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title: Physical aspects of the space-time torsion; abstract: Abstract We review many quantum aspects of torsion theory and discuss the possibility of the space–time torsion to exist and to be detected. The paper starts, in Section 2, with a pedagogical introduction to the classical gravity with torsion, that includes also interaction of torsion with matter fields. Special attention is paid to the conformal properties of the theory. In Section 3, the renormalization of quantum theory of matter fields and related topics, like renormalization group, effective potential and anomalies, are considered. Section 4 is devoted to the action of spinning and spinless particles in a space–time with torsion, and to the discussion of possible physical effects generated by the background torsion. In particular, we review the upper bounds for the magnitude of the background torsion which are known from the literature. In Section 5, the comprehensive study of the possibility of a theory for the propagating completely antisymmetric torsion field is presented. It is supposed that the propagating field should be quantized, and that its quantum effects must be described by, at least, some effective low-energy quantum field theory. We show, that the propagating torsion may be consistent with the principles of quantum theory only in the case when the torsion mass is much greater than the mass of the heaviest fermion coupled to torsion. Then, universality of the fermion–torsion interaction implies that torsion itself has a huge mass, and cannot be observed in realistic experiments. Thus, the theory of quantum matter fields on the classical torsion background can be formulated in a consistent way, while the theory of dynamical torsion meets serious obstacles. In Section 6, we briefly discuss the string-induced torsion and the possibility to induce torsion action and torsion itself through the quantum effects of matter fields. | 162,300 |
title: CFD Modeling of Electrostatic Forces in Gas-Solid Fluidized Beds:; abstract: Electrostatic charges in gas-solid fluidized beds are known to influence the bed dynamics, bubble shape and size, particle agglomeration, segregation and entrainment. In practice, accumulation of electrostatic charges in fluidized beds can lead to operational issues. The present work focuses on the modeling of electrostatics in gas-solid fluidized beds. The particles are assumed to carry a prescribed size-dependent charge, and charge generation and dissipation are not modeled. To consider the effects of bi-polar charging the polarity of the charge carried by fine particles is taken opposite to that of coarse particles. The magnitude of particle charges is approximated to realistic charges reported in the literature. The principal objective is to develop a multi-fluid Euler-Euler model that can describe electrostatic forces on charged particles in gas-solid fluidized beds. The multi-fluid model is solved in a commercial CFD code (ANSYS Fluent 6.3) and uses the kinetic theory of granular flow for calculatin... | 162,301 |
title: ZAPP: The Z Astrophysical Plasma Properties Collaboration.; abstract: The Z Facility at Sandia National Laboratories [Matzen et al., Phys. Plasmas 12, 055503 (2005)] provides MJ-class x-ray sources that can emit powers \u003e0.3 PW. This capability enables benchmark experiments of fundamental material properties in radiation-heated matter at conditions previously unattainable in the laboratory. Experiments on Z can produce uniform, long-lived, and large plasmas with volumes up to 20 cc, temperatures from 1–200 eV, and electron densities from 1017–23 cc−1. These unique characteristics and the ability to radiatively heat multiple experiments in a single shot have led to a new effort called the Z Astrophysical Plasma Properties (ZAPP) collaboration. The focus of the ZAPP collaboration is to reproduce the radiation and material characteristics of astrophysical plasmas as closely as possible in the laboratory and use detailed spectral measurements to strengthen models for atoms in plasmas. Specific issues under investigation include the LTE opacity of iron at stellar-interior conditi... | 162,302 |
title: A new model for gas transport in fractal-like tight porous media; abstract: A new gas transport model for fractal-like tight porous media is proposed by simultaneously considering the microstructural complexity of real porous media, the compressibility of gas, and the gas slippage effect. This model clarifies the gas transport mechanisms in porous media: the total gas flow volume is governed by the weighted addition of viscous flow and slippage flow, and the distribution weighting factor depends on the capillary diameter and the mean free path of the gas. Based on the proposed model, a new permeability model was derived for gas transport in fractal-like tight porous media. The new permeability model does not have any empirical constants, and every parameter in the model has clear physical meaning. The predictions from the model were then compared with experimental data to show that the model is valid. Furthermore, the parameters influencing gas permeability were analyzed. | 162,303 |
title: Near-infrared integral field spectroscopy of star-forming galaxies; abstract: The Palomar Integral Field Spectrograph was used to probe a variety of environments in nine nearby galaxies that span a range of morphological types, luminosities, metallicities, and infrared-to-blue ratios. For the first time, near-infrared spectroscopy was obtained for nuclear or bright H II regions in star-forming galaxies over two spatial dimensions (57 × 100) in the [Fe II] (1.257 μm), [Fe II] (1.644 μm), Paβ (1.282 μm), H2 (2.122 μm), and Brγ (2.166 μm) transition lines. These data yield constraints on various characteristics of the star-forming episodes in these regions, including their strength, maturity, spatial variability, and extinction. The H II regions stand out from the nuclei. Unlike observations of nuclear regions, H II region near-infrared observations do not show a spatial coincidence of the line and continuum emission; the continuum and line maps of H II regions usually show distinct and sometimes spatially separated morphologies. Gauging from Paβ and Brγ equivalent widths and luminosities, the H II regions have younger episodes of star formation than the nuclei and more intense radiation fields. Near-infrared line ratio diagnostics suggest that H II regions have \"purer\" starbursting properties. The correlation between ionizing photon density and mid-infrared color is consistent with the star formation activity level being higher for H II regions than for nuclei. And though the interpretation is complicated, on a purely empirical basis the H II regions show lower Fe1+ abundances than nuclei by an order of magnitude. | 162,304 |
title: Top-charm flavor changing contributions to the effective bsZ vertex; abstract: Abstract We analyze the effects of a tree level flavor changing tcZ vertex induced by a mixing with new isosinglet Q = 2 3 quarks, on the effective bsZ vertex. We compute the contributions arising from the new electroweak penguin diagrams involving one insertion of the tcZ vertex. We show that a generalized GIM mechanism ensures the cancellation of the mass independent terms as well as of the new divergences. Unexpectedly, the presence of a tcZ coupling cannot enhance the rates for the Z mediated flavor changing decays b → s l + l − and b → sν ν - , implying that these processes cannot be used to set limits on the tcZ coupling. The additional effects of the heavy isosinglets are compared with the well studied effects of new isodoublets appearing in multi-generational models. | 162,305 |
title: Direct seawater desalination by ion concentration polarization; abstract: A shortage of fresh water is one of the acute challenges facing the world today. An energy-efficient approach to converting sea water into fresh water could be of substantial benefit, but current desalination methods require high power consumption and operating costs or large-scale infrastructures, which make them difficult to implement in resource-limited settings or in disaster scenarios. Here, we report a process for converting sea water (salinity approximately 500 mM or approximately 30,000 mg l(-1)) to fresh water (salinity \u003c10 mM or \u003c600 mg l(-1)) in which a continuous stream of sea water is divided into desalted and concentrated streams by ion concentration polarization, a phenomenon that occurs when an ion current is passed through ion-selective membranes. During operation, both salts and larger particles (cells, viruses and microorganisms) are pushed away from the membrane (a nanochannel or nanoporous membrane), which significantly reduces the possibility of membrane fouling and salt accumulation, thus avoiding two problems that plague other membrane filtration methods. To implement this approach, a simple microfluidic device was fabricated and shown to be capable of continuous desalination of sea water (approximately 99% salt rejection at 50% recovery rate) at a power consumption of less than 3.5 Wh l(-1), which is comparable to current state-of-the-art systems. Rather than competing with larger desalination plants, the method could be used to make small- or medium-scale systems, with the possibility of battery-powered operation. | 162,306 |
