Miracle-dz/UniFAR-FTUs huggingface dataset:
THEORY OF THE PI JUNCTIONS FORMED IN ATOMIC-SCALE SUPERCONDUCTOR/FERROMAGNET SUPERLATTICES

Using the Green's-functions method we investigate theoretically a model of atomic-scale superconductor/ferromagnet $(S/F)$ superlattices. In this model the phase of the order parameter changes periodically, and the intrinsic phase difference k in the ground state can be zero or \ensuremath{\pi}. Three basic parameters \char22{} the transfer integral t between S and F layers, the exchange field h in $F,$ and the pairing constant $\ensuremath{\Lambda}$ in S \char22{} characterize the system. We find that the critical Josephson current has a nonmonotonic dependence on h, becoming zero at the critical value ${h=h}_{\mathrm{crit}}(T),$ corresponding to the transition between $k=0$ and $k=\ensuremath{\pi}$ in the ground state. We calculate the densities of states on S and F layers and show that the quasiparticle spectra are strongly influenced by the values of h and t.
Uncertainties for two-dimensional models of solar rotation from helioseismic eigenfrequency splitting

Observed solar p-mode frequency splittings can be used to estimate angular velocity as a function of position in the solar interior. Formal uncertainties of such estimates depend on the method of estimation (e.g., least-squares), the distribution of errors in the observations, and the parameterization imposed on the angular velocity. We obtain lower bounds on the uncertainties that do not depend on the method of estimation; the bounds depend on an assumed parameterization, but the fact that they are lower bounds for the 'true' uncertainty does not. Ninety-five percent confidence intervals for estimates of the angular velocity from 1986 Big Bear Solar Observatory (BBSO) data, based on a 3659 element tensor-product cubic-spline parameterization, are everywhere wider than 120 nHz, and exceed 60,000 nHz near the core. When compared with estimates of the solar rotation, these bounds reveal that useful inferences based on pointwise estimates of the angular velocity using 1986 BBSO splitting data are not feasible over most of the Sun's volume. The discouraging size of the uncertainties is due principally to the fact that helioseismic measurements are insensitive to changes in the angular velocity at individual points, so estimates of point values based on splittings are extremely uncertain. Functionals that measure distributed 'smooth' properties are, in general, better constrained than estimates of the rotation at a point. For example, the uncertainties in estimated differences of average rotation between adjacent blocks of about 0.001 solar volumes across the base of the convective zone are much smaller, and one of several estimated differences we compute appears significant at the 95% level.
NMR multiple echoes observed in solid He 3

A large number of echoes-called multiple echoes-following two isolated NMR radio-frequency pulses separated by a time $\ensuremath{\tau}$, have been observed in bcc $^{3}\mathrm{He}$. A quantitative theory of this phenomenon is given, taking into account the nonlinear effect of the nuclear demagnetizing field in the equation of motion of the magnetization. In a magnetic-field gradient $G$, just before the second pulse at time $\ensuremath{\tau}$, the nuclear-spin transverse magnetization has a helical configuration of pitch $\ensuremath{\gamma}G\ensuremath{\tau}={k}_{0}$, which is converted by the second radio-frequency pulse into a sinusoidal modulation of the magnetization along the magnetic field gradient. The corresponding sinusoidal demagnetizing field modulates spatially the NMR resonance frequency so that the transverse magnetization is a superposition of helical configurations with pitch $p{k}_{0}$ (multiple of ${k}_{0}$), yielding multiple echoes at times $p\ensuremath{\tau}$. A detailed comparison with the experimental results obtained at high temperatures ($300 \mathrm{mK}lTl1 \mathrm{K}$) and low temperatures ($1lTl20$ mK), leads to a satisfactory agreement with the experiments. The main practical application of the multiple-echo study is to provide a method of measurement of the absolute value of the nuclear-spin susceptibility without knowing the shape or the number of spins of the sample. The transverse relaxation time ${T}_{2}$ and the diffusion coefficient $D$ are also obtained with this analysis. When applied to the low-temperature measurements, the multiple-echo analysis has pointed out, for the first time, the increase of the magnetic susceptibility of solid $^{3}\mathrm{He}$ in the paramagnetic phase near the ordering temperature ${T}_{c}$, while in contrast the relaxation times ${T}_{1}$ and ${T}_{2}$ and the diffusion coefficient $D$ do not change appreciably, even just above ${T}_{c}$.
STATISTICS OF DENSITY FLUCTUATIONS DURING THE TRANSITION FROM THE OUTER SOLAR CORONA TO THE INTERPLANETARY SPACE

