  Certain aspects of nonrelativistic diffeomorphisms in 2+1 dimensions are
investigated. These include a nonrelativistic limit of some relativistic
actions in 3 dimensions, the Seiberg-Witten map, a modification of the
viscosity tensor in particular due to a non-uniform magnetic field, a
redefinition of background fields, and 1/R terms on Riemann surfaces of
constant curvature.
