Miracle-dz/UniFAR-FTUs huggingface dataset:
VLA IMAGING OF VIRGO SPIRALS IN ATOMIC GAS (VIVA). I. THE ATLAS AND THE H i PROPERTIES

We present the results of a new VLA H i Imaging survey of Virgo galaxies, the VLA Imaging survey of Virgo galaxies in Atomic gas (VIVA). The survey includes high-resolution H i data of 53 carefully selected late type galaxies (48 spirals and five irregular systems). The goal is to study environmental effects on H i gas properties of cluster galaxies to understand which physical mechanisms affect galaxy evolution in different density regions, and to establish how far out the impact of the cluster reaches. As a dynamically young cluster, Virgo contains examples of galaxies experiencing a variety of environmental effects. Its nearness allows us to study each galaxy in great detail. We have selected Virgo galaxies with a range of star formation properties in low to high density regions (at projected distances from M87, d87 = 0.3–3.3 Mpc). Contrary to previous studies, more than half of the galaxies in the sample (∼60%) are fainter than 12 mag in BT. Overall, the selected galaxies represent the late type Virgo galaxies (S0/a to Sd/Irr) down to mp ≲ 14.6 fairly well in morphological type, systemic velocity, subcluster membership, H i mass, and deficiency. The H i observations were done in C short (CS) configuration of the VLA radio telescope, with a typical spatial resolution of 15″ and a column density sensitivity of ≈3–5 × 1019 cm−2 in 3σ per 10 km s−1 channel. The survey was supplemented with data of comparable quality from the NRAO archive, taken in CS or C configuration. In this paper, we present H i channel maps, total intensity maps, velocity fields, velocity dispersions, global/radial profiles, position–velocity diagrams and overlays of H i/1.4 GHz continuum maps on the optical images. We also present H i properties such as total flux (SH i), H i mass (MH i), linewidths (W20 and W50), velocity (VH i), deficiency (defH i), and size (DeffH i and DisoH i), and describe the H i morphology and kinematics of individual galaxies in detail. The survey has revealed details of H i features that were never seen before. In this paper, we briefly discuss differences in typical H i morphology for galaxies in regions of different galaxy densities. We confirm that galaxies near the cluster core (d87 ≲ 0.5 Mpc) have H i disks that are smaller compared to their stellar disks (DH i/D25 < 0.5). Most of these galaxies in the core also show gas displaced from the disk, which is either currently being stripped or falling back after a stripping event. At intermediate distances (d87 ∼ 1 Mpc) from the center, we find a remarkable number of galaxies with long one-sided H i tails pointing away from M87. In a previous letter, we argue that these galaxies are recent arrivals, falling into the Virgo core for the first time. In the outskirts, we find many gas-rich galaxies, with gas disks extending far beyond their optical disks. Interestingly, we also find some galaxies with H i disks that are smaller compared to their stellar disks at large clustercentric distances.
A second-order description of shock structure

The structure of gas-dynamic shock waves is of interest in hypersonic flow studies and also constitutes a straightforward test for competing kinetic theories. The description of the shock profiles may be obtained from a second-order theory in the Knudsen number. The BGK approximation to the Boltzmann equation introduces additional terms in the transport of momentum and energy. These relations, known as the Burnett equations, improve the agreement between calculated shock profiles and experiment. However, for some formulations of these equations, the solution breaks down at a critical Math number. In addition, certain terms in the Burnett equations allow unphysical effects in gas flow. A modified kinetic theory has been proposed by Woods (An Introduction to the Kinetic Theory of Gases and Magnetoplasmas, Oxford Univ. Press, Oxford, 1993) which eliminates the frame dependence of the standard kinetic theory and corrects some of the second-order terms. This article describes a novel method devised to solve the time-independent conservation equations, including the second-order terms. The method is used to solve the shock structure problem in one dimension. It is based on a finite difference global scheme (FDGS), in which a Newton procedure is applied to a discretized version of the governing equations and boundary conditions. The method is first applied to the Navier-Stokes formulation of the shock equations. It is then successfully used to integrate a modified version of the second-order equations derired by Woods for monatomic gases, up to a Mach number of 30. Results of the calculations are compared with experimental data for Argon gas flows characterized by up-stream Mach numbers up to 10. The agreement is good, well within the data point spread. The FDGS method converges rapidly and it may be used to study other problems of the same general nature.
New plasma diagnosis tables of hydrogen Stark broadening including ion dynamics

