
Secretary of State Hillary Rodham Clinton delivers her speech on "Internet Rights And Wrongs: Choices & Challenges In A Networked World" Tuesday, Feb. 15, 2011, at George Washington University in Washington. (AP Photo/Manuel Balce Ceneta)

Health and Human Services Secretary Kathleen Sebelius and Agriculture Secretary Tom Vilsack announce new dietary guidelines at George Washington University in Washington, D.C., on Monday to help Americans make healthier food choices and confront the obesity epidemic. (Associated Press)

Health and Human Services Secretary Kathleen Sebelius and Agriculture Secretary Tom Vilsack announce new dietary guidelines to help Americans make healthier food choices and confront the obesity epidemic at George Washington University in Washington, D.C., on Monday. (Associated Press)

Health and Human Services Secretary Kathleen Sebelius,left, and Agriculture Tom Vilsack, take part in a press conference at George Washington University in Washington, Monday, Jan. 31, 2011, announcing new dietary guidelines to help Americans make healthier food choices and confront obesity epidemic. (AP Photo/Manuel Balce Ceneta)

**FILE** In this April 21, 2008, file photo, Professor Stephen Hawking of the University of Cambridge makes remarks at an event marking the 50th anniversary of NASA, at George Washington University in Washington. (Associated Press)