text
stringlengths 135
9.96k
| idx
int64 0
162k
|
|---|---|
title: Magneto-optical study of the colossal magneto-resistance pyrochlore Tl2Mn2O7; abstract: Pyrochlore Tl 2 Mn 2 O 7 has been found to exhibit a colossal magneto-resistance (CMR) that is comparable to that for the perovskite manganites such as La 1-x Sr x MnO 3 . In order to probe the microscopic electronic structures of Tl 2 Mn 2 O 7 , we have measured its optical conductivity σ(ω) in wide ranges of photon energy, temperature (T), and external magnetic field (B). We have observed very strong variations of σ(ω) with T and B near the Curie temperature, where the CMR manifests itself. Analyses on the variations in σ(ω) show that both T- and B-induced evolutions of the electronic structures in Tl 2 Mn 2 O 7 are very similar to each other, and that they are universally related to the development of macroscopic magnetization. We have also observed a pronounced Kerr rotation at the plasma edge of the reflectivity. | 161,800 |
title: Type Ia Supernovae: Non-standard Candles of the Universe; abstract: We analyze the influence of the evolution of light absorption by gray dust in the host galaxies of type Ia supernovae (SNe Ia) and the evolution of the mean combined mass of close-binary carbon-oxygen white dwarfs merging due to gravitational waves (SNe Ia precursors) on the interpretation of Hubble diagrams for SNe Ia. A significant increase in the mean SNe Ia energy due to the higher combined masses of merging dwarfs should be observable at redshifts z \u003e 2. The observed relation between the distance moduli and redshifts of SNe Ia can be interpreted not only as evidence for accelerated expansion of the Universe, but also as indicating time variations of the gray-dust absorption of light from these supernovae in various types of host galaxies, observational selection effects, and the decrease in mean combined masses of merging degenerate dwarfs. | 161,801 |
title: Noise Prediction for Increasingly Complex Jets. Part II: Applications:; abstract: The numerical system described in Part I (Ref. 1) is applied to a variety of cases which increase difficulty, and progress in the direction of the complete simulation of an airliner engine. The grids have on the order of 1 million points. In many cases, the system meets the 2-3 dB accuracy target both in terms of directivity and of spectrum, up to a Strouhal number of about 1.5. The jet Mach number is varied from 0.3 to slightly supersonic with under-expansion, generating shock cells and greatly increasing side-line noise. For heated jets, the cross-effect between the acoustic Mach number and the temperature is correctly reproduced. Jets placed in a co-flowing stream with velocity up to 60% of the jet\u0027s are studied and found to sustain natural transition without unsteady forcing; the noise trends are correct. Finally, \"synthetic chevrons\" are added by altering the inflow conditions, and found to reduce low-frequency noise while increasing mid-frequency noise. In total, about fifteen meaningfully different... | 161,802 |
title: Magnetic Phase Diagram and Metal-Insulator Transition of NiS2 xSex; abstract: Magnetic phase diagram of NiS 2- x Se x has been reexamined by systematic studies of electrical resistivity, uniform magnetic susceptibility and neutron diffraction using single crystals grown by a chemical transport method. The electrical resistivity and the uniform magnetic susceptibility exhibit the same feature of temperature dependence over a wide Se concentration. A distinct first order metal-insulator (M-I) transition accompanied by a volume change was observed only in the antiferromagnetic ordered phase for 0.50≤ x ≤0.59. In this region, the M-I transition makes substantial effects to the thermal evolution of staggered moments. In the paramagnetic phase, the M-I transition becomes broad; both the electrical resistivity and the uniform magnetic susceptibility exhibit a broad maximum around the temperatures on the M-I transition-line extrapolated to the paramagnetic phase. | 161,803 |
title: LATTICE BOLTZMANN DYNAMICS AND DYNAMICAL SYSTEM SUB-GRID MODELS; abstract: The dynamics sub-grid scale (SGS) models and the dynamical system SGS model are introduced into the lattice Boltzmann method (LBM), and applied to numerical simulation of turbulent cavity flows. The results are compared with those of direct numerical simulation of turbulence and Smagorinsky SGS model. A new average method of eliminating the inherent unphysical oscillation of LBM is also given. | 161,804 |
title: A new test of general relativity; abstract: The emission of gravitational radiation by the recently discovered binary pulsar system will cause its orbital periodP to decrease at a rate which can now be predicted to beP−1dP/dt= −(3 ± 2) × 10−9yr−1 if the only orbital perturbations are of general-relativistic origin. It is shown that other sources of period change are probably less important. The accuracy of this prediction as well as the possibility of its verification will improve greatly over the next few years. This is the first observation that can test general relativity beyond the post-Newtonian approximation. | 161,805 |
title: Next-to-Leading-Order Monte Carlo Simulation of Diphoton Production in Hadronic Collisions; abstract: We present a method, based on the positive weight next-to-leading-order matching formalism (POWHEG), to simulate photon production processes at next-to- leading-order (NLO). This technique is applied to the simulation of diphoton production in hadron-hadron collisions. The algorithm consistently combines the parton shower and NLO calculation, producing only positive weight events. The simulation includes both the photon fragmentation contribution and a full implementation of the truncated shower required to correctly describe soft emissions in an angular-ordered parton shower. | 161,806 |
title: Jacobian free global event analysis; abstract: Abstract Conventional global event analysis using the sphericity tensor is shown to be biased against shapes with degenerate radii and vanishing flow angles for multiplicities M O ( 1 M ) distortions. Finally, an azimuthally corrected sphericity matrix is shown to be useful in searching for collective flow phenomena in nuclear collisions. | 161,807 |
title: Signatures of hypermassive neutron star lifetimes on r-process nucleosynthesis in the disc ejecta from neutron star mergers; abstract: We investigate the nucleosynthesis of heavy elements in the winds ejected by accretion discs formed in neutron star mergers. We compute the element formation in disc outflows from hypermassive neutron star (HMNS) remnants of variable lifetime, including the effect of angular momentum transport in the disc evolution. We employ long-term axisymmetric hydrodynamic disc simulations to model the ejecta, and compute r-process nucleosynthesis with tracer particles using a nuclear reaction network containing ∼8000 species. We find that the previously known strong correlation between HMNS lifetime, ejected mass and average electron fraction in the outflow is directly related to the amount of neutrino irradiation on the disc, which dominates mass ejection at early times in the form of a neutrino-driven wind. Production of lanthanides and actinides saturates at short HMNS lifetimes (≲10 ms), with additional ejecta contributing to a blue optical kilonova component for longer-lived HMNSs. We find good agreement between the abundances from the disc outflow alone and the solar r-process distribution only for short HMNS lifetimes (≲10 ms). For longer lifetimes, the rare-earth and third r-process peaks are significantly underproduced compared to the solar pattern, requiring additional contributions from the dynamical ejecta. The nucleosynthesis signature from a spinning black hole (BH) can only overlap with that from an HMNS of moderate lifetime (≲60 ms). Finally, we show that angular momentum transport not only contributes with a late-time outflow component, but that it also enhances the neutrino-driven component by moving material to shallower regions of the gravitational potential, in addition to providing additional heating. | 161,808 |
title: Electronic Transport and Magnetic Properties in Y $_{0.125}$ Ca ${\rm }_{0.875}$ MnO $_{3}$ Manganite; abstract: A rare-earth-like manganite Y0.125Ca0.875MnO3 was systemically studied by the structure, electric and magnetic measurement. The results show that there exists a considerable magnetoresistance effect in this system. And two transitions are found on electrical transport corresponding to conventional metal-insulator (M-I) transition and Kondo-like behavior. From the magnetization in the zero-field-cooled (ZFC) and field-cooled (FC), a large irreversibility was observed with a cusp at 108 K about considered as spin-glass freezing temperature. Below 108 K, a coexistence of ferromagnetic spin-glass and ferromagnetic ordering phase appears, which indicates a long-range ferromagnetic behavior in spin-glass state. These suggest an intrinsic ferromagnetic spin-glass state in the Y0.125Ca0.875MnO3 system at low temperatures and may be suppressed with applied higher field of about 8.0 Tesla. | 161,809 |
title: Dielectric properties and electrical conductivity of neutron irradiated TGS single crystals; abstract: The dielectric constant, spontaneous polarization, the pyroelectric activity and the electrical conductivity were studied for TGS samples exposed to low doses of fast neutrons. The results obtained are discussed within the frame of the thermodynamic theory of ferroelectricity. An appreciable change was observed in the value of α (which is related to the Curie-Weiss Law) while a slight decrease was noted in β with increasing doses of radiation. The electrical conductivity was measured in the ferroelectric transition region. Radiation first increased the conductivity then decreased it. The observed anomaly disappeared either by irradiation or by application of an external poling field. The results are discussed taking into consideration lattice defects found. | 161,810 |
title: Approximating n-jet production; abstract: Abstract We present a simple approximation for the 6-gluon scattering amplitude which is accurate and can be rapidly evaluated on a computer. This should dramatically increase the statistics obtainable in Monte Carlo simulations of 4-jet production. We suggest that a similar approximation will hold for n -gluon scattering, n \u003e 6. | 161,811 |
title: An auto-locked diode laser system for precision metrology; abstract: We present a unique external cavity diode laser system that can be auto-locked with reference to atomic and molecular spectra. The vacuum-sealed laser head design uses an interchangeable base-plate comprised of a laser diode and optical elements that can be selected for desired wavelength ranges. The feedback light to the laser diode is provided by a narrow-band interference filter, which can be tuned from outside the laser cavity to fineadjust the output wavelength in vacuum. To stabilize the laser frequency, the digital laser controller relies either on a pattern-matching algorithm stored in memory, or on first or third derivative feedback. We have used the laser systems to perform spectroscopic studies in rubidium at 780 nm, and in iodine at 633 nm. The linewidth of the 780-nm laser system was measured to be ∼500 kHz, and we present Allan deviation measurements of the beat note and the lock stability. Furthermore, we show that the laser system can be the basis for a new class of lidar transmitters in which a temperature-stabilized fiber-Bragg grating is used to generate frequency references for on-line points of the transmitter. We show that the fiber-Bragg grating spectra can be calibrated with reference to atomic transitions. | 161,812 |
title: From electronic excited state theory to the property predictions of organic optoelectronic materials; abstract: We introduce here a work package for a National Natural Science Foundation of China Major Project. We propose to develop computational methodology starting from the theory of electronic excitation processes to predicting the opto-electronic property for organic materials, in close collaborations with experiments. Through developing methods for the electron dynamics, considering superexchange electronic couplings, spin-orbit coupling elements between excited states, electron-phonon relaxation, intermolecular Coulomb and exchange terms we combine the statistical physics approaches including dynamic Monte Carlo, Boltzmann transport equation and Boltzmann statistics to predict the macroscopic properties of opto-electronic materials such as light-emitting efficiency, charge mobility, and exciton diffusion length. Experimental synthesis and characterization of D-A type ambipolar transport material as well as novel carbon based material will provide a test ground for the verification of theory. | 161,813 |
