Miracle-dz/UniFAR-FTUs huggingface dataset:
$ROSAT$-$HRI$ observations of six southern galaxy pairs

We present the detailed analysis of the X{ray data for 6 pairs, isolated or in poor groups, observed at high resolution with the ROSAT HRI . In all cases, the stronger X{ray source is associated with the brighter early-type member and is extended. The extent varies from galactic to group scale, from 3 (RR 210b) to 182 kpc( RR 22a). The fainter members are detected only in two pairs, RR 210 and RR 259. Except for one case, no signicant substructures have been detected in the X{ray maps, possibly also as a consequence of the poor statistics. The core radii of the X{ray surface brightness proles are in the range 1{3 kpc. The distribution of the luminosities of galaxies in pairs encompasses a very wide range of both luminosities and LX=LB ratios, in spite of the very small number of objects studied so far. Our data provide no evidence that pair membership aects the X{ray properties of galaxies. Observation are discussed in the context of the pair/group evolution.
Model of the Jovian magnetic field topology constrained by the Io auroral emissions

[1] The determination of the internal magnetic field of Jupiter has been the object of many studies and publications. These models have been computed from the Pioneer, Voyager, and Ulysses measurements. Some models also use the position of the Io footprints as a constraint: the magnetic field lines mapping to the footprints must have their origins along Io's orbit. The use of this latter constraint to determine the internal magnetic field models greatly improved the modeling of the auroral emissions, in particular the radio ones, which strongly depends on the magnetic field geometry. This constraint is, however, not sufficient for allowing a completely accurate modeling. The fact that the footprint field line should map to a longitude close to Io's was not used, so that the azimuthal component of the magnetic field could not be precisely constrained. Moreover, a recent study showed the presence of a magnetic anomaly in the northern hemisphere, which has never been included in any spherical harmonic decomposition of the internal magnetic field. We compute a decomposition of the Jovian internal magnetic field into spherical harmonics, which allows for a more accurate mapping of the magnetic field lines crossing Io, Europa, and Ganymede orbits to the satellite footprints observed in UV. This model, named VIPAL, is mostly constrained by the Io footprint positions, including the longitudinal constraint, and normalized by the Voyager and Pioneer magnetic field measurements. We show that the surface magnetic fields predicted by our model are more consistent with the observed frequencies of the Jovian radio emissions than those predicted by previous models.
Atomic oxygen in the Martian thermosphere

Modern models of thermospheric composition and temperature and of excitation and radiative transfer processes are used to simulate the O I 130-nm emission from Mars measured by the Mariner 9 ultraviolet spectrometer. We use the Mars thermospheric general circulation model calculations (MTGCM) of Bougher et al. (1988a) and the Monte Carlo partial frequency redistribution multiple scattering code of Meier and Lee (1982). We find that the decline in atomic oxygen through the daylight hours predicted by the MTGCM cannot be reconciled with the excess afternoon brightness seen in the data. Oxygen concentrations inferred from the data show a positive gradient through the day, in agreement with the original analysis by Strickland et al. (1973), although the absolute amounts are somewhat less because we use a larger photoelectron impact excitation and a somewhat larger solar flux in the 130-nm triplet. In addition, the data suggest that the oxygen abundance increases toward high southerly latitudes, in contrast with the MTGCM prediction of high values in the northern (winter) hemisphere. It appears that solar forcing alone cannot account for the observed characteristics of the Martian thermosphere and that wave and tidal effects may profoundly affect the structure, winds, and composition.
A note on the robustness of a full Bayesian method for nonignorable missing data analysis

A full Bayesian method utilizing data augmentation and Gibbs sampling algorithms is presented for analyzing non-ignorable miss- ing data. The discussion focuses on a simplied selection model for re- gression analysis. Regardless of missing mechanisms, it is assumed that missingness only depends on the missing variable itself. Simulation re- sults demonstrate that the simplied selection model can recover re- gression model parameters under both correctly specied situations and many mis-specied situations. The method is also applied to analyzing a training intervention data set with missing data.
Polarization fatigue in PbZr0.45Ti0.55O3-based capacitors studied from high resolution synchrotron x-ray diffraction

High resolution synchrotron x-ray diffraction experiments were performed on (111)-oriented PbZr0.45Ti0. 55O3-based capacitors with a composition in the morphotropic region. Diffraction analyzes were done after bipolar pulses were applied and removed, representing several places in the cyclic switching. Microstructural changes were evidenced from relative diffracted intensities variations of several Bragg reflections and a correlation with the evolution of the ferroelectric responses has been established. First, a peculiar microstructural evolution was observed during the first 3×104 switching cycles and was attributed to the so-called “wake-up” effect. On the other hand, the onset of the fatigue phenomenon was accompanied by significant variations on integrated diffraction intensities. Several mechanisms are proposed and discussed to explain such variations. Finally, the ferroelectric responses were analyzed after x-ray diffraction experiments and compared with those measured before exposure. A detailed an.
Identifying the sources of environmental sounds with a varying number of spectral channels

