most of the VSA sources that are steep between 1.4 and 5GHz, show a spectral flattening at ν>5GHz. We identify 20 objects (19", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.4397v1.pdf"}
{"id": "0802.4415", "abstract": "  Multi-layered scintillating fibre arrays read-out are commonly used as high resolution charged particle hodoscopes. Fibres of a column along the geometrical trajectory of incident particles are typically grouped to one pixel of a multi-channel read-out device. In some applications the incident particles will cross the detection plane with large angles w.r.t. the normal to the layers. Then, the packing of the fibres needs to be adapted to the incident particles and the columns need to be inclined. In this paper possible fibre array geometries are shown, relevant design criteria for detectors are discussed, and the effect of diverging particles incident on fibre arrays was studied using a Monte Carlo simulation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.4415v1.pdf"}
{"id": "0803.0184", "abstract": "  Two body data alone cannot determine the potential uniquely, one needs three-body data as well. A method is presented here which simultaneously fits local or nonlocal potentials to two-body and three-body observables. The interaction of composite particles, due to the Pauli effect and the indistinguishability of the constituent particles, is genuinely nonlocal. As an example, we use a Pauli-correct nonlocal fish-bone type optical model for the α-α potential and derive the fitting parameters such that it reproduces the two-α and three-α experimental data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0803/0803.0184v2.pdf"}
{"id": "0803.0356", "abstract": "  In this paper, standard accretion disk models of AGNs are tested using light curves of 26 objects well observed for reverberation mapping. Time scales of variations are estimated by the most common definition of the variability time scale and the zero-crossing time of the autocorrelation function of the optical light curves for each source. The measured time scales of variations by the two methods are consistent with each other. If the typical value of the viscosity parameter α∼ 0.1 is adopted, the measured optical variability time scales are most close to the thermal time scales of the standard disks. If α is allowed to range from ∼ 0.03 to ∼ 0.2, the measured time scales are consistent with the thermal time scales of the standard disks. There is a linear relation between the measured variability time scales and black hole masses, and this linear relation is qualitatively consistent with expectation of the standard accretion disk models. The time lags measured by the ZDCF between different bands are on the order of days. The measured time lags of NGC 4151 and NGC 7469 are marginally consistent with the time lags estimated in the case of continuum thermal reprocessing for the standard accretion disk models. However, the measured time lags of NGC 5548 and Fairall 9 are unlikely to be the case of continuum thermal reprocessing. Our results are unlikely to be inconsistent with or are likely to be conditionally in favor of the standard accretion disk models of AGNs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0803/0803.0356v1.pdf"}
{"id": "0803.0871", "abstract": "  The spectral properties of type Ia supernovae in the ultraviolet (UV) are investigated using the early-time spectra of SN 2001ep and SN 2001eh obtained using the Hubble Space Telescope (HST). A series of spectral models is computed with a Monte Carlo spectral synthesis code, and the dependence of the UV flux on the elemental abundances and the density gradient in the outer layers of the ejecta is tested. A large fraction of the UV flux is formed by reverse fluorescence scattering of photons from red to blue wavelengths. This process, combined with ionization shifts due to enhanced line blocking, can lead to a stronger UV flux as the iron-group abundance in the outer layers is increased, contrary to previous claims. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0803/0803.0871v2.pdf"}
{"id": "0803.2020", "abstract": "  This work treats the matter deceleration in a magnetohydrodynamics radiative shock wave at the surface of a star. The problem is relevant to classical T Tauri stars where infalling matter is channeled along the star's magnetic field and stopped in the dense layers of photosphere. A significant new aspect of the present work is that the magnetic field has an arbitrary angle with respect to the normal to the star's surface. We consider the limit where the magnetic field at the surface of the star is not very strong in the sense that the inflow is super Alfvénic. In this limit the initial deceleration and heating of plasma (at the entrance to the cooling zone) occurs in a fast magnetohydrodynamic shock wave. To calculate the intensity of radiative losses we use \"real\" and \"power-law\" radiative functions. We determine the stability/instability of the radiative shock wave as a function of parameters of the incoming flow: velocity, strength of the magnetic field, and its inclination to the surface of the star. In a number of simulation runs with the \"real\" radiative function, we find a simple criterion for stability of the radiative shock wave. For a wide range of parameters, the periods of oscillation of the shock wave are of the order 0.02-0.2 sec. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0803/0803.2020v1.pdf"}
{"id": "0804.0297", "abstract": "  I discuss my recent attempt in search of a new framework for quantum field theory of D branes. After explaining some motivations in the background of this project, I present, as a first step towards our goal, a second-quantized reformulation of the U(N) Yang-Mills quantum mechanics in which the D0-brane creation-and-annihilation fields connecting theories with different N are introduced. Physical observables are expressed in terms of bilinear forms of the D0 fields. The large N limit is briefly treated using this new formalism. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0804/0804.0297v1.pdf"}
{"id": "0804.1069", "abstract": "  Using phase-referenced multi-epoch Very Long Baseline Array observations, we have measured the trigonometric parallax of several young stars in the Taurus and Ophiuchus star-forming regions with unprecedented accuracy. The mean distance to the Taurus complex was found to be about 140 pc, and its depth around 20 pc, comparable to the linear extent of Taurus on the plane of the sky. In Ophiuchus, 4 sources were observed so far. Two of them were found to be at about 160 pc (the distance traditionally attributed to Ophiuchus), while the other 2 are at about 120 pc. Since the entire Ophiuchus complex is only a few parsecs across, this difference is unlikely to reflect the depth of the region. Instead, we argue that two physically unrelated sites of star-formation are located along the line of sight toward Ophiuchus. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0804/0804.1069v1.pdf"}
{"id": "0804.2855", "abstract": "  Sgr A* is thought to be the radiative manifestation of a  3.6E6 Msun supermassive black hole at the Galactic center. Its mm/sub-mm spectrum and its flare emission at IR and X-ray wavelengths may be produced within the inner ten Schwarzschild radii of a hot, magnetized Keplerian flow. The lightcurve produced in this region may exhibit quasi-periodic variability. We present ray-tracing simulations to determine the general-relativistically modulated X-ray luminosity expected from plasma coupled magnetically to the rest of the disk as it spirals inwards below the innermost stable circular orbit towards the \"stress edge\" in the case of a Schwarzschild metric. The resulting lightcurve exhibits a modulation similar to that observed during a recent X-ray flare from Sgr A*. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0804/0804.2855v1.pdf"}
{"id": "0804.3599", "abstract": "  We present an approach to improving the precision of an initial document ranking wherein we utilize cluster information within a graph-based framework. The main idea is to perform re-ranking based on centrality within bipartite graphs of documents (on one side) and clusters (on the other side), on the premise that these are mutually reinforcing entities. Links between entities are created via consideration of language models induced from them.   We find that our cluster-document graphs give rise to much better retrieval performance than previously proposed document-only graphs do. For example, authority-based re-ranking of documents via a HITS-style cluster-based approach outperforms a previously-proposed PageRank-inspired algorithm applied to solely-document graphs. Moreover, we also show that computing authority scores for clusters constitutes an effective method for identifying clusters containing a large percentage of relevant documents. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0804/0804.3599v1.pdf"}
{"id": "0805.0147", "abstract": "  We study the spin dynamics of a long nanomagnet driven by an electrical current. In the case of only DC current, the spin dynamics has a sophisticated bifurcation diagram of attractors. One type of attractors is a weak chaos. On the other hand, in the case of only AC current, the spin dynamics has a rather simple bifurcation diagram of attractors. That is, for small Gilbert damping, when the AC current is below a critical value, the attractor is a limit cycle; above the critical value, the attractor is chaotic (turbulent). For normal Gilbert damping, the attractor is always a limit cycle in the physically interesting range of the AC current. We also developed a Melnikov integral theory for a theoretical prediction on the occurrence of chaos. Our Melnikov prediction seems performing quite well in the DC case. In the AC case, our Melnikov prediction seems predicting transient chaos. The sustained chaotic attractor seems to have extra support from parametric resonance leading to a turbulent state. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.0147v1.pdf"}
{"id": "0805.0172", "abstract": "  Many scaling relations are observed for self-gravitating systems in the universe. We explore the consistent understanding of them from a simple principle based on the proposal that the collision-less dark matter fluid terns into a turbulent state, i.e. dark turbulence, after crossing the caustic surface in the non-linear stage. The dark turbulence will not eddy dominant reflecting the collision-less property. After deriving Kolmogorov scaling laws from Navier-Stokes equation by the method similar to the one for Smoluchowski coagulation equation, we apply this to several observations such as the scale-dependent velocity dispersion, mass-luminosity ratio, magnetic fields, and mass-angular momentum relation, power spectrum of density fluctuations. They all point the concordant value for the constant energy flow per mass: 0.3 cm^2/sec^3, which may be understood as the speed of the hierarchical coalescence process in the cosmic structure formation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.0172v3.pdf"}
{"id": "0805.1098", "abstract": "  Electron acceleration mechanism at high Mach number collisionless shocks propagating in a weakly magnetized medium is investigated by a self-consistent two-dimensional particle-in-cell simulation. Simulation results show that strong electrostatic waves are excited via the electron-ion electrostatic two-stream instability at the leading edge of the shock transition region as in the case of earlier one-dimensional simulations. We observe strong electron acceleration that is associated with the turbulent electrostatic waves in the shock transition region. The electron energy spectrum in the shock transition region exhibits a clear power-law distribution with spectral index of 2.0  - 2.5. By analyzing the trajectories of accelerated electrons, we find that the acceleration mechanism is very similar to shock surfing acceleration of ions. In contrast to the ion shock surfing, however, the energetic electrons are reflected by electron-scale electrostatic fluctuations in the shock transition region, but not by the ion-scale cross-shock electrostatic potential. The reflected electrons are then accelerated by the convective electric field in front of the shock. We conclude that the multidimensional effects as well as the self-consistent shock structure are essential for the strong electron acceleration at high Mach number shocks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.1098v2.pdf"}
{"id": "0805.1393", "abstract": "  We study effects of nonmagnetic impurities in a spin-1/2 frustrated triangular antiferromagnet with the aim of understanding the observed broadening of ^13C NMR lines in the organic spin liquid material κ-(ET)_2Cu_2(CN)_3. For high temperatures down to J/3, we calculate local susceptibility near a nonmagnetic impurity and near a grain boundary for the nearest neighbor Heisenberg model in high temperature series expansion. We find that the local susceptibility decays to the uniform one in few lattice spacings, and for a low density of impurities we would not be able to explain the line broadening present in the experiments already at elevated temperatures. At low temperatures, we assume a gapless spin liquid with a Fermi surface of spinons. We calculate the local susceptibility in the mean field and also go beyond the mean field by Gutzwiller projection. The zero temperature local susceptibility decays as a power law and oscillates at 2 k_F. As in the high temperature analysis we find that a low density of impurities is not able to explain the observed broadening of the lines. We are thus led to conclude that there is more disorder in the system. We find that a large density of point-like disorder gives broadening that is consistent with the experiment down to about 5K, but that below this temperature additional mechanism is likely needed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.1393v1.pdf"}
{"id": "0805.1530", "abstract": "  We analyse scaling laws that govern macromolecules of different topology: polymer chains, homogeneous and miktoarm star polymers in a good solvent possibly constrained by a porous medium. The latter is modelled by long-range-correlated disorder with a pair correlation function g(r) that decays with a power law g(r) r^-a at large distances r. We show that this type of disorder changes the universality class of the system. Within the frames of the field-theoretical renormalization group approach we obtain the corresponding new universal critical exponents for systems of homogeneous and star copolymers and discuss different consequences of the architecture dependent change of the scaling behaviour. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.1530v1.pdf"}
{"id": "0805.1877", "abstract": "  Radio Frequency IDentification (RFID) systems are becoming more and more popular in the field of ubiquitous computing, in particular for objects identification. An RFID system is composed by one or more readers and a number of tags. One of the main issues in an RFID network is the fast and reliable identification of all tags in the reader range. The reader issues some queries, and tags properly answer. Then, the reader must identify the tags from such answers. This is crucial for most applications. Since the transmission medium is shared, the typical problem to be faced is a MAC-like one, i.e. to avoid or limit the number of tags transmission collisions. We propose a protocol which, under some assumptions about transmission techniques, always achieves a 100", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.1877v1.pdf"}
{"id": "0805.3128", "abstract": "  One-armed oscillation modes in the circumstellar discs of Be stars may explain the cyclical variations in their emission lines. We show that a three-dimensional effect, involving vertical motion and neglected in previous treatments, profoundly influences the dynamics. Using a secular theory of eccentric discs that reduces the problem to a second-order differential equation, we show that confined prograde modes are obtained for all reasonable disc temperatures and stellar rotation rates. We confirm these results using a numerical analysis of the full set of linearized equations for three-dimensional isothermal discs including viscous terms that couple the horizontal motions at different altitudes. In order to make these modes grow, viscous damping must be overcome by an excitation mechanism such as viscous overstability. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.3128v1.pdf"}
{"id": "0805.3322", "abstract": "  Complex networks are characterized by heterogeneous distributions of the degree of nodes, which produce a large diversification of the roles of the nodes within the network. Several centrality measures have been introduced to rank nodes based on their topological importance within a graph. Here we review and compare centrality measures based on spectral properties of graph matrices. We shall focus on PageRank, eigenvector centrality and the hub/authority scores of HITS. We derive simple relations between the measures and the (in)degree of the nodes, in some limits. We also compare the rankings obtained with different centrality measures. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.3322v2.pdf"}
{"id": "0805.3755", "abstract": "  We discuss various bifurcation problems in which two isolated periodic orbits exchange periodic “bridge” orbit(s) between two successive bifurcations. We propose normal forms which locally describe the corresponding fixed point scenarios on the Poincaré surface of section. Uniform approximations for the density of states for an integrable Hamiltonian system with two degrees of freedom are derived and successfully reproduce the numerical quantum-mechanical results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.3755v3.pdf"}
{"id": "0805.4259", "abstract": "  A notion of geometric symmetry is introduced that generalizes the classical concepts of Killing fields and other affine collineations. There is a sense in which flows under these new vector fields minimize deformations of the connection near a specified observer. Any exact affine collineations that may exist are special cases. The remaining vector fields can all be interpreted as analogs of Poincare and other well-known symmetries near timelike worldlines. Approximate conservation laws generated by these objects are discussed for both geodesics and extended matter distributions. One example is a generalized Komar integral that may be taken to define the linear and angular momenta of a spacetime volume as seen by a particular observer. This is evaluated explicitly for a gravitational plane wave spacetime. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.4259v2.pdf"}
{"id": "0806.0135", "abstract": "  We have reexamined the similarity solution for a self-gravitating isothermal gas sphere and examined implication to star formation in a turbulent cloud. When parameters are adequately chosen, the similarity solution expresses an accreting isothermal gas sphere bounded by a spherical shock wave. The mass and radius of the sphere increases in proportion to the time, while the central density decreases in proportion to the inverse square of time. The similarity solution is specified by the accretion rate and the infall velocity. The accretion rate has an upper limit for a given infall velocity. When the accretion rate is below the upper limit, there exist a pair of similarity solutions for a given set of the accretion rate and infall velocity. One of them is confirmed to be unstable against a spherical perturbation. This means that the gas sphere collapses to initiate star formation only when the accretion rate is larger than the upper limit. We have also examined stability of the similarity solution against non-spherical perturbation. Non-spherical perturbations are found to be damped. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0806/0806.0135v1.pdf"}
{"id": "0806.0405", "abstract": "  A clinical study was performed comparing the efficacy of multimedia learning modules with traditional textbooks for the first few topics of a calculus based introductory electricity and magnetism course. Students were randomly assigned to three different groups experiencing different presentations of the material; one group received the multimedia learning module presentations and the other two received the presentations via written text. All students were then tested on their learning immediately following the presentations as well as two weeks later. The students receiving the multimedia learning modules performed significantly better than the students experiencing the text-based presentations on both tests. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0806/0806.0405v1.pdf"}
{"id": "0806.0654", "abstract": "  The simplest decomposition of a Toffoli gate acting on three qubits requires five 2-qubit gates. If we restrict ourselves to controlled-sign (or controlled-NOT) gates this number climbs to six. We show that the number of controlled-sign gates required to implement a Toffoli gate can be reduced to just three if one of the three quantum systems has a third state that is accessible during the computation, i.e. is actually a qutrit. Such a requirement is not unreasonable or even atypical since we often artificially enforce a qubit structure on multilevel quantums systems (eg. atoms, photonic polarization and spatial modes). We explore the implementation of these techniques in optical quantum processing and show that linear optical circuits could operate with much higher probabilities of success. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0806/0806.0654v1.pdf"}
{"id": "0806.1530", "abstract": "  Red quasars are a population, characterized by significant extinction in UV, which could be explained by absorption of dusty gas on a scale of a few kpc. We show that the enhanced radiation-pressure drives the dusty gas to supersonically expand and produces shocks. The shocks energize electrons to be relativistic via the first Fermi acceleration. As a balance of shock acceleration and synchrotron emission and inverse Compton scattering, the maximum Lorentz factor of the electrons reaches as ∼ 10^6. The shocked interstellar medium appears as extended multiwavelength fuzz, in which synchrotron emission from the electrons peaks at near infrared or UV bands and inverse Compton scattering around 1.0GeV-0.1TeV. Future multiwavelength images of the fuzz would provide new clues to study the details of radiative feedback if red quasars could be a certain phase in evolutionary chains of galaxies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0806/0806.1530v1.pdf"}
{"id": "0806.3732", "abstract": "  We have calculated a series of models of outflows from the obscuring torus in active galactic nuclei (AGN). Our modeling assumes that the inner face of a rotationally supported torus is illuminated and heated by the intense X-rays from the inner accretion disk and black hole. As a result of such heating a strong biconical outflow is observed in our simulations. We calculate 3-dimensional hydrodynamical models, assuming axial symmetry, and including the effects of X-ray heating, ionization, and radiation pressure. We discuss the behavior of a large family of these models, their velocity fields, mass fluxes and temperature, as functions of the torus properties and X-ray flux. Synthetic warm absorber spectra are calculated, assuming pure absorption, for sample models at various inclination angles and observing times. We show that these models have mass fluxes and flow speeds which are comparable to those which have been inferred from observations of Seyfert 1 warm absorbers, and that they can produce rich absorption line spectra. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0806/0806.3732v1.pdf"}
{"id": "0807.0310", "abstract": "  We have investigated theoretically the conductance of a Normal-Superconductor point-contact in the tunnel limit and analyzed the quantum interference effects originating from the scattering of quasiparticles by point-like defects. Analytical expressions for the oscillatory dependence of the conductance on the position of the defect are obtained for the defect situated either in the normal metal, or in the superconductor. It is found that the amplitude of oscillations significantly increases when the applied bias approaches the gap energy of the superconductor. The spatial distribution of the order parameter near the surface in the presence of a defect is also obtained. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.0310v1.pdf"}
{"id": "0807.0495", "abstract": "  Time resolved spectra of β Cep yield the following average results: T_ eff =24000 ± 250 K, log g = 3.91 ± 0.05 and ξ = 8.1 ± 0.9 km s^-1. N, O, Ne, Al, Si and S abundances are solar while C, Mg and Fe are slightly under-abundant. Pulsational amplitudes of ΔT_ eff ∼ 700 K and Δlog g ∼ 0.2 dex are found from Hβ. The metal lines give similar amplitudes but centred on T_ eff ∼ 25000 K. An upper limit of 1.0 km s^-1 to the variability of the microturbulence is derived from the Si iii triplet at 455 nm. The radial velocity amplitude derived from the core of Hβ is ∼ 15", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.0495v1.pdf"}
{"id": "0807.0623", "abstract": "  Systematic search for multiperiodicity in the LMC Cepheids (Moskalik, Kolaczkowski     Mizerski 2004) has led to discovery of low amplitude nonradial modes in a substantial fraction of overtone pulsators. We present detailed discussion of this new type of multimode Cepheid pulsators and compare them to similar nonradial pulsators discovered among RR Lyrae stars. Finally, we show first detections of secondary nonradial modes in FU/FO double-mode Cepheids. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.0623v1.pdf"}
{"id": "0807.1706", "abstract": "  Prompted by high resolution observations, I propose an explanation for the 40+ year old problem of structure and energy balance in the solar transition region. The ingredients are simply cross-field diffusion of neutral atoms from cool threads extending into the corona, and the subsequent excitation, radiation and ionization of these atoms via electron impact. The processes occur whenever chromospheric plasma is adjacent to coronal plasma, and are efficient even when ion gyro-frequencies exceed collision frequencies. Cool threads - fibrils and spicules perhaps - grow slowly in thickness as a neutral, ionizing front expands across the magnetic field into coronal plasma. Radiative intensities estimated for H Lα are within an order of magnitude of those observed, with no ad-hoc parameters - only thermal parameters and geometric considerations are needed. I speculate that the subsequent dynamics of the diffused material might also explain observed properties of trace elements. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.1706v1.pdf"}
{"id": "0807.2792", "abstract": "  A detailed study is presented of the counterrotating model (CRM) for generic electrovacuum static axially symmetric relativistic thin disks without radial pressure. We find a general constraint over the counterrotating tangential velocities needed to cast the surface energy-momentum tensor of the disk as the superposition of two counterrotating charged dust fluids. We also find explicit expressions for the energy densities, charge densities and velocities of the counterrotating fluids. We then show that this constraint can be satisfied if we take the two counterrotating streams as circulating along electro-geodesics. However, we show that, in general, it is not possible to take the two counterrotating fluids as circulating along electro-geodesics nor take the two counterrotating tangential velocities as equal and opposite. Four simple families of models of counterrotating charged disks based on Chazy-Curzon-like, Zipoy-Voorhees-like, Bonnor-Sackfield-like and Kerr-like electrovacuum solutions are considered where we obtain some disks with a CRM well behaved. The models are constructed using the well-known “displace, cut and reflect” method extended to solutions of vacuum Einstein-Maxwell equations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.2792v1.pdf"}
{"id": "0807.2835", "abstract": "  We carried out extensive numerical orbit integrations to probe the long-term chaotic dynamics of the two strongest mean motion resonances of Neptune in the Kuiper belt, the 3:2 (Plutinos) and 2:1 (Twotinos). Our primary results include a computation of the relative volumes of phase space characterized by large- and small-resonance libration amplitudes, and maps of resonance stability measured by mean chaotic diffusion rate. We find that Neptune's 2:1 resonance has weaker overall long-term stability than the 3:2 – only  15", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.2835v3.pdf"}
{"id": "0807.3879", "abstract": "  We develop a new notion of security against timing attacks where the attacker is able to simultaneously observe the execution time of a program and the probability of the values of low variables. We then show how to measure the security of a program with respect to this notion via a computable estimate of the timing leakage and use this estimate for cost optimisation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.3879v1.pdf"}
{"id": "0807.4189", "abstract": "  We have used widely spaced in time Hubble Space Telescope images to determine tangential velocities of features associated with outflows from young stars. These observations were supplemented by groundbased telescope spectroscopy and from the resultant radial velocities, space velocities were determined for many outflows. Numerous new moving features were found and grouped into known and newly assigned Herbig Haro objects.   It was found that stellar outflow is highly discontinuous, as frequently is the case, with long-term gaps of a few hundred years and that these outflow periods are marked by staccato bursts over periods of about ten years. Although this has been observed in other regions, the Orion Nebula Cluster presents the richest display of this property.   Most of the large scale Herbig Haro objects in the brightest part of the Orion Nebula appear to originate from a small region northeast of the strong Orion-S radio and infrared sources. With the possible exception of HH 203, we are not able to identify specific stellar sources, but do identify candidate sources for several other bright Herbig Haro objects.   We find that there are optical features in the BN-KL region that can be related to the known large scale outflow that originates there. We find additional evidence for this outflow originating 500 to 1000 years ago. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.4189v1.pdf"}
{"id": "0808.1377", "abstract": "  We investigate the evolution of a central spin coupled to a spin bath without internal dynamics. We compare the cases where the bath couples to one or two components of the spin. It is found that the central spin dynamics is enhanced in the latter case, which may be interpreted as a frustration of dissipation. However, the quantum purity of the spin decays fast in both scenarios. We conclude that symmetric coupling of the bath to two orthogonal components of the spin inhibits dissipation but not decoherence. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.1377v1.pdf"}
{"id": "0808.2621", "abstract": "  We study the magnetization and the spin dynamics of the Cr_7Ni ring-shaped magnetic cluster. Measurements of the magnetization at high pulsed fields and low temperature are compared to calculations and show that the spin Hamiltonian approach provides a good description of Cr_7Ni magnetic molecule. In addition, the phonon-induced relaxation dynamics of molecular observables has been investigated. By assuming the spin-phonon coupling to take place through the modulation of the local crystal fields, it is possible to evaluate the decay of fluctuations of two generic molecular observables. The nuclear spin-lattice relaxation rate 1/T_1 directly probes such fluctuations, and allows to determine the magnetoelastic coupling strength. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.2621v1.pdf"}
{"id": "0809.0209", "abstract": "  Since that very memorable day at the Beijing 2008 Olympics, a big question on every sports commentator's mind has been \"What would the 100 meter dash world record have been, had Usain Bolt not celebrated at the end of his race?\" Glen Mills, Bolt's coach suggested at a recent press conference that the time could have been 9.52 seconds or better. We revisit this question by measuring Bolt's position as a function of time using footage of the run, and then extrapolate into the last two seconds based on two different assumptions. First, we conservatively assume that Bolt could have maintained Richard Thompson's, the runner-up, acceleration during the end of the race. Second, based on the race development prior to the celebration, we assume that he could also have kept an acceleration of 0.5 m/s^2 higher than Thompson. In these two cases, we find that the new world record would have been 9.61 +/- 0.04 and 9.55 +/- 0.04 seconds, respectively, where the uncertainties denote 95", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.0209v2.pdf"}
{"id": "0809.1442", "abstract": "  The analog of the Cachazo-Svrvcek-Witten rules for scattering amplitudes with massive quarks is derived following an approach previously employed for amplitudes with massive scalars. A prescription for the external wave-functions is given that leads to a one-to one relation between fields in the action and spin-states of massive quarks. Several examples for the application of the rules are given and the structure of some all-multiplicity amplitudes with a pair of massive quarks is discussed. The rules make supersymmetric relations to amplitudes with massive scalars manifest at the level of the action. The formalism is extended to several quark flavors with different masses. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.1442v2.pdf"}
{"id": "0809.1537", "abstract": "  A quantum neutral particle, constrained to move on a conical surface, is used as a toy model to explore bound states due to both a inverse squared distance potential and a δ-function potential, which appear naturally in the model. These pathological potentials are treated with the self-adjoint extension method which yields the correct boundary condition (not necessarily a null wavefunction) at the origin. We show that the usual boundary condition requiring that the wavefunction vanishes at the origin is arbitrary and drastically reduces the number of bound states if used. The situation studied here is closely related to the problem of a dipole moving in conical space. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.1537v1.pdf"}
{"id": "0809.2247", "abstract": "  A scheme is proposed to generate an entangled state between two (Lambda-type) four-level atoms that interact effectively by means of a detuned optical cavity and a laser beam that acts perpendicularly to the cavity axis. It is shown how the degree of entanglement for two atoms passing through the cavity can be controlled by manipulating their velocity and the (initial) distance between the atoms. In addition, three realistic schemes are suggested to implement the two-qubit gates within the framework of the suggested atom-cavity-laser setup, namely, the i-swap gate, controlled-Z gate and the controlled-NOT gate. For all these schemes, we analyze and discuss the atomic velocities and inter-atomic distances for which these gates are realized most reliably. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.2247v3.pdf"}
{"id": "0809.2262", "abstract": "  In this paper we present a comprehensive formalism for dilepton production from the collision of two polarized spin-12 hadrons by identifying the general angular distribution of the cross section in combination with a complete set of structure functions. The various structure functions are computed in the parton model approximation where we mainly consider the case when the transverse momentum of the dilepton pair is much smaller than its invariant mass. In this kinematical region dilepton production can be described in terms of transverse momentum dependent parton distributions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.2262v2.pdf"}
{"id": "0809.2638", "abstract": "  We have searched for pulsation of the anomalous X-ray pulsar (AXP) 4U 0142+61 in the K' band (λ_ eff = 2.11 μm) using the fast-readout mode of IRCS at the Subaru 8.2-m telescope. We found no significant signal at the pulse frequency expected by the precise ephemeris obtained by the X-ray monitoring observation with RXTE. Nonetheless, we obtained a best upper limit of 17", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.2638v1.pdf"}
{"id": "0809.3039", "abstract": "  We consider the gravitational recoil due to non-reflection-symmetric gravitational wave emission in the context of axisymmetric Robinson-Trautman spacetimes. We show that regular initial data evolve generically into a final configuration corresponding to a Schwarzschild black-hole moving with constant speed. For the case of (reflection-)symmetric initial configurations, the mass of the remnant black-hole and the total energy radiated away are completely determined by the initial data, allowing us to obtain analytical expressions for some recent numerical results that have been appeared in the literature. Moreover, by using the Galerkin spectral method to analyze the non-linear regime of the Robinson-Trautman equations, we show that the recoil velocity can be estimated with good accuracy from some asymmetry measures (namely the first odd moments) of the initial data. The extension for the non-axisymmetric case and the implications of our results for realistic situations involving head-on collision of two black holes are also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.3039v2.pdf"}
{"id": "0809.3144", "abstract": "  Possible existence of black holes remnants provides a suitable candidates for dark matter. In this paper we study the possibility of existence for such remnants. We consider quantum gravitational induced corrections of black hole's entropy and temperature to investigate the possibility of such relics. Observational scheme for detection of these remnants and their cosmological constraints are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.3144v1.pdf"}
{"id": "0809.3732", "abstract": "  We present theoretical study of morphology of Fe islands grown at Mo(110) surface in sub-monolayer MBE mode. We utilize atomistic SOS model with bond counting, and interactions of Fe adatom up to third nearest neighbors. We performed KMC simulations for different values of adatom interactions and varying temperatures. We have found that, while for the low temperature islands are fat fractals, for the temperature 500K islands have faceted rhombic-like shape. For the higher temperature, islands acquire a rounded shape. In order to evaluated qualitatively morphological changes, we measured averaged aspect ration of islands. We calculated dependence of the average aspect ratio on the temperature, and on the strength of interactions of an adatom with neighbors. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.3732v1.pdf"}
{"id": "0809.4186", "abstract": "  The Cryogenic Dark Matter Search experiment (CDMS) employs low-temperature Ge and Si detectors to detect WIMPs via their elastic scattering interaction with the target nuclei. The current analysis of 397.8 kg-days Ge exposure resulted in zero observed candidate events, setting an upper limit on the spin-independent WIMP-nucleon cross-section of 6.6 x 10^-44 cm^2 (4.6 x 10^-44 cm^2, when previous CDMS Soudan data is included) at the 90 ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.4186v1.pdf"}
{"id": "0809.5244", "abstract": "  We introduce a model of interacting Random Walk, whose hopping amplitude depends on the number of walkers/particles on the link. The mesoscopic counterpart of such a microscopic dynamics is a diffusing system whose diffusivity depends on the particle density. A non-equilibrium stationary flux can be induced by suitable boundary conditions, and we show indeed that it is mesoscopically described by a Fourier equation with a density dependent diffusivity. A simple mean-field description predicts a critical diffusivity if the hopping amplitude vanishes for a certain walker density. Actually, we evidence that, even if the density equals this pseudo-critical value, the system does not present any criticality but only a dynamical slowing down. This property is confirmed by the fact that, in spite of interaction, the particle distribution at equilibrium is simply described in terms of a product of Poissonians. For mesoscopic systems with a stationary flux, a very effect of interaction among particles consists in the amplification of fluctuations, which is especially relevant close to the pseudo-critical density. This agrees with analogous results obtained for Ising models, clarifying that larger fluctuations are induced by the dynamical slowing down and not by a genuine criticality. The consistency of this amplification effect with altered coloured noise in time series is also proved. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.5244v1.pdf"}
{"id": "0810.0231", "abstract": "  We examine and explain the spatial emission patterns of ultracold excited fermions in anisotropic trapping potentials in the presence of a spin polarised Fermi sea of ground state atoms. Due to the Pauli principle, the Fermi sea modifies the available phase space for the recoiling atom and thereby modifies its decay rate and the probability of the emitted photon's direction. We show that the spatial anisotropies are due to an intricate interplay between Fermi energies and degeneracy values of specific energy levels and identify a regime in which the emission will become completely directional. Our results are relevant for recent advances in trapping and manipulating cold fermionic samples experimentally and give an example of a conceptually new idea for a directional photon source. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.0231v1.pdf"}
{"id": "0810.0645", "abstract": "  We investigate canonical, phantom and quintom models, with the various fields being non-minimally coupled to gravity, in the framework of holographic dark energy. We classify them and we discuss their cosmological implications. In particular, we examine the present value of the dark energy equation-of-state parameter and the crossing through the phantom divide, and we extract the conditions for a future cosmological singularity. The combined scenarios are in agreement with observations and reveal interesting cosmological behaviors. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.0645v3.pdf"}
{"id": "0810.2838", "abstract": "  We propose a generalized Bell inequality for two three-dimensional systems with three settings in each local measurement. It is shown that this inequality is maximally violated if local measurements are configured to be mutually unbiased and a composite state is maximally entangled. This feature is similar to Clauser-Horne-Shimony-Holt inequality for two qubits but is in contrast with the two types of inequalities, Collins-Gisin-Linden-Massar-Popescu and Son-Lee-Kim, for high-dimensional systems. The generalization to aribitrary prime-dimensional systems is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.2838v1.pdf"}
{"id": "0810.3075", "abstract": "  We develop a renormalization group method to investigate synchronization clusters in a one-dimensional chain of nearest-neighbor coupled phase oscillators. The method is best suited for chains with strong disorder in the intrinsic frequencies and coupling strengths. The results are compared with numerical simulations of the chain dynamics and good agreement in several characteristics is found. We apply the renormalization group and simulations to Lorentzian distributions of intrinsic frequencies and couplings and investigate the statistics of the resultant cluster sizes and frequencies, as well as the dependence of the characteristic cluster length upon parameters of these Lorentzian distributions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.3075v2.pdf"}
{"id": "0810.4135", "abstract": "  A variety of intriguing polarization patterns are created when polarization observations of the single pulses from radio pulsars are displayed in a two-dimensional projection of the Poincare sphere. In many pulsars, the projections produce two clusters of data points that reside at antipodal points on the sphere. The clusters are formed by fluctuations in polarization amplitude that are parallel to the unit vectors representing the polarization states of the wave propagation modes in the pulsar magnetosphere. In other pulsars, however, the patterns are more complex, resembling annuli and bow ties or bars. The formation of these complex patterns is not understood and largely unexplored. An empirical model of pulsar polarization is used to show that these patterns arise from polarization fluctuations that are perpendicular to the mode vectors. The model also shows that the modulation index of the polarization amplitude is an indicator of polarization pattern complexity. A stochastic version of generalized Faraday rotation can cause the orientation of the polarization vectors to fluctuate and is a possible candidate for the perpendicular fluctuations incorporated in the model. Alternative models indicate that one mode experiences perpendicular fluctuations and the other does not, suggesting that the fluctuations could also be due to a mode-selective random process, such as scattering in the magnetosphere. A polarization stability analysis of the patterns implies that processes intrinsic to the emission are more effective in depolarizing the emission than fluctuations in the orientation of its polarization vector. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.4135v1.pdf"}
{"id": "0810.4155", "abstract": "  I use high resolution N-body/SPH simulations to model the new proper motion of the Large Magellanic Cloud (LMC) within the Milky Way (MW) halo and investigate the effects of gravitational and hydrodynamical forces on the formation of the Magellanic Stream (MS). Both the LMC and the MW are fully self consistent galaxy models embedded in extended cuspy LCDM dark matter halos. I find that ram-pressure from a low density ionized halo is sufficient to remove a large amount of gas from the LMC's disk forming a trailing Stream that extends more than 120 degrees from the Cloud. Tidal forces elongate the satellite's disk but do not affect its vertical structure. No stars become unbound showing that tidal stripping is almost effectiveless. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.4155v1.pdf"}
{"id": "0811.0836", "abstract": "  Diffusive shock acceleration operating at expanding supernova remnant shells is by far the most popular model for the origin of galactic cosmic rays. Despite the general consensus received by this model, an unambiguous and conclusive proof of the supernova remnant hypothesis is still missing. In this context, the recent developments in gamma ray astronomy provide us with precious insights into the problem of the origin of galactic cosmic rays, since production of gamma rays is expected both during the acceleration of cosmic rays at supernova remnant shocks and during their subsequent propagation in the interstellar medium. In particular, the recent detection of a number of supernova remnants at TeV energies nicely fits with the model, but it still does not constitute a conclusive proof of it, mainly due to the difficulty of disentangling the hadronic and leptonic contributions to the observed gamma ray emission. In this paper, the most relevant cosmic-ray-related results of gamma ray astronomy are briefly summarized, and the foreseeable contribution of future gamma ray observations to the final solution of the problem of cosmic ray origin is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.0836v1.pdf"}
{"id": "0811.1156", "abstract": "  Quantum Accelerator Modes were discovered in experiments with Kicked Cold Atoms in the presence of gravity. They were shown to be tightly related to resonances of the Quantum Kicked Rotor. In this paper a spinor formalism is developed for the analysis of Modes associatedwith resonances of arbitrary order q>1. Decoupling of spin variables from orbital ones is achieved by means of an ansatz of the Born-Oppenheimer type, that generates q independent band dynamics. Each of these is described, in classical terms, by a map, and the stable periodic orbits of this map give rise to quantum accelerator modes, which are potentially observable in experiments. The arithmetic organization of such periodic orbits is briefly discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.1156v1.pdf"}
{"id": "0811.1314", "abstract": "  In this work, we consider quasi-one-dimensional Bose-Einstein condensates (BECs), with spatially varying collisional interactions, trapped in double well potentials. In particular, we study a setup in which such a 'collisionally inhomogeneous' BEC has the same (attractive-attractive or repulsive-repulsive) or different (attractive-repulsive) type of interparticle interactions. Our analysis is based on the continuation of the symmetric ground state and anti-symmetric first excited state of the noninteracting (linear) limit into their nonlinear counterparts. The collisional inhomogeneity produces a saddle-node bifurcation scenario between two additional solution branches; as the inhomogeneity becomes stronger, the turning point of the saddle-node tends to infinity and eventually only the two original branches remain present, which is completely different from the standard double-well phenomenology. Finally, one of these branches changes its monotonicity as a function of the chemical potential, a feature especially prominent, when the sign of the nonlinearity changes between the two wells. Our theoretical predictions, are in excellent agreement with the numerical results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.1314v1.pdf"}
{"id": "0811.2032", "abstract": "  The Exterior-Interior duality expresses a deep connection between the Laplace spectrum in bounded and connected domains in ℝ^2, and the scattering matrices in the exterior of the domains. Here, this link is extended to the study of the spectrum of the discrete Laplacian on finite graphs. For this purpose, two methods are devised for associating scattering matrices to the graphs. The Exterior -Interior duality is derived for both methods. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.2032v1.pdf"}
{"id": "0811.2098", "abstract": "  Several applications require spatial distributions of the incident electric field that maximize the electric field at a focal point for a given input power. The field distributions are derived for various optical systems in a direct way based on fundamental physical properties. The results may prove useful for a wide range of applications, e.g., microscopy, scattering experiments or excitation of single atoms. For commonly used distributions - fundamental Gaussian modes and doughnut modes - we give the upper bounds of the achievable field amplitudes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.2098v3.pdf"}
{"id": "0811.2361", "abstract": "  The ARENA08 conference, held in Rome in June 2008, gave an almost complete overview on applications of the new techniques radio and acoustic detection of electromagnetic showers generated by high-energy cosmic particles in air or in dielectric media. There are vast activities all over the world, and the progress is remarkable. This was displayed by more than 30 contributions to the conference related to the radio detection technique, only. This paper gives a short summary on the status of 'radio detection of particles from the cosmos' as presented at the conference. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.2361v1.pdf"}
{"id": "0811.2508", "abstract": "  Brown dwarfs are natural clocks, cooling and dimming over time due to insufficient core fusion. They are also numerous and present in nearly all Galactic environments, making them potentially useful chronometers for a variety of Galactic studies. For this potential to be realized, however, precise and accurate ages for individual sources are required, a prospect made difficult by the complex atmospheres and spectra of low-temperature brown dwarfs; degeneracy between mass, age and luminosity; and the lack of useful age trends in magnetic activity and rotation. In this contribution, I review five ways in which ages for brown dwarfs are uniquely determined, discuss their applicability and limitations, and give current empirical precisions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.2508v1.pdf"}
{"id": "0811.2600", "abstract": "  We present a rigorous mathematical solution to photometric redshift estimation and the more general inversion problem. The challenge we address is to meaningfully constrain unknown properties of astronomical sources based on given observables, usually multicolor photometry, with the help of a training set that provides an empirical relation between the measurements and the desired quantities. We establish a formalism that blurs the boundary between the traditional empirical and template-fitting algorithms, as both are just special cases that are discussed in detail to put them in context. The new approach enables the development of more sophisticated methods that go beyond the classic techniques to combine their advantages. We look at the directions for further improvement in the methodology, and examine the technical aspects of practical implementations. We show how training sets are to be constructed and used consistently for reliable estimation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.2600v2.pdf"}
{"id": "0811.2737", "abstract": "  The interactions between linear elastic waves and a nonlinear crack with finite compressibility are studied in the one-dimensional context. Numerical studies on a hyperbolic model of contact with sinusoidal forcing have shown that the mean values of the scattered elastic displacements are discontinuous across the crack. The mean dilatation of the crack also increases with the amplitude of the forcing levels. The aim of the present theoretical study is to analyse these nonlinear processes under a larger range of nonlinear jump conditions. For this purpose, the problem is reduced to a nonlinear differential equation. The dependence of the periodic solution on the forcing amplitude is quantified under sinusoidal forcing conditions. Bounds for the mean, maximum and minimum values of the solution are presented. Lastly, periodic forcing with a null mean value is addressed. In that case, a result about the mean dilatation of the crack is obtained. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.2737v2.pdf"}
{"id": "0811.2789", "abstract": "  The Tail region of the Small Magellanic Cloud (SMC) was imaged using the MIPS instrument on the Spitzer Space Telescope as part of the SAGE-SMC Spitzer Legacy. Diffuse infrared emission from dust was detected in all the MIPS bands. The Tail gas-to-dust ratio was measured to be 1200 +/- 350 using the MIPS observations combined with existing IRAS and HI observations. This gas-to-dust ratio is higher than the expected 500-800 from the known Tail metallicity indicating possible destruction of dust grains. Two cluster regions in the Tail were resolved into multiple sources in the MIPS observations and local gas-to-dust ratios were measured to be  440 and  250 suggests dust formation and/or significant amounts of ionized gas in these regions. These results support the interpretation that the SMC Tail is a tidal tail recently stripped from the SMC that includes gas, dust, and young stars. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.2789v1.pdf"}
{"id": "0811.4279", "abstract": "  Although the flux density map of a bulk superconductor provides in principle sufficient information for calculating the magnitude and the direction of the supercurrent flow, the inversion of the Biot-Savart law is ill conditioned for thick samples, thus rendering this method unsuitable for state of the art bulk superconductors. If a thin (< 1 mm) slab is cut from the bulk, the inversion is reasonably well conditioned and the variation of the critical current density in the sample can be calculated with adequate spatial resolution. Therefore a novel procedure is employed, which exploits the symmetry of the problem and solves the equations non-iteratively, assuming a planar z-independent current density. The calculated current density at a certain position is found to depend on the magnetic induction. In this way the average field dependence of the critical current density Jc(B) is obtained also at low fields, which is not accessible to magnetisation measurements due to the self-field of the sample. It is further shown that an evaluation of magnetisation loops, taking the self-field into account, results in a similar dependence in the field range accessible to this experiment. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.4279v1.pdf"}
{"id": "0812.1020", "abstract": "  We estimate the sensitivity of various experiments detecting ultra-high-energy cosmic rays to primary photons with energies above 10^19 eV. We demonstrate that the energy of a primary photon may be significantly (up to a factor of   10) under- or overestimated for particular primary energies and arrival directions. We consider distortion of the reconstructed cosmic-ray spectrum for the photonic component. As an example, we use these results to constrain the parameter space of models of superheavy dark matter by means of both the observed spectra and available limits on the photon content. We find that a significant contribution of ultra-high-energy particles (photons and protons) from decays of superheavy dark matter is allowed by all these constraints. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.1020v2.pdf"}
{"id": "0812.1723", "abstract": "  We have studied the size dependence of the exciton g-factor in self-assembled InAs/InP quantum dots. Photoluminescence measurements on a large ensemble of these dots indicate a multimodal height distribution. Cross-sectional Scanning Tunneling Microscopy measurements have been performed and support the interpretation of the macro photoluminescence spectra. More than 160 individual quantum dots have systematically been investigated by analyzing single dot magneto-luminescence between 1200nm and 1600 nm. We demonstrate a strong dependence of the exciton g-factor on the height and diameter of the quantum dots, which eventually gives rise to a sign change of the g-factor. The observed correlation between exciton g-factor and the size of the dots is in good agreement with calculations. Moreover, we find a size dependent anisotropy splitting of the exciton emission in zero magnetic field. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.1723v1.pdf"}
{"id": "0812.2213", "abstract": "  In this paper we present a theoretical calculation of the acoustic Casimir pressure in a model micro system. Unlike the quantum case, the acoustic Casimir pressure can be made attractive or repulsive depending on the frequency bandwidth of the acoustic noise. As a case study, a one degree of freedom simple-lumped system in an acoustic resonant cavity is considered. We show that the frequency bandwidth of the acoustic field can be tuned to increase the stability in existing microswitch systems by selecting the sign of the force. The acoustic intensity and frequency bandwidth are introduced as two additional control parameters of the microswitch. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.2213v1.pdf"}
{"id": "0812.2565", "abstract": "  Coherent nuclear excitation in strongly laser-driven muonic atoms is calculated. The nuclear transition is caused by the time-dependent Coulomb field of the oscillating charge density of the bound muon. A closed-form analytical expression for electric multipole transitions is derived and applied to various isotopes; the excitation probabilities are in general very small. We compare the process with other nuclear excitation mechanisms through coupling with atomic shells and discuss the prospects to observe it in experiment. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.2565v1.pdf"}
{"id": "0812.2695", "abstract": "  We consider a thin superconducting film with a magnetic dot with permanent magnetization (normal to the film) placed on it by a method based on London-Maxwell equations. For sufficiently high dot magnetization a single vortex appears in the ground state. Further increase of magnetization is accompanied with the appearance of antivortices and more vortices in the film. We study analytically conditions for the appearance of a vortex–antivortex pair for a range of parameters. The phase diagram with diversity of vortex–antivortex states is calculated numerically. When appear in the ground state, antivortices are at distances comparable to the dot radius. For not too large dot radii the total vorticity in the ground state is predominantly zero or one. Magnetic field due to the dot and vortices everywhere in space is calculated analytically. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.2695v2.pdf"}
{"id": "0812.3143", "abstract": "  An algorithm for simulation of quantum many-body dynamics having su(2) spectrum-generating algebra is developed. The algorithm is based on the idea of dynamical coarse-graining. The original unitary dynamics of the target observables, the elements of the spectrum-generating algebra, is simulated by a surrogate open-system dynamics, which can be interpreted as weak measurement of the target observables, performed on the evolving system. The open-system state can be represented by a mixture of pure states, localized in the phase-space. The localization reduces the scaling of the computational resources with the Hilbert space dimension n by factor n^3/2/ln n compared to conventional sparse-matrix methods. The guidelines for the choice of parameters for the simulation are presented and the scaling of the computational resources with the Hilbert space dimension of the system is estimated. The algorithm is applied to the simulation of the dynamics of systems of 2*10^4 and 2*10^6 cold atoms in the double-well trap, described by the two-sites Bose-Hubbard model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.3143v2.pdf"}
{"id": "0812.3790", "abstract": "  The magnetorotational instability (MRI) plays an essential role in the formation of stars and black holes. By destabilizing hydrodynamically stable Keplerian flows, the MRI triggers turbulence and enables outward transport of angular momentum in accretion discs. We present the results of a liquid metal Taylor-Couette experiment under the influence of helical magnetic fields that show typical features of MRI at Reynolds numbers of the order 1000 and Hartmann numbers of the order 10. Particular focus is laid on an improved experiment in which split end caps are used to minimize the Ekman pumping. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.3790v1.pdf"}
{"id": "0812.4270", "abstract": "  Coronal mass ejections (CMEs) are solar eruptions into interplanetary space of as much as a few billion tons of plasma, with embedded magnetic fields from the Sun's corona. These perturbations play a very important role in solar–terrestrial relations, in particular in the spaceweather. In this work we present some preliminary results of the software development at the Universidad Nacional Autonoma de Mexico to perform Remote MHD Numerical Simulations. This is done to study the evolution of the CMEs in the interplanetary medium through a Web-based interface and the results are store into a database. The new astrophysical computational tool is called the Mexican Virtual Solar Observatory (MVSO) and is aimed to create theoretical models that may be helpful in the interpretation of observational solar data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.4270v1.pdf"}
{"id": "0901.0440", "abstract": "  We report on ab-initio calculations of the two-dimensional systems MoS2 and NbSe2, which recently were synthesized. We find that two-dimensional MoS_2 is a semiconductor with a gap which is rather close to that of the three dimensional analogue, and that NbSe_2 is a metal, which is similar to the three dimensional analogue of this compound.   We further computed the electronic structure of the two-dimensional hexagonal (graphene like) lattices of Si and Ge, and compare them with the electronic structure of graphene. It is found that the properties related to the Dirac cone do not appear in the case of two-dimensional hexagonal germanium, which is metallic, contrary to two-dimensional hexagonal silicon, which has an electronic structure very similar to the one of graphene, making them possibly equivalent. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.0440v1.pdf"}
{"id": "0901.0723", "abstract": "  We analyse new deep g and i-band imaging with the CFHT of 16 QSOs in the redshift range 0.9 to 1.3. The principal points of interest are the symmetry and signs of tidal effects in the QSO hosts and nearby (`companion') galaxies. The sample measures are compared with similar measures on randomly selected field galaxy samples. Asymmetry measures are made for all objects to g  22, and magnitudes of all galaxies 2 magnitudes fainter. The QSOs are found in denser environments than the field, and are somewhat offset from the centroid of their surrounding galaxies. The QSO hosts appear more disturbed than other galaxies. While the QSO companions and field galaxies have the same average asymmetry, the distribution of asymmetry values is different. QSO companions within 15 arcsec are fainter than average field galaxies. We discuss scenarios that are consistent with these and other measured quantities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.0723v1.pdf"}
{"id": "0901.0813", "abstract": "  Unstable modes growing when two plasma shells cross over a background plasma at arbitrary angle θ, are investigated using a non-relativistic three cold fluids model. Parallel flows with θ=0 are slightly more unstable than anti-parallel ones with θ=π. The case θ=π/2 is as unstable as the θ=0 one, but the fastest growing modes are oblique. While the most unstable wave vector varies with orientation, its growth rate slightly evolves and there is no such thing as a stable configuration. A number of exact results can be derived, especially for the θ=π/2 case. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.0813v1.pdf"}
{"id": "0901.1377", "abstract": "  We present an apparatus optimized for tracking swimming microorganisms in the size range 10-1000 microns, in three dimensions (3D), far from surfaces, and with negligible background convective fluid motion. CCD cameras attached to two long working distance microscopes synchronously image the sample from two perpendicular directions, with narrowband dark-field or bright-field illumination chosen to avoid triggering a phototactic response. The images from the two cameras can be combined to yield 3D tracks of the organism. Using additional, highly directional broad-spectrum illumination with millisecond timing control the phototactic trajectories in 3D of organisms ranging from Chlamydomonas to Volvox can be studied in detail. Surface-mediated hydrodynamic interactions can also be investigated without convective interference. Minimal modifications to the apparatus allow for studies of chemotaxis and other taxes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.1377v1.pdf"}
{"id": "0901.2661", "abstract": "  I will discuss the motivations for Neutrino Astronomy and its prospects given the current experimental scenario, which is the main focus of this paper. I will also go through the first results of the IceCube detector deep in the ice and of the ANTARES undersea telescope underlying complementary aspects, common and different challenges. It is an exciting time for this science since the first completed undersea detector is successfully taking data and the first cubic kilometer detector is going to be shortly more than half-way from its completion in Antarctica. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.2661v1.pdf"}
{"id": "0901.3177", "abstract": "  Coordinates, magnitudes and spectra are presented for 39 cataclysmic variables found in Sloan Digital Sky Survey spectra that were primarily obtained in 2006. Of these, 12 were CVs identified prior to the SDSS spectra (GY Cnc, GO Com, ST LMi, NY Ser, MR Ser, QW Ser, EU UMa, IY UMa, HS1340+1524, RXJ1610.1+0352, Boo 1, Leo 5). Follow-up spectroscopic observations of seven systems (including one from year 2005 and another from year 2004) were obtained, resulting in estimates of the orbital periods for 3 objects. The new CVs include two candidates for high inclination, eclipsing systems, 4 new Polars and three systems whose spectra clearly reveal atmospheric absorption lines from the underlying white dwarf. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.3177v1.pdf"}
{"id": "0901.3285", "abstract": "  We study s-wave pairing of population imbalanced Fermi atoms in quasi two dimensions using a mean field theory. At zero temperature, we map out the phase diagram in the entire Bardeen, Cooper and Schrieffer-Bose Einstein condensation (BCS-BEC) crossover region by investigating the effect of weak atom tunneling between layers. We find that the superfluid phase stabilizes as one decreases the atom tunneling between layers. This allows one to control the superfluid-normal first order phase transition by tuning a single experimental parameter. Further, we find that a tunneling induced polarized superfluid phase appears in a narrow parameter region in the BEC regime. At Finite temperatures, we use a Landau-Ginzberg functional approach to investigate the possibility of spatially inhomogeneous Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) phase in the weakly interacting BCS limit near the tricritical point of spatially homogenous superfluid, FFLO, and normal phases. We find that the normal-FFLO phase transition is first order transition as opposed to the continues transition predicted in zero temperature theories. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.3285v2.pdf"}
{"id": "0901.3934", "abstract": "  We propose a physically motivated and self-consistent prescription for the modeling of transient neutron star (NS) low-mass X-ray binary (LMXB) properties, such as duty cycle (DC), outburst duration and recurrence time. We apply this prescription to the population synthesis (PS) models of field LMXBs presented by Fragos et al. (2008), and compare the transient LMXB population to the Chandra X-ray survey of the two elliptical galaxies NGC 3379 and NGC 4278, which revealed several transient sources (Brassington et al., 2008, 2009). We are able to exclude models with a constant DC for all transient systems, while models with a variable DC based on the properties of each system are consistent with the observed transient populations. We predict that the majority of the observed transient sources in these two galaxies are LMXBs with red giant donors. Our comparison suggests that LMXBs formed through evolution of primordial field binaries are dominant in globular cluster (GC) poor elliptical galaxies, while they still have a significant contribution in GC rich ones. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.3934v1.pdf"}
{"id": "0902.1035", "abstract": "  The community of program optimisation and analysis, code performance evaluation, parallelisation and optimising compilation has published since many decades hundreds of research and engineering articles in major conferences and journals. These articles study efficient algorithms, strategies and techniques to accelerate programs execution times, or optimise other performance metrics (MIPS, code size, energy/power, MFLOPS, etc.). Many speedups are published, but nobody is able to reproduce them exactly. The non-reproducibility of our research results is a dark point of the art, and we cannot be qualified as computer scientists if we do not provide rigorous experimental methodology. This article provides a first effort towards a correct statistical protocol for analysing and measuring speedups. As we will see, some common mistakes are done by the community inside published articles, explaining part of the non-reproducibility of the results. Our current article is not sufficient by its own to deliver a complete experimental methodology, further efforts must be done by the community to decide about a common protocol for our future experiences. Anyway, our community should take care about the aspect of reproducibility of the results in the future. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.1035v8.pdf"}
{"id": "0902.1254", "abstract": "  We consider the problem of uniform sampling of points on an algebraic variety. Specifically, we develop a randomized algorithm that, given a small set of multivariate polynomials over a sufficiently large finite field, produces a common zero of the polynomials almost uniformly at random. The statistical distance between the output distribution of the algorithm and the uniform distribution on the set of common zeros is polynomially small in the field size, and the running time of the algorithm is polynomial in the description of the polynomials and their degrees provided that the number of the polynomials is a constant. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.1254v1.pdf"}
{"id": "0902.1926", "abstract": "  Surface plasmons are usually described as surface waves with either a complex wavevector or a complex frequency. When discussing their merits in terms of field confinment or enhancement of the local density of states, controversies regularly arise as the results depend on the choice of a complex wavevector or a complex frequency. In particular, the shape of the dispersion curves depends on this choice. When discussing diffraction of surface plasmon a scalar approximation is often used. In this work, we derive two equivalent vectorial representations of a surface plasmon field using an expansion over surface waves with either a complex wavevector or a complex frequency. These representations can be used to account for propagation and diffraction of surface waves. They can also be used to discuss the issue of field confinment and local density of states as they have a non-ambiguous relation with the two dispersion relations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.1926v1.pdf"}
{"id": "0902.3944", "abstract": "  This paper is concerned with the problem of Model Predictive Control and Rolling Horizon Control of discrete-time systems subject to possibly unbounded random noise inputs, while satisfying hard bounds on the control inputs. We use a nonlinear feedback policy with respect to noise measurements and show that the resulting mathematical program has a tractable convex solution in both cases. Moreover, under the assumption that the zero-input and zero-noise system is asymptotically stable, we show that the variance of the state, under the resulting Model Predictive Control and Rolling Horizon Control policies, is bounded. Finally, we provide some numerical examples on how certain matrices in the underlying mathematical program can be calculated off-line. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.3944v1.pdf"}
{"id": "0902.4872", "abstract": "  It has recently been suggested that the presence of multiple populations showing various amounts of helium enhancement is the rule, rather than the exception, among globular star clusters. An important prediction of this helium enhancement scenario is that the helium-enhanced blue horizontal branch (HB) stars should be brighter than the red HB stars which are not helium-enhanced. In this Letter, we test this prediction in the case of the Galactic globular cluster M3 (NGC 5272), for which the helium-enhancement scenario predicts helium enhancements of > 0.02 in virtually all blue HB stars. Using high-precision Stroemgren photometry and spectroscopic gravities for blue HB stars, we find that any helium enhancement among most of the cluster's blue HB stars is very likely less than 0.01, thus ruling out the much higher helium enhancements that have been proposed in the literature. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.4872v1.pdf"}
{"id": "0903.0844", "abstract": "  We present new radio and X-ray observations of Abell 262. The X-ray residual image provides the first evidence of an X-ray tunnel in this system while the radio data reveal that the central radio source is more than three times larger than previously known. We find that the well-known cluster-center S-shaped radio source B2 0149+35 is surrounded by extended emission to the east and south-west. The south-western extension is co-spatial with the X-ray tunnel seen in our new Chandra images while the eastern extension shows three clumps of emission with the innermost coincident with a faint X-ray cavity. The outer two eastern radio extensions are coincident with a newly detected X-ray depression. We use the projected separation of the emission regions to estimate a lower limit of tau_rep=28 Myr to the outburst repetition timescale of the central AGN. The total energy input into the cluster over multiple outburst episodes is estimated to be 2.2x 10^58 ergs, more than an order of magnitude larger than previously thought. The total AGN energy output determined from our new observations shows that the source should be capable of offsetting radiative cooling over several outburst episodes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.0844v1.pdf"}
{"id": "0903.0968", "abstract": "  Parametric excitation of a Bose-Einstein condensate (BEC) can be realized by periodically changing the interaction strength between the atoms. Above some threshold strength, this excitation modulates the condensate density. We show that when the condensate is trapped in a potential well of irregular shape, density waves can be strongly concentrated (\"scarred\") along the shortest periodic orbits of a classical particle moving within the confining potential. While single-particle wave functions of systems whose classical counterpart is chaotic may exhibit rich scarring patterns, in BEC, we show that nonlinear effects select mainly those scars that are locally described by stripes. Typically, these are the scars associated with self retracing periodic orbits that do not cross themselves in real space. Dephasing enhances this behavior by reducing the nonlocal effect of interference. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.0968v2.pdf"}
{"id": "0903.1253", "abstract": "  The steady state of a vibrated granular gas confined by a movable piston on the top is discussed. Particular attention is given to the hydrodynamic boundary conditions to be used when solving the inelastic Navier-Stokes equations. The relevance of an exact general condition relating the grain fluxes approaching and moving away from each of the walls is emphasized. It is shown how it can be used to get a consistent hydrodynamic description of the boundaries. The obtained expressions for the fields do not contain any undetermined parameter. Comparison of the theoretical predictions with molecular dynamics simulation results is carried out, and a good agreement is observed for low density and not too large inelasticity. A practical way of introducing small finite density corrections to the dilute limit theory is proposed, to improve the accuracy of the theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.1253v1.pdf"}
{"id": "0903.4165", "abstract": "  Over the last few years increasing consideration has been given to the study of Laser Guide Stars (LGS) for the measurement of the disturbance introduced by the atmosphere in optical and near-infrared astronomical observations from the ground. A possible method for the generation of a LGS is the excitation of the Sodium layer in the upper atmosphere at approximately 90 km of altitude. Since the Sodium layer is approximately 10 km thick, the artificial reference source looks elongated, especially when observed from the edge of a large aperture. The spot elongation strongly limits the performance of the most common wavefront sensors. The centroiding accuracy in a Shack-Hartmann wavefront sensor, for instance, decreases proportionally to the elongation (in a photon noise dominated regime). To compensate for this effect a straightforward solution is to increase the laser power, i.e. to increase the number of detected photons per subaperture. The scope of the work presented in this paper is twofold: an analysis of the performance of the Weighted Center of Gravity algorithm for centroiding with elongated spots and the determination of the required number of photons to achieve a certain average wavefront error over the telescope aperture. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.4165v1.pdf"}
{"id": "0903.5039", "abstract": "  Systems with long-range interactions display a short-time relaxation towards Quasi Stationary States (QSSs) whose lifetime increases with system size. The application of Lynden-Bell's theory of \"violent relaxation\" to the Hamiltonian Mean Field model leads to the prediction of out-of-equilibrium first and second order phase transitions between homogeneous (zero magnetization) and inhomogeneous (non-zero magnetization) QSSs, as well as an interesting phenomenon of phase re-entrances. We compare these theoretical predictions with direct N-body numerical simulations. We confirm the existence of phase re-entrance in the typical parameter range predicted from Lynden-Bell's theory, but also show that the picture is more complicated than initially thought. In particular, we exhibit the existence of secondary re-entrant phases: we find un-magnetized states in the theoretically magnetized region as well as persisting magnetized states in the theoretically unmagnetized region. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.5039v1.pdf"}
{"id": "0903.5301", "abstract": "  In this letter we present a study of the color magnitude relation of 468 early-type galaxies in the Virgo Cluster with Sloan Digital Sky Survey imaging data. The analysis of our homogeneous, model-independent data set reveals that, in all colors (u-g, g-r, g-i, i-z) similarly, giant and dwarf early-type galaxies follow a continuous color magnitude relation (CMR) that is best described by an S-shape. The magnitude range and quality of our data allows us to clearly confirm that the CMR in Virgo is not linear. Additionally, we analyze the scatter about the CMR and find that it increases in the intermediate-luminosity regime. Nevertheless, despite this observational distinction, we conclude from the similarly shaped CMR of semi-analytic model predictions that dwarfs and giants could be of the same origin. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.5301v2.pdf"}
{"id": "0903.5434", "abstract": "  Point source searches with neutrino telescopes like IceCube are normally restricted to one hemisphere, due to the selection of up-going events as a way of rejecting the atmospheric muon background. In this work we show that the down-going region above the horizon can be included in the search by suppressing the background through energy-sensitive selection procedures. This approach increases the reach to the EeV regime of the signal spectrum, which was previously not accessible due to the absorption of neutrinos with energies above a PeV inside the Earth. We present preliminary results of this analysis, which for the first time includes up-going as well as down-going muon events in a combined approach. We used data collected with IceCube in a configuration of 22 strings. No significant excess above the atmospheric background is observed. While other analyses provided results for the Northern hemisphere, this new approach extends the field of view to a large part of the Southern sky, which was previously not covered with IceCube. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.5434v1.pdf"}
{"id": "0904.0234", "abstract": "  The Lifshitz-type formulas for the free energy and Casimir-Polder force acting between an atom possessing a permanent magnetic moment and a wall made of different materials are derived. Simple model allowing analytic results is considered where the atomic magnetic susceptibility is frequency-independent and wall is made of ideal metal. Numerical computations of the Casimir-Polder force are performed for H atom interacting with walls made of ideal metal, nonmagnetic (Au) and ferromagnetic (Fe) metals and of ferromagnetic dielectric. It is shown that for the first three wall materials the inclusion of the magnetic moment of an atom decreases and for the fourth material increases the magnitude of the Casimir-Polder force. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0904/0904.0234v1.pdf"}
{"id": "0904.0600", "abstract": "  V440 Per is a Population I Cepheid with the period of 7.57 day and low amplitude, almost sinusoidal light and radial velocity curves. With no reliable data on the 1st harmonic, its pulsation mode identification remained controversial. We obtained a radial velocity curve of V440 Per with our new high precision and high throughput Poznan Spectroscopic Telescope. Our data reach the accuracy of 130 m/s per individual measurement and yield a secure detection of the 1st harmonic with the amplitude of A_2= 140+/- 15 m/s. The velocity Fourier phase ϕ_21 of V440 Per is inconsistent at the 7.25 σlevel with those of the fundamental mode Cepheids, implying that the star must be an overtone Cepheid, as originally proposed by Kienzle et al.(1999). Thus, V440 Per becomes the longest period Cepheid with the securely established overtone pulsations. We show, that the convective nonlinear pulsation hydrocode can reproduce the Fourier parameters of V440 Per very well. Requirement to match the observed properties of V440 Per constrains free parameters of the dynamical convection model used in the pulsation calculations, in particular the radiative losses parameter. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0904/0904.0600v1.pdf"}
{"id": "0904.1627", "abstract": "  We propose a kind of reaction-diffusion equations for cell differentiation, which exhibits the Turing instability. If the diffusivity of some variables is set to be infinity, we get coupled competitive reaction-diffusion equations with a global feedback term. The size ratio of each cell type is controlled by a system parameter in the model. Finally, we extend the model to a cascade model of cell differentiation. A hierarchical spatial structure appears as a result of the cell differentiation. The size ratio of each cell type is also controlled by the system parameter. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0904/0904.1627v1.pdf"}
{"id": "0905.0013", "abstract": "  The magnitude of the strong interaction is characterized by α_s, the coupling parameter in Quantum Chromodynamics (QCD), a parameter with an unexplained value in the Standard Model. In this paper, a candidate explanation for α_s is derived from (1) the lifetime of quark-antiquark pairs in vacuum fluctuations given by the Uncertainty Principle, (2) the variation of α_s as a function of energy in QCD, and (3) classical relativistic dynamics of the quarks and antiquarks. A semiclassical model for heavy quark-antiquark vacuum fluctuations is described herein, based on (2) and (3). The model in this paper predicts the measured value of α_s(M_Z^0) to be 0.121, which is in agreement with recent measurements within statistical uncertainties. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.0013v2.pdf"}
{"id": "0905.0791", "abstract": "  In this Letter, we present mean optical+NIR color gradient estimates for 5080 early-type galaxies (ETGs) in the grizYJHK wavebands of the Sloan Digital Sky Survey (SDSS) plus UKIRT Infrared Deep Sky Survey (UKIDSS). The color gradient is estimated as the logarithmic slope of the radial color profile in ETGs. With such a large sample size, we study the variation of the mean color gradient as a function of waveband with unprecedented accuracy. We find that (i) color gradients are mainly due, on average, to a metallicity variation of about -0.4dex per decade in galaxy radius; and (ii) a small, but significant, positive age gradient is present, on average, in ETGs, with the inner stellar population being slightly younger, by  0.1dex per radial decade, than the outer one. Also, we show that the presence of a positive mean age gradient in ETGs, as found in the present study, implies their effective radius to be smaller at high z, consistent with observations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.0791v1.pdf"}
{"id": "0905.2136", "abstract": "  The recent observations of the positron fraction in cosmic rays by PAMELA indicate that the fraction of positrons to the total electronic component in cosmic rays initially decreases in the energy region 1-10 GeV and increases thereafter. In this paper, we show that it is natural to expect such an increase of the positron fraction within the context of cosmic ray propagation models. It is shown that this ratio should reach an asymptotic value of  0.6 at very high energies. The specific measurements by PAMELA help us to distinguish amongst various models for cosmic ray propagation, and in particular, they support the nested leaky box model. They also provide, in conjunction with the observations of the total electronic component by HESS, FERMI, ATIC, and other experiments, a way of estimating the spectrum of electrons directly accelerated by discrete sources of cosmic rays in the Galaxy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.2136v2.pdf"}
{"id": "0905.2549", "abstract": "  Carbon-tetrafluoride (CF4) is used as a counting gas in particle detectors, but some of its properties that are of interest for large time-projection chambers are not well known. We measure the mean energy, which is proportional to the diffusion coefficent, and the attentuation coefficient of electron propagation in CF4 gas using a 10-liter dark matter detector prototype of the DMTPC project. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.2549v1.pdf"}
{"id": "0905.2793", "abstract": "  In recent works, we have proposed a stochastic cellular automaton model of traffic flow connecting two exactly solvable stochastic processes, i.e., the Asymmetric Simple Exclusion Process and the Zero Range Process, with an additional parameter. It is also regarded as an extended version of the Optimal Velocity model, and moreover it shows particularly notable properties. In this paper, we report that when taking Optimal Velocity function to be a step function, all of the flux-density graph (i.e. the fundamental diagram) can be estimated. We first find that the fundamental diagram consists of two line segments resembling an inversed-λ form, and next identify their end-points from a microscopic behaviour of vehicles. It is otable that by using a microscopic parameter which indicates a driver's sensitivity to the traffic situation, we give an explicit formula for the critical point at which a traffic jam phase arises. We also compare these analytical results with those of the Optimal Velocity model, and point out the crucial differences between them. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.2793v1.pdf"}
{"id": "0905.3836", "abstract": "  We use the measurement of gamma-ray burst (GRB) distances to constrain dark energy cosmological model parameters. We employ two methods for analyzing GRB data - fitting luminosity relation of GRBs in each cosmology and using distance measures computed from binned GRB data. Current GRB data alone cannot tightly constrain cosmological parameters and allow for a wide range of dark energy models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.3836v2.pdf"}
{"id": "0905.3951", "abstract": "  The increasing use of model-based tools enables further use of formal verification techniques in the context of distributed real-time systems. To avoid state explosion, it is necessary to construct verification models that focus on the aspects under consideration.   In this paper, we discuss how we construct a verification model for timing analysis in distributed real-time systems. We (1) give observations concerning restrictions of timed automata to model these systems, (2) formulate mathematical representations on how to perform model-to-model transformation to derive verification models from system models, and (3) propose some theoretical criteria how to reduce the model size. The latter is in particular important, as for the verification of complex systems, an efficient model reflecting the properties of the system under consideration is equally important to the verification algorithm itself. Finally, we present an extension of the model-based development tool FTOS, designed to develop fault-tolerant systems, to demonstrate ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.3951v3.pdf"}
{"id": "0905.4416", "abstract": "  Axion-like particles are an important part of the spectrum of anomalous gauge theories involving modified mechanisms of cancellation of the gauge anomalies. Among these are intersecting brane models, which are characterized by the presence of one physical axion. We overview a recent study of their supersymmetric construction and some LHC studies of the productions rates for a gauged axion. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.4416v1.pdf"}
{"id": "0906.0716", "abstract": "  It is shown that a real novel shares many characteristic features with a null model in which the words are randomly distributed throughout the text. Such a common feature is a certain translational invariance of the text. Another is that the functional form of the word-frequency distribution of a novel depends on the length of the text in the same way as the null model. This means that an approximate power-law tail ascribed to the data will have an exponent which changes with the size of the text-section which is analyzed. A further consequence is that a novel cannot be described by text-evolution models like the Simon model. The size-transformation of a novel is found to be well described by a specific Random Book Transformation. This size transformation in addition enables a more precise determination of the functional form of the word-frequency distribution. The implications of the results are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.0716v1.pdf"}
{"id": "0906.3005", "abstract": "  We performed a systematic study of the Doppler shifts and electron densities measured in an EUV bright point (hereafter BP) observed in more than 10 EUV lines with formation temperatures from log (T/K) p 4.5 to 6.3. Those parts of a BP seen in transition region and coronal lines are defined as its cool and hot components, respectively. We find that the transition from cool to hot occurs at a temperature around log (T/K) p 5.7. The two components of the BP reveal a totally different orientation and Doppler-shift pattern, which might result from a twist of the associated magnetic loop system. The analysis of magnetic field evolution and topology seems to favor a two-stage heating process, in which magnetic cancellation and separator reconnection are powering, respectively, the cool and hot components of the BP. We also found that the electron densities of both components of the BP are higher than those of the surrounding quiet Sun, and comparable to or smaller than active region densities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.3005v1.pdf"}
{"id": "0906.3064", "abstract": "  Performance of quantum process estimation is naturally limited to fundamental, random, and systematic imperfections in preparations and measurements. These imperfections may lead to considerable errors in the process reconstruction due to the fact that standard data analysis techniques presume ideal devices. Here, by utilizing generic auxiliary quantum or classical correlations, we provide a framework for estimation of quantum dynamics via a single measurement apparatus. By construction, this approach can be applied to quantum tomography schemes with calibrated faulty state generators and analyzers. Specifically, we present a generalization of \"Direct Characterization of Quantum Dynamics\" [M. Mohseni and D. A. Lidar, Phys. Rev. Lett. 97, 170501 (2006)] with an imperfect Bell-state analyzer. We demonstrate that, for several physically relevant noisy preparations and measurements, only classical correlations and small data processing overhead are sufficient to accomplish the full system identification. Furthermore, we provide the optimal input states for which the error amplification due to inversion on the measurement data is minimal. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.3064v1.pdf"}
{"id": "0906.3397", "abstract": "  The suppression of large transverse momentum hadrons in heavy-ion (A-A) collisions as compared to their scaled expectation from proton-proton collisions due to the interaction of hard partons with the hot and dense QCD medium in A-A collisions is experimentally a well established phenomenon. Focusing on leading hadrons produced in hard processes, the medium effect appears as energy loss. Beyond that, the question is how the lost energy is redistributed in the medium. With increased experimental statistics and most importantly the kinematic range of the LHC, studying the properties of full jets rather than leading hadrons is becoming feasible. On the theory side, analytic models and Monte-Carlo (MC) codes for in-medium shower evolution are being developed to describe jets in the medium. In this paper, expectations for medium-modified jet observables, the jet shapes, the thrust distribution and the n-jet fraction, are computed with the MC code YaJEM for various scenarios of the parton-medium interaction which all are consistent with high P_T hadron suppression data. The computation is done at 20 and 100 GeV jet energy, corresponding to probing typical RHIC and LHC kinematics, and the possibility to make an unbiased measurement of the observables is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.3397v2.pdf"}
{"id": "0906.3640", "abstract": "  We investigate, within N=4 SYM, the high energy behavior in the triple Regge limit of a six point correlator of R-currents. Using the leading logarithmic approximation, we sum all diagrams whose color lines fit onto the surface of a sphere. We find three distinct classes of graphs, and one of them contains the triple Pomeron vertex known from QCD. We present results which, within the AdS/CFT correspondence, can be compared with scattering amplitudes in the dual string theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.3640v1.pdf"}
{"id": "0906.4092", "abstract": "  The distribution of the returns for a stock are not well described by a normal probability density function (pdf). Student's t-distributions, which have fat tails, are known to fit the distributions of the returns. We present pricing of European call or put options using a log Student's t-distribution, which we call a Gosset approach in honour of W.S. Gosset, the author behind the nom de plume Student. The approach that we present can be used to price European options using other distributions and yields the Black-Scholes formula for returns described by a normal pdf. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.4092v1.pdf"}
{"id": "0906.5279", "abstract": "  We present an approach to simulating quantum computation based on a classical model that directly imitates discrete quantum systems. Qubits are represented as harmonic functions in a 2D vector space. Multiplication of qubit representations of different frequencies results in exponential growth of the state space similar to the tensor-product composition of qubit spaces in quantum mechanics. Individual qubits remain accessible in a composite system, which is represented as a complex function of a single variable, though entanglement imposes a demand on resources that scales exponentially with the number of entangled qubits. We carry out a simulation of Shor's algorithm and discuss a simpler implementation in this classical model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.5279v1.pdf"}
{"id": "0906.5332", "abstract": "  We derive an expression of the core traction contribution to the dislocation elastic energy within linear anisotropic elasticity theory using the sextic formalism. With this contribution, the elastic energy is a state variable consistent with the work of the Peach-Koehler forces. This contribution needs also to be considered when extracting from atomic simulations core energies. The core energies thus obtained are real intrinsic dislocation properties: they do not depend on the presence and position of other defects. This is illustrated by calculating core energies of edge dislocation in bcc iron, where we show that dislocations gliding in 110 planes are more stable than those gliding in 112 planes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.5332v1.pdf"}
{"id": "0907.0068", "abstract": "  Gravitational lensing allows us to probe the structure of matter on a broad range of astronomical scales, and as light from a distant source traverses an intervening galaxy, compact matter such as planets, stars, and black holes act as individual lenses. The magnification from such microlensing results in rapid brightness fluctuations which reveal not only the properties of the lensing masses, but also the surface brightness distribution in the source. However, while the combination of deflections due to individual stars is linear, the resulting magnifications are highly non-linear, leading to significant computational challenges which currently limit the range of problems which can be tackled. This paper presents a new and novel implementation of a numerical approach to gravitational microlensing, increasing the scale of the problems that can be tackled by more than two orders of magnitude, opening up a new regime of astrophysically interesting problems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.0068v1.pdf"}
{"id": "0907.0508", "abstract": "  In two-dimensional electron systems confined to wide AlAs quantum wells, composite fermions around the filling factor ν = 3/2 are fully spin polarized but possess a valley degree of freedom. Here we measure the energy needed to completely valley polarize these composite fermions as a function of electron density. Comparing our results to the existing theory, we find overall good quantitative agreement, but there is an unexpected trend: The measured composite fermion valley polarization energy, normalized to the Coulomb energy, decreases with decreasing density. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.0508v2.pdf"}
{"id": "0907.1241", "abstract": "  We study the influence of mutual interaction on the conformation of flexible poly(propyleneamine) dendrimers of fourth generation in concentrated solution. Mixtures of dendrimers with protonated and deuterated end groups are investigated by small-angle neutron scattering up to volume fractions of 0.23. This value is in the range of the overlap concentration of the dendrimers. The contrast between the solute and the solvent was varied by using mixtures of protonated and deuterated solvents. This allows us to investigate the partial structure factors of the deuterated dendrimers in detail. An analysis of the measured scattering intensities reveals that the shape of the flexible dendrimers is practically independent of the concentration in contrast to the pronounced conformational changes of flexible linear polymers. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.1241v1.pdf"}
{"id": "0907.1704", "abstract": "  While the energy of the universe has been established to be about 0.04 baryons, 0.24 dark matter and 0.72 dark energy, the cosmological entropy is almost entirely, about (1 - 10^-15), from black holes and only 10^-15 from everything else. This identification of all dark matter as black holes is natural in statistical mechanics. Cosmological history of dark matter is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.1704v1.pdf"}
{"id": "0907.2630", "abstract": "  We present a reanalysis of nonstandard neutrino-down-quark interactions of electron and tau neutrinos using solar, reactor and accelerator data. In addition updating the analysis by including new solar data from SNO phase III and Borexino, as well as new KamLAND data and solar fluxes, a key role is played in our analysis by the combination of these results with the CHARM data. The latter allows us to better constrain the axial and axial-vector electron and tau-neutrino nonstandard interaction parameters characterizing the deviations from the Standard Model predictions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.2630v3.pdf"}
{"id": "0907.3434", "abstract": "  In this work we consider the phase transition from ordered to disordered states that occur in the Vicsek model of self-propelled particles. This model was proposed to describe the emergence of collective order in swarming systems. When noise is added to the motion of the particles, the onset of collective order occurs through a dynamical phase transition. Based on their numerical results, Vicsek and his colleagues originally concluded that this phase transition was of second order (continuous). However, recent numerical evidence seems to indicate that the phase transition might be of first order (discontinuous), thus challenging Vicsek's original results. In this work we review the evidence supporting both aspects of this debate. We also show new numerical results indicating that the apparent discontinuity of the phase transition may in fact be a numerical artifact produced by the artificial periodicity of the boundary conditions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.3434v1.pdf"}
{"id": "0907.4519", "abstract": "  To investigate the formation and the propagation of relativistic shock waves in viscous gluon matter we solve the relativistic Riemann problem using a microscopic parton cascade. We demonstrate the transition from ideal to viscous shock waves by varying the shear viscosity to entropy density ratio η/s. We show that an η/s ratio larger than 0.2 prevents the development of well-defined shock waves on time scales typical for ultrarelativistic heavy-ion collisions. These findings are confirmed by viscous hydrodynamic calculations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.4519v2.pdf"}
{"id": "0907.4961", "abstract": "  We investigate front propagation and synchronization transitions in dependence on the information transmission delay and coupling strength over scale-free neuronal networks with different average degrees and scaling exponents. As the underlying model of neuronal dynamics, we use the efficient Rulkov map with additive noise. We show that increasing the coupling strength enhances synchronization monotonously, whereas delay plays a more subtle role. In particular, we found that depending on the inherent oscillation frequency of individual neurons, regions of irregular and regular propagating excitatory fronts appear intermittently as the delay increases. These delay-induced synchronization transitions manifest as well-expressed minima in the measure for spatial synchrony, appearing at every multiple of the oscillation frequency. Larger coupling strengths or average degrees can broaden the region of regular propagating fronts by a given information transmission delay and further improve synchronization. These results are robust against variations in system size, intensity of additive noise and the scaling exponent of the underlying scale-free topology. We argue that fine-tuned information transmission delays are vital for assuring optimally synchronized excitatory fronts on complex neuronal networks, and indeed, they should be seen as important as the coupling strength or the overall density of interneuronal connections. We finally discuss some biological implications of the presented results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.4961v1.pdf"}
{"id": "0908.1062", "abstract": "  Uncovering the community structure exhibited by real networks is a crucial step towards an understanding of complex systems that goes beyond the local organization of their constituents. Many algorithms have been proposed so far, but none of them has been subjected to strict tests to evaluate their performance. Most of the sporadic tests performed so far involved small networks with known community structure and/or artificial graphs with a simplified structure, which is very uncommon in real systems. Here we test several methods against a recently introduced class of benchmark graphs, with heterogeneous distributions of degree and community size. The methods are also tested against the benchmark by Girvan and Newman and on random graphs. As a result of our analysis, three recent algorithms introduced by Rosvall and Bergstrom, Blondel et al. and Ronhovde and Nussinov, respectively, have an excellent performance, with the additional advantage of low computational complexity, which enables one to analyze large systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0908/0908.1062v2.pdf"}
{"id": "0908.3370", "abstract": "  We study the global dynamics of advection-dominated accretion flows (ADAFs) with magnetically driven outflows. A fraction of gases in the accretion flow is accelerated into the outflows, which leads to decreasing of the mass accretion rate in the accretion flow towards the black hole. We find that the r-dependent mass accretion rate is close to a power-law one, m_dot r^s, as assumed in the advection-dominated inflow-outflow solution (ADIOS), in the outer region of the ADAF, while it deviates significantly from the power-law r-dependent accretion rate in the inner region of the ADAF. It is found that the structure of the ADAF is significantly changed in the presence of the outflows. The temperatures of the ions and electrons in the ADAF decreases in the presence of outflows, as a fraction of gravitational power released in the ADAF is tapped to accelerate the outflows. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0908/0908.3370v1.pdf"}
{"id": "0908.3952", "abstract": "  The coherence properties of a three-level Λ-system influenced by a Markovian environment are analyzed. A coherence vector formalism is used and a vector form of the Lindblad equation is derived. Together with decay channels from the upper state, open system channels acting on the subspace of the two lower states are investigated, i.e., depolarization, dephasing, and amplitude damping channels. We derive an analytic expression for the coherence vector and the concomitant optical susceptibility, and analyze how the different channels influence the optical response. This response depends non-trivially on the type of open system interaction present, and even gain can be obtained. We also present a geometrical visualization of the coherence vector as an aid to understand the system response. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0908/0908.3952v3.pdf"}
{"id": "0908.4261", "abstract": "  We use agent-based modeling to investigate the effect of conservatism and partisanship on the efficiency with which large populations solve the density classification task–a paradigmatic problem for information aggregation and consensus building. We find that conservative agents enhance the populations' ability to efficiently solve the density classification task despite large levels of noise in the system. In contrast, we find that the presence of even a small fraction of partisans holding the minority position will result in deadlock or a consensus on an incorrect answer. Our results provide a possible explanation for the emergence of conservatism and suggest that even low levels of partisanship can lead to significant social costs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0908/0908.4261v1.pdf"}
{"id": "0909.0214", "abstract": "  The dynamics of two-dimensional thin premixed flames is addressed in the framework of mathematical models where the flow field on either side of the front is piecewise incompressible and vorticity-free. Flames confined in channels with asymptotically-straight impenetrable walls are considered. Beside a few free propagations along straight channels, attention is focused on flames propagating against high-speed flows and positioned near a round central obstacle, or near two symmetric bumps protruding inward. Combining conformal maps and Green's functions, a regularised generalisation of Frankel's integro-differential equation for the instantaneous front shape in each configuration is derived, and solved numerically. This produces a variety of real looking phenomena: steady fronts (symmetric or not), noise-induced sub-wrinkles, flash-back events and breathing fronts in pulsating flows. Perspectives and open mathematical/physical problems are finally evoked. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.0214v2.pdf"}
{"id": "0909.2764", "abstract": "  We explicitly calculate the distance dependent correlation functions in a maximal entropy ensemble of random trees. We show that correlations remain disassortative at all distances and vanish only as a second inverse power of the distance. We discuss in detail the example of scale-free trees where the diverging second moment of the degree distribution leads to some interesting phenomena. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.2764v3.pdf"}
{"id": "0910.1618", "abstract": "  Flavor physics may help us understand theories beyond the standard model. In the context of supersymmetry, if we can measure the masses and mixings of sleptons and squarks, we may learn something about supersymmetry and supersymmetry breaking. Here we consider a hybrid gauge-gravity supersymmetric model in which the observed masses and mixings of the standard model leptons are explained by a U(1) x U(1) flavor symmetry. In the supersymmetric sector, the charged sleptons have reasonably large flavor mixings, and the lightest is metastable. As a result, supersymmetric events are characterized not by missing energy, but by heavy metastable charged particles. Many supersymmetric events are therefore fully reconstructible, and we can reconstruct most of the charged sleptons by working up the long supersymmetric decay chains. We obtain promising results for both masses and mixings, and conclude that, given a favorable model, precise measurements at the LHC may help shed light not only on new physics, but also on the standard model flavor parameters. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.1618v2.pdf"}
{"id": "0910.1715", "abstract": "  Nonperturbative analysis of quantum entanglement and quantum teleportation protocol using oscillator variables carried by observers in relativistic motion under the continuous influence of the environment is given. The full time evolution of quantum entanglement among static and accelerated observers is studied. The environment plays a dual role. While it creates bipartite and tripartite entanglement among observers even when the initial state is separable, it suppresses the entanglement via decoherence. Motivated by the black hole information problem, we consider quantum teleportation between static and accelerated observers. Acceleration of the observer suppresses fidelity of teleportation. Some of the quantum information escapes outside of the horizon in the form of bipartite and tripartite entanglement during the teleportation process. Explicit calculation of information loss is provided. In addition to the loss due to the interaction with the environment, there is an intrinsic loss originated in a measurement process. We discuss the implications of our results on the black hole case. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.1715v1.pdf"}
{"id": "0910.3454", "abstract": "  Using the Infrared Spectrograph aboard the Spitzer Space Telescope, we observed multiple epochs of 11 actively accreting T Tauri stars in the nearby Taurus-Auriga star forming region. In total, 88 low-resolution mid-infrared spectra were collected over 1.5 years in Cycles 2 and 3. The results of this multi-epoch survey show that the 10 um silicate complex in the spectra of two sources - DG Tau and XZ Tau - undergoes significant variations with the silicate feature growing both weaker and stronger over month- and year-long timescales. Shorter timescale variations on day- to week-long timescales were not detected within the measured flux errors. The time resolution coverage of this data set is inadequate for determining if the variations are periodic. Pure emission compositional models of the silicate complex in each epoch of the DG Tau and XZ Tau spectra provide poor fits to the observed silicate features. These results agree with those of previous groups that attempted to fit only single-epoch observations of these sources. Simple two-temperature, two-slab models with similar compositions successfully reproduce the observed variations in the silicate features. These models hint at a self-absorption origin of the diminution of the silicate complex instead of a compositional change in the population of emitting dust grains. We discuss several scenarios for producing such variability including disk shadowing, vertical mixing, variations in disk heating, and disk wind events associated with accretion outbursts. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.3454v1.pdf"}
{"id": "0910.5203", "abstract": "  By studying p-p collisions we hope to improve our understanding of the fundamental constituents of matter and how they form into colorless objects. Measurements of the inclusive jet cross-sections and fragmentation properties have confirmed that QCD based calculations give a good description of the hard scattering processes. However, as our analysis of jets has improved it has become clear that there is significant contribution to these measurements from processes other than those directly related to the initial hard scattering - the so-called underlying event. Several processes contribute to the underlying event, namely the beam-beam remnants, initial and final state radiation and multiple parton interactions. The structure of the jet and the underlying event are strikingly different in both their particle compositions and momentum distributions. Only by understanding both components can one fully describe a p-p collision. I will discuss preliminary results from studies of the underlying event in p-p collisions at sqrt(s) = 200 GeV at RHIC, and compare to PYTHIA predictions, as well as earlier results from the Tevatron at 1.8-1.96 TeV. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.5203v1.pdf"}
{"id": "0911.0711", "abstract": "  We investigate how the divergence-free property of magnetic fields can be exploited to resolve the azimuthal ambiguity present in solar vector magnetogram data, by using line-of-sight and horizontal heliographic derivative information as approximated from discrete measurements. Using synthetic data we test several methods that each make different assumptions about how the divergence-free property can be used to resolve the ambiguity. We find that the most robust algorithm involves the minimisation of the absolute value of the divergence summed over the entire field of view. Away from disk centre this method requires the sign and magnitude of the line-of-sight derivatives of all three components of the magnetic field vector. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0911/0911.0711v1.pdf"}
{"id": "0911.0853", "abstract": "  We describe three fundamentally different methods we have applied to calibrate the test mass displacement actuators to search for systematic errors in the calibration of the LIGO gravitational-wave detectors. The actuation frequencies tested range from 90 Hz to 1 kHz and the actuation amplitudes range from 1e-6 m to 1e-18 m. For each of the four test mass actuators measured, the weighted mean coefficient over all frequencies for each technique deviates from the average actuation coefficient for all three techniques by less than 4", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0911/0911.0853v1.pdf"}
{"id": "0911.1529", "abstract": "  This paper introduces Bohmian mechanics (BM) into the intense laser-atom physics to study high-order harmonic generation. In BM, the trajectories of atomic electrons in intense laser field can be obtained with the Bohm-Newton equation. The power spectrum with the trajectory of an atomic electron is calculated, which is found to be irregular. Next, the power spectrum associated with an atom ensemble from BM is considered, where the power spectrum becomes regular and consistent with that from quantum mechanics. Finally, the reason of the generation of the irregular spectrum is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0911/0911.1529v1.pdf"}
{"id": "0911.1531", "abstract": "  Variations of frequency separations of low-degree p-modes are studied over the solar activity cycle. The separations studied are obtained from the frequencies of low-degree p-modes of the Global Oscillation Network Group (GONG). 10.7 cm radio flux is used as an index of solar activity. Small separations of the p-mode frequencies are considered to be mainly dependent on the conditions in stellar interiors. Thus they could be applied to diagnose the changes in the stellar interior. Our calculation results show that the magnitudes of variations of the mean large separations are less than 1 σ over the solar activity cycle. Small separations show different behaviors in the ascending and descending phases of activity. In the ascending phase, variations of the small separations are less than 1 σ. However, the small separations have systematic shifts during 2004 - 2007. The shifts are roughly 1 σ or more. The variations of the ratios of the small to large separations with time are similar to the changes of the small separations. The effects of the changes in the large separations on the ratios are negligible. The variations of the separations may be a consequence of the influence from the surface activity or systematic errors in measurements or some processes taking place in the solar interior. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0911/0911.1531v1.pdf"}
{"id": "0911.3748", "abstract": "  We study critical properties of the relaxation time at a threshold point in switching processes between bistable states under change of external fields. In particular, we investigate the relaxation processes near the spinodal point of the infinitely long-range interaction model (the Husimi-Temperley model) by analyzing the scaling properties of the corresponding Fokker-Planck equation. We also confirm the obtained scaling relations by direct numerical solution of the original master equation, and by kinetic Monte Carlo simulation of the stochastic decay process. In particular, we study the asymptotic forms of the divergence of the relaxation time near the spinodal point, and reexamine its scaling properties. We further extend the analysis to transient critical phenomena such as a threshold behavior with diverging switching time under a general external driving perturbation. This models photo-excitation processes in spin-crossover materials. In the ongoing development of nano-size fabrication, such size-dependence of switching processes should be an important issue, and the properties obtained here will be applicable to a wide range of physical processes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0911/0911.3748v2.pdf"}
{"id": "0911.5628", "abstract": "  This paper develops a method for estimating parameters of a vector autoregression (VAR) observed in white noise. The estimation method assumes the noise variance matrix is known and does not require any iterative process. This study provides consistent estimators and shows the asymptotic distribution of the parameters required for conducting tests of Granger causality. Methods in the existing statistical literature cannot be used for testing Granger causality, since under the null hypothesis the model becomes unidentifiable. Measurement error effects on parameter estimates were evaluated by using computational simulations. The results show that the proposed approach produces empirical false positive rates close to the adopted nominal level (even for small samples) and has a good performance around the null hypothesis. The applicability and usefulness of the proposed approach are illustrated using a functional magnetic resonance imaging dataset. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0911/0911.5628v1.pdf"}
{"id": "0912.0090", "abstract": "  We examine the transformation of particle trajectories in models with deformations of Special Relativity that have an energy-dependent and observer-independent speed of light. These transformations necessarily imply that the notion of what constitutes the same space-time event becomes dependent on the observer's inertial frame. To preserve observer-independence, the such arising nonlocality should not be in conflict with our knowledge of particle interactions. This requirement allows us to derive strong bounds on deformations of Special Relativity and rule out a modification to first order in energy over the Planck mass. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0912/0912.0090v1.pdf"}
{"id": "0912.0547", "abstract": "  We have mapped the Dirac point in exfoliated monolayer and bilayer graphene using spatially resolved scanning tunneling spectroscopy (STS) measurements at low temperature. The Dirac point shifts in energy at different locations in graphene. However, a cross correlation with the topography shows no correlation indicating that topographic features such as ripples are not the primary source of the variation. Rather, we attribute the shift of the Dirac point to random charged impurities located near the graphene. Our findings emphasize the need to advance exfoliated graphene sample preparation to minimize the effect of impurities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0912/0912.0547v1.pdf"}
{"id": "0912.3464", "abstract": "  We present a quantitative measure of physical complexity, based on the amount of information required to build a given physical structure through self-assembly. Our procedure can be adapted to any given geometry, and thus to any given type of physical system. We illustrate our approach using self-assembling polyominoes, and demonstrate the breadth of its potential applications by quantifying the physical complexity of molecules and protein complexes. This measure is particularly well suited for the detection of symmetry and modularity in the underlying structure, and allows for a quantitative definition of structural modularity. Furthermore we use our approach to show that symmetric and modular structures are favoured in biological self-assembly, for example of protein complexes. Lastly, we also introduce the notions of joint, mutual and conditional complexity, which provide a useful distance measure between physical structures. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0912/0912.3464v2.pdf"}
{"id": "0912.3596", "abstract": "  We revisit the vertical structure of neutrino-dominated accretion flows in spherical coordinates. We stress that the flow should be geometrically thick when advection becomes dominant. In our calculation, the luminosity of neutrino annihilation is enhanced by one or two orders of magnitude. The empty funnel along the rotation axis can naturally explain the neutrino annihilable ejection. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0912/0912.3596v1.pdf"}
{"id": "0912.4490", "abstract": "  Many of the most exciting questions in astrophysics and cosmology, including the majority of observational probes of dark energy, rely on an understanding of the nonlinear regime of structure formation. In order to fully exploit the information available from this regime and to extract cosmological constraints, accurate theoretical predictions are needed. Currently such predictions can only be obtained from costly, precision numerical simulations. This paper is the third in a series aimed at constructing an accurate calibration of the nonlinear mass power spectrum on Mpc scales for a wide range of currently viable cosmological models, including dark energy. The first two papers addressed the numerical challenges, and the scheme by which an interpolator was built from a carefully chosen set of cosmological models. In this paper we introduce the \"Coyote Univers\"' simulation suite which comprises nearly 1,000 N-body simulations at different force and mass resolutions, spanning 38 wCDM cosmologies. This large simulation suite enables us to construct a prediction scheme, or emulator, for the nonlinear matter power spectrum accurate at the percent level out to k 1 h/Mpc. We describe the construction of the emulator, explain the tests performed to ensure its accuracy, and discuss how the central ideas may be extended to a wider range of cosmological models and applications. A power spectrum emulator code is released publicly as part of this paper. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0912/0912.4490v3.pdf"}
{"id": "1001.0512", "abstract": "  We present high-resolution, high signal-to-noise UVES spectra of AO Vel, a quadruple system containing an eclipsing BpSi star. From these observations we reconstruct the spectra of the individual components and perform an abundance analysis of all four stellar members. We found that all components are chemically peculiar with different abundances patters. In particular, the two less massive stars show typical characteristics of HgMn stars. The two most massive stars in the system show variable line profiles indicating the presence of chemical spots. Given the youth of the system and the notable chemical peculiarities of their components, this system could give important insights in the origin of chemical anomalies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1001/1001.0512v1.pdf"}
{"id": "1001.1537", "abstract": "  The Virtual Observatory has reached sufficient maturity for its routine scientific exploitation by astronomers. To prove this statement, here I present a brief description of the complete VO-powered PhD thesis entitled \"Galactic and extragalactic research with modern surveys and the Virtual Observatory\" comprising 4 science cases covering various aspects of astrophysical research. These comprize: (1) homogeneous search and measurement of main physical parameters of Galactic open star clusters in huge multi-band photometric surveys; (2) study of optical-to-NIR galaxy colors using a large homogeneous dataset including spectroscopy and photometry from SDSS and UKIDSS; (3) study of faint low-mass X-ray binary population in modern observational archives; (4) search for optical counterparts of unidentified X-ray objects with large positional uncertainties in the Galactic Plane. All these projects make heavy use of the VO technologies and tools and would not be achievable without them. So refereed papers published in the frame of this thesis can undoubtedly be added to the growing list of VO-based research works. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1001/1001.1537v1.pdf"}
{"id": "1001.2724", "abstract": "  Particle induced X-ray emission (PIXE) is a physical effect that is not yet adequately modelled in Geant4. The current status as in Geant4 9.2 release is reviewed and new developments are described. The capabilities of the software prototype are illustrated in application to the shielding of the X-ray detectors of the eROSITA telescope on the upcoming Spectrum-X-Gamma space mission. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1001/1001.2724v1.pdf"}
{"id": "1001.2843", "abstract": "  The International X-ray Observatory (IXO) is a joint ESA-JAXA-NASA effort to address fundamental and timely questions in astrophysics: What happens close to a black hole? How did supermassive black holes grow? How does large scale structure form? What is the connection between these processes? To address these questions IXO will employ optics with 3 sq m collecting area and 5 arc sec angular resolution - 20 times more collecting area at 1 keV than any previous X-ray observatory. Focal plane instruments will deliver a 100-fold increase in effective area for high-resolution spectroscopy, deep spectral imaging over a wide field of view, unprecedented polarimetric sensitivity, microsecond spectroscopic timing, and high count rate capability. The mission is being planned for launch in 2021 to an L2 orbit, with a five-year lifetime and consumables for 10 years. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1001/1001.2843v1.pdf"}
{"id": "1001.2898", "abstract": "  The New Muon (g-2) Collaboration at Fermilab has proposed to measure the anomalous magnetic moment of the muon, a_μ, a factor of four better than was done in E821 at the Brookhaven AGS, which obtained a_μ = [116 592 089 (63)] × 10^-11 ± 0.54 ppm. The last digit of a_μ is changed from the published value owing to a new value of the ratio of the muon-to-proton magnetic moment that has become available. At present there appears to be a difference between the Standard-Model value and the measured value, at the ≃ 3 standard deviation level when electron-positron annihilation data are used to determine the lowest-order hadronic piece of the Standard Model contribution. The improved experiment, along with further advances in the determination of the hadronic contribution, should clarify this difference. Because of its ability to constrain the interpretation of discoveries made at the LHC, the improved measurement will be of significant value, whatever discoveries may come from the LHC. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1001/1001.2898v2.pdf"}
{"id": "1001.3806", "abstract": "  Quarkonia and B-Physics are among the first areas to be investigated with the first data collected by ATLAS. The ATLAS detector at CERN's LHC is preparing to take data from proton-proton collisions expected to start by the end of 2009. Investigation of the decay of B-hadrons represents a complementary approach to direct searches for Physics beyond the Standard Model. Early B-physics data will provide valuable information on the detector performance, as well as allow calibration studies in support of new Physics searches. Meaningful quarkonia studies performed with early data are expected to have the reach to make authoritative statements about the underlying production mechanism and provide cross-sections in this new energy regime. We review various aspects of prompt quarkonium production at the LHC: the accessible ranges in transverse momentum and pseudo-rapidity, spin alignment of vector states, separation of color octet and color singlet production mechanism and feasibility of observing radiative chi_c decays ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1001/1001.3806v1.pdf"}
{"id": "1002.1529", "abstract": "  In this paper we discuss design concepts for increasing the spatial resolution, improving the sensitivity, and reducing the invasiveness in scanning Superconducting Quantum Interference Device (SQUID) microscope sensors with integrated flux pickup loops. This can be done not only by reducing the ground-rule line widths and spacings, but also by taking advantage of planarization, reducing flux noise through reducing the SQUID inductance, and reducing back-action through dispersive readouts or on-chip filtering. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.1529v1.pdf"}
{"id": "1002.1710", "abstract": "  We revisit the dynamical equivalence between different representations of vacuum modified gravity models in view of Legendre transformations. The equivalence is discussed for both bulk and boundary space, by including in our analysis the relevant Gibbons-Hawking terms. In the f(R) case, the Legendre transformed action coincides with the usual Einstein frame one. We then re-express the R+f(G) action, where G is the Gauss-Bonnet term, as a second order theory with a new set of field variables, four tensor fields and one scalar and study its dynamics. For completeness, we also calculate the conformal transformation of the full Jordan frame R+f(G) action. All the appropriate Gibbons-Hawking terms are calculated explicitly. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.1710v3.pdf"}
{"id": "1002.2171", "abstract": "  Using virtual stock markets with artificial interacting software investors, aka agent-based models (ABMs), we present a method to reverse engineer real-world financial time series. We model financial markets as made of a large number of interacting boundedly rational agents. By optimizing the similarity between the actual data and that generated by the reconstructed virtual stock market, we obtain parameters and strategies, which reveal some of the inner workings of the target stock market. We validate our approach by out-of-sample predictions of directional moves of the Nasdaq Composite Index. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.2171v1.pdf"}
{"id": "1002.2567", "abstract": "  Chromospheric activity has been thought to decay smoothly with time and, hence, to be a viable age indicator. Measurements in solar type stars in open clusters seem to point to a different conclusion: chromospheric activity undergoes a fast transition from Hyades level to that of the Sun after about 1 Gyr of main–sequence lifetime and any decaying trend before or after this transition must be much less significant than the short term variations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.2567v2.pdf"}
{"id": "1002.2728", "abstract": "  We study all known and as yet unknown forces between two neutral atoms, modeled as three dimensional harmonic oscillators, arising from mutual influences mediated by an electromagnetic field but not from their direct interactions. We allow as dynamical variables the center of mass motion of the atom, its internal degrees of freedom and the quantum field treated relativistically. We adopt the method of nonequilibrium quantum field theory which can provide a first principle, systematic and unified description including the intrinsic field fluctuations and induced dipole fluctuations. The inclusion of self-consistent back-actions makes possible a fully dynamical description of these forces valid for general atom motion. In thermal equilibrium we recover the known forces – London, van der Waals and Casimir-Polder forces – between neutral atoms in the long-time limit but also discover the existence of two new types of interatomic forces. The first, a `nonequilibrium force', arises when the field and atoms are not in thermal equilibrium, and the second, which we call an `entanglement force', originates from the correlations of the internal degrees of freedom of entangled atoms. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.2728v2.pdf"}
{"id": "1002.2824", "abstract": "  This is a follow-up of our recently proposed work on pseudopotential calculation (Ref. [21]) of atoms and molecules within DFT framework, using cartesian coordinate grid. Detailed results are presented to demonstrate the usefulness, applicability of the same for a larger set of species (5 atoms; 53 molecules) and exchange-correlation functionals (local, nonlocal). A thorough comparison on total, component, ionization, atomization energies, eigenvalues, potential energy curves with available literature data shows excellent agreement. Additionally, HOMO energies for a series of molecules show significant improvements by using the Leeuwen-Baerends exchange potential, compared to other functionals considered. Comparison with experiments has been made, wherever possible. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.2824v1.pdf"}
{"id": "1002.3327", "abstract": "  We develop a method for calculating the equilibrium properties of the liquid-solid phase transition in a classical, ideal, multi-component plasma. Our method is a semi-analytic calculation that relies on extending the accurate fitting formulae available for the one-, two-, and three-component plasmas to the case of a plasma with an arbitrary number of components. We compare our results to those of Horowitz, Berry,     Brown (Phys. Rev. E, 75, 066101, 2007), who use a molecular dynamics simulation to study the chemical properties of a 17-species mixture relevant to the ocean-crust boundary of an accreting neutron star, at the point where half the mixture has solidified. Given the same initial composition as Horowitz et al., we are able to reproduce to good accuracy both the liquid and solid compositions at the half-freezing point; we find abundances for most species within 10", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.3327v1.pdf"}
{"id": "1002.3536", "abstract": "  We apply the recently developed triangular tessellation technique as presented in [J. de Graaf et al., Phys. Rev. E 80, 051405 (2009)] to calculate the free energy associated with the adsorption of anisotropic colloidal particles at a flat interface. From the free-energy landscape, we analyze the adsorption process, using a simplified version of Langevin dynamics. The present result is a first step to understand the time-dependent behavior of colloids near interfaces. This study shows a wide range of adsorption trajectories, where the emphasis lies on a strong dependence of the dynamics on the orientation of the colloid at initial contact with the interface. We believe that the observed orientational dependence in our simple model can be recovered in suitable experimental systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.3536v1.pdf"}
{"id": "1002.4905", "abstract": "  Nuclear stopping in the heavy ion collisions over a beam energy range from SIS, AGS up to SPS is studied in the framework of the modified UrQMD transport model, in which mean field potentials of both formed and \"pre-formed\" hadrons (from string fragmentation) and medium modified nucleon-nucleon elastic cross sections are considered. It is found that the nuclear stopping is influenced by both the stiffness of the equation of state and the medium modifications of nucleon-nucleon cross sections at SIS energies. At the high SPS energies, the two-bump structure is shown in the experimental rapidity distribution of free protons, which can be understood with the consideration of the \"pre-formed\" hadron potentials. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.4905v1.pdf"}
{"id": "1003.0532", "abstract": "  We investigate the phase separation in one-dimensional Fermi gases on optical lattices. The density distributions and the magnetization are calculated by means of density-matrix renormalization method. The phase separation between spin-up and spin-down atoms is induced by the interplay of the spin-dependent harmonic confinement and the strong repulsive interaction between intercomponent fermions. We find the existence of a critical repulsive interaction strength above which the phase separation evolves. By increasing the trap imbalance, the composite phase of Mott-insulating core is changed into the one of ferromagnetic insulating core, which is incompressible and originates from the Pauli exclusion principle. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.0532v1.pdf"}
{"id": "1003.0608", "abstract": "  We present UBVRI photometry of three symbiotic stars ZZ CMi, TX CVn and AG Peg carried out from 1997 to 2008 in Piwnice Observatory near Torun. To search orbital periods of these stars Fourier analysis was used. For two of them, TX CVn and AG Peg, we have confirmed the earlier known periods. For ZZ CMi we found a relatively short period 218.59 days. Assuming, that the orbital period is twice longer (P=437.18 days), the double sine wave in the light curve can be interpreted by ellipsoidal effect. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.0608v1.pdf"}
{"id": "1003.1041", "abstract": "  In this work we calculate the four-point correlation function of vector quark currents of QCD via holographic QCD model. Computing the correlator we take into account the exchange of vector and axial vector bosons and dilaton in the bulk. The result is used for calculation of the two-point correlator of electromagnetic currents in external magnetic field at zero momentum, related to RHIC experiments, chiral magnetic effect and lattice study. At zero temperature we find this quantity to be loosely connected with chiral symmetry breaking and strongly dependent on the confinement properties. Some features of the AdS/QCD models are also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.1041v2.pdf"}
{"id": "1003.1344", "abstract": "  European options can be priced when returns follow a Student's t-distribution, provided that the asset is capped in value or the distribution is truncated. We call pricing of options using a log Student's t-distribution a Gosset approach, in honour of W.S. Gosset. In this paper, we compare the greeks for Gosset and Black-Scholes formulae and we discuss implementation. The t-distribution requires a shape parameter νto match the \"fat tails\" of the observed returns. For large ν, the Gosset and Black-Scholes formulae are equivalent. The Gosset formulae removes the requirement that the volatility be known, and in this sense can be viewed as an extension of the Black-Scholes formula. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.1344v2.pdf"}
{"id": "1003.1367", "abstract": "  We study by Quantum Monte Carlo simulations the phase diagram of lattice hard core bosons with nearest-neighbour repulsive interactions, in the presence of a super-lattice of adsorption sites. For a moderate adsorption strength, the system forms crystal phases registered with the adsorption lattice; a \"supersolid\" phase exists, on both the vacancy and interstitial sides, whereas at commensuration the superfluid density vanishes. The possible relevance of these results to experiments on ^4He films adsorbed on graphite is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.1367v1.pdf"}
{"id": "1003.1791", "abstract": "  Based on time-dependent Hartree-Fock theory, a new inverse quasifission mechanism is proposed to produce neutron-rich transfermium nuclei, in collision of prolate deformed actinides. Calculations show that collision of the tip of one nucleus with the side of the other results in a nucleon flux toward the latter. The role of nucleon evaporation and impact parameter, as well as the collision time are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.1791v2.pdf"}
{"id": "1003.3475", "abstract": "  We consider the 1.5 years Fermi Large Area Telescope light curves (E > 100 MeV) of the flat spectrum radio quasars 3C 454.3 and PKS 1510-089, which show high activity in this period of time. We characterise the duty cycle of the source by comparing the time spent by the sources at different flux levels. We consider in detail the light curves covering periods of extreme flux. The large number of high-energy photons collected by LAT in these events allows us to find evidence of variability on timescales of few hours. We discuss the implications of significant variability on such short timescales, that challenge the scenario recently advanced in which the bulk of the gamma-ray luminosity is produced in regions of the jet at large distances (tens of parsec) from the black hole. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.3475v2.pdf"}
{"id": "1003.3933", "abstract": "  Two-dimensional electrostatic turbulence in magnetized weakly-collisional plasmas exhibits a cascade of entropy in phase space [Phys. Rev. Lett. 103, 015003 (2009)]. At scales smaller than the gyroradius, this cascade is characterized by the dimensionless ratio D of the collision time to the eddy turnover time measured at the scale of the thermal Larmor radius. When D >> 1, a broad spectrum of fluctuations at sub-Larmor scales is found in both position and velocity space. The distribution function develops structure as a function of v_perp, the velocity coordinate perpendicular to the local magnetic field. The cascade shows a local-scale nonlinear interaction in both position and velocity spaces, and Kolmogorov's scaling theory can be extended into phase space. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.3933v2.pdf"}
{"id": "1003.5792", "abstract": "  We have revisited glueball mixing with the pseudoscalar mesons in the MIT bag model scheme. The calculation has been performed in the spherical cavity approximation to the bag using two different fermion propagators, the cavity and the free propagators. We obtain a very small probability of mixing for the eta at the level of 0.04-0.1", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.5792v1.pdf"}
{"id": "1003.5869", "abstract": "  We consider the wrong-Higgs interactions such as type-III two Higgs doublet models. Generally, such interactions cause flavor problems. However, if new Yukawa interactions have the same flavor structure as that of the standard model(SM), we do not have any flavor problems. In this work we propose a microscopic model for the wrong-Higgs interactions aligned with SM ones in the context of supersymmetry(SUSY) and show their phenomenological implications. Low energy contraints from muon g-2 and rare B decays can be relieved and it can be viable to have low mass superparticle spectra with light dark matter which is preferred by recent experiments such as DAMA/LIBRA, CDMS-II and CoGeNT. We also briefly discuss modification of Higgs decay in colliders. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.5869v1.pdf"}
{"id": "1004.0380", "abstract": "  To understand the correlation and the radiation mechanism of flare emission in different wavelength bands, we have coordinated a number of telescopes to observe SgrA* simultaneously. We focus only on one aspect of the preliminary results of our multi-wavelength observing campaigns, namely, the short time scale variability of emission from SgrA* in near-IR, X-ray and radio wavelengths. The structure function analysis indicate most of the power spectral density is detected on hourly time scales in all wavelength bands. We also report minute time scale variability at 7 and 13mm placing a strong constraint on the nature of the variable emission. The hourly time scale variability can be explained in the context of a model in which the peak frequency of emission shifts toward lower frequencies as a self-absorbed synchrotron source expands adiabatically near the acceleration site. The short time scale variability, on the other hand, places a strong constraint on the size of the emitting region. Assuming that rapid minute time scale fluctuations of the emission is optically thick in radio wavelength, light travel arguments requires relativistic particle energy, thus suggesting the presence of outflow from SgrA*. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.0380v1.pdf"}
{"id": "1004.0695", "abstract": "  We update cosmological hot dark matter constraints on neutrinos and hadronic axions. Our most restrictive limits use 7-year data from the Wilkinson Microwave Anisotropy Probe for the cosmic microwave background anisotropies, the halo power spectrum (HPS) from the 7th data release of the Sloan Digital Sky Survey, and the Hubble constant from Hubble Space Telescope observations. We find 95", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.0695v2.pdf"}
{"id": "1004.1173", "abstract": "  We use Shen et al.'s (2009) measurements of luminosity-dependent clustering in the SDSS Data Release 5 Quasar Catalog, at redshifts 0.4 < z < 2.5, to constrain the relation between quasar luminosity and host halo mass and to infer the duty cycle f_opt, the fraction of black holes that shine as optically luminous quasars at a given time. We assume a monotonic mean relation between quasar luminosity and host halo mass, with log-normal scatter Σ. For specified f_opt and Σ, matching the observed quasar space density determines the normalization of the luminosity-halo mass relation, from which we predict the clustering bias. The data show no change of bias between the faint and bright halves of the quasar sample but a modest increase in bias for the brightest 10", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.1173v1.pdf"}
{"id": "1004.3231", "abstract": "  A constraint on the viable f(R) model is investigated by confronting theoretical predictions with the multipole power spectrum of the luminous red galaxy sample of the Sloan Digital Sky survey data release 7. We obtain a constraint on the Compton wavelength parameter of the f(R) model on the scales of cosmological large-scale structure. A prospect of constraining the Compton wavelength parameter with a future redshift survey is also investigated. The usefulness of the redshift-space distortion for testing the gravity theory on cosmological scales is demonstrated. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.3231v1.pdf"}
{"id": "1004.3700", "abstract": "  Shortcomings of experimental techniques are usually assumed to diminish nonclassical properties of quantum systems. Here it is demonstrated that this standard assumption is not true in general. It is theoretically shown that the inability to resolve different photon numbers in photodetection may pseudo-increase a measured Bell parameter. Under proper conditions one even pseudo-violates the quantum Cirel'son bound of the Bell parameter, the corresponding density operator fails to be positive semi-definite. This paradox can be resolved by appropriate squash models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.3700v3.pdf"}
{"id": "1004.3937", "abstract": "  Static observers in curved spacetimes may interpret their proper acceleration as the opposite of a local gravitational field (in the Newtonian sense). Based on this interpretation and motivated by the equivalence principle, we are led to investigate congruences of timelike curves in Minkowski spacetime whose acceleration field coincides with the acceleration field of static observers of curved spaces. The congruences give rise to non-inertial frames that are examined. Specifically we find, based on the locality principle, the embedding of simultaneity hypersurfaces adapted to the non-inertial frame in an explicit form for arbitrary acceleration fields. We also determine, from the Einstein equations, a covariant field equation that regulates the behavior of the proper acceleration of static observers in curved spacetimes. It corresponds to an exact relativistic version of the Newtonian gravitational field equation. In the specific case in which the level surfaces of the norm of the acceleration field of the static observers are maximally symmetric two-dimensional spaces, the energy-momentum tensor of the source is analyzed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.3937v1.pdf"}
{"id": "1004.4434", "abstract": "  The thermodynamical properties of heterogeneous DNA sequences are computed by path integral techniques applied to a nonlinear model Hamiltonian. The base pairs relative displacements are interpreted as time dependent paths whose amplitudes are consistent with the model potential for the hydrogen bonds between complementary strands. The portion of configuration space contributing to the partition function is determined, at any temperature, by selecting the ensemble of paths which fulfill the second law of thermodynamics. For a short DNA fragment, the denaturation is signaled by a succession of peaks in the specific heat plots while the entropy grows continuously versus T. Thus, the opening of the double strand with bubble formation appears as a smooth crossover due to base pair fluctuation effects which are accounted for by the path integral method. The multistep transition is driven by the AT-rich regions of the DNA fragment. The base pairs path ensemble shows an enhanced degree of cooperativity at about the same temperatures for which the specific heat peaks occur. These findings establish a link between microscopic and macroscopic signatures of the transition. The fractions of mean base pair stretchings are computed by varying the AT base pairs content and taking some threshold values for the occurrence of the molecule denaturation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.4434v1.pdf"}
{"id": "1004.5279", "abstract": "  The concept of ratchets, driven asymmetric periodic structures giving rise to directed particle flow, has recently been generalized to a quantum ratchet mechanism for spin currents mediated through spin-orbit interaction. Here we consider such systems in the coherent mesoscopic regime and generalize the proposal of a minimal spin ratchet model based on a non-interacting clean quantum wire with two transverse channels by including disorder and by self-consistently treating the charge redistribution in the nonlinear (adiabatic) ac-driving regime. Our Keldysh-Green function based quantum transport simulations show that the spin ratchet mechanism is robust and prevails for disordered, though non-diffusive, mesoscopic structures. Extending the two-channel to the multi-channel case does not increase the net ratchet spin current efficiency but, remarkably, yields a dc spin transmission increasing linearly with channel number. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.5279v1.pdf"}
{"id": "1005.0175", "abstract": "  Rounding border effects at the escape point of open integrable billiards are analyzed via the escape times statistics and emission angles. The model is the rectangular billiard and the shape of the escape point is assumed to have a semicircular form. Stickiness and self-similar structures for the escape times and emission angles are generated inside \"backgammon\" like stripes of initial conditions. These stripes are born at the boundary between two different emission angles but same escape times. As the rounding effects increase, backgammon stripes start to overlap and the escape times statistics obeys the power law decay and anomalous diffusion is expected. Tiny rounded borders (around 0.1% from the whole billiard size) are shown to be sufficient to generate the sticky motion, while borders larger than 10% are enough to produce escape times with chaotic decay. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1005/1005.0175v1.pdf"}
{"id": "1005.0370", "abstract": "  We study the tunneling conductance of a clean normal metal/chiral p-wave superconductor junction using the extended Blonder-Tinkham-Klapwijk formalism. It is shown that the spin-orbit coupling of the Rashba type that is present near the interface causes the subgap conductance peaks associated with the Andreev surface bound states to shift to a nonzero bias. We also investigate the effect of the Fermi wavevector mismatch between the normal metal and the superconductor. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1005/1005.0370v1.pdf"}
{"id": "1005.2200", "abstract": "  The concept of a protein diffusing in its free energy folding landscape has been fruitful for both theory and experiment. Yet the choice of the reaction coordinate (RC) introduces an undesirable degree of arbitrariness into the problem. We analyze extensive simulation data of an alpha-helix in explicit water solvent as it stochastically folds and unfolds. The free energy profiles for different RCs exhibit significant variation, some having an activation barrier, others not. We show that this variation has little effect on the predicted folding kinetics if the diffusivity profiles are properly taken into account. This kinetic quasi-universality is rationalized by an RC rescaling, which, due to the reparameterization invariance of the Fokker-Planck equation, allows the combination of free energy and diffusivity effects into a single function, the rescaled free energy profile. This rescaled free energy indeed shows less variation among different RCs than the bare free energy and diffusivity profiles separately do, if we properly distinguish between RCs that contain knowledge of the native state and those that are purely geometric in nature. Our method for extracting diffusivity profiles is easily applied to experimental single molecule time series data and might help to reconcile conflicts that arise when comparing results from different experimental probes for the same protein. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1005/1005.2200v1.pdf"}
{"id": "1005.3667", "abstract": "  Observations of the polar region of the Sun are critically important for understanding the solar dynamo and the acceleration of solar wind. We carried out precise magnetic observations on both the North polar region and the quiet Sun at the East limb with the Spectro-Polarimeter of the Solar Optical Telescope aboard Hinode to characterize the polar region with respect to the quiet Sun. The average area and the total magnetic flux of the kG magnetic concentrations in the polar region appear to be larger than those of the quiet Sun. The magnetic field vectors classified as vertical in the quiet Sun have symmetric histograms around zero in the strengths, showing balanced positive and negative flux, while the histogram in the North polar region is clearly asymmetric, showing a predominance of the negative polarity. The total magnetic flux of the polar region is larger than that of the quiet Sun. In contrast, the histogram of the horizontal magnetic fields is exactly the same between the polar region and the quiet Sun. This is consistent with the idea that a local dynamo process is responsible for the horizontal magnetic fields. A high-resolution potential field extrapolation shows that the majority of magnetic field lines from the kG-patches in the polar region are open with a fanning-out structure very low in the atmosphere, while in the quiet Sun, almost all the field lines are closed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1005/1005.3667v1.pdf"}
{"id": "1006.2869", "abstract": "  Using the Wang-Landau flat histogram Monte Carlo (FHMC) simulation technique, we were able to study two types of triangulated spherical surface models in which the two-dimensional extrinsic curvature energy is assumed in the Hamiltonian. The Gaussian bond potential is also included in the Hamiltonian of the first model, but it is replaced by a hard-wall potential in the second model. The results presented in this paper are in good agreement with the results previously reported by our group. The transition of surface fluctuations and collapsing transition were studied using the canonical Metropolis Monte Carlo simulation technique and were found to be of the first-order. The results obtained in this paper also show that the FHMC technique can be successfully applied to triangulated surface models. It is non-trivial whether the technique is applicable or not to surface models because the simulations are performed on relatively large surfaces. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1006/1006.2869v1.pdf"}
{"id": "1006.3957", "abstract": "  The shock response of two-dimensional model high explosive crystals with various arrangements of circular voids is explored. We simulate a piston impact using molecular dynamics simulations with a Reactive Empirical Bond Order (REBO) model potential for a sub-micron, sub-ns exothermic reaction in a diatomic molecular solid. In square lattices of voids (of equal size), reducing the size of the voids or increasing the porosity while holding the other parameter fixed causes the hotspots to consume the material more quickly and detonation to occur sooner and at lower piston velocities. The early time behavior is seen to follow a very simple ignition and growth model. The hotspots are seen to collectively develop a broad pressure wave (a sonic, diffuse deflagration front) that, upon merging with the lead shock, transforms it into a detonation. The reaction yields produced by triangular lattices are not significantly different. With random void arrangements, the mean time to detonation is 15.5% larger than with the square lattice; the standard deviation of detonation delays is just 5.1", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1006/1006.3957v1.pdf"}
{"id": "1006.4675", "abstract": "  It is an open, but not unanswerable, question as to how much atmospheric CO2 is sequestered globally by vegetation fires. In this work I conceptualise the question in terms of the general CharXive Challenge, discuss a mechanism by which thermoconversion of biomass may regulate the global distribution of carbon between reservoirs, show how suppression of vegetation fires by human activities may increase the fraction of carbon in the atmospheric pool, and pose three specific CharXive Challenges of crucial strategic significance to our management of global carbon cycles. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1006/1006.4675v1.pdf"}
{"id": "1007.0098", "abstract": "  An exactly solvable variant of mixed spin-(1/2,1) Ising-Heisenberg diamond chain is considered. Vertical spin-1 dimers are taken as quantum ones with Heisenberg bilinear and biquadratic interactions and with single-ion anisotropy, while all interactions between spin-1 and spin-1/2 residing on the intermediate sites are taken in the Ising form. The detailed analysis of the T=0 ground state phase diagram is presented. The phase diagrams have shown to be rather rich, demonstrating large variety of ground states: saturated one, three ferrimagnetic with magnetization equal to 3/5 and another four ferrimagnetic ground states with magnetization equal to 1/5. There are also two frustrated macroscopically degenerated ground states which could exist at zero magnetic filed.   Solving the model exactly within classical transfer-matrix formalism we obtain an exact expressions for all thermodynamic function of the system. The thermodynamic properties of the model have been described exactly by exact calculation of partition function within the direct classical transfer-matrix formalism, the entries of transfer matrix, in their turn, contain the information about quantum states of vertical spin-1 XXZ dimer (eigenvalues of local hamiltonian for vertical link). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1007/1007.0098v2.pdf"}
{"id": "1007.0517", "abstract": "  When Einstein formulated his special relativity in 1905, he established the law of Lorentz transformations for point particles. It is now known that particles have internal space-time structures. Particles, such as photons and electrons, have spin variables. Protons and other hadrons are regarded as bound states of more fundamental particles called quarks which have their internal variables. It is still one of the most outstanding problems whether these internal space-time variables are transformed according to Einstein's law of Lorentz transformations. It is noted that Wigner, Dirac, and Feynman made important contributions to this problem. By integrating their efforts, it is then shown possible to construct a picture of the internal space-time symmetry consistent with Einstein's Lorentz covariance. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1007/1007.0517v1.pdf"}
{"id": "1007.0521", "abstract": "  We introduce a new Forward-Flux Sampling in Time (FFST) algorithm to efficiently measure transition times in rare-event processes in non-equilibrium systems, and apply it to study the first-order (discontinuous) kinetic transition in the Ziff-Gulari-Barshad model of catalytic surface reaction. The average time for the transition to take place, as well as both the spinodal and transition points, are clearly found by this method. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1007/1007.0521v1.pdf"}
{"id": "1007.1527", "abstract": "  A five-dimensional seesaw framework is analyzed with the lepton-number-violating propagator of bulk right-handed neutrinos. That can bypass summing up the effects of heavy Majorana particles whose masses and wavefunctions are not exactly known. The propagator method makes it easier to evaluate the seesaw-induced neutrino mass for various boundary conditions of bulk neutrinos and in a general background geometry, including the warped extra dimension. It is also found that the higher-dimensional seesaw gives a natural framework for the inverse seesaw suppression of low-energy neutrino masses. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1007/1007.1527v1.pdf"}
{"id": "1007.2486", "abstract": "  The transmission of evanescent waves in a gain-compensated perfect lens is discussed. In particular, the impact of gain saturation is included in the analysis, and a method for calculating the fields of such nonlinear systems is developed. Gain compensation clearly improves the resolution; however, a number of nonideal effects arise as a result of gain saturation. The resolution associated with the lens is strongly dependent on the saturation constant of the active medium. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1007/1007.2486v1.pdf"}
{"id": "1007.3685", "abstract": "  As a result of a new improved fit to old bubble chamber data of the dominant axial C_5^A nucleon-to-Delta form factor, and due to the relevance of this form factor for neutrino induced coherent pion production, we re-evaluate our model predictions in Phys. Rev. D79, 013002 (2009) for different observables of the latter reaction. Central values for the total cross sections increase by 20", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1007/1007.3685v2.pdf"}
{"id": "1007.4113", "abstract": "  Strategy changes are an essential part of evolutionary games. Here we introduce a simple rule that, depending on the value of a single parameter w, influences the selection of players that are considered as potential sources of the new strategy. For positive w players with high payoffs will be considered more likely, while for negative w the opposite holds. Setting w equal to zero returns the frequently adopted random selection of the opponent. We find that increasing the probability of adopting the strategy from the fittest player within reach, i.e. setting w positive, promotes the evolution of cooperation. The robustness of this observation is tested against different levels of uncertainty in the strategy adoption process and for different interaction network. Since the evolution to widespread defection is tightly associated with cooperators having a lower fitness than defectors, the fact that positive values of w facilitate cooperation is quite surprising. We show that the results can be explained by means of a negative feedback effect that increases the vulnerability of defectors although initially increasing their survivability. Moreover, we demonstrate that the introduction of w effectively alters the interaction network and thus also the impact of uncertainty by strategy adoptions on the evolution of cooperation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1007/1007.4113v1.pdf"}
{"id": "1008.2130", "abstract": "  Binary radio pulsars are generally believed to have been spun up to millisecond periods (i.e. recycling) via mass accretion from their donor stars, and they are the descendants of neutron star low-mass X-ray binaries. However, some studies indicate that the formation of pulsars from the accretion-induced collapse (AIC) of accreting white dwarfs (WDs) cannot be excluded. In this work, we use a population synthesis code to examine if the AIC channel can produce eccentric binary millisecond pulsars (BMSPs) in the Galaxy. Our simulated results indicate that, only when the natal MSPs receive a relatively strong kick (100 km s^-1), can the AIC channel produce ∼ 10-180 eccentric (e>0.1) BMSPs in the Galaxy, most of which are accompanied by a Helium star. Such a kick seems to be highly unlikely in the conventional AIC process, hence the probability of forming eccentric BMSPs via the AIC channel can be ruled out. Even if a high kick is allowed, the AIC channel cannot produce eccentric BMSPs with an orbital period of 20 days. Therefore, we propose that the peculiar BMSP PSR J1903+0327 cannot be formed by the AIC channel. However, the AIC evolutionary channel may produce some fraction of isolated millisecond pulsars, and even sub-millisecond pulsars if they really exist. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1008/1008.2130v2.pdf"}
{"id": "1008.3406", "abstract": "  We determine the zero temperature quantum phase diagram of a p_x+ip_y pairing model based on the exactly solvable hyperbolic Richardson-Gaudin model. We present analytical and large-scale numerical results for this model. In the continuum limit, the exact solution exhibits a third-order quantum phase transition, separating a strong-pairing from a weak-pairing phase. The mean field solution allows to connect these results to other models with p_x+ip_y pairing order. We define an experimentally accessible characteristic length scale, associated with the size of the Cooper pairs, that diverges at the transition point, indicating that the phase transition is of a confinement-deconfinement type without local order parameter. We show that this phase transition is not limited to the p_x+ip_y pairing model, but can be found in any representation of the hyperbolic Richardson-Gaudin model and is related to a symmetry that is absent in the rational Richardson-Gaudin model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1008/1008.3406v3.pdf"}
{"id": "1008.3937", "abstract": "  In a recent contribution [Phys. Rev. B 81, 165104 (2010)] fermionic Projected Entangled-Pair States (PEPS) were used to approximate the ground state of free and interacting spinless fermion models, as well as the t-J model. This paper revisits these three models in the presence of an additional next-nearest hopping amplitude in the Hamiltonian. First we explain how to account for next-nearest neighbor Hamiltonian terms in the context of fermionic PEPS algorithms based on simulating time evolution. Then we present benchmark calculations for the three models of fermions, and compare our results against analytical, mean-field, and variational Monte Carlo results, respectively. Consistent with previous computations restricted to nearest-neighbor Hamiltonians, we systematically obtain more accurate (or better converged) results for gapped phases than for gapless ones. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1008/1008.3937v2.pdf"}
{"id": "1008.4368", "abstract": "  I provide a pedagogic review of adaptive mesh refinement (AMR) radiation hydrodynamics (RHD) methods and codes used in simulations of star formation, at a level suitable for researchers who are not computational experts. I begin with a brief overview of the types of RHD processes that are most important to star formation, and then I formally introduce the equations of RHD and the approximations one uses to render them computationally tractable. I discuss strategies for solving these approximate equations on adaptive grids, with particular emphasis on identifying the main advantages and disadvantages of various approximations and numerical approaches. Finally, I conclude by discussing areas ripe for improvement. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1008/1008.4368v1.pdf"}
{"id": "1009.2323", "abstract": "  Lithium abundances are presented and discussed for 70 members of the 50 Myr old open cluster alpha Per. More than half of the abundances are from new high-resolution spectra. The Li abundance in the F-type stars is equal to its presumed initial abundance confirming previous suggestions that pre-main sequence depletion is ineffective for these stars. Intrinsic star-to-star scatter in Li abundance among these stars is comparable to the measurement uncertainties. There is marginal evidence that the stars of high projected rotational velocity v sini follow a different abundance vs temperature trend to the slow rotators. For stars cooler than about 5500 K, the Li abundance declines steeply with decreasing temperature and there develops a star-to-star scatter in the Li abundance. This scatter is shown to resemble the well documented scatter seen in the 70 Myr old Pleiades cluster. The scatter appears to be far less pronounced in the 30 Myr clusters which have been studied for Li abundance. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.2323v1.pdf"}
{"id": "1009.3041", "abstract": "  The problem of secret sharing over the Gaussian wiretap channel is considered. A source and a destination intend to share secret information over a Gaussian channel in the presence of a wiretapper who observes the transmission through another Gaussian channel. Two constraints are imposed on the source-to-destination channel; namely, the source can transmit only binary phase shift keyed (BPSK) symbols, and symbol-by-symbol hard-decision quantization is applied to the received symbols of the destination. An error-free public channel is also available for the source and destination to exchange messages in order to help the secret sharing process. The wiretapper can perfectly observe all messages in the public channel. It is shown that a secret sharing scheme that employs a random ensemble of regular low density parity check (LDPC) codes can achieve the key capacity of the BPSK-constrained Gaussian wiretap channel asymptotically with increasing block length. To accommodate practical constraints of finite block length and limited decoding complexity, fixed irregular LDPC codes are also designed to replace the regular LDPC code ensemble in the proposed secret sharing scheme. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.3041v3.pdf"}
{"id": "1009.4562", "abstract": "  We perform time-dependent simulations of spin exchange for an electron pair in laterally coupled quantum dots. The calculation is based on configuration interaction scheme accounting for spin-orbit (SO) coupling and electron-electron interaction in a numerically exact way. Noninteracting electrons exchange orientations of their spins in a manner that can be understood by interdot tunneling associated with spin precession in an effective SO magnetic field that results in anisotropy of the spin swap. The Coulomb interaction blocks the electron transfer between the dots but the spin transfer and spin precession due to SO coupling is still observed. The electron-electron interaction additionally induces an appearance of spin components in the direction of the effective SO magnetic field which are opposite in both dots. Simulations indicate that the isotropy of the spin swap is restored for equal Dresselhaus and Rashba constants and properly oriented dots. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.4562v1.pdf"}
{"id": "1009.5198", "abstract": "  The effect of intrinsic channel noise is investigated for the dynamic response of a neuronal cell with a delayed feedback loop. The loop is based on the so-called autapse phenomenon in which dendrites establish not only connections to neighboring cells but as well to its own axon. The biophysical modeling is achieved in terms of a stochastic Hodgkin-Huxley model containing such a built in delayed feedback. The fluctuations stem from intrinsic channel noise, being caused by the stochastic nature of the gating dynamics of ion channels. The influence of the delayed stimulus is systematically analyzed with respect to the coupling parameter and the delay time in terms of the interspike interval histograms and the average interspike interval. The delayed feedback manifests itself in the occurrence of bursting and a rich multimodal interspike interval distribution, exhibiting a delay-induced reduction of the spontaneous spiking activity at characteristic frequencies. Moreover, a specific frequency-locking mechanism is detected for the mean interspike interval. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.5198v3.pdf"}
{"id": "1010.0034", "abstract": "  The eigenvalue spectrum of the adjacency matrix of a network is closely related to the behavior of many dynamical processes run over the network. In the field of robotics, this spectrum has important implications in many problems that require some form of distributed coordination within a team of robots. In this paper, we propose a continuous-time control scheme that modifies the structure of a position-dependent network of mobile robots so that it achieves a desired set of adjacency eigenvalues. For this, we employ a novel abstraction of the eigenvalue spectrum by means of the adjacency matrix spectral moments. Since the eigenvalue spectrum is uniquely determined by its spectral moments, this abstraction provides a way to indirectly control the eigenvalues of the network. Our construction is based on artificial potentials that capture the distance of the network's spectral moments to their desired values. Minimization of these potentials is via a gradient descent closed-loop system that, under certain convexity assumptions, ensures convergence of the network topology to one with the desired set of moments and, therefore, eigenvalues. We illustrate our approach in nontrivial computer simulations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.0034v1.pdf"}
{"id": "1010.1351", "abstract": "  Over the past few decades, superhydrophobic materials have attaracted a lot of interests, due to their numerous practical applications. Among various superhydrophobic materials, carbon nanotube arrays have gained enormous attentions simply because of their outstanding properties. The impact dynamic of water droplet on a superhydrophobic carbon nanotube array is shown in this fluid dynamics video. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.1351v1.pdf"}
{"id": "1010.3115", "abstract": "  Anomalous diffusion is predicted for Brownian particles in inhomogeneous viscosity landscapes by means of scaling arguments, which are substantiated through numerical simulations. Analytical solutions of the related Fokker-Planck equation in limiting cases confirm our results. For an ensemble of particles starting at a spatial minimum (maximum) of the viscous damping we find subdiffusive (superdiffusive) motion. Superdiffusion occurs also for a monotonically varying viscosity profile. We suggest different substances for related experimental investigations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.3115v1.pdf"}
{"id": "1010.4636", "abstract": "  We have studied the Hall effect in superconducting tantalum nitride films. We find a large contribution to the Hall conductivity near the superconducting transition, which we can track to temperatures well above T_c and magnetic fields well above the upper critical field, H_c2(0). This contribution arises from Aslamazov-Larkin superconducting fluctuations, and we find quantitative agreement between our data and recent theoretical analysis based on time dependent Ginzburg-Landau theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.4636v2.pdf"}
{"id": "1010.5107", "abstract": "  The effect of a classical gravitational field on the spin entanglement of a system of two spin-1/2 particles moving in the curved spacetime is discussed. The system is described by a two-particle Gaussian wave packet represented in the momentum space and both the acceleration of the system and the curvature of the spacetime cause to produce a Wigner rotation acting on the wave packet as it moves along a path in the curved spacetime. By calculating the reduced density operator at a final point, we focus on the spin entanglement of the system. In a spherically symmetric and static gravitational field, for example a charged black hole, there can be particular paths on which the Wigner rotation is trivial and so the initial reduced density matrix remains intact. This causes the spin entanglement to be invariant during the motion. The spin entanglement descends to zero by increasing the angular velocity of the mean centroid of the system as well increasing the proper time during which the centroid moves on its circular path around the center. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.5107v1.pdf"}
{"id": "1010.5499", "abstract": "  We present new insights about accretion and ejection physics based on joint RXTE/Chandra HETGS studies of rapid X-ray variability in GRS 1915+105. For the first time, with fast phase-resolved spectroscopy of the rho state, we are able to show that changes in the broadband X-ray spectrum (RXTE) on timescales of seconds are associated with measurable changes in absorption lines (Chandra HETGS) from the accretion disk wind. Additionally, we make a direct detection of material evaporating from the radiation-pressure-dominated inner disk. Our X-ray data thus reveal the black hole as it ejects a portion of the inner accretion flow and then drives a wind from the outer disk, all in a bizarre cycle that lasts fewer than 60 seconds but can repeat for weeks. We find that the accretion disk wind may be sufficiently massive to play an active role in GRS 1915+105, not only in quenching the jet on long timescales, but also in possibly producing or facilitating transitions between classes of X-ray variability. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.5499v1.pdf"}
{"id": "1010.5901", "abstract": "  Using computer simulations we investigate the homogeneous crystal nucleation in suspensions of colloidal hard dumbbells. The free energy barriers are determined by Monte Carlo simulations using the umbrella sampling technique. We calculate the nucleation rates for the plastic crystal and the aperiodic crystal phase using the kinetic prefactor as determined from event driven molecular dynamics simulations. We find good agreement with the nucleation rates determined from spontaneous nucleation events observed in event driven molecular dynamics simulations within error bars of one order of magnitude. We study the effect of aspect ratio of the dumbbells on the nucleation of plastic and aperiodic crystal phases and we also determine the structure of the critical nuclei. Moreover, we find that the nucleation of the aligned CP1 crystal phase is strongly suppressed by a high free energy barrier at low supersaturations and slow dynamics at high supersaturations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.5901v2.pdf"}
{"id": "1011.0736", "abstract": "  Spin chains have been proposed as quantum wires in many quantum information processing architectures. Coherent transmission of quantum information over short distances is enabled by their internal dynamics, which drives the transport of single-spin excitations in perfectly polarized chains. Given the practical challenge of preparing the chain in a pure state, we propose to use a chain that is initially in the maximally mixed state. We compare the transport properties of pure and mixed-state chains, finding similarities that enable the experimental study of pure-state transfer by its simulation via mixed-state chains, and demonstrate protocols for the perfect transfer of quantum information in these chains. Remarkably, mixed-state chains allow the use of Hamiltonians which do not preserve the total number of excitations, and which are more readily obtainable from the naturally occurring magnetic dipolar interaction. We propose experimental implementations using solid-state nuclear magnetic resonance and defect centers in diamond. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1011/1011.0736v1.pdf"}
{"id": "1011.2099", "abstract": "  Previous surveys of outflows in low-redshift active galactic nuclei (AGN) have relied on the analysis of sources selected primarily for their optical/X-ray brightness, and are therefore biased. Towards determining the outflow properties of local AGN, we detect warm absorption signatures of O VII and O VIII absorption edges in the available Suzaku/XMM-Newton CCD spectra of an unbiased sample of 44 Seyfert 1-1.5 sources selected in the very hard X-rays (14-195 keV) with the Swift Burst Alert Telescope. From our analysis, we find that O VII and O VIII absorption edges are present in 41", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1011/1011.2099v1.pdf"}
{"id": "1011.4059", "abstract": "  Large, multi-frequency imaging surveys, such as the Large Synaptic Survey Telescope (LSST), need to do near-real time analysis of very large datasets. This raises a host of statistical and computational problems where standard methods do not work. In this paper, we study a proposed method for combining stacks of images into a single summary image, sometimes referred to as a template. This task is commonly referred to as image coaddition. In part, we focus on a method proposed in previous work, which outlines a procedure for combining stacks of images in an online fashion in the Fourier domain. We evaluate this method by comparing it to two straightforward methods through the use of various criteria and simulations. Note that the goal is not to propose these comparison methods for use in their own right, but to ensure that additional complexity also provides substantially improved performance. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1011/1011.4059v1.pdf"}
{"id": "1011.4877", "abstract": "  The mass spectrum of the noncommutative QED in two-dimensional Euclidean ℝ^2 space is derived first in a perturbative approach at one-loop level and then in a nonperturbative approach using the equivalent bosonized noncommutative effective action. It turns out that the mass spectrum of noncommutative QED in two dimensions reduces to a single non-interacting meson with mass M_γ=g/√(π), as in commutative Schwinger model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1011/1011.4877v3.pdf"}
{"id": "1012.0607", "abstract": "  The properties of the two-dimensional exactly solvable Lieb and Baxter models in the critical region are considered based on the thermodynamic method of investigation of a one-component system critical state. From the point of view of the thermodynamic stability the behaviour of adiabatic and isodynamic parameters for these models is analyzed and the types of their critical behaviour are determined. The reasons for the violation of the scaling law hypothesis and the universality hypothesis for the models are clarified. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.0607v1.pdf"}
{"id": "1012.1159", "abstract": "  An enhanced model, based on the Extended Boson Approximation, for the lowest-lying states in odd-mass nuclei is presented. Our approach is built on the Quasiparticle Phonon Model, extending it to take into account the ground state correlations due to the action of the Pauli principle more accurately than in the conventional theory. The derived interaction strengths between the quasiparticles and the phonons in this model depend on the quasiparticle occupation numbers explicitly coupling the odd-mass nucleus equations with those of the even-even core. Within this model we calculated the transition probabilities in several Te, Xe and Ba isotopes with A≈130. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.1159v1.pdf"}
{"id": "1012.1376", "abstract": "  We examine the recoil velocity induced by the superposition of the magnetic dipole and quadrupole radiation from a pulsar/magnetar born with rapid rotation. The resultant velocity depends on not the magnitude, but rather the ratio of the two moments and their geometrical configuration. The model does not necessarily lead to high spatial velocity for a magnetar with a strong magnetic field, which is consistent with the recent observational upper bound. The maximum velocity predicted with this model is slightly smaller than that of observed fast-moving pulsars. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.1376v1.pdf"}
{"id": "1012.4384", "abstract": "  In recent years there has been a considerable increase in the publishing of textbooks and monographs covering what was formerly known as random or irregular deterministic motion, now named by the more fashionable term of deterministic chaos. There is still substantial interest in a matter that is included in many graduate and even undergraduate courses on classical mechanics. Based on the Hamiltonian formalism, the main objective of this article is to provide, from the physicist's point of view, an overall and intuitive review of this broad subject (with some emphasis on the KAM theorem and the stability of planetary motions) which may be useful to both students and instructors. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.4384v1.pdf"}
{"id": "1012.5301", "abstract": "  We report monitoring observations of the T Tauri star EX Lupi during its outburst in 2008 in the CO fundamental band at 4.6-5.0 um. The observations were carried out at the VLT and the Subaru Telescope at six epochs from April to August 2008, covering the plateau of the outburst and the fading phase to a quiescent state. The line flux of CO emission declines with the visual brightness of the star and the continuum flux at 5 um, but composed of two subcomponents that decay with different rates. The narrow line emission (50 km s-1 in FWHM) is near the systemic velocity of EX Lupi. These emission lines appear exclusively in v=1-0. The line widths translate to a characteristic orbiting radius of 0.4 AU. The broad line component (FWZI   150 km s-1) is highly excited upto v<=6. The line flux of the component decreases faster than the narrow line emission. Simple modeling of the line profiles implies that the broad-line emitting gas is orbiting around the star at 0.04-0.4 AU. The excitation state, the decay speed of the line flux, and the line profile, indicate that the broad-line emission component is physically distinct from the narrow-line emission component, and more tightly related to the outburst event. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.5301v1.pdf"}
{"id": "1012.5549", "abstract": "  Chaotic micromixers such as the staggered herringbone mixer developed by Stroock et al. allow efficient mixing of fluids even at low Reynolds number by repeated stretching and folding of the fluid interfaces. The ability of the fluid to mix well depends on the rate at which \"chaotic advection\" occurs in the mixer. An optimization of mixer geometries is a non trivial task which is often performed by time consuming and expensive trial and error experiments. In this paper an algorithm is presented that applies the concept of finite-time Lyapunov exponents to obtain a quantitative measure of the chaotic advection of the flow and hence the performance of micromixers. By performing lattice Boltzmann simulations of the flow inside a mixer geometry, introducing massless and non-interacting tracer particles and following their trajectories the finite time Lyapunov exponents can be calculated. The applicability of the method is demonstrated by a comparison of the improved geometrical structure of the staggered herringbone mixer with available literature data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.5549v4.pdf"}
{"id": "1101.2388", "abstract": "  A simulation scheme of quantum version of Cournot's Duopoly is proposed, in which there is a new Nash equilibrium that may be also Pareto optimal without any entanglement involved. The unique property of this simulation scheme is decoherence-free against the symmetric photon loss. Furthermore, we analyze the effects of the asymmetric information on this simulation scheme and investigate the case of asymmetric game caused by asymmetric photon loss. A second-order phase transition-like behavior of the average profits of the firm 1 and firm 2 in Nash equilibrium can be observed with the change of the degree of asymmetry of the information or the degree of \"virtual cooperation\". It is also found that asymmetric photon loss in this simulation scheme plays a similar role with the asymmetric entangled states in the quantum game.   PACS numbers: 02.50.Le, 03.67.-a ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1101/1101.2388v2.pdf"}
{"id": "1101.4602", "abstract": "  We study the accretion of modified Chaplygin gas upon different types of black hole. Modified Chaplygin gas is one of the best candidates for a combined model of dark matter and dark energy. In addition, from a field theoretical point of view the modified Chaplygin gas model is equivalent to that of a scalar field having a self-interacting potential. We formulate the equations related to both spherical accretion and disc accretion, and respective winds. The corresponding numerical solutions of the flow, particularly of velocity, are presented and are analyzed. We show that the accretion-wind system of modified Chaplygin gas dramatically alters the wind solutions, producing faster winds, upon changes in physical parameters, while accretion solutions qualitatively remain unaffected. This implies that modified Chaplygin gas is more prone to produce outflow which is the natural consequence of the dark energy into the system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1101/1101.4602v1.pdf"}
{"id": "1102.2144", "abstract": "  The steady state motion of cylindrical droplets under the action of external body force is investigated both theoretically and via lattice Boltzmann simulation. As long as the shape-invariance of droplet is maintained, the droplet's center-of-mass velocity linearly scales with both the force density and the square of droplet radius. However, a non-linear behavior appears as the droplet deformation becomes significant. This deformation is associated with the drop elongation occurring at sufficiently high external forcing. Yet, independent of either the force density or the droplet size, the center-of-mass velocity is found to be linear in terms of the inverse of dynamic viscosity. In addition, it is shown that the energy is mainly dissipated in a region near the substrate particularly close to the three phase contact line. The total viscous dissipation is found to be proportional to both the square of force density and the inverse of dynamic viscosity. Moreover, the dependence of the center-of-mass velocity on the equilibrium contact angle is investigated. A simple analytic model is provided reproducing the observed behavior. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.2144v1.pdf"}
{"id": "1102.3017", "abstract": "  We show that backflow correlations in the variational wave function for the Hubbard model greatly improve the previous results given by the Slater-Jastrow state, usually considered in this context. We provide evidence that, within this approach, it is possible to have a satisfactory connection with the strong-coupling regime. Moreover, we show that, for the Hubbard model on the lattice, backflow correlations are essentially short range, inducing an effective attraction between empty (holons) and doubly occupied sites (doublons). In presence of frustration, we report the evidence that the metal to Mott-insulator transition is marked by a discontinuity of the double occupancy, together with a similar discontinuity of the kinetic term that does not change the number of holons and doublons, while the other kinetic terms are continuous across the transition. Finally, we show the estimation of the charge gap, obtained by particle-hole excitations à la Feynman over the ground-state wave function. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.3017v1.pdf"}
{"id": "1102.4659", "abstract": "  Identifying non-Markovianity with non-divisibility, we propose a measure for non-Markovinity of quantum process. Three examples are presented to illustrate the non-Markovianity, measure for non-Markovianity is calculated and discussed. Comparison with other measures of non-Markovianity is made. Our non-Markovianity measure has the merit that no optimization procedure is required and it is finite for any quantum process, which greatly enhances the practical relevance of the proposed measure. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.4659v1.pdf"}
{"id": "1103.3184", "abstract": "  A simple stochastic model which describes microtubule dynamics and explicitly takes into account the relevant biochemical processes is presented. The model incorporates binding and unbinding of monomers and random phosphate release inside the polymer. It is shown that this theoretical approach provides a microscopic picture of the dynamic instability phenomena of microtubules. The cap size, the concentration dependence of the catastrophe times and the delay before observing catastrophes following a dilution can be quantitatively predicted by this approach in a direct and simple way. Furthermore, the model can be solved analytically to a large extend, thus offering a valuable starting point for more refined studies of microtubules dynamics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.3184v1.pdf"}
{"id": "1103.4233", "abstract": "  The ultracompact low-mass X-ray binary 4U 0513-40 in the globular cluster NGC1851 exhibits large amplitude X-ray flux variations with spectral changes from low/hard to high/soft states which have not been reported previously in other ultracompact X-ray binaries. Using BeppoSAX, CHANDRA and XMM Newton archival data together with recent INTEGRAL observations, we reveal a clear sinusoidal periodic signal with a period of  17 minutes when the source is in a typical high/soft state with a dominant soft thermal component. The periodicity disappears when the source is in a low/hard state and the thermal soft component is not required any more to model the data. These properties indicate the orbital nature of the detected signal and imply an high inclination angle of the binary system (>80). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.4233v1.pdf"}
{"id": "1103.4400", "abstract": "  We study the entanglement entropy in a relativistic quantum field theory for regions which are not included in a single spatial hyperplane. This geometric configuration cannot be treated with the Euclidean time method and the replica trick. Instead, we use a real time method to calculate the entropy for a massive free Dirac field in two dimensions in some approximations. We find some specifically relativistic features of the entropy. First, there is a large enhancement of entanglement due to boosts. As a result, the mutual information between relatively boosted regions does not vanish in the limit of zero volume and large relative boost. We also find extensivity of the information in a deeply Lorentzian regime with large violations of the triangle inequalities for the distances. This last effect is relevant to an interpretation of the amount of entropy enclosed in the Hawking radiation emitted by a black hole. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.4400v1.pdf"}
{"id": "1103.4406", "abstract": "  In this paper, we introduce an efficient interference alignment (IA) algorithm exploiting partially coordinated transmit precoding to improve the number of concurrent interference-free transmissions, i.e., the multiplexing gain, in multicell downlink. The proposed coordination model is such that each base-station simultaneously transmits to two users and each user is served by two base-stations. First, we show in a K-user system operating at the information theoretic upper bound of degrees of freedom (DOF), the generic IA is proper when K ≤ 3, whereas the proposed partially coordinated IA is proper when K ≤ 5. Then, we derive a non-iterative, i.e., one shot, IA algorithm for the proposed scheme when K ≤ 5. We show that for a given latency, the backhaul data rate requirement of the proposed method grows linearly with K. Monte-Carlo simulation results show that the proposed one-shot algorithm offers higher system throughput than the iterative IA at practical SNR levels. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.4406v1.pdf"}
{"id": "1103.5004", "abstract": "  In the last years the Prisoner Dilemma (PD) has become a paradigm for the study of the emergence of cooperation in spatially structured populations. Such structure is usually assumed to be given by a graph. In general, the success of cooperative strategies is associated with the possibility of forming globular clusters, which in turn depends on a feature of the network that is measured by its clustering coefficient. In this work we test the dependence of the success of cooperation with the clustering coefficient of the network, for several different families of networks. We have found that this dependence is far from trivial. Additionally, for both stochastic and deterministic dynamics we have also found that there is a strong dependence on the initial composition of the population. This hints at the existence of several different mechanisms that could promote or hinder cluster expansion. We have studied in detail some of these mechanisms by concentrating on completely ordered networks (large clustering coefficient) or completely random networks (vanishing clustering coefficient). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.5004v1.pdf"}
{"id": "1104.0562", "abstract": "  Wannier function expansions are well suited for the description of photonic- crystal-based defect structures, but constructing maximally localized Wannier functions by optimizing the phase degree of freedom of the Bloch modes is crucial for the efficiency of the approach. We systematically analyze different locality criteria for maximally localized Wannier functions in two- dimensional square and triangular lattice photonic crystals, employing (local) conjugate-gradient as well as (global) genetic-algorithm-based, stochastic methods. Besides the commonly used second moment (SM) locality measure, we introduce a new locality measure, namely the integrated modulus (IM) of the Wannier function. We show numerically that, in contrast to the SM criterion, the IM criterion leads to an optimization problem with a single extremum, thus allowing for fast and efficient construction of maximally localized Wannier functions using local optimization techniques. We also present an analytical formula for the initial choice of Bloch phases, which under certain conditions represents the global maximum of the IM criterion and, thus, further increases the optimization efficiency in the general case. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1104/1104.0562v1.pdf"}
{"id": "1104.1441", "abstract": "  We investigate the electrical transport properties of two hydrogen tautomer configurations of phthalocyanine (H2Pc) connected to cumulene and gold leads. Hydrogen tautomerization affects the electronic state of H2Pc by switching the character of molecular orbitals with the same symmetry close to the Fermi level. The near degeneracy between the HOMO and HOMO-1 leads to pronounced interference effects, causing a large change in current for the two tautomer configuratons, especially in the low-bias regime. Two types of planar junctions are considered: cumulene-H2Pc-cumulene and gold-H2Pc-gold. Both demonstrate prominent difference in molecular conductance between ON and OFF states. In addition, junctions with gold leads show pronounced negative differential resistance (NDR) at high bias voltage, as well as weak NDR at intermediate bias. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1104/1104.1441v2.pdf"}
{"id": "1104.3036", "abstract": "  We consider intrinsic contributions to the spin Hall and spin Nernst effects in a bilayer graphene. The relevant electronic spectrum is obtained from the tight binding Hamiltonian, which also includes the intrinsic spin-orbit interaction. The corresponding spin Hall and spin Nernst conductivities are compared with those obtained from effective Hamiltonians appropriate for states in the vicinity of the Fermi level of a neutral bilayer graphene. Both conductivities are determined within the linear response theory and Green function formalism. The influence of an external voltage between the two atomic sheets is also included. We found transition from the topological spin Hall insulator phase at low voltages to conventional insulator phase at larger voltages. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1104/1104.3036v3.pdf"}
{"id": "1104.3425", "abstract": "  Using a method previously developed, based on the Mellin-Barnes transform, we reconstruct the two-point correlators in the vector, axial, scalar and pseudoscalar channels from the Taylor expansion at q^2=0, the threshold expansion at q^2=4m^2 and the OPE at q^2→-∞, where m is the heavy quark mass. The reconstruction is analytic and systematic and is controlled by an error function which becomes smaller as more terms in those expansions are known. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1104/1104.3425v1.pdf"}
{"id": "1104.4361", "abstract": "  We present calculations of structural and magnetic properties of the iron-pnictide superconductor LaFeAsO including electron-electron correlations. For this purpose we apply a fully charge self-consistent combination of Density-Functional Theory with the Dynamical Mean-Field theory, allowing for the calculation of total energies. We find that the inclusion of correlation effects gives a good agreement of the Arsenic z position with experimental data even in the paramagnetic (high-temperature) phase. Going to low temperatures, we study the formation of the ordered moment in the striped spin-density-wave phase, yielding an ordered moment of about 0.60, again in good agreement with experiments. This shows that the inclusion of correlation effects improves both structural and magnetic properties of LaFeAsO at the same time. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1104/1104.4361v2.pdf"}
{"id": "1104.5359", "abstract": "  A new background rejection strategy for gamma-ray astrophysics with stereoscopic Imaging Atmospheric Cherenkov Telescopes (IACT), based on Monte Carlo (MC) simulations and real background data from the H.E.S.S. [High Energy Stereoscopic System, see [1].] experiment, is described. The analysis is based on a multivariate combination of both previously-known and newly-derived discriminant variables using the physical shower properties, as well as its multiple images, for a total of eight variables. Two of these new variables are defined thanks to a new energy evaluation procedure, which is also presented here. The method allows an enhanced sensitivity with the current generation of ground-based Cherenkov telescopes to be achieved, and at the same time its main features of rapidity and flexibility allow an easy generalization to any type of IACT. The robustness against Night Sky Background (NSB) variations of this approach is tested with MC simulated events. The overall consistency of the analysis chain has been checked by comparison of the real gamma-ray signal obtained from H.E.S.S. observations with MC simulations and through reconstruction of known source spectra. Finally, the performance has been evaluated by application to faint H.E.S.S. sources. The gain in sensitivity as compared to the best standard Hillas analysis ranges approximately from 1.2 to 1.8 depending on the source characteristics, which corresponds to an economy in observation time of a factor 1.4 to 3.2. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1104/1104.5359v1.pdf"}
{"id": "1105.1211", "abstract": "  We quantify the extractable entanglement of excited states of a Lieb-Liniger gas that are obtained from coarse-grained measurements on the ground state in which the boson number in one of two complementary contiguous partitions of the gas is determined. Numerically exact results obtained from the coordinate Bethe ansatz show that the von Neumann entropy of the resulting bipartite pure state increases monotonically with the strength of repulsive interactions and saturates to the impenetrable boson limiting value. We also present evidence indicating that the largest amount of entanglement can be extracted from the most probable projected state having half the number of bosons in a given partition. Our study points to a fundamental difference between the nature of the entanglement in free-bosonic and free-fermionic systems, with the entanglement in the former being zero after projection, while that in the latter (corresponding to the impenetrable boson limit) being non-zero. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.1211v3.pdf"}
{"id": "1105.1671", "abstract": "  In this paper the entanglement and quantum phase transition of the anisotropic s=1/2 XY model are studied by using the quantum renormalization group method. By solving the renormalization equations, we get the trivial fixed point and the untrivial fixed point which correspond to the phase of the system and the critical point, respectively. Then the concurrence between two blocks are calculated and it is found that when the number of the iterations of the renormalziation trends infinity, the concurrence develops two staturated values which are associated with two different phases, i.e., Ising-like and spin-fluid phases. We also investigate the first derivative of the concurrence, and find that there exists non-analytic behaviors at the quantum critical point, which directly associate with the divergence of the correlation length. Further insight, the scaling behaviors of the system are analyzed, it is shown that how the maximum value of the first derivative of the concurrence reaches the infinity and how the critical point is touched as the size of the system becomes large. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.1671v1.pdf"}
{"id": "1105.1855", "abstract": "  In this study, we observe the nonlinear behavior of the two-photon geometric phase for polarization states using time-correlated photons pairs. This phase manifests as a shift of two-photon interference fringes. Under certain arrangements, the geometric phase can vary nonlinearly and become very sensitive to a change in the polarization state. Moreover, it is known that the geometric phase for N identically polarized photons is N times larger than that for one photon. Thus, the geometric phase for two photons can become two times more sensitive to a state change. This high sensitivity to a change in the polarization can be exploited for precision measurement of small polarization variation. We evaluate the signal-to-noise ratio of the measurement scheme using the nonlinear behavior of the geometric phase under technical noise and highlight the practical advantages of this scheme. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.1855v2.pdf"}
{"id": "1105.1903", "abstract": "  The approach applicable for spatially inhomogeneous and time-dependent problems associated with the induced superconductivity in low dimensional electronic systems is developed. This approach is based on the Fano–Anderson model which describes the decay of a resonance state coupled to a continuum. We consider two types of junctions made of a ballistic 2D electron gas placed in a tunnel finite-length contact with a bulk superconducting leads. We calculate the spectrum of the bound states, supercurrent, and the current-voltage curve which show a rich structure due to the presence of induced gap and dimensional quantization. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.1903v1.pdf"}
{"id": "1105.2716", "abstract": "  We have precisely determined the ground state phase diagram of the quantum spin-1 bilinear-biquadratic Heisenberg model on the honeycomb lattice using the tensor renormalization group method. We find that the ferromagnetic, ferroquadrupolar, and a large part of the antiferromagnetic phases are stable against quantum fluctuations. However, around the phase where the ground state is antiferroquadrupolar ordered in the classical limit, quantum fluctuations suppress completely all magnetic orders, leading to a plaquette order phase which breaks the lattice symmetry but preserves the spin SU(2) symmetry. On the evidence of our numerical results, the quantum phase transition between the antiferromagnetic phase and the plaquette phase is found to be either a direct second order or a very weak first order transition. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.2716v3.pdf"}
{"id": "1105.2828", "abstract": "  We develop a Fermionic Chern-Simons (CS) theory for the fractional quantum Hall effect in monolayer graphene with SU(4) symmetry, arising from the spin and the valley degrees of freedom, which involves four distinct CS gauge fields. We choose the corresponding elements of the CS coupling matrix such that an even number of spin and valley quantum number dependent flux quanta is attached to all electrons and that any electron with a given spin and valley quantum number sees an integer number of flux attached to other electrons with different (spin and valley) quantum numbers. Using this CS matrix, we obtain a list of possible fractional quantum Hall states that might occur in graphene and propose wavefunctions for those states. Our analysis also applies to fractional quantum Hall states of both bilayer quantum Hall systems without spin polarization and bilayer spin polarized graphene. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.2828v1.pdf"}
{"id": "1105.3012", "abstract": "  The Kosterlitz-Thouless transition for the spin 1/2 Heisenberg chain with the next-to-the-nearest-neighbor interaction is investigated in the context of an infinite matrix product state algorithm, which is a generalization of the infinite time-evolving block decimation algorithm [G. Vidal, Phys. Rev. Lett. 98, 070201 (2007)] to accommodate both the next-to-the-nearest-neighbor interaction and spontaneous dimerization. It is found that, in the critical regime, the algorithm automatically leads to infinite degenerate ground-state wave functions, due to the finiteness of the truncation dimension. This results in pseudo symmetry spontaneous breakdown, as reflected in a bifurcation in the ground-state fidelity per lattice site. In addition, this allows to introduce a pseudo-order parameter to characterize the Kosterlitz-Thouless transition. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.3012v1.pdf"}
{"id": "1105.3350", "abstract": "  We have obtained accurate near-infrared photometry of the Tip of the Red Giant Branches in the Local Group galaxies Sculptor, NGC 6822, NGC 3109, IC 1613 and WLM. We have used the derived TRGB magnitudes together with the absolute magnitude calibration of the near-infrared TRGB magnitude of Valenti, Ferraro and Origlia to determine the distances of these five galaxies. The statis- tical errors in the distance moduli are typically 4", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.3350v1.pdf"}
{"id": "1105.4787", "abstract": "  We study the effects of an elastic crust on the oscillation spectrum of superfluid neutron stars. Within the two fluid formalism, we consider Newtonian stellar models that include the relevant constituents of a mature neutron stars. The core is formed by a mixture of superfluid neutrons and a conglomerate of charged particles, while the inner crust is described by a lattice of nuclei permeated by superfluid neutrons. We linearise the Poisson and the conservation equations of nonrotating superfluid stars and study the effects of elasticity, entrainment and composition stratification on the shear and acoustic modes. In both the core and the crust, the entrainment is derived from recent results for the nucleon effective mass. Solving the perturbation equations as an eigenvalue problem, we find that the presence of superfluid neutrons in the crust and their large effective mass may have significant impact on the star's oscillation spectrum. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.4787v1.pdf"}
{"id": "1105.5666", "abstract": "  This paper presents reaction cross section predictions. These predictions are the result of a continuous pipeline which originates from a microscopic nuclear interaction. Density parameters and effective nucleon-nucleon cross sections (both involved in the reaction calculations) are by-products of the same equation of state. First, we perform tests of sensitivity to medium effects using reactions involving 208-Pb, a stable but weakly isospin-asymmetric nucleus. We also show predictions for collisions of some neutron-rich isotopes of Calcium and Argon. We observe significant sensitivity of the reaction cross section to medium effects but very weak sensitivity to inclusion of isospin asymmetry in the effective nucleon-nucleon cross sections. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.5666v1.pdf"}
{"id": "1105.5793", "abstract": "  The excitation of multiple surface-plasmon-polariton (SPP) waves of different linear polarization states and phase speeds by a surface-relief grating formed by a metal and a rugate filter, both of finite thickness, was studied theoretically, using rigorous coupled-wave-analysis. The incident plane wave can be either p or s polarized. The excitation of SPP waves is indicated by the presence of those peaks in the plots of absorbance vs. the incidence angle that are independent of the thickness of the rugate filter. The absorbance peaks representing the excitation of s-polarized SPP waves are narrower than those representing p-polarized SPP waves. Two incident plane waves propagating in different directions may excite the same SPP wave. A line source could excite several SPP waves simultaneously. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.5793v1.pdf"}
{"id": "1106.0145", "abstract": "  Self consistent renormalization theory of itinerant ferromagnets is used to calculate the Curie temperature of clusters down to approximately 100 atoms in size. In these clusters the electrons responsible for the magnetic properties are assumed to be (weakly) itinerant. It is shown that the Curie temperature can be larger than in the bulk. The effect originates from the phenomenon of level repulsion in chaotic quantum systems, which suppresses spin fluctuations. Since the latter destroy the magnetic order the resulting Curie temperature increases, contrary to expectations of the naive Stoner picture. The calculations are done assuming that the energy levels of the cluster are described by the Gaussian Orthogonal Ensemble of random matrix theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.0145v1.pdf"}
{"id": "1106.0419", "abstract": "  We present here the exact solution of an infinite range, discrete, opinion formation model. The model shows an active-absorbing phase transition, similar to that numerically found in its recently proposed continuous version (Lallouache et al., Phys. Rev E 82, 056112 (2010)). Apart from the two-agent interactions here we also report the effect of having three agent interactions. The phase diagram has a continuous transition line (two agent interaction dominated) and a discontinuous transition line (three agent interaction dominated) separated by a tricritical point. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.0419v3.pdf"}
{"id": "1106.0988", "abstract": "  Electromagnetically-induced transparency has become an important tool to control the optical properties of dense media. However, in a broad class of systems, the interplay between inhomogeneous broadening and the existence of several excited levels may lead to a vanishing transparency. Here, by identifying the underlying physical mechanisms resulting in this effect, we show that transparency can be strongly enhanced. We thereby demonstrate a 5-fold enhancement in a room-temperature vapor of alkali-metal atoms via a specific shaping of the atomic velocity distribution. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.0988v3.pdf"}
{"id": "1106.1025", "abstract": "  We study the Gauss-Bonnet (GB) holographic superconductors in the presence of an external magnetic field. We describe the phenomena away from the probe limit. We derive the critical magnetic field of the GB holographic superconductors with backreaction. Our analytical approach matches the numerical calculations. We calculate the backreaction corrections up to first order of O(κ^2=8π G) to the critical temperature T_C and the critical magnetic field B_C for a GB superconductor. We show that the GB coupling α makes the condensation weaker but the backreaction corrections O(κ^2) make the critical magnetic field stronger. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.1025v3.pdf"}
{"id": "1106.1960", "abstract": "  We propose a one-dimensional model of spinor bosons with SU(2) symmetry and a two-body finite range Gaussian interaction potential. We show that the model is exactly solvable when the width of the interaction potential is much smaller compared to the inter-particle separation. This model is then solved via the asymptotic Bethe ansatz technique. The ferromagnetic ground state energy and chemical potential are derived analytically. We also investigate the effects of a finite range potential on the density profiles through local density approximation. Finite range potentials are more likely to lead to quasi Bose-Einstein condensation than zero range potentials. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.1960v2.pdf"}
{"id": "1106.2007", "abstract": "  Complex networks are important tools for analyzing the information flow in many aspects of nature and human society. Using data from the microblogging service Twitter, we study networks of correlations in the appearance of words from three different categories, international brands, nouns and US major cities. We create networks where the strength of links is determined by a similarity measure based on the rate of coappearance of words. In comparison with the null model, where words are assumed to be uncorrelated, the heavy-tailed distribution of pair correlations is shown to be a consequence of modules of words representing similar entities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.2007v2.pdf"}
{"id": "1106.2374", "abstract": "  Recent analyses of datasets acquired at the Brookhaven National Laboratory and at the Physikalisch-Technische Bundesanstalt both show evidence of pronounced annual variations, suggestive of a solar influence. However, the phases of decay-rate maxima do not correspond precisely to the phase of minimum Sun-Earth distance, as might then be expected. We here examine the hypothesis that decay rates are influenced by an unknown solar radiation, but that the intensity of the radiation is influenced not only by the variation in Sun-Earth distance, but also by a possible North-South asymmetry in the solar emission mechanism. We find that this can lead to phases of decay-rate maxima in the range 0 to 0.183 or 0.683 to 1 (September 6 to March 8) but that, according to this hypothesis, phases in the range 0.183 to 0.683 (March 8 to September 6) are \"forbidden.\" We find that phases of the three datasets here analyzed fall in the allowed range. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.2374v1.pdf"}
{"id": "1106.2940", "abstract": "  We compute the dynamical polarization function for a graphene antidot lattice in the random-phase approximation. The computed polarization functions display a much more complicated structure than what is found for pristine graphene (even when evaluated beyond the Dirac-cone approximation); this reflects the miniband structure and the associated van Hove singularities of the antidot lattice. The polarization functions depend on the azimuthal angle of the q-vector. We develop approximations to ease the numerical work, and critically evaluate the performance of the various schemes. We also compute the plasmon dispersion law, and find an approximate square-root dependence with a suppressed plasmon frequency as compared to doped graphene. The plasmon dispersion is nearly isotropic, and the developed approximation schemes agree well with the full calculation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.2940v1.pdf"}
{"id": "1106.3407", "abstract": "  In low-density nuclear matter which is relevant to the crust region of neutron stars and collapsing stage of supernovae, non-uniform structures called \"nuclear pasta\" are expected. So far, most works on nuclear pasta have used the Wigner-Seitz cell approximation with anzats about the geometrical structures like droplet, rod, slab and so on. We perform fully three-dimensional calculation of non-uniform nuclear matter for some cases with fixed proton ratios and in beta-equilibrium based on the relativistic mean-field model and the Thomas-Fermi approximation. In our calculation typical pasta structures are observed. However, there appears some difference in the density region of each pasta structure. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.3407v1.pdf"}
{"id": "1107.0075", "abstract": "  We have developed an unifying tight-binding Hamiltonian that can account for the electronic properties of recently proposed Si-based nanostructures, namely, Si graphene-like sheets and Si nanotubes. We considered the sp^3s^* and sp^3 models up to first- and second-nearest neighbors, respectively. Our results show that the Si graphene-like sheets considered here are metals or zero-gap semiconductors, and that the corresponding Si nanotubes follow the so-called Hamada's rule [Phys. Rev. Lett. 68, 1579 1992]. Comparison to a recent ab initio calculation is made. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.0075v1.pdf"}
{"id": "1107.1248", "abstract": "  A mathematical model is introduced which describes the dissipation of electrons in lightly doped semi-conductors. The dissipation operator is proved to be densely defined and positive and to generate a Markov semigroup of operators. The spectrum of the dissipation operator is studied and it is shown that zero is a simple eigenvalue, which makes the equilibrium state unique. Also it is shown that there is a gap between zero and the rest of its spectrum which makes the return to equilibrium exponentially fast in time. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.1248v1.pdf"}
{"id": "1107.1385", "abstract": "  Due to the complex characteristics of bottle-brush polymers, it became a challenge to develop an efficient algorithm for studying such macromolecules under various solvent conditions or some constraints in the space by using computer simulations. In the limit of a bottle-brush polymer with a rather stiff backbone (straight rigid backbone), we generalize the variant of the biased chain growth algorithm, the pruned-enriched Rosenbluth method, for simulating polymers with complex architecture, from star polymers to bottle-brush polymers, on the simple cubic lattice. With the high statistics of our Monte Carlo results, we check the theoretical predictions of side chain behavior and radial monomer density profile. For the comparison of the experimental data for bottle-brush polymers with a flexible backbone and flexible side chains, based on the bond fluctuation model we propose another fast Monte Carlo algorithm combining the local moves, the pivot move, and an adjustable simulation lattice box. By monitoring the autocorrelation functions of gyration radii for the side chains and for the backbone, we see that for fixed side chain length there is no change in the behavior of these two functions as the backbone length increases. Our extensive results cover the range which is accessible for the comparison to experimental data and for the checking of the theoretically predicted scaling laws. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.1385v1.pdf"}
{"id": "1107.2075", "abstract": "  The chemical composition of a protoplanetary disk is determined not only by in situ chemical processes during the disk phase, but also by the history of the gas and dust before it accreted from the natal envelope. In order to understand the disk's chemical composition at the time of planet formation, especially in the midplane, one has to go back in time and retrace the chemistry to the molecular cloud that collapsed to form the disk and the central star. Here we present a new astrochemical model that aims to do just that. The model follows the core collapse and disk formation in two dimensions, which turns out to be a critical upgrade over older collapse models. We predict chemical stratification in the disk due to different physical conditions encountered along different streamlines. We argue that the disk-envelope accretion shock does not play a significant role for the material in the disk at the end of the collapse phase. Finally, our model suggests that complex organic species are formed on the grain surfaces at temperatures of 20 to 40 K, rather than in the gas phase in the T>100 K hot corino. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.2075v1.pdf"}
{"id": "1107.2184", "abstract": "  The generalized density matrix (GDM) method is used to calculate microscopically the parameters of the collective Hamiltonian. Higher order anharmonicities are obtained consistently with the lowest order results, the mean field [Hartree-Fock-Bogoliubov (HFB) equation] and the harmonic potential [quasiparticle random phase approximation (QRPA)]. The method is applied to soft spherical nuclei, where the anharmonicities are essential for restoring the stability of the system, as the harmonic potential becomes small or negative. The approach is tested in three models of increasing complexity: the Lipkin model, model with factorizable forces, and the quadrupole plus pairing model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.2184v1.pdf"}
{"id": "1108.0528", "abstract": "  A detailed description and theoretical analysis of experiments achieving coherent coupling between an ion Coulomb crystal and an optical cavity field are presented. The various methods used to measure the coherent coupling rate between large ion Coulomb crystals in a linear quadrupole radiofrequency ion trap and a single field mode of a moderately high-finesse cavity are described in detail. Theoretical models based on a semiclassical approach are applied in assessment of the experimental results of [P. F. Herskind et al., Nature Phys. 5, 494 (2009)] and of complementary new measurements. Generally, a very good agreement between theory and experiments is obtained. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.0528v3.pdf"}
{"id": "1108.2546", "abstract": "  We present a semiclassical model of an atom moving in the evanescent field of a microtoroidal resonator. Atoms falling through whispering-gallery modes can achieve strong, coherent coupling with the cavity at distances of approximately 100 nanometers from the surface; in this regime, surface-induced Casmir-Polder level shifts become significant for atomic motion and detection. Atomic transit events detected in recent experiments are analyzed with our simulation, which is extended to consider atom trapping in the evanescent field of a microtoroid. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.2546v1.pdf"}
{"id": "1108.2725", "abstract": "  We present a microlensing analysis of 61 Chandra observations of 14 quadruply lensed quasars. X-ray flux measurements of the individual quasar images give a clean determination of the microlensing effects in the lensing galaxy and thus offer a direct assessment of the local fraction of stellar matter making up the total integrated mass along the lines of sight through the lensing galaxy. A Bayesian analysis of the ensemble of lensing galaxies gives a most likely local stellar fraction of 7", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.2725v2.pdf"}
{"id": "1108.5310", "abstract": "  We study macroscopic quantum tunneling of interfaces separating normal and superconducting regions in type-I superconductors. Mathematical model is developed, that describes dissipative quantum escape of a two-dimensional manifold from a planar potential well. It corresponds to, e.g., a current-driven quantum depinning of the interface from a grain boundary or from artificially manufactured pinning layer. Effective action is derived and instantons of the equations of motion are investigated. Crossover between thermal activation and quantum tunneling is studied and the crossover temperature is computed. Our results, together with recent observation of non-thermal low-temperature magnetic relaxation in lead, suggest possibility of a controlled measurement of quantum depinning of the interface in a type-I superconductor. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.5310v1.pdf"}
{"id": "1108.5811", "abstract": "  The thermal conductance in graphene nanoribbon with a vacancy or silicon point defect (substitution of C by Si atom) is investigated by non-equilibrium Green's function (NEGF) formalism combined with first-principle calculations density-functional theory with local density approximation. An efficient correction to the force constant matrix is presented to solve the conflict between the long-range character of the ab initio approach and the first-nearest-neighboring character of the NEGF scheme. In nanoribbon with a vacancy defect, the thermal conductance is very sensitive to the position of the vacancy defect. A vacancy defect situated at the center of the nanoribbon generates a saddle-like surface, which greatly reduces the thermal conductance by strong scattering to all phonon modes; while an edge vacancy defect only results in a further reconstruction of the edge and slightly reduces the thermal conductance. For the Si defect, the position of the defect plays no role for the value of the thermal conductance, since the defective region is limited within a narrow area around the defect center. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.5811v1.pdf"}
{"id": "1109.0176", "abstract": "  The momentum spectra of K+ produced at small angles in proton-proton and proton-deuteron collisions have been measured at four beam energies, 1.826, 1.920, 2.020, and 2.650 GeV, using the ANKE spectrometer at COSY-Juelich. After making corrections for Fermi motion and shadowing, the data indicate that K+ production near threshold is stronger in pp- than in pn-induced reactions. However, most of this difference could be made up by the unobserved K0 production in the pn case. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1109/1109.0176v1.pdf"}
{"id": "1109.0807", "abstract": "  Consider a large Boolean network with a feed forward structure. Given a probability distribution on the inputs, can one find, possibly small, collections of input nodes that determine the states of most other nodes in the network? To answer this question, a notion that quantifies the determinative power of an input over the states of the nodes in the network is needed. We argue that the mutual information (MI) between a given subset of the inputs X = X_1, ..., X_n of some node i and its associated function f_i(X) quantifies the determinative power of this set of inputs over node i. We compare the determinative power of a set of inputs to the sensitivity to perturbations to these inputs, and find that, maybe surprisingly, an input that has large sensitivity to perturbations does not necessarily have large determinative power. However, for unate functions, which play an important role in genetic regulatory networks, we find a direct relation between MI and sensitivity to perturbations. As an application of our results, we analyze the large-scale regulatory network of Escherichia coli. We identify the most determinative nodes and show that a small subset of those reduces the overall uncertainty of the network state significantly. Furthermore, the network is found to be tolerant to perturbations of its inputs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1109/1109.0807v2.pdf"}
{"id": "1109.0981", "abstract": "  We present a result of X-ray supernovae (SNe) survey using the Swift satellite public archive. An automatic searching program was designed to search X-ray SNe among all of the Swift archival observations between November 2004 and February 2011. Using the C++ program, 24 X-ray detectable supernovae have been found in the archive and 3 of them were newly-discovered in X-rays which are SN 1986L, SN 2003lx, and SN 2007od. In addition, SN 2003lx is a Type Ia supernova which may be the second X-ray detectable Type Ia after SN 2005ke (Immler et al. 2006). Calibrated data of luminous type Ib/c supernovae was consistent to the X-ray emission model done by Chevalier     Fransson (1994). Statistics about the luminosities and hardness ratio have been done to purpose of getting the X-ray emission features of the X-ray supernovae. The results from this work help investigating the X-ray evolution of SNe and developing similar X-ray SNe surveys in various X-rays missions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1109/1109.0981v1.pdf"}
{"id": "1109.3204", "abstract": "  The Green function method developed in Ref.[S. B. Chernyshuk and B. I. Lev, Phys. Rev. E 81, 041707 (2010)] is used to describe elastic interactions between axially symmetric colloidal particles in the nematic cell in the presence of the external electric or magnetic field. General formulas for dipole-dipole, dipole-quadrupole and quadrupole-quadrupole interactions in the homeotropic and planar nematic cells with parallel and perpendicular field orientations are obtained. A set of new results has been predicted: 1) Deconfinement effect for dipole particles in the homeotropic nematic cell with negative dielectric anisotropy Δϵ<0 and perpendicular to the cell electric field, when electric field is approaching it's Frederiks threshold value E⇒ E_c. This means cancellation of the confinement effect found in Ref. [M.Vilfan et al. Phys.Rev.Lett. 101, 237801, (2008)] for dipole particles near the Frederiks transition while it remains for quadrupole particles. 2) New effect of attraction and stabilization of the particles along the electric field parallel to the cell planes in the homeotropic nematic cell with Δϵ<0 . The minimun distance between two particles depends on the strength of the field and can be ordinary for . 3) Attraction and repulsion zones for all elastic interactions are changed dramatically under the action of the external field. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1109/1109.3204v1.pdf"}
{"id": "1109.4369", "abstract": "  To gain some insight into electrochemical activity of dielectric colloids of technical and biomedical interest we investigate a model of dielectric nanosolution whose micro-constitution is dominated by dipolarions – positively and negatively charged spherically symmetric nano-structures composed of ionic charge surrounded by cloud of radially polarized dipoles of electrically neutral molecules of solvent. Combing the standard constitutive equations of an isotropic dielectric liquid with Maxwell equation of electrostatics and presuming the Boltzmann shape of the particle density of bound-charge we derive equation for the in-medium electrostatic field. Particular attention is given to numerical analysis of obtained analytic solutions of this equation describing the exterior fields of dipolarions with dipolar atmospheres of solvent molecules endowed with either permanent or field-induced dipole moments radially polarized by central symmetric field of counterions. The presented computations show that the electric field shielding of dipolarions in dielectric nanosolutions is quite different from that of counterionic nano-complexes of Debye-Hückel theory of electrolytes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1109/1109.4369v1.pdf"}
{"id": "1109.6753", "abstract": "  We study the effect of external driving on the two level systems (TLSs) assumed to be a major obstacle in increasing the coherence time of solid state Josephson-junction qubits. We find, by use of a Bloch-Redfield approach, that external driving has two major effects on the TLS. The first is increased fluctuations between the two states of the TLS, the significance of this effect compared to thermal fluctuations depend on the energy splitting of the TLS compared to temperature. The second effect is a reduction in the intensity of the noise spectrum at low frequencies, and at the same time an increase in intensity around the renormalized Rabi frequency of the TLS, the driving frequency and at beatings between these two frequencies. Finally we study the ensemble averaged noise spectrum for a typical distribution of TLSs known to give origin to ∝ 1/f noise. We find that strong driving leads to reduced noise at low frequencies, and therefore to an increased dephasing time T_2^Q of the qubit. However this effect is exponentially suppressed when the driving frequency is large compared to temperature, as we typically find for Josephson qubits. We suggest that external driving at frequencies much lower than the qubit frequency might be used in order to enhance the the qubit coherence time. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1109/1109.6753v1.pdf"}
{"id": "1110.0547", "abstract": "  The temperature structure of Be star circumstellar disks at the sub-solar metallicity appropriate to the Small Magellanic Cloud (SMC) is investigated. It is found that for central stars of the same spectral type, Be star disks in the SMC are systematically hotter by several thousand degrees compared to Milky Way (MW) disks with the same density structure. For early spectral types (B0e - B3e), this results in systematically smaller Hα equivalent widths for Be stars in the SMC. The implication of this result on Be star frequency comparisons between MW and SMC clusters is shown to be a 5 - 10", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.0547v1.pdf"}
{"id": "1110.1976", "abstract": "  In this paper, we consider the problem of exploring structural regularities of networks by dividing the nodes of a network into groups such that the members of each group have similar patterns of connections to other groups. Specifically, we propose a general statistical model to describe network structure. In this model, group is viewed as hidden or unobserved quantity and it is learned by fitting the observed network data using the expectation-maximization algorithm. Compared with existing models, the most prominent strength of our model is the high flexibility. This strength enables it to possess the advantages of existing models and overcomes their shortcomings in a unified way. As a result, not only broad types of structure can be detected without prior knowledge of what type of intrinsic regularities exist in the network, but also the type of identified structure can be directly learned from data. Moreover, by differentiating outgoing edges from incoming edges, our model can detect several types of structural regularities beyond competing models. Tests on a number of real world and artificial networks demonstrate that our model outperforms the state-of-the-art model at shedding light on the structural features of networks, including the overlapping community structure, multipartite structure and several other types of structure which are beyond the capability of existing models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.1976v1.pdf"}
{"id": "1110.1983", "abstract": "  The Semiconductor Tracker (SCT) is a silicon strip detector and one of the key precision tracking devices in the Inner Detector of the ATLAS experiment at CERN LHC. The completed SCT has been installed inside the ATLAS experimental cavern since 2007 and has been operational since then. Calibration data has been taken regularly and analyzed to determine the performance of the system. In this paper the current status of the SCT is reviewed, including results from data-taking periods in 2010 and 2011. We report on the operation of the detector including overviews on services, connectivity and observed problems. The main emphasis is given to the performance of the SCT with the LHC in collision mode and to the performance of individual electronic components. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.1983v1.pdf"}
{"id": "1110.2413", "abstract": "  Three software systems, ERCS08, ISICS 2011 and Šmit's code, that implement theoretical calculations of inner shell ionization cross sections by proton impact, are validated with respect to experimental data. The accuracy of the cross sections they generate is quantitatively estimated and inter-compared through statistical methods. Updates and extensions of a cross section data library relevant to PIXE simulation with Geant4 are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.2413v1.pdf"}
{"id": "1110.2636", "abstract": "  Hidden sectors in connection with GeV-scale dark forces and dark matter are not only a common feature of physics beyond the Standard Model such as string theory and SUSY but are also phenomenologically of great interest regarding recent astrophysical observations. The hidden photon in particular is also searched for and constrained by laboratory experiments, the current status of which will be presented here. Furthermore, several models of hidden sectors containing in addition a dark matter particle will be examined regarding their consistency with the dark matter relic abundance and direct detection experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.2636v2.pdf"}
{"id": "1110.3721", "abstract": "  Recently much interest has been directed towards designing setups that achieve realistic loss thresholds for decisive tests of local realism, in particular in the optical regime. We analyse the feasibility of such Bell tests based on a W-state shared between multiple parties, which can be realised for example by a single photon shared between spatial modes. We develop a general error model to obtain thresholds on the efficiencies required to violate local realism, and also consider two concrete optical measurement schemes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.3721v1.pdf"}
{"id": "1110.5808", "abstract": "  Since the LHC running season 2010, the TOTEM Roman Pots (RPs) are fully operational and serve for collecting elastic and diffractive proton-proton scattering data. Like for other moveable devices approaching the high intensity LHC beams, a reliable and precise control of the RP position is critical to machine protection. After a review of the RP movement control and position interlock system, the crucial task of alignment will be discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.5808v1.pdf"}
{"id": "1110.6839", "abstract": "  The mid-rapidity charged particle multiplicities in pp and AA collisions at LHC energies are described in the framework of a generalized eikonal model with shadowing corrections incorporated in AA. We show that the pp data require a Pomeron intercept close to 1.2, higher than the conventional one close to 1.1. An s^0.11 energy dependence is obtained in the LHC range and beyond. The size and centrality dependence of the AA multiplicity at √(s) = 2.76 TeV is reproduced and its energy dependence is predicted. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.6839v2.pdf"}
{"id": "1111.0935", "abstract": "  Using Bayesian experimental design techniques, we have shown that for a single two-level quantum mechanical system under strong (projective) measurement, the dynamical parameters of a model Hamiltonian can be estimated with exponentially improved accuracy over offline estimation strategies. To achieve this, we derive an adaptive protocol which finds the optimal experiments based on previous observations. We show that the risk associated with this algorithm is close to the global optimum, given a uniform prior. Additionally, we show that sampling at the Nyquist rate is not optimal. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.0935v1.pdf"}
{"id": "1111.1313", "abstract": "  Critical behavior of soft repulsive particles after quench of temperature near the jamming trasition is numerically investigated. It is found that the plateau of the mean square displacement of tracer particles and the pressure satisfy critical scaling laws. The critical density for the jamming transition depends on the protocol to prepare the system, while the values of the critical exponents which are consistent with the prediction of a phenomenology are independent of the protocol. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.1313v6.pdf"}
{"id": "1111.4521", "abstract": "  In this paper, we present a method to measure the frequency and the frequency change rate of a digital signal. This method consists of three consecutive algorithms: frequency interpolation, phase differencing, and a third algorithm specifically designed and tested by the authors. The succession of these three algorithms allowed a 5 parts in 10^10 resolution in frequency determination. The algorithm developed by the authors can be applied to a sampled scalar signal such that a model linking the harmonics of its main frequency to the underlying physical phenomenon is available. This method was developed in the framework of the Gravity Probe B (GP-B) mission. It was applied to the High Frequency (HF) component of GP-B's Superconducting QUantum Interference Device (SQUID) signal, whose main frequency fz is close to the spin frequency of the gyroscopes used in the experiment. A 30 nHz resolution in signal frequency and a 0.1 pHz/sec resolution in its decay rate were achieved out of a succession of 1.86 second-long stretches of signal sampled at 2200 Hz. This paper describes the underlying theory of the frequency measurement method as well as its application to GP-B's HF science signal. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.4521v1.pdf"}
{"id": "1111.4834", "abstract": "  We illustrate using a quantum system the principle of a cryptographic switch, in which a third party (Charlie) can control to a continuously varying degree the amount of information the receiver (Bob) receives, after the sender (Alice) has sent her information. Suppose Charlie transmits a Bell state to Alice and Bob. Alice uses dense coding to transmit two bits to Bob. Only if the 2-bit information corresponding to choice of Bell state is made available by Charlie to Bob can the latter recover Alice's information. By varying the information he gives, Charlie can continuously vary the information recovered by Bob. The performance of the protocol subjected to the squeezed generalized amplitude damping channel is considered. We also present a number of practical situations where a cryptographic switch would be of use. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.4834v1.pdf"}
{"id": "1111.5368", "abstract": "  The project of constructing a complete NLO-level Parton Shower Monte Carlo for the QCD processes developed in IFJ PAN in Krakow is reviewed. Four issues are discussed: (1) the extension of the standard inclusive collinear factorization into a new, fully exclusive scheme; (2) reconstruction of the LO Parton Shower in the new scheme; (3) inclusion of the exclusive NLO corrections into the hard process and (4) inclusion of the exclusive NLO corrections into the evolution (ladder) part. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.5368v1.pdf"}
{"id": "1112.0419", "abstract": "  The interplay and coexistence of superconducting, magnetic and structural order parameters in NaFe1-xCoxAs has been studied using SQUID magnetometry, muon-spin rotation and synchrotron x-ray powder diffraction. Substituting Fe by Co weakens the ordered magnetic state through both a suppression of T_N and a reduction in the size of the ordered moment. Upon further substitution of Fe by Co the high sensitivity of the muon as a local magnetic probe reveals a magnetically disordered phase, in which the size of the moment continues to decrease and falls to zero around the same point at which the magnetically-driven structural distortion is no longer resolvable. Both magnetism and the structural distortion are weakened as the robust superconducting state is established. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.0419v1.pdf"}
{"id": "1112.0615", "abstract": "  In ultrathin ferromagnets deposited on metallic substrates, excitation of precessional motion of the spins produces a spin current in the substrate that transports angular momentum out of the film. This phenomenon is referred to as spin pumping, and is a source of damping of the spin motion. Spin pumping enters importantly in the description of spin dynamics in other nanoscale and subnanoscale systems as well. In this paper, we present an approach based on the Kubo formalism that allows the explicit calculation of this spin current and its spatial variation. We use the formalism to explore features of the spin current generated by spin motions in a simple model system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.0615v1.pdf"}
{"id": "1112.1381", "abstract": "  We check how the change in surface conditions between the Sun and red giant branch stars changes the characteristic surface convection length scale to be used in models. We investigate the question in the case of the mixing length theory and of the phenomenology of full spectrum of turbulence. For the observational part, we rely on independent measurements of effective temperatures and interferometric radii of nearby red giants. We find that the local red giant branch cannot be explained taking into account the solar calibrated convective length scale. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.1381v1.pdf"}
{"id": "1112.1515", "abstract": "  We consider a single electron traveling along a strictly one-dimensional quantum wire interacting with another electron in a quantum ring capacitively coupled to the wire. We develop an exact numerical method for treating the scattering problem within the stationary two-electron wave function picture. The considered process conserves the total energy but the electron within the wire passes a part of its energy to the ring. We demonstrate that the inelastic scattering results in both magnetic asymmetry of the transfer probability and a turnstile action of the ring on the electrons traveling separately along the ring. We demonstrate that the inelastic backscattering and / or inelastic electron transfer can be selectively eliminated from the process by inclusion of an energy filter into the wire in form of a double barrier system with the resonant energy level tuned to the energy of the incident electron. We demonstrate that the magnetic symmetry is restored when the inelastic backscattering is switched o?, and the turnstile character of the ring is removed when the energy transfer to the ring is excluded for both transferred and backscattered electron waves. We discuss the relation of the present results to the conductance systems based on the electron gas. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.1515v1.pdf"}
{"id": "1112.2346", "abstract": "  We consider excitons in a quantum dot as q-deformed systems. Interaction of some excitonic systems with one cavity mode is considered. Dynamics of the system is obtained by diagonalizing total Hamiltonian and emission spectrum of quantum dot is derived. Physical consequences of q-deformed exciton on emission spectrum of quantum dot is given. It is shown that when the exciton system deviates from Bose statistics, emission spectra will become multi peak. With our investigation we try to find the origin of the q-deformation of exciton. The optical response of excitons, which affected by the nonlinear nature of q-deformed systems, up to the second order of approximation is calculated and absorption spectra of the system is given. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.2346v1.pdf"}
{"id": "1112.2366", "abstract": "  Searches for planets via gravitational lensing have focused on cases in which the projected separation, a, between planet and star is comparable to the Einstein radius, R_E. This paper considers smaller orbital separations and demonstrates that evidence of close-orbit planets can be found in the low-magnification portion of the light curves generated by the central star. We develop a protocol to discover hot Jupiters as well as Neptune-mass and Earth-mass planets in the stellar habitable zone. When planets are not discovered, our method can be used to quantify the probability that the lens star does not have planets within specified ranges of the orbital separation and mass ratio. Nearby close-orbit planets discovered by lensing can be subject to follow-up observations to study the newly-discovered planets or to discover other planets orbiting the same star. Careful study of the low-magnification portions of lensing light curves should produce, in addition to the discoveries of close-orbit planets, definite detections of wide-orbit planets through the discovery of \"repeating\" lensing events. We show that events exhibiting extremely high magnification can effectively be probed for planets in close, intermediate, and wide distance regimes simply by adding several-time-per-night monitoring in the low-magnification wings, possibly leading to gravitational lensing discoveries of multiple planets occupying a broad range of orbits, from close to wide, in a single planetary system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.2366v1.pdf"}
{"id": "1112.3164", "abstract": "  We review the problem of state reconstruction in classical and in quantum physics, which is rarely considered at the textbook level. We review a method for retrieving a classical state in phase space, similar to that used in medical imaging known as Computer Aided Tomography. We explain how this method can be taken over to quantum mechanics, where it leads to a description of the quantum state in terms of the Wigner function which, although may take on negative values, plays the role of the probability density in phase space in classical physics. We explain another approach to quantum state reconstruction based on the notion of Mutually Unbiased Bases, and indicate the relation between these two approaches. Both are for a continuous, infinite-dimensional Hilbert space. We then study the finite-dimensional case and show how the second method, based on Mutually Unbiased Bases, can be used for state reconstruction. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.3164v1.pdf"}
{"id": "1112.4546", "abstract": "  We employ molecular dynamic simulations to study the reduction process of graphene-oxide (GO) in a chemically active environment enriched with hydrogen. We examine the concentration and pressure of hydrogen gas as a function of temperature in which abstraction of oxygen is possible with minimum damage to C-sp^2 bonds hence preserving the integrity of the graphene sheet. Through these studies we find chemical pathways that demonstrate beneficiary mechanisms for the quality of graphene including formation of water as well as suppression of carbonyl pair holes in favor of hydroxyl and epoxy formation facilitated by hydrogen gas in the environment. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.4546v1.pdf"}
{"id": "1112.4841", "abstract": "  Thermal instability (TI) can strongly affect the structure and dynamics of the interstellar medium (ISM) in the Milky Way and other disk galaxies. Thermal conduction plays an important role in the TI by stabilizing small scales and limiting the size of the smallest condensates. In the magnetized ISM, however, heat is conducted anisotropically (primarily along magnetic field lines). We investigate the effects of anisotropic thermal conduction on the nonlinear regime of the TI by performing two-dimensional magnetohydrodynamic simulations. We present models with magnetic fields of different initial geometries and strengths, and compare them to hydrodynamic models with isotropic conduction. We find anisotropic conduction does not significantly alter the overall density and temperature statistics in the saturated state of the TI. However, it can strongly affect the shapes and sizes of cold clouds formed by the TI. For example, for uniform initial fields long filaments of cold gas are produced that are reminiscent of some observed HI clouds. For initially tangled fields, such filaments are not produced. We also show that anisotropic conduction suppresses turbulence generated by evaporative flows from the surfaces of cold blobs, which may have implications for mechanisms for driving turbulence in the ISM. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.4841v1.pdf"}
{"id": "1112.5003", "abstract": "  We show how the onset of a non-Slater antiferromagnetic ordering in a correlated material can be detected by optical spectroscopy. Using dynamical mean-field theory we identify two distinctive features: The antiferromagnetic ordering is associated with an enhanced spectral weight above the optical gap, and well separated spin-polaron peaks emerge in the optical spectrum. Both features are indeed observed in LaSrMnO_4 [Gössling et al., Phys. Rev. B 77, 035109 (2008)] ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.5003v1.pdf"}
{"id": "1112.5040", "abstract": "  Adiabatic approximations are a powerful tool for simplifying nonlinear quantum dynamics, and are applicable whenever a system exhibits a hierarchy of time scales. Current interest in small nonlinear quantum systems, such as few-mode Bose-Hubbard models, warrants further development of adiabatic methods in the particular context of these models. Here we extend our recent work on a simple four-mode Bose-Hubbard model with two distinct dynamical time scales, in which we showed that among the perturbations around excited stationary states of the system is a slow collective excitation that is not present in the Bogoliubov spectrum. We characterized this mode as a resonant energy exchange with its frequency shifted by nonlinear effects, and referred to it as a second Josephson oscillation, in analogy with the second sound mode of liquid helium II. We now generalize our previous theory beyond the mean field regime, and construct a general Bogoliubov free quasiparticle theory that explicitly respects the system's adiabatic invariant as well the exact conservation of particles. We compare this theory to the numerically exact quantum energy spectrum with up to forty particles, and find good agreement over a significant range of parameter space. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.5040v2.pdf"}
{"id": "1112.5274", "abstract": "  High-temperature expansions are presently the only viable approach to the numerical calculation of the higher susceptibilities for the spin and the scalar-field models on high-dimensional lattices. The critical amplitudes of these quantities enter into a sequence of universal amplitude-ratios which determine the critical equation of state. We have obtained a substantial extension through order 24, of the high-temperature expansions of the free energy (in presence of a magnetic field) for the Ising models with spin s >= 1/2 and for the lattice scalar field theory with quartic self-interaction, on the simple-cubic and the body-centered-cubic lattices in four, five and six spatial dimensions. A numerical analysis of the higher susceptibilities obtained from these expansions, yields results consistent with the widely accepted ideas, based on the renormalization group and the constructive approach to Euclidean quantum field theory, concerning the no-interaction (\"triviality\") property of the continuum (scaling) limit of spin-s Ising and lattice scalar-field models at and above the upper critical dimensionality. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.5274v1.pdf"}
{"id": "1112.5516", "abstract": "  In the present paper, we study finite-temperature phase structure of two-component hard-core bosons in a cubic optical lattice. The system that we study in the present paper is an effective model for the Bose-Hubbard model with strong on-site repulsions and is called bosonic t-J model. This model is a bosonic counterpart of the t-J model for the strongly-correlated electron systems like the high-temperature superconducting materials. We study the model by means of path-integral methods and Monte-Carlo simulations. We found that this system has a very rich phase structure including checkerboard-type \"insulating\" state, superfluid, phase-separated state, inhomogeneous cloudlet state, etc. We are also interested in the possible supersolid phase with both the checkerboard order and superfluidity and found that additional nearest-neighbor inter-species attractive force induces the supersolid state. In the supersolid state, paired superfluid appears in addition to the superfluid of single atom. This result gives important insight into mechanism of the high-temperature superconductivity of the cuprate. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.5516v3.pdf"}
{"id": "1112.6151", "abstract": "  We provide a new approach, along with extensions, to results in two important papers of Worsley, Siegmund and coworkers closely tied to the statistical analysis of fMRI (functional magnetic resonance imaging) brain data. These papers studied approximations for the exceedence probabilities of scale and rotation space random fields, the latter playing an important role in the statistical analysis of fMRI data. The techniques used there came either from the Euler characteristic heuristic or via tube formulae, and to a large extent were carefully attuned to the specific examples of the paper. This paper treats the same problem, but via calculations based on the so-called Gaussian kinematic formula. This allows for extensions of the Worsley-Siegmund results to a wide class of non-Gaussian cases. In addition, it allows one to obtain results for rotation space random fields in any dimension via reasonably straightforward Riemannian geometric calculations. Previously only the two-dimensional case could be covered, and then only via computer algebra. By adopting this more structured approach to this particular problem, a solution path for other, related problems becomes clearer. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.6151v2.pdf"}
{"id": "1201.1881", "abstract": "  Experimental data from the Relativistic Heavy Ion Collider (RHIC) suggests that the quark gluon plasma behaves almost like an ideal fluid. Due to its short lifetime, many QGP properties can only be inferred indirectly through a comparison of the final state measurements with transport model calculations. Among the current phenomena of interest are the interdependencies between two collective flow phenomena, elliptic and triangular flow. The former is mostly related to the initial geometry and collective expansion of the system whereas the latter is sensitive to the fluctuations of the initial state. For our investigation we use a hybrid transport model based on the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) transport approach using an ideal hydrodynamic expansion for the hot and dense stage. Using UrQMD initial conditions for an Au-Au collision, particles resulting from a collision are mapped into an energy density distribution that is evolved event-by-event with a hydrodynamic calculation. By averaging these distributions over different numbers of events, we have studied how the granularity/smoothness of the distribution affects the initial eccentricity, the initial triangularity, and the resulting flow components. The average elliptic flow in non central collisions is not sensitive to the granularity, while triangular flow is. The triangularity might thus provide a good measure of the amount of initial state fluctuations that is necessary to reproduce the experimental data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1201/1201.1881v1.pdf"}
{"id": "1201.5323", "abstract": "  We present a method for investigating the steady-state transport properties of one-dimensional correlated quantum systems. Using a procedure based on our analysis of finite-size effects in a related classical model (LC line) we show that stationary currents can be obtained from transient currents in finite systems driven out of equilibrium. The non-equilibrium dynamics of correlated quantum systems is calculated using the time-evolving block decimation method. To demonstrate our method we determine the full I-V characteristic of the spinless fermion model with nearest-neighbour hopping t_H and interaction V_H using two different setups to generate currents (turning on/off a potential bias). Our numerical results agree with exact results for non-interacting fermions (V_H=0). For interacting fermions we find that in the linear regime eV << 4t_H the current I is independent from the setup and our numerical data agree with the predictions of the Luttinger liquid theory combined with the Bethe Ansatz solution. For larger potentials V the steady-state current depends on the current-generating setup and as V increases we find a negative differential conductance with one setup while the currents saturate at finite values in the other one. Both effects are due to finite renormalized bandwidths. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1201/1201.5323v2.pdf"}
{"id": "1201.6368", "abstract": "  We obtain a new bound on the value of Peskin-Takeuchi S parameter in a wide class of bottom-up holographic models for technicolor. Namely, we show that weakly coupled holographic description in these models implies S>>0.2. Our bound is in conflict with the results of electroweak precision measurements, so it strongly disfavors the models we consider. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1201/1201.6368v2.pdf"}
{"id": "1202.0593", "abstract": "  The existence of asymmetries in the circular polarization (Stokes V) profiles emerging from the solar photosphere is known since the 1970s. These profiles require the presence of a velocity gradient along the line of sight, possibly associated with gradients of magnetic field strength, inclination and/or azimuth. We have focused our study on the Stokes V profiles showing extreme asymmetry in the from of only one lobe. Using Hinode spectropolarimetric measurements we have performed a statistical study of the properties of these profiles in the quiet sun. We show their spatial distribution, their main physical properties, how they are related with several physical observables and their behavior with respect to their position on the solar disk. The single lobed Stokes V profiles occupy roughly 2", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.0593v1.pdf"}
{"id": "1202.1731", "abstract": "  Observations of extreme-ultraviolet (EUV) emission from an X-class solar flare that occurred on 2011 February 15 at 01:44 UT are presented, obtained using the EUV Variability Experiment (EVE) onboard the Solar Dynamics Observatory. The complete EVE spectral range covers the free-bound continua of H I (Lyman continuum), He I, and He II, with recombination edges at 91.2, 50.4, and 22.8 nm, respectively. By fitting the wavelength ranges blue-ward of each recombination edge with an exponential function, lightcurves of each of the integrated continua were generated over the course of the flare, as well as emission from the free-free continuum (6.5-37 nm). The He II 30.4 nm and Lyman-alpha 121.6 nm lines, and soft X-ray (0.1-0.8 nm) emission from GOES are also included for comparison. Each free-bound continuum was found to have a rapid rise phase at the flare onset similar to that seen in the 25-50 keV lightcurves from RHESSI, suggesting that they were formed by recombination with free electrons in the chromosphere. However, the free-free emission exhibited a slower rise phase seen also in the soft X-ray emission from GOES, implying a predominantly coronal origin. By integrating over the entire flare the total energy emitted via each process was determined. We find that the flare energy in the EVE spectral range amounts to at most a few per cent of the total flare energy, but EVE gives us a first comprehensive look at these diagnostically important continuum components. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.1731v1.pdf"}
{"id": "1202.3920", "abstract": "  We have adopted the multistep shell model in the complex energy plane to study nuclear excitations occurring in the continuum part of the spectrum. In this method one proceeds by solving the shell model equations in a successive manner. That is, in each step one constructs the building blocks to be used in future steps. We applied this formalism to analyze the unbound nuclei ^12,13Li starting from the one-particle states in ^10Li and two-particle states in ^11Li. In the former case the excitations correspond to the motion of three particles partitioned as the product of a one-particle and two-particle systems. The ground state of ^12Li is thus calculated to be an antibound (virtual) state. In the four-particle system ^13Li the states can be constructed as the coupling of two correlated pairs. We found that there is no bound or antibound state in ^13Li. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.3920v1.pdf"}
{"id": "1202.4699", "abstract": "  We analyse the role played by shear in regulating star formation in the Galaxy on the scale of individual molecular clouds. The clouds are selected from the 13^CO J=1-0 line of the Galactic Ring Survey. For each cloud, we estimate the shear parameter which describes the ability of density perturbations to grow within the cloud. We find that for almost all molecular clouds considered, there is no evidence that shear is playing a significant role in opposing the effects of self-gravity. We also find that the shear parameter of the clouds does not depend on their position in the Galaxy. Furthermore, we find no correlations between the shear parameter of the clouds with several indicators of their star formation activity. No significant correlation is found between the shear parameter and the star formation efficiency of the clouds which is measured using the ratio of the massive young stellar objects luminosities, measured in the Red MSX survey, to the cloud mass. There are also no significant correlations between the shear parameter and the fraction of their mass that is found in denser clumps which is a proxy for their clump formation efficiency, nor with their level of fragmentation expressed in the number of clumps per unit mass. Our results strongly suggest that shear is playing only a minor role in affecting the rates and efficiencies at which molecular clouds convert their gas into dense cores and thereafter into stars. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.4699v4.pdf"}
{"id": "1202.6312", "abstract": "  In this work, we investigate the spatial distributions and the widths of the incompressible strips, i.e. the edgestates. The incompressible strips that correspond to ν=1,2 and 1/3 filling factors are examined in the presence of a strong perpendicular magnetic field. We present a microscopic picture of the fractional quantum Hall effect based interferometers, within a phenomenological model. We adopt Laughlin quasi-particle properties in our calculation scheme. In the fractional regime, the partially occupied lowest Landau level is assumed to form an energy gap due to strong correlations. Essentially by including this energy gap to our energy spectrum, we obtain the properties of the incompressible strips at ν=1/3. The interference conditions are investigated as a function of the gate voltage and steepness of the confinement potential, together with the strength of the applied magnetic field. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.6312v1.pdf"}
{"id": "1202.6354", "abstract": "  Many Web portals allow users to associate additional information with existing multimedia resources such as images, audio, and video. However, these portals are usually closed systems and user-generated annotations are almost always kept locked up and remain inaccessible to the Web of Data. We believe that an important step to take is the integration of multimedia annotations and the Linked Data principles. We present the current state of the Open Annotation Model, explain our design rationale, and describe how the model can represent user annotations on multimedia Web resources. Applying this model in Web portals and devices, which support user annotations, should allow clients to easily publish and consume, thus exchange annotations on multimedia Web resources via common Web standards. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.6354v1.pdf"}
{"id": "1203.0349", "abstract": "  A molecular gas system in three dimensions is numerically studied by the energy conserving molecular dynamics (MD). The autocorrelation functions for the velocity and the force are computed and the friction coefficient is estimated. From the comparison with the stochastic dynamics (SD) of a Brownian particle, it is shown that the force correlation function in MD is different from the delta-function force correlation in SD in short time scale. However, as the measurement time scale is increased further, the ensemble equivalence between the microcanonical MD and the canonical SD is restored. We also discuss the practical implication of the result. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.0349v1.pdf"}
{"id": "1203.0616", "abstract": "  We examine magnetorotationally driven supernovae as sources of r-process elements in the early Galaxy. On the basis of thermodynamic histories of tracer particles from a three-dimensional magnetohydrodynamical core-collapse supernova model with approximated neutrino transport, we perform nucleosynthesis calculations with and without considering the effects of neutrino absorption reactions on the electron fraction (Y_e) during post-processing. We find that the peak distribution of Y_e in the ejecta is shifted from ∼0.15 to ∼0.17 and broadened toward higher Y_e due to neutrino absorption. Nevertheless, in both cases the second and third peaks of the solar r-process element distribution can be well reproduced. The rare progenitor configuration that was used here, characterized by a high rotation rate and a large magnetic field necessary for the formation of bipolar jets, could naturally provide a site for the strong r-process in agreement with observations of the early galactic chemical evolution. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.0616v2.pdf"}
{"id": "1203.1025", "abstract": "  Modern nanotechnology allows producing, depending on application, various quantum nanostructures with the desired properties. These properties are strongly influenced by the confinement potential which can be modified, e.g., by electrical gating. In this paper we analyze a nanostructure composed of a quantum dot surrounded by a quantum ring. We show that depending on the details of the confining potential the electron wave functions can be located in different parts of the structure. Since the properties of such a nanostructure strongly depend on the distribution of the wave functions, varying the applied gate voltage one can easily control them. In particular, we illustrate the high controllability of the nanostructure by demonstrating how its coherent, optical, and conducting properties can be drastically changed by a small modification of the confining potential. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.1025v1.pdf"}
{"id": "1203.1633", "abstract": "  We analyze the computational complexity of solving the three \"temporal rift\" puzzles in the recent popular video game Final Fantasy XIII-2. We show that the Tile Trial puzzle is NP-hard and we provide an efficient algorithm for solving the Crystal Bonds puzzle. We also show that slight generalizations of the Crystal Bonds and Hands of Time puzzles are NP-hard. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.1633v1.pdf"}
{"id": "1203.1989", "abstract": "  We propose two schemes of field-effect transistor based on gapped armchair graphene nanoribbons connected to metal leads, by introducing sidearms or on-site gate voltages. We make use of the band gap to reach excellent switch-off character. By introducing one sidearm or on-site gate to the graphene nanoribbon, conduction peaks appear inside the gap regime. By further applying two sidearms or on-site gates, these peaks are broadened to conduction plateaus with a wide energy window, thanks to the resonance from the dual structure. The position of the conduction windows inside the gap can be fully controlled by the length of the sidearms or the on-site gate voltages, which allows \"on\" and \"off\" operations for a specific energy window inside the gap regime. The high robustness of both the switch-off character and the conduction windows is demonstrated and shows the feasibility of the proposed dual structures for real applications. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.1989v2.pdf"}
{"id": "1203.2268", "abstract": "  How important are friendships in determining success by individuals and teams in complex collaborative environments? By combining a novel data set containing the dynamics of millions of ad hoc teams from the popular multiplayer online first person shooter Halo: Reach with survey data on player demographics, play style, psychometrics and friendships derived from an anonymous online survey, we investigate the impact of friendship on collaborative and competitive performance. In addition to finding significant differences in player behavior across these variables, we find that friendships exert a strong influence, leading to both improved individual and team performance–even after controlling for the overall expertise of the team–and increased pro-social behaviors. Players also structure their in-game activities around social opportunities, and as a result hidden friendship ties can be accurately inferred directly from behavioral time series. Virtual environments that enable such friendship effects will thus likely see improved collaboration and competition. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.2268v2.pdf"}
{"id": "1203.2389", "abstract": "  Recently spin-orbit (SO) coupled superfluids in free space or harmonic traps have been extensively studied, motivated by the recent experimental realization of SO coupling for Bose-Einstein condensates (BEC). However, the rich physics of SO coupled BEC in optical lattices has been largely unexplored. In this paper, we show that in suitable parameter region the lowest Bloch state forms an isolated flat band in a one dimensional (1D) SO coupled optical lattice, which thus provides an experimentally feasible platform for exploring the recently celebrated topological flat band physics in lattice systems. We show that the flat band is preserved even with the mean field interaction in BEC. We investigate the superfluidity of the BEC in SO coupled lattices through dynamical and Landau stability analysis, and show that the BEC is stable on the whole flat band. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.2389v2.pdf"}
{"id": "1203.3058", "abstract": "  Inspired by the Games held in ancient Greece, modern Olympics represent the world's largest pageant of athletic skill and competitive spirit. Performances of athletes at the Olympic Games mirror, since 1896, human potentialities in sports, and thus provide an optimal source of information for studying the evolution of sport achievements and predicting the limits that athletes can reach. Unfortunately, the models introduced so far for the description of athlete performances at the Olympics are either sophisticated or unrealistic, and more importantly, do not provide a unified theory for sport performances. Here, we address this issue by showing that relative performance improvements of medal winners at the Olympics are normally distributed, implying that the evolution of performance values can be described in good approximation as an exponential approach to an a priori unknown limiting performance value. This law holds for all specialties in athletics-including running, jumping, and throwing-and swimming. We present a self-consistent method, based on normality hypothesis testing, able to predict limiting performance values in all specialties. We further quantify the most likely years in which athletes will breach challenging performance walls in running, jumping, throwing, and swimming events, as well as the probability that new world records will be established at the next edition of the Olympic Games. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.3058v2.pdf"}
{"id": "1203.3205", "abstract": "  The Pomeranchuk instability, in which an isotropic Fermi surface distorts and becomes anisotropic due to strong interactions, is a possible mechanism for the growing number of experimental systems which display transport properties that differ along the x and y axes. We show here that the gauge-gravity duality can be used to describe such an instability in fermionic systems. Our holographic model consists of fermions in a background which describes the causal propagation of a massive neutral spin-two field in an asymptotically AdS spacetime. The Fermi surfaces in the boundary theory distort spontaneously and become anisotropic once the neutral massive spin-two field develops a normalizable mode in the bulk. Analysis of the fermionic correlators reveals that the low-lying fermionic excitations are non-Fermi liquid-like both before and after the Fermi surface shape distortion. Further, the spectral weight along the Fermi surface is angularly dependent and can be made to vanish along certain directions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.3205v2.pdf"}
{"id": "1203.4060", "abstract": "  In this paper, we present recent progress in the development of hydrophobic silica aerogel as a Cherenkov radiator. In addition to the conventional method, the recently developed pin-drying method for producing high-refractive-index aerogels with high transparency was studied in detail. Optical qualities and large tile handling for crack-free aerogels were investigated. Sufficient photons were detected from high-performance aerogels in a beam test. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.4060v1.pdf"}
{"id": "1203.4506", "abstract": "  The availability of a large amount of observational data recently collected from magnetar outbursts is now calling for a complete theoretical study of outburst characteristics. In this letter (the first of a series dedicated to model magnetar outbursts), we tackle the long-standing open issue of whether or not short bursts and glitches are always connected to long-term radiative outbursts. We show that the recent detection of short bursts and glitches seemingly unconnected to outbursts is only misleading our understanding of these events. We show that, in the framework of the starquake model, neutrino emission processes in the magnetar crust limit the temperature, and therefore the luminosity. This natural limit to the maximum luminosity makes outbursts associated with bright persistent magnetars barely detectable. These events are simply seen as a small luminosity increase over the already bright quiescent state, followed by a fast return to quiescence. In particular, this is the case for 1RXS J1708-4009, 1E 1841-045, SGR 1806-20, and other bright persistent magnetars. On the other hand, a similar event (with the same energetics) in a fainter source will drive a more extreme luminosity variation and longer cooling time, as for sources such as XTE J1810-197, 1E 1547-5408 and SGR 1627-41. We conclude that the non-detection of large radiative outbursts in connection with glitches and bursts from bright persistent magnetars is not surprising per se, nor it needs of any revision on the glitches and burst mechanisms as explained by current theoretical models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.4506v1.pdf"}
{"id": "1204.0151", "abstract": "  Extreme value statistics (EVS) is applied to the distribution of galaxy luminosities in the Sloan Digital Sky Survey (SDSS). We analyze the DR8 Main Galaxy Sample (MGS), as well as the Luminous Red Galaxies (LRG). Maximal luminosities are sampled from batches consisting of elongated pencil beams in the radial direction of sight. For the MGS, results suggest a small and positive tail index ξ, effectively ruling out the possibility of having a finite maximum cutoff luminosity, and implying that the luminosity distribution function may decay as a power law at the high luminosity end. Assuming, however, ξ=0, a non-parametric comparison of the maximal luminosities with the Fisher-Tippett-Gumbel distribution (limit distribution for variables distributed by the Schechter fit) indicates a good agreement provided uncertainties arising both from the finite batch size and from the batch size distribution are accounted for. For a volume limited sample of LRGs, results show that they can be described as being the extremes of a luminosity distribution with an exponentially decaying tail, provided the uncertainties related to batch-size distribution are taken care of. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.0151v2.pdf"}
{"id": "1204.0855", "abstract": "  Due to lack of scientific understanding, some mechanisms may be missing in mathematical modeling of complex phenomena in science and engineering. These mathematical models thus contain some uncertainties such as uncertain parameters. One method to estimate these parameters is based on pathwise observations, i.e., quantifying model uncertainty in the space of sample paths for system evolution. Another method is devised here to estimate uncertain parameters, or unknown system functions, based on experimental observations of probability distributions for system evolution. This is called the quantification of model uncertainties in the space of probability measures. A few examples are presented to demonstrate this method, analytically or numerically. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.0855v1.pdf"}
{"id": "1204.1458", "abstract": "  Mobile phones have developed into complex platforms with large numbers of installed applications and a wide range of sensitive data. Application security policies limit the permissions of each installed application. As applications may interact, restricting single applications may create a false sense of security for the end users while data may still leave the mobile phone through other applications. Instead, the information flow needs to be policed for the composite system of applications in a transparent and usable manner. In this paper, we propose to employ static analysis based on the software architecture and focused data flow analysis to scalably detect information flows between components. Specifically, we aim to reveal transitivity of trust problems in multi-component mobile platforms. We demonstrate the feasibility of our approach with Android applications, although the generalization of the analysis to similar composition-based architectures, such as Service-oriented Architecture, can also be explored in the future. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.1458v1.pdf"}
{"id": "1204.1590", "abstract": "  Consider a particle diffusing in a confined volume which is divided into two equal regions. In one region the diffusion coefficient is twice the value of the diffusion coefficient in the other region. Will the particle spend equal proportions of time in the two regions in the long term? Statistical mechanics would suggest yes, since the number of accessible states in each region is presumably the same. However, another line of reasoning suggests that the particle should spend less time in the region with faster diffusion, since it will exit that region more quickly. We demonstrate with a simple microscopic model system that both predictions are consistent with the information given. Thus, specifying the diffusion rate as a function of position is not enough to characterize the behaviour of a system, even assuming the absence of external forces. We propose an alternative framework for modelling diffusive dynamics in which both the diffusion rate and equilibrium probability density for the position of the particle are specified by the modeller. We introduce a numerical method for simulating dynamics in our framework that samples from the equilibrium probability density exactly and is suitable for discontinuous diffusion coefficients. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.1590v3.pdf"}
{"id": "1204.1844", "abstract": "  Photoirradiation effects in correlated electrons coupled with localized spins are studied based on the extended double-exchange model. In particular, we examine melting of an antiferromagnetic (AFM) charge order insulating state by varying the light intensity. When intense light is irradiated, the AFM insulating characteristics are strengthened, rather than change into the ferromagnetic metallic characteristic, which are expected from the conventional double exchange interaction when carriers are introduced by weak light irradiation or chemical doping. This provides a new principle for optically manipulating magnetism. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.1844v2.pdf"}
{"id": "1204.2684", "abstract": "  In this work we derive the expressions of the neutrino mean free path(MFP) and emissivity with non Fermi liquid corrections up to next to leading order(NLO) in degenerate quark matter. The calculation has been performed both for the absorption and scattering processes. Subsequently the role of these NLO corrections on the cooling of the neutron star has been demonstrated. The cooling curve shows moderate enhancement compared to the leading order(LO) non-Fermi liquid result. Although the overall correction to the MFP and emissivity are larger compared to the free Fermi gas, the cooling behavior does not alter significantly. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.2684v2.pdf"}
{"id": "1204.2878", "abstract": "  We performed a first principles total energy investigation on the structural, electronic, and vibrational properties of adamantane molecules, functionalized with amine and ethanamine groups. We computed the vibrational signatures of amantadine and rimantadine isomers with the functional groups bonded to different carbon sites. By comparing our results with recent infrared and Raman spectroscopic data, we discuss the possible presence of different isomers in experimental samples. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.2878v1.pdf"}
{"id": "1204.5254", "abstract": "  The self-consistent Hartree-Fock-Bogoliubov problem in large boxes can be solved accurately in the coordinate space with the recently developed solvers HFB-AX (2D) and MADNESS-HFB (3D). This is essential for the description of superfluid Fermi systems with complicated topologies and significant spatial extend, such as fissioning nuclei, weakly-bound nuclei, nuclear matter in the neutron star rust, and ultracold Fermi atoms in elongated traps. The HFB-AX solver based on B-spline techniques uses a hybrid MPI and OpenMP programming model for parallel computation for distributed parallel computation, within a node multi-threaded LAPACK and BLAS libraries are used to further enable parallel calculations of large eigensystems. The MADNESS-HFB solver uses a novel multi-resolution analysis based adaptive pseudo-spectral techniques to enable fully parallel 3D calculations of very large systems. In this work we present benchmark results for HFB-AX and MADNESS-HFB on ultracold trapped fermions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.5254v1.pdf"}
{"id": "1204.6347", "abstract": "  We analyze the structure and stability of singular singly quantized vortices in a rotating spin-1 Bose-Einstein condensate. We show that the singular vortex can be energetically stable in both the ferromagnetic and polar phases despite the existence of a lower-energy nonsingular coreless vortex in the ferromagnetic phase. The spin-1 system exhibits an energetic hierarchy of length scales resulting from different interaction strengths and we find that the vortex cores deform to a larger size determined by the characteristic length scale of the spin-dependent interaction. We show that in the ferromagnetic phase the resulting stable core structure, despite apparent complexity, can be identified as a single polar core with axially symmetric density profile which is nonvanishing everywhere. In the polar phase, the energetically favored core deformation leads to a splitting of a singly quantized vortex into a pair of half-quantum vortices that preserves the topology of the vortex outside the extended core region, but breaks the axial symmetry of the core. The resulting half-quantum vortices exhibit nonvanishing ferromagnetic cores. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.6347v4.pdf"}
{"id": "1205.0055", "abstract": "  We present a direct link between the minimum variability time scales extracted through a wavelet decomposition and the rise times of the shortest pulses extracted via fits of 34 Fermi GBM GRB light curves comprised of 379 pulses. Pulses used in this study were fitted with log-normal functions whereas the wavelet technique used employs a multiresolution analysis that does not rely on identifying distinct pulses. By applying a corrective filter to published data fitted with pulses we demonstrate agreement between these two independent techniques and offer a method for distinguishing signal from noise. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.0055v4.pdf"}
{"id": "1205.0309", "abstract": "  For random graphs distributed according to a stochastic block model, we consider the inferential task of partioning vertices into blocks using spectral techniques. Spectral partioning using the normalized Laplacian and the adjacency matrix have both been shown to be consistent as the number of vertices tend to infinity. Importantly, both procedures require that the number of blocks and the rank of the communication probability matrix are known, even as the rest of the parameters may be unknown. In this article, we prove that the (suitably modified) adjacency-spectral partitioning procedure, requiring only an upper bound on the rank of the communication probability matrix, is consistent. Indeed, this result demonstrates a robustness to model mis-specification; an overestimate of the rank may impose a moderate performance penalty, but the procedure is still consistent. Furthermore, we extend this procedure to the setting where adjacencies may have multiple modalities and we allow for either directed or undirected graphs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.0309v2.pdf"}
{"id": "1205.0487", "abstract": "  This work discusses Hermitian and non-Hermitian formulations for the time evolution of quantum decay, that involve respectively, continuum wave functions and resonant states, to show that they lead to an identical description for a large class of well behaved potentials. Our approach is based on the analytical properties of the outgoing Green's function to the problem in the complex wave number plane. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.0487v1.pdf"}
{"id": "1205.0588", "abstract": "  In globular clusters, dynamical evolution produces luminous X-ray emitting binaries at a rate about 200 times greater than in the field. If globular clusters also produce SNe Ia at a high rate, it would account for much of the SN Ia events in early type galaxies and provide insight into their formation. Here we use archival HST images of nearby galaxies that have hosted SNe Ia to examine the rate at which globular clusters produce these events. The location of the SN Ia is registered on an HST image obtained before the event or after the supernova faded. Of the 36 nearby galaxies examined, 21 had sufficiently good data to search for globular cluster hosts. None of the 21 supernovae have a definite globular cluster counterpart, although there are some ambiguous cases. This places an upper limit to the enhancement rate of SN Ia production in globular clusters of about 42 at the 95", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.0588v1.pdf"}
{"id": "1205.0806", "abstract": "  The potential existence of a giant planet orbiting within a few AU of a stellar remnant has profound implications for both the survival and possible regeneration of planets during post-main sequence stellar evolution. This paper reports Hubble Space Telescope Fine Guidance Sensor and U.S. Naval Observatory relative astrometry of GD 66, a white dwarf thought to harbor a giant planet between 2 and 3 AU based on stellar pulsation arrival times. Combined with existing infrared data, the precision measurements here rule out all stellar-mass and brown dwarf companions, implying that only a planet remains plausible, if orbital motion is indeed the cause of the variations in pulsation timing. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.0806v1.pdf"}
{"id": "1205.2049", "abstract": "  We present an Advanced Camera for Surveys/ Solar Blind Channel far-ultraviolet (FUV) study of 2 gas in 12 weak T Tauri stars in nearby star-forming regions. The sample consists of sources which have no evidence of inner disk dust. Our new FUV spectra show that in addition to the dust, the gas is depleted from the inner disk. This sample is combined with a larger FUV sample of accretors and non-accretors with ages between 1 and 100 Myr, showing that as early as 1–3 Myr, systems both with and without gas are found. Possible mechanisms for depleting gas quickly include viscous evolution, planet formation and photoevaporation by stellar radiation fields. Since these mechanisms alone cannot account for the lack of gas at 1–3 Myr, it is likely that the initial conditions (e.g. initial disk mass or core angular momentum) contribute to the variety of disks observed at any age. We estimate the angular momentum of a cloud needed for most of the mass to fall very close to the central object and compare this to models of the expected distribution of angular momenta. Up to 20", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.2049v1.pdf"}
{"id": "1205.4522", "abstract": "  We discuss energy densities in the strong-interaction limit of density functional theory, deriving an exact expression within the definition (gauge) of the electrostatic potential of the exchange-correlation hole. Exact results for small atoms and small model quantum dots are compared with available approximations defined in the same gauge. The idea of a local interpolation along the adiabatic connection is discussed, comparing the energy densities of the Kohn-Sham, the physical, and the strong-interacting systems. We also use our results to analyze the local version of the Lieb-Oxford bound, widely used in the construction of approximate exchange-correlation functionals. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.4522v1.pdf"}
{"id": "1205.4843", "abstract": "  Finite differences, as a subclass of direct methods in the calculus of variations, consist in discretizing the objective functional using appropriate approximations for derivatives that appear in the problem. This article generalizes the same idea for fractional variational problems. We consider a minimization problem with a Lagrangian that depends on the left Riemann-Liouville fractional derivative. Using the Grunwald-Letnikov definition, we approximate the objective functional in an equispaced grid as a multi-variable function of the values of the unknown function on mesh points. The problem is then transformed to an ordinary static optimization problem. The solution to the latter problem gives an approximation to the original fractional problem on mesh points. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.4843v2.pdf"}
{"id": "1205.6249", "abstract": "  We study the problem of leader election among mobile agents operating in an arbitrary network modeled as an undirected graph. Nodes of the network are unlabeled and all agents are identical. Hence the only way to elect a leader among agents is by exploiting asymmetries in their initial positions in the graph. Agents do not know the graph or their positions in it, hence they must gain this knowledge by navigating in the graph and share it with other agents to accomplish leader election. This can be done using meetings of agents, which is difficult because of their asynchronous nature: an adversary has total control over the speed of agents. When can a leader be elected in this adversarial scenario and how to do it? We give a complete answer to this question by characterizing all initial configurations for which leader election is possible and by constructing an algorithm that accomplishes leader election for all configurations for which this can be done. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.6249v1.pdf"}
{"id": "1205.6408", "abstract": "  Recent observations of broken symmetries have partly demystified the pseudogap phase. Here we review evidence for long-range intra-unit-cell(IUC) nematic order and its unexpectedly strong coupling to the phase of the fluctuating stripes in the pseudogap states of underdoped Bi_2Sr_2CaCu_2O_8+δ. In particular, we focus on the analysis techniques that reveal this evidence in scanning tunneling spectroscopy data, the definition of the extracted IUC nematic order parameter, and a phenomenological theory of the coupling between the IUC nematic order and the previously reported coexisting fluctuating stripes. We also present a microscopic mechanism of IUC nematic order driven by on-site and near-neighbor repulsions. Finally we discuss open questions in the context of these results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.6408v1.pdf"}
{"id": "1206.0613", "abstract": "  This paper deals with the factor modeling for high-dimensional time series based on a dimension-reduction viewpoint. Under stationary settings, the inference is simple in the sense that both the number of factors and the factor loadings are estimated in terms of an eigenanalysis for a nonnegative definite matrix, and is therefore applicable when the dimension of time series is on the order of a few thousands. Asymptotic properties of the proposed method are investigated under two settings: (i) the sample size goes to infinity while the dimension of time series is fixed; and (ii) both the sample size and the dimension of time series go to infinity together. In particular, our estimators for zero-eigenvalues enjoy faster convergence (or slower divergence) rates, hence making the estimation for the number of factors easier. In particular, when the sample size and the dimension of time series go to infinity together, the estimators for the eigenvalues are no longer consistent. However, our estimator for the number of the factors, which is based on the ratios of the estimated eigenvalues, still works fine. Furthermore, this estimation shows the so-called \"blessing of dimensionality\" property in the sense that the performance of the estimation may improve when the dimension of time series increases. A two-step procedure is investigated when the factors are of different degrees of strength. Numerical illustration with both simulated and real data is also reported. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1206/1206.0613v1.pdf"}
{"id": "1206.1239", "abstract": "  We evaluate quantum corrections to conductivity in an electrically gated thin film of a three-dimensional (3D) topological insulator (TI). We derive approximate analytical expressions for the low-field magnetoresistance as a function of bulk doping and bulk-surface tunneling rate. Our results reveal parameter regimes for both weak localization and weak antilocalization, and include diffusive Weyl semimetals as a special case. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1206/1206.1239v3.pdf"}
{"id": "1206.4171", "abstract": "  Quenches in an ion chain can create coherent superpositions of motional states across the linear-zigzag structural transition. The procedure has been described in [Phys. Rev. A 84, 063821 (2011)] and makes use of spin-dependent forces, so that a coherent superposition of the electronic states of one ion evolves into an entangled state between the chain's internal and external degrees of freedom. The properties of the crystalline state so generated are theoretically studied by means of Ramsey interferometry on one ion of the chain. An analytical expression for the visibility of the interferometric measurement is obtained for a chain of arbitrary number of ions and as a function of the time elapsed after the quench. Sufficiently close to the linear-zigzag instability the visibility decays very fast, but exhibits revivals at the period of oscillation of the mode that drives the structural instability. These revivals have a periodicity that is independent of the crystal size, and they signal the creation of entanglement by the quantum quench. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1206/1206.4171v2.pdf"}
{"id": "1206.5146", "abstract": "  We study the structure, stability, and dynamics of dark solitary waves in parabolically trapped, collisionally inhomogeneous Bose-Einstein condensates (BECs) with spatially periodic variations of the scattering length. This collisional inhomogeneity yields a nonlinear lattice, which we tune from a small-amplitude, approximately sinusoidal structure to a periodic sequence of densely spaced spikes. We start by investigating time-independent inhomogeneities, and we subsequently examine the dynamical response when one starts with a collisionally homogeneous BEC and then switches on an inhomogeneity either adiabatically or nonadiabatically. Using Bogoliubov-de Gennes linearization as well as direct numerical simulations of the Gross-Pitaevskii equation, we observe dark solitary waves, which can become unstable through oscillatory or exponential instabilities. We find a critical wavelength of the nonlinear lattice that is comparable to the healing length. Near this value, the fundamental eigenmode responsible for the stability of the dark solitary wave changes its direction of movement as a function of the strength of the nonlinearity. When it increases, it collides with other eigenmodes, leading to oscillatory instabilities; when it decreases, it collides with the origin and becomes imaginary, illustrating that the instability mechanism is fundamentally different in wide-well versus narrow-well lattices. When starting from a collisionally homogeneous setup and switching on inhomogeneities, we find that dark solitary waves are preserved generically for aligned lattices. We briefly examine the time scales for the onset of solitary-wave oscillations in this scenario. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1206/1206.5146v2.pdf"}
{"id": "1206.6921", "abstract": "  How to distribute welfare in a society is a key issue in the subject of distributional justice, which is deeply involved with notions of fairness. Following a thought experiment by Dworkin, this work considers a society of individuals with different preferences on the welfare distribution and an official to mediate the coordination among them. Based on a simple assumption that an individual's welfare is proportional to how her preference is fulfilled by the actual distribution, we show that an egalitarian preference is a strict Nash equilibrium and can be favorable even in certain inhomogeneous situations. These suggest how communication can encourage and secure a notion of fairness. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1206/1206.6921v1.pdf"}
{"id": "1206.7057", "abstract": "  We experimentally verify the quantum non-Gaussian character of a conditionally generated noisy squeezed single-photon state with positive Wigner function. Employing an optimized witness based on probabilities of squeezed vacuum and squeezed single-photon states we prove that the state cannot be expressed as a mixture of Gaussian states. In our experiment, the non-Gaussian state is generated by conditional subtraction of a single photon from squeezed vacuum state. The state is probed with a homodyne detector and the witness is determined by averaging a suitable pattern function over the measured homodyne data. Our experimental results are in good agreement with a theoretical fit obtained from a simple yet realistic model of the experimental setup. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1206/1206.7057v1.pdf"}
{"id": "1207.0010", "abstract": "  We discuss the acceleration and escape of secondary particles, especially positrons produced by hadronic interactions in a supernova remnant (SNR) shock. During the shock acceleration, protons would interact with ambient gas and produce charged secondary particles, which would also be accelerated in a SNR and injected into the interstellar medium as cosmic-rays (CRs). Some previous studies showed that the resulting positron spectrum at the SNR shock is harder than the primary proton spectrum, and proposed that the positron excess observed by PAMELA can be explained with this process. We calculate the energy spectra of CR protons and secondary CR positrons running away from the SNR into the interstellar medium according to the phenomenological model of energy-dependent CR escape. We show that, on the contrary to the results presented previously, the observed spectra of secondary CR particles generated in SNRs would be softer than those of primary CR particles, which means that the rise in the positron fraction cannot be reproduced by this model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1207/1207.0010v3.pdf"}
{"id": "1207.0532", "abstract": "  We develop a Bayesian inference method that allows the efficient determination of several interesting parameters from complicated high-energy-density experiments performed on the National Ignition Facility (NIF). The model is based on an exploration of phase space using the hydrodynamic code HYDRA. A linear model is used to describe the effect of nuisance parameters on the analysis, allowing an analytic likelihood to be derived that can be determined from a small number of HYDRA runs and then used in existing advanced statistical analysis methods. This approach is applied to a recent experiment in order to determine the carbon opacity and X-ray drive; it is found that the inclusion of prior expert knowledge and fluctuations in capsule dimensions and chemical composition significantly improve the agreement between experiment and theoretical opacity calculations. A parameterisation of HYDRA results is used to test the application of both Markov chain Monte Carlo (MCMC) and genetic algorithm (GA) techniques to explore the posterior. These approaches have distinct advantages and we show that both can allow the efficient analysis of high energy density experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1207/1207.0532v1.pdf"}
{"id": "1207.0725", "abstract": "  The concept of Lyapunov exponent has long occupied a central place in the theory of Anderson localisation; its interest in this particular context is that it provides a reasonable measure of the localisation length. The Lyapunov exponent also features prominently in the theory of products of random matrices pioneered by Furstenberg. After a brief historical survey, we describe some recent work that exploits the close connections between these topics. We review the known solvable cases of disordered quantum mechanics involving random point scatterers and discuss a new solvable case. Finally, we point out some limitations of the Lyapunov exponent as a means of studying localisation properties. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1207/1207.0725v2.pdf"}
{"id": "1207.1948", "abstract": "  Resonant inelastic X-ray scattering (RIXS) spectra of model copper- and nickel-based transition metal oxides are measured over a wide range of energies near the M-edge (hν=60-80eV) to better understand the properties of resonant scattering involving shallow core levels. Standard multiplet RIXS calculations are found to deviate significantly from the observed spectra. However, by incorporating the self consistently calculated decay lifetime for each intermediate resonance state within a given resonance edge, we obtain dramatically improved agreement between data and theory. Our results suggest that these textured lifetime corrections can enable a quantitative correspondence between first principles predictions and RIXS data on model multiplet systems. This accurate model is also used to analyze resonant elastic scattering, which displays the elastic Fano effect and provides a rough upper bound for the core hole shake-up response time. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1207/1207.1948v2.pdf"}
{"id": "1207.2529", "abstract": "  We investigate the properties of a dark matter sector where supersymmetry is a good symmetry. In this context we find that the stability of the dark matter candidate is possible even when R-parity is broken in the visible sector. In order to illustrate the idea we investigate a simple scenario where the dark matter candidate is the lightest scalar field in the dark sector which annihilates mainly into two sfermions when these channels are available. We study the relic density constraints and the predictions for the dark matter detection experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1207/1207.2529v2.pdf"}
{"id": "1207.3199", "abstract": "  The role of incoherent tunneling in the diffusion of light atoms on surfaces is investigated. With this purpose, a Chudley-Elliot master equation constrained to nearest neighbors is considered within the Grabert-Weiss approach to quantum diffusion in periodic lattices. This model is applied to recent measurements of atomic H and D on Pt(111), rendering friction coefficients that are in the range of those available in the literature for other species of adsorbates. A simple extension of the model has also been considered to evaluate the relationship between coverage and tunneling, and therefore the feasibility of the approach. An increase of the tunneling rate has been observed as the surface coverage decreases. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1207/1207.3199v2.pdf"}
{"id": "1207.4815", "abstract": "  We discuss recent results on the cosmology of extended theories of gravity formulated in the Palatini approach, i.e., assuming that metric and connection are independent fields. In particular, we focus on the attempts to explain the cosmic speedup with f(R) theories and on models that avoid the big bang singularity. The field equations for gravity Lagrangians of the form f(g_μν,R^α_βμν) (including torsion) are explicitly derived and discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1207/1207.4815v1.pdf"}
{"id": "1207.4885", "abstract": "  High P_T measurements of hard hadrons or jets at RHIC and LHC appear contradictory and in some cases counter-intuitive, but upon closer investigation they represent a coherent picture of jet-medium interaction physics which can be established with systematic comparisons of models against a large body of data. This picture is consistent with a perturbative QCD mechanism and does not require exotic assumptions. This overview outlines how several key measurements each partially constrain shower-medium interaction physics and how from the sum of those the outlines of the mechanism of jet quenching can be deduced. Most current jet results from LHC can be naturally understood in this picture. A short summary of what can be established about the nature of parton-medium interaction with current data is given in the end. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1207/1207.4885v1.pdf"}
{"id": "1207.6153", "abstract": "  Most Gamma-ray bursts (GRBs) have erratic light curves, which demand that the GRB central engine launches an episodic outflow. Recent Fermi observations of some GRBs indicate a lack of the thermal photosphere component as predicted by the baryonic fireball model, which suggests a magnetic origin of GRBs. In view that powerful episodic jets have been observed along with continuous jets in other astrophysical black hole systems, here we propose an intrinsically episodic, magnetically-dominated jet model for GRB central engine. Accumulation and eruption of free magnetic energy in the corona of a differentially-rotating, turbulent accretion flow around a hyperaccreting black hole lead to ejections of episodic, magnetically dominated plasma blobs. These blobs are accelerated magnetically, collide with each other at large radii, trigger rapid magnetic reconnection and turbulence, efficient particle acceleration and radiation, and power the observed episodic prompt gamma-ray emission from GRBs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1207/1207.6153v1.pdf"}
{"id": "1207.6308", "abstract": "  Seesaw mechanism provides a natural explanation of light neutrino masses through suppression of heavy seesaw scale. In inverse seesaw models the seesaw scale can be much lower than that in the usual seesaw models. If terms inducing seesaw masses are further induced by loop corrections, the seesaw scale can be lowered to be in the range probed by experiments at the LHC without fine tuning. In this paper we construct models in which inverse seesaw neutrino masses are generated at two loop level. These models also naturally have dark matter candidates. Although the recent data from Xenon100 put stringent constraint on the models, they can be consistent with data on neutrino masses, mixing, dark matter relic density and direct detection. These models also have some interesting experimental signatures for collider and flavor physics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1207/1207.6308v3.pdf"}
{"id": "1208.2035", "abstract": "  We present the detection of pulsed gamma-ray emission from the Crab pulsar above 100 GeV with the VERITAS array of atmospheric Cherenkov telescopes. Gamma-ray emission at theses energies was not expected in pulsar models. The detection of pulsed emission above 100 GeV and the absence of an exponential cutoff makes it unlikely that curvature radiation is the primary production mechanism of gamma rays at these energies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1208/1208.2035v1.pdf"}
{"id": "1208.3049", "abstract": "  A GEANT4-based Monte-Carlo model is developed to study the performance of Endcap Time-Of-Flight (ETOF) at BESIII. It's found that the multiple scattering effects, mainly from the materials at the MDC endcap, can cause multi-hit on the ETOF's readout cell and significantly influence the timing property of ETOF. Multi-gap Resistive Plate Chamber (MRPC) with a smaller readout cell structure is more suitable for ETOF detector due to significantly reduced multi-hit rate, from 71.5", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1208/1208.3049v1.pdf"}
{"id": "1208.4577", "abstract": "  We introduce a new set of flow parameters to describe the time dependence of the equation of state and the speed of sound in single field cosmological models. A scale invariant power spectrum is produced if these flow parameters satisfy specific dynamical equations. We analyze the flow of these parameters and find four types of fixed points that encompass all known single field models. Moreover, near each fixed point we uncover new models where the scale invariance of the power spectrum relies on having simultaneously time varying speed of sound and equation of state. We describe several distinctive new models and discuss constraints from strong coupling and superluminality. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1208/1208.4577v1.pdf"}
{"id": "1209.2007", "abstract": "  What is the first prime? It seems that the number two should be the obvious answer, and today it is, but it was not always so. There were times when and mathematicians for whom the numbers one and three were acceptable answers. To find the first prime, we must also know what the first positive integer is. Surprisingly, with the definitions used at various times throughout history, one was often not the first positive integer (some started with two, and a few with three). In this article, we survey the history of the primality of one, from the ancient Greeks to modern times. We will discuss some of the reasons definitions changed, and provide several examples. We will also discuss the last significant mathematicians to list the number one as prime. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1209/1209.2007v2.pdf"}
{"id": "1209.2781", "abstract": "  We study the wealth distribution of the Bouchaud–Mézard (BM) model on complex networks. It has been known that this distribution depends on the topology of network by numerical simulations, however, no one have succeeded to explain it. Using \"adiabatic\" and \"independent\" assumptions along with the central-limit theorem, we derive equations that determine the probability distribution function. The results are compared to those of simulations for various networks. We find good agreement between our theory and the simulations, except the case of Watts–Strogatz networks with a low rewiring rate, due to the breakdown of independent assumption. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1209/1209.2781v2.pdf"}
{"id": "1209.3534", "abstract": "  We show that the Gamma distribution is not an adequate fit for the probability density function of drop diameters using the Kolmogorov-Smirnov goodness of fit test. We propose a different parametrization of drop size distributions, which not depending by any particular functional form, is based on the adoption of standardized central moments. The first three standardized central moments are sufficient to characterize the distribution of drop diamters at the ground. These parameters together with the drop count form a 4-tuple which fully describe the variability of the drop size distributions. The Cartesian product of this 4-tuple of parameters is the rainfall phase space. Using disdrometer data from 10 different locations we identify invariant, not depending on location, properties of the rainfall phenomenon. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1209/1209.3534v1.pdf"}
{"id": "1209.4989", "abstract": "  We study a recently proposed measure for the quantification of quantum non-Markovianity in the dynamics of open systems which is based on the exchange of information between the open system and its environment. This measure relates the degree of memory effects to certain optimal initial state pairs featuring a maximal flow of information from the environment back to the open system. We rigorously prove that the states of these optimal pairs must lie on the boundary of the space of physical states and that they must be orthogonal. This implies that quantum memory effects are maximal for states which are initially distinguishable with certainty, having a maximal information content. Moreover, we construct an explicit example which demonstrates that optimal quantum states need not be pure states. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1209/1209.4989v1.pdf"}
{"id": "1209.6138", "abstract": "  Determining the conditions under which a black hole can be produced is a long-standing and fundamental problem in general relativity. We use numerical simulations of colliding selfgravitating fluid objects to study the conditions of black-hole formation when the objects are boosted to ultrarelativistic speeds. Expanding on previous work, we show that the collision is characterized by a type-I critical behaviour, with a black hole being produced for masses above a critical value, M_c, and a partially bound object for masses below the critical one. More importantly, we show for the first time that the critical mass varies with the initial effective Lorentz factor <γ> following a simple scaling of the type M_c   K <γ>^-1.0, thus indicating that a black hole of infinitesimal mass is produced in the limit of a diverging Lorentz factor. Furthermore, because a scaling is present also in terms of the initial stellar compactness, we provide a condition for black-hole formation in the spirit of the hoop conjecture. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1209/1209.6138v2.pdf"}
{"id": "1210.0581", "abstract": "  Quantum decoherence and the transition to semiclassical behavior during inflation has been extensively considered in the literature. In this paper, we use a simple model to analyze the same process in ekpyrosis. Our result is that the quantum to classical transition would not happen during an ekpyrotic phase even for superhorizon modes, and therefore the fluctuations cannot be interpreted as classical. This implies the prediction of scale-free power spectrum in ekpyrotic/cyclic universe model requires more inspection. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.0581v2.pdf"}
{"id": "1210.2151", "abstract": "  We examine the dynamics of two-dimensional colloidal systems using numerical simulations of a system with a drive applied to a thin region in the middle of the sample to produce a local shear. For a monodisperse colloidal assembly, we find a well defined decoupling transition separating a regime of elastic motion from a plastic phase where the particles in the driven region break away or decouple from the particles in the bulk, producing a shear band. For a bidisperse assembly, we find that the onset of a bulk disordering transition coincides with the broadening of the shear band. We identify several distinct dynamical regimes that are correlated with features in the velocity-force curves. As a function of bidispersity, the decoupling force shows a nonmonotonic behavior associated with features in the noise fluctuations, power spectra, and bulk velocity profiles. When pinning is added in the bulk, we find that the shear band regions can become more localized, causing a decoupling of the driven particles from the bulk particles. For a system with thermal noise and no pinning, the shear band region becomes more extended and the average velocity of the driven particles drops at the thermal disordering transition of the bulk system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.2151v1.pdf"}
{"id": "1210.3284", "abstract": "  We consider matter fields conformally coupled to a background metric and dilaton and describe in detail a quantization procedure and related renormalization group flow that preserve Weyl invariance. Even though the resulting effective action is Weyl-invariant, the trace anomaly is still present, with all its physical consequences. We discuss first the case of free matter and then extend the result to interacting matter. We also consider the case when the metric and dilaton are dynamical and gravitons enter in the loops. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.3284v1.pdf"}
{"id": "1210.3657", "abstract": "  One of the challenges of collider physics is to unambiguously associate detector based objects with the corresponding elementary physics objects. A particular example is the association of calorimeter-based objects such as \"jets\", identified with a standard (IR-safe) jet algorithm, with the underlying physics objects, which may be QCD-jets (arising from a scattered parton), electrons, photons and, as discussed here, photon-jets (a group of collinear photons). This separation is especially interesting in the context of Higgs searches, where the signal includes both di-photon (in the Standard Model) and di-photon-jet decays (in a variety of Beyond the Standard Model scenarios), while QCD provides an ever-present background. Here we describe the implementation of techniques from the rapidly evolving area of jet-substructure studies to not only enhance the more familiar photon-QCD separation, but also separately distinguish photon-jets, i.e., separate usual jets into three categories: single photons, photon-jets and QCD. The efficacy of these techniques for separation is illustrated through studies of simulated data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.3657v2.pdf"}
{"id": "1210.5211", "abstract": "  There is no wide accepted theory for ELM (Edge Localized Mode) yet. Some fusion people feel that we may never get a final theory for ELM and H-mode, since which are too complicated (also related to the unsolved turbulence problem) and with at least three time scales. The only way out is using models. (This is analogous to that we believe quantum mechanics can explain chemistry and biology, but no one can calculate DNA structure from Schrodinger equation directly.) This manuscript gives some possible mathematical approaches to it. I should declare that these are just math toys for me yet. They may inspire to good understandings of ELM and H-mode, may not. Useful or useless, I don't know. One need not take too much care of it. Just for fun and enjoying different interesting ideas. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.5211v1.pdf"}
{"id": "1210.5304", "abstract": "  Monte-Carlo (MC) methods, based on random updates and the trial-and-error principle, are well suited to retrieve particle size distributions from small-angle scattering patterns of dilute solutions of scatterers. The size sensitivity of size determination methods in relation to the range of scattering vectors covered by the data is discussed. Improvements are presented to existing MC methods in which the particle shape is assumed to be known. A discussion of the problems with the ambiguous convergence criteria of the MC methods are given and a convergence criterion is proposed, which also allows the determination of uncertainties on the determined size distributions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.5304v1.pdf"}
{"id": "1210.5996", "abstract": "  Anisotropy effects for spin avalanches in crystals of nanomagnets are studied theoretically with the external magnetic field applied at an arbitrary angle to the easy axis. Starting with the Hamiltonian for a single nanomagnet in the crystal, the two essential quantities characterizing spin avalanches are calculated: the activation energy and the Zeeman energy. The calculation is performed numerically for the wide range of angles and analytical formulas are derived within the limit of small angles. The anisotropic properties of a single nanomagnet lead to anisotropic behavior of the magnetic deflagration speed. Modifications of the magnetic deflagration speed are investigated for different angles between the external magnetic field and the easy axis of the crystals. Anisotropic properties of magnetic detonation are also studied, which concern, first of all, temperature behind the leading shock and the characteristic time of spin switching in the detonation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.5996v2.pdf"}
{"id": "1210.6002", "abstract": "  The rotating radio transients are sporadic pulsars which are difficult to detect through periodicity searches. By using a single-pulse search method, we can discover these sources, measure their periods, and determine timing solutions. Here we introduce our results on six RRATs based on Parkes and Green Bank Telescope(GBT) observations, along with a comparison of the spin-down properties of RRATs and normal pulsars. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.6002v2.pdf"}
{"id": "1210.6099", "abstract": "  The STAR experiment at RHIC has a unique capability of measuring identified hadrons over a wide range of pseudorapidity (η), transverse momentum (p_T), and azimuthal angle (ϕ) acceptance. The data collected (√(s_NN) = 7.7, 11.5, and 39 GeV) in its beam energy scan (BES) program provide a chance to investigate the final hadronic state freeze-out conditions of ultrarelativistic Au+Au collisions. The particle ratios are used to compare to a statistical model calculation using both grand canonical and strangeness canonical ensembles to extract the chemical freeze-out parameters. The p_T distributions are fitted to calculations using a blast-wave model to obtain the kinetic freeze-out parameters. We discuss the centrality dependence of the extracted chemical and kinetic freeze-out parameters at these lower energies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.6099v1.pdf"}
{"id": "1211.0191", "abstract": "  The paper evaluates the error performance of three random finite set based multi-object trackers in the context of pedestrian video tracking. The evaluation is carried out using a publicly available video dataset of 4500 frames (town centre street) for which the ground truth is available. The input to all pedestrian tracking algorithms is an identical set of head and body detections, obtained using the Histogram of Oriented Gradients (HOG) detector. The tracking error is measured using the recently proposed OSPA metric for tracks, adopted as the only known mathematically rigorous metric for measuring the distance between two sets of tracks. A comparative analysis is presented under various conditions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.0191v1.pdf"}
{"id": "1211.1558", "abstract": "  In this work, we study the generalized second law of thermodynamics (GSL) at the apparent horizon of an evolving Lorentzian wormhole. We obtain the expressions of thermal variables at the apparent horizon. Choosing the two well-known entropy functions i.e. power-law and logarithmic, we obtain the expressions of GSL. We have analyzed the GSL using a power-law form of scale factor a(t)=a_0t^n and the special form of shape function b(r)=b_0/r. It is shown that GSL is valid in the evolving wormhole spacetime for both choices of entropies if the power-law exponent is small, but for large values of n, the GSL is satisfied at initial stage and after certain stage of the evolution of the wormhole, it violates. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.1558v1.pdf"}
{"id": "1211.1774", "abstract": "  Topological insulators have become one of the most active research areas in condensed matter physics. This article reviews progress on the topic of electronic correlations effects in the two-dimensional case, with a focus on systems with intrinsic spin-orbit coupling and numerical results. Topics addressed include an introduction to the noninteracting case, an overview of theoretical models, correlated topological band insulators, interaction-driven phase transitions, topological Mott insulators and fractional topological states, correlation effects on helical edge states, and topological invariants of interacting systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.1774v3.pdf"}
{"id": "1211.2709", "abstract": "  In this paper, we present own point of view how the unexpected fluctuations of the long-term real interest rate can be explained. We describe a macroeconomic environment by the modification of the fundamental macroeconomic equilibrium model called the IS-LM model. Last but not least, we suggest a possible cooperation between the fiscal and monetary policy to reduce these fluctuations. Our modelling is demonstrated on an illustrative example. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.2709v2.pdf"}
{"id": "1211.6803", "abstract": "  According to the core accretion theory, circumbinary embryos can form only beyond a critical semimajor axis (CSMA). However, due to the relatively high density of solid materials in the inner disk, significant amount of small planetesimals must exist in the inner zone when embryos were forming outside this CSMA. So embryos migration induced by the planetesimal swarm is possible after the gas disk depletion. Through numerical simulations, we found (i) the scattering-driven inward migration of embryos is robust, planets can form in the habitable zone if we adopt a mass distribution of MMSN-like disk; (ii) the total mass of the planetesimals in the inner region and continuous embryo-embryo scattering are two key factors that cause significant embryo migrations; (iii) the scattering-driven migration of embryos is a natural water-deliver mechanism. We propose that planet detections should focus on the close binary with its habitable zone near CSMA. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.6803v1.pdf"}
{"id": "1211.7096", "abstract": "  The Sunyaev-Zeldovich (SZ) effect is a promising tool to study physical properties of the hot X-ray emitting intracluster medium (ICM) in galaxy clusters. To date, most SZ observations have been interpreted in combination with X-ray follow-up measurements in order to determine the ICM temperature and estimate the cluster mass. Future high-resolution, multifrequency SZ observations promise to enable detailed studies of the ICM structures, by measuring the ICM temperature through the temperature-dependent relativistic corrections. In this work we develop a non-parametric method to derive three-dimensional physical quantities, including temperature, pressure, total mass, and peculiar velocities, of galaxy clusters from SZ observations alone. We test the performance of this method using hydrodynamical simulations of galaxy clusters, in order to assess systematic uncertainties in the reconstructed physical parameters. In particular, we analyze mock Cerro Chajnantor Atacama Telescope (CCAT) SZ observations, taking into account various sources of systematic uncertainties associated with instrumental effects and astrophysical foregrounds. We show that our method enables accurate reconstruction of the three-dimensional ICM profiles, while retaining full information about the gas distribution. We discuss the application of this technique for ongoing and future multifrequency SZ observations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.7096v2.pdf"}
{"id": "1212.1536", "abstract": "  We consider the hierarchic tree Random Energy Model with continuous branching and calculate the moments of the corresponding partition function. We establish the multifractal properties of those moments. We derive formulas for the normal distribution of random variables, as well as for the general case. We compare our results for the moments of partition function with corresponding results of logarithmic 1-d REM and conjecture a specific power-law tail for the partition function distribution in the high-temperature phase. Our results establish a connection between reaction-diffusion equations and multi-scaling. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1212/1212.1536v1.pdf"}
{"id": "1212.1985", "abstract": "  We discuss processes in galactic cosmic ray (GCR) acceleration sites - supernova remnants, compact associations of young massive stars, and superbubbles. Mechanisms of efficient conversion of the mechanical power of the outflows driven by supernova shocks and fast stellar winds of young stars into magnetic fields and relativistic particles are discussed. The high efficiency of particle acceleration in the sources implies the importance of nonlinear feedback effects in a symbiotic relationship where the magnetic turbulence required to accelerate the CRs is created by the accelerated CRs themselves. Non-thermal emission produced by relativistic particles (both those confined in and those that escape from the cosmic accelerators) can be used to constrain the basic physical models of the GCR sources. High resolution X-ray synchrotron imaging, combined with GeV-TeV gamma ray spectra, is a powerful tool to probe the maximum energies of accelerated particles. Future MeV regime spectroscopy will provide unique information on the composition of accelerated particles. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1212/1212.1985v1.pdf"}
