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Biomedical subjects

A V Karnaukhov

Publications and source records attributed to A V Karnaukhov.

16 recordsLinked to original sources
PubMed2003

Application of a new method of nonlinear dynamical system identification to biochemical problems.

The system identification method for a variety of nonlinear dynamic models is elaborated. The problem of identification of an original nonlinear model presented as a system of ordinary differential equations in the Cauchy explicit form with a polynomial right part reduces to the solution of the system of linear equations for the constants of the dynamical model. In other words, to construct an integral model of the complex system (phenomenon), it is enough to collect some data array characterizing the time-course of dynamical parameters of the system. Collection of such a data array has always been a problem. However difficulties emerging are, as a rule, not principal and may be overcome almost without exception. The potentialities of the method under discussion are demonstrated by the example of the test problem of multiparametric nonlinear oscillator identification. The identification method proposed may be applied to the study of different biological systems and in particular the enzyme kinetics of complex biochemical reactions.

Enzymes↗
PubMedDate not supplied

[Role of biodiversity in maintaining Earth;s climate and and human civilization. Problems of geobiophysics].

Factors affecting the concentration of CO2 in atmosphere were analyzed, and the conditions providing the Earth termal balance stability were considered. It was shown that the antropogenic decrease of biodiversity in climate-forming biosystems, such as swamps and tropical seas, may lead to the greenhouse disaster, resulting in the raise of the temperature on the Earth's surface up to 300 degrees C and elimination of Life on Earth. By the example of the ecological disaster caused by the introduction of the European mollusc Dreissena into fresh waters of the North America, which was predicted by us, it was shown that the main reason for the decrease in biodiversity, which can accelerate the greenhouse disaster, is the violation of one of the Darvin principles of species formation, the principle of geographical isolation of species. It is shown in terms of a new model of periodical glaciation of the Northern Hemisphere that the elevation of Earth surface temperature caused by an increase in CO2 concentration in the atmosphere can substantially accelerate the onset of a new glaciation period in the Northern Hemisphere, which may decrease the greenhouse disaster rate. The necessity of the formation of a new interdisciplinar scientific branch, geobiophysics, is considered.

Animals↗
PubMedDate not supplied

[Prospects in development of geobiophysics].

The results of the discussion about the problems of biodiversity and geobiophysics are summarised. The conclusion about the necessity of developing a new scientific branch that unites Life Sciences and Earth Sciences is drawn.

Biophysical Phenomena↗
PubMedDate not supplied

[The role of biosphere in the formation of the Earth climate. A greenhouse catastrophe].

The role of processes in organic and inorganic nature that determine the formation of the atmosphere chemical composition and Earth temperature balance was analyzed. It was concluded that the biological mechanisms of CO2 removal from the atmosphere are insufficient, and there exist potentially hazardous CO2 sources in inorganic nature that can be activated upon elevation of the mean Earth temperature. It was shown that the stability of natural systems of maintaining the constant chemical composition of the atmosphere is destroyed due to the disturbance by man of climate-forming biocenoses, which may lead to irreversible changes in Earth's climate with the result that the mean planetary temperature would be elevated to 100-150 degrees C and above. This would make impossible the existence of life on our planet, at least in its present form. A radiation-adiabatic model of the greenhouse effect was constructed in the framework of which asymptotic estimates of the increase in mean planet temperatures for a wide range of changes in the concentration of greenhouse gases were obtained. On the basis of the model, an integral model of changes in Earth's climate was constructed, which takes into account the heat inertia of the ocean and aerosol contaminations of the upper layers of the atmosphere. It was shown that irreversible (catastrophic) changes in Earth's climate (greenhouse catastrophe) may occur in a relatively near future (200-300 years).

Algorithms↗
PubMedDate not supplied

[Dissipative resonance. An analytical solution with fixed boundaries].

A simple one-dimensional model is presented in which the dissipative resonance phenomenon takes place. An analytical solution for steady-state oscillations occurring in the system due to the external periodic force was obtained. An analytical solution describing the dynamics of the particles-acceptors of the external force is also presented. Some common properties of such systems are considered. The method can be used to explore a wide class of models in which the dissipative resonance occurs and which can be used to describe the mechanisms of action of weak electromagnetic fields to biological and physiochemical objects.

Electromagnetic Fields↗
PubMedDate not supplied

[Microspectral studies of neuroendocrine regulation of gametogenesis in mollusks].

