1. Physikalisches Institut, University of Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany
2. Institute for Hygiene, University of Münster, Robert-Koch-Str. 41, 48149 Münster, Germany and Interdisciplinary Center for Clinical Research (IZKF), University of Münster, Domagkstr. 3, 48149 Münster, Germany