1The Holm Group, Biocenter II, Institute of Biotechnology, PO Box 56, 00014 University of Helsinki, Finland 2Finnish Red Cross Blood Service Research and Development, Kivihaantie 7, 00310 Helsinki, Finland 3Department of Mathematics and Statistics, P.O. Box 68, 00014 University of Helsinki, Finland 4Department of Biological and Environmental Sciences, P.O. Box 56, 00014 University of Helsinki, ...