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1102.0572

Feshbach spectroscopy and analysis of the interaction potentials of ultracold sodium

We have studied magnetic Feshbach resonances in an ultracold sample of Na prepared in the absolute hyperfine ground state. We report on the observation of three s-, eight d-, and three g-wave Feshbach resonances, including a more precise determination of two known s-wave resonances, and one s-wave resonance at a magnetic field exceeding 200 mT. Using a coupled-channels calculation we have improved the sodium ground-state potentials by taking into account these new experimental data and derived values for the scattering lengths. In addition, a description of the molecular states leading to the Feshbach resonances in terms of the asymptotic-bound-state model is presented.

1102.0604

A small world of weak ties provides optimal global integration of self-similar modules in functional brain networks

The human brain is organized in functional modules. Such an organization presents a basic conundrum: Modules ought to be sufficiently independent to guarantee functional specialization and sufficiently connected to bind multiple processors for efficient information transfer. It is commonly accepted that small-world architecture of short paths and large local clustering may solve this problem. However, there is intrinsic tension between shortcuts generating small worlds and the persistence of modularity, a global property unrelated to local clustering. Here, we present a possible solution to this puzzle. We first show that a modified percolation theory can define a set of hierarchically organized modules made of strong links in functional brain networks. These modules are “large-world” self-similar structures and, therefore, are far from being small-world. However, incorporating weaker ties to the network converts it into a small world preserving an underlying backbone of well-defined modules. Remarkably, weak ties are precisely organized as predicted by theory maximizing information transfer with minimal wiring cost. This trade-off architecture is reminiscent of the “strength of weak ties” crucial concept of social networks. Such a design suggests a natural solution to the paradox of efficient information flow in the highly modular structure of the brain.

1102.0629

Time-Varying Graphs and Social Network Analysis: Temporal Indicators and Metrics

Most instruments - formalisms, concepts, and metrics - for social networks analysis fail to capture their dynamics. Typical systems exhibit different scales of dynamics, ranging from the fine-grain dynamics of interactions (which recently led researchers to consider temporal versions of distance, connectivity, and related indicators), to the evolution of network properties over longer periods of time. This paper proposes a general approach to study that evolution for both atemporal and temporal indicators, based respectively on sequences of static graphs and sequences of time-varying graphs that cover successive time-windows. All the concepts and indicators, some of which are new, are expressed using a time-varying graph formalism.

1102.0674

Effective Mechanism for Social Recommendation of News

1102.0791

A model of electrowetting, reversed electrowetting, and contact angle saturation.

While electrowetting has many applications, it is limited at large voltages by contact angle saturation, a phenomenon that is still not well understood. We propose a generalized approach for electrowetting that, among other results, can shed new light on contact angle saturation. The model assumes the existence of a minimum (with respect to the contact angle) in the electric energy and accounts for a quadratic voltage dependence ∼U(2) in the low-voltage limit, compatible with the Young-Lippmann formula, and an ∼U(-2) saturation at the high-voltage limit. Another prediction is the surprising possibility of a reversed electrowetting regime, in which the contact angle increases with applied voltage. By explicitly taking into account the effect of the counter-electrode, our model is shown to be applicable to several AC and DC experimental electrowetting-on-dielectric (EWOD) setups. Several features seen in experiments compare favorably with our results. Furthermore, the AC frequency dependence of EWOD agrees quantitatively with our predictions. Our numerical results are complemented with simple analytical expressions for the saturation angle in two practical limits.

1102.0801

General relativity and quantum mechanics in five dimensions

1102.0855

INCOMPLETE CARBON–OXYGEN DETONATION IN TYPE Ia SUPERNOVAE

Incomplete carbon–oxygen detonation with reactions terminating after burning of C12 in the leading C12 + C12 reaction (C-detonation) may occur in the low-density outer layers of white dwarfs exploding as Type Ia supernovae (SNe Ia). Previous studies of carbon–oxygen detonation structure and stability at low densities were performed under the assumption that the velocity of a detonation wave is derived from complete burning of carbon and oxygen to iron. In fact, at densities ρ ⩽ 106 g cm−3 the detonation in SNe Ia may release less than a half of the available nuclear energy. In this paper, we study basic properties of such detonations. We find that the length of an unsupported steady-state C-detonation is ≃30–100 times greater than previously estimated and that the decreased energy has a drastic effect on the detonation stability. In contrast to complete detonations which are one-dimensionally stable, C-detonations may be one-dimensionally unstable and propagate by periodically re-igniting themselves via spontaneous burning. The re-ignition period at ρ ⩽ 106 g cm−3 is estimated to be greater than the timescale of an SN Ia explosion. This suggests that propagation and quenching of C-detonations at these densities could be affected by the instability. Potential observational implications of this effect are discussed.

1102.1016

Resolved atomic interaction sidebands in an optical clock transition.

We report the observation of resolved atomic interaction sidebands (ISB) in the (87)Sr optical clock transition when atoms at microkelvin temperatures are confined in a two-dimensional optical lattice. The ISB are a manifestation of the strong interactions that occur between atoms confined in a quasi-one-dimensional geometry and disappear when the confinement is relaxed along one dimension. The emergence of ISB is linked to the recently observed suppression of collisional frequency shifts. At the current temperatures, the ISB can be resolved but are broad. At lower temperatures, ISB are predicted to be substantially narrower and useful spectroscopic tools in strongly interacting alkaline-earth gases.

1102.1313

Introduction to Categories and Categorical Logic

1102.1461

Time-resolved photoemission by attosecond streaking: extraction of time information

Attosecond streaking of atomic photoemission holds the promise to provide unprecedented information on the release time of the photoelectron. We show that attosecond streaking phase shifts indeed contain timing (or spectral phase) information associated with the Eisenbud–Wigner–Smith time delay matrix of quantum scattering. However, this is only accessible if the influence of the streaking infrared (IR) field on the emission process is properly accounted for. The IR probe field can strongly modify the observed streaking phase shift. We show that the part of the phase shift (‘time shift’) due to the interaction between the outgoing electron and the combined Coulomb and IR laser fields can be described classically. By contrast, the strong initial-state dependence of the streaking phase shift is only revealed through the solution of the time-dependent Schrödinger equation in its full dimensionality. We find a time delay between the hydrogenic 2s and 2p initial states in He+ exceeding 20 as for a wide range of IR intensities and XUV energies.

1102.1468

APPLICATION OF A LOCALIZED CHAOS GENERATED BY RF-PHASE MODULATIONS IN PHASE-SPACE DILUTION ∗

Physics of chaos in a localized phase-space region is exploited to produce a longitudinally uniformly distributed beam. Theoretical study and simulations are used to study its origin and applicability in phase-space dilution of beam bunch. Through phase modulation to a double-rf system, a central region of localized chaos bounded by invariant tori are generated by overlapping parametric resonances. Condition and stability of the chaos will be analyzed. Applications include high-power beam, beam distribution uniformization, and industrial beam irradiation.

1102.1487

Rumor Evolution in Social Networks

Social network is a main tunnel of rumor spreading. Previous studies are concentrated on a static rumor spreading. The content of the rumor is invariable during the whole spreading process. Indeed, the rumor evolves constantly in its spreading process, which grows shorter, more concise, more easily grasped and told. In an early psychological experiment, researchers found about 70% of details in a rumor were lost in the first 6 mouth-to-mouth transmissions \cite{TPR}. Based on the facts, we investigate rumor spreading on social networks, where the content of the rumor is modified by the individuals with a certain probability. In the scenario, they have two choices, to forward or to modify. As a forwarder, an individual disseminates the rumor directly to its neighbors. As a modifier, conversely, an individual revises the rumor before spreading it out. When the rumor spreads on the social networks, for instance, scale-free networks and small-world networks, the majority of individuals actually are infected by the multi-revised version of the rumor, if the modifiers dominate the networks. Our observation indicates that the original rumor may lose its influence in the spreading process. Similarly, a true information may turn to be a rumor as well. Our result suggests the rumor evolution should not be a negligible question, which may provide a better understanding of the generation and destruction of a rumor.

