Post
Monday, May 30, 2005; A08

Solar Flare Confounds Scientists

As revelers prepared to celebrate President Bush's second inauguration on Jan. 20, the most intense burst of solar radiation in 50 years sped to Earth after an enormous solar flare. The radiation reached Earth in 15 minutes -- much faster than the two or more hours normally required, researchers said last week.

The super-fast-moving flare set off radiation monitors worldwide and upset detectors on spacecraft. It also upset theories of space weather and highlighted the potential dangers to interplanetary astronauts from radiation storms.

Richard Mewaldt of the California Institute of Technology said the speed of the radiation burst was troubling because "it's too fast to respond with much warning to astronauts or spacecraft that might be outside Earth's protective magnetosphere." He added: "We need to develop the ability to predict flares in advance if we are hoping to send humans to explore our solar system."

The flare, at 2 a.m. Eastern time, was caused by the buildup and sudden release of magnetic stress in the atmosphere above a sunspot. Such flares are the most powerful explosions known in the solar system.

According to presentations at a meeting of the American Geophysical Union last week, the energized protons began reaching Earth only minutes after the first sign of the flare. The researchers said they currently have no way to predict the energy flow into and out of solar flares.

-- Marc Kaufman

Despite a dramatic increase in the psychiatric treatment of emotional disorders over the past decade, there has been no decrease in the rate of suicidal thoughts and behavior among adults, according to a highly respected federal survey.

People who attempt suicide were far more likely to be treated, especially with antidepressants such as Prozac, Paxil and Zoloft, in 2001-2003 compared with 1990-1992. But the rates of suicidal ideation, gestures and attempts remained essentially unchanged, said researchers from Harvard Medical School and elsewhere, who published their findings last week in the Journal of the American Medical Association.

The striking finding may have several explanations, they said: Reductions in suicidal behavior as a result of treatment might be offset by increases in such behavior triggered by the drugs in some people -- the Food and Drug Administration last year warned of such effects in children, but has not said the problem affects adults.

It is possible that suicidal behavior would have increased without the growth in treatment, or that patients got inadequate treatment. It is also possible that antidepressants are not good at reducing suicidal behavior, even when prescribed correctly.

The analysis was based on a recent survey of 9,708 adults and a comparable survey in the early 1990s. It was primarily funded by the National Institute of Mental Health.

-- Shankar Vedantam

Oil is a fossil, the transformed remains of plants and animals that lived millions of years ago. How many millions? Curiously, that is a question scientists have not been able to answer very well.

Now, a pair of geochemists at the University of Alberta have devised a way to estimate the age of oil much more accurately. Their findings were reported in the May 27 issue of the journal Science.

David Selby and Robert A. Creaser used the rate of decay of two extremely rare metals -- rhenium and osmium -- as their clock. The elements are present in seawater but under certain conditions concentrate in bottom sediments, including ones loaded with decaying organic matter that ultimately ends up as oil.

Normally, there's much less of the osmium isotope Os-187 than of its slightly heavier sister, Os-188. In ancient seawater, the ratio was about 1 to 3.

This ratio isn't necessarily constant, however. That's because one way that Os-187 forms is by the decay of a radioactive isotope of rhenium, Re-187. This doesn't happen fast; the half-life of rhenium is 42 billion years. Nevertheless, if there is rhenium around, the amount of Os-187 can rise very slowly.

The researchers took samples from the oil sand deposits of Alberta, believed to have been formed from organic matter laid down about 112 million years ago in the Cretaceous Period, and measured the ratio of Os-187 to Os-188. It was 1.4 to 1.

Using the known rate of radioactive rhenium decay, they calculated that the plants and animals that became the Canadian oil may have been deposited much earlier -- as early as the Devonian Period, which ended 360 million years ago.

Although oil's age alone is not of great interest to petroleum companies, the light it sheds on the history of oil-bearing formations is.

"One of the things they want to know is when [oil] reservoir-filling occurred, what the actual trapping mechanism was, and what has allowed the oil to move. This will help them understand the whole system better," Selby said.

-- David Brown