Nik Wallenda pauses to rest during his walk on a high wire that's over 1000 feet long and 200 above the Allegheny River and Roberto Clemente Bridge without his shoes as part of the Three Rivers Regatta in Pittsburgh on July 3, 2009. Wallenda is the seventh generation of the legendary Great Wallendas, who have performed in circus acts since the 1800s. (UPI Photo/Archie Carpenter)

Supporters of Iran's President Mahmoud Ahmadinejad gather for a rally in Tehran, Iran on June 14, 2009. (UPI Photo/Hossein Fatemi)

Green symbols of the G8 summit are seen in L'Aquila, Italy on July 9, 2009. (UPI Photo/Anatoli Zhdanov)

British actress Emma Watson and actors Rupert Grint and Daniel Radcliffe attend the World premiere of "Harry Potter And The Half-Blood Prince" at the Odeon and Empire Cinemas at Leicester Square in London on July 7, 2009. (UPI Photo/Rune Hellestad)

Fans gather to mourn the death of former Tennessee Titans quarterback Steve McNair outside his Gridiron 9 restaurant in Nashville, Tennessee on July 6, 2009. McNair was found dead with several gunshot wounds in a Nashville condominium on Saturday, July 4. (UPI Photo/Frederick Breedon IV)

Tai Shan eyes up his birthday cake at the Smithsonian National Zoological Park in Washington on July 9, 2009. The zoo held an event to celebrate the panda's fourth birthday with a frozen cake made from ice, bamboo, shredded beets and beet juice. (UPI Photo/Kevin Dietsch)

This sign marks the entrance to the Presidental Retreat known as Camp David located in the Catctin Mountains in Maryland 11/30/1972.

President Barack Obama talks about alternative energy at the Trinity Structural Towers plant in Newton, Iowa on April 22, 2009. The facility, housed in a former Maytag plant, produces towers for wind energy production. (UPI Photo/Brian Kersey)

U.S. President George W. Bush delivers his farewell speech to the Nation from the East Room of the White House in Washington, D.C.on January 15, 2009. (UPI Photo/Mannie Garcia/Pool)

Fireworks explode over the National Stadium, called the Bird's Nest, during the dress rehearsal for the 2008 Olympics in Beijing on August 2, 2008. The official opening ceremony for the Summer Games is August 8, 2008. (UPI Photo/Pat Benic)