雅思阅读：高频文章（11-20）汇编

WhatDoestheConsumerMARKETINGpeoplearenolongerpreparedtotakeyourwordforitthatyoufavouroneproductoveranother.Theywanttoscanyourbraintoseewhichoneyoureallyprefer.Usingthetoolsofneuroscientists,WhatDoestheConsumerMARKETINGpeoplearenolongerpreparedtotakeyourwordforitthatyoufavouroneproductoveranother.Theywanttoscanyourbraintoseewhichoneyoureallyprefer.Usingthetoolsofneuroscientists,suchaselectroencephalogram(EEG)mappingandfunctionalmagnetic-resonanceimaging(fMRI),theyaretryingtolearnmoreaboutthemental,processesbehindpurchasingdecisions.Theresultingfusionofneuroscienceandmarketingisinevitably,beingcalledThefirstpersontoapplybrain-imagingtechnologyinthiswaywasGerryZaltmanofHarvardUniversity,inthelate1990s.Theidearemainedinobscurityuntil2001,whenBrightHouse,amarketingconsultancybasedinAtlanta,Georgia,setupadedicatedneuromarketingarm,BrightHouseNeurostrategiesGroup.(BrightHouselistsCoca-Cola,DeltaAirlinesandHomeDepotamongitsclients.)Butthecompany'snamemayitselfsimplybeanexampleofclevermarketing.BrightHousedoesnotscanpeoplewhileshowingthemspecificproductsorcampaignideas,butbasesitsworkontheresultsofmoregeneralfMRI-basedresearchintoconsumerpreferencesanddecision-makingcarriedoutatEmoryUniversityinAtlanta.Canbrainscanningreallybeappliedtomarketing?Thebasicprincipleisnotthatdifferentfromfocusgroupsandothertraditionalformsofmarketresearch.AvolunteerliesinanfMRImachineandisshownimagesorvideoclips.Inplaceofanintervieworquestionnaire,thesubject'sresponseisevaluatedbymonitoringbrainactivity.fMRIprovidesreal-timeimagesofbrainactivity,inwhichdifferentareas'lightup'dependingonthelevelofbloodflow.Thisprovidescluestothesubject'ssubconsciousthoughtpatterns.Neuroscientistsknow,forexample,thatthesenseofselfisassociatedwithanareaofthebrainknownasthemedialprefrontalcortex.AflowofbloodtothatareawhilethesubjectislookingataparticularlogosuggeststhatheorsheidentifieswiththatAtfirst,itseemedthatonlycompaniesinEuropewerepreparedtoadmitthattheyusedneuromarketing.Twocarmakers,DaimlerChryslerinGermanyandFord'sEuropeanarm,ranpilotstudiesin2003.Butmorerecently,Americancompanieshavebecomemoreopenabouttheiruseofneuromarketing.LiebermanResearchWorldwide,amarketingfirmbasedinLosAngeles,iscollaboratingwiththeCaliforniaInstituteofTechnology(Caltech)toenablemoviestudiostoconsultancy,FKFResearch,hasbeenstudyingtheeffectivenessofcampaigncommercialsusingneuromarketingtechniques.Whetherallthisisanymorethanamodem-dayversionofphrenology,theVictorianobsessionwithlinkinglumpsandbumpsintheskulltopersonalitytraits,isunclear.Therehavebeennolarge-scalestudies,soscansofahandfulofsubjectsmaynotbeareliableguidetoconsumerbehaviouringeneral.Ofcourse,focusgroupsandsurveysareflawedtoo:strongpersonalitiescansteertheoutcomesoffocusgroups,andsomepeoplemaybeuntruthfulintheirresponsestoopinionpollsters.Andevenhonestpeoplecannotalwaysexplaintheirpreferences.Thatisperhapswhereneuromarketinghasthemostpotential.Whenaskedaboutcoladrinks,mostpeopleclaimtohaveafavouritebrand,butcannotsaywhytheypreferthatbrand'staste.unpublishedstudyofattitudestowardstwowell-knowncoladrinks,BrandAandBrandB,ABCDEFtesting—fMRIscanningshowedthatdrinkingBrandBlituparegioncalledtheventralputamen,whichisoneofthebrain'srewardcentres,farmorebrightlythanBrandA.Butwhentoldwhichdrinkwaswhich,mostsubjectssaidtheypreferredBrandA,whichsuggeststhatitsstrongerbrandoutweighsthemorepleasanttasteoftheotherdrink.Peopleformmanyunconsciousattitudesthatareobviouslybeyondtraditionalmethodsthatutiliseintrospection,saysStevenQuartz,aneuroscientistatCaltechwhoiscollaboratingwithLiebermanResearch.Withover100billiondollarsspenteachyearonmarketinginAmericaalone,anyfirmthatcanmoreaccuratelyanalysehowcustomersrespondtobrandscouldmakeafortune.Consumeradvocatesarewary.GaryRuskinofCommercialAlert,alobbygroup,thinksexistingmarketingtechniquesarepowerfulenough."Already,marketingisdeeplyimplicatedinmanyseriouspathologies",hesays.'Thatisespeciallytrueofchildren,whoaresufferingfromanepidemicofmarketing-relateddiseases,includingobesityandtype-2diabetes.Neuromarketingisatooltoamplifythesetrends.'Dr.Quartzcountersthatneuromarketingtechniquescouldequallybeusedforbenignpurposes.'Therearewaystoutilisethesetechnologiestocreatemoreresponsibleadvertising,hesays.Brain-scanningcould,forexample,beusedtodeterminewhenpeoplearecapableofmakingfreechoices,toensurethatadvertisingfallswithinthosebounds.Anotherworryisthatbrain-scanningisaninvasionofprivacyandthatinformationonthepreferencesofspecificindividualswillbemisused.Butneuromarketingstudiesrelyonsmallnumbersofvolunteersubjects,sothatseemsimplausible.Criticsalsoobjecttotheuseofmedicalequipmentforfrivolousratherthanmedicalpurposes.ButasTimAmbler,aneuromarketingresearcherattheLondonBusinessSchool,says,'Atoolisatool,andiftheownerofthetoolgetsdecentrentforhiringitout,thenthatsubsidisesthecostoftheequipment,andeverybodyGHIPerhapsmorebrain-scanningwillsomedayexplainwhysomeneuromarketing,butothersdoReadingPassage2hastenparagraphsA-ChoosethecorrectheadingforParagraphsB-Gfromthelistofheadingsbelow.Writethecorrectnumber(i-x)inboxes14-19onyouranswersheetListofHeadingAdescriptionoftheprocedureandAninternationalresearchAnexperimenttoinvestigateconsumerMarketingwithanalternativeAmisleadingnameforApotentiallyprofitablelineofMedicaldangersoftheInternaldrawbackstomarketingBroadeningWhatisneuromarketing?ExampleParagraphA14Paragraphwiththeopinioncreditedtohim.WritethecorrectletterA-Finboxes20-22onyouranswersheet.20StevenQuartzGaryTimListofANeuromarketingcouldbeusedtocontributetowardsthecostofmedicaltechnologyBNeuromarketingcoulduseintrospectionasatoolinmarketingresearch.CNeuromarketingcouldbeameansoftreatingmedicalproblems.DNeuromarketingcouldmakeanexistingproblemworse.ENeuromarketingcouldleadtothemisuseofmedicalFNeuromarketingcouldbeusedtopreventtheexploitationofCompletethesummarybelowusingwordsfromthepassage.ChooseONEWORDONLYfromthepassageforeachanswer.Writeyouranswersinboxes23-26onyouranswersheet.Neuromarketingcanprovidevaluableinformationonattitudestoparticular23 Itmaybemorereliablethansurveys,wherepeoplecanbe24 ,orfocusgroups,wheretheymaybeinfluencedbyothers.Italsoallowsresearcherstoidentifythesubject's25 However,somepeopleareconcernedthatitcouldleadtoproblemssuchasanincreaseindiseaseamong viFDAviFDADetectionofameteoriteAsthesunroseoverpicturesqueLakeBosumtwi,ateamofSyracuseUniversitypreparedforanotherDetectionofameteoriteAsthesunroseoverpicturesqueLakeBosumtwi,ateamofSyracuseUniversitypreparedforanotherdayofusingstate-of-the-artequipmenttohelpunlockthemysterieshiddenbelowthelakebottom.NestledintheheartofGhana,thelakeholdsanuntappedreservoirofinformationthatcouldhelpscientistspredictfutureclimatechangesbylookingatevidencefromthepast.Thisinformationwillalsoimprovethescientist’sunderstandingofthechangesthatoccurinaregionstuckbyamassivemeteorite.Theproject,ledbyearthsciencesprofessorChristopherScholzoftheCollegeofArtsandSciencesandfundedbytheNationalScienceFoundation(NSF),isthefirstlarge-scaleefforttostudyLakeBosumtwi,Earth’ssurface.Theresultingcraterisoneofthelargestandmostwell-preservedgeologicallyyoungcratersintheworld,saysScholz,whoiscollaboratingontheprojectwithresearchersfromtheUniversityofSouthCarolina,theUniversityofRhodeIsland,andseveralGhanaianinstitutions.