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Our World — 26 July 2008

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This week on "Our World" ... A climate-change controversy hits Congress ... studying how animals navigate using Earth's magnetic field ... and the value of posting science data online.

JONES: "About 1,000 researchers every day access wthe data in the database. There've been 160 different studies or scientific publications that have cited our work."

Those stories, the sounds of science, and more. I'm Art Chimes. Welcome to VOA's science and technology magazine, "Our World."

On Tuesday, the Senate Environment Committee spent a couple of hours considering the state of climate change science and the response of the Bush Administration.

At a hearing on Capitol Hill, a former administration official, and climate scientists with decidedly different views of the causes of global warming, were among those taking turns at the microphone to address the Senate lawmakers.

Roy Spencer of the University of Alabama is a former NASA climate researcher. He rejects the mainstream view that human activity is causing global warming. He told the committee that the latest evidence points to natural causes, and that the situation isn't as bad as the Intergovernmental Panel on Climate Change, the IPCC, has projected.

SPENCER: "When translated into an estimate of future global warming, it would be less than one degree [celsius] by 2100, well below the range of the IPCC's estimates of future warming. That also means that the radiative forcing being caused by the CO2 we put into the atmosphere is not nearly enough to explain the warming we've seen in the last 100 years. There must be also some sort of natural warming mechanism involved."

Roy Spencer's analysis of climate data leads him to conclude that cloud fluctuations and other natural phenomena are mainly responsible for the recent warming trend.

Spencer says the majority of climate researchers who disagree with him are failing to properly account for the role of clouds in their analyses.

Kevin Trenberth of the National Center for Atmospheric Research doesn't discount natural factors in climate change. He says human-caused climate change plus natural climate variability can make for some extreme weather events in places like Myanmar (Burma) and the Philippines.

TRENBERTH: "And so these things happen from time to time and they affect different areas. But they don't affect everywhere all at once. The same thing tends to happen with droughts. The droughts move around from one year to the next and it's easy to say, well maybe this is natural variability, and natural variability is playing a role. The thing is that we've got, in fact, nowadays global warming and natural variability going hand-in-hand."

The hearing took a political turn in the questioning of former Environmental Protection Agency official Jason Burnett.

Burnett contradicted his former boss, EPA Administrator Stephen Johnson, over whether the White House was involved in a decision on whether to allow California to set its own, tougher air quality standards. Johnson told Senators in January that he decided on his own not to allow California to set its own rules.

But at Tuesday's hearing, former EPA official Jason Burnett contradicted Johnson, saying the White House had effectively ordered EPA to deny California's request.

As our bodies age, many changes occur. We need fewer calories to stay well-nourished, our hormone levels change. Now, new research from the Harvard Medical School indicates that older people also need less sleep. Health reporter Rose Hoban has our story.

HOBAN: Dr. Elizabeth Klerman studies sleep patterns. She led a study to compare older peoples' sleep to that of younger people, with a group of senior citizens and subjects who were mostly in their 20s. Klerman says all the participants were asked to keep a diary of how much they slept at home.

KLERMAN: "So some of the younger subjects slept as little as six and a half hours [a night]. And some of them slept as much as 10 hours, because they said that's how much sleep they need. And we monitor that while we are at home, and we used that to say this is what they thought they needed."

HOBAN: Then Klerman and her colleagues had the subjects sleep at the hospital for up to a week, where they were monitored throughout the night. The researchers gave everyone more opportunity to sleep, by telling them to stay in bed in the dark, for up to 16 hours a day.

KLERMAN: "For the first day of this, both the older and younger subjects slept considerably more than they did at home. And then, over the next couple of days the amount of sleep that they got increased a lot and then it gradually decreased to what looked like a steady state level. That's reflective of a set point around which the body is trying to regulate."

HOBAN: Once subjects were sleeping the right amount of time for them, Klerman found that on average, the older people slept for about an hour and a half less than the younger people. Klerman also found that it took them more time to fall asleep.

Klerman says they're not sure why this happens. She says part of it could be that as we age, the threshold for falling asleep changes.