A set of tables of the Stark width of the first three lines of Lyman and Balmer series of hydrogen, useful for plasma diagnosis purposes, is presented in this work. These tables have been obtained by means of a fully recognized computer simulation technique. Computer experiments have been carried out for density values between and . Simulation temperatures range from 2245 K to 224 856 K. Ion dynamics effects are taken into account in a natural way and the most significative gas mixtures have been covered in the simulations, carried out at the reduced mass of the emitter - perturber pair , 0.6, 0.8, 0.9, 1.0, 1.25, 1.5, 1.75 and 2.0. A detailed discussion of the influence of the relevant plasma parameters on the characteristics of the profiles is also included. The results show an excellent agreement with up-to-date experimental results and confirm these kind of profile calculation techniques as now the most accurate.
Heavy-traffic analysis of a data-handling system with many sources

A model is considered in which a buffer receives messages from N independent and identical information sources that asynchronously alternate between exponentially distributed periods in the “on” and “off” states. While on, a source transmits at unit rate. The buffer depletes through an output channel with a given maximum transmission rate $c < N$. This model is useful for a data-handling switch in a computer network. Anick, Mitra, and Sondhi [Bell System Tech. J., 61 (1982), pp. 1871–1894] have derived an explicit expression for the equilibrium probability $G( x )$ that the buffer content exceeds x, which is convenient for numerical calculations for moderate values of N. In this paper, the heavy traffic case, in which N is large and the system is close to instability, is investigated. Important scalings are introduced, and a two-term asymptotic approximation to $G( x )$ is derived, with the help of function theoretic techniques. Numerical comparisons are given that show the quality of the approximation.
CALCULATION OF FLUID FLOWS WITH STAGGERED AND NONSTAGGERED CURVILINEAR NONORTHOGONAL GRIDS-A COMPARISON

This article compares two finite-volume methods for calculating flows inside complex geometries by curvilinear nonorthogonal coordinates. One method is based on a staggered grid arrangement together with physical covariani velocity projections as dependent variables in the momentum equations, and the other method is based on a nonstaggered grid arrangement together with Cartesian velocity components. Both methods use the SIMPLE algorithm. The comparison indicates that the two methods produce results with similar accuracy after about the same number of iterations. The nonstaggered method seems to manage highly distorted grids better than the staggered method, while the staggered method reaches a grid-independent solution earliest for flow with high pressure gradients. However, due to the simpler nonstaggered grid arrangement, reduced computer program system and reduced memory and calculation time, this method is recommended when using curvilinear nonorthogonal coordinates.
Scaling of viscoelastic shell properties of lipid encapsulated microbubbles with frequency.

While it has been established that nonlinear oscillations of lipid encapsulated microbubbles occur at frequencies of >10 MHz, the understanding of bubble behavior in this frequency range is limited and is not predicted by bubble models using shell properties derived at <5 MHz. Here we investigate the scaling of the viscoelastic shell properties of lipid encapsulated contrast agents with frequency and bubble size. Attenuation measurements were performed over 2–30 MHz and, using size distribution measurements and the linearized Rayleigh–Plesset equation, shell elasticity and viscosity terms were estimated. Experiments were performed on a series of narrow size distribution in‐house agents with progressively smaller diameters, as well as the high frequency agent Micromarker. In‐house agents peaked in attenuation at 4.2, 8.5, 13, and 22 MHz, and Micromarker rose until 21 MHz. The elasticity for in‐house agents was comparable to other agents at lower frequencies, while the viscosity rapidly decreased above 10 M.
A Shape-based Glaucoma Index for Tomographic Images

