VOA标准英语2010年-Our World — 20 March 2010（在线收听） |
VOA's weekly science and technology radio magazine Art Chimes | Washington DC 19 March 2010 Related Links This week on Our World: The amazing migration of the monarch butterfly ... how vitamin D might help to protect against heart attacks ... and the financial benefits of the Internet: BECKSTROM: "Look at the value Ebay creates. All that junk that was in your garage, your attic, that was worthless, you know, now collectively may be worth trillions of dollars." Celebrating the 25th anniversary of the first "dot-com," backyard chickens right here in Washington, and more. I'm Art Chimes. Welcome to VOA's science and technology magazine, "Our World."
Gene Study Tracks Dogs Origin to Middle East A new study of the genetic profile of dogs upends some previous findings about where the friendly canines first became a distinct species from wolves. It also sheds some light on the special relationship that humans and dogs have enjoyed for thousands of years. The study by researchers at the University of California, Los Angeles (UCLA), came to a different conclusion than previous research, which placed the emergence of dogs in East Asia. But there was no archaeological evidence to support that. And so now, UCLA evolutionary biology professor Robert Wayne and his colleagues say a more thorough genetic investigation points to the Middle East as the cradle of dog origins. WAYNE: "Our results, that are kind of a genome-wide analysis instead of focusing on just one gene segment, the mitochondria, suggest that the nuclear genome of dogs derived principally from Middle Eastern wolves with a little input from European wolves and even a lesser extent, input from East Asian wolves." And this time, says Wayne, the conclusion of a Middle East origin for dogs is buttressed by archaeological evidence. WAYNE: "There are dogs actually buried with humans [including] this classic burial site of a dog, a puppy actually, kind of nestled in the arms of a buried human. So their skeletons are side-by-side. But there's other archaeological remains, and even at that time period we have small, medium sized, and large dogs." Dogs show up in Middle Eastern archaeological sites as far back as 12- or 13,000 years ago, although evidence at other sites indicates dogs lived in Belgium 31,000 years ago and in Western Russia 15,000 years ago. In their genetic study of wolves and dogs, the researchers also explored whether there was anything in the DNA that might explain why dogs became domesticated as working animals or pets, and wolves did not. So they looked at places on the genome where the wolf and dog genes were most different. WAYNE: "And those spots in the genome are near genes which influence behavior. And one of our top hits is this very unusual mutation that, in humans, causes gregariousness. It's called the 'party gene' by some. And this is also one of our top hits in dogs, and for those of you that have had dogs, you know they tend to be very outgoing often, so this makes sense in terms of the behaviors that likely evolved in dog evolution." Dogs have been part of human communities for thousands of years. Perhaps originally they followed human hunter-gatherers and came for the food scraps and stayed for the companionship. Robert Wayne of the University of California, Los Angeles, writes about what genetics can tell us about "man's best friend," as we sometimes call our dogs, this week in the journal Nature. We'll have more on domesticated animals at the end of the show, but first ...
Vitamin D — sometimes known as the sunshine vitamin — has long been known to have a host of health benefits. But now, new research indicates it may help reduce the risk of heart attacks. Philip Graitcer has the details. GRAITCER: Vitamin D is one of the essential nutrients we all need. We get it through exposure to sunlight and through diet. Without enough Vitamin D, we are at risk for rickets, osteoporosis and bone fractures. Now, researchers have found that Vitamin D deficiency is also associated with increased risk for cardiovascular disease. J. Brent Muhlestein, a cardiologist at the Intermountain Medical Center in Salt Lake City, Utah, looked at vitamin D levels in a group of 41,000 patients who visited the medical center for various health problems. MUHLESTEIN: "We found a significant association with future heart attacks and strokes and death in the patients who were low compared to ones who were not low in that blood test." GRAITCER: About two-thirds of the patients had low levels of Vitamin D. One group took Vitamin D supplements to get up to normal levels. The other group did not. After a year, Muhlestein tested both groups again for Vitamin D. MUHLESTEIN: "What we found is that although they all started out low, the ones who had Vitamin D that was normalized at the follow-up Vitamin D tests were found to have significantly less cardiovascular events than the ones that were not normalized." GRAITCER: The numbers were striking. In the group of patients that took supplements to bring their Vitamin D up to normal levels, there was about a 30 percent decreased risk of cardiovascular disease. Muhlestein says these data show that not getting enough Vitamin D affects more than just bone strength. MUHLESTEIN: "Now we have data that says that it's also associated with significant cardiovascular risk and that it appears that if you treat it you can significantly reduce your cardiovascular risk as well." GRAITCER: Although Muhlestein says a large scale randomized clinical trial is needed to confirm his results, he thinks physicians should start recommending Vitamin D supplements to patients with low levels of the vitamin. He expects that would lower their risk of cardiovascular disease. Muhlestein's findings were presented on March 15 at the annual meeting of the American College of Cardiology in Atlanta. I'm Philip Graitcer.
