<p>Copyright  2013 Hu YJ et al. This is an open access article distributed under the terms of the <a href="http://creativecommons.org/licenses/by/3.0/" target="_blank">Creative Commons Attribution Licence</a>, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Data associated with the article are available under the terms of the <a href="http://creativecommons.org/publicdomain/zero/1.0/" target="_blank">Creative Commons Zero "No rights reserved" data waiver</a> (CC0 1.0 Public domain dedication).</p>
Except where otherwise noted, this item's license is described as <p>Copyright 2013 Hu YJ et al. This is an open access article distributed under the terms of the <a href="http://creativecommons.org/licenses/by/3.0/" target="_blank">Creative Commons Attribution Licence</a>, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Data associated with the article are available under the terms of the <a href="http://creativecommons.org/publicdomain/zero/1.0/" target="_blank">Creative Commons Zero "No rights reserved" data waiver</a> (CC0 1.0 Public domain dedication).</p>