1102.1744

Low Rossby limiting dynamics for stably stratified flow with finite Froude number

In this paper, we explore the strong rotation limit of the rotating and stratified Boussinesq equations with periodic boundary conditions when the stratification is order 1 ([Rossby number] Ro = ε, [Froude number] Fr = O(1), as ε → 0). Using the same framework of Embid & Majda (Geophys. Astrophys. Fluid Dyn., vol. 87, 1998, p. 1), we show that the slow dynamics decouples from the fast. Furthermore, we derive equations for the slow dynamics and their conservation laws. The horizontal momentum equations reduce to the two-dimensional Navier–Stokes equations. The equation for the vertically averaged vertical velocity includes a term due to the vertical average of the buoyancy. The buoyancy equation, the only variable to retain its three-dimensionality, is advected by all three two-dimensional slow velocity components. The conservation laws for the slow dynamics include those for the two-dimensional Navier–Stokes equations and a new conserved quantity that describes dynamics between the vertical kinetic energy and the buoyancy. The leading order potential enstrophy is slow while the leading order total energy retains both fast and slow dynamics. We also perform forced numerical simulations of the rotating Boussinesq equations to demonstrate support for three aspects of the theory in the limit Ro → 0: (i) we find the formation and persistence of large-scale columnar Taylor–Proudman flows in the presence of O(1) Froude number; after a spin-up time, (ii) the ratio of the slow total energy to the total energy approaches a constant and that at the smallest Rossby numbers that constant approaches 1 and (iii) the ratio of the slow potential enstrophy to the total potential enstrophy also approaches a constant and that at the lowest Rossby numbers that constant is 1. The results of the numerical simulations indicate that even in the presence of the low wavenumber white noise forcing the dynamics exhibit characteristics of the theory.

1102.1751

Universal features in sequential and nonsequential two-photon double ionization of helium

We analyze two-photon double ionization of helium in both the nonsequential (({h_bar}/2{pi}){omega} I{sub 2}) regime. We show that the energy spacing {Delta}E=E{sub 1}-E{sub 2} between the two emitted electrons provides the key parameter that controls both the energy and the angular distribution and reveals the universal features present in both the nonsequential and sequential regime. This universality, i.e., independence of ({h_bar}/2{pi}){omega}, is a manifestation of the continuity across the threshold for sequential double ionization. For all photon energies considered, the energy distribution can be described by a universal shape function that contains only the spectral and temporal information entering second-order time-dependent perturbation theory. Angular correlations and distributions are found to be more sensitive to the value of ({h_bar}/2{pi}){omega}. In particular, shake-up interferences have a large effect on the angular distribution. Energy spectra, angular distributions parametrized by the anisotropy parameters {beta}{sub j}, and total cross sections presented in this paper are obtained by fully correlated time-dependent ab initio calculations.

1102.1753

Predictors of short-term decay of cell phone contacts in a large scale communication network

1102.1985

What Stops Social Epidemics?

Theoretical progress in understanding the dynamics of spreading processes on graphs suggests the existence of an epidemic threshold below which no epidemics form and above which epidemics spread to a significant fraction of the graph. We have observed information cascades on the social media site Digg that spread fast enough for one initial spreader to infect hundreds of people, yet end up affecting only 0.1% of the entire network. We find that two effects, previously studied in isolation, combine cooperatively to drastically limit the final size of cascades on Digg. First, because of the highly clustered structure of the Digg network, most people who are aware of a story have been exposed to it via multiple friends. This structure lowers the epidemic threshold while moderately slowing the overall growth of cascades. In addition, we find that the mechanism for social contagion on Digg points to a fundamental difference between information spread and other contagion processes: despite multiple opportunities for infection within a social group, people are less likely to become spreaders of information with repeated exposure. The consequences of this mechanism become more pronounced for more clustered graphs. Ultimately, this effect severely curtails the size of social epidemics on Digg.

1102.1986

Charge fluctuations for particles on a surface exposed to plasma

We develop a stochastic model for the charge fluctuations on a microscopic dust particle resting on a surface exposed to plasma. We find in steady state that the fluctuations are normally distributed with a standard deviation that is proportional to (CTe)1/2, where C is the particle-surface capacitance and Te is the plasma electron temperature. The time for an initially uncharged ensemble of particles to reach the steady state distribution is directly proportional to CTe.

1102.1987

Model-independent searches for new quarks at the LHC

1102.1988

Neutrino fluxes from nonuniversal Higgs mass LSP annihilations in the Sun

We extend our previous studies of the neutrino fluxes expected from neutralino LSP annihilations inside the Sun to include variants of the minimal supersymmetric extension of the Standard Model (MSSM) with squark, slepton and gaugino masses constrained to be universal at the GUT scale, but allowing one or two non-universal supersymmetry-breaking parameters contributing to the Higgs masses (NUHM1,2). As in the constrained MSSM (CMSSM) with universal Higgs masses, there are large regions of the NUHM parameter space where the LSP density inside the Sun is not in equilibrium, so that the annihilation rate may be far below the capture rate, and there are also large regions where the capture rate is not dominated by spin-dependent LSP-proton scattering. The spectra possible in the NUHM are qualitatively similar to those in the CMSSM. We calculate neutrino-induced muon fluxes above a threshold energy of 10 GeV, appropriate for the IceCube/DeepCore detector, for points where the NUHM yields the correct cosmological relic density for representative choices of the NUHM parameters. We find that the IceCube/DeepCore detector can probe regions of the NUHM parameter space in addition to analogues of the focus-point strip and the tip of the coannihilation strip familiar from the CMSSM. These include regions with enhanced Higgsino-gaugino mixing in the LSP composition, that occurs where neutralino mass eigenstates cross over. On the other hand, rapid-annihilation funnel regions in general yield neutrino fluxes that are unobservably small.

1102.1994

Quantum mechanics can reduce the complexity of classical models.

1102.2006

A high-resolution stopwatch for cents

A very low-cost, easy-to-make stopwatch is presented to support various experiments in mechanics. The high-resolution stopwatch is based on two photodetectors connected directly to the microphone input of a sound card. Dedicated free open-source software has been developed and made available to download. The efficiency is demonstrated by a free fall experiment.

1102.2011

Atomic analysis of the (n; t)-reaction of the helium-3 atoms with slow neutrons

Probabilities of formation of various hydrogenic species during the exothermic nuclear (n, 3He; t, p)-reaction of atomic helium-3 with slow neutrons are determined. In particular, we have found that the probability of forming the tritium atom 3H in its ground state is ≈55.192 87 %, while the analogous probability of forming the protium atom 1H in its ground state is ≈1.023 63%. Analogous probabilities of formation of the negatively charged hydrogen ions, i.e. the 3H− and 1H− ions, in the nuclear (n, 3He; t, p)-reaction with slow neutrons are ≈7.8680% and ≈0.065 83%, respectively. We also consider bremsstrahlung from fast fission-type reactions in atomic systems. The spectrum of emitted radiation is analysed.

1102.2024

Slow-light probe of Fermi pairing through an atom-molecule dark state

We consider the two-color photoassociation of a quantum degenerate atomic gas into ground-state diatomic molecules via a molecular dark state. This process can be described in terms of a {Lambda} level scheme that is formally analogous to the situation in electromagnetically induced transparency in atomic systems and therefore can result in slow-light propagation. We show that the group velocity of the light field depends explicitly on whether the atoms are bosons or fermions, as well as on the existence or absence of a pairing gap in the case of fermions, so that the measurement of the group velocity realizes a nondestructive diagnosis of the atomic state and the pairing gap.

1102.2143

Accelerating the solution of families of shifted linear systems with CUDA

We describe the GPU implementation of shifted or multimass iterative solvers for sparse linear systems of the sort encountered in lattice gauge theory. We provide a generic tool that can be used by those without GPU programming experience to accelerate the simulation of a wide array of theories. We stress genericity, which is important to allow the simulation of candidate theories for new physics at LHC, and for the study of various supersymmetric theories. We find significant speed ups, which we conservatively bound below at at least twelve times, that promise to put a variety of research questions within practical reach.

