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Loop quantum cosmology has provided a large set of insights about the dynamics of loop quantum gravity, based on symmetric (sometimes exactly solvable) model systems combined with advanced perturbation techniques around them. Starting with an exactly solvable, harmonic system (which happens to illustrate singularity resolution by providing examples for bouncing solutions) a systematic perturbation theory is set up. As a key challenge, it remains to formulate general inhomogeneities in a fully consistent way, respecting space-time covariance. Only if this is achieved can loop quantum gravity provide a valid proposal for a modified-gravity theory with quantum corrections, and by this gain access to observational constraints. Recent progress in this direction is described. [ABSTRACT FROM AUTHOR]

In this note cosmological models coming out of the String Field Theory (SFT) in application to the Dark Energy are reviewed. A way of solution construction in case of linear models is outlined, cosmological perturbations and observational evidences of such models are explored. [ABSTRACT FROM AUTHOR]

We propose a model based on a DBI action for the unification of dark matter and dark energy. This is supported by the results of the study of its background behavior at early and late times, and reinforced by the analysis of the evolution of perturbations. We also perform a Bayesian analysis to set observational constraints on the parameters of the model using type Ia SN, CMB shift and BAO data. Finally, to complete the study we investigate its kinematics aspects, such as the effective equation of state parameter, acceleration parameter and transition redshift. Particularizing them for the best fit one appreciates that an effective phantom behavior is preferred. [ABSTRACT FROM AUTHOR]

I review recent work with Ben Craps and Thomas Hertog[1] on the quantum resolution of cosmological singularities using the AdS/CFT correspondence. In particular, we study a five dimensional cosmology, showing that one can define a consistent quantum evolution of the dual boundary theory across the classical singularity. An intriguing consequence of the instability, approximate scale-invariance, and asymptotic freedom of the boundary theory is that an approximately scale-invariant spectrum of stress-energy perturbations is generated. I briefly comment on four dimensional generalizations and the implications for cosmological perturbations in the bulk. [ABSTRACT FROM AUTHOR]