[en] Approximate dispersion relations for electromagnetic waves propagating in a gyrotropic and anisotropic periodically heterogeneous medium have been obtained. Expressions for amplitudes and angular distribution of scattered radiation maxima have been derived in the case of waves passing through a thin anisotropic plate. The results have been generalized for the case of a spatially confined anisotropic body

No abstract available

[en] The phenomenon of focusing and defocusing of diffracted X radiation with different wave fronts in crystals under the action of temperature gradient and ultrasonic oscillations has been investigated in detail

[en] The radiation emitted by channeled positrons in a longitudinal or transverse standing hypersonic wave field is considered. In the case of plane channeling the spectral distribution of the radiation intensity is shown to be of a resonance nature depending on the hypersound frequency

[en] An origin of jump-like and hysteresical phenomena is predicted theoretically. Those are caused by the ruling of the state of non-linear anisotropic resonator with an orthogonal polarization of light waves. The resonator creates a turned connection as well as causes a complex tying between the waves. The later conditions a whole number of the interacting waves regimes because of a big number of ruling parameters. 5 refs

[en] The scattering of X-rays on a crystal is considered in grazing geometry when a surface acoustic wave is excited normal to the diffraction vector. The intensity of wave field at finite distance from crystal to detector is obtained. It is shown that in the presence of surface acoustic wave the magnitude of the main peak of specular reflected diffracted wave intensity decreases and intensity of satellites increases. The main peak of specular reflected diffracted wave intensity is split up as the grazing observation angle increases

[en] The use of a sound wave created by an external source and directed along the positive column of a nitrogen discharge in order to make the discharge pass to the contracted state is studied experimentally. A phenomenon involving a jump in the sound wave amplitude, caused by the discharge contraction, is observed and studied. It is established that the amplitude of the sound wave as a function of the discharge current near the jump exhibits hysteresis. It is shown that in the field of a high-intensity sound wave causing the discharge to expand eliminates the jump in the sound amplitude. The dependence of the growth time of the sound amplitude caused by the jump in this quantity on the sound wave intensity is determined. 24 refs., 4 figs., 1 tab

No abstract available

[en] The paper deals with the problem of neutron diffraction in a quartz single crystal under the action of acoustic oscillations or a temperature gradient in the Laue geometry. Theoretical conclusions were compared with experimental results

[en] Approximate analytic solutions are found in the most general formulation of the problem of incoherent radiative transfer in a one-dimensional medium of finite optical thickness for the model of complete frequency redistribution. The accuracy of these solutions increases with increasing thickness of the layer, with decreasing probability of photon survival, and with closer approach of the frequency to the line center. In the worst case their error is of the order of a few percent. These solutions are illustrated by the example of calculation of Ambartsumyan's Phi and Psi functions for Doppler and Lorentz profiles of the spectral line