Miracle-dz/UniFAR-FTUs huggingface dataset:
Van der Waals interlayer potential of graphitic structures: From Lennard–Jones to Kolmogorov–Crespy and Lebedeva models

The experimental knowledge on interlayer potential of graphitic materials is summarized and compared with the computational results based on phenomenological models. Besides Lennard–Jones approximation, the Mie potential is discussed, as well as the Kolmogorov–Crespy model and equation of Lebedeva et al. An agreement is found between a set of reported physical properties of graphite (layer binding energies, compressibility along c-axis in a broad pressure range, Raman frequencies for bulk shear and breathing modes under pressure), when a proper choice of model parameters is taken. It is argued that anisotropic potentials, Kolmogorov–Crespy and Lebedeva, are preferable for modeling, as they provide a better, self-consistent description. A method of fast numerical modeling, convenient for the accurate estimation of the discussed physical properties, is proposed. It may be useful in studies of other van der Waals homo/heterostructures as well.
Lorenz model for the rotating Rayleigh-Bernard problem

A four-mode Lorenz model for the rotating Rayleigh-Benard system is constructed which reproduces the results of a linear stability analysis of the hydrodynamic equations. An extension of this model predicts that the Kuppers-Lortz instability occurs at a critical Taylor number of Tc=80 pi 4 and a critical angle theta c given by tan theta c/4= square root 5.
Causal order as a resource for quantum communication

In theories of communication, it is usually presumed that the involved parties perform actions in a fixed causal order. However, practical and fundamental reasons can induce uncertainties in the causal order. Here we show that a maximal uncertainty in the causal order forbids asymptotic quantum communication, while still enabling the noisy transfer of classical information. Therefore causal order, like shared entanglement, is an additional resource for communication. The result is formulated within an asymptotic setting for processes with no fixed causal order, which sets a basis for a quantum information theory in general quantum causal structures.
Resolved polarization changes across H alpha in the classical T Tauri star RY Tauri

We present linear H α spectropolarimetry of the classical T Tauri star RY Tau. A change in the polarization percentage and position angle across H α is detected, which suggests that line photons are scattered in a rotating disc. We derive the position angle from the slope of the loop in the $(Q,U)$ diagram and find it to be 146 ± 3 o . This is perpendicular to the position angle of the disc of 48 ± 5 o as deduced from millimeter imaging by Koerner & Sargent ([CITE]). This finding is consistent, as scattering off the imaged millimeter disc is expected to yield a polarization signature in a direction that is rotated by 90 o from this disc. The observed spectropolarimetric behaviour of RY Tau is reminiscent of that seen in a large group of Herbig Ae stars, suggesting a common circumstellar origin of the polarized photons.
GEMS: Galaxy Evolution from Morphologies and SEDs

GEMS (Galaxy Evolution from Morphologies and SEDs) is a large-area (800 arcmin2) two-color (F606W and F850LP) imaging survey with the Advanced Camera for Surveys on the Hubble Space Telescope. Centered on the Chandra Deep Field-South, it covers an area of ~28′ × 28′, or about 120 Hubble Deep Field areas, to a depth of mAB(F606W) = 28.3(5 σ) and mAB(F850LP) = 27.1(5 σ) for compact sources. In its central ~1/4, GEMS incorporates ACS imaging from the GOODS project. Focusing on the redshift range 0.2 ≲ z ≲ 1.1, GEMS provides morphologies and structural parameters for nearly 10,000 galaxies where redshift estimates, luminosities, and SEDs exist from COMBO-17. At the same time, GEMS contains detectable host galaxy images for several hundred faint active galactic nuclei. This paper provides an overview of the science goals, the experiment design, the data reduction, and the science analysis plan for GEMS.
Parameterization of Stillinger-Weber Potential for Two- Dimensional Atomic Crystals

