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Past Shows March 18, 2006  Listen to a Real Audio stream of the entire program (available Saturday, two hours after broadcast).
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Stardust Blows In Listen to or download the mp3 or Ogg files. (what's ogg?)
Stardust's collection system re-entering |
This week the first results from the Stardust space probe, which visited comet Wild 2 and flew through its tail, were presented at a scientific meeting in Houston. Stardust used a special collector to sample the dust in the comet's tail, and this week the researchers studying it revealed what they'd found, so far. Dr. Donald Brownlee, the principal investigator on the Stardust mission, and a professor of Astronomy at the University of Washington, said the minerals they found raised important questions about the evolution of the solar system. Despite being part of a comet that comes from the coldest part of the solar system, they showed signs of being exposed to temperatures only found in the near vicinity of the sun. Related Links
Giant Seed Spreading Insects Listen to or download the mp3 or Ogg files. (what's ogg?)
Adult male Auckland tree weta (Hemideina thoracica) - Courtesy, G. Gibbs |
Plants have a problem. If they want to spread their seeds, they can't just get up and move to a new location. So, they've come up with various strategies to move their progeny to far off locations. One of these strategies is to coat the seeds in a tasty covering. We call this fruit. When the fruit gets eaten, the seed passes through the digestive tract and is expelled far from the original plant. In most parts of the world birds and small mammals fulfil this function. But Dr. K.C. Burns, from Victoria University of Wellington, in New Zealand recently discovered that in his part of the world, it's a type of insect that's responsible for seed dispersal. The insect is a weta, a grasshopper-like creature that can weigh as much as a rat, and is thought to be one of the world's ugliest creatures. But the weta is being killed off by animals humans have introduced. This is putting plant and tree populations on the islands at risk. Related Links
A Whale Buffet Listen to or download the mp3 or Ogg files. (what's ogg?)
Sperm whale - Courtesy, Jan Straley |
A few years ago, the fishers of Southeastern Alaska noticed a problem. When they brought their long-line fishing gear back on board their boats, they were finding partial fish carcasses on some of the hooks. Something was eating part of their catch. At the same time, the fishers had noticed an increase in sperm whales hanging around their boats. They contacted Jan Straley from the University of Alaska, Southeastern in Sitka. She's figured out that the whales pick up on the sounds the boats make as the fishers draw up their lines. Then the whales come in, and pick fish off the lines. But they don't take all the fish, just those they find especially tasty. For the whales, the lines have become a floating buffet. Related Links
Brain Band-Aid Listen to or download the mp3 or Ogg files. (what's ogg?)
Dr. Ellis-Behnke at work - Courtesty, Donna Coveney/MIT |
Nerve cells in the brain or spinal cord rarely regenerate well. The body's immune system and wound-healing systems generally prevent neurons from growing back properly and repairing the damage done by injury or stroke. Dr. Rutlege Ellis-Behnke, a professor in the Department of Brain and Cognitive Sciences at the at the Massachusetts Institute of Technology thinks he may have found one way to overcome this difficulty. He and his colleagues have been experimenting with a special protein solution - a self-assembling nano-material. It begins as a liquid, but forms a fibrous gel when injected into the brain, and seems to help seal away a wound to nervous tissue from the body's own defensive systems. In hamsters, this treatment has allowed nerves that have been severed to regrow and restore lost function. Related Links
Antimony: The New Lead Listen to or download the mp3 or Ogg files. (what's ogg?)
Sample of Antimony |
Attempts to lower lead levels in the atmosphere have been very successful in the last few decades. But now, there's another metal out there, that has some scientists worried. It's antimony, a naturally occurring mineral, that's used in many different kinds of plastics. Dr. Bill Shotyk, from the University of Heidelberg, has been measuring antimony levels in the Arctic. He's found that, while lead levels have been dropping, antimony levels are on the rise. He's also finding antimony in water that has leached out of plastic bottles. Related Links
Question of the Week: Species Definitions Listen to or download the mp3 or Ogg files. (what's ogg?)
This week, Barry Milavsky in Toronto writes: We hear a lot about new animal species being discovered, and last week on your program, there was an old one rediscovered in Laos. We also hear about prehistoric human fossils being different species. Is there a quantitative way that scientists differentiate species? For instance, when looking at a Great Dane and a Chihuahua, how would you know that they are the same species?
For the answer we turn to Dr. Robert Reisz, Professor of Biology at the University of Toronto at Mississauga.
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