1102.2166

Social Structure of Facebook Networks

We study the social structure of Facebook “friendship” networks at one hundred American colleges and universities at a single point in time, and we examine the roles of user attributes–gender, class year, major, high school, and residence–at these institutions. We investigate the influence of common attributes at the dyad level in terms of assortativity coefficients and regression models. We then examine larger-scale groupings by detecting communities algorithmically and comparing them to network partitions based on user characteristics. We thereby examine the relative importance of different characteristics at different institutions, finding for example that common high school is more important to the social organization of large institutions and that the importance of common major varies significantly between institutions. Our calculations illustrate how microscopic and macroscopic perspectives give complementary insights on the social organization at universities and suggest future studies to investigate such phenomena further.

1102.2436

X-ray Study of Rekindled Accretion in the Classical Nova V2491 Cygni

We conducted an X-ray spectroscopic study of the classical nova V2491 Cygni using our target-of-opportunity observation data with the Suzaku and XMM-Newton satellites as well as archived data with the Swift satellite. Medium-resolution (R~10-50) spectra were obtained using the X-ray CCD spectrometers at several post-nova epochs on days 9, 29, 40, 50, and 60-150 in addition to a pre-nova interval between days -322 and -100 all relative to the time when the classical nova was spotted. We found remarkable changes in the time series of the spectra: (a) In the pre-nova phase and on day 9, the 6.7 keV emission line from Fe XXV was significantly detected. (b) On day 29, no such emission line was found. (c) On day 40, the 6.7 keV emission line emerged again. (d) On days 50 and 60-150, three emission lines at 6.4, 6.7, and 7.0 keV respectively from quasi-neutral Fe, Fe XXV, and Fe XXVI were found. Statistically significant changes of the Fe K line intensities were confirmed between day 29 and 50. Based on these phenomena, we conclude that (1) the post-nova evolution can be divided into two different phases, (2) ejecta is responsible for the X-ray emission in the earlier phase, while rekindled accretion is for the later phase, and (3) the accretion process is considered to be reestablished as early as day 50 when the quasi-neutral Fe emission line emerged, which is a common signature of accretion from magnetic cataclysmic variables.

1102.2446

Compact USB measurement and analysis system for real-time fluctuation enhanced sensing

Measuring the resistance fluctuations of gas sensors provides new opportunities to enhance the selectivity and sensitivity of the sensor. Taking advantage of this possibility requires special low-noise measurement hardware and software to acquire data and perform analysis. In our talk we will present a small, USB-powered device capable of doing precise measurement of the resistance fluctuations of different kinds of gas sensors. We have developed a graphical user interface software to control the parameters of the measurement, to collect data and perform real time analysis on the measured data. The analysis is based on a PCA algorithm, which is proven to be a high performance tool to support fluctuation enhanced sensing. The system has been tested on Taguchi and carbon nanotube based gas sensors as well. The main advantages of the system include the small form factor, low cost and the fully featured software performing all required data analysis operations. Complemented with a gas sensor and an optional test chamber, the setup can serve as an efficient tool for practical fluctuation-enhanced gas sensing.

1102.2472

Development of the analog ASIC for multi-channel readout X-ray CCD camera

1102.2474

Capitalist Science

The economic structure of basic science is currently socialist, funded by the public at large through taxes for the benefit of the public at large. This socialist system should be augmented by a capitalist system, in which basic science is also funded by private investors who reap financial benefit from the sale of subsequent technologies based on the knowledge obtained from the research funded by their investments. A capitalist system will provide benefits extending from the broad target audience of this paper — which includes politicians, financiers, economists, and scientists in all fields — to the average taxpayer and consumer. Capitalist science will better align the incentives of scientists with taxpayer interests, channel more money into basic science, lower your taxes, and generally improve the quality of your life.

1102.2476

GAMMA-RAY EMISSION FROM THE VELA PULSAR MODELED WITH THE ANNULAR GAP AND THE CORE GAP

The Vela pulsar represents a distinct group of γ-ray pulsars. Fermi γ-ray observations reveal that it has two sharp peaks (P1 and P2) in the light curve, with a phase separation of 0.42 and a third peak (P3) in the bridge. The location and intensity of P3 are energy dependent. We use the three-dimensional magnetospheric model for the annular and core gaps to simulate the γ-ray light curves and the phase-averaged and phase-resolved spectra. We found that the acceleration electric field along a field line in the annular gap region decreases with height. Emission at the high-energy GeV band originates from the synchro-curvature radiation (mainly curvature radiation) of accelerated primary particles, while the synchrotron radiation from secondary particles contributes somewhat to the low-energy γ-ray band (0.1–0.3 GeV). The γ-ray light curve peaks P1 and P2 are generated in the annular gap region near the altitude of null charge surface, whereas P3 and the bridge emission are generated in the core gap region. The intensity and location of P3 at different energy bands depend on the emission altitudes. The radio emission from the Vela pulsar should be generated in a high-altitude narrow region of the annular gap, which leads to a radio phase lag of ∼0.13 prior to the first γ-ray peak.

1102.2892

Disordered holographic systems: Functional renormalization

We study quenched disorder in strongly correlated systems via holography, focusing on the thermodynamic effects of mild electric disorder. Disorder is introduced through a random potential which is assumed to self-average on macroscopic scales. Studying the flow of this distribution with energy scale leads us to develop a holographic functional renormalization scheme. We test this scheme by computing thermodynamic quantities and confirming that the Harris criterion for relevance, irrelevance or marginality of quenched disorder holds.

1102.2896

Vacuum stability and the Cholesky decomposition

1102.3192

Relativistic particle in a three-dimensional box

1102.3196

Invited Paper: Design and modeling of a transistor vertical-cavity surface-emitting laser

1102.3209

Clouds and the Faint Young Sun Paradox

Abstract. We investigate the role which clouds could play in resolving the Faint Young Sun Paradox (FYSP). Lower solar luminosity in the past means that less energy was absorbed on Earth (a forcing of −50 W m−2 during the late Archean), but geological evidence points to the Earth having been at least as warm as it is today, with only very occasional glaciations. We perform radiative calculations on a single global mean atmospheric column. We select a nominal set of three layered, randomly overlapping clouds, which are both consistent with observed cloud climatologies and reproduced the observed global mean energy budget of Earth. By varying the fraction, thickness, height and particle size of these clouds we conduct a wide exploration of how changed clouds could affect climate, thus constraining how clouds could contribute to resolving the FYSP. Low clouds reflect sunlight but have little greenhouse effect. Removing them entirely gives a forcing of +25 W m−2 whilst more modest reduction in their efficacy gives a forcing of +10 to +15 W m−2. For high clouds, the greenhouse effect dominates. It is possible to generate +50 W m−2 forcing from enhancing these, but this requires making them 3.5 times thicker and 14 K colder than the standard high cloud in our nominal set and expanding their coverage to 100% of the sky. Such changes are not credible. More plausible changes would generate no more than +15 W m−2 forcing. Thus neither fewer low clouds nor more high clouds can provide enough forcing to resolve the FYSP. Decreased surface albedo can contribute no more than +5 W m−2 forcing. Some models which have been applied to the FYSP do not include clouds at all. These overestimate the forcing due to increased CO2 by 20 to 25% when pCO2 is 0.01 to 0.1 bar.