title: Evanescent wave magnetometer; abstract: The authors describe an atomic magnetometer, the evanescent wave magnetometer, which uses an evanescent wave to measure the Larmor frequency of Rb atoms near the cell surface. The submicron penetration depth of the probe beam allows the evanescent wave magnetometer to achieve a spatial resolution of several tens of microns or better, and greatly reduces the inhomogeneous broadeningdue to magnetic field inhomogeneities. Its noise density in the present experiment is ∼100pT∕Hzfor frequencies between 1 and 10mHz, and decreases to less than 10pT∕Hz as the frequency increases to 25Hz. | 162,307 |
title: Simple production of membrane-based LiNbO 3 micro-modulators with integrated tapers; abstract: We report on free-standing electro-optical LiNbO3 waveguides with integrated tapers made by optical grade dicing. Membranes with a calibrated thickness are produced simultaneously with tapers acting as spot-size converters. Thereby, thicknesses from 450 to 500 μm can simply be achieved together with integrated tapers guaranteeing low insertion losses. These developments open the way to the low-cost production of compact and low-power-consuming electro-optical components. As an example, a 200 μm-long free-standing electro-optical Fabry–Perot is demonstrated with a figure of merit of only 0.19 V·cm in a 4.5 μm-thick membrane. | 162,308 |
title: Critical transitions in thin layer turbulence; abstract: We investigate a model of thin layer turbulence that follows the evolution of the two-dimensional motions $\\boldsymbol{u}_{2D}(x,y)$\n along the horizontal directions $(x,y)$\n coupled to a single Fourier mode along the vertical direction ( $z$\n ) of the form $\\boldsymbol{u}_{q}(x,y,z)=[v_{x}(x,y)\\sin (qz),v_{y}(x,y)\\sin (qz),v_{z}(x,y)\\cos (qz)]$\n , reducing thus the system to two coupled, two-dimensional equations. The model, despite its simplicity and ad hoc construction, displays a rich behaviour. Its reduced dimensionality allows a thorough investigation of the transition from a forward to an inverse cascade of energy as the thickness of the layer $H=\\unicode[STIX]{x03C0}/q$\n is varied. Starting from a thick layer and reducing its thickness it is shown that two critical heights are met: (i) one for which the forward unidirectional cascade (similar to three-dimensional turbulence) transitions to a bidirectional cascade transferring energy to both small and large scales and (ii) one for which the bidirectional cascade transitions to a unidirectional inverse cascade when the layer becomes very thin (similar to two-dimensional turbulence). The two critical heights are shown to have different properties close to criticality that we are able to analyse with numerical simulations for a wide range of Reynolds numbers and aspect ratios. | 162,309 |
title: Rayleigh-Taylor-instability experiments with elastic-plastic materials.; abstract: A rotating wheel experimental facility was developed to investigate incompressible Rayleigh-Taylor instability in elastic-plastic materials. A soft solid (mayonnaise) was chosen as the elastic-plastic material for experiments; material properties that include shear modulus and yield strength were fully characterized using a vane spindle type rheometer. Initial perturbations of varying amplitudes and wavelengths were generated on the interface of the soft solid using sinusoidal cutting guides. A backlit imaging technique was used in conjunction with a high-speed camera to track the motion of the interface at various phases of the instability. Results for both two- and three-dimensional perturbations were compared to study the acceleration required for instability and the growth after the interface yielded. Exponential growth rates were observed after instability was reached with trends of increasing growth rates for lower initial amplitudes. It was found that the acceleration required for instability increased when initial amplitude and wavelength decreased. Three-dimensional interfaces were found to be more stable. For both cases, a decrease in initial amplitude produced a more stable interface that increased the threshold acceleration required for the instability. Critical amplitude conditions for instability were calculated and compared with various analytical models and other experimental results. | 162,310 |
title: Simulation and prototyping of 2m long resistive plate chambers for detection of fast neutrons and multi-neutron event identification; abstract: Abstract Resistive plate chamber (RPC) prototypes of 2 m length were simulated and built. The experimental tests using a 31 MeV electron beam, discussed in details, showed an efficiency higher than 90% and an excellent time resolution of around σ = 100 ps . Furthermore, comprehensive simulations were performed by G eant 4 toolkit in order to study the possible use of these RPCs for fast neutron (200 MeV–1 GeV) detection and multi-neutron event identification. The validation of simulation parameters was carried out via a comparison to experimental data. A possible setup for invariant mass spectroscopy of multi-neutron emission is presented and the characteristics are discussed. The results show that the setup has a high detection efficiency. Its capability of determining the momentum of the outgoing neutrons and reconstructing the relative energy between the fragments from nuclear reactions is demonstrated for different scenarios. | 162,311 |
title: Effect of annealing temperature on electrical transport in La2/3Ca1/3MnO3; abstract: Abstract The electrical conductivity of La2/3Ca1/3MnO3 samples prepared using a sol–gel method is shown to be strongly dependent on the annealing temperature (hence the grain size). This is studied using a random resistor-network model in which ferromagnetic metallic particles with the number density p randomly fill the space of sample. The Monte Carlo simulation for the temperature dependence of resistivity shows results in excellent agreement with the experimental data measured in the larger and smaller grain size samples. From this simulation, we find that p is largely decreased for the whole temperature range below the Curie temperature as the grain size decreases. On the basis of temperature dependence of p obtained in the larger and smaller grain size samples, the effect of grain-size on the electrical transport is discussed and a possible explanation is also presented for the grain-size-dependent magnetoresistance behavior. | 162,312 |
title: Computer simulations of particle-bubble interactions and particle sliding using Discrete Element Method; abstract: Abstract Three dimensional Discrete Element Method (DEM) computer simulations have been carried out to analyse the kinetics of collision of multiple particles against a stationary bubble and the sliding of the particles over the bubble surface. This is the first time that a computational analysis of the sliding time and particle packing arrangements of multiple particles on the surface of a bubble has been carried out. The collision kinetics of monodisperse (33 μm in radius) and polydisperse (12–33 μm in radius) particle systems have been analysed in terms of the time taken by 10%, 50% and 100% of the particles to collide against the bubble. The dependencies of these collision times on the strength of hydrophobic interactions follow relationships close to power laws. However, minimal sensitivity of the collision times to particle size was found when linear and square relationships of the hydrophobic force with particles radius were considered. The sliding time for single particles has corroborated published theoretical expressions. Finally, a good qualitative comparison with experiments has been observed with respect to the particle packing at the bottom of the bubble after sliding demonstrating the usefulness of computer simulations in the studies of particle–bubble systems. | 162,313 |
title: Is Gravity Actually the Curvature of Spacetime; abstract: The Einstein equations, apart from being the classical field equations of General Relativity, are also the classical field equations of two other theories of gravity. As the experimental tests of General Relativity are done using the Einstein equations, we do not really know, if gravity is the curvature of a torsionless spacetime, or torsion of a curvatureless spacetime, or if it occurs due to the non-metricity of a curvatureless and torsionless spacetime. However, as the classical actions of all these theories differ from each other by boundary terms, and the Casimir effect is a boundary effect, we propose that a novel gravitational Casimir effect between superconductors can be used to test which of these theories actually describe gravity. | 162,314 |
title: Transmission grating stretcher for contrast enhancement of high power lasers; abstract: We propose, for the first time, a transmission grating stretcher for high power lasers and demonstrate its superiority over conventional, reflective gold grating stretchers in terms of pulse temporal quality. We show that, compared to a conventional stretcher with the same stretching factor, the transmission-grating based stretcher yields more than an order of magnitude improvement in the contrast pedestal. We have also quantitatively characterized the roughness of the grating surfaces and estimated its impact on the contrast pedestal. | 162,315 |
