6 research outputs found
Higher likelihood of 6-months exclusive breastfeeding among HIV infected than uninfected mothers: a household survey in Kenya
Stability of the Einstein static universe in f(R, T) gravity
The Einstein static (ES) universe has played a major role in various emergent
scenarios recently proposed in order to cure the problem of initial singularity
of the standard model of cosmology. In the herein model, we study the existence
and stability of ES universe in the context of modified theories of
gravity. Considering specific forms of function, we seek for the
existence of solutions representing ES state. Using dynamical system techniques
along with numerical analysis, we find two classes of solutions: the first one
is always unstable of the saddle type while the second is always stable so that
its dynamical behavior corresponds to a center equilibrium point. The
importance of the second class of solutions is due to the significant duty they
have in constructing non-singular emergent models in which the universe could
have experienced past-eternally, a series of infinite oscillations about such
an initial static state after which, it enters through a suitable physical
mechanism, to an inflationary era. Considering specific forms for the
functionality of , we show that this theory is capable of providing
cosmological solutions which admit emergent universe (EU) scenarios. We also
investigate homogeneous scalar perturbations for the mentioned models. The
stability regions of the solutions are parametrized by a linear equation of
state (EoS) parameter and other free parameters that will be introduced for the
models. Our results suggest that modifications in gravity would lead
to stable solutions which are unstable in gravity model.Comment: 27 pages, 6 figures, major revisio