VOA标准英语2009年-Our World – 5 December 2009（在线收听）

VOA's weekly science and technology radio magazine

Art Chimes | Washington, DC 04 December 2009

MUSIC: "Our World" theme
               
This week on Our World: Climate change and its impact on health, ahead of the Copenhagen climate conference ... another hazard in cell phone use ... and the challenge of getting the human body to regrow arms and legs ...

WEIGHTMAN:  "Right now, I think we're limited to about a centimeter. And you've probably seen the pictures of growing the end of a finger tip back; we can do that now, but much past a centimeter, things just stop."

Those stories, the challenge of illegal commercial fishing, and more.

I'm Art Chimes. Welcome to VOA's science and technology magazine, "Our World."

On Monday, the United Nations opens its climate change conference in Copenhagen, the latest step in the quest for a solution to global warming.

The meeting is attracting scientists, activists, and many political leaders, including President Obama.

A U.S. target of reduced greenhouse gas emissions announced last month gives some hope to those who are looking for a consensus, but Eileen Claussen of the Pew Center on Global Climate Change says what is needed is a treaty on emissions, not just the right words.

CLAUSSEN:  "The political commitments leaders are bringing to Copenhagen offers a promise, but they will only be political commitments, and in the end the ultimate test of Copenhagen's success is whether it puts countries on a clear path to conclude a legally binding agreement in 2010."

Meanwhile, a new report in the British medical journal The Lancet highlights an aspect of climate change that hasn't gotten much attention – the public health benefits of working to prevent global warming.

As VOA's Rosanne Skirble reports, driving less, walking more, reducing our household energy use, and modifying our diets can lessen the impact of global warming ... and improve our lives, as well.

SKIRBLE:  The Lancet Health and Climate Change series highlights the health benefits that derive from cutting carbon emissions in four areas: household energy use, transportation, electricity generation, and agriculture.

Research was conducted by an international team of scientists led by Andrew Haines, director of the London School of Hygiene and Tropical Medicine.
   
In the household energy study, for example, the authors predict dramatic health benefits with the introduction of 150 million clean burning cook stoves in India.

Haines says the initiative cuts emissions, lowers health costs and saves lives.

HAINES:  "By 2020, we would avoid roughly 30 percent of the deaths from acute respiratory infections and from chronic airways disease. So overall there might be perhaps two million or so avoided deaths over that decade by introducing that cook stove program."

SKIRBLE:  In the transport study, authors focused on London and Delhi, India. Both showed substantial health gains from increased walking and cycling and reduced driving. The researchers found the strategy lowered the rate of heart attacks and strokes by 10-20 percent and depression by five percent.

The third paper in the series looks at case studies of renewable electric power generation in the European Union, China, and India, where Haines says a move to wind power or other alternative sources of energy would avert significant numbers of premature deaths.

HAINES:  "By 2030 we might have perhaps over 90,000 in India, just under 60,000 in China and somewhat under 10,000 in the EU. And the reason for that is of course the levels of air pollution in India and China are higher than those in the EU. So, if you reduce the levels of air pollution further, by moving towards these new technologies then obviously you are going to reduce the deaths further."

SKIRBLE:  While the initial costs of these energy initiatives might be high, the authors conclude that their cost would be partially offset by the health gains and fuel savings.

The Lancet series also addresses emission reduction strategies in the field of agriculture, which produces between 10 and 12 percent of global warming emissions.

A study of the livestock industry in Brazil and England concludes that a 30 percent reduction in meat animal production matched with a 30 percent reduction in consumption of animal products would not only slow climate change but also prevent diet-related deaths.

Lancet editor Richard Horton says the Lancet series seeks to strengthen the case for bold steps to reduce emissions by policy makers and negotiators in Copenhagen. Until now, he says, action on climate change has been stalled because of the perception that such efforts would mean unacceptable economic loss.

HORTON:  "The whole way we framed this climate change discussion politically has been wrong. And what we are saying is, reframe it about the the family and the benefits that can be delivered to the individual. And then you can begin to see an incredible political motivation for acting."

SKIRBLE:  This new perspective, Horton adds, can help build public support for the otherwise unpalatable and politically difficult choices necessary to mitigate global climate change.

