  We study the nonequilibrium dynamics of a mesoscopic metallic ring threaded
by a time-dependent magnetic field and coupled to an electronic reservoir. We
analyze the relation between the (non-stationary) real-time Keldysh and
retarded Green functions and we find that, in the linear response regime with
weak heat transfer to the environment, an effective temperature accounts for
the modification of the equilibrium fluctuation-dissipation relation. We
discuss possible extensions of this analysis.
