A group of scientists has formally challenged the conclusions of a highly publicized report describing a mysterious microbe that seemed to thrive on a diet of arsenic.
The report, published in December by the journal Science, suggested that a bacterium found in California's Mono Lake was able to substitute arsenic for phosphorous, one of several elements considered essential for life.
Thousands rode their bikes Sunday for the 24th annual Rolling Thunder event from the Pentagon to the National Mall, a Memorial Day weekend tradition in Washington, D.C. There was a new rider this year: potential presidential candidate Sarah Palin, astride a Harley.
Many in the crowd were excited to see her, but some worried that her presence could distract from the day's message. But there was no doubt, Palin draws a crowd — even in a crowd.
She rode up on the back of a motorcycle in a black leather jacket, black flared pants, black heels and a wide smile.
On Sunday, President Barack Obama visits the tornado-ravaged city of Joplin, Mo. The death toll from last Sunday's tornado stands at 139, the deadliest tornado to hit the U.S. in more than 60 years. Host Liane Hansen talks with NPR's national political correspondent Mara Liasson.
Nature's fury has shown itself in killer tornadoes that have swept the Midwest and the South. Now comes hurricane season, which officially begins on Wednesday. Essayist Diane Roberts has seen both kinds of storm and knows which she'd rather deal with.