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In this paper, we consider a Hastings–Powell type model, which consists of a three-species food chain model with fear effect. For more realistic formulation, we incorporated two time delays into the model, one for prey density another for the gestation of the middle and top predator populations. By choosing time delays as the bifurcation parameters, the essential mathematical features and their dynamics are studied in terms of local stability and Hopf bifurcation analysis. Linearizing the system at the positive equilibrium point and analyzing the distribution of the roots of the associated characteristic equation, the conditions for the existence of Hopf bifurcation are obtained. It is shown that for the gradual increase of the magnitude of delay, the stability of equilibrium point changes and the system exhibits a Hopf bifurcation as the time delay passes through some critical values. Furthermore, an explicit formula for determining the direction of the Hopf bifurcation and the stability of the bifurcating periodic orbits are investigated by using the normal form method and center manifold theory. Finally, several numerical simulations are provided to verify the effectiveness of the derived theoretical results and to examine the analytical findings. [ABSTRACT FROM AUTHOR]

• The three-strategy game model with continuous distributed time delay is analyzed. • The two-community three-strategy games with two delays is discussed. • The existence of Hopf bifurcation in replicator equation is proved. • The rock-paper-scissors game is simulated as an example. In this paper, we combine evolutionary game with dynamics, and discuss two kinds of game models with time delay. First, based on continuous distributed (kernel function) stochastic delay, we give the asymptotic stability condition of general three-strategy game model. Second, we study the replicator dynamics of two-community three-strategy game model with two fixed time delays (i.e. τ 1 within the community and τ 2 between different communities). Based on Hopf bifurcation theory, by calculating the critical conditions for the existence of bifurcation, the influence of bifurcation on the stability of equilibrium points is analyzed. Finally, we take rock-paper-scissors game as an example to verify the correctness of the theoretical results, when the delay τ meets certain conditions or doesn't exceed the critical value, the stability of the system will not change. [ABSTRACT FROM AUTHOR]

In this paper, a mathematical model with time-delay-related parameters and media coverage to describe the diffusion process of new products is proposed, in which the time-delay-related parameters denote the stage in which potential customers decide whether to adopt a new product. Then, the stability and the Hopf bifurcation of the proposed model are analyzed in detail. The center manifold theorem and the normal form theory are used to investigate the stability of the bifurcating periodic solution. Moreover, a numerical simulation is conducted to investigate the difference between the model with delay-dependent parameters and that with delay-independent parameters. The results show that there is significant difference between the two models. [ABSTRACT FROM AUTHOR]

Ecological stoichiometry is the study of the balance of multiple elements in ecological interactions and processes (Sterner and Elser in Ecological Stoichiometry: The Biology of Elements from Molecules to the Biosphere, 2002). Modeling under this framework enables us to investigate the effect nutrient content on organisms whether the imbalance involves insufficient or excess nutrient content. This phenomenon is called the "stoichiometric knife-edge". In this paper, a discrete-time predator–prey model that captures this phenomenon is established and qualitatively analyzed. We systematically expound the similarities and differences between our discrete model and the corresponding continuous analog. Theoretical and numerical analyses show that while the discrete and continuous models share many properties, differences also exist. Under certain parameter sets, the models exhibit qualitatively different dynamics. While the continuous model shows limit cycle, Hopf bifurcation, and saddle-node bifurcation, the discrete-time model exhibits richer dynamical behaviors, such as chaos. By comparing the dynamics of the continuous and discrete model, we can conclude that stoichiometric effects of low food quality on predators are robust to the discretization of time. This study can possibly serve as an example for pointing to the importance of time scale in ecological modeling. [ABSTRACT FROM AUTHOR]

Despite advanced discoveries in cancerology, conventional treatments by surgery, chemotherapy, or radiotherapy remain ineffective in some situations. Oncolytic virotherapy, i.e., the involvement of replicative viruses targeting specific tumor cells, opens new perspectives for better management of this disease. Certain viruses naturally have a preferential tropism for the tumor cells; others are genetically modifiable to present such properties, as the lytic cycle virus, which is a process that represents a vital role in oncolytic virotherapy. In the present paper, we present a mathematical model for the dynamics of oncolytic virotherapy that incorporates multiple time delays representing the multiple time periods of a lytic cycle. We compute the basic reproductive ratio R0, and we show that there exist a disease-free equilibrium point (DFE) and an endemic equilibrium point (DEE). By formulating suitable Lyapunov function, we prove that the disease-free equilibrium (DFE) is globally asymptotically stable if R0<1 and unstable otherwise. We also demonstrate that under additional conditions, the endemic equilibrium is stable. Also, a Hopf bifurcation analysis of our dynamic system is used to understand how solutions and their stability change as system parameters change in the case of a positive delay. To illustrate the effectiveness of our theoretical results, we give numerical simulations for several scenarios. [ABSTRACT FROM AUTHOR]