1102.3430

Infrared luminosity functions of AKARI Sloan Digital Sky Survey galaxies

By cross-correlating the AKARI all-sky survey in six infrared (IR) bands (9, 18, 65, 90, 140 and 160 μm) with the Sloan Digital Sky Survey (SDSS) galaxies, we identified 2357 IR galaxies with a spectroscopic redshift. This is not just one of the largest samples of local IR galaxies, but AKARI provides crucial far-IR (FIR) bands for accurately measuring the galaxy spectral energy distribution (SED) across the peak of the dust emission at > 100 μ m. By fitting modern IR SED models to the AKARI photometry, we measured the total infrared luminosity (L_(IR)) of individual galaxies. Using this L_(IR), we constructed the luminosity functions (LF) of IR galaxies at a median redshift of z= 0.031. The LF agrees well with that at z= 0.0082 (the Revised Bright Galaxy Sample), showing smooth and continuous evolution towards higher redshift LFs measured in the AKARI North Ecliptic Pole (NEP) deep field. By integrating the IR LF weighted by L_(IR), we measured the local cosmic IR luminosity density of Ω_(IR_= (3.8^(+5.8)_(−1.2)) × 10^8 L_⊙ Mpc^(−3). We separate galaxies into active galactic nuclei (AGN), star-forming galaxies (SFG) and composite by using the [N ii]/Hα versus [O iii]/Hβ line ratios. The fraction of AGN shows a continuous increase with increasing L_(IR) from 25 to 90 per cent at 9 10^(11) L_⊙, coinciding with the break of both the SFG and AGN IR LFs. At L_(IR)≤ 10^(11) L_⊙, SFG dominates IR LFs. Only 1.1 ± 0.1 per cent of Ω_(IR) is produced by luminous infrared galaxies (L_(IR) > 10^(11) L_⊙), and only 0.03 ± 0.01 per cent by ultraluminous infrared galaxies (L_(IR) > 10^(12) L_⊙) in the local Universe. Compared with high-redshift results from the AKARI NEP deep survey, we observed a strong evolution of Ω^(SFG)IR^∝ (1 +z)^(4.1±0.4) and Ω^(AGN)IR^∝ (1+z)^(4.1±0.5). Our results show that all of our measured quantities (IR LFs, L^*, Ω^(AGN)IR, Ω^(SFG)IR) show smooth and steady increase from lower redshift (the Revised Bright Galaxy Sample) to higher redshift (the AKARI NEP deep survey).

1102.3432

Phenomenological consequences of sub-leading terms in see-saw formulas

1102.3434

Detecting vanishing dimensions via primordial gravitational wave astronomy.

Lower dimensionality at higher energies has manifold theoretical advantages as recently pointed out by Anchordoqui et al. [arXiv:1003.5914]. Moreover, it appears that experimental evidence may already exist for it: A statistically significant planar alignment of events with energies higher than TeV has been observed in some earlier cosmic ray experiments. We propose a robust and independent test for this new paradigm. Since (2+1)-dimensional spacetimes have no gravitational degrees of freedom, gravity waves cannot be produced in that epoch. This places a universal maximum frequency at which primordial waves can propagate, marked by the transition between dimensions. We show that this cutoff frequency may be accessible to future gravitational wave detectors such as the Laser Interferometer Space Antenna.

1102.3440

Algorithm 923: Efficient Numerical Computation of the Pfaffian for Dense and Banded Skew-Symmetric Matrices

Computing the Pfaffian of a skew-symmetric matrix is a problem that arises in various fields of physics. Both computing the Pfaffian and a related problem, computing the canonical form of a skew-symmetric matrix under unitary congruence, can be solved easily once the skew-symmetric matrix has been reduced to skew-symmetric tridiagonal form. We develop efficient numerical methods for computing this tridiagonal form based on Gaussian elimination, using a skew-symmetric, blocked form of the Parlett-Reid algorithm, or based on unitary transformations, using block Householder transformations and Givens rotations, that are applicable to dense and banded matrices, respectively. We also give a complete and fully optimized implementation of these algorithms in Fortran (including a C interface), and also provide Python, Matlab and Mathematica implementations for convenience. Finally, we apply these methods to compute the topological charge of a class D nanowire, and show numerically the equivalence of definitions based on the Hamiltonian and the scattering matrix.

1102.3453

How students blend conceptual and formal mathematical reasoning in solving physics problems

Current conceptions of quantitative problem-solving expertise in physics incorporate conceptual reasoning in two ways: for selecting relevant equations (before manipulating them) and for checking whether a given quantitative solution is reasonable (after manipulating the equations). We make the case that problem-solving expertise should include opportunistically blending of conceptual and formal mathematical reasoning even while manipulating equations. We present analysis of interviews with two students, Alex and Pat. Interviewed students were asked to explain a particular equation and solve a problem using that equation. Alex used and described the equation as a computational tool. By contrast, Pat found a shortcut to solve the problem. His shortcut blended mathematical operations with conceptual reasoning about physical processes, reflecting a view—expressed earlier in his explanation of the equation—that equations can express an overarching conceptual meaning. Using case studies of Alex and Pat, we argue that this opportunistic blending of conceptual and formal mathematical reasoning (i) is a part of problem-solving expertise, (ii) can be described in terms of cognitive elements called symbolic forms (Sherin, 2001), and (iii) is a feasible instructional target.

1102.3455

Minimal dark matter and leptogenesis

1102.3467

General coevolution of topology and dynamics in networks

We present a general framework for the study of coevolution in dynamical systems. This phenomenon consists of the coexistence of two dynamical processes on networks of interacting elements: node state change and rewiring of links between nodes. The process of rewiring is described in terms of two basic actions: disconnection and reconnection between nodes, both based on a mechanism of comparison of their states. We assume that the process of rewiring and node state change occur with probabilities Pr and Pc, respectively, independent of each other. The collective behavior of a coevolutionary system can be characterized on the space of parameters (Pr, Pc). As an application, for a voter-like node dynamics we find that reconnections between nodes with similar states lead to network fragmentation. The critical boundaries for the onset of fragmentation in networks with different properties are calculated on this space. We show that coevolution models correspond to curves on this space describing functional relations between Pr and Pc. The occurrence of a one-large-domain phase and a fragmented phase in the network is predicted for diverse models, and agreement is found with some earlier results. The collective behavior of the system is also characterized on the space of parameters for the disconnection and reconnection actions. In a region of this space, we find a behavior where different node states can coexist for very long times on one large, connected network.

1102.3476

Slow electron attachment as a probe of cluster evaporation processes.

Neutral alkali clusters efficiently capture low-energy electrons with the aid of long-range polarization attraction. Upon attachment, the electron affinity and kinetic energy are dissipated into vibrations, heating the cluster and triggering evaporation of atoms and dimers. This process offers a novel means to explore nanocluster bonding and evaporation kinetics. The present work investigates the formation of Na(N)(-). A crossed-beam experiment reveals that relative anion abundances become strongly and nontrivially restructured with respect to the neutral precursor beam. This restructuring is explained in quantitative detail by an analysis of evaporative cascades initiated by the attachment. The analysis thus furnishes a complete description of the electron attachment process, from initial attraction to final rearrangement of the cluster population. In addition, the paper describes a systematic derivation of cluster evaporation kinetics and internal temperature distributions; a new relation between the dissociation energies of cationic, neutral, and anionic metal clusters; and a scenario for inferring the neutral cluster population in the supersonic beam from the cationic mass spectrum.

1102.3477

On the ground state of Yang–Mills theory

1102.3660

Zakopane lectures on loop gravity

This is a first version of the introductory lectures on loop quantum gravity that I will give at the quantum gravity school in Zakopane. The theory is presented in self-contained form, without emphasis on its derivation from classical general relativity. Dynamics is given in the covariant form. Some applications are described, including the recent derivation of de Sitter cosmology from full quantum gravity.

1102.3692

Nonlinear structure formation with the environmentally dependent dilaton

We have studied the nonlinear structure formation of the environmentally dependent dilaton model using N-body simulations. We find that the mechanism of suppressing the scalar fifth force in high-density regions works very well. Within the parameter space allowed by the solar-system tests, the dilaton model predicts small deviations of the matter power spectrum and the mass function from their {Lambda}CDM counterparts. The importance of taking full account of the nonlinearity of the model is also emphasized.