Normally hearing adult listeners were asked to identify the sources of 60 familiar environmental sounds processed through a vocoder simulation of a cochlear implant with a varying number of frequency channels. Using a Latin square design, listeners heard 10 different sounds in one of the six channel conditions (2, 4, 8, 16, 24, 32) followed by all 60 unprocessed sounds. For each sound, listeners selected one of 60 response options that best described the sound’s source. Preliminary results indicate that (1) source identification accuracy markedly improves up to 16 channels, but does not continue to improve with further increases in the number of channels; (2) individual sounds vary in the number of channels needed for accurate source perception; (3) increasing the number of channels positively affects source identification of some sounds, while it negatively affects others; (4) listeners show different response biases when listening to low versus high number‐of‐channels stimuli; (5) systematic confusion c.
Stability of coalescing binary stars against gravitational collapse: Hydrodynamical simulations

We perform simulations of relativistic binary stars in post-Newtonian gravity to investigate their dynamical stability prior to merger against gravitational collapse in a tidal field. In general, our equations are only strictly accurate to first post-Newtonian order, but they recover full general relativity for spherical, static stars. We study both corotational and irrotational binary configurations of identical stars in circular orbits. We adopt a soft, adiabatic equation of state with $\Gamma = 1.4$, for which the onset of instability occurs at a sufficiently small value of the compaction $M/R$ that a post-Newtonian approximation is quite accurate. For such a soft equation of state there is no innermost stable circular orbit, so that we can study arbitrarily close binaries. This choice still allows us to study all the qualitative features exhibited by any adiabatic equation of state regarding stability against gravitational collapse. We demonstrate that, independent of the internal stellar velocity profile, the tidal field from a binary companion stabilizes a star against gravitational collapse.
Interpreting large scale structure observations

The standard model of large scale structure is considered, in which the structure originates as a Gaussian adiabatic density perturbation with a nearly scale invariant spectrum. The basic theoretical tool of cosmological perturbation theory is described, as well as the possible origin of the density perturbation as a vacuum fluctuation during inflation. Then, after normalising the spectrum to fit the cosmic microwave background anisotropy measured by COBE, some versions of the standard model are compared with a variety of data coming from observations of galaxies and galaxy clusters. The recent COBE analysis of G\'{o}rski and collaborators is used, which gives a significantly higher normalization than earlier ones. The comparison with galaxy and cluster data is done using linear theory, supplemented by the Press-Schechter formula when discussing object abundances of rich clusters and of damped Lyman alpha systems. By focussing on the smoothed density contrast as a function of scale, the observational data can be conveniently illustrated on a single figure, facilitating easy comparison with theory. The spectral index is constrained to $0.6<n<1.1$, and in particle physics motivated models that predict significant gravitational waves the lower limit is tightened to $0.8$. [To appear, Proceedings of Journee Cosmologie, Paris, June 1994]
The Locus of Points of the Hilbert Scheme with Bounded Regularity

In this paper we consider the Hilbert scheme parameterizing subschemes of ℙ n with Hilbert polynomial p(t), and we investigate its locus containing points corresponding to schemes with regularity lower than or equal to a fixed integer r′. This locus is an open subscheme of and, for every s ≥ r′, we describe it as a locally closed subscheme of the Grasmannian given by a set of equations of degree ≤deg(p(t)) +2 and linear inequalities in the coordinates of the Plücker embedding.
Physics of the solar cycle

The theory of the solar/stellar activity cycles is presented, based on the mean-field concept in magnetohydrodynamics. A new approach to the formulation of the electromotive force and the theory of differential rotation and meridional circulation is described. Dynamo cycles in the overshoot layer and distributed dynamos are compared, with the latter including the influence of meridional flow. The overshoot layer dynamo reproduces the solar cycle periods and the butterfly diagram only if alpha=0 in the convection zone (CZ). The distributed dynamo including meridional flows shows the observed butterfly diagram even with a positive dynamo-alpha in CZ. The nonlinear feedback of strong magnetic fields on differential rotation leads to grand minima in the cyclic activity similar to those observed. Our 2D model contains the large- and small-scale feedback of magnetic fields on diff. rotation and induction in a mean-field formulation (Lambda-, alpha-quenching). Grand minima may also occur if a dynamo occasionally falls below its critical eigenvalue. We never found any indication that such an on-off dynamo collapses by this effect after being excited. The full quenching of turbulence by strong magnetic fields as reduced induction (alpha) and reduced turbulent diffusivity (eta_T) is studied in 1D. We find a stronger dependence of cycle period on dynamo number compared with a pure alpha-quenching model giving a very weak cycle period dependence. Also the temporal fluctuations of alpha and eta_T from a random-vortex simulation were applied to a dynamo. Then the low `quality' of the solar cycle can be explained with a small number of giant cells as dynamo-active turbulence. The transition from almost regular magnetic oscillations (many vortices) to a more or less chaotic time series (very few vortices) is shown.
Higher speed VCSELs by photon lifetime reduction