We parametrize the Stillinger-Weber potential for 156 two-dimensional atomic crystals. Parameters for the Stillinger-Weber potential are obtained from the valence force field model following the analytic approach (Nanotechnology 26, 315706 (2015)), in which the valence force constants are determined by the phonon spectrum. The Stillinger-Weber potential is an efficient nonlinear interaction, and is applicable for numerical simulations of nonlinear physical or mechanical processes. The supplemental resources for all simulations in the present work are available online in Ref. 1, including a fortran code to generate crystals' structures, files for molecular dynamics simulations using LAMMPS, files for phonon calculations with the Stillinger-Weber potential using GULP, and files for phonon calculations with the valence force field model using GULP.
Critical Ising Model and Cycle Rooted Spanning Forests: an explicit correspondence

Fisher established an explicit correspondence between the 2-dimensional Ising model defined on a graph $G$ and the dimer model defined on a decorated version $\GD$ of this graph \cite{Fisher}. In this paper, we prove an explicit correspondence between the dimer model associated to a large class of critical Ising models whose underlying graph is periodic, and critical cycle rooted spanning forests (CRSFs). The correspondence is established through characteristic polynomials, whose definition only depends on the respective fundamental domains, and which encode the combinatorics of the models. We first show a matrix-tree type theorem establishing that the dimer characteristic polynomial counts CRSFs of the decorated fundamental domain $\GD_1$. Our main result consists in an explicit, weight preserving correspondence between CRSFs of $\GD_1$ counted by the dimer characteristic polynomial and CRSFs of $G_1$, where edges are assigned Kenyon's critical weight function \cite{Kenyon3}.
Compact spherical coil for fluxgate magnetometer vector feedback

A novel design of a magnetic field feedback compensation coil system for triaxial fluxgate magnetometers is presented. The coils are wound on three concentric spherical shells of slightly different diameters with the fluxgate sensors placed in the 60 mm diameter internal field-free space. Measurements of the temperature coefficient and of the internal field homogeneity are given, and the noise performance is evaluated for a magnetometer incorporating the coil. The total outer diameter of the system is 90 mm and the weight is 350 g including the sensors. The main advantage of a vector feedback system is the exact definition of the magnetic axes. These are determined exclusively by the coil axes, and they are independent of even large angular displacements of the individual magnetic axes of the fluxgate elements.
Primordial trispectrum from inflation

We use the delta N-formalism to describe the leading order contributions tothe primordial power spectrum, bispectrum and trispectrum in multiple-fieldmodels of inflation at leading order in a perturbative expansion. In slow-rollmodels where the initial field fluctuations at Hubble-exit are nearly Gaussian,any detectable non-Gaussianity is expected to come from super-Hubble evolution.We show that the contribution to the primordial trispectrum can be described bytwo non-linearity parameters, tau_{NL} and g_{NL}, which are dependent upon thesecond and third derivatives of the local expansion with respect to the fieldvalues during inflation.
Scalings for ultra-relativistic laser plasmas and monoenergetic electrons

The similarity theory is derived for ultra-relativistic laser-plasma interactions. First, it is shown that the most fundamental S − similarity is valid for both under- and overdense plasmas. Then, the particular case of tenious plasma is considered in great detail. It is shown that the electron dynamics in this case has two characteristic scales. The fast scale corresponds to relaxation to some attractor solution. The slow dynamics describes an adiabatic evolution of this attractor. This leads to a remarkable wave breaking exclusion rule in the 3 D geometry. A similarity theory for the slow dynamics allows obtaining simple “engineering” scalings for the maximum electron energies, the number of accelerated electrons, the electron beam density, and for the acceleration distance. These scalings are aimed at design of a high-energy laser-plasma accelerator generating electron beams with superior properties.
Search for quasi-periodic signals in magnetar giant flares

Quasi-periodic oscillations (QPOs) discovered in the decaying tails of giant flares of magnetars are believed to be torsional oscillations of neutron stars. These QPOs have a high potential to constrain properties of high-density matter. In search for quasi-periodic signals, we study the light curves of the giant flares of SGR 1806-20 and SGR 1900+14, with a non-parametric Bayesian signal inference method called D$^3$PO. The D$^3$PO algorithm models the raw photon counts as a continuous flux and takes the Poissonian shot noise as well as all instrument effects into account. It reconstructs the logarithmic flux and its power spectrum from the data. Using this fully noise-aware method, we do not confirm previously reported frequency lines at $\nu\gtrsim17\,$Hz because they fall into the noise-dominated regime. However, we find two new potential candidates for oscillations at $9.2\,$Hz (SGR 1806-20) and $7.7\,$Hz (SGR 1900+14). If these are real and the fundamental magneto-elastic oscillations of the magnetars, current theoretical models would favour relatively weak magnetic fields $\bar B\sim 6\times10^{13} - 3\times10^{14}\,$G (SGR 1806-20) and a relatively low shear velocity inside the crust compared to previous findings.
Nonlinear optics with ZnO nanowires

