The paramagnetic susceptibility of rare-earth metal compounds, such as Er$_{1-x}$Ho$_x$Rh$_4$B$_4$, is studied in terms of the microscopic theory of complex compounds. It is shown that the inverse statistical susceptibility of these systems obeys the Curie-Weiss law, with the Curie temperature being determined by the exchange interaction in the self-consistent approximation. The obtained results are compared with experimental data.
Show AbstractA method for Casimir pressure calculation with the help of the regular part of the Green surface function is considered in the two-dimensional case. Also, a method for the approximate calculation of the regular part of the Green surface function using a Born-type series is suggested. It is tested for a problem for which the exact solution is known.
Show AbstractFor the $N=1$ supersymmetric electrodynamics it is shown that if the Gell-Mann-Low function coincides with the exact Novikov-Shifman-Vainstein-Zakharov β-function (NSVZ β-function), then the sum of some effective diagrams with vertices of three and four points is zero.
Show AbstractA special vector functional space is defined for a weak formulation of the diffraction problem in a cone. For this space, a number of embedding theorems are proved. It is also shown that the diffraction problem is reduced to the Fredholm equation.
Show AbstractThe integral $\int_\Omega\Phi\Psi\,d\Omega$ taken over an arbitrary plane region $\Omega$ where the scalar functions of the point $\Phi$ and $\Psi$ are the solutions of the Helmholtz two-dimensional equation is presented as a contour, i.e., in the invariant view and in three main orthogonal coordinate systems on a plane, namely, in the Cartesian, polar, and elliptic coordinate systems. An invariant expression in the view of the contour integral for power flow of the guided mode through an arbitrary region of the cross section of a waveguide with constant permittivity has been obtained.
Show AbstractWeak radiative hyperon decays are considered in the unitary and quark models. The problem of transition from one model to the other one is solved both for parity-violating and parity-conserving amplitudes. This eliminates the contradiction of incompatibility of these descriptions, which has been discussed for more than 20 years. The model is phenomenological and describes the experimental data well; it gives predictions for asymmetry of$\Lambda\to n+\gamma$ and $\Xi^{-}\to\Sigma^{-}+\gamma$ decays.
Show AbstractThe effects of a minimal supersymmetric model with the Yukawa sector of the second type and explicit violation of $CP$ invariance in the Higgs potential occurring during the mixing of physical states in systems of neutral $B^0_{d,s}$ mesons are considered. The mixing parameter $\Delta m_{LS}$ is calculated in the limit of four-fermion approximation with the exchange of charged Higgs bosons ($H^\pm$). This study specifies data presented in [1] and establishes new constraints on
Show AbstractAn experiment on the irradiation of the natural mixture of $^{203,205}$Tl isotopes by the bremsstrahlung beam of pulsed racetrack microtron RTM-70 (Skobeltsyn Institute of Nuclear Physics, Moscow State University) at an electron energy of 67.7 MeV was performed. The yields and integral cross sections of multiparticle photonuclear reactions with $^{203,205}$l isotopes were measured.
Show AbstractA method is developed for calculating the frequency dependences of the Bragg angle in two-dimensional photonic crystals for isotropic and anisotropic Bragg diffractions. It is shown that the frequency dependences of the Bragg angle exhibit some interesting features related to the formation of partial forbidden bands of optical and acoustic waves.
Show AbstractSimple analytical expressions for the effective refractive index of an aperiodic thin-layer structure have been obtained and analyzed. The expressions correctly describe the optical properties of the structure in a wide range of wavelengths. The optical properties that are general for the structures of this class have been established. The validity of the results is shown by a numerical experiment.
Show AbstractA new approach is proposed to the modeling of magnetohydrodynamic and chemical processes involved in aluminum electrolysis. In this approach a medium under study is presented as a mixture of reagents in unknown concentrations, making it possible to describe mixing and the chemical interaction of the electrolyte and the metal melt. Therefore, all stages of the electrolysis process can be modeled over a long interval of time.
