A thesis was a long essay written by a student-candidate for a degree. The essay was based on the personal research of the student.
In the mid-2260s, the subject of Elizabeth Dehner's thesis was the testing and studying of esper-oriented beings. She published her thesis in association with the College of Medical Sciences, a medical school of the Tri-Planetary Academy. This thesis was cited in her personnel records as the reason for her posting to the Aldebaron colony. (TOS: "Where No Man Has Gone Before")
In the mid-24th century, Leah Brahms wrote two theses, "Subspace Processing Modes in Warp Propulsion Applications", for her Master of Cybernetics, and "Higher Order Warp Field Propulsion Applications", for her Doctor of Theoretical Physics. These theses were mentioned on her biographical data file. (TNG: "Booby Trap", okudagram)
In 2365, Sonya Gomez wrote a graduating thesis for Starfleet Academy. After reading her thesis, Chief Engineer Geordi La Forge requested that she be assigned to his ship, the USS Enterprise-D. (TNG: "Q Who")
In 2369, Doctor Mizan, posing as a student at a psychological conference on long-term deep space assignments, approached Deanna Troi. He said that he was writing a thesis on inter-species mating rituals and asked her if she would like to join with him on empirical research. Knowing who he was, she said no. (TNG: "Timescape")