Scientists Unravel Butterflies' Long-Distance Navigation Strategy Every year, Monarch butterflies winter in the mountains north of Mexico City, traveling up to 4,800 kilometers from places as distant as Canada. Now that it's spring in the Northern Hemisphere, the females are flying north, to lay their eggs as far north as the Central U.S. How such a tiny animal can fly such long distances with such precision has long been a mystery. But U.S. scientists are discovering surprising answers. From Mexico, Shelley Schlender reports: SCHLENDER: Deep in the forests of Michoacán, several hours drive north of Mexico City, tourists watch millions of Monarch butterflies as they cling to fir trees, gather on bushes, or take off in flight. TOURIST: It's like suddenly all the air is being touched by all the little butterflies. Millions of Monarchs stay here through winter then depart in the spring. Tagging programs led by U.S. scientists have shown that these butterflies migrate thousands of kilometers from the northern United States and Canada. In the spring, the females leave these fir tree forests and head as far north as Kansas, to lay their eggs on milkweed plants. It's an odyssey that inspires Chip Taylor, director of the international Monarch Watch program in Lawrence, Kansas, located about 2,000 kilometers north of the Monarch's winter habitat. TAYLOR: "We see them usually between the 14th and 21st of April if they get this far north, a lot of those butterflies are so tattered and broken, that they're crawling from milkweed and milkweed to lay the eggs. They can barely fly." SCHLENDER: Just as remarkable as the distance they fly is how the butterflies navigate. After all, they don't have guides, or maps, or GPS equipment. Instead, they use sight, smell, touch, and other senses to find their way. To study that, butterfly scientists track the insects' normal flight paths, then they confuse them and track the path again. Taylor says his research teams used this method to discover that butterflies need accurate information about the earth's magnetic fields. TAYLOR: "Ten seconds of exposure to the strong magnetic field was enough to totally disorient the butterflies. They could not maintain a course." SCHLENDER: Sunlight matters, too, and by manipulating artificial sunlight, scientists can fool the butterflies into traveling in the wrong direction. At the University of Massachusetts, neuroscientist Steven Reppert uses a sophisticated apparatus to study the Monarch Butterfly's migration. His research team connects a butterfly to a thin wire tether to track its normal flight path and then to track how that path changes once they've confused it. Based on flight simulation studies, Reppert says that Monarchs use visual cues about the daylight sky to set their internal compass, and their brain's circadian clock, which regulates hormones and behavior. Reppert says researchers thought they had this control system mostly figured out. But then they took a closer look at the insects' antenna. REPPERT: "The antenna are really remarkable organs. They're odor sensors. But they do a lot more than that. They can sense vibrations, they can act as ears, they can sense changes in barometric pressure, so there's a number of things that the antennae can do." SCHLENDER: To study these abilities, Reppert's team decided to confuse the butterflies, at least a little, by removing their antenna. But this did more than eliminate their sense of smell and vibration. It totally befuddled their navigation. REPPERT: "This finding was actually quite heretical to us. We did not know quite what to do with it at the time." SCHLENDER: They devised another experiment. On the chance that smell mattered more than they had realized, the researchers painted butterflies' antenna to block their odor receptors. And just in case sunlight played a role, Reppert's team used clear paint on some butterflies' antenna and black paint on others. The clear paint allowed in daylight, and those butterflies navigated normally. REPPERT: "The ones painted black had disrupted orientation." SCHLENDER: This meant that the Monarch's antenna can detect light. But an even bigger surprise was up ahead. Scientists knew that the circadian clock in the insect's brain responds to light signals from the eyes. They had assumed that that system provided all the daylight data that the butterfly's navigation system needed. But it turns out that the circadian clock signals produced in the butterfly's antenna are at least as crucial as the clock in its brain. The butterfly's bug-sized GPS needs that antenna data, so that when winds and other surprises hit, the Monarch still flies in the right direction. As for how all these pieces work together, Reppert says, the clues are tantalizing. REPPERT: "The antenna are talking to the brain and controlling the behavior in a very specific way. And we need to understand that." SCHLENDER: Reppert's lab plans more experiments. He predicts they'll find that the ability of the Monarch's antenna to sense odors and magnetic waves may also help them set the course for the day. And he says the lessons learned will help us understand the role of circadian clocks in other animals, including people. For VOA News, I'm Shelley Schlender in Michoacán, Mexico.
