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WASHINGTON, May 11 (Xinhua) -- NASA's Dawn spacecraft has obtained its first image of the giant asteroid Vesta, which will help fine-tune navigation during its approach, the U.S. space agency announced Wednesday.Dawn expects to achieve orbit around Vesta on July 16, when the asteroid is about 117 million miles from Earth.The image from Dawn's framing cameras was taken on May 3 when the spacecraft began its approach and was approximately 752,000 miles (1.21 million km) from Vesta. The asteroid appears as a small, bright pearl against a background of stars. Vesta also is known as a protoplanet, because it is a large body that almost formed into a planet."After plying the seas of space for more than a billion miles, the Dawn team finally spotted its target," said Carol Raymond, Dawn's deputy principal investigator at NASA's Jet Propulsion Laboratory in Pasadena, California. "This first image hints of detailed portraits to come from Dawn's upcoming visit."Vesta is 330 miles (530 km) in diameter and the second most massive object in the asteroid belt. Ground- and space-based telescopes obtained images of the bright orb for about two centuries, but with little surface detail.Mission managers expect Vesta's gravity to capture Dawn in orbit on July 16. To enter orbit, Dawn must match the asteroid's path around the sun, which requires very precise knowledge of the body's location and speed. By analyzing where Vesta appears relative to stars in framing camera images, navigators will pin down its location and enable engineers to refine the spacecraft's trajectory.Dawn will start collecting science data in early August at an altitude of approximately 1,700 miles (2,700 km) above the asteroid's surface. As the spacecraft gets closer, it will snap multi-angle images allowing scientists to produce topographic maps. Dawn will later orbit at approximately 120 miles (200 km) to perform other measurements and obtain closer shots of parts of the surface. Dawn will remain in orbit around Vesta for one year. After another long cruise phase, Dawn will arrive in 2015 at its second destination, Ceres, an even more massive body in the asteroid belt.Gathering information about these two icons of the asteroid belt will help scientists unlock the secrets of our solar system's early history. The mission will compare and contrast the two giant asteroids shaped by different forces. Dawn's science instruments will measure surface composition, topography and texture. Dawn also will measure the tug of gravity from Vesta and Ceres to learn more about their internal structures. The spacecraft's full odyssey will take it on a 3-billion-mile (5-billion-km) journey, which began with its launch in September 2007.

WASHINGTON, April 5 (Xinhua) -- NASA and co-researchers from the United States, the Republic of Korea and Japan have found a new mineral named "Wassonite" in one of the most historically significant meteorites recovered in Antarctica in December 1969, the U.S. space agency said on Tuesday in a statement.The new mineral was discovered within the meteorite officially designated Yamato 691 enstatite chondrite. The meteorite likely may have originated from an asteroid orbiting between Mars and Jupiter. Wassonite is among the tiniest, yet most important, minerals identified in the 4.5-billion-year-old sample.The research team, headed by NASA space scientist Keiko Nakamura-Messenger, added the mineral to the list of 4,500 officially approved by the International Mineralogical Association."Wassonite is a mineral formed from only two elements, sulfur and titanium, yet it possesses a unique crystal structure that has not been previously observed in nature," said Nakamura-Messenger.In 1969, members of the Japanese Antarctic Research Expedition discovered nine meteorites on the blue ice field of the Yamato Mountains in Antarctica. This was the first significant recovery of Antarctic meteorites and represented samples of several different types.As a result, the United States and Japan conducted systematic follow-up searches for meteorites in Antarctica that recovered more than 40,000 specimens, including extremely rare Martian and lunar meteorites.Researchers found Wassonite surrounded by additional unknown minerals that are being investigated. The mineral is less than one-hundredth the width of a human hair or 50x450 nanometers. It would have been impossible to discover without NASA's transmission electron microscope, which is capable of isolating the Wassonite grains and determining their chemical composition and atomic structure."More secrets of the universe can be revealed from these specimens using 21st century nano-technology," said Nakamura- Messenger.The new mineral's name was approved by the International Mineralogical Association. It honors John T. Wasson, professor at the University of California, Los Angeles. Wasson is known for his achievements across a broad swath of meteorite and impact research, including the use of neutron activation data to classify meteorites and to formulate models for the chemical makeup of bulk chondrites.

