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: "scopeblog.stanford.edu",cType: 'managed',cRay: '92918ff7487e9c5c',cH: '7flue_gnnxSJGwKs4GFq2ajPYRkRS4tbnth7A3D.S3M-1743442097-1.2.1.1-94BOQ8cfW4nGCDI.TJOjm2Q4Qi8kmCEMulWGDGySpwpwVyPAH3D7ExoEKVp6KPb.',cUPMDTk: "\/2016\/04\/?__cf_chl_tk=jMxSSjXoxe7d4V0.BT.VZw2KJKyLPC80_vMbnujvRmg-1743442097-1.0.1.1-YruRTSp44LOAk8wnl2m92k0Tq5YkG5S695c_G_X92rc",cFPWv: 'b',cITimeS: '1743442097',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "",fa: "\/2016\/04\/?__cf_chl_f_tk=jMxSSjXoxe7d4V0.BT.VZw2KJKyLPC80_vMbnujvRmg-1743442097-1.0.1.1-YruRTSp44LOAk8wnl2m92k0Tq5YkG5S695c_G_X92rc",md: "7paNij1va5Hbnz9hWMomiibDtjWDApU_MexaOCwBEtI-1743442097-1.2.1.1-krPbhcT0UpWquDEYc79nOmDXMNofb5P_p9to825g1T6iv5l77Fvcw8Z6I8.DefVhznHpoY6NZXeDtY9KMMJltMYWokEjjYsw0s5FmS62JXkBLHSw3_dQUBZCc.wV.KC_gS1Hz8gQb9vsKDH28HaXMibBj88qteQa6vqNXp5j6gLtk8CGgsSzIt4ItU71VWndHnX4Bj6KF4tTcEA9NJG1fyK8n3wslFEFWgzkQ20VxIlHKLt3cCY7SrGiZgklDpA5_JtJjVw29Xl3KyMeiF19VDihGn3.OBnEghNTLKv0RFAUANs.Y5cOKGxG.K3SJgMwucRm9yQDSE1l8fQyL93m9CpJ.FqOPc3HDDo2VEBHf5yQMhDG5emiTGRmEWxNnWLAqv9edNC_03wBaTzYUXUxOUwwieQo8e74dxmlkNLFwgZ0kHOTJ0wueKVFnTtTn5RJ0ABn1e.iJecgo8gD3V6FRzhAcDqnByPfyQgQDUP0h..5f9sPEMURuCZynEv8NuE.rcbUx8Fm3ixhzh9e9DPlCIvIgqux5Wng6gqCsSp8JU2tzU.2xjFSD4C6whAVZCgiEJr9Oxver5Hx7v33B8w8An5f.WKyagxg0qeHFG63Qtz7Whe4S0igYBPkekQ.X3psHZOcpZ6larva8NRkeyhfbV0wb1Sx50OekXGZaiCRFaJPYq9oYSCmoTDIwd8OugMFQJLu9xOstAjydTHMr_nVy12jhjS6nVtfkmnKWlhUrrHpDFrHB7AoT2IvR5ZNOpJpHozbIEfRoZt90KEAy3.Ab35Y.7jMtigImhqp90xq8pjbJZl.7dWy1wPeAq2ocYB46XjEnzEipbeD67wcxb3UhEVVNMyGwfQjgKmOyqYgPyQM9YTp6mlW_7Z2RPAS58r6dZTYZVHwHQ9wsTT4To06cJlbNNWYeblw9OX_1_wIalefk_rKobmTQ262ZbqJDi1e81Z2GJjXCl6XtseXvDlgRcbwaGJ9LUqZHA.qHyNFb9hTqwtONHJdcHVEmCvK9fpXx2oNTyWM4kvbmMqyAfJIdIDXi39wp1oweUeTg0ZbkGBvjGL8RH53CHmXctARspUP7me4_gh5WrVWw1b2D_.X4DpwwWW4eI5oI6SnmX9QMBu7b0OHMVQZ9rbw_RciEHVhgaPBsOO1_rir26H1ulfg01SUK_Uwj6kufigzj.xonwqGM3ESiuh6T21Ohmee377tzuFA0Qv0i4h_P.KKE3nhQiViBv6e9giO6i2L5RcBKVgaWI8LhfCAntIxHKb1ljzW",mdrd: "oLavlD6V.Uc8f8ZRlIXPXBE3u5IBr8NurqvOfWZf6hg-1743442097-1.2.1.1-xMbfBOiRytlmUpENtORbXSnAzJVR30P3frUuzOU8QvaYyRJ4y8Ryf3uXN0ip4YySz2BrkZgqxnNarOF_yZJC9yt739EjQAMlFVZUc6cGLt4xegeKQ3P0zRo8qSHZ56QiNlBpUZ6Jlr_7mMhl8kX_dfLehszNeu21yn_oROPKizM9z6wXmAeiG6zKItv2pbFkbyjqU6a6DKHtBYf0jiKSadbkSpKACPjyB0tG4iwRt0JjLjXcX_6ivV4ApdYOz5zS5bn4VzAa3DjeJtOZl_9jHKqRwekgnYX3rylRrea7yzhIEZRYm5TmZrqlcOpZdHorX8hQRnhiADTSuFc6Owknvt.CkK8B0Pg5y_HWRC64nW2VqsshhxXoJ2g_aPcRPr1fnwE0yLIpagq0Bs6fvznypb6FYyS.3erg2FcaP5TLZJKRXj5UxegPkj3iY8hEYPmLGooJI4xzf4yPa1G_gPO0eYotzLa5i3aLEU.Tifw6hZ04NfLvMma.DkVKVkKAZQIA69PsRP6zxsuWt6FFUkrhhPcx5vre_u3MY4xSGH9M3GJXatG9TTfrzFATSet5CoXbGLCLUkv2lF2bKfDj2mRRSO_3hpwT7_KQhu8Rs1fmsVB6Wsro7NS.hHYRxk2VGWyA8oYHwFph51uzu.0oPEggAj8eFiMhxn8P4QUYvvpBQ1LrmVTvCUUTtCPId6Fi64MgbJO9G_aS7xl9iC7Rrqx.2IY2ZZZH9_sTm.XWhy8BvrP2_4_ObH5ma194JDIqMqEFqMrWFzQGk6_vIaBV4ewyOwGnmmPT8N5J4Jiat0b2K6gHbCzyqNTgiY0lOlZ6zzrh5gcURaKGRkUzF2mVnxKnv4UDI3DJIBK7M9AsX9OCrrWs1GgYjacYpHEQfJp2V3XsmjX8XTGh7o4JxUwQnKwevWHVLxpEYcZq_bdV9IuqIqhOW83VQ21c_AuJRJIDa.UkPA2Hj6NYbtIKEU0A_ynbVraw6bB0yOrECZ_J4ah9JVjUXcp8DkEh1cfKcdgePZDNYMWA2mh85vTpi5Pc2KCP1Pd.w_IRM1kFufRg68eZhAHrfehle8bsH7jgDPAn7QaHtGpnRnhcCGak2cfY24q.w3nMKYxGIibrwBgHfZZLtOhdKuc6HqVCi9qomGB1qGD2nyNSvkx8tIT1IbUJN4tLqvMY7ipb8XtyOi5NeV9WHycoKfFpZfASgxMN5M7gJ2iL.3yRD778Vv9dxdLjNAdnHDaUPwIthGMx2GqTY1EYPF0EIdeEvRo8IxIDD7NdlLlTzvRJfyy9JpTNzO3TUJNS9GEryjTpEA3XOfCASnVoU.eERMrLICahF6EPl2qQEyx0K8CXjjNWs_46xssrwmDyaFwx76B5EkiLE3WMNGlRSdWs6xF.zC8RULlfcllODhzNYLtlZBhVoaWwz06m0XTn1HaZGjWEEqJVF.pbEVWvNFtKpi0RxC9_nOe3vOTdVjE8co71u.2a6mApzwk3IxSGeXAg1Bp9_xE62bWjM_DC1A6xDGSc89APa4Yd40WchHL_qCDCEb.wsF89ZB1wgS6MDEdjL7VXgpqBBftaVLN4ta5d_M6wRhIG3sRuNYW57vE2LFEXT46LI.LHQtnSPMceDdTVhppvU6lPPzU4U4OLxLuq4aSkzP91bth2cjTVBooq5TK_stf_p7mdNXWBiMfX1QZ.yNDL26qHboYgZeixY_zu5LPWjulxl0TAZ1IcMGYfL837Cs8ZF.m94yRjylw9gX4CnC4Lhgr4chCiWsXTsWeaV1YV4B4DPN_VfsKxqRqVulCaGXB3fGjlA9xNY_Gk8OAvsWNp4og0q6X3KsZVCQXkljP5mZul_2_5fWr5rInlk3sVzxhD32..PTfHtILcV1Jg36_YxTGRyBxcWoWIOGX.JX3GHkJ3Vlos7cdmgt2WX2WLeGbuSdksKAZ4Evo1YXu3VF6qlZxQjtzZHC3ZL8Xp83J5KVC7YF723LrCIUecloymjL5vkBedmvXo_dIHI2zICk4StkMhJ5lejMZgz5a.ubCPLi5neoWph6Q7FzcFiaLEvH8gNk5SLeRa3FCYU3H0.eZPQbq6jent4AboXZ.gPd7AeVKyC0CpJGlITJqa"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92918ff7487e9c5c';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, "\/2016\/04\/?__cf_chl_rt_tk=jMxSSjXoxe7d4V0.BT.VZw2KJKyLPC80_vMbnujvRmg-1743442097-1.0.1.1-YruRTSp44LOAk8wnl2m92k0Tq5YkG5S695c_G_X92rc" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>