This prohibition, however, does not forbid a faculty member while on leave from giving a limited number of lectures or doing a limited amount of work. Nor does this prohibition forbid the acceptance by a faculty member, while on leave, of a scholarship or fellowship carrying a stipend for the purpose of study, research, or scientific investigation, or the acceptance of a grant of money made for such purposes, provided that the acceptance of the grant does not impose on the recipient duties and obligations that are incompatible with the general purpose for which leaves of absence are granted.