title: X-ray observations of ultraluminous X-ray sources; abstract: Ultraluminous X-ray sources (ULXs) are amongst the most intriguing of X-ray source classes. Their extreme luminosities—greater than 1039 erg s−1 in the 0.3–10 keV band alone—suggest either the presence of black holes larger than those regularly encountered in our own Galaxy (the Galactic centre excepted), or sources apparently radiating well above the Eddington limit. We review the insights afforded us by studies of their X-ray emission, focussing on what this reveals about the underlying compact object. In particular, we discuss recent deep observations of ULXs by the XMM-Newton observatory, and how the unprecedented data quality provided by this mission is starting to discriminate between the different physical models for these extraordinary X-ray emitters. | 161,814 |
title: SUSY resonances from UHE neutralinos in neutrino telescopes and in the sky; abstract: In the Top-down scenarios, the decay of super-heavy particles (m ∼ 10 12−16 GeV), situated in dark-matter halos not very far from our Galaxy, can explain the ultra-high-energy (UHE) cosmic-ray spectrum beyond the Griesen-Zatasepin-Kuzmin cut-off. In case the dynamics of this decay is governed by the minimal supersymmetric standard model, a major component of the UHE cosmic-ray flux at PeV-EeV energies could be given by the lightest neutralino � 0 , that is the lightest stable supersymmetric particle. Then, the signal of UHE � 0 ’s on earth might emerge over the interactions of a comparable neutrino component. We compute the event rates for the resonant production of right selectrons (˜eR) and right squarks (˜qR) in mSUGRA, when UHE neutralinos of energy E� \u003e 10 5 GeV scatter off electrons and quarks in an earth-based detector like IceCube. When the resonant channel dominates in the total � 0 e,� 0 q scattering cross section, the only model parameters affecting the corresponding visible signal rates turn out to be the physical masses of the resonant right-scalar and of the lightest neutralino. We compare the expected number of supersymmetric events with the rates corresponding to the expected | 161,815 |
title: SECONDARY EMISSION FROM NON-SPHERICAL DUST GRAINS WITH ROUGH SURFACES: APPLICATION TO LUNAR DUST; abstract: Electrons impinging on a target can release secondary electrons and/or they can be scattered out of the target. It is well established that the number of escaping electrons per primary electron depends on the target composition and dimensions, the energy, and incidence angle of the primary electrons, but there are suggestions that the target\u0027s shape and surface roughness also influence the secondary emission. We present a further modification of the model of secondary electron emission from dust grains which is applied to non-spherical grains and grains with defined surface roughness. It is shown that the non-spherical grains give rise to a larger secondary electron yield, whereas the surface roughness leads to a decrease in the yield. Moreover, these effects can be distinguished: the shape effect is prominent for high primary energies, whereas the surface roughness predominantly affects the yield at the low-energy range. The calculations use the Lunar Highlands Type NU-LHT-2M simulant as a grain material and the results are compared with previously published laboratory and in situ measurements. | 161,816 |
title: Q-switched operation of a pulsed-laser-deposited Yb:Y 2 O 3 waveguide using graphene as a saturable absorber; abstract: The first, to the best of our knowledge, Q-switched operation of a pulsed-laser-deposited waveguide laser is presented. A clad Yb:Y2O3 waveguide was Q-switched using an output coupling mirror coated with a single layer of graphene deposited by atmospheric pressure chemical vapor deposition. During continuous-wave operation, a maximum power of 83 mW at a slope efficiency of 25% was obtained. During Q-switched operation, pulses as short as 98 ns were obtained at a repetition rate of 1.04 MHz and a central wavelength of 1030.8 nm. | 161,817 |
title: Axion — Dilaton Coupling and Gamma — Ray Bursts; abstract: Axions emitted in supernovae are interesting candidates to account for Gamma-Ray Bursts provided their energy can be effectively converted into electromagnetic energy elsewhere. We point out that this convertion may occur more efficiently if one considers the coupling between intermediate scale axions and the string theory dilaton along with the inclusion of string loops. | 161,818 |
title: New evaluation of muon (g − 2) hadronic anomaly☆; abstract: Abstract The hadronic part a H of the muon g -factor anomaly a ≡ (g − 2) 2 is evaluated from latest data on σ (e + e − → hadrons). For a p-wave ππ scattering length of a 1 = 0.04±0.005 we calculate a H = (66±10) × 10 −9 , compared to a (experiment) − a (QED) = (60±29) × 10 −9 . Half of the uncertainty on a H is associated with the energy interval 0.92 s GeV . | 161,819 |
title: On wavy instabilities of the Taylor-vortex flow between corotating cylinders; abstract: At least four wavy instabilities are found numerically by analysing the linear stability of Taylor-vortex flow (TVF) in the limit of a small gap between two concentric cylinders which rotate differentially in the same direction. Two of the wavy instabilities, including the one leading to conventional wavy vortex (WVF), have the same axial wavelength as TVF at the onset of instability, while the other two are characterized by subharmonic modes with axial wavelengths twice as long as those of TVF. The two subharmonic instabilities appear to correspond to the wavy-inflow-boundary flow (WIB) and the wavy-outflow-boundary flow (WOB) observed in the experiment of Andereck, Liu \u0026 Swinney (1986). The phase velocities, measured in the rotating frame of reference, of all the wavy instabilities are non-zero at the onset except that the phase velocity of WVF vanishes in the region where the average rotation rate Ω of the cylinders is small. By using this simple bifurcation property of WVF for small Ω, time-independent finite-amplitude non-axisymmetric solution branches bifurcating from TVF are followed numerically. The most interesting findings are that some of the solution branches cross the line Ω = 0, producing three-dimensional nonlinear solutions in plane Couette flow. | 161,820 |
title: The 2.5 m Telescope of the Sloan Digital Sky Survey; abstract: We describe the design, construction, and performance of the Sloan Digital Sky Survey telescope located at Apache Point Observatory. The telescope is a modified two-corrector Ritchey-Chretien design with a 2.5 m, f/2.25 primary, a 1.08 m secondary, a Gascoigne astigmatism corrector, and one of a pair of interchangeable highly aspheric correctors near the focal plane, one for imaging and the other for spectroscopy. The final focal ratio is f/5. The telescope is instrumented by a wide-area, multiband CCD camera and a pair of fiber-fed double spectrographs. Novel features of the telescope include the following: (1) A 3° diameter (0.65 m) focal plane that has excellent image quality and small geometric distortions over a wide wavelength range (3000-10,600 A) in the imaging mode, and good image quality combined with very small lateral and longitudinal color errors in the spectroscopic mode. The unusual requirement of very low distortion is set by the demands of time-delay-and-integrate (TDI) imaging. (2) Very high precision motion to support open-loop TDI observations. (3) A unique wind baffle/enclosure construction to maximize image quality and minimize construction costs. The telescope had first light in 1998 May and began regular survey operations in 2000. | 161,821 |
title: Luminosity dependent star-formation history of S0 galaxies: evidence from GALEX-SDSS-2MASS-WISE colours; abstract: We combine UV/Optical/near-IR/mid-IR data on a sample of ~240 S0 galaxies to examine various star formation related processes in them. We split the sample into bright and faint S0 galaxies based on their K band luminosity. Comparing the FUV-NUV versus NUV-K color-color diagram with a Simple Stellar Population (SSP) model shows that ellipticals and bright S0 galaxies are dominated by a stellar population of age \u003e 10^9 years while faint S0 galaxies may contain stars as young as 10^8 years, providing evidence for relatively recent star formation activity. The strength of the 4000A break is also systematically higher in brighter S0 galaxies, again indicating the presence of an old stellar population. Their mid-IR colours indicate that bright S0 colours are like those of ellipticals while faint S0 colours are more like spirals. All these observations are consistent with a scenario in which low-luminosity S0 galaxies likely formed by the stripping of gas from the discs of late-type spiral galaxies, which in turn formed their pseudo bulges through secular evolution processes, possibly involving multiple episodes of star formation. On the other hand, more luminous S0 galaxies likely formed the bulk of their stars at early epochs, similar to the star formation in elliptical galaxies, and are characterised by an old coeval stellar population and classical bulge | 161,822 |
title: The electric dipole moment of the tau; abstract: Abstract Although stringent limits exist on the electric dipole moments of the neutron, electron and muon, there is very little information on the electric dipole moment of the tau. Such a dipole moment would be observable in the angular distribution of the tau pairs in electron-position annihilation. We calculate the effects of an electric dipole moment on this angular distribution, and show that the current upper bound on the electric dipole moment is 1.4 × 1016 e cm. This bound could be improved significantly at a tau factory. The electric dipole moment of neutrinos is also discussed. | 161,823 |
title: Colloquium: Random matrices and chaos in nuclear spectra; abstract: Chaos occurs in quantum systems if the statistical properties of the eigenvalue spectrum coincide with predictions of random-matrix theory. Chaos is a typical feature of atomic nuclei and other self-bound Fermi systems. How can the existence of chaos be reconciled with the known dynamical features of spherical nuclei? Such nuclei are described by the shell model (a mean-field theory) plus a residual interaction. The question is answered using a statistical approach (the two-body random ensemble): The matrix elements of the residual interaction are taken to be random variables. Chaos is shown to be a generic feature of the ensemble and some of its properties are displayed, emphasizing those which differ from standard random-matrix theory. In particular, the existence of correlations among spectra carrying different quantum numbers is demonstrated. These are subject to experimental verification. | 161,824 |
title: New data acquisition system for the RIKEN Radioactive Isotope Beam Factory; abstract: A new data-acquisition (DAQ) system has been introduced at the RIKEN Radioactive Isotope Beam Factory (RIBF). This system has functions of network-distributed data processing, hierarchical event building and parallel readout which are achieved with newly developed software and commodity hardware. This system is both versatile and scalable, allowing it to meet the various requirements for RIBF experiments. It has a maximum data processing capability of around 40 MB/s. This paper describes the configuration and the data processing performance of the DAQ system. | 161,825 |
title: No static black hole hairs in gravitational theories with broken Lorentz invariance; abstract: In this paper, we revisit the issue of static hairs of black holes in gravitational theories with broken Lorentz invariance in the case that the speed $c_{\\phi}$ of the khronon field becomes infinitely large, $c_{\\phi} = \\infty$, for which the sound horizon of the khronon field coincides with the universal horizon, and the boundary conditions at the sound horizon reduce to those given normally at the universal horizons. As a result, less boundary conditions are present in this extreme case in comparison with the case $c_{\\phi} = $ finite. Then, it would be expected that static hairs might exist. However, we show analytically that even in this case static hairs still cannot exist, based on a decoupling limit analysis. We also consider the cases in which $c_{\\phi}$ is finite but with $c_{\\phi} \\gg 1$, and obtain the same conclusion. | 161,826 |
