Cover picture: Each column shows calculations of the release flux underlying evoked Ca²⁺ sparks in rat ventricular myocytes loaded with the Ca²⁺ indicator fluo-4. The top row shows original spark records and the second row an estimate of release flux derived from an inverse algorithm. The third row shows the same Ca²⁺ sparks with optical blurring removed. The bottom row shows computer simulations of Ca²⁺ sparks obtained with a release flux fitted to the deblurred data. See the article by Soeller and Cannell on p. 2396.