title: R-parity violating chargino decays at the LHC; abstract: Supersymmetric models with R-parity violation (RPV) have become more popular following the lack of any excess of missing energy events at the 8 TeV LHC. To identify such models, the suggested searches generally rely on the decay products of the (effectively) lightest supersymmetric particle (LSP), with signals that depend on the identity of the LSP and the relevant RPV operators. Here we look at the prospects for detecting RPV chargino decays at the LHC and find substantial patches of parameter space in the Minimal Supersymmetric Standard Model with possibly spectacular signatures, such as three charged-lepton resonances. | 162,316 |
title: Investigation of solid-liquid phase change in the spherical capsule using axisymmetric lattice Boltzmann model; abstract: Abstract The solid-liquid phase change process is important to phase change material (PCM). In this paper, in order to investigate the solid-liquid phase change process in a spherical capsule, the axisymmetric lattice Boltzmann (LB) for phase change is proposed firstly. The problems of one-region phase change in cylindrical coordinate system and solid-liquid phase change by convection in cylindrical enclosure have been solved to verify the present LB model. The distributions of outer wall temperature of spherical capsule are linear. The results show that more heat transferred through the upper region of outer wall may enhance the natural convection and accelerate the process of heat transfer. However, the ratio of energy consumed by latent heat decreases with the slope, leading to more non-uniform temperature distribution. Furthermore, when the slope is larger than 0.2547, more heat is applied to rise the temperature of PCM, resulting in the slower melting rate. | 162,317 |
title: Enhancement of Curie temperature and transition temperature range induced by Al doping in Mn1-xAlxCoGe; abstract: Abstract Mn 1-x Al x CoGe alloys with a second order transition were produced by arc-melting method. The substitution of Mn by Al increased the Curie temperature ( T C ) from 260.5 K to 300.8 K, the magnetic entropy change (|Δ S M |) decreased from 3.78 J·Kg −1 K −1 to 2.35 J·Kg −1 K −1 under a field change of Δµ 0 H=5 T. In addition, the |Δ S M | well linearly depends on the H 2/3 around T C . Furthermore, the relative cooling power (RCP) can reach 242.3 J·Kg −1 with a large full width at half maximum of |Δ S M | (75.5 K) for x=0.02. The decrease of |Δ S M | is explained by the corresponding monotonical decrease of magnetic moment per formula unit. | 162,318 |
title: Questioning the equivalence principle; abstract: Abstract The Equivalence Principle (EP) is not one of the ‘universal’ principles of physics (like the action principle). It is a heuristic hypothesis which was introduced by Einstein in 1907, and used by him to construct his theory of general relativity. In modern language, the (Einsteinian) EP consists in assuming that the only long-range field with gravitational-strength couplings to matter is a massless spin-2 field. Modern unification theories, and notably string theory, suggest the existence of new fields (in particular, scalar fields: ‘dilaton’ and ‘moduli’) with gravitational-strength couplings. In most cases the couplings of these new fields ‘violate’ the EP. If the field is long-ranged, these EP violations lead to many observable consequences (variation of ‘constants’, non-universality of free fall, relative drift of atomic clocks, etc.). The best experimental probe of a possible violation of the EP is to compare the free-fall acceleration of different materials. | 162,319 |
title: Combination of lasers and synchrotron radiation in studies of atomic photoionization; abstract: Recent experiments using the combination of conventional lasers and synchrotron radiation are presented and discussed. The controlled laser-manipulation of atoms prior to ionization by the synchrotron radiation provides an ideal experimental basis for detailed investigations of atomic photoionization. Due to the recent advances in high-resolution electron spectroscopy, it has become possible to analyze the J-resolved fine structure of the final ionic states in the photoionization of laser-excited atoms enabling thereby the determination of the specific influence of the outer electron to the ionization from inner subshells. Especially, the analysis of photoemission satellites and their relative intensities bring out directly the importance of electron correlations. Furthermore, it is shown through some examples of experiments using linearly and circularly polarized radiations, how the study of magnetic dichroisms in the photoionization opens the access to a complete description of the photoionization process, in particular to the determination of partial photoionization cross-sections. | 162,320 |
title: Relativistic mean-field theory with non-linear σ and ω terms for neutron stars and supernovae; abstract: Abstract We study the properties of dense matter in neutron stars and supernovae in the relativistic mean-field (RMF) theory with non-linear σ and ω terms. The lagrangian of the RMF theory is motivated by the recent success of the relativistic Brueckner-Hartree-Fock (RBHF) theory. The parameters in the lagrangian are determined by the properties of nuclei including unstable ones and provide the equation of state of nuclear matter similar to the one in the RBHF theory. The proton fraction in neutron-star matter is found to be large enough to allow the direct URCA process for rapid cooling of neutron stars. We calculate nuclear matter having arbitrary proton fractions at finite temperature to provide the equation of state for studies of supernova explosions. The properties of supernova matter containing abundant leptons are studied in detail and the consequences on the gravitational mass of hot neutron stars at the birth era are discussed. | 162,321 |
title: Stark-switching technique for fast quantum gates in Rydberg atoms; abstract: An experiment on Ramsey interferometry of the 37S1/2 → 37P1/2 microwave transition in sodium Rydberg atoms has been performed. Interaction of Rydberg atoms with a cw microwave radiation was effectively controlled by a pulse of weak (\u003c1 V cm−1) electric field, that manipulated the transition frequency near 70 050 MHz. The pulse detuned the microwave radiation from exact resonance, and induced additional phases to the wavefunctions of Rydberg states due to the quadratic Stark shifts. As a result, the Ramsey fringes were observable both on scanning the frequency of the microwave field and on scanning the strength of the electric field pulse. The experiment confirmed that this Stark-switching technique provides a fast and effective control of the atom–light interactions, and preserves the atomic coherence. Possible applications of this technique to experiments on quantum computers are discussed. | 162,322 |
title: Astrophysics with Extraterrestrial Materials; abstract: Extraterrestrial materials, including meteorites, interplanetary dust, and spacecraft-returned asteroidal and cometary samples, provide a record of the starting materials and early evolution of the Solar System. We review how laboratory analyses of these materials provide unique information, complementary to astronomical observations, about a wide variety of stellar, interstellar and protoplanetary processes. Presolar stardust grains retain the isotopic compositions of their stellar sources, mainly asymptotic giant branch stars and Type II supernovae. They serve as direct probes of nucleosynthetic and dust formation processes in stars, galactic chemical evolution, and interstellar dust processing. Extinct radioactivities suggest that the Sun\u0027s birth environment was decoupled from average galactic nucleosynthesis for some tens to hundreds of Myr but was enriched in short-lived isotopes from massive stellar winds or explosions shortly before or during formation of the Solar System. Radiometric dating of met... | 162,323 |
title: Tunable magnetocaloric effect in RTi1−xMoxGe (R = Tb, Er) (x = 0, 0.15) compounds; abstract: The tetragonal layered compounds TbTiGe and ErTiGe order antiferromagnetically at 276 K and 39 K, respectively. Partial substitution of Mo for Ti in these two compounds modifies the magnetic interactions giving rise to a ferromagnetic ground state which results in an enhanced magnetocaloric effect. The magnetic entropy change in ErTi0.85Mo0.15Ge for a magnetic field change of 5 T is ~10.5 J/kg/K as against ~0.8 J/kg/K for ErTiGe in the vicinity of the magnetic transition. Thus, magnetocaloric properties of such layered materials may be tunable by suitable chemical substitutions. | 162,324 |
title: Density and temperature of bosons from quantum fluctuations; abstract: Abstract A method to determine the density and temperature of a system is proposed based on quantum fluctuations typical of bosons in the limit where the temperature T is close to the critical temperature T c for a Bose–Einstein condensate (BEC) at a given density ρ. Quadrupole and particle multiplicity fluctuations using Landauʼs theory of fluctuations near the critical point are derived. As an example, we apply our approach to heavy ion collisions using the Constrained Molecular Dynamics model (CoMD) which includes the Fermi statistics. The model shows some clusterization into deuteron (d) and alpha (α) clusters but it is not enough to reproduce available experimental data. We propose a modification of the collision term in the approach to include the possibility of α–α collisions. The relevant Bose–Einstein factor in the collision term is properly taken into account. This approach increases the yields of bosons relative to fermions closer to data. Boson fluctuations become larger than 1 as expected. If they are confirmed a new field of research could open up for a mixture of strongly interacting fermions and bosons which requires novel techniques both theoretically and experimentally. | 162,325 |