KLERMAN: "Think about children who are three and five years old. When they fall asleep, they fall asleep. You can lift them out of their car seat, change their pajamas and put them into bed and they'll remain asleep, right? They have a very different threshold than in older people, whom it's harder for them to fall asleep and they're more easily awoken. They still have a sleep drive, they still need sleep, but the threshold for remaining asleep may be different in older and younger people."

HOBAN: Klerman says her next set of experiments will try to find this sleep threshold in older and younger people.

Her research is published in the journal Current Biology. I'm Rose Hoban.

Animals as diverse as birds, sea turtles, bats, and bees can sense the Earth's magnetic field and use it as a guide in navigation. For some years now, scientists have been trying to figure out how they do it. Now, a new study has identified a unique molecule that might hold the key to this special ability. Véronique LaCapra brings us this story.

LaCAPRA: Movement in the Earth's iron core produces a magnetic field around the planet. Humans can use the magnetized needle of a compass to navigate. But some animals can perceive this magnetic field directly to orient themselves to their surroundings.

The exact mechanism underlying this remarkable magneto-sensitivity has remained a mystery.

To investigate this phenomenon, scientists needed a test species.

REPPERT: "We wanted an animal where we could manipulate various components of their internal chemistry."

LaCAPRA: Dr. Steve Reppert is a neurobiologist at the University of Massachusetts Medical School.

REPPERT: "And one of the best animals to use is the fruit fly because you can manipulate genetically various aspects of the fruit fly's biology."

LaCAPRA: The first step was to confirm that fruit flies were able to sense a magnetic field. The researchers developed an elegant experimental apparatus: a T-shaped maze. Picture the letter "T" made out of hollow tubes, with a metal coil at the end of each horizontal arm. By running an electric current through the coils, the scientists could generate a magnetic field in either arm of the "T."

To run the tests, the researchers put fruit flies into the maze, starting at the bottom.

REPPERT: "The flies had a choice then, when they were in this apparatus. They could either go to the left or to the right, and in one instance they would go towards the magnetic field, and in the other they would go away from it."

LaCAPRA: Next the scientists trained the flies by putting some sugar at the end of the magnetized arm of the T-maze. Then they took the sugar away, and tested whether the flies would still go towards the magnetic field, expecting a sweet reward.

REPPERT: "What we wanted to do was to see whether the flies would associate the food reward with the magnetic field. And in fact the flies did, and it gave us a much more prominent response of the flies to the magnetic field."

LaCAPRA: Now that Reppert and his colleagues were sure the flies could detect a magnetic field, they wanted to figure out how they were doing it. Previous research had suggested that animals may use special light receptors, called cryptochromes.

REPPERT: "Cryptochromes are proteins that function as blue light photoreceptors in the fruit fly."

LaCAPRA: In ordinary light conditions, the cryptochromes in a fruit fly's eye and brain are exposed to the full spectrum of light, from blue to green to red.

The blue light part of the spectrum activates the cryptochromes, causing them to undergo specific chemical responses that the flies need for their biological clock to function.

To test whether cryptochromes also play a role in the fruit fly's ability to sense magnetic fields, and the researchers put a light filter over the T-maze.

REPPERT: "So the animal still could see red light and green light but the blue and ultraviolet shorter wavelengths were blocked."

And in that instance, the magneto-receptive response was totally gone.

LaCAPRA: Reppert and his colleagues had shown that the flies needed blue light to detect a magnetic field. But the researchers still had to make a definitive link between magneto-sensitivity and cryptochromes.

To do this they used fruit flies with genetic mutations that effectively disabled the cryptochrome gene.

REPPERT: "And then we could ask the question OK, since the gene is no longer working, what happens to the magneto-sensitive response? Prediction was it would go away, and indeed it did."

LaCAPRA: Migratory birds, sea turtles, and other animals that use the earth's magnetic field to navigate also have cryptochromes, albeit different ones from those found in fruit flies.

Reppert says that the next challenge will be to investigate whether the cryptochromes of other species play a similar role to those of the fruit fly in sensing magnetic fields.

REPPERT: "We have the possibility in the fly to actually take any animal's cryptochrome, and to put it in as a trans-gene, and to ask the question in the fly, can it function as a magneto-sensitive molecule and we're very excited about that potential."

