On the cover: The cover depicts mass cytometric measurement of the cell cycle distribution across specific cell type development from a minimum spanning (hematopoietic) tree. The portion of the periodic table shown reveals the transition elements exploited using the new mass cytometric technology that the authors employ. See the accompanying article by Behbehani et al. in this issue.
Cover design by Bärbel Beran [www.beran-design.de].