scholarly journals Hopf Bifurcation and Stability of Periodic Solutions for Delay Differential Model of HIV Infection of CD4+T-cells

2014 ◽  
Vol 2014 ◽  
pp. 1-18 ◽  
Author(s):  
P. Balasubramaniam ◽  
M. Prakash ◽  
Fathalla A. Rihan ◽  
S. Lakshmanan
Keyword(s):  
T Cells ◽  
Steady State ◽  
Hopf Bifurcation ◽  
Time Delay ◽  
Hiv Infection ◽  
Logistic Growth ◽  
Differential Model ◽  
Discrete Time Delay ◽  
The Stability ◽  
Delay Differential

This paper deals with stability and Hopf bifurcation analyses of a mathematical model of HIV infection ofCD4+T-cells. The model is based on a system of delay differential equations with logistic growth term and antiretroviral treatment with a discrete time delay, which plays a main role in changing the stability of each steady state. By fixing the time delay as a bifurcation parameter, we get a limit cycle bifurcation about the infected steady state. We study the effect of the time delay on the stability of the endemically infected equilibrium. We derive explicit formulae to determine the stability and direction of the limit cycles by using center manifold theory and normal form method. Numerical simulations are presented to illustrate the results.

scholarly journals A Differential Equation Model of HIV Infection ofCD4+T-Cells with Delay

2008 ◽  
Vol 2008 ◽  
pp. 1-16 ◽  
Author(s):  
Junyuan Yang ◽  
Xiaoyan Wang ◽  
Fengqin Zhang
Keyword(s):  
T Cells ◽  
Time Delay ◽  
Hiv Infection ◽  
Equation Model ◽  
Feasible Region ◽  
Delay Model ◽  
Cure Rate ◽  
Differential Delay ◽  
Discrete Time Delay ◽  
The Stability

An epidemic model of HIV infection ofCD4+T-cells with cure rate and delay is studied. We include a baseline ODE version of the model, and a differential-delay model with a discrete time delay. The ODE model shows that the dynamics is completely determined by the basic reproduction numberR0<1. IfR0<1, the disease-free equilibrium is asymptotically stable and the disease dies out. IfR0>1, a unique endemic equilibrium exists and is globally stable in the interior of the feasible region. In the DDE model, the delay stands for the incubation time. We prove the effect of that delay on the stability of the equilibria. We show that the introduction of a time delay in the virus-to-healthy cells transmission term can destabilize the system, and periodic solutions can arise through Hopf bifurcation.

scholarly journals Modelling the Drugs Therapy for HIV Infection with Discrete-Time Delay

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Xueyong Zhou ◽  
Xiangyun Shi
Keyword(s):  
Time Delay ◽  
Hiv Infection ◽  
Discrete Time ◽  
Positive Equilibrium ◽  
Normal Form Theory ◽  
Discrete Time Delay ◽  
Form Theory ◽  
The Stability ◽  
Delay Differential ◽  
Two Equilibria

A discrete-time-delay differential mathematical model that described HIV infection of CD4+T cells with drugs therapy is analyzed. The stability of the two equilibria and the existence of Hopf bifurcation at the positive equilibrium are investigated. Using the normal form theory and center manifold argument, the explicit formulas which determine the stability, the direction, and the period of bifurcating periodic solutions are derived. Numerical simulations are carried out to explain the mathematical conclusions.

scholarly journals Stability and Hopf Bifurcation Analysis of a Vector-Borne Disease with Time Delay

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Yuanyuan Chen ◽  
Ya-Qing Bi
Keyword(s):  
Hopf Bifurcation ◽  
Time Delay ◽  
Bifurcation Theory ◽  
Center Manifold ◽  
Local Analysis ◽  
Normal Form Theory ◽  
Form Theory ◽  
Vector Borne ◽  
The Stability ◽  
Delay Differential

