A complement to the Fredholm theory of elliptic systems on bounded domains.
We consider a homogeneous elliptic Dirichlet problem involving an Ornstein-Uhlenbeck operator in a half space of . We show that for a particular initial datum, which is Lipschitz continuous and bounded on , the second derivative of the classical solution is not uniformly continuous on . In particular this implies that the well known maximal Hölder-regularity results fail in general for Dirichlet problems in unbounded domains involving unbounded coefficients.
The celebrated criterion of Petrowsky for the regularity of the latest boundary point, originally formulated for the heat equation, is extended to the so-called p-parabolic equation. A barrier is constructed by the aid of the Barenblatt solution.
We consider the equation , where is a first order pseudo-differential operator with real symbol . Under a suitable convexity assumption on we find the decay properties for . These can be applied to the linear Maxwell system in anisotropic media and to the nonlinear Cauchy Problem , . If is a smooth function which satisfies near , and is small in suitably Sobolev norm, we prove global existence theorems provided is greater than a critical exponent.
We study a singular perturbation problem arising in the scalar two-phase field model. Given a sequence of functions with a uniform bound on the surface energy, assume the Sobolev norms of the associated chemical potential fields are bounded uniformly, where and is the dimension of the domain. We show that the limit interface as tends to zero is an integral varifold with a sharp integrability condition on the mean curvature.