{"id": "1212.4520", "abstract": "  Hidden sectors with light extra U(1) gauge bosons, so-called hidden photons, recently received much interest as natural feature of beyond standard model scenarios like string theory and SUSY and because of their possible connection to dark matter. This paper presents limits on hidden photons from past electron beam dump experiments including two new limits from experiments at KEK and Orsay. Additionally, various hidden sector models containing both a hidden photon and a dark matter candidate are discussed with respect to their viability and potential signatures in direct detection. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1212/1212.4520v1.pdf"}
{"id": "1212.4778", "abstract": "  We analyze the rate at which quantum information encoded in zero-energy Majorana modes is lost in the presence of perturbations. We show that information can survive for times that scale exponentially with the size of the chain both in the presence of quenching and time-dependent quadratic dephasing perturbations, even when the latter have spectral components above the system's energy gap. The origin of the robust storage, namely the fact that a sudden quench affects in the same way both parity sectors of the original spectrum, is discussed, together with the memory performance at finite temperatures and in the presence of particle exchange with a bath. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1212/1212.4778v2.pdf"}
{"id": "1212.5214", "abstract": "  Bell's theorem is a fundamental result in quantum mechanics: it discriminates between quantum mechanics and all theories where probabilities in measurement results arise from the ignorance of pre-existing local properties. We give an extremely simple proof of Bell's inequality: a single figure suffices. This simplicity may be useful in the unending debate of what exactly the Bell inequality means, since the hypothesis at the basis of the proof become extremely transparent. It is also a useful didactic tool, as the Bell inequality can be explained in a single intuitive lecture. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1212/1212.5214v2.pdf"}
{"id": "1301.1777", "abstract": "  We have examined the singlet excitons in two representatives of acene-type (tetracene and pentacene) and phenacene-type (chrysene and picene) molecular crystals, respectively, using electron energy-loss spectroscopy at low temperatures. We show that the excitation spectra of the two hydrocarbon families significantly differ. Moreover, close inspection of the data indicates that there is an increasing importance of charge-transfer excitons at lowest excitation energy with increasing length of the molecules. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.1777v1.pdf"}
{"id": "1301.3131", "abstract": "  In the widely adopted LambdaCDM scenario for galaxy formation, dwarf galaxies are the building blocks of larger galaxies. Since they formed at relatively early epochs when the background density was relatively high, they are expected to retain their integrity as satellite galaxies when they merge to form larger entities. Although many dwarf spheroidal galaxies (dSphs) are found in the galactic halo around the Milky Way, their phase space density (or velocity dispersion) appears to be significantly smaller than that expected for satellite dwarf galaxies in the LambdaCDM scenario. In order to account for this discrepancy, we consider the possibility that they may have lost a significant fraction of their baryonic matter content during the first infall at the Hubble expansion turnaround. Such mass loss arises naturally due to the feedback by relatively massive stars which formed in their centers briefly before the maximum contraction. Through a series of N-body simulations, we show that the timely loss of a significant fraction of the dSphs initial baryonic matter content can have profound effects on their asymptotic half-mass radius, velocity dispersion, phase-space density, and the mass fraction between residual baryonic and dark matter. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.3131v1.pdf"}
{"id": "1301.3279", "abstract": "  We study the properties of the nuclear rotational excitations with hypothetical tetrahedral symmetry by employing the microscopic mean-field and residual-interaction Hamiltonians with angular-momentum and parity projection method; we focus on the deformed nuclei with tetrahedral doubly-closed shell configurations. We find that for pure tetrahedral deformation the obtained excitation patterns satisfy the characteristic features predicted by group-representation theory applied to the tetrahedral symmetry group. We find that a gradual transition from the approximately linear to the characteristic rigid-rotor, parabolic energy-vs.-spin dependence occurs as a function of the tetrahedral deformation parameter. The form of this transition is compared with the similar well-known transition in the case of quadrupole deformation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.3279v3.pdf"}
{"id": "1301.3910", "abstract": "  The formation and evolution of protoplanetary discs remains a challenge from both a theoretical and numerical standpoint. In this work we first perform a series of tests of our new hybrid algorithm presented in Glaschke, Amaro-Seoane and Spurzem 2011 (henceforth Paper I) that combines the advantages of high accuracy of direct-summation N-body methods with a statistical description for the planetesimal disc based on Fokker-Planck techniques. We then address the formation of planets, with a focus on the formation of protoplanets out of planetesimals. We find that the evolution of the system is driven by encounters as well as direct collisions and requires a careful modelling of the evolution of the velocity dispersion and the size distribution over a large range of sizes. The simulations show no termination of the protoplanetary accretion due to gap formation, since the distribution of the planetesimals is only subjected to small fluctuations. We also show that these features are weakly correlated with the positions of the protoplanets. The exploration of different impact strengths indicates that fragmentation mainly controls the overall mass loss, which is less pronounced during the early runaway growth. We prove that the fragmentation in combination with the effective removal of collisional fragments by gas drag sets an universal upper limit of the protoplanetary mass as a function of the distance to the host star, which we refer to as the mill condition. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.3910v1.pdf"}
{"id": "1301.6053", "abstract": "  We examine a Bloch Oscillating Transistor pair as a differential stage for cryogenic low-noise measurements. Using two oppositely biased, nearly symmetric Bloch Oscillating Transistors, we measured the sum and difference signals in the current gain and transconductance modes while changing the common mode signal, either voltage or current. From the common mode rejection ratio we find values ∼ 20 dB even under non-optimal conditions. We also characterize the noise properties and obtain excellent noise performance for measurements having source impedances in the MΩ range. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.6053v2.pdf"}
{"id": "1301.7092", "abstract": "  This paper summarizes the three-day international workshop \"Radio Stars and Their Lives in the Galaxy\", held at the Massachusetts Institute of Technology Haystack Observatory on 2012 October 3-5. The workshop was organized to provide a forum for the presentation and discussion of advances in stellar and solar astrophysics recently (or soon to be) enabled by the latest generation of state-of-the-art observational facilities operating from meter to submillimeter wavelengths. The meeting brought together both observers and theorists to discuss how radio wavelength observations are providing new and unique insights into the workings of stars and their role in the Galactic ecosystem. Topics covered included radio emission from hot and cool stars (from the pre- to post-main-sequence), the Sun as a radio star, circumstellar chemistry, planetary nebulae, white dwarf binaries and novae, supernova progenitors, and radio stars as probes of the Galaxy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.7092v2.pdf"}
{"id": "1302.0253", "abstract": "  The muscle contraction, operation of ATP synthase, maintaining the shape of a cell are believed to be secured by motor proteins, which can be modelled using the Brownian ratchet mechanism. We consider the randomly flashing ratchet model of a Brownian motor, where the particles can be in two states, only one of which is sensitive the applied spatially periodic potential (the mathematical setting is a pair of weakly coupled reaction-diffusion and Fokker-Planck equations). We prove that this mechanism indeed generates unidirectional transport by showing that the amount of mass in the wells of the potential decreases/increases from left to right. The direction of transport is unambiguously determined by the location of each minimum of the potential with respect to the so-called diffusive mean of its adjacent maxima. The transport can be generated not only by an asymmetric potential, but also by a symmetric potential and asymmetric transition rates, and as a consequence of the general result we derive explicit conditions when the latter happens. When the transitions are localized on narrow active sites in the protein conformation space, we find a more explicit characterization of the bulk transport direction, and infer that some common preconditions of the motor effect are redundant. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1302/1302.0253v2.pdf"}
{"id": "1302.0510", "abstract": "  In the currently popular orientation-based unified scheme, a radio galaxy appears as a quasar when its principal radio-axis happens to be oriented within a certain cone opening angle around the observer's line of sight. Due to geometrical projection, the observed sizes of quasars should therefore appear smaller than those of radio galaxies. We show that this simple, unambiguous prediction of the unified scheme is not borne out by the actually observed angular sizes of radio galaxies and quasars. Except in the original 3CR sample, based on which the unified scheme was proposed, in other much larger samples no statistically significant difference is apparent in the size distributions of radio galaxies and quasars. The population of low-excitation radio galaxies with apparently no hidden quasars inside, which might explain the observed excess number of radio galaxies at low redshifts, cannot still account for the absence of any foreshortening of the sizes of quasars at large redshifts. On the other hand from infrared and X-ray studies there is evidence of hidden quasar within a dusty torus in many RGs, at z>0.5. It seems difficult how to reconcile this with the absence of foreshortening of quasar sizes at even these redshifts, and perhaps one has to allow that the major radio axis may not have anything to do with the optical axis of the torus. Otherwise to resolve the dichotomy of radio galaxies and quasars, a scheme quite different from the present might be required. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1302/1302.0510v1.pdf"}
{"id": "1302.0796", "abstract": "  A new experimental evaluation of the quenching factor for nuclear recoils in NaI[Tl] is described. Systematics affecting previous measurements are addressed by careful characterization of the emission spectrum of the neutron source, use of a small scintillator coupled to an ultra-bialkali high quantum efficiency photomultiplier, and evaluation of non-linearities in the electron recoil response via Compton scattering. A trend towards a rapidly diminishing quenching factor with decreasing sodium recoil energy is revealed. Additionally, no evidence for crystal lattice channeling of low-energy recoiling ions is found in a scintillator of known crystallographic orientation. A discussion on how these findings affect dark matter searches employing NaI[Tl] (e.g., DAMA/LIBRA) is offered. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1302/1302.0796v2.pdf"}
{"id": "1302.3376", "abstract": "  Recent studies have shown that the observed main-sequence turn-off (MSTO) in colour-magnitude diagrams of intermediate age (1-2 Gyr) clusters in the LMC are broader than would be nominally expected for a simple stellar population. This has led to the suggestion that such clusters may host multiple stellar populations, with age spreads of 100-500 Myr. However, at intermediate ages, spreads of this magnitude are difficult to discern and alternative explanations have been put forward (e.g., stellar rotation, interacting binaries). A prediction of the age-spread scenario is that younger clusters in the LMC, with similar masses and radii, should also show significant age spreads. In younger clusters (i.e., 40-300 Myr) such large age spreads should be readily apparent. We present an analysis of the colour-magnitude diagrams of two massive young clusters in the LMC (NGC 1856 and NGC 1866) and show that neither have such large age spreads, in fact, both are consistent with a single burst of star-formation (sigma(age) < 35 Myr). This leads us to conclude that either the intermediate age clusters in the LMC are somehow special or that the broadened MSTOs are not due to an age spread within the clusters. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1302/1302.3376v1.pdf"}
{"id": "1302.4701", "abstract": "  In this letter, following a cross-layer design concept, we propose a novel subcarrier grouping technique for Orthogonal Frequency and Code Division Multiplexing (OFCDM) multiuser systems. We adopt a two dimensional (2D) spreading, so as to achieve both frequency- and time-domain channel gain. Furthermore, we enable a receiver-centric approach, where the receiver rather than a potential sender controls the admission decision of the communication establishment. We study the robustness of the proposed scheme in terms of the Bit-Error-Rate (BER) and the outage probability. The derived results indicate that the proposed scheme outperforms the classical OFCDM approach. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1302/1302.4701v1.pdf"}
{"id": "1302.5163", "abstract": "  According to General Relativity, as distinct from Newtonian gravity, motion under gravity is treated by a theory that deals, initially, only with test particles. At the same time, satellite measurements deal with extended bodies. We discuss the correspondence between geodesic motion in General Relativity and the motion of an extended body by means of the Ehlers-Geroch theorem, and in the context of the recently launched LAser RElativity Satellite (LARES). Being possibly the highest mean density orbiting body in the Solar system, this satellite provides the best realization of a test particle ever reached experimentally and provides a unique possibility for testing the predictions of General Relativity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1302/1302.5163v1.pdf"}
{"id": "1303.2667", "abstract": "  We created artificial color-magnitude diagrams of Monte Carlo dynamical models of globular clusters, and then used observational methods to determine the number of blue stragglers in those clusters. We compared these blue stragglers to various cluster properties, mimicking work that has been done for blue stragglers in Milky Way globular clusters to determine the dominant formation mechanism(s) of this unusual stellar population. We find that a mass-based prescription for selecting blue stragglers will choose approximately twice as many blue stragglers than a selection criterion that was developed for observations of real clusters. However, the two numbers of blue stragglers are well-correlated, so either selection criterion can be used to characterize the blue straggler population of a cluster. We confirm previous results that the simplified prescription for the evolution of a collision or merger product in the BSE code overestimates their lifetimes. We show that our model blue stragglers follow similar trends with cluster properties (core mass, binary fraction, total mass, collision rate) as the true Milky Way blue stragglers, as long as we restrict ourselves to model clusters with an initial binary fraction higher than 5", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1303/1303.2667v2.pdf"}
{"id": "1303.3298", "abstract": "  In the present work we examine both the linear and nonlinear properties of two related PT-symmetric systems of the discrete nonlinear Schrodinger (dNLS) type.   First, we examine the parameter range for which the finite PT-dNLS chains have real eigenvalues and PT-symmetric linear eigenstates. We develop a systematic way of analyzing the nonlinear stationary states with the implicit function theorem at an analogue of the anti-continuum limit for the dNLS equation.   Secondly, we consider the case when a finite PT-dNLS chain is embedded as a defect in the infinite dNLS lattice. We show that the stability intervals of the infinite PT-dNLS lattice are wider than in the case of a finite PT-dNLS chain. We also prove existence of localized stationary states (discrete solitons) in the analogue of the anti-continuum limit for the dNLS equation.   Numerical computations illustrate the existence of nonlinear stationary states, as well as the stability and saddle-center bifurcations of discrete solitons. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1303/1303.3298v1.pdf"}
{"id": "1303.4311", "abstract": "  The ability to describe production of light fragments (LF) is important for many applications, such as cosmic-ray-induced single event upsets (SEUs), radiation protection, and cancer therapy with proton and heavy-ion beams. The Cascade-Exciton Model (CEM) and the Los Alamos version of the Quark-Gluon String Model (LAQGSM) event generators in the LANL transport code MCNP6, describe quite well the spectra of fragments with sizes up to 4He across a broad range of target masses and incident energies (up to   5 GeV for CEM and up to   1 TeV/A for LAQGSM). However, they do not predict the high-energy tails of LF spectra heavier than 4He well. Most LF with energies above several tens of MeV are emitted during the precompound stage of a reaction. The current versions of our event generators do not account for precompound emission of LF larger than 4He. The aim of our work is to generalize the precompound model to include such processes, leading to increased predictive power of LF production. Extending the model in this way provides preliminary results that have much better agreement with experimental data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1303/1303.4311v1.pdf"}
{"id": "1303.4608", "abstract": "  It is demonstrated that in many thermodynamic textbooks the equivalence of the different ensembles is achieved in the thermodynamic limit. In this present work we remark the inequivalence of microcannonical and canonical ensembles in a finite ultracold system at low energies. We calculate the microcanonical momentum distribution function (MDF) in a system of identical fermions (bosons). We find that, the microcanonical MDF deviates from the canonical one, which is the Fermi-Dirac (Bose-Einstein) function, in a finite system at low energies where the single-particle density of states and its inverse are finite. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1303/1303.4608v2.pdf"}
{"id": "1303.4619", "abstract": "  Cross-sectional area and volume become difficult to define as material dimensions approach the atomic scale. This limits the transferability of macroscopic concepts such as Young's modulus. We propose a new volume definition where the enclosed nanosheet or nanotube average electron density matches that of the parent layered bulk material. We calculate the Young's moduli for various nanosheets (including graphene, BN and MoS2) and nanotubes. Further implications of this new volume definition such as a Fermi level dependent Young's modulus and out-of-plane Poisson's ratio are shown. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1303/1303.4619v1.pdf"}
{"id": "1303.6356", "abstract": "  We present a method for implementing a weak optical Kerr interaction (single-mode Kerr Hamiltonian) in a measurement-based fashion using the common set of universal elementary interactions for continuous-variable quantum computation. Our scheme is a conceptually distinct alternative to the use of naturally occurring, weak Kerr nonlinearities or specially designed nonlinear media. Instead, we propose to exploit suitable offline prepared quartic ancilla states together with beam splitters, squeezers, and homodyne detectors. For perfect ancilla states and ideal operations, our decompositions for obtaining the measurement-based Kerr Hamiltonian lead to a realization with near-unit fidelity. Nonetheless, even by using only approximate ancilla states in the form of superposition states of up to four photons, high fidelities are still attainable. Our scheme requires four elementary operations and its deterministic implementation corresponds to about ten ancilla- based gate teleportations. We test our measurement-based Kerr interaction against an ideal Kerr Hamiltonian by applying them both to weak coherent states and single-photon superposition states. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1303/1303.6356v1.pdf"}
{"id": "1304.0477", "abstract": "  We present an investigation of potential signatures of the formation of multiple stellar populations in recently formed extragalactic star clusters. All of the Galactic globular clusters for which good samples of individual stellar abundances are available show evidence for multiple populations. This appears to require that multiple episodes of star formation and light element enrichment are the norm in the history of a globular cluster. We show that there are detectable observational signatures of multiple formation events in the unresolved spectra of massive, young extragalactic star clusters. We present the results of a pilot program to search for one of the cleanest signatures that we identify - the combined presence of emission lines from a very recently formed population and absorption lines from a somewhat older population. A possible example of such a system is identified in the Antennae galaxies. This source's spectrum shows evidence of two stellar populations with ages of 8 Myr and 80 Myr. Further investigation shows that these populations are in fact physically separated, but only by a projected distance of 59 pc. We show that the clusters are consistent with being bound and discuss the possibility that their coalescence could result in a single globular cluster hosting multiple stellar populations. While not the prototypical system proposed by most theories of the formation of multiple populations in clusters, the detection of this system in a small sample is both encouraging and interesting. Our investigation suggests that expanded surveys of massive young star clusters should detect more clusters with such signatures. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.0477v1.pdf"}
{"id": "1304.1807", "abstract": "  We study the thermalization process in classical Yang-Mills (CYM) field theory starting from noisy glasma-like initial conditions by investigating the initial-value sensitivity of trajectories. Kunihiro et al. linked entropy generation to the Kolmogorov-Sinai entropy, which gives the entropy production rate in classical chaotic systems, calculated numerically for CYM fields starting from purely random initial field configurations. In contrast, we here study glasma-like initial conditions. For small random fluctuations we obtain qualitatively similar results while no entropy increase is observed when such fluctuations are absent. We analyze the intermediate time Lyapunov spectrum for several time windows and calculate the Kolmogorov-Sinai entropy. We find a large number of positive Lyapunov exponents at the early stages of time evolution. Also for later times their number is a sizeable fraction of the total number of degrees of freedom. The spectrum of positive Lyapunov exponents at first changes rapidly, but then stabilizes, indicating that the dynamics of the gauge fields approaches a steady state. Thus we conclude that also for glasma-like initial conditions a significant amount of entropy is produced by classical gluon field dynamics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.1807v1.pdf"}
{"id": "1304.1873", "abstract": "  Formalism to calculate the hydrodynamic fluctuations by applying the Onsager theory to the relativistic Navier-Stokes equation is already known. In this work, we calculate hydrodynamic-fluctuations within the framework of the second order hydrodynamics of Müller, Israel and Stewart and its generalization to the third order. We have also calculated the fluctuations for several other causal hydrodynamical equations. We show that the form for the Onsager-coefficients and form of the correlation-functions remains same as those obtained by the relativistic Navier-Stokes equation and it does not depend on any specific model of hydrodynamics. Further we numerically investigate evolution of the correlation function using the one dimensional boost-invariant (Bjorken) flow. We compare the correlation functions obtained using the causal hydrodynamics with the correlation-function for the relativistic Navier-Stokes equation. We find that the qualitative behavior of the correlation-functions remain same for all the models of the causal hydrodynamics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.1873v3.pdf"}
{"id": "1304.3339", "abstract": "  We have obtained and analyzed long-slit spectral data for the lenticular galaxy IC 719. In this gas-rich S0 galaxy, its large-scale gaseous disk counterrotates the global stellar disk. Moreover in the IC 719 disk we have detected a secondary stellar component corotating the ionized gas. By using emission-line intensity ratios, we have proved the gas excitation by young stars and so are claiming current star formation, most intense in a ring-like zone at the radius of 10\" (1.4 kpc). The oxygen abundance of the gas in the starforming ring is about half of the solar abundance. Since the stellar disk remains dynamically cool, we conclude that smooth prolonged accretion of the external gas from a neighboring galaxy provides urrent building of the thin large-scale stellar disk. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.3339v1.pdf"}
{"id": "1304.5358", "abstract": "  The Munich 2D-ACAR spectrometer at the Maier-Leibnitz accelerator laboratory in Garching has recently become operational. In the present implementation a 2D-ACAR spectrometer is set up, with a baseline of 16.5m, a conventional 22Na positron source and two Anger-type gamma-cameras. The positrons are guided onto the sample by a magnetic field generated by a normal conducting electromagnet. The sample can be either cooled by a standard closed-cycle-cryostat to low temperatures or heated by a resistive filament to temperatures up to 500K. We present the key features of this new 2D-ACAR spectrometer and, in addition, discuss first measurements on the pure metal system Cr. The 2D-ACAR measurements have been performed on Cr at different temperatures: at 5K and at room temperature in the anti-ferromagnetic phase and at 318K slightly above the paramagnetic phase transition. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.5358v1.pdf"}
{"id": "1304.5361", "abstract": "  Because of the temporal incoherence of sunlight, solar cells efficiency should depend on the degree of coherence of the incident light. However, numerical computation methods, which are used to optimize these devices, fundamentally consider fully coherent light. Hereafter, we show that the incoherent efficiency of solar cells can be easily analytically calculated. The incoherent efficiency is simply derived from the coherent one thanks to a convolution product with a function characterizing the incoherent light. Our approach is neither heuristic nor empiric but is deduced from first-principle, i.e. Maxwell's equations. Usually, in order to reproduce the incoherent behavior, statistical methods requiring a high number of numerical simulations are used. With our method, such approaches are not required. Our results are compared with those from previous works and good agreement is found. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.5361v2.pdf"}
{"id": "1304.5589", "abstract": "  We theoretically investigate the experimental observable of the ballistic collective group delay (CGD) of all the particles on the Fermi surface in graphene. First, we reveal that, lateral Goos-Hänchen (GH) shifts along barrier interfaces contribute an inherent component in the individual group delay (IGD). Then, by linking the complete IGD to spin precession through a dwell time, we suggest that, the CGD and its GH component can be electrostatically measured by a conductance difference in a spin-precession experiment under weak magnetic fields. Such an approach is feasible for almost arbitrary Fermi energy. We also indicate that, it is a generally nonzero self-interference delay that relates the IGD and dwell time in graphene. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.5589v1.pdf"}
{"id": "1305.1834", "abstract": "  It is commonly known that stable bright solitons in periodic potentials, which represent gratings in photonics/plasmonics, or optical lattices in quantum gases, exist either in the spectral semi-infinite gap (SIG) or in finite bandgaps. Using numerical methods, we demonstrate that, under the action of the cubic self-focusing nonlinearity, defects in the form of \"holes\" in two-dimensional (2D) lattices support continuous families of 2D solitons embedded into the first two Bloch bands of the respective linear spectrum, where solitons normally do not exist. The two families of the embedded defect solitons (EDSs) are found to be continuously linked by the branch of gap defect solitons (GDSs) populating the first finite bandgap. Further, the EDS branch traversing the first band links the GDS family with the branch of regular defect-supported solitons populating the SIG. Thus, we construct a continuous chain of regular, embedded, and gap-mode solitons (\"superfamily\") threading the entire bandgap structure considered here. The EDSs are stable in the first Bloch band, and partly stable in the second. They exist with the norm exceeding a minimum value, hence they do not originate from linear defect modes. Further, we demonstrate that double, triple and quadruple lattice defects support stable dipole-mode solitons and vortices. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.1834v1.pdf"}
{"id": "1305.2194", "abstract": "  We consider the challenging problem of obtaining an analytic understanding of realistic astrophysical dynamics in the presence of a Vainshtein screened fifth force arising from infrared modifications of General Relativity. In particular, we attempt to solve – within the most general flat spacetime galileon model – the scalar force law between well separated bodies located well within the Vainshtein radius of the Sun. To this end, we derive the exact static Green's function of the galileon wave equation linearized about the background field generated by the Sun, for the minimal cubic and maximally quartic galileon theories, and then introduce a method to compute the general leading order force law perturbatively away from these limits. We also show that the same nonlinearities which produce the Vainshtein screening effect present obstacles to an analytic calculation of the galileon forces between closely bound systems within the solar system, such as that of the Earth and Moon. Within the test mass approximation, we deduce that a large enough quartic galileon interaction would suppress the effect on planetary perihelion precession below the level detectable by even the next-generation experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.2194v2.pdf"}
{"id": "1305.2251", "abstract": "  We propose a novel method for image representation in quantum computers, which uses the two-dimensional (2-D) quantum states to locate each pixel in an image through row-location and column-location vectors for identifying each pixel location. The quantum state of an image is the linear superposition of the tensor product of the m-qubits row-location vector and the n-qubits column-location vector of each pixel. It enables the natural quantum representation of rectangular images that other methods lack. The amplitude/intensity of each pixel is incorporated into the coefficient values of the pixel's quantum state, without using any qubits. Due to the fact that linear superposition, tensor product and qubits form the fundamental basis of quantum computing, the proposed method presents the machine level representation of images on quantum computers. Unlike other methods, this method is a pure quantum representation without any classical components. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.2251v4.pdf"}
{"id": "1305.3026", "abstract": "  We present the experimental realization of a laser system for ground to satellite optical Doppler ranging at the atmospheric turbulence limit. Such a system needs to display good frequency stability (a few parts in 10^-14) whilst allowing large and well controlled frequency sweeps of +/- 12 GHz at rates exceeding 100 MHz/s. Furthermore it needs to be sufficiently compact and robust for transportation to different astronomical observation sites where it is to be interfaced with satellite ranging telescopes. We demonstrate that our system fulfills those requirements and should therefore allow operation of ground to low Earth orbit satellite coherent optical links limited only by atmospheric turbulence. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.3026v1.pdf"}
{"id": "1305.4520", "abstract": "  We consider the use of cyclic weak measurements to improve the sensitivity of weak-value amplification precision measurement schemes. Previous weak-value experiments have used only a small fraction of events, while discarding the rest through the process of \"post-selection\". We extend this idea by considering recycling of events which are typically unused in a weak measurement. Here we treat a sequence of polarized laser pulses effectively trapped inside an interferometer using a Pockels cell and polarization optics. In principle, all photons can be post-selected, which will improve the measurement sensitivity. We first provide a qualitative argument for the expected improvements from recycling photons, followed by the exact result for the recycling of collimated beam pulses, and numerical calculations for diverging beams. We show that beam degradation effects can be mitigated via profile flipping or Zeno reshaping. The main advantage of such a recycling scheme is an effective power increase, while maintaining an amplified deflection. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.4520v1.pdf"}
{"id": "1305.6762", "abstract": "  Hedging in the presence of transaction costs leads to complex optimization problems. These problems typically lack closed-form solutions, and their implementation relies on numerical methods that provide hedging strategies for specific parameter values. In this paper we use a genetic programming algorithm to derive explicit formulas for near-optimal hedging strategies under nonlinear transaction costs. The strategies are valid over a large range of parameter values and require no information about the structure of the optimal hedging strategy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.6762v1.pdf"}
{"id": "1305.7351", "abstract": "  In this work, we propose a detailed computational framework for modelling the envelope of the swept volume, that is the boundary of the volume obtained by sweeping an input solid along a trajectory of rigid motions. Our framework is adapted to the well-established industry-standard brep format to enable its implementation in modern CAD systems. This is achieved via a \"local analysis\", which covers parametrization and singularities, as well as a \"global theory\" which tackles face-boundaries, self-intersections and trim curves. Central to the local analysis is the \"funnel\" which serves as a natural parameter space for the basic surfaces constituting the sweep. The trimming problem is reduced to the problem of surface-surface intersections of these basic surfaces. Based on the complexity of these intersections, we introduce a novel classification of sweeps as either decomposable or non-decomposable. Further, we construct an invariant function θ on the funnel which efficiently separates decomposable and non-decomposable sweeps. Through a geometric theorem we also show intimate connections between θ, local curvatures and the inverse trajectory used in earlier works as an approach towards trimming. In contrast to the inverse trajectory approach, θ is robust and is the key to a complete structural understanding, and an efficient computation of both, the singular locus and the trim curves, which are central to a stable implementation. Several illustrative outputs of a pilot implementation are included. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.7351v1.pdf"}
{"id": "1306.0749", "abstract": "  Conformations of a single-component bottle-brush polymer with a fully flexible backbone under poor solvent conditions are studied by molecular-dynamics simulations, using a coarse-grained bead-spring model with side chains of up to N=40 effective monomers. By variation of the solvent quality and the grafting density σ with which side chains are grafted onto the flexible backbone, we study for backbone lengths of up to N_b=100 the crossover from the brush/coil regime to the dense collapsed state. At lower temperatures, where collapsed chains with a constant monomer density are observed, the choice of the above parameters does not play any role and it is the total number of monomers that defines the dimensions of the chains. Furthermore, bottle-brush polymers with longer side chains possess higher spherical symmetry compared to chains with lower side-chain lengths in contrast to what one may intuitively expect, as the stretching of the side chains is less important than the increase of their length. At higher temperatures, always below the Theta (Θ) temperature, coil-like configurations, similar to a single polymer chain, or brush-like configurations, similar to a homogeneous cylindrical bottle-brush polymer with a rigid backbone, are observed, depending on the choice of the particular parameters N and σ. In the crossover regime between the collapsed state (globule) and the coil/brush regime the acylindricity increases, whereas for temperatures outside of this range, bottle-brush polymers maintain a highly cylindrical symmetry in all configurational states. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.0749v1.pdf"}
{"id": "1306.1088", "abstract": "  A new experimental equipment allowing to study the sputtering induced by ion beam irradiation is presented. The sputtered particles are collected on a catcher which is analyzed in situ by Auger electron spectroscopy without breaking the ultra high vacuum (less than 10-9mbar), avoiding thus any problem linked to possible contamination. This method allows to measure the angular distribution of sputtering yield. Thanks to this new setup it is now possible to study the sputtering of many elements especially light elements such as carbon based materials. Preliminary results are presented in the case of highly oriented pyrolytic graphite and tungsten irradiated by an Ar+ beam at respectively 2.8 keV and 7 keV. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.1088v1.pdf"}
{"id": "1306.2700", "abstract": "  We propose a hierarchical interference mitigation scheme for massive MIMO cellular networks. The MIMO precoder at each base station (BS) is partitioned into an inner precoder and an outer precoder. The inner precoder controls the intra-cell interference and is adaptive to local channel state information (CSI) at each BS (CSIT). The outer precoder controls the inter-cell interference and is adaptive to channel statistics. Such hierarchical precoding structure reduces the number of pilot symbols required for CSI estimation in massive MIMO downlink and is robust to the backhaul latency. We study joint optimization of the outer precoders, the user selection, and the power allocation to maximize a general concave utility which has no closed-form expression. We first apply random matrix theory to obtain an approximated problem with closed-form objective. We show that the solution of the approximated problem is asymptotically optimal with respect to the original problem as the number of antennas per BS grows large. Then using the hidden convexity of the problem, we propose an iterative algorithm to find the optimal solution for the approximated problem. We also obtain a low complexity algorithm with provable convergence. Simulations show that the proposed design has significant gain over various state-of-the-art baselines. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.2700v3.pdf"}
{"id": "1306.3558", "abstract": "  The outlying property detection problem is the problem of discovering the properties distinguishing a given object, known in advance to be an outlier in a database, from the other database objects. In this paper, we analyze the problem within a context where numerical attributes are taken into account, which represents a relevant case left open in the literature. We introduce a measure to quantify the degree the outlierness of an object, which is associated with the relative likelihood of the value, compared to the to the relative likelihood of other objects in the database. As a major contribution, we present an efficient algorithm to compute the outlierness relative to significant subsets of the data. The latter subsets are characterized in a \"rule-based\" fashion, and hence the basis for the underlying explanation of the outlierness. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.3558v1.pdf"}
{"id": "1306.4884", "abstract": "  This paper presents a new partial two-player game, called the cannibal animal game, which is a variant of Tic-Tac-Toe. The game is played on the infinite grid, where in each round a player chooses and occupies free cells. The first player Alice can occupy a cell in each turn and wins if she occupies a set of cells, the union of a subset of which is a translated, reflected and/or rotated copy of a previously agreed upon polyomino P (called an animal). The objective of the second player Bob is to prevent Alice from creating her animal by occupying in each round a translated, reflected and/or rotated copy of P. An animal is a cannibal if Bob has a winning strategy, and a non-cannibal otherwise. This paper presents some new tools, such as the bounding strategy and the punching lemma, to classify animals into cannibals or non-cannibals. We also show that the pairing strategy works for this problem. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.4884v1.pdf"}
{"id": "1306.6200", "abstract": "  A finite-energy sum-rule is presented that allows for the use of combinations of both positive- and inverse-moment integration kernels. The freedom afforded from being able to employ this large class of integration kernels in our sum-rule is then exploited to obtain the values of the charm and bottom masses with minimum total uncertainty. We obtain as our final results m_c(3 GeV)=986(13) MeV and m_b(10 GeV)=3617(25) MeV, which are amongst the most precise values of these parameters obtained by any method. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.6200v1.pdf"}
{"id": "1306.6571", "abstract": "  We derive a time-dependent density functional theory appropriate for calculating the near-edge X-ray absorption spectrum in molecules and condensed matter. The basic assumption is to increase the space of many-body wave functions from one Slater determinant to two. The equations of motion derived from Dirac's variational principle provide an exact solution for the linear response when the interaction Hamiltonian has only a core-electron field. The equations can be solved numerically nearly as easily as the ordinary real-time time-dependent Kohn-Sham equations. We carry out the solution under conditions that permit comparison with the expected power-law behavior. Our extracted power-law exponents are similar to those derived by Nozieres and DeDominicis, but are not in quantitative agreement. We argue that our calculational method can be readily generalized to density functionals that take into account the more general electron-electron interactions that are needed for treating dynamic effects such as plasmon excitations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.6571v1.pdf"}
{"id": "1306.6766", "abstract": "  We use the latest Planck constraints, and in particular constraints on the derived parameters (Hubble constant and age of the Universe) for the local universe and compare them with local measurements of the same quantities. We propose a way to quantify whether cosmological parameters constraints from two different experiments are in tension or not. Our statistic, T, is an evidence ratio and therefore can be interpreted with the widely used Jeffrey's scale. We find that in the framework of the LCDM model, the Planck inferred two dimensional, joint, posterior distribution for the Hubble constant and age of the Universe is in \"strong\" tension with the local measurements; the odds being   1:50. We explore several possibilities for explaining this tension and examine the consequences both in terms of unknown errors and deviations from the LCDM model. In some one-parameter LCDM model extensions, tension is reduced whereas in other extensions, tension is instead increased. In particular, small total neutrino masses are favored and a total neutrino mass above 0.15 eV makes the tension \"highly significant\" (odds   1:150). A consequence of accepting this interpretation of the tension is that the degenerate neutrino hierarchy is highly disfavoured by cosmological data and the direct hierarchy is slightly favored over the inverse. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.6766v1.pdf"}
{"id": "1307.0418", "abstract": "  We study the flow structure in the jittering-jets explosion model of core-collapse supernovae (CCSNe) using 2.5D hydrodynamical simulations and find that some basic requirements for explosion are met by the flow. In the jittering-jets model jets are launched by intermittent accretion disk around the newly born neutron star and in stochastic directions. They deposit their kinetic energy inside the collapsing core and induce explosion by ejecting the outer core. The accretion and launching of jets is operated by a feedback mechanism: when the jets manage to eject the core, the accretion stops. We find that even when the jets' directions are varied around the symmetry axis they inflate hot bubbles that manage to expel gas in all directions. We also find that although most of the ambient core gas is ejected outward, sufficient mass to power the jets is accreted (0.1Mo), mainly from the equatorial plane direction. This is compatible with the jittering jets explosion mechanism being a feedback mechanism. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.0418v2.pdf"}
{"id": "1307.1261", "abstract": "  We have calculated the exchange-energy contribution to the total energy of quasi-two-dimensional hole systems realized by a hard-wall quantum-well confinement of valence-band states in typical semiconductors. The magnitude of the exchange energy turns out to be suppressed from the value expected for analogous conduction-band systems whenever the mixing between heavy-hole and light-hole components is strong. Our results are obtained using a very general formalism for calculating the exchange energy of many-particle systems where single-particle states are spinors. We have applied this formalism to obtain analytical results for spin-3/2 hole systems in limiting cases. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.1261v2.pdf"}
{"id": "1307.1575", "abstract": "  We consider non-Abrikosov vortex solutions in liquid metallic hydrogen (LMH) in the framework of two-component Ginzburg-Landau model. We have shown that there are three types of non-Abrikosov vortices depending on chosen boundary conditions at the core of vortices, namely, Neumann (N)-type, Dirichlet (D)-type and Gross-Pitaevskii (GP)-type vortices. The Neumann-type vortex has a non-vanishing condensation at the core, that is different from the ordinary vortex, and the magnetic flux could be reversed as well in LMH. Furthermore, we have obtained a new type of a neutral vortex which has no magnetic field. The presence of such a vortex is related to metallic superfluid state suggested by Babaev. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.1575v1.pdf"}
{"id": "1307.1911", "abstract": "  We performed VLBA observations of the Broad Absorption Line Quasar FIRST J155633.8+351758, \"the first radio loud BALQSO\". Our observations at 15.3 GHz partially resolved a secondary component at positional angle (PA) ≈ 35^∘. We combine this determination of the radio jet projection on the sky plane, with the constraint that the jet is viewed within 14.3^∘ of the line of sight (as implied by the high variability brightness temperature) and with the position angle (PA) of the optical/UV continuum polarization in order to study the quasar geometry. Within the context of the standard model, the data indicates a \"dusty torus\" (scattering surface) with a symmetry axis tilted relative to the accretion disk normal and a polar broad absorption line outflow aligned with the accretion disk normal. We compare this geometry to that indicated by the higher resolution radio data, brightness temperature and optical/UV continuum polarization PA of a similar high optical polarization BALQSO, Mrk 231. A qualitatively similar geometry is found in these two polar BALQSOs; the continuum polarization is determined primarily by the tilt of the dusty torus. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.1911v1.pdf"}
{"id": "1307.2866", "abstract": "  Cobalt-related impurity centers in diamond have been studied using first principles calculations. We computed the symmetry, formation and transition energies, and hyperfine parameters of cobalt impurities in isolated configurations and in complexes involving vacancies and nitrogen atoms. We found that the Co impurity in a divacant site is energetically favorable and segregates nitrogen atoms in its neighborhood. Our results were discussed in the context of the recently observed Co-related electrically active centers in synthetic diamond. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.2866v1.pdf"}
{"id": "1307.5131", "abstract": "  The idea that a quantum magnet could act like a liquid crystal, breaking spin-rotation symmetry without breaking time-reversal symmetry, holds an abiding fascination. However, the very fact that spin nematic states do not break time-reversal symmetry renders them \"invisible\" to the most common probes of magnetism - they do not exhibit magnetic Bragg peaks, a static splitting of lines in NMR spectra, or oscillations in muSR. Nonetheless, as a consequence of breaking spin-rotation symmetry, spin-nematic states do possess a characteristic spectrum of dispersing excitations which could be observed in experiment. With this in mind, we develop a symmetry-based description of long-wavelength excitations in a spin-nematic state, based on an SU(3) generalisation of the quantum non-linear sigma model. We use this field theory to make explicit predictions for inelastic neutron scattering, and argue that the wave-like excitations it predicts could be used to identify the symmetries broken by the otherwise unseen spin-nematic order. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.5131v2.pdf"}
{"id": "1307.5936", "abstract": "  We observed the 2012-2013 superoutburst of the newly identified transient SSS J122221.7-311523 and found that this object showed successive two superoutbursts. Superhumps grew in amplitude during the second superoutburst and showed a characteristic pattern of period change reflecting the growth of the superhump. Assuming that the periods of superhumps during the growing stage [0.07721(1) d] and post-superoutburst stage [0.07673(3) d], represent the dynamical precession rates at the radius of the 3:1 resonance and the radius immediately after the superoutburst, respectively, we found that this object has a very small mass ratio q=M2/M1 < 0.05. The possible orbital period from quiescent data suggests q=0.045, one of the smallest among hydrogen-rich cataclysmic variables. The long orbital period and low q make this object a perfect candidate for a period bouncer. We suggest that the peculiar pattern of double superoutburst is a result of a low q and may be characteristic to period bouncers. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.5936v1.pdf"}
{"id": "1307.6917", "abstract": "  The paper investigates uniform convergence of wavelet expansions of Gaussian random processes. The convergence is obtained under simple general conditions on processes and wavelets which can be easily verified. Applications of the developed technique are shown for several classes of stochastic processes. In particular, the main theorem is adjusted to the fractional Brownian motion case. New results on the rate of convergence of the wavelet expansions in the space C([0,T]) are also presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.6917v1.pdf"}
{"id": "1308.0865", "abstract": "  The total spectral weight S of the emergent low-energy quasipaticles in high-temperature superconductors is explored by x-ray absorption spectroscopy. In order to examine the applicability of the Hubbard model, regimes that cover from zero doping to overdoping are investigated. In contrast to mean field theory, we found that S deviates from linear dependence on the doping level p. The slope of S versus p changes continuously throughout the whole doping range with no sign of saturation up to p = 0.23. Therefore, the picture of Zhang-Rice singlet remains intact within the most prominent doping regimes of HTSC's. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.0865v1.pdf"}
{"id": "1308.2306", "abstract": "  Recently, two-dimensional nanostructures consisting of alternating graphene and boron nitride (BN) domains have been synthesized. These systems possess interesting electronic and mechanical properties, with potential applications in electronics and optical devices. Here, we perform a first-principles investigation of models of BN-C hybrid monolayers and nanoribbons deposited on the Cu(111) surface, a substrate used for their growth in said experiments. For the sake of comparison, we also consider BN and BC2N nanostructures. We show that BN and BC2N monolayers bind weakly to Cu(111), whereas monolayers with alternating domains interact strongly with the substrate at the B-C interface, due to the presence of localized interface states. This binding leads to a deformation of the monolayers and sizable n-doping. Nanoribbons exhibit a similar behaviour. Furthermore, they also interact significantly with the substrate at the edge, even in the case of passivated edges. These findings suggest a route to tune the band gap and doping level of BN-C hybrid models based on the interplay between nanostructuring and substrate-induced effects. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.2306v1.pdf"}
{"id": "1308.2967", "abstract": "  The study of young stars no longer surrounded by disks can greatly add to our understanding of how protoplanetary disks evolve and planets form. We have used VLT/FLAMES optical spectroscopy to confirm the youth and membership of 19 new young diskless stars in the Serpens Molecular Cloud, identified at X-ray wavelengths. Spectral types, effective temperatures and stellar luminosities were determined using the optical spectra and optical/near-IR photometry. Stellar masses and ages were derived based on PMS evolutionary tracks. The results yield remarkable similarities for age and mass distribution between the diskless and disk-bearing stellar populations in Serpens. We discuss the important impli- cations these similarities may have on the standard picture of disk evolution. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.2967v1.pdf"}
{"id": "1308.4502", "abstract": "  We performed magnetic and ferroelectric measurements, associated with Landau theory and symmetry analysis, in order to clarify the situation of the YMnO3 system, a classical example of type I multiferroics. We found that the only magnetic group compatible with all experimental data (neutrons scattering, magnetization,polarization, dielectric constant, second harmonic generation) is the P6'3 group. In this group a small ferromagnetic component along c is induced by the Dzyaloshinskii-Moriya interaction, and observed here in SQUID magnetization measurements. We found that the ferromagnetic and antiferromagnetic components can only be switched simultaneously, while the magnetic orders are functions of the polarization square and therefore insensitive to its sign. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.4502v1.pdf"}
{"id": "1308.4593", "abstract": "  Advances in reflectarrays and array lenses with electronic beam-forming capabilities are enabling a host of new possibilities for these high-performance, low-cost antenna architectures. This paper reviews enabling technologies and topologies of reconfigurable reflectarray and array lens designs, and surveys a range of experimental implementations and achievements that have been made in this area in recent years. The paper describes the fundamental design approaches employed in realizing reconfigurable designs, and explores advanced capabilities of these nascent architectures, such as multi-band operation, polarization manipulation, frequency agility, and amplification. Finally, the paper concludes by discussing future challenges and possibilities for these antennas. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.4593v1.pdf"}
{"id": "1308.4700", "abstract": "  A century after Victor Hess' discovery of cosmic rays, balloon flights still play a central role in the investigation of cosmic rays over nearly their entire spectrum. We report on the current status of NASA balloon program for particle astrophysics, with particular emphasis on the very successful Antarctic long-duration balloon program, and new developments in the progress toward ultra-long duration balloons. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.4700v2.pdf"}
{"id": "1308.5059", "abstract": "  White-light emissions were observed from an X1.7 class solar flare on 27 January 2012, using three continuum bands (red, green, and blue) of the Solar Optical Telescope (SOT) onboard the Hinode satellite. This event occurred near the solar limb, and so differences in locations of the various emissions are consistent with differences in heights above the photosphere of the various emission sources. Under this interpretation, our observations are consistent with the white-light emissions occurring at the lowest levels of where the Ca II H emission occurs. Moreover, the centers of the source regions of the red, green, and blue wavelengths of the white-light emissions are significantly displaced from each other, suggesting that those respective emissions are emanating from progressively lower heights in the solar atmosphere. The temperature distribution was also calculated from the white-light data, and we found the lower-layer emission to have a higher temperature. This indicates that high-energy particles penetrated down to near the photosphere, and deposited heat into the ambient lower layers of the atmosphere. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.5059v1.pdf"}
{"id": "1308.5743", "abstract": "  Starting from the geometrical concept of a 4-dimensional de-Sitter configuration of spheres in Euclidean 3-space and modelling voids in the Universe as spheres, we show that a uniform distribution over this configuration space implies a power-law for the void number density which is consistent with results from the excursion set formalism and with data, for an intermediate range of void volumes. The scaling dimension of the large scale structure can be estimated as well. We also discuss the effect of restricting the survey geometry on the void statistics. This work is a new application of de-Sitter geometry to cosmology and also provides a new geometrical perspective on self-similarity in cosmology. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.5743v2.pdf"}
{"id": "1308.5938", "abstract": "  Shaping gain is attained in schemes where a shaped subcode is chosen from a larger codebook by a codeword selection process. This includes the popular method of Trellis Shaping (TS), originally proposed by Forney for average power reduction. The decoding process of such schemes is mismatched, since it is aware of only the large codebook. This study models such schemes by a random code construction and derives achievable bounds on the transmission rate under matched and mismatched decoding. For matched decoding the bound is obtained using a modified asymptotic equipartition property (AEP) theorem derived to suit this particular code construction. For mismatched decoding, relying on the large codebook performance is generally wrong, since the performance of the non-typical codewords within the large codebook may differ substantially from the typical ones. Hence, we present two novel lower bounds on the capacity under mismatched decoding. The first is based upon Gallager's random exponent, whereas the second on a modified version of the joint-typicality decoder. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.5938v1.pdf"}
{"id": "1308.6825", "abstract": "  A long laser beam propagating through an underdense plasma produces a positively charged ion channel by expelling plasma electrons in the transverse direction. We consider the dynamics of a test electron in a resulting two-dimensional channel under the action of the laser field and the transverse electric field of the channel. A considerable enhancement of the axial momentum can be achieved in this case via amplification of betatron oscillations. It is shown that the oscillations can be parametrically amplified when the betatron frequency, which increases with the wave amplitude, becomes comparable to the frequency of its modulations. The modulations are caused by non-inertial (accelerated/decelerated) relativistic axial motion induced by the wave regardless of the angle between the laser electric field and the field of the channel. We have performed a parameter scan for a wide range of wave amplitudes and ion densities and we have found that, for a given density, there is a well pronounced wave amplitude threshold above which the maximum electron energy is considerably enhanced. We have also calculated a time-integrated electron spectrum produced by an ensemble of electrons with a spread in the initial transverse momentum. The numerical results show that the considerable energy enhancement is accompanied by spectrum broadening. The presented mechanism of energy enhancement is robust with respect to an axial increase of ion density, because it relies on a threshold phenomenon rather than on a narrow linear resonance. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.6825v1.pdf"}
{"id": "1309.1168", "abstract": "  Double-mode RR Lyr type stars are important for studies of properties of horizontal-branch stars. In particular, two periods coupled with spectral properties give a mass estimate that is independent of evolutionary models. Here, we present 59 new Galactic double-mode RR Lyr stars found in the LINEAR survey data with the fundamental radial mode and the first overtone exited (RRd stars). These stars may be useful for constraining the mass-metallicity relation for field horizontal-branch stars. Also, new RRd stars found in the LMC by EROS-II are verified. We present the updated Petersen diagram and the distribution of the fundamental mode periods. Comments on selected variable stars from LINEAR and LMC EROS-II surveys are also presented, including very rare objects: the third known mode-switching RR Lyr and Cepheid pulsating simultaneously in three radial modes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.1168v3.pdf"}
{"id": "1309.2645", "abstract": "  The problem of explaining the X-ray emission properties of the massive, close binary WR 20a is discussed. Located near the cluster core of Westerlund 2, WR 20a is composed of two nearly identical Wolf- Rayet stars of 82 and 83 solar masses orbiting with a period of only 3.7 days. Although Chandra observations were taken during the secondary optical eclipse, the X-ray light curve shows no signs of a flux decrement. In fact, WR 20a appears slightly more X-ray luminous and softer during the optical eclipse, opposite to what has been observed in other binary systems. To aid in our interpretation of the data, we compare with the results of hydrodynamical simulations using the adaptive mesh refinement code Mezcal that includes radiative cooling and a radiative acceleration force term. It is shown that the X-ray emission can be successfully explained in models where the wind-wind collision interface in this system occurs while the outflowing material is still being accelerated. Consequently, WR 20a serves as a critical test-case for how radiatively-driven stellar winds initiate and interact. Our models not only procure a robust description of current Chandra data, which cover the orbital phases between 0.3 to 0.6, but provide detailed predictions over the entire orbit. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.2645v2.pdf"}
{"id": "1309.2880", "abstract": "  We have demonstrated stabilization of a fiber-optic Mach-Zehnder interferometer, with a centimeter-scale path difference, to the transmission minimum for the carrier wave of a frequency-modulated laser beam. A time-averaged extinction of 32 dB, limited by the bandwidth of the feedback, was maintained over several hours. The interferometer was used to remove the carrier wave from a 780 nm laser beam that had been phase modulated at 2.7 GHz. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.2880v1.pdf"}
{"id": "1309.3410", "abstract": "  We analyze the stability of a thin plasma disk which is rotating around a compact astrophysical object and is embedded in the strong magnetic field of such a source. The aim of this study is the determination of a new type of unstable modes, able to replace the magneto-rotational instability profile for low beta-values and for sufficiently small scales of the perturbations, where it fails. In particular, we consider the magneto-hydrodynamical scheme including a non-zero Nernst coefficient, corresponding to first-order collisional effects. As a result, modes with imaginary frequency lead to an instability regime when the magnetic tension vanishes. Finally, we show that, even in the presence of resistive effects, it remains a good candidate to ensure the onset of a turbulent behavior in the absence of the magneto-rotational instability. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.3410v2.pdf"}
{"id": "1309.4314", "abstract": "  The star HD 51844 was observed in CoRoT LRa02 as a Seismo target which turned out to be an SB2 system. The 117 days long light curve revealed delta Scuti pulsation in the range of 6 to 15 d^-1 where four frequencies have amplitudes larger than 1.4 mmag and a rich frequency spectrum with amplitudes lower than 0.6 mmag. Additionally, the light curve exhibits a brightening event recurring every 33.5 days with a maximum of 3 mmag and a duration of about 5 days. Thus, this star can be considered as a heartbeat candidate. The radial velocities from spectroscopy confirmed an eccentric binary system with nearly identical masses and physical parameters. The brightening event of the light curve coincides with the maximum radial velocity separation showing that the brightening is in fact caused by tidal distortion and/or reflected light. One component displays large line profile variations, while the other does not show significant variation. The frequency analysis revealed a quintuplet structure of the four highest-amplitude frequencies, which is due to the orbital motion of the pulsating star. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.4314v1.pdf"}
{"id": "1309.5358", "abstract": "  Arrays of circuit cavities offer fascinating perspectives for exploring quantum many-body systems in a driven dissipative regime where excitation losses are continuously compensated by coherent input drives. Here we investigate a system consisting of three transmission line resonators, where the two outer ones are driven by coherent input sources and the central resonator interacts with a superconducting qubit. Whereas a low excitation number regime of such a device has been considered previously with a numerical integration, we here specifically address the high excitation density regime. We present analytical approximations to these regimes in the form of two methods. The first method is a Bogoliubov or linear expansion in quantum fluctuations which can be understood as an approximation for weak nonlinearities. As the second method we introduce a combination of mean-field decoupling for the photon tunneling with an exact approach to a driven Kerr nonlinearity which can be understood as an approximation for low tunneling rates. In contrast to the low excitation regime we find that for high excitation numbers the anti-bunching of output photons from the central cavity does not monotonously disappear as the tunnel coupling between the resonators is increased. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.5358v2.pdf"}
{"id": "1309.5959", "abstract": "  In this review we focus on non-linear phenomena in pulsating stars the mode selection and amplitude limitation. Of many linearly excited modes only a fraction is detected in pulsating stars. Which of them and why (the problem of mode selection) and to what amplitude (the problem of amplitude limitation) are intrinsically non-linear and still unsolved problems. Tools for studying these problems are briefly discussed and our understanding of mode selection and amplitude limitation in selected groups of self-excited pulsators is presented. Focus is put on classical pulsators (Cepheids and RR Lyrae stars) and main sequence variables (delta Scuti and beta Cephei stars). Directions of future studies are briefly discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.5959v1.pdf"}
{"id": "1309.6118", "abstract": "  We present a comprehensive study of the spectral and transport properties in the Anderson–Holstein model both in and out of equilibrium using the functional renormalization group (FRG). We show how the previously established machinery of Matsubara and Keldysh FRG can be extended to include the local phonon mode. Based on the analysis of spectral properties in equilibrium we identify different regimes depending on the strength of the electron–phonon interaction and the frequency of the phonon mode. We supplement these considerations with analytical results from the Kondo model. We also calculate the non-linear differential conductance through the Anderson–Holstein quantum dot and find clear signatures of the presence of the phonon mode. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.6118v1.pdf"}
{"id": "1309.6167", "abstract": "  The interaction of a cavity with an external field is symmetric under time reversal. Thus, coupling to a resonator is most efficient when the incident light is the time reversed version of a free cavity decay, i.e. when it has a rising exponential shape matching the cavity lifetime. For light entering the cavity from only one side, the maximally achievable coupling efficiency is limited by the choice of the cavity mirrors' reflectivities. Such an empty-cavity experiment serves also as a model system for single-photon single-atom absorption dynamics. We present experiments coupling exponentially rising pulses to a cavity system which allows for high coupling efficiencies. The influence of the time constant of the rising exponential is investigated as well as the effect of a finite pulse duration. We demonstrate coupling 94", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.6167v1.pdf"}
{"id": "1309.6205", "abstract": "  We study the dynamics of a single and a pair of vortices in quasi two-dimensional Bose-Einstein condensates at finite temperatures. We use the stochastic Gross-Pitaevskii equation, which is the Langevin equation for the Bose-Einstein condensate, to this end. For a pair of vortices, we study the dynamics of both the vortex-vortex and vortex-antivortex pairs, which are generated by rotating the trap and moving the Gaussian obstacle potential, respectively. Due to thermal fluctuations, the constituent vortices are not symmetrically generated with respect to each other at finite temperatures. This initial asymmetry coupled with the presence of random thermal fluctuations in the system can lead to different decay rates for the component vortices of the pair, especially in the case of two corotating vortices. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.6205v2.pdf"}
{"id": "1309.7224", "abstract": "  We investigate the effect of site-disorder on the superconducting (SC) state in the attractive Hubbard model within the framework of dynamical mean field theory. For a fixed interaction strength (U), the SC order parameter (OP) decreases monotonically with increasing disorder (x), while the single-particle spectral gap (SG) decreases for small x, reaches a minimum and keeps increasing for larger x. Thus, the system remains gapped beyond the destruction of the superconducting state, indicating a disorder-driven superconductor-insulator transition. We investigate this transition in depth considering the effects of weak and strong disorder for a range of interaction strengths. In the clean case, the order-parameter is known to increase monotonically with increasing interaction, saturating at a finite value asymptotically for U→∞. The presence of disorder results in destruction of superconductivity at large U, thus drastically modifying the clean case behaviour. A physical understanding of our findings is obtained by invoking particle-hole asymmetry and the probability distributions of the order parameter and spectral gap. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.7224v1.pdf"}
{"id": "1309.7307", "abstract": "  Two ultracold atom clouds, each separately in a dipole-blockade regime, realize a source of entangled atom pairs that can be ejected on demand. Entanglement generation and ejection is due to resonant dipole-dipole interactions, while van-der-Waals interactions are predominantly responsible for the blockade that ensures the ejection of a single atom per cloud. A source of entangled atoms using these effects can operate with a 10 kHz repetition rate producing ejected atoms with velocities of about 0.5 m/s. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.7307v1.pdf"}
{"id": "1309.7855", "abstract": "  Several scenarios explaining how filaments are formed can be found in literature. In this paper, we analyzed the observations of an active region filament and critically evaluated the observed properties in the context of current filament formation models. This study is based on multi-height spectropolarimetric observations. The inferred vector magnetic field has been extrapolated starting either from the photosphere or from the chromosphere. The line-of-sight motions of the filament, which was located near disk center, have been analyzed inferring the Doppler velocities. We conclude that a part of the magnetic structure emerged from below the photosphere. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.7855v1.pdf"}
{"id": "1310.0553", "abstract": "  Although more than eight decades have passed since P. Th. Oosterhoff drew attention to differences in the properties of RR Lyrae variables in globular clusters, the origin and significance of the Oosterhoff groups remain unclear. Nonetheless, the accumulation of extensive new observations of RR Lyrae stars in globular clusters of the Milky Way and Local Group galaxies allows a fresh look at the phenomenon. Insights come not only from surveys of variables within the original Oosterhoff groups I and II but also from recent observations of the Oosterhoff-intermediate systems found especially in smaller Local Group galaxies. We will compare properties of RR Lyrae in several systems to investigate what they reveal about system-to-system differences of transition temperature between fundamental-mode and first overtone pulsators and of horizontal branch luminosity. Both transition temperature and horizontal branch luminosity have at various times been credited as playing roles in the creation of the Oosterhoff dichotomy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.0553v1.pdf"}
{"id": "1310.0660", "abstract": "  Laboratory based searches for weakly-interacting slim particles (WISPs) of the light-shining-through-a-wall type (LSW) use visible or near-infrared (NIR) laser light. Low-noise and highly efficient detectors are necessary to improve over previous experiments. These requirements overlap with the requirements for single-photon detectors (SPDs) for quantum information (QI) experiments. In this contribution, the sensitivity of several QI SPDs is compared to photo-multiplier tubes (PMTs) and imaging charge-coupled devices (CCDs). It is found that only transition edge sensors (TESs) are viable alternatives to CCDs if the signal can be focussed to a few micro meters. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.0660v1.pdf"}
{"id": "1310.1689", "abstract": "  We consider spin rotations in single- and two-electron quantum dots that are driven by external AC electric field with two mechanisms that couple the electron spatial motion and the spin degree of freedom: the spin-orbit interaction and a random fluctuation of the Overhauser field due to nuclear spin bath. We perform a systematic numerical simulation of the driven system using a finite difference approach with an exact account taken for the electron-electron correlation. The simulation demonstrates that the electron oscillation in fluctuating nuclear field is translated into an effective magnetic field during the electron wave packet motion. The effective magnetic field drives the spin transitions according to the electric-dipole spin resonance mechanism. We find distinct signatures of selection rules for direct and higher-order transitions in terms of the spin-orbital symmetries of the wave functions. The selection rules are violated by the random fluctuation of the Overhauser field. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.1689v1.pdf"}
{"id": "1310.3185", "abstract": "  The spatial organization of enzymes often plays a crucial role in the functionality and efficiency of enzymatic pathways. To fully understand the design and operation of enzymatic pathways, it is therefore crucial to understand how the relative arrangement of enzymes affects pathway function. Here we investigate the effect of enzyme localization on the flux of a minimal two-enzyme pathway within a reaction-diffusion model. We consider different reaction kinetics, spatial dimensions, and loss mechanisms for intermediate substrate molecules. Our systematic analysis of the different regimes of this model reveals both universal features and distinct characteristics in the phenomenology of these different systems. In particular, the distribution of the second pathway enzyme that maximizes the reaction flux undergoes a generic transition from co-localization with the first enzyme when the catalytic efficiency of the second enzyme is low, to an extended profile when the catalytic efficiency is high. However, the critical transition point and the shape of the extended optimal profile is significantly affected by specific features of the model. We explain the behavior of these different systems in terms of the underlying stochastic reaction and diffusion processes of single substrate molecules. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.3185v1.pdf"}
{"id": "1310.3821", "abstract": "  Recent observations of accreting black holes reveal the presence of quasi-periodic oscillations (QPO) in the optical power density spectra. The corresponding oscillation periods match those found in the X-rays, implying a common origin. Among the numerous suggested X-ray QPO mechanisms, some may also work in the optical. However, their relevance to the broadband – optical through X-ray – spectral properties have not been investigated. For the first time, we discuss the QPO mechanism in the context of the self-consistent spectral model. We propose that the QPOs are produced by Lense-Thirring precession of the hot accretion flow, whose outer parts radiate in the optical wavelengths. At the same time, its innermost parts are emitting the X-rays, explaining the observed connection of QPO periods. We predict that the X-ray and optical QPOs should be either in phase or shifted by half a period, depending on the observer position. We investigate the QPO harmonic content and find that the variability amplitudes at the fundamental frequency are larger in the optical, while the X-rays are expected to have strong harmonics. We then discuss the QPO spectral dependence and compare the expectations to the existing data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.3821v1.pdf"}
{"id": "1310.4234", "abstract": "  A liquid droplet resting on a soft gel substrate can deform that substrate to the point of material failure, whereby fractures develop on the gel surface that propagate outwards from the contact-line in a starburst pattern. In this paper, we characterize i) the initiation process in which the number of arms in the starburst is controlled by the ratio of surface tension contrast to the gel's elastic modulus and ii) the propagation dynamics showing that once fractures are initiated they propagate with a universal power law L∝ t^3/4. We develop a model for crack initiation by treating the gel as a linear elastic solid and computing the deformations within the substrate from the liquid/solid wetting forces. The elastic solution shows that both the location and magnitude of the wetting forces are critical in providing a quantitative prediction for the number of fractures and, hence, an interpretation of the initiation of capillary fractures. This solution also reveals that the depth of the gel is an important factor in the fracture process, as it can help mitigate large surface tractions; this finding is confirmed with experiments. We then develop a model for crack propagation by considering the transport of an inviscid fluid into the fracture tip of an incompressible material, and find that a simple energy-conservation argument can explain the observed material-independent power law. We compare predictions for both linear elastic and neo-Hookean solids finding that the latter better explains the observed exponent. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.4234v1.pdf"}
{"id": "1310.4416", "abstract": "  We consider the \"two flavour\" Nambu–Jona-Lasinio model in the presence of a vector and an axial external chemical potentials and study the phase structure of the model at zero temperature. The Nambu–Jona-Lasinio model is often used as a toy replica of QCD and it is therefore interesting to explore the consequences of adding external vector and axial chemical potentials in this model, mostly motivated by claims that such external drivers could trigger a phase where parity could be broken in QCD. We are also motivated by some lattice analysis that attempt to understand the nature of the so-called Aoki phase using this simplified model. Analogies and differences with the expected behaviour in QCD are discussed and the limitations of the model are pointed out. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.4416v3.pdf"}
{"id": "1310.5265", "abstract": "  New spectral line polarisation observations of 7 bright Ap stars have been obtained with the ESPaDOnS and Narval high resolution spectropolarimeters (Silvester et al. 2012). The aim of this data set is produce a series of surface magnetic field and surface chemistry maps for these Ap stars. We present new magnetic maps for the Ap star α^2 CVn using these new data and the MDI inversion code INVERS10. α^2 CVn is the first Ap star to be observed during two separate epochs using high resolution phase resolved spectropolarimetric IQUV observations and as such allows us an insight into how stable the surface magnetic structure is over a decade timescale. We show that the new maps give a magnetic field structure consistent with the previous maps obtained by Kochukhov and Wade (2010) from lower quality MuSiCoS spectra taken a decade ago and that the field topology cannot be described by a dipolar or quadrupolar field. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.5265v1.pdf"}
{"id": "1311.2695", "abstract": "  We calculate the effect of spin waves on the properties of finite size spin chains with a chiral spin ground state observed on bi-atomic Fe chains deposited on Iridium(001). The system is described with a Heisenberg model supplemented with a Dzyaloshinskii-Moriya (DM) coupling and a uniaxial single ion anisotropy that presents a chiral spin ground state. Spin waves are studied using the Holstein-Primakoff (HP) boson representation of spin operators. Both the renormalized ground state and the elementary excitations are found by means of Bogoliubov transformation, as a function of the two variables that can be controlled experimentally, the applied magnetic field and the chain length. Three main results are found. First, because of the non-collinear nature of the classical ground state, there is a significant zero point reduction of the ground state magnetization of the spin spiral. Second, the two lowest energy spin waves are edge modes in the spin spiral state that, above a critical field the results into a collinear ferromagnetic ground state, become confined bulk modes. Third, in the spin spiral state, the spin wave spectrum exhibits oscillatory behavior as function of the chain length with the same period of the spin helix. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1311/1311.2695v1.pdf"}
{"id": "1311.5527", "abstract": "  We consider the problem of spectrum sharing in device-to-device communication systems. Inspired by the recent optimality condition for treating interference as noise, we define a new concept of \"information-theoretic independent sets\" (ITIS), which indicates the sets of links for which simultaneous communication and treating the interference from each other as noise is information-theoretically optimal (to within a constant gap). Based on this concept, we develop a new spectrum sharing mechanism, called \"information-theoretic link scheduling\" (ITLinQ), which at each time schedules those links that form an ITIS. We first provide a performance guarantee for ITLinQ by characterizing the fraction of the capacity region that it can achieve in a network with sources and destinations located randomly within a fixed area. Furthermore, we demonstrate how ITLinQ can be implemented in a distributed manner, using an initial 2-phase signaling mechanism which provides the required channel state information at all the links. Through numerical analysis, we show that distributed ITLinQ can outperform similar state-of-the-art spectrum sharing mechanisms, such as FlashLinQ, by more than a 100", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1311/1311.5527v3.pdf"}
{"id": "1311.7324", "abstract": "  Simulations using 3D and 2D full-wave codes have shown that edge filaments in tokamak plasmas can significantly affect the propagation of microwaves across a broad frequency spectrum, resulting in scattering angles of up to 46 degrees. Parameter scans were carried out for density perturbations comparable in width and amplitude to MAST filaments and the effect on the measured emission was calculated. 3D effects were discovered in the case of an obliquely incident beam.   In general, the problem of EM propagation past wavelength-sized 3D inhomogeneities is not well understood, yet is of importance for both heating and diagnostic applications in the electron cyclotron frequency range for tokamaks, as well as atmospheric physics. To improve this understanding, a new cold-plasma code, EMIT-3D, was written to extend full-wave microwave simulations in magnetized plasmas to 3D, and make comparisons to the existing 2D code IPF-FDMC. This work supports MAST experiments using the SAMI diagnostic to image microwave emission from the plasma edge due to mode conversion from electron Bernstein waves. Significant fluctuations in the SAMI data mean that detailed modelling is required to improve its interpretation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1311/1311.7324v1.pdf"}
{"id": "1312.2499", "abstract": "  Analysis of signal fluctuations of a locally fixed probe, caused by molecules diffusing under the probe, can be used to determine diffusion coefficients. Theoretical treatments so far have been limited to point-like particles or to molecules with circle-like shapes. Here we extend these treatments to molecules with rectangle-like shapes, for which also rotational diffusion needs to be taken into account. Focusing on the distribution of peak widths in the signal, we show how translational as well as rotational diffusion coefficients can be determined. We address also the question, how the distribution of interpeak time intervals and autocorrelation function can be employed for determining diffusion coefficients. Our approach is validated against kinetic Monte Carlo simulations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.2499v1.pdf"}
{"id": "1312.3963", "abstract": "  Over the last decade, quasar sample sizes have increased from several thousand to several hundred thousand, thanks mostly to SDSS imaging and spectroscopic surveys. LSST, the next-generation optical imaging survey, will provide hundreds of detections per object for a sample of more than ten million quasars with redshifts of up to about seven. We briefly review optical quasar selection techniques, with emphasis on methods based on colors, variability properties and astrometric behavior. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.3963v1.pdf"}
{"id": "1312.4204", "abstract": "  We present a model where the lepton masses are the eigenvalues of relativistic nonlinear field equations. The eigenfunctions correspond in the model to lepton states with inner structure. In this picture the self-interaction leads to the bound state of electron described by the ground state solution. The variational approach based on minimization of the mass or the energy of the ground state solution is developed. The analytical solution yields the relation between the coupling constant G_l of the self-interaction and the electron mass as m_e≃ 2.3√(ħ c/G_l). This solution also leads to a finite `radius' of the electron which is about 1.9λ_e where λ_e is the Compton length of electron. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.4204v1.pdf"}
{"id": "1312.5833", "abstract": "  Entanglement behavior for different classes of two qubit systems passing through a generalized amplitude damping channel is discussed. The phenomena of sudden single, double changes and the sudden death of entanglement are reported for correlated and non- correlated noise. It is shown that, for less entangled states, these phenomena appear for small values of channel strength. The effect of the channel can be frozen for these classes as one increases the channel strength. Maximum entangled states are more fragile than partial entangled states, where the entanglement decays very fast. However, one can not freeze the effect of the noise channel for systems initially prepared in maximum entangled states. The decay rate of entanglement for systems affected by non-correlated noise is much larger than that affected by correlated noise. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.5833v1.pdf"}
{"id": "1312.6984", "abstract": "  Using combined theoretical and experimental approaches, we studied the structural and electronic origin of the magnetic structure in hexagonal LuFeO_3. Besides showing the strong exchange coupling that is consistent with the high magnetic ordering temperature, the previously observed spin reorientation transition is explained by the theoretically calculated magnetic phase diagram. The structural origin of this spin reorientation that is responsible for the appearance of spontaneous magnetization, is identified by theory and verified by x-ray diffraction and absorption experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.6984v3.pdf"}
{"id": "1401.0254", "abstract": "  I review a class of nonlocally modified gravity models which were proposed to explain the current phase of cosmic acceleration without dark energy. Among the topics considered are deriving causal and conserved field equations, adjusting the model to make it support a given expansion history, why these models do not require an elaborate screening mechanism to evade solar system tests, degrees of freedom and kinetic stability, and the negative verdict of structure formation. Although these simple models are not consistent with data on the growth of cosmic structures many of their features are likely to carry over to more complicated models which are in better agreement with the data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.0254v1.pdf"}
{"id": "1401.0675", "abstract": "  A key quantity characterizing a time-periodically forced quantum system coupled to a heat bath is the energy flowing in the steady state through the system into the bath, where it is dissipated. We derive a general expression which allows one to compute this energy dissipation rate for a heat bath consisting of a large number of harmonic oscillators, and work out two analytically solvable model examples. In particular, we distinguish between genuine transitions effectuating a change of the systems's Floquet state, and pseudo-transitions preserving that state; the latter are shown to yield an important contribution to the total dissipation rate. Our results suggest possible driving-mediated heating and cooling schemes on the quantum level. They also indicate that a driven system does not necessarily occupy only a single Floquet state when being in contact with a zero-temperature bath. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.0675v1.pdf"}
{"id": "1401.2578", "abstract": "  We establish the spectral line shape of orbital excitations created by resonant inelastic X-ray scattering for the model Mott insulator CoO. Improved experimental energy resolution reveals that the line shapes are strikingly different from expectations in a first principles-based atomic multiplet model. Extended theoretical simulations are performed to identify the underlying physical origins, which include a pronounced thermal tail reminiscent of anti-Stokes scattering on the energy gain side of excitations, and an essential contribution from interatomic many-body dynamics on the energy loss side of excitations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.2578v1.pdf"}
{"id": "1401.3295", "abstract": "  Weakly Interacting Massive Particles (WIMPs) are well-established dark matter candidates. WIMP interactions with sensitive detectors are expected to display a characteristic annual modulation in rate. We release a dataset spanning 3.4 years of operation from a low-background germanium detector, designed to search for this signature. A previously reported modulation persists, concentrated in a region of the energy spectrum populated by an exponential excess of unknown origin. Its phase and period agree with phenomenological expectations, but its amplitude is a factor ∼4-7 larger than predicted for a standard WIMP galactic halo. We consider the possibility of a non-Maxwellian local halo velocity distribution as a plausible explanation, able to help reconcile recently reported WIMP search anomalies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.3295v1.pdf"}
{"id": "1401.4070", "abstract": "  We develop a framework for modelling the Milky Way using stellar streams and a wide range of photometric and kinematic observations. Through the use of mock data we demonstrate that a standard suite of Galactic observations leads to degeneracies in the inferred halo parameters. We then incorporate a GD-1-like stream into this suite using the orbit-fitting technique and show that the streams reduces the uncertainties in these parameters provided all observations are fit simultaneously. We also explore how the assumption of a disk-halo alignment can lead unphysical models. Our results may explain why some studies based on the Sagittarius stream find that the halo's intermediate axis is parallel to the disk spin axis even though such a configuration is highly unstable. Finally we show that both longer streams and multiple streams lead to improvements in our ability to infer the shape of our dark halo. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.4070v1.pdf"}
{"id": "1401.6030", "abstract": "  The new model of quantum computation is proposed, for which an effective algorithm of solving any task in NP is described. The work is based and inspired be the Grover's algorithm for solving NP-tasks with quadratic speedup compared to the classical computation model. The provided model and algorithm exhibit the exponential speedup over that described by Grover. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.6030v2.pdf"}
{"id": "1401.6857", "abstract": "  For the one-dimensional repulsive Bose gas (Lieb-Liniger model), we study a special class of highly-excited states obtained by giving a finite momentum to subgroups of particles. These states, which correspond to `splitting' the ground state Fermi sea-like quantum number configuration, are zero-entropy states which display interesting properties more normally associated to ground states. Using a numerically exact method based on integrability, we study these states' excitation spectrum, density correlations and momentum distribution functions. These correlations display power-law asymptotics, and are shown to be accurately described by an effective multicomponent Tomonaga-Luttinger liquid theory whose parameters are obtained from Bethe Ansatz. The non-universal correlation prefactors are moreover obtained from integrability, yielding a completely parameter-free fit of the correlator asymptotics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.6857v1.pdf"}
{"id": "1402.1463", "abstract": "  We extend the results of previous work on the vortex order parameter in systems similar to the Ginzburg-Landau description of superfluid ^3He in the bulk B phase. Specifically, we consider vortices preserving an axial U(1) symmetry. We determine the conditions required by the β_i parameters to allow for an energetically favorable development of the off-diagonal antisymmetric and symmetric-traceless elements satisfying the axial symmetry from the trace-only ansatz of the order parameter. The number and type of gapless moduli appearing on the classical low energy theory of axial vortices is determined. The time-dependent part of the Ginzburg-Landau free energy is then considered to determine the number of quantized modes emerging from the gapless moduli fields. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.1463v2.pdf"}
{"id": "1402.3037", "abstract": "  Topological color codes defined by the 4.8.8 semiregular lattice feature geometrically local check operators and admit transversal implementation of the entire Clifford group, making them promising candidates for fault-tolerant quantum computation. Recently, several efficient algorithms for decoding the syndrome of color codes were proposed. Here, we modify one of these algorithms to account for errors affecting the syndrome, applying it to the family of triangular 4.8.8 color codes encoding one logical qubit. For a three-dimensional bit-flip channel, we report a threshold error rate of 0.0208(1), compared with 0.0305(4) previously reported for an integer-program-based decoding algorithm. When we account for circuit details, this threshold is reduced to 0.00143(1) per gate, compared with 0.00672(1) per gate for the surface code under an identical noise model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.3037v1.pdf"}
{"id": "1402.3484", "abstract": "  This paper introduces a new behavioral system model with distinct external and internal signals possibly evolving on different time scales. This allows to capture abstraction processes or signal aggregation in the context of control and verification of large scale systems. For this new system model different notions of simulation and bisimulation are derived, ensuring that they are, respectively, preorders and equivalence relations for the system class under consideration. These relations can capture a wide selection of similarity notions available in the literature. This paper therefore provides a suitable framework for their comparison ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.3484v1.pdf"}
{"id": "1402.4661", "abstract": "  We initially consider a single-particle tight-binding model on the Regularized Apollonian Network (RAN). The RAN is defined starting from a tetrahedral structure with four nodes all connected (generation 0). At any successive generations, new nodes are added and connected with the surrounding three nodes. As a result, a power-law cumulative distribution of connectivity P(k)∝1/k^η with η=ln(3)/ln(2) ≈ 1.585 is obtained.   The eigenvalues of the Hamiltonian are exactly computed by a recursive approach for any size of the network. In the infinite size limit, the density of states and the cumulative distribution of states (integrated density of states) are also exactly determined. The relevant scaling behavior of the cumulative distribution close to the band bottom is shown to be power law with an exponent depending on the spectral dimension and not on the embedding dimension.   We then consider a gas made by an infinite number of non-interacting bosons each of them described by the tight-binding Hamiltonian on the RAN and we prove that, for sufficiently large bosonic density and sufficiently small temperature, a macroscopic fraction of the particles occupy the lowest single-particle energy state forming the Bose-Einstein condensate. We determine no only the transition temperature as a function of the bosonic density, but also the fraction of condensed particle, the fugacity, the energy and the specific heat for any temperature and bosonic density. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.4661v1.pdf"}
{"id": "1402.4831", "abstract": "  We systematically study exclusive diffractive (photo) production of vector mesons (J/ψ, ψ(2s), ϕ and ρ) off protons in high-energy collisions and investigate whether the production is a sensitive probe of gluon saturation. We confront saturation-based results for diffractive ψ(2s) and ρ production at HERA and J/ψ photoproduction with all available data including recent ones from HERA, ALICE and LHCb, finding good agreement. In particular, we show that the t-distribution of differential cross sections of photoproduction of vector mesons offers a unique opportunity to discriminate among saturation and non-saturation models. This is due to the emergence of a pronounced dip (or multiple dips) in the t-distribution of diffractive photoproduction of vector mesons at relatively large, but potentially accessible |t| that can be traced back to the unitarity features of colour dipole amplitude in the saturation regime. We show that in saturation models the dips in t-distribution recede towards lower |t| with decreasing mass of the vector meson, increasing energy or decreasing Bjorken-x, and decreasing virtuality Q. We provide various predictions for exclusive (photo) production of different vector mesons including the ratio of ψ(2s)/J/ψ at HERA, the LHC, and future colliders. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.4831v3.pdf"}
{"id": "1402.7084", "abstract": "  We study one-dimensional lattices of interacting spins-1/2 and show that the effects of quenching the amplitude of a local magnetic field applied to a single site of the lattice can be comparable to the effects of a global perturbation applied instantaneously to the entire system. Both quenches take the system to the chaotic domain, the energy distribution of the initial states approaches a Breit-Wigner shape, the fidelity (Loschmidt echo) decays exponentially, and thermalization becomes viable. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.7084v2.pdf"}
{"id": "1403.1072", "abstract": "  Some severe constraints on asymmetric dark matter are based on the scenario that certain types of WIMPs can form mini-black holes inside neutron stars that can lead to their destruction. A crucial element for the realization of this scenario is that the black hole grows after its formation (and eventually destroys the star) instead of evaporating. The fate of the black hole is dictated by the two opposite mechanics i.e. accretion of nuclear matter from the center of the star and Hawking radiation that tends to decrease the mass of the black hole. We study how the assumptions for the accretion rate can in fact affect the critical mass beyond which a black hole always grows. We also study to what extent degenerate nuclear matter can impede Hawking radiation due to the fact that emitted particles can be Pauli blocked at the core of the star. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.1072v1.pdf"}
{"id": "1403.2999", "abstract": "  We put forward an experimental configuration to observe transverse Anderson localization of partially coherent light beams with a tunable degree of first-order coherence. The scheme makes use of entangled photons propagating in disordered waveguide arrays, and is based on the unique relationship between the degree of entanglement of a pair of photons and the coherence properties of the individual photons constituting the pair. The scheme can be readily implemented with current waveguide-on-a-chip technology, and surprisingly, the tunability of the coherence properties of the individual photons is done at the measurement stage, without resorting changes of the light source itself. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.2999v3.pdf"}
{"id": "1403.3655", "abstract": "  Presentism is, roughly, the metaphysical doctrine that maintains that whatever exists, exists in the present. The compatibility of presentism with the theories of special and general relativity was much debated in recent years. It has been argued that at least some versions of presentism are consistent with time-orientable models of general relativity. In this paper we confront the thesis of presentism with relativistic physics, in the strong gravitational limit where black holes are formed. We conclude that the presentist position is at odds with the existence of black holes and other compact objects in the universe. A revision of the thesis is necessary, if it is intended to be consistent with the current scientific view of the universe. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.3655v1.pdf"}
{"id": "1403.3968", "abstract": "  The magnetic response expected from a state characterized by rotating antiferromagnetism in a neutron-scattering experiment is calculated. We predict the occurrence of a peak at the frequency of the rotation of the rotating antiferromagnetic order parameter. The doping dependence of this frequency is very similar to that of the frequency of the magnetic resonance observed in the neutron-scattering experiments for the hole-doped high-T_C cuprates. This leads us to propose the rotating antiferromagnetism as a possible mechanism for this magnetic resonance. We conclude that while the magnitude of the rotating antiferromagnetic order parameter was previously proposed to be responsible for the pseudogap and the unusual thermodynamic and transport properties, the phase of the rotating order parameter is proposed here to be responsible for the unusual magnetic properties of the high-T_C copper-oxide superconductors. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.3968v2.pdf"}
{"id": "1403.4338", "abstract": "  Motivated by a goal of realizing spin-orbit coupling (SOC) beyond one-dimension (1D), we propose and analyze a method to generate an effective 2D SOC in bilayer BECs with laser-assisted inter-layer tunneling. We show that an interplay between the inter-layer tunneling, SOC and intra-layer atomic interaction can give rise to diverse ground state configurations. In particular, the system undergoes a transition to a new type of stripe phase which spontaneously breaks the time-reversal symmetry. Different from the ordinary Rashba-type SOC, a fractionalized skyrmion lattice emerges spontaneously in the bilayer system without external traps. Furthermore, we predict the occurrence of a tetracritical point in the phase diagram of the bilayer BECs, where four different phases merge together. The origin of the emerging different phases is elucidated. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.4338v2.pdf"}
{"id": "1403.4670", "abstract": "  This paper studies the problem of stabilizing a continuous-time switched linear system by quantized output feedback. We assume that the quantized outputs and the switching signal are available to the controller at all time. We develop an encoding strategy by using multiple Lyapunov functions and an average dwell time property. The encoding strategy is based on the results in the case of a single mode, and it requires an additional adjustment of the \"zoom\" parameter at every switching time. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.4670v1.pdf"}
{"id": "1403.4711", "abstract": "  This paper presents a novel compositional approach to distributed coordination module (CM) synthesis for multiple discrete-event agents in the formal languages and automata framework. The approach is supported by two original ideas. The first is a new formalism called the Distributed Constraint Specification Network (DCSN) that can comprehensibly describe the networking constraint relationships among distributed agents. The second is multiagent conflict resolution planning, which entails generating and using AND/OR graphs to compactly represent conflict resolution (synthesis-process) plans for a DCSN. Together with the framework of local CM design developed in the authors' earlier work, the systematic approach supports separately designing local and deconflicting CM's for individual agents in accordance to a selected conflict resolution plan. Composing the agent models and the CM's designed furnishes an overall nonblocking coordination solution that meets the set of inter-agent constraints specified in a given DCSN. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.4711v1.pdf"}
{"id": "1403.5408", "abstract": "  Using time dependent density functional theory (TDDFT) we examine the energy, angular and time-resolved photoelectron spectra (TRPES) of ethylene in a pump-probe setup. To simulate TRPES we expose ethylene to an ultraviolet (UV) femtosecond pump pulse, followed by a time delayed extreme ultraviolet (XUV) probe pulse. Studying the photoemission spectra as a function of this delay provides us direct access to the dynamic evolution of the molecule's electronic levels. Further, by including the nuclei's motion, we provide direct chemical insight into the chemical reactivity of ethylene. These results show how angular and energy resolved TRPES could be used to directly probe electron and nucleus dynamics in molecules. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.5408v1.pdf"}
{"id": "1403.7350", "abstract": "  We construct electronic oscillator from acellular slime mould Physarum polycephalum. The slime mould oscillator is made of two electrodes connected by a protoplasmic tube of the living slime mould. A protoplasmic tube has an average resistance of 3 MOhm. The tube's resistance is changing over time due to peristaltic contractile activity of the tube. The resistance of the protoplasmic tube oscillates with average period of 73 sec and average amplitude of 0.6 MOhm. We present experimental laboratory results on dynamics of Physarum oscillator under direct current voltage up to 15 V and speculate that slime mould P. polycephalum can be employed as a living electrical oscillator in biological and hybrid circuits. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.7350v1.pdf"}
{"id": "1404.2672", "abstract": "  We study theoretically a three-mode optomechanical system where two mechanical oscillators are independently coupled to a single cavity mode. By optimized two-tone or four-tone driving of the cavity one can prepare the mechanical oscillators in an entangled two-mode squeezed state, even if they start in a thermal state. The highly-pure, symmetric steady-state achieved allows the optimal fidelity of standard continuous-variable teleportation protocols to be achieved. In contrast to other reservoir engineering approaches to generating mechanical entanglement, only a single reservoir is required to prepare the highly-pure entangled steady-state, greatly simplifying experimental implementation. The entanglement may be verified via a bound on the Duan inequality obtained from the cavity output spectrum. A similar technique may be used for the preparation of a highly-pure two-mode squeezed state of two cavity modes, coupled to a common mechanical oscillator. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.2672v3.pdf"}
{"id": "1404.3092", "abstract": "  In this paper we investigate the role of causal heat transport in a spatially homogeneous, locally-rotationally symmetric Bianchi type-V cosmological model. In particular, the causal temperature profile of the cosmological fluid is obtained within the framework of extended irreversible thermodynamics. We demonstrate that relaxational effects can alter the temperature profile when the cosmological fluid is out of hydrostatic equilibrium. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.3092v1.pdf"}
{"id": "1404.3172", "abstract": "  We study scalar perturbations for a four-dimensional asymptotically Lifshitz black hole in conformal gravity with dynamical exponent z=0, and spherical topology for the transverse section, and we find analytically and numerically the quasinormal modes for scalar fields for some special cases. Then, we study the stability of these black holes under scalar field perturbations and the greybody factors. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.3172v3.pdf"}
{"id": "1404.3432", "abstract": "  We study the formation of gap solitons in the presence of parametric pump. It is shown that parametric pump can stabilize stationary solitons continuously emitting dispersive waves. The resonant interactions of the radiation and the solitons are studied and it is shown that the solitons can be effectively controlled by the radiation. In particular it is shown that the solitons can collide or to get pinned to inhomogeneities due to the interactions mediated by the resonant radiation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.3432v1.pdf"}
{"id": "1404.4116", "abstract": "  Melanocytic nevi are benign proliferations that sometimes turn into malignant melanoma in a way that is still unclear from the biochemical and genetic point of view. Diagnostic and prognostic tools are then mostly based on dermoscopic examination and morphological analysis of histological tissues. To investigate the role of mechanics and geometry in the morpholgical dynamics of melanocytic nevi, we study a computation model for cell proliferation in a layered non-linear elastic tissue. Numerical simulations suggest that the morphology of the nevus is correlated to the initial location of the proliferating cell starting the growth process and to the mechanical properties of the tissue. Our results also support that melanocytes are subject to compressive stresses that fluctuate widely in the nevus and depend on the growth stage. Numerical simulations of cells in the epidermis releasing matrix metalloproteinases display an accelerated invasion of the dermis by destroying the basal membrane. Moreover, we suggest experimentally that osmotic stress and collagen inhibit growth in primary melanoma cells while the effect is much weaker in metastatic cells. Knowing that morphological features of nevi might also reflect geometry and mechanics rather than malignancy could be relevant for diagnostic purposes ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.4116v1.pdf"}
{"id": "1404.5288", "abstract": "  The 4D Regge action is invariant under 5–1 and 4–2 Pachner moves, which define a subset of (local) changes of the triangulation. Given this fact one might hope to find a local path integral measure that makes the quantum theory invariant under these moves and hence makes the theory partially triangulation invariant. We show that such a local invariant path integral measure does not exist for the 4D linearized Regge theory.   To this end we uncover an interesting geometric interpretation for the Hessian of the 4D Regge action. This geometric interpretation will allow us to prove that the determinant of the Hessian of the 4D Regge action does not factorize over 4–simplices or subsimplices. It furthermore allows to determine configurations where this Hessian vanishes, which only appears to be the case in degenerate backgrounds or if one allows for different orientations of the simplices.   We suggest a non–local measure factor that absorbs the non–local part of the determinant of the Hessian under 5–1 moves as well as a local measure factor that is preserved for very special configurations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.5288v2.pdf"}
{"id": "1404.5328", "abstract": "  In the case of radon exposure, the spatial distribution of deposited radioactive particles is highly inhomogeneous in the central airways. The objective of this research is to investigate the consequences of this heterogeneity regarding cellular burdens in the bronchial epithelium and to study the possible biological effects on tissue level. Applying a computational fluid dynamics program, the deposition distribution of inhaled radon daughters has been determined in a bronchial airway model for 23 minutes of work in the New Mexico uranium mine corresponding to 0.0129 WLM exposure. A numerical epithelium model based on experimental data has been utilized in order to quantify cellular hits and doses. Finally, a carcinogenesis model considering cell death induced cell cycle shortening has been applied to assess the biological responses. Computations present, that cellular dose may reach 1.5 Gy, which is several orders of magnitude higher than tissue dose. The results are in agreement with the histological finding that the uneven deposition distribution of radon progenies may lead to inhomogeneous spatial distribution of tumours in the bronchial airways. In addition, on macroscopic level, the relationship between cancer risk and radiation burden seems to be non-linear. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.5328v1.pdf"}
{"id": "1404.5924", "abstract": "  Star formation can be triggered by compression from wind or supernova driven shock waves that sweep over molecular clouds. Because these shocks will likely contain processed elements, triggered star formation has been proposed as an explanation for short lived radioactive isotopes (SLRI) in the Solar System. Previous studies have tracked the triggering event to the earliest phases of collapse and have focused on the shock properties required for both successful star formation and mixing of SLRI's. In this paper, we use Adaptive Mesh Refinement (AMR) simulation methods, including sink particles, to simulate the full collapse and subsequent evolution of a stable Bonnor-Ebert sphere subjected to a shock and post-shock wind. We track the flow of the cloud material after a star (a sink particle) has formed. For non-rotating clouds we find robust triggered collapse and little bound circumstellar material remaining around the post-shock collapsed core. When we add initial cloud rotation we observe the formation of disks around the collapsed core which then interact with the post-shock flow. Our results indicate that these circumstellar disks are massive enough to form planets and are long-lived, in spite of the ablation driven by post-shock flow ram pressure. As a function of the initial conditions, we also track the time evolution of the accretion rates and particle mixing between between the ambient wind and cloud material. The latter is maximized for cases of highest mach number. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.5924v1.pdf"}
{"id": "1404.6443", "abstract": "  Based on the Newman-Janis algorithm the Ayon-Beato-Garcia spacetime metric of the regular spherically symmetric, static and charged black hole has been converted into rotational form. It is shown that the derived solution for rotating regular black hole is regular and the critical value of the electric charge Q for which two horizons merge into one sufficiently decreases in the presence of nonvanishing angular momentum a of the black hole. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.6443v1.pdf"}
{"id": "1405.0252", "abstract": "  The minimal geometric deformation approach is employed to show the existence of brane-world stellar distributions with vacuum Schwarzschild exterior, thus without energy leaking from the exterior of the brane-world star into the extra dimension. The interior satisfies all elementary criteria of physical acceptability for a stellar solution, namely, it is regular at the origin, the pressure and density are positive and decrease monotonically with increasing radius, finally all energy conditions are fulfilled. A very thin solid crust with negative radial pressure separates the interior from the exterior, having a thickness Δ inversely proportional to both the brane tension σ and the radius R of the star, i.e. Δ ^-1∼ R σ. This brane-world star with Schwarzschild exterior would appear only thermally radiating to a distant observer and be fully compatible with the stringent constraints imposed on stellar parameters by observations of gravitational lensing, orbital evolutions or properties of accretion disks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.0252v2.pdf"}
{"id": "1405.0329", "abstract": "  A normal Helly circular-arc graph is the intersection graph of arcs on a circle of which no three or less arcs cover the whole circle. Lin, Soulignac, and Szwarcfiter [Discrete Appl. Math. 2013] characterized circular-arc graphs that are not normal Helly circular-arc graphs, and used it to develop the first recognition algorithm for this graph class. As open problems, they ask for the forbidden induced subgraph characterization and a direct recognition algorithm for normal Helly circular-arc graphs, both of which are resolved by the current paper. Moreover, when the input is not a normal Helly circular-arc graph, our recognition algorithm finds in linear time a minimal forbidden induced subgraph as certificate. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.0329v1.pdf"}
{"id": "1405.1263", "abstract": "  Recent studies of dynamical screening of the electronic Coulomb interactions in solids have revived interest in lattice models of correlated fermions coupled to bosonic degrees of freedom (Hubbard-Holstein-type models). We propose a dynamical mean-field-based approach to dynamically screened Coulomb interactions. In the effective Anderson-Holstein model, a transformation to slave rotors [S. Florens and A. Georges, Phys. Rev. B 66, 165111 (2002)] is performed to decouple the dynamical part of the interaction. This transformation allows for a systematic derivation and analysis of recently introduced approximate schemes for the solution of dynamical impurity problems, in particular, the Bose factor ansatz within the dynamic atomic limit approximation (DALA) with and without Lang-Firsov correction. More importantly still, it suggests an optimized choice for a Bose factor in the sense of the variational principle of Feynman and Peierls. We demonstrate the accuracy of our scheme and present a comparison to calculations within the DALA. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.1263v2.pdf"}
{"id": "1405.4326", "abstract": "  Using a scattering matrix approach we study transport in coherent conductors driven by a time-periodic bias voltage. We investigate the role of electron-like and hole-like excitations created by the driving in the energy current noise and we reconcile previous studies on charge current noise in this kind of systems. The energy noise reveals additional features due to electron-hole correlations. These features should be observable in power fluctuations. In particular, we show results for the case of a harmonic and bi-harmonic driving and of Lorentzian pulses applied to a two-terminal conductor, addressing the recent experiments of Refs. 1 and 2. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.4326v2.pdf"}
{"id": "1405.4446", "abstract": "  We propose a protected qubit which is `dual' to a suggestion of a superconducting current mirror qubit [A. Kitaev, arXiv:0609441 (2006)]. Our construction can be regarded as the magnetic analogue of Kitaev's proposal: it inherits the intrinsic fault-tolerance of the current mirror qubit, but may perform better than it in the laboratory, since magnetic noise is generally less of a problem than electric noise. We adapt the scheme for universal fault-tolerant quantum computation proposed by Kitaev to our construction. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.4446v1.pdf"}
{"id": "1406.0386", "abstract": "  The results of phenomenological studies of top-quark pair production in proton-proton collisions are presented. Differential cross sections are calculated in perturbative QCD at approximate next-to-next-to-leading order O(α_s^4) by using methods of threshold resummation beyond the leading logarithmic accuracy. Predictions for the single-particle inclusive kinematics are presented for transverse momentum and rapidity distributions of final-state top quarks. Uncertainties related to the description of proton structure, top-quark mass and strong coupling constant are investigated in detail. The results are compared to the recent measurements by the ATLAS and CMS collaborations at the LHC at the center of mass energy of 7 TeV. The calculation presented here is implemented in the computer code Difftop and can be applied to the general case of heavy-quark pair production at hadron-hadron colliders. For the first time, a fit of parton distribution functions at NNLO is performed by using the differential cross sections of top-quark pair production together with other data sets. The impact of the top-pair production on the precision of the gluon distribution at high scales is illustrated. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.0386v3.pdf"}
{"id": "1406.0515", "abstract": "  I present modeling of the X-ray pulsations from the central compact object (CCO) PSR J1852+0040 in the Galactic supernova remnant Kesteven 79. In the context of thermal surface radiation from a rotating neutron star, a conventional polar cap model can reproduce the broad, large-amplitude X-ray pulse only with a \"pencil plus fan\" beam emission pattern, which is characteristic of strongly magnetized (≳10^12 Gauss) neutron star atmospheres, substantially stronger than the  10^10 Gauss external dipole field inferred from the pulsar spin-down rate. This discrepancy can be explained by an axially displaced dipole. For other beaming patterns, it is necessary to invoke high-aspect-ratio emitting regions that are greatly longitudinally elongated, possibly due to an extremely offset dipole. For all assumed emission models, the existence of strong internal magnetic fields (≳10^14 Gauss) that preferentially channel internal heat to only a portion of the exterior is required to account for the implied high-temperature contrast across the stellar surface. This lends further observational evidence in support of the \"hidden\" strong magnetic field scenario, in which CCOs possess strong submerged magnetic fields that are substantially stronger than the external dipole field, presumably due to burial by fallback of supernova ejecta. I also conduct phase-resolved X-ray spectroscopy and find no evidence for prominent spin-phase-dependent absorption features that could be produced by cyclotron absorption/scattering. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.0515v1.pdf"}
{"id": "1406.1831", "abstract": "  Autoencoders have emerged as a useful framework for unsupervised learning of internal representations, and a wide variety of apparently conceptually disparate regularization techniques have been proposed to generate useful features. Here we extend existing denoising autoencoders to additionally inject noise before the nonlinearity, and at the hidden unit activations. We show that a wide variety of previous methods, including denoising, contractive, and sparse autoencoders, as well as dropout can be interpreted using this framework. This noise injection framework reaps practical benefits by providing a unified strategy to develop new internal representations by designing the nature of the injected noise. We show that noisy autoencoders outperform denoising autoencoders at the very task of denoising, and are competitive with other single-layer techniques on MNIST, and CIFAR-10. We also show that types of noise other than dropout improve performance in a deep network through sparsifying, decorrelating, and spreading information across representations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.1831v1.pdf"}
{"id": "1406.2602", "abstract": "  We consider the problem of learning from a similarity matrix (such as spectral clustering and lowd imensional embedding), when computing pairwise similarities are costly, and only a limited number of entries can be observed. We provide a theoretical analysis using standard notions of graph approximation, significantly generalizing previous results (which focused on spectral clustering with two clusters). We also propose a new algorithmic approach based on adaptive sampling, which experimentally matches or improves on previous methods, while being considerably more general and computationally cheaper. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.2602v1.pdf"}
{"id": "1406.4531", "abstract": "  The causal dynamical triangulations approach aims to construct a quantum theory of gravity as the continuum limit of a lattice-regularized model of dynamical geometry. A renormalization group scheme–in concert with finite size scaling analysis–is essential to this aim. Formulating and implementing such a scheme in the present context raises novel and notable conceptual and technical problems. I explored these problems, and, building on standard techniques, suggested potential solutions in the first paper of this two-part series. As an application of these solutions, I now propose a renormalization group scheme for causal dynamical triangulations. This scheme differs significantly from that studied recently by Ambjorn, Gorlich, Jurkiewicz, Kreienbuehl, and Loll. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.4531v1.pdf"}
{"id": "1406.6212", "abstract": "  We study the entanglement evolution of a quantum optical vortex state propagating through coupled lossless waveguides. We consider states generated by coupling two squeezed modes using a sequence of beam splitters and also by subtracting photons from the signal in spontaneous parametric down conversion. We reconstruct the Wigner function at a later time to study the correlation and quantify the entanglement after propagation using logarithmic negativity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.6212v3.pdf"}
{"id": "1406.6523", "abstract": "  We assess the predictive capabilities of various classes of avalanche models for solar flares. We demonstrate that avalanche models cannot generally be used to predict specific events due to their high sensitivity to their embedded stochastic process. We show that deterministically driven models can nevertheless alleviate this caveat and be efficiently used for large events predictions. Our results promote a new approach for large (typically X-class) solar flares predictions based on simple and computationally inexpensive avalanche models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.6523v1.pdf"}
{"id": "1406.6822", "abstract": "  We constrain the neutrino mass in f(R) gravity using the latest observations from the Planck, BAO and BICEP2 data. We find that the measurement on the B-modes can break the degeneracy between the massive neutrinos and the f(R) gravity. We find a non-zero value of the Compton wavelengths B_0 at a 68% confidence level for the f(R) model in the presence of massive neutrinos when the BICEP2 data is used. Furthermore, the tension on the tensor-to-scalar ratios between the measured values from Plank and BICEP2 is significantly reconciled in our model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.6822v1.pdf"}
{"id": "1406.7073", "abstract": "  Three drugs, Ibuprofen, Aspirin and Erythromycin, are encapsulated in spherical Pluronic F127 micelles. The shapes and the size distributions of the micelles in dilute, aqueous solutions, with and without drugs, are ascertained using cryo- Scanning Electron Microscopy and Dynamic Light Scattering (DLS) experiments, respectively. Uptake of drugs above a threshold concentration is seen to reduce the critical micellization temperature of the solution. The mean hydrodynamic radii and polydispersities of the micelles are found to increase with decrease in temperature and in the presence of drug molecules. The hydration of the micellar core at lower temperatures is verified using fluorescence measurements. Increasing solution pH leads to the ionization of the drugs incorporated in the micellar cores. This causes rupture of the micelles and release of the drugs into the solution at the highest solution pH value of 11.36 investigated here and is studied using DLS and fluorescence spectrocopy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.7073v1.pdf"}
{"id": "1406.7682", "abstract": "  Semi-regular variables (SRVs) though closely related to Mira variables, are a less studied class of AGB stars. While asymmetry in the brightness distribution of many Mira variables is fairly well known, it is detected only in a few SRVs. Asymmetry in the brightness distribution at the level of a few milliarcsecond (mas) can be detected by high angular resolution techniques like lunar occultations (LO), long baseline interferometry, and aperture masking interferometry. Multi-epoch LO observations have the potential to detect a departure of brightness profile from spherical symmetry. Each LO event provides a uniform disk (UD) angular diameter along the position angle of the occultation. Any significant difference in the UD angular diameter values of multi-epoch LO observations signifies a brightness asymmetry. In this paper, we report for the first time three epoch UD angular diameter values of a SRV UZ Arietis using the LO technique at 2.2 μ m. Optical linear polarization of the source observed by us recently is also reported. The asymmetric brightness distribution of UZ Ari suggested by a small difference in the fitted UD values for the three epochs, is discussed in the context of optical polarization exhibited by the source and the direction of polarization axis in the plane of the sky. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.7682v1.pdf"}
{"id": "1407.1998", "abstract": "  We performed a benchmark study on a series of dihydrogen bond complexes and constructed a set of reference bond distances and interaction energies. The test set was employed to assess the performance of several wave-function correlated and density functional theory methods. We found that second-order correlation methods describe relatively well the dihydrogen complexes. However, for high accuracy inclusion of triple contributions is important. On the other hand, none of the considered density functional methods can simultaneously yield accurate bond lengths and interaction energies. However, we found that improved results can be obtained by the inclusion of non-local exchange contributions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.1998v1.pdf"}
{"id": "1407.2012", "abstract": "  The use of Smith-Purcell radiation to measure electrons longitudinal profiles has been demonstrated at several facilities in the picosecond and sub-picosecond range. There is a strong interest for the development of non intercepting longitudinal profile diagnostics for high current proton beams. We present here results of simulations on the expected yield of longitudinal profile monitors using Smith-Purcell radiation for such proton beams. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.2012v1.pdf"}
{"id": "1407.3136", "abstract": "  We present results of axisymmetric magnetohydrodynamic (MHD) simulations investigating the launching of jets and outflows from a magnetically diffusive accretion disk. The time evolution of the disk structure is self-consistently taken into account. In contrast to previous works we have applied spherical coordinates for the numerical grid, implying substantial benefits concerning the numerical resolution and the stability of the simulation. Thanks to the new setup we were able to run simulations for more than 150,000 dynamical times on a domain extending 1500 inner disk radii with a resolution of up to 24 cells per disk height in the inner disk. Depending on the disk magnetization, jet launching occurs in two different but complementary regimes - jets driven predominantly by centrifugal or magnetic forces. These regimes differ in the ejection efficiency concerning mass, energy and angular momentum. We show that it is the actual disk magnetization and not so much the initial magnetization which describes the disk-jet evolution best. Considering the actual disk magnetization we also find that simulations starting with different initial magnetization evolve in a similar - typical - way as due to advection and diffusion the magnetic flux in the disk evolves in time. Exploring a new, modified diffusivity model we confirm the self-similar structure of the global jet-launching disk, obtaining power laws for the radial profiles of the disk physical variables such as density, magnetic field strength, or accretion velocity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.3136v1.pdf"}
{"id": "1407.3168", "abstract": "  We investigate the vector and axial currents induced by external electromagnetic fields and chemical potentials in chiral systems at finite temperature. Similar to the normal Hall effect, we find that an axial Hall current is generated in the presence of the electromagnetic fields along with an axial chemical potential, which may be dubbed as the \"chiral Hall effect\"(CHE). The CHE is related to the interactions of chiral fermions and exists with the a nonzero axial chemical potential. We argue that the CHE could lead to nontrivial charge distributions at different rapidity in asymmetric heavy ion collisions. Moreover, we study the chiral electric waves(CEW) led by the fluctuations of the vector and axial chemical potentials along with the chiral electric separation effect(CESE), where a density wave propagates along the applied electric field. Combining with the normal/chiral Hall effects, the fluctuations of chemical potentials thus result in Hall density waves. The Hall density waves may survive even at zero chemical potentials and become non-dissipative. We further study the transport coefficients including the Hall conductivities, damping times, wave velocities, and diffusion constants of CEW in a strongly coupled plasma via the AdS/CFT correspondence. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.3168v3.pdf"}
{"id": "1407.3448", "abstract": "  We experimentally explore the state space of three qubits on an NMR quantum information processor. We construct a scheme to experimentally realize a canonical form for general three-qubit states up to single-qubit unitaries. This form involves a non-trivial combination of GHZ and W-type maximally entangled states of three qubits. The general circuit that we have constructed for the generic state reduces to those for GHZ and W states as special cases. The experimental construction of a generic state is carried out for a nontrivial set of parameters and the good fidelity of preparation is confirmed by complete state tomography. The GHZ and W-states are constructed as special cases of the general experimental scheme. Further, we experimentally demonstrate a curious fact about three-qubit states, where for almost all pure states, the two-qubit reduced states can be used to reconstruct the full three-qubit state. For the case of a generic state and for the W-state, we demonstrate this method of reconstruction by comparing it with the directly tomographed three-qubit state. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.3448v2.pdf"}
{"id": "1407.3535", "abstract": "  In remote sensing image-blurring is induced by many sources such as atmospheric scatter, optical aberration, spatial and temporal sensor integration. The natural blurring can be exploited to speed up target search by fast template matching. In this paper, we synthetically induce additional non-uniform blurring to further increase the speed of the matching process. To avoid loss of accuracy, the amount of synthetic blurring is varied spatially over the image according to the underlying content. We extend transitive algorithm for fast template matching by incorporating controlled image blur. To this end we propose an Efficient Group Size (EGS) algorithm which minimizes the number of similarity computations for a particular search image. A larger efficient group size guarantees less computations and more speedup. EGS algorithm is used as a component in our proposed Optimizing auto-correlation (OptA) algorithm. In OptA a search image is iteratively non-uniformly blurred while ensuring no accuracy degradation at any image location. In each iteration efficient group size and overall computations are estimated by using the proposed EGS algorithm. The OptA algorithm stops when the number of computations cannot be further decreased without accuracy degradation. The proposed algorithm is compared with six existing state of the art exhaustive accuracy techniques using correlation coefficient as the similarity measure. Experiments on satellite and aerial image datasets demonstrate the effectiveness of the proposed algorithm. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.3535v2.pdf"}
{"id": "1407.3952", "abstract": "  The impact of nonadiabatic laser-induced molecular alignment on filamentation is numerically studied. Weak and strong field model of impulsive molecular alignment are compared in the context of nonlinear pulse propagation. It is shown that the widely used weak field model describing the refractive index modification induced by impulsive molecular alignment accurately reproduces the propagation dynamics providing that only a single pulse is involved during the experiment. On the contrary, it fails at reproducing the nonlinear propagation experienced by an intense laser pulse traveling in the wake of a second strong laser pulse. The discrepancy depends on the relative delay between the two pulses and is maximal for delays corresponding to half the rotational period of the molecule. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.3952v1.pdf"}
{"id": "1407.3965", "abstract": "  Entanglement, one of the most intriguing aspects of quantum mechanics, marks itself into different features of quantum states. For this reason different criteria can be used for verifying entanglement. In this paper we review some of the entanglement criteria casted for continuous variable states and link them to peculiar aspects of the original debate on the famous EPR paradox. Moreover, we give a handy expression for valuating Bell-type non-locality on Gaussian states. We also present the experimental measurement of a particular realization of the Bell operator over continuous variable entangled states produced by a sub-threshold type-II OPO. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.3965v1.pdf"}
{"id": "1407.6771", "abstract": "  This paper presents case studies of the algorithms called \"energy generation and distribution via distributed coordination\", which was proposed in [1-4]. For a convenience, we call \"energy generation and distribution via distributed coordination\" as \"DisCoord Algorithms\". After concisely summarizing the \"DisCoord Algorithms\" in compact forms, we will list several scenarios for numerical tests. Then, while analyzing the simulation results, we will discuss the capability of the algorithms in handling the various cases. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.6771v1.pdf"}
{"id": "1407.7792", "abstract": "  Plane symmetric cosmological models are investigated with or without any dark energy components in the field equations. Keeping an eye on the recent observational constraints concerning the accelerating phase of expansion of the universe, the role of magnetic field is assessed. In the absence of dark energy components, magnetic field can favour an accelerating model even if we take a linear relationship between the directional Hubble parameters. In presence of dark energy components in the form of a time varying cosmological constant, the influence of magnetic field is found to be limited. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.7792v2.pdf"}
{"id": "1407.8509", "abstract": "  RF sensor networks are used to localize people indoor without requiring them to wear invasive electronic devices. These wireless mesh networks, formed by low-power radio transceivers, continuously measure the received signal strength (RSS) of the links. Radio Tomographic Imaging (RTI) is a technique that generates 2D images of the change in the electromagnetic field inside the area covered by the radio transceivers to spot the presence and movements of animates (e.g., people, large animals) or large metallic objects (e.g., cars). Here, we present a RTI system for localizing and tracking people outdoors. Differently than in indoor environments where the RSS does not change significantly with time unless people are found in the monitored area, the outdoor RSS signal is time-variant, e.g., due to rainfalls or wind-driven foliage. We present a novel outdoor RTI method that, despite the nonstationary noise introduced in the RSS data by the environment, achieves high localization accuracy and dramatically reduces the energy consumption of the sensing units. Experimental results demonstrate that the system accurately detects and tracks a person in real-time in a large forested area under varying environmental conditions, significantly reducing false positives, localization error and energy consumption compared to state-of-the-art RTI methods. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.8509v1.pdf"}
{"id": "1407.8513", "abstract": "  Many real-world complex systems are best modeled by multiplex networks. The multiplexity has proved to have broad impact on the system's structure and function. Most theoretical studies on multiplex networks to date, however, have largely ignored the effect of link overlap across layers despite strong empirical evidences for its significance. In this article, we investigate the effect of link overlap in the viability of multiplex networks, both analytically and numerically. Distinctive role of overlapping links in viability and mutual connectivity is emphasized and exploited for setting up proper analytic framework. A rich phase diagram for viability is obtained and greatly diversified patterns of hysteretic behavior in viability are observed in the presence of link overlap. Mutual percolation with link overlap is revisited as a limit of multiplex viability problem, and controversy between existing results is clarified. The distinctive role of overlapping links is further demonstrated by the different responses of networks under random removals of overlapping and non-overlapping links, respectively, as well as under several removal strategies. Our results show that the link overlap strongly facilitates viability and mutual percolation; at the same time, the presence of link overlap poses challenge in analytical approach to the problem. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.8513v1.pdf"}
{"id": "1408.1143", "abstract": "  Machine learning methods are applied to finding the Green's function of the Anderson impurity model, a basic model system of quantum many-body condensed-matter physics. Different methods of parametrizing the Green's function are investigated; a representation in terms of Legendre polynomials is found to be superior due to its limited number of coefficients and its applicability to state of the art methods of solution. The dependence of the errors on the size of the training set is determined. The results indicate that a machine learning approach to dynamical mean-field theory may be feasible. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.1143v2.pdf"}
{"id": "1408.1156", "abstract": "  Although asymptotic analyses of undirected network models based on degree sequences have started to appear in recent literature, it remains an open problem to study statistical properties of directed network models. In this paper, we provide for the first time a rigorous analysis of directed exponential random graph models using the in-degrees and out-degrees as sufficient statistics with binary as well as continuous weighted edges. We establish the uniform consistency and the asymptotic normality for the maximum likelihood estimate, when the number of parameters grows and only one realized observation of the graph is available. One key technique in the proofs is to approximate the inverse of the Fisher information matrix using a simple matrix with high accuracy. Numerical studies confirm our theoretical findings. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.1156v4.pdf"}
{"id": "1408.1494", "abstract": "  What is the role of social interactions in the creation of price bubbles? Answering this question requires obtaining collective behavioural traces generated by the activity of a large number of actors. Digital currencies offer a unique possibility to measure socio-economic signals from such digital traces. Here, we focus on Bitcoin, the most popular cryptocurrency. Bitcoin has experienced periods of rapid increase in exchange rates (price) followed by sharp decline; we hypothesise that these fluctuations are largely driven by the interplay between different social phenomena. We thus quantify four socio-economic signals about Bitcoin from large data sets: price on on-line exchanges, volume of word-of-mouth communication in on-line social media, volume of information search, and user base growth. By using vector autoregression, we identify two positive feedback loops that lead to price bubbles in the absence of exogenous stimuli: one driven by word of mouth, and the other by new Bitcoin adopters. We also observe that spikes in information search, presumably linked to external events, precede drastic price declines. Understanding the interplay between the socio-economic signals we measured can lead to applications beyond cryptocurrencies to other phenomena which leave digital footprints, such as on-line social network usage. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.1494v1.pdf"}
{"id": "1408.1804", "abstract": "  Using Maccaferri's formula, we derive new wedge based solutions of open string field theory. The solutions are gauge equivalent to the Takahashi-Tanimoto scalar solutions. The classical action and the gauge invariant overlap are evaluated analytically. We find a perturbative vacuum solution whose gauge invariant observables vanish. We also identify a tachyon vacuum solution whose gauge invariant observables are identical to those of the Erler-Schnabl solution. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.1804v2.pdf"}
{"id": "1408.2301", "abstract": "  To obtain cm/s precision, stellar surface magneto-convection must be disentangled from observed radial velocities (RVs). In order to understand and remove the convective signature, we create Sun-as-a-star model observations based on a 3D magnetohydrodynamic solar simulation. From these Sun-as-a-star model observations, we find several line characteristics are correlated with the induced RV shifts. The aim of this campaign is to feed directly into future high precision RV studies, such as the search for habitable, rocky worlds, with forthcoming spectrographs such as ESPRESSO. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.2301v2.pdf"}
{"id": "1408.2386", "abstract": "  We consider a process given as the solution of a stochastic differential equation with irregular, path dependent and time-inhomogeneous drift coefficient and additive noise. Explicit and optimal bounds for the Lebesgue density of that process at any given time are derived. The bounds and their optimality is shown by identifying the worst case stochastic differential equation. Then we generalise our findings to a larger class of diffusion coefficients. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.2386v5.pdf"}
{"id": "1408.3626", "abstract": "  Based on a stringy inspired Gauss-Bonnet (GB) modification of classical gravity, we constructed a model for neutron stars. We derived the modified forms of Tolman-Oppenheimer-Volkoff (TOV) equations for a generic function of f(G) gravity. The hydrostatic equations remained unchanged but the dynamical equations for metric functions are modified due to the effects of GB term. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.3626v2.pdf"}
{"id": "1408.5570", "abstract": "  In this paper, we consider Einstein gravity in the presence of a class of nonlinear electrodynamics, called power Maxwell invariant (PMI). We take into account (2+1)-dimensional spacetime in Einstein-PMI gravity and obtain its black hole solutions. Then, we regard pure F(R) gravity as well as F(R)-conformally invariant Maxwell theory to obtain exact solutions of the field equations with black hole interpretation. Finally, we investigate the conserved and thermodynamic quantities and discuss about the first law of thermodynamics for the mentioned gravitational models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.5570v2.pdf"}
{"id": "1408.5899", "abstract": "  We review the basic principles of X-ray polarimetry and current detector technologies based on the photoelectric effect, Bragg reflection, and Compton scattering. Recent technological advances in high-spatial-resolution gas-filled X-ray detectors have enabled efficient polarimeters exploiting the photoelectric effect that hold great scientific promise for X-ray polarimetry in the 2-10 keV band. Advances in the fabrication of multilayer optics have made feasible the construction of broad-band soft X-ray polarimeters based on Bragg reflection. Developments in scintillator and solid-state hard X-ray detectors facilitate construction of both modular, large area Compton scattering polarimeters and compact devices suitable for use with focusing X-ray telescopes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.5899v3.pdf"}
{"id": "1408.6076", "abstract": "  The existence of dark matter provides compelling evidence for physics beyond the Standard Model. Minimal extensions of the Standard Model with additional scalars or fermions allow to explain the observed dark matter relic density in an economic way. We analyse several of these possibilities like the inert Higgs and radiative seesaw models in the light of the recent Higgs discovery and study prospects for the direct and indirect detection of dark matter in these models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.6076v1.pdf"}
{"id": "1408.6773", "abstract": "  We study analytically and by numerical simulations the statistics of the aftershocks generated after large avalanches in models of interface depinning that include viscoelastic relaxation effects. We find in all the analyzed cases that the decay law of aftershocks with time can be understood by considering the typical roughness of the interface and its evolution due to relaxation. In models where there is a single viscoelastic relaxation time there is an exponential decay of the number of aftershocks with time. In models in which viscoelastic relaxation is wave-vector dependent we typically find a power law dependence of the decay rate, compatible with the Omori law. The factors that determine the value of the decay exponent are analyzed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.6773v1.pdf"}
{"id": "1409.2303", "abstract": "  Compressive sensing (CS) is a new methodology to capture signals at lower rate than the Nyquist sampling rate when the signals are sparse or sparse in some domain. The performance of CS estimators is analyzed in this paper using tools from statistical mechanics, especially called replica method. This method has been used to analyze communication systems like Code Division Multiple Access (CDMA) and multiple input multi- ple output (MIMO) systems with large size. Replica analysis, now days rigorously proved, is an efficient tool to analyze large systems in general. Specifically, we analyze the performance of some of the estimators used in CS like LASSO (the Least Absolute Shrinkage and Selection Operator) estimator and Zero-Norm regularizing estimator as a special case of maximum a posteriori (MAP) estimator by using Bayesian framework to connect the CS estimators and replica method. We use both replica symmetric (RS) ansatz and one-step replica symmetry breaking (1RSB) ansatz, clamming the latter is efficient when the problem is not convex. This work is more analytical in its form. It is deferred for next step to focus on the numerical results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1409/1409.2303v1.pdf"}
{"id": "1409.4486", "abstract": "  It is proposed that planetesimals perturbed by Jovian mean-motion resonances are the source of shock waves that form chondrules. It is considered that this shock-induced chondrule formation requires the velocity of the planetesimal relative to the gas disk to be on the order of > 7 km/s at 1 AU. In previous studies on planetesimal excitation, the effects of Jovian mean-motion resonance together with the gas drag were investigated, but the velocities obtained were at most 8 km/s in the asteroid belt, which is insufficient to account for the ubiquitous existence of chondrules. In this paper, we reexamine the effect of Jovian resonances and take into account the secular resonance in the asteroid belt caused by the gravity of the gas disk. We find that the velocities relative to the gas disk of planetesimals a few hundred kilometers in size exceed 12 km/s, and that this is achieved around the 3:1 mean-motion resonance. The heating region is restricted to a relatively narrow band between 1.5 AU and 3.5 AU. Our results suggest that chondrules were produced effectively in the asteroid region after Jovian formation. We also find that many planetesimals are scattered far beyond Neptune. Our findings can explain the presence of crystalline silicate in comets if the scattered planetesimals include silicate dust processed by shock heating. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1409/1409.4486v1.pdf"}
{"id": "1409.6567", "abstract": "  Sky maps are powerful visualisation tools for quicklook analysis of extended sources. The latest sky map in soft X-rays (0.1-2.4 keV) has been created in 90ies using ROSAT data. By analyzing publically available data from XMM-Newton X-ray mission we constructed new sky maps in two energy bands – 2-5 keV and 5-10 keV, complementary to ROSAT data, covering about 1", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1409/1409.6567v1.pdf"}
{"id": "1409.7959", "abstract": "  Group-level behaviour of particles undergoing a velocity jump process with hard-sphere interactions is investigated. We derive N-particle transport equations that include the possibility of collisions between particles and apply different approximation techniques to get expressions for the dependence of the collective diffusion coefficient on the number of particles and their diameter. The derived approximations are compared with numerical results obtained from individual-based simulations. The theoretical results compare well with Monte Carlo simulations providing the excluded volume fraction is small. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1409/1409.7959v1.pdf"}
{"id": "1409.8312", "abstract": "  Finding an accurate ab initio approach for calculating the electronic properties of transition metal oxides has been a problem for several decades. In this paper, we investigate the electronic structure of the transition metal monoxides MnO, CoO, and NiO in their undistorted rock-salt structure within a fully iterated quasiparticle self-consistent GW (QPscGW) scheme. We study the convergence of the QPscGW method, i.e., how the quasiparticle energy eigenvalues and wavefunctions converge as a function of the QPscGW iterations, and we compare the converged outputs obtained from different starting wavefunctions. We find that the convergence is slow and that a one-shot G_0W_0 calculation does not significantly improve the initial eigenvalues and states. It is important to notice that in some cases the \"path\" to convergence may go through energy band reordering which cannot be captured by the simple initial unperturbed Hamiltonian. When we reach a fully iterated solution, the converged density of states, band-gaps and magnetic moments of these oxides are found to be only weakly dependent on the choice of the starting wavefunctions and in reasonably good agreement with the experiment. Finally, this approach provides a clear picture of the interplay between the various orbitals near the Fermi level of these simple transition metal monoxides. The results of these accurate ab initio calculations can provide input for models aiming at describing the low energy physics in these materials. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1409/1409.8312v2.pdf"}
{"id": "1410.1679", "abstract": "  Preliminary results from an ongoing project to compute a grid of post-AGB models is presented. Our preliminary results show that stellar evolution computations that include an updated treatment of the microphysics predict post-AGB timescales that are several times shorter that predicted by older models. Also the mass-luminosity relation of post-AGB models deviates from that of older grids. In addition, our results suggest only a slight metallicity dependence of the post-AGB timescales. We expect these results to have significant consequences for models of the formation of planetary nebulae and their luminosity function. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.1679v1.pdf"}
{"id": "1410.1978", "abstract": "  Dihadron correlations are measured in d+Au collisions at 200 GeV by the STAR detector. The correlated yields with uniform background subtraction are studied in high- and low-multiplicity collisions. The effects of multiplicity selection bias on jet-like correlations are discussed. Finite correlated yields are observed on the near-side at large pseudo-rapidity separation in high-multiplicity collisions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.1978v1.pdf"}
{"id": "1410.3536", "abstract": "  We report on recent progress in the evaluation of next-to-leading order observables using Lipatov's QCD high energy effective action. In this contribution we focus on the determination of the real part of the next-to-leading order corrections to the Mueller-Tang impact factor which is the only missing element for a complete NLO BFKL description of quark induced dijet events with a rapidity gap. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.3536v1.pdf"}
{"id": "1410.3580", "abstract": "  In a previous publication, we discussed the formalism and some computational results for phononic thermal conduction in the suspended membrane geometry for radial heat flow from a central source, which is a common geometry for some low-temperature detectors, for example. We studied the case where only diffusive surface scattering is present, the so called Casimir limit, which can be experimentally relevant at temperatures below ∼ 10 K in typical materials, and even higher for ultrathin samples. Here, we extend our studies to much thinner membranes, obtaining numerical results for geometries which are more typical in experiments. In addition, we interpret the results in terms of a small signal and differential thermal conductance, so that guidelines for designing devices, such as low-temperature bolometric detectors, are more easily obtained. Scaling with membrane dimensions is shown to differ significantly from the bulk scattering, and, in particular, thinning the membrane is shown to lead to a much stronger reduction in thermal conductance than what one would envision from the simplest bulk formulas. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.3580v1.pdf"}
{"id": "1410.3884", "abstract": "  The correlations between multiplicities in two separated rapidity windows, is studied in the framework of the Monte Carlo model based on the picture of string formation in elementary collisions of colour dipoles. The hardness of the elementary collisions is defined by a transverse size of the interacting dipoles. The dependencies of the forward-backward correlation strength on the width and position of the pseudorapidity windows, as well as on transverse momentum range of observed particles were studied. It is demonstrated that taking into account of the string fusion effects improves the agreement with the available experimental data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.3884v1.pdf"}
{"id": "1410.5459", "abstract": "  A central issue of the science of complex systems is the quantitative characterization of complexity. In the present work we address this issue by resorting to information geometry. Actually we propose a constructive way to associate to a - in principle any - network a differentiable object (a Riemannian manifold) whose volume is used to define an entropy. The effectiveness of the latter to measure networks complexity is successfully proved through its capability of detecting a classical phase transition occurring in both random graphs and scale–free networks, as well as of characterizing small Exponential random graphs, Configuration Models and real networks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.5459v5.pdf"}
{"id": "1410.6004", "abstract": "  We study the mutual interaction between two identical quantum dots coupled to the normal modes of two-site photonic crystal molecules in a planar waveguide geometry, i.e. photonic crystal dimers. We find that the radiative coupling between the two quantum emitters is maximized when they are in resonance with either the bonding or the antibonding modes of the coupled cavity system. Moreover, we find that such effective interdot coupling is sizable, in the meV range, and almost independent from the cavities distance, as long as a normal mode splitting exceeding the radiative linewidth can be established (strong cavity-cavity coupling condition). In realistic and high quality factor photonic crystal cavity devices, such distance can largely exceed the emission wavelength, which is promising for long distance entanglement generation between two qubits in an integrated nanophotonic platform. We show that these results are robust against position disorder of the two quantum emitters within their respective cavities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.6004v1.pdf"}
{"id": "1410.6653", "abstract": "  One possible origin for polarization structures across jets of Active Galactic Nuclei (AGNs) with a central \"spine\" of orthogonal magnetic field and a \"sheath\" of longitudinal magnetic field along one or both edges of the jet is the presence of a helical jet magnetic field. Simultaneous Very Long Baseline Array (VLBA) polarization observations of AGN displaying partial or full spine–sheath polarization structures were obtained at 4.6, 5.0, 7.9, 8.9, 12.9 and 15.4 GHz, in order to search for additional evidence for helical jet magnetic fields, such as transverse Faraday rotation gradients (due to the systematic change in the line-of-sight magnetic-field component across the jet). Results for eight sources displaying monotonic transverse Faraday rotation gradients with significances ≥ 3σ are presented here. Reversals in the directions of the transverse RM gradients with distance from the core or with time are detected in three of these AGNs. These can be interpreted as evidence for a nested helical magnetic field structure, with different directions for the azimuthal field component in the inner and outer regions of helical field. The results presented here support the idea that many spine–sheath polarization structures reflect the presence of helical magnetic fields being carried by these jets. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.6653v2.pdf"}
{"id": "1410.6823", "abstract": "  We propose a scheme to generate entanglement between a single-photon qubit in the polarization basis and a coherent state of light. The required resources are a superposition of coherent states, a polarization entangled photon pair, beam splitters, the displacement operation, and four photodetectors. Even when realistic detectors with a limited efficiency are used, an arbitrarily high fidelity can be obtained by adjusting a beam-splitter ratio and the displacement amplitude at the price of reducing the success probability. Our analysis shows that high fidelities may be obtained using on-off detectors with low efficiencies and available resource states under current technology. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.6823v3.pdf"}
{"id": "1410.8763", "abstract": "  Using large-scale kinetic Monte-Carlo (KMC) simulations, we investigate the non-equilibrium surface growth of the fullerene C_60. Recently, we have presented a self-consistent set of energy barriers that describes the nucleation and multilayer growth of C_60 for different temperatures and adsorption rates in quantitative agreement with experiments [Bommel et al., Nat. Comm. 5, 5388 (2014)]. We found that C_60 displays lateral diffusion resembling colloidal systems, however it has to overcome an atom-like energetic step-edge barrier for interlayer diffusion. Here, we focus on the particle-resolved dynamics, and the interplay between surface morphology and particle dynamics during growth. Comparing C_60 growth with an atom-like system, we find significant differences in the evolution of the surface morphology, as well as the single-particle dynamics on the growing material landscape. By correlating the mean-squared-displacement of particles with their current neighborhood, we can identify the influence of the different time scales that compete during growth and can pinpoint the differences between the two systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.8763v2.pdf"}
{"id": "1411.0585", "abstract": "  Many charmonium-like and bottomonium-like XYZ resonances have been observed by the Belle, Babar, CLEO and BESIII collaborations in the past decade. They are difficult to fit in the conventional quark model and thus are considered as candidates of exotic hadrons, such as multi-quark states, meson molecules, and hybrids. In this talk, we first briefly introduce the method of QCD sum rules and then provide a short review of the mass spectra of the quarkonium-like tetraquark states and the heavy quarkonium hybrids in the QCD sum rules approach. Possible interpretations of the XYZ resonances are briefly discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1411/1411.0585v1.pdf"}
{"id": "1411.2490", "abstract": "  Parker has hypothesised that, in a perfectly ideal environment, complex photospheric motions acting on a continuous magnetic field will result in the formation of tangential discontinuities corresponding to singular currents. We review direct numerical simulations of the problem and find the evidence points to a tendency for thin but finite thickness current layers to form, with thickness exponentially decreasing in time. Given a finite resistivity these layers will eventually become important and cause the dynamical process of energy release. Accordingly, a body of work focusses on evolution under continual boundary driving. The coronal volume evolves into a highly dynamic but statistically steady state where quantities have a temporally and spatially intermittent nature and where the Poynting flux and dissipation are decoupled on short timescales. Although magnetic braiding is found to be a promising coronal heating mechanism much work remains to determine its true viability. Some suggestions for future study are offered. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1411/1411.2490v1.pdf"}
{"id": "1411.2572", "abstract": "  In the paper we numerically study positions of high spots (extrema) of the fundamental sloshing mode of liquid in an axisymmetric tank. Our approach is based on a linear model reducing the problem to appropriate Steklov eigenvalue problem. We propose a numerical scheme for calculating sloshing modes and a novel method of making images of oscillating fluid. We also describe the relation of the high spot problem to the celebrated hot spots conjecture. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1411/1411.2572v1.pdf"}
{"id": "1411.2814", "abstract": "  The gauge invariant non local quantum dynamics of the Aharonov-Bohm effect can be tested experimentally by measuring the instantaneous shift of the velocity distribution occurring when the particle passes by the flux line. It is shown that in relativistic quantum theory it is possible to measure the instantaneous velocity with accuracy sufficient to detect the change of the velocity distribution. In non relativistic quantum theory the instantaneous velocity can be measured to any desired accuracy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1411/1411.2814v2.pdf"}
{"id": "1411.2875", "abstract": "  We propose a discrete transition-based reweighting analysis method (dTRAM) for analyzing configuration-space-discretized simulation trajectories produced at different thermodynamic states (temperatures, Hamiltonians, etc.) dTRAM provides maximum-likelihood estimates of stationary quantities (probabilities, free energies, expectation values) at any thermodynamic state. In contrast to the weighted histogram analysis method (WHAM), dTRAM does not require data to be sampled from global equilibrium, and can thus produce superior estimates for enhanced sampling data such as parallel/simulated tempering, replica exchange, umbrella sampling, or metadynamics. In addition, dTRAM provides optimal estimates of Markov state models (MSMs) from the discretized state-space trajectories at all thermodynamic states. Under suitable conditions, these MSMs can be used to calculate kinetic quantities (e.g. rates, timescales). In the limit of a single thermodynamic state, dTRAM estimates a maximum likelihood reversible MSM, while in the limit of uncorrelated sampling data, dTRAM is identical to WHAM. dTRAM is thus a generalization to both estimators. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1411/1411.2875v2.pdf"}
{"id": "1411.4701", "abstract": "  We propose a vision-based highway border detection algorithm using structured Hough voting. Our approach takes advantage of the geometric relationship between highway road borders and highway lane markings. It uses a strategy where a number of trained road border and lane marking detectors are triggered, followed by Hough voting to generate corresponding detection of the border and lane marking. Since the initially triggered detectors usually result in large number of positives, conventional frame-wise Hough voting is not able to always generate robust border and lane marking results. Therefore, we formulate this problem as a joint detection-and-tracking problem under the structured Hough voting model, where tracking refers to exploiting inter-frame structural information to stabilize the detection results. Both qualitative and quantitative evaluations show the superiority of the proposed structured Hough voting model over a number of baseline methods. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1411/1411.4701v1.pdf"}
{"id": "1411.6646", "abstract": "  We introduce session automata, an automata model to process data words, i.e., words over an infinite alphabet. Session automata support the notion of fresh data values, which are well suited for modeling protocols in which sessions using fresh values are of major interest, like in security protocols or ad-hoc networks. Session automata have an expressiveness partly extending, partly reducing that of classical register automata. We show that, unlike register automata and their various extensions, session automata are robust: They (i) are closed under intersection, union, and (resource-sensitive) complementation, (ii) admit a symbolic regular representation, (iii) have a decidable inclusion problem (unlike register automata), and (iv) enjoy logical characterizations. Using these results, we establish a learning algorithm to infer session automata through membership and equivalence queries. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1411/1411.6646v2.pdf"}
{"id": "1412.1824", "abstract": "  We investigate new and archival 3-5 μm high resolution (∼3 km s^-1) spectroscopy of molecular gas in the inner disk of the young solar-mass star EX Lupi, taken during and after the strong accretion outburst of 2008. The data were obtained using the CRIRES spectrometer at the ESO Very Large Telescope in 2008 and 2014. In 2008, emission lines from CO, H_2O, and OH were detected with broad profiles tracing gas near and within the corotation radius (0.02-0.3 AU). In 2014, the spectra display marked differences. The CO lines, while still detected, are much weaker, and the H_2O and OH lines have disappeared altogether. At 3 μm a veiled stellar photospheric spectrum is observed. Our analysis finds that the molecular gas mass in the inner disk has decreased by an order of magnitude since the outburst, matching a similar decrease in the accretion rate onto the star. We discuss these findings in the context of a rapid depletion of material accumulated beyond the disk corotation radius during quiescent periods, as proposed by models of episodic accretion in EXor type young stars. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.1824v1.pdf"}
{"id": "1412.2551", "abstract": "  Complex plasmas are low-temperature plasmas that contain micrometer-size particles in addition to the neutral gas particles and the ions and electrons that make up the plasma. The microparticles interact strongly and display a wealth of collective effects. Here we report on linked numerical simulations that reproduce many of the experimental results of complex plasmas. We model a capacitively coupled plasma with a fluid code written for the commercial package comsol. The output of this model is used to calculate forces on microparticles. The microparticles are modeled using the molecular dynamics package lammps, which we extended to include the forces from the plasma. Using this method, we are able to reproduce void formation, the separation of particles of different sizes into layers, lane formation, vortex formation, and other effects. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.2551v1.pdf"}
{"id": "1412.3783", "abstract": "  We investigate in details the inertial dynamics of a uniform magnetization in the ferromagnetic resonance (FMR) context. Analytical predictions and numerical simulations of the complete equations within the Inertial Landau-Lifshitz-Gilbert (ILLG) model are presented. In addition to the usual precession resonance, the inertial model gives a second resonance peak associated to the nutation dynamics provided that the damping is not too large. The analytical resolution of the equations of motion yields both the precession and nutation angular frequencies. They are function of the inertial dynamics characteristic time τ, the dimensionless damping α and the static magnetic field H. A scaling function with respect to ατγ H is found for the nutation angular frequency, also valid for the precession angular frequency when ατγ H≫ 1. Beyond the direct measurement of the nutation resonance peak, we show that the inertial dynamics of the magnetization has measurable effects on both the width and the angular frequency of the precession resonance peak when varying the applied static field. These predictions could be used to experimentally identify the inertial dynamics of the magnetization proposed in the ILLG model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.3783v1.pdf"}
{"id": "1412.3858", "abstract": "  We consider the motion of light on different spacetime manifolds by calculating the deflection angle, lensing properties and by probing into the possibility of bound states. The metrics in which we examine the light motion include, among other, a general relativistic Dark Matter metric, a dirty Black Hole and a Worm Hole metric, the last two inspired by non-commutative geometry. The lensing in a Holographic Screen metric is discussed in detail. We study also the bending of light around naked singularities like, e.g., the Janis-Newman-Winicour metric and include other cases. A generic property of light behaviour in these exotic metrics is pointed out. For the standard metric like the Schwarzschild and Schwarzschild-de Sitter cases we improve the accuracy of the lensing results for the weak and strong regime. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.3858v1.pdf"}
{"id": "1412.3965", "abstract": "  We study theoretically the effects of strong pinning centers on a charge density wave in the limit that the charge density wave coherence length is shorter than the average inter-impurity distance. An analysis based on a Ginzburg-Landau model shows that long range forces arising from the elastic response of the charge density wave induce a kind of collective pinning which suppresses impurity-induced phase fluctuations leading to a long ranged ordered ground state. The effective correlations among impurities are characterized by a length scale parametrically longer than the average inter-impurity distance. The thermal excitations are found to be gapped implying the stability of the ground state. We also present Monte Carlo simulations that confirm the basic features of the analytical results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.3965v1.pdf"}
{"id": "1412.4337", "abstract": "  A new family of 2D discrete-time quantum walks (DTQWs) is presented and shown to coincide, in the continuous limit, with the Dirac dynamics of a spin 1/2 fermion coupled to a constant and uniform magnetic field. Landau levels are constructed, not only in the continuous limit, but also for the DTQWs i.e. for finite non-vanishing values of the time- and position-step, by a perturbative approach in the step. Numerical simulations support the above results and suggest that the magnetic interpretation is valid beyond the scope of the continuous limit. The possibility of quantum simulation of condensed-matter systems by DTQWs is also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.4337v2.pdf"}
{"id": "1412.5035", "abstract": "  The strength of the nonlinearity is measured in decaying two-dimensional turbulence, by comparing its value to that found in a Gaussian field. It is shown how the nonlinearity drops following a two-step process. First a fast relaxation is observed on a timescale comparable to the time of for-mation of vortical structures, then at long times the nonlinearity relaxes further during the phase when the eddies merge to form the final dynamic state of decay. Both processes seem roughly independent of the value of the Reynolds number. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.5035v1.pdf"}
{"id": "1412.8140", "abstract": "  We perform a detailed physical analysis for a class of exact solutions for the Einstein-Maxwell equations. The linear equation of state consistent with quark stars has been incorporated in the model. The physical analysis of the exact solutions is performed by considering the charged anisotropic stars for the particular nonsingular exact model obtained by Maharaj, Sunzu and Ray. In performing such an analysis we regain masses obtained by previous researchers for isotropic and anisotropic matter. It is also indicated that other masses and radii may be generated which are in acceptable ranges consistent with observed values of stellar objects. A study of the mass-radius relation indicates the effect of the electromagnetic field and anisotropy on the mass of the relativistic star. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.8140v1.pdf"}
{"id": "1501.01315", "abstract": "  We explore the dynamics of the entanglement entropy near equilibrium in highly-entangled pure states of two quantum-chaotic spin chains undergoing unitary time evolution. We examine the relaxation to equilibrium from initial states with either less or more entanglement entropy than the equilibrium value, as well as the dynamics of the spontaneous fluctuations of the entanglement that occur in equilibrium. For the spin chain with a time-independent Hamiltonian and thus an extensive conserved energy, we find slow relaxation of the entanglement entropy near equilibration. Such slow relaxation is absent in a Floquet spin chain with a Hamiltonian that is periodic in time and thus has no local conservation law. Therefore, we argue that slow diffusive energy transport is responsible for the slow relaxation of the entanglement entropy in the Hamiltonian system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.01315v4.pdf"}
{"id": "1501.01672", "abstract": "  We demonstrate that the transport characteristics of deep optical lattices with one or multiple off-resonant external energy offsets can be greatly-enhanced by modulating the lattice depth in an exotic way. We derive effective stationary models for our proposed modulation schemes in the strongly interacting limit, where only one particle can occupy any given site. Afterwards we discuss the modifications necessary to recover transport when more than one particle may occupy the lattice sites. For the specific five-site lattices discussed, we numerically predict transport gains for ranging from 4.7× 10^6 to 9.8× 10^8. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.01672v2.pdf"}
{"id": "1501.01823", "abstract": "  We studied the properties of the low-frequency quasi-periodic oscillations detected in a sample of six black hole candidates (XTE J1550-564, H 1743-322, XTE J1859+226, 4U 1630-47,GX 339-4, XTE J1650-500) observed by the Rossi XTE satellite. We analyzed the relation between the full width half maximum and the frequency of all the narrow peaks detected in power density spectra where a type-C QPO is observed. Our goal was to understand the nature of the modulation of the signal by comparing the properties of different harmonic peaks in the power density spectrum. We find that for the sources in our sample the width of the fundamental and of the first harmonic are compatible with a frequency modulation, while that of the sub-harmonic is independent of frequency, possibly indicating the presence of an additional modulation in amplitude. We compare our results with those obtained earlier from GRS 1915+105 and XTE J1550-564. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.01823v1.pdf"}
{"id": "1501.03879", "abstract": "  The Euclidean Median (EM) of a set of points Ω in an Euclidean space is the point x minimizing the (weighted) sum of the Euclidean distances of x to the points in Ω. While there exits no closed-form expression for the EM, it can nevertheless be computed using iterative methods such as the Wieszfeld algorithm. The EM has classically been used as a robust estimator of centrality for multivariate data. It was recently demonstrated that the EM can be used to perform robust patch-based denoising of images by generalizing the popular Non-Local Means algorithm. In this paper, we propose a novel algorithm for computing the EM (and its box-constrained counterpart) using variable splitting and the method of augmented Lagrangian. The attractive feature of this approach is that the subproblems involved in the ADMM-based optimization of the augmented Lagrangian can be resolved using simple closed-form projections. The proposed ADMM solver is used for robust patch-based image denoising and is shown to exhibit faster convergence compared to an existing solver. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.03879v1.pdf"}
{"id": "1501.05382", "abstract": "  Mixture of parts model has been successfully applied to 2D human pose estimation problem either as explicitly trained body part model or as latent variables for the whole human body model. Mixture of parts model usually utilize tree structure for representing relations between body parts. Tree structures facilitate training and referencing of the model but could not deal with double counting problems, which hinder its applications in 3D pose estimation. While most of work targeted to solve these problems tend to modify the tree models or the optimization target. We incorporate other cues from input features. For example, in surveillance environments, human silhouettes can be extracted relative easily although not flawlessly. In this condition, we can combine extracted human blobs with histogram of gradient feature, which is commonly used in mixture of parts model for training body part templates. The method can be easily extend to other candidate features under our generalized framework. We show 2D body part detection results on a public available dataset: HumanEva dataset. Furthermore, a 2D to 3D pose estimator is trained with Gaussian process regression model and 2D body part detections from the proposed method is fed to the estimator, thus 3D poses are predictable given new 2D body part detections. We also show results of 3D pose estimation on HumanEva dataset. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.05382v2.pdf"}
{"id": "1502.00002", "abstract": "  Spontaneous breaking of translational symmetry—known as `density wave' order—is common in nature. However such states are strongly sensitive to impurities or other forms of frozen disorder leading to fascinating glassy phenomena. We analyze impurity effects on a particularly ubiquitous form of broken translation symmetry in solids: a Spin Density Wave (SDW) with spatially modulated magnetic order. Related phenomena occur in Pair Density Wave (PDW) superconductors where the superconducting order is spatially modulated. For weak disorder, we find that the SDW / PDW order can generically give way to a SDW / PDW glass—new phases of matter with a number of striking properties, which we introduce and characterize here. In particular, they exhibit an interesting combination of conventional (symmetry-breaking) and spin glass (Edwards-Anderson) order. This is reflected in the dynamic response of such a system, which—as expected for a glass—is extremely slow in certain variables, but—surprisingly—is fast in others. Our results apply to all uniaxial metallic SDW systems where the ordering vector is incommensurate with the crystalline lattice. In addition, the possibility of a PDW glass has important consequences for some recent theoretical and experimental work on La_2-xBa_xCu_2O_4. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.00002v1.pdf"}
{"id": "1502.01200", "abstract": "  A recently published correlated electron pseudopotentials (CEPPs) method has been adapted for application to the 3d-transition metals, and to include relativistic effects. New CEPPs are reported for the atoms Sc-Fe, constructed from atomic quantum chemical calculations that include an accurate description of correlated electrons. Dissociation energies, molecular geometries, and zero-point vibrational energies of small molecules are compared with all electron results, with all quantities evaluated using coupled cluster singles doubles and triples (CCSD(T)) calculations. The CEPPs give better results in the correlated-electron calculations than Hartree-Fock-based pseudopotentials available in the literature. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.01200v1.pdf"}
{"id": "1502.03015", "abstract": "  One of the most important problem of the blazar astrophysics is to understand the physical origin of the blazar sequence. In this study, we focus on the GeV gamma-ray variability of blazars and evolution perspective we search the relation between the redshift and the variability amplitude of blazars for each blazar subclass. We analyzed the Fermi-LAT data of the TeV blazars and the bright AGNs (flux ≥ 4×10^-9 cm^-2s^-1) selected from the 2LAC (the 2nd LAT AGN catalog) data base. As a result, we found a hint of the correlation between the redshift and the variability amplitude in the FSRQs. Furthermore the BL Lacs which have relatively lower peak frequency of the synchrotron radiation and relatively lower redshift, have a tendency to have a smaller variability amplitude. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.03015v1.pdf"}
{"id": "1502.03643", "abstract": "  The Sun and the undisturbed interstellar magnetic field and plasma velocity vectors (Bis,Vis) define a mirror symmetry plane of the flow at large heliospheric distances. We show that for the Bis direction defined by IBEX Ribbon center, the radial direction of Voyager 2 over the last decade, and the (thermal proton) plasma velocity measured by the spacecraft since 2010.5, are almost parallel to the (Bis,Vis)-plane, which coincides in practice with the Hydrogen Deflection Plane. These facts can be simply explained if approximate mirror symmetry is also maintained on the inner side of the heliopause. Such approximate symmetry is possible since the solar wind ram pressure is almost spherically symmetric and the plasma beta value in the inner heliosheath is high. In the proposed symmetry, the plasma flow speed measured by Voyager 2 in the inner heliosheath is expected to rotate more in the transverse than in the polar direction (explanation alternative to McComas     Schwadron (2014)), in evident agreement with available spacecraft data (our Fig.1). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.03643v1.pdf"}
{"id": "1502.04255", "abstract": "  Despite decades of intense efforts, many fundamental aspects of Type Ia supernova (SNe Ia) remain elusive. One of the major open questions is whether the mass of the exploding white dwarf (WD) is close to the Chandrasekhar limit. Here we report the detection of strong K-shell emission from stable Fe-peak elements in the Suzaku X-ray spectrum of the Type Ia supernova remnant (SNR) 3C 397. The high Ni/Fe and Mn/Fe mass ratios (0.11-0.24 and 0.018-0.033, respectively) in the hot plasma component that dominates the K-shell emission lines indicate a degree of neutronization in the SN ejecta which can only be achieved by electron captures in the dense cores of exploding WDs with a near-Chandrasekhar mass. This suggests a single-degenerate origin for 3C 397, since Chandrasekhar mass progenitors are expected naturally if the WD accretes mass slowly from a companion. Together with other results supporting the double-degenerate scenario, our work adds to the mounting evidence that both progenitor channels make a significant contribution to the SN Ia rate in star-forming galaxies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.04255v1.pdf"}
{"id": "1502.05265", "abstract": "  It is widely accepted that the Poisson-Boltzmann (PB) theory provides a valid description for charged surfaces in the so-called weak coupling limit. Here, we show that the image charge repulsion creates a depletion boundary layer that cannot be captured by a regular perturbation approach. The correct weak-coupling theory must include the self-energy of the ion due to the image charge interaction. The image force qualitatively alters the double layer structure and properties, and gives rise to many non-PB effects, such as nonmonotonic dependence of the surface energy on concentration and charge inversion. In the presence of dielectric discontinuity, there is no limiting condition for which the PB theory is valid. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.05265v1.pdf"}
{"id": "1502.05819", "abstract": "  We present an implementation of the Galerkin-Collocation method to determine the initial data for non-rotating distorted three dimensional black holes in the inversion and puncture schemes. The numerical method combines the key features of the Galerkin and Collocation methods which produces accurate initial data. We evaluated the ADM mass of the initial data sets, and we have provided the angular structure of the gravitational wave distribution at the initial hypersurface by evaluating the scalar Ψ_4 for asymptotic observers. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.05819v1.pdf"}
{"id": "1503.01232", "abstract": "  This work presents a general unifying theoretical framework for quantum non-equilibrium systems. It is based on a re-statement of the dynamical problem as one of inferring the distribution of collision events that move a system toward thermal equilibrium from an arbitrary starting distribution. Using a form based on maximum entropy for this transition distribution leads to a statistical description of open quantum systems with strong parallels to the conventional, maximum-entropy, equilibrium thermostatics. A precise form of the second law of thermodynamics can be stated for this dynamics at every time-point in a trajectory. Numerical results are presented for low-dimensional systems interacting with cavity fields. The dynamics and stationary state are compared to a reference model of a weakly coupled oscillator plus cavity supersystem thermostatted by periodic partial measurements. Despite the absence of an explicit cavity in the present model of open quantum dynamics, both the relaxation rates and stationary state properties closely match the reference. Additionally, the time-course of energy exchange and entropy increase is given throughout an entire measurement process for a single spin system. The results show the process to be capable of initially absorbing heat when starting from a superposition state, but not from an isotropic distribution. Based on these results, it is argued that logical inference in the presence of environmental noise is sufficient to resolve the paradox of wavefunction collapse. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.01232v2.pdf"}
{"id": "1503.02247", "abstract": "  A set of analytical benchmarks for tracking programs is required for precision storage ring experiments. To determine the accuracy of precision tracking programs in electric and magnetic rings, a variety of analytical estimates of particle and spin dynamics in the rings were developed and compared to the numerical results of tracking simulations. Initial discrepancies in the comparisons indicated the need for improvement of several of the analytical estimates. As an example, we found that the fourth-order Runge-Kutta/Predictor-Corrector method was slow but accurate, and that it passed all the benchmarks it was tested against, often to the sub-part per billion level. Thus, high precision analytical estimates and tracking programs based on fourth-order Runge-Kutta/Predictor-Corrector integration can be used to benchmark faster tracking programs for accuracy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.02247v2.pdf"}
{"id": "1503.02614", "abstract": "  The ESA Gaia mission uses two telescopes to create the most ambitious survey of the Galaxy. The angle between them must be known with exquisite precision and accuracy. An interferometer: the Basic Angle Monitoring system measures its variations. High quality data have been retrieved and analysed for more than a year. A summary of the in-orbit performance and some early results are presented ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.02614v1.pdf"}
{"id": "1503.05169", "abstract": "  It is proposed to produce highly charged ions in the local potential traps formed by the rippled electron beam in a focusing magnetic field. In this method, the extremely high electron current densities can be attained on short length of the ion trap. The design the very compact ion sources is feasible. For such ions as, for example, Ne^8+ and Xe^44+, the intensities of about 10^9 and 10^6 particles per second, respectively, can be obtained. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.05169v1.pdf"}
{"id": "1504.00132", "abstract": "  The new muon (g-2) experiment E989 at Fermilab will be equipped with a laser calibration system for all the 1296 channels of the calorimeters. An integrating sphere and an alternative system based on an engineered diffuser have been considered as possible light distributors for the experiment. We present here a detailed comparison of the two based on temporal response, spatial uniformity, transmittance and time stability. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.00132v1.pdf"}
{"id": "1504.00139", "abstract": "  In open system approaches with non-Markovian environments, the process of inserting an individual mode (denoted as \"pseudomode\") into the bath or extracting it from the bath is widely employed. This procedure, however, is typically performed on basis of the spectral density (SD) and does not incorporate temperature. Here, we show how the - temperature-dependent - bath correlation function (BCF) transforms in such a process. We present analytic formulae for the transformed BCF and numerically study the differences between factorizing initial state and global thermal (correlated) initial state of mode and bath, respectively. We find that in the regime of strong coupling of the mode to both system and bath, the differences in the BCFs give rise to pronounced differences in the dynamics of the system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.00139v2.pdf"}
{"id": "1504.02034", "abstract": "  We present a Monte Carlo model for degradation of 1-10,000 eV electrons in an atmosphere of methane. The electron impact cross sections for CH4 are compiled and analytical representations of these cross sections are used as input to the model.model.Yield spectra, which provides information about the number of inelastic events that have taken place in each energy bin, is used to calculate the yield (or population) of various inelastic processes. The numerical yield spectra, obtained from the Monte Carlo simulations, is represented analytically, thus generating the Analytical Yield Spectra (AYS). AYS is employed to obtain the mean energy per ion pair and efficiencies of various inelastic processes.Mean energy per ion pair for neutral CH4 is found to be 26 (27.8) eV at 10 (0.1) keV. Efficiency calculation showed that ionization is the dominant process at energies >50 eV, for which more than 50", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.02034v1.pdf"}
{"id": "1504.02840", "abstract": "  Image features detection and description is a longstanding topic in computer vision and pattern recognition areas. The Scale Invariant Feature Transform (SIFT) is probably the most popular and widely demanded feature descriptor which facilitates a variety of computer vision applications such as image registration, object tracking, image forgery detection, and 3D surface reconstruction. This work introduces a Software as a Service (SaaS) based implementation of the SIFT algorithm which is freely available at http://siftservice.com for any academic, educational and research purposes. The service provides application-to-application interaction and aims Rapid Application Development (RAD) and also fast prototyping for computer vision students and researchers all around the world. An Internet connection is all they need! ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.02840v1.pdf"}
{"id": "1504.03232", "abstract": "  Statistical evaluations of the economic mobility of a society are more difficult than measurements of the income distribution, because they require to follow the evolution of the individuals' income for at least one or two generations. In micro-to-macro theoretical models of economic exchanges based on kinetic equations, the income distribution depends only on the asymptotic equilibrium solutions, while mobility estimates also involve the detailed structure of the transition probabilities of the model, and are thus an important tool for assessing its validity. Empirical data show a remarkably general negative correlation between economic inequality and mobility, whose explanation is still unclear. It is therefore particularly interesting to study this correlation in analytical models. In previous work we investigated the behavior of the Gini inequality index in kinetic models in dependence on several parameters which define the binary interactions and the taxation and redistribution processes: saving propensity, taxation rates gap, tax evasion rate, welfare means-testing etc. Here, we check the correlation of mobility with inequality by analyzing the mobility dependence from the same parameters. According to several numerical solutions, the correlation is confirmed to be negative. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.03232v1.pdf"}
{"id": "1504.03888", "abstract": "  We theoretically study effects of surface roughness on the magnetic response of small unconventional superconductors by solving the Eilenberger equation for the quassiclassical Green function and the Maxwell equation for the vector potential simultaneously and self-consistently. The paramagnetic phase of spin-singlet d-wave superconducting disks is drastically suppressed by the surface roughness, whereas that of spin-triplet p-wave disks is robust even in the presence of the roughness. Such difference derives from the orbital symmetry of paramagnetic odd-frequency Cooper pairs appearing at the surface of disks. The orbital part of the paramagnetic pairing correlation is p-wave symmetry in the d-wave disks, whereas it is s-wave symmetry in the p-wave ones. Calculating the free-energy, we also confirm that the paramagnetic state is more stable than the normal state, which indicates a possibility of detecting the paramagnetic effect in experiments. Indeed our results are consistent with an experimental finding on high-T_c thin films. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.03888v2.pdf"}
{"id": "1504.08234", "abstract": "  Separate spin evolution quantum hydrodynamics is generalized to include the Coulomb exchange interaction. The Coulomb exchange interaction is considered as the interaction between the spin-down electrons being in the quantum states occupied by one electron, giving main contribution in the equilibrium. The generalized model is applied to study the non-linear spin-electron acoustic waves. Existence of the spin-electron acoustic soliton is demonstrated. Contributions of the concentration, spin polarization, and exchange interaction in the properties of the spin electron acoustic soliton are studied. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.08234v2.pdf"}
{"id": "1504.08303", "abstract": "  We present, characterize, and apply a photonic quantum interface between the near infrared and telecom spectral regions. A singly resonant optical parametric oscillator (OPO) operated below threshold, in combination with external filters, generates high-rate (>2.5·10^6  s^-1) narrowband photon pairs (∼ 7 MHz bandwidth); the signal photons are tuned to resonance with an atomic transition in Ca^+, while the idler photons are at telecom wavelength. Quantum interface operation is demonstrated through high-rate absorption of single photons by a single trapped ion (∼ 670  s^-1), heralded by coincident telecom photons. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.08303v1.pdf"}
{"id": "1505.02469", "abstract": "  Social influence is ubiquitous in cultural markets, from book recommendations in Amazon, to song popularities in iTunes and the ranking of newspaper articles in the online edition of the New York Times to mention only a few. Yet social influence is often presented in a bad light, often because it supposedly increases market unpredictability.   Here we study a model of trial-offer markets, in which participants try products and later decide whether to purchase. We consider a simple policy which ranks the products by quality when presenting them to market participants. We show that, in this setting, market efficiency always benefits from social influence. Moreover, we prove that the market converges almost surely to a monopoly for the product of highest quality, making the market both predictable and asymptotically optimal. Computational experiments confirm that the quality ranking policy identifies \"blockbusters\" in reasonable time, outperforms other policies, and is highly predictable. These results indicate that social influence does not necessarily increase market unpredicatibility. The outcome really depends on how social influence is used. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.02469v3.pdf"}
{"id": "1505.02835", "abstract": "  We present upper bounds for the numerical errors introduced when using operator splitting methods to integrate transport and non-linear chemistry processes in global chemical transport models (CTM). We show that (a) operator splitting strategies that evaluate the stiff non-linear chemistry operator at the end of the time step are more accurate, and (b) the results of numerical simulations that use different operator splitting strategies differ by at most 10 percent, in a prototype one-dimensional non-linear chemistry-transport model. We find similar upper bounds in operator splitting numerical errors in global CTM simulations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.02835v2.pdf"}
{"id": "1505.04140", "abstract": "  A new Efficient-bandwidth code-division-multiple-access (CDMA) for band-limited channels is introduced which is based on finite field transforms. A multilevel code division multiplex exploits orthogonality properties of nonbinary sequences defined over a complex finite field. Galois-Fourier transforms contain some redundancy and just cyclotomic coefficients are needed to be transmitted yielding compact spectrum requirements. The primary advantage of such schemes regarding classical multiplex is their better spectral efficiency. This paper estimates the bandwidth compactness factor relatively to Time Division Multiple Access TDMA showing that it strongly depends on the alphabet extension. These multiplex schemes termed Galois Division Multiplex (GDM) are based on transforms for which there exists fast algorithms. They are also convenient from the implementation viewpoint since they can be implemented by a Digital Signal Processor. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.04140v1.pdf"}
{"id": "1505.04389", "abstract": "  In this paper we investigate dynamics of church bells, characterize their most common working regimes and investigate how to obtain them. To simulate the behavior of the yoke-bell-clapper system we use experimentally validated hybrid dynamical model developed basing on the detailed measurements of the biggest bell in the Cathedral Basilica of St Stanislaus Kostka, Lodz, Poland. We introduce two parameters that describes the yoke design and the propulsion mechanism and analyze their influence on the systems' dynamics. We develop two-parameter diagrams that allow to asses conditions that ensures proper and smooth operation of the bell. Similar charts can be calculated for any existing or non-existing bell and used when designing its mounting and propulsion. Moreover, we propose simple and universal launching procedure that allows to decrease the time that is needed to reach given attractor. Presented results are robust and indicate methods to increase the chance that the instrument will operate properly and reliably regardless of changes in working conditions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.04389v1.pdf"}
{"id": "1505.05843", "abstract": "  Abundances of Fe, Si, Ni, Ti, Na, Mg, Cu, Zn, Mn, Cr and Ca in the atmosphere of the K-dwarf HD 77338 are determined and discussed. HD 77338 hosts a hot Uranus-like planet and is currently the most metal-rich single star to host any planet. Determination of abundances was carried out in the framework of a self-consistent approach developed by Pavlenko et al. (2012). Abundances were computed iteratively by the program ABEL8, and the process converged after 4 iterations. We find that most elements follow the iron abundance, however some of the iron peak elements are found to be over-abundant in this star. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.05843v1.pdf"}
{"id": "1505.06286", "abstract": "  Recently the influence maximization problem has received much attention for its applications on viral marketing and product promotions. However, such influence maximization problems have not taken into account the monetary effect on the purchasing decision of individuals. To fulfill this gap, in this paper, we aim for maximizing the revenue by considering the quantity constraint on the promoted commodity. For this problem, we not only identify a proper small group of individuals as seeds for promotion but also determine the pricing of the commodity. To tackle the revenue maximization problem, we first introduce a strategic searching algorithm, referred to as Algorithm PRUB, which is able to derive the optimal solutions. After that, we further modify PRUB to propose a heuristic, Algorithm PRUB+IF, for obtaining feasible solutions more effciently on larger instances. Experiments on real social networks with different valuation distributions demonstrate the effectiveness of PRUB and PRUB+IF. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.06286v1.pdf"}
{"id": "1505.06648", "abstract": "  We demonstrate observational evidence for the occurrence of convectively driven internal gravity waves (IGW) in young massive O-type stars observed with high-precision CoRoT space photometry. This evidence results from a comparison between velocity spectra based on 2D hydrodynamical simulations of IGW in a differentially-rotating massive star and the observed spectra.We also show that the velocity spectra caused by IGW may lead to detectable line-profile variability and explain the occurrence of macroturbulence in the observed line profiles of OB stars. Our findings provide predictions that can readily be tested by including a sample of bright slowly and rapidly rotating OB-type stars in the scientific programme of the K2 mission accompanied by high-precision spectroscopy and their confrontation with multi-dimensional hydrodynamic simulations of IGW for various masses and ages. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.06648v2.pdf"}
{"id": "1505.07095", "abstract": "  Based on the phenomenological Skyrme interaction various density-dependent nuclear matter quantities are calculated up to second order in many-body perturbation theory. The spin-orbit term as well as two tensor terms contribute at second order to the energy per particle. The simultaneous calculation of the isotropic Fermi-liquid parameters provides a rigorous check through the validity of the Landau relations. It is found that published results for these second order contributions are incorrect in most cases. In particular, interference terms between s-wave and p-wave components of the interaction can contribute only to (isospin or spin) asymmetry energies. Even with nine adjustable parameters, one does not obtain a good description of the empirical nuclear matter saturation curve in the low density region 0<ρ<2ρ_0. The reason for this feature is the too strong density-dependence ρ^8/3 of several second-order contributions. The inclusion of the density-dependent term 1 6t_3 ρ^1/6 is therefore indispensable for a realistic description of nuclear matter in the Skyrme framework. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.07095v1.pdf"}
{"id": "1505.07433", "abstract": "  We propose and investigate different kinetic models for opinion formation, when the opinion formation process depends on an additional independent variable, e.g. a leadership or a spatial variable. More specifically, we consider:(i) opinion dynamics under the effect of opinion leadership, where each individual is characterised not only by its opinion, but also by another independent variable which quantifies leadership qualities; (ii) opinion dynamics modelling political segregation in the `The Big Sort', a phenomenon that US citizens increasingly prefer to live in neighbourhoods with politically like-minded individuals. Based on microscopic opinion consensus dynamics such models lead to inhomogeneous Boltzmann-type equations for the opinion distribution. We derive macroscopic Fokker-Planck-type equations in a quasi-invariant opinion limit and present results of numerical experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.07433v1.pdf"}
{"id": "1506.00352", "abstract": "  The knee phenomenon of the cosmic ray spectrum, which plays an important role in studying the acceleration mechanism of cosmic rays, is still an unsolved mystery. We try to reconcile the knee spectra measured by ARGO-YBJ and Tibet-III. A simple broken power-law model fails to explain the experimental data. Therefore a modified broken power-law model with non-linear acceleration effects is adopted, which can describe the sharp knee structure. This model predicts that heavy elements dominate at the knee. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1506/1506.00352v2.pdf"}
{"id": "1506.01611", "abstract": "  The next generation of multi-object spectrographs (MOS) will deliver comprehensive surveys of the Galaxy, Magellanic Clouds and nearby dwarfs. These will provide us with the vast samples, spanning the full extent of the Hertzsprung-Russell diagram, that are needed to explore the chemistry, history and dynamics of their host systems. Further ahead, the Extremely Large Telescopes (ELTs) will have sufficient sensitivity and angular resolution to extend stellar spectroscopy well beyond the Local Group, opening-up studies of the chemical evolution of galaxies across a broad range of galaxy types and environments. In this contribution I briefly reflect on current and future studies of stellar populations, and introduce plans for the MOSAIC instrument for the European ELT. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1506/1506.01611v1.pdf"}
{"id": "1506.04539", "abstract": "  We study an extended Bose-Hubbard model with next-nearest-neighbor (NNN) hopping in a shaken optical lattice. We show how mean-field phase diagram evolves with the change of NNN hopping amplitude t_2, which can be easily tuned via shaking amplitude. As t_2 increases, a Z_2-symmetry-breaking superfluid (Z_2SF) phase emerges at the bottom of the Mott lobs. The tricritical points between normal superfluid, Z_2SF, and Mott insulator (MI) phases are identified. We further demonstrate the tricritical point can be tuned to the tip of the Mott lobe, in which case a new critical behavior has been predicted. Within random-phase approximation, excitation spectra in the three phases are obtained, which indicate how the phase transitions occur. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1506/1506.04539v3.pdf"}
{"id": "1506.04972", "abstract": "  In this paper, we propose a successive pseudo-convex approximation algorithm to efficiently compute stationary points for a large class of possibly nonconvex optimization problems. The stationary points are obtained by solving a sequence of successively refined approximate problems, each of which is much easier to solve than the original problem. To achieve convergence, the approximate problem only needs to exhibit a weak form of convexity, namely, pseudo-convexity. We show that the proposed framework not only includes as special cases a number of existing methods, for example, the gradient method and the Jacobi algorithm, but also leads to new algorithms which enjoy easier implementation and faster convergence speed. We also propose a novel line search method for nondifferentiable optimization problems, which is carried out over a properly constructed differentiable function with the benefit of a simplified implementation as compared to state-of-the-art line search techniques that directly operate on the original nondifferentiable objective function. The advantages of the proposed algorithm are shown, both theoretically and numerically, by several example applications, namely, MIMO broadcast channel capacity computation, energy efficiency maximization in massive MIMO systems and LASSO in sparse signal recovery. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1506/1506.04972v2.pdf"}
{"id": "1506.05874", "abstract": "  Line-tension-induced scenario of heterogeneous nucleation is studied for a lens-shaped nucleus with a finite contact angle nucleated on a spherical substrate and on the bottom of the wall of a spherical cavity. The effect of line tension on the free energy of a critical nucleus can be separated from the usual volume term. By comparing the free energy of a lens-shaped critical nucleus of a finite contact angle with that of a spherical nucleus, we find that a spherical nucleus may have a lower free energy than a lens-shaped nucleus when the line tension is positive and large, which is similar to the drying transition predicted by Widom [B. Widom, J. Phys. Chem. 99 2803 (1995)]. Then, the homogeneous nucleation rather than the heterogeneous nucleation will be favorable. Similarly, the free energy of a lens-shaped nucleus becomes negative when the line tension is negative and large. Then, the barrier-less nucleation with no thermal activation called athermal nucleation will be realized. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1506/1506.05874v1.pdf"}
{"id": "1506.06262", "abstract": "  The frequency noise power spectral density of a free-running quantum cascade laser frequency comb is investigated. A plateau is observed at high frequencies, attributed to the quantum noise limit set by the Schawlow-Townes formula for the total laser power on all comb lines. In our experiment, a linewidth of 292 Hz is measured for a total power of 25 mW. This result proves that the four-wave mixing process, responsible for the comb operation, effectively correlates the quantum noise of the individual comb lines. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1506/1506.06262v1.pdf"}
{"id": "1507.00013", "abstract": "  A number of LHC resonance search channels display an excess in the invariant mass region of 1.8 - 2.0 TeV. Among them is a 3.4 σ excess in the fully hadronic decay of a pair of Standard Model electroweak gauge bosons, in addition to potential signals in the HW and dijet final states. We perform a model-independent cross-section fit to the results of all ATLAS and CMS searches sensitive to these final states. We then interpret these results in the context of the Left-Right Symmetric Model, based on the extended gauge group SU(2)_L× SU(2)_R× U(1)', and show that a heavy right-handed gauge boson W_R can naturally explain the current measurements with just a single coupling g_R ∼ 0.4. In addition, we discuss a possible connection to dark matter. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.00013v4.pdf"}
{"id": "1507.03655", "abstract": "  We develop a temperature measurement of an atomic cloud based on the temporal correlations of fluorescence photons evanescently coupled into an optical nanofiber. We measure the temporal width of the intensity-intensity correlation function due to atomic transit time and use it to determine the most probable atomic velocity, hence the temperature. This technique agrees well with standard time-of-flight temperature measurements. We confirm our results with trajectory simulations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.03655v1.pdf"}
{"id": "1507.03760", "abstract": "  A nonlinear kinetic theory, combining cosmic-ray (CR) acceleration in supernova remnants (SNRs) with their gas dynamics, is used to re-examine the nonthermal properties of the remnant of SN 1987A for an extended evolutionary period of 5-50 yr. This spherically symmetric model is approximately applied to the different features of the SNR which consist of (i) a blue supergiant wind and bubble, and (ii) of the swept-up red supergiant (RSG) wind structures in the form of an H II region, an equatorial ring (ER), and an hourglass region. The RSG wind involves a mass loss rate that decreases significantly with elevation above and below the equatorial plane. The model adapts recent three-dimensional hydrodynamical simulations by Potter et al. in 2014 that use a significantly smaller ionized mass of the ER than assumed in the earlier studies by the present authors. The SNR shock recently swept up the ER, which is the densest region in the immediate circumstellar environment. Therefore, the expected gamma-ray energy flux density at TeV energies in the current epoch has already reached its maximal value of ∼ 10^-13 erg cm^-2 s^-1. This flux should decrease by a factor of about two over the next 10 years. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.03760v4.pdf"}
{"id": "1507.04727", "abstract": "  We consider the problem of estimating the sparse time-varying parameter vectors of a point process model in an online fashion, where the observations and inputs respectively consist of binary and continuous time series. We construct a novel objective function by incorporating a forgetting factor mechanism into the point process log-likelihood to enforce adaptivity and employ ℓ_1-regularization to capture the sparsity. We provide a rigorous analysis of the maximizers of the objective function, which extends the guarantees of compressed sensing to our setting. We construct two recursive filters for online estimation of the parameter vectors based on proximal optimization techniques, as well as a novel filter for recursive computation of statistical confidence regions. Simulation studies reveal that our algorithms outperform several existing point process filters in terms of trackability, goodness-of-fit and mean square error. We finally apply our filtering algorithms to experimentally recorded spiking data from the ferret primary auditory cortex during attentive behavior in a click rate discrimination task. Our analysis provides new insights into the time-course of the spectrotemporal receptive field plasticity of the auditory neurons. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.04727v1.pdf"}
{"id": "1507.05822", "abstract": "  Inefficient screening of electric fields in nanoconductors makes electric manipulation of electronic transport in nanodevices possible. Accordingly, electrostatic (charge) gating is routinely used to affect and control the Coulomb electrostatics and quantum interference in modern nanodevices. Besides their charge, another (quantum mechanical) property of electrons - their spin - is at the heart of modern spintronics, a term implying that a number of magnetic and electrical properties of small systems are simultaneously harvested for device applications. In this review the possibility to achieve \"spin gating\" of mesoscopic devices, i.e. the possibility of an external spin control of the electronic properties of nanodevices is discussed. Rather than the Coulomb interaction, which is responsible for electric-charge gating, we consider two other mechanisms for spin gating. These are on the one hand the magnetic exchange interaction in magnetic devices and on the other hand the spin-orbit coupling (\"Rashba effect\"), which is prominent in low dimensional conductors. A number of different phenomena demonstrating the spin gating phenomenon will be discussed, including the spintro-mechanics of magnetic shuttling, Rashba spin splitting, and spin-gated weak superconductivity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.05822v1.pdf"}
{"id": "1507.06517", "abstract": "  Ensemble model output statistics (EMOS) is a statistical tool for post-processing forecast ensembles of weather variables obtained from multiple runs of numerical weather prediction models in order to produce calibrated predictive probability density functions (PDFs). The EMOS predictive PDF is given by a parametric distribution with parameters depending on the ensemble forecasts. We propose an EMOS model for calibrating wind speed forecasts based on weighted mixtures of truncated normal (TN) and log-normal (LN) distributions where model parameters and component weights are estimated by optimizing the values of proper scoring rules over a rolling training period. The new model is tested on wind speed forecasts of the 50 member European Centre for Medium-Range Weather Forecasts ensemble, the 11 member Aire Limitée Adaptation dynamique Développement International-Hungary Ensemble Prediction System ensemble of the Hungarian Meteorological Service and the eight-member University of Washington mesoscale ensemble, and its predictive performance is compared to that of various benchmark EMOS models based on single parametric families and combinations thereof. The results indicate improved calibration of probabilistic and accuracy of point forecasts in comparison with the raw ensemble and climatological forecasts. The mixture EMOS model significantly outperforms the TN and LN EMOS methods, moreover, it provides better calibrated forecasts than the TN-LN combination model and offers an increased flexibility while avoiding covariate selection problems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.06517v3.pdf"}
{"id": "1507.06924", "abstract": "  We work out the phenomenology of a model of supersymmetry breaking in the presence of a tiny (tunable) positive cosmological constant, proposed by the authors in arXiv:1403.1534. It utilises a single chiral multiplet with a gauged shift symmetry, that can be identified with the string dilaton (or an appropriate compactification modulus). The model is coupled to the MSSM, leading to calculable soft supersymmetry breaking masses and a distinct low energy phenomenology that allows to differentiate it from other models of supersymmetry breaking and mediation mechanisms. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.06924v1.pdf"}
{"id": "1507.07404", "abstract": "  In this letter, we present a detailed, all optical study of the influence of different excitation schemes on the indistinguishability of single photons from a single InAs quantum dot. For this study, we measure the Hong-Ou-Mandel interference of consecutive photons from the spontaneous emission of an InAs quantum dot state under various excitation schemes and different excitation conditions and give a comparison. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.07404v3.pdf"}
{"id": "1508.03488", "abstract": "  The selection of an equilibrium state by maximising the entropy of a system, subject to certain constraints, is often powerfully motivated as an exercise in logical inference, a procedure where conclusions are reached on the basis of incomplete information. But such a framework can be more compelling if it is underpinned by dynamical arguments, and we show how this can be provided by stochastic thermodynamics, where an explicit link is made between the production of entropy and the stochastic dynamics of a system coupled to an environment. The separation of entropy production into three components allows us to select a stationary state by maximising the change, averaged over all realisations of the motion, in the principal relaxational or nonadiabatic component, equivalent to requiring that this contribution to the entropy production should become time independent for all realisations. We show that this recovers the usual equilibrium probability density function (pdf) for a conservative system in an isothermal environment, as well as the stationary nonequilibrium pdf for a particle confined to a potential under nonisothermal conditions, and a particle subject to a constant nonconservative force under isothermal conditions. The two remaining components of entropy production account for a recently discussed thermodynamic anomaly between over- and underdamped treatments of the dynamics in the nonisothermal stationary state. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.03488v2.pdf"}
{"id": "1508.04534", "abstract": "  A system of equations for anisotropic hydrodynamics is derived that describes a mixture of anisotropic quark and gluon fluids. The consistent treatment of the zeroth, first and second moments of the kinetic equations allows us to construct a new framework with more general forms of the anisotropic phase-space distribution functions than those used before. In this way, the main difficiencies of the previous formulations of anisotropic hydrodynamics for mixtures have been overcome and the good agreement with the exact kinetic-theory results is obtained. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.04534v1.pdf"}
{"id": "1508.04622", "abstract": "  We present a method to accelerate the dynamical evolution of multiqubit open system by employing dynamical decoupling pulses (DDPs) when the qubits are initially in W-type states. It is found that this speed-up evolution can be achieved in both of the weak-coupling regime and the strong-coupling regime. The physical mechanism behind the acceleration evolution is explained as the result of the joint action of the non-Markovianity of reservoirs and the excited-state population of qubits. It is shown that both of the non-Markovianity and the excited-state population can be controlled by DDPs to realize the quantum speed-up. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.04622v1.pdf"}
{"id": "1508.06670", "abstract": "  We define a family of virtual knots generalizing the classical twist knots. We develop a recursive formula for the Alexander polynomial Δ_0 (as defined by Silver and Williams) of these virtual twist knots. These results are applied to provide evidence for a conjecture that the odd writhe of a virtual knot can be obtained from Δ_0. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.06670v1.pdf"}
{"id": "1508.06957", "abstract": "  We report the discovery of a large timescale candidate microlensing event of a bulge stellar source based on near-infrared observations with the VISTA Variables in the Via Lactea Survey (VVV). The new microlensing event is projected only 3.5 arcmin away from the center of the globular cluster NGC 6553. The source appears to be a bulge giant star with magnitude Ks = 13.52, based on the position in the color-magnitude diagram. The foreground lens may be located in the globular cluster, which has well-known parameters such as distance and proper motions. If the lens is a cluster member, we can directly estimate its mass simply following Paczynski et al. (1996) which is a modified version of the more general case due to Refsdal. In that case, the lens would be a massive stellar remnant, with M = 1.5-3.5 Msun. If the blending fraction of the microlensing event appears to be small, and this lens would represent a good isolated black hole (BH) candidate, that would be the oldest BH known. Alternative explanations (with a larger blending fraction) also point to a massive stellar remnant if the lens is located in the Galactic disk and does not belong to the globular cluster. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.06957v1.pdf"}
{"id": "1508.07727", "abstract": "  In this paper, we address the problem of optimal power allocation at the relay in two-hop secure communications under practical conditions. To guarantee secure communication during the long-distance transmission, the massive MIMO (M-MIMO) relaying techniques are explored to significantly enhance wireless security. The focus of this paper is on the analysis and design of optimal power assignment for a decode-and-forward (DF) M-MIMO relay, so as to maximize the secrecy outage capacity and minimize the interception probability, respectively. Our study reveals the condition for a nonnegative the secrecy outage capacity, obtains closed-form expressions for optimal power, and presents the asymptotic characteristics of secrecy performance. Finally, simulation results validate the effectiveness of the proposed schemes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.07727v1.pdf"}
{"id": "1508.07815", "abstract": "  The Energetic Neutral Atom (ENA) full-sky maps obtained with the Interstellar Boundary Explorer (IBEX) show an unexpected bright narrow band of increased intensity. This so-called ENA ribbon results from charge exchange of interstellar neutral atoms with protons in the outer heliosphere or beyond. Amongst other hypotheses it has been argued that this ribbon may be related to a neutral density enhancement, or H-wave, in the local interstellar medium. Here we quantitatively demonstrate, on the basis of an analytical model of the principal large-scale heliospheric structure, that this scenario for the ribbon formation leads to results that are fully consistent with the observed location of the ribbon in the full-sky maps at all energies detected with high-energy sensor IBEX-Hi. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.07815v1.pdf"}
{"id": "1509.00407", "abstract": "  Long gamma-ray bursts (GRBs) associated with supernovae and short GRBs with Extended Emission (SGRBEE) from mergers are probably powered by black holes as a common inner engine, as their prompt GRB emission satisfies the same Amati correlation in the E_p,i-E_iso plane. We introduce modified Bardeen equations to identify hyper-accretion driving newly formed black holes in core-collapse supernovae to near-extremal spin as a precursor to prompt GRB emission. Subsequent spin-down is observed in the BATSE catalog of long GRBs. Spin-down provides a natural unification of long durations associated with the lifetime of black hole spin for normal long GRBs and SGRBEEs, given the absence of major fallback matter in mergers. The results point to major emissions unseen in high frequency gravitational waves. A novel matched filtering method is described for LIGO-Virgo and KAGRA broadband probes of nearby core-collapse supernovae at essentially maximal sensitivity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.00407v1.pdf"}
{"id": "1509.01119", "abstract": "  Superconducting enclosures will be key components of scalable quantum computing devices based on circuit quantum electrodynamics (cQED). Within a densely integrated device, they can protect qubits from noise and serve as quantum memory units. Whether constructed by machining bulk pieces of metal or microfabricating wafers, 3D enclosures are typically assembled from two or more parts. The resulting seams potentially dissipate crossing currents and limit performance. In this Letter, we present measured quality factors of superconducting cavity resonators of several materials, dimensions and seam locations. We observe that superconducting indium can be a low-loss RF conductor and form low-loss seams. Leveraging this, we create a superconducting micromachined resonator with indium that has a quality factor of two million despite a greatly reduced mode volume. Inter-layer coupling to this type of resonator is achieved by an aperture located under a planar transmission line. The described techniques demonstrate a proof-of-principle for multilayer microwave integrated quantum circuits for scalable quantum computing. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.01119v2.pdf"}
{"id": "1509.02428", "abstract": "  We investigate how the Milky Way tidal field can affect the spatial mixing of multiple stellar populations in the globular cluster NGC 6362. We use N-body simulations of multiple population clusters on the orbit of this cluster around the Milky Way. Models of the formation of multiple populations in globular clusters predict that the second population should initially be more centrally concentrated than the first. However, NGC 6362 is comprised of two chemically distinct stellar populations having the same radial distribution. We show that the high mass loss rate experienced on this cluster's orbit significantly accelerates the spatial mixing of the two populations expected from two body relaxation. We also find that for a range of initial second population concentrations, cluster masses, tidal filling factors and fraction of first population stars, a cluster with two populations should be mixed when it has lost 70-80 per cent of its initial mass. These results fully account for the complete spatial mixing of NGC 6362, since, based on its shallow present day mass function, independent studies estimate that the cluster has lost 85 per cent of its initial mass. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.02428v2.pdf"}
{"id": "1509.03112", "abstract": "  QCD is well understood at short distances where perturbative calculations are feasible. Establishing an explicit analytic connection between the short-distance regime and the large-distance physics of quark confinement has been a long-sought goal. A major challenge is to relate the scale Λ_s underlying the evolution of the QCD coupling in the perturbative regime to the masses of hadrons. We show here how new theoretical insights into the behavior of QCD at large distances leads to such a relation. The resulting prediction for Λ_s in the MS scheme agrees well with experimental measurements. Conversely, the relation can be used to predict the masses of hadrons composed of light quarks with the measured value of Λ_s as the sole parameter. We also use \"light-front holography\" to determine the analytic form of α_s(Q^2) at small Q^2. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.03112v1.pdf"}
{"id": "1509.03578", "abstract": "  In this paper, we theoretically show that a broadband resonant enhancement of emission may occur for infrared sources located in a polaritonic wire medium. The reason of this enhancement is overlapping of two topological transitions of the wave dispersion in the medium. The first topological transition has been recently revealed as an effect inherent to polaritonic wire media. The second one was theoretically uncovered in another material. In this work we reveal it for wire media and prove the possibility to combine both these transitions with the purpose to obtain the broadband resonant Purcell factor. We compare the results obtained for two orientations of a subwavelength electric dipole embedded into wire medium – that along the optical axis and that perpendicular to it – and report on the resonant isotropic radiation enhancement. Also, we reveal the enhancement of radiation to free space from a finite sample of the wire medium. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.03578v1.pdf"}
{"id": "1509.04369", "abstract": "  In this study, we investigate the dispersive properties of smoothed particle magnetohydrodynamics (SPM) in a strongly magnetized medium by using linear analysis. In modern SPM, a correction term proportional to the divergence of the magnetic fields is subtracted from the equation of motion to avoid a numerical instability arising in a strongly magnetized medium. From the linear analysis, it is found that SPM with the correction term suffer from significant dispersive errors, especially for slow waves propagating along magnetic fields. The phase velocity for all wave numbers is significantly larger than the exact solution and has a peak at a finite wavenumber. These excessively large dispersive errors occur because magnetic fields contribute an unphysical repulsive force along magnetic fields. The dispersive errors cannot be reduced, even with a larger smoothing length and smoother kernel functions such as the Gaussian or quintic spline kernels. We perform the linear analysis for this problem and find that the dispersive errors can be removed completely while keeping SPM stable if the correction term is reduced by half. These findings are confirmed by several simple numerical experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.04369v1.pdf"}
{"id": "1509.06052", "abstract": "  This paper is a contribution to the memorial session for Michel Borghini at the Spin 2014 conference in Bejing, honoring his pivotal role for the development of polarized targets in high energy physics. Borghini proposed for the first time the correct mechanism for dynamic polarization in polarized targets using organic materials doped with free radicals. In these amorphous materials the spin levels are broadened by spin-spin interactions and g-factor anisotropy, which allows a high dynamic polarization of nuclei by cooling of the spin-spin interaction reservoir. In this contribution I summarize the experimental evidence for this mechanism. These pertinent experiments were done at CERN in the years 1971 - 1974, when I was a graduate student under the guidance of Michel Borghini. I finish by shortly describing how Borghini's spin temperature theory is now applied in cancer therapy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.06052v1.pdf"}
{"id": "1509.06291", "abstract": "  A fluid between two spheres, concentric or not, at different temperatures will flow in the presence of a constant gravitational force. Although there is no possible hydrostatic state, energy transport is dominated by diffusion if temperature difference between the spheres is small enough. In this conductive regime the average Nusselt number remains approximately constant for all Rayleigh numbers below some critical value. Above the critical Rayleigh number, plumes appear and thermal convection takes place. We study this phenomenon, in particular the case where the inner sphere is displaced from the centre, using a two-component thermal lattice Boltzmann method to characterize the convective instability, the evolution of the flow patterns and the dependence of the Nusselt number on the Rayleigh number beyond the transition. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.06291v1.pdf"}
{"id": "1509.07614", "abstract": "  Measuring incomplete sets of mutually unbiased bases constitutes a sensible approach to the tomography of high-dimensional quantum systems. The unbiased nature of these bases optimizes the uncertainty hypervolume. However, imposing unbiasedness on the probabilities for the unmeasured bases does not generally yield the estimator with the largest von Neumann entropy, a popular figure of merit in this context. Furthermore, this imposition typically leads to mock density matrices that are not even positive definite. This provides a strong argument against perfunctory applications of linear estimation strategies. We propose to use instead the physical state estimators that maximize the Shannon entropy of the unmeasured outcomes, which quantifies our lack of knowledge fittingly and gives physically meaningful statistical predictions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.07614v1.pdf"}
{"id": "1510.00034", "abstract": "  We explore the collective phase dynamics of Wien-bridge oscillators coupled resistively. We carefully analyze the behavior of two coupled oscillators, obtaining a transformation from voltage to effective phase. From the phase dynamics we show that the coupling can be quantitatively described by Sakaguchi's modification to the Kuramoto model. We also examine an ensemble of oscillators whose frequencies are taken from a flat distribution within a fixed frequency interval. We characterize in detail the synchronized cluster, its initial formation, as well as its effect on unsynchronized oscillators, all as a function of a global coupling strength. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.00034v2.pdf"}
{"id": "1510.00116", "abstract": "  In this paper, we describe a novel algorithm to create a con- current wait-free stack. To the best of our knowledge, this is the first wait-free algorithm for a general purpose stack. In the past, researchers have proposed restricted wait-free implementations of stacks, lock-free implementations, and efficient universal constructions that can support wait-free stacks. The crux of our wait-free implementation is a fast pop operation that does not modify the stack top; instead, it walks down the stack till it finds a node that is unmarked. It marks it but does not delete it. Subsequently, it is lazily deleted by a cleanup operation. This operation keeps the size of the stack in check by not allowing the size of the stack to increase beyond a factor of W as compared to the actual size. All our operations are wait-free and linearizable. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.00116v1.pdf"}
{"id": "1510.01848", "abstract": "  We consider the Black–Scholes model of financial market modified to capture the stochastic nature of volatility observed at real financial markets. For volatility driven by the Ornstein–Uhlenbeck process, we establish the existence of equivalent martingale measure in the market model. The option is priced with respect to the minimal martingale measure for the case of uncorrelated processes of volatility and asset price, and an analytic expression for the price of European call option is derived. We use the inverse Fourier transform of a characteristic function and the Gaussian property of the Ornstein–Uhlenbeck process. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.01848v1.pdf"}
{"id": "1510.03680", "abstract": "  We introduce a new Monte Carlo model based on a semi-empirical sputter yield parameter in ion-solid energetic collisions. This model circumvents the complexity of the existing statistical, classical and continuum models, most of which are difficult to relate to real experimental parameters, by its semi-empirical nature of direct reliance on the experimental values of the sputter yield. Constrained by this crucial experimental factor, the model then addresses the multidimensional nature of other accompanying physical processes stochastically; thus reducing the complexity of their computation. This model exhibits the experimentally observed features of solid surfaces that evolve under continuous particle irradiation and allows for a way to study the effect of the different mechanisms of the surface morphology and the nature of their interplay in the dynamics of the surface evolution. Our study of the average surface height reveals that it is constant when eroded particles are redeposited but varies linearly with simulation time, when eroded particles are not redeposited. Our studies also show that the roughening process is not significantly affected by re-deposition of eroded material. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.03680v1.pdf"}
{"id": "1510.03746", "abstract": "  Liquid water is not only of obvious importance but also extremely intriguing, displaying many anomalies that still challenge our understanding of such an a priori simple system. The same is true when looking at nanoconfined water: The liquid between constituents in a cell is confined to such dimensions, and there is already evidence that such water can behave very differently from its bulk counterpart. A striking finding has been reported from computer simulations for two-dimensionally confined water: The liquid displays continuous or discontinuous melting depending on its density. In order to understand this behavior, we have analyzed the melting exhibited by a bilayer of nanoconfined water by means of molecular dynamics simulations. At high density we observe the continuous melting to be related to the phase change of the oxygens only, with the hydrogens remaining liquid-like throughout. Moreover, we find an intermediate hexatic phase for the oxygens between the liquid and a triangular solid ice phase, following the Kosterlitz-Thouless-Halperin-Nelson-Young theory for two-dimensional melting. The liquid itself tends to maintain the local structure of the triangular ice, with its two layers being strongly correlated, yet with very slow exchange of matter. The decoupling in the behavior of the oxygens and hydrogens gives rise to a regime in which the complexity of water seems to disappear, resulting in what resembles a simple monoatomic liquid. This intrinsic tendency of our simulated water may be useful for understanding novel behaviors in other confined and interfacial water systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.03746v3.pdf"}
{"id": "1510.04770", "abstract": "  The integrated Sachs-Wolfe (ISW) effect and its non-linear extension Rees-Sciama (RS) effect provide us the information of the time evolution of gravitational potential. The cross-correlation between the cosmic microwave background (CMB) and the large scale structure (LSS) is known as a promising way to extract the ISW (RS) effect. It is known that the RS effect shows the unique behavior by changing the anti-correlated cross correlation between the CMB and the mass tracer into the positively correlated cross correlation compared to the linear ISW effect. We show that the dependence of this flipping scale of the cross-correlation between RS and weak lensing on dark energy models. However, there exists the degeneracy between DE and Ω_m0 which might be broken by redshift dependent observables. The cross-correlation between the momentum field and the density field might be served as the better observable to be used for this purpose. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.04770v1.pdf"}
{"id": "1510.04895", "abstract": "  We study Chebyshev filter diagonalization as a tool for the computation of many interior eigenvalues of very large sparse symmetric matrices. In this technique the subspace projection onto the target space of wanted eigenvectors is approximated with filter polynomials obtained from Chebyshev expansions of window functions. After the discussion of the conceptual foundations of Chebyshev filter diagonalization we analyze the impact of the choice of the damping kernel, search space size, and filter polynomial degree on the computational accuracy and effort, before we describe the necessary steps towards a parallel high-performance implementation. Because Chebyshev filter diagonalization avoids the need for matrix inversion it can deal with matrices and problem sizes that are presently not accessible with rational function methods based on direct or iterative linear solvers. To demonstrate the potential of Chebyshev filter diagonalization for large-scale problems of this kind we include as an example the computation of the 10^2 innermost eigenpairs of a topological insulator matrix with dimension 10^9 derived from quantum physics applications. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.04895v2.pdf"}
{"id": "1510.04940", "abstract": "  The future wireless network, such as Centralized Radio Access Network (C-RAN), will need to deliver data rate about 100 to 1000 times the current 4G technology. For C-RAN based network architecture, there is a pressing need for tremendous enhancement of the effective data rate of the Common Public Radio Interface (CPRI). Compression of CPRI data is one of the potential enhancements. In this paper, we introduce a vector quantization based compression algorithm for CPRI links, utilizing Lloyd algorithm. Methods to vectorize the I/Q samples and enhanced initialization of Lloyd algorithm for codebook training are investigated for improved performance. Multi-stage vector quantization and unequally protected multi-group quantization are considered to reduce codebook search complexity and codebook size. Simulation results show that our solution can achieve compression of 4 times for uplink and 4.5 times for downlink, within 2", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.04940v1.pdf"}
{"id": "1510.05582", "abstract": "  We have used a plane-wave expansion method to theoretically study the far-field head-media optical interaction in HAMR. For the ASTC media stack specifically, we notice the outstanding sensitivity related to interlayer's optical thickness for media reflection and magnetic layer's light absorption. With 10-nm interlayer thickness change, the recording layer absorption can be changed by more than 25", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.05582v2.pdf"}
{"id": "1510.07149", "abstract": "  The so-called Lindley paradox is a counterintuitive statistical effect where the Bayesian and frequentist approaches to hypothesis testing give radically different answers, depending on the choice of the prior distribution. In this paper we address the occurrence of the Lindley paradox in optical interferometry and discuss its implications for high-precision measurements. In particular, we focus on phase estimation by Mach-Zehnder interferometers and show how to mitigate the conflict between the two approaches by using suitable priors. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.07149v1.pdf"}
{"id": "1510.08032", "abstract": "  We present a combined experimental and theoretical study of the effects of Rydberg interactions on Autler-Townes spectra of ultracold gases of atomic strontium. Realizing two-photon Rydberg excitation via a long-lived triplet state allows us to probe the thus far unexplored regime where Rydberg state decay presents the dominant decoherence mechanism. The effects of Rydberg interactions are observed in shifts, asymmetries, and broadening of the measured atom-loss spectra. The experiment is analyzed within a one-body density matrix approach, accounting for interaction-induced level shifts and dephasing through nonlinear terms that approximately incorporate correlations due to the Rydberg blockade. This description yields good agreement with our experimental observations for short excitation times. For longer excitation times, the loss spectrum is altered qualitatively, suggesting additional dephasing mechanisms beyond the standard blockade mechanism based on pure van der Waals interactions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.08032v1.pdf"}
{"id": "1510.08066", "abstract": "  A tidal disruption event, which occurs when a star is destroyed by the gravitational field of a supermassive black hole, produces a stream of debris, the evolution of which ultimately determines the observational properties of the event. Here we show that a post-periapsis caustic – a location where the locus of gas parcels comprising the stream would collapse into a two-dimensional surface if they evolved solely in the gravitational field of the hole – occurs when the pericenter distance of the star is on the order of the tidal radius of the hole. It is demonstrated that this \"pancake\" induces significant density perturbations in the debris stream, and, for stiffer equations of state (adiabatic index γ≳ 5/3), these fluctuations are sufficient to gravitationally destabilize the stream, resulting in its fragmentation into bound clumps. The results of our findings are discussed in the context of the observational properties of tidal disruption events. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.08066v1.pdf"}
{"id": "1510.08428", "abstract": "  Microwave photons inside lattices of coupled resonators and superconducting qubits can exhibit surprising matter-like behavior. Realizing such open-system quantum simulators presents an experimental challenge and requires new tools and measurement techniques. Here, we introduce Scanning Defect Microscopy as one such tool and illustrate its use in mapping the normal-mode structure of microwave photons inside a 49-site Kagome lattice of coplanar waveguide resonators. Scanning is accomplished by moving a probe equipped with a sapphire tip across the lattice. This locally perturbs resonator frequencies and induces shifts of the lattice resonance frequencies which we determine by measuring the transmission spectrum. From the magnitude of mode shifts we can reconstruct photon field amplitudes at each lattice site and thus create spatial images of the photon-lattice normal modes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.08428v1.pdf"}
{"id": "1511.01027", "abstract": "  Recently an alternative way to quantify Bell nonlocality has been proposed [Phys. Rev. A 92, 030101(R) (2015)]. In this work we further develop this concept, the volume of violation, and analytically calculate its value for the spin-singlet state with respect to the settings of the first Bell's inequality. These settings correspond to three directions in space, or three arbitrary points on the unit sphere. It is shown that the triples of directions that lead to violations in local causality correspond to 1/3 of all possible configurations. From the perspective of quantum communications, this means that two distant parties that were capable of align their measurements in one direction only (the remaining direction in each site being random), have a probability of about 33.3% to be able to certify their entanglement. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.01027v2.pdf"}
{"id": "1511.02735", "abstract": "  We have measured the linear polarisation of hard X-ray emission from the Crab in a previously unexplored energy interval, 20-120 keV. The introduction of two new observational parameters, the polarisation fraction and angle stands to disentangle geometrical and physical effects, thereby providing information on the pulsar wind geometry and magnetic field environment. Measurements are conducted using the PoGOLite Pathfinder - a balloon-borne polarimeter. Polarisation is determined by measuring the azimuthal Compton scattering angle of incident X-rays in an array of plastic scintillators housed in an anticoincidence well. The polarimetric response has been characterised prior to flight using both polarised and unpolarised calibration sources. We address possible systematic effects through observations of a background field. The measured polarisation fraction for the integrated Crab light-curve is (18.4^+9.8_-10.6)", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.02735v2.pdf"}
{"id": "1511.03569", "abstract": "  We report on the state of the art of quantum walk experiments with neutral atoms in state-dependent optical lattices. We demonstrate a novel state-dependent transport technique enabling the control of two spin-selective sublattices in a fully independent fashion. This transport technique allowed us to carry out a test of single-particle quantum interference based on the violation of the Leggett-Garg inequality and, more recently, to probe two-particle quantum interference effects with neutral atoms cooled into the motional ground state. These experiments lay the groundwork for the study of discrete-time quantum walks of strongly interacting, indistinguishable particles to demonstrate quantum cellular automata of neutral atoms. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.03569v1.pdf"}
{"id": "1511.07258", "abstract": "  Analysis of a large set of phase-resolved K-band spectra of the cataclysmic variable WZ Sge shows that the secondary star of this system appears to be an L-dwarf. Previous K-band spectra of WZ Sge found that the CO overtone bandheads were in emission. We show that absorption from the ^ 12CO_ (2,0) bandhead of the donor star creates a dip in the ^ 12CO_ (2,0) emission feature. Measuring the motion of this feature over the orbital period, we construct a radial velocity curve that gives a velocity amplitude of K_ abs = 520 ± 35 km s^ -1, consistent with the previously published values for this parameter. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.07258v1.pdf"}
{"id": "1511.08977", "abstract": "  In this paper, we endeavour to seek a fundamental understanding of the potentials and limitations of training-based multiuser multiple-input multiple-output (MIMO) systems. In a multiuser MIMO system, users are geographically separated. So, the near-far effect plays an indispensable role in channel fading. The existing optimal training design for conventional MIMO does not take the near-far effect into account, and thus is not applicable to a multiuser MIMO system. In this work, we use the majorization theory as a basic tool to study the tradeoff between the channel estimation quality and the information throughput. We establish tight upper and lower bounds of the throughput, and prove that the derived lower bound is asymptotically optimal for throughput maximization at high signal-to-noise ratio. Our analysis shows that the optimal training sequences for throughput maximization in a multiuser MIMO system are in general not orthogonal to each other. Furthermore, due to the near-far effect, the optimal training design for throughput maximization is to deactivate a portion of users with the weakest channels in transmission. These observations shed light on the practical design of training-based multiuser MIMO systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.08977v2.pdf"}
{"id": "1512.00659", "abstract": "  Support Vector Machines (SVMs) were primarily designed for 2-class classification. But they have been extended for N-class classification also based on the requirement of multiclasses in the practical applications. Although N-class classification using SVM has considerable research attention, getting minimum number of classifiers at the time of training and testing is still a continuing research. We propose a new algorithm CBTS-SVM (Centroid based Binary Tree Structured SVM) which addresses this issue. In this we build a binary tree of SVM models based on the similarity of the class labels by finding their distance from the corresponding centroids at the root level. The experimental results demonstrates the comparable accuracy for CBTS with OVO with reasonable gamma and cost values. On the other hand when CBTS is compared with OVA, it gives the better accuracy with reduced training time and testing time. Furthermore CBTS is also scalable as it is able to handle the large data sets. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.00659v1.pdf"}
{"id": "1512.01141", "abstract": "  We studied the quantum correlations between the nodes in a quantum neural network built of an array of quantum dots with dipole-dipole interaction. By means of the quasiadiabatic path integral simulation of the density matrix evolution in a presence of the common phonon bath we have shown the coherence in such system can survive up to the liquid nitrogen temperature of 77K and above. The quantum correlations between quantum dots are studied by means of calculation of the entanglement of formation in a pair of quantum dots with the typical dot size of a few nanometers and the interdot distance of the same order. We have shown that the proposed quantum neural network can keep the mixture of entangled states of QD pairs up to the above mentioned high temperatures. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.01141v2.pdf"}
{"id": "1512.01886", "abstract": "  Temporal contact networks are studied to understand dynamic spreading phenomena such as communicable diseases or information dissemination. To establish how spatiotemporal dynamics of nodes impact spreading potential in colocation contact networks, we propose \"inducement-shuffling\" null models which break one or more correlations between times, locations and nodes. By reconfiguring the time and/or location of each node's presence in the network, these models induce alternative sets of colocation events giving rise to contact networks with varying spreading potential. This enables second-order causal reasoning about how correlations in nodes' spatiotemporal preferences not only lead to a given contact network but ultimately influence the network's spreading potential. We find the correlation between nodes and times to be the greatest impediment to spreading, while the correlation between times and locations slightly catalyzes spreading. Under each of the presented null models we measure both the number of contacts and infection prevalence as a function of time, with the surprising finding that the two have no direct causality. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.01886v2.pdf"}
{"id": "1512.03118", "abstract": "  In this paper we analyze some properties of a scalar field configuration, where it is considered as a trapped Bose-Einstein condensate in a Schwarzschild-de Sitter background spacetime. In a natural way, the geometry of the curved spacetime provides an effective trapping potential for the scalar field configuration. This allows us to explore some thermodynamical properties of the system. Additionally, the curved geometry of the spacetime also induces a position dependent self-interaction parameter, which can be interpreted as a kind of gravitational Feshbach resonance, that could affect the stability of the cloud and could be used to obtain information about the interactions among the components of the system.. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.03118v2.pdf"}
{"id": "1512.03320", "abstract": "  We investigate a method of selectively targeting cancer cells by means of ultrasound harmonic excitation at their resonance frequency, which we refer to as oncotripsy. The geometric model of the cells takes into account the cytoplasm, nucleus and nucleolus, as well as the plasma membrane and nuclear envelope. Material properties are varied within a pathophysiologically-relevant range. A first modal analysis reveals the existence of a spectral gap between the natural frequencies and, most importantly, resonant growth rates of healthy and cancerous cells. The results of the modal analysis are verified by simulating the fully-nonlinear transient response of healthy and cancerous cells at resonance. The fully nonlinear analysis confirms that cancerous cells can be selectively taken to lysis by the application of carefully tuned ultrasound harmonic excitation while simultaneously leaving healthy cells intact. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.03320v2.pdf"}
{"id": "1512.04196", "abstract": "  Motivated by the interest in non-relativistic quantum mechanics for determining exact solutions to the Schrodinger equation we give two potentials that are conditionally exactly solvable. The two potentials are partner potentials and we obtain that each linearly independent solution of the Schrodinger equation includes two hypergeometric functions. Furthermore we calculate their reflection and transmission amplitudes. Finally we discuss some additional properties of these potentials. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.04196v1.pdf"}
{"id": "1512.04348", "abstract": "  The first challenge in robustness analysis of large-scale interconnected uncertain systems is to provide a model of such systems in a standard-form that is required within different analysis frameworks. This becomes particularly important for large-scale systems, as analysis tools that can handle such systems heavily rely on the special structure within such model descriptions. We here propose an automated framework for providing such models of large-scale interconnected uncertain systems that are used in Integral Quadratic Constraint (IQC) analysis. Specifically, in this paper we put forth a methodological way to provide such models from a block-diagram and nested description of interconnected uncertain systems. We describe the details of this automated framework using an example. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.04348v1.pdf"}
{"id": "1601.00013", "abstract": "  The possibility of approximating a continuous function on a compact subset of the real line by a feedforward single hidden layer neural network with a sigmoidal activation function has been studied in many papers. Such networks can approximate an arbitrary continuous function provided that an unlimited number of neurons in a hidden layer is permitted. In this paper, we consider constructive approximation on any finite interval of ℝ by neural networks with only one neuron in the hidden layer. We construct algorithmically a smooth, sigmoidal, almost monotone activation function σ providing approximation to an arbitrary continuous function within any degree of accuracy. This algorithm is implemented in a computer program, which computes the value of σ at any reasonable point of the real axis. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.00013v2.pdf"}
{"id": "1601.00446", "abstract": "  We theoretically and numerically study spin-wave turbulence in spin-1 ferromagnetic spinor Bose-Einstein condensates, finding direct and inverse cascades with power-law behavior. To derive these power exponents analytically, the conventional weak wave turbulence theory is applied to the spin-1 spinor Gross-Pitaevskii equation. Thus, we obtain the -7/3 and -5/3 power laws in the transverse spin correlation function for the direct and inverse cascades, respectively. To confirm these power laws, numerical calculations are performed that obtain results consistent with these power laws. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.00446v2.pdf"}
{"id": "1601.01718", "abstract": "  We apply the concept of superradiance introduced by Dicke in 1954 to the OH molecule 1612 MHz spectral line often used for the detection of masers in circumstellar envelopes of evolved stars. As the detection of 1612 MHz OH masers in the outer shells of envelopes of these stars implies the existence of a population inversion and a high level of velocity coherence, and that these are two necessary requirements for superradiance, we investigate whether superradiance can also happen in these regions. Superradiance is characterized by high intensity, spatially compact, burst-like features taking place over time-scales on the order of seconds to years, depending on the size and physical conditions present in the regions harboring such sources of radiation. Our analysis suggests that superradiance provides a valid explanation for previous observations of intensity flares detected in that spectral line for the U Orionis Mira star and the IRAS18276-1431 pre-planetary nebula. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.01718v2.pdf"}
{"id": "1601.02518", "abstract": "  External passive femtosecond enhancement cavities (fsECs) are widely used to increase the efficiency of non-linear conversion processes like high harmonic generation (HHG) at high repetition rates. Their performance is often limited by beam ellipticity, caused by oblique incidence on spherical focusing mirrors. We introduce a novel three-dimensionally folded variant of the typical planar bow-tie resonator geometry that guarantees circular beam profiles, maintains linear polarization, and allows for a significantly tighter focus as well as a larger beam cross-section on the cavity mirrors. The scheme is applied to improve focusing in a Ti:Sapphire based VUV frequency comb system, targeting the 5th harmonic around 160 nm (7.8 eV) towards high-precision spectroscopy of the low-energy isomer state of Thorium-229. It will also be beneficial in fsEC-applications with even higher seeding and intracavity power where the damage threshold of the mirrors becomes a major concern. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.02518v1.pdf"}
{"id": "1601.02868", "abstract": "  The study of the adsorption phenomenon of helium began many decades ago with the discovery of graphite as a homogeneous substrate for investigation of physically adsorbed monolayer films. In particular, helium monoatomic layers on graphite were found to exhibit a very rich phase diagram.   In the present work we have investigated the adsorption phenomenon of helium atoms on graphene and silicene substrates by means of density functional theory with Born-Oppenheimer approximation. Helium-substrate and helium-helium interactions were considered from first principles. Vibrational properties of adsorbed monolayers have been used to explore the stability of the system. This approach reproduces results describing the stability of a helium monolayer on graphene calculated by quantum Monte Carlo (QMC) simulations for low and high coverage cases. However, for the moderate coverage value there is discrepancy with QMC results due to the lack of helium zero point motion. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.02868v1.pdf"}
{"id": "1601.06232", "abstract": "  In the simplest Higgs-portal scalar dark matter model, the dark matter mass has been restricted to be either near the resonant mass (m_h/2) or in a large-mass region by the direct detection at LHC Run 1 and LUX. While the large-mass region below roughly 3 TeV can be probed by the future Xenon1T experiment, most of the resonant mass region is beyond the scope of Xenon1T. In this paper, we study the direct detection of such scalar dark matter in the narrow resonant mass region at the 14 TeV LHC and the future 100 TeV hadron collider. We show the luminosities required for the 2σ exclusion and 5σ discovery. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.06232v2.pdf"}
{"id": "1601.07892", "abstract": "  We apply a generalized model for the determination and analysis of the dielectric function of optically anisotropic materials with colour dispersion to phonon modes and show that it can also be generalized to excitonic polarizabilities and electronic band-band transitions. We take into account that the tensor components of the dielectric function within the cartesian coordinate system are not independent from each other but are rather projections of the polarization of dipoles oscillating along directions defined by the, non-cartesian, crystal symmetry and polarizability. The dielectric function is then composed of a series of oscillators pointing in different directions. The application of this model is exemplarily demonstrated for monoclinic (β-phase) Ga_2O_3 bulk single crystals. Using this model, we are able to relate electronic transitions observed in the dielectric function to atomic bond directions and orbitals in the real space crystal structure. For thin films revealing rotational domains we show that the optical biaxiality is reduced to uniaxial optical response. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.07892v1.pdf"}
{"id": "1602.00256", "abstract": "  In the present paper, we discuss contra-arguments concerning the use of Pareto-Levý distributions for modeling in Finance. It appears that such probability laws do not provide sufficient number of outliers observed in real data. Connection with the classical limit theorem for heavy-tailed distributions with such type of models is also questionable. The idea of alternative modeling is given. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.00256v1.pdf"}
{"id": "1602.00822", "abstract": "  We study the generalization of the Kerr-Newmann black hole in 5D Einstein-Maxwell-Chern-Simons theory with free Chern-Simons coupling parameter. These black holes possess equal magnitude angular momenta and an event horizon of spherical topology. We focus on the extremal case with zero temperature. We find that, when the Chern-Simons coupling is greater than two times the supergravity case, new branches of black holes are found which violate uniqueness. In particular, a sequence of these black holes are non-static radially excited solutions with vanishing angular momentum. They approach the Reissner-Nordström solution as the excitation level increases. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.00822v1.pdf"}
{"id": "1602.02624", "abstract": "  We propose a method to generate a single peak at a distinct energy in the ion flux-energy distribution function (IDF) at the electrode surfaces in capacitively coupled plasmas. The technique is based on the tailoring of the driving voltage waveform, i.e. adjusting the phases and amplitudes of the applied harmonics, to optimize the accumulation of ions created by charge exchange collisions and their subsequent acceleration by the sheath electric field. The position of the peak (i.e. the ion energy) and the flux of the ions within the peak of the IDF can be controlled in a wide domain by tuning the parameters of the applied RF voltage waveform, allowing optimization of various applications where surface reactions are induced at particular ion energies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.02624v1.pdf"}
{"id": "1602.05004", "abstract": "  Inspired by the generalized uncertainty principle (GUP), which adds gravitational effects to the standard description of quantum uncertainty, we extend the exact uncertainty principle (EUP) approach by Hall and Reginatto [J. Phys. A: Math. Gen. (2002) 35 3289], and obtain a (quasi)nonlinear Schrödinger equation. This quantum evolution equation of unusual form, enjoys several desired properties like separation of non-interacting subsystems or planewave solutions for free particles. Starting with the harmonic oscillator example, we show that every solution of this equation respects the gravitationally-induced minimal position uncertainty proportional to the Planck length. Quite surprisingly, our result successfully merges the core of classical physics with non-relativistic quantum mechanics in its extremal form. We predict that the commonly accepted phenomenon, namely a modification of a free-particle dispersion relation due to quantum gravity might not occur in reality. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.05004v2.pdf"}
{"id": "1602.05140", "abstract": "  Short Gamma-Ray Bursts (GRBs) are explosions of cosmic origin believed to be associated with the merger of two compact objects, either two neutron stars, or a neutron star and a black hole. The presence of at least one neutron star has long been thought to be an essential element of the model: its tidal disruption provides the needed baryonic material whose rapid accretion onto the post-merger black hole powers the burst. The recent tentative detection by the Fermi satellite of a short GRB in association with the gravitational wave signal GW150914 produced by the merger of two black holes has challenged this standard paradigm. Here we show that the evolution of two high-mass, low-metallicity stars with main sequence rotational speeds a few tens of percent of the critical speed eventually undergoing a weak supernova explosion can produce a short gamma-ray burst. The outer layers of the envelope of the last exploding star remain bound and circularize at large radii. With time, the disk cools and becomes neutral, suppressing the magneto-rotational instability, and hence the viscosity. The disk remains 'long-lived dead' until tidal torques and shocks during the pre-merger phase heat it up and re-ignite accretion, rapidly consuming the disk and powering the short gamma-ray burst. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.05140v2.pdf"}
{"id": "1602.05497", "abstract": "  The method of simulated annealing is adapted to the temperature-emissivity separation (TES) problem. A patch of surface at the bottom of the atmosphere is assumed to be a greybody emitter with spectral emissivity ϵ(k) describable by a mixture of spectral endmembers. We prove that a simulated annealing search conducted according to a suitable schedule converges to a solution maximizing the A-Posteriori probability that spectral radiance detected at the top of the atmosphere originates from a patch with stipulated T and ϵ(k). Any such solution will be nonunique. The average of a large number of simulated annealing solutions, however, converges almost surely to a unique Maximum A-Posteriori solution for T and ϵ(k). The limitation to a stipulated set of endmember emissivities may be relaxed by allowing the number of endmembers to grow without bound, and to be generic continuous functions of wavenumber with bounded first derivatives with respect to wavenumber. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.05497v1.pdf"}
{"id": "1602.05519", "abstract": "  We explore the electronic structure and transport properties of a metal on top of a (weakly coupled) two-dimensional topological insulator. Unlike the widely studied junctions between topological non-trivial materials, the systems studied here allow for a unique bandstructure and transport steering. First, states on the topological insulator layer may coexist with the gapless bulk and, second, the edge states on one edge can be selectively switched-off, thereby leading to nearly perfect directional transport of charge and spin even in the zero bias limit. We illustrate these phenomena for Bernal stacked bilayer graphene with Haldane or intrinsic spin-orbit terms and a perpendicular bias voltage. This opens a path for realizing directed transport in materials such as van der Waals heterostructures, monolayer and ultrathin topological insulators. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.05519v1.pdf"}
{"id": "1602.05938", "abstract": "  Perfect single-crystal neutron interferometers are adversely sensitive to environmental disturbances, particularly mechanical vibrations. The sensitivity to vibrations results from the slow velocity of thermal neutrons and the long measurement time that are encountered in a typical experiment. Consequently, to achieve a good interference solutions for reducing vibration other than those normally used in optical experiments must be explored. Here we introduce a geometry for a neutron interferometer that is less sensitive to low-frequency vibrations. This design may be compared with both dynamical decoupling methods and decoherence-free subspaces that are described in quantum information processing. By removing the need for bulky vibration isolation setups, this design will make it easier to adopt neutron interferometry to a wide range of applications and increase its sensitivity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.05938v1.pdf"}
{"id": "1602.05997", "abstract": "  Horndeski gravity holds a special position as the most general extension of Einstein's theory of general relativity with a single scalar degree of freedom and second-order field equations. Because of these features, Horndeski gravity is an attractive phenomenological playground to investigate the consequences of modifications of general relativity in cosmology and astrophysics. We present a review of the progress made so far in the study of compact objects (black holes and neutron stars) within Horndeski gravity. In particular, we review our recent work on slowly rotating black holes and present some new results on slowly rotating neutron stars. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.05997v2.pdf"}
{"id": "1602.06125", "abstract": "  The low-frequency instability of a cylindrical poorly magnetized plasma with an inward-directed radial electric field is studied changing the gas pressure and the ion cyclotron frequency. The unstable frequency always decreases when the gas pressure is increased indicating collisional effects. At a fixed pressure, the unstable frequency increases with the magnetic field when the B-field is low and decreases at larger magnetic field strength. We find that the transition between these two regimes is obtained when the ion cyclotron frequency equals the ion-neutrals collision frequency. This is in agreement with the theory of the slow-ion drift instability induced by the collisional slowing of the electric ion drift (A. Simon, Phys. Fluids 6, 382, (1963). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.06125v1.pdf"}
{"id": "1602.06849", "abstract": "  Solvable supersymmetric algebraic model for descriptions of the spherical to gama unstable shape- phase transition in even and odd mass nuclei is proposed. This model is based on dual algebraic structure and Richardson - Gaudin method, where the duality relations between the unitary and quasispin algebraic structures for the boson and fermion systems are extended to mixed boson- fermion system. The structure of two type of nuclear supersymmetry schemes, based on the U(6/2) and U(6/4) supergroups, is discussed. We investigate the change in level structure induced by the phase transition by doing a quantal analysis. By using the generalized quasispin algebra, it is shown that the nuclear supersymmetry concept can be also used for transitional regions in addition to dynamical symmetry limits. Experimental evidence for the U(5)-O(6) transition in Ru-Rh and Zn- Cu supermultiplets is presented. The low-states energy spectra and B(E2)values for these nuclei have been calculated and compared with the experimental data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.06849v1.pdf"}
{"id": "1602.06877", "abstract": "  We present first-principles calculations of metallic atomic hydrogen in the 400-600 GPa pressure range in a tetragonal structure with space group I4_1/amd, which is predicted to be its first atomic phase. Our calculations show a band structure close to the free-electron-like limit due to the high electronic kinetic energy induced by pressure. Bands are properly described even in the independent electron approximation fully neglecting the electron-electron interaction. Linear-response harmonic calculations show a dynamically stable phonon spectrum with marked Kohn anomalies. Even if the electron-electron interaction has a minor role in the electronic bands, the inclusion of electronic ex- change and correlation in the density response is essential to obtain a dynamically stable structure. Anharmonic effects, which are calculated within the stochastic self-consistent harmonic approxima- tion, harden high-energy optical modes and soften transverse acoustic modes up to a 20", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.06877v1.pdf"}
{"id": "1603.02436", "abstract": "  In the single-scattering theory of electromagnetic radiation, the fractal regime is a definite range in the photon momentum-transfer q, which is characterized by the scaling-law behavior of the structure factor: S(q) ∝ 1/q^d_f. This allows a straightforward estimation of the fractal dimension d_f of aggregates in Small-Angle X-ray Scattering (SAXS) experiments. However, this behavior is not commonly studied in optical scattering experiments because of the lack of information on its domain of validity. In the present work, we propose a definition of the multiple-scattering structure factor, which naturally generalizes the single-scattering function S(q). We show that the mean-field theory of electromagnetic scattering provides an explicit condition to interpret the significance of multiple scattering. In this paper, we investigate and discuss electromagnetic scattering by three classes of fractal aggregates. The results obtained from the TMatrix method show that the fractal scaling range is divided into two domains: 1) a genuine fractal regime, which is robust; 2) a possible anomalous scaling regime, S(q) ∝ 1/q^δ, with exponent δ independent of d_f, and related to the way the scattering mechanism uses the local morphology of the scatterer. The recognition, and an analysis, of the latter domain is of importance because it may result in significant reduction of the fractal regime, and brings into question the proper mechanism in the build-up of multiple-scattering. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.02436v1.pdf"}
{"id": "1603.03122", "abstract": "  The role of the side channels in the continuous-variable quantum key distribution is studied. It is shown how the information leakage through a side channel from the trusted sender station increases the vulnerability of the protocols to the eavesdropping in the main quantum communication channel. Moreover, the untrusted noise infusion by an eavesdropper on the trusted receiving side breaks the security even for a purely attenuating main quantum channel. As a method to compensate for the effect of the side-channel leakage on the sender side, we suggest several types of manipulations on the side-channel input. It is shown that by applying the modulated coherent light on the input of the side channel that is optimally correlated to the modulation on the main signal and optionally, introducing additional squeezing in the case of the squeezed-state protocol, the negative influence of the lossy side channel on the sender side can be completely removed. For the trusted receiving side, the method of optimal monitoring of the residual noise from the side-channel noise infusion is suggested and shown to be able to completely eliminate the presence of the noisy side channel. We therefore prove that the side-channel effects can be completely removed using feasible operations if the trusted parties access the respective parts of the side channels. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.03122v1.pdf"}
{"id": "1603.03476", "abstract": "  We study the infrared dynamics of low-energy atoms interacting with a sample of suspended graphene at finite temperature. The dynamics exhibits severe infrared divergences order by order in perturbation theory as a result of the singular nature of low-energy flexural phonon emission. Our model can be viewed as a two-channel generalization of the independent boson model with asymmetric atom-phonon coupling. This allows us to take advantage of the exact non-perturbative solution of the independent boson model in the stronger channel while treating the weaker one perturbatively. In the low-energy limit, the exact solution can be viewed as a resummation (exponentiation) of the most divergent diagrams in the perturbative expansion. As a result of this procedure, we obtain the atom's Green function which we use to calculate the atom damping rate, a quantity equal to the quantum sticking rate. A characteristic feature of our results is that the Green's function retains a weak, infrared cutoff dependence that reflects the reduced dimensionality of the problem. As a consequence, we predict a measurable dependence of the sticking rate on graphene sample size. We provide detailed predictions for the sticking rate of atomic hydrogen as a function of temperature and sample size. The resummation yields an enhanced sticking rate relative to the conventional Fermi golden rule result (equivalent to the one-loop atom self-energy), as higher-order processes increase damping at finite temperature. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.03476v2.pdf"}
{"id": "1603.03495", "abstract": "  Molecular Communication as the most potential methods to solve the communication in nano scale, for it's derived from nature, and it becomes more and more prevalent. Though molecular communication happens in three dimensional situation, there are also some situation that are in the one dimensional situation, especially when considering the transmitters and the receivers are in extremely short distance or in long slim pipe. In this paper, we introduce the one dimensional situation, and studied how the continuous information molecules transmitted in this situation, also introduced how to encode and decode the information molecules, and based on the molecular communication model, we studied some metrics of it, such as the distance between transmitter and receiver, the emitting frequency of transmitter. Through the research we know that the distance and frequency are important metrics to the successful communication, which can direct us how to place the nano transmitters and receivers in the future nano network environment. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.03495v1.pdf"}
{"id": "1603.06318", "abstract": "  Combining deep neural networks with structured logic rules is desirable to harness flexibility and reduce uninterpretability of the neural models. We propose a general framework capable of enhancing various types of neural networks (e.g., CNNs and RNNs) with declarative first-order logic rules. Specifically, we develop an iterative distillation method that transfers the structured information of logic rules into the weights of neural networks. We deploy the framework on a CNN for sentiment analysis, and an RNN for named entity recognition. With a few highly intuitive rules, we obtain substantial improvements and achieve state-of-the-art or comparable results to previous best-performing systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.06318v6.pdf"}
{"id": "1603.06381", "abstract": "  This paper considers uncertainty quantification for an elliptic nonlocal equation. In particular, it is assumed that the parameters which define the kernel in the nonlocal operator are uncertain and a priori distributed according to a probability measure. It is shown that the induced probability measure on some quantities of interest arising from functionals of the solution to the equation with random inputs is well-defined; as is the posterior distribution on parameters given observations. As the elliptic nonlocal equation cannot be solved approximate posteriors are constructed. The multilevel Monte Carlo (MLMC) and multilevel sequential Monte Carlo (MLSMC) sampling algorithms are used for a priori and a posteriori estimation, respectively, of quantities of interest. These algorithms reduce the amount of work to estimate posterior expectations, for a given level of error, relative to Monte Carlo and i.i.d. sampling from the posterior at a given level of approximation of the solution of the elliptic nonlocal equation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.06381v1.pdf"}
{"id": "1603.07087", "abstract": "  We present a novel automatic adaptive aperture photometry algorithm for measuring the total magnitudes of merging galaxies with irregular shapes. First, we use a morphological pattern recognition routine for identifying the shape of an irregular source in a background-subtracted image. Then, we extend the shape of the source by using the Dilation image operation to obtain an aperture that is quasi-homomorphic to the shape of the irregular source. The magnitude measured from the homomorphic aperture would thus have minimal contamination from the nearby background. As a test of our algorithm, we applied our technique to the merging galaxies observed by the Sloan Digital Sky Survey (SDSS) and the Canada-France-Hawaii Telescope (CFHT). Our results suggest that the adaptive homomorphic aperture algorithm can be very useful for investigating extended sources with irregular shapes and sources in crowded regions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.07087v1.pdf"}
{"id": "1603.07605", "abstract": "  Quantum key distribution using three states in equiangular configuration combines a security threshold comparable with the one of the Bennett-Brassard 1984 protocol and a quantum bit error rate (QBER) estimation that does not need to reveal part of the key. We implement an entanglement-based version of the Renes 2004 protocol, using only passive optic elements in a linear scheme for the measurement POVM, generating an asymptotic secure key rate of more than 10 kbit/s, with a mean QBER of 1.6", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.07605v1.pdf"}
{"id": "1603.08921", "abstract": "  It has been proposed that mixing induced by convective overshoot can disrupt the inward propagation of carbon deflagrations in super-asymptotic giant branch stars. To test this theory, we study an idealized model of convectively bounded carbon flames with 3D hydrodynamic simulations of the Boussinesq equations using the pseudospectral code Dedalus. Because the flame propagation timescale is much longer than the convection timescale, we approximate the flame as fixed in space, and only consider its effects on the buoyancy of the fluid. By evolving a passive scalar field, we derive a turbulent chemical diffusivity produced by the convection as a function of height, D_ t(z). Convection can stall a flame if the chemical mixing timescale, set by the turbulent chemical diffusivity, D_ t, is shorter than the flame propagation timescale, set by the thermal diffusivity, κ, i.e., when D_ t>κ. However, we find D_ t<κ for most of the flame because convective plumes are not dense enough to penetrate into the flame. Extrapolating to realistic stellar conditions, this implies that convective mixing cannot stall a carbon flame and that \"hybrid carbon-oxygen-neon\" white dwarfs are not a typical product of stellar evolution. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.08921v2.pdf"}
{"id": "1603.09602", "abstract": "  The behavior of the average velocity, its deviation and average squared velocity are characterized using three techniques for a 1-D dissipative impact system. The system – a particle, or an ensemble of non interacting particles, moving in a constant gravitation field and colliding with a varying platform – is described by a nonlinear mapping. The average squared velocity allows to describe the temperature for an ensemble of particles as a function of the parameters using: (i) straightforward numerical simulations; (ii) analytically from the dynamical equations; (iii) using the probability distribution function. Comparing analytical and numerical results for the three techniques, one can check the robustness of the developed formalism, where we are able to estimate numerical values for the statistical variables, without doing extensive numerical simulations. Also, extension to other dynamical systems is immediate, including time dependent billiards. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.09602v1.pdf"}
{"id": "1603.09629", "abstract": "  Two popular types of spacecraft actuators are reaction wheels and magnetic torque coils. Magnetic torque coils are particularly interesting because they can be used for both attitude control and reaction wheel momentum management (desaturation control). Although these two tasks are performed at the same time using the same set of actuators, most design methods deal with only one of the these tasks or consider these two tasks separately. In this paper, a design with these two tasks in mind is formulated as a single problem. A periodic time-varying linear quadratic regulator design method is then proposed to solve this problem. A simulation example is provided to describe the benefit of the new strategy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.09629v2.pdf"}
{"id": "1604.01817", "abstract": "  We extend the semiclassical theory of short periodic orbits [Phys. Rev. E 80, 035202(R) (2009)] to partially open quantum maps. They correspond to classical maps where the trajectories are partially bounced back due to a finite reflectivity R. These maps are representative of a class that has many experimental applications. The open scar functions are conveniently redefined, providing a suitable tool for the investigation of these kind of systems. Our theory is applied to the paradigmatic partially open tribaker map. We find that the set of periodic orbits that belong to the classical repeller of the open map (R=0) are able to support the set of long-lived resonances of the partially open quantum map in a perturbative regime. By including the most relevant trajectories outside of this set, the validity of the approximation is extended to a broad range of R values. Finally, we identify the details of the transition from qualitatively open to qualitatively closed behaviour, providing an explanation in terms of short periodic orbits. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.01817v1.pdf"}
{"id": "1604.01921", "abstract": "  The FCAL collaboration is preparing large scale prototypes of special calorimeters to be used in the very forward region at a future linear electron positron collider for a precise and fast luminosity measurement and beam-tuning. These calorimeters are designed as sensor-tungsten calorimeters with very thin sensor planes to keep the Moliere radius small and dedicated FE electronics to match the timing and dynamic range requirements. A partially instrumented prototype was investigated in the CERN PS T9 beam in 2014 and at the DESY-II Synchrotron in 2015. It was operated in a mixed particle beam (electrons, muons and hadrons) of 5 GeV from PS facilities and with secondary electrons of 5 GeV energy from DESY-II. The results demonstrated a very good performance of the full readout chain. The high statistics data were used to study the response to different particles, perform sensor alignment and measure the longitudinal shower development in the sandwich. In addition, Geant4 MC simulations were done, and compared to the data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.01921v1.pdf"}
{"id": "1604.03107", "abstract": "  The origin of Jupiter-mass planets with orbital periods of only a few days is still uncertain. It is widely believed that these planets formed near the water-ice line of the protoplanetary disk, and subsequently migrated into much smaller orbits. Most of the proposed migration mechanisms can be classified either as disk-driven migration, or as excitation of a very high eccentricity followed by tidal circularization. In the latter scenario, the giant planet that is destined to become a hot Jupiter spends billions of years on a highly-eccentric orbit, with apastron near the water-ice line. Eventually, tidal dissipation at periastron shrinks and circularizes the orbit. If this is correct, then it should be especially rare for hot Jupiters to be accompanied by another giant planet interior to the water-ice line. Using the current sample of giant planets discovered with the Doppler technique, we find that hot Jupiters with P_orb < 10 days are no more or less likely to have exterior Jupiter-mass companions than longer-period giant planets with P_orb >= 10 days. This result holds for exterior companions both inside and outside of the approximate location of the water-ice line. These results are difficult to reconcile with the high-eccentricity migration scenario for hot Jupiter formation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.03107v1.pdf"}
{"id": "1604.03314", "abstract": "  In this paper we describe the current status of the CALDER project, which is developing ultra-sensitive light detectors based on superconductors for cryogenic applications. When we apply an AC current to a superconductor, the Cooper pairs oscillate and acquire kinetic inductance, that can be measured by inserting the superconductor in a LC circuit with high merit factor. Interactions in the superconductor can break the Cooper pairs, causing sizable variations in the kinetic inductance and, thus, in the response of the LC circuit. The continuous monitoring of the amplitude and frequency modulation allows to reconstruct the incident energy with excellent sensitivity. This concept is at the basis of Kinetic Inductance Detectors (KIDs), that are characterized by natural aptitude to multiplexed read-out (several sensors can be tuned to different resonant frequencies and coupled to the same line), resolution of few eV, stable behavior over a wide temperature range, and ease in fabrication. We present the results obtained by the CALDER collaboration with 2x2 cm2 substrates sampled by 1 or 4 Aluminum KIDs. We show that the performances of the first prototypes are already competitive with those of other commonly used light detectors, and we discuss the strategies for a further improvement. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.03314v1.pdf"}
{"id": "1604.03472", "abstract": "  We present a general framework for deriving effective spin Hamiltonians of correlated magnetic systems based on a combination of relativistic ab initio density functional theory calculations (DFT), exact diagonalization of a generalized Hubbard Hamiltonian on finite clusters and spin projections onto the low-energy subspace. A key motivation is to determine anisotropic bilinear exchange couplings in materials of interest. As an example, we apply this method to the pyrochlore Lu_2V_2O_7 where the vanadium ions form a lattice of corner-sharing spin-1/2 tetrahedra. In this compound, anisotropic Dzyaloshinskii-Moriya interactions (DMI) play an essential role in inducing a magnon Hall effect. We obtain quantitative estimates of the nearest-neighbor Heisenberg exchange, the DMI, and the symmetric part of the anisotropic exchange tensor. Finally, we compare our results with experimental ones on the Lu_2V_2O_7 compound. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.03472v1.pdf"}
{"id": "1604.04216", "abstract": "  We investigate the transport properties of Chern insulators following a quantum quench between topological and non-topological phases. Recent works have shown that this yields an excited state for which the Chern number is preserved under unitary evolution. However, this does not imply the preservation of other physical observables, as we stressed in our previous work. Here we provide an analysis of the Hall response following a quantum quench in an isolated system, with explicit results for the Haldane model. We show that the Hall conductance is no longer related to the Chern number in the post-quench state, in agreement with previous work. We also examine the dynamics of the edge currents in finite-size systems with open boundary conditions along one direction. We show that the late-time behavior is captured by a Generalized Gibbs Ensemble, after multiple traversals of the sample. We discuss the effects of generic open boundary conditions and confinement potentials. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.04216v2.pdf"}
{"id": "1604.04988", "abstract": "  The solar corona is the origin of very dynamic events that are mostly produced in active regions (AR) and coronal holes (CH). The exact location of these large-scale features can be determined by applying image-processing approaches to extreme-ultraviolet (EUV) data.   We here investigate the problem of segmentation of solar EUV images into ARs, CHs, and quiet-Sun (QS) images in a firm Bayesian way. On the basis of Bayes' rule, we need to obtain both prior and likelihood models. To find the prior model of an image, we used a Potts model in non-local mode. To construct the likelihood model, we combined a mixture of a Markov-Gauss model and non-local means. After estimating labels and hyperparameters with the Gibbs estimator, cellular learning automata were employed to determine the label of each pixel.   We applied the proposed method to a Solar Dynamics Observatory/ Atmospheric Imaging Assembly (SDO/AIA) dataset recorded during 2011 and found that the mean value of the filling factor of ARs is 0.032 and 0.057 for CHs. The power-law exponents of the size distribution of ARs and CHs were obtained to be -1.597 and -1.508, respectively, with the maximum likelihood estimator method. When we compare the filling factors of our method with a manual selection approach and the SPoCA algorithm, they are highly compatible. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.04988v1.pdf"}
{"id": "1604.05062", "abstract": "  We investigate anomalies in liquid silica with molecular dynamics simulations and present evidence for a fragile-to-strong transition at around 3100 K-3300 K. To this purpose, we studied the structure and dynamical properties of silica over a wide temperature range, finding four indicators of a fragile-to-strong transition. First, there is a density minimum at around 3000 K and a density maximum at 4700 K. The turning point is at 3400 K. Second, the local structure characterized by the tetrahedral order parameter changes dramatically around 3000 K from a higher-ordered, lower-density phase to a less ordered, higher-density phase. Third, the correlation time τ changes from an Arrhenius behavior below 3300 K to a Vogel-Fulcher-Tammann behavior at higher temperatures. Fourth, the Stokes-Einstein relation holds for temperatures below 3000 K, but is replaced by a fractional relation above this temperature. Furthermore, our data indicate that dynamics become again simple above 5000 K, with Arrhenius behavior and a classical Stokes-Einstein relation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.05062v1.pdf"}
{"id": "1604.07742", "abstract": "  We present a general formulation to analyze the structure of slowly rotating relativistic stars in a broad class of scalar-tensor theories with disformal coupling to matter. Our approach includes theories with generalized kinetic terms, generic scalar field potentials and contains theories with conformal coupling as particular limits. In order to investigate how the disformal coupling affects the structure of relativistic stars, we propose a minimal model of a massless scalar-tensor theory and investigate in detail how the disformal coupling affects the spontaneous scalarization of slowly rotating neutron stars. We show that for negative values of the disformal coupling parameter between the scalar field and matter, scalarization can be suppressed, while for large positive values of the disformal coupling parameter stellar models cannot be obtained. This allows us to put a mild upper bound on this parameter. We also show that these properties can be qualitatively understood by linearizing the scalar field equation of motion in the background of a general-relativistic incompressible star. To address the intrinsic degeneracy between uncertainties in the equation-of-state of neutron stars and gravitational theory, we also show the existence of universal equation-of-state-independent relations between the moment of inertia and compactness of neutron stars in this theory. We show that in a certain range of the theory's parameter space the universal relation largely deviates from that of general relativity, allowing, in principle, to probe the existence of spontaneous scalarization with future observations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.07742v2.pdf"}
{"id": "1604.08109", "abstract": "  A water-filled differentially heated rotating annulus with initially prepared stable vertical salinity profiles is studied in the laboratory. Based on two-dimensional horizontal particle image velocimetry (PIV) data, and infrared camera visualizations, we describe the appearance and the characteristics of the baroclinic instability in this original configuration. First, we show that when the salinity profile is linear and confined between two non stratified layers at top and bottom, only two separate shallow fluid layers can be destabilized. These unstable layers appear nearby the top and the bottom of the tank with a stratified motionless zone between them. This laboratory arrangement is thus particularly interesting to model geophysical or astrophysical situations where stratified regions are often juxtaposed to convective ones. Then, for more general but stable initial density profiles, statistical measures are introduced to quantify the extent of the baroclinic instability at given depths and to analyze the connections between this depth-dependence and the vertical salinity profiles. We find that, although the presence of stable stratification generally hinders full-depth overturning, double-diffusive convection can yield development of multicellular sideways convection in shallow layers and subsequently to a multilayered baroclinic instability. Therefore we conclude that by decreasing the characteristic vertical scale of the flow, stratification may even enhance the formation of cyclonic and anticyclonic eddies (and thus, mixing) in a local sense. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.08109v1.pdf"}
{"id": "1604.08846", "abstract": "  This paper discusses several (sub)gradient methods attaining the optimal complexity for smooth problems with Lipschitz continuous gradients, nonsmooth problems with bounded variation of subgradients, weakly smooth problems with Hölder continuous gradients. The proposed schemes are optimal for smooth strongly convex problems with Lipschitz continuous gradients and optimal up to a logarithmic factor for nonsmooth problems with bounded variation of subgradients. More specifically, we propose two estimation sequences of the objective and give two iterative schemes for each of them. In both cases, the first scheme requires the smoothness parameter and the Hölder constant, while the second scheme is parameter-free (except for the strong convexity parameter which we set zero if it is not available) at the price of applying a nonmonotone backtracking line search. A complexity analysis for all the proposed schemes is given. Numerical results for some applications in sparse optimization and machine learning are reported, which confirm the theoretical foundations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.08846v1.pdf"}
{"id": "1605.00958", "abstract": "  We consider a periodic array of graphene nanoribbons under the action of a strong dc electric field E_0 and an external electromagnetic excitation with the frequency ω and the lateral wave vector q. Solving the quasi-classical Boltzmann kinetic equation and calculating the surface dynamic conductivity σ_2D(q,ω,E_0) and the absorption coefficient of such a system we show that the real part of the conductivity and the absorption coefficient may become negative under certain conditions. Physically this corresponds to the amplification of the electromagnetic waves at the expense of the energy of the direct current source. The results are discussed in connection with experiments on the surface acoustic waves and on the Smith-Purcell-type graphene-based terahertz emitter. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.00958v2.pdf"}
{"id": "1605.01150", "abstract": "  A method is proposed to identify target states that optimize a metastability index amongst a set of trial states and use these target states as milestones (or core sets) to build Markov State Models (MSMs). If the optimized metastability index is small, this automatically guarantees the accuracy of the MSM, in the sense that the transitions between the target milestones is indeed approximately Markovian. The method is simple to implement and use, it does not require that the dynamics on the trial milestones be Markovian, and it also offers the possibility to partition the system's state-space by assigning every trial milestone to the target milestones it is most likely to visit next and to identify transition state regions. Here the method is tested on the Gly-Ala-Gly peptide, where it shown to correctly identify the expected metastable states in the dihedral angle space of the molecule without a priori information about these states. It is also applied to analyze the folding landscape of the Beta3s mini-protein, where it is shown to identify the folded basin as a connecting hub between an helix-rich region, which is entropically stabilized, and a beta-rich region, which is energetically stabilized and acts as a kinetic trap. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.01150v2.pdf"}
{"id": "1605.04925", "abstract": "  Host galaxy properties provide strong constraints on the stellar progenitors of superluminous supernovae. By comparing a sample of 19 low-redshift (z < 0.3) superluminous supernova hosts to galaxy populations in the local Universe, we show that sub-solar metallicities seem to be a requirement. All superluminous supernovae in hosts with high measured gas-phase metallicities are found to explode at large galactocentric radii, indicating that the metallicity at the explosion site is likely lower than the integrated host value. We found that superluminous supernovae hosts do not always have star-formation rates higher than typical star-forming galaxies of the same mass. However, we confirm that high absolute specific star-formation rates are a feature of superluminous supernova host galaxies, but interpret this as simply a consequence of the anti-correlation between gas-phase metallicity and specific star-formation rate and the requirement of on-going star formation to produce young, massive stars greater than   10-20 M_sol. Based on our sample, we propose an upper limit of   0.5 Z_sol for forming superluminous supernova progenitors (assuming an N2 metallicity diagnostic and a solar oxygen abundance of 8.69). Finally, we show that if magnetar powering is the source of the extreme luminosity then the required initial spins appear to be correlated with metallicity of the host galaxy. This correlation needs further work, but if it holds it is a powerful link between the supernova parameters and nature of the progenitor population. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.04925v3.pdf"}
{"id": "1605.05037", "abstract": "  We study the problem of managing interference in linear networks, with backhaul constraints that admit centralized allocation of messages to transmitters through the cloud. Our setting is that of a generic channel, where no channel state information is available at the transmitters. Knowing only the network topology, we characterize the optimal decisions for assigning messages to transmitters, given that each receiver is interested in one message that can be available at N transmitters. We show that using linear cooperation schemes, the per user degrees of freedom does not increase as we increase N beyond unity. Hence, we conclude for the considered problem that linear cooperative transmission does not increase the degrees of freedom. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.05037v1.pdf"}
{"id": "1605.05908", "abstract": "  For finite-dimensional quantum systems, such as qubits, a well established strategy to protect such systems from decoherence is dynamical decoupling. However many promising quantum devices, such as oscillators, are infinite dimensional, for which the question if dynamical decoupling could be applied remained open. Here we first show that not every infinite-dimensional system can be protected from decoherence through dynamical decoupling. Then we develop dynamical decoupling for continuous variable systems which are described by quadratic Hamiltonians. We identify a condition and a set of operations that allow us to map a set of interacting harmonic oscillators onto a set of non-interacting oscillators rotating with an averaged frequency, a procedure we call homogenization. Furthermore we show that every quadratic system-environment interaction can be suppressed with two simple operations acting only on the system. Using a random dynamical decoupling or homogenization scheme, we develop bounds that characterize how fast we have to work in order to achieve the desired uncoupled dynamics. This allows us to identify how well homogenization can be achieved and decoherence can be suppressed in continuous variable systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.05908v2.pdf"}
{"id": "1605.06132", "abstract": "  In this paper, we construct a generalized recursive Darboux transformation of a focusing vector nonlinear Schrödinger equation known as the Manakov system. We apply this generalized recursive Darboux transformation to the Lax-pairs of this system in view of generating the Nth-order vector generalization rogue wave solutions with the same spectral parameter through a direct iteration rule. As a result, we discuss the first, second and third-order vector generalization rogue wave solutions while illustrating these features with some depictions. We show that higher-order rogue wave solutions depend on the values of their free parameters. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.06132v1.pdf"}
{"id": "1605.08566", "abstract": "  We present a quantum theory for a fully coupled hybrid optomechanical system where all mutual couplings between a two-level atom, a confined photon mode and a mechanical oscillator mode are considered. In such a configuration, new quantum interference effects and correlations arise due to the interplay and competition between the different physical interactions. We present an analytical diagonalization of the related fully coupled Hamiltonian, showing the nature and energy spectra of the tripartite dressed excitations. We determine the driven-dissipative dynamics of such hybrid systems and study phonon blockade effects under resonant excitation. We also study the statistical properties of the photon emission obtained under incoherent pumping of the two-level atom, which is particularly relevant for experiments with solid-state two-level emitters. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.08566v1.pdf"}
{"id": "1605.09054", "abstract": "  This paper is aimed at investigating a 5D holographic dark energy in DGP-BRANE cosmology by employing a combination of Sne Ia, BAO and CMB observational data to fit the cosmological parameters in the model. We describe the dynamic of a FRW for the normal branch (ϵ = +1) of solutions of the induced gravity brane-world model. We take the matter in 5D bulk as holographic dark energy that its holographic nature is reproduced effectively in 4D. The cosmic evolution reveals that the effective 4D holographic dark energy behaves as quintessence while taking into account the 4D cold dark matter results in matter dominated universe followed by late time acceleration. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.09054v2.pdf"}
{"id": "1606.00548", "abstract": "  This paper presents our work on simulation of large-scale reservoir models on IBM Blue Gene/Q and studying the scalability of our parallel reservoir simulators. An in-house black oil simulator has been implemented. It uses MPI for communication and is capable of simulating reservoir models with hundreds of millions of grid cells. Benchmarks show that our parallel simulator are thousands of times faster than sequential simulators that designed for workstations and personal computers, and the simulator has excellent scalability. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.00548v1.pdf"}
{"id": "1606.00712", "abstract": "  The main goal of galaxy surveys is to map the distribution of the galaxies, for the purpose of understanding the properties of this distribution and its implications for the content and evolution of the universe. However, in order to realise the potential of these surveys, we need to ensure that we are using the correct analysis: the relativistic analysis, which has been widely studied recently. In this work, the known relativistic overdensity of galaxy surveys is re-examined. Subtle, yet crucial parameters which appear to have been missed by previous works are uncovered. The possible implication of these parameters on the observed galaxy power spectrum is demonstrated for a generic survey, in the cosmological concordance model. The results show that these parameters can alter the predictions of galaxy clustering on all scales; hence, the relativistic effects (on ultra-large scales). In particular, the results show that ignoring these parameters - as in the analysis in previous works - will lead to a false overestimation of the galaxy clustering strength in structure formation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.00712v4.pdf"}
{"id": "1606.01314", "abstract": "  In wireless cloud storage systems, the recovery failure probability depends on not only wireless channel conditions but also storage size of each distributed storage node. For an efficient utilization of limited storage capacity and the performance characterization of allocation strategies, we asymptotically analyze the recovery failure probability of a wireless cloud storage system with a sum storage capacity constraint for both high SNR regime and low SNR regime. Then, we find the optimal storage allocation strategy across distributed storage nodes in terms of the asymptotic recovery failure probability. Our analysis reveals that the maximal symmetric allocation is optimal for high SNR regime and the minimal allocation (with ⌊ T⌋ complete storage nodes and an incomplete storage node) is optimal for low SNR regime, where T is the sum storage capacity. Based on the numerical investigation, we also show that in intermediate SNR regime, a balance allocation between the minimal allocation and the maximal symmetric allocation would not be required if we select one between them according to SNR. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.01314v1.pdf"}
{"id": "1606.01676", "abstract": "  This paper investigates the potential to detect tau neutrinos in the energy range of 1-1000 PeV searching for very inclined showers with imaging Cherenkov telescopes. A neutrino induced tau lepton escaping from the Earth may decay and initiate an air shower which can be detected by a fluorescence or Cherenkov telescope. We present here a study of the detection potential of Earth-skimming neutrinos taking into account neutrino interactions in the Earth crust, local matter distributions at various detector sites, the development of tau-induced showers in air and the detection of Cherenkov photons with IACTs. We analyzed simulated shower images on the camera focal plane and implemented generic reconstruction chains based on Hillas parameters. We find that present IACTs can distinguish air showers induced by tau neutrinos from the background of hadronic showers in the PeV-EeV energy range. We present the neutrino trigger efficiency obtained for a few configurations being considered for the next-generation Cherenkov telescopes, i.e. the Cherenkov Telescope Array. Finally, for a few representative neutrino spectra expected from astrophysical sources, we compare the expected event rates at running IACTs to what is expected for the dedicated IceCube neutrino telescope. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.01676v1.pdf"}
{"id": "1606.02959", "abstract": "  Volumetric spline parameterization and computational efficiency are two main challenges in isogeometric analysis (IGA). To tackle this problem, we propose a framework of computation reuse in IGA on a set of three-dimensional models with similar semantic features. Given a template domain, B-spline based consistent volumetric parameterization is first constructed for a set of models with similar semantic features. An efficient quadrature-free method is investigated in our framework to compute the entries of stiffness matrix by Bezier extraction and polynomial approximation. In our approach, evaluation on the stiffness matrix and imposition of the boundary conditions can be pre-computed and reused during IGA on a set of CAD models. Examples with complex geometry are presented to show the effectiveness of our methods, and efficiency similar to the computation in linear finite element analysis can be achieved for IGA taken on a set of models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.02959v3.pdf"}
{"id": "1606.05484", "abstract": "  Recent studies have dealt with the electronic and magnetic ground state properties of the tetraboride material MnB_4. So far, however, the ground state properties could not be established unambiguously. Therefore, here we present an experimental study on single-crystalline MnB_4 by means of resistivity and magnetization measurements. For this, we have developed a sample holder that allows four-point ac resistivity measurements on these very small (∼ 100 μm) samples. With our data we establish that the electronic ground state of MnB_4 is intrinsically that of a pseudo-gap system, in agreement with recent band structure calculations. Furthermore, we demonstrate that the material does neither show magnetic order nor a behavior arising from the vicinity to a magnetically ordered state, this way disproving previous claims. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.05484v3.pdf"}
{"id": "1606.06040", "abstract": "  We investigate the properties of the stellar populations of model galaxies as a function of galaxy evolutionary history and angular momentum content. We use the new semi-analytic model presented in Tonini et al. (2016). This new model follows the angular momentum evolution of gas and stars, providing the base for a new star formation recipe, and treatment of the effects of mergers that depends on the central galaxy dynamical structure. We find that the new recipes have the effect of boosting the efficiency of the baryonic cycle in producing and recycling metals, as well as preventing minor mergers from diluting the metallicity of bulges and ellipticals. The model reproduces the stellar mass - stellar metallicity relation for galaxies above 1e10 solar masses, including Brightest Cluster Galaxies. Model disks, galaxies dominated by instability-driven components, and merger-driven objects each stem from different evolutionary channels. These model galaxies therefore occupy different loci in the galaxy mass-size relation, which we find to be in accord with the Atlas 3D classification of disk galaxies, fast rotators and slow rotators. We find that the stellar populations' properties depend on the galaxy evolutionary type, with more evolved stellar populations being part of systems that have lost or dissipated more angular momentum during their assembly history. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.06040v2.pdf"}
{"id": "1606.06462", "abstract": "  We investigate the ground-state properties of a disorderd Ising model with uniform transverse field on the Bethe lattice, focusing on the quantum phase transition from a paramagnetic to a glassy phase that is induced by reducing the intensity of the transverse field. We use a combination of quantum Monte Carlo algorithms and exact diagonalization to compute Rényi entropies, quantum Fisher information, correlation functions and order parameter. We locate the transition by means of the peak of the Rényi entropy and we find agreement with the transition point estimated from the emergence of finite values of the Edwards-Anderson order parameter and from the peak of the correlation length. We interpret the results by means of a mean-field theory in which quantum fluctuations are treated as massive particles hopping on the interaction graph. We see that the particles are delocalized at the transition, a fact that points towards the existence of possibly another transition deep in the glassy phase where these particles localize, therefore leading to a many-body localized phase. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.06462v1.pdf"}
{"id": "1606.06476", "abstract": "  Currently, one of the hottest topics in the Internet of Things (IoT) research domain regards the issue to overcome the heterogeneity of proprietary technologies and systems so as to enable the integration of applications and devices developed for different environments in a single interoperable framework. Towards this objective, virtualization is widely used to foster integration and creation of new services and applications. Similar benefits are expected by its application in the smart grid arena. The use of a virtualization middleware is expected to enrich the capabilities and opportunities related to the use of smart grid devices. In this paper, we propose key features for an interoperable, re-usable, elastic and secure smart grid architecture which is cloud-based and relies on REST APIs. To highlight the benefits, a practical case study is presented, where outlined functionalities are implemented in a cloud-based IoT platform. The advantages brought by the proposed middleware in terms of interoperability, re-usability, privacy and elasticity of the underlying infrastructure are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.06476v2.pdf"}
{"id": "1606.06559", "abstract": "  The speciation model proposed by Derrida and Higgs demonstrated that a sexually reproducing population can split into different species in the absence of natural selection or any type of geographic isolation, provided that mating is assortative and the number of genes involved in the process is infinite. Here we revisit this model and simulate it for finite genomes, focusing on the question of how many genes it actually takes to trigger neutral sympatric speciation. We find that, for typical parameters used in the original model, it takes of the order of 10^5 genes. We compare the results with a similar spatially explicit model where about 100 genes suffice for speciation. We show that when the number of genes is small the species that emerge are strongly segregated in space. For larger number of genes, on the other hand, the spatial structure of the population is less important and the species distribution overlap considerably. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.06559v2.pdf"}
{"id": "1606.06688", "abstract": "  In recent quantum optical continuous-variable experiments, the number of fully inseparable light modes has drastically increased by introducing a multiplexing scheme either in the time domain or in the frequency domain. Here, modifying the time-domain multiplexing experiment reported in Nature Photonics 7, 982 (2013), we demonstrate successive generation of fully inseparable light modes for more than one million modes. The resulting multi-mode state is useful as a dual-rail CV cluster state. We circumvent the previous problem of optical phase drifts, which has limited the number of fully inseparable light modes to around ten thousands, by continuous feedback control of the optical system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.06688v1.pdf"}
{"id": "1606.07954", "abstract": "  Recent work on jets and disk winds in low-mass X-ray binaries (LMXBs) suggests that they are to a large extent mutually exclusive, with jets observed in spectrally hard states and disk winds observed in spectrally soft states. In this paper we use existing literature on jets and disk winds in the luminous neutron star (NS) LMXB GX 13+1, in combination with archival Rossi X-ray Timing Explorer data, to show that this source is likely able to produce jets and disk winds simultaneously. We find that jets and disk winds occur in the same location on the source's track in its X-ray color-color diagram. A further study of literature on other luminous LMXBs reveals that this behavior is more common, with indications for simultaneous jets and disk winds in the black hole LMXBs V404 Cyg and GRS 1915+105 and the NS LMXBs Sco X-1 and Cir X-1. For the three sources for which we have the necessary spectral information, we find that the simultaneous jets/winds all occur in their spectrally hardest states. Our findings indicate that in LMXBs with luminosities above a few tens of percent of the Eddington luminosity, jets and disk winds are not mutually exclusive, and that the presence of disk winds does not necessarily result in jet suppression. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.07954v2.pdf"}
{"id": "1606.08721", "abstract": "  We introduce delays in a tuberculosis (TB) model, representing the time delay on the diagnosis and commencement of treatment of individuals with active TB infection. The stability of the disease free and endemic equilibriums is investigated for any time delay. Corresponding optimal control problems, with time delays in both state and control variables, are formulated and studied. Although it is well-known that there is a delay between two to eight weeks between TB infection and reaction of body's immune system to tuberculin, delays for the active infected to be detected and treated, and delays on the treatment of persistent latent individuals due to clinical and patient reasons, which clearly justifies the introduction of time delays on state and control measures, our work seems to be the first to consider such time-delays for TB and apply time-delay optimal control to carry out the optimality analysis. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.08721v1.pdf"}
{"id": "1606.09120", "abstract": "  We present an apparatus that converts every pulse of a pulsed light source to a pulse train in which the intensities of the different pulses are samples of the spatial or temporal frequency spectrum of the original pulse. In this way, the spectrum of the incident light can be measured by following the temporal response of a single detector. The apparatus is based on multiple round-trips inside a 2f- cavity-like mirror arrangement in which the spectrum is spread on the back focal plane, where after each round-trip a small section of the spectrum is allowed to escape. The apparatus is fibre-free, offers easy wavelength range tunability, and a prototype built achieves over 10", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.09120v1.pdf"}
{"id": "1606.09290", "abstract": "  We propose a quantum circuit composed of cNOT gates and four single-qubit gates to generate a W state of three qubits. This circuit was then enhanced by integrating two-qubit gates to create a W state of four and five qubits. After a couple of enhancements, we show that an arbitrary W state can be generated depending only on the degree of enhancement. The generalized formula for the number of two-qubit gates required is given, showing that an n-qubit W-state generation can be achieved with quadratically increasing number of two-qubit gates. Also, the practical feasibility is discussed regarding photon sources and various applications of cNOT gates. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.09290v2.pdf"}
{"id": "1606.09349", "abstract": "  Zero-shot learning (ZSL) extends the conventional image classification technique to a more challenging situation where the test image categories are not seen in the training samples. Most studies on ZSL utilize side information such as attributes or word vectors to bridge the relations between the seen classes and the unseen classes. However, existing approaches on ZSL typically exploit a shared space for each type of side information independently, which cannot make full use of the complementary knowledge of different types of side information. To this end, this paper presents an MBFA-ZSL approach to embed different types of side information as well as the visual feature into one shared space. Specifically, we first develop an algorithm named Multi-Battery Factor Analysis (MBFA) to build a unified semantic space, and then employ multiple types of side information in it to achieve the ZSL. The close-form solution makes MBFA-ZSL simple to implement and efficient to run on large datasets. Extensive experiments on the popular AwA, CUB, and SUN datasets show its significant superiority over the state-of-the-art approaches. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.09349v1.pdf"}
{"id": "1607.02432", "abstract": "  We describe the redmonster automated redshift measurement and spectral classification software designed for the extended Baryon Oscillation Spectroscopic Survey (eBOSS) of the Sloan Digital Sky Survey IV (SDSS-IV). We describe the algorithms, the template standard and requirements, and the newly developed galaxy templates to be used on eBOSS spectra. We present results from testing on early data from eBOSS, where we have found a 90.5", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1607/1607.02432v2.pdf"}
{"id": "1607.03285", "abstract": "  Smoothed Dissipative Particle Dynamics (SDPD) is a mesoscopic method which allows to select the level of resolution at which a fluid is simulated. In this work, we study the consistency of the resulting thermodynamic properties as a function of the size of the mesoparticles, both at equilibrium and out of equilibrium. We also propose a reformulation of the SDPD equations in terms of energy variables. This increases the similarities with Dissipative Particle Dynamics with Energy conservation and opens the way for a coupling between the two methods. Finally, we present a numerical scheme for SDPD that ensures the conservation of the invariants of the dynamics. Numerical simulations illustrate this approach. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1607/1607.03285v2.pdf"}
{"id": "1607.04232", "abstract": "  Algorithmic randomness theory starts with a notion of an individual random object. To be reasonable, this notion should have some natural properties; in particular, an object should be random with respect to image distribution if and only if it has a random preimage. This result (for computable distributions and mappings, and Martin-Löf randomness) was known for a long time (folklore); in this paper we prove its natural generalization for layerwise computable mappings, and discuss the related quantitative results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1607/1607.04232v1.pdf"}
{"id": "1607.05969", "abstract": "  Echocardiography plays an important part in diagnostic aid in cardiac diseases. A critical step in echocardiography-aided diagnosis is to extract the standard planes since they tend to provide promising views to present different structures that are benefit to diagnosis. To this end, this paper proposes a spatial-temporal embedding framework to extract the standard view planes from 4D STIC (spatial-temporal image corre- lation) volumes. The proposed method is comprised of three stages, the frame smoothing, spatial-temporal embedding and final classification. In first stage, an L 0 smoothing filter is used to preprocess the frames that removes the noise and preserves the boundary. Then a compact repre- sentation is learned via embedding spatial and temporal features into a latent space in the supervised scheme considering both standard plane information and diagnosis result. In last stage, the learned features are fed into support vector machine to identify the standard plane. We eval- uate the proposed method on a 4D STIC volume dataset with 92 normal cases and 93 abnormal cases in three standard planes. It demonstrates that our method outperforms the baselines in both classification accuracy and computational efficiency. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1607/1607.05969v1.pdf"}
{"id": "1608.00718", "abstract": "  Secure communication protocols are becoming increasingly important, e.g. for internet-based communication. Quantum key distribution allows two parties, commonly called Alice and Bob, to generate a secret sequence of 0s and 1s called a key that is only known to themselves. Classically, Alice and Bob could never be certain that their communication was not compromised by a malicious eavesdropper. Quantum mechanics however makes secure communication possible. The fundamental principle of quantum mechanics that taking a measurement perturbs the system (unless the measurement is compatible with the quantum state) also applies to an eavesdropper. Using appropriate protocols to create the key, Alice and Bob can detect the presence of an eavesdropper by errors in their measurements. As part of the QuVis Quantum Mechanics Visualization Project, we have developed a suite of four interactive simulations that demonstrate the basic principles of three different quantum key distribution protocols. The simulations use either polarized photons or spin 1/2 particles as physical realizations. The simulations and accompanying activities are freely available for use online or download, and run on a wide range of devices including tablets and PCs. Evaluation with students over three years was used to refine the simulations and activities. Preliminary studies show that the refined simulations and activities help students learn the basic principles of QKD at both the introductory and advanced undergraduate levels. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.00718v1.pdf"}