title: Photofission tomography of nuclear waste packages; abstract: Abstract Quantifying the mass of actinides in large concrete waste packages using non-destructive methods is a major challenge for the management and the storage of packages in appropriate facilities. Since the beginning of 1990s, our team in CEA has been working on the development of a method based on interrogation with high-energy photons to assay actinides in large concrete waste package. The method consists in using photons of high energy (bremsstrahlung radiation) in order to induce photofission reactions on the fissile nuclei present in the wastes. The measurement of the delayed neutrons emitted by fission products allows us to quantify the actinides present in the wastes. The accuracy of the method can be deeply improved by carrying out a tomography, i.e. computing the three-dimensional spatial distribution of the actinide mass inside the nuclear waste package. This paper presents the first experimental results of a tomography carried out on a 1.2 t real concrete waste package. Measurements associated with reconstruction algorithms and Monte Carlo simulations have allowed to locate an equivalent mass of 690 mg of uranium 238 centered in a disc of 20–25 cm of diameter at 75 cm height. These measurements have been performed in the SAPHIR irradiation facility at CEA/Saclay. This facility houses a pulsed linear electron accelerator (energy range from 15 to 30 MeV, pulse duration of 2.5 μs, peak current of 130 mA). The located mass has been subsequently confirmed by a destructive analysis of the package. | 162,326 |
title: Nanogranular, Melt-Spun Intermetallic Compound SmNi: Magnetocaloric Effect and Large Coercivity; abstract: Rare earth intermetallic compound SmNi has been synthesized by melt spinning under argon atmosphere. This sample crystallizes in orthorhombic structure (CrB-type, Space group Cmcm, No. 63) and exhibits texture and nanograin formation. The average crystallite size calculated from powder X-ray diffraction data is ~17 nm. Melt-spun SmNi orders ferromagnetically at ~47 K ( $T_{C}$ ) and this is close to $T_{C}$ of the arc-melted sample. The saturation magnetization value at 10 K is only ~0.24 $\\mu _{B}$ /f.u., whereas a large coercivity of ~24 kOe is observed. Isothermal magnetic entropy change, $\\Delta S_{m}$ , shows a maximum at $T_{C}$ , of ~−1 J/kg $\\cdot$ K, for 50 kOe field change with a relative cooling power value of ~10 J/kg. Small moment of Sm, strong magnetocrystalline anisotropy, complex magnetic structure, and nanograin size all influence the magnetism of melt-spun SmNi. | 162,327 |
title: FEW-BODY QUANTUM DYNAMICS IN RELATIVISTIC ION-ATOM COLLISIONS; abstract: Until recently the theory of relativistic ion-atom collisions was basically restricted to the description of the motion of a single electron in the external field generated by the atomic nucleus and that of the ion-projectile. In the present article we review some of the very recent developments in the theory of relativistic ion-atom collisions which go beyond the single-active-electron picture. Here we discuss processes in which two electrons actively participate and focus our attention in the following two kinds of such processes: (i) double ionization of helium by relativistically moving highly charged nuclei and (ii) two-center dielectronic transitions in relativistic collisions between an atom and an ion. | 162,328 |
title: A Universe without expansion; abstract: We discuss a cosmological model where the universe shrinks rather than expands during the radiation and matter dominated periods. Instead, the Planck mass and all particle masses grow exponentially, with the size of atoms shrinking correspondingly. Only dimensionless ratios as the distance between galaxies divided by the atom radius are observable. Then the cosmological increase of this ratio can also be attributed to shrinking atoms. We present a simple model where the masses of particles arise from a scalar \"cosmon\" field, similar to the Higgs scalar. The potential of the cosmon is responsible for inflation and the present dark energy. Our model is compatible with all present observations. While the value of the cosmon field increases, the curvature scalar is almost constant during all cosmological epochs. Cosmology has no big bang singularity. There exist other, equivalent choices of field variables for which the universe shows the usual expansion or is static during the radiation or matter dominated epochs. For those \"field coordinates\" the big bang is singular. Thus the big bang singularity turns out to be related to a singular choice of field coordinates. | 162,329 |
title: Low-Lying Baryons in Hybrid Quark Model; abstract: We study the strong decay processes of the Roper resonance, N*(1440) in the picture of hybrid baryon in which the Roper resonance N*(1440) is interpreted as a state of three quarks and one transverse-electric gluon, q3G. A nonrelativistic quark–gluon model is employed, where the dynamics of antiquark–quark–gluon is described in the effective \\({^{3}S_{1}}\\) vertex in which a quark–antiquark pair is created (destroyed) from (into) a gluon. The wave function of the Roper resonance is properly constructed to take into account the gluon freedom in the nonrelativistic regime. The evaluated strong decay width ratios of N*(1440) are in good agreement with the experimental data. | 162,330 |
title: The IR-Completion of Gravity: What happens at Hubble Scales?; abstract: We have recently proposed an \"Ultra-Strong\" version of the Equivalence Principle (EP) that is not satisfied by standard semiclassical gravity. In the theory that we are conjecturing, the vacuum expectation value of the (bare) energy momentum tensor is exactly the same as in flat space: quartically divergent with the cut-off and with no spacetime dependent (subleading) ter ms. The presence of such terms seems in fact related to some known difficulties, such as the black hole information loss and the cosmological constant problem. Since the terms that we want to get rid of are subleading in the high-momentum expansion, we attempt to explore the conjectured theory by \"IR-completing\" GR. We consider a scalar field in a flat FRW Universe and isolate the first IR-correction to its Fourier modes operators that kills the quadratic (next to leading) time dependent divergence of the stress energy tensor VEV. Analogously to other modifications of field operators that have been proposed in the literature (typically in the UV), the present approach seems to suggest a breakdown (here, in the IR, at large distances) of the metric manifold description. We show that corrections to GR are in fact very tiny, become effective at distances comparable to the inverse curvature and do not contain any adjustable parameter. Finally, we derive some cosmological implications. By studying the consistency of the canonical commutation relations, we infer a correction to the distance between two comoving observers, which grows as the scale factor only when small compared to the Hubble length, but gets relevant corrections otherwise. The corrections to cosmological distance measures are also calculable and, for a spatially flat matter dominated Universe, go in the direction of an effective positive acceleration. | 162,331 |
title: Unstable normal mode for Rayleigh–Taylor instability in viscous fluids; abstract: The character of the growth rates of the normal modes for Rayleigh–Taylor instability of superposed incompressible, viscous fluids is analyzed in terms of appropriately scaled dimensionless parameters and a particularly simple representation of the Rayleigh–Taylor dispersion relation. The chief feature that emerges is that the scaled growth rate is remarkably insensitive to the values of fluid densities and viscosities. To within a few percent, the physical growth rate depends only on the surface tension, the density‐weighted average viscosity, and the effective acceleration. Approximate formulae for the most unstable wavenumber and the corresponding maximum growth rate are given. | 162,332 |
title: Neue Feldgleichungen zur Jordanschen Gravitations-Theorie; abstract: Fur die vonJordan [2] undLudwig [1] entwickelte Theorie wurden vom Verfasser [5] neue Feldgleichungen vorgeschlagen, die hier noch allgemeiner begrundet werden. | 162,333 |
title: Search for light pseudoscalar Higgs bosons in Z decays; abstract: Abstract The possibility of producing light pseudoscalar Higgs bosons, which naturally appear in extensions of the standard model, is analyzed for Z decays. If kinematically allowed, these particles can be produced copiously in association with scalar Higgs bosons in the minimal SUSY extension. Bremsstrahlung off heavy fermions, however, provides access to these particles also in large areas of the parameter space in less constrained models. We discuss the rates and signatures in Z decays and we estimate the range of masses and mixing angles that can be explored at LEP. | 162,334 |
