The World Health Organization on Monday raised its alert level from three to four on its six-level scale.

CNN: World battles swine flu as death toll rises

The move from level three to level four on the WHO's six-level threat scale means the world body has determined the virus is capable of significant human-to-human transmission -- a major step toward a flu pandemic, said Dr. Keiji Fukuda, the agency's assistant director-general.

CNN: The story

The International Atomic Energy Agency has classified the Tokaimura accident, which was the worst in Japanese history, as level four on its seven-point scale, making it the world's most serious since the level-seven disaster at Chernobyl in 1986.

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IPOScoop.com gave Facebook a rating of four stars on a possible scale of five, a level that it hasn't doled out since Visa Inc.

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