This paper investigates the local bifurcations of a CTL response model published by Nowak and Bangham [M.A. Nowak, C.R.M. Bangham, Population dynamics of immune responses to persistent viruses, Science 272 (1996) 74]. The Nowak-Bangham model can have three equilibria depending on the basic reproduction number, and generates a Hopf bifurcation through two bifurcations of equilibria. The main result shows a sufficient condition for the interior equilibrium to have a unique bifurcation point at which a simple Hopf bifurcation occurs. For this proof, some new techniques are developed in order to apply the method established by Liu [W.M. Liu, Criterion of Hopf bifurcations without using eigenvalues, J. Math. Anal. Appl. 182 (1) (1994) 250]. In addition, to demonstrate the result obtained theoretically, some bifurcation diagrams are presented with numerical examples.
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http://dx.doi.org/10.1016/j.mbs.2009.06.005 | DOI Listing |
Math Biosci Eng
February 2015
Graduate School of Environmental and Life Sciences, Okayama University, 3-1-1, Tsushima-Naka, Okayama, Japan.
We present a constructive method for Lyapunov functions for ordinary differential equation models of infectious diseases in vivo. We consider models derived from the Nowak-Bangham models. We construct Lyapunov functions for complex models using those of simpler models.
View Article and Find Full Text PDFMath Biosci
September 2009
Department of Digital Engineering, Numazu National College of Technology, Numazu, Shizuoka, Japan.
This paper investigates the local bifurcations of a CTL response model published by Nowak and Bangham [M.A. Nowak, C.
View Article and Find Full Text PDFAn Acad Bras Cienc
March 2000
Departmento de Estatística, Matemática Aplicada e Computacional Universidade Estadual Paulista-UNESP, SP, Brasil.
In recent years, many researchers in the field of biomedical sciences have made successful use of mathematical models to study, in a quantitative way, a multitude of phenomena such as those found in disease dynamics, control of physiological systems, optimization of drug therapy, economics of the preventive medicine and many other applications. The availability of good dynamic models have been providing means for simulation and design of novel control strategies in the context of biological events. This work concerns a particular model related to HIV infection dynamics which is used to allow a comparative evaluation of schemes for treatment of AIDS patients.
View Article and Find Full Text PDFIMA J Math Appl Med Biol
March 1999
Department of Applied Mathematics, Hong Kong Polytechnic University, Kowloon.
As biology becomes more quantitative, it appears that the increasing use of mathematics in this area is inevitable. In 1996, Nowak & Bangham (1996, Science 272, 74-79) proposed three mathematical models to explore the relation between antiviral immune responses, virus load, and virus diversity. In this paper we investigate the delay effect in a model which considers the interaction between a replicating virus and host cells.
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