CIRB Biocomputing Unit, Laboratory of Biophysics, Department of Biology, University of Bologna, via Irnerio 42, 40126 Bologna, Italy. Piero@biocomp.unibo.it|CIRB Biocomputing Unit, Laboratory of Biophysics, Department of Biology, University of Bologna, via Irnerio 42, 40126 Bologna, Italy. Piero@biocomp.unibo.it