; (bb) physics; (cc) chemistry; (dd) biology; (ee) engineering; (ff) economics; (gg) business management; and (hh) such other disciplines as the Administrator determines to be necessary to achieve the purposes of this subparagraph. (III) Term; vacancies (aa) Term A member of the Board shall serve for a term of 6 years. (bb) Vacancies A vacancy on the Board— (AA) shall not affect the powers of the Board