title: The High Time Resolution Universe Pulsar Survey - XIII. PSR J1757-1854, the most accelerated binary pulsar; abstract: We report the discovery of PSR J1757$-$1854, a 21.5-ms pulsar in a highly-eccentric, 4.4-h orbit around a neutron star (NS) companion. PSR J1757$-$1854 exhibits some of the most extreme relativistic parameters of any known pulsar, including the strongest relativistic effects due to gravitational-wave (GW) damping, with a merger time of 76 Myr. Following a 1.6-yr timing campaign, we have measured five post-Keplerian (PK) parameters, yielding the two component masses ($m_\\text{p}=1.3384(9)\\,\\text{M}_\\odot$ and $m_\\text{c}=1.3946(9)\\,\\text{M}_\\odot$) plus three tests of general relativity (GR), which the theory passes. The larger mass of the NS companion provides important clues regarding the binary formation of PSR J1757$-$1854. With simulations suggesting 3-$\\sigma$ measurements of both the contribution of Lense-Thirring precession to the rate of change of the semi-major axis and the relativistic deformation of the orbit within $\\sim7-9$ years, PSR J1757$-$1854 stands out as a unique laboratory for new tests of gravitational theories. | 161,827 |
title: Low-energy constraints on new physics reexamined; abstract: It is possible to place constraints on non-standard-model gauge-boson self-couplings and other new physics by studying their one-loop contributions to precisely measured observables. We extend previous analyses which constrain such nonstandard couplings, and we present the results in a compact and transparent form. Particular attention is given to comparing results for the light-Higgs scenario, where nonstandard effects are parametrized by an effective Lagrangian with a linear realization of the electroweak symmetry-breaking sector, and the heavy-Higgs or strongly interacting scenario, described by the electroweak chiral Lagrangian. The constraints on nonstandard gauge-boson self-couplings which are obtained from a global analysis of low-energy data and CERN LEP or SLC measurements on the $Z$ pole are updated and improved from previous studies. | 161,828 |
title: Semi-analytic derivation of the threshold mass for prompt collapse in binary neutron-star mergers; abstract: The threshold mass for prompt collapse in binary neutron-star (NS) mergers was empirically found to depend on the stellar properties of the maximum-mass non-rotating NS model. Here, we present a semi-analytic derivation of this empirical relation, which suggests that it is rather insensitive to thermal effects, to deviations from axisymmetry and to the exact rotation law in merger remnants. We utilize axisymmetric, cold equilibrium models with differential rotation and determine the threshold mass for collapse from the comparison between an empirical relation that describes the angular momentum in the remnant for a given total binary mass and the sequence of rotating equilibrium models at the threshold to collapse (the latter assumed to be near the turning point of fixed-angular-momentum sequences). In spite of the various simplifying assumptions, the empirical relation for prompt collapse is reproduced with good accuracy, which demonstrates its robustness. We discuss implications of our methodology and results for understanding other empirical relations satisfied by NS merger remnants that have been discovered by numerical simulations and that play a key role in constraining the high-density equation of state through gravitational-wave observations. | 161,829 |
title: Mode Conversion in Acoustically Modulated Confined Jets; abstract: This paper is concerned with the response of confined low-Reynolds-number jets to external modulations of large amplitudes. The jet formed inside a duct by an orifice plate is submitted to flow perturbations impinging on the constriction from the upstream side. Vortices are generated in the downstream region, giving rise to conversion from acoustic oscillation to convective modes. Experiments and simulations are carried out to characterize this important mode conversion process. It is shown that the convective perturbation phase is a linear function of the distance from the orifice plate and of the operating frequency. Data can be collapsed into a single curve with some scatter providing a scaling rule for the phase. Numerical simulations are carried out and a method is developed to decompose the local velocity perturbations into acoustic and convective components. This is used to determine the amplitudes of upstream and downstream acoustic velocities and of the convective perturbations on the downstream side of the orifice. It is shown that the acoustic velocity approximated by a bulk oscillation in the orifice vicinity is reduced at the constriction and that this is simultaneously compensated by the generation of convective perturbations. The conversion efficiency of this process is characterized. Results obtained can be used to design flow control devices; they provide insight into the generation of vortices in orifice plate systems submitted to large pressure oscillations and could be useful to the analysis of vortex instabilities in segmented solid rocket engines. | 161,830 |
title: SOLUBILITY OF WATER ICE IN METALLIC HYDROGEN: CONSEQUENCES FOR CORE EROSION IN GAS GIANT PLANETS; abstract: Using ab initio simulations we investigate whether water ice is stable in the cores of giant planets, or whether it dissolves into the layer of metallic hydrogen above. By Gibbs free energy calculations we find that for pressures between 10 and 40 Mbar the ice-hydrogen interface is thermodynamically unstable at temperatures above approximately 3000 K, far below the temperature of the core-mantle boundaries in Jupiter and Saturn. This implies that the dissolution of core material into the fluid layers of giant planets is thermodynamically favored, and that further modeling of the extent of core erosion is warranted. | 161,831 |
title: Nuclei and the Unitary Limit; abstract: Few-body systems with large scattering length display universal properties which are independent of the details of short-distance dynamics. These features include universal correlations between few-body observables and a geometric spectrum of three- and higher-body bound states. They can be observed in a wide range of systems from ultracold atoms to hadrons and nuclei. In this contribution, we review universality in nuclei dominated by few-body physics. In particular, we discuss halo nuclei and the description of light nuclei in a strict expansion around the unitary limit of infinite scattering length. | 161,832 |
title: Diagnostics of timing noise in middle-aged pulsars; abstract: Radio pulsars are often used as clocks in a wide variety of experiments. Imperfections in the clock, known as timing noise, have the potential to reduce the significance of, or even thwart e.g. the attempt to find a stochastic gravitational wave (GW) background. We measure the timing noise in a group of 129 mostly middle-aged pulsars (i.e. characterstic ages near 1~Myr) observed with the Parkes radio telescope on a monthly basis since 2014. We examine four different metrics for timing noise, but it remains unclear which, if any, provides the best determination. In spite of this, it is evident that these pulsars have significantly less timing noise than their younger counterparts, but significantly more than the (much older) millisecond pulsars (MSPs). As with previous authors, we find a strong correlation between timing noise and the pulsar spin-down rate, $\\dot{\\nu}$. However, for a given $\\dot{\\nu}$ there is a spread of about a factor 30 in the strength of the timing noise likely indicating that nuclear conditions in the interior of the stars differs between objects. We briefly comment on the implications for GW detection through pulsar timing arrays as the level of timing noise in MSPs may be less than predicted. | 161,833 |
title: Polarization behavior during high field poling of poly(vinylidene fluoride); abstract: The polarization process which takes place during electric poling of poly(vinylidene fluoride) is investigated by measuring the time dependence of currents in poling circuits with varying RC time constants. For applied voltages between 3 and 8 kV (average field strengths 1.2–3.2 MV/cm) and RC values between 10 and 10−3 s, the current‐time behavior, normalized by the corresponding RC time constants and initial current values, can be described by a single curve (quasi‐steady state). Such a representation indicates that the switching of polarization is simply a voltage‐ or field‐induced effect. A phenomenological description of the poling process is presented which allows one to determine the dependence of polarization with respect to the voltage across the sample. The corresponding density function shows a steep rise in polarization at about 2400 V (average electric field strength 1 MV/cm) followed by an exponentially decaying tail toward higher voltages. Implication of such a distribution is discussed briefly. | 161,834 |
title: The tau weak-magnetic dipole moment; abstract: Abstract We calculate the prediction for the anomalous weak-magnetic form factor of the tau lepton at q 2 = M 2 within the Standard Model. With all particles on-shell, this is an electroweak gauge-invariant quantity. Its value is a τ w ( M Z 2 )= − (2.10+0.61 i ) × 10 −6 . We show that the transverse and normal components of the single-tau polarization of tau pairs produced at e + e − unpolarized collisions are sensitive to the real and absorptive parts of the anomalous weak-magnetic dipole moment of the tau. The sensitivity one can achieve at LEP in the measurement of this dipole moment is discussed. | 161,835 |
title: Dynamic interactions of multiple wall-mounted flexible flaps; abstract: Coherent waving interactions between vegetation and fluid flows are known to emerge under conditions associated with the mixing layer instability. A similar waving motion has also been observed in flow control applications, where passive slender structures are used to augment bluff body wakes. While their existence is well reported, the mechanisms which govern this behaviour, and their dependence on structural properties, are not yet fully understood. This work investigates the coupled interactions of a large array of slender structures in an open-channel flow, via numerical simulation. A direct modelling approach, whereby the individual structures are fully resolved, is realised via a lattice Boltzmann-immersed boundary-finite element model. For steady flow conditions at low–moderate Reynolds number, the response of the array is measured over a range of mass ratio and bending rigidity, spanning two orders of magnitude, and the ensuing response is characterised. The results show a range of behaviours which are classified into distinct states: static, regular waving, irregular waving and flapping. The regular waving regime is found to occur when the natural frequency of the array approaches the estimated frequency of the mixing layer instability. Furthermore, after normalising with respect to the natural frequency of the array, the frequency response across the examined parameter space collapses onto a single curve. These findings indicate that the coherent waving mode is in fact a coupled instability, as opposed to a purely fluid-driven response, and that this specific regime is triggered by a lock-in between the fluid and structural natural frequencies. | 161,836 |
title: PARAMETRIC RELATIONS FOR THE ATMOSPHERIC BOUNDARY LAYER; abstract: Some parametric relations for the atmospheric planetary boundary layer (PBL) are suggested for possible use in the various atmospheric circulation and air quality models, as well as in other applications. These are for parameterizing the mean wind and temperature profiles, the vertical fluxes of momentum, heat and moisture, the variances of velocity fluctuations and length and time scales in the PBL. The parametric relations for the PBL height, the vertical velocity at the top of the PBL and the total energy dissipation in the PBL are also discussed. Experimental and/or theoretical bases for the various parametric relation are given. Some of the suggested parameterizations should be considered as tentative, until they are properly validated. | 161,837 |
