Miracle-dz/UniFAR-FTUs huggingface dataset:
Dark energy and fundamental physics

The acceleration of the expansion of the Universe which has been identified in recent years has deep connections with some of the most central issues in fundamental physics. At present, the most plausible explanation is some form of vacuum energy. The puzzle of vacuum energy is a central question which lies at the interface between quantum theory and general relativity. Solving it will presumably require to construct a quantum theory of gravity and a correspondingly consistent picture of spacetime. To account for the acceleration of the expansion, one may also think of more dynamical forms of energy, what is known as dark energy, or modifications of gravity. In what follows, we review the vacuum energy problem as well as the basic models for dark energy or modification of gravity. We emphasize the conceptual aspects rather than the techniques involved. We also discuss the difficulties encountered in each approach. This review is intended for astrophysicists or physicists not specialized in particle physics, who are interested in apprehending the issues at stake in fundamental physics.
Coupled polarization and acoustic-phonon dynamics after optical excitation of quantum dots near surfaces

An analysis of the pure dephasing of a single quantum dot embedded in a half-space or a free-standing slab due to the interaction of the carriers with confined acoustic phonons is presented. We discuss the time dependence of the polarization and the relative volume change based on exact expressions which hold for ultrafast excitation. We find that the proximity of the quantum dot to a surface leaves distinct traces in the polarization and in the case of the half-space leads to an additional decay. In the case of the slab the polarization shows a pronounced periodic structure depending on the width of the slab.
The alpha dynamo parameter and measurability of helicities in magnetohydrodynamic turbulence

Alpha, an important parameter in dynamo theory, is shown to be proportional to either the kinetic, current, magnetic, or velocity helicities of the fluctuating magnetic field and fluctuating velocity field. The particular helicity to which alpha is proportional depends on the assumptions used in deriving the first‐order smoothed equations that describe the alpha effect. In two cases, viz., when alpha is proportional to either the magnetic helicity or velocity helicity, alpha can be determined experimentally from two‐point measurements of the fluctuating fields in incompressible, homogeneous turbulence with arbitrary rotational symmetry. For the other two possibilities, alpha can be determined if the turbulence is isotropic.
BI CRU : A NEW SYMBIOTIC STAR.

A Mount Stromlo spectrogram of BI Cru taken in 1962 shows emission lines of H I, He I, He II, Fe II, N III, and the forbidden O III, forbidden Ne III, and forbidden S II transitions superposed on a weak bluish continuum. A spectrogram by Allen in 1974 shows emission lines of H I and Fe II and possibly weak He I, forbidden Fe II, and forbidden O I lines superposed on an M-star absorption spectrum. The object is evidently a symbiotic star showing large variations in its spectral character. Significant differences exist in the mean ion velocities and appear to be correlated with ionization potential.
Project Scheduling Under Partially Renewable Resource Constraints

We consider a generalization of the classical resource constrained project scheduling problem. We introduce so-called partially renewable resources by assuming for each resource a capacity on subsets of periods. The concept of partially renewable resources is a fundamental tool in order to make, e.g., timetabling and shift scheduling aspects, amenable to project scheduling. In addition, partially renewable resources serve to model complicated labor regulations. Furthermore, they cover traditional renewable and nonrenewable resource constraints as special cases. We consider makespan minimization as objective. For the exact solution of the problem we employ a basic enumeration scheme. In order to speed up convergence, we formulate bounds which take into account future resource consumption of partially renewable resources. Moreover, we generalize the serial scheduling scheme in order to get fast approximation methods. A rigorous assessment of the procedures is provided by solving ProGen instances generated under a full factorial test design. Besides the well-known problem parameters we employ additionally three parameters which control the generation of partially renewable resources.
Parameterization of the Autoconversion Process. Part I: Analytical Formulation of the Kessler-Type Parameterizations

