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,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHdpZHRoPSIzMiIgaGVpZ2h0PSIzMiIgZmlsbD0ibm9uZSI+PHBhdGggZmlsbD0iI0IyMEYwMyIgZD0iTTE2IDNhMTMgMTMgMCAxIDAgMTMgMTNBMTMuMDE1IDEzLjAxNSAwIDAgMCAxNiAzbTAgMjRhMTEgMTEgMCAxIDEgMTEtMTEgMTEuMDEgMTEuMDEgMCAwIDEtMTEgMTEiLz48cGF0aCBmaWxsPSIjQjIwRjAzIiBkPSJNMTcuMDM4IDE4LjYxNUgxNC44N0wxNC41NjMgOS41aDIuNzgzem0tMS4wODQgMS40MjdxLjY2IDAgMS4wNTcuMzg4LjQwNy4zODkuNDA3Ljk5NCAwIC41OTYtLjQwNy45ODQtLjM5Ny4zOS0xLjA1Ny4zODktLjY1IDAtMS4wNTYtLjM4OS0uMzk4LS4zODktLjM5OC0uOTg0IDAtLjU5Ny4zOTgtLjk4NS40MDYtLjM5NyAxLjA1Ni0uMzk3Ii8+PC9zdmc+);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: '914a563a6e75f8d0',cH: 'wbth7tC7wO8KR9bNS7YXf.j4G8v8TqSDy8EuqdqMFog-1740010889-1.2.1.1-wjISRQKi.zhuzeBBKmC2qTFlAVGXEfoPbzt2Fo0fK4PDJwJ0nav9deavC.lx9cHX',cUPMDTk: "\/9997899\/harvard?__cf_chl_tk=jTD.V86wU6ujUI7ObMPmt8eC6SvxUOyG73N72WvoC88-1740010889-1.0.1.1-MZIJLXrqWTxP19y46WFRerX_Q9lHr_RqF7myRWkJQPA",cFPWv: 'g',cITimeS: '1740010889',cTTimeMs: '1000',cMTimeMs: '120000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported-browser",fa: "\/9997899\/harvard?__cf_chl_f_tk=jTD.V86wU6ujUI7ObMPmt8eC6SvxUOyG73N72WvoC88-1740010889-1.0.1.1-MZIJLXrqWTxP19y46WFRerX_Q9lHr_RqF7myRWkJQPA",md: "ov2PLLji78ifEj8N2cKmW_Vak74EEgIbVWSeERwgYCE-1740010889-1.2.1.1-BKbGnr9LmYJeEtM2YAdp06kohjtlRRN66tUNin0EqbzPdP0H.Dxg9yY8GWcXR_WllojuCjH8CspKMEbvL2v1a2D6SV8nTT9zOkXILuarlClzSWpxqzu1f5R._tV7XGkU6TPDGNy1qpGU0VLS1UUF3tnA0_kZ8MAx7GzZx_SQ8DYm.0Hjs9KmyuoUCWx7lm.nPoY2UxOL2p1XrWbpE_HP9_zcenCIzXaJOg.c1FXAvDOGajrz_4S9TaqUf.a2AVFezHMhTlFnnkZrg97nKmOUuGfeCCUszy0ucliu6P7OsUmxz8pWfsiCGCdarhmMK90HNiI8KGYpNHpqs3iNNptKUfk3fRn6pqg577ob9GQ5qJnEm4.PsoDRwbbdSTO4EYkGFhhuc8VNkW6TmIiIMy2G1JOjqTOvZ_AMAJ.jNE4_OehSq8z5zKf9xLkcfF9.yIeSeFkhwme0YvQIsLkkf._TOrLp1zoBH1uQbJaZQb1UGSZZVAe45FYv5ODpzx.F4fugl4QO9prVtDI0bkzwn7Mfa9Oe1fm2rU.pOCvB94p42WwIJmgd1R