A tensor instability in the Eddington inspired Born-Infeld Theory of Gravity
ArXiv 1204.1691 (2012)
Abstract:
In this paper we consider an extension to Eddington's proposal for the gravitational action. We study tensor perturbations of a homogeneous and isotropic space-time in the Eddington regime, where modifications to Einstein gravity are strong. We find that the tensor mode is linearly unstable deep in the Eddington regime and discuss its cosmological implications.A tensor instability in the Eddington inspired Born-Infeld Theory of Gravity
(2012)
Ricci focusing, shearing, and the expansion rate in an almost homogeneous Universe
(2012)
Ricci focusing, shearing, and the expansion rate in an almost homogeneous Universe
ArXiv 1204.0909 (2012)
Abstract:
The Universe is inhomogeneous, and yet it seems to be incredibly well-characterised by a homogeneous relativistic model. One of the current challenges is to accurately characterise the properties of such a model. In this paper we explore how inhomogeneities may affect the overall optical properties of the Universe by quantifying how they can bias the redshift-distance relation in a number of toy models that mimic the real Universe. The models that we explore are statistically homogeneous on large scales. We find that the effect of inhomogeneities is of order of a few percent, which can be quite important in precise estimation of cosmological parameters. We discuss what lessons can be learned to help us tackle a more realistic inhomogeneous universe.Detecting Abnormal Patterns in Call Graphs Based on the Aggregation of Relevant Vertex Measures
Chapter in Advances in Data Mining. Applications and Theoretical Aspects, Springer Nature 7377 (2012) 92-102