title: Supersymmetry breaking with zero vacuum energy in M-theory flux compactifications.; abstract: An attractive mechanism to break supersymmetry in vacua with zero vacuum energy arose in E{sub 8}xE{sub 8} heterotic models with hidden sector gaugino condensate. An H flux balances the exponentially small condensate on shell and fixes the complex structure moduli. At quantum level this balancing is, however, obstructed by the quantization of the H flux. We show that the warped flux compactification background in heterotic M theory can solve this problem through a warp-factor suppression of the integer flux relative to the condensate. We discuss the suppression mechanism both in the M theory and the four-dimensional effective theory and provide a derivation of the condensate\u0027s superpotential which is free of delta-function squared ambiguities. | 162,335 |
title: Simultaneous Detection of Longitudinal and Transverse Bunch Signals at the KARA Storage Ring; abstract: To understand and control the dynamics in the longitudinal phase space, time-resolved measurements of different bunch parameters are required. For a reconstruction of this phase space, the detector systems have to be synchronized. This reconstruction can be used e.g. for studies of the micro-bunching instability. It occurs if the interaction of the bunch with its own radiation leads to the formation of sub-structures on the longitudinal bunch profile. These sub-structures can grow rapidly -- leading to a sawtooth-like behaviour of the bunch. At KARA, we use a fast-gated intensified camera for energy spread studies, Schottky diodes for coherent synchrotron radiation studies as well as electro-optical spectral decoding for longitudinal bunch profile measurements. For a synchronization, a hardware synchronization scheme is used which compensates for eventual hardware delays. In this paper, the different experimental setups and their synchronization are discussed and first results of synchronous measurements are presented. | 162,336 |
title: Experimental and Numerical Study of Single Bubble Dynamics on a Hydrophobic Surface; abstract: The growth and departure of single bubbles on two smooth surfaces with very different wettabilities are studied using high-speed video microscopy and numerical simulations. Isolated artificial cavities of approximately 10 μm diameter are microfabricated on both a bare and a Teflon-coated silicon substrate to serve as nucleation sites. The bubble departure diameter is observed to be almost 3 times larger and the growth period almost 60 times longer for the hydrophobic surface than for the hydrophilic surface. The waiting period is practically zero for the hydrophobic surface because a small residual bubble nucleus is left behind on the cavity from a previous ebullition cycle. The experimental results are consistent with our numerical simulation results. Bubble nucleation occurs on nominally smooth hydrophobic regions with root mean square roughness (R q ) less than 1 nm even at superheat as small as 3°C. Liquid subcooling significantly affects bubble growth on the hydrophobic surface due to increased bubble surface area. Fundamental understanding of bubble dynamics on heated hydrophobic surfaces will facilitate the development of chemically patterned surfaces with enhanced boiling heat transfer performance and novel phase-change based micro-actuators and energy harvesters. | 162,337 |
title: Determining the Nature of Dark Matter with Astrometry; abstract: We show that measurements of stellar proper motions in dwarf spheroidal galaxies provide a powerful probe of the nature of dark matter. Allowing for general dark matter density profiles and stellar velocity anisotropy profiles, we show that the log slope of the dark matter profile at about twice the stellar core (King) radius can be measured to within ±0.2 when the proper motions of 200 stars are added to standard line-of-sight velocity dispersion data. This measurement of the log slope provides a test of cold and warm dark matter theories at a sensitivity not possible with line-of-sight velocity dispersion measurements alone. The upcoming SIM PlanetQuest will have the sensitivity to obtain the required number of proper motions in Milky Way dwarf spheroidal galaxies. | 162,338 |
title: A dedicated Chandra ACIS observation of the central compact object in the Cassiopeia A supernova remnant; abstract: We present results of a recent Chandra X-ray Observatory observation of the central compact object (CCO) in the supernova remnant Cassiopeia A. This observation was obtained in an instrumental configuration that combines a high spatial resolution with a minimum spectral distortion, and it allowed us to search for pulsations with periods longer than 0.68 s. We found no evidence of extended emission associated with the CCO, nor statistically significant pulsations (the 3-sigma upper limit on pulsed fraction is about 16%). The fits of the CCO spectrum with the power-law model yield a large photon index, Gamma\\approx 5, and a hydrogen column density larger than that obtained from the SNR spectra. The fits with the blackbody model are statistically unacceptable. Better fits are provided by hydrogen or helium neutron star atmosphere models, with the best-fit effective temperature kT_{eff}^\\infty \\approx 0.2 keV, but they require a small star\u0027s radius, R = 4 - 5.5 km, and a low mass, M \u003c 0.8 M_sol. A neutron star cannot have so small radius and mass, but the observed emission might emerge from an atmosphere of a strange quark star. More likely, the CCO could be a neutron star with a nonuniform surface temperature and a low surface magnetic field (the so-called anti-magnetar), similar to three other CCOs for which upper limits on period derivative have been established. The bolometric luminosity, L_{bol}^\\infty \\sim 6\\times 10^{33} erg s^{-1}, estimated from the fits with the hydrogen atmosphere models, is consistent with the standard neutron star cooling for the CCO age of 330 yr. The origin of the surface temperature nonuniformity remains to be understood; it might be caused by anisotropic heat conduction in the neutron star crust with very strong toroidal magnetic fields. | 162,339 |
title: Nucleon-nucleon elastic scattering to 3 GeV; abstract: A partial-wave analysis (PWA) of NN elastic scattering data has been completed. This analysis covers an expanded energy range, from threshold to a laboratory kinetic energy of 3 GeV, in order to include recent elastic pp polarized scattering measurements performed at SATURNE II. Results of the energy-dependent fit are compared with single-energy solutions and Saclay amplitudes obtained via the direct-reconstruction approach. We also comment on the status of {epsilon}{sub 1} in the low-energy region. (c) 2000 The American Physical Society. | 162,340 |
title: Proton-proton scattering above 3 GeV/c; abstract: A large set of data on proton-proton differential cross sections, analyzing powers and the double-polarization parameter ANN is analyzed employing the Regge formalism. We find that the data available at proton beam momenta from 3GeV/c to 50GeV/c exhibit features that are very well in line with the general characteristics of Regge phenomenology and can be described with a model that includes the \\( \\rho\\) , \\( \\omega\\) , f2, and a2 trajectories and single-Pomeron exchange. Additional data, specifically for spin-dependent observables at forward angles, would be very helpful for testing and refining our Regge model. | 162,341 |
title: Exclusive ρ0 meson photoproduction with a leading neutron at HERA: H1 Collaboration; abstract: A first measurement is presented of exclusive photoproduction of ρ0 mesons associated with leading neutrons at HERA. The data were taken with the H1 detector in the years 2006 and 2007 at a centre-of-mass energy of √s=319 GeV and correspond to an integrated luminosity of 1.16 pb-1. The ρ0 mesons with transverse momenta (Formula presented.) GeV are reconstructed from their decays to charged pions, while leading neutrons carrying a large fraction of the incoming proton momentum, (Formula presented.), are detected in the Forward Neutron Calorimeter. The phase space of the measurement is defined by the photon virtuality (Formula presented.), the total energy of the photon–proton system (Formula presented.) GeV and the polar angle of the leading neutron (Formula presented.)0.75 mrad. The cross section of the reaction (Formula presented.) is measured as a function of several variables. The data are interpreted in terms of a double peripheral process, involving pion exchange at the proton vertex followed by elastic photoproduction of a ρ0 meson on the virtual pion. In the framework of one-pion-exchange dominance the elastic cross section of photon-pion scattering, (Formula presented.), is extracted. The value of this cross section indicates significant absorptive corrections for the exclusive reaction (Formula presented.). | 162,342 |
