This manuscript would not have come to an end without the support of certain people. Foremost, I would like to express my deep gratitude to my PhD supervisors Prof. Ismene Gizelis and Prof. Kristian Gleditsch for the continuous support, motivation and patience during my PhD. They have been great advisors in my research career and personal life. Exceptional thanks go to Kaisa Hinkkainen for hours of brainstorming, Sebastian Ziaja for dispassionate advice, Vincenzo Bove for his positive energy and Tobias Böhmelt for setting higher standards!
I could not leave outside from this part of my life my best friends, from home, that they made everything possible to diminish the long distance. Last but not the least; I would like to thank my parents Zoe and Stratos for their financial and moral support in every single step of my life. I am really sorry for being far away from you! And special thanks go to my brother too, Michalis, who likes challenging me to make me brave and confident.