Attractors for reaction-diffusion equations on arbitrary unbounded domains

We prove existence of global attractors for parabolic equations of the form $$u_t+\beta(x)u-\sum_{ij}\partial_i(a_{ij}(x)\partial_j u)=f(x,u)$$ with Dirichlet boundary condition on an arbitrary unbounded domain $\Omega$ in $\R^3$, without smoothness assumptions on $a_{ij}(\cdot)$ and $\partial\Omega$.