  The dependence of the transition temperature $T_g$ in terms of the
concentration of magnetic impurities $c$ in spin glasses is explained on the
basis of a screened RKKY interaction. The two observed power laws, $T_g ~ c$ at
low $c$ and $T_g ~ c^{2/3}$ for intermediate $c$, are described in a unified
approach.

Disordered Systems and Neural Networks