Detection of time-delayed interactions in biosignals using symbolic coupling traces N. Wessel, A. Suhrbier, M. Riedl, N. Marwan, H. Malberg, G. Bretthauer, T. Penzel and J. Kurths EPL, 87 1 (2009) 10004 Published online: 17 July 2009 DOI: 10.1209/0295-5075/87/10004