TITLE: Stable boundary layers in a diffusion problem with nonlinear reaction at the boundary AUTHORS: Jos{\'e} M. Arrieta, Neus C{\'o}nsul and An{\'\i}bal Rodr{\'\i}guez-Bernal ABSTRACT: We prove the existence of nonconstant stable stationary solutions of an evolution problem with a nonlinear reaction acting on the boundary. These solutions present layers at certain points of the boundary. We also study the behavior of these solutions as the small parameter appearing in the equation approaches zero and show some stability properties of the profiles given by these equilibrium solutions. 2000 Mathematics Subject Classification: Primary 37L15; Secondary 35K57 Keywords: boundary reaction, patterns, boundary layers, energy, minimizers, stability