和田男人勃起障碍的治疗(和田一般怀孕几天能用验孕棒测出来) (今日更新中)

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.

LOS ANGELES, June 3 (Xinhua) -- Eating earth may protect the stomach against toxins, parasites and pathogens, a new study suggests.To examine the possible benefits from eating earth, researchers at Cornell University analyzed reports from missionaries, plantation doctors, explorers, and anthropologists to put together a database of more than 480 cultural accounts of geophagy -- the eating of earth.The database includes as many details as possible about the circumstances under which earth was consumed, and by whom. The researchers could then use patterns in the data to evaluate each potential explanation.Studies in the database indicate that geophagy is common even when food is plentiful. Moreover, when people eat dirt they tend to eat only small quantities that are unlikely to fill an empty stomach.The database shows that geophagy is documented most commonly in women in the early stages of pregnancy and in pre-adolescent children. Both categories of people are especially sensitive to parasites and pathogens, according to the researchers.In addition, geophagy is most common in tropical climates where foodborne microbes are abundant. Finally, the database shows that people often eat earth during episodes of gastrointestinal stress.It's unlikely the intestinal problems are caused by the dirt itself because the type of clay people usually eat comes from deep in the ground, where pathogens and parasites are unlikely to contaminate it. Plus, people usually boil the clay before eating it.More study would be helpful to confirm the protection hypothesis, the researchers say, but the available data at this point clearly support it over the other explanations for eating earth."We hope this paper stimulates (more) research," said Sera Young, a researcher at Cornell University and the study's lead author. "More importantly, we hope readers agree that it is time to stop regarding geophagy as a bizarre, non-adaptive gustatory mistake.""With these data, it is clear that geophagy is a widespread behavior in humans ...that occurs during both vulnerable life stages and when facing ecological conditions that require protection."The study is appearing in the June issue of The Quarterly Review of Biology.

BEIJING, May 30 (Xinhuanet) -- Chronic diseases, including heart disease, stroke, cancer, chronic respiratory diseases and diabetes, are the leading cause of mortality in China, representing 85 percent of all deaths, said a senior health official.Kong Lingzhi, deputy director of the disease prevention and control bureau under the Ministry of Health, made the remarks on Saturday at the Forum of Prevention and Control of Chronic Disease."China is facing a great challenge from chronic diseases, which has a serious impact on both the economy and society," said Kong.Each year, about 3.7 million people die before they reach 60 because of chronic diseases. There are currently 200 million hypertension patients and 90 million diabetics in China, official statistics show.To address the challenge, "the government is now drafting an inter-ministerial roadmap for chronic disease intervention, which will set targets, define responsibilities and distribute guidelines for the prevention and control of chronic diseases," she said.The initiative aims to strengthen national and global monitoring and surveillance; scale up the implementation of evidence-based measures to reduce risk factors, such as tobacco use, an unhealthy diet, physical inactivity and harmful alcohol use; and improve access to cost-effective healthcare to prevent complications, disabilities and premature death.But more importantly, the roadmap will help gain attention and support for preventing and controlling chronic diseases and place it high on government working agendas, Kong explained.The government has focused more on addressing instant health crises up to now and policy and funding support for chronic disease control and prevention was very limited, admitted Mao Qun'an, spokesman of the ministry.Given that chronic disease control requires a systematic approach, tasks such as public health education, training for medical workers (especially the grassroots ones) and policies encouraging doctors' involvement need to be carried out, he said.The ultimate goal is to prevent people from getting ill rather than treating diseases, he added.Lei Zhenglong, deputy director of the disease prevention and control bureau, said that to enhance the capacity of medical workers was now the top priority for the initiative.At present, effective disease prevention work usually contradicts the financial interests of clinical doctors, analysts said.A respiratory disease doctor surnamed He with the Peking University People's Hospital said that he came under pressure from the hospital authorities when the number of inpatients declined due to his efforts to inform his patients about chronic disease prevention.

BEIJING, Aug. 23 (Xinhuanet) -- More than 90 percent of U.S. heart attack patients who need the lifesaving procedure receive it within just 90 minutes of being admitted to the hospital, according to a study released Monday in the journal Circulation.The study on the American Heart Association's journal shows that in 2010, 91 percent of heart attack patients who needed angioplasty were treated within the 90-minute window. While in 2005, 44% were.Researchers analyzed data on more than 300,000 such patients who underwent emergency angioplasty between January of 2005 and October of 2010.The improvement is the result of a nationwide effort between federal agencies, health care organizations and health care providers to improve heart attack care and outcome, said study author Dr. Harlan M. Krumholz, a professor of medicine and epidemiology and public health at Yale University School of Medicine, according to U.S. News reports.

WASHINGTON, June 9 (Xinhua) -- Observations from NASA's Voyager spacecraft suggest the edge of our solar system may not be smooth, but filled with a turbulent sea of magnetic bubbles, the U.S. space agency said Thursday in a statement.While using a new computer model to analyze Voyager data, scientists found the sun's distant magnetic field is made up of bubbles approximately 100 million miles wide. The bubbles are created when magnetic field lines reorganize. The new model suggests the field lines are broken up into self-contained structures disconnected from the solar magnetic field. The findings are described Thursday in the Astrophysical Journal.Like Earth, our sun has a magnetic field with a north pole and a south pole. The field lines are stretched outward by the solar wind or a stream of charged particles emanating from the star that interacts with material expelled from others in our corner of the Milky Way galaxy.The Voyager spacecraft, more than nine billion miles away from Earth, are traveling in a boundary region. In that area, the solar wind and magnetic field are affected by material expelled from other stars in our corner of the Milky Way galaxy."The sun's magnetic field extends all the way to the edge of the solar system," said astronomer Merav Opher of Boston University. "Because the sun spins, its magnetic field becomes twisted and wrinkled, a bit like a ballerina's skirt. Far, far away from the sun, where the Voyagers are, the folds of the skirt bunch up."Understanding the structure of the sun's magnetic field will allow scientists to explain how galactic cosmic rays enter our solar system and help define how the star interacts with the rest of the galaxy.So far, much of the evidence for the existence of the bubbles originates from an instrument aboard the spacecraft that measures energetic particles. Investigators are studying more information and hoping to find signatures of the bubbles in the Voyager magnetic field data."We are still trying to wrap our minds around the implications of the findings," said University of Maryland physicist Jim Drake, one of Opher's colleagues.Launched in 1977, the Voyager twin spacecraft have been on a 33- year journey. They are en route to reach the edge of interstellar space. NASA's Jet Propulsion Laboratory built the spacecraft and continues to operate them.

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