Title: Gas accretion as the origin of chemical abundance gradients in distant galaxies

In Cresci et al. (arXiv: 1010.2534) they find 'inverse' metallicity gradients for three rotationally supported star-forming galaxies at z=3. They conclude that the central gas has been diluted by the accretion of promordial gas, as predicted by 'cold flow' models. In Jones et al. (arXiv: 1010.1538) they find a 'normal' metallicity gradient for a lensed z=2 star-forming galaxy. While the physical gradient is considerably steeper than that observed in local galaxies, in terms of the effective radius at that epoch, the gradient is similar. They conclude that subsequent growth occurs in an inside-out manner with the inner metallicity gradient diminished over time due to radial mixing and enrichment from star formation.