Miracle-dz/UniFAR-FTUs huggingface dataset:
Spectra of cometary X rays induced by solar wind ions

The X-ray and extreme ultraviolet spectra produced by solar wind ions undergoing change transfer collisions with the atoms and molecules present in the atmospheres of comets are calculated. The calculations take account of the cascading transitions that follow electron capture into highly excited states. It is shown that sequential collisions cause the X-ray spectrum from the cometary center to be softer than that of the peripheral regions. Some of the brightest lines arise from forbidden transitions of helium-like oxygen and carbon ions. The X-ray luminosities and averaged spectra reflect the composition of the solar wind. The calculated luminosities and spectra corresponding to a typical distribution of impinging solar wind ions are consistent with observations of comets Hyakutake and Hale-Bopp. The spectral resolution required to establish charge transfer as the source of cometary X rays is discussed; an energy resolution of 10 eV should be adequate.
Nonlinear Analysis of Smart Composite Plates Including Hysteresis Effects

The coupled electrothermoelastic constitutive relations, representing the behavior of piezo materials, are shown to be nonlinear when the polarization―electric field interaction effects are properly accounted for. Under static condition, the polarization―electric field nonlinearities correspond to a distributed body force and body moment. For time varying situations, polarization―electric field interaction exhibits a hysteresis effect. Using the nonlinear constitutive relations, a layer-by-layer finite element formulation is developed for both static and dynamic analyses of smart plates including hysteresis effects. Linear and nonlinear analyses are carried out to study the effect of nonlinearity due to polarization―electric field interaction on the response of the smart plates. To validate the present formulation, the results of static analysis of a smart plate are compared with experimental data available in literature. It is observed that the P-E hysteresis effects show a friction-type damping in the dynamic response of the smart plate.
Model images of radio halos around supernova remnants

I present model calculations of profiles and two-dimensional images of the radio synchrotron emission of young supernova remnants, concentrating on observable effects of relativistic eletrons diffusing upstream of the shock wave. If the preshock electron scattering mean free path is sufficiently long, observable synchrotron halos outside the bulk of the radio emission can potentially result; their absence can constrain the mean free path from above. If scattering is primarily due, as expected, to Alfven waves with amplitude detla(B), the halo is expected to extend a distance of order r(sub g)c(delta(B)/B)(exp 2)/v(sub s) beyond the shock, where r(sub g) is the gyroradius of the electrons emitting at the observed frequency, B is the upstream magnetic field strength, v(sub s) is the shock velocity, and the amplitude delta(B) refers to wave with wavelength comparable to r(sub g), of order 10(exp 13) cm for typical supernova-remnant parameters. However, the detailed geometry of the halo varies with the assumptions about particle acceleration in the shock wave. I present an atlas of model profiles and images as a function of preshock diffusion length, of aspect angle between the magnetic field and the line of sight, and of other relevant parameters.
Properties of the Optical Quantum Amplifier

The properties of a linear optical amplifier or attenuator in which the input light is coupled to a collection of non-saturable atoms are considered. The photon-number factorial moments and probability distribution of the amplifier output are derived for arbitrary input statistics. Relations are obtained between the output and input variances in photon number, phase-angle cosine, and electric-field magnitude. The effects of amplification and attenuation on signal-to-noise ratio are obtained for both direct and homodyne detection. Particular attention is paid to the extents to which the non-classical properties of photon antibunching and squeezing are preserved by amplification and attenuation. It is found that both properties can at best survive only twofold intensity amplification.
edGNN: a Simple and Powerful GNN for Directed Labeled Graphs

The ability of a graph neural network (GNN) to leverage both the graph topology and graph labels is fundamental to building discriminative node and graph embeddings. Building on previous work, we theoretically show that edGNN, our model for directed labeled graphs, is as powerful as the Weisfeiler-Lehman algorithm for graph isomorphism. Our experiments support our theoretical findings, confirming that graph neural networks can be used effectively for inference problems on directed graphs with both node and edge labels. Code available at this https URL.
A simplified model of the formation of a deep potential well in a vacuum diode

The nonstationary problem of the formation of a virtual cathode in a diode with an accelerating electric field and a high-current electron beam entering the diode has been solved numerically. As a result, the possibility of the formation of a deep nonstationary well in the presence of an electric field in the diode gap has been shown and a model for the current passage and the formation of such a well in an explosive-electron-emission vacuum diode has been proposed.
ROSAT PSPC OBSERVATIONS OF NGC 4636 : INTERACTION WITH VIRGO GAS ?

