The two main reasons a soldier can't keep fighting once he's badly wounded are severe hemorrhaging and acute pain. Scientists are exploring the possibilities of using a portable laser to cauterize wounds. The chief glitch so far is that the device blinds the user. Self-administered battlefield acupuncture is also being considered. But even these methods may be too conventional. In a recent speech, Dr. Joseph Bielitzki of DARPA's Defense Sciences Office suggested that soldiers be pretreated for pain before entering combat so they can keep going even after an injury.