Rosanne Skirble, VOA News, Washington

And one more climate change story: the result of a 10-year study that has implications for biodiversity in a changing climate.

The study suggests that an increase in greenhouse gases may not be as bad for biodiversity as some experts have previously suggested.

Biodiversity is important because different plant and animal species interact in ways that are complex, and sometimes the loss of one species can have impacts that are hard to predict.

Previous experiments found that excess nitrogen - from vehicle exhausts and fertilizer, for example – resulted in a 25 percent loss of biodiversity in Central Europe.

University of Minnesota forestry professor Peter Reich says the theory behind this is actually pretty simple. Nitrogen is a key nutrient that enables plants to grow.

REICH:  "Under rising CO2 or nitrogen pollution, species that are better adapted to these high resouce levels are likely to become more abundant and more dominant and thus crowd out other species."

Nitrogen pollution in Reich's study reduced biodiversity by 16 percent. Some scientists had predicted that adding higher levels of carbon dioxide to the mix would result in an even bigger loss of biodiversity. CO2 is, after all, like nitrogen, a plant nutrient.

Instead, the open-air study found that increasing the amount of CO2 in the air, adding to levels of nitrogen pollution typical of cities in Europe or China, didn't increase the loss of biodiversity, it actually cut the loss in half.

The experiment was done in Minnesota, and an earlier study in California had somewhat different results. The two used different plants in different climates. And Reich says that illustrates the difficulty in tracking cause and effect in complex ecosystems.

REICH:  "I might argue that a study of annual grasslands in California and perennial grassland in  Minnesota probably isn't a sufficient set of experiments to extrapolate about boreal forests across Siberia or the tropical forests in the Amazon in that we actually need a few more studies to know when and whether these interactions are likely to occur."

But interviewed in a Science magazine podcast, Reich said the results of his experiment don't give carbon dioxide a pass in the climate change debate.

REICH:  "Although this is good news for biodiversity, these findings don't in any way lessen the need for strong policy action to curb CO2 emissions, given all the other ways CO2 is impacting the planet."

Peter Reich of the University of Minnesota. His study was published this week in the journal Science.

Back in September we reported on the growing controversy over a possible association between mobile phone use and cancer, especially brain cancer.

Some evidence suggests there may be a link, but other studies failed to show a connection. Cell phones have been in widespread use for only a few years, and if they do cause cancer, the disease may not show up for years. So, many experts say it's probably best to use an earpiece or other hands-free function, rather than holding the phone right up to your head.

But mobile phone use presents another hazard that's a lot less controversial. Using a phone while doing something else can be distracting, which is why a growing number of governments have moved to limit or ban the use of cell phones while driving. Now, new research indicates that the danger isn't just when you're talking on the phone and driving. Pedestrians who use their phone while crossing the street may be placing themselves at risk. Reporter Stasia DeMarco has more.

DeMARCO:  Even though crossing a city street in the broad daylight seems to most people to be a relatively safe activity, audio distractions such as a hands-free mobile phone can make pedestrians more vulnerable to accidental injuries, and more likely to be struck by a passing car than pedestrians not using these devices.

That's one of the findings in twin studies by psychologist Art Kramer and colleagues at the University of Illinois' Beckman Institute.

Kramer says their aim was also to compare how much extra risk street-crossers face when they are listening to different forms of audio, such as portable music players. He says in order to test young people and older adults as they crossed, researchers used large computer simulations of a real world street-crossing in a lab they call "the Cave."

KRAMER:  "We have a number of virtual reality facilities. One of them is a huge room with huge projectors, projecting on each of the walls. And we're able to take a manual tread mill, put it into the Cave [and] have it control the visual graphics of a street scene in which we can control the number of lanes of traffic, the amount of traffic, the speed of the automobiles, and the gap between the automobiles.

"And we simply had people crossing the street either the way we normally would, without a cell phone or so forth, listening to music on an iPod or talking on a hands-free cell phone, as people often do.

"We asked the question, whether people would have more difficulty getting across the street, whether they would get run over more often - something you are not allowed to do in the real world, of course, and you can in a virtual reality world."
 
DeMARCO:  Kramer says both young and older subjects experienced heightened difficulty crossing the street safely while engaged in conversation on a hands-free cell phone.

