CINXE.COM

<!DOCTYPE html><html lang="en-US"><head><title>Just a moment...</title><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=Edge"><meta name="robots" content="noindex,nofollow"><meta name="viewport" content="width=device-width,initial-scale=1"><style>*{box-sizing:border-box;margin:0;padding:0}html{line-height:1.15;-webkit-text-size-adjust:100%;color:#313131;font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,Noto Sans,sans-serif,Apple Color Emoji,Segoe UI Emoji,Segoe UI Symbol,Noto Color Emoji}body{display:flex;flex-direction:column;height:100vh;min-height:100vh}.main-content{margin:8rem auto;max-width:60rem;padding-left:1.5rem}@media (width <= 720px){.main-content{margin-top:4rem}}.h2{font-size:1.5rem;font-weight:500;line-height:2.25rem}@media (width <= 720px){.h2{font-size:1.25rem;line-height:1.5rem}}#challenge-error-text{background-image:url(data:image/svg+xml;base64,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);background-repeat:no-repeat;background-size:contain;padding-left:34px}@media (prefers-color-scheme:dark){body{background-color:#222;color:#d9d9d9}}</style><meta http-equiv="refresh" content="390"></head><body class="no-js"><div class="main-wrapper" role="main"><div class="main-content"><noscript><div class="h2"><span id="challenge-error-text">Enable JavaScript and cookies to continue</span></div></noscript></div></div><script>(function(){window._cf_chl_opt={cvId: '3',cZone: "perec.columbia.edu",cType: 'managed',cRay: '922b3dc0ee09fe0d',cH: 'uAGXh57ZUFzYEh9D6E7M1Ft3IF22sY9ArZoymnH4sjI-1742369182-1.2.1.1-sgAlqnQEmPLbje0O83nwi8Z0l8ucCaB72kmhQIJK_4RsE0AD0McAkmtZoL3e_ORZ',cUPMDTk: "\/?__cf_chl_tk=Ec0HopPbrzOXHGrFqxInh2e7MSrpaQ5xtE81ubL7y5Y-1742369182-1.0.1.1-Qu5meM5sZTwrVznBV.g.mHNeHuxl5D_7yY3k3qtwuQ8",cFPWv: 'g',cITimeS: '1742369182',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "",fa: "\/?