Jose G De lara resende Universidade de Brasilia   Prédio da FACE, UnB Campus Darcy Ribeiro Brasilia, DF 70910-900 Brazil   jglresende@unb.br   https://sites.google.com/site/jglresende/           JEL Areas: O3 : Technological Change; Research and Development: General J1 : Demographic Economics: General