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    • The cosmological perturbed lightcone gauge 

      Elmardi, Maye (MDPI, 2018)
      The lightcone gauge is a set of what are called the observational coordinates adapted to our past lightcone. We develop this gauge by producing a perturbed spacetime metric that describes the geometry of our past lightcone ...
    • Shear-free anisotropic cosmological models in f (R) gravity 

      Abebe, Amare; Momeni, Davood; Myrzakulov, Ratbay (Springer, 2016)
      We study a class of shear-free, homogeneous but anisotropic cosmological models with imperfect matter sources in the context of f(R) gravity. We show that the anisotropic stresses are related to the electric part of the ...