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Transport of respiratory gases by respiratory and circulatory systems is one of the most important processes associated with living conditions of the human body. Significant and/or long-term deviations of oxygen and carbon dioxide concentrations from the normal values in blood can be a reason of significant pathological changes with irreversible consequences: lack of oxygen (hypoxia and ischemic events), the change in the acidbase balance of blood (acidosis or alkalosis), and others. In the context of a changing external environment and internal conditions of the body the action of its regulatory systems aimed at maintaining homeostasis. One of the major mechanisms for maintaining concentrations (partial pressures) of oxygen and carbon dioxide in the blood at a normal level is the regulation of minute ventilation, respiratory rate and depth of respiration, which is caused by the activity of the central and peripheral regulators.

In this paper we propose a mathematical model of the regulation of pulmonary ventilation parameter. The model is used to calculate the minute ventilation adaptation during hypoxia and hypercapnia. The model is developed using a single-component model of the lungs, and biochemical equilibrium conditions of oxygen and carbon dioxide in the blood and the alveolar lung volume. A comparison with laboratory data is performed during hypoxia and hypercapnia. Analysis of the results shows that the model reproduces the dynamics of minute ventilation during hypercapnia with sufficient accuracy. Another result is that more accurate model of regulation of minute ventilation during hypoxia should be developed. The factors preventing from satisfactory accuracy are analysed in the final section.

Respiratory function is one of the main limiting factors of the organism during intense physical activities. Thus, it is important characteristic of high performance sport and extreme physical activity conditions. Therefore, the results of this study have significant application value in the field of mathematical modeling in sport. The considered conditions of hypoxia and hypercapnia are partly reproduce training at high altitude and at hypoxia conditions. The purpose of these conditions is to increase the level of hemoglobin in the blood of highly qualified athletes. These conditions are the only admitted by sport committees.

As it stands in the contemporary world, compliance with regulations concerning data protection such as GDPR is central to organizations. Another important issue analysis identified is the fact that compliance is hampered by the fact that legal documents are often complex and that regulations are ever changing. This paper aims to describe the ways in which NLP aids in keeping GDPR compliance effortless through automated scanning for compliance, evaluating privacy policies, and increasing the level of transparency. The work does not only limit to exploring the application of NLP for dealing with the privacy policies and facilitate better understanding of the third-party data sharing but also proceed to perform the preliminary studies to evaluate the difference of several NLP models. They implement and execute the models to distinguish the one that performs the best based on the efficiency and speed at which it automates the process of compliance verification and analyzing the privacy policy. Moreover, some of the topics discussed in the research deal with the possibility of using automatic tools and data analysis to GDPR, for instance, generation of the machine readable models that assist in evaluation of compliance. Among the evaluated models from our studies, SBERT performed best at the policy level with an accuracy of 0.57, precision of 0.78, recall of 0.83, and F1-score of 0.80. BERT showed the highest performance at the sentence level, achieving an accuracy of 0.63, precision of 0.70, recall of 0.50, and F1-score of 0.55. Therefore, this paper emphasizes the importance of NLP to help organizations overcome the difficulties of GDPR compliance, create a roadmap to a more client-oriented data protection regime. In this regard, by comparing preliminary studies done in the test and showing the performance of the better model, it helps enhance the measures taken in compliance and fosters the defense of individual rights in the cyberspace.

This study proposes and analyzes a discrete-time mathematical model of population dynamics with seasonal reproduction, taking into account the density-dependent regulation and sex structure. In the model, population birth rate depends on the number of females, while density is regulated through juvenile survival, which decreases exponentially with increasing total population size. Analytical and numerical investigations of the model demonstrate that when more than half of both females and males survive, the population exhibits stable dynamics even at relatively high birth rates. Oscillations arise when the limitation of female survival exceeds that of male survival. Increasing the intensity of male survival limitation can stabilize population dynamics, an effect particularly evident when the proportion of female offspring is low. Depending on parameter values, the model exhibits stable, periodic, or irregular dynamics, including multistability, where changes in current population size driven by external factors can shift the system between coexisting dynamic modes. To apply the model to real populations, we propose an approach for estimating demographic parameters based on total abundance data. The key idea is to reduce the two-component discrete model with sex structure to a delay equation dependent only on total population size. In this formulation, the initial sex structure is expressed through total abundance and depends on demographic parameters. The resulting one-dimensional equation was applied to describe and estimate demographic characteristics of ungulate populations in the Jewish Autonomous Region. The delay equation provides a good fit to the observed dynamics of ungulate populations, capturing long-term trends in abundance. Point estimates of parameters fall within biologically meaningful ranges and produce population dynamics consistent with field observations. For moose, roe deer, and musk deer, the model suggests predominantly stable dynamics, while annual fluctuations are primarily driven by external factors and represent deviations from equilibrium. Overall, these estimates enable the analysis of structured population dynamics alongside short-term forecasting based on total abundance data.

