CINXE.COM

Just a moment...

<!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="120"></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: "publications.waset.org",cType: 'non-interactive',cRay: '9134185c3abf3f4b',cH: 'WvFuJ0XijqHdlfAqR_Quy_9KwD3hD9XFVQctqYIielk-1739777668-1.2.1.1-c25bOoAt_y7CpLl1Kz57SKy.H54NIYjEwyBo7vZbTaWhqb.tEb3mIpL86LADO.WY',cUPMDTk: "\/10009448\/harvard?__cf_chl_tk=fROsG1Wn.70sV7x5ogkt6wqk5uztSC5e_x.Dtf2Km_A-1739777668-1.0.1.1-NqrVfSmsH21AZge6U_RGvZJESNovpgAHakc5wtPaUsk",cFPWv: 'b',cITimeS: '1739777668',cTTimeMs: '1000',cMTimeMs: '120000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "",fa: "\/10009448\/harvard?__cf_chl_f_tk=fROsG1Wn.70sV7x5ogkt6wqk5uztSC5e_x.Dtf2Km_A-1739777668-1.0.1.1-NqrVfSmsH21AZge6U_RGvZJESNovpgAHakc5wtPaUsk",md: "4O_U8qu6FcKDDS.3_nShIVquBTAPQ3FHVs4_0nR.jrg-1739777668-1.2.1.1-xHPGed9BCQ2DzArvYsJwQIBALXWrz87XXtMSgkzp6z2QGi90v9fFjqHFsw1aelOrqItW_SxMX5NvtZVt246oVjiU6sCTHdUjs4sJrIUZ1pQZYljZMmdH02llJ7tldjiLcoFhUbATecM9ZXudEUo3JCKGA2Jn4ujkxHhR9R09oOUROeVUB9PhOXfehUjJtZWD0OuCq5QSHdPB90vOdyVeYaIy21ntyTiZeUYxRiGFy0DY.2LmLjI.kKpm74Zp_SaTvxb63E9GJFWNUTBOKLtGPgaI76q88RzuNTH7gDBItp84df5rdSZHRoGr3t59puACw0PC2zyGZ47M0ul7CL.nuXg4uA33p2WUiv1Ro2f_k3JVV89XzmV.YvRhNi1Xu_FmnxNtA_tXyWziAKOdUphsbky9udmhXFltd6IZLnuagDQ8eVh79AQ22UEwhbaFv5QA.tXVGdnybyVCop5g.U40hE5uL1.pGaANDWOEAz9lc.H9NlnKPO4jq7joDBt1VJ4iV8pgc2oQUi1Bri.iZBD5xiv5cHa_A3.xOn_nyJ86Gs5lg485KgHAkv48nDMgGXIVP6GL16xTJu773LB1CzUQ6qpSavJ_eE9wnEr6aXGTTrno2rZAOnqc1Ekuw322Ca0Cn6JCUgSilN_Rcop_BkLNt0xxRQq1.bHpzuwi6y2T3Y26wgASsK.K29thQ1.dnJyf8cZBEA5KMbY4CqGB89Jk6JjklkKcxoQGaut8vRgSgR5GUe6qXLIo_8TRhGBSc4vNC8.2wlYb4roXpdgs_FpgHB1NjE9.pjNFseA6bx1Gp7Tcxpuqp7Q54c2ZY1pPrMu_WUGTGNQX80EBZ2qBsxALmlGGHDFebwdnjBe_.VBXjzvDU_rLTr4cDYLff6DXo7mFFb9YnJheh9Mfdkk2waJqLHVYy6Tucevb0w06mELKT26IIHuokTyuqBRDhRrApEgjrOTLdUqSo6h9SjgEisn7Ame..VXMlUOxKpxzE.aBGspNRwxsPIvIif.lmCZj3X.UZvLtEvtPDubMlEpTax5pvdsRDrScQdPLBwwwH0fUyi06WvpA2MTRjidUOge9.SBzlbvckmXuIKm3z56KALr6dsFfE7eime8MxYTUROtC289v3K4gdYuTgXvR3dJb1GOnGlTa7Z7Fe9j9yJvJy6AzhPp8PbNrV43doz1YKiC_0Oo6ALTQqXiXZf5hS0h0uFWu5sNa8Yj.KDRnzVxAnGs8HPYiQF0JDlyl9yzFmAscqabZEzwbcInbPJH47TVtsA_5_gziU0XiNn9hM9op63xAvFfw1jOvZwY.38zgp5auOyNeNp5z785WAOEeRSrfLqLTXq0TMeMisWq7W9ZeK0agRaHB7htnvq6MhKFokCntbEQosFfifMI1KaqtHlFQ9rJnkgKa0r69Gm3c2aQ84POvPaIR7Ihlg55qgBuO2JSduOTM2WAV6fXXUDxVEDvbH6kvMT6L7pOO0gEu1Vi.3pos21oLHj2arM8XwVJBE1jvmxIswyVfreGF1vGuYawhX.GM5UOq37bsmdl0_P0QpaFyR4DjDzXEtGwKrLL8UXsmJNKUCSqus4cKDlse8FSvDdHN2_0oh3HHll8Egta9sFC9B6k0K1p.cc31Sow9wv73PLSu5avE5eQP4kU.J_LaaE5rj.VT4uw8VKDHUw87.Gh792gGoywzSYwPdDUd8iVL2RekMBOe0VlVo4UAKNzaHTjV4Ay.59k5LbfrQdfBM3mZLJaQ5hjES0fIAhc3IaaONtFLvoTdxhu.kF_5ahKVHJfsuEEdXjspt7dOTw060Ctu9t.ds9O7uye.gt9qz0VugbGqQrPKgkLgzPuNgW4IlZWunY2n9rPhPjA.w2LGGacpzd6QOUbzX4R.qCSUmA3dr7w",mdrd: "Uvyq7FktBbO9kQGO0fKRQ7B2xKBLzKMwsYF3Zrymjdw-1739777668-1.2.1.1-4Id886oZHBQ.VVLn8GynyBQM._sdFuUa_AFtItBQWEfSU1N30alZ_O8uJ66AGUU_BViLW7FwMmN.uhyy0DaAzPvYxqg7cFgtJsZnLHItNn0HgY9ZarT9OSykP5KGVfifpym2KZbvcH39qHu65tqI8wSWgzQv668z3ogb0KbpIqyan8ub0mxv52gHd2gYLPt1ITXuX7fXWa_ms0JGw.9I48kGkNl8fL9HOceCKiIEkR7gZMMs5RiVArIq3np2VygRkHZZ2lxEhiQfrBxJAcj3BJzhFUph5imV8s9_a0VqLLZ9zzVrwBUOtJSpYQFDZGkD0zj7NEe5NPEdreXeabDFfBPU9ehwSDi1K3w8qluOqaWESwrcsV8QKwaf3X4Rpuzk9eISUD_lbn5A0MZdRcPeBDTRQ0szyREav2VHqNCNSbsk8MBgEynUL3rfhAdHoZiqJuNPqdAanXqbeaPrWGigVBUuzEdpTHA9PwM5MN8LLpOKF2EshXh79EDh2FiynCrBUDQCu3XI2IK_gYCYUE2q_.qmlv0b0VaBrUanVV0gjnbDrqqrX9U.QnZ8L5D0409mLMdfRLr3HMeukvIYLhZwcYmKGzfF91bTyADsgDATkNAH2Smn2JfgQ_uZomgLZ7I6jEhlVy6QD7Qn0qg_KdIqofCM_3vJ04YMGSM0adTs3yjTG2mfEyaWMAw1cp6AIMbNFh6DUHdb05.6lBs3ViNhovI51iATEW_xixcK3TFw3cOvjJJl.JUXdpbEXMF9wVyTPmkLpr1oCAakb5YYd01BxsAKC6hr8ZHPAaE70ae1vimN8s4M_9zldWsBPpRFZVtY2WFvG.GD4beVrJ2z7pnGAzqlj2ZiUqb4ESrrdshaqq9Dxadzi9rCyxpC.PgrETJ8UVF1htvUtlgcI0h66YDCD2B._QhINAHr3AWcCcAJFJ0iN8IAGxz.HPvhRJCZecKJMX2zsE9pO0GczZ5xf5_aD_QPZxxGCj7WgyHFuBY8qPilb1NJfCun4GbQzjMEG1SBh2yl6KqfXyMmN6MbyBhpNFc9KSuX1eBmgpibAUy5IReGsZz4wM6lIwaLh7E_ACgS.La66rmIydKRVLJUt46bnZI4ySzYkKPBgI.bICUD_DC5LydmeemmS95MwJ2lBlWB0Qhy048mfsVdZNvVsQSivmYLvGd8G4dUGa78KKR.SvqZDhdT60kahXWvLdgVPP9V0Tw5qPsClcTRWGBhP0HQ7xSVHlN0HFEOiWx_mtGENg1.ZcHNI_KRiWTcXNLvEKlM3L22JUBVazivKYjJve9Pc7mJ3LN8V38koXDVg2mnzzZdRmMUEm3UGOeCG914PgvuyVegLbh0t3ZFEnuQtKpJ_ADyo3uwSF11HkMr1wo1LpqE0sNCMinuF8Z6C0UqAZvS6zMPFUteLWhdJ6nq.uYV_NtjttS07bcxQXLADg3_qJSQF_tPDpgJPSaCf0RyPPDGim2akoR7plygZywvEueZk0ub3Z5YgHu7uw2IBaqGuydIt2ZSlNTzsNnIeSkWTiCmvRLLAYC8Pj3hQMUAS3IBt_ZuzBksvgLWu7aiOkVHpp3uSJBT5yRuZRF3za.oMpo6UToMgHMEFUi7YwyPfaPytod_ud5CXJZD1N3MiD88Vg5fh8XaFy_g6H3l3VZZQN.tjQ8yxWKWGj58L6NX4d3MJa8P8xD5D9bJkOsGHvnzBHi.EOw__DPXHa2nLzYN98uLrBJiRU0BDv8lrIaTd4lCMG26hrWupem4A_E81q34l4Foh1izoo6o1P33SpuZOCt97Fl3G1_tebhekpXfiCqej0ryYsJHrvqjuadX1t1ZOnNKj_S87dpt_fC3XuKzjXus3cTwvviZFWrySnreByprSptr3IWvH_JtPUNKL.FgT8rnqrUcfODaEVn0o2yOtgT_aajMXS86ErxrGLSV9qoToOCpEmjj0B5t9prYtf0RRiKPM5ciWpm6cVyGw67OQh3Z"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=9134185c3abf3f4b';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, "\/10009448\/harvard?__cf_chl_rt_tk=fROsG1Wn.70sV7x5ogkt6wqk5uztSC5e_x.Dtf2Km_A-1739777668-1.0.1.1-NqrVfSmsH21AZge6U_RGvZJESNovpgAHakc5wtPaUsk" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>