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Search Results: 1 - 10 of 1544 matches for " Svetlana Postnova "
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Adaptation to Shift Work: Physiologically Based Modeling of the Effects of Lighting and Shifts’ Start Time
Svetlana Postnova, Peter A. Robinson, Dmitry D. Postnov
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0053379
Abstract: Shift work has become an integral part of our life with almost 20% of the population being involved in different shift schedules in developed countries. However, the atypical work times, especially the night shifts, are associated with reduced quality and quantity of sleep that leads to increase of sleepiness often culminating in accidents. It has been demonstrated that shift workers’ sleepiness can be improved by a proper scheduling of light exposure and optimizing shifts timing. Here, an integrated physiologically-based model of sleep-wake cycles is used to predict adaptation to shift work in different light conditions and for different shift start times for a schedule of four consecutive days of work. The integrated model combines a model of the ascending arousal system in the brain that controls the sleep-wake switch and a human circadian pacemaker model. To validate the application of the integrated model and demonstrate its utility, its dynamics are adjusted to achieve a fit to published experimental results showing adaptation of night shift workers (n = 8) in conditions of either bright or regular lighting. Further, the model is used to predict the shift workers’ adaptation to the same shift schedule, but for conditions not considered in the experiment. The model demonstrates that the intensity of shift light can be reduced fourfold from that used in the experiment and still produce good adaptation to night work. The model predicts that sleepiness of the workers during night shifts on a protocol with either bright or regular lighting can be significantly improved by starting the shift earlier in the night, e.g.; at 21:00 instead of 00:00. Finally, the study predicts that people of the same chronotype, i.e. with identical sleep times in normal conditions, can have drastically different responses to shift work depending on their intrinsic circadian and homeostatic parameters.
Diversity and Noise Effects in a Model of Homeostatic Regulation of the Sleep-Wake Cycle
Marco Patriarca ,Svetlana Postnova,Hans A. Braun,Emilio Hernández-García,Raúl Toral
PLOS Computational Biology , 2012, DOI: 10.1371/journal.pcbi.1002650
Abstract: Recent advances in sleep neurobiology have allowed development of physiologically based mathematical models of sleep regulation that account for the neuronal dynamics responsible for the regulation of sleep-wake cycles and allow detailed examination of the underlying mechanisms. Neuronal systems in general, and those involved in sleep regulation in particular, are noisy and heterogeneous by their nature. It has been shown in various systems that certain levels of noise and diversity can significantly improve signal encoding. However, these phenomena, especially the effects of diversity, are rarely considered in the models of sleep regulation. The present paper is focused on a neuron-based physiologically motivated model of sleep-wake cycles that proposes a novel mechanism of the homeostatic regulation of sleep based on the dynamics of a wake-promoting neuropeptide orexin. Here this model is generalized by the introduction of intrinsic diversity and noise in the orexin-producing neurons, in order to study the effect of their presence on the sleep-wake cycle. A simple quantitative measure of the quality of a sleep-wake cycle is introduced and used to systematically study the generalized model for different levels of noise and diversity. The model is shown to exhibit a clear diversity-induced resonance: that is, the best wake-sleep cycle turns out to correspond to an intermediate level of diversity at the synapses of the orexin-producing neurons. On the other hand, only a mild evidence of stochastic resonance is found, when the level of noise is varied. These results show that disorder, especially in the form of quenched diversity, can be a key-element for an efficient or optimal functioning of the homeostatic regulation of the sleep-wake cycle. Furthermore, this study provides an example of a constructive role of diversity in a neuronal system that can be extended beyond the system studied here.
