cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Evidence for strong dynamical evolution in disk galaxies through the last 11 Gyr. GHASP VIII: A local reference sample of rotating disk galaxies for high redshift studies
Creators: name: Epinat, B.
name: Amram, P.
name: Balkowski, C.
name: Marcelin, M.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: [Abridged] Due to their large distances, high-z galaxies are observed at a very low spatial resolution. In order to disentangle the evolution of galaxy kinematics from low resolution effects, we have used Fabry-Perot 3D Ha data-cubes of 153 nearby isolated galaxies from the GHASP survey to simulate data-cubes of galaxies at z=1.7. We show that the inner velocity gradient is lowered and is responsible for a peak in the velocity dispersion map. Toy-models of rotating disks have been built to recover the parameters from low resolution data. The poor resolution makes the kinematical inclination uncertain and the center difficult to recover. The major axis is retrieved with an accuracy higher than 5deg for 70% of the sample. Toy-models also enable to retrieve statistically the maximum velocity and the mean velocity dispersion of galaxies with a satisfying accuracy. This validates the use of the Tully-Fisher relation for high-z galaxies but the loss of resolution induces a lower slope at high-z. We conclude that the main kinematic parameters are better constrained for galaxies with an optical radius larger than three times the seeing. The simulated data have been compared to actual high-z galaxies data in the redshift range 3>z>0.4. For rotation-dominated galaxies, we find that the use of the velocity dispersion central peak as a signature of rotating disks may misclassify slow and solid body rotators (~30% of our sample). We show that the projected data cannot reproduce the high velocity dispersion observed in high-z galaxies except when no beam smearing correction is applied. This unambiguously means that, at the opposite of local evolved galaxies, there exists at high redshift at least a population of disk galaxies for which a large fraction of the dynamical support is due to random motions.
description: 61 pages, 20 figures, accepted for publication in MNRAS
XMM-Newton detection of soft time lags in the TDE candidate AT 2018fyk
Creators: name: Zhang, Wenda
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: In this letter we report a tentative detection of soft time lags (i.e. variability of softer photons lags behind the variability of harder photons) in one $XMM-Newton$ observation of the tidal disruption event (TDE) candidate AT 2018fyk while the source was in the hard spectral state. The lags are detected at $6.51\times10^{-5}~\rm Hz$. The amplitude of the lags with respect to 0.5$-$1 keV monotonically decreases with the photon energy, from $\sim 1200~\rm s$ at 0.3$-$0.5 keV to $\sim -4200~\rm s$ at 3$-$5 keV (in our convention a positive lag means lagging behind the reference band). We find that the amplitude is proportional to the logarithm of the energy separation between the examined band and the reference band. The energy-dependent covariance spectrum indicates that the correlated variability is more likely to be associated with the non-thermal radiation. The soft lags are difficult to reconcile with the reverberation scenario that are used to explain the soft lags in active galactic nuclei. On the other hand, the observed soft lags are consistent with the picture that the soft X-rays are down-scattered hard X-rays by the outflow as predicted by ``unification'' models of TDEs.
description: 5 pages, 3 figures; accepted for publication in MNRAS Letters
Invariant random fields in vector bundles and application to cosmology
Creators: name: Malyarenko, Anatoliy
Publisher: name: arXiv
Year: 2009
Subjects: subject: Probability (math.PR)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 60G60

description: We develop the theory of invariant random fields in vector bundles. The spectral decomposition of an invariant random field in a homogeneous vector bundle generated by an induced representation of a compact connected Lie group $G$ is obtained. We discuss an application to the theory of cosmic microwave background, where $G=SO(3)$. A theorem about equivalence of two different groups of assumptions in cosmological theories is proved.
description: 39 pages, 3 tables
Multi-wavelength Searches for Particle Dark Matter
Creators: name: Profumo, Stefano
name: Ullio, Piero
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: If dark matter particles pair annihilate into stable Standard Model particles, a population of energetic, non-thermal electrons and positrons is necessarily produced. The secondary radiation resulting from the energy losses of this non-standard population (including synchrotron and inverse Compton up-scattering of background radiation photons) in turn produces a peculiar multi-wavelength spectrum, extending from radio to gamma-ray frequencies. We give here an overview of multi-wavelength searches for dark matter, including the expected injection spectrum and production rate of electrons and positrons from dark matter annihilation, the computation of the effects of propagation and energy losses and the actual multi-wavelength emission. We then outline the application of this general framework to the case of galaxy clusters (specifically Coma, 1E 0657-56 - the so-called Bullet cluster - and Ophiuchus) and of dwarf spheroidal galaxies (including Draco, Fornax, Ursa Minor and Carina). We also review the application of multi-wavelength search strategies to our own Milky Way, and more specifically to the Galactic center environment, to dark galactic mini-halos and to the so-called WMAP haze and other radio data. We argue that multi-wavelength observations will complement gamma-ray observations as probes of particle dark matter, since the expected luminosities at different frequencies are generically comparable. The indirect search for dark matter with astronomical observations at various frequencies is therefore a crucial and indispensable element in the quest for the fundamental nature of dark matter.
