Science Advisor to the President Science Advisor to the President The Science Advisor to the President is an individual charged with providing advisory opinions and analysis on science and technology matters to the President of the United States. The first Science Advisor, Vannevar Bush, chairman of the Office of Scientific Research and Development, served Presidents Franklin Delano Roosevelt and Harry S. Truman from 1941 to 1951. President Truman created the President's Science Advisory Committee in 1951, establishing the chairman of this committee as the President's Science Advisor. This committee continued under Presidents Dwight D. Eisenhower, John F. Kennedy, Lyndon B. Johnson, and Richard M. Nixon
President of Ukraine by acting president Oleksandr Turchynov, who then also served as Chairman of the Ukrainian Parliament, on 21 February 2014. Oleksandr Turchynov was the only acting president in Ukraine's modern history. Unlike in the US, where the vice president immediately receives all powers of the presidency upon assumption of the presidential office, in Ukraine the powers of an acting president are severely limited. On 18 June 2015, Yanukovych was officially deprived of the title of president of Ukraine. The current president is Petro Poroshenko who took the oath of office on 7 June 2014. The Government of Ukraine utilizes a Semi-presidential