title: High-accuracy waveforms for binary black hole inspiral, merger, and ringdown; abstract: The first spectral numerical simulations of 16 orbits, merger, and ringdown of an equal-mass nonspinning binary black hole system are presented. Gravitational waveforms from these simulations have accumulated numerical phase errors through ringdown of \u003c~0.1 radian when measured from the beginning of the simulation, and \u003c~0.02 radian when waveforms are time and phase shifted to agree at the peak amplitude. The waveform seen by an observer at infinity is determined from waveforms computed at finite radii by an extrapolation process accurate to \u003c~0.01 radian in phase. The phase difference between this waveform at infinity and the waveform measured at a finite radius of r=100M is about half a radian. The ratio of final mass to initial mass is Mf/M=0.951 62±0.000 02, and the final black hole spin is Sf/Mf^2=0.686 46±0.000 04. | 162,343 |
title: The HI Parkes Zone of Avoidance Shallow Survey; abstract: The HI Parkes Zone of Avoidance Survey is a 21 cm blind search with the multibeam receiver on the 64-m radiotelescope, looking for galaxies hidden behind the southern Milky Way. The first, shallow (15 mJy rms) phase of the survey has uncovered 107 galaxies, two-thirds of which were previously unknown. The addition of these galaxies to existing extragalactic catalogs allows the connectivity of a very long, thin filament across the Zone of Avoidance (ZOA) within 3500 km/s to become evident. No local, hidden, very massive objects were uncovered. With similar results in the north (The Dwingeloo Obscured Galaxies Survey) our census of the most dynamically important HI-rich nearby galaxies is now complete, at least for those objects whose HI profiles are not totally buried in the Galactic HI signal. Tests are being devised to better quantify this remaining ZOA for blind HI searches. The full survey is ongoing, and is expected to produce a catalog of thousands of objects when it is finished. | 162,344 |
title: A remotely interrogated all-optical Rb-87 magnetometer; abstract: Atomic magnetometry was performed at Earth’s magnetic field over a free-space distance of ten meters. Two laser beams aimed at a distant alkali-vapor cell excited and detected the 87Rb magnetic resonance, allowing the magnetic field within the cell to be interrogated remotely. Operated as a driven oscillator, the magnetometer measured the geomagnetic field with ≲3.5 pT precision in a ∼2 s data acquisition; this precision was likely limited by ambient field fluctuations. The sensor was also operated in self-oscillating mode with a 5.3 pT/Hz noise floor. Further optimization will yield a high-bandwidth, fully remote magnetometer with sub-pT sensitivity. | 162,345 |
title: Spectral function of the one-dimensional Holstein model at half filling; abstract: The one-electron spectral function of the one-dimensional spin-1/2 Holstein model at half filling is computed by use of the cluster perturbation theory. The cluster Green\u0027s function is obtained by the Lanczos exact diagonalization method within an optimized phonon approach. It is shown that the method allows reliable calculations using a relatively small size cluster and a few optimal phonon bases for the system from weak to strong electron-phonon coupling. In the strong-coupling limit, the spectral function shows the excitation behavior of a bipolaron state with a large gap at the Fermi surface. However, the obtained spectral function displays a metallic character in the weak-coupling regime, which is in accord with the suggestion that the Peierls gap is suppressed by quantum fluctuation of the phonons. | 162,346 |
title: CPsuperH: A Computational tool for Higgs phenomenology in the minimal supersymmetric standard model with explicit CP violation; abstract: Abstract We provide a detailed description of the Fortran code CPsuperH , a newly-developed computational package that calculates the mass spectrum and decay widths of the neutral and charged Higgs bosons in the Minimal Supersymmetric Standard Model with explicit CP violation. The program is based on recent renormalization-group-improved diagrammatic calculations that include dominant higher-order logarithmic and threshold corrections, b-quark Yukawa-coupling resummation effects and Higgs-boson pole-mass shifts. The code CPsuperH is self-contained (with all subroutines included), is easy and fast to run, and is organized to allow further theoretical developments to be easily implemented. 1 The fact that the masses and couplings of the charged and neutral Higgs bosons are computed at a similar high-precision level makes it an attractive tool for Tevatron, LHC and LC studies, also in the CP-conserving case. Program summary Title of program: CPsuperH Catalogue number: ADSR Program summary URL: http://cpc.cs.qub.ac.uk/summaries/ADSR Program obtainable from: CPC Program Library, Queen\u0027s University of Belfast, N. Ireland Computer for which the program is designed and others on which it is operable: PC running under Linux and computers in Unix environment Programming Language used: Fortran77 High-speed storage required: No No. of bytes in distributed program, including test data, etc.: 49 729 Distribution format: tar gzip file No. of lines in combined program and test case: 7417 Separate documentation available: The program and the paper may be obtainable from http://theory.ph.man.ac.uk/~jslee/CPsuperH.html Keywords: Higgs bosons, supersymmetry, CP Nature of physical problem: The mass spectrum, decay widths and branching ratios of the neutral and charged Higgs bosons in the Minimal Supersymmetric Standard Model with explicit CP violation are calculated. The program is based on recent renormalization-group-improved diagrammatic calculations that include dominant higher-order logarithmic and threshold corrections, b-quark Yukawa-coupling resummation effects and Higgs-boson pole-mass shifts. The couplings of the Higgs bosons to the Standard Model gauge bosons and fermions, to their supersymmetric partners and all the trilinear and quartic Higgs-boson self-couplings are also calculated. Method of solution: One-dimensional numerical integration for the Higgs-decay modes involving more than one massive gauge boson, iterative treatment of the threshold corrections, and the numerical diagonalization of the neutralino mass matrix. Restrictions on the complexity of the problem: Only the dominant leading-order QCD corrections which remain unaffected by CP violation have been included in this version. Typical running time: Less than 0.1 s Unusual features of the program: No References: No | 162,347 |
title: Higher order QED corrections to forward-backward asymmetry; abstract: Abstract The problem of evaluating QED radiative corrections to forward-backward asymmetries at LEP/SLC energies is addressed. Using a formalism based on structure functions for initial and final states, a result is derived which includes exact O(α) expression and box-interference corrections as well as resummation to all orders of the radiation. A comparison with the existing calculations is discussed. | 162,348 |
title: IceCube Constraints on Fast-Spinning Pulsars as High-Energy Neutrino Sources; abstract: Relativistic winds of fast-spinning pulsars have been proposed as a potential site for cosmic-ray acceleration from very high energies (VHE) to ultrahigh energies (UHE). We re-examine conditions for high-energy neutrino production, considering the interaction of accelerated particles with baryons of the expanding supernova ejecta and the radiation fields in the wind nebula. We make use of the current IceCube sensitivity in diffusive highenergy neutrino background, in order to constrain the parameter space of the most extreme neutron stars as sources of VHE and UHE cosmic rays. We demonstrate that the current non-observation of 1018 eV neutrinos put stringent constraints on the pulsar scenario. For a given model, birthrates, ejecta mass and acceleration efficiency of the magnetar sources can be constrained. When we assume a proton cosmic ray composition and spherical supernovae ejecta, we find that the IceCube limits almost exclude their significant contribution to the observed UHE cosmic-ray flux. Furthermore, we consider scenarios where a fraction of cosmic rays can escape from jet-like structures piercing the ejecta, without significant interactions. Such scenarios would enable the production of UHE cosmic rays and help remove the tension between their EeV neutrino production and the observational data. | 162,349 |
title: Order and dynamics of intrinsic nanoscale inhomogeneities in manganites; abstract: Neutron elastic, inelastic, and high-energy x-ray scattering techniques are used to explore the nature of the polaron order and dynamics in the colossal magnetoresistive (CMR) system ${\\mathrm{La}}_{0.7}{\\mathrm{Ca}}_{0.3}\\mathrm{Mn}{\\mathrm{O}}_{3}$. Polaron correlations are known to develop within a narrow temperature regime as the Curie temperature is approached from low temperatures, with a nanoscale correlation length that is only weakly temperature dependent. The static nature of these short-range polaron correlations indicates the presence of a glasslike state, very similar to the observations for the bilayer manganite in the metallic-ferromagnetic doping region. In addition to this elastic component, inelastic scattering measurements reveal dynamic correlations with a comparable correlation length and with an energy distribution that is quasielastic. The elastic component disappears at a higher temperature ${T}^{*}$, above which the correlations are purely dynamic. These observations are identical to the polaron dynamics found in the bilayer manganite system in the CMR regime, demonstrating that they are a general phenomenon in the manganites. | 162,350 |
