String theory dualities from M theory
  We analyze how string theory dualities may be described in M theory. T dualities arise from scalar-vector dualities in the worldvolume of the membrane of M theory. ``Electric-magnetic'' dualities arise from a duality transformation in M theory compactified on a 3-torus, which takes the membrane into a fivebrane wrapped around the 3-torus. 
Ofer Aharony