Reader Comments (4)

Post a new comment on this article

  • 2 Responses
    10 Sep 2013
    19:57 GMT
    Most Recent
    A clarification Posted by johnaltringham on 04 Jul 2012 at 10:40 GMT
  • 0 Responses
    15 Jun 2012
    23:46 GMT
    Most Recent
    Media Coverage of This Article Posted by PLOS_ONE_Group on 15 Jun 2012 at 23:46 GMT