description: 23 pages, 3 figures; This invited contribution was published as Chapter 27 of "Particle Dark Matter: Observations, Models and Searches" edited by Gianfranco Bertone. The book webpage is at http://cambridge.org/us/catalogue/catalogue.asp?isbn=9780521763684
Comparative study of semiclassical approaches to quantum dynamics
Creators: name: Schubert, G.
name: Filinov, V. S.
name: Matyash, K.
name: Schneider, R.
name: Fehske, H.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Quantum states can be described equivalently by density matrices, Wigner functions or quantum tomograms. We analyze the accuracy and performance of three related semiclassical approaches to quantum dynamics, in particular with respect to their numerical implementation. As test cases, we consider the time evolution of Gaussian wave packets in different one-dimensional geometries, whereby tunneling, resonance and anharmonicity effects are taken into account. The results and methods are benchmarked against an exact quantum mechanical treatment of the system, which is based on a highly efficient Chebyshev expansion technique of the time evolution operator.
description: 32 pages, 8 figures, corrected typos and added references; version as published
MOESM1 of Selection and validation of reference genes for quantitative expression analysis of miRNAs and mRNAs in Poplar
Creators: name: Tang, Fang
name: Chu, Liwei
name: Shu, Wenbo
name: He, Xuejiao
name: Wang, Lijuan
name: Lu, Mengzhu
Publisher: name: figshare
Year: 2019
Subjects: subject: Biophysics
subject: Biochemistry
subject: Genetics
subject: FOS: Biological sciences
subject: Molecular Biology
subject: Sociology
subject: FOS: Sociology
subject: Biological Sciences not elsewhere classified
subject: Infectious Diseases
subject: FOS: Health sciences
subject: Plant Biology

description: Additional file 1: Fig. S1. The melting curves of candidate reference genes. Fig. S2. The PCR amplification specificities of candidate reference genes detected by agarose gel electrophoresis.
Interference channel capacity region for randomized fixed-composition codes
Creators: name: Chang, Cheng
Publisher: name: arXiv
Year: 2009
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: The randomized fixe-composition with optimal decoding error exponents are studied \cite{Raul_ISIT,Raul_journal} for the finite alphabet interference channel (IFC) with two transmitter-receiver pairs. In this paper we investigate the capacity region of the randomized fixed-composition coding scheme. A complete characterization of the capacity region of the said coding scheme is given. The inner bound is derived by showing the existence of a positive error exponent within the capacity region. A simple universal decoding rule is given. The tight outer bound is derived by extending a technique first developed in \cite{Dueck_RC} for single input output channels to interference channels. It is shown that even with a sophisticated time-sharing scheme among randomized fixed-composition codes, the capacity region of the randomized fixed-composition coding is not bigger than the known Han-Kobayashi \cite{Han_Kobayashi} capacity region. This suggests that the average behavior of random codes are not sufficient to get new capacity regions.
description: In preparation for IEEE Transactions on IT
Phase diagram of imbalanced strongly interacting fermions on a one-dimensional optical lattice
Creators: name: Anfossi, Alberto
name: Barbiero, Luca
name: Montorsi, Arianna
Publisher: name: arXiv
Year: 2009
Subjects: subject: Quantum Physics (quant-ph)
subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: We show that the Hubbard Hamiltonian with particle-assisted tunneling rates --recently proposed to model a fermionic mixture near a broad Feshbach resonance-- displays a ground state phase diagram with superfluid, insulating, and phase separated regimes. In the latter case, when the populations are balanced the two phases coexist in microscopic antiferromagnetic domains. Macroscopic phase segregation into a high-density superfluid of molecules, and a low-density Fermi liquid of single atoms appears in the density profile above a critical polarization p_c.
description: 4 pages, 3 figures
Relation of the reproductive biology of plants to the structure and function of four plant communities
Creators: name: Pojar, Jim
Publisher: name: University of British Columbia
Year: 2010

description: Four plant communities of southwestern British Columbia were studied in an attempt to answer the following related questions: (1) do communities of harsh physical environments exhibit any characteristic phytosociological features? (2) are there any correlations between environmental harshness and certain synecological properties of such communities ? (3) are species of such communities selected for reproductive specializations that tend to reduce their genetic variability? The four communities (representing three types of herbaceous or semi-shrubby vegetation) were a salt marsh, two coastal sphagnum bogs, and a subalpine meadow. In answer to the first two questions, the findings of this investigation indicate that: (a) species population structure becomes more aggregated as environmental heterogeneity and physical stress increase, and less aggregated as succession proceeds and interspecific competition increases. (b) interspecific association and correlation, both negative and positive, increase as environmental heterogeneity and competition increase. (c) levels of polyploidy within communities appear to be correlated with environmental rigor (broadly defined). (d) the most abundant species within a community are the most variable and presumably have the largest niches ; niche size and population variability decrease as interspecific competition increases. (e) within a community, ecological distinctiveness reduces interspecific competition; communities under the least stress (especially seasonal stress) have the most ecologically dissimilar1 species. (f) dominance decreases as species diversity increases, and species diversity is roughly correlated with overall environmental severity. In answer to the last question: (a) all four communities are dominated by predominantly outcrossing species; there is no major shift to self-pollination or apomixis in any of the communities. (b) an index of potential recombination was devised, embodying a number of aspects of reproductive biology, according to which there is no significant difference in potential recombination, on the average, between species of the four different communities. Plant communities and their constituent species both respond to evolutionary forces, but more or less independently, at different rates, and often in different or even opposite ways. Environmental stress has a powerful effect on the structure and function of plant communities, but in an evolutionary sense there is little difference between normal (mesic, zonal) environments and extreme or azonal environments to an individual species. Different selection pressures have been operating in salt marshes, sphagnum bogs, and subalpine meadows, but the present study indicates that, on the average, the resultant evolutionary strategies of the species of these communities are equivalent.
