Two-dimensional photon-echo experiments indicate that excitation energy transfer between chromophores near the reaction center of the photosynthetic purple bacterium Rhodobacter sphaeroides occurs coherently with decoherence times of hundreds of femtoseconds, comparable to the energy transfer time scale in these systems. The original explanation of this observation suggested that correlated flu...

In this note we review recent progress about fluctuation relations and their applicability to free energy recovery in single molecule experiments. We underline the importance of the operational definition for the mechanical work and the non-invariance of fluctuation relations under Galilean transformations, both aspects currently amenable to experimental test. Finally we describe a generalizati...

We consider the Zhang sandpile model in one-dimension (1D) with locally conservative (or dissipative) dynamics and examine its total energy fluctuations at external drive time scale. The bulk-driven system leads to Lorentzian spectra, a cutoff $T$ growing linearly size $L$. show $1/f^{\alpha}$ behavior $\alpha \sim 1$ for boundary drive, varies non-linearly. For local dynamics, shows power-law ...