A "Running" Gravitational Constant?
  If the gravitational interaction is unified with the electroweak and strong interactions at a mass M=10^15 GeV, the evolution of Newton's constant must differ from its classical (general relativistic) form. We can model such behavior by introducing an ad hoc dependence on ln(s/4m^2) where s is the usual cm energy between two protons. We can then predict the observable effects for relativistic collisions (sqrt(s)~1.4x10^4 GeV) as well as for the case of low velocity motion (beta^2~10^-5) 
A.C. Melissinos