Relaxing the cosmological constant in the extreme ultra-infrared
Creators: name: Porto, Rafael A.
name: Zee, A.
Publisher: name: arXiv
Year: 2009
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We speculate on the dynamical critical behavior of gravity in the extreme ultra-infrared (EuIR) sector and a mechanism to relax the cosmological constant. We show that in the EuIR the cosmological constant term could be made irrelevant for values of the dynamical critical exponent z_EuIR greater than one. We discuss a possible realization of this idea that connects the relaxation of the cosmological constant to the ratio between the EuIR and IR scales, where the latter serves as the 'UV' cutoff of our (ultra long distance) effective theory, with z_IR ~ 1. For distances smaller than the IR regime Lorentz invariance emerges. We entertain the possibility that the effective description of the universe may not be Lorentz invariant at much larger scales. We discuss why local physics cannot detect the 'natural' value for the density of dark energy below the IR scale, and briefly comment on possible connections with holography.
Stellar population and kinematics of NGC404
Creators: name: Bouchard, A.
name: Prugniel, Ph.
name: Koleva, M.
name: Sharina, M.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: NGC404 is a nearly face-on nearby low-luminosity lenticular galaxy. Probing its characteristics provides a wealth of information on the details of possible evolution processes of dS0 galaxies which may not be possible in other, more distant objects. In order to study its kinematics and star formation history, we obtained long slit spectroscopy at the OHP 1m93 telescope along the major and minor axes of NGC404. The spectra have a resolution R = 3600 covering a wavelength range from 4600 to 5500 A. The data are fitted against the Pegase.HR stellar population models to derive simultaneously the internal stellar kinematics, ages and metallicities. Firstly, the global properties of the galaxy are analyzed by fitting a single model and to the data and looking at the kinematic variations and SSP equivalent age and metallicities as a function of radius. Afterwards, the stellar populations are decomposed into 4 components that are individually analyzed. NGC404 clearly shows two radial velocity inversions along its major axis. The kinematically decoupled core rotates in the same direction as the neutral hydrogen shell that surrounds the galaxy. We resolved the star formation history in the core of the galaxy ino 4 events: A very young (< 150 Myr, and [Fe/H] = 0.4) component with constant on-going star formation, a second young (430 Myr) component with [Fe/H] = 0.1, an intermediate population (1.7 Gyr) which has [Fe/H] = -0.05 and, finally, an old (12 Gyr) component with [Fe/H] = -1.26. The two young components fade very quickly with radius, leaving only the intermediate and old population at a radius of 25" (370 pc) from the centre. We conclude that NGC404 had a spiral morphology about 1 Gyr ago and that one or many merger events has triggered a morphological transition.
description: 8 pages, 8 figures, accepted for publication in A&A
Charged Higgs production at photon colliders in 2HDM-III
Creators: name: Martinez, R.
name: Rodriguez, J. -Alexis
name: Sanchez, S.
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We study charged Higgs production in the process $γγ\to A^0\to W^- H^+$. The processes $γγ\to A^0$ are loop mediated in a 2HDM. This is due to the fact that photons only couple directly to charged particles and the Higgs only couples to particles with mass acquired via Higgs mechanism. Although in MSSM the contribution from the process $γγ\to A^0$ is too small, it has been found that in a more general 2HDM it could be enhanced. On the other hand, the boson $A^0$ can decay in $W^- H^+$ at tree level and the charged Higgs can decay in fermions. So, the whole process under study is $γγ\to A^0\to (W^-\to lν) (H^+\to f_if_j)$ in 2HDM-III. Evidence about charged Higgs existence could demonstrate that structure of the Higgs sector has several multiplets.
description: 5 pages, 4 figures, to appear Brazilian Journal of Physics
Antiferromagnetic phase transition in four-layered high-T_c superconductors Ba_2Ca_3Cu_4O_8(F_yO_{1-y})_2 with T_c=55-102 K: Cu- and F-NMR studies
Creators: name: Shimizu, S.
name: Mukuda, H.
name: Kitaoka, Y.
name: Kito, H.
name: Kodama, Y.
name: Shirage, P. M.