{"id": "1608.04249", "abstract": "  Cosmic ray electrons represent a background for gamma-ray observations with Cherenkov telescopes, initiating air-showers which are difficult to distinguish from photon-initiated showers. This similarity, however, and the presence of cosmic ray electrons in every field observed, makes them potentially very useful for calibration purposes. Here we study the precision with which the relative energy scale and collection area/efficiency for photons can be established using electrons for a major next generation instrument such as CTA. We find that variations in collection efficiency on hour timescales can be corrected to better than 1", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.04249v1.pdf"}
{"id": "1608.06071", "abstract": "  A set of schemes for secure quantum communication are analyzed under the influence of non-Markovian channels. By comparing with the corresponding Markovian cases, it is seen that the average fidelity in all these schemes can be maintained for relatively longer periods of time. The effects of non-Markovian noise on a number of facets of quantum cryptography, such as quantum secure direct communication, deterministic secure quantum communication and their controlled counterparts, quantum dialogue, quantum key distribution, quantum key agreement, etc., have been extensively investigated. Specifically, a scheme for controlled quantum dialogue (CQD) is analyzed over damping, dephasing and depolarizing non-Markovian channels, and subsequently, the effect of these non-Markovian channels on the other schemes of secure quantum communication is deduced from the results obtained for CQD. The damped non-Markovian channel causes, a periodic revival in the fidelity; while fidelity is observed to be sustained under the influence of the dephasing non-Markovian channel. The depolarizing channel, as well as the other non-Markovian channels discussed here, show that the obtained average fidelity subjected to noisy environment depends on the strength of coupling between the quantum system with its surroundings and the number of rounds of quantum communication involved in a particular scheme. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.06071v1.pdf"}
{"id": "1608.06338", "abstract": "  This paper addresses the problem of continuous gesture recognition from sequences of depth maps using convolutional neutral networks (ConvNets). The proposed method first segments individual gestures from a depth sequence based on quantity of movement (QOM). For each segmented gesture, an Improved Depth Motion Map (IDMM), which converts the depth sequence into one image, is constructed and fed to a ConvNet for recognition. The IDMM effectively encodes both spatial and temporal information and allows the fine-tuning with existing ConvNet models for classification without introducing millions of parameters to learn. The proposed method is evaluated on the Large-scale Continuous Gesture Recognition of the ChaLearn Looking at People (LAP) challenge 2016. It achieved the performance of 0.2655 (Mean Jaccard Index) and ranked 3^rd place in this challenge. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.06338v2.pdf"}
{"id": "1608.07519", "abstract": "  After a brief introduction to the complex Ginzburg-Landau equation, some of its important features in two space dimensions are reviewed. A comprehensive study of the various phases observed numerically in large systems over the whole parameter space is then presented. The nature of the transitions between these phases is investigated and some theoretical problems linked to the phase diagram are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.07519v1.pdf"}
{"id": "1608.08483", "abstract": "  Programmability and verifiability lie at the heart of the software-defined networking paradigm. While OpenFlow and its match-action concept provide primitive operations to manipulate hardware configurations, over the last years, several more expressive network programming languages have been developed. This paper presents WNetKAT, the first network programming language accounting for the fact that networks are inherently weighted, and communications subject to capacity constraints (e.g., in terms of bandwidth) and costs (e.g., latency or monetary costs). WNetKAT is based on a syntactic and semantic extension of the NetKAT algebra. We demonstrate several relevant applications for WNetKAT, including cost- and capacity-aware reachability, as well as quality-of-service and fairness aspects. These applications do not only apply to classic, splittable and unsplittable (s; t)-flows, but also generalize to more complex network functions and service chains. For example, WNetKAT allows to model flows which need to traverse certain waypoint functions, which may change the traffic rate. This paper also shows the relation between the equivalence problem of WNetKAT and the equivalence problem of the weighted finite automata, which implies undecidability of the former. However, this paper also succeeds to prove the decidability of another useful problem, which is sufficient in many practical scnearios: whether an expression equals to 0. Moreover, we initiate the discussion of decidable subsets of the whole language. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.08483v4.pdf"}
{"id": "1609.01116", "abstract": "  Simultaneous broadcasting of multiple messages from the same source vertex in synchronous networks is considered under restrictions that each vertex receives at most one message in a unit time step, every received message can be sent out only in the next time step, no message is sent to already informed vertex. The number of outgoing messages in unrestricted, messages have unit length, and we assume full-duplex mode. In [9] we developed a concept of level-disjoint partitions to study simultaneous broadcasting under this model. In this work we consider the optimal number of level-disjoint partitions. We also provide a necessary condition in terms of eccentricity and girth on existence of k v-rooted level-disjoint partitions of optimal height. In particular, we provide a structural characterization of graphs admitting two level-disjoint partitions with the same root. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.01116v1.pdf"}
{"id": "1609.01151", "abstract": "  We study the properties of dipolar wave propagation in linear chains of isotropic particles with independent electric and magnetic response, embedded in vacuum. It is shown that the chain can support simultaneously right-handed modes (RHM) and left-handed modes (LHM) of transverse-polarization. The LHM are supported by the structure even if the chain's particles possess positive polarizabilities and no Bi-isotropy; the needed structural Bi-isotropy is provided by the propagator instead of by the particle's local properties. In contrast to the transverse modes in chains that consist of purely electric particles that are inherently RHM, the LHM dispersion lacks the light-line branch since their dipolar features are not aligned with the electric and magnetic fields of a right-handed plane-wave solution in free space. Furthermore, it is shown that the spatial width of the LHM is significantly smaller than that of the RHM. Excitation theory is developed, and it is shown that the chain possesses modal and excitation asymmetries that can be used to eliminate reflections from chain's termination. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.01151v3.pdf"}
{"id": "1609.02039", "abstract": "  A peculiar source in the Galactic center known as the Dusty S-cluster Object (DSO/G2) moves on a highly eccentric orbit around the supermassive black hole with the pericenter passage in the spring of 2014. Its nature has been uncertain mainly because of the lack of any information about its intrinsic geometry. For the first time, we use near-infrared polarimetric imaging data to obtain constraints about the geometrical properties of the DSO. We find out that DSO is an intrinsically polarized source, based on the significance analysis of polarization parameters, with the degree of the polarization of ∼ 30% and an alternating polarization angle as it approaches the position of Sgr A*. Since the DSO exhibits a near-infrared excess of K_ s-L'>3 and remains rather compact in emission-line maps, its main characteristics may be explained with the model of a pre-main-sequence star embedded in a non-spherical dusty envelope. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.02039v1.pdf"}
{"id": "1609.08126", "abstract": "  Positive maps applied to a subsystem of a bipartite quantum state constitute a central tool in characterising entanglement. In the multipartite case, however, the direct application of a positive but not completely positive map cannot distinguish if a state is genuinely multipartite entangled or just entangled across some bipartition. We thus generalise this bipartite concept to the multipartite setting by introducing non-positive maps that are positive on the subset of bi-separable states, but can map to a non-positive element if applied to a genuine multipartite entangled state. We explicitly construct examples of multipartite non-positive maps, obtained from positive maps via a lifting procedure, that in this fashion can reveal genuine multipartite entanglement in a robust way. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.08126v2.pdf"}
{"id": "1609.08343", "abstract": "  The space-charge-limited current in a zero thickness planar thin film depends on the geometry of the electrodes. We present a theory which is to a large extent analytical and applicable to many different lay-outs. We show that a space-charge-limited current can only be sustained if the emitting electrode induces a singularity in the field and if the singularity induced by the collecting electrode is not too strong. For those lay-outs where no space-charge-limited current can be sustained for a zero thickness film, the real thickness of the film must be taken into account using a numerical model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.08343v1.pdf"}
{"id": "1610.00786", "abstract": "  To investigate the formation of Mg-based long-period stacking ordered (LPSO) structure, we systematically study the preference of the short-range order (SRO) in metastable disordered phases of Mg-RE-Zn (RE = Y, La, Er, Ho, Dy, Tb) and Mg-Gd-Al ternary alloy systems through first-principles calculation. RE-Zn (RE = Y, Er, Ho, Dy, Tb) and Gd-Al pair clusters' probability showed the tendency of increasing. In contrast, La-Zn pair clusters' probability is not increasing, whose system dose not form LPSO structure. This preference of SRO in disordered phases of Mg-based ternary alloys certainly indicates that peculiar L12-type ordering in LPSO as well as possibility of LPSO formation should have strong correlation with SRO tendency of energetically competitive disordered phases. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.00786v2.pdf"}
{"id": "1610.02974", "abstract": "  We consider two modifications of a recently proposed three-terminal quantum dot heat engine. First, we investigate the necessity of the thermalization assumption, namely that electrons are always thermalized by inelastic processes when traveling across the cavity where the heat is supplied. Second, we analyze various arrangements of tunneling-coupled quantum dots in order to implement a transmission function that is superior to the Lorentzian transmission function of a single quantum dot. We show that the maximum power of the heat engine can be improved by about a factor of two, even for a small number of dots, by choosing an optimal structure. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.02974v2.pdf"}
{"id": "1610.03626", "abstract": "  Recent high angular resolution (∼0.2\") ALMA observations of the 1.1 mm continuum and of HCO+ J=3-2 and HCN J=3-2 gas towards the binary protostar IRS 43 reveal multiple Keplerian disks which are significantly misaligned ( 60^∘), both in inclination and position angle and also with respect to the binary orbital plane. Each stellar component has an associated circumstellar disk while the binary is surrounded by a circumbinary disk. Together with archival VLA measurements of the stellar positions over 25 years, and assuming a circular orbit, we use our continuum measurements to determine the binary separation, a = 74 ± 4 AU, and its inclination, i  30^∘. The misalignment in this system suggests that turbulence has likely played a major role in the formation of IRS 43. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.03626v2.pdf"}
{"id": "1610.03973", "abstract": "  In this paper, we investigate the band properties of 2D honeycomb plasmonic lattices consisting of metallic nanoparticles. By means of the coupled dipole method and quasi-static approximation, we theoretically analyze the band structures stemming from near-field interaction of localized surface plasmon polaritons for both the infinite lattice and ribbons. Naturally, the interaction of point dipoles decouples into independent out-of-plane and in-plane polarizations. For the out-of-plane modes, both the bulk spectrum and the range of the momentum k_∥ where edge states exist in ribbons are similar to the electronic bands in graphene. Nevertheless, the in-plane polarized modes show significant differences, which do not only possess additional non-flat edge states in ribbons, but also have different distributions of the flat edge states in reciprocal space. For in-plane polarized modes, we derived the bulk-edge correspondence, namely, the relation between the number of flat edge states at a fixed k_∥, Zak phases of the bulk bands and the winding number associated with the bulk hamiltonian, and verified it through four typical ribbon boundaries, i.e. zigzag, bearded zigzag, armchair, and bearded armchair. Our approach gives a new topological understanding of edge states in such plasmonic systems, and may also apply to other 2D \"vector wave\" systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.03973v1.pdf"}
{"id": "1610.04412", "abstract": "  In this paper we have consider the thermodynamics of a photon gas subject to the presence of a minimal measurable length following from a covariant extension of the original generalized uncertainty principle (GUP). After establishing consistently a generalized dynamics, we define a GUP deformed Maxwell invariant which serves as the basis for our study. In order to highlight the GUP effects we compute the one- and two-loop order contribution to the partition function at the high-temperature limit. Afterwards, by computing the internal energy density we conclude that the additional terms can be seen as corrections δσ_gup to the Stefan-Boltzmann law due to GUP effects. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.04412v1.pdf"}
{"id": "1610.06412", "abstract": "  We report on NuSTAR observations of the Intermediate Polar GK Persei which also behaves as a Dwarf Nova. It exhibited a Dwarf Nova outburst in 2015 March-April. The object was observed in 3-79 keV X-rays with NuSTAR, once at the outburst peak, and again in 2015 September during quiescence. The 5-50 keV flux during the outburst was 26 times higher than that during the quiescence. With a multi-temperature emission model and a reflection model, we derived the post-shock temperature as 19.2 +/- 0.7 keV in the outburst, and 38.5 +4.1/-3.6 keV in the quiescence. This temperature difference is considered to reflect changes in the radius at which the accreting matter, forming an accretion disk, is captured by the magnetosphere of the white dwarf (WD). Assuming that this radius scales as the power of -2/7 of the mass accretion rate, and utilizing the two temperature measurements, as well as the standard mass-radius relation of WDs, we determined the WD mass in GK Persei as 0.90 +/- 0.06 solar masses. The magnetic field is estimated as 4*10^5 G. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.06412v1.pdf"}
{"id": "1610.07357", "abstract": "  Dense, He-rich atmospheres of cool white dwarfs represent a challenge to the modeling. This is because these atmospheres are constituted of a dense fluid in which strong multi-atomic interactions determine their physics and chemistry. Therefore, the ideal-gas-based description of absorption is no longer adequate, which makes the opacities of these atmospheres difficult to model. This is illustrated with severe problems in fitting the spectra of cool, He-rich stars. Good description of the infrared (IR) opacity is essential for proper assignment of the atmospheric parameters of these stars. Using methods of computational quantum chemistry we simulate the IR absorption of dense He/H media. We found a significant IR absorption from He atoms (He-He-He CIA opacity) and a strong pressure distortion of the H_2-He collision-induced absorption (CIA). We discuss the implication of these results for interpretation of the spectra of cool stars. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.07357v1.pdf"}
{"id": "1611.01936", "abstract": "  The graph isomorphism problem is a main problem which has numerous applications in different fields. Thus, finding an efficient and easy to implement method to discriminate non-isomorphic graphs is valuable. In this paper, a new method is introduced which is very simple and easy to implement, but very efficient in discriminating non-isomorphic graphs, in practice. This method does not need any heuristic attempt and based on the eigenvalues of a new matrix representation for graphs. It, almost always, separates non-isomorphic n-vertex graphs in time O(n^3) and in worst cases such as strongly regular graphs, in time O(n^4). Here, we show that this method, successfully, characterizes the isomorphism classes of studied instances of strongly regular graphs (up to 64 vertices). Strongly regular graphs are believed to be hard cases of the graph isomorphism problem. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.01936v1.pdf"}
{"id": "1611.02324", "abstract": "  Recently a new class of asymptotically AdS ultra-spinning black holes has been constructed with a noncompact horizon of finite area [1], in which the asymptotic rotation is effectively boosted to the speed of light. We employ this technique for four-dimensional U(1)^4 and five-dimensional U(1)^3 gauged supergravity black holes. The obtained new exact black hole solutions for both cases possess a noncompact horizon; their topologies are a sphere with two punctures. We then demonstrate that the ultra-spinning limit commutes with the extremality condition as well as the near horizon limit for both black holes. We also show that the near horizon extremal geometries of the resulting ultra-spinning gauged supergravity black holes lead to the well-known result which contains an AdS_2 throat. We then obtain the [(d-1)/2] central charges of the dual CFTs. By assuming the Cardy formula, we show that despite the noncompactness of the horizon, microscopic entropy of the dual CFT is precisely equivalent to the Bekenstein-Hawking entropy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.02324v2.pdf"}
{"id": "1611.03359", "abstract": "  There are excellent opportunities to produce excited heavy hyper residues in relativistic hadron and peripheral heavy-ion collisions. We investigate the disintegration of such residues into hyper nuclei via evaporation of baryons and light clusters and their fission. Previously these processes were well known for normal nuclei as the decay channels at low excitation energies. We have generalized these models for the case of hyper-matter. In this way we make extension of nuclear reaction studies at low temperature into the strange sector. We demonstrate how the new decay channels can be integrated in the whole disintegration process. Their importance for mass and isotope distributions of produced hyper-fragments is emphasized. New and exotic isotopes obtained within these processes may provide a unique opportunity for investigating hyperon interaction in nuclear matter. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.03359v1.pdf"}
{"id": "1611.04296", "abstract": "  The spin-1/2 Ising octahedron and dodecahedron with a unique antiferromagnetic interaction display an outstanding magnetization jump at zero magnetic field, which consequently leads to a giant magnetocaloric effect during the adiabatic demagnetization. In the present work we report temperature dependences of two basic magnetocaloric response functions: the isothermal entropy change and the adiabatic change of temperature. It is shown that the Ising octahedron and dodecahedron generally exhibit a large negative isothermal entropy change upon increasing of the magnetic field, which serves in evidence of their cooling performance. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.04296v1.pdf"}
{"id": "1611.04310", "abstract": "  We propose a laboratory experience aimed at undergraduate physics students to understand the main features of the photoelectric effect and to perform a measurement of the ratio h/e, where h is the Planck's constant and e is the electron charge. The experience is based on the method developed by Millikan for his measurements on the photoelectric effect in the years from 1912 to 1915. The experimental setup consists of a photomultiplier tube (PMT) equipped with a voltage divider properly modified to set variable retarding potentials between the photocathode and the first dynode, and a set of LEDs emitting at different wavelengths. The photocathode is illuminated with the various LEDs and, for each wavelength of the incident light, the output anode current is measured as a function of the retarding potential applied between the cathode and the first dynode. From each measurement, a value of the stopping potential for the anode current is derived. Finally, the stopping potentials are plotted as a function of the frequency of the incident light, and a linear fit is performed. The slope and the intercept of the line allow respectively to evaluate the ratio h/e and the ratio W/e, where W is the work function of the photocathode. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.04310v1.pdf"}
{"id": "1611.04550", "abstract": "  We use a Metropolis algorithm to calculate the finite temperature spectral weight of three related models that have identical quasiparticles at T=0, if the exchange favors the appearance of a ferromagnetic background. The low-energy behavior of two of the models remains equivalent at finite temperature, however that of the third does not because its low-energy behavior is controlled by rare events due to thermal fluctuations, which transfer spectral weight well below the T=0 quasiparticle peaks and generate a pseudogap-like phenomenology. Our results demonstrate that having T=0 spectra with similar quasiparticles is not a sufficient condition to ensure that two models are equivalent, i.e. that their low-energy properties are similar. We also argue that the pseudogap-like phenomenology is quite generic for models of t-J type, appearing in any dimension and for carriers injected into both ferromagnetic and antiferromagnetic backgrounds. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.04550v1.pdf"}
{"id": "1611.08766", "abstract": "  Gel-immobilized colloidal crystals were prepared to obtain hybrid plasmonic-photonic crystals, in which electric field enhancement to a greater extent than that due to localized surface plasmons (LSP) alone was expected due to coupling between LSP and the photonic band. Polystyrene colloidal crystals immobilized by the N-(hydroxymethyl)acrylamide gel were immersed in an aqueous dispersion of gold nanoparticles (AuNPs). Then, the gel-immobilized colloidal crystals were picked out and immersed in an ionic liquid mixture. The surfaces of the gel-immobilized colloidal crystals immersed in the AuNP dispersion were observed via scanning electron microscopy after this solvent substitution. The lattice spacing of the colloidal crystal varied as the composition of the ionic liquid mixture was changed. The composition was determined so that the photonic band gap wavelength coincided with the LSP wavelength. Further, the reflection spectra were measured. Thus, we successfully prepared a hybrid plasmonic-photonic crystal. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.08766v1.pdf"}
{"id": "1611.10187", "abstract": "  Assessing and predicting the complex concept of software quality is still challenging in practice as well as research. Activity-based quality models break down this complex con- cept into more concrete definitions, more precisely facts about the system, process and environment and their impact on ac- tivities performed on and with the system. However, these models lack an operationalisation that allows to use them in assessment and prediction of quality. Bayesian Networks (BN) have been shown to be a viable means for assessment and prediction incorporating variables with uncertainty. This paper describes how activity-based quality models can be used to derive BN models for quality assessment and pre- diction. The proposed approach is demonstrated in a proof of concept using publicly available data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.10187v1.pdf"}
{"id": "1612.01268", "abstract": "  Systems with coupled cavities and waveguides have been demonstrated as optical switches and optical sensors. To optimize the functionalities of these optical devices, Fano resonance with asymmetric and steep spectral line shape has been used. We theoretically propose a coupled photonic crystal cavity-waveguide structure to achieve Fano resonance by placing partially reflecting elements in waveguide. To enhance Fano resonance, optical gain material is introduced into the cavity. As the gain increases, the transmission line shape becomes steepened and the transmissivity can be six times enhanced, giving a large contrast by a small frequency shift. It is prospected that the gain enhanced Fano resonance is very useful for optical switches and optical sensors. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.01268v1.pdf"}
{"id": "1612.03379", "abstract": "  We study some statistical properties for the behavior of the average squared velocity – hence the temperature – for an ensemble of classical particles moving in a billiard whose boundary is time dependent. We assume the collisions of the particles with the boundary of the billiard are inelastic leading the average squared velocity to reach a steady state dynamics for large enough time. The description of the stationary state is made by using two different approaches: (i) heat transfer motivated by the Fourier law and, (ii) billiard dynamics using either numerical simulations and theoretical description. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.03379v1.pdf"}
{"id": "1612.06282", "abstract": "  In a recent paper, Erik Verlinde has developed the interesting possibility that spacetime and gravity may emerge from the entangled structure of an underlying microscopic theory. In this picture, dark matter arises as a response to the standard model of particle physics from the delocalized degrees of freedom that build up the dark energy component of the Universe. Dark matter physics is then regulated by a characteristic acceleration scale a_0, identified with the radius of the (quasi)-de Sitter universe we inhabit. For a point particle matter source, or outside an extended spherically symmetric object, MOND's empirical fitting formula is recovered. However, Verlinde's theory critically departs from MOND when considering the inner structure of galaxies, differing by a factor of 2 at the centre of a regular massive body. For illustration, we use the eight classical dwarf spheroidal satellites of the Milky Way. These objects are perfect testbeds for the model given their approximate spherical symmetry, measured kinematics, and identified missing mass. We show that, without the assumption of a maximal deformation, Verlinde's theory can fit the velocity dispersion profile in dwarf spheroidals with no further need of an extra dark particle component. If a maximal deformation is considered, the theory leads to mass-to-light ratios that are marginally larger than expected from stellar population and formation history studies. We also compare our results with the recent phenomenological interpolating MOND function of McGaugh et al, and find a departure that, for these galaxies, is consistent with the scatter in current observations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.06282v2.pdf"}
{"id": "1612.06435", "abstract": "  This work presents a novel descriptor for texture images based on fractal geometry and its application to image analysis. The descriptors are provided by estimating the triangular prism fractal dimension under different scales with a weight exponential parameter, followed by dimensionality reduction using Karhunen-Loève transform. The efficiency of the proposed descriptors is tested on two well-known texture data sets, that is, Brodatz and Vistex, both for classification and image retrieval. The novel method is also tested concerning invariances in situations when the textures are rotated or affected by Gaussian noise. The obtained results outperform other classical and state-of-the-art descriptors in the literature and demonstrate the power of the triangular descriptors in these tasks, suggesting their use in practical applications of image analysis based on texture features. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.06435v1.pdf"}
{"id": "1612.08218", "abstract": "  Electronic properties of III-V semiconductor alloys are examined using first principles with the focus on the spatial localization of electronic states. We compare localization at the band edges due to various isovalent impurities in a host GaAs including its impact on the photoluminescence line widths and carrier mobilities. The extremity of localization at the band edges is correlated with the ability of individual elements to change the band gap and the relative band alignment. Additionally, the formation energies of substitutional defects are calculated and linked to challenges associated with the growth and formability of alloys. A spectrally-resolved inverse participation ratio is used to map localization in prospective GaAs-based materials alloyed with B, N, In, Sb, and Bi for 1.55 μm wavelength telecommunication lasers. This analysis is complemented by a band unfolding of the electronic structure and discussion of implications of localization on the optical gain and Auger losses. Correspondence with experimental data on broadening of the photoluminescence spectrum and charge carrier mobilities show that the localization characteristics can serve as a guideline for engineering of semiconductor alloys. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.08218v3.pdf"}
{"id": "1612.08292", "abstract": "  In this article, after introducing a kind of q-deformation in quantum mechanics, first, q-deformed form of Dirac equation in relativistic quantum mechanics is derived. Then three important scat erring problem in physics are studied. All results have satisfied what we had expected before. Furthermore, effects of all parameters in the problems on the reflection and transmission coefficients are calculated and shown graphically. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.08292v1.pdf"}
{"id": "1612.08540", "abstract": "  Turbulence intensity profiles are compared for smooth- and rough-wall pipe flow measurements made in the Princeton Superpipe. The profile development in the transition from hydraulically smooth to fully rough flow displays a propagating sequence from the pipe wall towards the pipe axis. The scaling of turbulence intensity with Reynolds number shows that the smooth- and rough wall level deviates with increasing Reynolds number. We quantify the correspondence between turbulence intensity and the friction factor. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.08540v7.pdf"}
{"id": "1701.00104", "abstract": "  A partial password is a mode of password-based authentication that is widely used, especially in the financial sector. It is based on a challenge-response protocol, where at each login attempt, a challenge requesting characters from randomly selected positions of a pre-shared secret is presented to the user. This model could be seen as a cheap way of preventing for example a malware or a key-logger installed on a user's device to learn the full password in a single step. Despite of the widespread adoption of this mechanism, especially by many UK banks, there is limited material in the open literature. Questions like how the security of the scheme varies with the sampling method employed to form the challenges or what are the existing server-side implementations are left unaddressed. In this paper, we study questions like how the security of this mechanism varies in relation to the number of challenge-response pairs available to an attacker under different ways of generating challenges. In addition, we discuss possible server-side implementations as \"unofficially\" listed in different online forums by information security ex- perts. To the best of our knowledge there is no formal academic literature in this direction and one of the aims of this paper is to motivate other researchers to study this topic. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.00104v1.pdf"}
{"id": "1701.00251", "abstract": "  We consider the problem of learning from noisy data in practical settings where the size of data is too large to store on a single machine. More challenging, the data coming from the wild may contain malicious outliers. To address the scalability and robustness issues, we present an online robust learning (ORL) approach. ORL is simple to implement and has provable robustness guarantee – in stark contrast to existing online learning approaches that are generally fragile to outliers. We specialize the ORL approach for two concrete cases: online robust principal component analysis and online linear regression. We demonstrate the efficiency and robustness advantages of ORL through comprehensive simulations and predicting image tags on a large-scale data set. We also discuss extension of the ORL to distributed learning and provide experimental evaluations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.00251v1.pdf"}
{"id": "1701.01172", "abstract": "  Multi-frequency, multi-epoch ATCA observations of a sample of AGN resulted in the identification of 9 new candidate Giga-hertz Peaked Spectrum (GPS) sources. Here we present Long Baseline Array observations at 4.8 GHz of the four candidates with no previously published VLBI image, and consider these together with previously published VLBI images of the other five sources. We find core-jet or compact double morphologies dominate, with further observations required to distinguish between these two possibilities for some sources. One of the nine candidates, PKS 1831-711, displays appreciable variability, suggesting its GPS spectrum is more ephemeral in nature. We focus in particular on the apparent relationship between a narrow spectral width and \"compact double\" parsec-scale morphology, finding further examples, but also exceptions to this trend. An examination of the VLBI morphologies high-redshift (z>3) sub-class of GPS sources suggests that core-jet morphologies predominate in this class. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.01172v1.pdf"}
{"id": "1701.02103", "abstract": "  The distribution of waiting times between successive tunneling events is an already established method to characterize current fluctuations in mesoscopic systems. Here, I investigate mechanisms generating correlations between subsequent waiting times in two model systems, a pair of capacitively coupled quantum dots and a single-level dot attached to spin-polarized leads. Waiting time correlations are shown to give an insight into the internal dynamics of the system, for example they allow distinction between different mechanisms of the noise enhancement. Moreover, the presence of correlations breaks the validity of the renewal theory. This increases the number of independent cumulants of current fluctuation statistics, thus providing additional sources of information about the transport mechanism. I also propose a method for inferring the presence of waiting time correlations based on low-order current correlation functions. This method gives a way to extend the analysis of nonrenewal current fluctuations to the systems for which single-electron counting is not experimentally feasible. The experimental relevance of the findings is also discussed, for example reanalysis of previous results concerning transport in quantum dots is suggested. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.02103v1.pdf"}
{"id": "1701.03687", "abstract": "  A recently proposed technique correlating electric fields and particle velocity distributions is applied to single-point time series extracted from linearly unstable, electrostatic numerical simulations. The form of the correlation, which measures the transfer of phase-space energy density between the electric field and plasma distributions and had previously been applied to damped electrostatic systems, is modified to include the effects of drifting equilibrium distributions of the type that drive counter-streaming and bump-on-tail instabilities. By using single-point time series, the correlation is ideal for diagnosing dynamics in systems where access to integrated quantities, such as energy, is observationally infeasible. The velocity-space structure of the field-particle correlation is shown to characterize the underlying physical mechanisms driving unstable systems. The use of this correlation in simple systems will assist in its eventual application to turbulent, magnetized plasmas, with the ultimate goal of characterizing the nature of mechanisms that damp turbulent fluctuations in the solar wind. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.03687v1.pdf"}
{"id": "1701.05482", "abstract": "  The similarity of the host galaxy of FRB 121102 with those of long gamma-ray bursts and Type I super-luminous supernovae suggests that this FRB could be associated with a young magnetar. By assuming the FRB emission to be produced within the magnetosphere, we derive a lower limit on the age of the magnetar, after which GHz emission is able to escape freely from the dense relativistic wind of the magnetar. Another lower limit is obtained by requiring the dispersion measure contributed by the electron/positron pair wind to be consistent with the observations of the host galaxy. Furthermore, we also derive some upper limits on the magnetar age with discussions on possible energy sources of the FRB emission and the recently-discovered persistent radio counterpart. As a result, some constraints on model parameters are addressed by reconciling the lower limits with the possible upper limits that are derived with an assumption of rotational energy source. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.05482v3.pdf"}
{"id": "1701.05975", "abstract": "  Recent decades have witnessed the tremendous development of network science, which indeed brings a new and insightful language to model real systems of different domains. Betweenness, a widely employed centrality in network science, is a decent proxy in investigating network loads and rankings. However, the extremely high computational cost greatly prevents its applying on large networks. Though several parallel algorithms have been presented to reduce its calculation cost on unweighted networks, a fast solution for weighted networks, which are in fact more ubiquitous than unweighted ones in reality, is still missing. In this study, we develop an efficient parallel GPU-based approach to boost the calculation of betweenness centrality on very large and weighted networks. Comprehensive and systematic evaluations on both synthetic and real-world networks demonstrate that our solution can arrive the performance of 30x to 150x speedup over the CPU implementation by integrating the work-efficient and warp-centric strategies. Our algorithm is completely open-sourced and free to the community and it is public available through https://dx.doi.org/10.6084/m9.figshare.4542405. Considering the pervasive deployment and declining price of GPU on personal computers and servers, our solution will indeed offer unprecedented opportunities for exploring the betweenness related problems in network science. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.05975v1.pdf"}
{"id": "1701.06678", "abstract": "  The reliability function of memoryless channels with noiseless feedback and variable-length coding has been found to be a linear function of the average rate in the classic work of Burnashev. In this work we consider unifilar channels with noiseless feedback and study upper bounds for the channel reliability function with variable length codes. In unifilar channels the channel state is known to the transmitter but is unknown to the receiver. We generalize Burnashev's analysis and derive a similar expression which is linear in average rate and depends on the channel capacity, as well as an additional parameter which relates to a sequential binary hypothesis testing problem over this channel. This parameter is evaluated by setting up an appropriate Markov decision process (MDP). Furthermore, an upper bound for this parameter is derived using a simplified MDP. Numerical evaluation of the parameter for several binary input/state/output unifilar channels hints at the optimal transmission strategies. Such strategies are studied in a companion paper to provide lower (achievable) bounds on the channel reliability function. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.06678v4.pdf"}
{"id": "1701.07891", "abstract": "  This paper aims to maximize optical force and torque on arbitrary micro- and nano-scale objects using numerically optimized structured illumination. By developing a numerical framework for computer-automated design of 3d vector-field illumination, we demonstrate a 20-fold enhancement in optical torque per intensity over circularly polarized plane wave on a model plasmonic particle. The nonconvex optimization is efficiently performed by combining a compact cylindrical Bessel basis representation with a fast boundary element method and a standard derivative-free, local optimization algorithm. We analyze the optimization results for 2000 random initial configurations, discuss the tradeoff between robustness and enhancement, and compare the different effects of multipolar plasmon resonances on enhancing force and torque. All results are obtained using open-source computational software available online. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.07891v1.pdf"}
{"id": "1702.00318", "abstract": "  The longest arc-preserving common subsequence problem is an NP-hard combinatorial optimization problem from the field of computational biology. This problem finds applications, in particular, in the comparison of arc-annotated Ribonucleic acid (RNA) sequences. In this work we propose a simple, hybrid evolutionary algorithm to tackle this problem. The most important feature of this algorithm concerns a crossover operator based on solution merging. In solution merging, two or more solutions to the problem are merged, and an exact technique is used to find the best solution within this union. It is experimentally shown that the proposed algorithm outperforms a heuristic from the literature. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.00318v1.pdf"}
{"id": "1702.00420", "abstract": "  We study the consistency of large-field inflation in low-energy effective field theories of string theory. In particular, we focus on the stability of Kähler moduli in the particularly interesting case where the non-perturbative superpotential of the Kähler sector explicitly depends on the inflaton field. This situation arises generically due to one-loop corrections to the instanton action. The field dependence of the modulus potential feeds back into the inflationary dynamics, potentially impairing slow roll. We distinguish between world-sheet instantons from Euclidean D-branes, which typically yield polynomial one-loop Pfaffians, and gaugino condensates, which can yield exponential or periodic corrections. In all scenarios successful slow-roll inflation imposes bounds on the magnitude of the one-loop correction, corresponding to constraints on possible compactifications. While we put a certain emphasis on Type IIB constructions with mobile D7-branes, our results seem to apply more generally. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.00420v2.pdf"}
{"id": "1702.00494", "abstract": "  Rydberg atom-based electrometry enables traceable electric field measurements with high sensitivity over a large frequency range, from gigahertz to terahertz. Such measurements are particularly useful for the calibration of radio frequency and terahertz devices, as well as other applications like near field imaging of electric fields. We utilize frequency modulated spectroscopy with active control of residual amplitude modulation to improve the signal to noise ratio of the optical readout of Rydberg atom-based radio frequency electrometry. Matched filtering of the signal is also implemented. Although we have reached similarly, high sensitivity with other read-out methods, frequency modulated spectroscopy is advantageous because it is well-suited for building a compact, portable sensor. In the current experiment, ∼ 3 μ V cm^-1Hz^-1/2 sensitivity is achieved and is found to be photon shot noise limited. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.00494v1.pdf"}
{"id": "1702.01334", "abstract": "  Iris is one of the popular biometrics that is widely used for identity authentication. Different features have been used to perform iris recognition in the past. Most of them are based on hand-crafted features designed by biometrics experts. Due to tremendous success of deep learning in computer vision problems, there has been a lot of interest in applying features learned by convolutional neural networks on general image recognition to other tasks such as segmentation, face recognition, and object detection. In this paper, we have investigated the application of deep features extracted from VGG-Net for iris recognition. The proposed scheme has been tested on two well-known iris databases, and has shown promising results with the best accuracy rate of 99.4%, which outperforms the previous best result. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.01334v1.pdf"}
{"id": "1702.01659", "abstract": "  Cryogenic 22-pole ion traps have found many applications in ion-molecule reaction kinetics and in high resolution molecular spectroscopy. For most of these applications it is important to know the translational and internal temperatures of the trapped ions. Here, we present detailed rotational state thermometry measurements over an extended temperature range for the two ion/buffer gas systems OH-/He and OD-/HD with ion-to-neutral mass ratios of 4.25 and 6 respectively. The measured rotational temperatures show a termination of the thermalisation with the buffer gas around 25K, independent of mass ratio and confinement potential of the trap. Different possible explanations for this incomplete thermalisation have been investigated, among them the thermalisation of the buffer gas and the heating due to room temperature blackbody radiation and room temperature gas entering the trap. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.01659v1.pdf"}
{"id": "1702.01680", "abstract": "  The Born rule provides a probability vector (distribution) with a quantum state for a measurement setting. For two settings, we have a pair of vectors from the same quantum state. Each pair forms a combined-probability vector that obeys certain quantum constraints, which are triangle inequalities in our case. Such a restricted set of combined vectors, titled combined-probability space, is presented here for a d-level quantum system (qudit). The combined space turns out a compact convex subset of a Euclidean space, and all its extreme points come from a family of parametric curves. Considering a suitable concave function on the combined space to estimate the uncertainty, we deliver an uncertainty relation by finding its global minimum at the curves for a qudit. If one chooses an appropriate concave (or convex) function, then there is no need to search for the absolute minimum (maximum) on the whole space, it will be at the parametric curves. So these curves are quite useful for establishing an uncertainty (or a certainty) relation for a general pair of settings. In the paper, we also demonstrate that many known tight (un)certainty relations for a qubit can be obtained with the triangle inequalities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.01680v2.pdf"}
{"id": "1702.01794", "abstract": "  In this paper, we propose a new robustness notion that is applicable for certifying systems' safety with respect to external disturbance signals. The proposed input-to-state safety (ISSf) notion allows us to certify systems' safety in the presence of the disturbances which is analogous to the notion of input-to-state stability (ISS) for analyzing systems' stability. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.01794v1.pdf"}
{"id": "1702.02795", "abstract": "  The validity of General Relativity, after 100 years, is supported by solid experimental evidence. However, there is a lot of interest in pushing the limits of precision by other experiments. Here we focus our attention on the equivalence principle, in particular the strong form. The results of ground experiments and lunar laser ranging have provided the best upper limit on the Nordtvedt parameter η that models deviations from the strong equivalence principle. Its uncertainty is currently σ[η] =4.4 × 10^-4. In the first part of this paper we will describe the experiment, to measure η, that will be done by the future mission BepiColombo. The expected precision on η is ≈ 10^-5. In the second part we will consider the ranging between the Earth and a spacecraft orbiting near the Sun-Earth Lagrangian points to get an independent measurement of η. In this case, we forecast a constraint similar to that achieved by lunar laser ranging. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.02795v1.pdf"}
{"id": "1702.03697", "abstract": "  The resonant process of electron-positron pairproduction by an electron in a subcritical magnetic field has been studied when the pair is produced to exited Landau levels. The spin dependency of the process rate has been analyzed. In the spin state with the greatest rate the virtual photon is emitted with a flip of electron spin. This behavior is not suppressed for radiative transitions from a relativistic initial state to low energy levels. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.03697v1.pdf"}
{"id": "1702.03942", "abstract": "  We report the discovery of the quadruply lensed quasar J1433+6007, mined in the SDSS DR12 photometric catalogues using a novel outlier-selection technique, without prior spectroscopic or UV excess information. Discovery data obtained at the Nordic Optical telescope (NOT, La Palma) show nearly identical quasar spectra at z_s=2.74 and four quasar images in a fold configuration, one of which sits on a blue arc. The deflector redshift is z_l=0.407, from Keck-ESI spectra. We describe the selection procedure, discovery and follow-up, image positions and BVRi magnitudes, and first results and forecasts from simple lens models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.03942v1.pdf"}
{"id": "1702.04319", "abstract": "  We propose to use intensity correlation microscopy in combination with structured illumination to image quantum emitters that exhibit antibunching with a spatial resolution reaching far beyond the Rayleigh limit. Combining intensity measurements and intensity auto correlations up to order m creates an effective PSF with FWHM shrunk by the factor √(m). Structured Illumination microscopy on the other hand introduces a resolution improvement of factor 2 by use of the principle of moiré fringes. Here, we show that for linear low-intensity excitation and linear optical detection the simultaneous use of both techniques leads to an in theory unlimited resolution power with the improvement scaling favorably as m + √(m) in dependence of the correlation order m. Hence, yielding this technique to be of interest in microscopy for imaging a variety of samples including biological ones. We present the underlying theory and simulations demonstrating the highly increased spatial superresolution, and point out requirements for an experimental implementation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.04319v1.pdf"}
{"id": "1702.04469", "abstract": "  We show that the conditional shape invariance symmetry can be used as a very powerful tool to calculate the eigenvalues of the mixed potential V (r) = ar + br^2 +c/r + l(l+1)/r^2 for a restricted set of potential parameters. The energy for any state can be obtained algebraically, albeit for a severely restricted set of potential parameters. We also indicate that each member of the hierarchy of Hamiltonians is basically conditionally translational shape invariant. Comparison of analytically obtained results with numerical results is also presented. Our present methodology can be taken as an alternative treatment for the calculation of any higher order excited states of conditionally exactly solvable (CES) potentials. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.04469v1.pdf"}
{"id": "1702.05420", "abstract": "  In this paper, we present experimental studies on a cooperative control system for human-robotic networks with inter-robot communication delays. We first design a cooperative controller to be implemented on each robot so that their motion are synchronized to a reference motion desired by a human operator, and then point out that each robot motion ensures passivity. Inter-robot communication channels are then designed via so-called scattering transformation which is a technique to passify the delayed channel. The resulting robotic network is then connected with human operator based on passivity theory. In order to demonstrate the present control architecture, we build an experimental testbed consisting of multiple robots and a tablet. In particular, we analyze the effects of the communication delays on the human operator's behavior. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.05420v2.pdf"}
{"id": "1702.05578", "abstract": "  Branching bisimilarity on normed Basic Process Algebra (BPA) was claimed to be EXPTIME-hard in previous papers without any explicit proof. Recently it is reminded by Jančar that the claim is not so dependable. In this paper, we develop a new complete proof for EXPTIME-hardness of branching bisimilarity on normed BPA. We also prove the associate regularity problem on normed BPA is PSPACE-hard and in EXPTIME. This improves previous P-hard and NEXPTIME result. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.05578v1.pdf"}
{"id": "1702.07122", "abstract": "  We study the effect of system reservoir coupling on currents flowing through quantum junctions. We consider two simple double-quantum dot configurations coupled to two external fermionic reservoirs and study the net current flowing between the two reservoirs. The net current is partitioned into currents carried by the eigenstates of the system and by the coherences between the eigenstates induced due to coupling with the reservoirs. We find that current carried by populations is always positive whereas current carried by coherences are negative for large couplings. This results in a non-monotonic dependence of the net current on the coupling strength. We find that in certain cases, the net current can vanish at large couplings due to cancellation between currents carried by the eigenstates and by the coherences. These results provide new insights into the non-trivial role of system-reservoir couplings on electron transport through quantum dot junctions. In the presence of weak coulomb interactions, net current as a function of system reservoir coupling strength shows similar trends as for the non-interacting case. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.07122v2.pdf"}
{"id": "1702.07846", "abstract": "  We consider the remote creation of a mixed state in a one-qubit receiver connected to two two-qubit senders via different channels. Channels are assumed to be chains of spins (qubits) with nearest-neighbor interactions, no external fields are being applied. The problem of sharing the creatable region of the receiver's state-space between two senders is considered for a communication line with the receiver located asymmetrically with respect to these senders (asymmetric communication line). An example of a quantum register realizing simple functions is constructed on the basis of a symmetric communication line. In that setup, the initial states of the two senders serve as input and control signals, respectively, while the state of the receiver at a proper time instant is considered as the output signal. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.07846v3.pdf"}
{"id": "1702.08024", "abstract": "  Results of the search for ∼ (10^16 - 10^17.5) eV primary cosmic-ray photons with the data of the Moscow State University (MSU) Extensive Air Shower (EAS) array are reported. The full-scale reanalysis of the data with modern simulations of the installation does not confirm previous indications of the excess of gamma-ray candidate events. Upper limits on the corresponding gamma-ray flux are presented. The limits are the most stringent published ones at energies ∼ 10^17 eV. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.08024v1.pdf"}
{"id": "1703.00919", "abstract": "  The paper presents a novel approach to occlusion handling problem in depth estimation using three views. A solution based on modification of similarity cost function is proposed. During the depth estimation via optimization algorithms like Graph Cut similarity metric is constantly updated so that only non-occluded fragments in side views are considered. At each iteration of the algorithm non-occluded fragments are detected based on side view virtual depth maps synthesized from the best currently estimated depth map of the center view. Then similarity metric is updated for correspondence search only in non-occluded regions of the side views. The experimental results, conducted on well-known 3D video test sequences, have proved that the depth maps estimated with the proposed approach provide about 1.25 dB virtual view quality improvement in comparison to the virtual view synthesized based on depth maps generated by the state-of-the-art MPEG Depth Estimation Reference Software. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.00919v2.pdf"}
{"id": "1703.01724", "abstract": "  A new class of solution describing an anisotropic stellar configuration satisfying Karmarkar's condition i.e. spherically symmetric metric of embedding class 1, is reported. It has been shown that the compact star model is physically well-behaved and meet all the physical requirements for a stable configuration in hydrostatic equilibrium. Our model describes compact stars like Vela X-1 and 4U1608-52 to a very good approximation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.01724v2.pdf"}
{"id": "1703.03291", "abstract": "  Quantum games with incomplete information can be studied within a Bayesian framework. We consider a version of prisoner's dilemma (PD) in this framework with three players and characterize the Nash equilibria. A variation of the standard PD game is set up with two types of the second prisoner and the first prisoner plays with them with probability p and 1-p respectively. The Bayesian nature of the game manifests in the uncertainty that the first prisoner faces about his opponent's type which is encoded either in a classical probability or in the amplitudes of a wave function. Here, we consider scenarios with asymmetric payoffs between the first and second prisoner for different values of the probability, p, and the entanglement. Our results indicate a class of Nash equilibria (NE) with rich structures, characterized by a phase relationship on the strategies of the players. The rich structure that can be exploited by the referee to set up rules of the game to push the players towards a specific class of NE. These results provide a deeper insight into the quantum advantages of Bayesian games over their classical counterpart. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.03291v1.pdf"}
{"id": "1703.04509", "abstract": "  Star formation from the interstellar medium of galactic disks is a basic process controlling the evolution of galaxies. Understanding the star formation rate in a local patch of a disk with a given gas mass is thus an important challenge for theoretical models. Here we simulate a kiloparsec region of a disk, following the evolution of self-gravitating molecular clouds down to subparsec scales, as they form stars that then inject feedback energy by dissociating and ionizing UV photons and supernova explosions. We assess the relative importance of each feedback mechanism. We find that H_2-dissociating feedback results in the largest absolute reduction in star formation compared to the run with no feedback. Subsequently adding photoionization feedback produces a more modest reduction. Our fiducial models that combine all three feedback mechanisms yield, without fine-tuning, star formation rates that are in excellent agreement with observations, with H_2-dissociating photons playing a crucial role. Models that only include supernova feedback—a common method in galaxy evolution simulations—settle to similar star formation rates, but with very different temperature and chemical states of the gas, and with very different spatial distributions of young stars. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.04509v2.pdf"}
{"id": "1703.07369", "abstract": "  A geometric entropy is defined as the Riemannian volume of the parameter space of a statistical manifold associated with a given network. As such it can be a good candidate for measuring networks complexity. Here we investigate its ability to single out topological features of networks proceeding in a bottom-up manner: first we consider small size networks by analytical methods and then large size networks by numerical techniques. Two different classes of networks, the random graphs and the scale–free networks, are investigated computing their Betti numbers and then showing the capability of geometric entropy of detecting homologies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.07369v1.pdf"}
{"id": "1703.07636", "abstract": "  This paper study the evolution of the universe filled with a neutral mass dimension one fermionic field, sometimes called Elko. The numerical analysis of the coupled system of equations furnish a scale factor growth and energy density evolution that correctly reproduces the inflationary phase of the universe. After that, supposing a mechanism of energy transference to ordinary matter, the initial conditions generated after inflation drives the radiation dominated phase and also the subsequent dark matter evolution, since the Elko field is a good dark matter candidate. The energy density of the field at the end of inflation, at the end of radiation phase and for present time are in agreement to the standard model estimates. The analysis was performed with a potential containing a quadratic mass term plus a quartic self-interaction term, which follows naturally from the theory of mass dimension one fermions. It is interesting to notice that inflation occurs when the field makes a kind of transition around the Planck mass scale. The number of e-foldings during inflation was found to be strongly dependent on the initial conditions of the Elko field, as occurs in chaotic inflationary models. An upper mass limit for Elko field has been obtained as m<10^9GeV. A possible interpretation of both inflationary phase and recent cosmic acceleration as a consequence of a kind of Pauli exclusion principle is presented at the end. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.07636v2.pdf"}
{"id": "1703.07746", "abstract": "  This paper is devoted to an investigation of Euclidean wormholes made by fuzzy instantons. We investigate the Euclidean path integral in anti-de Sitter space. In Einstein gravity, we introduce a scalar field with a potential. Because of the analyticity, there is a contribution of complex-valued instantons, so-called fuzzy instantons. If we have a massless scalar field, then we obtain Euclidean wormholes, where the probabilities become smaller and smaller as the size of the throat becomes larger and larger. If we introduce a non-trivial potential, then in order to obtain a non-zero tunneling rate, we need to tune the shape of the potential. With the O(4) symmetry, after the analytic continuation to the Lorentzian time, the wormhole throat should expand to infinity. However, by adding mass, one may obtain an instant wormhole that should eventually collapse to the event horizon. The existence of Euclidean wormholes is related to the stability or unitarity issues of anti-de Sitter space. We are not conclusive yet, but we carefully comment on these physical problems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.07746v3.pdf"}
{"id": "1703.08071", "abstract": "  It is widely recognized that citation counts for papers from different fields cannot be directly compared because different scientific fields adopt different citation practices. Citation counts are also strongly biased by paper age since older papers had more time to attract citations. Various procedures aim at suppressing these biases and give rise to new normalized indicators, such as the relative citation count. We use a large citation dataset from Microsoft Academic Graph and a new statistical framework based on the Mahalanobis distance to show that the rankings by well known indicators, including the relative citation count and Google's PageRank score, are significantly biased by paper field and age. We propose a general normalization procedure motivated by the z-score which produces much less biased rankings when applied to citation count and PageRank score. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.08071v1.pdf"}
{"id": "1703.08240", "abstract": "  In this paper we consider the reconstruction problem of photoacoustic tomography (PAT) with a flat observation surface. We develop a direct reconstruction method that employs regularization with wavelet sparsity constraints. To that end, we derive a wavelet-vaguelette decomposition (WVD) for the PAT forward operator and a corresponding explicit reconstruction formula in the case of exact data. In the case of noisy data, we combine the WVD reconstruction formula with soft-thresholding which yields a spatially adaptive estimation method. We demonstrate that our method is statistically optimal for white random noise if the unknown function is assumed to lie in any Besov-ball. We present generalizations of this approach and, in particular, we discuss the combination of vaguelette soft-thresholding with a TV prior. We also provide an efficient implementation of the vaguelette transform that leads to fast image reconstruction algorithms supported by numerical results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.08240v1.pdf"}
{"id": "1703.08986", "abstract": "  We analyze a sample of z-dropout galaxies in the CANDELS GOODS South and UDS fields that have been targeted by a dedicated spectroscopic campaign aimed at detecting their Lyα line. Deep IRAC observations at 3.6 and 4.5 μm are used to determine the strength of optical emission lines affecting these bands at z∼6.5-6.9 in order to i) investigate possible physical differences between Lyα emitting and non-emitting sources; ii) constrain the escape fraction of ionizing photons; iii) provide an estimate of the specific star-formation rate at high redshifts. We find evidence of strong [OIII]+Hβ emission in the average (stacked) SEDs of galaxies both with and without Lyα emission. The blue IRAC [3.6]-[4.5] color of the stack with detected Lyα line can be converted into a rest-frame equivalent width EW([OIII]+Hβ)=1500^+530_-440Å assuming a flat intrinsic stellar continuum. This strong optical line emission enables a first estimate of f_esc≲20", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.08986v3.pdf"}
{"id": "1703.09373", "abstract": "  Small lattice polarons driven by strong external electric fields are considered. A time-dependent Schroedinger equation is integrated directly in time domain. The field agitates ions both directly and through modulation of carrier density. It is found that when the field is in resonance with local ion oscillations, the polaron is liberated from its self-induced trap and the tunneling frequency increases exponentially. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.09373v2.pdf"}
{"id": "1703.09461", "abstract": "  High-dose-rate brachytherapy is a tumor treatment method where a highly radioactive source is brought in close proximity to the tumor. In this paper we develop a simulated annealing algorithm to optimize the dwell times at preselected dwell positions to maximize tumor coverage under dose-volume constraints on the organs at risk. Compared to existing algorithms, our algorithm has advantages in terms of speed and objective value and does not require an expensive general purpose solver. Its success mainly depends on exploiting the efficiency of matrix multiplication and a careful selection of the neighboring states. In this paper we outline its details and make an in-depth comparison with existing methods using real patient data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.09461v1.pdf"}
{"id": "1703.10435", "abstract": "  The family of Multiscale Hybrid-Mixed (MHM) finite element methods has received considerable attention from the mathematics and engineering community in the last few years. The MHM methods allow solving highly heterogeneous problems on coarse meshes while providing solutions with high-order precision. It embeds independent local problems which are responsible for upscaling unresolved scales into the numerical solution. These local contributions are brought together through a global problem defined on the skeleton of the coarse partition. Since the local problems are completely independent, they can be easily computed in parallel. In this paper, we present two simulator prototypes specifically crafted for the MHM methods, which adopt two different implementation strategies: (i) a multi-programming language approach, each language tackling different simulation issues; and (ii) a classical, single-programming language approach. Specifically, we use C++ for numerical computation of the global and local problems in a modular way; for process distribution in the simulator, we adopt the Erlang concurrent language in the first approach, and the MPI standard in the second approach. The aim of exploring these different approaches is twofold: (i) allow for the deployment of the simulator both in high-performance computing (with MPI) and in cloud computing environments (with Erlang); and (ii) pave the way for further exploration of quality attributes related to software productivity and fault-tolerance, which are key to Exascale systems. We present a performance evaluation of the two simulator prototypes taking into account their efficiency. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.10435v1.pdf"}
{"id": "1703.10486", "abstract": "  The layered misfit cobaltate Ca_3Co_4O_9, also known as Ca_2CoO_3[CoO_2]_1.62, is a promising p-type thermoelectric oxide. Employing density functional theory, we study its electronic structure and determine, on the basis of Boltzmann theory within the constant-relaxation-time approximation, the thermoelectric transport coefficients. The dependence on strain and temperature is determined. In particular, we find that the xx-component of the thermopower is strongly enhanced, while the yy-component is strongly reduced, when applying 2", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.10486v1.pdf"}
{"id": "adap-org9712002", "abstract": "  The early-time critical dynamics of continuous, Ising-like phase transitions is studied numerically for two-dimensional lattices of coupled chaotic maps. Emphasis is laid on obtaining accurate estimates of the dynamic critical exponents θ' and z. The critical points of five different models are investigated, varying the mode of update, the coupling, and the local map. Our results suggest that the nature of update is a relevant parameter for dynamic universality classes of extended dynamical systems, generalizing results obtained previously for the static properties. They also indicate that the universality observed for the static properties of Ising-like transitions of synchronously-updated systems does not hold for their dynamic critical properties. ", "pdf_url": "gs://arxiv-dataset/arxiv/adap-org/pdf/9712/9712002v1.pdf"}
{"id": "astro-ph0001098", "abstract": "  It is widely believed that most of the cosmic X-ray background (XRB) is produced by a vast, hitherto undetected population of obscured AGN. Deep X-ray surveys with Chandra and XMM will soon test this hypothesis. Similarly, recent sub-mm surveys with SCUBA have revealed an analogous population of exceptionally luminous, dust-enshrouded star-forming galaxies at high redshift. There is now growing evidence for an intimate link between these obscured populations. There are currently large uncertainties in the models, but several independent arguments lead to the conclusion that a significant fraction of the SCUBA sources (10-30", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0001/0001098v1.pdf"}
{"id": "astro-ph0001465", "abstract": "  I review gamma-ray burst optical/multiwavelength afterglow observations since 1997, when the first counterparts to GRBs were discovered. I discuss what we have learned from multiwavelength observations of GRB afterglows in relation to the `standard' fireball plus relativistic blast-wave models. To first order the `standard' model describes the afterglow observations well, but a wealth of information can be gathered from the deviations of GRB afterglow observations from this `standard' model. These deviations provide information on the nature of the progenitor and on the physics of GRB production. In particular I focus on the possible connection of GRBs to supernovae, on jet and circumstellar wind models, on the early-time afterglow, and on the emission from the reverse shock. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0001/0001465v1.pdf"}
{"id": "astro-ph0002025", "abstract": "  The main goals of the KASCADE (KArlsruhe Shower Core and Array DEtector) experiment are the determination of the energy spectrum and elemental composition of the charged cosmic rays in the energy range around the knee at ca. 5 PeV. Due to the large number of measured observables per single shower a variety of different approaches are applied to the data, preferably on an event-by-event basis. First results are presented and the influence of the high-energy interaction models underlying the analyses is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0002/0002025v1.pdf"}
{"id": "astro-ph0002251", "abstract": "  A new method for the inclusion of ionizing radiation from uniform radiation fields into 3D Smoothed Particle Hydrodynamics (SPHI) simulations is presented. We calculate the optical depth for the Lyman continuum radiation from the source towards the SPHI particles by ray-tracing integration. The time-dependent ionization rate equation is then solved locally for the particles within the ionizing radiation field. Using test calculations, we explore the numerical behaviour of the code with respect to the implementation of the time-dependent ionization rate equation. We also test the coupling of the heating caused by the ionization to the hydrodynamical part of the SPHI code. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0002/0002251v1.pdf"}
{"id": "astro-ph0002475", "abstract": "  ESA and NASA are studying projects having a tremendous return on variable star research. Other national space agencies are also studying or developing projects of smaller costs but with impressive returns. The projects range from global Galactic surveys like the ESA mission GAIA which will give photometric time series for about 1 billion stars, to detailed pulsation modes studies like the CNES mission COROT which could reach a photometric precision lower than 1 ppm. The presentation will emphasize the future astrometric, asteroseismologic and planet detection missions. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0002/0002475v1.pdf"}
{"id": "astro-ph0003236", "abstract": "  Using the exceptional long-term monitoring capabilities of the MACHO project, we present here the optical history of LMC X-2 for a continuous 6-yr period. These data were used to investigate the previously claimed periodicities for this source of 8.15 h and 12.54 d : we find upper amplitude limits of 0.10 mag and 0.09 mag, respectively. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0003/0003236v2.pdf"}
{"id": "astro-ph0003240", "abstract": "  We report BV(RI)c CCD photometric data for a group of seven Cepheid variables in the young, rich cluster NGC 1866 in the Large Magellanic Cloud. The photometry was obtained as part of a program to determine accurate distances to these Cepheids by means of the infrared surface brightness technique, and to improve the LMC Cepheid database for constructing Cepheid PL and PLC relations. Using the new data together with data from the literature, we have determined improved periods for all variables. For five fundamental mode pulsators, the light curves are now of excellent quality and will lead to accurate distance and radius determinations once complete infrared light curves and radial velocity curves for these variables become available. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0003/0003240v1.pdf"}
{"id": "astro-ph0005516", "abstract": "  The radio emission from supermassive black holes in nearby early-type galaxies can be used to test possible explanations for their low luminosities. We calculate the expected contribution from thermal synchrotron emission from hot accretion flows to the high radio frequency observations of NGC 2300, NGC 1399, NGC 4278 and NGC 4594. We find that, in all cases, and in accordance with our previous findings, hot flows accreting close to their Bondi rates overestimate significantly the observed fluxes. This implies that simply assuming a low radiative efficiency for the accreting gas is not enough to explain their low luminosities. Smaller central densities and accretion rates, as expected in the presence of strong mass loss or convection in the flows, can help reconcile the models with observations. We also show that a significant contribution to the high-frequency radio spectra can be due to non-thermal synchrotron emission from the small scale radio jets observed in these systems, allowing for even lower accretion rates in the inflows. We suggest that these outflows or jets may dump significant energy into the surronding medium close to the accretion radius and so reduce the accretion rates onto these systems. We discuss the relationship between the radio flux and black hole mass for the observed sample and its potential importance for probing accretion models. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0005/0005516v1.pdf"}
{"id": "astro-ph0006191", "abstract": "  This paper addresses the question of the observations to be performed with the Optical Monitor (OM) of the X-ray Multi-Mirror Satellite (XMM) under several aspects. First, we discuss XMM-OM's photometric system and its colour transformations towards the standard UBV system. Second, we establish a set of procedures to determine the temperature and the amount of interstellar absorption affecting the observed stars. Last, we address the possibility of isolating quasars in multidimensional colour diagrams based on the XMM-OM filter set. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0006/0006191v1.pdf"}
{"id": "astro-ph0007044", "abstract": "  Photoevaporation driven by the ultraviolet radiation from massive stars severely limits the lifetime of protoplanetary discs around stars formed within stellar clusters. I investigate the resulting influence of clustered environments on the probability of giant planet formation, and show that for clusters as rich, or richer than, Orion, the time available for planet formation is likely to be limited to the length of any delay between low mass and high mass star formation. Under popular models for the formation of massive planets, the fraction of stars with giant planets in rich clusters is expected to be substantially suppressed as compared to less clustered star formation environments. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0007/0007044v2.pdf"}
{"id": "astro-ph0010118", "abstract": "  We explore how the growth rate of spiral disks can be measured via analyses of the scatter in the Tully-Fisher (TF) relation of local and intermediate redshift galaxies. As an initial step, we show it is possible to construct a low-dispersion TF relation for nearly face-on, nearby spirals. We find these spiral disks are non-circular, (a mean ellipticity of 6", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0010/0010118v1.pdf"}
{"id": "astro-ph0010262", "abstract": "  As presented by Nice et al. (2000), long-term timing of the eclipsing binary PSR B1744-24A shows that the orbital period of this system decreases with a time-scale of only   200 Myr. To explain the much faster orbital period decay than that predicted by only emission of the gravitational waves   1000 Myr) we propose that the orbital evolution of this system is also driven by magnetic braking . If magnetic braking is to explain the rapid decay of the orbit, then λcharacterizing the effectiveness of the dynamo action in the stellar convection zone in the magnetic stellar wind formula must be equal to 1. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0010/0010262v1.pdf"}
{"id": "astro-ph0011232", "abstract": "  Two ASCA observations were made of two ultra-luminous compact X-ray sources (ULXs), Source 1 and Source 2, in the spiral galaxy IC 342. In the 1993 observation, Source 2 showed a 0.5–10 keV luminosity of 6 × 10^39 ergs s^-1 (assuming a distance of 4.0 Mpc), and a hard power-law spectrum of photon index ∼ 1.4. As already reported, Source 1 was ∼ 3 times brighter on that occasion, and exhibited a soft spectrum represented by a multi-color disk model of inner-disk temperature ∼ 1.8 keV. The second observation made in February 2000 revealed that Source 1 had made a transition into a hard spectral state, while Source 2 into a soft spectral state. The ULXs are therefore inferred to exhibit two distinct spectral states, and sometimes make transitions between them. These results significantly reinforce the scenario which describes ULXs as mass-accreting black holes. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0011/0011232v1.pdf"}
{"id": "astro-ph0011424", "abstract": "  Stars are most likely to merge or collide in regions of the highest stellar densities, and our own Galactic Center contains many stars packed into a relatively small volume – even the ambient stellar number density in the central 50 pc is quite high,  10^3 stars pc^-3. More striking, the three compact young clusters in this region have central densities as high as 10^6 stars pc^-3. We discuss these extreme environments and the possibility that stellar mergers and collisions have recently occured there. In particular, we predict that at least one massive star in the Arches cluster has already experienced a stellar merger in its short lifetime. Further, the Pistol Star, in the nearby Quintuplet cluster, might owe its apparent relative youth to a rejuvinating stellar merger. Finally, the apparently young stars in the central arcsecond could be products of either collisions, inducing atmospheric stripping, or mergers. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0011/0011424v1.pdf"}
{"id": "astro-ph0103469", "abstract": "  Accreting black holes and neutron stars at luminosities above 0.01 of the critical Eddington luminosity have a lot of similarities, but also drastic differences in their radiation and power density spectra. The efficiency of energy release due to accretion onto a rotating neutron star usually is higher than in the case of a black hole. The theory of the spreading layer on the surface of an accreting neutron star is discussed. It predicts the appearance of two bright belts equidistant from the equator. This layer is unstable and its radiation flux must vary with high frequencies. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0103/0103469v1.pdf"}
{"id": "astro-ph0105361", "abstract": "  We use a wide range of observations to constrain cosmological models possessing a significant asymmetry in the lepton sector, which offer perhaps the best chance of reconciling a critical-density Universe with current observations. The simplest case, with massless neutrinos, fails to fit many experimental data and does not lead to an acceptable model. If the neutrinos have mass of order one electron-volt (which is favoured by some neutrino observations), then models can be implemented which prove a good fit to microwave anisotropies and large-scale structure data. However, taking into account the latest microwave anisotropy results, especially those from Boomerang, we show that the model can no longer accommodate the observed baryon fraction in clusters. Together with the observed acceleration of the present Universe, this puts considerable pressure on such critical-density models. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0105/0105361v1.pdf"}
{"id": "astro-ph0105478", "abstract": "  We have analyzed publicly available RXTE/PCAs archival data of GRS 1915+105 during its burst/flaring state. The burst cycle ranges from 30 to 1300 s. These bursts are different from the type I and type II classical bursts seen in Low Mass X-ray Binaries (LMXBs) in terms of their temporal and spectral properties. We have classified these bursts on the basis of properties observed during the quiescent (low flux) phase. The 2 - 10 Hz QPOs are present during the quiescent phase and disappear during the burst phase of all types of these X-ray bursts. The duration of the quiescent phase can be explained assuming an outflow from the post-shock regions and the catastrophic Compton cooling. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0105/0105478v1.pdf"}
{"id": "astro-ph0107060", "abstract": "  Ground based imaging, imaging polarimetry, and recent Hubble Space Telescope WFPC2 and NICMOS images of protostars have revealed very complex scattered light patterns that cannot be entirely explained by 2-D radiation transfer models. We present here for the first time radiation transfer models of T Tau and IRAS 04016+2610 that are fully 3-D, with the aim of investigating the effects on image morphology of multiple illuminating sources and infalling envelopes that have been shaped by multiple outflows. For T Tau we have constructed scattered light models where the illumination of the surrounding envelope is by a binary with each source surrounded by its own small circumstellar disk or envelope. We find that the asymmetries in the WFPC2 image of T Tau can be reproduced if the disks in the binary system are misaligned, consistent with a recently discovered bipolar outflow believed to originate from the secondary. For IRAS 04016+2610 we find that the observed scattered light pattern can be reproduced by scattering in an envelope with cavities carved by two sets of bipolar outflows, suggestive of an embedded binary system. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0107/0107060v1.pdf"}
{"id": "astro-ph0107225", "abstract": "  X-ray spectroscopy of Seyfert 2 galaxies provides an excellent probe of the circumnuclear environment in active galactic nuclei. The grating experiments on both Chandra and XMM-Newton have now provided the first high resolution spectra of several of the brightest Seyfert 2's. We present Chandra HETG data on Markarian 3 and XMM-Newton RGS data on NGC 1068. In both cases, the spectra are dominated by emission lines due to radiative recombination following photoionization, photoexcitation, and fluorescence. There is no evidence for any significant contribution from collisionally-heated gas. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0107/0107225v1.pdf"}
{"id": "astro-ph0107350", "abstract": "  The rotation periods of the host stars of extrasolar planets have been assessed against those of the Mt. Wilson stars, open cluster stars, and evolutionary stellar models that include rotation. They appear to be normal, modulo certain inconsistencies in various necessary inputs. Selection of candidate planet hosts for radial velocity surveys by low rotation or activity has resulted in a planet host sample skewed towards older stars. Thus, cross-comparisons must be age dependent. However, self-consistent ages are difficult to obtain, and activity ages show signs of systematic errors. There are indications that activity ages ought to be increased for lower-than-solar-mass stars and decreased for higher-than-solar-mass stars. Age uncertainties and a scarcity of measured rotation periods for planet host stars inflate the dispersion in older stars relative to those in open clusters. The presently available rotational models display inadequacies, most notably in producing fast-enough early-type stars. The fact that only one planet host star, τ Boo, strongly suggests tidal spin-up, while of order ten systems suggest orbital circularization is explicable in terms of the differing timescales for these two phenomena. The rotational normalcy of the planet host stars and other considerations suggest that they are not especially different from other main sequence stars and that circumstellar matter and/or planets are probably ubiquitous, at least among sufficiently metal-rich solar-type stars. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0107/0107350v1.pdf"}
{"id": "astro-ph0108351", "abstract": "  We model the reflected spectrum expected from localized magnetic flares above an ionised accretion disk. We concentrate on the case of very luminous magnetic flares above a standard accretion disk extending down to the last stable orbit, and use a simple parameterisation to allow for an X-ray driven wind. Full disk spectra including relativistic smearing are calculated. When fit with the constant density reflection models, these spectra give both a low reflected fraction and a small line width as seen in the hard spectra from Galactic Black Hole Binaries and Active Galactic Nuclei. We fit our calculated spectra to real data from the low/hard state of Nova Muscae and Cyg X-1 and show that these models give comparable χ^2 to those obtained from the constant density reflection models which implied a truncated disk. This explicitally demonstrates that the data are consistent with either magnetic flares above an ionized disk extending down to the last stable orbit around a black hole, or with non-ionized, truncated disks. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0108/0108351v1.pdf"}
{"id": "astro-ph0110240", "abstract": "  From long-term photometry of a VY Scl-type star, V425 Cas, between 1998 and 2000, we discovered a short-term, large-amplitude (up to 1.5 mag) variations. The variation was well represented by a single period of 2.65 d. The large amplitude and the profile of the folded light curve suggest that the dwarf nova-type disk instability is responsible for this variation. The shortness of the period is unprecedented in hydrogen-rich cataclysmic variables. Given the recent emerging evidence that the irradiation from white dwarfs in VY Scl-type systems affect their light behavior, we propose a possibility that this unique variation in V425 Cas can be explained by the combination of the dwarf nova-type disk instability and irradiation. Similar short-period \"outbursts\" have been known in X-ray transients (V518 Per), and helium cataclysmic variables (CR Boo and V803 Cen). We discuss the possibility that these phenomena have a common origin to the unique variation in V425 Cas. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0110/0110240v1.pdf"}
{"id": "astro-ph0110267", "abstract": "  The large collecting area of 4+ metre class telescopes allows atronomers to observe bright objects on faster timescales than previously possible. In order to exploit this capability, we designed a novel read-out mode for use on the 10-m Keck-II telescope on Mauna Kea, Hawaii. This took the form of a continuous read-out mode, enabling us to obtain a target spectrum between 3500 and 8500 Å, with a dispersion of  2.5 Å/pix, every *70 milliseconds*. I present results from 5 nights of observations of Interacting Binaries, using this novel data acquisition system in July 1998. During the run we obtained more than 1.2 million optical spectra, many of which were simultaneous with pointed RXTE observations. This fast spectroscopic capability has allowed us to explore regimes previously only accessible with broadband instruments. I will concentrate on results from the coordinated Keck/RXTE observations, which have revealed interesting correlated variability on timescales from seconds to days. I will also show the results of a spectroscopic-timing analysis of QPOs in Hercules X-1, which shows evidence for the decay of individual blobs of material orbiting the neutron star. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0110/0110267v1.pdf"}
{"id": "astro-ph0110317", "abstract": "  We studied the large-amplitude SU UMa-type dwarf nova V344 Lyr. A combination of our observations and reports to VSNET has yielded an extensive coverage of outbursts between 1994 July and 2001 June. The analysis of this data showed a mean supercycle length of 109.6 d. This value is one of the smallest among known SU UMa-type dwarf novae (except unusual ER UMa-type dwarf novae). The outburst amplitude of V344 Lyr ( 5.5 mag) is found to be much larger than those (3.5 +/- 0.3 mag) of SU UMa-type dwarf novae with similar supercycle lengths. Such a deviation of the amplitude in V344 Lyr is difficult to explain by the inclination effect. The extreme outburst parameters of V344 Lyr would require an additional mechanism to effectively reduce the quiescent luminosity or to increase the outburst frequency. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0110/0110317v1.pdf"}
{"id": "astro-ph0110425", "abstract": "  In this paper we present a numerical study of plasma jets produced by intense laser matter interactions. Through this study we hope to better understand astrophysical jets and their recent experimental simulations in the laboratory. We paid special attention to radiation cooling and the interaction of the jet with ambient gas. Four cases are presented in this paper; two of them deal with the propagation of jets in vacuum, while in the other two the propagation takes place in the ambient gas. Available experimental results are reproduced to good accuracy in the vacuum case. For jets in ambient gas, we find that the existence of the surrounding gas confines the jet into a narrow cylindrical shape so that both the density and temperature of the jet remain high enough for effective radiation cooling. As a result, a collimated plasma jet is formed in these cases. The dimensionless parameters characterizing the laboratory jets and protostellar jets have overlapping domains. We also discuss the cooling lengths for our model and compare them with the corresponding values in the astrophysical jets. A plasma jet in the ambient gas experiment is proposed which is within the reach of present day technology, and can be relevant to astrophysical phenomena. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0110/0110425v2.pdf"}
{"id": "astro-ph0111387", "abstract": "  We present the results of a search for optical counterparts to the two quiescent low mass X-ray binaries (X5 and X7) in the globular cluster 47 Tucanae, using high quality Chandra and HST images. A faint blue (V=21.7; U-V=0.9) star within 0.03\" of the eclipsing system X5 shows variability on both short and long timescales, and is the counterpart of the X-ray source. The colors and variability of this object are consistent with the combination of light from an accretion disk and a red main sequence star (possibly somewhat larger than a normal MS star with similar luminosity). No evidence is found for a star showing either variability or unusual colors near the position of X7, but a probable chance superposition of a star with V=20.25 limits the depth of our search. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0111/0111387v1.pdf"}
{"id": "astro-ph0112358", "abstract": "  I summarize recent work comparing relative distances measured to individual galaxies with independent methods. The comparisons include: ground-based surface brightness fluctuation (SBF) and fundamental plane distances to 170 galaxies, distances predicted from galaxy velocities and the inferred gravity field, HST SBF measurements to seven early-type hosts of Type Ia supernovae, and ties of the Cepheid distance scale to early-type galaxies. Independent calibrations for some methods provide interesting constraints on the Cepheid zero point. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0112/0112358v1.pdf"}
{"id": "astro-ph0112375", "abstract": "  It is known from theory that, by means of a plasma physics approach, it is possible to obtain a simple formula to calculate the approximate height of a meteor (Foschini, 1999). This formula can be used in case of forward scatter of radio waves and has the advantage that it does not depend on the diffusion coefficient. On the other hand, it is possible to apply the formula to a particular type of meteor only (overdense meteor type I), which is a small fraction of the total number observed. We have carried out a statistical analysis of several radio echoes from meteor showers recorded during last years by a radio observer located in Belgium. Results are compared and discussed with those obtained with other methods and available in literature. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0112/0112375v1.pdf"}
{"id": "astro-ph0112457", "abstract": "  We investigate the impact of peculiar velocity effects due to the motion of the solar system relative to the microwave background (CMB) on high resolution CMB experiments. It is well known that on the largest angular scales the combined effects of Doppler shifts and aberration are important; the lowest Legendre multipoles of total intensity receive power from the large CMB monopole in transforming from the CMB frame. On small angular scales aberration dominates and is shown here to lead to significant distortions of the total intensity and polarization multipoles in transforming from the rest frame of the CMB to the frame of the solar system. We provide convenient analytic results for the distortions as series expansions in the relative velocity of the two frames, but at the highest resolutions a numerical quadrature is required. Although many of the high resolution multipoles themselves are severely distorted by the frame transformations, we show that their statistical properties distort by only an insignificant amount. Therefore, cosmological parameter estimation is insensitive to the transformation from the CMB frame (where theoretical predictions are calculated) to the rest frame of the experiment. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0112/0112457v1.pdf"}
{"id": "astro-ph0203139", "abstract": "  The recent announcement that sodium absorption has been observed in the atmosphere of HD209458b, the only EGP observed to transit its parent star, is the first direct detection of an EGP atmosphere. We explore the possibility that neutral sodium is not in local thermodynamic equilibrium (LTE) in the outer atmosphere of irradiated EGPs and that the sodium concentration may be underestimated by models that make the LTE assumption. Our results indicate that it may not be necessary to invoke excessive photoionization, low metallicity, or even high altitude clouds to explain the observations. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0203/0203139v1.pdf"}
{"id": "astro-ph0203310", "abstract": "  In this review talk I discuss the important issues of AGN research and how the new generation of X-ray observatories can help to constrain the physics of AGN. I also present a biased list of the new XMM-Newton and Chandra discoveries and how theyhave altered our view of AGN. I also present a set of what are the new types of observations that need to be performed to make significant progress in this field. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0203/0203310v1.pdf"}
{"id": "astro-ph0204247", "abstract": "  We use HST broad band images, VLA and VLBI continuum data to study the three dimensional orientation of jets relative to nuclear dust disks in 20 radio galaxies. The comparison between the position angles of the jets with those of the dust disks major axes shows a wide distribution, suggesting that they are not aligned preferentially perpendicular to each other. We use a statistical technique to determine the 3 dimensional distribution of angles between jets and dust disks rotation axes. This analysis shows that the observations are consistent with jets homogeneously distributed over a large region, extending over polar caps of 55 degrees to 77 degrees, but seem to avoid lying close to the plane of the dust disks. We argue that the lack of close alignment between jets and dust disks axes is not likely to be caused by feeding the nucleus with gas from mergers originated from random directions. We suggest that the misalignment can be due by a warping mechanism in the accretion disk, like self-irradiation instability or the Bardeen-Petterson effect, or that the gravitational potential in the inner regions of the galaxy is misaligned with respect to that of the dust disk. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0204/0204247v1.pdf"}
{"id": "astro-ph0205102", "abstract": "  We report the detection of the polar CE Gru in X-rays for the first time. We find evidence for a dip seen in the hard X-ray light curve which we attribute to the accretion stream obscuring the accretion region in the lower hemisphere of the white dwarf. The X-ray spectrum can be fitted using only a shock model: there is no distinct soft X-ray component. We suggest that this is because the reprocessed component is cool enough so that it is shifted into the UV. We determine a mass for the white dwarf of  1.0Msun. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0205/0205102v1.pdf"}
{"id": "astro-ph0206091", "abstract": "  We present a catalogue of the 322 damped Lyman alpha absorbers taken from the literature. All damped Lyman alpha absorbers are included, with no selection on redshift or quasar magnitude. Of these, 123 are candidates and await confirmation using high resolution spectroscopy. For all 322 objects we catalogue the radio properties of the background quasars, where known. Around 60 quasars have radio flux densities above 0.1 Jy and approximately half of these have optical magnitudes brighter than V = 18. This compilation should prove useful in several areas of extragalactic/cosmological research. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0206/0206091v1.pdf"}
{"id": "astro-ph0207377", "abstract": "  We present the first analysis of three-dimensional genus statistics for the SDSS EDR galaxy sample. Due to the complicated survey volume and the selection function, analytic predictions of the genus statistics for this sample are not feasible, therefore we construct extensive mock catalogs from N-body simulations in order to compare the observed data with model predictions. This comparison allows us to evaluate the effects of a variety of observational systematics on the estimated genus for the SDSS sample, including the shape of the survey volume, the redshift distortion effect, and the radial selection function due to the magnitude limit. The observed genus for the SDSS EDR galaxy sample is consistent with that predicted by simulations of a Λ-dominated spatially-flat cold dark matter model. Standard (Ω_0=1) cold dark matter model predictions do not match the observations. We discuss how future SDSS galaxy samples will yield improved estimates of the genus. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0207/0207377v2.pdf"}
{"id": "astro-ph0207485", "abstract": "  The nearby Mira-like variable L2 Pup is shown to be undergoing an unprecedented dimming episode. The stability of the period rules out intrinsic changes to the star, leaving dust formation along the line of sight as the most likely explanation. Episodic dust obscuration events are fairly common in carbon stars but have not been seen in oxygen-rich stars. We also present a 10-micron spectrum, taken with the Japanese IRTS satellite, showing strong silicate emission which can be fitted with a detached, thin dust shell, containing silicates and corundum. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0207/0207485v1.pdf"}
{"id": "astro-ph0208066", "abstract": "  The black-hole/accretion-disk paradigm for active galactic nuclei (AGNs) is now reasonably secure, but there are still important unresolved issues, some of which will require the capabilities of an 8 to 10-m class UV/optical space-based telescope. Imaging spectroscopy with a diffraction-limited large telescope will be required to measure AGN black-hole masses from stellar dynamics for direct comparison with reverberation mapping-based masses. High spectral resolution in the UV is required to determine the mass and kinetic energy of the outflows observed in the absorption spectra of AGNs and to understand the energetics of the accretion process. As with ground-based astronomy, however, effective use of a large UV/optical space telescope requires complementary smaller facility instruments; a meter-class UV spectroscopic telescope, for example, can fit into a Medium Explorer budget. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0208/0208066v1.pdf"}
{"id": "astro-ph0208586", "abstract": "  In this paper, we present preliminary results on the stability of massless particles in two and three-planet systems. The results of our study may be used to address questions concerning the stability of terrestrial planets in these systems and also the trapping of particles in resonances with the planets. The possibility of the existence of islands of stability and/or instability at different regions in multi-body systems and their probable correspondence to certain resonances are also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0208/0208586v1.pdf"}
{"id": "astro-ph0209061", "abstract": "  It has been shown that there is a possible mass-period correlation for extrasolar planets from the current observational data and this correlation is, in fact, related to the absence of massive close-in planets, which are strongly influenced by the tidal interaction with the central star. We confirm that the model in Pätzold     Rauer (2002) is a good approximation for the explanation of the absence of massive close-in planets. We thus further determine the minimum possible semimajor axis for these planets to be detected during their lifetime and also study their migration time scale at different semimajor axes by the calculations of tidal interaction. We conclude that the mass-period correlation at the time when these planets were just formed was less tight than it is now observed if these orbital migrations are taken into account. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0209/0209061v1.pdf"}
{"id": "astro-ph0209494", "abstract": "  Most models of dark energy predict the beginning of the accelerated epoch at z <= 1. However, there are no observational or theoretical evidences in favor of such a recent start of the cosmic acceleration. In fact, a model of dark energy coupled to dark matter is explicitely constructed that a) is accelerated even at high z; b) allows structure formation during acceleration; and c) is consistent with the type Ia supernovae Hubble diagram, including the farthest known supernova SN1997ff at z 1.7 . It is shown that the accelerated epoch in this model could have started as early as z 5. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0209/0209494v3.pdf"}
{"id": "astro-ph0210051", "abstract": "  The present-day chemical and dynamical properties of the Milky Way are signatures of the Galaxy's formation and evolution. Using a self consistent chemodynamical evolution code we examine these properties within the currently favoured paradigm for galaxy formation - hierarchical clustering within a CDM cosmology. Our Tree N-body/Smoothed Particle Hydrodynamics code includes a self-consistent treatment of gravity, hydrodynamics, radiative cooling, star formation, supernova feedback and chemical enrichment. Two models are described which explore the role of small-scale density perturbations in driving the evolution of structure within the Milky Way. The relationship between metallicity and kinematics of halo stars are quantified and the implications for galaxy formation discussed. While high-eccentricity halo stars have previously been considered a signature of “rapid collapse”, we suggest that many such stars may have come from recently accreted satellites. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0210/0210051v1.pdf"}
{"id": "astro-ph0210166", "abstract": "  One of two approaches to implementing NASA's Terrestrial Planet Finder is to build a space telescope that utilizes the techniques of coronagraphy and apodization to suppress diffraction and image exo-planets. We present a method for calculation of a telescope's apodizer which suppresses the side lobes of the image of a star so as to optimally detect an Earth-like planet. Given the shape of a telescope's aperture and given a search region for a detector, we solve an integral equation to determine an amplitude modulation (an apodizer) which suppresses the star's energy in the focal plane search region. The method is quite general and yields as special cases the product apodizer reported by Nisenson and Papaliolios (2001) and the Prolate spheroidal apodizer of Kasdin et al (2002), and Aime et al (2002). We show computer simulations of the apodizers and the corresponding point spread functions for various aperture-detector configurations. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0210/0210166v2.pdf"}
{"id": "astro-ph0211076", "abstract": "  We have numerically investigated the long term dynamical behavior of known Centaurs. This class of objects is thought to constitute the transitional population between the Kuiper Belt and the Jupiter-family comets (JFCs). In our study, we find that over their dynamical lifetimes, these objects diffuse into the JFCs and other sinks, and also make excursions into the Scattered Disk, but (not surprisingly) do not diffuse into the parameter space representing the main Kuiper Belt. These Centaurs spend most of their dynamical lifetimes in orbits of eccentricity 0.2-to-0.6 and perihelion distance 12-to-30 AU. Their orbital evolution is characterized by frequent close encounters with the giant planets. Most of these Centaurs will escape from the solar system (or enter the Oort Cloud), while a fraction will enter the JFC population and a few percent will impact a giant planet. Their median dynamical lifetime is 9 Myr, although there is a wide dispersion in lifetimes, ranging from less than 1 Myr to more than 100 Myr. We find the dynamical evolution of this sample of Centaurs to be less orderly than the planet-to-planet \"hand-off\" described in previous investigations. We discuss the implications of our study for the spatial distribution of the Centaurs as a whole. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0211/0211076v2.pdf"}
{"id": "astro-ph0212215", "abstract": "  High-precision spectrophotometry is highly desirable in detecting and characterizing close-in extrasolar planets to learn about their makeup and temperature. For such a goal, a modest-size telescope with a simple low-resolution spectroscopic instrument is potentially as good or better than a complex general purpose spectrograph since calibration and removal of systematic errors is expected to dominate. We use a transmission grating placed in front of an imaging CCD camera on Steward Observatory's Kuiper 1.5 m telescope to provide a high signal-to-noise, low dispersion visible spectrum of the star HD 209458. We attempt to detect the reflected light signal from the extra-solar planet HD 209458b by differencing the signal just before and after secondary occultation. We present a simple data reduction method and explore the limits of ground based low-dispersion spectrophotometry with a diffraction grating. Reflected light detection levels of 0.1", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0212/0212215v1.pdf"}
{"id": "astro-ph0212476", "abstract": "  In view of the current efforts to extend the KASCADE experiment (KASCADE-Grande) for observations of Extensive Air Showers (EAS) of primary energies up to 1 EeV, the features of muon arrival time distributions and their correlations with other observable EAS quantities have been scrutinised on basis of high-energy EAS, simulated with the Monte Carlo code CORSIKA and using in general the QGSJET model as generator. Methodically various correlations of adequately defined arrival time parameters with other EAS parameters have been investigated by invoking non-parametric methods for the analysis of multivariate distributions, studying the classification and misclassification probabilities of various observable sets. It turns out that adding the arrival time information and the multiplicity of muons spanning the observed time distributions has distinct effects improving the mass discrimination. A further outcome of the studies is the feature that for the considered ranges of primary energies and of distances from the shower axis the discrimination power of global arrival time distributions referring to the arrival time of the shower core is only marginally enhanced as compared to local distributions referring to the arrival of the locally first muon. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0212/0212476v1.pdf"}
{"id": "astro-ph0212478", "abstract": "  A two-week campaign of high-resolution imaging of the centre of M15 using the tip/tilt correcting TRIFFID-2 camera, followed by analysis with ISIS (image matching     subtraction software), has produced the most sensitive survey to date of variable stars in the central  1x1 arcmin^2 - a total of 48 were detected -, and constrains the size of the dwarf nova population. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0212/0212478v1.pdf"}
{"id": "astro-ph0212541", "abstract": "  We discuss a concept of off-centred cavity supernova explosion as applied to neutron star/supernova remnant associations and show how this concept could be used to preclude the anti-humane decapitating the Duck (G5.4-1.2 + G5.27-0.9) and dismembering the Swan (Cygnus Loop), as well as to search for a stellar remnant associated with the supernova remnant RCW86. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0212/0212541v1.pdf"}
{"id": "astro-ph0301237", "abstract": "  The spectroscopic and spectropolarimetric variability of the peculiar variable V838 Monocerotis during the brighter phases of its multiple outbursts in 2002 is presented. Significant line profile variability of Hα and Si II 6347.10Å    6371.36Åoccurred in spectra obtained between 2002 February 5 and 2002 March 14, and a unique secondary absorption component was observed near the end of this time period. Our observations also suggest that multiple shifts in ionization states occurred during the outbursts. Spectropolarimetric observations reveal that V838 Mon exhibited both intrinsic and interstellar polarization components during the initial stages of the second outburst, indicating the presence of an asymmetric geometry; however, the intrinsic component had significantly declined by February 14. We determine the interstellar polarization to be P_max = 2.746 ± 0.011", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0301/0301237v1.pdf"}
{"id": "astro-ph0303205", "abstract": "  Precise efforts in theoretical astrophysics are needed to fully understand the mechanisms that govern the structure, stability, dynamics, formation, and evolution of differentially rotating stars. Direct computation of the physical attributes of a star can be facilitated by the use of highly compact azimuthal and separation angle Fourier formulations of the Green's functions for the linear partial differential equations of mathematical physics. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0303/0303205v1.pdf"}
{"id": "astro-ph0303393", "abstract": "  Radio continuum emission at 1.4 GHz was used to identify active galaxies in a sample of 20 nearby Abell clusters. The radio emission indicates either an active galactic nucleus or current star formation, and optical spectroscopy was used to evaluate which of these dominates for each of the radio-selected galaxies. In an analysis which parallels the blue fractions of Butcher-Oemler studies, we calculated radio galaxy fractions for the clusters. One cluster in particular shows a dramatic increase in activity relative to the others: the cluster-cluster merger Abell 2255. We compare the results for Abell 2255 with those for Abell 2256 to assess the role of cluster-cluster mergers on the star formation activity of member galaxies. From these clusters, as well as several identified in other studies, a picture emerges in which substructure and cluster dynamical activity are of great importance in understanding evolutionary phenomenon such as the Butcher-Oemler Effect. Increased fractions of active galaxies (be they the blue galaxies of Butcher-Oemler studies or radio galaxies as discussed here) naturally result as clusters are built through mergers of smaller groups in hierarchical formation scenarios. The observed spread in fractions of active galaxies at any given redshift reflects the spread in cluster dynamical state. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0303/0303393v1.pdf"}
{"id": "astro-ph0304146", "abstract": "  The Low Frequency Instrument on board the ESA Planck satellite is coupled to the Planck 1.5 meter off-axis dual reflector telescope by an array of 27 corrugated feed horns operating at 30, 44, 70, and 100 GHz. We briefly present here a detailed study of the optical interface devoted to optimize the angular resolution (10 arcmin at 100 GHz as a goal) and at the same time to minimize all the systematics coming from the sidelobes of the radiation pattern. Through optical simulations, we provide shapes, locations on the sky, angular resolutions, and polarization properties of each beam. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0304/0304146v1.pdf"}
{"id": "astro-ph0304419", "abstract": "  Weak gravitational lensing provides a unique method to directly map the dark matter in the universe and measure cosmological parameters. Current weak lensing surveys are limited by the atmospheric seeing from the ground and by the small field of view of existing space telescopes. We study how a future wide-field space telescope can measure the lensing power spectrum and skewness, and set constraints on cosmological parameters. The lensing sensitivity was calculated using detailed image simulations and instrumental specifications studied in earlier papers in this series. For instance, the planned SuperNova/Acceleration Probe (SNAP) mission will be able to measure the matter density parameter Omega_m and the dark energy equation of state parameter w with precisions comparable and nearly orthogonal to those derived with SNAP from supernovae. The constraints degrade by a factor of about 2 if redshift tomography is not used, but are little affected if the skewness only is dropped. We also study how the constraints on these parameters depend upon the survey geometry and define an optimal observing strategy. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0304/0304419v2.pdf"}
{"id": "astro-ph0304421", "abstract": "  The local axisymmetric stability of hydrodynamical and magnetized, nearly-Keplerian gaseous accretion disks around non-rotating black holes is examined in the vicinity of the classical marginally-stable orbit (at radii   R_ms). An approximate Paczynski-Wiita pseudo-Newtonian potential is used. Hydrodynamical disks are linearly unstable inside a radius which differs slightly from the classical R_ms value because of finite pressure and radial stratification effects. Linear stresses associated with unstable hydrodynamical modes vanish exactly at the radius of marginal stability and are generally positive inside of that radius. When a magnetic field is introduced, however, the concept of radius of marginal stability becomes largely irrelevant because there are linearly unstable magneto-rotational modes everywhere. Associated linear stresses are positive and continuous across the region of hydrodynamical marginal stability, even for large-scale \"hydro-like\" modes subject only to weak magnetic tension. This conclusion is valid for arbitrarily thin disks (in ideal MHD) and it does not require a large-scale \"radially-connecting\" magnetic field. Results on hydrodynamical diskoseismic modes trapped in deep relativistic potential wells should be revised to account for the short-wavelength Alfven-like behavior of inertio-gravity waves in magnetized disks. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0304/0304421v2.pdf"}
{"id": "astro-ph0306334", "abstract": "  We present initial XMM-Newton EPIC observations of the prototypical starburst galaxy M82. The superwind is seen to extend continuously from the starburst region to the X-ray emission associated with the Halpha 'cap'. We also find evidence for a ridge feature, probably associated with the superwind interacting with an HI streamer. Narrow band images, centred on individual X-ray lines, show differences in morphology, with higher energy lines being less spatially extended, and a systematic shift with energy in the region of peak emission. Spectral fits with two thermal and one power-law component provide a good fit to the spectra of the nuclear and inner wind regions, indicating a multiphase superwind. We discuss the implications of these observations on our understanding of superwinds. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0306/0306334v1.pdf"}
{"id": "astro-ph0307305", "abstract": "  Low light level charge coupled devices (L3CCDs) have recently been developed, incorporating on-chip gain. They may be operated to give an effective readout noise much less than one electron by implementing an on-chip gain process allowing the detection of individual photons. However, the gain mechanism is stochastic and so introduces significant extra noise into the system. In this paper we examine how best to process the output signal from an L3CCD so as to minimize the contribution of stochastic noise, while still maintaining photometric accuracy.   We achieve this by optimising a transfer function which translates the digitised output signal levels from the L3CCD into a value approximating the photon input as closely as possible by applying thresholding techniques. We identify several thresholding strategies and quantify their impact on photon counting accuracy and effective signal-to-noise.   We find that it is possible to eliminate the noise introduced by the gain process at the lowest light levels. Reduced improvements are achieved as the light level increases up to about twenty photons per pixel and above this there is negligible improvement. Operating L3CCDs at very high speeds will keep the photon flux low, giving the best improvements in signal-to-noise ratio. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0307/0307305v1.pdf"}
{"id": "astro-ph0309028", "abstract": "  Our knowledge of the high-energy emission spectra from black-hole candidates has increased enormously with missions like BeppoSAX and RossiXTE, thanks to their broad-band window. I present the main and most solid points of this current knowledge, both in terms of detailed spectral modeling of X-ray broad-band spectra, and more generally in relation to the \"black-hole state paradigm\", which links spectral and timing properties of accretion disks. Finally, through the discussion of recent results on two systems, XTE J1650-500 and GX 339-4, I present evidence for a new view of the state paradigm. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0309/0309028v1.pdf"}
{"id": "astro-ph0309423", "abstract": "  The angular power spectrum of the Sunyaev-Zeldovich (SZ) effect is calculated in the ΛCDM cosmological model with the aim of investigating its detailed dependence on the cluster population, gas morphology, and gas evolution. We calculate the power spectrum for three different mass functions, compute it within the framework of isothermal and polytropic gas distributions, and explore the effect of gas evolution on the magnitude and shape of the power spectrum. We show that it is indeed possible to explain the `excess' power measured by the CBI experiment on small angular scales as originating from the SZ effect without (arbitrary) rescaling the value of σ_8, the mass variance parameter. The need for a self-consistent choice of the basic parameters characterizing the cluster population is emphasized. In particular, we stress the need for a consistent choice of the value of σ_8 extracted from fitting theoretical models for the mass function to the observed cluster X-ray temperature function, such that it agrees with the mass-temperature relation used to evaluate the cluster Comptonization parameter. Our treatment includes the explicit spectral dependence of the thermal component of the effect, which we calculate at various frequencies. We find appreciable differences between the non-relativistic and relativistic predictions for the power spectrum even for this superposed contribution from clusters at the full range of gas temperatures. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0309/0309423v1.pdf"}
{"id": "astro-ph0310043", "abstract": "  I present the results of time-resolved photometry of a selection of central stars of planetary nebulae. The study reveals periodic variability in two of the eight central stars observed, those of NGC 6026 and NGC 6337. The variability matches that expected from a binary system in which a hot primary irradiates a cooler secondary star. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0310/0310043v1.pdf"}
{"id": "astro-ph0310636", "abstract": "  Ultrahigh energy neutrinos can provide important information about the distant astronomical objects and the origin of the Universe. Precise knowledge about their interactions and production rates is essential for estimating background, expected fluxes and detection probabilities. In this paper we review the applications of the high energy QCD to the calculations of the interaction cross sections of the neutrinos. We also study the production of the ultrahigh energy neutrinos in the atmosphere due to the charm and beauty decays. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0310/0310636v1.pdf"}
{"id": "astro-ph0310698", "abstract": "  Using high-resolution, high quality spectra we investigate the presence of ^6Li in two lithium-poor stars that host extrasolar planetary systems. We present improved atomic and molecular line lists for the region in the vicinity of the lithium line at 6707.8 Å, and we produce an excellent fit to the solar spectrum. From line profile fitting, we find results consistent with no ^6Li in either of the lithium-poor planet-bearing stars or in three comparison stars with and without planets, and 1-σ upper limits of 0.04 for the isotopic ratios of the two lithium-poor stars give an upper limit of 0.3 Jupiter masses of material with primordial abundances that could have been recently deposited in their outer layers. Our results suggest that post-main sequence accretion of planets or planetary material that is undepleted in lithium is uncommon. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0310/0310698v1.pdf"}
{"id": "astro-ph0310781", "abstract": "  We present a compilation of PRONAOS-based results concerning the temperature dependence of the dust submillimeter spectral index, including data from Galactic cirrus, star-forming regions, dust associated to a young stellar object, and a spiral galaxy. We observe large variations of the spectral index (from 0.8 to 2.4) in a wide range of temperatures (11 to 80 K). These spectral index variations follow a hyperbolic-shaped function of the temperature, high spectral indices (1.6-2.4) being observed in cold regions (11-20 K) while low indices (0.8-1.6) are observed in warm regions (35-80 K). Three distinct effects may play a role in this temperature dependence: one is that the grain sizes change in dense environments, another is that the chemical composition of the grains is not the same in different environments, a third one is that there is an intrinsic dependence of the dust spectral index on the temperature due to quantum processes. This last effect is backed up by laboratory measurements and could be the dominant one.   We also briefly present a joint analysis of WMAP dust data together with COBE/DIRBE and COBE/FIRAS data. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0310/0310781v1.pdf"}
{"id": "astro-ph0311322", "abstract": "  The radial velocities of the 13 globular clusters in the Large Magellanic Cloud have a dispersion of 28 km s^-1 relative to the HI rotation curve of the LMC, compared to a dispersion of 30 km s^-1 with regard to the mean globular cluster velocity. This shows that, contrary to a suggestion by Schommer et al. (1992), one cannot yet rule out the possibility that the LMC globular clusters formed in a pressure supported halo, rather than in rotating disk. The globular clusters in the LMC may therefore, after all, exhibit a relationship between age and kinematics that is similar to that of the clusters in M33. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0311/0311322v1.pdf"}
{"id": "astro-ph0311389", "abstract": "  The Milagro telescope monitors the northern sky for 100 GeV to 100 TeV transient emission through continuous very high energy wide-field observations. The large effective area and  100 GeV energy threshold of Milagro allow it to detect very high energy (VHE) gamma-ray burst emission with much higher sensitivity than previous instruments and a fluence sensitivity at VHE energies comparable to that of dedicated gamma-ray burst satellites at keV to MeV energies. Even in the absence of a positive detection, VHE observations can place important constraints on gamma-ray burst (GRB) progenitor and emission models. We present limits on the VHE flux of 40 s – 3 h duration transients nearby to earth, as well as sensitivity distributions which have been corrected for gamma-ray absorption by extragalactic background light and cosmological effects. The sensitivity distributions suggest that the typical intrinsic VHE fluence of GRBs is similar or weaker than the keV – MeV emission, and we demonstrate how these sensitivity distributions may be used to place observational constraints on the absolute VHE luminosity of gamma-ray bursts for any GRB emission and progenitor model. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0311/0311389v2.pdf"}
{"id": "astro-ph0311454", "abstract": "  Winds from AGN and quasars will form large amounts of dust, as the cool gas in these winds passes through the (pressure, temperature) region where dust is formed in AGB stars. Conditions in the gas are benign to dust at these radii. As a result quasar winds may be a major source of dust at high redshifts, obviating a difficulty with current observations, and requiring far less dust to exist at early epochs. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0311/0311454v1.pdf"}
{"id": "astro-ph0311570", "abstract": "  Most of the proposed associations between magnetars and supernova remnant suffer from age problems. Usually, supernova remnants ages are determined from an approximation of the Sedov-Taylor phase relation between radius and age, for a fixed energy of the explosion   10^51 erg. Those ages do not generally agree with the characteristic ages of the (proposed) associated magnetars. We show quantitatively that, by taking into account the energy injected on the supernova remnant by magnetar spin-down, a faster expansion results, improving matches between characteristic ages and supernova remnants ages. However, the magnetar velocities inferred from observations would inviabilize some associations. Since characteristic ages may not be good age estimators, their influence on the likelihood of the association may not be as important.   In this work we present simple numerical simulations of supernova remnants expansion with internal magnetars, and apply it to the observed objects. A short initial spin period, thought to be important for the very generation of the magnetic field, is also relevant for the modified expansion of the remnant. We next analyze all proposed associations case-by-case, addressing the likelyhood of each one, according to this perspective. We consider a larger explosion energy and reasses the characteristic age issue, and conclude that about 50", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0311/0311570v2.pdf"}
{"id": "astro-ph0312060", "abstract": "  We have performed 2.5-dimensional general relativistic magnetohydrodynamic (MHD) simulations of the gravitational collapse of a magnetized rotating massive star as a model of gamma ray bursts (GRBs). This simulation showed the formation of a disk-like structure and the generation of a jet-like outflow inside the shock wave launched at the core bounce. We have found the jet is accelerated by the magnetic pressure and the centrifugal force and is collimated by the pinching force of the toroidal magnetic field amplified by the rotation and the effect of geometry of the poloidal magnetic field. The maximum velocity of the jet is mildly relativistic (∼ 0.3 c). ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0312/0312060v1.pdf"}
{"id": "astro-ph0312121", "abstract": "  We present preliminary results of an observational campaign devoted at establishing the influence of chemical composition on the Cepheid Period-Luminosity relation. The data are in good agreement with theoretical predictions based on non-linear convective models, suggesting a fairly strong dependence of the Period-Luminosity relation on metallicity in the sense of more metal rich stars being intrinsically fainter than otherwise expected. Our data indicate that the error on the inferred distance can be as large as 10", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0312/0312121v1.pdf"}
{"id": "astro-ph0312349", "abstract": "  We derive an analytic solution for the minimization problem in the geometric Baade-Wesselink method. This solution allows deriving the distance and mean radius of a pulsating star by fitting its velocity curve and angular diameter measured interferometrically. The method also provide analytic solutions for the confidence levels of the best fit parameters, and accurate error estimates for the Baade-Wesselink solution. Special care is taken in the analysis of the various error sources in the final solution, among which the uncertainties due to the projection factor, the limb darkening and the velocity curve. We also discuss the importance of the phase shift between the stellar lightcurve and the velocity curve as a potential error source in the geometric Baade-Wesselink method. We finally discuss the case of the Classical Cepheid zeta Gem, applying our method to the measurements derived with the Palomar Testbed Interferometer. We show how a careful treatment of the measurement errors can be potentially used to discriminate between different models of limb darkening using interferometric techniques. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0312/0312349v1.pdf"}
{"id": "astro-ph0312534", "abstract": "  The Integrated Sachs-Wolfe effect is studied in non-standard cosmologies. By considering flat universes with a non-fluctuating dark energy component, it is shown how the quadrupole power can be suppressed by atypical evolution of the scale factor. For example, a brief period of non-standard evolution at a high redshift can suppress the quadrupole significantly. The effect on the overall normalization of the CMB power spectrum is also discussed. Non-standard cosmologies can affect the overall normalization significantly and enhance the primordial fluctuations. The possibility of constraining such non-standard models with CMB and independent measures of σ_8, is considered. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0312/0312534v1.pdf"}
{"id": "astro-ph0402652", "abstract": "  We derive the fraction of blue galaxies in a sample of clusters at z < 0.11 and the general field at the same redshift. The value of the blue fraction is observed to depend on the luminosity limit adopted, cluster-centric radius and, more generally, local galaxy density, but it does not depend on cluster properties. Changes in the blue fraction are due to variations in the relative proportions of red and blue galaxies but the star formation rate for these two galaxy groups remains unchanged. Our results are most consistent with a model where the star formation rate declines rapidly and the blue galaxies tend to be dwarfs and do not favour mechanisms where the Butcher-Oemler effect is caused by processes specific to the cluster environment. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0402/0402652v1.pdf"}
{"id": "astro-ph0403283", "abstract": "  Saturn's largest satellite, Titan, transited the Crab Nebula on 5 January 2003. We observed this astronomical event with the Chandra X-ray Observatory. An “occultation shadow” has clearly been detected and is found to be larger than the diameter of Titan's solid surface. The difference gives a thickness for Titan's atmosphere of 880 ± 60 km. This is the first measurement of Titan's atmospheric extent at X-ray wavelengths. The value measured is consistent with or slightly larger than those estimated from earlier Voyager observations at other wavelengths. We discuss the possibility of temporal variations in the thickness of Titan's atmosphere. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0403/0403283v1.pdf"}
{"id": "astro-ph0403378", "abstract": "  Quartessence is one of the alternatives to Lambda-CDM that has lately attracted considerable interest. According to this unifying dark matter/energy scenario, the Universe evolved from an early non-relativistic matter-dominated phase to a more recent accelerated expansion phase, driven by a single fluid component. Recently, it has been shown that some problems of the quartessence model, such as the existence of instabilities and oscillations in the matter power spectrum, can be avoided if a specific type of intrinsic entropy perturbation is considered. In the present article we explore the role of skewness in constraining this non-adiabatic scenario. We show that non-adiabatic quartessence and quintessence have different signatures for the skewness of the density distribution on large scales and suggest that this quantity might prove helpful to break possible degeneracies between them. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0403/0403378v1.pdf"}
{"id": "astro-ph0404075", "abstract": "  I compare an aggressive ground-based gravitational microlensing survey for terrestrial planets to a space-based survey. The Ground-based survey assumes a global network of very wide field-of-view  2m telescopes that monitor fields in the central Galactic bulge. I find that such a space-based survey is  100 times more effective at detecting terrestrial planets in Earth-like orbits. The poor sensitivity of the ground-based surveys to low-mass planets is primarily due to the fact that the main sequence source stars are unresolved in ground-based images of the Galactic bulge. This gives rise to systematic photometry errors that preclude the detection of most of the planetary light curve deviations for low mass planets. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0404/0404075v1.pdf"}
{"id": "astro-ph0405246", "abstract": "  Spectral variability in different energy bands of X-rays from Cyg X-1 in different states is studied with RXTE observations and time domain approaches. In the hard tail of energy spectrum above ∼ 10 keV, average peak aligned shots are softer than the average steady emission and the hardness ratio decreases when the flux increases during a shot for all states. In regard to a soft band lower ∼ 10 keV, the hardness in the soft state varies in an opposite way: it peaks when the flux of the shot peaks. For the hard and transition states, the hardness ratio in respect to a soft band during a shot is in general lower than that of the steady component and a sharp rise is observed at about the shot peak. For the soft state, the correlation coefficient between the intensity and hardness ratio in the hard tail is negative and decreases monotonically as the timescale increases from 0.01 s to 50 s, which is opposite to that in regard to a soft band. For the hard and transition states, the correlation coefficients are in general negative and have a trend of decrease with increasing timescale. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0405/0405246v1.pdf"}
{"id": "astro-ph0405541", "abstract": "  In the light of several recent developments we revisit the phenomenon of galactic stellar disk truncations. Even 25 years since the first paper on outer breaks in the radial light profiles of spiral galaxies, their origin is still unclear. The two most promising explanations are that these 'outer edges' either trace the maximum angular momentum during the galaxy formation epoch, or are associated with global star formation thresholds. Depending on their true physical nature, these outer edges may represent an improved size characteristic (e.g., as compared to D_25) and might contain fossil evidence imprinted by the galaxy formation and evolutionary history. We will address several observational aspects of disk truncations: their existence, not only in normal HSB galaxies, but also in LSB and even dwarf galaxies; their detailed shape, not sharp cut-offs as thought before, but in fact demarcating the start of a region with a steeper exponential distribution of starlight; their possible association with bars; as well as problems related to the line-of-sight integration for edge-on galaxies (the main targets for truncation searches so far). Taken together, these observations currently favour the star-formation threshold model, but more work is necessary to implement the truncations as adequate parameters characterising galactic disks. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0405/0405541v3.pdf"}
{"id": "astro-ph0406171", "abstract": "  We present observations of the starburst galaxy NGC 7714 with the Infrared Spectrograph IRS on board the Spitzer Space Telescope. The spectra yield a wealth of ionic and molecular features that allow a detailed characterization of its properties. NGC 7714 has an HII region-like spectrum with strong PAH emission features. We find no evidence for an obscured active galactic nucleus, and with [NeIII]/[NeII] 0.73, NGC7714 lies near the upper end of normal-metallicity starburst galaxies. With very little slicate absorption and a temperature of the hottest dust component of 340K, NGC 7714 is the perfect template for a young, unobscured starburst ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0406/0406171v2.pdf"}
{"id": "astro-ph0406258", "abstract": "  In this paper,We present a simple relativistic approach to analyze the flux striking the disk which is possibly from a source up the Black hole.The X-ray source is locate above an accretion disc orbiting around the black hole,this assumption is invoked by recent studies about iron kα. we compute and arguing that due to the light bending effect near black hole, the flux striking the disk surface may be very concentrated,which will undoubtable change the disk's ionization state hence change the iron line's ionization state and emissivity.Also,Our model may explain the steep power law when modelling the lines. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0406/0406258v1.pdf"}
{"id": "astro-ph0406499", "abstract": "  We present very high resolution hydrodynamical simulations of accretion discs in black hole X-ray binaries accreting near the Eddington limit. The results show that mass loss, irradiation and tidal interactions all have a profound effect on the observed behaviour of long period X-ray transients. In particular, the interplay of all of these effects in the outer regions of the accretion disc is able to drive long time-scale (weeks to years) variability is these objects, and is a possible origin for some of the extreme variability of GRS1915+105. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0406/0406499v1.pdf"}
{"id": "astro-ph0408116", "abstract": "  We investigate a possible correlation between the orbital periods P of the extra-solar planet sample and the metallicity [Fe/H] of their parent stars. Close-in planets, on a few-days orbits, are more likely to be found around metal-rich stars. Simulations show that a weak correlation is present. This correlation becomes stronger when only sigle stars with one detected planet are considered. We discuss several potential sources of bias that might mimic the correlation, and find they can be ruled out, but not with high significance. If real, the absence of very short-period planets around the stellar sample with [Fe/H] < 0.0 can be interpreted as evidence of a metallicity dependence of the migration rates of giant planets during formation in the protoplanetary disc. The observed P-[Fe/H] correlation can be falsified or confirmed by conducting spectroscopic or astrometric surveys of metal-poor stars ([Fe/H] < -0.5) in the field. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0408/0408116v1.pdf"}
{"id": "astro-ph0408180", "abstract": "  Variations of radiocarbon concentration have been studied in annual rings for the last 350 years (1600-1950)on the basis of our experimental research using methods of spectral analysis. From this interval of time special attention is paid to the so-called period of the Maunder minimum (1645-1715) of solar activity. In the experimental series of corresponding period two types of periodicity are revealed: 20 year and 8 year. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0408/0408180v5.pdf"}
{"id": "astro-ph0408274", "abstract": "  We propose a method for determining the two-dimensional orbits of interstellar matter (ISM) in galactic disks using observed line-of-sight velocity fields. Although four components, consisting of two of position and two of velocity, are necessary to determine two-dimensional orbits, the velocity perpendicular to the line of sight can hardly be determined from observations. We show that the ISM orbits can be approximately determined by assuming that (1) the angular momentum is conserved along each orbit, (2) all orbits are closed in a single rotating frame, and (3) the system is symmetric through the origin. Since the angular momentum can be estimated on the major axis of a disk, a velocity perpendicular to the line of sight can be determined according to the conservation of angular momentum, and thus two components of velocity are obtained. The ISM orbits can be calculated by solving differential equations given by an obtained two-dimensional velocity field when a certain pattern speed is given. The typical deviation from the correct orbit is less than the observational resolution according to our test calculations for modeled velocity fields. We applied this method to the observed data of NGC 4569 and obtained possible orbits for this galaxy. Furthermore, we calculated the mass distribution using our result. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0408/0408274v2.pdf"}
{"id": "astro-ph0408357", "abstract": "  In a search for cataclysmic variables in the Calan-Tololo Survey we have detected 21 systems, 16 of them previously unknown. In this paper we present detailed time-series photometry for those six confirmed cataclysmic variables that show periodic variability in their light curves. Four of them turned out to be eclipsing systems, while the remaining two show a modulation consisting of two humps. All derived periods are below, or, in one case, just at the lower edge of the period gap. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0408/0408357v1.pdf"}
{"id": "astro-ph0409103", "abstract": "  We present preliminary results from an ongoing study of the bulges of S0 galaxies. We show that in a subsample of 14 barred S0 galaxies, fully half the photometrically defined bulges show kinematic signatures of \"pseudobulges\" – that is, their kinematics are dominated by rotation. In four of these galaxies, we identify at least two subcomponents in the photometric bulge region: flatter, disk or bar components, assocated with disklike kinematics; and rounder \"inner bulges,” which appear to be hotter systems more like classical bulges. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0409/0409103v1.pdf"}
{"id": "astro-ph0410397", "abstract": "  The central engine that drives gamma ray burst (GRB) explosions may derive from the ability of electrons/positrons and nucleons to tap into the momentum and energy from the large neutrino luminosity emitted by an accretion disk surrounding a black hole. This transfer of momentum and energy occurs due to neutrino absorption, scattering, and annihilation and the non-spherical geometry of the source both increases the annihilation efficiency and, close to the black hole, directs the momentum transfer towards the disk axis. We present annihilation efficiencies and the momentum/energy transfers for a number of accretion disk models and compute the critical densities of infalling material below which the transfer of neutrino momentum/energy will lead to an explosion. Models in which the neutrinos and antineutrinos become trapped within the disk have noticeably different momentum and energy deposition structure compared to thin disk models that may lead to significant differences in the explosion dynamics. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0410/0410397v1.pdf"}
{"id": "astro-ph0410554", "abstract": "  We present observations of CLASS B2108+213, the widest separation gravitational lens system discovered by the Cosmic Lens All-Sky Survey. Radio imaging using the VLA at 8.46 GHz and MERLIN at 5 GHz shows two compact components separated by 4.56 arcsec with a faint third component in between which we believe is emission from a lensing galaxy. 5-GHz VLBA observations reveal milliarcsecond-scale structure in the two lensed images that is consistent with gravitational lensing. Optical emission from the two lensed images and two lensing galaxies within the Einstein radius is detected in Hubble Space Telescope imaging. Furthermore, an optical gravitational arc, associated with the strongest lensed component, has been detected. Surrounding the system are a number of faint galaxies which may help explain the wide image separation. A plausible mass distribution model for CLASS B2108+213 is also presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0410/0410554v1.pdf"}
{"id": "astro-ph0410563", "abstract": "  A new method for absolute polarimetric calibration of large telescopes is presented. The proposed method is highly accurate and is based on the calibration of a small sub-aperture, which is then extended to the full system by means of actual observations of an astronomical source. The calibration procedure is described in detail along with numerical simulations that explore its robustness and accuracy. The advantages and disadvantages of this technique with respect to other possible alternatives are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0410/0410563v1.pdf"}
{"id": "astro-ph0410656", "abstract": "  We analyse oscillations observed in the X-ray light curve of the late-type star AT Mic. The oscillations occurred during flare maximum. We interpret these oscillations as density perturbations in the flare loop. Applying various models derived for the Sun, the loop length and the magnetic field of the flare can be estimated. We find a period of 740 s, and that the models give similar results (within a factor of 2) for the loop length ( 5.4e10 cm) and the magnetic field ( 100 G). For the first time, an oscillation of a stellar X-ray flare has been observed and results thus obtained for otherwise unobservable physical parameters. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0410/0410656v1.pdf"}
{"id": "astro-ph0410690", "abstract": "  We discuss the possibility to detect O/Ne white dwarfs by evidence for Ne overabundances. The hottest known WD, H1504+65, could be the only single WD for which we might be able to proof its O/Ne nature directly. Apart from this, strong Ne abundances are known or suspected only from binary systems, namely from a few novae, and from a handful of LMXBs. We try to verify the hypothesis that the latter might host strongly ablated O/Ne WD donors, by abundance analyses of the accretion disks in these systems. In any case, to conclude on O/Ne WDs just by strong Ne overabundances is problematic, because Ne enrichment also occurs by settling of this species into the core of C/O WDs. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0410/0410690v1.pdf"}
{"id": "astro-ph0411380", "abstract": "  The high spectral resolution and sensitivity of FUSE have enabled far-ultraviolet studies of AGN and QSOs that are a natural complement to observations using HST, Chandra, and XMM-Newton. Through synergistic use of the large sample of nearby AGN that serve as background probes of gas in the Galactic halo and the ISM, the FUSE PI team has observed a large number (approaching 100) of the nearest and brightest AGN. In addition to emission from O VI, we identify emission lines due to C III, N III, S IV, and He II in many of the Type-1 AGN. More than half of the Type 1 objects also show intrinsic absorption by the O VI doublet as well as C IV absorption and evidence of a soft X-ray warm absorber. Guest investigators have successfully coordinated FUSE observations of bright AGN with simultaneous HST and X-ray observations. These have contributed greatly to our understanding of the UV and X-ray absoring gas in AGN as either a wind from the accretion disk, or a thermally driven wind from the obscuring torus. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0411/0411380v1.pdf"}
{"id": "astro-ph0501157", "abstract": "  Studying simultaneous optical and X-ray light curves of radio-quiet AGN can help to probe the relationship between very different physical components - the cool, optically thick disk and hot, optically thin corona. Here, we review the relationship between optical and X-ray variability in Seyfert galaxies, which due to observing constraints was difficult to study for many years, but was given a huge boost with the launch of the RXTE satellite in 1995. We summarise the diverse results of several monitoring campaigns, which pose a challenge for standard theories relating optical and X-ray variability, with sources showing either correlated optical and X-ray flux variations, correlated optical flux and X-ray spectral variations, or no correlation at all. We discuss possible explanations for these results, some of which may be explained using a more standard AGN picture, while others may require additional components, such as the 2-phase accretion flows suggested to explain black hole X-ray binary behaviour. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0501/0501157v1.pdf"}
{"id": "astro-ph0502053", "abstract": "  As the shock and expanding shell of a supernova plow out through the circumstellar material at thousands of km/s, radio emission is generated. VLBI observations of this radio emission are presently the only means to directly image the expanding shell of any supernova much farther away than SN 1987A. The last decade has seen great progress in VLBI imaging of radio supernovae. In particular, SN 1993J in the galaxy M81 provided a rare opportunity to closely study an expanding supernova, and has been intensively observed. I summarize some of the results on SN 1993J and other radio supernovae, and compare the different observed radio supernovae. I briefly discuss the future prospects of radio supernovae imaging. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0502/0502053v2.pdf"}
{"id": "astro-ph0502164", "abstract": "  We propose the Particle Swarm Optimization (PSO) as an alternative method for locating periodic orbits in a three–dimensional (3D) model of barred galaxies. We develop an appropriate scheme that transforms the problem of finding periodic orbits into the problem of detecting global minimizers of a function, which is defined on the Poincaré Surface of Section (PSS) of the Hamiltonian system. By combining the PSO method with deflection techniques, we succeeded in tracing systematically several periodic orbits of the system. The method succeeded in tracing the initial conditions of periodic orbits in cases where Newton iterative techniques had difficulties. In particular, we found families of 2D and 3D periodic orbits associated with the inner 8:1 to 12:1 resonances, between the radial 4:1 and corotation resonances of our 3D Ferrers bar model. The main advantages of the proposed algorithm is its simplicity, its ability to work using function values solely, as well as its ability to locate many periodic orbits per run at a given Jacobian constant. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0502/0502164v1.pdf"}
{"id": "astro-ph0503332", "abstract": "  Gamma ray bursts are among the most energetic events in the known universe. A highly relativistic fireball is ejected. In most cases the burst itself is followed by an afterglow, emitted under deceleration as the fireball plunges through the circum-stellar media. To interpret the observations of the afterglow emission, two physical aspects need to be understood: 1) The origin and nature of the magnetic field in the fireball and 2) the particle velocity distribution function behind the shock. Both are necessary in existing afterglow models to account for what is believed to be synchrotron radiation. To answer these questions, we need to understand the microphysics at play in collisionless shocks. Using 3D particle-in-cell simulations we can gain insight in the microphysical processes that take place in such shocks. We discuss the results of such computer experiments. It is shown how a Weibel-like two-stream plasma instability is able to create a strong transverse intermittent magnetic field and points to a connected mechanism for in situ particle acceleration in the shock region. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0503/0503332v1.pdf"}
{"id": "astro-ph0503509", "abstract": "  We determine the spatial distribution function of galaxies from a wide range of samples in the 2MASS survey. The results agree very well with the form of the distribution predicted by the theory of cosmological gravitational many-body galaxy clustering. On large scales we find a value of the clustering parameter b = 0.867 +/- 0.026, in agreement with b = 0.83 +/- 0.05 found previously for the Pisces-Perseus supercluster. We measure b(theta) as a function of scale, since this is a powerful test of the applicability of computer simulations. The results suggest that when galaxies clustered they were usually surrounded by individual, rather than by communal haloes. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0503/0503509v1.pdf"}
{"id": "astro-ph0504335", "abstract": "  Near-infrared images have been used to search for bright globular clusters near the center of the elliptical galaxy Maffei 1. The number of objects in various radial intervals from the center of Maffei 1 are compared with the number density of sources in two control fields, and we find an excess of 31 +/- 11 objects with K between 16.6 and 18.0 in an annulus between 20 and 90 arcsec from the galaxy center. At radii in excess of 90 arcsec the ability to find clusters is frustrated by statistical noise in the foreground star population. It is demonstrated that the globular clusters located within 90 arcsec of the center of Maffei 1 span a range of near-infrared colors that are at least as great as that which is seen among M31 clusters; some of the clusters appear to have colors that are consistent with them being very young. The specific globular cluster frequency within 90 arcsec of the center of Maffei 1 is S_N = 1.3 +/- 0.6 if the distance modulus is 28.1 +/- 0.2 and A_V = 4.7 +/- 0.2. The specific cluster frequency of Maffei 1 is thus similar to that of other nearby field elliptical galaxies. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0504/0504335v1.pdf"}
{"id": "astro-ph0506505", "abstract": "  We report the first detection of new dust formation in an SC star. The prototype of the SC stars, UY Cen, underwent a decline of 2 magnitudes in the V-band. The SC stars show pulsational variations and have 60 micron excesses indicating past dust formation. It has been suggested that as a star evolves from oxygen rich to carbon rich, there is a short period of time when C/O1 that the star appears spectroscopically as an SC star and ceases to produce dust. The SC star, BH Cru, has shown large spectroscopic and pulsation period variations in only 30 years, indicating rapid evolution but it has shown no sign of new dust formation. UY Cen has not shown any pulsation or spectroscopic variations accompanying the onset of its dust formation. In addition, UY Cen did not show emission in the resonance lines of Na I, K I or Rb I when it was at its faintest, although these lines were a feature of the carbon stars R Lep and V Hya during similar faint phases.", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0506/0506505v1.pdf"}
{"id": "astro-ph0506536", "abstract": "  We present near-infrared J, H, and K_s images and K-band spectroscopy of two newly discovered stellar clusters at different stages of evolution. Our spectra suggest the presence of massive YSOs in the heavily embedded cluster in the star-forming region near radio source G353.4-0.4 and an O5-O6V star in the cluster near radio source G305+00.2. We determine a K-band luminosity function (KLF) for both clusters and an initial mass function (IMF) for the cluster near G305+00.2. The derived IMF slope is -1.5 if the KLF is used to derive the IMF and is -0.98 if the color-magnitude diagram and spectra are used. The more reliable CMD-based slope is flatter than the Salpeter value usually found for stellar clusters. We find that using the KLF alone to derive an IMF is likely to produce an overly steep slope in stellar clusters subject to variable extinction. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0506/0506536v1.pdf"}
{"id": "astro-ph0506709", "abstract": "  NGC 6397 is the closest globular cluster, and hence the ideal place to search for faint stellar populations such as cataclysmic variables (CVs). HST and Chandra observers have identified nine certain and likely CVs in this nearby cluster, including several magnetic CV candidates. We have combined our recent UV imagery with archival HST images of NGC 6397 to search for new CV candidates and especially to look for dwarf nova-like eruptive events. We find remarkable and somewhat unexpected dwarf nova-like eruptions of the two well-known cataclysmic systems CV2 and CV3. These two objects have been claimed to be magnetic CVs, as indicated by their helium emission-line spectra. Magnetic fields in CVs are usually expected to prevent the disk instability that leads to dwarf nova eruptions. In fact, most field magnetic CVs are observed to not undergo eruptions. Our observations of the dwarf nova eruptions of CV2 and CV3 can be reconciled with these objects' HeII emission lines if both objects are infrequently-erupting intermediate polars, similar to EX Hya. If this is the case for most globular cluster CVs then we can reconcile the many X-ray and UV bright CV candidates seen by Chandra and HST with the very small numbers of erupting dwarf novae observed in cluster cores. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0506/0506709v2.pdf"}
{"id": "astro-ph0506760", "abstract": "  We report preliminary results from our near-infrared JHK survey of star clusters in the LMC. The primary goals of the survey are to study the three-dimensional structure and distance of the LMC. In 2003 and 2004 we used the Infrared Side Port Imager (ISPI) on the CTIO 4m to obtain near infrared photometry for a sample of populous LMC clusters. We utilize the K-band luminosity of core helium burning red clump (RC) stars to obtain individual cluster distances and present a preliminary assessment of the structure and geometry of the LMC based on a subset of our data. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0506/0506760v1.pdf"}
{"id": "astro-ph0508542", "abstract": "  The reconstruction of scalar-field dark energy models is studied for a general Lagrangian density p(ϕ, X), where X is a kinematic term of a scalar field ϕ. We implement the coupling Q between dark energy and dark matter and express reconstruction equations using two observables: the Hubble parameter H and the matter density perturbation δ_m. This allows us to determine the structure of corresponding theoretical Lagrangian together with the coupling Q from observations. We apply our formula to several forms of Lagrangian and present concrete examples of reconstruction by using the recent Gold dataset of supernovae measurements. This analysis includes a generalized ghost condensate model as a way to cross a cosmological-constant boundary even for a single-field case. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0508/0508542v2.pdf"}
{"id": "astro-ph0510066", "abstract": "  We report “infall asymmetry” in the HCO^+ (1–0) and (3–2) lines toward NGC 1333, extended over ∼ 0.39  pc^2, a larger extent than has been reported be fore, for any star-forming region. The infall asymmetry extends over a major portion of the star-forming complex, and is not limited to a single protostar, or to a single dense core, or to a single spectral line. It seems likely that the infall asymmetry represents inward motions, and that these motions are physically associated with the complex. Both blue-asymmetric and red-asymmetric lines are seen, but in both the (3–2) and (1–0) lines of HCO^+ the vast majority of the asymmetric lines are blue, indicating inward motions. The (3–2) line, tracing denser gas, has the spectra with the strongest asymmetry and these spectra are associated with the protostars IRAS 4A and 4B, which most likely indicates a warm central source is affecting the line profiles. The (3–2) and (1–0) lines usually have the same sense of asymmetry in common positions, but their profiles differ significantly, and the (1–0) line appears to trace motions on much larger spatial scales than does the (3–2) line. Line profile models fit the spectra well, but do not strongly constrain their parameters. The mass accretion rate of the inward motions is of order 10^-4 M_⊙/yr, similar to the ratio of stellar mass to cluster age. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0510/0510066v1.pdf"}
{"id": "astro-ph0510130", "abstract": "  We have analyzed a homogeneous set of observations of eighty-one transneptunian objects obtained with the NIC2 camera on the Hubble Space Telescope with the goal of identifying partially resolved binaries. Using PSF-fitting we have identified six likely binaries in addition to the three new binaries already found in this data set. We find that 11", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0510/0510130v1.pdf"}
{"id": "astro-ph0510271", "abstract": "  The observed enhancement of the Fe Kα line in three gravitationally lensed QSOs (MG J0414+0534, QSO 2237+0305, H1413+117) is interpreted in terms of microlensing, even when equivalent X-ray continuum amplification is not observed. In order to interpret these observations, first we studied the effects of microlensing on quasars spectra, produced by straight fold caustic crossing over standard relativistic accretion disk. The disk emission was analyzed using the ray tracing method, considering Schwarzschild and Kerr metrics. When the emission is separated in two regions (an inner disk corresponding to the Fe Kα line and an outer annulus corresponding to the continuum, or vice-versa) we find microlensing events which enhance the Fe Kα line without noticeable amplification of the X-ray continuum, but only during a limited time interval. Continuum amplification is expected if a complete microlensing event is monitored. Second, we studied a more realistic case of amplification by caustic magnification pattern. In this case we could satisfactorily explain the observations if the Fe Kα line is emitted from the innermost part of the accretion disk, while the continuum is emitted from a larger region. Also, we studied the chromatic effects of microlensing, finding that the radial distribution of temperature in the accretion disk, combined with microlensing itself, can induce wavelength dependent variability of ∼ 30", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0510/0510271v1.pdf"}
{"id": "astro-ph0510344", "abstract": "  We present an overview of pulsating stars in close binaries, focusing on the question what role the dupliticity plays in triggering and/or modifying stellar oscillations and on how it can help us to interpret the oscillatory behaviour of (one of) the components. We give examples of characteristic types of oscillations observed in binaries: forced oscillations and free oscillations in both, short- and long-period binaries. The importance of studies of oscillations in eclipsing binaries is also pointed out. A list of line-profile and rapid light variables in close binaries with their basic properties is provided. No obvious relations among the orbital eccentricity, orbital frequency, rotational frequency and intrinsic frequencies of oscillations were found. The value and future prospects of asteroseismic studies of binary stars are briefly outlined while the complexity of the problem and its possible complications are also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0510/0510344v1.pdf"}
{"id": "astro-ph0510546", "abstract": "  Weak gravitational lensing has become an important tool to study the properties of dark matter halos around galaxies, thanks to the advent of large panoramic cameras on 4m class telescopes. This area of research has been developing rapidly in the past few years, and in these proceedings we present some results based on the Red-Sequence Cluster Survey, thus highlighting what can be achieved with current data sets. We present results on the measurement of virial masses as a function of luminosity and the extent of dark matter halos. Much larger surveys are underway or planned, which will result in an impressive improvement in the accuracy of the measurements. However, the interpretation of future results will rely more and more on comparison with numerical simulations, thus providing direct tests of galaxy formation models. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0510/0510546v1.pdf"}
{"id": "astro-ph0510588", "abstract": "  We have performed the first polarimetry of solar flare emission at gamma-ray energies (0.2-1 MeV). These observations were performed with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) for two large flares: the GOES X4.8-class solar flare of 2002 July 23, and the X17-class flare of 2003 October 28. We have marginal polarization detections in both flares, at levels of 21", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0510/0510588v1.pdf"}
{"id": "astro-ph0511043", "abstract": "  Recent breakthroughs in cosmology reveal that a quarter of the Universe is composed of dark matter, but the microscopic identity of dark matter remains a deep mystery. I review recent progress in resolving this puzzle, focusing on two well-motivated classes of dark matter candidates: WIMPs and superWIMPs. These possibilities have similar motivations: they exist in the same well-motivated particle physics models, the observed dark matter relic density emerges naturally, and dark matter particles have mass around 100 GeV, the energy scale identified as interesting over 70 years ago by Fermi. At the same time, they have widely varying implications for direct and indirect dark matter searches, particle colliders, Big Bang nucleosynthesis, the cosmic microwave background, and halo profiles and structure formation. If WIMPs or superWIMPs are a significant component of dark matter, we will soon be entering a golden era in which dark matter will be studied through diverse probes at the interface of particle physics, astroparticle physics, and cosmology. I outline a program of dark matter studies for each of these scenarios, and discuss the prospects for identifying dark matter in the coming years. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0511/0511043v1.pdf"}
{"id": "astro-ph0511395", "abstract": "  Further achievements of the XMM-Newton cross-calibration - XMM internal as well as with other X-ray missions - are presented. We explain the major changes in the new version SASv6.5 of the XMM-Newton science analysis system. The current status of the cross-calibration of the three EPIC cameras is shown. Using a large sample of blazars, the pn energy redistribution at low energy could be further calibrated, correcting the overestimation of fluxes in the lowest energy regime. In the central CCDs of the MOSs, patches were identified at the bore-sight positions, leading to an underestimation of the low energy fluxes. The further improvement in the understanding of the cameras resulted in a good agreement of the EPIC instruments down to lowest energies. The latest release of the SAS software package already includes corrections for both effects as shown in several examples of different types of sources. Finally the XMM internal cross-calibration is completed by the presentation of the current cross-calibration status between EPIC and RGS instruments. Major efforts have been made in cross-calibrations with other X-ray missions, most importantly with Chandra, of course, but also with currently observing satellites like Swift. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0511/0511395v1.pdf"}
{"id": "astro-ph0512606", "abstract": "  A revision of Stodolkiewicz's Monte Carlo code is used to simulate the evolution of million body star clusters. The new method treats each superstar as a single star and follows the evolution and motion of all individual stellar objects. A survey of the evolution of N-body systems influenced by the tidal field of a parent galaxy and by stellar evolution is presented. The process of energy generation is realized by means of appropriately modified versions of Spitzer's and Mikkola's formulae for the interaction cross section between binaries and field stars and binaries themselves. The results presented are in good agreement with theoretical expectations and the results of other methods. During the evolution, the initial mass function (IMF) changes significantly. The local mass function (LMF) around the half–mass radius closely resembles the actual global mass function (GMF). At the late stages of evolution the mass of the evolved stars inside the core can be as high as 97", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0512/0512606v1.pdf"}
{"id": "astro-ph0601379", "abstract": "  Accretion flows with pressure gradients permit the existence of standing waves which may be responsible for observed quasi-periodic oscillations (QPO's) in X-ray binaries. We present a comprehensive treatment of the linear modes of a hydrodynamic, non-self-gravitating, polytropic slender torus, with arbitrary specific angular momentum distribution, orbiting in an arbitrary axisymmetric spacetime with reflection symmetry. We discuss the physical nature of the modes, present general analytic expressions and illustrations for those which are low order, and show that they can be excited in numerical simulations of relativistic tori. The mode oscillation spectrum simplifies dramatically for near Keplerian angular momentum distributions, which appear to be generic in global simulations of the magnetorotational instability. We discuss our results in light of observations of high frequency QPO's, and point out the existence of a new pair of modes which can be in an approximate 3:2 ratio for arbitrary black hole spins and angular momentum distributions, provided the torus is radiation pressure dominated. This mode pair consists of the axisymmetric vertical epicyclic mode and the lowest order axisymmetric breathing mode. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0601/0601379v1.pdf"}
{"id": "astro-ph0601413", "abstract": "  We present measurements obtained with the Spitzer Space Telescope in five bands from 3.6-24 microns of the northern inner radio lobe of Centaurus A, the nearest powerful radio galaxy. We show that this emission is synchrotron in origin. Comparison with ultraviolet observations from GALEX shows that diffuse ultraviolet emission exists in a smaller region than the infrared but also coincides with the radio jet. We discuss the possibility, that synchrotron emission is responsible for the ultraviolet emission and conclude that further data are required to confirm this. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0601/0601413v2.pdf"}
{"id": "astro-ph0602105", "abstract": "  We have measured the angular diameters of six M dwarfs with the CHARA Array, a long-baseline optical interferometer located at Mount Wilson Observatory. Spectral types range from M1.0 V to M3.0 V and linear radii from 0.38 to 0.69 Rsun. These results are consistent with the seven other M-dwarf radii measurements from optical interferometry and with those for sixteen stars in eclipsing binary systems. We compare all directly measured M dwarf radii to model predictions and find that current models underestimate the true stellar radii by up to 15-20", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0602/0602105v1.pdf"}
{"id": "astro-ph0602164", "abstract": "  The effects of classical gravitational radiation in models with large extra dimensions are investigated for ultra high energy cosmic rays (CRs). The cross sections are implemented into a simulation package (SENECA) for high energy hadron induced CR air showers. We predict that gravitational radiation from quasi-elastic scattering could be observed at incident CR energies above 10^9 GeV for a setting with more than two extra dimensions. It is further shown that this gravitational energy loss can alter the energy reconstruction for CR energies E_ CR≥ 5· 10^9 GeV. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0602/0602164v1.pdf"}
{"id": "astro-ph0602247", "abstract": "  We present a study of the turbulent velocity fields in the Intra Cluster Medium of a sample of 21 galaxy clusters simulated by the SPH–code Gadget2, using a new numerical scheme where the artificial viscosity is suppressed outside shocks. The turbulent motions in the ICM of our simulated clusters are detected with a novel method devised to better disentangle laminar bulk motions from chaotic ones. We focus on the scaling law between the turbulent energy content of the gas particles and the total mass, and find that the energy in the form of turbulence scales approximatively with the thermal energy of clusters. We follow the evolution with time of the scaling laws and discuss the physical origin of the observed trends. The simulated data are in agreement with independent semi–analytical calculations, and the combination between the two methods allows to constrain the scaling law over more than two decades in cluster mass. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0602/0602247v2.pdf"}
{"id": "astro-ph0603066", "abstract": "  The past few years have seen a steady progress in the determination of element abundances at high redshifts, with new and more accurate measures of metallicities in star-forming galaxies, in QSO absorbers, and in the intergalactic medium. We have also become more aware of the limitations of the tools at our disposal in such endeavours. I summarise these recent developments and–in tune with the theme of this meeting–consider the clues which chemical abundance studies offer to the links between the high redshift galaxy populations and today's galaxies. The new data are `fleshing out' the overall picture of element abundances at redshifts z = 2 - 3 which has been gradually coming into focus over the last decade. In particular, we can now account for at least 40", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0603/0603066v1.pdf"}
{"id": "astro-ph0603552", "abstract": "  The distribution of secondary star masses in present-day post-common envelope binaries (PCEBs) is calculated using four different models for angular momentum loss (AML) during the post-CE phase: only gravitational radiation (GR), GR + disrupted magnetic braking (DMB), GR + reduced MB, and GR + intermediate MB. For the DMB model, we find that the number of PCEBs decreases abruptly by 38", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0603/0603552v1.pdf"}
{"id": "astro-ph0605332", "abstract": "  We present the exact analytic expressions to compute, assuming the emitted Gamma-Ray Burst (GRB) radiation is not spherically symmetric but is confined into a narrow jet, the value of the detector arrival time at which we start to \"see\" the sides of the jet, both in the fully radiative and adiabatic regimes. We obtain this result using our exact analytic expressions for the EQuiTemporal Surfaces (EQTSs) in GRB afterglows. We re-examine the validity of three different approximate formulas currently adopted for the adiabatic regime in the GRB literature. We also present an empirical fit of the numerical solutions of the exact equations, compared and contrasted with the three above approximate formulas. The extent of the differences is such as to require a reassessment on the existence and entity of beaming in the cases considered in the current literature, as well as on its consequences on the GRB energetics. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0605/0605332v1.pdf"}
{"id": "astro-ph0606471", "abstract": "  Medium-resolution optical spectroscopy of the candidate YSOs associated with the small, nearby molecular cloud Lynds 1333 revealed four previously unknown classical T Tauri stars, two of which are components of a visual double, and a Class I source, IRAS 02086+7600. The spectroscopic data, together with new V,R_ C,I_C photometric and 2MASS J, H, and K_s data allowed us to estimate the masses and ages of the new T Tauri stars. We touch on the possible scenario of star formation in the region. L1333 is one of the smallest and nearest known star forming clouds, therefore it may be a suitable target for studying in detail the small scale structure of a star forming environment. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0606/0606471v1.pdf"}
{"id": "astro-ph0606731", "abstract": "  We discuss certain issues related to the limitations of density parameters for a “radiation”-like contribution to the Friedmann equation using kinematical or geometrical measurements. We analyse the observational constraint of a negative (1+z)^4-type contribution in cosmological models. We argue that it is not possible to determine the energy densities of individual components of matter scaling like radiation from astronomical observations. We find three different interpretations of the presence of the radiation term: 1) the FRW universe filled with a massless scalar field in a quantum regime (the Casimir effect), 2) the Friedmann-Robertson-Walker (FRW) model in the Randall Sundrum scenario with dark radiation, 3) the cosmological model with global rotation. From supernovae type Ia (SNIa) data, Fanaroff-Riley type IIb (FRIIb) radio galaxy (RG) data, baryon oscillation peak and cosmic microwave background radiation (CMBR) observations we obtain bounds for the negative radiation-like term. A small negative contribution of dark radiation can reconcile the tension in nucleosynthesis and remove also the disagreement between H_0 values obtained from both SNIa and the Wilkinson Microwave Anisotropy Probe (WMAP) satellite data. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0606/0606731v3.pdf"}
{"id": "astro-ph0606737", "abstract": "  We study the scattering of low-energy Cosmic Rays (CRs) in a turbulent, compressive MHD fluid. We show that compressible MHD modes – fast or slow waves with wave lengths smaller than CR mean free paths induce cyclotron instability in CRs. The instability feeds the new small-scale Alfvenic wave component with wave vectors mostly along magnetic field, which is not a part of the MHD turbulence cascade. This new component gives feedback on the instability through decreasing the CR mean free path. We show that the ambient turbulence fully suppresses the instability at large scales, while wave steepening constrains the amplitude of the waves at small scales. We provide the energy spectrum of the plane-parallel Alfvenic component and calculate mean free paths of CRs as a function of their energy. We find that for the typical parameters of turbulence in the interstellar medium and in the intercluster medium the new Alfvenic component provides the scattering of the low energy CRs that exceeds the direct resonance scattering by MHD modes. This solves the problem of insufficient scattering of low-energy CRs in the turbulent interstellar or intracluster medium that was reported in the literature. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0606/0606737v2.pdf"}
{"id": "astro-ph0608277", "abstract": "  We present the constraints on inflationary parameters in a flat ΛCDM universe obtained by WMAP three year data release, plus smaller scale CMB and two LSS data sets, 2dF and SDSS (treated separately). We use a Markov Chain Monte Carlo (MCMC) technique combined with an analytic description of the inflationary spectra in terms of the horizon flow functions (HFF). By imposing a consistency condition for the tensor-to-scalar ratio, we study the constraints both on single field standard inflation and on inflation with the violation of the null energy condition, which leads to a blue spectrum for gravitational waves. For standard inflation, the constraint on the tensor-to-scalar ratio we obtain from CMB data and 2dF05 is: r_0.01 < 0.26 at 2 σ cl. Without the consistency condition between the tensor-to-scalar ratio and the tensor slope, the constraints on the tensor amplitude is not significantly changed, but the constraints on the HFFs are significantly relaxed. We then show that when the third HFF ϵ_3 is allowed to be non-zero and to be of order unity, a large negative (at 2 σ) value for the running of the scalar spectral index in standard inflation is found in any set of data we consider. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0608/0608277v2.pdf"}
{"id": "astro-ph0609315", "abstract": "  Regionally averaged relativistic cosmologies have recently been considered as a possible explanation for the apparent late time acceleration of the Universe. This contribution reports on a mean field description of the backreaction in terms of a minimally coupled regionally homogeneous scalar field evolving in a potential, then giving a physical origin to the various phenomenological scalar fields generically called quintessence fields. As an example, the correspondence is then applied to scaling solutions. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0609/0609315v2.pdf"}
{"id": "astro-ph0610032", "abstract": "  It is believed that the observed diffuse gamma ray emission from the galactic plane is the result of interactions between cosmic rays and the interstellar gas. Such emission can be amplified if cosmic rays penetrate into dense molecular clouds. The propagation of cosmic rays inside a molecular cloud has been studied assuming an arbitrary energy and space dependent diffusion coefficient. If the diffusion coefficient inside the cloud is significantly smaller compared to the average one derived for the galactic disk, the observed gamma ray spectrum appears harder than the cosmic ray spectrum, mainly due to the slower penetration of the low energy particles towards the core of the cloud. This may produce a great variety of gamma ray spectra. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0610/0610032v1.pdf"}
{"id": "astro-ph0610231", "abstract": "  Recent Chandra observations of an outflowing gas in GRO J1655-40 resulted in a suggestion by Miller et al. (2006) that the wind in this system must be powered by a magnetic process that can also drive accretion through the disk around the black hole. The alternative explanations, of radiation pressure or thermally driven flows, were considered unsatisfactory because of the highly ionized level of the gas and because of the derived small distance from the black hole, well inside the minimum distance required for an efficient X-ray heated wind. The present paper shows that there is a simple photoionized wind solution for this system where the gas is much further out than assumed by Miller et al., at r/r_g = 10^(4.7-5.7). The expected wind velocity, as well as the computed equivalent widths of more than 50 absorption lines in this single-component 1D model, are all in good agreement with the Chandra observations. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0610/0610231v1.pdf"}
{"id": "astro-ph0610960", "abstract": "  The Gamma-ray Large Area Space Telescope (GLAST) is a space-based observatory scheduled to launch in October 2007 with two instruments: (1) the GLAST Burst Monitor (GBM), sensitive to photon energies between 8 keV and 25 MeV and optimized to detect gamma-ray bursts, and (2) the Large Area Telescope (LAT), sensitive to gamma rays between  20 MeV and 300 GeV and designed to survey the gamma-ray sky with unprecedented sensitivity. We describe the LAT and the GBM. We then focus on the LAT's capabilities for studying active galactic nuclei. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0610/0610960v1.pdf"}
{"id": "astro-ph0611003", "abstract": "  We analyze the mixed frame equations of radiation hydrodynamics under the approximations of flux-limited diffusion and a thermal radiation field, and derive the minimal set of evolution equations that includes all terms that are of leading order in any regime of non-relativistic radiation hydrodynamics. Our equations are accurate to first order in v/c in the static diffusion regime. In contrast, we show that previous lower order derivations of these equations omit leading terms in at least some regimes. In comparison to comoving frame formulations of radiation hydrodynamics, our equations have the advantage that they manifestly conserve total energy, making them very well-suited to numerical simulations, particularly with adaptive meshes. For systems in the static diffusion regime, our analysis also suggests an algorithm that is both simpler and faster than earlier comoving frame methods. We implement this algorithm in the Orion adaptive mesh refinement code, and show that it performs well in a range of test problems. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0611/0611003v2.pdf"}
{"id": "astro-ph0611566", "abstract": "  We present our activity on making the Subaru Data Archive accessible through the Japanese Virtual Observatory (JVO) system. There are a lot of demand to use the archived Subaru data from various fields of astronomers. To be used by those who are not familiar with the way to reduce the Subaru data, the data reduction should be made before providing for them, or at least it should be easily done without precise knowledge about instrument's characteristic and environment where data are taken. For those purposes, data quality assessment system NAQATA is developed, which is presented in this meeting by Nakata et al. (2006), and the science-ready image data are provided for some of the SuprimeCam data at SMOKA data service which is presented by Enoki et al (2006). JVO portal will provide the way to access the reduce data, and also provides the way to reduce from raw data with very few efforts through the user-friendly web browser I/F. To provide such a CPU-intensive service, we have developed a GRID computing system. The architecture of this Subaru Data and Analysis system are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0611/0611566v1.pdf"}
{"id": "astro-ph0611811", "abstract": "  Previous models of dust growth in protoplanetary disks considered either uniformly laminar or turbulent disks. This Letter explores how dust growth occurs in a layered protoplanetary disk in which the magnetorotational instability generates turbulence only in the surface layers of a disk. Two cases are considered: a completely laminar dead zone and a dead zone in which turbulence is “stirred up” from the MRI acting above. It is found that dust is depleted from high altitudes in layered disks faster than in those cases of a uniformly laminar or turblent disks. This is a result of the accelerated growth of particles in the turbulent regions and their storage in the lower levels where they escape energetic collisions which would result in disruption. Thus the regions of a protoplanetary disk above a dead zone would become rapidly depleted in small dust grains, whereas the outer regions, where the MRI is active throughout, will maintain a small dust poplulation at all heights due to the disruptive collisions and vertical mixing from turbulence. This structure is similar to that which has been inferred for disks around TW Hydra, GM Auriga, and CoKu Tau/4, which are depleted in dust close to the star, but are optically thick at larger heliocentric distances. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0611/0611811v1.pdf"}
{"id": "astro-ph0612263", "abstract": "  The Draco dwarf spheroidal galaxy (dSph), with its apparent immense mass to light ratio and compact size, holds many clues to the nature of the enigmatic dark matter. Here we present deep photometric studies of this dwarf galaxy, undertaken with the MegaCam Camera at the Canada-France-hawaii Telescope, the Wide Field Camera at the Isaac Newton Telescope and the Wide-Field and Planetary Camera on board the Hubble Space Telescope. The new photometric data cover the entirety of the galaxy, and reach i=24.5 at 50", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0612/0612263v1.pdf"}
{"id": "astro-ph0612316", "abstract": "  The concept of Galactic Habitable Zone (GHZ) was introduced a few years ago as an extension of the much older concept of Circumstellar Habitable Zone. However, the physical processes underlying the former concept are hard to identify and even harder to quantify. That difficulty does not allow us, at present, to draw any significant conclusions about the extent of the GHZ: it may well be that the entire Milky Way disk is suitable for complex life. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0612/0612316v1.pdf"}
{"id": "astro-ph0612595", "abstract": "  We present X-ray and multi-frequency radio observations of the central radio sources in several X-ray cavity systems. We show that targeted radio observations are key to determining if the lobes are being actively fed by the central AGN. Low frequency observations provide a unique way to study both the lifecycle of the central radio source as well as its energy input into the ICM over several outburst episodes. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0612/0612595v1.pdf"}
{"id": "astro-ph0612678", "abstract": "  This paper reviews some of the most recent advances in the application of the Hanle effect to solar physics, and how these developments are allowing us to explore the magnetism of the photospheric regions that look “empty” in solar magnetograms–that is, the Sun's “hidden” magnetism. In particular, we show how a joint analysis of the Hanle effect in atomic and molecular lines indicates that there is a vast amount of hidden magnetic energy and unsigned magnetic flux localized in the (intergranular) downflowing regions of the quiet solar photosphere, carried mainly by tangled fields at sub-resolution scales with strengths between the equipartition field values and 1 kG. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0612/0612678v1.pdf"}
{"id": "astro-ph0701232", "abstract": "  We describe in this paper a new, public software for accurate \"PSF-matched\" multiband photometry for images of different resolution and depth, that we have named ConvPhot, of which we analyse performances and limitations. It is designed to work when a high resolution image is available to identify and extract the objects, and colours or variations in luminosity are to be measured in another image of lower resolution but comparable depth. To maximise the usability of this software, we explicitly use the outputs of the popular SExtractor code, that is used to extract all objects from the high resolution \"detection\" image. The technique adopted by the code is essentially to convolve each object to the PSF of the lower resolution \"measure\" image, and to obtain the flux of each object by a global chi2 minimisation on such \"measure\" image. We remark that no a priori assumption is done on the shape of the objects. In this paper we provide a full description of the algorithm, a discussion of the possible systematic effects involved and the results of a set of simulations and validation tests that we have performed on real as well as simulated images. The source code of ConvPhot, written in C language under the GNU Public License, is released worldwide. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0701/0701232v1.pdf"}
{"id": "astro-ph0701573", "abstract": "  A list of 50 optically observable O stars that are likely on or very near the ZAMS is presented. They have been selected on the basis of five distinct criteria, although some of them exhibit more than one. Three of the criteria are spectroscopic (He II λ4686 absorption stronger than in normal luminosity class V spectra, abnormally broad or strong Balmer lines, weak UV wind profiles for their spectral types), one is environmental (association with dense, dusty nebular knots), and one is photometric (derived absolute magnitudes fainter than class V). Very few of these stars have been physically analyzed, and they have not been considered in the current framework of early massive stellar evolution. In particular, they may indicate that the earliest, embedded phases are not as large a fraction of the main-sequence lifetimes as is currently believed. Detailed analyses of these objects will likely prove essential to a complete understanding of the early evolution of massive stars. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0701/0701573v2.pdf"}
{"id": "astro-ph0703161", "abstract": "  In this paper, we calculate simulated scattered light images of a circumstellar disk in which a planet is forming by gravitational instability. The simulated images bear no correlation to the vertically integrated surface density of the disk, but rather trace the density structure in the tenuous upper layers of the disk. Although the density at high altitudes does not bear a direct relation to activity at the midplane, the very existence of structure at high altitudes along with high time variability is an indicator of gravitational instability within the disk. The timescale for variations is much shorter than the orbital period of the planet, which facilitates observation of the phenomenon. Scattered light images may not necessarily be able to tell us where exactly a planet might be forming in a disk, but can still be a useful probe of active planet formation within a circumstellar disk. Although these phenomena are unlikely to be observable by current telescopes, future large telescopes, such as the Giant Magellan Telescope, may be able to detect them. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0703/0703161v1.pdf"}
{"id": "astro-ph0703257", "abstract": "  We analyse the implications of superfluid turbulence for neutron star physics. We begin by extending our previous results for the mutual friction force for a straight vortex array to account for the self-induced flow which arises when the vortices are curved. We then discuss Vinen's phenomenological model for isotropic turbulence, and derive the associated (Gorter-Mellink) form for the mutual friction. We compare this derivation to a more recent analysis of Schwarz, which sheds light on various involved issues. Having discussed isotropic turbulence, we argue that this case is unlikely to be relevant for neutron stars. Instead we expect a rotating neutron star to exhibit polarised turbulence, where relative flow drives the turbulence and rotation counteracts it. Based on recent results for superfluid Helium, we construct a phenomenological model that should have the key features of such a polarised turbulent system. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0703/0703257v1.pdf"}
{"id": "astro-ph0703442", "abstract": "  The ANTARES Neutrino Telescope is a water Cherenkov detector currently under construction in the Mediterranean Sea. It is also designed to serve as a platform for investigations of the deep-sea environment. In this context, the ANTARES group at the University of Erlangen will integrate acoustic sensors within the infrastructure of the experiment. With this dedicated setup, tests of acoustic particle detection methods and deep-sea acoustic background studies shall be performed. The aim of this project is to evaluate the feasibility of a future acoustic neutrino telescope in the deep sea operating in the ultra-high energy regime. In these proceedings, the implementation of the project is described in the context of the premises and challenges set by the physics of acoustic particle detection and the integration into an existing infrastructure. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0703/0703442v1.pdf"}
{"id": "astro-ph0703444", "abstract": "  The acoustic detection method is a promising option for future neutrino telescopes operating in the ultra-high energy regime. It utilises the effect that a cascade evolving from a neutrino interaction generates a sound wave, and is applicable in different target materials like water, ice and salt. Described here are the developments in and the plans for the research on acoustic particle detection in water performed by the ANTARES group at the University of Erlangen within the framework of the ANTARES experiment in the Mediterranean Sea. A set of acoustic sensors will be integrated into this optical neutrino telescope to test acoustic particle detection methods and perform background studies. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0703/0703444v1.pdf"}
{"id": "astro-ph9604031", "abstract": "  We show that the Einstein ring radius and transverse speed of a lens projected on the source plane, r̂_ e and v̂, can be determined from the light curve of a binary-source event, followed by the spectroscopic determination of the orbital elements of the source stars. The determination makes use of the same principle that allows one to measure the Einstein ring radii from finite-source effects. For the case when the orbital period of the source stars is much longer than the Einstein time scale, P≫ t_ e, there exists a single two-fold degeneracy in determining r̂_ e. However, when P ≲ t_ e the degeneracy can often be broken by making use of the binary-source system's orbital motion. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9604/9604031v2.pdf"}
{"id": "astro-ph9605056", "abstract": "  The two-point angular correlation function, , is constructed from a catalog of 13,000 objects in 24 fields distributed over an area of 4 deg^2 and complete to a limit of R = 23.5. The amplitude and slope of our correlation function on arcminute scales are in broad agreement with recent CCD results in the literature and decreases with depth. No evidence is found for a flattening of the slope of the correlation function away from δ∼ 0.8. Using the redshift distribution from the recent I-band selected Canada-France Redshift Survey, the observed w(θ) implies a value of the clustering length r_0 = 1.86 ± 0.43 Mpc (q_0 = 0.5) at z = 0.48. This is generally consistent with the possible rates of clustering evolution expected for optically selected galaxies. We finally discuss the implications of our results for the nature of the faint galaxy population. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9605/9605056v1.pdf"}
{"id": "astro-ph9605071", "abstract": "  The contribution of weakly–magnetized (B∼ 10^9 G) neutron stars accreting the interstellar medium to the diffuse X–ray emission observed in the Galactic Center is investigated. It is shown that, under rather conservative assumptions about the neutron stars and gas distributions, the accretion luminosity can account for a sizable fraction, possibly most, of the detected X–ray flux in the 2.5–7 keV band. In particular, model results are compared with Granat data and show a general agreement in both the flux energy and radial distributions. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9605/9605071v1.pdf"}
{"id": "astro-ph9607113", "abstract": "  Following the recent surge of interest in peculiar galaxies at high redshifts we consider the definition, or lack thereof, of morphological peculiarities on a sample of local universe galaxies. Studying the morphology of local universe galaxies is also of interest in trying to understand galaxy dynamics and quantifying the relations between morphology and environment. We use classifications given by five experts for a sample of 827 APM galaxies and find that there is little agreement between them on what qualifies as a peculiar galaxy. We attempt several objective approaches : matching galaxy images to “templates”; examinig the 180-degree Asymmetry against Light Concentration (following Abraham et al. 1995); and exploring angle-dependent asymmetry measures. While none of the quantities we use results in a clean distinction between normal and peculiar galaxies, there is a rough correlation between some parameters and image peculiarity. However, the mixing between the two classes is significant. We conclude that the class of peculiar galaxies is not totally distinct from the class of normal galaxies, and that what we are seeing is really a sequence. It is therefore more useful to consider distribution functions of morphological parameters. The current and possibly other, more accurate parametrisations require better data, which is becoming available through CCD imaging. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9607/9607113v1.pdf"}
{"id": "astro-ph9610100", "abstract": "  This paper presents the results of a photometric redshift study of galaxies in the Hubble Deep Field (HDF). The method of determining redshifts from broadband colors is described, and the dangers inherent in using it to estimate redshifts, particularly at very high z, are discussed. In particular, the need for accurate high-z spectral energy distributions is illustrated. The validity of our photometric redshift technique is demonstrated both by direct verification with available HDF spectroscopic data and by comparisons of luminosity functions and luminosity densities with those obtained from z < 1 spectroscopic redshift surveys. Evolution of the galaxy population is studied over 0 ≲z < 4. Brightening is seen in both the luminosity function and the luminosity density out to z ≈3; this is followed by a decline in both at z > 3. A population of z < 0.5 star-forming dwarfs is observed to M_F450W_AB = -11. Our results are discussed in the context of recent developments in the understanding of galaxy evolution. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9610/9610100v1.pdf"}
{"id": "astro-ph9610192", "abstract": "  The amount of dark matter in the four galactic dwarf spheroidals with large mass-to-light ratios is investigated. Sextans has a cut-off radius which is equal to the expected tidal radius, assuming a high mass-to-light ratio. This satellite very likely is dark matter dominated. Carina, Ursa Minor and Draco, on the other hand, cannot contain a dominating dark matter component if the observed 'extra-tidal' stars are located exterior to the tidal radii of these systems. The evidence for tidal stripping in the absence of dark matter is also supported by the fact that the observed cut-off radii of all three satellites are equal to their tidal radii, assuming a low, globular cluster like mass-to-light ratio. The large velocity dispersions of these galaxies, on the other hand, seem to provide strong evidence for a massive dark matter component. In this case, the 'extra-tidal' stars lie deeply embedded in the dark matter potential wells of the satellites. These stars then would represent a gravitationally bound, extended stellar component with unknown origin. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9610/9610192v1.pdf"}
{"id": "astro-ph9611050", "abstract": "  The normal mode theory for warping of galaxy disks, in which disks are assumed to be tilted with respect to the equator of a massive, flattened dark halo, assumes a rigid, fixed halo. However, consideration of the back-reaction by a misaligned disk on a massive particle halo shows there to be strong coupling leading to efficient damping (or in some circumstances excitation) of the misalignment, and hence the warp. We therefore discuss possible alternative explanations of the warp phenomenon, with emphasis on the effect of a responsive, gravitationally live massive galactic halo. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9611/9611050v1.pdf"}
{"id": "astro-ph9702189", "abstract": "  The general statement that hypothetical strange (quark matter) stars cool more rapidly than neutron stars is investigated in greater detail. It is found that the direct Urca process could be forbidden not only in neutron stars but also in strange stars. In this case, strange stars are slowly cooling, and their surface temperatures are more or less indistinguishable from those of slowly cooling neutron stars. Furthermore the case of enhanced cooling is reinvestigated. It shows that strange stars cool significantly more rapidly than neutron stars within the first ∼ 30 years after birth. This feature could become particularly interesting if continued observation of SN 1987A would reveal the temperature of the possibly existing pulsar at its center. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9702/9702189v1.pdf"}
{"id": "astro-ph9702203", "abstract": "  We have detected extremely wide (1100 km/s) CO(1-0) emission from NGC 1144, an interacting, luminous infrared galaxy that is the dominant component of the Arp 118 system. The observations show that NGC 1144 is one of the most CO luminous galaxies in the local universe, with a CO luminosity twice that of Arp 220. Maps with the IRAM interferometer show that the CO is not in or very near the Seyfert 2 nucleus, but in the 20 kpc diameter ring that extends halfway between NGC 1144 and the elliptical galaxy NGC 1143. The greatest gas concentration, with 40", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9702/9702203v1.pdf"}
{"id": "astro-ph9703073", "abstract": "  The metallicities derived from spectroscopic observations of a sample of Starburst Nucleus Galaxies (SBNGs) are compared to those of several other types of galaxies (normal giant galaxies, Irregular and HII galaxies) drawn from the literature. The SBNGs are deficient in metals with respect to normal galaxies of same morphological type, suggesting that - SBNGs are galaxies still in the process of formation.   Breaking the SBNGs into early-types (Sb and earlier) and late-types reveals that the former seem to follow the same linear luminosity-metallicity relation as the irregular and elliptical galaxies, whereas the latter and the giant spirals show comparable (0.2 and 0.3 dex) excess abundances with respect to the linear relation. This difference between the two types of SBNGs is consistent with the predictions of the model of hierarchical formation of galaxies: the early-type SBNGs are building their bulges by successive mergers of small stellar and gaseous systems, while the late-type SBNGs are mostly accreting gas to form a disk. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9703/9703073v1.pdf"}
{"id": "astro-ph9708127", "abstract": "  We report the serendipitous detection of an X-ray source, AXJ1749+684, with the ASCA Gas Imaging Spectrometer. AXJ1749+684 is identified with a LINER/starburst-type spiral galaxy KUG 1750+683A at a redshift z = 0.05. It has a hard X-ray spectrum, consistent with that of the X-ray background (XRB) in the 1-10 keV band. Despite the optical classification, the X-ray luminosity cannot be explained by starburst activity. Combined with spatial variations in the optical emission line ratios, this suggests the presence of an obscured Seyfert nucleus embedded within a starforming galaxy. Similar behaviour could explain the ambiguous properties of the faint narrow-line X-ray galaxies (NLXGs) emerging from deep X-ray surveys. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9708/9708127v1.pdf"}
{"id": "astro-ph9709287", "abstract": "  We present new VLA, MERLIN and VLBI images for the radio galaxy 3C 338, and the results of the monitoring of its arcsecond core flux density. Present high sensitivity observations allow us to investigate the radio structure of this source and to confirm the presence of two symmetric parsec scale jets. Morphological changes between different epochs are evident and a proper motion with β∼ 0.4h^-1 has been derived allowing us to give a lower limit constraint for the Hubble constant. While the steep spectrum large scale structure of 3C 338 could be a relic emission, the small scale structure looks young, similar to the high power MSOs found at high redshift. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9709/9709287v1.pdf"}
{"id": "astro-ph9711137", "abstract": "  We present ROSAT PSPC and HRI images of eight galaxies selected from a distance-limited sample of 22 edge-on Seyfert galaxies. Kiloparsec-scale soft X-ray nebulae extend along the galaxy minor axes in three galaxies (NGC 2992, NGC 4388 and NGC 5506). The extended X-ray emission has 0.2-2.4 keV X-ray luminosities of 0.4-3.5 × 10^40 erg s^-1. The X-ray nebulae are roughly co-spatial with the large-scale radio emission, suggesting that both are produced by large-scale galactic outflows. Assuming pressure balance between the radio and X-ray plasmas, the X-ray filling factor is 10^4 times larger than the radio plasma filling factor, suggesting that large-scale outflows in Seyfert galaxies are predominantly winds of thermal X-ray emitting gas. We favor an interpretation in which large-scale outflows originate as AGN-driven jets that entrain and heat gas on kpc scales as they make their way out of the galaxy. AGN- and starburst-driven winds are also possible explanations in cases where the winds are oriented along the rotation axis of the galaxy disk. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9711/9711137v1.pdf"}
{"id": "astro-ph9801219", "abstract": "  Oscillations in the X-ray flux of thermonuclear X-ray bursts have been observed with RXTE from at least 6 low-mass binaries, at frequencies from 330 Hz to 589 Hz. There appear to be preferred relations between the frequencies present during the bursts and those seen in the persistent flux. The amplitude of the oscillations can exceed 50 ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9801/9801219v1.pdf"}
{"id": "astro-ph9801285", "abstract": "  The distribution of the polarization of the Cosmic Microwave Background (CMB) in the sky is determined by the hypothesis of random Gaussian distribution of the primordial density perturbations. This hypotheses is well motivated by the inflationary cosmology. Therefore, the test of consistency of the statistical properties of the CMB polarization field with the Gaussianity of primordial density fluctuations is a realistic way to study the nature of primordial inhomogeneities in the Universe. This paper contains the theoretical predictions of the general statistical properties of the CMB polarization field. All results obtained under assumption of the Gaussian nature of the signal. We pay the special attention to the following two problems. First, the classification and statistics of the singular points of the polarization field where polarization is equal to zero. Second, the topology of contours of the value of the degree of polarization. We have investigated the percolation properties for the zones of “strong” and “weak” polarization. We also have calculated Minkowski functionals for the CMB polarization field. All results are analytical. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9801/9801285v1.pdf"}
{"id": "astro-ph9803217", "abstract": "  We study numerically the evolution of an adiabatic relativistic fireball expanding into a cold uniform medium. We follow the stages of initial free expansion and acceleration, coasting and then deceleration and slowing down to a non-relativistic velocity. We compare the numerical results with simplified analytical estimates. We show that the relativistic self similar Blandford-McKee solution describes well the relativistic deceleration epoch. It is an excellent approximation throughout the relativistic deceleration stage, down to γ∼ 5, and a reasonable approximation even down to γ∼ 2 though the solution is rigorous only for γ≫ 1. We examine the transition into the Blandford-McKee solution, and the transition from the solution to the non-relativistic self similar Sedov-Taylor solution. These simulations demonstrate the attractive nature of the Blandford-McKee solution and its stability to radial perturbations. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9803/9803217v1.pdf"}
{"id": "astro-ph9804056", "abstract": "  We present the results of soft X-ray observations of the intermediate-age open cluster IC 4651 performed with the ROSAT PSPC. We detected 25 sources. Two are identified with a giant binary and a blue straggler respectively, both belonging to the cluster, and two with probable main-sequence members. Two other cases have ambiguous identification. Of the five binaries known in the cluster, the one detected in X rays is the only one whose period is short enough to maintain fast rotation and therefore strong stellar activity at a high age. The detected blue straggler is probably binary, suggesting that binarity is the key to producing a high level of X-ray emission. It is the third blue straggler detected in X rays. The remaining sources need to be identified through optical follow-up. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9804/9804056v1.pdf"}
{"id": "astro-ph9804128", "abstract": "  We analyze RXTE/PCA observations of the black hole candidate and galactic superluminal source GRO J1655-40 during its recent outburst. We show that during its decay to quiescence, GRO J1655-40 goes through the high, intermediate, and low state (and that at the beginning of its decay it might have even shown signatures of a very high state), just like other black hole candidates. This is the first time that such a transition is observed in a galactic superluminal source. We discuss what are the implications of these results on the hypothesis that the spin of the black hole in superluminal sources is much higher than in other black hole candidates. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9804/9804128v1.pdf"}
{"id": "astro-ph9805030", "abstract": "  The determination of the “Fundamental Parameters” T_eff and log g for a set of dwarf A0-type stars is discussed in terms of consistency when comparing these values determined through different methods. The position of these stars in the HR diagram are discussed, taking into account the HIPPARCOS data. A large number of binary stars with components of similar spectral types has been found from this spectroscopic survey. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9805/9805030v1.pdf"}
{"id": "astro-ph9805065", "abstract": "  Doppler imaging, a technique which inverts spectral line profile variations of an Ap star into a two-dimensional abundance maps, provides new observational constraints on diffusion mechanism in the presence of a global magnetic field. A programme is presented here with the aim to obtain abundance distributions of at least five elements on each star, in order to study how different diffusion processes act under influence of a stellar magnetic field. The importance of this multi-element approach is demonstrated, by presenting the abundance maps of helium, magnesium, silicon, chromium and iron for the magnetic B9pSi star CU Virginis. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9805/9805065v1.pdf"}
{"id": "astro-ph9806080", "abstract": "  We calculate the expected number of multiply-imaged galaxies in the Hubble Deep Field (HDF), using photometric redshift information for galaxies with m_I < 27 that were detected in all four HDF passbands. A comparison of these expectations with the observed number of strongly lensed galaxies places a lower limit on the current value of Ω_m-Ω_Λ, where Ω_m is the cosmological mass density of the universe and Ω_Λ is the normalized cosmological constant. Based on current estimates of the HDF luminosity function and associated uncertainties in individual parameters, our 95", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9806/9806080v3.pdf"}
{"id": "astro-ph9806306", "abstract": "  If the Galactic rotation speed at the Solar circle is ∼ 200 km s^-1 or smaller, which is supported by several recent studies, the rotation curve of the Galaxy could be declining in the outermost region. Motivated by this, we investigate the effect of such declining rotation curve on the estimate of the MACHO mass and the fractional contribution of the MACHOs to the Galactic dark halo. Using Hernquist and Plummer halo models instead of the standard halo model, we find that the MACHO mass could be significantly smaller than that for the standard halo case. In particular, there exists a certain set of halo parameters for which the MACHO mass is 0.1M_⊙ or less and at the same time the MACHO contribution to the total mass of the halo is almost 100 ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9806/9806306v1.pdf"}
{"id": "astro-ph9806360", "abstract": "  The results of numerical simulations are presented which demonstrate that liquid mirror telescope galaxy redshift surveys such as the current UBC-NASA Multi-Narrowband Survey and the future LZT Survey have the potential of discriminating between the predictions of different theories of structure formation. Most of the currently studied theories of structure formation predict a scale-invariant spectrum of primordial perturbations. Therefore, to distinguish between the predictions of the various models, we make use of statistics which are sensitive to non-Gaussian phases, such as the counts in cell statistics, N-galaxy probability functions and Minkowski functionals. It is shown that already the current UBC-NASA survey can clearly differentiate between the predictions of some topological defect theories and those of inflationary Universe models with Gaussian phases. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9806/9806360v1.pdf"}
{"id": "astro-ph9807141", "abstract": "  This paper presents first results on the line profile shapes from a circumstellar envelope in bulk motion as modified by a microlensing event. Only geometrically and optically thin spherical shells in uniform expansion or rotation are considered here so as to emphasise the information content available in the profile shapes. In particular it is demonstrated that for the case of expansion, the line emission can increase by significant factors and the time variation of the profile shape is symmetric about line centre. For uniform rotation the line emission also increases significantly, but the time evolution of the profile shape is distinctly asymmetric. Thus, microlensing is seen to yield information about the velocity field in the extended envelope. We elaborate on (a) the observational advantages of tailoring microlensing programs toward detecting extended circumstellar envelopes, (b) the use of multiline observations to infer other properties of the envelopes, such as the ionization stratification, (c) the use of the continuum excess emission at infrared wavelengths as a means of probing the envelope structure, and (d) the use of polarisation for constraining the properties of “clumpy” winds. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9807/9807141v1.pdf"}
{"id": "astro-ph9810349", "abstract": "  We analyze the distribution of galaxy HI masses detected in a large, deep HI survey conducted at the Arecibo observatory, and we find possible evidence of a faint-end steepening of the mass function similar to what has been found optically. This is the first HI survey with enough dynamic range to see this steepening; the results of an earlier survey are found to be consistent when the detection statistics are re-examined. We demonstrate a technique for testing and correcting source count completeness in HI surveys based on the V/V_max test and the large scale structure in the regions surveyed. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9810/9810349v1.pdf"}
{"id": "astro-ph9811366", "abstract": "  For two decades the hot big-bang model as been referred to as the standard cosmology – and for good reason. For just as long cosmologists have known that there are fundamental questions that are not answered by the standard cosmology and point to a grander theory. The best candidate for that grander theory is inflation + cold dark matter. It holds that the Universe is flat, that slowly moving elementary particles left over from the earliest moments provide the cosmic infrastructure, and that the primeval density inhomogeneities that seed all the structure arose from quantum fluctuations. There is now prima facie evidence that supports two basic tenets of this paradigm. An avalanche of high-quality cosmological observations will soon make this case stronger or will break it. Key questions remain to be answered; foremost among them are: identification and detection of the cold dark matter particles and elucidation of the dark-energy component. These are exciting times in cosmology! ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9811/9811366v1.pdf"}
{"id": "astro-ph9811415", "abstract": "  We compute mass outflow rate R_ṁ from relativistic matter accreting quasi-spherically onto Schwarzschild black holes. Taking the pair-plasma pressure mediated shock surface as the effective boundary layer (of the black hole) from where bulk of the outflow is assumed to be generated, computation of this rate is done using combinations of exact transonic inflow and outflow solutions. We find that R_ṁ depends on the initial parameters of the flow, the polytropic index of matter, the degree of compression of matter near the shock surface and on the location of the shock surface itself. We thus not only study the variation of the mass outflow rate as a function of various physical parameters governing the problem but also provide a sufficiently plausible estimation of this rate. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9811/9811415v2.pdf"}
{"id": "astro-ph9812068", "abstract": "  Extensive grids of photoionization models have been calculated for single star HII regions and evolving starbursts. We illustrate the predictions for IR fine structure lines which are used to analyse the stellar content, and derive properties such as the age and IMF. The impact of recent ionizing fluxes on the IR lines are shown. First comparisons of our starburst models with IR-diagnostics and the ISO observations of Genzel et al. (1998) are also presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9812/9812068v1.pdf"}
{"id": "astro-ph9812092", "abstract": "  We outline reasoning that led to the current theory of quasars and look at George Contopoulos's place in the long history of the N-body problem. Following Newton we find new exactly soluble N-body problems with multibody forces and give a strange eternally pulsating system that in its other degrees of freedom reaches statistical equilibrium. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9812/9812092v1.pdf"}
{"id": "astro-ph9902382", "abstract": "  We undertook a long term project, DIRECT, to obtain the direct distances to two important galaxies in the cosmological distance ladder – M31 and M33 – using detached eclipsing binaries (DEBs) and Cepheids. While rare and difficult to detect, DEBs provide us with the potential to determine these distances with an accuracy better than 5", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9902/9902382v2.pdf"}
{"id": "astro-ph9904355", "abstract": "  We present a study on the possible association of unidentified γ-ray sources in the Third EGRET (3EG) catalog with different types of galactic objects such as Wolf-Rayet and Of stars, supernova remnants (SNRs), and OB associations (considered as pulsar tracers). We have made use of numerical simulations of galactic populations of γ-ray point sources in order to determine the statistical significance of the positional coincidences. New constraints on pure chance association are presented for SNRs and OB associations, and it is shown that massive stars present marginally significant correlation with 3EG sources at a 3σ level. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9904/9904355v1.pdf"}
{"id": "astro-ph9905190", "abstract": "  We are using optical/IR surface brightness fluctuations (SBFs) to validate the latest stellar population synthesis models and to understand the stellar populations of ellipticals. Integrated light and spectra measure only the first moment of the stellar luminosity function (Σn_i * L_i). Since SBFs also depend on the second moment (Σn_i * L_i^2), they provide novel information, in particular about the reddest, most luminous RGB and AGB stars, which are the most difficult stars to model. SBFs can also provide useful new constraints on the age/metallicity of unresolved stellar populations in ellipticals. Finally, developing accurate stellar population models benefits several aspects of SBF distance measurements to galaxies. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9905/9905190v1.pdf"}
{"id": "astro-ph9906181", "abstract": "  In this paper we present a neural network based estimator system which performs well the frequency extraction from unevenly sampled signals. It uses an unsupervised Hebbian nonlinear neural algorithm to extract the principal components which, in turn, are used by the MUSIC frequency estimator algorithm to extract the frequencies. We generalize this method to avoid an interpolation preprocessing step and to improve the performance by using a new stop criterion to avoid overfitting. The experimental results are obtained comparing our methodology with the others known in literature. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9906/9906181v2.pdf"}
{"id": "astro-ph9908136", "abstract": "  We show that the distribution of observed energies of GRB with known redshifts can be explained by the hypothesis of the standard energy release E_0=5 10^51 ergs. Two situations are possible, either the beaming angle differs from burst to burst, or there is a universal emssion diagram in each burst, the observed difference being due to different viewing angles. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9908/9908136v1.pdf"}
{"id": "astro-ph9908359", "abstract": "  By using the Cowling approximation, quasi-radial modes of rotating general relativistic stars are computed along equilibrium sequences from non-rotating to maximally rotating models. The eigenfrequencies of these modes are decreasing functions of the rotational frequency. The eigenfrequency curve of each mode as a function of the rotational frequency has discontinuities, which arise from the avoided crossing with other curves of axisymmetric modes. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9908/9908359v3.pdf"}
{"id": "astro-ph9909086", "abstract": "  We present an infrared imaging study of the low-mass pre-main sequence binary system Haro 6-10. This system is one of a handful in which the optically-visible primary has the characteristics of a normal T Tauri star, while the secondary is a so-called \"infrared companion\" (IRC), a strongly extincted object which emits most of its luminosity in the infrared. A speckle holographic technique was used to produce nearly diffraction-limited images on three nights over a one-year period starting in late 1997. The images show that the IRC is obscured and surrounded by a compact, irregular, and variable nebula. This structure is in striking contrast to the well-ordered edge-on disk associated with HK Tauri B, the extincted companion to another T Tauri star of similar age. A new, resolved intensity peak was found 0\".4 southwest of the IRC. We suggest that it may represent light scattered by a clump of dusty material illuminated by starlight escaping along an outflow-carved cavity in the IRC envelope. The primary star became fainter and the companion became more extended during the observing period. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9909/9909086v1.pdf"}
{"id": "astro-ph9910190", "abstract": "  We present H-band observations of gravitationally lensed QSO host galaxies obtained with NICMOS on HST as part of the CfA-Arizona-Gravitational-Lens-Survey (CASTLES). The detections are greatly facilitated by the lensing magnification in these systems; we find that most hosts of radio-quiet QSOs (RQQ) at z 2 are of modest luminosity (L<L_*). They are 2-5 times fainter than the hosts of radio-loud QSOs at the same epoch. Compared to low redshifts, RQQ hosts at z 2 also support higher nuclear luminosities at given stellar host mass. This suggests that the supermassive black holes at their centers grew faster at early epochs than the stellar body of their surrounding host galaxies. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9910/9910190v1.pdf"}
{"id": "astro-ph9910378", "abstract": "  Narrow-band Hα and [N ii] images and high-dispersion spatially-resolved echelle spectroscopy of the planetary nebula NGC 6891 are presented. These observations show a great wealth of structures. The bright central nebula is surrounded by an attached shell and a detached outer halo. Both the inner and intermediate shells can be described as ellipsoids with similar major to minor axial ratios, but different spatial orientations. The kinematical ages of the intermediate shell and halo are 4,800 and 28,000 years, respectively. The inter-shell time lapse is in good agreement with the evolutionary inter-pulse time lapse. A highly collimated outflow is observed to protrude from the tips of the major axis of the inner nebula and impact on the outer edge of the intermediate shell. Kinematics and excitation of this outflow provide conclusive evidence that it is deflected during the interaction with the outer edge of the intermediate shell. At the same time, both the kinematics and the morphology of the intermediate shell appear to be affected by this interaction. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9910/9910378v1.pdf"}
{"id": "astro-ph9912305", "abstract": "  A catalog of nearby clusters in the 5800 deg^2 area in the southern Galactic cap is constructed by applying a matched-filter cluster-finding algorithm to the sample of 3.3 million galaxies from the APM Galaxy Survey. I have preliminarily detected more than 4000 cluster candidates with estimated redshift of less than 0.2 and with richness similar to those of ACO clusters. Generally, a good correspondence is found between the nearest cluster candidates in our catalog and the ACO clusters which have measured redshift. While the ACO catalog becomes incomplete at z>0.08, the completeness limit of our cluster catalog reaches z=0.15. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9912/9912305v1.pdf"}
{"id": "atom-ph9605006", "abstract": "  We investigate an atomic three-level Λ-system which is exposed to two counterpropagating laser fields (inducing Raman transitions) and which is closed by a magnetic hyperfine field tuned to be in resonance with the transition between the two ground states. The influence of a homogeneous gravitational field is included in a full quantum treatment of the internal and external dynamics of the atom. It is shown that the combined influence of the gravitational field and the lasers lead for specific momentum values with a very high probability to a transition of the Landau-Zener type. This is accompanied by a momentum transfer resulting in an upward kick. For appropriate initial conditions a sequence of up and down motions is obtained. No mirror is needed. A gravito-optical trapping of atoms based on this effect seems to be realizable. ", "pdf_url": "gs://arxiv-dataset/arxiv/atom-ph/pdf/9605/9605006v1.pdf"}
{"id": "chao-dyn9903009", "abstract": "  The paper examines the discrete-time dynamics of neuron models (of excitatory and inhibitory types) with piecewise linear activation functions, which are connected in a network. The properties of a pair of neurons (one excitatory and the other inhibitory) connected with each other, is studied in detail. Even such a simple system shows a rich variety of behavior, including high-period oscillations and chaos. Border-collision bifurcations and multifractal fragmentation of the phase space is also observed for a range of parameter values. Extension of the model to a larger number of neurons is suggested under certain restrictive assumptions, which makes the resultant network dynamics effectively one-dimensional. Possible applications of the network for information processing are outlined. These include using the network for auto-association, pattern classification, nonlinear function approximation and periodic sequence generation. ", "pdf_url": "gs://arxiv-dataset/arxiv/chao-dyn/pdf/9903/9903009v1.pdf"}
{"id": "chao-dyn9903025", "abstract": "  We apply periodic orbit theory to study the asymptotic distribution of escape times from an intermittent map. The dynamical zeta function exhibits a branch point which is associated with an asymptotic power law escape. By an analytic continuation technique we compute a zero of the zeta function beyond its radius of convergence leading to a pre-asymptotic exponential decay. The time of crossover from an exponential to a power law is also predicted. The theoretical predictions are confirmed by numerical simulation. Applications to conductance fluctuations in quantum dots are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/chao-dyn/pdf/9903/9903025v2.pdf"}
{"id": "cmp-lg9505042", "abstract": "  In a consistent text, many words and phrases are repeatedly used in more than one sentence. When an identical phrase (a set of consecutive words) is repeated in different sentences, the constituent words of those sentences tend to be associated in identical modification patterns with identical parts of speech and identical modifiee-modifier relationships. Thus, when a syntactic parser cannot parse a sentence as a unified structure, parts of speech and modifiee-modifier relationships among morphologically identical words in complete parses of other sentences within the same text provide useful information for obtaining partial parses of the sentence. In this paper, we describe a method for completing partial parses by maintaining consistency among morphologically identical words within the same text as regards their part of speech and their modifiee-modifier relationship. The experimental results obtained by using this method with technical documents offer good prospects for improving the accuracy of sentence analysis in a broad-coverage natural language processing system such as a machine translation system. ", "pdf_url": "gs://arxiv-dataset/arxiv/cmp-lg/pdf/9505/9505042v1.pdf"}
{"id": "cmp-lg9808004", "abstract": "  Recent observations in the theory of verse and empirical metrics have suggested that constructing a verse line involves a pattern-matching search through a source text, and that the number of found elements (complete words totaling a specified number of syllables) is given by dividing the total number of words by the mean number of syllables per word in the source text. This paper makes this latter point explicit mathematically, and in the course of this demonstration shows that the word length frequency totals in English output are distributed geometrically (previous researchers reported an adjusted Poisson distribution), and that the sequential distribution is random at the global level, with significant non-randomness in the fine structure. Data from a corpus of just under two million words, and a syllable-count lexicon of 71,000 word-forms is reported. The pattern-matching theory is shown to be internally coherent, and it is observed that some of the analytic techniques described here form a satisfactory test for regular (isometric) lineation in a text. ", "pdf_url": "gs://arxiv-dataset/arxiv/cmp-lg/pdf/9808/9808004v2.pdf"}
{"id": "comp-gas9509003", "abstract": "  The method of surrogate data is a tool to test whether data were generated by some class of model. Tests based on the periodogram have been proposed to decide if linear systems driven by Gaussian noise could have generated a sample time series. We show that this procedure based on the periodogram, in general, misspecifies the test statistic. Based on the theory of linear systems we suggest an alternative procedure to obtain the correct distribution of the test statistic and discuss problems of this approach. ", "pdf_url": "gs://arxiv-dataset/arxiv/comp-gas/pdf/9509/9509003v1.pdf"}
{"id": "cond-mat0002269", "abstract": "  We use the Path Integral Monte Carlo method to investigate the interplay between shell effects and electron correlations in single quantum dots with up to 12 electrons. By use of an energy estimator based on the hypervirial theorem of Hirschfelder we study the energy contributions of different interaction terms in detail. We discuss under which conditions the total spin of the electrons is given by Hund's rule, and the temperature dependence of the crystallization effects. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0002/0002269v2.pdf"}
{"id": "cond-mat0003248", "abstract": "  Calculations of Raman scattering intensities in spin 1/2 square-lattice Heisenberg model, using the Fleury-Loudon-Elliott theory, have so far been unable to describe the broad line shape and asymmetry of the two magnon peak found experimentally in the cuprate materials. Even more notably, the polarization selection rules are violated with respect to the Fleury-Loudon-Elliott theory. There is comparable scattering in B_1g and A_1g geometries, whereas the theory would predict scattering in only B_1g geometry. We review various suggestions for this discrepency and suggest that at least part of the problem can be addressed by modifying the effective Raman Hamiltonian, allowing for two-magnon states with arbitrary total momentum. Such an approach based on the Sawatzsky-Lorenzana theory of optical absorption assumes an important role of phonons as momentum sinks. It leaves the low energy physics of the Heisenberg model unchanged but substantially alters the Raman line-shape and selection rules, bringing the results closer to experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0003/0003248v2.pdf"}
{"id": "cond-mat0008318", "abstract": "  We propose a new way to treat nuclear magnetism of solid ^3He. We argue that the magnetic interaction arises indirectly as a consequence of correlated zero-point motion of the ions. This motion lowers the energy of the ground state, and results in a coherent state of oscillating electric dipoles. Distortion of the electronic wavefunctions leads to hyperfine magnetic interactions with the nuclear spin.   Our model describes both the phonon spectra and the nuclear magnetic ordering of bcc ^3He using a single parameter, the dipolar interaction energy E_0. The model yields correctly both the u2d2 symmetry of the ordered phase and the volume dependence of the magnetic interaction. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0008/0008318v1.pdf"}
{"id": "cond-mat0009330", "abstract": "  In an effort to understand the low temperature behavior of recently synthesized molecular magnets we present numerical evidence for the existence of a rotational band in systems of quantum spins interacting with nearest-neighbor antiferromagnetic Heisenberg exchange. While this result has previously been noted for ring arrays with an even number of spin sites, we find that it also applies for rings with an odd number of sites as well as for all of the polytope configurations we have investigated (tetrahedron, cube, octahedron, icosahedron, triangular prism, and axially truncated icosahedron). It is demonstrated how the rotational band levels can in many cases be accurately predicted using the underlying sublattice structure of the spin array. We illustrate how the characteristics of the rotational band can provide valuable estimates for the low temperature magnetic susceptibility. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0009/0009330v1.pdf"}
{"id": "cond-mat0009419", "abstract": "  We consider the tunneling of localized excitations (many boson bound states) in the presence of a bosonic bath. We show both analytically and numerically that the bath influence results in a dramatical enhancement of the amplitude of the excitation tunneling. The order of the bosonic flow in the course of the tunneling process is obtained. On the background of the giant tunneling enhancement we observe and describe additional resonant enhancement and suppression of tunneling due to avoided level crossings. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0009/0009419v1.pdf"}
{"id": "cond-mat0101118", "abstract": "  In the present paper we overview our recent results on intrinsic frictional properties of adsorbed monolayers, composed of mobile hard-core particles undergoing continuous exchanges with a vapor phase. Within the framework of a dynamical master equation approach, describing the time evolution of the system, we determine in the most general form the terminal velocity of some biased impure molecule - the tracer particle (TP), constrained to move inside the adsorbed monolayer probing its frictional properties, define the frictional forces as well as the particles density distribution in the monolayer. Results for one-dimensional solid substrates, appropriate to adsorbtion on polymer chains, are compared against the Monte Carlo simulation data, which confirms our analytical predictions. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0101/0101118v1.pdf"}
{"id": "cond-mat0101369", "abstract": "  We review microstructural fracture growth models suitable for the study of hydraulic fracture processes in disordered porous materials and present some basic results. It is shown that microstructural models exhibit certain similarities to corresponding theories of continua. These similarities are most easily demonstrated for simple crack geometries, i.e., straight cracks (finite size scalings). However, there exist even scaling relations which are completely independent of the particular employed crack structure. Furthermore it is demonstrated that disorder in cohesional/flow properties can influence the crack growth and the resulting fracture geometry in an essential way. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0101/0101369v1.pdf"}
{"id": "cond-mat0103206", "abstract": "  We calculate the two, three, four, and five-body (state independent) effective potentials between the centers of mass (CM) of self avoiding walk polymers by Monte-Carlo simulations. For full overlap, these coarse-grained n-body interactions oscillate in sign as (-1)^n, and decrease in absolute magnitude with increasing n. We find semi-quantitative agreement with a scaling theory, and use this to discuss how the coarse-grained free energy converges when expanded to arbitrary order in the many-body potentials. We also derive effective density dependent 2-body potentials which exactly reproduce the pair-correlations between the CM of the self avoiding walk polymers. The density dependence of these pair potentials can be largely understood from the effects of the density independent 3-body potential. Triplet correlations between the CM of the polymers are surprisingly well, but not exactly, described by our coarse-grained effective pair potential picture. In fact, we demonstrate that a pair-potential cannot simultaneously reproduce the two and three body correlations in a system with many-body interactions. However, the deviations that do occur in our system are very small, and can be explained by the direct influence of 3-body potentials. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0103/0103206v1.pdf"}
{"id": "cond-mat0103268", "abstract": "  Motivated by recent phonon spectroscopy experiments in the fractional quantum Hall regime we consider processes in which thermally excited magnetoroton excitations are scattered by low energy phonons. We show that such scattering processes can never give rise to dissociation of magnetorotons into unbound charged quasiparticles as had been proposed previously. In addition we show that scattering of magnetorotons to longer wavelengths by phonon absorption is possible because of the shape of the magnetoroton dispersion curve and it is shown that there is a characteristic cross-over temperature above which the rate of energy transfer to the electron gas changes from an exponential (activated) to a power law dependence on the effective phonon temperature. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0103/0103268v1.pdf"}
{"id": "cond-mat0103487", "abstract": "  Measurements of x-ray emission and absorption spectra of the constituents of MgB_2 are presented. The results obtained are in good agreement with calculated x-ray spectra, with dipole matrix elements taken into account. The comparison of x-ray emission spectra of graphite, AlB_2, and MgB_2 in the binding energy scale supports the idea of charge transfer from σ to π bands, which creates holes at the top of the bonding σ bands and drives the high-T_c ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0103/0103487v3.pdf"}
{"id": "cond-mat0104006", "abstract": "  Short length quantum wires (quantum contacts) exhibit a conductance structure at the value of conductance close to 0.7 ×2e^2/h. The structure is also called the conductance anomaly. In longer contacts the structure evolves to the lower values of conductance. We demonstrate that this structure is related to the development of charge density waves within the contact. This is a precursor for Wigner crystallization. Many-body Hartree-Fock calculations of conductance are performed. The results are in agreement with experimental data. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0104/0104006v2.pdf"}
{"id": "cond-mat0104452", "abstract": "  Combining scanning electron microscopy (SEM) and electron-beam-induced current (EBIC) imaging with transport measurements, it is shown that the current flowing across a two-terminal oxide-based capacitor-like structure is preferentially confined in areas localized at defects. As the thin-film device switches between two different resistance states, the distribution and intensity of the current paths, appearing as bright spots, change. This implies that switching and memory effects are mainly determined by the conducting properties along such paths. A model based on the storage and release of charge carriers within the insulator seems adequate to explain the observed memory effect. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0104/0104452v1.pdf"}
{"id": "cond-mat0105340", "abstract": "  Protein folds are highly designable, in the sense that many sequences fold to the same conformation. In the present work we derive an expression for the designability in a 20 letter lattice model of proteins which, relying only on the Central Limit Theorem, has a generality which goes beyond the simple model used in its derivation. This expression displays an exponential dependence on the energy of the optimal sequence folding on the given conformation measured with respect to the lowest energy of the conformational dissimilar structures, energy difference which constitutes the only parameter controlling designability. Accordingly, the designability of a native conformation is intimately connected to the stability of the sequences folding to them. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0105/0105340v1.pdf"}
{"id": "cond-mat0106215", "abstract": "  In the present paper we study chemical potential of the generalized Hubbard model with correlated hopping. The peculiarity of the model in comparison with similar generalized Hubbard models is the concentration dependence of hopping integrals. Chemical potential as a function of the model energy parameters, electron concentration and temperature is found. It is shown that correlated hopping and temperature changes essentially the chemical potential location; these dependencies differ strongly at different values of the electron concenntration. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0106/0106215v1.pdf"}
{"id": "cond-mat0106531", "abstract": "  We study the Aharonov-Bohm effect in a coupled 2×2 quantum dot array with two-terminals. A striking conductance dip arising from the Fano interference is found as the energy levels of the intermediate dots are mismatched, which is lifted in the presence of a magnetic flux. A novel five peak structure is observed in the conductance for large mismatch. The Aharonov-Bohm evolution of the linear conductance strongly depends on the configuration of dot levels and interdot and dot-lead coupling strengths. In addition, the magnetic flux and asymmetry between dot-lead couplings can induce the splitting and combination of the conductance peak(s). ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0106/0106531v3.pdf"}
{"id": "cond-mat0108189", "abstract": "  We present the circuit equivalent of the Landau-Khalatnikov dynamical ferroelectric model. The differential equation for hysteretic behavior is subject to numerical computer simulations. The size and shape of the simulated hysteretic loops depends strongly on the frequency and the amplitude of the driving electric field. This dependence makes the experimental extraction of the coercive electric field difficult. The bifurcation of the driven Landau-Khalatnikov model is explained in detail. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0108/0108189v1.pdf"}
{"id": "cond-mat0110103", "abstract": "  We discuss numerical and theoretical results for models of magnetization switching in nanoparticles and ultrathin films. The models and computational methods include kinetic Ising and classical Heisenberg models of highly anisotropic magnets which are simulated by dynamic Monte Carlo methods, and micromagnetics models of continuum-spin systems that are studied by finite-temperature Langevin simulations. The theoretical analysis builds on the fact that a magnetic particle or film that is magnetized in a direction antiparallel to the applied field is in a metastable state. Nucleation theory is therefore used to analyze magnetization reversal as the decay of this metastable phase to equilibrium. We present numerical results on magnetization reversal in models of nanoparticles and films, and on hysteresis in magnets driven by oscillating external fields. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0110/0110103v1.pdf"}
{"id": "cond-mat0110501", "abstract": "  We present a new simulation scheme based on the Lattice-Boltzmann method to simulate the dynamics of charged colloids in an electrolyte. In our model we describe the electrostatics on the level of a Poisson-Boltzmann equation and the hydrodynamics of the fluid by the linearized Navier-Stokes equations. We verify our simulation scheme by means of a Chapman-Enskog expansion. Our method is applied to the calculation of the reduced sedimentation velocity U/U_0 for a cubic array of charged spheres in an electrolyte. We show that we recover the analytical solution first derived by Booth (F. Booth, J. Chem. Phys. 22, 1956 (1954)) for a weakly charged, isolated sphere in an unbounded electrolyte. The present method makes it possible to go beyond the Booth theory, and we discuss the dependence of the sedimentation velocity on the charge of the spheres. Finally we compare our results to experimental data. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0110/0110501v1.pdf"}
{"id": "cond-mat0111012", "abstract": "  The specific heat of the Coulomb glass is studied by numerical simulations. Both the lattice model with various strengths of disorder, and the random-position model are considered for the one- to three-dimensional cases. In order to extend the investigations down to very low temperatures where the many-valley structure of the configuration space is of great importance we use a hybrid-Metropolis procedure. This algorithm bridges the gap between Metropolis simulation and analytical statistical mechanics. The analysis of the simulation results shows that the correlation length of the relevant processes is rather small, and that multi-particle processes yield an essential contribution to the specific heat in all cases except the one-dimensional random-position model. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0111/0111012v1.pdf"}
{"id": "cond-mat0203399", "abstract": "  The results of R^2 dynamical random surface model (2-dimensional quantum gravity with a R^2 term) are applied to explain the personal income distribution. A scale invariance exists if there is not the R^2 term in the action. The R^2 term provides a typical scale and breaks the scale invariance explicitly in the low and middle income range. A new distribution, Weibull distribution, is deduced from the action analytically in the low income range, and a consistent fitting is obtained in the whole income range. Also, we show that the lognormal distribution in the middle income range can be understood in this framework. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0203/0203399v1.pdf"}
{"id": "cond-mat0205166", "abstract": "  We study a mechanism for superconductivity in quasi-one-dimensional materials with Ising anisotropy. In an isolated chain Ising anisotropy opens a spin gap; if inter-chain coupling is sufficiently weak, single particle hopping is suppressed and the physics of coupled chains is controlled by a competition between pair hopping and exchange interaction. Spin density wave and triplet superconductivity phases are found separated by a first order phase transition. For particular parameter values a second order transition described by SO(4) symmetry is found. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0205/0205166v1.pdf"}
{"id": "cond-mat0205337", "abstract": "  It is well known that the particles in a beam of Boson obeying Bose-Einstein statistics tend to cluster (bunching effect), while the particles in a degenerate beam of Fermion obeying Fermi-Dirac statistics expel each other (anti-bunching effect). Here we investigate, for the first time, the statistical correlation effect for the composite Boson, which is formed from a spin singlet entangled electron pair. By using nonequilibrium Green's function technique, we obtain a positive cross correlation for this kind of the composite Boson when the external voltage is smaller than the gap energy, which demonstrates that a spin singlet entangled electron pair looks like a composite Boson. In the larger voltage limit, the cross correlation becomes negative due to the contribution of the quasiparticles. At large voltages, the oscillation between Fermionic and Bosonic behavior of cross correlation is also observed in the strong coupling regime as one changes the position of the resonant levels. Our result can be easily tested in a three-terminal normal-superconductor-superconductor (N-S-S) hybrid mesoscopic system. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0205/0205337v1.pdf"}
{"id": "cond-mat0207588", "abstract": "  Complex systems can exhibit unexpected large changes, e.g. a crash in a financial market. We examine the large endogenous changes arising within a non-trivial generalization of the Minority Game: the Grand Canonical Minority Game (GCMG). Using a Markov Chain description, we study the many possible paths the system may take. This 'many-worlds' view not only allows us to predict the start and end of a crash in this system, but also to investigate how such a crash may be avoided. We find that the system can be 'immunized' against large changes: by inducing small changes today, much larger changes in the future can be prevented. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0207/0207588v1.pdf"}
{"id": "cond-mat0208379", "abstract": "  We investigate discrepancies between recent experimental results on transport through one-dimensional quantum dots and universal power laws predicted by an idealized Luttinger Liquid description. The temperature dependence of Coulomb blockade peaks in one-dimensional quantum dots obeys non-universal power-laws from which different values of the interaction strength can be deduced. We find that, depending on the temperature range, measurements probe local or global properties of the interaction. In particular, we investigate the role of contacting semiconductor quantum wires and nanotubes connected to leads through tunnel junctions and compare to recent experiments. We conclude that a conventional Luttinger Liquid description of the quantum wire does explain the observed behaviour if specific properties of either experimental setup are carefully taken into account. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0208/0208379v1.pdf"}
{"id": "cond-mat0208605", "abstract": "  We present experimental observation of broken-symmetry states in a superconducting loop with three Josephson junctions. These states are generic for discrete breathers in Josephson ladders. The existence region of the breather-like states is found to be in good accordance with the theoretical expectations. We observed three different resonant states in the current-voltage characteristics of the broken-symmetry state, as predicted by theory. The experimental dependence of the resonances on the external magnetic field is studied in detail. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0208/0208605v1.pdf"}
{"id": "cond-mat0209022", "abstract": "  We study the influence of the repulsive Coulomb interactions on thermodynamic properties of the boson fermion model with an anisotropic (d-wave, and extended s-wave) order parameter. Superconductivity is induced in this model from the anisotropic charge exchange interaction between the conduction band fermions (electrons or holes) and the immobile hard-core bosons (the localized electron pairs). The on-site Coulomb repulsion competes with this pairing interaction and hence is expected to have a detrimental influence on superconductivity. We analyze this effect in some detail considering the two opposite limits of: the weak and strong repulsion. A possible crossover between both these regimes is also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0209/0209022v1.pdf"}
{"id": "cond-mat0210636", "abstract": "  We present here a microscopic study of the effect of shear on a dense purely repulsive colloidal suspension. We use Multispeckle Diffusing Wave Spectroscopy to monitor the transient motions of colloidal particles after being submitted to an oscillatory strain. This technique proves efficient to record the time evolution of the relaxation times distribution. After a high oscillatory shear, we show that this distribution displays a full aging behavior. Oppositely, when a moderate shear is applied the distribution is modified in a non trivial way. Whereas high shear is able to erase all the sample history and rejuvenate it, a moderate shear helps it to age. We call this phenomena overaging. We demonstrate that overaging can be understood if the complete shape of the relaxation time distribution is taken into account. We finally report how the Soft Glassy Rheology model accounts for this effect. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0210/0210636v1.pdf"}
{"id": "cond-mat0211355", "abstract": "  We consider possible superconducting instabilities in a two-dimensional Fermi system with short-ranged repulsive interactions between electrons. The possibility of an unusual superconducting paring due to the Kohn-Luttinger mechanism is examined. The quasiparticle scattering amplitude is shown to possess an attractive harmonic in second-order perturbation theory for finite values of the energy transfer. The corresponding singularity in the pairing vertex leads to a superconducting pairing of the electron excitations with finite energies. We identify the energy transfer in the Cooper channel as the binding energy of the excited pair. At low enough temperatures, the Fermi system is a mixture of normal electron excitations and fluctuating d-wave Cooper pairs possessing a finite gap. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0211/0211355v2.pdf"}
{"id": "cond-mat0211472", "abstract": "  We consider the asymmetric random average process which is a one-dimensional stochastic lattice model with nearest neighbour interaction but continuous and unbounded state variables. First, the explicit functional representations, so-called beta densities, of all local interactions leading to steady states of product measure form are rigorously derived. This also completes an outstanding proof given in a previous publication. Then, we present an alternative solution for the processes with factorized stationary states by using a matrix product ansatz. Due to continuous state variables we obtain a matrix algebra in form of a functional equation which can be solved exactly. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0211/0211472v1.pdf"}
{"id": "cond-mat0212268", "abstract": "  We modify and extend the recently developed statistical mechanical model for predicting the thermodynamic properties of chain molecules having noncovalent double-stranded conformations, as in RNA or ssDNA, and β-sheets in protein, by including the constant force stretching at one end of molecules as in a typical single-molecule experiment. The conformations of double-stranded regions of the chain are calculated based on polymer graph-theoretic approach [S-J. Chen and K. A. Dill, J. Chem. Phys. 109, 4602(1998)], while the unpaired single-stranded regions are treated as self-avoiding walks. Sequence dependence and excluded volume interaction are taken into account explicitly. Two classes of conformations, hairpin and RNA secondary structure are explored. For the hairpin conformations, all possible end-to-end distances corresponding to the different types of double-stranded regions are enumerated exactly. For the RNA secondary structure conformations, a new recursive formula incorporating the secondary structure and end-to-end distribution has been derived. Using the model, we investigate the extension-force curves, contact and population distributions and re-entering phenomena, respectively. we find that the force stretching homogeneous chains of hairpin and secondary structure conformations are very different: the unfolding of hairpins is two-state, while unfolding the latter is one-state. In addition, re-entering transitions only present in hairpin conformations, but are not observed in secondary structure conformations. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0212/0212268v1.pdf"}
{"id": "cond-mat0212551", "abstract": "  We investigate the nature of the low-energy, large-scale excitations in the three-dimensional Edwards-Anderson Ising spin glass with Gaussian couplings and free boundary conditions, by studying the response of the ground state to a coupling-dependent perturbation introduced previously. The ground states are determined exactly for system sizes up to 12^3 spins using a branch and cut algorithm. The data are consistent with a picture where the surface of the excitations is not space-filling, such as the droplet or the “TNT” picture, with only minimal corrections to scaling. When allowing for very large corrections to scaling, the data are also consistent with a picture with space-filling surfaces, such as replica symmetry breaking. The energy of the excitations scales with their size with a small exponent θ', which is compatible with zero if we allow moderate corrections to scaling. We compare the results with data for periodic boundary conditions obtained with a genetic algorithm, and discuss the effects of different boundary conditions on corrections to scaling. Finally, we analyze the performance of our branch and cut algorithm, finding that it is correlated with the existence of large-scale,low-energy excitations. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0212/0212551v2.pdf"}
{"id": "cond-mat0301443", "abstract": "  Epitaxy of oxide materials on silicon (Si) substrates is of great interest for future functional devices using the large variety of physical properties of the oxides as ferroelectricity, ferromagnetism, or superconductivity. Recently, materials with high spin polarization of the charge carriers have become interesting for semiconductor-oxide hybrid devices in spin electronics. Here, we report on pulsed laser deposition of magnetite (Fe3O4) on Si(001) substrates cleaned by an in situ laser beam high temperature treatment. After depositing a double buffer layer of titanium nitride (TiN) and magnesium oxide (MgO), a high quality epitaxial magnetite layer can be grown as verified by RHEED intensity oscillations and high resolution x-ray diffraction. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0301/0301443v4.pdf"}
{"id": "cond-mat0302104", "abstract": "  We discuss real-space lattice models equivalent to gauge theories with a discrete non-Abelian gauge group. We construct the Hamiltonian formalism which is appropriate for their solid-state physics implementation and outline their basic properties. The unusual physics of these systems is due to local constraints on the degrees of freedom which are variables localized on the links of the lattice. We discuss two types of constraints that become equivalent after a duality transformation for Abelian theories but are qualitatively different for non-Abelian ones. We emphasize highly nontrivial topological properties of the excitations (fluxons and charges) in these non-Abelian discrete lattice gauge theories. We show that an implementation of these models may provide one with the realization of an ideal quantum computer, that is the computer that is protected from the noise and allows a full set of precise manipulations required for quantum computations. We suggest a few designs of the Josephson-junction arrays that provide the experimental implementations of these models and discuss the physical restrictions on the parameters of their junctions. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0302/0302104v2.pdf"}
{"id": "cond-mat0302182", "abstract": "  A possible mechanism for the removal of the orbital degeneracy in RTiO3 (where R=La, Y, ...) is considered. The calculation is based on the Kugel-Khomskii Hamiltonian for electrons residing in the t2g orbitals of the Ti ions, and uses a self-consistent pe rturbation expansion in the interaction between the orbital and the spin degrees of freedom. The latter are assumed to be ordered in a Neel state, brought about by delicate interactions that are not included in the Kugel-Khomskii Hamiltonian. Within our model calculations, each of the t2g bands is found to acquire a finite, temperature-dependent dispersion, that lifts the orbital degeneracy. The orbital excitations are found to be heavily damped over a rather wide band. Consequently, they do not participate as a separate branch of excitations in the low-temperature thermodynamics.e ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0302/0302182v1.pdf"}
{"id": "cond-mat0303122", "abstract": "  We establish the quasi-one-dimensional Li purple bronze as a photoemission paradigm of Luttinger liquid behavior. We also show that generalized signatures of electron fractionalization are present in the angle resolved photoemission spectra for quasi-two-dimensional purple bronzes and certain cuprates. An important component of our analysis for the quasi-two-dimensional systems is the proposal of a “melted holon” scenario for the k-independent background that accompanies but does not interact with the peaks that disperse to define the Fermi surface. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0303/0303122v1.pdf"}
{"id": "cond-mat0303248", "abstract": "  The charging of a quantum box, coupled to a lead by tunneling through a single resonant level, is studied near the degeneracy points of the Coulomb blockade. Combining Wilson's numerical renormalization-group method with perturbative scaling approaches, the corresponding low-energy Hamiltonian is solved for arbitrary temperatures, gate voltages, tunneling rates, and energies of the impurity level. Similar to the case of a weak tunnel barrier, the shape of the charge step is governed at low temperatures by the non-Fermi-liquid fixed point of the two-channel Kondo effect. However, the associated Kondo temperature TK is strongly modified. Most notably, TK is proportional to the width of the level if the transmission through the impurity is close to unity at the Fermi energy, and is no longer exponentially small in one over the tunneling matrix element. Focusing on a particle-hole symmetric level, the two-channel Kondo effect is found to be robust against the inclusion of an on-site repulsion on the level. For a large on-site repulsion and a large asymmetry in the tunneling rates to box and to the lead, there is a sequence of Kondo effects: first the local magnetic moment that forms on the level undergoes single-channel screening, followed by two-channel overscreening of the charge fluctuations inside the box. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0303/0303248v1.pdf"}
{"id": "cond-mat0303394", "abstract": "  A coherent superposition of many nuclear spin states can be prepared and manipulated via the hyperfine interaction with the electronic spins by varying the Landau level filling factor through the gate voltage in appropriately designed Quantum Hall Ferromagnet. During the manipulation periods the 2D electron system forms spatially large Skyrmionic spin textures, where many nuclear spins follow locally the electron spin polarization. It is shown that the collective spin rotation of a single spin texture is gapless in the limit of zero Zeeman splitting, and may dominate the nuclear spins relaxation and decoherence processes in the quantum well. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0303/0303394v1.pdf"}
{"id": "cond-mat0304129", "abstract": "  We study a one-dimensional system that consists of an electron gas coupled to a spin-1/2 chain by Kondo interaction away from half-filling. We show that zero-temperature transitions between phases with \"small\" and \"large\" Fermi momenta can be continuous. Such a continuous but Fermi-momentum-changing transition arises in the presence of spin anisotropy, from a Luttinger liquid with a small Fermi momentum to a Kondo-dimer phase with a large Fermi momentum. We have also added a frustrating next-nearest-neighbor interaction in the spin chain to show the possibility of a similar Fermi-momentum-changing transition, between the Kondo phase and a spin-Peierls phase, in the spin isotropic case. This transition, however, appears to involve a region in which the two phases coexist. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0304/0304129v3.pdf"}
{"id": "cond-mat0304440", "abstract": "  We resolve the problem of the violation of single parameter scaling at the zero energy of the Anderson tight-binding model with diagonal disorder. It follows from the symmetry properties of the tight-binding Hamiltonian that this spectral point is in fact a boundary between two adjacent bands. The states in the vicinity of this energy behave similarly to states at other band boundaries, which are known to violate single parameter scaling. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0304/0304440v2.pdf"}
{"id": "cond-mat0305359", "abstract": "  A lattice model of 3He - 4He mixtures which takes into account the continuous rotational symmetry O(2) of the superfluid degrees of freedom of 4He is studied in the molecular-field approximation and by Monte Carlo simulations in three dimensions. In contrast to its two-dimensional version, for reasonable values of the interaction parameters the resulting phase diagram resembles that observed experimentally for 3He - 4He mixtures, for which phase separation occurs as a consequence of the superfluid transition. The corresponding continuum Ginzburg-Landau model with two order parameters describing 3He- 4He mixtures near tricriticality is derived from the considered lattice model. All coupling constants appearing in the continuum model are explicitly expressed in terms of the mean concentration of 4He, the temperature, and the microscopic interaction parameters characterizing the lattice system. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0305/0305359v1.pdf"}
{"id": "cond-mat0305667", "abstract": "  A fractional reaction-diffusion equation is derived from a continuous time random walk model when the transport is dispersive. The exit from the encounter distance, which is described by the algebraic waiting time distribution of jump motion, interferes with the reaction at the encounter distance. Therefore, the reaction term has a memory effect. The derived equation is applied to the geminate recombination problem. The recombination is shown to depend on the intrinsic reaction rate, in contrast with the results of Sung et al. [J. Chem. Phys. 116, 2338 (2002)], which were obtained from the fractional reaction-diffusion equation where the diffusion term has a memory effect but the reaction term does not. The reactivity dependence of the recombination probability is confirmed by numerical simulations. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0305/0305667v1.pdf"}
{"id": "cond-mat0308053", "abstract": "  We introduce a spectral density functional theory which can be used to compute energetics and spectra of real strongly–correlated materials using methods, algorithms and computer programs of the electronic structure theory of solids. The approach considers the total free energy of a system as a functional of a local electronic Green function which is probed in the region of interest. Since we have a variety of notions of locality in our formulation, our method is manifestly basis–set dependent. However, it produces the exact total energy and local excitational spectrum provided that the exact functional is extremized. The self–energy of the theory appears as an auxiliary mass operator similar to the introduction of the ground–state Kohn–Sham potential in density functional theory. It is automatically short–ranged in the same region of Hilbert space which defines the local Green function. We exploit this property to find good approximations to the functional. For example, if electronic self–energy is known to be local in some portion of Hilbert space, a good approximation to the functional is provided by the corresponding local dynamical mean–field theory. A simplified implementation of the theory is described based on the linear muffin–tin orbital method widely used in electronic strucure calculations. We demonstrate the power of the approach on the long–standing problem of the anomalous volume expansion of metallic plutonium. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0308/0308053v1.pdf"}
{"id": "cond-mat0308542", "abstract": "  We study the diffusion process in a Heisenberg chain with correlated spatial disorder, with a power spectrum in the momentum space behaving as k^-β, using a stochastic description. It establishes a direct connection between the fluctuation in the spin-wave density of states and the noise density of states. For continuous ranges of the exponent β, we find superdiffusive and ballistic spin-wave motions. Both diffusion exponents predicted by the stochastic procedure agree with the ones calculated using the Hamiltonian dynamics. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0308/0308542v3.pdf"}
{"id": "cond-mat0309057", "abstract": "  A new density matrix renormalisation group (DMRG) approach is presented for quantum systems of two spatial dimensions. In particular, it is shown that it is possible to create a multi-chain-type 2D DMRG approach which utilises previously determined system and environment blocks at all points. One firstly builds up effective quasi-1D system and environment blocks of width L and these quasi-1D blocks are then used to as the initial building-blocks of a new 2D infinite-lattice algorithm. This algorithm is found to be competitive with those results of previous 2D DMRG algorithms and also of the best of other approximate methods. An illustration of this is given for the spin-half and spin-one Heisenberg models on the square lattice. The best results for the ground-state energies per bond of the spin-half and spin-one square-lattice Heisenberg antiferromagnets for the N = 20 × 20 lattice using this treatment are given by E_g/N_B = -0.3321 and E_g/N_B = -1.1525, respectively. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0309/0309057v1.pdf"}
{"id": "cond-mat0310095", "abstract": "  The interface stability against small perturbations of the planar solid-liquid interface is considered analytically in linear approximation. Following the analytical procedure of Trivedi and Kurz (Trivedi R, Kurz W. Acta Metall 1986;34:1663), which is advancing the original treatment of morphological stability by Mullins and Sekerka (Mullins WW, Sekerka RF. J Appl Phys 1964;35:444) to the case of rapid solidification, we extend the model by introducing the local nonequilibrium in the solute diffusion field around the interface. A solution to the heat- and mass-transport problem around the perturbed interface is given in the presence of the local nonequilibrium solute diffusion. Using the developing local nonequilibrium model of solidification, the self-consistent analysis of linear morphological stability is presented with the attribution to the marginal (neutral) and absolute morphological stability of a rapidly moving interface. Special consideration of the interface stability for the cases of solidification in negative and positive thermal gradients is given. A quantitative comparison of the model predictions for the absolute morphological stability is presented with regard to experimental results of Hoglund and Aziz (Hoglund DE, Aziz MJ. Mat Res Soc Symp Proc 1992;205:325) on critical solute concentration for the interface breakdown during rapid solidification of Si–Sn alloys. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0310/0310095v1.pdf"}
{"id": "cond-mat0310325", "abstract": "  We perform density functional theory calculations on a series of armchair and zigzag nanotubes of diameters less than 1nm using the all-electron Full-Potential(-Linearised)-Augmented-Plane-Wave (FPLAPW) method. Emphasis is laid on the effects of curvature, the electron beam orientation and the inclusion of the core-hole on the carbon electron energy loss K-edge. The electron energy loss near-edge spectra of all the studied tubes show strong curvature effects compared to that of flat graphene. The curvature induced π-σ hybridisation is shown to have a more drastic effect on the electronic properties of zigzag tubes than on those of armchair tubes. We show that the core-hole effect must be accounted for in order to correctly reproduce electron energy loss measurements. We also find that, the energy loss near edge spectra of these carbon systems are dominantly dipole selected and that they can be expressed simply as a proportionality with the local momentum projected density of states, thus portraying the weak energy dependence of the transition matrix elements. Compared to graphite, the ELNES of carbon nanotubes show a reduced anisotropy. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0310/0310325v1.pdf"}
{"id": "cond-mat0310585", "abstract": "  We study the time evolution of two ecosystems in the presence of external noise and climatic periodical forcing by a generalized Lotka-Volterra (LV) model. In the first ecosystem, composed by two competing species, we find noise induced phenomena such as: (i) quasi deterministic oscillations, (ii) stochastic resonance, (iii) noise delayed extinction and (iv) spatial patterns. In the second ecosystem, composed by three interacting species (one predator and two preys), using a discrete model of the LV equations we find that the time evolution of the spatial patterns is strongly dependent on the initial conditions of the three species. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0310/0310585v2.pdf"}
{"id": "cond-mat0311602", "abstract": "  We present a model for the ion distribution near a charged surface, based on the response of the ions to the presence of a single test particle. Near an infinite planar surface this model produces the exact density profile in the limits of weak and strong coupling, which correspond to zero and infinite values of the dimensionless coupling parameter. At intermediate values of the coupling parameter our approach leads to approximate density profiles that agree qualitatively with Monte-Carlo simulation. For large values of the coupling parameter our model predicts a crossover from exponential to algebraic decay at large distance from the charged plate. Based on the test charge approach we argue that the exact density profile is described, in this regime, by a modified mean field equation, which takes into account the interaction of an ion with the ions close to the charged plate. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0311/0311602v2.pdf"}
{"id": "cond-mat0311642", "abstract": "  In this paper the superheating of electron plasma by femtosecond laser pulses is investigated. With Heaviside thermal equation (Lasers in Engineering, 12, (2002), p.17) the generation of superhot electrons is described. It is shown that in hot electron plasma (i.e. with electron energies >5MeV) the thermal shock waves can be generated. Key words: Femtosecond laser pulses; Hot electron plasma; Shock thermal waves. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0311/0311642v1.pdf"}
{"id": "cond-mat0312131", "abstract": "  We derive the mean-field equations characterizing the dynamics of a rumor process that takes place on top of complex heterogeneous networks. These equations are solved numerically by means of a stochastic approach. First, we present analytical and Monte Carlo calculations for homogeneous networks and compare the results with those obtained by the numerical method. Then, we study the spreading process in detail for random scale-free networks. The time profiles for several quantities are numerically computed, which allow us to distinguish among different variants of rumor spreading algorithms. Our conclusions are directed to possible applications in replicated database maintenance, peer to peer communication networks and social spreading phenomena. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0312/0312131v2.pdf"}
{"id": "cond-mat0312140", "abstract": "  Using a lattice-gas model with pairwise interactions, we study the ordered structures, coverage dependence of the heat of adsorption, and other experimentally observable behavior of adsorbed CO overlayers on Pd(100) single crystal surfaces. Transfer matrix and Monte Carlo methods give accurate information regarding the lattice-gas model that often contradicts simple mean-field-like analysis. We demonstrate the usefulness of the model by reproducing experimental results over a large range of pressures and temperatures. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0312/0312140v1.pdf"}
{"id": "cond-mat0401061", "abstract": "  There are three levels of description in classical statistical mechanics, the microscopic/dynamic, the macroscopic/statistical and the thermodynamic. At one end there is a well-used concept of equilibrium in thermodynamics and at the other dynamic equilibrium does not exist in measure-preserving reversible dynamic systems. Statistical mechanics attempts to situate equilibrium at the macroscopic level in the Boltzmann approach and at the statistical level in the Gibbs approach. The aim of this work is to propose a reconciliation between these approaches and to do so we need to reconsider the concept of equilibrium. Our proposal is that the binary property of the system being or not being in equilibrium is replaced by a continuous property of commonness. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0401/0401061v2.pdf"}
{"id": "cond-mat0401070", "abstract": "  There are several ways to create the vorticity-free solitary waves – rarefaction pulses – in condensates: by the process of strongly nonequilibrium condensate formation in a weakly interacting Bose gas, by creating local depletion of the condensate density by a laser beam, and by moving a small object with supercritical velocities. Perturbations created by such waves colliding with vortices are studied in the context of the Gross-Pitaevskii model. We find that the effect of the interactions consists of two competing mechanisms: the creation of vortex line as rarefaction waves acquire circulation in a vicinity of a vortex core and the loss of the vortex line to sound due to Kelvin waves that are generated on vortex lines by rarefaction pulses. When a vortex ring collides with a rarefaction wave, the ring either stabilises to a smaller ring after emitting sound through Kelvin wave radiation or the entire energy of the vortex ring is lost to sound if the radius of the ring is of the order of the healing length. We show that during the time evolution of a tangle of vortices, the interactions with rarefaction pulses provide an important dissipation mechanism enhancing the decay of superfluid turbulence. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0401/0401070v2.pdf"}
{"id": "cond-mat0403204", "abstract": "  We revisit the expression for the conductance of a general nanostructure – such as a quantum point contact – as obtained from the linear response theory. We show that the conductance represents the strength of the Drude singularity in the conductivity σ(k,k';iω→ 0). Using the equation of continuity for electric charge we obtain a formula for conductance in terms of polarization of the system. This identification can be used for direct calculation of the conductance for systems of interest even at the ab-initio level. In particular, we show that one can evaluate the conductance from calculations for a finite system without the need for special “transport” boundary conditions. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0403/0403204v1.pdf"}
{"id": "cond-mat0404544", "abstract": "  The Bloch oscillating transistor (BOT) is a device, where single electron current through a normal tunnel junction can be used to enhance Cooper pair current in a mesoscopic Josephson junction leading to signal amplification. In this paper we develop a theory, where the BOT dynamics is described as a two-level system. The theory is used to predict current-voltage characteristics and small-signal response. Transition from stable operation into hysteretic regime is studied. By identifying the two-level switching noise as the main source of fluctuations, the expressions for equivalent noise sources and the noise temperature are derived. The validity of the model is tested by comparing the results with simulations. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0404/0404544v1.pdf"}
{"id": "cond-mat0405237", "abstract": "  In this paper we discuss the implication of the existence of a sliding symmetry, equivalent to the absence of a shear modulus, on the low-energy theory of the quantum hall smectic (QHS) state. We show, through renormalization group calculations, that such a symmetry causes the naive continuum approximation in the direction perpendicular to the stripes to break down through infrared divergent contributions originating from naively irrelevant operators. In particular, we show that the correct fixed point has the form of an array of sliding Luttinger liquids which is free from superficially \"irrelevant operators\". Similar considerations apply to all theories with sliding symmetries. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0405/0405237v1.pdf"}
{"id": "cond-mat0405568", "abstract": "  We report two examples of transport phenomena based on sharp features in the effective density of states of molecular-scale transistors: Kondo physics in C_60-based devices, and gate-modulated negative differential resistance (NDR) in “control” devices that we ascribe to adsorbed contamination. We discuss the need for a statistical approach to device characterization, and the criteria that must be satisfied to infer that transport is based on single molecules. We describe apparent Kondo physics in C_60-based single-molecule transistors (SMTs), including signatures of molecular vibrations in the Kondo regime. Finally, we report gate-modulated NDR in devices made without intentional molecular components, and discuss possible origins of this property. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0405/0405568v1.pdf"}
{"id": "cond-mat0405585", "abstract": "  The generalization of the dimer model on a two-leg ladder is defined and investigated both, analytically and numerically. For the closed system we calculate the Landauer resistance analytically and found the presence of the point of delocalization at the band center which is confirmed by the numerical calculations of the Lyapunov exponent. We calculate also analytically the localization length index and present the numerical investigations of the density of states (DOS). For the open counterpart of this model the distribution of the Wigner delay times is calculated numerically. It is shown how the localization-delocalization transition manifest itself in the behavior of the distribution. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0405/0405585v2.pdf"}
{"id": "cond-mat0405615", "abstract": "  Using the recently developed version of the GW method employing the one-site approximation and self-consistent quasiparticle basis set we calculated the electronic structure of 3d and 4d transition metals at experimental atomic volumes. The results are compared with traditional local density approach and with experimental XPS and BIS spectra. Our results indicate that this technique can be used as a practical starting point for more sophisticated many-body studies of realistic electronic structures. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0405/0405615v1.pdf"}
{"id": "cond-mat0406225", "abstract": "  Properties of low-variability periods in the time series are analysed. The theoretical approach is used to show the relationship between the multi-scaling of low-variability periods and multi-affinity of the time series. It is shown that this technically simple method is capable of reveling more details about time-series than the traditional multi-affine analysis. We have applied this scaling analysis to financial time series: a number of daily currency and stock index time series. The results show a good scaling behaviour for different model parameters. The analysis of high-frequency USD-EUR exchange rate data confirmed the theoretical expectations. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0406/0406225v2.pdf"}
{"id": "cond-mat0406482", "abstract": "  We have produced magnetic patterns suitable for trapping and manipulating neutral atoms on a 1 μm length scale. The required patterns are made in Co/Pt thin films on a silicon substrate, using the heat from a focussed laser beam to induce controlled domain reversal. In this way we draw lines and \"paint\" shaped areas of reversed magnetization with sub-micron resolution. These structures produce magnetic microtraps above the surface that are suitable for holding rubidium atoms with trap frequencies as high as  1 MHz. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0406/0406482v1.pdf"}
{"id": "cond-mat0407213", "abstract": "  A survey of acoustic devices for focusing airborne sound is presented. We introduce a new approach to design high quality acoustic lenses based on arrays of cylindrical rigid scatterers in air. A population based stochastic search algorithm is used in conjunction with the multiple scattering theory to optimize a cluster of cylinders that focuses the sound in a prefixed focal point. Various lenses of different sized clusters, for different frequencies and with different focal lengths are presented. In general three focusing phenomena are remarked, focusing due to refraction, diffraction and focusing due to multiple scattering. The dependency on the frequency of the incident sound and the focal distance is analyzed indicating that higher frequencies and smaller focal distances favour larger amplifications in thin lenses based on multiple scattering. Furthermore, the robustness of a designed acoustic lens is studied, examining the focusing effect against errors in the cylinders' positions and their radius. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0407/0407213v1.pdf"}
{"id": "cond-mat0407757", "abstract": "  Plug conveying along a vertical tube has been investigated through simulation, using a discrete element simulation approach for the granulate particles and a pressure field approach for the gas. The result is compared with an experiment. The dynamics of a plug are described by porosity, velocity and force profiles. Their dependence on simulation parameters provides an overall picture of plug conveying. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0407/0407757v2.pdf"}
{"id": "cond-mat0407773", "abstract": "  We show how a simple laboratory experiment can illustrate certain electrical transport properties of metallic granular media. At a low critical imposed voltage, a transition from an insulating to a conductive state is observed. This transition comes from an electro-thermal coupling in the vicinity of the microcontacts between grains where microwelding occurs. Our apparatus allows us to obtain an implicit determination of the microcontact temperature, which is analogous to the use of a resistive thermometer. The experiment also illustrates an old problem, the explanation of Branly's coherer effect - a radio wave detector used for the first wireless radio transmission, and based on the sensitivity of the metal fillings conductivity to an electromagnetic wave. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0407/0407773v2.pdf"}
{"id": "cond-mat0408219", "abstract": "  We investigate the long-time behavior of a majority rule opinion dynamics model in finite spatial dimensions. Each site of the system is endowed with a two-state spin variable that evolves by majority rule. In a single update event, a group of spins with a fixed (odd) size is specified and all members of the group adopt the local majority state. Repeated application of this update step leads to a coarsening mosaic of spin domains and ultimate consensus in a finite system. The approach to consensus is governed by two disparate time scales, with the longer time scale arising from realizations in which spins organize into coherent single-opinion bands. The consequences of this geometrical organization on the long-time kinetics are explored. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0408/0408219v2.pdf"}
{"id": "cond-mat0409469", "abstract": "  We investigate the competition between antiferromagnetism and triplet superconductivity in quasi one-dimensional electron systems. We show that the two order parameters can be unified using a SO(4) symmetry and demonstrate the existence of such symmetry in one dimensional Luttinger liquids of interacting electrons. We argue that approximate SO(4) symmetry remains valid even when interchain hopping is strong enough to turn the system into a strongly anisotropic Fermi liquid. For unitary triplet superconductors SO(4) symmetry requires a first order transition between antiferromagnetic and superconducting phases. Analysis of thermal fluctuations shows that the transition between the normal and the superconducting phases is weakly first order, and the normal to antiferromagnet phase boundary has a tricritical point, with the transition being first order in the vicinity of the superconducting phase. We propose that this phase diagram explains coexistence regions between the superconducting and the antiferromagnetic phases, and between the antiferromagnetic and the normal phases observed in (TMTSF)_2PF_6. For non-unitary triplet superconductors the SO(4) symmetry predicts the existence of a mixed phase of antiferromagnetism and superconductivity. We discuss experimental tests of the SO(4) symmetry in neutron scattering and tunneling experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0409/0409469v1.pdf"}
{"id": "cond-mat0410677", "abstract": "  We present a theoretical treatment of the surprisingly large damping observed recently in one-dimensional Bose-Einstein atomic condensates in optical lattices. We show that time-dependent Hartree-Fock-Bogoliubov (HFB) calculations can describe qualitatively the main features of the damping observed over a range of lattice depths. We also derive a formula of the fluctuation-dissipation type for the damping, based on a picture in which the coherent motion of the condensate atoms is disrupted as they try to flow through the random local potential created by the irregular motion of noncondensate atoms. We expect this irregular motion to result from the well-known dynamical instability exhibited by the mean-field theory for these systems. When parameters for the characteristic strength and correlation times of the fluctuations, obtained from the HFB calculations, are substituted in the damping formula, we find very good agreement with the experimentally-observed damping, as long as the lattice is shallow enough for the fraction of atoms in the Mott insulator phase to be negligible. We also include, for completeness, the results of other calculations based on the Gutzwiller ansatz, which appear to work better for the deeper lattices. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0410/0410677v4.pdf"}
{"id": "cond-mat0410730", "abstract": "  We present a readout method for superconducting flux qubits. The qubit quantum flux state can be measured by determining the Josephson inductance of an inductively coupled DC superconducting quantum interference device (DC-SQUID). We determine the response function of the DC-SQUID and its back-action on the qubit during measurement. Due to driving, the qubit energy relaxation rate depends on the spectral density of the measurement circuit noise at sum and difference frequencies of the qubit Larmor frequency and SQUID driving frequency. The qubit dephasing rate is proportional to the spectral density of circuit noise at the SQUID driving frequency. These features of the backaction are qualitatively different from the case when the SQUID is used in the usual switching mode. For a particular type of readout circuit with feasible parameters we find that single shot readout of a superconducting flux qubit is possible. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0410/0410730v1.pdf"}
{"id": "cond-mat0411192", "abstract": "  We study the influence of structural lattice fluctuations on the elastic electron transport in single-wall carbon nanotubes within a density-functional-based scheme. In the linear response regime, the linear conductance is calculated via configurational averages over the distorted lattice. Results obtained from a frozen-phonon approach as well as from molecular dynamics simulations are compared. We further suggest that the effect of structural fluctuations can be qualitatively captured by the Anderson model with bond disorder. The influence of individual vibrational modes on the electronic transport is discussed as well as the role of zero-point fluctuations. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0411/0411192v2.pdf"}
{"id": "cond-mat0412363", "abstract": "  The surface stress can have important effects on the elastic properties of nano-sized structures. Here we analyze the effect of surface stress on Mode-3 crack displacement and stress-field solutions under the assumption of linear elasticity. We show that surface effects generate non-K terms near the crack-tip. We also find the effect of such terms on the conventional small-scale yielding assumption. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0412/0412363v1.pdf"}
{"id": "cond-mat0412493", "abstract": "  We show that active transport processes in biological systems can be understood through a local equilibrium description formulated at the mesoscale, the scale to describe stochastic processes. This new approach uses the method established by nonequilibrium thermodynamics to account for the irreversible processes occurring at this scale and provides nonlinear kinetic equations for the rates in terms of the driving forces. The results show that the application domain of nonequilibrium thermodynamics method to biological systems goes beyond the linear domain. A model for transport of Ca^2+ by the Ca^2+-ATPase, coupled to the hydrolysis of adenosine-triphosphate is analyzed in detail showing that it depends on the reaction Gibbs energy in a non-linear way. Our results unify thermodynamic and kinetic descriptions, thereby opening new perspectives in the study of different transport phenomena in biological systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0412/0412493v1.pdf"}
{"id": "cond-mat0412562", "abstract": "  Electron transfer (ET) across molecular chains including an impurity is studied based on a recently improved real-time path integral Monte Carlo (PIMC) approach [J. Chem. Phys. 121, 12696 (2004)]. The reduced electronic dynamics is studied for various bridge lengths and defect site energies. By determining intersite hopping rates from PIMC simulations up to moderate times, the relaxation process in the extreme long time limit is captured within a sequential transfer model. The total transfer rate is extracted and shown to be enhanced for certain defect site energies. Further, it is revealed that the entire bridge compound approaches a steady state on a much shorter time scale than that related to the total transfer which allows for a simplified description of ET along donor-bridge-acceptor systems in the long time range. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0412/0412562v1.pdf"}
{"id": "cond-mat0412592", "abstract": "  We present a density-matrix rate-equation approach to sequential tunneling through a metal particle weakly coupled to ferromagnetic leads. The density-matrix description is able to deal with correlations between degenerate many-electron states that the standard rate equation formalism in terms of occupation probabilities cannot describe. Our formalism is valid for an arbitrary number of electrons on the dot, for an arbitrary angle between the polarization directions of the leads, and with or without spin-orbit scattering on the metal particle. Interestingly, we find that the density-matrix description may be necessary even for metal particles with unpolarized leads if three or more single-electron levels contribute to the transport current and electron-electron interactions in the metal particle are described by the `universal interaction Hamiltonian'. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0412/0412592v1.pdf"}
{"id": "cond-mat0412596", "abstract": "  We investigated the role that the electron-electron interaction plays on the propagating properties of wave packets in a one-dimensional crystal with impurities. We considered two interacting particles with opposite spins in a band, where we treated their interaction along the Hubbard model. We have obtained the density of states of the crystal for different values of the interaction term, as well as solved the dynamical Schrödinger equation by varying the initial conditions. We have introduced a method through which we were able to follow the time evolution of the wave packets for both spins showed in three-dimensional plots, and have evaluated, for each particle, the corresponding MSD^'s and the centroids as function of time . These measurements allow us to determine the influence of the interaction on dynamical properties. We discussed the combined effect that the extension of the initial wave packets and the interaction strength have on propagating properties. Under certain conditions we obtained an entanglement of the two packets associated with both spins that takes place in a small region of the lattice. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0412/0412596v1.pdf"}
{"id": "cond-mat0501066", "abstract": "  We study the adsorption of homogeneous or heterogeneous polymers onto heterogeneous planar surfaces with exponentially decaying site-site correlations, using a variational reference system approach. As a main result, we derive simple equations for the adsorption-desorption transition line. We show that the adsorption threshold is the same for systems with quenched and annealed disorder. The results are discussed with respect to their implications for the physics of molecular recognition. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0501/0501066v1.pdf"}
{"id": "cond-mat0501335", "abstract": "  We introduce a technique to filter out complex data-sets by extracting a subgraph of representative links. Such a filtering can be tuned up to any desired level by controlling the genus of the resulting graph. We show that this technique is especially suitable for correlation based graphs giving filtered graphs which preserve the hierarchical organization of the minimum spanning tree but containing a larger amount of information in their internal structure. In particular in the case of planar filtered graphs (genus equal to 0) triangular loops and 4 element cliques are formed. The application of this filtering procedure to 100 stocks in the USA equity markets shows that such loops and cliques have important and significant relations with the market structure and properties. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0501/0501335v2.pdf"}
{"id": "cond-mat0501409", "abstract": "  We propose a simple model of a waveguide network designed following the growth rule of a Vicsek fractal. We show, within the framework of real space renormalization group (RSRG) method, that such a design may lead to the appearance of unusual electromagnetic modes. Such modes exhibit an extended character in RSRG sense. However, they lead to a power law decay in the end-to-end transmission of light across such a network model as the size of the network increases. This, to our mind, may lead to an observation of power law localization of light in a fractal waveguide network. The general occurence of photonic band gaps and their change as a function of the parameters of the system are also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0501/0501409v2.pdf"}
{"id": "cond-mat0505087", "abstract": "  We present new results for the properties of phases and phase transitions in spin-triplet ferromagnetic superconductors. The superconductivity of the mixed phase of coexistence of ferromagnetism and unconventional superconductivity is triggered by the presence of spontaneous magnetization. The mixed phase is stable but the other superconducting phases that usually exist in unconventional superconductors are either unstable or for particular values of the parameters of the theory some of them are metastable at relatively low temperatures in a quite narrow domain of the phase diagram. Phase transitions from the normal phase to the phase of coexistence is of first order while the phase transition from the ferromagnetic phase to the coexistence phase can be either of first or second order depending on the concrete substance. Cooper pair and crystal anisotropies determine a more precise outline of the phase diagram shape and reduce the degeneration of ground states of the system but they do not change drastically phase stability domains and thermodynamic properties of the respective phases. The results are discussed in view of application to metallic ferromagnets as UGe2, ZrZn2, URhGe. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0505/0505087v1.pdf"}
{"id": "cond-mat0506144", "abstract": "  It is shown how the static and dynamic electromagnetic properties can be calculated for thin flat superconducting films of any shape and size, also multiply connected as used for SQUIDs, and for any value of the effective magnetic London penetration depth Lambda. As examples, the distributions of sheet current and magnetic field are obtained for rectangular and circular films without and with slits and holes, in response to an applied perpendicular magnetic field and to magnetic vortices moving in the film. The self energy and interaction of vortices with each other and with an applied magnetic field and/or transport current are given. Due to the long ranging magnetic stray field, these energies depend on the size and shape of the film and on the vortex position even in large films, in contrast to the situation in large bulk superconductors. The focussing of magnetic flux into the central hole of square films without and with a radial slit is compared. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0506/0506144v1.pdf"}
{"id": "cond-mat0506272", "abstract": "  We solve the two-particle s-wave scattering problem for ultracold atom gases confined in arbitrary quasi-one-dimensional trapping potentials, allowing for two different atom species. As a consequence, the center-of-mass and relative degrees of freedom do not factorize. We derive bound-state solutions and obtain the general scattering solution, which exhibits several resonances in the 1D scattering length induced by the confinement. We apply our formalism to two experimentally relevant cases: (i) interspecies scattering in a two-species mixture, and (ii) the two-body problem for a single species in a non-parabolic trap. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0506/0506272v1.pdf"}
{"id": "cond-mat0507195", "abstract": "  We present a real-space renormalization group approach for the corner Hamiltonian, which is relevant to the reduced density matrix in the density matrix renormalization group. A set of self-consistent equations that the renormalized Hamiltonian should satisfy in the thermodynamic limit is also derived from the fixed point of the recursion relation for the corner Hamiltonian. We demonstrate the renormalization group algorithm for the S=1/2 XXZ spin chain and show that the results are consistent with the exact solution. We further examine the renormalization group for the S=1 Heisenberg spin chain and then discuss the nature of the eigenvalue spectrum of the corner Hamiltonian for the non-integrable model. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0507/0507195v3.pdf"}
{"id": "cond-mat0507381", "abstract": "  We present new data for the electrical conductivity of foams in which the liquid fraction ranges from two to eighty percent. We compare with a comprehensive collection of prior data, and we model all results with simple empirical formulæ. We achieve a unified description that applies equally to dry foams and emulsions, where the droplets are highly compressed, as well as to dilute suspensions of spherical particles, where the particle separation is large. In the former limit, Lemlich's result is recovered; in the latter limit, Maxwell's result is recovered. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0507/0507381v1.pdf"}
{"id": "cond-mat0509318", "abstract": "  Superconducting single-flux-quantum (SFQ) circuits have so far been developed and optimized for operation at or above helium temperatures. The SFQ approach, however, should also provide potentially viable and scalable control and read-out circuits for Josephson-junction qubits and other applications with much lower, milli-kelvin, operating temperatures. This paper analyzes the overheating problem which becomes important in this new temperature range. We suggest a thermal model of the SFQ circuits at sub-kelvin temperatures and present experimental results on overheating of electrons and silicon substrate which support this model. The model establishes quantitative limitations on the dissipated power both for \"local\" electron overheating in resistors and \"global\" overheating due to ballistic phonon propagation along the substrate. Possible changes in the thermal design of SFQ circuits in view of the overheating problem are also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0509/0509318v1.pdf"}
{"id": "cond-mat0509493", "abstract": "  The dynamics of a tracer particle in a stationary driven granular gas is investigated. We show how to transform the linear Boltzmann equation describing the dynamics of the tracer into a master equation for a continuous Markov process. The transition rates depend upon the stationary velocity distribution of the gas. When the gas has a Gaussian velocity probability distribution function (pdf), the stationary velocity pdf of the tracer is Gaussian with a lower temperature and satisfies detailed balance for any value of the restitution coefficient α. As soon as the velocity pdf of the gas departs from the Gaussian form, detailed balance is violated. This non-equilibrium state can be characterized in terms of a Lebowitz-Spohn action functional W(τ) defined over trajectories of time duration τ. We discuss the properties of this functional and of a similar functional W̅(τ) which differs from the first for a term which is non-extensive in time. On the one hand we show that in numerical experiments, i.e. at finite times τ, the two functionals have different fluctuations and W̅ always satisfies an Evans-Searles-like symmetry. On the other hand we cannot observe the verification of the Lebowitz-Spohn-Gallavotti-Cohen (LS-GC) relation, which is expected for W(τ) at very large times τ. We give an argument for the possible failure of the LS-GC relation in this situation. We also suggest practical recipes for measuring W(τ) and W̅(τ) in experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0509/0509493v1.pdf"}
{"id": "cond-mat0509537", "abstract": "  The concept of network immunity, i.e., the robustness of the network connectivity after a random deletion of edges or vertices, has been investigated in biological or communication networks. We apply this concept to a self-assembling, physical network of microemulsion droplets connected by telechelic polymers, where more than one polymer can connect a pair of droplets. The gel phase of this system has higher immunity if it is more likely to survive (i.e., maintain a macroscopic, connected component) when some of the polymers are randomly degraded. We consider the distribution p(σ) of the number of polymers between a pair of droplets, and show that gel immunity decreases as the variance of p(σ) increases. Repulsive interactions between the polymers decrease the variance, while attractive interactions increase the variance, and may result in a bimodal p(σ). ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0509/0509537v3.pdf"}
{"id": "cond-mat0509564", "abstract": "  We investigate the dynamic scaling properties of stochastic particle systems on a non-deterministic scale-free network. It has been known that the dynamic scaling behavior depends on the degree distribution exponent of the underlying scale-free network. Our study shows that it also depends on the global structure of the underlying network. In random walks on the tree structure scale-free network, we find that the relaxation time follows a power-law scaling τ∼ N with the network size N. And the random walker return probability decays algebraically with the decay exponent which varies from node to node. On the other hand, in random walks on the looped scale-free network, they do not show the power-law scaling. We also study a pair-annihilation process on the scale-free network with the tree and the looped structure, respectively. We find that the particle density decays algebraically in time both cases, but with the different exponent. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0509/0509564v1.pdf"}
{"id": "cond-mat0509766", "abstract": "  We consider the signatures of the Integer Quantum Hall Effect in a degenerate gas of electrically neutral atomic fermions. An effective magnetic field is achieved by applying two incident light beams with a high orbital angular momentum. We show how states corresponding to completely filled Landau levels are obtained and discuss various possibilities to measure the incompressible nature of the trapped two-dimensional gas ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0509/0509766v2.pdf"}
{"id": "cond-mat0512120", "abstract": "  We show theoretically that finite two-dimensional (2D) photonic crystals in thin semiconductor membranes strongly modify the spontaneous emission rate of embedded dipole emitters. Three-dimensional Finite-Difference Time-Domain calculations show over 7 times inhibition and 15 times enhancement of the emission rate compared to the vacuum emission rate for judiciously oriented and positioned dipoles. The vertical index confinement in membranes strongly enhances modifications of the emission rate as compared to vertically unconfined 2D photonic crystals. The emission rate modifications inside the membrane mimic the local electric field mode density in a simple 2D model. The inhibition of emission saturates exponentially as the crystal size around the source is increased, with a 1/e length that is inversely proportional to the bandwidth of the emission gap. We obtain inhibition of emission only close to the slab center. However, enhancement of emission persists even outside the membrane, with a distance dependence which dependence can be understood by analyzing the contributions to the spontaneous emission rate of the different vertically guided modes of the membrane. Finally we show that the emission changes can even be observed in experiments with ensembles of randomly oriented dipoles, despite the contribution of dipoles for which no gap exists. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0512/0512120v1.pdf"}
{"id": "cond-mat0512125", "abstract": "  Computer simulations are used to generate two-dimensional diffusion-limited deposits of dipoles. The structure of these deposits is analyzed by measuring some global quantities: the density of the deposit and the lateral correlation function at a given height, the mean height of the upper surface for a given number of deposited particles and the interfacial width at a given height. Evidences are given that the fractal dimension of the deposits remains constant as the deposition proceeds, independently of the dipolar strength. These same deposits are used to obtain the growth probability measure through Monte Carlo techniques. It is found that the distribution of growth probabilities obeys multifractal scaling, i.e. it can be analyzed in terms of its f(α) multifractal spectrum. For low dipolar strengths, the f(α) spectrum is similar to that of diffusion-limited aggregation. Our results suggest that for increasing dipolar strength both the minimal local growth exponent α_min and the information dimension D_1 decrease, while the fractal dimension remains the same. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0512/0512125v1.pdf"}
{"id": "cond-mat0512378", "abstract": "  The transient tunneling current of single electron transistors (SETs) is theoretically investigated. The time-dependent current formula given by Jauho, Wingreen and Meir [Phys. Rev. B 50, 5528 (1994)] is applied to study the temperature effect on the transient current through a single quantum dot embedded into asymmetry barrier. It is found that the tunneling rate ratio significantly influences the feature of transient current. Finally, the oscillation structures on the exponential growth transient current of single hole transistors composed of germanium quantum dots is analyzed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0512/0512378v1.pdf"}
{"id": "cond-mat0512427", "abstract": "  We explore spin-1/2 triangular antiferromagnets with both easy-plane and lattice exchange anisotropies by employing a dual vortex mapping followed by a fermionization of the vortices. Over a broad range of exchange anisotropy, this approach leads naturally to a “critical” spin liquid–the algebraic vortex liquid–which appears to be distinct from other known spin liquids. We present a detailed characterization of this state, which is described in terms of non-compact QED3 with an emergent SU(4) symmetry. Descendant phases of the algebraic vortex liquid are also explored, which include the Kalmeyer-Laughlin spin liquid, a variety of magnetically ordered states such as the well known coplanar spiral state, and supersolids. In the range of exchange anisotropy where the “square lattice” Neel ground state arises, we demonstrate that anomalous “roton” minima in the excitation spectrum recently reported in series expansions can be accounted for within our approach. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0512/0512427v1.pdf"}
{"id": "cond-mat0512444", "abstract": "  A narrow energy band of the electronic spectrum in some direction in low-dimensional crystals may lead to a negative differential conductance and N-shaped I-V curve that results in an instability of the uniform stationary state. A well-known stable solution for such a system is a state with electric field domain. We have found a uniform stable solution in the region of negative differential conductance. This solution describes uniform high-frequency voltage oscillations. Frequency of the oscillation is determined by antenna properties of the system. The results are applicable also to semiconductor superlattices. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0512/0512444v1.pdf"}
{"id": "cond-mat0601578", "abstract": "  The crystallization of electrons in quasi low-dimensional solids is studied in a model which retains the full three-dimensional nature of the Coulomb interactions. We show that restricting the electron motion to layers (or chains) gives rise to a rich sequence of structural transitions upon varying the particle density. In addition, the concurrence of low-dimensional electron motion and isotropic Coulomb interactions leads to a sizeable stabilization of the Wigner crystal, which could be one of the mechanisms at the origin of the charge ordered phases frequently observed in such compounds. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0601/0601578v1.pdf"}
{"id": "cond-mat0602006", "abstract": "  At reduced dimensionality, Coulomb interactions play a crucial role in determining device properties. While such interactions within the same carbon nanotube have been shown to have unexpected properties, device integration and multi-nanotube devices require the consideration of inter-nanotube interactions. We present calculations of the characteristics of planar carbon nanotube transistors including interactions between semiconducting nanotubes and between semiconducting and metallic nanotubes. The results indicate that inter-tube interactions affect both the channel behavior and the contacts. For long channel devices, a separation of the order of the gate oxide thickness is necessary to eliminate inter-nanotube effects. Because of an exponential dependence of this length scale on dielectric constant, very high device densities are possible by using high-k dielectrics and embedded contacts. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0602/0602006v1.pdf"}
{"id": "cond-mat0602080", "abstract": "  We investigate the presence of squeezing in the weakly repulsive uniform Bose gas, in both the condensate mode and in the nonzero opposite-momenta mode pairs, using two different variational formulations. We explore the U(1) symmetry breaking and Goldstone's theorem in the context of a squeezed coherent variational wavefunction, and present the associated Ward identity. We show that squeezing of the condensate mode is absent at the mean field Hartree-Fock-Bogoliubov level and emerges as a result of fluctuations about mean field as a finite volume effect, which vanishes in the thermodynamic limit. On the other hand, the squeezing of the excitations about the condensate survives the thermodynamic limit and is interpreted in terms of density-phase variables using a number-conserving formulation of the interacting Bose gas. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0602/0602080v2.pdf"}
{"id": "cond-mat0602310", "abstract": "  We analyze the Thermodynamic Bethe Ansatz equations of the one-dimensional half-filled Hubbard model in the \"spin-disordered regime\", which is characterized by the temperature being much larger than the magnetic energy scale but small compared to the Mott-Hubbard gap. In this regime the thermodynamics of the Hubbard model can be thought of in terms of gapped charged excitations with an effective dispersion and spin degrees of freedom that only contribute entropically. In particular, the internal energy and the effective dispersion become essentially independent of temperature. An interpretation of this regime in terms of a putative interacting-electron system at zero temperature leads to a metal-insulator transition at a finite interaction strength above which the gap opens linearly. We relate these observations to studies of the Mott-Hubbard transition in the limit of infinite dimensions. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0602/0602310v2.pdf"}
{"id": "cond-mat0602472", "abstract": "  Low energy nuclear transmutations have been reported in experimental chemical electrolytic cells employing metallic hydride electrodes. Assuming that the nuclear transmutations are induced by ultra-low momentum neutron absorption, the expected chemical cell nuclear abundances are discussed on the basis of a neutron optical potential model. The theoretical results are in satisfactory agreement with available experimental chemical cell data. Some implications of these laboratory nuclear transmutations for r- s-process models of the neutron induced solar system and galactic nuclear abundance are briefly explored. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0602/0602472v1.pdf"}
{"id": "cond-mat0603018", "abstract": "  Glassy systems are characterized by an extremely sluggish dynamics without any simple sign of long range order. It is a debated question whether a correct description of such phenomenon requires the emergence of a large correlation length. We prove rigorous bounds between length and time scales implying the growth of a properly defined length when the relaxation time increases. Our results are valid in a rather general setting, which covers finite-dimensional and mean field systems.   As an illustration, we discuss the Glauber (heat bath) dynamics of p-spin glass models on random regular graphs. We present the first proof that a model of this type undergoes a purely dynamical phase transition not accompanied by any thermodynamic singularity. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0603/0603018v2.pdf"}
{"id": "cond-mat0603766", "abstract": "  The key feature of an orbital wave or orbiton is a significant dispersion, which arises from exchange interactions between orbitals on distinct sites. We study the effect of a coupling between orbitons and phonons in one dimension using continuous unitary transformations (CUTs). Already for intermediate values of the coupling, the orbiton band width is strongly reduced and the spectral density is dominated by an orbiton-phonon continuum. However, we find sharp features within the continuum and an orbiton-phonon anti-bound state above. Both show a significant dispersion and should be observable experimentally. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0603/0603766v2.pdf"}
{"id": "cond-mat0604258", "abstract": "  We generalize a class of Heisenberg antiferromagnets in one, two and three dimensions, which have been shown to exhibit magnetization plateaus for spin-1/2. In a certain parameter range of the general model, which is formally defined in D dimensions, we obtain the exact ground state(s) in the presence of an external magnetic field for arbitrary values of spin. In this range, the magnetization remains a constant as a function of the external field, except at some special values of the field where there is a jump from one plateau to the next. The plateaus are formed at certain specific fractions of the full magnetization which are determined by the spin and the lattice. Our general spin-S result reproduces the known cases for spin-1/2 in various lattices. Furthermore, we argue that outside the exact regime, the mechanism for the plateau formation is different. This results in first order phase transitions along some of the plateaus as the coupling constant is varied. We rigorously show the existence of such transitions for some particular cases. Finally, we numerically analyze a spin-1 model in one dimension using exact diagonalization to obtain its complete phase diagram. It agrees with our analytic results. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0604/0604258v1.pdf"}
{"id": "cond-mat0605112", "abstract": "  Structural order parameters of a smectic liquid crystal confined into the columnar form of porous silicon are studied using neutron scattering and optical spectroscopic techniques. It is shown that both the translational and orientational anisotropic properties of the confined phase strongly couple to the one-dimensional character of the porous silicon matrix. The influence of this confinement induced anisotropic local structure on the molecular reorientations occuring in the picosecond timescale is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0605/0605112v1.pdf"}
{"id": "cond-mat0605235", "abstract": "  A Molecular Dynamics approach has been used to compute the shear force resulting from the shearing of disks. Two-dimensional monodisperse disks have been put in an horizontal and rectangular shearing cell with periodic boundary conditions on right and left hand sides. The shear is applied by pulling the cover of the cell either at a constant rate or by pulling a spring, linked to the cover, with a constant force. Depending on the rate of shearing and on the elasticity of the whole set up, we showed that the measured shear force signal is either irregular in time, regular in time but not in shape, or regular in shape. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0605/0605235v1.pdf"}
{"id": "cond-mat0606627", "abstract": "  We propose a universal quantum computing scheme in which the orthogonal qubit states |0> and |1> are identical in their single-particle spin and charge properties. Each qubit is contained in a single quantum dot and gate operations are induced all-electrically by changes in the confinement potential. Within the computational space, these qubits are robust against environmental influences that couple to the system through single-particle channels. Due to the identical spin and charge properties of the |0>, |1> states, the lowest-order relaxation and decoherence rates 1/T_1 and 1/T_2, within the Born-Markov approximation, both vanish for a large class of environmental couplings. We give explicit pulse sequences for a universal set of gates (phase, π/8, Hadamard, cnot) and discuss state preparation, manipulation, and detection. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0606/0606627v2.pdf"}
{"id": "cond-mat0607454", "abstract": "  A novel strategy to encrypt covert information (code) via unitary projections into the null spaces of ill-conditioned eigenstructures of multiple host statistical distributions, inferred from incomplete constraints, is presented. The host pdf's are inferred using the maximum entropy principle. The projection of the covert information is dependent upon the pdf's of the host statistical distributions. The security of the encryption/decryption strategy is based on the extreme instability of the encoding process. A self-consistent procedure to derive keys for both symmetric and asymmetric cryptography is presented. The advantages of using a multiple pdf model to achieve encryption of covert information are briefly highlighted. Numerical simulations exemplify the efficacy of the model. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0607/0607454v2.pdf"}
{"id": "cond-mat0607706", "abstract": "  In the last several years considerable efforts have been devoted to developing Bose-Einstein Condensate (BEC)-based devices for applications such as fundamental research, precision measurements and integrated atom optics. Such devices capable of complex functionality can be designed from simpler building blocks as is done in microelectronics. One of the most important components of microelectronics is a transistor. We demonstrate that Bose-Einstein condensate in a three well potential structure where the tunneling of atoms between two wells is controlled by the population in the third, shows behavior similar to that of an electronic field effect transistor. Namely, it exhibits switching and both absolute and differential gain. The role of quantum fluctuations is analyzed, estimates of switching time and parameters for the potential are presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0607/0607706v2.pdf"}
{"id": "cond-mat0608556", "abstract": "  We discuss a simple model of the melting kinetics along the solid-solid interface in eutectic and peritectic systems. The process is controlled by the diffusion inside the liquid phase and the existence of a triple junction is crucial for the velocity selection problem. Using the lubrication approximation for the diffusion field in the liquid phase we obtain scaling results for the steady-state velocity of the moving pattern depending on the overheating above the equilibrium temperature and on the material parameters of the system, including the dependences on the angles at the triple junction. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0608/0608556v1.pdf"}
{"id": "cond-mat0609080", "abstract": "  We present a theoretical many-body analysis of the electron-electron (e-e) inelastic damping rate Γ of electron-like excitations in the Shockley surface state band of Ag(111). It takes into account ab-initio band structures for both bulk and surface states. Γ is found to increase more rapidly as a function of surface state energy E than previously reported, thus leading to an improved agreement with experimental data. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0609/0609080v1.pdf"}
{"id": "cond-mat0609303", "abstract": "  The nanoscale cylindrical Couette flow is investigated by means of molecular dynamics simulations, in the case where the inner cylinder is rotating whereas the outer cylinder is at rest. We find that the tangential velocity of the low is inverted when the fluid-wall interaction near the outer cylinder is weak and the fluid density is low. The unusual velocity inversion behavior is shown to be strongly related to the degree of the slip between the fluid and the outer cylinder, which is determined by the presence or absence of the layering of the fluid near the outer wall. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0609/0609303v2.pdf"}
{"id": "cond-mat0610597", "abstract": "  We address the problem of sampling double-ended diffusive paths. The ensemble of paths is expressed using a symmetric version of the Onsager-Machlup formula, which only requires evaluation of the force field and which, upon direct time discretization, gives rise to a symmetric integrator that is accurate to second order. Efficiently sampling this ensemble requires avoiding the well-known stiffness problem associated with sampling infinitesimal Brownian increments of the path, as well as a different type of stiffness associated with sampling the coarse features of long paths. The fine-feature sampling stiffness is eliminated with the use of the fast sampling algorithm (FSA), and the coarse-feature sampling stiffness is avoided by introducing the sliding and sampling (S   S) algorithm. A key feature of the S   S algorithm is that it enables massively parallel computers to sample diffusive trajectories that are long in time. We use the algorithm to sample the transition path ensemble for the structural interconversion of the 38-atom Lennard-Jones cluster at low temperature. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0610/0610597v2.pdf"}
{"id": "cond-mat0611033", "abstract": "  We report experimental measurements of particle dynamics in a colloidal glass in order to understand the dynamical heterogeneities associated with the cooperative motion of the particles in the glassy regime. We study the local and global fluctuation of correlation and response functions in an aging colloidal glass. The observables display universal scaling behavior following a modified power-law, with a plateau dominating the less heterogeneous short-time regime and a power-law tail dominating the highly heterogeneous long-time regime. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0611/0611033v1.pdf"}
{"id": "cond-mat0611677", "abstract": "  In this paper we review some results of our works on the magnetization processes in: i) Isolated nanomagnets, both in the one-spin approximation and as many-spin systems. Here, we focus on the intrinsic properties, e.g., those induced by finite-size, boundary and surface effects. We also investigate the crossover between the two regimes. ii) Assemblies of nanomagnets, also in the two situations. We focus on their behavior mainly due to dipole-dipole interactions. Then, we will comment on the interplay between these intrinsic and collective effects. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0611/0611677v1.pdf"}
{"id": "cond-mat0701186", "abstract": "  Arrays of metallic nanoparticles support individual and collective plasmonic excitations that contribute to unusual phenomena like surface enhanced Raman scattering, anomalous transparency, negative index, and subwavelength resolution in various metamaterials. We have examined the electromagnetic response of dual Kron's lattice and films containing up to three monolayers of metallic nanospheres. It appears that open cubic Kron's lattice exhibits `soft' electromagnetic response but no negative index behavior. The close-packed arrays behave similarly: there are plasmon resonances and very high transmission at certain wavelengths that are much larger than the separation between the particles, and a `soft' magnetic response, with small but positive effective index of refraction. It would be interesting to check those predictions experimentally. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0701/0701186v1.pdf"}
{"id": "cond-mat0702395", "abstract": "  We expose an interesting connection between the distribution of local spectral density of states arising in the theory of disordered systems and the notion of superstatistics introduced by Beck and Cohen and recently incorporated in random matrix theory. The latter represents the matrix-element joint probability density function as an average of the corresponding quantity in the standard random-matrix theory over a distribution of level densities. We show that this distribution is in reasonable agreement with the numerical calculation for a disordered wire, which suggests to use the results of theory of disordered conductors in estimating the parameter distribution of the superstatistical random-matrix ensemble. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0702/0702395v1.pdf"}
{"id": "cond-mat9409041", "abstract": "  We study the quantum chaotic dynamics of an initially well-localized wave packet in a cosine potential perturbed by an external time-dependent force. For our choice of initial condition and with ħ small but finite, we find that the wave packet behaves classically (meaning that the quantum behavior is indistinguishable from that of the analogous classical system) as long as the motion is confined to the interior of the remnant separatrix of the cosine potential. Once the classical motion becomes unbounded, however, we find that quantum interference effects dominate. This interference leads to a long-lived accumulation of quantum amplitude on top of the cosine barrier. This pinning of the amplitude on the barrier is a dynamic mechanism for the quantum inhibition of classical mixing. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9409/9409041v1.pdf"}
{"id": "cond-mat9506019", "abstract": "  We analyze pairing in two dimensional spin liquids. We argue that interplane pairing enhanced by magnetic correlations is the most plausible explanation of the spin gap phenomenon observed in underdoped cuprates. The details of the pairing theory depend on the in-plane antiferromagnetic correlations. We consider two models: 2p_F correlations induced by a strong gauge field interaction and undamped spin waves. We estimate the pairing temperature T_s and the angular dependence of the gap function and discuss physical consequences. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9506/9506019v1.pdf"}