Second‐harmonic generation and two‐photon induced photoluminescence from arrays of ZnO nanowires and single nanowires under excitation with femtosecond pulses is experimentally studied. The ratio of relevant components of the nonlinear χ(2) tensor is obtained. The excitation of the nanowire array with femtosecond laser pulses induces significant heating of the free‐standing nanowires. The heat distribution is analyzed in phenomenological finite‐element studies. Two‐photon excitation of a broad internal photoluminescence in single ZnO nanowires is used to perform a single‐nanowire transmission experiment. From the transmitted intensity, the band‐gap shift in the excited nanowire is obtained. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A sample of metal-poor galaxies identified from the LAMOST spectral survey

We present a sample of 48 metal-poor galaxies at z<0.14 selected from 92 510 galaxies in the LAMOST survey. These galaxies are identified by their detection of the auroral emission line [OIII]λ4363 above the 3σ level, which allows a direct measurement of electron temperature and oxygen abundance. The emission line fluxes are corrected for internal dust extinction using the Balmer decrement method. With electron temperature derived from [OIII]λλ4959,5007/[OIII]λ4363 and electron density from [SII]λ6731/[SII]λ6717, we obtain the oxygen abundances in our sample which range from 12+log(O/H)=7.63(0.09Z⊙) to 8.46 (0.6Z⊙). We find an extremely metal-poor galaxy with 12+log(O/H)=7.63±0.01. With multiband photometric data from FUV to NIR and Hα measurements, we also determine the stellar masses and star formation rates, based on the spectral energy distribution fitting and Hα luminosity, respectively. We find that our galaxies have low and intermediate stellar masses with 6.39≤log(M/M⊙)≤9.27, and high star formation rates (SFRs) with −2.18≤log(SFR/M⊙yr−1)≤1.95. We also find that the metallicities of our galaxies are consistent with the local Te-based mass–metallicity relation, while the scatter is about 0.28 dex. Additionally, assuming the coefficient of α=0.66, we find most of our galaxies follow the local mass–metallicity–SFR relation, but a scatter of about 0.24 dex exists, suggesting the mass–metallicity relation is weakly dependent on SFR for those metal-poor galaxies.
"Faster Than Light" Photons in Dilaton Black Hole Spacetimes

We investigate the phenomenon of "faster than light" photons in a family of dilaton black hole spacetimes. For radially directed photons, we find that their light-cone condition is modified even though the spacetimes are spherically symmetric. They also satisfy the "horizon theorem" and the "polarization sum rule" of Shore. For orbital photons, the dilatonic effect on the modification of the light-cone condition can become more dominant than the electromagnetic and the gravitational ones as the orbit gets closer to the event horizon in the extremal or near-extremal cases.
Unique optical properties of AlGaN alloys and related ultraviolet emitters

Deep UV photoluminescence spectroscopy has been employed to study the optical properties of AlxGa1−xN alloys (0⩽x⩽1). The emission intensity with polarization of E⊥c and the degree of polarization were found to decrease with increasing x. This is a consequence of the fact that the dominant band edge emission in GaN (AlN) is with polarization of E⊥c(E∥c). Our experimental results suggest that the decreased emission efficiency in AlxGa1−xN alloys and related UV emitters could also be related with their unique polarization property, i.e., the intensity of light emission with polarization of E⊥c decreases with x. It is thus concluded that UV emitters with AlGaN alloys as active layers have very different properties from InGaN and other semiconductor emitters.
Simple algorithms to calculate asymptotic null distributions of robust tests in case-control genetic association studies in R

