VOA标准英语2010-Our World - 3 April 2010（在线收听） |
VOA's weekly science and technology radio magazine Art Chimes | Washington, DC 02 April 2010 Related Links CLAYTON: "When a bird hears another bird singing or sings himself, this seems to engage a very large number of genes in the brain: genes are being turned off, genes are being turned on." What birds learning to sing can tell us about babies learning to speak, and more... I'm Art Chimes. Welcome to VOA's science and technology magazine, "Our World." Study of Tree Rings Indicates Climate Change Played Role in Demise of Angkor For hundreds of years, the Khmer empire ruled in what is now Cambodia. But in the 13th century, the capital city, Angkor, fell mysteriously into ruin. Now, a new scientific study indicates that it was climate, specifically decades of drought interspersed with intense monsoons, that helped bring down the Khmer capital. Brendan Buckley, the Columbia University scientist who led the study, says that in the ancient world, Angkor was known for its sophisticated water system. BUCKLEY: "Well, Angkor was really the dominant civilization in that part of the world without any question. It was the center of their universe. And it was called the 'hydraulic city' because it had really, remarkably massive arrays of barays, which are these giant water tanks and a series of canals and interconnected waterways that was really unparalleled in the ancient world in that part of the world." Buckley isn't an archaeologist. He studies tree rings, which record the growth history of trees that can be hundreds of years old, or even older. A new ring is added every year, and thicker rings represent a kind of savings account, when the tree collects more nutrients than it can use. Thin rings show the tree is barely getting along, like during a drought year. Using samples from around Southeast Asia, Buckley and his colleagues saw this pattern in tree rings from recent years, when he could corroborate the rings with other historical climate information. His newest tree ring samples, from [a rare cypress, Fokienia hodginsii, in] southern Vietnam, enabled him to take the climate record back much further. BUCKLEY: "We realized we have trees that are more than 1,000 years old. And we started seeing these big, giant periods of drought that took place around that time. And as I started to get more interested in the history of Southeast Asia I realized that that was the time of the collapse of Angkor." The research team used what are called core samples from hundreds of trees throughout Southeast Asia. They use a hollow tube to drill into the tree and extract a 5-mm wide cylinder that shows each ring starting with the most recent, just under the bark. By comparing rings from different trees and with other historical data, you can often identify particular rings with the exact calendar year that they grew. BUCKLEY: "We were able to match up the narrow and wide rings exactly so that we can assign the exact calendar dates to the exact rings of every tree. In the tropics, a lot of tree species don't even form rings that we can see. So to be able to get a tree that, first of all, has very clear rings that we're able to visually match to each other and then go through and produce these long records was remarkable." The rings tell a story of decades of drought, which dried up Angkor's extensive water works, followed by monsoons that overwhelmed the 'hydraulic city.' The climate shifts weren't the only factor at work in the decline of the Khmer capital, which was a long time coming. Buckley quotes his co-author, Daniel Penny, as saying the climate was the "final nail in a coffin that took about 200 years to build," as Angkor and the Khmer empire were being buffeted by political, social, and economic stress. BUCKLEY: "The times were changing, [shifting] toward an economic system that was taking them more to the coastline so they could trade with China more readily. I believe that drought was one of the things that piled on to the pile of things that were affecting the Angkorians at that time. And it may very well have provided that final impetus to really kind of kill off this inland agricultural system." The idea of a civilization being pushed over the edge by climate change resonates today, of course, so I asked Brendan Buckley what lessons his research on 13th century Southeast Asia has for today. BUCKLEY: "We probably have more abilities to adapt than they did at the time. But one of our biggest problems is a very large agrarian based population in places like India or Southeast Asia. And it's very hard to adapt to that giant population being in an area that is likely to be hit by these kinds of problems. The other thing is that rising sea level, which we're already seeing the evidence of in places like Ho Chi Minh City is a great example. So this is becoming an actual problem that we can see in real time on the ground. I guess that remains to be seen how we're going to cope with it." Prof. Brendan Buckley's paper on climate's contribution to the demise of Angkor in present-day Cambodia was published online this week the Proceedings of the National Academy of Sciences. Here in the United States, Asian, African-American, Hispanic, and Native American children have higher rates of death and more illness compared to white children. That's the finding of a new analysis of more than 750 published studies on children's health. Philip Graitcer has our report. GRAITCER: