First Author:   Youssouf Kiendrebeogo CERDI, University of Auvergne youssouf.kiendrebeogo@udamail.fr   65 Boulevard François Mitterrand, BP 320 Clermont-Ferrand, 63009, France   +33(0)473177438(Phone) +33(0)473177438(Fax) http://cerdi.org/