> http://ej.iop.org/links/q70/VMDjFcWLsjv8u+3qx22qnQ/njp3_1_161.pdf if the link is broken (as it seems now) try one of these http://www.iop.org/EJ/news/-topic=669/journal/1367-2630/1 http://www.iop.org/EJ/abstract/1367-2630/5/1/161/ http://ej.iop.org/links/q29/WnxqUoXJCx+9O5bXFWIrUg/njp3_1_161.pdf