The findings were based on data from 50 years of studies on children's health and health care disparities. FLORES: "Racial and ethnic disparities in children's health and health are quite extensive, pervasive and persistent." GRAITCER: Dr. Glenn Flores, a pediatrician at the University of Texas Southwestern Medical Center, was the report's author. He says these differences between minority kids and Caucasians were found in every area of health and health care. FLORES: "Disparities were noted across the spectrum of health and health care including mortality, access to care and use of services, prevention, population health, health status, adolescent health, chronic diseases, special health care needs, quality of care, and organ transplantation." GRAITCER: Minority children have a higher incidence of HIV/AIDS, sexually transmitted diseases, asthma, certain cancers, and even success rates for treatment of kidney and heart diseases. And these differences led to disproportionate death rates. FLORES: "Mortality disparities were noted for all four major U.S. racial and ethnic minorities groups." GRAITCER: What was particularly disconcerting to Flores was that even when studies were adjusted for such things as income, the differences remained. And according to Flores, the explanation for these differences is not apparent because clear and consistent data are not available. FLORES: "Optimal health and health care for all children will require recognition of disparities as pervasive problems, methodologically sound disparity studies, and rigorous evaluation of disparities intervention." GRAITCER: The study appears in the April issue of the journal Pediatrics. That's today's health brief, I'm Philip Graitcer. An international team of researchers has sequenced the genome of a bird called the zebra finch. Their work reveals a lot about songbird genetics, and opens a new door to understanding the basis of human speech. Véronique LaCapra reports. LaCAPRA: That's the song of the Australian zebra finch. It's named for the black and white stripes on the male's throat — he's the one who does all the singing. The zebra finch survives well in captivity. That makes it both a popular pet and a favorite subject for researchers. University of California-San Francisco psychiatrist and neuroscientist Allison Doupe got interested in finches because they provide a model for understanding how people learn to speak. DOUPE: "Birds and humans both have to hear adults early in life, during a critical period and then they have to practice — their first vocalizations are like babbling in babies, and they have to hear themselves while they practice, and then they gradually get better and better, and […] so it turns out that lots of the behavior is fairly similar between speech learning and songbird learning." LaCAPRA: Songbirds are one of the few groups of animals that — like humans — are capable of vocal learning. Others include whales, elephants, and bats. Researchers have been studying the zebra finch to try to identify the genes that make this vocal learning possible. CLAYTON: "When a bird hears another bird singing or sings himself, this seems to engage a very large number of genes in the brain: genes are being turned off, genes are being turned on." LaCAPRA: That's neurobiologist David Clayton, from the University of Illinois at Urbana-Champaign. He's one of the lead researchers in an international team that has sequenced and analyzed the genome of the zebra finch. A previous study by Clayton's lab had shown that as a young finch first learns how to sing, hundreds of genes in its brain quickly respond, producing more or less protein. Now, with a map of the whole genome in hand, the researchers looked at how individual genes in the adult finch brain respond to singing. CLAYTON: "We found a surprisingly large number of genes are being regulated." LaCAPRA: In fact, they found that at least 800 genes spring into action in a finch's brain whenever it sings. Not only that, but most of those genes are of a kind that scientists used to think of as molecular junk: instead of producing proteins, the genes produce something called non-coding RNA. CLAYTON: "That non-coding RNA: well what does it do? Well it's not that it's going to make a protein. It's going to turn around and bind to other RNAs, physically bind to them, in a way that will then determine whether those other RNAs get made into protein or not." LaCAPRA: Wes Warren is the assistant director of the Genome Center at Washington University in St. Louis, and a leader of the finch genome sequencing project. He says that the same kinds of complex genetic interactions that are happening in the songbird brain are probably happening in ours. WARREN: "As you're hearing my words as I'm speaking, your brain is processing those words, and we think analogous to what's going on in the bird, there's genes in particular areas of your brain, that are being expressed very rapidly or decreased very rapidly to allow you to process that information." LaCAPRA: Since we've heard those words before, Warren says our brain has formed a kind of "molecular memory" of them. WARREN: "And your ability to decipher them and understand them and reproduce them is a response to all these genes that are being regulated in your brain." LaCAPRA: Warren says now that researchers have a map of the zebra finch genome, they can carry out experiments to identify which genes in the finch's brain