GRE國內(nèi)題全部閱讀

GRE國內(nèi)題全部閱讀1990年04月SECTIONABecauseofitsaccuracyinoutliningtheEarth’ssubsurface,theseismic-reflectionmethodremainsthemostimportanttoolinthesearchforpetroleumreserves.Infieldpractice,asubsurfaceismappedbyarrangingaseriesofwave-trainsources,suchassmalldynamiteexplosions,inagridpattern.Aseachsourceisactivated,itgeneratesawavetrainthatmovesdownwardataspeeddetermineduniquelybytherock’selasticcharacteristics.Asrockinterfacesarecrossed,theelasticcharacteristicsencounteredgenerallychangeabruptly,whichcausespartoftheenergytobereflectedbacktothesurface,whereitisrecordedbyseismicinstruments.Theseismicrecordsmustbeprocessedtocorrectforpositionaldifferencesbetweenthesourceandthereceiver,forunrelatedwavetrains,andformultiplereflectionsfromtherockinterfaces.Thenthedataacquiredateachofthespecificsourcelocationsarecombinedtogenerateaphysicalprofileofthesubsurface,whichcaneventuallybeusedtoselecttargetsfordrilling.Modernarchaeologicalfindscanstillcontributemuchtothestudyofancientliterature.Forexample,fortyyearsagoasurveyoftheearlyGreekdramatistAeschylus’playswouldhavestartedwithTheSuppliantWomen.Manyfactorsinternaltotheplay,butperhapsmostespeciallytheprominenceofthechorus(whichinthisplayhasthemainrole,ledscholarstoconsideritoneofAeschylus’earlierworks.Theconsensuswasthatherewasadramatrulyreflectinganearlystageintheevolutionoftragedyoutofchorallyric.Theplaywasdatedasearlyasthe490’sB.C.,inanyevent,wellbeforeAeschylus’playThePersiansof472B.C.Then,in1952,afragmentofpapyrusfoundatOxyrhynchuswaspublishedstatingtheofficialcircumstancesandresultsofadramaticcontest.ThefragmentannouncedthatAeschyluswonfirstprizewithhisDanaidtetralogy,ofwhichTheSuppliantWomenistheopeningplay,anddefeatedSophoclesintheprocess.Sophoclesdidnotcompeteinanydramaticcontestbefore468B.C.,whenhewonhisfirstvictory.Hence,exceptbyspecialpleading(e.g.,thatthetetralogywascomposedearlyinAeschylus’careerbutnotproduceduntilthe460’sB.C.,theDanaidtetralogymustbeputafter468B.C.Inaddition,afewlettersinthefragmentsuggestthenameArchedemides,archonin463B.C.,thusperhapstyingtheplaystothatprecisedate,almostexactlyhalfwaybetweenAeschylus’SevenAgainstThebesof467B.C.andhisOresteia.Theimplicationofthepapyrusadministeredasevereshocktothevastmajorityofclassicalscholars,whohadconfidentlyassertedthatnotonlytheroleofthechorusbutalsolanguage,metrics,andcharacterizationallpointedtoanearlydate.ThediscoveryhasresultedinnolessthanatotalreevaluationofeverychronologicalcriterionthathasbeenappliedtoorderivedfromAeschylus’plays.Theactivityhasbeenbrisk,andanewcreedhasnowspread.TheprominenceofthechorusinTheSuppliantWomennowisseennotasasignofprimitivismbutasanalogoustothemassivechoralsongsoftheOresteia.Statisticshavebeenformulated,orreformulated,toshowthatstylisticallyTheSuppliantWomendoesactuallyoccupyapositionafterThePersiansandSevenAgainstThebes,whichnowbecomethe“primitive”plays,andbeforetheOresteia.Whilethenewdoctrineseemsalmostcertainlycorrect,theonepapyrusfragmentraisesthespecterthatanothermaybeunearthed,showing,forinstance,thatitwasaposthumousproductionoftheDanaidtetralogywhichbestedSophocles,andthrowingthedateoncemoreintoutterconfusion.Thisisunlikelytohappen,butitwarnsusthatperhapsthemostsalutaryfeatureofthepapyrusscrapisitsmessageoftheextremedifficultyofclassifyingandcategorizingrigidlythedevelopmentofacreativeartist.SECTIONBScholarsoftenfailtoseethatmusicplayedanimportantroleinthepreservationofAfricancultureintheUnitedStates.TheycorrectlynotethatslaverystrippedsomeculturalelementsfromBlackpeople—theirpoliticalandeconomicsystems—buttheyunderestimatethesignificanceofmusicinsustainingotherAfricanculturalvalues.Africanmusic,unlikethemusicofsomeothercultures,wasbasedonatotalvisionoflifeinwhichmusicwasnotanisolatedsocialdomain.InAfricanculturemusicwaspervasive,servingnotonlyreligion,butallphasesoflife,includingbirth,death,work,andplay.Themethodsthatacommunitydevisestoperpetuateitselfcomeintobeingtopreserveaspectsoftheculturallegacythatthatcommunityperceivesasessential.Music,likeartingeneral,wassoinextricablyapartofAfricanculturethatitbecameacrucialmeansofpreservingthecultureduringandafterthedislocationsofslavery.Traditionally,pollinationbywindhasbeenviewedasareproductiveprocessmarkedbyrandomeventsinwhichthevagariesofthewindarecompensatedforbythegenerationofvastquantitiesofpollen,sothattheultimateproductionofnewseedsisassuredattheexpenseofproducingmuchmorepollenthanisactuallyused.Becausethepotentialhazardspollengrainsaresubjecttoastheyaretransportedoverlongdistancesareenormous,wind-pollinatedplantshave,intheviewabove,compensatedfortheensuinglossofpollenthroughhappenstancebyvirtueofproducinganamountofpollenthatisonetothreeordersofmagnitudegreaterthantheamountproducedbyspeciespollinatedbyinsects.However,anumberoffeaturesthatarecharacteristicofwind-pollinatedplantsreducepollenwaste.Forexample,manywind-pollinatedspeciesfailtoreleasepollenwhenwindspeedsareloworwhenhumidconditionsprevail.Recentstudiessuggestanotherwayinwhichspeciescompensatefortheinefficiencyofwindpollination.Thesestudiessuggestthatspeciesfrequentlytakeadvantageofthephysicsofpollenmotionbygeneratingspecificaerodynamicenvironmentswithintheimmediatevicinityoftheirfemalereproductiveorgans.Itisthemorphologyoftheseorgansthatdictatesthepatternofairflowdisturbancesthroughwhichpollenmusttravel.Thespeedanddirectionoftheairflowdisturbancescancombinewiththephysicalpropertiesofaspecies’pollentoproduceaspecies-specificpatternofpollencollisiononthesurfacesoffemalereproductiveorgans.Providedthatthesesurfacesarestrategicallylocated,theconsequencesofthiscombinationcansignificantlyincreasethepollen-captureefficiencyofafemalereproductiveorgan.Acriticalquestionthatremainstobeanswerediswhetherthemorphologicalattributesofthefemalereproductiveorgansofwind-pollinatedspeciesareevolutionaryadaptationstowindpollinationoraremerelyfortuitous.Acompleteresolutionofthequestionisasyetimpossiblesinceadaptationmustbeevaluatedforeachspecieswithinitsownuniquefunctionalcontext.However,itmustbesaidthat,whileevidenceofsuchevolutionaryadaptationsdoesexistinsomespecies,onemustbecarefulaboutattributingmorphologytoadaptation.Forexample,thespiralarrangementofscale-bractcomplexesonovule-bearingpinecones,wherethefemalereproductiveorgansofconifersarelocated,isimportanttotheproductionofairflowpatternsthatspiraloverthecone’ssurfaces,therebypassingairbornepollenfromonescaletothenext.However,thesepatternscannotbeviewedasanadaptationtowindpollinationbecausethespiralarrangementoccursinanumberofnon-wind-pollinatedplantlineagesandisregardedasacharacteristicofvascularplants,ofwhichconifersareonlyonekind,asawhole.Therefore,thespiralarrangementisnotlikelytobetheresultofadirectadaptationtowindpollination.1990年10月SECTIONAIthasbeenknownformanydecadesthattheappearanceofsunspotsisroughlyperiodic,withanaveragecycleofelevenyears.Moreover,theincidenceofsolarflaresandthefluxofsolarcosmicrays,ultravioletradiation,andx-radiationallvarydirectlywiththesunspotcycle.Butaftermorethanacenturyofinvestigation,therelationoftheseandotherphenomena,knowncollectivelyasthesolar-activitycycle,toterrestrialweatherandclimateremainsunclear.Forexample,thesunspotcycleandthealliedmagnetic-polaritycyclehavebeenlinkedtoperiodicitiesdiscernedinrecordsofsuchvariablesasrainfall,temperature,andwinds.Invariably,however,therelationisweak,andcommonlyofdubiousstatisticalsignificance.Effectsofsolarvariabilityoverlongertermshavealsobeensought.TheabsenceofrecordedsunspotactivityinthenoteskeptbyEuropeanobserversinthelateseventeenthandearlyeighteenthcenturieshasledsomescholarstopostulateabriefcessationofsunspotactivityatthattime(aperiodcalledtheMaunderminimum.TheMaunderminimumhasbeenlinkedtoaspanofunusualcoldinEuropeextendingfromthesixteenthtotheearlynineteenthcenturies.TherealityoftheMaunderminimumhasyettobeestablished,however,especiallysincetherecordsthatChinesenaked-eyeobserversofsolaractivitymadeatthattimeappeartocontradictit.Scientistshavealsosoughtevidenceoflong-termsolarperiodicitiesbyexaminingindirectclimatologicaldata,suchasfossilrecordsofthethicknessofancienttreerings.Thesestudies,however,failedtolinkunequivocallyterrestrialclimateandthesolar-activitycycle,oreventoconfirmthecycle’spastexistence.Ifconsistentandreliablegeologicalorarchaeologicalevidencetracingthesolar-activitycycleinthedistantpastcouldbefound,itmightalsoresolveanimportantissueinsolarphysics:howtomodelsolaractivity.Currently,therearetwomodelsofsolaractivity.ThefirstsupposesthattheSun’sinternalmotions(causedbyrotationandconvectioninteractwithitslarge-scalemagneticfieldtoproduceadynamo,adeviceinwhichmechanicalenergyisconvertedintotheenergyofamagneticfield.Inshort,theSun’slarge-scalemagneticfieldistakentobeself-sustaining,sothatthesolar-activitycycleitdriveswouldbemaintainedwithlittleoverallchangeforperhapsbillionsofyears.ThealternativeexplanationsupposesthattheSun’slarge-scalemagneticfieldisaremnantofthefieldtheSunacquiredwhenitformed,andisnotsustainedagainstdecay.Inthismodel,thesolarmechanismdependentontheSun’smagneticfieldrunsdownmorequickly.Thus,thecharacteristicsofthesolar-activitycyclecouldbeexpectedtochangeoveralongperiodoftime.Modernsolarobservationsspantooshortatimetorevealwhetherpresentcyclicalsolaractivityisalong-livedfeatureoftheSun,ormerelyatransientphenomenon.ThecommonbeliefofsomelinguiststhateachlanguageisaperfectvehicleforthethoughtsofthenationspeakingitisinsomewaystheexactcounterpartoftheconvictionoftheManchesterschoolofeconomicsthatsupplyanddemandwillregulateeverythingforthebest.Justaseconomistswereblindtothenumerouscasesinwhichthelawofsupplyanddemandleftactualwantsunsatisfied,soalsomanylinguistsaredeaftothoseinstancesinwhichtheverynatureofalanguagecallsforthmisunderstandingsineverydayconversation,andinwhich,consequently,awordhastobemodifiedordefinedinordertopresenttheideaintendedbythespeaker:“Hetookhisstick—no,notJohn’s,buthisown.”Nolanguageisperfect,andifweadmitthistruth,wemustalsoadmitthatitisnotunreasonabletoinvestigatetherelativemeritsofdifferentlanguagesorofdifferentdetailsinlanguages.SECTIONBItisfrequentlyassumedthatthemechanizationofworkhasarevolutionaryeffectonthelivesofthepeoplewhooperatethenewmachinesandonthesocietyintowhichthemachineshavebeenintroduced.Forexample,ithasbeensuggestedthattheemploymentofwomeninindustrytookthemoutofthehousehold,theirtraditionalsphere,andfundamentallyalteredtheirpositioninsociety.Inthenineteenthcentury,whenwomenbegantoenterfactories,JulesSimon,aFrenchpolitician,warnedthatbydoingso,womenwouldgiveuptheirfemininity.FriedrichEngels,however,predictedthatwomenwouldbeliberatedfromthe“social,legal,andeconomicsubordination”ofthefamilybytechnologicaldevelopmentsthatmadepossibletherecruitmentof“thewholefemalesexintopublicindustry.”O(jiān)bserversthusdifferedconcerningthesocialdesirabilityofmechanization’seffects,buttheyagreedthatitwouldtransformwomen’slives.Historians,particularlythoseinvestigatingthehistoryofwomen,nowseriouslyquestionthisassumptionoftransformingpower.Theyconcludethatsuchdramatictechnologicalinnovationsasthespinningjenny,thesewingmachine,thetypewriter,andthevacuumcleanerhavenotresultedinequallydramaticsocialchangesinwomen’seconomicpositionorintheprevailingevaluationofwomen’swork.TheemploymentofyoungwomenintextilemillsduringtheIndustrialRevolutionwaslargelyanextensionofanolderpatternofemploymentofyoung,singlewomenasdomestics.Itwasnotthechangeinofficetechnology,butrathertheseparationofsecretarialwork,previouslyseenasanapprenticeshipforbeginningmanagers,fromadministrativeworkthatinthe1880’screatedanewclassof“dead-end”jobs,thenceforthconsidered“women’swork.”Theincreaseinthenumbersofmarriedwomenemployedoutsidethehomeinthetwentiethcenturyhadlesstodowiththemechanizationofhouseworkandanincreaseinleisuretimeforthesewomenthanitdidwiththeirowneconomicnecessityandwithhighmarriageratesthatshranktheavailablepoolofsinglewomenworkers,previously,inmanycases,theonlywomenemployerswouldhire.Women’sworkhaschangedconsiderablyinthepast200years,movingfromthehouseholdtotheofficeorthefactory,andlaterbecomingmostlywhite-collarinsteadofblue-collarwork.Fundamentally,however,theconditionsunderwhichwomenworkhavechangedlittlesincebeforetheIndustrialRevolution:thesegregationofoccupationsbygender,lowerpayforwomenasagroup,jobsthatrequirerelativelylowlevelsofskillandofferwomenlittleopportunityforadvancementallpersist,whilewomen’shouseholdlaborremainsdemanding.Recenthistoricalinvestigationhasledtoamajorrevisionofthenotionthattechnologyisalwaysinherentlyrevolutionaryinitseffectsonsociety.Mechanizationmayevenhaveslowedanychangeinthetraditionalpositionofwomenbothinthelabormarketandinthehome.(Thispassageisexcerptedfromanarticlethatwaspublishedin1982.Warm-bloodedanimalshaveelaboratephysiologicalcontrolstomaintainconstantbodytemperature(inhumans,37℃.Whythenduringsicknessshouldtemperaturerise,apparentlyincreasingstressontheinfectedorganism?Ithaslongbeenknownthatthelevelofserumironinanimalsfallsduringinfection.Garibaldifirstsuggestedarelationshipbetweenfeverandiron.Hefoundthatmicrobialsynthesisofsiderophores—substancesthatbindiron—inbacteriaofthegenusSalmonelladeclinedatenvironmentaltemperaturesabove37℃andstoppedat40.3℃.Thus,feverwouldmakeitmoredifficultforaninfectingbacteriumtoacquireironandthustomultiply.Cold-bloodedanimalswereusedtotestthishypothesisbecausetheirbodytemperaturecanbecontrolledinthelaboratory.KlugerreportedthatofiguanasinfectedwiththepotentiallylethalbacteriumA.hydrophilia,moresurvivedattemperaturesof42℃thanat37℃,eventhoughhealthyanimalspreferthelowertemperature.Whenanimalsat42℃wereinjectedwithanironsolution,however,mortalityratesincreasedsignificantly.Researchtodeterminewhethersimilarphenomenaoccurinwarm-bloodedanimalsissorelyneeded.1991年02月SECTIONAAsGilbertWhite,Darwin,andothersobservedlongago,allspeciesappeartohavetheinnatecapacitytoincreasetheirnumbersfromgenerationtogeneration.Thetaskforecologistsistountangletheenvironmentalandbiologicalfactorsthatholdthisintrinsiccapacityforpopulationgrowthincheckoverthelongrun.Thegreatvarietyofdynamicbehaviorsexhibitedbydifferentpopulationsmakesthistaskmoredifficult:somepopulationsremainroughlyconstantfromyeartoyear;othersexhibitregularcyclesofabundanceandscarcity;stillothersvarywildly,withoutbreaksandcrashesthatareinsomecasesplainlycorrelatedwiththeweather,andinothercasesnot.Toimposesomeorderonthiskaleidoscopeofpatterns,oneschoolofthoughtproposesdividingpopulationsintotwogroups.Theseecologistspositthattherelativelysteadypopulationshave“density-dependent”growthparameters;thatis,ratesofbirth,death,andmigrationwhichdependstronglyonpopulationdensity.Thehighlyvaryingpopulationshave“density-independent”growthparameters,withvitalratesbuffetedbyenvironmentalevents;theseratesfluctuateinawaythatiswhollyindependentofpopulationdensity.Thisdichotomyhasitsuses,butitcancauseproblemsiftakentooliterally.Foronething,nopopulationcanbedrivenentirelybydensity-independentfactorsallthetime.Nomatterhowseverelyorunpredictablybirth,deathandmigrationratesmaybefluctuatingaroundtheirlong-termaverages,iftherewerenodensity-dependenteffects,thepopulationwould,inthelongrun,eitherincreaseordecreasewithoutbound(barringamiraclebywhichgainsandlossescanceledexactly.Putanotherway,itmaybethatonaverage99percentofalldeathsinapopulationarisefromdensity-independentcauses,andonlyonepercentfromfactorsvaryingwithdensity.Thefactorsmakinguptheonepercentmayseemunimportant,andtheircausemaybecorrespondinglyhardtodetermine.Yet,whetherrecognizedornot,theywillusuallydeterminethelong-termaveragepopulationdensity.Inordertounderstandthenatureoftheecologist’sinvestigation,wemaythinkofthedensity-dependenteffectsongrowthparametersasthe“signal”ecologistsaretryingtoisolateandinterpret,onethattendstomakethepopulationincreasefromrelativelylowvaluesordecreasefromrelativelyhighones,whilethedensity-independenteffectsacttoproduce“noise”inthepopulationdynamics.Forpopulationsthatremainrelativelyconstant,orthatoscillatearoundrepeatedcycles,thesignalcanbefairlyeasilycharacterizedanditseffectsdescribed,eventhoughthecausativebiologicalmechanismmayremainunknown.Forirregularlyfluctuatingpopulations,wearelikelytohavetoofewobservationstohaveanyhopeofextractingthesignalfromtheoverwhelmingnoise.Butitnowseemsclearthatallpopulationsareregulatedbyamixtureofdensity-dependentanddensity-independenteffectsinvaryingproportions.InRaisinintheSun,LorraineHansberrydoesnotrejectintegrationortheeconomicandmoralpromiseoftheAmericandream;rather,sheremainsloyaltothisdreamwhilelooking,realistically,atitsincompleterealization.Oncewerecognizethisdualvision,wecanaccepttheplay’sironicnuancesasdeliberatesocialcommentariesbyHansberryratherthanasthe“unintentional”ironythatBigsbyattributestothework.IndeedacuriouslypersistentrefusaltocreditHansberrywithacapacityforintentionalironyhasledsomecriticstointerprettheplay’sthematicconflictsasmereconfusion,contradiction,oreclecticism.Isaacs,forexample,cannoteasilyreconcileHansberry’sintenseconcernforherracewithheridealofhumanreconciliation.Buttheplay’scomplexviewofBlackself-esteemandhumansolidarityascompatibleisnomore“contradictory”thanDuBois’famous,well-consideredidealofethnicself-awarenesscoexistingwithhumanunity,orFanon’semphasisonanidealinternationalismthatalsoaccommodatesnationalidentitiesandroles.SECTIONBSomerecenthistorianshavearguedthatlifeintheBritishcoloniesinAmericafromapproximately1763to1789wasmarkedbyinternalconflictsamongcolonists.Inheritorsofsomeoftheviewpointsofearlytwentieth-centuryProgressivehistorianssuchasBeardandBecker,theserecenthistorianshaveputforwardargumentsthatdeserveevaluation.Thekindofconflictmostemphasizedbythesehistoriansisclassconflict.YetwiththeRevolutionaryWardominatingtheseyears,howdoesonedistinguishclassconflictwithinthatlargerconflict?Certainlynotbythesideapersonsupported.AlthoughmanyofthesehistorianshaveacceptedtheearlierassumptionthatLoyalistsrepresentedanupperclass,newevidenceindicatesthatLoyalists,likerebels,weredrawnfromallsocioeconomicclasses.(Itisnonethelessprobablytruethatalargerpercentageofthewell-to-dojoinedtheLoyaliststhanjoinedtherebels.Lookingattherebelside,wefindlittleevidenceforthecontentionthatlower-classrebelswereinconflictwithupper-classrebels.Indeed,thewareffortagainstBritaintendedtosuppressclassconflicts.Whereitdidnot,thedisputingrebelsofoneoranotherclassusuallybecameLoyalists.Loyalismthusoperatedasasafetyvalvetoremovesocioeconomicdiscontentthatexistedamongtherebels.Disputesoccurred,ofcourse,amongthosewhoremainedontherebelside,buttheextraordinarysocialmobilityofeighteenth-centuryAmericansociety(withtheobviousexceptionofslavesusuallypreventedsuchdisputesfromhardeningalongclasslines.Socialstructurewasinfactsofluid—thoughrecentstatisticssuggestanarrowingofeconomicopportunityasthelatterhalfofthecenturyprogressed—thattotalkaboutsocialclassesatallrequirestheuseoflooseeconomiccategoriessuchasrich,poor,andmiddleclass,oreighteenth-centurydesignationslike“thebettersort.”Despitethesevaguecategories,oneshouldnotclaimunequivocallythathostilitybetweenrecognizableclassescannotbelegitimatelyobserved.OutsideofNewYork,however,therewereveryfewinstancesofopenlyexpressedclassantagonism.Havingsaidthis,however,onemustaddthatthereismuchevidencetosupportthefurtherclaimofrecenthistoriansthatsectionalconflictswerecommonbetween1763and1789.The“PaxtonBoys”incidentandtheRegulatormovementarerepresentativeexamplesofthewidespread,andjustified,discontentofwesternsettlersagainstcolonialorstategovernmentsdominatedbyeasterninterests.Althoughundertonesofclassconflictexistedbeneathsuchhostility,theoppositionwasprimarilygeographical.Sectionalconflict—whichalsoexistedbetweenNorthandSouth—deservesfurtherinvestigation.Insummary,historiansmustbecarefulaboutthekindofconflicttheyemphasizeineighteenth-centuryAmerica.Yetthosewhostresstheachievementofageneralconsensusamongthecolonistscannotfullyunderstandthatconsensuswithoutunderstandingtheconflictsthathadtobeovercomeorrepressedinordertoreachit.Since1953,manyexperimentalattemptstosynthesizethechemicalconstituentsoflifeunder“primitiveEarthconditions”havebeenperformed,butnoneoftheseexperimentshasproducedanythingapproachingthecomplexityofthesimplestorganism.Theyhavedemonstrated,however,thatavarietyofthecomplexmoleculescurrentlymakinguplivingorganismscouldhavebeenpresentintheearlyoceanandatmosphere,withonlyonelimitation:suchmoleculesaresynthesizedfarlessreadilywhenoxygen-containingcompoundsdominatetheatmosphere.ThereforesomescientistspostulatethattheEarth’searliestatmosphere,unlikethatoftoday,wasdominatedbyhydrogen,methane,andammonia.Fromthesestudies,scientistshaveconcludedthatthesurfaceoftheprimitiveEarthwascoveredwithoceanscontainingthemoleculesfundamentaltolife.Although,atpresent,scientistscannotexplainhowtheserelativelysmallmoleculescombinedtoproducelarger,morecomplexmolecules,somescientistshaveprecipitouslyventuredhypothesesthatattempttoexplainthedevelopment,fromlagermolecules,oftheearliestself-duplicatingorganisms.1991年04月SECTIONAIsadoraDuncan’smasterlywritingsonthedancerevealthedepthofherdeterminationtocreatealyricformoftheartwhichwasfreeofcharacterization,storytelling,andthetheatricalexhibitionofskills.Shewishedtodiscardthetraditionalmethodsandestablishedvocabulariesofsuchdanceformsasballetandtoexploretheinternalsourcesofhumanexpressiveness.Sheshunnedbodilyornamentationandstrovetouseonlythenaturalmovementsofherbody,undistortedbyacrobaticexaggerationandstimulatedonlybyinternalcompulsion.InherrecitalsDuncandancedtothemusicofBeethoven,Wagner,andGluck,amongothers,but,contrarytopopularbelief,shemadenoattempttovisualizeortointerpretthemusic;rather,shesimplyreliedonittoprovidetheinspirationforexpressinginnerfeelingsthroughmovement.Shedidnotregardthisuseofmusicasideal,however,believingthatshewouldsomedaydispensewithmusicentirely.Thatdaynevercame.Therecent,apparentlysuccessful,predictionbymathematicalmodelsofanappearanceofElNino—thewarmoceancurrentthatperiodicallydevelopsalongthePacificcoastofSouthAmerica—hasexcitedresearchers.JacobBjerknespointedoutover20yearsagohowwindsmightcreateeitherabnormallywarmorabnormallycoldwaterintheeasternequatorialPacific.Nonetheless,untilthedevelopmentofthemodelsnoonecouldexplainwhyconditionsshouldregularlyshiftfromonetotheother,ashappensintheperiodicoscillationsbetweenappearancesofthewarmElNinoandthecoldso-calledanti-ElNino.Theanswer,atleastifthecurrentmodelthatlinksthebehavioroftheoceantothatoftheatmosphereiscorrect,istobefoundintheocean.IthaslongbeenknownthatduringanElNino,twoconditionsexist:(1unusuallywarmwaterextendsalongtheeasternPacific,principallyalongthecoastsofEcuadorandPeru,and(2windsblowfromthewestintothewarmerairrisingoverthewarmwaterintheeast.Thesewindstendtocreateafeedbackmechanismbydrivingthewarmersurfacewaterintoa“pile”thatblocksthenormalupwellingofdeeper,coldwaterintheeastandfurtherwarmstheeasternwater,thusstrengtheningthewindstillmore.ThecontributionofthemodelistoshowthatthewindsofanElNino,whichraisesealevelintheeast,simultaneouslysendasignaltothewestloweringsealevel.Accordingtothemodel,thatsignalisgeneratedasanegativeRossbywave,awaveofdepressed,ornegative,sealevel,thatmoveswestwardparalleltotheequat