First Author:   Francis BLOCH GREQAM, Ecole Superieure de Mecanique de Marseille bloch@ehess.cnrs-mrs.fr   GREQAM, Centre de la Vieille Charite, 2 rue de la Charite Marseille, 13002   France(Phone) France(Fax) Second Author: Vijayendra RAO Development Research Group, The World Bank vrao@worldbank.org   The World Bank, 1818 H Street NW Washington, 20433, USA   202 458 8034(Phone) 202 522 1153(Fax)