title: Axisymmetric flows in spin-up from rest of a stratified fluid in a cylinder; abstract: Abstract Numerical solutions of the axisymmetric flows during the relatively early phase of spin-up from rest of a stratified fluid in a cylinder are presented. Detailed results are given for a cylinder of aspect ratio of O(l) and for a minute Ekman number, showing axisymmetric spin-up for three values of the stratification parameter. As the stratification increases, the meridional circulation is confined to a region closer to the Ekman layers. An axisymmetric shear wave propagates radially inward from the sidewall, but, unlike the strictly vertical front for a homogeneous fluid, the interface which separates rotating from nonrotating fluid is bow-shaped. For a stratified fluid, the axial vorticity distribution is nonuniform both in the vertical and in the radial directions. With increasing stratification, diffusive vorticity production near the sidewall is more pronounced. Axisymmetric flows in the early phase of spin-up of a stratified fluid are controlled by both the inviscid dynamic effect and the vis... | 161,838 |
title: Continuum Tamm-Dancoff-Approximation calculations of the escape widths of the Gamow-Teller resonance in 208Bi; abstract: Abstract The proton escape widths of the Gamow-Teller resonance and the isobaric analog state in 208 Bi are calculated by solving the charge-exchange continuum Tamm-Dancoff equations. For the Gamow-Teller resonance the spreading contribution to the width is taken into account by the imaginary part of the optical potential. The calculated escape widths are in agreement with measurements obtained from a recent 208 Pb ( 3 He ,tp) 208 Bi experiment. | 161,839 |
title: Enhancement in magnetoelectric response in CoFe2O4–BaTiO3 heterostructure; abstract: CoFe2O4–BaTiO3 heterostructure was epitaxially grown on the (001)-SrTiO3 substrate via pulsed laser deposition, in which the bottom BaTiO3 layer epitaxially grown on the substrate acts as a buffer layer and effectively reduces the coherent constraint in the magnetic layer arising from the substrate. Microstructure studies from x-ray diffraction and electron microscopies showed good coherent epitaxy thin films of the (001)-CoFe2O4 and (001)-BaTiO3 on the substrate, which exhibits simultaneously strong ferroelectric and ferromagnetic responses. An obvious direct magnetoelectric coupling effect was observed in the thin films, which shows an enhancement compared to previous NiFe2O4–BaTiO3 heterostructures. | 161,840 |
title: Correlation potential method for the calculation of energy levels, hyperfine structure and E1 transition amplitudes in atoms with one unpaired electron; abstract: Energy levels, fine and hyperfine structure, as well as E1 transition amplitudes in thallium and gold, are calculated. Application of the relativistic Hartree-Fock equations, taking into account electron shell polarisation and correlation corrections to the wavefunction, provides an accuracy of the order of a few per cent as a rule. This is an order of magnitude better than the accuracy of simple Hartree-Fock calculations. An estimate for structural radiation is made. | 161,841 |
title: The globular cluster system of NGC 4374; abstract: We study the globular cluster system (GCS) of the giant elliptical NGC 4374 (M 84) in the Virgo cluster using B and R photometry. The colour distribution is bimodal with peaks at $B-R=1.11$ and $B-R=1.36$, fitting well to those found in other early-type galaxies. The radial profile of the cluster number density is flatter than the galaxy light. Using the luminosity function we derive a distance modulus of $\\mu=31.61\\pm0.2$, which within the uncertainty agrees with the distance from surface brightness fluctuations. Blue and red clusters show similar radial concentrations and azimuthal distributions. The total number of clusters is $N=1775\\pm150$, which together with our distance modulus leads to a specific frequency of $S_{N}=1.6\\pm0.3$. This value is surprisingly low for a giant elliptical, but resembles the case of merger remnants like NGC 1316, where the low specific frequency is probably caused by the luminosity contribution of an intermediate-age population. A further common property is the high rate of type Ia supernovae which also may indicate the existence of a younger population. However, unlike in the case of NGC 1316, one cannot find any further evidence that NGC 4374 indeed hosts younger populations. The low specific frequency would also fit to a S0 galaxy seen face-on. | 161,842 |
title: Radiance and Doppler shift distributions across the network of the quiet Sun; abstract: Aims. The radiance and Doppler-shift distributions across the solar network provide observational constraints of two-dimensional modeling of transition-region emission and flows in coronal funnels. These distributions have not, however, been studied in detail and we attempt an investigation for a quiet Sun region. Methods. Two different methods, dispersion plots and average-profile studies, were applied to investigate these distributions for three EUV lines. In the dispersion plots, we divided the entire quiet Sun region scanned by SUMER into a bright and a dark part according to an image of Fe xii taken by EIT during the scanning; we plotted intensities and Doppler shifts in each bin as determined according to a filtered intensity of Si ii. We also studied the difference in height variations of the magnetic field as extrapolated from the MDI magnetogram, in and outside network, in the two parts. For the average-profile study, we selected 74 individual cases and derived the average profiles of intensities and Doppler shifts across the network. Cases with large values of blue shift of Ne viii were further studied. Results. The dispersion plots reveal that the intensities of Si ii and C iv increase from network boundary to network center in both the bright and dark parts. However, the intensity of Ne viii shows different trends, namely increasing in the bright part and decreasing in the dark part. In both parts, the Doppler shift of C iv increases steadily from internetwork to network center. The height variations in the magnetic field imply a more homogeneous magnetic structure at greater heights and clearly reflect the different magnetic structures in the two regions. The average-profile study reveals that the intensities of the three lines all decline from the network center to internetwork region. The binned intensities of Si ii and Ne viii have a good correlation. We also find that the large blue shift of Ne viii does not coincide with large red shift of C iv. Conclusions. Our results suggest that the network structure is still prominent at the layer where Ne viii is formed in the quiet Sun, and that the magnetic structures expand more strongly in the dark part than in the bright part of this quiet Sun region. Our results might also hint for a scenario of magnetic reconnection between open funnels and side loops. | 161,843 |
title: Measurements of the mechanical Q of single-crystal silicon at low temperatures; abstract: Measurements of the mechanical quality factor Q in a single crystal of silicon vs. temperature have been made. A value of 2 × 109 has been measured at T = 3.5K. | 161,844 |
title: On anthropic solutions of the cosmological constant problem; abstract: Motivated by recent work of Bousso and Polchinski (BP), we study theories which explain the small value of the cosmological constant using the anthropic principle. We argue that simultaneous solution of the gauge hierarchy problem is a strong constraint on any such theory. We exhibit three classes of models which satisfy these constraints. The first is a version of the BP model with precisely two large dimensions. The second involves 6-branes and antibranes wrapped on supersymmetric 3-cycles of Calabi-Yau manifolds, and the third is a version of the irrational axion model. All of them have possible problems in explaining the size of microwave background fluctuations. We also find that most models of this type predict that all constants in the low energy lagrangian, as well as the gauge groups and representation content, are chosen from an ensemble and cannot be uniquely determined from the fundamental theory. In our opinion, this significantly reduces the appeal of this kind of solution of the cosmological constant problem. On the other hand, we argue that the vacuum selection problem of string theory might plausibly have an anthropic, cosmological solution. | 161,845 |
title: Influence of internal viscosity on the large deformation and buckling of a spherical capsule in a simple shear flow; abstract: The motion and deformation of a spherical elastic capsule freely suspended in a simple shear flow is studied numerically, focusing on the effect of the internal-to-external viscosity ratio. The three-dimensional fluid–structure interactions are modelled coupling a boundary integral method (for the internal and external fluid motion) with a finite element method (for the membrane deformation). For low viscosity ratios, the internal viscosity affect the capsule deformation. Conversely, for large viscosity ratios, the slowing effect of the internal motion lowers the overall capsule deformation; the deformation is asymptotically independent of the flow strength and membrane behaviour. An important result is that increasing the internal viscosity leads to membrane compression and possibly buckling. Above a critical value of the viscosity ratio, compression zones are found on the capsule membrane for all flow strengths. This shows that very viscous capsules tend to buckle easily. | 161,846 |
title: A Generalized Canonical Formalism and Quantization of Reducible Gauge Theories; abstract: Abstract A general solution for the S -matrix of relativistic dynamical systems subject to Bose and Fermi first and second class constraints is obtained by canonical quantization in the case of reducibility, i.e. when the first class constraints are linearly dependent. The null-eigenvectors of the constraints may also be linearly dependent and possess null-eigenvectors of their own, which, in their turn, may be linearly dependent, etc. The solution obtained remains valid in the present case of multistage reducibility of constraints. | 161,847 |
title: A balanced-force control volume finite element method for interfacial flows with surface tension using adaptive anisotropic unstructured meshes; abstract: A balanced-force control volume finite element method is presented for three-dimensional interfacial flows with surface tension on adaptive anisotropic unstructured meshes. A new balanced-force algorithm for the continuum surface tension model on unstructured meshes is proposed within an interface capturing framework based on the volume of fluid method, which ensures that the surface tension force and the resulting pressure gradient are exactly balanced. Two approaches are developed for accurate curvature approximation based on the volume fraction on unstructured meshes. The numerical framework also features an anisotropic adaptive mesh algorithm, which can modify unstructured meshes to better represent the underlying physics of interfacial problems and reduce computational effort without sacrificing accuracy. The numerical framework is validated with several benchmark problems for interface advection, surface tension test for equilibrium droplet, and dynamic fluid flow problems (fluid films, bubbles and droplets) in two and three dimensions. | 161,848 |
title: Precise Stellar Radial Velocities of an M Dwarf with a Michelson Interferometer and a Medium-resolution Near-infrared Spectrograph; abstract: Precise near-infrared radial velocimetry enables efficient detection and transit verification of low-mass extrasolar planets orbiting M dwarf hosts, which are faint for visible-wavelength radial velocity surveys. The TripleSpec Exoplanet Discovery Instrument, or TEDI, is the combination of a variable-delay Michelson interferometer and a medium-resolution (R=2700) near-infrared spectrograph on the Palomar 200\" Hale Telescope. We used TEDI to monitor GJ 699, a nearby mid-M dwarf, over 11 nights spread across 3 months. Analysis of 106 independent observations reveals a root-mean-square precision of less than 37 m/s for 5 minutes of integration time. This performance is within a factor of 2 of our expected photon-limited precision. We further decompose the residuals into a 33 m/s white noise component, and a 15 m/s systematic noise component, which we identify as likely due to contamination by telluric absorption lines. With further development this technique holds promise for broad implementation on medium-resolution near-infrared spectrographs to search for low-mass exoplanets orbiting M dwarfs, and to verify low-mass transit candidates. | 161,849 |