name: Iyo, A.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We report on magnetic characteristics in four-layered high-T_c superconductors Ba_2Ca_3Cu_4O_8(F_yO_{1-y})_2 with apical fluorine through Cu- and F-NMR measurements. The substitution of oxygen for fluorine at the apical site increases the carrier density (N_h) and T_c from 55 K up to 102 K. The NMR measurements reveal that antiferromagnetic order, which can uniformly coexist with superconductivity, exists up to N_h = 0.15, which is somewhat smaller than N_h = 0.17 being the quantum critical point (QCP) for five-layered compounds. The fact that the QCP for the four-layered compounds moves to a region of lower carrier density than for five-layered ones ensures that the decrease in the number of CuO_2 layers makes an interlayer magnetic coupling weaker.
description: 7 pages, 6 gigures, Submitted to J. Phys. Soc. Jpn
Collision of Two Stellar Associations in the Nearby Gum Nebula
Creators: name: Yep, Alexandra C.
name: White, Russel J.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Based on Gaia DR2 data and new CHIRON radial velocities, we have discovered that two nearby stellar associations UPK 535 (318.08 $\pm$ 0.29 pc, $25^{+15}_{-10}$ Myr, 174 stars) and Yep 3 (339.54 $\pm$ 0.25 pc , $45^{+55}_{-20}$ Myr, 297 stars) in the Gum Nebula have recently collided. We project stars' current positions, motions, and measurement uncertainties backward and forward through time in a 10,000-trial Monte Carlo simulation. On average, the associations' centres of mass come within 18.89 $\pm$ 0.73 pc of each other 0.84 $\pm$ 0.03 Myr ago. A mode of 54 $\pm$ 7 close ($$70 per cent of trials and multiple close encounters in $\sim$30 per cent. On average, the closest approach of any two stars is 0.13 $\pm$ 0.06 pc, or 27,000 $\pm$ 12,000 au. With impulse-tracing values up to $2.7^{+3.1}_{-1.1}$ M$_{\odot}$ pc$^{-2}$ km$^{-1}$ s, such close encounters could perturb stars' Oort cloud comets (if present), cause heavy bombardment events for exoplanets (if present), and reshape solar system architectures. Finally, an expansion of our simulation suggests other associations in the region are also interacting. Association collisions may be commonplace, at least in the Gum Nebula straddling the Galactic plane, and may spur solar system evolution more than previously recognized.
description: 11 pages, 9 figures, 4 tables, to be published in MNRAS
Galactic kinematics with modified Newtonian dynamics
Creators: name: Bienaymé, O.
name: Famaey, B.
name: Wu, X.
name: Zhao, H. S.
name: Aubert, D.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We look for observational signatures that could discriminate between Newtonian and modified Newtonian (MOND) dynamics in the Milky Way, in view of the advent of large astrometric and spectroscopic surveys. Indeed, a typical signature of MOND is an apparent disk of "phantom" dark matter, which is uniquely correlated with the visible disk-density distribution. Due to this phantom dark disk, Newtonian models with a spherical halo have different signatures from MOND models close to the Galactic plane. The models can thus be differentiated by measuring dynamically (within Newtonian dynamics) the disk surface density at the solar radius, the radial mass gradient within the disk, or the velocity ellipsoid tilt angle above the Galactic plane. Using the most realistic possible baryonic mass model for the Milky Way, we predict that, if MOND applies, the local surface density measured by a Newtonist will be approximately 78 Msun/pc2 within 1.1 kpc of the Galactic plane, the dynamically measured disk scale-length will be enhanced by a factor of 1.25 with respect to the visible disk scale-length, and the local vertical tilt of the velocity ellipsoid at 1 kpc above the plane will be approximately 6 degrees. None of these tests can be conclusive for the present-day accuracy of Milky Way data, but they will be of prime interest with the advent of large surveys such as GAIA.
description: 5 pages
Detecting the Wind-Driven Shapes of Extrasolar Giant Planets from Transit Photometry
Creators: name: Barnes, Jason W.
name: Cooper, Curtis S.
name: Showman, Adam P.
name: Hubbard, William B.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: Several processes can cause the shape of an extrasolar giant planet's shadow, as viewed in transit, to depart from circular. In addition to rotational effects, cloud formation, non-homogenous haze production and movement, and dynamical effects (winds) could also be important. When such a planet transits its host star as seen from Earth, the asphericity will introduce a deviation in the transit lightcurve relative to the transit of a perfectly spherical (or perfectly oblate) planet. We develop a theoretical framework to interpret planet shapes. We then generate predictions for transiting planet shapes based on a published theoretical dynamical model of HD189733b. Using these shape models we show that planet shapes are unlikely to introduce detectable lightcurve deviations (those >~1e-5 of the host star), but that the shapes may lead to astrophysical sources of systematic error when measuring planetary oblateness, transit time, and impact parameter.
description: ApJ, accepted -- scheduled for publication 2009 December 1
Scalar-Scalar, Scalar-Tensor, and Tensor-Tensor Correlators from Anisotropic Inflation
Creators: name: Gumrukcuoglu, A. E.
