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This paper is concerned with the periodic solutions for a class of new Nicholson-type delay system with nonlinear density-dependent mortality terms. By using coincidence degree theory, some criteria are obtained to guarantee the existence of positive periodic solutions of the model. Moreover, an example is employed to illustrate the main results. [ABSTRACT FROM AUTHOR]

In this paper, by using Mawhin's continuation theorem of coincidence degree theory, sufficient conditions for the existence of positive almost periodic solutions are obtained for the predator-prey Lotka-Volterra competition system with delays {dui(t)/dt = ui(t)[ai(t) - ... ail(t)ul(t - σil(t)) - ... bij(t)vj(t - τij(t))], i = 1,..., n, {dvj(t)/dt = vj(t) [ - rj(t) + ... djl(t)ul(t)ul(t - δjl(t)) - ... ejh(t)vh(t - ϑjh(t))], j = 1,..., m, where ai, rj, ail, bij, djl, ejh ∈ C (ℝ, (0, ∞)), σil, τij, δjl, ϑjh, ∈ c (ℝ, ℝ) (i, l = 1,..., n, j, h = l,..., m) are almost periodic functions. [ABSTRACT FROM AUTHOR]

This paper is concerned with a class of Nicholson's blowflies models with a nonlinear density-dependent mortality term. We use coincidence degree theory and give several sufficient conditions which guarantee the existence of positive periodic solutions of the model. Moreover, we give an example to illustrate our main results. [ABSTRACT FROM AUTHOR]

This paper is concerned with a class of Nicholson's blowflies model with a linear harvesting term. By applying the method of coincidence degree, some criteria are established for the existence and uniqueness of positive periodic solutions of the model. Moreover, an example is employed to illustrate the main results. [ABSTRACT FROM AUTHOR]

In this paper, the following fractional order ordinary differential equation boundary value problem: D0α+u(t) = f(t, u(t),D0+α-1 u(t)) + e(t), 0 < t < 1, I0+2-α u(t) |t=0= 0, D0+α-1 u(1) = Σi=1m-2 βiD0+α-1u(ηi), is considered, where 1 < α ≤ 2, is a real number, D0+α and I0+α are the standard Riemann-Liouville differentiation and integration, and ƒ : [0, 1] x R2 → R is continuous and e ∈ L¹[0, 1], and ηi ∈ (0, 1), βi ∈ R, i = 1, 2, ⋯ ,m - 2, are given constants such that Σi=1m-2 βi = 1. By using the coincidence degree theory, some existence results of solutions are established. [ABSTRACT FROM AUTHOR]

In this paper, the stability and existence of periodic solutions for an unidirectionally coupled nonlinear system with delays are investigated by combining the linear stability theory and the embedding technique of asymptotically autonomous semiflows, Hopf bifurcation theory and a continuation theorem of coincidence degree theory, respectively. Some numerical simulations are carried out for illustrating the analytical results.

This paper is concerned with a class of Nicholson's blowflies model with a linear harvesting term. By applying the method of coincidence degree, some criteria are established for the existence and uniqueness of positive periodic solutions of the model. Moreover, an example is employed to illustrate the main results.

In this paper, a delay model of plankton allelopathy is investigated. By using the coincidence degree theory, sufficient conditions for existence of periodic solutions are obtained. The presented criteria improve and extend previous results in the literature.