WMAP5 constraints on the unified model of dark energy and dark matter
  We derive constraints on the parameter space of the unified model of dark energy and dark matter, the Generalized Chaplygin Gas (GCG), from the amplitudes and positions of the first few peaks and first trough of the cosmic microwave background radiation (CMBR) power spectrum, using the latest WMAP five year data. 
T. Barreiro, O. Bertolami and P. Torres