Drug-paired conditioned reinforcers can maintain persistent instrumental responding, thus providing a model of some aspects of long-term drug addiction. The purpose of the present study was to ...

Physicists Maria Goeppert Mayer and J. Hans D. Jensen develop a theory of the nucleus as composed of shells of protons and neutrons. It explains why nuclei with certain “magic numbers” of protons and ...

The nuclear shell model of the atomic nucleus, more than 70 years old, stays firmly in place now that researchers from CERN’s nuclear physics facility ISOLDE have shown that the series of magic ...