Solutions of the BBGKI equations in the fourth approximation in the temperature

Solutions of the Bogolyubov-Born-Green-Kirkwood-Ivon equations in the fourth approximation in the temperature are given in a class of generalized functions both for van der Waals and ionic crystals in the case of the so-called taking into account of smoothed correlations. A statistical thermodynamics of strongly anharmonic van der Waals and ionic crystals is constructed. Temperature expansions of the correlative distribution functions and thermodynamic quantities are investigated within the framework of the indicated method. The temperature dependence of cubic order is taken into account in the expression of the isochoric specific heat and the Grüneisen parameter of the listed crystals. It is shown that the temperature expansion for the isochoric specific heat of anharmonic crystals converges well for a value of the reduced temperature 0.33 T_m (T_m is the melting temperature).Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 55–59, July, 1981.     

在稳定中求变在变化中求新——2010年高考浙江省理综(物理)试题评析

1 总体特征 通读2010年高考浙江省理综卷物理试题,给人以耳目一新的感觉.命题者在2010年的命题设计中,做到了三个贴近,即贴近时代、贴近生活、贴近学生.实现了三个有利的原则,即"有利于高等学校选拔新生,有利于中学推行素质教育,有利于激发考生学习科学的兴趣".     

Role of the near-electrode regions in the formation of the volume discharge heterogeneity in nitrogen in the pin-to-plane configuration

The development of streamers and sparks in nitrogen at atmospheric pressure in the pin-to-plane electrode configuration is studied in experiments and theoretical calculations. It is demonstrated that the near-electrode regions play the decisive role in streamer initiation. At a negative pin voltage, a spark is formed in the absence of fast primary streamers. At a positive pin voltage, streamer build-up is initiated by the current spots on the anode that result from the development of the ionization instabilities in the anode region. The calculations show that the formation of the current spot on the anode leads to a redistribution of the electric field in the vicinity of the anode, so that a single avalanche is transformed into a streamer under the conditions when the known criterion for streamer breakdown (the Meek-Raether criterion) is not satisfied. Original Text ? Astro, Ltd., 2006.     

Superconductivity in the t-J model in the large-N limit

Using a 1/N expansion for X-operators the leading contributions to the linearized equation for the superconducting gap of the t-J model are derived and the gap equation solved numerically on a square lattice. We find a strong instability towards superconductivity only in the d-wave (T ₃) channel with T _c/│t│ ～ 0:01 where T _c is the transition temperature and t the nearest-neighbor hopping integral. The underlying effective interaction consists of an attractive, instantaneous term with the band width, and a retarded term due to charge and spin fluctuations with ～ J, as energy scale.     

Change in the sign of the magnetoresistance effect in bilayer superconductor/ferromagnet structures under change in the type of the domain structure in the ferromagnet

The magnetoresistance effects in the bi- and trilayer hybrid planar superconductor/ferromagnet (S/F) structures based on Py (permalloy) and Nb near the superconducting transition temperature T _C are considered. It has been experimentally shown that the sign of the observed magnetoresistance peaks in the bilayer S/F systems changes from negative to positive at the permalloy layer thickness corresponding to the change in the type of domain walls from Néel to Bloch. For the Néel walls at the ferromagnet coercive fields, the negative magnetoresistance effect, which is due to a decrease in the depairing action of the exchange field E _ex, is observed in the S/F bilayers. For the Bloch domain walls, the magnetoresistance of the bilayer S/F structures is determined by the dissipative motion of Abrikosov vortices in the superconducting layer. In the trilayer F/S/F structures, the magnetoresistance is mainly due to the suppression of the superconducting order parameter in the superconducting layer under the action of the accumulation of the spin-polarized carriers near the S/F interfaces.     

Absorption in the final state in reactions and decays in the medium

The role of strong absorption of particles in intermediate and final states has been considered. The range of applicability of phenomenological models of absorption has been studied. This model is nonuniversal. Its applicability depends on the type of interaction Hamiltonian and matrix element used. We also demonstrate that the violation of the unitarity condition can produce a qualitative error in the results. The absorption (decay) in the final state does not tend to suppress the total process probability as well as the probability of the channel corresponding to absorption. This is true for the reactions, decays and nˉ conversion in the medium.     

Correlation between Variations in the Number of Neutrons in the Atmosphere and in the Intensities of the Atmospheric Ozone Lines

We compare the data on the atmospheric radio emission in two ozone lines with resonance frequencies 96,228 and 101,736 MHz, obtained at the N. I. Lobachevsky State University of Nizhny Novgorod in 1996–2001, with the corresponding results of measuring the number of neutrons in the atmosphere, obtained at the Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation (Troitsk, Moscow region) using the NM-64 monitor. It is shown that variations in both the optical depth and the intensity ratio of these lines correlate with variations in the number of neutrons. The maximum observed correlation coefficients for the optical-depth decrements of the lines amount to 0.5–0.6, which is about a factor of 1.5 higher than the maximum correlation coefficient for their intensity ratio. We analyze the dependence of the correlation coefficients on the time shift between data series for the ozone line intensity and the number of neutrons in the atmosphere. It is shown that correlation between these data series almost vanishes for a time shift of about 200 h. We discuss the features of the data on the number of neutrons in the atmosphere and the possibility of the solar origin of neutrons.     

Strong coupling in the Kondo problem in the low-temperature region

The magnetic field dependence of the average spin of a localized electron coupled to conduction electrons with an antiferromangetic exchange interaction is found for the ground state. In the magnetic field range μH∼0.5T _c (T _c is the Kondo temperature) there is an inflection point, and in the strong magnetic field range μH≫T _c , the correction to the average spin is proportional to (T _c /μ H)². In zero magnetic field, the interaction with conduction electrons also leads to the splitting of doubly degenerate spin impurity states. Zh. éksp. Teor. Fiz. 115, 1263–1284 (April 1999) Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor     

Metastates in the Hopfield Model in the Replica Symmetric Regime

We study the finite dimensional marginals of the Gibbs measure in the Hopfield model at low temperature when the number of patterns, M, is proportional to the volume with a sufficiently small proportionality constant > 0. It is shown that even when a single pattern is selected (by a magnetic field or by conditioning), the marginals do not converge almost surely, but only in law. The corresponding limiting law is constructed explicitly. We fit our result in the recently proposed language of metastates which we discuss some length. As a byproduct, in a certain regime of the parameters and (the inverse temperature), we also give a simple proof of Talagrands recent result that the replica symmetric solution found by Amit, Gutfreund, and Sompolinsky can be rigorously justified.