Lensing effects in inhomogeneous cosmological models
  Concepts developed in the gravitational lensing techniques such as shear,
convergence, tangential and radial arcs maybe used to see how tenable
inhomogeneous models proposed to explain the acceleration of the universe
models are. We study the widely discussed LTB cosmological models. It turns out
that for the observer sitting at origin of a global LTB solution the shear
vanishes as in the FRW models, while the value of convergence is different
which may lead to observable cosmological effects. We also consider
Swiss-cheese models proposed recently based on LTB with an observer sitting in
the FRW part. It turns out that they have different behavior as far as the
formation of radial and tangential arcs are concerned.
