Miracle-dz/UniFAR-FTUs huggingface dataset:
Three-Dimensional Modeling of Compressible Magnetohydrodynamic Turbulence in the Local Interstellar Medium

We apply the large eddy simulation technique to carry out a three-dimensional numerical simulation of compressible magnetohydrodynamic turbulence in conditions relevant to the local interstellar medium. In accord with the large eddy simulation method, the large-scale part of the flow is computed directly and only small-scale structures of turbulence are modeled. The small-scale motion is eliminated from the initial system of equations of motion by filtering procedures, and its effect is taken into account by special closures referred to as the subgrid-scale models. Establishment of the weakly compressible limit with a Kolmogorov-like density fluctuation spectrum is shown in the present work. We use our computation results to study the dynamics of the turbulent plasma beta and anisotropic properties of the magnetoplasma fluctuations in the local interstellar medium.
The Effect of Accommodation on Heat Conduction through Gases

An experimental determination of the thermal conductivity of a gas necessarily involves a number of corrections which must either be determined or eliminated before an absolute value can be obtained. With the " hot-wire " method the inherent errors are: (1) the beat lost by radiation ; (2) the beat losses due to convection; (3) the temperature discontinuity between the gas and solid surfaces ; and (4) the fact that the interchange of energy between the gas molecules and the solid surfaces is not perfect. The true temperature attained by a molecule striking a bot surface always being less than the temperature of that surface. previous investigators using this method have applied a correction for the beat lost by radiation, determined by measuring the beat loss in the best obtainable vacuum ; while the convective beat loss has been eliminated, either by simply reducing the pressure or by using a double system of tubes. Both methods are debatable, for the first is very inaccurate, while the second necessarily complicates the experimental arrangement.
Direct detection of the Josephson radiation emitted from superconducting thin-film microbridges

We report direct measurements of the Josephson radiation emitted in X band from a superconducting thin‐film microbridge coupled to a resonance cavity. Power is emitted if one of the harmonics of the Josephson frequency is in the bandwidth of the receiver. The maximum power emitted during our experiment was 10−13 W. The Josephson radiation could easily be detected at frequencies off resonance.
Air-Sea Interaction Effects in the Lower Troposphere Across the North Wall of the Gulf Stream

Abstract Significant atmospheric and oceanographic differences have often been observed in the regions lying on either side of the north wall of the Gulf Stream. Satellite visible-range sensors have revealed changes in reflectivity across the Gulf Stream believed to be due to changes in sea state that are related to these atmospheric and oceanic differences. In addition, lines of low-level cloud, paralleling the edge of the Gulf Stream, have been observed to persist in satellite imagery for several days at a time. Anomalous radar propagation also has been noted to occur in these same regions. In an attempt to document the interrelation of these phenomena, the lower atmosphere over the north wall of the Gulf Stream was studied on two separate occasions. Sea state photography and measurements of sea surface temperature, air temperature, dew-point temperature and atmospheric pressure were made by an instrumented RP-3A aircraft flying at various altitudes from the Gulf Stream, across the north wall, and onto .
Size-dependent modulation of carrier mobility in top-down fabricated silicon nanowires

We have investigated the size dependence of field-effect mobility in top-down fabricated Si nanowires (NWs). We find that electron mobility increases while hole mobility decreases with the NW width. The observed trends are opposite of what we expect based on facet-dominated transport. We simulate charge densities and investigate the effect of gate stack-induced stress in an effort to explain these trends. We find that the use of piezoresistive coefficients for bulk or thin-film Si does not give sufficient change in mobility to reverse the facet-driven mobility trend. We suggest further investigation into the contribution of one-dimensional NW corner effects.
An exponential inequality under weak dependence

