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WASHINGTON, Nov. 10 (Xinhua) -- Using its near-infrared vision to peer nine billion years back in time, NASA's Hubble Space Telescope has uncovered an extraordinary population of young dwarf galaxies brimming with star formation, the U.S. space agency announced on Thursday.While dwarf galaxies represent the most common type of galaxy in the universe, the rapid star-birth observed in these newly- found examples may force astronomers to reassess their understanding of the ways in which galaxies form.The galaxies are a hundred times less massive, on average, than the Milky Way, yet they churn out stars at such a furious pace that their stellar content would double in just 10 million years. By comparison, the Milky Way would take a thousand times longer to double its star population.The universe is estimated to be 13.7 billion years old, and these newly-discovered galaxies are extreme even for the young universe -- when most galaxies were forming stars at higher rates than they are today. Astronomers using Hubble's instruments could spot the galaxies because the radiation from young, hot stars has caused the oxygen in the gas surrounding them to light up like a bright neon sign."The galaxies have been there all along, but up until recently astronomers have been able only to survey tiny patches of sky at the sensitivities necessary to detect them," said Arjen van der Wel of the Max Planck Institute for Astronomy in Germany, lead author of a paper on the results to be published online on Nov. 14 in The Astrophysical Journal. "We weren't looking specifically for these galaxies, but they stood out because of their unusual colors. "The observations were part of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS), an ambitious three- year study to analyze the most distant galaxies in the universe. CANDELS is the first census of dwarf galaxies at such an early epoch."In addition to the images, Hubble has captured spectra that show us the oxygen in a handful of galaxies and confirmed their extreme star-forming nature," said co-author Amber Straughn at NASA's Goddard Space Flight Center. "Spectra are like fingerprints. They tell us the galaxies' chemical composition."The CANDELS team uncovered the 69 young dwarf galaxies in near- infrared images taken with Hubble's Wide Field Camera 3 and Advanced Camera for Surveys.The observations suggest that the newly-discovered galaxies were very common nine billion years ago. However, it is a mystery why the newly-found dwarf galaxies were making batches of stars at such a high rate.

WASHINGTON, Nov. 7 (Xinhua) -- U.S. researchers have demonstrated for the first time that the brain is a key player in regulating glucose (sugar) metabolism in humans.The findings, published Monday in the online edition of the Journal of Clinical Investigation, suggest that drugs targeting the brain and central nervous system could be a novel approach to treating diabetes."The brain is the body's only organ that needs a constant supply of glucose to survive, so it makes sense that it would have some say over how much glucose is produced," said study leader Meredith Hawkins, professor of medicine and director of the Global Diabetes Initiative at Yeshiva University, in a statement. "This role for the brain was demonstrated in earlier studies in rodents, but there was considerable controversy over whether the results could be applied to humans. We hope this study helps to settle the matter."In an earlier study in rodents, researchers showed that activation of potassium channels in the brain's hypothalamus sends signals to the liver that dampen its production of glucose. Those findings, published in Nature in 2005, challenged the conventional thinking that blood sugar production by the liver (the body's glucose factory) is regulated only by the pancreas (which makes insulin to metabolize glucose). But carefully performed studies on dogs, conducted at Vanderbilt University, failed to replicate the results, suggesting the Einstein findings in rodents might not be relevant to higher mammals, including humans.The current study, involving people, was aimed at resolving this controversy. Ten nondiabetic subjects were given oral diazoxide, a drug that activates potassium channels in the hypothalamus. (The drug is not used to treat diabetes.) Hormone secretion by the pancreas was controlled to ensure that any change in sugar production would only have occurred through the drug's effect on the brain. After the researchers administered the drug, blood tests revealed that patients' livers were producing significantly less glucose than before.Hawkins and her team then repeated this in rats, again giving diazoxide orally, achieving similar results. They confirmed that sufficient amounts of diazoxide crossed the blood-brain barrier to affect potassium channels in the hypothalamus. Additional experiments confirmed that diazoxide was working through the brain. Specifically, the researchers were able to completely block the effects of diazoxide by infusing a specific potassium channel blocker directly into the brain."This study confirms that the brain plays a significant role in regulating glucose production by the liver," said lead author Preeti Kishore, assistant professor of medicine. "We are now investigating whether this 'brain-to-liver' pathway is impaired in people with diabetes. If so, we may be able to restore normal glucose regulation by targeting potassium channels in the brain."

WASHINGTON, Dec. 5 (Xinhua) -- A recent study found that low vitamin D levels are significantly more prevalent in obese children and are associated with risk factors for type 2 diabetes. This study was accepted for publication in The Endocrine Society's Journal of Clinical Endocrinology & Metabolism.High rates of vitamin D deficiency have been found in obese populations and past studies have linked low vitamin D levels to cardiovascular disease and type 2 diabetes. But the mechanisms by which obesity and its comorbidities are related to vitamin D deficiency are not fully known.This new study examined associations between vitamin D levels and dietary habits in obese children, and tested whether there were correlations between vitamin D levels and markers of abnormal glucose metabolism and blood pressure.In this study, researchers measured vitamin D levels, blood sugar levels, serum insulin, body mass index (BMI) and blood pressure in 411 obese subjects and 87 control non-overweight subjects. Study participants were also asked to provide dietary information including daily intake of soda, juice and milk, average daily fruit and vegetable intake, and whether or not they routinely skipped breakfast. BMI is a measurement of body fat calculated from weight and height."Our study found that obese children with lower vitamin D levels had higher degrees of insulin resistance," said Micah Olson, of The University of Texas Southwestern Medical Center in Dallas and lead author of the study. "Although our study cannot prove causation, it does suggest that low vitamin D levels may play a role in the development of type 2 diabetes.""Poor dietary habits such as skipping breakfast and increased soda and juice intake were associated with the lower vitamin D levels seen in obese children," said Olson. "Future studies are needed to determine the clinical significance of lower vitamin D levels in obese children ... and whether treatment with vitamin D can improve primary clinical endpoints such as insulin resistance. "

NANJING, Dec. 8 (Xinhua) -- Chinese stargazers will have their best view of a total lunar eclipse in 10 years on Saturday if weather permits, the Zijinshan Astronomical Observatory under the Chinese Academy of Sciences (CAS) said Thursday.Wang Sichao, a research fellow with the observatory, said during the total eclipse, the full moon will not completely disappear from the Earth's shadow, but will take on a brilliant bronze color.He said the eclipse will be the best one seen in China since the last one occurred on Jan. 10, 2001."Theoretically, viewers can observe the eclipse from nearly everywhere in the country on Saturday," said the astronomer.He said the eclipse, the second this year, will last for 51 minutes. It will start at 8:45 p.m. and reach its climax at 10:06 p.m.Wang said Chinese viewers will have to wait until Oct. 8, 2014 to see the next total lunar eclipse.

来源：资阳报