Remarks on contractions of reaction-diffusion PDE's on weighted L^2 norms

In [1], we showed contractivity of reaction-diffusion PDE: \frac{\partial u}{\partial t}(ω,t) = F(u(ω,t)) + DΔu(ω,t) with Neumann boundary condition, provided μ_{p,Q}(J_F (u)) < 0 (uniformly on u), for some 1 \leq p \leq \infty and some positive, diagonal matrix Q, where J_F is the Jacobian matrix of F. This note extends the result for Q weighted L_2 norms, where Q is a positive, symmetric (not merely diagonal) matrix and Q^2D+DQ^2>0.