“Ourdatashouldprovideinformationaboutwhathappenswhenanimpacthitshard,pre-Cambrian,crystallinerocksthatareabillionyearsold”,hesays.Equallyimportantisthefactthatthelake,whichisabout8kilometersindiameter,hasnonaturaloutlet.Therimofthecraterrisesabout240metersabovethewater’ssurface.Streamsflowintothelake,Scholzsays,butthewaterleavesonlybyevaporation,orbyseepingthroughthelakesediments.Forthepastmillionyears,thelakehasactedasatropicalraingauge,fillinganddryingwithchangesinprecipitationandthetropicalclimate.Therecordofthosechangesishiddeninsedimentbelowthelakebottom.“Thelakeisoneofthebestsitesintheworldforthestudyoftropicalclimatechange,”Scholzsays.“ThetropicsaretheheartenginefortheEarth’sclimate.Tounderstandglobalclimate,weneedtohaverecordsofclimatechangesfrommanysitesaroundtheworld,includingthetropics.”Beforetheresearcherscouldexplorethelake’ssurface,theyneedaboatwithalarge,workingdeckareathatcouldcarryeighttonsofscientificequipment.Theboat-dubbedR/VKilindi-wasbuiltinFloridalastyear.Itwasconstructedinmodulesthatweredismantled,packedinsideashippingcontainer,andreassembledovera10-dayperiodinlateNovemberandearlyDecember1999intheruralvillageofAbono,Ghana.TheresearchteamthenspentthenexttwoweekstestingtheboatandequipmentbeforereturningtotheUnitedStatesfortheholidays.Inmid-January,fivemembersoftheteam-KeelyBrooks,anearthsciencesgraduatestudent;PeterCattaneo,aresearchanalyst;andKiramLezzar,apostdoctoralscholar,allfromSU;JamesMcGill,ageophysicalfiledengineer;andNickPeters,aPh.D.StudentingeophysicsfromtheUniversityofMiami-returnedtoAbonotobegincollectingdataaboutthelake’ssubsurfaceusingatechniquecalledseismicreflectionprofiling.Inthisprocess,ahigh-pressureairgunisusedtocreatesmall,pneumaticexplosionsinthewater.Thesoundenergypenetratesabout1,000to2,000metersintothelake’ssubsurfacebeforebouncingbacktothesurfaceofthewater.Thereflectedsoundenergyisdetectedbyunderwatermicrophones-calledhydrophones-embeddedina50-meterlongcablethatistowedbehindtheboatasitcrossesthelakeinacarefullydesignedgridpattern.On-boardcomputersrecordthesignals,andtheresultingdataarethenprocessedandanalyzedinthelaboratory.“Theresultswillgiveusagoodideaoftheshapeofbasin,howthickthelayerofsedimentare,andwhenandwherethereweremajorchangesABCDEFlake’ssubsurfaceandthelayersofsedimentthathavebeenlaidTeammembersspentaboutfourweeksinGhanacollectingthedata.Theyworkedsevendaysaweek,arrivingatthelakejustaftersunrise.Onagoodday,wheneverythingwentasplanned,theteamcouldcollectdataandbebackatthedockbyearlyafternoon.Exceptforanewrelativelyminoradjustments,theequipmentandtheboatworkedwell.Problemsthatarosewereprimarilynon-scientific-treestumps,fishingnets,culturalbarriers,andoccasionalmisunderstandingswithlocalvillagers.LakeBosumtwi,thelargestnaturalfreshwaterlakeinthecountry,isscaredtotheAshantipeople,whobelievetheirsoulscometothelaketobidfarewelltotheirgod.Thelakeisalsotheprimarysourceoffishforthe26surroundingvillages.Conventionalcanoesandboatsareforbidden.Fishermentravelonthelakebyfloatingontraditionalplankstheypropelwithsmallpaddles.Beforetheresearchprojectcouldbegin,ScholzandhisGhanaiancounterpartshadtosecurespecialpermissionformtribalchiefstoputtheR/VKilindionthelake.Whentheteambegangatheringdata,rumorsflewaroundthelakeastowhytheresearcherswerethere.