{"id": "cond-mat9606211", "abstract": "  We predict a spatially varying mode population to appear in a GaAs/AlGaAs-2DEG ballistic quantum channel pumped by a THz-field. If a resonant coupling between two modes is suddenly switched on at the entrance, Rabi oscillations in the mode population will arise. We propose to use an array of gates in order to simulate a moving quantum point contact for detecting the mode population oscillations, since they discriminate between different modes. By consecutively activating them we expect to see both photovoltaic effects and photoconductive effects which can easily be distinguished from noise. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9606/9606211v1.pdf"}
{"id": "cond-mat9607212", "abstract": "  Many direct parallels connect superfluid 3He with the field theories describing the physical vacuum, gauge fields and elementary fermions. Superfluid ^3He exhibits a variety of topological defects which can be detected with single-defect sensitivity. Modern scenarios of defect-mediated baryogenesis can be simulated by the interaction of the 3He vortices and domain walls with fermionic quasiparticles. Formation of defects in a symmetry-breaking phase transition in the early Universe, which could be responsible for large-scale structure formation and for microwave-background anisotropy, also may be modelled in the laboratory. This is supported by the recent observation of vortex formation in neutron-irradiated 3He-B where the \"primordial fireball\" is formed in an exothermic nuclear reaction. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9607/9607212v1.pdf"}
{"id": "cond-mat9704189", "abstract": "  We study the reflection of electrons and quasiparticles on point-contact interfaces between fractional quantum Hall (FQH) states and normal metals (leads), as well as interfaces between two FQH states with mismatched filling fractions. We classify the processes taking place at the interface in the strong coupling limit. In this regime a set of quasiparticles can decay into quasiholes on the FQH side and charge excitations on the other side of the junction. This process is analogous to an Andreev reflection in normal-metal/superconductor (N-S) interfaces. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9704/9704189v3.pdf"}
{"id": "cond-mat9708057", "abstract": "  The decay rate of metastable states is determined at high temperatures by thermal activation, whereas at temperatures close to zero quantum tunneling is relevant. At some temperature T_c the transition from classical to quantum-dominated decay occurs. The transition can be first-order like, with a discontinuous first derivative of the Euclidean action, or smooth with only a second derivative developing a jump. In the former case the crossover temperature T_c cannot be calculated perturbatively and must be found as the intersection point of the Euclidean actions calculated at low and high temperatures. In this paper we present a sufficient criterion for a first-order transition in tunneling problems and apply it to the problem of the tunneling of strings. It is shown that the problem of the depinning of a massive string from a linear defect in the presence of an arbitrarily strong dissipation exhibits a first-order transition. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9708/9708057v1.pdf"}
{"id": "cond-mat9708097", "abstract": "  We investigate the effects of quenched disorder on two chain Hubbard models at half-filling by using bosonization and renormalization group methods. It is found that the sufficiently strong forward scattering due to impurities and the random gauge field, which is generated by impurity backward scattering, destroy the charge gaps as well as the spin gaps. Random backward scattering due to impurities then drives the resulting massless phase to the Anderson localization phase. For intermediate strength of random forward scattering, however, the spin gaps still survive, and only one of the charge gaps is collapsed. In this parameter region, one of the charge degrees of freedom is in the Anderson localized state, while the other one is still in the massive state. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9708/9708097v1.pdf"}
{"id": "cond-mat9711231", "abstract": "  Various aspects of the phase dynamics of an atom laser scheme based on binary collisions are investigated. Analytical estimates of the influence of elastic atom-atom collisions on the laser linewidth are given, and linewidths achievable in a recently proposed atom laser scheme [Phys. Rev. A 56, 2989 (1997)] are evaluated explicitly. The extent to which a relative phase can be established between two interfering atom lasers, as well as the properties of that phase, are also investigated. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9711/9711231v1.pdf"}
{"id": "cond-mat9803315", "abstract": "  We investigate a class of stochastic growth models involving competition between two phases in which one of the phases has a competitive advantage. The equilibrium populations of the competing phases are calculated using a mean field analysis. Regression probabilities for the extinction of the advantaged phase are calculated in a leading order approximation. The results of the calculations are in good agreement with simulations carried out on a square lattice with periodic boundaries. The class of models are variants of the Williams- Bjerknes model for the growth of tumours in the basal layer of an epithelium. In the limit in which only one of the phases is unstable the class of models reduces to the well known variants of the Eden model. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9803/9803315v1.pdf"}
{"id": "cond-mat9804070", "abstract": "  We investigate the stability of the square vortex lattice which has been recently observed in experiments on the borocarbide family of superconductors. Taking into account the tetragonal symmetry of these systems, we add fourfold symmetric fourth-derivative terms to the Ginzburg-Landau(GL) free energy. At H_c2 these terms may be treated perturbatively to lowest order to locate the transition from a distorted hexagonal to a square vortex lattice. We also solve for this phase boundary numerically in the strongly type-II limit, finding large corrections to the lowest-order perturbative results. We calculate the relative fourfold H_c2 anisotropy for field in the xy plane to be 4.5", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9804/9804070v1.pdf"}
{"id": "cond-mat9806012", "abstract": "  The electron-phonon vertex correction has a complex structure both in momentum and frequency. We explain this structure on the basis of physical considerations and we show how the vertex correction can be decomposed into two terms with different physical origins. In particular, the first term describes the lattice polarization induced by the electrons and it is essentially a single-electron process whereas the second term is governed by the particle-hole excitations due to the exchange part of the phonon-mediated electron-electron interaction. We show that by weakening the influence of the exchange interaction the vertex takes mostly positive values giving rise to an enhanced effective coupling in the scattering with phonons. This weakening of the exchange interaction can be obtained by lowering the density of the electrons, or by considering only long-ranged (small q) electron-phonon couplings. These findings permit to understand why in the High-Tc materials the small carrier density and the long ranged electron-phonon interaction may play a positive role in enhancing Tc. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9806/9806012v1.pdf"}
{"id": "cond-mat9809217", "abstract": "  We employ effective mass theory for degenerate hole-bands to calculate the acceptor binding energies for Be, Mg, Zn, Ca, C and Si substitutional acceptors in GaN and AlN. The calculations are performed through the 6×6 Rashba-Sheka-Pikus and the Luttinger-Kohn matrix Hamiltonians for wurtzite (WZ) and zincblende (ZB) crystal phases, respectively. An analytic representation for the acceptor pseudopotential is used to introduce the specific nature of the impurity atoms. The energy shift due to polaron effects is also considered in this approach. The ionization energy estimates are in very good agreement with those reported experimentally in WZ-GaN. The binding energies for ZB-GaN acceptors are all predicted to be shallower than the corresponding impurities in the WZ phase. The binding energy dependence upon the crystal field splitting in WZ-GaN is analyzed. Ionization levels in AlN are found to have similar `shallow' values to those in GaN, but with some important differences, which depend on the band structure parameterizations, especially the value of crystal field splitting used. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9809/9809217v1.pdf"}
{"id": "cond-mat9810069", "abstract": "  We study how energy transport in an integrable system is affected by the spectral densities of heat reservoirs. The model investigated here is the quantum harmonic chain whose both ends are in contact with two heat reservoirs at different temperatures. The master equation for the reduced density matrix is derived on the assumption that the reservoirs are composed of an infinite number of independent harmonic oscillators. We evaluate temperature profile and energy flux in the stationary state for the master equation and discuss how they depend on the types of spectral densities. When we attach the reservoirs of the same type of spectral density, we find that the temperature profile is independent of the types. On the other hand, when the two reservoirs have different types of spectral densities, the energy profile near the ends of the chain depends on the types. When the coupling is finite, the temperature profile near the ends shows wide variation of behavior dependent on spectral densities and temperatures of reservoirs. This dependence is discussed with the Fokker-Planck equations obtained in the classical limit. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9810/9810069v2.pdf"}
{"id": "cond-mat9810411", "abstract": "  The equilibrium crystal shape of a body-centered solid-on-solid (BCSOS) model on a honeycomb lattice is studied numerically. We focus on the facet ridge endpoints (FRE). These points are equivalent to one dimensional KPZ-type growth in the exactly soluble square lattice BCSOS model. In our more general context the transfer matrix is not stochastic at the FRE points, and a more complex structure develops. We observe ridge lines sticking into the rough phase where thesurface orientation jumps inside the rounded part of the crystal. Moreover, the rough-to-faceted edges become first-order with a jump in surface orientation, between the FRE point and Pokrovsky-Talapov (PT) type critical endpoints. The latter display anisotropic scaling with exponent z=3 instead of familiar PT value z=2. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9810/9810411v1.pdf"}
{"id": "cond-mat9811086", "abstract": "  When an interacting many-body system, such as a magnet, is driven in time by an external perturbation, such as a magnetic field,the system cannot respond instantaneously due to relaxational delay. The response of such a system under a time-dependent field leads to many novel physical phenomena with intriguing physics and important technological applications. For oscillating fields, one obtains hysteresis that would not occur under quasistatic conditions in the presence of thermal fluctuations. Under some extreme conditions of the driving field, one can also obtain a non-zero average value of the variable undergoing such dynamic hysteresis. This non-zero value indicates a breaking of symmetry of the hysteresis loop, around the origin. Such a transition to the spontaneously broken symmetric phase occurs dynamically when the driving frequency of the field increases beyond its threshold value which depends on the field amplitude and the temperature. Similar dynamic transitions also occur for pulsed and stochastically varying fields. We present an overview of the ongoing researches in this not-so-old field of dynamic hysteresis and transitions. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9811/9811086v1.pdf"}
{"id": "cond-mat9811193", "abstract": "  We study a three dimensional Abrikosov vortex lattice in the presence of an equilibrium concentration of vacancy, interstitial and dislocation loops. Vacancies and interstitials renormalize the long-wavelength bulk and tilt elastic moduli. Dislocation loops lead to the vanishing of the long-wavelength shear modulus. The coupling to vacancies and interstitials - which are always present in the liquid state - allows dislocations to relax stresses by climbing out of their glide plane. Surprisingly, this mechanism does not yield any further independent renormalization of the tilt and compressional moduli at long wavelengths. The long wavelength properties of the resulting state are formally identical to that of the “flux-line hexatic” that is a candidate “normal” hexatically ordered vortex liquid state. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9811/9811193v2.pdf"}
{"id": "cond-mat9908086", "abstract": "  Physical properties of ideal Bose gas with the fractal dimensionality between D=2 and D=3 are theoretically investigated. Calculation shows that the characteristic features of the specific heat and the superfluid density of ideal Bose gas in fractal dimensions are strikingly similar to those of superfluid Helium-4 in porous media. This result indicates that the geometrical factor is dominant over mutual interactions in determining physical properties of Helium-4 in porous media. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9908/9908086v1.pdf"}
{"id": "cond-mat9908243", "abstract": "  Thermal activation and macroscopic quantum tunneling in current-biased discrete Josephson transmission lines are studied theoretically. The degrees of freedom under consideration are the phases across the junctions which are coupled to each other via the inductances of the system. The resistively shunted junctions that we investigate constitute a system of N interacting degrees of freedom with an overdamped dynamics. We calculate the decay rate within exponential accuracy as a function of temperature and current. Slightly below the critical current, the decay from the metastable state occurs via a unique (\"rigid\") saddlepoint solution of the Euclidean action describing the simultaneous decay of the phases in all the junctions. When the current is reduced, a crossover to a regime takes place, where the decay occurs via an \"elastic\" saddlepoint solution and the phases across the junctions leave the metastable state one after another. This leads to an increased decay rate compared with the rigid case both in the thermal and the quantum regime. The rigid-to-elastic crossover can be sharp or smooth analogous to first- or second- order phase transitions, respectively. The various regimes are summarized in a current-temperature decay diagram. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9908/9908243v2.pdf"}
{"id": "cond-mat9909235", "abstract": "  Using a carefully justified development of Debye-Huckel theory for highly asymmetric electrolytes, one finds that a region of expanded phase instability, or miscibility gap, can appear for charge-stabilised colloidal suspensions at high charges and low ionic strengths. It is argued that this is offers a straightforward explanation for the observations of void structures and other anomalies in such suspensions in this region. The nature of the interface between coexisting phases, and general arguments that many-body attractions form a key part of the underlying physical picture, are also examined. The present analysis may also generate new insights into old problems such as coacervation in oppositely charged colloid or protein / polyelectrolyte mixtures, and suggests interesting new possibilities such as the appearance of charge density wave phases in colloidal systems in the vicinity of the critical solution points. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9909/9909235v2.pdf"}
{"id": "cond-mat9910315", "abstract": "  We present a theoretical analysis of the nonlinear bias and temperature dependence of current-voltage characteristics of a spin-valve device which is formed by connecting a quantum dot to two ferromagnetic electrodes whose magnetic moments orient at an angle θ with respect to each other. The theory is based on nonequilibrium Green's function approach and focused on current perpendicular to plane geometry. Coulomb interaction has been taken into account explicitly at the Hartree level. We derive a formula in closed form for current flowing through the device in general terms of bias and temperature. In the wideband limit we report exact results for the TMR junction nonlinear I-V curve as a function of θ. We also report the conductance slope at zero bias as a function of temperature for which experimental results reported an anomalous behavior. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9910/9910315v1.pdf"}
{"id": "cond-mat9911129", "abstract": "  Using a Monte Carlo coarse-graining technique introduced by Binder et al., we have explicitly constructed the continuum field theory for the zero-temperature triangular Ising antiferromagnet. We verify the conjecture that this is a gaussian theory of the height variable in the interface representation of the spin model. We also measure the height-height correlation function and deduce the stiffness constant. In addition, we investigate the nature of defect-defect interactions at finite temperatures, and find that the two-dimensional Coulomb gas scenario applies at low temperatures. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9911/9911129v2.pdf"}
{"id": "cs0101023", "abstract": "  We study the properties of input-consuming derivations of moded logic programs. Input-consuming derivations can be used to model the behavior of logic programs using dynamic scheduling and employing constructs such as delay declarations.   We consider the class of nicely-moded programs and queries. We show that for these programs a weak version of the well-known switching lemma holds also for input-consuming derivations. Furthermore, we show that, under suitable conditions, there exists an algebraic characterization of termination of input-consuming derivations. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0101/0101023v1.pdf"}
{"id": "cs0212055", "abstract": "  Theoretical computer science has found fertile ground in many areas of mathematics. The approach has been to consider classical problems through the prism of computational complexity, where the number of basic computational steps taken to solve a problem is the crucial qualitative parameter. This new approach has led to a sequence of advances, in setting and solving new mathematical challenges as well as in harnessing discrete mathematics to the task of solving real-world problems.   In this talk, I will survey the development of modern cryptography – the mathematics behind secret communications and protocols – in this light. I will describe the complexity theoretic foundations underlying the cryptographic tasks of encryption, pseudo-randomness number generators and functions, zero knowledge interactive proofs, and multi-party secure protocols. I will attempt to highlight the paradigms and proof techniques which unify these foundations, and which have made their way into the mainstream of complexity theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0212/0212055v1.pdf"}
{"id": "cs0502036", "abstract": "  An algorithm of improving the performance of iterative decoding on perpendicular magnetic recording is presented. This algorithm follows on the authors' previous works on the parallel and serial concatenated turbo codes and low-density parity-check codes. The application of this algorithm with signal-to-noise ratio mismatch technique shows promising results in the presence of media noise. We also show that, compare to the standard iterative decoding algorithm, an improvement of within one order of magnitude can be achieved. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0502/0502036v1.pdf"}
{"id": "cs0504021", "abstract": "  Cooperative optimization is a new way for finding global optima of complicated functions of many variables. It has some important properties not possessed by any conventional optimization methods. It has been successfully applied in solving many large scale optimization problems in image processing, computer vision, and computational chemistry. This paper shows the application of this optimization principle in decoding LDPC codes, which is another hard combinatorial optimization problem. In our experiments, it significantly out-performed the sum-product algorithm, the best known method for decoding LDPC codes. Compared to the sum-product algorithm, our algorithm reduced the error rate further by three fold, improved the speed by six times, and lowered error floors dramatically in the decoding. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0504/0504021v1.pdf"}
{"id": "cs0506022", "abstract": "  Minimum Description Length (MDL) is an important principle for induction and prediction, with strong relations to optimal Bayesian learning. This paper deals with learning non-i.i.d. processes by means of two-part MDL, where the underlying model class is countable. We consider the online learning framework, i.e. observations come in one by one, and the predictor is allowed to update his state of mind after each time step. We identify two ways of predicting by MDL for this setup, namely a static and a dynamic one. (A third variant, hybrid MDL, will turn out inferior.) We will prove that under the only assumption that the data is generated by a distribution contained in the model class, the MDL predictions converge to the true values almost surely. This is accomplished by proving finite bounds on the quadratic, the Hellinger, and the Kullback-Leibler loss of the MDL learner, which are however exponentially worse than for Bayesian prediction. We demonstrate that these bounds are sharp, even for model classes containing only Bernoulli distributions. We show how these bounds imply regret bounds for arbitrary loss functions. Our results apply to a wide range of setups, namely sequence prediction, pattern classification, regression, and universal induction in the sense of Algorithmic Information Theory among others. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0506/0506022v1.pdf"}
{"id": "cs0608037", "abstract": "  In this paper, the author proposes a series of multilevel double hashing schemes called cascade hash tables. They use several levels of hash tables. In each table, we use the common double hashing scheme. Higher level hash tables work as fail-safes of lower level hash tables. By this strategy, it could effectively reduce collisions in hash insertion. Thus it gains a constant worst case lookup time with a relatively high load factor(70", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0608/0608037v2.pdf"}
{"id": "cs0609068", "abstract": "  Prior work on routing in delay tolerant networks (DTNs) has commonly made the assumption that each pair of nodes shares the same inter-contact time distribution as every other pair. The main argument in this paper is that researchers should also be looking at heterogeneous inter-contact time distributions. We demonstrate the presence of such heterogeneity in the often-used Dartmouth Wi-Fi data set. We also show that DTN routing can benefit from knowing these distributions. We first introduce a new stochastic model focusing on the inter-contact time distributions between all pairs of nodes, which we validate on real connectivity patterns. We then analytically derive the mean delivery time for a bundle of information traversing the network for simple single copy routing schemes. The purpose is to examine the theoretic impact of heterogeneous inter-contact time distributions. Finally, we show that we can exploit this user diversity to improve routing performance. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0609/0609068v2.pdf"}
{"id": "cs0609131", "abstract": "  In this paper, we propose a fast 2-D block-based motion estimation algorithm called Particle Swarm Optimization - Zero-motion Prejudgment(PSO-ZMP) which consists of three sequential routines: 1)Zero-motion prejudgment. The routine aims at finding static macroblocks(MB) which do not need to perform remaining search thus reduces the computational cost; 2)Predictive image coding and 3)PSO matching routine. Simulation results obtained show that the proposed PSO-ZMP algorithm achieves over 10 times of computation less than Diamond Search(DS) and 5 times less than the recent proposed Adaptive Rood Pattern Searching(ARPS). Meanwhile the PSNR performances using PSO-ZMP are very close to that using DS and ARPS in some less-motioned sequences. While in some sequences containing dense and complex motion contents, the PSNR performances of PSO-ZMP are several dB lower than that using DS and ARPS but in an acceptable degree. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0609/0609131v1.pdf"}
{"id": "cs9904020", "abstract": "  This paper describes an architecture for a distributing processing system that would allow remote procedure calls to invoke other services as messages are passed between clients and servers. It proposes that an additional class of data processing objects be located in the software communications channel. The objects in this channel would then be used to enforce protocols on client-server applications without any additional effort by the application programmers. For example, services such as key-management, time-stamping, sequencing and encryption can be implemented at different levels of the software communications stack to provide a complete authentication service. A distributing processing environment could be used to control broadband network data delivery. Architectures and invocation semantics are discussed, Example classes and interfaces for channel objects are given in the Java programming language. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/9904/9904020v1.pdf"}
{"id": "gr-qc0001083", "abstract": "  By applying a standard solution generating technique, we transform an arbitrary vacuum Mixmaster solution on S^3 × R to a new solution which is spatially inhomogeneous. We thereby obtain a family of exact, spatially inhomogeneous, vacuum spacetimes which exhibit Belinskii, Khalatnikov, and Lifshitz (BKL) oscillatory behavior. The solutions are constructed explicitly by performing the transformations on numerically generated, homogeneous Mixmaster solutions. Their behavior is found to be qualitatively like that seen in previous numerical simulations of generic U(1) symmetric cosmological spacetimes on T^3 × R. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0001/0001083v1.pdf"}
{"id": "gr-qc0208050", "abstract": "  Using a novel approach, we work out the general relativistic effects on the quantum interference of de Broglie waves associated with thermal neutrons. The unified general formula is consistent with special relativistic results in the flat space limit. It is also shown that the exact geodesic equation contains in a natural way a gravitational analog of the Aharonov-Bohm effect. We work out two examples, one in general relativity and the other in heterotic string theory, in order to obtain the first order gravitational correction terms to the quantum fringe shift. Measurement of these terms is closely related to the validity of the equivalence principle at a quantum level. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0208/0208050v1.pdf"}
{"id": "gr-qc0209106", "abstract": "  In order to obtain stable and accurate general relativistic simulations, re-formulations of the Einstein equations are necessary. In a series of our works, we have proposed using eigenvalue analysis of constraint propagation equations for evaluating violation behavior of constraints. In this article, we classify asymptotical behaviors of constraint-violation into three types (asymptotically constrained, asymptotically bounded, and diverge), and give their necessary and sufficient conditions. We find that degeneracy of eigenvalues sometimes leads constraint evolution to diverge (even if its real-part is not positive), and conclude that it is quite useful to check the diagonalizability of constraint propagation matrices. The discussion is general and can be applied to any numerical treatments of constrained dynamics. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0209/0209106v3.pdf"}
{"id": "gr-qc0312103", "abstract": "  For many years, the most active area of quantum cosmology has been the issue of choosing boundary conditions for the wave function of a universe. Recently, loop quantum cosmology, which is obtained from loop quantum gravity, has shed new light on this question. In this case, boundary conditions are not chosen by hand with some particular physical intuition in mind, but they are part of the dynamical law. It is then natural to ask if there are any relations between these boundary conditions and the ones provided before. After discussing the technical foundation of loop quantum cosmology which leads to crucial differences to the Wheeler-DeWitt quantization, we compare the dynamical initial conditions of loop quantum cosmology with the tunneling and the no-boundary proposal and explain why they are closer to the no-boundary condition. We end with a discussion of recent developments and several open problems of loop quantum cosmology. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0312/0312103v1.pdf"}
{"id": "gr-qc0406030", "abstract": "  The resolution of the problem of cosmological singularity in the framework of gauge theories of gravitation is discussed. Generalized cosmological Friedmann equations for homogeneous isotropic models filled by interacting scalar fields and usual gravitating matter are deduced. It is shown that generic feature of cosmological models of flat, open and closed type is their regular bouncing character. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0406/0406030v1.pdf"}
{"id": "gr-qc0510078", "abstract": "  We examine the importance of second order corrections to linearized cosmological perturbation theory in an inflationary background, taken to be a spatially flat FRW spacetime. The full second order problem is solved in the sense that we evaluate the effect of the superhorizon second order corrections on the inhomogeneous and homogeneous modes of the linearized flucuations. These second order corrections enter in the form of a cumulative contribution from all of their Fourier modes. In order to quantify their physical significance we study their effective equation of state by looking at the perturbed energy density and isotropic pressure to second order. We define the energy density (isotropic pressure) in terms of the (averaged) eigenvalues associated with timelike (spacelike) eigenvectors of a total stress energy for the metric and matter fluctuations. Our work suggests that that for many parameters of slow-roll inflation, the second order contributions to these energy density and pressures may dominate over the first order effects for the case of super-Hubble evolution. These results hold in our choice of first and second order coordinate conditions however we also argue that other `reasonable` coordinate conditions do not alter the relative importance of the second order terms. We find that these second order contributions approximately take the form of a cosmological constant in this coordinate gauge, as found by others using effective methods. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0510/0510078v1.pdf"}
{"id": "gr-qc0510100", "abstract": "  The vacuum expectation value of the stress energy tensor for a massive scalar field with arbitrary coupling in flat spaces with non-trivial topology is discussed. We calculate the Casimir energy in these spaces employing the recently proposed optical approach based on closed classical paths. The evaluation of the Casimir energy consists in an expansion in terms of the lengths of these paths. We will show how different paths with corresponding weight factors contribute in the calculation. The optical approach is also used to find the mass and temperature dependence of the Casimir energy in a cavity and it is shown that the massive fields cannot be neglected in high and low temperature regimes. The same approach is applied to twisted as well as spinor fields and the results are compared with those in the literature. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0510/0510100v2.pdf"}
{"id": "gr-qc0605011", "abstract": "  After a brief introduction, basic ideas of the quantum Riemannian geometry underlying loop quantum gravity are summarized. To illustrate physical ramifications of quantum geometry, the framework is then applied to homogeneous isotropic cosmology. Quantum geometry effects are shown to replace the big bang by a big bounce. Thus, quantum physics does not stop at the big-bang singularity. Rather there is a pre-big-bang branch joined to the current post-big-bang branch by a `quantum bridge'. Furthermore, thanks to the background independence of loop quantum gravity, evolution is deterministic across the bridge. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0605/0605011v2.pdf"}
{"id": "gr-qc9312026", "abstract": "  The Wheeler-DeWitt equation is derived from the bosonic sector of the heterotic string effective action assuming a toroidal compactification. The spatially closed, higher dimensional Friedmann-Robertson-Walker (FRW) cosmology is investigated and a suitable change of variables rewrites the equation in a canonical form. Real- and imaginary-phase exact solutions are found and a method of successive approximations is employed to find more general power series solutions. The quantum cosmology of the Bianchi IX universe is also investigated and a class of exact solutions is found. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/9312/9312026v1.pdf"}
{"id": "gr-qc9606061", "abstract": "  This is a brief and updated summary of a talk given at the International Conference on Gravitation and Cosmology that took place in Poona in December 1995. It is very brief and is mostly intended as a guide to current literature, or to keep people updated only in very broad terms on the latest developments in the subject. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/9606/9606061v1.pdf"}
{"id": "gr-qc9607054", "abstract": "  We present detailed calculations of the quasinormal modes of Reissner-Nordstrom black holes. While the first few, slowly damped, modes depend on the charge of the black hole in a relatively simple way, we find that the rapidly damped modes show several peculiar features. The higher modes generally spiral into the value for the extreme black hole as the charge increases. We also discuss the possible existence of a purely imaginary mode for the Schwarzschild black hole: Our data suggest that there is a quasinormal mode that limits to ω M = -2i as Q→ 0. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/9607/9607054v1.pdf"}
{"id": "gr-qc9708022", "abstract": "  Numerical relativity codes now being developed will evolve initial data representing colliding black holes at a relatively late stage in the collision. The choice of initial data used for code development has been made on the basis of mathematical definitiveness and usefulness for computational implementation. By using the “particle limit” (the limit of an extreme ratio of masses of colliding holes) we recently showed that the standard choice is not a good representation of astrophysically generated initial data. Here we show that, for the particle limit, there is a very simple alternative choice that appears to give excellent results. That choice, “convective” initial data is, roughly speaking, equivalent to the start of a time sequence of parameterized solutions of the Hamiltonian constraint; for a particle in circular orbit, it is the initial data of the steady state solution on any hypersurface. The implementation of related schemes for equal mass holes is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/9708/9708022v1.pdf"}
{"id": "gr-qc9709073", "abstract": "  The spatially homogeneous, isotropic Standard Cosmological Model appears to describe our Universe reasonably well. However, Einstein's equations allow a much larger class of cosmological solutions. Theorems originally due to Penrose and Hawking predict that all such models (assuming reasonable matter properties) will have an initial singularity. The nature of this singularity in generic cosmologies remains a major open question in general relativity. Spatially homogeneous but possibly anisotropic cosmologies have two types of singularities: (1) velocity dominated—(reversing the time direction) the universe evolves to the singularity with fixed anisotropic collapse rates ; (2) Mixmaster—the anisotropic collapse rates change in a deterministically chaotic way. Much less is known about spatially inhomogeneous universes. Belinskii, Khalatnikov, and Lifshitz (BKL) claimed long ago that a generic universe would evolve toward the singularity as a different Mixmaster universe at each spatial point. We shall report on the results of a program to test the BKL conjecture numerically. Results include a new algorithm to evolve homogeneous Mixmaster models, demonstration of velocity dominance and understanding of evolution toward velocity dominance in the plane symmetric Gowdy universes (spatial dependence in one direction), demonstration of velocity dominance in polarized U(1) symmetric cosmologies (spatial dependence in two directions), and exploration of departures from velocity dominance in generic U(1) universes. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/9709/9709073v1.pdf"}
{"id": "gr-qc9905012", "abstract": "  The fluctuations of the flux radiated by an evaporating black hole will be discussed. Two approaches to this problem will be adopted. In the first, the squared flux operator is defined by normal ordering. In this case, both the mean flux and the mean squared flux are well defined local quantites. It is shown that the flux undergoes large fluctuations on a time scale of the order of the black hole's mass. Thus the semiclassical theory of gravity, in which a classical gravitational field is coupled to the expectation value of the stress tensor, breaks down below this time scale. In the second approach, one does not attempt to give meaning to the squared flux as a local quantity, but only as a time-averaged quantity. In both approaches, the mean squared mass minus the square of the mean mass grows linearly in time, but four times as fast in the second approach as in the first. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/9905/9905012v1.pdf"}
{"id": "hep-ex0005046", "abstract": "  The feasibility of a next generation underground water Cherenkov detector is examined and a conceptual design (UNO) is presented. The design has a linear detector configuration with a total volume of 650 kton which is 13 times the total volume of the Super-Kamiokande detector. It corresponds to a 20 times increase in fiducial volume for physics analyses. The physics goals of UNO are to increase the sensitivity of the searches for nucleon decays about a factor of ten and to make precision measurements of the solar and atmospheric neutrino properties. In addition, the detection sensitivity for Supernova neutrinos will reach as far as the Andromeda galaxy. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ex/pdf/0005/0005046v1.pdf"}
{"id": "hep-ex0111007", "abstract": "  BTeV is a B-physics experiment that expects to begin collecting data at the C0 interaction region of the Fermilab Tevatron in the year 2006. Its primary goal is to achieve unprecedented levels of sensitivity in the study of CP violation, mixing, and rare decays in b and c quark systems. In order to realize this, it will employ a state-of-the-art first-level vertex trigger (Level 1) that will look at every beam crossing to identify detached secondary vertices that provide evidence for heavy quark decays. This talk will briefly describe the BTeV detector and trigger, focus on the software and hardware aspects of the Level 1 vertex trigger, and describe work currently being done in these areas. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ex/pdf/0111/0111007v1.pdf"}
{"id": "hep-ex9905053", "abstract": "  This paper summarizes the contributions to the experimental sessions on polarized lepton nucleon scattering at the DIS 99 workshop. Results are reported about the flavor decomposition of the quark polarization, a first direct measurement of a positive gluon polarization, the observation of a double-spin asymmetry in diffractive rho production, the polarization of lambda hyperons, the observation of transverse single-spin asymmetries and the measurement of the Gerasimov-Drell-Hearn sum rule. Prospects of future fixed target and collider facilities are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ex/pdf/9905/9905053v1.pdf"}
{"id": "hep-lat0112028", "abstract": "  Quark propagators with arbitrary sources and sinks can be obtained more efficiently using a pseudofermion method with a mode-shifted action. Mode-shifting solves the problem of critical slowing down (for light quarks) induced by low eigenmodes of the Dirac operator. The method allows the full physical content of every gauge configuration to be extracted, and should be especially helpful for unquenched QCD calculations. The method can be applied for all the conventional quark actions: Wilson, Sheikoleslami-Wohlert, Kogut-Susskind, as well as Ginsparg-Wilson compliant overlap actions. The statistical properties of the method are examined and examples of physical processes under study are presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/0112/0112028v1.pdf"}
{"id": "hep-lat0203028", "abstract": "  We motivate lattice QCD studies of the parity-violating pion-nucleon coupling constant and extend flavor-conserving hadronic parity-violation from QCD to partially-quenched QCD. The parity-violating pion-nucleon coupling and the anapole form factor (and moment) of the proton are computed to one-loop order in the partially-quenched chiral expansion. For the parity-violating pion-nucleon interaction, we include the contributions from total derivative operators necessary to match the kinematics that will be used in lattice simulations. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/0203/0203028v1.pdf"}
{"id": "hep-lat0212033", "abstract": "  We study dynamical mass generation in QED in (2+1) dimensions using Hamiltonian lattice methods. We use staggered fermions, and perform simulations with explicit dynamical fermions in the chiral limit. We demonstrate that a recently developed method to reduce the fermion sign problem can successfully be applied to this problem. Our results are in agreement with both the strong coupling expansion and with Euclidean lattice simulations. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/0212/0212033v1.pdf"}
{"id": "hep-lat0309085", "abstract": "  The aim of the GRAL project is to simulate full QCD with standard Wilson fermions at light quark masses on small to medium-sized lattices and to obtain infinite-volume results by extrapolation. In order to establish the functional form of the volume dependence we study systematically the finite-size effects in the light hadron spectrum. We give an update on the status of the GRAL project and show that our simulation data for the light hadron masses depend exponentially on the lattice size. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/0309/0309085v1.pdf"}
{"id": "hep-lat0312004", "abstract": "  The two-nucleon sector is near an infrared fixed point of QCD and as a result the S-wave scattering lengths are unnaturally large compared to the effective ranges and shape parameters. It is usually assumed that a lattice QCD simulation of the two-nucleon sector will require a lattice that is much larger than the scattering lengths in order to extract quantitative information. In this paper we point out that this does not have to be the case: lattice QCD simulations on much smaller lattices will produce rigorous results for nuclear physics. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/0312/0312004v1.pdf"}
{"id": "hep-lat0610089", "abstract": "  We study pure SU(3) gauge theory on a large lattice, using Schrodinger's equation. Our approximate solution uses a basis of roughly 1000 states. Gauge invariance is recovered when the color content of the ground state is extrapolated to zero. We are able to identify the gauge invariant excitations that remain when the extrapolation is performed. In the weak coupling limit, we obtain promising results when we compare the excitation energies (masses) to known results, which we derive. We discuss the application of our nonperturbative method to the regime where glueballs are present. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/0610/0610089v1.pdf"}
{"id": "hep-lat0612013", "abstract": "  We review several results that have been obtained using lattice QCD with the staggered quark formulation. Our focus is on the quantities that have been calculated numerically with low statistical errors and have been extrapolated to the physical quark mass limit and continuum limit using staggered chiral perturbation theory. We limit our discussion to a brief introduction to staggered quarks, and applications of staggered chiral perturbation theory to the pion mass, decay constant, and heavy-light meson decay constants. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/0612/0612013v1.pdf"}
{"id": "hep-lat9305024", "abstract": "  Applying a variational method to a Gaussian wave ansatz, we have derived a set of semi-classical evolution equations for SU(2) lattice gauge fields, which take the classical form in the limit of a vanishing width of the Gaussian wave packet. These equations are used to study the quantum effects on the classical evolutions of the lattice gauge fields. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/9305/9305024v1.pdf"}
{"id": "hep-lat9808055", "abstract": "  Abelian gauge theories formulated on a space-time lattice can be used as a prototype for investigating the confinement mechanism. In U(1) lattice gauge theory it is possible to perform a dual transformation of the path integral. Simulating the obtained dual theory (which corresponds to a certain limit of a dual Higgs model) including external sources, we perform a very accurate analysis of flux tubes with respect to the dual superconductor picture. Dual flux tube simulations are also performed in the full Abelian Higgs model, in order to obtain non-perturbative control over quantum and string fluctuations, and for a comparison to the results of dual QCD. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/9808/9808055v1.pdf"}
{"id": "hep-lat9809163", "abstract": "  We investigate the monopole-instanton correlation in SU(2) lattice gauge theory using a renormalisation group inspired smoothing technique. We look at the properties of monopole clusters and their correlation with instantons. Since the action of the smoothed configurations is dominated by instantons we compare the smoothed Monte Carlo lattices to artificially reconstructed configurations with the same instanton content but no other fluctuations. Both parallel and randomly rotated (in group space) instanton ensembles are considered. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/9809/9809163v1.pdf"}
{"id": "hep-ph0001027", "abstract": "  Interpretation and understanding of the evidence for neutrino oscillations depends on knowledge of the atmospheric neutrino beam. In this talk I assess how well various features are known. The goal is to determine to what extent uncertainties in the neutrino beam may limit the conclusions about neutrino properties and which features of the evidence for neutrino oscillations are most robust. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0001/0001027v1.pdf"}
{"id": "hep-ph0001030", "abstract": "  We analyze the potentiality of the CERN Large Hadron Collider to probe the Higgs boson couplings to the electroweak gauge bosons. We parametrize the possible deviations of these couplings due to new physics in a model independent way, using the most general dimension–six effective lagrangian where the SU(2)_L x U(1)_Y is realized linearly. For intermediate Higgs masses, the decay channel into two photons is the most important one for Higgs searches at the LHC. We study the effects of these new interactions on the Higgs production mechanism and its subsequent decay into two photons. We show that the LHC will be sensitive to new physics scales beyond the present limits extracted from the LEP and Tevatron physics. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0001/0001030v1.pdf"}
{"id": "hep-ph0011308", "abstract": "  The equation of state for a superconducting cosmic string whose current is due to fermionic zero modes is derived analytically in the case where the back-reaction of the fermions to the background is neglected. It is first shown that the zero mode fermions follow a zero temperature distribution because of their interactions (or lack thereof) with the string-forming Higgs and gauge fields. It is then found that the energy per unit length U and the tension T are related to the background string mass m through the simple relation U+T=2m*m. Cosmological consequences are briefly discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0011/0011308v1.pdf"}
{"id": "hep-ph0106266", "abstract": "  Effects caused by the event-by-event fluctuation of the initial conditions in hydrodynamical description of high-energy heavy-ion collisions are investigated. Non-negligible effects appear for several observable quantities, even for a fixed impact parameter b⃗. They are sensitive to the equation of state, being the dispersions of the observable quantities in general smaller when the QGP phase appears at the beginning of hydrodynamic evolution than when the fluid remains hadron gas during whole the evolution. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0106/0106266v1.pdf"}
{"id": "hep-ph0107143", "abstract": "  We consider decay of the inflaton with a quartic potential coupled to other fields, including gravity, but restricted to spherical symmetry. We describe analytically an early, quasilinear regime, during which inflaton fluctuations and the metric functions are driven by nonlinear effects of the decay products. We present a detailed study of the leading nonlinear effects in this regime. Results of the quasilinear approximation, in its domain of applicability, are found to be consistent with those of fully nonlinear lattice studies. We discuss how these results may be promoted to the full three dimensions. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0107/0107143v1.pdf"}
{"id": "hep-ph0111038", "abstract": "  We study the electric and chromo electric dipole moment of top quark in the general two Higgs Doublet model (model III). We analyse the dependency of this quantity to the new phases coming from the complex Yukawa couplings and masses of charged and neutral Higgs bosons. We observe that the electric and chromo elecric dipole moments of top quark are at the order of 10^-21 e cm and 10^-20 g_s cm, which are extremely large values compared to ones calculated in the SM and also two Higgs Doublet model with real Yukawa couplings. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0111/0111038v2.pdf"}
{"id": "hep-ph0112058", "abstract": "  In this talk I review NRQCD predictions for the production of charmonium at the Tevatron. After a quick presentation of the NRQCD factorization formalism for production and decay I review some old results and discuss how they compare to recent data. Following this I discuss some recent work done with Adam Leibovich and Ira Rothstein. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0112/0112058v1.pdf"}
{"id": "hep-ph0201278", "abstract": "  By remaining strictly within the confines of QCD, i.e., without invoking the parton model or any other exogenous element, we identify and resum perturbatively to leading order, along with a correction term, enhanced radiative gluon contributions to the Drell-Yan type (qq̅ pair annihilation) and deep-inelastic-scattering type (eq→ eq+X) cross-sections. The key feature of the adopted approach is the recasting of QCD in terms of a space-time mode of description, which employs a path-integral formulation of field theories, as originally implied in works of Fock, Feynman and Schwinger. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0201/0201278v2.pdf"}
{"id": "hep-ph0202146", "abstract": "  We shortly review the various methods suggested for determining the transversity function. Among such methods, we consider especially those based on semi-inclusive deep inelastic scattering. In the framework of this kind of reactions, we propose to measure a double spin asymmetry, using a transversely polarized proton target and a longitudinally polarized lepton beam, and fixing the direction of the final pion. Under particular conditions, the asymmetry is sensitive to the transversity function. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0202/0202146v1.pdf"}
{"id": "hep-ph0206099", "abstract": "  We compute the 4D low energy effective gauge coupling at one-loop order in the compact Randall-Sundrum scenario with bulk gauge fields and charged matter, within controlled approximations. While such computations are subtle, they can be important for studying phenomenological issues such as grand unification. Ultraviolet divergences are cut-off using Pauli-Villars regularization so as to respect 5D gauge and general coordinate invariance. The structure of these divergences on branes and in the bulk is elucidated by a 5D position-space analysis. The remaining finite contributions are obtained by a careful analysis of the Kaluza-Klein spectrum. We comment on the agreement between our results and expectations based on the AdS/CFT correspondence, in particular logarithmic sensitivity to the 4D Planck scale. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0206/0206099v4.pdf"}
{"id": "hep-ph0211089", "abstract": "  We summarize the status of calculations of the electroweak radiative corrections to W and Z boson production via the Drell-Yan mechanism at hadron colliders. To fully exploit the precision physics potential of the high-luminosity environment of the Fermilab Tevatron pbar p (Run II) and the CERN LHC pp colliders, it is crucial that the theoretical predictions are well under control. The envisioned precision physics program includes a precise measurement of the W boson mass and width, and the (leptonic) weak mixing angle, as well as probing the Standard Model (SM) of electroweak interactions at the highest accessible center-of-mass energies. Some numerical results are presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0211/0211089v1.pdf"}
{"id": "hep-ph0212011", "abstract": "  Several stimulating open questions in high energy spin physics will be described together with the striking progress recently achieved in this field. In view of the new experimental facilities and the new tools, soon available, I will try to anticipate what we will learn next. The prospects for the future are excellent and clearly, some exciting times are ahead of us. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0212/0212011v1.pdf"}
{"id": "hep-ph0307163", "abstract": "  We calculate the lepton electric dipole moments in a class of supersymmetric seesaw models and explore the possibility that they may provide a way to probe some of the CP violating phases responsible for the origin of matter via leptogenesis. We show that in models where the right handed neutrino masses, M_R arise from the breaking of local B-L symmetry by a Higgs field with B-L=2, some of the leptogenesis phases can lead to enhancement of the lepton dipole moments compared to the prediction of models where M_R is either directly put in by hand or is a consequence of a higher dimensional operator. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0307/0307163v2.pdf"}
{"id": "hep-ph0307313", "abstract": "  In this work we examine the possible existence of new physics beyond the standard model which could modify the branching fractions of the leptonic (mainly tauonic) decays of bottomonium vector resonances below the BB̅ threshold. The decay width is factorized as the product of two pieces: a) the probability of an intermediate pseudoscalar color-singlet bb̅ state (coupling to the dominant Fock state of the Upsilon via a magnetic dipole transition) and a soft (undetected) photon; b) the annihilation width of the bb̅ pair into two leptons, mediated by a non-standard CP-odd Higgs boson of mass about 10 GeV, introducing a quadratic dependence on the lepton mass in the partial width. The process would be unwittingly ascribed to the Υ leptonic channel thereby (slightly) breaking lepton universality. A possible mixing of the pseudoscalar Higgs and bottomonium resonances is also considered. Finally, several experimental signatures to check out the validity of the conjecture are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0307/0307313v2.pdf"}
{"id": "hep-ph0309055", "abstract": "  The Cornwall-Jackiw-Tomboulis (CJT) effective action for composite operators at finite temperature is used to investigate the chiral phase transition within the framework of the linear sigma model as the low-energy effective model of quantum chromodynamics (QCD). A new renormalization prescription for the CJT effective action in the Hartree-Fock (HF) approximation is proposed. A numerical study, which incorporates both thermal and quantum effect, shows that in this approximation the phase transition is of first order. However, taking into account the higher-loop diagrams contribution the order of phase transition is unchanged. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0309/0309055v1.pdf"}
{"id": "hep-ph0404132", "abstract": "  We study the possible signals of a pion string associated with the QCD chiral phase transition in LHC Pb - Pb collision at energy √(s)=5.5 TeV. In terms of the Kibble-Zurek mechanism we discuss the production and evolution of the pion string. The pion string is not topologically stable, it decays into neutral pions and sigma mesons which in turn decay into pions. Our results show that all the neutral pions from the pion string are distributed at the low momentum and the ratio of neutral to charged pions from the pion string violates the isospin symmetry. For the momentum spectra of the total pions, the signal from the sigma particle decay which is from the pion string will be affected by the large decay width of the sigma significantly. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0404/0404132v3.pdf"}
{"id": "hep-ph0404236", "abstract": "  PHASE is a Monte Carlo event generator, under construction, for all Standard Model processes with six fermions in the final state at the LHC. It employs the full set of tree level Feynman diagrams, taking into account fermion masses for b quarks. The program can generate unweighted events for any subset of all six fermion final states in a single run, by making use of dedicated pre-samples. An interface to hadronization is provided. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0404/0404236v1.pdf"}
{"id": "hep-ph0405258", "abstract": "  We consider the analytical properties of the single-soliton solution in a Skyrmion-type Lagrangian that incorporates the scaling properties of quantum chromodynamics (QCD) through the coupling of the chiral field to a scalar field interpreted as a bound state of gluons. The model was proposed in previous works to describe the Goldstone pions in a dense medium, being also useful for studying the properties of nuclear matter and the in-medium properties of mesons and nucleons. Guided by an asymptotic analysis of the Euler-Lagrange equations, we propose approximate analytical representations for the single soliton solution in terms of rational approximants exponentially localized. Following the Padé method, we construct a sequence of approximants from the exact power series solutions near the origin. We find that the convergence of the approximate representations to the numerical solutions is considerably improved by taking the expansion coefficients as free parameters and then minimizing the mass of the Skyrmion using our ansätze for the fields. We also perform an analysis of convergence by computation of physical quantities showing that the proposed analytical representations are very useful useful for phenomenological calculations. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0405/0405258v2.pdf"}
{"id": "hep-ph0407047", "abstract": "  A neutral vector boson can possess static electromagnetic properties provided that the associated field is no self-conjugate. This possibility is explored in the SU_C(3) X SU_L(3) X U_N(1) model with right-handed neutrinos, which predicts a complex neutral gauge boson Y^0 in a nontrivial representation of the electroweak group. In this model the only nonvanishing form factors are the CP-even ones, which arise from both the quark and gauge sectors, and contribute to the magnetic dipole and the electric quadrupole moments of this neutral particle. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0407/0407047v1.pdf"}
{"id": "hep-ph0408025", "abstract": "  We argue that a systems of tightly knotted, linked, or braided flux tubes will have a universal mass-energy spectrum, since the length of fixed radius flux tubes depend only on the topology of the configuration. We motivate the discussion with plasma physics examples, then concentrate on the model of glueballs as knotted QCD flux tubes. Other applications will also be discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0408/0408025v1.pdf"}
{"id": "hep-ph0502195", "abstract": "  We study the production of a pseudoscalar Higgs boson A^0 in association with a Z^0 boson at a future international linear collider (ILC). We consider the contributions to this process at the one loop level in the Minimal Supersymmetric Standard Model (MSSM) from top and bottom quarks as well as stop and sbottom squarks. We also study the squark contributions to the decay widths of the pseudoscalar Higgs boson for the decays A^0 –> γZ^0and A^0 –> Z^0 Z^0. The contribution from the supersymmetric loops are found to be directly proportional to the squark mixing and potentially large due to the massive pseudoscalar Higgs coupling to squarks.", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0502/0502195v2.pdf"}
{"id": "hep-ph0505003", "abstract": "  We present a simple gluon production picture which is based on the McLerran-Venugopalan model and gluon BFKL evolution in relativistic heavy ion collision. Results for the multiplicity and transverse energy distribution in both the central and forward rapidity regions for gluon production in early stages of heavy ion collisions at the LHC are given. Finally, we provide a general qualitative discussion of the consequences of the forward rapidity behavior of produced gluons. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0505/0505003v2.pdf"}
{"id": "hep-ph0505212", "abstract": "  Plasma instabilities can play a fundamental role in plasma equilibration. There are similarities and differences between plasma instabilities in abelian and non-abelian gauge theories. In particular, it has been an open question whether non-abelian self-interactions are the limiting factor in the growth of non-abelian plasma instabilities. We study this problem with 3+1 dimensional numerical simulations. We find that non-abelian plasma instabilities behave very differently from abelian ones once they grow to be non-perturbatively large, in contrast with earlier results of 1+1 dimensional simulations. In particular, they grow more slowly at late times, with linear rather than exponential dependence of magnetic energy on time. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0505/0505212v2.pdf"}
{"id": "hep-ph0508096", "abstract": "  We review the work discussed and developed under the topic “Resummation” at Working Group 2 “Multijet final states and energy flow”, of the HERA-LHC Workshop. We emphasise the role played by HERA observables in the development of resummation tools via, for instance, the discovery and resummation of non-global logarithms. We describe the event-shapes subsequently developed for hadron colliders and present resummed predictions for the same using the automated resummation program CAESAR. We also point to ongoing studies at HERA which can be of benefit for future measurements at hadron colliders such as the LHC, specifically dijet E_t and angular spectra and the transverse momentum of the Breit current hemisphere. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0508/0508096v1.pdf"}
{"id": "hep-ph0601090", "abstract": "  The flavour-changing neutral current transition b →s can serve as a sensitive probe of WIMP dark matter models, if the WIMP mass is under 2 GeV. In this work we extend our earlier analysis to a generic class of models where the interaction between the dark matter sector and the Standard Model matter sector is mediated by the Higgs boson(s). We show that experimental limits on the decays of B-mesons to K(K^*) and missing energy provide stringent constraints on the parameter space of such models, but do not rule out sub-GeV WIMPs in a model-independent way. We find that in the context of the NMSSM with light pseudoscalar Higgs, the WIMP masses under a few hundred MeV are generically excluded with the exception of few highly tuned points in the parameter space. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0601/0601090v2.pdf"}
{"id": "hep-ph0606248", "abstract": "  We analyze the implications of neutrino masses for the magnitude of neutrino magnetic moments. By considering electroweak radiative corrections to the neutrino mass, we derive model-independent naturalness upper bounds on neutrino magnetic moments, μ_ν, generated by physics above the electroweak scale. For Dirac neutrinos, the bound is several orders of magnitude more stringent than present experimental limits. However, for Majorana neutrinos the magnetic moment contribution to the mass is Yukawa suppressed. The bounds we derive for magnetic moments of Majorana neutrinos are weaker than present experimental limits if μ_ν is generated by new physics at   1 TeV, and surpass current experimental sensitivity only for new physics scales > 10 – 100 TeV. The discovery of a neutrino magnetic moment near present limits would thus signify that neutrinos are Majorana particles. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0606/0606248v2.pdf"}
{"id": "hep-ph0702052", "abstract": "  In view of possible photoproduction studies in ultraperipheral heavy-ion collisions at the LHC, we briefly review the present theoretical understanding of photons and hard photoproduction processes at HERA, discussing the production of jets, light and heavy hadrons, quarkonia, and prompt photons. We address in particular the extraction of the strong coupling constant from photon structure function and inclusive jet measurements, the infrared safety and computing time of jet definitions, the sensitivity of dijet cross sections on the parton densities in the photon, factorization breaking in diffractive dijet production, the treatment of the heavy-quark mass in charm production, the relevance of the color-octet mechanism for quarkonium production, and isolation criteria for prompt photons. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0702/0702052v1.pdf"}
{"id": "hep-ph9412336", "abstract": "  Results on dynamical fluctuations of charged particles in the pseudorapidity space of central C–Cu interactions at 4.5 A GeV/c are performed in the transformed variables and using higher order scaled factorial moments modifyied to remove the bias of infinite statistics in the normalization. The intermittency behavior is found up to eighth order of the moments increasing with the order and leading to the pronounced multifractality. Two differed intermittent-like rises are obtained, one indicating an occurrence of the non-thermal phase transition, and no critical behavior is found to be reached in another case. The observations may be treated to show different regimes of particle production during the cascade. Comparison with some conventional model approximations notes the multiparticle character of the fluctuations. The results presented can be effective in sense of sensitivity of intermittency to the hadronization phase. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9412/9412336v1.pdf"}
{"id": "hep-ph9502365", "abstract": "  Exact mathematical solution of the minimization conditions of scalar the Higgs potential of the Finite Supersymmetric Grand Unification Theory is proposed and extremal field configurations are found. Types of extrema are investigated and masses of the new Higgs particles arisen after electroweak symmetry breaking are derived analytically. The conditions for existing of physically acceptable minimum are given. As it appears, this minimum is simple generalization of the analogous solution in the Minimal Supersymmetric Standard Model. Phenomenological consequences are discussed briefly. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9502/9502365v2.pdf"}
{"id": "hep-ph9511216", "abstract": "  The effect of perturbations of electroweak strings on quark zero modes is studied in 2+1 and 3+1 dimensions. As first discovered by Naculich, it is found that the bosonic perturbations that destabilize the string give a mass to the zero modes and also lift their degeneracy. The effect of the zero modes on the stability of the string is discussed qualitatively and we argue that the fermionic vacuum instability found by Naculich should lead to a distortion of the bosonic string but not be responsible for decay. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9511/9511216v1.pdf"}
{"id": "hep-ph9605378", "abstract": "  We examine the mechanism of gaugino condensation in supersymmetric theories within a Nambu-Jona-Lasinio type approach. We investigate the effective Lagrangian description of higher energy theories that include some moduli fields in the gauge coupling constant. First we consider supersymmetric QCD with and without a mass term. We can find a phase transition in massless theory, but when we add a mass term, such a phase transition disappears. We also examine a model with a dilaton dependent coupling constant and find that it is very similar to supersymmetric QCD. Application of our method to supergravity is also examined. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9605/9605378v2.pdf"}
{"id": "hep-ph9609509", "abstract": "  We present a scenario of neutrino masses and mixing angles. Each generation includes a sterile right handed neutrino in addition to the usual left handed one. We assume a hierarchy in their Dirac masses similar to, but much larger than the hierarchies in the quarks and charged leptons. In addition, we include a Majorana mass term for the sterile neutrinos only. These assumptions prove sufficient to accomodate scales of mass differences and mixing angles consistent with all existing neutrino oscillation data. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9609/9609509v1.pdf"}
{"id": "hep-ph9703360", "abstract": "  The basic box and phase space integrals needed to compute at second order the three-jet decay rate of the Z-boson into massive quarks are presented in this paper. Dimensional Regularization is used to regularize the infrared divergences that appear in intermediate steps. Finally, the cancellation of these divergences among the virtual and the real contributions is showed explicitly. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9703/9703360v2.pdf"}
{"id": "hep-ph9705340", "abstract": "  We study a simplified version of the Standard Electroweak Model and introduce the concept of the physical gauge invariant effective potential in terms of matrix elements of the Hamiltonian in physical states. This procedure allows an unambiguous identification of the symmetry breaking order parameter and the resulting effective potential as the energy in a constrained state. We explicitly compute the physical effective potential at one loop order and improve it using the RG. This construction allows us to extract a reliable, gauge invariant bound on the Higgs mass by unambiguously obtaining the scale at which new physics should emerge to preclude vacuum instability. Comparison is made with popular gauge fixing procedures and an “error” estimate is provided between the Landau gauge fixed and the gauge invariant results. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9705/9705340v1.pdf"}
{"id": "hep-ph9810290", "abstract": "  The calculation of the next-to-leading order SUSY-QCD corrections to the production of squarks, gluinos and gauginos at the Tevatron is reviewed. The NLO corrections stabilize the theoretical predictions of the various production cross sections significantly and lead to sizeable enhancements of the most relevant cross sections for scales near the average mass of the produced massive particles. We discuss the phenomenological consequences of the results on present and future experimental analyses. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9810/9810290v3.pdf"}
{"id": "hep-ph9907322", "abstract": "  Production and equilibration of quark-gluon plasma are studied within the color flux-tube model, at the RHIC and LHC energies. Non-Abelian relativistic transport equations for quarks, antiquarks and gluons, are solved in the extended phase space which includes coordinates, momenta and color. Before the chromoelectric field is formed, hard and semihard partons are produced via minijets which provide the initial conditions necessary to solve the transport equations. The model predicts that in spite of the vast difference between the RHIC and LHC incident energies, once the local equilibrium is reached, the energy densities, the number densities and the temperatures at the two machines may not be very different from each other. The minijet input significantly alters the evolution of the deconfined matter, unless the color field is too strong. For the input parameters used here the equilibration time is estimated to be ∼ 1 fm at RHIC and ∼ 0.5 fm at LHC, measured from the instant when the two colliding nuclei have just passed through each other. The temperature at equilibration is found to be ∼ 250 MeV at RHIC and ∼ 300 MeV at LHC. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9907/9907322v3.pdf"}
{"id": "hep-th0004109", "abstract": "  We show that in brane-world scenarios with warped extra dimensions, the Casimir force due to bulk matter fields may be sufficient to stabilize the radion field ϕ. In particular, we calculate one loop effective potential for ϕ induced by bulk gravitons and other possible massless bulk fields in the Randall-Sundrum background. This potential has a local extremum, which can be a maximum or a minimum depending on the detailed bulk matter content. If the parameters of the background are chosen so that the hierarchy problem is solved geometrically, then the radion mass induced by Casimir corrections is hierarchycally smaller than the TeV. Hence, in this important case, we must invoke an alternative mechanism (classical or nonperturbative) which gives the radion a sizable mass, to make it compatible with observations. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0004/0004109v2.pdf"}
{"id": "hep-th0107073", "abstract": "  A modification of perturbation theory, known as delta-expansion (variationally improved perturbation), gave rigorously convergent series in some D=1 models (oscillator energy levels) with factorially divergent ordinary perturbative expansions. In a generalization of variationally improved perturbation appropriate to renormalizable asymptotically free theories, we show that the large expansion orders of certain physical quantities are similarly improved, and prove the Borel convergence of the corresponding series for m_v  0, with m_v the new (arbitrary) mass perturbation parameter. We argue that non-ambiguous estimates of quantities relevant to dynamical (chiral) symmetry breaking in QCD, are possible in this resummation framework. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0107/0107073v3.pdf"}
{"id": "hep-th0201246", "abstract": "  The question of general covariance in quantum gravity is considered in the first post-Newtonian approximation. Transformation properties of observable quantities under deformations of a reference frame, induced by variations of the gauge conditions fixing general invariance, are determined. It is found that the one-loop contributions violate the principle of general covariance, in the sense that the quantities which are classically invariant under such deformations take generally different values in different reference frames. The relative value of this violation is of the order 1/N, where N is the number of particles in a gravitating body. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0201/0201246v1.pdf"}
{"id": "hep-th0203246", "abstract": "  We find that dilaton dominated supersymmetry breaking and spontaneous CP violation can be achieved in heterotic string models with superpotentials singular at the fixed points of the modular group. A semi–realistic picture of CP violation emerges in such models: the CKM phase appears due to a complex VEV of the T-modulus, while the soft supersymmetric CP phases are absent due to an axionic–type symmetry. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0203/0203246v1.pdf"}
{"id": "hep-th0301169", "abstract": "  In this paper we consider a charged massless scalar quantum field operator in the spacetime of an idealized cosmic string, i.e., an infinitely long, straight and static cosmic string, which presents a magnetic field confined in a cylindrical tube of finite radius. Three distinct situations are taking into account in this analysis: i) a homogeneous field inside the tube, ii) a magnetic field proportional to 1/r and iii) a cylindrical shell with δ-function. In these three cases the axis of the infinitely long tube of radius R coincides with the cosmic string. In order to study the vacuum polarization effects outside the tube, we explicitly calculate the Euclidean Green function associated with this system for the three above situations, considering points in the region outside the tube. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0301/0301169v1.pdf"}
{"id": "hep-th0306081", "abstract": "  We apply the quartic exponential variational approximation to the symmetry breaking phenomena of scalar field in three and four dimensions. We calculate effective potential and effective action for the time-dependent system by separating the zero mode from other non-zero modes of the scalar field and treating the zero mode quantum mechanically. It is shown that the quantum mechanical properties of the zero mode play a non-trivial role in the symmetry breaking of the scalar λϕ^4 theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0306/0306081v1.pdf"}
{"id": "hep-th0307173", "abstract": "  We investigate gauge invariant operators corresponding to on-shell closed string states in open string field theory. Using both oscillator representation and conformal mapping techniques, we calculate a two closed string tachyon amplitude that connects two gauge invariant operators by an open string propagator.We find that this amplitude is in a complete agreement with the usual disc amplitude. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0307/0307173v1.pdf"}
{"id": "hep-th0508167", "abstract": "  We introduce a new mechanism for producing locally stable de-Sitter or Minkowski vacua, with spontaneously broken N=1 supersymmetry and no massless scalars, applicable to superstring and M-theory compactifications with fluxes. We illustrate the mechanism with a simple N=1 supergravity model that provides parametric control on the sign and the size of the vacuum energy. The crucial ingredient is a gauged U(1) that involves both an axionic shift and an R-symmetry, and severely constrains the F- and D-term contributions to the potential. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0508/0508167v3.pdf"}
{"id": "hep-th0509194", "abstract": "  We derive an effective theory describing the physics of a bulk brane in the context of the RS1 model. This theory goes beyond the usual low energy effective theory in that it describes the regime where the bulk brane has a large velocity and the radion can change rapidly. We achieve this by concentrating on the region where the distance between the orbifold planes is small in comparison to the AdS length scale. Consequently our effective theory will describe the physics shortly before a bulk/boundary or boundary/boundary brane collision. We study the cosmological solutions and find that, at large velocities, the bulk brane decouples from the matter on the boundary branes, a result which remains true for cosmological perturbations. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0509/0509194v2.pdf"}
{"id": "hep-th0603244", "abstract": "  We consider the simplest scenario when black strings / cigars penetrate the cosmological brane. As a result, the brane has a Swiss-cheese structure, with Schwarzschild black holes immersed in a Friedmann-Lemaître-Robertson-Walker brane. There is no dark radiation in the model, the cosmological regions of the brane are characterized by a cosmological constant Λ and flat spatial sections. Regardless of the value of Λ, these brane-world universes forever expand and forever decelerate. The totality of source terms in the modified Einstein equation sum up to a dust, establishing a formal equivalence with the general relativistic Einstein-Straus model. However in this brane-world scenario with black strings the evolution of the cosmological fluid strongly depends on Λ. For Λ≤ 0 it has positive energy density ρ and negative pressure p and at late times it behaves as in the Einstein-Straus model. For (not too high) positive values of Λ the cosmological evolution begins with positive ρ and negative p, but this is followed by an epoch with both ρ and p positive. Eventually, ρ becomes negative, while p stays positive. A similar evolution is present for high positive values of Λ, however in this case the evolution ends in a pressure singularity, accompanied by a regular behaviour of the cosmic acceleration. This is a novel type of singularity appearing in brane-worlds. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0603/0603244v2.pdf"}
{"id": "hep-th0604141", "abstract": "  We derive the relation between the Hilbert space of certain geometries under the Bohr-Sommerfeld quantization and the perturbative prepotentials for the supersymmetric five-dimensional SU(N) gauge theories with massive fundamental matters and with one massive adjoint matter. The gauge theory with one adjoint matter shows interesting features. A five-dimensional generalization of Nekrasov's partition function can be written as a correlation function of two-dimensional chiral bosons and as a partition function of a statistical model of partitions. From a ground state of the statistical model we reproduce the polyhedron which characterizes the Hilbert space. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0604/0604141v2.pdf"}
{"id": "hep-th0610243", "abstract": "  Using the exactly solvable Gross-Neveu model as theoretical laboratory, we analyse in detail the relationship between a relativistic quantum field theory at real and imaginary chemical potential. We find that one can retrieve the full information about the phase diagram of the theory from an imaginary chemical potential calculation. The prerequisite is to evaluate and analytically continue the effective potential for the chiral order parameter, rather than thermodynamic observables or phase boundaries. In the case of an inhomogeneous phase, one needs to compute the full effective action, a functional of the space-dependent order parameter, at imaginary chemical potential. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0610/0610243v2.pdf"}
{"id": "hep-th0611155", "abstract": "  We consider different types of external color sources that move through a strongly-coupled thermal N=4 super-Yang-Mills plasma, and calculate, via the AdS/CFT correspondence, the dissipative force (or equivalently, the rate of energy loss) they experience. A bound state of k quarks in the totally antisymmetric representation is found to feel a force with a nontrivial k-dependence. Our result for k=1 (or k=N-1) agrees at large N with the one obtained recently by Herzog et al. and Gubser, but contains in addition an infinite series of 1/N corrections. The baryon (k=N) is seen to experience no drag. Finally, a heavy gluon is found to be subject to a force which at large N is twice as large as the one experienced by a heavy quark, in accordance with gauge theory expectations. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0611/0611155v3.pdf"}
{"id": "hep-th0701054", "abstract": "  We analyze the response of a detector with a uniform acceleration α in κ-Minkowski spacetime using the first order perturbation theory. The monopole detector is coupled to a massless complex scalar field in such a way that it is sensitive to the Lorentz violation due to the noncommutativity of spacetime present in the κ-deformation. The response function deviates from the thermal distribution of Unruh temperature at the order of 1/κ and vanishes exponentially as the proper time of the detector exceeds a certain critical time, a logarithmic function of κ. This suggests that the Unruh temperature becomes not only fuzzy but also eventually decreases to zero in this model. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0701/0701054v1.pdf"}
{"id": "hep-th0701174", "abstract": "  From the quantum field theory point of view, matter and gauge fields are generally expected to be localised around branes or topological defects occurring in extra dimensions. Here I discuss a simple scenario where, by starting with a five dimensional SU(3) gauge theory, we end up with several 4-D parallel branes with localised \"chiral\" fermions and gauge fields to them. I will show that it is possible to reproduce the electroweak model confined to a single brane, allowing a simple and geometrical approach to the fermion hierarchy problem. Some nice results of this construction are: Gauge and Higgs fields are unified at the 5-D level; and new particles are predicted: a left-handed neutrino of zero hypercharge, and a massive vector field coupling together the new neutrino to other left-handed leptons. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0701/0701174v1.pdf"}
{"id": "hep-th9601064", "abstract": "  The question of how to account for the outgoing black hole modes without drawing upon a transplanckian reservoir at the horizon is addressed. It is argued that the outgoing modes must arise via conversion from ingoing modes. It is further argued that the back-reaction must be included to avoid the conclusion that particle creation cannot occur in a strictly stationary background. The process of “mode conversion\" is known in plasma physics by this name and in condensed matter physics as “Andreev reflection\" or “branch conversion\". It is illustrated here in a linear Lorentz non-invariant model introduced by Unruh. The role of interactions and a physical short distance cutoff is then examined in the sonic black hole formed with Helium-II. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/9601/9601064v2.pdf"}
{"id": "hep-th9603161", "abstract": "  We continue our study of compactifications of F-theory on Calabi–Yau threefolds. We gain more insight into F-theory duals of heterotic strings and provide a recipe for building F-theory duals for arbitrary heterotic compactifications on elliptically fibered manifolds. As a byproduct we find that string/string duality in six dimensions gets mapped to fiber/base exchange in F-theory. We also construct a number of new N=1, d=6 examples of F-theory vacua and study transitions among them. We find that some of these transition points correspond upon further compactification to 4 dimensions to transitions through analogues of Argyres–Douglas points of N=2 moduli. A key idea in these transitions is the notion of classifying (0,4) fivebranes of heterotic strings. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/9603/9603161v2.pdf"}
{"id": "hep-th9605174", "abstract": "  We study the internal dynamics of Ramond-Ramond solitons excited far from the BPS limit by leading Regge trajectory open strings. The simplest world volume process for such strings is splitting into two smaller pieces, and we calculate the corresponding decay rates. Compared to the conventional open superstring, the splitting of states polarized parallel to the brane is suppressed by powers of logarithms of the energy. The rate for states polarized transverse to the brane decreases with increasing energy. We also calculate the static force between a D-brane excited by a massive open string and an unexcited D-brane parallel to it. The result shows that transversely polarized massive open strings endow D-branes with a size of order the string scale. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/9605/9605174v1.pdf"}
{"id": "hep-th9609080", "abstract": "  We compute the Form Factors of the relevant scaling operators in a class of integrable models without internal symmetries by exploiting their cluster properties. Their identification is established by computing the corresponding anomalous dimensions by means of Delfino–Simonetti–Cardy sum–rule and further confirmed by comparing some universal ratios of the nearby non–integrable quantum field theories with their independent numerical determination. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/9609/9609080v1.pdf"}
{"id": "hep-th9611171", "abstract": "  We consider branching of baby universes off parent one in (1+1)-dimensional dilaton gravity with 24 types of conformal matter fields. This theory is equivalent to string theory in a certain background in D=26-dimensional target space, so this process may be also viewed as the emission of a light string state by a heavy string. We find that bare energy is not conserved in (1+1) dimensions due to the emission of baby universes, and that the probability of this process is finite even for local distribution of matter in the parent universe. We present a scenario suggesting that the non-conservation of bare energy may be consistent with the locality of the baby universe emission process in (1+1) dimensions and the existence of the long ranged dilaton field whose source is bare energy. This scenario involves the generation of longitudinal gravitational waves in the parent universe. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/9611/9611171v1.pdf"}
{"id": "hep-th9804122", "abstract": "  Chern-Simons theories, which are topological quantum field theories, provide a field theoretic framework for the study of knots and links in three dimensions. These are rare examples of quantum field theories which can be exactly and explicitly solved. Expectation values of Wilson link operators yield a class of link invariants, the simplest of them is the famous Jones polynomial. Other invariants are more powerful than that of Jones. These new invariants are sensitive to the chirality of all knots at least upto ten crossing number unlike those of Jones which are blind to the chirality of some of them. However, all these invariants are still not good enough to distinguish a class of knots called mutants. These link invariants can be alternately obtained from two dimensional vertex models. The R-matrix of such a model in a particular limit of the spectral parameter provides a representation of the braid group. This in turn is used to construct the link invariants. Exploiting theorems of Lickorish and Wallace and also those of Kirby, Fenn and Rourke which relate three-manifolds to surgeries on framed links, these link invariants in S^3 can also be used to construct three-manifold invariants. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/9804/9804122v1.pdf"}
{"id": "math-ph0511084", "abstract": "  The article is devoted to the following question. Consider a periodic self-adjoint difference (differential) operator on a graph (quantum graph) G with a co-compact free action of the integer lattice Z^n. It is known that a local perturbation of the operator might embed an eigenvalue into the continuous spectrum (a feature uncommon for periodic elliptic operators of second order). In all known constructions of such examples, the corresponding eigenfunction is compactly supported. One wonders whether this must always be the case. The paper answers this question affirmatively. What is more surprising, one can estimate that the eigenmode must be localized not far away from the perturbation (in a neighborhood of the perturbation's support, the width of the neighborhood determined by the unperturbed operator only).   The validity of this result requires the condition of irreducibility of the Fermi (Floquet) surface of the periodic operator, which is expected to be satisfied for instance for periodic Schroedinger operators. ", "pdf_url": "gs://arxiv-dataset/arxiv/math-ph/pdf/0511/0511084v1.pdf"}
{"id": "math0005256", "abstract": "  These notes contain a survey of some aspects of the theory of differential modules and complexes as well as of their generalization, that is, the theory of N-differential modules and N-complexes. Several applications and examples coming from physics are discussed. The commun feature of these physical applications is that they deal with the theory of constrained or gauge systems. In particular different aspects of the BRS methods are explained and a detailed account of the N-complexes arising in the theory of higher spin gauge fields is given. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0005/0005256v2.pdf"}
{"id": "math0106076", "abstract": "  We give a formula that expresses the Hilbert series of one-sided ladder determinantal rings, up to a trivial factor, in form of a determinant. This allows the convenient computation of these Hilbert series. The formula follows from a determinantal formula for a generating function for families of nonintersecting lattice paths that stay inside a one-sided ladder-shaped region, in which the paths are counted with respect to turns. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0106/0106076v3.pdf"}
{"id": "math0112209", "abstract": "  Rozansky and Witten proposed in 1996 a family of new three-dimensional topological quantum field theories, indexed by compact (or asymptotically flat) hyperkaehler manifolds. As a byproduct they proved that hyperkaehler manifolds also give rise to Vassiliev weight systems. These may be thought of as invariants of hyperkaehler manifolds, so the theory is of interest to geometers as well as to low-dimensional topologists. This paper surveys the geometrical construction of the weight systems, how they may be integrated into the framework of Lie algebra weight systems (joint work with Simon Willerton), their applications, and an approach to a rigorous construction of the TQFTs (joint work with Justin Sawon and Simon Willerton). ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0112/0112209v1.pdf"}
{"id": "math0407068", "abstract": "  Differential graded algebra invariants are constructed for Legendrian links in the 1-jet space of the circle. In parallel to the theory for R^3, Poincare-Chekanov polynomials and characteristic algebras can be associated to such links. The theory is applied to distinguish various knots, as well as links that are closures of Legendrian versions of rational tangles. For a large number of two-component links, the Poincare-Chekanov polynomials agree with the polynomials defined through the theory of generating functions. Examples are given of knots and links which differ by an even number of horizontal flypes that have the same polynomials but distinct characteristic algebras. Results obtainable from a Legendrian satellite construction are compared to results obtainable from the DGA and generating function techniques. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0407/0407068v2.pdf"}
{"id": "math0510638", "abstract": "  The problem of image reconstruction in thermoacoustic tomography requires inversion of a generalized Radon transform, which integrates the unknown function over circles in 2D or spheres in 3D. The paper investigates implementation of the recently discovered backprojection type inversion formulas for the case of spherical acquisition in 3D. A numerical simulation of the data acquisition with subsequent reconstructions are made for the Defrise phantom as well as for some other phantoms. Both full and partial scan situations are considered. The results are compared with the implementation of a previously used approximate inversion formula. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0510/0510638v1.pdf"}
{"id": "math0605345", "abstract": "  Tropical geometry yields good lower bounds, in terms of certain combinatorial-polyhedral optimisation problems, on the dimensions of secant varieties. In particular, it gives an attractive pictorial proof of the theorem of Hirschowitz that all Veronese embeddings of the projective plane except for the quadratic one and the quartic one are non-defective; this proof might be generalisable to cover all Veronese embeddings, whose secant dimensions are known from the ground-breaking but difficult work of Alexander and Hirschowitz. Also, the non-defectiveness of certain Segre embeddings is proved, which cannot be proved with the rook covering argument already known in the literature. Short self-contained introductions to secant varieties and the required tropical geometry are included. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0605/0605345v3.pdf"}
{"id": "math0606700", "abstract": "  We discover suprising connections between three seemingly different problems: finding right triangles with rational sides in a non-Euclidean geometry, finding three integers such that the difference of the squares of any two is a square, and the problem of finding rational points on an algebraic surface in algebraic geometry. We will also reinterpret Euler's work on the second problem with a modern point of view. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0606/0606700v1.pdf"}
{"id": "math0610925", "abstract": "  In this paper we consider faultfree tromino tilings of rectangles and characterize rectangles that admit such tilings. We introduce the notion of crossing numbers for tilings and derive bounds on the crossing numbers of faultfree tilings. We develop an iterative scheme for generating faultfree tromino tilings for rectangles and derive the closed form expression for the exact number of faultfree tromino tilings for 4×3t rectangles and the exact generating function for 5× 3t rectangles, t≥ 1. Our iterative scheme generalizes to arbitrary rectangles; for 6× 6t and 7× 6t rectangles, t≥ 1, we derive generating functions for estimating lower bounds on the number of faultfree tilings. We also derive an upper bound on the number of tromino tilings of an m× n rectangle, where 3|mn and m,n>0. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0610/0610925v1.pdf"}
{"id": "math0612475", "abstract": "  The notion of a topological Jordan decomposition of a compact element of a reductive p-adic group has proven useful in many contexts. In this paper, we generalise it to groups defined over fairly general discretely-valued fields and prove the usual existence and uniqueness properties, as well as an analogue of a fixed-point result of Prasad and Yu. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0612/0612475v2.pdf"}
{"id": "math9909150", "abstract": "  The paper concerns discrete versions of the three well-known results of projective differential geometry: the four vertex theorem, the six affine vertex theorem and the Ghys theorem on four zeroes of the Schwarzian derivative. We study geometry of closed polygonal lines in ^d and prove that polygons satisfying a certain convexity condition have at least d+1 flattenings. This result provides a new approach to the above mentioned classical theorems. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/9909/9909150v1.pdf"}
{"id": "nlin0103014", "abstract": "  Very narrow spatial bright solitons in (1+1)D and (2+1)D versions of cubic-quintic and full saturable models are studied, starting from the full system of the Maxwell's equations, rather than from the paraxial (NLS) approximation. For the solitons with both TE and TM polarizations, it is shown that there always exists a finite minimum width, and they cease to exist at a critical value of the propagation constant, at which their width diverges. Full similarity of the results obtained for both nonlinearities suggests that the same general conclusions apply to narrow solitons in any non-Kerr model. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0103/0103014v1.pdf"}
{"id": "nlin0110044", "abstract": "  A generalized Kuramoto model of coupled phase oscillators with slowly varying coupling matrix is studied. The dynamics of the coupling coefficients is driven by the phase difference of pairs of oscillators in such a way that the coupling strengthens for synchronized oscillators and weakens for non-synchronized pairs. The system possesses a family of stable solutions corresponding to synchronized clusters of different sizes. A particular cluster can be formed by applying external driving at a given frequency to a group of oscillators. Once established, the synchronized state is robust against noise and small variations in natural frequencies. The phase differences between oscillators within the synchronized cluster can be used for information storage and retrieval. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0110/0110044v1.pdf"}
{"id": "nlin0204052", "abstract": "  We study the singular effects of vanishingly small surface tension on the dynamics of finger competition in the Saffman-Taylor problem, using the asymptotic techniques described in [S. Tanveer, Phil. Trans. R. Soc. Lond. A 343, 155 (1993)]and [M. Siegel, and S. Tanveer, Phys. Rev. Lett. 76, 419 (1996)] as well as direct numerical computation, following the numerical scheme of [T. Hou, J. Lowengrub, and M. Shelley,J. Comp. Phys. 114, 312 (1994)]. We demonstrate the dramatic effects of small surface tension on the late time evolution of two-finger configurations with respect to exact (non-singular) zero surface tension solutions. The effect is present even when the relevant zero surface tension solution has asymptotic behavior consistent with selection theory.Such singular effects therefore cannot be traced back to steady state selection theory, and imply a drastic global change in the structure of phase-space flow. They can be interpreted in the framework of a recently introduced dynamical solvability scenario according to which surface tension unfolds the structually unstable flow, restoring the hyperbolicity of multifinger fixed points. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0204/0204052v1.pdf"}
{"id": "nlin0209032", "abstract": "  In systems with few degrees of freedom modern quantum calculations are, in general, numerically more efficient than semiclassical methods. However, this situation can be reversed with increasing dimension of the problem. For a three-dimensional system, viz. the hyperbolic four-sphere scattering system, we demonstrate the superiority of semiclassical versus quantum calculations. Semiclassical resonances can easily be obtained even in energy regions which are unattainable with the currently available quantum techniques. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0209/0209032v1.pdf"}
{"id": "nlin0306019", "abstract": "  We study numerically the mechanical stability and elasticity properties of duplex DNA molecules within the frame of a network model incorporating microscopic degrees of freedom related with the arrangement of the base pairs. We pay special attention to the opening-closing dynamics of double-stranded DNA molecules which are forced into non-equilibrium conformations. Mechanical stress imposed at one terminal end of the DNA molecule brings it into a partially opened configuration. We examine the subsequent relaxation dynamics connected with energy exchange processes between the various degrees of freedom and structural rearrangements leading to complete recombination to the double-stranded conformation. The similarities and differences between the relaxation dynamics for a planar ladder-like DNA molecule and a twisted one are discussed in detail. In this way we show that the attainment of a quasi-equilibrium regime proceeds faster in the case of the twisted DNA form than for its thus less flexible ladder counterpart. Furthermore we find that the velocity of the complete recombination of the DNA molecule is lower than the velocity imposed by the forcing unit which is in compliance with the experimental observations for the opening-closing cycle of DNA molecules. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0306/0306019v1.pdf"}
{"id": "nlin0311021", "abstract": "  A genuinely three-dimensional system, viz. the hyperbolic 4-sphere scattering system, is investigated with classical, semiclassical, and quantum mechanical methods at various center-to-center separations of the spheres. The efficiency and scaling properties of the computations are discussed by comparisons to the two-dimensional 3-disk system. While in systems with few degrees of freedom modern quantum calculations are, in general, numerically more efficient than semiclassical methods, this situation can be reversed with increasing dimension of the problem. For the 4-sphere system with large separations between the spheres, we demonstrate the superiority of semiclassical versus quantum calculations, i.e., semiclassical resonances can easily be obtained even in energy regions which are unattainable with the currently available quantum techniques. The 4-sphere system with touching spheres is a challenging problem for both quantum and semiclassical techniques. Here, semiclassical resonances are obtained via harmonic inversion of a cross-correlated periodic orbit signal. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0311/0311021v1.pdf"}
{"id": "nlin0506039", "abstract": "  We carry out a detailed numerical investigation of stochastic resonance in underdamped systems in the non-perturbative regime. We point out that an important distinction between stochastic resonance in overdamped and underdamped systems lies in the lack of dependence of the amplitude of the noise-averaged trajectory on the noise strength, in the latter case. We provide qualitative explanations for the observed behavior and show that signatures such as the initial decay and long-time oscillatory behaviour of the temporal correlation function and peaks in the noise and phase averaged power spectral density, clearly indicate the manifestation of resonant behaviour in noisy, underdamped bistable systems in the weak to moderate noise regime. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0506/0506039v1.pdf"}
{"id": "nlin0509053", "abstract": "  Amplitude death can occur in chaotic dynamical systems with time-delay coupling, similar to the case of coupled limit cycles. The coupling leads to stabilization of fixed points of the subsystems. This phenomenon is quite general, and occurs for identical as well as nonidentical coupled chaotic systems. Using the Lorenz and Rössler chaotic oscillators to construct representative systems, various possible transitions from chaotic dynamics to fixed points are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0509/0509053v1.pdf"}
{"id": "nucl-ex0104020", "abstract": "  First identical-pion correlations measured at RHIC energies by PHENIX are presented. Two analyses with separate detectors, systematics, and statistics provide consistent results. The resulting HBT radii are moderately larger than those measured at lower energies. The k_t dependence of the Bertsch-Pratt HBT radii is also similar to previous measures and is consistent with the conjecture of an expanding source. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/0104/0104020v1.pdf"}
{"id": "nucl-ex0510024", "abstract": "  A novel Hadron Blind Detector (HBD) has been developed for an upgrade of the PHENIX experiment at RHIC. The HBD will allow a precise measurement of electron-positron pairs from the decay of the light vector mesons and the low-mass pair continuum in heavy-ion collisions. The detector consists of a 50 cm long radiator filled with pure CF4 and directly coupled in a windowless configuration to a triple Gas Electron Multiplier (GEM) detector with a CsI photocathode evaporated on the top face of the first GEM foil. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/0510/0510024v1.pdf"}
{"id": "nucl-ex0609036", "abstract": "  Heavy flavor production in hadronic collisions is dominated by gluonic processes and so is a sensitive probe of the gluon structure function in the nucleon and its modification in nuclei. A study of heavy flavor production in p+p and d+Au collisions in various kinematic regions presents an opportunity to probe cold nuclear medium effects; parton shadowing, color glass condensate, initial state energy loss, and coherent multiple scattering in final state interactions. The PHENIX muon arms cover both forward and backward directions in the rapidity range of 1.2 < |η| < 2.4. We investigate single muon production from open heavy flavor and light mesons decay in p+p and d+Au collisions at forward and backward rapidity. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/0609/0609036v1.pdf"}
{"id": "nucl-ex0612025", "abstract": "  The project to upgrade the CEBAF accelerator at Jefferson Lab to 12 GeV is presented. Most of the research program supporting that upgrade, will require a highly polarized beam, as will be illustrated by a few selected examples. To carry out that research program will require an extensively upgraded instrumentation in two of the existing experimental halls and the addition of a fourth hall. The plans for a high-luminosity electron-ion collider are briefly discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/0612/0612025v1.pdf"}
{"id": "nucl-ex0701033", "abstract": "  The NA60 experiment has studied J/ψ production in Indium-Indium collisions at 158 A·GeV. In this paper we present an updated set of results obtained with the complete set of available statistics and an improved alignment of the vertex tracker. The centrality dependence of the J/ψ production, obtained with an analysis technique based only on the J/ψ sample, indicates that a suppression beyond that induced by nuclear absorption is present in In-In collisions, setting in at ∼80 participant nucleons. A first study of the systematic errors related with this measurement is discussed. We also present preliminary results on the J/ψ azimuthal distributions. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/0701/0701033v1.pdf"}
{"id": "nucl-th0009084", "abstract": "  For pedagogical reasons we compute the caloric curve for 11 particles in a 3^3 lattice. Monte-Carlo simulation can be avoided and exact results are obtained. There is no back-bending in the caloric curve and negative specific heat does not appear. We point out that the introduction of kinetic energy in the nuclear Lattice Gas Model modifies the results of the standard Lattice Gas Model in a profound way. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0009/0009084v1.pdf"}
{"id": "nucl-th0105028", "abstract": "  The axial form factor G_A of the nucleon is investigated for the Goldstone-boson-exchange constituent quark model using the point-form approach to relativistic quantum mechanics. The results, being covariant, show large contributions from relativistic boost effects. The predictions are obtained directly from the quark-model wave functions, without any further input such as vertex or constituent-quark form factors, and fall remarkably close to the available experimental data. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0105/0105028v3.pdf"}
{"id": "nucl-th0212065", "abstract": "  In this paper an equation of state of neutron star matter which includes strange baryons in the framework of Zimanyi and Moszkowski (ZM) model has been obtained. We concentrate on the effects of the isospin dependence of the equation of state constructing for the appropriate choices of parameters the hyperons star model. Numerous neutron star models show that the appearance of hyperons is connected with the increasing density in neutron star interiors. Various studies have indicated that the inclusion of delta meson mainly affects the symmetry energy and through this the chemical composition of a neutron star. As the effective nucleon mass contributes to hadron chemical potentials it alters the chemical composition of the star. In the result the obtained model of the star not only excludes large population of hadrons but also does not reduce significantly lepton contents in the star interior. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0212/0212065v1.pdf"}
{"id": "nucl-th0311100", "abstract": "  The use of Heavy Quark Symmetry to study bottom and charmed baryons leads to important simplifications of the non-relativistic three body problem, which turns out to be easily solved by a simple variational ansatz. Our simple scheme reproduces previous results (baryon masses, charge and mass radii, ...) obtained by solving the Faddeev equations with simple non-relativistic quark–quark potentials, adjusted to the light and heavy–light meson spectra. Wave functions, parameterized in a simple manner, are also given and thus they can be easily used to compute further observables. Our method has been also used to find the predictions for strangeness-less baryons of the SU(2) chirally inspired quark-quark interactions. We find that the one pion exchange term of the chirally inspired interactions leads to relative changes of the Λ_b and Λ_c binding energies as large as 90", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0311/0311100v2.pdf"}
{"id": "nucl-th0402061", "abstract": "  The STAR collaboration at RHIC is measuring the production of electron-positron pairs at small impact parameters, larger than but already close to the range, where the ions interact strongly with each other. We calculate the total cross section, as well as, differential distributions of the pair production process with the electromagnetic excitation of both ions in a semiclassical approach and within a lowest order QED calculation. We compare the distribution of electron and positron with the one coming from the cross section calculation without restriction on impact parameter. Finally we give an outlook of possible results at the LHC. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0402/0402061v1.pdf"}
{"id": "nucl-th0610034", "abstract": "  We study a relation between nuclear forces based on phenomenological approach (V_ph) and nuclear effective field theory (V_EFT) from a viewpoint of renormalization group. We find the relation between these two types of nuclear force using Wilsonian renormalization group equation. Considering the fact that V_EFT is defined in a certain small model space, we show that a simple contact interaction accurately simulates short-distance physics, and that V_EFT is free from dependence on modelling the details of the short-distance physics. Based on our result, we discuss some features of nuclear effective field theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0610/0610034v1.pdf"}
{"id": "nucl-th9402025", "abstract": "  The momentum dependence of the mean-field contribution to the real part of the optical model potential is investigated employing realistic nucleon-nucleon interactions. Within a non-relativistic approach a momentum dependence originates from the non-locality of the Fock exchange term. Deducing the real part of the optical model from a relativistic Dirac Brueckner Hartree Fock approximation for the self-energy of the nucleons yields an additional momentum dependence originating from the non-relativistic reduction of the self-energy. It is demonstrated that large Fock terms are required in the non-relativistic approach to simulate these relativistic features. A comparison is made between a local density approximation for the optical model and a direct evaluation in finite nuclei. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/9402/9402025v1.pdf"}
{"id": "nucl-th9703036", "abstract": "  For deuteron electroweak disintegration, parity violating effects are investigated which arise from the interference of γ and Z exchange as well as from the hadronic sector via a small parity violating component in the deuteron. The general formalism for the differential cross section and polarization observables of electromagnetic deuteron disintegration is extended to incorporate parity violating contributions. Formal expressions for the additional structure functions are derived. Results are presented for these parity violating structure functions for quasifree kinematics neglecting final state interaction and two-body effects. Both types of parity violating contributions to the asymmetry of the inclusive reaction with respect to longitudinally polarized electrons are evaluated. The one from parity violating deuteron components is negligible over the whole range of momentum transfers considered. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/9703/9703036v2.pdf"}
{"id": "nucl-th9704022", "abstract": "  The radiative pion capture process in nuclei is approached by using a continuum shell-model description of the nucleus, together with a phenomenological treatment of the two particle-two hole effects. It is found that these effects play an important role to reproduce the observed experimental photon energy distribution. This distribution as well as the integrated one depends significantly on the details of the mean field potential. This makes this process interesting to investigate the nuclear structure dynamics. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/9704/9704022v1.pdf"}
{"id": "nucl-th9705030", "abstract": "  We study the short-range nucleon-nucleon interaction in a chiral constituent quark model by diagonalizing a Hamiltonian comprising a linear confinement and a Goldstone boson exchange interaction between quarks. The six-quark harmonic oscillator basis contains up to two excitation quanta. We show that the highly dominant configuration is | s^4p^2[42]_O [51]_FS> due to its specific flavour-spin symmetry. Using the Born-Oppenheimer approximation we find a strong effective repulsion at zero separation between nucleons in both ^3S_1 and ^1S_0 channels. The symmetry structure of the highly dominant configuration implies the existence of a node in the S-wave relative motion wave function at short distances. The amplitude of the oscillation of the wave function at short range will be however strongly suppressed. We discuss the mechanism leading to the effective short-range repulsion within the chiral constituent quark model as compared to that related with the one-gluon exchange interaction. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/9705/9705030v1.pdf"}
{"id": "nucl-th9803059", "abstract": "  Dilepton spectra from the decay of phi mesons produced in heavy-ion collisions at SIS/GSI energies (∼ 2 GeV/nucleon) are studied in the relativistic transport model. We include phi mesons produced from baryon-baryon, pion-baryon, and kaon-antikaon collisions. The cross sections for the first two processes are obtained from an one-boson-exchange model, while that for the last process is taken to be the Breit-Wigner form through the phi meson resonance. For dileptons with invariant mass near the phi meson peak, we also include contributions from neutron-proton bremsstrahlung, pion-pion annihilation, and the decay of rho and omega mesons produced in baryon-baryon and meson-baryon collisions. Effects due to medium modifications of the kaon and vector (rho, omega and phi) meson properties are investigated. We find that the kaon medium effects lead to a broadening of the dilepton spectrum as a result of the increase of phi meson decay width. Furthermore, the dropping of phi meson mass in nuclear medium leads to a shoulder structure in the dilepton spectrum besides the main peak at the bare phi meson mass. The experimental measurement of the dilepton spectra from heavy-ion collisions is expected to provide useful information about the phi meson properties in dense matter. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/9803/9803059v1.pdf"}
{"id": "physics0003009", "abstract": "  Small-scale oceanic motions, in combination with bottom topography, induce mean large-scale along-isobaths flows. The direction of these mean flows is usually found to be anticyclonic (cyclonic) over bumps (depressions). Here we employ a quasigeostrophic model to show that the current direction of these topographically induced large-scale flows can be reversed by the small-scale variability. This result addresses the existence of a new bulk effect from the small-scale activity that could have strong consequences on the circulation of the world's ocean. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0003/0003009v1.pdf"}
{"id": "physics0012012", "abstract": "  The quantum dynamics of coupled subsystems connected to a thermal bath is studied. In some of the earlier work the effect of intercenter coupling on the dissipative part was neglected. This is equivalent to a zeroth-order perturbative expansion of the damping term with respect to the intercenter coupling. It is shown numerically for two coupled harmonic oscillators that this treatment can lead to artifacts and a completely wrong description, for example, of a charge transfer processes even for very weak intercenter coupling. Here we perform a first-order treatment and show that these artifacts disappear. In addition, we demonstrate that the thermodynamic equilibrium population is almost reached even for strong intercenter coupling strength. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0012/0012012v1.pdf"}
{"id": "physics0012050", "abstract": "  Silicon pixel detectors developed to meet LHC requirements were tested in a beam at CERN in the framework of the ATLAS collaboration. The experimental behaviour of irradiated and not-irradiated sensors in a magnetic field is discussed. The measurement of the Lorentz angle for these sensors at different operating conditions is presented. A simple model of the charge drift in silicon before and after irradiation is presented. The good agreement between the model predictions and the experimental results is shown. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0012/0012050v1.pdf"}
{"id": "physics0110013", "abstract": "  The internal energy of high-density hydrogen plasmas in the temperature range T = 10,000 ... 50,000 K is calculated by two different analytical approximation schemes (method of effective ion-ion interaction potential - EIIP and Padé approach within the chemical picture - PACH) and compared with path integral Monte Carlo results. Reasonable agreement between the results obtained from the three independent calculations is found, the reasons for still existing differences is investigated. Interesting high density phenomena such as the formation of clusters and the onset of crystallization are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0110/0110013v1.pdf"}
{"id": "physics0212062", "abstract": "  The photoabsorption spectra of calcium-doped argon clusters CaAr_n are investigated at thermal equilibrium using a variety of theoretical and numerical tools. The influence of temperature on the absorption spectra is estimated using the quantum superposition method for a variety of cluster sizes in the range 6<=n<=146. At the harmonic level of approximation, the absorption intensity is calculated through an extension of the Gaussian theory by Wadi and Pollak [J. Chem. Phys. vol 110, 11890 (1999)]. This theory is tested on simple, few-atom systems in both the classical and quantum regimes for which highly accurate Monte Carlo data can be obtained. By incorporating quantum anharmonic corrections to the partition functions and respective weights of the isomers, we show that the superposition method can correctly describe the finite-temperature spectroscopic properties of CaAr_n systems. The use of the absorption spectrum as a possible probe of isomerization or phase changes in the argon cluster is discussed at the light of finite-size effects. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0212/0212062v1.pdf"}
{"id": "physics0212074", "abstract": "  Solvation free energy is an important quantity in Computational Chemistry with a variety of applications, especially in drug discovery and design. The accurate prediction of solvation free energies of small molecules in water is still a largely unsolved problem, which is mainly due to the complex nature of the water-solute interactions. In this letter we develop a scheme for the determination of the electrostatic contribution to the solvation free energy of charged molecules based on nonlocal electrostatics involving a minimal parameter set which in particular allows to introduce atomic radii in a consistent way. We test our approach on simple ions and small molecules for which both experimental results and other theoretical descriptions are available for quantitative comparison. We conclude that our approach is both physically transparent and quantitatively reliable. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0212/0212074v2.pdf"}
{"id": "physics0306065", "abstract": "  We examine the dependence of the physical quantities of the rotatory molecular motor, such as the rotation velocity and the proton translocation rate, on the chemical reaction rate using the model based only on diffusion process. A peculiar behavior of proton translocation is found and the energy transduction efficiency of the motor protein is enhanced by this behavior. We give a natural explanation that this behavior is universal when certain inequalities between chemical reaction rates hold. That may give a clue to examine whether the motion of the molecular motor is dominated by diffusion process or not. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0306/0306065v2.pdf"}
{"id": "physics0306112", "abstract": "  CDF II is one of the two large collider experiments at Fermilab's Tevatron. Over the past two years we have commissioned the offline computing system. A task that has involved bringing up hundreds of computers and millions of lines of C++ software. This paper reports on this experience, concentrating on the software aspects of the project. We will highlight some of the successes as well as describe some of the work still to do. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0306/0306112v1.pdf"}
{"id": "physics0411054", "abstract": "  Photon–photon scattering in vacuum due to the interaction with virtual electron-positron pairs is a consequence of quantum electrodynamics. A way for detecting this phenomenon has been devised based on interacting modes generated in microwave waveguides or cavities [G. Brodin, M. Marklund and L. Stenflo, Phys. Rev. Lett. 87 171801 (2001)]. Here we materialize these ideas, suggest a concrete cavity geometry, make quantitative estimates and propose experimental details. It is found that detection of photon-photon scattering can be within the reach of present day technology. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0411/0411054v1.pdf"}
{"id": "physics0507086", "abstract": "  Evolution equations for the orientation distribution of axisymmetric particles in periodic flows are derived in the regime of small but non-zero Brownian rotations. The equations are based on a multiple time scale approach that allows fast computation of the relaxation processes leading to statistical equilibrium. The approach has been applied to the calculation of the effective viscosity of a thin disk suspension in gravity waves. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0507/0507086v2.pdf"}
{"id": "physics0601158", "abstract": "  We consider the average probability X of being informed on a gossip in a given social network. The network is modeled within the random graph theory of Erdos and Renyi. In this theory, a network is characterized by two parameters: the size N and the link probability p. Our experimental data suggest three levels of social inclusion of friendship. The critical value p_c, for which half of agents are informed, scales with the system size as N^-γ with γ≈0.68. Computer simulations show that the probability X varies with p as a sigmoidal curve. Influence of the correlations between neighbors is also evaluated: with increasing clustering coefficient C, X decreases. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0601/0601158v3.pdf"}
{"id": "physics0603050", "abstract": "  Quasiclassical approach and geometric optics allow to describe rather accurately whispering gallery modes in convex axisymmetric bodies. Using this approach we obtain practical formulas for the calculation of eigenfrequencies and radiative Q-factors in dielectrical spheroid and compare them with the known solutions for the particular cases and with numerical calculations. We show how geometrical interpretation allows expansion of the method on arbitrary shaped axisymmetric bodies. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0603/0603050v1.pdf"}
{"id": "physics0611299", "abstract": "  This note describes R   D to be carried out on the data acquisition system for a calorimeter at the future International Linear Collider. A generic calorimeter and data acquisition system is described. Within this framework modified designs and potential bottlenecks within the current system are described. Solutions leading up to a technical design report will to be carried out within CALICE-UK groups. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0611/0611299v1.pdf"}
{"id": "physics0612051", "abstract": "  ACORDE, the ALICE COsmic Ray DEtector is one of the ALICE detectors, presently under construction. It consists of an array of plastic scintillator counters placed on the three upper faces of the ALICE magnet. This array will act as Level 0 cosmic ray trigger and, together with other ALICE sub-detectors, will provide precise information on cosmic rays with primary energies around 10^15-17 eV. In this paper we will describe the ACORDE detector, trigger design and electronics. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0612/0612051v1.pdf"}
{"id": "physics0701001", "abstract": "  Measurements with a bare p-type high purity germanium diode (HPGe) submerged in a 19 kg liquid argon (LAr) scintillation detector at MPIK Heidelberg are reported. The liquid argon–germanium system (LArGe) is operated as a 4π anti-Compton spectrometer to suppress backgrounds in the HPGe. This R   D is carried out in the framework of the GERDA experiment which searches for 0νββ decays with HPGe detectors enriched in ^76Ge. The goal of this work is to develop a novel method to discriminate backgrounds in 0νββ search which would ultimately allow to investigate the effective neutrino mass free of background events down to the inverse mass hierarchy scale. Other applications in low-background counting are expected. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0701/0701001v1.pdf"}
{"id": "physics0701124", "abstract": "  The strong influence of the electron dynamics provides the possibility of controlling the expansion of laser-produced plasmas by appropriately shaping the laser pulse. A simple irradiation scheme is proposed to tailor the explosion of large deuterium clusters, inducing the formation of shock structures, capable of driving nuclear fusion reactions. Such a scenario has been thoroughly investigated, resorting to two- and three-dimensional particle-in-cell simulations. Furthermore, the intricate dynamics of ions and electrons during the collisionless expansion of spherical nanoplasmas has been analyzed in detail using a self-consistent ergodic-kinetic model. This study clarifies the transition from hydrodynamic-like to Coulomb-explosion regimes. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0701/0701124v1.pdf"}
{"id": "physics0701215", "abstract": "  The starting point is the problem of finding the interaction energy of two coinciding homogeneous cubic charge distributions. The brute force method of subdividing the cube into N^3 sub-cubes and doing the sums results in slow convergence because of the Coulomb singularity. Using symmetry and algebra the Coulomb singularities can be eliminated. This leads to an accurate numerical algorithm as well as an interesting exact result relating the desired interaction energy to three other interaction energies, namely those of cubes touching each other at a face, at an edge, and at a corner, respectively. As an application a simple model illustrating Wigner crystallization is presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0701/0701215v1.pdf"}
{"id": "physics0702202", "abstract": "  We consider navigation or search schemes on networks which are realistic in the sense that not all search chains can be completed. We show that the quantity μ = ρ/s_d, where s_d is the average dynamic shortest distance and ρ the success rate of completion of a search, is a consistent measure for the quality of a search strategy. Taking the example of realistic searches on scale-free networks, we find that μ scales with the system size N as N^-δ, where δ decreases as the searching strategy is improved.   This measure is also shown to be sensitive to the distintinguishing characteristics of networks. In this new approach, a dynamic small world (DSW) effect is said to exist when δ≈ 0. We show that such a DSW indeed exists in social networks in which the linking probability is dependent on social distances. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0702/0702202v2.pdf"}
{"id": "physics9611019", "abstract": "  We create a dark optical lattice structure using a blue detuned laser field coupling an atomic ground state of total angular momentum F simultaneously to two excited states with angular momenta F and F-1, or F and F+1. The atoms are trapped at locations of purely circular polarization. The cooling process efficiently accumulates almost half of the atomic population in the lowest energy band which is only weakly coupled to the light field. The populations of the two lowest energy bands reaches 70", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/9611/9611019v1.pdf"}
{"id": "q-alg9604014", "abstract": "  Let M be a compact orientable 3-manifold. The set of characters of SL_2(ℂ) representations of the fundamental group of M forms a closed affine algebraic set. We show that its coordinate ring is isomorphic to a specialization of the Kauffman bracket skein module modulo its nilradical. This is accomplished by making the module into a combinatorial analog of the ring, in which tools of skein theory are exploited to illuminate relations among characters. We conclude with an application, proving that a small manifold's specialized module is necessarily finite dimensional. ", "pdf_url": "gs://arxiv-dataset/arxiv/q-alg/pdf/9604/9604014v1.pdf"}
{"id": "q-bio0407020", "abstract": "  We study the spread of Hantavirus over a host population of deer mice using a population dynamics model. We show that taking into account the internal fluctuations in the mouse population due to its discrete character strongly alters the behaviour of the system. In addition to the familiar transition present in the deterministic model, the inclusion of internal fluctuations leads to the emergence of an additional deterministically hidden transition. We determine parameter values that lead to maximal propagation of the disease, and discuss some implications for disease prevention policies. ", "pdf_url": "gs://arxiv-dataset/arxiv/q-bio/pdf/0407/0407020v1.pdf"}
{"id": "q-bio0502005", "abstract": "  A population of complete subgraphs or cliques in a network evolving via duplication-divergence is considered. We find that a number of cliques of each size scales linearly with the size of the network. We also derive a clique population distribution that is in perfect agreement with both the simulation results and the clique statistic of the protein-protein binding network of the fruit fly. In addition, we show that such features as fat-tail degree distribution, various rates of average degree growth and non-averaging, revealed recently for only the particular case of a completely asymmetric divergence, are present in a general case of arbitrary divergence. ", "pdf_url": "gs://arxiv-dataset/arxiv/q-bio/pdf/0502/0502005v1.pdf"}
{"id": "q-bio0605001", "abstract": "  I study the spreading of infectious diseases on heterogeneous populations. I represent the population structure by a contact-graph where vertices represent agents and edges represent disease transmission channels among them. The population heterogeneity is taken into account by the agent's subdivision in types and the mixing matrix among them. I introduce a type-network representation for the mixing matrix allowing an intuitive understanding of the mixing patterns and the analytical calculations. Using an iterative approach I obtain recursive equations for the probability distribution of the outbreak size as a function of time. I demonstrate that the expected outbreak size and its progression in time are determined by the largest eigenvalue of the reproductive number matrix and the characteristic distance between agents on the contact-graph. Finally, I discuss the impact of intervention strategies to halt epidemic outbreaks. This work provides both a qualitative understanding and tools to obtain quantitative predictions for the spreading dynamics on heterogeneous populations. ", "pdf_url": "gs://arxiv-dataset/arxiv/q-bio/pdf/0605/0605001v1.pdf"}
{"id": "q-bio0607029", "abstract": "  We show, that the specific distribution of gene's length, which is observed in natural genomes, might be a result of a growth process, in which a single length scale L(t) develops that grows with time as t^1/3. This length scale could be associated with the length of the longest gene in an evolving genome. The growth kinetics of the genes resembles the one observed in physical systems with conserved ordered parameter. We show, that in genome this conservation is guaranteed by compositional compensation along DNA strands of the purine-like trends introduced by genes. The presented mathematical model is the modified Bak-Sneppen model of critical self-organization applied to the one-dimensional system of N spins. The spins take discrete values, which represent gene's length. ", "pdf_url": "gs://arxiv-dataset/arxiv/q-bio/pdf/0607/0607029v1.pdf"}
{"id": "quant-ph0002037", "abstract": "  Replication of DNA and synthesis of proteins are studied from the view-point of quantum database search. Identification of a base-pairing with a quantum query gives a natural (and first ever) explanation of why living organisms have 4 nucleotide bases and 20 amino acids. It is amazing that these numbers arise as solutions to an optimisation problem. Components of the DNA structure which implement Grover's algorithm are identified, and a physical scenario is presented for the execution of the quantum algorithm. It is proposed that enzymes play a crucial role in maintaining quantum coherence of the process. Experimental tests that can verify this scenario are pointed out. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0002/0002037v3.pdf"}
{"id": "quant-ph0101015", "abstract": "  It is possible to extract work from a quantum-mechanical system whose dynamics is governed by a time-dependent cyclic Hamiltonian. An energy bath is required to operate such a quantum engine in place of the heat bath used to run a conventional classical thermodynamic heat engine. The effect of the energy bath is to maintain the expectation value of the system Hamiltonian during an isoenergetic expansion. It is shown that the existence of such a bath leads to equilibrium quantum states that maximise the von Neumann entropy. Quantum analogues of certain thermodynamic relations are obtained that allow one to define the temperature of the energy bath. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0101/0101015v2.pdf"}
{"id": "quant-ph0101136", "abstract": "  We show that it is impossible to determine the time a tunneling particle spends under the barrier. However, it is possible to determine the asymptotic time, i.e., the time the particle spends in a large area including the barrier. We propose a model of time measurements. The model provides a procedure for calculation of the asymptotic tunneling and reflection times. The model also demonstrates the impossibility of determination of the time the tunneling particle spends under the barrier. Examples for delta-form and rectangular barrier illustrate the obtained results. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0101/0101136v1.pdf"}
{"id": "quant-ph0105032", "abstract": "  We present a quantum digital signature scheme whose security is based on fundamental principles of quantum physics. It allows a sender (Alice) to sign a message in such a way that the signature can be validated by a number of different people, and all will agree either that the message came from Alice or that it has been tampered with. To accomplish this task, each recipient of the message must have a copy of Alice's \"public key,\" which is a set of quantum states whose exact identity is known only to Alice. Quantum public keys are more difficult to deal with than classical public keys: for instance, only a limited number of copies can be in circulation, or the scheme becomes insecure. However, in exchange for this price, we achieve unconditionally secure digital signatures. Sending an m-bit message uses up O(m) quantum bits for each recipient of the public key. We briefly discuss how to securely distribute quantum public keys, and show the signature scheme is absolutely secure using one method of key distribution. The protocol provides a model for importing the ideas of classical public key cryptography into the quantum world. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0105/0105032v2.pdf"}
{"id": "quant-ph0105076", "abstract": "  We present a simple method to deal with caustics in the semiclassical approximation to the thermal density matrix of a particle moving on the line. For simplicity, only its diagonal elements are considered. The only ingredient we require is the knowledge of the extrema of the Euclidean action. The procedure makes use of complex trajectories, and is applied to the quartic double-well potential. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0105/0105076v2.pdf"}
{"id": "quant-ph0110134", "abstract": "  We consider a general central-field system in D dimensions and show that the division of the kinetic energy into radial and angular parts proceeds differently in the wavefunction picture and the Weyl-Wigner phase-space picture. Thus, the radial and angular kinetic energies are different quantities in the two pictures, containing different physical information, but the relation between them is well defined. We discuss this relation and illustrate its nature by examples referring to a free particle and to a ground-state hydrogen atom. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0110/0110134v1.pdf"}
{"id": "quant-ph0201120", "abstract": "  A quantum computer directly manipulates information stored in the state of quantum mechanical systems. The available operations have many attractive features but also underly severe restrictions, which complicate the design of quantum algorithms. We present a divide-and-conquer approach to the design of various quantum algorithms. The class of algorithm includes many transforms which are well-known in classical signal processing applications. We show how fast quantum algorithms can be derived for the discrete Fourier transform, the Walsh-Hadamard transform, the Slant transform, and the Hartley transform. All these algorithms use at most O(log^2 N) operations to transform a state vector of a quantum computer of length N. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0201/0201120v1.pdf"}
{"id": "quant-ph0305112", "abstract": "  We show that the two slit experiment in which a single quantum particle interferes with itself can be interpreted as a quantum fingerprinting protocol: the interference pattern exhibited by the particle contains information about the environment it encountered in the slits which would require much more communication to learn classically than is required quantum mechanically. An extension to the case where the particle has many internal degrees of freedom is suggested and its interpretation is discussed in detail. A possible experimental realization is proposed. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0305/0305112v1.pdf"}
{"id": "quant-ph0309064", "abstract": "  It is shown that the canonical problem of classical statistical thermodynamics, the computation of the partition function, is in the case of +/-J Ising spin glasses a particular instance of certain simple sums known as quadratically signed weight enumerators (QWGTs). On the other hand it is known that quantum computing is polynomially equivalent to classical probabilistic computing with an oracle for estimating QWGTs. This suggests a connection between the partition function estimation problem for spin glasses and quantum computation. This connection extends to knots and graph theory via the equivalence of the Kauffman polynomial and the partition function for the Potts model. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0309/0309064v2.pdf"}
{"id": "quant-ph0404035", "abstract": "  We discuss radiation fields in a compact space of finite size instead of that in a cavity for investigating the coupled atom-radiation field system. Representations of T(1)× SO(4) group are used to give a formulation for kinematics of the radiation fields. The explicit geometrical parameter dependence of statistical properties of radiation fields is obtained. Results show remarkable differences from that of the black-body radiation system in free space. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0404/0404035v1.pdf"}
{"id": "quant-ph0407256", "abstract": "  We present a scheme for secure deterministic quantum communication without using entanglement, in a Plug-and-Play fashion. The protocol is completely deterministic, both in the encoding procedure and in the control one, thus doubling the communication rate with respect to other setups; moreover, deterministic nature of transmission, apart from rendering unnecessary bases revelation on the public channel, allows the realization of protocols like `direct communication' and `quantum dialogue'. The encoding exploits the phase degree of freedom of a photon, thus paving the way to an optical fiber implementation, feasible with present day technology. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0407/0407256v2.pdf"}
{"id": "quant-ph0503013", "abstract": "  We show that the analysis of entanglement distillation protocols for qudits of arbitrary dimension D benefits from applying basic concepts from number theory, since the set  associated to Bell diagonal states is a module rather than a vector space. We find that a partition of  into divisor classes characterizes the invariant properties of mixed Bell diagonal states under local permutations. We construct a very general class of recursion protocols by means of unitary operations implementing these local permutations. We study these distillation protocols depending on whether we use twirling operations in the intermediate steps or not, and we study them both analitically and numerically with Monte Carlo methods. In the absence of twirling operations, we construct extensions of the quantum privacy algorithms valid for secure communications with qudits of any dimension D. When D is a prime number, we show that distillation protocols are optimal both qualitatively and quantitatively. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0503/0503013v1.pdf"}
{"id": "quant-ph0503217", "abstract": "  We study the number of coincidences in a Hong-Ou-Mandel interferometer exit whose arms have been supplemented with the addition of one or two optical cavities. The fourth-order correlation function at the beam-splitter exit is calculated. In the regime where the cavity length are larger than the one-photon coherence length, photon coalescence and anti-coalescence interference is observed. Feynman's path diagrams for the indistinguishable processes that lead to quantum interference are presented. As application for the Hong-Ou-Mandel interferometer with two cavities, it is discussed the construction of an optical XOR gate. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0503/0503217v1.pdf"}
{"id": "quant-ph0505014", "abstract": "  We demonstrate an atom localization scheme based on monitoring of the atomic coherences. We consider atomic transitions in a Lambda configuration where the control field is a standing wave field. The probe field and the control field produce coherence between the two ground states. We show that this coherence has the same fringe pattern as produced by a Fabry-Perot interferometer and thus measurement of the atomic coherence would localize the atom. Interestingly enough the role of the cavity finesse is played by the ratio of the intensities of the pump and probe. This is in fact the reason for obtaining extreme subwavelenth localization. We suggest several methods to monitor the produced localization. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0505/0505014v2.pdf"}
{"id": "quant-ph0509039", "abstract": "  We consider the problem of controlling the motion of an atom trapped in an optical cavity using continuous feedback. In order to realize such a scheme experimentally, one must be able to perform state estimation of the atomic motion in real time. While in theory this estimate may be provided by a stochastic master equation describing the full dynamics of the observed system, integrating this equation in real time is impractical. Here we derive an approximate estimation equation for this purpose, and use it as a drive in a feedback algorithm designed to cool the motion of the atom. We examine the effectiveness of such a procedure using full simulations of the cavity QED system, including the quantized motion of the atom in one dimension. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0509/0509039v2.pdf"}
{"id": "quant-ph0510160", "abstract": "  We propose a “channelization” architecture to achieve wide-band electromagnetically induced transparency (EIT) and ultra-slow light propagation in atomic Rb-87 vapors. EIT and slow light are achieved by shining a strong, resonant “pump” laser on the atomic medium, which allows slow and unattenuated propagation of a weaker “signal” beam, but only when a two-photon resonance condition is satisfied. Our wideband architecture is accomplished by dispersing a wideband signal spatially, transverse to the propagation direction, prior to entering the atomic cell. When particular Zeeman sub-levels are used in the EIT system, then one can introduce a magnetic field with a linear gradient such that the two-photon resonance condition is satisfied for each individual frequency component. Because slow light is a group velocity effect, utilizing differential phase shifts across the spectrum of a light pulse, one must then introduce a slight mismatch from perfect resonance to induce a delay. We present a model which accounts for diffusion of the atoms in the varying magnetic field as well as interaction with levels outside the ideal three-level system on which EIT is based. We find the maximum delay-bandwidth product decreases with bandwidth, and that delay-bandwidth product  1 should be achievable with bandwidth  50 MHz ( 5 ns delay). This is a large improvement over the  1 MHz bandwidths in conventional slow light systems and could be of use in signal processing applications. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0510/0510160v1.pdf"}
{"id": "quant-ph0511106", "abstract": "  Stability and instability of quantum evolution are studied in the interaction between a two-level atom with photon recoil and a quantized field mode in an ideal cavity, the basic model of cavity quantum electrodynamics (QED). It is shown that the Jaynes-Cummings dynamics can be unstable in the regime of chaotic walking of the atomic center-of-mass in the quantized field of a standing wave in the absence of any kind of interaction with environment. This kind of quantum instability manifests itself in strong variations of reduced quantum purity and entropy, correlating with the respective classical Lyapunov exponent, and in exponential sensitivity of fidelity of quantum states to small variations in the atom-field detuning. The connection between quantum entanglement and fidelity and the center-of-mass motion is clarified analytically and numerically for a few regimes of that motion. The results are illustrated with two specific initial field states: the Fock and coherent ones. Numerical experiments demonstrate various manifestations of the quantum-classical correspondence, including dynamical chaos and fractals, which can be, in principle, observed in real experiments with atoms and photons in high finesse cavities. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0511/0511106v1.pdf"}
{"id": "quant-ph0512086", "abstract": "  The stable periodic orbits of an area-preserving map on the 2-torus, which is formally a variant of the Standard Map, have been shown to explain the quantum accelerator modes that were discovered in experiments with laser-cooled atoms. We show that their parametric dependence exhibits Arnol'd-like tongues and perform a perturbative analysis of such structures. We thus explain the arithmetical organisation of the accelerator modes and discuss experimental implications thereof. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0512/0512086v1.pdf"}
{"id": "quant-ph0601124", "abstract": "  We propose a quantum dot architecture for enabling universal quantum information processing. Quantum registers, consisting of arrays of vertically stacked self-assembled semiconductor quantum dots, are connected by chains of in-plane self-assembled dots. We propose an entanglement distributor, a device for producing and distributing maximally entangled qubits on demand, communicated through in-plane dot chains. This enables the transmission of entanglement to spatially separated register stacks, providing a resource for the realisation of a sizeable quantum processor built from coupled register stacks of practical size. Our entanglement distributor could be integrated into many of the present proposals for self-assembled quantum dot-based quantum computation. Our device exploits the properties of simple, relatively short, spin-chains and does not require microcavities. Utilizing the properties of self-assembled quantum dots, after distribution the entanglement can be mapped into relatively long lived spin qubits and purified, providing a flexible, distributed, off-line resource. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0601/0601124v2.pdf"}
{"id": "quant-ph0604051", "abstract": "  We experimentally investigate a double-pass parametric down-conversion scheme for producing pulsed, polarization-entangled photon pairs with high visibility. The amplitudes for creating photon pairs on each pass interfere to compensate for distinguishing characteristics that normally degrade two-photon visibility. The result is a high-flux source of polarization-entangled photon pulses that does not require spectral filtering. We observe quantum interference visibility of over 95", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0604/0604051v1.pdf"}
{"id": "quant-ph0606098", "abstract": "  We present a scheme for implementing the unconventional geometric two-qubit phase gate with nonzero dynamical phase by using the two-channel Raman interaction of two atoms in a cavity. We show that the dynamical phase acquired in a cyclic evolution is proportional to the geometric phase acquired in the same cyclic evolution, hence the the total phase possesses the same geometric features as the geometric phase. In our scheme the atomic excited state is adiabatically eliminated and the operation of the proposed logic gate involves only in the metastable states of the atom and hence is not affected by spontaneous emission. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0606/0606098v1.pdf"}
{"id": "quant-ph0606124", "abstract": "  We investigate the ratchet current that appears in a kicked Hamiltonian system when the period of the kicks corresponds to the regime of quantum resonance. In the classical analogue, a spatial-temporal symmetry should be broken to obtain a net directed current. It was recently discovered that in quantum resonance the temporal symmetry can be kept, and we prove that breaking the spatial symmetry is a necessary condition to find this effect.   Moreover, we show numerically and analytically how the direction of the motion is dramatically influenced by the strength of the kicking potential and the value of the period. By increasing the strength of the interaction this direction changes periodically, providing us with a non-expected source of current reversals in this quantum model. These reversals depend on the kicking period also, though this behavior is theoretically more difficult to analyze. Finally, we generalize the discussion to the case of a non-uniform initial condition. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0606/0606124v2.pdf"}
{"id": "quant-ph0612213", "abstract": "  We describe the behavior of two coupled Bose-Einstein condensates in time-dependent (TD) trap potentials and TD Rabi (or tunneling) frequency, using the two-mode approach. Starting from Bloch states, we succeed to get analytical solutions for the TD Schroedinger equation and present a detailed analysis of the relative and geometric phases acquired by the wave function of the condensates, as well as their population imbalance. We also establish a connection between the geometric phases and constants of motion which characterize the dynamic of the system. Besides analyzing the affects of temporality on condensates that differs by hyperfine degrees of freedom   (internal Josephson effect), we also do present a brief discussion of a one specie condensate in a double-well potential   (external Josephson effect). ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0612/0612213v1.pdf"}
{"id": "quant-ph0701150", "abstract": "  We analyze the realization of a quantum-walk search algorithm in a passive, linear optical network. The specific model enables us to consider the effect of realistic sources of noise and losses on the search efficiency. Photon loss uniform in all directions is shown to lead to the rescaling of search time. Deviation from directional uniformity leads to the enhancement of the search efficiency compared to uniform loss with the same average. In certain cases even increasing loss in some of the directions can improve search efficiency. We show that while we approach the classical limit of the general search algorithm by introducing random phase fluctuations, its utility for searching is lost. Using numerical methods, we found that for static phase errors the averaged search efficiency displays a damped oscillatory behaviour that asymptotically tends to a non-zero value. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0701/0701150v3.pdf"}
{"id": "quant-ph0703207", "abstract": "  We demonstrate that spin chains are experimentally feasible using electrons confined in micro-Penning traps, supplemented with local magnetic field gradients. The resulting Heisenberg-like system is characterized by coupling strengths showing a dipolar decay. These spin chains can be used as a channel for short distance quantum communication. Our scheme offers high accuracy in reproducing an effective spin chain with relatively large transmission rate. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0703/0703207v1.pdf"}
{"id": "quant-ph9608004", "abstract": "  Quantum trajectory methods can be used for a wide range of open quantum systems to solve the master equation by unraveling the density operator evolution into individual stochastic trajectories in Hilbert space. This C++ class library offers a choice of integration algorithms for three important unravelings of the master equation. Different physical systems are modeled by different Hamiltonians and environment operators. The program achieves flexibility and user friendliness, without sacrificing execution speed, through the way it represents operators and states in Hilbert space. Primary operators, implemented in the form of simple routines acting on single degrees of freedom, can be used to build up arbitrarily complex operators in product Hilbert spaces with arbitrary numbers of components. Standard algebraic notation is used to build operators and to perform arithmetic operations on operators and states. States can be represented in a local moving basis, often leading to dramatic savings of computing resources. The state and operator classes are very general and can be used independently of the quantum trajectory algorithms. Only a rudimentary knowledge of C++ is required to use this package. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/9608/9608004v1.pdf"}
{"id": "quant-ph9708019", "abstract": "  We consider the communication complexity of the binary inner product function in a variation of the two-party scenario where the parties have an a priori supply of particles in an entangled quantum state. We prove linear lower bounds for both exact protocols, as well as for protocols that determine the answer with bounded-error probability. Our proofs employ a novel kind of \"quantum\" reduction from a quantum information theory problem to the problem of computing the inner product. The communication required for the former problem can then be bounded by an application of Holevo's theorem. We also give a specific example of a probabilistic scenario where entanglement reduces the communication complexity of the inner product function by one bit. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/9708/9708019v3.pdf"}
{"id": "quant-ph9803057", "abstract": "  The dynamics of a decohering two-level system driven by a suitable control Hamiltonian is studied. The control procedure is implemented as a sequence of radiofrequency pulses that repetitively flip the state of the system, a technique that can be termed quantum \"bang-bang\" control after its classical analog. Decoherence introduced by the system's interaction with a quantum environment is shown to be washed out completely in the limit of continuous flipping and greatly suppressed provided the interval between the pulses is made comparable to the correlation time of the environment. The model suggests a strategy to fight against decoherence that complements existing quantum error-correction techniques. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/9803/9803057v1.pdf"}
{"id": "quant-ph9804056", "abstract": "  The imposition of boundary conditions upon a quantized field can lead to singular energy densities on the boundary. We treat the boundaries as quantum mechanical objects with a nonzero position uncertainty, and show that the singular energy density is removed. This treatment also resolves a long standing paradox concerning the total energy of the minimally coupled and conformally coupled scalar fields. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/9804/9804056v2.pdf"}
{"id": "0704.0476", "abstract": "  We investigate the geometric phase of an atom inside an adiabatic radio frequency (rf) potential created from a static magnetic field (B-field) and a time dependent rf field. The spatial motion of the atomic center of mass is shown to give rise to a geometric phase, or Berry's phase, to the adiabatically evolving atomic hyperfine spin along the local B-field. This phase is found to depend on both the static B-field along the semi-classical trajectory of the atomic center of mass and an “effective magnetic field” of the total B-field, including the oscillating rf field. Specific calculations are provided for several recent atom interferometry experiments and proposals utilizing adiabatic rf potentials. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.0476v1.pdf"}
{"id": "0704.0863", "abstract": "  The discovery of a flux excess in the far-ultraviolet (UV) spectrum of elliptical galaxies was a major surprise in 1969. While it is now clear that this UV excess is caused by an old population of hot helium-burning stars without large hydrogen-rich envelopes, rather than young stars, their origin has remained a mystery. Here we show that these stars most likely lost their envelopes because of binary interactions, similar to the hot subdwarf population in our own Galaxy. We have developed an evolutionary population synthesis model for the far-UV excess of elliptical galaxies based on the binary model developed by Han et al (2002, 2003) for the formation of hot subdwarfs in our Galaxy. Despite its simplicity, it successfully reproduces most of the properties of elliptical galaxies with a UV excess: the range of observed UV excesses, both in (1550-V) and (2000-V), and their evolution with redshift. We also present colour-colour diagrams for use as diagnostic tools in the study of elliptical galaxies. The model has major implications for understanding the evolution of the UV excess and of elliptical galaxies in general. In particular, it implies that the UV excess is not a sign of age, as had been postulated previously, and predicts that it should not be strongly dependent on the metallicity of the population, but exists universally from dwarf ellipticals to giant ellipticals. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.0863v3.pdf"}
{"id": "0704.0892", "abstract": "  Pattern formation and evolution in unsynchronizable complex networks are investigated. Due to the asymmetric topology, the synchronous patterns formed in complex networks are irregular and nonstationary. For coupling strength immediately out of the synchronizable region, the typical phenomenon is the on-off intermittency of the system dynamics. The patterns appeared in this process are signatured by the coexistence of a giant cluster, which comprises most of the nodes, and a few number of small clusters. The pattern evolution is characterized by the giant cluster irregularly absorbs or emits the small clusters. As the coupling strength leaves away from the synchronization bifurcation point, the giant cluster is gradually dissolved into a number of small clusters, and the system dynamics is characterized by the integration and separation of the small clusters. Dynamical mechanisms and statistical properties of the nonstationary pattern evolution are analyzed and conducted, and some scalings are newly revealed. Remarkably, it is found that the few active nodes, which escape from the giant cluster with a high frequency, are independent of the coupling strength while are sensitive to the bifurcation types. We hope our findings about nonstationary pattern could give additional understandings to the dynamics of complex systems and have implications to some real problems where systems maintain their normal functions only in the unsynchronizable state. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.0892v1.pdf"}
{"id": "0704.1520", "abstract": "  We study the kinetic theory of driven granular gases, taking into account both translational and rotational degrees of freedom. We obtain the high-energy tail of the stationary bivariate energy distribution, depending on the total energy E and the ratio x=sqrtE_w/E of rotational energy E_w to total energy. Extremely energetic particles have a unique and well-defined distribution f(x) which has several remarkable features: x is not uniformly distributed as in molecular gases; f(x) is not smooth but has multiple singularities. The latter behavior is sensitive to material properties such as the collision parameters, the moment of inertia and the collision rate. Interestingly, there are preferred ratios of rotational-to-total energy. In general, f(x) is strongly correlated with energy and the deviations from a uniform distribution grow with energy. We also solve for the energy distribution of freely cooling Maxwell Molecules and find qualitatively similar behavior. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.1520v1.pdf"}
{"id": "0704.2174", "abstract": "  Since October 1, 2006, spectroscopic data from the two FORS instruments have been reduced with a new pipeline, which is based on a bottom-up calibration approach. I give a short description of the pipeline and discuss first experiences with automatic data reduction using this software, which has significantly increased the percentage of processed data for both instruments. I will also describe possible new options for Quality Control. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.2174v1.pdf"}
{"id": "0704.2567", "abstract": "  In a previous work (M. Campisi. Stud. Hist. Phil. M. P. 36 (2005) 275-290) we have addressed the mechanical foundations of equilibrium thermodynamics on the basis of the Generalized Helmholtz Theorem. It was found that the volume entropy provides a good mechanical analogue of thermodynamic entropy because it satisfies the heat theorem and it is an adiabatic invariant. This property explains the “equal” sign in Clausius principle (S_f ≥ S_i) in a purely mechanical way and suggests that the volume entropy might explain the “larger than” sign (i.e. the Law of Entropy Increase) if non adiabatic transformations were considered. Based on the principles of microscopic (quantum or classical) mechanics here we prove that, provided the initial equilibrium satisfy the natural condition of decreasing ordering of probabilities, the expectation value of the volume entropy cannot decrease for arbitrary transformations performed by some external sources of work on a insulated system. This can be regarded as a rigorous quantum mechanical proof of the Second Law. We discuss how this result relates to the Minimal Work Principle and improves over previous attempts. The natural evolution of entropy is towards larger values because the natural state of matter is at positive temperature. Actually the Law of Entropy Decrease holds in artificially prepared negative temperature systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.2567v1.pdf"}
{"id": "0704.3074", "abstract": "  General relativity allows solutions exhibiting closed timelike curves. Time travel generates paradoxes and quantum mechanics generalizations were proposed to solve those paradoxes. The implications of self-consistent interactions on acausal region of space-time are investigated. If the correspondence principle is true, then all generalizations of quantum mechanics on acausal manifolds are not renormalizable. Therefore quantum mechanics can only be defined on global hyperbolic manifolds and all general relativity solutions exhibiting time travel are unphysical. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.3074v1.pdf"}
{"id": "0704.3284", "abstract": "  We examine one- and two-dimensional (1D and 2D) models of linearly coupled lattices of the discrete-nonlinear-Schrödinger type. Analyzing ground states of the systems with equal powers in the two components, we find a symmetry-breaking phenomenon beyond a critical value of the squared l^2-norm. Asymmetric states, with unequal powers in their components, emerge through a subcritical pitchfork bifurcation, which, for very weakly coupled lattices, changes into a supercritical one. We identify the stability of various solution branches. Dynamical manifestations of the symmetry breaking are studied by simulating the evolution of the unstable branches. The results present the first example of spontaneous symmetry breaking in 2D lattice solitons. This feature has no counterpart in the continuum limit, because of the collapse instability in the latter case. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.3284v1.pdf"}
{"id": "0704.3394", "abstract": "  We model energy dependencies of the quasi periodic oscillations (QPO) in the model of disc epicyclic motions, with X-ray modulation caused by varying relativistic effects. The model was proposed to explain the high frequency QPO observed in X-ray binaries. We consider two specific scenarios for the geometry of accretion flow and spectral formation. Firstly, a standard cold accretion disc with an active X-ray emitting corona is assumed to oscillate. Secondly, only a hot X-ray emitting accretion flow oscillates, while the cold disc is absent at the QPO radius. We find that the QPO spectra are generally similar to the spectrum of radiation emitted at the QPO radius, and they are broadened by the relativistic effects. In particular, the QPO spectrum contains the disc component in the oscillating disc with a corona scenario. We also review the available data on energy dependencies of high frequency QPO, and we point out that they appear to lack the disc component in their energy spectra. This would suggest the hot flow geometry in the spectral states when high frequency QPO are observed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.3394v1.pdf"}
{"id": "0704.3479", "abstract": "  We obtain the initial phase space distribution after relativistic heavy ion collision by the CGC shattering method incorporating the uncertainty principle and solve the semi-classical Boltzmann equation which includes the gluon radiation processes. We present as a function of time the attenuation rate of high p_T partons, which have transverse momenta over 6 GeV/c, in the medium which is formed after relativistic heavy ion collision. We calculate the elliptic flow as a function of an impact parameter, time and transverse momentum and also present the polar anisotropy, which gives the initial condition for color filamentation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.3479v1.pdf"}
{"id": "0704.3932", "abstract": "  We present a rigorous calculation of the dynamical friction force exerted on a spherical massive perturber moving through an infinite homogenous system of field stars. By calculating the shape and mass of the polarization cloud induced by the perturber in the background system, which decelerates the motion of the perturber, we recover Chandrasekhar's drag force law with a modified Coulomb logarithm. As concrete examples we calculate the drag force exerted on a Plummer sphere or a sphere with the density distribution of a Hernquist profile. It is shown that the shape of the perturber affects only the exact form of the Coulomb logarithm. The latter converges on small scales, because encounters of the test and field stars with impact parameters less than the size of the massive perturber become inefficient. We confirm this way earlier results based on the impulse approximation of small angle scatterings. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0704/0704.3932v1.pdf"}
{"id": "0705.1091", "abstract": "  We study the effects of different forms of information feedback associated with mass media on an agent-agent based model of the dynamics of cultural dissemination. In addition to some processes previously considered, we also examine a model of local mass media influence in cultural dynamics. Two mechanisms of information feedback are investigated: (i) direct mass media influence, where local or global mass media act as an additional element in the network of interactions of each agent, and (ii) indirect mass media influence, where global media acts as a filter of the influence of the existing network of interactions of each agent. Our results generalize previous findings showing that cultural diversity builds-up by increasing the strength of the mass media influence. We find that this occurs independently of the mechanisms of action (direct or indirect) of the mass media message. However, through an analysis of the full range of parameters measuring cultural diversity, we establish that the enhancement of cultural diversity produced by interaction with mass media only occurs for strong enough mass media messages. In comparison with previous studies a main different result is that weak mass media messages, in combination with agent-agent interaction, are efficient in producing cultural homogeneity. Moreover, the homogenizing effect of weak mass media messages are more efficient for direct local mass media messages than for global mass media messages or indirect global mass media influences. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.1091v1.pdf"}
{"id": "0705.1733", "abstract": "  Energy injection into the early universe can induce turbulent motions of the primordial plasma, which in turn act as a source for gravitational radiation. Earlier work computed the amplitude and characteristic frequency of the relic gravitational wave background, as a function of the total energy injected and the stirring scale of the turbulence. This paper computes the frequency spectrum of relic gravitational radiation from a turbulent source of the stationary Kolmogoroff form which acts for a given duration, making no other approximations. We also show that the limit of long source wavelengths, commonly employed in aeroacoustic problems, is an excellent approximation. The gravitational waves from cosmological turbulence around the electroweak energy scale will be detectable by future space-based laser interferometers for a substantial range of turbulence parameters. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.1733v3.pdf"}
{"id": "0705.1985", "abstract": "  We study the motion of two non-interacting quantum particles performing a random walk on a line and analyze the probability that the two particles are detected at a particular position after a certain number of steps (meeting problem). The results are compared to the corresponding classical problem and differences are pointed out. Analytic formulas for the meeting probability and its asymptotic behavior are derived. The decay of the meeting probability for distinguishable particles is faster then in the classical case, but not quadratically faster. Entangled initial states and the bosonic or fermionic nature of the walkers are considered. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.1985v1.pdf"}
{"id": "0705.3442", "abstract": "  The transverse motion inside a Stark decelerator plays a large role in the total efficiency of deceleration. We differentiate between two separate regimes of molecule loss during the slowing process. The first mechanism involves distributed loss due to coupling of transverse and longitudinal motion, while the second is a result of the rapid decrease of the molecular velocity within the final few stages. In this work, we describe these effects and present means for overcoming them. Solutions based on modified switching time sequences with the existing decelerator geometry lead to a large gain of stable molecules in the intermediate velocity regime, but fail to address the loss at very low final velocities. We propose a new decelerator design, the quadrupole-guiding decelerator, which eliminates distributed loss due to transverse/longitudinal couplings throughout the slowing process and also exhibits gain over normal deceleration to the lowest velocities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.3442v1.pdf"}
{"id": "0706.4242", "abstract": "  The properties and behaviour of the solutions of the recently obtained k_t-dependent evolution equations are investigated. When used to reproduce transverse momentum spectra of hadrons in Semi-Inclusive DIS, an encouraging agreement with data is found. The present analysis also supports at the phenomenological level the factorization properties of the Semi-Inclusive DIS cross-sections in terms of k_t-dependent distributions. Further improvements and possible developments of the proposed evolution equations are envisaged. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0706/0706.4242v2.pdf"}
{"id": "0706.4248", "abstract": "  We numerically model the evolution of dust in a protoplanetary disk using a two-phase (gas+dust) Smoothed Particle Hydrodynamics (SPH) code, which is non-self-gravitating and locally isothermal. The code follows the three dimensional distribution of dust in a protoplanetary disk as it interacts with the gas via aerodynamic drag. In this work, we present the evolution of a disk comprising 1", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0706/0706.4248v1.pdf"}
{"id": "0707.1992", "abstract": "  We study a stochastic predator-prey model on a square lattice, where each of the six species has two superior and two inferior partners. The invasion probabilities between species depend on the predator-prey pair and are supplemented by Gaussian noise. Conditions are identified that warrant the largest impact of noise on the evolutionary process, and the results of Monte Carlo simulations are qualitatively reproduced by a four-point cluster dynamical mean-field approximation. The observed noise-guided evolution is deeply routed in short-range spatial correlations, which is supported by simulations on other host lattice topologies. Our findings are conceptually related to the coherence resonance phenomenon in dynamical systems via the mechanism of threshold duality. We also show that the introduced concept of noise-guided evolution via the exploitation of threshold duality is not limited to predator-prey cyclical interactions, but may apply to models of evolutionary game theory as well, thus indicating its applicability in several different fields of research. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0707/0707.1992v1.pdf"}
{"id": "0707.2909", "abstract": "  The dynamics of populations is rich, taking into account that both, the individual's actions and the population's fitness are coupled. The way in which an individual chooses a strategy depends off course on the interaction with other individuals and the relation between selection and mutation within the population. The present model considers individuals with memory. This memory is represented by a device where information of past actions is stored as bits in a 1D Ising chain. The selection of a new individual action depends on the individual's memory. If the selection of a strategy does not improve the individual's fitness, a new individual with different memory size replaces it. Both, actions and memory are observables that characterize the population. They can change in time, and both depend on the fitness of the population. This model allows the implementation of learning parameters as well as an external information source, acting as an external field which drives individuals to select one preferred action. In particular we show that the diversity of the population, measured as a Shannon's diversity index (equivalent to a neg-entropy), is not only related to the energy consumption and size of the system, but is also related to the way in which the individuals are influenced by the external field. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0707/0707.2909v1.pdf"}
{"id": "0707.3236", "abstract": "  This article demonstrates how to develop a Microchip PIC16F84 based device that supports RS-232 interface with PC. Circuit (LED Board) design and software development will be discussed. PicBasic Pro Compiler from microEngineering Labs, Inc. is used for PIC programming. Development of LED Board Control Console using C/C++ is also briefly discussed. The project requires basic work experience with Microchip PICs, serial communication and programming. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0707/0707.3236v1.pdf"}
{"id": "0708.0449", "abstract": "  We consider a toy model of the interaction of a qubit with an exotic space-time containing a time-like curve. Consistency seems to require that the global evolution of the qubit be non-unitary. Given that quantum mechanics is globally unitary, this then is an example of a quantum gravity information paradox. However, we show that a careful analysis of the problem in the Heisenberg picture reveals an underlying unitarity, thus resolving the paradox. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0708/0708.0449v1.pdf"}
{"id": "0708.0992", "abstract": "  We investigate the effect of the bulk contents in the DGP braneworld on the evolution of the universe. We find that although the pure DGP model cannot accommodate the transition of the effective equation of state of dark energy, once the bulk matter T^5_5 is considered, the modified model can realize the w_eff crossing -1. However this transition of the equation of state cannot be realized by just considering bulk-brane energy exchange or the GB effect while the bulk matter contribution is not included. T^5_5 plays the major role in the modified DGP model to have the w crossing -1 behavior. We show that our model can describe the super-acceleration of our universe with the equation of state of the effective dark energy and the Hubble parameter in agreement with observations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0708/0708.0992v2.pdf"}
{"id": "0708.2183", "abstract": "  The isothermal compression of a dilute nucleonic gas invoking cluster degrees of freedom is studied in an equilibrium statistical model; this clusterized system is found to be more stable than the pure nucleonic system. The equation of state (EoS) of this matter shows features qualitatively very similar to the one obtained from pure nucleonic gas. In the isothermal compression process, there is a sudden enhancement of clusterization at a transition density rendering features analogous to the gas-liquid phase transition in normal dilute nucleonic matter. Different observables like the caloric curves, heat capacity, isospin distillation, etc. are studied in both the models. Possible changes in the observables due to recently indicated medium modifications in the symmetry energy are also investigated. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0708/0708.2183v2.pdf"}
{"id": "0708.2479", "abstract": "  We study the atomic oxygen adsorption on Pb(111) surface by using density-functional theory within the generalized gradient approximation and a supercell approach. The atomic and energetic properties of purely on-surface and subsurface oxygen structures at the Pb(111) surface are systematically investigated for a wide range of coverages and adsorption sites. The fcc and tetra-II sites (see the text for definition) are found to be energetically preferred for the on-surface and subsurface adsorption, respectively, in the whole range of coverage considered. The on-surface and subsurface oxygen binding energies monotonically increase with the coverage, and the latter is always higher than the former, thus indicating the tendency to the formation of oxygen islands (clusters) and the higher stability of subsurface adsorption. The on-surface and subsurface diffusion-path energetics of atomic oxygen, and the activation barriers for the O penetration from the on-surface to the subsurface sites are presented at low and high coverages. In particular, it is shown that the penetration barrier from the on-surface hcp to the subsurface tetra-I site is as small as 65 meV at low coverage (Θ=0.25). The other properties of the O/Pb(111) system, including the charge distribution, the lattice relaxation, the work function, and the electronic density of states, are also studied and discussed in detail, which consistently show the gradually stabilizing ionic O-Pb bond with increase of the oxygen coverage. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0708/0708.2479v1.pdf"}
{"id": "0709.0171", "abstract": "  We study the heavy-heavy-light quark (QQq) system in a non-relativistic potential model, and investigate the quark motional effect on the inter-two-quark potential in baryons. We adopt the Hamiltonian with the static three-quark potential which is obtained by the first-principle calculation of lattice QCD, rather than the two-body force in ordinary quark models. Using the renormalization-group inspired variational method in discretized space, we calculate the ground-state energy of QQq systems and the light-quark spatial distribution. We find that the effective string tension between the two heavy quarks is reduced compared to the static three-quark case. This reduction of the effective string tension originates from the geometrical difference between the inter-quark distance and the flux-tube length, and is conjectured to be a general property for baryons. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0709/0709.0171v2.pdf"}
{"id": "0709.1540", "abstract": "  We present a dynamic density functional theory (dDFT) which takes into accou nt the advection of the particles by a flowing solvent. For potential flows we can use the same closure as in the absence of solvent flow. The structure of the resulting advected dDFT suggests that it could be used for non-potential flows as well. We apply this dDFT to Brownian particles (e.g., polymer coils) in a solvent flowing around a spherical obstacle (e.g., a colloid) and compare the results with direct simulations of the underlying Brownian dynamics.   Although numerical limitations do not allow for an accurate quantitative check of the advected dDFT both show the same qualitative features. In contrast to previous works which neglected the deformation of the flow by the obstacle, we find that the bow-wave in the density distribution of particles in front of the obstacle as well as the wake behind it are reduced dramatically. As a consequence the friction force exerted by the (polymer) particles on the colloid can be reduced drastically. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0709/0709.1540v1.pdf"}
{"id": "0709.2837", "abstract": "  This contribution investigates a prototype of a TPC readout with a highly pixelated CMOS ASIC, which is an option for charged particles tracking of the ILC. A triple GEM stack was joined with a TimePix and MediPix2 chip (pixel size of 55×55 μ m^2) and its readout properties were investigated with 5 GeV electrons. The spatial resolution of the cluster center reconstruction was determined as a function of drift distance using different cluster alhoritms and compared with Monte Carlo predictions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0709/0709.2837v1.pdf"}
{"id": "0709.3904", "abstract": "  The shear flow and the dielectric alpha-process in molecular glass formers is modeled in terms of local structural rearrangements which reverse a strong local shear. Using Eshelby's solution of the corresponding elasticity theory problem (J. D. Eshelby, Proc. Roy. Soc. A241, 376 (1957)), one can calculate the recoverable compliance and estimate the lifetime of the symmetric double-well potential characterizing such a structural rearrangement. A full modeling of the shear relaxation spectra requires an additional parametrization of the barrier density of these structural rearrangements. The dielectric relaxation spectrum can be described as a folding of these relaxations with the Debye process. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0709/0709.3904v1.pdf"}
{"id": "0710.0916", "abstract": "  In this work, using the scattering matrix method, we have investigated the transmission coefficients and the thermal conductivity in a double-bend waveguide structure. The transmission coefficients show strong resonances due to the scattering in the midsection of a double-bend structure; the positions and the widths of the resonance peaks are determined by the dimensions of the midsection of the structure. And the scattering in the double-bend structure makes the thermal conductivity decreases with the increasing of the temperature first, then increases after reaches a minimum. Furthermore, the investigations of the multiple double-bend structures indicate that the first additional double-bend structure suppresses the transmission coefficient and the frequency gap formed; and the additional double-bend structures determine the numbers of the resonance peaks at the frequency just above the gap region. These results could be useful for the design of phonon devices. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.0916v1.pdf"}
{"id": "0710.1383", "abstract": "  A clear understanding the behavior of the error probability (EP) as a function of signal-to-noise ratio (SNR) and other system parameters is fundamental for assessing the design of digital wireless communication systems.We propose an analytical framework based on the log-concavity property of the EP which we prove for a wide family of multidimensional modulation formats in the presence of Gaussian disturbances and fading. Based on this property, we construct a class of local bounds for the EP that improve known generic bounds in a given region of the SNR and are invertible, as well as easily tractable for further analysis. This concept is motivated by the fact that communication systems often operate with performance in a certain region of interest (ROI) and, thus, it may be advantageous to have tighter bounds within this region instead of generic bounds valid for all SNRs. We present a possible application of these local bounds, but their relevance is beyond the example made in this paper. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.1383v2.pdf"}
{"id": "0710.1496", "abstract": "  A two-temperature Ising-Schelling model is introduced and studied for describing human segregation. The self-organized Ising model with Glauber kinetics simulated by Müller et al. exhibits a phase transition between segregated and mixed phases mimicking the change of tolerance (local temperature) of individuals. The effect of external noise is considered here as a second temperature added to the decision of individuals who consider change of accommodation. A numerical evidence is presented for a discontinuous phase transition of the magnetization. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.1496v1.pdf"}
{"id": "0710.1659", "abstract": "  We derive an exact and explicit Kraus decomposition for the reduced density of a quantum system simultaneously interacting with time-dependent external fields and a chaotic environment of thermodynamic dimension. We test the accuracy of the Kraus decomposition against exact numerical results for a CNOT gate performed on two qubits of an (N+2)-qubit statically flawed isolated quantum computer. Here the N idle qubits comprise the finite environment. We obtain very good agreement even for small N. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.1659v1.pdf"}
{"id": "0710.1777", "abstract": "  Studies of stellar magnetism at the pre-main sequence phase can provide important new insights into the detailed physics of the late stages of star formation, and into the observed properties of main sequence stars. This is especially true at intermediate stellar masses, where magnetic fields are strong and globally organised, and therefore most amenable to direct study. This talk reviews recent high-precision ESPaDOnS observations of pre-main sequence Herbig Ae-Be stars, which are yielding qualitatively new information about intermediate-mass stars: the origin and evolution of their magnetic fields, the role of magnetic fields in generating their spectroscopic activity and in mediating accretion in their late formative stages, and the factors influencing their rotational angular momentum. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.1777v1.pdf"}
{"id": "0710.1878", "abstract": "  We calculate the form factors and the coupling constant in the ρ D^* D^* vertex in the framework of QCD sum rules. We evaluate the three point correlation functions of the vertex considering both ρ and D^* mesons off–shell. The form factors obtained are very different but give the same coupling constant: g_ρ D^* D^* = 6.6 ± 0.31. This number is 50", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.1878v1.pdf"}
{"id": "0710.2263", "abstract": "  Surfaces serve as highly efficient catalysts for a vast variety of chemical reactions. Typically, such surface reactions involve billions of molecules which diffuse and react over macroscopic areas. Therefore, stochastic fluctuations are negligible and the reaction rates can be evaluated using rate equations, which are based on the mean-field approximation. However, in case that the surface is partitioned into a large number of disconnected microscopic domains, the number of reactants in each domain becomes small and it strongly fluctuates. This is, in fact, the situation in the interstellar medium, where some crucial reactions take place on the surfaces of microscopic dust grains. In this case rate equations fail and the simulation of surface reactions requires stochastic methods such as the master equation. However, in the case of complex reaction networks, the master equation becomes infeasible because the number of equations proliferates exponentially. To solve this problem, we introduce a stochastic method based on moment equations. In this method the number of equations is dramatically reduced to just one equation for each reactive species and one equation for each reaction. Moreover, the equations can be easily constructed using a diagrammatic approach. We demonstrate the method for a set of astrophysically relevant networks of increasing complexity. It is expected to be applicable in many other contexts in which problems that exhibit analogous structure appear, such as surface catalysis in nanoscale systems, aerosol chemistry in stratospheric clouds and genetic networks in cells. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.2263v1.pdf"}
{"id": "0710.2709", "abstract": "  We explore various aspects of dynamical black holes defined by a future outer trapping horizon in n(≥ 5)-dimensional Einstein-Gauss-Bonnet gravity. In the present paper, we assume that the spacetime has symmetries corresponding to the isometries of an (n-2)-dimensional maximally symmetric space and the Gauss-Bonnet coupling constant is non-negative. Depending on the existence or absence of the general relativistic limit, solutions are classified into GR and non-GR branches, respectively. Assuming the null energy condition on matter fields, we show that a future outer trapping horizon in the GR branch possesses the same properties as that in general relativity. In contrast, that in the non-GR branch is shown to be non-spacelike with its area non-increasing into the future. We can recognize this peculiar behavior to arise from a fact that the null energy condition necessarily leads to the null convergence condition for radial null vectors in the GR branch, but not in the non-GR branch. The energy balance law yields the first law of a trapping horizon, from which we can read off the entropy of a trapping horizon reproducing Iyer-Wald's expression. The entropy of a future outer trapping horizon is shown to be non-decreasing in both branches along its generator. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.2709v3.pdf"}
{"id": "0710.2864", "abstract": "  We present results from two high-contrast imaging surveys that exploit a novel technique, L-band angular differential imaging. Our first survey targeted 21 young stars in the Beta Pic and Tuc-Hor moving groups with VLT/NACO reaching typical sensitivities of <1 MJup at r > 20 AU. The statistical analysis of the null result demonstrates that the giant planet population is truncated at 30 AU or less (90", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.2864v1.pdf"}
{"id": "0710.3506", "abstract": "  We study the one-dimensional S=1/2 Heisenberg model with a uniform and a staggered magnetic fields, using the dynamical density-matrix renormalization group (DDMRG) technique. The DDMRG enables us to investigate the dynamical properties of chain with lengths up to a few hundreds, and the results are numerically exact in the same sense as 'exact diagonalization' results are. Thus, we can analyze the low-energy spectrum almost in the thermodynamic limit. In this work, we calculate the dynamical spin structure factor and demonstrate the performance of the DDMRG method applying the open-end boundary condition as well as the periodic boundary condition. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.3506v1.pdf"}
{"id": "0710.3698", "abstract": "  The physical processes that define the spine of the galaxy cluster X-ray luminosity – temperature (L-T) relation are investigated using a large hydrodynamical simulation of the Universe. This simulation models the same volume and phases as the Millennium Simulation and has a linear extent of 500 h^-1 Mpc. We demonstrate that mergers typically boost a cluster along but also slightly below the L-T relation. Due to this boost we expect that all of the very brightest clusters will be near the peak of a merger. Objects from near the top of the L-T relation tend to have assembled much of their mass earlier than an average halo of similar final mass. Conversely, objects from the bottom of the relation are often experiencing an ongoing or recent merger. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.3698v1.pdf"}
{"id": "0710.5303", "abstract": "  We have updated predictions for high energy neutrino and antineutrino charged current cross-sections within the conventional DGLAP formalism of NLO QCD using a modern PDF fit to HERA data, which also accounts in a systematic way for PDF uncertainties deriving from both model uncertainties and from the experimental uncertainties of the input data sets. Furthermore the PDFs are determined using an improved treatment of heavy quark thresholds. A measurement of the neutrino cross-section much below these predictions would signal the need for extension of the conventional formalism as in BFKL resummation, or even gluon recombination effects as in the colour glass condensate model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.5303v2.pdf"}
{"id": "0710.5418", "abstract": "  By applying recent results for the slab correlation time scale onto cosmic ray scattering theory, we compute cosmic ray parallel mean free paths within the quasilinear limit. By employing these results onto charged particle transport in the solar system, we demonstrate that much larger parallel mean free paths can be obtained in comparison to previous results. A comparison with solar wind observations is also presented to show that the new theoretical results are much closer to the observations than the previous results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.5418v1.pdf"}
{"id": "0710.5703", "abstract": "  The Sznajd model is investigated in the directed Erdos–Renyi network with the clusterization coefficient enhanced to 0.3 by the method of Holme and Kim (Phys. Rev. E65 (2002) 026107). Within additional triangles, all six links are present. In this network, some nodes preserve the minority opinion. The time tau of getting equilibrium is found to follow the log-normal distribution and it increases linearly with the system size. Its dependence on the initial opinion distribution is different from the analytical results for fully connected networks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0710/0710.5703v1.pdf"}
{"id": "0711.0689", "abstract": "  We present an efficient approach to continuous-time quantum error correction that extends the low-dimensional quantum filtering methodology developed by van Handel and Mabuchi [quant-ph/0511221 (2005)] to include error recovery operations in the form of real-time quantum feedback. We expect this paradigm to be useful for systems in which error recovery operations cannot be applied instantaneously. While we could not find an exact low-dimensional filter that combined both continuous syndrome measurement and a feedback Hamiltonian appropriate for error recovery, we developed an approximate reduced-dimensional model to do so. Simulations of the five-qubit code subjected to the symmetric depolarizing channel suggests that error correction based on our approximate filter performs essentially identically to correction based on an exact quantum dynamical model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.0689v3.pdf"}
{"id": "0711.0966", "abstract": "  Although at least one quarter of early-type barred galaxies host secondary stellar bars embedded in their large-scale primary counterparts, the dynamics of such double barred galaxies are still not well understood. Recently we reported success at simulating such systems in a repeatable way in collisionless systems. In order to further our understanding of double-barred galaxies, here we characterize the density and kinematics of the N-body simulations of these galaxies. This will facilitate comparison with observations and lead to a better understanding of the observed double-barred galaxies. We find the shape and size of our simulated secondary bars are quite reasonable compared to the observed ones. We demonstrate that an authentic decoupled secondary bar may produce only a weak twist of the kinematic minor axis in the stellar velocity field, due to the relatively large random motion of stars in the central region. We also find that the edge-on nuclear bars are probably not related to boxy peanut-shaped bulges which are most likely to be edge-on primary large-scale bars. Finally we demonstrate that the non-rigid rotation of the secondary bar causes its pattern speed not to be derived with great accuracy using the Tremaine-Weinberg method. We also compare with observations of NGC 2950, a prototypical double-barred early-type galaxy, which suggest that the nuclear bar may be rotating in the opposite sense as the primary. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.0966v1.pdf"}
{"id": "0711.1482", "abstract": "  We propose and analyze a novel dual-gate Spin Field Effect Transistor (SpinFET) with half-metallic ferromagnetic source and drain contacts. The transistor has two gate pads that can be biased independently. It can be switched ON or OFF with a few mV change in the differential bias between the two pads, resulting in extremely low dynamic power dissipation during switching. The ratio of ON to OFF conductance remains fairly large (  60) up to a temperature of 10 K. This device also has excellent inverter characteristics, making it attractive for applications in low power and high density Boolean logic circuits. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.1482v1.pdf"}
{"id": "0711.3077", "abstract": "  This paper considers the average complexity of maximum likelihood (ML) decoding of convolutional codes. ML decoding can be modeled as finding the most probable path taken through a Markov graph. Integrated with the Viterbi algorithm (VA), complexity reduction methods such as the sphere decoder often use the sum log likelihood (SLL) of a Markov path as a bound to disprove the optimality of other Markov path sets and to consequently avoid exhaustive path search. In this paper, it is shown that SLL-based optimality tests are inefficient if one fixes the coding memory and takes the codeword length to infinity. Alternatively, optimality of a source symbol at a given time index can be testified using bounds derived from log likelihoods of the neighboring symbols. It is demonstrated that such neighboring log likelihood (NLL)-based optimality tests, whose efficiency does not depend on the codeword length, can bring significant complexity reduction to ML decoding of convolutional codes. The results are generalized to ML sequence detection in a class of discrete-time hidden Markov systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.3077v3.pdf"}
{"id": "0711.3083", "abstract": "  We derive general constraints on supersymmetric extension of axion models, in particular paying careful attention to the cosmological effects of saxion. It is found that for every mass range of the saxion from keV to TeV, severe constraints on the energy density of the saxion are imposed. Together with constraints from axino we obtain stringent upper bounds on the reheating temperature. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.3083v2.pdf"}
{"id": "0711.3141", "abstract": "  We present new evolutionary synthesis models for Single Stellar Populations covering a wide range in age and metallicity. The most important difference with existing models is the use of NLTE atmosphere models for the hot stars (O, B, WR, post-AGB stars, and planetary nebulae) that have an important impact in the stellar cluster's ionizing spectra. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.3141v1.pdf"}
{"id": "0711.3164", "abstract": "  We consider the entanglement between quantum field degrees of freedom inside and outside the horizon as a plausible source of black-hole entropy. We examine possible deviations of black hole entropy from area proportionality. We show that while the area law holds when the field is in its ground state, a correction term proportional to a fractional power of area results when the field is in a superposition of ground and excited states. We compare our results with the other approaches in the literature. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.3164v1.pdf"}
{"id": "0711.4786", "abstract": "  The extended Gross-Pitaevskii equation for the Bose-Einstein condensation of gases with attractive 1/r-interaction has a second solution which is born together with the ground state in a tangent bifurcation. At the bifurcation point both states coalesce, i.e., the energies and the wave functions are identical. We investigate the bifurcation point in the context of exceptional points, a phenomenon known for linear non-Hermitian Hamiltonians. We point out that the mean field energy, the chemical potential, and the wave functions show the same behavior as an exceptional point in a linear, non-symmetric system. The analysis of the analytically continued Gross-Pitaevskii equation reveals complex waves at negative scattering lengths below the tangent bifurcation. These solutions are interpreted as a decay of the condensate caused by an absorbing potential. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.4786v1.pdf"}
{"id": "0712.0809", "abstract": "  The observed slow rotation and abundance peculiarities of certain blue horizontal branch (BHB) stars suggests that atomic diffusion can be important in their stellar atmospheres and can lead to vertical abundance stratification of chemical species in the atmosphere. To verify this hypothesis, we have undertaken an abundance stratification analysis in the atmospheres of six BHB stars, based on recently acquired McDonald-CE spectra. Our numerical simulations show that the iron abundance is vertically stratified in the atmospheres of two stars in M15: B267 and B279. One star WF2-2541 in M13 also appears to have vertically stratified iron abundance, while for WF4-3085 the signatures of iron stratification are less convincing. In all cases the iron abundances increase towards the lower atmosphere. The other two stars in our sample, WF4-3485 and B84, do not show any significant variation of iron with atmospheric depth. Our results support the idea that atomic diffusion dominates other hydrodynamic processes in the atmospheres of BHB stars. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0712/0712.0809v1.pdf"}
{"id": "0712.2298", "abstract": "  The main objective of the Penn State/Torun Centre for Astronomy Search for Planets around Evolved Stars is the detection of planetary systems around massive, evolved stars. We are also interested in the evolution of these systems on stellar evolution timescales. In this paper we present our approach to determine the basic physical parameters of our targets GK-giants. We also discuss the stellar activity indicators used in our survey: line bisector and curvature, and Halpha variability. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0712/0712.2298v1.pdf"}
{"id": "0712.2508", "abstract": "  We discuss the ground state entanglement of the E⊗ϵ Jahn-Teller model in the presence of a strong transverse magnetic field as a function of the vibronic coupling strength. A complete characterization is given of the phenomenon of entanglement sharing in a system composed by a qubit coupled to two bosonic modes. Using the residual I-tangle, we find that three-partite entanglement is significantly present in the system in the parameter region near the bifurcation point of the corresponding classical model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0712/0712.2508v1.pdf"}
{"id": "0712.2595", "abstract": "  Distinguishing logarithmic depth quantum circuits on mixed states is shown to be complete for QIP, the class of problems having quantum interactive proof systems. Circuits in this model can represent arbitrary quantum processes, and thus this result has implications for the verification of implementations of quantum algorithms. The distinguishability problem is also complete for QIP on constant depth circuits containing the unbounded fan-out gate. These results are shown by reducing a QIP-complete problem to a logarithmic depth version of itself using a parallelization technique. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0712/0712.2595v1.pdf"}
{"id": "0712.3722", "abstract": "  We study quantum systems with broken symmetry that can be modelled as cyclic three-level atoms with coexisting one- and two-photon transitions. They can be selectively optically excited to any state. As an example, we show that left- and right-handed chiral molecules starting in the same initial states can evolve into different final states by a purely dynamic transfer process. That means, left- and right-handed molecules can be distinguished purely dynamically. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0712/0712.3722v1.pdf"}
{"id": "0801.0007", "abstract": "  We investigate one-point reduction methods of finite topological spaces. These methods allow one to study homotopy theory of cell complexes by means of elementary moves of their finite models. We also introduce the notion of h-regular CW-complex, generalizing the concept of regular CW-complex, and prove that the h-regular CW-complexes, which are a sort of combinatorial-up-to-homotopy objects, are modeled (up to homotopy) by their associated finite spaces. This is accomplished by generalizing a classical result of McCord on simplicial complexes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.0007v2.pdf"}
{"id": "0801.0221", "abstract": "  Double-peaked oxygen lines in the nebular spectra of two peculiar Type Ib/c Supernovae (SN Ib/c) have been interpreted as off-axis views of a GRB-jet or unipolar blob ejections. Here we present late-time spectra of 8 SN IIb, Ib and Ic and show that this phenomenon is common and should not be so firmly linked to extraordinary explosion physics. The line profiles are most likely caused by ejecta expanding with a torus- or disk-like geometry. Double-peaked oxygen profiles are not necessarily the indicator of a mis-directed GRB jet. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.0221v2.pdf"}
{"id": "0801.0229", "abstract": "  We introduce a spin-1/2 model in three dimensions which is a generalization of the well-known Kitaev model on a honeycomb lattice. Following Kitaev, we solve the model exactly by mapping it to a theory of non-interacting fermions in the background of a static Z_2 gauge field. The phase diagram consists of a gapped phase and a gapless one, similar to the two-dimensional case. Interestingly, unlike in the two-dimensional model, in the gapless phase the gap vanishes on a contour in the k space. Furthermore, we show that the flux excitations of the gauge field, due to some local constraints, form loop like structures; such loops exist on a lattice formed by the plaquettes in the original lattice and is topologically equivalent to the pyrochlore lattice. Finally, we derive a low-energy effective Hamiltonian that can be used to study the properties of the excitations in the gapped phase. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.0229v2.pdf"}
{"id": "0801.0989", "abstract": "  We have used the RXTE and INTEGRAL satellites simultaneously to observe the High Mass X-ray binary IGR J19140+0951. The spectra obtained in the 3-80 keV range have allowed us to perform a precise spectral analysis of the system along its binary orbit. The spectral evolution confirms the supergiant nature of the companion star and the neutron star nature of the compact object. Using a simple stellar wind model to describe the evolution of the photoelectric absorption, we were able to restrict the orbital inclination angle in the range 37-75 degrees. This analysis leads to a wind mass-loss rate from the companion star of   10e-7 Msun/year, consistent with its expected spectral type. We have detected a soft excess in at least three observations, for the first time for this source. Such soft excesses have been reported in several HMXBs in the past. We discuss the possible origin of this excess, and suggest, based on its spectral properties and occurrences prior to the superior conjunction, that it may be explained as the reprocessing of the X-ray emission originating from the neutron star by the surrounding ionised gas. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.0989v1.pdf"}
{"id": "0801.3475", "abstract": "  We introduce a new braid-theoretic framework with which to understand the Legendrian and transversal classification of knots, namely a Legendrian Markov Theorem without Stabilization which induces an associated transversal Markov Theorem without Stabilization. We establish the existence of a nontrivial knot-type specific Legendrian and transversal MTWS by enhancing the Legendrian mountain range for the (2,3)-cable of a (2,3)-torus knot provided by Etnyre and Honda, and showing that elementary negative flypes allow us to move toward maximal tb value without having to use Legendrian stabilization. In doing so we obtain new ways to visualize convex tori and Legendrian divides and rulings, using tilings and braided rectangular diagrams. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0801/0801.3475v2.pdf"}
{"id": "0802.1110", "abstract": "  The structure of K^--condensed hypernuclei, which may be produced in the laboratory in strangeness-conserving processes, is investigated using an effective chiral Lagrangian for the kaon-baryon interaction, combined with a nonrelativistic baryon-baryon interaction model. It is shown that a large number of negative strangeness is needed for the formation of highly dense and deeply bound state with kaon condensates and that part of the strangeness should be carried by hyperons mixed in the nucleus. The properties of kaon-condensed hypernuclei such as the ground state energy and particle composition are discussed. Such a self-bound object has a long lifetime and may decay only through weak interaction processes. Comparison with other possible nuclear states is also made, such as kaon-condensed nuclei without mixing of hyperons and noncondensed multistrange hypernuclei. Implications of kaon-condensed hypernuclei for experiments are mentioned. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.1110v1.pdf"}
{"id": "0802.1715", "abstract": "  We present TRAPHIC, a novel radiative transfer scheme for Smoothed Particle Hydrodynamics (SPH) simulations. TRAPHIC is designed for use in simulations exhibiting a wide dynamic range in physical length scales and containing a large number of light sources. It is adaptive both in space and in angle and can be employed for application on distributed memory machines. The commonly encountered computationally expensive scaling with the number of light sources in the simulation is avoided by introducing a source merging procedure. The (time-dependent) radiative transfer equation is solved by tracing individual photon packets in an explicitly photon-conserving manner directly on the unstructured grid traced out by the set of SPH particles. To accomplish directed transport of radiation despite the irregular spatial distribution of the SPH particles, photons are guided inside cones. We present and test a parallel numerical implementation of TRAPHIC in the SPH code GADGET-2, specified for the transport of mono-chromatic hydrogen-ionizing radiation. The results of the tests are in excellent agreement with both analytic solutions and results obtained with other state-of-the-art radiative transfer codes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.1715v2.pdf"}
{"id": "0802.3554", "abstract": "  The dynamics of User Datagram Protocol (UDP) traffic over Ethernet between two computers are analyzed using nonlinear dynamics which shows that there are two clear regimes in the data flow: free flow and saturated. The two most important variables affecting this are the packet size and packet flow rate. However, this transition is due to a transcritical bifurcation rather than phase transition in models such as in vehicle traffic or theorized large-scale computer network congestion. It is hoped this model will help lay the groundwork for further research on the dynamics of networks, especially computer networks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.3554v3.pdf"}
{"id": "0803.1192", "abstract": "  We consider the static wall approximation to the dynamics of a particle bouncing on a periodically oscillating infinitely heavy plate while subject to a potential force. We assume the case of a potential given by a power of the particle's height and sinusoidal motions of the plate. We find that for powers smaller than 1 the set of escaping orbits has full Hausdorff dimension for all motions and obtain existence of elliptic island of period 2 for arbitrarily high energies for a full-measure set of motions. Moreover we obtain conditions on the potential to ensure that the total (Lebesgue) measure of elliptic islands of period 2 is either finite or infinite. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0803/0803.1192v1.pdf"}
{"id": "0803.3107", "abstract": "  We investigate a metallic zigzag carbon nanotube by means of a Hubbard model which includes both on-site and nearest neighbour interactions. Assuming weak interactions, a renormalization group analysis of the equivalent two-leg ladder followed by bosonization and refermionization results in a Gross-Neveu model with an enlarged symmetry relative to the original Hamiltonian. For the undoped case the symmetry of the Gross-Neveu model is SO(8), but for the doped case the particle-hole symmetry is broken and the symmetry reduces to SO(6). Four ground state phases are found in the undoped carbon nanotube with repulsive interactions, a d-wave Mott insulator, an s-wave Mott insulator, a p-density wave and a charge density wave. The doped case has two ground state phases, a d-wave superconductor and a phase where a p-density wave and a charge density wave co-exist. We also explore the global phase diagram with a general interaction profile and find several additional states, including a chiral current phase where current flows around the nanotube along the zigzag bonds. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0803/0803.3107v2.pdf"}
{"id": "0803.3216", "abstract": "  Quantum master equations are common tools to describe the dynamics of many-body systems open to an environment. Due to the interaction with the latter, even for the case of non-interacting electrons, the computational cost to solve these equations increases exponentially with the particle number. We propose a simple scheme, that allows to study the dynamics of N non-interacting electrons taking into account both dissipation effects and Fermi statistics, with a computational cost that scales linearly with N. Our method is based on a mapping of the many-body system to a specific set of effective single-particle systems. We provide detailed numerical results showing excellent agreement between the effective single-particle scheme and the exact many-body one, as obtained from studying the dynamics of two different systems. In the first, we study optically-induced currents in quantum rings at zero temperature, and in the second we study a linear chain coupled at its ends to two thermal baths with different (finite) temperatures. In addition, we give an analytical justification for our method, based on an exact averaging over the many-body states of the original master equations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0803/0803.3216v2.pdf"}
{"id": "0803.3952", "abstract": "  Here we address the question whether the ionized shells associated with giant HII regions can be progenitors of the larger HI shell-like objects found in the Milky Way and other spiral and dwarf irregular galaxies. We use for our analysis a sample of 12 HII shells presented recently by Relaño et al. (2005, 2007). We calculate the evolutionary tracks that these shells would have if their expansion is driven by multiple supernovae explosions from the parental stellar clusters. We find, contrary to Relaño et al. (2007), that the evolutionary tracks of their sample HII shells are inconsistent with the observed parameters of the largest and most massive neutral hydrogen supershells. We conclude that HII shells found inside giant HII regions may represent the progenitors of small or intermediate HI shells, however they cannot evolve into the largest HI objects unless, aside from the multiple supernovae explosions, an additional energy source contributes to their expansion. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0803/0803.3952v1.pdf"}
{"id": "0804.0108", "abstract": "  The NGSIM trajectory data sets provide longitudinal and lateral positional information for all vehicles in certain spatiotemporal regions. Velocity and acceleration information cannot be extracted directly since the noise in the NGSIM positional information is greatly increased by the necessary numerical differentiations. We propose a smoothing algorithm for positions, velocities and accelerations that can also be applied near the boundaries. The smoothing time interval is estimated based on velocity time series and the variance of the processed acceleration time series. The velocity information obtained in this way is then applied to calculate the density function of the two-dimensional distribution of velocity and inverse distance, and the density of the distribution corresponding to the “microscopic” fundamental diagram. Furthermore, it is used to calculate the distributions of time gaps and times-to-collision, conditioned to several ranges of velocities and velocity differences. By simulating virtual stationary detectors we show that the probability for critical values of the times-to-collision is greatly underestimated when estimated from single-vehicle data of stationary detectors. Finally, we investigate the lane-changing process and formulate a quantitative criterion for the duration of lane changes that is based on the trajectory density in normalized coordinates. Remarkably, there is a very noisy but significant velocity advantage in favor of the targeted lane that decreases immediately before the change due to anticipatory accelerations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0804/0804.0108v1.pdf"}
{"id": "0804.0360", "abstract": "  Recently, we suggested that low-energy beta-beam neutrinos can be very useful for the study of supernova neutrino interactions. In this paper, we examine the use of a such experiment for the analysis of a supernova neutrino signal. Since supernova neutrinos are oscillating, it is very likely that the terrestrial spectrum of supernova neutrinos of a given flavor will not be the same as the energy distribution with which these neutrinos were first emitted. We demonstrate the efficacy of the proposed method for untangling multiple neutrino spectra. This is an essential feature of any model aiming at gaining information about the supernova mechanism, probing proto-neutron star physics, and understanding supernova nucleosynthesis, such as the neutrino process and the r-process. We also consider the efficacy of different experimental approaches including measurements at multiple beam energies and detector configurations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0804/0804.0360v1.pdf"}
{"id": "0804.0497", "abstract": "  We study the existence, stability, and mobility of fundamental discrete solitons in two- and three-dimensional nonlinear Schroedinger lattices with a combination of cubic self-focusing and quintic self-defocusing onsite nonlinearities. Several species of stationary solutions are constructed, and bifurcations linking their families are investigated using parameter continuation starting from the anti-continuum limit, and also with the help of a variational approximation. In particular, a species of hybrid solitons, intermediate between the site- and bond-centered types of the localized states (with no counterpart in the 1D model), is analyzed in 2D and 3D lattices. We also discuss the mobility of multi-dimensional discrete solitons that can be set in motion by lending them kinetic energy exceeding the appropriately crafted Peierls-Nabarro barrier; however, they eventually come to a halt, due to radiation loss. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0804/0804.0497v1.pdf"}
{"id": "0804.0869", "abstract": "  We construct an explicit scenario whereby the same material driving inflation in the early Universe can comprise dark matter in the present Universe, using a simple quadratic potential. Following inflation and preheating, the density of inflaton/dark matter particles is reduced to the observed level by a period of thermal inflation, of a duration already invoked in the literature for other reasons. Within the context of the string landscape, one can further argue for a non-zero vacuum energy of this field, thus unifying inflation, dark matter and dark energy into a single fundamental field. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0804/0804.0869v1.pdf"}
{"id": "0804.1348", "abstract": "  Ultraviolet light curves constructed from NUV and FUV detectors on GALEX reveal large amplitude variations during the orbital period of the Low Accretion Rate Polar MQ Dra (SDSSJ1553+55). This unexpected variation from a UV source is similar to that seen and discussed in the Polar EF Eri during its low state of accretion, even though the accretion rate in MQ Dra is an order of magnitude lower than even the low state of EF Eri. The similarity in phasing of the UV and optical light curves in MQ Dra imply a similar location for the source of light. We explore the possibilities of hot spots and cyclotron emission with simple models fit to the UV, optical and IR light curves of MQ Dra. To match the GALEX light curves with a single temperature circular hot spot requires different sizes of spots for the NUV and FUV, while a cyclotron model that can produce the optical harmonics with a magnetic field near 60 MG requires multipoles with fields > 200 MG to match the UV fluxes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0804/0804.1348v1.pdf"}
{"id": "0804.2342", "abstract": "  Collective excitations spectrum of Dirac electrons in mono and bilayer graphene in the presence of a uniform magnetic field is investigated. Analytical results for inter-Landau band plasmon spectrum within the self-consistent-field approach are obtained. SdH type oscillations that are a monotonic function of the magnetic field are observed in the plasmon spectrum of both mono- and bi-layer graphene systems. The results presented are also compared with those obtained in conventional 2DEG. The chiral nature of the quasiparticles in mono and bilayer graphene system results in the observation of π and 2π Berry's phase in the SdH- type oscillations in the plasmon spectrum. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0804/0804.2342v3.pdf"}
{"id": "0804.3424", "abstract": "  By means of the variational approximation (VA) and systematic simulations, we study dynamics and stability boundaries for solitons in a two-dimensional (2D) self-attracting Bose-Einstein condensate (BEC), trapped in an optical lattice (OL) whose amplitude is subjected to the periodic time modulation (the modulation frequency, ω, may be in the range of several KHz). Regions of stability of the solitons against the collapse and decay are identified in the space of the model's parameters. A noteworthy result is that the stability limit may reach the largest (100", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0804/0804.3424v1.pdf"}
{"id": "0804.4189", "abstract": "  We demonstrate an approach to solving the coagulation equation that involves using a finite number of moments of the particle size distribution. This approach is particularly useful when only general properties of the distribution, and their time evolution, are needed. The numerical solution to the integro-differential Smoluchowski coagulation equation at every time step, for every particle size, and at every spatial location is computationally expensive, and serves as the primary bottleneck in running evolutionary models over long periods of time. The advantage of using the moments method comes in the computational time savings gained from only tracking the time rate of change of the moments, as opposed to tracking the entire mass histogram which can contain hundreds or thousands of bins depending on the desired accuracy. The collision kernels of the coagulation equation contain all the necessary information about particle relative velocities, cross-sections, and sticking coefficients. We show how arbitrary collision kernels may be treated. We discuss particle relative velocities in both turbulent and non-turbulent regimes. We present examples of this approach that utilize different collision kernels and find good agreement between the moment solutions and the moments as calculated from direct integration of the coagulation equation. As practical applications, we demonstrate how the moments method can be used to track the evolving opacity, and also indicate how one may incorporate porous particles. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0804/0804.4189v1.pdf"}
{"id": "0805.0452", "abstract": "  We consider a family of singular maps as an example of a simple model of dynamical systems exhibiting the property of robust chaos on a well defined range of parameters. Critical boundaries separating the region of robust chaos from the region where stable fixed points exist are calculated on the parameter space of the system. It is shown that the transitions to robust chaos in these systems occur either through the routes of type-I or type-III intermittency and the critical boundaries for each type of transition have been determined on the phase diagram of the system. The simplicity of these singular maps and the robustness of their chaotic dynamics make them useful ingredients in the construction of models and in applications that require reliable operation under chaos. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.0452v2.pdf"}
{"id": "0805.0709", "abstract": "  A novel model of the data selection, acquisition and analysis for a multi-purpose and multi-component high-energy-physics experiment is presented. Its departure point is the freedom and the responsibility given to the different physics groups of the experiment to impose, on the event-by-event basis, their physics-goal-optimal configurations of (i) the sub-detectors, (ii) the trigger and data acquisition system, and (iii) the reconstruction and analysis framework. Its target is to develop, in a close analogy to the construction of the gauge models in particle physics, the overall data handling scheme, in which a multi-purpose experiment becomes an association of coexistent, yet largely independent, physics-group-based sub-experiments sharing common hardware maintenance, data-acquisition, and data reconstruction resources. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.0709v1.pdf"}
{"id": "0805.1089", "abstract": "  As part of the European Supernova Collaboration we obtained extensive photometry and spectroscopy of the type Ia SN 2002dj covering epochs from 11 days before to nearly two years after maximum. Detailed optical and near-infrared observations show that this object belongs to the class of the high-velocity gradient events as indicated by Si, S and Ca lines. The light curve shape and velocity evolution of SN 2002dj appear to be nearly identical to SN 2002bo. The only significant difference is observed in the optical to near-IR colours and a reduced spectral emission beyond 6500 A. For high-velocity gradient Type Ia supernovae, we tentatively identify a faster rise to maximum, a more pronounced inflection in the V and R light curves after maximum and a brighter, slower declining late-time B light curve as common photometric properties of this class of objects. They also seem to be characterized by a different colour and colour evolution with respect to “normal” SNe Ia. The usual light curve shape parameters do not distinguish these events. Stronger, more blueshifted absorption features of intermediate-mass elements and lower temperatures are the most prominent spectroscopic features of Type Ia supernovae displaying high velocity gradients. It appears that these events burn more intermediate-mass elements in the outer layers. Possible connections to the metallicity of the progenitor star are explored. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.1089v2.pdf"}
{"id": "0805.1564", "abstract": "  We review the properties of time intervals between the crossings at a level M of a smooth stationary Gaussian temporal signal. The distribution of these intervals and the persistence are derived within the Independent Interval Approximation (IIA). These results grant access to the distribution of extrema of a general Gaussian process. Exact results are obtained for the persistence exponents and the crossing interval distributions, in the limit of large |M|. In addition, the small time behavior of the interval distributions and the persistence is calculated analytically, for any M. The IIA is found to reproduce most of these exact results and its accuracy is also illustrated by extensive numerical simulations applied to non-Markovian Gaussian processes appearing in various physical contexts. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.1564v2.pdf"}
{"id": "0805.2133", "abstract": "  We present the results of a spectroscopic investigation of 108 nearby field B-stars. We derive their key stellar parameters, V sin i, T_ eff, log g, and log g_ polar, using the same methods that we used in our previous cluster B-star survey. By comparing the results of the field and the cluster samples, we find that the main reason for the overall slower rotation of the field sample is that it contains a larger fraction of older stars than found in the (mainly young) cluster sample. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.2133v1.pdf"}
{"id": "0805.4102", "abstract": "  Using the Born-Oppenheimer approximation, we derive an effective Hamiltonian for an optomechanical system that leads to a nonlinear Kerr effect in the system's vacuum. The oscillating mirror at one edge of the optomechanical system induces a squeezing effect in the intensity spectrum of the cavity field. A near-resonant laser field is applied at the other edge to drive the cavity field, in order to enhance the Kerr effect. We also propose a quantum-nondemolition-measurement setup to monitor a system with two cavities separated by a common oscillating mirror, based on our effective Hamiltonian approach. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.4102v4.pdf"}
{"id": "0805.4322", "abstract": "  Li et al. presented a protocol [Int. Journal of Quantum Information, Vol. 4, No. 6 (2006) 899-906] for quantum key distribution based on entanglement swapping. In this protocol they use random and certain bits to construct a classical key and they claim that this key is secure. In our article we show that the protocol by Li et al. is insecure presenting a new type of attack strategy which gives an adversary full information about the key without being detected. This strategy is based on entanglement swapping, too, and manages to preserve the correlation between the measurement results of the legitimate parties. Further we present a modified version of the protocol and show that it is secure against this new attack strategy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.4322v1.pdf"}
{"id": "0805.4411", "abstract": "  “Glauber” models are used to calculate geometric quantities in the initial state of heavy ion collisions, such as impact parameter, number of participating nucleons and initial eccentricity. The four RHIC experiments have different methods for Glauber Model calculations, leading to similar results for various geometric observables. In this document, we describe an implementation of the Monte Carlo based Glauber Model calculation used by the PHOBOS experiment. The assumptions that go in the calculation are described. A user's guide is provided for running various calculations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.4411v1.pdf"}
{"id": "0805.4617", "abstract": "  Small three-dimensional strongly coupled clusters of charged particles in a spherical confinement potential arrange themselves in nested concentric shells. If the particles are immersed into a background plasma the interaction is screened. The cluster shell configuration is known to be sensitive to the screening strength. With increased screening an increased population of the inner shell(s) is observed. Here, we present a detailed analysis of the ground state shell configurations and configuration changes in a wide range of screening parameters for clusters with particle numbers N in the range of 11 to 60. We report three types of anomalous behaviors which are observed upon increase of screening, at fixed N or for an increase of N at fixed screening. The results are obtained by means of extensive first principle molecular dynamics simulations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.4617v1.pdf"}
{"id": "0806.0610", "abstract": "  We model the hot and dense strongly interacting mater produced in high energy heavy ion collisions using relativistic hydrodynamics. Several different sources of real photons produced during these collisions are considered and their relative importance is assessed. We include contributions from QCD jets, which are allowed to loose and gain energy as they proceed through the hot matter. This is treated within the AMY formalism. We obtain photon spectra, R_AA, and v_2 in agreement with measurements performed by the PHENIX collaboration. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0806/0806.0610v1.pdf"}
{"id": "0806.1032", "abstract": "  As a possible physical realization of a quantum information processor, a system with stacked self-assembled InAs quantum dots buried in GaAs in adjacent to the channel of a spin field-effect transistor has been proposed. In this system, only one of the stacked qubits, i.e. the edge qubit (the qubit closest to the channel), is measurable via \"spin-blockade measurement.\" It is shown that the state tomography of the whole chain of the qubits is still possible even under such a restricted accessibility. The idea is to make use of the entangling dynamics of the qubits. A recipe for the two-qubit system is explicitly constructed and the effect of an imperfect fidelity of the measurement is clarified. A general scheme for multiple qubits based on repeated measurements is also presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0806/0806.1032v2.pdf"}
{"id": "0806.2534", "abstract": "  Surface-enhanced Raman spectroscopy (SERS) allows single-molecule detection due to the strong field localization occurring at sharp bends or kinks of the metal-vacuum interface. An important question concerns the limits of the signal enhancement that can be achieved via a judicious design of the surface. By using a specific example of a technologically realizable nanopatterned surface, we demonstrate that while very high enhancement factors ( 10^12) can be found for an ideal surface, these are unlikely to be achieved in laboratory samples, because even a minute, inevitable rounding-off strongly suppresses the enhancement, as well as shifts the optimal frequency. Our simulations indicate that the geometric enhancement factors are unlikely to exceed  10^8 for real samples, and that it is necessary to consider the geometric uncertainty to reliably predict the frequency for maximum enhancement. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0806/0806.2534v1.pdf"}
{"id": "0806.3309", "abstract": "  We describe how the three-dimensional quantum spin Hall phase arises from the insulator phase by changing an external parameter. In 3D systems without inversion symmetry, a gapless phase should appear between the two phases with a bulk gap. The gapless points are monopoles and antimonopoles (in k space), whose topological nature is the source of this gapless phase. In general, when the external parameter is changed from the ordinary insulator phase, two monopole-antimonopole pairs are created and the system becomes gapless. The gap-closing points (monopoles and antimonopoles) then move in the k space as the parameter is changed further. They eventually annihilate in pairs, with changing partners from the pair creations, and the system opens a gap again, entering into the quantum spin Hall phase. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0806/0806.3309v2.pdf"}
{"id": "0806.4006", "abstract": "  The high value of brane tension has a crucial role in recovering Einstein's general relativity at low energies. In the framework of a recently developed formalism with variable brane tension one can pose the question, whether it was always that high? In analogy with fluid membranes, in this paper we allow for temperature dependent brane tension, according to the corresponding law established by Eötvös. For cosmological branes this assumption leads to several immediate consequences: (a) The brane Universe was created at a finite temperature T_c and scale factor a_min. (b) Both the brane tension and the 4-dimensional gravitational coupling 'constant' increase with the scale factor from zero to asymptotic values. (c) The 4-dimensional cosmological 'constant' evolves with a, starting with a huge negative value, passing through zero, finally reaching a small positive value. Such a scale-factor dependent cosmological constant is able to generate a surplus of attraction at small a (as dark matter does) and a late-time repulsion at large a (dark energy). In the particular toy model discussed here the evolution of the brane tension is compensated by energy interchange between the brane and the fifth dimension, such that the continuity equation holds for the cosmological fluid. The resulting cosmology closely mimics the standard model at late times, a decelerated phase being followed by an accelerated expansion. The energy absorption of the brane drives the 5D space-time towards maximal symmetry, becoming Anti de Sitter. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0806/0806.4006v2.pdf"}
{"id": "0807.0299", "abstract": "  It is widely known that cosmic magnetic fields, i.e. the fields of planets, stars, and galaxies, are produced by the hydromagnetic dynamo effect in moving electrically conducting fluids. It is less well known that cosmic magnetic fields play also an active role in cosmic structure formation by enabling outward transport of angular momentum in accretion disks via the magnetorotational instability (MRI). Considerable theoretical and computational progress has been made in understanding both processes. In addition to this, the last ten years have seen tremendous efforts in studying both effects in liquid metal experiments. In 1999, magnetic field self-excitation was observed in the large scale liquid sodium facilities in Riga and Karlsruhe. Recently, self-excitation was also obtained in the French \"von Karman sodium\" (VKS) experiment. An MRI-like mode was found on the background of a turbulent spherical Couette flow at the University of Maryland. Evidence for MRI as the first instability of an hydrodynamically stable flow was obtained in the \"Potsdam Rossendorf Magnetic Instability Experiment\" (PROMISE). In this review, the history of dynamo and MRI related experiments is delineated, and some directions of future work are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.0299v2.pdf"}
{"id": "0807.0390", "abstract": "  Photospheric granulation may excite transverse kink pulses in anchored vertical magnetic flux tubes. The pulses propagate upwards along the tubes with the kink speed, while oscillating wakes are formed behind the wave front in a stratified atmosphere. The wakes oscillate at the kink cut-off frequency of stratified medium and gradually decay in time. When two or more consecutive kink pulses with different polarizations propagate in the same thin tube, then the wakes corresponding to different pulses may superimpose. The superposition sets up helical motions of magnetic flux tubes in the photosphere/chromosphere as seen by recent Hinode movies. The energy carried by the pulses is enough to heat the solar chrmosphere/corona and accelerate the solar wind. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.0390v1.pdf"}
{"id": "0807.1158", "abstract": "  In the algebraic view, the solution to a network coding problem is seen as a variety specified by a system of polynomial equations typically derived by using edge-to-edge gains as variables. The output from each sink is equated to its demand to obtain polynomial equations. In this work, we propose a method to derive the polynomial equations using source-to-sink path gains as the variables. In the path gain formulation, we show that linear and quadratic equations suffice; therefore, network coding becomes equivalent to a system of polynomial equations of maximum degree 2. We present algorithms for generating the equations in the path gains and for converting path gain solutions to edge-to-edge gain solutions. Because of the low degree, simplification is readily possible for the system of equations obtained using path gains. Using small-sized network coding problems, we show that the path gain approach results in simpler equations and determines solvability of the problem in certain cases. On a larger network (with 87 nodes and 161 edges), we show how the path gain approach continues to provide deterministic solutions to some network coding problems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.1158v2.pdf"}
{"id": "0807.2092", "abstract": "  Here we address the question regarding the nature of quark gluon plasma (QGP), whether it is a liquid or strongly coupled plasma (SCP), using two different phenomenological models, namely quasi-particle model (qQGP) and strongly coupled quark gluon plasma (SCQGP). First we compare these two models, both of which explains the results of lattice simulation of quantum chromodynamics, as a function of plasma parameter and conclude that the QGP is largely (T > 1.5 T_c) SCQGP and only for T < 1.5 T_c it may be a liquid. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.2092v2.pdf"}
{"id": "0807.2437", "abstract": "  Star clusters that form in nuclear rings appear to be at slightly larger radii than the gas. We argue that the star clusters move out from the gas in which they are formed because of satellite-disk tidal interactions. In calculating the dynamics of this star cluster and gas ring system, we include the effects of dynamical friction of the background stars in the host galaxy on the star cluster, and inflowing gas along the bar onto the nuclear ring at the two contact points. We show that the final separation is of the order of the Hill radius of the nuclear ring, which is typically 20-30", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.2437v2.pdf"}
{"id": "0807.2511", "abstract": "  We study the ejecta chemistry of a zero-metallicity progenitor, massive, supernova using a novel approach based on chemical kinetics. Species considered span the range of simple, di-atomic molecules such as CO or SiO to more complex species involved in dust nucleation processes. We describe their formation from the gas phase including all possible relevant chemical processes and apply it to the ejecta of a primordial 170 Msun supernova. Two ejecta cases are explored: full mixing of the heavy elements, and a stratified ejecta reflecting the progenitor nucleosynthesis. Penetration of hydrogen from the progenitor envelope is considered. We show that molecules form very efficiently in the ejecta of primordial supernovae whatever the level of mixing and account for 13 to 34", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.2511v1.pdf"}
{"id": "0807.3495", "abstract": "  We consider a dynamical model for a Fermi gas in the Bardeen-Cooper-Schrieffer (BCS) superfluid state, trapped in a combination of a 1D or 2D optical lattice (OL) and a tight parabolic potential acting in the transverse direction(s). The model is based on an equation for the order parameter (wave function), which is derived from the energy density for the weakly coupled BCS superfluid. The equation includes a nonlinear self-repulsive term of power 7/3, which accounts for the Fermi pressure. Reducing the equation to the 1D or 2D form, we construct families of stable 1D and 2D gap solitons (GSs) by means of numerical simulations, which are guided by the variational approximation (VA). The GSs are, chiefly, compact objects trapped in a single cell of the OL potential. In the linear limit, the VA predicts almost exact positions of narrow Bloch bands that separate the semi-infinite and first finite gaps, as well as the first and second finite ones. Families of stable even and odd bound states of 1D GSs are constructed too. We also demonstrate that the GS can be dragged without much distortion by an OL moving at a moderate velocity (∼ 1 mm/s, in physical units). The predicted GSs contain ∼ 10^3-10^4 and ∼ 10^3 atoms per 1D and 2D settings, respectively. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.3495v1.pdf"}
{"id": "0807.4340", "abstract": "  We estimate the temporal change of magnetic flux perpendicular to the solar surface in a decaying active region by using a time series of the spatial distribution of vector magnetic fields in the photosphere. The vector magnetic fields are derived from full spectropolarimetric measurements with the Solar Optical Telescope aboard Hinode. We compare a magnetic flux loss rate to a flux transport rate in a decaying sunspot and its surrounding moat region. The amount of magnetic flux that decreases in the sunspot and moat region is very similar to magnetic flux transported to the outer boundary of the moat region. The flux loss rates [(dF/dt)_loss] of magnetic elements with positive and negative polarities are balanced each other around the outer boundary of the moat region. These results suggest that most of the magnetic flux in the sunspot is transported to the outer boundary of the moat region as moving magnetic features, and then removed from the photosphere by flux cancellation around the outer boundary of the moat region. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0807/0807.4340v1.pdf"}
{"id": "0808.0935", "abstract": "  The resulting stationary states and scattering properties of an effective potential brought about by embedding a quantum well in another well are investigated in this work. The composite well system is constructed via a superposition of modified Poeschl - Teller potential wells. The energy spectrum in each composite well is obtained using the shooting method and the transport of a particle above this system is analyzed using the transfer matrix method. It is shown that decreasing the size of the embedded middle well lowers the ground state energy of the well-in-a-well system. Moreover, the bound states increase in number and become more evenly spaced. In addition, the transmission probability of a free particle incident above a composite well is lowest for the system with a large embedded well as compared to well-in-a-well systems of the same depth. Small variations in designed potential wells yield different quantum mechanical features. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.0935v1.pdf"}
{"id": "0808.1758", "abstract": "  Single-walled carbon nanotubes are strongly correlated systems with large Coulomb repulsion between two electrons occupying the same p_z orbital. Within a molecular Hamiltonian appropriate for correlated π-electron systems, we show that optical excitations polarized parallel to the nanotube axes in the so-called metallic single-walled carbon nanotubes are to excitons. Our calculated absolute exciton energies in twelve different metallic single-walled carbon nanotubes, with diameters in the range 0.8 - 1.4 nm, are in nearly quantitative agreement with experimental results. We have also calculated the absorption spectrum for the (21,21) single-walled carbon nanotube in the E_22 region. Our calculated spectrum gives an excellent fit to the experimental absorption spectrum. In all cases our calculated exciton binding energies are only slightly smaller than those of semiconducting nanotubes with comparable diameters, in contradiction to results obtained within the ab initio approach, which predicts much smaller binding energies. We ascribe this difference to the difficulty of determining the behavior of systems with strong on-site Coulomb interactions within theories based on the density functional approach. As in the semiconducting nanotubes we predict in the metallic nanotubes a two-photon exciton above the lowest longitudinally polarized exciton that can be detected by ultrafast pump-probe spectroscopy. We also predict a subgap absorption polarized perpendicular to the nanotube axes below the lowest longitudinal exciton, blueshifted from the exact midgap by electron-electron interactions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.1758v2.pdf"}
{"id": "0808.1890", "abstract": "  The orbital parameters of extra-solar planets have a significant impact on the probability that the planet will transit the host star. This was recently demonstrated by the transit detection of HD 17156b whose favourable eccentricity and argument of periastron dramatically increased its transit likelihood. We present a study which provides a quantitative analysis of how these two orbital parameters affect the geometric transit probability as a function of period. Further, we apply these results to known radial velocity planets and show that there are unexpectedly high transit probabilities for planets at relatively long periods. For a photometric monitoring campaign which aims to determine if the planet indeed transits, we calculate the expected transiting planet yield and the significance of a potential null result, as well as the subsequent constraints that may be applied to orbital parameters. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.1890v1.pdf"}
{"id": "0808.2132", "abstract": "  Embedded germanium nanocrystals (NCs) in a silica host matrix are theoretically analyzed to identify their third-order bound-state nonlinearities. A rigorous atomistic pseudopotential approach is used for determining the electronic structure and the nonlinear optical susceptibilities. This study characterizing the two-photon absorption, nonlinear refractive index, and optical switching parameters reveals the full wavelength dependence from static up to the ultraviolet spectrum and the size dependence up to a diameter of 3.5 nm. Similar to Si NCs, the intensity-dependent refractive index increases with decreasing NC diameter. On the other hand, Ge NCs possess about an order of magnitude smaller nonlinear susceptibility compared to Si NCs of the same size. It is observed that the two-photon absorption threshold extends beyond the half band-gap value. This enables nonlinear refractive index tunability over a much wider wavelength range free from two-photon absorption. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.2132v1.pdf"}
{"id": "0808.2594", "abstract": "  We use hydrodynamic equations to study the formation of Faraday waves in a superfluid Fermi gas at zero temperature confined in a strongly elongated cigar-shaped trap. First, we treat the role of the radial density profile in the limit of an infinite cylindrical geometry and analytically evaluate the wavelength of the Faraday pattern. The effect of the axial confinement is fully taken into account in the numerical solution of hydrodynamic equations and shows that the infinite cylinder geometry provides a very good description of the phenomena. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.2594v2.pdf"}
{"id": "0808.2649", "abstract": "  Sand traps are used to measure Aeolian flux. Since they modify the surrounding wind velocity field their gauging represents an important challenge. We use numerical simulations under the assumption of homogeneous turbulence based on FLUENT to systematically study the flow field and trapping efficiency of one of the most common devices based on a hollow cylinder with two slits. In particular, we investigate the dependence on the wind speed, the Stokes number, the permeability of the membrane on the slit and the saltation height. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.2649v1.pdf"}
{"id": "0808.2776", "abstract": "  We review some of the most striking properties of the phase diagrams of higher dimensional black holes in pure gravity. We focus on static black hole solutions with Kaluza-Klein asymptotics and stationary black hole solutions in flat Minkowski space. Both cases exhibit a rich pattern of interconnected phases and merger points with topology changing transitions. In the first case, the phase diagram includes uniform and non-uniform black strings, localized black holes and sequences of Kaluza-Klein bubbles. In the latter case, it includes Myers-Perry black holes, black rings, black saturns and pinched black holes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.2776v2.pdf"}
{"id": "0808.3171", "abstract": "  The stopping power and energy loss rate of charged particles traversing a two-dimensional Dirac plasma is investigated. The Dirac plasma considered here models a solid state system, recently realized graphene monolayer, where the conduction electrons obey the Dirac-like equation and exhibit a linear in momentum dispersion relation. Theoretical work presented here is based on the the dielectric response function and the dynamical structure function within the Random-Phase-Approximation (RPA). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.3171v1.pdf"}
{"id": "0808.3443", "abstract": "  We present the results from arcsecond resolution observations of various line transitions at 1.3 mm toward hypercompact HII region G28.20-0.04N. With the SMA data, we have detected and mapped the transitions in the CH_3CN, CO, ^13CO, SO_2, OCS, and CH_3OH molecular lines as well as the radio recombination line H30α. The observations and analysis indicate a hot core associated with G28.20-0.04N. The outflow and possible rotation are detected in this region. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.3443v1.pdf"}
{"id": "0809.0469", "abstract": "  We solve one of the open problems in Einstein-Cartan theory, namely we find a natural matter source whose spin angular momentum tensor is compatible with the cosmological principle. We analyze the resulting evolution equations and find that an epoch of accelerated expansion is an attractor. The torsion field quickly decays in that period. Our results are interpreted in the context of the standard model of cosmology. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.0469v3.pdf"}
{"id": "0809.2772", "abstract": "  Ground-based solar polarimetry has made great progress over the last decade. Nevertheless, polarimetry is still an afterthought in most telescope and instrument designs, and most polarimeters are designed based on experience and rules of thumb rather than using more formal systems engineering approaches as is common in standard optical design efforts. Here we present the first steps in creating a set of systems engineering approaches to the design of polarimeters that makes sure that the final telescope-instrument-polarimeter system is more than the sum of its parts. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.2772v1.pdf"}
{"id": "0809.3157", "abstract": "  The recent discovery of a new class of recurrent and fast X-ray transient sources, the Supergiant Fast X-ray Transients, poses interesting questions on the possible mechanisms responsible for their transient X-ray emission. The association with blue supergiants, the spectral properties similar to those of accreting pulsars and the detection, in a few cases, of X-ray pulsations, confirm that these transients are High Mass X-ray Binaries. I review the different mechanisms proposed to explain their transient outbursts and the link to persistent wind accretors. I discuss the different models in light of the new observational results coming from an on-going monitoring campaign of four Supergiant Fast X-ray Transients with Swift. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.3157v2.pdf"}
{"id": "0809.3942", "abstract": "  Side-channel attacks are efficient attacks against cryptographic devices. They use only quantities observable from outside, such as the duration and the power consumption. Attacks against synchronous devices using electric observations are facilitated by the fact that all transitions occur simultaneously with some global clock signal. Asynchronous control remove this synchronization and therefore makes it more difficult for the attacker to insulate interesting intervals. In addition the coding of data in an asynchronous circuit is inherently more difficult to attack. This article describes the Programmable Logic Block of an asynchronous FPGA resistant against side-channel attacks. Additionally it can implement different styles of asynchronous control and of data representation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.3942v1.pdf"}
{"id": "0809.4516", "abstract": "  I discuss how the chemical abundance distributions, kinematics and age distributions of stars in the thin and thick disks of the Galaxy can be used to decipher the merger history of the Milky Way, a typical large galaxy. The observational evidence points to a rather quiescent past merging history, unusual in the context of the `consensus' cold-dark-matter cosmology favoured from observations of structure on scales larger than individual galaxies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.4516v1.pdf"}
{"id": "0809.5063", "abstract": "  We rigorously analyze Knill's Fibonacci scheme for fault-tolerant quantum computation, which is based on the recursive preparation of Bell states protected by a concatenated error-detecting code. We prove lower bounds on the threshold fault rate of .67×10^-3 for adversarial local stochastic noise, and 1.25×10^-3 for independent depolarizing noise. In contrast to other schemes with comparable proved accuracy thresholds, the Fibonacci scheme has a significantly reduced overhead cost because it uses postselection far more sparingly. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.5063v2.pdf"}
{"id": "0810.0154", "abstract": "  Statistical mechanics approach is useful not only in analyzing macroscopic system performance of wireless communication systems, but also in discussing design problems of wireless communication systems. In this paper, we discuss a design problem of spreading sequences in code-division multiple-access (CDMA) systems, as an example demonstrating the usefulness of statistical mechanics approach. We analyze, via replica method, the average mutual information between inputs and outputs of a randomly-spread CDMA channel, and discuss the optimization problem with the average mutual information as a measure of optimization. It has been shown that the average mutual information is maximized by orthogonally-invariant random Welch bound equality (WBE) spreading sequences. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.0154v1.pdf"}
{"id": "0810.2624", "abstract": "  To accommodate the seemingly \"anti-hierarchical\" properties of galaxies near the upper end of the mass function within our hierarchical paradigm, current models of galaxy evolution postulate a phase of vigorous AGN feedback at high redshift, which effectively terminates star formation by quenching the supply of cold gas. Using the SINFONI IFU on the VLT, we identified kpc-sized outflows of ionized gas in z 2-3 radio galaxies, which have the expected signatures of being powerful AGN-driven winds with the potential of terminating star formation in the massive host galaxies. The bipolar outflows contain up to few x 10^10 M_sun in ionized gas with velocities near the escape velocity of a massive galaxy. Kinetic energies are equivalent to  0.2", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.2624v1.pdf"}
{"id": "0810.3738", "abstract": "  As the Tevatron luminosity increases sophisticated selections are required to be efficient in selecting rare events among a very huge background. To cope with this problem, CDF has pushed the offline calorimeter algorithm reconstruction resolution up to Level 2 and, when possible, even up to Level 1, increasing efficiency and, at the same time, keeping under control the rates.   The CDF Run II Level 2 calorimeter trigger is implemented in hardware and is based on a simple algorithm that was used in Run I. This system has worked well for Run II at low luminosity. As the Tevatron instantaneous luminosity increases, the limitation due to this simple algorithm starts to become clear: some of the most important jet and MET (Missing ET) related triggers have large growth terms in cross section at higher luminosity. In this paper, we present an upgrade of the Level 2 Calorimeter system which makes the calorimeter trigger tower information available directly to a CPU allowing more sophisticated algorithms to be implemented in software. Both Level 2 jets and MET can be made nearly equivalent to offline quality, thus significantly improving the performance and flexibility of the jet and MET related triggers. However in order to fully take advantage of the new L2 triggering capabilities having at Level 1 the same L2 MET resolution is necessary. The new Level-1 MET resolution is calculated by dedicated hardware. This paper describes the design, the hardware and software implementation and the performance of the upgraded calorimeter trigger system both at Level 2 and Level 1. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.3738v1.pdf"}
{"id": "0810.4635", "abstract": "  The paper describes two Monte Carlo codes dedicated to muon simulations: MUSIC (MUon SImulation Code) and MUSUN (MUon Simulations UNderground). MUSIC is a package for muon transport through matter. It is particularly useful for propagating muons through large thickness of rock or water, for instance from the surface down to underground/underwater laboratory. MUSUN is designed to use the results of muon transport through rock/water to generate muons in or around underground laboratory taking into account their energy spectrum and angular distribution. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.4635v1.pdf"}
{"id": "0810.5060", "abstract": "  We reconsider both the global and local stability of solutions of continuously evolving dynamical systems from a geometric perspective. We clarify that an unambiguous definition of stability generally requires the choice of additional geometric structure that is not intrinsic to the dynamical system itself. While global Lyapunov stability is based on the choice of seminorms on the vector bundle of perturbations, we propose a definition of local stability based on the choice of a linear connection. We show how this definition reproduces known stability criteria for second order dynamical systems. In contrast to the general case, the special geometry of Lagrangian systems provides completely intrinsic notions of global and local stability. We demonstrate that these do not suffer from the limitations occurring in the analysis of the Maupertuis-Jacobi geodesics associated to natural Lagrangian systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.5060v1.pdf"}
{"id": "0811.1356", "abstract": "  The influence of electromagnetic radiation on the electron transport in a quantum channel with a single short-range scatterer is investigated using a generalized Landauer-Buttiker approach. We have shown that asymmetrical position of the scatterer leads to appearance of the direct photocurrent in the system. The dependence of the photocurrent on the electron chemical potential, the position of the scatterer, and the frequency of the radiation is studied. We have shown that the photocurrent and the photoconductance oscillate as functions of the electron chemical potential. The nature of oscillations is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.1356v2.pdf"}
{"id": "0811.1760", "abstract": "  We present hybrid PIC simulations of fast electron transport and energy deposition in pre-compressed fusion targets, taking full account of collective magnetic effects and the hydrodynamic response of the background plasma. Results on actual ignition of an imploded fast ignition configuration are shown accounting for the increased beam divergence found in recent experiments [J.S. Green et al., Phys. Rev. Lett. 100, 015003 (2008)] and the reduction of the electron kinetic energy due to profile steepening predicted by advanced PIC simulations [B. Chrisman et al. Phys. Plasmas 15, 056309 (2008)]. Target ignition is studied as a function of injected electron energy, distance of cone-tip to dense core, initial divergence and kinetic energy of the relativistic electron beam. We found that beam collimation reduces substantially the ignition energies of the cone-guided fuel configuration assumed here. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.1760v1.pdf"}
{"id": "0811.1987", "abstract": "  It is conventional wisdom that successful electroweak baryogenesis in the Minimal Supersymmetric extension of the Standard Model (MSSM) is in tension with the non-observation of electric dipole moments (EDMs), since the level of CP-violation responsible for electroweak baryogenesis is believed to generate unavoidably large EDMs. We show that CP-violation in the bino-Higgsino sector of the MSSM can account for successful electroweak baryogenesis without inducing large EDMs. This observation weakens the correlation between electroweak baryogenesis and EDMs, and makes the bino-driven electroweak baryogenesis scenario the least constrained by EDM limits. Taking this observation together with the requirement of a strongly first-order electroweak phase transition, we argue that a bino-driven scenario with a light stop is the most phenomenologically viable MSSM electroweak baryogenesis scenario. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.1987v1.pdf"}
{"id": "0811.2120", "abstract": "  We develop a nonequilibrium mode-coupling theory for uniformly sheared systems starting from microscopic, thermostatted SLLOD equations of motion. Our theory aims at describing stationary-state properties including rheological ones of sheared systems, and this is accomplished via two steps. Firstly, a set of self-consistent equations is formulated based on the projection-operator formalism and on the mode-coupling approach for the transient density correlators which measure the correlations between the density fluctuations in the initial equilibrium state and the ones at later times after the shearing force is turned on. The transient time-correlation function formalism is then used which, combined with the mode-coupling approximation, expresses stationary-state properties in terms of the transient density correlators. A detailed comparison of our theory is also presented with the related mode-coupling theory which is based on the Smoluchowski equation for Brownian particles under stationary shearing. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.2120v1.pdf"}
{"id": "0811.2180", "abstract": "  The TCP window size process appears in the modeling of the famous Transmission Control Protocol used for data transmission over the Internet. This continuous time Markov process takes its values in [0,∞), is ergodic and irreversible. It belongs to the Additive Increase Multiplicative Decrease class of processes. The sample paths are piecewise linear deterministic and the whole randomness of the dynamics comes from the jump mechanism. Several aspects of this process have already been investigated in the literature. In the present paper, we mainly get quantitative estimates for the convergence to equilibrium, in terms of the W_1 Wasserstein coupling distance, for the process and also for its embedded chain. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.2180v3.pdf"}
{"id": "0811.2770", "abstract": "  We describe a combined dynamic atmosphere and maser propagation model of SiO maser emission in Mira variables. This model rectifies many of the defects of an earlier model of this type, particularly in relation to the infra-red (IR) radiation field generated by dust and various wavelength-dependent, optically thick layers. Modelled masers form in rings with radii consistent with those found in VLBI observations and with earlier models. This agreement requires the adoption of a radio photosphere of radius approximately twice that of the stellar photosphere, in agreement with observations. A radio photosphere of this size renders invisible certain maser sites with high amplification at low radii, and conceals high-velocity shocks, which are absent in radio continuum observations. The SiO masers are brightest at an optical phase of 0.1 to 0.25, which is consistent with observed phase-lags. Dust can have both mild and profound effects on the maser emission. Maser rings, a shock and the optically thick layer in the SiO pumping band at 8.13appear to be closely associated in three out of four phase samples. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.2770v1.pdf"}
{"id": "0811.3851", "abstract": "  The retardation spectrometer aSPECT was built to measure the shape of the proton spectrum in free neutron decay with high precision. This allows us to determine the antineutrino electron angular correlation coefficient a. We aim for a precision more than one order of magnitude better than the present best value, which is Delta_a /a = 5", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.3851v1.pdf"}
{"id": "0811.3942", "abstract": "  We report optical spectroscopic observations of X-shaped radio sources with the Hobby-Eberly Telescope and Multiple-Mirror Telescope, focused on the sample of candidates from the FIRST survey presented in Paper I (Cheung 2007). A total of 27 redshifts were successfully obtained, 21 of which are new, including that of a newly identified candidate source of this type which is presented here. With these observations, the sample of candidates from Paper I is over 50", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.3942v2.pdf"}
{"id": "0812.0177", "abstract": "  A brief overview of loop quantum cosmology of homogeneous isotropic models is presented with emphasis on the origin of and subtleties associated with the resolution of big bang and big crunch singularities. These results bear out the remarkable intuition that John Wheeler had. Discussion is organized at two levels. The the main text provides a bird's eye view of the subject that should be accessible to non-experts. Appendices address conceptual and technical issues that are often raised by experts in loop quantum gravity and string theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.0177v1.pdf"}
{"id": "0812.1465", "abstract": "  Pion energy reconstruction is studied using the data collected during the 2004 ATLAS combined test beam. The strategy to extract corrections for the non-compensating nature of the ATLAS calorimeters for dead material losses and for leakage effects is discussed and assessed. The default ATLAS strategy based on a weighting technique of the energy deposits in calorimeter cells is presented and compared to a novel technique exploiting correlations among energy deposited in calorimeter layers. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.1465v1.pdf"}
{"id": "0812.1847", "abstract": "  A full particle simulation study is carried out on the electron acceleration at a collisionless, relatively low Alfven Mach number (M_A=5), perpendicular shock. Recent self-consistent hybrid shock simulations have demonstrated that the shock front of perpendicular shocks has a dynamic rippled character along the shock surface of low-Mach-number perpendicular shocks. In this paper, the effect of the rippling of perpendicular shocks on the electron acceleration is examined by means of large-scale (ion-scale) two-dimensional full particle simulations. It has been shown that a large-amplitude electric field is excited at the shock front in association with the ion-scale rippling, and that reflected ions are accelerated upstream at a localized region where the shock-normal electric field of the rippled structure is polarized upstream. The current-driven instability caused by the highly-accelerated reflected ions has a high growth rate to large-amplitude electrostatic waves. Energetic electrons are then generated by the large-amplitude electrostatic waves via electron surfing acceleration at the leading edge of the shock transition region. The present result suggests that the electron surfing acceleration is also a common feature at low-Mach-number perpendicular collisionless shocks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.1847v1.pdf"}
{"id": "0812.2503", "abstract": "  We characterize a pair of Cooper-pair boxes coupled with a fixed capacitor using spectroscopy and measurements of the ground-state quantum capacitance. We use the extracted parameters to estimate the concurrence, or degree of entanglement between the two qubits. We also present a thorough demonstration of a multiplexed quantum capacitance measurement technique, which is in principle scalable to a large array of superconducting qubits. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.2503v2.pdf"}
{"id": "0812.2815", "abstract": "  We report on optical imaging of the X-ray binary SAX J1808.4-3658 with the 8-m Gemini South Telescope. The binary, containing an accretion-powered millisecond pulsar, appears to have a large periodic modulation in its quiescent optical emission. In order to clarify the origin of this modulation, we obtained three time-resolved r'-band light curves (LCs) of the source in five days. The LCs can be described by a sinusoid, and the long time-span between them allows us to determine optical period P=7251.9 s and phase 0.671 at MJD 54599.0 (TDB; phase 0.0 corresponds to the ascending node of the pulsar orbit), with uncertainties of 2.8 s and 0.008 (90 ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.2815v1.pdf"}
{"id": "0812.2999", "abstract": "  Using a density functional approach based on a Skyrme interaction, thermodynamic properties of finite nuclei are investigated at non-zero temperture. The role of a momentum dependent isovector term is now studied besides volume, symmetry, surface and Coulomb effects. Various features associated with both mechanical and chemical instability and the liquid-gas coexistence curve are sensitive to the Skyrme interaction. The separated effects of the isoscalar term and the isovector term of momentum dependent interaction are studied for a modified SKM(m^*=m) interaction. The frequently used Skyrme interaction SLy4 is one of the cases considered and is shown to have better features for neutron star studies due to a larger symmetry energy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.2999v2.pdf"}
{"id": "0812.3514", "abstract": "  We study theoretically the non-linear response properties of glass formers. We establish several general results which, together with the assumption of Time-Temperature Superposition, lead to a relation between the non-linear response and the derivative of the linear response with respect to temperature. Using results from Mode-Coupling Theory (MCT) and scaling arguments valid close to the glass transition, we obtain the frequency and temperature dependence of the non-linear response in the α and β-regimes. Our results demonstrate that supercooled liquids are characterized by responses to external perturbations that become increasingly non-linear as the glass transition is approached. These results are extended to the case of inhomogeneous perturbing fields. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.3514v2.pdf"}
{"id": "0812.3570", "abstract": "  We studied the Adler-Bardeen-Bell-Jackiw anomaly in the context of a finite chiral quark model known as the Spectral Quark Model. Within this model, we obtain the general non-local form of the axial vertex compatible with a non vanishing axial coupling, in the chiral limit. The triangle anomaly is computed and we show that the obtained dependence of the axial vertex with the spectral mass is necessary to ensure both finiteness and the correct violation of the chiral Ward-Takahashi identity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.3570v2.pdf"}
{"id": "0812.3595", "abstract": "  A modular application of the integration by fractional expansion (IBFE) method for evaluating Feynman diagrams is extended to diagrams that contain loop triangle subdiagrams in their geometry. The technique is based in the replacement of this module or subdiagram by its corresponding multiregion expansion (MRE), which in turn is obtained from Schwinger's parametric representation of the diagram. The result is a topological reduction, transforming the triangular loop into an equivalent vertex, which simplifies the search for the MRE of the complete diagram. This procedure has important advantages with respect to considering the parametric representation of the whole diagram: the obtained MRE is reduced and the resulting hypergeometric series tend to have smaller multiplicity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.3595v3.pdf"}
{"id": "0812.4631", "abstract": "  A practical scheme is proposed for creation of continuous variable entangled cluster states of four distinct atomic ensembles located inside a high-finesse ring cavity. The scheme does not require a set of external input squeezed fields, a network of beam splitters and measurements. It is based on nothing else than the dispersive interaction between the atomic ensembles and the cavity mode and a sequential application of laser pulses of a suitably adjusted amplitudes and phases. We show that the sequential laser pulses drive the atomic \"field modes\" into pure squeezed vacuum states. The state is then examined against the requirement to belong to the class of cluster states. We illustrate the method on three examples of the entangled cluster states, the so-called continuous variable linear, square and T-type cluster states. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.4631v2.pdf"}
{"id": "0812.4960", "abstract": "  Results from molecular dynamics simulations of two viscous molecular model liquids – the Lewis-Wahnstrom model of ortho-terphenyl and an asymmetric dumbbell model – are reported. We demonstrate that the liquids have a “hidden” approximate scale invariance: Equilibrium potential energy fluctuations are accurately described by inverse power law (IPL) potentials, the radial distribution functions are accurately reproduced by the IPL's, and the radial distribution functions obey the IPL predicted scaling properties to a good approximation. IPL scaling of the dynamics also applies – with the scaling exponent predicted by the equilibrium fluctuations. In contrast, the equation of state does not obey the IPL scaling. We argue that our results are general for van der Waals liquids, but do not apply, e.g., for hydrogen-bonded liquids. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.4960v3.pdf"}
{"id": "0812.4992", "abstract": "  A large two-body scattering length leads to universal behavior in few-body systems. In particular, the three-body system displays interesting features such as exact discrete scale invariance in the bound state spectrum in the limit of infinite scattering length. Here, I will discuss how an effective field theory (EFT) can be used to study these features and how the finite range of the underlying interaction impacts the bound state spectrum at first order in the EFT expansion. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.4992v1.pdf"}
{"id": "0901.1295", "abstract": "  We analyze the observed distribution of the orbital eccentricity and period of binary radio pulsars in globular clusters using computational tools to simulate binary-single star interactions. Globular clusters have different groups of pulsars arising from separate interaction scenarios. Intermediate eccentricities of cluster pulsars can be mostly accounted by fly-bys although locally lower stellar densities at pulsar positions may alter the situation. Very high eccentricities are likely to be results of exchanges and/or mergers of single stars with the binary companion of the pulsar. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.1295v2.pdf"}
{"id": "0901.1302", "abstract": "  Black holes in equilibrium and the counting of their entropy within Loop Quantum Gravity are reviewed. In particular, we focus on the conceptual setting of the formalism, briefly summarizing the main results of the classical formalism and its quantization. We then focus on recent results for small, Planck scale, black holes, where new structures have been shown to arise, in particular an effective quantization of the entropy. We discuss recent results that employ in a very effective manner results from number theory, providing a complete solution to the counting of black hole entropy. We end with some comments on other approaches that are motivated by loop quantum gravity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.1302v1.pdf"}
{"id": "0901.2316", "abstract": "  Due to their penetrating nature, dileptons are a valuable probe for the properties of the hot and/or dense medium created in relativistic heavy-ion collisions. Dilepton invariant-mass spectra provide direct access to the properties of the electromagnetic current-correlation function in strongly interacting matter. In this paper an overview is given of our current theoretical understanding of the dilepton phenomenology in comparison to recent data in heavy-ion collisions at the CERN SPS. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.2316v2.pdf"}
{"id": "0901.3240", "abstract": "  The far-IR spectral window plays host to a wide range of both spectroscopic and photometric diagnostics with which to open the protoplanetary disks and exoplanet research to wavelengths completely blocked by the Earth's atmosphere. These include some of the key atomic (e.g., oxygen) and molecular (e.g., water) cooling lines, the dust thermal emission, the water ice features as well as many other key chemical tracers. Most of these features can not be observed from ground-based telescopes but play a critical diagnostic in a number of key areas including the early stages of planet formation and potentially exoplanets. The proposed Japanese-led IR space telescope SPICA, with its 3.5m cooled mirror will be the next step in sensitivity after Herschel. SPICA has been recently selected to go to the next stage of the ESA's Cosmic Vision 2015-2025 process. This contribution summarizes the design concept behind SAFARI: an imaging far-IR spectrometer covering the  30-210um waveband that is one of a suite of instruments for SPICA; it also highlights some of the science questions that it will be possible to address in the field of exoplanets and planet formation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.3240v1.pdf"}
{"id": "0901.4132", "abstract": "  A data acquisition (DAQ) system is described which will be used for the next generation of prototype calorimeters using particle flow algorithms for the International Linear Collider (ILC). The design is sufficiently generic and scalable such that it should have numerous applications either for ILC detectors or elsewhere within high energy physics in general. The DAQ system will be implemented using FPGAs and built using off-the-shelf components and networking hardware with programmable FPGAs. The software for the DAQ system is based on an existing framework, DOOCS, which is a server/client object-oriented system. The design philosophy, current status of the project and its aims are presented in this report. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.4132v1.pdf"}
{"id": "0901.4325", "abstract": "  The formation of compact objects like stars and black holes is strongly constrained by the requirement that nearly all of the initial angular momentum of the diffuse material from which they form must be removed or redistributed during the formation process. The mechanisms that may be involved and their implications are discussed for (1) low-mass stars, most of which probably form in binary or multiple systems; (2) massive stars, which typically form in clusters; and (3) supermassive black holes that form in galactic nuclei. It is suggested that in all cases, gravitational interactions with other stars or mass concentrations in a forming system play an important role in redistributing angular momentum and thereby enabling the formation of a compact object. If this is true, the formation of stars and black holes must be a more complex, dynamic, and chaotic process than in standard models. The gravitational interactions that redistribute angular momentum tend to couple the mass of a forming object to the mass of the system, and this may have important implications for mass ratios in binaries, the upper stellar IMF in clusters, and the masses of supermassive black holes in galaxies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.4325v4.pdf"}
{"id": "0901.4437", "abstract": "  We numerically study free expansion of a few Lieb-Liniger bosons, which are initially in the ground state of an infinitely deep hard-wall trap. Numerical calculation is carried out by employing a standard Fourier transform, as follows from the Fermi-Bose transformation for a time-dependent Lieb-Liniger gas. We study the evolution of the momentum distribution, the real-space single-particle density, and the occupancies of natural orbitals. Our numerical calculation allows us to explore the behavior of these observables in the transient regime of the expansion, where they are non-trivially affected by the particle interactions. We derive analytically (by using the stationary phase approximation) the formula which connects the asymptotic shape of the momentum distribution and the initial state. For sufficiently large times the momentum distribution coincides (up to a simple scaling transformation) with the shape of the real-space single-particle density (the expansion is asymptotically ballistic). Our analytical and numerical results are in good agreement. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0901/0901.4437v2.pdf"}
{"id": "0902.0725", "abstract": "  Axisymmetric toroidal equilibria with toroidal and poloidal rotations are solved with a specific set of source functions. The two independent solutions are associated to L and H modes. The L/H transition is regarded as a bifurcation from one equilibrium configuration to another, under strong external heating and pellet injection to shape temperature and density profiles. Because of the steep edge gradient of the H solution, large static radial electric field, zonal flow, and improved confinements, come as consequences, not causes, of the H mode. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.0725v1.pdf"}
{"id": "0902.0840", "abstract": "  Using the energy variational method of magneto-solid-mechanical theory of a perfectly conducting elastic medium threaded by magnetic field, the frequency spectrum of Lorentz-force-driven global torsional nodeless vibrations of a neutron star with Ferraro's form of axisymmetric poloidal nonhomogeneous internal and dipole-like external magnetic field is obtained and compared with that for this toroidal Alfvén mode in a neutron star with homogeneous internal and dipolar external magnetic field. The relevance of considered asteroseismic models to quasi-periodic oscillations of the X-ray flux during the ultra powerful outbursts of SGR 1806-20 and SGR 1900+14 is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.0840v7.pdf"}
{"id": "0902.1665", "abstract": "  In Part I of this paper we have presented a simple model capable of describing the localized failure of a massive structure. In this part, we discuss the identification of the model parameters from two kinds of experiments: a uniaxial tensile test and a three-point bending test. The former is used only for illustration of material parameter response dependence, and we focus mostly upon the latter, discussing the inverse optimization problem for which the specimen is subjected to a heterogeneous stress field. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.1665v1.pdf"}
{"id": "0902.1677", "abstract": "  Precision experiments at low energies probing weak interaction are a very promising and complementary tool for investigating the structure of the electro-weak sector of the standard model, and for searching for new phenomena revealing signs for an underlaying new symmetry. With the advent of new technologies in particle trapping and production of beams for exotic nuclei as well as ultracold neutrons, we expect one or two orders of magnitude gain in precision. This corresponds to the progress expected by new high luminosity B-factories or the LHC. Domains studied are β-decays where decay correlations, partial or total decay rates may reveal the nature of the left-right structure of the interaction and the investigation of discrete symmetries. Here the search for a finite electric dipole moment which, due to its CP-violating nature were sensational by itself, could shed light on the structure of the vacuum at very small distances. Last but not least ideas of a mirror world can be extended to the sector of baryons which can be studied with neutrons. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.1677v2.pdf"}
{"id": "0902.2713", "abstract": "  The present work shows a quantitative trade-off analysis of the Simbol-X Mirror Spacecraft (MSC) passive shielding, in the phase space of the various parameters: mass budget, dimension, geometry, and composition. A simplified physical (and geometrical) model of the sky screen, implemented by means of a GEANT4 simulation, has been developed to perform a performance-driven mass optimization and evaluate the residual background level on Simbol-X focal plane. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.2713v1.pdf"}
{"id": "0902.3005", "abstract": "  Since the beginning, quantum mechanics has raised major foundational and interpretative problems. Foundational research has been an important factor in the development of quantum cryptography, quantum information theory and, perhaps one day, practical quantum computers. Many believe that, in turn, quantum information theory has bearing on foundational research. This is largely related to the so-called epistemic view of quantum states, which maintains that the state vector represents information on a system and has led to the suggestion that quantum theory needs no interpretation. I will argue that this and related approaches fail to take into consideration two different explanatory functions of quantum mechanics, namely that of accounting for classically unexplainable correlations between classical phenomena and that of explaining the microscopic structure of classical objects. If interpreting quantum mechanics means answering the question, \"How can the world be for quantum mechanics to be true?\", there seems to be no way around it. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.3005v1.pdf"}
{"id": "0902.4238", "abstract": "  X-ray timing observations of accreting stellar mass black holes have shown that they can produce signals with such short time scales that we must be probing very close to the innermost stable circular orbit that is predicted by the theory of General Relativity (GR). These signals are quasi-periodic oscillations (QPOs), and both the high-frequency variety (HFQPOs, which have frequencies in the 40-450 Hz range) as well as the 0.1-10 Hz low-frequency type have the potential to provide tests of GR in the strong field limit. An important step on the path to GR tests is to constrain the physical black hole properties, and the straightforward frequency measurements that are possible with X-ray timing may provide one of the cleanest measurements of black hole spins. While current X-ray satellites have uncovered these phenomenona, the HFQPOs are weak signals, and future X-ray timing missions with larger effective area are required for testing the candidate theoretical QPO mechanisms. Another main goal in the study of accreting black holes is to understand the production of relativistic jets. Here, we have also made progress during the past decade by finding clear connections between the radio emission that traces the strength of the jet and the properties of the X-ray emission. With new radio capabilities just coming on-line, continuing detailed X-ray studies of accreting black holes is crucial for continuing to make progress. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.4238v1.pdf"}
{"id": "0903.1060", "abstract": "  The trace anomaly of gluodynamics on the lattice shows clear fingerprints of a dimension two condensate above the phase transition. The condensate manifests itself through even powers of the inverse temperature while the total perturbative contribution corresponds to a mild temperature dependence and turns out to be compatible with zero within errors. We try several resummation methods based on a renormalization group improvement. The trace anomaly data are analyzed and compared with other determinations of the dimension two condensate based on the Polyakov loop and the heavy qq free energy, yielding roughly similar numerical values. The role of glueballs near the transition is also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.1060v2.pdf"}
{"id": "0903.1292", "abstract": "  We perform N-body simulations of theories with infinite-volume extra dimensions, such as the Dvali-Gabadadze-Porrati (DGP) model and its higher-dimensional generalizations, where 4D gravity is mediated by massive gravitons. The longitudinal mode of these gravitons mediates an extra scalar force, which we model as a density-dependent modification to the Poisson equation. This enhances gravitational clustering, particularly on scales that have undergone mild nonlinear processing. While the standard non-linear fitting algorithm of Smith et al. overestimates this power enhancement on non-linear scales, we present a modified fitting formula that offers a remarkably good fit to our power spectra. Due to the uncertainty in galaxy bias, our results are consistent with precision power spectrum determinations from galaxy redshift surveys, even for graviton Compton wavelengths as small as 300 Mpc. Our model is sufficiently general that we expect it to capture the phenomenology of a wide class of related higher-dimensional gravity scenarios. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.1292v4.pdf"}
{"id": "0903.1536", "abstract": "  Brillouin light scattering spectroscopy is a powerful technique which incorporates several extensions such as space-, time-, phase- and wave-vector resolution.   Here, we report on the improvement of the wave-vector resolution by including an electro-optical modulator. This provides a reference to calibrate the position of the diaphragm hole which is used for wave-vector selection. The accuracy of this calibration is only limited by the accuracy of the wave-vector measurement itself. To demonstrate the validity of the approach the wave vectors of dipole-dominated spin waves excited by a microstrip antenna were measured. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.1536v1.pdf"}
{"id": "0903.2447", "abstract": "  Spin-exchange relaxation free alkali-metal magnetometers typically operate in the regime of high optical density, presenting challenges for simple and efficient optical pumping and detection. We describe a high-sensitivity Rb magnetometer using a single elliptically-polarized off-resonant laser beam. Circular component of the light creates relatively uniform spin polarization while the linear component is used to measure optical rotation generated by the atoms. Modulation of the atomic spin direction with an oscillating magnetic field shifts the detected signal to high frequencies. Using a fiber-coupled DFB laser we achieve magnetic field sensitivity of 7 fT/√()", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.2447v1.pdf"}
{"id": "0903.3425", "abstract": "  Using a segmented ion trap with mK laser-cooled ions we have realised a novel single ion source which can deterministically deliver a wide range of ion species, isotopes or ionic molecules [Schnitzler et al., Phys. Rev. Lett. 102, 070501 (2009)]. Experimental data is discussed in detail and compared with numerical simulations of ion trajectories. For the novel ion source we investigate numerically the influence of various extraction parameters on fluctuations in velocity and position of the beam. We present specialized ion optics and show from numerical simulations that nm resolution is achievable. The Paul trap, which is used as a single ion source, together with the presented ion optics, constitutes a promising candidate for a deterministic ion implantation method for applications in solid state quantum computing or classical nano-electronic devices. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.3425v3.pdf"}
{"id": "0903.4215", "abstract": "  Multipotent stem or progenitor cells undergo a sequential series of binary fate decisions, which ultimately generate the diversity of differentiated cells. Efforts to understand cell fate control have focused on simple gene regulatory circuits that predict the presence of multiple stable states, bifurcations and switch-like transitions. However, existing gene network models do not explain more complex properties of cell fate dynamics such as the hierarchical branching of developmental paths. Here, we construct a generic minimal model of the genetic regulatory network controlling cell fate determination, which exhibits five elementary characteristics of cell differentiation: stability, directionality, branching, exclusivity, and promiscuous expression. We argue that a modular architecture comprising repeated network elements reproduces these features of differentiation by sequentially repressing selected modules and hence restricting the dynamics to lower dimensional subspaces of the high-dimensional state space. We implement our model both with ordinary differential equations (ODEs), to explore the role of bifurcations in producing the one-way character of differentiation, and with stochastic differential equations (SDEs), to demonstrate the effect of noise on the system. We further argue that binary cell fate decisions are prevalent in cell differentiation due to general features of the underlying dynamical system. This minimal model makes testable predictions about the structural basis for directional, discrete and diversifying cell phenotype development and thus can guide the evaluation of real gene regulatory networks that govern differentiation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.4215v3.pdf"}
{"id": "0903.4776", "abstract": "  FLRW models filled with just dark energy are shown to have a finite past, since causal geodesics cannot be extended beyond a certain proper time. It is shown that curvature measured along causal geodesics becomes infinity on travelling to the past, though curvature scalars tend to zero. Furthermore the time measured by free-falling observers from coincidence time to Big Rip is shown to be as short as wished by increasing their linear momentum. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.4776v1.pdf"}
{"id": "0903.4779", "abstract": "  We consider a family of spherical three dimensional spacelike slices embedded in the Schwarzschild solution. The mean curvature is constant on each slice but can change from slice to slice. We give a simple expression for an everywhere positive lapse and thus we show how to construct foliations. There is a barrier preventing the mean curvature from becoming large, and we show how to avoid this so as to construct a foliation where the mean curvature runs all the way from zero to infinity. No foliation exists where the mean curvature goes from minus to plus infinity. There are slicings, however, where each slice passes through the bifurcation sphere R = 2M and the lapse only vanishes at this one point, and is positive everywhere else, while the mean curvature does run from minus to plus infinity. Symmetric foliations of the extended Schwarzschild spacetime degenerate at a critical point, where we show that the lapse function exponentially approaches zero. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.4779v2.pdf"}
{"id": "0903.5030", "abstract": "  We examine the propagation of collisionless particles emitted from a spherical shell to infinity. The number distribution at infinity, calculated as a function of the polar angle, exhibits a small deviation from uniformity. The number of particles moving from the polar region toward the equatorial plane is slightly larger than that of particles in the opposite direction, for an emission radius > 4.5M in extreme Kerr space-time. This means that the black hole spin exerts an anti-collimation effect on the particles stream propagating along the rotation axis. We also confirm this property in the weak field limit. The quadrupole moment of the central object produces a force toward the equatorial plane. For a smaller emission radius r<4.5M, the absorption of particles into the black hole, the non-uniformity and/or the anisotropy of the emission distribution become much more important. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.5030v1.pdf"}
{"id": "0903.5444", "abstract": "  We design receding horizon control strategies for stochastic discrete-time linear systems with additive (possibly) unbounded disturbances, while obeying hard bounds on the control inputs. We pose the problem of selecting an appropriate optimal controller on vector spaces of functions and show that the resulting optimization problem has a tractable convex solution. Under the assumption that the zero-input and zero-noise system is asymptotically stable, we show that the variance of the state is bounded when enforcing hard bounds on the control inputs, for any receding horizon implementation. Throughout the article we provide several examples that illustrate how quantities needed in the formulation of the resulting optimization problems can be calculated off-line, as well as comparative examples that illustrate the effectiveness of our control strategies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0903/0903.5444v3.pdf"}
{"id": "0904.0764", "abstract": "  Recently doubts have been raised about the ability of pilot wave theories with field ontology to recover the predictions of quantum field theory. In particular, Struyve has questioned that the overlap between wave functionals of macroscopically different states with fixed particle number is really non-significant. With numerical computations and some further plausibility arguments we show that the overlap between n-particle states in field theory decreases almost exponentially with the number of particles and becomes non-significant already for small particle numbers. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0904/0904.0764v4.pdf"}
{"id": "0904.0936", "abstract": "  We present a transport equation for the incoherent propagation of radiation inside a quasi-resonant atomic gas at low temperature. The derivation is based on a generalized Bethe-Salpeter equation taking into account the motion of the atoms. The obtained equation is similar to the radiative transfer equation. It is solved numerically by an original Monte Carlo approach in the case of a slab geometry. The partial frequency redistribution caused by the small velocity of the scatterers make the emitted flux outside the system and the energy density inside the medium to behave differently than in the case of complete frequency redistribution. In particular, the long time dependence of the specific intensity (escape factor) is slightly different from the Holstein prediction. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0904/0904.0936v1.pdf"}
{"id": "0904.1821", "abstract": "  We present the results of X-ray spectral analysis of the superbubble around the OB association LH9 in the H II complex N11 in the Large Magellanic Cloud. Using observations from Suzaku, we have modeled the X-ray emission over the energy range 0.2-7.5 keV. We constrained the thermal spectrum below 2 keV using a thermal plasma model found in a previous XMM-Newton study of the N11 region. We find that the hard X-ray emission (> 2 keV) requires a nonthermal power-law component. The photon index of this component was found to be Γ=1.72± 0.15. We performed an energy budget analysis for N11 using the known stellar content of LH9. We found that the observed thermal and kinetic energy in the superbubble is only half of the expected mechanical energy injected by stars. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0904/0904.1821v1.pdf"}
{"id": "0904.3340", "abstract": "  The compression-complexity trade-off of lossy compression algorithms that are based on a random codebook or a random database is examined. Motivated, in part, by recent results of Gupta-Verdú-Weissman (GVW) and their underlying connections with the pattern-matching scheme of Kontoyiannis' lossy Lempel-Ziv algorithm, we introduce a non-universal version of the lossy Lempel-Ziv method (termed LLZ). The optimality of LLZ for memoryless sources is established, and its performance is compared to that of the GVW divide-and-conquer approach. Experimental results indicate that the GVW approach often yields better compression than LLZ, but at the price of much higher memory requirements. To combine the advantages of both, we introduce a hybrid algorithm (HYB) that utilizes both the divide-and-conquer idea of GVW and the single-database structure of LLZ. It is proved that HYB shares with GVW the exact same rate-distortion performance and implementation complexity, while, like LLZ, requiring less memory, by a factor which may become unbounded, depending on the choice or the relevant design parameters. Experimental results are also presented, illustrating the performance of all three methods on data generated by simple discrete memoryless sources. In particular, the HYB algorithm is shown to outperform existing schemes for the compression of some simple discrete sources with respect to the Hamming distortion criterion. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0904/0904.3340v1.pdf"}
{"id": "0904.3744", "abstract": "  We construct approximate kink solutions of supersymmetric open string field theory at lowest level when non-local operators in the tachyon effective action are fully taken into account. To this purpose we derive two duplication formulae for products of incomplete gamma functions, which determine the level of approximation of the solutions. The time kink is an instanton of the Euclidean theory with a well-defined tunneling probability. The spatial kink solution represents an unstable D9-brane decaying into a stable D8-brane. We calculate the ratio of the brane tensions, which almost exactly reproduces the expected value. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0904/0904.3744v2.pdf"}
{"id": "0904.3968", "abstract": "  A thermodynamic argument is proposed in order to discuss the most appropriate form of the local energy balance equation within the Oberbeck-Boussinesq approximation. The study is devoted to establish the correct thermodynamic property to be used in order to express the relationship between the change of internal energy and the temperature change. It is noted that, if the fluid is a perfect gas, this property must be identified with the specific heat at constant volume. If the fluid is a liquid, a definitely reliable approximation identifies this thermodynamic property with the specific heat at constant pressure. No explicit pressure work term must be present in the energy balance. The reasoning is extended to the case of fluid saturated porous media. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0904/0904.3968v1.pdf"}
{"id": "0904.4062", "abstract": "  The semi-classical data attached to stacks of algebroids in the sense of Kashiwara and Kontsevich are Maurer-Cartan elements on complex manifolds, which we call extended Poisson structures as they generalize holomorphic Poisson structures. A canonical Lie algebroid is associated to each Maurer-Cartan element. We study the geometry underlying these Maurer-Cartan elements in the light of Lie algebroid theory. In particular, we extend Lichnerowicz-Poisson cohomology and Koszul-Brylinski homology to the realm of extended Poisson manifolds; we establish a sufficient criterion for these to be finite dimensional; we describe how homology and cohomology are related through the Evens-Lu-Weinstein duality module; and we describe a duality on Koszul-Brylinski homology, which generalizes the Serre duality of Dolbeault cohomology. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0904/0904.4062v2.pdf"}
{"id": "0905.0984", "abstract": "  We compare localization properties of one-dimensional Frenkel excitons with Gaussian and Lorentzian uncorrelated diagonal disorder. We focus on the states of the Lifshits tail, which dominate the optical response and low-temperature energy transport in molecular J-aggregates. The absence of exchange narrowing in chains with Lorentzian disorder is shown to manifest itself in the disorder scaling of the localization length distribution. Also, we show that the local exciton level structure of the Lifshits tail differs substantially for these two types of disorder: In addition to the singlets and doublets of localized states near the bare band edge, strongly resembling those found for Gaussian disorder, for Lorentzian disorder two other types of states are found in this energy region as well, namely multiplets of three or four states localized on the same chain segment and isolated states localized on short segments. Finally, below the Lifshits tail, Lorentzian disorder induces strongly localized exciton states, centered around low energy sites, with localization properties that strongly depend on energy. For Gaussian disorder with a magnitude that does not exceed the exciton bandwidth, the likelihood to find such very deep states is exponentially small. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.0984v1.pdf"}
{"id": "0905.1477", "abstract": "  We investigate the role of size quantization in the vacuum force between metallic films of nanometric thickness. The force is calculated by the Lifshitz formula with the film dielectric tensor derived from the one-electron energies and wavefunctions under the assumption of a constant potential inside the film and a uniform distribution of the positive ion charge. The results show that quantization effects tend to reduce the force with respect to the continuum plasma model. The reduction is more significant at low electron densities and for film size of the order of few nanometers and persists for separation distances up to 10 nm. Comparison with previous work indicates that the softening of the boundary potential is important in determining the amount of the reduction. The calculations are extended to treat Drude intraband absorption. It is shown that the inclusion of relaxation time enhances the size quantization effects in the force calculations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.1477v1.pdf"}
{"id": "0905.2076", "abstract": "  We study the spin-dependent electronic excitations in alkali-metal nanoparticles. Using numerical and analytical approaches, we focus on the resonances in the response to spin-dependent dipole fields. In the spin-dipole absorption spectrum for closed-shell systems, we investigate in detail the lowest-energy excitation, the \"surface paramagnon\" predicted by L. Serra et al. [Phys. Rev. A 47, R1601 (1993)]. We estimate its frequency from simple assumptions for the dynamical magnetization density. In addition, we numerically determine the dynamical magnetization density for all low-energy spin-dipole modes in the spectrum. Those many-body excitations can be traced back to particle-hole excitations of the noninteracting system. Thus, we argue that the spin-dipole modes are not of collective nature. In open-shell systems, the spin-dipole response to an electrical dipole field is found to increase proportionally with the ground-state spin polarization. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.2076v1.pdf"}
{"id": "0905.3216", "abstract": "  We investigate the effect of single and multiple impurities on the Zeeman-localized, spin polarized bound states in dilute magnetic semiconductor hybrid system. Such bound states appear whenever a dilute magnetic semiconductor showing giant Zeeman effect is exposed to an external magnetic field showing nanoscale inhomogeneity. We consider the specific example of a superconductor-dilute magnetic semiconductor hybrid, calculate the energy spectrum and the wave functions of the bound states in the presence of a single impurity, and monitor the evolution of the bound state as a function of the impurity strength and impurity location with respect to the center of the Zeeman trapping potential. Our results have important experimental implications as they predict robust spin textures even for than than ideal samples. We find that for all realistic impurity strengths the Zeeman bound state survives the presence of the impurity. We also investigate the effect of a large number of impurities and perform ensemble averages with respect to the impurity locations. We find that the spin polarized Zeeman bound states are very robust, and they remain bound to the external field inhomogeneity throughout the experimentally relevant region of impurity concentration and scattering strength. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.3216v1.pdf"}
{"id": "0905.4731", "abstract": "  We present a new technique for measuring the abundance of europium, a representative r-process element, in solar-metallicity stars. Our algorithm compares LTE synthetic spectra with high-resolution observational spectra using a chi-square-minimization routine. The analysis is fully automated, and therefore allows consistent measurement of blended lines even across very large stellar samples. We compare our results with literature europium abundance measurements and find them to be consistent; we also find our method generates smaller errors. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.4731v2.pdf"}
{"id": "0905.4878", "abstract": "  We consider the dynamics of a disordered p-spin model with p=2, analyzing the dynamics within Ruelle's thermodynamic formalism, We use an indicator of the dynamical activity to construct the relevant dynamical Gibbs ensemble. We prove that the dynamics in the low-temperature (spin glass) phase of the model take place at a second-order phase transition between dynamically active and inactive trajectories. We also show that the same behaviour is found in a related model of a three-dimensional ferromagnet. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.4878v1.pdf"}
{"id": "0906.0016", "abstract": "  In this paper we study the entanglement properties of free non-relativistic Bose gases. At zero temperature, we calculate the bipartite block entanglement entropy of the system, and find it diverges logarithmically with the particle number in the subsystem. For finite temperatures, we study the mutual information between the two blocks. We first analytically study an infinite-range hopping model, then numerically study a set of long-range hopping models in one-deimension that exhibit Bose-Einstein condensation. In both cases we find that a Bose-Einstein condensate, if present, makes a divergent contribution to the mutual information which is proportional to the logarithm of the number of particles in the condensate in the subsystem. The prefactor of the logarithmic divergent term is model dependent. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.0016v2.pdf"}
{"id": "0906.0953", "abstract": "  The UTfit Collaboration has produced several analyses in the context of flavour physics both within and beyond the Standard Model. In this paper we present updated results for the Standard Model analysis of the Unitarity Triangle using the latest experimental and lattice QCD inputs, as well as an update of the Unitarity Triangle analysis in a scenario beyond the Standard Model. Combining all available experimental and theoretical information on Δ F=2 processes and using a model-independent parameterization, we extract the allowed New Physics contributions in the K^0, D^0, B_d, and B_s sectors. We observe a departure of the B_s mixing phase from the Standard Model expectation with a significance of about 3σ. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.0953v2.pdf"}
{"id": "0906.1418", "abstract": "  In this paper we address practical aspects of the implementation of the 0-1 test for chaos in deterministic systems. In addition, we present a new formulation of the test which significantly increases its sensitivity. The test can be viewed as a method to distill a binary quantity from the power spectrum. The implementation is guided by recent results from the theoretical justification of the test as well as by exploring better statistical methods to determine the binary quantities. We give several examples to illustrate the improvement. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.1418v1.pdf"}
{"id": "0906.2013", "abstract": "  Among various approaches for indirect detection of dark matter, synchrotron emission due to secondary electrons/positrons produced in galactic WIMPs annihilation is raising an increasing interest. In this paper we propose a new method to derive bounds in the mchi - <sigmaA*v> plane by using radio continuum observations of Messier 33, paying particular attention to a low emitting Radio Cavity. The comparison of the expected radio emission due to the galactic dark matter distribution with the observed one provides bounds which are comparable to those obtained from a similar analysis of the Milky Way. Remarkably, the present results are simply based on archival data and thus largely improvable by means of specifically tailored observations. The potentiality of the method compared with more standard searches is discussed by considering the optimistic situation of a vanishing flux (within the experimental sensitivity) measured inside the cavity by a high resolution radio telescope like ALMA. Under the best conditions our technique is able to produce bounds which are comparable to the ones expected after five years of Fermi LAT data taking for an hadronic annihilation channel. Furthermore, it allows to test the hypothesis that space telescopes like Pamela and Fermi LAT are actually observing electrons and positrons due to galactic dark matter annihilation into leptons. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.2013v2.pdf"}
{"id": "0906.2340", "abstract": "  A large set of high precision full-Stokes spectropolarimetric observations of the He-D3 line in spicules has been recorded with the ZIMPOL polarimeter at the Gregory-Coude Telescope in Locarno. The observational technique allow us to obtain measurements free from seeing induced spurious effects. The instrumental polarization is well under control and taken into account in the data analysis. The observed Stokes profiles are interpreted according to the quantum theory of the Hanle and Zeeman effects with the aim of obtaining information on the magnetic field vector. To this end, we make use of a suitable Stokes inversion technique. The results are presented giving emphasis on a few particularly interesting measurements which show clearly the operation of the Hanle and Zeeman effects in solar chromospheric spicules. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.2340v1.pdf"}
{"id": "0906.2411", "abstract": "  The peculiar velocity of the Local Group, reconstructed from inhomogeneities in the local density field, differs in direction and magnitude from the velocity inferred from the Cosmic Microwave Background dipole. We investigate whether generalized theories of gravity, which predict a modified growth of perturbations, are able to alleviate this discrepancy. We introduce a general formalism for calculating the real-space peculiar-velocity field for modified gravity and theories with interactions in the dark sector. For different classes of theories - scalar tensor and higher-dimensional gravity - we reconstruct the Local Group peculiar velocity using groups of galaxies identified in the 2MASS Redshift Survey. We show that, for realistic parameters, modifications to General Relativity cannot account for the angular discrepancy between the reconstructed Local Group velocity and the dipole in the Cosmic Microwave Background. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.2411v1.pdf"}
{"id": "0906.3406", "abstract": "  In the hot, dense plasma of solar and stellar interiors, Coulomb potentials are screened, resulting in increased nuclear reaction rates. Although Salpeter's approximation for static screening is widely accepted and used in stellar modeling, the question of screening in nuclear reactions has been revisited. In particular the issue of dynamic effects has been raised by Shaviv and Shaviv who apply the techniques of molecular dynamics to the conditions in the Sun's core in order to numerically determine the effect of screening. By directly calculating the motion of ions and electrons due to Coulomb interactions, the simulations are used to compute the effect of screening without the mean-field assumption inherent in Salpeter's approximation. In this paper we reproduce their numerical analysis of the screening energy in the plasma of the solar core and conclude that the effects of dynamic screening are relevant and should be included when stellar nuclear reaction rates are computed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.3406v1.pdf"}
{"id": "0906.3590", "abstract": "  Variable selection for high-dimensional linear models has received a lot of attention lately, mostly in the context of l1-regularization. Part of the attraction is the variable selection effect: parsimonious models are obtained, which are very suitable for interpretation. In terms of predictive power, however, these regularized linear models are often slightly inferior to machine learning procedures like tree ensembles. Tree ensembles, on the other hand, lack usually a formal way of variable selection and are difficult to visualize. A Garrote-style convex penalty for trees ensembles, in particular Random Forests, is proposed. The penalty selects functional groups of nodes in the trees. These could be as simple as monotone functions of individual predictor variables. This yields a parsimonious function fit, which lends itself easily to visualization and interpretation. The predictive power is maintained at least at the same level as the original tree ensemble. A key feature of the method is that, once a tree ensemble is fitted, no further tuning parameter needs to be selected. The empirical performance is demonstrated on a wide array of datasets. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.3590v1.pdf"}
{"id": "0906.3654", "abstract": "  Chemotactic cells of eukaryotic organisms are able to accurately sense shallow chemical concentration gradients using cell-surface receptors. This sensing ability is remarkable as cells must be able to spatially resolve small fractional differences in the numbers of particles randomly arriving at cell-surface receptors by diffusion. An additional challenge and source of uncertainty is that particles, once bound and released, may rebind the same or a different receptor, which adds to noise without providing any new information about the environment. We recently derived the fundamental physical limits of gradient sensing using a simple spherical-cell model, but not including explicit particle-receptor kinetics. Here, we use a method based on the fluctuation-dissipation theorem (FDT) to calculate the accuracy of gradient sensing by realistic receptors. We derive analytical results for two receptors, as well as two coaxial rings of receptors, e.g. one at each cell pole. For realistic receptors, we find that particle rebinding lowers the accuracy of gradient sensing, in line with our previous results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.3654v1.pdf"}
{"id": "0906.4351", "abstract": "  We study the conductance through two types of graphene nanostructures: nanoribbon junctions in which the width changes from wide to narrow, and curved nanoribbons. In the wide-narrow structures, substantial reflection occurs from the wide-narrow interface, in contrast to the behavior of the much studied electron gas waveguides. In the curved nanoribbons, the conductance is very sensitive to details such as whether regions of a semiconducting armchair nanoribbon are included in the curved structure – such regions strongly suppress the conductance. Surprisingly, this suppression is not due to the band gap of the semiconducting nanoribbon, but is linked to the valley degree of freedom. Though we study these effects in the simplest contexts, they can be expected to occur for more complicated structures, and we show results for rings as well. We conclude that experience from electron gas waveguides does not carry over to graphene nanostructures. The interior interfaces causing extra scattering result from the extra effective degrees of freedom of the graphene structure, namely the valley and sublattice pseudospins. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.4351v2.pdf"}
{"id": "0906.5534", "abstract": "  We study how the electronic structure of the bilayer graphene (BLG) is changed by electric field and strain from ab initio density-functional calculations using the LMTO and the LAPW methods. Both hexagonal and Bernal stacked structures are considered. The BLG is a zero-gap semiconductor like the isolated layer of graphene. We find that while strain alone does not produce a gap in the BLG, an electric field does so in the Bernal structure but not in the hexagonal structure. The topology of the bands leads to Dirac circles with linear dispersion in the case of the hexagonally stacked BLG due to the interpenetration of the Dirac cones, while for the Bernal stacking, the dispersion is quadratic. The size of the Dirac circle increases with the applied electric field, leading to an interesting way of controlling the Fermi surface. The external electric field is screened due to polarization charges between the layers, leading to a reduced size of the band gap and the Dirac circle. The screening is substantial in both cases and diverges for the Bernal structure for small fields as has been noted by earlier authors. As a biproduct of this work, we present the tight-binding parameters for the free-standing single layer graphene as obtained by fitting to the density-functional bands, both with and without the slope constraint for the Dirac cone. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.5534v1.pdf"}
{"id": "0907.0434", "abstract": "  An analysis of the gravitational instability in presence of dissipative effects is addressed. In particular, the standard Jeans Mechanism and the generalization in treating the Universe expansion are both analyzed when bulk viscosity affects the first-order Newtonian dynamics. As results, the perturbation evolution is founded to be damped by dissipative processes and the top-down mechanism of structure fragmentation is suppressed. In such a scheme, the value of the Jeans Mass remains unchanged also in presence of viscosity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.0434v2.pdf"}
{"id": "0907.0901", "abstract": "  Many complex networks are described by directed links; in such networks, a link represents, for example, the control of one node over the other node or unidirectional information flows. Some centrality measures are used to determine the relative importance of nodes specifically in directed networks. We analyze such a centrality measure called the influence. The influence represents the importance of nodes in various dynamics such as synchronization, evolutionary dynamics, random walk, and social dynamics. We analytically calculate the influence in various networks, including directed multipartite networks and a directed version of the Watts-Strogatz small-world network. The global properties of networks such as hierarchy and position of shortcuts, rather than local properties of the nodes, such as the degree, are shown to be the chief determinants of the influence of nodes in many cases. The developed method is also applicable to the calculation of the PageRank. We also numerically show that in a coupled oscillator system, the threshold for entrainment by a pacemaker is low when the pacemaker is placed on influential nodes. For a type of random network, the analytically derived threshold is approximately equal to the inverse of the influence. We numerically show that this relationship also holds true in a random scale-free network and a neural network. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.0901v2.pdf"}
{"id": "0907.1699", "abstract": "  We study the stochastic parallel dynamics of Ising spin systems defined on finitely connected directed random graphs with arbitrary degree distributions, using generating functional analysis. For fully asymmetric graphs the dynamics of the system can be completely solved, due to the asymptotic absence of loops. For arbitrary graph symmetry, we solve the dynamics exactly for the first few time steps, and we construct approximate stationary solutions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.1699v2.pdf"}
{"id": "0907.1857", "abstract": "  This paper concerns the elastic structures which exhibit non-zero strain at free equilibria. Many growing tissues (leaves, flowers or marine invertebrates) attain complicated configurations during their free growth. Our study departs from the 3d incompatible elasticity theory, conjectured to explain the mechanism for the spontaneous formation of non-Euclidean metrics.   Recall that a smooth Riemannian metric on a simply connected domain can be realized as the pull-back metric of an orientation preserving deformation if and only if the associated Riemann curvature tensor vanishes identically. When this condition fails, one seeks a deformation yielding the closest metric realization. We set up a variational formulation of this problem by introducing the non-Euclidean version of the nonlinear elasticity functional, and establish its Γ-convergence under the proper scaling. As a corollary, we obtain new necessary and sufficient conditions for existence of a W^2,2 isometric immersion of a given 2d metric into ℝ^3. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.1857v1.pdf"}
{"id": "0907.2355", "abstract": "  We study the influence of composition changes on the glass transition of binary hard disc and hard sphere mixtures in the framework of mode coupling theory. We derive a general expression for the slope of a glass transition line. Applied to the binary mixture in the low concentration limits, this new method allows a fast prediction of some properties of the glass transition lines. The glass transition diagram we find for binary hard discs strongly resembles the random close packing diagram. Compared to 3D from previous studies, the extension of the glass regime due to mixing is much more pronounced in 2D where plasticization only sets in at larger size disparities. For small size disparities we find a stabilization of the glass phase quadratic in the deviation of the size disparity from unity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.2355v1.pdf"}
{"id": "0907.2502", "abstract": "  We consider the efficiency of chemical energy extraction from the environment by the growth of a copolymer made of two constituent units in the entropy-driven regime. We show that the thermodynamic nonlinearity associated with the information processing aspect is responsible for a branching of the system properties such as power, speed of growth, entropy production, and efficiency, with varying affinity. The standard linear thermodynamics argument which predicts an efficiency of 1/2 at maximum power is inappropriate because the regime of maximum power is located either outside of the linear regime or on a separate bifurcated branch, and because the usual thermodynamic force is not the natural variable for this optimization. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.2502v1.pdf"}
{"id": "0907.2900", "abstract": "  We study bar formation in galactic disks as a consequence of the collision of two spiral galaxies under the influence of a potential which is obtained from the Newtonian limit of a scalar–tensor theory of gravity. We found that dynamical effects depend on parameters (α, λ) of the theory. In particular, we observe that the bar is shorter for weaker tidal perturbations, which in turn corresponds to smaller values of λ used in our numerical experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.2900v1.pdf"}
{"id": "0907.3279", "abstract": "  The power distribution of nearly all major countries have accepted 3-phase distribution as a standard. With increasing power requirements of instrumentation today even a small physics laboratory requires 3-phase supply. While physics students are given an introduction of this in passing, no experiment work is done with 3-phase supply due to the sheer possibility of accidents while working with such large powers. We believe a conceptual understanding of 3-phase supply would be useful for physics students with hands on experience using a simple circuit that can be assembled even in a high school laboratorys. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.3279v1.pdf"}
{"id": "0907.3529", "abstract": "  The transmission rate of many acute infectious diseases varies significantly in time, but the underlying mechanisms are usually uncertain. They may include seasonal changes in the environment, contact rate, immune system response, etc. The transmission rate has been thought difficult to measure directly. We present a new algorithm to compute the time-dependent transmission rate directly from prevalence data, which makes no assumptions about the number of susceptibles or vital rates. The algorithm follows our complete and explicit solution of a mathematical inverse problem for SIR-type transmission models. We prove that almost any infection profile can be perfectly fitted by an SIR model with variable transmission rate. This clearly shows a serious danger of over-fitting such transmission models. We illustrate the algorithm with historic UK measles data and our observations support the common belief that measles transmission was predominantly driven by school contacts. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.3529v4.pdf"}
{"id": "0907.3601", "abstract": "  Theoretical and numerical studies are performed for the nonlinear structures (explosive, solitons and shock) in quantum electron-positron-ion magnetoplasmas. For this purpose, the reductive perturbation method is employed to the quantum hydrodynamical equations and the Poisson equation, obtaining extended quantum Zakharov-Kuznetsov equation. The latter has been solved using the generalized expansion method to obtain a set of analytical solutions, which reflect the possibility of the propagation of various nonlinear structures. The relevance of the present investigation to the white dwarfs is highlighted. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.3601v1.pdf"}
{"id": "0907.3678", "abstract": "  The amplification of the primordial magnetic fields and the gravitational baryogenesis, a mechanism that allows to generate the baryon asymmetry in the Universe by means of the coupling between the Ricci scalar curvature and the baryon current, are reviewed in the framework of the nonlinear electrodynamics. To study the amplification of the primordial magnetic field strength, we write down the gauge invariant wave equations and then solve them (in the long wavelength approximation) for three different eras of the Universe: de Sitter, the reheating and the radiation dominated era. Constraints on parameters entering the nonlinear electrodynamics are obtained by using the amplitude of the observed galactic magnetic fields and the baryon asymmetry, which are characterized by the dimensionless parameters r∼ 10^-37 and η_B≲ 9× 10^-11, respectively. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.3678v1.pdf"}
{"id": "0907.4818", "abstract": "  We introduce a voting model that is similar to a Keynesian beauty contest and analyze it from a mathematical point of view. There are two types of voters-copycat and independent-and two candidates. Our voting model is a binomial distribution (independent voters) doped in a beta binomial distribution (copycat voters). We find that the phase transition in this system is at the upper limit of t, where t is the time (or the number of the votes). Our model contains three phases. If copycats constitute a majority or even half of the total voters, the voting rate converges more slowly than it would in a binomial distribution. If independents constitute the majority of voters, the voting rate converges at the same rate as it would in a binomial distribution. We also study why it is difficult to estimate the conclusion of a Keynesian beauty contest when there is an information cascade. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.4818v2.pdf"}