A Physiologically Based Model of Orexinergic Stabilization of Sleep and Wake
Ben D. Fulcher, Andrew J. K. Phillips, Svetlana Postnova, Peter A. Robinson
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0091982
Abstract: The orexinergic neurons of the lateral hypothalamus (Orx) are essential for regulating sleep-wake dynamics, and their loss causes narcolepsy, a disorder characterized by severe instability of sleep and wake states. However, the mechanisms through which Orx stabilize sleep and wake are not well understood. In this work, an explanation of the stabilizing effects of Orx is presented using a quantitative model of important physiological connections between Orx and the sleep-wake switch. In addition to Orx and the sleep-wake switch, which is composed of mutually inhibitory wake-active monoaminergic neurons in brainstem and hypothalamus (MA) and the sleep-active ventrolateral preoptic neurons of the hypothalamus (VLPO), the model also includes the circadian and homeostatic sleep drives. It is shown that Orx stabilizes prolonged waking episodes via its excitatory input to MA and by relaying a circadian input to MA, thus sustaining MA firing activity during the circadian day. During sleep, both Orx and MA are inhibited by the VLPO, and the subsequent reduction in Orx input to the MA indirectly stabilizes sustained sleep episodes. Simulating a loss of Orx, the model produces dynamics resembling narcolepsy, including frequent transitions between states, reduced waking arousal levels, and a normal daily amount of total sleep. The model predicts a change in sleep timing with differences in orexin levels, with higher orexin levels delaying the normal sleep episode, suggesting that individual differences in Orx signaling may contribute to chronotype. Dynamics resembling sleep inertia also emerge from the model as a gradual sleep-to-wake transition on a timescale that varies with that of Orx dynamics. The quantitative, physiologically based model developed in this work thus provides a new explanation of how Orx stabilizes prolonged episodes of sleep and wake, and makes a range of experimentally testable predictions, including a role for Orx in chronotype and sleep inertia.
Tensor powers for non-simply laced Lie Algebras $B_2$ case
Petr P. Kulish,Vladimir D. Lyakhovsky,Olga P. Postnova
Mathematics , 2011, DOI: 10.1088/1742-6596/346/1/012012
Abstract: We study the decomposition problem for tensor powers of $B_2$-fundamental modules. To solve this problem singular weight technique and injection fan algorithms are applied. Properties of multiplicity coefficients are formulated in terms of multiplicity functions. These functions are constructed showing explicitly the dependence of multiplicity coefficients on the highest weight coordinates and the tensor power parameter. It is thus possible to study general properties of multiplicity coefficients for powers of the fundamental $B_2$- modules.
Optical Constants for MBE n-Type GaAs Films Doped by Si or Te between 1.50-4.75 eV  [PDF]
Svetlana N. Svitasheva
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2010, DOI: 10.4236/jemaa.2010.26046
Abstract: The thickness and spectral dependence of the complex refractive index of upper layer in thin-film MBE-grown GaAs heterostructures were calculated basing on an classical oscillatory model of dielectric function from spectra measured by spectroscopic ellipsometry (nondestructive, contactless optical method) in the range of 1.5-4.75 eV.
Traditional Institutions and Knowledge of Siberian Aboriginal Community  [PDF]
Svetlana Panakarova, Maxim Vlasov
Modern Economy (ME) , 2013, DOI: 10.4236/me.2013.49061
Abstract:

The purpose of this paper is to discuss the perspectives of the use of traditional knowledge in national socio-economic development in general and in the development of local communities of aboriginal nations of Siberia in particular. This study aims to analyze the traditional economic activity with the help of the questionnaire of 1500 respondents (from different ethnic groups) in different parts of the Siberian region—Khakasia. The results of empirical research have shown that in Khakas communities traditional kinds of activity are extended and they are of great importance for people as earlier. The comparative analysis of labor productivity in animal husbandry and wildlife management allows to draw a conclusion of the positive influence of traditional knowledge in these fields of activity. Some clusters of traditional economic institutions of the indigenous people of Southern Siberia have been identified such as: institutions for corporate property of land, institutions for private property of cattle, institutions for labor mutual aid, institutions for wandering, institutions for communal managements. The results of evolution of traditional institutions and their current state are presented. Even the transformed institutions are accepted by members of national communities as earlier. Therefore they can become the effective instrument of social and economic development of indigenous people territories. The spiraling process of traditional knowledge of Khakas people is explained in the SECI Model. According to the research, regarding the Khakas community, the management process of knowledge has to include three types of economic agents: local government authorities, entrepreneurs, members of Khakas community. Three strategies to manage the traditional knowledge are recommended such as: animal husbandry development, commercialization of traditional wildlife management, realization of a state policy taking into consideration the existence of traditional institutions. The research demonstrates the traditional knowledge may be the factor of economic increase and social development for local society. Moreover, it is a national heritage and it needs to be managed.

