Scientific Reports 2, Article number: 731 (2012); Published: 12 October 2012; Updated: 25 March 2013

Due to a technical error, the corresponding author is incorrectly given as Thomas M. Gernon rather than Rex N. Taylor in the HTML version of this Article. For correspondence and requests for materials, please contact Rex N. Taylor (rex@noc.soton.ac.uk). This error has now been updated in the original Article.