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[en] The interaction between plane electromagnetic and gravitation waves is studied. It is shown on basis of the Einstein equations that empty space-time, which admits the absolute parallel Killing field, reduces to the Peres solution. The equations for small gravitation and electromagnetic field perturbations against the background of a strong plane electromagnetic wave are considered in the Newman-Penrose formalism. The equations can be reduced to a set of two second order equations with respect to the tetrad components of the Weyl tensor and the Maxwell tensor. Explicit solutions are obtained for the cases when weak plane gravitational and electromagnetic waves are incident on a strong wave

[en] Fields are considered which exhibit the nonpolynomial growth in a momentum representation, in other words, the order of singularity of which in a coordinate representation is infinite. A method for describing local properties of fields of arbitrary singularity is suggested. Special attention is paid to the degree in which the unity expansion is transferred over non-localizable test functions. The way how local properties are weakened as the singularity increases is demonstrated. The results obtained are applied to the Wightman functions. It is shown that the magnitude of the region of holomorphy of the Wightman functions as well as its very existence depend directly on local properties of the theory. The results make it possible to obtain a simple proof of the theorem of the space-like asymptotics for Vacuum average values which is valid both for localizable and for nonlocalizable theories. The theorem of the space-like asymptotics is used for the proof of the polynomial limitation over energy of the elastic scattering amplitude and of its analyticity over momentum transfer

[en] Taking as an example a static spherically symmetric gravitational field having a metric, which is gallilean on infinity, it has been shown the nonuniqueness of the ''harmonic'' solutions of the Einstein equations. Throughout the space under nonsideration both inside and outside a spherical symmetric body, which is in euqilibrium, it is possible to introduce a single-parameter family of harmonic coordinates corresponding to these solutions

[en] The paper presents a brief account of a work on the renormalization of the nonlinear sigma-model with O (n) symmetry and its application, in statistical mechanics, to the phase transition of the classical Heisenberg ferromagnet. Some simplified arguments explaining the role of dimension 1 and 2 for the Ising and Heisenberg model respectively are given

[en] Conditions of the experiments are considered for observation of parity nonconservation in radiative atomic transitions in the case of hydrogen - like atoms and two-electron ions. Calculations are carried out for H, He C⁺³ and Cu ⁺²⁷ limitations on a beam and residual gass density, external magnetic and electric fields are calculated. The time of the experiment is also estimated. The conditions appear to be really practible only in the case of Cu⁺²⁷

[en] Anomalous photoconductivity (AP) in n-InSe single crystals has been experimentally investigated for various orientations of an electric field and light relative to the hexagonal axis of a crystal. Measurements have been taken at temperatures of T (<=) K. As a result, it is found that AP in single crystals studied in the longitudinal regime does not differ essentially from AP for the single crystals in the transverse regime. AP does not also depend on the direction of a lighting beam, on its spectrum and on the thickness of a sample. The results make it possible to conclude that the potential barriers responsible for the AP in the single crystals are caused by chaotic macroscopic barriers arising due to strong self-compensation

[en] A technique for calculating the energy of the ground state of an electron-hole liquid in idealized laminated semiconductors is presented. A model is considered by which a semiconductor is presented as the infinite number of parallel planes containing equal quantity of nonequilibrium electrons and holes. The electron and hole transitions from one plane into another are forbidden. The band structure dependent expression for calculating the energy of the ground state is derived. The binding energy of the electron-hole liquid is found to increase rapidly with the decrease of dielectric permittivity and effective electron mass to effective hole mass ratio and also with the increase of the number of electron and hole valleys. This fact shows that layered semiconductors can be unstable with respect to the phase transition of the first type into metallic state at the binding energy approaching the energy gap

No abstract available

No abstract available