  A Maxwell's demon type ``information engine" which extracts work from a bath
is constructed from a microscopic Hamiltonian for the whole system including a
subsystem, a thermal bath, and a nonequilibrium bath of phonons or photons
which represents an information source/sink. The kinetics of the engine is
calculated self-consistently from the state of the nonequilibrium bath, and the
relation of this kinetics to the underlying microscopic thermodynamics is
established.