Show AbstractAn analytical formula for an adjustment function, taking the violation of adiabatic conditions in the dynamic measurements of the adiabatic thermal pressure coefficient for conducting liquids [1] into account, has been obtained. The formula is corroborated by numerical calculation. It has been shown that the correction can be on the order of 1 to 7%, depending on the electroconductivity of the material and geometry of the experiment. The determination of the adjustment function is of great importance in the study of structural transitions in metallic liquids.
Show AbstractFor weakly localized electrons in disordered granular materials, the wave function decay length that determines the spatial decrease of the wave functions in the superlocalization mode is calculated. The dependence of the decay length on the energy and structural parameters of the system is established.
Show AbstractThe elementary processes of crystal growth in the case of a low kink density on step edges have been studied by in situ atomic force microscopy. High-resolution images of the first turn of the polygonal dislocation spiral on the (101) face of monoclinic lysozyme crystals, which allow one to discern separate crystal cells, have been obtained. It has been shown that the dependence of the spiral segment velocity on its length is inconsistent with the Gibbs-Thomson law and is represented by several rectilinear sections. The results were explained by taking into account the features of the growth of crystals with a low kink density at low supersaturation.
Show AbstractThe problem of the evolution of a single vortex in a nonequilibrium medium with a temperature-or density-dependent energy release was solved. In a medium that is stable against small perturbations, the vortex passes to a new stationary state, and no vortex breakdown occurs. For a temperature-dependent energy release, analytical solutions that define changes in the characteristics of the vortex were obtained for high and low relaxation times. The solutions were compared with the results of numerical simulation by the Godunov method.
Show AbstractFibrin clots are characterized by low permeability, which affects the spatial aspects of the coagulation process. Between blood plasma albumins noncovalent interactions are possible. The hypothesis that albumin accumulates in clots was examined. It was shown that albumin can not bind with fibrin clots in noticeable quantities, i.e., its presence has no impact on clot permeability neither during formation nor after-wards. During filtration at the free clot boundary a hardening zone resembling compacted clots in its permeability is formed.
Show AbstractThe spectra and spectroheliograms in the He I λ = 1083.03 nm IR-line obtained with the horizontal solar telescope of the Sternberg State Astronomical Institute (SSAI) of Moscow State University are analyzed for the purpose of studying the increased solar activity at the boundaries of coronal holes. Our observations demonstrate plasma flux intensification at the boundary separating a coronal hole and a bipolar active region. In this case, the spectra in the vicinity of the He I λ = 1083.03 nm line point to a significant intensification in the lines of light isotope $^3$He I λ = 1083.168 nm and Fe I λ = 1082.837 nm. Acceleration of solar plasma fluxes at the coronal hole boundary in the immediate vicinity of an active region seems to be the result of reconnection of bipolar structure magnetic fields in the active region and a unipolar field of the coronal hole. The nature of $^3$He and Fe I particle enrichment in upward fluxes at the coronal hole boundaries is discussed.
Show AbstractIn many modern papers devoted to the calculation of radio emissions from extensive atmospheric showers (EASs) in the 10–100 MHz range, the radiation from EASs of charged particles moving with a velocity higher than the speed of light in air is identified as Vavilov-Cherenkov radiation (VCR). In this paper it is shown that radio emissions from EASs at frequencies less than 100 MHz do not possess the properties of VCR recorded from EASs in the optical range.
Show AbstractThe behavior of two-sublattice natural ferromagnetics under the effects of static and variable fields and high and low temperatures is studied. Novel unknown peculiarities of thermoremanent magnetization (TRM) and partial thermoremanent magnetization (pTRM) dependences on fields and temperatures are obtained. Self-reversal of TM and pTRM in the sample, where self-reversal has not been observed prior to the application of fields and temperatures, is revealed.
Show AbstractThe supersonic air flow at Mach numbers of 1.1–1.6 in a shock tube is experimentally investigated during initiation of nanosecond pulse surface sliding discharges. The shadow images of the flow field after discharge initiation, which characterize the dynamics of shock waves propagating from the discharge area, are obtained. Periodic pressure pulsations on the shock tube channel wall are recorded. The pressure dynamics is shown to correspond to both the motion of shock waves from the discharge area and a supersonic flow of the discharge-excited gas near the channel wall. The pressure increase on the shock tube channel wall was 6–18%, as compared to the pressure in an unperturbed flow.
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