“Somethoughtweweredredgingthelakeforgold,othersthoughtweweregoingtodrainlakeorthatwehadboughtthelake,”Cattaneosays,“Butoncethelocalpeopleunderstoodwhywewerethere,theywereveryhelpful.”DothefollowingstatementsagreewiththeinformationgiveninReadingPassage1?Inboxes14-18onyouranswersheet,writeTRUEifthestatementistrueFALSEifthestatementisfalseNOTGIVENiftheinformationisnotgivenintheWiththeinvestigationofthelake,scientistmaypredicttheclimatechangesintheThewaterstoredinLakeBosumtwiwasgoneonlybyseepingthroughthelakeHistoricalclimatechangescanbedetectedbytheanalysisofthesedimentintheThegreatestobstacletoresearchofscientistshadbeentheinterferencebythelocalsduetotheirindigenousbelieves.GHITherearethreestepsofcollectingdatafromthelakeasfollowings,pleasefillingintheblanksintheFlowChartbelow:CompletethefollowingsummaryoftheparagraphsofReadingPassage,usingnomorethanthreewordsfromtheReadingPassageforeachanswer.Writeyouranswersinboxes23-27onyouranswersheet.Theboat-doubleCompletethefollowingsummaryoftheparagraphsofReadingPassage,usingnomorethanthreewordsfromtheReadingPassageforeachanswer.Writeyouranswersinboxes23-27onyouranswersheet.Theboat-doubleR/VKilindicrossedthelakewasdismantledandstoredina23.technologytheyusedcalled24;theycreatedsoundenergyinto1000-2000metresintothebottomofthelake,andseparatedequipmenttocollectthereturnedwaves.Thenthedatahadbeenanalyzedandprocessedinthe25.Scholzalsoaddedthattheywerenow26viewofthesedimentorsub-imageinthebottomofthelake.Wholesetofequipmentworkswellyettheshipshouldavoidphysicalbarrierincludingtreestumpsor27floatingonthesurfaceontheNOT(high-pressure)energy/soundwaveshipNOT(high-pressure)energy/soundwaveshipSeismicfishingLifecode:ALifecode:AOnanairportshuttlebustotheKavliInstituteforTheoreticalPhysicsinSantaBarbara,Calif,ChrisWigginstookacolleague'sadviceandopenedaMicrosoftExcelspreadsheet.Ithadnothingtodowiththetalkonbiopolymerphysicshewasinvitedtogive.Ratherthecolumnsandrowsofnumbersthatstaredbackathimreferredtothegeneticactivityofbuddingyeast.Specifically,thenumbersrepresentedtheamountofmessengerRNA(mRNA)expressedbyall6,200genesoftheyeastoverthecourseofitsreproductivecycle.“ItwasthefirsttimeIeversawanythinglikethis,"Wigginsrecallsofthatspringdayin2002."Howtomakesenseofallthesedata?"BInsteadofshirkingfromthisquestion,the36-year-oldappliedmathematicianandphysicistatColumbiaUniversityembracedit-andnowsixyearslaterhethinkshehasananswer.Byforayingintofieldsoutsidehisown,Wigginshasdrudgeduptoolsfromabranchofartificialintelligencecalledmachinelearningtomodelthecollectiveprotein-makingactivityofgenesfromreal-worldbiologicaldata.Engineersoriginallydesignedthesetoolsinthelate1950stopredictoutputfrominput.Wigginsandhiscolleagueshavenowbroughtmachinelearningtothenaturalsciencesandtweakeditsothatitcanalsotellastory—onenotonlyaboutinputandoutputbutalsoaboutwhathappensinsideamodelofgeneregulation,theblackboxinbetween.CTheimpetusforthisworkbeganinthelate1990s,whenhigh-throughputtechniquesgeneratedmoremRNAexpressionprofilesandDNAsequencesthaneverbefore,"openingupacompletelydifferentwayofthinkingaboutbiologicalphenomena,"Wigginssays.KeyamongthesetechniqueswereDNAmicroarrays,chipsthatprovideapanoramicviewoftheactivityofgenesandtheirexpressionlevelsinanycelltype,simultaneouslyandundermyriadconditions.Asnoisyandincompleteasthedatawere,biologistscouldnowquerywhichgenesturnonoroffindifferentcellsanddeterminethecollectionofproteinsthatgiverisetoacell'scharacteristicfeatures-healthyordiseased.DYetpredictingsuchgeneactivityrequiresuncoveringthefundamentalrulesthatgovernit.