Динамические модели и реконструкции ЭКГ при гелиогеофизических флуктуациях

Clause is devoted to consideration of theoretical models of adaptable modes of generation and stability of heart, as nonlinear dynamic dot source. Consideration is limited by research of time dynamics of an electrocardiogram. The comparative description of corresponding mathematical dynamic models available on today is lead. Necessity of creation of as much as possible general model which are based physical laws of processes of the response of heart on external influence is revealed.Настоящая работа посвящена рассмотрению теоретических моделей адаптационных режимов генерации и устойчивости сердца, как нелинейного динамического точечного источника. В статье показано, что малые возмущения динамической системы в фазовом пространстве имеют собственные моды с наибольшими показателями роста в окрестностях особых точек, две из которых находятся в интервале T и Р-зубцов. Таким образом, качественное поведение системы и ее вариабельность при внешнем воздействии определяются эволюционными свойствами этих интервалов

The alpha-effect and current helicity for fast sheared rotators

We explore the alpha-effect and the small-scale current helicity, for the case of weakly compressible magnetically driven turbulence that is subjected to the differential rotation. No restriction is applied to the amplitude of angular velocity, i.e., the derivations presented are valid for an arbitrary Coriolis number, though the differential rotation itself is assumed to be weak. The expressions obtained are used to explore the possible distributions of alpha-effect and current helicity in convection zones (CZ) of the solar-type stars. The implications of the obtained results to the mean-field dynamo models are discussed.Comment: 20 pages, 6 figure

Active region formation through the negative effective magnetic pressure instability

The negative effective magnetic pressure instability operates on scales encompassing many turbulent eddies and is here discussed in connection with the formation of active regions near the surface layers of the Sun. This instability is related to the negative contribution of turbulence to the mean magnetic pressure that causes the formation of large-scale magnetic structures. For an isothermal layer, direct numerical simulations and mean-field simulations of this phenomenon are shown to agree in many details in that their onset occurs at the same depth. This depth increases with increasing field strength, such that the maximum growth rate of this instability is independent of the field strength, provided the magnetic structures are fully contained within the domain. A linear stability analysis is shown to support this finding. The instability also leads to a redistribution of turbulent intensity and gas pressure that could provide direct observational signatures.Comment: 19 pages, 10 figures, submitted to Solar Physic

Models of reactions of human heart as nonlinear dynamic system to cosmic and geophysical factors

The paper analyzes theoretical models of the adaptive modes of generation and stability of human heart as a nonlinear point source. The analysis encompasses only ECG time-domain dynamics. To solve the general problem of the study of the adaptive changes of the cardiosignal under the action of external periodic force and parametric noise, a new dynamic model is proposed, which incorporates two control physical parameters: power of signal generation and coefficient of diffuse signal scattering. For the entire set of parameters, the examined modeled nonlinear system demonstrated a number of various performance modes ranging from steady-state periodic and quasi-periodic states to chaos. The model showed that variations in cosmic, geophysical, and weather conditions in the frequency range of 0.1-0.9 Hz produce the greatest biotropic influence. © 2010 Springer Science+Business Media, Inc

Solar torsional oscillations as due to the magnetic quenching of the Reynolds stress

. The solar torsional oscillations are considered as the response of the Reynolds stress to the timedependent dynamo-induced magnetic field. This picture is opposite to the so far accepted idea that it is the largescale Lorentz force which directly drives the temporal variations of the surface rotation profile. Here, the "magnetic quenching" of the components of the Reynolds stress -- viscosity tensor and-effect -- is the basic reason for the cyclic rotation law. In order to produce the suppressing magnetic field it was necessary to construct a turbulent dynamo. Its site is the overshoot region, with the ff-effect existing only in an equatorial domain. The produced butterfly diagram is shown in Fig. 5. Mainly the toroidal field quenches the turbulent Reynolds stress deep in the convection zone. For a simplified model we find indeed that an observable flow pattern of 1--2 m/s appears with the correct frequency at the solar surface. The pattern can be interpreted as a wave originating at..

A Helicity Proxy From Horizontal Flow Patterns

. Motivated by new observations of solar surface flow patterns of mesogranulation, theoretical computations of the horizontal divergence-vorticity correlation are presented. Because of its close relation to the helicity in rotating turbulence such observations and discussions are of particular importance for the conventional dynamo theory. For the northern hemisphere we find a small, but always negative, divergence-vorticity correlation. Both an analytical Second Order Correlation Approximation for slow rotation as well as a numerical simulation (originally done for accretion disks) for fast rotation yield very similar results. Key words: Mesogranulation, turbulence, dynamo theory 1. Introduction Modern stellar physics considers solar/stellar activity as being driven by a dynamo mechanism maintaining a large-scale magnetic field. The dynamo itself is thought to result from the interaction between turbulence and rotation, the latter modifying the turbulence structure. Non-local theori..

Models of reactions of human heart as nonlinear dynamic system to cosmic and geophysical factors

The paper analyzes theoretical models of the adaptive modes of generation and stability of human heart as a nonlinear point source. The analysis encompasses only ECG time-domain dynamics. To solve the general problem of the study of the adaptive changes of the cardiosignal under the action of external periodic force and parametric noise, a new dynamic model is proposed, which incorporates two control physical parameters: power of signal generation and coefficient of diffuse signal scattering. For the entire set of parameters, the examined modeled nonlinear system demonstrated a number of various performance modes ranging from steady-state periodic and quasi-periodic states to chaos. The model showed that variations in cosmic, geophysical, and weather conditions in the frequency range of 0.1-0.9 Hz produce the greatest biotropic influence. © 2010 Springer Science+Business Media, Inc

Viscosity-alpha and dynamo-alpha for magnetic-driven turbulence in density-stratified Kepler disks. Angular momentum transport and alpha-effect in Kepler disks

For a given isotropic and homogeneous field of magnetic fluctuations both the viscosity-alpha as well as the dynamo-alpha have been computed for accretion disks on the basis of a quasilinear approximation with shear flow and magnetic buoyancy included. The resulting viscosity-alpha proves to be positive for sufficiently strong shear (i.e. the angular momentum transport is outwards) while the sign of the dynamo-alpha depends on the hemisphere. Again, for sufficiently strong shear it changes its sign, it is now negative for the upper disk plane and positive for the lower one. Also the current helicity <j' x B'> changes its sign for increasing shear. For a Kepler flow in the upper (lower) disk plane it is positive (negative). In our turbulence model the current helicity of the fluctuations and the alpha-effect of dynamo theory are almost always out of phase, the signs of all the quantities are in perfect correspondence to numerical simulations of Brandenburg (1998, 2000). The kinetic helicity has the same sign as the alpha-effect - not, as often assumed, the opposite one. The resulting relation between the dynamo-alpha and the viscosity-alpha reveals the dynamo-alpha amplitude as rather small compared with the turbulence intensity. This is in contrast to earlier SOCA-results but again it is in confirmation with recent results of numerical simulations. (orig.)Also published in 'Proc. of IAU symp. 200 - The formation of binary stars', edited by H. Zinnecker and R. MathieuAvailable from TIB Hannover: RR 7310(2000-21/22) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman