1. Central Laser Facility, CCLRC Rutherford Appleton Laboratory, Didcot, Oxfordshire, OX11 0QX, UK (P.M., I.P.C., K.L.R., A.W.P.); Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK (E.R.C.D., A.E.G.); and Institute of Orthopaedics and Musculoskeletal Science, University College London, Stanmore, Middlesex, HA7 4LP, UK (A.E.G.)