We examine the use of Confocal Laser Tomographic images for detecting glaucoma. From the clinical aspect, the optic nerve head's (ONH) area contains all the relevant information on glaucoma. The shape of ONH is approximately a skewed cup. We summarize its shape by three biological landmarks on the neural-rim and the fourth landmark as the point of the maximum depth, which is approximately the point where the optic nerve enters this eye cup. These four landmarks are extracted from the images related to some Rhesus monkeys before and after inducing glaucoma. Previous analysis on Bookstein shape coordinates of these four landmarks revealed only marginally significant findings. From clinical experience, it is believed that the ratio depth to diameter of the eye cup provides a useful measure of the shape change. We consider the bootstrap distribution of this normalized 'depth' (G) and give evidence that it provides an appropriate measure of the shape change. This measure G is labelled as the glaucoma index. Further experiments are in progress to validate its use for glaucoma in humans.
Three-dimensional microwave tomography. Theory and computer experiments in scalar approximation

The results of computer simulated experiments in three-dimensional microwave tomography in scalar approximation are presented. The gradient method is employed to solve three-dimensional high-contrast microwave tomographic problems. A computer model for full-scale three-dimensional imaging has been created. Three-dimensional tomographic images of mathematical models of the human torso were obtained. Significant differences between two-dimensional and three-dimensional cases are emphasized. Some illumination schemes which can be applied in the three-dimensional case are discussed. A dependence of image quality on the number of vertically placed transmitters has been demonstrated. The computer simulation showed that three-dimensional full-scale human torso dielectrical properties images can be produced with acceptable computational time.
Numerical methods for kinetic equations*

In this survey we consider the development and mathematical analysis of numerical methods for kinetic partial differential equations. Kinetic equations represent a way of describing the time evolution of a system consisting of a large number of particles. Due to the high number of dimensions and their intrinsic physical properties, the construction of numerical methods represents a challenge and requires a careful balance between accuracy and computational complexity. Here we review the basic numerical techniques for dealing with such equations, including the case of semi-Lagrangian methods, discrete-velocity models and spectral methods. In addition we give an overview of the current state of the art of numerical methods for kinetic equations. This covers the derivation of fast algorithms, the notion of asymptotic-preserving methods and the construction of hybrid schemes.
Development of a Global Infrared Land Surface Emissivity Database for Application to Clear Sky Sounding Retrievals from Multispectral Satellite Radiance Measurements

Abstract A global database of infrared (IR) land surface emissivity is introduced to support more accurate retrievals of atmospheric properties such as temperature and moisture profiles from multispectral satellite radiance measurements. Emissivity is derived using input from the Moderate Resolution Imaging Spectroradiometer (MODIS) operational land surface emissivity product (MOD11). The baseline fit method, based on a conceptual model developed from laboratory measurements of surface emissivity, is applied to fill in the spectral gaps between the six emissivity wavelengths available in MOD11. The six available MOD11 wavelengths span only three spectral regions (3.8–4, 8.6, and 11–12 μm), while the retrievals of atmospheric temperature and moisture from satellite IR sounder radiances require surface emissivity at higher spectral resolution. Emissivity in the database presented here is available globally at 10 wavelengths (3.6, 4.3, 5.0, 5.8, 7.6, 8.3, 9.3, 10.8, 12.1, and 14.3 μm) with 0.05° spatial reso.
Physical Conditions in Quiescent Dark Cloud Cores Determined from Multitransition Observations of CCS

We have studied three transitions of the CCS molecule to determine physical conditions in L1498 and TMC-1D, two narrow-line dense cores in the Taurus region. We observed the NJ = 12 → 01, 34 → 23, and 78 → 67 transitions at 22.3, 45.4, and 93.9 GHz, respectively, at 50'' angular resolution. The intensities of the emission lines have been analyzed using statistical equilibrium calculations and collision rates calculated for the CCS-H2 system. These were obtained from the Molscat scattering code together with inclusion of spin dependence in Hund's case (b) model. We find that the kinetic temperature in both sources is extremely low, between 7 and 10 K. The L1498 emission appears to originate in a single velocity component with mean hydrogen density 3-14 × 104 cm-3. We analyzed three velocity components in TMC-1D separately, and find that the low-velocity component has a mean H2 density of 6 × 103 cm-3, while the two higher velocity components are denser by approximately a factor of 3. The L1498 core is close to virial equilibrium in that the magnitude of its gravitational energy is close to that of its kinetic energy. However, the cores corresponding to the three velocity components in TMC-1D are unbound by factors of 2-7. We dedicate this paper to the memory of Sheldon Green, who passed away in 1995 December. Sheldon was an outstanding chemist who made many significant contributions to molecular astrophysics.
The Generalized Patch Test