title: Impact Parameter Dependence of Ratio in Probing the Nuclear Symmetry Energy Using Heavy-Ion Collisions; abstract: The impact parameter dependence of ratio is examined in heavy-ion collisions at 400 MeV/nucleon within a transport model. It is shown that the sensitivity of ratio on symmetry energy shows a transition from central to peripheral collisions; that is, the stiffer symmetry energy leads to a larger ratio in peripheral collisions while the softer symmetry energy always leads this ratio to be larger in central collisions. After checking the kinematic energy distribution of ratio, we found this transition of sensitivity of ratio to symmetry energy is mainly from less energetic pions; that is, the softer symmetry energy gets the less energetic pions to form a smaller ratio in peripheral collisions while these pions generate a larger ratio in central collisions. Undoubtedly, the softer symmetry energy can also lead more energetic pions to form a larger ratio in peripheral collisions. Nevertheless, considering that most of pions are insufficiently energetic at this beam energy, we therefore suggest the ratio as a probe of the high-density symmetry energy effective only in central at most to midcentral collisions, thereby avoiding the possible information of low-density symmetry energy carried in ratio from peripheral collisions. | 162,351 |
title: Light-induced orientation in a high glass transition temperature polyimide with polar azo dyes in the side chain; abstract: We report on both polar and nonpolar light-induced orientation of a polyimide of high glass transition temperature (Tg ≈ 210 °C) with nonlinear optical azo dye molecules in the side chain. This photoinduced orientation is shown to occur at room temperature, i.e., at least 190 °C below the Tg value of the polymer, which indicates that the photoisomerization-induced movement of the nonlinear optical chromophores induces, in turn, a movement of the polyimide main chain. This allows for an efficient orientation of the dye molecules in spite of the stiffness of the polyimide main chain. A nonpolar orientation is induced by polarized light irradiation alone, whereas polar orientation is achieved by application of a dc field during the photoisomerization process. Further light irradiation in the absence of a dc field destroys the previously induced stable polar order. A detailed theoretical study of this light-induced depoling process is also presented. | 162,352 |
title: Luminous Red Galaxies: Selection and classification by combining optical and infrared photometry; abstract: We describe a new method of combining optical and infrared photometry to select Luminous Red Galaxies (LRGs) at redshifts $z \u003e 0.6$. We explore this technique using a combination of optical photometry from CFHTLS and HST, infrared photometry from the WISE satellite, and spectroscopic or photometric redshifts from the DEEP2 Galaxy Redshift Survey or COSMOS. We present a variety of methods for testing the success of our selection, and present methods for optimization given a set of rest-frame color and redshift requirements. We have tested this selection in two different regions of the sky, the COSMOS and Extended Groth Strip (EGS) fields, to reduce the effect of cosmic/sample variance. We have used these methods to assemble large samples of LRGs for two different ancillary programs as a part of the SDSS-III/ BOSS spectroscopic survey. This technique is now being used to select $\\sim$600,000 LRG targets for SDSS-IV/eBOSS, which began observations in Fall 2014, and will be adapted for the proposed DESI survey. We have found these methods can select high-redshift LRGs efficiently with minimal stellar contamination; this is extremely difficult to achieve with selections that rely on optical photometry alone. | 162,353 |
title: The density variance-mach number relation in supersonic, isothermal turbulence; abstract: We examine the relation between the density variance and the mean-square Mach number in supersonic, isothermal turbulence, assumed in several recent analytic models of the star formation process. From a series of calculations of supersonic, hydrodynamic turbulence driven using purely solenoidal Fourier modes, we find that the ‘standard’ relationship between the variance in th e log of density and the Mach number squared, i.e., � 2 ln�/¯ = ln 1 + b 2 M 2 � , with b = 1/3 is a good fit to the numerical results in the supersonic regime up to at least Mach 20, similar to previous determinations at lower Mach numbers. While direct measurements of the variance in linear density are found to be severely under estimated by finite resolution effects, it is possible to infer the linear density variance via the assumption of lo g-normality in the Probability Distribution Function. The inferred relationship with Mach number, consistent with ��/¯ � � bM with b = 1/3, is, however, significantly shallower than observational determination s of the relationship in the Taurus Molecular Cloud and IC5146 (both consistent with b � 0.5), implying that additional physics such as gravity is impor tant in these clouds and/or that turbulent driving in the ISM contai ns a significant compressive component. Magnetic fields are not found to change this picture significantly, in g eneral reducing the measured variances and thus worsening the discrepancy with observations. Subject headings: turbulence — ISM: structure — hydrodynamics — stars: formation — magnetohydrodynamics (MHD) — shock waves | 162,354 |
title: Some Hadron Calorimeter Properties Relevant to Storage Rings; abstract: At wide angles in a storage ring environment, a substantial part of the energy seen by a hadron calorimeter can be in the form of very low momentum particles such as jet fragments or resonance cascade decay products. Data are presented on the deviations from Gaussian resolution and linear response for such low momentum particles. The differing responses to incident e-, μ-, π+-, K+-, p and at momenta below 10 GeV/c are also compared. In addition, we discuss the significance of angle effects for a 4π calorimeter, and the problems of combining data from calorimeters with different physical characteristics. Experimental data are presented on the difference in hadron response between a fine grain (\"electromagnetic\") lead calorimeter and a coarser (\"hadron\") iron calorimeter, and on the dependence of the response on the energy sharing between the two calorimeters. | 162,355 |
title: Apparent Non-Coevality among the Stars in Upper Scorpio: Resolving the Problem using a Model of Magnetic Inhibition of Convection; abstract: Two eclipsing binaries in the USco association have recently yielded precise values of masses and radii for 4 low-mass members of the association. Standard evolution models would require these dM4.5 - dM5 stars to have ages which are younger than the ages of more massive stars in the association by factors which appear (in extreme cases) to be as large as ~3. Are the stars in the association therefore non-coeval? We suggest that the answer is No: by incorporating the effects of magnetic inhibition of convective onset, we show that the stars in USco can be restored to coevality provided that the 4 low-mass member stars have vertical surface fields in the range 200 - 700 G. Fields of such magnitude have already been measured on the surface of certain solar-type stars in other young clusters. | 162,356 |
title: Influence of non-magnetic Ti4+ ion doping at Mn site on structural and magnetic properties of La0.67Ba0.33MnO3; abstract: We have investigated the effect of titanium substitution on the structure and the magnetic properties of manganites with La0.67Ba0.33Mn1?xTixO3 (0 ? x ? 0.3) nominal composition. The polycrystalline samples have been produced by the conventional ceramic method at 1523?K. The morphology, grain size and phase identification studies were carried out by scanning electron microscopy, diffraction techniques (neutron and x-ray) and the chemical compositions were precisely determined by the inductively coupled plasma atomic emission spectroscopy technique. The structural refinement at room temperature by the Rietveld method revealed that for x ? 0.1 the compounds are almost a single phase manganite crystallizing in a rhombohedral perovskite structure (LaAlO3 type). The more salient structural feature is an increase in cell parameter and inter-ionic distances with increasing Ti content. For x = 0 and x = 0.05 the samples exhibit two manganite phases with orthorhombic (Imma) and rhombohedral space groups. Compounds with x ? 0.1 are ferromagnetic with a Curie temperature decreasing with increasing x. More complicated magnetic behaviour is observed for larger Ti content. | 162,357 |
