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: '9136da34295ffe1d',cH: 'a3cgOUBHJ__vRuz9AQHZPGyKuom6dfhmOnrRBkBsrWc-1739806579-1.2.1.1-0X5ad96f36NaPAz_nl1rMPrgizM6R5FtYMHY8l_BWN.q0ESAeuG6x.0DUmFj2syT',cUPMDTk: "\/7857\/harvard?__cf_chl_tk=6vZdGzjvohSqK1Jx3yV_avrFYmijRDpdcq029h6z0VA-1739806579-1.0.1.1-.yy5SSOq1Q0Uu52UkHhyXC3oYpWezaM9Mcx5d1SGMfQ",cFPWv: 'b',cITimeS: '1739806579',cTTimeMs: '1000',cMTimeMs: '120000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "",fa: "\/7857\/harvard?__cf_chl_f_tk=6vZdGzjvohSqK1Jx3yV_avrFYmijRDpdcq029h6z0VA-1739806579-1.0.1.1-.yy5SSOq1Q0Uu52UkHhyXC3oYpWezaM9Mcx5d1SGMfQ",md: "9Cxo_f_LNVBrYvBkBCQTlh7Kan0BGC9ITT9FGubVgOI-1739806579-1.2.1.1-dvNP0npsVbUWYx4Y_Q1E_z1OYDD7Y7Iye5phinbIR0GDxTkPpZPWMuc8Hshmuj0BcQBNNnZl16U6k.rsDdQYmWB6pDnZ8r4CLnyeKvVvBpGX50xTYCrTf5vYTnjEAC1O27d3FaqvpCOscK_4kWYK2xi5ba8pdP7Up8PpgNpplIJ7zu.QE71lGv8G0BUc1BVN7OTpOjbUxRqn5A3AG8EO0cvp9C9sgaJOxFVMPRRMGRkBsvAoTnzn.c2oOgA4qNjzQV.orgCC2BJ5.oq0BdJVbusFu_GONHiaput5Xs05hKdreLuYcy4esoKf_cP1vIDo1TIK.vhM83s2nDVKLKksR7SLxz5yvOEP9xjToORDc8PmABDbfs97wEuiTWfspzEqb9spT0SCA8VxMU4S6oTk2qYSZvBquFy3q_KD2qSF..r7UFAIcsO8KUuFwoxP9qWlJ4glKSTUgQVbKJwSnm4pXgk7IZEY604tWk8BK_aHpa.T3k3rY9RjepnnGi41cp9qu5Z2MSICL_4Zlv34h08LflPax0puVkt8bCBB5V.9CY_NqgFeIYeiw7.uXv.bNJeIvmkkI9lVpcj74rAWrYdG0UwtvfQwOEZWsbtHVgEoDpsrizlvKWwV1HfyWgO1oNaqqSelnOaa0LtJi1DrWqjSecnHasxOeoN80SaBOgfGDfQpIRo.ooyxESetcf6t1QUq3_pd_EQIYtN6c5iys5v9zAKdqMxSd.JAtkcdAZTQN9e4qkpU9egRNBORtJ63aVqzizICf2XEAcHLly3h79rLfLypMw8_qJ4dlO4fmzcZuZ7K3ND6RbpBQXBzBwxqsw67Yenw80M0uebUSqDzMmtzlJZmtH_U8YxNTwHjoDx0zv6LhySgpoUe7YjU8THvwjB4nslCHzIQbLuMkpAdermOiMEHkmnlX_prIcJHU6LswNmNSIY3K4YHA..2i05j3Uo3jnrwupwoU7kMdo6ad5SP1eXQJRPlEQqibNLgRltFSvwtOxcOJAbq.yww52psfnrr9VpWUeg97X.bQ82nWYY0HFP20xCXS_kU2xIhAOhUZe5Y8bZ3cZm7q.FtgsmgUWtvSnZO2ORJys1W8uPf_cJUuGwNvqfvhortQQOhAUE8fQWde1H4OXLtY.cj6VqOMRff5UOskz.y0orCU0arKdIK.wvf24UcGdlqpAI3jMpybLajFArMkCOrkwUDTNDWghNeePMr9ILN_VtqtKH2ZeYQDARZEp_1OPmE9vy4OkaSG4wfUiKTUwR4V8OpThN8_LWgb7dhNFsKwajj.y5GzGl4CZwk4djYO_AAxw233HuyJFNJ2Vl4JOiyEuC1gMO2NZP03zrwwgvIX367QisKjE.BE30fzlouz_lNC1043tkbDGGI7rYuLHWL0RTf8kdwCLCK.km9oeKo7cfPd1zmkWRHw2t5O8TTH4x2dSp9xpMxMRfwOAZF907zRrxN12ayoJbYi5VCDDIEm1ntqQ.ik0EAqNEoXlFxVGltIEYzx3P7rMz8OtZcqv446KKiqSSR6FzaZ5iZrYTfJ3qkVpBeihxsCOLlnBzl6FIOF0vgmUYqJ2OwgDLASaYxXGY5ESaxXnqWyOf.ZzYIfjPa.77FUO5x9kM4.C6RndbVc3WgCb7E4nBpMC5XEq3Ebf2g0q56L9zT0o035adRYDpP7Belr3jOqodzocDf8dD1RgqFWriUVcqkAXpGH5gEQaqiqmE2AnKPKwSeaXiecTCOLmweAXTek27igRGln6z_7HANxpN3BNe4UeQEWjOcMtZaEY8Hx8cl35Dtx60VZ9WWkbIxBUA2i.fy0kt0juat.WgLNbxjoY8IDfit.wYLk2e7l6PjVI1xBF7yuOHz2UGNdJjnzNKCoZhRM6XnCNIdXSAwcoo6Nz8",mdrd: "KZap6ftaggtzY8qSIJwNhDeE2dw4dFfUsoLfCnDm5jU-1739806579-1.2.1.1-tuy685vRxZO86ONt6nmOLmcDWKO9N1Iegsny_A5vaoosin1dsskB.MWQhQYq7A59EDxZP7PNo5X6J_Aa6Uh9PVNHFhkmeaQgZNr.bho49Ws6oa8fjGrG6kViwGNUkGHQqckbBCjamvE3DePxM0cgl.tYpR.neL3tm1wYodB5oI4j4rWqhVfmghLFo2lDOtjSqt7A_3q1YZC9MtQTsp5ONnGn2jmGwQYimEApaAKWTXJ9GF6paaEZAOuXg4WsgcGR13PfvmVrxYDghUgdlbVKvcNxJffJHmU.fX8SvXoi1XhYd5V8Et8s.nkt5.XpOtiKhbZE_Nf8n.Y668hKJh6UKYqs4gPvv5uHnL8e9nubJi3KHYnf6_ViTfnpe0RQyQG7mTmtqd35ElKgfg3p0EmRlT56red7gAvH35cPNM7ph4rW2WnYE_dulgmfVJ_wHGjOG1jSu9b.Zk0fDs76bl8vw0u7yxhwB9AGc0SPks_njR4tZOfpq_YM99hnHFsgQpAmaZItjRL6FKmWYrtsKGvlmNgH0VnCbJW0CZ4H.63HJ_q48IVvwjVzttOgm7FeXTx4r0ESeRsNSHfp.ihUAImQ2scbP9WNO61O4jidZWCstg59HIwljp8ys11Z_xWKXT56tniDGDlz.EeQv0Cw8T2URBNskVM.W53w_UYSad.H7PdYWXz8bINntj9frTfssmXij26_g.KedgjvS91DODPqMldilGVT6VPHY38QVODHDuI_1g4HCD1sVJV2.qyaB_4lUcx3GYvq1Zs_fwtBtrmzX6eJ9h2zeFAjeCbp8SRYDQ7xWVNRArWM9e64TsOzNHu1m6wkjSO4DWfxi54w84o_2RPE9NQfBGKpvQ1DQPIoz0nnL9HqFi2fC7bPw7b0cEaNTqUT77.pAoCAcDZFzOvaYLbNl1s3vvicQgCU0w5mm1LET6GWCjCf5a4JWRkgR0RmU.AbnOsmIyCj3MMW_Wwsp.VuT3CuGO8BfL6U9j7kTbpPDqYtJgVazMsXm4vfWDN_EhmAqnYK_VRelneLJ..zDo7QA7RACk9Q2EOSAGH7WuR40x.mY13W2iuD6h2gxe5zme1ADZJqZq0GcEawm3pVUWJ2JoOhK8c7m1VHBpv3n32xSwG7YDHFZsV3dAfqR8rfH7Tgr5YSBMHWlExw3nJ0.7ot.8N_QJ_QlNopK3yvbDMQC3lRhRfNAgPzgtT_M8QUAgB7RSQ.RZmTvSOYjfGiPnTJPgX0CiqZ4As7uBDuS5Z35ZY26nvtIPja6YRwDbWPEv71CJfym6ptuOnrQG6hw88NI5NH4jS72BlyPLTitvjf1Qn3Ay8vXJGnm5TR.p0gWrY8ZVDicHX29at.LRiEBexveWbLtHKspr.DwO.53cWRLVm5OsN7OaD3imw0K7JHV0NTqPQNF5MqQ1p3mWfnQjP20.rQAZeGv.hbIwOE0QxGBFD6WkhQL1VQK6iV4aiyhSFilBhrXDPlJnlqBssVA.u0O0q6lylqaaxXzWSC2jc_VDe9qNIo9EJYGvAKj3mza9ByI2jFPG1h.gSXRv6XqSHHPqUlslwxgGGgFPfsw7JIDcPuBNvxSTozUaM2dndCHDRU7xwaICVt8eyySOPkWOm_bkm2G_VHyB6hCQV1QH9sC9WgwmdQ5UQ5LAa2svd9alrd6hVu4VBb17bOphQpTiaDCBfwf4qwC.AROah_kUFI0KDUu12a8YzE.ZcRpHu9wM7DDxnge.YEWurOuqifH49ZMDohl3mwhB4y_WTRO6Sm._LZLU.o1yfpBes7_2exlFXUH2GQUrVlkXjIEFhc4S107rm2KKxaZcu9PiZhMmFGx9NFMLcJnSgy5kODkV8DDbw9xZ_xu1ZBfXMWlH.1M7x1IStu3b_E.mUFoQFAU0Wqk28LktGIbFdjHESCACx.Ll3nARUpwAUrznqJH0hKqLmKo3F5JUS45EOJfG3k3NccHLvqV9evrZqnwGxf5Q7m"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=9136da34295ffe1d';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, "\/7857\/harvard?__cf_chl_rt_tk=6vZdGzjvohSqK1Jx3yV_avrFYmijRDpdcq029h6z0VA-1739806579-1.0.1.1-.yy5SSOq1Q0Uu52UkHhyXC3oYpWezaM9Mcx5d1SGMfQ" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>