The impedance characteristics and the effects of photon lifetime reduction on the performance of high-speed 850 nm VCSELs are investigated. Through S11 measurements and equivalent circuit modeling we show that the parasitic mesa capacitance can be significantly reduced by using multiple oxide layers. By performing a shallow surface etch (25 - 55 nm) on the fabricated VCSELs, we are able to reduce the photon lifetime by up to 80% and thereby significantly improve both static and dynamic properties of the VCSELs. By optimizing the photon lifetime we are able to enhance the 3dB modulation bandwidth of 7 μm oxide aperture VCSELs from 15 GHz to 23 GHz and finally demonstrate errorfree transmission at up to 40 Gbit/s.
Asymptotic behaviour, with respect to the isothermal compressibility coefficient, for steady flows of weakly compressible viscoelastic fluids

In this paper, we study the behaviour, in terms of compressibility, of steady flows of weakly compressible viscoelastic fluids having a differential constitutive law. The models considered here are Jeffreys’ and Maxwell’s. In both cases, we establish the existence of an asymptotic expansion in the neighbourhood of the steady incompressible fluid flow, with respect to the vanishing isothermal compressibility coefficient.
Noether's theorem in symmetric stochastic calculus of variations

Quite recently, a symmetric stochastic calculus of variations was proposed to formulate canonical stochastic dynamics, which is an extension of Nelson’s stochastic mechanics. In this article a ‘‘Noether’s theorem’’ is formulated within this calculus of variations. Conservation laws of momentum, angular momentum, and energy are proved, which are related with the same laws in quantum mechanics.
Origami-Based Instruction and Junior Secondary School Students’ Academic Performance in Mathematics in Rivers State

- This study investigated Origami-based Instruction and Junior Secondary School Students’ Academic Performance in Mathematics in Rivers State. Two research questions and two null hypotheses were answered and tested respectively. The design of the study was quasi experimental research which involved pretest, treatment and posttest. A sample of 104 students was drawn from a population of 4,584 Junior secondary school one students in government owned secondary schools in Port Harcourt Local Government Area of Rivers State. The research instrument titled Geometry Performance Test was used for data collection. Kuder- Richardson Formula 20 was used to determine the consistency of the instrument and the reliability index of 0.82 was obtained. Mean and standard deviation was used to answer research questions while the null hypotheses were tested using Analysis of Covariance at 0.05 level of significance. Findings showed that students taught with origami-based instructional approach in the experimental group had a higher performance than those taught with chart in the control group with a statistically significant difference. The male students performed better than the female students in the experimental group with no statistically significant difference It was recommended amongst others that origami-based instructional approach should be used to teach Solid Geometry in Junior secondary school one.
IN VITRO CONSERVATION OF THE CRITICALLY ENDANGERED TAXON Convolvulus persicus L . AND REGENERANTS EVALUATION

We had the aim to test in vitro reactivity of Convolvulus persicus for conservative purpose. Fragments of roots, hypocotyls, stem and leaves were used as explants. Modified Chu formula (1978) was used as a base medium owing to the lower content of salts comparing to MS formula. Two main directions of in vitro development were taken into consideration in our experiment: callus induction on auxins added media and shoots development on media supplemented with higher level of cytokinins and lower level of auxins. In vitro developmental processes varied from the induction of a non-regenerative callus or a friable proembryogenic callus, to indirect and direct morphogenesis process, depending on the type of explants and medium variant used. The best regeneration rates were registered in the case of medium Chu supplemented with kinetin (kin) and indole acetic acid (IAA) and active charcoal and medium Chu added with benzyl-amino-purine (BAP), dichlorophenoxyacetic acid (2,4-D) and active charcoal. Several clones were regenerated having the origin in different seeds. The uniformity of the individuals belonging to two different regenerated clones was evaluated using isoenzymes markers as peroxidase, malate-dehydrogenase and isoesterase. Among the analysed biochemical markers, peroxidase showed a relevant spectrum of bands, the regenerants being identical concerning this marker. analiza ţ i, peroxidazele au eviden ţ iat un spectru de benzi relevante, regeneran ţ ii fiind identici. acid, NaCl- sodium chloride, AC- active charcoal.
Do arcs require flat halo cusps

