Cover picture: Simulation of propagating Ca²⁺ wave in a mammalian ventricular cell (starting from top to bottom, left to right). The Ca²⁺ wave propagates by sequentially activating Ca²⁺ release units (white dots) spaced 2 m apart horizontally (along the long axis of the cell) and 0.8 m vertically (perpendicular to the long axis). The white curves show where the Ca²⁺ concentration is between 10 and 20 M. Isolated spontaneous Ca²⁺ sparks occur in images 6, 10, and 11. The 12th image is a linescan image of the Ca²⁺ wave. See the article by Izu et al. on p. 103.