Calcium is a major nutrient regulating metabolism in a plant. Deficiency of calcium results in a growth decline of plant tissues. Ca may be lost from forest soils due to acidic atmospheric deposition and tree harvesting. Plant-available calcium compounds are in the soil cation exchange complex and soil waters. Model of soil calcium dynamics linking it with the model of soil organic matter dynamics ROMUL in forest ecosystems is developed. ROMUL describes the mineralization and humification of the fraction of fresh litter which is further transformed into complex of partially humified substance (CHS) and then to stable humus (H) in dependence on temperature, soil moisture and chemical composition of the fraction (nitrogen, lignin and ash contents, pH). Rates of decomposition and humification being coefficients in the system of ordinary differential equations are evaluated using laboratory experiments and verified on a set of field experiments. Model of soil calcium dynamics describes calcium flows between pools of soil organic matter. Outputs are plant nutrition, leaching, synthesis of secondary minerals. The model describes transformation and mineralization of forest floor in detail. Experimental data for calibration model was used from spruсe forest of Bulgaria.

The results of determination of the risk of cardiovascular failure of young athletes and adolescents in stressful physical activity have been demonstrated. The method of screening diagnostics of the risk of developing heart failure has been described. The results of contactless measurement of the form of the pulse wave of the radial artery using semiconductor laser autodyne have been presented. In the measurements used laser diode type RLD-650 specifications: output power of 5 mW, emission wavelength 654 nm. The problem was solved by the reduced form of the reflector movement, which acts as the surface of the skin of the human artery, tested method of assessing the risk of cardiovascular disease during exercise and the analysis of the results of its application to assess the risk of cardiovascular failure reactions of young athletes. As analyzed parameters were selected the following indicators: the steepness of the rise in the systolic portion of the fast and slow phase, the rate of change in the pulse wave catacrota variability of cardio intervals as determined by the time intervals between the peaks of the pulse wave. It analyzed pulse wave form on its first and second derivative with respect to time. The zeros of the first derivative of the pulse wave allow to set aside time in systolic rise. A minimum of the second derivative corresponds to the end of the phase and the beginning of the slow pressure build-up in the systole. Using the first and second derivative of the pulse wave made it possible to separately analyze the pulse wave form phase of rapid and slow pressure increase phase during systolic expansion. It has been established that the presence of anomalies in the form of the pulse wave in combination with vagotonic nervous regulation of the cardiovascular system of a patient is a sign of danger collapse of circulation during physical exercise.

Industrial robots have made it possible for robotics to become a worldwide discipline both in economy and in science. However, their capabilities are limited, especially regarding contact tasks where it is required to regulate or at least limit contact forces. At one point, it was noticed that elasticity in the joint transmission, which was treated as a drawback previously, is actually helpful in this regard. This observation led to the introduction of elastic joint robots that are well-suited to contact tasks and cooperative behavior in particular, so they become more and more widespread nowadays. Many researchers try to implement such devices not with trivial series elastic actuators (SEA) but with more sophisticated variable stiffness actuators (VSA) that can regulate their own mechanical stiffness. All elastic actuators demonstrate shock robustness and safe interaction with external objects to some extent, but when stiffness may be varied, it provides additional benefits, e. g., in terms of energy efficiency and task adaptability. Here, we present a novel variable stiffness actuator with a magnetic coupler as an elastic element. Magnetic transmission is contactless and thus advantageous in terms of robustness to misalignment. In addition, the friction model of the transmission becomes less complex. It also has milder stiffness characteristic than typical mechanical nonlinear springs, moreover, the stiffness curve has a maximum after which it descends. Therefore, when this maximum torque is achieved, the coupler slips, and a new pair of poles defines the equilibrium position. As a result, the risk of damage is smaller for this design solution. The design of the joint is thoroughly described, along with its mathematical model. Finally, the control system is also proposed, and simulation tests confirm the design ideas.

A model of the behavior of the active neuron, which was the development of the model described in Shamis A.L. [Shamis, 2006], is designed. Proposed topology is locally connected matrix of the active neural network and the structure integration of information from different sources. An example of the script behavior robot controlled by this neural network is described. The results of experiments with the software implementation of a neural network are presented.

