To continue to be eligible for a fellowship, a fellow must—

(a) Maintain satisfactory progress in the program for which the fellowship was awarded;

(b) Devote essentially full time to study or research in the academic field in which the fellowship was awarded; and

(c) Not engage in gainful employment, except on a part-time basis in teaching, research, or similar activities determined by the academic department to be in support of the fellow's progress toward a degree.