This paper investigates the evolution of the plasma density fluctuations of the fast and slow solar wind from the solar corona into the interplanetary space. The study is performed by comparing the low-frequency spectra and the phase correlation of the proton density oscillations, measured in the inner heliosphere with the Helios 2 in situ instrumentation, with those due to the large-scale density perturbations observed with UVCS/SOHO in the outer corona. We find that the characteristics of density fluctuations of the fast solar wind are maintained in the transition from the outer corona to the inner heliosphere, thus suggesting a coronal imprint for the heliospheric large-scale 1/f2 noise spectrum. In contrast, a quick dynamical evolution is observed in the slow wind, which, starting from large-scale fluctuations with strong phase correlations in the outer corona, gives rise to a Kolmogorov-like spectrum and an accumulation of density structures at small scales at 0.3 AU. This can be explained in the framework of nearly incompressible turbulence.
Spatial anisotropy and rotational invariance of critical hard squares

We develop a new method to analyse solvable models defined on a square lattice rotated through an arbitrary angle phi with respect to the coordinate axes. In the method we introduce auxiliary faces into a rotated system to relate it with an inhomogeneous one in the natural orientation phi =0. The inhomogeneous system is investigated by commuting a transfer matrix argument. As an application of the method, we consider interacting hard squares at the critical point. We discuss relations between spatial anisotropy and rotational (or conformal) invariance of the model in calculations of finite-size properties.
Applications of median filtering to deconvolution, pulse estimation, and statistical editing of seismic data

Methodology for using median filtering as one step in cepstral deconvolution or seismic signature estimation. The surprising conclusion from empirical studies on synthetic data is that in high-noise situations, cepstral-based median filtering appears to perform exceptionally well as a deconvolver but poorly as a signature estimator. --Modified journal abstract.
A Depth-encoded PET Detector

Radial blurring in high-resolution positron emission tomography (PET) can be reduced by measuring the PET photon's depth of interaction within a detector crystal. Simulations show that dividing the crystal into two equiprobable regions of interaction almost eliminates this blurring. This has been done using a black band placed around a 3-cm bismuth germanate crystal, 1 cm from the front. A photomultiplier tube (PMT) collects light from the rear of the crystal for energy and timing measurement. Another PMT collects light through a light guide from the top front of the crystal to find the depth of interaction. Gamma rays interacting in the front of the crystal produce a strong signal in the depth-sensing PMT, while interactions behind the band produce a weaker ( >
Brownian motion of a quantum particle

Proposed here is an exactly soluble model for the field-free motion of a quantum particle interacting with a heat bath. The heat-bath interaction includes a fluctuating random force and a frictional force of Langevin type. The momentum and position distributions obtained in the model have a close relation to the corresponding solutions of the Fokker-Planck equation of a free classical particle.
VECTOR MAGNETIC FIELDS OF A SOLAR POLAR REGION

We study the vector magnetic fields of a solar polar region (PR) based on Solar Optical Telescope/Spectro-Polarimeter measurements. To better understand the polar magnetic properties, we compare the observed polar field with that in two solar quiet regions at the limb (QRL) and the disk center (QRD), and with that in a region of a low-latitude coronal hole (CHR). The following results are discussed: (1) The average vertical flux density of PR is 16 G, while the average horizontal flux density is 91 G. If we assume that the observed polar field suffers the same amount of limb weakening in polarization measurements as the Sun's quiet region, the average unsigned flux density in the pole would be 54 G, 60% stronger than that in the CHR. (2) The kG field in the PR occupies 6.7% of the region. The magnetic filling factor in the PR is characterized by a two-peak distribution, which appears at a field strength close to 100 G and 1000 G, respectively. (3) For the network elements, a correlation holds between the vertical and horizontal flux densities, suggesting the same physical entity is manifested by the observed stronger vertical and horizontal components. (4) The ratio of the magnetic flux in the minority polarity to that in the dominant polarity is approximately 0.5, implying that only 1/3 of the magnetic flux in the PR opens to the interplanetary space. Exemplified with CHR by a quasi-linear force-free extrapolation of the observed magnetic field, we find that the photospheric open flux is not always associated with strong vertical magnetic elements.
Measurement of Third‐Order Elastic Moduli of Yttrium Iron Garnet

