Infinitely many radial solutions to a boundary value problem in a ball

In this paper we are concerned with the existence and multiplicity of radial solutions to the BVP B is an open ball in ?^K and u??·(a(|?u|)?u) is a nonlinear differential operator (e.g. the plaplacian or the mean curvature operator). The function f is defined in a neighborhood of u=0 and satisfies a «sublinear»-type growth condition for u→0. We use a degree approach combined with a time-map technique. Multiplicity results are obtained also for nonlinearities of concave-convex type.