R e g u l a r p a p e r s

Moscow University Physics Bulletin 1971. **26**. N 1. P. 1

The nonlinear phenomenological fluctuation-dissipation thermodynamics developed previously in [1] applied to mechanical systems described by a given Hamiltonian. Thermodynamic relations of linearquadratic and cubic theories are given. Some of the results are expressed in terms of a dissipative function.

Show AbstractMoscow University Physics Bulletin 1971. **26**. N 1. P. 8

Photoemission from a metal surface is analyzed in the presence of a constant external electric field of relatively low intensity. In contrast with the case of thermionic emission, the effect of the electricfield is not simply to reduce the worked function. The physical causes of this difference are analyzed, and a correct expression for the photofield-emission current is derived and analyzed.

Show AbstractMoscow University Physics Bulletin 1971. **26**. N 1. P. 13

Reception employing spatial-frequency separation has been used along with three-dimensional correlation analysis to study the size, orientation, and motion of small-scale inhomogeneities in the ionosphere. The results obtained by this method are compared with those obtained by spatial separation alone.

Show AbstractMoscow University Physics Bulletin 1971. **26**. N 1. P. 18

The differential equations for the elements of an intermediate orbit are integrated on the basis of the solution of the generalized problem of two fixed centers. The right side of these equations contain the components of the perturbing acceleration caused by atmospheric drag. Equations are derived for the perturbations in the orbital elements with the atmospheric drag.

Show AbstractMoscow University Physics Bulletin 1971. **26**. N 1. P. 23

An analysis is made of the possible acoustic insulation of a vibrating surface under conditions corresponding to underwater-sound experiments by covering the outside of the surface with a thin covering of an acoustically soft material. A theoretical analysis is made of the vibrations of an infinite cylindrical shell having nodal lines parallel to the axis on the surface of the cylinder. It is found that the radiation can be reduced for each vibrational mode in a certain frequency range, governed by the geometry of the cylindrical surface and covering and by the properties of the covering material.

Show AbstractMoscow University Physics Bulletin 1971. **26**. N 1. P. 29

Nonequilibrium low-frequency fluctuations in the current and electron temperature. The nonequilibrium nature of the fluctuations results from the imposition of an external electricfield. Explicit expressions are found for the spectral functions for the current and electron temperature for various energy- and momentum-dissipation mechanisms. The nature of these functions differs from that in the equilibrium case, in that there is an additional dispersion, whose frequency dependence may be nonmonotonic. In a piezoelectric semiconductor, in the case of momentum dissipation at ionized impurities, there exists acritical field at which the spectral functions for the fluctuations in the current and electron temperature become infinite, due tothe appearance of a superheating instability.

Show AbstractMoscow University Physics Bulletin 1971. N 1.

A ferromagnetic-resonance study was made of the magnetic-anisotropy constant of the polycrystal ferrite spinels CoxNi0_s_r/2 Cu0ib_xl2 Fe204 (x = 0.00, 0.02, 0.04, 0.06 and 0,08). Quenching from a high temperature (950°C) leads to an increase in the positive constant К due to the transfer of arelatively small number of A ferromagnetic-resonance study was made of the magnetic-anisotropy constant of the polycrystal ferrite spinels CoxNi(0,5—x/2) Сu(0,5—x/2) Fe2O4(х=0,00; 0,02; 0,04; 0,06; 0,08). Quenching from a high temperature (950°C) leads to an increase in the positive constant К due to the transfer of arelatively small number of Ni^{2+}ions to the tetrahedral sublattice. The results agree with the data of Pointon, who studied the effect for nickel ferrites containing a slight amount of Co. ions to the tetrahedral sublattice. The results agree with the data of Pointon, who studied the effect for nickel ferrites containing a slight amount of Co.

Show AbstractMoscow University Physics Bulletin 1971. **26**. N 1. P. 37

Various methods are analyzed for solving the problem of the vibration of a sphere or cylinder immersed in a liquid caused by a plane sound wave having a velocity amplitude Vq. The amplitude and phase of the velocity v(a) are found as functions of the wave parameter а = ka = 2πa/λ, where a is the radius of the sphere (or cylinder). The theoretical results were checked experimentally up to а = 2,5 (а≈0,4 λ).

Show AbstractMoscow University Physics Bulletin 1971. **26**. N 1. P. 45

The energy of the lowest-lying state of an exciton in a crystal not having a symmetry center is calculated in the two-band effective-mass approximation. A modified variational method is used.

Show AbstractMoscow University Physics Bulletin 1971. **26**. N 1. P. 48

The positions and widths of several of the low-lying single and triple S(+), Р(-) and D(+)resonances are calculated in the diagonalization approximation for all the helium-like ions from Li+ to the tetravalent carbon ion. The results are compared with available experimental and theoretical data.

Show AbstractMoscow University Physics Bulletin 1971. **26**. N 1. P. 54

An analysis is made of the effect of the phonon-phonon interaction at T = 0°K on the intrinsic energy of the phonon in the cubic approximation. The renormalized spectrum of ("dressed") phonons is found to be stable, as Landau and Khalatnikov concluded from a calculation of the viscosity of liquid helium.

Show AbstractMoscow University Physics Bulletin 1971. **26**. N 1. P. 59

A method is proposed for writing abbreviated equations for oscillatory systems containing nonlinear elements whose characteristics are approximated by segments of curves. The method is based on a search for the approximate points at which the discontinuities occur.

Show AbstractMoscow University Physics Bulletin 1971. **26**. N 1. P. 62

A method is described for evaluating various parameters of a linear system in terms of their effect on stability of the system.

Show AbstractMoscow University Physics Bulletin 1971. N 1.

The contributions from second-order atomic Feynman diagrams with four external lines are given. A summation is carried out over the angular-momentum projections. The corresponding fractional parentage coefficients are determined. The contributions are expressed in terms of radial integrals.

Show AbstractB r i e f r e p o r t s

Moscow University Physics Bulletin 1971. **26**. N 1. P. 72

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