The paper establishes the basic convergence conditions for the method of nonconforming finite elements applied to a class of generalized elliptic boundary value problems with variable, not necessarily smooth coefficients. The main result is a new, generalized patch test. Approximability and success in this test is the necessary and sufficient condition for convergence of the nonconforming approximations. It is proved that nonconforming elements of Wilson, Adini, Crouzeit–Raviart, Morley, and de Veubeke pass the generalized patch test and thus yield convergent approximations of the boundary value problems.
Are luminous and metal-rich Wolf-Rayet stars inflated?

Aims. We investigate the influence of metallicity and stellar wind mass loss on the radius of Wolf-Rayet stars. Methods. We have calculated chemically homogeneous models of Wolf-Rayet stars of 10 to 200 M for two metallicities (Z = 0.02 and Z = 0.001), without mass loss, using OPAL opacities. We also constructed theoretical helium main sequences for 15, 18, 24 and 30 M with stellar wind mass loss rates of 10−5 M yr−1 and 10−4 M yr−1 and models for a 24 M star for a few intermediate values of mass loss rate. Results. We confirm the radius extension for luminous, metal-rich Wolf-Rayet stars reported previously by Ishii et al. (1999, PASJ, 51, 417), i.e. the inflation of the hydrostatic stellar radius. We also show that for small values of the stellar wind mass loss rate, an extended envelope structure is still present. However, for mass loss rates above a critical value, for which we derive an expression, Wolf-Rayet radii decrease and the stellar structure becomes compact. We briefly discuss possible evolutionary and observational consequences of an inflated envelope for a mass losing Wolf-Rayet star.
Calculation and Evaluation of an Air-Freezing Index for the 1981–2010 Climate Normals Period in the Coterminous United States

AbstractThe air-freezing index (AFI) is a common metric for determining the freezing severity of the winter season and estimating frost depth for midlatitude regions, which is useful for determining the depth of shallow foundation construction. AFI values represent the seasonal magnitude and duration of below-freezing air temperature. Departures of the daily mean temperature above or below 0°C (32°F) are accumulated over each August–July cold season; the seasonal AFI value is defined as the difference between the highest and lowest extrema points. Return periods are computed using generalized extreme value distribution analysis. This research replaces the methodology used by the National Oceanic and Atmospheric Administration to calculate AFI return periods for the 1951–80 time period, applying the new methodology to the 1981–2010 climate normals period. Seasonal AFI values and return period values were calculated for 5600 stations across the coterminous United States (CONUS), and the results were validat.
Thermal Resistivity Changes in Electron-Irradiated Pyrolytic Graphite

Changes in the a-axis and the c-axis thermal resistivity of pyrolytic graphite caused by electron irradiation at 82 K and by subsequent isochronal pulse annealing have been measured. The additive thermal resistivity at 78.5 K increases as 9.6×102N0.85f and (7.9±0.6)×103N0.75f cm deg/W in the a-axis and the c-axis directions, respectively, in the region of 2 ppm<Nf<70 ppm, where Nf is the concentration of nearly isolated Frenkel defects produced by irradiation. Annealing of the additive thermal resistivity occurs around 100 K and above about 220 K. The characteristics of annealing stages are different in some important respects from those obtained by Goggin and Reynolds. It is inferred that most interstitials do not recombine with vacancies below about 220 K.
Outflow Interaction in the Late Stages of Star Formation

