There are several people who have been an inspiration to me during the challenging
times of the Ph.D. program. I’d like to dedicate this dissertation to:
Sophia Iantcheva (my grandmother), who has taught me the value of staying
optimistic in the face of great challenges.
Nina Marinova (my mother), for her unswerving belief in me.
Ivan Anastassov (my husband), for his selfless encouragement and support.
Krustio Krustev, for being a great inspiration to me.