for official reception and representation expenses. Science and technology directorate Operations and support For necessary expenses of the Science and Technology Directorate for operations and support, including the purchase or lease of not to exceed 5 vehicles, $254,618,000, of which $134,795,000 shall remain available until September 30, 2019: Provided , That not to exceed $7,650 shall be for official reception and representation expenses. Research and development For necessary expenses of the Science and Technology Directorate for research and development, $383,482,000, to remain available until September 30, 2020. Domestic nuclear detection office Operations and support For necessary expenses of the Domestic Nuclear Detection Office for operations and support, $54,664,000: Provided , That not to exceed $2,250 shall be for official reception and representation expenses. Procurement, construction, and improvements For necessary expenses of the Domestic Nuclear Detection Office for procurement, construction, and improvements, $87,096,000, to remain available until September 30, 2020. Research and development For necessary expenses of the Domestic Nuclear Detection Office for research and development, $144,161,000, to remain available until September 30, 2020. Federal assistance For necessary expenses of the Domestic Nuclear Detection Office for Federal assistance through grants, contracts, cooperative agreements, and other activities, $44,519,000, to remain available until September 30, 2020. Administrative provisions 401. Notwithstanding any other provision of law, funds otherwise made available to U.S. Citizenship and Immigration Services may be used to acquire, operate, equip, and dispose of up to 5 vehicles, for replacement only, for areas where the Administrator of General Services does not provide vehicles for lease: Provided , That the Director of U.S. Citizenship and Immigration Services may authorize employees who are assigned to those areas to use such vehicles to travel between the employees'