Simple measure of memory for dynamical processes described by a generalized Langevin equation.

Memory effects are a key feature in the description of the dynamical systems governed by the generalized Langevin equation, which presents an exact reformulation of the equation of motion. A simple measure for the estimation of memory effects is introduced within the framework of this description. Numerical calculations of the suggested measure and the analysis of memory effects are also applied for various model physical systems as well as for the phenomena of "long time tails" and anomalous diffusion.

Pumping action of the heart in rat pups subjected to muscle training at different terms of postnatal ontogeny.

Experiments performed on random-bred rat pups showed that muscle training during earlier terms of postnatal ontogeny produce more pronounced changes in the pumping function of the heart.

Age-related differences in the response of blood stroke volume to stimulation of the sympathetic ganglion in rats with beta-adrenoceptor blockade.

Blood stroke volume in rats aging 21 and 56 days decreased during beta-adrenoceptor blockade with propranolol, but increased again by the 15th minute after treatment. Suprathreshold stimulation of the stellate ganglion decreased the stroke volume and increased the heart rate in control animals. Electrical stimulation after beta-adrenoceptor blockade was followed by a further decrease in stroke volume in young rats.

Relaxation time scales in collective dynamics of liquid alkali metals.

In this paper the investigation of the dynamical processes of liquid alkali metals is executed by analyzing the time scales of relaxation processes in liquids. The obtained theoretical dynamic structure factor S(k,omega) for the case of liquid lithium is found to be in excellent agreement with the recently received inelastic x-ray scattering data. The comparison and interrelation with other theories are given here.

Stimulation of vagus nerve modifies negative chronotropic and hypotensive effects of adenosine.

The effects of electrical stimulation of the vagus nerve on the negative chronotropic and hypotensive effects of adenosine were studied on adult rats. Intravenous injection of adenosine to control rats significantly reduced the heart rate and induced a transient blood pressure drop followed its increase. Preliminary electrical stimulation of the right vagus nerve reduced the magnitude and duration of adenosine-induced bradycardia and changed the dynamics of adenosine-induced arterial pressure perturbations.

Diffusion time-scale invariance, randomization processes, and memory effects in Lennard-Jones liquids.

We report the results of calculation of diffusion coefficients for Lennard-Jones liquids, based on the idea of time-scale invariance of relaxation processes in liquids. The results were compared with the molecular dynamics data for the Lennard-Jones system and a good agreement of our theory with these data over a wide range of densities and temperatures was obtained. By calculations of the non-Markovity parameter we have numerically estimated statistical memory effects of diffusion in detail.

Effect of beta-adrenoceptor blockade on cardiac activity in rats during postnatal ontogeny.

Electrical stimulation of the right stellate ganglion produces a positive chronotropic effect in 21-, 56-, and 100-day-old rats. The response of the heart rate to suprathreshold stimulation increased from the 21st to 100th day. By contrast, during beta-adrenoceptor blockade the heart rate response decreased.

Blockade of hyperpolarization-activated channels modifies the effect of beta-adrenoceptor stimulation.

Experiments on rats showed that blockade of hyperpolarization-activated currents moderates tachycardia induced by beta-adrenoceptor agonist isoproterenol and potentiates the increase in stroke volume produced by this agonist. Electrical stimulation of the vagus nerve against the background of isoproterenol treatment augmented bradycardia and increased stroke volume. Blockade of hyperpolarization-activated currents followed by application of isoproterenol moderated vagus-induced bradycardia and had no effect on the dynamics of stroke volume.

Effect of electrical stimulation of right stellate ganglion on cardiac function in rats during postnatal ontogeny.

In all examined age groups of rats, the threshold amplitude of stellate ganglion stimulation is higher for the positive chronotropic effect than for the inotropic effect. The stimulation produced a more pronounced effect on stroke volume than on heart rate.

Quantification of heart rate variability by discrete nonstationary non-Markov stochastic processes.

We develop the statistical theory of discrete nonstationary non-Markov random processes in complex systems. The objective of this paper is to find the chain of finite-difference non-Markov kinetic equations for time correlation functions (TCF) in terms of nonstationary effects. The developed theory starts from careful analysis of time correlation through nonstationary dynamics of vectors of initial and final states and nonstationary normalized TCF.

Possibility between earthquake and explosion seismogram differentiation by discrete stochastic non-Markov processes and local Hurst exponent analysis.

The basic scientific point of this paper is to draw the attention of researchers to new possibilities of differentiation of similar signals having different nature. One example of such kinds of signals is presented by seismograms containing recordings of earthquakes (EQ's) and technogenic explosions (TE's). EQ's are among the most dramatic phenomena in nature.

Time-scale invariance of relaxation processes of density fluctuation in slow neutron scattering in liquid cesium.

The realization of the idea of time-scale invariance for relaxation processes in liquids has been performed by the memory functions formalism. The best agreement with experimental data for the dynamic structure factor S(k,omega) of liquid cesium near melting point in the range of wave vectors (0.4 A(-1) < or = k < or = 2.

A new insight into mechanisms of age-related changes in heart rate.

Changes in cardiac rhythm induced by blockade of hyperpolarization currents with ZD 7288 depend on animal's age. The increase in cardiointerval duration is related to prolongation of T-P segment on ECG. It is hypothesized that the age-related changes in activity of hyperpolarization channels are determined by a modulating effect of the autonomic nervous system.

Blockade of hyperpolarizing currents produces a dose-dependent effect on heart rate.

Intravenous injection of ZD 7288, a new specific hyperpolarizing current blocker, dose-dependently reduces heart rate in adult rats. The autonomic nervous system modulates changes in heart rate caused by hyperpolarizing currents.

Asymmetrical effects of vagus nerves on functional parameters of rat heart in postnatal ontogeny.

Significant age-related peculiarities in the dynamics of stroke volume and parameters of variational pulsogram are revealed in bilaterally vagotomized in rats. Asymmetry in vagal influences on cardiac function appear during puberty. Right-sided vagotomy predominantly affects variability of the cardiac rhythm, while left-sided vagotomy mostly affects the force of heart contractions.

Stochastic dynamics of time correlation in complex systems with discrete time.

In this paper we present the concept of description of random processes in complex systems with discrete time. It involves the description of kinetics of discrete processes by means of the chain of finite-difference non-Markov equations for time correlation functions (TCFs). We have introduced the dynamic (time dependent) information Shannon entropy S(i)(t) where i=0,1,2,3,ellipsis, as an information measure of stochastic dynamics of time correlation (i=0) and time memory (i=1,2,3,ellipsis).

Regulation of cardiac function in prepubertal rats.

Prepubertal period in rats is characterized by some peculiarities of the cardiac regulatory mechanisms. In 6-week-old rats atropine produced bradycardia instead of tachycardia. Similar reaction was not observed in chemically sympathectomized age-matched rats.