title: The phase diagrams and the magnetic properties of a ternary mixed ferrimagnetic nanowire; abstract: Abstract A hexagonal nanowire consisting of a ferromagnetic spin- 1 2 core, spin-1 inter core/shell and spin- 3 2 outer shell coupled with ferrimagnetic interlayer couplings has been studied by the use of Monte Carlo simulation based on the heat bath algorithm. The exchange interactions and the uniaxial anisotropy effects on the magnetic properties of the system have been discussed. We found that, the system exhibits the compensation phenomenon, the first and the second order transitions. Moreover, we have obtained that, the existence of the tricritical point depend on the surface shell interaction. | 161,850 |
title: Calculation of the second-order goldstone diagram in nuclear matter☆; abstract: A comparison is made of various methods used to calculate the second-order energy in nuclear matter. A general expression is derived for integrands depending only on k2,k′2 and k·k′, wherekandk′ are relative momenta. It applies to any potential, local or nonlocal, which can be expanded in partial waves of the relative motion, and this allows the exchange term to be combined with the direct term. Because of the short range of the nuclear force, only a few terms in the partial wave expansion are necessary. The number of integrations that need to be performed numerically for each new potential is reduced to two. Special formulas are presented for central, tensor, spin-orbit, and velocity-dependent forces. | 161,851 |
title: Laser-Doppler measurements of turbulent-flow parameters in a stirred mixer; abstract: It is recognized that a detailed knowledge of turbulence parameters, as well as velocities, can aid in understanding and modelling mixing rate dominated phenomena in stirred vessels. Turbulent-flow parameters were measured in a baffled, Rushton turbine agitated vessel with a laser-Doppler velocimeter. The necessary corrections for the periodic, nondissipative velocity fluctuations in the near impeller region were made by an autocorrelation method. Two components of periodic fluctuation, one corresponding to impeller blade frequency, the other corresponding to twice that frequency, were found to be significant. With the periodicity removed, meaningful turbulence intensities, autocorrelation functions, turbulence scales, energy spectra, and turbulence energy dissipation reates were obtained. Integral scales and turbulence energy dissipation rates were a particular objective in this work because of their usefulness in modelling local mixing rates in turbulence flows. From an energy balance around the impeller and impeller stream, it was found that 60% of the energy transmitted into the tank via impeller was dissipated in that region, and 40% was dissipated in the bulk of the tank. An equation for calculating local energy dissipation rates from resultant fluctuation velocities and resultant turbulence macroscales, , appeared adequate. Constant A was found to be 0.85. | 161,852 |
title: Linear and nonlinear analysis of shallow wakes; abstract: The bottom friction and the limited vertical extent of the water depth play a significant role in the dynamics of shallow wakes. These effects along with the effect of the strength of the shear layer define the wake parameter S. A nonlinear model, based on a second-order explicit finite volume solution of the depth-averaged shallow water equation in which the fluxes are obtained from the solution of the Bhatnagar–Gross– Krook (BGK) Boltzmann equation, is developed and applied to shallow wake flows for which laboratory data are available. The velocity profiles, size of the recirculating wake, oscillation frequency, and wake centreline velocity are studied. The computed and measured results are in reasonable agreement for the vortex street (VS) and unsteady bubble (UB) regimes, but not for the steady bubble (SB). The computed length of the recirculation region is about 60 % shorter than the measured value when S belongs to the SB regime. As a result, the stability investigation performed in this paper is restricted to S values away from the transition between SB and UB. Linear analysis of the VS time-averaged velocity profiles reveals a region of absolute instability in the vicinity of the cylinder associated with large velocity deficit, followed by a region of convective instability, which is in turn followed by a stable region. The frequency obtained from Koch’s criterion is in good agreement with the shedding frequency of the fully developed VS. However, this analysis does not reveal the mechanism that sets the global shedding frequency of the VS regime because the basic state is obtained from the VS regime itself. The mechanism responsible for VS shedding is sought by investigating the stability behaviour of velocity profiles in the UB regime as S is decreased towards the critical value which defines the transition from the UB to the VS. The results show that the near wake consists of a region of absolute instability sandwiched between two convectively unstable regions. The frequency of the VS appears to be predicted well by the selection criteria given in Pier \u0026 Huerre (2001) and Pier (2002), suggesting that the ‘wave-maker’ mechanism proposed in Pier \u0026 Huerre (2001) in the context of deep wakes remains valid for shallow wakes. The amplitude spectra produced by the nonlinear model are characterized by a narrow band of large-amplitude frequencies and a wide band of small-amplitude frequencies. Weakly nonlinear analysis indicates that the small amplitude frequencies are due to secondary instabilities. Both the UB and VS regimes are found to be insensitive to random forcing at the inflow boundary. The insensitivity to random noise is consistent with the linear results which show that the UB and VS flows contain regions of absolute instabilities in the near wake where the velocity deficit is large. | 161,853 |
title: Exchange interactions and magnetocaloric effects of the Heusler alloys Ni–Mn–In–R (R = Fe, Co); abstract: The magnetic interactions and magnetocaloric effects in Ni2Mn1.4In0.6−xRx (x = 0–0.2) (R = Fe, Co) Heusler alloys are investigated by the first-principles and Monte Carlo method. The ab initio calc... | 161,854 |
title: Effects of the 17 keV neutrino in supernovae; abstract: Abstract We discuss the astrophysical implications of the 17 keV neutrino, recently discovered in beta decay experiments. We show that due to their large mixing with the electron neutrinos enhanced by the matter effect, the 17 keV neutrinos are copiously produced in the core of supernovae. This may have substantial effects on the dynamics of the collapse. We consider alternative interpretations of the 17 keV neutrino and give a qualitative discussion on their consequences on the physics of supernovae. | 161,855 |
title: Three-dimensional X-ray micro-velocimetry.; abstract: A direct measurement of three-dimensional X-ray velocimetry with micrometer spatial resolution is presented. The key to this development is the use of a Laue crystal as an X-ray beam splitter and mirror. Three-dimensional flow velocities in a 0.4 mm-diameter tubing were recorded, with \u003c5 µm spatial resolution and speeds of 0.7 mm s−1. This development paves the way for three-dimensional velocimetry in many cases where visible-light techniques are not effective, such as multiphase flow or flow of optically opaque liquids. | 161,856 |
title: Newtonian View of General Relativistic Stars; abstract: Although general relativistic cosmological solutions, even in the presence of pressure, can be mimicked by using neo-Newtonian hydrodynamics, it is not clear whether there exists the same Newtonian correspondence for spherical static configurations. General relativity solutions for stars are known as the Tolman-Oppenheimer-Volkoff (TOV) equations. On the other hand, the Newtonian description does not take into account the total pressure effects and therefore can not be used in strong field regimes. We discuss how to incorporate pressure in the stellar equilibrium equations within the neo-Newtonian framework. We compare the Newtonian, neo-Newtonian and the full relativistic theory by solving the equilibrium equations for both three approaches and calculating the mass-radius diagrams for some simple neutron stars equation of state. | 161,857 |
title: Semiconducting properties of magnesium vanadate glasses; abstract: The electrical conductivity of semiconducting magnesium vanadate glasses has been reported for a wide composition range in the temperature range of 80–500 K. The experimental results have been analyzed in the framework of different hopping models. It has been observed that the multiphonon assisted hopping model of small polarons in the nonadiabatic regime, proposed by Emin, can interpret the temperature dependence of the conductivity data of these glasses over the entire temperature range of measurement. The parameters obtained from the fits of the experimental data to this model appear reasonable and are consistent with the glass composition. On the other hand, Mott’s optical phonon assisted hopping model at high temperatures provides smaller values of the localization length. However, Mott’s variable range hopping model is consistent with the low temperature data. Schnakenberg’s model yields higher values of the hopping and the disorder energies than the activation energy obtained at the highest and the lowest temperature ranges. | 161,858 |
title: Fully Developed Turbulence and the Multifractal Conjecture; abstract: We review the Parisi-Frisch (Proc. Int. School of Physics “E. Fermi”, pp. 84–87, North-Holland, Amsterdam, 1985) MultiFractal formalism for Navier-Stokes turbulence with particular emphasis on the issue of statistical fluctuations of the dissipative scale. We do it for both Eulerian and Lagrangian Turbulence. We also show new results concerning the application of the formalism to the case of Shell Models for turbulence. The latter case will allow us to discuss the issue of Reynolds number dependence and the role played by vorticity and vortex filaments in real turbulent flows. | 161,859 |
title: Stability of buoyancy and surface tension driven convection in a horizontal double-diffusive fluid layer; abstract: Abstract Linear stability analysis has been applied to examine the stability of convection in a horizontal double-diffusive fluid layer driven by the combined effects of buoyancy and surface tension. Such a convective flow may serve as an idealized model of the horizontal Bridgman process for crystallization or solidification of liquid melts. Results show that salt-finger instability is excited over a wide range of thermal and solutal Grashof numbers. Travelling wave instabilities caused by surface tension effects are excited when the effective Marangoni number becomes large. | 161,860 |
title: Influence of Fe doped manganite on critical behavior of La0.6Nd0.1(Ca,Sr)0.3Mn1−xFexO3; abstract: Abstract The samples of manganese perovskite La 0.6 Nd 0.1 (Sr,Ca) 0.3 Mn 1− x Fe x O 3 ( x =0.0, 0.05 and 0.1) were prepared by a solid–solid method and all of them achieved an orthorhombic perovskite structure, revealed by X-ray diffraction. Investigations into temperature and magnetic-field dependences of magnetization indicated a gradual decrease of the ferromagnetic–paramagnetic transition temperature ( T C ) from 326 to 296 K with increasing Fe-doping. The experimental results revealed that all the samples were undergone a second-order phase transition. The critical properties near ferromagnetic–paramagnetic phase transition temperature have been analyzed from data of static magnetization measurements for the samples, using various techniques such as a modified Arrott plot (MAP), Kouvel–Fisher (KF) method and critical isotherm (CI) analysis. Critical exponents for x =0.0 and x =0.05 samples are close to the theoretical prediction from the 3D-Heisenberg and for x =0.1sample the values obtained for the critical exponents are close to those predicted by the tri-critical mean-field. | 161,861 |
title: A study of strange particle production in νμ charged current interactions in the NOMAD experiment; abstract: A study of strange particle production in $\\nu_\\mu$ charged current interactions has been performed using the data from the NOMAD experiment. Yields of neutral strange particles ($\\ko$, $\\lam$, $\\alam$) have been measured. Mean multiplicities are reported as a function of the event kinematic variables $E_\\nu$, $W^2$ and $Q^2$ as well as of the variables describing particle behaviour within a hadronic jet: $x_F$, $z$ and $p_T^2$. Decays of resonances and heavy hyperons with identified $\\ko$ and $\\lam$ in the final state have been analyzed. Clear signals corresponding to $\\rm {K^\\star}^\\pm$ $\\rm {\\Sigma^\\star}^\\pm$, $\\rm \\Xi^-$ and $\\rm \\Sigma^0$ have been observed. | 161,862 |