1102.3708

Dynamical 3-Space: Cosmic Filaments, Sheets and Voids

Observations of weak gravitational lensing combined with statistical tomographic techniques have revealed that galaxies have formed along filaments, essentially one-dimensional lines or strings, which form sheets and voids. These have, in the main, been interpreted as "dark matter" effects. To the contrary here we report the discovery that the dynamical 3-space theory possesses such filamentary solutions. These solutions are purely space self-interaction effects, and are attractive to matter, and as well generate electromagnetic lensing. This theory of space has explained bore hole anomalies, supermassive black hole masses in spherical galaxies and globular clusters, flat rotation curves of spiral galaxies, and other gravitational anomalies. The theory has two constants, G and alpha, where the bore hole experiments show that alpha approx 1/137 is the fine structure constant.

1102.3712

Black swans or dragon-kings? A simple test for deviations from the power law

1102.3752

Effective range expansion in various scenarios of EFT()

Using rigorous solutions, we compare the ERE parameters obtained in three different scenarios of EFT() in nonperturbative regime. A scenario with unconventional power counting (like KSW) is shown to be disfavored by the PSA data, while the one with elaborate prescription of renormalization but keeping conventional power counting intact seems more promising.

1102.3784

Observing another Universe through ringholes and Klein-bottle holes

Spanish Relativity Meeting, ERE2011, Madrid, 29th August to 2nd September, 2011. http://teorica.fis.ucm.es/ERE2011/

1102.3929

The semiclassical limit of causal dynamical triangulations

1102.3931

Social consensus through the influence of committed minorities

We show how the prevailing majority opinion in a population can be rapidly reversed by a small fraction p of randomly distributed committed agents who consistently proselytize the opposing opinion and are immune to influence. Specifically, we show that when the committed fraction grows beyond a critical value p(c) ≈ 10%, there is a dramatic decrease in the time T(c) taken for the entire population to adopt the committed opinion. In particular, for complete graphs we show that when p < pc, T(c) ~ exp [α(p)N], whereas for p>p(c), T(c) ~ ln N. We conclude with simulation results for Erdős-Rényi random graphs and scale-free networks which show qualitatively similar behavior.

1102.3937

Axiomatic ranking of network role similarity

A key task in analyzing social networks and other complex networks is role analysis: describing and categorizing nodes by how they interact with other nodes. Two nodes have the same role if they interact with equivalent sets of neighbors. The most fundamental role equivalence is automorphic equivalence. Unfortunately, the fastest algorithm known for graph automorphism is nonpolynomial. Moreover, since exact equivalence is rare, a more meaningful task is measuring the role similarity between any two nodes. This task is closely related to the link-based similarity problem that SimRank addresses. However, SimRank and other existing simliarity measures are not sufficient because they do not guarantee to recognize automorphically or structurally equivalent nodes. This paper makes two contributions. First, we present and justify several axiomatic properties necessary for a role similarity measure or metric. Second, we present RoleSim, a role similarity metric which satisfies these axioms and which can be computed with a simple iterative algorithm. We rigorously prove that RoleSim satisfies all the axiomatic properties and demonstrate its superior interpretative power on both synthetic and real datasets.

1102.4055

Parisian ruin probability for spectrally negative Lévy processes

In this note we give, for a spectrally negative Levy process, a compact formula for the Parisian ruin probability, which is defined by the probability that the process exhibits an excursion below zero, with a length that exceeds a certain fixed period r. The formula involves only the scale function of the spectrally negative Levy process and the distribution of the process at time r.

1102.4101

Scaling and Hierarchy in Urban Economies

In several recent publications, Bettencourt, West and collaborators claim that properties of cities such as gross economic production, personal income, numbers of patents filed, number of crimes committed, etc., show super-linear power-scaling with total population, while measures of resource use show sub-linear power-law scaling. Re-analysis of the gross economic production and personal income for cities in the United States, however, shows that the data cannot distinguish between power laws and other functional forms, including logarithmic growth, and that size predicts relatively little of the variation between cities. The striking appearance of scaling in previous work is largely artifact of using extensive quantities (city-wide totals) rather than intensive ones (per-capita rates). The remaining dependence of productivity on city size is explained by concentration of specialist service industries, with high value-added per worker, in larger cities, in accordance with the long-standing economic notion of the "hierarchy of central places".

1102.4337

Black funnels and droplets in thermal equilibrium

1102.4350

On Phenomenology of Complex Scientific Systems

Performance evolution of a number of complex scientific and technical systems demonstrate exponential progress with time exp(+t/C) . The speed of progress C - a measure of difficulty and complexity - is analyzed for high energy elementary particle colliders, astrophysical searches for galaxies and exoplanets, protein structure determination and compared with computers and thermonuclear fusion reactors. An explanation of the characteristic exponential progress is offered.

1102.4362

Equivalence principle and gravitational redshift.

We investigate leading order deviations from general relativity that violate the Einstein equivalence principle in the gravitational standard model extension. We show that redshift experiments based on matter waves and clock comparisons are equivalent to one another. Consideration of torsion balance tests, along with matter-wave, microwave, optical, and Mössbauer clock tests, yields comprehensive limits on spin-independent Einstein equivalence principle-violating standard model extension terms at the 10(-6) level.

1102.4369

SPECTRUM AND WAVE FUNCTIONS OF U(1)2+1 LATTICE GAUGE THEORY FROM MONTE CARLO HAMILTONIAN

We address an old problem in lattice gauge theory — the computation of the spectrum and wave functions of excited states. Our method is based on the Hamiltonian formulation of lattice gauge theory. Using the method of Monte Carlo with importance sampling, we construct a stochastic basis of Bargmann link states, drawn from a physical probability density function. In the next step, we compute transition amplitudes between stochastic basis states. Then, we extract energy spectra and wave functions from a matrix of transition elements. To test this method, we apply it to U(1) lattice gauge theory in (2+1) dimensions and compute the energy spectrum, wave functions and thermodynamic functions of the electric Hamiltonian of this theory. We compare the numerical results with the analytical results and observe a reasonable scaling of energies and wave functions in the variable of time.

1102.4615

Jets plus Missing Energy with an Autofocus

Jets plus missing transverse energy is one of the main search channels for new physics at the LHC. A major limitation lies in our understanding of QCD backgrounds. Using jet merging we can describe the number of jets in typical background channels in terms of a staircase scaling, including theory uncertainties. The scaling parameter depends on the particles in the final state and on cuts applied. Measuring the staircase scaling will allow us to also predict the effective mass for Standard Model backgrounds. Based on both observables we propose an analysis strategy avoiding model specific cuts which returns information about the color charge and the mass scale of the underlying new physics.

1102.4624

Renormalization group and the Planck scale

I discuss the renormalization group approach to gravity, and its link to Weinberg’s asymptotic safety scenario, and give an overview of results with applications to particle physics and cosmology.

1102.4639

Non-Conservative Diffusion and its Application to Social Network Analysis

The random walk is fundamental to modeling dynamic processes on networks. Metrics based on the random walk have been used in many applications from image processing to Web page ranking. However, how appropriate are random walks to modeling and analyzing social networks? We argue that unlike a random walk, which conserves the quantity diffusing on a network, many interesting social phenomena, such as the spread of information or disease on a social network, are fundamentally non-conservative. When an individual infects her neighbor with a virus, the total amount of infection increases. We classify diffusion processes as conservative and non-conservative and show how these differences impact the choice of metrics used for network analysis, as well as our understanding of network structure and behavior. We show that Alpha-Centrality, which mathematically describes non-conservative diffusion, leads to new insights into the behavior of spreading processes on networks. We give a scalable approximate algorithm for computing the Alpha-Centrality in a massive graph. We validate our approach on real-world online social networks of Digg. We show that a non-conservative metric, such as Alpha-Centrality, produces better agreement with empirical measure of influence than conservative metrics, such as PageRank. We hope that our investigation will inspire further exploration into the realms of conservative and non-conservative metrics in social network analysis.

1102.4665

Time-resolved predissociation of the vibrationless level of the B state of CH3I.

