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Extending the results of a previous paper on the relationship between fish consumption and coronary heart disease, an optimal control approach is proposed in the present paper. The Pontryagin's minimum principle is used to characterize the optimal control, to minimize the population of susceptible individuals and also to reduce the mortality rate of coronary heart disease. A numerical simulation is carried out to show the impact of the proposed optimal control. Indeed, the model shows that the prevalence and mortality of coronary heart disease can be significantly reduced in a period of 10 years. [ABSTRACT FROM AUTHOR]

In this paper, we consider a kind of delayed Schoener's competition model with harvesting terms and impulsive effects. By means of Mawhin's continuation theorem of coincidence degree theory, some sufficient conditions are obtained for the existence of at least four positive almost periodic solutions for the above model. Further, by using the comparison theorem and constructing a suitable Lyapunov functional, the global asymptotic stability of the model is also investigated. To the best of the author's knowledge, sofar, the results of this paper are completely new. An example and numerical simulations are employed to illustrate the main results in this paper. [ABSTRACT FROM AUTHOR]