Guest Editors' Introduction to the Special Section on Computational Methods in Systems Biology

This special section contains the second series of journal articles made from a selection of papers presented at the Ninth International Conference on Computational Methods in Systems Biology, CMSB 2011. CMSB is an annual series of conferences, initiated in 2003, on the design of computational methods for modeling and analyzing biological systems, networks, data, and on their applications to study cases. This issue contains the second part which is composed of three papers.“The Propagation Approach for Computing Biochemical Reaction Networks” by Thomas A. Henzinger and Maria Mateescu revisits the chemical master equation, the rate equation and a combination of both, with the concepts of propagation models and propagation data type for abstracting from the further implementation choices made in simulators.“Curvature Analysis of Cardiac Excitation Wavefronts” by Abhishek Murthy, Ezio Bartocci, Flavio H. Fenton, James Glimm, Richard A. Gray, Elizabeth M. Cherry, Scott A. Smolka, and Radu Grosu, which describes a parallel curvature analysis algorithm of cardiac excitation wavefronts.The last paper, “Multiscale Modeling and Analysis of Planar Cell Polarity in the Drosophila Wing,” by Qian Gao, David Gilbert, Monika Heiner, Fei Liu, Daniele Maccagnola, and David Tree proposes the use of Hierarchically Colored Petri Nets to develop models of tissues at different spatial scales.