are most critical to hearing and producing song — and by extension, which genes may play a role in human speech disorders, like those related to stuttering, autism, and Parkinson's disease. Researchers will also be able to learn more about songbird evolution. DOUPE: "The songbird community as a whole I think is very excited about this." LaCAPRA: Allison Doupe wasn't involved in the finch genome research — but she's been looking forward to its completion. DOUPE: "It's really the beginning of the next age of studies of songbirds, where we're going to have lots of additional tools." LaCAPRA: The zebra finch genome analysis is published in the current issue of the journal Nature. For VOA News, I'm Veronique LaCapra in St. Louis. Time again for our Website of the Week, when we showcase interesting and innovative online destinations. This time, it's a place to learn about climate change, with help from scientists who use satellite data to study what's happening down here on earth: NASA's Global Climate Change website. JENKINS: "Our goal is to tell the story of climate change in a simple but compelling way. And we do this through the eyes of the NASA scientists, through the eyes of the satellites that we have orbiting the planet and through a whole bunch of visuals, interactives, and other stuff." Amber Jenkins is a physicist and science writer at NASA's Jet Propulsion Laboratory, home of climate.nasa.gov. Isn't NASA about astronauts and exploring Mars, you might wonder. Well, a big part of what NASA does is based on its science satellites. And Jenkins says the space agency's satellites, bristling with cameras and sensors, allow us to get the big picture, to look at Earth in ways that are impossible here on the ground. JENKINS: "We can step back and look at our planet in completely new ways that you can't necessarily do when you're on the ground. And the measurements that we can make with our satellites as they orbit our planet give us information and a much bigger picture than in some cases we'd never been able to get until we'd ventured out into space." NASA's climate home page is a bit overwhelming, with lots to explore, but don't miss one called "Eyes on the Earth 3D," an exciting feature based on video game technology. JENKINS: "You can explore all the different satellites that NASA has right now collecting data about climate and climate change. And the data piped through into that from space is in some cases very, very new, just a few hours old, so you're really getting a very, very up-to-date snapshot of the planet." And there are special features for kids and for educators at NASA's Global Climate Change website, climate.nasa.gov, or get the link from our site, VOAnews.com. MUSIC: Ali Friend — "Clumpy Jack" It's Our World, the weekly science and technology magazine from VOA News. I'm Art Chimes in Washington. Inventors Hall of Fame Honors Innovators This week, the U.S. Inventors Hall of Fame inducted its latest members. The new honorees have to their credit video games, rockets, kitchenware, and artificial diamonds, among other inventions used in home, office, industry and space. A real rocket scientist, Yvonne Brill, was cited for developing the hydrazine thruster that keeps satellites in the correct orbit. Her invention came about the way inventions are supposed to happen. She had a problem to solve, worked hard, and came up with the solution. Donald Stookey was honored for inventing glass ceramics, used in missile nose cones and in CorningWare kitchen products. His invention was the result of an accident — putting glass in an oven that was too hot. He expected a mess, but what he got was a new kind of material with useful properties. He told me that for him, the unexpected is expected in the discovery process. STOOKEY: I've been surprised many times. A lot of those things that came from my research, I had no advance knowledge of what would be coming out." Another Hall of Famer, Spencer Silver, invented a semi-sticky adhesive. No one in his company, 3M, could figure out a use for it. Six years later, another 3M employee, Art Fry, realized it could be used to make bookmarks that wouldn't fall out of the book, but that could be peeled off without damaging the paper. The Post-It Note was introduced 30 years ago this month. Silver says corporate labs are cluttered with great inventions waiting for their moment of fame. SILVER: "I think every company has gold nuggets lying all over the floor. They just have to find somebody that can reach down and pick 'em up." Also honored this week is Ralph Baer, creator of the first home video game console. He developed it while working for a military contractor, which licensed it to Magnavox, which released the Odyssey system in 1972. He said many of the features he pioneered are still in use three decades later. BAER: "But still, you look at today's games, [ and they have] a lot of my DNA in them -- In the very beginning we had things like joysticks, light guns, color, sound, voice over. You name it." Baer is 88 years old and he's still developing new inventions. Other inventors inducted in this week's ceremony include Roger Easton for work that led to GPS navigation, cancer researcher Judah Folkman, and the team that made the first synthetic diamonds. The National Inventors Hall of Fame now includes more than 400 members. Frank Cepollina, who was inducted in 2003, says it's important to honor the men and women who have made useful and practical