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WELLINGTON, July 29 (Xinhua) -- Scientists from around the world will gather on the east coast of New Zealand next week to discuss proposals to study "silent" earthquakes by drilling into the seabed.Silent quakes, also known as slow slip events, occur on the boundaries of the earth's tectonic plates, where one plate dives under another in areas known as subduction zones, and are slower than normal quakes, taking weeks or months to occur rather than seconds, and are rarely felt on the surface.About 70 scientists from 10 countries will convene in the city of Gisborne, which lies near the site of a major fault line and where scientists first identified silent earthquakes in 2002.Slow-slip events were first discovered with the advent of new measurement technologies on the west coast of Canada about 15 years ago and have since been recorded at about a dozen locations around the world, including four sites around New Zealand, said a spokesperson for New Zealand's Institute of Geological and Nuclear Sciences (GNS Science).About eight slow-slip episodes have occurred under Gisborne since 2002 at roughly two-year intervals.Scientists have proposed numerous theories to explain the phenomenon, but testing the theories is difficult as silent quakes happen many kilometers below ground."The best way to understand the true cause of slow-slip events is to drill into and sample the area on the plate boundary fault where they are known to occur, and monitor a whole range of physical and chemical properties at the plate interface," said Laura Wallace, of GNS Science.

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.

BEIJING, Sept. 23 (Xinhua) -- A defunct U.S. satellite is expected to crash down to Earth Friday, with nobody knowing where or when exactly it will hit. This was avoidable, a Chinese expert said Thursday.Pang Zhihao, a researcher from the Chinese Research Institute of Space Technology, told Xinhua that the crash could have been avoided had the satellite been put into a higher orbit, or manipulated to drop in the South Pacific when it had abundant fuel. It would pose no threat to Earth if these measures had been taken.NASA's tumbling, 5,900 kg Upper Atmosphere Research Satellite, or UARS, is the first of such man-made space vehicles that have been launched into outer space according to the agency's Mission to Planet Earth. The mission was launched in the 1990s.The mission is designed to provide data for better understanding Earth's upper atmosphere and the effects of natural and human interactions on the atmosphere.The satellite was deactivated in 2005 as it ran out of fuel and was left orbiting Earth like a big piece of space junk.There are other cases of defunct satellites. The European Space Agency said earlier its observation satellite ERS-2 has run out of fuel and is deorbiting. It would therefore also crash sooner or later.Pang said all countries which are operating space vehicles should take care of their own spacecrafts so that they won't pose any danger.The expert also said that the public need not worry too much.Pang said most spacecrafts will be incinerated upon re-entering Earth's atmosphere, and the debris will mostly likely fall into the ocean or hit an uninhabited area. In addition, a debris tracker is able to give a comparatively accurate prediction where the craft will fall about two hours before it hits Earth, giving residents, if there are any, time to evacuate.He added that there are several ways to minimize the threat of decommissioned spacecrafts, like putting them into higher orbits and crashing them into designated waters.Scientific progress would possibly bring about more ways of dealing with tumbling satellites. Scientists have already been trying to build spacecrafts with degradable materials so that they can self-destruct when re-entering Earth's atmosphere.

MOSCOW, Aug. 30 (Xinhua) -- Russia's space agency said Tuesday that a Proton-M rocket launch failed earlier this month because of a malfunction in the upper stage.The conclusion was reached by an independent investigation commission following a series of checks, Roscosmos said in a report that was posted on its website."The commission reported that the time span reserved for the gyrostabilized platform's turn was miscalculated and narrowed, which caused the Briz-M upper stage's disorientation and the satellite's journey to a wrong orbit," the agency said.Other systems in the upper stage performed well, the agency said, adding it has lifted a ban on launches of the Proton-M carrier rockets equipped with the Briz-M upper stage.Local media reported the Briz-M, manufactured by the Khrunichev State Research and Production Space Center, has had five failures over its 12-year history of operation.On Aug. 18, a Proton-M carrier rocket failed to deliver a communications satellite into orbit. After the failure, Russia suspended launches of Proton-M rockets pending the outcome of an investigation into the failure.

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.

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