The case-control study is an important design for testing association between genetic markers and a disease. The Cochran-Armitage trend test (CATT) is one of the most commonly used statistics for the analysis of case-control genetic association studies. The asymptotically optimal CATT can be used when the underlying genetic model (mode of inheritance) is known. However, for most complex diseases, the underlying genetic models are unknown. Thus, tests robust to genetic model misspecification are preferable to the model-dependant CATT. Two robust tests, MAX3 and the genetic model selection (GMS), were recently proposed. Their asymptotic null distributions are often obtained by Monte-Carlo simulations, because they either have not been fully studied or involve multiple integrations. In this article, we study how components of each robust statistic are correlated, and find a linear dependence among the components. Using this new finding, we propose simple algorithms to calculate asymptotic null distributions for MAX3 and GMS, which greatly reduce the computing intensity. Furthermore, we have developed the R package Rassoc implementing the proposed algorithms to calculate the empirical and asymptotic p values for MAX3 and GMS as well as other commonly used tests in case-control association studies. For illustration, Rassoc is applied to the analysis of case-control data of 17 most significant SNPs reported in four genome-wide association studies.
Tidal disruption events can power the observed AGN in dwarf galaxies

In recent years, numerous active galactic nuclei have been discovered in ever smaller galaxies, questioning the paradigm that dwarf galaxies do not harbour central massive black holes. Even if such black holes exist, feeding them by gas streams is difficult, since star formation should be more efficient than AGN feeding in dwarf galaxies. In this paper, I investigate the possibility that tidal disruptions of stars are responsible for the observed AGN in dwarf galaxies. I show that the expected duty cycles of TDE-powered AGN, $f_{\rm AGN} \geq 0.5\%$, are consistent with observed AGN fractions assuming that the occupation fraction in dwarf galaxies is close to unity. Furthermore, I calculate the properties of outflows driven by TDE-powered AGN under idealised conditions and find that they might have noticeable effects on the host galaxies. Outflows themselves might not be detectable, except in gas-poor galaxies, where they can accelerate to $v_{\rm out} > 100$~km/s, but increased gas turbulence, more diffuse density profile and lower star formation efficiency can be discovered and used to constrain the black hole occupancy fraction and more nuanced effects on dwarf galaxy evolution. If massive black holes form from seeds that are much more massive than stellar black holes, then their outflows should be easily detectable; this result, aided by observations of high-redshift dwarf galaxies, provides a potential way of determining seed masses of black holes.
The small dispersion of the mid IR - hard X-ray correlation in active galactic nuclei

Context. We investigate mid-infrared and X-ray properties of the dusty torus in unification scenarios for active galactic nuclei. Aims. We use the relation between mid IR and hard X-ray luminosities to constrain AGN unification scenarios. Methods. With VISIR at the VLT, we have obtained the currently highest angular resolution ($0 \farcs 35$ FWHM ) narrow-band mid infrared images of the nuclei of 8 nearby Seyfert galaxies. Combining these observations with X-ray data from the literature we study the correlation between their mid IR and hard X-ray luminosities. Results. We find that the rest frame $12.3 \, \mu$m ($L_{\mathrm{MIR}}$) and 2–10 keV ($L_{\mathrm{X}}$) luminosities are correlated at a highly significant level. The best fit power-law to our data is $\log{L_{\mathrm{MIR}}} \propto \left(1.60 \pm 0.22 \right) \log{L_{\mathrm{X}}}$, showing a much smaller dispersion than earlier studies. Conclusions. The similarity in the $\log{L_{\mathrm{MIR}}}$/$\log{L_{\mathrm{X}}}$ ratio between Sy1s and Sy2s even using high angular resolution MIR data implies that the similarity is intrinsic to AGN and not caused by contamination from extra-nuclear emission. This supports clumpy torus models. The exponent of the correlation constrains the inner geometry of the torus.
Search for the Standard Model Higgs boson at LEP

