1. WRc plc, Frankland Road, Blagrove, Swindon, SN5 8YF, UK (E-mail: russell_s@wrcplc.co.uk; marshallsay@wrcplc.co.uk)
2. National Centre for Sensor Research, Dublin City University, Glasnevin, Dublin, Ireland (E-mail: bdm@physics.dcu.ie)
3. Aquafin N V, Dijkstraat 8, 2630 Aartselaar, Belgium (E-mail: martijn.devisscher@aquafin.be)