Soliton ratchets out of point-like inhomogeneities L. Morales-Molina, F. G. Mertens and A. Sánchez Eur. Phys. J. B, 37 1 (2004) 79-83 Published online: 19 February 2004 DOI: 10.1140/epjb/e2004-00031-3