Acknowledgement
The authors would like to thank Lauren Constable at Expert Reviews Ltd for her helpful comments.
Financial & competing interests disclosure
This work was supported by grants from National 863 Project of China (No. 2006AA02Z440) and Chinese Funding for Social Public Interests (No. 2005DIB4J041). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.
No writing assistance was utilized in the production of this manuscript.