title: Testing the multipole structure of compact binaries using gravitational wave observations; abstract: We propose a novel method to test the consistency of the multipole moments of compact binary systems with the predictions of general relativity (GR). The multipole moments of a compact binary system, known in terms of symmetric and trace-free tensors, are used to calculate the gravitational waveforms from compact binaries within the post-Newtonian (PN) formalism. For nonspinning compact binaries, we derive the gravitational wave phasing formula, in the frequency domain, parametrizing each PN order term in terms of the multipole moments which contribute to that order. Using GW observations, this parametrized multipolar phasing would allow us to derive the bounds on possible departures from the multipole structure of GR and hence constrain the parameter space of alternative theories of gravity. We compute the projected accuracies with which the second-generation ground-based detectors, such as the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO), the third-generation detectors such as the Einstein Telescope and Cosmic Explorer, as well as the space-based detector Laser Interferometer Space Antenna (LISA) will be able to measure these multipole parameters. We find that while Advanced LIGO can measure the first two or three multipole coefficients with good accuracy, Cosmic Explorer and the Einstein Telescope may be able to measure the first four multipole coefficients which enter the phasing formula. Intermediate-mass-ratio inspirals, with mass ratios of several tens, in the frequency band of the planned space-based LISA mission should be able to measure all seven multipole coefficients which appear in the 3.5PN phasing formula. Our finding highlights the importance of this class of sources for probing the strong-field gravity regime. The proposed test will facilitate the first probe of the multipolar structure of Einstein’s general relativity. | 162,358 |
title: Assessing the discovery potential of directional detection of dark matter; abstract: There is a worldwide effort toward the development of a large TPC (Time Projection Chamber) devoted to directional Dark Matter detection. All current projects are being designed to fulfill a unique goal : identifying weakly interacting massive particle (WIMP) as such by taking advantage of the expected direction dependence of WIMP-induced events toward the constellation Cygnus. However such proof of discovery requires a careful statistical data treatment. In this paper, the discovery potential of forthcoming directional detectors is adressed by using a frequentist approach based on the profile likelihood ratio test statistic. This allows us to estimate the expected significance of a Dark Matter detection. Moreover, using this powerful test statistic, it is possible to propagate astrophysical and experimental uncertainties in the determination of the discovery potential of a given directional detection experiment. This way, we found that a 30 kg.year CF$_4$ directional experiment could reach a 3$\\sigma$ sensitivity at 90% C.L. down to $10^{-5}$ pb and $3.10^{-4}$ pb for the WIMP-proton axial cross section in the most optimistic and pessimistic scenario respectively. | 162,359 |
title: Soft x-ray polarizer for optical productions of any orthogonal state of the linear and circular polarization modes; abstract: An efficient soft x-ray polarizer that is able to optically convert a linear polarization state to any orthogonal state of not only linear but also circular polarization modes is found by means of numerical calculations of the intensities of individual orthogonal polarization components in reflected waves. Calculation results, using the known linear-polarization-mode based Kerr matrix as well as a newly derived circular-polarization-mode based Kerr matrix, indicate that a +45° or −45° linearly polarized incident wave can be readily converted to any orthogonal states of both circular and linear polarization modes, i.e., left- and right-handed circular and s- and p-linear polarizations through reflection, at certain grazing angles of incidence near the critical angle from a simple ferromagnetic thin film of Co(9.0nm)∕Si substrate. The intensities of almost pure circularly or linearly polarized reflected waves are about 10% or less in a certain spectral soft x-ray range just below the absorption edges of con... | 162,360 |
title: Magnetohydrodynamic pressure drop and flow balancing of liquid metal flow in a prototypic fusion blanket manifold; abstract: Understanding magnetohydrodynamic (MHD) phenomena associated with the flow of electrically conducting fluids in complex geometry ducts subject to a strong magnetic field is required to effectively design liquid metal (LM) blankets for fusion reactors. Particularly, accurately predicting the 3D MHD pressure drop and flow distribution is important. To investigate these topics, we simulate a LM MHD flow through an electrically non-conducting prototypic manifold for a wide range of flow and geometry parameters using a 3D MHD solver, HyPerComp incompressible MHD solver for arbitrary geometry. The reference manifold geometry consists of a rectangular feeding duct which suddenly expands such that the duct thickness in the magnetic field direction abruptly increases by a factor rexp. Downstream of the sudden expansion, the LM is distributed into several parallel channels. As a first step in qualifying the flow, a magnitude of the curl of the induced Lorentz force was used to distinguish between inviscid, irrotati... | 162,361 |
title: Surface-tension-driven convection under the simultaneous action of a magnetic field and rotation; abstract: Abstract Linear stability theory is applied to the problem of surface-tension driven convection when a magnetic field and rotation are simultaneously present. It is shown that the overall behaviour of a fluid is similar to that for the case of buoyancy-driven convection. | 162,362 |
title: The Allegro gravitational wave detector: Data acquisition and analysis.; abstract: We discuss the data acquisition and analysis procedures used on the Allegro gravity wave detector, including a full description of the filtering used for bursts of gravity waves. The uncertainties introduced into timing and signal strength estimates due to stationary noise are measured, giving the windows for both quantities in coincidence searches. | 162,363 |
title: A Galactic short gamma-ray burst as cause for the 14C peak in AD 774/5; abstract: In the last 3000 yr, one significant and rapid increase in the concentration of 14 Ci n tree rings was observed; it corresponds to a γ -ray energy input of 7 × 10 24 erg at Earth within up to one year in AD 774/5. A normal supernova and a solar or stellar flare are unlikely as cause, so that the source remained unknown. Here, we show that a short gamma-ray burst (GRB) in our Galaxy is consistent with all observables: such an event is sufficiently short and provides the necessary energy in the relevant spectral range of γ -rays. Its spectral hardness is consistent with the differential production rates of 14 C and 10 Be as observed. The absence of reports about a historic sighting of a supernova in AD 774/5 or a present-day supernova remnant is also consistent with a short GRB. We estimate the distance towards this short GRB to be ∼1–4 kpc – sufficiently far away, so that no extinction event on Earth was triggered. This is the first evidence for a short GRB in our Galaxy. | 162,364 |
title: Relaxorferroelectrics: An overview; abstract: Abstract The paper will trace the evolution of understanding related to the modification of sharp ferroelectric phase transition behavior that occurs in composition systems which exhibit diffuse and relaxor ferroelectric properties. The focus will be primarily upon the perovskite structure families where cations of different valence occupying similar crystallographic sites in the structure appear to play an important role. Limited ordering in the Pb(B1B2)O3 systems will be discussed and possible mechanisms for self limiting to nanometer scales in some systems explored. New studies of the break up of the simple ferroelectric behavior in lanthanum modified lead zirconate titanate (PLZT) and in lead titanate (PLT) systems will be discussed and the relevance to the general problem of relaxor behavior examined. Evidence for enhanced polarization fluctuations and super paraelectric behavior at high temperatures will be discussed and random field and spin glass models for the lower temperature state considered. ... | 162,365 |
title: Heavy meson production in proton-nucleus reactions with empirical spectral functions; abstract: We study the production of K +, ρ, ω and ϕ mesons in p +12 C reactions on the basis of empirical spectral functions. The high momentum, high removal energy part of the spectral function is found to be negligible in all cases close to the absolute threshold. Furthermore, the two-step process (pN → π N N; π N → N + K +, ρ,ω,ϕ) dominates the cross section at threshold energies in line with earlier calculations based on the folding model. | 162,366 |
title: Electrical conductivity calculations in isochorically heated warm dense aluminum; abstract: We present a theoretical approach to derive the dc conductivity of warm dense matter (WDM) from x-ray Thomson scattering data. Predictions for the conductivity of aluminum at condensed matter densities are given within a wide temperature range ( eV). Strong correlation effects are taken into account by ionic structure factors. Screening and Pauli blocking are described via a pseudopotential. The results are compared with other theoretical models and simulations as well as with experimental measurements in the liquid metal regime and recent experiments in the WDM regime. | 162,367 |
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