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41.
Yukihiko Nakata Toshikazu Kuniya 《Journal of Mathematical Analysis and Applications》2010,363(1):230-9
In this paper, we study a class of periodic SEIRS epidemic models and it is shown that the global dynamics is determined by the basic reproduction number R0 which is defined through the spectral radius of a linear integral operator. If R0<1, then the disease free periodic solution is globally asymptotically stable and if R0>1, then the disease persists. Our results really improve the results in [T. Zhang, Z. Teng, On a nonautonomous SEIRS model in epidemiology Bull. Math. Biol. 69 (8) (2007) 2537-2559] for the periodic case. Moreover, from our results, we see that the eradication policy on the basis of the basic reproduction number of the time-averaged system may overestimate the infectious risk of the periodic disease. Numerical simulations which support our theoretical analysis are also given. 相似文献
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Paul Leonard Salceanu Hal L. Smith 《Journal of Difference Equations and Applications》2013,19(1):73-103
Discrete-time SI and SIR epidemic models, formulated by Emmert and Allen [J. Differ. Equ. Appl., 10 (2004), pp. 1177–1199] for the spread of a fungal disease in a structured amphibian host population, are analysed. Criteria for persistence of the population as well as for persistence of the disease are established. Global stability results for host extinction and for the disease-free equilibrium are presented. 相似文献
45.
A biomathematical model is described by stochastic differential equations with Markovian switching. The long‐time dynamical properties are studied both theoretically and numerically. Results show that both the persistence and extinction have close relationship with environmental noises (white and color noises). These results are of important biological significance for biological conservation. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Ramsés Djidjou-Demasse Gbenga J. Abiodun Abiodun M. Adeola Joel O. Botai 《Studies in Applied Mathematics》2020,144(4):389-411
In this paper, we develop and analyze a malaria model with seasonality of mosquito life-history traits: periodic-mosquitoes per capita birth rate, -mosquitoes death rate, -probability of mosquito to human disease transmission, -probability of human to mosquito disease transmission, and -mosquitoes biting rate. All these parameters are assumed to be time dependent leading to a nonautonomous differential equation system. We provide a global analysis of the model depending on two threshold parameters and (with ). When , then the disease-free stationary state is locally asymptotically stable. In the presence of the human disease-induced mortality, the global stability of the disease-free stationary state is guarantied when . On the contrary, if , the disease persists in the host population in the long term and the model admits at least one positive periodic solution. Moreover, by a numerical simulation, we show that a sub-critical (backward) bifurcation is possible at . Finally, the simulation results are in accordance with the seasonal variation of the reported cases of a malaria-epidemic region in Mpumalanga province in South Africa. 相似文献
49.
Lisa R. Volpatti Tuomas P. J. Knowles 《Journal of Polymer Science.Polymer Physics》2014,52(4):281-292
Amyloid structures constitute a class of highly ordered nanomaterials formed by insoluble protein aggregates. These aggregates are characterized by a cross‐β structural motif in which β‐sheets are oriented perpendicular to the fibril axis and bound together by a dense hydrogen bonding network. Although they have been associated with several neurodegenerative disorders, such as Alzheimer's and Parkinson's diseases, amyloid fibrils have also been found in many physiologically beneficial roles, for instance in adhesives and hormone storage. Inspired by this natural occurrence of functional amyloid, the hierarchal self‐assembly of these structures has recently been used to develop artificial biomaterials for applications in medicine and nanotechnology. In order to realize the full potential of amyloids as functional materials, it is important to understand their fundamental mechanical properties. This review explores a range of experimental strategies to determine the mechanical properties of amyloid fibrils and discusses the results in the context of polymer physics concepts. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 281–292 相似文献
50.
A conjecture by G. Ladas 总被引:5,自引:0,他引:5
LIXIANYI TANGHENGSHENG LIUYACHUN XIAOGONGFU 《高校应用数学学报(英文版)》1998,13(1):39-44
In this paper, a sufficient condition for boundedness and persistence of the solu1 /of the following delay difference equation is obtained. A conjecture by G. Ladas is proved here xn-1=A/x^pn B/x^qn-1, n=0,1,...where A, B, p, q, x-1, xo∈(0,∞). 相似文献