The predissociation dynamics of the vibrationless level of the first Rydberg 6s (B (1)E) state of CH(3)I has been studied by femtosecond-resolved velocity map imaging of both the CH(3) and I photofragments. The kinetic energy distributions of the two fragments have been recorded as a function of the pump-probe delay, and as a function of excitation within the umbrella and stretching vibrational modes of the CH(3) fragment. These observations are made by using (2 + 1) Resonant Enhanced MultiPhoton Ionization (REMPI) via the state of CH(3) to detect specific vibrational levels of CH(3). The vibrational branching fractions of the CH(3) are recovered by using the individual vibrationally state-selected CH(3) distributions to fit the kinetic energy distribution obtained by using nonresonant multiphoton ionization of either the I or the CH(3) fragment. The angular distributions and rise times of the two fragments differ significantly. These observations can be rationalized through a consideration of the alignment of the CH(3) fragment and the effect of this alignment on its detection efficiency. Two additional dissociation channels are detected: one associated with Rydberg states near 9.2 eV that were observed previously in photoelectron studies, and one associated with photodissociation of the parent cation around 15 eV.

1102.4847

Quantum Riemann Surfaces in Chern-Simons Theory

We construct from first principles the operators $\hat A_M$ that annihilate the partition functions (or wavefunctions) of three-dimensional Chern-Simons theory with gauge groups $SU(2)$, $SL(2,\mathbb{R})$, or $SL(2,\mathbb{C})$ on knot complements $M$. The operator $\hat A_M$ is a quantization of a knot complement's classical $A$-polynomial $A_M(\ell,m)$. The construction proceeds by decomposing three-manifolds into ideal tetrahedra, and invoking a new, more global understanding of gluing in topological quantum field theory to put them back together. We advocate in particular that, properly interpreted, 'gluing $=$ symplectic reduction.' We also arrive at a new finite-dimensional state integral model for computing the analytically continued 'holomorphic blocks' that compose any physical Chern-Simons partition function.

1102.4853

Energy and environmental aspects of mobile communication systems

1102.4857

Freudenthal Duality and Generalized Special Geometry

1102.4863

Solitons and black holes in a generalized Skyrme model with dilaton-quarkonium field

Skyrme theory is among the viable effective theories which emerge from the low-energy limit of quantum chromodynamics. Many of its generalizations include also a dilaton. Here we find new self-gravitating solutions, both solitons and black holes, in a generalized Skyrme model in which a dilaton is present. The investigation of the properties of the solutions is done numerically. We find that the introduction of the dilaton in the theory does not change the picture qualitatively, only quantitatively. The model considered here has one free parameter more than the Einstein-Skyrme model which comes from the potential of the dilaton. We have applied also the turning point method to establish that one of the black-hole branches of solutions is unstable. The turning point method here is based on the first law of black-hole thermodynamics a detailed derivation of which is given in the Appendix of the paper.

1102.4873

Weighted Radial Variation for Node Feature Classification

Connections created from a node-edge matrix have been traditionally difficult to visualize and analyze because of the number of flows to be rendered in a limited feature or cartographic space. Because analyzing connectivity patterns is useful for understanding the complex dynamics of human and information flow that connect non-adjacent space, techniques that allow for visual data mining or static representations of system dynamics are a growing field of research. Here, we create a Weighted Radial Variation (WRV) technique to classify a set of nodes based on the configuration of their radially-emanating vector flows. Each entity's vector is syncopated in terms of cardinality, direction, length, and flow magnitude. The WRV process unravels each star-like entity's individual flow vectors on a 0-360{\deg} spectrum, to form a unique signal whose distribution depends on the flow presence at each step around the entity, and is further characterized by flow distance and magnitude. The signals are processed with an unsupervised classification method that clusters entities with similar signatures in order to provide a typology for each node in the system of spatial flows. We use a case study of U.S. county-to-county human incoming and outgoing migration data to test our method.

1102.4876

Network connectivity during mergers and growth: optimizing the addition of a module.

The principal eigenvalue λ of a network's adjacency matrix often determines dynamics on the network (e.g., in synchronization and spreading processes) and some of its structural properties (e.g., robustness against failure or attack) and is therefore a good indicator for how "strongly" a network is connected. We study how λ is modified by the addition of a module, or community, which has broad applications, ranging from those involving a single modification (e.g., introduction of a drug into a biological process) to those involving repeated additions (e.g., power-grid and transit development). We describe how to optimally connect the module to the network to either maximize or minimize the shift in λ, noting several applications of directing dynamics on networks.

1102.4878

Robustness of networks against propagating attacks under vaccination strategies

We study the effect of vaccination on the robustness of networks against propagating attacks that obey the susceptible–infected–removed model. By extending the generating function formalism developed by Newman (2005 Phys. Rev. Lett. 95 108701), we analytically determine the robustness of networks that depends on the vaccination parameters. We consider the random defense where nodes are vaccinated randomly and the degree-based defense where hubs are preferentially vaccinated. We show that, when vaccines are inefficient, the random graph is more robust against propagating attacks than the scale-free network. When vaccines are relatively efficient, the scale-free network with the degree-based defense is more robust than the random graph with the random defense and the scale-free network with the random defense.

1102.4920

Holomorphic supercurves and supersymmetric sigma models

We introduce a natural generalisation of holomorphic curves to morphisms of supermanifolds, referred to as holomorphic supercurves. More precisely, supercurves are morphisms from a Riemann surface, endowed with the structure of a supermanifold which is induced by a holomorphic line bundle, to an ordinary almost complex manifold. They are called holomorphic if a generalised Cauchy-Riemann condition is satisfied. We show, by means of an action identity, that holomorphic supercurves are special extrema of a supersymmetric action functional.

1102.4955

Observatories in Space

Space observatories are having major impacts on our knowledge of the Universe, from the Solar neighborhood to the cosmological background, opening many new windows out of reach to ground-based observatories. Celestial objects emit all over the electromagnetic spectrum, and the Earth's atmosphere blocks a large part of them. Moreover, space offers a very stable environment from where the whole sky can be observed with no (or very little) perturbations, providing new observing possibilities. This chapter presents a few striking examples of astrophysics space observatories and of major results spanning from the Solar neighborhood and our Galaxy to external galaxies, quasars and the cosmological background.

1102.5091

Screening bulk curvature in the presence of large brane tension

We study a flat brane solution in an effective 5D action for cascading gravity in six dimensions, and propose a mechanism to screen extrinsic curvature in the presence of a large tension on the brane. The screening mechanism leaves the bulk Riemann-flat, thus making it simpler to generalize large extra-dimension dark energy models to higher codimensions. By studying an action with cubic interactions for the brane-bending scalar mode, we find that the perturbed action suffers from ghostlike instabilities for positive tension. The solution can be made ghost-free for sufficiently small negative tension, though the connection to 6D cascading gravity is less clear in this case.

1102.5096

Cosmological production of noncommutative black holes

We investigate the pair creation of noncommutative black holes in a background with a positive cosmological constant. As a first step we derive the noncommutative geometry inspired Schwarzschild--de Sitter solution. By varying the mass and the cosmological constant parameters, we find several spacetimes compatible with the new solution: positive-mass spacetimes admit one cosmological horizon and two, one, or no black hole horizons, while negative-mass spacetimes have just a cosmological horizon. These new black holes share the properties of the corresponding asymptotically flat solutions, including the nonsingular core and thermodynamic stability in the final phase of the evaporation. As a second step we determine the action which generates the matter sector of gravitational field equations and we construct instantons describing the pair production of black holes and the other admissible topologies. As a result we find that for current values of the cosmological constant the de Sitter background is quantum mechanically stable according to experience. However, positive-mass noncommutative black holes and solitons would have plentifully been produced during inflationary times for Planckian values of the cosmological constant. As a special result we find that, in these early epochs of the Universe, Planck size black holes production would have been largely disfavored. We also find a potential instability for production of negative-mass solitons.

