1. Department of Psychiatry and Psychotherapy, Bezirksklinikum, University of Regensburg, Universitätsstraße 84, 93053 Regensburg, Germany
2. Department of Mathematics, University of Bergen, 5020 Bergen, Norway
3. Department of Epidemiology and Preventive Medicine, University of Regensburg, 93053 Regensburg, Germany
4. Department of Otorhinolaryngology, University of Regensburg, 93053 Regensburg, Germany