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: '9134181c0b65fd83',cH: 'qfm42cVFO9d54xFbXgDyh3aSqZqYgxPpfHzVmWS2kv4-1739777658-1.2.1.1-3NqlW9wUWGBi5YZQNQHJ.u_3A3Ev5bdCWfMiA2PAB6GM0a8XjHUCbq8_X784VD7r',cUPMDTk: "\/17244\/harvard?__cf_chl_tk=Qu52VmYtNgBLCP38pRDe4tqK.0wWeHQzJigv5JhgaNM-1739777658-1.0.1.1-CsYPEmfv87rMvss7CPDUKFhWTKVM6KySOgwBp.JObpw",cFPWv: 'b',cITimeS: '1739777658',cTTimeMs: '1000',cMTimeMs: '120000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "",fa: "\/17244\/harvard?__cf_chl_f_tk=Qu52VmYtNgBLCP38pRDe4tqK.0wWeHQzJigv5JhgaNM-1739777658-1.0.1.1-CsYPEmfv87rMvss7CPDUKFhWTKVM6KySOgwBp.JObpw",md: "9HNn7rXYY5wA4jssY1gOIGvnM_mD_KAv5tGgUq39d8M-1739777658-1.2.1.1-QvEXz_AbsE7nEOEpwWQscgCn5K4DN6ABToZ1zjcxpGtfmuIayBqKBD3UcpQoLPrSHEhbp0L9cLpV0o51xffkBkYNBssAWFzH0F2I7sICVrtCB.1FdfbczzI8tuGV7yQ1FwsGGDxnwwsbCo22jCg_0TCMB7dn9JlZssas8OvLWvcikoWVnxzpNslHughqAIK2Qfb_iMMxwrrijF4opdLyd5hFycc_7kWDNZcqRAjV45lp5zzxohT5woh3bfoV59yIMR4x16Y__Mtm8wQ56v4lQvjBdJjhDTFWMoA4W59gwTBEXlUph2Zafbo1oMbMd3rg2wkgcO1PSs6RLnAVLaYgH3wPtXpR1um1VHJ68auRmFNM5oxk91zOm0KZsxnVQC.tCCBLWO52TshKA7o.STpf5Nrh.N8wnP8i.9gD0AKvKEAEODyxL.mw1j2rPsycBBoU20L6wutgoZMOW2C44EPag4LBnltDjLi0AaeqnNpxC8biJ1EYbwXS4roF7mkcCSdPdDy1hwfl8v2fOAhkqn3aIhCGQcYdYxJDs5EHL4bEBQOIzeE3aFhOf9_Vqyt0hG6WXp2KWs_bVuAo8nbcWbh_ims_Fsv79tXtGeHoK9dM1sFf3GscTzGz0YQBUnLlHZpyBm1R.C6N70OpXXXv7T6uOUr66UvdV8orzOmlSkypxpt2GhemxvWm3CgdX6xDG.XpbCjbovWEw7HP08ERQoehh50HPg5iY4SmKxA1s06yuFyLJqwK_1SJfHYX6jvVyPHadlHkgrrpHeXOMCqVGwb6.OegIEX.Z4gd3wsYudYcrR9mgByGH3YB7QoQ2ZyVgrm770EA6itb_DiF.7gu1njM253q_tZdBqu95.4J0KvvD7wnnqFkUPUpnqihti.FLCsEvgWLFrO2T1yCPC0tnxNWfsni9eQntDxli9L1LiKtlU6kA_VTZEwqPfmWxJQ5EMWFZOebl3_oJ8BmvFu3zYgOsKKTTQFpE03UuDEDNxFw_ZLFyEnxpX.VqY88UyBwHQoV5kxBs9lZow51a6.eQHHpR7OawPojjSBPkrb0Sh7PVxhrkeWjr59B08ElX62e8khaHvHz1PdNY2sfgxNiKsjDWXDA2NaDlund5KGivEs0UrCZs6fMgXAnqQXLE6lCgLqqIpVXIZh5YWtWBhifaXN1MdPNs_W8qQ3pvQYnkB6C2RfNwxjN_S8hlcFNysi8yBKaQi2XJIIaV8Ikx5iiEBm0Aq6z_QRDSEL5RB1UhOG8BPAx.Ta1XgzG8rdvis9EsrvAjZD5RCL6ZmUm0oPrCFnTG16B2yobAvXzhcrRjEtAM6Zp7QUmdDeYAVITS1hKZR_ZkTowzJGPrPcvtt9Sw_6LbEVP2Xum85vSEGjYaKmIeQ54Q4Wja9cheyBhRXIUZQlOchyCGX6zfzl2azY1PRfv01N7AtTNCUpolmOe1f1dUBC05QP8sxpuzKMZa7Om6ec0D2Ga6JwL_TF0_0bgq_Y60HNYVQz4NRuBIS2KtnqkqSLn.foGZhOw2dY6GvbUwado3TbHaNTN4t6tQIUqN75JcDjV9.MDxHbffVJxzTD6GkZHQ01yHExK8xy9ZcbyFE.Gmlq_15w1khoBn0hE.7YmtmZsEmaU464CNa9888ZcFW7toTMfxW6hcDb5ssTaXUNhfA.eW9eMv3t4m31wjFr6fpRR3gpwDcCE9qVkthirnIO63JwKADSw7gnqhzw_Za9JJx97a_gPP_VdujUmo.lyHgRLO95895vhEfZjjJzJhhggx_XSC.itkkbe97qAp51j4Hw.ozzldt1QU3QUToZrEfDEOSsCNAllLwKiiyZOqZwl96kot840exlYmmf58kB9Qz35FZd1vW799v1lvKbpxtygxJGhxRoLU83Ot4CWrJo",mdrd: "3xRn9mv8eZlvbTQVxOO4R.P14M.I9tt2EpCWTQ3fn5E-1739777658-1.2.1.1-LwlfR1oogWvNg5IQBwcjIGoRGy47_eHJkpmvCskl7zefPCDxQH7_tDeC07GQOo1gQ6GgLXu9f2FGzLraqKPJtKs5UEwaiOuy0ig47TzGK19RR00Szypb_UhzQ4lPSITHluPyvYLQ6OqCBNLhNS1WcSSTmVXzYTU2gFbAm6jhc37Th0MbUrghC7wEFgk_pbhmZvGYLPKho0yxuNJJxwKkYNkDlwn0ykgSykKw6iFqqt89bbYFPaz7S849b2ht3CczHYdhFVrohPpy3zDCNQzM.Gvw_aYcrk8y5nUBa.9pnYU9O.1DpKNtOFGXJALP1i6FR6TqsMD_MyaxQJ15mgcbdEmndFD3fbotSfeo6RwYKFmkQXHKQiwGsEJm5oZD3oLwi8bMKivfeDrJqBJE5nWvr7ClilkPnkdf8AziCykEYfoNEX.vemzT33HipRZF2Uu0hFwrOts8X5oWkeiOo_zR46oAhEhpBaHHwuadV2txzjJXApJMrWM1kQi5Enw1v7uGhiQdftEOhDXIGIhToBQHGDBMZjPfwzLH.A9JIskznaEXREdHZYcX5Jen_J74ncEIibOqDp.D3RwN9Ul.xbiiUY8Dq.q_7mr2N0dX_kJXypPysKORlyNem0cuqIissS76Rg.USlZj7MKojJWE3lcQSWlsWdHIdIU0LvRMCOb.HZ.QncCx18910r7k9bVD85CzUUAZJkzAYyl6iJ1iRf.wVK70o1Tu0uPXt.OGFEsjg7QAF5Rhrj5t8UqZWOv6.NL9I9miIVWNsgaSs2jy9wWMouEBGlvsNhYngZlzT.IgF0XXsWmL5U4vbFGL4_NrHY1AuLUi02qfUiijVE2ID3LQWgsXyAI9upTsTlqchkkikY84aIrupWEhVAG9csrLz3LlSiYfMCu5zxBbU48XQp.ZEiixqcES6F9Znk4iBguVnq03jkdBKSBg4IZMLwtb4U3RABk96jkkP5u49jIOs0LORgQMfeIr8Evr9JFwO9ngtMmJK3E4EQN5994HcntHGj3tqLaEM7nvhddZm.CjoQUIUluwBRxtrSAYhKQrGlVEQ23Yxmfu0EChWPR5vxPcQCGzViSprPQwekzY2s5cWjjFGviCPWjnl9y2rmfnPVhMG6xmF3in7pRnr4RB57vC_PcGy77F1ZjiUUhbMN9Umtew57jWjyA4FZSYCDjeAf2.gt2OBMVxqrUEG3nn6bxRS0uwQrZ701RwQfgg_hfnxjGTJM6Xp6wCFK1gv_HEuCkhWQv45i5T8.hQ5NP5oaeWDLMspZta35BGy_Rq3oZbIPYa4S0QPqqWF_otF8HQ6KuxNdXz5FJIK_kFv1vwKJHdo6_XnA0JpZs9y2Ndla2cCdi9LvuWYmKFL4yZObDpMC.z_HE0yRTjKsClhoqXHPhd9qzFXR.9JKJDLfvtAUk_4XhkCccqNCcRZmtSXf1MREi8ZajViRzc26Hhus73utNVZzJiX8pHbXGB2_BccU0alBn7gxIeLgXEqNPka19RSzdyU0ZHBoXhcIYdrgYw_x7J9TdU5FUOBTsdb.Gxc.h3VY8TW0CN3DcjKg1ovNu1FonaFmfu2UcpFK467Ce2JKdjnkjg7KUo_fTuovrNC4EiHTZpv.uyAG9dE2OSTMMfVeAlkkLx8LF8jTGlYG1CiPF8jTzT5UL9Vrnh9sDHML2TI1rbHl6Q0Zkh1xnlNA4cbekx_tCnfZtDxltONOl7CIgozlnVwa4dw2Ab43Xh63upEvWiZ8doZ4Aivqg6WunGOwoulCh21WPpML1Agb_f9iZTIlWDcrEqGieUFYxXohQc1mHQ7RXiJ_sKT.8h7U87bg2.a4a9Aya60vMx_Xsp2VBPJmr8KAeZOpa1YMouxVW3EO7PvU5MtkhrIhlJae_CIJIz5cEgHoF2t2PiFkkImhbj5E1dlP_M7fYpu1iEjZMt3WP6nbCJlRamr1OmFcXcueMZD5wMCkt5kRfXtF8HtWDzWpvt"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=9134181c0b65fd83';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, "\/17244\/harvard?__cf_chl_rt_tk=Qu52VmYtNgBLCP38pRDe4tqK.0wWeHQzJigv5JhgaNM-1739777658-1.0.1.1-CsYPEmfv87rMvss7CPDUKFhWTKVM6KySOgwBp.JObpw" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>