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\noindent Once believed to be relaxed systems, clusters of galaxies are now observed to contain substructure. The amount of substructure observed may prove to be a useful cosmological test; clusters form earlier in a less dense universe, and therefore have more time to relax. \vskip 5pt \noindent We have used N-body simulations to quantify the amount of cluster substructure for cosmologies with $\Omega_o = 1.0,\Omega_o = 0.2,\Omega_o = 0.1$, and $\Omega_o = 0.2, \lambda_o = 0.8$ for initial power spectra $P(k) = Ak^n$ with $n = -2, -1, 0$. Tests used to quantify substructure include the Lee-Fitchett and Dressler-Schectman statistics, as well as a shift in the center-of-mass with density cutoff. We find significantly more substructure in the denser universes. How observable these differences are is currently under investigation.
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