  Nonlinear I-V characteristics have been observed in insulating
quench-condensed films which are locally superconducting. We suggest an
interpretation in terms of the enhancement of conduction by the depinning of a
Cooper pair charge density wave, Cooper pair crystal, or Cooper pair glass that
may characterize the insulating regime of locally superconducting films. We
propose that this is a more likely description than the Coulomb blockade or
charge-anticharge unbinding phenomena.
