221 research outputs found

    Inverse Scattering Problem for Vector Fields and the Cauchy Problem for the Heavenly Equation

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    We solve the inverse scattering problem for multidimensional vector fields and we use this result to construct the formal solution of the Cauchy problem for the second heavenly equation of Plebanski, a scalar nonlinear partial differential equation in four dimensions relevant in General Relativity, which arises from the commutation of multidimensional Hamiltonian vector fields.Comment: 15 pages, submitted to Phisics Letters A. This paper replaces nlin.SI/051204

    Perspective Method of Betavoltaic Converter Creation

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    Some results on planar diode structure creation by the method of a plasma-immersion ion implantation is presented in this paper. Obtained leakage current ~ 1 uA/cm2 at reverse voltage – 1 V. The cryogenic plasmochemical silicon etching process is developed, able to form the structured silicon layer with system of deep holes with high aspect ratio

    Structural-phase transformations in magnetron deposited films of Ti-Zr-Ni systems during annealing in vacuum

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    Structural and phase changes in thin films obtained by magnetron sputtering of a target with the composition Ti41Zr38.3Ni20.7 (at.%) were studied under isothermal vacuum annealing in the temperature range from 400 to 800 °C. The boundaries of the thermal stability of the phases have been determined. Coatings consisting of a single icosahedral quasicrystalline phase, as well as films consisting of the 2/1 crystal-approximant phase were obtained. The features of the phase transformation of a quasicrystal into an approximant crystal were investigated, and the activation energy of this transformation was determined at a level of 94 kJ/mol. The dependence of the degree of phase transformation on the temperature and duration of annealing has been established.Досліджено структурно-фазові зміни в тонких плівках, отриманих магнетронним розпиленням мішені складу Ti41Zr38,3Ni20,7 (ат.%), при ізотермічних вакуумних відпалах в інтервалі температур 400…800 °C. Визначено межі термічної стабільності фаз. Отримано однофазні покриття з ікосаедричної квазікристалічної фази, а також з фази кристала-апроксиманта 2/1. Досліджено характер фазового перетворення квазікристала в кристал-апроксимант, і визначена енергія активації цього перетворення на рівні 94 кДж/моль. Встановлено залежність ступеня фазового перетворення від температури і тривалості відпалу.Исследованы структурно-фазовые изменения в тонких плeнках, полученных магнетронным распылением мишени состава Ti41Zr38,3Ni20,7 (ат.%), при изотермических вакуумных отжигах в интервале температур 400…800 °C. Определены границы термической стабильности фаз. Получены однофазные покрытия из икосаэдрической квазикристаллической фазы, а также из фазы кристалла-аппроксиманта 2/1. Исследован характер фазового превращения квазикристалла в кристалл-аппроксимант, и определена энергия активации этого превращения на уровне 94 кДж/моль. Установлена зависимость степени фазового превращения от температуры и продолжительности отжига

    Effects of exposure of rat erythrocytes to a hypogeomagnetic field

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    The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Background:Hypomagnetic fields can disrupts the normal functioning of living organisms by a mechanism thought to involve oxidative stress. In erythrocytes, oxidative stress can inter alia lead to changes to hemoglobin content and to hemolysis. Objective:To study the effects of hypomagnetism on the state of rat erythrocytes in vitro. Methods:Rat erythrocytes were exposed to an attenuated magnetic field (AMF) or Earth’s magnetic field (EMF), in the presence of tert-butyl hydroperoxide (TBHP) as inducer of oxidative stress. Determinations: total hemoglobin (and its three forms – oxyhemoglobin, methemoglobin, and hemichrome) released from erythrocytes, spectral data (500–700 nm); oxygen radical concentrations, electron paramagnetic resonance. Results:AMF and EMF exposed erythrocytes were compared. After 4 h incubation at high TBHP concentrations (>700 μM), AMF exposed erythrocytes released significantly more (p<0.05) hemoglobin (Hb), mostly as methemoglobin (metHb). Conversely, after 24 h incubation at low TBHP concentrations (⩽350 μM), EMF exposed erythrocytes released significantly more (p<0.001) hemoglobin, with metHb as a significant proportion of the total Hb. Erythrocytes exposed to AMF generated more radicals than those exposed to the EMF. Conclusion:Under particular conditions of oxidative stress, hypomagnetic fields can disrupt the functional state of erythrocytes and promote cell death; an additive effect is implicated

