Fluctuation bounds on charge and heat diffusion
  We study thermal fluctuation corrections to charge and heat conductivity in systems with locally conserved energy and charge, but without locally conserved momentum. Thermal fluctuations may naturally lead to a lower bound on diffusion constants for thermoelectric transport, and need to be taken into account when discussing potential bounds on transport coefficients. 
Pavel Kovtun
cond-mat.stat-mech hep-th