Time again for our Website of the Week, when we showcase interesting and innovative online destinations. This week it's a place for up-to-date science news presented with a bit of a quirky edge. ZEEBERG: ""DiscoverMagazine.com is the web version of the print Discover Magazine, and it is a science news site that includes all kinds of information, all kinds of news about science, technology and the future." Amos Zeeberg is web editor at DiscoverMagazine.com, which takes its name and some of its content from its print cousin, but it goes beyond what you'll find in the pages of the magazine that's delivered to 600,000 subscribers each month. Recent stories on the website feature micro-size aircraft, fake science served up by Hollywood, and real research underway in Antarctica. And the site is host to eight blogs (at last count), featuring individualized takes on the latest science news. ZEEBERG: "So now it takes a lot of advantage of the strengths of the Internet. So we have a lot of news that goes on here. We're putting up probably around 15 or 20 blog posts a day because people are online all the time, and they want to know about what's happening new in science." Amos Zeeberg hinted that in the coming months they'll be introducing a web-based TV show, but that was about all he could say about it for now. So keep your eyes open for that and other great science-related content at DiscoverMagazine.com, or get the link from our site, VOAnews.com. MUSIC: Adam Routh — "Moon Hop" You're listening to Our World, the weekly science and technology magazine from VOA News. I'm Art Chimes in Washington. US Officials Outline High Speed Internet Upgrade The Obama administration this week announced a long-expected plan to expand high-speed Internet connections to every household and every business in the country. The national broadband plan also calls for greatly increasing connection speeds, which have lagged behind many other advanced nations. The former head of the Federal Communications Commission, Reed Hundt, says there'd be many benefits from faster Internet connections, including innovations in health care, smarter ways of using energy at lower cost, expanded educational opportunities, and more. HUNDT: "So these public goods of health, energy, eduation, democracy, and safety are all going to be distributed to everyone in America and substantially improve the standard of living and the way that we interact with each other." The plan would take a decade to implement and faces technological, financial, and political challenges. Internet Scams, Fraud Boost Online Crime Complaints The prospect of greatly expanded use of the Internet also raises concerns about a similar growth in online crime. A new report says complaints about cyber-crime were up 22 percent last year compared with 2008. Internet users, mostly in the U.S., complained about scams, frauds, and identity theft. The cost to consumers was more than half a billion dollars. The data were collected by the Internet Crime Complaint Center, a joint effort of law enforcement and private organizations. E-mail scams were the biggest single category of complaints, followed by online sales in which either the buyer didn't pay or seller didn't ship the product.