The combined results of the search for the Standard Model Higgs boson from the four LEP experiments are given. These results are based on the full data sample collected by ALEPH, DELPHI, L3 and OPAL at centre-of-mass energies up to 209GeV, corresponding to a total integrated luminosity of about 2.5fb-1. A slight excess of events over the background expectation is found at the 2sigma level, originating mainly from the ALEPH 4-jet channel. This excess is compatible with what expected for the production of a SM Higgs boson with a mass of 115.6GeV/c2. A combined 95% confidence level lower limit of 114.1GeV/c2 on the mass of the Standard Model Higgs boson is derived.
Third and fourth Stokes parameters in polarimetric passive microwave remote sensing of rough surfaces over layered media

We consider the four Stokes parameters in microwave emission from a layered medium with the top interface being a rough surface. The rough surface varies in one horizontal direction so that azimuthal asymmetry exists in the 3‐D problem. Dyadic Green's functions of multilayered media are used to formulate the surface integral equations. Periodic boundary conditions are used. The numerical results show that the presence of the layered media below the rough surface reduces the vertical and horizontal brightness temperatures. The interaction between the rough surface and the layered media also enhance the third and fourth Stokes parameters. In particular, the fourth Stokes parameter can be large for such geometrical configurations. Results show that the nonzero third and fourth Stokes parameters exist for all frequencies and are particularly large when the rough surface has large slope. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3063–3069, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23892
Microsegregation effects on the thermal conductivity of silicon-germanium alloys

A silicon-germanium (SiGe) alloy is a promising candidate for thermoelectric materials; while it shows a significantly reduced thermal conductivity (κ) as compared to pure Si and Ge, the κ values obtained from previous experiments and computations tend to be widely scattered. We present here a computational analysis of thermal transport in SiGe, particularly the effects of the local segregation (microsegregation) of alloying elements. Our nonequilibrium molecular dynamics simulations confirm the strong dependence of κ on the Si:Ge ratio and the occurrence of the minimum κ around Si0.8Ge0. 2, consistent with existing experimental observations. Moreover, our study clearly demonstrates that the κ of Si0.8Ge0. 2 increases substantially and monotonically as Ge atoms undergo segregation; that is, the magnitude of alloy scattering is found to be sensitive to homogeneity in the distribution of alloying elements. Nonequilibrium Green's function analysis also shows that such microsegregation enhances phonon transmiss.
Large-scale structure in the ELAIS S1 Survey

We present an analysis of the two-point angular correlation function of The European Large-Area Infrared Space Observatory (ELAIS) S1 survey. The survey covers 4 deg2 and contains 462 sources detected at 15 mum to a 5sigma flux limit of 0.45 mJy. Using the 329 extragalactic sources not repeated in different observations, we detect a significant clustering signal; the resulting angular correlation function can be fitted by a power law w(theta) =Atheta1-gamma with A= 0.014 +/- 0.005 and gamma= 2.04 +/- 0.18. Using the observed redshift distribution of the objects (from spectroscopic and photometric redshifts), we invert Limber's equation and deduce a spatial correlation length r0= 4.3+0.4-0.7h-1 Mpc. This is smaller than that obtained from optical surveys but it is in agreement with results from IRAS. This extends to higher redshift the observational evidence that infrared selected surveys show smaller correlation lengths (i.e. reduced clustering amplitudes) than optical surveys.
Precision Determination of the Mass Function of Dark Matter Halos

The predicted mass function of dark matter halos is essential in connecting observed galaxy-cluster counts and models of galaxy clustering to the properties of the primordial density field. We determine the mass function in the concordance ΛCDM cosmology, as well as its uncertainty, using sixteen 10243 particle nested-volume dark matter simulations spanning a mass range of over 5 orders of magnitude. Using the nested volumes and single-halo tests, we find and correct for a systematic error in the friends-of-friends halo-finding algorithm. We find a fitting form and full error covariance for the mass function that successfully describes the simulations' mass function and is well behaved outside the simulations' resolutions. Estimated forecasts of uncertainty in cosmological parameters from future cluster-count surveys receive a negligible contribution from remaining statistical uncertainties in the central cosmology multiplicity function. There exists a potentially nonnegligible cosmological dependence (nonuniversality) of the halo multiplicity function.