A New Version of Dirac's AEther and Its Cosmological Applications
  We propose a new formulation for the AEther of Dirac based on a lagrangian approach. We analyse how the presence of a particular self-interaction term in the lagrangian lead us to a description of the aether as being a medium with conductivity which is governed by macroscopic Maxwell equations with a polarization tensor M_{\alpha\beta} depending on the vector potential. These results are then applied to the analysis of the amplification of the primordial magnetic induction in a curved background of Friedmann's geometry. 
Marcelo Carvalho and A. L. Oliveira