Volume 30, Issue 3

A mathematical model of the dynamics of the Black and the Azov Seas is considered taking into account tide-generating forces. The problem of variational assimilation of sea surface temperature (SST) data is formulated and studied. Based on variational assimilation of satellite altimetry data, we propose an algorithm for solving the inverse problem of reconstruction of potential forces affecting the formation of the mean level and present a method of approximate solution of this problem.We also present numerical experiments concerning the study of the influence of tide-generating forces on the dynamics of the Black Sea and restoration of the heat flux function in the problem of variational data assimilation of SST observations

A joint three-dimensional numerical model of formation of convective clouds in the atmosphere is constructed with a detailed description of microphysical processes. A transport model of multicomponent gaseous admixtures and aerosols is also a constructed subject to gas-phase and liquid-phase chemical reactions. Basic physical mechanisms of formation of liquid droplet clouds of medium size and the transport of gases with different reactivity and solubility are considered. The calculations performed with the use of the data on emission of NO x , SO 2 , and other components in Moscow and the information related to location of their sources allowed us to get a picture of the distribution of acidity and salinity in precipitation around the city, which appeared to be consistent with monitoring data. Numerical values of concentrations of ionic components in precipitation indicate their local origin and are sufficiently close to monitoring data taking into account the uncertainty in the emission data. The evidence that the source of chloride anions in precipitation in Moscow are components of anti-icing agents (AIA) is found

The aim of this work is the construction, calibration, and comparative analysis of mathematical models of the evolution of the human immunodeficiency virus (HIV) in the course of infection when the models are based on deterministic principles of the quasispecies theory (Eigen-Schuster) and on stochastic approaches of genetic algorithms (Holland). The models take into account the replication of viral genomes and selection of descendants according to their fitness, point mutations, multi-infection of target cells and recombination of genomes at the stage of formation of proviral DNA. The processes of diversification of the virus population under the action of the antiviral drug azidothymidine (AZT) that blocks reverse transcription of the virus are simulated. A four-letter alphabet is used in the stochasticmodel for description of nucleotide sequences. The parameters of the model are estimated using original data on the degree of adaptation of the HIV mutants that are partly or completely resistant to this drug. The influence of parameters of infection on the characteristics of viral mutants population diversity is studied

The paper is aimed to construction of models of mechanisms determining the accuracy and stability of maintenance of target values for internal environment characteristics. The organism is described as an integrated set of physiological systems, namely, the homeostasis maintaining system, the reproductive system, and others. Those systems are joined by a common internal environment and a pool of energy substrate. The accuracy of homeostasis maintenance depends on the power, and the resistance to strong perturbations depends on the functional reserve of the homeostasis maintaining system. A specific feature of the model is the consideration of the dependence of the violation of internal environment characteristics on the current power of the energy metabolism. Experimental data show that the energy cost of maintaining the homeostasis and regeneration exceeds 70% of total energy expenditure of the body and creates most of the load of the system. The energy cost of homeostasis maintenance increases with the growth of the functional reserve and/or the deviation of internal environment characteristics from their target values, which reduces the amount of energy used for regeneration and reproduction. The model describes a physiologically motivated algorithm of adaptive use of functional reserves and energy substrate

Patient-specific simulations of human physiological processes remain the challenge for many years. Detailed 3D reconstruction of body anatomical parts on the basis of medical images is an important stage of individualized simulations in physiology. In this paper we present and develop the methods and algorithms for construction of patient-specific discrete geometric models. These models are represented by anatomically correct computational meshes. Practical use of these methods is demonstrated for two important medical applications: numerical evaluation of fractional flow reserve in coronary arteries and electrocardiography simulation