WASHINGTON, March 4 (Xinhua) -- New data suggest that the epilepsy drug Topamax (topiramate) and its generic versions increase the risk for the birth defects cleft lip and cleft palate in babies born to women who use the medication during pregnancy, the U.S. Food and Drug Administration (FDA) said Friday in a statement.Before prescribing topiramate, approved to treat certain types of seizures in people who have epilepsy, health care professionals should warn patients of childbearing age about the potential hazard to the fetus if a woman becomes pregnant while using the drug, the FDA said.Topiramate also is approved to prevent migraine headaches, but not to relieve the pain of migraines."Health care professionals should carefully consider the benefits and risks of topiramate when prescribing it to women of childbearing age," said Russell Katz, director of the Division of Neurology Products in the FDA's Center for Drug Evaluation and Research. "Alternative medications that have a lower risk of birth defects should be considered."Cleft lip and cleft palate, collectively called oral clefts, are birth defects that occur when parts of the lip or palate do not completely fuse together early in the first trimester of pregnancy, a time when many women do not know they are pregnant.The defects range from a small notch in the lip to a groove that runs into the roof of the mouth and nose, possibly leading to problems with eating, talking, and to ear infections. Surgery often is performed to close the lip and palate and most children do well after treatment.Data from the North American Antiepileptic Drug (AED) Pregnancy Registry indicate an increased risk of oral clefts in infants exposed to topiramate during the first trimester of pregnancy. Infants exposed to topiramate as a single therapy experienced a 1.4 percent prevalence of oral clefts, compared with a prevalence of 0.38 percent - 0.55 percent in infants exposed to other antiepileptic drugs.Infants of mothers who did not have epilepsy and were not being treated with other antiepileptic drugs had a prevalence of 0.07 percent. Similar data from the United Kingdom Epilepsy and Pregnancy Register supported the North American AED Pregnancy Registry data.According to the FDA, before starting topiramate, pregnant women and women of childbearing potential should discuss other treatment options with their health care professional.

BEIJING, April 12 (Xinhuanet) -- The elderly have a difficult time with multi-tasking as a study suggests that older brains behave differently when it comes to switching between two tasks, according to media reports on Tuesday.Researchers used functional magnetic resonance imaging (FMRI) to analyze brain activity in 20 people over age 60 by asking them to contemplate outdoor photos shown briefly. Then the elderly were presented with the picture of a face and asked to determine its gender and age, before being asked to recall details from the original scene they viewed.Researchers then compared their results to a similar experiment with 20 younger adults and found the brains of older subjects were less capable of disengaging from the interruption and reestablishing the neural connections necessary to switch back to focusing on the original memory."Unlike younger individuals, older adults failed to both disengage from the interruption and re-establish functional connections associated with the disrupted memory network," write Wesley C. Clapp of the University of California, San Francisco, and colleagues in the Proceedings of the National Academy of Sciences.The study, published in the online edition of the journal Proceedings of the National Academy of Sciences, sheds new lights into a growing body of studies showing that one's ability to move from one task to another in quick succession becomes more difficult with age.

LOS ANGELES, April 14 (Xinhua) -- Vegetarians experience a much lower risk of metabolic syndrome than non-vegetarians, U.S. researchers have found.Researchers at Loma Linda University in California based their findings on analysis of more than 700 adults randomly sampled from a long-term study of the lifestyle and health of almost 100,000 Seventh-day Adventist Christians across the United States and Canada.While 25 percent of vegetarians had metabolic syndrome, the number significantly rises to 37 percent for semi-vegetarians and 39 percent for non-vegetarians, according to the study published in the April issue of the journal Diabetes Care.The findings showed that the risk of developing metabolic syndrome is 36 percent lower among vegetarians than non- vegetarians.This means that vegetarians are less likely to develop heart disease, diabetes and stroke -- three major conditions that are closely linked with metabolic syndrome, the researchers say.The study also found that vegetarians, though slightly older than non-vegetarians, had lower triglycerides, glucose levels, blood pressure, waist circumference, and body mass index (BMI). Semi-vegetarians, meanwhile, also had a significantly lower BMI and waist circumference compared to those who ate meat more regularly.The findings will not be affected by other factors such as age, gender, race, physical activity, calories consumed, smoking, and alcohol intake, the researchers say."In view of the high rate of metabolic syndrome in the United States and its deleterious health effects, we wanted to examine lifestyle patterns that could be effective in the prevention and possible treatment of this disorder," says lead researcher Nico S. Rizzo, PhD."I was not sure if there would be a significant difference between vegetarians and non-vegetarians, and I was surprised by just how much the numbers contrast," he says. "It indicates that lifestyle factors such as diet can be important in the prevention of metabolic syndrome."