Federal scientists will soon blanket the heart of midtown and the West Village with high-tech sensors designed to track biological, chemical and radiological agents in the event of a terrorist attack. The security project is a first step toward creating a vast network of sensors that can predict how the fallout from a weapon of mass destruction might spread through the city. "We would like to work out what areas would be dangerous and, more importantly, what areas would be safe," said Bruce Hicks, director of the Air Resources Laboratory of the National Oceanic and Atmospheric Administration. The research is...