 Researchers in South Africa have injected radioactive material into the horns of 20 rhinos. It's part of a research project aimed at reducing poaching. Radiation detectors already in place at national borders would detect the horns and help authorities arrest poachers and traffickers. The research has included the participation of both veterinarians and nuclear experts. It begins with the animal being tranquilized before a hole is drilled into its horn and the nuclear material carefully inserted therein.