LaCAPRA: Reppert's current findings were published in the journal Nature. I'm Véronique LaCapra.

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

The latest Indiana Jones film is likely to remind people about the thrill of archaeology. Well, maybe not the romance and bullwhip-cracking adventure of the Harrison Ford version, but the excitement of discovering the past is still there.

The Middle East has always been a rewarding place for excavating the past. It certainly has been for Dr. Kent Weeks, who has spent decades mapping the burial place of Egypt's Pharaohs at Thebes, the capital of ancient Egypt. In 2000, he and his colleagues published an atlas that mapped out the so-called Valley of the Kings.

WEEKS: "And it struck us at that time that it would be especially useful if, instead of just publishing a hard copy of the atlas, we could also put it up online. And it struck us at that time it would be especially useful if, instead of just publishing a hard copy of the Atlas, we could also put it up online. And so we established a website that put our atlas up and, well, as of last count, around 8,500 color photographs of the decorations on their walls."

So now you, too, can travel, virtually, to ancient Egypt at

This is a very feature-rich site, with a tremendous level of detail. And it's designed for a wide range of visitors.

WEEKS: "In other words, the kind of technical data that an Egyptologist requires is there, but it's presented in a way that makes it fun and exciting for school kids as well. And it's one of the reasons that our website has been adopted as part of the curriculum in about 130 different countries."

For non-specialists, there are short video tours of each of the tombs in the Valley of the Kings, designed so that even a teenager can understand them. And Weeks says there's more to come.

WEEKS: "The Valley of the Queens is going up on our website. We've mapped it completely and are photographing it. That's going up in a couple of weeks.The Valley of the Queens is going up on our website. We've mapped it completely and are photographing it. That's going up in a couple of weeks. There are village sites, mortuary temples, prehistoric sites, early Christian churches, early mosques, a whole array of archaeological materials. It probably covers more than 3, 4, 500,000 years of ancient cultures."

Ancient Egypt at the click of a mouse at, or get the link to this and more than 200 other Websites of the Week from our site,

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It's VOA's science and technology magazine, Our World. I'm Art Chimes in Washington.

A couple of years ago we featured a Website of the Week called the Allen Brain Atlas. The Allen Institute for Brain Science uses the web as a platform to publish information about the link between specific genes and particular locations and functions in the brain.

This month the website,, began to include information about the spinal cord. They're working with mouse, not human, brains and spinal cords. But as we'll hear from the institute's chief scientific officer, Allan Jones, there is a lot that mice can tell researchers, whose real interest is humans.

JONES: What we do at the Allen Institute is to create data that's at the cellular level. So we actually look at thin sections of tissue — in this case it's the spinal cord — and we see where genes are turned on in those tissues. We'll have 2,000 genes worth, which is 60,000 sections that's available to researchers around the world for free. It's almost like a virtual microscope sitting in front of them, where they can actually zoom in and see where genes are turned on in individual cells.

Q When we talked about the brain a couple of years ago, you told me I believe that something like 90 percent of the information of the genes are going to be essentially the same. And is that true of spinal cord as well?

JONES: Yes, so at our genome level, basically about 90 percent of our genes have a direct, identifiable counterpart, in the mouse. So it's actually a great model system. And one would expect all the same things — the spinal cord in the human, just like in the mouse, it's enervating and both receiving sensory information and then doing a lot of the basic machinery of living, controlling breathing, controlling digestion. All of those things that I think people will relate to happen in a mouse just like they happen in humans."

Q: So that means this database for the mouse can be used by researchers who are looking, actually, at human disease?

JONES: "Precisely. There are also some very good mouse models of some diseases, such as Lou Gehrig's disease, ALS. There are of course mouse models for spinal cord injury as well."

Q: How much difference does the Web make in projects like this?

JONES: "I think the advances in both high-speed Internet, the ability to pull large image data down across the Web, have enabled this. You couldn't have done something like this before. Pretty much, a researcher anywhere in the world can, with a few clicks of a mouse, come in and view this image data at high resolution. It is remarkable."

