The see-saw mechanism and heavy Majorana neutrino masses in an SO(10)   model
  We apply the see-saw mechanism and an SO(10) model to neutrino masses and mixing in order to estimate the heavy Majorana masses. We discuss shortly the decay modes of heavy Majorana neutrinos and calculate their contribution to the lepton number violating processes \mu\to e\gamma, \tau\to\mu\gamma and \tau\to e\gamma. 
W. Alles and L. Frassinetti