Miracle-dz/UniFAR-FTUs huggingface dataset:
Cosmological spatial curvature probed by microwave polarization

If there is a large-scale anisotropy in the expansion of the Universe, the microwave background radiation is expected to be linearly polarized. This Communication shows that spatial curvature is capable of rotating the polarization of the microwaves relative to its direction at last scattering, which is directly correlated with the expansion anisotropy (and so also the observed intensity anisotropy). In Friedmann-Robertson-Walker models of the Universe with additional small expansion anisotropy, the observed rotation relative to the intensity anisotropy would be appreciable and constant over the celestial sphere in the closed (type IX) model, but in the flat and open models, it must either vanish (types I and V) or vary in a complicated way over the celestial sphere (type ${\mathrm{VII}}_{h}$). These facts suggest a clear observational test of the closure of the Universe. Also, an ambiguity inherent in the homogeneity of the Universe does not allow prediction of the direction of rotation; thus homogeneous universes possess a property which might be called "handedness. "
Special Functions and the Theory of Group Representations

A standard scheme for a relation between special functions and group representation theory is the following: certain classes of special functions are interpreted as matrix elements of irreducible representations of a certain Lie group, and then properties of special functions are related to (and derived from) simple well-known facts of representation theory. The book combines the majority of known results in this direction. In particular, the author describes connections between the exponential functions and the additive group of real numbers (Fourier analysis), Legendre and Jacobi polynomials and representations of the group $SU(2)$, and the hypergeometric function and representations of the group $SL(2,R)$, as well as many other classes of special functions.
2-D model reduction by quasi-balanced truncation and singular perturbation

This paper considers two-dimensional system model reduction using 2-D balanced truncation and singular perturbation. A new 2-D state space realization named quasi-balanced realization is proposed which is closely related to a pseudo-balanced realization and a structurally balanced realization. A unique feature of the new balanced realization is that it is numerically efficient when it exists and it reduces to the pseudo-balanced realization if the system is denominator separable. An improved frequency error bound is also derived for the pseudo-balanced (or quasi-balanced) realization model reduction for denominator separable systems. Finally, a new 2-D model reduction method together with stability analysis based on singular perturbation theory is studied. >
Coherent x-ray scattering for discriminating bio-compatible materials in tissue scaffolds

It has been shown that coherently scattered x-rays can be used to discriminate and identify specific components in a mixture of materials. To assess the feasibility of using coherent x-ray scatter (CXS) to characterize the material components within tissue scaffolds, we studied the CXS properties of the bio-compatible materials of polymers (polypropylene fumarate, polycaprolactone, epoxy, etc.), sugar and salt solutions at different concentration, and complex materials consisting of more than one polymer. We also investigated the effects of x-ray spectra on the CXS functions of polymers by measuring them with different x-ray source anodes. It is shown that the synthesized polymers with different portions of base polymers can be characterized with CXS. The polymerization process does not significantly change the CXS characteristics of the measured polymers. When protein is denatured, no substantial change in scatter was detected. Solutions of different concentration can be characterized and quantified by the CXS features corresponding to the solutes. The difference among CXS of solutions of different concentration makes it possible to image and trace fluids and their concentration changes in tissues or scaffolds. Our results show that CXS of complex specimens can be decomposed with the scatter functions of the component materials. By simulating a tissue scaffold with a phantom with several bio-compatible materials, we demonstrated that significant contrast can be achieved at proper scatter angles by measuring the coherent x-ray scatter, despite the low attenuation-based contrast between them. We conclude that use of x-ray scatter makes it possible to track and map the fate (e.g., its breakdown and/or removal) of specific components within tissue scaffolds.
Imposed-dynamo current drive

