Eva Moreno-galbis GRANEM, GAINS-TEPP   13 allee Francois Mitterrand Angers, 49000 FRANCE   eva.morenogalbis@univ-angers.fr   http://perso.univ-lemans.fr/~emoreno/           JEL Areas: J2 : Demand and Suppply of Labor: General O3 : Technological Change; Research and Development: General