SCIENCE
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This Week
“We went through pains to be able to say
that [the improvements] were statistically
linked to the brain stimulation,” says Schiff,
coauthor of a report describing the case in
the Aug. 2 Nature.
Schiff, Rezai, and their colleagues
received a special exemption from the Food
and Drug Administration to perform the
surgery. The team plans to enroll 11 more
minimally conscious patients in the study.
“It’s very important people realize this
patient was not in a coma—he wasn’t
woken from a coma,” says Michael Shan-dlen, a neurologist at the University of
Washington Medical School in Seattle.
Patients in comas and in persistent vegetative states have more-severe brain damage that would preclude the improvements
seen in the study patient, he says.
Deep-brain stimulation is sometimes
applied, in different parts of the brain, to
patients with Parkinson’s disease, intractable
obsessive-compulsive disorder, or depression. Rezai estimates that some 40,000 people worldwide have the devices. —B. VASTAG
Asian Forecast:
Hazy, Warmer
Clouds of pollution heat
lower atmosphere
Hanimadhoo, a remote island in the Maldives archipelago southwest of India’s
southern tip. During the flights, the scientists measured temperature, humidity, and
intensity of sunlight at various wavelengths
nearly simultaneously at several altitudes
over the island. They also gathered data at
a land-based weather station.
During the last 2 weeks of the field test,
winds were bringing air masses from India
to the island, says Ramanathan. On those
days, the array of data suggests that each
cubic centimeter of air between the altitudes of 1 kilometer and 3 km contained
about 2,500 particles of smoke and soot.
Overall, the temperature of the air
between altitudes of 500 meters and 3 km
was about 0.5°C warmer than it would
have been without the pollution, the
researchers estimate. About 90 percent of
that heating can be attributed to soot, they
report in the Aug. 2 Nature.
Between 1950 and 2000, brown clouds
warmed the lower atmosphere’s yearly average temperature as much as 0.8°C in the
region, the team estimates. During the same
period, increased atmospheric concentrations of greenhouse gases such as carbon
dioxide had a comparable effect, says
Ramanathan. Overall, the lower atmosphere
in the region has warmed about 0.25°C each
decade since 1950, causing major melting of
many Himalayan glaciers.
“Scientists used to think of atmospheric
brown clouds as masking global warming” by cooling the air at ground level,
Ramanathan notes. “Our new findings
show that [brown clouds and greenhouse
gases] actually are working together” to
heat the atmosphere.
Results of this field study demonstrate
that similar initiatives using airborne drones
are essential for advancing climate research,
says Peter Pilewskie, an atmospheric scientist at the University of Colorado at Boulder. The data from such research, as well as
those gathered by aerosol-detecting satellites, will enable scientists to better assess
the effect of airborne particles on global climate, he notes in a comment appearing with
the new study. —S. PERKINS
G Whiz!
Craft identifies source
of faint Saturnian ring
Among Saturn’s shimmering ice belts, the
planet’s G ring has proved the most puzzling. The very location of this faint, narrow
ring, well beyond the planet’s main ring system, has been a riddle ever since the two
Voyager spacecraft spied it in 1980. The
G ring lies more than 15,000 kilometers
from any Saturnian moon. It’s neither
flanked by bodies that might corral its particles, as the moons Pandora and Prometheus
do for the F ring, nor close to an object that
could shed particles to populate the ring, as
Enceladus does for the E ring.
Now, in one fell swoop, the Saturn-tour-ing Cassini spacecraft has discovered the
source of the G ring and identified the body
whose gravity holds the source material
together.
Cassini images taken in 2004 and 2005
showed a bright arc just inside the G ring.
The 250-km-wide crescent is about one-twentieth the width of the G ring, report
Matt Hedman of Cornell University and his
The murky clouds of smoke and soot that
blanket many regions of Asia have heated
the lower atmosphere there in recent
decades as much as increases in carbon
dioxide and other greenhouse gases have,
a new field study suggests.
Scientists have long argued about the net
climatic effect of aerosols such as dust,
smoke, and soot. Light-colored aerosols scatter much of the light that strikes them, some
of it back to space, says V. Ram Ramanathan,
a climate scientist at the Scripps Institution
of Oceanography in La Jolla, Calif. However, dark aerosols such as soot can absorb
much of the incoming radiation, warming
themselves and the air around them. Current estimates of the overall effect of light-dark mixtures—including the so-called
atmospheric brown clouds of pollution
found in parts of Asia—are based largely on
computer simulations, says Ramanathan.
Now, he and his colleagues weigh in on
the debate. In March 2006, they repeatedly
steered a squadron of instrumented drones
through clouds of pollution wafting over
RIVER OF HAZE Dense “brown clouds” of pollution that smother much of Asia, such as the
gray haze wafting over northern India’s Ganges River in this Dec. 17, 2004, image, boost the
lower atmosphere’s temperature, a new study suggests.
J. ALLEN/NASA