A mechanism for steady inductive helicity injection (SIHI) current drive has been discovered where the current driving fluctuations are not generated by the plasma but rather are imposed by the injectors. Sheared flow of the electron fluid distorts the imposed fluctuations to drive current. The model accurately predicts the time dependent toroidal current, the injector impedance scaling, and the profile produced in the HIT-SI experiment. These results show that a stable equilibrium can be efficiently sustained with imposed fluctuations and the current profile can, in principle, be controlled. Both are large steps for controlled fusion. Some of the effects of the fluctuations on the confinement of tokamak and spheromak reactors are assessed and the degradation may be tolerable. The mechanism is also of interest to plasma self-organization, fast reconnection and plasma physics in general.
Lithium in the intermediate age cluster NGC 3680: Following Li evolution along the C-M diagram

We present an analysis of high resolution spectroscopic observations (R 30 000, S=N =6 0 150) of 24 members of the intermediate age (1.5 Gyr) open cluster NGC 3680, covering all regions of the cluster colour-magnitude (C{M) diagram where cluster members are known to exist. These observations represent in many aspects challenges to our understanding of stellar interior and mixing. Four main sequence G stars have, within the errors, the same Li abundance, 0.3 dex lower than similar stars in the1 Gyr younger Hyades but comparable with those observed in the coeval cluster IC 4651. The cluster shows a clear Li-dip located around the turn-o; two stars on the upper part of the turn-o are out of the dip and reach solar system meteoritic Li abundances. Just above the turn-o, in a very small range of magnitudes (0.2 in V), a factor of 5L i depletion occurs. This sudden decrease explains puzzling results recently obtained on eld subgiants but it is not at all reproduced by standard (e.g. no rotation, no diusion) models, whereas it is in somewhat better agreement with the predictions of recent models which include rotational mixing and atomic diusion. Out of the six cluster giants, one is probably a binary; of the remaining ve single cluster members, three have a Li abundance log n(Li) 1:1 while two have Li abundances from a factor 6 to more than a factor 30 lower than the other three. The star with no detected Li is the coolest and most luminous object in the sample and is most likely an AGB star; the other has instead a similar magnitude and eective temperature as the three more Li rich giants. The reasons for this dierence in Li abundance among otherwise similar stars can be ascribed either to dierential depletion during main-sequence or post-main sequence evolution, possibly induced by rotation, or to dierences in the evolutionary status of these evolved stars. By comparing our results with those found for clusters of similar age and for eld stars, we nd that none of the possible scenarios gives a fully satisfactory explanation if the present population of NGC 3680 giants reflect the expected ratio of clump vs. rst-ascent RGB stars. If the more abundant Li-rich giants in NGC 3680 are indeed clump giants, their relatively high Li content requires that Li is produced, or brought to the surface, between the tip of the RGB and the clump, which is not consistent with observations of the similar age cluster NGC 752, where the more abundant, presumably clump giants have low Li abundances. Finally, we have used our spectra to determine the metallicity of the cluster giants, nding (Fe=H) = 0:17 0:12. This value is in very good agreement with that derived from spectral indexes analysis, but substantially lower than the value inferred from Stromgren photometry.
Contingent weighting in judgment and choice

Abstract : Preference can be inferred from direct choice between options or from a matching procedure in which the decision maker adjusts one option to match another. Studies of perferences between two-dimensional options (e.g., public policies, job applicants, benefit plans) show that the more prominent dimension looms larger in choice than in matching. Thus, choice is more lexicographic than matching. This finding is viewed as an instance of a general principle of compatibility: the weighting of input is enhanced by their compatibility with the output. To account for such effects, we develop a hierarchy of models in which the tradeoff between attributes is contingent on the nature of the response. The simplest theory of this type, called the contingent weighting model, is applied to the analysis of various compatibility effects, including the choice-matching discrepancy and the preference-reversal phenomenon. These results raise both conceptual and practical questions concerning the nature, the meaning and the assessment of preference.
Smooth Dynamic Factor Analysis with Application to the U.S. Term Structure of Interest Rates

