The intrinsic torsion of SU(3) and G_2 structures
  We analyse the relationship between the components of the intrinsic torsion of an SU(3) structure on a 6-manifold and a G_2 structure on a 7-manifold. Various examples illustrate the type of SU(3) structure that can arise as a reduction of a metric with holonomy G_2. 
Simon Chiossi and Simon Salamon