accepting me as a Ph.D. student and creating the ideal academic atmosphere for the development of this project.• My parents, Ernesto and Marilene. I would never have imagined that their constant feeding of my curiosity would lead me so far.• The Central Bank of Brazil, for providing me a relief from my professional duties and the financial support, which without I could not have carried out this project.• The following colleagues who, each in their own way, collaborated with me on this project: