Under very simple conditions, we prove the existence of one positive and one negative solution of an asymptotically linear elliptic boundary value problem. Even for the resonant case at infinity, we do not need to assume any more conditions to ensure the boundness of the (PS) sequence of the corresponding functional. Moreover, the proof is very simple.

We deal with a three point boundary value problem for a class of singular parabolic equations with a weighted integral condition in place of one of standard boundary conditions. We will first establish an a priori estimate in weighted spaces. Then, we prove the existence, uniqueness, and continuous dependence of a strong solution.

We consider a Timoshenko system with memory condition at the boundary and we study the asymptotic behavior of the corresponding solutions. We prove that the energy decay with the same rate of decay of the relaxation functions, that is, the energy decays exponentially when the relaxation functions decays exponentially and polynomially when the relaxation functions decays polynomially.

We study the location of the peaks of solution for the critical growth problem $-{\epsilon }^2\Delta u+u=f\left(u\right)+u^{2^{*}-1}$, $u>0$ in $\Omega$, $u=0$ on $\partial \Omega$, where $\Omega$ is a bounded domain; $2^{*}=2N/\left(N-2\right)$, $N\ge 3$, is the critical Sobolev exponent and $f$ has a behavior like $u^p$, .