Abstract Various commonly used Kessler-type parameterizations of the autoconversion of cloud droplets to embryonic raindrops are theoretically derived from the same formalism by applying the generalized mean value theorem for integrals to the general collection equation. The new formalism clearly reveals the approximations and assumptions that are implicitly embedded in these different parameterizations. A new Kessler-type parameterization is further derived by eliminating the incorrect and/or unnecessary assumptions inherent in the existing Kessler-type parameterizations. The new parameterization exhibits a different dependence on liquid water content and droplet concentration, and provides theoretical explanations for the multitude of values assigned to the tunable coefficients associated with the commonly used parameterizations. Relative dispersion of the cloud droplet size distribution (defined as the ratio of the standard deviation to the mean radius of the cloud droplet size distribution) is explici.
Experimental Investigation of Friction Coefficient and Wear Rate of Brass and Bronze under Lubrication Conditions

The present study is conducted in order to compare the frictional and wear behaviour under mixed lubrication of two pins: bronze (CuSn9P) and brass (CuZn39Pb2), sliding on a steel disc (XC42). The selection of this type of brass and bronze was made because they are not large differences in microhardness, however, have a completely different microstructure. All tests were carried out by using a pin-on-disc tribometer, with a plane contact mode and a pure sliding velocity. The results indicate that friction coefficient and the wear coefficient of brass are significantly higher in comparison to bronze for the two studied roughness (Ra = 2 and 0.15 μm). We also note that for the brass the friction is slightly affected by the roughness of the discs, and the running time is reduced. Regarding bronze, the friction passes from 0.17 for the rough disc (Ra = 2 μm) to 0.02 for the smooth disc (Ra = 0.15 μm) with a time of running about 2000 s; the low value of friction corresponds to the transition to a hydrodynamic regime. The analysis of the microstructure of brass shows a high shear of the surface layers, with a severe plastic deformation, which is not the case for the bronze that is not affected by observable deformations.
Frequentist Inference on Random Effects Based on Summarizability

Although Bayesian methodologies have been successful in drawing inference about random effects, the frequentist literature has been limited. In this paper we consider inferences on random effects in hierarchical generalized linear models from a frequentist point of view using their summarizability. We show asymptotic distributional properties for the conditional and the marginal inference when the number of subunits is large. We conduct simulation studies when the number of subunits is small to moderate. A seizure study and an infertility study are used to illustrate the conditional and the marginal inference of random effects.
A Comparison of Neural Network Algorithms and Preprocessing Methods for Star-Galaxy Discrimination

We are interested in examining different artificial intelligence techniques for classifying astronomical objects. In this study we use two different neural networks that utilize supervised learning: learning vector quantization and back-propagation. The networks are trained to distinguish stars and galaxies using an example base of 17 × 17 pixel images consisting of 60 galaxies and 27 stars extracted from the first-generation Digitized Sky Survey. For each neural network we use four different preprocessing methods to create input vectors from the pixelized images. We also use as input the "raw" image data consisting of a 289 (17 × 17) point vector. Our results show that both networks are capable of distinguishing stars and galaxies, with back-propagation working somewhat better in most cases. We discuss the details of the preprocessing methods and which methods work better in which cases.
Faraday rotation in an InP waveguide

Waveguide Faraday rotation was demonstrated in an InP waveguide with magnetic dopants. The modal Verdet coefficient was 10°∕mmT at a wavelength of 1. 55μm. It was found that the Verdet coefficient of the Fe:In1−xGaxAsyP1−y (x=0.290, y=0.628) core was 12.5°∕mmT at a wavelength of 1. 55μm. The Verdet coefficient dependence on wavelength is in agreement with theory. The loss of the waveguide was 4.34dB∕cm, giving a magneto-optic figure of merit of 23 at a magnetic field of 1T and a wavelength of 1. 55μm. This semiconductor waveguide shows promise for monolithically integrated optical isolators.
Analysis and protection of stray light for the space camera at geosynchronous orbit

