Joining those five luminaries are Ellen V. Futter , president of the American Museum of Natural History in New York ; Carla A . Hills , former United States trade representative ; Frank J. Hoenemeyer , retired vice chairman of the Prudential Insurance Company of America ; Richard C. Holbrooke , former ambassador to the United Nations ; and Frank G. Zarb , former chairman of the Nasdaq stock market and senior adviser to Hellman & Friedman , a private investment firm .