    Mass-renormalized electronic excitations at (π\pi, 0) in the superconducting state of Bi2Sr2CaCu2O8+δBi_{2}Sr_{2}CaCu_{2}O_{8+\delta}

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    Using high-resolution angle-resolved photoemission spectroscopy on Bi2Sr2CaCu2O8+δBi_{2}Sr_{2}CaCu_{2}O_{8+\delta}, we have made the first observation of a mass renormalization or "kink" in the E vs. k\vec k dispersion relation localized near (π,0)(\pi, 0). Compared to the kink observed along the nodal direction, this new effect is clearly stronger, appears at a lower energy near 40 meV, and is only present in the superconducting state. The kink energy scale defines a cutoff below which well-defined quasiparticle excitations occur. This effect is likely due to coupling to a bosonic excitation, with the most plausible candidate being the magnetic resonance mode observed in inelastic neutron scattering

    Origin of the photoemission final-state effects in Bi2Sr2CaCu2O8 by very-low-energy electron diffraction

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    Very-low-energy electron diffraction with a support of full-potential band calculations is used to achieve the energy positions, K// dispersions, lifetimes and Fourier compositions of the photoemission final states in Bi2Sr2CaCu2O8 at low excitation energies. Highly structured final states explain the dramatic matrix element effects in photoemission. Intense c(2x2) diffraction reveals a significant extrinsic contribution to the shadow Fermi surface. The final-state diffraction effects can be utilized to tune the photoemission experiment on specific valence states or Fermi surface replicas.Comment: 4 pages, 3 Postscript figures, submitted to Phys. Rev. Lett; major revision

    From nonassociativity to solutions of the KP hierarchy

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    A recently observed relation between 'weakly nonassociative' algebras A (for which the associator (A,A^2,A) vanishes) and the KP hierarchy (with dependent variable in the middle nucleus A' of A) is recalled. For any such algebra there is a nonassociative hierarchy of ODEs, the solutions of which determine solutions of the KP hierarchy. In a special case, and with A' a matrix algebra, this becomes a matrix Riccati hierarchy which is easily solved. The matrix solution then leads to solutions of the scalar KP hierarchy. We discuss some classes of solutions obtained in this way.Comment: 7 pages, 4 figures, International Colloquium 'Integrable Systems and Quantum Symmetries', Prague, 15-17 June 200

    Optical symmetries and anisotropic transport in high-Tc superconductors

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    A simple symmetry analysis of in-plane and out-of-plane transport in a family of high temperature superconductors is presented. It is shown that generalized scaling relations exist between the low frequency electronic Raman response and the low frequency in-plane and out-of-plane conductivities in both the normal and superconducting states of the cuprates. Specifically, for both the normal and superconducting state, the temperature dependence of the low frequency B1gB_{1g} Raman slope scales with the cc-axis conductivity, while the B2gB_{2g} Raman slope scales with the in-plane conductivity. Comparison with experiments in the normal state of Bi-2212 and Y-123 imply that the nodal transport is largely doping independent and metallic, while transport near the BZ axes is governed by a quantum critical point near doping p0.22p\sim 0.22 holes per CuO2_{2} plaquette. Important differences for La-214 are discussed. It is also shown that the cc- axis conductivity rise for TTcT\ll T_{c} is a consequence of partial conservation of in-plane momentum for out-of-plane transport.Comment: 16 pages, 8 Figures (3 pages added, new discussion on pseudogap and charge ordering in La214

    Long-range Angular Correlations On The Near And Away Side In P-pb Collisions At √snn=5.02 Tev

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    7191/Mar294

    (Anti-)deuteron production in pp collisions at 1as=13TeV

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    The study of (anti-)deuteron production in pp collisions has proven to be a powerful tool to investigate the formation mechanism of loosely bound states in high-energy hadronic collisions. In this paper the production of (anti-)deuterons is studied as a function of the charged particle multiplicity in inelastic pp collisions at s=13 TeV using the ALICE experiment. Thanks to the large number of accumulated minimum bias events, it has been possible to measure (anti-)deuteron production in pp collisions up to the same charged particle multiplicity (d Nch/ d \u3b7 3c 26) as measured in p\u2013Pb collisions at similar centre-of-mass energies. Within the uncertainties, the deuteron yield in pp collisions resembles the one in p\u2013Pb interactions, suggesting a common formation mechanism behind the production of light nuclei in hadronic interactions. In this context the measurements are compared with the expectations of coalescence and statistical hadronisation models (SHM)
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