A delay-differential modelling of vector-borne is investigated. Its dynamics are studied in terms of local analysis and Hopf bifurcation theory, and its linear stability and Hopf bifurcation are demonstrated by studying the characteristic equation. The stability and direction of Hopf bifurcation are determined by applying the normal form theory and the center manifold argument.

scholarly journals Stability and Hopf Bifurcation Analysis of a Nutrient-Phytoplankton Model with Delay Effect

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Xinhong Pan ◽  
Min Zhao ◽  
Chuanjun Dai ◽  
Yapei Wang
Keyword(s):  
Hopf Bifurcation ◽  
Time Delay ◽  
Center Manifold ◽  
Center Manifold Theory ◽  
Delay Effect ◽  
Delay Differential System ◽  
The Stability ◽  
Delay Differential ◽  
Manifold Theory ◽  
Two Equilibria

A delay differential system is investigated based on a previously proposed nutrient-phytoplankton model. The time delay is regarded as a bifurcation parameter. Our aim is to determine how the time delay affects the system. First, we study the existence and local stability of two equilibria using the characteristic equation and identify the condition where a Hopf bifurcation can occur. Second, the formulae that determine the direction of the Hopf bifurcation and the stability of periodic solutions are obtained using the normal form and the center manifold theory. Furthermore, our main results are illustrated using numerical simulations.

Dynamical analysis of tumor-immune-help T cells system

2019 ◽  
Vol 12 (07) ◽  
pp. 1950075
Author(s):  
Huixia Li ◽  
Shaoli Wang ◽  
Fei Xu
Keyword(s):  
T Cells ◽  
Steady State ◽  
Hopf Bifurcation ◽  
Tumor Cells ◽  
Tumor Antigens ◽  
Critical Value ◽  
Helper T Cells ◽  
Dynamical Analysis ◽  
Bistable Behavior ◽  
The Stability

In this paper, we construct a mathematical model to investigate the interaction between the tumor cells, the immune cells and the helper T cells (HTCs). We perform mathematical analysis to reveal the stability of the equilibria of the model. In our model, the HTCs are stimulated by the identification of the presence of tumor antigens. Our investigation implies that the presence of tumor antigens may inhibit the existence of high steady state of tumor cells, which leads to the elimination of the bistable behavior of the tumor-immune system, i.e. the equilibrium corresponding to the high steady state of tumor cells is destabilized. Choosing immune intensity [Formula: see text] as bifurcation parameter, there exists saddle-node bifurcation. Besides, there exists a critical value [Formula: see text], at which a Hopf bifurcation occurs. The stability and direction of Hopf bifurcation are discussed.

scholarly journals Effect of time delay on a detritus-based ecosystem

2006 ◽  
Vol 2006 ◽  
pp. 1-28 ◽  
Author(s):  
Nurul Huda Gazi ◽  
Malay Bandyopadhyay
Keyword(s):  
Time Delay ◽  
Equilibrium Points ◽  
Equation Model ◽  
Model System ◽  
Trophic Levels ◽  
Dynamical Analysis ◽  
Discrete Time Delay ◽  
Growth Equations ◽  
The Stability ◽  
Delay Differential

Models of detritus-based ecosystems with delay have received a great deal of attention for the last few decades. This paper deals with the dynamical analysis of a nonlinear model of a detritus-based ecosystem involving detritivores and predator of detritivores. We have obtained the criteria for local stability of various equilibrium points and persistence of the model system. Next, we have introduced discrete time delay due to recycling of dead organic matters and gestation of nutrients to the growth equations of various trophic levels. With delay differential equation model system we have studied the effect of time delay on the stability behaviour. Next, we have obtained an estimate for the length of time delay to preserve the stability of the model system. Finally, the existence of Hopf-bifurcating small amplitude periodic solutions is derived by considering time delay as a bifurcation parameter.

scholarly journals Hopf Bifurcation for a Model of HIV Infection ofCD4+T Cells with Virus Released Delay

