GelMan and Quad Guard Flak Jacket. Dr. Amit Bagchi, Dr. Peter Matic, and Dr. Thomas O'Shaughnessy (left to right) use GelMan surrogates, made of synthetic bones and soft tissue, to test helmets and armor for the military. "Our job is to provide some basic understanding of what's going on," says Matic. "Then we can contribute to the design and selection of the best protective equipment." Courtesy of US Naval Research Laboratory; photo by Jamie Hartman