To end a Ph.D. is like to end a very long trip. A trip where a lot of people cross our paths. People that we are thankful and that have helped us in several manners, both in direct and indirect ways.My special thanks to Silvia Cucatti, my beloved wife, which has been by my side since I started my Master degree. I do not have the words to say how much you help me, how much life is easy and pleasant at your side and how much I'm thankful. I love you! I thank my advisor, Prof. Márcio Menon, for everything. Thank you for the friendship, for the good moments, for the opportunity to work with you. I'll never forget what I have learned with you.The family is the ground where things start to grow. I'll be eternally thankful to my parents, my sister, and relatives for all the support during my life.Good friends are those who stay with us in easy and difficult times. And I can say that I have good friends. I'm thankful to