On cosmological observables in a swiss-cheese universe (Conference   proceeding)
  By means of a toy Swiss-cheese cosmological model we will discuss how to set up and carry out in a physically meaningful way the idea of back-reaction, according to which dark energy could be an effective source. We will follow two distinct approaches. One is focused on how cosmological observables are affected by inhomogeneities, while the other is focused on a theoretical description of the inhomogeneous universe by means of a mean-field description. 
Valerio Marra