CINXE.COM

<!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: '91356b8f4aecf914',cH: 'pHQwi4fggMAiBPWkBRnP3cfxTCDUHk3QlsSy1U3l8Zk-1739791562-1.2.1.1-fY9kVtisbxBeEo9RfEKVmOc_kploZ12P8WcWe12GNRiDFBKVPYgTii.dPV9oOEdL',cUPMDTk: "\/search?q=P.K.&__cf_chl_tk=YUNVgpC_Lb61CMMvq8FD3Gr_7b5_btOb0hsNyruzsDw-1739791562-1.0.1.1-GosTvseM1QfLInPRQpmh.9t5kQG.cGQ3Q4wHZ54hFuA",cFPWv: 'b',cITimeS: '1739791562',cTTimeMs: '1000',cMTimeMs: '120000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "",fa: "\/search?q=P.K.&__cf_chl_f_tk=YUNVgpC_Lb61CMMvq8FD3Gr_7b5_btOb0hsNyruzsDw-1739791562-1.0.1.1-GosTvseM1QfLInPRQpmh.9t5kQG.cGQ3Q4wHZ54hFuA",md: "mUKvP5DmJgpPs4Jk.5i34LGWSL1d6JJaLmlV5_4XpqE-1739791562-1.2.1.1-TjO421gGXZBAxKPp5KfO.s9n5bqHdGUYdfEXBREkq1GKh.fPX.vpw_lOdQqfQ4rOEcowctxqLn_cP9tbbNbhZF7f7ldhUMn4WgO7wqcY3ROBy4049IXx2Qt30QAmFrTCqm8Tsm0yvpkfjkKnAQctUKsjZhJkiszGK0gCJteScbGe.yFmzrZRZcYQtuOnvxP02ItOQs5zxtchVbVI_Mok8T8Z4wH4tSmDoZfWWdbLZMt9g14iq6ipkAGch0XOAEt.AH1NUOOKSMb2GQWmKWU._tjAuBiF53_vZl871obuZodbOIo.eqNCAGdl22pfgjdwtXvjzud8AWlAGfHNBONL5fV2wvYV6jRUCsH23YihAFVrtwNOiADqmD8R90yWsgShCYmpgGuW.JlEnHVYo4H5bqOwV3bPkFMIwtIB1DjkhfHm4LCMU9LUPMixJGWoqGoHYsuW0E5c6HMZxhOOFKJNOlDm6F0twXHC0xG5oKzVYMrbrRTP99kSmMy.WaTSLSMQpl0Fo6DGsJp3OwhqnTTRaabBOw6T2YrbtKf2shjJO2DnIDiBuPGx7yh0SstY468NE_9W1OpHPlMCC7Q4PoFJa_VrTe9HzBWw1aK1WFiNOzta9CWgtfVrm9ALmjKGo1EIRz61DLflOhKnEbr3kYB2i7u7KYEpjgxEgFTdwxpOgJkgsMIialAbMbpINT0E36pAecrOuZcZB4nw8IeT2ELusDRwlhxybitYWWGFSY15csVxI3.yMBzsPfMaIKkekUXxIa5ahe0CZGx2atxwuclPGrTn8IUKpdjOYw2qLkyy6XEcHZhqvS0gfSvwk10EF4Kvap2drEWbllQjrpgdJdmFWKWKfc600EZiGIZNOgVoKZa8gWewx_oTTJwsvOrby5NGu_74bpfiB87DtMJ8CXNONVtFWAB.19JFJ.3O.Zycyv6gmdAOQVzq8PeBAfcHzcgo.rs2sHIeqB8JSRjiIFqqWEAb02F028cDOqa0N1P5bJK4VFfYNbyVH8_4DOMlKxev.yErVhSNBB3xn2MZqrZO1b.WxZc7atr1v0X4s9ZEaFstHsxmBrkHEaR0sJQetttFP.SmoDDUL79KFfNL2INTghM31U7ACjghDe_MkjulPlpTVI.qZ.xPphIOKgi7zMed26DWJd0J0YGdl4A2UZ7zHt5q9tA.dntsd.qMZAzsWJZ9VGoE6kNB1Ewpy6iJFdw0lhWTMyV3IeT4vkFMkA2iRrPnjNd5wmy958Ik1ei2DDaW.pS4LhnCYX1IyBRqznJBpyLxYk1JIHsum5d02b9xb2XFHbLyU9IFo_R_Zax5qrNP7ak8wa9fADSmQysdxbSDBVjCtX5vBIKD6buuCPbg62OKvjpbU6gu8TP7wqHk0bJZdDb8XWsN884GEDDjmKMgdzzCi5QTAMOD9Po4rYlFmH22oHx6lC2Z9kpBqu_Mmqe.SuUyxmnSQmR32zAPGmapX2eR9FY7O7s044eG.rh8_T9Y1gz6tWunOJFZI2pGmuHrBRmU_NxOfK7.OKwyB6U4BUAnomprws.QHjLPCrnUrC7v3N4B16ISlpJcvvMmm3d4jYPBC8MPaQvPGdvP7j9.mBf6s91LRUtoNNME5zGKeDyWGx1BkLNq2.cFcnyivUnNUPXVJG7zeHkSMnJQHqSIkokAy4Pppy2rjK7wc_M332kXmfzJYtjUeH.fdy2OQ5qlqlytYme5S_f7dby6SkQrIc2QZq2eo5LtyAxwvISeUrflxz2WMOA2Zkwi1NsyRs5DgXIQ1s9KIqnN6ouKPEVmmPEEIMRG_pB5Fnhm9FfuEH1nh6IyKCF_kLh.mgtP1KLmmIyVM8M_WQoAbktb2mqGVyhwIMfoLjIlC4X3BfmRhG.zHGaHbkzyS8pMNT7JobE",mdrd: "syxMpG8SidDGtQ78UNyt.dksdgVH1NyBAnw0NFRBxmw-1739791562-1.2.1.1-AF3S0rcWS3h5vZDuZPYrHS_KXtLMf8U1Fhj6AoFc1vPXv95xbv3l8fWGFPHkt00VJPHm9CshzQVtOqclQct72Y1uvwA1m7jROo_D_P05hLmE6loXr4R48NDOA6N2l9_eBtk6RZMn6D7J3QueXIE696wjAn2RQwncnLLaYHiQH5kHBvYjXPLuFoWGJf.yPhV59jAFx8Ox_5KY3MAkJGZFeFyvzAle71BVdybIZ6nCOGW_ACw7gUy1Y7RocJFW2jqKrbgcInRYk8NXR4BjRUr6QqOylS1IeScbBUlyHpnoKXF7SHQ5.0IT49RRx_HCl_vKm.loKJ8E0qHQXsSD07_mjg8DzURxphkguUI2pif095ccCNerspsd6tKczq18hkAaOsAVibSJa75cNLSXIL1trpyLdoNiaCSSIAOoLR.8uzkBR0GxwZbwItT3pJ4kM0d.9rNUEC5vBfOunjqTZcrHye5V1KECUO0TsKHpXqLdcxbRssAOTsYRNEse8FZAE0XwCz80OL7C41xAKEuth6Vz60eIU_2_vXRCD_kl8RfkqowNRILhjYBvWVy34_9Hh7d.y7V5vjC2xFNUiHWoDYkCt23AKnQyJBu4oPhNWW_4FzFnoxELV24UvN4KdQYsCPEmogQU_1FH.fw9ZLFX9JI0TP.9kTNUl4uXD2XzXPcZ9DvYeEMMQSpKiMBnFFYA73JvKQE7w4orGIhZFt.8HDiNPFfUEnGSpJk1dMIpg1d2swANHZV1PxI25QFf498byPPG1l41nmZEqckrRPrfNT0MH2J8vOkwgPJKaVqIH34wPRe.I8RC.YnoL0Fg7bcFa1uIPvhLeH_hqnfw6Ik9iAvnvvhW37U3HPPSXfXMqKBaXDpGjhrMutChC8gfv_6iVIkN6mNCpKLqjpSw.ON8Ltrl0ygPplaI0fWejf1iuXEfd5f.9Ype6D5PizK_cOd3.A9NuRtolHixJrxGaRTmjdOdxSpsN5EW6pkPqfR3MQbp9c0lyBC3ltI4xti_pjpMtJtliqQKYlacslGDoWLEvavCsHthGDUmfaN33bRAlwUP4c6XKaui5WX9UyIipvwq0eUl23g5XezIF5VdSZ2tDs2hKb8YEmxc8bHDb_ak8muKB7KrDNbthqWK7mcVTRJoHct_N2ADcB1PxSMWnmWYKDHHFUzb2OkY8mi58IdBWYnnzAncahK8s10g3CeJZy9JxZvTarskUL2Hkvhz0oJY1prYlQvku9TMsivat8KMSCuIMGV2C2NYZ.woX0fYohw25aVWIHtw9m5vG1edWyWJfzLddejHdooI7q..AqFGsUO8WDiHKNIUsGWXSCY7ML0Bzh4WwytroE_vHu0avuSBLM7jQPf2iCPn2YwUzrJPLqTZTcGAFiaByepCXS6F_S3Nuitcas_uYHV1lLaLnthT04ZrKCT4j0nU6FJWDI8MCBpo_P0jxLZULCoEPh64E2_WSsyUo7h2L_CxopLAgZ6Lfi1jkxH_vRKtwhPO8IPG9sVlHGqZ3UYqjCddfcUp6ZjwHjA4U_HRgLkGGPaVWu31IOTTzagyXyuJsgDgehZNfWOmkagf1L456NxlRqeuMpmXAW7ENeCqZhOiNhmz_kkUnoipbYJRbxBoHXY3tTFet41wXjqcnZYhbmHcxXxGTQe1FHMHTMgi1ysMkLcKBFQ3zxHAufej7zuFei0xtyHt049esCQlauZ.Co6Y26_6IVRSVOXO0eFf46cmYXDIU1Q_kCwY.5zNyS1rnljU10oCVIY7Maept7_VJGFeR2fbhm4LOtmt7T0aT4qb5a8xSdgkeXvTmlQkkxNI87.SeLjS2blcLjZClxGTTFA1SgTYY4lTza_uXq7U6dIB8JfRT2MzZttUkvOWluAgVpu3aTDnmSBPo.iu2L8oDKeysHcRMfyVkGVSKaJ.Y0gAfzC93pea6QJ.0mclm_Txq5YieeNdoHSx4HBVN32kbzy_Dm5TZaBjTm0UnFvi0DB7NBsMf5N4aFWDqQ"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=91356b8f4aecf914';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, "\/search?q=P.K.&__cf_chl_rt_tk=YUNVgpC_Lb61CMMvq8FD3Gr_7b5_btOb0hsNyruzsDw-1739791562-1.0.1.1-GosTvseM1QfLInPRQpmh.9t5kQG.cGQ3Q4wHZ54hFuA" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>