title: 10,000 Standard Solar Models: A Monte Carlo Simulation; abstract: We have evolved 10,000 solar models using 21 input parameters that are randomly drawn for each model from separate probability distributions for every parameter. We use the results of these models to determine the theoretical uncertainties in the predicted surface helium abundance, the profile of the sound speed versus radius, the profile of the density versus radius, the depth of the solar convective zone, the eight principal solar neutrino fluxes, and the fractions of nuclear reactions that occur in the CNO cycle or in the three branches of the p-p chains. We also determine the correlation coefficients of the neutrino fluxes for use in analysis of solar neutrino oscillations. Our calculations include the most accurate available input parameters, including radiative opacity, equation of state, and nuclear cross sections. We incorporate both the recently determined heavy element abundances recommended by Asplund et al. and the older (higher) heavy element abundances recommended by Grevesse \u0026 Sauval. We present best estimates of many characteristics of the standard solar model for both sets of recommended heavy element compositions. | 161,863 |
title: Quantum Routing of Single Photons with a Cyclic Three-Level System; abstract: We propose an experimentally accessible single-photon routing scheme using a Delta-type three-level atom embedded in quantum multichannels composed of coupled-resonator waveguides. Via the on-demand classical field being applied to the atom, the router can extract a single photon from the incident channel, and then redirect it into another. The efficient function of the perfect reflection of the single-photon signal in the incident channel is rooted in the coherent resonance and the existence of photonic bound states. | 161,864 |
title: Early chemo-dynamical evolution of dwarf galaxies deduced from enrichment of r-process elements; abstract: The abundance of elements synthesized by the rapid neutron-capture process (r-process elements) of extremely metal-poor (EMP) stars in the Local Group galaxies gives us clues to clarify the early evolutionary history of the Milky Way halo. The Local Group dwarf galaxies would have similarly evolved with building blocks of the Milky Way halo. However, how the chemo-dynamical evolution of the building blocks affects the abundance of r-process elements is not yet clear. In this paper, we perform a series of simulations using dwarf galaxy models with various dynamical times and total mass, which determine star-formation histories. We find that galaxies with dynamical times longer than 100 Myr have star formation rates less than $10^{-3} M_{\\odot}$ yr$^{-1}$ and slowly enrich metals in their early phase. These galaxies can explain the observed large scatters of r-process abundance in EMP stars in the Milky Way halo regardless of their total mass. On the other hand, the first neutron star merger appears at a higher metallicity in galaxies with a dynamical time shorter than typical neutron star merger times. The scatters of r-process elements mainly come from inhomogeneity of the metals in the interstellar medium whereas the scatters of $\\alpha$-elements are mostly due to the difference in the yield of each supernova. Our results demonstrate that the future observations of r-process elements in EMP stars will be able to constrain the early chemo-dynamical evolution of the Local Group galaxies. | 161,865 |
title: On the Habitability of Universes without Stable Deuterium; abstract: Abstract In both stars and in the early universe, the production of deuterium is the first step on the way to producing heavier nuclei. If the strong force were slightly weaker, then deuterium would not be stable, and many authors have noted that nuclesynthesis would be compromised so that helium production could not proceed through standard reaction chains. Motivated by the possibility that other regions of space-time could have different values for the fundamental constants, this paper considers stellar evolution in universes without stable deuterium and argues that such universes can remain habitable. Even in universes with no stellar nucleosynthesis, stars can form and will generate energy through gravitational contraction. Using both analytic estimates and a state-of-the-art stellar evolution code, we show that such stars can be sufficiently luminous and long-lived to support life. Stars with initial masses that exceed the Chandrasekhar mass cannot be supported by degeneracy pressure and will explode at the end of their contraction phase. The resulting explosive nucleosynthesis can thus provide the universe with some heavy elements. We also explore the possibility that helium can be produced in stellar cores through a triple-nucleon reaction that is roughly analogous to the triple-alpha reaction that operates in our universe. Stars burning hydrogen through this process are somewhat hotter than those in our universe, but otherwise play the same role. Next we show that with even trace amounts (metallicity Z ∼ 10 − 10 ) of heavy elements — produced through the triple-nucleon process or by explosive nucleosynthesis — the CNO cycle can operate and allow stars to function. Finally, we consider Big Bang Nucleosynthesis without stable deuterium and find that only trace amounts of helium are produced, with even smaller abundances of other nuclei. With stars evolving through gravitational contraction, explosive nucleosynthesis, the triple-nucleon reaction, and the CNO cycle, universes with no stable deuterium are thus potentially habitable, contrary to many previous claims. | 161,866 |
title: Magnetar activity mediated by plastic deformations of neutron star crust; abstract: We advance a \"Solar flare\" model of magnetar activity, whereas a slow evolution of the magnetic field in the upper crust, driven by electron MHD (EMHD) flows, twists the external magnetic flux tubes, producing persistent emission, bursts and flares. At the same time the neutron star crust plastically relieves the imposed magnetic field stress, limiting the strain $ \\epsilon_t $ to values well below the critical strain $ \\epsilon_{crit}$ of a brittle fracture, $ \\epsilon_t \\sim 10^{-2}\\epsilon_{crit} $. \r\nMagnetar-like behavior, occurring near the magnetic equator, takes place in all neutron stars, but to a different extent. The persistent luminosity is proportional to cubic power of the magnetic field (at a given age), and hence is hardly observable in most rotationally powered neutron stars. Giant flares can occur only if the magnetic field exceeds some threshold value, while smaller bursts and flares may take place in relatively small magnetic fields. \r\nBursts and flares are magnetospheric reconnection events that launch Alfven shocks which convert into high frequency whistlers upon hitting the neutron star surface. The resulting whistler pulse induces a strain that increases with depth both due to the increasing electron density (and the resulting slowing of the waves), and due to the increasing coherence of a whistler pulse with depth. The whistler pulse is dissipated on a time scale of approximately a day at shallow depths corresponding to $\\rho \\sim 10^{10} {\\rm g cm}^{-3}$; this energy is detected as enhanced post-flare surface emission. | 161,867 |
title: A new method to distinguish hadronically decaying boosted Z bosons from W bosons using the ATLAS detector; abstract: The distribution of particles inside hadronic jets produced in the decay of boosted W and Z bosons can be used to discriminate such jets from the continuum background. Given that a jet has been ide ... | 161,868 |
title: GROUND STATE PROPERTIES AND BUBBLE STRUCTURE OF SYNTHESIZED SUPERHEAVY NUCLEI; abstract: We calculate the ground state properties of recently synthesized superheavy elements (SHEs) from Z = 105–118 along with the predicted proton magic Z = 120. The relativistic and nonrelativistic mean field formalisms are used to evaluate the binding energy (BE), charge radius, quadrupole deformation parameter and the density distribution of nucleons. We analyzed the stability of the nuclei based on BE and neutron to proton ratio. We also studied the bubble structure which reveals the special features of the superheavy nuclei. | 161,869 |
title: Doppler-Free Two-Photon Polarization-Spectroscopic Measurement of the Stark-Broadened Profile of the Hydrogen Lα Line in a Dense Plasma; abstract: It is demonstrated that Doppler-free two-photon polarization spectroscopy makes possible Stark profile measurements without Doppler-broadened background under high-density and high-temperature conditions, e.g., in dense arc plasmas, where other sub-Doppler laser-spectroscopic techniques introduced so far fail. This method, based on the polarization rotation connected with a two-phonon transition, is not limited by collisions changing the velocity or the excitation of the atoms or by photoionization of the upper level. | 161,870 |
title: Lepton asymmetry from mixing and oscillations; abstract: We show how the two physically-distinct sources of CP-asymmetry relevant to scenarios of leptogenesis: (i) resonant mixing and (ii) oscillations between different flavours can be unambiguously identified within the Kadanoff-Baym formalism. These contributions are isolated by analyzing the spectral structure of the non-equilibrium propagators without relying on the definition of particle number densities. The mixing source is associated with the usual mass shells, whereas the oscillation source is identified with a third intermediate shell. In addition, we identify terms lying on the oscillation shell that can be interpreted as the destructive interference between mixing and oscillation. We confirm that identical shell structure is obtained in both the Heisenberg- and interaction-picture realizations of the Kadanoff-Baym formalism. In so doing, we illustrate the self-consistency and complementarity of these two approaches. The interaction-picture approach in particular has the advantage that it may be used to analyze all forms of mass spectra from quasi-degenerate through to hierarchical. | 161,871 |
title: 5D action for longitudinal five branes on a pp-wave; abstract: String modes in a pp-wave background are generically massive, and the worldvolume description of the branes is to be given by `massive\u0027 gauge theories. In this paper, we present a five dimensional super Yang-Mills action with the Kahler-Chern-Simons term plus the Myers term as a low energy worldvolume description of the longitudinal five branes in a maximally supersymmetric pp-wave background. We derive the action from the M-theory matrix model on the pp-wave. We utilize the previously found 4/32 BPS solution of rotating five branes with stacks of membranes, but, to obtain the static configuration, we reformulate the matrix model in a rotating coordinate system which provides the inertial frame for the branes. Expanding the matrix model around the solution, we first obtain a non-commutative field theory action naturally equipped with the full sixteen dynamical supersymmetries. In the commutative limit, we show only four supersymmetries survive, resulting in a novel five dimensional `` = 1/2\" theory. | 161,872 |
title: The convection-dominated magnetosphere of Uranus; abstract: In the magnetosphere of a planet which has its rotation axis aligned with the solar wind flow direction and its magnetic dipole axis significantly tilted to its rotation axis, solar-wind-driven magnetospheric convection can transport plasma throughout the magnetosphere; although corotation is present, it does not produce a closed flow region (normally identified with the plasmasphere) and thus does not Impede penetration of convection into the inner magnetosphere. The difference from the conventional theory of plasmasphere formation lies in the fact that, with the assumed geometry, the spatial pattern of magnetospheric convection is steady in the corotating rather than in the fixed frame of reference. Uranus at the present epoch closely approximates to this geometry, and hence magnetospheric convection is expected to be the dominant transport process in the Uranian magnetosphere, leading to transport times comparable to the estimated flow times of 30-40 hours. | 161,873 |
title: The influence of noise on vowel and consonant cues.; abstract: This study assessed the acoustic and perceptual effect of noise on vowel and stop-consonant spectra. Multi-talker babble and speech-shaped noise were added to vowel and stop stimuli at −5 to +10dB S/N, and the effect of noise was quantified in terms of (a) spectral envelope differences between the noisy and clean spectra in three frequency bands, (b) presence of reliable F1 and F2 information in noise, and (c) changes in burst frequency and slope. Acoustic analysis indicated that F1 was detected more reliably than F2 and the largest spectral envelope differences between the noisy and clean vowel spectra occurred in the mid-frequency band. This finding suggests that in extremely noisy conditions listeners must be relying on relatively accurate F1 frequency information along with partial F2 information to identify vowels. Stop consonant recognition remained high even at −5dB despite the disruption of burst cues due to additive noise, suggesting that listeners must be relying on other cues, perhaps formant t... | 161,874 |