{"id": "0907.4919", "abstract": "  The wireless medium contains domain-specific information that can be used to complement and enhance traditional security mechanisms. In this paper we propose ways to exploit the spatial variability of the radio channel response in a rich scattering environment, as is typical of indoor environments. Specifically, we describe a physical-layer authentication algorithm that utilizes channel probing and hypothesis testing to determine whether current and prior communication attempts are made by the same transmit terminal. In this way, legitimate users can be reliably authenticated and false users can be reliably detected. We analyze the ability of a receiver to discriminate between transmitters (users) according to their channel frequency responses. This work is based on a generalized channel response with both spatial and temporal variability, and considers correlations among the time, frequency and spatial domains. Simulation results, using the ray-tracing tool WiSE to generate the time-averaged response, verify the efficacy of the approach under realistic channel conditions, as well as its capability to work under unknown channel variations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.4919v1.pdf"}
{"id": "0907.4978", "abstract": "  Blazars are among the most energetic and violent objects in the universe. By observing blazars at very high energies (VHE, E > 100 GeV) we can better understand blazar emission mechanisms, jet structure, black hole accretion and the extragalactic background light (EBL). VERITAS, an array of four 12-meter diameter imaging atmospheric-Cherenkov telescopes, performs VHE studies of blazars through intense monitoring and discovery campaigns. Most blazars known to emit VHE gamma rays are high-frequency-peaked BL Lacertae (HBL) objects, and VERITAS has discovered VHE emission from two of these: 1ES 0806+524 and RGB J0710+591. VERITAS has also discovered VHE gamma rays from two intermediate-frequency-peaked BL Lacertae (IBL) objects: W Com and 3C 66A. The expansion of the VHE catalog to include IBL objects enables a better understanding of the AGN population as a whole. This contribution presents recent results from the VERITAS blazar discovery program. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.4978v1.pdf"}
{"id": "0907.5060", "abstract": "  The ALICE detector has been commissioned and is ready for taking data at the Large Hadron Collider. The first proton-proton collisions are expected in 2009. This contribution describes the current status of the detector, the results of the commissioning phase and its capabilities to contribute to the understanding of both pp and PbPb collisions ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.5060v2.pdf"}
{"id": "0907.5284", "abstract": "  Motivated by Wallace's thesis that pilot wave beables should be decoherence-preferred to recover quantum predictions, we consider the relation between pilot wave beables and decoherence. We prove that without any connection between beables and decoherence the overlap between macrcopic states becomes negligible. This is sufficient to recover quantum predictions, so that Wallace's thesis has to be rejected. A natural connection between decoherence and beables appears if the decomposition into systems used by decoherence is based on the beables. While our first result becomes inapplicable in this case, we present evidence that the overlap becomes negligible too. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.5284v1.pdf"}
{"id": "0907.5459", "abstract": "  The Letter takes up a question of what radio emission is produced by electrons at the very acceleration site of a solar flare. Specifically, we calculate incoherent radio emission produced within two competing acceleration models–stochastic acceleration by cascading MHD turbulence and regular acceleration in collapsing magnetic traps. Our analysis clearly demonstrates that the radio emission from the acceleration sites: (i) has sufficiently strong intensity to be observed by currently available radio instruments and (ii) has spectra and light curves which are distinctly different in these two competing models, which makes them observationally distinguishable. In particular, we suggest that some of the narrowband microwave and decimeter continuum bursts may be a signature of the stochastic acceleration in solar flares. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.5459v1.pdf"}
{"id": "0907.5466", "abstract": "  We have performed near-infrared monitoring observations of Sgr A*, the Galactic center radio source associated with a supermassive black hole, with the near-infrared camera CIAO and the 36-element adaptive optics system on the Subaru telescope. We observed three flares in the Ks band (2.15micron) during 220 min monitoring on 2008 May 28, and confirmed the flare emission is highly polarized, supporting the synchrotron radiation nature of the near-infrared emission. Clear variations in the degree and position angle of polarization were also detected: an increase of the degree of polarization of about 20 ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.5466v2.pdf"}
{"id": "0908.0470", "abstract": "  We discuss a one loop model for neutrino masses which leads to a seesaw-like formula with the difference that the charged lepton masses replace the unknown Dirac mass matrix present in the usual seesaw case. This is a considerable reduction of parameters in the neutrino sector and predicts a strong hierarchical pattern in the right handed neutrino mass matrix that is easily derived from a U(1)_H family symmetry. The model is based on the left-right gauge group with an additional Z_4 discrete symmetry which gives vanishing neutrino Dirac masses and finite Majorana masses arising at the one loop level. Furthermore, it is one of the few models that naturally allow for large (but not necessarily maximal) mixing angles in the lepton sector. A generalization of the model to the quark sector requires three iso-spin singlet vector-like down type quarks, as in E_6. The model predicts an inert doublet type scalar dark matter. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0908/0908.0470v1.pdf"}
{"id": "0908.1953", "abstract": "  We study the nonlinear hopping transport in one-dimensional rings and open channels. Analytical results are derived for the stationary current response to a constant bias without assuming any specific coupling to the external fields. It is shown that anomalous large effective jump lengths, as observed in recent experiments by taking the ratio of the third order nonlinear and the linear conductivity, can occur already in ordered systems. Rectification effects due to site energy disorder in ring systems are expected to become irrelevant for large system sizes. In open channels in contrast, rectification effects occur already for disorder in the jump barriers and do not vanish in the thermodynamic limit. Numerical solutions for a sinusoidal bias show that the ring system provides a good description for the transport behavior in the open channel for intermediate and high frequencies. For low frequencies temporal variations in the mean particle number have to be taken into account in the open channel, which cannot be captured in the more simple ring model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0908/0908.1953v1.pdf"}
{"id": "0908.4596", "abstract": "  We study the resonances of the quantum kicked rotor subjected to an excitation that follows a deterministic time-dependent prescription. For the primary resonances we find an analytical relation between the long-time behavior of the standard deviation and the external kick strength. For the secondary resonances we obtain essentially the same result numerically. Selecting the time sequence of the kick allows to obtain a variety of asymptotic wave-function spreadings: super-ballistic, ballistic, sub-ballistic, diffusive, sub-diffusive and localized. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0908/0908.4596v2.pdf"}
{"id": "0909.0156", "abstract": "  Only some special open surfaces satisfying the shape equation of lipid membranes can be compatible with the boundary conditions. As a result of this compatibility, the first integral of the shape equation should vanish for axisymmetric lipid membranes, from which two theorems of non-existence are verified: (i) There is no axisymmetric open membrane being a part of torus satisfying the shape equation; (ii) There is no axisymmetric open membrane being a part of a biconcave discodal surface satisfying the shape equation. Additionally, the shape equation is reduced to a second-order differential equation while the boundary conditions are reduced to two equations due to this compatibility. Numerical solutions to the reduced shape equation and boundary conditions agree well with the experimental data [A. Saitoh et al., Proc. Natl. Acad. Sci. USA 95, 1026 (1998)]. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.0156v3.pdf"}
{"id": "0909.0545", "abstract": "  In an attempt to understand why catalytic methods for the growth of boron nitride nanotubes work much worse than for their carbon counterparts, we use first-principles calculations to study the energetics of elemental reactions forming N2, B2 and BN molecules on an iron catalyst. We observe that in the case of these small molecules, the catalytic activity is hindered by the formation of B2 on the iron surface. We also observe that the local morphology of a step edge present in our nanoparticle model stabilizes the boron nitride molecule with respect to B2 due to the ability of the step edge to offer sites with different coordination simultaneously for nitrogen and boron. Our results emphasize the importance of atomic steps for a high yield chemical vapor deposition growth of BN nanotubes and may outline new directions for improving the efficiency of the method. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.0545v1.pdf"}
{"id": "0909.4426", "abstract": "  Intraband cyclotron resonance (CR) transitions of a two-electron quantum dot containing a single magnetic ion is investigated for different Coulomb interaction strengths and different positions of the magnetic ion. In contrast to the usual parabolic quantum dots where CR is independent of the number of electrons, we found here that due to the presence of the magnetic ion Kohn's theorem no longer holds and CR is different for systems with different number of electrons and different effective electron-electron Coulomb interaction strength. Many-body effects result in shifts in the transition energies and change the number of CR lines. The position of the magnetic ion inside the quantum dot affects the structure of the CR spectrum by changing the position and the number of crossings and anti-crossings in the transition energies and oscillator strengths. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.4426v1.pdf"}
{"id": "0909.5090", "abstract": "  We investigate theoretically an original route to achieve Bose-Einstein condensation using dark power-law laser traps. We propose to create such traps with two crossing blue-detuned Laguerre-Gaussian optical beams. Controlling their azimuthal order ℓ allows for the exploration of a multitude of power-law trapping situations in one, two and three dimensions, ranging from the usual harmonic trap to an almost square-well potential, in which a quasi-homogeneous Bose gas can be formed. The usual cigar-shaped and disk-shaped Bose-Einstein condensates obtained in a 1D or 2D harmonic trap take the generic form of a \"finger\" or of a \"hockey puck\" in such Laguerre-Gaussian traps. In addition, for a fixed atom number, higher transition temperatures are obtained in such configurations when compared with a harmonic trap of same volume. This effect, which results in a substantial acceleration of the condensation dynamics, requires a better but still reasonable focusing of the Laguerre-Gaussian beams. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.5090v2.pdf"}
{"id": "0910.0195", "abstract": "  We generalize the method of third quantization to a unified exact treatment of Redfield and Lindblad master equations for open quadratic systems of n fermions in terms of diagonalization of 4n x 4n matrix. Non-equilibrium thermal driving in terms of the Redfield equation is analyzed in detail. We explain how to compute all physically relevant quantities, such as non-equilibrium expectation values of local observables, various entropies or information measures, or time evolution and properties of relaxation. We also discuss how to exactly treat explicitly time dependent problems. The general formalism is then applied to study a thermally driven open XY spin 1/2 chain. We find that recently proposed non-equilibrium quantum phase transition in the open XY chain survives the thermal driving within the Redfield model. In particular, the phase of long-range magnetic correlations can be characterized by hypersensitivity of the non-equilibrium-steady state to external (bath or bulk) parameters. Studying the heat transport we find negative thermal conductance for sufficiently strong thermal driving, as well as non-monotonic dependence of the heat current on the strength of the bath coupling. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.0195v1.pdf"}
{"id": "0910.1480", "abstract": "  We present a set of predictions for weak lensing correlation functions in the context of modified gravity models, including a prescription for the impact of the nonlinear power spectrum regime in these models. We consider the DGP and f(R) models, together with dark energy models with the same expansion history. We use the requirement that gravity is close to GR on small scales to estimate the non-linear power for these models. We then calculate weak lensing statistics, showing their behaviour as a function of scale and redshift, and present predictions for measurement accuracy with future lensing surveys, taking into account cosmic variance and galaxy shape noise. We demonstrate the improved discriminatory power of weak lensing for testing modified gravities once the nonlinear power spectrum contribution has been included. We also examine the ability of future lensing surveys to constrain a parameterisation of the non-linear power spectrum, including sensitivity to the growth factor. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.1480v3.pdf"}
{"id": "0910.2644", "abstract": "  The structure of small mixed helium clusters doped with one calcium atom has been determined within the diffusion Monte Carlo framework. The results show that the calcium atom sits at the ^4He-^3He interface. This is in agreement with previous studies, both experimental and theoretical, performed for large clusters. A comparison between the results obtained for the largest cluster we have considered for each isotope shows a clear tendency of the Ca atom to reside in a deep dimple at the surface of the cluster for ^4He clusters, and to become fully solvated for ^3He clusters. We have calculated the absorption spectrum of Ca around the 4s4p ← 4s^2 transition and have found that it is blue-shifted from that of the free-atom transition by an amount that depends on the size and composition of the cluster. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.2644v1.pdf"}
{"id": "0910.3433", "abstract": "  Liquid Argon Time Projection Chamber detectors are ideally suited for studying neutrino interactions and probing the parameters that characterize neutrino oscillations. The ability to drift ionization particles over long distances in purified argon and to trigger on abundant scintillation light allows for excellent particle identification and triggering capability. In these proceedings the details of the ArgoNeuT test-beam project will be presented after a brief introduction to the detector technique. ArgoNeuT is a 175 liter detector exposed to Fermilab's NuMI neutrino beamline. The first neutrino interactions observed in ArgoNeuT will be presented, along with discussion of the various physics analyses to be performed on this data sample. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.3433v1.pdf"}
{"id": "0910.3444", "abstract": "  Conventionally, long GRBs are thought to be caused by the core collapses of massive stars. During the lifetime of a massive star, a stellar wind bubble environment should be produced. Furthermore, the microphysics shock parameters may vary along with the evolution of the fireball. Here we investigate the variation of the microphysics shock parameters under the condition of wind bubble environment, and allow the microphysics shock parameters to be discontinuous at shocks in the ambient medium. It is found that our model can acceptably reproduce the rebrightenings observed in GRB afterglows, at least in some cases. The effects of various model parameters on rebrightenings are investigated. The rebrightenings observed in both the R-band and X-ray afterglow light curves of GRB 060206, GRB 070311 and GRB 071010A are reproduced in this model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.3444v1.pdf"}
{"id": "0910.5547", "abstract": "  We describe an implementation of compressible inviscid fluid solvers with block-structured adaptive mesh refinement on Graphics Processing Units using NVIDIA's CUDA. We show that a class of high resolution shock capturing schemes can be mapped naturally on this architecture. Using the method of lines approach with the second order total variation diminishing Runge-Kutta time integration scheme, piecewise linear reconstruction, and a Harten-Lax-van Leer Riemann solver, we achieve an overall speedup of approximately 10 times faster execution on one graphics card as compared to a single core on the host computer. We attain this speedup in uniform grid runs as well as in problems with deep AMR hierarchies. Our framework can readily be applied to more general systems of conservation laws and extended to higher order shock capturing schemes. This is shown directly by an implementation of a magneto-hydrodynamic solver and comparing its performance to the pure hydrodynamic case. Finally, we also combined our CUDA parallel scheme with MPI to make the code run on GPU clusters. Close to ideal speedup is observed on up to four GPUs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.5547v1.pdf"}
{"id": "0911.0670", "abstract": "  This paper presents a numerical study over a wide parameter space of the likelihood of the dynamical bar-mode instability in differentially rotating magnetized neutron stars. The innovative aspect of this study is the incorporation of magnetic fields in such a context, which have thus far been neglected in the purely hydrodynamical simulations available in the literature. The investigation uses the Cosmos++ code which allows us to perform three dimensional simulations on a cylindrical grid at high resolution. A sample of Newtonian magneto-hydrodynamical simulations starting from a set of models previously analyzed by other authors without magnetic fields has been performed, providing estimates of the effects of magnetic fields on the dynamical bar-mode deformation of rotating neutron stars. Overall, our results suggest that the effect of magnetic fields are not likely to be very significant in realistic configurations. Only in the most extreme cases are the magnetic fields able to suppress growth of the bar mode. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0911/0911.0670v2.pdf"}
{"id": "0911.0870", "abstract": "  Verified and updated calibrated absolute solar flux in the He II 30.4 nm spectral band-pass as measured by the Solar EUV Monitor (SEM) allows us to study variations of the solar EUV irradiance near the minima of Solar Cycles 22/23 and 23/24. Based on eight (1996 to 2007) NASA sounding rocket flights, a comparison of SEM data with the measurements from three independent EUV instruments was performed to verify and confirm the accuracy of the published SEM data. SEM calibrated data were analyzed to determine and compare minima for solar cycles 22/23 and 23/24. The minima points were calculated using SEM first order daily averaged flux smoothed by a running mean (RM) filter with the window of averaging equal to 365 days. These minima occurred on June 2, 1996 (22/23) and November 28, 2008 (23/24). The 23/24 minimum showed about 15", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0911/0911.0870v1.pdf"}
{"id": "0911.3780", "abstract": "  In coupled rotor models which describe identical rotating nuclei the nuclear spin states restrict the possible angular momenta of each molecule. There are two mean-field approaches to determining the orientational phase diagrams in such systems. In one the nuclear spin conversion times are assumed to be instantaneous in the other infinite. In this paper the intermediate case, when the spin conversion times are significantly slower than those of rotational time scales, but are not infinite on the time-scale of the experiment, is investigated. Via incorporation of the configurational degeneracy it is shown that in the thermodynamic limit the mean-field approach in the intermediate case is identical to the instantaneous spin conversion time approximation. The total entropy can be split into configurational and rotational terms. The mean-field phase diagram of a model of coupled rotors of three-fold symmetry is also calculated in the two approximations. It is shown that the configurational entropy has a maximum as a function of temperature which shifts to lower temperatures with increasing order. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0911/0911.3780v2.pdf"}
{"id": "0911.4028", "abstract": "  We examine the density-density correlation function in the Tomonaga-Luttinger liquid state for the one-dimensional extended Hubbard model with the on-site Coulomb repulsion U and the intersite repulsion V at quarter filling. By taking into account the effect of the marginally irrelevant umklapp scattering operator by utilizing the renormalization-group technique based on the bosonization method, we obtain the generalized analytical form of the correlation function. We show that, in the proximity to the gapped charge-ordered phase, the correlation function exhibits anomalous crossover between the pure power-law behavior and the power-law behavior with logarithmic corrections, depending on the length scale. Such a crossover is also confirmed by the highly-accurate numerical density-matrix renormalization group method. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0911/0911.4028v1.pdf"}
{"id": "0911.4803", "abstract": "  The snow line in a gas disk is defined as the distance from the star beyond which the water ice is stable against evaporation. Since oxygen is the most abundant element after hydrogen and helium, the presence of ice grains can have important consequences for disk evolution. However, determining the position of the snow line is not simple. I discuss some of the important processes that affect the position of the snow line. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0911/0911.4803v1.pdf"}
{"id": "0911.4933", "abstract": "  We discuss the photovoltaic effect at a p-n heterojunction, in which the illuminated side is a doped Mott insulator, using the simplest description of a Mott insulator within the Hubbard model. We find that the internal quantum efficiency of such a device, if we choose an appropriate narrow-gap Mott insulator, can be significantly enhanced due to impact ionization caused by the photoexcited “hot” electron/hole pairs. Namely, the photoexcited electron and/or hole can convert its excess energy beyond the Mott-Hubbard gap to additional electrical energy by creating multiple electron/hole pairs in a time scale which can be shorter than the time characterizing other relaxation processes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0911/0911.4933v3.pdf"}
{"id": "0911.5388", "abstract": "  As a classical state, for instance a digitized image, is transferred through a classical channel, it decays inevitably with the distance due to the surroundings' interferences. However, if there are enough number of repeaters, which can both check and recover the state's information continuously, the state's decay rate will be significantly suppressed, then a classical Zeno effect might occur. Such a physical process is purely classical and without any interferences of living beings, therefore, it manifests that the Zeno effect is no longer a patent of quantum mechanics, but does exist in classical stochastic processes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0911/0911.5388v1.pdf"}
{"id": "0912.0989", "abstract": "  We study in this paper the parallel spin current in an antiferromagnetic semiconductor thin film where we take into account the interaction between itinerant spins and lattice spins. The spin model is an anisotropic Heisenberg model. We use here the Boltzmann's equation with numerical data on cluster distribution obtained by Monte Carlo simulations and cluster-construction algorithms. We study the cases of degenerate and non-degenerate semiconductors. The spin resistivity in both cases is shown to depend on the temperature with a broad maximum at the transition temperature of the lattice spin system. The shape of the maximum depends on the spin anisotropy and on the magnetic field. It shows however no sharp peak in contrast to ferromagnetic materials. Our method is applied to MnTe. Comparison to experimental data is given. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0912/0912.0989v4.pdf"}
{"id": "0912.1468", "abstract": "  We study the dynamics of quantum correlations of two coupled double quantum dots containing two excess electrons. The dissipation is included through the contact with an oscillator bath. We solve the Redfield master equation in order to determine the dynamics of the quantum discord and the entanglement of formation. Based on our results, we find that the quantum discord is more resistant to dissipation than the entanglement of formation for such a system. We observe that this characteristic is related to whether the oscillator bath is common to both qubits or not and to the form of the interaction Hamiltonian. Moreover, our results show that the quantum discord might be finite even for higher temperatures in the asymptotic limit. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0912/0912.1468v3.pdf"}
{"id": "0912.1583", "abstract": "  Using our new 3-D relativistic electromagnetic particle (REMP) code parallelized with MPI, we investigated long-term particle acceleration associated with a relativistic electron-positron jet propagating in an unmagnetized ambient electron-positron plasma. We have also performed simulations with electron-ion jets. The simulations were performed using a much longer simulation system than our previous simulations in order to investigate the full nonlinear stage of the Weibel instability for electron-positron jets and its particle acceleration mechanism. Cold jet electrons are thermalized and ambient electrons are accelerated in the resulting shocks for both cases. Acceleration of ambient electrons leads to a maximum ambient electron density three times larger than the original value for pair plasmas. Behind the bow shock in the jet shock strong electromagnetic fields are generated. These fields may lead to time dependent afterglow emission. We calculated radiation from electrons propagating in a uniform parallel magnetic field to verify the technique. We also used the new technique to calculate emission from electrons based on simulations with a small system with two different cases for Lorentz factors (15 and 100). We obtained spectra which are consistent with those generated from electrons propagating in turbulent magnetic fields with red noise. This turbulent magnetic field is similar to the magnetic field generated at an early nonlinear stage of the Weibel instability. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0912/0912.1583v1.pdf"}
{"id": "0912.4175", "abstract": "  We investigate the shear viscosity of neutron star matter in the presence of an antikaon condensate. The electron and muon number densities are reduced due to the appearance of a K^- condensate in neutron star matter, whereas the proton number density increases. Consequently the shear viscosity due to scatterings of electrons and muons with themselves and protons is lowered compared to the case without the condensate. On the other hand, the contribution of proton-proton collisions to the proton shear viscosity through electromagnetic and strong interactions, becomes important and comparable to the neutron shear viscosity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0912/0912.4175v1.pdf"}
{"id": "0912.4343", "abstract": "  The recent analyses of the light curves provided by CoRoT have revealed pulsation spectra of unprecedented richness and precision, in particular, thousands of pulsating modes, and a clear distribution of amplitudes with frequency. In the community, some scientists have started doubting about the validity of the classical tools to analyze these very accurate light curves.   This work provides the asteroseismic community with answers to this question showing that (1) it is physically possible for a star to excite at a time and with the observed amplitudes such a large number of modes; and (2) that the kinetic energy accumulated in all those modes does not destroy the equilibrium of the star. Consequently, mathematical tools presently applied in the analyses of light curves can a priori be trusted. This conclusion is even more important now, when a large amount of space data coming from Kepler are currently being analyzed.   The power spectrum of different stellar cases, and the non-adiabatic code GraCo have been used to estimate the upper limit of the energy per second required to excite all the observed modes, and their total kinetic energy. A necessary previous step for this study is to infer the relative radial pulsational amplitude from the observed photometric amplitude, scaling our linear pulsational solutions to absolute values. The derived upper limits for the required pulsational energy were compared with 1) the luminosity of the star; and 2) the gravitational energy. We obtained that both upper energy limits are orders of magnitude smaller. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0912/0912.4343v1.pdf"}
{"id": "0912.5385", "abstract": "  In a recent series of papers evidence has been presented for correlations between solar activity and nuclear decay rates. This includes an apparent correlation between Earth-Sun distance and data taken at Brookhaven National Laboratory (BNL), and at the Physikalisch-Technische Bundesanstalt (PTB). Although these correlations could arise from a direct interaction between the decaying nuclei and some particles or fields emanating from the Sun, they could also represent an \"environmental\" effect arising from a seasonal variation of the sensitivities of the BNL and PTB detectors due to changes in temperature, relative humidity, background radiation, etc. In this paper, we present a detailed analysis of the responses of the detectors actually used in the BNL and PTB experiments, and show that sensitivities to seasonal variations in the respective detectors are likely too small to produce the observed fluctuations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0912/0912.5385v1.pdf"}
{"id": "1001.4442", "abstract": "  We present a novel approach to derive the age of very young star clusters, by using the Turn-On (TOn). The TOn is the point in the color-magnitude diagram (CMD) where the pre-main sequence (PMS) joins the main sequence (MS). In the MS luminosity function (LF) of the cluster, the TOn is identified as a peak followed by a dip. We propose that by combining the CMD analysis with the monitoring of the spatial distribution of MS stars it is possible to reliably identify the TOn in extragalactic star forming regions. Compared to alternative methods, this technique is complementary to the turn-off dating and avoids the systematic biases affecting the PMS phase. We describe the method and its uncertainties, and apply it to the star forming region NGC346, which has been extensively imaged with the Hubble Space Telescope (HST). This study extends the LF approach in crowded extragalactic regions and opens the way for future studies with HST/WFC3, JWST and from the ground with adaptive optics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1001/1001.4442v1.pdf"}
{"id": "1002.0142", "abstract": "  An effective characterization of chaotic conservative Hamiltonian systems in terms of the curvature associated with a Riemannian metric tensor derived from the structure of the Hamiltonian has been extended to a wide class of potential models of standard form through definition of a conformal metric. The geodesic equations reproduce the Hamilton equations of the original potential model through an inverse map in the tangent space. The second covariant derivative of the geodesic deviation in this space generates a dynamical curvature, resulting in (energy dependent) criteria for unstable behavior different from the usual Lyapunov criteria. We show here that this criterion can be constructively used to modify locally the potential of a chaotic Hamiltonian model in such a way that stable motion is achieved. Since our criterion for instability is local in coordinate space, these results provide a new and minimal method for achieving control of a chaotic system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.0142v1.pdf"}
{"id": "1002.0228", "abstract": "  We present the analysis results of three Gamma-Ray Bursts (GRBs) detected by the Gamma-ray Burst Monitor (GBM) and the Large Area Telescope (LAT) onboard Fermi: the two long GRB 080825C and GRB 090217, and the first short burst with GeV photons GRB 081024B. The emission from GRB 081024B observed by the LAT above 100 MeV is delayed with respect to the GBM trigger, and significantly extends after the low-energy episode. Some hints for spectral hardening was observed in this burst as well as in GRB 080825C, possibly related to a separate and harder component showing up at late times. Conversely, GRB 090217 does not exhibit any noticeable feature. Together with the other bright LAT detected bursts (e.g. GRB 080916C and GRB 090510), these observations help to classify the GRB properties and give new insight on the acceleration mechanisms responsible for their emission at the highest energies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.0228v1.pdf"}
{"id": "1002.0436", "abstract": "  We study how to protect quantum information in quantum systems subjected to local dissipation. We show that combining the use of three-level systems, environment monitoring, and local feedback can fully and deterministically protect any available quantum information, including entanglement initially shared by different parties. These results can represent a gain in resources and/or distances in quantum communication protocols such as quantum repeaters and teleportation as well as time for quantum memories. Finally, we show that monitoring local environments physically implements the optimum singlet conversion protocol, essential for classical entanglement percolation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.0436v2.pdf"}
{"id": "1002.0636", "abstract": "  We identified a large sample of radio quasars, including those with complex radio morphology, from the Sloan Digital Sky Survey (SDSS) and the Faint Images of Radio Sky at Twenty-cm (FIRST). Using this sample, we inspect previous radio quasar samples for selection effects resulting from complex radio morphologies and adopting positional coincidence between radio and optical sources alone. We find that 13.0", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.0636v2.pdf"}
{"id": "1002.1693", "abstract": "  The input to the configuration-interaction shell model includes many dozens or hundreds of independent two-body matrix elements. Previous studies have shown that when fitting to experimental low-lying spectra, the greatest sensitivity is to only a few linear combinations of matrix elements. Here we consider interactions drawn from the two-body random ensemble, or TBRE, and find that the low-lying spectra are also most sensitive to only a few linear combinations of two-body matrix elements, in a fashion nearly indistinguishable from an interaction empirically fit to data. We find in particular the spectra for both the random and empirical interactions are sensitive to similar matrix elements, which we analyze using monopole and contact interactions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.1693v1.pdf"}
{"id": "1002.2272", "abstract": "  The middle-aged supernova remnant (SNR) W51C is an interesting source for the interaction of the shell with a molecular cloud. The shell emits intense radio synchrotron photons, and high-energy gamma-rays from the remnant have been detected using the Fermi Large Area Telescope (LAT), the H.E.S.S. telescope, and the Milagro gamma-ray observatory. Based on a semi-analytical approach to the nonlinear shock acceleration process, we investigate the multiband nonthermal emission from W51C. The result shows that the radio emission from the remnant can be explained as synchrotron radiation of the electrons accelerated by a part of the shock flowing into the ambient medium. On the other hand, the high-energy gamma-rays detected by the Fermi LAT are mainly produced via proton-proton collisions of the high-energy protons with the ambient matter in the molecular cloud overtaken by the other part of the shock. We propose a possible explanation of the multiband nonthermal emission from W51C, and it can be concluded that a molecular cloud overtaken by a shock wave can be an important emitter in GeV γ-rays. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.2272v1.pdf"}
{"id": "1002.2411", "abstract": "  The availability of continuous helioseismic data for two consecutive solar minima has provided a unique opportunity to study the changes in the solar interior that might have led to this unusual minimum. We present preliminary analysis of inter mediate-degree mode frequencies in the 3 mHz band during the current period of minimal solar activity and show that the mode frequencies are significantly lower than those during the previous activity minimum. Our analysis do not show any signature of the beginning of cycle 24 till the end of 2008. In addition, the zonal and meridional flow patterns inferred from inverting frequencies also hint for a delayed onset of a new cycle. The estimates of travel time are higher than the previous minimum confirming a relatively weak solar activity during the current minimum. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.2411v1.pdf"}
{"id": "1002.2448", "abstract": "  We study dynamics of a ball moving in gravitational field and colliding with a moving table. The motion of the limiter is assumed as periodic with piecewise constant velocity - it is assumed that the table moves up with a constant velocity and then moves down with another constant velocity. The Poincare map, describing evolution from an impact to the next impact, is derived and scenarios of transition to chaotic dynamics are investigated analytically. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.2448v1.pdf"}
{"id": "1002.4437", "abstract": "  We consider a cavity optomechanical system consisting of a Bose-Einstein condensate (BEC) interacting with two counterpropagating traveling-wave modes in an optical ring cavity. In contrast to the more familiar case where the condensate is driven by the standing-wave field of a high-Q Fabry-Pérot cavity we find that both symmetric and antisymmetric collective density side modes of the BEC are mechanically excited by the light field. In the semiclassical, mean-field limit where the light field and the zero-momentum mode of the condensate are treated classically the system is found to exhibit a rich multistable behavior, including the appearance of isolated branches of solutions (isolas). We also present examples of the dynamics of the system as input parameters such as the frequency of the driving lasers are varied. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1002/1002.4437v1.pdf"}
{"id": "1003.0365", "abstract": "  We present an ab-initio and analytical study of the Jahn-Teller effect in two diluted magnetic semiconductors (DMS) with d4 impurities, namely Mn-doped GaN and Cr-doped ZnS. We show that only the combined treatment of Jahn-Teller distortion and strong electron correlation in the 3d shell may lead to the correct insulating electronic structure. Using the LSDA+U approach we obtain the Jahn-Teller energy gain in reasonable agreement with the available experimental data. The ab-initio results are completed by a more phenomenological ligand field theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.0365v1.pdf"}
{"id": "1003.0582", "abstract": "  We study the dynamical correlation functions of the Richardson pairing model (also known as the reduced or discrete-state BCS model) in the canonical ensemble. We use the Algebraic Bethe Ansatz formalism, which gives exact expressions for the form factors of the most important observables. By summing these form factors over a relevant set of states, we obtain very precise estimates of the correlation functions, as confirmed by global sum-rules (saturation above 99", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.0582v1.pdf"}
{"id": "1003.1193", "abstract": "  A diversity of resonance configurations may be formed under different migration of two giant planets. And the researchers show that the HD 128311 and HD 73526 planetary systems are involved in a 2:1 mean motion resonance but not in apsidal corotation, because one of the resonance argument circulates over the dynamical evolution. In this paper, we investigate potential mechanisms to form the 2:1 librating-circulating resonance configuration.   In the late stage of planetary formation, scattering or colliding among planetesimals and planetary embryos can frequently occur. Hence, in our model, we consider a planetary configuration of two giants together with few terrestrial planets. We find that both colliding or scattering events at very early stage of dynamical evolution can influence the configurations trapped into resonance. A planet-planet scattering of a moderate terrestrial planet, or multiple scattering of smaller planets in a crowded planetary system can change the resonant configuration. In addition, collision or merging can alter the masses and location of the giant planets, which also play an important role in shaping the resonant configuration during the dynamical evolution. In this sense, the librating-circulating resonance configuration is more likely to form by a hybrid mechanism of scattering and collision. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.1193v1.pdf"}
{"id": "1003.1310", "abstract": "  We present a study of the scaling properties of cluster-cluster aggregation with a source of monomers in the stationary state when the spatial transport of particles occurs by Levy flights. We show that the transition from mean-field statistics to fluctuation-dominated statistics which, for the more commonly considered case of diffusive transport, occurs as the spatial dimension of the system is tuned through two from above, can be mimicked even in one dimension by varying the characteristic exponent, beta, of the the Levy jump length distribution. We also show that the two-point mass correlation function, responsible for the flux of mass in the stationary state, is strongly universal: its scaling exponent is given by the mean field value independent of the spatial dimension and independent of the value of beta. Finally we study numerically the two point spatial correlation function which characterises the structure of the depletion zone around heavy particles in the diffusion limited regime. We find that this correlation function vanishes with a non-trivial fractional power of the separation between particles as this separation goes to zero. We provide a scaling argument for the value of this exponent which is in reasonable agreement with the numerical measurements. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.1310v2.pdf"}
{"id": "1003.4277", "abstract": "  It is well known that the rock-paper-scissors game has no pure saddle point. We show that this holds more generally: A symmetric two-player zero-sum game has a pure saddle point if and only if it is not a generalized rock-paper-scissors game. Moreover, we show that every finite symmetric quasiconcave two-player zero-sum game has a pure saddle point. Further sufficient conditions for existence are provided. We apply our theory to a rich collection of examples by noting that the class of symmetric two-player zero-sum games coincides with the class of relative payoff games associated with symmetric two-player games. This allows us to derive results on the existence of a finite population evolutionary stable strategies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.4277v1.pdf"}
{"id": "1003.5034", "abstract": "  We suggest a possible explanation for the high frequency quasi-periodic oscillations (QPOs) in black hole low mass X-ray binaries. By solving the perturbation general relativistic magnetohydrodynamic equations, we find two stable modes of the Alfv́en wave in the the accretion disks with toroidal magnetic fields. We suggest that these two modes may lead to the double high frequency QPOs if they are produced in the transition region between the inner advection dominated accretion flow and the outer thin disk. This model naturally accounts for the 3 : 2 relation for the upper and lower frequencies of the QPOs, and the relation between the black hole mass and QPO frequency. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.5034v1.pdf"}
{"id": "1003.5242", "abstract": "  It is shown that temperature acts to disrupt the magnetization of Peierls distorted quasi-one-dimensional materials (Q1DM). The mean-field finite temperature phase diagram for the field theory model employed is obtained by considering both homogeneous and inhomogeneous condensates. The tricritical points of the second order transition lines of the gap parameter and magnetization are explicitly calculated. It is also shown that in the absence of an external static magnetic field the magnetization is always zero, at any temperature. As expected, temperature does not induce any magnetization effect on Peierls distorted Q1DM. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.5242v1.pdf"}
{"id": "1003.5614", "abstract": "  The classical dynamical model for reactions induced by weakly-bound nuclei at near-barrier energies is developed further. It allows a quantitative study of the role and importance of incomplete fusion dynamics in asymptotic observables, such as the population of high-spin states in reaction products as well as the angular distribution of direct alpha-production. Model calculations indicate that incomplete fusion is an effective mechanism for populating high-spin states, and its contribution to the direct alpha production yield diminishes with decreasing energy towards the Coulomb barrier. It also becomes notably separated in angles from the contribution of no-capture breakup events. This should facilitate the experimental disentanglement of these competing reaction processes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.5614v1.pdf"}
{"id": "1003.5858", "abstract": "  We investigate the dynamical formation of crystalline states with systems of polar molecules or Rydberg atoms loaded into a deep optical lattice. External fields in these systems can be used to couple the atoms or molecules between two internal states: one that is weakly interacting and one that exhibits a strong dipole-dipole interaction. By appropriate time variation of the external fields, we show that it is possible to produce crystalline states of the strongly interacting states with high filling fractions chosen via the parameters of the coupling. We study the coherent dynamics of this process in one dimension (1D) using a modified form of the time-evolving block decimation (TEBD) algorithm, and obtain crystalline states for system sizes and parameters corresponding to realistic experimental configurations. For polar molecules these crystalline states will be long-lived, assisting in a characterization of the state via the measurement of correlation functions. We also show that as the coupling strength increases in the model, the crystalline order is broken. This is characterized in 1D by a change in density-density correlation functions, which decay to a constant in the crystalline regime, but show different regions of exponential and algebraic decay for larger coupling strengths. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1003/1003.5858v2.pdf"}
{"id": "1004.0277", "abstract": "  Mesoscopic molecular dynamics simulations are used to determine the large scale structure of several binary polymer mixtures of various chemical architecture, concentration, and thermodynamic conditions. By implementing an analytical formalism, which is based on the solution to the Ornstein-Zernike equation, each polymer chain is mapped onto the level of a single soft colloid. From the appropriate closure relation, the effective, soft-core potential between coarse-grained units is obtained and used as input to our mesoscale simulations. The potential derived in this manner is analytical and explicitly parameter dependent, making it general and transferable to numerous systems of interest. From computer simulations performed under various thermodynamic conditions the structure of the polymer mixture, through pair correlation functions, is determined over the entire miscible region of the phase diagram. In the athermal regime mesoscale simulations exhibit quantitative agreement with united atom simulations. Furthermore, they also provide information at larger scales than can be attained by united atom simulations and in the thermal regime approaching the phase transition. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.0277v1.pdf"}
{"id": "1004.0968", "abstract": "  Electrostatic velocity filtering is a technique for the production of continuous guided beams of slow polar molecules from a thermal gas. We extended this technique to produce pulses of slow molecules with a narrow velocity distribution around a tunable velocity. The pulses are generated by sequentially switching the voltages on adjacent segments of an electric quadrupole guide synchronously with the molecules propagating at the desired velocity. This technique is demonstrated for deuterated ammonia (ND_3), delivering pulses with a velocity in the range of 20-100 m/s and a relative velocity spread of (16± 2)", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.0968v2.pdf"}
{"id": "1004.1955", "abstract": "  We consider the problem of communicating over a multiple-input multiple-output (MIMO) real valued channel for which no mathematical model is specified, and achievable rates are given as a function of the channel input and output sequences known a-posteriori. This paper extends previous results regarding individual channels by presenting a rate function for the MIMO individual channel, and showing its achievability in a fixed transmission rate communication scenario. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.1955v2.pdf"}
{"id": "1004.2147", "abstract": "  In the framework of the Tsallis nonextensive statistical mechanics we study an assembly of N spins, first in a background magnetic field, and then assuming them to interact via a long-range homogeneous mean field. To take into account the spin fluctuations the dynamical field coefficient is considered to be linearly dependent on the temperature. The physical quantities are evaluated using a perturbative expansion in the nonextensivity parameter (1-q). The extended Curie-Weiss law in the mean field case has been generalized. The critical temperature and the Curie- Weiss constant are found to be dependent on the nonextensivity parameter (1-q). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.2147v2.pdf"}
{"id": "1004.2561", "abstract": "  Noneqiuilibrium dynamics of rotating droplets are studied by molecular dynamics simulations. Small deviations from the theoretical prediction are observed when the size of a droplet is small, and the deviations become smaller as the size of the droplet increases. The characteristic timescale of the deformation is observed, and we find (i) the deformation timescale is almost independent of the rotating velocity with for small frequency and (ii) the deformation timescale becomes shorter as temperature increases. A simple model is proposed to explain the deformation dynamics of droplets. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.2561v2.pdf"}
{"id": "1004.2589", "abstract": "  We discuss how to prepare an Ising chain in a GHZ state using a single global control field only. This model does not require the spins to be individually addressable and is applicable to quantum systems such as cold atoms in optical lattices, some liquid- or solid-state NMR experiments, and many nano-scale quantum structures. We show that GHZ states can always be reached asymptotically from certain easy-to-prepare initial states using adiabatic passage, and under certain conditions finite-time reachability can be ensured. To provide a reference useful for future experimental implementations three different control strategies to achieve the objective, adiabatic passage, Lyapunov control and optimal control are compared, and their advantages and disadvantages discussed, in particular in the presence of realistic imperfections such as imperfect initial state preparation, system inhomogeneity and dephasing. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.2589v2.pdf"}
{"id": "1004.4606", "abstract": "  The electrical conductivity of graphene containing point defects is studied within the binary alloy model in its dependence on the Fermi level position at the zero temperature. It is found that the minimal conductivity value does not have a universal character and corresponds to the impurity resonance energy rather than to the Dirac point position in the spectrum. The substantial asymmetry of the resulting dependence of the conductivity on the gate voltage magnitude is attributed as well to this same shift of the conductivity minimum to the resonance state energy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.4606v2.pdf"}
{"id": "1004.5020", "abstract": "  The dynamic behavior of a multiagent system in which the agent size s_i is variable it is studied along a Lotka-Volterra approach. The agent size has hereby for meaning the fraction of a given market that an agent is able to capture (market share). A Lotka-Volterra system of equations for prey-predator problems is considered, the competition factor being related to the difference in size between the agents in a one-on-one competition. This mechanism introduces a natural self-organized dynamic competition among agents. In the competition factor, a parameter σ is introduced for scaling the intensity of agent size similarity, which varies in each iteration cycle. The fixed points of this system are analytically found and their stability analyzed for small systems (with n=5 agents). We have found that different scenarios are possible, from chaotic to non-chaotic motion with cluster formation as function of the σ parameter and depending on the initial conditions imposed to the system. The present contribution aim is to show how a realistic though minimalist nonlinear dynamics model can be used to describe market competition (companies, brokers, decision makers) among other opinion maker communities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.5020v1.pdf"}
{"id": "1004.5415", "abstract": "  We present a set of low resolution empirical SED templates for AGNs and galaxies in the wavelength range from 0.03 to 30 microns. These templates form a non-negative basis of the color space of such objects and have been derived from a combination 14448 galaxies and 5347 likely AGNs in the NDWFS Bootes field. We briefly describe how the templates are derived and discuss some applications of them. In particular, we discuss biases in commonly used AGN mid-IR color selection criteria and the expected distribution of sources in the current WISE satellite mission. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1004/1004.5415v1.pdf"}
{"id": "1005.2865", "abstract": "  Quantum decoherence, which appears when a system interacts with its environment in an irreversible way, plays a fundamental role in the description of quantum-to-classical transitions and has been successfully applied in some important experiments. Here, we study the decoherence in noninertial frames for the first time. It is shown that the decoherence and loss of the entanglement generated by the Unruh effect will influence each other remarkably. It is interesting to note that in the case of the total system under decoherence, the sudden death of entanglement may appear for any acceleration. However, in the case of only Rob's qubit underging decoherence sudden death may only occur when the acceleration parameter is greater than a \"critical point.\" ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1005/1005.2865v4.pdf"}
{"id": "1005.4626", "abstract": "  In the general MSSM, first and second generation squarks and gluinos may be sufficiently light to be produced and studied at e^+e^- colliders operating in the 0.5-1 TeV energy range. After a reminder that the MSSM is not the same as mSUGRA, we provide a brief overview of these possibilities within this more general framework ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1005/1005.4626v1.pdf"}
{"id": "1006.0387", "abstract": "  We solve the relativistic Riemann problem in viscous matter using the relativistic Boltzmann equation and the relativistic causal dissipative fluid-dynamical approach of Israel and Stewart. Comparisons between these two approaches clarify and point out the regime of validity of second-order fluid dynamics in relativistic shock phenomena. The transition from ideal to viscous shocks is demonstrated by varying the shear viscosity to entropy density ratio η/s. We also find that a good agreement between these two approaches requires a Knudsen number Kn < 1/2. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1006/1006.0387v3.pdf"}
{"id": "1006.1274", "abstract": "  Kerr geometry has twofoldedness which can be cured by a truncation of the `negative' sheet of metric. It leads to the models of disk-like sources of the Kerr solution and to a class of disk-like or bag-like models of the Kerr spinning particle. There is an alternative way: to retain the `negative' sheet as the sheet of advanced fields. In this case the source of spinning particle is the Kerr singular ring which can be considered as a twofold \"Alice\" string. This string can have electromagnetic excitations in the form of traveling waves generating spin and mass of the particle. Model of this sort was suggested in 1974 as a \"microgeon with spin\". Recent progress in the obtaining of the nonstationary and radiating Kerr solutions enforces us to return to this model and to consider it as a model for the light spinning particles. We discuss here the real and complex Kerr geometry and some unusual properties of the oscillating solutions in the model of \"Alice\" string source. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1006/1006.1274v1.pdf"}
{"id": "1006.3032", "abstract": "  The I3322 inequality is the simplest bipartite two-outcome Bell inequality beyond the Clauser-Horne-Shimony-Holt (CHSH) inequality, consisting of three two-outcome measurements per party. In case of the CHSH inequality the maximal quantum violation can already be attained with local two-dimensional quantum systems, however, there is no such evidence for the I3322 inequality. In this paper a family of measurement operators and states is given which enables us to attain the largest possible quantum value in an infinite dimensional Hilbert space. Further, it is conjectured that our construction is optimal in the sense that measuring finite dimensional quantum systems is not enough to achieve the true quantum maximum. We also describe an efficient iterative algorithm for computing quantum maximum of an arbitrary two-outcome Bell inequality in any given Hilbert space dimension. This algorithm played a key role to obtain our results for the I3322 inequality, and we also applied it to improve on our previous results concerning the maximum quantum violation of several bipartite two-outcome Bell inequalities with up to five settings per party. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1006/1006.3032v1.pdf"}
{"id": "1006.3599", "abstract": "  In Japan, China and Russia, there are several test beam lines available or will become available in near future. Those are open for users who need electron, muon and charged pion beams with energies of 1-50 GeV for any tests of small-size detectors. In this manuscript I present a current status of those test beam facilities in the Asian region. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1006/1006.3599v1.pdf"}
{"id": "1006.3894", "abstract": "  Hahn and Wallsten wrote that network neutrality \"usually means that broadband service providers charge consumers only once for Internet access, do not favor one content provider over another, and do not charge content providers for sending information over broadband lines to end users.\" In this paper we study the implications of non-neutral behaviors under a simple model of linear demand-response to usage-based prices. We take into account advertising revenues and consider both cooperative and non-cooperative scenarios. In particular, we model the impact of side-payments between service and content providers. We also consider the effect of service discrimination by access providers, as well as an extension of our model to non-monopolistic content providers. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1006/1006.3894v1.pdf"}
{"id": "1006.5418", "abstract": "  In this paper we study the cosmological constant emerging from the Wheeler-DeWitt equation as an eigenvalue of the related Sturm-Liouville problem. We employ Gaussian trial functionals and we perform a mode decomposition to extract the transverse-traceless component, namely, the graviton contribution, at one loop. We implement a noncommutative-geometry- induced minimal length to calculate the number of graviton modes. As a result, we find regular graviton fluctuation energies for the Schwarzschild, de Sitter, and anti-de Sitter backgrounds. No renormalization scheme is necessary to remove infinities, in contrast to what happens in conventional approaches. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1006/1006.5418v2.pdf"}
{"id": "1007.0144", "abstract": "  This paper investigates design of noncooperative games from an optimization and control theoretic perspective. Pricing mechanisms are used as a design tool to ensure that the Nash equilibrium of a fairly general class of noncooperative games satisfies certain global objectives such as welfare maximization or achieving a certain level of quality-of-service (QoS). The class of games considered provide a theoretical basis for decentralized resource allocation and control problems including network congestion control, wireless uplink power control, and optical power control. The game design problem is analyzed under different knowledge assumptions (full versus limited information) and design objectives (QoS versus utility maximization) for separable and non-separable utility functions. The “price of anarchy” is shown not to be an inherent feature of full-information games that incorporate pricing mechanisms. Moreover, a simple linear pricing is shown to be sufficient for design of Nash equilibrium according to a chosen global objective for a fairly general class of games. Stability properties of the game and pricing dynamics are studied under the assumption of time-scale separation and in two separate time-scales. Thus, sufficient conditions are derived, which allow the designer to place the Nash equilibrium solution or to guide the system trajectory to a desired region or point. The obtained results are illustrated with a number of examples. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1007/1007.0144v1.pdf"}
{"id": "1007.2475", "abstract": "  We consider Einstein gravity coupled to an U(1) gauge field for which the density is given by a power of the Maxwell Lagrangian. In d-dimensions the action of Maxwell field is shown to enjoy the conformal invariance if the power is chosen as d/4. We present a class of charge rotating solutions in Einstein-conformally invariant Maxwell gravity in the presence of a cosmological constant. These solutions may be interpreted as black brane solutions with inner and outer event horizons or an extreme black brane depending on the value of the mass parameter. Since we are considering power of the Maxwell density, the black brane solutions exist only for dimensions which are multiples of four. We compute conserved and thermodynamics quantities of the black brane solutions and show that the expression of the electric field does not depend on the dimension. Also, we obtain a Smarr-type formula and show that these conserved and thermodynamic quantities of black branes satisfy the first law of thermodynamics. Finally, we study the phase behavior of the rotating black branes and show that there is no Hawking–Page phase transition in spite of conformally invariant Maxwell field. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1007/1007.2475v1.pdf"}
{"id": "1007.2712", "abstract": "  We have developed a Multi-Pixel Photon Counter (MPPC) for the neutrino detectors of T2K experiment. About 64,000 MPPCs have been produced and tested in about a year. In order to characterize a large number of MPPCs, we have developed a system that simultaneously measures 64 MPPCs with various bias voltage and temperature. The performance of MPPCs are found to satisfy the requirement of T2K experiment. In this paper, we present the performance of 17,686 MPPCs measured at Kyoto University. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1007/1007.2712v1.pdf"}
{"id": "1008.0081", "abstract": "  The Polyakov-extended quark-meson model (PQM) is investigated beyond mean-field. This represents an important step towards a fully dynamical QCD computation. Both the quantum fluctuations to the matter sector and the back-reaction of the matter fluctuations to the QCD Yang-Mills sector are included. Results on the chiral and confinement-deconfinement crossover/phase transition lines and the location of a possible critical endpoint are presented. Moreover, thermodynamic quantities such as the pressure and the quark density are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1008/1008.0081v1.pdf"}
{"id": "1008.0431", "abstract": "  Posttranslational modification of proteins is key in transmission of signals in cells. Many signaling pathways contain several layers of modification cycles that mediate and change the signal through the pathway. Here, we study a simple signaling cascade consisting of n layers of modification cycles, such that the modified protein of one layer acts as modifier in the next layer. Assuming mass-action kinetics and taking the formation of intermediate complexes into account, we show that the steady states are solutions to a polynomial in one variable, and in fact that there is exactly one steady state for any given total amounts of substrates and enzymes.   We demonstrate that many steady state concentrations are related through rational functions, which can be found recursively. For example, stimulus-response curves arise as inverse functions to explicit rational functions. We show that the stimulus-response curves of the modified substrates are shifted to the left as we move down the cascade. Further, our approach allows us to study enzyme competition, sequestration and how the steady state changes in response to changes in the total amount of substrates.   Our approach is essentially algebraic and follows recent trends in the study of posttranslational modification systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1008/1008.0431v2.pdf"}
{"id": "1008.3556", "abstract": "  We study the dynamic electronic polarizability of a single nano-scale spherical metallic grain using quantum mechanical approach. We introduce the model for interacting electrons bound in the grain allowing us numerically to calculate the frequency dependence of the polarizability of grains of different sizes. We show that within this model the main resonance peak corresponding to the surface plasmon mode is blue-shifted and some minor secondary resonances above and below the main peak exist. We study the behavior of blue shift as a function of grain size and compare our findings with the classical polarizability and with other results in the literature. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1008/1008.3556v2.pdf"}
{"id": "1008.3924", "abstract": "  We investigate the global chirality distribution of the quantum walk on the line when decoherence is introduced either through simultaneous measurements of the chirality and particle position, or as a result of broken links. The first mechanism drives the system towards a classical diffusive behavior. This is used to build new quantum games, similar to the spin-flip game. The second mechanism involves two different possibilities: (a) All the quantum walk links have the same probability of being broken. (b) Only the quantum walk links on a half-line are affected by random breakage. In case (a) the decoherence drives the system to a classical Markov process, whose master equation is equivalent to the dynamical equation of the quantum density matrix. This is not the case in (b) where the asymptotic global chirality distribution unexpectedly maintains some dependence with the initial condition. Explicit analytical equations are obtained for all cases. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1008/1008.3924v1.pdf"}
{"id": "1008.4866", "abstract": "  We estimate the amount of vorticity generated at second order in cosmological perturbation theory from the coupling between first order energy density and non-adiabatic pressure, or entropy, perturbations. Assuming power law input spectra for the source terms, and working in a radiation background, we calculate the wave number dependence of the vorticity power spectrum and its amplitude. We show that the vorticity generated by this mechanism is non-negligible on small scales, and hence should be taken into consideration in current and future CMB experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1008/1008.4866v2.pdf"}
{"id": "1008.5050", "abstract": "  The high frequency component in blazars is thought to be due to inverse Compton scattered radiation. Recent observations by Fermi-LAT are used to evaluate the details of the scattering process. A comparison is made between the usually assumed single scattering scenario and one in which multiple scatterings are energetically important. In the latter case, most of the radiation is emitted in the Klein-Nishina limit. It is argued that several of the observed correlations defining the blazar sequence are most easily understood in a multiple scattering scenario. Observations indicate also that, in such a scenario, the blazar sequence is primarily governed by the energy density of relativistic electrons rather than that of the seed photons. The pronounced X-ray minimum in the spectral energy distribution often observed in the most luminous blazars is discussed. It is shown how this feature can be accounted for in a multiple scattering scenario by an extension of standard one-zone models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1008/1008.5050v1.pdf"}
{"id": "1008.5324", "abstract": "  We propose to search for neutron halo isomers populated via γ-capture in stable nuclei with mass numbers of about A=140-180 or A=40-60, where the 4s_1/2 or 3s_1/2 neutron shell model state reaches zero binding energy. These halo nuclei can be produced for the first time with new γ-beams of high intensity and small band width (≤ 0.1", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1008/1008.5324v2.pdf"}
{"id": "1008.5398", "abstract": "  We analyze electron transport data through a Si/SiGe double quantum dot in terms of spin blockade and lifetime-enhanced transport (LET), which is transport through excited states that is enabled by long spin relaxation times. We present a series of low-bias voltage measurements showing the sudden appearance of a strong tail of current that we argue is an unambiguous signature of LET appearing when the bias voltage becomes greater than the singlet-triplet splitting for the (2,0) electron state. We present eight independent data sets, four in the forward bias (spin-blockade) regime and four in the reverse bias (lifetime-enhanced transport) regime, and show that all eight data sets can be fit to one consistent set of parameters. We also perform a detailed analysis of the reverse bias (LET) regime, using transport rate equations that include both singlet and triplet transport channels. The model also includes the energy dependent tunneling of electrons across the quantum barriers, and resonant and inelastic tunneling effects. In this way, we obtain excellent fits to the experimental data, and we obtain quantitative estimates for the tunneling rates and transport currents throughout the reverse bias regime. We provide a physical understanding of the different blockade regimes and present detailed predictions for the conditions under which LET may be observed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1008/1008.5398v2.pdf"}
{"id": "1009.1276", "abstract": "  Dynamics of flexible ferromagnetic filaments in an external magnetic field is considered. We report the existence of a buckling instability of the ferromagnetic filament at the magnetic field reversion, which leads to the formation of a metastable loop. Its relaxation through three dimensional transformation of the configurations is observed experimentally and confirmed by numerical simulations. Bending modulus of the flexible ferromagnetic filaments synthesized by linking micron size core-shell ferromagnetic particles with DNA fragments is estimated by comparison of the parameters of the loops observed in the experiment with theoretical calculations. Formation of the loop and its relaxation are characterized by the numerically calculated writhe number. The relaxation time of the loop allows us to estimate the hydrodynamic drag of the filament. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.1276v1.pdf"}
{"id": "1009.2317", "abstract": "  We experimentally demonstrate the storage of 1060 temporal modes onto a thulium-doped crystal using an atomic frequency comb (AFC). The comb covers 0.93 GHz defining the storage bandwidth. As compared to previous AFC preparation methods (pulse sequences i.e. amplitude modulation), we only use frequency modulation to produce the desired optical pumping spectrum. To ensure an accurate spectrally selective optical pumping, the frequency modulated laser is self-locked on the atomic comb. Our approach is general and should be applicable to a wide range of rare-earth doped material in the context of multimode quantum memory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.2317v2.pdf"}
{"id": "1009.2867", "abstract": "  High-dimensional quantum states, or qudits, represent a promising resource in the quantum information field. Here we present the experimental generation of four-dimensional quantum states, or ququarts, encoded in the polarization and orbital angular momentum of a single photon. Our novel technique, based on the q-plate device, allows to prepare and measure the ququart in all five mutually unbiased bases. We report the reconstruction of the four dimensional density matrix through the tomographic procedure for different ququart states. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.2867v1.pdf"}
{"id": "1009.4074", "abstract": "  I review the good, the bad and the ugly of the non-projectable versions of Horava gravity. I explain how this non-relativistic theory was constructed and why it was touted with such excitement as a quantum theory of gravity. I then review some of the issues facing the theory, explaining how strong coupling occurs and why this is such a problem for both phenomenology and the question of renormalisability. Finally I comment on possible violations of Equivalence Principle, and explain why these could be an issue for Blas et al's \"healthy extension\". This paper was presented as a talk at PASCOS 2010 in Valencia. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.4074v1.pdf"}
{"id": "1009.4335", "abstract": "  We update a physically-motivated model of radiation damage in the Hubble Space Telescope Advanced Camera for Surveys/Wide Field Channel, using data up to mid 2010. We find that Charge Transfer Inefficiency increased dramatically before shuttle Servicing Mission 4, with  1.3 charge traps now present per pixel. During detector readout, charge traps spuriously drag electrons behind all astronomical sources, degrading image quality in a way that affects object photometry, astrometry and morphology. Our detector readout model is robust to changes in operating temperature and background level, and can be used to iteratively remove the trailing by pushing electrons back to where they belong. The result is data taken in mid-2010 that recovers the quality of imaging obtained within the first six months of orbital operations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.4335v1.pdf"}
{"id": "1009.6071", "abstract": "  We present a complete systematically theoretical study of multifragmentation for asymmetric colliding nuclei for heavy-ion reactions in the energy range between 50 MeV/nucleon and 600 MeV/nucleon by using soft and hard equations of state. This study is performed within an isospindependent quantum molecular dynamics model. To see the effect of mass asymmetry, simulations are carried out in the absence of Coulomb interactions. Coulomb interactions enhances the production of fragments by about 20", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.6071v1.pdf"}
{"id": "1010.0047", "abstract": "  The Prisoner's Dilemma is a simple model that captures the essential contradiction between individual rationality and global rationality. Although the one-shot Prisoner's Dilemma is usually viewed simple, in this paper we will categorize it into five different types. For the type-4 Prisoner's Dilemma game, we will propose a self-enforcing algorithmic model to help non-cooperative agents obtain Pareto-efficient payoffs. The algorithmic model is based on an algorithm using complex numbers and can work in macro applications. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.0047v5.pdf"}
{"id": "1010.0854", "abstract": "  We analyze the impact of the sampling interval on the estimation of Kramers-Moyal coefficients. We obtain the finite-time expressions of these coefficients for several standard processes. We also analyze extreme situations such as the independence and no-fluctuation limits that constitute useful references. Our results aim at aiding the proper extraction of information in data-driven analysis. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.0854v2.pdf"}
{"id": "1010.1295", "abstract": "  We consider the optimal packet scheduling problem in a single-user energy harvesting wireless communication system. In this system, both the data packets and the harvested energy are modeled to arrive at the source node randomly. Our goal is to adaptively change the transmission rate according to the traffic load and available energy, such that the time by which all packets are delivered is minimized. Under a deterministic system setting, we assume that the energy harvesting times and harvested energy amounts are known before the transmission starts. For the data traffic arrivals, we consider two different scenarios. In the first scenario, we assume that all bits have arrived and are ready at the transmitter before the transmission starts. In the second scenario, we consider the case where packets arrive during the transmissions, with known arrival times and sizes. We develop optimal off-line scheduling policies which minimize the time by which all packets are delivered to the destination, under causality constraints on both data and energy arrivals. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.1295v1.pdf"}
{"id": "1010.1598", "abstract": "  In this paper we present an extension of the Recent Fluid Deformation (RFD) closure introduced by Chevillard and Meneveau (2006) which was developed for modeling the time evolution of Lagrangian fluctuations in incompressible Navier-Stokes turbulence. We apply the RFD closure to study the evolution of magnetic and passive scalar fluctuations. This comparison is especially interesting since the stretching term for the magnetic field and for the gradient of the passive scalar are similar but differ by a sign such that the effect of stretching and compression by the turbulent velocity field is reversed. Probability density functions (PDFs) of magnetic fluctuations and fluctuations of the gradient of the passive scalar obtained from the RFD closure are compared against PDFs obtained from direct numerical simulations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.1598v2.pdf"}
{"id": "1010.1916", "abstract": "  We present a new construction related to systems of polynomials which are consistent on a cube. The consistent polynomials underlie the integrability of discrete counterparts of integrable partial differential equations of Korteweg- de Vries-type (KdV-type). The construction reported here associates a Schwarzian variable to such systems. In the generic case, including the primary model Q4, the new variable satisfies the lattice Schwarzian Kadomtsev-Petviashvili (KP) equat ion in three dimensions. For the degenerate sub-cases of Q4 the same construction reveals an invertible transformation to the lattice Schwarzian KdV equation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.1916v1.pdf"}
{"id": "1010.2502", "abstract": "  We develop a technique to investigate the possibility that some of the recently discovered ultra-faint dwarf satellites of the Milky Way might be cusp caustics rather than gravitationally self-bound systems. Such cusps can form when a stream of stars folds, creating a region where the projected 2-D surface density is enhanced. In this work, we construct a Poisson maximum likelihood test to compare the cusp and exponential models of any substructure on an equal footing. We apply the test to the Hercules dwarf (d   113 kpc, M_V   -6.2, e   0.67). The flattened exponential model is strongly favored over the cusp model in the case of Hercules, ruling out at high confidence that Hercules is a cusp catastrophe. This test can be applied to any of the Milky Way dwarfs, and more generally to the entire stellar halo population, to search for the cusp catastrophes that might be expected in an accreted stellar halo. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.2502v2.pdf"}
{"id": "1010.3387", "abstract": "  We use a combination of VJHK and Spitzer [3.6], [5.8] and [8.0] photometry, to determine IR excesses in a sample of LMC and SMC O stars. This sample is ideal for determining excesses because: 1) the distances to the stars, and hence their luminosities, are well-determined, and; 2) the very small line of sight reddenings minimize the uncertainties introduced by extinction corrections. We find IR excesses much larger than expected from Vink et al. (2001) mass loss rates. This is in contrast to previous wind line analyses for many of the LMC stars which suggest mass loss rates much less than the Vink et al. predictions. ogether, these results indicate that the winds of the LMC and SMC O stars are strongly structured (clumped). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.3387v1.pdf"}
{"id": "1010.3702", "abstract": "  We characterize the infall rate onto protostellar systems forming in self-gravitating radiation-hydrodynamic simulations. Using two dimensionless parameters to determine disks' susceptability to gravitational fragmentation, we infer limits on protostellar system multiplicity and the mechanism of binary formation. We show that these parameters give robust predictions even in the case of marginally resolved protostellar disks. We find that protostellar systems with radiation feedback predominately form binaries via turbulent fragmentation, not disk instability, and we predict turbulent fragmentation is the dominant channel for binary formation for low-mass stars. We clearly demonstrate that systems forming in simulations including radiative feedback have fundamentally different parameters than those in purely hydrodynamic simulations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.3702v1.pdf"}
{"id": "1010.3937", "abstract": "  Extensive Monte Carlo simulations were carried out to investigate the nature of the ordering transition of a model of adsorbed self-assembled rigid rods on the bonds of a square lattice [Tavares et. al., Phys. Rev E 79, 021505 (2009)]. The polydisperse rods undergo a continuous ordering transition that is found to be in the two-dimensional Ising universality class, as in models where the rods are monodisperse. This finding is in sharp contrast with the recent claim that equilibrium polydispersity changes the nature of the phase transition in this class of models [L`opez et. al., Phys. Rev E 80, 040105(R)(2009)]. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.3937v1.pdf"}
{"id": "1010.4176", "abstract": "  Bright single and binary stars were observed at the 4.1-m telescope with a fast electron-multiplication camera in the regime of partial turbulence correction by the visible-light adaptive optics system. We compare the angular resolution achieved by simple averaging of AO-corrected images (long-exposure), selection and re-centering (shift-and-add or \"lucky\" imaging) and speckle interferometry. The effect of partial AO correction, vibrations, and image post-processing on the attained resolution is shown. Potential usefulness of these techniques is evaluated for reaching the diffraction limit in ground-based optical imaging. Measurements of 75 binary stars obtained during these tests are given and objects of special interest are discussed. We report tentative resolution of the astrometric companion to Zeta Aqr B. A concept of advanced high-resolution camera is outlined. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.4176v1.pdf"}
{"id": "1010.4385", "abstract": "  In this work we present a protocol for self-synchronized duty-cycling in wireless sensor networks with energy harvesting capabilities. The protocol is implemented in Wiselib, a library of generic algorithms for sensor networks. Simulations are conducted with the sensor network simulator Shawn. They are based on the specifications of real hardware known as iSense sensor nodes. The experimental results show that the proposed mechanism is able to adapt to changing energy availabilities. Moreover, it is shown that the system is very robust against packet loss. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.4385v1.pdf"}
{"id": "1010.4629", "abstract": "  Genome-Wide Association Studies (GWAS) offer an exciting and promising new research avenue for finding genes for complex diseases. Traditional case-control and cohort studies offer many advantages for such designs. Family-based association designs have long been attractive for their robustness properties, but robustness can mean a loss of power. In this paper we discuss some of the special features of family designs and their relevance in the era of GWAS. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.4629v1.pdf"}
{"id": "1010.5666", "abstract": "  Using a real-time renormalization group method we study the minimal model of a quantum dot dominated by charge fluctuations, the two-lead interacting resonant level model, at finite bias voltage. We develop a set of RG equations to treat the case of weak and strong charge fluctuations, together with the determination of power-law exponents up to second order in the Coulomb interaction. We derive analytic expressions for the charge susceptibility, the steady-state current and the conductance in the situation of arbitrary system parameters, in particular away from the particle-hole symmetric point and for asymmetric Coulomb interactions. In the generic asymmetric situation we find that power laws can be observed for the current only as function of the level position (gate voltage) but not as function of the voltage. Furthermore, we study the quench dynamics after a sudden switch-on of the level-lead couplings. The time evolution of the dot occupation and current is governed by exponential relaxation accompanied by voltage-dependent oscillations and characteristic algebraic decay. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.5666v4.pdf"}
{"id": "1010.5905", "abstract": "  Massive stars disproportionately influence their surroundings. How they form has only started to become clear recently through radiation gas dynamical simulations. However, until now, no simulation has simultaneously included both magnetic fields and ionizing radiation. Here we present the results from the first radiation-magnetohydrodynamical (RMHD) simulation including ionization feedback, comparing an RMHD model of a 1000 M_sol rotating cloud to earlier radiation gas dynamical models with the same initial density and velocity distributions. We find that despite starting with a strongly supercritical mass to flux ratio, the magnetic field has three effects. First, the field offers locally support against gravitational collapse in the accretion flow, substantially reducing the amount of secondary fragmentation in comparison to the gas dynamical case. Second, the field drains angular momentum from the collapsing gas, further increasing the amount of material available for accretion by the central, massive, protostar, and thus increasing its final mass by about 50", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.5905v2.pdf"}
{"id": "1011.0106", "abstract": "  Using scanning gate microscopy (SGM), we probe the scattering between a beam of electrons and a two-dimensional electron gas (2DEG) as a function of the beam's injection energy, and distance from the injection point. At low injection energies, we find electrons in the beam scatter by small-angles, as has been previously observed. At high injection energies, we find a surprising result: placing the SGM tip where it back-scatters electrons increases the differential conductance through the system. This effect is explained by a non-equilibrium distribution of electrons in a localized region of 2DEG near the injection point. Our data indicate that the spatial extent of this highly non-equilibrium distribution is within  1 micrometer of the injection point. We approximate the non-equilibrium region as having an effective temperature that depends linearly upon injection energy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1011/1011.0106v1.pdf"}
{"id": "1011.2543", "abstract": "  Predicting nonequilibrium fluctuations requires a knowledge of nonequilibrium distribution functions. Despite the distributions' fractal character some theoretical results, \"Fluctuation Theorems\", reminiscent of but distinct from, Gibbs' equilibrium statistical mechanics and the Central Limit Theorem, have been established away from equilibrium and applied to simple models. We summarize the simplest of these results for a Gaussian-thermostated Galton Board problem, a field-driven mass point moving through a periodic array of hard-disk scatterers. The billion-collision trillion-timestep data we analyze correspond to periodic orbits with up to 793,951,594 collisions and 447,064,397,614 timesteps. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1011/1011.2543v3.pdf"}
{"id": "1011.4021", "abstract": "  We show how interpenetrating optical lattices containing Bose-Fermi mixtures can be constructed to emulate the thermodynamics of quantum electrodynamics (QED). We present models of neutral atoms on lattices in 1+1, 2+1 and 3+1 dimensions whose low energy effective action reduces to that of photons coupled to Dirac fermions of the corresponding dimensionality. We give special attention to 2+1 dimensional electrodynamics (QED3) and discuss how two of its most interesting features, chiral symmetry breaking and Chern-Simons physics, could be observed experimentally. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1011/1011.4021v1.pdf"}
{"id": "1011.5376", "abstract": "  We re-examine the question of whether the geometrical ground state of neutral and ionized clusters are identical. Using a well defined criterion for being \"identical\" together, the extensive sampling methods on a potential energy surface calculated by density functional theory, we show that the ground states are in general different. This behavior is to be expected whenever there are metastable configurations which are close in energy to the ground state, but it disagrees with previous studies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1011/1011.5376v2.pdf"}
{"id": "1011.5612", "abstract": "  Assuming that the final state of hadronization takes place along the freezeout line, which is defined by a constant entropy density, the antiproton-to-proton ratios produced in heavy-ion collisions are studied in framework of the hadron resonance gas (HRG) model. A phase transition from quark–gluon plasma to hadrons, a hadronization, has been conjectured in order to allow modifications in the phase space volume and thus in single–particle distribution function. Implementing both modifications in the grand–canonical partition function and taking into account the experimental acceptance in heavy-ion collisions, the antiproton-to-proton ratios over center-of-mass energies √(s) ranging from AGS to RHIC are very well reproduced by the HRG model. Comparing with the same particle ratios in pp collisions results in a gradually narrowing discrepancy with increasing √(s). At LHC energy, the ALICE antiproton-to-proton ratios in pp collisions turn to be very well described by HRG model as well. It is likely that the ALICE heavy-ion program will produce the same antiproton-to-proton ratios as the pp program. Furthermore, the ratio gets very close to unity indicating that the matter-antimatter asymmetry nearly vanishes. The chemical potential calculated at this energy strengthens the assumption of almost fully matter-antimatter symmetry at LHC energy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1011/1011.5612v1.pdf"}
{"id": "1012.0720", "abstract": "  It is shown that the magnetic current-driven (`kink-type') instability produces flow and field patterns with helicity and even with α-effect but only if the magnetic background field possesses non-vanishing current helicity B̅⃗̅·curl B̅⃗̅ by itself. Fields with positive large-scale current helicity lead to negative small-scale kinetic helicity. The resulting α-effect is positive. These results are very strict for cylindric setups without <i>z/I>-dependence of the background fields. The sign rules also hold for the more complicated cases in spheres where the toroidal fields are the result of the action of differential rotation (induced from fossil poloidal fields) at least for the case that the global rotation is switched off after the onset of the instability. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.0720v1.pdf"}
{"id": "1012.0790", "abstract": "  Integrated optic beam combiners offer many advantages over conventional bulk optic implementations for astronomical imaging. To date, integrated optic beam combiners have only been demonstrated at operating wavelengths below 4 microns. Operation in mid-infrared wavelength region, however, is highly desirable. In this paper, a theoretical design technique based on three coupled waveguides is developed to achieve fully achromatic, broadband, polarization-insensitive, lossless beam combining. This design may make it possible to achieve the very deep broadband nulls needed for exoplanet searching. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.0790v1.pdf"}
{"id": "1012.1584", "abstract": "  We present results of two-hour non-interrupted observations of solar granulation obtained under excellent seeing conditions with the largest aperture ground-based solar telescope - the New Solar Telescope (NST) - of Big Bear Solar Observatory. Observations were performed with adaptive optics correction using a broad-band TiO filter in the 705.7 nm spectral line with a time cadence of 10 s and a pixel size of 0.0375\". Photospheric bright points (BPs) were detected and tracked. We find that the BPs detected in NST images are co-spatial with those visible in Hinode/SOT G-band images. In cases where Hinode/SOT detects one large BP, NST detects several separated BPs. Extended filigree features are clearly fragmented into separate BPs in NST images. The distribution function of BP sizes extends to the diffraction limit of NST (77 km) without saturation and corresponds to a log-normal distribution. The lifetime distribution function follows a log-normal approximation for all BPs with lifetime exceeding 100 s. A majority of BPs are transient events reflecting the strong dynamics of the quiet sun: 98.6", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.1584v1.pdf"}
{"id": "1012.4080", "abstract": "  Bearing in mind the application to the outer crust of the neutron stars (NSs), we investigate the magnetic field decay by means of the fully relativistic Particle-In-Cell simulations. Numerical computations are carried out in 2-dimensions, in which the initial magnetic fields are set to be composed both of the uniform magnetic fields that model the global fields penetrating the NS and of the turbulent magnetic fields that would be originated from the Hall cascade of the large-scale turbulence. Our results show that the whistler cascade of the turbulence transports the magnetic energy preferentially in the direction perpendicular to the uniform magnetic fields. It is also found that the distribution function of electrons becomes anisotropic because electrons with lower energies are predominantly heated in the direction parallel to the uniform magnetic fields due to the Landau resonance, while electrons with higher energies are heated mainly by the cyclotron resonance that makes the distribution function isotropic for the high energy tails. Furthermore we point out that the degree of anisotropy takes maximum as a function of the initial turbulent magnetic energy. As an alternative to the conventional ohmic dissipation, we propose that the magnetic fields in the outer crust of NSs, cascading down to the electron inertial scale via the whistler turbulence, would decay predominantly by the dissipation processes through the Landau damping and the cyclotron resonance. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.4080v1.pdf"}
{"id": "1012.4238", "abstract": "  A new class of inflation models within the context of G-inflation is proposed, in which the standard model Higgs boson can act as an inflaton thanks to Galileon-like non-linear derivative interaction. The generated primordial density perturbation is shown to be consistent with the present observational data. We also make a general discussion on potential-driven G-inflation models, and find a new consistency relation between the tensor-to-scalar ratio r and the tensor spectral index n_T, r = -32 √(6)n_T / 9, which is crucial in discriminating the present models from standard inflation with a canonical kinetic term. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.4238v1.pdf"}
{"id": "1012.4345", "abstract": "  Quantum spin Hall insulator/metal interfaces are formed in graphene ribbons with intrinsic spin-orbit coupling by selectively doping two regions creating a potential step. For a clean graphene ribbon, the transmission of the topological edge states through a n-n or p-p junction is perfect irrespective of the ribbon termination, width, and potential step parameters due to the orthogonality of incoming and outgoing edge channels. This is shown numerically for an arbitrary crystallographic orientation of the ribbon and proven analytically for zigzag and metallic armchair boundary conditions. In disordered ribbons, the orthogonality between left- and right-movers is in general destroyed and backscattering sets in. However, transmission approaches one by increasing the ribbon's width, even in the presence of strong edge roughness. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.4345v3.pdf"}
{"id": "1101.2542", "abstract": "  Charge carriers in graphene are chiral quasiparticles (\"massless Dirac fermions\"). Graphene provides therefore an amazing opportunity to study subtle quantum relativistic effects in condensed matter experiment. Here I review a theory of one of these unusual features of graphene, a \"pseudodiffusive\" transport in the limit of zero charge carrier concentration, which is related to existence of zero-modes of the Dirac operator and to the Zitterbewegung of unltrarelativistic particles. A conformal mapping technique is a powerful mathematical tool to study these phenomena, as demonstrated here, using the Aharonov-Bohm effect in graphene rings with Corbino geometry as an example. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1101/1101.2542v1.pdf"}
{"id": "1101.3240", "abstract": "  We investigate the validity of the generalized second law of gravitational thermodynamics on the apparent and event horizons in a non-flat FRW universe containing the interacting dark energy with dark matter. We show that for the dynamical apparent horizon, the generalized second law is always satisfied throughout the history of the universe for any spatial curvature and it is independent of the equation of state parameter of the interacting dark energy model. Whereas for the cosmological event horizon, the validity of the generalized second law depends on the equation of state parameter of the model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1101/1101.3240v1.pdf"}
{"id": "1101.3976", "abstract": "  The fractal shape and multi-component nature of the interstellar medium together with its vast range of dynamical scales provides one of the great challenges in theoretical and numerical astrophysics. Here we will review recent progress in the direct modelling of interstellar hydromagnetic turbulence, focusing on the role of energy injection by supernova explosions. The implications for dynamo theory will be discussed in the context of the mean-field approach. Results obtained with the test field-method are confronted with analytical predictions and estimates from quasilinear theory. The simulation results enforce the classical understanding of a turbulent Galactic dynamo and, more importantly, yield new quantitative insights. The derived scaling relations enable confident global mean-field modelling. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1101/1101.3976v1.pdf"}
{"id": "1101.4519", "abstract": "  The Wang-Silk approximation, 1/Q   1/Q_stars + 1/Q_gas, is frequently used for estimating the effective Q parameter in two-component discs of stars and gas. Here we analyse this approximation in detail, and show how its accuracy depends on the radial velocity dispersions and Toomre parameters of the two components. We then propose a much more accurate but still simple approximation for the effective Q parameter, which further takes into account the stabilizing effect of disc thickness. Our effective Q parameter is a natural generalization of Toomre's Q, and as such can be used in a wide variety of contexts, e.g. for predicting star formation thresholds in galaxies or for measuring the stability level of galactic discs at low and high redshifts. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1101/1101.4519v3.pdf"}
{"id": "1101.5408", "abstract": "  Coincident observations with gravitational wave (GW) detectors and other astronomical instruments are in the focus of the experiments with the network of LIGO, Virgo and GEO detectors. They will become a necessary part of the future GW astronomy as the next generation of advanced detectors comes online. The success of such joint observations directly depends on the source localization capabilities of the GW detectors. In this paper we present studies of the sky localization of transient sources with the future advanced detector networks and describe their fundamental properties. By reconstructing sky coordinates of ad hoc signals injected into simulated detector noise we study the accuracy of the source localization and its dependence on the strength of injected signals, waveforms and network configurations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1101/1101.5408v1.pdf"}
{"id": "1101.5465", "abstract": "  We propose the Kolmogorov stochasticity parameter, λ for energy level spectra to classify quantum systems with corresponding classical dynamics ranging from integrable to chaotic. We also study the probability distribution function (PDF) of λ. Remarkably, the PDF of all the integrable systems studied here is the same and is found to be completely different from the PDF of chaotic systems. We also note that λ_n for n energy levels scales as λ_n ∼ n^-α. Furthermore, with α, the stochastic probability (calculated from PDF) is seen to jump by about an order of magnitude as the systems turn chaotic. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1101/1101.5465v1.pdf"}
{"id": "1101.5780", "abstract": "  In the present work the dynamics of a continuous inextensible chain is studied. The chain is regarded as a system of small particles subjected to constraints on their reciprocal distances. It is proposed a treatment of systems of this kind based on a set Langevin equations in which the noise is characterized by a non-gaussian probability distribution. The method is explained in the case of a freely hinged chain. In particular, the generating functional of the correlation functions of the relevant degrees of freedom which describe the conformations of this chain is derived. It is shown that in the continuous limit this generating functional coincides with a model of an inextensible chain previously discussed by one of the authors of this work. Next, the approach developed here is applied to a inextensible chain, called the freely jointed bar chain, in which the basic units are small extended objects. The generating functional of the freely jointed bar chain is constructed. It is shown that it differs profoundly from that of the freely hinged chain. Despite the differences, it is verified that in the continuous limit both generating functionals coincide as it is expected. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1101/1101.5780v2.pdf"}
{"id": "1101.6037", "abstract": "  A Monte Carlo algorithm is said to be adaptive if it automatically calibrates its current proposal distribution using past simulations. The choice of the parametric family that defines the set of proposal distributions is critical for good performance. In this paper, we present such a parametric family for adaptive sampling on high-dimensional binary spaces. A practical motivation for this problem is variable selection in a linear regression context. We want to sample from a Bayesian posterior distribution on the model space using an appropriate version of Sequential Monte Carlo. Raw versions of Sequential Monte Carlo are easily implemented using binary vectors with independent components. For high-dimensional problems, however, these simple proposals do not yield satisfactory results. The key to an efficient adaptive algorithm are binary parametric families which take correlations into account, analogously to the multivariate normal distribution on continuous spaces. We provide a review of models for binary data and make one of them work in the context of Sequential Monte Carlo sampling. Computational studies on real life data with about a hundred covariates suggest that, on difficult instances, our Sequential Monte Carlo approach clearly outperforms standard techniques based on Markov chain exploration. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1101/1101.6037v4.pdf"}
{"id": "1102.0376", "abstract": "  Distribution of the two phonon γ vibrational collectivity in the rotating triaxial odd-A nucleus, ^103Nb, that is one of the three nuclides for which experimental data were reported recently, is calculated in the framework of the particle vibration coupling model based on the cranked shell model plus random phase approximation. This framework was previously utilized for analyses of the zero and one phonon bands in other mass region and is applied to the two phonon band for the first time. In the present calculation, three sequences of two phonon bands share collectivity almost equally at finite rotation whereas the K=Ω+4 state is the purest at zero rotation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.0376v3.pdf"}
{"id": "1102.0661", "abstract": "  Results of VLBI and GPS observations were analyzed with goal to investigate differences in observed baseline length derived from both techniques. VLBI coordinates for European stations were obtained from processing of all available observations collected on European and global VLBI network. Advanced model for antenna thermal deformation was applied to account for change of horizontal component of baseline length. GPS data were obtained from re-processing of the weekly EPN (European Permanent GPS Network) solutions. Systematic differences between results obtained with two techniques including linear drift and seasonal effects are determined. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.0661v1.pdf"}
{"id": "1102.0795", "abstract": "  We present spectroscopic observations confirming the identification of hot white dwarfs among UV-bright sources from the Sandage Two-color Survey of the Galactic plane and listed in the Lanning (Lan) catalog of such sources. A subsample of 213 UV bright Lan sources have been identified as candidate white dwarfs based on the detection of a significant proper motion. Spectroscopic observations of 46 candidates with the KPNO 2.1m telescope confirm 30 sources to be hydrogen white dwarfs with subtypes in the DA1-DA6 range, and with one of the stars (Lan 161) having an unresolved M dwarf as a companion. Five more sources are confirmed to be helium white dwarfs, with subtypes from DB3 to DB6. One source (Lan 364) is identified as a DZ 3 white dwarf, with strong lines of calcium. Three more stars are found to have featureless spectra (to within detection limits), and are thus classified as DC white dwarfs. In addition, three sources are found to be hot subdwarfs: Lan 20 and Lan 480 are classified as sdOB, and Lan 432 is classified sdB. The remaining four objects are found to be field F star interlopers. Physical parameters of the DA and DB white dwarfs are derived from model fits. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.0795v1.pdf"}
{"id": "1102.3474", "abstract": "  The Belinskii, Khalatnikov and Lifshitz conjecture <cit.> posits that on approach to a space-like singularity in general relativity the dynamics are well approximated by `ignoring spatial derivatives in favor of time derivatives.' In <cit.> we examined this idea from within a Hamiltonian framework and provided a new formulation of the conjecture in terms of variables well suited to loop quantum gravity. We now present the details of the analytical part of that investigation. While our motivation came from quantum considerations, thanks to some of its new features, our formulation should be useful also for future analytical and numerical investigations within general relativity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.3474v2.pdf"}
{"id": "1102.3625", "abstract": "  As a test-bed for future investigations of directly imaged terrestrial exoplanets, we present the recovery of the surface components of the Earth from multi-band diurnal light curves obtained with the EPOXI spacecraft. We find that the presence and longitudinal distribution of ocean, soil and vegetation are reasonably well reproduced by fitting the observed color variations with a simplified model composed of a priori known albedo spectra of ocean, soil, vegetation, snow and clouds. The effect of atmosphere, including clouds, on light scattered from surface components is modeled using a radiative transfer code. The required noise levels for future observations of exoplanets are also determined. Our model-dependent approach allows us to infer the presence of major elements of the planet (in the case of the Earth, clouds and ocean) with observations having S/N ≳ 10 in most cases and with high confidence if S/N ≳ 20. In addition, S/N ≳ 100 enables us to detect the presence of components other than ocean and clouds in a fairly model-independent way. Degradation of our inversion procedure produced by cloud cover is also quantified. While cloud cover significantly dilutes the magnitude of color variations compared to the cloudless case, the pattern of color changes remains. Therefore, the possibility of investigating surface features through light curve fitting remains even for exoplanets with cloud cover similar to the Earth's. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.3625v3.pdf"}
{"id": "1102.3713", "abstract": "  Inhomogeneity, in its many forms, appears frequently in practical physical systems. Readily apparent in quantum systems, inhomogeneity is caused by hardware imperfections, measurement inaccuracies, and environmental variations, and subsequently limits the performance and efficiency achievable in current experiments. In this paper, we provide a systematic methodology to mathematically characterize and optimally manipulate inhomogeneous ensembles with concepts taken from ensemble control. In particular, we develop a computational method to solve practical quantum pulse design problems cast as optimal ensemble control problems, based on multidimensional pseudospectral approximations. We motivate the utility of this method by designing pulses for both standard and novel applications. We also show the convergence of the pseudospectral method for optimal ensemble control. The concepts developed here are applicable beyond quantum control, such as to neuron systems, and furthermore to systems with by parameter uncertainty, which pervade all areas of science and engineering. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.3713v1.pdf"}
{"id": "1102.4603", "abstract": "  Hadronic interaction models at cosmic ray (CR) energies are inherently uncertain due to the lack of a fundamental theoretical description of soft hadronic and nuclear interactions and the large extrapolation required from collider energies to the range of the most energetic cosmic rays observed (>10^20 eV). Model uncertainties are evaluated within the QGSJET-II model, by varying some of the crucial parameters in the limits allowed by collider data, and between QGSJET-II and other models commonly used in air shower simulations. The crucial parameters relate to hard processes, string fragmentation, diffraction and baryon production. Results on inelastic cross sections, on secondary particle production and on the properties of air showers measured by ground detectors from energies of 10^12 to 10^19 eV are presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.4603v2.pdf"}
{"id": "1102.5303", "abstract": "  We study the structural properties of a quasi-one-dimensional classical Wigner crystal, confined in the transverse direction by a parabolic potential. With increasing density, the one-dimensional crystal first splits into a zigzag crystal before progressively more rows appear. While up to four rows the ground state possesses a regular structure, five-row crystals exhibit defects in a certain density regime. We identify two phases with different types of defects. Furthermore, using a simplified model, we show that beyond nine rows no stable regular structures exist. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.5303v1.pdf"}
{"id": "1102.5702", "abstract": "  The question if the Bose statistics is broken at the TeV scale is discussed. The decay of a new heavy spin 1 gauge boson Z' into two photons, Z'-> 2 gamma, is forbidden by the Bose statistics among other general principles of quantum field theory (Landau-Yang theorem). We point out that the search for this decay can be effectively used to probe the Bose symmetry violation at the CERN LHC. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.5702v2.pdf"}
{"id": "1103.0695", "abstract": "  We present a list of galaxies within 100 Mpc, which we call the Gravitational Wave Galaxy Catalogue (GWGC), that is currently being used in follow-up searches of electromagnetic counterparts from gravitational wave searches. Due to the time constraints of rapid follow-up, a locally available catalogue of reduced, homogenized data is required. To achieve this we used four existing catalogues: an updated version of the Tully Nearby Galaxy Catalog, the Catalog of Neighboring Galaxies, the V8k catalogue and HyperLEDA. The GWGC contains information on sky position, distance, blue magnitude, major and minor diameters, position angle, and galaxy type for 53,255 galaxies. Errors on these quantities are either taken directly from the literature or estimated based on our understanding of the uncertainties associated with the measurement method. By using the PGC numbering system developed for HyperLEDA, the catalogue has a reduced level of degeneracies compared to catalogues with a similar purpose and is easily updated. We also include 150 Milky Way globular clusters. Finally, we compare the GWGC to previously used catalogues, and find the GWGC to be more complete within 100 Mpc due to our use of more up-to-date input catalogues and the fact that we have not made a blue luminosity cut. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.0695v1.pdf"}
{"id": "1103.0815", "abstract": "  We consider effective interactions in a 2D hybrid polariton- electron system and calculate dispersion of elementary excitations accounting the spin degree of freedom of the particles. Due to the crucial role played by the exchange term in polariton- electron interactions the dispersions of this system become spin- dependent and show unusual behavior. The coupling of the excitations of the condensate with 2D plasmon can result in appearence of roton minimum in the dispersion and destruction of the condensate for close enough situated quantum wells with electrons and excitons. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.0815v1.pdf"}
{"id": "1103.1024", "abstract": "  It is argued that antiparticles may be interpreted in macroscopic terms without explicitly using the concept of time and its reversal. The appropriate framework is that of nonrelativistic phase space. It is recalled that a quantum version of this approach leads also, alongside the appearance of antiparticles, to the emergence of `internal' quantum numbers identifiable with weak isospin, weak hypercharge and colour, and to the derivation of the Gell-Mann-Nishijima relation, while simultaneously offering a preonless interpretation of the Harari-Shupe rishon model. Furthermore, it is shown that - under the assumption of the additivity of canonical momenta - the approach entails the emergence of string-like structures resembling mesons and baryons, thus providing a different starting point for the discussion of quark unobservability. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.1024v1.pdf"}
{"id": "1103.2416", "abstract": "  We consider a cosmology in which the final stage of the Universe is neither accelerating nor decelerating, but approaches an asymptotic state where the scale factor becomes a constant value. In order to achieve this, we first bring in a scale factor with the desired property and then determine the details of the energy contents as a result of the cosmological evolution equations. We show that such a scenario can be realized if we introduce a generalized quintom model which consists of a scalar field and a phantom with a negative cosmological constant term. The standard cold dark matter with w_m=0 is also introduced. This is possible basically due to the balance between the matter and the negative cosmological constant which tend to attract and scalar field and phantom which repel in the asymptotic region. The stability analysis shows that this asymptotic solution is classically stable. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.2416v3.pdf"}
{"id": "1103.2699", "abstract": "  We report theoretical calculations on the effect of the multiple orbital contribution in high-order harmonic generation (HHG) from aligned CO_2 with inclusion of macroscopic propagation of harmonic fields in the medium. Our results show very good agreements with recent experiments for the dynamics of the minimum in HHG spectra as laser intensity or alignment angle changes. Calculations are carried out to check how the position of the minimum in HHG spectra depends on the degrees of molecular alignment, laser focusing conditions, and the effects of alignment-dependent ionization rates of the different molecular orbitals. These analyses help to explain why the minima observed in different experiments may vary. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.2699v1.pdf"}
{"id": "1103.5131", "abstract": "  This paper studies n-person simultaneous-move games with linear best response function, where individuals interact within a given network structure. This class of games have been used to model various settings, such as, public goods, belief formation, peer effects, and oligopoly. The purpose of this paper is to study the effect of the network structure on Nash equilibrium outcomes of this class of games. Bramoullé et al. derived conditions for uniqueness and stability of a Nash equilibrium in terms of the smallest eigenvalue of the adjacency matrix representing the network of interactions. Motivated by this result, we study how local structural properties of the network of interactions affect this eigenvalue, influencing game equilibria. In particular, we use algebraic graph theory and convex optimization to derive new bounds on the smallest eigenvalue in terms of the distribution of degrees, cycles, and other relevant substructures. We illustrate our results with numerical simulations involving online social networks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.5131v2.pdf"}
{"id": "1104.0503", "abstract": "  We consider the dynamics of charge carriers in single-layer graphene that are subject to random temporal fluctuations of their mass gap. The optical conductivity is calculated by incorporating the quantum-stochastic time evolution into the standard linear-response (Kubo) theory. We find that, for an intermediate range of frequencies below the average gap size, electron transport is enhanced by fluctuations. At the same time, in the limit of high as well as low frequencies, the conductivity is suppressed as the variance of gap fluctuations increases. In particular, the dc conductivity is always suppressed by a random temporal mass with nonvanishing mean value and vanishes in the zero-temperature limit. Our results are complementary to those obtained recently for static random-gap disorder in finite-size systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1104/1104.0503v2.pdf"}
{"id": "1104.0633", "abstract": "  In this work, we establish the bulk superconductivity of a high quality sample of monoclinic BiPd (α-BiPd, space group P2_1) below 3.87 K by studying its electrical resistivity, magnetic susceptibility and heat capacity. We show that it is clean type-II superconductor with moderate electron-phonon coupling and determine its superconducitng and normal state parameters. Although α-BiPd is a noncentrosymmetric superconductor with large electronic heat capacity (therefore, large γ), the effect of spin-orbit splitting of the electronic bands at the Fermi level is small. This makes little influence on the superconducting properties of α-BiPd. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1104/1104.0633v1.pdf"}
{"id": "1104.1065", "abstract": "  The changes of dynamical behaviour of a single fullerene molecule inside an armchair carbon nanotube caused by the structural Peierls transition in the nanotube are considered. The structures of the smallest C20 and Fe@C20 fullerenes are computed using the spin-polarized density functional theory. Significant changes of the barriers for motion along the nanotube axis and rotation of these fullerenes inside the (8,8) nanotube are found at the Peierls transition. It is shown that the coefficients of translational and rotational diffusions of these fullerenes inside the nanotube change by several orders of magnitude. The possibility of inverse orientational melting, i.e. with a decrease of temperature, for the systems under consideration is predicted. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1104/1104.1065v2.pdf"}
{"id": "1104.3496", "abstract": "  We study the constraints on the Lee-Wick Higgs sector arising from direct collider searches. We work in an effective-field theory framework, where all of the Lee-Wick partners are integrated out, with the sole exception of the Lee-Wick Higgs bosons. The resulting theory is a two-Higgs doublet model where the second doublet has wrong-sign kinetic and mass terms. We include the bounds coming from direct Higgs searches at both LEP and Tevatron using the code HiggsBounds, and show the currently excluded parameter space. We also analyze the prospects of LHC Run-I, finding that with a total integrated luminosity of 5 fb ^-1 and a center-of-mass energy of 7 TeV, most of the parameter space for the SM-like CP-even Higgs will be probed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1104/1104.3496v2.pdf"}
{"id": "1104.4737", "abstract": "  A \"strongly\" interacting, and entangling, heavy, non recoiling, external particle effects a significant change of the environment. Described locally, the corresponding entanglement event is a generalized electric Aharonov Bohm effect, that differs from the original one in a crucial way. We propose a gedanken interference experiment. The predicted shift of the interference pattern is due to a self induced or \"private\" potential difference experienced while the particle is in vacuum. We show that all non trivial Born Oppenheimer potentials are \"private\" potentials. We apply the Born Oppenheimer approximation to interference states. Using our approach we calculate the relative phase of the external heavy particle as well as its uncertainty throughout an interference experiment /entanglement event. We thus complement the Born Oppenheimer approximation for interference states. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1104/1104.4737v1.pdf"}
{"id": "1104.4830", "abstract": "  Using vector magnetograms obtained with the Spectro-polarimeter (SP) on aboard Hinode satellite, we studied two helicity parameters (local twist and current helicity) of 64 active regions occurred in the descending phase of solar cycle 23 and the ascending phase of solar cycle 24. Our analysis gives the following results. (1) The 34 active regions of the solar cycle 24 follow the so-called hemispheric helicity rule, whereas the 30 active regions of the solar cycle 23 do not. (2) When combining all 64 active regions as one sample, they follow the hemispheric helicity sign rule as in most other observations. (3) Despite with the so-far most accurate measurement of vector magnetic field given by SP/Hinode, the rule is still weak with large scatters. (4) The data show evidence of different helicity signs between strong and weak fields, confirming previous result from a large sample of ground-based observations. (5) With two example sunspots we show that the helicity parameters change sign from the inner umbra to the outer penumbra, where the sign of penumbra agrees with the sign of the active region as a whole. From these results, we speculate that both the Sigma-effect (turbulent convection) and the dynamo have contributed in the generation of helicity, whereas in both cases turbulence in the convection zone has played a significant role. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1104/1104.4830v1.pdf"}
{"id": "1104.5649", "abstract": "  We compute the geometric phase for a spin-1/2 particle under the presence of a composite environment, composed of an external bath (modeled by an infinite set of harmonic oscillators) and another spin-1/2 particle. We consider both cases: an initial entanglement between the spin-1/2 particles and an initial product state in order to see if the initial entanglement has an enhancement effect on the geometric phase of one of the spins. We follow the nonunitary evolution of the reduced density matrix and evaluate the geometric phase for a single two-level system. We also show that the initial entanglement enhances the sturdiness of the geometric phase under the presence of an external composite environment. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1104/1104.5649v1.pdf"}
{"id": "1105.0932", "abstract": "  We present a proposal for a versatile cold-atom-based quantum simulator of relativistic fermionic theories and topological insulators in arbitrary dimensions. The setup consists of a spin-independent optical lattice that traps a collection of hyperfine states of the same alkaline atom, to which the different degrees of freedom of the field theory to be simulated are then mapped. We show that the combination of bi-chromatic optical lattices with Raman transitions can allow the engineering of a spin-dependent tunneling of the atoms between neighboring lattice sites. These assisted-hopping processes can be employed for the quantum simulation of various interesting models, ranging from non-interacting relativistic fermionic theories to topological insulators. We present a toolbox for the realization of different types of relativistic lattice fermions, which can then be exploited to synthesize the majority of phases in the periodic table of topological insulators. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.0932v1.pdf"}
{"id": "1105.1222", "abstract": "  To help constrain the algorithms used in reconstructing high-energy muon events incident on the Sudbury Neutrino Observatory (SNO), a muon tracking system was installed. The system consisted of four planes of wire chambers, which were triggered by scintillator panels. The system was integrated with SNO's main data acquisition system and took data for a total of 95 live days. Using cosmic-ray events reconstructed in both the wire chambers and in SNO's water Cherenkov detector, the external muon tracking system was able to constrain the uncertainty on the muon direction to better than 0.6 degrees. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.1222v1.pdf"}
{"id": "1105.2521", "abstract": "  Using atomistic simulations we determine the roughness and the thermal properties of a suspended graphane sheet. As compared to graphene we found that hydrogenated graphene has: 1) a larger thermal contraction, 2) the roughness exponent at room temperature is smaller, i.e. ≃ 1.0 versus ≃ 1.2 for graphene, 3) the wave lengths of the induced ripples in graphane cover a wide range corresponding to length scales in the range (30-125) Åat room temperature, and 4) the heat capacity of graphane is estimated to be 29.32±0.23 J/molK which is 14.8", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.2521v1.pdf"}
{"id": "1105.3303", "abstract": "  A class of Emergent Universe (EU) model is studied in the light of recent observational data. Significant constraints on model parameters are obtained from the observational data. Density parameter for a class of model is evaluated. Some of the models are in favour of the recent observations. Some models have been found which are not interesting yielding unrealistic present day value of the density parameter. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.3303v1.pdf"}
{"id": "1105.4144", "abstract": "  We present a computer-assisted approach to coarse-graining the evolutionary dynamics of a system of nonidentical oscillators coupled through a (fixed) network structure. The existence of a spectral gap for the coupling network graph Laplacian suggests that the graph dynamics may quickly become low-dimensional. Our first choice of coarse variables consists of the components of the oscillator states -their (complex) phase angles- along the leading eigenvectors of this Laplacian. We then use the equation-free framework [1], circumventing the derivation of explicit coarse-grained equations, to perform computational tasks such as coarse projective integration, coarse fixed point and coarse limit cycle computations. In a second step, we explore an approach to incorporating oscillator heterogeneity in the coarse-graining process. The approach is based on the observation of fastdeveloping correlations between oscillator state and oscillator intrinsic properties, and establishes a connection with tools developed in the context of uncertainty quantification. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.4144v1.pdf"}
{"id": "1105.4440", "abstract": "  A comprehensive census of Galactic open cluster properties places unique constraints on the Galactic disc structure and evolution. In this framework we investigate the evolutionary status of three poorly-studied open clusters, Berkeley 31, Berkeley 23 and King 8, all located in the Galactic anti-centre direction. To this aim, we make use of deep LBT observations, reaching more than 6 mag below the main sequence Turn- Off. To determine the cluster parameters, namely age, metallicity, distance, reddening and binary fraction, we compare the observational colour-magnitude diagrams (CMDs) with a library of synthetic CMDs generated with different evolutionary sets (Padova, FRANEC and FST) and metallicities. We find that Berkeley 31 is relatively old, with an age between 2.3 and 2.9 Gyr, and rather high above the Galactic plane, at about 700 pc. Berkeley 23 and King 8 are younger, with best fitting ages in the range 1.1-1.3 Gyr and 0.8-1.3 Gyr, respectively. The position above the Galactic plane is about 500- 600 pc for the former, and 200 pc for the latter. Although a spectroscopic confirmation is needed, our analysis suggests a sub-solar metallicity for all three clusters. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.4440v1.pdf"}
{"id": "1105.6141", "abstract": "  We study a two-species bosonic Hubbard model on a two-dimensional square lattice by means of quantum Monte Carlo simulations. In addition to the usual contact repulsive interactions between the particles, the Hamiltonian has an interconversion term which allows the transformation of two particles from one species to the other. The phases are characterized by their solid or superfluid properties and by their polarization, i.e. the difference in the populations. When inter-species interactions are smaller than the intra-species ones, the system is unpolarized, whereas in the opposite case the system is unpolarized in even Mott insulator lobes and polarized in odd Mott lobes and also in the superfluid phase. We show that in the latter case the transition between the Mott insulator of total density two and the superfluid can be either of second or first order depending on the relative values of the interactions, whereas the transitions are continuous in all other cases. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.6141v2.pdf"}
{"id": "1106.0006", "abstract": "  Hard-core bosons on a triangular lattice with nearest neighbor repulsion are a prototypical example of a system with supersolid behavior on a lattice. We show that in this model the physical origin of the supersolid phase can be understood quantitatively and analytically by constructing quasiparticle excitations of defects that are moving on an ordered background. The location of the solid to supersolid phase transition line is predicted from the effective model for both positive and negative (frustrated) hopping parameters. For positive hopping parameters the calculations agree very accurately with numerical Quantum Monte Carlo simulations. The numerical results indicate that the supersolid to superfluid transition is first order. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.0006v2.pdf"}
{"id": "1106.0330", "abstract": "  Recommender systems are promising ways to filter the overabundant information in modern society. Their algorithms help individuals to explore decent items, but it is unclear how they allocate popularity among items. In this paper, we simulate successive recommendations and measure their influence on the dispersion of item popularity by Gini coefficient. Our result indicates that local diffusion and collaborative filtering reinforce the popularity of hot items, widening the popularity dispersion. On the other hand, the heat conduction algorithm increases the popularity of the niche items and generates smaller dispersion of item popularity. Simulations are compared to mean-field predictions. Our results suggest that recommender systems have reinforcing influence on global diversification. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.0330v1.pdf"}
{"id": "1106.2902", "abstract": "  In this work we perform a fractal analysis of 160 pieces of music belonging to six different genres. We show that the majority of the pieces reveal characteristics that allow us to classify them as physical processes called the 1/f (pink) noise. However, this is not true for classical music represented here by Frederic Chopin's works and for some jazz pieces that are much more correlated than the pink noise. We also perform a multifractal (MFDFA) analysis of these music pieces. We show that all the pieces reveal multifractal properties. The richest multifractal structures are observed for pop and rock music. Also the viariably of multifractal features is best visible for popular music genres. This can suggest that, from the multifractal perspective, classical and jazz music is much more uniform than pieces of the most popular genres of music. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.2902v1.pdf"}
{"id": "1106.3043", "abstract": "  We study a simple higher-dimensional toy model of electroweak symmetry breaking, in particular a pure gauge 5D theory on flat background with one extra finite space dimension. The principle of least action and the requirement of gauge independence of scattering amplitudes are used to determine the possible choices of boundary conditions. We demonstrate that for any of these choices the scattering amplitudes of vector bosons do not exhibit power-like growth in the high energy limit. Our analysis is an extension and generalization of the results obtained previously by other authors. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.3043v2.pdf"}
{"id": "1106.3167", "abstract": "  Electron coupling to intra- and inter-molecular vibrational modes is investigated in models appropriate to single crystal organic semiconductors, such as oligoacenes. Focus is on spectral and transport properties of these systems beyond perturbative approaches. The interplay between different couplings strongly affects the temperature band renormalization that is the result of a subtle equilibrium between opposite tendencies: band narrowing due to interaction with local modes, band widening due to electron coupling to non local modes. The model provides an accurate description of the mobility as function of temperature: indeed, it has the correct order of magnitude, at low temperatures, it scales as a power-law T^-δ with the exponent δ larger than unity, and, at high temperatures, shows an hopping behavior with a small activation energy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.3167v1.pdf"}
{"id": "1106.3935", "abstract": "  It is theoretically known that a pair of phase conjugating surfaces can function as a perfect lens, focusing propagating waves and enhancing evanescent waves. However, the known experimental approaches based on thin sheets of nonlinear materials cannot fully realize the required phase conjugation boundary condition. In this paper we show that the ideal phase conjugating surface is in principle physically realizable and investigate the necessary properties of nonlinear and nonreciprocal particles which can be used to build a perfect lens system. The physical principle of the lens operation is discussed in detail and directions of possible experimental realizations are outlined. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.3935v2.pdf"}
{"id": "1106.5312", "abstract": "  Nanson's and Baldwin's voting rules select a winner by successively eliminating candidates with low Borda scores. We show that these rules have a number of desirable computational properties. In particular, with unweighted votes, it is NP-hard to manipulate either rule with one manipulator, whilst with weighted votes, it is NP-hard to manipulate either rule with a small number of candidates and a coalition of manipulators. As only a couple of other voting rules are known to be NP-hard to manipulate with a single manipulator, Nanson's and Baldwin's rules appear to be particularly resistant to manipulation from a theoretical perspective. We also propose a number of approximation methods for manipulating these two rules. Experiments demonstrate that both rules are often difficult to manipulate in practice. These results suggest that elimination style voting rules deserve further study. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.5312v1.pdf"}
{"id": "1107.1258", "abstract": "  Space reddenings are derived for 15 Galactic Cepheids from dereddening CCD BVRIc data for AF-type stars in the immediate vicinities of the variables, in conjunction with 2MASS reddenings for BAF-type stars in the same fields. Potential reddening solutions were analyzed using the variable-extinction method to identify stars sharing potentially similar distances and reddenings to the Cepheids, several of which have large color excesses. The intrinsic BVRIc color relation for AF dwarfs was modified slightly in the analysis in order to describe better the colors observed for unreddened stars in the samples. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.1258v1.pdf"}
{"id": "1107.1442", "abstract": "  ATP-dependent chromatin remodeling enzymes (CRE) are bio-molecular motors in eukaryotic cells. These are driven by a chemical fuel, namely, adenosine triphosphate (ATP). CREs actively participate in many cellular processes that require accessibility of specific segments of DNA which are packaged as chromatin. The basic unit of chromatin is a nucleosome where 146 bp ∼ 50 nm of a double stranded DNA (dsDNA) is wrapped around a spool formed by histone proteins. The helical path of histone-DNA contact on a nucleosome is also called \"footprint\". We investigate the mechanism of footprint traversal by a CRE that translocates along the dsDNA. Our two-state model of a CRE captures effectively two distinct chemical (or conformational) states in the mechano-chemical cycle of each ATP-dependent CRE. We calculate the mean time of traversal. Our predictions on the ATP-dependence of the mean traversal time can be tested by carrying out in-vitro experiments on mono-nucleosomes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.1442v3.pdf"}
{"id": "1107.2259", "abstract": "  The modelling of electrical connections of single, or several, multiterminal quantum Hall effect (QHE) devices is relevant for electrical metrology: it is known, in fact, that certain particular connections allow i) the realization of multiples or fractions of the quantised resistance, or ii) the rejection of stray impedances, so that the configuration maintains the status of quantum standard. Ricketts-Kemeny and Delahaye equivalent circuits are known to be accurate models of the QHE: however, the numerical or analytical solution of electrical networks including these equivalent circuits can be difficult. In this paper, we introduce a method of analysis based on the representation of a QHE device by means of the indefinite admittance matrix: external connections are then represented with another matrix, easily written by inspection. Some examples, including the solution of double- and triple-series connections, are shown. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.2259v1.pdf"}
{"id": "1107.3358", "abstract": "  The HII region IC 1848 harbors a lot of intricate elephant trunk-like structures that look morphologically different from usual bright-rimmed clouds (BRCs). Of particular interest is a concentration of thin and long elephant trunk-like structures in the southeastern part of IC 1848E. Some of them have an apparently associated star (or two stars) at their very tip. We conducted VI_c photometry of several of these stars. Their positions on the V/(V-I_c) color-magnitude diagram as well as the physical parameters obtained by SED fittings indicate that they are low-mass pre-main-sequence stars having ages of mostly one Myr or less. This strongly suggests that they formed from elongated, elephant trunk-like clouds. We presume that such elephant trunk-like structures are genetically different from BRCs, on the basis of the differences in morphology, size distributions, and the ages of the associated young stars. We suspect that those clouds have been caused by hydrodynamical instability of the ionization/shock front of the expanding HII region. Similar structures often show up in recent numerical simulations of the evolution of HII regions. We further hypothesize that this mechanism makes a third mode of triggered star formation associated with HII regions, in addition to the two known mechanisms, i.e., collect-and-collapse of the shell accumulated around an expanding HII region and radiation-driven implosion of BRCs originated from pre-existing cloud clumps. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.3358v1.pdf"}
{"id": "1107.3812", "abstract": "  Higher order Laguerre-Gauss (LG) beams have been proposed for use in future gravitational wave detectors, such as upgrades to the Advanced LIGO detectors and the Einstein Telescope, for their potential to reduce the effects of the thermal noise of the test masses. This paper details the theoretical analysis and simulation work carried out to investigate the behaviour of LG beams in realistic optical setups, in particular the coupling between different LG modes in a linear cavity. We present a new analytical approximation to compute the coupling between modes, using Zernike polynomials to describe mirror surface distortions. We apply this method in a study of the behaviour of the LG33 mode within realistic arm cavities, using measured mirror surface maps from the Advanced LIGO project. We show mode distortions that can be expected to arise due to the degeneracy of higher order spatial modes within such cavities and relate this to the theoretical analysis. Finally we identify the mirror distortions which cause significant coupling from the LG33 mode into other order 9 modes and derive requirements for the mirror surfaces. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.3812v1.pdf"}
{"id": "1107.4125", "abstract": "  We present a theoretical approach to describing the Mott transition of electrons on a two dimensional lattice that begins with the low energy effective theory of the Fermi liquid. The approach to the Mott transition must be characterized by the suppression of density and current fluctuations which correspond to specific shape deformations of the Fermi surface. We explore the nature of the Mott insulator and the corresponding Mott transition when these shape fluctuations of the Fermi surface are suppressed without making any a prior assumptions about other Fermi surface shape fluctuations. Building on insights from the theory of the Mott transition of bosons, we implement this suppression by identifying and condensing vortex degrees of freedom in the phase of the low energy electron operator. We show that the resulting Mott insulator is a quantum spin liquid with a spinon fermi surface coupled to a U(1) gauge field which is usually described within a slave particle formulation. Our approach thus provides a coarse-grained treatment of the Mott transition and the proximate spin liquid that is nevertheless equivalent to the standard slave particle construction. This alternate point of view provides further insight into the novel physics of the Mott transition and the spin liquid state that is potentially useful. We describe a generalization that suppresses spin anti-symmetric fluctuations of the Fermi surface that leads to a spin-gapped charge metal previously also discussed in terms of slave particle constructions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.4125v1.pdf"}
{"id": "1107.5182", "abstract": "  We present a framework for the analysis of transport processes resulting from the mean-eddy interaction in a flow. The framework is based on the Transport Induced by the Mean-Eddy Interaction (TIME) method presented in a companion paper <cit.>. The TIME method estimates the (Lagrangian) transport across stationary (Eulerian) boundaries defined by chosen streamlines of the mean flow. Our framework proceeds after first carrying out a sequence of preparatory steps that link the flow dynamics to the transport processes. This includes the construction of the so-called \"instantaneous flux\" as the Hovmöller diagram. Transport processes are studied by linking the signals of the instantaneous flux field to the dynamical variability of the flow. This linkage also reveals how the variability of the flow contributes to the transport. The spatio-temporal analysis of the flux diagram can be used to assess the efficiency of the variability in transport processes. We apply the method to the double-gyre ocean circulation model in the situation where the Rossby-wave mode dominates the dynamic variability. The spatio-temporal analysis shows that the inter-gyre transport is controlled by the circulating eddy vortices in the fast eastward jet region, whereas the basin-scale Rossby waves have very little impact. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.5182v1.pdf"}
{"id": "1108.0919", "abstract": "  We present a calibration of the acquisition data obtained by the Red Peak-Up (PU) sub-array on the Infrared Spectrograph on Spitzer, based on repeated observations of three K giants. This calibration is tied directly to the most current infrared calibration based on data from Multiband Imaging Photometer for Spitzer. An analysis of the responsivity of the Red PU sub-array reveals no detectable deviations from linearity in the most recent pipeline version, but older pipeline versions show evidence suggesting possible small non-linearities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.0919v2.pdf"}
{"id": "1108.2356", "abstract": "  According to Hansen, Madow and Tepping [J. Amer. Statist. Assoc. 78 (1983) 776–793], \"Probability sampling designs and randomization inference are widely accepted as the standard approach in sample surveys.\" In this article, reasons are advanced for the wide use of this design-based approach, particularly by federal agencies and other survey organizations conducting complex large scale surveys on topics related to public policy. Impact of Bayesian methods in survey sampling is also discussed in two different directions: nonparametric calibrated Bayesian inferences from large samples and hierarchical Bayes methods for small area estimation based on parametric models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.2356v1.pdf"}
{"id": "1108.2648", "abstract": "  If general relativity is spontaneously induced, that is if the reciprocal Newton constant serves as a VEV, the electrically charged black hole limit is governed by a Davidson-Gurwich phase transition which occurs precisely at the would have been outer horizon. The transition profile which connects the exterior Reissner-Nordstrom solution with the novel interior is analytically derived. The inner core is characterized by a vanishing spatial volume and constant surface gravity, and in some respects, resembles a maximally stretched horizon. The Komar mass residing inside any concentric interior sphere is proportional to the surface area of that sphere, and consequently, is non-negative definite and furthermore non-singular at the origin. The Kruskal structure is recovered, admitting the exact Hawking imaginary time periodicity, but unconventionally, with the conic defect defused at the origin. The corresponding holographic entropy packing locally saturates the 't Hooft-Susskind-Bousso holographic bound, thus making the core Nature's ultimate information storage. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.2648v1.pdf"}
{"id": "1108.2807", "abstract": "  Fermionic 87Sr has a nuclear spin of I=9/2, higher than any other element with similar electronic structure. This large nuclear spin has many applications in quantum simulation and computation, for which preparation and detection of the spin state are requirements. For an ultracold 87Sr cloud, we show two complementary methods to characterize the spin-state mixture: optical Stern-Gerlach state separation and state-selective absorption imaging. We use these methods to optimize the preparation of a variety of spin-state mixtures by optical pumping and to measure an upper bound of the 87Sr spin relaxation rate. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.2807v1.pdf"}
{"id": "1108.3528", "abstract": "  We have measured the alignment of the L-shell magnetic-substates following the K-shell excitation of hydrogen- and helium-like uranium in relativistic collisions with a low-Z gaseous target. Within this experiment the population distribution for the L-shell magnetic sublevels has been obtained via an angular differential study of the decay photons associated with the subsequent de-excitation process. The results show a very distinctive behavior for the H- and He-like heavy systems. In particular for K → L excitation of He-like uranium, a considerable alignment of the L-shell levels was observed. A comparison of our experimental findings with recent rigorous relativistic predictions provides a good qualitative and a reasonable quantitative agreement, emphasizing the importance of the magnetic-interaction and many-body effects in the strong-field domain of high-Z ions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.3528v1.pdf"}
{"id": "1108.4650", "abstract": "  We study the radiative heat transfer and the Casimir-Lifshitz force occurring between two bodies in a system out of thermal equilibrium. We consider bodies of arbitrary shape and dielectric properties, held at two different temperatures, and immersed in a environmental radiation at a third different temperature. We derive explicit closed-form analytic expressions for the correlations of the electromagnetic field, and for the heat transfer and Casimir-Lifshitz force, in terms of the bodies scattering matrices. We then consider some particular cases which we investigate in detail: the atom-surface and the slab-slab configurations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.4650v2.pdf"}
{"id": "1109.2068", "abstract": "  Relativistic spectral lines from the accretion disc of a neutron star low-mass X-ray binary can be modelled to infer the disc inner edge radius. A small value of this radius tentatively implies that the disc terminates either at the neutron star hard surface, or at the innermost stable circular orbit (ISCO). Therefore an inferred disc inner edge radius either provides the stellar radius, or can directly constrain stellar equation of state (EoS) models using the theoretically computed ISCO radius for the spacetime of a rapidly spinning neutron star. However, this procedure requires numerical computation of stellar and ISCO radii for various EoS models and neutron star configurations using an appropriate rapidly spinning stellar spacetime. We have fully general relativistically calculated about 16000 stable neutron star structures to explore and establish the above mentioned procedure, and to show that the Kerr spacetime is inadequate for this purpose. Our work systematically studies the methods to constrain EoS models using relativistic disc lines, and will motivate future X-ray astronomy instruments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1109/1109.2068v1.pdf"}
{"id": "1109.2453", "abstract": "  Electron spin resonance (ESR) spectroscopy is an important tool to characterize the ground state of conduction electrons and to measure their spin-relaxation times. Observing ESR of the itinerant electrons is thus of great importance in graphene and in single-wall carbon nanotubes (SWCNTs). Often, the identification of CESR signal is based on two facts: the apparent asymmetry of the ESR signal (known as a Dysonian lineshape) and on the temperature independence of the ESR signal intensity. We argue that these are insufficient as benchmarks and instead the ESR signal intensity (when calibrated against an intensity reference) yields an accurate characterization. We detail the method to obtain the density of states from an ESR signal, which can be compared with theoretical estimates. We demonstrate the success of the method for K doped graphite powder. We give a benchmark for the observation of ESR in graphene. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1109/1109.2453v2.pdf"}
{"id": "1109.2854", "abstract": "  We present large field HI-line emission maps obtained with the single-dish Green Bank Telescope centered on the dwarf irregular galaxies Sextans A, NGC 2366, and WLM. We do not detect the extended skirts of emission associated with the galaxies that were reported from Effelsberg observations (Huchtmeier et al. 1981). The ratio of HI at 10^19 atoms cm^-2 to optical extents of these galaxies are instead 2–3, which is normal for this type of galaxy. There is no evidence for a truncation in the HI distribution >/=10^19 atoms cm^-2. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1109/1109.2854v1.pdf"}
{"id": "1109.3101", "abstract": "  We report on a joint experimental-theoretical study of collective diffusion in, and static shear viscosity of solutions of bovine serum albumin (BSA) proteins, focusing on the dependence on protein and salt concentration. Data obtained from dynamic light scattering and rheometric measurements are compared to theoretical calculations based on an analytically treatable spheroid model of BSA with isotropic screened Coulomb plus hard-sphere interactions. The only input to the dynamics calculations is the static structure factor obtained from a consistent theoretical fit to a concentration series of small-angle X-ray scattering (SAXS) data. This fit is based on an integral equation scheme that combines high accuracy with low computational cost. All experimentally probed dynamic and static properties are reproduced theoretically with an at least semi-quantitative accuracy. For lower protein concentration and low salinity, both theory and experiment show a maximum in the reduced viscosity, caused by the electrostatic repulsion of proteins. The validity range of a generalized Stokes-Einstein (GSE) relation connecting viscosity, collective diffusion coefficient, and osmotic compressibility, proposed by Kholodenko and Douglas [PRE 51, 1081 (1995)] is examined. Significant violation of the GSE relation is found, both in experimental data and in theoretical models, in semi-dilute systems at physiological salinity, and under low-salt conditions for arbitrary protein concentrations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1109/1109.3101v1.pdf"}
{"id": "1109.5155", "abstract": "  A phenomenological formalism is presented in which the apparent acceleration of the universe is generated by large-scale structure formation, thus eliminating the magnitude and coincidence fine-tuning problems of the Cosmological Constant in the Concordance Model, as well as potential instability issues with dynamical Dark Energy. The observed acceleration results from the combined effect of innumerable local perturbations due to individually virializing systems, overlapping together in a smoothly-inhomogeneous adjustment of the FRW metric, in a process governed by the causal flow of inhomogeneity information outward from each clumped system. After explaining why arguments from the literature claiming to place restrictive limits upon backreaction are not applicable in a physically realistic cosmological analysis, we present a selection of simply-parameterized models which are capable of fitting the luminosity distance data from Type Ia supernovae essentially as well as the best-fit flat ΛCDM model, without resort to Dark Energy, any modification to gravity, or a local void. Simultaneously, these models can reproduce measured cosmological parameters such as the age of the universe, the matter density required for spatial flatness, the present-day deceleration parameter, and the angular scale of the Cosmic Microwave Background to within a reasonable proximity of their Concordance values. A potential observational signature for distinguishing this cosmological formalism from ΛCDM may be a cosmic jerk parameter significantly in excess of unity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1109/1109.5155v3.pdf"}
{"id": "1110.2259", "abstract": "  Latest results are presented in the search for low mass standard model Higgs production in association with a W boson, based on large luminosity data samples collected at the CDF and D0 Experiments at the Fermilab Tevatron pp̅ collider. The selection of event samples containing an isolated lepton, an imbalance in transverse energy in the events, and either one or two reconstructed jets consistent with having evolved from a b-quark, provides statistically independent data samples to search for qq̅→ WH candidates. Expected and observed upper limits are derived for the product of the WH production cross section and branching ratios and are reported in units of the standard model prediction. The observed (expected) upper limits for a Higgs mass M_H=115   GeV are factors 2.65 (2.6) and 4.6 (3.5) above the standard model prediction for the CDF and D0 searches, respectively. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.2259v1.pdf"}
{"id": "1110.3245", "abstract": "  We study how the properties of transient sources of ultra-high-energy cosmic rays (UHECRs) can be accessed by exploiting UHECR experiments, taking into account the propagation of UHECRs in magnetic structures which the sources are embedded in, i.e., clusters of galaxies and filamentary structures. Adopting simplified analytical models, we demonstrate that the structured extragalactic magnetic fields (EGMFs) play crucial roles in unveiling the properties of the transient sources. These EGMFs unavoidably cause significant delay in the arrival time of UHECRs as well as the Galactic magnetic field, even if the strength of magnetic fields in voids is zero. Then, we show that, given good knowledge on the structured EGMFs, UHECR observations with high statistics above 10^20 eV allow us to constrain the generation rate of transient UHECR sources and their energy input per burst, which can be compared with the rates and energy release of known astrophysical phenomena. We also demonstrate that identifying the energy dependence of the apparent number density of UHECR sources at the highest energies is crucial as a clue to such transient sources. Future UHECR experiments with extremely large exposure are required to reveal the nature of transient UHECR sources. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.3245v2.pdf"}
{"id": "1110.3593", "abstract": "  Previously a set of coupled first order differential equations were derived for the decoherence of a pair of spatial mode entangled photons, propagating along different paths through turbulence. Here we extend this analysis to the situation where both photons travel along the same path, which introduces the effect of multiple photon correlations. The resulting equation now contains additional terms that take these multiphoton correlations into account. At the same time, we provide a more thorough formulation of the quantized field, starting from a Lorentz invariant formulation, which is then explicitly broken by the choice of a particular propagation direction. The effect of the latter improvement in the quantization on the form of the final equation is minimal. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.3593v1.pdf"}
{"id": "1110.4192", "abstract": "  During the past 20 years, the idea that non-spherical planetary nebulae (PN) may need a binary or planetary interaction to be shaped was discussed by various authors. It is now generally agreed that the varied morphologies of PN cannot be fully explained solely by single star evolution. Observationally, more binary central stars of planetary nebulae (CSPN) have been discovered, opening new possibilities to understand the connections between binarity and morphology. So far, ≃45 binary CSPN have been detected, most being close systems detected via flux variability. To determine the PN binary fraction, one needs a method to detect wider binaries. We present here recent results obtained with the various techniques described, concentrating on binary infrared excess observations aimed at detecting binaries of any separation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.4192v3.pdf"}
{"id": "1110.4237", "abstract": "  As indicated by the recent data obtained by the T2K and the MINOS experiments θ_13 can be large, even be comparable to the Chooz limit. Assuming that it will be confirmed by ongoing reactor and accelerator experiments I discuss its possible implications in the context of how to explore the remaining unknowns in the lepton flavor mixing. While it opens wide range of possibilities to explore CP and the mass hierarchy, I emphasize that the large θ_13 allows us to take \"all in one\" (everything in a lunch box) approach. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.4237v1.pdf"}
{"id": "1110.5198", "abstract": "  In this paper, gravothermal oscillations are investigated in two-component clusters with a range of different stellar mass ratios and total component mass ratios. The critical number of stars at which gravothermal oscillations first appeared is found using a gas code. The nature of the oscillations is investigated and it is shown that the oscillations can be understood by focusing on the behaviour of the heavier component, because of mass segregation. It is argued that, during each oscillation, the re-collapse of the cluster begins at larger radii while the core is still expanding. This re-collapse can halt and reverse a gravothermally driven expansion. This material outside the core contracts because it is losing energy both to the cool expanding core and to the material at larger radii. The core collapse times for each model are also found and discussed. For an appropriately chosen case, direct N -body runs were carried out, in order to check the results obtained from the gas model, including evidence of the gravothermal nature of the oscillations and the temperature inversion that drives the expansion. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.5198v1.pdf"}
{"id": "1111.0033", "abstract": "  Human dynamics is known to be inhomogeneous and bursty but the detailed understanding of the role of human factors in bursty dynamics is still lacking. In order to investigate their role we devise an agent-based model, where an agent in an uncertain situation tries to reduce the uncertainty by communicating with information providers while having to wait time for responses. Here the waiting time can be considered as cost. We show that the optimal choice of the waiting time under uncertainty gives rise to the bursty dynamics, characterized by the heavy-tailed distribution of optimal waiting time. We find that in all cases the efficiency for communication is relevant to the scaling behavior of the optimal waiting time distribution. On the other hand the cost turns out in some cases to be irrelevant depending on the degree of uncertainty and efficiency. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.0033v3.pdf"}
{"id": "1111.0378", "abstract": "  The synergy between the Fermi-LAT and ground-based Cherenkov telescope arrays gives us the opportunity for the first time to characterize the high energy emission (100 MeV - 10 TeV) from more than 30 blazars. In this study we performed a Fermi-LAT spectral analysis for all TeV-detected blazars and combined it with archival TeV spectra. Our results for low synchrotron-peaked BL Lacs (LBL) show hints of absorption features in the GeV band that could be interpreted as internal opacity at the source. We note that simple or broken power laws cannot describe all the observed GeV-TeV spectra and more complex spectral shapes seem required. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.0378v1.pdf"}
{"id": "1111.0430", "abstract": "  Blazars are jet-dominated extragalactic objects characterized by the emission of strongly variable non-thermal radiation across the entire electromagnetic spectrum. Therefore, the study of blazars (and in general of radio loud AGN) through the use of multi-frequency simultaneous data is essential in order to understand the physical processes that take place in these objects. With Planck, Fermi and Swift simultaneously on orbit, complemented with other space and ground-based observatories, it is possible to assemble high-quality multi-frequency simultaneous broad-band spectra of large and statistically well-defined samples of radio-loud AGN. In particular, four samples of sources have been selected. The first three samples are flux limited in the high energy part of the electromagnetic spectrum: the soft X-ray (0.1-2 keV) sample includes 43 sources from the Rosat All Sky Survey Bright Source Catalog, the hard X-ray (15-150 keV) sample includes 34 sources from the Swift-BAT 54 months source catalog and the gamma-ray sample includes 50 sources from the Fermi-LAT 3 months Bright AGN Source List. The fourth sample is radio flux limited, including 104 bright northern and equatorial radio-loud AGN (most of which have been monitored at Metsahovi Radio Observatory for many years) with average radio flux density at 37 GHz greater than 1 Jy. We present the methods applied and the results of the analysis performed using Fermi-LAT data for all sources in the four different samples of AGN. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.0430v1.pdf"}
{"id": "1111.0441", "abstract": "  The recent measurements of the elastic cross section by the TOTEM Collaboration together with the first estimations of the inelastic cross sections by other LHC detectors are used to test the simplest version of the geometrical model of the proton-proton scattering. We show that the description found for lower energy data, with the modest adjustment of the model parameter extrapolation, could be, in principle, used to describe the LHC measurement and to predict the cross sections in very high energy cosmic ray domain. However, the shape of the first elastic dip in the elastic differential scattering cross section suggests that ratio of the real to the imaginary part of the elastic amplitude is falling rather fast and the analysis of the elastic cross section fraction suggests that the geometrical picture of the proton-proton collision should be modified considerably when entering the ultra high-energy domain. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.0441v1.pdf"}
{"id": "1111.0456", "abstract": "  It is known from numerical simulations that thermal conduction along magnetic field lines plays an important role in the evolution of the kink instability in coronal loops. This study presents the observational signatures of the kink instability in long coronal loops when parallel thermal conduction is included. The 3D nonlinear magnetohydrodynamic equations are solved numerically to simulate the evolution of a coronal loop that is initially in an unstable equilibrium. The loop has length 80 Mm, width 8 Mm and an initial maximum twist of Phi = 11.5 pi, where Phi is a function of the radius. The initial loop parameters are obtained from a highly twisted loop observed in the TRACE 171 A waveband. Synthetic observables are generated from the data. These observables include spatial and temporal averaging to account for the resolution and exposure times of TRACE images. Parallel thermal conduction reduces the maximum local temperature by up to an order of magnitude. This means that different spectral lines are formed and different internal loop structures are visible with or without the inclusion of thermal conduction. However, the response functions sample a broad range of temperatures. The result is that the inclusion of parallel thermal conductivity does not have as large an impact on observational signatures as the order of magnitude reduction in the maximum temperature would suggest; the net effect is a blurring of internal features of the loop structure. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.0456v1.pdf"}
{"id": "1111.0921", "abstract": "  We study synchronization of sinusoidally coupled phase oscillators on networks with modular structure and a large number of oscillators in each community. Of particular interest is the hierarchy of local and global synchrony, i.e., synchrony within and between communities, respectively. Using the recent ansatz of Ott and Antonsen, we find that the degree of local synchrony can be determined from a set of coupled low-dimensional equations. If the number of communities in the network is large, a low-dimensional description of global synchrony can be also found. Using these results, we study bifurcations between different types of synchrony. We find that, depending on the relative strength of local and global coupling, the transition to synchrony in the network can be mediated by local or global effects. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.0921v2.pdf"}
{"id": "1111.3682", "abstract": "  Over the last decade, evidence has mounted that the solar system's observed state can be favorably reproduced in the context of an instability-driven dynamical evolution model, such as the \"Nice\" model. To date, all successful realizations of instability models have concentrated on evolving the four giant planets onto their current orbits from a more compact configuration. Simultaneously, the possibility of forming and ejecting additional planets has been discussed, but never successfully implemented. Here we show that a large array of 5-planet (2 gas giants + 3 ice giants) multi-resonant initial states can lead to an adequate formation of the outer solar system, featuring an ejection of an ice giant during a phase of instability. Particularly, our simulations demonstrate that the eigenmodes which characterize the outer solar system's secular dynamics can be closely matched with a 5-planet model. Furthermore, provided that the ejection timescale of the extra planet is short, orbital excitation of a primordial cold classical Kuiper belt can also be avoided in this scenario. Thus the solar system is one of many possible outcomes of dynamical relaxation and can originate from a wide variety of initial states. This deems the construction of a unique model of solar system's early dynamical evolution impossible. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.3682v1.pdf"}
{"id": "1111.3813", "abstract": "  We relate the Z_2 gauge theory formalism of the Kitaev model to the SU(2) gauge theory of the resonating valence bond (RVB) physics. Further, we reformulate a known Jordan-Wigner transformation of Kitaev model on a torus in a general way that shows that it can be thought of as a Z_2 gauge fixing procedure. The conserved quantities simplify in terms of the gauge invariant Jordan-Wigner fermions, enabling us to construct exact eigen states and calculate physical quantities. We calculate the fermionic spectrum for flux free sector for different gauge field configurations and show that the ground state is four-fold degenerate on a torus in thermodynamic limit. Further on a torus we construct four mutually anti-commuting operators which enable us to prove that all eigenstates of this model are four fold degenerate in thermodynamic limit. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.3813v2.pdf"}
{"id": "1111.4032", "abstract": "  We present the analysis of the light curves of 9 high-magnification single-lens gravitational microlensing events with lenses passing over source stars, including OGLE-2004-BLG-254, MOA-2007-BLG-176, MOA-2007-BLG-233/OGLE-2007-BLG-302, MOA-2009-BLG-174, MOA-2010-BLG-436, MOA-2011-BLG-093, MOA-2011-BLG-274, OGLE-2011-BLG-0990/MOA-2011-BLG-300, and OGLE-2011-BLG-1101/MOA-2011-BLG-325. For all events, we measure the linear limb-darkening coefficients of the surface brightness profile of source stars by measuring the deviation of the light curves near the peak affected by the finite-source effect. For 7 events, we measure the Einstein radii and the lens-source relative proper motions. Among them, 5 events are found to have Einstein radii less than 0.2 mas, making the lenses candidates of very low-mass stars or brown dwarfs. For MOA-2011-BLG-274, especially, the small Einstein radius of θ_ E∼ 0.08 mas combined with the short time scale of t_ E∼ 2.7 days suggests the possibility that the lens is a free-floating planet. For MOA-2009-BLG-174, we measure the lens parallax and thus uniquely determine the physical parameters of the lens. We also find that the measured lens mass of ∼ 0.84 M_⊙ is consistent with that of a star blended with the source, suggesting that the blend is likely to be the lens. Although we find planetary signals for none of events, we provide exclusion diagrams showing the confidence levels excluding the existence of a planet as a function of the separation and mass ratio. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.4032v2.pdf"}
{"id": "1111.4344", "abstract": "  A new Skyrme-like energy density suitable for studies of strongly elongated nuclei has been determined in the framework of the Hartree-Fock-Bogoliubov theory using the recently developed model-based, derivative-free optimization algorithm POUNDerS. A sensitivity analysis at the optimal solution has revealed the importance of states at large deformations in driving the parameterization of the functional. The good agreement with experimental data on masses and separation energies, achieved with the previous parameterization UNEDF0, is largely preserved. In addition, the new energy density UNEDF1 gives a much improved description of the fission barriers in 240Pu and neighboring nuclei. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.4344v2.pdf"}
{"id": "1111.5782", "abstract": "  The behaviour of two-dimensional patchy particles with 5 and 7 regularly-arranged patches is investigated by computer simulation. For higher pressures and wider patch widths, hexagonal crystals have the lowest enthalpy, whereas at lower pressures and for narrower patches, lower-density crystals with five nearest neighbours and that are based on the (3^2,4,3,4) tiling of squares and triangles become lower in enthalpy. Interestingly, in regions of parameter space near to that where the hexagonal crystals become stable, quasicrystalline structures with dodecagonal symmetry form on cooling from high temperature. These quasicrystals can be considered as tilings of squares and triangles, and are probably stabilized by the large configurational entropy associated with all the different possible such tilings. The potential for experimentally realizing such structures using DNA multi-arm motifs are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.5782v1.pdf"}
{"id": "1111.5984", "abstract": "  The photon polarization tensor is the central building block of an effective theory description of photon propagation in the quantum vacuum. It accounts for the vacuum fluctuations of the underlying theory, and in the presence of external electromagnetic fields, gives rise to such striking phenomena as vacuum birefringence and dichroism. Standard approximations of the polarization tensor are often restricted to on-the-light-cone dynamics in homogeneous electromagnetic fields, and are limited to certain momentum regimes only. We devise two different strategies to go beyond these limitations: First, we aim at obtaining novel analytical insights into the photon polarization tensor for homogeneous fields, while retaining its full momentum dependence. Second, we employ wordline numerical methods to surpass the constant-field limit. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.5984v2.pdf"}
{"id": "1111.6607", "abstract": "  We develop a semi-analytical approach, based on the post-Newtonian expansion and on the affine approximation, to model the tidal deformation of neutron stars in the coalescence of black hole-neutron star or neutron star-neutron star binaries. Our equations describe, in a unified framework, both the system orbital evolution, and the neutron star deformations. These are driven by the tidal tensor, which we expand at 1/c^3 post-Newtonian order, including spin terms. We test the theoretical framework by simulating black hole-neutron star coalescence up to the onset of mass shedding, which we determine by comparing the shape of the star with the Roche lobe. We validate our approach by comparing our results with those of fully relativistic, numerical simulations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.6607v3.pdf"}
{"id": "1111.7268", "abstract": "  In this article an idea is presented, which allows for the explanation of superluminal muon neutrinos. It is based on the introduction of a new superluminal, massless gauge boson coupling to the neutrino only, but not to other standard model particles. The model is discussed with regard to the Supernova 1987 (SN 1987) velocity bound on electron antineutrinos and the Cohen-Glashow constraint on superluminal neutrino propagation. The latter can be circumvented if - within the framework of the model - a sterile neutrino mixing with the active neutrino mass eigenstates is introduced. The suggestion of a sterile neutrino accounting for superluminal neutrinos has already been proposed in several papers. It is possible to choose mixing angles with the sterile neutrino sector such that the model respects both the SN 1987 bound and the muon neutrino travels superluminally. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.7268v3.pdf"}
{"id": "1112.0952", "abstract": "  We present a brief overview of the theory of stellar winds with a strong emphasis on the radiation-driven outflows from massive stars. The resulting implications for the evolution and fate of massive stars are also discussed. Furthermore, we relate the effects of mass loss to the angular momentum evolution, which is particularly relevant for the production of long and soft gamma-ray bursts. Mass-loss rates are not only a function of the metallicity, but are also found to depend on temperature, particularly in the region of the bi-stability jump at 21 000 Kelvin. We highlight the role of the bi-stability jump for Luminous Blue Variable (LBV) stars, and discuss suggestions that LBVs might be direct progenitors of supernovae. We emphasize that radiation-driven wind studies rely heavily on the input opacity data and linelists, and that these are thus of fundamental importance to both the mass-loss predictions themselves, as well as to our overall understanding of the lives and deaths of massive stars. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.0952v1.pdf"}
{"id": "1112.3178", "abstract": "  Pairing plays a central role in nuclear systems. The simplest model for the pairing is the constant-pairing Hamiltonian. The aim of the present paper is to include the continuum single particle level density in the constant pairing Hamiltonian and to make a comparison between the approximate BCS and the exact Richardson solutions. The continuum is introduced by using the continuum single particle level density. It is shown that the continuum makes an important contribution to the pairing parameter even in those case when the continuum is weakly populated. It is shown that while the approximate BCS solution depends on the model space the exact Richardson solution does not. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.3178v2.pdf"}
{"id": "1112.3816", "abstract": "  In this paper we consider a bosonic Josephson junction described by a two-mode Bose-Hubbard model, and we thoroughly analyze a quantum phase transition occurring in the system in the limit of infinite bosonic population. We discuss the relation between this quantum phase transition and the dynamical bifurcation occurring in the spectrum of the Discrete Self Trapping equations describing the system at the semiclassical level. In particular, we identify five regimes depending on the strength of the effective interaction among bosons, and study the finite-size effects arising from the finiteness of the bosonic population. We devote a special attention to the critical regime which reduces to the dynamical bifurcation point in the thermodynamic limit of infinite bosonic population. Specifically, we highlight an anomalous scaling in the population imbalance between the two wells of the trapping potential, as well as in two quantities borrowed from Quantum Information Theory, i.e. the entropy of entanglement and the ground-state fidelity. Our analysis is not limited to the zero temperature case, but considers thermal effects as well. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.3816v2.pdf"}
{"id": "1201.3201", "abstract": "  We prove a Rademacher-type theorem for Lipschitz mappings from a subset of a Carnot group to a Banach homogeneous group, equipped with a suitably weakened Radon-Nikodym property. We provide a metric area formula that applies to these mappings and more generally to all almost everywhere metrically differentiable Lipschitz mappings defined on a Carnot group. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1201/1201.3201v1.pdf"}
{"id": "1201.4969", "abstract": "  We discuss the role of the long-range elastic interaction between the contacts inside an inhomogeneous frictional interface. The interaction produces a characteristic elastic correlation length λ_c = a^2 E / k_c (where a is the distance between the contacts, k_c is the elastic constant of a contact, and E is the Young modulus of the sliding body), below which the slider may be considered as a rigid body. The strong inter-contact interaction leads to a narrowing of the effective threshold distribution for contact breaking and enhances the chances for an elastic instability to appear. Above the correlation length, r > λ_c, the interaction leads to screening of local perturbations in the interface, or to appearance of collective modes — frictional cracks propagating as solitary waves. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1201/1201.4969v1.pdf"}
{"id": "1201.6474", "abstract": "  The low temperature electronic and galvanomagnetic transport properties of the low dimensional oxide KRu_4O_8 are experimentally considered. A quadratic temperature variation of the resistivity is observed to be proportional to the residual resistivity. It shows the role of inelastic electron scattering against impurities, i.e. a large Koshino-Taylor effect, rather than a consequence of strong electronic correlations. In the same temperature range, the Kohler rule is not fulfilled. The resistance noise increases also sharply, possibly due to a strong coupling of carriers with lattice fluctuations in this low dimensional compound. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1201/1201.6474v1.pdf"}
{"id": "1202.3616", "abstract": "  We formulated an effective theory for a single interlayer exciton in a bilayer quantum antiferromagnet, in the limit that the holon and doublon are strongly bound onto one interlayer rung by the Coulomb force. Upon using a rung linear spin wave approximation of the bilayer Heisenberg model, we calculated the spectral function of the exciton for a wide range of the interlayer Heisenberg coupling α=J_⊥/Jz. In the disordered phase at large α, a coherent quasiparticle peak appears representing free motion of the exciton in a spin singlet background. In the Néel phase, which applies to more realistic model parameters, a ladder spectrum arises due to Ising confinement of the exciton. The exciton spectrum is visible in measurements of the dielectric function, such as c-axis optical conductivity measurements. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.3616v3.pdf"}
{"id": "1202.5450", "abstract": "  Today's data-heavy research environment requires the integration of different sources of information into structured data sets that can not be analyzed as simple matrices. We introduce an old technique, known in the European data analyses circles as the Duality Diagram Approach, put to new uses through the use of a variety of metrics and ways of combining different diagrams together. This issue of the Annals of Applied Statistics contains contemporary examples of how this approach provides solutions to hard problems in data integration. We present here the genesis of the technique and how it can be seen as a precursor of the modern kernel based approaches. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.5450v1.pdf"}
{"id": "1202.5545", "abstract": "  We study the low-temperature properties of a one-dimensional spin-1/2 chain of magnetic impurities coupled to a (normal) metal environment by means of anisotropic Kondo exchange. In the case of easy-plane anisotropy, we obtain the phase diagram of this system at T=0. We show that the in-plane Kondo coupling destabilizes the Tomonaga-Luttinger phase of the spin-chain, and leads to two different phases: i) At strong Kondo coupling, the spins in the chain form Kondo singlets and become screened by the metallic environment, and ii) At weak and intermediate Kondo coupling, we find a novel dissipative phase characterized by diffusive gapless spin excitations. The two phases are separated by a quantum critical point of the Wilson-Fisher universality class with dynamical exponent z≃2. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.5545v2.pdf"}
{"id": "1202.5586", "abstract": "  It was recently pointed out that topological liquid phases arising in the fractional quantum Hall effect (FQHE) are not required to be rotationally invariant, as most variational wavefunctions proposed to date have been. Instead, they possess a geometric degree of freedom corresponding to a shear deformation that acts like an intrinsic metric. We apply this idea to a system with an anisotropic band mass, as is intrinsically the case in many-valley semiconductors such as AlAs and Si, or in isotropic systems like GaAs in the presence of a tilted magnetic field, which breaks the rotational invariance. We perform exact diagonalization calculations with periodic boundary conditions (torus geometry) for various filling fractions in the lowest, first and second Landau levels. In the lowest Landau level, we demonstrate that FQHE states generally survive the breakdown of rotational invariance by moderate values of the band mass anisotropy. At 1/3 filling, we generate a variational family of Laughlin wavefunctions parametrized by the metric degree of freedom. We show that the intrinsic metric of the Laughlin state adjusts as the band mass anisotropy or the dielectric tensor are varied, while the phase remains robust. In the n=1 Landau level, mass anisotropy drives transitions between incompressible liquids and compressible states with charge density wave ordering. In n>=2 Landau levels, mass anisotropy selects and enhances stripe ordering with compatible wave vectors at partial 1/3 and 1/2 fillings. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.5586v1.pdf"}
{"id": "1203.0112", "abstract": "  We investigate the no-boundary measure in the context of moduli stabilization. To this end, we first show that for exponential potentials, there are no classical histories once the slope exceeds a critical value. We also investigate the probability distributions given by the no-boundary wave function near maxima of the potential. These results are then applied to a simple model that compactifies 6D to 4D (HBSV model) with fluxes. We find that the no-boundary wave function effectively stabilizes the moduli of the model. Moreover, we find the a priori probability for the cosmological constant in this model. We find that a negative value is preferred, and a vanishing cosmological constant is not distinguished by the probability measure. We also discuss the application to the cosmic landscape. Our preliminary arguments indicate that the probability of obtaining anti de Sitter space is vastly greater than for de Sitter. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.0112v2.pdf"}
{"id": "1203.1001", "abstract": "  In this talk I discuss a recently developed \"Unfolded Quantization Framework\". It allows to introduce a Hamiltonian Second Quantization based on a Hopf algebra endowed with a coproduct satisfying, for the Hamiltonian, the physical requirement of being a primitive element. The scheme can be applied to theories deformed via a Drinfeld twist. I discuss in particular two cases: the abelian twist deformation of a rotationally invariant nonrelativistic Quantum Mechanics (the twist induces a standard noncommutativity) and the Jordanian twist of the harmonic oscillator. In the latter case the twist induces a Snyder non-commutativity for the space-coordinates, with a pseudo-Hermitian deformed Hamiltonian. The \"Unfolded Quantization Framework\" unambiguously fixes the non-additive effective interactions in the multi-particle sector of the deformed quantum theory. The statistics of the particles is preserved even in the presence of a deformation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.1001v1.pdf"}
{"id": "1203.3629", "abstract": "  Much attention has been focused on ways of rendering graphene semiconducting. We study periodically gated graphene in a tight-binding model and find that, contrary to predictions based on the Dirac equation, it is possible to open a band gap at the Fermi level using electrostatic gating of graphene. However, comparing to other methods of periodically modulating graphene, namely perforated graphene structures, we find that the resulting band gap is significantly smaller. We discuss the intricate dependence of the band gap on the magnitude of the gate potential as well as the exact geometry of the edge of the gate region. The role of the overlap of the eigenstates with the gate region is elucidated. Considering more realistic gate potentials, we find that introducing smoothing in the potential distribution, even over a range of little more than a single carbon atom, reduces the attainable band gap significantly. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.3629v1.pdf"}
{"id": "1203.4009", "abstract": "  This paper is an overview of Image Processing and Analysis using Scilab, a free prototyping environment for numerical calculations similar to Matlab. We demonstrate the capabilities of SIP – the Scilab Image Processing Toolbox – which extends Scilab with many functions to read and write images in over 100 major file formats, including PNG, JPEG, BMP, and TIFF. It also provides routines for image filtering, edge detection, blurring, segmentation, shape analysis, and image recognition. Basic directions to install Scilab and SIP are given, and also a mini-tutorial on Scilab. Three practical examples of image analysis are presented, in increasing degrees of complexity, showing how advanced image analysis techniques seems uncomplicated in this environment. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.4009v1.pdf"}
{"id": "1203.5552", "abstract": "  We consider a theory of gravity with a hidden extra-dimension and metric-dependent torsion. A set of physically motivated constraints are imposed on the geometry so that the torsion stays confined to the extra-dimension and the extra-dimension stays hidden at the level of four dimensional geodesic motion. At the kinematic level, the theory maps on to General Relativity, but the dynamical field equations that follow from the action principle deviate markedly from the standard Einstein equations. We study static spherically symmetric vacuum solutions and homogeneous-isotropic cosmological solutions that emerge from the field equations. In both cases, we find solutions of significant physical interest. Most notably, we find positive mass solutions with naked singularity that match the well known Schwarzschild solution at large distances but lack an event horizon. In the cosmological context, we find oscillatory scenario in contrast to the inevitable, singular big bang of the standard cosmology. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.5552v2.pdf"}
{"id": "1203.6460", "abstract": "  In this paper, an improved quasi-particle model is presented. Unlike the previous approach of establishing quasi-particle model, we introduce a classical background field (it is allowed to depend on the temperature) to deal with the infinity of thermal vacuum energy which exists in previous quasi-particle models. After taking into account the effect of this classical background field, the partition function of quasi-particle system can be made well-defined. Based on this and following the standard ensemble theory, we construct a thermodynamically consistent quasi-particle model without the need of any reformulation of statistical mechanics or thermodynamical consistency relation. As an application of our model, we employ it to the case of (2+1) flavor QGP at zero chemical potential and finite temperature and obtain a good fit to the recent lattice simulation results of S. Borsanyi et al. A comparison of the result of our model with early calculations using other models is also presented. It is shown that our method is general and can be generalized to the case where the effective mass depends not only on the temperature but also on the chemical potential. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.6460v1.pdf"}
{"id": "1204.0426", "abstract": "  We investigate quotation and transaction activities in the foreign exchange market for every week during the period of June 2007 to December 2010. A scaling relationship between the mean values of number of quotations (or number of transactions) for various currency pairs and the corresponding standard deviations holds for a majority of the weeks. However, the scaling breaks in some time intervals, which is related to the emergence of market shocks. There is a monotonous relationship between values of scaling indices and global averages of currency pair cross-correlations when both quantities are observed for various window lengths Δ t. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.0426v1.pdf"}
{"id": "1204.0658", "abstract": "  We study the amplification of magnetic fields during the formation of primordial halos. The turbulence generated by gravitational infall motions during the formation of the first stars and galaxies can amplify magnetic fields very efficiently and on short timescales up to dynamically significant values. Using the Kazantsev theory, which describes the so-called small-scale dynamo - a magnetohydrodynamical process converting kinetic energy from turbulence into magnetic energy - we can then calculate the growth rate of the small-scale magnetic field. Our calculations are based on a detailed chemical network and we include non-ideal magnetohydrodynamical effects such as ambipolar diffusion and Ohmic dissipation. We follow the evolution of the magnetic field up to larger scales until saturation occurs on the Jeans scale. Assuming a weak magnetic seed field generated by the Biermann battery process, both Burgers and Kolmogorov turbulence lead to saturation within a rather small density range. Such fields are likely to become relevant after the formation of a protostellar disk and, thus, could influence the formation of the first stars and galaxies in the Universe. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.0658v2.pdf"}
{"id": "1204.0977", "abstract": "  The phase of the rotating order parameter in rotating antiferromagnetism is calculated using a combination of mean-field theory and Heisenberg equation. This phase shows a linear time dependence, which allows us to interpret rotating antiferromagnetism as a synchronized Larmor-like precession of all the spins in the system or as an unusual q=(π,π) spin-wave around a zero local magnetization. We discuss implications for the pseudogap state of high-T_C superconducting materials. Rotating antiferromagnetism has been proposed to model the pseudogap state in these materials. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.0977v1.pdf"}
{"id": "1204.1117", "abstract": "  In this paper we introduce an alternative renormalization program for systems with non-perturbative conditions. The non-perturbative conditions that we concentrate on in this paper are confined to be either the presence of non-trivial boundary conditions or non-perturbative background fields. We show that these non-perturbative conditions have profound effects on all physical properties of the system and our renormalization program is consistent with these conditions. We formulate the general renormalization program in the configuration space. The differences between the free space renormalization program and ours manifest themselves in the counter-terms as well, which we shall elucidate. The general expressions that we obtain for the counter-terms reduce to the standard results in the free space cases. We show that the differences between these divergent counter-terms are extremely small. Moreover we argue that the position dependences induced on the parameters of the renormalized Lagrangian via the loop corrections, however small, are direct and natural consequences of the non-perturbative position dependent conditions imposed on the system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.1117v2.pdf"}
{"id": "1204.1235", "abstract": "  With the aim of locating the origin of discrepancy between experimental and computer simulation results on bulk viscosity of liquid argon, a molecular dynamic simulation of argon interacting via ab initio pair potential and triple-dipole three-body potential has been undertaken. Bulk viscosity, obtained using Green-Kubo formula, is different from the values obtained from modeling argon using Lennard-Jones potential, the former being closer to the experimental data. The conclusion is made that many-body inter-atomic interaction plays a significant role in formation of bulk viscosity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.1235v1.pdf"}
{"id": "1204.2045", "abstract": "  Here we report on observations of the radio magnetar PSR J1622-4950 at frequencies from 1.4 to 17 GHz. We show that although its flux density is varying up to a factor of  10 within a few days, it has on average decreased by a factor of 2 over the last 700 days. At the same time, timing analysis indicates a trend of decreasing spin-down rate over our entire data set, again of about a factor of 2 over 700 days, but also an erratic variability in the spin-down rate within this time span. Integrated pulse profiles are often close to 100 per cent linearly polarized, but large variations in both the profile shape and fractional polarization are regularly observed. Furthermore, the behaviour of the position angle of the linear polarization is very complex - offsets in both the absolute position angle and the phase of the position angle sweep are often seen and the occasional presence of orthogonal mode jumps further complicates the picture. However, model fitting indicates that the magnetic and rotation axes are close to aligned. Finally, a single pulse analysis has been carried out at four observing frequencies, demonstrating that the wide pulse profile is built up of narrow spikes of emission, with widths that scale inversely with observing frequency. All three of the known radio magnetars seem to have similar characteristics, with highly polarized emission, time-variable flux density and pulse profiles, and with spectral indices close to zero. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.2045v1.pdf"}
{"id": "1204.3483", "abstract": "  Wolf-Rayet (WR) stars are the evolved descendants of massive O-type stars and are considered to be progenitor candidates for Type Ib/c core-collapse supernovae (SNe). Recent results of our HST/WFC3 survey of Wolf-Rayet stars in M101 are summarised based on the detection efficiency of narrow-band optical imaging compared to broad-band methods. Weshow that on average of 42", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.3483v1.pdf"}
{"id": "1204.4048", "abstract": "  We propose the simplest model of teleparallel dark energy with purely a non-minimal coupling to gravity but no self-potential, a single model possessing various interesting features: simplicity, self-potential-free, the guaranteed late-time cosmic acceleration driven by the non-minimal coupling to gravity, tracker behavior of the dark energy equation of state at earlier times, a crossing of the phantom divide at a late time, and the existence of a finite-time future singularity. We find the analytic solutions of the dark-energy scalar field respectively in the radiation, matter, and dark energy dominated eras, thereby revealing the above features. We further illustrate possible cosmic evolution patterns and present the observational constraint of this model obtained by numerical analysis and data fitting. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.4048v2.pdf"}
{"id": "1204.4110", "abstract": "  Gamma-Ray Bursts are likely associated with a catastrophic energy release in stellar mass objects. Electromagnetic observations provide important, but indirect information on the progenitor. On the other hand, gravitational waves emitted from the central source, carry direct information on its nature. In this context, I give an overview of the multi-messenger study of gamma-ray bursts that can be carried out by using electromagnetic and gravitational wave observations. I also underline the importance of joint electromagnetic and gravitational wave searches, in the absence of a gamma-ray trigger. Finally, I discuss how multi-messenger observations may probe alternative gamma-ray burst progenitor models, such as the magnetar scenario. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.4110v2.pdf"}
{"id": "1204.4486", "abstract": "  We present arcsecond resolution 1.4mm observations of the high mass star forming region, Sharpless 2-157, that reveal the cool dust associated with the first stages of star formation. These data are compared with archival images at optical, infrared, and radio wavelengths, and complemented with new arcsecond resolution mid-infrared data. We identify a dusty young HII region, numerous infrared sources within the cluster envelope, and four starless condensations. Three of the cores lie in a line to the south of the cluster peak, but the most massive one is right at the center and associated with a jumble of bright radio and infrared sources. This presents an interesting juxtaposition of high and low mass star formation within the same cluster which we compare with similar observations of other high mass star forming regions and discuss in the context of cluster formation theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.4486v1.pdf"}
{"id": "1204.4697", "abstract": "  We explore correlations of inhomogeneous local density of states (LDoS) for impure superconductors with different symmetries of the order parameter (s-wave and d-wave) and different types of scatterers (elastic and magnetic impurities). It turns out that the LDoS correlation function of superconductor always slowly decreases with distance up to the phase-breaking length l_ϕ and its long-range spatial behavior is determined only by the dimensionality, as in normal metals. On the other hand, the energy dependence of this correlation function is sensitive to symmetry of the order parameter and nature of scatterers. Only in the simplest case of s-wave superconductor with elastic scatterers the inhomogeneous LDoS is directly connected to the corresponding characteristics of normal metal. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.4697v3.pdf"}
{"id": "1205.2689", "abstract": "  It is shown that a chiral SU(2) model can break Lorentz symmetry spontaneously at the Lagrangian level when gauge bosons become massive. This model seems to propose the principles and conceptual foundations leading to a unified picture of fermions, and may reduce the standard theory to a far simpler form. The model suggests describing leptons and quarks as quasi-excitations, while electromagnetic and strong interactions as secondary interactions mediated by Nambu-Goldstone bosons originating from spontaneous violations of global SU(2) and rotational symmetries. Both the possibility of observing Lorentz-violating phenomena and their magnitudes are discussed. The model also provides an alternative scenario for baryon and lepton asymmetries of the Universe. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.2689v4.pdf"}
{"id": "1205.4355", "abstract": "  During 2003 and 2004 the Anomalous X-Ray Pulsar XTE J1810-197 went through a series of four bursts. The spectrum in the tail of one of these bursts shows a strong, significant emission feature  13 keV, thereby encoding a wealth of information about the environment surrounding this object. In this paper we analyse this emission feature considering both cyclotron and atomic emission processes and weigh our findings against three leading AXP models: the Magnetar model, Fall-back disk model and the Quark nova model. We find that atomic emission from Rubidium within a Keplerian ring (∼15 km from a compact object of ∼ 2M_⊙) is the most consistent scenario with the observations, supporting the Quark nova model. Cyclotron emission from an atmosphere a few hundred meters thick also fits the feature well, but is ruled out on account of its positional coincidence in three separate AXP sources. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.4355v1.pdf"}
{"id": "1205.6167", "abstract": "  In this work, a goodness-of-fit test for the null hypothesis of a functional linear model with scalar response is proposed. The test is based on a generalization to the functional framework of a previous one, designed for the goodness-of-fit of regression models with multivariate covariates using random projections. The test statistic is easy to compute using geometrical and matrix arguments, and simple to calibrate in its distribution by a wild bootstrap on the residuals. The finite sample properties of the test are illustrated by a simulation study for several types of basis and under different alternatives. Finally, the test is applied to two datasets for checking the assumption of the functional linear model and a graphical tool is introduced. Supplementary materials are available online. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.6167v7.pdf"}
{"id": "1205.6337", "abstract": "  Imagine that you have several sets of two coupled qubits, but you do not know the parameters of their Hamitonians. How to determine these without resorting to the usual spectroscopy approach to the problem? Based on numerical modeling, we show that all the parameters of a system of two coupled qubits can be determined by applying to it an external classical noise and analysing the Fourier spectrum of the elements of the system's density matrix. In particular, the interlevel spacings as well as the strength and sign of qubit-qubit coupling can be determined this way. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.6337v1.pdf"}
{"id": "1205.6556", "abstract": "  We study the asymptotic behavior of a class of methods for sufficient dimension reduction in high-dimension regressions, as the sample size and number of predictors grow in various alignments. It is demonstrated that these methods are consistent in a variety of settings, particularly in abundant regressions where most predictors contribute some information on the response, and oracle rates are possible. Simulation results are presented to support the theoretical conclusion. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1205/1205.6556v1.pdf"}
{"id": "1206.0024", "abstract": "  We present a method to quantify quantum correlations in arbitrary systems of indistinguishable fermions using witness operators. The method associates the problem of finding the optimal entan- glement witness of a state with a class of problems known as semidefinite programs (SDPs), which can be solved efficiently with arbitrary accuracy. Based on these optimal witnesses, we introduce a measure of quantum correlations which has an interpretation analogous to the Generalized Robust- ness of entanglement. We also extend the notion of quantum discord to the case of indistinguishable fermions, and propose a geometric quantifier, which is compared to our entanglement measure. Our numerical results show a remarkable equivalence between the proposed Generalized Robustness and the Schliemann concurrence, which are equal for pure states. For mixed states, the Schliemann con- currence presents itself as an upper bound for the Generalized Robustness. The quantum discord is also found to be an upper bound for the entanglement. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1206/1206.0024v1.pdf"}
{"id": "1206.0516", "abstract": "  In order to enhance the radiation power in terahertz band based on the intrinsic Josephson junctions of Bi_2Sr_2CaCu_2O_8+δ single crystal, we investigate a long cylindrical sample embedded in a dielectric material. Tuning the dielectric constant, the radiation power has a maximum which is achieved when it equals the dissipation caused by Josephson plasma. This yields the optimal dielectric constant of wrapping material in terms of the properties of BSCCO single crystal. The maximal radiation power is found proportional to the product of the typical superconducting current squared and the typical normal resistance, or the gap energy squared divided by the typical normal resistance, which offers a guideline for choosing superconductor as a source of strong radiation. By introducing an anti-reflection layer, we can build a compact device with the BSCCO cylinder and two wrapping dielectric layers with finite thicknesses. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1206/1206.0516v1.pdf"}
{"id": "1206.0775", "abstract": "  Detailed physisorption data from experiment for the H_2 molecule on low-index Cu surfaces challenge theory. Recently, density-functional theory (DFT) has been developed to account for nonlocal correlation effects, including van der Waals (dispersion) forces. We show that the functional vdW-DF2 gives a potential-energy curve, potential-well energy levels, and difference in lateral corrugation promisingly close to the results obtained by resonant elastic backscattering-diffraction experiments. The backscattering barrier is found selective for choice of exchange-functional approximation. Further, the DFT-D3 and TS-vdW corrections to traditional DFT formulations are also benchmarked, and deviations are analyzed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1206/1206.0775v1.pdf"}
{"id": "1206.3896", "abstract": "  We show that the plasmon spectrum of an ordinary two-dimensional electron gas (2DEG) hosted in a GaAs heterostructure is significantly modified when a graphene sheet is placed on the surface of the semiconductor in close proximity to the 2DEG. Long-range Coulomb interactions between massive electrons and massless Dirac fermions lead to a new set of optical and acoustic intra-subband plasmons. Here we compute the dispersion of these coupled modes within the Random Phase Approximation, providing analytical expressions in the long-wavelength limit that shed light on their dependence on the Dirac velocity and Dirac-fermion density. We also evaluate the resistivity in a Coulomb-drag transport setup. These Dirac/Schroedinger hybrid electron systems are experimentally feasible and open new research opportunities for fundamental studies of electron-electron interaction effects in two spatial dimensions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1206/1206.3896v1.pdf"}
{"id": "1206.6069", "abstract": "  The effects of finite temperature in transport through nanoscopic systems exhibiting uniaxial magnetic anisotropy D, such as molecular magnets, adatoms, or quantum dots side-coupled to a large spin are analyzed in the Kondo regime. The linear-response conductance is calculated by means of the full density-matrix numerical renormalization group method as a function of temperature T, magnetic anisotropy D, and exchange coupling J between the molecule's core spin and the orbital level. It is shown that such system displays a two-stage Kondo effect as a function of temperature and a quantum phase transition as a function of the exchange coupling J. Moreover, additional peaks are found in the linear conductance for temperatures of the order of T∼|J| and T. It is also shown that the conductance variation with T remarkably depends on the sign of the exchange coupling J. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1206/1206.6069v2.pdf"}
{"id": "1207.1127", "abstract": "  The compression or expansion of a magnetic field that is initially potential is considered. It was recently suggested by Janse     Low [2009, ApJ, 690, 1089] that, following the volumetric deformation, the relevant lowest energy state for the magnetic field is another potential magnetic field that in general contains tangential discontinuities (current sheets). Here we examine this scenario directly using a numerical relaxation method that exactly preserves the topology of the magnetic field. It is found that of the magnetic fields discussed by Janse     Low, only those containing magnetic null points develop current singularities during an ideal relaxation, while the magnetic fields without null points relax toward smooth force-free equilibria with finite non-zero current. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1207/1207.1127v1.pdf"}
{"id": "1207.1603", "abstract": "  Shocks driven by Coronal Mass Ejections (CMEs) are primary agents of space weather. They can accelerate particles to high energies and can compress the magnetosphere thus setting in motion geomagnetic storms. For many years, these shocks were studied only in-situ when they crossed over spacecraft or remotely through their radio emission spectra. Neither of these two methods provides information on the spatial structure of the shock nor on its relationship to its driver, the CME. In the last decade, we have been able to not only image shocks with coronagraphs but also measure their properties remotely through the use of spectroscopic and image analysis methods. Thanks to instrumentation on STEREO and SOHO we can now image shocks (and waves) from the low corona, through the inner heliosphere, to Earth. Here, we review the progress made in imaging and analyzing CME-driven shocks and show that joint coronagraphic and spectrscopic observations are our best means to understand shock physics close to the Sun. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1207/1207.1603v1.pdf"}
{"id": "1207.3589", "abstract": "  Superfluid turbulence consisting of quantized vortices is called quantum turbulence (QT). Quantum turbulence and quantized vortices were discovered in superfluid ^4He about 50 years ago, but innovation has occurred recently in this field. One is in the field of superfluid helium. Statistical quantities such as energy spectra and probability distribution function of the velocity field have been accessible both experimentally and numerically. Visualization technique has developed and succeeded in the direct visualization of quantized vortices. The other innovation is in the field of atomic Bose-Einstein condensation. The modern optical technique has enabled us to control and visualize directly the condensate and quantized vortices. Various kinds of hydrodynamic instability have been revealed. Even QT is realized experimentally. This article describes such recent developments as well as the motivation of studying QT. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1207/1207.3589v1.pdf"}
{"id": "1207.5386", "abstract": "  There exists, in general, a convex set of quantum state estimators that maximize the likelihood for informationally incomplete data. We propose an estimation scheme, catered to measurement data of this kind, to search for the exact maximum-likelihood-maximum-entropy estimator using semidefinite programming and a standard multi-dimensional function optimization routine. This scheme can be used to infer the expectation values of a set of entanglement witnesses that can be used to verify the entanglement of the unknown quantum state for composite systems. Next, we establish an alternative numerical scheme that is more computationally robust for the sole purpose of maximizing the likelihood and entropy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1207/1207.5386v1.pdf"}
{"id": "1208.0426", "abstract": "  The transverse bunch spectrum and the transverse decoherence/recoherence following an initial bunch offset are important phenomena in synchrotrons and storage rings, and are widely used for beam and lattice measurements. Incoherent shifts of the particles betatron frequency and of the synchrotron frequency modify the transverse spectrum and the bunch decoherence. In this study we analyze the effects of transverse space charge and of the rf nonlinearity on the decoherence signals. The transverse bunch decoherence and the resulting coherent spectra are measured in the SIS18 synchrotron at GSI Darmstadt for different bunch parameters. Particle tracking simulations together with an analytical model are used to describe the modifications in the decoherence signals and in the coherent spectra due to space charge and the rf bucket nonlinearity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1208/1208.0426v1.pdf"}
{"id": "1208.0810", "abstract": "  Fermi-LAT spectra at high energies (HE, 0.1-100 GeV) are often extrapolated to very high energies (VHE, >100 GeV) and considered either a good estimate or an upper limit for the blazars intrinsic VHE spectrum. This assumption seems not well justified, neither theoretically nor observationally. Besides being often softer, observations do indicate that spectra at VHE could be also harder than at HE, even when adopting the limit of Gamma=1.5. Results based on such straightforward GeV-TeV extrapolations are in general not reliable, and should be considered with caution. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1208/1208.0810v1.pdf"}
{"id": "1208.0828", "abstract": "  Very recently, it was pointed out that there exists a population of gamma-ray sources without associations at other wavelengths which exhibit spectral features consistent with mono-energetic lines at energies of approximately 111 and 129 GeV. Given recent evidence of similar gamma-ray lines from the Inner Galaxy, it is tempting to interpret these unassociated sources as nearby dark matter subhalos, powered by ongoing annihilations. In this paper, we study the spectrum, luminosity, and angular distribution of these sources, with the intention of testing the hypothesis that they are, in fact, dark matter subhalos. We find that of the 12 sources containing at least one prospective line photon, only 2 exhibit an overall gamma-ray spectrum which is consistent with that predicted from dark matter annihilations (2FGL J2351.6-7558 and 2FGL J0555.9-4348). After discounting the 10 clearly non-dark matter sources, the statistical significance of the remaining two prospective line photons is negligible. That being said, we cannot rule out the possibility that either or both of these sources are dark matter subhalos; their overall luminosity and galactic latitude distribution are not inconsistent with a dark matter origin. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1208/1208.0828v1.pdf"}
{"id": "1208.1761", "abstract": "  The stability properties of a low density ultra relativistic pair beam produced in the intergalactic medium by multi-TeV gamma-ray photons from blazars are analyzed. The problem is relevant for probes of magnetic field in cosmic voids through gamma-ray observations. In addition, dissipation of such beams could affect considerably the thermal history of the intergalactic medium and structure formation. We use a Monte Carlo method to quantify the properties of the blazar induced electromagnetic shower, in particular the bulk Lorentz factor and the angular spread of the pair beam generated by the shower, as a function of distance from the blazar itself. We then use linear and nonlinear kinetic theory to study the stability of the pair beam against the growth of electrostatic plasma waves, employing the Monte Carlo results for our quantitative estimates. We find that the fastest growing mode, like any perturbation mode with even a very modest component perpendicular to the beam direction, cannot be described in the reactive regime. Due to the effect of non-linear Landau damping, which suppresses the growth of plasma oscillations, the beam relaxation timescale is found significantly longer than the inverse Compton loss time. Finally, density inhomogeneities associated with cosmic structure induce loss of resonance between the beam particles and plasma oscillations, strongly inhibiting their growth. We conclude that relativistic pair beams produced by blazars in the intergalactic medium are stable on timescales long compared to the electromagnetic cascade's. There appears to be little or no effect of pair-beams on the intergalactic medium. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1208/1208.1761v3.pdf"}
{"id": "1208.2485", "abstract": "  Recently, much attention has been given to double-peaked narrow emission-line galaxies, some of which are suggested to be related with merging galaxies. We make a systematic search to build the largest sample of these sources from Data Release 7 of Sloan Digital Sky Survey (SDSS DR7). With reasonable criteria of fluxes, full-width-half-maximum of emission lines and separations of the peaks, we select 3,030 double-peaked narrow emission-lines galaxies. In light of the existence of broad Balmer lines and the locations of the two components of double-peaked narrow emission lines distinguished by the Kauffmann et al. (2003) criteria in the Baldwin-Phillips-Terlevich (BPT) diagram, we find that there are 81 type I AGN, 837 double-type II AGN (2-type II), 708 galaxies with double star forming components (2-SF), 400 with mixed star forming and type II AGN components (type II + SF) and 1,004 unknown-type objects. As a by-product, a sample of galaxies (12,582) with asymmetric or top-flat profiles of emission lines is established. After inspecting the SDSS images of the two samples visually, we find 54 galaxies with dual cores. The present samples can be used to study the dynamics of merging galaxies, the triggering mechanism of black hole activity, the hierarchical growth of galaxies and dynamics of narrow line regions driven by outflows and rotating disk. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1208/1208.2485v1.pdf"}
{"id": "1208.3321", "abstract": "  Motivated by the latest effort to employ banded matrices to estimate a high-dimensional covariance Σ, we propose a test for Σ being banded with possible diverging bandwidth. The test is adaptive to the \"large p, small n\" situations without assuming a specific parametric distribution for the data. We also formulate a consistent estimator for the bandwidth of a banded high-dimensional covariance matrix. The properties of the test and the bandwidth estimator are investigated by theoretical evaluations and simulation studies, as well as an empirical analysis on a protein mass spectroscopy data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1208/1208.3321v1.pdf"}
{"id": "1208.5636", "abstract": "  We present recent developments on the role of the running coupling constant at the intersection of perturbative and nonperturbative QCD. A number of experiments show a smooth transition from small to large scales given by the four-momentum transfer in the reactions. This is at variance with perturbative QCD where the running coupling constant becomes infinite when the scale equals Λ_ QCD. Approaches using an effective coupling constant could help interpret the opposite trend of data as compared to standard perturbative QCD predictions. We give an overview of the role of the coupling constant in the procedure to match nonperturbative hadronic model to perturbative QCD and we propose an extraction of an effective coupling constant from inclusive electron proton scattering data at large Bjorken x. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1208/1208.5636v1.pdf"}
{"id": "1209.2891", "abstract": "  We explore a few-fermion mixture consisting of two components which are repulsively interacting and confined in a one-dimensional harmonic trap. Different scenarios of population imbalance ranging from the completely imbalanced case where the physics of a single impurity in the Fermi-sea is discussed to the partially imbalanced and equal population configurations are investigated. For the numerical calculations the multi-configurational time-dependent Hartree (MCTDH) method is employed, extending its application to few-fermion systems. Apart from numerical calculations we generalize our Ansatz for a correlated pair wave-function proposed in [1] for bosons to mixtures of fermions. From weak to strong coupling between the components the energies, the densities and the correlation properties of one-dimensional systems change vastly with an upper limit set by fermionization where for infinite repulsion all fermions can be mapped to identical ones. The numerical and analytical treatments are in good agreement with respect to the description of this crossover. We show that for equal populations each pair of different component atoms splits into two single peaks in the density while for partial imbalance additional peaks and plateaus arise for very strong interaction strengths. The case of a single impurity atom shows rich behaviour of the energy and density as we approach fermionization, and is directly connected to recent experiments [2-4]. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1209/1209.2891v1.pdf"}
{"id": "1209.3963", "abstract": "  Consider testing multiple hypotheses using tests that can only be evaluated by simulation, such as permutation tests or bootstrap tests. This article introduces MMCTest, a sequential algorithm which gives, with arbitrarily high probability, the same classification as a specific multiple testing procedure applied to ideal p-values. The method can be used with a class of multiple testing procedures which includes the Benjamini     Hochberg False Discovery Rate (FDR) procedure and the Bonferroni correction controlling the Familywise Error Rate. One of the key features of the algorithm is that it stops sampling for all the hypotheses which can already be decided as being rejected or non-rejected. MMCTest can be interrupted at any stage and then returns three sets of hypotheses: the rejected, the non-rejected and the undecided hypotheses. A simulation study motivated by actual biological data shows that MMCTest is usable in practice and that, despite the additional guarantee, it can be computationally more efficient than other methods. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1209/1209.3963v8.pdf"}
{"id": "1209.4335", "abstract": "  Nanoscale hydrogen particles in superfluid helium track the motions of quantized vortices. This provides a way to visualize turbulence in the superfluid. Here, we trace the evolution of the hydrogen from a gas to frozen particles migrating toward the cores of quantized vortices. Not only are the intervening processes interesting in their own right, but understanding them better leads to more revealing experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1209/1209.4335v1.pdf"}
{"id": "1209.6527", "abstract": "  In this paper, we present the next-to-leading order predictions for diphoton production in the ADD model, matched to the HERWIG parton shower using the MC@NLO formalism. A selection of the results is presented for d=2-6 extra dimensions, using generic cuts as well as analysis cuts mimicking the search strategies as pursued by the ATLAS and CMS experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1209/1209.6527v1.pdf"}
{"id": "1210.0319", "abstract": "  We have studied the three-particle decay of 12C, 9Be and 6Be resonances. These nuclei have been described as three-body systems by means of the complex scaled hyperspherical adiabatic expansion method. The short-distance part of the wave-function is responsible for the energies whereas the information related to the observable decay properties is contained at large distances, which must be computed accurately. As an illustration we show the results for the angular distribution of 9Be and 6Be resonances. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.0319v1.pdf"}
{"id": "1210.0343", "abstract": "  We prove that the bounded derived category of the surface S constructed by Barlow admits a length 11 exceptional sequence consisting of (explicit) line bundles. Moreover, we show that in a small neighbourhood of S in the moduli space of determinantal Barlow surfaces, the generic surface has a semiorthogonal decomposition of its derived category into a length 11 exceptional sequence of line bundles and a category with trivial Grothendieck group and Hochschild homology, called a phantom category. This is done using a deformation argument and the fact that the derived endomorphism algebra of the sequence is constant. Applying Kuznetsov's results on heights of exceptional sequences, we also show that the sequence on S itself is not full and its (left or right) orthogonal complement is also a phantom category. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.0343v1.pdf"}
{"id": "1210.0470", "abstract": "  Self-similar and semi-analytical solutions are found for the height-averaged equations govern the dynamical behavior of a polytropic, self-gravitating disk under the effects of winds, around the nascent object. In order to describe time evolution of the system, we adopt a radius dependent mass loss rate, then highlight its importance on both the traditional α and innovative β models of viscosity prescription. In agreement with some other studies, our solutions represent that Toomre parameter is less than one in most regions on the β-disk which indicate that in such disks gravitational instabilities can occur in various distances from the central accretor and so the β-disk model might provide a good explanation of how the planetary systems form. The purpose of the present work is twofold. First, examining the structure of disk with wind in comparison to no-wind solution; and second, to see if the adopted viscosity prescription affects significantly the dynamical behavior of the disk-wind system. We also considered the temperature distribution in our disk by a polytropic condition. The solutions imply that, under our boundary conditions, the radial velocity is larger for α-disks and increases as wind becomes stronger in both viscosity models. Also, we noticed that the disk thickness increases by amplifying the wind or adopting larger values for polytropic exponent γ. It also may globally decrease if one prescribe β-model for the viscosity. Moreover, in both viscosity models, surface density and mass accretion rate reduce as wind gets stronger or γ increases. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.0470v2.pdf"}
{"id": "1210.0941", "abstract": "  A new phenomenological technique for using constant amplitude loading data to predict fatigue life from a variable amplitude strain history is presented. A critical feature of this reversal-by-reversal model is that the damage accumulation is inherently non-linear. The damage for a reversal in the variable amplitude loading history is predicted by approximating that the accumulated damage comes from a constant amplitude loading that has the strain range of the particular variable amplitude reversal. A key feature of this approach is that overloads at the beginning of the strain history have a more substantial impact on the total lifetime than overloads applied toward the end of the cycle life. This technique effectively incorporates the strain history in the damage prediction and has the advantage over other methods in that there are no fitting parameters that require substantial experimental data. The model presented here is validated using experimental variable amplitude fatigue data for three different metals. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.0941v1.pdf"}
{"id": "1210.1309", "abstract": "  We study the melting transition in crystals of rare gas Ar, Xe, and Kr by the use of extensive Monte Carlo simulations with the Lennard-Jones potential. The parameters of this potential have been deduced by Bernardes in 1958 from experiments of rare gas in the gaseous phase. It is amazing that the parameters of such a popular potential were not fully tested so far. In order to carry out precise tests, we have written a high-performance Monte Carlo program which allows in particular to take into account correctly the periodic boundary conditions to reduce surface effects and to reduce CPU time. Using the Bernardes parameters, we find that the melting temperature of several rare gas is from 13 to 20", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.1309v1.pdf"}
{"id": "1210.2137", "abstract": "  Fragmentation functions (FFs) describe the formation of final state particles from a partonic initial state. Precise knowledge of these functions is a key ingredient in accessing quantities such as the nucleon spin structure in semi-inclusive deep-inelastic scattering and proton proton collisions. However, fragmentation functions can currently not be determined from first principles Quantum Chromodynamics and have to be extracted from experimental data. The Belle experiment at KEK, Japan, provides a large data sample for high precision measurements on e^+e^- annihilations allowing for first-time or more precise extractions of fragmentation functions. Analyses for extractions of spin-independent (unpolarized FFs) as well as spin-dependent fragmentation functions (interference FFs) at Belle are presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.2137v3.pdf"}
{"id": "1210.2413", "abstract": "  This work describes a new instrument optimized for a detection of the neutral hydrogen 21cm power spectrum between redshifts of 0.5-1.5: the Baryon Acoustic Oscillation Broadband and Broad-beam (BAOBAB) Array. BAOBAB will build on the efforts of a first generation of 21cm experiments which are targeting a detection of the signal from the Epoch of Reionization at z   10. At z   1, the emission from neutral hydrogen in self-shielded overdense halos also presents an accessible signal, since the dominant, synchrotron foreground emission is considerably fainter than at redshift 10. The principle science driver for these observations are Baryon Acoustic Oscillations in the matter power spectrum which have the potential to act as a standard ruler and constrain the nature of dark energy. BAOBAB will fully correlate dual-polarization antenna tiles over the 600-900MHz band with a frequency resolution of 300 kHz and a system temperature of 50K. The number of antennas will grow in staged deployments, and reconfigurations of the array will allow for both traditional imaging and high power spectrum sensitivity operations. We present calculations of the power spectrum sensitivity for various array sizes, with a 35-element array measuring the cosmic neutral hydrogen fraction as a function of redshift, and a 132-element system detecting the BAO features in the power spectrum, yielding a 1.8", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.2413v2.pdf"}
{"id": "1210.2721", "abstract": "  We examine the Velocity Distribution Function (VDF) in dark matter halos from Milky Way to cluster mass scales. We identify an empirical model for the VDF with a wider peak and a steeper tail than a Maxwell–Boltzmann distribution, and discuss physical explanations. We quantify sources of scatter in the VDF of cosmological halos and their implication for direct detection of dark matter. Given modern simulations and observations, we find that the most significant uncertainty in the VDF of the Milky Way arises from the unknown radial position of the solar system relative to the dark matter halo scale radius. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.2721v2.pdf"}
{"id": "1210.2955", "abstract": "  We consider the collection of uniformly discrete point sets in Euclidean space equipped with the vague topology. For a point set in this collection, we characterise minimality of an associated dynamical system by almost repetitivity of the point set. We also provide linear versions of almost repetitivity which lead to uniquely ergodic systems. Apart from linearly repetitive point sets, examples are given by periodic point sets with almost periodic modulations, and by point sets derived from primitive substitution tilings of finite local complexity with respect to the Euclidean group with dense tile orientations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.2955v2.pdf"}
{"id": "1210.3159", "abstract": "  We analyze the state space of a Bianchi-I universe with anisotropic sources. Here we consider an extended state space which includes null geodesics in this background. The evolution equations for all the state observables are derived. Dynamical systems approach is used to study the evolution of these equations. The asymptotic stable fixed points for all the evolution equations are found. We also check our analytic results with numerical analysis of these dynamical equations. The evolution of the state observables are studied both in cosmic time and using a dimensionless time variable. Then we repeat the same analysis with a more realistic scenario, adding the isotropic (dust like dark) matter and a cosmological constant (dark energy) to our anisotropic sources, to study their co-evolution. The universe now approaches a de Sitter space asymptotically dominated by the cosmological constant. The cosmic microwave background anisotropy maps due to shear are also generated in this scenario, assuming that the universe contains anisotropic matter along with the usual (dark) matter and vacuum (dark) energy since decoupling. We find that they contribute dominantly to the CMB quadrupole. We also constrain the current level of anisotropy and also search for any cosmic preferred axis present in the data. We use the Union 2 Supernovae data to this extent. An anisotropy axis close to the mirror symmetry axis seen in the cosmic microwave background data from Planck probe is found. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.3159v3.pdf"}
{"id": "1210.3177", "abstract": "  The jamming transition characterizes athermal systems of particles interacting via finite range repulsive potentials, and occurs on increasing the density when particles cannot avoid making contacts with those of their first coordination shell. We have recently shown [M. Pica Ciamarra and P. Sollich, arXiv:1209.3334] that the same systems are also characterized by a series of jamming crossovers. These occur at higher volume fractions as particles are forced to make contact with those of subsequent coordination shells. At finite temperature, the crossovers give rise to dynamic and thermodynamic density anomalies, including a diffusivity anomaly and a negative thermal expansion coefficient. Density anomalies may therefore be related to structural changes occurring at the jamming crossovers. Here we elucidate these structural changes, investigating the evolution of the structure and of the mechanical properties of a jammed system as its volume fraction varies from the jamming transition to and beyond the first jamming crossover. We show that the first jamming crossover occurs at a well defined volume fraction, and that it induces a rearrangement of the force network causing a softening of the system. It also causes qualitative changes in the normal mode density of states and the spatial properties of the normal mode vectors. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.3177v1.pdf"}
{"id": "1210.3592", "abstract": "  We show the effects of environmental evolution on Virgo cluster and field dwarf elliptical galaxies (dEs), presenting the first large-scale integral-field spectroscopic data for this galaxy class. The great variety of morphological, kinematic, and stellar population parameters seen in our data supports the claim that dEs are defunct dwarf spiral/irregular galaxies and points to a formation scenario that allows for a stochastic shaping of galaxy properties. We further investigate the properties of our sample by analyzing its kinematic and dynamical properties. We compare the level of rotational support of dEs and giant early-type galaxies and show that the properties of the former largely resemble those of giant fast-rotators. Based on our data, no trend exists between the level of rotational support in dEs and their location in the cluster. However, a tentative trend is seen in dark matter fraction: it increases for larger Virgocentric distances. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.3592v1.pdf"}
{"id": "1210.5350", "abstract": "  We report on the measurement of the magnetic susceptibility and of ESR transitions in the garnet substance Tb_3Ga_5O_12 (TGG). The results are compared with a calculation in the framework of crystal field theory for the orthorhombic surroundings of the six inequivalent Tb ions of TGG. We also present a calculation of the magnetization for the three main crystal directions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.5350v1.pdf"}
{"id": "1210.5937", "abstract": "  A construction of node-less atomic orbitals and energy-dependent, node-reduced partial waves is presented, that contains the full information of the atomic eigenstates and that allows to represent the scattering properties in a transparent manner. By inverting the defining Schrödinger equation, the Pauli repulsion by the core electrons can be represented as effective potential. This construction also provides a description of the Pauli repulsion by an environment. Furthermore, the representation leads to a new systematic scheme for a projector augmentation. The relation to Slater orbitals is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.5937v1.pdf"}
{"id": "1210.7446", "abstract": "  We propose a conceptually novel method of reconstructing the topology of dynamical networks. By examining the correlation between the variable of one node and the derivative of another node, we derive a simple matrix equation yielding the network adjacency matrix. Our assumptions are the possession of time series describing the network dynamics, and the precise knowledge of the interaction functions. Our method involves a tunable parameter, allowing for the reconstruction precision to be optimized within the constraints of given dynamical data. The method is illustrated on a simple example, and the dependence of the reconstruction precision on the dynamical properties of time series is discussed. Our theory is in principle applicable to any weighted or directed network whose internal interaction functions are known. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.7446v2.pdf"}
{"id": "1211.0102", "abstract": "  It is known that the Z and atoll sources are two typical types of neutron-star sources in low mass X-ray binaries (LMXBs), which present very different Q-ν relations of lower kHz QPOs. We propose that the Z and atoll sources are two different phases in the evolutionary track of neutron star in LMXBs, instead of two types of distinct sources. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.0102v1.pdf"}
{"id": "1211.1504", "abstract": "  A highly efficient and simple to implement Monte Carlo algorithm is proposed for the evaluation of the Renyi entanglement entropy(REE) of quantum dimer model(QDM) at the Rokhsar-Kivelson(R-K) point. It makes possible the evaluation of REE at the R-K point to the thermodynamic limit for a general QDM. We apply the algorithm to QDM on both triangular and square lattice as demonstrations and find the REE on both lattices follow perfect linear scaling in the thermodynamic limit, apart from an even-odd oscillation in the latter case. We also evaluate the topological entanglement entropy(TEE) on both lattices with a subtraction procedure. While the expected TEE of ln2 is clearly demonstrated for QDM on triangular lattice, a strong oscillation of the result is found for QDM on square lattice, which implies the relevance of boundary perturbation in such a critical system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.1504v1.pdf"}
{"id": "1211.1801", "abstract": "  In a D-dimensional maximally symmetric spacetime we simplify the massless Dirac equation to two decoupled wavelike equations with effective potentials. Furthermore in D-dimensional Schwarzschild and Schwarzschild de Sitter black holes we note that for the massless Dirac field moving in the region exterior to the event horizon at least one of the effective potentials is not positive definite. Therefore the classical stability of these black holes against this field is not guaranteed. Here with the help of the S-deformation method, we state their classical stability against the massless Dirac field, extend these results to maximally symmetric black holes, and comment on the applicability of our results to establish the stability with respect to other classical fields. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.1801v1.pdf"}
{"id": "1211.1950", "abstract": "  We demonstrate a fully cryogenic microwave feedback network composed of modular superconducting devices connected by transmission lines and designed to control a mechanical oscillator coupled to one of the devices. The network features an electromechanical device and a tunable controller that coherently receives, processes and feeds back continuous microwave signals that modify the dynamics and readout of the mechanical state. While previous electromechanical systems represent some compromise between efficient control and efficient readout of the mechanical state, as set by the electromagnetic decay rate, the tunable controller produces a closed-loop network that can be dynamically and continuously tuned between both extremes much faster than the mechanical response time. We demonstrate that the microwave decay rate may be modulated by at least a factor of 10 at a rate greater than 10^4 times the mechanical response rate. The system is easy to build and suggests that some useful functions may arise most naturally at the network-level of modular, quantum electromagnetic devices. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.1950v3.pdf"}
{"id": "1211.2183", "abstract": "  Rotating Radio Transients (RRATs) are a class of pulsars characterized by sporadic bursts of radio emission, which make them difficult to detect in typical periodicity-based pulsar searches. Using newly developed post-processing techniques for automatically identifying single bright astrophysical pulses, such as those emitted from RRATs, we have discovered approximately 30 new RRAT candidates in data from the Green Bank Telescope 350 MHz drift-scan survey. A total of 6 of these have already been confirmed and the remainder look extremely promising. Here we describe these techniques and present the most recent results on these new RRAT candidates. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.2183v1.pdf"}
{"id": "1211.2355", "abstract": "  Fundamentals of energy density functional in nuclear physics are presented. Much attention is paid to a mathematically rigorous treatment of deriving the energy density functional. The specific features of the density functional used in studying many-nucleon systems, which is quite different from that used in many-electron systems, are also shown. The intended audience are physicists, chemists and mathematicians. In particular those who will start to study the density functional theory are intended. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.2355v4.pdf"}
{"id": "1211.4910", "abstract": "  Understanding the rich dynamics of open quantum systems is of fundamental interest to quantum control and quantum information processing. By considering an open system of many identical two-level atoms interacting with a common bath, we show that effects of system-bath correlations are amplified in a many-body system via the generation of a short time scale inversely proportional to the number of atoms. Effects of system-bath correlations are therefore considerable even when each individual atom interacts with the bath weakly. We further show that correlation-induced dynamical effects may still be suppressed via the dynamical decoupling approach, but they present a challenge for quantum state protection as the number of atom increases. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.4910v1.pdf"}
{"id": "1211.5324", "abstract": "  Inhomogeneous charge distributions have important repercussions on electrostatic interactions in systems of charged particles but are often difficult to examine theoretically. We investigate how electrostatic interactions are influenced by patchy charge distributions exhibiting certain point group symmetries. We derive a general form of the electrostatic interaction energy of two permeable, arbitrarily charged spherical shells in the Debye-Hückel approximation and apply it to the case of particles with icosahedral, octahedral, and tetrahedral inhomogeneous charge distributions. We analyze in detail how charge distribution symmetry modifies the interaction energy and find that local charge inhomogeneities reduce the repulsion of two overall equally charged particles, while sufficient orientational variation in the charge distribution can turn the minimum interaction energy into an attraction. Additionally we show that larger patches and thus lower symmetries and wave numbers result in bigger attraction given the same variation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.5324v2.pdf"}
{"id": "1211.5379", "abstract": "  Using 5 GHz radio luminosity at light-curve maximum as a proxy for jet power and black-hole spin measurements obtained via the continuum-fitting method, Narayan     McClintock (2012) presented the first direct evidence for a relationship between jet power and black hole spin for four transient black-hole binaries. We test and confirm their empirical relationship using a fifth source, H1743-322, whose spin was recently measured. We show that this relationship is consistent with Fe-line spin measurements provided that the black hole spin axis is assumed to be aligned with the binary angular momentum axis. We also show that, during a major outburst of a black hole transient, the system reasonably approximates an X-ray standard candle. We further show, using the standard synchrotron bubble model, that the radio luminosity at light-curve maximum is a good proxy for jet kinetic energy. Thus, the observed tight correlation between radio power and black hole spin indicates a strong underlying link between mechanical jet power and black hole spin. Using the fitted correlation between radio power and spin for the above five calibration sources, we predict the spins of six other black holes in X-ray/radio transient systems with low-mass companions. Remarkably, these predicted spins are all relatively low, especially when compared to the high measured spins of black holes in persistent, wind-fed systems with massive companions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.5379v2.pdf"}
{"id": "1211.5869", "abstract": "  Dynamics of a superfluid flow past an obstacle are investigated by solving the Gross-Pitaevskii equation numerically. For an appropriate velocity and size of the obstacle, quantized vortices are periodically generated in the wake, which form a Benard-von Karman vortex street. It is found that vibration of an obstacle modulates the vortex street breaking a symmetry. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.5869v2.pdf"}
{"id": "1212.0218", "abstract": "  In the present work we carry out a study of the high energy cosmic rays mass identification capabilities of a hybrid detector employing both fluorescence telescopes and particle detectors at ground using simulated data. It involves the analysis of extensive showers with zenith angles above 60 degrees making use of the joint distribution of the depth of maximum and muon size at ground level as mass discriminating parameters. The correlation and sensitivity to the primary mass are investigated. Two different techniques - clustering algorithms and neural networks - are adopted to classify the mass identity on an event-by-event basis. Typical results for the achieved performance of identification are reported and discussed. The analysis can be extended in a very straightforward way to vertical showers or can be complemented with additional discriminating observables coming from different types of detectors. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1212/1212.0218v2.pdf"}
{"id": "1212.4323", "abstract": "  Bound and resonance states of quantum dots play a significant role in photo-absorption processes. In this work, we analyze a cylindrical quantum dot, its spectrum and, in particular, the behaviour of the lowest resonance state when a magnetic field is applied along the symmetry axis of the cylinder. To obtain the energy and width of the resonance we use the complex rotation method. As it is expected the structure of the spectrum is strongly influenced by the Landau levels associated to the magnetic field. We show how this structure affects the behaviour of the resonance state and that the binding of the resonance has a clear interpretation in terms of the Landau levels and the probability of localization of the resonance state. The localization probability and the fidelity of the lowest energy state allows to identify two different physical regimes, a large field-small quantum dot radius regime and a small field-large quantum dot radius, where the binding of the resonance is dominated by the field strength or the potential well, respectively. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1212/1212.4323v2.pdf"}
{"id": "1301.1837", "abstract": "  Recently, different numerical studies of coarsening in disordered systems have shown the existence of a crossover from an initial, transient, power-law domain growth to a slower, presumably logarithmic, growth. However, due to the very slow dynamics and the long lasting transient regime, one is usually not able to fully enter the asymptotic regime when investigating the relaxation of these systems toward equilibrium. We here study two simple driven systems, the one-dimensional ABC model and a related domain model with simplified dynamics, that are known to exhibit anomalous slow relaxation where the asymptotic logarithmic growth regime is readily accessible. Studying two-times correlation and response functions, we focus on aging processes and dynamical scaling during logarithmic growth. Using the time-dependent growth length as the scaling variable, a simple aging picture emerges that is expected to also prevail in the asymptotic regime of disordered ferromagnets and spin glasses. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.1837v1.pdf"}
{"id": "1301.1867", "abstract": "  In this paper, we present the general governing equations of electrodynamics and continuum mechanics that need to be considered while mathematically modelling the behaviour of electromagnetic acoustic transducers (EMATs). We consider the existence of finite deformations for soft materials and the possibility of electric currents, temperature gradients, and internal heat generation due to dissipation. Starting with Maxwell's equations of electromagnetism and balance laws of nonlinear elasticity, we present the governing equations and boundary conditions in incremental form in order to solve wave propagation problems of boundary value type. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.1867v2.pdf"}
{"id": "1301.4358", "abstract": "  Exact inhomogeneous solutions of Einstein's equations have been used in the literature to build models reproducing the cosmological data without dark energy. However, owing to the degrees of freedom pertaining to these models, it is necessary to get rid of the degeneracy often exhibited by the problem of distinguishing between them and accelerating universe models. We give an overview of redshift drift in inhomogeneous cosmologies, and explain how it serves to this purpose. One class of models which fits the data is the Szekeres Swiss-cheese class where non-spherically symmetric voids exhibit a typical size of about 400 Mpc. We present our calculation of the redshift drift in this model, and compare it with the results obtained by other authors for alternate scenarios. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.4358v2.pdf"}
{"id": "1301.4439", "abstract": "  We propose a method to generate a source of spin-polarized cold atoms which are continuously extracted and guided from a magneto-optical trap using an atom-diode effect. We show that it is possible to create a pipe-like potential by overlapping two optical beams coupled with the two transitions of a three-level system in a ladder configuration. With alkali-metal atoms, and in particular with ^87Rb, a proper choice of transitions enables both the potential generation and optical pumping, thus polarizing the sample in a given Zeeman state. We extend the Dalibard and Cohen-Tannoudji dressed-atom model of radiative forces to the case of a three-level system. We derive expressions for the average force and the different sources of momentum diffusion in the resonant, non-perturbative regime. We show using numerical simulations that a significant fraction of the atoms initially loaded can be guided over several centimeters with output velocities of a few meters per second. This would produce a collimated continuous source of slow spin-polarized atoms suitable for atom interferometry. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.4439v3.pdf"}
{"id": "1301.4743", "abstract": "  We investigate the charmed baryon mass spectrum using the relativistic heavy quark action on 2+1 flavor PACS-CS configurations previously generated on 32^3 × 64 lattice. The dynamical up-down and strange quark masses are tuned to their physical values, reweighted from those employed in the configuration generation. At the physical point, the inverse lattice spacing determined from the Ω baryon mass gives a^-1=2.194(10) GeV, and thus the spatial extent becomes L = 32 a = 2.88(1) fm. Our results for the charmed baryon masses are consistent with experimental values, except for the mass of Ξ_cc, which has been measured by only one experimental group so far and has not been confirmed yet by others. In addition, we report values of other doubly and triply charmed baryon masses, which have never been measured experimentally. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.4743v2.pdf"}
{"id": "1301.5391", "abstract": "  Equipartition arguments provide an easy way to find a characteristic scale for the magnetic field from radio emission, by assuming the energy densities in cosmic rays and magnetic fields are the same. Yet most of the cosmic ray content in star-forming galaxies is in protons, which are invisible in radio emission. Therefore, the argument needs assumptions about the proton spectrum, typically that of a constant proton/electron ratio. In some environments, particularly starburst galaxies, the reasoning behind these assumptions does not necessarily hold: secondary pionic positrons and electrons may be responsible for most of the radio emission, and strong energy losses can alter the proton/electron ratio. We derive an equipartition expression that should work in a hadronic loss-dominated environment like starburst galaxies. Surprisingly, despite the radically different assumptions from the classical equipartition formula, numerically the results for starburst magnetic fields are similar. We explain this fortuitous coincidence using the energetics of secondary production and energy loss times. We show that these processes cause the proton/electron ratio to be  100 for GHz-emitting electrons in starbursts. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.5391v1.pdf"}
{"id": "1301.5808", "abstract": "  We review the performance of the PBEint GGA functional (Phys. Rev. B 2010, 82, 113104) recently proposed to improve the description of hybrid interfaces, and we introduce its one-parameter hybrid form (hPBEint). We consider different well established benchmarks for energetic and structural properties of molecular and solid-state systems as well as model systems and newly developed benchmark sets for dipole moments and metal-molecule interactions. We find that PBEint and hPBEint (with 16.67", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.5808v1.pdf"}
{"id": "1301.6292", "abstract": "  Europa's tenuous atmosphere results from sputtering of the surface. The trace element composition of its atmosphere is therefore related to the composition of Europa's surface. Magnesium salts are often invoked to explain Galileo Near Infrared Mapping Spectrometer spectra of Europa's surface, thus magnesium may be present in Europa's atmosphere. We have searched for magnesium emission in Hubble Space Telescope Faint Object Spectrograph archival spectra of Europa's atmosphere. Magnesium was not detected and we calculate an upper limit on the magnesium column abundance. This upper limit indicates that either Europa's surface is depleted in magnesium relative to sodium and potassium, or magnesium is not sputtered as efficiently resulting in a relative depletion in its atmosphere. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.6292v2.pdf"}
{"id": "1301.7012", "abstract": "  Despite the importance of the path integral, there have been relatively few attempts to look to the Lagrangian for a more realistic framework that might underlie quantum theory. While such realism is not available for the standard path integral or quantum field theory, a promising alternative is to only consider field histories for which the Lagrangian density is always zero. With this change, it appears possible to replace amplitudes with equally-weighted probabilities. This paper demonstrates a proof-of-principle for this approach, using a toy Lagrangian that corresponds to an arbitrary spin state. In this restricted framework one can derive both the Born rule and its limits of applicability. The fact that the Lagrangian obeys future boundary constraints also results in the first continuous, spacetime-based, hidden-variable description of a Bell-inequality-violating system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.7012v1.pdf"}
{"id": "1302.0339", "abstract": "  We present a detailed study to show the possibility of approaching the quantum ground-state of a hybrid optomechanical quantum device formed by a Bose-Einstein condensate (BEC) confined inside a high-finesse optical cavity with an oscillatory end mirror. Cooling is achieved using two experimentally realizable schemes: back-action cooling and cold damping quantum feedback cooling. In both the schemes, we found that increasing the two body atom-atom interaction brings the mechanical oscillator to its quantum ground state. It has been observed that back-action cooling is more effective in the good cavity limit while the cold damping cooling scheme is more relevant in the bad cavity limit. It is also shown that in the cold damping scheme, the device is more efficient in the presence of BEC than in the absence of BEC. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1302/1302.0339v1.pdf"}
{"id": "1302.1377", "abstract": "  The Degasperis-Procesi equation (DP) is one of several equations known to model important nonlinear effects such as wave breaking and shock creation. It is, however, a special property of the DP equation that these two effects can be studied in an explicit way with the help of the multipeakon ansatz. In essence this ansatz allows one to model wave breaking as a collision of hypothetical particles (peakons and antipeakons), called henceforth collectively multipeakons. It is shown that DP multipeakons have Painlevé property which implies a universal wave breaking behaviour, that multipeakons can collide only in pairs, and that there are no multiple collisions other than, possibly simultaneous, collisions of peakon-antipeakon pairs at different locations. Moreover, it is demonstrated that each peakon-antipeakon collision results in creation of a shock thus making possible a multi shock phenomenon. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1302/1302.1377v1.pdf"}
{"id": "1302.1585", "abstract": "  We report results from XMM-Newton and Chandra observations of the nearby (z = 0.067) giant radio galaxy 3C 35. We find evidence for an X-ray emitting gas belt, orthogonal to and lying between the lobes of 3C 35, which we interpret as fossil-group gas driven outwards by the expanding radio lobes. We also detect weak emission from a second, more extended group-type environment, as well as inverse-Compton X-ray emission from the radio lobes. The morphological structure of the radio lobes and gas belt point to co-evolution. Furthermore, the radio source is powerful enough to eject galaxy-scale gas out to distances of 100kpc, and the ages of the two features are comparable (tsynch 140Myr, tbelt 80 Myr). The destruction of 3C 35's atmosphere may offer clues as to how fossil systems are regulated: radio galaxies need to be of power comparable to 3C 35 to displace and regulate fossil-group gas. We discuss the implications of the gas belt in 3C 35 in terms of AGN fuelling and feedback. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1302/1302.1585v1.pdf"}
{"id": "1302.1776", "abstract": "  We have implemented highly stable and tunable frequency references using optical high finesse cavities which incorporate a piezo actuator. As piezo material we used ceramic PZT, crystalline quartz, or PZN-PT single crystals. Lasers locked to these cavities show a relative frequency stability better than 1 x 10^-14, which is most likely not limited by the piezo actuators. The piezo cavities can be electrically tuned over more than one free spectral range (> 1.5 GHz) with only a minor decrease in frequency stability. Furthermore, we present a novel cavity design, where the piezo actuator is prestressed between the cavity spacer components. This design features a hermetically sealable intra cavity volume suitable for, e.g., cavity enhanced spectroscopy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1302/1302.1776v1.pdf"}
{"id": "1302.2029", "abstract": "  The stability of nonvolatile thin liquid films and of sessile droplets is strongly affected by finite size effects. We analyze their stability within the framework of density functional theory using the sharp kink approximation, i.e., on the basis of an effective interface Hamiltonian. We show that finite size effects suppress spinodal dewetting of films because it is driven by a long-wavelength instability. Therefore nonvolatile films are stable if the substrate area is too small. Similarly, nonvolatile droplets connected to a wetting film become unstable if the substrate area is too large. This instability of a nonvolatile sessile droplet turns out to be equivalent to the instability of a volatile drop which can attain chemical equilibrium with its vapor. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1302/1302.2029v1.pdf"}
{"id": "1302.3823", "abstract": "  We address the issue of dephasing effects in flying polarization qubits propagating through optical fiber by using the method of dynamical decoupling. The control pulses are implemented with half waveplates suitably placed along the realistic lengths of the single mode optical fiber. The effects of the finite widths of the waveplates on the polarization rotation are modeled using tailored refractive index profiles inside the waveplates. We show that dynamical decoupling is effective in preserving the input qubit state with the fidelity close to one when the polarization qubit is subject to the random birefringent noise in the fiber, as well the rotational imperfections (flip-angle errors) due to the finite width of the waveplates. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1302/1302.3823v3.pdf"}
{"id": "1302.5041", "abstract": "  We review the magnetic form factor deduced by Delrieu from the Gorkov's equation for a Bardeen-Cooper-Schrieffer (BCS) type-II superconductor near its Bc2 phase boundary, i.e. when its magnetization is small. A numerical study of the form factor, field map, and field distribution follows. The characteristics of the transition from the low-temperature BCS to the high-temperature Ginzburg-Landau vortex lattices is studied. The exotic shape of the component field distribution and the form factor at low temperature and as a function of the external field intensity are discussed. Our numerical work should be helpful for the analysing of small angle neutron scattering and muon spin rotation vortex-lattice data recorded for BCS superconductors and maybe other superconductors in the clean limit. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1302/1302.5041v2.pdf"}
{"id": "1303.0592", "abstract": "  This paper investigates three open problems in random beamforming based communication systems: the scheduling policy with heterogeneous users, the closed form sum rate, and the randomness of multiuser diversity with selective feedback. By employing the cumulative distribution function based scheduling policy, we guarantee fairness among users as well as obtain multiuser diversity gain in the heterogeneous scenario. Under this scheduling framework, the individual sum rate, namely the average rate for a given user multiplied by the number of users, is of interest and analyzed under different feedback schemes. Firstly, under the full feedback scheme, we derive the closed form individual sum rate by employing a decomposition of the probability density function of the selected user's signal-to-interference-plus-noise ratio. This technique is employed to further obtain a closed form rate approximation with selective feedback in the spatial dimension. The analysis is also extended to random beamforming in a wideband OFDMA system with additional selective feedback in the spectral dimension wherein only the best beams for the best-L resource blocks are fed back. We utilize extreme value theory to examine the randomness of multiuser diversity incurred by selective feedback. Finally, by leveraging the tail equivalence method, the multiplicative effect of selective feedback and random observations is observed to establish the individual rate scaling. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1303/1303.0592v1.pdf"}
{"id": "1303.2296", "abstract": "  The vortex hopping motion in a type-II superconductor determines the current-carrying ability and consequently the application fields of the superconductor. However, it is not clear how the vortices hop between the different pinning regions in the superconductor. Here we proposed that there should be magnetic flux exchange between two contacting pinning regions. A system of differential equations was constructed to describe the flux exchange phenomenon. The qualitative analysis methods were used. The approximate numerical solutions and approximate analytical solutions of the system were obtained. The results show that the flux exchange reduces the internal field in a weak pinning region, but increases the internal field in a strong pinning region. Moreover, the flux exchange phenomenon is strongly influenced by the superconductor's geometrical size. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1303/1303.2296v2.pdf"}
{"id": "1303.3821", "abstract": "  We investigate the time dynamics of quantum correlations of the anisotropic Heisenberg model in a time-dependent magnetic field, in one-dimensional, ladder, and two-dimensional lattices. We find that quantum correlation measures in the entanglement-separability paradigm are ergodic in these systems irrespective of system parameters. However, information-theoretic quantum correlation measures can also be nonergodic, and exhibit a transition from nonergodic to ergodic behavior with the change of interaction strength in the direction of the magnetic field. We also observe that the transition point changes drastically as we go from one-dimensional and ladder lattices to the two-dimensional one. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1303/1303.3821v1.pdf"}
{"id": "1303.5792", "abstract": "  In this paper, we report all results obtained with a fiber scrambler on the Hamilton spectrograph at Lick Observatory. We demonstrate an improvement in the stability of the instrumental profile using this fiber scrambler. Additionally, we present data obtained with a double scrambler that further improves the stability of the instrument by a factor 2. These results show that errors related to the coupling between the telescope and the spectrograph are the dominant source of instrumental profile variability at Lick Observatory. In particular, we show a strong correlation between instrumental profile variations and hour angle, most likely due to pointing-dependent illumination of the spectrograph optics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1303/1303.5792v1.pdf"}
{"id": "1303.6176", "abstract": "  We present a study of the static and dynamical Casimir effects for a quantum field theory satisfying generalized Robin boundary condition, of a kind that arises naturally within the context of quantum circuits. Since those conditions may also be relevant to measurements of the dynamical Casimir effect, we evaluate their role in the concrete example of a real scalar field in 1+1 dimensions, a system which has a well-known mechanical analogue involving a loaded string. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1303/1303.6176v1.pdf"}
{"id": "1303.6248", "abstract": "  We performed a detailed analysis of extensive photometric observations of a sample of most active dwarf novae, that is SU UMa stars which are characterised by supercycle lengths shorter than 120 days. We found the observational evidence that supercycle lengths for these objects have been constantly increasing over the past decades, which indicates that their mean mass transfer rates have been decreasing during that time. This seems to be a common feature for this type of stars. We present numerical results in each case and estimate time scales of future development of these systems. This study is important in the context of evolution of dwarf novae stars and perhaps other cataclysmic variables. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1303/1303.6248v1.pdf"}
{"id": "1304.0662", "abstract": "  The efficiency of extracting topological information from point data depends largely on the complex that is built on top of the data points. From a computational viewpoint, the most favored complexes for this purpose have so far been Vietoris-Rips and witness complexes. While the Vietoris-Rips complex is simple to compute and is a good vehicle for extracting topology of sampled spaces, its size is huge–particularly in high dimensions. The witness complex on the other hand enjoys a smaller size because of a subsampling, but fails to capture the topology in high dimensions unless imposed with extra structures. We investigate a complex called the graph induced complex that, to some extent, enjoys the advantages of both. It works on a subsample but still retains the power of capturing the topology as the Vietoris-Rips complex. It only needs a graph connecting the original sample points from which it builds a complex on the subsample thus taming the size considerably. We show that, using the graph induced complex one can (i) infer the one dimensional homology of a manifold from a very lean subsample, (ii) reconstruct a surface in three dimension from a sparse subsample without computing Delaunay triangulations, (iii) infer the persistent homology groups of compact sets from a sufficiently dense sample. We provide experimental evidences in support of our theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.0662v1.pdf"}
{"id": "1304.1473", "abstract": "  We study the interplay between the Zeeman field and spin-orbit coupling (SOC) in harmonically trapped Fermi gases loaded into a two-dimensional single-band tight-binding optical lattice. Using the Bogoliubov-de Gennes theory, we find that the Zeeman field combined with a Rashba SOC gives rise to (i) Fulde-Ferrell-like superfluidity and (ii) skyrmion-like polarization textures near the edges of the system. We also discussed the effects of interaction, temperature, SOC anisotropy and Zeeman field anisotropy on the superfluid ground state and polarization textures. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.1473v2.pdf"}
{"id": "1304.7437", "abstract": "  The development of the microbunching instability is studied for the linac of the proposed Shanghai Soft X-ray Free-Electron-Laser facility (SXFEL) by analytic formulae as well as numerical simulations with the aid of two different codes. The process is investigated in detail and the growth rates (gains) of the instability under various conditions are compared. The results indicate that the limitations from numerical computations in the present simulation model must be taken into account. Moreover, the appearance of higher-order mode excitations in the simulations suggests that further improvement of the current theory is necessary. A mechanism of introducing shot noise into beam profile as the beam passes through a chicane is proposed. The key issues that drive the instability are analyzed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.7437v1.pdf"}
{"id": "1305.0557", "abstract": "  We provide a detailed description of a general procedure by which a nano/micro-mechanical resonator can be calibrated using its thermal motion. A brief introduction to the equations of motion for such a resonator is presented, followed by a detailed derivation of the corresponding power spectral density (PSD) function. The effective masses for a number of different resonator geometries are determined using both finite element method (FEM) modeling and analytical calculations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.0557v1.pdf"}
{"id": "1305.1001", "abstract": "  We present a renormalizable non supersymmetric Grand Unified SO(10) model which, at the price of a large fine tuning, is compatible with all compelling phenomenological requirements below the unification scale and thus realizes a minimal extension of the SM, unified in SO(10) and describing all known physics below M_GUT. These requirements include coupling unification at a large enough scale to be compatible with the bounds on proton decay; a Yukawa sector in agreement with all the data on quark and lepton masses and mixings and with leptogenesis as the origin of the baryon asymmetry of the Universe; an axion arising from the Higgs sector of the model, suitable to solve the strong CP problem and to account for the observed amount of Dark Matter. The above constraints imposed by the data are very stringent and single out a particular breaking chain with the Pati-Salam group at an intermediate scale M_I∼10^11 GeV. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.1001v2.pdf"}
{"id": "1305.1232", "abstract": "  Presence-only data are referred to situations in which, given a censoring mechanism, a binary response can be observed only with respect to on outcome, usually called presence. In this work we present a Bayesian approach to the problem of presence-only data based on a two levels scheme. A probability law and a case-control design are combined to handle the double source of uncertainty: one due to the censoring and one due to the sampling. We propose a new formalization for the logistic model with presence-only data that allows further insight into inferential issues related to the model. We concentrate on the case of the linear logistic regression and, in order to make inference on the parameters of interest, we present a Markov Chain Monte Carlo algorithm with data augmentation that does not require the a priori knowledge of the population prevalence. A simulation study concerning 24,000 simulated datasets related to different scenarios is presented comparing our proposal to optimal benchmarks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.1232v1.pdf"}
{"id": "1305.3362", "abstract": "  Membrane-fluctuation-induced attraction between ligand–receptor sites binding neighboring membranes is studied using meshless membrane simulations and the Weil–Farago two-dimensional lattice model. For the adhesion sites binding two membranes, this entropic interaction is too weak by itself for the adhesion sites to form a large stable domain. However, it is found that this attraction is enhanced sufficiently to induce large domains either when the sites bind three or more neighboring membranes together or have anchors that harden surrounding membranes. The latter effect is understood by the Asakura–Oosawa type of effective potential in the depletion theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.3362v1.pdf"}
{"id": "1305.4145", "abstract": "  Motivated by recent photoemission experiments on the surface of topological insulators we compute the spectrum of driven topological surface excitations in the presence of an external light source. We completely characterize the spectral function of these non-equilibrium electron excitations for both linear and circular polarizations of the incident light. We find that in the latter case, the circularly polarized light gaps out the surface states, whereas linear polarization gives rise to an anisotropic metal with multiple Dirac cones. We compare the sizes of the gaps with recent pump-probe photoemission measurements and find good agreement. We also identify theoretically several new features in the time-dependent spectral function, such as shadow Dirac cones. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.4145v2.pdf"}
{"id": "1306.0193", "abstract": "  The idea of social participatory sensing provides a substrate to benefit from friendship relations in recruiting a critical mass of participants willing to attend in a sensing campaign. However, the selection of suitable participants who are trustable and provide high quality contributions is challenging. In this paper, we propose a recruitment framework for social participatory sensing. Our framework leverages multi-hop friendship relations to identify and select suitable and trustworthy participants among friends or friends of friends, and finds the most trustable paths to them. The framework also includes a suggestion component which provides a cluster of suggested friends along with the path to them, which can be further used for recruitment or friendship establishment. Simulation results demonstrate the efficacy of our proposed recruitment framework in terms of selecting a large number of well-suited participants and providing contributions with high overall trust, in comparison with one-hop recruitment architecture. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.0193v1.pdf"}
{"id": "1306.1517", "abstract": "  We study the optical conductivity in a (2+1)-dimensional non-relativistic field theory holographically dual to a (3+1)-dimensional charged Lifshitz black brane with the Einstein-Maxwell-dilaton theory. Surprisingly, we find that the optical AC conductivity satisfies the nontrivial (non-)power law scaling in the high frequency regime rather than approaching to a constant when the dynamical critical exponent z>1, which is qualitatively similar to those in various disordered solids in condensed matter systems. Besides, this (non-)power law scaling behavior shows some universality, which is robust against the temperatures. We argue that the peculiar scaling behavior of AC conductivity may stem from the couplings of the dilaton field with the gauge fields and also the logarithmic behavior near the boundary in the Lifshitz spacetime. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.1517v2.pdf"}
{"id": "1306.2113", "abstract": "  Blind quantum computing [A. Broadbent, J. Fitzsimons, and E. Kashefi, Proceedings of the 50th Annual IEEE Symposium on Foundations of Computer Science 517 (2009)] is a secure cloud quantum computing protocol which enables a client (who does not have enough quantum technology at her disposal) to delegate her quantum computation to a server (who has a universal quantum computer) without leaking any relevant information to the server. In [T. Morimae and K. Fujii, Phys. Rev. A 87, 050301(R) (2013)], a new blind quantum computing protocol, so called the measuring-Alice protocol, was proposed. This protocol offers several advantages over previous protocols, such as the device-independent security, less demanding requirements for the client, and a simpler and stronger security based on the no-signaling principle. In this paper, we show composable security of the measuring-Alice protocol by using the formalism of the constructive cryptography [U. Maurer, Proceedings of Theory of Security and Applications, TOSCA 2011, pages 33-56. Springer (2011)]. The above advantages of measuring-Alice protocol enable more intuitive and transparent proofs for the composable security. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.2113v1.pdf"}
{"id": "1306.4984", "abstract": "  We present a fully self-consistent simulation of a synthetic survey of the furthermost cosmic explosions. The appearance of the first generation of stars (Population III) in the Universe represents a critical point during cosmic evolution, signaling the end of the dark ages, a period of absence of light sources. Despite their importance, there is no confirmed detection of Population III stars so far. A fraction of these primordial stars are expected to die as pair-instability supernovae (PISNe), and should be bright enough to be observed up to a few hundred million years after the big bang. While the quest for Population III stars continues, detailed theoretical models and computer simulations serve as a testbed for their observability. With the upcoming near-infrared missions, estimates of the feasibility of detecting PISNe are not only timely but imperative. To address this problem, we combine state-of-the-art cosmological and radiative simulations into a complete and self-consistent framework, which includes detailed features of the observational process. We show that a dedicated observational strategy using ≲ 8 per cent of total allocation time of the James Webb Space Telescope mission can provide us up to ∼ 9-15 detectable PISNe per year. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.4984v3.pdf"}
{"id": "1306.6227", "abstract": "  We consider the interaction between gravitational and electromagnetic radiation propagating on a Minkowski background and look into the effects of the former upon the latter. Not surprisingly, the coupling between these two sources leads to gravitationally driven electromagnetic waves. At the second perturbative level, the driving force appears as the superposition of two waves, the properties of which are decided by the initial conditions. We find that the Weyl-Maxwell interaction typically leads to electromagnetic beat-like signals and, in some cases, to the resonant amplification of the driven electromagnetic wave. For physically reasonable initial conditions, we show that these resonances imply a linear (in time) growth for the amplitude of the electromagnetic signal, with the overall amplification also depending on the strength of the driving gravity wave. Finally, we provide order-of-magnitude estimates of the achieved amplification by applying our analysis to astrophysical environments where both gravitational and electromagnetic waves are expected to coexist. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.6227v3.pdf"}
{"id": "1306.6315", "abstract": "  We derive an exact mapping from the action of nonequilibrium dynamical mean-field theory (DMFT) to a single-impurity Anderson model (SIAM) with time-dependent parameters, which can be solved numerically by exact diagonalization. The representability of the nonequilibrium DMFT action by a SIAM is established as a rather general property of nonequilibrium Green functions. We also obtain the nonequilibrium DMFT equations using the cavity method alone. We show how to numerically obtain the SIAM parameters using Cholesky or eigenvector matrix decompositions. As an application, we use a Krylov-based time propagation method to investigate the Hubbard model in which the hopping is switched on, starting from the atomic limit. Possible future developments are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.6315v1.pdf"}
{"id": "1306.6558", "abstract": "  Nonlinear transport coefficients do not obey, in general, reciprocity relations. We here discuss the magnetic-field asymmetries that arise in thermoelectric and heat transport of mesoscopic systems. Based on a scattering theory of weakly nonlinear transport, we analyze the leading-order symmetry parameters in terms of the screening potential response to either voltage or temperature shifts. We apply our general results to a quantum Hall antidot system. Interestingly, we find that certain symmetry parameters show a dependence on the measurement configuration. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1306/1306.6558v2.pdf"}
{"id": "1307.0512", "abstract": "  In electron field emission experiments, a linear relationship in plots of slope vs. intercept obtained from Fowler-Nordheim analysis is commonly observed for single tips or tip arrays. By simulating samples with many tips, it is shown here that the observed linear relationship results from the distribution of input parameters, assuming a log-normal distribution for the radius of each tip. Typically, a shift from the lower-left to the upper-right of a slope-intercept plot has been correlated with a shift in work function. However, as shown in this paper, the same effect can result from a variation in the number of emitters. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.0512v2.pdf"}
{"id": "1307.1101", "abstract": "  Consider media streaming in MIMO interference networks whereby multiple base stations (BS) simultaneously deliver media to their associated users using fixed data rates. The performance is fundamentally limited by the cross-link interference. We propose a cache-induced opportunistic cooperative MIMO (CoMP) for interference mitigation. By caching a portion of the media files, the BSs opportunistically employ CoMP to transform the cross-link interference into spatial multiplexing gain. We study a mixed-timescale optimization of MIMO precoding and cache control to minimize the transmit power under the rate constraint. The cache control is to create more CoMP opportunities and is adaptive to the long-term popularity of the media files. The precoding is to guarantee the rate requirement and is adaptive to the channel state information and cache state at the BSs. The joint stochastic optimization problem is decomposed into a short-term precoding and a long-term cache control problem. We propose a precoding algorithm which converges to a stationary point of the short-term problem. Based on this, we exploit the hidden convexity of the long-term problem and propose a low complexity and robust solution using stochastic subgradient. The solution has significant gains over various baselines and does not require explicit knowledge of the media popularity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.1101v3.pdf"}
{"id": "1307.1325", "abstract": "  The quantum discord, which quantifies the amount of quantum correlations present between parts of a system, is investigated for antiferromagnetic spin systems. The discord for a pair of spins in the many-spin ground state is related to the diagonal and off-diagonal spin-spin correlation functions and the local magnetization. For isotropic and translationally invariant states, the discord is shown to be a function of the diagonal correlation function only. Thus, near a thermal/quantum critical point, the discord for a pair of spins shows long-range behavior, analogously of the correlation function. The discord exhibits a kink singularity as a function of the anisotropy parameter for the the ground state of the Heisenberg model, for both nearest-neighbor spins as well as for well-separated spins. The preferred measurement basis for the minimum conditional entropy, which determines the discord, changes discontinuously across the critical point. The conditional entropy distribution over all possible the measurement basis is investigated. For the isotropic model, the distribution is just a delta-function, whereas it has a twin-peak structure for anisotropic model. It is shown that the average value and the mean-square fluctuation of the conditional entropy also show a signature of the critical-point behavior. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.1325v1.pdf"}
{"id": "1307.3359", "abstract": "  Lorentz-symmetry and the notion of light cones play a central role in the definition of horizons and the existence of black holes. Current observations provide strong indications that astrophysical black holes do exist in Nature. Here we explore what happens to the notion of a black hole in gravity theories where local Lorentz symmetry is violated, and discuss the relevant astrophysical implications. Einstein-aether theory and Horava gravity are used as the theoretical background for addressing this question. We review earlier results about static, spherically symmetric black holes, which demonstrate that in Lorentz-violating theories there can be a new type of horizon and, hence, a new notion of black hole. We also present both known and new results on slowly rotating black holes in these theories, which provide insights on how generic these new horizons are. Finally, we discuss the differences between black holes in Lorentz-violating theories and in General Relativity, and assess to what extent they can be probed with present and future observations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.3359v2.pdf"}
{"id": "1307.4018", "abstract": "  We show that after a quantum quench of the parameter controlling the number of particles in a Fermi-Hubbard model on scale free graphs, the distribution of energy modes follows a power law dependent on the quenched parameter and the connectivity of the graph. This paper contributes to the literature of quantum quenches on lattices, in which, for many integrable lattice models the distribution of modes after a quench thermalizes to a Generalized Gibbs Ensemble; this paper provides another example of distribution which can arise after relaxation. We argue that the main role is played by the symmetry of the underlying lattice which, in the case we study, is scale free, and to the distortion in the density of modes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.4018v4.pdf"}
{"id": "1307.4866", "abstract": "  We report observations of an X class flare on 2011 September 6 by the instruments onboard the Solar Dynamics Observatory (SDO). The flare occurs in a complex active region with multiple polarities. The Extreme-Ultraviolet (EUV) Variability Experiment (EVE) observations in the warm coronal emission reveal three enhancements, of which the third one corresponds to an EUV late phase. The three enhancements have a one-to-one correspondence to the three stages in flare evolution identified by the spatially-resolved Atmospheric Imaging Assembly (AIA) observations, which are characterized by a flux rope eruption, a moderate filament ejection, and the appearance of EUV late phase loops, respectively. The EUV late phase loops are spatially and morphologically distinct from the main flare loops. Multi-channel analysis suggests the presence of a continuous but fragmented energy injection during the EUV late phase resulting in the warm corona nature of the late phase loops. Based on these observational facts, We propose a three-stage magnetic reconnection scenario to explain the flare evolution. Reconnections in different stages involve different magnetic fields but show a casual relationship between them. The EUV late phase loops are mainly produced by the least energetic magnetic reconnection in the last stage. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.4866v1.pdf"}
{"id": "1307.5427", "abstract": "  We propose a model for the two-dimensional electron gas formed at the interface of oxide heterostructures that includes a Rashba spin-orbit coupling proportional to an electric field oriented perpendicularly to the interface. Taking into account the electron density dependence of this electric field confining the electron gas at the interface, we report the occurrence of a phase separation instability (signaled by a negative compressibility) for realistic values of the spin-orbit coupling and of the electronic band-structure parameters at zero temperature. We extend the analysis to finite temperatures and in the presence of an in-plane magnetic field, thereby obtaining two phase diagrams which exhibit a phase separation dome. By varying the gating potential the phase separation dome may shrink and vanish at zero temperature into a quantum critical point where the charge fluctuates dynamically. Similarly the phase separation may be spoiled by a planar magnetic field even at zero temperature leading to a line of quantum critical points. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.5427v3.pdf"}
{"id": "1307.5636", "abstract": "  We generalize Pearl's back-door criterion for directed acyclic graphs (DAGs) to more general types of graphs that describe Markov equivalence classes of DAGs and/or allow for arbitrarily many hidden variables. We also give easily checkable necessary and sufficient graphical criteria for the existence of a set of variables that satisfies our generalized back-door criterion, when considering a single intervention and a single outcome variable. Moreover, if such a set exists, we provide an explicit set that fulfills the criterion. We illustrate the results in several examples. R-code is available in the R-package pcalg. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.5636v3.pdf"}
{"id": "1307.5639", "abstract": "  We present a self-consistent hydrodynamical simulation of a Milky Way-like galaxy, at the resolution of 0.05 pc. The model includes star formation and a new implementation of stellar feedback through photo-ionization, radiative pressure and supernovae. The simulation resolves the structure of the interstellar medium at subparsec resolution for a few cloud lifetimes, and at 0.05 pc for about a cloud crossing time. Turbulence cascade and gravitation from the kpc scales are de facto included in smaller structures like molecular clouds. We show that the formation of a bar influences the dynamics of the central  100 pc by creating resonances. At larger radii, the spiral arms host the formation of regularly spaced clouds: beads on a string and spurs. These instabilities pump turbulent energy into the gas, generally in the supersonic regime. Because of asymmetric drift, the supernovae explode outside of their gaseous nursery, which diminishes the effect of feedback on the structure of clouds. The evolution of clouds is thus mostly due to fragmentation and gas consumption, regulated mainly by supersonic turbulence. The transition from turbulence supported to self-gravitating gas is detected in the gas density probability distribution function at  2000 cm^-3. The power spectrum density suggests that gravitation governs the hierarchical organisation of structures from the galactic scale down to a few parsecs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.5639v2.pdf"}
{"id": "1307.7107", "abstract": "  Wireless Body Area Sensor Network (WBASN) is a technology employed mainly for patient health monitoring. New research is being done to take the technology to the next level i.e. player's fatigue monitoring in sports. Muscle fatigue is the main cause of player's performance degradation. This type of fatigue can be measured by sensing the accumulation of lactic acid in muscles. Excess of lactic acid makes muscles feel lethargic. Keeping this in mind we propose a protocol THreshold based Energy-efficient FAtigue MEasurement (THE-FAME) for soccer players using WBASN. In THE-FAME protocol, a composite parameter has been used that consists of a threshold parameter for lactic acid accumulation and a parameter for measuring distance covered by a particular player. When any parameters's value in this composite parameter shows an increase beyond threshold, the players is declared to be in a fatigue state. The size of battery and sensor should be very small for the sake of players' best performance. These sensor nodes, implanted inside player's body, are made energy efficient by using multiple sinks instead of a single sink. Matlab simulation results show the effectiveness of THE-FAME. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.7107v1.pdf"}
{"id": "1307.7185", "abstract": "  The performance of a relay-based cellular network is greatly affected by the relay location within a cell. Existing results for optimal relay placement do not reflect how the radio propagation environment and choice of the coding scheme can impact system performance. In this paper, we analyze the impact on relaying performance of node distances, relay height and line-of-sight conditions for both uplink and downlink transmissions, using several relay coding schemes. Our first objective is to propose a geometrical model for energy-efficient relay placement that requires only a small number of characteristic distances. Our second objective is to estimate the maximum cell coverage of a relay-aided cell given power constraints, and conversely, the averaged energy consumption given a cell radius. We show that the practical full decode-forward scheme performs close to the energy-optimized partial decode-forward scheme when the relay is ideally located. However, away from this optimum relay location, performance rapidly degrades and more advanced coding scheme, such as partial decode-forward, is needed to maintain good performance and allow more freedom in the relay placement. Finally, we define a trade-off between cell coverage and energy efficiency, and show that there exists a relay location for which increasing the cell coverage has a minimal impact on the average energy consumed per unit area. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.7185v2.pdf"}
{"id": "1307.7461", "abstract": "  We provide a systematic analysis of levels of integration between discrete high-level reasoning and continuous low-level reasoning to address hybrid planning problems in robotics. We identify four distinct strategies for such an integration: (i) low-level checks are done for all possible cases in advance and then this information is used during plan generation, (ii) low-level checks are done exactly when they are needed during the search for a plan, (iii) first all plans are computed and then infeasible ones are filtered, and (iv) by means of replanning, after finding a plan, low-level checks identify whether it is infeasible or not; if it is infeasible, a new plan is computed considering the results of previous low- level checks. We perform experiments on hybrid planning problems in robotic manipulation and legged locomotion domains considering these four methods of integration, as well as some of their combinations. We analyze the usefulness of levels of integration in these domains, both from the point of view of computational efficiency (in time and space) and from the point of view of plan quality relative to its feasibility. We discuss advantages and disadvantages of each strategy in the light of experimental results and provide some guidelines on choosing proper strategies for a given domain. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.7461v1.pdf"}
{"id": "1307.7617", "abstract": "  The enthalpies of solution of H in Zr binary intermetallic compounds formed with Cu, Cr, Fe, Mo, Ni, Nb, Sn and V were calculated by means of density functional theory simulations and compared to that of H in α-Zr. It is predicted that all Zr-rich phases (formed with Cu, Fe, Ni and Sn), and those phases formed with Nb and V, offer lower energy, more stable sites for H than α-Zr. Conversely, Mo and Cr containing phases do not provide preferential solution sites for H. In all cases the most stable site for H are those that offer the highest coordination fraction of Zr atoms. Often these are four Zr tetrahedra but not always. Implications with respect to H-trapping properties of commonly observed ternary phases such as Zr(Cr,Fe)2, Zr2(Fe,Ni) and Zr(Nb,Fe)2 are also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.7617v1.pdf"}
{"id": "1308.0231", "abstract": "  The electron spin degree of freedom can play a significant role in relativistic scattering processes involving intense laser fields. In this contribution we discuss the influence of the electron spin on (i) Kapitza-Dirac scattering in an x-ray laser field of high intensity, (ii) photo-induced electron-positron pair production in a strong laser wave and (iii) multiphoton electron-positron pair production on an atomic nucleus. We show that in all cases under consideration the electron spin can have a characteristic impact on the process properties and their total probabilities. To this end, spin-resolved calculations based on the Dirac equation in the presence of an intense laser field are performed. The predictions from Dirac theory are also compared with the corresponding results from the Klein-Gordon equation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.0231v2.pdf"}
{"id": "1308.1971", "abstract": "  This paper presents an asynchronous distributed algorithm to manage multiple trees for peer-to-peer streaming in a flow level model. It is assumed that videos are cut into substreams, with or without source coding, to be distributed to all nodes. The algorithm guarantees that each node receives sufficiently many substreams within delay logarithmic in the number of peers. The algorithm works by constantly updating the topology so that each substream is distributed through trees to as many nodes as possible without interference. Competition among trees for limited upload capacity is managed so that both coverage and balance are achieved. The algorithm is robust in that it efficiently eliminates cycles and maintains tree structures in a distributed way. The algorithm favors nodes with higher degree, so it not only works for live streaming and video on demand, but also in the case a few nodes with large degree act as servers and other nodes act as clients.   A proof of convergence of the algorithm is given assuming instantaneous update of depth information, and for the case of a single tree it is shown that the convergence time is stochastically tightly bounded by a small constant times the log of the number of nodes. These theoretical results are complemented by simulations showing that the algorithm works well even when most assumptions for the theoretical tractability do not hold. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.1971v1.pdf"}
{"id": "1308.2179", "abstract": "  Thermoelectric transport involving an arbitrary number of terminals is discussed in the presence of a magnetic field breaking time-reversal symmetry within the linear response regime using the Landauer-Büttiker formalism. We derive a universal bound on the Onsager coefficients that depends only on the number of terminals. This bound implies bounds on the efficiency and on efficiency at maximum power for heat engines and refrigerators. For isothermal engines pumping particles and for absorption refrigerators these bounds become independent even of the number of terminals. On a technical level, these results follow from an original algebraic analysis of the asymmetry index of doubly substochastic matrices and their Schur complements. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.2179v1.pdf"}
{"id": "1308.3168", "abstract": "  We present the results of speckle interferometric observations of 273 magnetic stars most of which are Ap/Bp type. All observations were made at the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. We resolved 58 binary and 5 triple stars into individual components. Almost half of these stars were astrometrically resolved for the first time. The fraction of speckle interferometric binaries/multiples in the sample of stars with confirmed magnetic fields is 23", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.3168v2.pdf"}
{"id": "1308.3343", "abstract": "  In a quest to further our understanding of the diffuse interstellar medium (ISM) as well as the unidentified carriers of the diffuse interstellar bands (DIBs), we are mapping DIBs across the sky using hundreds of hot stars as background torches - globular clusters (in particular omega Centauri), nearby stars in and around the Local Bubble, and stars within the Magellanic Clouds. I describe the results so far obtained and our current experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.3343v1.pdf"}
{"id": "1308.3424", "abstract": "  Batteries are pivotal components in overcoming some of today's greatest technological challenges. Yet to date there is no self-consistent atomistic description of a complete battery. We take first steps toward modeling of a battery as a whole microscopically. Our focus lies on phenomena occurring at the electrode-electrolyte interface which are not easily studied with other methods. We use the redox split-charge equilibration (redoxSQE) method that assigns a discrete ionization state to each atom. Along with exchanging partial charges across bonds, atoms can swap integer charges. With redoxSQE we study the discharge behavior of a nano-battery, and demonstrate that this reproduces the generic properties of a macroscopic battery qualitatively. Examples are the dependence of the battery's capacity on temperature and discharge rate, as well as performance degradation upon recharge. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.3424v1.pdf"}
{"id": "1308.4794", "abstract": "  We study the dynamics of the oscillating gauged scalar field in a thermal bath. A Langevin type equation of motion of the scalar field, which contains both dissipation and fluctuation terms, is derived by using the real-time finite temperature effective action approach. The existence of the quantum fluctuation-dissipation relation between the non-local dissipation term and the Gaussian stochastic noise terms is verified. We find the noise variables are anti-correlated at equal-time. The dissipation rate for the each mode is also studied, which turns out to depend on the wavenumber. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.4794v2.pdf"}
{"id": "1308.4866", "abstract": "  We report on the microscopic magnetic modeling of the spin-1/2 copper mineral malachite at ambient and elevated pressures. Despite the layered crystal structure of this mineral, the ambient-pressure susceptibility and magnetization data can be well described by an unfrustrated quasi-one-dimensional magnetic model. Weakly interacting antiferromagnetic alternating spin chains are responsible for a large spin gap of 120K. Although the intradimer Cu-O-Cu bridging angles are considerably smaller than the interdimer angles, density functional theory (DFT) calculations revealed that the largest exchange coupling of 190K operates within the structural dimers. The lack of the inversion symmetry in the exchange pathways gives rise to sizable Dzyaloshinskii-Moriya interactions which were estimated by full-relativistic DFT+U calculations. Based on available high-pressure crystal structures, we investigate the exchange couplings under pressure and make predictions for the evolution of the spin gap. The calculations evidence that intradimer couplings are strongly pressure-dependent and their evolution underlies the decrease of the spin gap under pressure. Finally, we assess the accuracy of hydrogen positions determined by structural relaxation within DFT and put forward this computational method as a viable alternative to elaborate experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.4866v1.pdf"}
{"id": "1308.4953", "abstract": "  We consider a spherically symmetric gravitational collapse of a tachyon field with an inverse square potential, which is coupled with a barotropic fluid. By employing an holonomy correction imported from loop quantum cosmology, we analyse the dynamics of the collapse within a semiclassical description. Using a dynamical system approach, we find that the stable fixed points given by the standard general relativistic setting turn into saddle points in the present context. This provides a new dynamics in contrast to the black hole and naked singularities solutions appearing in the classical model. Our results suggest that classical singularities can be avoided by quantum gravity effects and are replaced by a bounce. By a thorough numerical studies we show that, depending on the barotropic parameter γ, there exists a class of solutions corresponding to either a fluid or a tachyon dominated regimes. Furthermore, for the case γ∼ 1, we find an interesting tracking behaviour between the tachyon and the fluid leading to a dust-like collapse. In addition, we show that, there exists a threshold scale which determines when an outward energy flux emerges, as a non-singular black hole is forming, at the corresponding collapse final stages. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.4953v3.pdf"}
{"id": "1308.5357", "abstract": "  An unconventional pairing mechanism in the heavy-fermion material URu_2Si_2 is studied. We propose a mixed singlet-triplet d-density wave to be the hidden-order state in URu_2Si_2. The exotic order is topologically nontrivial and supports a charge 2e skyrmionic spin texture, which is assumed to fractionalize into merons and antimerons at the deconfined quantum critical point. The interaction between these fractional particles results in a (pseudo)spin-singlet chiral d-wave superconducting state, which breaks time reversal symmetry. Therefore, it is highly likely to produce a nonzero signal of the polar Kerr effect at the onset of the superconductivity, consistent with recent experiments. In addition, the nodal structures of the possible pairing functions in our model are consistent with the thermodynamic experiments in URu_2Si_2. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.5357v4.pdf"}
{"id": "1308.5498", "abstract": "  Over the 3-year active period from 2008 September to 2011 November, the outburst behavior of the Be/X-ray binary A 0535+26 was continuously monitored with the MAXI/GSC and the Swift/BAT. The source exhibited nine outbursts, every binary revolution of 111.1 days, of which two are categorized into the giant (type-II) outbursts. The recurrence period of these outbursts is found to be ∼115 days, significantly longer than the orbital period of 111.1 days. With the MAXI/GSC, a low-level active period, or a \"precursor\", was detected prior to at least four giant outbursts. The precursor recurrence period agrees with that of the giant outbursts. The period difference of the giant outbursts from the orbital period is possibly related with some structures in the circumstellar disc formed around the Be companion. Two scenarios, one based on a one-armed disc structure and the other a Be-disc precession, are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.5498v1.pdf"}
{"id": "1308.6743", "abstract": "  The framework of the Standard-Model Extension (SME) provides a relativistic quantum field theory for the study of Lorentz violation. The classical, nonrelativistic equations of motion can be extracted as a limit that is useful in various scenarios. In this work, we consider the effects of certain SME coefficients for Lorentz violation on the motion of macroscopic objects having net intrinsic spin in the classical, nonrelativistic limit. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.6743v1.pdf"}
{"id": "1309.3183", "abstract": "  We investigate the robustness of singularity avoidance mechanisms in nonrelativistic quantum mechanics on the discretised real line when lattice points are allowed to approach a singularity of the classical potential. We consider the attractive Coulomb potential and the attractive scale invariant potential, on an equispaced parity-noninvariant lattice and on a non-equispaced parity-invariant lattice, and we examine the energy eigenvalues by a combination of analytic and numerical techniques. While the lowest one or two eigenvalues descend to negative infinity in the singular limit, we find that the higher eigenvalues remain finite and form degenerate pairs, close to the eigenvalues of a theory in which a lattice point at the singularity is regularised either by Thiemann's loop quantum gravity singularity avoidance prescription or by a restriction to the odd parity sector. The approach to degeneracy can be reproduced from a nonsingular discretised half-line quantum theory by tuning a boundary condition parameter. The results show that Thiemann's singularity avoidance prescription and the discretised half-line boundary condition reproduce quantitatively correct features of the singular limit spectrum apart from the lowest few eigenvalues. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.3183v2.pdf"}
{"id": "1309.4801", "abstract": "  Brownian particles in random potentials show an extended regime of subdiffusive dynamics at intermediate times. The asymptotic diffusive behavior is often established at very long times and thus cannot be accessed in experiments or simulations. For the case of one-dimensional random potentials with Gaussian distributed energies, we present a detailed analysis of experimental and simulation data. It is shown that the asymptotic long-time diffusion coefficient can be related to the behavior at intermediate times, namely the minimum of the exponent that characterizes subdiffusion and hence corresponds to the maximum degree of subdiffusion. As a consequence, investigating only the dynamics at intermediate times is sufficient to predict the order of magnitude of the long-time diffusion coefficient and the timescale at which the crossover from subdiffusion to diffusion occurs, i.e. when the long-time diffusive regime and hence thermal equilibrium is established. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.4801v1.pdf"}
{"id": "1309.5017", "abstract": "  We extend the Wigner-Weyl-Moyal phase-space formulation of quantum mechanics to general curved configuration spaces. The underlying phase space is based on the chosen coordinates of the manifold and their canonically conjugate momenta. The resulting Wigner function displays the axioms of a quasiprobability distribution, and any Weyl-ordered operator gets associated with the corresponding phase-space function, even in the absence of continuous symmetries. The corresponding quantum Liouville equation reduces to the classical curved space Liouville equation in the semiclassical limit. We demonstrate the formalism for a point particle moving on two-dimensional manifolds, such as a paraboloid or the surface of a sphere. The latter clarifies the treatment of compact coordinate spaces as well as the relation of the presented phase-space representation to symmetry groups of the configuration space. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.5017v2.pdf"}
{"id": "1309.5331", "abstract": "  We present a method to measure the absolute surface resistance of conductive samples at a set of GHz frequencies with superconducting lead stripline resonators at temperatures 1- 6K. The stripline structure can easily be applied for bulk samples and allows direct calculation of the surface resistance without the requirement of additional calibration measurements or sample reference points. We further describe a correction method to reduce experimental background on high-Q resonance modes by exploiting TEM-properties of the external cabling. We then show applications of this method to the reference materials gold, tantalum, and tin, which include the anomalous skin effect and conventional superconductivity. Furthermore, we extract the complex optical conductivity for an all-lead stripline resonator to find a coherence peak and the superconducting gap of lead. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.5331v2.pdf"}
{"id": "1309.5429", "abstract": "  We derive an ab initio π-band tight-binding model for AB stacked bilayer graphene based on maximally localized Wannier wave functions (MLWFs) centered on the carbon sites, finding that both intralayer and interlayer hopping is longer in range than assumed in commonly used phenomenological tight-binding models. Starting from this full tight-binding model, we derive two effective models that are intended to provide a convenient starting point for theories of π-band electronic properties by achieving accuracy over the full width of the π-bands, and especially at the Dirac points, in models with a relatively small number of hopping parameters. The simplified models are then compared with phenomenological Slonczewski-Weiss-McClure type tight-binding models in an effort to clarify confusions that exists in the literature concerning tight-binding model parameter signs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.5429v1.pdf"}
{"id": "1309.6175", "abstract": "  HD 202850 is a late B-type supergiant. It is known that photospheric lines of such stars vary. Due to macroturbulence the lines are much wider than expected. Macroturbulence has been linked to stellar pulsations. It has been reported that there are several B supergiants that undergo pulsations. In our previous work, we detected a pulsational period of 1.59 hours in this object from data taken with the Ondrejov 2-m telescope. We continued to investigate this object and we took several time series with the DAO 1.2-m telescope. Our new data suggest that there may be some additional pulsational periods in this star. We present our new results in this poster. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.6175v2.pdf"}
{"id": "1309.7078", "abstract": "  The possibility of thermal excitation of intrinsic localized modes (ILMs) arising from anharmonicity in ionic perfect crystals is studied numerically for realistic model systems in one and three dimensions. Implications are discussed for an interesting high-temperature feature seen in earlier inelastic neutron scattering experiments on single crystal NaI. The general conclusion is that ILM formation energies are far too large for thermal excitation of ILMs to account for the observed feature in a pure crystal. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.7078v1.pdf"}
{"id": "1309.7415", "abstract": "  Utilizing dual descriptions of the normal cone of convex optimization problems in conic form, we characterize the vertices of semidefinite representations arising from Lovász theta body, generalizations of the elliptope, and related convex sets. Our results generalize vertex characterizations due to Laurent and Poljak from the 1990's. Our approach also leads us to nice characterizations of strict complementarity and to connections with some of the related literature. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.7415v1.pdf"}
{"id": "1309.7786", "abstract": "  We provide a brief summary of the history of galaxy structure studies. We also introduce several large-scale redshift surveys and summarize the most commonly used methods to identify the groups and clusters of galaxies. We present several catalogues of galaxy groups.These catalogues can be used to study the galaxy groups in different environments. We also consider the properties of superclusters of galaxies in the nearby Universe and describe the largest system of galaxies observed - the Sloan Great Wall. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.7786v2.pdf"}
{"id": "1309.7797", "abstract": "  We consider heavy particles immersed in a Fermi sea of light fermions, and study the interaction between the heavy particles induced by the surrounding light fermions. With the Born-Oppenheimer method, we analytically show that the induced interaction between N heavy particles vanishes for any N in the limit of high light-fermion density. The induced interaction vanishes even in the unitarity regime. This suggests that the formation of N-body bound states associated with the Efimov effect is suppressed in the presence of the dense Fermi sea. We ascribe the vanishing induced interaction to the screening effect in the neutral Fermi system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.7797v1.pdf"}
{"id": "1310.0197", "abstract": "  Constructing compact quantum circuits for universal quantum gates on solid-state systems is crucial for quantum computing. We present some compact quantum circuits for a deterministic solid-state quantum computing, including the CNOT, Toffoli, and Fredkin gates on the diamond nitrogen-vacancy centers confined inside cavities, achieved by some input-output processes of a single photon. Our quantum circuits for these universal quantum gates are simple and economic. Moreover, additional electron qubits are not employed, but only a single-photon medium. These gates have a long coherent time. We discuss the feasibility of these universal solid-state quantum gates, concluding that they are feasible with current technology. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.0197v2.pdf"}
{"id": "1310.0948", "abstract": "  We present timing and broad-band spectral studies of the high mass X-ray binary pulsar 4U 1909+07 using data from Suzaku observation during 2010 November 2-3. The pulse period of the pulsar is estimated to be 604.11+/-0.14 s. Pulsations are seen in the X-ray light curve up to  70 keV. The pulse profile is found to be strongly energy-dependent: a complex, multi-peaked structure at low energy that becomes a simple single peak at higher energy. We found that the 1-70 keV pulse averaged continuum can be fitted by the sum of a black body and a partial covering Negative and Positive power-law with EXponential cutoff (NPEX) model. A weak iron fluorescence emission line at 6.4 keV was detected in the spectrum. An absorption like feature at  44 keV was clearly seen in the residue of the spectral fitting, independent of the continuum model adopted. To check the possible presence of a CRSF in the spectrum, we normalized the pulsar spectrum with the spectrum of the Crab Nebula. The resulting Crab ratio also showed a clear dip centered at  44 keV. We performed statistical tests on the residue of the spectral fitting and also on the Crab spectral ratio to determine the significance of the absorption like feature and identified it as a CRSF of the pulsar. We estimated the corresponding surface magnetic field of the pulsar to be 3.8 x 10^12 Gauss. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.0948v1.pdf"}
{"id": "1310.1573", "abstract": "  A popular view in contemporary Boltzmannian statistical mechanics is to interpret the measures as typicality measures. In measure-theoretic dynamical systems theory measures can similarly be interpreted as typicality measures. However, a justification why these measures are a good choice of typicality measures is missing, and the paper attempts to fill this gap. The paper first argues that Pitowsky's (2012) justification of typicality measures does not fit the bill. Then a first proposal of how to justify typicality measures is presented. The main premises are that typicality measures are invariant and are related to the initial probability distribution of interest (which are translation-continuous or translation-close). The conclusion are two theorems which show that the standard measures of statistical mechanics and dynamical systems are typicality measures. There may be other typicality measures, but they agree about judgements of typicality. Finally, it is proven that if systems are ergodic or epsilon-ergodic, there are uniqueness results about typicality measures. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.1573v1.pdf"}
{"id": "1310.2761", "abstract": "  Quasi-particle interference (QPI) measurements have provided a powerful tool for determining the momentum dependence of the gap of unconventional superconductors. Here we examine the possibility of using such measurements to probe the frequency and momentum dependence of the electron self-energy. For illustration, we calculate the QPI response function for a cuprate-like Fermi surface with an electron self-energy from an RPA approximation. Then we try to reextract the self-energy from the dispersion of the peaks in the QPI response function using different approaches. We show that in principle it is possible to extract the self-energy from the QPI response for certain nested momentum directions. We discuss some of the limitations that one faces. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.2761v1.pdf"}
{"id": "1310.3536", "abstract": "  The Chern number is a genuine topological number. On the other hand, a symmetry protected topological (SPT) charge is a topological number only when a symmetry exists. We propose a formula for the SPT charge as a derivative of the Chern number in terms of the Green function in such a way that it is valid and related to the associated Hall current even when the symmetry is broken. We estimate the amount of deviation from the quantized value as a function of the strength of the broken symmetry. We present two examples. First, we consider Dirac electrons with the spin-orbit coupling on honeycomb lattice, where the SPT charges are given by the spin-Chern, valley-Chern and spin-valley-Chern numbers. Though the spin-Chern charge is not quantized in the presence of the Rashba coupling, the deviation is estimated to be 10^-7 in the case of silicene, a silicon cousin of graphene. Second, we analyze the effect of the mirror-symmetry breaking of the mirror-Chern number in a thin-film of topological crystalline insulator. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.3536v2.pdf"}
{"id": "1310.3944", "abstract": "  In view of the increasing importance of non-Gaussian entangled states in quantum information protocols like teleportation and violations of Bell inequalities, the steering of continuous variable non-Gaussian entangled states is investigated. The EPR steering for Gaussian states may be demonstrated through the violation of the Reid inequality involving products of the inferred variances of non-commuting observables. However, for arbitrary states the Reid inequality is not always necessary because of the higher order correlations in such states. One then needs to use the entropic steering inequality. We examine several classes of currently important non-Gaussian entangled states, such as the two-dimensional harmonic oscillator, the photon subtracted two mode squeezed vacuum, and the NOON state, in order to demonstrate the steering property of such states. A comparative study of the violation of the Bell-inequality for these states shows that the entanglement present is more easily revealed through steering compared to Bell-violation for several such states. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.3944v2.pdf"}
{"id": "1310.4911", "abstract": "  We investigate the dependence of the critical Binder cumulant of the magnetization and the largest Fortuin-Kasteleyn cluster on the boundary conditions and aspect ratio of the underlying square Ising lattices. By means of the Swendsen-Wang algorithm, we generate numerical data for large system sizes and we perform a detailed finite-size scaling analysis for several values of the aspect ratio r, for both periodic and free boundary conditions. We estimate the universal probability density functions of the largest Fortuin-Kasteleyn cluster and we compare it to those of the magnetization at criticality. It is shown that these probability density functions follow similar scaling laws, and it is found that the values of the critical Binder cumulant of the largest Fortuin-Kasteleyn cluster are upper bounds to the values of the respective order-parameter's cumulant, with a splitting behavior for large values of the aspect ratio. We also investigate the dependence of the amplitudes of the magnetization and the largest Fortuin-Kasteleyn cluster on the aspect ratio and boundary conditions. We find that the associated exponents, describing the aspect ratio dependencies, are different for the magnetization and the largest Fortuin-Kasteleyn cluster, but in each case are independent of boundary conditions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.4911v3.pdf"}
{"id": "1310.5112", "abstract": "  The window is found in the space of the free parameters of the theory of viscoelastic matter for which the Friedmann singularity is stable. Under stability we mean that in the presence of the shear stresses the generic solution of the equations of relativistic gravity possessing the isotropic, homogeneous and thermally equilibrated cosmological singularity exists. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.5112v1.pdf"}
{"id": "1310.5323", "abstract": "  We use the approach of \"transitionless quantum driving\" proposed by Berry to construct shortcuts to the population transfer and the creation of maximal entanglement between two Λ-type atoms based on the cavity quantum electronic dynamics (CQED) system. An effective Hamiltonian is designed by resorting to an auxiliary excited level, a classical driving field and an extra cavity field mode to supplement or substitute the original reference Hamiltonian, and steer the system evolution along its instantaneous eigenstates in an arbitrarily short time, speeding up the rate of population transfer and creation of maximal entanglement between the two atoms inside a cavity. Numerical simulation demonstrates that our shortcuts' performance is robust against the decoherences caused by atomic spontaneous emission and cavity photon leakage. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.5323v2.pdf"}
{"id": "1310.5325", "abstract": "  We say that two (or more) state assignments for one and the same quantum system are compatible if they could represent the assignments of observers with differing information about the system. A criterion for compatibility was proposed in [Phys. Rev. A 65, 032315 (2002)]; however, this leaves unanswered the question of whether there are degrees of compatibility which could be represented by some quantitative measure, and whether there is a straightforward procedure whereby the observers can pool their information to arrive at a unique joint state assignment. We argue that such measures are only sensible given some assumption about what kind of information was used in making the state assignments in the first place, and that in general state assignments do not represent all of the information possessed by the observers. However, we examine one particular measure, and show that it has a straightforward interpretation, assuming that the information was acquired from a particular type of measurement, and that in this case there is a natural rule for pooling information. We extend this measure to compatibility of states for k observers, and show that the value is the solution to a semidefinite program. Similar compatibility measures can be defined for alternative notions of state compatibility, including Post-Peierls (PP) and Equal Support (ES) compatibility. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.5325v2.pdf"}
{"id": "1310.7155", "abstract": "  We present and study cosmic voids identified using the watershed void finder VIDE in the Sloan Digital Sky Survey Data Release 9, compare these voids to ones identified in mock catalogs, and assess the impact of the survey mask on void statistics such as number functions, ellipticity distributions, and radial density profiles. The nearly 1,000 identified voids span three nearly volume-limited samples from redshift z = 0.43 to 0.7. For comparison we use 98 of the publicly available 2LPT-based mock galaxy catalogs of Manera et al., and also generate our own mock catalogs by applying a Halo Occupation Distribution model to an N-body simulation. We find that the mask reduces the number density of voids at all scales by a factor of three and slightly skews the relative size distributions. This engenders an increase in the mean ellipticity by roughly 30", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.7155v2.pdf"}
{"id": "1310.7167", "abstract": "  The mechanism of the initial inflationary scenario of the universe and of its late-time acceleration can be described by assuming the existence of some gravitationally coupled scalar fields ϕ, with the inflaton field generating inflation and the quintessence field being responsible for the late accelerated expansion. Various inflationary and late-time accelerated scenarios are distinguished by the choice of an effective self-interaction potential V(ϕ ), which simulates a temporarily non-vanishing cosmological term. In this work, we present a new formalism for the analysis of scalar fields in flat isotropic and homogeneous cosmological models. The basic evolution equation of the models can be reduced to a first order non-linear differential equation. Approximate solutions of this equation can be constructed in the limiting cases of the scalar field kinetic energy and potential energy dominance, respectively, as well as in the intermediate regime. Moreover, we present several new accelerating and decelerating exact cosmological solutions, based on the exact integration of the basic evolution equation for scalar field cosmologies. More specifically, exact solutions are obtained for exponential, generalized cosine hyperbolic, and power law potentials, respectively. Cosmological models with power law scalar field potentials are also analyzed in detail. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.7167v4.pdf"}
{"id": "1311.3646", "abstract": "  We consider a basic content distribution scenario consisting of a single origin server connected through a shared bottleneck link to a number of users each equipped with a cache of finite memory. The users issue a sequence of content requests from a set of popular files, and the goal is to operate the caches as well as the server such that these requests are satisfied with the minimum number of bits sent over the shared link. Assuming a basic Markov model for renewing the set of popular files, we characterize approximately the optimal long-term average rate of the shared link. We further prove that the optimal online scheme has approximately the same performance as the optimal offline scheme, in which the cache contents can be updated based on the entire set of popular files before each new request. To support these theoretical results, we propose an online coded caching scheme termed coded least-recently sent (LRS) and simulate it for a demand time series derived from the dataset made available by Netflix for the Netflix Prize. For this time series, we show that the proposed coded LRS algorithm significantly outperforms the popular least-recently used (LRU) caching algorithm. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1311/1311.3646v1.pdf"}
{"id": "1311.5757", "abstract": "  In this paper we look at some of the design issues that affect the success of multimodal displays that combine acoustic and haptic modalities. First, issues affecting successful sonification design are explored and suggestions are made about how the language of electroacoustic music can assist. Next, haptic interaction is introduced in the light of this discussion, particularly focusing on the roles of gesture and mimesis. Finally, some observations are made regarding some of the issues that arise when the haptic and acoustic modalities are combined in the interface. This paper looks at examples of where auditory and haptic interaction have been successfully combined beyond the strict confines of the human-computer application interface (musical instruments in particular) and discusses lessons that may be drawn from these domains and applied to the world of multimodal human-computer interaction. The argument is made that combined haptic-auditory interaction schemes can be thought of as musical instruments and some of the possible ramifications of this are raised. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1311/1311.5757v1.pdf"}
{"id": "1311.6384", "abstract": "  We study a model of the generalized Brans-Dicke gravity presented in both the Jordan and in the Einstein frames, which are conformally related. We show that the scalar field equations in the Einstein frame are reduced to the geodesics equations on the target space of the nonlinear sigma-model. The analytical solutions in elliptical functions are obtained when the conformal couplings are given by reciprocal exponential functions. The behavior of the scale factor in the Jordan frame is studied using numerical computations. For certain parameters the solutions can describe an accelerated expansion. We also derive an analytical approximation in exponential functions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1311/1311.6384v2.pdf"}
