J. A. Leach

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In this paper we consider a cosmological Friedmann Robertson Walker brane world embedded in a 5-dimensional anti-de Sitter Schwarzschild bulk. We show, using potential diagrams, that for an anti-de Sitter bulk the null geodesics never return to the brane. Null geodesics do however return for k = +1 when we include the Schwarzschild like mass and the(More)
We give the equations governing the shear evolution in Bianchi spacetimes for general f(R)-theories of gravity. We consider the case of R-gravity and perform a detailed analysis of the dynamics in Bianchi I cosmologies which exhibit local rotational symmetry. We find exact solutions and study their behaviour and stability in terms of the values of the(More)
In this paper, we consider an initial-boundary value problem for the Kortewegde Vries equation on the negative quarter-plane. The normalized Korteweg-de Vries equation considered is given by uτ + uux + uxxx = 0, x < 0, τ > 0, where x and τ represent dimensionless distance and time respectively. In particular, we consider the case when the initial and(More)
We study the phase–space of FLRW models derived from Scalar– Tensor Gravity where the non–minimal coupling is F (φ) = ξφ2 and the effective potential is V (φ) = λφ. Our analysis allows to unfold many feature of the cosmology of this class of theories. For example, the evolution mechanism towards states indistinguishable from GR is recovered and proved to(More)
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