First Author:   Luiz Carlos de S. Ribeiro Universidade Federal de Sergipe, Sergipe, Brazil. ribeiro.luiz84@gmail.com         Second Author: Gervásio F. Santos Federal University of Bahia, Brazil gervasiofsantos@gmail.com         Third Author: Rodrigo B. Cerqueira Superintendence of Economic and Social Studies of Bahia (SEI), Salvador, Brazil rbcerqueira@gmail.com         Fourth Author: Kênia B. Souza Federal University of Paraná, Brazil keniadesouza@gmail.com