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WASHINGTON, June 15 (Xinhua) -- Using the deepest X-ray image ever taken, astronomers found the first direct evidence that massive black holes were common in the early universe, the U.S. National Aeronautics and Space Administration (NASA) said Wednesday in a statement.The discovery from NASA's Chandra X-ray Observatory shows that very young black holes grew more aggressively than previously thought, in tandem with the growth of their host galaxies.By pointing Chandra at a patch of sky for more than six weeks, astronomers obtained what is known as the Chandra Deep Field South (CDFS). When combined with very deep optical and infrared images from NASA's Hubble Space Telescope, the new Chandra data allowed astronomers to search for black holes in 200 distant galaxies, from when the universe was between about 800 million to 950 million years old."Until now, we had no idea what the black holes in these early galaxies were doing, or if they even existed," said Ezequiel Treister of the University of Hawaii, lead author of the study to appear Thursday in journal Nature. "Now we know they are there, and they are growing like gangbusters."The super-sized growth means that the black holes in the CDFS are less extreme versions of quasars -- very luminous, rare objects powered by material falling onto supermassive black holes. However, the sources in the CDFS are about a hundred times fainter and the black holes are about a thousand times less massive than the ones in quasars.The observations found that between 30 and 100 percent of the distant galaxies contain growing supermassive black holes. Extrapolating these results from the small observed field to the full sky, there are at least 30 million supermassive black holes in the early universe. This is a factor of 10,000 larger than the estimated number of quasars in the early universe."It appears we've found a whole new population of baby black holes," said co-author Kevin Schawinski of Yale University. "We think these babies will grow by a factor of about a hundred or a thousand, eventually becoming like the giant black holes we see today almost 13 billion years later."

URUMQI, Sept. 5 (Xinhua) -- The first China-Eurasia Expo that concluded Monday in Urumqi, capital of northwest China's Xinjiang Uygur Autonomous Region, has clinched trade and technical cooperation contracts worth about 130 billion U.S. dollars, expo organizer said.Among all contracts, 5.5 billion dollars are clinched between Chinese and foreign companies, while 124 billion dollars are among Chinese companies, the organizer said.About 50,000 officials and business people from China and about 30 countries, regions and international organizations attended the trade fair, which also attracted an audience of more than 300,000 people.The event was upgraded from the 19-year-old China Urumqi Foreign Economic Relations and Trade Fair, a regional trade fair, last year.The fair covered an area of nearly 80,000 square meters for its more than 4,000 exhibition booths, according to the organizer.

WASHINGTON, Sept. 26 (Xinhua) -- Older people with low blood levels of vitamin B12 markers may be more likely to have lower brain volumes and have problems with their thinking skills, according to researchers at Rush University Medical Center in Chicago.The results of the study will be published Tuesday in Neurology, the medical journal of the American Academy of Neurology.Foods that come from animals, including fish, meat, especially liver, milk, eggs and poultry are usual sources of vitamin B12.The study involved 121 older residents of the south side of Chicago over the age of 65. They had blood drawn to measure levels of vitamin B12 and B12-related markers that can indicate a B12 deficiency. The same subjects took tests measuring their memory and other cognitive skills.An average of four-and-a-half years later, MRI scans of the participants' brains were taken to measure total brain volume and look for other signs of brain damage.Having high levels of four of five markers for vitamin B12 deficiency was associated with having lower scores on the cognitive tests and smaller total brain volume."Our findings definitely deserve further examination," said Christine Tangney, associate professor at Rush University Medical Center and lead author of the study. "It's too early to say whether increasing vitamin B12 levels in older people through diet or supplements could prevent these problems, but it is an interesting question to explore. Findings from a British trial with B vitamin supplementation are also supportive of these outcomes."On the cognitive tests, the scores ranged from -2.18 to 1.42, with an average of 0.23. For each increase of one micromole per liter of homocysteine -- one of the markers of B12 deficiency -- the cognitive scores decreased by 0.03 standardized units or points.Tangney noted that the level of vitamin B12 itself in the blood was not associated with cognitive problems or loss in brain volume. "Our findings lend support for the contention that poor vitamin B12 status is a potential risk factor for brain atrophy and may contribute to cognitive impairment," said Tangney.

WASHINGTON, Sept. 26 (Xinhua) -- Older people with low blood levels of vitamin B12 markers may be more likely to have lower brain volumes and have problems with their thinking skills, according to researchers at Rush University Medical Center in Chicago.The results of the study will be published Tuesday in Neurology, the medical journal of the American Academy of Neurology.Foods that come from animals, including fish, meat, especially liver, milk, eggs and poultry are usual sources of vitamin B12.The study involved 121 older residents of the south side of Chicago over the age of 65. They had blood drawn to measure levels of vitamin B12 and B12-related markers that can indicate a B12 deficiency. The same subjects took tests measuring their memory and other cognitive skills.An average of four-and-a-half years later, MRI scans of the participants' brains were taken to measure total brain volume and look for other signs of brain damage.Having high levels of four of five markers for vitamin B12 deficiency was associated with having lower scores on the cognitive tests and smaller total brain volume."Our findings definitely deserve further examination," said Christine Tangney, associate professor at Rush University Medical Center and lead author of the study. "It's too early to say whether increasing vitamin B12 levels in older people through diet or supplements could prevent these problems, but it is an interesting question to explore. Findings from a British trial with B vitamin supplementation are also supportive of these outcomes."On the cognitive tests, the scores ranged from -2.18 to 1.42, with an average of 0.23. For each increase of one micromole per liter of homocysteine -- one of the markers of B12 deficiency -- the cognitive scores decreased by 0.03 standardized units or points.Tangney noted that the level of vitamin B12 itself in the blood was not associated with cognitive problems or loss in brain volume. "Our findings lend support for the contention that poor vitamin B12 status is a potential risk factor for brain atrophy and may contribute to cognitive impairment," said Tangney.

WELLINGTON, Aug. 8 (Xinhua) -- A New Zealand study has found that people who work at least 50 hours a week can be up to three times more at risk of alcohol problems than people who work fewer hours.The study, conducted by the University of Otago, used data that followed more than 1,000 people born in Christchurch in 1977 through to age 30.Study leader Dr Sheree Gibb said it aimed to examine whether working hours were related to alcohol problems in early adulthood.Data from more than 1,000 participants at ages 25 and 30 showed a significant association between longer working hours and alcohol- related problems.Longer working hours were associated with higher levels of alcohol problems including frequent alcohol use and alcohol abuse or dependence.People who worked 50 hours or more on average a week were 1.8 to 3.3 times more likely to have alcohol-related problems than those who were not working, and about 1.2 to 1.5 times more likely to have alcohol-related problems than those who worked 30 to 49 hours a week.The higher risk of alcohol abuse for those who worked longer hours was evident in both men and women, according to the study.Gibb said the finding could suggest a need for consideration of policies and programs targeting individuals who worked long hours, with the aim of reducing rates of alcohol-related problems.The article had been accepted for publication by the UK-based journal Addiction.