Upper limits for the mass-radius ratio are derived for arbitrary general relativistic matter distributions in the presence of a cosmological constant. General restrictions for the red shift and total… (More)

– In the framework of the varying speed of light theory the Wheeler-DeWitt equation is considered in the minisuperspace approximation. The quantum potential is obtained and the tunneling probability… (More)

We consider solutions with conformal symmetry of the static, spherically symmetric gravitational field equations in the vacuum in the brane world scenario. By assuming that the vector field… (More)

We present a class of exact solutions of Einstein’s gravitational field equations describing spherically symmetric and static anisotropic stellar type configurations. The solutions are obtained by… (More)

We consider quasi-stationary (travelling wave type) solutions to a nonlinear reaction-diffusion equation with arbitrary, autonomous coefficients, describing the evolution of glioblastomas, aggressive… (More)

by means of the conformal transformation ĝμν = egμν . As a particular case these models include Einstein-Maxwell (α = γ = 0) and low energy string theory (α = 2, γ = 2 ). In order to study the… (More)

– Three solutions of the Brans-Dicke theory with a self-interacting quartic potential and perfect fluid distribution are presented for a spatially flat FRW geometry. The physical behavior is… (More)