Coursera founders Andrew Ng and Daphne Koller are computer science professors at Stanford University. Jeff Chiu/AP hide caption
National
Sunday
Vice President Richard Nixon listens as Sen. John F. Kennedy talks during their televised presidential race debate. This photo was made from a television screen in New York, Oct. 21, 1960. AP hide caption
President Obama speaks during a campaign event at University of Colorado Boulder Sept. 2. He and his Republican challenger, Mitt Romney, will have their first debate at the University of Denver on Wednesday. Pablo Martinez Monsivais/AP hide caption
Saturday
President Barack Obama and Republican presidential candidate Mitt Romney both campaigned in the battleground state of Ohio this week. AP hide caption
Archbishop John J. Myers stands outside Cathedral Basilica of the Sacred Heart in Newark, N.J. The archbishop has urged followers to assess the presidential candidates for their views on abortion and gay marriage. Mel Evans/AP hide caption
New York Times publisher Arthur Ochs Sulzberger in his office in 1973. Anthony Camerano/AP hide caption
Thirty years ago this weekend, seven people died from ingesting Tylenol that had been poisoned. Since then, Johnson & Johnson has overhauled its packaging. iStockphoto.com hide caption
Mia Love, the mayor of Saratoga Springs, Utah, addresses the Republican National Convention in Tampa, Fla., on Aug. 28. She's running for Congress against incumbent Democrat Jim Matheson. J. Scott Applewhite/AP hide caption
County Sheriff Lee Baca faces what may be the toughest fight of his 14-year political career. Damian Dovarganes/AP hide caption
Friday
Polar bears in the Beaufort Sea in northern Alaska. Scientist Charles Monnett caused a stir with a 2006 report on polar bears that were drowning, apparently owing to a lack of ice. Steve Amstrup/Fish and Wildlife Service hide caption
Republican presidential candidate Mitt Romney speaks during a roundtable discussion on manufacturing this Wednesday in Bedford Heights, Ohio. MANDEL NGAN/AFP/Getty Images hide caption
A worker separates tomatoes at a market in Mexico City. The Commerce Department says it might act to end a 16-year-old trade deal governing fresh Mexican tomatoes sold in the U.S. Gregory Bull/AP hide caption
President Obama and Mitt Romney campaign in August: Obama in Leesburg, Va.; Romney in Waukesha, Wis. AP hide caption
Shepard Smith apologized to viewers Friday afternoon, after his show aired live footage of a man who fled police and then shot himself. Fox News hide caption
Linda McMahon (center) visits a senior center in Naugatuck, Conn., this month. Jessica Hill/AP hide caption