We have mapped the CO, HCO+, N2H+, and CS emission around a nearby T Tauri star, IRAS 16316-1540. A molecular outflow is seen in CO, HCO+, N2H+, and CS emission originating from the IRAS source, while an envelope is seen in N2H+ and HCO+ emission surrounding the IRAS source. The molecular outflow is bipolar with a southeastern (SE) lobe and a northwestern (NW) lobe. The structure and the kinematics of the SE lobe are well defined and can be explained with a simple kinematic model. In this model, the SE lobe is a U-shaped shell consisting of a wide-opening base mimicking the reflection nebula RNO 91 and a cylindrical shell with a constant radius mimicking the CO outflow shell. The wide-opening base is expanding toward the circumstellar envelope, while the cylindrical shell is expanding mainly laterally into the ambient medium. If the base of the SE lobe continues to expand at its current velocity, it will meet with the base of the NW lobe and disperse the circumstellar envelope in a few times 104 yr. The circumstellar envelope is elongated perpendicular to the outflow axis, extending to the northeast and southwest of the IRAS source. The envelope has differential rotation with the velocity increasing toward the source. It may result from material infalling toward the source carrying its angular momentum. The HCO+ emission near the source may arise from an unresolved inner ring of the envelope, showing two peaks with one on each side of the IRAS source and a position-velocity structure consistent with the rotation law derived from the N2H+ emission. The HCO+ emission in the outer part of the envelope likely traces the swept up envelope material, showing both the outflow motion and probably rotation.
Particle acceleration and coronal mass ejection driven shocks: A theoretical model

There is increasing evidence to suggest that energetic particles observed in “gradual” solar energetic particle (SEP) events are accelerated at shock waves driven out of the corona by coronal mass ejections. Energetic particle abundances suggest too that SEPs are accelerated from in situ solar wind or coronal plasma rather than from high‐temperature flare material. A dynamical time‐dependent model of particle acceleration at a propagating, evolving interplanetary shock is presented here. The theoretical model includes the determination of the particle injection energy (injection here refers to the injection of particles into the diffusive shock acceleration mechanism), the maximum energy of particles accelerated at the shock, energetic particle spectra at all spatial and temporal locations, and the dynamical distribution of particles that escape upstream and downstream from the evolving shock complex. As the shock evolves, energetic particles are trapped downstream of the shock and diffuse slowly away. In the immediate vicinity of the shock, broken power law spectra are predicted for the energetic particle distribution function. The escaping distribution consists primarily of very energetic particles initially with a very hard power law spectrum (harder than that at the shock itself) with a rollover at lower energies. As the shock propagates further into the solar wind, the escaping ion distribution fills in at lower energies, and the overall spectrum remains hard. Downstream of the shock, the shape of the accelerated particle spectrum evolves from a convex, broken power law shape near the shock to a concave spectrum far downstream of the shock. Intensity profiles for particles of different energies are computed, and the relation between arrival times, maximum predicted energies, and shock propagation characteristics are described. These results are of particular importance in the context of predictive space weather studies.
Benchmark simulations for electron swarms in crossed electric and magnetic fields

Monte Carlo methods have been used to produce accurate benchmark transport parameters for electron swarm transport in four model gases in the presence of crossed electric and magnetic fields, for a wide range of applied electric and magnetic field strengths. The results of the simulations are compared with those predicted by a multi-term (moment method) solution of Boltzmann's equation and by the flight-time integral method (FTI) of Ikuta and Sugai when possible. The comparison clearly validates the theoretical basis and numerical integrity of the moment method, while supporting concerns about the validity of the FTI approach and the definition of the transport coefficients used. Certain trends in the transport coefficients in crossed electric and magnetic fields are addressed using physical arguments.
Spatial Instability in Dislocation Structure under Irradiation

In many materials, the dislocation structure after irradiation is observed to be heterogeneous, with regions of high dislocation density separated by ones of low dislocation density. Using a simple rate theory model with one-dimensional diffusion of point defects (vacancies and interstitials), we show that spatial instabilities can arise for a general class of models for dislocation evolution. The numerical results obtained for density oscillations and their wave-lengths reproduce qualitatively both the magnitudes and trends with temperature of observed heterogeneous structures.