name: Himmetoglu, Burak
name: Peloso, Marco
Publisher: name: arXiv
Year: 2010
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We compute the phenomenological signatures of a model (Watanabe et al' 09) of anisotropic inflation driven by a scalar and a vector field. The action for the vector is U(1) invariant, and the model is free of ghost instabilities. A suitable coupling of the scalar to the kinetic term of the vector allows for a slow roll evolution of the vector vev, and hence for a prolonged anisotropic expansion; this provides a counter example to the cosmic no hair conjecture. We compute the nonvanishing two point correlation functions between physical modes of the system, and express them in terms of power spectra with angular dependence. The anisotropy parameter g_* for the scalar-scalar spectrum (defined as in the Ackerman et al '07 parametrization) turns out to be negative in the simplest realization of the model, which, therefore, cannot account for the angular dependence emerged in some analyses of the WMAP data. A g_* of order -0.1 is achieved when the energy of the vector is about 6-7 orders of magnitude smaller than that of the scalar during inflation. For such values of the parameters, the scalar-tensor correlation (which is in principle a distinctive signature of anisotropic spaces) is smaller than the tensor-tensor correlation.
Gravitational waves in vector inflation
Creators: name: Golovnev, Alexey
name: Mukhanov, Viatcheslav
name: Vanchurin, Vitaly
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We discuss the gravitational waves (GW) in the context of vector inflation. We derive the action for tensor perturbations and find that tachyonic instabilities are present in most (but not all) of the inflationary models with large fields. In contrast, the stability of the small field inflation ($A_μA^μ\ll\frac{1}{N}$) is ensured by the usual slow-roll conditions, where $N$ is the total number of fields. For example, the Coleman-Weinberg potential and the power-law inflation are always stable in the small fields limit with an approximately flat spectrum of GW. We also provide some examples which lead to a rapid decay of GW and predict the absence of tensor modes in the CMB.
description: 6 pages
Uniform mixing of antiferromagnetism and high-T_c superconductivity in multilayered copper oxides Ba_2Ca_{n-1}Cu_nO_{2n}F_2 with apical fluorines (n=2,3,4): Cu-NMR/NQR and F-NMR
Creators: name: Shimizu, S.
name: Sakaguchi, T.
name: Mukuda, H.
name: Kitaoka, Y.
name: Shirage, P. M.
name: Kodama, Y.
name: Iyo, A.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We report Cu-NMR/NQR and F-NMR studies on the multilayered high-T_c copper oxides Ba_2Ca_{n-1}Cu_nO_{2n}F_2 with n=2,3,4, where n is the number of CuO_2 planes. It is revealed that bi-layered Ba_2CaCu_2O_4F_2 is an underdoped superconductor with hole carriers, which are introduced into CuO_2 planes by an unexpected deviation from the nominal content of apical fluorines. In a previous paper, we proposed a self-doping mechanism as the origin of carrier doping in n=3 and n=4; in the mechanism, electrons are transferred from the inner CuO_2 plane (IP) to the outer one (OP). However, since it has been found that the bi-layered compound is hole doped, we have reexamined the superconducting and magnetic properties in n=3 and n=4 by Cu-NMR/NQR and F-NMR. The extensive NMR studies have confirmed that the apical-fluorine compounds are not self-doped but hole-doped, and that antiferromagnetism (AFM) and superconductivity (SC) coexist in a single CuO_2 plane. In n=4, the AFM ordering occurs at T_N = 80 K, well above T_c=55 K, where the respective AFM moments are M_AFM=0.11 mu_B and 0.18 mu_B at the OP and the IP. In n=3, on the other hand, the underdoped single IP exhibits a spontaneous moment M_AFM=0.12 mu_B at low temperatures and a peak in the nuclear-spin-lattice relaxation rate 1/T_1 of F at T_N=23 K, much lower than T_c = 76 K. We note that the increase in the number of IPs from one to two leads to an increase in T_N due to strengthening the interlayer coupling, although the doping levels for both compounds are almost comparable. The present results strongly suggest that the uniform mixing of AFM and SC is a general property inherent to a single CuO_2 plane in the underdoped regime for hole-doping.
description: 9 pages, 9 figures, to be published in Phys. Rev. B, volume 79, Issue 2 (2009)
Energy Transport in an Ising Disordered Model
Creators: name: Agliari, Elena
name: Casartelli, Mario
name: Vezzani, Alessandro
Publisher: name: arXiv
Year: 2009
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We introduce a new microcanonical dynamics for a large class of Ising systems isolated or maintained out of equilibrium by contact with thermostats at different temperatures. Such a dynamics is very general and can be used in a wide range of situations, including disordered and topologically inhomogenous systems. Focusing on the two-dimensional ferromagnetic case, we show that the equilibrium temperature is naturally defined, and it can be consistently extended as a local temperature when far from equilibrium. This holds for homogeneous as well as for disordered systems. In particular, we will consider a system characterized by ferromagnetic random couplings $J_{ij} \in [ 1 - ε, 1 + ε]$. We show that the dynamics relaxes to steady states, and that heat transport can be described on the average by means of a Fourier equation. The presence of disorder reduces the conductivity, the effect being especially appreciable for low temperatures. We finally discuss a possible singular behaviour arising for small disorder, i.e. in the limit $ε\to 0$.
