RT Journal Article SR Electronic T1 The double helix 50 years on: models, metaphors, and reductionism JF Journal of Medical Ethics JO J Med Ethics FD BMJ Publishing Group Ltd and Institute of Medical Ethics SP 63 OP 64 DO 10.1136/jme.29.2.63 VO 29 IS 2 A1 R E Ashcroft YR 2003 UL http://jme.bmj.com/content/29/2/63.abstract AB