Text and Data Mining valid from 2015-05-22
Received: 20 February 2015
Accepted: 8 April 2015
First Online: 22 May 2015
Change Date: 27 July 2015
Change Type: Update
Change Details: The version of this Article previously published quoted an incorrect abbreviation for Gregory Lee Szeto in the 'How to cite this article' section. This has now been corrected in both the PDF and HTML versions of the paper.
: The authors declare no competing financial interests.