Despite a World Health Organization agreement, China has withheld samples of the bird flu virus H7N9 from U.S. scientists.
The waters of the Rio Grande are closely regulated. But what about the water hidden in aquifers deep below the Mexico-Texas border?
A sudden bridge collapse in Italy has sparked interest in the safety of structures worldwide.
Bear sightings at Yosemite National Park are down, but the park's infamous traffic poses a new threat.