Reionization and the Cosmic Microwave Background
  If the COBE detection of CMB fluctuations is used to normalize the power spectrum of primordial density fluctuations in a cold dark matter--dominated universe, early reionization is likely to result in a substantial diminution of primordial temperature fluctuations on degree scales. I argue that the reionization may be non--Gaussian because of feedback effects. Secondary fluctuations on arc--minute scales provide an important probe of the efficiency of rescattering. 
Joseph Silk