<!DOCTYPE html><html lang="" ><head><title data-test="layout-title">Nature Network</title><script>(function(e){var t=e.documentElement,n=e.implementation;t.className='js';if(n&&n.hasFeature('http://www.w3.org/TR/SVG11/feature#Image','1.1')){t.className+=' svg'}})(document)</script><!--[if IE]><![endif]--><!--[if (gt IE 8)|!(IE)]><!--><link rel="stylesheet" type="text/css" href="/public/resources/shunter-laserwolf/journals/main-22338d90005b438083904c8ddf3b169e.css" media="all and (min-width: 320px)" /><!--<![endif]--><!--[if IE 8]><link rel="stylesheet" type="text/css" href="/public/resources/shunter-laserwolf/journals/main-ie8-22338d90005b438083904c8ddf3b169e.css" /><![endif]--><!--[if IE 7]><link rel="stylesheet" type="text/css" href="/public/resources/shunter-laserwolf/journals/main-ie7-22338d90005b438083904c8ddf3b169e.css" /><![endif]--><!--[if lt IE 7]><link rel="stylesheet" type="text/css" href="/public/resources/globalui/plain-a58868d7e5db6952a639d9a6db33b621.css" /><![endif]--><link rel="shortcut icon" href="/public/resources/favicon-1a4c37479eecbee89280b07dc5e97b9e.ico" type="image/x-icon" /><link rel="icon" sizes="180x180" href="/public/resources/nature-logo-180x180-aadae3759e15d3c1776135ff4ac39df5.png"><link rel="apple-touch-icon-precomposed" href="/public/resources/nature-logo-180x180-aadae3759e15d3c1776135ff4ac39df5.png"><meta name="msapplication-TileImage" content="/public/resources/nature-logo-transparent-144x144-217b33b4d455268a3fb5246a0bfd0c2d.png"/><meta name="msapplication-TileColor" content="#940720"/><link rel="search" href="http://www.nature.com/search/executeSearch" /><link rel="search" type="application/opensearchdescription+xml" href="http://www.nature.com/opensearch/opensearch.xml" title="nature.com" /><link rel="search" type="application/sru+xml" href="http://www.nature.com/opensearch/request" title="nature.com" /><meta name="viewport" content="width=device-width,initial-scale=1.0,maximum-scale=2.5,user-scalable=yes" /><meta name="robots" content="noarchive" /><meta name="access" content="Yes" /><meta name="WT.z_cg_type" content="" /><meta name="WT.cg_n" content="Nature Network" /><meta name="WT.template" content="classic" /><script src="//nexus.ensighten.com/npg/Bootstrap.js"></script></head><!--[if IE 6]><body class="ie6"><![endif]--><!--[if IE 7]><body class="ie7"><![endif]--><!--[if IE 8]><body class="ie8"><![endif]--><!--[if gt IE 8]><!--><body><!--<![endif]--><div class="container" id="container"><nav><div class="cleared mt10 mr0 mb10 ml0 text12 hide-print smaller-welcome "><div class="grid grid-7 single-grid-4"><span class="inline-block visually-hidden"><a href="#content" class="visually-hidden" data-test="welcome-link-skip">Skip to main content</a></span><span class="inline-block"><a href="http://www.nature.com/" class="block brand-text" data-test="welcome-link-home">nature.com</a></span><span class="inline-block icon icon-left icon-bar single-hide"><a href="http://www.nature.com/siteindex" class="block" data-test="welcome-link-sitemap">Publications A-Z index</a></span><span class="inline-block icon icon-left icon-bar single-hide"><a href="http://www.nature.com/subjects" class="block">Browse by subject</a></span></div><div class="grid grid-5 single-grid-8 last text-right"><span class="inline-block text12"><a href="http://www.nature.com/ecommerce/cart/list.action" class="block icon icon-left icon-cart smaller-icon-remove" data-test="welcome-link-cart">Cart</a></span></div></div></nav><div class="content-container cleared"><div class="cleared clear hide-print" id="header"><header><div class="banner-container contrast-text small-space-below js-banner cleared"><div class="banner" style="background-image:url(/header.jpg)"><h1 class="hide-text" data-test="header-product-title">Nature Network</h1></div><div class="small-menu-bar grid grid-12"><form method="get" action="http://www.nature.com/search/executeSearch" id="header-search" class="search-form js-search-form-header search-form-small text12 pin-right" data-test="search-form-header" role="search"><fieldset class="pin-right"><legend class="visually-hidden">Search Nature</legend><label for="header-keyword" class="visually-hidden" data-test="search-label">Search: </label><input type="hidden" name="sp-c" value="25" data-test="search-spc" /><input type="hidden" name="sp-s" value="" data-test="search-sps" /><input type="hidden" name="sp-q-1" value="" data-test="search-spq1" /><input type="search" id="header-keyword" name="sp-q" placeholder="Search" value="" maxlength="200" data-test="search-spq" class="header-search-smaller" /><button