1. a Deutsche Telekom Laboratories , Berlin University of Technology , Ernst-Reuter-Platz 7, 10587, Berlin, Germany
2. b Department of Anatomy , University of Cologne , Joseph-Stelzmann-Strasse 9, 50931, Cologne, Germany
3. c German Aerospace Center, Institute of Transportation Systems , Lilienthalplatz 7, 38108, Braunschweig, Germany
4. d DaimlerChrysler AG, Customer Research Center , Leibnizstr. 2, 71032, Böblingen, Germany