  The temperature dependence of the magneto-conductivity in graphene shows that
the widths of the longitudinal conductivity peaks, for the N=1 Landau level of
electrons and holes, display a power-law behavior following $\Delta \nu \propto
T^{\kappa}$ with a scaling exponent $\kappa = 0.37\pm0.05$. Similarly the
maximum derivative of the quantum Hall plateau transitions
$(d\sigma_{xy}/d\nu)^{max}$ scales as $T^{-\kappa}$ with a scaling exponent
$\kappa = 0.41\pm0.04$ for both the first and second electron and hole Landau
level. These results confirm the universality of a critical scaling exponent.
In the zeroth Landau level, however, the width and derivative are essentially
temperature independent, which we explain by a temperature independent
intrinsic length that obscures the expected universal scaling behavior of the
zeroth Landau level.