Social-Psychological Model of the “Migration Circle”: Potential Emigrants, Migrants,Remigrants  [PDF]
Svetlana Gurieva, Tamara Kinunen
Open Journal of Social Sciences (JSS) , 2014, DOI: 10.4236/jss.2014.211023
Abstract: А fundamentally new model of “migration circle” is considered in accordance with modern theo-ries of migration and adaptation. This model is represented in the following basic stages: starting- up (the potential emigrants), the main (directly emigrants), and final (re-emigrants). The benchmark analysis of values and dominant ethnic tendencies of migrants residing at different stages of migration (at the miscellaneous points of the “migration circle”) has revealed the existing of the significant differences in the value preferences’ structure, dominant ethnic tendencies, social and cultural distance. The received data allow forecasting accurate to 72% the emigrants’ success of adaptation to a new social and cultural environment. Accumulating during the investigation scientific theoretical material allows finding solution of many practical problems arising at the threshold of emigration (potential emigrants) either in situations of the return to Motherland (re-emigrants).
How Did the Yakuts Fortify Themselves against the Cold?  [PDF]
Svetlana Ivanovna Petrova
Open Journal of Social Sciences (JSS) , 2015, DOI: 10.4236/jss.2015.33017
Abstract: This article is dedicated to the analysis of the heat-insulating function of winter clothes and personal cold-protective equipments (protectors), which grew out of use at the beginning of the XX century and now are kept in different museum funds. The author pays the main attention to the description of the material, production technologies, and functional heat-insulating properties of the traditional winter clothes and protectors. The article also discusses ethnocultural parallels of the traditional clothes.
The relationship of mineral and geochemical composition to artificial radionuclide partitioning inYenisei river sediments downstream frommining-and-chemical combine rosatom  [PDF]
Bondareva Lydia, Artamonova Svetlana
Natural Science (NS) , 2011, DOI: 10.4236/ns.2011.37073
Abstract: Discharges from the Mining-and-Chemical Com- bine (MCC) of Rosatom, downstream from Krasnoyarsk-26, near of the Krasnoyarsk resulted in radioactive contamination of sedi-ments of the River Yenisei. The concentration of artificial gammaemitting radionuclides (137Cs, 60Co, 152Eu, and 241Am) was determined to analyze the migration processes leading to the transport of these radionuclides. The concentration of artificial radionuclides in the surface layers of the studied area varied in wide ranges: 137Cs – 318 - 1800 Bq/kg, 60Co – 87 - 720 Bq/kg, 152Eu – 12 - 287 Bq/kg and 241Am – 6 - 76 Bq/kg. There was a sequence of migration of radionuclides investigated in the surface layer of sedi-ments that were collected in the near zone of influence of the MCC: 241Am ≈ 152Eu >60Co >137Cs. Radionuclide species have been found to be directly related to sediment structure and composition.
Calcitonin Participant in the Development of Insulin Resistance  [PDF]
Svetlana Stepanovna Moisa
Journal of Biomedical Science and Engineering (JBiSE) , 2017, DOI: 10.4236/jbise.2017.107026
Abstract: The review contains contemporary literature data about calcitonin role in the development of insulin resistance and its potential role in the pathogenesis of carbohydrate metabolism disturbances. Analogues disturbances revealed under diabetes mellitus and under calcitonin treatment are considered. Literature data about hormone diabetogenicity are discussed. The analysis of experimental and literature data testifies that calcitonin under unfavorable conditions (age, obesity, stress) against the background of the decreasing of functional activity of insular apparatus can lead to the development of metabolic syndrome and diabetes mellitus. It is shown that calcium channel blockers inhibit calcitonin effect leads to glucose intolerance and decreases tissue insulin sensitivity. In this connection a question about direct influence on calcium mechanisms of endocrine system as possible method of drug therapy is discussed.
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