I am deeply and extremely grateful to my family, the perfect treasure I have. Each of them well deserves a vast letter of acknowledgements for their contributions, in many senses, to my life. However, for completeness, I would like to mention my mother Rosa, who has always been there for me, my pillar, my brother Jhonatan, for his patience during my journeys, and my father Carlos for his unconditional help. My aunts, Luz, Carmenza, Martha and Amparo, because they have taught me what family and real love are. My cousins and uncles, for all the cheering up and good mood. I would also like to specially thank my advisor Gustavo, because his patience with my occurrences has been way way way admirable during this period of doctoral studies that ends, as well as special thanks to my coadvisor Fabricio. Finally, many thanks to my colleagues from the LMACC, so nice people I had the fortune to meet, specially Sabrina, Alfredo, Miguel, Hugo and Larissa. Finally, I gratefully acknowledge the financial support received from São Paulo Research Foundation (FAPESP) under grants #2014/14720-8, #2013/07375-0 (CEPID) and #2016/20115-5 (BEPE). The finishing of this work would not have been possible without this important support. "Si alguna vez me cruzas por la calle Regálame tu beso y no te aflijas Si ves que estoy pensando en otra cosa No es nada malo, es que pasó una brisa La brisa de la muerte enamorada Que ronda como un ángel asesino Mas no te asustes siempre se me pasa Es solo la intuición de mi destino." (Fito Páez, Al lado del camino)