First Author:   Therese Rebière LIRSA-CNAM and IZA therese.rebiere@cnam.fr   Department of Economics (EFAB), CNAM, case 1D2P30, 40, rue des Jeûneurs Paris, 75002, FRANCE   +33 1 40 27 26 42(Phone) +33 1 40 27 26 42(Fax) http://economics.rebiere.free.fr/