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WASHINGTON, Dec. 21 (Xinhua) -- NASA's Dawn spacecraft has sent around 10,000 pictures of the giant asteroid Vesta back to Earth for the first time since its launch in 2007, the U.S. space agency announced Wednesday.The images were taken from an average altitude of 209 km, the closest the spacecraft can get.From the images, scientists could see Vesta's stippled and lumpy surface in great detail, and its many small craters, grooves, and lineaments. The fine scale of the images highlights small outcrops of bright and dark material.With these new discoveries, scientists believe that studying Vesta can help decode the early history of the solar system.Dawn will maintain its low-altitude orbit for another 10 weeks before moving to a higher orbit for another round of photo-taking.Launched in 2007, the 446 million U.S. dollar project aims at studying the chemical composition of Vesta's surface and probing its interior structure.Dawn will leave Vesta in July next year and arrive at the dwarf planet Ceres in February 2015.

BEIJING, Jan. 27 (Xinhua) -- China is committed to helping African nations to improve their abilities for self-development, Chinese Vice Commerce Minister Gao Hucheng said on Friday.Gao, also International Trade Representative of the Ministry of Commerce, made the remarks in an article published by Xinhua ahead of top Chinese political advisor Jia Qinglin's visit to Africa. Jia, chairman of th

WASHINGTON, Dec. 7 (Xinhua) -- Drugs that affect the levels of an important brain protein involved in learning and memory reverse cellular changes in the brain seen during aging, according to an animal study published Wednesday in the Journal of Neuroscience. The findings could one day aid in the development of new drugs that enhance cognitive function in older adults.Aging-related memory loss is associated with the gradual deterioration of the structure and function of synapses (the connections between brain cells) in brain regions critical to learning and memory, such as the hippocampus.Recent studies suggested that histone acetylation, a chemical process that controls whether genes are turned on, affects this process. Specifically, it affects brain cells' ability to alter the strength and structure of their connections for information storage, a process known as synaptic plasticity, which is a cellular signature of memory.In the current study, Cui-Wei Xie, of the University of California, Los Angeles, and colleagues found that compared with younger rats, hippocampi from older rats have less brain-derived neurotrophic factor (BDNF) -- a protein that promotes synaptic plasticity -- and less histone acetylation of the Bdnf gene. By treating the hippocampal tissue from older animals with a drug that increased histone acetylation, they were able to restore BDNF production and synaptic plasticity to levels found in younger animals."These findings shed light on why synapses become less efficient and more vulnerable to impairment during aging," said Xie, who led the study. "Such knowledge could help develop new drugs for cognitive aging and aging-related neurodegenerative diseases, such as Alzheimer's disease," she added.

BEIJING, Jan. 1 (Xinhua) -- Chinese President Hu Jintao and his South Korean counterpart Lee Myung-bak exchanged new year greetings Sunday and announced the start of the "China-South Korea Friendly Exchange Year".In his message, Hu spoke positively of the relations between the two countries. Seizing the opportunity of the 20th anniversary of the establishment of the China-South Korea diplomatic relations, China is willing to work together with South Korea, by launching various exchange programs, to further promote mutual understanding and friendship between the two peoples, deepen communication and cooperation in all sectors, and push for constant progress of the bilateral relationship, Hu said.For his part, Lee said on the basis of the accomplishments achieved over the two decades of the bilateral diplomatic ties, South Korea looks forward to joining hands with China to build a better future for the bilateral relationship.

WASHINGTON, Sept. 30 (Xinhua) -- At least 15 people have been killed amid 84 sickened in 19 states in listeria outbreak traced to Colorado cantaloupes, making it the most deadly U.S. outbreak of food-borne infection since 1998, the Centers for Disease Control and Prevention (CDC) said Friday.Of the 15 victims, five were in New Mexico, three in Colorado, two in Texas, and one each in Kansas, Maryland, Missouri, Nebraska and Oklahoma. Health departments in Wyoming and Kansas have said they are investigating additional deaths that may be connected to the outbreak.The previous toll announced on Tuesday was 13 dead and 72 sick.The Food and Drug Administration on Sept. 14 warned consumers not to eat cantaloupes from Colorado's Rocky Ford region shipped by Jensen Farms. The cantaloupes with the brand name Rocky Ford were distributed from July 29 to Sept. 10 in at least 17 states."Even if some of the cantaloupe has been eaten without becoming ill, dispose of the rest of the cantaloupe immediately. Listeria bacteria can grow in the cantaloupe at room and refrigerator temperatures," the CDC said.Listeria is a common bacterium that typically causes mild illness in healthy people, but can cause severe illness in older people and those with compromised immune systems. It also can cause miscarriages and stillbirths in pregnant women and severe infections in new babies.Listeria infections lead to about 1,600 serious illnesses each year and about 260 people die, according to the CDC.The CDC estimates that about 48 million people in the U.S. each year get sick from tainted food, with about 128,000 hospitalized and 3,000 deaths.