1102.5103

Leading-order behavior of the correlation energy in the uniform electron gas

We show that, in the high-density limit, restricted M{\o}ller-Plesset (RMP) perturbation theory yields $E_{\text{RMP}}^{(2)} = \pi^{-2}(1-\ln 2) \ln r_s + O(r_s^0)$ for the correlation energy per electron in the uniform electron gas, where $r_s$ is the Seitz radius. This contradicts an earlier derivation which yielded $E_{\text{RMP}}^{(2)} = O(\ln|\ln r_s|)$. The reason for the discrepancy is explained.

1102.5113

THE ROLE OF DARK MATTER INTERACTION IN GALAXY CLUSTERS

We consider a toy model to analyze the consequences of dark matter interaction with a dark energy background on the overall rotation of galaxy clusters and the misalignment between their dark matter and baryon distributions when compared to ΛCDM predictions. The interaction parameters are found via a genetic algorithm search. The results obtained suggest that interaction is a basic phenomenon whose effects are detectable even in simple models of galactic dynamics.

1102.5343

Equilateral Non-Gaussianity and New Physics on the Horizon

We examine the effective theory of single-field inflation in the limit where the scalar perturbations propagate with a small speed of sound. In this case the non-linearly realized time-translation symmetry of the Lagrangian implies large interactions, giving rise to primordial non-Gaussianities. When the non-Gaussianities are measurable, these interactions will become strongly coupled unless new physics appears close to the Hubble scale. Due to its proximity to the Hubble scale, the new physics is not necessarily decoupled from inflationary observables and can potentially affect the predictions of the model. To understand the types of corrections that may arise, we construct weakly-coupled completions of the theory and study their observational signatures.

1102.5354

Precision angle sensor using an optical lever inside a Sagnac interferometer.

We built an ultra-low-noise angle sensor by combining a folded optical lever and a Sagnac interferometer. The instrument has a measured noise floor of 1.3 prad/√Hz at 2.4 kHz. We achieve this record angle sensitivity using a proof-of-concept apparatus with a conservative N=11 bounces in the optical lever. This technique could be extended to reach subpicoradian/√Hz sensitivities with an optimized design.

1102.5356

H = xp model revisited and the Riemann zeros.

Berry and Keating conjectured that the classical Hamiltonian H = xp is related to the Riemann zeros. A regularization of this model yields semiclassical energies that behave, on average, as the nontrivial zeros of the Riemann zeta function. However, the classical trajectories are not closed, rendering the model incomplete. In this Letter, we show that the Hamiltonian H = x(p + ℓ(p)²/p) contains closed periodic orbits, and that its spectrum coincides with the average Riemann zeros. This result is generalized to Dirichlet L functions using different self-adjoint extensions of H. We discuss the relation of our work to Polya's fake zeta function and suggest an experimental realization in terms of the Landau model.

1102.5408

An extension to the Luscher's finite volume method above inelastic threashold (formalism)

An extension of the Lüscher’s finite volume method above inel astic thresholds is proposed. It is fulfilled by extendind the procedure recently proposed by HA L-QCD Collaboration for a single channel system. Focusing on the asymptotic behaviors of the Nambu-Bethe-Salpeter (NBS) wave functions (equal-time) near spatial infinity, a coupled cha nnel extension of effective Schrödinger equation is constructed by introducing an energy-independ ent interaction kernel. Because the NBS wave functions contain the information of T-matrix at lo ng distance, S-matrix can be obtained by solving the coupled channel effective Schrödinge r equation in the infinite volume.

1102.5647

A commuting network model: going to the bulk

The influence of commuting in socio-economic dynamics increases constantly. Analysing and modelling the networks formed by commuters to help decision-making regarding the land-use has become crucial. This paper presents a simple spatial interaction simulated model with only one parameter. The proposed algorithm considers each individual who wants to commute, starting from their living place to all their workplaces. It decides where the location of the workplace following the classical rule inspired from the gravity law consisting in a compromise between the job offers and the distance to the jobs. The further away the job offer is, the more important it must be in order to be considered. Inversely, only the quantity of offers is important for the decision when these offers are close. The paper also presents a comparative analysis of the structure of the commuting networks of the four European regions to which we apply our model. The model is calibrated and validated on these regions. Results from the analysis shows that the model is very efficient in reproducing most of the statistical properties of the network given by the data sources.

1103.0002

Finite temperature structure of the compactified standard model

1103.0003

Supersymmetric Galileons

Galileon theories are of considerable interest since they allow for stable violations of the null energy condition. Since such violations could have occurred during a highenergy regime in the history of our universe, we are motivated to study supersymmetric extensions of these theories. This is carried out in this paper, where we construct generic classes of N = 1 supersymmetric Galileon Lagrangians. They are shown to admit non-equivalent stress-energy tensors and, hence, vacua manifesting differing conditions for violating the null energy condition. The temporal and spatial fluctuations of all component fields of the supermultiplet are analyzed and shown to be stable on a large number of such backgrounds. In the process, we uncover a surprising connection between conformal Galileon and ghost condensate theories, allowing for a deeper understanding of both types of theories.

1103.0012

BPS invariants of N=4 gauge theory on a surface

Generating functions of BPS invariants for N=4 U(r) gauge theory on a Hirzebruch surface with r=2 and 3 are computed. The BPS invariants provide the Betti numbers of moduli spaces of semi-stable sheaves. The generating functions for r=2 are expressed in terms of higher level Appell functions for a certain polarization of the surface. The level corresponds to the self-intersection of the base curve of the Hirzebruch surface. The non-holomorphic functions are determined, which added to the holomorphic generating functions provide functions which transform as a modular form.

1103.0021

Solving mazes with memristors: a massively-parallel approach

Solving mazes is not just a fun pastime: They are prototype models in several areas of science and technology. However, when maze complexity increases, their solution becomes cumbersome and very time consuming. Here, we show that a network of memristors--resistors with memory--can solve such a nontrivial problem quite easily. In particular, maze solving by the network of memristors occurs in a massively parallel fashion since all memristors in the network participate simultaneously in the calculation. The result of the calculation is then recorded into the memristors' states and can be used and/or recovered at a later time. Furthermore, the network of memristors finds all possible solutions in multiple-solution mazes and sorts out the solution paths according to their length. Our results demonstrate not only the application of memristive networks to the field of massively parallel computing, but also an algorithm to solve mazes, which could find applications in different fields.

1103.0048

On the structural properties of small-world networks with finite range of shortcut links

We explore a new variant of Small-World Networks (SWNs), in which an additional parameter ($r$) sets the length scale over which shortcuts are uniformly distributed. When $r=0$ we have an ordered network, whereas $r=1$ corresponds to the original SWN model. These short-range SWNs have a similar degree distribution and scaling properties as the original SWN model. We observe the small-world phenomenon for $r \ll 1$ indicating that global shortcuts are not necessary for the small-world effect. For short-range SWNs, the average path length changes nonmonotonically with system size, whereas for the original SWN model it increases monotonically. We propose an expression for the average path length for short-range SWNs based on numerical simulations and analytical approximations.

1103.0274

Solar system constraints on Rindler acceleration

We discuss the classical tests of general relativity in the presence of Rindler acceleration. Among these tests, the perihelion shifts give the tightest constraints and indicate that the Pioneer anomaly cannot be caused by a universal solar system Rindler acceleration. We address potential caveats for massive test objects. Our tightest bound on Rindler acceleration that comes with no caveats is derived from radar echo delay and yields $|a|l3\text{ }\text{ }\mathrm{nm}/{\mathrm{s}}^{2}$.

1103.0298

An efficient method for solving highly anisotropic elliptic equations

1103.0508

Bubble nucleation in stout beers.

