The n_s - T_c correlations in granular superconductors
  Following a short discussion of the granular model for an inhomogeneous superconductor, we review the Uemura and Homes correlations and show how both follow in two limits of a simple granular superconductor model. Definite expressions are given for the almost universal coefficients appearing in these relationships in terms of known constants. 
Y. Imry, M. Strongin, and C. C. Homes
cond-mat.supr-con