Stray light is the general term for all non-normal transmission of light in the optical system. The influence of stray light is different according to optical system’s structure. Large area array camera at geosynchronous orbit is facing more serious influence of stray light, especially for the small incident angle of sunlight on the system. It is in dire need of a detailed analysis of stray light of the basic shape of the optical system . In the paper, the influence on the camera used in space from stray light and the necessity to eliminate stray light are presented. The definition of the stray light coefficient and PST(point source transmittance) is briefed. In Tracepro, analysis of the impact of sunlight incident was made at different angles on the space camera, in the case of stray light factor for the quantitative evaluation. The design principle of the inside and outside hood is presented for the R-C (Ritchey Chretien) optical system. On this basis, in order to reduce stray light interference for the space camera, the primary and secondary mirror’s hoods were designed. Finally, when the incidence angle of sunlight is more than 3° incidence on the space camera, the coefficient of stray light is less than 2%. It meets the engineering requirements.
Coherent-Potential Model of Substitutional Disordered Alloys

We introduce a model of a substitutional alloy based on the concept of an effective or coherent potential which, when placed on every site of the alloy lattice, will simulate the electronic properties of the actual alloy. The coherent potential is necessarily a complex, energy-dependent quantity. We evaluate the model for the simple case of a one-dimensional alloy of $\ensuremath{\delta}$-function potentials. In order to provide a basis for comparison, as well as to see if a simpler scheme will suffice, we also calculate the spectrum of the same alloy using the average $t$-matrix approximation introduced by Beeby. On the basis of these results, we conclude that the average $t$-matrix approximation is not adequate for the description of an actual transition-metal alloy, while the coherent-potential picture will provide a more reasonable facsimile of the density of states in such an alloy.
Scattering of a special class of isorefractive spherical objects with spherical anisotropy

The isorefractive scattering by spherically anisotropic spheres is established for the plane‐wave incidence. The effects of the anisotropy ratio in the scattering cross‐sections are studied, and physical insights to particular phenomena are provided. The equivalence in the far‐field scattering is also revealed for both isorefractive and spherically uniaixal anisotropic spheres. The peculiarities in the scattering for both small and large anisotropic spheres and the dependence on spherical anisotropy are presented and discussed. The method developed here thus possesses higher degree of generality and applicability, which can study scattering problems of anisotropic bodies as well as model some physical problems. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 334–338, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24911
Synchronization Phenomena of Two Simple RC Chaotic Circuits Coupled by a Capacitor

In this study, we investigate two coupled chaotic oscillators composed of RC circuits. We carry out computer calculation and circuit experiment. We could observe in-phase synchronization and anti-phase synchronization by computer calculation. Moreover, when we changed the value of coupling strength between oscillators, we observed the change of synchronization state. In addition, we observed in-phase and anti-phase attractor.
Infrared and optical properties of the emission-line galaxies NGC 1386 and NGC 1365

We have obtained optical spectrophotometry and broad-band infrared data for the nucleus of the emission-line galaxy NGC 1386. These observations are discussed and compared with our own optical spectrophotometry as well as published optical and infrared measurements of the nucleus of the neighboring ''hot spot'' galaxy NGC 1365. Both galaxies show large infared excesses. The very high excitation emission-line spectrum of NGC 1386 is that of a type of 2 Seyfert, making this galaxy the closest known member of this class of objects. We find direct evidence for a significant early-type stellar population in the nucleus of NGC 1365, thus strengthening the previous conclusion that the nuclear emission lines of this galaxy are excited by the radiation of young, hot stars. In addition, we confirm the presence of weak (Ne V) and He II emission, which suggests that a nonthermal source of ionization may also be present. The nucleus of NGC 1365 is emitting a factor of 10 more energy in both the optical emission lines and the infrared than is that of NGC 1386. Finally, we point out the uncertainty in identification of NGC 1365 as an X-ray source in view of its proximity of a Seyfert 2, galaxy,more » several of which have now been shown to be strong X-ray emitters. « less
Kinematic Relativity of Quantum Mechanics: Free Particle with Different Boundary Conditions

