1. Engineering Mathematics Department, University of Bristol, Bristol BS8 1TW, U.K.
2. Department of Electrical Engineering and Information Technologies, University of Naples Federico II, 80125 Naples, Italy
3. Department of Mechanical Engineering, Imperial College London, London SW7 2BX, U.K.
4. BrisSynBio, University of Bristol, Bristol BS8 1TQ, U.K.
5. School of Cellular and Molecular Medicine, University of Bristol, Bristol BS8 1UB, U.K.