“…44,46 Interestingly, in systems that show conductivity jumps the Ohmic conductance shows a simple activation rather than VRH behavior. 43,45 It has become common 41,42,44,45,47,48,49,50,51,52 to attribute strong nonlinearity and S-shaped I-V to electron overheating. It is assumed that G is the function of the electron temperature T e , which can be much higher than the ambient temperature T .…”