3kgEx4_u9IMP0Vcujv.753EcMofUy04WFLsqwVI5vJCqeeGoEgVHGwSIbqnP92R_5ZVlFb_libyaP1Q2l3VDgv7qpiQEtQyIVo33dBbR.xhVJn8v2SHgUICLrWjXbadQsM.7ATI0LRkNC2BNZPP1ub_DufazmXSwW1QKtEqKlIBa_HichoVqX58s9bev5hM2EBROo_JbXJWdXbiB7I7pjy.yWCXWl6PPJ14BwqAXAr37wI322iZ8vZAHKpCWldMITNvyKMvKbnx1c4fsRgW1mLzhOiC4jMK.RTv4RYGmByNDVYG7O3H6rfTpcICSYkTnuFIkukd7k6TI.5yGvxMD97DDof3SmLW5ztqBuutLvzgqXki8rTjr.gjEwCkgU7sN3HeQX6DlkJAVrV.xcA9yb.FNf6wFElqE1DLGJE5II5EqNamHnuX9CnJHGKJAsx.e5yQF0fPgEJj1h1TavATWumLyYLJsu3VnpwzfSPWfvgIh19aJBp34scFQ8s_WrYbUECBvmHThLfeLOe4MvpJlUgvhvkc0oyYUCaVAMHg8Ke6j0GuvdQtRgaKeK2xxEBdn_sI5IHVilGETx.pWvLzfOEapdzHBxpDPKcgY.GpmU_Ba7bq8gBj_dAVNWthovKhrgcgWIG3lIaXlzcMcANxwT._1g1PQMFxpgbde_i6ultVDDn4sp45FXH97xROzLSAIiqEa7tDpVz00sVnU4dziC4EbNUAQxj1lujfcMGaO_tSEsz6Ak2eh3JuIMIGnTL9xGjsrqwQvvutnWxlhy1sBJtysZLxFiwnV47x24L3DpovcoM5ZcrILDjADT72FPfFY8dvVzogsmnSjYh9ZgGj42k2w5MdEBVXaBGuDRIOGgTwQiJnVpe_BDkajwGJfLTZosAZe4TidiSUu4XVFp7MVt1cI8Jf1Q35a3317Jb5SfMQGABmXRlBTFGWUfhmb0sfstGyPRdEeFUioujYZsgB3YAjTcz.1yXlV.ZhDfN8LQNgy5_tgpLk7utuOwPIrxuCkwtX3Ha1Tj0ORV.SCjxeD_PL94K2OxcjWpi3mdhvTSgg4Rw.hpAoWkVfzI_fwaOf3Wgfg1OgOuSRn1L9nwA_NJn3ECe8S4q3S1YjtHKdCiNnF_i3Eeht5xCwzxbALZqhQ_HM2DkrRJ.NIaXosP.VOjKiwx4sxF4qE6o7_nhCkl5QnpFwwMMQSz08fQTFGh6KK9BmyPaf68R8zIqUE6uGmx5QTLh.16Ux8nM5mwSrKnNDSmfuKDwSU6PT8l_fSBdJKQOyWfLK4jYd.cIBaR8wQDoWwW_gLm.WZea6uiAZhzYOlVd2R58qzYMV9Q",mdrd: "JQ2ejuS8_s2wr_ot_yW3jRwD2mfPN06Aarolqa6DLzk-1740010889-1.2.1.1-t7jfShx8Nj_NgBCCZgSV7wJCDy.40rpICwBKQNWpmc2oMOMvGs1h4qUAAQNr3e8Iaxr8_hX04zmGHuHpCgwvfwhZBZ6x5s3MCqG9vquh5Gnv1KARsLYw4vG4YnsUayDMj_E4b8g2X8qeS6J5gFQhyDe8AB1NRctzDs7zpgW.R4gUYPbaFWJsom_TZmItRWitumy_XX8hgmcrplQcRqqttE9TmkzE11jV.CwwG7b.KQNS1M0cCxFjT4faDJkPKRDPpR7Q4Jt4pBcc_2mKJzYaWU1eQE8Pbsa7FMAg.vXAjSBx6WG4cJGlVAyw33YCVw5SHFCVw9lQEhofDKe2Ed19xircM0lgqDymi1EteJ9ernR6I3X_FSQbTjz6SavdvmONS.LwDyIiJOs8NBsdzlO2fL3wA9ZfFRMSXN.fBefjE10JNANi2uTnpgNUTh47ClfnLjAJ4.hI9cVrjWaUrpQGU1fas3MjMClZS4amFaPjaKEAwa39BycSARV0LFRwz8jEba11ZEgTKA.N8a8zW6nQQ02cQoZ2lXH.jQHPGG7CtZfcBK9dEesRgvBx6yAj74CxalY5h_AOqoBp7XmuCZEJrcA9whHlqoGn7.YysmDyMfd_An97qgt.22_FT7Gv23imicyjWLRn6UPreocGY.V_nTXNuwU7wZTkYfAPikL0GrRwYDDQCH5dHOV4xiQjm7DuuFR24DCkuRJkDUUR9eIkOKIzJrwFi0T3XMDpoSRgo8.XMFBZhflyMeODsrlHV1ZUX7J.6AeubfLn_yhc4EpjOPUJKM7I8TwdNwFez.XiGYvmMa7bDVlLGiN.gW3cQbprWF8_yO22csv4hd.j4InygEA18tW7pn59D2n.FCNfKUBPqLBToquPije2Tz0YtfhfJIomn0dnM0E8BVOWRlr15MHsnO3oQMqJXVpsLgNzlbIsDO9u.vUztwQHp.Tjsu7w5gRjk1_96dPLOG7pLMatGU_u.zlWbAqtL_8Jgev2lCJrRJ2Do9wgp..h54.qg30x09HQeGmn4mK25zg_6sry1estG.W.VORzbYoNSMDz0cy12bU51CXmL71irhbnJgHj_Mck1sKsGKCbCWhRxWn5IlQK0yme.BEluVNdWUgtJxg2tESLlR85s_08BVAqMGtaGeRiu0zhOG2FEPv_vPn9V6G2ls6gF0YN_7unK_0flMoX20U5V7OseklxVGujqoxBLMFhYtSLtCxcAEUTjSA1xE7Pw02ApNAtg6oX3q669PgXVJUNPJ9q_71LvDAjADp8M0crxrrJwVEf6Q8vJVvLHDc6wacN7tluWv9driUiK.oqq0o8sx2hv2irwcEK2WhUl_OZlNnwqcXHjevKw5_kjjoBLn6O8gwEVbs6MEI4WBjAuiL0NBv4RWJRBuU.0J02gXI8kquD8fHbUP7fh43WS1V.KAg8DZ3o2A.PJ1.C9Ew6But5p5nSX9sK3D7sZGwf1shhtn35jHVtJ_UxbgVGxa4QGaCZ1tNkLNjpwOucdG.JSYRJuBanfwjpfdeT1nyocmi.wdEnMUhHcfflzpEwFwCWVyfoMUHIuVCayFTlS.7WBWdhqK1BKevX1IhoR6DqjuBbhXJmWmZEPSvgqBtsggI0u6xdqpGE2pINg4AzhEMGRnV4I3Fry3kr8_gsP1BQzpeKvqHwChGc0vJi8V7T.Fg4dxSBtNWL4oVW2m.VcYmK9vlqJlVulFok0TAs.Asjs3xURHIz2wrvajR6Tth.7Kdp0lzu4R33nL24qO.6m9eNF2LMMk6Q8uLmV1LND3qTUGwk2OH4HgOBuY7Iie_hUXrmW3BvDNJHM2E4ILkKbEzQmeMzu1M4DneDJ3Nh.F6ddlLfwPdEzRy29a.c6Rq3_tGyPk.7OLeVS87LKZoWwNxzNIiFo11L0.OePIOYUqt0_tIffp60_PhXxhgYcomWcGcRecF82bdfCD1.AcAbdzkTtddPf9P4XKAfHNR0ljyZA7Ix4V7A67EmuxxxxtdZXg"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/g/orchestrate/chl_page/v1?ray=914a563a6e75f8d0';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, "\/9997899\/harvard?__cf_chl_rt_tk=jTD.V86wU6ujUI7ObMPmt8eC6SvxUOyG73N72WvoC88-1740010889-1.0.1.1-MZIJLXrqWTxP19y46WFRerX_Q9lHr_RqF7myRWkJQPA" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>