1. Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
2. Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo naḿesti 542/2, 16610 Prague, Czech Republic
3. Computational Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
4. MEMPHYS-Center for Biomembrane Physics