{"id": "1311.7482", "abstract": "  Random effects are implemented for aster models using two approximations taken from Breslow and Clayton [J. Amer. Statist. Assoc. 88 (1993) 9-25]. Random effects are analytically integrated out of the Laplace approximation to the complete data log likelihood, giving a closed-form expression for an approximate missing data log likelihood. Third and higher derivatives of the complete data log likelihood with respect to the random effects are ignored, giving a closed-form expression for second derivatives of the approximate missing data log likelihood, hence approximate observed Fisher information. This method is applicable to any exponential family random effects model. It is implemented in the CRAN package aster (R Core Team [R: A Language and Environment for Statistical Computing (2012) R Foundation for Statistical Computing], Geyer [R package aster (2012) http://cran.r-project.org/package=aster]). Applications are analyses of local adaptation in the invasive California wild radish (Raphanus sativus) and the slender wild oat (Avena barbata) and of additive genetic variance for fitness in the partridge pea (Chamaecrista fasciculata). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1311/1311.7482v1.pdf"}
{"id": "1312.0905", "abstract": "  So far spin foam models are hardly understood beyond a few of their basic building blocks. To make progress on this question, we define analogue spin foam models, so called spin nets, for quantum groups SU(2)_k and examine their effective continuum dynamics via tensor network renormalization. In the refinement limit of this coarse graining procedure, we find a vast non-trivial fixed point structure beyond the degenerate and the BF phase. In comparison to previous work, we use fixed point intertwiners, inspired by Reisenberger's construction principle [1] and the recent work [2], as the initial parametrization. In this new parametrization fine tuning is not required in order to flow to these new fixed points. Encouragingly, each fixed point has an associated extended phase, which allows for the study of phase transitions in the future. Finally we also present an interpretation of spin nets in terms of melonic spin foams. The coarse graining flow of spin nets can thus be interpreted as describing the effective coupling between two spin foam vertices or space time atoms. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.0905v2.pdf"}
{"id": "1312.2157", "abstract": "  The relative permittivity dyadic of a dielectric structurally chiral material (SCM) varies helicoidally along a fixed direction; in consequence, the SCM exhibits the circular Bragg phenomenon, which is the circular-polarization-selective reflection of light. The introduction of hyperbolicity in an SCM—by making either one or two but not all three eigenvalues of the relative permittivity dyadic acquire negative real parts—does not eliminate the circular Bragg phenomenon, but significantly alters the regime for its exhibition. Physical vapor deposition techniques appear to be suitable to fabricate hyperbolic SCMs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.2157v1.pdf"}
{"id": "1312.2461", "abstract": "  The global-in-time existence and uniqueness of bounded weak solutions to a spinorial matrix drift-diffusion model for semiconductors is proved. Developing the electron density matrix in the Pauli basis, the coefficients (charge density and spin-vector density) satisfy a parabolic 4× 4 cross-diffusion system. The key idea of the existence proof is to work with different variables: the spin-up and spin-down densities as well as the parallel and perpendicular components of the spin-vector density with respect to the magnetization. In these variables, the diffusion matrix becomes diagonal. The proofs of the L^∞ estimates are based on Stampacchia truncation as well as Moser- and Alikakos-type iteration arguments. The monotonicity of the entropy (or free energy) is also proved. Numerical experiments in one space dimension using a finite-volume discretization indicate that the entropy decays exponentially fast to the equilibrium state. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.2461v1.pdf"}
{"id": "1312.3684", "abstract": "  The boiling of possible quark nuggets during the quark-hadron phase transition of the Universe at nonzero chemical potential is revisited within the microscopic Brueckner-Hartree-Fock approach employed for the hadron phase, using two kinds of baryon interactions as fundamental inputs. To describe the deconfined phase of quark matter, we use a recently developed quark mass density-dependent model with a fully self-consistent thermodynamic treatment of confinement. We study the baryon number limit A_ boil (above which boiling may be important) with three typical values for the confinement parameter D. It is firstly found that the baryon interaction with a softer equation of state for the hadron phase would only lead to a small increase of A_ boil. However, results depend sensitively on the confinement parameter in the quark model. Specifically, boiling might be important during the Universe cooling for a limited parameter range around D^1/2 = 170 MeV, a value satisfying recent lattice QCD calculations of the vacuum chiral condensate, while for other choices of this parameter, boiling might not happen and cosmological quark nuggets of 10^2 < A < 10^50 could survive. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.3684v3.pdf"}
{"id": "1312.4056", "abstract": "  In this work, we present a quantum transport model for the selectivity filter in the KcsA potassium ion channel. This model is fully consistent with the fact that two conduction pathways are involved in the translocation of ions thorough the filter, and we show that the presence of a second path may actually bring advantages for the filter as a result of quantum interference. To highlight interferences and resonances in the model, we consider the selectivity filter to be driven by a controlled time-dependent external field which changes the free energy scenario and consequently the conduction of the ions. In particular, we demonstrate that the two-pathway conduction mechanism is more advantageous for the filter when dephasing in the transient configurations is lower than in the main configurations. As a matter of fact, K^+ ions in the main configurations are highly coordinated by oxygen atoms of the filter backbone and this increases noise. Moreover, we also show that, for a wide range of dephasing rates and driving frequencies, the two-pathway conduction used by the filter leads indeed to higher ionic currents when compared with the single path model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.4056v2.pdf"}
{"id": "1312.4094", "abstract": "  This paper considers identification and estimation of ceteris paribus effects of continuous regressors in nonseparable panel models with time homogeneity. The effects of interest are derivatives of the average and quantile structural functions of the model. We find that these derivatives are identified with two time periods for \"stayers\", i.e. for individuals with the same regressor values in two time periods. We show that the identification results carry over to models that allow location and scale time effects. We propose nonparametric series methods and a weighted bootstrap scheme to estimate and make inference on the identified effects. The bootstrap proposed allows uniform inference for function-valued parameters such as quantile effects uniformly over a region of quantile indices and/or regressor values. An empirical application to Engel curve estimation with panel data illustrates the results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.4094v3.pdf"}
{"id": "1312.5809", "abstract": "  The local magnetism induced by vacancies in the presence of the spin-orbital interaction is investigated based on the half-filled Kane-Mele-Hubbard model on the honeycomb lattice. Using the self-consistent mean-field theory, we find that the spin-orbital coupling will enhance the localization of the spin moments near a single vacancy. We further study the magnetic structures along the zigzag edges formed by a chain of vacancies. We find that the spin-orbital coupling tends to suppress the counter-polarized ferrimagnetic order on the upper and lower edges, because of the open of the spin-orbital gap. As a result, in the case of the balance number of sublattices, it will suppress completely this kind of ferrimagnetic order. But, for the imbalance case, a ferrimagnetic order along both edges exists because additional zero modes will not be affected by the spin-orbital coupling. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.5809v1.pdf"}
{"id": "1312.5813", "abstract": "  It is well known that direct training of deep neural networks will generally lead to poor results. A major progress in recent years is the invention of various pretraining methods to initialize network parameters and it was shown that such methods lead to good prediction performance. However, the reason for the success of pretraining has not been fully understood, although it was argued that regularization and better optimization play certain roles. This paper provides another explanation for the effectiveness of pretraining, where we show pretraining leads to a sparseness of hidden unit activation in the resulting neural networks. The main reason is that the pretraining models can be interpreted as an adaptive sparse coding. Compared to deep neural network with sigmoid function, our experimental results on MNIST and Birdsong further support this sparseness observation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.5813v2.pdf"}
{"id": "1312.5827", "abstract": "  We analyze the quantum jumps of an atom interacting with a cavity field. The strong atom- field interaction makes the cavity transmission depend on the time dependent atomic state, and we present a Hidden Markov Model description of the atomic state dynamics which is conditioned in a Bayesian manner on the detected signal. We suggest that small variations in the observed signal may be due to spatial motion of the atom within the cavity, and we represent the atomic system by a number of hidden states to account for both the small variations and the internal state jump dynamics. In our theory, the atomic state is determined in a Bayesian manner from the measurement data, and we present an iterative protocol, which determines both the atomic state and the model parameters. As a new element in the treatment of observed quantum systems, we employ a Bayesian approach that conditions the atomic state at time t on the data acquired both before and after t and we show that the state assignment by this approach is more decisive than the usual conditional quantum states, based on only earlier measurement data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.5827v2.pdf"}
{"id": "1401.1391", "abstract": "  We present an extensive analysis of transport properties in superdiffusive two dimensional quenched random media, obtained by packing disks with radii distributed according to a Lévy law. We consider transport and scaling properties in samples packed with two different procedures, at fixed filling fraction and at self-similar packing, and we clarify the role of the two procedures in the superdiffusive effects. Using the behavior of the filling fraction in finite size systems as the main geometrical parameter, we define an effective Lévy exponents that correctly estimate the finite size effects. The effective Lévy exponent rules the dynamical scaling of the main transport properties and identify the region where superdiffusive effects can be detected. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.1391v1.pdf"}
{"id": "1401.1699", "abstract": "  The study of interactions between simultaneously trapped cold ions and atoms has emerged as a new research direction in recent years. The development of ion-atom hybrid experiments has paved the way for investigating elastic, inelastic and reactive collisions between these species at very low temperatures, for exploring new cooling mechanisms of ions by atoms and for implementing new hybrid quantum systems. The present lecture reviews experimental methods, recent results and upcoming developments in this emerging field. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.1699v1.pdf"}
{"id": "1401.2103", "abstract": "  Most of the turbulent flows appearing in nature (e.g. geophysical and astrophysical flows) are subjected to strong rotation and stratification. These effects break the symmetries of classical, homogenous isotropic turbulence. In doing so, they introduce a natural decomposition of phase space in terms of wave modes and potential vorticity modes. The appearance of a new time scale associated to the propagation of waves, in addition to the eddy turnover time, increases the complexity of the energy transfers between the various scales; nonlinearly interacting waves may dominate at some scales while balanced motion may prevail at others. In the end, it is difficult to predict a priori if the energy cascades downscale as in homogeneous isotropic turbulence, upscale as expected from balanced dynamics, or follows yet another phenomenology.   In this paper, we suggest a theoretical approach based on equilibrium statistical mechanics for the ideal system, inspired from the restricted partition function formalism introduced in metastability studies. In this framework, we show analytically that in the presence of rotation, when the dynamics is restricted to the slow modes, the equilibrium energy spectrum features an infrared divergence characteristic of an inverse cascade regime, whereas this is not the case for purely stratified flows. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.2103v1.pdf"}
{"id": "1401.2913", "abstract": "  In this short review we present and discuss all the experimental information about the charged exotic charmonium states, which have been observed over the last five years. We try to understand their properties such as masses and decay widths with QCD sum rules. We describe this method, show the results and compare them with the experimental data and with other theoretical approaches. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.2913v1.pdf"}
{"id": "1401.4822", "abstract": "  We present preliminary results of the variability survey in the field of the glo bular cluster NGC 4833. We observed all 34 variable stars known in the cluster. In add ition, we have found two new SX Phoenicis stars, one new RR Lyrae star, twelve new ecli psing systems mostly of the W Ursae Majoris type, nine new variable red giants, and ten new field-stars showing irregular variations. Properties of RR Lyrae stars indicate that NGC 4833 is an Oosterhoff's type II globular cluster. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.4822v1.pdf"}
{"id": "1401.5545", "abstract": "  We analyze the Purcell relaxation rate of a superconducting qubit coupled to a resonator, which is coupled to a transmission line and pumped by an external microwave drive. Considering the typical regime of the qubit measurement, we focus on the case when the qubit frequency is significantly detuned from the resonator frequency. Surprisingly, the Purcell rate decreases when the strength of the microwave drive is increased. This suppression becomes significant in the nonlinear regime. In the presence of the microwave drive, the loss of photons to the transmission line also causes excitation of the qubit; however, the excitation rate is typically much smaller than the relaxation rate. Our analysis also applies to a more general case of a two-level quantum system coupled to a cavity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.5545v2.pdf"}
{"id": "1401.5932", "abstract": "  During the life cycle of bacterial cells the non-mixing of the two ring-shaped daughter genomes is an important prerequisite for the cell division process. Mimicking the environments inside highly crowded biological cells, we study the dynamics and statistical behaviour of two flexible ring polymers in the presence of cylindrical confinement and crowding molecules. From extensive computer simulations we determine the degree of ring-ring overlap and the number of inter-monomer contacts for varying volume fractions ϕ of crowders. We also examine the entropic de-mixing of polymer rings in the presence of mobile crowders and determine the characteristic times of the internal polymer dynamics. Effects of the ring length on ring-ring overlap are also analysed. In particular, on systematic variation of the fraction of crowding molecules a (1-ϕ)-scaling is found for the ring-ring overlap length along the cylinder axis, and a non-monotonic dependence of the 3D ring-ring contact number is predicted. Our results help to rationalise the implications of macromolecular crowding for circular DNA molecules in confined spaces inside bacteria as well as in localised cellular compartments inside eukaryotic cells. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.5932v1.pdf"}
{"id": "1401.6457", "abstract": "  A sharp and spatially extended peak in an astrophysical gamma ray spectrum would provide very strong evidence for the existence of dark matter (DM), given that there are no known astrophysical processes that could mimic such a signal. From the particle physics perspective, perhaps the simplest explanation for a gamma ray peak is internal bremsstrahlung in DM annihilation through a charged t-channel mediator eta close in mass to the DM particle chi. Since DM annihilation to quarks is already tightly constrained in this scenario, we focus here on the leptophilic case. We compute the electromagnetic anapole and dipole moments that DM acquires at 1-loop, and we find an interesting enhancement of these moments if the DM particle and the mediator are close in mass. We constrain the DM anapole and dipole moments using direct detection data, and then translate these limits into bounds on the DM annihilation cross section. Our bounds are highly competitive with those from astrophysical gamma ray searches. In the second part of the paper, we derive complementary constraints on internal bremsstrahlung in DM annihilation using LEP mono-photon data, measurements of the anomalous magnetic moments of the electron and the muon, and searches for lepton flavor violation. We also comment on the impact of the internal bremsstrahlung scenario on the hyperfine splitting of true muonium. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.6457v2.pdf"}
{"id": "1401.6882", "abstract": "  In this paper, we deal with the data-driven selection of multidimensional and possibly anisotropic bandwidths in the general framework of kernel empirical risk minimization. We propose a universal selection rule, which leads to optimal adaptive results in a large variety of statistical models such as nonparametric robust regression and statistical learning with errors in variables. These results are stated in the context of smooth loss functions, where the gradient of the risk appears as a good criterion to measure the performance of our estimators. The selection rule consists of a comparison of gradient empirical risks. It can be viewed as a nontrivial improvement of the so-called Goldenshluger-Lepski method to nonlinear estimators. Furthermore, one main advantage of our selection rule is the nondependency on the Hessian matrix of the risk, usually involved in standard adaptive procedures. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.6882v4.pdf"}
{"id": "1401.7779", "abstract": "  We report on the identification of the optical counterpart to Star1, the exotic object serendipitously discovered by Deutsch et al. in the core of the Galactic globular cluster NGC 6624. Star1 has been classified by Deutsch et al. as either a quiescent Cataclysmic Variable or a low-mass X-ray binary. Deutsch et al. proposed StarA as possible optical counterpart to this object. We used high-resolution images obtained with the Hubble Space Telescope to perform a variability analysis of the stars close to the nominal position of Star1. While no variability was detected for StarA, we found another star, here named COM_Star1, showing a clear sinusoidal light modulation with amplitude Δm_F435W 0.7 mag and orbital period of P_orb 98 min. The shape of the light curve is likely caused by strong irradiation by the primary heating one hemisphere of the companion, thus suggesting a quite hot primary. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.7779v1.pdf"}
{"id": "1401.8268", "abstract": "  This paper discusses the similarity of meshless discretizations of Peridynamics and Smooth-Particle-Hydrodynamics (SPH), if Peridynamics is applied to classical material models based on the deformation gradient. We show that the discretized equations of both methods coincide if nodal integration is used. This equivalence implies that Peridynamics reduces to an old meshless method and all instability problems of collocation-type particle methods apply. These instabilities arise as a consequence of the nodal integration scheme, which causes rank-deficiency and leads to spurious zero-energy modes. As a result of the demonstrated equivalence to SPH, enhanced implementations of Peridynamics should employ more accurate integration schemes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.8268v2.pdf"}
{"id": "1402.0817", "abstract": "  The BCS to BEC crossover in attractive Fermi systems is a prototype of weak to strong coupling evolution in many body physics. While extensive numerical results are available, and several approximate methods have been developed, most of these schemes are unsuccessful in the presence of spatial inhomogeneity. Such situations call for a real space approach that can handle large spatial scales and retain the crucial thermal fluctuations. With this in mind, we present comprehensive results of a real space auxiliary field approach to the BCS to BEC crossover in the attractive Hubbard model in two dimensions. The scheme reproduces the Hartree-Fock-Bogoliubov ground state, and leads to a T_c scale that agrees with quantum Monte Carlo estimates to within a few percent. We provide results on the T_c, amplitude and phase fluctuations, density of states, and the momentum resolved spectral function over the entire interaction and temperature window. We suggest how the method generalises successfully to the presence of disorder, trapping, and population imbalance. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.0817v1.pdf"}
{"id": "1402.3710", "abstract": "  In this paper we present a general approach to multivariate periodic wavelets generated by scaling functions of de la Vallée Poussin type. These scaling functions and their corresponding wavelets are determined by their Fourier coefficients, which are sample values of a function, that can be chosen arbitrarily smooth, even with different smoothness in each direction. This construction generalizes the one-dimensional de la Vallée Poussin means to the multivariate case and enables the construction of wavelet systems, where the set of dilation matrices for the two-scale relation of two spaces of the multiresolution analysis may contain shear and rotation matrices. It further enables the functions contained in each of the function spaces from the corresponding series of scaling spaces to have a certain direction or set of directions as their focus, which is illustrated by detecting jumps of certain directional derivatives of higher order. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.3710v2.pdf"}
{"id": "1402.3775", "abstract": "  In this paper, we propose new spectral viscosity methods based on the generalized Hermite functions for the solution of nonlinear scalar conservation laws in the whole line. It is shown rigorously that these schemes converge to the unique entropy solution by using compensated compactness arguments, under some conditions. The numerical experiments of the inviscid Burger's equation support our result, and it verifies the reasonableness of the conditions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.3775v3.pdf"}
{"id": "1402.4852", "abstract": "  We compute a large grid of photoionization models that covers a wide range of physical parameters and is representative of most of the observed PNe. Using this grid, we derive new formulae for the ionization correction factors (ICFs) of He, O, N, Ne, S, Ar, Cl, and C. Analytical expressions to estimate the uncertainties arising from our ICFs are also provided. This should be useful since these uncertainties are usually not considered when estimating the error bars in element abundances. Our ICFs are valid over a variety of assumptions such as the input metallicities, the spectral energy distribution of the ionizing source, the gas distribution, or the presence of dust grains. Besides, the ICFs are adequate both for large aperture observations and for pencil-beam observations in the central zones of the nebulae. We test our ICFs on a large sample of observed PNe that extends as far as possible in ionization, central star temperature, and metallicity, by checking that the Ne/O, S/O, Ar/O, and Cl/O ratios show no trend with the degree of ionization. Our ICFs lead to significant differences in the derived abundance ratios as compared with previous determinations, especially for N/O, Ne/O, and Ar/O. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.4852v1.pdf"}
{"id": "1402.5999", "abstract": "  To probe the nonlinear effects of photon-photon interaction in the quantum electrodynamics, we study the generation of circular polarized photons by the collision of two linearly polarized laser beams. In the framework of the Euler-Heisenberg effective Lagrangian and the Quantum Boltzmann equation for the time evolution of the density matrix of polarizations, we calculate the intensity of circular polarizations generated by the collision of two linearly polarized laser beams and estimate the rate of generation. As a result, we show that the generated circular polarization can be experimentally measured, on the basis of optical laser beams of average power KW, which are currently available in laboratories. Our study presents a valuable supplementary to other theoretical and experimental frameworks to study and measure the nonlinear effects of photon-photon interaction in the quantum electrodynamics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.5999v1.pdf"}
{"id": "1402.6075", "abstract": "  We demonstrate theoretically a large transverse magneto-optical Kerr effect (TMOKE) in subwavelength gratings consisting of alternating magneto-insulating and nonmagnetic dielectric nanostripes. The reflectivity of the grating reaches 96% at the frequencies corresponding to the maximum of the TMOKE response. The combination of a large TMOKE response and high reflectivity is important for applications in 3D imaging, magneto-optical data storage, and magnonics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.6075v1.pdf"}
{"id": "1402.6550", "abstract": "  This paper considers the maximum likelihood estimation of panel data models with interactive effects. Motivated by applications in economics and other social sciences, a notable feature of the model is that the explanatory variables are correlated with the unobserved effects. The usual within-group estimator is inconsistent. Existing methods for consistent estimation are either designed for panel data with short time periods or are less efficient. The maximum likelihood estimator has desirable properties and is easy to implement, as illustrated by the Monte Carlo simulations. This paper develops the inferential theory for the maximum likelihood estimator, including consistency, rate of convergence and the limiting distributions. We further extend the model to include time-invariant regressors and common regressors (cross-section invariant). The regression coefficients for the time-invariant regressors are time-varying, and the coefficients for the common regressors are cross-sectionally varying. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1402/1402.6550v1.pdf"}
{"id": "1403.3952", "abstract": "  The ability to fine-tune band gap and band inversion in topological materials is highly desirable for the development of novel functional devices. Here we propose that the electronic properties of a free-standing nanomembrane of topological crystalline insulator (TCI) SnTe and Pb_1-xSn_x(Se,Te) are highly tunable by engineering elastic strain and controlling membrane thickness, resulting in tunable band gap and giant piezoconductivity. Membrane thickness governs the hybridization of topological electronic states on opposite surfaces, while elastic strain can further modulate the hybridization strength by controlling the penetration length of surface states. We propose a frequency-resolved infrared photodetector using force-concentration induced inhomogeneous elastic strain in TCI nanomembrane with spatially varying width. The predicted tunable band gap accompanied by strong spin-textured electronic states will open up new avenues for fabricating piezoresistive devices, thermoelectrics, infrared detectors and energy-efficient electronic and optoelectronic devices based on TCI nanomembrane. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.3952v1.pdf"}
{"id": "1403.4331", "abstract": "  High luminosity conditions at the LHC pose many unique challenges for potential silicon based track trigger systems. One of the major challenges is data formatting, where hits from thousands of silicon modules must first be shared and organized into overlapping eta-phi trigger towers. Communication between nodes requires high bandwidth, low latency, and flexible real time data sharing, for which a full mesh backplane is a natural solution. A custom Advanced Telecommunications Computing Architecture data processing board is designed with the goal of creating a scalable architecture abundant in flexible, non-blocking, high bandwidth board to board communication channels while keeping the design as simple as possible. We have performed the first prototype board testing and our first attempt at designing the prototype system has proven to be successful. Leveraging the experience we gained through designing, building and testing the prototype board system we are in the final stages of laying out the next generation board, which will be used in the ATLAS Level-2 Fast TracKer as Data Formatter, as well as in the CMS Level-1 tracking trigger R   D for early technical demonstrations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.4331v1.pdf"}
{"id": "1403.4729", "abstract": "  The BICEP2 collaboration has recently reported a large tensor fluctuation in the cosmic microwave background, which suggests chaotic inflation models. In this letter, we reconsider the chaotic inflation model in the supergravity. We introduce a non-holomorphic shift-symmetry breaking parameter, which we expect to exist in general, and discuss its effect on the inflaton dynamics. We show that the model predicts a sizable deviation from the original chaotic inflation model and the predicted tensor fluctuation can lie between the BICEP2 result and the upper bound given by the Planck experiment with a small shift-symmetry breaking parameter. The model is characterized by only two parameters, which yields predictability and testability in future experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.4729v2.pdf"}
{"id": "1403.7239", "abstract": "  We propose several differential decoding schemes for asynchronous multi-user MIMO systems based on orthogonal space-time block codes (OSTBCs) where neither the transmitters nor the receiver has knowledge of the channel. First, we derive novel low complexity differential decoders by performing interference cancelation in time and employing different decoding methods. The decoding complexity of these schemes grows linearly with the number of users. We then present additional differential decoding schemes that perform significantly better than our low complexity decoders and outperform the existing synchronous differential schemes but require higher decoding complexity compared to our low complexity decoders. The proposed schemes work for any square OSTBC, any constant amplitude constellation, any number of users, and any number of receive antennas. Furthermore, we analyze the diversity of the proposed schemes and derive conditions under which our schemes provide full diversity. For the cases of two and four transmit antennas, we provide examples of PSK constellations to achieve full diversity. Simulation results show that our differential schemes provide good performance. To the best of our knowledge, the proposed differential detection schemes are the first differential schemes for asynchronous multi-user systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.7239v3.pdf"}
{"id": "1403.7406", "abstract": "  We propose a parsimonious stochastic model for characterising the distributional and temporal properties of rainfall. The model is based on an integrated Ornstein-Uhlenbeck process driven by the Hougaard Lévy process. We derive properties of this process and propose an extended model which generalises the Ornstein-Uhlenbeck process to the class of continuous-time ARMA (CARMA) processes. The model is illustrated by fitting it to empirical rainfall data on both daily and hourly time scales. It is shown that the model is sufficiently flexible to capture important features of the rainfall process across locations and time scales. Finally we study an application to the pricing of rainfall derivatives which introduces the market price of risk via the Esscher transform. We first give a result specifying the risk-neutral expectation of a general moving average process. Then we illustrate the pricing method by calculating futures prices based on empirical daily rainfall data, where the rainfall process is specified by our model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.7406v2.pdf"}
{"id": "1403.8056", "abstract": "  We explore the breaking of rotational symmetry on the lattice for bound state energies and practical methods for suppressing this breaking. We demonstrate the general problems associated with lattice discretization errors and finite-volume errors using an α cluster model for ^8Be and ^12C. We consider the two and three α-particle systems and focus on the lowest states with non-zero angular momentum which split into multiplets corresponding to different irreducible representations of the cubic group. We examine the dependence of such splittings on the lattice spacing and box size. We find that lattice spacing errors are closely related to the commensurability of the lattice with the intrinsic length scales of the system. We also show that rotational symmetry breaking effects can be significantly reduced by using improved lattice actions, and that the physical energy levels are accurately reproduced by the weighted average of a given spin multiplets. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.8056v1.pdf"}
{"id": "1404.0782", "abstract": "  DNA molecules spin-coated on amorphous quartz substrates are shown to form stable films. Electron density profiles (EDPs) along the film depth show that film prepared from aqueous solution of DNA exhibits layering of the molecules in three stacks parallel to the substrate whereas film prepared from counterion added solution does not have layering but have smaller thickness and enhanced surface roughness, although both films have 'liquid-like' height-height correlations. We explain these results by a model of film of a 'liquid' comprising of rod-like molecules where the counterion concentration in the liquid determines the rod length. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.0782v1.pdf"}
{"id": "1404.1409", "abstract": "  The notion of distance defined on the set of states of a composite quantum system can be used to quantify total, quantum and classical correlations in a unifying way. We provide new closed formulae for classical and total correlations of two-qubit Bell-diagonal states by considering the Bures distance. Complementing the known corresponding expressions for entanglement and more general quantum correlations, we thus complete the quantitative hierarchy of Bures correlations for Bell-diagonal states. We then explicitly calculate Bures correlations for two relevant families of states: Werner states and rank-2 Bell-diagonal states, highlighting the subadditivity which holds for total correlations with respect to the sum of classical and quantum ones when using Bures distance. Finally, we analyse a dynamical model of two independent qubits locally exposed to non-dissipative decoherence channels, where both quantum and classical correlations measured by Bures distance exhibit freezing phenomena, in analogy with other known quantifiers of correlations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.1409v3.pdf"}
{"id": "1404.2186", "abstract": "  Massive quiescent galaxies at z ≈ 2 are apparently much more compact than galaxies of comparable mass today. How robust are these size measurements? We perform comprehensive simulations to determine possible biases and uncertainties in fitting single-component light distributions to real galaxies. In particular, we examine the robustness of the measurements of the luminosity, size, and other structural parameters. We devise simulations with increasing realism to systematically disentangle effects due to the technique (specifically using GALFIT) and the intrinsic structures of the galaxies. By accurately capturing the detailed substructures of nearby elliptical galaxies and then rescaling their sizes and signal-to-noise to mimic galaxies at different redshifts, we confirm that the massive quiescent galaxies at z ≈ 2 are significantly more compact intrinsically than their local counterparts. Their observed compactness is not a result of missing faint outer light due to systematic errors in modeling. In fact, we find that fitting multi-component galaxies with a single Sérsic profile, the procedure most commonly adopted in the literature, biases the inferred sizes higher by up to 10", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.2186v2.pdf"}
{"id": "1404.2913", "abstract": "  The quasilinear premise is a hypothesis for the modeling of plasma turbulence in which the turbulent fluctuations are represented by a superposition of randomly-phased linear wave modes, and energy is transferred among these wave modes via nonlinear interactions. We define specifically what constitutes the quasilinear premise, and present a range of theoretical arguments in support of the relevance of linear wave properties even in a strongly turbulent plasma. We review evidence both in support of and in conflict with the quasilinear premise from numerical simulations and measurements of plasma turbulence in the solar wind. Although the question of the validity of the quasilinear premise remains to be settled, we suggest that the evidence largely supports the value of the quasilinear premise in modeling plasma turbulence and that its usefulness may also be judged by the insights gained from such an approach, with the ultimate goal to develop the capability to predict the evolution of any turbulent plasma system, including the spectrum of turbulent fluctuations, their dissipation, and the resulting plasma heating. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.2913v1.pdf"}
{"id": "1404.3457", "abstract": "  The Collider Detector at Fermilab (CDF) is a general-purpose experimental apparatus with an inner tracking detector for measuring charged particles, surrounded by a calorimeter for measurements of electromagnetic and hadronic showers, and a muon detector system. We present a technique for, and results of, a precise relative alignment of the drift chamber wires of the CDF tracker. This alignment has been an important component of the track momentum calibration, which is the basis for the charged-lepton calibration for the measurement of the W boson mass at CDF. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.3457v2.pdf"}
{"id": "1404.6569", "abstract": "  The application of linear kinetic treatments to plasma waves, damping, and instability requires favorable inequalities between the associated linear timescales and timescales for nonlinear (e.g., turbulence) evolution. In the solar wind these two types of timescales may be directly compared using standard Kolmogorov-style analysis and observational data. The estimated local nonlinear magnetohydrodynamic cascade times, evaluated as relevant kinetic scales are approached, remain slower than the cyclotron period, but comparable to, or faster than, the typical timescales of instabilities, anisotropic waves, and wave damping. The variation with length scale of the turbulence timescales is supported by observations and simulations. On this basis the use of linear theory - which assumes constant parameters to calculate the associated kinetic rates - may be questioned. It is suggested that the product of proton gyrofrequency and nonlinear time at the ion gyroscales provides a simple measure of turbulence influence on proton kinetic behavior. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.6569v1.pdf"}
{"id": "1404.6893", "abstract": "  We examine a model of BPS black holes lying on a discrete extra space. The geometry is obtained from the discretization of the harmonic equation. We study the scattering amplitudes of two types of scalar fields, which correspond to fields in a bulk and on a brane. We conclude that the two types of scattering can be distinguished in the region of large transfer momentum. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.6893v2.pdf"}
{"id": "1404.7610", "abstract": "  A chordless cycle (induced cycle) C of a graph is a cycle without any chord, meaning that there is no edge outside the cycle connecting two vertices of the cycle. A chordless path is defined similarly. In this paper, we consider the problems of enumerating chordless cycles/paths of a given graph G=(V,E), and propose algorithms taking O(|E|) time for each chordless cycle/path. In the existing studies, the problems had not been deeply studied in the theoretical computer science area, and no output polynomial time algorithm has been proposed. Our experiments showed that the computation time of our algorithms is constant per chordless cycle/path for non-dense random graphs and real-world graphs. They also show that the number of chordless cycles is much smaller than the number of cycles. We applied the algorithm to prediction of NMR (Nuclear Magnetic Resonance) spectra, and increased the accuracy of the prediction. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.7610v1.pdf"}
{"id": "1405.0001", "abstract": "  The nonlocal coupling effect between a one-dimensional waveguide (1DW) and a side optical cavity (SOC) is studied. We first find the real-space Hamiltonian of the nonlocal-coupling system of the 1DW and SOC, and then derive out an equation determining the energy of the hybridization state between the 1DW and SOC modes and an analytic formula for the single-photon transmission. Through them, we recognize that the single-photon transmission-dip position can be changed by adjusting the SOC size and the coupling strength between the 1DW and SOC. The transmission spectra strongly depends on the nonlocal-coupling function between the 1DW and SOC, and holds an asymmetry line shape. At last, we simulate the asymmetry of the single-photon transmission by a gold-based waveguide coupled with a rectangular SOC. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.0001v1.pdf"}
{"id": "1405.1722", "abstract": "  Most Milky Way globular clusters (GCs) exhibit measurable flattening, even if on a very low level. Both cluster rotation and tidal fields are thought to cause this flattening. Nevertheless, rotation has only been confirmed in a handful of GCs, based mostly on individual radial velocities at large radii. We are conducting a survey of the central kinematics of Galactic GCs using the new Integral Field Unit instrument VIRUS-W. We detect rotation in all 11 GCs that we have observed so far, rendering it likely that a large majority of the Milky Way GCs rotate. We use published catalogs of the ACS survey of GCs to derive central ellipticities and position angles. We show that in all cases where the central ellipticity permits an accurate measurement of the position angle, those angles are in excellent agreement with the kinematic position angles that we derive from the VIRUS-W velocity fields. We find an unexpected tight correlation between central rotation and outer ellipticity, indicating that rotation drives flattening for the objects in our sample. We also find a tight correlation between central rotation and published values for the central velocity dispersion, most likely due to rotation impacting the old dispersion measurements. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.1722v1.pdf"}
{"id": "1405.5623", "abstract": "  Discrete choice models describe the choices made by decision makers among alternatives and play an important role in transportation planning, marketing research and other applications. The mixed multinomial logit (MMNL) model is a popular discrete choice model that captures heterogeneity in the preferences of decision makers through random coefficients. While Markov chain Monte Carlo methods provide the Bayesian analogue to classical procedures for estimating MMNL models, computations can be prohibitively expensive for large datasets. Approximate inference can be obtained using variational methods at a lower computational cost with competitive accuracy. In this paper, we develop variational methods for estimating MMNL models that allow random coefficients to be correlated in the posterior and can be extended easily to large-scale datasets. We explore three alternatives: (1) Laplace variational inference, (2) nonconjugate variational message passing and (3) stochastic linear regression. Their performances are compared using real and simulated data. To accelerate convergence for large datasets, we develop stochastic variational inference for MMNL models using each of the above alternatives. Stochastic variational inference allows data to be processed in minibatches by optimizing global variational parameters using stochastic gradient approximation. A novel strategy for increasing minibatch sizes adaptively within stochastic variational inference is proposed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.5623v4.pdf"}
{"id": "1405.6253", "abstract": "  In this paper, we study the prospects for determining the nature of neutrinos in the context of a supersymmetric B-L extension of the standard model by using dark matter indirect detection signals and bounds on N_eff from the cosmic microwave background data. The model contains two new dark matter candidates whose dominant annihilation channels produce more neutrinos than neutralino dark matter in the minimal supersymmetric standard model. The photon and neutrino counts may then be used to discriminate between the two models. If the dark matter comes from the B-L sector, its indirect signals and impact on the cosmic microwave background can shed light on the nature of the neutrinos. When the light neutrinos are of Majorana type, the indirect neutrino signal from the Sun and the galactic center may show a prompt neutrino box-feature, as well as an earlier cut-off in both neutrino and gamma ray energy spectra. When the light neutrinos are of Dirac type, their contribution to the effective number of neutrinos N_eff is at a detectable level. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.6253v1.pdf"}
{"id": "1405.7243", "abstract": "  The magnetised Iron CALorimeter detector (ICAL), proposed to be built at the India-based Neutrino Observatory (INO), is designed to study atmospheric neutrino oscillations. The ICAL detector is optimized to measure the muon momentum, its direction and charge. A GEANT4-based package has been developed by the INO collaboration to simulate the ICAL geometry and propagation of particles through the detector. The simulated muon tracks are reconstructed using the Kalman Filter algorithm. Here we present the first study of the response of the ICAL detector to muons using this simulations package to determine the muon momentum and direction resolutions as well as their reconstruction and charge identification efficiencies. For 1-20 GeV/c muons in the central region of the detector, we obtain an average angle-dependent momentum resolution of 9-14", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.7243v1.pdf"}
{"id": "1405.7472", "abstract": "  Toward a test of parity violation in a gravity theory, possible effects of Chern-Simons (CS) gravity on an interferometer have been recently discussed. Continuing work initiated in an earlier publication [Okawara, Yamada and Asada, Phys. Rev. Lett. 109, 231101 (2012)], we study possible altitudinal and directional dependence of relativistic Sagnac effect in CS modified gravity. We compare the CS effects on Sagnac interferometers with the general relativistic Lense-Thirring (LT) effects. Numerical calculations show that the eastbound Sagnac interferometer might be preferred for testing CS separately, because LT effects on this interferometer cancel out. The size of the phase shift induced in the CS model might have an oscillatory dependence also on the altitude of the interferometer through the CS mass parameter m_CS. Therefore, the international space station site as well as a ground-based experiment is also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.7472v2.pdf"}
{"id": "1406.1042", "abstract": "  We present results from microscopic mode coupling theory generalized to colloidal dispersions under shear in an integration-through-transients formalism. Stress-strain curves in start-up shear, flow curves, and normal stresses are calculated with the equilibrium static structure factor as only input. Hard spheres close to their glass transition are considered, as are hard spheres with a short-ranged square-well attraction at their attraction dominated glass transition. The consequences of steric packing and physical bond formation on the linear elastic response, the stress release during yielding, and the steady plastic flow are discussed and compared to experimental data from concentrated model dispersions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.1042v1.pdf"}
{"id": "1406.2236", "abstract": "  A pattern of deviations in coupling constants of Standard Model (SM)-like Higgs boson from their SM predictions indicates characteristics of an extended Higgs sector. In particular, Yukawa coupling constants can deviate in different patterns in four types of Two Higgs Doublet Models (THDMs) with a softly-broken Z_2 symmetry. We can discriminate types of THDMs by measuring the pattern of these deviations. We calculate Yukawa coupling constants of the SM-like Higgs boson with radiative corrections in all types of Yukawa interactions in order to compare to future precision data at the International Linear Collider (ILC). We perform numerical computations of scale factors, and evaluate differences between the Yukawa couplings in THDMs and those of the SM at the one-loop level. We find that scale factors in different types of THDMs do not overlap each other even in the case with maximum radiative corrections if gauge couplings are different from the SM predictions large enough to be measured at the ILC. Therefore, in such a case, we can indirectly determine the type of the THDM at the ILC even without finding additional Higgs bosons directly. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.2236v1.pdf"}
{"id": "1406.2427", "abstract": "  Motion of randomly-driven quantum nonlinear pendulum is considered. Utilizing one-step Poincaré map, we demonstrate that classical phase space corresponding to a single realization of the random perturbation involves domains of finite-time stability. Statistical analysis of the finite-time evolution operator (FTEO) is carried out in order to study influence of finite-time stability on quantum dynamics. It is shown that domains of finite-time stability give rise to ordered patterns in distributions of FTEO eigenfunctions. Transition to global chaos is accompanied by smearing of these patterns; however, some of their traces survive on relatively long timescales. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.2427v2.pdf"}
{"id": "1406.4375", "abstract": "  STREGA (STRucture and Evolution of the GAlaxy) is a Guaranteed Time survey being performed at the VST (the ESO VLT Survey Telescope) to map about 150 square degrees in the Galactic halo, in order to constrain the mechanisms of galactic formation and evolution. The survey is built as a five-year project, organized in two parts: a core program to explore the surrounding regions of selected stellar systems and a second complementary part to map the southern portion of the Fornax orbit and extend the observations of the core program. The adopted stellar tracers are mainly variable stars (RR Lyraes and Long Period Variables) and Main Sequence Turn-off stars for which observations in the g,r,i bands are obtained. We present an overview of the survey and some preliminary results for three observing runs that have been completed. For the region centered on ω Cen (37 deg^2), covering about three tidal radii, we also discuss the detected stellar density radial profile and angular distribution, leading to the identification of extratidal cluster stars. We also conclude that the cluster tidal radius is about 1.2 deg, in agreement with values in the literature based on the Wilson model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.4375v2.pdf"}
{"id": "1406.6755", "abstract": "  Steplength thresholds for invariance preserving of three types of discretization methods on a polyhedron are considered. For Taylor approximation type discretization methods we prove that a valid steplength threshold can be obtained by finding the first positive zeros of a finite number of polynomial functions. Further, a simple and efficient algorithm is proposed to numerically compute the steplength threshold. For rational function type discretization methods we derive a valid steplength threshold for invariance preserving, which can be computed by using an analogous algorithm as in the first case. The relationship between the previous two types of discretization methods and the forward Euler method is studied. Finally, we show that, for the forward Euler method, the largest steplength threshold for invariance preserving can be computed by solving a finite number of linear optimization problems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.6755v2.pdf"}
{"id": "1406.7134", "abstract": "  We study synchronization of two dissipatively coupled Van der Pol oscillators in the quantum regime. Due to quantum noise strict frequency locking is absent and is replaced by a crossover from weak to strong frequency entrainment. We discuss the differences to the behavior of one quantum Van der Pol oscillator subject to an external drive. Moreover, we describe a possible experimental realization of two coupled quantum van der Pol oscillators in an optomechanical setting. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.7134v1.pdf"}
{"id": "1407.0624", "abstract": "  We propose a computationally feasible estimator for the needlet trispectrum, which develops earlier work on the bispectrum by Donzelli et al. (2012). Our proposal seems to enjoy a number of useful properties, in particular a) the construction exploits the localization properties of the needlet system, and hence it automatically handles masked regions; b) the procedure incorporates a quadratic correction term to correct for the presence of instrumental noise and sky-cuts; c) it is possible to provide analytic results on its statistical properties, which can serve as a guidance for simulations. The needlet trispectrum we present here provides the natural building blocks for the efficient estimation of nonlinearity parameters on CMB data, and in particular for the third order constants g_NL and τ_NL. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.0624v1.pdf"}
{"id": "1407.0881", "abstract": "  The presence of multiple fields during inflation might seed a detectable amount of non-Gaussianity in the curvature perturbations, which in turn becomes observable in present data sets like the cosmic microwave background (CMB) or the large scale structure (LSS). Within this proceeding we present a fully analytic method to infer inflationary parameters from observations by exploiting higher-order statistics of the curvature perturbations. To keep this analyticity, and thereby to dispense with numerically expensive sampling techniques, a saddle-point approximation is introduced whose precision has been validated for a numerical toy example. Applied to real data, this approach might enable to discriminate among the still viable models of inflation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.0881v1.pdf"}
{"id": "1407.1372", "abstract": "  The need to estimate a positive definite solution to an overdetermined linear system of equations with multiple right hand side vectors arises in several process control contexts. The coefficient and the right hand side matrices are respectively named data and target matrices. A number of optimization methods were proposed for solving such problems, in which the data matrix is unrealistically assumed to be error free. Here, considering error in measured data and target matrices, we present an approach to solve a positive definite constrained linear system of equations based on the use of a newly defined error function. To minimize the defined error function, we derive necessary and sufficient optimality conditions and outline a direct algorithm to compute the solution. We provide a comparison of our proposed approach and two existing methods, the interior point method and a method based on quadratic programming. Two important characteristics of our proposed method as compared to the existing methods are computing the solution directly and considering error both in data and target matrices. Moreover, numerical test results show that the new approach leads to smaller standard deviations of error entries and smaller effective rank as desired by control problems. Furthermore, in a comparative study, using the Dolan-Moré performance profiles, we show the approach to be more efficient. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.1372v2.pdf"}
{"id": "1407.1533", "abstract": "  We research a combinatorial game based on the Cookie Monster problem called the Cookie Monster game that generalizes the games of Nim and Wythoff. We also propose several combinatorial games that are in between the Cookie Monster game and Nim. We discuss properties of P-positions of all of these games.   Each section consists of two parts. The first part is a story presented from the Cookie Monster's point of view, the second part is a more abstract discussion of the same ideas by the authors. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.1533v1.pdf"}
{"id": "1407.2589", "abstract": "  A long-duration gamma-ray burst (GRB) marks the violent end of a massive star. GRBs are rare in the universe, and their progenitor stars are thought to possess unique physical properties such as low metal content and rapid rotation, while the supernovae (SNe) that are associated with GRBs are expected to be highly aspherical. To date, it has been unclear whether GRB-SNe could be used as standardizable candles, with contrasting conclusions found by different teams. In this paper I present evidence that GRB-SNe have the potential to be used as standardizable candles, and show that a statistically significant relation exists between the brightness and width of their decomposed light curves relative to a template supernova. Every single nearby spectroscopically identified GRB-SN, for which the rest-frame and host contributions have been accurately determined, follows this relation. Additionally, it is shown that not only GRB-SNe, but perhaps all supernovae whose explosion is powered by a central engine, may eventually be used as a standardizable candle. Finally, I suggest that the use of GRB-SNe as standardizable candles likely arises from from a combination of the viewing angle and similar explosion geometry in each event, the latter which is influenced by the explosion mechanism of GRB-SNe. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.2589v2.pdf"}
{"id": "1407.3042", "abstract": "  An error analysis of trigonometric integrators (or exponential integrators) applied to spatial semi-discretizations of semilinear wave equations with periodic boundary conditions in one space dimension is given. In particular, optimal second-order convergence is shown requiring only that the exact solution is of finite energy. The analysis is uniform in the spatial discretization parameter. It covers the impulse method which coincides with the method of Deuflhard and the mollified impulse method of García-Archilla, Sanz-Serna     Skeel as well as the trigonometric methods proposed by Hairer     Lubich and by Grimm     Hochbruck. The analysis can also be used to explain the convergence behaviour of the Störmer-Verlet/leapfrog discretization in time. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.3042v3.pdf"}
{"id": "1407.3400", "abstract": "  The Colorado Upper-Division Electrostatics (CUE) Diagnostic is an exam developed as part of the curriculum reform at the University of Colorado, Boulder (CU). It was designed to assess conceptual learning within upper-division electricity and magnetism (E   M). Using the CUE, we have been documenting students' understanding of E   M at Oregon State University (OSU) over a period of 5 years. Our analysis indicates that the CUE identifies concepts that are generally difficult for students, regardless of the curriculum. The overall pattern of OSU students' scores reproduces the pattern reported by Chasteen et al. at CU. There are, however, some important differences that we will address. In particular, our students struggle with the CUE problems involving separation of variables and boundary conditions. We will discuss the possible causes for this, as well as steps that may rectify the situation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.3400v2.pdf"}
{"id": "1407.4723", "abstract": "  Preliminary report on network based keyword extraction for Croatian is an unsupervised method for keyword extraction from the complex network. We build our approach with a new network measure the node selectivity, motivated by the research of the graph based centrality approaches. The node selectivity is defined as the average weight distribution on the links of the single node. We extract nodes (keyword candidates) based on the selectivity value. Furthermore, we expand extracted nodes to word-tuples ranked with the highest in/out selectivity values. Selectivity based extraction does not require linguistic knowledge while it is purely derived from statistical and structural information en-compassed in the source text which is reflected into the structure of the network. Obtained sets are evaluated on a manually annotated keywords: for the set of extracted keyword candidates average F1 score is 24,63", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.4723v1.pdf"}
{"id": "1407.4870", "abstract": "  This paper presents power coordination, power generation, and power flow control schemes for supply-demand balance in distributed grid networks. Consensus schemes using only local information are employed to generate power coordination, power generation and power flow control signals. For the supply-demand balance, it is required to determine the amount of power needed at each distributed power node. Also due to the different power generation capacities of each power node, coordination of power flows among distributed power resources is essentially required. Thus, this paper proposes a decentralized power coordination scheme, a power generation, and a power flow control method considering these constraints based on distributed consensus algorithms. Through numerical simulations, the effectiveness of the proposed approaches is illustrated. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.4870v1.pdf"}
{"id": "1407.5051", "abstract": "  We show that double mills are more stable than single mills under stochastic perturbations in swarming dynamic models with basic attraction-repulsion mechanisms. In order to analyse accurately this fact, we will present a numerical technique for solving kinetic mean field equations for swarming dynamics. Numerical solutions of these equations for different sets of parameters will be presented and compared to microscopic and macroscopic results. As a consequence, we numerically observe a phase transition diagram in term of the stochastic noise going from single to double mill for small stochasticity fading gradually to disordered states when the noise strength gets larger. This bifurcation diagram at the inhomogeneous kinetic level is shown by carefully computing the distribution function in velocity space. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.5051v1.pdf"}
{"id": "1407.6289", "abstract": "  The Axelrod model is a spatial stochastic model for the dynamics of cultures that includes two key social mechanisms: homophily and social influence, respectively defined as the tendency of individuals to interact more frequently with individuals who are more similar and the tendency of individuals to become more similar when they interact. The original model assumes that individuals are located on the vertex set of an interaction network and are characterized by their culture, a vector of opinions about F cultural features, each of which offering the same number q of alternatives. Pairs of neighbors interact at a rate proportional to the number of cultural features for which they agree, which results in one more agreement between the two neighbors. In this article, we study a more general and more realistic version of the standard Axelrod model that allows for a variable number of opinions across cultural features, say q_i possible alternatives for the ith cultural feature. Our main result shows that the one-dimensional system with two cultural features fixates when q_1 + q_2 ≥ 6. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.6289v1.pdf"}
{"id": "1407.6315", "abstract": "  Particle swarm optimization is used in several combinatorial optimization problems. In this work, particle swarms are used to solve quadratic programming problems with quadratic constraints. The approach of particle swarms is an example for interior point methods in optimization as an iterative technique. This approach is novel and deals with classification problems without the use of a traditional classifier. Our method determines the optimal hyperplane or classification boundary for a data set. In a binary classification problem, we constrain each class as a cluster, which is enclosed by an ellipsoid. The estimation of the optimal hyperplane between the two clusters is posed as a quadratically constrained quadratic problem. The optimization problem is solved in distributed format using modified particle swarms. Our method has the advantage of using the direction towards optimal solution rather than searching the entire feasible region. Our results on the Iris, Pima, Wine, and Thyroid datasets show that the proposed method works better than a neural network and the performance is close to that of SVM. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.6315v1.pdf"}
{"id": "1407.7893", "abstract": "  The Gemini Planet Imager (GPI) entered on-sky commissioning and had its first-light at the Gemini South (GS) telescope in November 2013. GPI is an extreme adaptive optics (XAO), high-contrast imager and integral-field spectrograph dedicated to the direct detection of hot exo-planets down to a Jupiter mass. The performance of the apodized pupil Lyot coronagraph depends critically upon the residual wavefront error (design goal of 60 nm RMS with 5 mas RMS tip/tilt), and therefore is most sensitive to vibration (internal or external) of Gemini's instrument suite. Excess vibration can be mitigated by a variety of methods such as passive or active dampening at the instrument or telescope structure or Kalman filtering of specific frequencies with the AO control loop. Understanding the sources, magnitudes and impact of vibration is key to mitigation. This paper gives an overview of related investigations based on instrument data (GPI AO module) as well as external data from accelerometer sensors placed at different locations on the GS telescope structure. We report the status of related mitigation efforts, and present corresponding results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1407/1407.7893v1.pdf"}
{"id": "1408.0604", "abstract": "  Voigt wave propagation was investigated in a homogenized composite material (HCM) arising from a porous electro–optic host material infiltrated by a fluid of refractive index n_a. The constitutive parameters of the HCM were estimated using the extended Bruggeman homogenization formalism. Numerical studies revealed that the directions which support Voigt wave propagation in the HCM could be substantially controlled by means of an applied dc electric field. Furthermore, the extent to which this control could be achieved was found to be sensitive to the porosity of the host material, the shapes, sizes and orientations of the pores, as well as the refractive index n_a. These findings may be particularly significant for potential technological applications of Voigt waves, such as in optical sensing. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.0604v1.pdf"}
{"id": "1408.0647", "abstract": "  Hilbert - Schmidt and trace norm geometric quantum discord are compared with regard to their behavior during local time evolution. We consider the system of independent two - level atoms with time evolution given by the dissipative process of spontaneous emission. It is explicitly shown that the Hilbert - Schmidt norm discord has nonphysical properties with respect to such local evolution and cannot serve as a reasonable measure of quantum correlations and the better choice is to use trace norm discord as such a measure. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.0647v1.pdf"}
{"id": "1408.1413", "abstract": "  We carried out detailed analysis of X-ray and radio observations of a simple flare loop that occurred on 12th August 2002, with the impulsive hard X-ray (HXR) light curves dominated by a single pulse. The emission spectra of the early impulsive phase are consistent with an isothermal model in the coronal loop with a temperature reaching several keVs. A power-law high-energy spectral tail is evident near the HXR peak time, in accordance with the appearance of footpoints at high energies, and is well correlated with the radio emission. The energy content of the thermal component keeps increasing gradually after the disappearance of this nonthermal component. These results suggest that electron acceleration only covers a central period of a longer and more gradual energy dissipation process and that the electron transport within the loop plays a crucial role in the formation of the inferred power-law electron distribution. The spectral index of power-law photons shows a very gradual evolution indicating a quasi-steady state of the electron accelerator, which is confirmed by radio observations. These results are consistent with the theory of stochastic electron acceleration from a thermal background. Advanced modeling with coupled electron acceleration and spatial transport processes is needed to explain these observations more quantitatively, which may reveal the dependence of the electron acceleration on the spatial structure of the acceleration region. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.1413v1.pdf"}
{"id": "1408.2703", "abstract": "  Magnetic materials for specific applications require an accurate control and complete comprehension of their magnetic properties. In particular, nanoparticles embedded in a polycrystalline matrix emerge as good candidates for applications due to the possibility of tuning the magnetic properties through interface interaction effects. Here, iron/wüstite composite is prepared using high energy mechanical milling from iron powder and water. The sample is analyzed by X-ray diffraction, dynamic laser light scattering, Mössbauer spectroscopy, field cooling and zero field cooling curves, magnetization curves, and magnetic hyperthermia. Based on the results, we identify that the produced sample is like Fe nanoparticles embedded in a wüstite matrix, with high stability in time, and shows noticeable features such as exchange bias effect at low temperatures and promising temperatures reached in a short time interval when considered magnetic hyperthermia, ∼ 46 ^∘C, becoming an interesting candidate for biological applications, such as the one employed for cancer therapy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.2703v1.pdf"}
{"id": "1408.3385", "abstract": "  Planets in close orbits around their host stars are subject to strong irradiation. High-energy irradiation, originating from the stellar corona and chromosphere, is mainly responsible for the evaporation of exoplanetary atmospheres. We have conducted multiple X-ray observations of transiting exoplanets in short orbits to determine the extent and heating of their outer planetary atmospheres. In the case of HD 189733 b, we find a surprisingly deep transit profile in X-rays, indicating an atmosphere extending out to 1.75 optical planetary radii. The X-ray opacity of those high-altitude layers points towards large densities or high metallicity. We preliminarily report on observations of the Hot Jupiter CoRoT-2 b from our Large Program with XMM-Newton, which was conducted recently. In addition, we present results on how exoplanets may alter the evolution of stellar activity through tidal interaction. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.3385v1.pdf"}
{"id": "1408.3950", "abstract": "  We explore the quantum dynamics of particles in a spatiotemporally driven lattice. A powerful numerical scheme is developed, which provides us with the Floquet modes and thus enables a stroboscopic propagation of arbitrary initial states. A detailed symmetry analysis represents the cornerstone for an intricate manipulation of the Floquet spectrum. Specifically, we show how exact crossings can be converted into avoided ones, while the width of these resulting avoided crossings can be engineered by adjusting parameters of the local driving. Asymptotic currents are shown to be controllable over a certain parameter range. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.3950v1.pdf"}
{"id": "1408.4375", "abstract": "  We present a complete theoretical treatment of Stark effects in doped silicon, whose predictions are supported by experimental measurements. A multi-valley effective mass theory, dealing non-perturbatively with valley-orbit interactions induced by a donor-dependent central cell potential, allows us to obtain a very reliable picture of the donor wave function within a relatively simple framework. Variational optimization of the 1s donor binding energies calculated with a new trial wave function, in a pseudopotential with two fitting parameters, allows an accurate match of the experimentally determined donor energy levels, while the correct limiting behavior for the electronic density, both close to and far from each impurity nucleus, is captured by fitting the measured contact hyperfine coupling between the donor nuclear and electron spin.   We go on to include an external uniform electric field in order to model Stark physics: With no extra ad hoc parameters, variational minimization of the complete donor ground energy allows a quantitative description of the field-induced reduction of electronic density at each impurity nucleus. Detailed comparisons with experimental values for the shifts of the contact hyperfine coupling reveal very close agreement for all the donors measured (P, As, Sb and Bi). Finally, we estimate field ionization thresholds for the donor ground states, thus setting upper limits to the gate manipulation times for single qubit operations in Kane-like architectures: the Si:Bi system is shown to allow for A gates as fast as around 10 MHz. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.4375v1.pdf"}
{"id": "1408.5262", "abstract": "  BAR superfamily proteins have a banana-shaped domain that causes the local bending of lipid membranes. We study as to how such a local anisotropic curvature induces effective interaction between proteins and changes the global shape of vesicles and membrane tubes using meshless membrane simulations. The proteins are modeled as banana-shaped rods strongly adhered to the membrane. Our study reveals that the rods assemble via two continuous directional phase separations unlike a conventional two-dimensional phase separation. As the rod curvature increases, in the membrane tube the rods assemble along the azimuthal direction and subsequently along the longitudinal direction accompanied by shape transformation of the tube. In the vesicle, in the addition to these two assembly processes, further increase in the rod curvature induces tubular scaffold formation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.5262v1.pdf"}
{"id": "1408.5882", "abstract": "  We report on a series of experiments with convolutional neural networks (CNN) trained on top of pre-trained word vectors for sentence-level classification tasks. We show that a simple CNN with little hyperparameter tuning and static vectors achieves excellent results on multiple benchmarks. Learning task-specific vectors through fine-tuning offers further gains in performance. We additionally propose a simple modification to the architecture to allow for the use of both task-specific and static vectors. The CNN models discussed herein improve upon the state of the art on 4 out of 7 tasks, which include sentiment analysis and question classification. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.5882v2.pdf"}
{"id": "1409.0388", "abstract": "  We investigate the effects of Rashba and intrinsic spin-orbit couplings in graphynes. First, we develop a general method to address spin-orbit couplings within the tight-binding theory. Then, we apply this method to α, β, and γ-graphyne, and determine the SOC parameters in terms of the microscopic hopping and on-site energies. We find that for α-graphyne, as in graphene, the intrinsic SOC opens a non-trivial gap, whereas the Rashba SOC splits each Dirac cone into four. In β and γ graphyne, the Rashba SOC can lead to a Lifshitz phase transition, thus transforming the zero-gap semiconductor into a gapped system or vice versa, when pairs of Dirac cones annihilate or emerge. The existence of internal (within the benzene ring) and external SOC in these compounds allow us to explore a myriad of phases not available in graphene. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1409/1409.0388v2.pdf"}
{"id": "1409.0539", "abstract": "  The Euclid space telescope will observe  10^5 strong galaxy-galaxy gravitational lens events in its wide field imaging survey over around half the sky, but identifying the gravitational lenses from their observed morphologies requires solving the difficult problem of reliably separating the lensed sources from contaminant populations, such as tidal tails, as well as presenting challenges for spectroscopic follow-up redshift campaigns. Here I present alternative selection techniques for strong gravitational lenses in both Euclid and the Square Kilometer Array, exploiting the strong magnification bias present in the steep end of the Halpha luminosity function and HI mass function. Around 10^3 strong lensing events are detectable with this method in the Euclid wide survey. While only  1", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1409/1409.0539v1.pdf"}
{"id": "1409.0581", "abstract": "  The Veltmann models, which include the Plummer and Hernquist models as special cases, are studied in the presence of a cosmological constant. Physically relevant quantities such as the velocity dispersion profiles and the anisotropy parameter are computed through the use of the self-consistent approach. The cutoff radii for these models and the mass contained within this volume are also calculated. It is shown that the inclusion of a cosmological constant leads to many observable quantities such as the surface density, dispersion profiles and the anisotropy parameter becoming increasingly modified. In some scenarios, they are easily distinguished from the case where the cosmological constant is absent, as a result of their non-monotonic behaviour. The effects of neighbouring gravitational systems on the central system are also studied, and compared against the effects arising from the cosmological constant. Consequently, it is suggested that the effects of a cosmological constant can prove to be quite important when modelling dilute collisionless systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1409/1409.0581v1.pdf"}
{"id": "1409.1875", "abstract": "  We explain in depth the previously proposed theory of the coherent Van der Waals(cVdW) interaction - the counterpart of Van der Waals (VdW) force - emerging in spatially coherently fluctuating electromagnetic fields. We show that cVdW driven matter is dominated by many body interactions, which are significantly stronger than those found in standard Van der Waals (VdW) systems. Remarkably, the leading 2- and 3-body interactions are of the same order with respect to the distance (∝ R^-6), in contrast to the usually weak VdW 3-body effects (∝ R^-9). From a microscopic theory we show that the anisotropic cVdW many body interactions drive the formation of low-dimensional structures such as chains, membranes and vesicles with very unusual, non-local properties. In particular, cVdW chains display a logarithmically growing stiffness with the chain length, while cVdW membranes have a bending modulus growing linearly with their size. We argue that the cVdW anisotropic many body forces cause local cohesion but also a negative effective \"surface tension\". We conclude by deriving the equation of state for cVdW materials and propose new experiments to test the theory, in particular the unusual 3-body nature of cVdW. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1409/1409.1875v2.pdf"}
{"id": "1409.3941", "abstract": "  Template abstract domains allow to express more interesting properties than classical abstract domains. However, template generation is a challenging problem when one uses template abstract domains for program analysis. In this paper, we relate template generation with the program properties that we want to prove. We focus on one-loop programs with nested conditional branches. We formally define the notion of well-representative template basis with respect to such programs and a given property. The definition relies on the fact that template abstract domains produce inductive invariants. We show that these invariants can be obtained by solving certain systems of functional inequalities. Then, such systems can be strengthened using a hierarchy of sum-of-squares (SOS) problems when we consider programs written in polynomial arithmetic. Each step of the SOS hierarchy can possibly provide a solution which in turn yields an invariant together with a certificate that the desired property holds. The interest of this approach is illustrated on nontrivial program examples in polynomial arithmetic. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1409/1409.3941v2.pdf"}
{"id": "1409.4031", "abstract": "  We estimate the size of a primordial black hole exploding today via a white hole transition, and the power in the resulting explosion, using a simple model. We point out that Fast Radio Bursts, strong signals with millisecond duration, probably extragalactic and having unknown source, have wavelength not far from the expected size of the exploding hole. We also discuss the possible higher energy components of the signal. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1409/1409.4031v3.pdf"}
{"id": "1409.5014", "abstract": "  We describe a constraint analysis for the interaction of the vector-meson octet with the baryon octet. Applying Dirac's Hamiltonian method, we verify that the standard interaction in terms of two independent SU(3) structures is consistent at the classical level. We argue how the requirement of self consistency with respect to perturbative renormalizability may lead to relations among the renormalized coupling constants of the system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1409/1409.5014v1.pdf"}
{"id": "1410.0943", "abstract": "  Weak values arise experimentally as conditioned averages of weak (noisy) observable measurements that minimally disturb an initial quantum state, and also as dynamical variables for reduced quantum state evolution even in the absence of measurement. These averages can exceed the eigenvalue range of the observable ostensibly being estimated, which has prompted considerable debate regarding their interpretation. Classical conditioned averages of noisy signals only show such anomalies if the quantity being measured is also disturbed prior to conditioning. This fact has recently been rediscovered, along with the question whether anomalous weak values are merely classical disturbance effects. Here we carefully review the role of the weak value as both a conditioned observable estimation and a dynamical variable, and clarify why classical disturbance models will be insufficient to explain the weak value unless they can also simulate other quantum interference phenomena. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.0943v3.pdf"}
{"id": "1410.1241", "abstract": "  A halo merger tree forms the essential backbone of a semi-analytic model for galaxy formation and evolution. Recent studies have pointed out that extracting merger trees from numerical simulations of structure formation is non-trivial; different tree building algorithms can give differing merger histories. These differences should be carefully understood before merger trees are used as input for models of galaxy formation. We investigate the impact of different halo merger trees on a semi-analytic model. We find that the z=0 galaxy properties in our model show differences between trees when using a common parameter set. The star formation history of the Universe and the properties of satellite galaxies can show marked differences between trees with different construction methods. Independently calibrating the semi-analytic model for each tree can reduce the discrepancies between the z=0 global galaxy properties, at the cost of increasing the differences in the evolutionary histories of galaxies. Furthermore, the underlying physics implied can vary, resulting in key quantities such as the supernova feedback efficiency differing by factors of 2. Such a change alters the regimes where star formation is primarily suppressed by supernovae. Therefore, halo merger trees extracted from a common halo catalogue using different, but reliable, algorithms can result in a difference in the semi-analytic model. Given the uncertainties in galaxy formation physics, however, these differences may not necessarily be viewed as significant. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.1241v1.pdf"}
{"id": "1410.2138", "abstract": "  We present a wave-function based method to solve the time-dependent many-electron Schrödinger equation (TDSE) with special emphasis on strong-field ionization phenomena. The theory builds on the configuration-interaction (CI) approach supplemented by the generalized-active-space (GAS) concept from quantum chemistry. The latter allows for a controllable reduction in the number of configurations in the CI expansion by imposing restrictions on the active orbital space. The method is similar to the recently formulated time-dependent restricted-active-space (TD-RAS) CI method [D. Hochstuhl, and M. Bonitz, Phys. Rev. A 86, 053424 (2012)]. We present details of our implementation and address convergence properties with respect to the active spaces and the associated account of electron correlation in both ground state and excitation scenarios. We apply the TD-GASCI theory to strong-field ionization of polar diatomic molecules and illustrate how the method allows us to uncover a strong correlation-induced shift of the preferred direction of emission of photoelectrons. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.2138v2.pdf"}
{"id": "1410.4332", "abstract": "  We investigate the chaoticity parameter λ in two-pion interferometry in an expanding boson gas model. The degree of Bose-Einstein condensation of identical pions, density distributions, and Hanbury-Brown-Twiss (HBT) correlation functions are calculated for the expanding gas within the mean-field description with a harmonic oscillator potential. The results indicate that a sources with thousands of identical pions may exhibit a degree of Bose-Einstein condensation at the temperatures during the hadronic phase in relativistic heavy-ion collisions. This finite condensation may decrease the chaoticity parameter λ in the two-pion interferometry measurements at low pion pair momenta, but influence only slightly the λ value at high pion pair momentum. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.4332v1.pdf"}
{"id": "1410.5225", "abstract": "  We present a study of photometric properties of very crowded stellar fields toward the Galactic Bulge. We performed a search for pulsating stars among thousands of variable stars from the OGLE-II survey supplementing the variability study with photometric measurements in four Johnson-Cousins UBVI_ C passbands. Using these data, we analysed the properties of objects located at different distances and, whenever possible, classified them. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.5225v1.pdf"}
{"id": "1410.5731", "abstract": "  The rapid development of the magnetic tunnel junction (MTJ) spin torque oscillator (STO) technology demands an analytical model to enable building MTJ STO-based circuits and systems so as to evaluate and utilize MTJ STOs in various applications. In Part I of this paper, an analytical model based on the macrospin approximation, has been introduced and verified by comparing it with the measurements of three different MTJ STOs. In Part II, the full Verilog-A implementation of the proposed model is presented. To achieve a reliable model, an approach to reproduce the phase noise generated by the MTJ STO has been proposed and successfully employed. The implemented model yields a time domain signal, which retains the characteristics of operating frequency, linewidth, oscillation amplitude and DC operating point, with respect to the magnetic field and applied DC current. The Verilog-A implementation is verified against the analytical model, providing equivalent device characteristics for the full range of biasing conditions. Furthermore, a system that includes an MTJ STO and CMOS RF circuits is simulated to validate the proposed model for system- and circuit-level designs. The simulation results demonstrate that the proposed model opens the possibility to explore STO technology in a wide range of applications. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.5731v3.pdf"}
{"id": "1410.7735", "abstract": "  We present a class of relativistic solutions of cold compact anisotropic stars in hydrostatic equilibrium in the framework of higher dimensions using spheroidal geometry. The solutions obtained with Vaidya-Tikekar metric are used to construct stellar models of compact objects and studied their physical features. The effects of anisotropy and extra dimensions on the global properties namely, compactness, mass, radius, equation of state are determined in higher dimensions in terms of the spheroidicity parameter (λ). It is noted that for a given configuration, compactness of a star is found smaller in higher dimensions compared to that in four space-time dimensions. It is also noted that the maximum mass of compact objects increase with the increase of space-time dimensions which however attains a maximum when D=5 for a large (λ=100), thereafter it decreases as one increases number of extra dimensions. The effect of extra dimensions on anisotropy is also studied. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.7735v1.pdf"}
{"id": "1410.8104", "abstract": "  The p-norm often used in stress constrained topology optimisation supposedly mimics a delta function and it is thus characterised by a small length scale and ideally one would also prefer to have the solid-void transition occur over a small length scale, since the material in this transition does not have a clear physical interpretation. We propose to resolve these small length scales using anisotropic mesh adaptation. We use the method of moving asymptotes with interpolation of sensitivities, asymptotes and design variables between iterations. We demonstrate this combination for the portal and L-bracket problems with p=10, and we are able to investigate mesh dependence. Finally, we suggest relaxing the L-bracket problem statement by introducing a rounded corner. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.8104v2.pdf"}
{"id": "1411.0876", "abstract": "  Electric quadrupole strength functions have been deduced from averages of a large number of E2 transition strengths calculated within the shell model for the nuclides ^94Mo and ^95Mo. These strength functions are at variance with phenomenological approximations as provided by the Reference Input Parameter Library RIPL-3 for calculations of reaction rates on the basis of the statistical model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1411/1411.0876v2.pdf"}
{"id": "1411.1784", "abstract": "  Generative Adversarial Nets [8] were recently introduced as a novel way to train generative models. In this work we introduce the conditional version of generative adversarial nets, which can be constructed by simply feeding the data, y, we wish to condition on to both the generator and discriminator. We show that this model can generate MNIST digits conditioned on class labels. We also illustrate how this model could be used to learn a multi-modal model, and provide preliminary examples of an application to image tagging in which we demonstrate how this approach can generate descriptive tags which are not part of training labels. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1411/1411.1784v1.pdf"}
{"id": "1411.4314", "abstract": "  This paper presents findings from a study of the email network of a large scientific research organization, focusing on methods for visualizing and modeling organizational hierarchies within large, complex network datasets. In the first part of the paper, we find that visualization and interpretation of complex organizational network data is facilitated by integration of network data with information on formal organizational divisions and levels. By aggregating and visualizing email traffic between organizational units at various levels, we derive several insights into how large subdivisions of the organization interact with each other and with outside organizations. Our analysis shows that line and program management interactions in this organization systematically deviate from the idealized pattern of interaction prescribed by \"matrix management.\" In the second part of the paper, we propose a power law model for predicting degree distribution of organizational email traffic based on hierarchical relationships between managers and employees. This model considers the influence of global email announcements sent from managers to all employees under their supervision, and the role support staff play in generating email traffic, acting as agents for managers. We also analyze patterns in email traffic volume over the course of a work week. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1411/1411.4314v1.pdf"}
{"id": "1411.4519", "abstract": "  The collective dynamics of mobile scatterers and light in optical resonators generates complex behaviour. For strong transverse illumination a phase transition from homogeneous to crystalline particle order appears. In contrast, a gas inside a single-side pumped ring cavity exhibits an instability towards bunching and collective acceleration called collective atomic recoil lasing (CARL). We demonstrate that by driving two orthogonally polarized counter propagating modes of a ring resonator one realises both cases within one system. The corresponding phase diagram depending on the two pump intensities exhibits regions in which either a generalized form of self-ordering towards a travelling density wave with constant centre of mass velocity or a CARL instability is formed. Controlling the cavity driving then allows to accelerate or slow down and trap a sufficiently dense beam of linearly polarizable particles. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1411/1411.4519v1.pdf"}
{"id": "1411.6734", "abstract": "  We study the problem of wave transport in a one-dimensional disordered system, where the scatterers of the chain are n barriers and wells with statistically independent intensities and with a spatial extension ł_c which may contain an arbitrary number δ/2π of wavelengths, where δ = k l_c. We analyze the average Landauer resistance and transmission coefficient of the chain as a function of n and the phase parameter δ. For weak scatterers, we find: i) a regime, to be called I, associated with an exponential behavior of the resistance with n, ii) a regime, to be called II, for δ in the vicinity of π, where the system is almost transparent and less localized, and iii) right in the middle of regime II, for δ very close to π, the formation of a band gap, which becomes ever more conspicuous as n increases. In regime II, both the average Landauer resistance and the transmission coefficient show an oscillatory behavior with n and δ. These characteristics of the system are found analytically, some of them exactly and some others approximately. The agreement between theory and simulations is excellent, which suggests a strong motivation for the experimental study of these systems. We also present a qualitative discussion of the results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1411/1411.6734v3.pdf"}
{"id": "1411.7701", "abstract": "  This work presents a novel method to estimate the effective opening angle of CBe star disks from projected axis ratio measurements, obtained by interferometry using Bayesian statistics. A Monte Carlo scheme was used to generate a large set of theoretical axis ratios from disk models using different distributions of disk densities and opening angles. These theoretical samples were then compared to observational samples, using a two-sample Kolmogorov-Smirnov test, to determine which theoretical distribution best reproduces the observations. The results suggest that the observed ratio distributions in the K-, H-, and N-band can best be explained by the presence of thin disks, with opening half-angles of the order of 0.15^∘ to 4.0^∘. Results for measurements over the Hα line point toward slightly thicker disks, 3.7^∘ to 14^∘, which is consistent with a flaring disk predicted by the viscous disk model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1411/1411.7701v1.pdf"}
{"id": "1412.1036", "abstract": "  We report on structures in a scale-dependent Lyapunov exponent of an experimental chaotic map that arise due to discontinuities in the map. The chaos is realized in an autonomous Boolean network which is constructed using asynchronous logic gates to form a map operator that outputs an unclocked pulse-train of varying widths. The map operator executes pulse-width stretching and folding and the operator's output is fed back to its input to continuously iterate the map. Using a simple model, we show that the structured scale-dependence in the system's Lyapunov exponent is the result of the discrete logic elements in the map operator's stretching function. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.1036v3.pdf"}
{"id": "1412.2920", "abstract": "  By means of density functional theory we have undertaken a structural, electronic and magnetic survey of the adsorption of the Fe_xPt_y(x,y=<4) clusters on MgO (001) surface under the generalized gradient approximation. We have tested different atomic adsorption geometries with the aim of scan a wider range of adsorption sites in order to determine the preferential surface covering. Our main conclusion in this respect is that the FePt wets the surface. The intracluster (before and after the adsorption) and cluster-to-surface binding mechanisms were investigated via the adsorption energy, charge transfer, density of states and hybridization analysis. The adsorption energy values increased for those geometries in which keeping the Fe or Pt atom @top-O, the outermost species was moved to cover the surface. In general the unsupported clusters present higher intracluster energies than the adsorbed ones being the average difference of 1.5 eV. In this regard there was a small reduction in the net magnetic moment of the supported clusters due to an internal and external rearrangement of the spin-up/-down charge. Furthermore, a complex and subtle charge transfer between different species takes place having an increasing the Pt and O population at the expense of the lost Fe charge. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.2920v1.pdf"}
{"id": "1412.4610", "abstract": "  We estimate the critical magnetic field strength at which the lowest or second Landau levels play an important role in the quark phase inside the hybrid stars, and show that the magnetic field should be in the order of 10^19 Gauss at the nuclear density ∼0.16 fm^-3. We also find that the pressure of quark matter settling only in the lowest Landau level can be expressed as a function of the energy density independently of the magnetic field strength, which corresponds to the causality limit of a stiff equation of state. Adiabatic index of quark matter well exceeds 4/3 in the core, and we find a possibility to construct massive hybrid star models occupied in large part by quark matter, whose maximum mass becomes larger than two solar mass. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.4610v1.pdf"}
{"id": "1412.7807", "abstract": "  We present an efficient theoretical method for calculating the time evolution of the density matrix of a multilevel quantum system weakly interacting with incoherent light. The method combines the Bloch-Redfield theory with a partial secular approximation for one-photon coherences, resulting in a master equation that explicitly exposes the reliance on transition rates and the angles between transition dipole moments in the energy basis. The modified Bloch-Redfield master equation allows an unambiguous distinction between the regimes of quantum coherent vs. incoherent energy transfer under incoherent light illumination. The fully incoherent regime is characterized by orthogonal transition dipole moments in the energy basis, leading to a dynamical evolution governed by a coherence-free Pauli-type master equation. The coherent regime requires non-orthogonal transition dipole moments in the energy basis, and leads to the generation of noise-induced quantum coherences and population-to-coherence couplings. As a first application, we consider the dynamics of excited state coherences arising under incoherent light excitation from a single ground state, and observe population-to-coherence transfer and the formation of non-equilibrium quasisteady states in the regime of small excited state splitting. Analytical expressions derived earlier for the V-type system [Phys. Rev. Lett. 113, 113601 (2014)] are found to provide a nearly quantitative description of multilevel excited-state populations and coherences in both the small- and large-molecule limits. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.7807v1.pdf"}
{"id": "1412.8150", "abstract": "  We find two new classes of exact solutions to the Einstein-Maxwell system of equations. The matter distribution satisfies a linear equation of state consistent with quark matter. The field equations are integrated by specifying forms for the measure of anisotropy and a gravitational potential which are physically reasonable. The first class has a constant potential and is regular in the stellar interior. It contains the familiar Einstein model as a limiting case and we can generate finite masses for the star. The second class has a variable potential and singularity at the centre. A graphical analysis indicates that the matter variables are well behaved. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.8150v1.pdf"}
{"id": "1412.8385", "abstract": "  We consider paradigmatic quenched disordered quantum spin models, viz., the XY spin glass and random-field XY models, and show that quenched averaged quantum correlations can exhibit the order-from-disorder phenomenon for finite-size systems as well as in the thermodynamic limit. Moreover, we find that the order-from-disorder can get more pronounced in the presence of temperature by suitable tuning of the system parameters. The effects are found for entanglement measures as well as for information-theoretic quantum correlation ones, although the former show them more prominently. We also observe that the equivalence between the quenched averages and their self-averaged cousins – for classical and quantum correlations – is related to the quantum critical point in the corresponding ordered system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.8385v1.pdf"}
{"id": "1501.00562", "abstract": "  We develop a new and systematic method for proving entropic Ricci curvature lower bounds for Markov chains on discrete sets. Using different methods, such bounds have recently been obtained in several examples (e.g., 1-dimensional birth and death chains, product chains, Bernoulli-Laplace models, and random transposition models). However, a general method to obtain discrete Ricci bounds had been lacking. Our method covers all of the examples above. In addition, we obtain new Ricci curvature bounds for zero-range processes on the complete graph. The method is inspired by recent work of Caputo, Dai Pra and Posta on discrete functional inequalities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.00562v3.pdf"}
{"id": "1501.00900", "abstract": "  An overview of tools and methods for the reconstruction of high-boost top quark decays at the LHC is given in this report. The focus is on hadronic decays, in particular an overview of the current status of top quark taggers in physics analyses is presented. The most widely used jet substructure techniques, normally used in combination with top quark taggers, are reviewed. Special techniques to treat pileup in large cone jets are described, along with a comparison of the performance of several boosted top quark reconstruction techniques. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.00900v1.pdf"}
{"id": "1501.01112", "abstract": "  We summarise the Topical Workshop on Top Quark Differential Distributions 2014, which took place in Cannes immediately before the annual Top2014 conference. The workshop was motivated by the availability of top quark differential distributions at NNLO and the forthcoming LHC 13 TeV data. The main goal of the workshop was to explore the impact of improved calculations of top quark production on precision LHC measurements, PDF determinations and searches for physics beyond the Standard Model, as well as finding ways in which the high precision data from ATLAS, CMS and LHCb can be used to further refine theoretical predictions for top production. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.01112v1.pdf"}
{"id": "1501.01607", "abstract": "  In this paper we study the relation between the light-front (infinite momentum) and rest-frame descriptions of quarkonia. While the former is more convenient for high-energy production, the latter is usually used for the evaluation of charmonium properties. In particular, we discuss the dynamics of a relativistically moving system with nonrelativistic internal motion and give relations between rest frame and light-front potentials used for the description of quarkonium states. We consider two approximations, first the small coupling regime, and next the nonperturbative small binding energy approximation. In both cases we get consistent results. Our results could be relevant for the description of final state interactions in a wide class of processes, including quarkonium production on nuclei and plasma. Moreover, they can be extended to the description of final state interactions in the production of weakly bound systems, such as for example the deuteron. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.01607v1.pdf"}
{"id": "1501.01653", "abstract": "  We discuss ergodicity breaking in frustrated disordered systems with no apparent broken symmetry of the Hamiltonian and present a way how to amend it in the low-temperature phase. We demonstrate this phenomenon on mean-field models of spin glasses. We use replicas of the spin variables to test thermodynamic homogeneity of ergodic equilibrium systems. We show that replica-symmetry breaking reflects ergodicity breaking and is used to restore an ergodic state. We then present explicit asymptotic solutions for the Ising, Potts and p-spin glasses. Each of the models shows a different low-temperature behavior and the way the replica symmetry and ergodicity are broken. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.01653v1.pdf"}
{"id": "1501.01686", "abstract": "  This paper is a major revision of our previous work on the HST model of inflation. We identify the local fluctuations of the metric with fluctuations of the mass and angular momentum of black holes, and show that the consistency conditions in HST for a single trajectory to see more and more of a homogeneous distribution of black holes, imply that the system outside the horizon is undergoing inflation: small systems of equal entropy, are not in causal contact. Homogeneity then requires that the initial trajectory underwent inflation that expanded the black hole radius into our current horizon. The low entropy of the initial state of the universe is explained by the fact that this is the maximal entropy state, which has long lived localized excitations, and which can form structures more complex than black holes. The number of e-folds, reheat temperature of the universe and size of inflationary fluctuations are calculated in terms of a few parameters. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.01686v2.pdf"}
{"id": "1501.01709", "abstract": "  In the solar neighborhood, where the typical relaxation timescale is larger than the cosmic age, at least 10% to 15% of Sun-like stars have planetary systems with Jupiter-mass planets. In contrast, dense star clusters, charactered by frequent close encounters, have been found to host very few planets. We carry out numerical simulations with different initial conditions to investigate the dynamical stability of planetary systems in star cluster environments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.01709v2.pdf"}
{"id": "1501.02657", "abstract": "  Motivated by a recent experimental observation of a complex magnetic structure [Takada et al. 2013 J. Magn. Magn. Mater. 329 95] we present a theoretical study of the magnetic structure of an Fe monolayer deposited on Rh(001). We use a classical spin Hamiltonian with parameters obtained from ab initio calculations and go beyond the usual anisotropic Heisenberg model by including isotropic biquadratic interactions. Zero-temperature Landau–Lifshitz–Gilbert spin dynamics simulations lead to a complex collinear spin configuration that, however, contradicts experimental finding. We thus conclude that higher order multi-spin interactions are likely needed to account for the magnetic ordering of the system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.02657v1.pdf"}
{"id": "1501.04300", "abstract": "  In many cases the correct theoretical description of flexoelectricity requires the consideration of the finite size of a body and is reduced to the solution of boundary problems for partial differential equations. Generally speaking, in this case one should solve jointly the equations of polarization equilibrium and equations of elastic equilibrium. However, due to the fact that typically flexoelectric moduli are very small, usually one can consider the solution of polarization equilibrium equations at a given elastic strain (direct flexoelectric effect) or the solution of elastic equilibrium equations at given polarization (converse flexoelectric effect). Derivation of the polarization equilibrium equations and boundary conditions for them can be made in the quite usual way. Solution of these equations usually is not too difficult problem. On the contrary description of converse flexoelectric effect is more complicated problem. Inter alia effective solution of corresponded boundary problems requires the development of special mathematical methods. The subject of this paper is a detailed discussion of the relevant theory focuses on the converse flexoelectric effect. It is also considered some particular examples illustrating the application of the general theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1501/1501.04300v1.pdf"}
{"id": "1502.01741", "abstract": "  This article studies the existence of long-time solutions to the Hamiltonian boundary value problem, and their consistent numerical approximation. Such a boundary value problem is, for example, common in Molecular Dynamics, where one aims at finding a dynamic trajectory that joins a given initial state with a final one, with the evolution being governed by classical (Hamiltonian) dynamics. The setting considered here is sufficiently general so that long time transition trajectories connecting two configurations can be included, provided the total energy E is chosen suitably. In particular, the formulation presented here can be used to detect transition paths between two stable basins and thus to prove the existence of long-time trajectories. The starting point is the formulation of the equation of motion of classical mechanics in the framework of Jacobi's principle; a curve shortening procedure inspired by Birkhoff's method is then developed to find geodesic solutions. This approach can be viewed as a string method. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.01741v2.pdf"}
{"id": "1502.04199", "abstract": "  We study the contribution of new sets of two-loop Barr-Zee type diagrams to the anomalous magnetic moment of the muon within the two-Higgs-doublet model framework. We show that some of these contributions can be quite sizeable for a large region of the parameter space and can significantly reduce, and in some cases even explain, the discrepancy between the theoretical prediction and the experimentally measured value of this observable. Analytical expressions are given for all the calculations performed in this work. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.04199v3.pdf"}
{"id": "1502.04554", "abstract": "  Transport properties of dense liquid helium under the conditions of planet's core and cool atmosphere of white dwarfs have been investigated by using the improved centroid path-integral simulations combined with density functional theory. The self-diffusion is largely higher and the shear viscosity is notably lower predicted with the quantum mechanical description of the nuclear motion compared with the description by Newton equation. The results show that nuclear quantum effects (NQEs), which depends on the temperature and density of the matter via the thermal de Broglie wavelength and the ionization of electrons, are essential for the transport properties of dense liquid helium at certain astrophysical conditions. The Stokes-Einstein relation between diffusion and viscosity in strongly coupled regime is also examined to display the influences of NQEs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.04554v1.pdf"}
{"id": "1502.04783", "abstract": "  We report our discovery of orbitally modulated γ-ray emission from the black widow system PSR J1311-3430. We analyze the Fermi Large Area Telescope data during the offpulse phase interval of the pulsar, and find the orbital modulation signal at a ∼3σ confidence level. Further spectral analysis shows no significant differences for the spectra obtained during the bright and faint orbital phase ranges. A simple sinusoid-like function can describe the modulation. Given these properties, we suggest that the intrabinary γ-ray emission arises from the region close to the companion and the modulation is caused by the occultation of the emitting region by the companion, similar to that is seen in the transitional millisecond pulsar binary (MSP) PSR J1023+0038. Considering the X-ray detection of intrabinary shock emission from eclipsing MSP binaries recently reported, this discovery further suggests the general existence of intrabinary γ-ray emission from them. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.04783v2.pdf"}
{"id": "1502.04913", "abstract": "  Three-body nuclear reactions in two-nucleon plus core systems are described in the framework of exact scattering equations including the core excitation. A nucleon-core optical potential is constructed that can be easily adjusted to the reference potential and thereby to the experimental two-body data, if available. This constitutes an important improvement over the simple deformation of the potential used previously that violated the original fit to the data. Predictions for elastic, inelastic, and transfer reactions involving ^10Be and ^24Mg nuclear cores are obtained. The new optical potential leads to a moderate increase of cross sections. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.04913v1.pdf"}
{"id": "1502.05452", "abstract": "  Gaussian Klauder coherent states are discussed in the context of the infinite well quantum model, otherwise known as the particle in a box. A supersymmetric partner system is also presented, as well as a construction of coherent states in this new system. We show that these states can be chosen, in both systems to have many properties usually expected for coherent states. In particular, they yield highly localised wave packets for a short period of time, which evolve in a quasi-classical manner and which saturate approximately Heisenberg uncertainty relation. These studies are elaborated in one- and two-dimensional contexts. Finally, some relations are established between the gaussian states being mostly used here and the generalised coherent states, which are more standardly found in the literature. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.05452v2.pdf"}
{"id": "1502.05705", "abstract": "  We study numerically the influence of disorder and localization effects on the local spectroscopic characteristics and infrared optical properties of _1-x_x. We treat the band structure and disorder effects at an equal level by using exact diagonalization supercell simulation method. This method accurately describes the low doping limit and gives a clear picture of the transition to higher dopings, which captures the localization effects inaccessible to other theoretical methods commonly used. Our simulations capture the rich mid-gap localized states observed in scanning tunneling microscopy studies and reproduce the observed features of the infrared optical absorption experiments. We show clear evidence of a disordered valence band model for metallic samples in which (i) there is no impurity band detached from the valence band, (ii) the disorder tends to localize and pull states near the top of the valence band into the gap region, and (iii) the Fermi energy is located deep in the delocalized region away from the mobility edge. We identify localized states deep in the gap region by visualizing the probability distribution of the quasiparticles and connecting it to their respective participation ratios. The analysis of the infrared-optical absorption data indicates that it does not have a direct relation to the nature of the states at the Fermi energy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.05705v1.pdf"}
{"id": "1503.01490", "abstract": "  Ninety eight one-dimensional channels defined using split gates fabricated on a GaAs/AlGaAs heterostructure are measured during one cooldown at 1.4 K. The devices are arranged in an array on a single chip, and individually addressed using a multiplexing technique. The anomalous conductance feature known as the \"0.7 structure\" is studied using statistical techniques. The ensemble of data show that the 0.7 anomaly becomes more pronounced and occurs at lower values as the curvature of the potential barrier in the transport direction decreases. This corresponds to an increase in the effective length of the device. The 0.7 anomaly is not strongly influenced by other properties of the conductance related to density. The curvature of the potential barrier appears to be the primary factor governing the shape of the 0.7 structure at a given T and B. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.01490v2.pdf"}
{"id": "1503.02469", "abstract": "  We develop and analyze a theoretical model to study p-wave Feshbach resonances of identical fermions in atomic waveguides by extending the two-channel model of A.D. Lange et. al. [Phys. Rev. A 79, 013622 (2009)] and S. Saeidian et. al. [Phys. Rev. A 86, 062713 (2012)]. The experimentally known parameters of Feshbach resonances in free space are used as input of the model. We calculate the shifts and widths of p-wave magnetic Feshbach resonance of ^40K atoms emerging in harmonic waveguides as p-wave confinement induced resonance (CIR). Particularly, we show a possibility to control the width and shift of the p-wave confinement induced resonance by the trap frequency and the applied magnetic field which could be used in corresponding experiments. Our analysis also demonstrates the importance of the inclusion of the effective radius in the computational schemes for the description of the p-wave CIRs contrary to the case of s-wave CIRs where the influence of this term is negligible. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.02469v1.pdf"}
{"id": "1503.02976", "abstract": "  In this review, we describe how high resolution near infrared spectroscopy and spectro-astrometry have been used to study the disks around Herbig Ae/Be stars. We show how these tools can be used to identify signposts of planet formation and elucidate the mechanism by which Herbig Ae/Be stars accrete. We also highlight some of the artifacts that can complicate the interpretation of spectro-astrometric measurements and discuss best practices for mitigating these effects. We conclude with a brief discussion of the value of long term monitoring of these systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.02976v1.pdf"}
{"id": "1503.04506", "abstract": "  ADASS has been a successful conference series for 24 years. If it is to continue to be successful and relevant we need to ensure that it provides what we as a community need from an annual conference. Earlier this year the ADASS Program Organising Committee conducted a survey on the content, style and governance of ADASS, in order to ascertain the conference needs of our community of astronomy software, methods and algorithms providers and users. 140 people participated in the survey: familiar faces, newcomers and a significant number of people who have yet to attend an ADASS.   We summarise the Birds of a Feather session held on 7 October 2014, which discussed the findings of the survey and the shape that the community would like future ADASS meetings to take: What do we like of the current format? What would we change? What can we do to make ADASS fit our current and future needs? If we are to ensure that ADASS is vibrant, interesting and at the cutting edge of our subject we need to take collective responsibility for shaping its future. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.04506v1.pdf"}
{"id": "1503.04518", "abstract": "  Gravitational collapse of a shell of charged dust surrounded by the phantom dark energy is probed by the minimal area surface, which is dual to probe the thermalization in the boundary quantum field by expectation values of Wilson loop in the framework of the AdS/CFT correspondence. We investigated mainly the effect of the phantom dark energy parameter and chemical potential on the thermalization. The result shows that the smaller the phantom dark energy parameter is, the easier the plasma thermalizes as the chemical potential is fixed, and the larger the chemical potential is, the harder the plasma thermalizes as the dark energy parameter is fixed. We get the fitting function of the thermalization curve and with it, the thermalization velocity and thermalization acceleration are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.04518v1.pdf"}
{"id": "1503.04649", "abstract": "  We study a recently proposed Einstein-Podolsky-Rosen steering inequality [arXiv- 1412.8178 (2014)]. Analogous to Clauser-Horne-Shimony-Holt (CHSH) inequality for Bell nonlocality, in the simplest scenario, i.e., 2 parties, 2 measurements per party and 2 outcomes per measurement, this newly proposed inequality has been proved to be necessary and sufficient for steering. In this article, using an equivalence between measurement incompatibility (non joint measurability) and steering, we find the optimal violation amount of this inequality in quantum theory. Interestingly, the optimal violation amount matches with optimal quantum violation of CHSH inequality, i.e., Cirel'son quantity. We further study the optimal violation of this inequality for different bipartite quantum states. To our surprise we find that optimal violation amount is different for different 2-qubit pure entangled states, which is not the case for all other existing steering inequalities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.04649v1.pdf"}
{"id": "1503.05098", "abstract": "  Within the last fifteen years, network theory has been successfully applied both to natural sciences and to socioeconomic disciplines. In particular, bipartite networks have been recognized to provide a particularly insightful representation of many systems, ranging from mutualistic networks in ecology to trade networks in economy, whence the need of a pattern detection-oriented analysis in order to identify statistically-significant structural properties. Such an analysis rests upon the definition of suitable null models, i.e. upon the choice of the portion of network structure to be preserved while randomizing everything else. However, quite surprisingly, little work has been done so far to define null models for real bipartite networks. The aim of the present work is to fill this gap, extending a recently-proposed method to randomize monopartite networks to bipartite networks. While the proposed formalism is perfectly general, we apply our method to the binary, undirected, bipartite representation of the World Trade Web, comparing the observed values of a number of structural quantities of interest with the expected ones, calculated via our randomization procedure. Interestingly, the behavior of the World Trade Web in this new representation is strongly different from the monopartite analogue, showing highly non-trivial patterns of self-organization. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.05098v2.pdf"}
{"id": "1503.06650", "abstract": "  This work considers the infinite-time discounted optimal control problem for continuous time input-affine polynomial dynamical systems subject to polynomial state and box input constraints. We propose a sequence of sum-of-squares (SOS) approximations of this problem obtained by first lifting the original problem into the space of measures with continuous densities and then restricting these densities to polynomials. These approximations are tightenings, rather than relaxations, of the original problem and provide a sequence of rational controllers with value functions associated to these controllers converging (under some technical assumptions) to the value function of the original problem. In addition, we describe a method to obtain polynomial approximations from above and from below to the value function of the extracted rational controllers, and a method to obtain approximations from below to the optimal value function of the original problem, thereby obtaining a sequence of asymptotically optimal rational controllers with explicit estimates of suboptimality. Numerical examples demonstrate the approach. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.06650v1.pdf"}
{"id": "1503.06975", "abstract": "  A brief outline of the Lorentz Integral Transform (LIT) method is given. The method is well established and allows to treat reactions into the many-body continuum with bound-state like techniques. The energy resolution that can be achieved is studied by means of a simple two-body reaction. From the discussion it will become clear that the LIT method is an approach with a controlled resolution and that there is no principle problem to even resolve narrow resonances in the many-body continuum. As an example the isoscalar monopole resonance of 4He is considered. The importance of the choice of a proper basis for the expansion of the LIT states is pointed out. Employing such a basis a width of 180(70) keV is found for the 4He isoscalar monopole resonance when using a simple central nucleon-nucleon potential model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.06975v2.pdf"}
{"id": "1503.07413", "abstract": "  The present paper is elaborated to discuss the energy condition bounds in a modified teleparallel gravity namely F(T,T_G), involving torsion invariant T and contribution from a term T_G, the teleparallel equivalent of the Gauss-Bonnet term. For this purpose, we consider flat FRW universe with matter contents as perfect fluid. We formulate the SEC, NEC, WEC and DEC in terms of some cosmic parameters including Hubble, deceleration, jerk and snap parameters. By taking two interesting models for F(T,T_G) and some recent limits of these cosmic parameters, we explore the constraints on the free parameters present in both assumed models. We also discuss these constraints graphically in terms of cosmic time by taking power law cosmology into account. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.07413v1.pdf"}
{"id": "1503.07918", "abstract": "  Among the direct search experiments for weakly interacting massive particle (WIMP) dark matter, the DAMA experiment observed an annual modulation signal interpreted as WIMP interactions with a significance of 9.2σ. Recently, Jonathan Davis claimed that the DAMA modulation may be interpreted on the basis of the neutron scattering events induced by the muons and neutrinos together. We tried to simulate the neutron backgrounds at the Gran Sasso and Yangyang laboratory with and without the polyethylene shielding to quantify the effects of the ambient neutrons on the direct detection experiments based on the crystals. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1503/1503.07918v1.pdf"}
{"id": "1504.00897", "abstract": "  A Fermi accelerator is a billiard with oscillating walls. A leaky accelerator interacts with an environment of an ideal gas at equilibrium by exchange of particles through a small hole on its boundary. Such interaction may heat the gas: we estimate the net energy flow through the hole under the assumption that the particles inside the billiard do not collide with each other and remain in the accelerator for sufficiently long time. The heat production is found to depend strongly on the type of the Fermi accelerator. An ergodic accelerator, i.e. one which has a single ergodic component, produces a weaker energy flow than a multi-component accelerator. Specifically, in the ergodic case the energy gain is independent of the hole size, whereas in the multi-component case the energy flow may be significantly increased by shrinking the hole size. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.00897v1.pdf"}
{"id": "1504.01735", "abstract": "  Accurate determinations of stellar mass functions and ages of stellar populations are crucial to much of astrophysics. We analyse the evolution of stellar mass functions of coeval main sequence stars including all relevant aspects of single- and binary-star evolution. We show that the slope of the upper part of the mass function in a stellar cluster can be quite different to the slope of the initial mass function. Wind mass loss from massive stars leads to an accumulation of stars which is visible as a peak at the high mass end of mass functions, thereby flattening the mass function slope. Mass accretion and mergers in close binary systems create a tail of rejuvenated binary products. These blue straggler stars extend the single star mass function by up to a factor of two in mass and can appear up to ten times younger than their parent stellar cluster. Cluster ages derived from their most massive stars that are close to the turn-off may thus be significantly biased. To overcome such difficulties, we propose the use of the binary tail of stellar mass functions as an unambiguous clock to derive the cluster age because the location of the onset of the binary tail identifies the cluster turn-off mass. It is indicated by a pronounced jump in the mass function of old stellar populations and by the wind mass loss peak in young stellar populations. We further characterise the binary induced blue straggler population in star clusters in terms of their frequency, binary fraction and apparent age. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.01735v1.pdf"}
{"id": "1504.06103", "abstract": "  In this paper, we propose a novel method for visual object tracking called HMMTxD. The method fuses observations from complementary out-of-the box trackers and a detector by utilizing a hidden Markov model whose latent states correspond to a binary vector expressing the failure of individual trackers. The Markov model is trained in an unsupervised way, relying on an online learned detector to provide a source of tracker-independent information for a modified Baum- Welch algorithm that updates the model w.r.t. the partially annotated data.   We show the effectiveness of the proposed method on combination of two and three tracking algorithms. The performance of HMMTxD is evaluated on two standard benchmarks (CVPR2013 and VOT) and on a rich collection of 77 publicly available sequences. The HMMTxD outperforms the state-of-the-art, often significantly, on all datasets in almost all criteria. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.06103v2.pdf"}
{"id": "1504.06118", "abstract": "  We present an analysis of stationary discrete shock profiles for a discontinuous Galerkin method approximating scalar nonlinear hyperbolic conservation laws with a convex flux. Using the Godunov method for the numerical flux, we characterize the steady state solutions for arbitrary approximation orders and show that they are oscillatory only in one mesh cell and are parametrized by the shock strength and its relative position in the cell. In the particular case of the inviscid Burgers equation, we derive analytical solutions of the numerical scheme and predict their oscillations up to fourth-order of accuracy. Moreover, a linear stability analysis shows that these profiles may become unstable at points where the Godunov flux is not differentiable. Theoretical and numerical investigations show that these results can be extended to other numerical fluxes. In particular, shock profiles are found to vanish exponentially fast from the shock position for some class of monotone numerical fluxes and the oscillatory and unstable characters of their solutions present strong similarities with that of the Godunov method. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.06118v1.pdf"}
{"id": "1504.07665", "abstract": "  Monte Carlo simulations of mono– and polydisperse two–dimensional crystals are reported. The particles in the studied system, interacting through hard–core repulsive Yukawa potential, form a solid phase of hexagonal lattice. The elastic properties of crystalline Yukawa systems are determined in the NpT ensemble with variable shape of the periodic box. Effects of the Debye screening length (κ^-1), contact value of the potential (ϵ), and the size polydispersity of particles on elastic properties of the system are studied. The simulations show that the polydispersity of particles strongly influences the elastic properties of the studied system, especially on the shear modulus. It is also found that the elastic moduli increase with density and their growth rate depends on the screening length. Shorter screening length leads to faster increase of elastic moduli with density and decrease of the Poisson's ratio. In contrast to its three-dimensional version, the studied system is non-auxetic, i.e. shows positive Poisson's ratio. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.07665v1.pdf"}
{"id": "1504.07822", "abstract": "  We analyse intensity variations, as measured by the Atmospheric Imaging Assembly (AIA) in the 171 Å passband, in two coronal loops embedded within a single coronal magnetic arcade. We detect oscillations in the fundamental mode with periods of roughly 2 minutes and decay times of 5 minutes. The oscillations were initiated by interaction of the arcade with a large wavefront issuing from a flare site. Further, the power spectra of the oscillations evince signatures consistent with oblique propagation to the field lines and for the existence of a 2-D waveguide instead of a 1-D one. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.07822v1.pdf"}
{"id": "1504.07908", "abstract": "  This paper considers a nonstationary multiserver queuing model with abandonment and balking for inbound call centers. We present a continuous time Markov chain (CTMC) model which captures the important characteristics of an inbound call center and obtain a numerical solution for its transient state probabilities using uniformization method with steady-state detection. Keywords: call center, transient, Markov processes, numerical methods, uniformization, abandonment, balking ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1504/1504.07908v1.pdf"}
{"id": "1505.00677", "abstract": "  In this paper we will present a quantization method for SPP (Surface Plasmon Polariton) based on Green's tensor method, which is applied usually for quantization of EM-field in various dielectric media. This method will be applied for a semi-infinite structure, which contains metal and dielectric regions with one interface. Moreover, by introducing the quantized SPP, we will investigate the SPP propagation in the attenuating and amplifying systems. We will also consider two modes of SPP, i.e., coherent and squeezed states, and finally compare the propagation of these modes in the amplifying media. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.00677v1.pdf"}
{"id": "1505.01226", "abstract": "  We experimentally demonstrate a simple method to measure the biphoton joint spectrum by mapping the spectral information onto the temporal domain using a dispersive medium. Various top-hat spectral filters are used to limit the spectral (and hence, temporal) extent of the broadband downconversion photons measured. The sharp edges of the spectral filters are utilized as spectral markers for dispersion characterization of the dispersive medium. This method allows dispersion characterization and joint spectral measurement to be completed simultaneously. The joint spectrum (which extends beyond 100 nm, centered about 1.5 micron) of the type-II downconverted photon pairs generated from a poled optical fiber is obtained with this method. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.01226v1.pdf"}
{"id": "1505.01554", "abstract": "  We present an approach to utilize large amounts of web data for learning CNNs. Specifically inspired by curriculum learning, we present a two-step approach for CNN training. First, we use easy images to train an initial visual representation. We then use this initial CNN and adapt it to harder, more realistic images by leveraging the structure of data and categories. We demonstrate that our two-stage CNN outperforms a fine-tuned CNN trained on ImageNet on Pascal VOC 2012. We also demonstrate the strength of webly supervised learning by localizing objects in web images and training a R-CNN style detector. It achieves the best performance on VOC 2007 where no VOC training data is used. Finally, we show our approach is quite robust to noise and performs comparably even when we use image search results from March 2013 (pre-CNN image search era). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.01554v2.pdf"}
{"id": "1505.01631", "abstract": "  In this paper we present a semi-automatic 2D-3D local registration pipeline capable of coloring 3D models obtained from 3D scanners by using uncalibrated images. The proposed pipeline exploits the Structure from Motion (SfM) technique in order to reconstruct a sparse representation of the 3D object and obtain the camera parameters from image feature matches. We then coarsely register the reconstructed 3D model to the scanned one through the Scale Iterative Closest Point (SICP) algorithm. SICP provides the global scale, rotation and translation parameters, using minimal manual user intervention. In the final processing stage, a local registration refinement algorithm optimizes the color projection of the aligned photos on the 3D object removing the blurring/ghosting artefacts introduced due to small inaccuracies during the registration. The proposed pipeline is capable of handling real world cases with a range of characteristics from objects with low level geometric features to complex ones. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.01631v1.pdf"}
{"id": "1505.02699", "abstract": "  We construct periodic approximations to the free energies of Ising models on fractal lattices of dimension smaller than two, in the case of zero external magnetic field, using a generalization of the combinatorial method of Feynman and Vodvickenko. Our procedure is applicable to any fractal obtained by the removal of sites of a periodic two dimensional lattice. As a first application, we compute estimates for the critical temperatures of many different Sierpinski carpets and we compare them to known Monte Carlo estimates. The results show that our method is capable of determining the critical temperature with, possibly, arbitrary accuracy and paves the way to determine T_c for any fractal of dimension below two. Critical exponents are more difficult to determine since the free energy of any periodic approximation still has a logarithmic singularity at the critical point implying α = 0. We also compute the correlation length as a function of the temperature and extract the relative critical exponent. We find ν=1 for all periodic approximation, as expected from universality. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.02699v2.pdf"}
{"id": "1505.02786", "abstract": "  Polarization of the > 400 keV hard tail of the microquasar Cygnus X-1 has been independently reported by INTEGRAL/IBIS, and INTEGRAL/SPI and interpreted as emission from a compact jet. These conclusions were, however, based on the accumulation of all INTEGRAL data regardless of the spectral state. We utilize additional INTEGRAL exposure accumulated until December 2012, and include the AMI/Ryle (15 GHz) radio data in our study. We separate the observations into hard, soft, and intermediate/transitional states and detect radio emission from a compact jet in hard and intermediate states, but not in the soft. The 10-400 keV INTEGRAL (JEM-X and IBIS) state resolved spectra are well modeled with thermal Comptonization and reflection components. We detect a hard tail in the 0.4-2 MeV range for the hard state only. We extract the state dependent polarigrams of Cyg X-1, which all are compatible to no or undetectable level of polarization except in 400-2000 keV range in the hard state where the polarization fraction is 75±32 ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.02786v1.pdf"}
{"id": "1505.03093", "abstract": "  In this work it is proposed a medical image segmentation pipeline for accurate bone segmentation from CT imaging. It is a two-step methodology, with a pre-segmentation step and a segmentation refinement step. First, the user performs a rough segmenting of the desired region of interest. Next, a fully automatic refinement step is applied to the pre-segmented data. The automatic segmentation refinement is composed by several sub-stpng, namely image deconvolution, image cropping and interpolation. The user-defined pre-segmentation is then refined over the deconvolved, cropped, and up-sampled version of the image. The algorithm is applied in the segmentation of CT images of a composite femur bone, reconstructed with different reconstruction protocols. Segmentation outcomes are validated against a gold standard model obtained with coordinate measuring machine Nikon Metris LK V20 with a digital line scanner LC60-D that guarantees an accuracy of 28 μ m. High sub-pixel accuracy models were obtained for all tested Datasets. The algorithm is able to produce high quality segmentation of the composite femur regardless of the surface meshing strategy used. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.03093v1.pdf"}
{"id": "1506.02673", "abstract": "  Free nucleons propagating in water are known to produce gamma rays, which form a background to the searches for diffuse supernova neutrinos and sterile neutrinos carried out with Cherenkov detectors. As a consequence, the process of nucleon knockout induced by neutral-current quasielastic interactions of atmospheric (anti)neutrinos with oxygen needs to be under control at the quantitative level in the background simulations of the ongoing and future experiments. In this paper, we provide a quantitative assessment of the uncertainty associated with the theoretical description of the nuclear cross sections, estimating it from the discrepancies between the predictions of different models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1506/1506.02673v1.pdf"}
{"id": "1506.02859", "abstract": "  The hysteresis behaviors of anisotropic S-1 Heisenberg model have been studied within the effective field theory with two spin cluster. After giving the phase diagrams, the effect of the crystal field and anisotropy in the exchange interaction on the hysteresis loops have been determined. One important finding is double hysteresis loop behavior of the system in the low temperature and negative crystal field region, which disappears with the decreasing anisotropy in the exchange interaction. This behavior was carefully investigated and physical explanation has also been given. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1506/1506.02859v1.pdf"}
{"id": "1506.03959", "abstract": "  The continuum-fitting method is one of the two most advanced methods of determining the black hole spin in accreting X-ray binary systems. There are, however, still some unresolved issues with the underlying disk models. One of them manifests as an apparent decrease in spin for increasing source luminosity. Here, we perform a few simple tests to establish whether outflows from the disk close to the inner radius can address this problem. We employ four different parametric models to describe the wind and compare these to the apparent decrease in spin with luminosity measured in the sources LMC X-3 and GRS 1915+105. Wind models in which parameters do not explicitly depend on the accretion rate cannot reproduce the spin measurements. Models with mass accretion rate dependent outflows, however, have spectra that emulate the observed ones. The assumption of a wind thus effectively removes the artifact of spin decrease. This solution is not unique; the same conclusion can be obtained with a truncated inner disk model. To distinguish among valid models, high resolution X-ray data and a realistic description of the Comptonization in the wind will be needed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1506/1506.03959v2.pdf"}
{"id": "1506.05010", "abstract": "  We use determinant quantum Monte Carlo to study the single particle properties of quasiparticles and phonons in a variant of the two-dimensional Holstein model that includes an additional non-linear electron-phonon (e-ph) interaction. We find that a small positive non-linear interaction reduces the effective coupling between the electrons and the lattice, suppresses charge-density wave (CDW) correlations, and hardens the effective phonon frequency. Conversely, a small negative non-linear interaction can enhance the e-ph coupling resulting in heavier quasiparticles, an increased tendency towards a CDW phase at all fillings, and a softened phonon frequency. An effective linear model with a renormalized interaction strength and phonon frequency can qualitatively capture this physics; however, the quantitative effects of the non-linearity on both the electronic and phononic degrees of freedom cannot be captured by such a model. These results are significant for typical non-linear coupling strengths found in real materials, indicating that non-linearity can have a significant influence on the physics of many e-ph coupled systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1506/1506.05010v1.pdf"}
{"id": "1506.07472", "abstract": "  Evolutionary game theory is a powerful framework for studying evolution in populations of interacting individuals. A common assumption in evolutionary game theory is that interactions are symmetric, which means that the players are distinguished by only their strategies. In nature, however, the microscopic interactions between players are nearly always asymmetric due to environmental effects, differing baseline characteristics, and other possible sources of heterogeneity. To model these phenomena, we introduce into evolutionary game theory two broad classes of asymmetric interactions: ecological and genotypic. Ecological asymmetry results from variation in the environments of the players, while genotypic asymmetry is a consequence of the players having differing baseline genotypes. We develop a theory of these forms of asymmetry for games in structured populations and use the classical social dilemmas, the Prisoner's Dilemma and the Snowdrift Game, for illustrations. Interestingly, asymmetric games reveal essential differences between models of genetic evolution based on reproduction and models of cultural evolution based on imitation that are not apparent in symmetric games. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1506/1506.07472v1.pdf"}
{"id": "1506.08059", "abstract": "  Previous approaches of emergent thermalization for condensed matter based on typical wavefunctions are extended to generate an intrinsically quantum theory of gases. Gases are fundamentally quantum objects at all temperatures, by virtue of rapid delocalization of their constituents. When there is a sufficiently broad spread in the energy of eigenstates, a well-defined temperature is shown to arise by photon production when the samples are optically thick. This produces a highly accurate approximation to the Planck distribution so that thermalization arises from the initial data as a consequence of purely quantum and unitary dynamics. These results are used as a foil for some common hydrodynamic theory of ultracold gases. It is suggested here that strong history dependence typically remains in these gases and so limits the validity of thermodynamics in their description. These problems are even more profound in the extension of hydrodynamics to such gases when they are optically thin, even when their internal energy is not low. We investigate rotation of elliptically trapped gases and consistency problems with deriving a local hydrodynamic approach. The presence of vorticity that is \"hidden\" from order parameter approaches is discussed along with some buoyancy intrinsically associated with vorticity that gives essential quantum corrections to gases in the regimes where standard perturbation approaches to the Boltzmann equations are known to fail to converge. These results suggest that studying of trapped gases in the far from ultracold regions may yield interesting results not described by classical hydrodynamics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1506/1506.08059v1.pdf"}
{"id": "1507.00050", "abstract": "  Due to elastic anisotropy, two-dimensional patterning of substrates can promote weak azimuthal alignment of adjacent nematic liquid crystals. Here, we consider how such alignment can be achieved using a periodic square lattice of circular or elliptical motifs. In particular, we examine ways in which the lattice and motif can compete to favor differing orientations. Using Monte Carlo simulation and continuum elasticity we find, for circular motifs, an orientational transition depending on the coverage fraction. If the circles are generalised to ellipses, arbitrary control of the effective alignment direction and anchoring energy becomes achievable by appropriate tuning of the ellipse motif relative to the periodic lattice patterning. This has possible applications in both monostable and bi-stable liquid crystal device contexts. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.00050v1.pdf"}
{"id": "1507.01458", "abstract": "  We present a graph-theoretic model of consumer choice, where final decisions are shown to be influenced by information and knowledge, in the form of individual awareness, discriminating ability, and perception of market structure. Building upon the distance-based Hotelling's differentiation idea, we describe the behavioral experience of several prototypes of consumers, who walk a hypothetical cognitive path in an attempt to maximize their satisfaction. Our simulations show that even consumers endowed with a small amount of information and knowledge may reach a very high level of utility. On the other hand, complete ignorance negatively affects the whole consumption process. In addition, rather unexpectedly, a random walk on the graph reveals to be a winning strategy, below a minimal threshold of information and knowledge. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.01458v1.pdf"}
{"id": "1507.02098", "abstract": "  All-dielectric \"magnetic light\" nanophotonics based on high refractive index nanoparticles allows controlling magnetic component of light at nanoscale without having high dissipative losses. The artificial magnetic optical response of such nanoparticles originates from circular displacement currents excited inside those structures and strongly depends on geometry and dispersion of optical materials. Here a new approach for increasing magnetic response via resonant bianisotropy effect is proposed and analyzed. The key mechanism of enhancement is based on electric-magnetic interaction between two electrically and magnetically resonant nanoparticles of all-dielectric dimer nanoantenna. It was shown that proper geometrical arrangement of the dimer in respect to the incident illumination direction allows flexible control over all vectorial components of magnetic polarizability, tailoring the later in the dynamical range of 100 ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.02098v1.pdf"}
{"id": "1507.02196", "abstract": "  This paper discusses the relevance and potential impact of both RFID and reverse engineering of RFID technology, followed by a discussion of common protocols and internals of RFID technology. The focus of the paper is on providing an overview of the different approaches to reverse engineering RFID technology and possible countermeasures that could limit the potential of such reverse engineering attempts. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.02196v1.pdf"}
{"id": "1507.04444", "abstract": "  We study a system of interacting spinless fermions in one dimension which, in the absence of interactions, reduces to the Kitaev chain [A. Yu Kitaev, Phys.-Usp. 44, 131 (2001)]. In the non-interacting case, a signal of topological order appears as zero-energy modes localized near the edges. We show that the exact ground states can be obtained analytically even in the presence of nearest-neighbor repulsive interactions when the on-site (chemical) potential is tuned to a particular function of the other parameters. As with the non-interacting case, the obtained ground states are two-fold degenerate and differ in fermionic parity. We prove the uniqueness of the obtained ground states and show that they can be continuously deformed to the ground states of the non-interacting Kitaev chain without gap closing. We also demonstrate explicitly that there exists a set of operators each of which maps one of the ground states to the other with opposite fermionic parity. These operators can be thought of as an interacting generalization of Majorana edge zero modes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.04444v2.pdf"}
{"id": "1507.04529", "abstract": "  The non-Markovian stochastic dynamics involving Levy flights and a potential in the form of a harmonic and non-linear oscillator is discussed. The subordination technique is applied and the memory effects, which are nonhomogeneous, are taken into account by a position-dependent subordinator. In the non-linear case, the asymptotic stationary states are found. The relaxation pattern to the stationary state is derived for the quadratic potential: the density decays like a linear combination of the Mittag-Leffler functions. It is demonstrated that in the latter case the density distribution satisfies a fractional Fokker-Planck equation. The densities for the non-linear oscillator reveal a complex picture, qualitatively dependent on the potential strength, and the relaxation pattern is exponential at large time. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.04529v1.pdf"}
{"id": "1507.06203", "abstract": "  Massive MIMO is a new technique for wireless communications that claims to offer very high system throughput and energy efficiency in multi-user scenarios. The cost is to add a very large number of antennas at the base station. Theoretical research has probed these benefits, but very few measurements have showed the potential of Massive MIMO in practice. We investigate the properties of measured Massive MIMO channels in a large indoor venue. We describe a measurement campaign using 3 arrays having different shape and aperture, with 64 antennas and 8 users with 2 antennas each. We focus on the impact of the array aperture which is the main limiting factor in the degrees of freedom available in the multiple antenna channel. We find that performance is improved as the aperture increases, with an impact mostly visible in crowded scenarios where the users are closely spaced. We also test MIMO capability within a same user device with user proximity effect. We see a good channel resolvability with confirmation of the strong effect of the user hand grip. At last, we highlight that propagation conditions where line-of-sight is dominant can be favorable. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.06203v1.pdf"}
{"id": "1507.08095", "abstract": "  We study approximation error bounds of isogeometric function spaces on a specific type of singularly parameterized domains. In this context an isogeometric function is the composition of a piecewise rational function with the inverse of a piecewise rational geometry parameterization. We consider domains where one edge of the parameter domain is mapped onto one point in physical space. To be more precise, in our configuration the singular patch is derived from a reparameterization of a regular triangular patch. On such a domain one can define an isogeometric function space fulfilling certain regularity criteria that guarantee optimal convergence. The main contribution of this paper is to prove approximation error bounds for the previously defined class of isogeometric discretizations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.08095v1.pdf"}
{"id": "1507.08122", "abstract": "  We present an exact rewriting of the Mie coefficients describing the scattering of light by a spherical core-shell particle which enables their interpretation in terms of an hybridization of the two surface modes arising, respectively, at the core-shell and the shell-medium interface. For this particular case we thus obtain from the Mie theory–analytically for all multipole orders and hence for arbitrarily sized particles–the hybridization scenario, which so far has been employed primarily for small particles in the electrostatic approximation. To demonstrate the strength of the rewriting approach we also extract the hybridization scenario for a stratified sphere directly from the expansion coefficients for the electromagnetic fields. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.08122v2.pdf"}
{"id": "1507.08215", "abstract": "  We present a model in which planetesimal disks are built from the combination of planetesimal formation and accretion of radially drifting pebbles onto existing planetesimals. In this model, the rate of accretion of pebbles onto planetesimals quickly outpaces the rate of direct planetesimal formation in the inner disk. This allows for the formation of a high mass inner disk without the need for enhanced planetesimal formation or a massive protoplanetary disk. Our proposed mechanism for planetesimal disk growth does not require any special conditions to operate. Consequently, we expect that high mass planetesimal disks form naturally in nearly all systems. The extent of this growth is controlled by the total mass in pebbles that drifts through the inner disk. Anything that reduces the rate or duration of pebble delivery will correspondingly reduce the final mass of the planetesimal disk. Therefore, we expect that low mass stars (with less massive protoplanetary disks), low metallicity stars and stars with giant planets should all grow less massive planetesimal disks. The evolution of planetesimal disks into planetary systems remains a mystery. However, we argue that late stage planet formation models should begin with a massive disk. This reinforces the idea that massive and compact planetary systems could form in situ but does not exclude the possibility that significant migration occurs post-planet formation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.08215v1.pdf"}
{"id": "1507.08228", "abstract": "  When gently placing a droplet onto a vertically vibrated bath, a drop can bounce without coalescing. Upon increasing the forcing acceleration, the droplet is propelled by the wave it generates and becomes a walker with a well defined speed. We investigate the confinement of a walker in different rectangular cavities, used as waveguides for the Faraday waves emitted by successive droplet bounces. By studying the walker velocities, we discover that 1d confinement is optimal for narrow channels of width of D ≃ 1.5 λ_F. We also propose an analogy with waveguide models based on the observation of the Faraday instability within the channels. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.08228v2.pdf"}
{"id": "1508.01300", "abstract": "  We study the time needed for deterministic leader election in the LOCAL model, where in every round a node can exchange any messages with its neighbors and perform any local computations. The topology of the network is unknown and nodes are unlabeled, but ports at each node have arbitrary fixed labelings which, together with the topology of the network, can create asymmetries to be exploited in leader election. We consider two versions of the leader election problem: strong LE in which exactly one leader has to be elected, if this is possible, while all nodes must terminate declaring that leader election is impossible otherwise, and weak LE, which differs from strong LE in that no requirement on the behavior of nodes is imposed, if leader election is impossible. We show that the time of leader election depends on three parameters of the network: its diameter D, its size n, and its level of symmetry λ, which, when leader election is feasible, is the smallest depth at which some node has a unique view of the network. It also depends on the knowledge by the nodes, or lack of it, of parameters D and n. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.01300v1.pdf"}
{"id": "1508.01652", "abstract": "  The temporal evolution of the entanglement between two qubits evolving by random interactions is studied analytically and numerically. Two different types of randomness are investigated. Firstly we analyze an ensemble of systems with randomly chosen but time-independent interaction Hamiltonians. Secondly we consider the case of a temporally fluctuating Hamiltonian, where the unitary evolution can be understood as a random walk on the SU (4) group manifold. As a by-product we compute the metric tensor and its inverse as well as the Laplace-Beltrami for SU (4). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.01652v2.pdf"}
{"id": "1508.02317", "abstract": "  We study the stability of cosmic string wakes against the disruption by the dominant Gaussian fluctuations which are present in cosmological models. We find that for a string tension given by G μ = 10^-7 wakes remain locally stable until a redshift of z = 6, and for a value of G μ = 10^-14 they are stable beyond a redshift of z = 20. We study a global stability criterion which shows that wakes created by strings at times after t_eq are identifiable up to the present time, independent of the value of G μ. Taking into account our criteria it is possible to develop strategies to search for the distinctive position space signals in cosmological maps which are induced by wakes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.02317v3.pdf"}
{"id": "1508.02878", "abstract": "  For each d>0, we find all the smallest fullerenes for which the least distance between two pentagons is d. We also show that for each d there is an h_d such that fullerenes with pentagons at least distance d apart and any number of hexagons greater than or equal to h_d exist.   We also determine the number of fullerenes where the minimum distance between any two pentagons is at least d, for 1 ≤ d ≤ 5, up to 400 vertices. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.02878v1.pdf"}
{"id": "1508.02975", "abstract": "  Alternating sign matrices and totally symmetric self-complementary plane partitions are equinumerous sets of objects for which no explicit bijection is known. In this paper, we identify a subset of totally symmetric self-complementary plane partitions corresponding to permutations by giving a statistic-preserving bijection to permutation matrices, which are a subset of alternating sign matrices. We use this bijection to define a new partial order on permutations, and prove this new poset contains both the Tamari lattice and the Catalan distributive lattice as subposets. We also study a new partial order on totally symmetric self-complementary plane partitions arising from this perspective and show that this is a distributive lattice related to Bruhat order when restricted to permutations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.02975v2.pdf"}
{"id": "1508.03994", "abstract": "  To date, quantum mechanics has proven to be our most successful theoretical model. However, it is still surrounded by a \"mysterious halo\" that can be summarized in a simple but challenging question: Why quantum phenomena are not understood under the same logic as classical ones? Although this is an open question (probably without an answer), from a pragmatist's point of view there is still room enough to further explore the quantum world, marveling ourselves with new physical insights. We just need to look back in the historical evolution of the quantum theory and thoroughly reconsider three key issues: (1) how this has developed since its early stages at a conceptual level, (2) what kind of experiments can be performed at present in a laboratory, and (3) what nonstandard conceptual models are available to extract some extra information. This contribution is aimed at providing some answers (and, perhaps, also raising some issues) to these questions through one of such models, namely Bohmian mechanics, a hydrodynamic formulation of the quantum theory, which is currently trying to open new pathways of understanding. Specifically, the Chapter constitutes a brief and personal overview on the historic and contextual evolution of this quantum formulation, its physical meaning and interest (leaving aside metaphysical issues), and how it may help to overcome some preconceived paradoxical aspects of the quantum theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.03994v1.pdf"}
{"id": "1508.04069", "abstract": "  We investigate an ideal gas in a time–dependent external trapping potential. We use the Boltzmann equation with the relaxation time ansatz to explore the time–dependent energy of an adiabatically isolated system. In particular we are interested on the dissipation during a potential change along a given protocol with finite velocity. The role of the relaxation less evolution as a limiting case is studied: starting from an equilibrium distribution and for small times the energy of the gas with relaxation is always smaller than that of the relaxation–less. This means that relaxation processes show an ambivalent behavior: on the one hand entropy production, but on the other hand reduction of dissipation by driving back the system into equilibrium. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.04069v1.pdf"}
{"id": "1508.04606", "abstract": "  This paper studies synchronization of dynamical networks with event-based communication. Firstly, two estimators are introduced into each node, one to estimate its own state, and the other to estimate the average state of its neighbours. Then, with these two estimators, a distributed event-triggering rule (ETR) with a dwell time is designed such that the network achieves synchronization asymptotically with no Zeno behaviours. The designed ETR only depends on the information that each node can obtain, and thus can be implemented in a decentralized way. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.04606v3.pdf"}
{"id": "1508.05654", "abstract": "  The large nucleon-nucleon scattering length, and the isospin approximate symmetry, are low energy properties of quantum chromodynamics (QCD). These entail correlations in the binding energies of light nuclei, e.g., the A=3 iso-multiplet, and Tjon's correlation between the binding energy of three and four body nuclei. Using a new representation of these, we establish that they translate into a correlation between different short-range contributions to three body forces in chiral effective field theory of low-energy nuclear physics. We demonstrate that these correlations should be taken into account in order to avoid fine-tuning in the calibration of three body forces. We relate this to the role of correlations in uncertainty quantification of non-renormalizable effective field theories of the nuclear regime. In addition, we show that correlations can be useful in assessing the importance of forces induced by renormalization group (RG) transformations. We give numerical evidence that such RG transformations can be represented effectively by adding a constant to the pure three nucleon contact low energy constant c_E. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.05654v1.pdf"}
{"id": "1508.06548", "abstract": "  Magnetic domain structure and spin-dependent reflectivity measurements on cobalt thin films intercalated at the graphene / Ir(111) interface are investigated using spin-polarised low-energy electron microscopy. We find that graphene-covered cobalt films have surprising magnetic properties. Vectorial imaging of magnetic domains reveals an unusually gradual thickness-dependent spin reorientation transition, in which magnetisation rotates from out-of-the-film plane to the in-plane direction by less than 10^∘ per cobalt monolayer. During this transition, cobalt films have a meandering spin texture, characterised by a complex, three-dimensional, wavy magnetisation pattern. In addition, spectroscopy measurements indicate that the electronic band structure of the unoccupied states is essentially spin-independent already a few electron-Volts above the vacuum level. These properties strikingly differ from those of pristine cobalt films and could open new prospects in surface magnetism. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.06548v1.pdf"}
{"id": "1508.06840", "abstract": "  This study introduces a modified quadratic Lorenz attractor. The properties of this new chaotic system are analysed and discussed in detail, by determining the equilibria points, the eigenvalues of the Jacobian, and the Lyapunov exponents. The numerical simulations, the time series analysis, and the projections to the xy-plane, xz-plane, and yz-plane are conducted to highlight the chaotic behaviour. The multiplicative form of the new system is also presented and the simulations are conducted using multiplicative Runge-Kutta methods. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.06840v1.pdf"}
{"id": "1508.06990", "abstract": "  With the use of long-term numerical simulations, we study the evolution and orbital behavior of cometary nuclei in cold Kuiper belt-like debris disks under the gravitational influence of dwarf planets (DPs); we carry out these simulations with and without the presence of a Neptune-like giant planet. This exploratory study shows that in the absence of a giant planet, 10 DPs are enough to induce strong radial and vertical heating on the orbits of belt particles. On the other hand, the presence of a giant planet close to the debris disk, acts as a stability agent reducing the radial and vertical heating. With enough DPs, even in the presence of a Neptune-like giant planet some radial heating remains; this heating grows steadily, re-filling resonances otherwise empty of cometary nuclei. Specifically for the solar system, this secular process seems to be able to provide material that, through resonant chaotic diffusion, increase the rate of new comets spiraling into the inner planetary system, but only if more than the ∼10 known DP sized objects exist in the trans-Neptunian region. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1508/1508.06990v1.pdf"}
{"id": "1509.00905", "abstract": "  The matched interface and boundary (MIB) method has a proven ability for delivering the second order accuracy in handling elliptic interface problems with arbitrarily complex interface geometries. However, its collocation formulation requires relatively high solution regularity. Finite volume method (FVM) has its merit in dealing with conservation law problems and its integral formulation works well with relatively low solution regularity. We propose an MIB-FVM to take the advantages of both MIB and FVM for solving elliptic interface problems. We construct the proposed method on Cartesian meshes with vertex-centered control volumes. A large number of numerical experiments are designed to validate the present method in both two dimensional (2D) and three dimensional (3D) domains. It is found that the proposed MIB-FVM achieves the second order convergence for elliptic interface problems with complex interface geometries in both L_∞ and L_2 norms. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.00905v1.pdf"}
{"id": "1509.01381", "abstract": "  Understanding the conditions ensuring the persistence of a population is an issue of primary importance in population biology. The first theoretical approach to the problem dates back to the 50's with the KiSS (after Kierstead, Slobodkin and Skellam) model, namely a continuous reaction-diffusion equation for a population growing on a patch of finite size L surrounded by a deadly environment with infinite mortality – i.e. an oasis in a desert. The main outcome of the model is that only patches above a critical size allow for population persistence. Here, we introduce an individual-based analogue of the KiSS model to investigate the effects of discreteness and demographic stochasticity. In particular, we study the average time to extinction both above and below the critical patch size of the continuous model and investigate the quasi-stationary distribution of the number of individuals for patch sizes above the critical threshold. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.01381v1.pdf"}
{"id": "1509.02161", "abstract": "  This work presents exchange potentials for specific orbitals calculated by inverting Hartree-Fock wavefunctions. This was achieved by using a Depurated Inversion Method. The basic idea of the method relies upon the substitution of Hartree-Fock orbitals and eigenvalues into the Kohn-Sham equation. Through inversion, the corresponding effective potentials were obtained. Further treatment of the inverted potential should be carried on. The depuration is a careful optimization which eliminates the poles and also ensures the fullfilment of the appropriate boundary conditions. The procedure developed here is not restricted to the ground state or to a nodeless orbital and is applicable to all kinds of atoms. As an example, exchange potentials for noble gases and term-dependent orbitals of the lower configuration of Nitrogen are calculated. The method allows to reproduce the input energies and wavefunctions with a remarkable degree of accuracy. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.02161v6.pdf"}
{"id": "1509.03304", "abstract": "  The ekpyrotic phase (a slow contraction cosmic phase before the current expansion phase) manages to solve the main problems of the standard cosmology by means of a scalar field interpreted as a cosmic fluid in the Friedmann equation. Moreover, this phase generates a nearly scale-invariant spectrum of perturbations in agreement with the latest data. Then, the ekpyrotic mechanism is a serious possibility to the inflationary model. In this work, by using the approach of deforming metrics at linear level, we point out that it is impossible to generate a black hole with spherical symmetry supported by an isotropic fluid in this cosmological scenario. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.03304v2.pdf"}
{"id": "1509.04034", "abstract": "  Radio interferometers suffer from the problem of missing information in their data, due to the gaps between the antennas. This results in artifacts, such as bright rings around sources, in the images obtained. Multiple deconvolution algorithms have been proposed to solve this problem and produce cleaner radio images. However, these algorithms are unable to correctly estimate uncertainties in derived scientific parameters or to always include the effects of instrumental errors. We propose an alternative technique called Bayesian Inference for Radio Observations (BIRO) which uses a Bayesian statistical framework to determine the scientific parameters and instrumental errors simultaneously directly from the raw data, without making an image. We use a simple simulation of Westerbork Synthesis Radio Telescope data including pointing errors and beam parameters as instrumental effects, to demonstrate the use of BIRO. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.04034v1.pdf"}
{"id": "1509.04454", "abstract": "  Muon beams are customarily obtained via K/π decays produced in proton interaction on target. In this paper we investigate the possibility to produce low emittance muon beams from electron-positron collisions at centre-of-mass energy just above the μ^+μ^- production threshold with maximal beam energy asymmetry, corresponding to a positron beam of about 45 GeV interacting on electrons on target. We present the main features of this scheme with an outline of the possible applications. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.04454v1.pdf"}
{"id": "1509.05131", "abstract": "  We study the geodesic motion of massless test particles in the background of a magnetic charged black hole spacetime in four dimensions in dilaton-Maxwell gravity. The behaviour of effective potential in view of the different values of black hole parameters is analysed in the equatorial plane. The possible orbits for null geodesics are also discussed in detail in view of the different values of the impact parameter. We have also calculated the frequency shift of photons in this spacetime. The results obtained are then compared with those for the electrically charged stringy black hole spacetime and the Schwarzschild black hole spacetime. It is observed that there exists no stable circular orbit outside the event horizon for massless test particles. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.05131v1.pdf"}
{"id": "1509.05689", "abstract": "  We report the discovery of a low-mass companion to HR3549, an A0V star surrounded by a debris disk with a warm excess detected by WISE at 22 μm (10σ significance). We imaged HR3549 B in the L-band with NAOS-CONICA, the adaptive optics infrared camera of the Very Large Telescope, in January 2013 and confirmed its common proper motion in January 2015. The companion is at a projected separation of ≃ 80 AU and position angle of ≃ 157^∘, so it is orbiting well beyond the warm disk inner edge of r > 10 AU. Our age estimate for this system corresponds to a companion mass in the range 15-80 M_J, spanning the brown dwarf regime, and so HR3549 B is another recent addition to the growing list of brown dwarf desert objects with extreme mass ratios. The simultaneous presence of a warm disk and a brown dwarf around HR3549 provides interesting empirical constraints on models of the formation of substellar companions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.05689v1.pdf"}
{"id": "1509.06314", "abstract": "  This paper proposes a novel scheme which can efficiently reduce the energy consumption of Optical Line Terminals (OLTs) in Time Division Multiplexing (TDM) Passive Optical Networks (PONs) such as EPON and GPON. Currently, OLTs consume a significant amount of energy in PON, which is one of the major FTTx technologies. To be environmentally friendly, it is desirable to reduce energy consumption of OLT as much as possible; such requirement becomes even more urgent as OLT keeps increasing its provisioning data rate, and higher data rate provisioning usually implies higher energy consumption. In this paper, we propose a novel energy-efficient OLT structure which guarantees services of end users with the smallest number of power-on OLT line cards. More specifically, we adapt the number of power-on OLT line cards to the real-time incoming traffic. Also, in order to avoid service disruption resulted by powering off OLT line cards, proper optical switches are equipped in OLT to dynamically configure the communications between OLT line cards and ONUs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.06314v1.pdf"}
{"id": "1509.07014", "abstract": "  In this paper we consider three dimensional BTZ black holes with three models of nonlinear electrodynamics as source. Calculating heat capacity, we study the stability and phase transitions of these black holes. We show that Maxwell, logarithmic and exponential theories yield only type one phase transition which is related to the root(s) of heat capacity. Whereas for correction form of nonlinear electrodynamics, heat capacity contains two roots and one divergence point. Next, we use geometrical approach for studying classical thermodynamical behavior of the system. We show that Weinhold and Ruppeiner metrics fail to provide fruitful results and the consequences of the Quevedo approach are not completely matched to the heat capacity results. Then, we employ a new metric for solving this problem. We show that this approach is successful and all divergencies of its Ricci scalar and phase transition points coincide. We also show that there is no phase transition for uncharged BTZ black holes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.07014v1.pdf"}
{"id": "1509.08321", "abstract": "  We present an analysis of the polymorphic energy ordering and properties of the rock salt and zincblende structures of manganese oxide using fixed node diffusion Monte Carlo (DMC). Manganese oxide is a correlated, antiferromagnetic material that has proven to be challenging to model from first principles across a variety of approaches. Unlike conventional density functional theory and some hybrid functionals, fixed node diffusion Monte Carlo finds the rock salt structure to be more stable than the zincblende structure, and thus recovers the correct energy ordering. Analysis of the site-resolved charge fluctuations of the wave functions according to DMC and other electronic structure descriptions give insights into elements that are missing in other theories. While the calculated band gaps within DMC are in agreement with predictions that the zincblende polymorph has a lower band gap, the gaps themselves overestimate reported experimental values. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.08321v2.pdf"}
{"id": "1509.09022", "abstract": "  We put forward a hydrodynamic theory of nematic liquid crystals that includes both anisotropic elasticity and dynamic relaxation. Liquid remodeling is encompassed through a continuous update of the shear-stress free configuration. The low-frequency limit of the dynamical theory reproduces the classical Ericksen-Leslie theory, but it predicts two independent identities between the six Leslie viscosity coefficients. One replicates Parodi's relation, while the other-which involves five Leslie viscosities in a nonlinear way-is new. We discuss its significance, and we test its validity against evidence from physical experiments, independent theoretical predictions, and molecular-dynamics simulations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.09022v2.pdf"}
{"id": "1510.02871", "abstract": "  Mixture models provide a flexible representation of heterogeneity in a finite number of latent classes. From the Bayesian point of view, Markov Chain Monte Carlo methods provide a way to draw inferences from these models. In particular, when the number of subpopulations is considered unknown, more sophisticated methods are required to perform Bayesian analysis. The Reversible Jump Markov Chain Monte Carlo is an alternative method for computing the posterior distribution by simulation in this case. Some problems associated with the Bayesian analysis of these class of models are frequent, such as the so-called \"label-switching\" problem. However, as the level of heterogeneity in the population increases, these problems are expected to become less frequent and the model's performance to improve. Thus, the aim of this work is to evaluate the normal mixture model fit using simulated data under different settings of heterogeneity and prior information about the mixture proportions. A simulation study is also presented to evaluate the model's performance considering the number of components known and estimating it. Finally, the model is applied to a censored real dataset containing antibody levels of Cytomegalovirus in individuals. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.02871v2.pdf"}
{"id": "1510.03154", "abstract": "  The evolution equation for inhomogeneous and anisotropic temperature fluctuation inside a medium is derived within the ambit of Boltzmann Transport Equation (BTE) for a hot gas of massless particles. Also, specializing to a situation created after heavy-ion collision (HIC), we analyze the Fourier space variation of temperature fluctuation of the medium using its temperature profile. The effect of viscosity on the variation of fluctuations in the latter case is investigated and possible implications for early universe cosmology, and its connection with HICs are also explored. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.03154v2.pdf"}
{"id": "1510.04488", "abstract": "  In this paper, we study the stability of light traffic achieved by a scheduling algorithm which is suitable for heterogeneous traffic networks. Since analyzing a scheduling algorithm is intractable using the conventional mathematical tool, our goal is to minimize the largest queue-overflow probability achieved by the algorithm. In the large deviation setting, this problem is equivalent to maximizing the asymptotic decay rate of the largest queue-overflow probability. We first derive an upper bound on the decay rate of the queue overflow probability as the queue overflow threshold approaches infinity. Then, we study several structural properties of the minimum-cost-path to overflow of the queue with the largest length, which is basically equivalent to the decay rate of the largest queue-overflow probability. Given these properties, we prove that the queue with the largest length follows a sample path with linear increment. For certain parameter value, the scheduling algorithm is asymptotically optimal in reducing the largest queue length. Through numerical results, we have shown the large deviation properties of the queue length typically used in practice while varying one parameter of the algorithm. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.04488v3.pdf"}
{"id": "1510.06408", "abstract": "  We analyse the process of energy exchanges generated by the elastic collisions between a point-particle, confined to a two-dimensional cell with convex boundaries, and a `piston', i.e. a line-segment, which moves back and forth along a one-dimensional interval partially intersecting the cell. This model can be considered as the elementary building block of a spatially extended high-dimensional billiard modeling heat transport in a class of hybrid materials exhibiting the kinetics of gases and spatial structure of solids. Using heuristic arguments and numerical analysis, we argue that, in a regime of rare interactions, the billiard process converges to a Markov jump process for the energy exchanges and obtain the expression of its generator. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.06408v2.pdf"}
{"id": "1510.07009", "abstract": "  We report on a large-scale characterization of river discharges by employing the network framework of the horizontal visibility graph. By mapping daily time series from 141 different stations of 53 Brazilian rivers into complex networks, we present an useful approach for investigating the dynamics of river flows. We verified that the degree distributions of these networks were well described by exponential functions, where the characteristic exponents are almost always larger than the value obtained for random time series. The faster-than-random decay of the degree distributions is an another evidence that the fluctuation dynamics underlying the river discharges has a long-range correlated nature. We further investigated the evolution of the river discharges by tracking the values of the characteristic exponents (of the degree distribution) and the global clustering coefficients of the networks over the years. We show that the river discharges in several stations have evolved to become more or less correlated (and displaying more or less complex internal network structures) over the years, a behavior that could be related to changes in the climate system and other man-made phenomena. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.07009v2.pdf"}
{"id": "1510.07065", "abstract": "  We present a unitary multichannel model for K̅N scattering in the resonance region that fulfills unitarity. It has the correct analytical properties for the amplitudes once they are extended to the complex-s plane and the partial waves have the right threshold behavior. To determine the parameters of the model, we have fitted single-energy partial waves up to J=7/2 and up to 2.15 GeV of energy in the center-of-mass reference frame obtaining the poles of the Λ^* and Σ^* resonances, which are compared to previous analyses. We provide the most comprehensive picture of the S=-1 hyperon spectrum to date. Important differences are found between the available analyses making the gathering of further experimental information on K̅N scattering mandatory to make progress in the assessment of the hyperon spectrum. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.07065v2.pdf"}
{"id": "1510.07239", "abstract": "  The Haldane model of the Chern insulator is considered on the Lieb and honeycomb lattices. We provide a detailed analysis of the model's ground-state phase diagram and demonstrate a scenario of the topological phase transitions in the system with a single-particle spectrum that includes flat and dispersion bands, that is realized on the Lieb lattice. We find that the Chern number of the flat band is non-zero, depending on the parameters of the model. We define the topological metal state as an intermediate state between topological insulator and trivial metal. The phase transition between topological insulator and topological metal states is accompanied by continuous changing of the Chern number, a jump of the surface charge or spin current defines the point of the topological metal-trivial metal phase transition. The results have been illustrated with numerical calculations of the model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.07239v1.pdf"}
{"id": "1510.07315", "abstract": "  In this paper we present a single-microphone speech enhancement algorithm. A hybrid approach is proposed merging the generative mixture of Gaussians (MoG) model and the discriminative neural network (NN). The proposed algorithm is executed in two phases, the training phase, which does not recur, and the test phase. First, the noise-free speech power spectral density (PSD) is modeled as a MoG, representing the phoneme based diversity in the speech signal. An NN is then trained with phoneme labeled database for phoneme classification with mel-frequency cepstral coefficients (MFCC) as the input features. Given the phoneme classification results, a speech presence probability (SPP) is obtained using both the generative and discriminative models. Soft spectral subtraction is then executed while simultaneously, the noise estimation is updated. The discriminative NN maintain the continuity of the speech and the generative phoneme-based MoG preserves the speech spectral structure. Extensive experimental study using real speech and noise signals is provided. We also compare the proposed algorithm with alternative speech enhancement algorithms. We show that we obtain a significant improvement over previous methods in terms of both speech quality measures and speech recognition results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.07315v1.pdf"}
{"id": "1510.07869", "abstract": "  The possibility that some meteoroids in the size range 1 - 20 meters are rubble piles i.e. assembles of boulders of various sizes held together only by small van der Waals forces, is investigated. Such meteoroids are expected to start disrupting into individual pieces during the atmospheric entry at very low dynamic pressures of   25 Pa, even before the onset of ablation. The heterogeneous bodies as Almahata Sitta (asteroid 2008 TC3) and Benesov are primary candidates for rubble piles. Nevertheless, by analyzing the deceleration, wake, and light curve of the Benesov bolide, we found that the meteoroid disruption started only at a height of 70 km under dynamic pressure of 50 kPa. No evidence for a very early fragmentation was found also for the Chelyabinsk event. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.07869v1.pdf"}
{"id": "1511.01850", "abstract": "  We consider two special types of double pendula, with the motion of masses restricted to various surfaces. In order to get quick insight into the dynamics of the considered systems the Poincaré cross sections as well as bifurcation diagrams have been used. The numerical computations show that both models are chaotic which suggest that they are not integrable. We give an analytic proof of this fact checking the properties of the differential Galois group of the system's variational equations along a particular non-equilibrium solution. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.01850v1.pdf"}
{"id": "1511.06469", "abstract": "  Quantum error correction protects the quantum state against noise and decoherence in quantum communication and quantum computation, which enables one to perform fault-torrent quantum information processing. We experimentally demonstrate a quantum error correction scheme with a five-wave-packet code against a single stochastic error, the original theoretical model of which is firstly proposed by S. L. Braunstein and T. A. Walker. Five submodes of a continuous variable cluster entangled state of light are used for five encoding channels. Especially, in our encoding scheme the information of the input state is only distributed on three of the five channels and thus any error appearing in the remained two channels never affects the output state, i.e. the output quantum state is immune from the error in the two channels. The stochastic error on a single channel is corrected for both vacuum and squeezed input states and the achieved fidelities of the output states are beyond the corresponding classical limit. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.06469v1.pdf"}
{"id": "1511.06796", "abstract": "  We show that the electron mobility in ideal, free-standing two-dimensional `buckled' crystals with broken horizontal mirror (σ_ h) symmetry and Dirac-like dispersion (such as silicene and germanene) is dramatically affected by scattering with the acoustic flexural modes (ZA phonons). This is caused both by the broken σ_ h symmetry and by the diverging number of long-wavelength ZA phonons, consistent with the Mermin-Wagner theorem. Non-σ_ h-symmetric, `gapped' 2D crystals (such as semiconducting transition-metal dichalcogenides with a tetragonal crystal structure) are affected less severely by the broken σ_ h symmetry, but equally seriously by the large population of the acoustic flexural modes. We speculate that reasonable long-wavelength cutoffs needed to stabilize the structure (finite sample size, grain size, wrinkles, defects) or the anharmonic coupling between flexural and in-plane acoustic modes (shown to be effective in mirror-symmetric crystals, like free-standing graphene) may not be sufficient to raise the electron mobility to satisfactory values. Additional effects (such as clamping and phonon-stiffening by the substrate and/or gate insulator) may be required. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.06796v2.pdf"}
{"id": "1512.04136", "abstract": "  In this paper, we propose a method to describe the many-body problem of electrons in honeycomb materials via the introduction of random fields which are coupled to the electrons and have a Gaussian distribution. From a one-body approach to the problem, after integrating exactly the contribution of the random fields, one builds a non-hermitian and dissipative effective Hamiltonian with two-body interactions. Our approach introduces besides the usual average over the electron field a second average over the random fields. The interplay of two averages enables the definition of various types of Green's functions which allow the investigation of fluctuation-dissipation characteristics of the interactions that are a manifestation of the many-body problem. In the current work we study only the dissipative term, through the perturbative analysis of the dynamics associated the effective Hamiltonian generated by two different kinds of couplings. For the cases analysed, the eigenstates of the effective Hamiltonian are complex and, therefore, some of the states have a finite life time. Moreover, we also investigate, in the mean field approximation, the most general parity conserving coupling to the random fields and compute the width of charge carriers Γ as a function of the Fermi energy E_F. The theoretical prediction for Γ (E_F) is compared to the available experimental data for graphene. The good agreement between Γ_theo and Γ_exp suggests that description of the many-body problem associated to the electrons in honeycomb materials can indeed be done via the introduction of random fields. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.04136v1.pdf"}
{"id": "1512.04363", "abstract": "  We investigate the dynamics of solar activity using a nonlinear one-dimensional dynamo model and a phenomenological equation for the evolution of Wolf numbers. This system of equations is solved numerically. We take into account the algebraic and dynamic nonlinearities of the alpha effect. The dynamic nonlinearity is related to the evolution of a small-scale magnetic helicity, and it leads to a complicated behavior of solar activity. The evolution equation for the Wolf number is based on a mechanism of formation of magnetic spots as a result of the negative effective magnetic pressure instability (NEMPI). This phenomenon was predicted 25 years ago and has been investigated intensively in recent years through direct numerical simulations and mean-field simulations. The evolution equation for the Wolf number includes the production and decay of sunspots. Comparison between the results of numerical simulations and observational data of Wolf numbers shows a 70 ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.04363v4.pdf"}
{"id": "1512.04664", "abstract": "  Small 3He-rich solar energetic particle (SEP) events with their anomalous abundances, markedly different from solar system, provide evidence for a unique acceleration mechanism that operates routinely near solar active regions. Although the events are sometimes accompanied by coronal mass ejections (CMEs) it is believed that mass and isotopic fractionation is produced directly in the flare sites on the Sun. We report on a large-scale extreme ultraviolet (EUV) coronal wave observed in association with 3He-rich SEP events. In the two examples discussed, the observed waves were triggered by minor flares and appeared concurrently with EUV jets and type III radio bursts but without CMEs. The energy spectra from one event are consistent with so-called class-1 (characterized by power laws) while the other with class-2 (characterized by rounded 3He and Fe spectra) 3He-rich SEP events, suggesting different acceleration mechanisms in the two. The observation of EUV waves suggests that large-scale disturbances, in addition to more commonly associated jets, may be responsible for the production of 3He-rich SEP events. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.04664v1.pdf"}
{"id": "1512.04861", "abstract": "  Spin-driven nematic order that has been proposed for iron-based superconductors is generated by pronounced fluctuations of a striped density wave state. On the other hand it is a well known fact that nematic order parameter couples bilinearly to the strain, which supresses the fluctuations of the nematic order parameter itself and lowers the upper critical dimension, yielding mean-field behaviour of the nematic degrees of freedom for d>2. This is consistent with the measured Currie-Weiss behaviour of the nematic susceptibility. Here we reconcile this apparent contradiction between pronounced magnetic fluctuations and mean-field behaviour of the nematic degrees of freedom. We show, by developing a φ^4 theory for the nematic degrees of freedom, that the coupling to elastic strain does not suppress the fluctuations that cause the nematic order in the first place (magnetic fluctuations), yet it does transform the Ising-nematic transition into a mean-field transition. In addition, we demonstrate that the mean field behavior occurs in the entire temperature regime where a softening of the shear modulus is observed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.04861v1.pdf"}
{"id": "1512.05445", "abstract": "  Physicists experimentalists use a large number of observations of a phenomenon, where are the unknown equations that describe it, in order to play the dynamics and obtain information on their future behavior. In this article we study the possibility of reproducing the dynamics of the phenomenon using only a measurement scale. The Whitney immersion theorem ideas are presented and generalization of Sauer for fractal sets to rebuild the asymptotic behaviour of the phenomena and to investigate, chaotic behavior evidence in the reproduced dynamics. The applications are made in the financial market which are only known stock prices. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.05445v1.pdf"}
{"id": "1512.07888", "abstract": "  We analyse the trapping of eigenspinors of the charge conjugation operator with dual helicity (Elko), in thin and thick string-like models with codimension-2. Elko spinor fields describe mass dimension one fermions in four dimensions (and, correspondingly, mass dimension two fermions in six dimensions), that represent natural dark matter prime candidates. This dark spinor has many applications, from particle physics to cosmology. On the other hand, six-dimensional brane-world models have, among other prominent features, the spontaneous confinement of free spin 1 fields and a mechanism that explains the mass hierarchy of fundamental fermions. In this paper, we use scalar couplings in order to confine the zero mode of Elko in six dimensions. Moreover, we use the Elko dark spinor features to propose an exotic coupling in order to remove the complex-valued terms in the massive Kaluza-Klein modes. Hence, we show that six dimensional models can resolve the main issues of Elko fields confinement presented in five dimensions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.07888v2.pdf"}
{"id": "1512.09361", "abstract": "  A device that achieves controllable rotation of the state of polarization by rotating the orientation of the eigenmodes of a waveguide by 45^∘ is introduced and analyzed. The device can be implemented using lossless materials on a nanoscale and helps circumvent the inherent polarization dependence of photonic devices realized within the silicon on insulator platform. We propose and evaluate two novel polarization rotator-based schemes to achieve polarization engineering functions: (1) A multi-purpose device, with dimensions on the order of a few wavelengths which can function as a polarization splitter or an arbitrary linear polarization state generator. (2) An energy efficient optical modulator that utilizes eigenmode rotation and epsilon near zero (ENZ) effects to achieve high extinction ratio, polarization insensitive amplitude modulation without the need to sweep the device geometry to match the TE and TM mode attributes. By using indium tin oxide (ITO) as an example for a tunable material, the proposed modulator provides polarization insensitive operation and can be realized with a modulation bandwidth of 112 GHz, a length of 1800 nm an energy per bit of 7.5 fJ and an optical bandwidth of 210 nm. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.09361v1.pdf"}
{"id": "1601.04040", "abstract": "  The Hawking radiation is considered as a quantum tunneling process, which can be studied in the framework of the Hamilton-Jacobi method. In this study, we present the wave equation for a mass generating massive and charged scalar particle (boson). In sequel, we analyze the quantum tunneling of these bosons from a generic 4-dimensional spherically symmetric black hole. We apply the Hamilton-Jacobi formalism to derive the radial integral solution for the classically forbidden action which leads to the tunneling probability. To support our arguments, we take the dyonic Reissner-Nordström black hole as a test background. Comparing the tunneling probability obtained with the Boltzmann formula, we succeed to read the standard Hawking temperature of the dyonic Reissner-Nordström black hole. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.04040v2.pdf"}
{"id": "1601.04291", "abstract": "  For successful electroweak baryogenesis to take place through the sphaleron process the universe needs to undergo a strong first order cosmological phase transition. While it does not occur in the Standard Model it becomes possible in the presence of extra scalars in BSM. One of these scalars can well be responsible for the recently observed diphoton excess in the CMS and ATLAS experiments in LHC. We study the Electroweak phase transition in a myriad of scalar models in this context. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.04291v1.pdf"}
{"id": "1601.04419", "abstract": "  We discuss the forward and inverse problems between the potential V(x) measured in a heart chamber and its sources represented by a dipole density d(y) located on the heart wall. We show that the mapping from d(y) to V(x) is a compact integral operator. Its inverse is unbounded which makes the inverse problem ill-posed in the mathematical sense. We investigate methods to solve the inverse problem approximately in view of the mapping of complicated cardiac arrhythmias. We point out an analogy between phase mapping and 2-dimensional hydrodynamics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.04419v1.pdf"}
{"id": "1601.06483", "abstract": "  The quantum and classical behaviors of two-dimensional (2D) alternative quantum walk (AQW) in the presence of decoherence have been discussed in detail. For any kinds of decoherence, the analytic expressions for the moments of position distribution of AQW have been obtained. Taking the broken line noise and coin-decoherence as examples of decoherence, we find that when the decoherence only emerges in one direction, the anisotropic position distribution pattern appears, and not all the motions of quantum walkers exhibit the transition from quantum to classical behaviors. The correlations between the walkers and the coin in 2D AQW have been discussed. The anisotropic correlations between walkers and coin have been revealed in the presence of decoherence. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.06483v1.pdf"}
{"id": "1601.06703", "abstract": "  Rippling patterns of myxobacteria appear in starving colonies before they aggregate to form fruiting bodies. These periodic traveling cell density waves arise from the coordination of individual cell reversals, resulting from an internal clock regulating them, and from contact signaling during bacterial collisions. Here we revisit a mathematical model of rippling in myxobacteria due to Igoshin et al. [Proc. Natl. Acad. Sci. USA 98, 14913 (2001) and Phys. Rev. E 70, 041911 (2004)]. Bacteria in this model are phase oscillators with an extra internal phase through which they are coupled to a mean-field of oppositely moving bacteria. Previously, patterns for this model were obtained only by numerical methods and it was not possible to find their wavenumber analytically. We derive an evolution equation for the reversal point density that selects the pattern wavenumber in the weak signaling limit, show the validity of the selection rule by solving numerically the model equations and describe other stable patterns in the strong signaling limit. The nonlocal mean-field coupling tends to decohere and confine patterns. Under appropriate circumstances, it can annihilate the patterns leaving a constant density state via a nonequilibrium phase transition reminiscent of destruction of synchronization in the Kuramoto model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.06703v1.pdf"}
{"id": "1601.07192", "abstract": "  In this paper, a network of hypertension-related genes is constructed by analyzing the correlations of gene expression data among the Dahl salt-sensitive rat and two consomic rat strains. The numerical calculations show that this sparse and assortative network has small-world and scale-free properties. Further, 16 key hub genes (Col4a1, Lcn2, Cdk4, etc.) are determined by introducing an integrated centrality and have been confirmed by biological/medical research to play important roles in hypertension. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.07192v1.pdf"}
{"id": "1601.07781", "abstract": "  The anomalous magnetic moment of the muon is an important observable that tests radiative corrections of all three observed local gauge forces: electromagnetic, weak and strong interactions. High precision measurements reveal some discrepancy with the most accurate theoretical evaluations of the anomalous magnetic moment. We show in this note that the UV finite theory cannot resolve this discrepancy. We believe that more reliable estimate of the nonperturbative hadronic contribution and the new measurements can resolve the problem. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.07781v1.pdf"}
{"id": "1602.00089", "abstract": "  The Casimir effect is a physical manifestation of zero point energy of quantum vacuum. In a relativistic quantum field theory, Poincaré symmetry of the theory seems, at first sight, to imply that non-zero vacuum energy is inconsistent with translational invariance of the vacuum. In the setting of two uniform boundary plates at rest, quantum fields outside the plates have (1+2)-dimensional Poincaré symmtry. Taking a massless scalar field as an example, we have examined the consistency between the Poincaré symmetry and the existence of the vacuum enegy. We note that, in quantum theory, symmetries are represented projectively in general and show that the Casimir energy is connected to central charges appearing in the algebra of generators in the projective representations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.00089v2.pdf"}
{"id": "1602.01259", "abstract": "  A set of idealized experiments are performed to analyze the competing effects of declining atmospheric CO2 concentrations, the opening of an ocean gateway, and varying orbital parameters. These forcing mechanisms, which influence the global mean climate state, may have played a role for triggering climate transitions of the past (for example during the Eocene-Oligocene climate transition and the build-up of the Antarctic Ice Sheet). Sensitivity simulations with a coupled atmosphere-ocean general circulation model are conducted to test these three forcings and their roles for the global climate. The simulations are carried out under idealized conditions to focus on the essentials. The combination of all three forcings triggers a climate transition which resembles the onset of the Antarctic glaciation. In particular, the temperatures in the southern high latitudes decrease and snow accumulates constantly. Moreover, the relative importance of each possible forcing is explored. All three of the mechanisms (atmospheric CO2 decrease, opening of the ocean gateways, and changing orbital parameters) cool the climate of the southern polar continent. The change induced by the orbital parameters depends strongly on the magnitude of the change in obliquity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.01259v1.pdf"}
{"id": "1602.01680", "abstract": "  Numerical prediction of multiscale heat transfer is a challenging problem due to the wide range of time and length scales involved. In this work a discrete unified gas kinetic scheme (DUGKS) is developed for heat transfer in materials with different acoustic thickness based on the phonon Boltzmann equation. With discrete phonon direction, the Boltzmann equation is discretized with a second-order finite-volume formulation, in which the time-step is fully determined by the Courant-Friedrichs-Lewy (CFL) condition. The scheme has the asymptotic preserving (AP) properties for both diffusive and ballistic regimes, and can present accurate solutions in the whole transition regime as well. The DUGKS is a self-adaptive multiscale method for the capturing of local transport process. Numerical tests for both heat transfers with different Knudsen numbers are presented to validate the current method. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.01680v1.pdf"}
{"id": "1602.04568", "abstract": "  This paper defines the (first-order) conflict resolution calculus: an extension of the resolution calculus inspired by techniques used in modern SAT-solvers. The resolution inference is restricted to (first-order) unit-propagation and the calculus is extended with a mechanism for assuming decision literals and a new inference rule for clause learning, which is a first-order generalization of the propositional conflict-driven clause learning (CDCL) procedure. The calculus is sound (because it can be simulated by natural deduction) and refutationally complete (because it can simulate resolution), and these facts are proven in detail here. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.04568v1.pdf"}
{"id": "1602.05358", "abstract": "  Chaos synchronization may arise in networks of nonlinear units with delayed couplings. We study complete and sublattice synchronization generated by resonance of two large time delays with a specific ratio. As it is known for single delay networks, the number of synchronized sublattices is determined by the Greatest Common Divisor (GCD) of the network loops lengths. We demonstrate analytically the GCD condition in networks of iterated Bernouilli maps with multiple delay times and complement our analytic results by numerical phase diagrams, providing parameter regions showing complete and sublattice synchronization by resonance for Tent and Bernouilli maps. We compare networks with the same GCD with single and multiple delays, and we investigate the sensitivity of the correlation to a detuning between the delays in a network of coupled Stuart-Landau oscillators. Moreover, the GCD condition also allows to detect time delay resonances leading to high correlations in non-synchronizable networks. Specifically, GCD-induced resonances are observed both in a chaotic asymmetric network and in doubly connected rings of delay-coupled noisy linear oscillators. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.05358v1.pdf"}
{"id": "1602.06021", "abstract": "  3 transmembrane and 4 transmembrane helices models are suggested for the human vitamin K epoxide reductase (VKOR). In this study, we investigate the stability of the human 3 transmembrane/4 transmembrane VKOR models employing a coarse-grained normal mode analysis and molecular dynamics simulation. Based on the analysis of the mobility of each transmembrane domain, we suggest that the 3 transmembrane human VKOR model is more stable than the 4 transmembrane human VKOR model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.06021v1.pdf"}
{"id": "1602.06928", "abstract": "  A combined nonequilibrium Green functions-Ehrenfest dynamics approach is developed that allows for a time-dependent study of the energy loss of a charged particle penetrating a strongly correlated system at zero and finite temperature. Numerical results are presented for finite inhomogeneous two-dimensional Fermi-Hubbard models, where the many-electron dynamics in the target are treated fully quantum mechanically and the motion of the projectile is treated classically. The simulations are based on the solution of the two-time Dyson (Keldysh-Kadanoff-Baym) equations using the second-order Born, third-order and T-matrix approximations of the self-energy. As application, we consider protons and helium nuclei with a kinetic energy between 1 and 500 keV/u passing through planar fragments of the two-dimensional honeycomb lattice and, in particular, examine the influence of electron-electron correlations on the energy exchange between projectile and electron system. We investigate the time dependence of the projectile's kinetic energy (stopping power), the electron density, the double occupancy and the photoemission spectrum. Finally, we show that, for a suitable choice of the Hubbard model parameters, the results for the stopping power are in fair agreement with ab-initio simulations for particle irradiation of single-layer graphene. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.06928v2.pdf"}
{"id": "1602.08466", "abstract": "  We consider the problem of transmission energy op- timization via range assignment for Low Power Nodes (LPNs) in Long Term Evolution (LTE) Heterogenous Networks (HetNets). The optimization is subject to the load coupling model, where the cells interfere with one another. Each cell provides data service for its users so as to maintain a target Quality-of-Service (QoS). We prove that, irrespective the presence of maximum power limit or its value, operating at full load is optimal. We perform energy minimization by optimizing the association between User Equipments (UEs) and cells via selecting cell- specific offsets on LPNs. Moreover, the optimization problem is proved to be NP-hard. We propose a tabu search algorithm for offset optimization (TSO). For each offset, TSO computes the optimal power solution such that all cells operate at full load. Numerical results demonstrate the significant performance improvement of TSO on optimizing the sum transmission energy, compared to the conventional solution where uniform offset is used for all LPNs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.08466v2.pdf"}
{"id": "1602.08921", "abstract": "  We examine current fluctuations in tunnel junctions driven by a superposition of a constant and a sinusoidal voltage source. In standard setups the external voltage is applied to the tunneling element via an impedance providing an electromagnetic environment of the junction. The modes of this environment are excited by the time-dependent voltage and are the source of Johnson-Nyquist noise. We determine the autocorrelation function of the current flowing in the leads of the junction in the weak tunneling limit up to terms of second order in the tunneling Hamiltonian. The driven modes of the electromagnetic environment are treated exactly by means of a unitary transformation introduced recently. Particular emphasis is placed on the spectral function of the current fluctuations. The spectrum is found to comprise three contributions: a term arising from the Johnson-Nyquist noise of the environmental impedance, a part due to the shot noise of the tunneling element and a third contribution which comes from the cross-correlation between fluctuations caused by the electromagnetic environment and fluctuations of the tunneling current. All three parts of the spectral function occur already for devices under dc bias. The spectral function of ac driven tunneling elements can be determined from the result for a dc bias by means of a photo-assisted tunneling relation of the Tien-Gordon type. Specific results are given for an Ohmic environment and for a junction driven through a resonator. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.08921v2.pdf"}
{"id": "1603.00985", "abstract": "  We report on a new concept of cloaking objects in diffusive light regime using the paradigm of the scattering cancellation and mantle cloaking techniques. We show numerically that an object can be made completely invisible to diffusive photon density waves, by tailoring the diffusivity constant of the spherical shell enclosing the object. This means that photons' flow outside the object and the cloak made of these spherical shells behaves as if the object were not present. Diffusive light invisibility may open new vistas in hiding hot spots in infrared thermography or tissue imaging. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.00985v1.pdf"}
{"id": "1603.01869", "abstract": "  In this paper, we investigate the impact of phase noise on the secrecy performance of downlink massive MIMO systems in the presence of a passive multiple-antenna eavesdropper. Thereby, for the base station (BS) and the legitimate users, the effect of multiplicative phase noise is taken into account, whereas the eavesdropper is assumed to employ ideal hardware. We derive a lower bound for the ergodic secrecy rate of a given user when matched filter data precoding and artificial noise transmission are employed at the BS. Based on the derived analytical expression, we investigate the impact of the various system parameters on the secrecy rate. Our analytical and simulation results reveal that distributively deployed local oscillators (LOs) can achieve a better performance than one common LO for all BS antennas as long as a sufficient amount of power is assigned for data transmission. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.01869v1.pdf"}
{"id": "1603.02868", "abstract": "  Radio telescope front ends must have simultaneously low noise and sufficiently-high linearity to accommodate interfering signals. Typically these are opposing design goals. For modern radio telescopes operating in the HF (3-30 MHz) and VHF-low (30-88 MHz) bands, the problem is more nuanced in that front end noise temperature may be a relatively small component of the system temperature, and increased linearity may be required due to the particular interference problems associated with this spectrum. In this paper we present an analysis of the sensitivity-linearity trade off at these frequencies, applicable to existing commercially-available monolithic microwave integrated circuit (MMIC) amplifiers in single-ended, differential, and parallelized configurations. This analysis and associated findings should be useful in the design and upgrade of front ends for low frequency radio telescopes. The analysis is demonstrated explicitly for one of the better-performing amplifiers encountered in this study, the Mini-Circuits PGA-103, and is confirmed by hardware measurements. We also present a design based on the Mini-Circuits HELA-10 amplifier, which is better-suited for applications where linearity is a primary concern. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.02868v1.pdf"}
{"id": "1603.03539", "abstract": "  We investigate the relative importance of two galactic outflow suppression mechanisms : a) Cosmological infall of the intergalactic gas onto the galaxy, and b) the existence of a hot circumgalactic medium (CGM). Considering only radial motion, the infall reduces the speed of outflowing gas and even halts the outflow, depending on the mass and redshift of the galaxy. For star forming galaxies there exists an upper mass limit beyond which outflows are suppressed by the gravitational field of the galaxy. We find that infall can reduce this upper mass limit approximately by a factor of two (independent of the redshift). Massive galaxies (≳ 10^12 M_⊙) host large reservoir of hot, diffuse CGM around the central part of the galaxy. The CGM acts as a barrier between the infalling and outflowing gas and provides an additional source of outflow suppression. We find that at low redshifts (z≲3.5), the CGM is more effective than the infall in suppressing the outflows. Together, these two processes give a mass range in which galaxies are unable to have effective outflows. We also discuss the impact of outflow suppression on the enrichment history of the galaxy and its environment. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.03539v1.pdf"}
{"id": "1603.05569", "abstract": "  The numerical simulation of turbulence in stars has led to a rich set of possibilities regarding stellar pulsations, asteroseismology, thermonuclear yields, and formation of neutron stars and black holes. The breaking of symmetry by turbulent flow grows in amplitude as collapse is approached, which insures that the conditions at the onset of collapse are not spherical. This lack of spherical symmetry has important implications for the mechanism of explosion and ejected nucleosynthesis products. Numerical resolution of several different types of three–dimensional (3D) stellar simulations are compared; it is suggested that core collapse simulations may be under-resolved.   New physical effects which appear in 3D are summarized.   Connections between simulations of progenitor explosion and observations of supernova remnants (SNR) are discussed.   Present treatment of boundaries, for mixing regions during He–burning, requires revision. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.05569v1.pdf"}
{"id": "1603.06892", "abstract": "  Tackling the low-temperature fate of supercooled liquids is challenging due to the immense timescales involved, which prevent equilibration and lead to the operational glass transition. Relating glassy behaviour to an underlying, thermodynamic phase transition is a long-standing open question in condensed matter physics. Like experiments, computer simulations are limited by the small time window over which a liquid can be equilibrated. Here we address the challenge of low temperature equilibration using trajectory sampling in a system undergoing a nonequilibrium phase transition. This transition occurs in trajectory space between the normal supercooled liquid and a glassy state rich in low-energy geometric motifs. Our results indicate that this transition might become accessible in equilibrium configurational space at a temperature close to the so-called Kauzmann temperature, and provide a possible route to unify dynamical and thermodynamical theories of the glass transition. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.06892v2.pdf"}
{"id": "1603.07157", "abstract": "  Natural and man-made networks often possess locally tree-like sub-structures. Taking such tree networks as our starting point, we show how the addition of links changes the synchronization properties of the network. We focus on two different methods of link addition. The first method adds single links that create cycles of a well-defined length. Following a topological approach we introduce cycles of varying length and analyze how this feature, as well as the position in the network, alters the synchronous behaviour. We show that in particular short cycles can lead to a maximum change of the Laplacian's eigenvalue spectrum, dictating the synchronization properties of such networks. The second method connects a certain proportion of the initially unconnected nodes. We simulate dynamical systems on these network topologies, with the nodes' local dynamics being either a discrete or continuous. Here our main result is that a certain amount of additional links, with the relative position in the network being crucial, can be beneficial to ensure stable synchronization. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.07157v2.pdf"}
{"id": "1603.09104", "abstract": "  The KdV equation is a model equation for waves at the surface of an inviscid incompressible fluid, and it is well known that the equation describes the evolution of unidirectional waves of small amplitude and long wavelength fairly accurately if the waves fall into the Boussinesq regime.   The KdV equation allows a balance of nonlinear steepening effects and dispersive spreading which leads to the formation of steady wave profiles in the form of solitary waves and cnoidal waves. While these wave profiles are solutions of the KdV equation for any amplitude, it is shown here that there for both the solitary and the cnoidal waves, there are critical amplitudes for which the horizontal component of the particle velocity matches the phase velocity of the wave. Solitary or cnoidal solutions of the KdV equation which surpass these amplitudes feature incipient wave breaking as the particle velocity exceeds the phase velocity near the crest of the wave, and the model breaks down due to violation of the kinematic surface boundary condition.   The condition for breaking can be conveniently formulated as a convective breaking criterion based on the local Froude number at the wave crest. This breaking criterion can also be applied to time-dependent situations, and one case of interest is the development of an undular bore created by an influx at a lateral boundary. It is shown that this boundary forcing leads to wave breaking in the leading wave behind the bore if a certain threshold is surpassed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.09104v1.pdf"}
{"id": "1604.00005", "abstract": "  Infrared emission from intergalactic dust might compromise the ability of future experiments to detect subtle spectral distortions in the Cosmic Microwave Background (CMB) from the early Universe. We provide the first estimate of foreground contamination of the CMB signal due to diffuse dust emission in the intergalactic medium. We use models of the extragalactic background light to calculate the intensity of intergalactic dust emission and find that emission by intergalactic dust at redshifts z<0.5 exceeds the sensitivity of the planned Primordial Inflation Explorer (PIXIE) to CMB spectral distortions by 1-3 orders of magnitude. We place an upper limit of 0.23", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.00005v1.pdf"}
{"id": "1604.00213", "abstract": "  In this paper we propose a very special relativity (VSR)-inspired generalization of the Maxwell-Chern-Simons (MCS) electrodynamics. This proposal is based upon the construction of a proper study of the SIM(1)–VSR gauge-symmetry. It is shown that the VSR nonlocal effects present a significant and health departure from the usual MCS theory. The classical dynamics is analysed in full detail, by studying the solution for the electric field and static energy for this configuration. Afterwards, the interaction energy between opposite charges are derived and we show that the VSR effects play an important part in obtaining a (novel) finite expression for the static potential. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.00213v1.pdf"}
{"id": "1604.01532", "abstract": "  We investigate theoretically the spectral and dynamical effects of the short-range exchange interaction between a single manganese (Mn) atom hosted by cylindrical CdTe quantum dots and its light-hole excitons or biexcitons. Our approach is based on the Kohn-Luttinger KP theory and configuration interaction method, the dynamics of the system in the presence of intraband relaxation being derived from the von Neumann-Lindblad equation. The complex structure of the light-hole exciton absorption spectrum reveals the exchange-induced exciton mixing and depends strongly on the Mn position. In particular, if the Mn atom is closer to the edges of the cylinder the bright and dark light-hole excitons are mixed by the hole-Mn exchange alone. Consequently, their populations exhibit exchange-induced Rabi oscillations which can be viewed as optical signatures of light-hole spin reversal. Similar results are obtained for mixed biexcitons, in this case the exchange-induced Rabi oscillations being damped by the intraband hole relaxation processes. The effect of light-hole heavy-hole mixing is also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.01532v1.pdf"}
{"id": "1604.02581", "abstract": "  In an optical color-magnitude diagram sub-subgiants (SSGs) lie red of the main sequence and fainter than the base of the red giant branch in a region not easily populated by standard stellar-evolution pathways. In this paper, we present multi-epoch radial velocities for five SSG candidates in the old and metal-rich open cluster NGC 6791 (8 Gyr, [Fe/H] = +0.30). From these data we are able to make three-dimensional kinematic membership determinations and confirm four SSG candidates to be likely cluster members. We also identify three member SSGs as short-period binary systems and present their orbital solutions. These are the first SSGs with known three-dimensional kinematic membership, binary status, and orbital parameters since the two SSGs in M67 studied by Mathieu et al. 2003. We also remark on the other properties of these stars including photometric variability, Hα emission, and X-ray luminosity. The membership confirmation of these SSGs in NGC 6791 strengthens the case that SSGs are a new class of nonstandard stellar evolution products, and that a physical mechanism must be found that explains the evolutionary paths of these stars. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.02581v1.pdf"}
{"id": "1604.02825", "abstract": "  Technology is moving towards space division multiplexing in optical fiber to keep up the trend in rate increase over time and to avoid an imminent capacity crunch. Thus, it is of paramount interest to estimate the potential gains of this approach. As more spatial channels are being packed into a single fiber, the increased crosstalk necessitates the use of MIMO to guarantee reliable operation. In this paper, we exploit the analogy between an optical fiber and a model from mesoscopic physics - a chaotic cavity - to obtain a novel channel model for the optical fiber. The model captures both random distributed crosstalk and modedependent loss, which are described within the framework of scattering theory. Using tools from replica theory and random matrix theory, we derive the capacity of the fiber optical MIMO channel model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.02825v1.pdf"}
{"id": "1604.03845", "abstract": "  We show that the operational definition of non-classicality of a quantum state depends on the motion of the observer. We use the relativistic Unruh-DeWitt detector model to witness nonclassicality of the probed field state. It turns out that the witness based on the properties of the P-representation of the quantum state depends on the trajectory of the detector. Inertial and noninertial motion of the device have qualitatively different impact on the performance of the witness. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.03845v2.pdf"}
{"id": "1604.03867", "abstract": "  In this chapter a quantum communication protocol with use of repeaters is presented. The protocol is constructed for qudits i.e. the generalized quantum information units. One-dit teleportation is based on the generalized Pauli-Z (phase-flip) gate's correction. This approach avoids using Pauli-X and Hadamard gates unlike in other known protocols based on quantum repeaters which were constructed for qubits and qudits. It is also important to mention that the repeaters based on teleportation protocol, described in this chapter, allow a measurement in the standard base (what simplifies the measurement process) and the use of teleportation causes only Pauli-Z operational errors. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.03867v1.pdf"}
{"id": "1604.05260", "abstract": "  The paper aims to extend major equations in the electromagnetic and gravitational theories from the flat space into the complex octonion curved space. Maxwell applied simultaneously the quaternion analysis and vector terminology to describe the electromagnetic theory. It inspires subsequent scholars to study the electromagnetic and gravitational theories with the complex quaternions/octonions. Furthermore Einstein was the first to depict the gravitational theory by means of tensor analysis and curved four-space-time. Nowadays some scholars investigate the electromagnetic and gravitational properties making use of the complex quaternion/octonion curved space. From the orthogonality of two complex quaternions, it is possible to define the covariant derivative of the complex quaternion curved space, describing the gravitational properties in the complex quaternion curved space. Further it is possible to define the covariant derivative of the complex octonion curved space by means of the orthogonality of two complex octonions, depicting simultaneously the electromagnetic and gravitational properties in the complex octonion curved space. The result reveals that the connection coefficient and curvature of the complex octonion curved space will exert an influence on the field strength and field source of the electromagnetic and gravitational fields, impacting the linear momentum, angular momentum, torque, energy, and force and so forth. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1604/1604.05260v1.pdf"}
{"id": "1605.00838", "abstract": "  We study the one-body reduced density matrix of a system of N one-dimensional impenetrable anyons trapped by a harmonic potential. To this purpose we extend two methods developed to tackle related problems, namely the determinant approach and the replica method. While the former is the basis for exact numerical computations at finite N, the latter has the advantage of providing an analytic asymptotic expansion for large N. We show that the first few terms of such expansion are sufficient to reproduce the numerical results to an excellent accuracy even for relatively small N, thus demonstrating the effectiveness of the replica method. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.00838v2.pdf"}
{"id": "1605.01851", "abstract": "  We explore the asymmetric sequential Landau-Zener (LZ) dynamics in an ensemble of interacting Bose condensed two-level atoms coupled with a cavity field. Assuming the couplings between all atoms and the cavity field are identical, the interplay between atom-atom interaction and detuning may lead to a series of LZ transitions. Unlike the conventional sequential LZ transitions, which are symmetric to the zero detuning, the LZ transitions of Bose condensed atoms in a cavity field are asymmetric and sensitively depend on the photon number distribution of the cavity. In LZ processes involving single excitation numbers, both the variance of the relative atom number and the step slope of the sequential population ladder are asymmetric, and the asymmetry become more significant for smaller excitation numbers. Furthermore, in LZ processes involving multiple excitation numbers, there may appear asymmetric population ladders with decreasing step heights. During a dynamical LZ process, due to the atom-cavity coupling, the cavity field shows dynamical collapse and revivals. In comparison with the symmetric LZ transitions in a classical field, the asymmetric LZ transitions in a cavity field originate from the photon-number-dependent Rabi frequency. The asymmetric sequential LZ dynamics of Bose condensed atoms in a cavity field may open up a new way to explore the fundamental many-body physics in coupled atom-photon systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.01851v1.pdf"}
{"id": "1605.02314", "abstract": "  A Full Duplex Base Station (FD-BS) can be used to serve simultaneously two Half-Duplex (HD) Mobile Stations (MSs), one working in the uplink and one in the downlink, respectively. The same functionality can be realized by having two interconnected and spatially separated Half Duplex Base Stations (HD-BSs), which is a scheme termed CoMPflex (CoMP for In-Band Wireless Full Duplex). A FD-BS can be seen as a special case of CoMPflex with separation distance zero. In this paper we study the performance of CoMPflex in a two-dimensional cellular scenario using stochastic geometry and compare it to the one achieved by FD-BSs. By deriving the Cumulative Distribution Functions, we show that CoMPflex brings BSs closer to the MSs they are serving, while increasing the distance between a MS and interfering MSs. Furthermore, the results show that CoMPflex brings benefits over FD-BS in terms of communication reliability. Following the trend of wireless network densification, CoMPflex can be regarded as a method with a great potential to effectively use the dense HD deployments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.02314v1.pdf"}
{"id": "1605.04438", "abstract": "  Experiment shows that dumbbells, placed inside a tilted hollow cylindrical drum that rotates slowly around its axis, climb uphill by forming dynamically stable pairs, seemingly against the pull of gravity. Analysis of this experiment shows that the dynamics takes place in an underlying space which is a curvilinear polyhedron inside a six dimensional manifold, carved out by unilateral constraints that arise from the non-interpenetrability of the dumbbells. The energetics over this polyhedron localizes the configuration point within the close proximity of a corner of the polyhedron. This results into a strong entrapment, which provides the configuration of the dumbbells with its observed shape that leads to its functionality – uphill locomotion. The stability of the configuration is a consequence of the strong entrapment in the corner of the polyhedron. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.04438v2.pdf"}
{"id": "1605.05210", "abstract": "  Motivated by recent interest in their applications, we report a systematic study of Cs atomic properties calculated by a high-precision relativistic all-order method. Excitation energies, reduced matrix elements, transition rates, and lifetimes are determined for levels with principal quantum numbers n ≤ 12 and orbital angular momentum quantum numbers l ≤ 3. Recommended values and estimates of uncertainties are provided for a number of electric-dipole transitions and the electric dipole polarizabilities of the ns, np, and nd states. We also report a calculation of the electric quadrupole polarizability of the ground state. We display the dynamic polarizabilities of the 6s and 7p states for optical wavelengths between 1160 nm and 1800 nm and identify corresponding magic wavelengths for the 6s-7p_1/2, 6s-7p_3/2 transitions. The values of relevant matrix elements needed for polarizability calculations at other wavelengths are provided. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.05210v1.pdf"}
{"id": "1605.05751", "abstract": "  In this note, we establish the 2-D Quantum Inequalities - first proved by Flanagan - for all CFTs with a causal holographic dual. Following the treatment of Kelly & Wall, we establish that the Boundary Causality Condition in an asymptotic AdS spacetime implies the Quantum Inequalities on the boundary. Our results extend easily to curved spacetime and are stable under deformations of the CFT by relevant operators. We discuss higher dimensional generalizations and possible connections to recent bounds on a/c in 4-D CFTs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.05751v1.pdf"}
{"id": "1605.07201", "abstract": "  We propose an algorithm to determine Maximally Localized Wannier Functions (MLWFs). This algorithm, based on recent theoretical developments, does not require any physical input such as initial guesses for the Wannier functions, unlike popular schemes based on the projection method. We discuss how the projection method can fail on fine grids when the initial guesses are too far from MLWFs. We demonstrate that our algorithm is able to find localized Wannier functions through tests on two-dimensional systems, simplified models of semiconductors, and realistic DFT systems by interfacing with the Wannier90 code. We also test our algorithm on the Haldane and Kane-Mele models to examine how it fails in the presence of topological obstructions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.07201v2.pdf"}
{"id": "1605.08373", "abstract": "  Animal cells use traction forces to sense the mechanics and geometry of their environment. Measuring these traction forces requires a workflow combining cell experiments, image processing and force reconstruction based on elasticity theory. Such procedures have been established before mainly for planar substrates, in which case one can use the Green's function formalism. Here we introduce a worksflow to measure traction forces of cardiac myofibroblasts on non-planar elastic substrates. Soft elastic substrates with a wave-like topology were micromolded from polydimethylsiloxane (PDMS) and fluorescent marker beads were distributed homogeneously in the substrate. Using feature vector based tracking of these marker beads, we first constructed a hexahedral mesh for the substrate. We then solved the direct elastic boundary volume problem on this mesh using the finite element method (FEM). Using data simulations, we show that the traction forces can be reconstructed from the substrate deformations by solving the corresponding inverse problem with a L1-norm for the residue and a L2-norm for 0th order Tikhonov regularization. Applying this procedure to the experimental data, we find that cardiac myofibroblast cells tend to align both their shapes and their forces with the long axis of the deformable wavy substrate. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.08373v1.pdf"}
{"id": "1605.08575", "abstract": "  We explore the emergence of persistent infection in a patch of population, where the disease progression of the individuals is given by the SIRS model and an individual becomes infected on contact with another infected individual. We investigate the persistence of contagion qualitatively and quantitatively, under varying degrees of heterogeneity in the initial population. We observe that when the initial population is uniform, consisting of individuals at the same stage of disease progression, infection arising from a contagious seed does not persist. However when the initial population consists of randomly distributed refractory and susceptible individuals, a single source of infection can lead to sustained infection in the population, as heterogeneity facilitates the de-synchronization of the phases in the disease cycle of the individuals. We also show how the average size of the window of persistence of infection depends on the degree of heterogeneity in the initial composition of the population. In particular, we show that the infection eventually dies out when the entire initial population is susceptible, while even a few susceptibles among an heterogeneous refractory population gives rise to a large persistent infected set. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.08575v1.pdf"}
{"id": "1605.08916", "abstract": "  The advent of radioactive ion beam facilities and new detector technologies have opened up new possibilities to investigate the radioactive decays of highly unstable nuclei, in particular the proton emission, α decay and heavy cluster decays from neutron-deficient (or proton-rich) nuclei around the proton drip line. It turns out that these decay measurements can serve as a unique probe for studying the structure of the nuclei involved. On the theoretical side, the development in nuclear many-body theories and supercomputing facilities have also made it possible to simulate the nuclear clusterization and decays from a microscopic and consistent perspective. In this article we would like to review the current status of these structure and decay studies in heavy nuclei, regarding both experimental and theoretical opportunities. We then discuss in detail the recent progress in our understanding of the nuclear α formation probabilities in heavy nuclei and their indication on the underlying nuclear structure. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.08916v1.pdf"}
{"id": "1605.09519", "abstract": "  This paper investigates optimal caching placement for wireless femto-caching network. The average bit error rate (BER) is formulated as a function of caching placement under wireless fading. To minimize the average BER, we propose a greedy algorithm finding optimal caching placement with low computational complexity. Exploiting the property of the optimal caching placement which we derive, the proposed algorithm can be performed over considerably reduced search space. Contrary to the optimal caching placement without consideration of wireless fading aspects, we reveal that optimal caching placement can be reached by balancing a tradeoff between two different gains: file diversity gain and channel diversity gain. Moreover, we also identify the conditions that the optimal placement can be found without running the proposed greedy algorithm and derive the corresponding optimal caching placement in closed form. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.09519v2.pdf"}
{"id": "1606.03261", "abstract": "  Socio-economic inequality is characterized from data using various indices. The Gini (g) index, giving the overall inequality is the most common one, while the recently introduced Kolkata (k) index gives a measure of 1-k fraction of population who possess top k fraction of wealth in the society. Here, we show the relationship between the two indices, using both empirical data and analytical estimates. The significance of their relationship has been discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.03261v2.pdf"}
{"id": "1606.03804", "abstract": "  We investigate the implications of a minimal SU(2) gauge symmetry extension of the standard model at the LHC. To achieve the spontaneous symmetry breaking, a heavy Higgs doublet of the SU(2) is introduced. To obtain an anomaly free model and the decays of new charged gauge bosons, we include a vector-like quark doublet. We also employ a real scalar boson to dictate the heavy Higgs production via the gluon-gluon fusion processes. It is found that the new gauge coupling and the masses of new gauge bosons can be strictly bounded by the electroweak ρ-parameter and dilepton resonance experiments at the LHC. It is found that due to the new charged gauge boson enhancement, the cross sections for a heavy scalar boson to diphoton channel measured by ATLAS and CMS can be easily satisfied when the values of Yukawa couplings are properly taken. Furthermore, by adopting event simulation, we find that the significance of pp→ (γγ)_H+ jet, where the diphoton is from the heavy Higgs decay, can be over 4σ when the luminosity is above 60 fb^-1. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.03804v3.pdf"}
{"id": "1606.04083", "abstract": "  People are often challenged to select one among several alternatives. This situation is present not only in decisions about complex issues, e.g., political or academic choices, but also about trivial ones, as in daily purchases at a supermarket. We tackle this scenario by means of the tools of statistical mechanics. Following this approach, we introduce and analyze a model of opinion dynamics, using a Potts-like state variable to represent the multiple choices, including the “undecided state”, that represents the individuals that do not make a choice. We investigate the dynamics over Erdös-Rényi and Barabási-Albert networks, two paradigmatic classes with the small-world property, and we show the impact of the type of network on the opinion dynamics. Depending on the number of available options q and on the degree distribution of the network of contacts, different final steady states are accessible: from a wide distribution of choices to a state where a given option largely dominates. The abrupt transition between them is consistent with the sudden viral dominance of a given option over many similar ones. Moreover, the probability distributions produced by the model are validated by real data. Finally, we show that the model also contemplates the real situation of overchoice, where a large number of similar alternatives makes the choice process harder and indecision prevail. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.04083v1.pdf"}
{"id": "1606.04213", "abstract": "  We derive gluon fragmentation functions in the Nambu-Jona-Lasinio (NJL) model by treating a gluon as a pair of color lines formed by fictitious quark and anti-quark (qq̅). Gluon elementary fragmentation functions are obtained from the quark and anti-quark elementary fragmentation functions for emitting specific mesons in the NJL model under the requirement that the qq̅ pair maintains in the flavor-singlet state after meson emissions. An integral equation, which iterates the gluon elementary fragmentation functions to all orders, is then solved to yield the gluon fragmentation functions at a model scale. It is observed that these solutions are stable with respect to variation of relevant model parameters, especially after QCD evolution to a higher scale is implemented. We show that the inclusion of the gluon fragmentation functions into the theoretical predictions from only the quark fragmentation functions greatly improves the agreement with the SLD data for the pion and kaon productions in e^+e^- annihilation. Our proposal provides a plausible construct for the gluon fragmentation functions, which are supposed to be null in the NJL model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.04213v2.pdf"}
{"id": "1606.05264", "abstract": "  In this paper we consider the models of the accelerated expanding large scale universe (according to general relativity) containing a generalized holographic dark energy with a Nojiri - Odintsov cut - off. The second component of the darkness is assumed to be the pressureless cold dark matter according to observed symmetries of the large scale universe. Moreover, we assume specific forms of the interaction between these two components and besides the cosmographic analysis, we discuss appropriate results from Om and Om3 analysis and organize a closer look to the models via the statefinder hierarchy analysis, too. In this way we study mainly impact of the interaction on the dynamics of the background of our universe (within specific forms of interaction). To complete the cosmographic analysis, the present day values of the statefinder parameters (r,s) and (ω^'_de, ω_de) has been estimated for all cases and the validity of the generalized second law of thermodynamics is demonstrated. Our study showed that theoretical results from considered phenomenological models are consistent with the available observational data and symmetries. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.05264v1.pdf"}
{"id": "1606.05314", "abstract": "  We discuss some current problems in the relationship between elementary particle physics and gravitation, i.e., in the subject investigated by Prof. K. P. Staniukovich half a century ago. Specifically, the inflationary stage of the Universe evolution, originating from the vacuum polarization and particle creation, corrections to Newton's gravitational law due to exchange of light elementary particles or spontaneous compactification of extra dimensions, and constraints on the parameters of axions as probable constituents of dark matter in our Universe are considered. It is pointed out that presently the relationship between elementary particles and gravitation has become an experimental science, and many experiments, directed towards resolution of all related problems, are performed in many countries. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.05314v1.pdf"}
{"id": "1606.05954", "abstract": "  In this paper, we study a diamond-relay channel where the source is connected to M relays through orthogonal links and the relays transmit to the destination over a wireless multiple-access channel in the presence of an eavesdropper. The eavesdropper not only observes the relay transmissions through another multiple-access channel, but also observes a certain number of source-relay links. The legitimate terminals know neither the eavesdropper's channel state information nor the location of source-relay links revealed to the eavesdropper except the total number of such links.   For this wiretapped diamond-relay channel, we establish the optimal secure degrees of freedom. In the achievability part, our proposed scheme uses the source-relay links to transmit a judiciously constructed combination of message symbols, artificial noise symbols as well as fictitious message symbols associated with secure network coding. The relays use a combination of beamforming and interference alignment in their transmission scheme. For the converse part, we take a genie-aided approach assuming that the location of wiretapped links is known. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.05954v1.pdf"}
{"id": "1606.06142", "abstract": "  The tagging of on-line content with informative keywords is a widespread phenomenon from scientific article repositories through blogs to on-line news portals. In most of the cases, the tags on a given item are free words chosen by the authors independently. Therefore, relations among keywords in a collection of news items is unknown. However, in most cases the topics and concepts described by these keywords are forming a latent hierarchy, with the more general topics and categories at the top, and more specialised ones at the bottom. Here we apply a recent, cooccurrence-based tag hierarchy extraction method to sets of keywords obtained from four different on-line news portals. The resulting hierarchies show substantial differences not just in the topics rendered as important (being at the top of the hierarchy) or of less interest (categorised low in the hierarchy), but also in the underlying network structure. This reveals discrepancies between the plausible keyword association frameworks in the studied news portals. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1606/1606.06142v1.pdf"}
{"id": "1607.03532", "abstract": "  Gradient-driven diffusion in crowded, multicomponent mixtures is a topic of high interest because of its role in biological processes such as transport in cell membranes. In partially phase-separated solutions, gradient-driven diffusion affects microstructure, which in turn affects diffusivity; a key question is how this complex coupling controls both transport and pattern formation. To examine these mechanisms, we study a two-dimensional multi-component lattice gas model, where \"tracer\" molecules diffuse between a source and a sink separated by a solution of sticky \"crowder\" molecules that cluster to form dynamically evolving obstacles. In the high temperature limit, crowders and tracers are miscible and transport may be predicted analytically. At intermediate temperatures, crowders phase separate into clusters that drift toward the tracer sink. As a result, steady-state tracer diffusivity depends non-monotonically on both temperature and crowder density and we observe a variety of complex microstructures. In the low temperature limit, crowders rapidly aggregate to form obstacles that are kinetically arrested; if crowder density is near the percolation threshold, resulting tracer diffusivity shows scaling behavior with the same scaling exponent as the random resistor network model. Though highly idealized, this simple model reveals fundamental mechanisms governing coupled gradient-driven diffusion, phase separation, and microstructural evolution in crowded solutions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1607/1607.03532v3.pdf"}
{"id": "1608.00073", "abstract": "  Solar coronal radio bursts are enhanced radio emission excited by energetic electrons accelerated during solar eruptions, studies on which are important for investigating the origin and physical mechanism of energetic particles and further diagnosing coronal parameters. Earlier studies suffered from a lack of simultaneous high-quality imaging data of the radio burst and the eruptive structure in the inner corona. Here we present a study on a complex solar radio eruption consisting of a type II and three reversely-drifting type III bursts, using simultaneous EUV and radio imaging data. It is found that the type II burst is closely associated with a propagating and evolving CME-driven EUV shock structure, originated initially at the northern shock flank and later transferred to the top part of the shock. This source transfer is co-incident with the presence of shock decay and enhancing signatures observed at the corresponding side of the EUV front. The electron energy accelerated by the shock at the flank is estimated to be ∼ 0.3 c by examining the imaging data of the fast-drifting herringbone structure of the type II burst. The reversely-drifting type III sources are found to be within the ejecta and correlated with a likely reconnection event therein. Implications on further observational studies and relevant space-weather forecasting techniques are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.00073v1.pdf"}
{"id": "1608.00087", "abstract": "  We suggest a scalar singlet extension of the standard model, in which the multiple-point principle (MPP) condition of a vanishing Higgs potential at the Planck scale is realized. Although there have been lots of attempts to realize the MPP at the Planck scale, the realization with keeping naturalness is quite difficult. Our model can easily achieve the MPP at the Planck scale without large Higgs mass corrections. It is worth noting that the electroweak symmetry can be radiatively broken in our model. In the naturalness point of view, the singlet scalar mass should be of O(1)  TeV or less. We also consider right-handed neutrino extension of the model for neutrino mass generation. The model does not affect the MPP scenario, and might keep the naturalness with the new particle mass scale beyond TeV, thanks to accidental cancellation of Higgs mass corrections. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.00087v2.pdf"}
{"id": "1608.00120", "abstract": "  To meet the ever-increasing demands on higher throughput and better network delay performance, 60 GHZ networking is proposed as a promising solution for the next generation of wireless communications. To successfully deploy such networks, its important to understand their performance first. However, due to the unique fading characteristic of the 60 GHz channel, the characterization of the corresponding service process, offered by the channel, using the conventional methodologies may not be tractable. In this work, we provide an alternative approach to derive a closed-form expression that characterizes the cumulative service process of the 60 GHz channel in terms of the moment generating function (MGF) of its instantaneous channel capacity. We then use this expression to derive probabilistic upper bounds on the backlog and delay that are experienced by a flow traversing this network, using results from the MGF-based network calculus. The computed bounds are validated using simulation. We provide numerical results for different networking scenarios and for different traffic and channel parameters and we show that the 60 GHz wireless network is capable of satisfying stringent quality-of-Service (QoS) requirements, in terms of network delay and reliability. With this analysis approach at hand, a larger scale 60 GHz network design and optimization is possible. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.00120v3.pdf"}
{"id": "1608.00138", "abstract": "  PSO is a widely recognized optimization algorithm inspired by social swarm. In this brief we present a heterogeneous strategy particle swarm optimization (HSPSO), in which a proportion of particles adopt a fully informed strategy to enhance the converging speed while the rest are singly informed to maintain the diversity. Our extensive numerical experiments show that HSPSO algorithm is able to obtain satisfactory solutions, outperforming both PSO and the fully informed PSO. The evolution process is examined from both structural and microscopic points of view. We find that the cooperation between two types of particles can facilitate a good balance between exploration and exploitation, yielding better performance. We demonstrate the applicability of HSPSO on the filter design problem. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.00138v1.pdf"}
{"id": "1608.02006", "abstract": "  We present a second-order N-electron valence state perturbation theory (NEVPT2) based on a density matrix renormalization group (DMRG) reference wave function that exploits a Cholesky decomposition of the two-electron repulsion integrals (CD-DMRG-NEVPT2). With a parameter-free multireference perturbation theory approach at hand, the latter allows us to efficiently describe static and dynamic correlation in large molecular systems. We demonstrate the applicability of CD-DMRG-NEVPT2 for spin-state energetics of spin-crossover complexes involving calculations with more than 1000 atomic basis functions. We first assess in a study of a heme model the accuracy of the strongly- and partially-contracted variant of CD-DMRG-NEVPT2 before embarking on resolving a controversy about the spin ground state of a cobalt tropocoronand complex. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.02006v1.pdf"}
{"id": "1608.02632", "abstract": "  In dispersive media, hydrodynamic singularities are resolved by coherent wavetrains known as dispersive shock waves (DSWs). Only dynamically expanding, temporal DSWs are possible in one-dimensional media. The additional degree of freedom inherent in two-dimensional media allows for the generation of time-independent DSWs that exhibit spatial expansion. Spatial oblique DSWs, dispersive analogs of oblique shocks in classical media, are constructed utilizing Whitham modulation theory for a class of nonlinear Schrödinger boundary value problems. Self-similar, simple wave solutions of the modulation equations yield relations between the DSW's orientation and the upstream/downstream flow fields. Time dependent numerical simulations demonstrate a convective or absolute instability of oblique DSWs in supersonic flow over obstacles. The convective instability results in an effective stabilization of the DSW. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.02632v1.pdf"}
{"id": "1608.03686", "abstract": "  Sparse reduced-rank regression is an important tool to uncover meaningful dependence structure between large numbers of predictors and responses in many big data applications such as genome-wide association studies and social media analysis. Despite the recent theoretical and algorithmic advances, scalable estimation of sparse reduced-rank regression remains largely unexplored. In this paper, we suggest a scalable procedure called sequential estimation with eigen-decomposition (SEED) which needs only a single top-r singular value decomposition to find the optimal low-rank and sparse matrix by solving a sparse generalized eigenvalue problem. Our suggested method is not only scalable but also performs simultaneous dimensionality reduction and variable selection. Under some mild regularity conditions, we show that SEED enjoys nice sampling properties including consistency in estimation, rank selection, prediction, and model selection. Numerical studies on synthetic and real data sets show that SEED outperforms the state-of-the-art approaches for large-scale matrix estimation problem. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.03686v1.pdf"}
{"id": "1608.04413", "abstract": "  Recent studies have found a positive correlation between the star-formation rate of galaxies and their gamma-ray luminosity. Galaxies with a high star-formation rate are expected to produce a large amount of high-energy cosmic rays, which emit gamma-rays when interacting with the interstellar medium and radiation fields. We search for gamma-ray emission from a sample of galaxies within and beyond the Local Group with data from the LAT instrument onboard the Fermi satellite. We exclude recently detected galaxies (NGC 253, M82, NGC 4945, NGC 1068, NGC 2146, Arp 220) and use seven years of cumulative Pass 8 data from the LAT in the 100 MeV to 100 GeV range. No new detections are seen in the data and upper limits for the gamma- ray fluxes are calculated. The correlation between gamma-ray luminosity and infrared luminosity for galaxies obtained using our new upper limits is in agreement with a previously published correlation, but the new upper limits imply that some galaxies are not as efficient gamma-ray emitters as previously thought. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.04413v1.pdf"}
{"id": "1608.04426", "abstract": "  Unsupervised neural networks, such as restricted Boltzmann machines (RBMs) and deep belief networks (DBNs), are powerful tools for feature selection and pattern recognition tasks. We demonstrate that overfitting occurs in such models just as in deep feedforward neural networks, and discuss possible regularization methods to reduce overfitting. We also propose a \"partial\" approach to improve the efficiency of Dropout/DropConnect in this scenario, and discuss the theoretical justification of these methods from model convergence and likelihood bounds. Finally, we compare the performance of these methods based on their likelihood and classification error rates for various pattern recognition data sets. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.04426v4.pdf"}
{"id": "1608.05227", "abstract": "  We demonstrate the interplay between quantum well states in Pd and the magnetic anisotropy in Pd/Co/Cu(001) by combined scanning tunneling spectroscopy (STS) and magneto optical Kerr effect (MOKE) measurements. Low temperature scanning tunneling spectroscopy reveals occupied and unoccupied quantum well states (QWS) in atomically flat Pd films on Co/Cu(001). These states give rise to sharp peaks in the differential conductance spectra. A quantitative analysis of the spectra reveals the electronic dispersion of the Pd(001) d-band (Δ_5-type) along the Γ-X direction. In-situ MOKE experiments on Pd/Co/Cu(1, 1, 13) uncover a periodic variation of the in-plane uniaxial magnetic anisotropy as a function of Pd thickness with a period of 6 atomic layers Pd. STS shows that QWS in Pd cross the Fermi level with the same periodicity of 6 atomic layers. Backed by previous theoretical work we ascribe the variation of the magnetic anisotropy in Co to QWS in the Pd overlayer. Our results suggest a novel venue towards tailoring uniaxial magnetic anisotropy of ferromagnetic films by exploiting QWS in an adjacent material with large spin-orbit coupling. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.05227v1.pdf"}
{"id": "1608.06108", "abstract": "  We propose a Bayesian model for extracting sleep patterns from smartphone events. Our method is able to identify individuals' daily sleep periods and their evolution over time, and provides an estimation of the probability of sleep and wake transitions. The model is fitted to more than 400 participants from two different datasets, and we verify the results against ground truth from dedicated armband sleep trackers. We show that the model is able to produce reliable sleep estimates with an accuracy of 0.89, both at the individual and at the collective level. Moreover the Bayesian model is able to quantify uncertainty and encode prior knowledge about sleep patterns. Compared with existing smartphone-based systems, our method requires only screen on/off events, and is therefore much less intrusive in terms of privacy and more battery-efficient. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.06108v1.pdf"}
{"id": "1608.06509", "abstract": "  The paper deals with collapse dynamics of a spherically symmetric massive star in the framework of non-equilibrium themodynamic prescription through particle creation mechanism. The matter content in the star is in the form of perfect uid with barotropic equation of state and the dissipative phenomena due to non-equilibrium thermodynamics is in the form of bulk viscosity. For simplicity, the thermodynamic system is chosen to be adiabatic (i.e., isentropic) so that the effective bulk viscous pressure is linearly related to the particle creation rate. As a result, the evolution of the collapsing star also depends on the particle creation rate. By proper choice of creation rate as a function of the Hubble parameter, it is found that the end state of the collapse may be either a black hole or a naked singularity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.06509v2.pdf"}
{"id": "1608.07224", "abstract": "  Gender differences in collaborative research have received little attention when compared with the growing importance that women hold in academia and research. Unsurprisingly, most of bibliometric databases have a strong lack of directly available information by gender. Although empirical-based network approaches are often used in the study of research collaboration, the studies about the influence of gender dissimilarities on the resulting topological outcomes are still scarce. Here, networks of scientific subjects are used to characterize patterns that might be associated to five categories of authorships which were built based on gender. We find enough evidence that gender imbalance in scientific authorships brings a peculiar trait to the networks induced from papers published in Web of Science (WoS) indexed journals of Economics over the period 2010-2015 and having at least one author affiliated to a Portuguese institution. Our results show the emergence of a specific pattern when the network of co-occurring subjects is induced from a set of papers exclusively authored by men. Such a male-exclusive authorship condition is found to be the solely responsible for the emergence that particular shape in the network structure. This peculiar trait might facilitate future network analyses of research collaboration and interdisciplinarity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.07224v2.pdf"}
{"id": "1609.00669", "abstract": "  The analytic structure of scattering amplitudes is restricted by Steinmann relations, which enforce the vanishing of certain discontinuities of discontinuities. We show that these relations dramatically simplify the function space for the hexagon function bootstrap in planar maximally supersymmetric Yang-Mills theory. Armed with this simplification, along with the constraints of dual conformal symmetry and Regge exponentiation, we obtain the complete five-loop six-particle amplitude. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.00669v2.pdf"}
{"id": "1609.02106", "abstract": "  The recent star formation history (SFH) in the outer disk of NGC 300 is presented through the analysis of color magnitude diagrams (CMDs). We analyze resolved stellar photometry by creating CMDs from four Hubble Space Telescope fields containing a combination of images from the Advanced Camera for Surveys and the UVIS imager aboard the Wide Field Camera 3. From the best models of these CMDs, we derive the SFH in order to extract the young stellar component for the past 200 Myrs. We find that the young stellar disk of NGC 300 is unbroken out to at least ∼8 scale lengths (including an upper limit out to ∼10 scale lengths) with r_s = 1.4 ± 0.1 kpc, which is similar to the total stellar surface brightness profile. This unbroken profile suggests that NGC 300 is undisturbed, similar to the isolated disk galaxy NGC 2403. We compare the environments of NGC 300, NGC 2403, and M33 along with the properties of the gas and stellar disks. We find that the disturbed HI outer disk morphology is not accompanied by a break in the young stellar disk. This may indicate that processes which affect the outer HI morphology may not leave an imprint on the young stellar disk. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.02106v1.pdf"}
{"id": "1609.03639", "abstract": "  Natures of progenitors of type Ia Supernovae (SNe Ia) have not yet been clarified. There has been long and intensive discussion on whether the so-called single degenerate (SD) scenario or the double degenerate (DD) scenario, or anything else, could explain a major population of SNe Ia, but the conclusion has not yet been reached. With rapidly increasing observational data and new theoretical ideas, the field of studying the SN Ia progenitors has been quickly developing, and various new insights have been obtained in recent years. This article aims at providing a summary of the current situation regarding the SN Ia progenitors, both in theory and observations. It seems difficult to explain the emerging diversity seen in observations of SNe Ia by a single population, and we emphasize that it is important to clarify links between different progenitor scenarios and different sub-classes of SNe Ia. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.03639v1.pdf"}
{"id": "1609.03881", "abstract": "  Dzyaloshinskii-Moriya (DM) interaction has been proven to excite entanglement of spin systems, enhancing the capability of realizing various quantum tasks such as teleportation. In this work, we consider the DM interaction -to the best of our knowledge, for the first time in quantum game theory. We study the winning probability of magic square game played with the thermal entangled state of spin models under external magnetic fields and DM interaction. We analytically show that although DM interaction excites the entanglement of the system as expected, it surprizingly reduces the winning probability of the game, acting like temperature or magnetic fields, and also show that the effects of DM interaction and inhomogeneous magnetic field on the winning probability are identical. In addition, we show that XXZ model is considerably more robust than XX model against destructive effects. Our results can open new insights for quantum information processing with spin systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.03881v1.pdf"}
{"id": "1609.04119", "abstract": "  The full solution of the optimization problem giving the Gaussian capacity of the single-mode fiducial Gaussian quantum channel is provided. Since it was shown that the Gaussian capacity of an arbitrary (phase-sensitive or insensitive) single-mode Gaussian quantum channel is equal to the Gaussian capacity of this fiducial channel, the solution presented in this work can be regarded as universal. The analytical study of this solution, below and above the energy threshold, shows that the dependence of the Gaussian capacity on the environment noise squeezing is not monotonic. In particular, the capacity may have a saddle point, one or two extrema at finite squeezing, or be a monotonically increasing function of the squeezing parameter. The exact dependence is defined by the determinant of the noise covariance matrix and by the transmissivity (or gain) of the fiducial Gaussian channel. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.04119v2.pdf"}
{"id": "1609.06150", "abstract": "  Electron transport is studied in surface oxidized single-crystal copper thin films with a thickness of up to 5.6 nm by applying density functional theory and density functional tight binding methods to determine electron transport properties within the ballistic regime. The variation of the electron transmission as a function of film thickness as well as the different contributions to the overall electron transmission as a function of depth into the the films is examined. Transmission at the oxidized copper film surfaces is found to be universally low. Films with thickness greater than 2.7 nm exhibit a similar behavior in local transmission per unit area with depth from the film surface; transmission per unit area initially increases rapidly and then plateaus at a depth of approximately 0.35-0.5 nm away from the surface, dependent on surface facet. Unstrained films tend to exhibit a higher transmission per unit area than corresponding films under tensile strain. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.06150v2.pdf"}
{"id": "1609.09013", "abstract": "  We present a 𝐤·𝐩 theory of photonic crystals containing gain and loss in which the gain and loss are added to separate primitive cells of the underlying Hermitian system, thereby creating a supercell photonic crystal. We show that the supercell bands of this system can merge outward from the degenerate contour formed from folding the bands of the underlying Hermitian system into the supercell Brillouin zone, but that other accidental degeneracies in the band structure of the underlying Hermitian system do not yield band merging behavior. Finally, we show that the modal coupling matrix in PhCs with balanced gain and loss is trace-less, and thus the imaginary components of the eigenvalues can only move relative to one another as the strength of the gain and loss is varied, without any collective motion. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.09013v1.pdf"}
{"id": "1610.00654", "abstract": "  We have performed a complete study of self-dual configurations in a CPT-odd and Lorentz-violating gauged O(3) nonlinear sigma model. We have consistently implemented the Bogomol'nyi-Prasad-Sommerfield (BPS) formalism and obtained the correspondent differential first-order equations describing electrically charged self-dual configurations. The total energy and magnetic flux of the vortices, besides being proportional to the winding number, also depend explicitly on the Lorentz-violating coefficients belonging to the sigma sector. The total electrical charge is proportional to the magnetic flux such as it occurs in Chern-Simons models. The Lorentz violation in the sigma sector allows one to interpolate between Lorentz-violating versions of some sigma models: the gauged O(3) sigma model and the Maxwell-Chern-Simons O(3) sigma model. The Lorentz violation enhances the amplitude of the magnetic field and BPS energy density near the origin, augmenting the deviation in relation to the solutions deprived of Lorentz violation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.00654v1.pdf"}
{"id": "1610.01022", "abstract": "  We present a comprehensive analysis of the form and interaction of dipolar bright solitons across the full parameter space afforded by dipolar Bose-Einstein condensates, revealing the rich behaviour introduced by the non-local nonlinearity. Working within an effective one-dimensional description, we map out the existence of the soliton solutions and show three collisional regimes: free collisions, bound state formation and soliton fusion. Finally, we examine the solitons in their full three-dimensional form through a variational approach; along with regimes of instability to collapse and runaway expansion, we identify regimes of stability which are accessible to current experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.01022v2.pdf"}
{"id": "1610.01759", "abstract": "  Families of soliton pairs, namely vector solitons, are found within the context of a coupled nonlocal nonlinear Schrodinger system of equations, as appropriate for modeling beam propagation in nematic liquid crystals. In the focusing case, bright soliton pairs have been found to exist provided their amplitudes satisfy a specific condition. In our analytical approach, focused on the defocusing regime, we rely on a multiscale expansion methods, which reveals the existence of dark-dark and antidark-antidark solitons, obeying an effective Korteweg-de Vries equation, as well as dark-bright solitons, obeying an effective Mel'nikov system. These pairs are discriminated by the sign of a constant that links all physical parameters of the system to the amplitude of the stable continuous wave solutions, and, much like the focusing case, the solitons' amplitudes are linked leading to mutual guiding. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.01759v1.pdf"}
{"id": "1610.04899", "abstract": "  An exact analytical solution for the Bohr Hamiltonian with an energy dependent Coulomb-like γ-unstable potential is presented. Due to the linear energy dependence of the potential's coupling constant, the corresponding spectrum in the asymptotic limit of the slope parameter resembles the spectral structure of the spherical vibrator, however with a different state degeneracy. The parameter free energy spectrum as well as the transition rates for this case are given in closed form and duly compared with those of the harmonic U(5) dynamical symmetry. The model wave functions are found to exhibit properties that can be associated to shape coexistence. A possible experimental realization of the model is found in few medium nuclei with a very low second 0^+ state known to exhibit competing prolate, oblate and spherical shapes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.04899v1.pdf"}
{"id": "1610.06142", "abstract": "  Analysis of the saturation of the Kelvin-Helmholtz (KH) instability is undertaken to determine the extent to which the conjugate linearly stable mode plays a role. For a piecewise-continuous mean flow profile with constant shear in a fixed layer, it is shown that the stable mode is nonlinearly excited, providing an injection-scale sink of the fluctuation energy similar to what has been found for gyroradius-scale drift-wave turbulence. Quantitative evaluation of the contribution of the stable mode to the energy balance at the onset of saturation shows that nonlinear energy transfer to the stable mode is as significant as energy transfer to small scales in balancing energy injected into the spectrum by the instability. The effect of the stable mode on momentum transport is quantified by expressing the Reynolds stress in terms of stable and unstable mode amplitudes at saturation, from which it is found that the stable mode can produce a sizable reduction in the momentum flux. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.06142v4.pdf"}
{"id": "1610.07433", "abstract": "  We present the reduced dynamics of a bead in a Rouse chain which is submerged in a bath containing a driving agent that renders it out-of-equilibrium. We first review the generalized Langevin equation of the middle bead in an equilibrated bath. Thereafter, we introduce two driving forces. Firstly, we add a constant force that is applied to the first bead of the chain. We investigate how the generalized Langevin equation changes due to this perturbation for which the system evolves towards a new equilibrium state after some time. Secondly, we consider the case of stochastic active forces which will drive the system to a nonequilibrium state. Including these active forces results in a frenetic contribution to the second fluctuation-dissipation relation, in accord with a recent extension of the fluctuation-dissipation relation to nonequilibrium. The form of the frenetic term is analysed for the specific case of Gaussian, exponentially correlated active forces. We also discuss the resulting rich dynamics of the middle bead in which various regimes of normal diffusion, subdiffusion and superdiffusion can be present. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.07433v1.pdf"}
{"id": "1610.08136", "abstract": "  Models such as latent semantic analysis and those based on neural embeddings learn distributed representations of text, and match the query against the document in the latent semantic space. In traditional information retrieval models, on the other hand, terms have discrete or local representations, and the relevance of a document is determined by the exact matches of query terms in the body text. We hypothesize that matching with distributed representations complements matching with traditional local representations, and that a combination of the two is favorable. We propose a novel document ranking model composed of two separate deep neural networks, one that matches the query and the document using a local representation, and another that matches the query and the document using learned distributed representations. The two networks are jointly trained as part of a single neural network. We show that this combination or `duet' performs significantly better than either neural network individually on a Web page ranking task, and also significantly outperforms traditional baselines and other recently proposed models based on neural networks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.08136v1.pdf"}
{"id": "1610.08265", "abstract": "  We study the confinement-deconfinement transition in SU(2) gauge theory in the presence of massless bosons using lattice Monte Carlo simulations. The nature of this transition depends on the temporal extent (N_τ) of the Euclidean lattice. We find that the transition is a cross-over for N_τ=2,4 and second order with 3D Ising universality class for N_τ=8. Our results show that the second order transition is accompanied by realization of the Z_2 symmetry. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.08265v2.pdf"}
{"id": "1610.08891", "abstract": "  We study a three-body system, formed by a light particle and two identical heavy dipoles, in two dimensions in the Born-Oppenheimer approximation. We present the analytic light-particle wave function resulting from an attractive zero-range potential between the light and each of the heavy particles. It expresses the large-distance universal properties which must be reproduced by all realistic short-range interactions. We calculate the three-body spectrum for zero heavy-heavy interaction as a function of light to heavy mass ratio. We discuss the relatively small deviations from Coulomb estimates and the degeneracies related to radial nodes and angular momentum quantum numbers. We include a repulsive dipole-dipole interaction and investigate the three-body solutions as functions of strength and dipole direction. Avoided crossings occur between levels localized in the emerging small and large-distance minima, respectively. The characteristic exchange of properties such as mean square radii are calculated. Simulation of quantum information transfer is suggested. For large heavy-heavy particle repulsion all bound states have disappeared into the continuum. The corresponding critical strength is inversely proportional to the square of the mass ratio, far from the linear dependence from the Landau criterion. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.08891v2.pdf"}
{"id": "1610.09550", "abstract": "  We utilize a homodyne detection technique to achieve a new sensitivity limit for atom-based, absolute radio-frequency electric field sensing of 5 μ V cm^-1 Hz^-1/2. A Mach-Zehnder interferometer is used for the homodyne detection. With the increased sensitivity, we investigate the dominant dephasing mechanisms that affect the performance of the sensor. In particular, we present data on power broadening, collisional broadening and transit time broadening. Our results are compared to density matrix calculations. We show that photon shot noise in the signal readout is currently a limiting factor. We suggest that new approaches with superior readout with respect to photon shot noise are needed to increase the sensitivity further. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.09550v1.pdf"}
{"id": "1611.00723", "abstract": "  Socio-economic inequality is measured using various indices. The Gini (g) index, giving the overall inequality is the most commonly used, while the recently introduced Kolkata (k) index gives a measure of 1-k fraction of population who possess top k fraction of wealth in the society. This article reviews the character of such inequalities, as seen from a variety of data sources, the apparent relationship between the two indices, and what toy models tell us. These socio-economic inequalities are also investigated in the context of man-made social conflicts or wars, as well as in natural disasters. Finally, we forward a proposal for an international institution with sufficient fund for visitors, where natural and social scientists from various institutions of the world can come to discuss, debate and formulate further developments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.00723v2.pdf"}
{"id": "1611.00844", "abstract": "  A modification to the L_1 control framework for uncertain systems with actuator delay is presented. Specifically, a time delay is introduced in the control input of the state predictor to compensate for the destabilizing effect of input delay in the plant. For this modified framework, the analysis shows that the output of the adaptive system closely follows the behavior of a suitably defined, nonadaptive, stable reference system provided that a delay-dependent stability condition is satisfied and the adaptive gain is chosen sufficiently large. The set of combinations of input delay and compensation delay for which the stability condition is satisfied contains an open set of pairs of positive values provided that a filter bandwidth, characteristic of L_1 adaptive control is chosen sufficiently large. The efficacy of the delay compensation is illustrated by a simple example. A numerical continuation is also performed to explore the stability region for a case where this can be approximated a priori. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.00844v1.pdf"}
{"id": "1611.01740", "abstract": "  Since quantum coherence is an undoubted characteristic trait of quantum physics, the quantification and application of quantum coherence has been one of the long-standing central topics in quantum information science. Within the framework of a resource theory of quantum coherence proposed recently, a fiducial basis should be pre-selected for characterizing the quantum coherence in specific circumstances, namely, the quantum coherence is a basis-dependent quantity. Therefore, a natural question is raised: what are the maximum and minimum coherences contained in a certain quantum state with respect to a generic basis? While the minimum case is trivial, it is not so intuitive to verify in which basis the quantum coherence is maximal. Based on the coherence measure of relative entropy, we indicate the particular basis in which the quantum coherence is maximal for a given state, where the Fourier matrix (or more generally, complex Hadamard matrices) plays a critical role in determining the basis. Intriguingly, though we can prove that the basis associated with the Fourier matrix is a stationary point for optimizing the l_1 norm of coherence, numerical simulation shows that it is not a global optimal choice. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.01740v2.pdf"}
{"id": "1611.02265", "abstract": "  Diffuse gamma-ray emission from interstellar clouds results largely from cosmic ray (CR) proton collisions with ambient gas, regardless of the gas state, temperature, or dust properties of the cloud. The interstellar medium is predominantly transparent to both CRs and gamma-rays, so GeV emission is a unique probe of the total gas column density. The gamma-ray emissivity of a cloud of known column density is then a measure of the impinging CR population and may be used to map the kpc-scale CR distribution in the Galaxy. To this end, we test a number of commonly used column density tracers to evaluate their effectiveness in modeling the GeV emission from the relatively quiescent, nearby ρ Ophiuchi molecular cloud. We confirm that both  and an appropriate H_2 tracer are required to reproduce the total gas column densities probed by diffuse gamma-ray emisison. We find that the optical depth at 353 GHz τ_353 from Planck reproduces the gamma-ray data best overall based on the test statistic across the entire region of interest, but near infrared stellar extinction also performs very well, with smaller spatial residuals in the densest parts of the cloud. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.02265v1.pdf"}
{"id": "1611.09552", "abstract": "  Artificial gauge fields are versatile tools that allow to influence the dynamics of ultracold atoms in Bose-Einstein condensates. Here we discuss a method of artificial gauge field generation stemming from the evanescent fields of the curved surface of an optical nanofibre. The exponential decay of the evanescent fields leads to large gradients in the generalized Rabi frequency and therefore to the presence of geometric vector and scalar potentials. By solving the Gross-Pitaevskii equation in the presence of the artificial gauge fields originating from the fundamental HE_11 mode of the fibre, we show that vortex rings can be created in a controlled manner. We also calculate the magnetic fields resulting from the higher order HE_21, TE_01, and TM_01 modes and compare them to the fundamental HE_11 mode. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.09552v2.pdf"}
{"id": "1611.09870", "abstract": "  In this paper we analytically extract the odd azimuthal anisotropy in the Classical Yang-Mills equations for the Glasma for pA collisions. We compute the first non-trivial term in the expansion of the proton sources of color charge. The computation is valid in the limit of a large nucleus when the produced particle momenta are larger than the saturation momentum of the proton. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.09870v4.pdf"}
{"id": "1611.10357", "abstract": "  The empirical distribution function of citations to journal articles (EDF for short) can become the fundamental tool for analyzing the scientific journals. Endeavors at making bibliometric analysis independent of the intuition of average citation levels have led us to the study of qualitative properties of physics journals in the functional space of EDFs. We show that the structure of this space establishes the connections and relationships that determine the essential features of physics journals. The research provides an analysis of 240 physics journals indexed in Journal Citation Reports 2015. The relevance of EDFs clustering is discussed. Our findings reveal four-cluster space of physics journals. The space brings to light the essential distinctions between physics journals and shows different level of influence of scientific publishers belonging to different types (professional physics societies, transnational and local publishers). The study of EDFs grouped by publishers reveals two binary oppositions that structure relations between them: \"global — local\" publishers and \"high cited — low cited\" publishers. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.10357v3.pdf"}
{"id": "1612.02680", "abstract": "  For years, the biggest unspeakable in quantum theory has been why quantum theory and what is quantum theory telling us about the world. Recent efforts are unveiling a surprisingly simple answer. Here we show that two characteristic limits of quantum theory, the maximum violations of Clauser-Horne-Shimony-Holt and Klyachko-Can-Binicioğlu-Shumovsky inequalities, are enforced by a simple principle. The effectiveness of this principle suggests that non-realism is the key that explains why quantum theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.02680v1.pdf"}
{"id": "1612.03395", "abstract": "  We theoretically study the magnetoresistance (MR) of two-dimensional massless Dirac electrons as found on the surface of three-dimensional topological insulators (3D TIs) that is capped by a ferromagnetic insulator (FI). We calculate charge and spin transport by Kubo and Boltzmann theories, taking into account the ladder-vertex correction and the in-scattering due to normal and magnetic disorder. The induced exchange splitting is found to generate an electric conductivity that depends on the magnetization orientation, but its form is very different from both the anisotropic and spin Hall MR. The in-plane MR vanishes identically for non-magnetic disorder, while out-of-plane magnetizations cause a large MR ratio. On the other hand, we do find an in-plane MR and planar Hall effect in the presence of magnetic disorder aligned with the FI magnetization. Our results may help understand recent transport measurements on TI|FI systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.03395v2.pdf"}
{"id": "1612.09555", "abstract": "  The representation of the wave functions of the nucleon resonances within a relativistic framework is a complex task. In a nonrelativistic framework the orthogonality between states can be imposed naturally. In a relativistic generalization, however, the derivation of the orthogonality condition between states can be problematic, particularly when the states have different masses. In this work we study the N(1520) and N(1535) states using a relativistic framework. We considered wave functions derived in previous works, but impose the orthogonality between the nucleon and resonance states using the properties of the nucleon, ignoring the difference of masses between the states (semirelativistic approximation). The N(1520) and N(1535) wave functions are then defined without any adjustable parameters and are used to make predictions for the valence quark contributions to the transition form factors. The predictions compare well with the data particularly for high momentum transfer, where the dominance of the quark degrees of freedom is expected. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.09555v3.pdf"}
{"id": "1701.00535", "abstract": "  We examine the dynamics of chiral states of chiral molecules with high tunneling rates in dilute and condensed phases in the context of time-dependent perturbation theory. The chiral molecule is effectively described by an asymmetric double-well potential, whose asymmetry is a measure of chiral interactions. The dilute and condensed phases are conjointly described by a collection of harmonic oscillators but respectively with temperature-dependent sub-ohmic and temperature-independent ohmic spectral densities. We examine our method quantitatively by applying the dynamics to isotopic ammonia molecule, NHDT, in an inert background gas (as the dilute phase) and in water (as the condensed phase). As different spectral densities implies, the extension of the dynamics from the dilute phase to the condensed phase is not trivial. While the dynamics in the dilute phase leads to racemization, the chiral interactions in the condensed phase induce the quantum Zeno effect. Moreover, contrary to the condensed phase, the short-time dynamics in the dilute phase is sensitive to the initial state of the chiral molecule and to the strength of the coupling between the molecule and the environment. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.00535v1.pdf"}
{"id": "1701.01423", "abstract": "  The Hennings invariant for the small quantum group associated to an arbitrary simple Lie algebra at a root of unity is shown to agree with Jones- Witten-Reshetikhin-Turaev invariant arising from Chern-Simons filed theory for the same Lie algebra and the same root of unity on all integer homol- ogy three-spheres, at roots of unity where both are defined. This partially generalizes the work of Chen, et al. ([CYZ12, CKS09]) which relates the Hennings and Chern-Simons invariants for SL(2) and SO(3) for arbitrary rational homology three-spheres. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.01423v2.pdf"}
{"id": "1701.01997", "abstract": "  We investigate the Zeno dynamics of the optical rogue waves. Considering their usage in modeling rogue wave dynamics, we analyze the Zeno dynamics of the Akhmediev breathers, Peregrine and Akhmediev-Peregrine soliton solutions of the nonlinear Schrodinger equation. We show that frequent measurements of the wave inhibits its movement in the observation domain for each of these solutions. We analyze the spectra of the rogue waves under Zeno dynamics. We also analyze the effect of observation frequency on the rogue wave profile and on the probability of lingering of the wave in the observation domain. Our results can find potential applications in optics including nonlinear phenomena. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.01997v2.pdf"}
{"id": "1701.02033", "abstract": "  In recent years, graphene growth optimization has been one of the key routes towards large-scale, high-quality graphene production. We have measured in-situ residual gas content during epitaxial graphene growth on silicon carbide (SiC) to find detrimental factors of epitaxial graphene growth. The growth conditions in high vacuum and purified argon are compared. The grown epitaxial graphene is studied by Raman scattering mapping and mechanical strain, charge density, number of graphene layers and graphene grain size are evaluated. Charge density and carrier mobility has been studied by Hall effect measurements in van der Pauw configuration. We have identified a major role of chemical reaction of carbon and residual water. The rate of the reaction is lowered when purified argon is used. We also show, that according to time varying gas content, it is preferable to grow graphene at higher temperatures and shorter times. Other sources of growth environment contamination are also discussed. The reaction of water and carbon is discussed to be one of the factors increasing number of defects in graphene. The importance of purified argon and its sufficient flow rate is concluded to be important for high-quality graphene growth as it reduces the rate of undesired chemical reactions and provides more stable and defined growth ambient. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.02033v1.pdf"}
{"id": "1701.02132", "abstract": "  Extended Air Showers produced by cosmic rays impinging on the earth atmosphere irradiate radio frequency radiation through different mechanisms. Upon certain conditions, the emission has a coherent nature, with the consequence that the emitted power is not proportional to the energy of the primary cosmic rays, but to the energy squared. The effect was predicted in 1962 by Askaryan and it is nowadays experimentally well established and exploited for the detection of ultra high energy cosmic rays.   In this paper we discuss in details the conditions for coherence, which in literature have been too often taken for granted, and calculate them analytically, finding a formulation which comprehends both the coherent and the incoherent emissions. We apply the result to the Cherenkov effect, obtaining the same conclusions derived by Askaryan, and to the geosynchrotron radiation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.02132v1.pdf"}
{"id": "1701.02457", "abstract": "  We study the adsorption of charged patchy particle models (CPPMs) on a thin film of a like-charged and dense polyelectrolyte (PE) brush (of 50 monomers per chain) by means of implicit-solvent, explicit-salt Langevin dynamics computer simulations. Our previously introduced set of CPPMs embraces well-defined one-, and two-patched spherical globules, each of the same net charge and (nanometer) size, with mono- and multipole moments comparable to those of small globular proteins. We focus on electrostatic effects on the adsorption far away from the isoelectric point of typical proteins, i.e., where charge regulation plays no role. Despite the same net charge of the brush and globule we observe large binding affinities up to tens of the thermal energy, kT, which are enhanced by decreasing salt concentration and increasing charge of the patch(es). Our analysis of the distance-resolved potentials of mean force together with a phenomenological description of all leading interaction contributions shows that the attraction is strongest at the brush surface, driven by multipolar, Born (self-energy), and counterion-release contributions, dominating locally over the monopolar and steric repulsions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.02457v1.pdf"}
{"id": "1701.02592", "abstract": "  Collective behaviors of populations of coupled oscillators have attracted much attention in recent years. In this paper, an order parameter approach is proposed to study the low-dimensional dynam- ical mechanism of collective synchronizations by adopting the star-topology of coupled oscillators as a prototype system. The order parameter equation of star-linked phase oscillators can be obtained in terms of the Watanabe-Strogatz transformation, Ott-Antonsen ansatz, and the ensemble order parameter approach. Different solutions of the order parameter equation correspond to diverse col- lective states, and different bifurcations reveal various transitions among these collective states. The properties of various transitions are revealed in the star-network model by using tools of nonlinear dynamics such as time reversibility analysis and linear stability analysis. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.02592v1.pdf"}
{"id": "1701.03076", "abstract": "  Numerous applications require the simultaneous redistribution of the irradiance and phase of a laser beam. The beam shape is thereby determined by the respective application. An elegant way to control the irradiance and phase at the same time is from double freeform surfaces. In this work the numerical design of continuous double freeform surfaces from ray mapping methods for collimated beam shaping with arbitrary irradiances is considered. These methods consist of the calculation of a proper ray mapping between the source and the target irradiance and the subsequent construction of the freeform surfaces. By combining the law of refraction, the constant optical path length and the surface continuity condition, a partial differential equation (PDE) for the ray mapping is derived. It is shown that the PDE can be fulfilled in a small-angle approximation by a mapping derived from optimal mass transport with a quadratic cost function. To overcome the restriction to the paraxial regime we use this mapping as an initial iterate for the simultaneous solution of the Jacobian equation and the ray mapping PDE by an optimization. The presented approach enables the efficient calculation of compact double freeform surfaces for complex target irradiances. This is demonstrated by applying it to the design of a single-lens and a two-lens system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.03076v1.pdf"}
{"id": "1701.03417", "abstract": "  Using theoretical results presented in former papers, two prototypes were developed, aiming at estimating within minutes the cost of a fibre network deployment on a given territory. The first one helps defining the limit of an urban territory and computes mathematical parameters representing its street system. The second one gives global information on a fixed network deployment on this territory, namely the probability distributions of distances and attenuation from a node of the network to the final customer, and an evaluation of the deployment cost, once given an architecture and engineering rules. This allows a final user to easily design various network architectures in the tool, to compare different deployment scenarios, and to optimize the budget and the efficiency of the network in a few minutes. The results were compared on two real French urban territories (in Tours and Rouen) to those given by an optimization tool currently used by Orange. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.03417v1.pdf"}
{"id": "1701.03568", "abstract": "  Physical-layer group secret-key (GSK) generation is an effective way of generating secret keys in wireless networks, wherein the nodes exploit inherent randomness in the wireless channels to generate group keys, which are subsequently applied to secure messages while broadcasting, relaying, and other network-level communications. While existing GSK protocols focus on securing the common source of randomness from external eavesdroppers, they assume that the legitimate nodes of the group are trusted. In this paper, we address insider attacks from the legitimate participants of the wireless network during the key generation process. Instead of addressing conspicuous attacks such as switching-off communication, injecting noise, or denying consensus on group keys, we introduce stealth attacks that can go undetected against state-of-the-art GSK schemes. We propose two forms of attacks, namely: (i) different-key attacks, wherein an insider attempts to generate different keys at different nodes, especially across nodes that are out of range so that they fail to recover group messages despite possessing the group key, and (ii) low-rate key attacks, wherein an insider alters the common source of randomness so as to reduce the key-rate. We also discuss various detection techniques, which are based on detecting anomalies and inconsistencies on the channel measurements at the legitimate nodes. Through simulations we show that GSK generation schemes are vulnerable to insider-threats, especially on topologies that cannot support additional secure links between neighbouring nodes to verify the attacks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.03568v1.pdf"}
{"id": "1701.06019", "abstract": "  Standard candles can probe the evolution of dark energy in a large redshift range. But the cosmic opacity can degrade the quality of standard candles. In this paper, we use the latest observations, including type Ia supernovae (SNe Ia) from JLA sample and Hubble parameters, to probe the opacity of the universe. In order to avoid the cosmological dependence of SNe Ia luminosity distances, a joint fitting of the SNe Ia light-curve parameters, cosmological parameters and opacity is used. In order to explore the cosmic opacity at high redshifts, the latest gamma-ray bursts (GRBs) are used. At high redshifts, cosmic reionization process is considered. We find that the sample supports an almost transparent universe for flat ΛCDM and XCDM models. Meanwhile, free electrons deplete photons from standard candles through the (inverse) Compton scattering, known as an important component of opacity. This Compton dimming may paly an important role in future supernova surveys. From analysis, we find that about a few percent cosmic opacity is caused by Compton dimming in the two models, which can be correctable. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.06019v1.pdf"}
{"id": "1701.06998", "abstract": "  We discuss the effect of an external electric field on the wetting of a solid surface by liquid. To this end, we use a model of the two-level-atom fluid for which the changes in interatomic interactions due to the presence of the field can be found using quantum-mechanical perturbation theory. Constructing the grand potential functional, we perform the standard calculations of Young's equilibrium contact angle. The switching on of the electric field |E| > 0 may increase noticeably the contact angle θ. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.06998v1.pdf"}
{"id": "1701.08641", "abstract": "  One of the most important concepts in logic and the foundations of mathematics may be useful in providing an explanation for the cosmological constant problem. A connection between self-reference and consciousness has been previously discussed due to their similar nature of making a reference to itself. Vacuum observation has the property of self-reference and consciousness in the sense that the observer is observing one's own reference frame of energy. In this paper, the cyclical loop model of self-reference is applied to the vacuum observation, such that the discrepancy between the energy density resulting from the first part of the causal loop (i.e., the classical irreversible computation of the observer's reference frame) and the other part of the causal loop (i.e., nondeterministic quantum evolution) corresponds to 10^(123). This effectively provides a consistent explanation of the difference between the observed and the theoretical values of the vacuum energy, namely, the cosmological constant problem. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.08641v3.pdf"}
{"id": "1702.00431", "abstract": "  We prove that a smooth well formed Fano weighted complete intersection of codimension 2 has a nef partition. We discuss applications of this fact to Mirror Symmetry. In particular we list all nef partitions for smooth well formed Fano weighted complete intersections of dimensions 4 and 5 and present weak Landau–Ginzburg models for them. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.00431v2.pdf"}
{"id": "1702.01984", "abstract": "  Quantum resources such as superposition and entanglement have been used to provide unconditional key distribution, secret sharing and communication complexity reduction. In this letter we present a novel quantum information protocol for dining cryptographers problem and anonymous vote casting by a group of voters. We successfully demonstrate the experimental realization of the protocol using single photon transmission. Our implementation employs a flying particle scheme where a photon passes by the voters who perform a sequence of actions (unitary transformations) on the photonic state at their local stations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.01984v1.pdf"}
{"id": "1702.02249", "abstract": "  We report that the saturation/CGC model of gluon distribution is unstable under action of the chaotic solution in a nonlinear QCD evolution equation, and it evolves to the distribution with a sharp peak at the critical momentum. We find that this gluon condensation is caused by a new kind of shadowing-antishadowing effects, and it leads to a series of unexpected effects in high energy hadron collisions including astrophysical events. For example, the extremely intense fluctuations in the transverse-momentum and rapidity distributions of the gluon jets present the gluon-jet bursts; a sudden increase of the proton-proton cross sections may fill the GZK suppression; the blocking QCD evolution will restrict the maximum available energy of the hadron-hadron colliders. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.02249v1.pdf"}
{"id": "1702.02335", "abstract": "  We have studied the ground-state properties of para-hydrogen in one dimension and in quasi-one-dimensional configurations using the path integral ground state Monte Carlo method. This method produces zero-temperature exact results for a given interaction and geometry. The quasi-one-dimensional setup has been implemented in two forms: the inner channel inside a carbon nanotube coated with H_2 and a harmonic confinement of variable strength. Our main result is the dependence of the Luttinger parameter on the density within the stable regime. Going from one dimension to quasi-one dimension, keeping the linear density constant, produces a systematic increase of the Luttinger parameter. This increase is however not enough to reach the superfluid regime and the system always remain in the quasi-crystal regime, according to Luttinger liquid theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.02335v1.pdf"}
{"id": "1702.02897", "abstract": "  Many real-world brain-computer interface (BCI) applications rely on single-trial classification of event-related potentials (ERPs) in EEG signals. However, because different subjects have different neural responses to even the same stimulus, it is very difficult to build a generic ERP classifier whose parameters fit all subjects. The classifier needs to be calibrated for each individual subject, using some labeled subject-specific data. This paper proposes both online and offline weighted adaptation regularization (wAR) algorithms to reduce this calibration effort, i.e., to minimize the amount of labeled subject-specific EEG data required in BCI calibration, and hence to increase the utility of the BCI system. We demonstrate using a visually-evoked potential oddball task and three different EEG headsets that both online and offline wAR algorithms significantly outperform several other algorithms. Moreover, through source domain selection, we can reduce their computational cost by about 50", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.02897v1.pdf"}
{"id": "1702.02922", "abstract": "  Recent localization of the repeating Fast Radio Burst (FRB) 121102 revealed the distance of its host galaxy and luminosities of the bursts. We investigated constraints on the young neutron star (NS) model, that (a) the FRB intrinsic luminosity is supported by the spin-down energy, and (b) the FRB duration is shorter than the NS rotation period. In the case of a circular cone emission geometry, conditions (a) and (b) determine the NS parameters within very small ranges, compared with that from only condition (a) discussed in previous works. Anisotropy of the pulsed emission does not affect the area of the allowed parameter region by virtue of condition (b). The determined parameters are consistent with those independently limited by the properties of the possible persistent radio counterpart and the circumburst environments such as surrounding materials. Since the NS in the allowed parameter region is older than the spin-down timescale, the hypothetical GRP-like model expects a rapid radio flux decay of ≲1 Jy within a few years as the spin-down luminosity decreases. The continuous monitoring will give a hint of discrimination of the models. If no flux evolution will be seen, we need to consider an alternative model, e.g., the magnetically powered flare. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.02922v2.pdf"}
{"id": "1702.04378", "abstract": "  We consider a layer of an inviscid fluid with free surface which is subject to vertical high-frequency vibrations. We derive three asymptotic systems of equations that describe slowly evolving (in comparison with the vibration frequency) free-surface waves. The first set of equations is obtained without assuming that the waves are long. These equations are as difficult to solve as the exact equations for irrotational water waves in a non-vibrating fluid. The other two models describe long waves. These models are obtained under two different assumptions about the amplitude of the vibration. Surprisingly, the governing equations have exactly the same form in both cases (up to interpretation of some constants). These equations reduce to the standard dispersionless shallow-water equations if the vibration is absent, and the vibration manifests itself via an additional term which makes the equations dispersive and, for small-amplitude waves, is similar to the term that would appear if surface tension were taken into account. We show that our dispersive shallow water equations have both solitary and periodic travelling waves solutions and discuss an analogy between these solutions and travelling capillary-gravity waves in a non-vibrating fluid. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.04378v1.pdf"}
{"id": "1702.05528", "abstract": "  The ability of physical layer relay caching to increase the degrees of freedom (DoF) of a single cell was recently illustrated. In this paper, we extend this result to the case of multiple cells in which a caching relay is shared among multiple non-cooperative base stations (BSs). In particular, we show that a large DoF gain can be achieved by exploiting the benefits of having a shared relay that cooperates with the BSs. We first propose a cache-assisted relaying protocol that improves the cooperation opportunity between the BSs and the relay. Next, we consider the cache content placement problem that aims to design the cache content at the relay such that the DoF gain is maximized. We propose an optimal algorithm and a near-optimal low-complexity algorithm for the cache content placement problem. Simulation results show significant improvement in the DoF gain using the proposed relay-caching protocol. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.05528v1.pdf"}
{"id": "1703.00054", "abstract": "  We investigate the impact of a fourth sterile neutrino at reactor and Spallation Neutron Source neutrino detectors. Specifically, we explore the discovery potential of the TEXONO and COHERENT experiments to subleading sterile neutrino effects through the measurement of the coherent elastic neutrino-nucleus scattering event rate. Our dedicated χ^2-sensitivity analysis employs realistic nuclear structure calculations adequate for high purity sub-keV threshold Germanium detectors. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.00054v2.pdf"}
{"id": "1703.00934", "abstract": "  At present, a large number of pulsating white dwarf (WD) stars is being discovered either from Earth-based surveys such as the Sloan Digital Sky Survey, or through observations from space (e.g., the Kepler mission). The asteroseismological techniques allow us to infer details of internal chemical stratification, the total mass, and even the stellar rotation profile. In this paper, we first describe the basic properties of WD stars and their pulsations, as well as the different sub-types of these variables known so far. Subsequently, we describe some recent findings about pulsating low-mass WDs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.00934v1.pdf"}
{"id": "1703.03019", "abstract": "  A generalized approach to Wang-Landau simulations, macroscopically constrained Wang-Landau, is proposed to simulate the density of states of a system with multiple macroscopic order parameters. The method breaks a multidimensional random-walk process in phase space into many separate, one-dimensional random-walk processes in well-defined subspaces. Each of these random walks is constrained to a different set of values of the macroscopic order parameters. When the multi-variable density of states is obtained for one set of values of field-like model parameters, the density of states for any other values of these parameters can be obtained by a simple transformation of the total system energy. All thermodynamic quantities of the system can then be rapidly calculated at any point in the phase diagram. We demonstrate how to use the multi-variable density of states to draw the phase diagram, as well as order-parameter probability distributions at specific phase points, for a model spin-crossover material: an antiferromagnetic Ising model with ferromagnetic long-range interactions. The field-like parameters in this model are an effective magnetic field and the strength of the long-range interaction. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.03019v2.pdf"}
{"id": "1703.04059", "abstract": "  Theoretical models predict that the compressed interstellar medium around runaway O stars can produce high-energy non-thermal diffuse emission, in particular, non-thermal X-ray and γ-ray emission. So far, detection of non-thermal X-ray emission was claimed for only one runaway star AE Aur. We present a search for non-thermal diffuse X-ray emission from bow shocks using archived XMM-Newton observations for a clean sample of 6 well-determined runaway O stars. We find that none of these objects present diffuse X-ray emission associated to their bow shocks, similarly to previous X-ray studies toward ζ Oph and BD+43^∘3654. We carefully investigated multi-wavelength observations of AE Aur and could not confirm previous findings of non-thermal X-rays. We conclude that so far there is no clear evidence of non-thermal extended emission in bow shocks around runaway O stars. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.04059v1.pdf"}
{"id": "1703.05400", "abstract": "  The various types of communication technologies and mobility features in Internet of Things (IoT) on the one hand enable fruitful and attractive applications, but on the other hand facilitates malware propagation, thereby raising new challenges on handling IoT-empowered malware for cyber security. Comparing with the malware propagation control scheme in traditional wireless networks where nodes can be directly repaired and secured, in IoT, compromised end devices are difficult to be patched. Alternatively, blocking malware via patching intermediate nodes turns out to be a more feasible and practical solution. Specifically, patching intermediate nodes can effectively prevent the proliferation of malware propagation by securing infrastructure links and limiting malware propagation to local device-to-device dissemination. This article proposes a novel traffic-aware patching scheme to select important intermediate nodes to patch, which applies to the IoT system with limited patching resources and response time constraint. Experiments on real-world trace datasets in IoT networks are conducted to demonstrate the advantage of the proposed traffic-aware patching scheme in alleviating malware propagation. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.05400v1.pdf"}
{"id": "1703.05444", "abstract": "  This paper studies a recently proposed continuous-time distributed self-appraisal model with time-varying interactions among a network of n individuals which are characterized by a sequence of time-varying relative interaction matrices. The model describes the evolution of the social-confidence levels of the individuals via a reflected appraisal mechanism in real time. We first show by example that when the relative interaction matrices are stochastic (not doubly stochastic), the social-confidence levels of the individuals may not converge to a steady state. We then show that when the relative interaction matrices are doubly stochastic, the n individuals' self-confidence levels will all converge to 1/n, which indicates a democratic state, exponentially fast under appropriate assumptions, and provide an explicit expression of the convergence rate. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.05444v1.pdf"}
{"id": "1703.07067", "abstract": "  In this paper, we investigate and develop a new approach to the numerical analysis and characterization of random fluctuations with heavy-tailed probability distribution function (PDF), such as turbulent heat flow and solar flare fluctuations. We identify the heavy-tailed random fluctuations based on the scaling properties of the tail exponent of the PDF, power-law growth of qth order correlation function and the self-similar properties of the contour lines in two-dimensional random fields. Moreover, this work leads to a substitution for fractional Edwards-Wilkinson (EW) equation that works in presence of μ-stable Lévy noise. Our proposed model explains the configuration dynamics of the systems with heavy-tailed correlated random fluctuations. We also present an alternative solution to the fractional EW equation in the presence of μ-stable Lévy noise in the steady-state, which is implemented numerically, using the μ-stable fractional Lévy motion. Based on the analysis of the self-similar properties of contour loops, we numerically show that the scaling properties of contour loop ensembles can qualitatively and quantitatively distinguish non-Gaussian random fields from Gaussian random fluctuations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.07067v1.pdf"}
{"id": "1703.07799", "abstract": "  We address the physical nature of subdwarf A-type (sdA) stars and their possible link to extremely low mass (ELM) white dwarfs (WDs). The two classes of objects are confused in low-resolution spectroscopy. However, colors and proper motions indicate that sdA stars are cooler and more luminous, and thus larger in radius, than published ELM WDs. We demonstrate that surface gravities derived from pure hydrogen models suffer a systematic  1 dex error for sdA stars, likely explained by metal line blanketing below 9000 K. A detailed study of five eclipsing binaries with radial velocity orbital solutions and infrared excess establishes that these sdA stars are metal-poor  1.2 Msun main sequence stars with  0.8 Msun companions. While WDs must exist at sdA temperatures, only  1", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.07799v1.pdf"}
{"id": "1703.09282", "abstract": "  There are many cluster analysis methods that can produce quite different clusterings on the same dataset. Cluster validation is about the evaluation of the quality of a clustering; \"relative cluster validation\" is about using such criteria to compare clusterings. This can be used to select one of a set of clusterings from different methods, or from the same method ran with different parameters such as different numbers of clusters.   There are many cluster validation indexes in the literature. Most of them attempt to measure the overall quality of a clustering by a single number, but this can be inappropriate. There are various different characteristics of a clustering that can be relevant in practice, depending on the aim of clustering, such as low within-cluster distances and high between-cluster separation.   In this paper, a number of validation criteria will be introduced that refer to different desirable characteristics of a clustering, and that characterise a clustering in a multidimensional way. In specific applications the user may be interested in some of these criteria rather than others. A focus of the paper is on methodology to standardise the different characteristics so that users can aggregate them in a suitable way specifying weights for the various criteria that are relevant in the clustering application at hand. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.09282v2.pdf"}
{"id": "adap-org9910001", "abstract": "  This is a brief introduction to fractals, multifractals and wavelets in an accessible way, in order that the founding ideas of those strange and intriguing newcomers to science as fractals may be communicated to a wider public. Fractals are the geometry of the wildness of nature, where the euclidian geometry fails. The structures of nonlinear dynamics associated with chaos are fractal. Fractals may also be used as the geometry of social systems.   Wavelets are introduced as a tool for fractal analysis. As an example of its application on a social system, we use wavelet fractal analysis to compare electrical power demand of two different places, a touristic city and a whole country. ", "pdf_url": "gs://arxiv-dataset/arxiv/adap-org/pdf/9910/9910001v1.pdf"}
{"id": "astro-ph0001146", "abstract": "  There is an effect in the modified dynamics (MOND) that is conducive to formation of warps. Because of the nonlinearity of the theory the internal dynamics of a galaxy is affected by a perturber over and above possible tidal effects. For example, a relatively distant and light companion or the mean influence of a parent cluster, with negligible tidal effects, could still produce a significant warp in the outer part of a galactic disk. We present results of numerical calculations for simplified models that show, for instance, that a satellite with the (baryonic) mass and distance of the Magellanic clouds can distort the axisymmetric field of the Milky Way enough to produce a warp of the magnitude (and position) observed. Details of the warp geometry remain to be explained: we use a static configuration that can produce only warps with a straight line of nodes. In more realistic simulations one must reckon with the motion of the perturbing body, which sometimes occurs on time scales not much longer than the response time of the disk. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0001/0001146v1.pdf"}
{"id": "astro-ph0001287", "abstract": "  We have proposed in a companion paper (Considere et al. 2000) that bars appeared recently in massive starburst nucleus galaxies. We now test this hypothesis on an extended sample of barred and unbarred Markarian starburst galaxies, using several samples of normal galaxies as control samples.   In support of this hypothesis, we show that the proportion of barred galaxies is much lower in Markarian starburst galaxies than in normal galaxies. In addition to this deficiency of bars, we find that Markarian starburst galaxies have smaller disks than normal galaxies, and that the disks of unbarred starburst galaxies are smaller, on average, than barred ones. Finally, we show that the Markarian starburst galaxies do not seem to follow the local Tully–Fisher relation.   Various alternatives are examined to explain the deficiency of bars and the small disk dimensions in Markarian starburst galaxies. One possibility, which is in agreement with the young bar hypothesis, is that the formation of disks happens after the formation of bulges and that bars appear only later, when enough gas has been accreted in the disk. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0001/0001287v1.pdf"}
{"id": "astro-ph0002052", "abstract": "  We analyze the properties of the pulsed emission from the accreting millisecond pulsar SAX J1808.4-3658 in observations of its April 1998 outburst by the Rossi X-Ray Timing Explorer. Pulse phase spectroscopy shows that the emission evolves from a hard spectrum (power law with photon index 2.39+-0.06) to a soft spectrum (index 3.39+-0.24). This softening is also observable as a phase lag in the fundamental of low-energy photons with respect to high-energy photons. We show that this lag is roughly constant over ten days of the outburst. We fit these data with a model where the pulse emission is from a hot spot on the rotating neutron star and the flux as a function of phase is calculated including the effects of general relativity. The energy-dependent lags are very well described by this model. The harder spectra at earlier phases (as the spot approaches) are the result of larger Doppler boosting factors which are important for this fast pulsar. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0002/0002052v1.pdf"}
{"id": "astro-ph0002181", "abstract": "  We present statistics of SGR 1806-20 bursts, combining 290 events detected with RXTE/PCA, 111 events detected with BATSE and 134 events detected with ICE. We find that the fluence distribution of bursts observed with each instrument are well described by power laws with indices 1.43, 1.76 and 1.67, respectively. The distribution of time intervals between successive bursts from SGR 1806-20 is described by a lognormal function with a peak at 103 s. There is no correlation between the burst intensity and either the waiting times till the next burst or the time elapsed since the previous burst. In all these statistical properties, SGR 1806-20 bursts resemble a self-organized critical system, similar to earthquakes and solar flares. Our results thus support the hypothesis that the energy source for SGR bursts is crustquakes due to the evolving, strong magnetic field of the neutron star, rather than any accretion or nuclear power. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0002/0002181v1.pdf"}
{"id": "astro-ph0002452", "abstract": "  Previously we have shown (Maller et al, 1998) that the kinematics of Damped Lyman Alpha Systems (DLAS) as measured by Prochaska and Wolfe (1998) can be reproduced in a multiple disk model (MDM) if the gaseous disks are of sufficient radial extent. Here we discuss this model's predictions for the relationship between DLAS and Lyman break galaxies (LBGs), which we here take to be objects at z 3 brighter than R=25.5. We expect that future observations of the correlations between DLAS and LBGs will provide a new data set able to discriminate between different theoretical models of the DLAS. Djorgovski (1997) has already detected a few optical counterparts and more studies are underway. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0002/0002452v1.pdf"}
{"id": "astro-ph0003460", "abstract": "  We report the results of a long-term campaign of radio, soft- and hard- X-ray observations of the galactic black hole candidate GX 339-4. In the Low-Hard X-ray state the system displays a strong 3-way linear correlation between soft- and hard-X-rays and radio emission, implying a coupling between the Comptonising corona and a radio-emitting compact jet. In this state the radio emission is linearly polarised at a level of around 2 ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0003/0003460v1.pdf"}
{"id": "astro-ph0004240", "abstract": "  We show that main-sequence stars in dense stellar cusps around massive black holes are likely to rotate at a significant fraction of the centrifugal breakup velocity due to spin-up by hyperbolic tidal encounters. We use realistic stellar structure models to calculate analytically the tidal spin-up in soft encounters, and extrapolate these results to close and penetrating collisions using smoothed particle hydrodynamics simulations. We find that the spin-up falls off only slowly with distance from the black hole because the increased tidal coupling in slower collisions at larger distances compensates for the decrease in the stellar density. We apply our results to the stars near the massive black hole in the Galactic Center. Over their lifetime,  1 Msol main sequence stars in the inner 0.3 pc of the Galactic Center are spun-up on average to  10", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0004/0004240v1.pdf"}
{"id": "astro-ph0004331", "abstract": "  We study the perturbation modes of rotating superfluid ellipsoidal figures of equilibrium in the framework of the two-fluid superfluid hydrodynamics and Newtonian gravity. Our calculations focus on linear perturbations of background equilibria in which the two fluids move together, the total density is uniform, and the densities of the two components are proportional to one another, with ratios that are independent of position. The motions of the two fluids are coupled by mutual friction, as formulated by Khalatnikov. We show that there are two general classes of modes for small perturbations: one class in which the two fluids move together and the other in which there is relative motion between them. The former are identical to the modes found for a single fluid, except that the rate of viscous dissipation, when computed in the secular (or “low Reynolds number”) approximation under the assumption of a constant kinematic viscosity, is diminished by a factor f_N, the fraction of the total mass in the normal fluid. The relative modes are completely new, and are studied in detail for a range of values for the phenomenological mutual friction coefficients, relative densities of the superfluid and normal components, and, for Roche ellipsoids, binary mass ratios. We find that there are no new secular instabilities connected with the relative motions of the two fluid components. Moreover, although the new modes are subject to viscous dissipation (a consequence of viscosity of the normal matter), they do not emit gravitational radiation at all. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0004/0004331v2.pdf"}
{"id": "astro-ph0005152", "abstract": "  Broad infrared spectra (7-200 micrometer) of four NLS1 galaxies, obtained with the imaging photo-polarimeter (ISOPHOT) on board the Infrared Space Observatory (ISO), are presented. The infrared luminosities and temperatures, opacities and sizes of the emitting dust components are derived. A comparison between the observed infrared spectra and the optical emission line fluxes of a sample of 16 NLS1 galaxies suggests that these objects suffer different degrees of dust absorption according to the inclination of the line of sight with respect to the dust distribution. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0005/0005152v1.pdf"}
{"id": "astro-ph0005554", "abstract": "  The Cosmic Background due to the integrated radiation from galaxies over the whole life of the Universe is reviewed. We find that this background is well constrained by measurements. The total power in the background is in the range 60-93 nW/m2/sr. The data show the existence of a minimum separating the direct stellar radiation from the infrared part due to radiation reemitted by dust. This reemitted dust radiation is about 1-2.6 time the background power in the optical/near-IR thus much larger than the same ratio measured locally (30", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0005/0005554v2.pdf"}
{"id": "astro-ph0006027", "abstract": "  Following Waxman and Bahcall we calculate the event rate, energy and zenith angle dependence of neutrinos produced in the fireball model of gamma ray bursts (GRB). We emphasize the primary importance of i) burst-to-burst fluctuations and ii) absorption of the neutrinos in the Earth. From the astronomical point of view, we draw attention to the sensitivity of neutrino measurements to the boost Lorentz factor of the fireball Γ, which is central to the fireball model, and only indirectly determined by follow-up observations. Fluctuations result in single bursts emitting multiple neutrinos, making it possible to determine the flavor composition of a beam observed after a baseline of thousands of Megaparsecs. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0006/0006027v2.pdf"}