KRAMER:  "The students got run over a bit more, the older adults even a bit more than that and had a tough time getting across the street in a timely fashion. And that was true [while using] the hands-free cell phone, but not [while] listening to music. We had an iPod and our subjects could select whatever music they enjoyed listening to."

DeMARCO:  Kramer believes the reason listening to a music player was less hazardous for pedestrian street-crossers than talking on their mobile phones is a difference in the cognitive skills required by each of these activities.

KRAMER:  "And the difference between these two conditions, we speculate, has to do with the difficulty and intensive nature of listening to a conversation and coming up with a coherent answer in the cell phone case. But, of course, in the iPod case, you don't have to listen very intensely to still appreciate the music."
   
DeMARCO:  Kramer says he hopes the research will help raise public awareness that phone-toting pedestrians who talk in the crosswalk are putting themselves - and others around them - at higher-than-normal risk.

This study was published in the journal Accident Analysis & Prevention.

For VOA News, I'm Stasia DeMarco.

Time again for our Website of the Week, when we showcase interesting and innovative online destinations.

ORTM Mauritania (:08 fade and hold under)

That clip is from the shortwave broadcasts of ORTM in Mauritania. Shortwave radio, I'm sorry to report, has been in decline for years now. It's hard to compete with MP3 players, FM radio, and the Internet. But there's still enough to keep David Goren interested. He's a radio producer and engaged shortwave hobbyist, and he posts some of what he hears on Shortwaveology.com.

GOREN:   "It's still a lifeline, and I think one reason why I started Shortwaveology now is, even though the heyday of shortwave radio listening has passed, it's still happening, and it's sort of an interesting moment to look at the history of it, and to look at what remains and why."

Goren's site features a podcast, clips from some interesting stations, and selections from some of his own radio work on shortwave themes, from the presumed spy stations that broadcast nothing but numbers, to the electronic hash of data transmissions, to VOA's legendary jazz host, the late Willis Conover.

For David Goren and a lot of other current and former shortwave listeners, there is a certain magic in the voices and music that scratch their way through thousands of kilometers of space into your radio.

GOREN:  "It's not always dependable. It fades in and out. It varies based on the weather, on sunspots. But what I think that does is that adds a feeling of mystery."

Mysteries of shortwave radio explored at Shortwaveology.com, or get the link from our site, VOAnews.com.

MUSIC:  Llanera aircheck from Radio Tachira, San Cristobal, Venezuela (1999)

You're listening to Our World, the weekly science and technology magazine from VOA News. I'm Art Chimes in Washington. 

Eleven nations have signed a treaty aimed at curbing illegal fishing. As we hear from VOA food and agriculture correspondent Steve Baragona, illegal, unreported and unregulated fishing threatens fish populations worldwide and confounds efforts to rebuild the stocks of the many food fish whose numbers have declined.

BARAGONA:  The new treaty is the first to specifically target ports of call. Countries that sign the treaty will require ships coming into port to document their fishing activities, and fishing vessels will be inspected. Sierra Leone's fisheries minister, Haja Afsatu Kabba, says that will make it harder for violators to find a friendly port.

KABBA:  "If you go to country X, country Y, country A, country B, [they will ask,] 'Where did you catch this fish? Where is the certification? How was it validated? Which port states?' Then they see the irregularities. You are not able to. So it is really effective. Because it's like an on-the-spot check."

BARAGONA:  Sierra Leone was one of eleven countries that signed the new treaty as soon as it was approved by the UN Food and Agriculture Organization last week (Wednesday, Nov. 25). So far, signatories include South American, African, Asian, and European nations, and the United States.

Many of the requirements are already in place in developed nations such as the United States, according international fisheries affairs chief Dean Swanson with the US oceans agency NOAA. He says developed and developing countries often have opposing viewpoints on fisheries issues – but not on this one.

SWANSON:  "The developing countries, many of whom don't have the ability to patrol, nor the capacity to enforce whatever rules they apply there, are sick and tired of fishing vessels engaging in what they see as theft of their resources."

BARAGONA:  Swanson says the treaty provides developing countries with technical and financial assistance so their ports can meet the treaty's enforcement standards. That way violators can't shop around for a port with lax should help stop violators who shop around for ports with lax administration.

The treaty doesn't go into effect until 25 nations have signed on. Swanson says many countries enthusiastically supported the treaty negotiations, so he is optimistic that will happen soon.