An investigation of origins of the quantum mechanical momentum operator has shown that it corresponds to the nonrelativistic momentum of classical special relativity theory rather than the relativistic one, as has been unconditionally believed in traditional relativistic quantum mechanics until now. Taking this correspondence into account, relativistic momentum and energy operators are defined. Schr&oumldinger equations with relativistic kinematics are introduced and investigated for a free particle and a particle trapped in the deep potential well.
Exact description of photon migration in isotropically scattering media

An integral equation for the probability density of the photon migration is constructed. The medium is assumed to be infinite and scatter photons isotropically. The solution is found as an expansion over the number of scatterings. The series occurs to converge rapidly suppose the travel time is fixed. The diffusion approximation is obtained from the integral equation in the limit of large travel time t and distance r such that r << t. It is shown that the probability density tends to infinity near the front. The density calculated is compared with the diffusion limit and the results of a method using path integrals. The latter results appear to be generally poorer than the diffusion theory ones, especially near the front.
Null-controllability of discrete-time positive control systems

Abstract The discrete-time linear positive and quasilinear monotone systems are considered. The set of initial points is restricted to be the cone of non-negative vectors. The input belongs to the cone of non-positive vectors. The necessary and sufficient conditions of null-controllability for linear systems are obtained. The conditions are sufficient for quasilinear systems.
LLL ppp and H ¨ older Estimates for Cauchy – Riemann Equations on Convex Domain of Finite/In ﬁ nite Type with Piecewise Smooth Boundary in CCC 2

— In this paper, we investigate L p estimates ( 1 ≤ p ≤ + ∞ ) and f -H ¨ older estimates for the Cauchy – Riemann equation in a class of convex domains of ﬁ nite or in ﬁ nite type with piecewise smooth boundary in C 2
A search for the optical counterpart to PSR B1821-24 in M 28

We have analysed archival HST/WFPC2 images in both the F555W & F814W bands of the core eld of the globular cluster M 28 in an attempt to identify the optical counterpart of the magnetospherically active millisecond pulsar PSR B1821-24. Examination of the radio derived error circle yielded several potential candidates, down to a magnitude of V 24.5 (V0 23.0). Each were further investigated, both in the context of the CMD of M 28, and also with regard to phenomenological models of pulsar magnetospheric emission. The latter was based on both luminosity-spindown correlations and known spectral flux density behaviour in this regime from the small population of optical pulsars observed to date. None of the potential candidates exhibited emission expected from a magnetospherically active pulsar. The fact that the magnetic eld & spin coupling for PSR B1821-24 is of a similar magnitude to that of the Crab pulsar in the vicinity of the light cylinder has suggested that the millisecond pulsar may well be an ecient nonthermal emitter. ASCA's detection of a strong synchrotron-dominated X-ray pulse fraction encourages such a viewpoint. We argue that only future dedicated 2-d high speed photometry observations of the radio error-circle can nally resolve this matter.
Clues from deep HST images to galaxy formation and the role of mergers

We review recent clues from deep HST images on the formation and evolution of galaxies, and the role that mergers have played in this process. First, we first review the evidence from deep ground-based and HST studies for an epoch dependent merger rate, which was higher in the past by ∼(1+z)m with m≃1.5−3 out to z≲1−2. Next, we review clues from deep HST broad-band images to the role of (minor) mergers. The galaxy counts as a function of restframe type show that E/SO’s and Sabc’s are only marginally evolving, but show that Sd/Irr’s are the dominant population for B≲27 mag, or 1≲z≲2. The scale-lengths of all galaxy types decrease steadily towards the faintest flux limits. A significant fraction of the faint blue irregulars have close companions and/or tidal features indicating merging at z≳1.5–2, implying an epoch of merger-induced star-formation for z∼1.5–2, which also coincides with the peak in the star-formation rate [44]. This suggests a Universe at z≳1.5 dominated by hierarchical merging of star-formi.
Super‐resolution through illumination by diffraction‐born evanescent waves

