Abstract. We study the existence of positive solutions of the equation u" + a{t)f{u) = 0 with linear boundary conditions. We show the existence of at least one positive solution if / is either superlinear or sublinear by a simple application of a Fixed Point Theorem in cones.

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Abstract. We study the existence of positive solutions of the equation u" + a{t)f{u) = 0 with linear boundary conditions. We show the existence of at least one positive solution if / is either superlinear or sublinear by a simple application of a Fixed Point Theorem in cones.

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This paper establishes some maximum and comparison principles relative to lower and upper solutions of nonlinear parabolic partial differential equations with impulsive effects. These principles are applied to obtain some sufficient conditions for the global asymptotic stability of a unique positive equilibrium in a reactiondiffusion equation modeling the growth of a single-species population subject to abrupt changes of certain important system parameters.

Abstract. In this paper, we consider the second-order nonlinear delay dynamic equation

We establish a new Pohozaev-type identity and use it to prove a theorem on the uniqueness of positive radial solutions to the quasilinear elliptic problem div( |{u| m&2 {u)+ f (u)=0 in B, and u=0 on B, where B is a finite ball in R n , n 3 and 10 and 1 p