皮肤病 医院 阜阳阜阳灰指甲去那家医院,阜阳哪家医院看痤疮的效果比较好,阜阳正规医院治疗灰指甲要多少钱,阜阳市那家医院治疗花斑癣好,阜阳哪里的毛囊炎医院好,阜阳白斑中医医院,阜阳可以治疗痤疮的医院

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.

JIUQUAN, Gansu, Aug. 18 (Xinhua) -- China's experimental orbiter SJ-11-04, which was launched by a Long March II-C rocket Thursday, failed to enter the designated orbit due to a malfunction of the rocket.The rocket experienced malfunction during the flight following its launch from Jiuquan Satellite Launch Center at 5:28 p.m. Beijing Time in northwest Gansu Province.The specific cause of the failure is being analyzed.

BEIJING, Aug. 22 (Xinhuanet) -- Researchers have discovered how a human egg captures an incoming sperm for fertilization, paving the way to help couples suffering from infertility, according to media reports on Monday.An international team of researchers found that a sugar chain known as the sialyl-lewis-x sequence (SLeX) makes the outer coat of the egg “sticky,” which has proven to be helpful in binding the egg and the sperm.As a result, this observation has filled in a huge gap in the understanding of fertility and provides hope for ultimately helping couples who currently cannot conceive.Scientists and doctors know that a sperm identifies an egg when proteins on the head of the sperm match and bind to a series of specific sugars in the egg’s outer coating. With a successful match of proteins, the outside surfaces of the sperm and egg then bind together before merging, which is then followed by delivery of sperm’s DNA into egg.To identify this molecules, the researchers used ultra-sensitive mass-spectrometric imaging technology to observe and identify which molecules are most likely to be key in the binding process.They experimented with a range of synthesised sugars in the laboratory and found that it is SLeX that specifically binds sperm to an egg.According to the World Health Organisation, infertility affects about 15 percent of reproductive-aged couples around the world and almost one in every seven couples in Britain has problems conceiving a child for various reasons.

WASHINGTON, July 20 (Xinhua) -- The loss of a protein that coats sperm may explain a significant proportion of infertility in men worldwide, according to a study by an international team of researchers led by University of California Davis.A paper describing the work was published Wednesday in the journal Science Translational Medicine. The research could open up new ways to screen and treat couples for infertility.The gene DEFB126 encodes a protein called Beta Defensin 126, which coats the surface of sperm and helps it penetrate cervical mucus in the female. A survey of samples from the U.S., Britain and China showed that as many as a quarter of men worldwide carry two copies of the defective gene.In the new study, researchers found that men with a muted DEFB126 lack Beta Defensin 126, making it much more difficult for sperm to swim through the mucus and eventually join with an egg.Examining 500 newly married Chinese couples, researchers found that the lack of Beta Defensin 126 in men with the DEFB126 mutation lowered fertility (even among men that did not display other deficiencies usually associated with infertility, like inadequate semen volume and low sperm motility). Wives of men with the Beta Defensin 126 variant were significantly less likely to become pregnant than were other couples, and 30 percent less likely to have a birth.This genetic variation in DEFB126 likely accounts for many unexplained cases of infertility, researchers say. They hope next to work with a major infertility program in the U.S. to further explore the role of the mutation.

BEIJING, Sept. 9 (Xinhua) -- Lenovo Group, China's largest PC maker, said it aims to become the world's second-largest PC provider by the end of this year, China Daily reported Friday.The PC maker will take aggressive action to expand in the international PC market left by its competitors because of strategy adjustment, the English newspaper quoted Liu Chuanzhi, the board chairman of Lenovo, as saying.A few weeks ago, the world's biggest PC maker Hewlett-Packard Corp. said it will spin off its PC sector. Apple Inc's former CEO Steve Jobs resigned."The Chinese market is the starting point for Lenovo, but it won't be the only place Lenovo should put emphasis on. We will set up a more active strategy for expanding in overseas markets," Liu said.The PC maker has long been focusing on the global market. It purchased the PC division of the IBM Corp. a few years ago. In January, it announced a 175-million-U.S.-dollar joint venture with Japan's NEC Corp. In July, Lenovo completed its acquisition of Medion AG, a German multimedia and consumer electronics maker.