ROSAT Position Sensitive Proportional Counter (PSPC) observations of NGC 4636 have provided a deep image of the galaxy and its surroundings, which reveal the presence of emission well outside the optical galaxy. The source emission is measured out to r approximately 18 min, where the instrument support structure prevents us at this time from following it farther out. The nature of this emission is not fully understood, but could be evidence that the Virgo cluster gas extends as far out as this galaxy (greater than 3 Mpc from M87). Spectral analysis of the X-ray emission suggests a relatively cool (kT approximately 0.5 to 0.9 keV) interstellar medium, with temperatures increasing with radius. However, the detailed properties of the interstellar gas cannot be unambiguously determined with the present data, since the results we obtain depend strongly on the choice of the spectral model. Comparison of the spectral distributions in concentric annuli clearly indicates significant differences with radius, which can be parameterized as a general increase of the temperature. For low cosmic abundance models, kT varies from approximately 0.55 keV in the inner 1 min to approximately 0.8 keV at r approximately 6 to 8 min. Outside 8 min the average temperature is higher than in the inner region (kT approximately 0.8 to 1.2 keV) and the low-energy absorption is significantly lower. For 100% cosmic abundance and galactic line-of-sight absorption, multi-temperature fits are required, suggesting the possibility that the interstellar medi um is inhomogeneous.
Force distribution in frictionless granular packings at rigidity threshold

With a new simulation method, involving viscous lubricating forces, we identify the exact list of active contacts in a model two-dimensional frictionless granular packing at equilibrium under an isotropic load. Within a well-justified approximation of infinitesimal displacements, efforts are localized on a minimal central-force structure that satisfies a geometric optimization criterion. Size and boundary effects are analysed. The maximum packing density of discs is evaluated to first order in their small polydispersity parameter. We find no diverging correlation length in the thermodynamic limit, and accurately compute the distribution of contact forces in large systems.
Attentive Single-Tasking of Multiple Tasks

In this work we address task interference in universal networks by considering that a network is trained on multiple tasks, but performs one task at a time, an approach we refer to as ``single-tasking multiple tasks''. The network thus modifies its behaviour through task-dependent feature adaptation, or task attention. This gives the network the ability to accentuate the features that are adapted to a task, while shunning irrelevant ones. We further reduce task interference by forcing the task gradients to be statistically indistinguishable through adversarial training, ensuring that the common backbone architecture serving all tasks is not dominated by any of the task-specific gradients. Results in three multi-task dense labelling problems consistently show: (i) a large reduction in the number of parameters while preserving, or even improving performance and (ii) a smooth trade-off between computation and multi-task accuracy. We provide our system's code and pre-trained models at http://https://github.com/facebookresearch/astmt.
The Saturation of Gravity Waves in the Middle Atmosphere. Part II: Development Of Doppler-Spread Theory

Abstract The irregular winds of the middle atmosphere are commonly attributed to an upwardly propagating system of atmospheric gravity waves. Their one-dimensional (in vertical wavenumber m) power spectrum has been reported to exhibit a nearly universal behavior in its “tail” region of large m: both the form (∼m−3) and the intensity of the tail are approximately invariant with meteorological conditions, time, place and height. This universality is often described as resulting from “saturation” of the system, with the physical cause of saturation being left for separate identification and analysis. Here the cause is attributed to nonlinear interaction between the waves of the full spectrum, most specifically to the advective nonlinearity of the Eulerian fluid-dynamic equations. This nonlinearity has the effect of Doppler shifting the local intrinsic frequency of any given wave in the wind field imposed by all waves. Only an approximation to its effects is sought here, the wind field of the full spectrum be.
Oxygen adsorbed on oxidized Ru(0001)

