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NEW YORK, Aug. 19 (Xinhua) -- U.S. crude oil price edged down on Friday, ending the week with a 3.65-percent loss, the fourth straight drop in the week.With absence of major macro-economic news, crude prices on Friday mainly followed the dollar's steps. As the dollar dipped to its historic low against the Japanese yen while dropping also against the euro, oil rallied for most of the trading session.But in the last trading hour, crude turned negative because the dollar bounced back from low and the U.S. stocks turned to red. The dollar index, tracking the greenback's performance against a basket of currencies, fell 0.4 percent.Crude prices fell sharply on Thursday as fears of a double-dip recession triggered sell-off of riskier assets. WTI dropped nearly 6 percent. On Friday, the markets seemed to start calming down. But for the week, it still posted a fall of 3.65 percent.Light, sweet crude for September delivery fell moderately 12 cents, or 0.15 percent to settle at 82.26 dollars a barrel on the New York Mercantile Exchange after trading from 79.17 to 83.55 dollars.But in London, Brent crude for October delivery gained 1.63 dollars, or 1.52 percent to close at 108.62 dollars a barrel. For this week, it gained 59 cents, or 0.55 percent.

WASHINGTON, Sept. 14 (Xinhua) -- Controlling diabetes may someday involve mining stem cells from the lining of the uterus, Yale School of Medicine researchers report in a new study published Wednesday in the journal Molecular Therapy. The team treated diabetes in mice by converting cells from the uterine lining into insulin-producing cells.The endometrium or uterine lining, is a source of adult stem cells. These cells generate uterine tissue each month as part of the menstrual cycle. Like other stem cells, however, they can divide to form other kinds of cells.Led by Yale Professor Hugh Taylor, the researchers bathed endometrial stem cells in cultures containing special nutrients and growth factors. Responding to these substances, the endometrial stem cells adopted the characteristics of beta cells in the pancreas that produce insulin. Over the course of a three- week incubation process, the endometrial stem cells took on the shape of beta cells and began to make proteins typically made by beta cells. Some of these cells also produced insulin.After a meal, the body breaks food down into components like the sugar glucose, which then circulates in the blood. In response, beta cells release insulin, which allows the body's cells to take in the circulating glucose. In this study, Taylor and his team exposed the mature stem cells to glucose and found that, like typical beta cells, the cultured cells responded by producing insulin. The team then injected diabetic mice with the mature, insulin-making stem cells. The mice had few working beta cells and very high levels of blood glucose.Mice that did not receive the stem cell therapy continued having high blood sugar levels, developed cataracts and were lethargic. In contrast, mice that received the cell therapy were active and did not develop cataracts, but the animals' blood sugar levels remained higher than normal.The Yale team's findings suggest that endometrial stem cells could be used to develop insulin-producing islet cells, which are found in the pancreas. These islet cells could then be used to advance the study of islet cell transplantation to treat people with diabetes.Taylor said in a statement that the next step in the research will be to verify how long this treatment remains effective.

WASHINGTON, July 15 (Xinhua) -- Researchers at Mount Sinai School of Medicine have found that grape seed polyphenols -- a natural antioxidant -- may help prevent the development or delay the progression of Alzheimer's disease.The research, led by Giulio Pasinetti, was published online Friday in the Journal of Alzheimer's Disease, which causes brain changes that gradually get worse.This is the first study to evaluate the ability of grape- derived polyphenols to prevent the generation of a specific form of amyloid (A) peptide, a substance in the brain long known to cause the neurotoxicity associated with Alzheimer's disease.In partnership with a team at the University of Minnesota, Pasinetti and collaborators administered grape seed polyphenolic extracts to mice genetically determined to develop memory deficits and A neurotoxins similar to those found in Alzheimer's disease. They found that the brain content of the A*56, a specific form of A previously implicated in the promotion of Alzheimer's disease memory loss, was substantially reduced after treatment.Previous studies suggest that increased consumption of grape- derived polyphenols, whose content, for example, is very high in red wine, may protect against cognitive decline in Alzheimer's. This new finding corroborates those theories."Since naturally occurring polyphenols are also generally commercially available as nutritional supplements and have negligible adverse events even after prolonged periods of treatment, this new finding holds significant promise as a preventive method or treatment, and is being tested in translational studies in Alzheimer's disease patients," said Pasinetti.In Alzheimer's disease, brain cells degenerate and die, causing a steady decline in memory and mental function.

