RGMIA digitization. CAVAL 2011 1. The '(r)' in D (r) k (abstract) is superscript 2. The 'k' in D (r) k (abstract) is subscript 3. The 'k' in Dk (abstract) is subscript 4. Mathematical equation (abstract) indicated with *** 5. The 'k' in {αk} (abstract is subscript 6. The 'p' in Mp (abstract) is subscript 7. 'pr' in Fpr (abstract) is subscript 8. The 'r' in Cr (abstract) is subscript. Abstract removed Lyn 27/9/12.