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SAN FRANCISCO, July 15 (Xinhua) -- U.S. microblogging platform Twitter on Friday marked its fifth anniversary since public debut."Twitter, then called Twttr, opened to the public five years ago today," the company said in a Tweet, a short message within 140 characters users are allowed to communicate on the website."Twttr is a new mobile service that helps groups of friends bounce random thoughts around with SMS," co-founder Biz Stone described the service in a blog post on July 13, 2006, two days before its public debut."There were 224 Tweets sent on July 15, 2006. Today, users send that many Tweets in less than a tenth of a second," said the San Francisco-based company.Twitter said more than 600,000 new users signed up on Thursday while it took it more than 16 months to reach the first 600,000 Twitter accounts.The tipping point for the service's popularity was the 2007 South by Southwest festival, a set of film, interactive and music festivals and conferences that take place every March in Austin, Texas. During the event, the Tweets sent per day grew from 20,000 to 60,000.With an estimated user base of 200 million worldwide, some 200 million Tweets are generated and 1.6 billion search queries are handled every day, the company said.According to research firm EMarketer, advertising sales on Twitter is expected to reach 150 million U.S. dollars this year. SharesPost, a secondary market for privately held companies, has assessed Twitter's current worth at 6.8 billion dollars.

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.

BEIJING, Aug. 24 (Xinhua) -- China will prioritize the development of six types of new materials in its new material industry over the next five years, the China Securities Journal said on Wednesday.The report cited an insider, who noted that the country's 12th Five-Year Plan (2011-2015) for the new material industry will come out in September, in which the government will launch key projects to support the development of the six materials.The six materials will be high-strength light alloy, advanced iron and steel, carbon fiber composite, new power battery material, function coated material, and rare earth function material, according to the report.The plan states each of the six sub industries will form a sizable industrial scale, with the industry's total output value to hit trillions of yuan by the end of 2015, and the self-supply rate to reach 70 percent during the period, the report said.Meanwhile, the government will also foster the development of materials in sectors such as green building material and the biomedical industry over the next five years, it added.

WASHINGTON, Sept. 13 (Xinhua) -- The U.S. Department of Health and Human Services (HHS), with several partners, on Tuesday launched Million Hearts, an initiative that aims to prevent one million heart attacks and strokes over the next five years.The program will focus on helping Americans make healthy choices, such as preventing tobacco use and lowering consumption of salt and trans fats, and increasing use of treatments like aspirin and blood pressure and cholesterol-lowering medications.The HHS hopes that by 2017, 65 percent of high-risk patients will be taking aspirin and have their blood pressure and cholesterol under control. Currently, only 47 percent of high-risk patients take aspirin, and only 33 percent have their cholesterol and 46 percent their blood pressure under control.They also aim to cut smoking to 17 percent of Americans from 19 percent by 2017, and seek a 20 percent drop in sodium intake and a 50 percent drop in trans fat consumption."Heart disease causes one of every three American deaths and constitutes 17-percent of overall national health spending," said HHS Secretary Kathleen Sebelius in a statement. "By enlisting partners from across the health sector, Million Hearts will create a national focus on combating heart disease."

来源：资阳报