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: "languages.oup.com",cType: 'managed',cRay: '92dfc6787ab64d5d',cH: '4VGhYGpf2tU2.0gwk8o8C2W.zcvfyjhE3W6uX654p2M-1744262219-1.2.1.1-vtiorvQzgnCIOWku7FQu3GZI4Xks0alAUqrULfM_.gKXsEUwLtG1zEFOP8D6flP5',cUPMDTk: "\/research\/?__cf_chl_tk=JmifYHQclIrFL97A8oygt2IleBzkGbOk12jbBxEWLiQ-1744262219-1.0.1.1-y1bcmBg2q7Nrf0wmqlUbPsXRwG8WhhAFsCxjl2qC8i8",cFPWv: 'b',cITimeS: '1744262219',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/research\/?__cf_chl_f_tk=JmifYHQclIrFL97A8oygt2IleBzkGbOk12jbBxEWLiQ-1744262219-1.0.1.1-y1bcmBg2q7Nrf0wmqlUbPsXRwG8WhhAFsCxjl2qC8i8",md: "3Xffn8bvFxEq._ebrD9rcYU4rD.Y_A8lh5OfndwgNR4-1744262219-1.2.1.1-PJ1xJUKTquz64nmAK6sllF3rzOnLD1KN09vDHNr0vnIUJ6BUGHDLp3gZDX22HaCDh.m9HYyMuaKdb2P_UgAKmPLzeVKpWtylf.Mo7FdS1Hg.abkdCAcpl1B1RgIxaN5DB4wPMAMJBtBaUThYSW6xztKJuGgql9Jja.5Reh8zOVUxiyBA.cWIn9zS8lns9jA3FX5azA5TeEDboPvK6OD1kuqSLu.3thWxndtWRIlSN64qC.HheD_lRK_YUVHiaZn35zj3MCjR6lX1BdbbycgrO138oe9HOPGbUrsqMA8IxX2cEn3YEVkjDGIPrzVLnOp8j6ODpAQ3wOatWpwJQxSKx3tofyVrYjBnLjvlpLjf5tRzhn.Ui1AgUHl7Jw77cyFJnroMwTX16SSCc9Vj320VXWsZSPmfFgFbuXz9MwCuhW_077lnYQcXb3yzg5qsC6KStskYQ.FzUsBj3RIxojlmyCmJ3foHxQDnNdV0owZ3_FKMMhW.X6ThTXjRiQmVi1ZzYn1NrFd5ktNF2Ymf1EIEfnERsYG3CgPuV44yk4bZvJbPWuXYAEsclSPS8zCPQ9odG0cO9cVNQH23hdLpbCtoFCXGUg7..LwZ8IGTrmv0PX.gweXa1IRKmLDwT6er.xG7eIPqIwwTusm.ybLfLkr6XNoD0i3Fs1broZwL9ypyqepGyY4tRqCgrKubU6TermrREq7IWrrYcLT0.lAjWHaJJm7W.jQkVwXFMBWNH_j7um36bNmpAa_jQNu597FLuJCWUMGupyjpnYnEFAS8urmL0.J58seGbEZRtbTNhpbwe4V42hN5sAfvEw9YOl.fQClw7zmbBCo3jBBtbiw9jEdXfDipf5_kOggbCnWY0.oxU3ggXblVvhI7iXCBTotk12bnCjEgdSdQC5LVtCv5_tQ0ZBitkoBNCYBNHlt1G6MRHEjn2lrFJXXFGhB4Pp2onGiZ1qagb.BxJMGByUB1K0DJcIcGjj051Ifa3RjCru9wEnlBmpyF4xdLpPC5A.IrCTzaw6A9P9LXCSBPjK792z6YjUQHcZfUV2o.kG1LJmkEaDR5lv6TKKsy6BGiD6vt2mw1.87tfwNGdyCElHwCP4Nj8xrj6SBIRYMpiP439ikXy5dgYzndBH1e8ETfkMeaiRm63iri6caVce.Uk6OoLgDMB5yU_OwSCMt5Kz2FUIM_tb6ZOOHGhOE.FjwAtG60sN7Wy0_98I6qeUxliJ7H58aoEitkQvOzZoU_1uAZMybunjc",mdrd: "iNcVw1G09NoyoPa9FAhTFiWh_lhuF76f__3C15.TLuY-1744262219-1.2.1.1-a1cvPMLl1efBPiT6m9zbOWUMROBUoI7wZU6tUv4KtX2nIABrQh3jyCo5DSlioeX7vQLpfekunO1sUlO3mDH4TZLMMuIyIQ7UwKhdULiAi840cWUSDcLU.AeN.m.GSGcwVPyem7Qm7PHKT6swPdQO46.TpMh6yW5phDAfDDezh28rH62b5Pnjm.o5P14SadOZpBl2L2_f.VbB416h3yLU.YgAUltj.ovMPRaIru93fyG0upZDKdefvweLHku2LukNOM8whg2QWAPDa4_I85E8zcQl5RrdeZFvTFCc9Qvn5.lEqkwaLcrvBONMhvFnKKnpc4_FVLkiCofXbjM7idXYB.gTJG6ctja8pN.QE8dF5fnwZqhuRlv7FObYkpHLMAI4BpSAa4sHRZteQJ0OdE3OCrf5dR4Pd0PHqHcvXQkGU0BahWS2_.W.iIiuDEFcvuR0CRpSW968XWj3UjxWEz5ISJBORpFuiZqVXfP.r5.3NkilwX_XPdofRZk3z2c9nYCtQLzynzP9aiMCL_NxXQrQ8RP35zubbXIcQIAEvA5OizUgxHUykJJVWzORd.scjvHRHX_Drxxobjfl8WPA1dVsOjl.kY.enmDP.nri2ceSXKo3DoW1WDnv.ZeCZJXx.oAPemWsRe305c7qi9tz1tmGg1xG2C6DXEv5bofZ_fnTg5Q6yzVAUyKaiQPcSAgMcR1Mr9mr3kfi1dzdekJ78qifZyBzBHTnSz5SUx_Y5VZREozTS5FchvirpON2x9YqOUo5v6BHkpyo82wXbWlI1DHiGPioNCsjDzgoqX7XGsG178PhhmX2he5BQNwOgV_IY9nvVlxyf6rK54k7pC00TvAImV_7UOCqGVgqYUwYu0wcJSIx5IS.36bohBARYP.K4cm8tLaaeN_qS1sELa1PuzXviNUUXUd4C0gobvW5CevhUBii3XNCCBkjRa36PDhxxJSLnZETw5Nm19rcPuOa.DYXUOmpD3DAWjsmxDSbBi4P2Y5mni.EUr3KeAc0KlOO8oCowvmVcQt6AkZpDn4HgX99hXB1tQfr4uyDWT17CyoS9pNoZH_9Uaq1zMHoMhH4Zo3nV7uYRWDDziDOg9ncw.S5.FktrLPhxrAT3IYyiG9ffzbTKE2My6aUta_p7plKbSGbaki9B3cCu2sFKLbhCWzTCU8rLZ0vQfqICZvh4U75ME1U5wB5D27drLB_3yacNKj_EvKpHSKRXQOpU5eI0C3q.UqAV9ZzZ6D9EUDYocQrlmtQbUVoXIxTypaU9JXK9n0GnpkBVRbDQ9NKE13RaeswT.RwQn2H_yav8Z0g6f2fULCRidjo.sADqQenBbGcxBwB8MD0vlv_jnoNPFTcLRxSqPa4.pZnxjVGV9UNFrQaCRSrxsGWhxKKDzQfJHhcnwtKeWQPPHypCVLjTncnzK7qiD_ZhPeSnzqxqdB6QgBXGDZQha19Aae8EBc9nrLBdzMU7A8cRDXt6mS6NYohmmegsAL8byh5i42Taq6xXLHUgACFKDS30Rh_.el_bLm3hXMDbmOG7uL23GR8Rgj2IvFYQ.ufFkRwjQb1As2LtEKfZATfoAWStsvfXoXArXpN4s9ddp4V5cX0tcztLCevd6YW3VO4zJQmC4YBTsxqpx3kBgX48tE1J6xnk1O6ucIw7A3kmjmGOa3lQQISoR4xnmTT_gtqnPZFqTDEYKmRghLyAgWLwaTvRhC.GfCSwFFmIBDlyeZRCri..mlIApOvOn5cHUp2DgtoS2tyn4Vd4YIL_4XUaIaNhbJAh4vEFl1F.XXfTMTbQNJwF9GjBhg2WUdDCxENK6h_xO0OCho5e9hktpRS7VM.14AipRCOf936Rwq44XHgU3WVDGyOY2LnU5.UjozTdLxBEaZjOcZ2M6dqPjLNlYCUuYdJYqISQ8.39tSFozHP_6rCdavTmnQHFdOy0mQO4Uo6cd1_zAXqH9s2baFTFGt0smcK3qu80LxvuRU8vG5gMSqv93wmbhCi5KKrduzQT7nKIxxYtCsqDbMha2KYJfB0wSBRzRop05octRhW"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92dfc6787ab64d5d';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, "\/research\/?__cf_chl_rt_tk=JmifYHQclIrFL97A8oygt2IleBzkGbOk12jbBxEWLiQ-1744262219-1.0.1.1-y1bcmBg2q7Nrf0wmqlUbPsXRwG8WhhAFsCxjl2qC8i8" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>