Geodesic flows and their deformations in Bertrand spacetimes
  In this article we will discuss some features of a particular spacetime called Bertrand space-time of Type II (BST-II). The talk discusses about the energy conditions and the ESR parameters in this spacetime. 
Prashant Kumar, Kaushik Bhattacharya, Tapobrata Sarkar
gr-qc hep-th