SUMMARY We consider the dynamic factor model and show how smoothness restrictions can be imposed on factor loadings by using cubic spline functions. We develop statistical procedures based on Wald, Lagrange multiplier and likelihood ratio tests for this purpose. The methodology is illustrated by analyzing a newly updated monthly time series panel of US term structure of interest rates. Dynamic factor models with and without smooth loadings are compared with dynamic models based on Nelson–Siegel and cubic spline yield curves. We conclude that smoothness restrictions on factor loadings are supported by the interest rate data and can lead to more accurate forecasts. Copyright © 2013 John Wiley & Sons, Ltd.
NEUTRAL HYDROGEN ASSOCIATED WITH THE S0 GALAXY NGC-1023

NGC 1023, l'une des quelques galaxies lenticulaires riches en gaz actuellement connues a ete observee avec le Radio Telescope de Westerbork. L'hydrogene, qui atteint 1,5×10 9 M ○. , presente une cinematique et une distribution de la densite remarquables qui suggerent une origine intergalactique probable et une arrivee recente. La structure de HI autour de NGC 1023 semble irreguliere et a grumeaux
Ice Nucleation by Aerosol Particles: Experimental Studies Using a Wedge-Shaped Ice Thermal Diffusion Chamber

Abstract The principle and feasibility of a new wedge-shaped ice thermal diffusion chamber are demonstrated and the method of estimating the supersaturation in the chamber is shown. Ice nucleation studies were carried out using the chamber and relatively large aerosol particles freely suspended in air. In the studies, the temperature and the supersaturation were independently controlled without substrate. All natural and artificial, organic and inorganic nuclei studied exhibited condensation-freezing as well as deposition modes of ice formation. Conditions for their occurrence and modes of their activation were identified. A forbidden zone for condensation-freezing nucleation above water saturation was found and its temperature dependency, and the extremely steep rise of nucleation rate when the supersaturation increased beyond it, were determined. A unique deposition nucleation behavior near but below water saturation was confirmed with freely suspended aerosol particles. In contrast with deposition and .
Room temperature magnetism in sputtered (Zn,Co)O films

Cobalt doped zinc oxide films Zn/sub 1-x/Co/sub x/O with the atomic fraction x in the range 0.035-0.115 were prepared by sputtering from composite ZnO/Co/sub 3/O/sub 4/ targets. X-ray diffraction pattern shows the ZnO phase with [002] preferential orientation. Magnetic measurements show ferromagnetic behavior with Curie temperatures higher than 350 K.
New results on the D2Π and B′2Π states of the PO molecule

A rotational analysis of the D–X and D′–X band systems of PO in the region 1900–2100 A has been reinvestigated from an absorption spectrum taken at high resolution. A new ν = 1 vibrational level of the D2Π state of PO interacting with a new vibrational level of the D′2Π state has been studied in detail. Two other new vibrational levels, ν = 2 and 3, of D2Π have been recorded and studied in detail. A rigorous deperturbation of the D and D′ levels has been carried out. It has been shown that D′2Π and B′2Π are one and the same state of the PO molecule. A new band overlapped by the D′–X, 26–0 band has been attributed to the B2Σ+–X2Π transition.
Reduction, analysis, and properties of electric current systems in solar active regions

The specific attraction and, in large part, the significance of solar vector magnetograms lie in the fact that they give the most important data on the electric currents and the nonpotentiality of active regions. Using the vector magnetograms from the Marshall Space Flight Center (MSFC), we employ a unique technique in the area of data analysis for resolving the 180 degree ambiguity in order to calculate the spatial structure of the vertical electric current density. The 180 degree ambiguity is resolved by applying concepts from the nonlinear multivariable optimization theory. The technique is shown to be of particular importance in very nonpotential active regions. The characterization of the vertical electric current density for a set of vector magnetograms using this method then gives the spatial scale, locations, and magnitude of these current systems. The method, which employs an intermediate parametric function which covers the magnetogram and which defines the local "preferred" direction, minimizes a specific functional of the observed transverse magnetic field. The specific functional that is successful is the integral of the square of the vertical current density. We find that the vertical electric current densities have common characteristics for the extended bipolar beta gamma delta-regions studied. The largest current systems have j(sub z)'s which maximizes around 30 mA per square meter and have a linear decreasing distribution to a diameter of 30 Mm.
Nonradial Large Solutions of Sublinear Elliptic Equations

