Multi-species model of interacting biological populations of shallow water

Paper covers research of biological processes kinetics based on a multi-species model of plankton and fish interaction of the Azov Sea at low and high size considering the Verhulst and Allee effects, competition for resources, taxis, catching, spatial distribution of biogenic matter and detritus. Discrete analogue of developed model problem of water ecology, included in a software complex, were calculated using schemes of increased order of accuracy considering the partial filling of computational cells. The system of grid equations of large dimension, arising at discretization, has been solved on the basis of a two-layer variational type method – the minimum corrections method having the maximum convergence rate. Effective parallel algorithms were developed for numerical implementation of biological kinetics problem and oriented on multiprocessor computer system and NVIDIA Tesla K80 graphics accelerator with the data storage format modification of. Due to it, the reproduction processes of biogeocenose populations have been analysed in real and accelerated time.The reported study was funded by RFBR according to the research project № 19-07-00623

Research the phytoplankton dynamics regimes depending on nutrient transformation processes in coastal systems

The paper describes the construction of a three-dimensional mathematical model of biogeochemical processes, considering the salinity and temperature influence on the phytoplankton populations’ development. The paper proposes a new difference scheme for solving convection-diffusion-reaction problems at large values of the Peclet grid number (2<Pe≤20), which is a linear combination of the central and the upwind leapfrog difference schemes. The three-layer difference scheme is more accurate than the traditional upwind leapfrog difference scheme for problems where convection prevails over diffusion. The construction of discrete equations for solving the problem of biogeochemical cycles on the basis of the scheme considering the filling of cells is described. The stationary regimes of phytoplankton dynamics problem were researched considering the transformation of phosphorus, nitrogen and silicon forms. Results of software complex, which allows to simulate biogeochemical processes in the Azov Sea, were described. The software package allows to forecast the dynamics of the Azov Sea ecosystem development in the conditions of modern salinization.The reported study was funded by RFBR, project number 20-01-00421

THE TRIPLE HELIX MODEL IN THE RUSSIAN ECONOMY: THE QUALITY EVALUATION OF NEW INSTITUTIONALIZATION

This article analyzes the transition of the national economy to the Triple Helix model. This model is considered as new institutionalization. The evaluation has been carried out using the modified method of evaluation of innovation diffusion. It has shown that the Russian economy and especially the national entrepreneurship need additional incentives to direct economic, as well as social, sectors to the innovation-based development. The article clarifies the econometric methodology for assessing the rate of diffusion of innovations in national economies (the Rogers's model), which made it possible to study the dynamics of the development of the Russian economy from this point of view. The obtained data suggest that a qualitatively new economy based on the triple helix model by H. Etzkowitz has not yet been formed in Russia, which explains the current stagnation. The innovation reserve available in the Russian economy can be used for a technological breakthrough, but this will require new economic reforms

Features of management and factors of economic stability of an industrial enterprise in the region

The article explores the peculiarities of economic stability of enterprises, gives a brief description of this concept. The economic sustainability of an individual enterprise is being updated for the economic sustainability and competitiveness of the meso-economic system. There is a need to differentiate the concepts of sustainability and balance. Factors of influence on economic stability of the enterprise are considered. The need to manage economic sustainability is argued

Gamma-radiation from the accretion of supernova envelope on compact remnant

Abstract: The numerical simulation of massive envelope of a star during supernova type II explosion with the compact object was done. The characteristic time when the envelope becomes transparent and the supernova remnant can be observed in gamma rays was estimated. The parameters of the supernova were chosen to correspond to observable characteristics of SN 1987A.Note: Research direction:Mathematical modelling in actual problems of science and technic

COVID-19 risk factors for mortality in hospitalized patients: results of a retrospective study

Objective. To identify risk factors for fatal outcome and COVID-19-associated liver damage in hospitalized adult patients with coronavirus infection. Materials and Methods. In a retrospective cohort study, 389 cases of patients with coronavirus infection complicated by bilateral viral pneumonia were studied. Demographic characteristics, clinical features of the course of the disease, anamnestic data, results of laboratory and instrumental methods of examination were analyzed and correlated with mortality. At the time of admission, the following were taken into account: fever, severity of the patient's condition according to COVID-19 classification of severity, body mass index (BMI), oxygen saturation (SpO2), percentage of lung tissue damage according to computed tomography (CT). Laboratory indices of biochemical blood analysis were assessed in dynamics: alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin, total protein, albumin, C-reactive protein (CRP). Data analysis was performed using the R programming language (ver. 4.1.1.). Results. The following risk factors, assessed at the time of hospitalization, increased the likelihood of death: severe and extremely severe condition of the patient (RR = 4.77; 95% CI: 3.33–6.83); SpO2 less than 93% (RR = 3.76; 95% CI: 2.57–5.49); diabetes mellitus (RR = 2.94; 95% CI: 2.01–4.30); lung tissue damage CT-3 and CT-4 (RR = 2.66; 95% CI: 1.79–3.75); concomitant chronic pyelonephritis and chronic kidney disease (CKD) (RR = 2.59; 95% CI: 1.79–3.74); age 65 years and older (RR = 2.50; 95% CI: 1.70–3.67); ischemic heart disease (IHD) (RR = 2.39; 95% CI: 1.42–4.01); an increase in the level of CRP more than 15 mg/l (RR = 2.22; 95% CI: 1.16–4.24); BMI 35 kg/m2 or more (RR = 1.89; 95% CI: 1.28–2.77); AST level more than 2 upper limit of normal (ULN) (RR = 1.75; 95% CI: 1.20–2.55). Risk factors for an increase in AST more than 2 ULN were: SpO2 less than 93% (RR = 1.53; 95% CI: 1.15– 2.03), severe and extremely severe course of coronavirus infection (RR = 1.83; 95% CI: 1.38–2.43), concomitant chronic liver disease (RR = 1.45, 95% CI: 1.08–1.95). Conclusions. Risk factors for fatal COVID-19 in hospitalized patients are: severe and extremely severe initial condition of the patient, oxygen saturation less than 93%, lung tissue damage more than 50%, age older than 65 years, presence of concomitant diabetes mellitus, chronic pyelonephritis and CHD, CHD, obesity, increased CRP level more than 15 mg/l, and AST more than 70 units/l. Elevation of AST over 2 IU/L can be considered as one of the prognostic laboratory markers of adverse prognosis COVID-19