  Associated to any finite flag complex L there is a right-angled Coxeter group
W_L and a contractible cubical complex Sigma_L (the Davis complex) on which W_L
acts properly and cocompactly, and such that the link of each vertex is L. It
follows that if L is a generalized homology sphere, then Sigma_L is a
contractible homology manifold. We prove a generalized version of the Singer
Conjecture (on the vanishing of the reduced weighted L^2_q-cohomology above the
middle dimension) for the right-angled Coxeter groups based on barycentric
subdivisions in even dimensions. We also prove this conjecture for the groups
based on the barycentric subdivision of the boundary complex of a simplex.
