(1) The Secretary may prescribe regulations establishing conditions under which officers and employees of the Administration who are nationally recognized principal investigators in medical research may be permitted to accept payment, in cash or in kind, from non-Federal agencies, organizations, and individuals for travel and such reasonable subsistence expenses as are approved by the Secretary pursuant to such regulations
(A) in connection with their attendance at meetings or in performing advisory services concerned with the functions or activities of the Department; or
(B) in connection with acceptance of significant awards or with activity related thereto concerned with functions or activities of the Department.