SCIENCE
NEWS
This Week

would have to be built in space from lunar material or asteroids.

In contrast, Angel’s proposed flyers, which include shades made of transparent film and riddled with holes, can be built and assembled on Earth, he asserts.

Rather than requiring rocket fuel, which could further contribute to global warming, the flyers would be accelerated into space by a large magnetic field applied along 2,000-m-long tracks. With each such launch sending out 800,000 flyers, the project would require 20 million launches over a decade.

The flyers would rely on ion propulsion to reach their destination—a position between the sun and Earth in which the craft would take the same amount of time to orbit the sun as Earth does. They would then maintain a fixed position relative to Earth and shade it for about 50 years.

The flyers would need to continuously modify their trajectories. The pressure of sunlight on a trio of tiltable solar reflectors, embedded with electronics, would automatically redirect each craft, keeping the cloud intact or dispersing it as needed.

Several scientists say that there are less-expensive and easier ways to reduce global warming. Aluminized Mylar stretched across the ground or white paint covering large areas to reflect visible light from Earth

into space “would be vastly cheaper,” says astronomer Webster Cash of the University of Colorado at Boulder.

“It makes much more economic sense to find ways to address the climate problem directly by reducing the pollution that causes it,” says climatologist James Hansen, director of NASA’s Goddard Institute for Space Studies in New York City.

No word has come yet on what Angel’s wife thinks. —R. COWEN

Helping Hands
Brief rehab method aids
arm activity after stroke

Stroke survivors who have difficulty using an arm or a hand experience lasting mobility gains after completing an unusual 2-week rehabilitation program, a new study finds. STATS

Constraint-induced movement therapy (CIMT) exercises a weakened limb repetitively while restraining the better-functioning limb with either a sling or a mitt for much of the day.

Among patients who had had strokes within the previous 3 to 9 months, 2 weeks of clinician-supervised CIMT produced more mobility in their stroke-weakened arms over the ensuing year than standard rehabilitation approaches did, reports a team led by neuroscientist Steven L. Wolf of Emory University School of Medicine in Atlanta. Wolf and his coworkers present their findings in the Nov. 1 Journal of the American Medical Association.

“CIMT should be considered as a valuable form of rehabilitation for stroke patients who have lost arm function,” Wolf says. He estimates that as many as 30 percent of stroke survivors can benefit from this intervention.

In the United States each year, about 566,000 people experience arm or hand impairments due to stroke-related brain damage. For most, these mobility difficulties last at least 3 months.

The researchers randomly assigned 222 stroke patients, recruited from seven hospitals across the country, to receive either CIMT or standard care, which ranged from no treatment to various occupational and physical therapies.

Over 2 weeks, each CIMT participant wore a mitt on his or her less-affected hand for most waking hours. On each weekday, the person received up to 6 hours of training in using the stroke-impaired hand and arm to perform basic tasks, such as writing and eating.

Wolf’s team evaluated each patient

immediately after the assigned treatment, and again 4, 8, and 12 months later. During those assessments, patients performed tasks designed to measure arm and hand dexterity and described how well and how often they used their impaired limbs in daily activities. Of the initial participants, 169 completed 12-month evaluations.

Mobility in the affected arm and hand improved for both groups. However, the CIMT participants displayed substantially greater advances immediately after treatment than the standard-care group did, the scientists say. Mobility advantages for the CIMT group over the other participants increased steadily during the next year.

Study coauthor Edward Taub of the University of Alabama in Birmingham had previously directed brain-imaging studies in small groups of stroke patients and in monkeys with experimentally severed arm nerves. The findings indicated that CIMT

stimulates brain reorganization
that fosters arm rehabilitation.
In the 1980s, animal rights
activists succeeded in halting
Taub’s work with monkeys.
The new investigation
underscores the value of the
initial monkey research, says
neurologist John R. Marler of
the National Institute of Neu-
rological Disorders and Stroke
in Bethesda, Md. Wolf’s study

“shows that it’s possible to harness the remarkable plasticity in the brain to improve the lives of stroke patients,” Marler remarks. —B. BOWER

566,000

Yearly number of U.S. stroke patients who lose arm or hand mobility

Dribble Quibble
Experiments find that
new basketball gets slick

COOLING CONCEPT Miniature flyers made of transparent film would deflect sunlight from Earth. Three solar-reflecting tabs on each flyer direct its course. This illustration shows background starlight blurred into doughnuts by the film.

A dispute in professional basketball about a new ball has bounced its way into a physics lab. A study launched last month at the University of Texas at Arlington compares a controversial plastic ball introduced in preseason games this summer by the National Basketball Association (NBA) with the previous standard—a leather-covered ball. The official basketball season, the first in which the new ball will be used, began this week.

So far, the Texas experiments indicate that the new ball bounces less elastically, veers more when it bounces, and becomes more slippery when damp than does the official leather ball of the past 35 years.

Many NBA players have griped about the new ball since teams began using it.

“The most significant finding is the slickness of the ball,” says University of Texas physicist James L. Horwitz. He, physicist Kaushik De, and their colleagues gauged friction for both new and old balls