First Author:   Flavio V. Vieira Institute of Economics, Federal University of Uberlandia and CNPq Associate Researcher, Brazil flaviovieira@ufu.br   Instituto de Economia, Instituto de Economia, Universidade Federal de Uberlandia Uberlandia, 38400902, Brasil   +553432162585(Phone) +553432162585(Fax) http://www.ie.ufu.br Second Author: Cleomar Gomes da silva Institute of Economics, Federal University of Uberlandia and CNPq Associate Researcher, Brazil cleomargomes@ufu.br   Av Joao Naves de Avila 2121, Instituto de Economia, Universidade Federal de Uberlandia Uberlandia, 38400902, Brazil   +553432394157(Phone)   http://www.ie.ufu.br