  Disordered Fermi-Dirac distributions are used to model, within a
straightforward and essentially phenomenological Boltzmann equation approach,
the electron/hole transport across graphene puddles. We establish, with
striking experimental support, a functional relationship between the graphene
minimum conductivity, the mobility in the Boltzmann regime, and the steepness
of the conductivity parabolic profile usually observed through gate-voltage
scanning around the charge neutral point.
