service which is performed by a nonresident alien individual for the period he is temporarily present in the United States as a nonimmigrant under subparagraph (F), (J), (M), or (Q) of section 101(a)(15) of the Immigration and Nationality Act, as amended ( 8 U.S.C. 1101(a)(15)(F) , (J), (M), or (Q)), and which is performed to carry out the purpose specified in subparagraph (F), (J), (M), or (Q), as the case may be;