The Energy Density of "Wound" Fields in a Toroidal Universe
  The observational limits on the present energy density of the Universe allow for a component that redshifts like $1/a^2$ and can contribute significantly to the total. We show that a possible origin for such a contribution is that the universe has a toroidal topology with "wound" scalar fields around its cycles. 
W. Fischler, S. Paban and M. Zanic