60 second science听力原文.docx
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60 second science听力原文.docx
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60secondscience听力原文
1、BacteriaUseArsenicAsBasicBuildingBlockInAPinch
Abacteriumhasbeendiscoveredthatcansubstitutearsenicforphosphorusinfundamentallifechemistry.ChristopherIntagliatareports.
Lifeonearthrequiressixbasicingredients—carbon,hydrogen,nitrogen,oxygen,sulfurandphosphorus.ThosesixelementsarethebuildingblocksforDNAandRNA,alongwithproteinsandfats.Whichmeansthey'reessentialforlife—asweknowit.Butitmightbetimetoupdatethatlist.Becausescientistshavefoundabacteriumthatcandowithoutphosphorus—liveonarsenicinstead.
Theresearchershadahunchabuglikethismightexist,becausearsenichassomechemicalpropertiesincommonwithphosphorus.SotheycollectedmudfromCalifornia'sMonoLake,wherethewatersarenaturallysalty,andlacedwitharsenic.Backinthelab,theyculturedmicrobesfromthatmud.Butinsteadofaddingphosphorustotheculturestohelpthebugsgrow,theyaddedvaryinglevelsofarsenic.
Onebacterialstraincontinuedtothrive.AndtestsconfirmedthattheorganismscompensatedforthelackofphosphorusbybuildingtheirDNAwitharsenicinstead.TheresearchappearsinthejournalScience.[FelisaWolfe-Simonetal,ABacteriumThatCanGrowbyUsingArsenicInsteadofPhosphorus]
Thisisthefirstknownlifeformthatseemstobeabletoswapoutoneoflife'sfundamentalbuildingblockswithanotherelement.Soforastrobiologistshuntingforlifeinspace,don’truleoutplacesfilledwithpoison.
—ChristopherIntagliata
2、It'sEvenMoreFullofStars
ThediscoverythatellipticalgalaxieshavemanymorereddwarfstarsthantheMilkyWaymeansthattheuniversemighthavethreetimesasmanytotalstarsaspreviouslythought.CynthiaGraberreports
Tomanywhostareupattheheavens,thestarsmayseemsimplyuncountable.Ofcoursethat’snottheattitudeofastronomers.Butthey’vemadeadiscoverythatmeansthereareprobablyalotmorestarsintheuniversethantheythought.
Reddwarfsarestarsthatareonly10to20percentasmassiveasoursun.They’resofaintthatastronomersweren’tabletodetecttheminanygalaxiesotherthanourownMilkyWay,andneighboringones.
SoresearchersusedsensitiveinstrumentsattheKeckObservatoryinHawaii.Theyfoundfaintsignaturesofthesereddwarfstarsineightmassiveellipticalgalaxiesrelativelyclosetous—between50millionand300millionlight-yearsaway.Andtheydiscoveredthatthesegalaxieswerehometo20timesasmanyreddwarfsasthereareintheMilkyWay.
Thefindingmeansleadsastronomerstobelievethattheremaybethreetimesasmanystarsintheuniverseasthey’dpreviouslytheorized.TheresearchwaspublishedinthejournalNature.[PietervanDokkumandCharlieConroy,Asubstantialpopulationoflow-massstarsinluminousellipticalgalaxies]
AndarecentlydiscoveredexoplanetorbitingareddwarfhadsomeEarth-likequalities.LeadresearcherPietervanDokkumsaystherecouldbetrillionsofEarthsorbitingtheubiquitousreddwarfs.
—CynthiaGraber
3、AncientRainforestCollapseIncreasedReptileDiversity
Reptilesweretrappedinequatorialrainforests'fragmentsfollowingglobalwarming300millionyearsago,leadingtoanexplosionindiversity.SteveMirskyreports
TheNovember26thissueofthejournalScienceincludedastudyshowingthattheextinctionofthedinosaurssome65millionyearsagoallowedpunymammalstogetreallybig.Butwellbeforeallthathappened,anothereventtriggeredadifferentburstofevolutionaryactivity.
Anewstudyfindsthatabout300millionyearsago,thetropicalrainforestsalongtheequatorfellapart.Thefamiliarculprit—globalwarming.
Present-dayEuropeandNorthAmericawereontheequatorbackthen,andwerecoveredwithrainforests.Butglobalwarmingmadethingsevenhotteranddrier.
Theexpansiverainforestsbrokeupintosmallerfragments,andreptilepopulationsbecameisolatedfromeachotherinthefragments.Suchgeographicalisolationallowsdifferentpopulationstoevolveindifferentdirections,whichledtoagreatincreaseinreptilediversity.TheresearchappearsinthejournalGeology.[SardaSahney,MichaelBenton,andHowardFalcon-Lang,"RainforestcollapsetriggeredCarboniferoustetrapoddiversificationinEuramerica"]
Theexplosioninreptilesultimatelyledtotheevolutionofthedinosaurs,whichdominatedtheplanetuntiltheyfellvictimtothemassiveimpactthatallowedusmammalstotakeover.AsVonnegutwouldsay,soitgoes.
—SteveMirsky
4、UltramarathonersReveal"Safe"Injuries
Runnerswhoweretrackedina2,800-mileracerevealedthatsimplemuscleinflammationisokaytorunthroughbutjointinflammationisriskier.SteveMirskyreports
Forsomereason,everyyearafewdozenrunnersdashfromsouthernItalyallthewaytotheNorthCapeofNorway,inwhat’scalledtheTransEurope-Footrace.Ittakesabouttwomonthstocoverthealmost2,800miles,about45milesaday.
