  A study using UrQMD is presented concerning the higher moments of net protons
from Au+Au collisions at 7.7, 11.5, 14.6, 19.6, 27, 39, 62.4, and 200 GeV,
concentrating on $C_{4}/C_{2} = \kappa\sigma^{2}$. Higher moments of net
protons are predicted to be a sensitive probe of the critical point of QCD. At
the QCD critical point, particular ratios of the moments of net protons are
predicted to differ from the Poisson baseline. Recently STAR has published the
higher moments of net protons for Au+Au collisions at $\sqrt{s_{\rm NN}}$ =
7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeV. UrQMD quantitatively reproduces
STAR's measured $C_{4}/C_{2} = \kappa\sigma^{2}$ for net protons for all Au+Au
collisions more central than 30\% and at all centralities for $\sqrt{s_{\rm
NN}}$ = 7.7 and 11.5 GeV. The effects are investigated of three different
centrality definitions on the values of $C_{4}/C_{2} = \kappa\sigma^{2}$ from
UrQMD calculations including the impact parameter given by UrQMD. It is shown
that using a centrality definition based on multiplicity to calculate the
higher moments of net protons gives a biased answer for $C_{4}/C_{2} =
\kappa\sigma^{2}$, except in the most central bin (0-5\%).
