Study of the peak effect phenomenon in single crystals of 2H-NbSe2

The weakly pinned single crystals of the hexagonal 2H-NbSe₂ compound have emerged as prototypes for determining and characterizing the phase boundaries of the possible order-disorder transformations in the vortex matter. We present here a status report based on the ac and dc magnetization measurements of the peak effect phenomenon in three crystals of 2H-NbSe₂, in which the critical current densities vary over two orders of magnitude. We sketch the generic vortex phase diagram of a weakly pinned superconductor, which also utilizes theoretical proposals. We also establish the connection between the metastability effects and pinning.     

Fabry-Perot cavity in the field of a gravitational wave

The structure of the electromagnetic field inside a laser cavity—a gravitational-wave detector—is studied. The properties of the spatial and temporal phases of the standing electromagnetic wave are discussed in detail and the corrections appearing in the electric field of the wave as a result of the action of gravitational radiation on the optical system are determined. Zh. éksp. Teor. Fiz. 113, 398–408 (February 1998)     

Investigation of the effects of hydration and amphiphilic properties of nootropic drugs of piracetam and pramiracetam

An investigation of the hydration and amphiphilic properties of the piracetam and pramiracetam molecules has been conducted by theoretical conformational analysis and the Monte Carlo method; their localization and orientation at the water-lipophilic medium interface have been determined, which made it possible to explain the characteristics of the pharmacological action of the drugs.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 28, No. 4, pp. 355–358, July–August, 1992.     

Dynamics of domain walls in bismuth-ytterbium-containing garnet ferrite films in the vicinity of the angular momentum compensation point

The dependence of the domain-wall velocity V on the acting magnetic field H is investigated for (Bi,Yb)₃(Fe,Ga)₅O₁₂ garnet ferrite single-crystal films in the vicinity of the angular momentum compensation point at different temperatures. The films are grown by liquid-phase epitaxy from a supercooled solution melt on Cd₃Ga₅O₁₂ substrates with the (111) orientation. It is demonstrated that, in these films, the precessional mechanism is not responsible for the motion of domain walls but there arises an internal effective magnetic field that weakens the acting magnetic field.     

The influence of a transverse magnetic field on a subnormal glow discharge in air

In subnormal glow discharge under d.c. excitation at different pressure in a varying transverse magnetic field (0 to 30 G) some measurements have been carried out for various initial average tube currents. The voltage across the discharge increases and average tube current and residual current decreases in the magnetic field. With the help of Beckman’s expression [4] for the axial field and the electron density distribution in a transverse magnetic field the observed variation of current and voltage can be satisfactorily explained. The variation of axial electric field with transverse magnetic field can be represented to a fair degree of accuracy by the derived equation. The behaviour of residual current with magnetic field has been observed in these oscillations.     

Integral equation formulation for buoyancy-driven convection problems

An integral equation formulation for buoyancy-driven convection problems is developed and illustrated. Buoyancy-driven convection in a bounded cylindrical geometry with a free surface is studied for a range of aspect ratios and Nusselt numbers. The critical Rayleigh number, the nature of the cellular motion, and the heat transfer enhancement are computed using linear theory. Green's functions are used to convert the linear problem into linear Fredholm integral equations. Theorems are proved which establish the properties of the eigenvalues and eigenfunctions of the linear integral operator which appears in these equations.     

Application of Haar functions with cyclic translations in the search for cosmic strings

Cosmic strings are theoretically predicted linear structures of a cosmological size. The search for cosmic strings in optical and radio observations has been an important area of research in recent years. One of the most effective methods of searching for these objects is the analysis of the anisotropy of cosmic microwave background radiation that could be induced by cosmic strings. For this purpose, the authors propose a method of signal expansion in modified Haar functions with cyclic translations. However, for a system of these functions to be used correctly, one needs to prove its orthonormality and completeness, which is the purpose of this paper.     

The apparent motions of extragalactic sources and their angular spectrums

The apparent motions of extragalactic ICRF sources are considered. Computer simulation of apparent motions is carried out assuming that they are stochastic and uncorrelated, while the position angle of the velocity for each source has a uniform distribution. We calculate the vector amplitudes of spherical harmonics and show that the corresponding spectrum has the form of “white noise.” In addition, we discuss observational data and calculate their angular spectra. Preliminary conclusions on the origin of the observed multipolar harmonics in the velocity angular spectrum are given.     

Effect of the magnetic field in the plane of a garnet ferrite film with orthorhombic magnetic anisotropy on the dynamics of domain walls

The effect of an in-plane magnetic field on the dependence of the domain-wall velocity on the acting magnetic field is investigated for bismuth-containing garnet ferrite single-crystal films of the composition (Bi,Y,Pr)₃(Fe,Ga)₅O₁₂ with the (210) orientation. The in-plane magnetic field is applied along the 〈120〉 and 〈001〉 crystallographic axes. The domain-wall velocity is measured in directions perpendicular and parallel to the in-plane magnetic field.