Chimera states in ensembles of excitable FitzHugh-Nagumo systems

An ensemble of nonlocally coupled excitable FitzHugh-Nagumo systems is studied. In the presence of noise the explored system can exhibit a special kind of chimera states called coherence-resonance chimera. As previously thought, noise plays principal role in forming these structures. It is shown in the present paper that these regimes appear because of the specific coupling between the elements. The action of coupling involve a spatial wave regime, which occurs in ensemble of excitable nodes even if the noise is switched off. In addition, a new chimera state is obtained in an excitable regime. It is shown that the noise makes this chimera more stable near an Andronov-Hopf bifurcation.Comment: 12 pages,7 figure

Time-delayed feedback control of coherence resonance chimeras

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Chaos 27, 114320 (2017) and may be found at https://doi.org/10.1063/1.5008385.Using the model of a FitzHugh-Nagumo system in the excitable regime, we investigate the influence of time-delayed feedback on noise-induced chimera states in a network with nonlocal coupling, i.e., coherence resonance chimeras. It is shown that time-delayed feedback allows for the control of the range of parameter values where these chimera states occur. Moreover, for the feedback delay close to the intrinsic period of the system, we find a novel regime which we call period-two coherence resonance chimera. Coherence resonance chimeras in nonlocally coupled networks of excitable elements represent partial synchronization patterns composed of spatially separated domains of coherent and incoherent spiking behavior, which are induced by noise. These patterns are different from classical chimera states occurring in deterministic oscillatory systems and combine properties of the counter-intuitive phenomenon of coherence resonance, i.e., a constructive role of noise, and chimera states, i.e., the coexistence of spatially synchronized and desynchronized domains in a network of identical elements. Another distinctive feature of the particular type of chimera we study here is its alternating behavior, i.e., periodic switching of the location of coherent and incoherent domains. Applying time-delayed feedback, we demonstrate how to control coherence resonance chimeras by adjusting delay time and feedback strength. In particular, we show that feedback increases the parameter intervals of existence of chimera states and has a significant impact on their alternating dynamics leading to the appearance of novel patterns, which we call period-two coherence resonance chimera. Since the dynamics of every individual network element in our study is given by the FitzHugh-Nagumo (FHN) system, which is a paradigmatic model for neurons in the excitable regime, we expect wide-range applications of our results to neural networks.DFG, 163436311, SFB 910: Kontrolle selbstorganisierender nichtlinearer Systeme: Theoretische Methoden und Anwendungskonzept

Monitoring of food security in the Russian Federation : methodology and assessment

The paper presents the results of food security research in the Russia Federation. Providing food security and country’s independence becomes the core of keeping the national sovereignty under conditions of globalization and integration processes development. It determined the research relevance. The purpose of the research is the development of a new methodological approach to monitoring of food security as one of most important components of an efficient protection system of the latter. Integrative reproduction approach to monitoring of country’s food security meeting stability criteria, economic and social ecological efficiency, competitive ability and safety is suggested. The composition of indicators arranged in four groups is developed within the framework of such approach in order to carry out all-round monitoring of Russian Federation’s food security: agroindustrial complex production capacity and its efficient use; food accessibility; food affordability; food quality and level. The assessment of Russian Federation’s agriculture facilities, agricultural products output dynamics, agricultural raw materials and provisions export and import, level of staple foods consumption by the population and Russians’ diet is given based on indicative analysis. The main threats to Russia’s food security are revealed (productive powers deindustrialization; low level of investment to the agricultural sector; labour force reduction; increase in dependence on imported foodstuff; population’s low income level and living standards, etc.) Recommendations regarding Russian Federation’s food security level increase are given (carrying out augmented technologic modernization, establishing a brand new enterprise network, development of associations and cooperatives, increase in government control combined with agricultural producers’ business activity, development of market forms of cooperation and integration).peer-reviewe

Mechanism of solitary state appearance in an ensemble of nonlocally coupled Lozi maps

We study the peculiarities of the solitary state appearance in the ensemble of nonlocally coupled chaotic maps. We show that nonlocal coupling and features of the partial elements lead to arising of multistability in the system. The existence of solitary state is caused by formation of two attractive sets with different basins of attraction. Their basins are analysed depending on coupling parameters.Comment: 7 figures and 11 page

Delay-induced self-oscillation excitation in the FitzHugh-Nagumo model: regular and chaotic dynamics

The stochastic FitzHugh-Nagumo model with time delayed-feedback is often studied in excitable regime to demonstrate the time-delayed control of coherence resonance. Here, we show that the impact of time-delayed feedback in the FitzHugh-Nagumo neuron is not limited by control of noise-induced oscillation regularity (coherence), but also results in excitation of the regular and chaotic self-oscillatory dynamics in the deterministic model. We demonstrate this numerically by means of simulations, linear stability analysis, the study of Lyapunov exponents and basins of attraction for both positive and negative delayed-feedback strengths. It has been established that one can implement a route to chaos in the explored model, where the intrinsic peculiarities of the Feigenbaum scenario are exhibited. For large time delay, we complement the study of temporal evolution by the interpretation of the dynamics as patterns in virtual space.Comment: 12 pages, 11 figures in the main text and 3 figures in appendi

Innovation as a Factor in Sustainable Development of Russia’s Agriculture

Sustainable agriculture is an integral aspect of the sustainable development of a socio-economic system. In this regard, innovation is considered to be one of the leading factors ensuring the development of sustainable agricultural since it increases the efficiency and competitiveness of the industry in the domestic and foreign markets. This study presents a system of recursive equations characterizing the innovations occurring within agricultural organizations in the regions of the Russian Federation. Additionally, the study assesses the sustainability of agricultural development in Russia by calculating the integrated index of five components: economic, innovative, social, ecological, and institutional. Also, the authors built a regression model that estimates the influence of innovation on the sustainability of agricultural development in Russia

The Risk Factors of Thrombogenic, Thrombophilia, and the Principle for Heparin Prophylaxis in Personalized Medicine

This chapter presents new views on thrombogenic risk factors, thrombophilia, and thrombotic state of readiness preceding the thrombus formation. The modern methods of laboratory diagnostics of thrombotic state of readiness are considered to initiate thromboprophylaxis in patients irrespective of the presence of thrombophilia, as well as certain thrombogenic risk factors

Symbiosis of an artificial neural network and models of biological neurons: training and testing

In this paper we show the possibility of creating and identifying the features of an artificial neural network (ANN) which consists of mathematical models of biological neurons. The FitzHugh--Nagumo (FHN) system is used as an example of model demonstrating simplified neuron activity. First, in order to reveal how biological neurons can be embedded within an ANN, we train the ANN with nonlinear neurons to solve a a basic image recognition problem with MNIST database; and next, we describe how FHN systems can be introduced into this trained ANN. After all, we show that an ANN with FHN systems inside can be successfully trained and its accuracy becomes larger. What has been done above opens up great opportunities in terms of the direction of analog neural networks, in which artificial neurons can be replaced by biological ones. \end{abstract}Comment: 6 pages, 7 figures, 2 table