An atomic oxygen species adsorbed on Ru(0001) containing subsurface oxygen has been found and is characterized by the means of thermal description spectroscopy (TDS), ultraviolet photoemission spectroscopy, and reactive CO scattering. The surplus oxygen can be adsorbed on an oxygen-rich ruthenium crystal at room temperature when more than two monolayers of oxygen are deposited in the subsurface region $(1 \mathrm{ML}=1.58\ifmmode\times\else\texttimes\fi{}{10}^{15} {\mathrm{cm}}^{\ensuremath{-}2}). $ The maximum number of oxygen atoms occupying this state depends on the oxygen content in the subsurface region. It saturates for oxygen contents higher than about 10 ML at a level of 0.25 ML. The initial binding energy of an adsorbed oxygen atom, as derived from TDS data, is lower than 0.75 eV per atom. It continuously decreases with increasing lateral adatom density. The work function $\ensuremath{\varphi}$ varies with the increasing population of this oxygen state. For saturating oxygen coverage it reaches a maximum that can be by 1.3 eV higher than the value known for a clean metallic Ru surface. The CO oxidation was performed in a beam scattering experiment and it reveals a high reactivity of this weakly bound state. At room temperature the $\mathrm{CO}/{\mathrm{CO}}_{2}$-conversion probability reaches a value of 0.18, which is nearly by one order of magnitude higher than the one found for subsurface oxygen at much higher temperatures.
A Variable-Velocity, Precessing Jet Model for HH 32

HH 32 has a bright, strongly redshifted lobe with a system of scattered condensations. We propose that these condensations correspond to internal working surfaces in a variable ejection velocity, precessing jet. From a three-dimensional numerical simulation, we obtain predictions of [O II] λ3726+λ3729, [O III] λ5007, [O I] λ6300, Hα, [N II] λ6583, and [S II] λ6716+λ6731 intensity maps, for an orientation angle of ∼70° between the outflow axis and the plane of the sky (as appropriate for HH 32). We also obtain predictions of radial velocity channel maps. We then compare these predictions with previously published observations of HH 32 and discuss the strengths and weaknesses of the model.
Flexible modelling of the covariance matrix in a linear random effects model

A flexible approach is proposed for modelling the covariance matrix of a linear mixed model for longitudinal data. The method combines parametric modelling of the random effects part with flexible modelling of the serial correlation component. The approach is exemplified on weight gain data and on the evolution of height of children in their first year of life of the Jimma Infant Survival Study, an Ethiopian cohort study. The analyses show the usefulness of the approach.
Globular cluster system of the galaxy. I. The metal abundances and reddenings of 79 globular clusters from integrated light measurements

Photoelectric photometry of the integrand light of globular clusters in selected filter passbands has been used to derive estimates of their interstellar reddenings and metal abundances (i.e., (Fe/H)). The uncertainties in these estimates average +- 0.03 in E (B--V) and +- 0.10 in (Fe/H), which are not much larger than the uncertainties in the estimates derived from the best methods that rely on observations of individual stars in the clusters. Seventy-nine globular clusters have been observed with our technique, which brings to 84 the total number of globular clusters with precise estimates of metal abundance.
High-pressure phases of germanium

We report a first-principles study of high-pressure phases of Ge finding that a Cmca phase is stable in the pressure range 91-155 GPa, while at higher pressures the hcp phase has lower enthalpy. The structural parameters of the Cmca phase are similar to those of other Cmca phases found in Si (Si-VI) and Cs (Cs-V). Our results challenge the experimental report of a transition from the simple hexagonal phase to a double hexagonal close-packed phase in this material.
A Dispersive Homogenization Model Based on Lattice Approximation for the Prediction of Wave Motion in Laminates

