Scalar curvature and the existence of geometric structures on   3-manifolds, I
  This paper analyses the convergence and degeneration of sequences of metrics on a 3-manifold, and relations of such with Thurston's geometrization conjecture. The sequences are minimizing sequences for a certain (optimal) scalar-curvature type functional and their degeneration is related to the sphere and torus decompositions of the 3-manifold under certain conditions. 
Michael T. Anderson