{"id": "astro-ph0007072", "abstract": "  We report first results of an implementation of a chemical model in a cosmological code, based on the Smoothed Particle Hydrodynamics (SPH) technique. We show that chemical SPH simulations are a promising tool to provide clues for the understanding of the chemical properties of galaxies in relation to their formation and evolution in a cosmological framework. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0007/0007072v1.pdf"}
{"id": "astro-ph0007121", "abstract": "  We discuss a comparison of models for the formation of disk galaxies both in a Universe dominated by cold dark matter (CDM) and one in which the force law is given by modified Newtonian dynamics (MOND). Our main aim is to address the claim made by McGaugh     de Blok that CDM suffers from severe fine-tuning problems, which are circumvented under MOND. As we show, CDM indeed requires some amount of tuning of the feedback efficiencies to obtain a Tully-Fisher relation (TFR) as steep as observed. However, that same model is in excellent agreement with a wide variety of additional observations. Therefore, the modest amount of feedback needed should not be regarded a fine-tuning problem. Instead, its requirement should be considered a generic prediction for CDM, which might be tested with future observations and with detailed modeling of feedback processes. We also show that galaxy formation in a MOND universe can not simultaneously reproduce the TFR and the lack of high surface brightness dwarf galaxies. We thus conclude that CDM is a more viable theory for the formation of disk galaxies than MOND. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0007/0007121v1.pdf"}
{"id": "astro-ph0008078", "abstract": "  We search for signatures of planets in 43 intensively monitored microlensing events that were observed between 1995 and 1999. Planets would be expected to cause a short duration ( 1 day) deviation on the smooth, symmetric light curve produced by a single-lens. We find no such anomalies and infer that less than 1/3 of the  0.3 M_sun stars that typically comprise the lens population have Jupiter-mass companions with semi-major axes in the range of 1.5 AU <a < 4 AU. Since orbital periods of planets at these radii are 3-15 years, the outer portion of this region is currently difficult to probe with any other technique. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0008/0008078v2.pdf"}
{"id": "astro-ph0008113", "abstract": "  There is compelling evidence that at least some clusters of galaxies are powerful sources of non-thermal radiation. In all cases where this radiation has been detected, a general trend is that high energy densities of cosmic rays and correspondingly low values of the average magnetic field are required in order to have a self-consistent picture of the multiwavelength observations. Mergers of clusters of galaxies might provide large enough cosmic ray injection rates and at the same time provide the mechanism for the heating of the intracluster medium to the observed temperatures. In this paper we analyze critically all the components that play a role in the non-thermal emission of clusters during a merger, with special attention to mergers occurred in the past of the cluster. We outline the consequences of this model for high energy gamma ray observations and for Faraday rotation measurements of the intracluster magnetic field. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0008/0008113v1.pdf"}
{"id": "astro-ph0008203", "abstract": "  We compare accretion shock models with optical and ultraviolet spectra of pre-main sequence stars to (1) make the first determinations of accretion rates in intermediate mass T Tauri stars from continuum emission, and (2) derive improved estimates of accretion rates and extinctions for continuum T Tauri stars. Our method extends the shock models developed by Calvet and Gullbring to enable comparisons with optical and archival International Ultraviolet Explorer ultraviolet spectra. We find good agreement between the observations and the model predictions, supporting the basic model of magnetospheric accretion shocks as well as previous determinations of accretion rates and interstellar reddening for the low mass T Tauri stars. The accretion rates determined for the intermediate-mass T Tauri stars agree well with values obtained through other methods that use near-infrared hydrogen line strengths (Muzerolle et al. 1998). ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0008/0008203v1.pdf"}
{"id": "astro-ph0008342", "abstract": "  New images of 7 radio halos and relics, obtained with the Very Large Array at 20 or 90 cm, are presented here. The existence of a cluster-wide radio halo in the clusters A 665 and CL 0016+16 is confirmed. Both these clusters share the properties of the other clusters with radio halos, i.e. are luminous in X-rays, have high temperature, and show recent merger processes. No diffuse sources are detected in a sample of clusters showing at least a tailed radio galaxy within 300 kpc from the cluster center, indicating that the connection between tailed radio galaxies and halos is not relevant. For these clusters we give limits to the surface brightness and to the angular size of possible undetected diffuse sources. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0008/0008342v1.pdf"}
{"id": "astro-ph0008514", "abstract": "  We discuss the transport of angular momentum induced by tidal effects in a disk surrounding a star in a pre-main sequence binary system. We consider the effect of both density and bending waves. Although tidal effects are important for truncating protostellar disks and for determining their size, it is unlikely that tidally-induced angular momentum transport plays a dominant role in the evolution of protostellar disks. Where the disk is magnetized, transport of angular momentum is probably governed by MHD turbulence. In a non self-gravitating laminar disk, the amount of transport provided by tidal waves is probably too small to account for the lifetime of protostellar disks. In addition, tidal effects tend to be localized in the disk outer regions. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0008/0008514v1.pdf"}
{"id": "astro-ph0009478", "abstract": "  The Faint Sky Variability Survey is aimed at finding variable objects in the brightness range between 17th and 25th magnitude on timescales between tens of minutes and years with photometric precisions ranging from 3 millimagnitudes for the brightest to 0.2 magnitudes for the faintest objects. An area of at least 50 square degrees, located at mid-galactic latitudes, will be covered using the Wide Field Camera on the 2.5m Isaac Newton Telescope on La Palma. The survey started in November 1998 as part of the INT Wide Field Survey program. Here we describe the main goals of the Faint Sky Variability Survey, the methods used in extracting the relevant information and the future prospects of the survey. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0009/0009478v1.pdf"}
{"id": "astro-ph0010363", "abstract": "  We have made high-resolution, high-sensitivity dynamic spectra of a sample of strong pulsars at 430 MHz with the Arecibo radiotelescope. For 4 pulsars we find faint but sharply delineated features in the secondary spectra. These are examples of the previously observed “crisscross” or “multiple drift slope” phenomenon presumed to be due to multiple imaging of the pulsar by the interstellar medium. The unprecedented resolution and dynamic range of our observations allow a deeper level of analysis. Distances to the dominant scattering screen along the line of sight are determined and are shown to agree well with those inferred from other scintillation phenomena. Multiple imaging of the pulsar by the ISM is required. A compact central image surrounded by a faint scattering halo, roughly circularly symmetric, is consistent with the data. Scattering from filaments may also be consistent. The angular extent of the scattering material parallel to the direction of the pulsar velocity is roughly 5 mas, corresponding to a linear extent of about 2 AU. Further observations of these features should allow better discrimination between models and an identification of the scattering structures. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0010/0010363v2.pdf"}
{"id": "astro-ph0010460", "abstract": "  The far infrared background is a sink for the hidden aspects of galaxy formation. At optical wavelengths, ellipticals and spheroids are old, even at z ∼ 1. Neither the luminous formation phase nor their early evolution is seen in the visible. We infer that ellipticals and, more generally, most spheroids must have formed in dust-shrouded starbursts. In this article, we show how separate tracking of disk and spheroid star formation enables us to infer that disks dominate near the peak in the cosmic star formation rate at z  2 and in the diffuse ultraviolet/optical/infrared background, whereas spheroid formation dominates the submillimetre background. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0010/0010460v1.pdf"}
{"id": "astro-ph0011301", "abstract": "  We calculate the energy distribution of the relativistic particles injected in the ICM during a phase of reacceleration of the relativistic particles in the cluster volume. We apply our results to the case of the Coma cluster in which recent merging activity and the presence of the radio halo may suggest that reacceleration processes are efficient. We find that the electron population injected in the central part of the cluster by the head-tail radio galaxy NGC 4869 may account for a large fraction, if not all, of the detected EUV excess via inverse Compton scattering of the cosmic microwave background (CMB) photons. If radio haloes are powered by reacceleration mechanisms active in the cluster volume, moderate non-thermal EUV excesses (of order of ∼ 1-5 · 10^42erg s^-1) should be a common feature of clusters containing powerful head-tail radio galaxies and/or AGNs. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0011/0011301v1.pdf"}
{"id": "astro-ph0011551", "abstract": "  We consider envelopes of DB white dwarfs which are not composed of pure 4-He, but rather a mixture of 3-He and 4-He. Given this assumption, the same diffusive processes which produce a relatively pure H layer overlying a He layer in the DA's should work to produce a 3-He layer overlying a 4-He layer in the DB's. We examine the relevant timescales for diffusion in these objects, and compare them to the relevant evolutionary timescales in the context of the DBV white dwarfs. We then explore the consequences which 3-He separation has on the pulsational spectra of DBV models. Since GD 358 is the best-studied member of this class of variables, we examine fits to its observed pulsation spectrum. We find that the inclusion of a 3-He layer results in a modest improvement in a direct fit to the periods, while a fit to the period spacings is significantly improved. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0011/0011551v1.pdf"}
{"id": "astro-ph0101039", "abstract": "  High-energy gamma rays are a valuable tool for studying particle acceleration and radiation in the magnetospheres of energetic pulsars. The six or more pulsars seen by CGRO/EGRET show that: the light curves usually have double-peak structures (suggesting a broad cone of emission); gamma rays are frequently the dominant component of the radiated power; and all the spectra show evidence of a high-energy turnover. Unless a new pulsed component appears at higher energies, progress in gamma-ray pulsar studies will be greatest in the 1-20 GeV range. Ground-based telescopes whose energy ranges extend downward toward 10 GeV should make important measurements of the spectral cutoffs. The Gamma-ray Large Area Space Telescope (GLAST), now in planning for a launch in 2005, will provide a major advance in sensitivity, energy range, and sky coverage. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0101/0101039v1.pdf"}
{"id": "astro-ph0101042", "abstract": "  The secular instability and nonlinear evolution of the m=2 f-mode (bar-mode) driven by gravitational radiation reaction in a rapidly rotating, newly formed neutron star are reviewed. There are two types of rotating bars which generate quite different gravitational waveforms: those with large internal rotation relative to the bar figure (Dedekind-like bars) have GW frequency sweeping downward during the evolution, and those with small internal rotation (Jacobi-like) have GW frequency sweeping upward. Various sources of viscosity (which affects the instability) in hot nuclear matter are reexamined, and the possible effect of star-disk coupling on the bar-mode instability is also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0101/0101042v1.pdf"}
{"id": "astro-ph0101191", "abstract": "  It is often stated that homogeneity and isotropy of the Universe are assumptions of the almost Friedmann-Lema^itre (FL) model (the hot big bang model), inspired from the Copernican Principle. However, only local homogeneity and isotropy are required by the model: multiply connected almost FL models are locally homogeneous and isotropic, but they can be globally anisotropic and/or globally inhomogeneous. Toy models are used here to show how global anisotropy and/or global inhomogeneity of an almost FL model could be shown directly in observations. This approach may avoid having to make any assumptions regarding global anisotropy and inhomogeneity. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0101/0101191v1.pdf"}
{"id": "astro-ph0101449", "abstract": "  We propose a new method for extracting the non-Gaussian signatures on the isotemperature statistics in the cosmic microwave background (CMB) sky, which is induced by the gravitational lensing due to the intervening large-scale structure of the universe. To develop the method, we focus on a specific statistical property of the intrinsic Gaussian CMB field; a field point in the map that has a larger absolute value of the temperature threshold tends to have a larger absolute value of the curvature parameter defined by a trace of second derivative matrix of the temperature field, while the ellipticity parameter similarly defined is uniformly distributed independently of the threshold because of the isotropic nature of the Gaussian field. The weak lensing then causes a stronger distortion effect on the isotemperature contours with higher threshold and especially induces a coherent distribution of the ellipticity parameter correlated with the threshold as a result of the coupling between the CMB curvature parameter and the gravitational tidal shear in the observed map. These characteristic patterns can be statistically picked up by considering three independent characteristic functions, which are obtained from the averages of quadratic combinations of the second derivative fields of CMB over isotemperature contours with each threshold. Consequently, we find that the lensing effect generates non-Gaussian signatures on those functions that have a distinct functional dependence of the threshold. We test the method using numerical simulations of CMB maps and show that the lensing signals can be measured definitely, provided that we use CMB data with sufficiently low noise and high angular resolution. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0101/0101449v2.pdf"}
{"id": "astro-ph0102132", "abstract": "  The start of operation of several large-aperture telescopes has motivated several groups around the world to conduct deep large imaging surveys, complementing other wide-area but shallower surveys. A special class of imaging surveys are the public ones such as those being conducted by the ESO Imaging Survey (EIS) project established with the primary objective of providing to the ESO community large datasets from which samples can be drawn for VLT programs. To date several surveys have been carried out providing multi-passband optical data over relatively large areas to moderate depth, deep optical/infrared surveys of smaller fields as well as observations of a large number of selected stellar fields. These surveys have produced a large amount of well-defined datasets with known limits from which a variety of data products have been extracted and distributed. The goal of the present contribution is to give an overview of the EIS project, to present the end-to-end survey system being developed by this program and to highlight the effort being made to standardize procedures, to build software tools to assess the quality of the derived products and to explore the available datasets in a systematic and consistent way to search for astronomical objects of potential scientific interest. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0102/0102132v1.pdf"}
{"id": "astro-ph0103061", "abstract": "  For the past twenty-five years, nearly all analyses of accretion disk dynamics have assumed that stress inside the disk is locally proportional to pressure (the \"alpha-model\") and that this stress goes to zero at the marginally stable orbit. Recently, it has been demonstrated that MHD turbulence accounts for the bulk of internal disk stress. In contradiction with the traditional view, the stress from this MHD turbulence does not diminish near the marginally stable orbit, and the ratio of magnetic stress to pressure rises sharply there. Examples of the consequences include: an increase in accretion efficiency that may also be time- and circumstance-dependent; a decrease in the rate of black hole spin-up by accretion; and generation of disk luminosity fluctuations. Preliminary results from numerical simulations lend support to analytic estimates of these effects. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0103/0103061v1.pdf"}
{"id": "astro-ph0103164", "abstract": "  We present results on variation in rotation rate in the upper convection zone using data from GONG and MDI/SOHO covering a period of more than four years. We find that the first few odd-order splitting coefficients vary systematically with the solar cycle. The rotation rate near the solar surface calculated from analytical methods agrees well with that of inversion techniques. The residual rotation rate in the outer layers seem to be correlated with the solar activity. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0103/0103164v1.pdf"}
{"id": "astro-ph0103496", "abstract": "  Symbiotic stars are long-period interacting binary systems in which an evolved red giant star transfers material to its much hotter compact companion. Such a composition places them among the most variable stars. In addition to periodic variations due to the binary motion they often show irregular changes due to nova-like eruptions of the hot component. In some systems the cool giant is a pulsating Mira-type star usually surrounded by a variable dust shell. Here, I present results of optical and IR monitoring of symbiotic systems as well as future prospects for such studies. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0103/0103496v1.pdf"}
{"id": "astro-ph0104078", "abstract": "  Quantum field theory at finite temperature and density can be used for describing the physics of relativistic plasmas. Such systems are frequently encountered in astrophysical situations, such as the early Universe, Supernova explosions, and the interior of neutron stars. After a brief introduction to thermal field theory the usefulness of this approach in astrophysics will be exemplified in three different cases. First the interaction of neutrinos within a Supernova plasma will be discussed. Then the possible presence of quark matter in a neutron star core and finally the interaction of light with the Cosmic Microwave Background will be considered. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0104/0104078v2.pdf"}
{"id": "astro-ph0104287", "abstract": "  Neutron stars may be surrounded by fall-back disks formed from supernova core-collapse. If the disk circumscribes the light-cylinder, the neutron star will be an active radio pulsar spinning down under the propeller spin-down torque applied by the disk as well as the usual magnetic dipole radiation torque. Evolution across the P-P_dot diagram is very rapid when pulsar spin-down is dominated by the propeller torque. This explains the distribution of pulsars in the P-P_dot diagram. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0104/0104287v3.pdf"}
{"id": "astro-ph0105003", "abstract": "  I suggest that radio-wave scattering by the interstellar plasma, in combination with subsonic gradients in the Doppler velocity of interstellar HI, is responsible for the observed small-scale variation in HI absorption spectra of pulsars. Velocity gradients on the order of 0.05 to 0.3 km/s across 1 AU can produce the observed variations. I suggest observational tests to distinguish between this model and the traditional picture of small-scale opacity variations from cloudlets. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0105/0105003v1.pdf"}
{"id": "astro-ph0105469", "abstract": "  Detached eclipsing binary stars provide a robust one-step distance determination to nearby galaxies. As a by-product of Galactic microlensing searches, catalogs of thousands of variable stars including eclipsing binaries have been produced by the OGLE, MACHO and EROS collaborations. We present photometric solutions for detached eclipsing binaries in the Small Magellanic Cloud (SMC) discovered by the OGLE collaboration. The solutions were obtained with an automated version of the Wilson-Devinney program. By fitting mock catalogs of eclipsing binaries we find that the normalized stellar radii (particularly their sum) and the surface brightness ratio are accurately described by the fitted parameters and estimated standard errors, despite various systematic uncertainties. In many cases these parameters are well constrained. In addition we find that systems exhibiting complete eclipses can be reliably identified where the fractional standard errors in the radii are small. We present two quantitatively selected sub-samples of eclipsing binaries that will be excellent distance indicators. These can be used both for computation of the distance to the SMC and to probe its structure. One particularly interesting binary has a very well determined solution, exhibits complete eclipses, and is comprised of well detached G-type, class II giants. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0105/0105469v1.pdf"}
{"id": "astro-ph0105495", "abstract": "  Star forming galaxies exhibit a variety of physical conditions, from quiescent normal spirals to the most powerful dusty starbursts. In order to study these complex systems, we need a suitable tool to analyze the information coming from observations at all wavelengths. We present a new spectro-photometric model which considers in a consistent way starlight as reprocessed by gas and dust. We discuss preliminary results to interpret some observed properties of VLIRGs. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0105/0105495v1.pdf"}
{"id": "astro-ph0106157", "abstract": "  Positron annihilation radiation from the Galaxy has been observed by the OSSE, SMM and TGRS instruments. Improved spectral modeling of OSSE observations has allowed studies of the distribution of both positron annihilation radiation components, the narrow line emission at 511 keV and the positronium continuum emission. The results derived for each individual annihilation component are then compared with each other. These comparisons reveal approximate agreement between the distribution of these two emissions. In certain regions of the sky (notably in the vicinity of the previously reported positive latitude enhancement), the distribution of the emissions differ. We discuss these differences and the methods currently being employed to understand whether the differences are physical or a systematic error in the present analysis. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0106/0106157v1.pdf"}
{"id": "astro-ph0106227", "abstract": "  I suggest that the bulk of the \"young\", second-parameter globular clusters (SPGCs) observed in the outer halo of our Galaxy and recently found in other massive spiral of the Local Group (LG), M33, may have originated due to mass outflow from M31 and subsequent accretion of gas on the Galaxy and M33 in the early epoch. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0106/0106227v1.pdf"}
{"id": "astro-ph0107561", "abstract": "  In this paper we present some results of numerical simulations concerning the development of galactic winds in starburst galaxies. In particular, we focus on a galaxy similar to IZw18, the most metal-poor galaxy locally known. We compute the chemio-dynamical evolution of this galaxy, considering the energetic input and the chemical yields originating from Supernovae (SNe) of Type II and Ia and from intermediate-mass stars. We consider both single, instantaneous starburst and two starbursts separated by a quiescent period. In all considered cases a metal enriched winds develops and in particular the metals produced by Type Ia SNe are ejected more efficiently than the other metals. We suggest that two burst of star formation, the first being weaker and the last having an age of some tenth of Myr, can satisfactorily reproduce the abundances and abundance ratios found in literature for IZw18 ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0107/0107561v1.pdf"}
{"id": "astro-ph0109050", "abstract": "  We present a new technique for determining an upper limit for the mass of the black hole in active galactic nuclei showing warm absorption features. The method relies on the balance of radiative and gravitational forces acting on outflowing warm absorber clouds. It has been applied to 6 objects: five Seyfert 1 galaxies: IC 4329a, MCG-6-30-15, NGC 3516, NGC 4051 and NGC 5548; and one radio-quiet quasar: MR 2251-178. We discuss our result in comparison with other methods. The procedure could also be applied to any other radiatively driven optically thin outflow in which the spectral band covering the major absorption is directly observed. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0109/0109050v1.pdf"}
{"id": "astro-ph0109163", "abstract": "  We have developed a geometrical method based on 3D Voronoi polyhedra and Delaunay tessellation for identifying and reconstructing clusters of galaxies in the next generation of deep, flux-limited redshift surveys. We here describe this algorithm and tests of it using mock catalogs that simulate the DEEP2/DEIMOS redshift survey, which will begin observations in the Spring of 2002 and will provide a detailed three dimensional map of the large scale structure up to redshift 1.5. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0109/0109163v1.pdf"}
{"id": "astro-ph0110665", "abstract": "  We present our catalog of U, B, V, and I stellar photometry of the central 18 sq. degree area of the Small Magellanic Cloud. We combine our data with the 2MASS and DENIS catalogs to provide, when available, U through K_S data for stars. Internal and external astrometric and photometric tests using existing optical photometry (U, B, and V from Massey's bright star catalog; B, V, and I from the microlensing database of OGLE and I from the near-infrared sky survey DENIS) are used to determine the observational uncertainties and identify systematic errors. We fit stellar atmosphere models to the optical data to check the consistency of the photometry for individual stars across the passbands and to estimate the line-of-sight extinction. Finally, we use the estimated line-of-sight extinctions to produce an extinction map across the Small Magellanic Cloud and investigate the nature of extinction as a function of stellar population. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0110/0110665v1.pdf"}
{"id": "astro-ph0111100", "abstract": "  In this survey we have systematically mapped 63 cloud cores in the CS J = 5 -> 4 line towards a sample of high mass star forming cores with water masers (Plume et al. 1992, Plume et al. 1997) using the CSO. From the CS spectra and maps we determine cloud core sizes, virial masses, a mass spectrum, and a size-linewidth relationship. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0111/0111100v1.pdf"}
{"id": "astro-ph0111405", "abstract": "  The association of G343.1-2.3 and PSR 1706-44 has been controversial from its first proposal. In this paper we present new evidence from images made by with the Australia Telescope Compact Array (ATCA), MRT and Mt. Pleasant. To cover the full extent of G343.1-2.3 with ATCA mosaicing was required, and we present the polarisation images from this experiment. The ATCA observations confirms the much larger extent of the SNR, which now encompasses the pulsar. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0111/0111405v1.pdf"}
{"id": "astro-ph0112479", "abstract": "  We have searched for nonastrophysical emission lines in the optical spectra of 577 nearby F, G, K, and M main-sequence stars. Emission lines of astrophysical origin would also have been detected, such as from a time–variable chromosphere or infalling comets. We examined  20 spectra per star obtained during four years with the Keck/HIRES spectrometer at a resolution of 5 km/s, with a detection threshold 3", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0112/0112479v2.pdf"}
{"id": "astro-ph0201452", "abstract": "  We review the progress of research on intracluster planetary nebulae (IPN). In the past five years, hundreds of IPN candidates have been detected in the Virgo and Fornax galaxy clusters and searches are also underway in poorer galaxy groups. From the observations to date, and applying the known properties of extragalactic planetary nebulae, the intracluster light in Virgo and Fornax: 1) is significant, at least 20", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0201/0201452v1.pdf"}
{"id": "astro-ph0202273", "abstract": "  The presence of planets around solar-type stars suggests that many white dwarfs should have relic planetary systems. While planets closer than ∼ 5 AU will most likely not survive the post-main sequence lifetime of its parent star, any planet with semimajor axis > 5 AU will survive, and its semimajor axis will increase as the central star loses mass. Since the stability of adjacent orbits to mutual planet-planet perturbations depends on the ratio of the planet mass to the central star's mass, some planets in previously stable orbits around a star undergoing mass loss will become unstable. We show that when mass loss is slow, systems of two planets that are marginally stable can become unstable to close encounters, while for three planets the timescale for close approaches decreases significantly with increasing mass ratio. These processes could explain the presence of anomalous IR excesses around white dwarfs that cannot be explained by close companions, such as G29-38, and may also be an important factor in explaining the existence of DAZ white dwarfs. The onset of instability through changing mass-ratios will also be a significant effect for planetary embryos gaining mass in protoplanetary disks. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0202/0202273v1.pdf"}
{"id": "astro-ph0202413", "abstract": "  We present the results of the deep NIR imaging observations using the Subaru telescope. At the Hubble Deep Field North, we obtained the new and deepest K'-band image (10 hours) to study the rest-frame optical morphology of galaxies at z > 3 and the stellar mass distribution of galaxies at 2 < z < 4.5. We also study the rest-frame optical properties of the 'building blocks' in the field of 53W002 and overall color distribution there. We then combined these data to compare the color and magnitude distribution in these two fields. The opt-NIR color-magnitude distributions in the two fields looks very similar and we report the conspicuous color change below K_AB =22 and discuss the cause of the feature. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0202/0202413v1.pdf"}
{"id": "astro-ph0202461", "abstract": "  We present initial results of an all-sky search for late-type dwarfs within 20 pc of the Sun using the New Luyten Two-Tenths (NLTT) catalog cross-referenced with the 2-Micron All Sky Survey (2MASS) database. The results were obtained with low-resolution optical spectroscopic follow-up of candidate nearby-stars as a preliminary test of our methodology. M_J, derived using spectral indices, and 2MASS J are used to estimate distances. Out of the 70 objects observed, 28 are identified as previously unrecognized objects within 25 pc of the Sun, and up to 19 of these are within 20 pc. One, LP 647-13 is an M9-type dwarf at 10.5 pc making it one of the four closest M9 dwarfs currently known. We also discuss the chromospheric activity of the observed dwarfs. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0202/0202461v2.pdf"}
{"id": "astro-ph0203028", "abstract": "  We have initiated a long-term project, the BOAO photometric survey of open clusters, to enlarge our understanding of galactic structure using UBVI CCD photometry of open clusters which have been little studied before. This is the second paper of the project in which we present the photometry of 12 open clusters. We have determined the cluster parameters by fitting the Padova isochrones to the color-magnitude diagrams of the clusters. All the clusters except for Be 0 and NGC 1348 are found to be intermediate-age to old (0.2 - 4.0 Gyrs) open clusters with a mean metallicity of [Fe/H] = 0.0. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0203/0203028v1.pdf"}
{"id": "astro-ph0203073", "abstract": "  We study the suprathermal electron acceleration mechanism in a perpendicular magnetosonic shock wave in a high Mach number regime by using a particle-in-cell simulation. We find that shock surfing/surftron acceleration producing the suprathermal electrons occurs in the shock transition region where a series of large amplitude electrostatic solitary waves (ESWs) are excited by Buneman instability under the interaction between the reflected ions and the incoming electrons. It is shown that the electrons are likely to be trapped by ESWs, and during the trapping phase they can be effectively accelerated by the shock motional/convection electric field. We discuss that suprathermal electrons can be accelerated up to m_i c^2 (v_0/c), where m_i c^2 is the ion rest mass energy and v_0 is the shock upstream flow velocity. Furthermore, some of these suprathermal electrons may be effectively trapped for infinitely long time when Alfvén Mach number M_A exceeds several 10, and they are accelerated up to the shock potential energy determined by the global shock size. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0203/0203073v1.pdf"}
{"id": "astro-ph0205096", "abstract": "  We have reanalysed constraints on the equation of state parameter, w_Q = P/rho, of the dark energy, using several cosmological data sets and relaxing the usual constraint w_Q > -1. We find that combining Cosmic Microwave Background, large scale structure and Type Ia supernova data yields a non-trivial lower bound on w_Q. At 95.4", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0205/0205096v2.pdf"}
{"id": "astro-ph0211158", "abstract": "  We have observed a sample of Delta Scuti stars discovered by the ROTSE collaboration in 1999 with Super-LOTIS in order to characterize changes in their pulsation periods over a time baseline of roughly three years. Achieving these goals required the creation of an automated astrometric and photometric data reduction pipeline for the Super-LOTIS camera. Applying this pipeline to data from a June 2002 observing campaign, we detect pulsations in 18 objects, and find that in two cases the periods have changed significantly over the three years between the ROTSE and Super-LOTIS observations. Since theory predicts that evolutionary period changes should be quite small, sources of non-evolutionary period changes due to the interactions of pulsations modes are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0211/0211158v1.pdf"}
{"id": "astro-ph0212080", "abstract": "  The majority of Galactic high-energy gamma-ray sources continue to elude identification. Currently, we have a handful of firm pulsar identifications, one of which is radio quiet, and a few marginal detections, including one millisecond pulsar. Recently, both blind searches of EGRET error boxes and targeted searches of X-ray counterpart candidates have had some success in finding new pulsars. I review these results, and discuss our current program of searching mid-Galactic latitude EGRET error boxes using the Parkes multi-beam system. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0212/0212080v1.pdf"}
{"id": "astro-ph0212258", "abstract": "  The AF-supergiants in the Galaxy and the SMC allow us to examine predictions from evolution models through their CNO abundances. In these proceedings, we recalculate the NLTE nitrogen abundances in 22 Galactic and 9 SMC A-supergiants using improved atomic data and model atmospheres to compare with new evolution models. The new abundances are higher than previously published values, and suggest that most of these stars have undergone substantial mixing with CN-cycled gas. While there is no clear relationship with mass, there is an apparent relation with metallicity since the SMC stars (including B-stars) have larger nitrogen enrichments. We suggest that rotational mixing is indicated from the main-sequence throughout the supergiant range, with more substantial rotational mixing in the SMC stars. In addition, the SMC AF-supergiants appear to have undergone the first dredge-up during a previous red giant phase, and possibly the Galactic AF-supergiants have as well. All abundances are compared to the new solar abundances from M. Asplund (this conference). ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0212/0212258v1.pdf"}
{"id": "astro-ph0212486", "abstract": "  We model jets in low-luminosity (FR I) radio galaxies as intrinsically symmetrical, axisymmetric, decelerating relativistic flows with transverse velocity gradients. This allows us to derive velocity fields and the three-dimensional distributions of magnetic-field ordering and rest-frame emissivity. A conservation-law analysis, combining the kinematic model with X-ray observations of the surrounding IGM, gives the profiles of internal density, pressure, Mach number and entrainment rate along the jets. We summarize our recently-published results on 3C 31 and outline new work on other sources and adiabatic jet models. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0212/0212486v1.pdf"}
{"id": "astro-ph0301472", "abstract": "  We investigate the observed depletion of red giants in the cores of post-core-collapse globular clusters. In particular, the evolutionary scenario we consider is a binary consisting of two low-mass stars which undergoes two common envelope phases. The first common envelope phase occurs when the primary is a red giant resulting in a helium white dwarf and main sequence star in a detached binary. The second common envelope phase occurs shortly after the secondary becomes a red giant. During the second common envelope phase the degenerate helium cores merge resulting in a core mass greater than the helium burning limit and the formation of a horizontal branch star. We show that this evolutionary route is enhanced in post-core-collapse clusters by stellar encounters. These encounters increase the population of binary secondaries which would have evolved onto the red giant branch in the recent past. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0301/0301472v1.pdf"}
{"id": "astro-ph0301502", "abstract": "  We present the first high time resolution light curves for six eclipses of the magnetic cataclysmic variable EP Dra, taken using the superconducting tunnel junction imager S-Cam2. The system shows a varying eclipse profile between consecutive eclipses over the two nights of observation. We attribute the variable stream eclipse after accretion region ingress to a variation in the amount and location of bright material in the accretion stream. This material creates an accretion curtain as it is threaded by many field lines along the accretion stream trajectory. We identify this as the cause of absorption evident in the light curves when the system is in a high accretion state. We do not see direct evidence in the light curves for an accretion spot on the white dwarf; however, the variation of the stream brightness with the brightness of the rapid decline in flux at eclipse ingress indicates the presence of some form of accretion region. This accretion region is most likely located at high colatitude on the white dwarf surface, forming an arc shape at the foot points of the many field lines channeling the accretion curtain. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0301/0301502v1.pdf"}
{"id": "astro-ph0302153", "abstract": "  We review our understanding of the prototype “Propeller” system AE Aqr and we examine its flaring behaviour in detail. The flares are thought to arise from collisions between high density regions in the material expelled from the system after interaction with the rapidly rotating magnetosphere of the white dwarf. We show calculations of the time-dependent emergent optical spectra from the resulting hot, expanding ball of gas and derive values for the mass, lengthscale and temperature of the material involved. We see that the fits suggest that the secondary star in this system has reduced metal abundances and that, counter-intuitively, the evolution of the fireballs is best modelled as isothermal. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0302/0302153v1.pdf"}
{"id": "astro-ph0302604", "abstract": "  We note that if the GRB phenomenon follows from the collapse of a massive object forming a black hole and a torus accreting into it, the resulting ejecta can be only related to the mass and angular momentum that characterize the black hole. The opening angle of the fireball then corresponds to a black hole spin. If indeed the fireballs opening angles are as small as recent estimates reported in the literature suggest, then GRB would be produced by almost maximally rotating BH. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0302/0302604v1.pdf"}
{"id": "astro-ph0303129", "abstract": "  We show that the earliest possible reionisation of the Universe is approximately at z≃ 13.5 and the optical depth is τ≃ 0.17 in the conventionally accepted Λ cold dark matter (ΛCDM) model with adiabatic fluctuations of a flat spectrum normalised to the cosmic microwave background. This is consistent with the reionisation found by WMAP (the apparently earlier reionisation epoch of the WMAP is ascribed to the adoption of the instantaneous reionisation approximation), i.e., the WMAP result is realised only if reionisation of the universe takes place nearly at the maximal efficiency in the ΛCDM model. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0303/0303129v3.pdf"}
{"id": "astro-ph0303261", "abstract": "  We show that some characteristics of multiply-imaged QSO systems are very model-independent and can be deduced accurately by simply scrutinizing the relative positions of images and galaxy-lens center. These include the time-ordering of the images, the orientation of the lens potential, and the rough morphology of any ring. Other features can differ considerably between specific models; H_0 is an example. Surprisingly, properties inherited from a circularly symmetric lens system are model-dependent, whereas features that arise from the breaking of circular symmetry are model-independent. We first develop these results from some abstract geometrical ideas, then illustrate them for some well-known systems (the quads Q2237+030, H1413+117, HST14113+5211, PG1115+080, MG0414+0534, B1608+656, B1422+231, and RXJ0911+0551, and the ten-image system B1933+507), and finally remark on two systems (B1359+154 and PMN J0134-0931) where the lens properties are more complex. We also introduce a Java applet which produces simple lens systems, and helps further illustrate the concepts. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0303/0303261v1.pdf"}
{"id": "astro-ph0303435", "abstract": "  Absorption L-lines of iron ions are observed, in absorption, in spectra of Seyfert 1 galaxies by the new generation of X-ray satellites: Chandra (NASA) and XMM-Newton (ESA). Lines associated to Fe23+ to Fe17+ are well resolved. Whereas, those corresponding to Fe16+ to Fe6+ are unresolved. Forbidden transitions of the Fe16+ to Fe6+ ions were previously observed, for the same objects, in the visible and infra-red regions, showing that the plasma had a low density. To interpret X-ray, visible and infra-red data, astrophysical models assume an extended absorbing medium of very low density surrounding an intense X-ray source. We have calculated atomic data (wavelengths, radiative and autoionization rates) for n=2 to n'=3-4 transitions and used them to construct refined synthetic spectra of the unresolved part of the L-line spectra. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0303/0303435v1.pdf"}
{"id": "astro-ph0304310", "abstract": "  We present an analysis of a Chandra observation of Abell 2034. The cluster has multiple signatures of an ongoing merger, including a cold front and probable significant heating of the intracluster medium above its equilibrium temperature. We find no evidence for the large cooling rate previously determined for the cluster, and in fact find it to be roughly isothermal, though with numerous small-scale inhomogeneities, out to a radius of  700 kpc. The cold front appears to be in the process of being disrupted by gas dynamic instability and perhaps by shock heating. We find weak evidence for Inverse Compton hard X-ray emission from the radio relic suspected to be associated with the cold front. Finally, we study the emission to the south of the cluster, which was previously thought to be a merging subcluster. We find no evidence that this \"subcluster\" is interacting with the main Abell 2034 cluster. On the other hand, the properties of this region are inconsistent with an equilibrium cluster at the redshift of Abell 2034 or less. We explore the possibility that it is a disrupted merging subcluster, but find its luminosity to be significantly lower than expected for such a scenario. We suggest that the emission to the south of the cluster may actually be a moderate to high redshift (0.3 < z < 1.25) background cluster seen in projection against Abell 2034. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0304/0304310v1.pdf"}
{"id": "astro-ph0304418", "abstract": "  We study the accuracy with which weak lensing measurements could be made from a future space-based survey, predicting the subsequent precisions of 3-dimensional dark matter maps, projected 2-dimensional dark matter maps, and mass-selected cluster catalogues. As a baseline, we use the instrumental specifications of the Supernova/Acceleration Probe (SNAP) satellite. We first compute its sensitivity to weak lensing shear as a function of survey depth. Our predictions are based on detailed image simulations created using `shapelets', a complete and orthogonal parameterization of galaxy morphologies. We incorporate a realistic redshift distribution of source galaxies, and calculate the average precision of photometric redshift recovery using the SNAP filter set to be Delta z=0.034. The high density of background galaxies resolved in a wide space-based survey allows projected dark matter maps with a rms sensitivity of 3", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0304/0304418v2.pdf"}
{"id": "astro-ph0308319", "abstract": "  We report on a spatially resolved analysis of Chandra X-ray data on a nearby typical cooling flow cluster of galaxies 2A 0335+096, together with A 2199 for a comparison. As recently found in the cores of other clusters, the temperature around the central part of 2A 0335+096 is 1.3–1.5 keV, which is higher than that inferred from the cooling flow picture. Furthermore, the absorption column density is almost constant against the radius in 2A 0335+096; there is no evidence of excess absorption up to 200–250 kpc. This indicates that no significant amount of cold material, which has cooled down, is present. These properties are similar to those of A 2199. Since the cooling time in the central part is much shorter than the age of the clusters, a heating mechanism, which weakens the effect of radiative cooling, is expected to be present in the central part of both clusters of galaxies. Both 2A 0335+096 and A 2199 have radio jets associated with their cD galaxy. We discuss the possibility of heating processes caused by these radio jets by considering the thermal conduction and the sound velocity together with the observed disturbance of the ICM temperature and density. We conclude that the observed radio jets can produce local heating and/or cooling, but do not sufficiently reduce the overall radiative cooling. This implies that much more violent jets, whose emission has now decayed, heated up the cooling gas >10^9 years ago. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0308/0308319v1.pdf"}
{"id": "astro-ph0308358", "abstract": "  We present global 2-D inviscid disk simulations with an embedded planet, emphasizing the non-linear dynamics in its co-orbital region. We find that the potential vorticity of the flow in this region is not conserved due to the presence of two spiral shocks produced by the planet. As the system evolves, the potential vorticity profile develops extrema (inflection points) which eventually render the flow unstable. Vortices are produced in association with the potential vorticity minima. Born in the separatrix region, these vortices experience close-encounters with the planet, consequently exerting strong torques on the planet. The existence of these vortices have important implications on understanding the migration rates of low mass planets. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0308/0308358v1.pdf"}
{"id": "astro-ph0309376", "abstract": "  In this paper we provide approximate analytical analysis of stability of nonsingular inflationary chaotic-type cosmological models. Initial conditions for nonsingular solutions at the bounce correspond to dominance of potential part of the energy density of the scalar field over its kinetic part both within general relativity and gauge theories of gravity. Moreover, scalar field at the bounce exceeds the planckian value and on expansion stage these models correspond to chaotic inflation. Such solutions can be well approximated by explicitly solvable model with constant effective potential (cosmological term) and massless scalar field during the bounce and on stages of quasi-exponential contraction and expansion. Perturbative analysis shows that nonsingular inflationary solutions are exponentially unstable during contraction stage. This result is compared with numerical calculations. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0309/0309376v3.pdf"}
{"id": "astro-ph0309752", "abstract": "  The plethora of asymmetric planetary nebulae and the curiously high momenta of pre-planetary nebula outflows suggest that rotational energy is extracted from the engines. Magneto-rotational outflows driven by dynamos might be operating therein. I summarize scenarios involving (a) an isolated AGB star and (b) a binary. The efficacy of (a) requires re-establishing differential rotation over the AGB star's lifetime, whereas (b) delivers the angular momentum at the end of the AGB phase when needed, and may involve turbulent disks. Both can produce fields that drive outflows of the required mechanical luminosity and momentum, though weak points and open questions require further study. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0309/0309752v1.pdf"}
{"id": "astro-ph0310078", "abstract": "  In previous work we found that many of the spectral properties of low mass x-ray binaries, including galactic black hole candidates could be explained by a magnetic propeller model that requires an intrinsically magnetized central object. Here we describe how the Einstein field equations of General Relativity and equipartition magnetic fields permit the existence of highly red shifted, extremely long lived, collapsing, radiating objects. We examine the properties of these collapsed objects and discuss characteristics that might lead to their confirmation as the source of black hole candidate phenomena. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0310/0310078v1.pdf"}
{"id": "astro-ph0310430", "abstract": "  We determine the possible detection rate of asteroids with the Bering mission. In particular we examine the outcome of the Bering mission in relation to the populations of Near-Earth Asteroids and main belt asteroids. This is done by constructing synthetic populations of asteroids, based on the current best estimates of the asteroid size-distributions. From the detailed information obtained from the simulations, the scientific feasibility of Bering is demonstrated and the key technical requirement for the scientific instruments on Bering is determined. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0310/0310430v1.pdf"}
{"id": "astro-ph0312339", "abstract": "  The study of the evolution of a suprathermal electron beam traveling through a background plasma is relevant for the physics of solar flares and their associated type III solar radio bursts. As they evolve guided by the coronal magnetic field-lines, these beams generate Langmuir turbulence. The beam-generated turbulence is in turn responsible for the emission of radio photons at the second harmonic of the local plasma frequency, which are observed during type III solar radio bursts. To generate the radio emission, the beam-aligned Langmuir waves must coalesce, and therefore a process capable of re-directioning the turbulence in an effective fashion is required.   Different theoretical models identify the electrostatic (ES) decay process L1 -> L2 + S (L: Langmuir wave; S: Ion-acoustic wave) as the re-directioning mechanism for the L waves. Two different regimes have been proposed to play a key role: the back-scattering and the diffusive (small angle) scattering. This paper is a comparative analysis of the decay rate of the ES decay for each regime, and of the different observable characteristics that are expected for the resulting ion-acoustic waves. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0312/0312339v1.pdf"}
{"id": "astro-ph0401150", "abstract": "  Here we propose that the excess flux of particle events of energy near 1 EeV from the direction of the Galactic Center region is due to the production of cosmic rays by the last few Gamma Ray Bursts in our Galaxy. The basic idea is that protons get accelerated inside Gamma Ray Bursts, then get ejected as neutrons, decay and so turn back into protons, meander around the inner Galaxy for some time, and then interact again, turning back to neutrons to be observed at our distance from the Galactic Center region, where most star formation is happening in our Galaxy. We demonstrate that this suggestion leads to a successful interpretation of the data, within the uncertainties of cosmic ray transport time scales in the inner Galaxy, and in conjunction with many arguments in the literature. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0401/0401150v1.pdf"}
{"id": "astro-ph0401186", "abstract": "  We review recent observations of molecular gas in nearby galaxies and their implications for the star formation law on large (>1 kpc) scales. High-resolution data provided by millimetre interferometers are now adding to the basic understanding that has been provided by single-dish telescopes. In particular, they confirm the good correlation between star formation rate (SFR) and molecular gas surface densities, while at the same time revealing a greater degree of heterogeneity in the CO distribution. Galaxies classified as SAB or SB tend to show radial CO profiles that peak sharply in the inner  20 arcsec, indicative of bar-driven inflow. The observed Schmidt law index of  1.5 may result from a nearly linear relation between SFR and H_2 mass coupled with a modest dependence of the molecular gas fraction on the total gas density. The normalisation of the Schmidt law, giving the characteristic timescale for star formation, may stem from the generic nature of interstellar turbulence. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0401/0401186v1.pdf"}
{"id": "astro-ph0402122", "abstract": "  We discuss the Skyrme model for strong interactions and the concept of a Skyrmion fluid. The corresponding compact objects, namely Skyrmion stars, constructed from the equation of state describing such a fluid are presented and compared to models of neutron stars based on modern equation of states. We suggest plausible Skyrmion star candidates in the 4U 1636-53 and 4U 1820-30 low mass X-ray binary systems where the suggested masses of the accreting compact companion (∼2.0M_⊙) remain a challenge for neutron star models. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0402/0402122v1.pdf"}
{"id": "astro-ph0404323", "abstract": "  In order to understand the nature of magnetic reconnection in “free space” which is free from any influence of external circumstances, I have studied the structure of spontaneous reconnection outflow using a shock tube approximation. The reconnection system of this case continues to expand self-similarly. This work aims 1) to solve the structure of reconnection outflow and 2) to clarify the determination mechanism of reconnection rate of the “self-similar evolution model” of fast reconnection.   Many cases of reconnection in astrophysical phenomena are characterized by a huge dynamic range of expansion in size (∼ 10^7 for typical solar flares). Although such reconnection is intrinsically time dependent, a specialized model underlying the situation has not been established yet.   The theoretical contribution of this paper is in obtaining a solution for outflow structure which is absent in our previous papers proposing the above new model. The outflow has a shock tube-like structure, i.e., forward slow shock, reverse fast shock and contact discontinuity between them. By solving the structure in a sufficiently wide range of plasma-β: 0.001 ≤β≤ 100, we obtain an almost constant reconnection rate (∼ 0.05: this value is the maximum for spontaneous reconnection and is consistent with previous models) and a boundary value along the edge of the outflow (good agreement with our simulation result) which is important to solve the inflow region. Note that everything, including the reconnection rate, is spontaneously determined by the reconnection system itself in our model. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0404/0404323v2.pdf"}
{"id": "astro-ph0404498", "abstract": "  We present the preliminary results of 235 MHz, 327 MHz and 610 MHz observations of the galaxy cluster A3562 in the core of the Shapley Concentration. The purpose of these observations, carried out with the Giant Metrewave Radio Telescope (GMRT, Pune, India) was to study the radio halo located at the centre of A3562 and determine the shape of its radio spectrum at low frequencies, in order to understand the origin of this source. In the framework of the re–acceleration model, the preliminary analysis of the halo spectrum suggests that we are observing a young source (few 10^8 yrs) at the beginning of the re–acceleration phase. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0404/0404498v1.pdf"}
{"id": "astro-ph0405408", "abstract": "  We present maps of the nature of single star progenitors of supernovae and their remnants in mass and metallicity space. We find our results are similar to others but we have gone further in varying the amount of mixing and using various mass-loss schemes to see how the maps change. We find that extra-mixing, in the form of convective overshooting, moves boundaries such as the minimum mass for a supernova or WR star to lower masses. We also find that the pre-WR mass-loss determines the shape of our maps. We find that different mass-loss rates lead to quite different results. We find that the rise in luminosity at 2nd dredge-up places quite tight constraints on the masses of some progenitors and in particular the progenitor of supernova 2003gd. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0405/0405408v2.pdf"}
{"id": "astro-ph0406343", "abstract": "  In this paper we discuss the possibility to measure the Hubble parameter and the slope of galaxy density profiles using future supernova data. With future supernova surveys such as SNAP, large numbers of core collapse supernovae will be discovered, a small fraction of which will be multiply imaged. Measurements of the image separation, flux-ratio, time-delay and lensing foreground galaxy for these systems will provide tight constraints on the slope of galactic halos as well as providing complementary and independent information to other cosmological tests with respect to the Hubble parameter. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0406/0406343v2.pdf"}
{"id": "astro-ph0407244", "abstract": "  This paper consists of two sections. In the first section, we discuss our fits to the latest HiRes monocular spectra. We find that the best fit for the extragalactic component has a spectral index of γ=-2.38±0.04 with a distribution of sources varying with a evolution parameter m=2.8±0.3. In the second section, we discuss preliminary results from a new composition measurement using HiRes monocular data. We find a predominantly light spectrum above 10^17.6 eV. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0407/0407244v1.pdf"}
{"id": "astro-ph0408579", "abstract": "  We study the dynamics of a charged particle in the field of a slowly rotating compact star in the gravitoelectromagnetic approximation to the geodesic equation . The star is assumed to be surrounded by an ideal, highly conducting plasma (taken as a magnetohydrodynamic fluid) with a stationary, axially symmetric electromagnetic field. The general relativistic Maxwell equations are solved to obtain the effects of the background spacetime on the electromagnetic field in the linearized Kerr spacetime. The equations of motion are then set up and solved numerically to incorporate the gravitational as well as the electromagnetic effects. The analysis shows that in the slow rotation approximation the frame dragging effects on the electromagnetic field are absent. However the particle is directly effected by the rotating gravitational source such that close to the star the gravitational and electromagnetic field produce contrary effects on the particle's trajectory. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0408/0408579v2.pdf"}
{"id": "astro-ph0409385", "abstract": "  The outer region (0.75–1.25 r_e in the B-band) of the merger-remnant elliptical NGC 3610 is studied using extremely high signal to noise Keck spectra, with a supplementary spectrum of the galaxy center. Stellar population parameters – age, [Z/H], [α/Fe] – are measured in several apertures along the slit. Using the multi-index simultaneous fitting method of Proctor et al. (2004), no significant stellar population gradients are detected in the outer parts of the galaxy. The overall gradients relative to the galaxy center are consistent with those found in many other early-type galaxies, though the metallicity gradient is much steeper than would be expected if NGC 3610 formed in a major merger event. Standard analysis methods using the Hβ index are found to produce spurious radially variable gradients. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0409/0409385v1.pdf"}
{"id": "astro-ph0410071", "abstract": "  We raise the question whether in the past a disk could have existed in our Galactic Center which has disappeared now. Our model for the interaction of a cool disk and a hot corona above (Liu et al. 2004) allows to estimate an upper limit for the mass that might have been present in a putative accretion disk after a last star forming event, but would now have evaporated by coronal action. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0410/0410071v1.pdf"}
{"id": "astro-ph0410263", "abstract": "  We present the first results of a campaign to obtain orbital solutions of subdwarf B (sdB) stars from the Edinburgh-Cape survey. We have obtained blue spectra of 35 sdBs, 20 of which have been observed in more than two epochs. 15 out of the 35 are certain binaries with a few other objects showing radial velocity variations with small amplitude, possibly long period sdB binaries. We have secured the orbital parameters for 2 of the 15 systems and narrowed down the orbits of another one to a small range of periods. These preliminary results only use data taken up to December 2003. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0410/0410263v1.pdf"}
{"id": "astro-ph0410668", "abstract": "  Supernovae (SNe) were long suspected as possible progenitors of gamma-ray bursts (GRBs). The arguments relied on circumstantial evidence. Several recent GRBs, notably GRB 030329, have provided direct, spectroscopic evidence that SNe and GRBs are related. The SNe associated with GRBs are all of Type Ic, implying a compact progenitor, which has implications for GRB models. Other peculiar Type Ic SNe may help to expand understanding of the mechanisms involved. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0410/0410668v1.pdf"}
{"id": "astro-ph0412047", "abstract": "  A prototype of the MeV gamma-ray imaging camera based on the full reconstruction of the Compton process has been developed. This camera consists of a micro-TPC that is a gaseous Time Projection Chamber (TPC) and scintillation cameras. With the information of the recoil electrons and the scattered gamma-rays, this camera detects the energy and incident direction of each incident gamma-ray. We developed a prototype of the MeV gamma-ray camera with a micro-TPC and a NaI(Tl) scintillator, and succeeded in reconstructing the gamma-rays from 0.3 MeV to 1.3 MeV. Measured angular resolutions of ARM (Angular Resolution Measure) and SPD (Scatter Plane Deviation) for 356 keV gamma-rays were 18^∘ and 35^∘, respectively. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0412/0412047v1.pdf"}
{"id": "astro-ph0412109", "abstract": "  Recent microscopic and phenomenological calculations of giant dipole resonances for A <= 56 nuclei are presented. The derived photodisintegration cross sections are exhaustively compared to the photonuclear data available to date. An accurate description of the data is found. Our new calculations are also compared with the previous and widely-used estimates of Puget, Stecker and Bredekamp. The present calculations also include all the possible paths down the nuclear chart. The impact on the photodisintegration of ultra-high-energy cosmic rays (UHECR) is illustrated for a Fe source with typical energies of 10^20-21 eV. At energies around 10^20 eV, the new cross sections are found to modify the UHECR photodisintegration rates. At energies around 10^21 eV, it is recommended to solve a full reaction network to estimate the photodisintegration rate of the UHECR. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0412/0412109v1.pdf"}
{"id": "astro-ph0412286", "abstract": "  We report on first results of XMM-Newton observations of nearby starburst galaxies that form part of a multi-wavelength study of gaseous halos around late-type spiral galaxies and their dependence on the level of star formation activity in the underlying disks. XMM-Newton, with its extraordinary sensitivity for faint extended X-ray emission, is used to derive spatial and spectral properties of the very hot extraplanar/halo gas. For example, spectral models can be tested and hot gas properties like density, mass and energy can be estimated. Comparing the distribution of the halo X-ray emission with optical filaments and/or observed magnetic field structures uncovers interesting correlations on which work just has started. Our study aims - in general - at assessing the importance of galactic halos as repositories of a metal-enriched hot medium and their significance in terms of galactic chemical evolution and possible metal enrichment of the intergalactic medium. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0412/0412286v1.pdf"}
{"id": "astro-ph0502371", "abstract": "  We study the magnetic interaction between a neutron star and its disk by solving the time-dependent relativistic force-free equations. At the initial state, we assume that the dipole magnetic field of the neutron star connects the neutron star and its equatorial disk, which deeply enters into the magnetosphere of the neutron star. Magnetic fields are assumed to be frozen to the star and the disk. The rotation of the neutron star and the disk is imposed as boundary conditions. We apply Harten-Lax-van Leer (HLL) method to simulate the evolution of the star-disk system. We carry out simulations for (1) a disk inside the corotation radius, in which the disk rotates faster than the star, and (2) a disk outside the corotation radius, in which the neutron star rotates faster than the disk. Numerical results indicate that for both models, the magnetic field lines connecting the disk and the star inflate as they are twisted by the differential rotation between the disk and the star. When the twist angle exceeds pi radian, the magnetic field lines expand with speed close to the light speed. This mechanism can be the origin of relativistic outflows observed in binaries containing a neutron star. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0502/0502371v1.pdf"}
{"id": "astro-ph0502536", "abstract": "  Debris rings of dust are found around young luminous stars such as HR4796A and HD141569. Some of these entities have sharp edges and gaps which have been interpreted as evidence for the presence of shepherding and embedded planets. Here we show that gaps and sharp edges in the debris disks of dust can also be spontaneously self generated if they are embedded in optically thin regions of gaseous disks. This clumping instability arises in regions where an enhancement in the dust density leads to local gas temperature and pressure increases. Consequently, the relative motion between the gas and the dust is modified. The subsequent hydrodynamic drag on the dust particles leads to further enhancement of their concentration. We show that this process is linearly unstable and leads to the formation of ring-like structures within the estimated life time of such young objects. Once the gas is removed (e.g. by photo evaporation) the structures are “frozen” and will persist, even when the gas might not be observable anymore. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0502/0502536v2.pdf"}
{"id": "astro-ph0503147", "abstract": "  We use exact orbit integration to investigate particle acceleration in a Gauss field proxy of magnetohydrodynamic (MHD) turbulence. Regions where the electric current exceeds a critical threshold are declared to be `dissipative' and endowed with super-Dreicer electric field E_Ω = η j. In this environment, test particles (electrons) are traced and their acceleration to relativistic energies is studied. As a main result we find that acceleration mostly takes place within the dissipation regions, and that the momentum increments have heavy (non-Gaussian) tails, while the waiting times between the dissipation regions are approximately exponentially distributed with intensity proportional to the particle velocity. No correlation between the momentum increment and the momentum itself is found. Our numerical results suggest an acceleration scenario with ballistic transport between independent `black box' accelerators. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0503/0503147v1.pdf"}
{"id": "astro-ph0503701", "abstract": "  We use cosmological SPH simulations to investigate the effects of mergers and interactions on the formation of the bulge and disc components of galactic systems. We find that secular evolution during mergers seems to be a key process in the formation of stable disc-bulge systems with observational counterparts and contributes to establish the fundamental relations observed in galaxies. Our findings suggest that the secular evolution phase couples the formation mechanisms of the bulge and disc components. According to our results, depending on the particular stability properties and merger parameters, violents events could drive a morphological loop in which the outcome could be a disc or a spheroid. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0503/0503701v1.pdf"}
{"id": "astro-ph0504367", "abstract": "  The twin Pioneer spacecraft have been tracked for over thirty years as they headed out of the solar system. After passing 20 AU from the Sun, both exhibited a systematic error in their trajectories that can be interpreted as a constant acceleration towards the Sun. This Pioneer Effect is most likely explained by spacecraft systematics, but there have been no convincing arguments that that is the case. The alternative is that the Pioneer Effect represents a real phenomenon and perhaps new physics. What is lacking is a means of measuring the effect, its variation, its potential anisotropies, and its region of influence. We show that minor planets provide an observational vehicle for investigating the gravitational field in the outer solar system, and that a sustained observation campaign against properly chosen minor planets could confirm or refute the existence of the Pioneer Effect. Additionally, even if the Pioneer Effect does not represent a new physical phenomenon, minor planets can be used to probe the gravitational field in the outer Solar System and since there are very few intermediate range tests of gravity at the multiple AU distance scale, this is a worthwhile endeavor in its own right. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0504/0504367v3.pdf"}
{"id": "astro-ph0504431", "abstract": "  Using the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope, we have obtained rest frame mid-infrared spectroscopy of two bright submillimeter galaxies. SMMJ02399-0136 at z=2.81 shows a superposition of PAH emission features and a mid-infrared continuum, indicating significant and roughly equal contributions to its bolometric luminosity from star formation and from a Compton-thick AGN. We derive a new redshift of z=2.80 for MMJ154127+6616 from the IRS spectrum and find this object is dominated by starburst PAH emission. The rest frame mid- to far-infrared spectral energy distributions are consistent with these submillimeter galaxies being scaled up versions of local ultraluminous infrared galaxies. The mid-infrared spectra support the scenario that submillimeter galaxies are sites of extreme star formation and represent a key phase in the formation of massive galaxies. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0504/0504431v1.pdf"}
{"id": "astro-ph0504539", "abstract": "  I discuss the interpretation of the prompt phase in gamma-ray bursts as being dominated by quasi-thermal emission, rather than by synchrotron emission. Such an interpretation gives a more natural explanation of (i) the observed variety of spectral shape and spectral evolution, (ii) the observed narrowness of the distribution of peak energies, as well as (iii) the observed correlations between peak energy and luminosity. However, the physical setting that could produce such a scenario is not yet clear. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0504/0504539v1.pdf"}
{"id": "astro-ph0504668", "abstract": "  A homogeneous sample comprising host galaxies of 604 recent supernovae, including 212 objects discovered primarily in 2003 and 2004, has been classified on the David Dunlap Observatory system. Most SN 1991bg-like SNe Ia occur in E and E/Sa galaxies, whereas the majority of SN 1991T-like SNe Ia occur in intermediate-type galaxies. This difference is significant at the 99.9", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0504/0504668v1.pdf"}
{"id": "astro-ph0505450", "abstract": "  We present new sequences of general relativistic, quasiequilibrium black hole-neutron star binaries. We solve for the gravitational field in the conformal thin-sandwich decomposition of Einstein's field equations, coupled to the equations of relativistic hydrostatic equilibrium for a perfect fluid. We account for the black hole by solving these equations in the background metric of a Schwarzschild black hole whose mass is much larger than that of the neutron star. The background metric is treated in Kerr-Schild as well as isotropic coordinates. For the neutron star, we assume a polytropic equation of state with adiabatic index Gamma=2, and solve for both irrotational and corotational configurations. By comparing the results of irrotational and synchronized configurations with the same background metric, we conclude that the effect of the rotation on the location of tidal break-up is only on the order of a few percent. The different choices in the background also lead to differences of order a few percent, which may be an indication of the level to which these configurations approximate quasiequilibrium. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0505/0505450v3.pdf"}
{"id": "astro-ph0505534", "abstract": "  We report the first quiescent detection of KV UMa, the optical counterpart of XTE J1118+480 at near infrared. The observed magnitudes and colours are consistent with a K7-M0 V star, at the distance 1.4 +/- 0.2 kpc. The light curve shows strong orbital modulation with possible contamination from a superhump detected in the quiescent optical light curves. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0505/0505534v1.pdf"}
{"id": "astro-ph0506518", "abstract": "  We study the applicability of several galaxy environment measures (n^th-nearest-neighbor distance, counts in an aperture, and Voronoi volume) within deep redshift surveys. Mock galaxy catalogs are employed to mimic representative photometric and spectroscopic surveys at high redshift (z   1). We investigate the effects of survey edges, redshift precision, redshift-space distortions, and target selection upon each environment measure. We find that even optimistic photometric redshift errors (σ_z = 0.02) smear out the line-of-sight galaxy distribution irretrievably on small scales; this significantly limits the application of photometric redshift surveys to environment studies. Edges and holes in a survey field dramatically affect the estimation of environment, with the impact of edge effects depending upon the adopted environment measure. These edge effects considerably limit the usefulness of smaller survey fields (e.g. the GOODS fields) for studies of galaxy environment. In even the poorest groups and clusters, redshift-space distortions limit the effectiveness of each environment statistic; measuring density in projection (e.g. using counts in a cylindrical aperture or a projected n^th-nearest-neighbor distance measure) significantly improves the accuracy of measures in such over-dense environments. For the DEEP2 Galaxy Redshift Survey, we conclude that among the environment estimators tested the projected n^th-nearest-neighbor distance measure provides the most accurate estimate of local galaxy density over a continuous and broad range of scales. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0506/0506518v1.pdf"}
{"id": "astro-ph0506684", "abstract": "  In this paper we present and discuss a new Monte Carlo approach aimed at correcting the observed Supernova (SN) rates for the effects of host galaxy dust extinction. The problem is addressed in a general way and the model includes SN position distributions, SN light curve and spectral library, dust properties and distribution as input ingredients. Even though the recipe we propose is in principle applicable to all SN types, in this paper we illustrate the use of our model only for Type Ia. These represent in fact the simplest test case, basically due to their spectroscopic homogeneity which, to a first approximation, allows one to treat them all in the same way. This test case shows that the final results do not depend critically on the spiral arm dust geometry, while the total amount of dust, its properties and the size of the galactic bulge do have a strong effect. With the availability of more complete spectral libraries and a more accurate knowledge of SN spatial distribution, the method we propose here can be easily extended to Core Collapses events. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0506/0506684v1.pdf"}
{"id": "astro-ph0507508", "abstract": "  The Abell 1689 galaxy cluster has recently become a subject of intensive study. Thanks to its intermediate redshift (z=0.183) its mass distribution can be reconstructed using numerous methods including gravitational lensing, galaxy kinematics and X-ray imaging. The methods used to yield conflicting mass estimates in the past and recently the cluster mass distribution has been claimed to be in conflict with standard CDM scenarios due to rather large concentration and steep mass profile obtained from detailed studies of Broadhurst et al. using lensing. By studying in detail the kinematics of about 200 galaxies with measured redshifts in the vicinity of the cluster we show that the cluster is probably surrounded by a few structures, quite distant from each other, but aligned along the line of sight. We support our arguments by referring to cosmological N-body simulations and showing explicitly that distant, non-interacting haloes can produce entangled multi-peak line-of-sight velocity distributions similar to that in A1689. We conclude that it is difficult to estimate the cluster mass reliably from galaxy kinematics, but the value we obtain after applying a simple cut-off in velocity agrees roughly with the mass estimated from lensing. The complicated mass distribution around the cluster may however increase the uncertainty in the determination of the density profile shape obtained with weak lensing. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0507/0507508v2.pdf"}
{"id": "astro-ph0507561", "abstract": "  We have studied the power spectrum and the intermittent behavior of the fluctuations in the transmitted flux of HE2347-4342 Lyα absorption in order to investigate if there is any discrepancy between the LCDM model with parameters given by the WMAP and observations on small scales. If the non-Gaussianity of cosmic mass field is assumed to come only from halos with an universal mass profile of the LCDM model, the non-Gaussian behavior of mass field would be effectively measured by its intermittency, because intermittency is a basic statistical feature of the cuspy structures. We have shown that the Lyα transmitted flux field of HE2347-4342 is significantly intermittent on small scales. With the hydrodynamic simulation, we demonstrate that the LCDM model is successful in explaining the power spectrum and intermittency of Lyα transmitted flux. Using statistics ranging from the second to eighth order, we find no discrepancy between the LCDM model and the observed transmitted flux field, and no evidence to support the necessity of reducing the power of density perturbations relative to the standard LCDM model up to comoving scales as small as about 0.08  h^-1 Mpc. Moreover, our simulation samples show that the intermittent exponent of the Lyα transmitted flux field is probably scale-dependent. This result is different from the prediction of universal mass profile with a constant index of the central cusp. The scale-dependence of the intermittent exponent indicates that the distribution of baryonic gas is decoupled from the underlying dark matter. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0507/0507561v1.pdf"}
{"id": "astro-ph0508510", "abstract": "  We present the results of a systematical analysis of the intrinsic optical afterglow light curves for a complete sample of gamma-ray bursts (GRBs) observed in the period from Feb. 1997 to Aug. 2005. These light curves are generally well-sampled, with at least four detections in the R band. The redshifts of all the bursts in the sample are available. We derive the intrinsic R band afterglow lightcurves (luminosity versus time within the cosmic proper rest frame) for these GRBs, and discover a fact that they essentially follow two universal tracks after 2 hours since the GRB triggers. The optical luminosities at 1 day show a clear bimodal distribution, peaking at 1.4*10^46 ergs s^-1 for the luminous group and 5.3*10^44 ergs s^-1 for the dim group. About 75", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0508/0508510v2.pdf"}
{"id": "astro-ph0509257", "abstract": "  The first well-localized short-duration gamma ray bursts (GRBs), GRB 050509b, GRB 050709 and GRB 050724, could have been the narrowly beamed initial spike of a burst/hyper flare of soft gamma ray repeaters (SGRs) in host galaxies at cosmological distances. Such bursts are expected if SGRs are young hyperstars, i.e. neutron stars where a considerable fraction of their neutrons have converted to hyperons and/or strange quark matter. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0509/0509257v1.pdf"}
{"id": "astro-ph0509769", "abstract": "  We have searched the region surrounding the Crab Nebula for the existence of a shock wave with the imaging instruments of the Einstein Observatory. The search is complicated by the scattering of nebula and pulsar X-rays from the imperfectly polished surfaces of the telescope mirror, as well as from interstellar grains along the line of sight. Both of these effects lead to the appearance of X-ray emission, in the form of an X-ray halo, beyond the boundaries of the nebula filaments.   We show that the size, shape, and intensity of the halo around the Crab Nebula, above the contribution of mirror scattering, is consistent with what is expected from the scattering from interstellar grains. The upper limit on the X-ray emission from a shock wave is about 1", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0509/0509769v1.pdf"}
{"id": "astro-ph0510618", "abstract": "  Under the hypothesis that Gamma Ray Burst (GRB) might be responsible for the origin of Ultra High Energy Cosmic Ray (UHECR), we propose a two component (galactic and extra-galactic) model for the UHECR origin. The model is based on two facts. The first is the anisotropies found in the angular distribution of GRBs from BATSE catalog. Second is that, of all the located long-GRBs, only approximately 15 percent of them have their spectroscopic redshift determined, and some 38 percent of them have a X-ray, optical, or radio afterglow. So far, in short-GRBs, no afterglow and no red shift have been detected, suggesting that these GRB sources are inside or close to our Galaxy. This two component model for the UHECR is further supported by the experimental evidences of an UHECR excess around 10^18 eV from the direction of the galactic central region. The model offers in a natural way an explanation for the presence of cosmic rays with energies beyond the Greisen-Zatsepin-Kuz'min (GZK) cutoff. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0510/0510618v1.pdf"}
{"id": "astro-ph0511325", "abstract": "  The effects of turbulence on the mixing of gases and dust in the outer Solar nebula are examined using 3-D MHD calculations in the shearing-box approximation with vertical stratification. The turbulence is driven by the magneto-rotational instability. The magnetic and hydrodynamic stresses in the turbulence correspond to an accretion time at the midplane about equal to the lifetimes of T Tauri disks, while accretion in the surface layers is thirty times faster. The mixing resulting from the turbulence is also fastest in the surface layers. The mixing rate is similar to the rate of radial exchange of orbital angular momentum, so that the Schmidt number is near unity. The vertical spreading of a trace species is well-matched by solutions of a damped wave equation when the flow is horizontally-averaged. The damped wave description can be used to inexpensively treat mixing in 1-D chemical models. However, even in calculations reaching a statistical steady state, the concentration at any given time varies substantially over horizontal planes, due to fluctuations in the rate and direction of the transport. In addition to mixing species that are formed under widely varying conditions, the turbulence intermittently forces the nebula away from local chemical equilibrium. The different transport rates in the surface layers and interior may affect estimates of the grain evolution and molecular abundances during the formation of the Solar system. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0511/0511325v1.pdf"}
{"id": "astro-ph0512326", "abstract": "  Over much of the initial mass function, stars are destined to become luminous and cool red giants. They may then be able to produce dust in an atmosphere which has been elevated by strong radial pulsations, and hence drive a wind. The amount of mass that is lost in this way can be a very significant fraction of the stellar mass, and especially in the case of intermediate-mass stars it is highly enriched. The delay between a star's birth and its feedback into the environment varies from several million years for massive stars to almost the age of the Universe for the least massive red giants we see today. I here present a review on the metallicity dependence of red giant winds. I show that recent measurements not only confirm theoretical expectations, but also admonish of common misconceptions with implications for feedback at low initial metallicity. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0512/0512326v1.pdf"}
{"id": "astro-ph0602136", "abstract": "  We show that the very close-by (19 pc) K0 star HD 189733, already found to be orbited by a transiting giant planet, is the primary of a double-star system, with the secondary being a mid-M dwarf with projected separation of about 216 AU from the primary. This conclusion is based on astrometry, proper motion and radial velocity measurements, spectral type determination and photometry. We also detect differential proper motion of the secondary. The data appear consistent with the secondary orbiting the primary in a clockwise orbit, lying nearly in the plane of the sky (that is, nearly perpendicular to the orbital plane of the transiting planet), and with period about 3200 years. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0602/0602136v1.pdf"}
{"id": "astro-ph0603082", "abstract": "  Cool giant and supergiant stars generally present low velocity winds with high mass loss rates. Several models have been proposed to explain the acceleration process of these winds. Although dust is known to be present in these objects, the radiation pressure on these particles is uneffective in reproducing the observed physical parameters of the wind. The most promising acceleration mechanism cited in the literature is the transference of momentum and energy from Alfven waves to the gas. Usually, these models consider the wind to be isothermal. We present a stellar wind model in which the Alfven waves are used as the main acceleration mechanism, and determine the temperature profile by solving the energy equation taking into account both the radiative losses and the wave heating. We also determine self-consistently the magnetic field geometry as the result of the competition between the magnetic field and the thermal pressures gradient. As main result, we show that the magnetic geometry present a super-radial index in the region where the gas pressure is increasing. However, this super-radial index is greater than that observed for the solar corona. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0603/0603082v1.pdf"}
{"id": "astro-ph0603514", "abstract": "  We derived the black hole fundamental plane relationship among the 1.4GHz radio luminosity (L_r), 0.1-2.4keV X-ray luminosity (L_X), and black hole mass (M) from a uniform broad line SDSS AGN sample including both radio loud and radio quiet X-ray emitting sources. We found in our sample that the fundamental plane relation has a very weak dependence on the black hole mass, and a tight correlation also exists between the Eddington luminosity scaled X-ray and radio luminosities for the radio quiet subsample. Additionally, we noticed that the radio quiet and radio loud AGNs have different power-law slopes in the radio–X-ray non-linear relationship. The radio loud sample displays a slope of 1.39, which seems consistent with the jet dominated X-ray model. However, it may also be partly due to the relativistic beaming effect. For radio quiet sample the slope of the radio–X-ray relationship is about 0.85, which is possibly consistent with the theoretical prediction from the accretion flow dominated X-ray model. We briefly discuss the reason why our derived relationship is different from some previous works and expect the future spectral studies in radio and X-ray bands on individual sources in our sample to confirm our result. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0603/0603514v1.pdf"}
{"id": "astro-ph0604362", "abstract": "  The baryon acoustic oscillations are a promising route to the precision measure of the cosmological distance scale and hence the measurement of the time evolution of dark energy. We show that the non-linear degradation of the acoustic signature in the correlations of low-redshift galaxies is a correctable process. By suitable reconstruction of the linear density field, one can sharpen the acoustic peak in the correlation function or, equivalently, restore the higher harmonics of the oscillations in the power spectrum. With this, one can achieve better measurements of the acoustic scale for a given survey volume. Reconstruction is particularly effective at low redshift, where the non-linearities are worse but where the dark energy density is highest. At z=0.3, we find that one can reduce the sample variance error bar on the acoustic scale by at least a factor of 2 and in principle by nearly a factor of 4. We discuss the significant implications our results have for the design of galaxy surveys aimed at measuring the distance scale through the acoustic peak. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0604/0604362v1.pdf"}
{"id": "astro-ph0604441", "abstract": "  Although kilometer-scale neutrino detectors such as IceCube are discovery instruments, their conceptual design is very much anchored to the observational fact that Nature produces protons and photons with energies in excess of 10^20 eV and 10^13 eV, respectively. The puzzle of where and how Nature accelerates the highest energy cosmic particles is unresolved almost a century after their discovery. We will discuss how the cosmic ray connection sets the scale of the anticipated cosmic neutrino fluxes. In this context, we discuss the first results of the completed AMANDA detector and the science reach of its extension, IceCube. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0604/0604441v1.pdf"}
{"id": "astro-ph0605330", "abstract": "  We have analyzed both archival and new infrared imaging observations of the field of the Anomalous X-ray Pulsar 1RXS J170849.0-400910, in search of the infrared counterpart. This field has been previously investigated, and one of the sources consistent with the position of the AXP suggested as the counterpart. We, however, find that this object is more likely a background star, while another object within the positional error circle has non-stellar colors and shows evidence for variability. These two pieces of evidence, along with a consistency argument for the X-ray-to-infrared flux ratio, point to the second source being the more likely infrared counterpart to the AXP. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0605/0605330v1.pdf"}
{"id": "astro-ph0605595", "abstract": "  In this review we present a brief discussion on the observational evidence in favor of the presence of temperature variations, and conclude that many planetary nebulae show spatial temperature variations that are larger than those predicted by 1D static chemically homogeneous photoionization models. To determine accurate chemical abundances it is necessary to know the cause of these temperature variations and several possibilities are discussed. The importance of this problem is paramount to test the models of stellar evolution of low and intermediate mass stars and of the chemical evolution of galaxies. We conclude that the proper abundances for chemically homogeneous PNe are those derived from recombination lines, while for the two-abundance nebular model the proper heavy element abundances relative to hydrogen are those derived from visual and UV collisionally excited lines adopting the t2 values derived from Te([OIII]) and Te(Balmer) ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0605/0605595v1.pdf"}
{"id": "astro-ph0606016", "abstract": "  We present spectroscopic redshifts for the first 466 X-ray and radio-selected AGN targets in the 2 deg^2 COSMOS field. Spectra were obtained with the IMACS instrument on the Magellan (Baade) telescope, using the nod-and-shuffle technique. We identify a variety of Type 1 and Type 2 AGN, as well as red galaxies with no emission lines. Our redshift yield is 72", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0606/0606016v1.pdf"}
{"id": "astro-ph0606715", "abstract": "  Results are presented on component masses and system angular momenta for over a hundred low-temperature contact binaries. It is found that the secondary components in close binary systems are very similar in mass. Our observational evidence strongly supports the argument that the evolutionary process goes from near-contact binaries to A-type contact binaries, without any need of mass loss from the system. Furthermore, the evolutionary direction of A-type into W-type systems with a simultaneous mass and angular momentum loss is also discussed. The opposite direction of evolution seems to be unlikely, since it requires an increase of the total mass and the angular momentum of the system. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0606/0606715v1.pdf"}
{"id": "astro-ph0607327", "abstract": "  The existing and upcoming multiwavelength data from the Galactic Center suggest a comparative study in order to propose or rule out possible models which would explain the observations. In this paper we consider the X-ray synchrotron and the gamma-ray emission due to Kaluza Klein Dark Matter and define a set of parameters for the shape of the Dark Matter halo which is consistent with the observations. We show that for this class of models the existing Chandra X-ray data is more restrictive than the constraints on very high energy gamma-rays coming from HESS. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0607/0607327v2.pdf"}
{"id": "astro-ph0608350", "abstract": "  Disk galaxies in a cluster of galaxies are moving in hot gas filling the cluster. Generally, they are moving at transonic or supersonic velocities. If ram-pressure stripping is insufficient to destroy the gas disk, the galaxies should be affected by the wind of the surrounding hot gas similar to an airfoil. In this paper, I consider whether the aerodynamic interaction can be strong enough to force a disk galaxy to deviate from the orbit that it would have been in. I find that while the lift force is not effective, the drag force could affect face-on disk galaxies in poor clusters on long timescales. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0608/0608350v1.pdf"}
{"id": "astro-ph0609255", "abstract": "  We have monitored the Neptune-mass exoplanet-hosting M-dwarf Gl 581 with the 1m Swope Telescope at Las Campanas Observatory over two predicted transit epochs. A neutral density filter centered at 550nm was used during the first epoch, yielding 6.33 hours of continuous light curve coverage with an average photometric precision of 1.6 mmags and a cadence of 2.85 min. The second epoch was monitored in B-band over 5.85 hours, with an average photometric precision of 1.2 mmags and 4.28 min cadence. No transits are apparent on either night, indicating that the orbital inclination is less than 88.1 deg for all planets with radius larger than 0.38 R_Nep = 1.48 R_Earth. Because planets of most reasonable interior composition have radii larger than 1.55 R_Earth we place an inclination limit for the system of 88.1 deg. The corresponding minimum mass of Gl 581b remains 0.97 M_Nep = 16.6 M_Earth. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0609/0609255v1.pdf"}
{"id": "astro-ph0609511", "abstract": "  Even quiescent solar prominences may become active and sometimes erupt. These events are occasionally linked to coronal mass ejections. However we know very little about the plasma properties during the activation and eruption processes. We present new computations of the helium line profiles emitted by an eruptive prominence. The prominence is modelled as a plane-parallel slab standing vertically above the solar surface and moving upward as a solid body. The helium spectrum is computed with a non local thermodynamic equilibrium radiative transfer code. The effect of Doppler dimming / brightening is investigated in the resonance lines of He I and He II formed in the EUV, as well as on the He I 10830 A and 5876 A lines. We focus on the line profile properties and the resulting integrated intensities. It is shown that the helium lines are very sensitive to Doppler dimming effects. We also study the effect of frequency redistribution in the formation mechanisms of the resonance lines and find that it is necessary to use partial redistribution in frequency for the resonance lines. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0609/0609511v1.pdf"}
{"id": "astro-ph0609610", "abstract": "  The asymptotic giant branch (AGB) phase of stellar evolution is common to most stars of low and intermediate mass. Most of the carbon and nitrogen in the Universe is produced by AGB stars. The final fate of the AGB envelopes are represented by planetary nebulae (PN). By studying PN abundances and compare them with the yields of stellar evolution is possible to quantify carbon and nitrogen production, and to study cosmic recycling in galactic and Magellanic Cloud populations. In this paper we present the latest results in PN chemical abundance analysis and their implication to the chemical evolution of the galaxy and the Magellanic Clouds, with particular attention to carbon abundance, available only thanks to ultraviolet spectroscopy. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0609/0609610v1.pdf"}
{"id": "astro-ph0610763", "abstract": "  We present the results of a deep-imaging search for wide companions to low-mass stars and brown dwarfs using NSFCam on IRTF. We searched a sample of 132 M7-L8 dwarfs to magnitude limits of J ∼ 20.5 and K ∼ 18.5, corresponding to secondary-primary mass ratios of ∼ 0.5. No companions were found with separations between 2 to 31 (∼40 AU to ∼1000 AU). This null result implies a wide companion frequency below 2.3", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0610/0610763v1.pdf"}
{"id": "astro-ph0611393", "abstract": "  We investigate newtonian description of accreting compact bodies with hard surfaces, including luminosity and selfgravitation of polytropic perfect fluids. This nonlinear integro-differential problem reduces, under appropriate boundary conditions, to an algebraic relation between luminosity and the gas abundance in stationary spherically symmetric flows. There exist, for a given luminosity, asymptotic mass and the asymptotic temperature, two sub-critical solutions that bifurcate from a critical point. They differ by the fluid content and the mass of the compact centre. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0611/0611393v1.pdf"}
{"id": "astro-ph0612061", "abstract": "  The recent discovery of burst oscillations at 1122 Hz in the x-ray transient XTE J1739-285, together with the measurement of the mass of the binary millisecond pulsar PSR J0751+1807 (2.1 +- 0.2 solar masses) can finally allow us to put strong, model-independent observational constraints to the equation of state of compact stars. We show that the measurement of the moment of inertia of PSR J0737+3039A, together with these constraints, could allow to discriminate further the details of the inner structure of neutron stars. Moreover, we show that if XTE J1739-285 is constituted of nucleonic matter, any equation of state allows only a narrow range of very high masses, and this could explain why up to now compact stars spinning faster than a millisecond have been so difficult to detect. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0612/0612061v1.pdf"}
{"id": "astro-ph0612613", "abstract": "  The Baldwin Effect, a negative correlation between emission-line equivalent width and luminosity in active galactic nuclei, is still of interest as a diagnostic of accretion physics nearly thirty years after its discovery. This review examines recent developments in the study of correlations between line and continuum emission in AGNs, as measured both in ensembles and in individual sources. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0612/0612613v1.pdf"}
{"id": "astro-ph0701320", "abstract": "  The observational diversity of “gamma-ray bursts” (GRBs) has been increasing, and the natural inclination is a proliferation of models. We explore the possibility that at least part of this diversity is a consequence of a single basic model for the central engine operating in a massive star of variable mass, differential rotation rate, and mass loss rate. Whatever that central engine may be - and here the collapsar is used as a reference point - it must be capable of generating both a narrowly collimated, highly relativistic jet to make the GRB, and a wide angle, sub-relativistic outflow responsible for exploding the star and making the supernova bright. To some extent, the two components may vary independently, so it is possible to produce a variety of jet energies and supernova luminosities. We explore, in particular, the production of low energy bursts and find a lower limit, ∼10^48 erg s^-1 to the power required for a jet to escape a massive star before that star either explodes or is accreted. Lower energy bursts and and “suffocated” bursts may be particularly prevalent when the metallicity is high, i.e., in the modern universe at low redshift. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0701/0701320v1.pdf"}
{"id": "astro-ph0701655", "abstract": "  We present a grid of 440 spectro-photometric models for simulating spiral and irregular galaxies. They have been consistently calculated with evolutionary synthesis models which use as input the information proceeding from chemical evolution models. The model predictions are spectral energy distributions, brightness and color profiles and radial distributions of spectral absorption stellar indices which are in agreement with observations. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0701/0701655v1.pdf"}
{"id": "astro-ph0702148", "abstract": "  Hierarchical models of galaxy formation now provide a much closer match to observations than they did a few years ago. The progress has been achieved by adjusting the description of baryonic processes such as star formation and supernova/AGN feedback, while leaving the evolution of the underlying dark matter (DM) halos the same. Being most results very sensitive to the input baryonic physics, the ultimate vindication of the hierarchical paradigm should come from observational tests probing more directly the merging history of DM halos rather than the history of star formation. Two questions may start addressing this deeper level: is the predicted halo merging rate consistent with the observed galaxy merging rate? and, are predicted and observed evolution of the galaxy mass function consistent with each other. The current status of these issues is briefly reviewed. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0702/0702148v1.pdf"}
{"id": "astro-ph0703170", "abstract": "  The observations of the bright persistent neutron star low-mass X-ray binary (LMXB) Sco X-1 performed with the Rossi X-ray Timing Explorer (RXTE) show a ∼ 6 Hz normal-branch oscillation (NBO), a ∼ 45 Hz horizontal-branch oscillation (HBO), and twin kHz quasi-periodic oscillations (QPOs) on its normal branch simultaneously. We have found that the fractional amplitude of the HBO corresponding to the NBO phase of high flux is 1.1", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0703/0703170v1.pdf"}
{"id": "astro-ph0703183", "abstract": "  XENON10 is a new direct dark matter detection experiment using liquid xenon as target for weakly interacting, massive particles (WIMPs). A two-phase (liquid/gas) time projection chamber with 15 kg fiducial mass has been installed in a low-background shield at the Gran Sasso Underground Laboratory in July 2006. After initial performance tests with various calibration sources, the science data run started on August 24, 2006. The detector has been running stably since then, and a full analysis of more than 75 live days of WIMP search data is now in progress. We present first results on gamma and neutron calibration runs, as well as a preliminary analysis of a subset of the WIMP search data. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0703/0703183v1.pdf"}
{"id": "astro-ph0703228", "abstract": "  We report the discovery of resolved magnetically split lines in two chemically peculiar stars, the SrEuCr star HD 92499 and the Bp SiCr star HD 157751. From FEROS spectra, we have measured a mean magnetic field modulus of 8.5 kG for HD 92499 and a mean magnetic field modulus of 6.6 kG for HD 157751. Both stars have small projected rotational velocities: v sin i = 3.0 km/s and 8.5 km/s, respectively. Our preliminary abundance analysis reveals ionisation imbalance of rare earths in HD 92499 indicating the abundance pattern typical of rapidly oscillating Ap stars. Cr and Fe are found strongly overabundant in HD 157751. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0703/0703228v1.pdf"}
{"id": "astro-ph0703516", "abstract": "  The halo structure at high Galactic latitudes near both the north and south poles is studied using SDSS and SuperCOSMOS data. For the south cap halo, the archive of the SuperCOSMOS photographic photometry sky survey is used. The coincident source rate between SuperCOSMOS data in B_J band from 16^m.5 to 20^m.5 and SDSS data is about 92", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0703/0703516v2.pdf"}
{"id": "astro-ph9412038", "abstract": "  For massive black hole binaries produced in galactic mergers, we examine the possibility of inspiral induced by interaction with field stars. We model the evolution of such binaries for a range of galaxy core and binary parameters, using numerical results from the literature to compute the binary's energy and angular momentum loss rates due to stellar encounters and including the effect of back-action on the field stars. We find that only a small fraction of binary systems can merge within a Hubble time via unassisted stellar dynamics. External perturbations may, however, cause efficient inspiral. Averaging over a population of central black holes and galaxy mergers, we compute the expected background of gravitational radiation with periods Pw   1-10 yr. Comparison with sensitivities from millisecond pulsar timing suggests that the strongest sources may be detectable with modest improvements to present experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9412/9412038v3.pdf"}
{"id": "astro-ph9601166", "abstract": "  We consider the hypothesis that the formation of elliptical galaxies includes a phase in which star formation is mostly restricted to massive stars, with the bias towards high mass stars increasing with elliptical galaxy mass. The mass fraction of stars in this top-heavy mode of star formation is constrained by requiring the resulting stellar remnants to account for the observed increase in the mass-to-light ratio of ellipticals with increasing galaxy mass. We then consider the implications of this population of massive stars for the intracluster medium and the extragalactic background at various wavelengths. The mass and abundance ratios of metals produced by our proposed population of massive stars are consistent with the observations of the mass and abundance ratios of metals in the hot gas of galaxy clusters for most of the standard range of IMF slopes and SN II yields. The predicted energy density produced by this stellar population approaches current limits on the extragalactic background at both optical wavelengths, into which the ultraviolet radiation of the massive stars is likely to be redshifted, and far-infared wavelengths, at which starlight reprocessed by dust associated with the starburst will be observed. In either case, the background is predicted to be significantly clustered since massive ellipticals are clustered. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9601/9601166v2.pdf"}
{"id": "astro-ph9605195", "abstract": "  We investigate here the origin of the gas observed in extended emission line regions surrounding AGNs. We use the technique of calcium depletion as a test to prove or disprove the existence of dust in such a gas in order to discriminate between two main theories: (1) a cooling process from a hotter X-ray emitting phase surrounding the galaxy, (2) merging or tidal interaction between two or more components. We have obtained long slit spectroscopy of a sample of objects representative of different galaxy types although our main interest focus on radio galaxies. The spectral range was set to always includethe [CaII]λλ7291,7324 doublet. The faintness or absence of such lines is interpreted as due to the depletion of calcium onto the dust grains and, therefore, is a proof of the existence of dust mixed with the gas in the EELRs. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9605/9605195v1.pdf"}
{"id": "astro-ph9608017", "abstract": "  We investigate a distortion in redshift-space which causes galaxies to appear to lie in walls concentric about the observer, forming a rough bull's-eye pattern. We simulate what an observer would see in a thin slice of redshift-space, including a magnitude limit and constant slice angle. The result is an enhanced ring of galaxies encircling the observer at a distance roughly corresponding to the peak of the selection function. This ring is an artificial enhancement of weak features in real-space. This may explain visually prominent features such as the “Great Wall” and periodicity found in deep narrow fields. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9608/9608017v2.pdf"}
{"id": "astro-ph9609111", "abstract": "  A brief summary of properties of the contact binaries is presented, with the goal to stress the unsolved problems of their formation and evolution as well as their potential contribution to studies of Galactic stellar populations. The first results from the OGLE survey, where the contact binaries contribute a full two thirds among 933 eclipsing binary stars, are presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9609/9609111v1.pdf"}
{"id": "astro-ph9611215", "abstract": "  By proposing a statistic for the detection of secondary (Doppler) peaks in the CMBR power spectrum, the significance level at which such peaks may be detected are computed for a large range of model CMBR experiments. In particular, we investigate experimental design features required to distinguish between competing cosmological theories, such as cosmic strings and inflation, by establishing whether or not secondary peaks are present in the CMBR power spectrum. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9611/9611215v1.pdf"}
{"id": "astro-ph9612094", "abstract": "  In this paper I investigate the γ-ray spectra of AGN by summing up the intensity and the power-law fit statistic of Quasars and OVV's and BL Lac's separately. The spectrum of the average AGN is softer than that of the extragalactic γ-ray background. It may be that BL Lac's, of which the average has a harder spectrum than Quasars, make up the bulk of the extragalactic background. We also find cut-offs both at low and at high energies in the spectra of Quasars and OVV's, however only at the time of γ-ray outbursts. While the cut-off at high energies may have something to do with opacity, the cut-off at low energies may be taken as indication that the γ-ray emission of Quasars is not a one component spectrum. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9612/9612094v1.pdf"}
{"id": "astro-ph9706127", "abstract": "  We have analyzed new and archival IUE observations of narrow-line Seyfert 1 galaxies (NLS1) in order to revise the ultraviolet (UV) properties of this sub-group of Active Galactic Nuclei (AGN). We have found broad wings in the strongest UV emission lines, ruling out the hypothesis that there is no broad line emission region in this type of objects. Since the similarities in spectral energy distributions from the far-infrared (FIR) to the soft X rays in both narrow-line and broad-line Seyfert 1 galaxies do not suggest that the nuclei of NLS1 are hidden from a direct view, we discuss the possibility that the line emitting material in NLS1 is optically thin. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9706/9706127v1.pdf"}
{"id": "astro-ph9706188", "abstract": "  We present 0.1-10 keV observations of Her X-1 obtained with the Low-Energy Spectrometer Concentrator instrument onboard the BeppoSAX satellite during the main on-state of the 35 day cycle. We confirm the existence of an intense 0.093 keV blackbody component and a broad emission feature at 0.94 keV. The pulse phase dependence of these components is similar, suggesting a common origin. This is most likely fluorescent excitation of moderately ionized (ξ∼10–100) material located at the inner edge of the accretion disk. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9706/9706188v1.pdf"}
{"id": "astro-ph9708050", "abstract": "  We have selected quasars with X-ray colors suggestive of a low energy cut-off, from the ROSAT PSPC pointed archive. We examine the radio and optical properties of these 13 quasars. Five out of the seven quasars with good optical spectra show associated optical absorption lines, with two having high delta-v candidate systems. Two other cut-off quasars show reddening associated with the quasar. We conclude that absorption is highly likely to be the cause of the X-ray cut-offs, and that the absorbing material associated with the quasars, not intervening along the line-of-sight. The suggestion that Gigahertz Peaked Sources are associated with X-ray cut-offs remains unclear with this expanded sample. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9708/9708050v1.pdf"}
{"id": "astro-ph9711311", "abstract": "  We use a Monte Carlo technique and assumed spatial distributions of dust and supernova (SN) progenitors in a simple model of a characteristic SN–producing disk galaxy to explore the effects of extinction on the radial distributions of SN properties in their parent galaxies. The model extinction distributions and projected radial number distributions are presented for various SN types. Even though the model has no core-collapse SNe within three kpc of the center, a considerable fraction of the core-collapse SNe are projected into the inner regions of inclined parent galaxies owing to their small vertical scale height. The model predicts that because of extinction, SNe projected into the central regions should on average appear dimmer and have a much larger magnitude scatter than those in the outer regions. In particular, the model predicts a strong deficit of bright core-collapse events inside a projected radius of a few kpc. Such a deficit is found to be present in the observations. It is a natural consequence of the characteristic spatial distributions of dust and core-collapse SNe in galaxies, and it leads us to offer an alternative to the conventional interpretation of the Shaw effect. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9711/9711311v1.pdf"}
{"id": "astro-ph9712007", "abstract": "  Using a novel two-dimensional coordinate system, we have derived a particularly simple way to express the redshift distortions in galaxy redshift surveys with arbitrary geometry in closed form. This method provides an almost ideal way to measure the value of β=Ω_0^0.6/b in wide area surveys, since all pairs in the survey can be used for the analysis. In the limit of small angles, this result straightforwardly reduces to the plane-parallel approximation. This expansion can also be used together with more sophisticated methods such as for the calculation of Karhunen-Loeve eigenvectors in redshift space for an arbitrary survey geometry. Therefore, these results should provide for more precise methods in which to measure the large scale power spectrum and the value of β simultaneously. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9712/9712007v1.pdf"}
{"id": "astro-ph9802224", "abstract": "  I review recent studies about the gravitational potential and stellar dynamics of M87 in particular, and the dynamics of the stars in the presence of a super-massive central black hole, in general.   At large radii, investigations of both the X-ray emitting gas and the velocity distribution of globular clusters indicate the presence of large amounts of non-luminous matter, possibly belonging to the inner parts of the Virgo cluster.   At small radii, there is no evidence from the stellar kinematics, at most a hint, for the existence of a central point mass, whereas the gas dynamics reveal the presence of a highly concentrated mass in the centre of M87, possibly a super-massive black hole (BH). Given the existence of such a central mass, the stellar kinematics indicate a strong tangential anisotropy of the stellar motion inside a few arcseconds. The implications of this result for the evolution and formation history of M87 and its central BH are discussed. I also discuss in more general terms the structural changes that a highly concentrated central mass can induce in its parent galaxy. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9802/9802224v1.pdf"}
{"id": "astro-ph9803076", "abstract": "  A gravitational lens model is presented for the newly discovered 10-image system B1933+503. The underlying object, revealed by modeling, is a triple radio source on the scale of a couple of hundred mas that is well-aligned along the line of sight with a foreground and somewhat flattened lensing galaxy, whose orientation and location match that of an observed galaxy, known to be at a redshift of 0.755. Uncertainties in the modeling are obtained by a Monte Carlo exercise. Observational tests of the lens model are proposed, and the time delays between various pairs of images are determined as the core of the source is known to be significantly variable. Future observations of the lens hold the key to using B1933+503 to constrain Hubble's Constant. Despite the absence of a source redshift, the system's utility as a probe of the lens galaxy's structure is unparalleled as it provides a surfeit of easily identifiable constraints for modeling the system. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9803/9803076v2.pdf"}
{"id": "astro-ph9808080", "abstract": "  In the early nineties several teams started large scale systematic surveys of the Magellanic Clouds and the Galactic Bulge to search for microlensing effects. As a by product, these groups have created enormous time-series databases of photometric measurements of stars with a temporal sampling duration and accuracy which are unprecedented. They provide the opportunity to test the accuracy of primary distance indicators, such as Cepheids, RRLyrae stars, the detached eclipsing binaries, or the luminosity of the red clump. We will review the contribution of the microlensing surveys to the understanding of the physics of the primary distance indicators, recent differential studies and direct distance determinations to the Magellanic Clouds and the Galactic Bulge. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9808/9808080v1.pdf"}
{"id": "astro-ph9808288", "abstract": "  If the background universe is observed through a significant amount of diffusely distributed foreground dust, then studies at optical wavelengths may be severely biased. Previous studies investigating effects of foreground dust on background sources assumed the dust to be “compactly” distributed, ie. on scales comparable to the visible extent of normal galaxies. We show however that diffuse dust is more effective at obscuring background sources. Galaxy clusters are a likely location for “large-scale” diffusely distributed dust, and its effect on the counts of background sources is explored. We also explore the implications of a hypothesised diffuse intergalactic dust component uniformly distributed to high redshift with comoving mass density equal to that associated with local galaxies. In this case, we predict a deficit in background sources about three times greater than that found in previous studies. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9808/9808288v1.pdf"}
{"id": "astro-ph9809106", "abstract": "  We obtain lithium abundances for G and K stars in Blanco 1, an open cluster with an age similar to, or slightly younger than, the Pleiades. We critically examine previous spectroscopic abundance analyses of Blanco 1 and conclude that while there were flaws in earlier work, it is likely that Blanco 1 is close in overall metallicity to the older Hyades cluster and more metal-rich than the Pleiades. However, we find Blanco 1 has Li abundances and rotation rates similar to the Pleiades, contradicting predictions from standard stellar evolution models, in which convective pre-main sequence (PMS) Li depletion should increase rapidly with metallicity. If the high metallicity of Blanco 1 is subsequently confirmed, our observations imply (1) that a currently unknown mechanism severely inhibits PMS Li depletion, (2) that additional non-standard mixing modes, such as those driven by rotation and angular momentum loss, are then responsible for main sequence Li depletion between the ages of Blanco 1 and the Hyades, and (3) that in clusters younger than the Hyades, metallicity plays only a minor role in determining the amount of Li depletion among G and K stars. These conclusions suggest that Li abundance remains a useful age indicator among young (less than 700 Myr) stars even when metallicities are unknown. If non-standard mixing is effective in Population I stars, the primordial Li abundance could be significantly larger than present day Population II Li abundances, due to prior Li depletion. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9809/9809106v2.pdf"}
{"id": "astro-ph9809125", "abstract": "  We investigate the growth of tidal instabilities in accretion discs in a binary star potential, using three dimensional numerical simulations. As expected from analytic work, the disc is prone to an eccentric instability provided that it is large enough to extend to the 3:1 resonance. The eccentric disc leads to positive superhumps in the light curve. It has been proposed that negative superhumps might arise from a tilted disc, but we find no evidence that the companion gravitational tilt instability can grow fast enough in a fluid disc to create a measurable inclination. The origin of negative superhumps in the light curves of cataclysmic variables remains a puzzle. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9809/9809125v1.pdf"}
{"id": "astro-ph9809387", "abstract": "  This paper addresses the issue of how best to correct astronomical data for the wavelength-dependent effects of Galactic interstellar extinction. The main general features of extinction from the IR through the UV are reviewed, along with the nature of observed spatial variations. The enormous range of extinction properties found in the Galaxy, particularly in the UV spectral region, is illustrated. Fortunately, there are some tight constraints on the wavelength dependence of extinction and some general correlations between extinction curve shape and interstellar environment. These relationships provide some guidance for correcting data for the effects of extinction. Several strategies for dereddening are discussed along with estimates of the uncertainties inherent in each method. In the Appendix, a new derivation of the wavelength dependence of an average Galactic extinction curve from the IR through the UV is presented, along with a new estimate of how this extinction law varies with the parameter R = A(V)/E(B-V). These curves represent the true monochromatic wavelength dependence of extinction and, as such, are suitable for dereddening IR–UV spectrophotometric data of any resolution, and can be used to derive extinction relations for any photometry system. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9809/9809387v1.pdf"}
{"id": "astro-ph9810370", "abstract": "  We present imaging polarimetry of the extremely luminous, redshift 2.3 IRAS source FSC10214+4724. The observations were obtained with HST's Faint Object Camera in the F437M filter, which is free of strong emission lines. The 0.7 arcsec long arc is unresolved to 0.04 arcsec FWHM in the transverse direction, and has an integrated polarization of 28 +/- 3 percent, in good agreement with ground-based observations. The polarization position angle varies along the arc by up to 35 deg. The overall position angle is 62 +/- 3 deg east of north. No counterimage is detected to B = 27.5 mag (3σ), giving an observed arc to counterimage flux ratio greater than 250, considerably greater than the flux ratio of 100 measured previously in the I-band. This implies that the configuration of the object in the source plane at the B-band is different from that at I-band, and/or that the lensing galaxy is dusty. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9810/9810370v1.pdf"}
{"id": "astro-ph9811030", "abstract": "  A number of emission and absorption features are expected to be visible in high energy resolution X-ray spectra of type 1 AGN with ionized gas along the line of sight (so called \"warm absorbers\"). Emission strongly depends on the geometrical configuration of the gas, while absorption along the line of sight does not. Absorption features include photoelectric absorption K and L edges along with many strong Kα, Kβ and L resonance absorption lines from the most abundant elements. We present detailed simulations of our “photoelectric + resonant absorption” model with the high energy resolution gratings and calorimeters of AXAF, XMM and Constellation-X, and discuss the relevant physics which can be addressed with the new generation of X-ray spectrometers. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9811/9811030v1.pdf"}
{"id": "astro-ph9811057", "abstract": "  We employ a variety of numerical simulations in the local shearing box system to investigate in greater depth the local hydrodynamic stability of Keplerian differential rotation. In particular we explore the relationship of Keplerian shear to the nonlinear instabilities known to exist in simple Cartesian shear. The Coriolis force is the source of linear stabilization in differential rotation. We exploit the formal equivalence of constant angular momentum flows and simple Cartesian shear to examine the transition from stability to nonlinear instability. The manifestation of nonlinear instability in shear flows is known to be sensitive to initial perturbation and to the amount of viscosity; marginally (linearly) stable differentially rotating flows exhibit this same sensitivity. Keplerian systems, however, are completely stable; the strength of the stabilizing Coriolis force easily overwhelms any destabilizing nonlinear effects. In fact, nonlinear effects speed the decay of applied turbulence by producing a rapid cascade of energy to high wavenumbers where dissipation occurs. Our conclusions are tested with grid resolution experiments and by comparison with results from a code that employs an alternative numerical algorithm. The properties of hydrodynamic differential rotation are contrasted with magnetohydrodynamic differential rotation. The kinetic stress couples to the vorticity which limits turbulence, while the magnetic stress couples to the shear which promotes turbulence. Thus magnetohydrodynamic turbulence is uniquely capable of acting as a turbulent angular momentum transport mechanism in disks. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9811/9811057v1.pdf"}
{"id": "astro-ph9811326", "abstract": "  In the ROSAT Bright Survey (RBS) we have almost completely optically identified the brightest  2000 high-galactic latitude sources from the ROSAT All-Sky Survey Bright Source Catalogue (1RXS). A small number of sources has empty X-ray error circles on optical images. ROSAT HRI follow-up observations of RBS1223 (=1RXS J130848.6+212708), a soft object with extreme X-ray to optical flux ratio, have confirmed a relatively bright X-ray source, whose position could be determined to an accuracy of 1.6 arcsec (90", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9811/9811326v1.pdf"}
{"id": "astro-ph9812099", "abstract": "  Coronal Mass Ejections continuously drag closed magnetic field lines away from the Sun, adding new flux to the interplanetary magnetic field (IMF). We propose that the outward-moving blobs that have been observed in helmet streamers are evidence of ongoing, small-scale reconnection in streamer current sheets, which may play an important role in the prevention of an indefinite buildup of the IMF. Reconnection between two open field lines from both sides of a streamer current sheet creates a new closed field line, which becomes part of the helmet, and a disconnected field line, which moves outward. The blobs are formed by plasma from the streamer that is swept up in the trough of the outward moving field line. We show that this mechanism is supported by observations from SOHO/LASCO. Additionally, we propose a thorough statistical study to quantify the contribution of blob formation to the reduction of the IMF, and indicate how this mechanism may be verified by observations with SOHO/UVCS and the proposed NASA STEREO and ESA Polar Orbiter missions. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9812/9812099v1.pdf"}
{"id": "astro-ph9812466", "abstract": "  The degree of linear polarization has recently been found to show wide random variations over the solar disk. These variations are presumably at least partly due to fluctuations in the flux density of turbulent photospheric magnetic fields and associated variations in the degree of Hanle depolarization. In order to understand the origin of such large scale fluctuations of the turbulent magnetic flux density we develop a phenomenological model to calculate the spatial Fourier spectrum of the fluctuations of turbulent magnetic fields in the solar photosphere and convective zone. It is found that if the model parameters are fitted to turbulence closure models and numerical experiments the characteristic scale of the fluctuations is by about an order of magnitude larger than the turbulence scale (the scale of the granulation), owing to the more effective quenching of small-scale fluctuations by turbulent diffusion. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9812/9812466v1.pdf"}
{"id": "astro-ph9903365", "abstract": "  A new approach in the gravitational wave experiment is considered. In addition to the old method of searching for coincident reactions of two separated gravitational antennae it was proposed to seek perturbations of the gravitational detector noise background correlated with astrophysical events such as neutrino and gamma ray bursts which can be relaibly registered by correspondent sensors. A general algorithm for this approach is developed. Its efficiency is demonstrated in reanalysis of the old data concerning the phenomenon of neutrino-gravity correlation registered during of SN1987A explosion. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9903/9903365v1.pdf"}
{"id": "astro-ph9903390", "abstract": "  The results of VLBI observations of the quasar 3C273, obtained during a multi-frequency campaign in late 1992 in the radio, millimeter and X-ray bands are presented and discussed. The VLBI observations were made at 22 GHz with a Global Array and at 43 GHz with the Very Long Baseline Array. Hybrid maps and modelfits were made in order to look for any short time scale structural variations of the inner part of the radio jet. In 42 days 3C273 was observed 5 times at roughly 10 day intervals. The jet structure did not show dramatic changes in that period. However, we were able to follow the changes in the positions of the components along the first 2 mas of the jet with respect to the core. The resolution achieved by these observations allows the decomposition of the apparent velocity vector of each component into two orthogonal directions. We find evidence of reverse motion for a component along the jet. The jet starts wiggling well inside the first parsec from the core. The spatial period of the quasi-sinusoidal oscillating jet path about the jet major axis was derived for distances between 2 and 8 mas from the core. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9903/9903390v1.pdf"}
{"id": "astro-ph9903407", "abstract": "  Compact object mergers are one of the currently favored models for the origin of GRBs. The discovery of optical afterglows and identification of the nearest, presumably host, galaxies allows the analysis of the distribution of burst sites with respect to these galaxies. Using a model of stellar binary evolution we synthesize a population of compact binary systems which merge within the Hubble time. We include the kicks in the supernovae explosions and calculate orbits of these binaries in galactic gravitational potentials. We present the resulting distribution of merger sites and discuss the results in the framework of the observed GRB afterglows. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9903/9903407v1.pdf"}
{"id": "astro-ph9904391", "abstract": "  Numerous X-ray bursts show strong oscillations in their flux at several hundred Hz as revealed by RXTE. Analyzing one such oscillation from the X-ray binary Aql X-1, I find that low energy photons (3.5-5.7 keV) lag high energy photons (>5.7 keV) by approximately 1 radian. The oscillations are thought to be produced by hot spots on the spinning neutron star. The lags can then be explained by a Doppler shifting of emission from the hot spots; higher energy photons being emitted earlier in the spin phase as the spot approaches the observer. A quantitative test of this simple model shows a remarkable agreement with the data. Similar low energy lags have been measured in kilohertz quasi-periodic oscillations and in the accreting millisecond pulsar SAX J1808.4-3658. A Doppler delay mechanism may be at work there as well. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9904/9904391v1.pdf"}
{"id": "astro-ph9907307", "abstract": "  This chapter discusses Galactic dust and how its thermal emission confuses CMBR measurements. Interstellar dust grains are composed of many differing species, and observational evidence has only begun to disentagle their composition and sizes. Fortunately, their far-IR/millimeter emission is less complex. We describe how a very simple two-species model can describe the emission at 200 < nu < 3000 GHz to high precision. At lower frequencies, other non-thermal processes may dominate the emission from dust. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9907/9907307v1.pdf"}
{"id": "astro-ph9907409", "abstract": "  Two hypothesized solutions of the mass discrepancy problem are cold dark matter (CDM) and modified Newtonian dynamics (MOND). The virtues and vices of these very different hypotheses are largely disjoint, making the process of distinguishing between them very dependent on how we weigh disparate lines of evidence. One clear difference is the nature of the principal mass constituent of the universe (CDM or baryons). This difference in the baryon fraction (f_b ≈ 0.1 vs. 1) should leave a distinctive signature in the spectrum of fluctuations in the cosmic microwave background. Here I discuss some of the signatures which should be detectable in the near future. The most promising appears to be the ratio of the amplitudes of the first two peaks relative to the intervening trough. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9907/9907409v1.pdf"}
{"id": "astro-ph9908279", "abstract": "  We examine the effects of a relativistic wind on the spin down of a neutron star and apply our results to the study of Soft Gamma Repeaters (SGRs), thought to be neutron stars with magnetic fields > 10^14 G. We derive a spin-down formula that includes torques from both dipole radiation and episodic or continuous particle winds. We find that if SGR1806-20 puts out a continuous particle wind of 10^37 erg s^-1, then the pulsar age is consistent with that of the surrounding supernova remnant, but the derived surface dipole magnetic field is only 3 ×10^13 G, in the range of normal radio pulsars. If instead, the particle wind flows are episodic with small duty cycle, then the observed period derivatives imply magnetar-strength fields, while still allowing characteristic ages within a factor of two of the estimated supernova remnant age. Close monitoring of the periods of SGRs will be able to establish or place limits on the wind duty cycle and thus the magnetic field and age of the neutron star. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9908/9908279v2.pdf"}
{"id": "astro-ph9909028", "abstract": "  We report on one year of photometric monitoring of the ultraluminous BAL quasar APM 08279+5255. The temporal sampling reveals that this gravitationally lensed system has brightened by  0.2 mag in 100 days. Two potential causes present themselves; either the variability is intrinsic to the quasar, or it is the result of microlensing by stars in a foreground system. The data is consistent with both hypotheses and further monitoring is required before either case can be conclusively confirmed. We demonstrate, however, that gravitational microlensing can not play a dominant role in explaining the phenomenal properties exhibited by APM 08279+5255. The identification of intrinsic variability, coupled with the simple gravitational lensing configuration, would suggest that APM 08279+5255 is a potential golden lens from which the cosmological parameters can be derived and is worthy of a monitoring program at high spatial resolution. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9909/9909028v1.pdf"}
{"id": "astro-ph9909170", "abstract": "  We propose and investigate a new formation mechanism for globular clusters in which they form within molecular clouds that are formed in the shocked regions created by galactic winds driven by successive supernova explosions shortly after the initial burst of massive star formation in the galactic centers. The globular clusters have a radial distribution that is more extended than that of the stars because the clusters form as pressure-confined condensations in a shell that is moving outward radially at high velocity. In addition the model is consistent with existing observations of other global properties of globular clusters, as far as comparisons can be made. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9909/9909170v1.pdf"}
{"id": "astro-ph9911298", "abstract": "  Tensor-scalar theory of gravity allows the generation of gravitational waves from astrophysical sources, like Supernovæ, even in the spherical case. That motivated us to study the collapse of a degenerate stellar core, within tensor-scalar gravity, leading to the formation of a neutron star through a bounce and the formation of a shock. We discuss in this paper the effects of the scalar field on the evolution of the system, as well as the appearance of strong non-perturbative effects of this scalar field (the so-called “spontaneous scalarization”). As a main result, we describe the resulting gravitational monopolar radiation (form and amplitude) and discuss the possibility of its detection by the gravitational detectors currently under construction, taking into account the existing constraints on the scalar field.   From the numerical point of view it is worthy to point out that we have developed a combined code which uses pseudo-spectral methods, for the evolution of the scalar field, and High Resolution Shock-Capturing schemes, for the evolution of the hydrodynamical system. Although this code has been used to integrate the field equations of that theory of gravity, in the spherically symmetric case, a by-product of the present work is to gain experience for an ulterior extension to multidimensional problems in Numerical Relativity of such numerical strategy. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9911/9911298v1.pdf"}
{"id": "astro-ph9912361", "abstract": "  Many thermonuclear X-ray bursts exhibit brightness oscillations. The brightness oscillations are thought to be due to the combined effects of non-uniform nuclear burning and rotation of the neutron star. The waveforms of the oscillations contain information about the size and number of burning regions. They also contain substantial information about the mass and radius of the star, and hence about strong gravity and the equation of state of matter at supranuclear densities. We have written general relativistic ray-tracing codes that compute the waveforms and spectra of rotating hot spots as a function of photon energy. Using these codes, we survey the effect on the oscillation waveform and amplitude of parameters such as the compactness of the star, the spot size, the surface rotation velocity, and whether there are one or two spots. We also fit phase lag versus photon energy curves to data from the millisecond X-ray pulsar, SAX J1808–3658. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9912/9912361v1.pdf"}
{"id": "chao-dyn9511007", "abstract": "  The new phenomenon of semiquantum chaos is analyzed in a classically regular double-well oscillator model. Here it arises from a doubling of the number of effectively classical degrees of freedom, which are nonlinearly coupled in a Gaussian variational approximation (TDHF) to full quantum mechanics. The resulting first-order nondissipative autonomous flow system shows energy dependent transitions between regular behavior and semiquantum chaos, which we monitor by Poincaré sections and a suitable frequency correlation function related to the density matrix. We discuss the general importance of this new form of deterministic chaos and point out the necessity to study open (dissipative) quantum systems, in order to observe it experimentally. ", "pdf_url": "gs://arxiv-dataset/arxiv/chao-dyn/pdf/9511/9511007v2.pdf"}
{"id": "chao-dyn9703015", "abstract": "  We present an analytical scheme, easily implemented numerically, to generate synthetic Gaussian turbulent flows by using a linear Langevin equation, where the noise term acts as a stochastic stirring force. The characteristic parameters of the velocity field are well introduced, in particular the kinematic viscosity and the spectrum of energy. As an application, the diffusion of a passive scalar is studied for two different energy spectra. Numerical results are compared favorably with analytical calculations. ", "pdf_url": "gs://arxiv-dataset/arxiv/chao-dyn/pdf/9703/9703015v1.pdf"}
{"id": "cmp-lg9706013", "abstract": "  Semantic knowledge can be a great asset to natural language processing systems, but it is usually hand-coded for each application. Although some semantic information is available in general-purpose knowledge bases such as WordNet and Cyc, many applications require domain-specific lexicons that represent words and categories for a particular topic. In this paper, we present a corpus-based method that can be used to build semantic lexicons for specific categories. The input to the system is a small set of seed words for a category and a representative text corpus. The output is a ranked list of words that are associated with the category. A user then reviews the top-ranked words and decides which ones should be entered in the semantic lexicon. In experiments with five categories, users typically found about 60 words per category in 10-15 minutes to build a core semantic lexicon. ", "pdf_url": "gs://arxiv-dataset/arxiv/cmp-lg/pdf/9706/9706013v1.pdf"}
{"id": "cond-mat0002367", "abstract": "  A numerical algorithm based on the finite element methods has been developed to accurately determine the shape of the boundary of a domain containing “boojum” textures. Within the context of the simple model we adopt, the effects of both bulk elastic anisotropy and line-tension anisotropy on the domain boundary can be examined. It is found that line-tension anisotropy must be present in order to account for domains with protruding features. Both elastic anisotropy and anisotropic line-tension can result in domains with indentations. The numerical algorithm has been extended to investigate the problem of a bubble in extended region ordered phase. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0002/0002367v1.pdf"}
{"id": "cond-mat0003018", "abstract": "  In this paper, a delocalization-localization transition within the superconducting state is explored. The symmetries of the Bogoliubov deGennes   Hamiltonian endow the two associated superconducting phases - the thermal metal and the thermal insulator-, and the critical point between them with properties that are in stark contrast with analogous phases in normal systems. Here, for systems preserving spin rotational invariance and time reversal symmetry in three dimensions, the transition is shown to be of a different universality class from its normal partner by extracting and comparing the localization length exponent. The density of states, which may be regarded as the 'order parameter' for the field theory describing the superconducting system, is studied for its unusual properties about criticality. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0003/0003018v2.pdf"}
{"id": "cond-mat0003394", "abstract": "  An earlier one-dimensional lattice model of hydrophobic attraction is extended to two and three dimensions and studied by Monte Carlo simulation. The solvent-mediated contribution to the potential of mean force between hydrophobic solute molecules and the solubility of the solute are determined. As in the earlier model, an inverse relation is observed between the strength and range of the hydrophobic attraction. The mean force no longer varies monotonically with distance, as it does in one dimension, but has some oscillations, reflecting the greater geometrical complexity of the lattice in the higher dimensions. In addition to the strong attraction at short distances, there is now also a local minimum in the potential of depth about kT at a distance of three lattice spacings in two dimensions and one of depth about 2kT at a distance of two lattice spacings in three dimensions. The solubility of the solute is found to decrease with increasing temperature at low temperatures, which is another signature of the hydrophobic effect and also agrees with what had been found in the one-dimensional model. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0003/0003394v1.pdf"}
{"id": "cond-mat0006447", "abstract": "  Spontaneous spreading of a polymer drop on a solid substrate can be forced by a low pressure gaseous discharge applied between the cathode that supports the drop and a remote electrode. We prone to think that the driving force for this plasma driven spreading is the spatial distribution of the electric field at the cathode. Two distinct effects caused by the gas plasma are observed: spreading of a thin film and shrinking of the rest liquid into a spherical drop upon its own film. The last effect, never reported before, can be addressed to the effect of the electric stresses developed in the ionic double layer formed at the polymer/plasma interface. The spreading front displays a fingering instability similar to that observed earlier in various experimental conditions <cit.>. Theoretical analysis shows that the Marangoni stress acts as the driving force for the finger growth. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0006/0006447v1.pdf"}
{"id": "cond-mat0009168", "abstract": "  The phase-separation kinetics of binary fluids in shear flow is studied numerically in the framework of the continuum convection-diffusion equation based on a Ginzburg-Landau free energy. Simulations are carried out for different temperatures both in d=2 and in d=3. Our results confirm the qualitative picture put forward by the large-N limit equations studied in <cit.>. In particular, the structure factor is characterized by the presence of four peaks whose relative oscillations give rise to a periodic modulation of the behavior of the rheological indicators and of the average domains sizes. This peculiar pattern of the structure factor corresponds to the presence of domains with two characteristic thicknesses whose relative abundance changes with time. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0009/0009168v1.pdf"}
{"id": "cond-mat0011053", "abstract": "  Energies and wave functions are calculated for d-wave quasiparticles in the mixed state using the formalism of Franz and Tesanovic for the low-lying energy levels. The accuracy of the plane-wave expansion is explored by comparing approximate to exact results for a simplified one-dimensional problem, and the convergence of the plane- wave expansion to the two-dimensional case is studied. The results are used to calculate the low-energy tunneling density of states and the low-temperature specific heat, and these theoretical results are compared to semiclassical treatments and to the available data. Implications for the muon spin resonance measurements of vortex core size are also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0011/0011053v2.pdf"}
{"id": "cond-mat0012279", "abstract": "  The magnetic interaction of a pair of bound magnetic polarons (BMP) in diluted magnetic semiconductors (DMS) is analyzed via a generalized Hubbard-type Hamiltonian for two carriers in the presence of effective magnetic fields arising from the magnetic polarization of their respective polarons. For the case where the magnetic fields at the two sites have equal magnitude but are allowed to have arbitrary directions, it is shown that the energy of the two polarons is minimized for a ferromagnetic configuration of the carrier spins (in contrast to the case of hydrogenic centers in nonmagnetic semiconductors) if polaron fields are strong enough. A modified Heisenberg-type Hamiltonian is constructed to describe the low energy states of the resulting system. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0012/0012279v1.pdf"}
{"id": "cond-mat0101361", "abstract": "  We have applied the Ewald-Kornfeld formulation to a tetragonal lattice of point dipoles, in an attempt to examine the effects of geometric anisotropy on the local field distribution. The various problems encountered in the computation of the conditionally convergent summation of the near field are addressed and the methods of overcoming them are discussed. The results show that the geometric anisotropy has a significant impact on the local field distribution. The change in the local field can lead to a generalized Clausius-Mossotti equation for the anisotropic case. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0101/0101361v1.pdf"}
{"id": "cond-mat0102348", "abstract": "  We have analyzed DNA sequences of known genes from 16 yeast chromosomes (Saccharomyces cerevisiae) in terms of oligonucleotides. We have noticed that the relative abundances of oligonucleotide usage in the genome follow a long-tail Levy-like distribution. We have observed that long genes often use strongly over-represented and under-represented nucleotides, whereas it was not the case for the short genes (shorter than 300 nucleotides) under consideration. If selection on the extremely over-represented/under-represented oligonucleotides was strong, long genes would be more affected by spontaneous mutations than short ones. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0102/0102348v1.pdf"}
{"id": "cond-mat0103092", "abstract": "  A computer model of the feed-forward neural network with the hidden layer is developed to reconstruct physical field investigated by the fiber-optic measuring system. The Gaussian distributions of some physical quantity are selected as learning patterns. Neural network is learned by error back-propagation using the conjugate gradient and coordinate descent minimization of deviation. Learned neural network reconstructs the two-dimensional scalar physical field with distribution having one or two Gaussian peaks. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0103/0103092v1.pdf"}
{"id": "cond-mat0103410", "abstract": "  We calculate the effect of an inhomogeneous magnetic field, which is invariably present in an experimental environment, on the exchange energy of a double quantum dot artificial molecule, projected to be used as a 2-qubit quantum gate in the proposed quantum dot quantum computer. We use two different theoretical methods to calculate the Hilbert space structure in the presence of the inhomogeneous field: the Heitler-London method which is carried out analytically and the molecular orbital method which is done computationally. Within these approximations we show that the exchange energy J changes slowly when the coupled dots are subject to a magnetic field with a wide range of inhomogeneity, suggesting swap operations can be performed in such an environment as long as quantum error correction is applied to account for the Zeeman term. We also point out the quantum interference nature of this slow variation in exchange. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0103/0103410v2.pdf"}
{"id": "cond-mat0104339", "abstract": "  In this work we incorporate some real-system effects into the theory of orientational phase transitions under shear flow (M. E. Cates and S. T. Milner, Phys. Rev. Lett. v.62, p.1856 (1989) and G. H. Fredrickson, J. Rheol. v.38, p.1045 (1994)). In particular, we study the influence of the shear-cell boundaries on the orientation of the lamellar phase. We predict that at low shear rates the parallel orientation appears to be stable. We show that there is a critical value of the shear rate at which the parallel orientation loses its stability and the perpendicular one appears immediately below the spinodal. We associate this transition with a crossover from the fluctuation to the mean-field behaviour. At lower temperatures the stability of the parallel orientation is restored. We find that the region of stability of the perpendicular orientation rapidly decreases as shear rate increases. This behaviour might be misinterpreted as an additional perpendicular to parallel transition recently discussed in literature. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0104/0104339v1.pdf"}
{"id": "cond-mat0106456", "abstract": "  We study the effect of electron-electron backscattering interactions on spin transport in a quantum wire. Even if these interactions have no significant effect on charge transport, they strongly influence the transport of spin. We use the quantum Boltzmann equation in the collision approximation to derive equations of motion for spin current and magnetization. In the limit of small perturbations from equilibrium, we explain the existence of `precessional' and `diffusive' behaviors. We also discuss the low-temperature non-linear decay of an uniform spin current outside the hydrodynamic regime. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0106/0106456v1.pdf"}
{"id": "cond-mat0107370", "abstract": "  A new DC-SQUID is proposed that exploits the properties of the grain boundary junctions in high T_c superconductors. The orientations of the grain boundaries are chosen in such a way to establish a pi/2 (rather than 0 or pi) phase difference between the equilibrium phases of the two Josephson junctions in the SQUID loop. This property is exploited to increase the sensitivity and direction dependence of the SQUID for measuring magnetic flux without additional flux generating coils. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0107/0107370v1.pdf"}
{"id": "cond-mat0108098", "abstract": "  We consider a non-interacting system of electrons on a clean one-channel Aharonov-Bohm ring which is threaded by a fluctuating magnetic flux. The flux derives from a Caldeira-Leggett bath of harmonic oscillators. We address the influence of the bath on the following properties: one- and two-particle Green's functions, dephasing, persistent current and visibility of the Aharonov-Bohm effect in cotunneling transport through the ring. For the bath spectra considered here (including Nyquist noise of an external coil), we find no dephasing in the linear transport regime at zero temperature.   PACS numbers: 73.23.-b, 73.23.Hk, 73.23.Ra, 03.65.Yz ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0108/0108098v2.pdf"}
{"id": "cond-mat0109377", "abstract": "  We study a toy model for electrolytic soap films, the two-dimensional two-component plasma. This model is exactly solvable for a special value of the coulombic coupling constant β q^2=2. This allows us to compute the disjoining pressure of a film and to study its stability. We found that the Coulomb interaction plays an important role in this stability. Also the adhesivity that measures the attraction of soap anions to the boundaries is very important. For large adhesivity the film is stable, whereas for small adhesivity a collapse could occur. We also study the density and correlations in the film. The charge density near the boundary shows a double layered profile. We show that the charge correlations verify a certain number of sum rules. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0109/0109377v1.pdf"}
{"id": "cond-mat0111582", "abstract": "  Interesting physical results can be obtained from sigma models by taking the number of fields N to zero. I discuss how one can make sense of this limit by using exact S matrix techniques. I review how this can be done for the case of self-avoiding polymers, and speculate on the application to the replica limit of disordered systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0111/0111582v1.pdf"}
{"id": "cond-mat0112082", "abstract": "  In recent years the modelling of traffic flow using methods from statistical physics, especially cellular automata models have allowed simulations of large traffic networks faster than real time. In this paper, we study a probabilistic cellular automaton model for microsimulations of traffic flow of automated vehicles in highways. This model describes single-lane traffic flow on a ring. We study the equilibrium properties by including a parameter of safe distance in the model and calculate the so-called fundamental diagrams (flow vs. density graph) considering parallel dynamics. This is done numerically by computer simulations of the model and by means of an analysis of speed variance. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0112/0112082v1.pdf"}
{"id": "cond-mat0201080", "abstract": "  We consider network models for localisation problems belonging to symmetry class C. This symmetry class arises in a description of the dynamics of quasiparticles for disordered spin-singlet superconductors which have a Bogoliubov - de Gennes Hamiltonian that is invariant under spin rotations but not under time-reversal. Our models include but also generalise the one studied previously in the context of the spin quantum Hall effect. For these systems we express the disorder-averaged conductance and density of states in terms of sums over certain classical random walks, which are self-avoiding and have attractive interactions. A transition between localised and extended phases of the quantum system maps in this way to a similar transition for the classical walks. In the case of the spin quantum Hall effect, the classical walks are the hulls of percolation clusters, and our approach provides an alternative derivation of a mapping first established by Gruzberg, Read and Ludwig, Phys. Rev. Lett. 82, 4254 (1999). ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0201/0201080v1.pdf"}
{"id": "cond-mat0201584", "abstract": "  A linear spin-wave approach, a variational method and exact diagonlization are used to investigate the magnetic long-range order (LRO) of the spin-1/2 Heisenberg antiferromagnet on a two-dimensional 1/7-depleted triangular (maple leaf) lattice consisting of triangles and hexagons only. This lattice has z=5 nearest neighbors and its coordination number z is therefore between those of the triangular (z=6) and the kagome (z=4) lattices. Calculating spin-spin correlations, sublattice magnetization, spin stiffness, spin-wave velocity and spin gap we find that the classical 6-sublattice LRO is strongly renormalized by quantum fluctuations, however, remains stable also in the quantum model. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0201/0201584v1.pdf"}
{"id": "cond-mat0203346", "abstract": "  A two-lane extension of a recently proposed cellular automaton model for traffic flow is discussed. The analysis focuses on the reproduction of the lane usage inversion and the density dependence of the number of lane changes. It is shown that the single-lane dynamics can be extended to the two-lane case without changing the basic properties of the model which are known to be in good agreement with empirical single-vehicle data. Therefore it is possible to reproduce various empirically observed two-lane phenomena, like the synchronization of the lanes, without fine-tuning of the model parameters. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0203/0203346v1.pdf"}
{"id": "cond-mat0203463", "abstract": "  A two-dimensional cellular automaton is introduced to model the flow and jamming of vehicular traffic in cities. Each site of the automaton represents a crossing where a finite number of cars can wait approaching the crossing from each of the four directions. The flow of cars obeys realistic traffic rules. We investigate the dependence of the average velocity of cars on the global traffic density. At a critical threshold for the density the average velocity reduces drastically caused by jamming. For the low density regime we provide analytical results which agree with the numerical results. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0203/0203463v1.pdf"}
{"id": "cond-mat0204574", "abstract": "  In this paper we compare market price fluctuations with the response to fundamental price drops within the Lux-Marchesi model which is able to reproduce the most important stylized facts of real market data. Major differences can be observed between the decay of spontaneous fluctuations and of changes due to external perturbations reflecting the absence of detailed balance, i.e., of the validity of the fluctuation-dissipation theorem. We found that fundamental price drops are followed by an overshoot with a rather robust characteristic time. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0204/0204574v1.pdf"}
{"id": "cond-mat0205494", "abstract": "  The mechanisms of stability or instability in the strained alloy film growth are of intense current interest to both theorists and experimentalists. We consider dislocation-free, coherent, growing alloy films which could exhibit a morphological instability without nucleation. We investigate such strained films by developing a nonequilibrium, continuum model and by performing a linear stability analysis. The couplings of film-substrate misfit strain, compositional stress, deposition rate, and growth temperature determine the stability of film morphology as well as the surface spinodal decomposition. We consider some realistic factors of epitaxial growth, in particular the composition dependence of elastic moduli and the coupling between top surface and underlying bulk of the film. The interplay of these factors leads to new stability results. In addition to the stability diagrams both above and below the coherent spinodal temperature, we also calculate the kinetic critical thickness for the onset of instability as well as its scaling behavior with respect to misfit strain and deposition rate. We apply our results to some real growth systems and discuss the implications related to some recent experimental observations. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0205/0205494v1.pdf"}
{"id": "cond-mat0206465", "abstract": "  We analyze the effective electron-electron interaction in a two dimensional polarized paramagnetic system. The spin degree of freedom, s, is manifestly present in the expressions of spin dependent local field factors that describe the short range exchange (x) and correlation (c) effects. Starting from the exact asymptotic values of the local field correction functions for large and small momentum at zero frequency we obtain self-consistent expressions across the whole spectrum of momenta. Then, the effective interaction between two electrons with spins s and s' is calculated. We find that the four effective interactions, up-up, up-down, down-up and down-down, are different. We also obtain their qualitative dependence on the electronic density and polarization and note that these results are independent of the approximation used for the local field correction functions at intermediate momenta. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0206/0206465v1.pdf"}
{"id": "cond-mat0207698", "abstract": "  We investigate the constitutive response of two-dimensional packed samples of polygons using molecular dynamics simulation. The incremental elasto-plastic response is examined in the pre-failure regime. Besides the Young modulus and the Poisson ratio, an additional parameter must be included, which takes into account the anisotropy of the elastic response. The plastic deformations are described by the introduction of the yield and the flow directions. These directions do not agree, which reproduces the non-associated feature of realistic soils. In order to detect the yield surface, different loading-unloading-reloading tests were performed. During the reload path, it is found that the yielding develops continuously with the amplitude of loading, which does not allow to identify a purely elastic regime. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0207/0207698v1.pdf"}
{"id": "cond-mat0208241", "abstract": "  We review the basic ideas of the dynamical mean field theory (DMFT) and some of the insights into the electronic structure of strongly correlated electrons obtained by this method in the context of model Hamiltonians. We then discuss the perspectives for carrying out more realistic DMFT studies of strongly correlated electron systems and we compare it with existent methods, LDA and LDA+U. We stress the existence of new functionals for electronic structure calculations which allow us to treat situations where the single–particle description breaks down such as the vicinity of the Mott transition. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0208/0208241v1.pdf"}
{"id": "cond-mat0208310", "abstract": "  The Interactive Minority Game (IMG) is an online version of the traditional Minority Game in which human players can enter into competition with the traditional computer-controlled agents. Through the rich (and, importantly, analytically understood) behaviour of the MG, we can explore humans' behaviour in different kinds of market–crowded, efficient, critical–with a high degree of control. To make the game easily understandable even to those who are encountering it for the first time, we have presented the game with a rather simplified interface; in this working paper we explain the underlying technical aspects for those who have experience with the traditional MG. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0208/0208310v1.pdf"}
{"id": "cond-mat0210033", "abstract": "  We investigate the crossover from the semiclassical to the quantum description of electron energy states in a chaotic metal grain connected to a superconductor. We consider the influence of scattering off point impurities (quantum disorder) and of quantum diffraction (quantum chaos) on the electron density of states. We show that both the quantum disorder and the quantum chaos open a gap near the Fermi energy. The size of the gap is determined by the mean free time in disordered systems and by the Ehrenfest time in clean chaotic systems. Particularly, if both times become infinitely large, the density of states is gapless, and if either of these times becomes shorter than the electron escape time, the density of states is described by random matrix theory. Using the Usadel equation, we also study the density of states in a grain connected to a superconductor by a diffusive contact. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0210/0210033v1.pdf"}
{"id": "cond-mat0211519", "abstract": "  We derive an order-parameter field theory for a quantum phase transition between a disordered metal and an exotic (non-s-wave) superconductor. Mode coupling effects between the order parameter and other fermionic soft modes lead to an effective long-range interaction between the anomalous density fluctuations which is reflected in singularities in the free energy functional. However, this long-range interaction is not strong enough to suppress disorder fluctuations. The asymptotic critical region is characterized by run-away flow to large disorder. For weak coupling, this asymptotic region is very narrow. It is preempted by a wide crossover regime with mean-field critical behavior and, in the p-wave case, logarithmic corrections to scaling in all dimensions. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0211/0211519v3.pdf"}
{"id": "cond-mat0301125", "abstract": "  A method-of-moments scheme is invoked to compute the asymptotic, long-time mean (or composite) velocity and dispersivity (effective diffusivity) of a two-state particle undergoing one-dimensional convective-diffusive motion accompanied by a reversible linear transition (“chemical reaction” or “change in phase”) between these states. The instantaneous state-specific particle velocity is assumed to depend only upon the instantaneous state of the particle, and the transition between states is assumed to be governed by spatially-independent, first-order kinetics. Remarkably, even in the absence of molecular diffusion, the average transport of the “composite” particle exhibits gaussian diffusive behavior in the long-time limit, owing to the effectively stochastic nature of the overall transport phenomena induced by the interstate transition. The asymptotic results obtained are compared with numerical computations. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0301/0301125v1.pdf"}
{"id": "cond-mat0302357", "abstract": "  We discuss the dynamics of a spin coupled to a damped harmonic oscillator. This system can be mapped to a spin-boson model with a structured bath, i.e. the spectral function of the bath has a resonance peak. We diagonalize the model by means of infinitesimal unitary transformations (flow equations), thereby decoupling the small quantum system from its environment, and calculate spin-spin correlation functions. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0302/0302357v1.pdf"}
{"id": "cond-mat0303417", "abstract": "  We investigate the resonance type behaviour of an overdamped Brownian particle in a bistable potential driven by external periodic signal. It has been shown previously that the input energy pumped into the system by the external drive shows resonance type behaviour as function of noise strength. We further extend this idea to study the behaviour as function of frequency of the external driving force and show the occurrence of similar nonmonotonic behaviour, which can be ascribed as a signature of bona fide stochastic resonance. Both weak and strong driving limit has been explored indicating the occurrence of marginal supra-threshold stochastic resonance in a bistable potential system. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0303/0303417v1.pdf"}
{"id": "cond-mat0304207", "abstract": "  The budding yeast Saccharomyces cerevisiae is the first eukaryote whose genome has been completely sequenced. It is also the first eukaryotic cell whose proteome (the set of all proteins) and interactome (the network of all mutual interactions between proteins) has been analyzed. In this paper we study the structure of the yeast protein complex network in which weighted edges between complexes represent the number of shared proteins. It is found that the network of protein complexes is a small world network with scale free behavior for many of its distributions. However we find that there are no strong correlations between the weights and degrees of neighboring complexes. To reveal non-random features of the network we also compare it with a null model in which the complexes randomly select their proteins. Finally we propose a simple evolutionary model based on duplication and divergence of proteins. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0304/0304207v3.pdf"}
{"id": "cond-mat0304429", "abstract": "  For many years it had been believed that steric compatibility of helix interfaces could be the source of the observed preference for particular angles between neighbouring helices as emerging from statistical analysis of protein databanks. Several elegant models describing how side chains on helices can interdigitate without steric clashes were able to account quite reasonably for the observed distributions. However, it was later recognized (Bowie, 1997 and Walther, 1998) that the “bare” measured angle distribution should be corrected to avoid statistical bias. Disappointingly, the rescaled distributions dramatically lost their similarity with theoretical predictions casting many doubts on the validity of the geometrical assumptions and models. In this report we elucidate a few points concerning the proper choice of the random reference distribution. In particular we show the existence of crucial corrections due to the correct implementation of the approach used to discriminate whether two helices are in contact or not and to measure their relative orientations. By using this new rescaling, the “true” packing angle preferences are well described, even more than with the original “bare” distribution, by regular packing models. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0304/0304429v1.pdf"}
{"id": "cond-mat0304504", "abstract": "  It has been recently shown theoretically that a topological defect in a 1D periodic potential may give rise to two localized states within the energy gaps. In this work we present an experimental realization of this effect for the case of torsional waves in elastic rods. We also show numerically that three, or even more, localized states can be present if the parameters characterizing the topological defect are suitably varied. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0304/0304504v1.pdf"}
{"id": "cond-mat0304650", "abstract": "  We propose two loading mechanisms of a degenerate Bose gas into a surface trap. This trap relies on the dipole potential produced by two evanescent optical waves far detuned from the atomic resonance, yielding a strongly anisotropic trap with typical frequencies 40 Hz x 65 Hz x 30 kHz. We present numerical simulations based on the time-dependent Gross-Pitaevskii equation of the transfer process from a conventional magnetic trap into the surface trap. We show that, despite a large discrepancy between the oscillation frequencies along one direction in the initial and final traps, a loading time of a few tens of milliseconds would lead to an adiabatic transfer. Preliminary experimental results are presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0304/0304650v1.pdf"}
{"id": "cond-mat0309412", "abstract": "  EuB_6 is a magnetic semiconductor in which defects introduce charge carriers into the conduction band with the Fermi energy varying with temperature and magnetic field. We present experimental and theoretical work on the electronic magnetotransport in single-crystalline EuB_6. Magnetization, magnetoresistance and Hall effect data were recorded at temperatures between 2 and 300 K and in magnetic fields up to 5.5 T. The negative magnetoresistance is well reproduced by a model in which the spin disorder scattering is reduced by the applied magnetic field. The Hall effect can be separated into an ordinary and an anomalous part. At 20 K the latter accounts for half of the observed Hall voltage, and its importance decreases rapidly with increasing temperature. As for Gd and its compounds, where the rare-earth ion adopts the same Hund's rule ground state as Eu^2+ in EuB_6, the standard antisymmetric scattering mechanisms underestimate the size of this contribution by several orders of magnitude, while reproducing its shape almost perfectly. Well below the bulk ferromagnetic ordering at T_C = 12.5 K, a two-band model successfully describes the magnetotransport. Our description is consistent with published de Haas van Alphen, optical reflectivity, angular-resolved photoemission, and soft X-ray emission as well as absorption data, but requires a new interpretation for the gap feature deduced from the latter two experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0309/0309412v2.pdf"}
{"id": "cond-mat0309544", "abstract": "  We characterize the different morphological phases that occur in a simple one-dimensional model of propagation of innovations among economic agents [X. Guardiola, et. al., Phys. Rev E 66, 026121 (2002)]. We show that the model can be regarded as a nonequilibrium surface growth model. This allows us to demonstrate the presence of a continuous roughening transition between a flat (system size independent fluctuations) and a rough phase (system size dependent fluctuations). Finite-size scaling studies at the transition strongly suggest that the dynamic critical transition does not belong to directed percolation and, in fact, critical exponents do not seem to fit in any of the known universality classes of nonequilibrium phase transitions. Finally, we present an explanation for the occurrence of the roughening transition and argue that avalanche driven dynamics is responsible for the novel critical behavior. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0309/0309544v1.pdf"}
{"id": "cond-mat0310172", "abstract": "  Few-electron systems confined in two-dimensional parabolic quantum dots at high magnetic fields are studied by the Hartree-Fock (HF) and exact diagonalization methods. A generalized multicenter Gaussian basis is proposed in the HF method. A comparison of the HF and exact results allows us to discuss the relevance of the symmetry of the charge density distribution for the accuracy of the HF method. It is shown that the energy estimates obtained with the broken-symmetry HF wave functions become exact in the infinite magnetic-field limit. In this limit the charge density of the broken-symmetry solution can be identified with the classical charge distribution. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0310/0310172v2.pdf"}
{"id": "cond-mat0311503", "abstract": "  We present a comprehensive theoretical treatment of the effect of electron-phonon interactions in molecular transistors, including both quantal and classical limits and we study both equilibrated and out of equilibrium phonons. We present detailed results for conductance, noise and phonon distribution in two regimes. One involves temperatures large as compared to the rate of electronic transitions on and off the dot; in this limit our approach yields classical rate equations, which are solved numerically for a wide range of parameters. The other regime is that of low temperatures and weak electron-phonon coupling where a perturbative approximation in the Keldysh formulation can be applied. The interplay between the phonon-induced renormalization of the density of states on the quantum dot and the phonon-induced renormalization of the dot-lead coupling is found to be important. Whether or not the phonons are able to equilibrate in a time rapid compared to the transit time of an electron through the dot is found to affect the conductance. Observable signatures of phonon equilibration are presented. We also discuss the nature of the low-T to high-T crossover. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0311/0311503v2.pdf"}
{"id": "cond-mat0311608", "abstract": "  Electron interference in mesoscopic devices irradiated by external non-classical microwaves, is considered. In the case of one-mode microwaves, it is shown that both the average intensity and the spectral density of the interfering electrons are sensitive to the quantum noise of the microwaves. The results for various quantum states of the microwaves are compared and contrasted with the classical case. Separable and entangled two-mode microwaves are also considered and their effect on electron average intensity and autocorrelation, is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0311/0311608v1.pdf"}
{"id": "cond-mat0312113", "abstract": "  A kinetic model for the Boltzmann equation is proposed and explored as a practical means to investigate the properties of a dilute granular gas. It is shown that all spatially homogeneous initial distributions approach a universal \"homogeneous cooling solution\" after a few collisions. The homogeneous cooling solution (HCS) is studied in some detail and the exact solution is compared with known results for the hard sphere Boltzmann equation. It is shown that all qualitative features of the HCS, including the nature of over population at large velocities, are reproduced semi-quantitatively by the kinetic model. It is also shown that all the transport coefficients are in excellent agreement with those from the Boltzmann equation. Also, the model is specialized to one having a velocity independent collision frequency and the resulting HCS and transport coefficients are compared to known results for the Maxwell Model. The potential of the model for the study of more complex spatially inhomogeneous states is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0312/0312113v2.pdf"}
{"id": "cond-mat0312458", "abstract": "  The electronic properties of the carbon substituted MgB_2 single crystals are reported. The carbon substitution drops T_c below 2 K. In-plane resistivity shows a remarkable increase in residual resistivity by C-substitution, while the change of in-plane/out-of-plane Hall coefficients is rather small. Raman scattering spectra indicate that the E_2g-phonon frequency radically hardens with increasing the carbon-content, suggesting the weakening of electron-phonon coupling. Another striking C-effect is the increases of the second critical fields in both in-plane and out-of-plane directions, accompanied by a reduction in the anisotropy ratio. The possible changes in the electronic state and the origin of T_c-suppression by C-substitution are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0312/0312458v1.pdf"}
{"id": "cond-mat0401003", "abstract": "  We investigate the phase behavior of tetrapods, hard non-convex bodies formed by 4 rods connected under tetrahedral angles. We predict that, depending on the relative lengths of the rods these particles can form a uniaxial nematic phase, and more surprisingly they can exhibit a cubatic phase, a special case of the biaxial nematic phase. These predictions may be experimentally testable, as experimental realizations of tetrapods have recently become available. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0401/0401003v1.pdf"}
{"id": "cond-mat0401077", "abstract": "  We present a simple calculational scheme for superconducting properties under magnetic fields. A combination of an approximate analytic solution with a free energy functional in the quasiclassical theory provides a wide use formalism for spatial-averaged thermodynamic properties, and requires a little numerical computation. The theory covers multiband superconductors with various set of singlet and unitary triplet pairings in the presence of an impurity scattering. It is also applicable to analyze experimental results in a rotating magnetic field with help of band structure calculations. We demonstrate the application to s-wave, d_x^2-y^2-wave and two-band s-wave pairings, and discuss the validity of the theory comparing with previous numerical studies. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0401/0401077v3.pdf"}
{"id": "cond-mat0402424", "abstract": "  We report molecular-dynamics simulation results performed for a model of molecular liquid orthoterphenyl in supercooled states, which we then compare with both experimental data and mode-coupling-theory (MCT) predictions, aiming at a better understanding of structural relaxation in orthoterphenyl. We pay special attention to the wavenumber dependence of the collective dynamics. It is shown that the simulation results for the model share many features with experimental data for real system, and that MCT captures the simulation results at the semiquantitative level except for intermediate wavenumbers connected to the overall size of the molecule. Theoretical results at the intermediate wavenumber region are found to be improved by taking into account the spatial correlation of the molecule's geometrical center. This supports the idea that unusual dynamical properties at the intermediate wavenumbers, reported previously in simulation studies for the model and discernible in coherent neutron-scattering experimental data, are basically due to the coupling of the rotational motion to the geometrical-center dynamics. However, there still remain qualitative as well as quantitative discrepancies between theoretical prediction and corresponding simulation results at the intermediate wavenumbers, which call for further theoretical investigation. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0402/0402424v1.pdf"}
{"id": "cond-mat0403694", "abstract": "  We present a comprehensive study of the properties of the off-resonant conductance spectrum in oligomer nanojunctions between graphitic electrodes. By employing first-principle-based methods and the Landauer approach of quantum transport, we identify how the electronic structure of the molecular junction components is reflected in electron transport across such systems. For virtually all energies within the conduction gap of the corresponding idealised polymer chain, we show that: a) the inverse decay length of the tunnelling conductance is intrinsically defined by the complex-band structure of the molecular wire despite ultrashort oligomer lengths of few monomer units, and b) the contact conductance crucially depends on both the local density of states on the metal side and the realised interfacial contact. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0403/0403694v1.pdf"}
{"id": "cond-mat0406723", "abstract": "  We study the collective behaviour of a close packed monolayer of non-Brownian particles at a fluid-liquid interface. Such a particle raft forms a two-dimensional elastic solid and can support anisotropic stresses and strains, e.g. it buckles in uniaxial compression and cracks in tension. We characterise this solid in terms of a Young's modulus and Poisson ratio derived from simple theoretical considerations and show the validity of these estimates by using an experimental buckling assay to deduce the Young's modulus. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0406/0406723v2.pdf"}
{"id": "cond-mat0407194", "abstract": "  We develop a theory which describes hybrid structures consisting out of superconducting and ferromagnetic parts. We give two examples for applications. First, we consider a hybrid structure containing a strong ferromagnet in the ballistic limit. Second, we study for a weak ferromagnet the influence of a domain wall on the superconducting proximity effect. In both cases we account quantitatively for the mixing between singlet and triplet correlations. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0407/0407194v1.pdf"}
{"id": "cond-mat0408187", "abstract": "  The discovery and analysis of community structure in networks is a topic of considerable recent interest within the physics community, but most methods proposed so far are unsuitable for very large networks because of their computational cost. Here we present a hierarchical agglomeration algorithm for detecting community structure which is faster than many competing algorithms: its running time on a network with n vertices and m edges is O(m d log n) where d is the depth of the dendrogram describing the community structure. Many real-world networks are sparse and hierarchical, with m   n and d   log n, in which case our algorithm runs in essentially linear time, O(n log^2 n). As an example of the application of this algorithm we use it to analyze a network of items for sale on the web-site of a large online retailer, items in the network being linked if they are frequently purchased by the same buyer. The network has more than 400,000 vertices and 2 million edges. We show that our algorithm can extract meaningful communities from this network, revealing large-scale patterns present in the purchasing habits of customers. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0408/0408187v2.pdf"}
{"id": "cond-mat0408531", "abstract": "  We study an economic model where agents trade a variety of products by using one of three competing rules: \"need\", \"greed\" and \"noise\". We find that the optimal strategy for any agent depends on both product composition in the overall market and composition of strategies in the market. In particular, a strategy that does best on pairwise competition may easily do much worse when all are present, leading, in some cases, to a \"paper, stone, scissors\" circular hierarchy. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0408/0408531v1.pdf"}
{"id": "cond-mat0409303", "abstract": "  Vibration properties of Zn(1-x)Be(x)Se, a mixed II-VI semiconductor haracterized by a high contrast in elastic properties of its pure constituents, ZnSe and BeSe, are simulated by first-principles calculations of electronic structure, lattice relaxation and frozen phonons. The calculations within the local density approximation has been done with the Siesta method, using norm-conserving pseudopotentials and localized basis functions; the benchmark calculations for pure endsystems were moreover done also by all-electron WIEN2k code. An immediate motivation for the study was to analyze, at the microscopic level, the appearance of anomalous phonon modes early detected in Raman spectra in the intermediate region (20 to 80", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0409/0409303v2.pdf"}
{"id": "cond-mat0409525", "abstract": "  Mean-field evolution equations for the exciton and photon populations and polarizations (Bloch-Lamb equations) are written and numerically solved in order to describe the dynamics of electronic states in a quantum dot coupled to the photon field of a microcavity. The equations account for phase space filling effects and Coulomb interactions among carriers, and include also (in a phenomenological way) incoherent pumping of the quantum dot, photon losses through the microcavity mirrors, and electron-hole population decay due to spontaneous emission of the dot. When the dot may support more than one electron-hole pair, asymptotic oscillatory states, with periods between 0.5 and 1.5 ps, are found almost for any values of the system parameters. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0409/0409525v1.pdf"}
{"id": "cond-mat0409763", "abstract": "  The fractal structure of a white cauliflower is investigated by box-counting method of its cross-section. The capacity dimension of the cross-section is 1.88 ± 0.02 independent of directions. From the result, we predict that the capacity dimension of the cauliflower is about 2.8. The vertical cross-section of the cauliflower is modeled into a self-similar set of a rectangular tree. We discuss the condition of the fractal object in the tree, and show that the vertical cross-section has an angle of 67 degrees in our model. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0409/0409763v1.pdf"}
{"id": "cond-mat0410166", "abstract": "  The thermal properties of graphitic ribbon are investigated based on Brenner's empirical potential. The reliability and usefulness of the empirical potential to address the thermal properties of covalent-bonded carbon nanostructures are verified through a comparison of phonon dispersion relations and the density of states of carbon nanotubes with first-principles calculations. The analysis reveals unique edge-phonon states that are highly localized at edge carbon atoms of both armchair and zigzag ribbons. Applying the phonon dispersion relations to the Landauer formula of phonon transport, the quantization and universal features of the low-temperature thermal conductance of graphitic ribbon are elucidated, and it is found that the width of the quantization plateau in the low-temperature region is inversely proportional to the ribbon width. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0410/0410166v1.pdf"}
{"id": "cond-mat0410234", "abstract": "  We present a theoretical analysis of three-dimensional (3D) matter-wave solitons and their stability properties in coupled atomic and molecular Bose-Einstein condensates (BEC). The soliton solutions to the mean-field equations are obtained in an approximate analytical form by means of a variational approach. We investigate soliton stability within the parameter space described by the atom-molecule conversion coupling, atom-atom s-wave scattering, and the bare formation energy of the molecular species. In terms of ordinary optics, this is analogous to the process of sub/second-harmonic generation in a quadratic non-linear medium modified by a cubic nonlinearity, together with a phase mismatch term between the fields. While the possibility of formation of multidimensional spatio-temporal solitons in pure quadratic media has been theoretically demonstrated previously, here we extend this prediction to matter-wave interactions in BEC systems where higher-order non-linear processes due to interparticle collisions are unavoidable and may not be neglected. The stability of the solitons predicted for repulsive atom-atom interactions is investigated by direct numerical simulations of the equations of motion in a full 3D lattice. Our analysis also leads to a possible technique for demonstrating the ground state of the Schroedinger-Newton and related equations that describe Bose-Einstein condensates with non-local inter-particle forces. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0410/0410234v2.pdf"}
{"id": "cond-mat0411630", "abstract": "  We analyze the existence and the size of the giant component in the stationary state of a Markovian model for bipartite multigraphs, in which the movement of the edge ends on one set of vertices of the bipartite graph is a zero-range process, the degrees being static on the other set. The analysis is based on approximations by independent variables and on the results of Molloy and Reed for graphs with prescribed degree sequences. The possible types of phase diagrams are identified by studying the behavior below the zero-range condensation point. As a specific example, we consider the so-called Evans interaction. In particular, we examine the values of a critical exponent, describing the growth of the giant component as the value of the dilution parameter controlling the connectivity is increased above the critical threshold. Rigorous analysis spans a large portion of the parameter space of the model exactly at the point of zero-range condensation. These results, supplemented with conjectures supported by Monte Carlo simulations, suggest that the phenomenological Landau theory for percolation on graphs is not broken by the fluctuations. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0411/0411630v1.pdf"}
{"id": "cond-mat0503468", "abstract": "  A nematic liquid crystal in contact with a grating surface possessing an alternating stripe pattern of locally homeotropic and planar anchoring is studied within the Frank–Oseen model. The combination of both chemical and geometrical surface pattern leads to rich phase diagrams, involving a homeotropic, a planar, and a tilted nematic texture. The effect of the groove depth and the anchoring strengths on the location and the order of phase transitions between different nematic textures is studied. A zenithally bistable nematic device is investigated by confining a nematic liquid crystal between the patterned grating surface and a flat substrate with strong homeotropic anchoring. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0503/0503468v1.pdf"}
{"id": "cond-mat0504279", "abstract": "  Coherent bremsstrahlung of high energy electrons moving in a three-dimensional imperfect periodic lattice consisting of a complicated system of atoms is considered. On the basis of the normalized probability density function of the distribution of atomic centers in the fundamental cell the relations describing coherent and incoherent contributions into cross sections are obtained. In particular, the cross section of coherent bremsstrahlung in complex polyatomic single crystals is found.   The peculiarities of formation and possibilities of utilization of coherent processes are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0504/0504279v1.pdf"}
{"id": "cond-mat0505658", "abstract": "  We present theoretical results concerning inelastic light (Raman) scattering from semiconductor quantum dots. The characteristics of each dot state (whether it is a collective or single-particle excitation, its multipolarity, and its spin) are determined independently of the Raman spectrum, in such a way that common beliefs used for level assignments in experimental spectra can be tested. We explore the usefulness of below band gap excitation and an external magnetic field to identify charge and spin excited states of a collective or single-particle nature. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0505/0505658v1.pdf"}
{"id": "cond-mat0506284", "abstract": "  Holographic optical tweezers use computer-generated holograms to create arbitrary three-dimensional configurations of single-beam optical traps useful for capturing, moving and transforming mesoscopic objects. Through a combination of beam-splitting, mode forming, and adaptive wavefront correction, holographic traps can exert precisely specified and characterized forces and torques on objects ranging in size from a few nanometers to hundreds of micrometers. With nanometer-scale spatial resolution and real-time reconfigurability, holographic optical traps offer extraordinary access to the microscopic world and already have found applications in fundamental research and industrial applications. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0506/0506284v1.pdf"}
{"id": "cond-mat0506496", "abstract": "  We evaluate the low-lying oscillation modes and the ballistic expansion properties of a harmonically trapped gas of fermionic K40 atoms containing thermal Rb87 impurities as functions of the anisotropy of the trap. Numerical results are obtained by solving the Vlasov-Landau equations for the one-body phase-space distribution functions and are used to test simple scaling Ansatzes. Starting from the gas in a weak impurity-scattering regime inside a spherical trap, the time scales associated to motions in the axial and azimuthal directions enter into competition as the trap is deformed to an elongated cigar-like shape. This competition gives rise to coexistence of collisionless and hydrodynamic behaviors in the low-lying surface modes of the gas as well as to a dependence of the aspect ratio of the expanding cloud on the collision time. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0506/0506496v1.pdf"}
{"id": "cond-mat0506667", "abstract": "  We study dynamical properties of the anisotropic triangular quantum antiferromagnet Cs_2CuCl_4. Inelastic neutron scattering measurements have established that the dynamical spin correlations cannot be understood within a linear spin wave analysis. We go beyond linear spin wave theory by taking interactions between magnons into account in a 1/S expansion. We determine the dynamical structure factor and carry out extensive comparisons with experimental data. We find that compared to linear spin wave theory a significant fraction of the scattering intensity is shifted to higher energies and strong scattering continua are present. However, the 1/S expansion fails to account for the experimentally observed large quantum renormalization of the exchange energies. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0506/0506667v1.pdf"}
{"id": "cond-mat0507088", "abstract": "  We perform molecular dynamics simulations of 512 water-like molecules that interact via the TIP5P potential and are confined between two smooth hydrophobic plates that are separated by 1.10 nm. We find that the anomalous thermodynamic properties of water are shifted to lower temperatures relative to the bulk by ≈ 40 K. The dynamics and structure of the confined water resemble bulk water at higher temperatures, consistent with the shift of thermodynamic anomalies to lower temperature. Due to this T shift, our confined water simulations (down to T = 220 K) do not reach sufficiently low temperature to observe a liquid-liquid phase transition found for bulk water at T≈ 215 K using the TIP5P potential. We find that the different crystalline structures that can form for two different separations of the plates, 0.7 nm and 1.10 nm, have no counterparts in the bulk system, and discuss the relevance to experiments on confined water. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0507/0507088v1.pdf"}
{"id": "cond-mat0507292", "abstract": "  We demonstrate that the nonlinear I-V characteristics of a two probe conductor is not an even function of magnetic field. While the conductance of a two-probe conductor is even in magnetic field, we find that already the contributions to the current which are second order in voltage, are in general not even. This implies a departure from the Onsager microreversibility principle already in the weakly nonlinear regime. Interestingly, the effect that we find is due to the Coulomb interaction. A measurement of the magnetic field asymmetry can be used to determine the effective interaction strength. As a generic example, we discuss the I-V characteristics of a chaotic quantum dot. The ensemble averaged I-V of such a cavity is linear: nonlinearities are due to quantum interference. Consequently, phase-breaking reduces the asymmetry. We support this statement with a calculation which treats inelastic scattering with the help of a voltage probe. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0507/0507292v1.pdf"}
{"id": "cond-mat0508283", "abstract": "  Subsequent to the ideas presented in our previous papers [J.Phys.: Condens. Matter 14 (2002) 13777 and Eur. Phys. J. B 42 (2004) 529], we discuss here in detail a new analytical approach to calculating the phase-diagram for the Anderson localization in arbitrary spatial dimensions. The transition from delocalized to localized states is treated as a generalized diffusion which manifests itself in the divergence of averages of wavefunctions (correlators). This divergence is controlled by the Lyapunov exponent γ, which is the inverse of the localization length, ξ=1/γ. The appearance of the generalized diffusion arises due to the instability of a fundamental mode corresponding to correlators. The generalized diffusion can be described in terms of signal theory, which operates with the concepts of input and output signals and the filter function. Delocalized states correspond to bounded output signals, and localized states to unbounded output signals, respectively. Transition from bounded to unbounded signals is defined uniquely be the filter function H(z). Simplifications in the mathematical derivations of the previous papers (averaging over initial conditions) are shown to be mathematically rigorous shortcuts. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0508/0508283v1.pdf"}
{"id": "cond-mat0509187", "abstract": "  Standard stochastic Loewner evolution (SLE) is driven by a continuous Brownian motion, which then produces a continuous fractal trace. If jumps are added to the driving function, the trace branches. We consider a generalized SLE driven by a superposition of a Brownian motion and a stable Levy process. The situation is defined by the usual SLE parameter, κ, as well as α which defines the shape of the stable Levy distribution. The resulting behavior is characterized by two descriptors: p, the probability that the trace self-intersects, and p̃, the probability that it will approach arbitrarily close to doing so. Using Dynkin's formula, these descriptors are shown to change qualitatively and singularly at critical values of κ and α. It is reasonable to call such changes “phase transitions”. These transitions occur as κ passes through four (a well-known result) and as α passes through one (a new result). Numerical simulations are then used to explore the associated touching and near-touching events. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0509/0509187v2.pdf"}
{"id": "cond-mat0509611", "abstract": "  We investigate the spin dynamics and relaxation in remotely-doped two dimensional electron systems where the dopants lead to random fluctuations of the Rashba spin-orbit coupling. Due to the resulting random spin precession, the spin relaxation time is limited by the strength and spatial scale of the random contribution to the spin-orbit coupling. We concentrate on the role of the randomness for two systems where the direction of the spin-orbit field does not depend on the electron momentum: the spin field-effect transistor with balanced Rashba and Dresselhaus couplings and the (011) quantum well. Both of these systems are considered as promising for the spintronics applications because of the suppression of the Dyakonov-Perel' mechanism there makes the realization of a spin field effect transistor in the diffusive regime possible. We demonstrate that the spin relaxation through the randomness of spin-orbit coupling imposes important physical limitations on the operational properties of these devices. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0509/0509611v1.pdf"}
{"id": "cond-mat0509760", "abstract": "  Magnetic nanostructures on non-magnetic or magnetic substrates have attracted strong attention due to the development of new experimental methods with atomic resolution. Motivated by this progress we have extended the full-potential Korringa-Kohn-Rostoker (KKR) Green function method to treat non-collinear magnetic nanostructures on surfaces. We focus on magnetic 3d impurity nanoclusters, sitting as adatoms on or in the first surface layer on Ni(001), and investigate the size and orientation of the local moments and moreover the stabilization of non-collinear magnetic solutions. While clusters of Fe, Co, Ni atoms are magnetically collinear, non-collinear magnetic coupling is expected for Cr and Mn clusters on surfaces of elemental ferromagnets. The origin of frustration is the competition of the antiferromagnetic exchange coupling among the Cr or Mn atoms with the antiferromagnetic (for Cr) or ferromagnetic (for Mn) exchange coupling between the impurities and the substrate. We find that Cr and Mn first-neighbouring dimers and a Mn trimer on Ni(001) show non-collinear behavior nearly degenerate with the most stable collinear configuration. Increasing the distance between the dimer atoms leads to a collinear behavior, similar to the one of the single impurities. Finally, we compare some of the non-collinear ab-initio results to those obtained within a classical Heisenberg model, where the exchange constants are fitted to total energies of the collinear states; the agreement is surprisingly good. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0509/0509760v1.pdf"}
{"id": "cond-mat0510455", "abstract": "  We calculate the number of metastable configurations of Ising small-world networks which are constructed upon superimposing sparse Poisson random graphs onto a one-dimensional chain. Our solution is based on replicated transfer-matrix techniques. We examine the denegeracy of the ground state and we find a jump in the entropy of metastable configurations exactly at the crossover between the small-world and the Poisson random graph structures. We also examine the difference in entropy between metastable and all possible configurations, for both ferromagnetic and bond-disordered long-range couplings. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0510/0510455v1.pdf"}
{"id": "cond-mat0601550", "abstract": "  We investigate possible parafermionic states in rapidly rotating ultracold bosonic atomic gases at lowest Landau level filling factor nu=k/2. We study how the system size and interactions act upon the overlap between the true ground state and a candidate Read-Rezayi state. We also consider the quasihole states which are expected to display non-Abelian statistics. We numerically evaluate the degeneracy of these states and show agreement with a formula given by E. Ardonne. We compute the overlaps between low-lying exact eigenstates and quasihole candidate wavefunctions. We discuss the validity of the parafermion description as a function of the filling factor. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0601/0601550v1.pdf"}
{"id": "cond-mat0603591", "abstract": "  The confinement mechanism of electrons in gated circular quantum dots is studied in a sequence of models, from self-consistent 3D Hartree calculations to the semiclassical model of Shikin et al. Separation of the vertical from transverse confinement allows accurate 2D Hartree calculations. For moderate size dots containing ∼ 50 electrons, 2D Thomas-Fermi can also be accurate. Finally, a Shikin type parameterization of the electron density allows quantitative study of the importance of the many contributions to the confinement potential. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0603/0603591v2.pdf"}
{"id": "cond-mat0604178", "abstract": "  We study the effect of the interfacial transparency on the Josephson current in a diffusive ferromagnetic contact between two superconductors. In contrast to the cases of the fully transparent and the low-transparency interfaces, the current-phase relation is shown to be nonsinusoidal for a finite transparency. It is demonstrated that even for the nearly fully transparent interfaces the small corrections due to weak interfacial disorders contribute a small second-harmonic component in the current-phase relation. For a certain thicknesses of the ferromagnetic contact and the exchange field this can lead to a tiny minimum supercurrent at the crossover between 0 and π states of the junction. Our theory has a satisfactory agreement with the recent experiments in which a finite supercurrent was observed at the transition temperature. We further explain the possibility for observation of a large residual supercurrent if the interfaces have an intermediate transparency. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0604/0604178v1.pdf"}
{"id": "cond-mat0604372", "abstract": "  We investigate the ground state of a system of interacting particles in small nonlinear lattices with M > 2 sites, using as a prototypical example the discrete nonlinear Schroedinger equation that has been recently used extensively in the contexts of nonlinear optics of waveguide arrays, and Bose-Einstein condensates in optical lattices. We find that, in the presence of attractive interactions, the dynamical scenario relevant to the ground state and the lowest-energy modes of such few-site nonlinear lattices reveals a variety of nontrivial features that are absent in the large/infinite lattice limits: the single-pulse solution and the uniform solution are found to coexist in a finite range of the lattice intersite coupling where, depending on the latter, one of them represents the ground state; in addition, the single-pulse mode does not even exist beyond a critical parametric threshold. Finally, the onset of the ground state (modulational) instability appears to be intimately connected with a non-standard (“double transcritical”) type of bifurcation that, to the best of our knowledge, has not been reported previously in other physical systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0604/0604372v1.pdf"}
{"id": "cond-mat0604431", "abstract": "  We investigated decoherence of a Josephson vortex quantum bit (qubit) in dissipative and noisy environment. As the Josephson vortex qubit (JVQ) is fabricated by using a long Josephson junction (LJJ), we use the perturbed sine-Gordon equation to describe the phase dynamics representing a two-state system and estimate the effects of quasiparticle dissipation and weakly fluctuating critical and bias currents on the relaxation time T_1 and on the dephasing time T_ϕ. We show that the critical current fluctuation does not contribute to dephasing of the qubit in the lowest order approximation. Modeling the weak current variation from magnetic field fluctuations in the LJJ by using the Gaussian colored noise with long correlation time, we show that the coherence time T_2 is limited by the low frequency current noise at very low temperatures. Also, we show that an ultra-long coherence time may be obtained from the JVQ by using experimentally accessible value of physical parameters. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0604/0604431v1.pdf"}
{"id": "cond-mat0606186", "abstract": "  It is established that liquid metals exhibit surface layering at the liquid-vapor interface, while dielectric simple systems, like those interacting through Lennard-Jones potentials, show a monotonic decay from the liquid density to that of the vapor. First principles molecular dynamics simulations of the liquid-vapor interface of several liquid metals (Li, Na, K, Rb, Cs, Mg, Ba, Al, Tl and Si), and the Na_3K_7 alloy near their triple points have been performed in order to study the atomic motion at the interface, mainly at the outer layer. Comparison with results of classical molecular dynamics simulations of a Lennard-Jones system shows interesting differences and similarities. The probability distribution function of the time of residence in a layer shows a peak at very short times and a long lasting tail. The mean residence time in a layer increases when approaching the interfacial region, slightly in the Lennard-Jones system, but strongly in the metallic systems. The motion within the layers, parallel to the interface, can be described as diffusion enhanced (strongly, in the case of the outermost layer) with respect to the bulk, for both types of systems, despite its reduced dimensionality in metals. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0606/0606186v1.pdf"}
{"id": "cond-mat0606668", "abstract": "  Using the tight-binding method and the Landauer-Büttiker conductance formalism, we demonstrate that a multiply connected armchair carbon nanotube with a mirror-reflection symmetry can sustain an electron current of the π-bonding orbital while suppress that of the π-antibonding orbital over a certain energy range. Accordingly, the system behaves like an electron orbital valve and may be used as a scanning tunneling microscope to probe pairing symmetry in d-wave superconductors or even orbital ordering in solids which is believed to occur in some transition-metal oxides. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0606/0606668v2.pdf"}
{"id": "cond-mat0606819", "abstract": "  We present and study lattice and off-lattice microscopic models in which particles interact via a local anisotropic rule. The rule induces preferential hopping along one direction, so that a net current sets in if allowed by boundary conditions. This may be viewed as an oversimplification of the situation concerning certain traffic and flow problems. The emphasis in our study is on the influence of dynamic details on the resulting (non-equilibrium) steady state. In particular, we shall discuss on the similarities and differences between a lattice model and its continuous counterpart, namely, a Lennard-Jones analogue in which the particles' coordinates vary continuously. Our study, which involves a large series of computer simulations, in particular reveals that spatial discretization will often modify the resulting morphological properties and even induce a different phase diagram and criticality. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0606/0606819v1.pdf"}
{"id": "cond-mat0607074", "abstract": "  It is shown that additional contributions both to current-induced spin orientation and to the spin Hall effect arise in quantum wells due to gyrotropy of the structures. Microscopically, they are related to basic properties of gyrotropic systems, namely, linear in the wave vector terms in the matrix element of electron scattering and in the energy spectrum. Calculation shows that in high-mobility structures the contribution to the spin Hall current considered here can exceed the term originated from the Mott skew scattering. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0607/0607074v1.pdf"}
{"id": "cond-mat0607576", "abstract": "  The effects of space charges on hysteresis loops and field distributions in ferroelectrics have been investigated numerically using the phenomenological Landau-Ginzburg-Devonshire theory. Cases with the ferroelectric fully and partially depleted have been considered. In general, increasing the number of charged impurities results in a lowering of the polarization and coercive field values. Squarer loops were observed in the partially depleted cases and a method was proposed to identify fully depleted samples experimentally from dielectric and polarization measurements alone. Unusual field distributions found for higher dopant concentrations have some interesting implications for leakage mechanisms and limit the range of validity of usual semiconductor equations for carrier transport. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0607/0607576v1.pdf"}
{"id": "cond-mat0610397", "abstract": "  We review the properties of two coupled fermionic chains, or ladders, under a magnetic field parallel to the lattice plane. Results are computed by complementary analytical (bosonization) and numerical (density-matrix renormalization group) methods which allows a systematic comparison. Limiting cases such as coupled bands and coupled chains regimes are discussed. We particularly focus on the evolution of the superconducting correlations under increasing field and on the presence of irrational magnetization plateaus. We found the existence of large doping-dependent magnetization plateaus in the weakly-interacting and strong-coupling limits and in the non-trivial case of isotropic couplings. We report on the existence of extended Fulde-Ferrell-Larkin-Ovchinnikov phases within the isotropic t-J and Hubbard models, deduced from the evolution of different observables under magnetic field. Emphasis is put on the variety of superconducting order parameters present at high magnetic field. We have also computed the evolution of the Luttinger exponent corresponding to the ungaped spin mode appearing at finite magnetization. In the coupled chain regime, the possibility of having polarized triplet pairing under high field is predicted by bosonization. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0610/0610397v3.pdf"}
{"id": "cond-mat0611288", "abstract": "  We examine the spin current generated by quantum dots embedded in an optical microcavity. The dots are connected to leads, which allow electrons to tunnel into and out of the dot. The spin current is generated by spin flip transitions induced by a quantized electromagnetic field inside the cavity with one of the Zeeman states lying below the Fermi level of the leads and the other above. In the limit of strong Coulomb blockade, this model is analogous to the Jaynes-Cummings model in quantum optics. We find that the cavity field amplitude and the spin current exhibit bistability as a function of the laser amplitude, which is driving the cavity mode. Even in the limit of a single dot, the spin current and the Q distribution of the cavity field have a bimodal structure. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0611/0611288v3.pdf"}
{"id": "cond-mat0611616", "abstract": "  We demonstrate how to produce a stable multispeed lattice Boltzmann method (LBM) for a wide range of velocity sets, many of which were previously thought to be intrinsically unstable. We use non-Gauss–Hermitian cubatures. The method operates stably for almost zero viscosity, has second-order accuracy, suppresses typical spurious oscillation (only a modest Gibbs effect is present) and introduces no artificial viscosity. There is almost no computational cost for this innovation.   DISCLAIMER: Additional tests and wide discussion of this preprint show that the claimed property of coupled steps: no artificial dissipation and the second-order accuracy of the method are valid only on sufficiently fine grids. For coarse grids the higher-order terms destroy coupling of steps and additional dissipation appears.   The equations are true. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0611/0611616v3.pdf"}
{"id": "cond-mat0612696", "abstract": "  An understanding of the anomalous charge dynamics in the high-Tc cuprates is obtained based on a model study of doped Mott insulators. The high-temperature optical conductivity is found to generally have a two-component structure: a Drude like part followed by a mid-infrared band. The scattering rate associated with the Drude part exhibits a linear-temperature dependence over a wide range of high temperature, while the Drude term gets progressively suppressed below a characteristic energy of magnetic origin as the system enters the pseudogap phase. The high-energy optical conductivity shows a resonancelike feature in an underdoped case and continuously evolves into a 1/ωtail at higher doping, indicating that they share the same physical origin. In particular, such a high-energy component is closely correlated with the ω-peak structure of the density-density correlation function at different momenta, in systematic consistency with exact diagonalization results based on the t-J model. The underlying physics is attributed to the high-energy spin-charge separation in the model, in which the \"mode coupling\" responsible for the anomalous charge properties is not between the electrons and some collective mode but rather between new charge carriers, holons, and a novel topological gauge field controlled by spin dynamics, as the consequence of the strong short-range electron-electron Coulomb repulsion in the doped Mott insulator. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0612/0612696v2.pdf"}
{"id": "cond-mat0702428", "abstract": "  We analyse various phonon-assisted mechanisms which contribute to the decoherence of excitonic qubits in quantum dot systems coupled by the Förster-type transfer process. We show the significant loss of coherence accompanied by dissipation due to charge carrier oscillations between qubit states by using a model of one-phonon assisted Förster-type transfer process. We obtain explicit expressions for the relaxation and dephasing times for excitonic qubits interacting with acoustic phonons via both deformation potential and piezoelectric coupling. We compare the decoherence times of the GaAs/AlGaAs material system with half times of concurrence decay in a 2⊗2 bipartite mixed excitonic qubit system. We extend calculations to determine the influence of phonon mediated interactions on the non-unitary evolution of Berry phase in quantum dot systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0702/0702428v1.pdf"}
{"id": "cond-mat0702442", "abstract": "  The ground-state properties of spin polarized hydrogen H↓ are obtained by means of diffusion Monte Carlo calculations. Using the most accurate to date ab initio H↓-H↓ interatomic potential we have studied its gas phase, from the very dilute regime until densities above its freezing point. At very small densities, the equation of state of the gas is very well described in terms of the gas parameter ρ a^3, with a the s-wave scattering length. The solid phase has also been studied up to high pressures. The gas-solid phase transition occurs at a pressure of 173 bar, a much higher value than suggested by previous approximate descriptions. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0702/0702442v1.pdf"}
{"id": "cond-mat0703638", "abstract": "  We have numerically solved the Hamiltonian of an electron in a semiconductor double ring subjected to the magnetic flux and Rashba spin-orbit interaction. It is found that the Aharonov-Bohm energy spectrum reveals multi-zigzag periodic structures. The investigations of spin-dependent electron dynamics via Rabi oscillations in two-level and three-level systems demonstrate the possibility of manipulating quantum states. Our results show that the optimal control of photon-assisted inter-ring transitions can be achieved by employing cascade-type and Λ-type transition mechanisms. Under chirped pulse impulsions, a robust and complete transfer of an electron to the final state is shown to coincide with the estimation of the Landau-Zener formula. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0703/0703638v1.pdf"}
{"id": "cond-mat0703655", "abstract": "  Understanding radiation-induced defect formation in carbon materials is crucial for nuclear technology and for the manufacturing of nanostructures with desired properties. Using first principles molecular dynamics, we perform a systematic study of the non-equilibrium processes of radiation damage in graphite. Our study reveals a rich variety of defect structures (vacancies, interstitials, intimate interstitial-vacancy pairs, and in-plane topological defects) with formation energies of 5–15 eV. We clarify the mechanisms underlying their creation and find unexpected preferences for particular structures. Possibilities of controlled defect-assisted engineering of nanostructures are analyzed. In particular, we conclude that the selective creation of two distinct low-energy intimate Frenkel pair defects can be achieved by using a 90–110 keV electron beam irradiation. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0703/0703655v1.pdf"}
{"id": "cond-mat0703752", "abstract": "  When a superconducting tunnel junction at a finite voltage is irradiated with microwaves, the interplay between the alternating Josephson current and the ac field gives rise to steps in the dc current known as Shapiro steps. In this work we predict that in a mesoscopic structure connected to several superconducting terminals one can induce Shapiro-like steps in the absence of any external radiation simply by tuning the voltages of the leads. To illustrate this effect we make quantitative predictions for a three-terminal structure which comprises a diffusive superconductor-normal metal-superconductor junction and a tunneling probe, a set-up which can be realized experimentally. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0703/0703752v1.pdf"}
{"id": "cond-mat9501051", "abstract": "  A microscopic model of a surface polymer network - membrane system is introduced, with contact polymer surface interactions that can be either repulsive or attractive and sliplinks of functionality four randomly distributed over the supporting membrane surface anchoring the polymers to it. For the supporting surface perturbed from a planar configuration and a small relative number of surface sliplinks, we investigate an expansion of the free energy in terms of the local curvatures of the surface and the surface density of sliplinks, obtained through the application of the Balian - Bloch - Duplantier multiple surface scattering method. As a result, the dependence of the curvature elastic modulus, the Gaussian modulus as well as of the spontaneous curvature of the \"dressed\" membrane,  i.e. polymer network plus membrane matrix, is obtained on the mean polymer bulk end to end separation and the surface density of sliplinks. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9501/9501051v2.pdf"}
{"id": "cond-mat9509013", "abstract": "  Nonlinear magneto-optics is a very sensitive fingerprint of the electronic, magnetic, and atomic structure of surfaces, interfaces, and thin ferromagnetic films. Analyzing theoretically the nonlinear magneto-optical Kerr effect for thin films of Fe(001) and at Fe surfaces we demonstrate exemplarily how various electronic material properties of ferromagnets , such as the d-band width, the magnetization, the substrate lattice constant, and the film-thickness dependence can be extracted from the calculated nonlinear Kerr spectra. Furthermore, we show how the substrate d electrons (Cu(001)) affect the nonlinear Kerr spectra even without being themselves spin-polarized and without film-substrate hybridization. We show that the Kerr rotation angle in second harmonic generation is enhanced by one to two orders of magnitude compared to the linear Kerr angle and how symmetry can be used to obtain the direction of magnetization in thin films and at buried interfaces from nonlinear magneto-optics. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9509/9509013v1.pdf"}
{"id": "cond-mat9607203", "abstract": "  We show by numerical simulations that discretized versions of commonly studied continuum nonlinear growth equations (such as the Kardar-Parisi-Zhang equation and the Lai-Das Sarma equation) and related atomistic models of epitaxial growth have a generic instability in which isolated pillars (or grooves) on an otherwise flat interface grow in time when their height (or depth) exceeds a critical value. Depending on the details of the model, the instability found in the discretized version may or may not be present in the truly continuum growth equation, indicating that the behavior of discretized nonlinear growth equations may be very different from that of their continuum counterparts. This instability can be controlled either by the introduction of higher-order nonlinear terms with appropriate coefficients or by restricting the growth of pillars (or grooves) by other means. A number of such “controlled instability” models are studied by simulation. For appropriate choice of the parameters used for controlling the instability, these models exhibit intermittent behavior, characterized by multiexponent scaling of height fluctuations, over the time interval during which the instability is active. The behavior found in this regime is very similar to the “turbulent” behavior observed in recent simulations of several one- and two-dimensional atomistic models of epitaxial growth. [pacs61.50.Cj, 68.55.Bd, 05.70.Ln, 64.60.Ht] ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9607/9607203v1.pdf"}
{"id": "cond-mat9609248", "abstract": "  The Ginzburg-Landau (GL) equations for a d-wave superconductor are derived within the context of two microscopic lattice models used to describe the cuprates: the extended Hubbard model and the Antiferromagnetic-van Hove model. Both models have pairing on nearest-neighbour links, consistent with theories for d-wave superconductivity mediated by spin fluctuations. Analytical results obtained for the extended Hubbard model at low electron densities and weak-coupling are compared to results reported previously for a d-wave superconductor in the continuum. The variation of the coefficients in the GL equations with carrier density, temperature, and coupling constants are calculated numerically for both models. The relative importance of anisotropic higher-order terms in the GL free energy is investigated, and the implications for experimental observations of the vortex lattice are considered. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9609/9609248v1.pdf"}
{"id": "cond-mat9610046", "abstract": "  The formation energy of a solid surface can be extracted from slab calculations if the bulk energy per atom is known. It has been pointed out previously that the resulting surface energy will diverge with slab thickness if the bulk energy is in error, in the context of calculations which used different methods to study the bulk and slab systems. We show here that this result is equally relevant for state-of-the-art computational methods which carefully treat bulk and slab systems in the same way. Here we compare different approaches, and present a solution to the problem that eliminates the divergence and leads to rapidly convergent and accurate surface energies. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9610/9610046v1.pdf"}
{"id": "cond-mat9612139", "abstract": "  We employ a plaquette basis-generated by coupling the four spins in a 2×2 lattice to a well-defined total angular momentum-for the study of Heisenberg ladders with antiferromagnetic coupling. Matrix elements of the Hamiltonian in this basis are evaluated using standard techniques in angular-momentum (Racah) algebra. We show by exact diagonalization of small (2×4 and 2×6) systems that in excess of 90", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9612/9612139v1.pdf"}
{"id": "cond-mat9706117", "abstract": "  Three-dimensional icosahedral random tilings with rhombohedral cells are studied in the semi-entropic model. We introduce a global energy measure defined by the variance of the quasilattice points in the orthogonal space. The internal energy, the specific heat, the configuration entropy and the sheet magnetization (as defined by Dotera and Steinhardt [Phys.Rev.Lett. 72 (1994) 1670]) have been calculated. The specific heat shows a Schottky anomaly which might indicate a phase transition from an ordered quasicrystal to a random tiling. But the divergence with the sample size as well as the divergence of the susceptibility are too small to pinpoint the phase transition conclusively. The self-diffusion coefficients closely follow an Arrhenius law, but show plateaus at intermediate temperature ranges which are explained by energy barriers between different tiling configurations due to the harmonic energy measure. There exists a correlation between the temperature behavior of the self-diffusion coefficient and the frequency of vertices which are able to flip (simpletons). Furthermore we demonstrate that the radial distribution function and the radial structure factor only depend slightly on the random tiling configuration. Hence, radially symmetric pair potentials lead to an energetical equidistribution of all configurations of a canonical random tiling ensemble and do not enforce matching rules. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9706/9706117v1.pdf"}
{"id": "cond-mat9706289", "abstract": "  In order to shed light whether the `even-odd conjecture' (even numbers of legs will superconduct accompanied by a spin gap while odd ones do not) for correlated electrons in ladder systems, the pairing correlation is studied for the Hubbard model on a two- and three-leg ladders. We have employed both the weak-coupling renormalization group and the quantum Monte Carlo (QMC) method for strong interactions. For the two-leg Hubbard ladder, a systematic QMC (with a controlled level spacings) has detected an enhanced pairing correlation, which is consistent with the weak-coupling prediction. We also calculate the correlation functions in the three-leg Hubbard ladder and show that the weak-coupling study predicts the dominant superconductivity, which refutes the naive even-odd conjecture. A crucial point is a spin gap for only some of the multiple spin modes is enough to make the ladder superconduct with a pairing symmetry (d-like here) compatible with the gapped mode. A QMC study for the three-leg ladder endorses the enhanced pairing correlation. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9706/9706289v1.pdf"}
{"id": "cond-mat9706302", "abstract": "  Niobium thin film wires were fabricated using electron beam lithography with a four layer liftoff mask system, and subsequently thinned by anodisation. The resistance along the wire was monitored in situ and trimmed by controlling the anodisation voltage. Depending on the room temperature sheet resistance, samples showed either superconducting or insulating behaviour at low temperatures. A Coulomb blockade was observed for samples exceeding 6 kOhm per square. Samples were also made in a single electron transistor-like geometry with two weak links made by combined angular evaporation and anodisation. Their current-voltage characteristics could be modulated by a voltage applied to an overlapping gate. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9706/9706302v1.pdf"}
{"id": "cond-mat9708145", "abstract": "  We present a low-energy effective model for the charge degrees of freedom in two-leg t-J ladders. Starting from SU(2) mean-field theory, we exclude the spin degrees of freedom which have an energy gap. At low temperatures, the mean-field solution is the staggered-flux phase. For gapless charge excitations the effective theory is the Luther-Emery liquid. Our analysis is applicable at low doping and in the “physical” range of parameters t/J∼ 3 where there is only one massless mode in the charge sector and no massless modes in the spin sector. Within our model we make predictions about correlation exponents and the superconductivity order parameter, and discuss the comparison with the existing numerical results. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9708/9708145v1.pdf"}
{"id": "cond-mat9708208", "abstract": "  Recent experiments on the quasi 1-D antiferromagnet Cu Benzoate revealed a magentic field induced gap coexisting with (ferro)magnetic order. A theory explaining these findings has been proposed by Oshikawa and Affleck. In the present work we discuss consequences of this theory for inelastic neutron scattering experiments by calculating the dynamical magnetic susceptibilities close to the antiferromagnetic wave vector by the formfactor method. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9708/9708208v3.pdf"}
{"id": "cond-mat9710031", "abstract": "  Within a two-band tight binding model, we investigate the dynamics of electrons with Markoffian dephasing under the influence of static electric fields. With the help of both numerical and analytic calculations we find that the dephasing ultimately takes electrons which are initially located in one miniband to equal population of the two minibands, instead of undergoing persistent Rabi flop, as they do in the absence of scattering. Miniband localization is wholly destroyed by the intervention of dephasing. We also obtain the effective decay time for the approach to equal band populations under conditions of small interband communication and in the long-time limit, through a perturbative calculation. The decay rate shows characteristic sharp peaks at values of the parameters which give Zener resonances. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9710/9710031v1.pdf"}
{"id": "cond-mat9712088", "abstract": "  I calculate the effect of interactions among superconducting quasiparticles in two-dimensional(2D) a superconductor at T=0. The strength of the effective interaction among the quasiparticles is essentially given by the screened Coulomb interaction which has strength at low frequency because of the gapless nature of the plasmon. This is in contrast to three dimensions where the effective interaction has negligible weight at frequencies ∼Δ, the superconducting gap. The quasiparticle interactions give rise to strong-coupling effects in experimental quantities which are beyond the conventional Eliashberg treatment of superconductivity. The present calculation offers an explanation of why these effects are much larger in 2D than in 3D superconductors and, in particular, why the analogous strong-coupling effects due to quasiparticle interactions are seen in data on the quasi-2D cuprate superconductors. the strong-coupling features seen in data on the cuprates are discussed in light of the present calculation. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9712/9712088v1.pdf"}
{"id": "cond-mat9801292", "abstract": "  Lattice Boltzmann simulations are used to investigate spinodal decomposition in a two-dimensional binary fluid with equilibrium lamellar and droplet phases. We emphasise the importance of hydrodynamic flow to the phase separation kinetics. For mixtures slightly asymmetric in composition the fluid phase separates into bulk and lamellar phases with the lamellae forming distinctive spiral structures to minimise their elastic energy. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9801/9801292v1.pdf"}
{"id": "cond-mat9809423", "abstract": "  Many sedimentary rocks are formed by migration of sand ripples. Thin layers of coarse and fine sand are present in these rocks, and understanding how layers in sandstone are created has been a longstanding question. Here, we propose a mechanism for the origin of the most common layered sedimentary structures such as inverse graded climbing ripple lamination and cross-stratification patterns. The mechanism involves a competition between three segregation processes: (i) size-segregation and (ii) shape-segregation during transport and rolling, and (iii) size segregation due to different hopping lengths of the small and large grains. We develop a discrete model of grain dynamics which incorporates the coupling between moving grains and the static sand surface, as well as the different properties of grains, such as size and roughness, in order to test the plausibility of this physical mechanism. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9809/9809423v2.pdf"}
{"id": "cond-mat9812102", "abstract": "  Nanocrystalline metals, i.e. metals with grain sizes from 5 to 50 nm, display technologically interesting properties, such as dramatically increased hardness, increasing with decreasing grain size. Due to the small grain size, direct atomic-scale simulations of plastic deformation of these materials are possible, as such a polycrystalline system can be modeled with the computational resources available today.   We present molecular dynamics simulations of nanocrystalline copper with grain sizes up to 13 nm. Two different deformation mechanisms are active, one is deformation through the motion of dislocations, the other is sliding in the grain boundaries. At the grain sizes studied here the latter dominates, leading to a softening as the grain size is reduced. This implies that there is an “optimal” grain size, where the hardness is maximal.   Since the grain boundaries participate actively in the deformation, it is interesting to study the effects of introducing impurity atoms in the grain boundaries. We study how silver atoms in the grain boundaries influence the mechanical properties of nanocrystalline copper. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9812/9812102v1.pdf"}
{"id": "cond-mat9903425", "abstract": "  Domains and bubbles in tilted phases of Langmuir monolayers contain a class of textures knows as boojums. The boundaries of such domains and bubbles may display either cusp-like features or indentations. We derive analytic expressions for the textures within domains and surrounding bubbles, and for the shapes of the boundaries of these regions. The derivation is perturbative in the deviation of the bounding curve from a circle. This method is not expected to be accurate when the boundary suffers large distortions, but it does provide important clues with regard to the influence of various energetic terms on the order-parameter texture and the shape of the domain or bubble bounding curve. We also look into the effects of thermal fluctuations, which include a sample-size-dependent effective line tension. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9903/9903425v2.pdf"}
{"id": "cond-mat9904202", "abstract": "  Molecular dynamics simulations of a Xe monolayer sliding on Ag(001) and Ag(111) are carried out in order to ascertain the microscopic origin of friction. For several values of the electronic contribution to the friction of individual Xe atoms, the intra-overlayer phonon dissipation is calculated as a function of the corrugation amplitude of the substrate potential, which is a pertinent parameter to consider. Within the accuracy of the numerical results and the uncertainty with which the values of the relevant parameters are known at present, we conclude that electronic and phononic dissipation channels are of similar importance. While phonon friction gives rise to the rapid variation with coverage, the electronic friction provides a roughly coverage-independent contribution to the overall sliding friction. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9904/9904202v1.pdf"}
{"id": "cond-mat9906030", "abstract": "  In this paper we complete the study of the phase diagram and conformational states of a stiff homopolymer. It is known that folding of a sufficiently stiff chain results in formation of a torus. We find that the phase diagram obtained from the Gaussian variational treatment actually contains not one, but several distinct toroidal states distinguished by the winding number. Such states are separated by first order transition curves terminating in critical points at low values of the stiffness. These findings are further supported by off-lattice Monte Carlo simulation. Moreover, the simulation shows that the kinetics of folding of a stiff chain passes through various metastable states corresponding to hairpin conformations with abrupt U-turns. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9906/9906030v1.pdf"}
{"id": "cond-mat9906346", "abstract": "  We prove, by realistic microscopic calculations within the sp^3s^* Tight Binding method for GaAs (110) and (100), that the surface optical properties are not influenced by long-range crystal termination effects, and hence that they can be consistently studied considering slabs of limited thickness (20 - 30 Å). The origin of derivative-like and bulk-like lineshapes in Reflection Anisotropy Spectra is also discussed, analyzing the effects arising from possible surface-induced reduction, broadening, and shifting of the bulk spectrum near the surface. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9906/9906346v1.pdf"}
{"id": "cond-mat9907049", "abstract": "  The electronic quasiparticle spectrum of a ferromagnetic film is investigated within the framework of the s-f model. Starting from the exact solvable case of a single electron in an otherwise empty conduction band being exchange coupled to a ferromagnetically saturated localized spin system we extend the theory to finite temperatures. Our approach is a moment-conserving decoupling procedure for suitable defined Green functions. The theory for finite temperatures evolves continuously from the exact limiting case. The restriction to zero conduction band occupation may be regarded as a proper model description for ferromagnetic semiconductors like EuO and EuS. Evaluating the theory for a simple cubic film cut parallel to the (100) crystal plane, we find some marked correlation effects which depend on the spin of the test electron, on the exchange coupling, and on the temperature of the local-moment system. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9907/9907049v1.pdf"}
{"id": "cond-mat9908365", "abstract": "  The atomic pair distribution functions (PDF) of four powder samples of YBa2Cu3O6+x (x=0.25, 0.45, 0.65, 0.94) at 15 K have been measured by means of pulsed neutron diffraction. The PDF is modelled using a full-profile fitting approach to yield structural parameters. In contrast to earlier XAFS work we find no evidence of a split apical oxygen site. However, a slightly improved fit over the average crystallographic model results when the planar Cu(2) site is split along the z-direction. This is interpreted in terms of charge inhomogeneities in the CuO2 planes. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9908/9908365v2.pdf"}
{"id": "cond-mat9909105", "abstract": "  The spectra of Sinai microwave billiards and rectangular billiards with statistically distributed circular scatterers have been taken as a function of the position of one wall, and of one of the scatterers, respectively. Whereas in the first case the velocity distribution and correlations obey the universal behaviour predicted by Simons and Altshuler, in the second case a completely different behaviour is observed. This is due to the fact that a shift of one wall changes the wave function globally whereas the displacement of one scatterer only leads to a local perturbance. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9909/9909105v1.pdf"}
{"id": "cond-mat9909204", "abstract": "  We develop a practical method of computing the stationary drift velocity V and the diffusion coefficient D of a particle (or a few particles) in a periodic system with arbitrary transition rates. We solve this problem both in a physically relevant continuous-time approach as well as for models with discrete-time kinetics, which are often used in computer simulations. We show that both approaches yield the same value of the drift, but the difference between the diffusion coefficients obtained in each of them equals V*V/2. Generalization to spaces of arbitrary dimension and several applications of the method are also presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9909/9909204v1.pdf"}
{"id": "cond-mat9910147", "abstract": "  We numerically investigate the problem of the propagation of a shock in an horizontal non-loaded granular chain with a bead interaction force exponent varying from unity to large values. When α is close to unity we observed a cross-over between a nonlinearity-dominated regime and a solitonic one, the latest being the final steady state of the propagating wave. In the case of large values of α the deformation field given by the numerical simulations is completely different from the one obtained by analytical calculation. In the following we studied the interaction of these shock waves with a mass impurity placed in the bead chain. Two different physical pictures emerge whether we consider a light or a heavy impurity mass. The scatter of the shock wave with a light impurity yields damped oscillations of the impurity which then behave as a solitary wave source. Differently an heavy impurity is just shifted by the shock and the transmitted wave loses its solitonic character being fragmented into waves of decreasing amplitudes. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9910/9910147v1.pdf"}
{"id": "cs0209016", "abstract": "  A fork stack is a generalised stack which allows pushes and pops of several items at a time. We consider the problem of determining which input streams can be sorted using a single forkstack, or dually, which permutations of a fixed input stream can be produced using a single forkstack. An algorithm is given to solve the sorting problem and the minimal unsortable sequences are found. The results are extended to fork stacks where there are bounds on how many items can be pushed and popped at one time. In this context we also establish how to enumerate the collection of sortable sequences. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0209/0209016v1.pdf"}
{"id": "cs0310063", "abstract": "  We investigate mca-programs, that is, logic programs with clauses built of monotone cardinality atoms of the form kX, where k is a non-negative integer and X is a finite set of propositional atoms. We develop a theory of mca-programs. We demonstrate that the operational concept of the one-step provability operator generalizes to mca-programs, but the generalization involves nondeterminism. Our main results show that the formalism of mca-programs is a common generalization of (1) normal logic programming with its semantics of models, supported models and stable models, (2) logic programming with cardinality atoms and with the semantics of stable models, as defined by Niemela, Simons and Soininen, and (3) of disjunctive logic programming with the possible-model semantics of Sakama and Inoue. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0310/0310063v1.pdf"}
{"id": "cs0311025", "abstract": "  In this paper we describe our work on enabling fine-grained authorization for resource usage and management. We address the need of virtual organizations to enforce their own polices in addition to those of the resource owners, in regard to both resource consumption and job management. To implement this design, we propose changes and extensions to the Globus Toolkit's version 2 resource management mechanism. We describe the prototype and the policy language that we designed to express fine-grained policies, and we present an analysis of our solution. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0311/0311025v1.pdf"}
{"id": "cs0503060", "abstract": "  One-way hash chains have been used in many micropayment schemes due to their simplicity and efficiency. In this paper we introduce the notion of multi-dimensional hash chains, which is a new generalization of traditional one-way hash chains. We show that this construction has storage-computational complexity of O(logN) per chain element, which is comparable with the best result reported in recent literature. Based on multi-dimensional hash chains, we then propose two cash-like micropayment schemes, which have a number of advantages in terms of efficiency and security. We also point out some possible improvements to PayWord and similar schemes by using multi-dimensional hash chains ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0503/0503060v1.pdf"}
{"id": "cs0602069", "abstract": "  In this paper, we present a fast algorithm for constructing a concept (Galois) lattice of a binary relation, including computing all concepts and their lattice order. We also present two efficient variants of the algorithm, one for computing all concepts only, and one for constructing a frequent closed itemset lattice. The running time of our algorithms depends on the lattice structure and is faster than all other existing algorithms for these problems. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0602/0602069v2.pdf"}
{"id": "cs0605080", "abstract": "  Recent proposals in multicast overlay construction have demonstrated the importance of exploiting underlying network topology. However, these topology-aware proposals often rely on incremental and periodic refinements to improve the system performance. These approaches are therefore neither scalable, as they induce high communication cost due to refinement overhead, nor efficient because long convergence time is necessary to obtain a stabilized structure. In this paper, we propose a highly scalable locating algorithm that gradually directs newcomers to their a set of their closest nodes without inducing high overhead. On the basis of this locating process, we build a robust and scalable topology-aware clustered hierarchical overlay scheme, called LCC. We conducted both simulations and PlanetLab experiments to evaluate the performance of LCC. Results show that the locating process entails modest resources in terms of time and bandwidth. Moreover, LCC demonstrates promising performance to support large scale multicast applications. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0605/0605080v1.pdf"}
{"id": "cs0607095", "abstract": "  In this paper, we derive Gallager's random coding error exponent for multiple-input multiple-output (MIMO) channels, assuming no channel-state information (CSI) at the transmitter and perfect CSI at the receiver. This measure gives insight into a fundamental tradeoff between the communication reliability and information rate of MIMO channels, enabling to determine the required codeword length to achieve a prescribed error probability at a given rate below the channel capacity. We quantify the effects of the number of antennas, channel coherence time, and spatial fading correlation on the MIMO exponent. In addition, general formulae for the ergodic capacity and the cutoff rate in the presence of spatial correlation are deduced from the exponent expressions. These formulae are applicable to arbitrary structures of transmit and receive correlation, encompassing all the previously known results as special cases of our expressions. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0607/0607095v1.pdf"}
{"id": "cs0701140", "abstract": "  We propose an abstraction-based model checking method which relies on refinement of an under-approximation of the feasible behaviors of the system under analysis. The method preserves errors to safety properties, since all analyzed behaviors are feasible by definition. The method does not require an abstract transition relation to be generated, but instead executes the concrete transitions while storing abstract versions of the concrete states, as specified by a set of abstraction predicates. For each explored transition the method checks, with the help of a theorem prover, whether there is any loss of precision introduced by abstraction. The results of these checks are used to decide termination or to refine the abstraction by generating new abstraction predicates. If the (possibly infinite) concrete system under analysis has a finite bisimulation quotient, then the method is guaranteed to eventually explore an equivalent finite bisimilar structure. We illustrate the application of the approach for checking concurrent programs. ", "pdf_url": "gs://arxiv-dataset/arxiv/cs/pdf/0701/0701140v2.pdf"}
{"id": "gr-qc0006040", "abstract": "  As an example of a black hole in a non-flat background a composite static spacetime is constructed. It comprises a vacuum Schwarzschild spacetime for the interior of the black hole across whose horizon it is matched on to the spacetime of Vaidya representing a black hole in the background of the Einstein universe. The scale length of the exterior sets a maximum to the black hole mass. To obtain a non-singular exterior, the Vaidya metric is matched to an Einstein universe. The behaviour of scalar waves is studied in this composite model. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0006/0006040v2.pdf"}
{"id": "gr-qc0107076", "abstract": "  We perform a numerical study of the critical regime at the threshold of black hole formation in the spherically symmetric, general relativistic collapse of collisionless matter. The coupled Einstein-Vlasov equations are solved using a particle-mesh method in which the evolution of the phase-space distribution function is approximated by a set of particles (or, more precisely, infinitesimally thin shells) moving along geodesics of the spacetime. Individual particles may have non-zero angular momenta, but spherical symmetry dictates that the total angular momentum of the matter distribution vanish. In accord with previous work by Rein et al, our results indicate that the critical behavior in this model is Type I; that is, the smallest black hole in each parametrized family has a finite mass. We present evidence that the critical solutions are characterized by unstable, static spacetimes, with non-trivial distributions of radial momenta for the particles. As expected for Type I solutions, we also find power-law scaling relations for the lifetimes of near-critical configurations as a function of parameter-space distance from criticality. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0107/0107076v1.pdf"}
{"id": "gr-qc0111069", "abstract": "  The differential acceleration between a rotating mechanical gyroscope and a non-rotating one is directly measured by using a double free-fall interferometer, and no apparent differential acceleration has been observed at the relative level of 2x10-6. It means that the equivalence principle is still valid for rotating extended bodies, i.e., the spin-gravity interaction between the extended bodies has not been observed at this level. Also, to the limit of our experimental sensitivity, there is no observed asymmetrical effect or anti-gravity of the rotating gyroscopes as reported by hayasaka et al. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0111/0111069v1.pdf"}
{"id": "gr-qc0207073", "abstract": "  The Klein-Gordon-Einstein equations of classical real scalar fields have time-dependent solutions (periodic in time). We show that quantum real scalar fields can form non-oscillating (static) solitonic objects, which are quite similar to the solutions describing boson stars formed with classical and quantum complex scalar fields (the latter will be studied in this paper). We numerically analyze the difference between them concerning the mass of boson stars. On the other hand, we suggest an interesting test (a viable process that the boson star may undergo in the early universe) for the formation of boson stars. That is, it is questioned that after a second-order phase transition (a simple toy model will be considered here), what is the fate of the boson star composed of quantum real scalar field. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0207/0207073v2.pdf"}
{"id": "gr-qc0209036", "abstract": "  For the quantised, massless, minimally coupled real scalar field in four-dimensional Minkowski space, we show (by an explicit construction) that weighted averages of the null-contracted stress-energy tensor along null geodesics are unbounded from below on the class of Hadamard states. Thus there are no quantum inequalities along null geodesics in four-dimensional Minkowski spacetime. This is in contrast to the case for two-dimensional flat spacetime, where such inequalities do exist. We discuss in detail the properties of the quantum states used in our analysis, and also show that the renormalized expectation value of the stress energy tensor evaluated in these states satisfies the averaged null energy condition (as expected), despite the nonexistence of a null-averaged quantum inequality. However, we also show that in any globally hyperbolic spacetime the null-contracted stress energy averaged over a timelike worldline does satisfy a quantum inequality bound (for both massive and massless fields). We comment briefly on the implications of our results for singularity theorems. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0209/0209036v2.pdf"}
{"id": "gr-qc0212033", "abstract": "  We consider the application of the consistent lattice quantum gravity approach we introduced recently to the situation of a Friedmann cosmology and also to Bianchi cosmological models. This allows us to work out in detail the computations involved in the determination of the Lagrange multipliers that impose consistency, and the implications of this determination. It also allows us to study the removal of the Big Bang singularity. Different discretizations can be achieved depending on the version of the classical theory chosen as a starting point and their relationships studied. We analyze in some detail how the continuum limit arises in various models. In particular we notice how remnants of the symmetries of the continuum theory are embodied in constants of the motion of the consistent discrete theory. The unconstrained nature of the discrete theory allows the consistent introduction of a relational time in quantum cosmology, free from the usual conceptual problems. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0212/0212033v1.pdf"}
{"id": "gr-qc0212123", "abstract": "  The back reaction effect of the neutrino field at finite temperature in the background of the static Einstein universe is investigated. A relationship between the temperature of the universe and its radius is found. As in the previously studied cases of the massless scalar field and the photon field, this relation exhibit a minimum radius below which no self-consistent solution for the Einstein field equation can be found. A maximum temperature marks the transition from a vacuum dominated state to the radiation dominated state universe. In the light of the results obtained for the scalar, neutrino and photon fields the role of the back reaction of quantum fields in controling the value of the cosmological constant is briefly discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0212/0212123v2.pdf"}
{"id": "gr-qc0301104", "abstract": "  We study the scalar and spinor perturbation, namely the Klein-Gordan and Dirac equations, in the Kerr-NUT space-time. The metric is invariant under the duality transformation involving the exchange of mass and NUT parameters on one hand and radial and angle coordinates on the other. We show that this invariance is also shared by the scalar and spinor perturbation equations. Further, by the duality transformation, one can go from the Kerr to the dual Kerr solution, and vice versa, and the same applies to the perturbation equations. In particular, it turns out that the potential barriers felt by the incoming scalar and spinor fields are higher for the dual Kerr than that for the Kerr. We also comment on existence of horizon and singularity. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0301/0301104v2.pdf"}
{"id": "gr-qc0301105", "abstract": "  We present an exhaustive analysis of the numerical evolution of the Einstein-Klein-Gordon equations for the case of a real scalar field endowed with a quadratic self-interaction potential. The self-gravitating equilibrium configurations are called oscillatons and are close relatives of boson stars, their complex counterparts. Unlike boson stars, for which the oscillations of the two components of the complex scalar field are such that the spacetime geometry remains static, oscillatons give rise to a geometry that is time-dependent and oscillatory in nature. However, they can still be classified into stable (S-branch) and unstable (U-branch) cases. We have found that S-oscillatons are indeed stable configurations under small perturbations and typically migrate to other S-profiles when perturbed strongly. On the other hand, U-oscillatons are intrinsically unstable: they migrate to the S-branch if their mass is decreased and collapse to black holes if their mass is increased even by a small amount. The S-oscillatons can also be made to collapse to black holes if enough mass is added to them, but such collapse can be efficiently prevented by the gravitational cooling mechanism in the case of diluted oscillatons. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0301/0301105v1.pdf"}
{"id": "gr-qc0305031", "abstract": "  We analyze the weak gravity in the braneworld model proposed by Dvali-Gabadadze-Porrati, in which the unperturbed background spacetime is given by five dimensional Minkowski bulk with a brane which has the induced Einstein Hilbert term. This model has a critical length scale r_c. Naively, we expect that the four dimensional general relativity (4D GR) is approximately recovered at the scale below r_c. However, the simple linear perturbation does not work in this regime. Only recently the mechanism to recover 4D GR was clarified under the restriction to spherically symmetric configurations, and the leading correction to 4D GR was derived. Here, we develop an alternative formulation which can handle more general perturbations. We also generalize the model by adding bulk cosmological constant and the brane tension. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0305/0305031v2.pdf"}
{"id": "gr-qc0503090", "abstract": "  Our Universe may be a domain separated by physical phase boundaries from other domain-Universes with different vacuum energy density and matter content. The coexistence of different quantum vacua is perhaps regulated by the exchange of global fermionic charges or by fermion zero modes on the phase boundary. An example would be a static de-Sitter Universe embedded in an asymptotically flat spacetime. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0503/0503090v3.pdf"}
{"id": "gr-qc0602053", "abstract": "  This paper describes a multidimensional hydrodynamic code which can be used for the studies of relativistic astrophysical flows. The code solves the special relativistic hydrodynamic equations as a hyperbolic system of conservation laws based on High Resolution Shock Capturing (HRSC) Scheme. Two standard tests, one of which is the relativistic blast wave tested in our previous paper<cit.>, and the other is the collision of two ultrarelativistic blast waves tested in here, are presented to demonstrate that the code captures correctly and gives solution in the discontinuities, accurately.   The relativistic astrophysical jet is modeled for the ultrarelativistic flow case. The dynamics of jet flowing is then determined by the ambient parameters such as densities, and velocities of the jets and the momentum impulse applied to the computational surface. We obtain solutions for the jet structure, propagation of jet during the time evolution, and variation in the Mach number on the computational domain at a fixed time. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0602/0602053v1.pdf"}
{"id": "gr-qc0606096", "abstract": "  The cosmological constant Λ modifies certain properties of large astrophysical rotating configurations with ellipsoidal geometries, provided the objects are not too compact. Assuming an equilibrium configuration and so using the tensor virial equation with Λ we explore several equilibrium properties of homogeneous rotating ellipsoids. One shows that the bifurcation point, which in the oblate case distinguishes the Maclaurin ellipsoid from the Jacobi ellipsoid, is sensitive to the cosmological constant. Adding to that, the cosmological constant allows triaxial configurations of equilibrium rotating the minor axis as solutions of the virial equations. The significance of the result lies in the fact that minor axis rotation is indeed found in nature. Being impossible for the oblate case, it is permissible for prolate geometries, with Λ zero and positive. For the triaxial case, however, an equilibrium solution is found only for non-zero positive Λ. Finally, we solve the tensor virial equation for the angular velocity and display special effects of the cosmological constant there. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0606/0606096v2.pdf"}
{"id": "gr-qc0606097", "abstract": "  On the basis of the Kerr spinning particle, we show that the mass renormalization is perfectly performed by gravity for an arbitrary distribution of source matter. A smooth regularization of the Kerr-Newman solution is considered, leading to a source in the form of a rotating bag filled by a false vacuum. It is shown that gravity controls the phase transition to an AdS or dS false vacuum state inside the bag, providing the mass balance. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0606/0606097v1.pdf"}
{"id": "gr-qc0609042", "abstract": "  The Schwarzschild solution has played a fundamental conceptual role in general relativity, and beyond, for instance, regarding event horizons, spacetime singularities and aspects of quantum field theory in curved spacetimes. However, one still encounters the existence of misconceptions and a certain ambiguity inherent in the Schwarzschild solution in the literature. By taking into account the point of view of an observer in the interior of the event horizon, one verifies that new conceptual difficulties arise. In this work, besides providing a very brief pedagogical review, we further analyze the interior Schwarzschild black hole solution. Firstly, by deducing the interior metric by considering time-dependent metric coefficients, the interior region is analyzed without the prejudices inherited from the exterior geometry. We also pay close attention to several respective cosmological interpretations, and briefly address some of the difficulties associated to spacetime singularities. Secondly, we deduce the conserved quantities of null and timelike geodesics, and discuss several particular cases in some detail. Thirdly, we examine the Eddington-Finkelstein and Kruskal coordinates directly from the interior solution. In concluding, it is important to emphasize that the interior structure of realistic black holes has not been satisfactorily determined, and is still open to considerable debate. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0609/0609042v2.pdf"}
{"id": "gr-qc0612130", "abstract": "  The mirror relative motion of a suspended Fabry-Perot cavity is studied in the frequency range 3-10 Hz. The experimental measurements presented in this paper, have been performed at the Low Frequency Facility, a high finesse optical cavity 1 cm long suspended to a mechanical seismic isolation system identical to that one used in the VIRGO experiment. The measured relative displacement power spectrum is compatible with a system at thermal equilibrium within its environmental. In the frequency region above 3 Hz, where seismic noise contamination is negligible, the measurement distribution is stationary and Gaussian, as expected for a system at thermal equilibrium. Through a simple mechanical model it is shown that: applying the fluctuation dissipation theorem the measured power spectrum is reproduced below 90 Hz and noise induced by external sources are below the measurement. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0612/0612130v2.pdf"}
{"id": "gr-qc0702091", "abstract": "  In this article we study the influence of magnetic fields on the axial gravitational waves emitted during the collapse of a homogeneous dust sphere. We found that while the energy emitted depends weakly on the initial matter perturbations it has strong dependence on the strength and the distribution of the magnetic field perturbations. The gravitational wave output of such a collapse can be up to an order of magnitude larger or smaller calling for detailed numerical 3D studies of collapsing magnetized configurations. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0702/0702091v1.pdf"}
{"id": "gr-qc9508026", "abstract": "  We give a brief summary of results and ongoing research in the application of linearized theory to the study of black hole collisions in the limit in which the holes start close to each other. This approximation can be a valuable tool for comparison and code-checking of full numerical relativity computations. The approximation works quite well for the head-on case and this is motivation to pursue its use in other more interesting contexts. We summarize current efforts towards establishing the domain of validity of the approximation and its use in generation and evolution of initial data for more interesting physical cases. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/9508/9508026v1.pdf"}
{"id": "gr-qc9607029", "abstract": "  We assume that a self-gravitating thin string can be locally described by what we shall call a smoothed cone. If we impose a specific constraint on the model of the string, then its central line obeys the Nambu-Goto equations. If no constraint is added, then the worldsheet of the central line is a totally geodesic surface. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/9607/9607029v2.pdf"}
{"id": "gr-qc9807047", "abstract": "  We present results from a new technique which allows extraction of gravitational radiation information from a generic three-dimensional numerical relativity code and provides stable outer boundary conditions. In our approach we match the solution of a Cauchy evolution of the nonlinear Einstein field equations to a set of one-dimensional linear equations obtained through perturbation techniques over a curved background. We discuss the validity of this approach in the case of linear and mildly nonlinear gravitational waves and show how a numerical module developed for this purpose is able to provide an accurate and numerically convergent description of the gravitational wave propagation and a stable numerical evolution. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/9807/9807047v1.pdf"}
{"id": "gr-qc9811029", "abstract": "  The gravitational back-reaction is calculated for the conformally invariant scalar field within a black cosmic string interior with cosmological constant. Using the perturbed metric, the gravitational effects of the quantum field are calculated. It is found that the perturbations initially strengthen the singularity. This effect is similar to the case of spherical symmetry (without cosmological constant). This indicates that the behaviour of quantum effects may be universal and not dependent on the geometry of the spacetime nor the presence of a non-zero cosmological constant. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/9811/9811029v3.pdf"}
{"id": "gr-qc9912027", "abstract": "  The main theoretical aspects of gravitomagnetism are reviewed. It is shown that the gravitomagnetic precession of a gyroscope is intimately connected with the special temporal structure around a rotating mass that is revealed by the gravitomagnetic clock effect. This remarkable effect, which involves the difference in the proper periods of a standard clock in prograde and retrograde circular geodesic orbits around a rotating mass, is discussed in detail. The implications of this effect for the notion of “inertial dragging” in the general theory of relativity are presented. The theory of the clock effect is developed within the PPN framework and the possibility of measuring it via spaceborne clocks is examined. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/9912/9912027v1.pdf"}
{"id": "hep-ex0002044", "abstract": "  The design, construction and performance of the H1 silicon vertex detector is described. It consists of two cylindrical layers of double sided, double metal silicon sensors read out by a custom designed analog pipeline chip. The analog signals are transmitted by optical fibers to a custom designed ADC board and are reduced on PowerPC processors. Details of the design and construction are given and performance figures from the first data taking periods are presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ex/pdf/0002/0002044v1.pdf"}
{"id": "hep-ex0007024", "abstract": "  Higgs hunting is a world-wide sport and the Tevatron is set to become the next field of play when Run II starts in March 2001. To set the stage, we summarize results of searches for standard and non-standard Higgs bosons by CDF and Dzero in Run I at the Tevatron. Progress has been made in quantifying the requirements on the Tevatron Collider and on the upgraded experiments in Run II for extending the excellent work done at LEP. Armed with parameterizations of expected detector performance, the Tevatron Higgs Working group has made predictions of the sensitivity of CDF and Dzero to Higgs bosons in the Standard Model and in its Minimal Supersymmetric extension as a function of integrated luminosity. These predictions are presented to underscore the excitement being generated by Run II, and to highlight the need for the highest possible luminosity. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ex/pdf/0007/0007024v1.pdf"}
{"id": "hep-ex9806003", "abstract": "  Dedicated experiments searching for lepton flavour violation can be performed very sensitively using K-decays and μ-decays as well as neutrinoless double β-decay and muonium to antimuonium conversion. Although there is no confirmed signal reported yet, stringent limits for parameters in speculative extensions to the standard model can be set. Some models could recently be ruled out. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ex/pdf/9806/9806003v3.pdf"}
{"id": "hep-lat0009002", "abstract": "  We investigate the eigenvalue spectrum of the staggered Dirac matrix in SU(3) gauge theory and in full QCD as well as in quenched U(1) theory. As a measure of the fluctuation properties of the eigenvalues, we consider the nearest-neighbor spacing distribution. We find that in all regions of their phase diagrams, compact lattice gauge theories have bulk spectral correlations given by random matrix theory, which is an indication for quantum chaos. In the confinement phase, the low-lying Dirac spectrum of these quantum field theories is well described by random matrix theory, exhibiting universal behavior. Related results for gauge theories with minimal coupling are now discussed also in the chirally symmetric phase. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/0009/0009002v1.pdf"}
{"id": "hep-lat0205027", "abstract": "  We consider the SU(2) lattice gauge model and investigate numerically the continuum limit of the simple center vortices which are singular configurations of the gauge fields. We found that the vortices remain alive in the continuum theory. Also we investigate the Creutz ratio and found that for all β it vanishes for those field configurations which do not contain the simple center vortices inside the considered Wilson loop. It leads us to the conclusion that these singular field configurations play a real role in the continuum theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/0205/0205027v2.pdf"}
{"id": "hep-lat0410037", "abstract": "  We present a calculation of the magnetic moments of the baryon octet and decuplet using the external field method and standard Wilson gauge and fermion actions in the quenched approximation. Progressively smaller static magnetic fields are introduced on a 24^4 latticeat beta=6.0 and the pion mass is probed down to about 500 MeV. Magnetic moments are extracted from the linear response of the masses to the external field. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/0410/0410037v1.pdf"}
{"id": "hep-lat0411034", "abstract": "  Our study on the cut-off effects in quenched light hadron spectroscopy and pion scattering length with the fixed point action is extended by results obtained at a lattice spacing a=0.102 fm in a box of size L=1.8 fm. The cut-off effects are small, but clearly seen as the resolution is increased from a=0.153 fm to a=0.102 fm. In the quark mass region where the errors are small and under control, our results on the APE plot lie close to the extrapolated numbers of the CP-PACS Collaboration. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/0411/0411034v2.pdf"}
{"id": "hep-lat0501023", "abstract": "  We discuss the weak coupling expansion of a one plaquette SU(2) lattice gauge theory. We show that the conventional perturbative series for the partition function has a zero radius of convergence and is asymptotic. The average plaquette is discontinuous at g^2=0. However, the fact that SU(2) is compact provides a perturbative sum that converges toward the correct answer for positive g^2. This alternate methods amounts to introducing a specific coupling dependent field cut, that turns the coefficients into g-dependent quantities. Generalizing to an arbitrary field cut, we obtain a regular power series with a finite radius of convergence. At any order in the modified perturbative procedure, and for a given coupling, it is possible to find at least one (and sometimes two) values of the field cut that provide the exact answer. This optimal field cut can be determined approximately using the strong coupling expansion. This allows us to interpolate accurately between the weak and strong coupling regions. We discuss the extension of the method to lattice gauge theory on a D-dimensional cubic lattice. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/0501/0501023v2.pdf"}
{"id": "hep-lat9507019", "abstract": "  We calculate within a mean-field approximation the slopes of the critical lines near the point of appearing the ferrimagnetic phase for the U(1) systems in the weak coupling regime. It is demonstrated that the slope of one of the critical line is continuous, while change of the slope of the other depends strongly on the number of the fermion flavours. We also find that in the ferrimagnetic phase near such a point the magnetization and the staggered magnetization align orthogonally to each other. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/9507/9507019v1.pdf"}
{"id": "hep-ph0002212", "abstract": "  The dynamical fermion mass generation in the 4-dimensional brane is discussed in a model with 5-dimensional Kaluza-Klein fermions in interaction with 4-dimensional fermions. It is found that the dynamical fermion masses are generated beyond the critical radius of the compactified extra dimensional space and may be made small compared with masses of the Kaluza-Klein modes. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0002/0002212v2.pdf"}
{"id": "hep-ph0005165", "abstract": "  Transverse momentum spectra of the reaction products from proton-proton and nucleus-nucleus collisions are discussed within the phenomenological frameworks of statistical phase-space and string fragmentation models. It will be shown that a string fragmentation model can accommodate all of the observations discussed here and consequently it is claimed that no conclusion about the thermal nature or collective expansion of the created system may be derived from observed transverse momentum spectra. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0005/0005165v1.pdf"}
{"id": "hep-ph0006221", "abstract": "  A critical review is presented of the attempts to estimate the Strong Interactions contributions to the parameter S (L_10 in the QCD Chiral Version). In particular it is discussed why the estimations done for Technicolor are unreliable. S is calculated for heavy doublets of Techniquarks using the Nonrelativistic Quark Model and keeping v≃ 0.25 TeV fixed. It is found that heavy Techniquarks decouple, so it is possible to obtain values for S in agreement with present experimental data. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0006/0006221v3.pdf"}
{"id": "hep-ph0101118", "abstract": "  We present calculations of the charming-penguin long-distance contributions to B => K πdecays due to intermediate charmed meson states. Our calculation is based on the Chiral Effective Lagrangean for light and heavy mesons, corrected for the hard pion and kaon momenta. We find that the charming-penguin contributions increase significantly the B => K πdecay rates in comparison with the short-distance contributions, giving results in better agreement with experimental data. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0101/0101118v2.pdf"}
{"id": "hep-ph0101148", "abstract": "  I discuss in this talk mainly three topics related with dark matter motivated neutrino mass spectrum and a generic issue of mass pattern, the normal versus the inverted mass hierarchies. In the first part, by describing failure of a nontrivial potential counter example, I argue that the standard 3 ν mixing scheme with the solar and the atmospheric Δ m^2's is robust. In the second part, I discuss the almost degenerate neutrino (ADN) scenario as the unique possibility of accommodating dark matter mass neutrinos into the 3 ν scheme. I review a cosmological bound and then reanalyze the constraints imposed on the ADN scenario with the new data of double beta decay experiment. In the last part, I discuss the 3 ν flavor transformation in supernova (SN) and point out the possibility that neutrinos from SN may distinguish the normal versus inverted hierarchies of neutrino masses. By analyzing the neutrino data from SN1987A, I argue that the inverted mass hierarchy is disfavored by the data. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0101/0101148v1.pdf"}
{"id": "hep-ph0101278", "abstract": "  In the model of Arkani-Hamed and Schmaltz the various chiral fermions of the Standard Model(SM) are localized at different points on a thick wall which forms an extra dimension. Such a scenario provides a way of understanding the absence of proton decay and the fermion mass hierarchy in models with extra dimensions. In this paper we explore the capability of future lepton colliders to determine the location of these fermions in the extra dimension through precision measurements of conventional scattering processes both below and on top of the lowest lying Kaluza-Klein gauge boson resonance. We show that for some classes of models the locations of these fermions can be very precisely determined while in others only their relative positions can be well measured. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0101/0101278v1.pdf"}
{"id": "hep-ph0102249", "abstract": "  The road towards unification of elementary interactions is thought to start on the solid ground of a universal local gauge principle. I discuss the different types of bosonic gauge symmetries in gravitational and nongravitational (standard model) interactions and their extensions both fermionic, bosonic and with respect to space-time dimensions. The apparently paradoxical size and nature of the cosmological constant is sketched, which at first sight does not readily yield a clue as to the envelopping symmetry structure of a unified theory. Nevertheless a tentative outlook is given encouraging to proceed on this road. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0102/0102249v2.pdf"}
{"id": "hep-ph0109105", "abstract": "  We obtain positronium Hyperfine Splitting owing to the non-commutativity of space and show that, in the leading order, it is proportional to θα^6 where, θ is the parameter of non-commutativity. It is also shown that spatial non-commutativity splits the spacing between n=2 triplet excited levels E(2^3S_1)→ E(2^3P_2) which provides an experimental test on the non-commutativity of space. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0109/0109105v2.pdf"}
{"id": "hep-ph0110339", "abstract": "  The photon plus missing energy signature is a primary handle on two important classes of theories. Theories with large extra dimensions predict the production of photons in association with Kaluza-Klein excitations of the graviton. In supersymmetric theories with superlight gravitinos, photons can be produced in association with gravitino pairs. The signatures for these two theories are compared, and it is found that they can be distinguished by studying the photon energy distributions and scaling of the cross section with center-of-mass energy. Both these methods fail, however, if there are six extra dimensions. In that case, additional phenomena predicted by the theories would be required to narrow down the underlying causes of the photon plus missing energy signal. We also study the ability of these measurements to determine the number of extra dimensions. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0110/0110339v1.pdf"}
{"id": "hep-ph0201217", "abstract": "  Mass spectra of baryons consisting of two heavy (b or c) and one light quarks are calculated in the framework of the relativistic quark model. The light quark-heavy diquark structure of the baryon is assumed. Under this assumption the ground and excited states of both the diquark and quark-diquark bound system are considered. The quark-diquark potential is constructed. The light quark is treated completely relativistically, while the expansion in the inverse heavy quark mass is used revealing the close similarity with the mass spectra of B and D mesons. We find that the relativistic treatment of the light quark plays an important role. The level inversion of the p-wave excitations of the light quark in doubly heavy baryons is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0201/0201217v1.pdf"}
{"id": "hep-ph0207159", "abstract": "  Production of electroweak bosons in e+e- annihilation into quarks and into leptons at energies much greater than 100 Gev is considered. We account for double-logarithmic contributions to all orders in electroweak couplings. It is assumed that the bosons are emitted in the multi-Regge kinematics. The explicit expressions for the scattering amplitudes of the process are obtained. It is shown that the cross sections of the photon and Z production have the identical energy dependence and asymptotically their ratio depends only on the Weinberg angle whereas the energy dependence of the cross section of the W production is suppressed by factor s^-0.4 compared to them. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0207/0207159v1.pdf"}
{"id": "hep-ph0209196", "abstract": "  The neutrino-electron scattering in a dense degenerate magnetized plasma under the conditions μ^2 > 2eB ≫μ E is investigated.   The volume density of the neutrino energy and momentum losses due to this process are calculated. The results we have obtained demonstrate that plasma in the presence of an external magnetic field is more transparent for neutrino than non-magnetized plasma. It is shown that neutrino scattering under conditions considered does not lead to the neutrino force acting on plasma. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0209/0209196v1.pdf"}
{"id": "hep-ph0210086", "abstract": "  We calculate radiative corrections to the masses of the Higgs bosons in a minimal supersymmetric model that contains an additional non-anomalous (U(1)') gauge symmetry. With some fine-tuning of the (U(1)') charges of the Higgs fields, it is possible to suppress the (Z)–(Z^') mixing. We use this fact, along with the lower bound on the lightest Higgs mass after LEPII era, as a criterion to restrict the set of parameters in our analysis. We calculate the mass of the lightest Higgs and its mixing with the other Higgs bosons, in a large region of the parameter space. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0210/0210086v3.pdf"}
{"id": "hep-ph0210337", "abstract": "  Using a simple Asymptotically Strong N=1 Susy SU(2) Gauge theory coupled to a 5-plet Chiral superfield we demonstrate the plausibility of the “ truly minimal ” Asymptotically Strong Grand Unification scenario proposed by us recently. Assuming a dynamical superpotential consistent with the symmetries and anomalies is actually induced non-perturbatively we show the gauge symmetry is dynamically and spontaneously broken at a UV scale that is generically exponentially larger than the scales characteristic of the effective low energy theory. The pattern of condensates in a semi-realistic SU(5) ASGUT is analyzed using the Konishi anomaly assuming condensation occurs as shown by our toy model. The necessarily complementary relation of ASGUTs to the Dual Unification program and the novel cosmogony implied by their unusual thermodynamic properties are also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0210/0210337v1.pdf"}
{"id": "hep-ph0212028", "abstract": "  We study unification in the Randall-Sundrum scenario for solving the hierarchy problem, with gauge fields and fermions in the bulk. We calculate the one-loop corrected low-energy effective gauge couplings in a unified theory, broken at the scale M_GUT in the bulk. We find that, although this scenario has an extra dimension, there is a robust (calculable in the effective field theory) logarithmic dependence on M_GUT, strongly suggestive of high-scale unification, very much as in the (4D) Standard Model. Moreover, bulk threshold effects are naturally small, but volume-enhanced, so that we can accommodate the measured gauge couplings. We show in detail how excessive proton decay is forbidden by an extra U(1) bulk gauge symmetry. This mechanism requires us to further break the unified group using boundary conditions. A 4D dual interpretation, in the sense of the AdS/CFT correspondence, is provided for all our results. Our results show that an attractive unification mechanism can combine with a non-supersymmetric solution to the hierarchy problem. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0212/0212028v2.pdf"}
{"id": "hep-ph0212396", "abstract": "  A possibility to prove spin and CP-eigenvalue of a Standard Model (SM) Higgs boson is presented. We exploit angular correlations in the subsequent decay H -> ZZ -> 4l (muons or electrons) for Higgs masses above 200 GeV. We compare the angular distributions of the leptons originating from the SM Higgs with those resulting from decays of hypothetical particles with differing quantum numbers. We restrict our analysis to the use of the Atlas-detector which is one of two multi-purpose detectors at the upcoming 14 TeV proton-proton-collider (LHC) at CERN. By applying a fast simulation of the Atlas detector it can be shown that these correlations will be measured sufficiently well that consistency with the spin-CP hypothesis 0+ of the Standard Model can be verified and the 0- and 1+- can be ruled out with an integrated luminosity of 100 fb^-1. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0212/0212396v2.pdf"}
{"id": "hep-ph0303252", "abstract": "  We propose a two-zero-texture general Zee model, compatible with the large mixing angle Mikheyev-Smirnov-Wolfenstein solution. The washing out of the baryon number does not occur in this model for an adequate parameter range. We check the consistency of a model with the constraints coming from flavor changing neutral current processes, the recent cosmic microwave background observation, and the Z-burst scenario. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0303/0303252v4.pdf"}
{"id": "hep-ph0304141", "abstract": "  We extend the minimal supersymmetric standard model with bilinear R-parity violation to include a pair of Higgs triplet superfields. The neutral components of the Higgs triplets develop small vacuum expectation values (VEVs) quadratic in the bilinear R-parity breaking parameters. In this scheme the atmospheric neutrino mass scale arises from bilinear R-parity breaking while for reasonable values of parameters the solar neutrino mass scale is generated from the small Higgs triplet VEVs. We calculate neutrino masses and mixing angles in this model and show how the model can be tested at future colliders. The branching ratios of the doubly charged triplet decays are related to the solar neutrino angle via a simple formula. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0304/0304141v3.pdf"}
{"id": "hep-ph0307082", "abstract": "  I give a very short introduction to Chiral Perturbation Theory and an overview of the next-to-next-to-leading order three-flavour calculations done. I discuss those relevant for an improvement in the accuracy of the measurement of V_us in more detail. One major conclusion is that all needed p^6 low energy constants can be obtained from experiment via the scalar form-factor in K_ℓ3 decays. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0307/0307082v1.pdf"}
{"id": "hep-ph0307222", "abstract": "  A liquid Argon TPC (ICARUS-like) has the ability to detect neutrino bursts from type-II supernova collapses, via three processes: elastic scattering by electrons from all neutrino species, and ν_e charged current absorption on Ar with production of excited K and ν̅_e charged current absorption on Ar with production of excited Cl. In this paper we have used new calculations in the random phase approximation (RPA) for the absorption processes. The anti-neutrino reaction ν̅_e ^40Ar absorption has been considered for the first time. For definiteness, we compute rates for the 3 kton ICARUS detector: 244 events are expected from a supernova at a distance of 10 kpc, without considering oscillation effects. The impact of oscillations in the neutrino rates will be discussed in a separate paper. We also discuss the ability to determine the direction of the supernova. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0307/0307222v1.pdf"}
{"id": "hep-ph0403002", "abstract": "  The NLO-QCD correction to single hadron production in deep inelastic scattering is calculated. We require the final state meson to carry a non-vanishing transversal momentum, thus being sensitive to perturbative QCD effects. Factorization allows us to convolute the hard scattering process with parton densities and fragmentation functions. The predictions are directly comparable to experimental results at the HERA collider at DESY. The results are sensitive to the gluon density in the proton and allow us to test universality of fragmentation functions. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0403/0403002v1.pdf"}
{"id": "hep-ph0408095", "abstract": "  We extract the next-to-next-to-leading order results for spin-flip generalized polarizabilities (GPs) of the nucleon from the spin-dependent amplitudes for virtual Compton scattering (VCS) at O(p^4) in heavy baryon chiral perturbation theory. At this order, no unknown low energy constants enter the theory, allowing us to make absolute predictions for all spin-flip GPs. Furthermore, by using constraint equations between the GPs due to nucleon crossing combined with charge conjugation symmetry of the VCS amplitudes, we get a next-to-next-to-next-to-leading order prediction for one of the GPs. We provide estimates for forthcoming double polarization experiments which allow to access these spin-flip GPs of the nucleon. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0408/0408095v1.pdf"}
{"id": "hep-ph0408303", "abstract": "  A comparative study of commonly used hadronic collision simulation packages is presented. The characteristics of the products of hadron-nucleus collisions are analyzed from a general perspective, but focusing on their correlation with diffractive processes. One of the purposes of our work is to give quantitative estimations of the impact that different characteristics of the hadronic models have on air shower observables. Several sets of shower simulations using different settings for the parameters controlling the diffractive processes are used to analyze the correlations between diffractivity and shower observables. We find that the relative probability of diffractive processes during the shower development have a non negligible influence over the longitudinal profile as well as the distribution of muons at ground level. The implications on experimental data analysis are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0408/0408303v3.pdf"}
{"id": "hep-ph0409234", "abstract": "  We study a class of nonperturbative corrections to single-inclusive photon cross sections at measured transverse momentum p_T, in the large-x_T limit. We develop an extension of the joint (threshold and transverse momentum) resummation formalism, appropriate for large x_T, in which there are no kinematic singularities associated with recoil, and for which matching to fixed order and to threshold resummation at next-to-leading logarithm (NLL) is straightforward. Beyond NLL, we find contributions that can be attributed to recoil from initial state radiation. Associated power corrections occur as inverse powers of p_T^2 and are identified from the infrared structure of integrals over the running coupling. They have significant energy dependence and decrease from typical fixed-target to collider energies. Energy conservation, which is incorporated into joint resummation, moderates the effects of perturbative recoil and power corrections for large x_T. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0409/0409234v2.pdf"}
{"id": "hep-ph0410247", "abstract": "  We provide a simple but robust argument that primordial black hole (PBH) production generically does not exceed astrophysical bounds during the resonant preheating phase after inflation. This conclusion is supported by fully nonlinear lattice simulations of various models in two and three dimensions which include rescattering but neglect metric perturbations. We examine the degree to which preheating amplifies density perturbations at the Hubble scale and show that at the end of the parametric resonance, power spectra are universal, with no memory of the power spectrum at the end of inflation. In addition we show how the probability distribution of density perturbations changes from exponential on very small scales to Gaussian when smoothed over the Hubble scale – the crucial length for studies of primordial black hole formation – hence justifying the standard assumption of Gaussianity. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0410/0410247v2.pdf"}
{"id": "hep-ph0410344", "abstract": "  We analyze the behavior of Standard Model matter propagating in a slice of AdS_5 in the presence of infrared-brane kinetic terms. Brane kinetic terms are naturally generated through radiative corrections and can also be present at tree level. The effect of the brane kinetic terms is to expell the heavy KK modes from the infrared-brane, and hence to reduce their coupling to the localized Higgs field. In a previous work we showed that sizable gauge kinetic terms can allow KK mode masses as low as a few TeV, compatible with present precision measurements. We study here the effect of fermion brane kinetic terms and show that they ameliorate the behavior of the theory for third generation fermions localized away from the infrared brane, reduce the contribution of the third generation quarks to the oblique correction parameters and mantain a good fit to the precision electroweak data for values of the KK masses of the order of the weak scale. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0410/0410344v1.pdf"}
{"id": "hep-ph0502048", "abstract": "  We investigate brane world models in higher-derivative gravity theories where the gravitational Lagrangian is an arbitrary function of the Ricci scalar. Making use of the conformal equivalence of such gravity models and Einstein-Hilbert gravity with a scalar field, we deduce the main features of higher-derivative gravity brane worlds. We solve for a gravity model that has corrections quadratic in the Ricci scalar and show one can evade both fine-tuning and the need for a bulk cosmological constant. An analysis of tensor and scalar perturbations shows gravity is localized on the brane and we recover the Newtonian limit. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0502/0502048v1.pdf"}
{"id": "hep-ph0502250", "abstract": "  We consider the intersection of N different interfaces interpolating between different Z_N vacua of an SU(N) gauge theory using the Polyakov loop order parameter. Topological arguments show that at such a string-like junction, the order parameter should vanish, implying that the core of this string (i.e. the junction region of all the interfaces) is in the confining phase. Using the effective potential for the Polyakov loop proposed by Pisarski for QCD, we use numerical minimization technique and estimate the energy per unit length of the core of this string to be about 2.7 GeV/fm at a temperature about twice the critical temperature. For the parameters used, the interface tension is obtained to be about 7 GeV/fm^2. Lattice simulation of pure gauge theories should be able to investigate properties of these strings. For QCD with quarks, it has been discussed in the literature that this Z_N symmetry may still be meaningful, with quark contributions leading to explicit breaking of this Z_N symmetry. With this interpretation, such QGP strings may play important role in the evolution of the quark-gluon plasma phase and in the dynamics of quark-hadron transition. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0502/0502250v1.pdf"}
{"id": "hep-ph0506162", "abstract": "  A number of promising results of a new 3+1 dimensional Monte Carlo parton cascade including inelastic multiplication processes (gg <–> ggg) are elaborated: (1) thermalization and chemical saturation; (2) the onset of longitudinal hydrodynamical expansion; (3) the build up of elliptic flow. We first briefly outline the basic idea of the algorithm. Full simulations are done with initial conditions for the kinetic partons via minijets or with ones stemming from a color glass condensate. The inclusion of the inelastic channels leads to a very fast kinetic equilibration and also to an early creation of pressure. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0506/0506162v1.pdf"}
{"id": "hep-ph0509317", "abstract": "  A general analysis of Meissner effect and spin susceptibility of a uniform superconductor in an asymmetric two-component fermion system is presented in nonrelativistic field theory approach. We found that, the pairing mechanism dominates the magnetization property of superconductivity, and the asymmetry enhances the paramagnetism of the system. At the turning point from BCS to breached pairing superconductivity, the Meissner mass squared and spin susceptibility are divergent at zero temperature. In the breached pairing state induced by chemical potential difference and mass difference between the two kinds of fermions, the system goes from paramagnetism to diamagnetism, when the mass ratio of the two species increases. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0509/0509317v3.pdf"}
{"id": "hep-ph0509356", "abstract": "  We demonstrate that the effects of matter upon neutrino propagation may be recast as the scattering of the initial neutrino wavefunction. Exchanging the differential, Schrodinger equation for an integral equation for the scattering matrix S permits a Monte Carlo method for the computation of S that removes many of the numerical difficulties associated with direct integration techniques. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0509/0509356v1.pdf"}
{"id": "hep-ph0512169", "abstract": "  We analyze flavor constraints in the littlest Higgs model with T-parity. In particular, we focus on neutral meson mixing in the K, B, and D systems due to one loop contributions from T-parity odd fermions and gauge bosons. We calculate the short distance contributions to mixing for a general choice of T-odd fermion Yukawa couplings. We find that for a generic choice of textures, a TeV scale GIM suppression is necessary to avoid large contributions. If order one mixing angles are allowed in the extended flavor structure, the mass spectrum is severely constrained, and must be degenerate at the 1-5", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0512/0512169v1.pdf"}
{"id": "hep-ph0602019", "abstract": "  The experimental test problem of the left-right polarization-dependent lifetime asymmetry is discussed. It shows that the existing experiments cannot demonstrate the lifetime asymmetry to be right or wrong after analyzing the measurements on the neutron, the muon and the tau lifetime, as well as the g-2 experiment. However, It is pointed out emphatically that the SLD and the E158 experiments, the measurements of the left-right integrated cross section asymmetry in Z boson production by e^+e^- collisions and by electron-electron Møller scattering, can indirectly demonstrate the lifetime asymmetry. In order to directly demonstrate the lifetime asymmetry, we propose some possible experiments on the decays of polarized muons. The precise measurement of the lifetime asymmetry could have important significance for building a muon collider, also in cosmology and astrophysics. It would provide a sensitive test of the standard model in particle physics and allow for exploration of the possible V+A interactions. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0602/0602019v3.pdf"}
{"id": "hep-ph0604230", "abstract": "  I will begin by making a few general comments on the synergy between the Large Hadron Collider (LHC) which will go in action in 2007 and the International Linear Collider (ILC) which is under planning. I will then focus on the synergy between the LHC and the PLC option at the ILC, which is expected to be realised in the later stages of the ILC program. In this I will cover the possible synergy in the Higgs sector (with and without CP violation), in the determination of the anomalous vector boson couplings and last but not the least, in the search for extra dimensions and radions. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0604/0604230v1.pdf"}
{"id": "hep-ph0702180", "abstract": "  We have studied the dependence of the allowed space of the atmospheric neutrino oscillation parameters on the time of exposure for a magnetized Iron CALorimeter (ICAL) detector at the India-based Neutrino Observatory (INO). We have performed a Monte Carlo simulation for a 50 kTon ICAL detector generating events by the neutrino generator NUANCE and simulating the detector response by GEANT. A chi-square analysis for the ratio of the up-going and down-going neutrinos as a function of L/E is performed and the allowed regions at 90", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0702/0702180v3.pdf"}
{"id": "hep-ph9311242", "abstract": "  Significant progress has recently been achieved in the lattice gauge theory calculations required for extracting the fundamental parameters of the standard model from experiment. Recent lattice determinations of such quantities as the kaon B parameter, the mass of the b quark, and the strong coupling constant have produced results and uncertainties as good or better than the best conventional determinations. Many other calculations crucial to extracting the fundamental parameters of the standard model from experimental data are undergoing very active development. I review the status of such applications of lattice QCD to standard model phenomenology, and discuss the prospects for the near future. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9311/9311242v1.pdf"}
{"id": "hep-ph9401280", "abstract": "  A description of the NN scattering is constructed starting from the π, η, η' pseudoscalar-, the ρ, ϕ, ω vector-, and the ε(600), a_0, f_0(1400) scalar - meson-nucleon coupling constants, which we obtain within a relativistic quark model. Working within the Blankenbecler-Sugar-Logunov-Tavkhelidze quasipotential dynamics we thus describe the NN phase shifts in a relativistically invariant way. In this procedure we use the phenomenological form factor cutoff masses and the effective ε and ω meson-nucleon coupling constants, only. The comparison of our NN phase shifts to the both empirical data and the Bonn OBEP fit shows good agreement – the ratio of the χ^2 for the present results to the χ^2 for Bonn OBEP description is 1.2. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9401/9401280v1.pdf"}
{"id": "hep-ph9409234", "abstract": "  We study CP violation in a multi-Higgs doublet model based on a S_3 × Z_3 horizontal symmetry. We consider two mechanisms for CP violation in this model: a) CP violation due to complex Yukawa couplings; and b) CP violation due to scalar-pseudoscalar mixings. We find that the predictions for ϵ'/ϵ, CP violation in B decays and the electric dipole moments of neutron and electron are different between these two mechanisms. These predictions are also dramatically different from the minimal Standard Model predictions. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9409/9409234v1.pdf"}
{"id": "hep-ph9411402", "abstract": "  Equal time, point to point correlation functions for spatially separated meson currents are calculated with respect to a variational construct for the ground state of QCD. With exact calculations, vector, axial vector and scalar channels show qualitative agreement with the phenomenological predictions, where as pseudoscalar channel does not. However, the pseudoscalar correlator, when approximated by saturating with intermediate one pion states agrees with results obtained from spectral density functions parametrised by pion decay constant and <ψ̅ψ> value obtained from chiral perturbation theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9411/9411402v1.pdf"}
{"id": "hep-ph9507256", "abstract": "  In this paper we present the derivation as well as the numerical results for the electromagnetic form factors of the nucleon within the chiral quark soliton model in the semiclassical quantization scheme. The model is based on semibosonized SU(2) Nambu – Jona-Lasinio lagrangean, where the boson fields are treated as classical ones. Other observables, namely the nucleon mean squared radii, the magnetic moments, and the nucleon–Δ splitting are calculated as well. The calculations have been done taking into account the quark sea polarization effects. The final results, including rotational 1/N_c corrections, are compared with the existing experimental data, and they are found to be in a good agreement for the constituent quark mass of about 420 MeV. The only exception is the neutron electric form factor which is overestimated. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9507/9507256v1.pdf"}
{"id": "hep-ph9510294", "abstract": "  We present results for the B →π and D→π form factors derived from QCD sum rules on the light-cone. Our predictions are compared with experiment and used to extract the quark mixing parameter |V_ub| from a recent CLEO measurement of B π l^+ ν. Furthermore, we discuss the factorization approximation for exclusive nonleptonic matrix elements, and describe a first QCD estimate of the nonfactorizable contribution to the amplitude of B → J/ψ K. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9510/9510294v1.pdf"}
{"id": "hep-ph9511441", "abstract": "  The electromagnetic form factor for the K^0 is calculated in a covariant formulation of the Salpeter equation for qq̅ - bound states, which has been presented recently for the mass spectrum, decay properties and form factors of the light pseudoscalar and vector mesons. The K^0 charge radius dependence on the difference between strange and down constituent quark mass is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9511/9511441v1.pdf"}
{"id": "hep-ph9710406", "abstract": "  We study the production and the evolution of quark-gluon plasma expected to be formed in ultra relativistic heavy-ion collisions, within the color flux-tube model. We introduce the gluonic component in the Boltzmann equation, which we solve in the phase space which is extended to include the SU(3) color degree of freedom. The color degree of freedom is shown to play a decisive role in equilibration, and in fixing the temperature of the plasma. We further find that the soft partons that we study here contribute substantially to the bulk properties. Finally, the model is shown to provide a detailed picture of how the quark-gluon plasma evolves and is driven towards a hydrodynamic flow, which starts occuring around 1 fm. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9710/9710406v2.pdf"}
{"id": "hep-ph9803437", "abstract": "  A model for the production of large rapidity gaps being implemented in the Monte Carlo event generator PHOJET is discussed. In this model, high-mass diffraction dissociation exhibits properties similar to hadron production in non-diffractive hadronic collisions at high energies. Hard diffraction is described using leading-order QCD matrix elements together with a parton distribution function for the pomeron and pomeron-flux factorization. Since this factorization is imposed on Born graph level only, unitarity corrections lead to a non-factorizing flux function. Rapidity gaps between jets are obtained by soft color reconnection. It was previously shown that this model is able to describe data on diffractive hadron production from the CERN-SPS collider and from the HERA lepton-proton collider. In this work we focus on the model predictions for rapidity gap events in p-p collisions at √(s) = 1800 GeV and compare to TEVATRON data. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9803/9803437v1.pdf"}
{"id": "hep-ph9804375", "abstract": "  Within the framework of effective action QED, we derive the light cone condition for homogeneous non-trivial QED vacua in the geometric optics approximation. Our result generalizes the “unified formula” suggested by Latorre, Pascual and Tarrach and allows for the calculation of velocity shifts and refractive indices for soft photons travelling through these vacua. Furthermore, we clarify the connection between the light velocity shift and the scale anomaly. This study motivates the introduction of a so-called effective action charge that characterizes the velocity modifying properties of the vacuum. Several applications are given concerning vacuum modifications caused by, e.g., strong fields, Casimir systems and high temperature. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9804/9804375v1.pdf"}
{"id": "hep-ph9903349", "abstract": "  We show how to construct covariant amplitudes for processes involving higher spins in this paper. First we give the explicit expressions of Rarita-Schwinger wave functions and propagators for bosons with spins, then kinematic singularity free 3-leg effective vertexes are derived and given in a list. Equivalence relations are worked out to get these independent vertexes. Constraints of space reflection symmetry and boson symmetry are considered and shown in a explicit way. Some helicity amplitudes for two-body decays in center of frame are calculated. Finally the covariant helicity amplitudes for the process a_1→π^+π^+π^- are constructed to illustrate how to include background (1PI) amplitudes. Both background amplitudes and resonance amplitudes are needed to give reliable descriptions to high energy reactions. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9903/9903349v1.pdf"}
{"id": "hep-ph9906402", "abstract": "  The hadroproduction of lepton pairs with mass Q and transverse momentum Q_T can be described in perturbative QCD by the same partonic subprocesses as prompt photon production. We demonstrate that, like prompt photon production, lepton pair production is dominated by quark-gluon scattering in the region Q_T>Q/2. This leads to sensitivity to the gluon density in kinematical regimes that are accessible both at collider and fixed target experiments while eliminating the theoretical and experimental uncertainties present in prompt photon production. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9906/9906402v1.pdf"}
{"id": "hep-ph9911205", "abstract": "  We calculate the double spin asymmetry of the diffractive Q Q̅ and vector meson leptoproduction at COMPASS energies. We analyze dependences of the asymmetry on the structure of the Pomeron-proton coupling. It is shown that it is difficult to study the spin structure of the Pomeron coupling with the proton from the A_ll asymmetry. The A_lT asymmetry might be an appropriate object for this investigation. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9911/9911205v1.pdf"}
{"id": "hep-ph9911529", "abstract": "  We report on the next-to-leading order QCD calculation for e+ e- –> 4 jets. We explain some modern techniques which have been used to calculate the one-loop amplitudes efficiently. We further report on the general purpose numerical program “Mercutio”, which can be used to calculate any infrared safe four-jet quantity in electron-positron annihilation at next-to-leading order. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9911/9911529v1.pdf"}
{"id": "hep-th0005082", "abstract": "  One of the main difficulties in studying Quantum Field Theory, in the perturbative regime, is the calculation of D-dimensional Feynman integrals. In general, one introduces the so-called Feynman parameters and associated with them the cumbersome parametric integrals. Solving these integrals beyond the one-loop level can be a difficult task. Negative dimensional integration method () is a technique whereby such problem is dramatically reduced. In this work we present the calculation of two-loop integrals in three diferent cases: scalar ones with three diferent masses, massless with arbitrary tensor rank, with N-insertions of a 2-loop diagram. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0005/0005082v1.pdf"}
{"id": "hep-th0202063", "abstract": "  A long-standing problem of theoretical physics is the exceptionally small value of the cosmological constant Λ∼ 10^-120 measured in natural Planckian units. Here we derive this tiny number from a toroidal string cosmology based on closed strings. In this picture the dark energy arises from the correlation between momentum and winding modes that for short distances has an exponential fall-off with increasing values of the momenta. The freeze-out by the expansion of the background universe for these transplanckian modes may be interpreted as a frozen condensate of the closed-string modes in the three non-compactified spatial dimensions. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0202/0202063v1.pdf"}
{"id": "hep-th0205157", "abstract": "  We present numerical evidence for the existence of spinning generalizations for non-topological Q-ball solitons in the theory of a complex scalar field with a non-renormalizable self-interaction. To the best of our knowledge, this provides the first explicit example of spinning solitons in 3+1 dimensional Minkowski space. In addition, we find an infinite discrete family of radial excitations of non-rotating Q-balls, and construct also spinning Q-balls in 2+1 dimensions. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0205/0205157v3.pdf"}
{"id": "hep-th0208063", "abstract": "  We investigate a method to evaluate quasi-normal modes of D3-brane black holes by wave interpretation of fields on D3-brane based on the Feynman's space-time approach. We perturbatively solve the wave equation which describes propagation of a dilaton wave in a bulk space and its interaction with the D3-brane. The obtained condition for the quasi-normal modes are qualitatively equivalent to that evaluated in the usual scattering of the dilaton in the black 3-brane spacetime in the corresponding supergravity description. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0208/0208063v2.pdf"}
{"id": "hep-th0301167", "abstract": "  Calculations of the two-loop β-function for N=1 supersymmetric electrodynamics are compared for regularizations by higher derivatives and by the dimensional reduction. The renormalized effective action are found to be the same for both regularizations. However, unlike the dimensional reduction, the higher derivative regularization does not lead to anomaly puzzle, because it allows to perform correct calculation of diagrams with insertions of counterterms. In particular, using this method a contribution of diagrams with insertions of counterterms is calculated exactly to all orders. This contribution appears to be 0 if the theory is regularized by the dimensional reduction. We argue, that this result follows from mathematical inconsistency of the dimensional reduction and is responsible for the anomaly puzzle. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0301/0301167v2.pdf"}
{"id": "hep-th0304125", "abstract": "  One-loop corrections to kink masses in a family of (1+1)-dimensional field theoretical models with two real scalar fields are computed. A generalized DHN formula applicable to potentials with and without reflection is obtained. It is shown how half-bound states arising in the spectrum of the second order fluctuation operator for one-component topological kinks and the vacuum play a central rôle in the computation of the kink Casimir energy. The issue of whether or not the kink degeneracy exhibited by this family of models at the classical level survives one-loop quantum fluctuations is addressed. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0304/0304125v3.pdf"}
{"id": "hep-th0306247", "abstract": "  We introduce a finite dimensional matrix model approximation to the algebra of functions on a disc based on noncommutative geometry. The algebra is a subalgebra of the one characterizing the noncommutative plane with a * product and depends on two parameters N and theta. It is composed of functions which decay exponentially outside a disc. In the limit in which the size of the matrices goes to infinity and the noncommutativity parameter goes to zero the disc becomes sharper. We introduce a Laplacian defined on the whole algebra and calculate its eigenvalues. We also calculate the two–points correlation function for a free massless theory (Green's function). In both cases the agreement with the exact result on the disc is very good already for relatively small matrices. This opens up the possibility for the study of field theories on the disc with nonperturbative methods. The model contains edge states, a fact studied in a similar matrix model independently introduced by Balachandran, Gupta and Kurkcuoglu. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0306/0306247v2.pdf"}
{"id": "hep-th0311158", "abstract": "  Vacuum expectation values of the energy-momentum tensor for a conformally coupled scalar field is investigated in de Sitter (dS) spacetime in presence of a curved brane on which the field obeys the Robin boundary condition with coordinate dependent coefficients. To generate the corresponding vacuum densities we use the conformal relation between dS and Rindler spacetimes and the results previously obtained by one of the authors for the Rindler counterpart. The resulting energy-momentum tensor is non-diagonal and induces anisotropic vacuum stresses. The asymptotic behaviour of this tensor is investigated near the dS horizon and the boundary. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0311/0311158v1.pdf"}
{"id": "hep-th0410138", "abstract": "  We study junctions consisting of confining strings in N=1 supersymmetric large N gauge theories by means of the gauge/gravity correspondence. We realize these junctions as D-brane configurations in infrared geometries of the Klebanov-Strassler (KS) and the Maldacena-Nunez (MN) solutions. After discussing kinematics associated with the balance of tensions, we compute the energies of baryon vertices numerically. In the KS background, baryon vertices give negative contributions to the energies. The results for the MN background strongly suggest that the energies of baryon vertices exactly vanish, as in the case of supersymmetric (p,q)-string junctions. We find that brane configurations in the MN background have a property similar to the holomorphy of the M-theory realization of (p,q)-string junctions. With the help of this property, we analytically prove the vanishing of the energies of baryon vertices in the MN background. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0410/0410138v3.pdf"}
{"id": "hep-th0501025", "abstract": "  The properties of future singularities are investigated in the universe dominated by dark energy including the phantom-type fluid. We classify the finite-time singularities into four classes and explicitly present the models which give rise to these singularities by assuming the form of the equation of state of dark energy. We show the existence of a stable fixed point with an equation of state w<-1 and numerically confirm that this is actually a late-time attractor in the phantom-dominated universe. We also construct a phantom dark energy scenario coupled to dark matter that reproduces singular behaviors of the Big Rip type for the energy density and the curvature of the universe. The effect of quantum corrections coming from conformal anomaly can be important when the curvature grows large, which typically moderates the finite-time singularities. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0501/0501025v2.pdf"}
{"id": "hep-th0501036", "abstract": "  In this paper we give a much more efficient proof that the real Euclidean phi 4-model on the four-dimensional Moyal plane is renormalizable to all orders. We prove rigorous bounds on the propagator which complete the previous renormalization proof based on renormalization group equations for non-local matrix models. On the other hand, our bounds permit a powerful multi-scale analysis of the resulting ribbon graphs. Here, the dual graphs play a particular rôle because the angular momentum conservation is conveniently represented in the dual picture. Choosing a spanning tree in the dual graph according to the scale attribution, we prove that the summation over the loop angular momenta can be performed at no cost so that the power-counting is reduced to the balance of the number of propagators versus the number of completely inner vertices in subgraphs of the dual graph. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0501/0501036v1.pdf"}
{"id": "hep-th9608127", "abstract": "  Method for computing scattering amplitudes of open strings with Dirichlet boundary on one end and Neumann boundary condition on the other is described. Vertex operator for these states are constructed using twist fields which have been studied previously in the context of Ashkin-Teller model and strings on orbifolds. Using these vertex operators, we compute the three- and four-point scattering amplitudes for (5,9) strings on 5-branes and 9-branes. In the low energy limit, these amplitudes are found to be in exact agreement with the field theory amplitudes for supersymmetric Yang-Mills coupled to hypermultiplets in 6-dimensions. We also consider the 1-brane 5-brane system and compute the amplitude for a pair of (1,5) strings to collide and to escape the brane as a closed string. (1,5) strings are found to be remarkably selective in their coupling to massless closed strings in NS-NS sector; they only couple to the dilaton. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/9608/9608127v1.pdf"}
{"id": "hep-th9610020", "abstract": "  A new two-step renormalization procedure is proposed. In the first step, the effects of high-energy states are considered in the conventional (Feynman) perturbation theory. In the second step, the coupling to many-body states is eliminated by a similarity transformation. The resultant effective Hamiltonian contains only interactions which do not change particle number. It is subject to numerical diagonalization. We apply the general procedure to a simple example for the purpose of illustration. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/9610/9610020v1.pdf"}
{"id": "hep-th9801036", "abstract": "  Five dimensional supersymmetric gauge theory compactified on a circle defines an effective N=2 supersymmetric theory for massless fields in four dimensions. Based on the relativistic Toda chain Hamiltonian proposed by Nekrasov, we derive the Picard-Fuchs equation on the moduli space of the Coulomb branch of SU(2) gauge theory. Our Picard-Fuchs equation agrees with those from other approaches; the spectral curve of XXZ spin chain and supersymmetric cycle in compactified M theory. By making use of a relation to the Picard-Fuchs equation of SU(2) Seiberg-Witten theory, we obtain the prepotential and the effective coupling constant that incorporate both a perturbative effect of Kaluza-Klein modes and a non-perturbative one of four dimensional instantons. In the weak coupling regime we check that the prepotential exhibits a consistent behavior in large and small radius limits of the circle. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/9801/9801036v2.pdf"}
{"id": "hep-th9807085", "abstract": "  We give a reinterpretation of the matrix theory discussed by Moore, Nekrasov and Shatashivili (MNS) in terms of the second quantized operators which describes the homology class of the Hilbert scheme of points on surfaces. It naturally relate the contribution from each pole to the inner product of orthogonal basis of free boson Fock space. These basis can be related to the eigenfunctions of Calogero-Sutherland (CS) equation and the deformation parameter of MNS is identified with coupling of CS system. We discuss the structure of Virasoro symmetry in this model. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/9807/9807085v1.pdf"}
{"id": "hep-th9912186", "abstract": "  We construct a class of solutions to the Einstein's equations for dimensions greater than or equal to six. These solutions are characterized by a non-trivial warp factor and possess a non-compact extra dimension. We study in detail a simple model in six dimensions containing two four branes. One of each brane's four spatial directions is compactified. The hierarchy problem is resolved by the enormous difference between the warp factors at the positions of the two branes, with the standard model fields living on the brane with small warp factor. Both branes can have positive tensions. Their positions, and the size of the compact dimension are determined in terms of the fundamental parameters of the theory by a combination of two independent and comparable effects—an anisotropic contribution to the stress tensor of each brane from quantum fields living on it and a contribution to the stress tensor from a bulk scalar field. One overall fine tuning of the parameters of the theory is required —that for the cosmological constant. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/9912/9912186v2.pdf"}
{"id": "math-ph0106003", "abstract": "  In this paper we propose and advocate the use of the so called Lévy flights as a driving mechanism for a class of stochastic optimization computations. This proposal, for some reasons overlooked until now, is - in author's opinion - very appropriate to satisfy the need for algorithm, which is capable of generating trial steps of very different length in the search space. The required balance between short and long steps can be easily and fully controlled. A simple example of approximated Lévy distribution, implemented in FORTRAN 77, is given. We also discuss the physical grounds of presented methods. ", "pdf_url": "gs://arxiv-dataset/arxiv/math-ph/pdf/0106/0106003v1.pdf"}
{"id": "math-ph0406044", "abstract": "  We consider network models of quantum localisation in which a particle with a two-component wave function propagates through the nodes and along the edges of an arbitrary directed graph, subject to a random SU(2) rotation on each edge it traverses. The propagation through each node is specified by an arbitrary but fixed S-matrix. Such networks model localisation problems in class C of the classification of Altland and Zirnbauer, and, on suitable graphs, they model the spin quantum Hall transition. We extend the analyses of Gruzberg, Ludwig and Read and of Beamond, Cardy and Chalker to show that, on an arbitrary graph, the mean density of states and the mean conductance may be calculated in terms of observables of a classical history-dependent random walk on the same graph. The transition weights for this process are explicitly related to the elements of the S-matrices. They are correctly normalised but, on graphs with nodes of degree greater than 4, not necessarily non-negative (and therefore interpretable as probabilities) unless a sufficient number of them happen to vanish. Our methods use a supersymmetric path integral formulation of the problem which is completely finite and rigorous. ", "pdf_url": "gs://arxiv-dataset/arxiv/math-ph/pdf/0406/0406044v1.pdf"}
{"id": "math0003204", "abstract": "  We consider subtorus actions on complex toric varieties. A natural candidate for a categorical quotient of such an action is the so-called toric quotient, a universal object constructed in the toric category. We prove that if the toric quotient is weakly proper and if in addition the quotient variety is of expected dimension then the toric quotient is in fact a categorical quotient in the category of algebraic varieties. For example, weak properness always holds for the toric quotient of a subtorus action on a toric variety whose fan has a convex support. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0003/0003204v3.pdf"}
{"id": "math0103015", "abstract": "  We study groups generated by three half-turns in the Lobachevsky 3-space and their quotient orbifolds. These generalized triangle groups are closely related to the arbitrary 2-generator Kleinian groups. Our main result is a classification of the singular sets of the generalized triangle orbifolds. We also present a method to obtain the parameters defining a generalized triangle group from the structure of the singular set of its quotient orbifold and illustrate it by examples. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0103/0103015v4.pdf"}
{"id": "math0211351", "abstract": "  We study the dynamics of a class of interval translation map on three intervals. We show that in this class the typical ITM is of finite type (reduce to an interval exchange transformation) and that the complement contains a Cantor set. We relate our maps to substitution subshifts. Results on Hausdorff dimension of the attractor and on unique ergodicity are obtained. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0211/0211351v2.pdf"}
{"id": "math0503369", "abstract": "  This paper provides an introduction to equivariant cohomology and homology using the approach of Goresky, Kottwitz, and MacPherson. When a group G acts suitably on a variety X, the equivariant cohomology of X can be computed using the combinatorial data of a skeleton of G-orbits on X. We give both a geometric definition and the traditional definition of equivariant cohomology. We include a discussion of the moment map and an algorithm for finding a set of generators for the equivariant cohomology of X. Many examples and explicit calculations are provided. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0503/0503369v1.pdf"}
{"id": "math0504477", "abstract": "  The existing literature on stochastic simulation of chemical reaction networks has a tendency to move as quickly as possible to the abstract formulation of the stochastic dynamics in terms of probabilities based on the concept of the Chemical Master Equation (CME), largely ignoring sample path representation.   In this publication we discuss both theoretical basis and numerical approach for the problems in this area using sample path methods as a crucial part of the process. Relying as it does on a representation of the underlying stochastic processes as a weak solution of a system of stochastic differential equations driven by Poisson random measures this approach brings to bear a heretofore ignored but quite effective problem solving methodology. We first present a simple and intuitive way of partitioning species and reactions of the interaction network into different groups. We then discuss how original stochastic dynamics with state dependent intensities of transitions can be reformulated in terms of jump-diffusion stochastic differential equations driven by both Wiener noise sources and Poisson random measures. Finally, we show that this approach facilitates the construction of hybrid simulation techniques, an important step in the creation of efficient techniques for modeling multi-scale stochastic dynamics of the reaction networks.   Numerical methods related to sampling events from Poisson random measures are demonstratedon simple intuitive examples. Error control analysis of the finite differences scheme is also presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0504/0504477v1.pdf"}
{"id": "math0510382", "abstract": "  We define a family of formal Khovanov brackets of a colored link depending on two parameters. The isomorphism classes of these brackets are invariants of framed colored links. The Bar-Natan functors applied to these brackets produce Khovanov and Lee homology theories categorifying the colored Jones polynomial. Further, we study conditions under which framed colored link cobordisms induce chain transformations between our formal brackets. We conjecture that, for special choice of parameters, Khovanov and Lee homology theories of colored links are functorial (up to sign). Finally, we extend the Rasmussen invariant to links and give examples, where this invariant is a stronger obstruction to sliceness than the multivariable Levine-Tristram signature. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0510/0510382v2.pdf"}
