Moscow University Physics Bulletin 

About: Moscow University Physics Bulletin is an academic journal published by Springer Science+Business Media. The journal publishes majorly in the area(s): Electron & Magnetic field. It has an ISSN identifier of 0027-1349. Over the lifetime, 1669 publications have been published receiving 4195 citations.

Shannon entropy in the research on stationary regimes and the evolution of complexity

Abstract: The questions of the identification of complex biological systems (complexity) as special self-organizing systems or systems of the third type first defined by W. Weaver in 1948 continue to be of interest. No reports on the evaluation of entropy for systems of the third type were found among the publications currently available to the authors. The present study addresses the parameters of muscle biopotentials recorded using surface interference electromyography and presents the results of calculation of the Shannon entropy, autocorrelation functions, and statistical distribution functions for electromyograms of subjects in different physiological states (rest and tension of muscles). The results do not allow for statistically reliable discrimination between the functional states of muscles. However, the data obtained by calculating electromyogram quasiatttractor parameters and matrices of paired comparisons of electromyogram samples (calculation of the number k of “coinciding” pairs among the electromyogram samples) provide an integral characteristic that allows the identification of substantial differences between the state of rest and the different states of functional activity. Modifications and implementation of new methods in combination with the novel methods of the theory of chaos and self-organization are obviously essential. The stochastic approach paradigm is not applicable to systems of the third type due to continuous and chaotic changes of the parameters of the state vector x(t) of an organism or the contrasting constancy of these parameters (in the case of entropy).

Cosmic Rays in the Earth's Atmosphere

Abstract: This paper presents a brief historical overview of studies of cosmic rays in the Earth’s atmosphere, which were initiated and led by S.N. Vernov for over 50 years. The main results of these studies that were obtained in recent decades are given. They include the study of the processes of generation and propagation of solar cosmic rays, the modulation of galactic cosmic rays in the heliomagnetosphere, and the role of cosmic rays in atmospheric processes.

Eigenwaves in a two-component system of particles with nonzero magnetic moments

Abstract: Two-component systems of particles with nonzero intrinsic magnetic moments are shown to support not only the transverse electromagnetic and longitudinal waves, but also self-consistent spin waves and waves that propagate independently in each component and degenerate into oscillations for spin-zero systems. For all types of waves, the dispersion relations are obtained by solving the quantum hydrodynamics equations and field equations in linear approximation.

The kinetic description of the accelerated-electron flux in solar flares

Abstract: We propose an accurate quantitative model describing the propagation of flare-accelerated electrons in the solar atmosphere. This model is based on a kinetic equation considering Coulomb collisions of accelerated electrons with thermal electrons and protons in the plasma of the solar corona and chromosphere. Using a self-consistent approach, we find the distribution function of accelerated electrons and the electric field of the reverse current balancing the electric current carried by the accelerated-electron flux. We compare our two-dimensional (in the velocity space) model with the widely used classical one-dimensional model that overlooks the reverse-current effect.

Influence of a constant magnetic field on the radiation of a planar undulator

Abstract: The influence of a constant magnetic field on the radiation of a planar undulator is studied analytically with the use of generalized Bessel functions. The behavior of on-axis radiation intensity in the undulator and the influence of a magnetic field on off-axis radiation are investigated. The critical magnitude of the constant component of the magnetic field, which has a significant effect on the motion of electrons in the undulator, is calculated analytically. The examples of several planar undulators are discussed, and the influence of the Earth’s magnetic field on their spectrum is evaluated.