We show that the equation Δu = p(x)f(u) has a positive solution on R N , N ≥ 3, satisfying <artwork name="GAPA31011ei1"> <artwork name="GAPA31011ei2"> if and only if <artwork name="GAPA31011ei3"> when ψ(r) = min{p(x): |x| = r}. The nondecreasing continuous function f satisfies f(0) = 0, f (s) > 0 for s > 0, and sup s ≥ 1 f(s)/s<∞, and the nonnegative continuous function p is required to be asymptotically radial. This extends previous results which required the function p to be constant or radial.
Feature-based ensemble learning for hyperspectral chemical plume detection

Feature-based ensemble learning, where weak hypotheses are learned within the associated feature subspaces constructed by repeated random feature selection, is described. The proposed ensemble approach is less affected by noisy features or outliers unique to the training set than the bagging and boosting algorithms due to the randomized selection of feature subsets from the entire training set. The individual weak hypotheses perform their own generalization processes, within the associated feature subspaces, independently of each other. This allows the proposed ensemble to provide improved performance on unseen data over other ensemble learning methods that randomly choose subsets of training samples in an input space. The weak hypotheses are combined through three different aggregating strategies: majority voting, weighted average and neural network-based aggregation. The proposed ensemble technique has been applied to hyperspectral chemical plume data and a performance comparison of the proposed and other existing ensemble methods is presented.
A comparison of stabilisation approaches for finite-volume simulation of viscoelastic fluid flow

In this work we compare different stabilisation approaches currently used in the simulation of viscoelastic fluid flow. These approaches are: the both-sides diffusion, the positive definiteness preserving scheme, the log-conformation tensor representation and the symmetry factorisation of the conformation tensor. The evaluation of these approaches is done regarding their implementation complexity, stability, accuracy, efficiency and applicability to complex problems. Their performances are examined for an Oldroyd-B fluid in the test cases of lid-driven cavity, flow past a cylinder and 4:1 contraction flow. We summarise the situations in which the different approaches can be recommended.
Crystallographic, magnetic, and ferroelectric structures of bulklike BiFeO3 thin films

BiFeO3 thin films deposited on (111)-SrTiO3 substrates present both structural (rhombohedral) and multiferroic properties similar to bulk. The structural relaxation occurring when thickness increases and the low critical thickness possibly indicate different defect types and distribution as compared to (001)-BiFeO3, which may influence multiferroic domain dynamics. The same G-type antiferromagnetic order as in bulk is observed by neutron diffraction, with a superimposed weak ferromagnetic moment (10emu∕cm3) showing a planar anisotropy of 5kJ∕m3. When doped with 5% Mn these films also exhibit a polarization of 95μC∕cm2 along the [111] direction at room temperature, similar to high-quality BiFeO3 single crystals.
Almost Sure Optimality of Sliding Window Lempel–Ziv Algorithm and Variants Revisited

The sliding window Lempel-Ziv (SWLZ) algorithm has been studied extensively in the information theory literature and has been used in several commercial compression packages. The asymptotic behavior of this algorithm has been studied by Wyner and Ziv and by Shields using different approaches. Shields' results proving asymptotic optimality for all individual sequences with respect to the class of all finite state encoders is known to imply the almost sure asymptotic optimality for the class of stationary and ergodic sources. We establish the almost sure asymptotic optimality (without any mixing conditions) by extending the ideas of Wyner and Ziv using results on recurrence times from ergodic theory. A nonuniversal fixed shift version of the algorithm is introduced to gain more insight into its behavior. Pointwise optimality results are also obtained for several variants based on match-length functions introduced by Gavish and Lempel. We also propose variants of the algorithm for sources with countable alphabet and demonstrate their pointwise optimality.
ON THE SET OF SUMS OF A CONDITIONALLY CONVERGENT SERIES OF FUNCTIONS