Mixing conditions are the classical concept for imposing a restriction on the dependence between time series data. However, many classes of processes which are of interest in statistics do not satisfy any such conditions. Examples include processes driven by discrete innovations as they appear with model-based time series bootstrap methods. Doukhan and Louhichi (1999) proposed a new condition of weak dependence which uses covariances rather than the total variation norm as in the case of mixing. It has been shown that this concept is more general than mixing and includes, under natural conditions on the parameters, essentially all classes of processes of interest in statistics. Ango Nze et al. (2002) provide many examples, including Markov processes and so-called Bernoulli shifts. The case of ARCH(p) processes is discussed in Neumann and Paparoditis (2004). It became readily apparent that the concept of weak dependence allows in many instances the same tools to be used as in the independent or mixing case. For example, versions of a central limit theorem are derived in Doukhan and Louhichi (1999) for sequences of random variables, in Coulon-Prieur and Doukhan (2000) for situations as they appear with nonparametric curve estimators, and in Neumann and Paparoditis (2004) for triangular schemes. A first exponential inequality was obtained in Doukhan and Louhichi (1999) and a Bennett inequality was proved in Dedecker and Prieur (2004). The major contribution of this paper is a new Bernstein-type inequality for weakly dependent random variables. Our conditions are slightly stronger than those in Dedecker and Prieur (2004); in particular, we assume an exponential decay of the coefficients of weak dependence. For typical time series models, one often has such an exponential decay under conditions on the parameters which are almost necessary for ergodicity. On the other hand, in contrast to a Bernstein-type inequality which follows from the Bennett inequality of
Axial structure of a plasma column produced by a large‐amplitude electromagnetic surface wave

Electromagnetic surface waves in the rf and microwave frequency range can be used to produce long large/small‐diameter plasma columns. We propose a theory of surface‐wave‐produced plasmas at two different low‐pressure gas‐discharge regimes, diffusion and recombination, respectively. For a given regime the axial plasma density profile is specified by two quantities: a numerical parameter σ=ωR/c (ω being the wave frequency, R the tube radius, and c denoting the speed of light) and the collision frequency ν (ν≪ω). Our theory predicts the magnitude of the axial electron number density gradient. The very good agreement between the experimentally measured plasma density gradients and the theoretically calculated ones for diffusion‐controlled surface‐wave‐produced plasma columns confirms the adequacy of the proposed model.
Spectroscopic study of a laser-produced lead plasma: experimental atomic transition probabilities for Pb III lines

The optical emission from a laser produced plasma (LPP) generated by a 10 640 Å laser irradiation, with a flux of 2 × 1010 W cm-2, on Pb targets was recorded and analysed between 2000 and 7000 Å; spectral lines emitted by the first two ionization species of Pb were studied in a wide range of plasma parameters. First experimental values of the atomic transition probabilities for ten spectral lines of Pb III have been determined by measurement of emission line intensities from an optically thin LPP of Pb in an atmosphere of Ar. The studied plasma has a temperature of about 25 300 K and an electron density of 1017 cm-3. Local thermodynamic equilibrium conditions and plasma homogeneity has been checked.
THE USE OF TRANSPORT APPROXIMATION AND DIFFUSION-BASED MODELS IN RADIATIVE TRANSFER CALCULATIONS

The paper presents a discussion of the use of both transport approximation for scattering phase function and diffusionbased models for radiative transfer in absorbing and anisotropically scattering media like many disperse systems in nature and engineering. The main attention is paid to heat transfer problems and traditional methods of identification of spectral radiative properties of dispersed materials when the details of angular distribution of the radiation intensity are not so important. The latter makes reasonable use of the above-mentioned approximations. In more complex applied problems, the diffusion approximation appears to be a good approach as the first step of a combined two-step solution. Some example problems solved recently by the author and his colleagues are used to illustrate the approach considered in the paper.
The science of brown dwarfs

This review summarizes the current status of both brown dwarf theory and the searches for these elusive substellar objects. The conceptual continuity between the brown dwarf and the well-studied M dwarf branches is emphasized throughout. The physics of their atmospheres and interiors is reviewed and an analytic model of both brown dwarf evolution and the lower edge of the hydrogen main sequence is presented. An extensive discussion of brown dwarf searches in the field, in binaries, around white dwarfs, in clusters, in the solar neighborhood, in the galactic halo, and using proper-motion catalogs is provided, as is a tentative list of candidates in the field. The theory near and below the edge of the main sequence, while sophisticated, is only now being successfully challenged by optical and infrared observations. The near future promises a productive explosion in our knowledge of this problematic galactic population.
Chemical separation in horizontal-branch stars.