__cf_chl_f_tk=Ec0HopPbrzOXHGrFqxInh2e7MSrpaQ5xtE81ubL7y5Y-1742369182-1.0.1.1-Qu5meM5sZTwrVznBV.g.mHNeHuxl5D_7yY3k3qtwuQ8",md: "W33HY4QmrEJYo2aWvyTuYaxSXpNbcSUGFC8A8hQULwY-1742369182-1.2.1.1-pcaXocEN9W4fhHGQwTQbV.SrEDGI8LtEKq7L6.CFOvTd0Obhp5loiyh0FwfcpdQG.AWk7gMobCVe2nTv.mT2dOnt0Nq79KCVZSIL_U2rvkPurCsTKa1iTTV4yYHp3wadMChRJDZRhAbp0_dPJmAvG8uNzlViBAZZH6JdlJFEaWsiZJEVIu.LfA8pfv_GS0FemyC7QiEh3hLFLPWGYOaTW8SlEGEUpTG0Gnu0zgEGX1HU_.3ZQQDMCYxoK7GNya4BQws4qFKYE46KzXS3u82JxgNQp6AjkkFhqyzwmGeZymrk3H6Qwz1TSHL3NzBrtvwH5vHUWf4VX5Pub14Gxql4nX8tJPSC2MxcsQaPOnWBB_R9z2jEnpeodGGrIEeqVH5_mUDh.oIWiAR8m.fHDJdAw53n6UoKBjhpDKZBZJHxBu65Emm0yRW_935_R3HmE6vWiVLIqWN0ahIx0U1X2DptYlwgSe2NyWqYwttWVHgz1e1Vgpl9qGUlGU7sjsF9e3QWmZUDWmfSP85QqIW0L_CEN.rDpU4JBwaagfUKSZgH_qSeBMPd_ld7MbBY9ALnmHHLCZEZXboMvbzhMMev9INFvwEkad7gOfvomC1xQ55UVD6oi34q6_Bl2lE1RsNAPUqY1wBX49KFmfjTjQvNY1cmoJq_oTTS_ym4PnsawfuKSC7sGHZGk2Zm8SeK7H89psicP7i.sgzQ3k5P3tY7qKZrqWrO3zV6wMcg4zwOGDccM5zw2auS4jeuzmr8bbio2jPid91l62vG0GKoFiwU9nzpAeKJQ8JYjS7cDHSwgdzCQ_yFxQitRtcVGgxi19R0H0_MwN3iL3xzW8._L_wrxmNQgfnto51U3dJ4dmgXjCNAAZ3UnyaNTqwJzs7Au_bzmIGKY8D3nACxZj_K03lXqu0KI4ZwWN4dSxOTbp_1X8TiMNpqOjuASo7ezP4hx0_X6_dOUY_PTxrDnXYNJsWuWwosSQ2Fv8ViSc091hegyVSZOmmZjuPjsxYtrFLXN5d7gZSfM4o2UFImodKMjXbK2vCSqAi8U6tdhqcdPMKOF_nFyguvanPSDm6bauIl0sqhH_yaHDItFGnx2FvnbSWV.0L2h1HZbyln.BBkPUrb_8uqrZTrhUSuwjuSbj_IkIIyHh9FE5bwzP376dFjLnI6.AZlNzw3hThweEnMPGNtM7sU7SIQUmet5WR7JJh3w309ovlF_g.G6dW5whiAr_RU2x3i4g",mdrd: "MPBXCXJeEEMpEB9IAivoOLuaChuNek38RuowMUPLip8-1742369182-1.2.1.1-cl_SzB1KiWhNo13TYC.V8L6RtTwJDkZ2RM.bYWGNJWA0FQGGQfxJmbvVuyW5zkNw1Y_8.0G5OIG9B3hB9Ob5ddBnNIKqeip2rz8Zz.00XML.bBn_ry0uqRAJgTSG1qHZOpOuya077q.NxDiE.G8nwjALhKPCzFljmhKs3HjjWrhN.roJ64Xaj23cNs6faXypdqu7QIZVN4URrMz3af7GITlLwOzIbFJMT2BqNNrn6ERJolky1uFeg0Dk7vWQOJGaVxkaRWLHMVCQL9T.w0hIMvejiUoyUhRF5Tf5xcXviFGk1li0D1GsMRFYg7sVNyNzCrakc7aqpm4xv49h6W_aGT0SRqegIL1WbVlmj7.OpwkzLd9C0_hRVvFBxkba6S3xI2X9TiBbAyPyzl_uHyu6eKiSAfDDSvkRPIkREzo0JF2WEyohvYgCiKpOcZ9Js9yucldZyhzuWr6gbCBLt.Dg84NvLwsMihWOqfo7yU58eksG.huDpG9elRmzC1Jvfn4ExyfonNOK8iXMrSVUBtMaJKLg_dxTv9icFmfIgtxv3QLm3pKTG75jcMm2WX.barGnpHX0Jenxe.65RB3u2jeFv5PkINJKaD2.PdNPwa.PsYSB5KfQrKQrPzaG4xFvG7.Qdab0Kc5JBuYQyVyL9w5uornSrPhouyLTsf4w_84YNlMgOJzedz66KA6gWxH.dH0YRAEkeU81sjQrr7mLSwwAUTdqzqDEIPRN5gWf.FfMTNwMWdP4zJcgZU1XGBmp1RLQUVDvAQ6xDSni_wuGUd0S9sqdlQUuWjUis7XiaODDOr3QHoIJRj76uWEfN.8IAjLpGqOdetKB6E9SZ1.O21GvyjbSFlYb3_qlP0lNkm9UDa_wcTINuU5x3TR0APn38rYk8Thk6iqZA6FhBEefWyje1crXOJMePIG9VBvIDeB0iriQoxlTI0sVCQNRbUbKIgC9wvcRnCJG4elnHr3hqfNS_lh1YqTrIcxF3rrRpsXW.9dga5.iNJyGsdh4RfXwvkzCT6AF5CkdVZsB93Cx.m9IGduEWXvOM7tqVsS3x_sc8j3JbJI7K0vhvjTrA5vJVcGYS6_55ANHIPEI5DnAtSajTiB2LAe9bbx0eec.9hM1KXFJW3teG3hgmvn6vdr6LIeyhhpx3UM6C7_NzscKlPz8esP6Dn17AyoR2aNhmGkR3Lhh34kkfh24gn49Yuf_DEms6AqBVfeqYOajGpZff02vy6lmcLDu9Ms_lF4lejSAIjSW43GlzOeY8f1b6rVnhYuzFNLU0h1j.ZJkvnqy.kzgupRbififUi0dmf6sz9IKo9xntHGXObQO6XZriOT.VLGU3ATT2Z6QU1E5dQUgmJ3hE0ot7Ihwbc5DfjvFtdjrQHlXPTPAtfhZtgRURX13mDMb.61Wt8bd4hSrP.aeb0cve.EdfPhSFtJRBQlqzXUTXAEJLuneoe.66FM4u0RWnzzNhoMXFPYzaefW_kNbBUtEQaX_W758thAXrJ3aVoSa3bs1._AgT.xwSCF0urejauc0omnuXLe388C0KI8kyyp0vE3f3izKxw8wk3DLoq6JAWSBT5_mJZdIYhd.GpdkX.Z.7PXnlxGAMXAkyxASYdp47CgjhrFEzoOV11Zfau_pVf9oErl.WUizvIBPtFIVyrofgfV_qyspMkxh0_kb4Q4VPteCqYMjIiwy8ODV79D3mPqQO5q0t7DbCPKeYARNjqiyEXQTFW232gP_YbpenOw.FeouSHeJDW0JahhDTcv1BPnB8CW9OkJ2r09NIs6PTWcrXhwzGyI.UcLoDHUCjuyWClLp44Y3..jDpZyIbys712KaBoPv7KXS.Kzu1cfxwbv_t7c1bSdxR8KyOqOryxS_ek0ghlRu1SsilHeFUSmLCEVmno9f6f2x4HfIKVpfqmckCE0Y1NAVlE.vNkMJHLMnF_SAh6f_k3LbGOQwfri8fx50gEu3V6Os9GQ6ijdBq8ESHhIEvBJMYL5JEqUFVVSHCpyDydxJf8lDF7h_AwMdd_EGc9b6ZkiNBxAkt4jU.LJBKBpjE4xe9VGaIUwIa60658DYpUulvJtNgDYniFx37TU"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/g/orchestrate/chl_page/v1?ray=922b3dc0ee09fe0d';window._cf_chl_opt.cOgUHash = location.hash === '' && location.href.indexOf('#') !== -1 ? '#' : location.hash;window._cf_chl_opt.cOgUQuery = location.search === '' && location.href.slice(0, location.href.length - window._cf_chl_opt.cOgUHash.length).indexOf('?') !== -1 ? '?' : location.search;if (window.history && window.history.replaceState) {var ogU = location.pathname + window._cf_chl_opt.cOgUQuery + window._cf_chl_opt.cOgUHash;history.replaceState(null, null, "\/?__cf_chl_rt_tk=Ec0HopPbrzOXHGrFqxInh2e7MSrpaQ5xtE81ubL7y5Y-1742369182-1.0.1.1-Qu5meM5sZTwrVznBV.g.mHNeHuxl5D_7yY3k3qtwuQ8" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>