The third‐order elastic moduli of yttrium iron garnet (YIG) have been determined from measurements of ultrasonic velocity. A pulsed ultrasonic system which uses a phase comparison principle to measure velocity versus applied stress is described. In units of 1012 dyn/cm2 and for 28°C, the third‐order moduli are: C111=−23.3±0.8C112=−7.17±0.6C123=−0.33±1.3C144=−1.48±0.29C155=−3.06±0.14C456=−0.97±0.16. Thermodynamic definitions for the moduli [K. Brugger, Phys. Rev. 133, A1611 (1964)] have been used.
Rayleigh waves in air saturated axisymmetrical soft porous media

Bulk waves in axisymmetrical poroelastic layers having a given slowness in a plane perpendicular to the symmetry axis of the medium have been previously studied. The previous works are generalized to any angle between the plane where the slowness is defined and the symmetry axis. This allows a description of the Rayleigh waves created by a line source on free surfaces which are not perpendicular to the symmetry axis. An illustration is provided with measurements on a glass wool of the speed of the Rayleigh wave performed in three perpendicular directions and the evaluation of the rigidity parameters of the fibrous medium.
DYNAMICAL AND STATISTICAL MODELS FOR EXPLOITED POPULATIONS †

Human activities have indirectly modified the dynamics of many populations, accelerating considerably the natural rate of species extinction and raising strong concerns about biodiversity. In many such cases, the underlying ‘natural’ dynamics of the population has been modified by human‐induced increases in mortality, even if the populations are not exploited or harvested in the strict sense. Both dynamical and statistical models are needed to investigate the consequences of human‐induced mortality on the overall dynamics of a population. This paper reviews existing approaches and the potential of recent developments to help form a conceptual and practical framework for analysing the dynamics of exploited populations. It examines both the simple case of an extra source of mortality instantaneously in time, and the theory involved when both risks compete over a continuous time scale. This basic theory is expanded to structured populations, using matrix population models, with applications to the conservation biology of long‐lived vertebrates. The type and degree of compensation expected and approaches to detect it are reviewed, and ways of handling uncertainty are discussed.
Fast approximate computation of a time-harmonic scattered field using the on-surface radiation condition method

The numerical study of the on-surface radiation condition method applied to two- and three-dimensional time-harmonic scattering problems is examined. This approach allows us to quickly compute an approximate solution to the initial exact boundary-value problem. A general background for the numerical treatment of arbitrary convex-shaped objects is stated. New efficient on-surface radiation conditions leading in a natural way to a symmetrical boundary variational formulation are introduced. The approximation is based upon boundary finite-element methods. Moreover, this study requires a specific numerical treatment of the curvature operator. To this end, a numerical procedure using some results about the theory of local approximation of surfaces is described. Finally, the effectiveness and generality of the approach is numerically tested for several scatterers.
Deterministic and stochastic analyses of acoustic plane‐wave reflection from inhomogeneous porous seafloor

The propagator matrix technique for the acoustic plane‐wave reflection in layered, porous, anisotropic seafloor is combined with Monte Carlo simulation to investigate the layering effect of the sediment. Statistical data from a geologically known site are processed and used as a benchmark. Realizations of sediment property profiles are generated using a spectral technique. A deterministic analysis demonstrates that the amplitude and phase of reflection coefficient is highly dependent on the variation of porosity. In a stochastic analysis, the effect of randomness is examined. It is found that the fluctuation of the sediment physical properties around a mean profile has a significant influence on the seabed reflectivity, particularly for the incident angles near and above the critical value. Frequency behavior of reflectivity is strongly dependent on the correlation length of medium inhomogeneities. This behavior is attributed to the interaction among different waves that propagate in the porous sediment l.
16S rDNA clone library screening of environmental sample using melting curve analysis