contributions to society. CEPOLLINA: "I think it really represents the human spirit of people in terms of being able to come up with ingenious ideas, then getting down to do the real work of converting those ideas into reality." Cepollina also says having an Inventors Hall of Fame and publicly honoring inventors helps inspire young people to pursue careers in science and technology. Protected California Ocean Area Helps Scientists Track Water Pollution The Inventors Hall of Fame also admitted Jacques-Yves Cousteau and Emile Gagnan, who developed the self-contained underwater breathing apparatus — better known as SCUBA equipment — which has allowed divers to appreciate the beautiful world below the surface in places like California's Point Lobos Underwater Reserve. While off-limits to fishermen, recreational divers enjoy the park's pristine conditions while scientists use them to measure change over time to the environment. Rachel Abrams reports from Point Lobos, California. ABRAMS: Brandon Smith knows the importance of double-checking his SCUBA gear before he gets underwater. SMITH: "You have to do everything a specific way every single time, and you don't want to make mistakes, because the worst time to find out that something's not working is, like, when you're sixty feet under water." ABRAMS: So Smith and his two companions check their air tanks, valves and depth gauges as they get ready to dive to 18 meters at the Point Lobos Underwater Reserve. He says the expansive waters of Point Lobos have appealed to him for years. SMITH: "It's just beautiful, but just specifically in Point Lobos, it just seems like everything's a little bigger. I never knew that starfish could ever get as big as they get. I mean to see one that's like two feet in diameter and it's just cruising along the bottom, it's just kind of like, 'Whoa! Oh my god!' But it's a lot of fun. It's neat to see. It's definitely eye-opening." ABRAMS: The same conditions that make Point Lobos popular among divers appeal to scientists as well. Point Lobos' protected conditions provide a base line to which researchers can compare data to measure environmental change. GARZA: "And without that base line, it's hard for us to try to ascertain if any of the differences or changes that we see long-term can be attributed to things like environmental change or human-mediated impact." ABRAMS: Dr. Corey Garza is an assistant professor in the division of Science and Environmental Policy at California State University, Monterey Bay. He notes that the biggest threat to these protected underwater areas is people — poachers, boaters who spill oil, even visitors who disrupt the ecosystems by taking home souvenirs. Native Americans, Chinese fishermen, and Japanese abalone harvesters have all called this area home at one point or another, so Garza says the story of the park is also one of the human experience. GARZA: "We've changed our use of the environment over time and that's kind of one of the great historic things that marine reserves can do for us, is just give us an estimate of how we've sort of changed some of these ecosystems, both through our use of it and in terms of what we're taking out of it." ABRAMS: Park rangers like Chuck Bancroft help maintain these protected marine areas by enforcing the park's rules, doing a little bit of everything related to the upkeep of the Reserve, and teaching the public about life underwater. Bancroft has worked at Point Lobos for close to thirty years. BANCROFT: "To me, the thrill is being able to see things here and then pass it on to another generation." ABRAMS: Bancroft says he loves talking to students about the marine life here and the history of Point Lobos. The school groups he sees come from all around California, and other visitors come from even farther away. BANCROFT: "We actually have handouts in twenty different languages to welcome people from around the world that come to visit here. California State University's Corey Garza says visitors like these, and divers like Brandon Smith, help make scientific research in the area is possible. GARZA: "You can't have research and you can't have conservation unless you have a public that's actually invested in conserving that. And so those parks actually provide for this educational aspect, as well helping people understand what the marine environment is, what's in there, and why is what you find in there important to them? So that's what I think the real big value of parks are." ABRAMS: Not only has this research added to our understanding of the ocean, it's helped shape government policies. Studies conducted by different institutes around Point Lobos provided the scientific basis for laws which created protected marine areas, including Point Lobos itself, which became a reserve in 1960. As a diver, Brandon Smith understands the importance of protecting these areas, both for the creatures who live here and the people who enjoy it. SMITH: "If you're going to learn about the ocean, there's no better way of learning it than seeing it first-hand." ABRAMS: Conservationists hope that scientists, and respectful visitors, will keep that possible at Point Lobos for years to come. Rachel Abrams, for VOA News, Point Lobos, California. That's our show for this week. Please stay in touch. You can email us at [email protected]. Or write us at — Our World
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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