The propagation of elastic waves in a periodic laminate is considered. The stratified medium is modeled as a homogenized material where the stress depends on the strain and additional higher order strain gradient terms. The homogenization scheme is based on a lattice model approximation tuned on the dispersive properties of the real laminate. The long-wave asymptotic approximation of the model shows that, despite the simplicity of the parameters identification, the proposed approach agrees well with the exact solution in a wide range of elastic impedance contrasts, also in comparison with different approximations. The effect of increasing order of approximation is also investigated. A final example of a finite structure under an impact excitation proves that the model behaves well when applied in the transient regime and that it can be considered a simple but consistent approach to build efficient algorithms for the numerical analysis of elastodynamics problems. [DOI: 10.1115/1.4005579]
The Riemann hypothesis and the Turán inequalities

A solution is given to a fifty-eight year-old open problem of G Polya, involving the Taylor coefficients of the Riemann ? -function. 1. Introduction. The purpose of this paper is to solve a fifty-eight year-old problem of Polya (P, p. 16), related to the Riemann Hypothesis. This problem may be described as follows. Starting with Riemann's definition of his ? -function (cf. Titchmarsh (T, p. 16), in a slightly different notation), i.e.,
<formula formulatype="inline"><tex Notation="TeX">$K$</tex> </formula> Constrained Shortest Path Problem

Motivated by a real project for a sophisticated automated storage and retrieval system (AS/RS), we study the problem of generating K shortest paths that are required to satisfy a set of constraints. We propose a structural branching procedure that decomposes the problem into at most K|N| subproblems, where |N| is the number of nodes in the network. By using a Network Modification procedure, each subproblem can be transformed into a constrained shortest path problem (CSP). When these constraints satisfy a so called separable property, the subproblem can be further simplified. Based on this branching procedure, we propose a specific algorithm for an application where resource and loopless constraints have to be respected. Numerical results show that our algorithm is very efficient and robust.
Lattice models of branched polymers: statistics of uniform stars

The authors investigate the statistical properties of uniform star polymers with f branches, modelled on lattices in two and three dimensions. It is shown that the growth constant exists and is equal to mu f, where mu is the self-avoiding walk limit. The f dependence of the corresponding critical exponent gamma (f) is studied using exact enumeration and Monte Carlo techniques and the results are compared with the predictions of Miyake and Freed (1983) obtained using chain conformation space renormalisation group method.
Decomposition of bipartite states with applications to quantum no-broadcasting theorems

Correlations in bipartite quantum states are fundamental objects in quantum information theory. A canonical framework for studying correlations is the entangled versus separable dichotomy in which the decompositions of separable states as convex combinations of product states play an instrumental role. In this paper, motivated by both the representation of separable states and quantum no-broadcasting considerations, we establish a constructive decomposition representation for any bipartite state. As applications, we prove the conjectures proposed by Luo [Lett. Math. Phys. 92, 143 (2010)] concerning no-unilocal broadcasting for quantum correlations and further provide a unified picture for the celebrated quantum no-broadcasting theorem for noncommuting states by Barnum et al. [Phys. Rev. Lett. 76, 2818 (1996)], and the elegant no-local-broadcasting theorem for quantum correlations by Piani et al. [Phys. Rev. Lett. 100, 090502 (2008)]. The results reveal some intrinsic relation between quantumness of correlations and noncommutativity of states, and in particular, provide a characterization for zero quantum discord introduced by Ollivier and Zurek [Phys. Rev. Lett. 88, 017901 (2001)] from the broadcasting perspective. Furthermore, it is indicated that the distinction between the decomposition for general bipartite states and that for separable states might be useful in studying entanglement versus separability.
Altruism and Social Learning in Kuwait; an Analysis of Gender Differences

