Numerical solution of the Slonczewski equations were used to study the motion of an individual domain wall in a two-layer uniaxial film in which the damping parameter and the gyromagnetic ratio depend on the specific layer.
Show AbstractThe decay of mesons $K^{+}\to\pi^{-}\ell^{+}{\ell'}^{+}$ and $D^{+}\to K^{-}\ell^{+}{\ell'}^{+}$ ($\ell,\ell'=e,\mu$) involving a change of lepton number ${\Delta L=2}$ is considered in a supersymmetric extension of the standard model in which $R$-parity is not conserved due to trilinear Yukawa interactions. The obtained estimates for the probabilities of these decays are significantly lower than the direct experimental upper limits.
Show AbstractThe helicity of adjacent phase trajectories in chaotic dynamic systems may be characterized by the distribution of local angular-rotation velocities of the infinitesimal displacement vector whose evolution is determined by linearized equations of motion. This distribution is close to the distribution of local Lyapunov exponents. The simplest models show that the whirl velocity of adjacent trajectories affects the rate of mixing of dynamical variables and sensitivity of the phase trajectories to perturbations.
Show AbstractAn explicit form of the Killing spinor (generator of N = 1 sypersymmetry) is found for a nondegenerate deformed conifold [3].
Show AbstractApproximation formulas are obtained for calculation of the gas flow rate in long isothermal microchannels. The quasi-gas-dynamic equations with Maxwell’s slip conditions are shown to predict a minimum in the flow rate within a channel that is called the Knudsen minimum. Corrections are proposed enabling derivation of approximate formulas for flow rates valid for any Knudsen number.
Show AbstractA concept of co-sheaf of Sobolev spaces, which generalizes the concept of Sobolev space, is introduced. A generalization of the Rellich-Friedrichs theorem that covers operators of boundary value problems in unbounded domains, in particular, waveguides, is established.
Show AbstractThe method of numerical integration of the classical equations of motion was used to study interaction of a model two-electron atom with ultrashort laser pulses. Mechanisms and specific features of the ionization process were analyzed in a broad range of laser-field parameters.
Show AbstractThe shape of the particle quantity spectrum of giant air cosmic-ray showers is studied. The Nishimura-Kamata-Greisen function describing the spatial distribution in the electron-photon cascade theory and the function calculated in [1] taking into account the nuclear-cascade process are considered.
Show AbstractThe luminescence spectra of single-crystal films and bulk crystals of yttrium-aluminum garnet Y$_3$Al$_5$O$_{12}$ and Ce$^{3+}$-activated Y$_3$Al$_5$O$_{12}$ were investigated. It was shown that the room-temperature luminescence intensity of theCe$^{3+}$-free single-crystal Y$_3$Al$_5$O$_{12}$ film was considerably lower than that of the bulk crystals, while the luminescence intensity of the Ce$^{3+}$ ions in the Y$_3$Al$_5$O$_{12}$:Ce films was considerably higher than that one for the corresponding bulk crystal.
Show AbstractBased on the method of discrete sources, a mathematical model for the analysis of the spectral characteristics of the scattering of nonradiative waves by nanodimensional rods arranged on the surface of a glass prism was constructed. It was shown that the spectral characteristics significantly depend on both the elongation of the rods and their orientation.
Show AbstractA new method using modal phase tomography for diagnosis of human eye aberration was elaborated and investigated. The method enabled the separation of the contributions from the individual elements of the eye into summary aberrations. The forms of the radiation wavefronts from several reference sources being formed on the retina of the eye as initial data for analysis were considered. Distortions of every element of the eye were represented as a Tsernike polynomial expansion. In this work, the theoretical basis of the method, numerical investigation and experimental modeling results confirming the efficiency of the method are presented.
Show AbstractRoom-temperature piezoelectric moduli of a new high-temperature ferroelectric crystal, LaBGeO$_5$(LBGO), are for the first time determined experimentally. It is shown that the piezoactivity of this crystal is close to that of quartz. Comparative analysis of temperature dependences of spontaneous polarization and spontaneous deformation was carried out, and the piezomoduli were measured at room temperature. Based on these data, it was shown that this crystal, which undergoes the change of symmetry 32 → 3 during the phase transition ($T_c=533^{\circ}$C), is not a multiferroelectric. Its “transient” piezomoduli should not undergo noticeable anomalies at the Curie point, and the dependence d 3i ∼ (T c − T)−1/2, which is common for uniaxial ferroelectrics, is expected for morphic piezomoduli associated with polarization along axis 3.
Show AbstractSelf-reversal of thermal magnetization in natural ferrite (a solid solution of the magnetite and maghemite with Curie temperature of 595°C) was studied. The experimental results show that self-reversal occurs as a result of the effect of negative exchange anisotropy in the vicinity of the Curie temperature via a mechanism related to the presence of a weak magnetic sublattice in ferrite.
Show AbstractThe spectra of protons with energies from 10 keV to 1 MeV as measured in experiments conducted at satellites and the MIR orbital station are presented. These data were obtained in the area of the geomagnetic equator at L < 1.15 and at altitudes up to 1000 km. The proton spectrum was determined during periods of geomagnetic perturbations and quite periods. These spectra were approximated using a kappa-function. The proton spectra in the near-equatorial area and in the ring current are compared. The proton’s life time in the near-equatorial area is estimated, taking into account charge exchange and Coulomb scattering. It is confirmed that the ring current is a main source of protons in the near-equatorial area at low altitudes.
Show AbstractSolutions of bovine serum albumin with metal ions Pb$^{2+}$ and Na$^{+}$ were studied by fluorescence analysis in the visible and UV ranges in relation to such parameters of the medium as the concentration of macromolecules, the pH, and the ionic strength of the solution. The formation of nanoparticles, protein clusters, in aqueous solutions of albumin containing ions of such a heavy metal as lead was revealed by fluorescence polarization analysis. This investigation is of practical value for the solution of ecological and medical problems.
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