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="390"></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: 'managed',cRay: '9198db1a4e09fde8',cH: 'NhTIvbkrlv8Q4LZBGPUINR3WQzA_Fa4G0p5UbTbNZzs-1740834221-1.2.1.1-aN4s1LIG053gnJORWJ.k0vobyW3D9yqnn9avMR64Ea_m8M1KMmDZfXGgIX7tJTVK',cUPMDTk: "\/search?q=positive%20emotions.&__cf_chl_tk=GD0xUDrlf4Dp_tMAHM7hAJQsN7vRXby3052LP5vMCUM-1740834221-1.0.1.1-HEu80cAapjUTL37It8KJD.JMaPf_fudOx.X5DeU_qUc",cFPWv: 'b',cITimeS: '1740834221',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "",fa: "\/search?q=positive%20emotions.&__cf_chl_f_tk=GD0xUDrlf4Dp_tMAHM7hAJQsN7vRXby3052LP5vMCUM-1740834221-1.0.1.1-HEu80cAapjUTL37It8KJD.JMaPf_fudOx.X5DeU_qUc",md: "RjVL2dS2rKlz0mAhmNnEsU7eZHkKNJyMgYKe4AF5fgQ-1740834221-1.2.1.1-5Zg8LR6gTSxE2KPxODNwFeHHLPQ.kx7B8tnYhoDN7B724XDnqZT7C8ETMOkpkfGLn.45DNCdLSkz6i0V6NP5jc11k7pIOu5Kc3mr1PhEtwcBBDoPHATUgbpWjN2A7JGZ6LjBB5.Ob3zYULIxMTdnV3adRuT72h2gmTuxUIuMqxN17VOi69HO3PW86IG1emNg1E01i4twl0bJJV6tz_D4jkEEQrcGjpfPGv3q8O481RQS.t9_MkBVJHoo9b3NqpRehHUGBsiAcccT.K3s8h_l7eb5tnHMsA_9Y2ZLzrMIz24D1QSAhJaPibi966XhWqsECPSlqcKlZCOFkbCrRgWO1vFoDKNg8M.9wPQ_b39_wzqU.iqvq2vMmAziHToZJBUDhqfrDchp9tXoYkCRVJnsaQ.FLHsimD_sKNNe5JV4KTAFnNscJ9ErIMSSy8rybI.62R7vDr6nHuU8vFA7STtqDavDAeXsB1cKQp1Uf1NuqII2cJOfa.LtFQRDg0fddxoN1Q4w1UBlYVBFCncYsPw3dvt7grMYqZaRM2pwTqITyRfKKJGvNt_.uCeCJ4DXOxn8z3fjyfI.ad2sDkA7lnZJw8lLubBS7xjvjjsxM4wsh9ri91fkXvBeLM31HFKcukJUV0LDuNP.uGL0WbtQUnbQ_ZFXwQlbLvDI_l7fbO9L.7ukI3.N3rCr_pdX48Xv6sqekVGNIKswtAyqSqrLWok3pga4UQbtiLTIg9WM_aNms6ijP4Lfkl2rJm59sN8YCWyOGZ6UtXpyHAR.YnDl.Xcp8drh.nJ3Up9xbpSswNy4vt.QRf4nD3.sYlfQN2Rav9mrPIit7c_0wJ0ki4sNHvTQb9mZ4ecAUDaKfpzbnklHauIODw8oF35HUzk__mpqM3uJP.blzVUMTkODjMoleRR_Y2iXe07URYmcmVhIskZTVu8sH8LE4ZtYH9VqUCxPCcsgNz9OdTlXxZtYtZIlbC5TaQBLKYFfq89JAXgWH2qFmUXusm4s06jUsfNXwAdLhGftEG6x58eP1P_.I1LZaSHFoQLV4GS9rQ_Yw6VBlVy1mWqtnKnh5bA85JLeyr9hssFsNTFuB_D3fKDPrjJT7YCQDqPW77iefbZEGG98Yj.cYsxeC5Oqap_nRuplqKmO0WCf0UlAR487VPRskAzTzyaGRiMK75bA1txg.zkVfu0nTYeikSGjAcLriMFM4lJ9yKDcVksEE2b9T1GPD63EtsxHKJyT2W8xwQzUJ_L1d4N0WXeUhCu10wsK7hXaRNeV3Jn6",mdrd: "fI.IsuFLK9JNofHjm6UcQXJvSAQQoa_kdGkmRw36TVI-1740834221-1.2.1.1-axAnz0l6ve8uMVhT6AErNnzVAIWcyDzecXHKrXYCqaNaSLtdQKVztomC7OioDfPIW1Hx0hVFB6mP8UIJx5V52B9dLEB2GlUepvYK8GO2ZGxW5Eim65BSxHi8Jw1aVOhlxli3Qe1zflk7j4rpjLYHbzsdRY595tC.EksG_KUs0FnkVj4.vtJjIkBm8vegNYLgKDidppI3jTNbdYRO9V5p_WHov2W8r52UAl1Yq.8eJZocJZm8zAUV8Dhv3JHvMlqXBsytl.enHgqqCxMdk5T6Jzm3is34MBxe5yAeoyXxVpIBUHAdXiS993STVN36hRQlaR4Nzopm3qMoG3Ji5iBLWFYfx3DLthtRvNFDiEFpbayOC4CaLaFu6jW82z88C8MZ300sUxCLv45kXybTE.vNltJVUiJL9H6GgiHsI664weDGz6nba9OAnrDy2chWTHRSodDd67v0tuxFFZXCm6eojj1KJM2vQ1kKT3ke0XTTypW8KC_hVc9h5TUTexK5OlDGHJh3AbLswoZrQX6n5Psu2wqkqqVHt932IMTMR3ro2cJn3ZGQ_HLTXGLWw5dh.tfRX4MWjrGt8R4PHLNwKf08CZ5AIZNusxc8fjhvsraiK2vqVXnQeIdy3o280CIBScNADob43CneNMlS38sj0Pg4qjxAUzlz3AHEGKp6nRBGrIPwM4mKq5XL9NXTeZ3MA0H6HE6Rk9VcgfjErHUSJjNYOMMqZBMgTNJ9D6heX5DFUumBOfC_P6SMK6LC1T6K2GHoqqz3lg.xVXgrCwxAnU.MK3RNEDygVAKrcu7EftD6tLGtwIJmWRf7PQGXUbDgyHAV9ITv6UZlmnMDOO.UpXehtA0X0VazqinSjvWQypO3sOGT.5Bb_nR0AwsoVyE2ne0nxTfSv34Yl2FhSnww0rBVv3QdNh2HuvlC_WWNykEZzg9DTGe.dMzjxvN4huK5AiHf8_iSml114tpKw.aCoBrt1yuJrHC9hpMuRWFxePaW.2uciJaZsbgqjhBeLu6BXuCTUXSky1wZHvU0h7pkTbJtPthgQlPkike_3h9pRHjwL.h.JTbbEyNztgXnc9xnaYQOBT1Ypk1ROXuZd8_CD6tmhvjaQQd5FVOcDH3geSyirjipWIFK.au75LqN5e310KPQ7Jlkyo5eSG7CzS1GLtb8Un8DJdMo.eBO5HpmGDS19k..s5o2cX1s3H7uPkUQXBz3UWYUyYhNnPQ3lMI1kTQzAKCVJXeF4vwSjnBi7vNVSkud77B0p0tno0mQen7j44GZU4Q95mxR76LmyMmBoPw5Pp2A2A4Dth6_qYNfFKhl3puyaXuMtPJCw7kxKdjz55XPy1tDseXe6pcIE7TZ_MOh.tB2iqqfixvzNYZgh1UepA02bKFEffjEH4b6WJA5cCdx1LmzDydBXDLnaRhXsIosIZ2BsvVJLt16_ujcuKg4T4xMYnVESpeT2Q23sUJ_R21i4MW90ZerUwHH_11c9oD7eEkNVKI6o4_ude.ugjC7ePNVpGpocuiMYKcamqkM4f.7lGvE8gOqM3bRwpxY3hKMSohyI5viaMOle_w4I4TtflTbxonU0pX8pz.AJtjzziJ02HMfM4zBFQ5Fop7uQb3mP6zZpGn7xj25pddex.R8l4x2dxjSXTYRCBnjJNmCjYnA5Wqr.LlDo.TaFv8.XNVABIf1jU95Q8WnuPZfS.X.o2cLBPJ2uCg.mnytmQ9siU1Lg5ukDgouUPtiHW7vcHRM3I2FY0fdXo6BtgSEmE6FtS1Es5vncl1dWlJvyN6d1_wDYVT_j6YNYPbwPgxVzEcxY7GOZAMXhs83HYR3rprkKrMLtLZFxliJ8I5S3Z983KX9QcSoVrqKAfpIEp3Wt.fc1uRyYJ6DqGRATHDHwTMWsAi6sqtAYXgxk5OaeB63ShQwYDgubByXomAURApJzF9uouzGRwqyOYzxPEQMMukvJBhsbYXI2Vg6FnY3iq2py17r"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=9198db1a4e09fde8';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=positive%20emotions.&__cf_chl_rt_tk=GD0xUDrlf4Dp_tMAHM7hAJQsN7vRXby3052LP5vMCUM-1740834221-1.0.1.1-HEu80cAapjUTL37It8KJD.JMaPf_fudOx.X5DeU_qUc" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>