type="submit" id="header-search-submit" data-test="search-submit">Go</button></fieldset><div class="search-advanced pin-right header-color- clear"><a href="http://www.nature.com/search/adv_search?sp-q-1=" class="icon icon-left-small icon--arrow-right" data-test="search-advanced">Advanced<span class="smaller-hide"> search</span></a></div></form></div></div></header></div><div class="content cleared"><div class="grid grid-12 box-sizing full-width-print cleared highlighter" id="content" role="main"><h1 class="article-main-title standard-space-below">Nature Network has been discontinued</h1><p>Nature Network was moved to archive in December 2013. For more information please see the <a href="http://blogs.nature.com/ofschemesandmemes/?p=9625">blog we posted at that time</a>.</p></div></div><div class="cleared text12 clear" id="footer"><footer role="contentinfo"><div class="cleared tiny-space-below"></div><div class="background-gradient-sun footer-links position-relative cleared"><div class="grid grid-2 small-grid-4 hide-print"><ul class="footer-link-list clean-list ma0 pa0"><li><a data-test="footer-link-about" href="http://www.nature.com/npg">About <abbr title="Nature Publishing Group">NPG</abbr></a></li><li><a data-test="footer-link-contact" href="http://www.nature.com/npg_/contact">Contact <abbr title="Nature Publishing Group">NPG</abbr></a></li><li><a data-test="footer-link-accessibility" href="http://www.nature.com/info/accessibility_statement.html">Accessibility</a></li><li><a data-test="footer-link-help" href="http://www.nature.com/help">Help</a></li></ul></div><div class="grid grid-2 small-grid-4 hide-print"><ul class="footer-link-list clean-list ma0 pa0"><li><a data-test="footer-link-privacy" href="http://www.nature.com/info/privacy.html">Privacy policy</a></li><li><a data-test="footer-link-cookies" href="http://www.nature.com/info/cookies.html">Use of cookies</a></li><li><a data-test="footer-link-legal" href="http://www.nature.com/info/legal_notice.html">Legal notice</a></li><li><a data-test="footer-link-terms" href="http://www.nature.com/info/tandc.html">Terms</a></li></ul></div><div class="grid grid-2 small-grid-4 last hide-print"><ul class="footer-link-list footer-link-list-last clean-list ma0 pa0"><li><a data-test="footer-link-jobs" href="http://www.nature.com/naturejobs">Nature<span class="visually-hidden"> </span>jobs</a></li><li><a data-test="footer-link-asia" href="http://www.natureasia.com">Nature Asia</a></li><li><a data-test="footer-link-education" href="http://www.nature.com/scitable">Nature Education</a></li><li><a data-test="footer-link-rss" href="http://www.nature.com/webfeeds">RSS web feeds</a></li></ul></div><form method="get" action="http://www.nature.com/search/executeSearch" id="footer-search" class="search-form text12 search-form-footer hide-print" data-test="search-form-footer" role="search"><fieldset class="pin-right"><legend class="visually-hidden">Search Nature</legend><label for="footer-keyword"  data-test="search-label">Search: </label><input type="hidden" name="sp-c" value="25" data-test="search-spc" /><input type="hidden" name="sp-s" value="" data-test="search-sps" /><input type="hidden" name="sp-q-1" value="" data-test="search-spq1" /><input type="search" id="footer-keyword" name="sp-q" value="" maxlength="200" data-test="search-spq" /><button type="submit" id="footer-search-submit" class="background-gradient-mercury" data-test="search-submit">Go</button></fieldset></form><p class="icon icon-left sn-brand-icon-full clear full-width-print"><small data-test="footer-npg-copyright">© Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.</small><small class="block">partner of <a href="http://www.nature.com/info/partners.html" data-test="footer-link-partners">AGORA, HINARI, OARE, INASP, ORCID, CrossRef and COUNTER</a></small></p></div></footer></div></div></div><div class="break-box box-1 js-box-1" id="small-screen"></div><div class="break-box box-2 js-box-2" id="single-column"></div><div class="break-box box-3 js-box-3" id="smaller-screen"></div><div class="break-box box-4 js-box-4" id="standard-screen"></div><!--[if (gt IE 6)|!(IE)]><!--><script src="/public/resources/shunter-laserwolf/journals/main-2ea683a2a5c213a675711e14651f721b.js"></script><!--<![endif]--><noscript><img alt="" id="DCSIMG" width="1" height="1" src="http://statse.webtrendslive.com/dcs0zztfg00000s969s37qoal_2f6z/njs.gif?dcsuri=/nojavascript&amp;WT.js=No&amp;WT.tv=10.2.55" /></noscript></body></html>