Plan to Limit Emissions

Of Carbon Dioxide Mapped

The United States could keep carbon dioxide emissions from rising over the next 50 years by using several existing technologies, according to a paper published by two Princeton University professors in Friday's edition of Science.

Stephen W. Pacala and Robert H. Socolow identified 15 technologies that could be used to curb pollution, including wind-powered generation of electricity, conversion of 1,400 coal-fired plants to natural gas, capturing and storing emissions from 800 coal-powered plants, and doubling global nuclear power plant capacity to replace coal-based electricity. Carbon dioxide, much of it produced from fossil fuels such as coal, is thought to be a major contributor to global warming.

"There's lots you can do," said Socolow, who teaches in the department of mechanical and aerospace engineering. "You will not need magic bullets that you don't have at the present time."

At present, 7 billion tons of carbon are emitted into the atmosphere annually, which is more than twice the amount that can be absorbed by oceans and forests. This amount is expected to double over the next half-century. Under the Princeton scenario, emissions would stay constant, with a goal of reducing the total to 3 billion tons a year in 100 years.

If governments fail to act, Socolow said, the concentration of carbon dioxide in the atmosphere will triple in 50 years. "Keeping it below doubling is a heroic task," he said.

The scientists did not estimate how much it would cost to implement their proposal, though they said it would produce some economic benefits by creating new industries and reducing American dependence on foreign oil.

Dan Riedinger, a spokesman for the Edison Electric Institute, said the paper reflected a "pie in the sky" analysis. He said the recommendation for retrofitting coal-fired plants did not take into account the fact that the United States is already straining its existing natural gas reserves and pipeline capacity. Such a switch would force the power sector to monopolize the nation's domestic natural gas resources at the expense of manufacturing, agriculture and home heating, he said.

"They're not factoring in the large-scale economic and political obstacles in doing such a large-scale conversion," Riedinger said. "Our economy could not absorb this kind of major shift."

-- Juliet Eilperin

U.-Va. Researchers Develop

Stronger Type of Steel

Two University of Virginia researchers have discovered a way to make nonmagnetic amorphous steel that is three times as strong as conventional steel and potentially could be used for such products as ships' hulls and automobiles.

Physics professor Joseph Poon said he and Gary Shiflet, a professor of materials science, spiked molten steel with large atoms of yttrium or other rare-earth elements, creating a "jamming effect" to keep the iron from coming together in its normal crystalline structure.

As an amorphous "glass," the steel is about three times as strong as conventional steel, offering potential savings for companies such as automakers, which can use far less to achieve the same resilience as crystalline steel. Poon and Shiflet can make amorphous steel that is almost half an inch thick, twice as thick as any previous similar product.

Because the steel is nonmagnetic, it offers new stealth possibilities for ships, ordinarily detectable by their magnetic fields, and the ability for a ship to ignore magnetically detonated mines. The research, reported in the latest issue of the Journal of Materials Research, was carried out under a grant from the Defense Department's Defense Advanced Research Projects Agency.

The problem now, explained Shiflet, is that the new steel is brittle, with a tendency to shatter: "We'd like to have some ability to bend it at room temperature," he said in a telephone interview.

One way is to add other elements "to weaken the bonds and get more 'give,' " Shiflet said. "You sacrifice some strength, but get the flexibility." He and Poon are also reheating the steel until it starts to recrystallize at 1,100 degrees Fahrenheit: "You try to control the process so you still have an amorphous matrix with crystals embedded."

-- Guy Gugliotta

Blocked Brain Circuit Turns

Monkeys Into Workaholics

Monkeys worked harder for rewards when scientists temporarily blocked a brain circuit that told the animals how close the reward was, according to a paper to be published this week in the Proceedings of the National Academy of Sciences.

The technique was effectively a fix for one form of procrastination, scientists concluded. No one is considering treating humans or animals for being lazy, but the new research elegantly showed how the brain's reward circuitry works and may shed light on certain mental illnesses.

"The monkeys became extreme workaholics," said Barry J. Richmond, one of the authors and a researcher at the National Institute of Mental Health, in a description of the work issued by the federal institution.

Where the monkeys had slacked off on a computer test when they knew a tasty reward was a long time away, they worked harder when scientists temporarily blocked a reward circuit in the brain involving the neurotransmitter dopamine.

"Like people, they tend to procrastinate when they know they will have to do more work before getting a reward," Richmond said.

Once the animals lost the sense that a tasty reward was far away or near, they applied themselves to the computer test as if the reward was near. Scientists believe the work can help shed light on why some people with certain mental illnesses are unmotivated to work, while other illnesses cause people to apply themselves obsessively to certain tasks.

-- Shankar Vedantam