Physics Department and Research Center OPTIMAS;
Technische Universitat Kaiserslautern;
67663 Kaiserslautern;
Germany;
Departament de Fisica;
Universitat Auto’noma de Barcelona;
E-08193 Bellaterra;
Spain;
Institut fur Physik;
Universitat Rostock;
Albert-Einstein-StraBe 23;
18059 Rostock;
Germany;
Department of Physics and SUPA;
University of Strathclyde;
Glasgow G40NG;
UK;
Fraunhofer Institute for Industrial Mathematics ITWM;
67663 Kaiserslautern;
Germany;