This article concerns questions connected with the structure of the set of sums of series in a Banach space, i.e., the set of all limit functions for convergent rearrangements of a given series. It is proved that in any Banach space there exist series for which the set of sums consists of two points, series for which it forms a finite or infinite arithmetic progression, and series for which it is a finite-dimensional lattice. Stronger results are obtained separately for the spaces Lp(0, 1) with 1 ≤ p < ∞ and for convergence in measure of series of functions. Bibliography: 5 titles.
Separation criterion for turbulent boundary layers via similarity analysis

By using the RANS boundary layer equations, it will be shown that the outer part of an adverse pressure gradient turbulent boundary layer tends to remain in equilibrium similarity, even near and past separation. Such boundary layers are characterized by a single and constant pressure gradient parameter, and its value appears to be the same for all adverse pressure gradient flows, including those with eventual separation
An Alternative Approach to Detection of Length-Related Biases in Standard Weight Equations

Abstract We propose a new method for assessing length-related biases in standard weight (W s) equations computed by the regression-line−percentile method. We evaluated the performance of the new method relative to two previous methods for assessing length-related biases using 15 data sets from which W s equations have been computed. The new method detected potentially serious length-related biases in 10 W s equations, whereas one of the previously used methods failed to detect any biologically significant biases and the other method detected biases in only one equation. The new method can detect curvilinear relationships between W s and length, so it provides insight that is not available from previous methods.
Spatial and Temporal Contrast-Sensitivity Functions of the Visual System

T HE dependence of the form of the spatial contrast-sensitivity function for a square-wave test grating upon the duration of exposure of the target has been investigated by Schober and Hilz. 1 Kelly 2 has pointed out an analogous dependence of the form of the temporal contrast (modulation) sensitivity function upon the angular extent of the test target. The reciprocal nature of these spatio-temporal interactions can be particularly clearly ap­ preciated if the threshold contrast is determined for a grating target whose luminance perpendicular to the bars is given by where m is the contrast, v the spatial frequency, and ƒ the temporal frequency of the target. FIG. 2. Temporal contrast-sensitivity (reciprocal of threshold contrast) functions for different spatial frequencies. The points are the means of four measurements and the curves (two with dashed low-frequency sections) differ only in their positions along the contrast-sensitivity scale, O 0.5 cycle per degree, ● 4, ∆ 16, ▲ 22 cycles per degree. FIG. 1. Spatial contrast-sensitivity (reciprocal of threshold contrast) functions for different temporal frequencies. The points are the means of four measurements and the curves (one with a dashed low-frequency section) differ only in their positions along the contrast-sensitivity scale O 1 cycle per second, ● 6, ∆ 16, ▲ 22 cycles per second. Such a pattern was set up as a display on a cathode-ray oscil­ loscope and Figs. 1 and 2 show the results of threshold-contrast measurements made by the author (a well-corrected myope). Viewing was binocular at a distance of 2 m. The grating pattern subtended 2.5°×2.5° in the center of a 10°× 10° screen illuminated to the same mean luminance of 20 cd/m 2. The general similarity of the two sets of contrast-sensitivity functions is immediately evident but two features are particularly remarkable. First, the form of the fall-off in sensitivity at high
On implicit subgrid-scale modeling in wall-bounded flows

Approaches to large eddy simulation where subgrid-scale model and numerical discretization are fully merged are called implicit large eddy simulation (ILES). Recently, we have proposed a systematic framework for development, analysis, and optimization of nonlinear discretization schemes for ILES [Hickel et al., J. Comput. Phys. 213, 413(2006)]. The resulting adaptive local deconvolution method (ALDM) provides a truncation error which acts as a subgrid-scale model consistent with asymptotic turbulence theory. In the present paper ALDM is applied to incompressible, turbulent channel flow to analyze the implicit model for wall-bounded turbulence. Computational results are presented for Reynolds numbers, based on friction velocity and channel half-width, of Reτ=180, Reτ=395, Reτ=590, and Reτ=950. All simulations compare well with direct numerical simulation data and yield better results than the dynamic Smagorinsky model at the same resolution. The results demonstrate that the implicit model ALDM provides an .