2011 ◽  
Vol 2011 ◽  
pp. 1-24
Author(s):  
Jun-Yuan Yang ◽  
Xiao-Yan Wang ◽  
Xue-Zhi Li
Keyword(s):  
T Cells ◽  
Hopf Bifurcation ◽  
Hiv Infection ◽  
Numerical Simulations ◽  
Period Solution ◽  
The Stability

A viral model of HIV infection ofCD4+T-cells with virus released period is formulated, and the effect of this released period on the stability of the equilibria is investigated. It is shown that the introduction of the viral released period can destabilize the system, and the period solution may arise. The direction and stability of the Hopf bifurcation are also discussed. Numerical simulations are presented to illustrate the results.

STABILITY AND HOPF BIFURCATION OF A DELAY DIFFERENTIAL SYSTEM IN MICROBIAL CONTINUOUS CULTURE

2009 ◽  
Vol 02 (03) ◽  
pp. 321-328 ◽  
Author(s):  
XIAOFANG LI ◽  
RONGNING QU ◽  
ENMIN FENG
Keyword(s):  
Hopf Bifurcation ◽  
Continuous Culture ◽  
Differential System ◽  
Center Manifold ◽  
Continuous Fermentation ◽  
Transversality Condition ◽  
Discrete Time Delay ◽  
Delay Differential System ◽  
The Stability ◽  
Delay Differential

Introducing discrete time delay into the model for producing 1, 3-propanediol by microbial continuous fermentation, the stability and Hopf bifurcation of a delay differential system for microorganisms in continuous culture are considered in this paper, including the changing regularity of bifurcation value and oscillating period. Algebraic criteria for absolute stability, as well as the transversality condition for Hopf bifurcation of this kind system are obtained. Explicit algorithm for determining the direction of Hopf bifurcation and the stability of periodic solution is derived, using the theory of normal form and center manifold. Finally, numerical simulations show the effectiveness of our results. The pictures of periodic solutions and phase planes with specified parameters suggest that our results can qualitatively describe oscillatory phenomena occurring in experiments.

scholarly journals The Notion of Stability of a Differential Equation and Delay Differential Equation Model of HIV Infection of CD4+ T-Cells

2021 ◽  
Vol 15 ◽  
pp. 20-23
Author(s):  
Normah Maan ◽  
Izaz Ullah Khan ◽  
Nor Atirah Izzah Zulkefli
Keyword(s):  
Differential Equation ◽  
T Cells ◽  
Hiv Infection ◽  
Cd4 T Cells ◽  
Reproduction Number ◽  
Reproduction Rate ◽  
Ode Model ◽  
The Stability ◽  
Delay Differential ◽  
Stability Limits

This research presents a deep insight to address the notion of stability of an epidemical model of the HIV infection of CD4+ T-Cells. Initially, the stability of an ordinary differential equation (ODE) model is studied. This is followed by studying a delay differential equation (DDE) model the HIV infection of CD4+ T-Cells. The available literature on the stability analysis of the ODE model and the DDE model of the CD4+ T-Cells shows that the stability of the models depends on the basic reproduction number “R0”. Accordingly, for the basic reproduction number R0 <1, the model is asymptotically stable, whereas, for R0 >1, the models are globally stable. This research further studies the stability of the models and address the lower possible stability limits for the infection rate of CD4+ T-Cells with virus and the reproduction rate of infectious CD4+ T-Cells, respectively. Accordingly, the results shows that the lower possible limits for the infection rate of CD4+ T-Cells with virus are 0.0000027 mm-3 and 0.000066 mm-3 for the ODE and DDE models, respectively. Again, the lower stability limits for the reproduction rate of infectious CD4+ T-Cells with virus are 12 mm3day-1 and 273.4 mm3day-1 for the ODE and DDE models, respectively. The research minutely studies the stability of the models and gives a deep insight of the stability of the ODE and DDE models of the HIV infection of CD4+ T-Cells with virus.

Sign in / Sign up

Export Citation Format

Share Document