Inthe2009edition44ofthe66participantsallowedthemselvestobeexaminedmedicallythroughout.ThefindingswerepresentedNovember29thattheannualmeetingoftheRadiologicalSocietyofNorthAmericainChicago.Andsomeofthediscoveriesmaybeofusetothelessambitiousamongus.
Musclevolumeofthelegsactuallywentdown7percentbecauseoftheincredibleenergyconsumptionofthedailydistances.Andsomeleginjurieswerefoundtobesafetorunthrough.Itwasokaytokeepgoingwithsimplelegmuscleinflammation,forexample.Butotheroveruseinjuries,likejointinflammation,carriedagreaterriskofworsening.Runnerslost40percentoftheirbodyfatinthefirsthalfoftheraceand50percentaltogether.Beginningrunnerscanlikewiseexpecttoseearapidfatlossatfirst.AndyougettostopbeforereachingNorway.
—SteveMirsky
5、WritingExerciseHelpsFemalePhysicsStudents
Asimplewritingexercisethathadbeenshowntohelpminoritystudentsimprovetheirgradesalsoseemstohelpfemalephysicsstudents.CynthiaGraberreports
BackinApril2009,thispodcastcoveredresearchfindingthatasimplewritingexercisehelpedminoritystudentsimprovetheirgrades.Now,anewstudyshowsthatthesameexercisecanhelpfemalecollegestudentsovercomestereotypesaboutwomeninscienceandimprovetheirperformance.TheworkisinthejournalScience.[AkiraMiyakeetal.,ReducingtheGenderAchievementGapinCollegeScience:
AClassroomStudyofValuesAffirmation]
Womeninphysicsclassestendtodomorepoorlythanmenonexams.Theresearcherswantedtolookattheroleofpsychologicalissues.Theysurveyed399studentsofbothsexesinanintrophysicsclassaboutwhethertheyagreedwiththestereotypethatmenaregenerallybetteratphysics.
Thenhalftookpartinexerciseswheretheychosevaluesimportanttothem,andtheywroteaboutwhythesemattered.Theydidsoatthebeginningofthesemesterandagainbeforeamidtermexam.
Inthecontrolgroup—whichdidnotdothevalueswriting—menscoredmuchbetterontheexam.Butintheaffirmationgroup,womensawtheirgradesimprove,significantlyreducingthegendergap.Andwomenwhohadagreedthatmenwerebetteratphysicsimprovedthemost.Soalittlepositiveaffirmationmighthelpmorewomenthriveinscience—andstayinthefield.
—CynthiaGraber
6、OnThanksgiving,SmallerPlatesforLargerPalates
Cornell'sBrianWansinknotesthatsmallerplatescanleadtosmallerfoodintakes,andhehasmoreholidayeatingtips.SteveMirskyreports
AsweinapproachtheThanksgivingholiday,onemajorquestionloomslargeformillionsoflargeAmericans:
Aremyfatpantsfatenough?
Thanksgivingmarksthestartoftheholidayseasonfoodfest,asix-weekstretchwhendietsandbeltswillbeseverelystrained.Sowhatcanbedonetokeepthegluttonyundersomethingresemblingcontrol?
BrianWansinkdirectstheCornellUniversityFoodandBrandLabandistheauthorofthebook"MindlessEating:
WhyWeEatMoreThanWeThink".Hisresearchhasrevealedthatsimplyservingfoodona10-inchplateratherthana12-inchplatecouldleadtoamorethan20percentreductionincalories,withthemealstillbeingsatisfying.Healsofoundthatevenotherfoodresearchersatemorethanhalfagainasmuchicecreamiftheyservedthemselveswithbigbowlsandbigscoopsversussmallerbowlsandscoops.
YoucancatchWansink'stipsbeyondthesmallerplateinavideofortheFoodInsightBlog,atButashetoldPreventionmagazine,ifthere’sonedayallyearforsomeguilt-freeindulgence,Thanksgivingisit.
—SteveMirsky
7、ExercisingtoMusicKeepsElderlyUpright
Anexerciseprogramfeaturingmovingtomusichelpedsignificantlylowerthenumberoffallsinelderlypeople.CynthiaGraberreports
Theelderlysufferfromanalarmingepidemic.Athirdofpeopleover65fallatleastonceayear.Halfofthosefallmorefrequently.Exercisecanhelp,especiallywhentheyexercisetothis[soundofpiano].That’sright,theelderlygainabettersenseofbalancewhentheyexercisetopianomusic.TheresearchwaspublishedonlineintheArchivesofInternalMedicine.[AndreaTrombettietal.,"EffectofMusic-BasedMultitaskTrainingonGait,Balance,andFallRiskinElderlyPeople"]
ScientistsinSwitzerlandrecruited134adults—averageageabout75.Forsixmonths,halftookaweeklyhour-longclassthatfocusedonbalance.Theyworkedouttothepiano,changingmovementsinresponsetochangesinthebeat.Theexercisesgotprogressivelymoredifficult.Theothergroupcontinuedwiththeirregularactivitiesforsixmonths.
Thenthetwogroupsswitched.Thosewhoworkedouttotunesimprovedtheirgaitandhadlongerandmorestablestrides.Overall,thefirstmusic-exercisinggroupe
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