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It has been recently claimed that cosmologies with time dependent speed of light might solve some of the problems of the standard cosmological scenario, as well as inflationary scenarios. In this letter we show that most...

We fit the BOOMERANG, MAXIMA and COBE/DMR measurements of the cosmic microwave background anisotropy in spatially flat cosmological models where departures from standard recombination of the primeval plasma are parametri...

We consider astronomical and local bounds on the time variation of fundamental constants to test some generic Kaluza-Klein–like models and some particular cases of Beckenstein theory. Bounds on the free parameters of t...

We propose to generalize Bekenstein model for the time variation of the fine structure "constant" αem to QCD strong coupling constant αS. We find that, except for a “fine tuned” choice of the free parameters, the e...

We discuss observational constraints coming from CMB and type Ia supernovae, for the model of accelerated universe produced by gravitational leakage into extra dimensions. Our fits indicate that the model is currently in...