title: The primary proton spectrum in the TeV region as seen by a next generation all-sky telescope; abstract: The next-generation of all-sky EAS detector will be able to lower the threshold below the TeV region and will provide a huge data flux, due to the large detecting area and the high duty cycle. In this paper we discuss in detail the possibility of using this detector in order to study the cosmic ray spectrum in the TeV region. The peculiarities of this class of next-generation detectors will make it possible to study the energy profile in the region where direct measurements are available with a large statistical significance. In such a way the measurement obtained by an indirect technique can be fully overlapped with direct measurement data, in order not only to study the cosmic ray spectrum but also to investigate the reliability of the full Monte Carlo simulation process. The sensitivity of such a measurement is also discussed and the data taking time required for a significative measurement is estimated. A standard chi-square fit and a Bayesian unfolding procedure are applied in order to obtain a measurement of the spectral index of the incoming primaries. | 161,875 |
title: Solid-particle motion in two-dimensional peristaltic flows; abstract: Some insight into the mechanism of solid-particle transport by peristalsis is sought experimentally through a two-dimensional model study (§ 2). The peristaltic wave is characterized by a single bolus sweeping by the particle, resulting in oscillatory motion of the particle. Because of fluid-particle interaction and the significant curvature in the wall wave, the peristaltic flow is highly nonlinear and time dependent. For a neutrally buoyant particle propelled along the axis of the channel by a single bolus, the net particle displacement can be either positive or negative. The instantaneous force acting upon the particle and the resultant particle trajectory are sensitive to the Reynolds number of the flow (§ 3 and 4). The net forward movement of the particle increases slightly with the particle size but decreases rapidly as the gap width of the bolus increases. The combined dynamic effects of the gap width and Reynolds number on the particle displacement are studied (§ 5). Changes in both the amplitude and the form of the wave have significant effects on particle motion. A decrease in wave amplitude along with an increase in wave speed may lead to a net retrograde particle motion (§ 6). For a non-neutrally buoyant particle, the gravitational effects on particle transport are modelled according to the ratio of the Froude number to the Reynolds number. The interaction of the particle with the wall for this case is also explored (§ 7). When the centre of the particle is off the longitudinal axis, the particle will undergo rotation as well as translation. Lateral migration of the particle is found to occur in the curvilinear flow region of the bolus, leading to a reduction in the net longitudinal transport (§ 8). The interaction of the curvilinear flow field with the particle is further discussed through comparison of flow patterns around a particle with the corresponding cases without a particle (§ 9). | 161,876 |
title: The estimation of neutrino fluxes produced by proton-proton collisions at $\sqrt{s}=14$ TeV of the LHC; abstract: Intense and collimated neutrino beams are produced by charm and beauty particle decays from proton-proton collisions at the LHC. A neutrino experiment would be run parasitically without interrupting the LHC physics program during the collider run. We estimate the neutrino fluxes from proton-proton collisions at $\\sqrt{s}=14$ TeV of the LHC with the designed luminosity, $10^{34} \\lumi$. By mounting about 200 tons of fiducial volume of a neutrino detector at 300 $\\m$ away from the interaction point, about 150,000 of charged current neutrino events per year can be observable. | 161,877 |
title: Axisymmetric black holes allowing for separation of variables in the Klein-Gordon and Hamilton-Jacobi equations; abstract: We determine the class of axisymmetric and asymptotically flat\nblack-hole spacetimes for which the test Klein-Gordon and\nHamilton-Jacobi equations allow for the separation of\nvariables. The known Kerr, Kerr-Newman, Kerr-Sen and some other\nblack-hole metrics in various theories of gravity are within\nthe class of spacetimes described here. It is shown that\nalthough the black-hole metric in the\nEinstein-dilaton-Gauss-Bonnet theory does not allow for the\nseparation of variables (at least in the considered\ncoordinates), for a number of applications it can be\neffectively approximated by a metric within the above class.\nThis gives us some hope that the class of spacetimes described\nhere may be not only generic for the known solutions allowing\nfor the separation of variables, but also a good approximation\nfor a broader class of metrics, which does not admit such\nseparation. Finally, the generic form of the axisymmetric\nmetric is expanded in the radial direction in terms of the\ncontinued fractions and the connection with other black-hole\nparametrizations is discussed. | 161,878 |
title: How Cassini can constrain tidal dissipation in Saturn; abstract: Tidal dissipation inside giant planets is important for the orbital evolution of their natural satellites. It is conventionally treated by parametrized equilibrium tidal theory, in which the tidal torque declines rapidly with distance, and orbital expansion was faster in the past. However, some Saturnian satellites are currently migrating outward faster than predicted by equilibrium tidal theory. Resonance locking between satellites and internal oscillations of Saturn naturally matches the observed migration rates. Here, we show that the resonance locking theory predicts dynamical tidal perturbations to Saturn\u0027s gravitational field in addition to those produced by equilibrium tidal bulges. We show that these perturbations can likely be detected during Cassini’s proximal orbits if migration of satellites results from resonant gravity modes, but will likely be undetectable if migration results from inertial wave attractors or dissipation of the equilibrium tide. Additionally, we show that the detection of gravity modes would place constraints on the size of the hypothetical stably stratified region in Saturn. | 161,879 |
title: Slow flow through a periodic array of spheres; abstract: Abstract Slow flow through a periodic array of spheres is studied theoretically, and the drag force by the fluid on a sphere forming the periodic array is calculated using a modification of the method developed by Hashimoto (1959). Results for the complete range of volume fraction c of spheres are given for simple cubic, body-centered cubic, and face-centered cubic arrays and these agree well with the corresponding values reported by previous investigators. Also, series expansions for the drag force to 0( c 10 ) are derived for each of these cubic arrays. The method is also applied to determine the drag force to 0( c 3 ) on infinitely long cylinders in square and hexagonal arrays. | 161,880 |
title: Finite-size effects in BaTiO3 nanowires; abstract: The size dependence of the ferroelectric properties of BaTiO3 nanowires is studied from first principles. We show that the ferroelectric distortion along the wire axis disappears below a critical diameter of about 1.2nm. This disappearance is related to a global contraction of the unit cell resulting from low atomic coordinations at the wire surface. It is shown that a ferroelectric distortion can be recovered under appropriate tensile strain conditions. | 161,881 |
title: Pulse profiles of millisecond pulsars and their Fourier amplitudes; abstract: Approximate analytical formulae are derived for the pulse profile produced by small hotspots on a rapidly rotating neutron star. Its Fourier amplitudes and phases are calculated. The proposed formalism takes into account gravitational bending of light, Doppler effect, anisotropy of emission and time delays. Its accuracy is checked with exact numerical calculations. | 161,882 |
title: Confirmation of a0(1450) and π1(1600) in p̄p→ωπ+π−π0 at rest; abstract: Abstract Crystal Barrel data are presented for p p→ωπ + π − π 0 at rest, with ω → π + π − π 0 . A small but definite signal confirms a 0 (1450) decaying to ωρ . Its branching ratio to ωρ is a factor 10.7±2.3 larger than to ηπ , where it was first identified. When fitted with a Breit–Wigner amplitude which includes the s -dependence of the ωρ channel, the pole position is M =1440 +40 −15 − i (55±7) MeV. The exotic π 1 (1600) is observed decaying to b 1 π with orbital angular momenta L =0 and 2. There is also a strong J PC =1 ++ signal consistent with a 1 (1640) decaying to ωρ and a much weaker signal for decays to [ b 1 (1235) π ] L =1 . The strongest contribution to the data is a J PC =0 −+ signal in ωρ suggesting a pole at M =1470±15− i (57±7) MeV. | 161,883 |
title: Recovery of the Schwarzschild metric in theories with localized gravity beyond linear order; abstract: We solve the Einstein equations in the Randall-Sundrum framework with a static, spherically symmetric matter distribution on the physical brane and obtain an approximate expression for the gravitational field outside the source to the second order in the gravitational coupling. This expression when confined on the physical brane coincides with the standard form of the Schwarzschild metric. Therefore, the Randall-Sundrum scenario is consistent with the Mercury precession and other tests of general relativity. | 161,884 |
title: Evidence for Increased neutron and proton excitations between 51 − 63Mn; abstract: Abstract The hyperfine structures of the odd-even 51 − 63Mn atoms ( N = 26 − 38 ) were measured using bunched beam collinear laser spectroscopy at ISOLDE, CERN. The extracted spins and magnetic dipole moments have been compared to large-scale shell-model calculations using different model spaces and effective interactions. In the case of 61,63Mn, the results show the increasing importance of neutron excitations across the N = 40 subshell closure, and of proton excitations across the Z = 28 shell gap. These measurements provide the first direct proof that proton and neutron excitations across shell gaps are playing an important role in the ground state wave functions of the neutron-rich Mn isotopes. | 161,885 |
title: Global approach to top-quark flavor-changing interactions; abstract: We adopt a fully gauge-invariant effective-field-theory approach for parametrizing top-quark flavor-changing-neutral-current interactions. It allows for a global interpretation of experimental constraints (or measurements) and the systematic treatment of higher-order quantum corrections. We discuss some recent results obtained at next-to-leading-order accuracy in QCD and perform, at that order, a first global analysis of a subset of the available experimental limits in terms of effective operator coefficients. We encourage experimental collaborations to adopt this approach and extend the analysis by using all information they have prime access to. | 161,886 |
title: Single electron emission in two-phase xenon with application to the detection of coherent neutrino-nucleus scattering; abstract: Abstract:We present an experimental study of single electron emission in ZEPLIN-III,a two-phase xenon experiment built to search for dark matter WIMPs, and discuss appli-cations enabled by the excellent signal-to-noise ratio achieved in detecting this signature.Firstly, we demonstrate a practical method for precise measurement of the free electronlifetime in liquid xenon during normal operation of these detectors. Then, using a realisticdetector response model and backgrounds, we assess the feasibility of deploying such aninstrument for measuring coherent neutrino-nucleus elastic scattering using the ionisationchannel in the few-electron regime. We conclude that it should be possible to measurethis elusive neutrino signature above an ionisation threshold of ∼3 electrons both at astopped pion source and at a nuclear reactor. Detectable signal rates are larger in thereactor case, but the triggered measurement and harder recoil energy spectrum affordedby the accelerator source enable lower overall background and fiducialisation of the activevolume.Keywords: Neutrino Detectors and Telescopes– 1 – | 161,887 |
