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BEIJING, June 3 (Xinhua) -- Google lacked evidence to support its accusations that Chinese hackers are behind the alleged cyber attacks on hundreds of its email accounts and the timing to make such accusations is evil-intentioned, Chinese experts said on Friday."Google's accusation is neither serious nor credible as it has not published any evidence that shows the hackers are from China," said Dai Yiqi, a cyber security expert with Tsinghua University.Eric Grosse, engineering director of Google's Security Team wrote on the company blog Wednesday that unidentified hacker attacks likely originated from the eastern Chinese city of Jinan, tried to collect user passwords of the Gmail accounts of hundreds of users, including senior U.S. government officials, Chinese "human rights activists" and journalists.A report released in 2009 by the United States-China Economic and Security Review Commission, an organization created by the U.S. Congress, claimed that Jinan is the home of a Chinese military reconnaissance office.An anonymous cyber security expert believes, despite Google not referring to the Chinese government in the latest attack claim, the company is targeting the Chinese government by listing the victims of the attacks as those whom only the Chinese government are interested in."Both their intentions and the timing of the accusation are dubious," Dai said.Google's accusation followed on the heel of the reported Pentagon's first formal cyber strategy. The Wall Street Journal reported Tuesday that the Pentagon concluded that computer sabotage coming from another country can count as an act of war and the United States may respond by using traditional military force.Li Shuisheng, a research fellow with a top military science academy of the People's Liberation Army, believes there are political motives behind Google's accusation.Google may well have attempted to instigate a new round of the cyber row between China and the United States, Li said.Wednesday's accusation by Google came more than a year after the company allegedly uncovered a cyber attack on its systems that it said it traced to China.In January, 2010, Google said it had been attacked by hackers supported by the Chinese government, and later announced to withdraw from Chinese mainland. The row ended up with Google redirecting Chinese mainland users to a site in Hong Kong.In such cyber attacks, it is easy to locate the IP address of hackers but hard to tell where the hackers actually are, said Dai."Hackers usually launch attacks by camouflaging their own IP addresses or controlling computers of others. Therefore, we can hardly tell the location of the hacker unless we have sufficient evidence," he said.China is one of the leading targets of cyber attacks. It has the world's largest number of computers infected with bot, a type of malware which allows a cyber attacker to gain control over the affected computer.About 13 percent of the world's computers infected with bot are in China."Without cooperation between governments, absolute security cannot be guaranteed in cyber community," said Li , adding only cooperation can ensure safe information exchange.

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.

WASHINGTON, June 16 (Xinhua) -- Cells in the human body are constantly being exposed to stress from environmental chemicals or errors in routine cellular processes. While stress can cause damage, it can also provide the stimulus for undoing the damage. New research by a team of scientists at the University of Rochester has unveiled an important new mechanism that allows cells to recognize when they are under stress and prime the DNA repair machinery to respond to the threat of damage.Their findings will be published Friday in journal Science. Cells in the human body are constantly being exposed to stress from environmental chemicals or errors in routine cellular processes. While stress can cause damage, it can also provide the stimulus for undoing the damage.The scientists, led by biologists Vera Gorbunova and Andrei Seluanov, focused on the most dangerous type of DNA damage -- double strand breaks. Unrepaired, this type of damage can lead to premature aging and cancer. They studied how oxidative stress affects efficiency of DNA repair. Oxidative stress occurs when the body is unable to neutralize the highly-reactive molecules, which are typically produced during routine cellular activities.The research team found that human cells undergoing oxidative stress synthesized more of a protein called SIRT6. By increasing SIRT6 levels, cells were able to stimulate their ability to repair double strand breaks. When the cells were treated with a drug that inactivated SIRT6, DNA repair came to a halt, thus confirming the role of SIRT6 in DNA repair. Gorbunova notes that the SIRT6 protein is structurally related to another protein, SIR2, which has been shown to extend lifespan in multiple model organisms."SIRT6 also affects DNA repair when there is no oxidative stress," explains Gorbunova. "It's just that the effect is magnified when the cells are challenged with even small amounts of oxidative stress."SIRT6 allows the cells to be economical with their resources, priming the repair enzymes only when there is damage that needs to be repaired. Thus SIRT6 may be a master regulator that coordinates stress and DNA repair activities, according to Gorbunova.

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."

HAVANA, Aug. 15 (Xinhua) -- Cuba's Ministry of Public Health launched an intensive sanitation campaign Monday against the Aedes Aegypti mosquito, which can spread dengue fever.The operation, which is running through Sept. 15, will cover the most vulnerable cities in the country, including the capital Havana and the eastern city Guantanamo.Deputy Health Minister Luis Estruch stressed the importance of the prevention campaign and urged all families to check their houses for mosquitoes each week.Maria Guadalupe Guzman, director of the Pan-American and World Health Organization Cooperation Center for the Study of Dengue and Its Vector at the Pedro Kouri Institute of Tropical Medicine, said the epidemiological situation in the country is stable. However, she warned that an epidemic outbreak is still possible in the island state, given the high temperatures and heavy rains in the eastern areas, and drought in the west.Cuba, along with Chile and Uruguay, are the only Latin American countries where dengue is not endemic.In 1981, the country suffered its worst dengue outbreak in history, which left 158 dead.