Cosmology with Two Compactification Scales

We consider a (4 + d)-dimensional spacetime broken up into a (4 - n)-dimensional Minkowski spacetime (where n goes from 1 to 3) and a compact (n + d)-dimensional manifold. At the present time the n compactification radii are of the order of the Universe size, while the other d compactification radii are of the order of the Planck length.