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: '9135f4cd6d2cfd7f',cH: 'elivRtAjdw1q.K1V0JiQop2AEdImpSCdvY680LUvJ3o-1739797183-1.2.1.1-6FVKrt..WxrsqfkBES8n9vyMetTtqMkTIGYXqMfm9Jj3m41zAOCTpO1a5X5g__vR',cUPMDTk: "\/3407\/harvard?__cf_chl_tk=pVOoa8.rMGLlTBW4dwQJ6UFvAgGrJF0y6AHKitVQMfE-1739797183-1.0.1.1-BzVIV__d1azHEG5rzwf0XONMmHzoc9JeJhcoV0K7bW8",cFPWv: 'b',cITimeS: '1739797183',cTTimeMs: '1000',cMTimeMs: '120000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "",fa: "\/3407\/harvard?__cf_chl_f_tk=pVOoa8.rMGLlTBW4dwQJ6UFvAgGrJF0y6AHKitVQMfE-1739797183-1.0.1.1-BzVIV__d1azHEG5rzwf0XONMmHzoc9JeJhcoV0K7bW8",md: "9.1PQ48pds96yikMNXz51fNHfnbM5em8CGAGYB9tkos-1739797183-1.2.1.1-EQleMvDy1FmcAyIwGIouYwxgFwPPbDLwBYBoiPFCAwJWQbpuIbPSOByqTsoLIEdg8wxj3Tkm0NrlSfcngTxuFKS1ocaI1G1NHCMvs3hvanr2eBaIk1SjepMfIvuOiVGPMGgR2h563BriAYCqgJaXVP8.Ci418ULqpbqgXuiFmc7lcGsqp52USZ9NwQVv.tk.3gaFv.nKaRnAz3daHBNDUNx2oiHBOoD7zGXP.K2nLGj57mJ8rvV.wrQwFfrPHNM4BTJNMa6sItmSzHDB0MDEp9bsC9GIHrxtw1qrR5x7m1LFK8kM6.hG8_PwZgKOAergssBWY8NebD8qs5.LPGojyYa3iCTCsKtM_wY4oGR5urjfipNHtoxUp7pp9Vl.T5prjiyCRn6XcYK_AlOvZA6WdQezojIavbbxbeu6cJH7hCQ2t3_PMExHeiWbahQ7IPmhReSgG9ep1pJVFeVA_DTX9NFrt2BYcYMd90.F3TMhGrnM7tG_HdTM8pDzghpsA28p0X4Z34bCf0wnMlhYNCG1BjLwPOwgHRgTcbV7rAvQ2f.PPJrTLjck0Gn693HqMh7NbJmXnFfJYkwmfXgq7CinStjpdTSlvjTknUygd1jpJoqc4WcVAxUT0v7EuaJF.iumhVSBkqY8UE3JSs29uOpT6j0lwZ4on2TNILrAWvxJTyxMHMoGqmyb4odJfTVXN5EVjaSf9fwTn0W2TsY2KXsb2qj1FT_xBIQngJiLx8hNnuVcXISTDpjSLD14pSm5kc7XDVhUluLVprHZ7pL4kmfBiRNPSMrFh1vgRhUSkMYQldDNQsJsHGevE0puTnGgzbZDN84pK5S24B0g0qKRHi30nQ5g5ImakyN1wt608PnK3FiGFaydlf0L8H7WVveHLio0_ENcfvn54h1q4u4ofNwT57yuohoTkDvyrrmE4AHKoIn74_liZhZz7grGGyuhiv4ZGsmd2C1VXQMgE6yYJn2mPZd1ZcfDmYUUSpsxGt9AGdQxk9zwx8YyksfAGXpgPGsGQyxjns17LPPUX5aHHHFZY6vtX5cMVFd3mlj5mX16IR.G0ufwAISTpD2iGS6b86pInREUvi9riklJh5B.2IctE9hKh2hDutPi.dlLpy5d_2mUB5glojqTQHJCCtya7lcK8HCWprIWzPVfLELXRZkno0MoRnWjgRYyQH6w0wbyBqh7.UeDUrcClO9VRcjMq0CfE171QU43Vy5Wj4egmvmONpgV27WHh5GUM5Xtlthu04wdQBTpdSkSBNWlCtKjt4mh5pFZW0GWe0JkBqDoQ_lMZkfCjJAsA8hAj3B3NcLlEC9MyxNq7_1Ej_syvw.B9iSsy4BSQYa4hAISeDq3XlnRnOu.XqNw8eEM8ba.vOArqCf8okE4w95uKRr85dd6ALk3a_S6dVB7he1hP0ldHzrbTQyhkbzUL8_3jEKG8LsmtpIpiDXpj1mTEd4HVl7w7QHPgAICmtqjMPd8h0Y7oB9noZFKGanN5KtPqW9jky6L2VNA6tj1Puit.BAJZOIXX32DvAn.8xD_ha4KfHcno1FxMrffkAekQzU3T5u7nmy8qrbQr5T9sQuaIuwJ9xnvfcDhgfyqHuS58yzF4D4.9K__tHQ9XU98pcZdwojWxC.z5MghGvA7pqvuXLmdRXSg5hKWTj_lZxvxDwxAaCl7b4vj5.r2bWp29l361DCF3Fs2nYWGg9srNyuRVzWoG7EAfzj3QlwRGJSmKGVLvsmnqNirc7WfzVzcwtLwoDWyhae73TrOXh0ANeIi.KoJn0GSbAjlNC7hmJgb0FPSxHa2FCQX50EAZ67DMltfedA2AxKaScVbm9y1Lyr2k0m3XR2ZN62sK._N3ykOyItBXXT2uP98PEzv1MvWGb7tmAtoA_wzR3M",mdrd: "9.dYjw.QGB07ZrXITGXiyGavYFIztEJlauocJCYwNx4-1739797183-1.2.1.1-gzakv6uX0404qVyOA1_RbktAkEbyc_n2dHnBoz1Q04XSm9O_zMdaXJXWry7JWrnVM8u_rpi.Si4PQymhEx_FCQi2hUm3wZIBAwQyvCmuxjSgTKnxi_9Yks4MUF9T14yvDEchoVqFzBsnunm3yclN97AqsraHlItNZvddMZTVIhikMJHR_oLx4Dvo0VM.ks6aIFwppKXHi_jdzZVL7JJQEyBmOJF7FXyZm.UqPXIaCZ9hpCYcrz4h7Ze49VkjxclIwGcx3Bi0XOxOr4URCXI4iKfVSAEn92cdKbKi5ztpy8MRKYOv7O3AdZ6HXf9wuI8Dq0bQL0VpVIuWDgzC234i58p_IMbu3tdljnvjbP.JcwafOTAZos9GLDIkJwFn.8JeOcy0RW2suYV0AJ7KGhFcZQ.SqNY77aq2hd5VhKx88QCaAfnnT.rvKphE0WW.SyZyoXnQ7blNZ7fIIZwz2RLPyN153JaI0ZgPvMEwFiDRtFO2tKrvBJ8C3TD1g55srGb8jqMunI6NNuxcXdk5VC4NSZPultM2Q63Bki9XIrpVersK5AiWhHaqj8ZzwdszebeHmMJF.uok3fOigBTO0M4RRG79_UQKgO6E2dX6VDE9wYFk6aeGt4Z.d5LqLrRipx86_7MH9AjQKuLfm5Z5x6x6pd2kNPTpRzkKhqa5ZYH9r1zzNo5Z6aCzKeJpEmeF.EfiSu2Rqh1oaYoq_ybqtJv1I_LLcM24HC6NaxtP0z0DsvKWV_2tmoQnlRMzVeJDpL1FIit.bQK2QDbpimDg3fVlwnNUzFMFboVX59TzYipHfo0Rg.bh7.2.H8jitXc4WF4102jsOjZ3iys.JHVtFWceAU2Qdeq3PHdrt59ZVn1xf1wbz9wOzuJqEimYOptsJo0jeduH98m9OOumzL4BTCVTrzBlxMYlVa12sX3MoVSRpbzZRQp6_yywkXY.RnJc57QM6M2D9EFPad6Lt8p1auXN.2qsuBdM9UmHi6JYc_PHi2DqWxCJ5Rp81LqFbCcZ9x441nQTB7R6r6T5UzR2nGWsLOFIovOp9tXgOrlrojonp7gM_QL1O6EnFt9Z5S_QGIlaggZFjUAyY92wGnIwdjPI8OuCjLO23N6Iy_Jr_beSWaj21XXEbatkKm_C2U6yH.p4Y9XjnG42ODiqdYNC.xfNKYERn4u7VKxyinXvolSCF3gC4.irsrZOK9eafPDYfAWw80tmaXMpQAvVc0WvdSzno.rM1Q.b_trpLl0t55kjrO.u8IBcr9pskdd47ax5m_kGRIhz6zWAFvbr3XridjywM8dKVyYdeZSIb0ZWuY6_txjbK7CEM2i943aEAcNRTELZ7gJl6nVXU3JgxViCSMoyRUUJWpNNaO7RE1jjl.U1lLOqSQFVlxEtAPVXKoUnBSIWhW8g6QOkVNijIxKa00EFr5ERGV33VKRRsYhlDlEMQg_NSrBv62EjNCUajVTbx9XDg5fBc_kf5V4X8JJ1DUNA6nbnDVUDBX6ZnJw5mtiM0rkZ9AXUftG6OXkNE81mIIHqy.gaK5riYcpwMgXfED10LAmjBTZfrERLWFZ_Be6NkcH7xG8Naj9RnFkIpYDm.AeqXc5NvYdgBBc2arpzmiaNEaszXfa._Uqq_PeBTfNv6NZPZ6UZTIDOZYvvzg4AKziEEbGiw4OBDXaUcUuV4sUZ1eE5x45jWSdgtqxm3vqb9x2Gt5.4hwQco1pmjNaTQWqc1LB5VihfIPMhOMjC9br5zEtCn7eQQO9J0tLuebq44fQGNNoPicffTagRkcX5uGotruUutYGZR0ZaDPTRzbkpL8mT7TUfpWSABJH01z2dx86udWYPEKBszCniIxO5bgsZ3IyhDp2r1Jv0JquuH6UTfqpys5j4F04KTxKIYpVGXR0EiPewcOKAMIfnM7IXCnWab8IFZd60eFdruhOf_Fh92kXRoKYvgZwsYAoWKFSDPXA6o6qT8M2DZNzgg5gfm4qq"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=9135f4cd6d2cfd7f';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, "\/3407\/harvard?__cf_chl_rt_tk=pVOoa8.rMGLlTBW4dwQJ6UFvAgGrJF0y6AHKitVQMfE-1739797183-1.0.1.1-BzVIV__d1azHEG5rzwf0XONMmHzoc9JeJhcoV0K7bW8" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>