Barycentric coordinate neighbourhoods in Riemannian manifolds
  We quantify conditions that ensure that a signed measure on a Riemannian manifold has a well defined centre of mass. We then use this result to quantify the extent of a neighbourhood on which the Riemannian barycentric coordinates of a set of $n+1$ points on an $n$-manifold provide a true coordinate chart, i.e., the barycentric coordinates provide a diffeomorphism between a neighbourhood of a Euclidean simplex, and a neighbourhood containing the points on the manifold. 
Ramsay Dyer, Gert Vegter and Mathijs Wintraecken
math.DG cs.CG