I am profoundly grateful to my supervisor, Prof. Fábio Maia Bertato, for believing in my academic potential, for providing me many opportunities, and for the support, guidance, and mentoring, not only in academic matters, but in many other subjects of life. Prof. Itala D'Ottaviano, who was my supervisor in the beginning of this research and has always supported it in a number of ways along the years, has also my sincere gratitude. I would like to thank