It was recently claimed that several galaxy clusters containing radial and tangential gravitational arcs and having a measured velocity-dispersion profile for the brightest cluster galaxy had to have central density profiles considerably flatter than those found in CDM cluster simulations. Using a simple analytic mass model, we confirm this result for axially symmetric mass distributions. However, we demonstrate that steep density profiles are well in agreement with the cluster requiring the flattest axially symmetric profile once even small deviations from axial symmetry are introduced.
CCD ubvy photometry of the bimodal main-sequence cluster NGC 3680

CCD uvby photometry for the intermediate age, southern open cluster, NGC 3680, is analyzed. For a reddening of E(b-y) = 0.034, a true cluster modulus of 9.74 + or - 0.20 and a cluster metallicity of Fe/H abundance = 0.10 + or - 0.09, based on 18 probable nonbinary members of the cluster brighter than V = 14. The color-magnitude diagram for the cluster suggests that, although the main sequence may be subject to the same bimodal distibution as NGC 752, the likely source in both clusters is a combination of binaries and a sharply curved turnoff. The color-magnitude diagram is compared to the theoretical isochrones of Bertelli et al. (1988), showing an age of (1.9 + or - 0.3) X 10 to the 9th yr. 27 refs.
Resurrection of traditional luminosity evolution models to explain faint fields galaxies

We explore the nature of the evolution of faint field galaxies by assuming that the local luminosity function is not well defined. We use a non-negative least squares technique to derive a near optimal set of local luminosity functions for different spectral types of galaxies by fitting to the observed optical and near-infrared counts, B-R colors, and redshift distributions for galaxies with 15 < B < 27. We report here the results of using only traditional luminosity evolution (ie. the photometric evolution of stars in a galaxy over time given reasonable assumptions of the form of the star formation history for various galaxy types), and simple galaxy reddening and find excellent fits to the observed data to B = 27. We conclude that models more exotic than traditional luminosity evolution are not yet required to explain existing faint field galaxy data and thus the need for contributions by mergers or new populations of galaxies is at least 5x less than previously estimated.
Adaptive Fuzzy Sliding Mode Control for Uncertain Inverted Pendulum System

Firstly, the mathematical model of inverted pendulum system is created. Taking into account the uncertainty of inverted pendulum system external disturbances, adaptive fuzzy sliding mode controller is proposed with sliding mode control (SMC) theory and fuzzy logic theory. This controller can weaken the impact of uncertainty through fuzzification of the switching gain, Owing to Fuzzy approximation of the inverted pendulum system equations for an inverted pendulum with unknown parameters, this system achieve the adaptive control and optimize the control action. Secondly, inverted pendulum system has the features which SMC can keep invariance to the external disturbance and parameter perturbation. Lyapunov function is used to prove the stability of the controller. Simulation results also show that this controller can ensure inverted pendulum system fast response and robustness in the SIMULINK conditions.
A method for calibrating false-match rates in record linkage

Abstract Specifying a record-linkage procedure requires both (1) a method for measuring closeness of agreement between records, typically a scalar weight, and (2) a rule for deciding when to classify records as matches or nonmatches based on the weights. Here we outline a general strategy for the second problem, that is, for accurately estimating false-match rates for each possible cutoff weight. The strategy uses a model where the distribution of observed weights are viewed as a mixture of weights for true matches and weights for false matches. An EM algorithm for fitting mixtures of transformed-normal distributions is used to find posterior modes; associated posterior variability is due to uncertainty about specific normalizing transformations as well as uncertainty in the parameters of the mixture model, the latter being calculated using the SEM algorithm. This mixture-model calibration method is shown to perform well in an applied setting with census data. Further, a simulation experiment reveals that.
Monitoring and predicting rate of VIIRS sensitivity degradation from telescope contamination by tungsten oxide

Shortly after the Earth observations with the VIIRS instrument launched onboard the Suomi NPP spacecraft have begun, it was observed that responsivity of some of the instrument’s spectral bands decreases with time faster than expected. It was determined that the VIIRS telescope mirror contamination with tungsten oxide is the root cause of the degradation, and that the rate of the degradation is controlled by exposure of the mirrors to ultraviolet radiation. We have monitored progress of the degradation using measurements of light reflected from the onboard calibrator’s solar diffuser and taking into account seasonal changes of the solar illumination of the diffuser. The measurements were then used to develop an empirical model of the degradation dynamics and predict future rate of the responsivity changes during the seven-year lifetime of the Suomi NPP mission.
Quantum Monte Carlo simulation of a two-dimensional Bose gas

The equation of state of a homogeneous two-dimensional Bose gas is calculated using quantum Monte Carlo methods. The low-density universal behavior is investigated using different interatomic model potentials, both finite ranged and strictly repulsive and zero ranged, supporting a bound state. The condensate fraction and the pair distribution function are calculated as a function of the gas parameter, ranging from the dilute to the strongly correlated regime. In the case of the zero-range pseudopotential we discuss the stability of the gaslike state for large values of the two-dimensional scattering length, and we calculate the critical density where the system becomes unstable against cluster formation.