  Green-Kubo and Einstein expressions for the transport coefficients of a fluid
in a nonequilibrium steady state can be derived using the Fluctuation Theorem
and by assuming the probability distribution of the time-averaged dissipative
flux is Gaussian. These expressions are consistent with those obtained using
linear response theory and are valid in the linear regime. It is shown that
these expressions are however, not valid in the nonlinear regime where the
fluid is driven far from equilibrium. We advance an argument for why these
expression are only valid in the linear response, zero field limit.