A diffraction grating in silicon with 50 nm lines and spaces is illuminated with diffraction‐born evanescent waves from its transparent replica. A rotation φ between the gratings results in a set of fringes with period λf that is larger than the period of the original gratings by a magnification factor M. These fringes are induced and observed with a photon tunneling microscope having an incident illumination of 650 nm in air. This super‐resolution by what may be considered a form of optical heterodyning with evanescent waves is discussed.
WHY IRREVERSIBILITY? THE FORMULATION OF CLASSICAL AND QUANTUM MECHANICS FOR NONINTEGRABLE SYSTEMS

Nonintegrable Poincare systems with continuous spectrum (so-called Large Poincare Systems, LPS) lead to the appearance of diffusive terms in the framework of dynamics. These terms break time symmetry. They lead, therefore, to limitations to classical trajectory dynamics and of wave functions. These diffusive terms correspond to well-defined classes of dynamical processes (i.e., so-called “vacuum-vacuum” transitions). The diffusive effects are amplified in situations corresponding to persistent interactions. As a result, we have to include already in the fundamental dynamical description the two aspects, probability and irreversibility, which are so conspicuous on the macroscopic level. We have to formulate both classical and quantum mechanics on the Liouville level of probability distributions (or density matrices). For integrable systems, we recover the usual formulations of classical or quantum mechanics. Instead of being irreducible concepts, which cannot be further analyzed, trajectories and wave functions appear as special solutions of the Liouville-von Neumann equations. This extension of classical and quantum dynamics permits us to unify the two concepts of nature we inherited from the 19th century, based on the one hand on dynamical time-reversible laws and on the other on an evolutionary view associated to entropy. It leads also to a unified formulation of quantum theory avoiding the conventional dual structure based on Schrodinger’s equation on the one hand, and on the “collapse” of the wave function on the other. A dynamical interpretation is given to processes such as decoherence or approach to equilibrium without any appeal to extra dynamic considerations (such as the many-world theory, coarse graining or averaging over the environment). There is a striking parallelism between classical and quantum theory. For LPS we have, in general, both a “collapse” of trajectories and of wave functions for LPS. In both cases, we need a generalized formulation of dynamics in terms of probability distributions or density matrices. Since the beginning of this century, we know that classical mechanics had to be generalized to take into account the existence of universal constants. We now see that classical as well as quantum mechanics also have to be extended to include unstable dynamical systems such as LPS. As a result, we achieve a new formulation of "laws of physics" dealing no more with certitudes but with probabilities. The formulation is appropriate to describe an open, evolving universe.
Wavelengths and energy levels of the K i isoelectronic sequence from copper to molybdenum

Seven lines in the K-like transition array 3p63d–3p53d2 were observed for each of the spectra Cu xi to Mo xxiv (except for Rb and Sr) in radiation from impurity-doped tokamak and laser-generated plasmas. Wavelengths in the range of 70–112 A, measured with an uncertainty of ±0.005 A, are given. These are compared with calculations obtained with the relativistic Hartree–Fock code of Cowan [ CowanR. D. , The Theory of Atomic Structure and Spectra ( U. California Press, Berkeley, Calif., 1981)]. From these comparisons, predicted values for the wavelengths of Rb and Sr were obtained, with an uncertainty of ±0.01 A.
Bayesian Estimation of the Size of a Population Under a Sequential Sampling Design

SYNOPTIC ABSTRACT Ahmad, Alalouf and Chaubey (1993, 1999) and Ahmad, Chaubey and Sen (1999) have considered some sequential designs in regard to some finite population problems. Here we give a Bayesian extension to the problem of estimating the size of a population under a sequential design with a natural stopping rule considered in Ahmad, Alalouf and Chaubey (1993). Highlighted among other things is the question of risk robustness with respect to variation in priors.