bifurcations

Topic. A review of the basic dynamical models of neural activity is presented and individual features of their behavior are discussed, which can be used as a basis for the subsequent development and construction of various configurations of neural networks. The work contains both new original results and generalization of already known ones published earlier in different journals.

Aim. The aim of the work is to study the scientific heritage of A.M. Lyapunov from the standpoint of nonlinear physics. Fundamental importance Lyapunov’s contribution is determined not only by the methods he created, which became the basis of the mathematical apparatus in the study of nonlinear phenomena, but his ideas and concepts introduced by him contributed to the formation of concepts and principles of nonlinear dynamics. Method.

In the proposed paper, we investigate the dynamical behavior of the modified system with frequency-phase control, which uses two-channel discriminator in the circuit of phase control and multi-frequency discriminator with periodic nonlinearity in the circuit of frequency control. We consider the case of identical low-pass filters of the third order in the both control circuits.

The work is dedicated to the history of the theory of nonlinear integral equations, covering a period before the start of the 1930s. By analyzing the specifics of the initial period, authors emphasize that the integral equations (in particular, nonlinear equations) is independent object of research with their own problems, requiring its own system of concepts and own language. As a starting point here A.M.

In this paper we study the bifurcational mechanisms of synchronization and multistability formation in a system of two interacting van der Pol oscillators, one of which is under external harmonic forcing. We draw a two­parametric bifurcation diagram for phasereduced system and study its evolution in transition from symmetrical to asymmetrical repulsive interaction. Relying on the results of bifurcation analysis of non­reduced system we conclude that the synchronization scenarios found in the phase­reduced system correspond to the ones in the non­reduced system.

The condition of a bifurcation of a round­trip time of ultrashort pulses (USP) in the Nd­laser with short­time resonant modulation of loss is found out experimentally. This condition is exhibited in the period doubling in the area of a small detunings of the modulation frequency and an intermodal interval. It is revealed, that the pumping level (amplification in the active medium) is a major factor, influencing this effect.

We study the process of competition in the two­component model of the immune T­cells ensemble that underpins the selection mechanism of the most efficient T­cell species (clonotypes). We demonstrate the absence of periodic oscillations, determine the regions of coexistence, partial and mutual extinction of clonotypes. Applicability of the mean field approximation is analyzed. The biological implications of the results are discussed.

In this paper we research a mathematical model of dynamics for the population number. We considered the population of the two­age classes by the beginning of the next season: the younger, one including not reproductive individuals, and the senior class, consisting of the individuals participating in reproduction. The model parameters (birth rate and survival rates) represent the exponential functions of the both age groups numbers. According to this supposition the density­dependent factors restrict the development of population.