Trained in field theory and worked on constrained systems and supersymmetry including formulations of Einstein’s theory that incorporate spin 3/2 particles, and supersymmetric YangMills models. Present research interests include the following: binaries, triples and their evolution; models for the progenitors of Type Ia supernovae; luminous supersoft X-ray sources, quasisoft X-ray sources and their physical natures; X-ray binaries in external galaxies, especially the ways in which they influence and are influenced by their environments; gravitational microlensing, including by binaries, planets, and nearby stars and stellar remnants.