An associated culture of nervous ganglia and gonads was used to study the gametogenesis neuroendocrine regulation in mollusks (Mytilus edulis L.). The state of oocytes was controlled by microspectral fluorescent analysis on slides stained with acridine orange. The object of investigations was Mytilus edulis L. collected in La Manch in April-May. A microspectrofluorimetrical investigation of samples was carried out in Pushchino. As a criterion of cell synthetic activity, the parameter alpha was used. Parameter alpha is the ratio of fluorescence intensities in the red (I640) and green (I530) regions of the visible spectrum: alpha = I640/I530. The results obtained showed that the nervous system realized the endocrine regulation of gametogenesis in mollusks. There was no normal development of oocytes in an isolated mantle culture. The development of oocytes in a tissue culture proceeds in a similar manner as in the gonads of the native organism in normal natural conditions only if the mantle tissue is associated either with all nervous ganglia or with the cerebral ganglion alone. It was found that the cerebral ganglion plays a key role in the neuroendocrine regulation of gametogenesis.

Animals↗
PubMedDate not supplied

[A new method of identifying a systems based on the minimal quadratic discrepancy criterion for biophysics problems].

A wide range of biophysical systems are described by nonlinear dynamic models mathematically presented as a set of ordinary differential equations in the Cauchy explicit form: [formula: see text] Fij(X1(t),..,XN(t),t), (i = 1,...,N, j = 1,...,M), where Fij (X1(t), ..., XN(t), t) is a set of basis functions satisfying the Lipschitz condition. We investigate the problem of evaluation of model constants aij (the system identification) using experimental data about the time dependence of the dynamic parameters of the system Xi(t). A new method of system identification for the class of similar nonlinear dynamic models is proposed. It is shown that the problem of identifying an initial nonlinear model can be reduced to the solution of a system of linear equations for the matrix of the dynamic model constants [aj]i. It is proposed to determine the set of dynamic model constants aij using the criterion of minimal quadratic discrepancy for the time dependence of the set of dynamic parameters Xi(t). An important special case of the nonlinear model, the quadratic model, is considered. Test problems of identification using this method are presented for two nonlinear systems: the Van der Pol type multiparametric nonlinear oscillator and the strange attractor of Ressler, a widely known example of dynamic systems showing the stochastic behavior.

Algorithms↗
PubMedDate not supplied

[Changes in fluorescence spectral characteristics of blood nuclear cells by the action of physical factors associated with 11- and 22-year cyclic variations in solar activity].

A correlation between the functional (synthetic) activity of animal blood lymphocytes and the intensity of radiation of the Sun at a frequency of 2800 MHz in 2000 and 2002 was studied. The results were compared with the data obtained in 1993 and 1994. These data suggest that there are seasonal regularities in the interrelationship of the processes studied. A change in the sign of the correlation coefficients at the maximum of the 23rd solar cycle was shown. Possible mechanisms of the phenomena are discussed.

Animals↗
PubMedDate not supplied

[Consideration of a priori information and type of an experimental error using the method of system identification based on the minimal quadratic discrepancy criterion].

The variants of the identification method were considered that take the a priori information about the evolution of a system under study and the type of experimental errors of the dynamic parameters of the system into account. An example of using this method for the identification of a biochemical reaction is given where the error in measuring the dynamic parameters (concentration of substances) has both an absolute and a relative components.

Algorithms↗
PubMedDate not supplied

[Cause-effect modeling as a general method of description and study of phenomena in complex hierarchical systems].

The definition of the cause-effect model of a phenomenon and the rules of presenting these models in the form of cause-effect diagrams have been formulated. The relationship between cause-effect modeling and traditional methods of mathematical modeling has been analyzed. Examples of cause-effect models (diagrams) of phenomena of different physical nature are given, and the application of these models in studies of some problems is demonstrated. In particular, the mechanism of renormalizing the rate constans of chemical reactions in terms of dissipative resonance is considered. In addition, the renormalization of the climate sensitivity parameters and the relaxation time of the Earth climate system in terms of the two-component (CO2 + H2O) greenhouse effect is considered.

Ecology↗
PubMedDate not supplied

[Greenhouse catastrophe and the problem of developing human civilization].

Principal distinctions between the "greenhouse disaster" and traditional scenarios of mean global temperature increase on Earth caused by greenhouse effect are discussed. Processes accompanying "greenhouse disaster" are compared with actual climatic catastrophies of Carbon and Cretaceous. Different factors, such as underground nuclear explosions, are discussed in view of their influence on lithosphere stability and rate of mean global temperature increase.

Carbon Dioxide↗