Abundance anomalies are predicted to be produced by diffusion processes in horizontal-branch (HB) and halo Population II stars. If the outer envelope is stable enough for the gravitational settling of He to be efficient, it is here shown that overabundances of heavy elements are simultaneously produced. Abundance anomalies as large as 10/sup 3/--10/sup 4/ are expected. Detailed calculations of selective radiative accelerations and of the time evolution of abundances are presented for C, N, O, Ca, Fe, and Sr in a series of models representative of HB stars. These abundance anomalies may be important for what is called the ''second parameter problem'' in globular clusters. By detailed time dependent calculations, helium underabundances and relative overabundances of /sup 3/He are shown to be produced well within the lifetime of stars on the horizontal branch. The implications of helium underabundances on the pulsational properties of RR Lyrae variables are discussed. The role of turbulent mixing in reducing the abundance anomalies is discussed. It is shown that even with enough turbulence to prevent He from settling, heavy element abundance anomalies are possible. Even though chemical separation is very likely to be important in the blue horizontal-branch stars (T>15,000 K), it may not bemore » in the cooler stars where mass loss could eliminate any effect of chemical separation. This could be verified by observations of horizontal-branch stars in globular clusters. « less
Cirrus Cloud Simulation Using Explicit Microphysics and Radiation. Part I: Model Description

Abstract A mesoscale 2D/3D cloud model complex with explicit account for the water and ice cloud microphysics and radiative processes is described. The model has several versions suitable for the simulation of various cloud types, including, of particular concern in the current version, cirrus clouds. Model computations are based on the two kinetic equations for droplet and crystal size distribution functions, with division of droplet and crystal size spectra into 30 bins from 1 μm to 3.5 mm, and with account for the various mechanisms of cloud condensation and ice nuclei activation, condensation–deposition, and coalescence–accretion growth. These equations are solved along with supersaturation and radiative transfer equations for longwave and solar radiation. Simple yet accurate analytical expressions are presented for the scattering and absorption coefficients, and the single-scattering albedo. This allows detailed calculations of the optical and radiative characteristics of clouds (i.e., fluxes, diverg.
A laboratory study of the ice nucleating properties of some mineral particulates

Laboratory studies using a microscope cold stage with controlled humidity environment have been carried out on the ice nucleation and preactivation properties of several naturally occurring particulate substances. For initial nucleation water saturation was necessary, but below a critical temperature a constant ice supersaturation (water subsaturation), was sufficient. The values of both temperature and supersaturation depended on the substance. In preactivation the behaviour was similar but with a higher initial and critical temperature. Typical values are : for kaolinite, initial nucleation − 10·5, − 19°C, 20 per cent; preactivation − 6, − 11·5°C, 12 per cent: montmorillonite, − 25, below − 27°C; preactivation − 4, − 13·5°C, 14 per cent. The first temperature gives one ice crystal in 104 particles; the second is critical for nucleation at water subsaturation. The low values of supersaturation required for nucleation suggest that preactivation is caused by the freezing of a supercooled, adsorbed, liquid-like layer, rather than by the retention of ice embryos in cavities. A necessary condition for the measurement of the ice nucleating ability of particles from an air sample is that they must not be heated to a temperature above at least − 5°C or subjected to a relative humidity over ice of less than about 35 per cent before the measurement is made.
On bubbles rising in line at large Reynolds numbers