That sort of mischief is, sadly, a fact of life, but probably not something that Internet pioneers thought much about 25 years ago this week, when the first dot-com web address was registered. At an event marking the occasion in Washington, former president Bill Clinton cited the powerful impact the Internet has had on the U.S. economy alone. CLINTON: "Today, about three million people make a living directly and indirectly because of the Internet. And it's directly about two percent of our GDP. Indirectly I think it has done much more." Since leaving the White House in 2001, Mr. Clinton has focused on international health and other issues through his foundation. And in that work, too, he says the Internet has made a powerful difference, such as facilitating emergency fundraising efforts after January's earthquake in Haiti. CLINTON: "We raised approximately $22 million of the money we raised — we raised almost twice that — but we got that from 200,000 Internet donors. I don't know what I would do without [the Internet]. The first dot-com website was registered on March 15, 1985, to a now-defunct computer company called Symbolics. Industry analyst Robert Atkinson said the birth of the dot-com domain set the stage for the explosive growth of the Internet over the past quarter-century. ATKINSON: "NSF, the National Science Foundation, had recently opened up the Internet, which was essentially a research network, and they decided to open it up and try an experiment and let companies join the network, with the thinking that there were companies who were engaged in research. Little did they know that by doing that, they were creating probably one of the biggest technology revolutions in world history." Atkinson heads a group called the Information Technology and Innovation Foundation, which has been studying the economic impact of the estimated 80 million dot-com websites. Commercial use of the Internet has also helped ordinary people to get into business. Internet veteran Rod Beckstrom says selling unwanted houshold goods on Ebay is just one example. BECKSTROM: "Look at the value Ebay creates. All that junk that was in your garage, your attic, that was worthless, you know, now collectively may be worth trillions of dollars." Well, maybe not the stuff in my garage. And by the way, the owner of that first dot-com website, Symbolics Computer, may no longer be with us, but the Symbolics.com website lives on. It was bought by a firm called XF.com Investments. Their portfolio includes both commercial real estate and virtual real estate, in the form of domain names. Urban Chicken Farmers Face Challenges in Quest for Fresh Eggs And finally today ... Washington, D.C. is well known as a home to American presidents, congressional lawmakers, and power brokers. Now, if some capital-city residents have their way — it'll also be home to urban chicken farmers. These poultry pioneers are part of a growing movement of Americans who are promoting local production as an alternative to the country's industrialized food system. But as VOA's Steve Baragona discovered, not everyone in Washington thinks chickens will make good neighbors. BARAGONA: In a modest yellow townhouse, just a few kilometers from the U.S. Capitol, live three of Washington, D.C.'s most unusual residents. While backyard poultry are a common sight in the developing world, they're hardly ever seen in America, where most chickens are raised on large commercial farms. These chickens belong to D.C. resident Amanda Cundiff. She grew up outside Los Angeles, California, but she says she has a special history with chickens: CUNDIFF: "I grew up in a city with a backyard with a chicken in it named Henrietta. So it didn't ever seem like a funny thing to me to have chickens in the city." BARAGONA: Cundiff's three birds eat table scraps. Their manure makes ideal compost for her garden. And she says her chickens lay the freshest eggs imaginable — great for scrambling, straight from the backyard. Cundiff and her backyard eggs reflect a growing trend in America. Concerns over food safety and the environmental and health impacts of industrial agriculture are on the rise. So, many people like Cundiff are seeking out locally grown or organic food, or growing it themselves. CUNDIFF: "I don't see any reason why we shouldn't be growing our own food, even when we live in cities. I think it's really important to be connected to where our food comes from and not just think it comes from a supermarket." BARAGONA: Cundiff is not the only Washington resident who wants to raise her own chickens. But city laws say chicken coops must be at least 15 meters away from any human residence. Cundiff's backyard is big enough, but most are not. One of her neighbors who was also raising poultry in her backyard didn't know she was violating city laws until an unknown passerby saw the chickens. CUNDIFF: "The person who was walking by reported my neighbor to the police, who came, and animal control came and took their chickens." BARAGONA: So Cundiff and her neighbor took the issue to City Hall. They won the support of D.C. City Councilman Tommy Wells. But Wells says it took some persuading. WELLS: "I thought it was nuts. But other cities are doing it." BARAGONA: Several towns and cities across the United States have recently made it easier for residents to keep backyard chickens. Even New York City has less restrictive laws than Washington, D.C. But some in Washington don't think chickens belong in the city. Ted Knutson is a reporter living in the Capitol Hill neighborhood. KNUTSON: "People live in the rural areas to get away from the noise of heavy traffic. Vice versa, people live in the city to get away from rural things." BARAGONA: Knutson says he's concerned that the chicken waste might spread disease and attract rodents. But Councilman Wells says under his proposal, neighbors don't need to worry. WELLS: "There hasn't been shown to be much of a health risk at all. In fact, the regulations are so tightly written that you have to be inspected once a year by the health department." BARAGONA: And if a neighbor wants to raise chickens, Wells's bill would allow any resident within 30 meters to veto them. The proposal is stuck between the health department and the city council, and these days, the council has other priorities. So, for the time being, Amanda Cundiff is one of the few in this city eating eggs laid in the shadow of the nation's Capitol. Steve Baragona, VOA News, Washington MUSIC: "Our World" theme That's our show for this week. Please stay in touch. You can email us at [email protected]. Or write us at — Our World Our program is edited by Rob Sivak. Bob Doughty is the technical director. And this is Art Chimes, inviting you to join us online at voanews.com/ourworld or on your radio next Saturday and Sunday as we check out the latest in science and technology in Our World. |
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