description: 14 pages, 8 figures
Magnetic Properties of the Metamagnet Ising Model in a three-dimensional Lattice in a Random and Uniform Field
Creators: name: Santos-Filho, J. B. dos
name: de Albuquerque, Douglas F.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: By employing the Monte Carlo technique we study the behavior of Metamagnet Ising Model in a random field. The phase diagram is obtained by using the algorithm of Glaubr in a cubic lattice of linear size $L$ with values ranging from 16 to 42 and with periodic boundary conditions.
description: 4 pages, 6 figures
Raman scattering of perovskite DyScO3 and GdScO3 single crystals
Creators: name: Chaix-Pluchery, O.
name: Kreisel, J.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We report an investigation of DyScO3 and GdScO3 single crystals by Raman scattering in various scattering configurations and at various wavelengths. The Raman spectra are well-defined and the reported spectral signature together with the mode assignment sets the basis for the use of Raman scattering for the investigation of RE-scandates. The observed positions of Raman modes for DyScO3 are for most bands in reasonable agreement with recent theoretical ab initio predictions of the vibrational spectrum for the same material. Further to the phonon signature, a luminescence signal is observed for both scandates. While the luminescence is weak for DyScO3, it is very intense for GdScO3 when using a 488 or 514 nm excitation line, which in turn inhibits full analysis of the phonon spectrum. We show that a meaningful phonon Raman analysis of GdScO3 samples can be done by using a 633 nm excitation.
On the global maximum of the solution to a stochastic heat equation with compact-support initial data
Creators: name: Foondun, Mohammud
name: Khoshnevisan, Davar
Publisher: name: arXiv
Year: 2009
Subjects: subject: Probability (math.PR)
subject: FOS: Mathematics
subject: 35R60, 37H10, 60H15

description: Consider a stochastic heat equation $\partial_t u = κ\partial^2_{xx}u+σ(u)\dot{w}$ for a space-time white noise $\dot{w}$ and a constant $κ>0$. Under some suitable conditions on the the initial function $u_0$ and $σ$, we show that the quantity \limsup_{t\to\infty}t^{-1}\ln\E(\sup_{x\in\R} |u_t(x)|^2) is bounded away from zero and infinity by explicit multiples of $1/κ$. Our proof works by demonstrating quantitatively that the peaks of the stochastic process $x\mapsto u_t(x)$ are highly concentrated for infinitely-many large values of $t$. In the special case of the parabolic Anderson model--where $σ(u)= λu$ for some $λ>0$--this "peaking" is a way to make precise the notion of physical intermittency.
Five Long-period Extrasolar Planets in Eccentric orbits from the Magellan Planet Search Program
Creators: name: Arriagada, Pamela
name: Butler, R. Paul
name: Minniti, Dante
name: Lopez-Morales, Mercedes
name: Shectman, Stephen A.
name: Adams, Fred C.
name: Boss, Alan P.
name: Chambers, John E.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: Five new planets orbiting G and K dwarfs have emerged from the Magellan velocity survey. These companions are jovian-mass planets in eccentric (e \geq 0.24) intermediate and long-period orbits. HD 86226b orbits a solar metallicity G2 dwarf. The MP sin i mass of the planet is 1.5 MJUP, the semi-major axis is 2.6 AU, and the eccentricity 0.73. HD 129445b orbits a metal rich G6 dwarf. The minimum mass of the planet is MP sin i =1.6 MJUP, the semi-major axis is 2.9 AU, and the eccentricity 0.70. HD 164604b orbits a K2 dwarf. The MP sin i mass is 2.7 MJUP, semi-major axis is 1.3 AU, and the eccentricity is 0.24. HD 175167b orbits a metal rich G5 star. The MP sin i mass is 7.8 MJUP, the semi-major axis is 2.4 AU, and the eccentricity 0.54. HD 152079b orbits a G6 dwarf. The MP sin i mass of the planet is 3 MJUP, the semi-major axis is 3.2 AU, and the eccentricity is 0.60.
description: Accepted for publication on ApJ, 27 pages, 9 figures
On the central core in MHD winds and jets
Creators: name: Beskin, V. S.
name: Nokhrina, E. E.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We demonstrate that the 1D cylindrical version of the Grad-Shafranov equation is more rich than classical self-similar ones, and more suitable for the astrophysical jets we observe. In particular, it allows us to describe the central (and, hence, the most energetic) part of the flow. Both relativistic and non-relativistic versions are discussed. It is shown that taking into account the finite pressure of the external media one can determine the magnetic flux within the central core. We found as well that for non-relativistic flows which are magnetically dominated near the origin the solution can be constructed only in the presense of the oblique shock near the base of a jet where the additional heating is to take place.
description: 8 pages, 3 figures The typoes in the Fig.1 and Fig.3 have been corrected
Annotation-Based Analysis of Religious Metaphors in German Medieval Texts
Creators: name: Wiemann, Alexandra
Publisher: name: Department of Digital Humanities, University of Graz
Year: 2024
Subjects: subject: Textual Analysis
subject: Dependency Parsing
subject: Digital humanities
subject: Medieval history
subject: German

description: Religious meaning-making occurs in and through metaphors. Religion depends on them, as it can never articulate its ultimate object, namely the transcendental, literally. The CRC 1475 aims to understand this process with greater theoretical precision and grasp it methodically, in order to empirically and comparatively research the semantic formation of religion.