Conditions for two gas bubbles in a liquid to rise steadily in a vertical line are derived theoretically with these assumptions: large Reynolds number, no surface contamination, spherical shape, negligible gas density and viscosity. Drag coefficients are found, and are lower than for single bubbles. The bubbles have equilibrium distances apart, which are calculated to a first approximation. The equilibrium is shown to be stable to small vertical disturbances but unstable to horizontal ones. Similar results exist for lines of more than two bubbles, but are not calculated in detail.
A similarity coefficient measure and machine-parts grouping in cellular manufacturing systems

For more than three decades, similarity coefficient measures one of the important tools for solving group technology problems have gained the attention of the research community in cellular manufacturing systems. A new similarity coefficient measure that uses a set of important characteristic properties for grouping is developed here for use as an intermediate tool to form cohesive cells. A mathematical model that uses this similarity coefficient for optimally solving the cell-formation problems in cellular manufacturing is developed. A heuristic procedure that improves the optimal methodology in term of solution capability of the large instances is devised for an efficient solution. Both the optimal methodology and the heuristic are applied to some well-known problems from literature to compare the grouping efficiencies. The similarity coefficient and the solution methodologies developed are able to solve the cell formation problems efficiently.
UBVI CCD photometry of M35 (NGC 2168)

UBVI CCD photometry has been obtained for the intermediate-age open cluster M35 (NGC 2168). From this new photometry we derived the cluster parameters (V0−MV= 9.60 ± 0.10 mag, E(B−V) = 0.255 ± 0.024 mag), age (log tage=8.3 ±0.3) and a photometric abundance (Z≈ 0.008, i.e. [Fe/H] ≈− 0.3) from comparison with theoretical isochrones of the Padova group. A minimum binary frequency (35 ± 5 per cent) was estimated from the distribution of distance moduli of unevolved proper motion members. Faint photometric members were selected by using differences in the reddening effect on colour indices.
Hubble Space Telescope STIS Far-Ultraviolet Observations of the Central Nebulae in the Cooling-Core Clusters A1795 and A2597

We present Hubble Space Telescope STIS FUV images of the Lyα and FUV continuum emission of the luminous emission-line nebulae in two cooling-core clusters, A1795 and A2597. The Lyα and FUV continuum emission consist of a diffuse component (~60%) and more compact features (knots and filaments), which lie preferentially along the radio source edges. There are correlations between the FUV continuum flux and the emission-line fluxes of Lyα and Hα that imply that the brighter parts of the nebulae are ionized locally. We suggest that the FUV knots are star clusters with ongoing star formation of several solar masses per year. The bolometric luminosity of such a starburst (if absorbed by dust) would be detectable with the Spitzer Space Telescope MIPS. It appears that star formation occurs throughout the nebula, although it is strongly enhanced along the edges of the radio source. We find that young hot stars (e.g., O5) probably provide the bulk of the photons that ionize the nebula, although other sources of ionization may contribute in selected regions of the nebula. Constraints on diagnostic UV emission lines are consistent with photoionization from a starburst population and perhaps marginally with intermediate-velocity shocks, ~400 km s-1. We suggest that the mass accretion rates are comparable to the star formation rates (of order 10 M☉ yr-1). This is consistent with the lack of intermediate-temperature gas (<1 keV) being due to energy input to the cooling gas rather than to "hiding" the cooling gas.
The Chemical Composition of Comets—Emerging Taxonomies and Natal Heritage

Cometary nuclei contain the least modified material from the formative epoch of our planetary system, and their compositions reflect a range of processes experienced by material prior to its incorporation in the cometary nucleus. Dynamical models suggest that icy bodies in the main cometary reservoirs (Kuiper Belt, Oort Cloud) formed in a range of environments in the protoplanetary disk, and (for the Oort Cloud) even in disks surrounding neighboring stars of the Sun's birth cluster. Photometric and spectroscopic surveys of more than 100 comets have enabled taxonomic groupings based on free radical species and on crystallinity of rocky grains. Since 1985, new surveys have provided emerging taxonomies based on the abundance ratios of primary volatiles. More than 20 primary chemical species are now detected in bright comets. Measurements of nuclear spin ratios (in water, ammonia, and methane) and of isotopic ratios (D/H in water and HCN; 14N/15N in CN and HCN) have provided critical insights on factors affec.
Geometry and interaction of structures in homogeneous isotropic turbulence

