But scientists working at the World Health Organization and in its network of laboratories say it doesn't appear SARS has spent much time in the human population.

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The advantage of the rival NTT technique, says Saruwatari Masatoshi, a senior researcher at the company's Optical Network Systems Laboratories, is that it uses only a single light source.

CNN: THE INTERNET

That's when the Centers for Disease Control and Prevention launched a network of 50 specialized laboratories across the country for state-of-the-art analysis of samples from infected patients.

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Annual field workshops were organised in the concerned countries in central Africa, and new data were obtained in various laboratories of the network.

UNESCO: EARTH SCIENCES FOR SOCIETY

For this off-site analysis, the Organisation for the Prohibition of Chemical Weapons (OPCW) - the implementing agency of the Chemical Weapons Convention - has established an international network of highly competent so-called "designated laboratories" that routinely undergo proficiency testing to ensure that their standard of analysis is up to the needs.

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