Misner-brane cosmology
  A brane universe derived from the Randall-Sundrum models is considered in which an additional Misner-like periodicity is introduced in the extra direction. This model solves the ambiguity in the choice of the brane world by identifying the branes with opposite tensions, in such a way that if one enters the brane with positive tension, one finds oneself emerging from the brane with negative tension, without having experienced any tension. We show that the cosmological evolution resulting from this model matches that of the standard Friedmann scenario, at least in the radiation dominated era, and that there exist closed timelike curves only in the bulk, but not in the branes which are chronologically protected from causality violations by quantum-mechanically stable chronology horizons. 
Pedro F. Gonzalez-Diaz (IMAFF, CSIC, Madrid)