Abstract A new method of screening a 16S rDNA clone library from an environmental sample is demonstrated using the non‐specific fluorescent dye SYBR Green for the melting curve analysis of PCR‐amplified DNA fragments. It is simple, easy and swift to operate. In addition, it requires little manual operation and the product may be still used for further analysis.
Flow physics and RANS modelling of oblique shock/turbulent boundary layer interaction

Abstract Large-eddy simulation (LES) is utilized to investigate flow physics and lower-fidelity modelling assumptions in the simulation of an oblique shock impinging on a supersonic turbulent boundary layer (OSTBLI). A database of LES solutions is presented, covering a range of shock strengths and Reynolds numbers, that is utilized as a surrogate-truth model to explore three topics. First, detailed conservation budgets are extracted within the framework of parametric investigation to identify trends that might be used to mitigate statistical (aleatory) uncertainties in inflow conditions. It is found, for instance, that an increase in Reynolds number does not significantly affect length of separation. Additionally, it is found that variation in the shock-generating wedge angle has the effect of increasing the intensity of low-frequency oscillations and moving these motions towards longer time scales, even when scaled by interaction length. Next, utilizing the LES database, a detailed analysis is performed of several existing models describing the low-frequency unsteady motion of the OSTBLI system. Most significantly, it is observed that the length scale of streamwise coherent structures appears to be dependent on Reynolds number, and at the Reynolds number of the present simulations, these structures do not exist on time scales long enough to be the primary cause of low-frequency unsteadiness. Finally, modelling errors associated with turbulence closures using eddy-viscosity and stress-transport-based Reynolds-averaged Navier–Stokes (RANS) simulations are investigated. It is found that while the stress-transport models offer improved predictions, inadequacies in modelling the turbulence transport terms and the isotropic treatment of the dissipation is seen to limit their accuracy.
Vorticity Coordinates, Transformed Primitive Equations, and a Canonical Form for Balanced Models

Abstract A potential pseudodensity principle is derived for the quasi-static primitive equations on the sphere. An important step in the derivation of this principle is the introduction of “vorticity coordinates”—that is, new coordinates whose Jacobian with respect to the original spherical coordinates is the dimensionless absolute isentropic vorticity. The vorticity coordinates are closely related to Clebsch variables and are the primitive equation generalizations of the geostrophic coordinates used in semigeostrophic theory. The vorticity coordinates can be used to transform the primitive equations into a canonical form. This form is mathematically similar to the geostrophic relation. There is flexibility in the choice of the potential function appearing in the canonical momentum equations. This flexibility can be used to force the vorticity coordinates to move with some desired velocity, which results in an associated simplification of the material derivative operator. The end result is analogous to th.
Minor planets and related objects. XVIII - UBV photometry and surface composition

New photometric observations on the UBV system are presented for 45 asteroids, bringing the total to 91 for which complete UBV colors are available. The reduced magnitudes B (1, 0) scatter about the adopted catalog values by + or - 0m, 25, with negligible systematic difference. The UBV colors fall into three distinct groups which correspond almost perfectly to the S (silicaceous or stony), C (carbonaceous), and U (unclassifiable) asteroid types recently identified from polarimetry, infrared radiometry, and narrow-band spectrophotometry. It becomes possible to classify asteroids from UBV observations alone. The S asteroids have colors very similar to those of L and LL ordinary chondrites, and some of the U objects are consistent in color with nickel-iron or enstatite-rich meteorites, but no meteorites appear to have the UBV colors of the C asteroids. The asteroid C and S compositional types have no exact counterparts among the surfaces of natural satellites.
Space‐resolving flat‐field vacuum ultraviolet spectrograph for plasma diagnostics