Higher moments of charge fluctuations in QCD at high temperature
Creators: name: Miao, C.
Publisher: name: arXiv
Year: 2009
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: We present lattice results for baryon number, strangeness and electric charge fluctuations as well as their correlations at finite temperature and vanishing chemical potentials, i.e. under conditions relevant for RHIC and LHC. We find that the fluctuations change rapidly at the transition temperature $T_c$ and approach the ideal quark gas limit already at approximately $1.5T_c$. This indicates that quarks are the relevant degrees of freedom that carry the quantum numbers of conserved charges at $T\geq 1.5T_c$. At low temperature, qualitative features of the lattice results are well described by a hadron resonance gas model.
description: 4 pages, 3 figures - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennessee
Evolution of Cluster of Stars in f(R) Gravity
Creators: name: Manzoor, Rubab
name: Shahid, Wasee
Publisher: name: arXiv
Year: 2021
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: This paper explores the dynamics of evolving cluster of stars in the presences of exotic matter. The $f(R)$ theory is used to presume exotic terms for evolution scenario. We use structure scalars as evolution parameters to explore dynamics of spherically symmetric distribution of evolving cluster of stars. We consider Starobinsky model, $f(R)=R+εR^2$ and study different evolution modes having features like isotropic pressure, density homogeneity, homologous and geodesic behavior. It is concluded that dynamics of these modes of evolution depends upon the behavior of dark matter. The presences of dark matter directly affects the features of cluster like anisotropic pressure, dissipation, expansion, shear as well as density homogeneity. The evolution having homogeneous density and isotropic pressure depends upon conformally flat and non-dissipative behavior of baryonic as well as non baryonic matter. The dissipation factor induces density inhomogeneity in the expanding clusters having shear effects. The non dissipative homologous evolution also be discussed in the presence and absence of shear effects. It is found that high curvature geometry in the presence of shear supports homologous evolution. Expanding clusters are also explored in the presences of dissipation of dark matter and shear effects. By using quasi-homologous conditions the geodesic evolution is studied. It is theoretically showed that geodesic and homologous conditions depends upon each other. Finally we investigate behavior of Starobinsky model for a stellar structure $4U 1820-30$ toward center. It is found that for increasing values of $ε$ the DM behavior is dominant as compare to baryonic matter.
Numerical analysis of seismic wave amplification in Nice (France) and comparisons with experiments
Creators: name: Semblat, Jean-François
name: Duval, Anne-Marie
name: Dangla, Patrick
Publisher: name: arXiv
Year: 2009
Subjects: subject: Classical Physics (physics.class-ph)
subject: FOS: Physical sciences

description: The analysis of site effects is very important since the amplification of seismic motion in some specific areas can be very strong. In this paper, the site considered is located in the centre of Nice on the French Riviera. Site effects are investigated considering a numerical approach (Boundary Element Method) and are compared to experimental results (weak motion and microtremors). The investigation of seismic site effects through numerical approaches is interesting because it shows the dependency of the amplification level on such parameters as wave velocity in surface soil layers, velocity contrast with deep layers, seismic wave type, incidence and damping. In this specific area of Nice, a one-dimensional (1D) analytical analysis of amplification does not give a satisfactory estimation of the maximum reached levels. A boundary element model is then proposed considering different wave types (SH, P, SV) as the seismic loading. The alluvial basin is successively assumed as an isotropic linear elastic medium and an isotropic linear viscoelastic solid (standard solid). The thickness of the surface layer, its mechanical properties, its general shape as well as the seismic wave type involved have a great influence on the maximum amplification and the frequency for which it occurs. For real earthquakes, the numerical results are in very good agreement with experimental measurements for each motion component. Two-dimensional basin effects are found to be very strong and are well reproduced numerically.
