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BEIJING, Sept. 2 (Xinhuanet) -- The amount of space junk orbiting the Earth could cause fatal leaks in spaceships or destroy valuable satellites, according to a report released by the U.S. National Research Council.Computer models have shown that the number of orbital debris "has reached a tipping point, with enough currently in orbit to continually collide and create even more debris, raising the risk of spacecraft failures," the Research Council said Thursday.So far, there are 22,000 pieces of debris large enough to track from the ground, but smaller objects could still cause serious damage.New international regulations are needed to limit space junk.And more researches should be done to test the possible use of launching magnetic nets or giant umbrellas to push the debris further towards the Earth where it would burn up, or into a higher but safer orbit.

CANBERRA, Sept. 9 (Xinhua) -- Australia on Friday launched the first national study to find out whether low to moderate levels of alcohol drank by pregnant women are harmful or not to an unborn child, hoping to provide a clear indication about the safe amount of alcohol for pregnant women.The Murdoch Children's Research Institute in Melbourne, which commissioned the study, is recruiting 2000 pregnant women who will be quizzed throughout their pregnancy about their drinking habits, general health and diets.Their babies will then undergo medical checks, when they turn one and again at two to see if their brains, development and behavior was affected by alcohol consumed by their mums.According to lead researcher associate professor, Jane Halliday, while there was solid evidence about the dangers of heavy drinking for an unborn baby, it was not known if there was a safe amount of alcohol pregnant women could drink.She said the study hoped to shed light on the best approach to alcohol use during pregnancy."The problem is that for about half of women that get pregnant it is unplanned, and a lot of women are drinking around the time they get pregnant and may drink for the first month or so and that creates a lot of anxiety," Assoc Prof Halliday said in a statement."From the few international and Australian studies there's conflicting evidence as to whether there's an adverse effect."We firmly believe that no drinking is the safest option, but our main aim is to provide an evidence base to the policy and answer questions about individual risks."The study came after research by the University of Newcastle published in 2010 revealed 80 percent of Australian women drank during pregnancy.

BEIJING, July 25 (Xinhuanet) -- Apple is planning a third, even larger Shanghai store, as well as dozens of other stores throughout China, to cope with huge crowds at its flagship store and a branch, according to media reports Monday.Apple says its Chinese outlets -- two in Beijing and two in Shanghai -- are the four most heavily trafficked Apple stores in the world. They also generate the most revenue. Apple’s push into China shows the depth of the country’s fast-growing economy, and shows that with products not so easy to counterfeit, Chinese consumers are willing to pay a premium.For the first three quarters of Apple’s fiscal year, revenue in China and its Taiwan, Hong Kong was 8.8 billion dollars -- six times that of a year earlier. China has become the second-largest market, after the United States, for apps that run on the smartphone and tablet, according to Distimo, a Dutch company that tracks the popularity of apps.In addition, Apple has been eager to team up with state-run telecom companies, which looks after mobile phone subscriptions.

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.

LOS ANGELES, June 17 (Xinhua) -- The size of low-oxygen zones created by respiring bacteria is extremely sensitive to changes in depth caused by oscillations in climate, thus posing a distant threat to marine life, a new study suggests."The growth of low-oxygen regions is cause for concern because of the detrimental effects on marine populations -- entire ecosystems can die off when marine life cannot escape the low- oxygen water," said lead researcher Curtis Deutsch, assistant professor of atmospheric and oceanic sciences at University of California, Los Angeles."There are widespread areas of the ocean where marine life has had to flee or develop very peculiar adaptations to survive in low- oxygen conditions," Deutsch said in the study to be published in an upcoming print edition of the journal Science.A team led byDeutsch used a specialized computer simulation to demonstrate for the first time that fluctuations in climate can drastically affect the habitability of marine ecosystems.The study also showed that in addition to consuming oxygen, marine bacteria are causing the depletion of nitrogen, an essential nutrient necessary for the survival of most types of algae."We found there is a mechanism that connects climate and its effect on oxygen to the removal of nitrogen from the ocean," Deutsch said. "Our climate acts to change the total amount of nutrients in the ocean over the timescale of decades."Low-oxygen zones are created by bacteria living in the deeper layers of the ocean that consume oxygen by feeding on dead algae that settle from the surface. Just as mountain climbers might feel adverse effects at high altitudes from a lack of air, marine animals that require oxygen to breathe find it difficult or impossible to live in these oxygen-depleted environments, Deutsch said.Sea surface temperatures vary over the course of decades through a climate pattern called the Pacific Decadal Oscillation, during which small changes in depth occur for existing low-oxygen regions, Deutsch said. Low-oxygen regions that rise to warmer, shallower waters expand as bacteria become more active; regions that sink to colder, deeper waters shrink as the bacteria become more sluggish, as if placed in a refrigerator."We have shown for the first time that these low-oxygen regions are intrinsically very sensitive to small changes in climate," Deutsch said in remarks published Friday by the American Association for the Advancement of Science on its website. "That is what makes the growth and shrinkage of these low-oxygen regions so dramatic."Molecular oxygen from the atmosphere dissolves in sea water at the surface and is transported to deeper levels by ocean circulation currents, where it is consumed by bacteria, Deutsch said."The oxygen consumed by bacteria within the deeper layers of the ocean is replaced by water circulating through the ocean," he said. "The water is constantly stirring itself up, allowing the deeper parts to occasionally take a breath from the atmosphere."A lack of oxygen is not the only thing fish and other marine life must contend with, according to Deutsch. When oxygen is very low, the bacteria will begin to consume nitrogen, one of the most important nutrients that sustain marine life."Almost all algae, the very base of the food chain, use nitrogen to stay alive," Deutsch said. "As these low-oxygen regions expand and contract, the amount of nutrients available to keep the algae alive at the surface of the ocean goes up and down. "Understanding the causes of oxygen and nitrogen depletion in the ocean is important for determining the effect on fisheries and fish populations, he said.

来源：资阳报