- Correspondence to Dr Jeremy D Keenan, Francis I Proctor Foundation, University of California, 513 Parnassus Avenue, Box 0412, San Francisco, CA 94143-0412, USA;
- Received November 5, 2012
- Revised November 5, 2012
- Accepted November 23, 2012
- First published December 25, 2012.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.