1/f Noise in a Coulomb Glass
  At low temperatures electron hopping in a three dimensional Coulomb glass produces fluctuations in the single particle density of states and hence in the resistivity. This results in a low frequency resisitivity noise spectrum which goes as (1/f)^(alpha) where alpha is very close to 1. This holds down to extremely low frequencies. 
Clare C. Yu (Univ. of California, Irvine)