Affiliation: | a African Institute for Mathematical Sciences (AIMS), 6 Melrose Road, Muizenberg 7945, South Africa b Max-Planck-Institut für Physik Komplexer Systeme, Nöthnitzer Str. 38, D-01187 Dresden, Germany c Laboratory of Modelling and Simulation in Engineering and Biological Physics, University of Yaoundé I, P.O. Box 812, Yaoundé, Cameroon |