1. CNRS-ENSCP-PARIS6, 4, Pl. Jussieu, 75252 Paris Cedex 05, France, Department of Physical Chemistry, University of Pannonia, H-8201 Veszprém, P.O. Box 158, Hungary, Institute for Condensed Matter Physics, National Academy of Ukraine, 1 Svientsitskii Str., 79011 Lviv, Ukraine, and Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, Illinois 60612