Supersymmetric Gauge Theories and Gravitational Instantons
  Various string theory realizations of three-dimensional gauge theories relate them to gravitational instantons, Nahm equations and monopoles. We use this correspondence to model self-dual gravitational instantons of $D_k$-type as moduli spaces of singular monopoles, find their twistor spaces and metrics. 
Sergey A. Cherkis (Cal Tech)