Steve Baragona, VOA News, Washington.

And finally today ... limb regeneration. It sounds like science fiction, but actually lots of creatures – including salamanders, starfish, and skates – have the ability to completely re-grow a lost or damaged limb or tail. Scientists are studying this ability in a diverse group of species to learn which genes control limb re-growth, why we humans have lost this useful talent, and how we might someday get it back.

VOA's Julie Taboh has the story.

TABOH:  Randy Dahn is a research scientist at the Mount Desert Island Biological Laboratory, a non-profit biomedical research facility near Bar Harbor, Maine.

Dahn and his colleagues are studying primitive vertebrates such as skates, which are closely related to sharks and sting rays. They amputate the animals' fins and then study the genetics of how they re-grow them.

DAHN:  ""So once we understand, we can compare and contrast how all these different groups accomplish this feat and then we can then apply that knowledge to higher vertebrates like humans and mice."

TABOH:  The research builds on decades of study of how animals like salamanders re-grow their limbs. Dahn says scientists already have a pretty good understanding of how the animals' tissues interact with each another during this process. But the real challenge he says, is to understand what's happening at the molecular level:

DAHN:  "So right now we're trying to figure out what genes drive this process and once we understand that, we can understand why humans fail to regenerate their limbs and then hopefully - through genetic trickery - restore that ability."

TABOH:  Regenerative medicine was the topic of a recent symposium at Walter Reed Army Medical Center in Washington, D.C.

One of the guest speakers at the event was Dr. Roy Aaron, an orthopedic surgeon and director of the Center for Restorative and Regenerative Medicine at Brown University in Providence, Rhode Island.

Dr. Aaron says that while amphibians, such as the Mexican salamander, can regenerate an entire limb, no mammals are currently capable of doing that.

AARON:  "Mammals form a little mass called the Blastima, and then it scars, and quiets down, and doesn't grow."

TABOH:  Aaron points out that humans do have the ability to re-integrate certain organs, such as the liver and skin, when they have been surgically transplanted into their bodies. But he says accepting grafted tissue is not nearly as complicated a process as re-growing a body part as complex as an entire limb:

TABOH:  Another guest speaker at the Walter Reed symposium, Major General George Weightman, is the associate director of the Institute for Regenerative Rehabilitation at Wake Forest University's Baptist Medical Center. Weightman shares the view of others in the field that limb regeneration is an extraordinarily complex process:

WEIGHTMAN:  "If you think about it, there's bone, there's bone marrow inside the bone, there's cartilage, there's tendon, there's blood vessels there's nerves, there's muscles, there's skin, and how do you get them all not only to grow together and to recognize each other in the same environment, but how to function as a limb?"

TABOH:  Weightman predicts that as scientists learn more about growing individual tissues, their first goal will be to re-grow single fingers before they attempt to re-grow a whole limb:

WEIGHTMAN:  "You've probably seen the pictures of growing the end of a finger tip back; we can do that now, but much past a centimeter, things just stop."

TABOH:  And Weightman says even if we do figure out how to keep the process going, the question then will be whether the regeneration is carried out in the lab or on the amputee's limb:

WEIGHTMAN:  "So the question is whether we'll be able to grow a limb, and then put it in a bioreactor, and then transplant it on a person; that's one strategy. Another strategy would be basically to put, if you will, a magic goop on the end of an amputee that recognizes where it is and what the needs are to generate that limb.

TABOH:  And when do our experts predict human limb regeneration will become possible? Research scientist Randy Dahn is optimistic:

DAHN:  "I think a reasonable goal is to understand some of the underlying molecular basis in the next five-to-ten years and I think it'll be a fairly rapid transition then to testing these ideas in mice and chickens, which are closely related to humans. I don't want to put a number on it, but certainly well within our lifetimes."

TABOH:  But Brown University's Roy Aaron believes it's going to take several lifetimes before limb regeneration becomes a medical reality. He says technological advances and improved surgical efforts are currently the main focus of regenerative medicine:

AARON:  "Some of the new work in prosthetics; micro-processor controlled with linkages to the nervous system are way ahead of the biological opportunities of regeneration."

TABOH:  Julie Taboh, VOA News, Washington.

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That's our show for this week.

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