MUSIC: "Our World" theme
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
ThebanMappingProject.com
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
ThebanMappingProject.com, or get the link to this and more than 200 other
Websites of the Week from our site, voanews.com/ourworld.
MUSIC: Boston Pops
Orchestra — "The Raiders' March"
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, brain-map.org, 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.
MUSIC: "Our World" theme
That's our show for this week. If you'd like to get in
touch, email us at ourworld@voanews.com. 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 voanews.com/ourworld or on your radio next Saturday and Sunday as we check out the latest in science and technology ... in Our World.