title: Exploring leptonic CP violation by reactor and neutrino superbeam experiments; abstract: Abstract We point out the possibility that reactor measurement of θ 13 , when combined with high-statistics ν e appearance accelerator experiments, can detect leptonic CP violation. Our proposal is based on a careful statistical analysis under reasonable assumptions on systematic errors, assuming 2 years running of the neutrino mode J-PARC → Hyper-Kamiokande experiment and a few years running of a reactor experiment with 100 t detectors at the Kashiwazaki–Kariwa nuclear power plant. We show that the method can be arranged to be insensitive to the intrinsic parameter degeneracy but is affected by the one due to unknown sign of Δm 2 31 . | 161,888 |
title: Magnetoresistance and magnetic properties of La[sub 1−x]□[sub x]MnO[sub 3−δ] thin films; abstract: Epitaxial thin films of La1−x ⧠ x MnO3−δ(0≤x≤0.33) where ⧠ is a vacancy have been grown on (100) SrTiO3 substrates by pulsed laser deposition. The lanthanum deficiency results in self doping of the system without the need for divalent ion substitution. Both the films and the bulk targets used for deposition were ferromagnetic and showed giant magnetoresistance (GMR). The films increased in saturation magnetization M s and Curie temperature T c with increasing x. The T c , however, was about the same as found in Ca x substitutions. Bulk samples showed little change in M s and T c with vacancy concentration. M s in bulk samples is about half the value found in the films which have theoretical saturations for x≥0.2. GMR in the films is a few hundred percent but the bulk values are 25% at H=1.8 T. | 161,889 |
title: Using early data to illuminate the Pioneer anomaly; abstract: Analysis of the radio tracking data from the Pioneer 10/11 spacecraft at distances between about 20–70 AU from the Sun has consistently indicated the presence of an unmodelled, small, constant, Doppler blue shift drift of order 6 × 10−9 Hz s−1. After accounting for systematics, this drift can be interpreted as a constant acceleration of aP = (8.74 ± 1.33) × 10−8 cm s−2 directed towards the Sun, or perhaps as a time acceleration of at = (2.92 ± 0.44) × 10−18 s −2. Although it is suspected that there is a systematic origin to this anomaly, none has been unambiguously demonstrated. We review the current status of the anomaly, and then point out how the analysis of early data, which was never analysed in detail, could allow a clearer understanding of the origin of the anomaly, be it a systematic or a manifestation of unsuspected physics. | 161,890 |
title: INVARIANT SOLUTIONS OF EINSTEIN FIELD EQUATION FOR NONCONFORMALLY FLAT FLUID SPHERES OF EMBEDDING CLASS ONE; abstract: In the present paper, nonconformal spherical symmetric perfect fluid solutions to Einstein field equations are obtained by using the invariance of the equations under the Lie group of transformations and some new solutions of this category are obtained satisfying the reality conditions like ρ ≥ p ≥ 0, ρr \u003c 0, pr \u003c 0 (p and ρ being pressure and energy-density respectively) in the region 0 \u003c r \u003c a. Such fluids do not represent isolated fluid spheres as pressure free interface is not possible for nonconformally perfect fluids of class one. | 161,891 |
title: Summation of Parquet diagrams as an ab initio method in nuclear structure calculations; abstract: Abstract In this work we discuss the summation of the Parquet class of diagrams within Green’s function theory as a possible framework for ab initio nuclear structure calculations. The theory is presented and some numerical details are discussed, in particular the approximations employed. We apply the Parquet method to a simple model, and compare our results with those from an exact solution. The main conclusion is that even at the level of approximation presented here, the results shows good agreement with other comparable ab initio approaches. | 161,892 |
title: Various versions of analytic QCD and skeleton-motivated evaluation of observables; abstract: We present skeleton-motivated evaluation of QCD observables. The approach can be applied in analytic versions of QCD in certain classes of renormalization schemes. We present two versions of analytic QCD which can be regarded as low-energy modifications of the \u0027\u0027minimal\u0027\u0027 analytic QCD and which reproduce the measured value of the semihadronic {tau} decay ratio r{sub {tau}}. Further, we describe an approach of calculating the higher-order analytic couplings A{sub k} (k=2,3,...) on the basis of logarithmic derivatives of the analytic coupling A{sub 1}(Q{sup 2}). This approach can be applied in any version of analytic QCD. We adjust the free parameters of the aforementioned two analytic models in such a way that the skeleton-motivated evaluation reproduces the correct known values of r{sub {tau}} and of the Bjorken polarized sum rule (BjPSR) d{sub b}(Q{sup 2}) at a given point (e.g., at Q{sup 2}=2 GeV{sup 2}). We then evaluate the low-energy behavior of the Adler function d{sub v}(Q{sup 2}) and the BjPSR d{sub b}(Q{sup 2}) in the aforementioned evaluation approach, in the three analytic versions of QCD. We compare with the results obtained in the minimal analytic QCD and with the evaluation approach of Milton et al. and Shirkov. | 161,893 |
title: Direct observation of strong coupling in a dense plasma.; abstract: We present differential x-ray scattering cross sections for a radiatively heated plasma showing overall consistency, in both form and absolute value, with theoretical simulations. In particular, the evolution of the plasma from a strongly coupled high density phase to a lower density weakly coupled phase is quite clearly shown in both experiment and simulation. The success of this experiment shows that x-ray scattering has the potential to become an extremely useful diagnostic technique for dense plasma physics. | 161,894 |
title: Patterns of convection in spherical shells; abstract: The problem of the pattern of motion realized in a convectively unstable system with spherical symmetry can be considered without reference to the physical details of the system. Since the solution of the linear problem is degenerate because of the spherical homogeneity, the nonlinear terms must be taken into account in order to remove the degeneracy. The solvability condition leads to the selection of patterns distinguished by their symmetries among spherical harmonics of even order. It is shown that the corresponding convective motions set in as subcritical finite-amplitude instabilities. | 161,895 |
title: Response of distance measures to the equation of state; abstract: We show that the distance measures (such as the luminosity and angular diameter distances) are linear functionals of the equation of state function w(z) of the dark energy to a fair degree of accuracy in the regimes of interest. That is, the distance measures can be expressed as a sum of (i) a constant and (ii) an integral of a weighting function multiplied by the equation of state parameter w(z). The existence of such an accurate linear response approximation has several important implications. (1) Fitting a constant-w model to the data drawn from an evolving model has a simple interpretation as a weighted average of w(z). (2) Any polynomial (or other expansion coefficients) can also be expressed as weighted sums of the true w. (3) A replacement for the commonly used heuristic equation for the effective w, as determined by the cosmic microwave background, can be derived and the result is found to be quite close to the heuristic expression commonly used. (4) The reconstruction of w(z) by Huterer \u0026 Starkman can be expressed as a matrix inversion. In each case the limitations of the linear response approximation are explored and found to be surprisingly small. | 161,896 |
title: On the exploration of innovative concepts for fusion chamber technology; abstract: Abstract This study, called APEX, is exploring novel concepts for fusion chamber technology that can substantially improve the attractiveness of fusion energy systems. The emphasis of the study is on fundamental understanding and advancing the underlying engineering sciences, integration of the physics and engineering requirements, and enhancing innovation for the chamber technology components surrounding the plasma. The chamber technology goals in APEX include: (1) high power density capability with neutron wall load \u003e10 MW/m 2 and surface heat flux \u003e2 MW/m 2 , (2) high power conversion efficiency (\u003e40%), (3) high availability, and (4) simple technological and material constraints. Two classes of innovative concepts have emerged that offer great promise and deserve further research and development. The first class seeks to eliminate the solid “bare” first wall by flowing liquids facing the plasma. This liquid wall idea evolved during the APEX study into a number of concepts based on: (a) using liquid metals (Li or Sn–Li) or a molten salt (Flibe) as the working liquid, (b) utilizing electromagnetic, inertial and/or other types of forces to restrain the liquid against a backing wall and control the hydrodynamic flow configurations, and (c) employing a thin (∼2 cm) or thick (∼40 cm) liquid layer to remove the surface heat flux and attenuate the neutrons. These liquid wall concepts have some common features but also have widely different issues and merits. Some of the attractive features of liquid walls include the potential for: (1) high power density capability; (2) higher plasma β and stable physics regimes if liquid metals are used; (3) increased disruption survivability; (4) reduced volume of radioactive waste; (5) reduced radiation damage in structural materials; and (6) higher availability. Analyses show that not all of these potential advantages may be realized simultaneously in a single concept. However, the realization of only a subset of these advantages will result in remarkable progress toward attractive fusion energy systems. Of the many scientific and engineering issues for liquid walls, the most important are: (1) plasma–liquid interactions including both plasma–liquid surface and liquid wall–bulk plasma interactions; (2) hydrodynamic flow configuration control in complex geometries including penetrations; and (3) heat transfer at free surface and temperature control. The second class of concepts focuses on ideas for extending the capabilities, particularly the power density and operating temperature limits, of solid first walls. The most promising idea, called EVOLVE, is based on the use of a high-temperature refractory alloy (e.g. W–5% Re) with an innovative cooling scheme based on the use of the heat of vaporization of lithium. Calculations show that an evaporative system with Li at ∼1 200°C can remove the goal heat loads and result in a high power conversion efficiency. The vapor operating pressure is low, resulting in a very low operating stress in the structure. In addition, the lithium flow rate is about a factor of ten lower than that required for traditional self-cooled first wall/blanket concepts. Therefore, insulator coatings are not required. Key issues for EVOLVE include: (1) two-phase heat transfer and transport including MHD effects; (2) feasibility of fabricating entire blanket segments of W alloys; and (3) the effect of neutron irradiation on W. | 161,897 |
title: Light nuclides produced in the proton-induced spallation of U 238 at 1 GeV; abstract: The production of light and intermediate-mass nuclides formed in the reaction $^{1}\\mathrm{H}+^{238}\\mathrm{U}$ at 1 GeV was measured at the Fragment Separator at GSI, Darmstadt. The experiment was performed in inverse kinematics, by shooting a 1 A GeV $^{238}\\mathrm{U}$ beam on a thin liquid-hydrogen target. A total of 254 isotopes of all elements in the range $7\\ensuremath{\\le}Z\\ensuremath{\\le}37$ were unambiguously identified, and the velocity distributions of the produced nuclides were determined with high precision. The results show that the nuclides are produced in a very asymmetric binary decay of heavy nuclei originating from the spallation of uranium. All the features of the produced nuclides merge with the characteristics of the fission products as their mass increases. | 161,898 |
title: D0 tracking experience : From the inside looking out; abstract: Abstract We describe the design, construction, and operation of the D0 detector and its upgrades at the Fermilab Tevatron Collider. | 161,899 |
Subsets and Splits