Damping and frequency shift in the oscillations of two colliding Bose-Einstein condensates M. Modugno, C. Fort, P. Maddaloni, F. Minardi and M. Inguscio Eur. Phys. J. D, 17 3 (2001) 345-349 Published online: 15 December 2001 DOI: 10.1007/s100530170009