Spherical Tetrahedra and Invariants of 3-manifolds
  Motivated by the Turaev-Viro invariant of 3-manifolds, we construct a formal topological invariant of closed, oriented 3-manifolds involving spherical tetrahedra as an application of the asymptotic formula of 6j symbols for the Quantum Enveloping Algebra of sl(2). This invariant can be considered as a spherical version of a formal invariant of Ponzano-Regge and Korepanov defined via Euclidean tetrahedra. 
Yuka U. Taylor and Christopher T. Woodward