Affiliation: | 1. Department of Physics, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaoundé Cameroon2. Department of Physics, Higher Teachers’ Training College, University of Maroua, P.O. Box 55, Maroua, Cameroon3. National Advanced School of Engineering, University of Yaoundé I, P.O. Box 8390, Yaoundé Cameroon4. The Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Strasse 38, 01187 Dresden, Germany |