Investigation of the influence of external fields on living systems is one of the most interesting and rapidly developing areas of modern biophysics. However, the mechanisms of such an impact are still not entirely clear. One approach to the study of this issue is associated with modeling the interaction of external fields with internal mobility of biological objects. In this paper, this approach is used to study the effect of external fields on the motion of local conformational distortions — kinks, in the DNA molecule. Realizing and taking into account that on the whole this task is closely connected with the problem of the mechanisms of regulation of vital processes of cells and cellular systems, we set the problem — to investigate the physical mechanisms regulating the motion of kinks and also to answer the question whether permanent and periodic fields can play the role of regulators of this movement. The paper considers the most general case, when constant and periodic fields are switching on and off asynchronously. Three variants of asynchronous switching on/off are studied in detail. In the first variant, the time intervals (or diapasons) of the actions of the constant and periodic fields do not overlap, in the second — overlap, and in the third — the intervals are putting in each other. The calculations were performed for the sequence of plasmid pTTQ18. The kink motion was modeled by the McLaughlin–Scott equation, and the coefficients of the equation were calculated in a quasi-homogeneous approximation. Numerical experiments showed that constant and periodic fields exert a significant influence on the character of the kink motion and regulate it. So the switching on of a constant field leads to a rapid increase of the kink velocity and to the establishment of a stationary velocity of motion, and the switching on of a periodic field leads to the steady oscillations of the kink with the frequency of the external periodic field. It is shown that the behavior of the kink depends on the mutual arrangement of the diapasons of the action of the external fields. As it turned out, events occurring in one of the two diapasons can affect the events in the other diapason, even when the diapasons are sufficiently far apart. It is shown that the overlapping of the diapasons of action of the constant and periodic fields leads to a significant increase in the path traversed by the kink to a complete stop. Maximal growth of the path is observed when one diapason is putting in each other. In conclusion, the question of how the obtained model results could be related to the most important task of biology — the problem of the mechanisms of regulation of the processes of vital activity of cells and cellular systems is discussed.

The paper studies the influence of selective harvest on dynamic modes of the «predator–prey» community with age structure for prey. We use a slight modification of the Nicholson-Bailey model to describe the interaction between predator and prey. We assume the prey population size is regulated by a decrease in survival rate of juvenile with an increase in the size of age class. The aim is to study the mechanisms of formation and evolution of dynamic modes for the structured «predator–prey» community model due to selective harvesting. We considered the cases when a harvest of some part of predator or prey population or one of the prey’s age classes is realized. The conditions of stable coexistence of interacting species and scenarios of the occurrence of oscillatory modes of abundance are studied. It is shown the harvesting of only young individuals of prey or simultaneous removal of young and adult individuals leads to expansion of parameter space domain with stable dynamics of prey population both with and without a predator. At the same time, the bistability domain narrows, in which changing initial conditions leads to the predator either remains in the community or dies from lack of food. In the case of the harvest for prey adult individuals or predator, the predator preservation in the community is ensured by high values of the prey birth rate, moreover bistability domain expands. With the removal of both juvenile preys and predators, an increase in the survival rates of adult prey leads to stabilization of the community dynamics. The juveniles’ harvest can lead to damping of oscillations and stabilize the prey dynamics in the predator absence. Moreover, it can change the scenario of the coexistence of species — from habitation of preys without predators to a sustainable coexistence of both species. The harvest of some part of predator or prey or the prey’s older age class can lead to both oscillations damping and stable dynamics of the interacting species, and to the destruction of the community, that is, to the death of predator.

In this work, we analyze the system of contracts made by Russian defense enterprises in the process of state defense order execution. We conclude that methods of statistical mechanics can be applied to the description of the given system. Following the original grand-canonical ensemble approach, we can create the statistical ensemble under investigation as a set of instant snapshots of indistinguishable contracts having individual values. We show that due to government regulations of contract prices the contract system can be described in terms of nonextensive Tsallis statistics. We have found that probability distributions of contract prices correspond to deformed Bose – Einstein distributions obtained using nonextensive Tsallis entropy. This conclusion is true both in the case of the whole set of contracts and in the case of the contracts made by an individual defense company as a seller.

In order to analyze how deformed Bose – Einstein distributions fit the empirical contract price distributions we compare the corresponding cumulative distribution functions. We conclude that annual distributions of individual sales which correspond to each company’s contract (order) can be used as relevant data for contract price distributions analysis. The empirical cumulative distribution functions for the individual sales ranking of Concern CSRI Elektropribor, one of the leading Russian defense companies, are analyzed for the period 2007–2021. The theoretical cumulative distribution functions, obtained using deformed Bose – Einstein distributions in the case of «rare contract gas» limit, fit well to the empirical cumulative distribution functions. The fitted values for the entropic index show that the degree of nonextensivity of the system under investigations is rather high. It is shown that the characteristic prices of distributions can be estimated by weighing the values of annual individual sales with the escort probabilities. Given that the fitted values of chemical potential are equal to zero, we suggest that «gas of contracts» can be compared to photon gas in which the number of particles is not conserved.