List of Tables List of Figures List of BoxesList of Maps Acknowledgements viii ix ix ix x"Caminante no hay camino, se hace camino al andar", By Antonio Machado from one of his poems with the same title. Although I had read the poem many years ago, while I was working on this dissertation it came back to my mind after reading a paper by Arie Rip and other scholars who quoted it. Since reading the quote, it has been on my mind resonating with my past, present and future. Today, looking back at this journey, a mixture of feelings emerges, but most of all a feeling of gratitude for a path travelled over the last four years. Like a captain discovering the world, I feel happy and proud for arriving safely at my destination port with my crew. However, I also feel nostalgic about the adventures we experienced together along the way, as the path we sealed across will never be crossed again, but the memories will remain.Navigating the ocean of knowledge is a risky adventure, even more in the darkest nights when the clouds reduce the visibility of the celestial bodies to navigate. In such circumstances, lighthouses are sources of hope to find or rectify the course. In my research process, I always had two shining lighthouses to guide my navigation. Thank you, Professors Stefan and Gonzalo, for lighting my path, by listening to my questions and supporting me through the challenging decisions I made. Thank you for teaching me how to sail my PhD.I have the best crew in the world. My wife, María, has been my inspiration, my support, my advisor, my "partner-in-crime", and my encouragement to navigate the dark days of this research. My beloved son, Gael, who is now my powerful raison d'etre in this project and of our future adventures together. Finally, my parents, Maricela and Manuel, were always there. They gave me the foundations to sail my paths. Thank you also to my brother, who has always been my sparring partner to help me understand life from a different perspective, and to my grandmother and my uncle.