Hidden electronic phase in strained few-layer 1T-TaS2
Creators: name: S, Sruthi
name: Kundu, Hemanta Kumar
name: Vishnubhotla, Prasad
name: Bid, Aveek
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Layered van der Waals materials are exciting as they often host multiple, competing electronic phases. This article reports experimental observation of the co-existence of insulating and metallic phases deep within the commensurate charge density wave phase in high-quality devices of few-layer 1T-TaS2. Through detailed conductance fluctuation spectroscopy of the electronic ground state, we establish that the mixed-phase consists of insulating regions surrounded by one-dimensional metallic domain walls. We show that the electronic ground state of 1T-TaS2 can be affected drastically by strain, eventually leading to the collapse of the Mott gap in the commensurate charge density wave phase. Our study resolves an outstanding question, namely the effect of the inter-layer coupling strength on the electronic phases in layered van der Waals materials.
description: 7 pages, 6 figures
Mapping the Dirac point in gated bilayer graphene
Creators: name: Deshpande, A.
name: Bao, W.
name: Zhao, Z.
name: Lau, C. N.
name: LeRoy, B. J.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We have performed low temperature scanning tunneling spectroscopy measurements on exfoliated bilayer graphene on SiO2. By varying the back gate voltage we observed a linear shift of the Dirac point and an opening of a band gap due to the perpendicular electric field. In addition to observing a shift in the Dirac point, we also measured its spatial dependence using spatially resolved scanning tunneling spectroscopy. The spatial variation of the Dirac point was not correlated with topographic features and therefore we attribute its shift to random charged impurities.
description: 3 pages, 3 figures
Social Networks and Prosopography of 12th-Century Byzantium
Creators: name: Vlachou, Olga
Publisher: name: Department of Digital Humanities, University of Graz
Year: 2024
Subjects: subject: Social Networks
subject: Prosopography
subject: Digital humanities
subject: Medieval history

description: This dissertation aims to reconstruct and analyze the social networks of 12th-century Byzantium, approximately from the reign of Manuel I Komnenos to the Latin capture of Constantinople (1143-1204), and conduct a prosopographical study of its members using the extant letters of contemporary authors as primary sources.
HP-GNN: Generating High Throughput GNN Training Implementation on CPU-FPGA Heterogeneous Platform
Creators: name: Lin, Yi-Chien
name: Zhang, Bingyi
name: Prasanna, Viktor
Publisher: name: arXiv
Year: 2021
Subjects: subject: Distributed, Parallel, and Cluster Computing (cs.DC)
subject: FOS: Computer and information sciences

description: Graph Neural Networks (GNNs) have shown great success in many applications such as recommendation systems, molecular property prediction, traffic prediction, etc. Recently, CPU-FPGA heterogeneous platforms have been used to accelerate many applications by exploiting customizable data path and abundant user-controllable on-chip memory resources of FPGAs. Yet, accelerating and deploying GNN training on such platforms requires not only expertise in hardware design but also substantial development efforts. We propose HP-GNN, a novel framework that generates high throughput GNN training implementations on a given CPU-FPGA platform that can benefit both application developers and machine learning researchers. HP-GNN takes GNN training algorithms, GNN models as the inputs, and automatically performs hardware mapping onto the target CPU-FPGA platform. HP-GNN consists of: (1) data layout and internal representation that reduce the memory traffic and random memory accesses; (2) optimized hardware templates that support various GNN models; (3) a design space exploration engine for automatic hardware mapping; (4) high-level application programming interfaces (APIs) that allows users to specify GNN training with only a handful of lines of code. To evaluate HP-GNN, we experiment with two well-known sampling-based GNN training algorithms and two GNN models. For each training algorithm and model, HP-GNN generates implementation on a state-of-the-art CPU-FPGA platform. Compared with CPU-only and CPU-GPU platforms, experimental results show that the generated implementations achieve $55.67\times$ and $2.17\times$ speedup on the average, respectively. Compared with the state-of-the-art GNN training implementations, HP-GNN achieves up to $4.45\times$ speedup.
Signature of cool cores in SZ clusters: a multiwavelength approach
Creators: name: Pipino, A.
name: Pierpaoli, E.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We use the high quality pressure profiles of 239 galaxy clusters made available by the ACCEPT project (Cavagnolo et al. 2009) in order to derive the expected Sunyaev Zeldovich (SZ) signal in a variety of cases that hardly find a counterpart in the simulations. We made use of the Melin et al. (2006) cluster selection function for both the South Pole Telescope (SPT) and Planck instruments. We infer a clear effect of the cool core (CC) on the central Compton parameter y_0. We find that the presence of CCs introduces a small bias in cluster detection, especially around the mass at which the performance of the survey begins to decrease. If the CC were removed, a lower overall fraction of detected clusters would be expected. In order to estimate the presence of such a bias by means of SZ only surveys, we show that the ratio between y_0 and y_int anti-correlates with the cluster central cooling time. If multi-band optical cluster surveys are either available for a cross-match or a follow-up is planned, we suggest that likely CC clusters are those with a Brightest Cluster Galaxy (BCG) at least 0.3 magnitudes bluer than the average. A more robust estimate of the CC presence is given by UV-optical colours of the BCG, like the NUV-r, whose values can be 4 magnitudes off the NUV-r equivalent of the red sequence, in clusters with low excess entropy. We also find correlation of the y_0/y_int ratio with Halpha, IR and radio luminosities. We argue that the analysis of a combined SZ/optical/UV surveys can be also used to shed light on the suggested CC evolution with redshift. (abridged)
description: 16 pages, 13 figures, MNRAS accepted