First Author:   Fábio A. R. Gomes University of São Paulo, Department of Economics, FEA-RP fabiogomes@fearp.usp.br   Av. Bandeirantes 3900, Monte Alegre Ribeirão Preto, 14040-905, Brazil   55 (16) 99770-6419(Phone) 55 (16) 99770-6419(Fax)