Bubble nucleation in weakly supersaturated solutions of carbon dioxide-such as champagne, sparkling wines, and carbonated beers-is well understood. Bubbles grow and detach from nucleation sites: gas pockets trapped within hollow cellulose fibers. This mechanism appears not to be active in stout beers that are supersaturated solutions of nitrogen and carbon dioxide. In their canned forms these beers require additional technology (widgets) to release the bubbles which will form the head of the beer. We extend the mathematical model of bubble nucleation in carbonated liquids to the case of two gases and show that this nucleation mechanism is active in stout beers, though substantially slower than in carbonated beers and confirm this by observation. A rough calculation suggests that despite the slowness of the process, applying a coating of hollow porous fibers to the inside of a can or bottle could be a potential replacement for widgets.

1103.0537

Comment on `Finite size corrections to the radiation reaction force in classical electrodynamics' [[arXiv:1005.2617]

I show that the main statement of [Phys. Rev. Lett. 105, 094802 (2010), arXiv:1005.2617] is wrong. Other inconsistences of this Letter are also discussed.

1103.0546

Quantum control of proximal spins using nanoscale magnetic resonance imaging

1103.0547

Disentangling galaxy environment and host halo mass

The properties of both observed galaxies and dark matter haloes in simulations depend on their environment. The term “environment” has, however, been used to describe a wide variety of measures that may or may not correlate with each other. Popular measures of environment include, for example, the distance to the N th nearest neighbour, the number density of objects within some distance, or, for the case of galaxies only, the mass of the host dark matter halo. Here we use results from the Millennium simulation and a semi-analytic model for galaxy formation to quantify the relations between different measures of environment and halo mass. We show that the environmental parameters used in the observational literature are in effect measures of halo mass, even if they are measured for a fixed stella r mass. The strongest correlation between environmental density and halo mass arises when the number of objects is counted out to a distance of 1.5 ‐ 2 times the virial radius of the host h alo and when the galaxies/haloes are required to be relatively bright/massive. For observational studies this virial radius is no t easily determined, but the number of neighbours out to 1 ‐ 2 h −1 Mpc gives a similarly strong correlation with halo mass. For the distance to the N th nearest neighbour the (anti-)correlation with halo mass is nearly as strong provided N > 2. We demonstrate that this environmental parameter becomes insensitive to halo mass if it is constructed from dimensionless quantities. This can be achieved by scaling the minimum luminosity/mass of neighbours to that of the object that the environment is determined for and by dividing the distance to a length scale associated with either the neighbour or the galaxy under consideration. We show how such a halo mass independent environmental parameter can be defin ed for both observational and numerical studies. The results presented here will help fut ure studies to disentangle the effects of halo mass and external environment on the properties of galaxies and dark matter haloes.

1103.0548

Investigating a model of optimised AGN feedback

Feedback heating from AGN in massive galaxies and galaxy clusters can be thought of as a naturally occurring control system which plays a significant role in regulating both star formation rates and the X-ray luminosity of the surrounding hot gas. In the simplest case, negative feedback can be viewed as a system response that is `optimised' to minimise deviations from equilibrium, such that the system rapidly evolves towards a steady state. However, a general solution of this form appears to be incompatible with radio observations which indicate intermittent AGN outbursts. Here, we explore an energetically favourable scenario in which feedback is required to both balance X-ray gas cooling, and minimise the sum of the energy radiated by the gas and the energy injected by the AGN. This specification is equivalent to ensuring that AGN heating balances the X-ray gas cooling with minimum black hole growth. It is shown that minimum energy heating occurs in discrete events, and not at a continuous, constant level. Furthermore, systems with stronger feedback experience proportionally more powerful heating events, but correspondingly smaller duty cycles. Interpreting observations from this perspective would imply that stronger feedback occurs in less massive objects - elliptical galaxies, rather than galaxy clusters. One direct consequence of this effect would be that AGN heating events are sufficiently powerful to expel hot gas from the gravitational potential of a galaxy, but not a galaxy cluster, which is consistent with theoretical explanations for the steepening of the L_X-T relation at temperatures below 1-2 keV.

1103.0553

M2-branes and Fano 3-folds

A class of supersymmetric gauge theories arising from M2-branes probing Calabi–Yau 4-folds which are cones over smooth toric Fano 3-folds is investigated. For each model, the toric data of the mesonic moduli space are derived using the forward algorithm. The generators of the mesonic moduli space are determined using the Hilbert series. The spectrum of scaling dimensions for chiral operators is computed.

1103.0559

Some (3+1)-dimensional vortex solutions of the CP{sup N} model

We present a class of solutions of the CP{sup N} model in (3+1) dimensions. We suggest that they represent vortexlike configurations. We also discuss some of their properties. We show that some configurations of vortices have a divergent energy per unit length while for the others such an energy has a minimum for a very special orientation of vortices. We also discuss the Noether charge densities of these vortices.

1103.0560

Measurements of the Partial Branching Fraction for B to Xulnu and the Determination of Vub

We measure partial branching fractions for the inclusive charmless semileptonic decay of $\Bxulnu$, and present determinations of the CKM matrix element $\Vub$. This analysis is based on a sample of 467 million $\FourS$ decays into $\BB$ pairs, collected with the \babar\ detector at the PEP-II $e^{+} e^{-}$ storage rings. We select events where one of the B mesons is fully reconstructed in a hadronic decay mode and the other B decays semileptonically into an electron or a muon. We then use the invariant mass, $\mx$, of the hadronic system, the invariant mass squared, $q^{2}$, of the lepton and neutrino pair, the lepton momentum in the in the $B$ meson rest frame $\Pl$, the kinematic variable $P_{+}$ or one of their combinations as discriminating variables to isolate $\Bxulnu$ decays from the background. We then measure the partial branching fractions in various regions of phase space These partial branching fractions are translated into values of $\Vub$ using several theoretical calculations. An estimate based on the most inclusive analysis gives $\Vub = (4.31\pm 0.35) \times 10^{-3}$. Furthermore, we place a limit on isospin breaking in $B\to X_u\ell\nu$ decays of 9% at 90% C.L. using separate measurements of partial branching ratios for $B^0$ and $B^+$.

1103.0595

Meteoritics and cosmology among the Aboriginal cultures of Central Australia

The night sky played an important role in the social structure, oral traditions, and cosmology of the Arrernte and Luritja Aboriginal cultures of Central Australia. A component of this cosmology relates to meteors, meteorites, and impact craters. This paper discusses the role of meteoritic phenomena in Arrernte and Luritja cosmology, showing not only that these groups incorporated this phenomenon in their cultural traditions, but that their oral traditions regarding the relationship between meteors, meteorites and impact structures suggests the Arrernte and Luritja understood that they are directly related.

1103.0599

Laser driving of Superradiant scattering at variable incidence angle

We study superradiant scattering from a Bose-Einstein condensate using a pump laser incident at variable angle and show the presence of asymmetrically populated scattering modes. Experimental data reveal that the direction of the pump laser plays a significant role in the formation of this asymmetry, result which is in good agreement with numerical simulations based on coupled Maxwell-Schr\"{o}dinger equations. Our study complements the gap of previous work in which the pump laser was only applied along the short axis or the long axis of a condensate, and extends our knowledge about cooperative scattering processes.

1103.0701

Analytical maximum-likelihood method to detect patterns in real networks

In order to detect patterns in real networks, randomized graph ensembles that preserve only part of the topology of an observed network are systematically used as fundamental null models. However, the generation of them is still problematic. Existing approaches are either computationally demanding and beyond analytic control or analytically accessible but highly approximate. Here, we propose a solution to this long-standing problem by introducing a fast method that allows one to obtain expectation values and standard deviations of any topological property analytically, for any binary, weighted, directed or undirected network. Remarkably, the time required to obtain the expectation value of any property analytically across the entire graph ensemble is as short as that required to compute the same property using the adjacency matrix of the single original network. Our method reveals that the null behavior of various correlation properties is different from what was believed previously, and is highly sensitive to the particular network considered. Moreover, our approach shows that important structural properties (such as the modularity used in community detection problems) are currently based on incorrect expressions, and provides the exact quantities that should replace them.

1103.0717

The dynamics of financial stability in complex networks