First Author:   Sergio Da Silva Department of Economics, University of Brasilia SergioDaSilva@angelfire.com         Second Author: Raul Matsushita Department of Statistics, University of Brasilia raulmta@unb.br         Third Author: Iram Gleria Department of Physics, Catholic University of Brasilia iramgl@bol.com   Department of Physics, Catholic University of Brasilia Taguatinga, 72030-170, Brazil