Q: I won't ask you to predict what results that investigators are going to get from using this data on the spinal cord, but the brain data has been online for two years now. Do you have any feedback on how it's been used?

JONES: "Yeah that's a fantastic question. So we do know that about 1,000 researchers every day come in and access the data in the database. One other way we can track our usage and the impact of this data: there've been 160 different studies or scientific publications that have cited our work, meaning that they're probably using the [Allen Brain Atlas] data in some way. And those range from people studying Parkinson's disease to Alzheimer's to schizophrenia to epilepsy to memory, sleep, you name it. Just all sorts of different disciplines using it. And it's really exciting because it's exactly what we hoped for, which is people using the data in ways that we never expected."

The largest acoustics conference ever was held in Paris this month, co-sponsored by the Acoustical Society of America. The event showcases advances in the study and use of sound. As we hear from reporter Eric Libby, the topics discussed cover the spectrum from music to medicine to marine mammals.

LIBBY: That could be the sound of a backed up toilet or an old video game, but it is actually ice cracking and breaking off from Antarctica, recorded from the sea floor and altered so that human ears could hear it. According to Alexander Gavrilov of Australia's Curtin University of Technology, these sounds can measure the amount of ice Antarctica is losing, an indicator of global warming.

Gavrilov was just one of the presenters at the Acoustics 2008 conference. Gilles Daigle, a spokesman for the event, says this conference was unprecedented in its size.

DAIGLE: "Up until now the largest attendance was about 2,300 people. This meeting we are just one person shy of 5000."

LIBBY: Daigle says that medical acoustics is a hot topic this year. Duke University's Kathy Nightingale is using high-energy sound to measure the stiffness of human organs. She bombards specific areas of tissue with sound to jiggle it back and forth the distance of a human hair. Nightingale she told conference delegates that this jiggling can help doctors diagnosis diseases like cirrhosis in the liver.

NIGHTINGALE: "Historically, clinicians have used their fingers to palpate tissue to look for regions of pathology, for example a breast exam. And so the idea is that most tissues that are palpable are either larger masses or they are closer to the surface, but if you could effectively extend the physician's finger inside the tissue you might be able to feel regions of pathology earlier as they develop and also that are smaller where you might have better chance of treating them."

LIBBY: Another popular area of sound research is animal calls. Frederic Theunissen and his colleagues at the Berkeley Field Station for Behavioral Research in California listen to the sophisticated vocabulary of spotted hyenas. Hyenas live in social groups that communicate through giggles, whoops, and groans.

Theunissen's group is particularly interested in deciphering those groans. They present the hyenas with objects like bones, cages and cubs, and record the sounds the animals make to each. This is the call to the empty cage. (hyena sounds)

This is the call to a cub. (hyena sounds)

Theunissen's group analyzes the differences in these groans in hopes that understanding hyena communication will help people appreciate this often-maligned animal.

But giggles, groans, and whoops are not unique to hyenas; they can also be found in a lot of school classrooms. When sounds bounce off the walls, the resulting reverberations can blend with other speech, making it difficult to hear the teacher. Frank Iglehart of The Clarke School for the Deaf in Massachusetts wants to improve classroom design by reducing the noise and reverberations. He says this is especially important for children with hearing problems, who may only understand one out of every four words in a typical classroom.

IGLEHART: "When you go to the children who have greater hearing loss, particularly children with cochlear implants, when those children are in a quiet environment, they perform beautifully. But when they're put into any kind of reverberant environment, like your typical classroom, their hearing abilities just plummet."

LIBBY: Iglehart says using carpet, sound-absorbing tiles, and architectural changes make it so that people with hearing loss can hear almost all of the words.

Sound research is an active and expansive field with countless practical applications. It also opens our ears to all of the knowledge and pleasure that can come from sound. This is Eric Libby in Washington.

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That's our show for this week. If you'd like to get in touch, email us at Or use the postal address —

Our World
Voice of America
Washington, DC 20237 USA.

Rob Sivak edited the show. Eva Nenicka is the technical director. And this is Art Chimes, inviting you to join us online at or on your radio next Saturday and Sunday as we check out the latest in science and technology ... in Our World.