托福必备科学美国人101Word格式.docx
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托福必备科学美国人101Word格式.docx
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Biologistsbelievethatsexoffersanevolutionaryadvantagebecauseitpromotesgeneticdiversity.Comingupwithfreshnewgenecombinationsshouldalloworganismstooutsmartparasites,whicharealsocontinuouslyevolving.Butifthattheoryiscorrectthenbdelloidrotifers,freshwaterinvertebratesthathaven’thadsexinatleast30millionyears,shouldhavebeenparasitedintoextinctionlongago.Yetheretheyare,aliveandwell.
Tofindoutwhy,scientistsinfectedrotiferswithadeadlyfungus.Andtheyfoundthatbdelloidrotiferscanshaketheinfectionbydryingout,driftingawayandthenrehydratingoncetheylandsomeplacemoistbutfungus-free.Thefungidon’tsurvivethedesiccation,sothelongerthebdelloidsstaydry,thebetterofftheybe.
Soforcelibaterotifersthatwanttostayclean,agoodlongdryspellisjustwhatthedoctorordered.
—KarenHopkin
Imagineaworldwithlevitatingcars,MRIsthesizeoflaptops,andwidescaleefficientenergydistribution.ThesemightnotbepipedreamsifscientistscancapitalizeonafindinginthejournalNature.Superconductorscarryelectricitywithnolosstoresistance.Theyaretoregularconductorswhatalaserbeamistoalightbulb.Theproblemistheyhavetobecooledtoatleast–100degreesCelsiustowork.Thentheelectronsspontaneouslystartmovinginonedirectionandformingpairs.Andnow,scientistshavecaughtaglimpseofamysteriousphasetheycallthe“pseudo-gap”wheretheelectronslineupjustbeforetheyformpairsandstartsuperconducting.LouisTailleferfromtheUniversityofSherbrookesaidtheyusedamagneticfieldtoaligntheelectronflow:
“Theeffectwasverybig.Itwassurprisinglybig.”Ifscientistscantakeadvantageofthiseffect,roomtemperaturesuperconductorscouldbeastepcloser.“Ifwedofindorifwedoarriveatamaterialthatcansustainsuperconductivityatroomtemperaturewewillhaveahugetechnologicalrevolution,similaronascaletothetransistor.”
—SonyaBuyting
ListeningWhileDrivingIs,What'
dYaSay?
Weallknowthattalkingonacellphonecanimpairourabilitytodrive(althoughtoomanyofusdoitanyway).NowastudyinthejournalPsychonomicBulletinandReviewshowsthatthereverseisalsotrue:
drivingmakesithardtokeeptrackofwhatwe’retalkingabout.
Previousstudieshadfoundthatmotoristsareabletoconversejustfine.ButtoGaryDelloftheUniversityofIllinoisthatfindingjustdidn’tmakesense.Becausecomprehendingspeechrequiresattention,asdoessteeringthefamilysedan.SoDelldidastudyinadrivingsimulator.
Ninety-sixparticipantswerepairedup,withonetakingthewheelwhiletheothersatinthepassengerseatortalkedtothedriveronahands-freephone.Eachparticipantlistenedtoandwasaskedtorepeatahandfulofstories,andthentorememberthemaftergettingoutofthecar.Asyoucanimagine,thedrivershadatoughertimerecallingthedetailsthanthepassengers.AndtheirconversationalskillstookthebiggestnosedivewhiletheyweretryingtonavigateintersectionsorhandletrafficNext,maybethescientistswilldeterminewhetherdrivingalsoimpairsourabilitytosing,eatbreakfast,andputonmakeup.And,ofcourse,text.
Cleopatra'
sEyeliner:
PeeperHealthKeeper
WhenyoupictureancientEgyptianbeautiessuchasQueenNefertitiorCleopatra,they’reprobablywearingdramaticblackeyeliner.AncientEgyptiansbelievedthateyemakeuphadpropertiesbestowedbythegodsprotectedthewearersfromillness.Modernscientistsdeterminedthatthemakeupcontainsoften-harmfullead,sotheydiscountedanybeneficialeffects.ButaccordingtoresearchpublishedinthejournalAnalyticalChemistry,theeyemakeupmayindeedhavepreventeddisease.
Scientistsanalyzed52differentsamplesfromancientEgyptianmakeupfoundattheLouvre.Theyidentifiedfourdifferentlead-basedsubstances,twoofwhichwereman-made,notnatural.Theythenappliedthesubstancestoacultureofhumancells.Andthecellsexperienceda240percentincreaseintheproductionofnitricoxide,whichisknowntojumpstarttheimmunesystem.
TheancientmarshyNilewouldhavehostedmanyeyedisease–causingbacteria.Applicationofthemakeupmayhaverevvedupcells’immunityandprotectedagainstinfection.Thechemicalcompoundswerenodoubtusedinitiallybasedonappearance.Butthenwearersnoticedtheyweren’tgettingeyeinfections.Thegodsgotpraised,butitwasancientchemistswhodeservedthecredit.
—CynthiaGraber
FrenchFriesontheCornySide
EverwonderwhatyourFrenchfrieswerefriedin?
Likebumblingburglarswholeavefingerprintsatacrimescene,cookingoilsleavetheirownclues.AndbymeasuringthecarbonisotopesinFrenchfries,UniversityofHawaiiresearchersfoundthatoneoiltopsallothersasthechoicetofryfriesin:
cornoil.That’saccordingtoareportintheProceedingsoftheNationalAcademyofSciences.
Nationalchainrestaurantstypicallyrevealonlythatfriesmaycontainoneormoreofthefollowingoils:
corn,canola,soybean,cottonseed,sunflowerandpalm.Butconsumersmightlikealittlemoreinfo:
inamealofburger,friesandsoda,20percentofthetotalcaloriescomefromtheoilthatfriedthepotatoes.
Analyzingfriesfromnearly200Hawaiianrestaurants,thescientistsfoundthat69percentofthenationalchainoutletsusedcornoil,comparedwithjust20percentofindependenteateries.
Cornoilisprobablytheleasthealthyoftheoilsmentioned,withmoreharmfulsaturatedfatsthancanolaorsunflowerandfewerheart-healthycompoundsthansoybean.Ofcourse,regardlessofwhatthey’refriedin,Frenchfriesprobablyaren’tonyourdiet.Thenagain,you’reprobablynotonyourdieteither.
ArtificialMuscleBringsBackBlink
Mostofusblinkwithoutthinking.Butpeoplewho’vesustainedstrokesorcombatinjuriescanlosetheirabilitytoblink.Whichisimportantforlubricatingandcleaningtheeye.Surgeryisanoption—asmallpieceofmuscletransplantedfromthelegcansometimeswork.Buttheoperationtakes10hoursandhasitsowndangers.SoscientistsattheUniversityofCalifornia,Davis,MedicalCenteraredevelopingartificialmusclestohelppatientsblinkagain,workdiscussedintheArchivesofFacialPlasticSurgery.
Theblinksystemstartswithwhatresearcherscallaneyelidsling,asmallpieceofmuscleorfabricthatholdstheeyelid.Theslingattachestobonearoundtheeye.It’sthenlinkedtoanelectrostaticpolymer—basicallyapieceofflexibleplasticthatexpandsorcontractsviavoltagechange.Atinybatteryhiddeninanaturalhollowinthetemplepowersthepolymer.Electricalcurrentkeepsthemusclescontractedandtheeyesopen.Killthecurrentandthelidcloses.
Here’sthecreepypart—themechanism’sbeentestedoncadavers,whichareblinkingaway.Butnowthattheprincipleisproven,inthenextyearsrealpatientscouldbeonthebrinkofablink.—CynthiaGraber
RunningShoesJogJoints
Yourfeetmayloverunningshoes.Butwhatabouttherestofyourbody?
Newresearchfindsthatrunningshoesactuallyincreasethepressureonankles,kneesandhips—morethanhighheelscanduringwalking.That’saccordingtoastudyintheJournalofInjury,FunctionandRehabilitation.
Researchersenlisted68injury-freerunnerswhonormallyloggedatleast15milesaweek.Thesubjectsranattheirownpaceonatreadmill,firstinmodernrunningshoesandthenagainbarefoot.Itturnsoutthatrunningshoesuppedthepressure,ortorque,onkneejointsby38percentoverbarefeet.Hipsexperiencedapressureincreaseof54percent.Walkingininch-and-a-halfhighstilettosonlyworsenedkneetorquebyabout20percentinpreviousstudies.
Sincestressfuljointpressurecancauseosteoarthritis,shouldrunnersstarthittingthepavementinbarefeet?
Probablynot.True,someelitemarathonersdorunsanssneakers.Butapparentlylettingtherubberhittheroadislikevariousspiritualrituals:
toughonthebody,butgoodforthesole.
—MollyWebster
WhyDwarfGalaxiesLackStarPower
Forastronomerswhostudythelarge-scalestructureoftheuniverse,dwarfgalaxieshaveprovenquitevexing.Becausetheleadingmodelofcosmologyhasbeenunabletoaccountfortheirrelativelackofsubstance.NowscientistswritinginthejournalNatureshowthatthecurrentmodelcanactuallygeneratedwarfgalaxiesjustfine.Youjustneedtolookatthestars.
Therearetwotypesofmatterintheuniverse:
ordinarymatter,includingthematerialthatmakesupstars.Anddarkmatter:
thatmysteriousstuffwecan’tseebutthatclearlyaffectsordinarymatter.It’sthepresenceofcolddarkmatterthatexplainshowtheyounguniversewentfrombeingsmoothtobeinglumpy,asordinarymattercoalescedfirstintostarsandthenintogalaxies.Theproblemisthatdwarfgalaxiesarenotasdenseasthecolddarkmattermodelsaystheyshouldbe.
Nowaninternationalteamofastronomerssaysyoucanblamegustsofstellarwind.Becauseintheroilingcauldronofactivitythatgovernsgalaxyformation,somestarsgosupernova.Thosespectacularexplosionsliterallyblowmatteraway,andyou’releftwithadwarfgalaxythat’salotlikemostindependentfilms:
abitlightonstars.
DoAllAnimalsSoundtheSame?
Whatdoawhaleandafroghaveincommon?
AccordingtoastudypublishedintheProceedingsofthe
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