Pfizer, one of the largest drug makers in the U.S., saw $27.8 billion in sales in 2009. Seven drug companies, including Pfizer, have disclosed information about doctors who receive payment for speaking fees related to products they sell. Mark Lennihan/AP hide caption

Scientists exposed the brains of specially engineered lab mice to pulses of light and saw brain cells responding as if they were triggered by an odor. The research could be applied to diseases including Alzheimer's and Parkinson's. Eric Isselee/iStockphoto.com hide caption

Candidates in the New York governor's race — Carl Paladino (from left), Jimmy McMillan, Andrew Cuomo, Charles Barron, Howie Hawkins, Kristin M. Davis and Warren Redlich — participate in Monday's debate at Hofstra University in Hempstead, N.Y. Audrey Tiernan, Pool/AP hide caption

Pedestrians walk past graffiti-covered street art in Kosovo, which continues to suffer from poverty, corruption and unemployment. Sylvia Poggioli/NPR hide caption

Chevy hopes it can gain some momentum in the small-car market with the Chevrolet Cruze. But it will face competition from Ford, Honda and Toyota. Steve Fecht/General Motors via Getty Images hide caption

President Obama and Gen. Stanley McChrystal in the Oval Office on May 19, 2009. McChrystal's firing this summer following his comments in a magazine interview prompted soul-searching within the military. Pete Souza/The White House/Getty Images hide caption

Facebook CEO Mark Zuckerberg at Facebook headquarters in Palo Alto, Calif., on Oct. 5. Facebook said it was working to fix the privacy problem reported by The Wall Street Journal. Paul Sakuma/AP hide caption

Bates and his research team used pingpong balls and red pipe cleaners to model the "hairy spherical block copolymer particles." The actual spheres are roughly 1 million times smaller, and each contains about 200 polymer molecules, represented by the red pipe cleaners. Courtesy of Frank Bates hide caption

Former Rep. Tom Tancredo, the Constitution Party candidate (left), Republican candidate Dan Maes (center), and Denver Mayor John Hickenlooper, a Democrat, at a television debate last month. Tancredo's presence in the race has split the Republican vote. Ed Andrieski/AP hide caption

Quarteto Olinda is a popular forro collective from the Brazilian city that bears its name. Courtesy of the artist hide caption