Abstract A strategy to extract turbulence structures from direct numerical simulation (DNS) data is described along with a systematic analysis of geometry and spatial distribution of the educed structures. A DNS dataset of decaying homogeneous isotropic turbulence at Reynolds number ${\mathit{Re}}_{\lambda } = 141$ is considered. A bandpass filtering procedure is shown to be effective in extracting enstrophy and dissipation structures with their smallest scales matching the filter width, $L$ . The geometry of these educed structures is characterized and classified through the use of two non-dimensional quantities, ‘planarity’ and ‘filamentarity’, obtained using the Minkowski functionals. The planarity increases gradually by a small amount as $L$ is decreased, and its narrow variation suggests a nearly circular cross-section for the educed structures. The filamentarity increases significantly as $L$ decreases demonstrating that the educed structures become progressively more tubular. An analysis of the preferential alignment between the filtered strain and vorticity fields reveals that vortical structures of a given scale $L$ are most likely to align with the largest extensional strain at a scale 3–5 times larger than $L$ . This is consistent with the classical energy cascade picture, in which vortices of a given scale are stretched by and absorb energy from structures of a somewhat larger scale. The spatial distribution of the educed structures shows that the enstrophy structures at the $5\eta $ scale (where $\eta $ is the Kolmogorov scale) are more concentrated near the ones that are 3–5 times larger, which gives further support to the classical picture. Finally, it is shown by analysing the volume fraction of the educed enstrophy structures that there is a tendency for them to cluster around a larger structure or clusters of larger structures.
On meromorphic maps into the complex projective space

The main purpose of this paper is to give analogous generalizations of the extension theorems and degeneracy theorems of holomorphic maps into the N-dimensional complex projective space $P_{N}(C)$ omitting some hyperplanes given in the previous papers [4] and [5]. Let $\{H_{i} ; 1\leqq i\leqq q\}(q\geqq N+2)$ be hyperplanes in $P_{N}(C)$ located in general position. Associate with each $H_{i}$ a positive integer $m_{i}(\leqq+\infty)$ such that
RETRACTED: Redox Evolution of the Crystallizing Terrestrial Magma Ocean and Its Influence on the Outgassed Atmosphere

Magma oceans (MOs) are episodes of large-scale melting of the mantle of terrestrial planets. The energy delivered by the Moon-forming impact induced a deep MO on the young Earth, corresponding to the last episode of core-mantle equilibration. The crystallization of this MO led to the outgassing of volatiles initially present in the Earth’s mantle, resulting in the formation of a secondary atmosphere. During outgassing, the MO acts as a chemical buffer for the atmosphere via the oxygen fugacity, set by the equilibrium between ferrous- and ferric-iron oxides in the silicate melts. By tracking the evolution of the oxygen fugacity during MO solidification, we model the evolving composition of a C-O-H atmosphere. We use the atmospheric composition to calculate its thermal structure and radiative flux. This allows us to calculate the lifetime of the terrestrial MO. We find that, upon crystallizing, the MO evolves from a mildly reducing to a highly oxidized redox state, thereby transiting from a CO- and H2-dominated atmosphere to a CO2- and H2O-dominated one. We find the overall duration of the MO crystallization to depend mostly on the bulk H content of the mantle, and to remain below 1.5 millions yr for up to nine Earth’s water oceans’ worth of H. Our model also suggests that reduced atmospheres emit lower infrared radiation than oxidized ones, despite of the lower greenhouse effect of reduced species, resulting in a longer MO lifetime in the former case. Although developed for a deep MO on Earth, the framework applies to all terrestrial planet and exoplanet MOs, depending on their volatile budgets.