A spatial imaging vacuum ultraviolet (VUV) spectrograph has been constructed for simultaneous observation of spatial and spectral distributions of plasma radiation in the wavelength range 150–1050 A. The spectrograph consists of an entrance slit of limited height which provides spatial resolution, an aberration‐corrected concave grating with varied spacing grooves which gives a flat‐field spectral output plane, and an image‐intensified two‐dimensional detector system. The basic characteristics of the spectrograph have been investigated by ray‐tracing calculations. The expected performance has been confirmed through experiments using a dc glow discharge source on the reciprocal dispersion, the spatial resolution, or the incident angle dependence of spectral images. VUV spectra with spatial and time resolution have been obtained successfully in the GAMMA10 tandem mirror experiment.
On the equations defining tangent cones

This paper treats the local study of singularities by means of their tangent cones, more specifically the study of graded rings associated to an ideal of a local ring. We recall some basic facts: let (R, ) be a local ring, I, J ideals of R, such that J ⊆ I; then GR/J(I / J), the graded ring associated to I / J, is canonically isomorphic to the quotient of GR(I) modulo a homogeneous ideal, which is called J*, and which is generated by the so-called ‘initial forms’ of the elements of J. Let us consider the following example: Let k be a field, R = k[X, Y, Z](x, y, Z), I = (X, Y, Z)R, J the prime ideal generated by fl, f2 where f1 = Y3 − Z2, f2 = YZ − X4. Then and it is easily seen that J* properly contains the ideal generated by the initial forms f*1f*2 of f1, f2; namely f*1 = − Z2, f*2 = YZ and (Yf1 + Zf2)* = Y4 ∉ (−Z2, YZ).
A SECOND-ORDER UPWIND LEAST-SQUARES SCHEME FOR INCOMPRESSIBLE FLOWS ON UNSTRUCTURED HYBRID GRIDS

A finite-volume method for the solution of a scalar transport equation in a 2D incompressible fluid flow is presented. The 2D transport equation is solved in a computational domain divided into polygon triangles and quadrilaterals allowing the general use of hybrid structured / unstructured grids. Convection discretization is performed with a new second-order-accurate upwind least-squares scheme (ULSS), and the system of algebraic equations is solved either by the biconjugate gradient stabilized method (BI-CGSTAB) or by the generalized minimal residual method (GMRES). The program language C++ was selected in order to manipulate the mesh data structure easily. Numerical solutions obtained using several different existing convection discretization schemes are compared with analytical solutions of several 2D test cases. The evolution of the error norm slope, as a Junction of the mesh parameters, confirms that the ULSS scheme is second-order accurate to solve 2D scalar transport equations in hybrid structured.
Carbon Star Survey in the Local Group. V. The Outer Disk of M31

We employ the CFH12K mosaic to identify carbon stars, using the R, I, CN, and TiO photometric technique, in a 2240 arcmin2 area, ranging from 17 to 30 kpc of the southwest disk of M31, barely reaching the edge of the observed H I disk. We found 945 C stars with ⟨I0⟩ = 19.94 and σ = 0.47. The surface density of C stars along the major axis of M31 follows an exponential profile with a scale length of 4.85 ± 0.35 kpc, in agreement with adopted values for the scale length of the disk population. Our survey partially overlaps with the recently discovered G1 density enhancement by Ferguson et al. We confirm that no AGB star excess is detectable in the surveyed part of the clump. The C/M ratio, along the major axis, is derived over a distance range of 7 kpc. The strong C/M gradient seen contrasts with results of previous studies of the C stars in M31.
The Acoustical Impedance of an Infinite Hyperbolic Horn

In discussing the acoustical properties of horns, it is in general a mathematical necessity to assume plane waves. In the case of a horn in the form of an hyperboloid of one sheet, however, it is possible to avoid this assumption and to obtain an exact solution to the problem. The analysis, carried through with the aid of the differential analyzer, leads to curves representing the acoustical resistance and reactance as functions of the ratio of the radius of the throat to the wave‐length. Comparison with the conical horn shows that the hyperbolic is superior.