Editorial J. Heitzig, J. Graff Zivin, H.D.I. Abarbanel, L. Kocarev and J. Kurths Eur. Phys. J. Special Topics, 225 3 (2016) 423-427 Published online: 25 May 2016 DOI: 10.1140/epjst/e2016-60093-5