Cover picture: Counterion condensation around calmodulin. The distribution of the ion density calculated from a 3-ns simulation is compared with that predicted from solution of the Poisson-Boltzmann equation. Calmodulin is represented by its solvent-accessible surface area (white). Left: Three-dimensional histogram sampled from the trajectory. Ion densities correspond to sodium concentrations of 1.0 M (red) and 3.0 M (yellow). Right: Contours correspond to sodium concentrations of 0.1 M (blue), 0.2 M (green), and 0.5 M (yellow). See the article by Wriggers et al. on p. 1622.