Our paper aims to identify the gender differences in helping behavior. It also seeks to explore how gender roles and prescribed norms affect the kind of helping behavior displayed by men and women in Kuwait, a collectivist society. In addition, we examine how altruism is related to the social learning theory and the effects of media as a major component of social learning. Authors explored whether altruistic behavior is impacted by observing others perform helping behavior. The Rushton et al. "Self-Report Altruism" scale was used to gather this information. We distributed 652 surveys to respondents between the ages of 18-33 living in Kuwait. The main findings concluded that males living in Kuwait are more altruistic than females and as both males and females get older, they tend to help more. Furthermore, the results show that there is a strong correlation between the social theory and altruistic behaviors. In Kuwait, both culture and religion emphasize that men are expected to provide help both at home and work, whereas women are only expected to provide help at home.
Interpolation of periodically correlated stochastic sequences

We study the problem of optimal estimation of a linear functional of unknown values of a periodically correlated random sequence from observed values of a sequence with an additive noise. Formulas for calculating the mean square error and spectral characteristic of the optimal linear estimate of a functional are established in the case where the spectral densities are known. The least favorable spectral densities and minimax spectral characteristic of the optimal linear estimate of a functional are found for some classes of admissible spectral densities.
Influence of individual factors on student science performance in primary education

The present paper aims to analyse the effects of individual factors on student science performance in primary education. This is an ex post facto study using the TIMSS 2019 database. The sample comprised 9512 Spanish students undertaking 4th grade primary education (51.6% boys; 48.4% girls) at 535 schools. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) of the 20 items comprising the student questionnaire on the science teaching and learning process (KMO =.93) were performed. Four factors were identified: student attitude, anxiety and self-efficacy towards the sciences and teacher attitude. Multiple regression analysis was used to predict the influence of student factors on science performance. Outcomes show that student attitudes determine their self-efficacy and that anxiety has a negative impact on performance. Teacher attitude is the most predictive factor regarding performance. The number of books at home which, in itself, is an indicator of socioeconomic status, has a substantial effect on performance. Findings suggest the need to enhance student motivation towards science during the first years of primary education, promote the application of knowledge to solve scientific problems and conduct experiments in Science classes
The helium shell game: nonradial g-mode instabilities in hydrogen-deficient planetary nebula nuclei

Preliminary results of fully nonadiabatic g-mode pulsation calculations for evolutionary models of hydrogen-deficient planetary nebula nuclei (PNNs) with active helium-burning shells are reported. Instabilities are found that are driven by the epsilon-mechanism at the position of the helium-burning shell. The periods of the unstable modes range from 50 to 214 s. In all models, the presence of an active nuclear burning shell demands that some g-modes are unstable. It is suggested that if hydrogen-deficient PNNs contain helium-burning shells, then they should show such pulsations. 23 references.
Arf-like Protein 2 (ARL2) Controls Microtubule Neogenesis during Early Postnatal Photoreceptor Development

Arf-like protein 2 (ARL2) is a ubiquitously expressed small GTPase with multiple functions. In a cell culture, ARL2 participates with tubulin cofactor D (TBCD) in the neogenesis of tubulin αβ-heterodimers, the building blocks of microtubules. To evaluate this function in the retina, we conditionally deleted ARL2 in mouse retina at two distinct stages, either during the embryonic development (retArl2−/−) or after ciliogenesis specifically in rods (rodArl2−/−). retArl2−/− retina sections displayed distorted nuclear layers and a disrupted microtubule cytoskeleton (MTC) as early as postnatal day 6 (P6). Rod and cone outer segments (OS) did not form. By contrast, the rod ARL2 knockouts were stable at postnatal day 35 and revealed normal ERG responses. Cytoplasmic dynein is reduced in retArl2−/− inner segments (IS), suggesting that dynein may be unstable in the absence of a normal MTC. We investigated the microtubular stability in the absence of either ARL2 (retARL2−/−) or DYNC1H1 (retDync1h1−/−), the dynein heavy chain, and found that both the retArl2−/− and retDync1h1−/− retinas exhibited reduced microtubules and nuclear layer distortion. The results suggest that ARL2 and dynein depend on each other to generate a functional MTC during the early photoreceptor development.