The Icelandic volcano, located under a glacier, is spewing water vapor and fine-grained ash that can be damaging to aircraft engines. Derrick Ryall of the British Meteorological Office explains the challenges of measuring the size of the plume, where it…

Twitter may be one of the world's fastest-growing social media tools, but the question of how the 140-character micro-blogging site could turn tweets into dollar signs has gone unanswered since its launch in 2006. Until now. The San Francisco-based company…

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