“Overtime,theseruleshavebeenlockedinbycells,”saystheoreticalphysicistHarmenBussemaker,nowanassociateprofessorofbiologyatColumbia."Evolutionhaskeptthegoodstuff."Tofindtheserules,scientistsneededstatisticstoinfertheinteractionbetweengenesandtheproteinsthatregulatethemandtothenmathematicallydescribethisnetwork'sunderlyingstructure-thedynamicpatternofgeneandproteinactivityovertime.Butphysicistswhodidnotworkwithparticles(orplanets,forthatmatter)viewedstatisticsasnothingshortofananathema."Ifyourexperimentrequiresstatistics,"BritishphysicistErnestRutherfordoncesaid,"yououghttohavedoneabetterexperiment."EButinworkingwithmicroarrays,"theexperimenthasbeendonewithoutyou,"Wigginsexplains."Andbiologydoesn'thandyouamodeltomakesenseofthedata."Evenmorechallenging,buildingblocksthatmakeupDNA,RNAandproteinsareassembledinmyriadways;subtlydifferentrulessubtlydifferentrulesofinteractiongoverntheiractivity,makingitdifficult,ifnotimpossible,reducetheirpatternsofinteractiontofundamentallaws.Somegenesandproteinsarenotevenknown."Youaretryingtofindsomethingcompellingaboutthenaturalworldinacontextwhereyoudon'tknowverymuch,"saysWilliamBialek,abiophysicistatPrincetonUniversity."You'reforcedtobeagnostic."Wigginsbelievesthatmanymachine-learningalgorithmsperformwellunderpreciselytheseconditions.Whenworkingwithsomanyunknownvariables,"machinelearningletsthedatadecidewhat'sworthlookingat,"hesays.FAttheKavliInstitute,Wigginsbeganbuildingamodelofageneregulatorynetworkinyeast-thesetofrulesbywhichgenesandregulatorscollectivelyorchestratehowvigorouslyDNAistranscribedintomRNA.Asheworkedwithdifferentalgorithms,hestartedtoattenddiscussionsongeneregulationledbyChristinaLeslie,whoranthecomputationalbiologygroupatColumbiaatthetime.Lesliesuggestedusingaspecificmachine-learningtoolcalledaclassifier.Saythealgorithmmustdiscriminatebetweenpicturesthathavebicyclesinthemandpicturesthatdonot.Aclassifiersiftsthroughlabeledexamplesandmeasureseverythingitcanaboutthem,graduallylearningthedecisionrulesthatgovernthegrouping.Fromtheserules,thealgorithmgeneratesamodelthatcandeterminewhetherornotnewpictureshavebikesinthem.Ingeneregulatorynetworks,thelearningtaskbecomestheproblemofpredictingwhethergenesincreaseordecreasetheirprotein-makingactivity.GThealgorithmthatWigginsandLesliebeganbuildinginthefallof2002wastrainedontheDNAsequencesandmRNAlevelsofregulatorsexpressedduringarangeofconditionsinyeast-whentheyeastwascold,hot,starved,andsoon.Specifically,thisalgorithm-MEDUSA(formotifelementdiscriminationusingsequenceagglomeration)—scanseverypossiblepairingbetweenasetofDNApromotersequences,calledmotifs,andregulators.Then,muchlikeachildmightmatchalistofwordswiththeirdefinitionsbydrawingalinebetweenthetwo,MEDUSAfindsthepairingthatbestimprovesthefitbetweenthemodelandthedataittriestoemulate.