{"id": "math0610124", "abstract": "  An open problem in numerical analysis is to explain why molecular dynamics works. The difficulty is that numerical trajectories are only accurate for very short times, whereas the simulations are performed over long time intervals. It is believed that statistical information from these simulations is accurate, but no one has offered a rigourous proof of this. In order to give mathematicians a clear goal in understanding this problem, we state a precise mathematical conjecture about molecular dynamics simulation of a particular system. We believe that if the conjecture is proved, we will then understand why molecular dynamics works. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0610/0610124v2.pdf"}
{"id": "math0703201", "abstract": "  In the Biham-Middleton-Levine traffic model cars are placed with some density p on a two dimensional torus, and move according to a (simple) set of predefined rules. Computer simulations show this system exhibits many interesting phenomena: for low densities the system self organizes such that cars flow freely while for densities higher than some critical density the system gets stuck in an endless traffic jam. However, apart from the simulation results very few properties of the system were proven rigorously to date. We introduce a simplified version of this model in which cars are placed in a single row and column (a junction) and show that similar phenomena of self-organization of the system and phase transition still occur. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0703/0703201v2.pdf"}
{"id": "mtrl-th9607006", "abstract": "  The influence of molecular vibrations on dissociative adsorption is studied by six-dimensional quantum dynamical calculations. For the system H_2 at Pd(100), which possesses non-activated pathways, it is shown that large vibrational effects exist and that they are not due to a strongly curved reaction path and a late dissociation-hindering minimum barrier, as was previously assumed. Instead, they are caused by the lowering of the H-H vibrational frequency during the dissociation and the multi-dimensionality of the potential energy surface. Still there are quantitative discrepancies between theory and experiment identified. ", "pdf_url": "gs://arxiv-dataset/arxiv/mtrl-th/pdf/9607/9607006v1.pdf"}
{"id": "nlin0009005", "abstract": "  We study the effects produced by competition of two physical mechanisms of energy localization in inhomogeneous nonlinear systems. As an example, we analyze spatially localized modes supported by a nonlinear impurity in the generalized nonlinear Schrödinger equation and describe three types of nonlinear impurity modes — one- and two-hump symmetric localized modes and asymmetric localized modes — for both focusing and defocusing nonlinearity and two different (attractive or repulsive) types of impurity. We obtain an analytical stability criterion for the nonlinear localized modes and consider the case of a power-law nonlinearity in detail. We discuss several scenarios of the instability-induced dynamics of the nonlinear impurity modes, including the mode decay or switching to a new stable state, and collapse at the impurity site. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0009/0009005v1.pdf"}
{"id": "nlin0012022", "abstract": "  A simple quasiperiodically forced one-dimensional cubic map is shown to exhibit very many types of routes to chaos via strange nonchaotic attractors (SNAs) with reference to a two-parameter (A-f) space. The routes include transitions to chaos via SNAs from both one frequency torus and period doubled torus. In the former case, we identify the fractalization and type I intermittency routes. In the latter case, we point out that atleast four distinct routes through which the truncation of torus doubling bifurcation and the birth of SNAs take place in this model. In particular, the formation of SNAs through Heagy-Hammel, fractalization and type–III intermittent mechanisms are described. In addition, it has been found that in this system there are some regions in the parameter space where a novel dynamics involving a sudden expansion of the attractor which tames the growth of period-doubling bifurcation takes place, giving birth to SNA. The SNAs created through different mechanisms are characterized by the behaviour of the Lyapunov exponents and their variance, by the estimation of phase sensitivity exponent as well as through the distribution of finite-time Lyapunov exponents. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0012/0012022v1.pdf"}
{"id": "nlin0204069", "abstract": "  As a streak of dye is advected by a chaotic flow, it stretches and folds and becomes indistinguishable from a one-dimensional idealized material line. The variation along a material line of the total stretching experienced by fluid elements is examined, and it is found that it can be decomposed into an overall time-dependent factor, constant along the line, and a smooth time-independent deviation. The stretching is related by a power law to the curvature of the line near sharp bends. This is confirmed numerically and motivated by a simple model. A conservation law for Lyapunov exponents explains deviations from a power-law. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0204/0204069v3.pdf"}
{"id": "nlin0209015", "abstract": "  We describe a method for analyzing the phase space structures of Hamiltonian systems. This method is based on a time-frequency decomposition of a trajectory using wavelets. The ridges of the time-frequency landscape of a trajectory, also called instantaneous frequencies, enable us to analyze the phase space structures. In particular, this method detects resonance trappings and transitions and allows a characterization of the notion of weak and strong chaos. We illustrate the method with the trajectories of the standard map and the hydrogen atom in crossed magnetic and elliptically polarized microwave fields. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0209/0209015v1.pdf"}
{"id": "nlin0210030", "abstract": "  In quantum/wave systems with chaotic classical analogs, wavefunctions evolve in highly complex, yet deterministic ways. A slight perturbation of the system, though, will cause the evolution to diverge from its original behavior increasingly with time. This divergence can be measured by the fidelity, which is defined as the squared overlap of the two time evolved states. For chaotic systems, two main decay regimes of either Gaussian or exponential behavior have been identified depending on the strength of the perturbation. For perturbation strengths intermediate between the two regimes, the fidelity displays both forms of decay. By applying a complementary combination of random matrix and semiclassical theory, a uniform approximation can be derived that covers the full range of perturbation strengths. The time dependence is entirely fixed by the density of states and the so-called transition parameter, which can be related to the phase space volume of the system and the classical action diffusion constant, respectively. The accuracy of the approximations are illustrated with the standard map. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0210/0210030v2.pdf"}
{"id": "nlin0211047", "abstract": "  The Lyapunov spectrum describes the exponential growth, or decay, of infinitesimal phase-space perturbations. The perturbation associated with the maximum Lyapunov exponent is strongly localized in space, and only a small fraction of all particles contributes to the perturbation growth at any instant of time. This fraction converges to zero in the thermodynamic large-particle-number limit. For hard-disk and hard-sphere systems the perturbations belonging to the small positive and large negative exponents are coherently spread out and form orthogonal periodic structures in space, the “Lyapunov modes”. There are two types of mode polarizations, transverse and longitudinal. The transverse modes do not propagate, but the longitudinal modes do with a speed about one third of the sound speed. We characterize the symmetry and the degeneracy of the modes. In the thermodynamic limit the Lyapunov spectrum has a diverging slope near the intersection with the abscissa. No positive lower bound exists for the positive exponents. The mode amplitude scales with the inverse square root of the particle number as expected from the normalization of the perturbation vectors. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0211/0211047v1.pdf"}
{"id": "nlin0401013", "abstract": "  We study the properties of linear and nonlinear waveguides induced by optical vortex solitons in both self-defocusing and self-focusing nonlinear media, for the case of a saturable nonlinear response. We demonstrate that the vortex-induced waveguides can guide both fundamental and first-order guided modes which together with the vortex may form, for larger amplitudes of the guide modes, different types of composite vortex-mode vector solitons. In the case of the self-focusing saturable medium, we demonstrate that a large-amplitude guided mode can stabilize the ring-like vortex structure which usually decays due to azimuthal modulational instability. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0401/0401013v1.pdf"}
{"id": "nlin0409060", "abstract": "  Using the numerical solution of the nonlinear Schroedinger equation and a variational method it is shown that (3+1)-dimensional spatiotemporal optical solitons can be stabilized by a rapidly oscillating dispersion coefficient in a Kerr medium with cubic nonlinearity. This has immediate consequence in generating dispersion-managed robust optical soliton in communication as well as possible stabilized Bose-Einstein condensates in periodic optical-lattice potential via an effective-mass formulation. We also critically compare the present stabilization with that obtained by a rapid sinusoidal oscillation of the Kerr nonlinearity parameter. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0409/0409060v2.pdf"}
{"id": "nlin0504063", "abstract": "  Analogy between an approximate version of Feigenbaum renormalization group analysis in complex domain and the phase transition theory of Yang-Lee (based on consideration of formally complexified thermodynamic values) is discussed. It is shown that the Julia sets of the renormalization transformation correspond to the approximation of Mandelbrot set of the original map. New aspects of analogy between the theory of dynamical systems and the phase transition theory are uncovered. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0504/0504063v1.pdf"}
{"id": "nlin0512057", "abstract": "  In the limit of small values of the aspect ratio parameter (or wave steepness) which measures the amplitude of a surface wave in units of its wave-length, a model equation is derived from the Euler system in infinite depth (deep water) without potential flow assumption. The resulting equation is shown to sustain periodic waves which on the one side tend to the proper linear limit at small amplitudes, on the other side possess a threshold amplitude where wave crest peaking is achieved. An explicit expression of the crest angle at wave breaking is found in terms of the wave velocity. By numerical simulations, stable soliton-like solutions (experiencing elastic interactions) propagate in a given velocities range on the edge of which they tend to the peakon solution. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0512/0512057v1.pdf"}
{"id": "nlin0512070", "abstract": "  We study stability of interacting nonlinear systems with time-delayed communications, using contraction theory and a simplified wave variable design inspired by robotic teleoperation. We show that contraction is preserved through specific time-delayed feedback communications, and that this property is independent of the values of the delays. The approach is then applied to group cooperation with linear protocols, where it shown that synchronization can be made robust to arbitrary time delays. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0512/0512070v1.pdf"}
{"id": "nlin0606057", "abstract": "  The classical Hamiltonian system of time-dependent harmonic oscillator driven by the arbitrary external time-dependent force is considered. Exact analytical solution of the corresponding equations of motion is constructed in the framework of the technique (Robnik M, Romanovski V G, J. Phys. A: Math. Gen. 33 (2000) 5093) based on WKB approach. Energy evolution for the ensemble of uniformly distributed w.r.t. the canonical angle initial conditions on the initial invariant torus is studied. Exact expressions for the energy moments of arbitrary order taken at arbitrary time moment are analytically derived. Corresponding characteristic function is analytically constructed in the form of infinite series and numerically evaluated for certain values of the system parameters. Energy distribution function is numerically obtained in some particular cases. In the limit of small initial ensemble's energy the relevant formula for the energy distribution function is analytically derived. ", "pdf_url": "gs://arxiv-dataset/arxiv/nlin/pdf/0606/0606057v2.pdf"}
{"id": "nucl-ex0310033", "abstract": "  We have measured production cross sections and longitudinal momentum distributions of fragments from neutron-deficient 36Ar at 1.05 A.GeV. The production cross-sections show excellent agreement with the predictions of the semiempirical formula EPAX. We have compared these results, involving extremly neutron deficient nuclei, with model calculations to extract informa tion about the response of these models close to the driplines. The longitudinal momentum distributions have also been extracted and are compared with the Goldhaber and Morrissey systematics. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/0310/0310033v1.pdf"}
{"id": "nucl-ex0504030", "abstract": "  The use of radioactive beams opens a new frontier for fusion studies. The coupling to the continuum can be explored with very loosely bound nuclei. Experiments were performed with beams of nuclei at or near the proton and neutron drip-lines to measure fusion and associated reactions in the vicinity of the Coulomb barrier. In addition, the fusion yield is predicted to be enhanced in reactions involving very neutron-rich unstable nuclei. Experimental measurements were carried out to investigate if it is feasible to use such beams to produce new heavy elements. The current status of these experimental activities is given in this review. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/0504/0504030v1.pdf"}
{"id": "nucl-ex0509039", "abstract": "  We present the first measurement of multiplicity and pseudorapidity distributions of photons in the pseudorapidity region 2.3 < eta < 3.7 for different centralities in Au + Au collisions at sqrts_NN = 62.4 GeV. The pseudorapidity distribution of photons, dominated by neutral pion decays, has been compared to those of identified charged pions, photons, and inclusive charged particles from heavy ion and nucleon-nucleon collisions at various energies. Scaling of photon yield with number of participating nucleons and limiting fragmentation scenario for inclusive photon production has been studied. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/0509/0509039v1.pdf"}
{"id": "nucl-ex0611010", "abstract": "  Experiments on strangeness production in nucleus-nucleus collisions at SIS energies address fundamental aspects of modern nuclear physics: the determination of the nuclear equation-of-state at high baryon densities and the properties of hadrons in dense nuclear matter. Experimental data and theoretical results will be reviewed. Future experiments at the FAIR accelerator aim at the exploration of the QCD phase diagram at highest baryon densities. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/0611/0611010v1.pdf"}
{"id": "nucl-ex9811006", "abstract": "  We report on the latest results in the search for positively charged strangelets from E864's 96/97 run at the AGS with sensitivity of about 8× 10^-9 per central collision. This contribution also contains new results of a search for highly charged strangelets with Z=+3. Production of light nuclei, such as ^6He and ^6Li, is presented as well. Measurements of yields of these rarely produced isotopes near midrapidity will help constrain the production levels of strangelets via coalescence. E864 also measures antiproton production which includes decays from antihyperons. Comparisons with antiproton yields measured by E878 as a function of centrality indicate a large antihyperon-to-antiproton ratio in central collisions. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/9811/9811006v1.pdf"}
{"id": "nucl-th0005050", "abstract": "  Point-form relativistic quantum mechanics is applied to elastic electron-deuteron scattering. The deuteron is modeled using relativistic interactions that are scattering-equivalent to the nonrelativistic Argonne v_18 and Reid '93 interactions. A point-form spectator approximation (PFSA) is introduced to define a conserved covariant current in terms of single-nucleon form factors. The PFSA is shown to provide an accurate description of data up to momentum transfers of 0.5 GeV^2, but falls below the data at higher momentum transfers. Results are sensitive to the nucleon form factor parameterization chosen, particularly to the neutron electric form factor. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0005/0005050v2.pdf"}
{"id": "nucl-th0203050", "abstract": "  The phase diagram, (T,ρ), of a finite, constrained, and classical system is built from the analysis of cluster distributions in phase and configurational space. The obtained phase diagram can be split in three regions. One, low density limit, in which first order phase transition features can be observed. Another one, corresponding to the high density regime, in which fragments in phase space display critical behavior of 3D-Ising universality class type. And an intermediate density region, in which power-laws are displayed but can not be associated to the abovementioned universality class. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0203/0203050v1.pdf"}
{"id": "nucl-th0302058", "abstract": "  Self-consistent mean field calculations with the SLy4 interaction and a density-dependent pairing force are presented for nuclei in the Nobelium mass region. Predicted quasi-particle spectra are compared with experiment for the heaviest known odd N and odd Z nuclei. Spectra and rotational bands are presented for nuclei around No252,4 for which experiments are either planned or already running. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0302/0302058v1.pdf"}
{"id": "nucl-th0303035", "abstract": "  The recently developed auxiliary field diffusion Monte Carlo method is applied to compute the equation of state and the compressibility of neutron matter. By combining diffusion Monte Carlo for the spatial degrees of freedom and auxiliary field Monte Carlo to separate the spin-isospin operators, quantum Monte Carlo can be used to simulate the ground state of many nucleon systems (A 100). We use a path constraint to control the fermion sign problem. We have made simulations for realistic interactions, which include tensor and spin–orbit two–body potentials as well as three-nucleon forces. The Argonne v_8' and v_6' two nucleon potentials plus the Urbana or Illinois three-nucleon potentials have been used in our calculations. We compare with fermion hypernetted chain results. We report results of a Periodic Box–FHNC calculation, which is also used to estimate the finite size corrections to our quantum Monte Carlo simulations. Our AFDMC results for v_6 models of pure neutron matter are in reasonably good agreement with equivalent Correlated Basis Function (CBF) calculations, providing energies per particle which are slightly lower than the CBF ones. However, the inclusion of the spin–orbit force leads to quite different results particularly at relatively high densities. The resulting equation of state from AFDMC calculations is harder than the one from previous Fermi hypernetted chain studies commonly used to determine the neutron star structure. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0303/0303035v1.pdf"}
{"id": "nucl-th0401001", "abstract": "  A formalism for hadron production at high in heavy-ion collisions has been developed such that all partons hadronize by recombination. The fragmentation of a hard parton is accounted for by the recombination of shower partons that it creates. Such shower partons can also recombine with the thermal partons to form particles that dominate over all other possible modes of hadronization in the 3<p_T<8 GeV range. The results for the high spectra of pion, kaon, and proton agree well with experiments. Energy loss of partons in the dense medium is taken into account on the average by an effective parameter by fitting data, and is found to be universal independent of the type of particles produced, as it should. Due to the recombination of thermal and shower partons, the structure of jets produced in nuclear collisions is different from that in pp collisions. The consequence on same-side correlations is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0401/0401001v3.pdf"}
{"id": "nucl-th0407092", "abstract": "  We address the problem of collective motion across a barrier like encountered in fission. A formula for the quantal decay rate is derived which bases on a recently developed variational approach for functional integrals. This formula can be applied to low temperatures that have not been accessible within the former PSPA type approach. To account for damping of collective motion one particle Green functions are dressed with appropriate self-energies. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0407/0407092v2.pdf"}
{"id": "nucl-th0502055", "abstract": "  Using the density-dependent Hartree-Fock approximation and Skyrme forces together with the scaling method and constrained Hartree-Fock calculations, we obtain the average energies of the isoscalar giant monopole resonance. The calculations are done along several isotopic chains from the proton to the neutron drip lines. It is found that while approaching the neutron drip line, the scaled and the constrained energies decrease and the resonance width increases. Similar but smaller effects arise near the proton drip line, although only for the lighter isotopic chains. A qualitatively good agreement is found between our sum rule description and the presently existing random phase approximation results. The ability of the semiclassical approximations of the Thomas-Fermi type, which properly describe the average energy of the isoscalar giant monopole resonance for stable nuclei, to predict average properties for nuclei near the drip lines is also analyzed. We show that when hbar corrections are included, the semiclassical estimates reproduce, on average, the quantal excitation energies of the giant monopole resonance for nuclei with extreme isospin values. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0502/0502055v2.pdf"}
{"id": "nucl-th0502063", "abstract": "  We solve the Hartree-Fock-Bogoliubov (HFB) equations for deformed, axially symmetric even-even nuclei in coordinate space on a 2-D lattice utilizing the Basis-Spline expansion method. Results are presented for the neutron-rich zirconium isotopes up to the two-neutron dripline. In particular, we calculate binding energies, two-neutron separation energies, normal densities and pairing densities, mean square radii, quadrupole moments, and pairing gaps. Very large prolate quadrupole deformations (beta2=0.42,0.43,0.47) are found for the (102,104,112)Zr isotopes, in agreement with recent experimental data. We compare 2-D Basis-Spline lattice results with the results from a 2-D HFB code which uses a transformed harmonic oscillator basis. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0502/0502063v1.pdf"}
{"id": "nucl-th0504016", "abstract": "  We investigate the evolution of quantal spectra and the corresponding wave functions along the [O(6)-U(5)]⊃O(5) transition of the interacting boson model. The model is integrable in this regime and its ground state passes through a second-order structural phase transition. We show that the whole spectrum as a function of the Hamiltonian control parameter, as well as structures of all excited states, exhibit rather organized and correlated behaviors, that provide deeper insight into the nature of this transitional path. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0504/0504016v1.pdf"}
{"id": "nucl-th0506062", "abstract": "  At this point it is still unclear whether pentaquarks exist. While they have be seen in some experiments there are many experiments in which they are not found. On the assumption that pentaquarks exist, several authors have studied the properties of pentaquarks. One description considered is that of pentaquarks which consist of a diquark coupled to a triquark. There is a quite extensive literature concerning the properties of diquarks and their importance in the description of the nucleon has been considered by several authors. On the other hand, there is little work reported concerning the description of triquarks. In the present work we study a model for the triquark in which it is composed of a component which contains a quark coupled to a scalar diquark and another two components in which there is a quark coupled to a kaon. We solve for the wave function of the triquark and obtain a mass for the triquark of 0.81 GeV which is quite close to the value of 0.80 GeV obtained in a QCD sum rule study of triquark properties. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0506/0506062v1.pdf"}
{"id": "nucl-th0508058", "abstract": "  Paring correlations in weakly bound nuclei on the edge of neutron drip line is studied by using a three-body model. A density-dependent contact interaction is employed to calculate the ground state of halo nuclei ^6He and ^11Li, as well as a skin nucleus ^24O. Dipole excitations in these nuclei are also studied within the same model. We point out that the di-neutron type correlation plays a dominant role in the halo nuclei ^6He and ^11Li having the coupled spin of the two neutrons S=0, while the correlation similar to the BCS type is important in ^24O. Contributions of the spin S=1 and S=0 configurations are separately discussed in the low energy dipole excitations. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0508/0508058v1.pdf"}
{"id": "nucl-th0512080", "abstract": "  We study thermodynamic characteristica of ultra-relativistic Au+Au collisions at RHIC energy sqrt(s) = 200 GeV within the framework of a microscopic transport model, namely the quark-gluon string model (QGSM). The temporal evolution of the local energy density, transverse and longitudinal pressure and equilibration times are considered. In contrast to complete equilibration which is even in central reactions hardly achieved, pre-equilibrium stages with energy densities well above the critical energy density predicted by lattice QCD are established at short time scales. Corresponding energy density profiles at proper time tau = 1 fm/c compare well with hydrodynamical assumptions for initial energy density distributions. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0512/0512080v1.pdf"}
{"id": "nucl-th0601040", "abstract": "  The program of systematic large-scale self-consistent nuclear mass calculations that is based on the nuclear density functional theory represents a rich scientific agenda that is closely aligned with the main research directions in modern nuclear structure and astrophysics, especially the radioactive nuclear beam physics. The quest for the microscopic understanding of the phenomenon of nuclear binding represents, in fact, a number of fundamental and crucial questions of the quantum many-body problem, including the proper treatment of correlations and dynamics in the presence of symmetry breaking. Recent advances and open problems in the field of nuclear mass calculations are presented and discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0601/0601040v1.pdf"}
{"id": "nucl-th0603034", "abstract": "  No-core shell model (NCSM) calculations using ab initio effective interactions are very successful in reproducing experimental nuclear spectra. The main theoretical approach is the use of effective operators, which include correlations left out by the truncation of the model space to a numerically tractable size. We review recent applications of the effective operator approach, within a NCSM framework, to the renormalization of the nucleon-nucleon interaction, as well as scalar and tensor operators. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0603/0603034v1.pdf"}
{"id": "nucl-th0606007", "abstract": "  Collective transverse flow in heavy-ion collisions at incident energies E_lab = (1 -160)A GeV is analyzed within the model of 3-fluid dynamics (3FD). Simulations are performed with purely hadronic equation of state (EoS). At the AGS energies the flow turns out to be sensitive to the stopping power of nuclear matter rather than only to the stiffness of the EoS. When the stopping power is fixed to reproduce other observables, the flow data favor more and more soft EoS with the incident energy rise, which can be associated with “a transition from hadronic to string matter” reported in the Hadron-String-Dynamics (HSD) model. Problems, which are met in simultaneous reproduction of directed and elliptic flows within the 3FD, suggest that the transverse flow is very sensitive to the character of the transverse-momentum nonequilibrium at the initial stage of collision. Arguments in favor of \"early-stage\" nature of the flow observable are put forward. This suggests that the flow (especially the directed one) is determined by early-stage evolution of the collision rather than freeze-out stage. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0606/0606007v2.pdf"}
{"id": "nucl-th0701063", "abstract": "  With the QGP opacity computed perturbatively and with the global entropy constraints imposed by the observed dN_ch/dy≈1000, radiative energy loss alone cannot account for the observed suppression of single non-photonic electrons. We show that collisional energy loss, which previously has been neglected, is comparable to radiative loss for both light and heavy jets and may in fact be the dominant mechanism for bottom quarks. Predictions taking into account both radiative and collisional losses significantly reduce the discrepancy with data. In addition to elastic energy loss, it is critical to include jet path length fluctuations to account for the observed pion suppression. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0701/0701063v1.pdf"}
{"id": "nucl-th9312003", "abstract": "  We investigate the role of relativistic and nonrelativistic optical potentials used in the analysis of (e,e'p) data. We find that the relativistic calculations produce smaller (e,e'p) cross sections even in the case in which both relativistic and nonrelativistic optical potentials fit equally well the elastic proton–nucleus scattering data. Compared to the nonrelativistic impulse approximation, this effect is due to a depletion in the nuclear interior of the relativistic nucleon current, which should be taken into account in the nonrelativistic treatment by a proper redefinition of the effective current operator. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/9312/9312003v2.pdf"}
{"id": "nucl-th9803027", "abstract": "  A systematic study of the influence of exchange terms in the longitudinal and transverse nuclear response to quasi-elastic (e,e') reactions is presented. The study is performed within the framework of the extended random phase approximation (ERPA), which in conjuction with a projection method permits a separation of various contributions tied to different physical processes. The calculations are performed in nuclear matter up to second order in the residual interaction for which we take a (pi+rho)-model with the addition of the Landau-Migdal g'-parameter. Exchange terms are found to be important only for the RPA-type contributions around the quasielastic peak. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/9803/9803027v1.pdf"}
{"id": "nucl-th9906066", "abstract": "  We compute the recoil polarization of the lambda-hyperon and the photon asymmetry for the quasifree photoproduction of kaons in a relativistic impulse-approximation approach. Our motivation for studying polarization observables is threefold. First, polarization observables are more effective discriminators of subtle dynamics than the unpolarized cross section. Second, earlier nonrelativistic calculations suggest an almost complete insensitivity of polarization observables to distortions effects. Finally, this insensitivity entails an enormous simplification in the theoretical treatment. Indeed, by introducing the notion of a “bound-nucleon propagator” we exploit Feynman's trace techniques to develop closed-form, analytic expressions for all photoproduction observables. Moreover, our results indicate that polarization observables are also insensitive to relativistic effects and to the nuclear target. Yet, they are sensitive to the model parameters, making them ideal tools for the study of modifications to the elementary amplitude — such as in the production, propagation, and decay of nucleon resonances — in the nuclear medium. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/9906/9906066v1.pdf"}
{"id": "nucl-th9906084", "abstract": "  For the calculation of polarization transfer observables for quasielastic scattering of protons on nuclei, a formalism in the context of the Relativistic Plane Wave Impulse Approximation is developed, in which the interaction matrix is expanded in terms of a complete set of 44 independent invariant amplitudes. A boson-exchange model is used to predict the 39 amplitudes which were omitted in the formerly used five-term parameterization(the SPVAT form) of the nucleon-nucleon scattering matrix. Use of the complete set of amplitudes eliminates the arbitrariness of the five-term representation. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/9906/9906084v1.pdf"}
{"id": "nucl-th9909026", "abstract": "  Effective density dependent pairing forces of zero range are adjusted on gap values in T=0,1 channels calculated with the Paris force in symmetric nuclear matter. General discussions on the pairing force are presented. In conjunction with the effective k-mass the nuclear pairing force seems to need very little renormalization in the T=1 channel. The situation in the T=0 channel is also discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/9909/9909026v1.pdf"}
{"id": "nucl-th9910038", "abstract": "  We investigate nuclear matter on a cubic lattice. An exact thermal formalism is applied to nucleons with a Hamiltonian that accommodates on-site and next-neighbor parts of the central, spin- and isospin-exchange interactions. We describe the nuclear matter Monte Carlo methods which contain elements from shell model Monte Carlo methods and from numerical simulations of the Hubbard model. We show that energy and basic saturation properties of nuclear matter can be reproduced. Evidence of a first-order phase transition from an uncorrelated Fermi gas to a clustered system is observed by computing mechanical and thermodynamical quantities such as compressibility, heat capacity, entropy and grand potential. We compare symmetry energy and first sound velocities with literature and find reasonable agreement. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/9910/9910038v1.pdf"}
{"id": "physics0005080", "abstract": "  Influence of pulsed electric field (PEF) simultaneous to pressure treatment on moisture expression from fine-cut cellular raw material has been investigated. Dependencies of specific conductivity σ, liquid yield Y, instantaneous flow rate v and qualitative juice characteristics at different modes of PEF treatment are discussed. Three main consolidation phases were observed in a case of mechanical expression. A unified approach is proposed for liquid yield data analysis allowing to reduce the data scattering caused by differences in the quality of samples. Simultaneous application of pressure and PEF treatment allows to reveal a passive form of electrical damage. Pressure provokes the damage of defected cells, enhances diffusion migration of moisture in porous cellular material and depresses the cell resealing processes. PEF application at a moment when a sample specific electrical conductivity reaches minimum and pressure achieves its constant value seemed to be the most optimal. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0005/0005080v1.pdf"}
{"id": "physics0012024", "abstract": "  Reciprocal space methods for solving Poisson's equation for finite charge distributions are investigated. Improvements to previous proposals are presented, and their performance is compared in the context of a real-space density functional theory code. Two basic methodologies are followed: calculation of correction terms, and imposition of a cut-off to the Coulomb potential. We conclude that these methods can be safely applied to finite or aperiodic systems with a reasonable control of speed and accuracy. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0012/0012024v1.pdf"}
{"id": "physics0110081", "abstract": "  We consider the viscous motion of a thin, axisymmetric column of fluid with a free surface. A one-dimensional equation of motion for the velocity and the radius is derived from the Navier-Stokes equation. We compare with recent experiments on the breakup of a liquid jet and on the bifurcation of a drop suspended from an orifice. The equations form singularities as the fluid neck is pinching off. The nature of the singularities is investigated in detail. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0110/0110081v1.pdf"}
{"id": "physics0209036", "abstract": "  The propagation of light-pulse with negative group-velocity in a nonlinear medium is studied theoretically. We show that the necessary conditions for these effects to be observable are realized in a three-level Λ-system interacting with a linearly polarized laser beam in the presence of a static magnetic field. In low power regime, when all other nonlinear processes are negligible, the light-induced Zeeman coherence cancels the resonant absorption of the medium almost completely, but preserves the dispersion anomalous and very high. As a result, a superluminal light pulse propagation can be observed in the sense that the peak of the transmitted pulse exits the medium before the peak of the incident pulse enters. There is no violation of causality and energy conservation. Moreover, the superluminal effects are prominently manifested in the reshaping of pulse, which is caused by the intensity-dependent pulse velocity. Unlike the shock wave formation in a nonlinear medium with normal dispersion, here, the self-steepening of the pulse trailing edge takes place due to the fact that the more intense parts of the pulse travel slower. The predicted effect can be easily observed in the well known schemes employed for studying of nonlinear magneto-optical rotation. The upper bound of sample length is found from the criterion that the pulse self-steepening and group-advance time are observable without pulse distortion caused by the group-velocity dispersion. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0209/0209036v1.pdf"}
{"id": "physics0302009", "abstract": "  We present a new method to extract distance and orientation dependent potentials between amino acid side chains using a database of protein structures and the standard Boltzmann device. The importance of orientation dependent interactions is first established by computing orientational order parameters for proteins with alpha-helical and beta-sheet architecture. Extraction of the anisotropic interactions requires defining local reference frames for each amino acid that uniquely determine the coordinates of the neighboring residues. Using the local reference frames and histograms of the radial and angular correlation functions for a standard set of non-homologue protein structures, we construct the anisotropic pair potentials. The performance of the orientation dependent potentials was studied using a large database of decoy proteins. The results demonstrate that the new distance and orientation dependent residue-residue potentials present a significantly improved ability to recognize native folds from a set of native and decoy protein structures. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0302/0302009v1.pdf"}
{"id": "physics0304115", "abstract": "  The effect of three-body interatomic contributions in the equation of state of 4He are investigated. A recent two-body potential together with the Cohen and Murrell (Chem. Phys. Lett. 260, 371 (1996)) three-body potential are applied to describe bulk helium. The triple-dipole dispersion and exchange energies are evaluated subjected only to statistical uncertainties. An extension of the diffusion Monte Carlo method is applied in order to compute very small energies differences. The results show how the three-body contributions affects the ground-state energy, the equilibrium, melting and freezing densities. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0304/0304115v1.pdf"}
{"id": "physics0401008", "abstract": "  The concept of a plane scatterer that was developed earlier for scalar waves is generalized so that polarization of light is included. Starting from a Lippmann-Schwinger formalism for vector waves, we show that the Green function has to be regularized before T-matrices can be defined in a consistent way. After the regularization, optical modes and Green functions are determined exactly for finite structures built up of an arbitrary number of parallel planes, at arbitrary positions, and where each plane can have different optical properties. The model is applied to the special case of finite crystals consisting of regularly spaced identical planes, where analytical methods can be taken further and only light numerical tasks remain. The formalism is used to calculate position- and orientation-dependent spontaneous-emission rates inside and near the finite photonic crystals. The results show that emission rates and reflection properties can differ strongly for scalar and for vector waves. The finite size of the crystal influences the emission rates. For parallel dipoles close to a plane, emission into guided modes gives rise to a peak in the frequency-dependent emission rate. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0401/0401008v1.pdf"}
{"id": "physics0403135", "abstract": "  Considerable insights can be obtained regarding the nature of highly excited states by computing the eigenbasis expectation values of the resonance operators associated with an effective spectroscopic Hamiltonian. The expectation values are related to the parametric derivative of the eigenvalues with respect to specific resonance strengths i.e., level velocities.Sensitivity of the level velocities to the existence of closed orbits in the underlying classical phase space provides for a dimensionality independent route to a dynamical assignment of the states. In this letter, taking CHBrClF (polyad P=5) and the [16,0]^g+ bend polyad of C_2H_2 as examples, we show that the level velocities can signal the birth of new modes and highlight sequences of localized eigenstates. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0403/0403135v1.pdf"}
{"id": "physics0410187", "abstract": "  A new type of laser photodetachment (LPD) technique has been developed for the measurement of electron sheath thickness around an electrostatic probe and for the measurement of the length of collection region of photodetached electrons (PDE). When a thickness of the sheath formed around an electrostatic probe is thicker than about 0.1 mm, modification of the temporal evolution of the LPD signal is observed. By making use of the modification, we evaluated sheath thickness around a cylindrical probe in the existence of the magnetic field of 15 mT. It was found that the thickness of electron sheath along the magnetic field was comparable to the calculated plane-parallel Child-Langmuir sheath thickness when the probe-bias voltage was high. Furthermore, by inserting a small screening object in the laser beam channel, we can measure the sheath thickness from the modification of LPD signal. From the variation of the signal intensity as scanning the screening object perpendicular to the laser beam channel, we can observe the collection region of photodetached electrons, because this procedure changes the relative displacement between shadow and the probe electrode. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0410/0410187v1.pdf"}
{"id": "physics0411212", "abstract": "  A novel high-throughput second-order-correlation measurement system is developed which records and makes use of all the arrival times of photons detected at both start and stop detectors. This system is suitable particularly for a light source having a high photon flux and a long coherence time since it is more efficient than conventional methods by an amount equal to the product of the count rate and the correlation time of the light source. We have used this system in carefully investigating the dead time effects of detectors and photon counters on the second-order correlation function in the two-detector configuration. For a non-stationary light source, distortion of original signal was observed at high photon flux. A systematic way of calibrating the second-order correlation function has been devised by introducing a concept of an effective dead time of the entire measurement system. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0411/0411212v3.pdf"}
{"id": "physics0504075", "abstract": "  A new type of high-impedance surfaces (HIS) has been introduced by C.R. Simovski et al. recently. In this paper, we propose to use such layers as artificial magnetic materials in the design of patch antennas. The new HIS is simulated and patch antennas partially filled by these composite layers are measured in order to test how much the antenna dimensions can be reduced. In order to experimentally investigate the frequency behavior of the material, different sizes of the patches are designed and tested with the same material layer. Also the height of the patch is changed in order to find the best possible position for minimizing the antenna size. This composite layer of an artificial magnetic material has made the antenna smaller while keeping the bandwidth characteristics of the antenna about the same. About 40", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0504/0504075v1.pdf"}
{"id": "physics0510239", "abstract": "  Many social and biological networks consist of communities - groups of nodes within which connections are dense, but between which connections are sparser. Recently, there has been considerable interest in designing algorithms for detecting community structures in real-world complex networks. In this paper, we propose an evolving network model which exhibits community structure. The network model is based on the inner-community preferential attachment and inter-community preferential attachment mechanisms. The degree distributions of this network model are analyzed based on a mean-field method. Theoretical results and numerical simulations indicate that this network model has community structure and scale-free properties. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0510/0510239v1.pdf"}
{"id": "physics0602101", "abstract": "  We report the results of experiments that examined the dependence of the dripping dynamics of a leaky faucet on the orifice diameter. The transition of the dripping frequency between periodic and chaotic states was found to depend on the orifice diameter. We suggest a theoretical explanation for these transitions based on drop formation time scales. In addition, short-range anti-correlations were measured in the chaotic region. These too showed a dependence on the faucet diameter. Finally, a comparison was done between the experimental results with a one-dimensional model for drop formation. Quantitative agreement was found between the simulations and the experimental results. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0602/0602101v1.pdf"}
{"id": "physics0607231", "abstract": "  Computational methods for electromagnetic and light scattering can be used for the calculation of optical forces and torques. Since typical particles that are optically trapped or manipulated are on the order of the wavelength in size, approximate methods such as geometric optics or Rayleigh scattering are inapplicable, and solution or either the Maxwell equations or the vector Helmholtz equation must be resorted to. Traditionally, such solutions were only feasible for the simplest geometries; modern computational power enable the rapid solution of more general–but still simple–geometries such as axisymmetric, homogeneous, and isotropic scatterers. However, optically-driven micromachines necessarily require more complex geometries, and their computational modelling thus remains in the realm of challenging computational problems. We review our progress towards efficient computational modelling of optical tweezers and micromanipulation, including the trapping and manipulation of complex structures such as optical micromachines. In particular, we consider the exploitation of symmetry in the modelling of such devices. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0607/0607231v1.pdf"}
{"id": "physics0611236", "abstract": "  In order to better understand energy estimation of electromagnetic showers in segmented calorimeters, detailed Geant4 simulation studies of electromagnetic showers in the energy range 1–100 GeV in CsI have been performed. When sampled in layers of 1.99 cm thickness, corresponding to 1.08 radiation lengths, the energy fluctuations in the samples show distributions that vary significantly with depth. The energy distributions are similar for incident electrons and photons and were found to change systematically along the shower, varying little with the initial energy. Three probability distributions have been fitted to the data: negative binomial, log-normal and Gaussian distributions, none of which gives a good fit over the full shower length. The obtained parameterizations might be useful in the use of the maximum likelihood method for estimating the energy. Two methods for estimating the energy have also been studied. One method is based on fitting individual longitudinal shower profiles with a Γ-function, the other one corrects the measured energy for leakage by utilizing the energy deposited in the last layer. Our simulations indicate that the last-layer correction method applied to photons and electrons of 1 and 10 GeV gives about a factor of 2 improvement in the energy resolution. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0611/0611236v1.pdf"}
{"id": "physics0611256", "abstract": "  Highly dispersive photonic band-gap-edge optofluidic biosensors are studied theoretically. We demonstrate that these structures are strongly sensitive to the refractive index of the liquid, which is used to tune dispersion of the photonic crystal. The upper frequency band-gap edge shifts about 1.8 nm for dn=0.002, which is quite sensitive. Results from transmission spectra agree well with those obtained from the band structure theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0611/0611256v1.pdf"}
{"id": "physics0612020", "abstract": "  We report the results of theoretical and numerical analysis of the crystalline undulators planned to be used in the experiments which are the part of the ongoing PECU project [1]. The goal of such an analysis was to define the parameters (different from those pre-set by the experimental setup) of the undulators which ensure the highest yield of photons of specified energies. The calculations were performed for 0.6 and 10 GeV positrons channeling through periodically bent Si and Si_1-xGe_x crystals. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0612/0612020v1.pdf"}
{"id": "physics0701238", "abstract": "  Measurements of optical turbulence time series data using unattended instruments over long time intervals inevitably lead to data drop-outs or degraded signals. We present a comparison of methods using both Principal Component Analysis, which is also known as the Karhunen–Loeve decomposition, and ARIMA that seek to correct for these event-induced and mechanically-induced signal drop-outs and degradations. We report on the quality of the correction by examining the Intrinsic Mode Functions generated by Empirical Mode Decomposition. The data studied are optical turbulence parameter time series from a commercial long path length optical anemometer/scintillometer, measured over several hundred metres in outdoor environments. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0701/0701238v1.pdf"}
{"id": "physics0701332", "abstract": "  The dynamics of transient electric fields generated by the interaction of high intensity laser pulses with underdense plasmas has been studied experimentally with the proton projection imaging technique. The formation of a charged channel, the propagation of its front edge and the late electric field evolution have been characterised with high temporal and spatial resolution. Particle-in-cell simulations and an electrostatic, ponderomotive model reproduce the experimental features and trace them back to the ponderomotive expulsion of electrons and the subsequent ion acceleration. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0701/0701332v3.pdf"}
{"id": "physics0702169", "abstract": "  Variational MonteCarlo and Diffusion MonteCarlo calculations have been carried out for cations like Li^+, Na^+ and K^+ as dopants of small helium clusters over a range of cluster sizes up to about 12 solvent atoms. The interaction has been modelled through a sum-of-potential picture that disregards higher order effects beyond atom-atom and atom-ion contributions. The latter were obtained from highly correlated ab-initio calculations over a broad range of interatomic distances.   This study focuses on two of the most striking features of the microsolvation in a quantum solvent of a cationic dopant: electrostriction and snowball effects. They are here discussed in detail and in relation with the nanoscopic properties of the interaction forces at play within a fully quantum picture of the clusters features. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0702/0702169v1.pdf"}
{"id": "physics9806012", "abstract": "  We present a detailed study of the effects of the initial distribution on the kinetic evolution of the irreversible reaction A+B -> 0 in one dimension. Our analytic as well as numerical work is based on a reaction-diffusion model of this reaction. We focus on the role of initial density fluctuations in the creation of the macroscopic patterns that lead to the well-known kinetic anomalies in this system. In particular, we discuss the role of the long wavelength components of the initial fluctuations in determining the long-time behavior of the system. We note that the frequently studied random initial distribution is but one of a variety of possible distributions leading to interesting anomalous behavior. Our discussion includes an initial distribution with correlated A-B pairs and one in which the initial distribution forms a fractal pattern. The former is an example of a distribution whose long wavelength components are suppressed, while the latter exemplifies one whose long wavelength components are enhanced, relative to those of the random distribution. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/9806/9806012v1.pdf"}
{"id": "physics9806020", "abstract": "  The Faddeev equations for the atomic helium-trimer systems are solved numerically with high accuracy both for the most sophisticated realistic potentials available and for simple phenomenological potentials. An efficient numerical procedure is described. The large-distance asymptotic behavior, crucial for weakly bound three-body systems, is described almost analytically for arbitrary potentials. The Efimov effect is especially considered. The geometric structures of the bound states are quantitatively investigated. The accuracy of the schematic models and previous computations is comparable, i.e. within 20", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/9806/9806020v1.pdf"}
{"id": "physics9806034", "abstract": "  The multigrid algorithm is a multilevel approach to accelerate the numerical solution of discretized differential equations in physical problems involving long-range interactions. Multiresolution analysis of wavelet theory provides an efficient representation of functions which exhibit localized bursts of short length-scale behavior. Applications such as computing the electrostatic field in and around a molecule should benefit from both approaches. In this work, we demonstrate how a novel interpolating wavelet transform, which in itself is the synthesis of finite element analysis and wavelet theory, may be used as the mathematical bridge to connect the two approaches. The result is a specialized multigrid algorithm which may be applied to problems expressed in wavelet bases. With this approach, interpolation and restriction operators and grids for the multigrid algorithm are predetermined by an interpolating multiresolution analysis. We will present the new method and contrast its efficiency with standard wavelet and multigrid approaches. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/9806/9806034v1.pdf"}
{"id": "physics9812019", "abstract": "  As part of a general study of the time-dependent local density approximation (TDLDA), we here report calculations of optical activity of chiral molecules. The theory automatically satisfies sum rules and the Kramers-Kronig relation between circular dichroism and optical rotatory power. We find that the theory describes the measured circular dichroism of the lowest states in methyloxirane with an accuracy of about a factor of two. In the chiral fullerene C_76 the TDLDA provides a consistent description of the optical absorption spectrum, the circular dichroism spectrum, and the optical rotatory power, except for an overall shift of the theoretical spectrum. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/9812/9812019v1.pdf"}
{"id": "q-bio0401024", "abstract": "  Based on a recently proposed non-equilibrium mechanism for spatial pattern formation [cond-mat/0312366] we study how morphogenesis can be controlled by locally coupled discrete dynamical networks, similar to gene regulation networks of cells in a developing multicellular organism. As an example we study the developmental problem of domain formation and proportion regulation in the presence of noise and cell flow. We find that networks that solve this task exhibit a hierarchical structure of information processing and are of similar complexity as developmental circuits of living cells. A further focus of this paper is a detailed study of noise-induced dynamics, which is a major ingredient of the control dynamics in the developmental network model. A master equation for domain boundary readjustments is formulated and solved for the continuum limit. Evidence for a first order phase transition in equilibrium domain size at vanishing noise is given by finite size scaling. A second order phase transition at increased cell flow is studied in a mean field approximation. Finally, we discuss potential applications. ", "pdf_url": "gs://arxiv-dataset/arxiv/q-bio/pdf/0401/0401024v1.pdf"}
{"id": "q-bio0509027", "abstract": "  We study the stochastic dynamics of sequences evolving by single site mutations, segmental duplications, deletions, and random insertions. These processes are relevant for the evolution of genomic DNA. They define a universality class of non-equilibrium 1D expansion-randomization systems with generic stationary long-range correlations in a regime of growing sequence length. We obtain explicitly the two-point correlation function of the sequence composition and the distribution function of the composition bias in sequences of finite length. The characteristic exponent χ of these quantities is determined by the ratio of two effective rates, which are explicitly calculated for several specific sequence evolution dynamics of the universality class. Depending on the value of χ, we find two different scaling regimes, which are distinguished by the detectability of the initial composition bias. All analytic results are accurately verified by numerical simulations. We also discuss the non-stationary build-up and decay of correlations, as well as more complex evolutionary scenarios, where the rates of the processes vary in time. Our findings provide a possible example for the emergence of universality in molecular biology. ", "pdf_url": "gs://arxiv-dataset/arxiv/q-bio/pdf/0509/0509027v1.pdf"}
{"id": "q-bio0512045", "abstract": "  How cooperation emerges in human societies is still a puzzle. Evolutionary game theory has been the standard framework to address this issue. In most models, every individual plays with all others, and then reproduce and die according to what they earn. This amounts to assuming that selection takes place at a slow pace with respect to the interaction time scale. We show that, quite generally, if selection speeds up, the evolution outcome changes dramatically. Thus, in games such as Harmony, where cooperation is the only equilibrium and the only rational outcome, rapid selection leads to dominance of defectors. Similar non trivial phenomena arise in other binary games and even in more complicated settings such as the Ultimatum game. We conclude that the rate of selection is a key element to understand and model the emergence of cooperation, and one that has so far been overlooked. ", "pdf_url": "gs://arxiv-dataset/arxiv/q-bio/pdf/0512/0512045v1.pdf"}
{"id": "q-bio0602016", "abstract": "  We study a Langevin equation derived from the Michaelis-Menten (MM) phenomenological scheme for catalysis accompanying a spontaneous replication of molecules, which may serve as a simple model of cell-mediated immune surveillance against cancer. We examine how two different and statistically independent sources of noise - dichotomous multiplicative noise and additive Gaussian white noise - influence the population's extinction time. This quantity is identified as the mean first passage time of the system across the zero population state. We observe the effects of resonant activation (RA) and noise-enhanced stability (NES) and we report the evidence for competitive co-occurrence of both phenomena in a given regime of noise parameters. We discuss the statistics of first passage times in this regime and the role of different pseudo-potential profiles on the RA and NES phenomena. The RA/NES coexistence region brings an interesting interpretation for the growth kinetics of cancer cells population, as the NES effect enhancing the stability of the tumoral state becomes strongly reduced by the RA phenomenon. ", "pdf_url": "gs://arxiv-dataset/arxiv/q-bio/pdf/0602/0602016v2.pdf"}
{"id": "quant-ph0002059", "abstract": "  It is well known that the result of any phase measurement on an optical mode made using linear optics has an introduced uncertainty in addition to the intrinsic quantum phase uncertainty of the state of the mode. The best previously published technique [H. M. Wiseman and R.B. Killip, Phys. Rev. A 57, 2169 (1998)] is an adaptive technique that introduces a phase variance that scales as n^-1.5, where n is the mean photon number of the state. This is far above the minimum intrinsic quantum phase variance of the state, which scales as n^-2. It has been shown that a lower limit to the phase variance that is introduced scales as ln(n)/n^2. Here we introduce an adaptive technique that attains this theoretical lower limit. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0002/0002059v2.pdf"}
{"id": "quant-ph0009115", "abstract": "  Two particles that are entangled with respect to continuous variables such as position and momentum exhibit a variety of nonclassical features. First, measurement of one particle projects the other particle into the state that is the complex conjugate of the state of the first particle, i.e., measurement of one particle projects the other particle into the time-reversed state. Second, continuous-variable entanglement can be used to implement a quantum \"magic bullet\": when one particle manages to pass through a scattering potential, then no matter how low the probability of this event, the second particle will also pass through a related scattering potential with probability one. This phenomenon is investigated in terms of the original EPR state, and experimental realizations are suggested in terms of entangled photon states. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0009/0009115v1.pdf"}
{"id": "quant-ph0011083", "abstract": "  The role of the off-diagonal density matrix elements of the entangled pair is investigated in quantum teleportation of a qbit. The dependence between them and the off-diagonal elements of the teleported density matrix is shown to be linear. In this way the ideal quantum teleportation is related to an entirely classical communication protocol: the one-time pad cypher. The latter can be regarded as the classical counterpart of Bennett's quantum teleportation scheme. The quantum-to-classical transition is demonstrated on the statistics of a gedankenexperiment. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0011/0011083v2.pdf"}
{"id": "quant-ph0105086", "abstract": "  We investigate the quantum-classical transition in the delta-kicked rotor and the attainment of the classical limit in terms of measurement-induced state-localization. It is possible to study the transition by fixing the environmentally induced disturbance at a sufficiently small value, and examining the dynamics as the system is made more macroscopic. When the system action is relatively small, the dynamics is quantum mechanical and when the system action is sufficiently large there is a transition to classical behavior. The dynamics of the rotor in the region of transition, characterized by the late-time momentum diffusion coefficient, can be strikingly different from both the purely quantum and classical results. Remarkably, the early time diffusive behavior of the quantum system, even when different from its classical counterpart, is stabilized by the continuous measurement process. This shows that such measurements can succeed in extracting essentially quantum effects. The transition regime studied in this paper is accessible in ongoing experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0105/0105086v2.pdf"}
{"id": "quant-ph0106082", "abstract": "  We consider the dynamics of a system coupled to a thermal bath, going beyond the standard two-level system through the addition of an energy excitation degree of freedom. Further extensions are to systems containing many fermions, with the master equations modified to take Fermi-Dirac statistics into account, and to potentials with a time-dependent bias that induce resonant avoided crossing transitions. The limit Q →∞, where the interaction rate with the bath is much greater than all free oscillation rates for the system, is interrogated. Two behaviors are possible: freezing (quantum Zeno effect) or synchronization (motional narrowing). We clarify the conditions that give rise to each possibility, making an explicit connection with quantum measurement theory. We compare the evolution of quantal coherence for the two cases as a function of Q, noting that full coherence is restored as Q →∞. Using an extended master equation, the effect of system-bath interactions on entanglement in bipartite system states is computed. In particular, we show that the sychronization case sees bipartite system entanglement fully preserved in the large Q limit. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0106/0106082v3.pdf"}
{"id": "quant-ph0106151", "abstract": "  We consider the simple hypothesis of letting quantum systems have an inherent random nature. Using well-known stochastic methods we thus derive a stochastic evolution operator which let us define a stochastic density operator whose expectation value under certain conditions satisfies a Lindblad equation. As natural consequences of the former assumption decoherence and spontaneous emission processes are obtained under the same conceptual scheme. A temptative solution for the preferred basis problem is suggested. All this is illustrated with a comprehensive study of a two-level quantum system evolution. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0106/0106151v1.pdf"}
{"id": "quant-ph0204072", "abstract": "  We analyze the formation of polarization-squeezed light in a medium with electronic Kerr nonlinearity. Quantum Stokes parameters are considered and the spectra of their quantum fluctuations are investigated. It is established that the frequency at which the suppression of quantum fluctuations is the greatest can be controlled by adjusting the linear phase difference between pulses. We shown that by varying the intensity or the nonlinear phase shift per photon for one pulse, one can effectively control the suppression of quantum fluctuations of the quantum Stokes parameters. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0204/0204072v2.pdf"}
{"id": "quant-ph0210122", "abstract": "  We show the possibility to entangle radiation modes through a simple reflection on a moving mirror. The model of an optical cavity having a movable end mirror, and supporting different modes is employed. The mechanical motion of the mirror mediates information between the modes leading to an effective mode-mode interaction. We characterize the modes' entanglement on the basis of recent separability criteria. The effect of the thermal noise associate to the mirror's motion is accounted for. Then, we evaluate the performances of such ponderomotive entanglement in possible applications like teleportation and telecloning. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0210/0210122v2.pdf"}
{"id": "quant-ph0309047", "abstract": "  We refine the notion of concurrence in this paper by a redefinition of the concept. The new definition is simpler, computationally straight forward, and allows the concurrence to be directly read off from the state. It has all the positive features of the definiton given by Wootters over and above which it can discriminate between different systems to which the Wootters prescription would assign the same value. Finally, the definiton leads to a natural extension of the notion to multiqubit concurrence, which we illustrate with examples from quantum error correction codes. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0309/0309047v2.pdf"}
{"id": "quant-ph0309185", "abstract": "  Extending the eavesdropping strategy devised by Zhang, Li and Guo [Phys. Rev. A 63, 036301 (2001)], we show that the multiparty quantum communication protocol based on entanglement swapping, which was proposed by Cabello [quant-ph/0009025], is not secure. We modify the protocol so that entanglement swapping can secure multiparty quantum communication, such as multiparty quantum key distribution and quantum secret sharing of classical information, and show that the modified protocol is secure against the Zhang-Li-Guo's strategy for eavesdropping as well as the basic intercept-resend attack. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0309/0309185v2.pdf"}
{"id": "quant-ph0312216", "abstract": "  The maximum rates for information transmission through noisy quantum channels has primarily been developed for memoryless channels, where the noise on each transmitted state is treated as independent. Many real world communication channels experience noise which is modelled better by errors that are correlated between separate channel uses. In this paper, upper bounds on the classical information capacities of a class of quantum memory channels are derived. The class of channels consists of indecomposable quantum memory channels, a generalization of classical indecomposable finite-state channels. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0312/0312216v2.pdf"}
{"id": "quant-ph0503207", "abstract": "  For entangled states of light both the amount of entanglement and the sensitivity to noise generally increase with the number of photons in the state. The entanglement-sensitivity tradeoff is investigated for a particular set of states, multi-dimensional entangled coherent states. Those states possess an arbitrarily large amount of entanglement E provided the number of photons is at least of order 2^2E. We calculate how fast that entanglement decays due to photon absorption losses and how much entanglement is left. We find that for very small losses the amount of entanglement lost is equal to 2/log(2)≈ 2.89 ebits per absorbed photon, irrespective of the amount of pure-state entanglement E one started with. In contrast, for larger losses it tends to be the remaining amount of entanglement that is independent of E. This may provide a useful strategy for creating states with a fixed amount of entanglement. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0503/0503207v1.pdf"}
{"id": "quant-ph0506148", "abstract": "  We address the problem of spring-like coupling between bosons in an open chain configuration where the counter-rotating terms are explicitly included. We show that fruitful insight can be gained by decomposing the time-evolution operator of this problem into a pattern of linear-optics elements. This allows us to provide a clear picture of the effects of the counter-rotating terms in the important problem of long-haul entanglement distribution. The analytic control over the variance matrix of the state of the bosonic register allows us to track the dynamics of the entanglement. This helps in designing a global addressing scheme, complemented by a proper initialization of the register, which quantitatively improves the entanglement between the extremal oscillators in the chain, thus providing a strategy for feasible long distance entanglement distribution. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0506/0506148v1.pdf"}
{"id": "quant-ph0509207", "abstract": "  In order to quantify quantum entanglement in two impurity Kondo systems, we calculate the concurrence, negativity, and von Neumann entropy. The entanglement of the two Kondo impurities is shown to be determined by two competing many-body effects, the Kondo effect and the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction, I. Due to the spin-rotational invariance of the ground state, the concurrence and negativity are uniquely determined by the spin-spin correlation between the impurities. It is found that there exists a critical minimum value of the antiferromagnetic correlation between the impurity spins which is necessary for entanglement of the two impurity spins. The critical value is discussed in relation with the unstable fixed point in the two impurity Kondo problem. Specifically, at the fixed point there is no entanglement between the impurity spins. Entanglement will only be created (and quantum information processing (QIP) be possible) if the RKKY interaction exchange energy, I, is at least several times larger than the Kondo temperature, T_K. Quantitative criteria for QIP are given in terms of the impurity spin-spin correlation. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0509/0509207v1.pdf"}
{"id": "quant-ph0510117", "abstract": "  We consider a mass-less manifestly covariant linear Schrödinger equation. First, we show that it possesses a class of non-dispersive soliton solution with finite-size spatio-temporal support inside which the quantum amplitude satisfies the Klein-Gordon equation with finite emergent mass. We then proceed to interpret the soliton wave function as describing a particle with finite mass, energy and momentum. Inside the spatio-temporal support, the wave function shows spatio-temporal internal vibration with angular frequency and wave number that are determined by the energy-momentum of the particle as firstly conjectured by de Broglie. Imposing resonance of the internal vibration inside the spatio-temporal support leads to Planck-Einstein quantization of energy-momentum. The first resonance mode is shown to recover the classical energy-momentum relation developed in special relativity. We further show that the linearity of the Schrödinger equation allows one to construct many solitons solution through superposition, each describing a particle with various masses, energies and momenta. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0510/0510117v3.pdf"}
{"id": "quant-ph0606167", "abstract": "  We construct a quantum algorithm to approximate efficiently the colored Jones polynomial of the plat presentation of any oriented link L at a fixed root of unity q. Our construction is based on SU(2) Chern-Simons topological quantum field theory (and associated Wess-Zumino-Witten conformal field theory) and exploits the q-deformed spin network as computational background.   As proved in (S. Garnerone, A. Marzuoli, M. Rasetti, quant-ph/0601169), the colored Jones polynomial can be evaluated in a number of elementary steps, bounded from above by a linear function of the number of crossings of the link, and polynomially bounded with respect to the number of link strands. Here we show that the Kaul unitary representation of colored oriented braids used there can be efficiently approximated on a standard quantum circuit. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0606/0606167v1.pdf"}
{"id": "quant-ph0701089", "abstract": "  Cloning of observables, unlike standard cloning of states, aims at copying the information encoded in the statistics of a class of observables rather then on quantum states themselves. In such a process the emphasis is on the quantum operation (evolution plus measurement) necessary to retrieve the original information. We analyze, for qubit systems, the cloning of a class generated by two noncommuting observables, elucidating the relationship between such a process and joint measurements. This helps in establishing an optimality criterion for cloning of observables. We see that, even if the cloning machine is designed to act on the whole class generated by two noncommuting observables, the same optimal performances of a joint measurement can be attained. Finally, the connection with state dependent cloning is enlightened. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0701/0701089v1.pdf"}
{"id": "quant-ph0703228", "abstract": "  By investigating the evolution of a moving spin-1/2 Dirac electron coupled with a background magnetic noise, we demonstrate that the effects of special relativity will significantly modify the decoherence properties of the spin state. The dephasing could be much suppressed, and for a sufficiently long time the decoherence even seems to halt. This interesting phenomenon stems from the dressed environment induced by special relativity. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0703/0703228v2.pdf"}
{"id": "quant-ph9810018", "abstract": "  The quantum statistics of damped optical solitons is studied using cumulant-expansion techniques. The effect of absorption is described in terms of ordinary Markovian relaxation theory, by coupling the optical field to a continuum of reservoir modes. After introduction of local bosonic field operators and spatial discretization pseudo-Fokker-Planck equations for multidimensional s-parameterized phase-space functions are derived. These partial differential equations are equivalent to an infinite set of ordinary differential equations for the cumulants of the phase-space functions. Introducing an appropriate truncation condition, the resulting finite set of cumulant evolution equations can be solved numerically. Solutions are presented in Gaussian approximation and the quantum noise is calculated, with special emphasis on squeezing and the recently measured spectral photon-number correlations [Spaelter et al., Phys. Rev. Lett. 81, 786 (1998)]. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/9810/9810018v3.pdf"}
{"id": "quant-ph9907049", "abstract": "  We propose a scheme for preparing an EPR state in position and momentum of a pair of distantly-separated trapped atoms. The scheme utilizes the entangled light fields output from a nondegenerate optical parametric amplifier. Quantum state exchange between these fields and the motional states of the trapped atoms is accomplished via interactions in cavity QED. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/9907/9907049v1.pdf"}
{"id": "quant-ph9907072", "abstract": "  Spin interferometry of the 4th order for independent polarized as well as unpolarized photons arriving simultaneously at a beam splitter and exhibiting spin correlation while leaving it, is formulated and discussed in the quantum approach. Beam splitter is recognized as a source of genuine singlet photon states. Also, typical nonclassical beating between photons taking part in the interference of the 4th order is given a polarization dependent explanation. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/9907/9907072v1.pdf"}
{"id": "0705.0044", "abstract": "  In this paper, memories built from components subject to transient faults are considered. A fault-tolerant memory architecture based on low-density parity-check codes is proposed and the existence of reliable memories for the adversarial failure model is proved. The proof relies on the expansion property of the underlying Tanner graph of the code. An equivalence between the Taylor-Kuznetsov (TK) scheme and Gallager B algorithm is established and the results are extended to the independent failure model. It is also shown that the proposed memory architecture has lower redundancy compared to the TK scheme. The results are illustrated with specific numerical examples. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.0044v1.pdf"}
{"id": "0705.2910", "abstract": "  In the framework of the internal shock scenario, we model the broadband prompt emission of gamma-ray bursts (GRBs) with emphasis on the GeV-TeV bands, utilizing Monte Carlo simulations that include various processes associated with electrons and protons accelerated to high energies. While inverse Compton emission from primary electrons is often dominant, different proton-induced mechanisms can also give rise to distinct high-energy components, such as synchrotron emission from protons, muons or secondary electrons/positrons injected via photomeson interactions. In some cases, they give rise to double spectral breaks that can serve as unique signatures of ultra-high-energy protons. We discuss the conditions favorable for such emission, and how they are related to the production of ultra-high-energy cosmic rays and neutrinos in internal shocks. Ongoing and upcoming observations by GLAST, atmospheric Cerenkov telescopes and other facilities will test these expectations and provide important information on the physical conditions in GRB outflows. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.2910v3.pdf"}
{"id": "0705.2912", "abstract": "  We report measurements of the optical gap in a GdN film at temperatures from 300 to 6K, covering both the paramagnetic and ferromagnetic phases. The gap is 1.31eV in the paramagnetic phase and red-shifts to 0.9eV in the spin-split bands below the Curie temperature. The paramagnetic gap is larger than was suggested by very early experiments, and has permitted us to refine a (LSDA+U)-computed band structure. The band structure was computed in the full translation symmetry of the ferromagnetic ground state, assigning the paramagnetic-state gap as the average of the majority- and minority-spin gaps in the ferromagnetic state. That procedure has been further tested by a band structure in a 32-atom supercell with randomly-oriented spins. After fitting only the paramagnetic gap the refined band structure then reproduces our measured gaps in both phases by direct transitions at the X point. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0705/0705.2912v7.pdf"}
{"id": "0706.1067", "abstract": "  We study the modes and stability of non - isothermal coronal loop models with different intensity values of the equilibrium magnetic field. We use an energy principle obtained via non - equilibrium thermodynamic arguments. The principle is expressed in terms of Hermitian operators and allow to consider together the coupled system of equations: the balance of energy equation and the equation of motion. We determine modes characterized as long - wavelength disturbances that are present in inhomogeneous media. This character of the system introduces additional difficulties for the stability analysis because the inhomogeneous nature of the medium determines the structure of the disturbance, which is no longer sinusoidal. Moreover, another complication is that we obtain a continuous spectrum of stable modes in addition to the discrete one. We obtain a unique unstable mode with a characteristic time that is comparable with the characteristic life-time observed for loops. The feasibility of wave-based and flow-based models is examined. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0706/0706.1067v1.pdf"}
{"id": "0706.3839", "abstract": "  We report radio observations, made with the Australia Telescope Compact Array, of the X-ray transient XTE J1701-462. This system has been classified as a new `Z' source, displaying characteristic patterns of behaviour probably associated with accretion onto a low magnetic field neutron star at close to the Eddington limit. The radio counterpart is highly variable, and was detected in six of sixteen observations over the period 2006 January – April. The coupling of radio emission to X-ray state, despite limited sampling, appears to be similar to that of other `Z' sources, in that there is no radio emission on the flaring branch. The mean radio and X-ray luminosities are consistent with the other Z sources for a distance of 5–15 kpc. The radio spectrum is unusually flat, or even inverted, in contrast to the related sources, Sco X-1 and Cir X-1, which usually display an optically thin radio spectrum. Deep wide-field observations indicate an extended structure three arcminutes to the south which is aligned with the X-ray binary. This seems to represent a significant overdensity of radio sources for the field and so, although a background source remains a strong possibility, we consider it plausible that this is a large-scale jet associated with XTE J1701-462. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0706/0706.3839v1.pdf"}
{"id": "0707.1598", "abstract": "  We present a theory describing trapping of the normally dispersive radiation by the Raman solitons in optical fibers. Frequency of the radiation component is continuously blue shifting, while the soliton is red shifting. Underlying physics of the trapping effect is in the existence of the inertial gravity-like force acting on light in the accelerating frame of reference. We present analytical calculations of the rate of the opposing frequency shifts of the soliton and trapped radiation and find it to be greater than the rate of the red shift of the bare Raman soliton. Our findings are essential for understanding of the continuous shift of the high frequency edge of the supercontinuum spectra generated in photonic crystal fibers towards higher frequencies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0707/0707.1598v2.pdf"}
{"id": "0708.2345", "abstract": "  We extend Tooru-Cohen analysis for nonequilirium steady state(NSS) of a Brownian particle to nonequilibrium oscillatory state (NOS) of Brownian particle by considering time dependent external drive protocol. We consider an unbounded charged Brownian particle in the presence of an oscillating electric field and prove work fluctuation theorem, which is valid for any initial distribution and at all times. For harmonically bounded and constantly dragged Brownian particle considered by Tooru and Cohen, work fluctuation theorem is valid for any initial condition(also NSS), but only in large time limit. We use Onsager-Machlup Lagrangian with a constraint to obtain frequency dependent work distribution function, and describe entropy production rate and properties of dissipation functions for the present system using Onsager-Machlup functional. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0708/0708.2345v1.pdf"}
{"id": "0708.2498", "abstract": "  There is a growing consensus that physics majors need to learn computational skills, but many departments are still devoid of computation in their physics curriculum. Some departments may lack the resources or commitment to create a dedicated course or program in computational physics. One way around this difficulty is to include computation in a standard upper-level physics course. An intermediate classical mechanics course is particularly well suited for including computation. We discuss the ways we have used computation in our classical mechanics courses, focusing on how computational work can improve students' understanding of physics as well as their computational skills. We present examples of computational problems that serve these two purposes. In addition, we provide information about resources for instructors who would like to include computation in their courses. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0708/0708.2498v1.pdf"}
{"id": "0709.4158", "abstract": "  Infrared spectroscopy in the mid- and far-infrared provides powerful diagnostics for studying the emission regions in active galaxies. The large variety of ionic fine structure lines can probe gas conditions in a variety of physical conditions, from highly ionized gas excited by photons originated by black hole accretion to gas photoionized by young stellar systems. The critical density and the ionization potential of these transitions allow to fully cover the density-ionization parameter space. Some examples of line ratios diagrams using both mid-infrared and far-infrared ionic fine structure lines are presented. The upcoming space observatory Herschel will be able to observe the far-infrared spectra of large samples of local active galaxies. Based on the observed near-to-far infrared emission line spectrum of the template galaxy NGC1068, are presented the predictions for the line fluxes expected for galaxies at high redshift. To observe spectroscopically large samples of distant galaxies, we will have to wait fot the future space missions, like SPICA and, ultimately, FIRI. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0709/0709.4158v1.pdf"}
{"id": "0711.4775", "abstract": "  As a model for gene and protein interactions we study a set for molecular catalytic reactions. The model is based on experimentally motivated interaction network topologies, and is designed to capture some key statistics of gene expression statistics. We impose a non-linearity to the system by a boundary condition which guarantees non-negative concentrations of chemical concentrations and study the system stability quantified by maximum Lyapunov exponents. We find that the non-negativity constraint leads to a drastic inflation of those regions in parameter space where the Lyapunov exponent exactly vanishes. We explain the finding as a self-organized critical phenomenon. The robustness of this finding with respect to different network topologies and the role of intrinsic molecular- and external noise is discussed. We argue that systems with inflated 'edges of chaos' could be much more easily favored by natural selection than systems where the Lyapunov exponent vanishes only on a parameter set of measure zero. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0711/0711.4775v1.pdf"}
{"id": "0712.0670", "abstract": "  Repeated measurements of a quantum particle to check its presence in a region of space was proposed long ago [G. R. Allcock, Ann. Phys. 53, 286 (1969)] as a natural way to determine the distribution of times of arrival at the orthogonal subspace, but the method was discarded because of the quantum Zeno effect: in the limit of very frequent measurements the wave function is reflected and remains in the original subspace. We show that by normalizing the small bits of arriving (removed) norm, an ideal time distribution emerges in correspondence with a classical local-kinetic-energy distribution. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0712/0712.0670v2.pdf"}
{"id": "0802.0456", "abstract": "  Extragalactic transient searches have historically been limited to looking for the appearance of new sources such as supernovae. It is now possible to carry out a new kind of survey that will do the opposite, that is, search for the disappearance of massive stars. This will entail the systematic observation of galaxies within a distance of 10 Mpc in order to watch  10^6 supergiants. Reaching this critical number ensures that something will occur yearly, since these massive stars must end their lives with a core collapse within  10^6 years. Using deep imaging and image subtraction it is possible to determine the fates of these stars whether they end with a bang (supernova) or a whimper (fall out of sight). Such a survey would place completely new limits on the total rate of all core collapses, which is critical for determining the validity of supernova models. It would also determine the properties of supernova progenitors, better characterize poorly understood optical transients, such as eta Carina-like mass ejections, find and characterize large numbers of Cepheids, luminous blue variables and eclipsing binaries, and allow the discovery of any new phenomena that inhabit this relatively unexplored parameter space. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.0456v2.pdf"}
{"id": "0802.1926", "abstract": "  CODEX and ESPRESSO are concepts for ultra-stable, high-resolution spectrographs at the E-ELT and VLT, respectively. Both instruments are well motivated by distinct sets of science drivers. However, ESPRESSO will also be a stepping stone towards CODEX both in a scientific as well as in a technical sense. Here we discuss this role of ESPRESSO with respect to one of the most exciting CODEX science cases, i.e. the dynamical determination of the cosmic expansion history. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.1926v1.pdf"}
{"id": "0802.2058", "abstract": "  A study is made of the behavior of massive black holes in disk galaxies that have received an impulsive kick from a merger or a sustained acceleration from an asymmetric jet. The motion of the gas, stars, dark matter, and massive black hole are calculated using the GADGET-2 simulation code. The massive black hole escapes the galaxy for kick velocities above about 600 km/s or accelerations above about 4*10^-8 cm/s^2 over time-scales of the order of 10^8 yr. For smaller velocity kicks or smaller accelerations, the black hole oscillates about the center of mass with a frequency which decreases as the kick velocity or acceleration increases. The black hole displacements may give rise to observable nonaxisymmetries in the morphology and dynamics of the stellar and gaseous disk of the galaxy. In some cases the dynamical center of the galaxy is seen to be displaced towards the direction of the BH acceleration with a characteristic “tongue–” shaped extension of the velocity contours on the side of the galaxy opposite the acceleration. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.2058v1.pdf"}
{"id": "0802.2429", "abstract": "  In this paper we introduce a new selection scheme in cellular genetic algorithms (cGAs). Anisotropic Selection (AS) promotes diversity and allows accurate control of the selective pressure. First we compare this new scheme with the classical rectangular grid shapes solution according to the selective pressure: we can obtain the same takeover time with the two techniques although the spreading of the best individual is different. We then give experimental results that show to what extent AS promotes the emergence of niches that support low coupling and high cohesion. Finally, using a cGA with anisotropic selection on a Quadratic Assignment Problem we show the existence of an anisotropic optimal value for which the best average performance is observed. Further work will focus on the selective pressure self-adjustment ability provided by this new selection scheme. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.2429v1.pdf"}
{"id": "0802.3612", "abstract": "  We consider the model of quantum computer, which is represented as a Ising spin lattice, where qubits (spin-half systems) are separated by the isolators (two spin-half systems). In the idle mode or at the single bit operations the total spin of isolators is 0. There are no need of complicated protocols for correcting the phase and probability errors due to permanent interaction between the qubits. We present protocols for implementation of universal quantum gates with the rectangular radio-frequency pulses. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0802/0802.3612v1.pdf"}
{"id": "0803.2277", "abstract": "  We study the effects of arbitrary laser pulse excitations on quantum correlation, entanglement and the role of quantum noise. The transient quantities are computed exactly using a method that provides exact solutions of the Langevin field operators for photon pairs produced by a double Raman atom driven by laser pulses. Short pulses with appropriate chirping, delay and/or detuning can generate broadband photon pairs and yield results that provide insights on how to generate very large nonclassical correlation. We find that short pulses are not favorable for entanglement. The quantity was previously found to be phase-sensitive and this is used with the pulse area concept to explain the rapid variations of entanglement with pulse width and strength. Photon correlation and entanglement are favored by exclusively two different initial conditions. Analysis reinforces our understanding of the two nonclassical concepts. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0803/0803.2277v1.pdf"}
{"id": "0803.4364", "abstract": "  Using the numerical path integral method we investigate the decoherence and relaxation of qubits in spin-boson (SB) and spin-intermediate harmonic oscillator (IHO)-bath (SIB) models. The cases that the environment baths with low and medium frequencies are investigated. It is shown that the qubits in SB and SIB models have the same decoherence and relaxation as the baths with low frequencies. However, the qubits in the two models have different decoherence and relaxation as the baths with medium frequencies. The decoherence and relaxation of the qubit in SIB model can be modulated through changing the coupling coefficients of the qubit-IHO and IHO-bath and the oscillation frequency of the IHO. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0803/0803.4364v1.pdf"}
{"id": "0804.0296", "abstract": "  We have developed a method 'time-frequency (TF) clustering' to find the burst gravitational waves for TAMA data analysis. TF clustering method on sonogram (spectrogram) shows some characteristics of short duration signal. Using parameters which represent the cluster shape, we can efficiently identify some predicted gravitational wave forms and can exclude typical unstable spike like noises due to detector instruments. The requirement of some parameters of cluster achieved roughly 50", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0804/0804.0296v1.pdf"}
{"id": "0804.4719", "abstract": "  This work is part of a project on weight bases for the irreducible representations of semisimple Lie algebras with respect to which the representation matrices of the Chevalley generators are given by explicit formulas. In the case of sl_n, the celebrated Gelfand-Tsetlin basis is the only such basis known. Using the setup of supporting graphs developed by Donnelly, we present a simple combinatorial proof of the Gelfand-Tsetlin formulas based on a rational function identity. Some properties of the Gelfand-Tsetlin basis are derived via an algorithm for solving certain equations on the lattice of semistandard Young tableaux. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0804/0804.4719v2.pdf"}
{"id": "0805.0498", "abstract": "  In a seminal paper from 1985, Sistla and Clarke showed that the model-checking problem for Linear Temporal Logic (LTL) is either NP-complete or PSPACE-complete, depending on the set of temporal operators used. If, in contrast, the set of propositional operators is restricted, the complexity may decrease. This paper systematically studies the model-checking problem for LTL formulae over restricted sets of propositional and temporal operators. For almost all combinations of temporal and propositional operators, we determine whether the model-checking problem is tractable (in P) or intractable (NP-hard). We then focus on the tractable cases, showing that they all are NL-complete or even logspace solvable. This leads to a surprising gap in complexity between tractable and intractable cases. It is worth noting that our analysis covers an infinite set of problems, since there are infinitely many sets of propositional operators. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0805/0805.0498v1.pdf"}
{"id": "0806.2888", "abstract": "  Networks of person-person contacts form the substrate along which infectious diseases spread. Most network-based studies of the spread focus on the impact of variations in degree (the number of contacts an individual has). However, other effects such as clustering, variations in infectiousness or susceptibility, or variations in closeness of contacts may play a significant role. We develop analytic techniques to predict how these effects alter the growth rate, probability, and size of epidemics and validate the predictions with a realistic social network. We find that (for given degree distribution and average transmissibility) clustering is the dominant factor controlling the growth rate, heterogeneity in infectiousness is the dominant factor controlling the probability of an epidemic, and heterogeneity in susceptibility is the dominant factor controlling the size of an epidemic. Edge weights (measuring closeness or duration of contacts) have impact only if correlations exist between different edges. Combined, these effects can play a minor role in reinforcing one another, with the impact of clustering largest when the population is maximally heterogeneous or if the closer contacts are also strongly clustered. Our most significant contribution is a systematic way to address clustering in infectious disease models, and our results have a number of implications for the design of interventions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0806/0806.2888v2.pdf"}
{"id": "0806.4909", "abstract": "  We review the status of Monte Carlo generators presently used for simulations of the large-angle Bhabha process at electron-positron colliders of moderately high energy (flavour factories), operating at centre-of-mass energies between about 1 GeV and 10 GeV. It is shown how the theoretical accuracy reached by present Bhabha programs for physics at flavour factories is at the level of 0.1", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0806/0806.4909v1.pdf"}
{"id": "0808.0778", "abstract": "  It was proposed that a double quantum dot can be used to be a detector of spin bias. Electron transport through a double quantum dot is investigated theoretically when a pure spin bias is applied on two conducting leads contacted to the quantum dot. It is found that the spin polarization in the left and right dots may be induced spontaneously while the intra-dot levels are located within the spin bias window and breaks the left-right symmetry of the two quantum dots. As a result, a large current emerges. For an open external circuit an charge bias instead of a charge current will be induced in equilibrium, which is believed to be measurable according to the current nanotechnology. This method may provide a practical and whole electrical approach to detect the spin bias (or the spin current) by measuring the charge bias or current in a double quantum dot. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.0778v1.pdf"}
{"id": "0808.1693", "abstract": "  We consider the phase transition of a string with tension _1 to a string with a smaller tension _2. The transition proceeds through quantum tunneling, and we calculate in arbitrary number of dimensions the pre-exponential factor multiplying the leading semiclassical exponential expression for the rate of the process. At _2=0 the found formula for the decay rate also describes a break up of a metastable string into two pieces. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.1693v1.pdf"}
{"id": "0808.2294", "abstract": "  We show that repeated sound waves in the intracluster medium (ICM) can be excited by a single inflation episode of an opposite bubble pair. To reproduce this behavior in numerical simulations the bubbles should be inflated by jets, rather than being injected artificially. The multiple sound waves are excited by the motion of the bubble-ICM boundary that is caused by vortices inside the inflated bubbles and the backflow (`cocoon') of the ICM around the bubble. These sound waves form a structure that can account for the ripples observed in the Perseus cooling flow cluster. We inflate the bubbles using slow massive jets, with either a wide opening angle or that are precessing. The jets are slow in the sense that they are highly sub-relativistic, v_j ∼ 0.01c-0.1c, and they are massive in the sense that the pair of bubbles carry back to the ICM a large fraction of the cooling mass, i.e., ∼ 1-50 M_⊙^-1. We use a two-dimensional axisymmetric (referred to as 2.5D) hydrodynamical numerical code (VH-1). ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0808/0808.2294v1.pdf"}
{"id": "0809.0553", "abstract": "  The recent discovery of the 2003EL61 collisional family in the Kuiper belt (Brown et al., 2007) is surprising because the formation of such a family is a highly improbable event in today's belt. Assuming Brown et al.'s estimate of the size of progenitors, we find that the probability that a Kuiper belt object was involved in such a collision since primordial times is less than roughly 0.001. In addition, it is not possible for the collision to have occurred in a massive primordial Kuiper belt because the dynamical coherence of the family would not have survived whatever event produced the currently observed orbital excitation. Here we suggest that the family is the result of a collision between two scattered disk objects. We show that the probability that a collision occurred between two such objects with sizes similar to those advocated in Brown et al. (2007) and that the center of mass of the resulting family is on an orbit typical of the Kuiper belt can be as large as 47", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.0553v1.pdf"}
{"id": "0809.1499", "abstract": "  The relativistic diffusion process of heavy quarks is formulated on the basis of the relativistic Langevin equation in Itô discretization scheme. The drag force inside the quark-gluon plasma (QGP) is parametrized according to the formula for the strongly coupled plasma obtained by the AdS/CFT correspondence. The diffusion dynamics of charm and bottom quarks in QGP is described by combining the Langevin simulation under the background matter described by the relativistic hydrodynamics. Theoretical calculations of the nuclear modification factor R_AA and the elliptic flow v_2 for the single electrons from the charm and bottom decays are compared with the experimental data from the relativistic heavy ion collisions. The R_AA for electrons with large transverse momentum (p_T > 3 GeV) indicates that the drag force from the QGP is as strong as the AdS/CFT prediction. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0809/0809.1499v3.pdf"}
{"id": "0810.2290", "abstract": "  We provide a physically meaningful picture of the nature of the ground state of the Cr8Ni compound in the regime where it is a spin singlet. According to this picture, the anisotropy of the Ni atom in the Cr ring induces a dimerization in the molecule that makes the ground state to stabilize in a Valence Bond Solid phase of virtual spins. We characterize rigorously this phase by means of a particular non-local order parameter denoted the generalized string order parameter. In the completely antiferromagnetic regime, the system becomes frustrated. We have performed a numerical real-time evolution study of the correlations between the spin of the Ni impurity and the rest of the spins in order to show the reaction of the system under this frustration. We provide results that manifestly show the agreement with the Valence Bond Solid picture introduced. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.2290v1.pdf"}
{"id": "0810.3561", "abstract": "  We present the result of the observation of the ultrafaint dwarf galaxy Willman 1 performed with the 17 m MAGIC telescope during 15.5 hr between March and May 2008. No significant γ-ray emission was found. We derived upper limits of the order of 10^-12 ph cm^-2 s^-1 on the integral flux above 100 GeV, which we compare with predictions from several of the established neutralino benchmark models in the mSUGRA parameter space. The neutralino annihilation spectra are defined after including the recently quantified contribution of internal bremsstrahlung from the virtual sparticles that mediate the annihilation. Flux boost factors of three orders of magnitude are required even in the most optimistic scenario to match our upper limits. However, uncertainties in the dark matter intrinsic and extrinsic properties (e.g., presence of substructures, Sommerfeld effect) may significantly reduce this gap. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.3561v3.pdf"}
{"id": "0810.3971", "abstract": "  We report the serendipitous discovery of an \"Einstein Ring\" in the optical band from the Sloan Digital Sky Survey (SDSS) data and associated four images of a background source. The lens galaxy appears to be a nearby dwarf spheroid at a redshift of 0.0375±0.002. The lensed quasar is at a redshift of 0.6842±0.0014 and its multiple images are distributed almost 360^o around the lens nearly along a ring of radius ∼6.\"0. Single component lens models require a mass of the galaxy of almost 10^12 M_⊙ within 6\".0 from the lens center. With the available data we are unable to determine the exact positions, orientations and fluxes of the quasar and the galaxy, though there appears evidence for a double or multiple merging image of the quasar. We have also detected strong radio and X-ray emissions from this system. It is indicative that this ring system may be embedded in a group or cluster of galaxies. This unique ring, by virtue of the closeness of the lens galaxy, offers possible probe to some of the key issues like mass-to-light ratio of intrinsically faint galaxies, existence of large scale magnetic fields in elliptical galaxies etc. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0810/0810.3971v1.pdf"}
{"id": "0811.0464", "abstract": "  We present an analysis leading to precise locations of the multicritical points for spin glasses on regular lattices. The conventional technique for determination of the location of the multicritical point was previously derived using a hypothesis emerging from duality and the replica method. In the present study, we propose a systematic technique, by an improved technique, giving more precise locations of the multicritical points on the square, triangular, and hexagonal lattices by carefully examining relationship between two partition functions related with each other by the duality. We can find that the multicritical points of the ± J Ising model are located at p_c = 0.890813 on the square lattice, where p_c means the probability of J_ij = J(>0), at p_c = 0.835985 on the triangular lattice, and at p_c = 0.932593 on the hexagonal lattice. These results are in excellent agreement with recent numerical estimations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0811/0811.0464v2.pdf"}
{"id": "0812.3271", "abstract": "  We report on our time-resolved CCD photometry during the 2005 June superoutburst of a WZ Sge-type dwarf nova candidate, ASAS 160048-4846.2. The ordinary superhumps underwent a complex evolution during the superoutburst. The superhump amplitude experienced a regrowth, and had two peaks. The superhump period decreased when the superhump amplitude reached to the first maximum, successively gradually increased until the second maximum of the amplitude, and finally decreased again. Investigating other SU UMa-type dwarf novae which show an increase of the superhump period, we found the same trend of the superhump evolution in superoutbursts of them. We speculate that the superhump regrowth in the amplitude has a close relation to the increase of the superhump period, and all of SU UMa-type dwarf novae with a superhump regrowth follow the same evolution of the ordinary superhumps as that of ASAS 160048-4846.2. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.3271v1.pdf"}
{"id": "0812.4625", "abstract": "  Any 8-qubit graph state belongs to one of the 101 equivalence classes under local unitary operations within the Clifford group. For each of these classes we obtain a representative which requires the minimum number of controlled-Z gates for its preparation, and calculate the Schmidt measure for the 8-partite split, and the Schmidt ranks for all bipartite splits. This results into an extension to 8 qubits of the classification of graph states proposed by Hein, Eisert, and Briegel [Phys. Rev. A 69, 062311 (2004)]. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0812/0812.4625v3.pdf"}
{"id": "0902.1740", "abstract": "  Astronomical data generally consists of 2 or more high-resolution axes, e.g., X,Y position on the sky or wavelength and position-along-one-axis (long-slit spectrometer). Analyzing these multi-dimension observations requires combining 3D source models (including velocity effects), instrument models, and multi-dimensional data comparison and fitting. A prototype of such a \"Beyond-XSPEC\" (Noble     Nowak, 2008) system is presented here using Chandra imag- ing and dispersed HETG grating data. Techniques used include: Monte Carlo event generation, chi-squared comparison, conjugate gradient fitting adapted to the Monte Carlo characteristics, and informative visualizations at each step. These simple baby steps of progress only scratch the surface of the computational potential that is available these days for astronomical analysis. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.1740v1.pdf"}
{"id": "0902.4777", "abstract": "  We investigate exceptional points, which are branch point singularities of two resonance eigenstates, in spectra of the hydrogen atom in crossed external electric and magnetic fields. A procedure to systematically search for exceptional points is presented, and their existence is proven. The properties of the branch point singularities are discussed with effective low-dimensional matrix models, their relation with avoided level crossings is analyzed, and their influence on dipole matrix elements and the photoionization cross section is investigated. Furthermore, the rare case of a connection between three resonances almost forming a triple-degeneracy in the form of a cubic root branch point is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0902/0902.4777v1.pdf"}
{"id": "0904.2724", "abstract": "  We have studied several radio galaxies at low radio frequencies using GMRT. Our prime motivation to detect faint radio emission at very low frequencies due to low energy electrons.   Our results provide evidence that there exists two classes of sources on morphological grounds. The first class is explained by the simple picture of spectral electron ageing but in the second class the low-frequency synchrotron emission fades (nearly) as rapidly as high-frequency synchrotron emission. In addition, in several sources, the spectra of low-surface-brightness features are flatter than the spectra of high-surface-brightness features, which suggests that either the simple picture of spectral electron ageing needs revision or we need to re-examine the formation mechanism of such sources.   The images and statistics, and the relevance of these results along with the role of GMRT in exploring several unknowns are presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0904/0904.2724v1.pdf"}
{"id": "0905.0387", "abstract": "  Quantum state transfer is a procedure, which allows to exchange quantum information between stationary qubit systems. It is anticipated that the transfer will find applications in solid-state quantum computing. In this contribution, we discuss the effects of various, physically relevant models of decoherence on a toy model of six qubit linearly coupled by the exchange interaction. In many cases we observe the advantage of the two-qubit encoding, which can be associated with the fact that this encoding does not require the state initialization. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.0387v1.pdf"}
{"id": "0905.0886", "abstract": "  The dynamics of vortex solitons in a BEC superfluid is studied. A quantum lattice-gas algorithm (localization-based quantum computation) is employed to examine the dynamical behavior of vortex soliton solutions of the Gross-Pitaevskii equation (phi^4 interaction nonlinear Schroedinger equation). Quantum turbulence is studied in large grid numerical simulations: Kolmogorov spectrum associated with a Richardson energy cascade occurs on large flow scales. At intermediate scales a k^-6 power law emerges, in a classical-quantum transition from vortex filament reconnections to Kelvin wave-acoustic wave coupling. The spontaneous exchange of intermediate vortex rings is observed. Finally, at very small spatial scales a k^-3 power law emerges, characterizing fluid dynamics occurring within the scale size of the vortex cores themselves, a characteristic Kelvin wave cascade region. Poincare recurrence is studied: in the free non-interacting system, a fast Poincare recurrence occurs for regular arrays of line vortices. The recurrence period is used to demarcate dynamics driving the nonlinear quantum fluid towards turbulence, since fast recurrence is an approximate symmetry of the nonlinear quantum fluid at early times. This class of quantum algorithms is useful for studying BEC superfluid dynamics over a broad range of wave numbers, from quantum flow to a pseudo-classical inviscid flow regime to a Kolmogorov inertial subrange. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0905/0905.0886v1.pdf"}
{"id": "0906.0029", "abstract": "  We summarize the results of previous research on the constraints imposed on quark masses by the anthropically-motivated requirement that there exist stable nuclei with the right charge to form complex molecules. We also mention an upper bound on the mass of the lightest lepton, derived from the requirement that such nuclei be stable against electron capture. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0906/0906.0029v1.pdf"}
{"id": "0907.3476", "abstract": "  We study rapidly accreting, gravitationally unstable disks with a series of global, three dimensional, numerical experiments using the code ORION. In this paper we conduct a numerical parameter study focused on protostellar disks, and show that one can predict disk behavior and the multiplicity of the accreting star system as a function of two dimensionless parameters which compare the disk's accretion rate to its sound speed and orbital period. Although gravitational instabilities become strong, we find that fragmentation into binary or multiple systems occurs only when material falls in several times more rapidly than the canonical isothermal limit. The disk-to-star accretion rate is proportional to the infall rate, and governed by gravitational torques generated by low-m spiral modes. We also confirm the existence of a maximum stable disk mass: disks that exceed  50", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.3476v1.pdf"}
{"id": "0907.4073", "abstract": "  We consider the stochastic background of gravitational waves produced during the radiation-dominated hot big bang as a constraint on the primordial density perturbation on comoving length scales much smaller than those directly probed by the cosmic microwave background or large-scale structure. We place weak upper bounds on the primordial density perturbation from current data. Future detectors such as BBO and DECIGO will place much stronger constraints on the primordial density perturbation on small scales. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0907/0907.4073v3.pdf"}
{"id": "0908.2488", "abstract": "  A multiple-graphene-layer (MGL) structure with a stack of GLs and a highly conducting bottom GL on SiC substrate pumped by optical radiation is considered as an active region of terahertz (THz) and far infrared (FIR) lasers with external metal mirrors. The dynamic conductivity of the MGL structure is calculated as a function of the signal frequency, the number of GLs, and the optical pumping intensity. The utilization of optically pumped MGL structures might provide the achievement of lasing with the frequencies of about 1 THz at room temperature due to a high efficiency. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0908/0908.2488v1.pdf"}
{"id": "0908.3939", "abstract": "  We revisit the problem of a single hole moving in the background of the two dimensional Heisenberg antiferromagnet. The hole is loosely bound by an impurity potential. We show that the bound state is generically a parity doublet: there are parametrically close bound states of opposite parity. Due to the degeneracy the bound state readily breaks local symmetries of the square lattice and this leads to formation of the long range spiral distortion of the antiferromagnetic background. A direct analogy with van der Waals forces in atomic physics is discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0908/0908.3939v1.pdf"}
{"id": "0909.0055", "abstract": "  Muons with a high transverse momentum (p_T) are produced in cosmic ray air showers via semileptonic decay of heavy quarks and the decay of high p_T kaons and pions. These high p_T muons have a large lateral separation from the shower core muon bundle. IceCube is well suited for the detection of high p_T muons. The surface shower array can determine the energy, core location and direction of the cosmic ray air shower while the in-ice array can reconstruct the energy and direction of the high p_T muon. This makes it possible to measure the decoherence function (lateral separation spectrum) at distances greater than 150 meters. The muon p_T can be determined from the muon energy (measured by dE/dx) and the lateral separation. The high p_T muon spectrum may also be calculated in a perturbative QCD framework; this spectrum is sensitive to the cosmic-ray composition. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.0055v1.pdf"}
{"id": "0909.0962", "abstract": "  Using observations made with the XMM-Newton Observatory, we report the first X-ray detection of the high magnetic field radio pulsar PSR B1916+14. We show that the X-ray spectrum of the pulsar can be well fitted with an absorbed blackbody with temperature in the range of 0.08-0.23 keV, or a neutron star hydrogen atmosphere model with best-fit effective temperature of ∼0.10 keV, higher than expected from fast cooling models. The origin of the likely thermal emission is not well constrained by our short observation and is consistent with initial cooling or return-current heating. We found no pulsations in these data and set a 1σ upper limit on the pulsed fraction in the 0.1–2 keV band of ∼0.7. Implications of these results for our understanding of the different observational properties of isolated neutron stars are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.0962v1.pdf"}
{"id": "0909.2792", "abstract": "  From recent high resolution observations obtained with the Swedish 1 m Solar Telescope in La Palma, we detect swaying motions of individual filament threads in the plane of the sky. The oscillatory character of these motions are comparable with oscillatory Doppler signals obtained from corresponding filament threads. Simultaneous recordings of motions in the line of sight and in the plane of the sky give information about the orientation of the oscillatory plane. These oscillations are interpreted in the context of the magnetohydrodynamic theory. Kink magnetohydrodynamic waves supported by the thread body are proposed as an explanation of the observed thread oscillations. On the basis of this interpretation and by means of seismological arguments, we give an estimation of the thread Alfvén speed and magnetic field strength by means of seismological arguments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.2792v1.pdf"}
{"id": "0909.3105", "abstract": "  In this paper we discuss the fluidity of the hot and dense QCD matter created in ultrarelativistic heavy ion collisions in comparison with various other fluids, and in particular suggest its possible supercriticality. After examining the proper way to compare non-relativistic and relativistic fluids from both thermodynamic and hydrodynamic perspectives, we propose a new fluidity measure which shows certain universality for a remarkable diversity of critical fluids. We then demonstrate that a fluid in its supercritical regime has its fluidity considerably enhanced. This may suggest a possible relationship between the seemingly good fluidity of the QCD matter produced in heavy ion collisions at center of mass energy of √(s)=200  AGeV and the supercriticality of this matter with respect to the Critical-End-Point on the QCD phase diagram. Based on such observation, we predict an even better fluidity of the matter to be created in heavy ion collisions at LHC energy and the loss of good fluidity at certain lower beam energy. Finally based on our criteria, we analyze the suitability of a hydrodynamic description for the fireball evolution in heavy ion collisions at various energies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0909/0909.3105v3.pdf"}
{"id": "0910.3523", "abstract": "  We use lattice Boltzmann simulations, in conjunction with Ewald summation methods, to investigate the role of hydrodynamic interactions in colloidal suspensions of dipolar particles, such as ferrofluids. Our work addresses volume fractions ϕ of up to 0.20 and dimensionless dipolar interaction parameters λ of up to 8. We compare quantitatively with Brownian dynamics simulations, in which many-body hydrodynamic interactions are absent. Monte Carlo data are also used to check the accuracy of static properties measured with the lattice Boltzmann technique. At equilibrium, hydrodynamic interactions slow down both the long-time and the short-time decays of the intermediate scattering function S(q,t), for wavevectors close to the peak of the static structure factor S(q), by a factor of roughly two. The long-time slowing is diminished at high interaction strengths whereas the short-time slowing (quantified via the hydrodynamic factor H(q)) is less affected by the dipolar interactions, despite their strong effect on the pair distribution function arising from cluster formation. Cluster formation is also studied in transient data following a quench from λ = 0; hydrodynamic interactions slow the formation rate, again by a factor of roughly two. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0910/0910.3523v1.pdf"}
{"id": "0912.3161", "abstract": "  An exact analytical theory is developed for calculating the diffusion coefficient of charge carriers in strongly anisotropic disordered solids with one-dimensional hopping transport mode for any dependence of the hopping rates on space and energy. So far such a theory existed only for calculating the carrier mobility. The dependence of the diffusion coefficient on the electric field evidences a linear, non-analytic behavior at low fields for all considered models of disorder. The mobility, on the contrary, demonstrates a parabolic, analytic field dependence for a random-barrier model, being linear, non-analytic for a random energy model. For both models the Einstein relation between the diffusion coefficient and mobility is proven to be violated at any finite electric field. The question on whether these non-analytic field dependences of the transport coefficients and the concomitant violation of the Einstein's formula are due to the dimensionality of space or due to the considered models of disorder is resolved in the following paper [Nenashev et al., arXiv:0912.3169], where analytical calculations and computer simulations are carried out for two- and three-dimensional systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0912/0912.3161v1.pdf"}
{"id": "0912.3831", "abstract": "  Using the Gamma Ray Burst Monitor (GBM) on-board Fermi, we are monitoring the hard X-ray/soft gamma ray sky using the Earth occultation technique. Each time a source in our catalog enters or exits occultation by the Earth, we measure its flux using the change in count rates due to the occultation. Currently we are using CTIME data with 8 energy channels spanning 8 keV to 1 MeV for the GBM NaI detectors and spanning 150 keV to 40 MeV for the GBM BGO detectors. Our preliminary catalog consists of galactic X-ray binaries, the Crab Nebula, and active galactic nuclei. In addition, to Earth occultations, we have observed numerous occultations with Fermi's solar panels. We will present early results. Regularly updated results can be found on our website http://gammaray.nsstc.nasa.gov/gbm/science/occultation ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/0912/0912.3831v1.pdf"}
{"id": "1001.2442", "abstract": "  Generic non-magnetic disorder effects onto those topological quantum critical points (TQCP), which intervene the three-dimensional topological insulator and an ordinary insulator, are investigated. We first show that, in such 3-d TQCP, any backward scattering process mediated by the chemical-potential-type impurity is always canceled by its time-reversal (T-reversal) counter-process, because of the non-trivial Berry phase supported by these two processes in the momentum space. However, this cancellation can be generalized into only those backward scattering processes which conserve a certain internal degree of freedom, i.e. the parity density, while the `absolute' stability of the TQCP against any non-magnetic disorders is required by the bulk-edge correspondence. Motivated by this, we further derive the self-consistent-Born phase diagram in the presence of generic non-magnetic disorder potentials and argue the behaviour of the quantum conductivity correction in such cases. The distinction and similarity between the case with only the chemical-potential-type disorder and that with the generic non-magnetic disorders are finally summarized. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1001/1001.2442v1.pdf"}
{"id": "1005.3374", "abstract": "  We study the performance of common quantum stabilizer codes in the presence of asymmetric and correlated errors. Specifically, we consider the depolarizing noisy quantum memory channel and perform quantum error correction via the five and seven-qubit stabilizer codes. We characterize these codes by means of the entanglement fidelity as function of the error probability and the degree of memory. We show that their performances are lowered by the presence of correlations and we compute the error probability threshold values for codes effectiveness. Furthermore, we uncover that the asymmetry in the error probabilities does not affect the performance of the five-qubit code while it does affect the performance of the seven-qubit code which results less effective when considering correlated and symmetric depolarizing errors but more effective for correlated and asymmetric errors. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1005/1005.3374v1.pdf"}
{"id": "1006.1188", "abstract": "  We study a general problem how the gap in a nonmagnetic band insulator closes by tuning a parameter. We review our recent results on the classification of all the possible gap closing in two and three dimensions. We show that they accompany the change of Z_2 topological numbers, and that the gap closings correspond to phase transitions between the quantum spin Hall and the insulator phases. Interestingly, in inversion-asymmetric three-dimensional systems there appears a gapless phase between the quantum spin Hall and insulator phases. This gapless phase is due to a topological nature of gap-closing points in three dimensions, but not in two dimensions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1006/1006.1188v3.pdf"}
{"id": "1007.2962", "abstract": "  Measurements of strangeness production in jets help illuminate the QCD mechanisms in fragmentation. Furthermore, they provide a crucial baseline for heavy-ion studies where modifications in jet chemistry have recently been predicted. We present new results on strange particle production in jets from p+p √(s) = 200 GeV collisions measured by the STAR experiment. The momentum distributions of the Λ, Λ̅ and K0Short particles are obtained using various jet finding algorithms, and then compared to various models. Strange particle ratios in jets are obtained and compared to values obtained from the inclusive spectra. Finally, we show jets tagged with leading strange baryons and mesons, in order to investigate whether gluon or quark jets can be isolated in this way. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1007/1007.2962v1.pdf"}
{"id": "1007.3915", "abstract": "  Proton hexality is a discrete symmetry that avoids the problem of too fast proton decay in the supersymmetric extension of the standard model. Unfortunately it is inconsistent with conventional grand unification. We show that proton hexality can be incorporated in the scheme of \"Local Grand Unification\" discussed in the framework of model building in (heterotic) string theory. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1007/1007.3915v2.pdf"}
{"id": "1008.4539", "abstract": "  Mechanical shear deformations lead, in some cases, to effects similar to those resulting from ion irradiation. Here we characterize the effects of shear velocity and temperature on amorphous silicon () modelled using classical molecular dynamics simulations based on the empirical Environment Dependent Inter-atomic Potential (EDIP). With increasing shear velocity at low temperature, we find a systematic increase in the internal strain leading to the rapid appearance of structural defects (5-fold coordinated atoms). The impacts of externally applied strain can be almost fully compensated by increasing the temperature, allowing the system to respond more rapidly to the deformation. In particular, we find opposite power-law relations between the temperature and the shear velocity and the deformation energy. The spatial distribution of defects is also found to strongly depend on temperature and strain velocity. For low temperature or high shear velocity, defects are concentrated in a few atomic layers near the center of the cell while, with increasing temperature or decreasing shear velocity, they spread slowly throughout the full simulation cell. This complex behavior can be related to the structure of the energy landscape and the existence of a continuous energy-barrier distribution. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1008/1008.4539v2.pdf"}
{"id": "1008.5078", "abstract": "  It is well known that text compression can be achieved by predicting the next symbol in the stream of text data based on the history seen up to the current symbol. The better the prediction the more skewed the conditional probability distribution of the next symbol and the shorter the codeword that needs to be assigned to represent this next symbol. What about the opposite direction ? suppose we have a black box that can compress text stream. Can it be used to predict the next symbol in the stream ? We introduce a criterion based on the length of the compressed data and use it to predict the next symbol. We examine empirically the prediction error rate and its dependency on some compression parameters. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1008/1008.5078v1.pdf"}
{"id": "1009.1871", "abstract": "  We study the post-main sequence stars in NGC 604, the most luminous HII region in M33. Previously, a number of Wolf-Rayet (WR) stars and one red supergiant (RSG) have been discovered. Based on broadband photometry of the region, we present evidence that is consistent with the presence of this RSG and with three more RSG candidates. Using SED fitting based on HST UVIJHK photometry we estimate the ages of the WR stars and RSGs finding that the two populations are from distinct formation episodes with ages 3.2±", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.1871v1.pdf"}
{"id": "1009.4384", "abstract": "  We exploit the tripartite negativity to study the thermal correlations in a tripartite system, that is the three outer spins interacting with the central one in a spin-star system. We analyze the dependence of such correlations on the homogeneity of the interactions, starting from the case where central-outer spin interactions are identical and then focusing on the case where the three coupling constants are different. We single out some important differences between the negativity and the concurrence. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1009/1009.4384v3.pdf"}
{"id": "1010.2393", "abstract": "  Studies are presented of the selection of events consistent with top quark pair production in data recorded by the CMS detector at the LHC, corresponding to an integrated luminosity of 0.84+/-0.09 1/pb and at center-of-mass energy sqrts=7 TeV. Results are presented for the lepton+jets as well as dilepton channels. Event yields in data are compared to those in simulation, and several background processes are estimated using data-driven techniques. The observed yields of top-antitop candidate events are roughly consistent with the Standard Model. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.2393v1.pdf"}
{"id": "1010.3660", "abstract": "  When galaxy clusters collide, they generate shock fronts in the hot intracluster medium. Observations of these shocks can provide valuable information on the merger dynamics and physical conditions in the cluster plasma, and even help constrain the nature of dark matter. To study shock fronts, one needs an X-ray telescope with high angular resolution (such as Chandra), and be lucky to see the merger from the right angle and at the right moment. As of this writing, only a handful of merger shock fronts have been discovered and confirmed using both X-ray imaging and gas temperature data – those in 1E0657-56, A520, A754, and two fronts in A2146. A few more are probable shocks awaiting temperature profile confirmation – those in A521, RXJ1314-25, A3667, A2744, and Coma. The highest Mach number is 3 in 1E0657-56, while the rest has M=1.6-2. Interestingly, all these relatively weak X-ray shocks coincide with sharp edges in their host cluster's synchrotron radio halos (except in A3667, where it coincides with the distinct radio relic, and A2146, which does not have radio data yet). This is contrary to the common wisdom that weak shocks are inefficient particle accelerators, and may shed light on the mechanisms of relativistic electron production in astrophysical plasmas. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1010/1010.3660v1.pdf"}
{"id": "1011.1245", "abstract": "  We investigate thermal inflation in double-screen entropic cosmology. We find that its realization is general, resulting from the system evolution from non-equilibrium to equilibrium. Furthermore, going beyond the background evolution, we study the primordial curvature perturbations arising from the universe interior, as well as from the thermal fluctuations generated on the holographic screens. We show that the power spectrum is nearly scale-invariant with a red tilt, while the tensor-to-scalar ratio is in agreement with observations. Finally, we examine the non-Gaussianities of primordial curvature perturbations, and we find that a sizable value of the non-linearity parameter is possible due to holographic statistics on the outer screen. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1011/1011.1245v2.pdf"}
{"id": "1012.1672", "abstract": "  We propose an incentive scheme based on intervention to sustain cooperation among self-interested users. In the proposed scheme, an intervention device collects imperfect signals about the actions of the users for a test period, and then chooses the level of intervention that degrades the performance of the network for the remaining time period. We analyze the problems of designing an optimal intervention rule given a test period and choosing an optimal length of the test period. The intervention device can provide the incentive for cooperation by exerting intervention following signals that involve a high likelihood of deviation. Increasing the length of the test period has two counteracting effects on the performance: It improves the quality of signals, but at the same time it weakens the incentive for cooperation due to increased delay. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1012/1012.1672v1.pdf"}
{"id": "1101.3986", "abstract": "  We study the effect of decoherence on a qubit-qutrit system under the influence of global, local and multilocal decoherence in non-inertial frames. We show that the entanglement sudden death can be avoided in non-inertial frames in the presence of amplitude damping, depolarizing and phase damping channels. However, degradation of entanglement is seen due to Unruh effect. It is shown that for lower level of decoherence, the depolarizing channel degrades the entanglement more heavily as compared to the amplitude damping and phase damping channels. However, for higher values of decoherence parameters, amplitude damping channel heavily degrades the entanglement of the hybrid system. Further more, no ESD is seen for any value of Rob's acceleration. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1101/1101.3986v1.pdf"}
{"id": "1101.4858", "abstract": "  We show that the contributions of three-quasiparticle interactions to normal Fermi systems at low energies and temperatures are suppressed by n_q/n compared to two-body interactions, where n_q is the density of excited or added quasiparticles and n is the ground-state density. For finite Fermi systems, three-quasiparticle contributions are suppressed by the corresponding ratio of particle numbers N_q/N. This is illustrated for polarons in strongly interacting spin-polarized Fermi gases and for valence neutrons in neutron-rich calcium isotopes. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1101/1101.4858v1.pdf"}
{"id": "1102.0778", "abstract": "  We model a system of ultracold fermionic dipolar molecules on a two-dimensional square lattice. Assuming that the molecules are in their nondegenerate hyperfine ground state, and that the dipole moment is polarized perpendicular to the plane (as in the recent experiments on 40K-87Rb molecules), we approximate these molecules as spinless fermions with long range repulsive dipolar interactions. We use mean field theory to obtain the restricted phase diagram as a function of the filling, the strength of interaction and the temperature. We find a number of ordered density wave phases in the system, as well as phase separation between these phases. A Monte Carlo analysis shows that the higher-period phases are usually suppressed in the exact solution. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.0778v1.pdf"}
{"id": "1102.2158", "abstract": "  A complete intersection of n polynomials in n indeterminates has only a finite number of zeros. In this paper we address the following question: how do the zeros change when the coefficients of the polynomials are perturbed? In the first part we show how to construct semi-algebraic sets in the parameter space over which all the complete intersection ideals share the same number of isolated real zeros. In the second part we show how to modify the complete intersection and get a new one which generates the same ideal but whose real zeros are more stable with respect to perturbations of the coefficients. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1102/1102.2158v1.pdf"}
{"id": "1103.0745", "abstract": "  The Large Area Telescope (LAT) on board of the Fermi satellite detected emission above 30 MeV only in a small fraction of the long gamma-ray bursts (GRBs) detected by the Fermi Gamma-ray Burst Monitor (GBM) at 8 keV - 10 MeV. Those bursts that were detected by the LAT were among the brightest GBM bursts. We examine a sample of the most luminous GBM bursts with no LAT detection and obtain upper limits on their high energy fluence. We find an average upper limit of LAT/GBM fluence ratio of 0.13 for GeV fluence during T_90 and an average upper limit ratio of 0.45 for GeV fluence during the first 600 seconds after the trigger. These ratios strongly constrain various emission models and in particular rule out SSC models for the prompt emission. In about a third of both LAT detected and LAT non-detected bursts, we find that the extrapolation of the MeV range Band spectrum to the GeV range is larger than the observed GeV fluence (or its upper limit). While this excess is not highly significant for any specific burst, the overall excess in a large fraction of the bursts suggests a decline in the high energy spectral slope in at least some of these bursts. Possibly an evidence for the long sought after pair creation limit. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1103/1103.0745v2.pdf"}
{"id": "1104.0521", "abstract": "  The instabilities of relativistic ion beams in a relativistically hot electron background are derived for general propagation angles. It is shown that the Weibel instability in the direction perpendicular to the streaming direction is the fastest growing mode, and probably the first to appear, consistent with the aligned filaments that are seen in PIC simulations. Oblique, quasiperpendicular modes grow almost as fast, as the growth rate varies only moderately with angle, and they may distort or corrugate the filaments after the perpendicular mode saturates. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1104/1104.0521v1.pdf"}
{"id": "1104.2990", "abstract": "  We study experimentally and numerically the existence and stability properties of discrete breathers in a periodic nonlinear electric line. The electric line is composed of single cell nodes, containing a varactor diode and an inductor, coupled together in a periodic ring configuration through inductors and driven uniformly by a harmonic external voltage source. A simple model for each cell is proposed by using a nonlinear form for the varactor characteristics through the current and capacitance dependence on the voltage. For an electrical line composed of 32 elements, we find the regions, in driver voltage and frequency, where n-peaked breather solutions exist and characterize their stability. The results are compared to experimental measurements with good quantitative agreement. We also examine the spontaneous formation of n-peaked breathers through modulational instability of the homogeneous steady state. The competition between different discrete breathers seeded by the modulational instability eventually leads to stationary n-peaked solutions whose precise locations is seen to sensitively depend on the initial conditions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1104/1104.2990v1.pdf"}
{"id": "1105.4336", "abstract": "  We investigate here the spectrum of gravitational collapse endstates when arbitrarily small perfect fluid pressures are introduced in the classic black hole formation scenario as described by Oppenheimer, Snyder and Datt (OSD) [1]. This extends a previous result on tangential pressures [2] to the more physically realistic scenario of perfect fluid collapse. The existence of classes of pressure perturbations is shown explicitly, which has the property that injecting any smallest pressure changes the final fate of the dynamical collapse from a black hole to a naked singularity. It is therefore seen that any smallest neighborhood of the OSD model, in the space of initial data, contains collapse evolutions that go to a naked singularity outcome. This gives an intriguing insight on the nature of naked singularity formation in gravitational collapse. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1105/1105.4336v2.pdf"}
{"id": "1106.4166", "abstract": "  The first X-class flare of the current solar cycle 24 occurred in Active Region NOAA 11158 during its central meridian passage on 2011 February 15. This two ribbon white-light flare was well observed by the Helioseismic and Magnetic Imager (HMI) on board Solar Dynamics Observatory (SDO). During the peak phase of the flare, we detected magnetic and Doppler velocity transients appearing near the umbral boundary of the main sunspot. These transients persisted for a few minutes and showed spatial and temporal correspondence with the flare kernels. The observed magnetic polarity at the transients' locations underwent sign reversal, together with large enhancement in Doppler velocities. We explain this observational phenomena using the HMI spectral data obtained before, during and after the flare. These changes were reflected in the maps of the AR in all the Stokes parameters. Association of the transient features with various signatures of the flare and the cause and effects of their appearance are also presented on the basis of present theoretical models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1106/1106.4166v3.pdf"}
{"id": "1107.1009", "abstract": "  We report on the generation of high-order optical vortices by spiral phase mirrors. The phase mirrors are produced by direct machining with a diamond tool and are shown to produce high-quality optical vortices with topological charges ranging from 1 to 1000 at a wavelength of 532 nm. The direct machining technique is flexible and offers the promise of high-precision, large-diameter spiral phase mirrors that are compatible with high optical powers. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.1009v1.pdf"}
{"id": "1107.2805", "abstract": "  The distribution of capture zones formed during the nucleation and growth of point islands on a one-dimensional substrate during monomer deposition is considered for general critical island size i. A fragmentation theory approach yields the small and (for i=0) large size asymptotics for the capture zone distribution (CZD) under the assumption of no neighbour-neighbour gap size correlation. These CZD asymptotic forms are different to those of the Generalised Wigner Surmise which has recently been proposed for island nucleation and growth models, and we discuss the reasons for the discrepancies. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.2805v3.pdf"}
{"id": "1107.5159", "abstract": "  The weak equivalence principle of gravity is examined at the quantum level in two ways. First, the position detection probabilities of particles described by a non-Gaussian wave-packet projected upwards against gravity around the classical turning point and also around the point of initial projection are calculated. These probabilities exhibit mass-dependence at both these points, thereby reflecting the quantum violation of the weak equivalence principle. Secondly, the mean arrival time of freely falling particles is calculated using the quantum probability current, which also turns out to be mass dependent. Such a mass-dependence is shown to be enhanced by increasing the non-Gaussianity parameter of the wave packet, thus signifying a stronger violation of the weak equivalence principle through a greater departure from Gaussianity of the initial wave packet. The mass-dependence of both the position detection probabilities and the mean arrival time vanish in the limit of large mass. Thus, compatibility between the weak equivalence principle and quantum mechanics is recovered in the macroscopic limit of the latter. A selection of Bohm trajectories is exhibited to illustrate these features in the free fall case. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1107/1107.5159v2.pdf"}
{"id": "1108.1137", "abstract": "  Bottomonium S-wave states were studied using lattice NRQCD. Masses of ground and excited states were calculated using multiexponential fitting to a set of correlation functions constructed using both local and wavefunction-smeared operators. Three-point functions for M1 transitions between vector and pseudoscalar states were computed. Robust signals for transitions involving the first two excited states were obtained. The qualitative features of the transition matrix elements are in agreement with expectations. The calculated values of matrix elements for Y(2S) and Y(3S) decay are considerably larger than values inferred from measured decay widths. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1108/1108.1137v2.pdf"}
{"id": "1110.1201", "abstract": "  We describe the implementation of the PhotoZ code in the framework of the Astro-WISE package and as part of the Photometric Classification Server of the PanSTARRS pipeline. Both systems allow the automatic measurement of photometric redshifts for the millions of objects being observed in the PanSTARRS project or expected to be observed by future surveys like KIDS, DES or EUCLID. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.1201v2.pdf"}
{"id": "1110.4755", "abstract": "  Dynamical systems driven by a general Lévy stable noise are considered. The inertia is included and the noise, represented by a generalised Ornstein-Uhlenbeck process, has a finite relaxation time. A general linear problem (the additive noise) is solved: the resulting distribution converges with time to the distribution for the white-noise, massless case. Moreover, a multiplicative noise is discussed. It can make the distribution steeper and the variance, which is finite, depends sublinearly on time (subdiffusion). For a small mass, a white-noise limit corresponds to the Stratonovich interpretation. On the other hand, the distribution tails agree with the Ito interpretation if the inertia is very large. An escape time from the potential well is calculated. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1110/1110.4755v2.pdf"}
{"id": "1111.3949", "abstract": "  We study the two-dimensional Kane-Mele-Hubbard model at half filling by means of quantum Monte Carlo simulations. We present a refined phase boundary for the quantum spin liquid. The topological insulator at finite Hubbard interaction strength is adiabatically connected to the groundstate of the Kane-Mele model. In the presence of spin-orbit coupling, magnetic order at large Hubbard U is restricted to the transverse direction. The transition from the topological band insulator to the antiferromagnetic Mott insulator is in the universality class of the three-dimensional XY model. The numerical data suggest that the spin liquid to topological insulator and spin liquid to Mott insulator transitions are both continuous. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.3949v2.pdf"}
{"id": "1111.5202", "abstract": "  We present SDO/AIA observations of the interaction of a global EUV wave on 2011 June 7 with active regions (ARs), coronal holes (CHs) and coronal bright structures. The primary global wave has a three-dimensional dome shape, with propagation speeds ranging from 430-780 km/s in different directions. The primary coronal wave runs in front of the expanding loops involved in the CME and its propagation speeds are approximately constant within 10-20 minutes. Upon arrival at an AR on its path, the primary EUV wave apparently disappears and a secondary wave rapidly reemerges 75 Mm within the AR boundary at a similar speed. When the EUV wave encounters a coronal bright structure, an additional wave front appears there and propagates in front of it at a velocity nearly a factor of 2 faster. Reflected waves from a polar CH and a coronal bright structure are observed and propagate fractionally slower than the primary waves. Some of these phenomena can be equally explained by either a wave or non-wave model alone. However, taken together, these observations provide new evidence for the multitudes of global EUV waves, in which a true MHD fast-mode wave or shock propagates in front of an expanding CME bubble. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1111/1111.5202v1.pdf"}
{"id": "1112.0233", "abstract": "  We analyze income tax evasion dynamics in a standard model of statistical mechanics, the Ising model of ferromagnetism. However, in contrast to previous research, we use an inhomogeneous multi-dimensional Ising model where the local degrees of freedom (agents) are subject to a specific social temperature and coupled to external fields which govern their social behavior. This new modeling frame allows for analyzing large societies of four different and interacting agent types. As a second novelty, our model may reproduce results from agent-based models that incorporate standard Allingham and Sandmo tax evasion features as well as results from existing two-dimensional Ising based tax evasion models. We then use our model for analyzing income tax evasion dynamics under different enforcement scenarios and point to some policy implications. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.0233v1.pdf"}
{"id": "1112.0628", "abstract": "  Atomic physics and hadron physics are both based on Yang Mills gauge theory; in fact, quantum electrodynamics can be regarded as the zero-color limit of quantum chromodynamics. I review a number of areas where the techniques of atomic physics provide important insight into the theory of hadrons in QCD. For example, the Dirac-Coulomb equation, which predicts the spectroscopy and structure of hydrogenic atoms, has an analog in hadron physics in the form of light-front relativistic equations of motion which give a remarkable first approximation to the spectroscopy, dynamics, and structure of light hadrons. The renormalization scale for the running coupling, which is unambiguously set in QED, leads to a method for setting the renormalization scale in QCD. The production of atoms in flight provides a method for computing the formation of hadrons at the amplitude level. Conversely, many techniques which have been developed for hadron physics, such as scaling laws, evolution equations, and light-front quantization have equal utility for atomic physics, especially in the relativistic domain. I also present a new perspective for understanding the contributions to the cosmological constant from QED and QCD. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1112/1112.0628v2.pdf"}
{"id": "1201.0920", "abstract": "  We analyzed multimode Josephson junctions with exciton-polaritons (polaritonic Josephson junctions) when several coupling mechanisms of fundamental and excited states are present. The applied method is based on Keldysh-Green function formalism and takes into account polariton pseudospin. We found that mean value of circular polarization degree in intrinsic Josephson oscillations and microscopic quantum self-trapping follow an oscillator behavior whose renormalizes due to intermode interactions. The effect of an additional transfer of particles over junction barrier occurring in multimode approximation in combination with common Josephson tunneling is discussed in regime of dynamical separation of two polarizations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1201/1201.0920v1.pdf"}
{"id": "1201.2831", "abstract": "  We study an Andreev quantum dot, that is a quantum dot inserted in a superconducting ring, with several levels or conducting channels. We analyze the degeneracy of the ground state as a function of the phase difference and of the gate voltage and find its dependence on the Coulomb interaction within and between channels. We compute a (non integer) charge of the dot region and Josephson current. The charge-to-phase and current-to-gate voltage sensitivities are studied. We find that, even in the presence of Coulomb interaction between the channels, the sensitivity increases with the number of channels, although it does not scale linearly as in the case with no interactions. The Andreev quantum dot may therefore be used as a sensitive detector of magnetic flux or as a Josephson transistor. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1201/1201.2831v3.pdf"}
{"id": "1202.1853", "abstract": "  We study the classic Susceptible-Infected-Recovered (SIR) model for the spread of an infectious disease. In this stochastic process, there are two competing mechanism: infection and recovery. Susceptible individuals may contract the disease from infected individuals, while infected ones recover from the disease at a constant rate and are never infected again. Our focus is the behavior at the epidemic threshold where the rates of the infection and recovery processes balance. In the infinite population limit, we establish analytically scaling rules for the time-dependent distribution functions that characterize the sizes of the infected and the recovered sub-populations. Using heuristic arguments, we also obtain scaling laws for the size and duration of the epidemic outbreaks as a function of the total population. We perform numerical simulations to verify the scaling predictions and discuss the consequences of these scaling laws for near-threshold epidemic outbreaks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.1853v1.pdf"}
{"id": "1202.1900", "abstract": "  We study the propagation of light in a resonator optical waveguide consisting of evanescently coupled optomechanical crystal array. In the strong driving limit, the Hamiltonian of system can be linearized and diagonalized. In this case we obtain the polaritons, which is formed by the interaction of photons and the collective excitation of mechanical resonators. By analyzing the dispersion relations of polaritons, we find that the band structure can be controlled by changing the related parameters. It has been suggested an engineerable band structure can be used to slow and stop light pulses. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.1900v1.pdf"}
{"id": "1202.3855", "abstract": "  By considering a counting-type argument on Brownian sample paths, we prove a result similar to that of Orey and Taylor on the exact Hausdorff dimension of the rapid points of Brownian motion. Because of the nature of the proof we can then apply the concepts to so-called complex oscillations (or 'algorithmically random Brownian motion'), showing that their rapid points have the same dimension. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1202/1202.3855v2.pdf"}
{"id": "1203.1008", "abstract": "  R-modes can generate strong magnetic fields in the core of accreting millisecond neutron stars (NSs). The diffusion of these fields outside the core causes the growth of the external magnetic field and thus it affects the evolution of the spin down rates Ṗ of the millisecond pulsars (MSPs). The diffusion of the internal magnetic field provides a new evolutionary path for the MSPs. This scenario could explain the large Ṗ of the pulsars J1823-3021A and J1824-2452A. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1203/1203.1008v3.pdf"}
{"id": "1204.4682", "abstract": "  We theoretically analyze the Bragg spectroscopic interferometer of two spatially separated atomic Bose-Einstein condensates that was experimentally realized by Saba et al. [Science 2005 v307 p1945] by continuously monitoring the relative phase evolution. Even though the atoms in the light-stimulated Bragg scattering interact with intense coherent laser beams, we show that the phase is created by quantum measurement-induced back-action on the homodyne photo-current of the lasers, opening possibilities for quantum-enhanced interferometric schemes. We identify two regimes of phase evolution: a running phase regime which was observed in the experiment of Saba et al., that is sensitive to an energy offset and suitable for an interferometer, and a trapped phase regime, that can be insensitive to applied forces and detrimental to interferometric applications. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1204/1204.4682v2.pdf"}
{"id": "1206.2483", "abstract": "  Although devices working on quantum principles can revolutionize the electronic industry, they have not been achieved yet as it is difficult to control their stability. We show that one can use evanescent modes to build stable quantum switches. The physical principles that make this possible is explained in detail. Demonstrations are given using a multichannel Aharonov - Bohm interferometer. We propose a new S matrix for multichannel junctions to solve the scattering problem. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1206/1206.2483v2.pdf"}
{"id": "1207.3837", "abstract": "  The massive amounts of data that social media generates has facilitated the study of online human behavior on a scale unimaginable a few years ago. At the same time, the much discussed apparent randomness with which people interact online makes it appear as if these studies cannot reveal predictive social behaviors that could be used for developing better platforms and services. We use two large social databases to measure the mutual information entropy that both individual and group actions generate as they evolve over time. We show that user's interaction sequences have strong deterministic components, in contrast with existing assumptions and models. In addition, we show that individual interactions are more predictable when users act on their own rather than when attending group activities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1207/1207.3837v2.pdf"}
{"id": "1208.3551", "abstract": "  We study the distinction and quantification of chaotic and regular motion in a time-dependent Hamiltonian barred galaxy model. Recently, a strong correlation was found between the strength of the bar and the presence of chaotic motion in this system, as models with relatively strong bars were shown to exhibit stronger chaotic behavior compared to those having a weaker bar component. Here, we attempt to further explore this connection by studying the interplay between chaotic and regular behavior of star orbits when the parameters of the model evolve in time. This happens for example when one introduces linear time dependence in the mass parameters of the model to mimic, in some general sense, the effect of self-consistent interactions of the actual N-body problem. We thus observe, in this simple time-dependent model also, that the increase of the bar's mass leads to an increase of the system's chaoticity. We propose a new way of using the Generalized Alignment Index (GALI) method as a reliable criterion to estimate the relative fraction of chaotic vs. regular orbits in such time-dependent potentials, which proves to be much more efficient than the computation of Lyapunov exponents. In particular, GALI is able to capture subtle changes in the nature of an orbit (or ensemble of orbits) even for relatively small time intervals, which makes it ideal for detecting dynamical transitions in time-dependent systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1208/1208.3551v3.pdf"}
{"id": "1208.3985", "abstract": "  By considering level shifting during the insertion process we revisit the quantum Szilard engine (QSZE) with fully quantum consideration. We derive the general expressions of the heat absorbed from thermal bath and the total work done to the environment by the system in a cycle with two different cyclic strategies. We find that only the quantum information contributes to the absorbed heat, and the classical information acts like a feedback controller and has no direct effect on the absorbed heat. This is the first demonstration of the different effects of quantum information and classical information for extracting heat from the bath in the QSZE. Moreover, when the well width L→∞ or the temperature of the bath T→∞ the QSZE reduces to the classical Szilard engine (CSZE), and the total work satisfies the relation W_𝚝𝚘𝚝=k_BT 𝚕𝚗2 as obtained by Sang Wook Kim et al. [Phys. Rev. Lett. 106, 070401 (2011)] for one particle case. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1208/1208.3985v2.pdf"}
{"id": "1209.4920", "abstract": "  We present a new, approximate method for modelling the acceleration and collimation of relativistic jets in the presence of gravity. This method is self-similar throughout the computational domain where gravitational effects are negligible and, where significant, self-similar within a flux tube. These solutions are applicable to jets launched from a small region (e.g., near the inner edge of an accretion disk). As implied by earlier work, the flow can converge onto the rotation axis, potentially creating a collimation shock.   In this first version of the method, we derive the gravitational contribution to the relativistic equations by analogy with non-relativistic flow. This approach captures the relativistic kinetic gravitational mass of the flowing plasma, but not that due to internal thermal and magnetic energies. A more sophisticated treatment, derived from the basic general relativistic magnetohydrodynamical equations, is currently being developed.   Here we present an initial exploration of parameter space, describing the effects the model parameters have on flow solutions and the location of the collimation shock. These results provide the groundwork for new, semi-analytic models of relativistic jets which can constrain conditions near the black hole by fitting the jet break seen increasingly in X-ray binaries. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1209/1209.4920v1.pdf"}
{"id": "1210.0483", "abstract": "  In general relativity, astrophysical black holes are uniquely described by the Kerr metric. Observational tests of the Kerr nature of these compact objects and, hence, of general relativity, require a metric that encompasses a broader class of black holes as possible alternatives to the usual Kerr black holes. Several such Kerr-like metrics have been constructed to date, which depend on a set of free parameters and which reduce smoothly to the Kerr metric if all deviations vanish. Many of these metrics, however, are valid only for small values of the spin or small perturbations of the Kerr metric or contain regions of space where they are unphysical hampering their ability to properly model the accretions flows of black holes. In this paper, I describe a Kerr-like black hole metric that is regular everywhere outside of the event horizon for black holes with arbitrary spins even for large deviations from the Kerr metric. This metric, therefore, provides an ideal framework for tests of the nature of black holes with observations of the emission from their accretion flows, and I give several examples of such tests across the electromagnetic spectrum with current and near-future instruments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.0483v1.pdf"}
{"id": "1210.6850", "abstract": "  From a sample of GRBs detected by the Fermi and Swift missions, we have extracted the minimum variability time scales for temporal structures in the light curves associated with the prompt emission and X-ray flares. A comparison of this variability time scale with pulse parameters such as rise times,determined via pulse-fitting procedures, and spectral lags, extracted via the cross-correlation function (CCF), indicate a tight correlation between these temporal features for both the X-ray flares and the prompt emission. These correlations suggests a common origin for the production of X-ray flares and the prompt emission in GRBs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1210/1210.6850v2.pdf"}
{"id": "1211.5306", "abstract": "  Virtual Institute of Astroparticle Physics (VIA), integrated in the structure of Laboratory of AstroParticle physics and Cosmology (APC) is evolved in a unique multi-functional complex of e-science and e-learning, supporting at distance interactive online participation in conferences and meetings, various forms of collaborative scientific work as well as programs of education. The activity of VIA takes place on its website and includes regular videoconferences with systematic basic courses and lectures on various issues of astroparticle physics, regular online transmission of APC Colloquiums, participation at distance in various scientific meetings and conferences, library of their records and presentations, a multilingual Forum. VIA virtual rooms are open for meetings of scientific groups and for individual work of supervisors with their students. The format of a VIA videoconferences was effectively used in the program of XV Bled Workshop to provide a world-wide participation at distance in discussion of the open questions of physics beyond the standard model. The VIA system has demonstrated its high quality and stability even for minimal equipment (laptop with microphone and webcam and WiFi Internet connection) and without any technical assistance at place. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1211/1211.5306v1.pdf"}
{"id": "1301.0657", "abstract": "  We report on observations of the γ-ray and optical photopolarimetric behavior of the radio-loud, narrow line type-1 Seyfert galaxy PMN J0948+0022 over a twenty seven month period. As this object has recently been suggested to represent a prototype of an emerging class of blazar-like objects, the observed properties are compared to those of blazars. We extract doubling timescales of roughly 4 hours for the optical and γ-ray bands. The rapid microvariability in the optical/NIR, significant and variable optical polarization, and strong yet rapidly-variable γ-ray emission we observe for PMN J0948+0022 are all classical observational characteristics associated with blazars. However, since these observations do not show a clear correlation between the γ-ray and optical behavior, they do not offer conclusive proof that the emissive behavior of PMN J0948+0022 is due to a relativistic jet oriented close to our line of sight. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1301/1301.0657v2.pdf"}
{"id": "1302.2550", "abstract": "  We derive sublinear regret bounds for undiscounted reinforcement learning in continuous state space. The proposed algorithm combines state aggregation with the use of upper confidence bounds for implementing optimism in the face of uncertainty. Beside the existence of an optimal policy which satisfies the Poisson equation, the only assumptions made are Holder continuity of rewards and transition probabilities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1302/1302.2550v1.pdf"}
{"id": "1303.2133", "abstract": "  Weather forecasting is mostly based on the outputs of deterministic numerical weather forecasting models. Multiple runs of these models with different initial conditions result in forecast ensembles which is are used for estimating the distribution of future atmospheric variables. However, these ensembles are usually under-dispersive and uncalibrated, so post-processing is required.   In the present work Bayesian Model Averaging (BMA) is applied for calibrating ensembles of temperature forecasts produced by the operational Limited Area Model Ensemble Prediction System of the Hungarian Meteorological Service (HMS).   We describe two possible BMA models for temperature data of the HMS and show that BMA post-processing significantly improves calibration and probabilistic forecasts although the accuracy of point forecasts is rather unchanged. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1303/1303.2133v1.pdf"}
{"id": "1303.5251", "abstract": "  In this work we present a flexible tool for tumor progression, which simulates the evolutionary dynamics of cancer. Tumor progression implements a multi-type branching process where the key parameters are the fitness landscape, the mutation rate, and the average time of cell division. The fitness of a cancer cell depends on the mutations it has accumulated. The input to our tool could be any fitness landscape, mutation rate, and cell division time, and the tool produces the growth dynamics and all relevant statistics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1303/1303.5251v1.pdf"}
{"id": "1304.0283", "abstract": "  Remote state preparation (RSP) is a quantum information protocol which allows preparing a quantum state at a distant location with the help of a preshared nonclassical resource state and a classical channel. The efficiency of successfully doing this task can be represented by the RSP-fidelity of the resource state. In this paper, we study the influence on the RSP-fidelity by applying certain local operations on the resource state. We prove that RSP-fidelity does not increase for any unital local operation. However, for nonunital local operation, such as local amplitude damping channel, we find that some resource states can be enhanced to increase the RSP-fidelity. We give the optimal parameter of symmetric local amplitude damping channel for enhancing Bell-diagonal resource states. In addition, we show RSP-fidelity can suddenly change or even vanish at instant under local decoherence. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.0283v1.pdf"}
{"id": "1304.0525", "abstract": "  We investigate the unpolarized pion and kaon fragmentation functions using the nonlocal chiral-quark model. In this model the interactions between the quarks and pseudoscalar mesons is manifested nonlocally. In addition, the explicit flavor SU(3) symmetry breaking effect is taken into account in terms of the current quark masses. The results of our model are evaluated to higher Q^2 value Q^2=4 GeV^2 by the DGLAP evolution. Then we compare them with the empirical parametrizations. We find that our results are in relatively good agreement with the empirical parametrizations and the other theoretical estimations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.0525v1.pdf"}
{"id": "1304.0824", "abstract": "  We study the azimuthal distribution of globular clusters (GCs) in early-type galaxies and compare them to their host galaxies using data from the ACS Virgo Cluster Survey. We find that in host galaxies with visible elongation (epsilon > 0.2) and intermediate to high luminosities (M_z<-19), the GCs are preferentially aligned along the major axis of the stellar light. The red (metal-rich) GC subpopulations show strong alignment with the major axis of the host galaxy, which supports the notion that these GCs are associated with metal-rich field stars. The metal-rich GCs in lenticular galaxies show signs of being more strongly associated with disks rather than bulges. Surprisingly, we find that the blue (metal-poor) GCs can also show the same correlation. If the metal-poor GCs are part of the early formation of the halo and built up through mergers, then our results support a picture where halo formation and merging occur anisotropically, and where the present day major axis is an indicator of the preferred merging axis. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.0824v1.pdf"}
{"id": "1304.2049", "abstract": "  Simple application of the Einstein model combined with the elastic description of solid state is developed. The frequency of quantum oscillators has been assumed as volume dependent and, furthermore, elastic energy terms of static character have been included to complete the description. Such an extension enables to construct the complete thermodynamics. In particular, the model yields practical equation of state and describes the thermal expansion coefficient as well as the isothermal compressibility of solids. The thermodynamic properties resulting from the Gibbs free-energy analysis have been calculated and illustrated in figures. Some comparison of the theoretical results with experimental data for solid argon has been made. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.2049v1.pdf"}
{"id": "1304.5614", "abstract": "  We search for ultra-high energy photons by analyzing geometrical properties of shower fronts of events registered by the Telescope Array surface detector. By making use of an event-by-event statistical method, we derive upper limits on the absolute flux of primary photons with energies above 10^19, 10^19.5 and 10^20 eV based on the first three years of data taken. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.5614v2.pdf"}
{"id": "1304.5968", "abstract": "  Off-diagonal disorder with random hopping between the sublattices of a bipartite lattice is described by a Hamiltonian which has chiral (sub-lattice) symmetry. The energy spectrum is symmetric around E=0 and for odd total number of lattice sites an isolated zero mode always exists, which coincides with the mobility edge of an Anderson transition in two dimensions(2D). In the chiral orthogonal symmetry class BDI we compute the fractal dimension D_2 of the zero mode for graphene samples with edges. In the absence of disorder D_2=1, which corresponds to a one-dimensional edge states, while for strong disorder D_2 decays towards 0 and the zero mode becomes localized. The similarities and differences between zero modes in the honeycomb and the square bipartite lattices are pointed out. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1304/1304.5968v1.pdf"}
{"id": "1305.0769", "abstract": "  Classical novae produce radioactive nuclei which are emitters of gamma-rays in the MeV range. Some examples are the lines at 478 and 1275 keV (from 7Be and 22Na) and the positron-electron annihilation emission, with the 511 keV line and a continuum. Gamma-ray spectra and light curves are potential unique tools to trace the corresponding isotopes and to give insights on the properties of the expanding envelope. Another possible origin of gamma-rays is the acceleration of particles up to very high energies, so that either neutral pions or inverse Compton processes produce gamma-rays of energies larger than 100 MeV. MeV photons during nova explosions have not been detected yet, although several attempts have been made in the last decades; on the other hand, GeV photons from novae have been detected with the Fermi satellite in V407 Cyg, a nova in a symbiotic binary, where the companion is a red giant with a wind, instead of a main sequence star as in the cataclysmic variables hosting classical novae. Two more novae have been detected recently (summer 2012) by Fermi, apparently in non symbiotic binaries, thus challenging our understanding of the emission mechanism. Both scenarios (radioactivities and acceleration) of gamma-ray production in novae are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.0769v1.pdf"}
{"id": "1305.3371", "abstract": "  We conducted the first multi-frequency polarimetric imaging of four broad absorption line (BAL) quasars using Very Long Baseline Array at milli-arcsecond resolutions to investigate the inclination of the non-thermal jet and test the hypothesis that radio sources in BAL quasars are still young. Among these four sources, J0928+446, J1018+0530, and J1405+4056 show one-sided structures in parsec scales, and polarized emission detected in the core. These characteristics are consistent with those of blazars. We set constraints on viewing angles to <66 deg for these jets, in the framework of a Doppler beaming effect. J1159+0112 exhibits an unpolarized gigahertz peaked spectrum component and several discrete blobs with steep spectra on both sides of the central component across ∼1 kpc. These properties are consistent with those of young radio sources. We discuss the structures of jets and AGN wind. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.3371v1.pdf"}
{"id": "1305.5155", "abstract": "  We calculate an analytical expression for the terrace-width distribution P(s) for an interacting step system with nearest and next nearest neighbor interactions. Our model is derived by mapping the step system onto a statistically equivalent 1D system of classical particles. The validity of the model is tested with several numerical simulations and experimental results. We explore the effect of the range of interactions q on the functional form of the terrace-width distribution and pair correlation functions. For physically plausible interactions, we find modest changes when next-nearest neighbor interactions are included and generally negligible changes when more distant interactions are allowed. We discuss methods for extracting from simulated experimental data the characteristic scale-setting terms in assumed potential forms. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1305/1305.5155v1.pdf"}
{"id": "1307.2153", "abstract": "  Magnetic fields are observed on nearly all scales in the universe, from stars and galaxies upto galaxy clusters and even beyond. The origin of cosmic magnetic fields is still an open question, however a large class of models puts its origin in the very early universe. A magnetic dynamo amplifying an initial seed magnetic field could explain the present day strength of the galactic magnetic field. However, it is still an open problem how and when this initial magnetic field was created. Observations of the cosmic microwave background (CMB) provide a window to the early universe and might therefore be able to tell us whether cosmic magnetic fields are of primordial, cosmological origin and at the same time constrain its parameters. We will give an overview of the observational evidence of large scale magnetic fields, describe generation mechanisms of primordial magnetic fields and possible imprints in the CMB. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.2153v1.pdf"}
{"id": "1307.7269", "abstract": "  Antivortex birth, growth and death due to the propagation of a transverse domain wall (DW) in magnetic nanostrips are observed and analyzed. Antivortex formation is an intrinsic process of a strawberry-like transverse DW originated from magnetostatic interaction. Under an external magnetic field, DW in a wider width region tends to move faster than that of a narrower part. This speed mismatch tilts and elongates DW centre line. An antivortex is periodically born near the tail of the DW centre line. The antivortex either moves along the centre line and dies on the other side of the strip, or grows to its maximum size, detaches itself from the DW, and vanishes eventually. The former route reverses the polarity of DW while the later keeps the DW polarity unchanged. The evolution of the DW structures is analyzed using winding numbers assigned to each topological defects. The phase diagram in the field-width plane is obtained and discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1307/1307.7269v2.pdf"}
{"id": "1308.1896", "abstract": "  In this paper we study dynamical compactification in Einstein-Gauss-Bonnet gravity from arbitrary dimension for generic values of the coupling constants. We showed that, when the curvature of the extra dimensional space is negative, for any value of the spatial curvature of the four dimensional space-time one obtains a realistic behavior in which for asymptotic time both the volume of the extra dimension and expansion rate of the four dimensional space-time tend to a constant. Remarkably, this scenario appears within the open region of parameters space for which the theory does not admit any maximally symmetric (4+D)- dimensional solution, which gives to the dynamical compactification an interpretation as geometric frustration. In particular there is no need to fine-tune the coupling constants of the theory so that the present scenario does not violate \"naturalness hypothesis\". Moreover we showed that with increase of the number of extra dimensions the stability properties of the solution are increased. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.1896v2.pdf"}
{"id": "1308.5420", "abstract": "  Dissections of a square into smaller squares, with the smaller squares having relatively prime sizes, are known as Mrs Perkins's quilts. A representation of these dissections using graphs is presented. The edges are directed and coloured North-South or West-East, and the graph corresponds naturally to the dissection. This representation allowed the exhaustive generation of all dissections up to order 18, using the plantri software. The results were cross-checked by generating all dissections of small sizes using a direct approach. The results confirm, extend and introduce several integer sequences. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1308/1308.5420v2.pdf"}
{"id": "1309.0341", "abstract": "  \"Light Shining Through the Wall\" experiments can probe the existence of \"axion like particles\" through their weak coupling to photons. We have adapted such an experiment to the microwave regime and constructed the table top apparatus. This work presents an overview of the experimental setup and then focuses on our latest measurement run and its results. By operating the apparatus within a superconducting MRI magnet, competitive exclusion limits for axion like particles to the first generation optical light shining through the wall experiments have been achieved. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1309/1309.0341v1.pdf"}
{"id": "1310.0766", "abstract": "  We study the electronic properties of rippled freestanding graphene membranes under central load from a sharp tip. To that end, we develop a gauge field theory on a honeycomb lattice valid beyond the continuum theory. Based on the proper phase conjugation of the tight-binding pseudospin Hamiltonian, we develop a method to determine conditions under which continuum elasticity can be used to extract gauge fields from strain. Along the way, we resolve a recent controversy on the theory of strain engineering in graphene: There are no K-point dependent gauge fields. We combine this lattice gauge field theory with atomistic calculations and find that for moderate load, the rippled graphene membranes conform to the extruding tip without significant increase of elastic energy. Mechanical strain is created on a membrane only after a certain amount of load is exerted. In addition, we find that the deformation potential –even when partially screened– induces qualitative changes on the electronic spectra, with Landau levels giving way to equally-spaced peaks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.0766v1.pdf"}
{"id": "1310.4384", "abstract": "  We investigate the correspondence between a non-equilibrium ensemble defined via the distribution of phase-space paths of a Hamiltonian system, and a system driven into a steady-state by non-equilibrium boundary conditions. To discover whether the non-equilibrium path ensemble adequately describes the physics of a driven system, we measure transition rates in a simple one-dimensional model of rotors with Newtonian dynamics and purely conservative interactions. We compare those rates with known properties of the non-equilibrium path ensemble. In doing so, we establish effective protocols for the analysis of transition rates in non-equilibrium quasi-steady states. Transition rates between potential wells and also between phase-space elements are studied, and found to exhibit distinct properties, the more coarse-grained potential wells being effectively further from equilibrium. In all cases the results from the boundary-driven system are close to the path-ensemble predictions, but the question of equivalence of the two remains open. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.4384v2.pdf"}
{"id": "1310.4466", "abstract": "  At first blush, what appears to be a purely physical question to measure any velocity: how to measure the velocity on a one-way trip? However, due to the debates of the clock-synchronization and the successes of Special Relativity (SR), searching of the possibility of one-way speed of light measurement did not receive wider attention since the declaration of the constancy of the speed of light in vacuum by Maxwell's Electrodynamics in 1864. However, our analysis suggests that the debates of the clock synchronization are insignificant when one uses a one-way experiment to test the isotropy of the speed of light - the fundamental postulate of SR. Searching of the possibility of one-way speed of light to test SR is introduced by reviewing recent one-way tests. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.4466v1.pdf"}
{"id": "1310.5259", "abstract": "  We study the irreversible growth of magnetic thin films under the influence of spatially periodic fields by means of extensive Monte Carlo simulations. We find first-order pseudo-phase transitions that separate a dynamically disordered phase from a dynamically ordered phase. By analogy with time-dependent oscillating fields applied to Ising-type models, we qualitatively associate this dynamic transition with the localization/delocalization transition of \"spatial hysteresis\" loops. Depending on the relative width of the magnetic film, L, compared to the wavelength of the external field, λ, different transition regimes are observed. For small systems (L<λ), the transition is associated with the Standard Stochastic Resonance regime, while, for large systems (L>λ), the transition is driven by Anomalous Stochastic Resonance. The origin of the latter is identified as due to the emergence of an additional relevant lengthscale, namely the roughness of the spin domain switching interface. The distinction between different stochastic resonance regimes is discussed at length, both qualitatively by means of snapshot configurations, as well as quantitatively via residence-length and order-parameter probability distributions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.5259v1.pdf"}
{"id": "1310.6939", "abstract": "  Long suspected to be due to unstable accretion events, the type II bursts exhibited by the Rapid Burster (RB, or MXB 1730-335) still lack an exhaustive explanation. Apart from type II bursts, the transient RB also shows the better-understood thermonuclear shell flashes known as type I bursts. In search of links between these two phenomena, we carried out a comprehensive analysis of all Rossi X-ray Timing Explorer observations of the RB and found six atypical type I bursts, featuring a double-peaked profile that is not due to photospheric radius expansion. The bursts appear in a phase of the outburst decay close to the onset of the type II bursts, when the source also switches from the high/soft to the low/hard state. We also report the discovery of a simultaneous low-frequency quasi-periodic oscillation present in the persistent emission as well as in the burst decaying emission. We discuss several scenarios to understand the nature of the peculiar bursts and of the accompanying oscillation, as well as their possible relation with each other and with the type II burst phenomenon. We favour a model consisting of two accretion channels, one polar and one equatorial, in a source viewed at low inclination. We also, for the first time, clearly identify the atoll nature of the RB. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1310/1310.6939v1.pdf"}
{"id": "1311.1626", "abstract": "  As techniques for graph query processing mature, the need for optimization is increasingly becoming an imperative. Indices are one of the key ingredients toward efficient query processing strategies via cost-based optimization. Due to the apparent absence of a common representation model, it is difficult to make a focused effort toward developing access structures, metrics to evaluate query costs, and choose alternatives. In this context, recent interests in covering-based graph matching appears to be a promising direction of research. In this paper, our goal is to formally introduce a new graph representation model, called Minimum Hub Cover, and demonstrate that this representation offers interesting strategic advantages, facilitates construction of candidate graphs from graph fragments, and helps leverage indices in novel ways for query optimization. However, similar to other covering problems, minimum hub cover is NP-hard, and thus is a natural candidate for optimization. We claim that computing the minimum hub cover leads to substantial cost reduction for graph query processing. We present a computational characterization of minimum hub cover based on integer programming to substantiate our claim and investigate its computational cost on various graph types. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1311/1311.1626v2.pdf"}
{"id": "1312.4353", "abstract": "  A distinctive property of human and animal intelligence is the ability to form abstractions by neglecting irrelevant information which allows to separate structure from noise. From an information theoretic point of view abstractions are desirable because they allow for very efficient information processing. In artificial systems abstractions are often implemented through computationally costly formations of groups or clusters. In this work we establish the relation between the free-energy framework for decision making and rate-distortion theory and demonstrate how the application of rate-distortion for decision-making leads to the emergence of abstractions. We argue that abstractions are induced due to a limit in information processing capacity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.4353v2.pdf"}
{"id": "1312.5673", "abstract": "  Flower pollination is an intriguing process in the natural world. Its evolutionary characteristics can be used to design new optimization algorithms. In this paper, we propose a new algorithm, namely, flower pollination algorithm, inspired by the pollination process of flowers. We first use ten test functions to validate the new algorithm, and compare its performance with genetic algorithms and particle swarm optimization. Our simulation results show the flower algorithm is more efficient than both GA and PSO. We also use the flower algorithm to solve a nonlinear design benchmark, which shows the convergence rate is almost exponential. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1312/1312.5673v1.pdf"}
{"id": "1401.7553", "abstract": "  Solid fuel ignition models, for which the dynamics of the temperature is independent of the single-species mass fraction, attempt to follow the dynamics of an explosive event. Such models may take the form of singular, degenerate, reaction-diffusion equations of the quenching type, that is, the temporal derivative blows up in finite time while the solution remains bounded. Theoretical and numerical investigations have proved difficult for even the simplest of geometries and mathematical degeneracies. Quenching domains are known to exist for piecewise smooth boundaries, but often lack theoretical estimates. Rectangular geometries have been primarily studied. Here, this acquired knowledge is utilized to determine new theoretical estimates to quenching domains for arbitrary piecewise, smooth, connected geometries. Elliptical domains are of primary interest and a Peaceman-Rachford splitting algorithm is then developed that employs temporal adaptation and nonuniform grids. Rigorous numerical analysis ensures numerical solution monotonicity, positivity, and linear stability of the proposed algorithm. Simulation experiments are provided to illustrate the accomplishments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1401/1401.7553v1.pdf"}
{"id": "1403.1546", "abstract": "  The interactions among the elementary components of many complex systems can be qualitatively different. Such systems are therefore naturally described in terms of multiplex or multi-layer networks, i.e. networks where each layer stands for a different type of interaction between the same set of nodes. There is today a growing interest in understanding when and why a description in terms of a multiplex network is necessary and more informative than a single-layer projection. Here, we contribute to this debate by presenting a comprehensive study of correlations in multiplex networks. Correlations in node properties, especially degree-degree correlations, have been thoroughly studied in single-layer networks. Here we extend this idea to investigate and characterize correlations between the different layers of a multiplex network. Such correlations are intrinsically multiplex, and we first study them empirically by constructing and analyzing several multiplex networks from the real-world. In particular, we introduce various measures to characterize correlations in the activity of the nodes and in their degree at the different layers, and between activities and degrees. We show that real-world networks exhibit indeed non-trivial multiplex correlations. For instance, we find cases where two layers of the same multiplex network are positively correlated in terms of node degrees, while other two layers are negatively correlated. We then focus on constructing synthetic multiplex networks, proposing a series of models to reproduce the correlations observed empirically and/or to assess their relevance. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.1546v2.pdf"}
{"id": "1403.5031", "abstract": "  We consider the problem of deriving an explicit approximate solution of the nonlinear power equations that describe a balanced power distribution network. We give sufficient conditions for the existence of a practical solution to the power flow equations, and we propose an approximation that is linear in the active and reactive power demands of the PQ buses. For this approximation, which is valid for generic power line impedances and grid topology, we derive a bound on the approximation error as a function of the grid parameters. We illustrate the quality of the approximation via simulations, we show how it can also model the presence of voltage controlled (PV) buses, and we discuss how it generalizes the DC power flow model to lossy networks. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1403/1403.5031v4.pdf"}
{"id": "1404.2754", "abstract": "  We study the relaxation dynamics of photoexcited Fe-II complexes dissolved in water and identify the relaxation pathway which the molecular complex follows in presence of a hydration shell of bound water at the interface between the complex and the solvent. Starting from a low-spin state, the photoexcited complex can reach the high-spin state via a cascade of different possible transitions involving electronic as well as vibrational relaxation processes. By numerically exact path integral calculations for the relaxational dynamics of a continuous solvent model, we find that the vibrational life times of the intermittent states are of the order of a few ps. Since the electronic rearrangement in the complex occurs on the time scale of about 100 fs, we find that the complex first rearranges itself in a high-spin and highly excited vibrational state, before it relaxes its energy to the solvent via vibrational relaxation transitions. By this, the relaxation pathway can be clearly identified. We find that the life time of the vibrational states increases with the size of the complex (within a spherical model), but decreases with the thickness of the hydration shell, indicating that the hydration shell acts as an additional source of fluctuations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.2754v1.pdf"}
{"id": "1404.4420", "abstract": "  A model to estimate the asymptotic isotropic mutual information of a multiantenna channel is considered. Using a block-based dynamics and the angle diversity of the system, we derived what may be thought of as the operator-valued version of the Kronecker correlation model. This model turns out to be more flexible than the classical version, as it incorporates both an arbitrary channel correlation and the correlation produced by the asymptotic antenna patterns. A method to calculate the asymptotic isotropic mutual information of the system is established using operator-valued free probability tools. A particular case is considered in which we start with explicit Cauchy transforms and all the computations are done with diagonal matrices, which make the implementation simpler and more efficient. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.4420v2.pdf"}
{"id": "1404.4540", "abstract": "  We analyze a distributed information network in which each node has access to the information contained in a limited set of nodes (its neighborhood) at a given time. A collective computation is carried out in which each node calculates a value that implies all information contained in the network (in our case, the average value of a variable that can take different values in each network node). The neighborhoods can change dynamically by exchanging neighbors with other nodes. The results of this collective calculation show rapid convergence and good scalability with the network size. These results are compared with those of a fixed network arranged as a square lattice, in which the number of rounds to achieve a given accuracy is very high when the size of the network increases. The results for the evolving networks are interpreted in light of the properties of complex networks and are directly relevant to the diameter and characteristic path length of the networks, which seem to express \"small world\" properties. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.4540v1.pdf"}
{"id": "1404.6216", "abstract": "  The term \"CoRE kernel\" stands for correlation-resemblance kernel. In many applications (e.g., vision), the data are often high-dimensional, sparse, and non-binary. We propose two types of (nonlinear) CoRE kernels for non-binary sparse data and demonstrate the effectiveness of the new kernels through a classification experiment. CoRE kernels are simple with no tuning parameters. However, training nonlinear kernel SVM can be (very) costly in time and memory and may not be suitable for truly large-scale industrial applications (e.g. search). In order to make the proposed CoRE kernels more practical, we develop basic probabilistic hashing algorithms which transform nonlinear kernels into linear kernels. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.6216v1.pdf"}
{"id": "1404.6346", "abstract": "  The extended Bose-Hubbard model for a double-well potential with pair tunneling is studied through both exact diagonalization and mean field theory (MFT). When pair tunneling is strong enough, the ground state wavefunction predicted by the MFT is complex and doubly degenerate while the quantum ground state wavefunction is always real and unique. The time reversal symmetry is spontaneously broken when the system transfers from the quantum ground state into one of the mean field ground states upon a small perturbation. As the gap between the lowest two levels decreases exponentially with particle number, the required perturbation inducing the spontaneous symmetry breaking (SSB) is infinitesimal for particle number of typical cold atom systems. The quantum ground state is further analyzed with the Penrose-Onsager criterion, and is found to be a fragmented condensate. The state also develops the pair correlation and has non-vanishing pair order parameter instead of the conventional single particle order parameter. When this model is generalized to optical lattice, a pair superfluid can be generated. The mean field ground state can be regarded as effective ground state in this simple model. The detailed computation for this model enables us to offer an in-depth discussion of the relation between SSB and effective ground state, giving a glimpse on how nonlinearity arises in the SSB of a quantum system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1404/1404.6346v1.pdf"}
{"id": "1405.1360", "abstract": "  An association rule is statistically significant, if it has a small probability to occur by chance. It is well-known that the traditional frequency-confidence framework does not produce statistically significant rules. It can both accept spurious rules (type 1 error) and reject significant rules (type 2 error). The same problem concerns other commonly used interestingness measures and pruning heuristics.   In this paper, we inspect the most common measure functions - frequency, confidence, degree of dependence, χ^2, correlation coefficient, and J-measure - and redundancy reduction techniques. For each technique, we analyze whether it can make type 1 or type 2 error and the conditions under which the error occurs. In addition, we give new theoretical results which can be use to guide the search for statistically significant association rules. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.1360v1.pdf"}
{"id": "1405.3273", "abstract": "  We report an implementation of self-consistent Green's function many-body theory within a second-order approximation (GF2) for application with molecular systems. This is done by iterative solution of the Dyson equation expressed in matrix form in an atomic orbital basis, where the Green's function and self-energy are built on the imaginary frequency and imaginary time domain respectively, and fast Fourier transform is used to efficiently transform these quantities as needed. We apply this method to several archetypical examples of strong correlation, such as a H_32 finite lattice that displays a highly multireference electronic ground state even at equilibrium lattice spacing. In all cases GF2 gives a physically meaningful description of the metal to insulator transition in these systems, without resorting to spin-symmetry breaking. Our results show that self-consistent Green's function many-body theory offers a viable route to describing strong correlations while remaining within a computationally tractable single-particle formalism. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.3273v1.pdf"}
{"id": "1405.7241", "abstract": "  We show that a rate of conditional Shannon entropy reduction, characterizing the learning of an internal process about an external process, is bounded by the thermodynamic entropy production. This approach allows for the definition of an informational efficiency that can be used to study cellular information processing. We analyze three models of increasing complexity inspired by the E. coli sensory network, where the external process is an external ligand concentration jumping between two values. We start with a simple model for which ATP must be consumed so that a protein inside the cell can learn about the external concentration. With a second model for a single receptor we show that the rate at which the receptor learns about the external environment can be nonzero even without any dissipation inside the cell since chemical work done by the external process compensates for this learning rate. The third model is more complete, also containing adaptation. For this model we show inter alia that a bacterium in an environment that changes at a very slow time-scale is quite inefficient, dissipating much more than it learns. Using the concept of a coarse-grained learning rate, we show for the model with adaptation that while the activity learns about the external signal the option of changing the methylation level increases the concentration range for which the learning rate is substantial. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1405/1405.7241v2.pdf"}
{"id": "1406.0251", "abstract": "  We consider a one-dimensional totally asymmetric exclusion process on a ring with extended inhomogeneities, consisting of several segments with different hopping rates. Depending upon the underlying inhomogeneity configurations and for moderate densities, our model displays both localised (LDW) and delocalised (DDW) domain walls and delocalisation transitions of LDWs in the steady states. Our results allow us to construct the possible steady state density profiles for an arbitrary number of segments with unequal hopping rates. We explore the scaling properties of the fluctuations of LDWs and DDWs. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.0251v2.pdf"}
{"id": "1406.6580", "abstract": "  The Lutz-Kelker correction is intended to give an unbiased estimate for stellar parallaxes and magnitudes, but it is shown explicitly that it does not. This paradox results from the application of an argument about sample statistics to the treatment of individual stars, and involves the erroneous use of a frequency distribution in the manner of a probability density function considered as a Bayesian prior. It is shown that the Bayesian probability distribution for true parallax given the observed parallax of a selected star is independent of the distribution of other stars. Consequently the Lutz-Kelker correction should not be used for individual stars. This result has important implications for the RR Lyrae scale and for the interpretation of results from Gaia and Hipparcos. The Lutz-Kelker correction is a poor treatment of the Trumpler-Weaver bias which affects parallax limited samples. A true correction is calculated using numerical integration and confirmed by a Monte Carlo method. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1406/1406.6580v2.pdf"}
{"id": "1408.0399", "abstract": "  This paper considers the problem of constructing a direct coupling quantum observer for a closed linear quantum system. The proposed observer is shown to be able to estimate some but not all of the plant variables in a time averaged sense. A simple example and simulations are included to illustrate the properties of the observer. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.0399v2.pdf"}
{"id": "1408.1077", "abstract": "  Following up on earlier work, we investigate possible effects of a dressed quark-gluon vertex in heavy-light mesons. In particular, we study corrections to the popular rainbow-ladder truncation of the Dyson-Schwinger-Bethe-Salpeter equation system. We adopt a simple interaction kernel which reduces the resulting set of coupled integral equations to a set of coupled algebraic equations, which are solved numerically. In this way, we extend previous studies to quark-antiquark systems with unequal current-quark masses, at first for the pseudoscalar case, and investigate the resulting set of problems and solutions. We attempt to find patterns in - as well as to quantify corrections to - the rainbow-ladder truncation. In addition, we open this approach to phenomenological predictions of the heavy quark symmetry. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.1077v2.pdf"}
{"id": "1408.1411", "abstract": "  Recent experiments in ultracold atoms and photonic analogs have reported the implementation of artificial gauge fields in lattice systems, facilitating the realization of topological phases. Motivated by such advances, we investigate the Haldane honeycomb lattice tight-binding model, for bosons with local interactions at the average filling of one boson per site. We analyze the ground state phase diagram and uncover three distinct phases: a uniform superfluid (SF), a chiral superfluid (CSF) and a plaquette Mott insulator with local current loops (PMI). Nearest-neighbor and next-nearest neighbor currents distinguish CSF from SF, and the phase transition between them is first order. We apply bosonic dynamical mean field theory and exact diagonalization to obtain the phase diagram, complementing numerics with calculations of excitation spectra in strong and weak coupling perturbation theory. The characteristic density fluctuations, current correlation functions, and excitation spectra are measurable in ultracold atom experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.1411v2.pdf"}
{"id": "1408.5663", "abstract": "  Several types of AL-FEC (Application-Level FEC) codes for the Packet Erasure Channel exist. Random Linear Codes (RLC), where redundancy packets consist of random linear combinations of source packets over a certain finite field, are a simple yet efficient coding technique, for instance massively used for Network Coding applications. However the price to pay is a high encoding and decoding complexity, especially when working on GF(2^8), which seriously limits the number of packets in the encoding window. On the opposite, structured block codes have been designed for situations where the set of source packets is known in advance, for instance with file transfer applications. Here the encoding and decoding complexity is controlled, even for huge block sizes, thanks to the sparse nature of the code and advanced decoding techniques that exploit this sparseness (e.g., Structured Gaussian Elimination). But their design also prevents their use in convolutional use-cases featuring an encoding window that slides over a continuous set of incoming packets.   In this work we try to bridge the gap between these two code classes, bringing some structure to RLC codes in order to enlarge the use-cases where they can be efficiently used: in convolutional mode (as any RLC code), but also in block mode with either tiny, medium or large block sizes. We also demonstrate how to design compact signaling for these codes (for encoder/decoder synchronization), which is an essential practical aspect. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1408/1408.5663v1.pdf"}
{"id": "1410.7642", "abstract": "  Bistability is ubiquitous in biological systems. For example, bistability is found in many reaction networks that involve the control and execution of important biological functions, such as signalling processes. Positive feedback loops, composed of species and reactions, are necessary for bistability, and generally for multi-stationarity, to occur. These loops are therefore often used to illustrate and pinpoint the parts of a multi-stationary network that are relevant (`responsible') for the observed multi-stationarity. However positive feedback loops are generally abundant in reaction networks but not all of them are important for subsequent interpretation of the network's dynamics.   We present an automated procedure to determine the relevant positive feedback loops of a multi-stationary reaction network. The procedure only reports the loops that are relevant for multi-stationarity (that is, when broken multi-stationarity disappears) and not all positive feedback loops of the network. We show that the relevant positive feedback loops must be understood in the context of the network (one loop might be relevant for one network, but cannot create multi-stationarity in another). Finally, we demonstrate the procedure by applying it to several examples of signaling processes, including a ubiquitination and an apoptosis network, and to models extracted from the Biomodels database.   We have developed and implemented an automated procedure to find relevant positive feedback loops in reaction networks. The results of the procedure are useful for interpretation and summary of the network's dynamics. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1410/1410.7642v1.pdf"}
{"id": "1411.1215", "abstract": "  This paper argues that there are three fundamental challenges that need to be overcome in order to foster the adoption of big data technologies in non-computer science related disciplines: addressing issues of accessibility of such technologies for non-computer scientists, supporting the ad hoc exploration of large data sets with minimal effort and the availability of lightweight web-based frameworks for quick and easy analytics. In this paper, we address the above three challenges through the development of 'BigExcel', a three tier web-based framework for exploring big data to facilitate the management of user interactions with large data sets, the construction of queries to explore the data set and the management of the infrastructure. The feasibility of BigExcel is demonstrated through two Yahoo Sandbox datasets. The first dataset is the Yahoo Buzz Score data set we use for quantitatively predicting trending technologies and the second is the Yahoo n-gram corpus we use for qualitatively inferring the coverage of important events. A demonstration of the BigExcel framework and source code is available at http://bigdata.cs.st-andrews.ac.uk/projects/bigexcel-exploring-big-data-for-social-sciences/. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1411/1411.1215v1.pdf"}
{"id": "1411.4313", "abstract": "  Most uncertainties regarding the theoretical study of the neutrinoless double-beta decay are related to the accuracy of the nuclear matrix elements that appear in the expressions of the lifetimes. We calculate the nuclear matrix elements for the 0νββ decay of ^130Te in a shell model approach, using a recently proposed effective Hamiltonian. To ensure the reliability of the results, we investigate this Hamiltonian by performing calculations of spectroscopic quantities and comparing them to the latest experimental data available, and we analyze the 2νββ and the 0νββ decay nuclear matrix elements of ^136Xe. Finally, we report new nuclear matrix for the ^130Te considering the light neutrino exchange and heavy neutrino exchange mechanisms, alongside with an overview of some recent values reported in the literature. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1411/1411.4313v1.pdf"}
{"id": "1412.7153", "abstract": "  A locally gauge-invariant theory of the spin response of a thin film of ^3He-B film is given that describes fluctuation effects arising from the coupled dynamics of the superconducting order parameter (the collective mode) and in-gap Majorana surface states. In contrast to a mean-field calculation of the spin response, which predicts a nonzero imaginary longitudinal spin susceptibility at frequencies inside the bulk gap due to absorption from the Majorana states, our gauge-invariant theory shows that this response is strongly suppressed above the collective mode frequency and vanishes if dipole-dipole interactions are neglected. In the presence of dipole-dipole interactions, in sufficiently thin films, and at ultra-low temperatures, the Majorana states lead to a distinctive magnetic-field- and temperature-dependent damping of the collective mode, a feature that may be observable in longitudinal NMR experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1412/1412.7153v2.pdf"}
{"id": "1502.04613", "abstract": "  Plants are sensitive to thermal and electrical effects; yet the coupling of both, known as thermoelectricity, and its quantitative measurement in vegetal systems never were reported. We recorded the thermoelectric response of bean sprouts under various thermal conditions and stress. The obtained experimental data unambiguously demonstrate that a temperature difference between the roots and the leaves of a bean sprout induces a thermoelectric voltage between these two points. Basing our analysis of the data on the force-flux formalism of linear response theory, we found that the strength of the vegetal equivalent to the thermoelectric coupling is one order of magnitude larger than that in the best thermoelectric materials. Experimental data also show the importance of the thermal stress variation rate in the plant's electrophysiological response. Therefore, thermoelectric effects are sufficiently important to partake in the complex and intertwined processes of energy and matter transport within plants. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1502/1502.04613v1.pdf"}
{"id": "1505.02972", "abstract": "  We investigate the effects of homogeneous general dark energy on the non-linear matter perturbation in fully general relativistic context. The equation for the density contrast contains even at linear order new contributions which are non-zero for general dark energy. Taking into account the next-leading-order corrections, we derive the total power spectrum in real and redshift spaces. We find that the observable galaxy power spectrum deviates from the LambdaCDM spectrum, which is nearly identical to that in the Einstein-de Sitter universe, and the relative difference is about 10", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.02972v2.pdf"}
{"id": "1505.03180", "abstract": "  A dielectric drop suspended in conducting liquid and subjected to an uniform electric field deforms into an ellipsoid whose major axis is either perpendicular or tilted (due to Quincke rotation effect) relative to the applied field. We experimentally study the effect of surface-adsorbed colloidal particles on these classic electrohydrodynamic phenomena. We observe that at high surface coverage (>90", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.03180v1.pdf"}
{"id": "1505.07501", "abstract": "  Self-assembly in the laboratory can now yield `information-rich' nanostructures in which each component is of a distinct type and has a defined spatial position. Ensuring the thermodynamic stability of such structures requires inter-component interaction energies to increase logarithmically with structure size, in order to counter the entropy gained upon mixing component types in solution. However, self-assembly in the presence of strong interactions results in general in kinetic trapping, so suggesting a limit to the size of an (equilibrium) structure that can be self-assembled from distinguishable components. Here we study numerically a two-dimensional hierarchical assembly scheme already considered in experiment. We show that this scheme is immune to the kinetic traps associated with strong `native' interactions (interactions designed to stabilize the intended structure), and so, in principle, offers a way to make large information-rich structures. In this scheme the size of an assembled structure scales exponentially with the stage of assembly, and assembly can continue as long as random motion is able to bring structures into contact. The resulting superstructure could provide a template for building in the third dimension. The chief drawback of this scheme is that it is particularly susceptible to kinetic traps that result from `non-native' interactions (interactions not required to stabilize the intended structure); the scale on which such a scheme can be realized therefore depends upon how effectively this latter kind of interaction can be suppressed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1505/1505.07501v2.pdf"}
{"id": "1506.01106", "abstract": "  Resource scheduling in infrastructure as a service (IaaS) is one of the keys for large-scale Cloud applications. Extensive research on all issues in real environment is extremely difficult because it requires developers to consider network infrastructure and the environment, which may be beyond the control. In addition, the network conditions cannot be controlled or predicted. Performance evaluations of workload models and Cloud provisioning algorithms in a repeatable manner under different configurations are difficult. Therefore, simulators are developed. To understand and apply better the state-of-the-art of cloud computing simulators, and to improve them, we study four known open-source simulators. They are compared in terms of architecture, modeling elements, simulation process, performance metrics and scalability in performance. Finally, a few challenging issues as future research trends are outlined. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1506/1506.01106v1.pdf"}
{"id": "1507.06294", "abstract": "  Past studies have already shown that stars in open clusters are chemically homogeneous (e.g. De Silva et al. 2006, 2007 and 2009). These results support the idea that stars born from the same giant molecular cloud should have the same chemical composition. In this context, the chemical tagging technique was proposed by Freeman     Bland-Hawthorn 2002. The principle is to recover disrupted stellar clusters by looking only to the stellar chemical composition. In order to evaluate the feasibility of this approach, it is necessary to test if we can distinguish between stars born from different molecular clouds. For this purpose, we studied the chemical composition of stars in 32 old and intermediate-age open clusters, and we applied machine learning algorithms to recover the original cluster by only considering the chemical signatures. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1507/1507.06294v2.pdf"}
{"id": "1509.01770", "abstract": "  We theoretically and experimentally investigate tensor-based regression and classification. Our focus is regularization with various tensor norms, including the overlapped trace norm, the latent trace norm, and the scaled latent trace norm. We first give dual optimization methods using the alternating direction method of multipliers, which is computationally efficient when the number of training samples is moderate. We then theoretically derive an excess risk bound for each tensor norm and clarify their behavior. Finally, we perform extensive experiments using simulated and real data and demonstrate the superiority of tensor-based learning methods over vector- and matrix-based learning methods. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1509/1509.01770v1.pdf"}
{"id": "1510.03001", "abstract": "  Twisted links are a generalization of virtual links. As virtual links correspond to abstract links on orientable surfaces, twisted links correspond to abstract links on (possibly non-orientable) surfaces. In this paper, we introduce the notion of the double covering of a twisted link. It is defined by considering the orientation double covering of an abstract link or alternatively by constructing a diagram called a double covering diagram. We also discuss links in thickened surfaces, their diagrams and their stable equivalence classes. Bourgoin's twisted knot group is understood as the virtual knot group of the double covering. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.03001v3.pdf"}
{"id": "1510.07176", "abstract": "  In the Cloud Radio Access Network (C-RAN) architecture, a Control Unit (CU) implements the baseband processing functionalities of a cluster of Base Stations (BSs), which are connected to it through a fronthaul network. This architecture enables centralized processing at the CU, and hence the implementation of enhanced interference mitigation strategies, but it also entails an increased decoding latency due to the transport on the fronthaul network. The fronthaul latency may offset the benefits of centralized processing when considering the performance of protocols at layer 2 and above. This letter studies the impact of fronthaul latency on the performance of standard Automatic Retransmission reQuest (ARQ) protocols, namely Stop and Wait, Go-Back-N and Selective Repeat. The performance of the C-RAN architecture in terms of throughput and efficiency is compared to the that of a conventional cellular system with local processing, as well as with that of a proposed hybrid C-RAN system in which BSs can perform decoding. The dynamics of the system are modeled as a multi-dimensional Markov process that includes sub-chains to capture the temporal correlation of interference and channel gains. Numerical results yield insights into the impact of system parameters such as fronthaul latency and signal-to-interference ratio on different ARQ protocols. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1510/1510.07176v1.pdf"}
{"id": "1511.01533", "abstract": "  A crucial aspect of understanding planet formation is determining the binarity of the host stars. Results from radial velocity surveys and the follow-up of Kepler exoplanet candidates have demonstrated that stellar binarity certainly does not exclude the presence of planets in stable orbits and the configuration may in fact be relatively common. Here we present new results for the 30 Arietis system which confirms that the B component hosts both planetary and stellar companions. Keck AO imaging provides direct detection of the stellar companion and additional radial velocity data are consistent with an orbiting star. We present a revised orbit of the known planet along with photometry during predicted transit times. Finally, we provide constraints on the properties of the stellar companion based on orbital stability considerations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1511/1511.01533v2.pdf"}
{"id": "1512.01314", "abstract": "  In this article, we propose a novel Winner-Take-All (WTA) architecture employing neurons with nonlinear dendrites and an online unsupervised structural plasticity rule for training it. Further, to aid hardware implementations, our network employs only binary synapses. The proposed learning rule is inspired by spike time dependent plasticity (STDP) but differs for each dendrite based on its activation level. It trains the WTA network through formation and elimination of connections between inputs and synapses. To demonstrate the performance of the proposed network and learning rule, we employ it to solve two, four and six class classification of random Poisson spike time inputs. The results indicate that by proper tuning of the inhibitory time constant of the WTA, a trade-off between specificity and sensitivity of the network can be achieved. We use the inhibitory time constant to set the number of subpatterns per pattern we want to detect. We show that while the percentage of successful trials are 92", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.01314v1.pdf"}
{"id": "1512.04591", "abstract": "  Tumor development is an evolutionary process in which a heterogeneous population of cells with differential growth capabilities compete for resources in order to gain a proliferative advantage. What are the minimal ingredients needed to recreate some of the emergent features of such a developing complex ecosystem? What is a tumor doing before we can detect it? We outline a mathematical model, driven by a stochastic Moran process, in which cancer cells and healthy cells compete for dominance in the population. Each are assigned payoffs according to a Prisoner's Dilemma evolutionary game where the healthy cells are the cooperators and the cancer cells are the defectors. With point mutational dynamics, heredity, and a fitness landscape controlling birth and death rates, natural selection acts on the cell population and simulated \"cancer-like\" features emerge, such as Gompertzian tumor growth driven by heterogeneity, the log-kill law which (linearly) relates therapeutic dose density to the (log) probability of cancer cell survival, and the Norton-Simon hypothesis which (linearly) relates tumor regression rates to tumor growth rates. We highlight the utility, clarity, and power that such models provide, despite (and because of) their simplicity and built-in assumptions. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.04591v4.pdf"}
{"id": "1512.07471", "abstract": "  We study thermoelectric transport through a coherent molecular conductor connected to two electron and two phonon baths using the nonequilibrium Green's function method. We focus on the mutual drag between electron and phonon transport as a result of `momentum' transfer, which happens only when there are at least two phonon degrees of freedom. After deriving expressions for the linear drag coefficients, obeying the Onsager relation, we further investigate their effect on nonequilibrium transport. We show that the drag effect is closely related to two other phenomena: (1) adiabatic charge pumping through a coherent conductor; (2) the current-induced nonconservative and effective magnetic forces on phonons. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1512/1512.07471v2.pdf"}
{"id": "1601.06439", "abstract": "  What makes a person pick certain tags over others when tagging an image? Does the order that a person presents tags for a given image follow an implicit bias that is personal? Can these biases be used to improve existing automated image tagging systems? We show that tag ordering, which has been largely overlooked by the image tagging community, is an important cue in understanding user tagging behavior and can be used to improve auto-tagging systems. Inspired by the assumption that people order their tags, we propose a new way of measuring tag preferences, and also propose a new personalized tagging objective function that explicitly considers a user's preferred tag orderings. We also provide a (partially) greedy algorithm that produces good solutions to our new objective and under certain conditions produces an optimal solution. We validate our method on a subset of Flickr images that spans 5000 users, over 5200 tags, and over 90,000 images. Our experiments show that exploiting personalized tag orders improves the average performance of state-of-art approaches both on per-image and per-user bases. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.06439v1.pdf"}
{"id": "1601.06840", "abstract": "  We measure strong radio-frequency (RF) electric fields using rubidium Rydberg atoms prepared in a room-temperature vapor cell as field sensors. Electromagnetically induced transparency is employed as an optical readout. We RF-modulate the 60S_1/2 and 58D_5/2 Rydberg states with 50 MHz and 100 MHz fields, respectively. For weak to moderate RF fields, the Rydberg levels become Stark-shifted, and sidebands appear at even multiples of the driving frequency. In high fields, the adjacent hydrogenic manifold begins to intersect the shifted levels, providing rich spectroscopic structure suitable for precision field measurements. A quantitative description of strong-field level modulation and mixing of S and D states with hydrogenic states is provided by Floquet theory. Additionally, we estimate the shielding of DC electric fields in the interior of the glass vapor cell. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1601/1601.06840v1.pdf"}
{"id": "1602.00781", "abstract": "  We propose a scheme for the creation of robust entanglement between a movable mirror and atomic ensemble at the macroscopic level in coupled optomechanical system. In experimentally accessible parameter regimes, we show that critical temperature of the bipartite continuous variable entanglement in our scheme can be raised from previous 24 K [Vitali et al., Phys. Rev. Lett. 98, 030405 (2007)] and 20 K [Genes et al., Phys. Rev. A 77, 050307(R) (2008)] to 32 K. We also investigate the entanglement transfer based on this coupled system. The scheme can be used for the realization of quantum memories for continuous variable quantum information processing and quantum-limited displacement measurements. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.00781v1.pdf"}
{"id": "1602.07579", "abstract": "  In traditional cognitive radio networks, secondary users (SUs) typically access the spectrum of primary users (PUs) by a two-stage \"listen-before-talk\" (LBT) protocol, i.e., SUs sense the spectrum holes in the first stage before transmitting in the second. However, there exist two major problems: 1) transmission time reduction due to sensing, and 2) sensing accuracy impairment due to data transmission. In this paper, we propose a \"listen-and-talk\" (LAT) protocol with the help of full-duplex (FD) technique that allows SUs to simultaneously sense and access the vacant spectrum. Spectrum utilization performance is carefully analyzed, with the closed-form spectrum waste ratio and collision ratio with the PU provided. Also, regarding the secondary throughput, we report the existence of a tradeoff between the secondary transmit power and throughput. Based on the power-throughput tradeoff, we derive the analytical local optimal transmit power for SUs to achieve both high throughput and satisfying sensing accuracy. Numerical results are given to verify the proposed protocol and the theoretical results. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.07579v1.pdf"}
{"id": "1602.08341", "abstract": "  It is commonly assumed that if the optical metric of a dielectric medium is identical to the metric of a vacuum space-time then light propagation through the dielectric mimics light propagation in the vacuum. However, just as the curved surface of the Earth cannot be mapped into a flat plane without distortion of some surface features, so too is it impossible to project the behavior of light from the vacuum into a dielectric analog residing in Minkowski space-time without introducing distortions. We study the covariance properties of dielectric analog space-times and the kinematics of a congruence of light in the analog, and show how certain features can be faithfully emulated in the analog depending on the choice of projection, but that not all features can be simultaneously emulated without distortion. These findings indicate conceptual weaknesses in the idea of using analog space-times as a basis for transformation optics, and we show that a certain formulation of transformation optics closely related to analog space-times resolves these issues. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1602/1602.08341v3.pdf"}
{"id": "1603.02947", "abstract": "  We discuss the categorization of 20 quantum mechanics problems by physics professors and undergraduate students from two honors-level quantum mechanics courses. Professors and students were asked to categorize the problems based upon similarity of solution. We also had individual discussions with professors who categorized the problems. Faculty members' categorizations were overall rated higher than those of students by three faculty members who evaluated all of the categorizations. The categories created by faculty members were more diverse compared to the categories they created for a set of introductory mechanics problems. Some faculty members noted that the categorization of introductory physics problems often involves identifying fundamental principles relevant for the problem, whereas in upper-level undergraduate quantum mechanics problems, it mainly involves identifying concepts and procedures required to solve the problem. Moreover, physics faculty members who evaluated others' categorizations expressed that the task was very challenging and they sometimes found another person's categorization to be better than their own. They also rated some concrete categories such as \"hydrogen atom\" or \"simple harmonic oscillator\" higher than other concrete categories such as \"infinite square well\" or \"free particle\". ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1603/1603.02947v1.pdf"}
{"id": "1605.03153", "abstract": "  In this work the accuracy of the Actuator Line Model (ALM) in Large Eddy Simulations of wind turbine flow is studied under the specific conditions of very coarse spatial resolutions. For finely-resolved conditions, it is known that ALM provides better accuracy compared to the standard Actuator Disk Model (ADM) without rotation. However, we show here that on very coarse resolutions, flow induction occurring at rotor scales can affect the predicted inflow angle and can adversely affect the ALM predictions. We first provide an illustration of coarse LES to reproduce wind tunnel measurements. The resulting flow predictions are good, but the challenges in predicting power outputs from the detailed ALM motivate more detailed analysis on a case with uniform inflow. We present a theoretical framework to compare the filtered quantities that enter the Large-Eddy Simulation equations as body forces with a scaling relation between the filtered and unfiltered quantities. The study aims to apply the theoretical derivation to the simulation framework and improve the current results for an ALM, especially in the near wake where the largest differences are observed. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1605/1605.03153v1.pdf"}
{"id": "1607.05481", "abstract": "  We introduce an orbital-optimized double-hybrid (DH) scheme using the optimized-effective-potential (OEP) method. The orbitals are optimized using a local potential corresponding to the complete exchange-correlation energy expression including the second-order Møller-Plesset (MP2) correlation contribution. We have implemented a one-parameter version of this OEP-based self-consistent DH scheme using the BLYP density-functional approximation and compared it to the corresponding non-self-consistent DH scheme for calculations on a few closed-shell atoms and molecules. While the OEP-based self-consistency does not provide any improvement for the calculations of ground-state total energies and ionization potentials, it does improve the accuracy of electron affinities and restores the meaning of the LUMO orbital energy as being connected to a neutral excitation energy. Moreover, the OEP-based self-consistent DH scheme provides reasonably accurate exchange-correlation potentials and correlated densities. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1607/1607.05481v2.pdf"}
{"id": "1608.00101", "abstract": "  Private comparison is a primitive for many cryptographic tasks, and recently several schemes for the quantum private comparison (QPC) have been proposed, where two users can compare the equality of their secrets with the help of a semi-honest third party (TP) without knowing each other's secret and without disclosing the same to the TP. In the exisiting schemes, secrecy is obtained by using conjugate coding, and considering all participants as quantum users who can perform measurement(s) and/or create states in basis other than computational basis. In contrast, here we propose two new protocols for QPC, first of which does not use conjugate coding (uses orthogonal states only) and the second one allows the users other than TP to be classical whose activities are restricted to either reflecting a quantum state or measuring it in computational basis. Further, the performance of the protocols is evaluated under various noise models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.00101v2.pdf"}
{"id": "1608.02509", "abstract": "  We study formal counterparts of Hurewicz fibrations and related topological notions in elementary toposes with NNO. The constructions are based on a specific notion of interval and lead to a structure of category of fibrant objects on toposes equipped with such a datum. We get in fact slightly more as the building blocks are derived from a weak factorisation system. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.02509v4.pdf"}
{"id": "1608.04892", "abstract": "  Various small-scale structures abound in the solar atmosphere above active regions, playing an important role in the dynamics and evolution therein. We report on a new class of small-scale transition region structures in active regions, characterized by strong emissions but extremely narrow Si IV line profiles as found in observations taken with the Interface Region Imaging Spectrograph (IRIS). Tentatively named as Narrow-line-width UV bursts (NUBs), these structures are located above sunspots and comprise of one or multiple compact bright cores at sub-arcsecond scales. We found six NUBs in two datasets (a raster and a sit-and-stare dataset). Among these, four events are short-living with a duration of ∼10 mins while two last for more than 36 mins. All NUBs have Doppler shifts of 15–18 km/s, while the NUB found in sit-and-stare data possesses an additional component at ∼50 km/s found only in the C II and Mg II lines. Given that these events are found to play a role in the local dynamics, it is important to further investigate the physical mechanisms that generate these phenomena and their role in the mass transport in sunspots. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.04892v1.pdf"}
{"id": "1608.08382", "abstract": "  We study Kitaev model in one-dimension with open boundary condition by using exact analytic methods for non-interacting system at zero chemical potential as well as in the symmetric case of Δ = t, and by using density-matrix-renormalizationgroup method for interacting system with nearest neighbor repulsion interaction. We suggest and examine an edge correlation function of Majorana fermions to characterize the long range order in the topological superconducting states and study the phase diagram of the interating Kitaev chain. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.08382v4.pdf"}
{"id": "1608.08665", "abstract": "  In this paper we study the approximation of an optimal control problem for linear para­bolic PDEs with model order reduction based on Proper Orthogonal Decomposition (POD-MOR). POD-MOR is a Galerkin approach where the basis functions are obtained upon information contained in time snapshots of the parabolic PDE related to given input data. In the present work we show that for POD-MOR in optimal control of parabolic equations it is important to have knowledge about the controlled system at the right time instances. We propose to determine the time instances (snapshot locations) by an a-posteriori error control concept. This method is based on a reformulation of the optimality system of the underlying optimal control problem as a second order in time and fourth order in space elliptic system which is approximated by a space-time finite element method. Finally, we present numerical tests to illustrate our approach and to show the effectiveness of the method in comparison to existing approaches. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1608/1608.08665v1.pdf"}
{"id": "1609.00226", "abstract": "  Recently [Cavalcanti et al. Nat Commun 6, 7941 (2015)] proposed a method to certify the presence of entanglement in asymmetric networks, where some users do not have control over the measurements they are performing. Such asymmetry naturally emerges in realistic situtations, such as in cryptographic protocols over quantum networks. Here we implement such \"semi-device independent\" techniques to experimentally witness all types of entanglement on a three-qubit photonic W state. Furthermore we analise the amount of genuine randomness that can be certified in this scenario from any bipartition of the three-qubit W state. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1609/1609.00226v2.pdf"}
{"id": "1610.02346", "abstract": "  We analyze the sensitivity of thermal fits to heavy-ion hadron yield data of ALICE and NA49 collaborations to the systematic uncertainties in the hadron resonance gas (HRG) model related to the modeling of the eigenvolume interactions. We find a surprisingly large sensitivity in extraction of chemical freeze-out parameters to the assumptions regarding eigenvolumes of different hadrons. We additionally study the effect of including yields of light nuclei into the thermal fits to LHC data and find even larger sensitivity to the modeling of their eigenvolumes. The inclusion of light nuclei yields, thus, may lead to further destabilization of thermal fits. Our results show that modeling of eigenvolume interactions plays a crucial role in thermodynamics of HRG and that conclusions based on a non-interacting HRG are not unique. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.02346v1.pdf"}
{"id": "1610.06939", "abstract": "  We derive new empirical calibrations for strong-line diagnostics of gas phase metallicity in local star forming galaxies by uniformly applying the Te method over the full metallicity range probed by the Sloan Digital Sky Survey (SDSS). To measure electron temperatures at high metallicity, where the auroral lines needed are not detected in single galaxies, we stacked spectra of more than 110,000 galaxies from the SDSS in bins of log[O II]/Hβ and log[O III]/Hβ. This stacking scheme does not assume any dependence of metallicity on mass or star formation rate, but only that galaxies with the same line ratios have the same oxygen abundance. We provide calibrations which span more than 1 dex in metallicity and are entirely defined on a consistent absolute Te metallicity scale for galaxies. We apply our calibrations to the SDSS sample and find that they provide consistent metallicity estimates to within 0.05 dex. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1610/1610.06939v1.pdf"}
{"id": "1611.01164", "abstract": "  The relation between network structure and dynamics is determinant for the behavior of complex systems in numerous domains. An important long-standing problem concerns the properties of the networks that optimize the dynamics with respect to a given performance measure. Here we show that such optimization can lead to sensitive dependence of the dynamics on the structure of the network. Specifically, using diffusively coupled systems as examples, we demonstrate that the stability of a dynamical state can exhibit sensitivity to unweighted structural perturbations (i.e., link removals and node additions) for undirected optimal networks and to weighted perturbations (i.e., small changes in link weights) for directed optimal networks. As mechanisms underlying this sensitivity, we identify discontinuous transitions occurring in the complement of undirected optimal networks and the prevalence of eigenvector degeneracy in directed optimal networks. These findings establish a unified characterization of networks optimized for dynamical stability, which we illustrate using Turing instability in activator-inhibitor systems, synchronization in power-grid networks, network diffusion, and several other network processes. Our results suggest that the network structure of a complex system operating near an optimum can potentially be fine-tuned for a significantly enhanced stability compared to what one might expect from simple extrapolation. On the other hand, they also suggest constraints on how close to the optimum the system can be in practice. Finally, the results have potential implications for biophysical networks, which have evolved under the competing pressures of optimizing fitness while remaining robust against perturbations. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.01164v3.pdf"}
{"id": "1611.05945", "abstract": "  We introduce the notion of rational links in the solid torus. We show that rational links in the solid torus are fully characterized by rational tangles, and hence by the continued fraction of the rational tangle. Furthermore, we generalize this by giving an infinite family of ambient isotopy invariants of colored diagrams in the Kauffman bracket skein module of an oriented surface. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.05945v5.pdf"}
{"id": "1611.06295", "abstract": "  We present an efficient post-processing method for calculating the electronic structure of nanosystems based on the divide-and-conquer approach to density functional theory (DC-DFT), in which a system is divided into subsystems whose electronic structure is solved separately. In this post process, the Kohn-Sham Hamiltonian of the total system is easily derived from the orbitals and orbital energies of subsystems obtained by DC-DFT without time-consuming and redundant computation. The resultant orbitals spatially extended over the total system are described as linear combinations of the orbitals of the subsystems. The size of the Hamiltonian matrix can be much reduced from that for conventional calculation, so that our method is fast and applicable to general huge systems for investigating the nature of electronic states. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.06295v2.pdf"}
{"id": "1611.06854", "abstract": "  In this article we study the two-dimensional (2D) ultracold Fermi gas with weak impurity in the framework of mean-field theory where the impurity is introduced through Gaussian fluctuations. We have investigated the role of the impurity by studying the experimentally accessible quantities such as condensate fraction and equation of state of the ultracold systems. Our analysis reveals that, at the crossover the disorder enhances superfluidity, which we attribute to the unique nature of the unitary region and to the dimensional effect. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1611/1611.06854v1.pdf"}
{"id": "1612.01699", "abstract": "  Nuclear spin relaxation is studied in n-GaAs thick layers and microcavity samples with different electron densities. We reveal that both in metallic samples where electrons are free and mobile, and in insulating samples, where electrons are localized, nuclear spin relaxation is strongly enhanced at low magnetic field. The origin of this effect could reside in the quadrupole interaction between nuclei and fluctuating electron charges, that has been proposed to drive nuclear spin dynamics at low magnetic fields in the insulating samples. The characteristic values of these magnetic fields are given by dipole-dipole interaction between nuclei in bulk samples, and are greatly enhanced in microcavities, presumably due to additional strain, inherent to micro and nanostructures. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.01699v2.pdf"}
{"id": "1612.01972", "abstract": "  We investigate a new class of scalar multi-galileon models, which is not included in the commonly admitted general formulation of generalized multi-galileons. The Lagrangians of this class of models, some of them having already been introduced in previous works, are specific to multi-galileon theories, and vanish in the single galileon case. We examine them in details, discussing in particular some hidden symmetry properties which can be made explicit by adding total derivatives to these Lagrangians. These properties allow us to describe the possible dynamics for these new Lagrangians in the case of multi-galileons in the fundamental representation of a SO(N) and SU(N) global symmetry group, as well as in the adjoint representation of a SU(N) global symmetry group. We perform in parallel an exhaustive examination of some of these models, finding a complete agreement with the dynamics obtained using the symmetry properties. Finally, we conclude by discussing what could be the most general multi-galileon theory, as well as the link between scalar and vector multi-galileon models. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.01972v2.pdf"}
{"id": "1612.02588", "abstract": "  NGC 147 and NGC 185 are two of the most massive satellites of the Andromeda galaxy (M 31). Close together in the sky, of similar mass and morphological type dE, they possess different amounts of interstellar gas and tidal distortion. The question therefore is, how do their histories compare? Here we present the first reconstruction of the star formation histories of NGC 147 and NGC 185 using long-period variable stars. These represent the final phase of evolution of low- and intermediate-mass stars at the asymptotic giant branch, when their luminosity is related to their birth mass. Combining near-infrared photometry with stellar evolution models, we construct the mass function and hence the star formation history. For NGC 185 we found that the main epoch of star formation occurred 8.3 Gyr ago, followed by a much lower, but relatively constant star formation rate. In the case of NGC 147, the star formation rate peaked only 7 Gyr ago, staying intense until   3 Gyr ago, but no star formation has occurred for at least 300 Myr. Despite their similar masses, NGC 147 has evolved more slowly than NGC 185 initially, but more dramatically in more recent times. This is corroborated by the strong tidal distortions of NGC 147 and the presence of gas in the centre of NGC 185. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1612/1612.02588v1.pdf"}
{"id": "1701.07688", "abstract": "  We revisit the notion of nonclassical distance of states of bosonic quantum systems introduced in [M. Hillery, Phys. Rev. A 35, 725 (1987)] in a general multimode setting. After reviewing its definition, we establish some of its general properties. We obtain new upper and lower bounds on the nonclassical distance in terms of the supremum of the Husimi function of the state. Considering several examples, we elucidate the cases for which our lower bound is tight, which include the multimode number states and a class of multimode N00N states. The latter provide examples of states of definite photon number n ≥ 2 whose nonclassical distance can be made arbitrarily close to the upper limit of 1 by increasing the number of modes. We show that the nonclassical distance of the even and odd Schrödinger cat states is bounded away from unity regardless of how macroscopic the superpositions are, and that the nonclassical distance is not necessarily monotonically increasing with respect to macroscopicity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1701/1701.07688v2.pdf"}
{"id": "1702.06888", "abstract": "  Quantum erasers with paths in the form of physical slits have been studied extensively and proven instrumental in probing wave-particle duality in quantum mechanics. Here we replace physical paths (slits) with abstract paths of orbital angular momentum (OAM). Using spin-orbit hybrid entanglement of photons we show that the OAM content of a photon can be erased with a complimentary polarization projection of one of the entangled pair. The result is the (dis)appearance of azimuthal fringes based on whether the -OAM\" information was erased. We extend this concept to a delayed measurement scheme and show that the OAM information and fringe visibility are complimentary. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.06888v1.pdf"}
{"id": "1702.08375", "abstract": "  We compare the methods of amplitude reconstruction, for a complete experiment and a truncated partial-wave analysis, applied to the electroproduction of pseudoscalar mesons. We give examples which show, in detail, how the amplitude reconstruction (observables measured at a single energy and angle) is related to a truncated partial-wave analysis (observables measured at a single energy and a number of angles). A connection is made to existing data. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1702/1702.08375v1.pdf"}
{"id": "1703.00344", "abstract": "  Absolutely separable states ϱ remain separable under arbitrary unitary transformations U ϱ U^†. By example of a three qubit system we show that in multipartite scenario neither full separability implies bipartite absolute separability nor the reverse statement holds. The main goal of the paper is to analyze quantum maps resulting in absolutely separable output states. Such absolutely separating maps affect the states in a way, when no Hamiltonian dynamics can make them entangled afterwards. We study general properties of absolutely separating maps and channels with respect to bipartitions and multipartitions and show that absolutely separating maps are not necessarily entanglement breaking. We examine stability of absolutely separating maps under tensor product and show that Φ^⊗ N is absolutely separating for any N if and only if Φ is the tracing map. Particular results are obtained for families of local unital multiqubit channels, global generalized Pauli channels, and combination of identity, transposition, and tracing maps acting on states of arbitrary dimension. We also study the interplay between local and global noise components in absolutely separating bipartite depolarizing maps and discuss the input states with high resistance to absolute separability. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.00344v2.pdf"}
{"id": "1703.05742", "abstract": "  We have been developing optical resonant cavities for laser-Compton scattering experiment at the Accelerator Test Facility in KEK. The main subject of the R   D is to increase laser pulse energy by coherently accumulating the pulses in an optical resonant cavity. We report previous results, current status and future prospects, including a new idea of an optical resonant cavity. ", "pdf_url": "gs://arxiv-dataset/arxiv/arxiv/pdf/1703/1703.05742v1.pdf"}
{"id": "astro-ph0002435", "abstract": "  Two parameters are developed to analyze the CCD images from ground-based and/or space telescopes. The first parameter, deduced from the intensity profile of the object sharp, is useful to resolve stars and hot pixels. The second parameter shape distinguishes the stars from the background cosmic-ray events using geometric characteristics defined by its shapes. The parameters are applied to a simulated OMC/INTEGRAL image and a HST image. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0002/0002435v1.pdf"}
{"id": "astro-ph0004122", "abstract": "  Optical data in the V-band gathered with the 8.2m ESO Very Large Telescope (VLT) at the radio interferometric position of PSR 1706-44 are presented. The pulsar is close to a bright star in projection and was not detected. The pulsar magnitude limit must be fainter than V=24.5 for a distance of ≤ 20 from the bright star. In the outer gap model for an aligned rotor the optical flux should scale with the gamma-ray flux. For pulsars which emit pulsed gamma-rays but are not detected in the optical bands, the synchrotron cutoff frequency for the tertiary photons must be well below the optical frequencies and the magnetic and spin axes may be misaligned. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0004/0004122v1.pdf"}
{"id": "astro-ph0109352", "abstract": "  Nonlinear evolution of the gravitational radiation (GR) driven instability in the r-modes of neutron stars is studied by full numerical 3D hydrodynamical simulations. The growth of the r-mode instability is found to be limited by the formation of shocks and breaking waves when the dimensionless amplitude of the mode grows to about three in value. This maximum mode amplitude is shown by numerical tests to be rather insensitive to the strength of the GR driving force. Upper limits on the strengths of possible nonlinear mode–mode coupling are inferred. Previously unpublished details of the numerical techniques used are presented, and the results of numerous calibration runs are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0109/0109352v2.pdf"}
{"id": "astro-ph0205493", "abstract": "  We describe results from our initial study of the diffuse X-ray emission structures in NGC 5128 (Cen A) using the Chandra X-ray Observatory observations. The high-angular resolution Chandra images reveal multi-scale X-ray struct ures with unprecedented detail and clarity. The large scale structures suggest complex symmetry, including a component possibly associated with the inner radio lobes, and a separate component with an orthogonal symmetry that may be associated with the galaxy as a whole. We detect arc-like soft X-ray structures, extending to  8 kpc in the direction perpendicular to the jet. These arcs appear to be tracing an ellipse, or a ring seen in projection, and ar e enclosed between the dust and HI emitting gas in the central region of the galaxy, and the optical and HI shell fragments at a distance of about 8-10 kpc. The diffuse X-ray and the optical emission in the arcs could originate in a region of interaction (possibly a shock) between the infalling material from the outer regions of the galaxy, and the cool dust and HI emitting material in the center, or an equatorial outflow resulting from an outburst of nuclear activity  10^7 years ago. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0205/0205493v1.pdf"}
{"id": "astro-ph0209363", "abstract": "  We study correlations betwen X-ray spectral index, strength of Compton reflection, and X-ray and radio fluxes in accreting black holes (Seyferts and black-hole binaries). We critically evaluate the evidence for the correlation of the X-ray spectral index with the strength of Compton reflection and consider in detail statistical and systematic effects that can affect it. We study patterns of spectral variability (in particular, pivoting of a power law spectrum) corresponding to the X-ray index-flux correlation. We also consider implications of the form of observed X-ray spectra and their variability for interpretation of the correlation between the radio and X-ray fluxes. Finally, we discuss accretion geometries that can account for the correlations and their overall theoretical interpretations. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0209/0209363v3.pdf"}
{"id": "astro-ph0310030", "abstract": "  I summarize 40 years of development of the standard solar model that is used to predict solar neutrino fluxes and then describe the current uncertainties in the predictions. I will also attempt to explain why it took so long, about three and a half decades, to reach a consensus view that new physics is being learned from solar neutrino experiments. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0310/0310030v1.pdf"}
{"id": "astro-ph0310465", "abstract": "  This paper shows that a simple convolution integral expression based on the mean value of the isotropic frequency distribution corresponding to photon scattering off electrons leads to useful analytical expressions describing the thermal Sunyaev-Zel'dovich effect. The approach, to first order in the Compton parameter is able to reproduce the Kompaneets equation describing the effect. Second order effects in the parameter z=kT_e/mc^2 induce a slight increase in the crossover frequency. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0310/0310465v1.pdf"}
{"id": "astro-ph0403685", "abstract": "  More than half of all low-redshift AGN exhibit UV and X-ray absorption by highly ionized gas. The observed UV and X-ray absorption lines are almost always blue-shifted at velocities of hundreds of km/s, indicating that the absorbing gas is outflowing from the active nucleus. In some cases the inferred mass flux rivals the Eddington limit of the central black hole, an indication that these outflows are intimately related to the mass accretion and energy generation mechanism in AGN. The ejected material can also have an affect on the interstellar medium of the host galaxy and the surrounding intergalactic medium. Over the past several years, coordinated UV and X-ray observations of several bright AGN at high spectral resolution using HST, FUSE, Chandra, and XMM-Newton have contributed greatly to our understanding of these outflows. I will give an overview of these recent observations, summarize our FUSE survey of low-redshift AGN, and interpret the results in the context of models of winds from accretion disks and thermally driven winds from the obscuring torus. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0403/0403685v1.pdf"}
{"id": "astro-ph0404537", "abstract": "  The 2dF Galaxy Redshift Survey (2dFGRS) of 230,000 redshifts of nearby (z 0.1) galaxies is now complete. It has allowed the 2dFGRS team and others to estimate fundamental cosmological parameters and to study galaxy intrinsic properties. Here we highlight three recent key results from the survey: (i) an upper limit of about 2eV on the total mass of the three neutrino flavours, and an intriguing reasonable fitting of the 2dFGRS power spectrum to a Mixed Dark Matter model without a Cosmological Constant, but with a low Hubble constant; (ii) the bimodality of the galaxy population in both spectral parameterisation and in colour; and (iii) the clustering of different galaxy types and evidence for relative stochastic biasing. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0404/0404537v1.pdf"}
{"id": "astro-ph0407369", "abstract": "  We have reanalyzed the 260 ksec XMM-Newton observation of 1E1207.4-5209. There are several significant improvements over previous work. Firstly, a much broader range of physically plausible spectral models was used. Secondly, we have utilized a more rigorous statistical analysis. The standard F-distribution was not employed, but rather the exact finite statistics F-distribution was determined by Monte-Carlo simulations. This approach was motivated by the recent work of Protassov et al. (2002) and Freeman et al. (1999). They demonstrated that the standard F-distribution is not even asymptotically correct when applied to assess the signficance of additional absorption features in a spectrum. With our improved analysis we do not find a third and fourth spectral feature (Bignami et al. (2003), De Luca et al. (2004)) in 1E1207.4-5209, but only the two broad absorption features previously reported (Sanwal et al. (2002), Hailey and Mori (2002)). Two additional statistical tests, one line model dependent and the other line model independent confirmed our modified F-test analysis. For all physically plausible continuum models where the weak residuals are strong enough to fit, the residuals occur at the instrument Au-M edge. As a sanity check we confirmed that the residuals are consistent in strength and position with the instrument Au-M residuals observed in 3C273. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0407/0407369v2.pdf"}
{"id": "astro-ph0407590", "abstract": "  Interactions between galaxies are suggested to be a mechanism responsible for feeding Active Galactic Nuclei (AGN). Theoretical models show that interactions are an efficient way to drive gas from the galaxy to the nucleus, however, the observational evidence on this subject is controversial. Here we review results in this field, discuss possible limitations of previous studies and the importance of dealing with selection effects. We also show that there is no significant difference in the percentage of low luminosity AGN and normal galaxies with companions, and discuss possible interpretations of this result. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0407/0407590v1.pdf"}
{"id": "astro-ph0410435", "abstract": "  We present metallicities for 487 red giants in the Carina dwarf spheroidal (dSph) galaxy that were obtained from FLAMES low-resolution Ca triplet (CaT) spectroscopy. We find a mean [Fe/H] of -1.91 dex with an intrinsic dispersion of 0.25 dex, whereas the full spread in metallicities is at least one dex. The analysis of the radial distribution of metallicities reveals that an excess of metal poor stars resides in a region of larger axis distances. These results can constrain evolutionary models and are discussed in the context of chemical evolution in the Carina dSph. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0410/0410435v1.pdf"}
{"id": "astro-ph0411546", "abstract": "  We report the results of an extensive VLT high-resolution imaging campaign of the central region of the giant globular cluster omega Centauri. More than 100,000 stars have been measured in the inner 9'x 9' region of the cluster. On the basis of multiband Colour Magnitude Diagrams (CMD), we confirm the existence of multiple stellar populations along the Red Giant Branch (RGB). Moreover, thanks to the high-precision of this dataset, we conclude that the RGB does not present a smooth and continuous distribution, but shows a discrete structure: besides the metal-poor and the extreme metal-rich population (RGB-a), the existence of three metal intermediate populations is shown. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0411/0411546v1.pdf"}
{"id": "astro-ph0602575", "abstract": "  We analyze the Tully catalog of nearby galaxies to investigate the local pancaking effect on the orientation of disk galaxies. We first select only those edge-on disk galaxies in the catalog whose axis-ratios are less than 0.1 to measure their spin axes unambiguously. A local pancake at the location of each selected galaxy is found as a plane encompassing the two nearest neighbor disks. Then, we examine statistically the inclinations of the galaxy spin axes relative to the local pancake planes. It is detected that the Tully disk galaxies tend to be inclined onto the local pancake planes, and the average inclination angles decrease with the pancake scale. We also construct a theoretical model for the inclination of disk galaxies relative to the local pancakes in the frame of the linear tidal torque theory. The comparison of the theoretical prediction with the observational result demonstrates a good agreement. Finally, we conclude that it is a first detection of the local pancaking effect on the orientation of disk galaxies, which is consistent with the scenario that the gravitational tidal field promotes the formation of pancakes on small mass scale. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0602/0602575v1.pdf"}
{"id": "astro-ph0604425", "abstract": "  GRB 990413 shows a very hard spectrum (with a low energy spectral component F(E) ∝E^2.49) which is well represented by a black body model with characteristic temperature  70 keV. It thus belongs to the subset of GRBs which might be revealing a thermal phase. We find that the temperature/luminosity evolution is consistent with that found in the other “thermal” GRBs. The time resolved spectral analysis indicates the presence of a second non–thermal component contributing (for about 1 s) up to 30 per cent of the total flux. Differently from the other thermal GRBs, GRB 990413 shows significantly high level of variability and the evolution of the thermal/non–thermal spectral components is strongly correlated with the flux variations. This GRB thus offers the unique opportunity to test the standard fireball photospheric and internal shock phases and their reciprocal influence. GRB 990413 was not selected on the basis of its spectrum and thus hints to the possibility that this early behavior might be more common than currently known. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0604/0604425v1.pdf"}
{"id": "astro-ph0607541", "abstract": "  We have mapped the Helix (NGC 7293) planetary nebula (PN) with the IRAC instrument on the Spitzer Space Telescope. The Helix is one of the closest bright PN, and therefore provides an opportunity to resolve the small-scale structure in the nebula. The emission from this PN in the 5.8 and 8 micron IRAC bands is dominated by the pure rotational lines of molecular hydrogen, with a smaller contribution from forbidden line emission such as [Ar III] in the ionized region. The IRAC images resolve the \"cometary knots\" which have been previously studied in this PN. The \"tails\" of the knots and the radial rays extending into the outer regions of the PN are seen in emission in the IRAC bands. IRS spectra on the main ring and the emission in the IRAC bands are consistent with shock-excited H2 models, with a small ( 10", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0607/0607541v1.pdf"}
{"id": "astro-ph0607550", "abstract": "  Using adaptive optics at the Gemini North telescope we have obtained a K-band spectrum of the star near the center of the luminous Galactic center bowshock IRS8, as well as a spectrum of the bowshock itself. The stellar spectrum contains emission and absorption lines characteristic of an O5-O6 giant or supergiant. The wind from such a star is fully capable of producing the observed bowshock. However, both the early spectral type and the apparently young age of the star, if it is single, mark it as unique among hot stars within one parsec of the center. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0607/0607550v1.pdf"}
{"id": "astro-ph0608704", "abstract": "  We have obtained high resolution (R = 10,000) K-band spectra of candidate young massive stars deeply embedded in high-mass star-forming regions. These objects were selected from a near-infrared survey of 44 regions of high-mass star-formation (Kaper et al, 2006). In these clusters, 38 OB stars are identified whose K-band spectra are dominated by photospheric emission. In almost all those stars, the K-band spectra are indistinguishable from field stars. However, in some stars the profile of the Bracket gamma line is different (less deep, or absent) from those of the O field stars. One of the explanations of these profiles might be an enhanced mass-loss. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0608/0608704v1.pdf"}
{"id": "astro-ph0612519", "abstract": "  We present the polarization images in the J, H,     Ks bands of the Orion Molecular Cloud 1 South region. The polarization images clearly show at least six infrared reflection nebulae (IRNe) which are barely seen or invisible in the intensity images. Our polarization vector images also identify the illuminating sources of the nebulae: IRN 1     2, IRN 3, 4,     5, and IRN 6 are illuminated by three IR sources, Source 144-351, Source 145-356, and Source 136-355, respectively. Moreover, our polarization images suggest the candidate driving sources of the optical Herbig-Haro objects for the first time; HH529, a pair of HH202 and HH528 or HH 203/204, HH 530 and HH269 are originated from Source 144-351, Source 145-356, and Source 136-355, respectively. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0612/0612519v1.pdf"}
{"id": "astro-ph0612716", "abstract": "  We present additional tests of our algorithm aimed at filtering out systematics due to data reduction and instrumental imperfections in time series obtained by ensemble photometry. Signal detection efficiency is demonstrated, and a method of decreasing the false alarm probability is presented. Including the recently discovered transiting extrasolar planet HAT-P-1, we show various examples on the signal reconstruction capability of the method. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/0612/0612716v1.pdf"}
{"id": "astro-ph9705256", "abstract": "  We describe how thermally produced anti-electron neutrinos (ν̅_e) from the homologously collapsing core of a supermassive star (M  5×10^4 M_⊙) can lead to significant deuterium enrichment in the ejected envelope of such a star. Deuterium-enriched material at high redshift might then serve as a clue to the existence of pregalactic supermassive stars. Conceivably, the ejected deuterium-enriched material could intercept the line of sight to a distant QSO and mimic a Lyman limit absorber. In such a case, the deuterium abundance inferred from absorption lines might not reflect the true primordial abundance of deuterium. We discuss relevant theoretical uncertainties in supermassive star physics as well as potential observational signatures in Lyman α absorber clouds for processing by stars of this kind. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9705/9705256v2.pdf"}
{"id": "astro-ph9707096", "abstract": "  We present the results from RXTE observations of a new X-ray transient, GRS 1737-31, near the Galactic center during an outburst. Over a span of two weeks, the source was seen to vary significantly on time scales down to a few seconds. The rapid flares in the light curves bear resemblance to those observed for Cygnus X-1, a well-known black hole candidate (BHC). The power-density spectrum is also very typical of BHCs in the HARD (or LOW) state: it is flat below a characteristic break frequency of  0.03 Hz, and becomes roughly a 1/f power law above. The observed X-ray spectrum can be characterized by a simple power law with a photon index of  1.7 over a broad energy range 2-200 keV, which is remarkably similar to that of Cyg X-1 in the HARD state. The similarities to Cyg X-1 make GRS 1737-31 a likely BHC. However, unlike most transient BHCs, GRS 1737-31 does not seem to reach a “soft state” even during an outburst. We discuss this phenomenon in light of the comparison to a class of hard X–ray BHCs including transients GRO J0422+32, V404Cyg and GRO J1719-24, and persistent sources 1E1740.7-2942 and GRS 1758-258. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9707/9707096v1.pdf"}
{"id": "astro-ph9707343", "abstract": "  The best measured rotation curve for any galaxy is that of the dwarf spiralXXXX DDO 154, which extends out to about 20 disk scale lengths. It provides an ideal laboratory for testing the universal density profile prediction from high resolution numerical simulations of hierarchical clustering in cold dark matter dominated cosmological models. We find that the observed rotation curve cannot be fit either at small radii, as previously noted, or at large radii. We advocate a resolution of this dilemma by postulating the existence of a dark spheroid of baryons amounting to several times the mass of the observed disk component and comparable to that of the cold dark matter halo component. Such an additional mass component provides an excellent fit to the rotation curve provided that the outer halo is still cold dark matter-dominated with a density profile and mass-radius scaling relation as predicted by standard CDM-dominated models. The universal existence of such dark baryonic spheroidal components provides a natural explanation of the universal rotation curves observed in spiral galaxies, may have a similar origin and composition to the local counterpart that has been detected as MACHOs in our own galactic halo via gravitational microlensing, and is consistent with, and even motivated by, primordial nucleosynthesis estimates of the baryon fraction. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9707/9707343v1.pdf"}
{"id": "astro-ph9712022", "abstract": "  A single merger scenario for making galaxies such as NGC 4550 possessing equal coplanar counter-rotating stellar disks is investigated by collisionless N-body technique. The scenario is successful in producing an axisymmetric disk made of two almost equal counter-rotating populations. The final disk shows a clear bimodal line profile in the outer part, which demonstrates that disk-disk mergers do not always produce ellipticals. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9712/9712022v1.pdf"}
{"id": "astro-ph9802069", "abstract": "  The high spatial resolution of the MECS experiment on board Beppo-SAX has encouraged a few scientists, including the author, to perform observations of galaxy clusters. Results from the analysis of the first few observed objects are encouraging. After having reviewed the Beppo-SAX observing program for galaxy clusters and referenced contributions to these proceedings by other authors on the same topic, I present results from the analysis of the Perseus cluster. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9802/9802069v1.pdf"}
{"id": "astro-ph9811204", "abstract": "  The satellite-disk interaction provides limits on halo properties in two ways: (1) physical arguments motivate the excitation of observable Galactic disk structure in the presence of a massive halo, although precise limits on halo parameters are scenario-dependent; (2) conversely, the Milky Way as a whole has significant dynamical effect on LMC structure and this interaction also leads to halo limits. Together, these scenarios give strong corroboration of our current gravitational mass estimates and suggests a rapidly evolving LMC. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9811/9811204v1.pdf"}
{"id": "astro-ph9901066", "abstract": "  We deduce the equations that describe how polarized radiation is Comptonized by a hot electron gas. Low frequencies are considered, and the equations are expanded to second order in electron velocities. Induced scattering terms are included and a Maxwellian velocity distribution for the electrons is assumed. The special case of an axisymmetric radiation field is also considered, and the corresponding radiative transfer equations are found. Our results correct errors and misprints in previosly published transfer equations. The extension to a moving electron gas is made, and the radiative transfer equations are deduced to second order in gas velocity. We use the equations to study polarization in the Sunyaev-Zeldovich effect. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9901/9901066v1.pdf"}
{"id": "astro-ph9901397", "abstract": "  I collect emission line profiles for seven intermediate polars, phase-resolved over the spin cycles. I then present the first systematic application of Doppler tomography to the spin cycles, with the aim of investigating whether spin-cycle tomography is a useful diagnostic tool. Four stars show line emission from material falling onto both magnetic poles of the white dwarf, but three others show line emission from only the upper pole. Tomography can map the extent and shape of the line-emitting accretion curtains, but it can also give misleading results if the line flux changes significantly over the spin cycle. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9901/9901397v1.pdf"}
{"id": "astro-ph9904121", "abstract": "  When density fluctuations collapse gravitationally out of the expanding cosmological background universe to form galaxies, the secondary energy release which results can affect their subsequent evolution profoundly. We focus here on the effects of one form of such energy release - explosions, such as might result from the supernovae which end the lives of the first generation of massive stars to form inside protogalaxies. We are particularly interested in the consequences of the nonspherical geometry and continuous infall which are characteristic of galaxy formation from realistic initial and boundary conditions. As an idealized model which serves to illustrate and quantify the importance of these effects, we study the effect of explosions on the quasi-spherical objects which form at the intersections of filaments in the plane of a cosmological pancake, as a result of gravitational instability and fragmentation of the pancake. We study the formation and evolution of these \"galaxies,\" subject to the explosive injection of energy at their centers, by numerical gas dynamical simulation in 3D utilizing our new, anisotropic version of Smoothed Particle Hydrodynamics, Adaptive SPH (\"ASPH\"), with a P3M gravity solver. ", "pdf_url": "gs://arxiv-dataset/arxiv/astro-ph/pdf/9904/9904121v1.pdf"}
{"id": "cmp-lg9405031", "abstract": "  This paper provides a model theoretic semantics to feature terms augmented with set descriptions. We provide constraints to specify HPSG style set descriptions, fixed cardinality set descriptions, set-membership constraints, restricted universal role quantifications, set union, intersection, subset and disjointness. A sound, complete and terminating consistency checking procedure is provided to determine the consistency of any given term in the logic. It is shown that determining consistency of terms is a NP-complete problem. ", "pdf_url": "gs://arxiv-dataset/arxiv/cmp-lg/pdf/9405/9405031v1.pdf"}
{"id": "cond-mat0101155", "abstract": "  Quasiparticle states around a single vortex in a p_x± i p_y-wave superconductor are studied on the basis of the Bogoliubov-de Gennes (BdG) theory, where both charge and current screenings are taken into account. Due to the violation of time reversal symmetry, there are two types of vortices which are distinguished by their winding orientations relative to the angular momentum of the chiral Cooper pair. The BdG solution shows that the charges of the two types of vortices are quite different, reflecting the rotating Cooper pair of the p_x± i p_y-wave paring state. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0101/0101155v2.pdf"}
{"id": "cond-mat0101229", "abstract": "  Drug resistance to HIV-1 Protease involves accumulation of multiple mutations in the protein. Here we investigate the role of these mutations by using molecular dynamics simulations which exploit the influence of the native-state topology in the folding process. Our calculations show that sites contributing to phenotypic resistance of FDA-approved drugs are among the most sensitive positions for the stability of partially folded states and should play a relevant role in the folding process. Furthermore, associations between amino acid sites mutating under drug treatment are shown to be statistically correlated. The striking correlation between clinical data and our calculations suggest a novel approach to the design of drugs tailored to bind regions crucial not only for protein function but also for folding. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0101/0101229v1.pdf"}
{"id": "cond-mat0109315", "abstract": "  An Ornstein-Zernike approximation for the two-body correlation function embodying thermodynamic consistency is applied to a system of classical Heisenberg spins on a three-dimensional lattice. The consistency condition determined in a previous work is supplemented by introducing a simplified expression for the mean-square fluctuations of the spin on each lattice site. The thermodynamics and the correlations obtained by this closure are then compared with approximants based on extrapolation of series expansions and with Monte Carlo simulations. The comparison reveals that many properties of the model, including the critical temperature, are very well reproduced by this simple version of the theory, but that it shows substantial quantitative error in the critical region, both above the critical temperature and with respect to its rendering of the spontaneous magnetization curve. A less simple but conceptually more satisfactory version of the SCOZA is then developed, but not solved, in which the effects of transverse correlations on the longitudinal susceptibility is included, yielding a more complete and accurate description of the spin-wave properties of the model. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0109/0109315v1.pdf"}
{"id": "cond-mat0112117", "abstract": "  We present a 2-dimensional cellular automaton model for the simulation of pedestrian dynamics. The model is extremely efficient and allows simulations of large crowds faster than real time since it includes only nearest-neighbour interactions. Nevertheless it is able to reproduce collective effects and self-organization encountered in pedestrian dynamics. This is achieved by introducing a so-called floor field which mediates the long-range interactions between the pedestrians. This field modifies the transition rates to neighbouring cells. It has its own dynamics (diffusion and decay) and can be changed by the motion of the pedestrians. Therefore the model uses an idea similar to chemotaxis, but with pedestrians following a virtual rather than a chemical trace. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0112/0112117v1.pdf"}
{"id": "cond-mat0301539", "abstract": "  In this paper we solve one dimensional SU(3) bosons with repulsive δ-function interaction by means of Bethe ansatz method. The features of ground state and low-lying excited states are studied by both numerical and analytic methods. We show that the ground state is a SU(3) color ferromagnetic state. The configurations of quantum numbers for the ground state are given explicitly. For finite N system the spectra of low-lying excitations and the dispersion relations of four possible elementary particles (holon, antiholon, σ-coloron and ω-coloron) are obtained by solving Bethe-ansatz equation numerically. The thermodynamic equilibrium of the system at finite temperature is studied by using the strategy of thermodynamic Bethe ansatz, a revised Gaudin-Takahashi equation which is useful for numerical method are given . The thermodynamic quantities, such as specific heat, are obtain for some special cases. We find that the magnetic property of the model in high temperature regime is dominated by Curie's law: χ∝ 1/T and the system has Fermi-liquid like specific heat in the strong coupling limit at low temperature. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0301/0301539v1.pdf"}
{"id": "cond-mat0402457", "abstract": "  We compute the finite-temperature single-particle spectral function of a one-dimensional Luttinger liquid coupled to an optical phonon band. The calculation is performed exactly for the case in which electron-phonon coupling is purely forward scattering. We extend the results to include backward scattering with a renormalization group treatment. The dispersion contains a change in velocity at the phonon energy, qualitatively similar to the case of electron-phonon coupling in a Fermi liquid. If the backward scattering part of the the electron-phonon interaction is not too strong compared to the forward scattering part, coupling to phonons also produces a pronounced peak in the spectral function at low energies. The calculated spectral function is remarkably similar to the angle-resolved photoemission spectra of the high-temperature superconductors, including the apparent presence of \"nodal quasiparticles,\" the presence of a \"kink\" in the dispersion, and the non-Fermi-liquid frequency and temperature dependencies. Although a microscopic justification has not been established for treating the electronic dynamics of the cuprates as quasi-one-dimensional, at the very least we take the quality of the comparison as evidence of the non-Fermi-liquid character of the measured spectra. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0402/0402457v5.pdf"}
{"id": "cond-mat0403433", "abstract": "  In the present paper we introduce generalized kinetic equations describing the dynamics of a system of interacting gas and photons obeying to a very general statistics. In the space homogeneous case we study the equilibrium state of the system and investigate its stability by means of Lyapounov's theory. Two physically relevant situations are discussed in details: photons in a background gas and atoms in a background radiation. After having dropped the statistics generalization for atoms but keeping the statistics generalization for photons, in the zero order Chapmann-Enskog approximation, we present two numerical simulations where the system, initially at equilibrium, is perturbed by an external isotropic Dirac's delta and by a constant source of photons. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0403/0403433v1.pdf"}
{"id": "cond-mat0404543", "abstract": "  A first-principles theory of resonant magnetic scattering of x rays is presented. The scattering amplitudes are calculated using a standard time-dependent perturbation theory to second order in the electron-photon interaction vertex. In order to calculate the cross section reliably an accurate description of the electronic states in the material under investigation is required and this is provided by the density functional theory (DFT) employing the Local Spin Density Approximation combined with the self-interaction corrections (SIC-LSD). The magnetic x-ray resonant scattering (MXRS) theory has been implemented in the framework of the relativistic spin-polarized LMTO-ASA band structure calculation method. The theory is illustrated with an application to ferromagnetic praseodymium. It is shown that the theory quantitatively reproduces the dependence on the spin and orbital magnetic moments originally predicted qualitatively (Blume, J. Appl. Phys, 57, 3615 (1985)) and yields results that can be compared directly with experiment. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0404/0404543v3.pdf"}
{"id": "cond-mat0410139", "abstract": "  In magnetic fields applied within the angular range of the surface superconductivity state a magnetically anisotropic layered medium is created in structurally isotropic, sufficiently thick niobium films. Surface (Kulik) vortices residing in the superconducting sheaths on both main film surfaces in tilted fields are shown to undergo a decoupling transition from a coherent to an independent behavior, similar to the behavior observed for Giaever transformer. At the transition a feature in pinning properties is measured, which implies different pinning for the lattice of surface vortices coherently coupled through the normal layer and for two decoupled vortex arrays in the superconducting surface sheaths. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0410/0410139v1.pdf"}
{"id": "cond-mat0508119", "abstract": "  ARPES spectra hold a wealth of information about the many-body interactions in a correlated material. However, the quantitative analysis of ARPES spectra to extract the various coupling parameters in a consistent manner is extremely challenging, even for a model Fermi liquid system. We propose a fitting procedure which allows quantitative access to the intrinsic lineshape, deconvolved of energy and momentum resolution effects, of the correlated 2-dimensional material Sr2RuO4. For the first time in correlated 2-dimensional materials, we find an ARPES linewidth that is narrower than its binding energy, a key property of quasiparticles within Fermi liquid theory. We also find that when the electron-electron scattering component is separated from the electron-phonon and impurity scattering terms it decreases with a functional form compatible with Fermi liquid theory as the Fermi energy is approached. In combination with the previously determined Fermi surface, these results give the first complete picture of a Fermi liquid system via ARPES. Furthermore, we show that the magnitude of the extracted imaginary part of the self-energy is in remarkable agreement with DC transport measurements. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0508/0508119v1.pdf"}
{"id": "cond-mat0602482", "abstract": "  In the case of a two-leg Hubbard ladder we present a procedure which allows the exact deduction of the ground state for the four particle problem in arbitrary large lattice system, in a tractable manner, which involves only a reduced Hilbert space region containing the ground state. In the presented case, the method leads to nine analytic, linear, and coupled equations providing the ground state. The procedure which is applicable to few particle problems and other systems as well is based on an r-space representation of the wave functions and construction of symmetry adapted orthogonal basis wave vectors describing the Hilbert space region containing the ground state. Once the ground state is deduced, a complete quantum mechanical characterization of the studied state can be given. Since the analytic structure of the ground state becomes visible during the use of the method, its importance is not reduced only to the understanding of theoretical aspects connected to exact descriptions or potential numerical approximation scheme developments, but is relevant as well for a large number of potential technological application possibilities placed between nano-devices and quantum calculations, where the few particle behavior and deep understanding are important key aspects to know. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0602/0602482v1.pdf"}
{"id": "cond-mat0609706", "abstract": "  We establish that the ability of a localized trapping potential to bind weakly-interacting bosons is dramatically enhanced in the vicinity of the threshold of formation of the single-particle bound-state of the trap. Specifically, for repulsive particles and a super-threshold trapping potential the equilibrium number of bound bosons and the size of the ground state diverge upon approaching the single-particle threshold from above. For attractive interactions and a sub-threshold trap a collective bound state always forms for a sufficiently large number of bosons despite the inability of interparticle attraction alone to form a two-body bound state. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/0609/0609706v2.pdf"}
{"id": "cond-mat9607025", "abstract": "  We study the classical two-dimensional Coulomb gas model for thermal vortex fluctuations in thin superconducting/superfluid films by Monte Carlo simulation of a grand canonical vortex ensemble defined on a continuum. The Kosterlitz-Thouless transition is well understood at low vortex density, but at high vortex density the nature of the phase diagram and of the vortex phase transition is less clear. From our Monte Carlo data we construct phase diagrams for the 2D Coulomb gas without any restrictions on the vortex density. For negative vortex chemical potential (positive vortex core energy) we always find a Kosterlitz-Thouless transition. Only if the Coulomb interaction is supplemented with a short-distance repulsion, a first order transition line is found, above some positive value of the vortex chemical potential. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9607/9607025v1.pdf"}
{"id": "cond-mat9611229", "abstract": "  We introduce a new class of models in which a large number of \"agents\" organize under the influence of an externally imposed coherent noise. The model shows reorganization events whose size distribution closely follows a power law over many decades, even in the case where the agents do not interact with each other. In addition the system displays \"aftershock\" events in which large disturbances are followed by a string of others at times which are distributed according to a 1/t law. We also find that the lifetimes of the agents in the system possess a power-law distribution. We explain all of these results using an approximate analytic treatment of the dynamics and discuss a number of variations on the basic model relevant to the study of particular physical systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/cond-mat/pdf/9611/9611229v1.pdf"}
{"id": "gr-qc0012092", "abstract": "  New techniques to evaluate the clock effect using light are described. These are based on the flatness of the cylindrical surface containing the world lines of the rays constrained to move on circular trajectories about a spinning mass. The effect of the angular momentum of the source is manifested in the fact that inertial observers must be replaced by local non rotating observers. Starting from this an exact formula for circular trajectories is found. Numerical estimates for the Earth environment show that light would be a better probe than actual clocks to evidence the angular momentum influence. The advantages of light in connection with some principle experiments are shortly reviewed. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0012/0012092v1.pdf"}
{"id": "gr-qc0405070", "abstract": "  The conversion of the read-out from the anti-symmetric port of the LIGO interferometers into gravitational strain has thus far been performed in the frequency domain. Here we describe a conversion in the time domain which is based on the method developed by GEO. We illustrate the method using the Hanford 4km interferometer during the second LIGO science run (S2). ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0405/0405070v1.pdf"}
{"id": "gr-qc0505109", "abstract": "  The causal interpretation of quantum mechanics is applied to a homogeneous and isotropic quantum universe, whose matter content is composed by non interacting dust and radiation. For wave functions which are eigenstates of the total dust mass operator, we find some bouncing quantum universes which reachs the classical limit for scale factors much larger than its minimum size. However these wave functions do not have unitary evolution. For wave functions which are not eigenstates of the dust total mass operator but do have unitary evolution, we show that, for flat spatial sections, matter can be created as a quantum effect in such a way that the universe can undergo a transition from an exotic matter dominated era to a matter dominated one. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0505/0505109v1.pdf"}
{"id": "gr-qc0702146", "abstract": "  Extreme-mass-ratio inspirals (EMRIs) and intermediate-mass-ratio inspirals (IMRIs)–binaries in which a stellar-mass object spirals into a massive black hole or other massive, compact body–are important sources of gravitational waves for LISA and LIGO, respectively. Thorne has speculated that the waves from EMRIs and IMRIs encode, in principle, all the details of (i) the central body's spacetime geometry (metric), (ii) the tidal coupling (energy and angular momentum exchange) between the central body and orbiting object, and (iii) the evolving orbital elements. Fintan Ryan has given a first partial proof that this speculation is correct: Restricting himself to nearly circular, nearly equatorial orbits and ignoring tidal coupling, Ryan proved that the central body's metric is encoded in the waves. In this paper we generalize Ryan's theorem. Retaining Ryan's restriction to nearly circular and nearly equatorial orbits, and dropping the assumption of no tidal coupling, we prove that Thorne's conjecture is nearly fully correct: the waves encode not only the central body's metric but also the evolving orbital elements and (in a sense slightly different from Thorne's conjecture) the evolving tidal coupling. ", "pdf_url": "gs://arxiv-dataset/arxiv/gr-qc/pdf/0702/0702146v1.pdf"}
{"id": "hep-ex0007048", "abstract": "  We propose using a Bayes procedure with uniform improper prior to determine credible belts for the mean of a Poisson distribution in the presence of background and for the continuous problem of measuring a non-negative quantity θ with a normally distributed measurement error. Within the Bayesian framework, these belts are optimal. The credible limits are then examined from a frequentist point of view and found to have good frequentist and conditional frequentist properties. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ex/pdf/0007/0007048v2.pdf"}
{"id": "hep-ex0212041", "abstract": "  A 4600 Hz fast ramping synchrotron is explored as an economical way of accelerating muons from 4 to 20 GeV/c for a neutrino factory. Eddy current losses are minimized by the low machine duty cycle plus thin grain oriented silicon steel laminations and thin copper wires. Combined function magnets with high gradients alternating within single magnets form the lattice we describe. Muon survival is 83", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ex/pdf/0212/0212041v1.pdf"}
{"id": "hep-lat0603028", "abstract": "  We present data for the axial coupling constant g_A of the nucleon obtained in lattice QCD with two degenerate flavours of dynamical non-perturbatively improved Wilson quarks. The renormalisation is also performed non-perturbatively. For the analysis we give a chiral extrapolation formula for g_A based on the small scale expansion scheme of chiral effective field theory for two degenerate quark flavours. Applying this formalism in a finite volume we derive a formula that allows us to extrapolate our data simultaneously to the infinite volume and to the chiral limit. Using the additional lattice data in finite volume we are able to determine the axial coupling of the nucleon in the chiral limit without imposing the known value at the physical point. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-lat/pdf/0603/0603028v2.pdf"}
{"id": "hep-ph0105224", "abstract": "  We quantify the rate and the signal-to-background ratio for Higgs –> b anti-b detection in double-diffractive events at the Tevatron and the LHC. The signal is predicted to be very small at the Tevatron, but observable at the LHC. We show that the double-diffractive dijet production may serve as a unique gluon factory. This process can be used also as a Pomeron-Pomeron luminosity monitor. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0105/0105224v1.pdf"}
{"id": "hep-ph0301263", "abstract": "  The heavy quark production in ultraperipheral heavy ion collisions is investigated, in particular we focus on the results from the coherent interactions given by the two-photon process. One addresses the heavy quark total cross sections at photon level considering the saturation model and the BFKL dynamics in the color dipole picture. The corresponding cross sections at nuclear level are presented. It is verified that the QCD dynamics implies an enhancement of the cross section in comparison with previous calculations. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0301/0301263v2.pdf"}
{"id": "hep-ph0302076", "abstract": "  The precise measurements of the “electroweak observables” performed at LEP and SLC are well consistent with the standard model predictions. Deviations from the standard model arising from vacuum polarization diagrams (also called “weak loop corrections”) have been constrained in a model-independent manner with the epsilon formalism. Within the same formalism, additional deviations from new physics production processes can also be constrained, still in a model-independent way. For instance, a 95", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0302/0302076v3.pdf"}
{"id": "hep-ph0504097", "abstract": "  The low-lying spectrum of the quark model is shown to be robust under the effects of `unquenching'. In contrast, the use of screened potentials is shown to be of limited use in models of hadrons. Applications to unquenching the lattice Wilson loop potential and to glueball mixing in the adiabatic hybrid spectrum are also presented. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0504/0504097v2.pdf"}
{"id": "hep-ph0609147", "abstract": "  In this talk we analyse the claim that supersymmetry (SUSY) naturally accounts for the observed dark matter density. In many cases, it is necessary to tune the parameters of a SUSY model to fit the WMAP data. We provide a quantitative analysis of the degree of tuning required for different annihilation channels. Some regions are natural, requiring no tuning at all, whereas others require tuning at the 0.1", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0609/0609147v2.pdf"}
{"id": "hep-ph0701154", "abstract": "  Hard partons propagating through hot and dense matter lose energy, leading to the observed depletion of hard hadron spectra in nucleus nucleus collision as compared to scaled proton proton collisions. This lost energy has to be redistributed in the medium due to the conservation of energy, which is manifest in the p_T dependence of the angular correlation pattern of hadrons associate with a (semi-) hard trigger. While at low p_T a splitting of a broad peak is observed, at high p_T the structure shows vacuum width, albeit with reduced yield. This sugests a transfer of energy from hard partons to a collectively recoiling medium. We present a systematic study of these phenomena using a realistic medium evolution and a Monte-Carlo simulation of the experimental trigger and show what information about the medium can be derived from multiparticle correlations. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/0701/0701154v1.pdf"}
{"id": "hep-ph9404252", "abstract": "  High energy particles are produced by the annihilation of dark matter particles in our galaxy. These are presently searched for using balloon-borne antiproton and positron detectors and large area, deep underground neutrino telescopes. Dark matter particles, trapped inside the sun, are an abundant source of such neutrinos.   From both the cosmological and particle physics points of view the lightest, stable supersymmetric particle or neutralino is arguably the leading dark matter candidate. Its mass is bracketed by a minimum value of order a few tens of GeV, determined from unsuccessful accelerator searches, and a maximum value of order 1 TeV imposed by particle physics as well as cosmological constraints. Back-of-the-envelope calculations are sufficient to demonstrate how present neutrino telescopes are competitive with existing and future particle colliders such as the LHC in the search for supersymmetry. We emphasize that a 1  km^2 area is the natural scale for a future instrument capable of probing the full GeV–TeV neutralino mass range by searching for high energy neutrinos produced by their annihilation in the sun. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9404/9404252v1.pdf"}
{"id": "hep-ph9807306", "abstract": "  The existing measurements of the solar neutrino flux are compared with the predictions of all models capable of reproducing the other solar observables. These predictions are supplemented by the hypothesis of neutrino oscillations with mass differences large enough to render energy-independent the depletion of the solar nu(e) flux. It is concluded that the data are consistent with this hypothesis and that an energy-dependence of the solar neutrino deficit must be regarded as an attractive possibility but not as a compelling reality. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-ph/pdf/9807/9807306v1.pdf"}
{"id": "hep-th0201070", "abstract": "  We study the quantum mechanics of a charged particle on a constant curvature noncommutative Riemann surface in the presence of a constant magnetic field. We formulate the problem by considering quantum mechanics on the noncommutative AdS_2 covering space and gauging a discrete symmetry group which defines a genus-g surface. Although there is no magnetic field quantization on the covering space, a quantization condition is required in order to have single-valued states on the Riemann surface. For noncommutative AdS_2 and subcritical values of the magnetic field the spectrum has a discrete Landau level part as well as a continuum, while for overcritical values we obtain a purely noncommutative phase consisting entirely of Landau levels. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0201/0201070v2.pdf"}
{"id": "hep-th0207043", "abstract": "  We have studied a modified Yang-Mills-Higgs system coupled to Einstein gravity. The modification of the Einstein-Hilbert action involves a direct coupling of the Higgs field to the scalar curvature. In this modified system we are able to write a Bogomol'nyi type condition in curved space and demonstrate that the positive static energy functional is bounded from below. We then investigate non-Abelian sperically symmetric static solutions in a similar fashion to the `t Hooft-Polyakov monopole. After reviewing previously studied monopole solutions of this type, we extend the formalism to included electric charge and we present dyon solutions. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0207/0207043v1.pdf"}
{"id": "hep-th0211096", "abstract": "  We show that the rigidly rotating quantum thermal distribution on flat space-time suffers from a global pathology which can be cured by introducing a cylindrical mirror if and only if it has a radius smaller than that of the speed-of-light cylinder. When this condition is met, we demonstrate numerically that the renormalized expectation value of the energy-momentum stress tensor corresponds to a rigidly rotating thermal bath up to a finite correction except on the mirror where there are the usual Casimir divergences. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0211/0211096v2.pdf"}
{"id": "hep-th0310114", "abstract": "  Renormalization-group (RG) flow equations have been derived for the generalized sine-Gordon model (GSGM) and the Coulomb gas (CG) in d >= 3 of dimensions by means of Wegner's and Houghton's, and by way of the real-space RG approaches. The UV scaling laws determined by the leading-order terms of the flow equations are in qualitative agreement for all dimensions d >= 3, independent of the dimensionality, and in sharp contrast to the special case d = 2. For the 4-dimensional GSGM it is demonstrated explicitly (by numerical calculations), that the blocked potential tends to a constant effective potential in the infrared (IR) limit, satisfying the requirements of periodicity and convexity. The comparison of the RG flows for the three-dimensional GSGM, the CG, and the vortex-loop gas reveals a significant dependence on the renormalization schemes and the approximations used. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0310/0310114v1.pdf"}
{"id": "hep-th0504088", "abstract": "  We give a formal proof that the space-time average of the vacuum condensate of mass dimension two, i.e., the vacuum expectation value of the squared potential 𝒜_μ^2, is gauge invariant in the weak sense that it is independent of the gauge-fixing condition adopted in quantizing the Yang-Mills theory. This is shown at least for the small deformation from the generalized Lorentz and the modified Maximal Abelian gauge in the naive continuum formulation neglecting Gribov copies. This suggests that the numerical value of the condensate could be the same no matter what gauge-fixing conditions for choosing the representative from the gauge orbit are adopted to measure it. Finally, we discuss how this argument should be modified when the Gribov copies exist. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/0504/0504088v2.pdf"}
{"id": "hep-th9404151", "abstract": "  The moduli space of N=(4,4) string theories with a K3 target space is determined, establishing in particular that the discrete symmetry group is the full integral orthogonal group of an even unimodular lattice of signature (4,20). The method combines an analysis of the classical theory of K3 moduli spaces with mirror symmetry. A description of the moduli space is also presented from the viewpoint of quantum geometry, and consequences are drawn concerning mirror symmetry for algebraic K3 surfaces. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/9404/9404151v1.pdf"}
{"id": "hep-th9511223", "abstract": "  We construct two classes of higher-derivative supergravity theories generalizing Einstein supergravity. We explore their dynamical content as well as their vacuum structure. The first class is found to be equivalent to Einstein supergravity coupled to a single chiral superfield. It has a unique stable vacuum solution except in a special case, when it becomes identical to a simple no-scale theory. The second class is found to be equivalent to Einstein supergravity coupled to two chiral superfields and has a richer vacuum structure. It is demonstrated that theories of the second class can possess a stable vacuum with vanishing cosmological constant that spontaneously breaks supersymmetry. We present an explicit example of this phenomenon and compare the result with the Polonyi model. ", "pdf_url": "gs://arxiv-dataset/arxiv/hep-th/pdf/9511/9511223v2.pdf"}
{"id": "math-ph9808008", "abstract": "  We present a novel method to estimate the stability of the Marchenko equation for finite data-sets. We show that we can derive a recursion relationship for the Fourier expansion coefficients of the kernel which is solved by the Marchenko equation. The method can easily be implemented numerically. Moreover, we discus the stability of the one-dimensional inverse scattering problem by using Lyapunov exponents. We give conditions on the scattering data to provide stable inversion results. A numerical example is given. ", "pdf_url": "gs://arxiv-dataset/arxiv/math-ph/pdf/9808/9808008v2.pdf"}
{"id": "math0102094", "abstract": "  The recently introduced backward Monte-Carlo method [Johan Carlsson, arXiv:math.NA/0010118] is validated, benchmarked, and compared to the conventional, forward Monte-Carlo method by analyzing the error in the Monte-Carlo solutions to a simple model equation. In particular, it is shown how the backward method reduces the statistical error in the common case where the solution is of interest in only a small part of phase space. The forward method requires binning of particles, and linear interpolation between the bins introduces an additional error. Reducing this error by decreasing the bin size increases the statistical error. The backward method is not afflicted by this conflict. Finally, it is shown how the poor time convergence can be improved for the backward method by a minor modification of the Monte-Carlo equation of motion that governs the stochastic particle trajectories. This scheme does not work for the conventional, forward method. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0102/0102094v1.pdf"}
{"id": "math0212309", "abstract": "  We give an elementary introduction to some recent polyhedral techniques for understanding and solving systems of multivariate polynomial equations. We provide numerous concrete examples and illustrations, and assume no background in algebraic geometry or convex geometry. Highlights include the following:   (1) A completely self-contained proof of an extension of Bernstein's Theorem. Our extension relates volumes of polytopes with the number of connected components of the complex zero set of a polynomial system, and allows any number of polynomials and/or variables.   (2) A near optimal complexity bound for computing mixed area – a quantity intimately related to counting complex roots in the plane. ", "pdf_url": "gs://arxiv-dataset/arxiv/math/pdf/0212/0212309v1.pdf"}
{"id": "nucl-ex0011003", "abstract": "  Today, we have a variety of reactions at hand that can be used to multi-fragment nuclei. In many of these reactions even several sources of fragments can be discerned and characterized.   There is overwhelming evidence that these sources of fragments are hot. It is already less clear whether heat by itself is sufficient to initiate the fragment decay. What causes fragmentation, and when and how are the fragments (pre)formed? These questions have remained as much a challenge as the complementary class of questions to which they are related: What observations derive their significance from the liquid-gas phase behavior of extended nuclear matter? And, can we observe a phase transition in finite nuclei?   Recent developments, largely coming from complex analyses of data sets measured in 4-pi-type experiments as well as from calculations based on advanced theoretical concepts, will be discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/0011/0011003v1.pdf"}
{"id": "nucl-ex9909005", "abstract": "  The WA98 experiment at the CERN SPS measures Pb+Pb Collisions at 158 AGeV. The scaling properties of the charged particle multiplicity at midrapidity with the number of participants are studied using the SPMD and the MIRAC detector. Neutral pion spectra obtained from the LEDA detector are compared to hydrodynamical parametrizations. The collective flow in the target fragmentation region has been studied using the Plastic Ball detector. The results exhibit a strong dependence on centrality and rapidity. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-ex/pdf/9909/9909005v1.pdf"}
{"id": "nucl-th0404089", "abstract": "  We study the hadron-quark phase transition in the interior of neutron stars (NS). For the hadronic sector, we use a microscopic equation of state (EOS) involving nucleons and hyperons derived within the Brueckner-Bethe-Goldstone many-body theory, with realistic two-body and three-body forces. For the description of quark matter, we employ both the MIT bag model with a density dependent bag constant, and the color dielectric model. We calculate the structure of NS interiors with the EOS comprising both phases, and we find that the NS maximum masses are never larger than 1.7 solar masses, no matter the model chosen for describing the pure quark phase. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0404/0404089v1.pdf"}
{"id": "nucl-th0506057", "abstract": "  The charged current lepton production induced by neutrinos in ^56Fe nuclei has been studied. The calculations have been done for the quasielastic as well as the inelastic reactions assuming Δ dominance and take into account the effect of Pauli blocking, Fermi motion and the renormalization of weak transition strengths in the nuclear medium. The quasielastic production cross section for lepton production are found to be strongly reduced due to nuclear effects while there is about 10", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/0506/0506057v1.pdf"}
{"id": "nucl-th9311005", "abstract": "  We calculate the effective mass of the ω meson in nuclear matter in a relativistic random-phase approximation to the Walecka model. The dressing of the meson propagator is driven by its coupling to particle-hole pairs and nucleon-antinucleon (NN̅) excitations. We report a reduction in the ω-meson mass of about 170 MeV at nuclear-matter saturation density. This reduction arises from a competition between the density-dependent (particle-hole) dressing of the propagator and vacuum polarization (NN̅ pairs). While density-dependent effects lead to an increase in the mass proportional to the classical plasma frequency, vacuum polarization leads to an even larger reduction caused by the reduced effective nucleon mass in the medium. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/9311/9311005v1.pdf"}
{"id": "nucl-th9810033", "abstract": "  The damping of single-particle and collective motion in exotic isotopes is a new topic and its study may shed light on basic problems of nuclear dynamics. For instance, it is known that nuclear structure calculations are not able, as a rule, to account completely for the empirical single-particle damping. In this contribution, we present calculations of the single-particle self-energy in the case of the neutron-rich light nucleus ^28O, by taking proper care of the continuum, and we show that there are important differences with the case of nuclei along the valley of stability. ", "pdf_url": "gs://arxiv-dataset/arxiv/nucl-th/pdf/9810/9810033v1.pdf"}
{"id": "physics0308070", "abstract": "  The self-organized Monte Carlo simulations of 2D Ising ferromagnet on the square lattice are performed. The essence of devised simulation method is the artificial dynamics consisting of the single-spin-flip algorithm of Metropolis supplemented by the random walk in the temperature space. The walk is biased to the critical region through the feedback equation utilizing the memory-based filtering recursion instantly estimating the energy cumulants. The simulations establish that the peak of the temperature probability density function is located nearly the pseudocritical temperature pertaining to canonical equilibrium. In order to eliminate the finite-size effects, the self-organized approach is extended to multi-lattice systems, where feedback is constructed from the pairs of the instantaneous running fourth-order cumulants of the magnetization. The replica-based simulations indicate that several properly chosen steady statistical distributions of the self-organized Monte Carlo systems resemble characteristics of the standard self-organized critical systems. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0308/0308070v2.pdf"}
{"id": "physics0501099", "abstract": "  We investigate the physics of an optically-driven micromotor of biological origin. A single, live red blood cell, when placed in an optical trap folds into a rod-like shape. If the trapping laser beam is circularly polarized, the folded RBC rotates. A model based on the concept of buckling instabilities captures the folding phenomenon; the rotation of the cell is simply understood using the Poincarè sphere. Our model predicts that (i) at a critical intensity of the trapping beam the RBC shape undergoes large fluctuations and (ii) the torque is proportional to the intensity of the laser beam. These predictions have been tested experimentally. We suggest a possible mechanism for emergence of birefringent properties in the RBC in the folded state. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0501/0501099v2.pdf"}
{"id": "physics0504167", "abstract": "  Datasets of online communication often take the form of contact sequences – ordered lists contacts (where a contact is defined as a triple of a sender, a recipient and a time). We propose measures of attractiveness and activity for such data sets and analyze these quantities for anonymized contact sequences from an Internet dating community. For this data set the attractiveness and activity measures show broad power-law like distributions. Our attractiveness and activity measures are more strongly correlated in the real-world data than in our reference model. Effects that indirectly can make active users more attractive are discussed. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0504/0504167v1.pdf"}
{"id": "physics0509139", "abstract": "  In the present paper we discuss the effect of artificial magneto-dielectric substrates on the impedance bandwidth properties of microstrip antennas. The results found in the literature for antenna miniaturization using magnetic or magneto-dielectric substrates are revised, and discussion is addressed to the practically realizable artificial magnetic media operating in the microwave regime. Using a transmission-line model we, first, reproduce the known results for antenna miniaturization with non-dispersive material fillings. Next, a realistic dispersive behavior of a practically realizable artificial substrate is embedded into the model, and we show that frequency dispersion of the substrate plays a very important role in the impedance bandwidth characteristics of the loaded antenna. The impedance bandwidths of reduced size patch antennas loaded with dispersive magneto-dielectric substrates and high-permittivity substrates are compared. It is shown that unlike substrates with dispersion-free permeability, practically realizable artificial substrates with dispersive magnetic permeability are not advantageous in antenna miniaturization. This conclusion is experimentally validated. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0509/0509139v1.pdf"}
{"id": "physics0607024", "abstract": "  We describe a method aiming at increasing the dynamic range of X-ray detectors. Two X-ray exposures of an object are acquired at different dose levels and constitute the only input data. The values of the parameters which are needed to process these images are determined from information contained in the images themselves; the values of two parameters are extracted from the input data. The two input images are finally merged in such a way as to create one image containing useful information in all its entirety. This selective use of parts of each image allows both the contour of the irradiated object to be visible and the high-attenuation areas to retain their image quality corresponding to the information contained in the high-dose image. The benefits of the method are demonstrated with an example involving a head phantom. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0607/0607024v1.pdf"}
{"id": "physics0701203", "abstract": "  Many observations in the dynamics of pedestrian crowds, including various self-organization phenomena, have been successfully described by simple many-particle models. For ethical reasons, however, there is a serious lack of experimental data regarding crowd panic. Therefore, we have analyzed video recordings of the crowd disaster in Mina/Makkah during the Hajj in 1426H on January 12, 2006. They reveal two subsequent, sudden transitions from laminar to stop-and-go and “turbulent” flows, which question many previous simulation models. While the transition from laminar to stop-and-go flows supports a recent model of bottleneck flows [D. Helbing et al., Phys. Rev. Lett. 97, 168001 (2006)], the subsequent transition to turbulent flow is not yet well understood. It is responsible for sudden eruptions of pressure release comparable to earthquakes, which cause sudden displacements and the falling and trampling of people. The insights of this study into the reasons for critical crowd conditions are important for the organization of safer mass events. In particularly, they allow one to understand where and when crowd accidents tend to occur. They have also led to organizational changes, which have ensured a safe Hajj in 1427H. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0701/0701203v2.pdf"}
{"id": "physics0702017", "abstract": "  Real social interactions occur on networks in which each individual is connected to some, but not all, of others. In social dilemma games with a fixed population size, heterogeneity in the number of contacts per player is known to promote evolution of cooperation. Under a common assumption of positively biased payoff structure, well-connected players earn much by playing frequently, and cooperation once adopted by well-connected players is unbeatable and spreads to others. However, maintaining a social contact can be costly, which would prevent local payoffs from being positively biased. In replicator-type evolutionary dynamics, it is shown that even a relatively small participation cost extinguishes the merit of heterogeneous networks in terms of cooperation. In this situation, more connected players earn less so that they are no longer spreaders of cooperation. Instead, those with fewer contacts win and guide the evolution. The participation cost, or the baseline payoff, is irrelevant in homogeneous populations but is essential for evolutionary games on heterogeneous networks. ", "pdf_url": "gs://arxiv-dataset/arxiv/physics/pdf/0702/0702017v4.pdf"}
{"id": "q-bio0309010", "abstract": "  Biophysicists and structural biologists increasingly acknowledge the role played by the mechanical properties of macromolecules as a critical element in many biological processes. This change has been brought about, in part, by the advent of single molecule biophysics techniques that have made it possible to exert piconewton forces on key macromolecules and observe their deformations at nanometer length scales, as well as to observe the mechanical action of macromolecules such as molecular motors. This has opened up immense possibilities for a new generation of mechanical investigations that will respond to such measurements in an attempt to develop a coherent theory for the mechanical behavior of macromolecules under conditions where thermal and chemical effects are on an equal footing with deterministic forces. This paper presents an application of the principles of mechanics to the problem of DNA packaging, one of the key events in the life cycle of bacterial viruses with special reference to the nature of the internal forces that are built up during the DNA packaging process. ", "pdf_url": "gs://arxiv-dataset/arxiv/q-bio/pdf/0309/0309010v1.pdf"}
{"id": "quant-ph0204126", "abstract": "  The quantization of the scalar and electromagnetic fields in the presence of a parabolic mirror is further developed in the context of a geometric optics approximation. We extend results in a previous paper to more general geometries, and also correct an error in one section of that paper. We calculate the mean squared scalar and electric fields near the focal line of a parabolic cylindrical mirror. These quantities are found to grow as inverse powers of the distance from the focus. We give a combination of analytic and numerical results for the mean squared fields. In particular, we find that the mean squared electric field can be either negative or positive, depending upon the choice of parameters. The case of a negative mean squared electric field corresponds to a repulsive Van der Waals force on an atom near the focus, and to a region of negative energy density. Similarly, a positive value corresponds to an attractive force and a possibility of atom trapping in the vicinity of the focus. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0204/0204126v2.pdf"}
{"id": "quant-ph0206014", "abstract": "  Competition for available resources is natural amongst coexisting species, and the fittest contenders dominate over the rest in evolution. The dynamics of this selection is studied using a simple linear model. It has similarities to features of quantum computation, in particular conservation laws leading to destructive interference. Compared to an altruistic scenario, competition introduces instability and eliminates the weaker species in a finite time. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0206/0206014v2.pdf"}
{"id": "quant-ph0206138", "abstract": "  Secure multi-party computing, also called \"secure function evaluation\", has been extensively studied in classical cryptography. We consider the extension of this task to computation with quantum inputs and circuits. Our protocols are information-theoretically secure, i.e. no assumptions are made on the computational power of the adversary. For the weaker task of verifiable quantum secret sharing, we give a protocol which tolerates any t < n/4 cheating parties (out of n). This is shown to be optimal. We use this new tool to show how to perform any multi-party quantum computation as long as the number of dishonest players is less than n/6. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0206/0206138v1.pdf"}
{"id": "quant-ph0212132", "abstract": "  We present a phase-space representation of the hydrogen atom using the Kirkwood-Rikaczek distribution function. This distribution allows us to obtain analytical results, which is quite unique because an exact analytical form of the Wigner functions corresponding to the atom states is not known. We show how the Kirkwood-Rihaczek distribution reflects properties of the hydrogen atom wave functions in position and momentum representations. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0212/0212132v1.pdf"}
{"id": "quant-ph0309148", "abstract": "  We develop a model for a noisy communication channel in which the noise affecting consecutive transmissions is correlated. This model is motivated by fluctuating birefringence of fiber optic links. We analyze the role of entanglement of the input states in optimizing the classical capacity of such a channel. Assuming a general form of an ensemble for two consecutive transmissions, we derive tight bounds on the classical channel capacity depending on whether the input states used for communication are separable or entangled across different temporal slots. This result demonstrates that by an appropriate choice, the channel capacity may be notably enhanced by exploiting entanglement. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0309/0309148v1.pdf"}
{"id": "quant-ph0311017", "abstract": "  We study the universality of scaling of entanglement in Shor's factoring algorithm and in adiabatic quantum algorithms across a quantum phase transition for both the NP-complete Exact Cover problem as well as the Grover's problem. The analytic result for Shor's algorithm shows a linear scaling of the entropy in terms of the number of qubits, therefore difficulting the possibility of an efficient classical simulation protocol. A similar result is obtained numerically for the quantum adiabatic evolution Exact Cover algorithm, which also shows universality of the quantum phase transition the system evolves nearby. On the other hand, entanglement in Grover's adiabatic algorithm remains a bounded quantity even at the critical point. A classification of scaling of entanglement appears as a natural grading of the computational complexity of simulating quantum phase transitions. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0311/0311017v3.pdf"}
{"id": "quant-ph0407018", "abstract": "  It is well known that entangled quantum states can be nonlocal: the correlations between local measurements carried out on these states cannot always be reproduced by local hidden variable models. Svetlichny, followed by others, showed that multipartite quantum states are even more nonlocal than bipartite ones in the sense that nonlocal classical models with (super-luminal) communication between some of the parties cannot reproduce the quantum correlations. Here we study in detail the kinds of nonlocality present in quantum states. More precisely we enquire what kinds of classical communication patterns cannot reproduce quantum correlations. By studying the extremal points of the space of all multiparty probability distributions, in which all parties can make one of a pair of measurements each with two possible outcomes, we find a necessary condition for classical nonlocal models to reproduce the statistics of all quantum states. This condition extends and generalises work of Svetlichny and others in which it was shown that a particular class of classical nonlocal models, the “separable” models, cannot reproduce the statistics of all multiparticle quantum states. Our condition shows that the nonlocality present in some entangled multiparticle quantum states is much stronger than previously thought. We also study the sufficiency of our condition. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0407/0407018v2.pdf"}
{"id": "quant-ph0602038", "abstract": "  We describe a scheme that allows for the generation of any desired N-photon state on demand. Under ideal conditions, this requires only N single photon sources, laser pulses and linear optics elements. First, the sources should be initialised with the help of single-qubit rotations and repeat-until-success two-qubit quantum gates [Lim et al., Phys. Rev. Lett. 95, 030305 (2005)]. Afterwards, the state of the sources can be mapped onto the state of N newly generated photons whenever needed. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0602/0602038v1.pdf"}
{"id": "quant-ph0605010", "abstract": "  We present a quantum teleportation experiment in the quantum relay configuration using the installed telecommunication network of Swisscom. In this experiment, the Bell state measurement occurs well after the entanglement has been distributed, at a point where the photon upon which data is teleported is already far away, and the entangled qubits are photons created from a different crystal and laser pulse than the teleported qubit. A raw fidelity of 0.93+/-0.04 has been achieved using a heralded single-photon source. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0605/0605010v2.pdf"}
{"id": "quant-ph0609222", "abstract": "  In this work we develop a numerical framework to investigate the renormalization of the non-Markovian dynamics of an open quantum system to which dynamical decoupling is applied. We utilize a non-Markovian master equation which is derived from the non-Markovian quantum trajectories formalism. It contains incoherent Markovian dynamics and coherent Schrödinger dynamics as its limiting cases and is capable of capture the transition between them. We have performed comprehensive simulations for the cases in which the system is either driven by the Ornstein-Uhlenbeck noise or or is described by the spin-boson model. The renormalized dynamics under bang-bang control and continuous dynamical decoupling are simulated. Our results indicate that the renormalization of the non-Markovian dynamics depends crucially on the spectral density of the environment and the envelop of the decoupling pulses. The framework developed in this work hence provides an unified approach to investigate the efficiency of realistic decoupling pulses. This work also opens a way to further optimize the decoupling via pulse shaping. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/0609/0609222v1.pdf"}
{"id": "quant-ph9708010", "abstract": "  We construct wave packets for the hydrogen atom labelled by the classical action-angle variables with the following properties. i) The time evolution is exactly given by classical evolution of the angle variables. (The angle variable corresponding to the position on the orbit is now non-compact and we do not get exactly the same state after one period. However the gross features do not change. In particular the wave packet remains peaked around the labels.) ii) Resolution of identity using this overcomplete set involves exactly the classical phase space measure. iii) Semi-classical limit is related to Bohr-Sommerfield quantization. iv) They are almost minimum uncertainty wave packets in position and momentum. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/9708/9708010v2.pdf"}
{"id": "quant-ph9806082", "abstract": "  A quantum telecloning process combining quantum teleportation and optimal quantum cloning from one input to M outputs is presented. The scheme relies on the establishment of particular multiparticle entangled states, which function as multiuser quantum information channels. The entanglement structure of these states is analyzed and shown to be crucial for this type of information processing. ", "pdf_url": "gs://arxiv-dataset/arxiv/quant-ph/pdf/9806/9806082v1.pdf"}