Newton-Hooke Algebras, Non-relativistic Branes and Generalized pp-wave   Metrics
  The Newton-Hooke algebras in d dimensions are constructed as contractions of dS(AdS) algebras. Non-relativistic brane actions are WZ terms of these Newton-Hooke algebras. The NH algebras appear also as subalgebras of multi-temporal relativistic conformal algebras, SO(d+1, p+2). We construct generalizations of pp-wave metrics from these algebras. 
Jan Brugues, Joaquim Gomis and Kiyoshi Kamimura