(Wigginsreferstothesepairingsasedges.)EachtimeMEDUSAfindsapairing,itupdatesthemodelbyaddinganewruletoguideitssearchforthenextpairing.Itthendeterminesthestrengthofeachpairingbyhowwelltheruleimprovestheexistingmodel.ThehierarchyofnumbersenablesWigginsandhiscolleaguestodeterminewhichpairingsaremoreimportantthanothersandhowtheycancollectivelyinfluencetheactivityofeachoftheyeast's6,200genes.Byaddingonepairingatatime,MEDUSAcanpredictwhichgenesratchetuptheirRNAproductionorclampthatproductiondown,aswellasrevealthecollectivemechanismsthatorchestrateanorganism'stranscriptionallogic.Thereadingpassagehassevenparagraphs,A-ChoosethecorrectheadingforparagraphsA-GfromthelistWritethecorrectnumber,i-x,inboxes1-6onyouranswerListofThesearchforthebetter-fitmatchingbetweenthemodelandthegainedfigurestoforeseetheactivitiesofthegenesThedefinitionofAflashbackofacommencementforAflashbackofacommencementforafar-reachingAdrawingofthegeneAnalgorithmusedtoconstructaspecificmodeltodiscerntheappearanceofsomethingnewbythejointeffortofWigginsandanotherscientistAnintroductionofabackgroundtracingbacktotheavailabilityofmaturetechniquesfordetailedresearchongenesAwayouttofacethechallengeconfrontingthescientistonthedecidingofresearchableAfailuretofindoutsomespecificgenescontrollingtheproductionofcertainTheuseofameansfromanotherdomainforAtoughhurdleonthewaytofindthelawgoverningtheactivitiesofthegenesExample:ParagraphAiiiDothefollowingstatementsagreewiththeinformationgiveninReadingPassage1?Inboxes7-9onyouranswersheet,writeTRUEifthestatementistrueFALSEifthestatementisfalseNOTGIVENiftheinformationisnotgivenintheWigginsisthefirstmantouseDNAmicroarraysfortheresearchonThereisalmostnopossibilityfortheefforttodecreasethepatternsofinteractionbetweenDNA,RNAandproteins.WigginsholdsaverypositiveattitudeonthefutureofgeneticCompletethefollowingsummaryoftheparagraphsofReadingPassage,usingNoMorethanThreewordsfromtheReadingPassageforeachanswer.Writeyouranswersinboxes10-13onyouranswersheet.Wigginsstatesthattheastoundinglyrapiddevelopmentoftechniquesconcerningthecomponentsofgenesarousedtheresearcherstolookat10 fromatotallynewway.11 istheheartandsoulofthesetechniquesandnomatterwhatthe12 were,atthesametimetheycanofferawholepictureofthegenes'activitiesaswellas13 inalltypesofcells.Withtheseofthe123x45v6i7NOT89NOTDNA123x45v6i7NOT89NOTDNA(myriad)theirexpressionFlightfromMobilesarebarred,butpassengerscanlapawayontheirlaptopstotheirhearts’content.IsonereallysaferthanFlightfromMobilesarebarred,butpassengerscanlapawayontheirlaptopstotheirhearts’content.Isonereallysaferthantheother?IntheUS,aCongressionalsubcommitteegrilledairlinerepresentativesmayindeedposeariskalbeitaslightone.ThiswouldseemtovindicatethetreatmentofManchesteroilworkerNeilWhitehouse,whowassentencedlastsummertoayearinjailbyaBritishcourtforrefusingtoturnoffhismobilephoneonaflighthomefromMadrid.Althoughhewasonlytypingamessagetobesentonlandingnotactuallymakingacall,thecourtdecidedthathemsputtingtheflightatrisk.Thepotentialforproblemsiscertainlythere.Modernairlinersarepackedwithelectronicdevicesthatcontroltheplaneandhandlenavigationandcommunications.Eachhastomeetstringentsafeguardstomakesureitdoesn'temitradiationthatwouldinterferewithotherdevicesintheplane-standardsthatpassengers'personalelectronicdevicesdon'tnecessarilymeet.Emissionsfrominsidetheplanecouldalsointerferewithsensitiveantennaeonthefixedexterior.Butdespiterunninganumberofstudies,Boeing,Airbusandvariousgovernmentagencieshaven'tbeenabletofindclearevidenceofproblemscausedbypersonalelectronicdevices,includingmobilephones."We'vedoneourownstudies.We'vefoundcellphonesactuallyhavenoimpactonthenavigationsystem,"saysMaryanneGreczyn,aspokeswomanforAirbusIndustriesofNorthAmericainHerndon,Virginia,Notdotheyaffectothercriticalsystems,shesaysTheonlyimpactAirbusfound?"Sometimeswhenapassengerisstartingorfinishingaphonecall,thepilothearsawryslightbeepintheheadset,"shesays.ThebestevidenceyetofaproblemcomesfromareportreleasedthisyearbyBritain'sCivilAviationAuthority.ItsresearchersgeneratedsimulatedcellphonetransmissionsinsidetwoBoeingaircraft.Theyconcludedthatthetransmissionscouldcreatesignalsatapowerandfrequencythatwouldnotaffectthelatestequipment,butexceededthesafetythresholdestablishedin1984andmightthereforeaffectsomeoftheolderequipmentonboard.Thisdoesn’tmean"missioncritical"equipmentsuchasthenavigationsystemandflightcontrols.Butthedevicesthatcouldbeaffected,suchassmokedetectorsandfuellevelindicators,couldstillcreateseriousproblemsfortheflightcrewiftheymalfunction.Manyplanesstilluseequipmentcertifiedtotheolderstandards,saysDanHawkes,headofavionicsattheCAA'sSafelyRegulationCroup.TheCAAstudydoesn'tprovetheequipmentwillactuallyfailwhensubjectedtothesignals,butdocsshowthere'sadanger."We'vetakensomeoftheuncertaintyoutofthesebeliefs,"hesaysAnotherstudylaterthisyearwillseeifthecellphonesignalsactuallycausedevicestofail.In1996,RTCA,aconsultanthiredbytheFederalAviationAdministrationintheUStoconducttests,determinedthatpotentialproblemsfrompersonalelectronicdeviceswere"low".Nevertheless,itrecommendedabanontheiruseduring"critical"periodsofflight,suchastake-offandlanding.RTCAdidn'tactuallytestcellphones,butneverthelessrecommendedtheirwholesalebanonflights,Butif"bettersafethansorry"isthecurrentpolicy,it'sappliedinconsistently,accordingtoMarshallCross,thechairmanofMegaWaveCorporation,basedinBoylston,Massachusetts.Whycellphonesoutlawedwhennooneconsidersabanonlaptops?“It'slikemostthingsinlife.ABCDEreasonisalittlebittechnical,reasonisalittlebittechnical,alittlebiteconomicandalittlebitpolitical,”saysThecompanywroteareportfortheFAAin1998sayingitispossibletobuildanon-boardsystemthatcandetectdangeroussignalsfromelectronicdevices.ButCross'spersonalconclusionisthatmobilephonesaren'ttherealthreat."You'dhavetostretchthingsprettyfartofigureouthowacellphonecouldinterferewithaplane'ssystems,"hesays.Cellphonestransmitinrangesofaround400,800or1800megahertz.Sincenoimportantpieceofaircraftequipmentoperatesatthosefrequencies,thepossibilityofinterferenceisverylow,Crosssays.TheuseofComputersandelectronicgamesystemsismuchmoreworrying,liesays.Theycangenerateverystrongsignalsatfrequenciesthatcouldinterferewithplaneelectronics,especiallyifamouseisattached{thewireoperatesasanantennaoriftheirbuilt-inshieldingissomehowdamaged.Someairlinesareevenplanningtoputsocketsforlaptopsinseatbacks.There'sfairlyconvincinganecdotalevidencethatsomepersonalelectronicdeviceshaveinterferedtheproblemdowntoapassenger'sportablecomputer.Theycouldactuallywatchtheautopilotdisconnectwhentheyswitchedthecomputeron.Boeingboughtthecomputer,tookittotheairline'slabsandeventesteditonanemptyflight.Butaswitheveryotherreportedinstanceofinterference,technicianswereunabletoreplicatetheproblem.Someengineers,however,suchasBruceDonhamofBoeing,saythatcommonsensesuggestsphonesaremoreriskythanlaptops."Adevicecapableofproducingastrongemissionisnotassafeasadevicewhichdoesnothaveanyintentionalemission,"liesays.Nevertheless,manyexpertsthinkit'sillogicalthatcellphonesareprohibitedwhencomputersaren't.Besides,theproblemismorecomplicatedthansimplylookingatpowerandfrequency.Intheair,theplaneoperatesinasoupofelectronicemissions,createdbyitsownelectronicsandbyground-basedradiation.Electronicdevicesinthecabin-especiallythoseemittingastrongsignal-canbehaveunpredictably,reinforcingothersignals,forinstance,orcreatingunforeseenharmonicsth