BEIJING, Sept. 25 (Xinhua) -- As China's economy has soared to the second place in the world, the country's scientific strength has also surged -- if only measured by the numbers.Chinese researchers published more than 1.2 million papers from 2006 to 2010 -- second only to the United States but well ahead of Britain, Germany and Japan, according to data recently published by Elsevier, a leading international scientific publisher and data provider. This figure represents a 14 percent increase over the period from 2005 to 2009.The number of published academic papers in science and technology is often seen as a gauge of national scientific prowess.But these impressive numbers mask an uncomfortable fact: most of these papers are of low quality or have little impact. Citation per article (CPA) measures the quality and impact of papers. China's CPA is 1.47, the lowest figure among the top 20 publishing countries, according to Elsevier's Scopus citation database.China's CPA dropped from 1.72 for the period from 2005 to 2009, and is now below emerging countries such as India and Brazil. Among papers lead-authored by Chinese researchers, most citations were by domestic peers and, in many cases, were self-citations."While quantity is an important indicator because it gives a sense of scientific capacity and the overall level of scientific activity in any particular field, citations are the primary indicator of overall scientific impact," said Daniel Calto, Director of SciVal Solutions at Elsevier North America.Calto attributed China's low CPA to a "dilution effect.""When the rise in the number of publications is so rapid, as it has been in China -- increasing quantity does not necessarily imply an overall increase in quality," said Calto.He noted the same pattern in a variety of rapidly emerging research countries such as India, Brazil, and earlier in places like the Republic of Korea."Chinese researchers are too obsessed with SCI (Science Citation Index), churning out too many articles of low quality," said Mu Rongping, Director-General of the Institute of Policy and Management at the Chinese Academy of Sciences, China's major think tank.SCI is one of the databases used by Chinese researchers to look-up their citation performance. The alternative, Scopus, provides a wider coverage worldwide."Chinese researchers from a wide range of areas and institutions are vying for publication, as it is a key criterion for academic appraisal in China, if not the only one. As a result, the growth of quality pales in comparison to that of quantity," said Mu, an expert on China's national science policy and competitiveness.On the other hand, China also falls behind the United States in multidisciplinary research, which is a core engine for scientific advance and research excellence.From 2006 to 2010, China published 1,229,706 papers while the United States churned out 2,082,733. According to a new metric introduced by Elsevier's Spotlight research assessment solution, China generated 885 competencies while the United States had 1,817.In other words, China's total research output is more than half that of the United States, while the number of competencies showing China's strength in multidisciplinary research is less than half that of the United States.Cong Cao, an expert on China's science and technology, put it more bluntly in an article he wrote: "When the paper bubble bursts, which will happen sooner or later, one may find that the real situation of scientific research in China probably is not that rosy."China has been investing heavily in scientific research and technological development in recent years to strengthen its innovative capacity, The proportion of GDP spent on R&D grew from 0.9 percent in 2000 to 1.4 percent in 2007, according to the World Bank.An IMF forecast in 2010 says China now ranks second globally in R&D spending. The IMF calculates China's R&D expenditure at 150 billion U.S. dollars when based on Purchasing Power Parity, a widely used economic concept that attempts to equalize differences in standard of living among countries.By this measure, China surpassed Japan in R&D spending in 2010.Many see China's huge investment in R&D as the momentum behind the country's explosive increase in research papers."Getting published is, in some ways, an improvement over being unable to get published," Mu said. "But the problem is, if the papers continue to be of low quality for a long time, it will be a waste of resources."In China, academic papers play a central role in the academic appraisal system, which is closely related to degrees and job promotions.While acknowledging the importance of academic papers in research, Mu believes a more balanced appraisal system should be adopted. "This is a problem with science management. If we put too much focus on the quantity of research papers, we leave the job of appraisal to journal editors."In China, the avid pursuit of publishing sometimes gives rise to scientific fraud. In the most high-profile case in recent years, two lecturers from central China's Jinggangshan University were sacked in 2010 after a journal that published their work admitted 70 papers they wrote over two years had been falsified."This is one of the worst cases. These unethical people not only deceived people to further their academic reputations, they also led academic research on the wrong path, which is a waste of resources," Mu said.A study done by researchers at Wuhan University in 2010 says more than 100 million U.S. dollars changes hands in China every year for ghost-written academic papers. The market in buying and selling scientific papers has grown five-fold in the past three years.The study says Chinese academics and students often buy and sell scientific papers to swell publication lists and many of the purported authors never write the papers they sign. Some master's or doctoral students are making a living by churning out papers for others. Others mass-produce scientific papers in order to get monetary rewards from their institutions.A 2009 survey by the China Association for Science and Technology (CAST) of 30,078 people doing science-related work shows that nearly one-third of respondents attributed fraud to the current system that evaluates researchers' academic performance largely on the basis of how many papers they write and publish.Despite rampant fraud, China will continue to inject huge money into science. According to the latest national science guideline, which was issued in 2006 by the State Council, the investment in R&D will account for 2.5 percent of GDP in 2020."If China achieves its stated goal of investing 2.5 percent of its GDP in R&D in 2020, and sustains its very fast economic growth over the next decade, it would quite likely pass the U.S. in terms of total R&D investment sometime in the late 2010s," said Calto, adding that it is also quite likely that at some point China will churn out more papers than the United States.According to Calto, China does mostly applied research, which helps drive manufacturing and economic growth, while basic research only accounts for 6 percent, compared with about 35 percent in Germany, Britain, and the United States, and 16 percent in Japan."In the long term, in order to really achieve dominance in any scientific area, I think it will be necessary to put significant financial resources into fundamental basic research -- these are the theoretical areas that can drive the highest level of innovation," Calto said.

来源：资阳报