Author(s): J. Prost, J.-F. Joanny, and J. M. ParrondoThe fluctuation-dissipation theorem is a central result of statistical physics, which applies to any system at thermodynamic equilibrium. Its violation is a strong signature of nonequilibrium behavior. We show that for any system with Markovian dynamics, in a nonequilibrium steady state, a proper ch...[Phys. Rev. Lett. 103, 090601] Published Mon Aug 24, 2009