听写必备上半年SSS文本全集听写必备Word文档下载推荐.docx
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60-SecondScience.I'
mSteveMirsky.Gotaminute?
HappyNewYear!
Anddon’tfeelbadabouttakingtodayoff.Afterall,you’vetraveledfar.AndI’mnottalkingaboutthetriphomefromthepartylastnight.AccordingtoNASA,justbybeingontheplanetEarthinthelastyear,you’vezippedabout584millionmilesaroundthesuntogetbackwhereyouwere.Atanaveragespeedofabout67,000milesperhour.Again,nottalkingaboutthedrivehomelastnight.
Ofcourse,thetripwasnotaperfectcircle.AsKeplershowed,theEarth’sorbitisanellipse,withthesunatoneofthetwofocalpoints.Healsofiguredouttheplanetgoesfasterwhenit’satperihelion,nearerthesun,thanwhenit’sataphelion,itsfarthestdistance—whichwouldexplainwhysummerseemstozipby,excepttheseasonsareafunctionofthetiltoftheEarth’saxis,notitsdifferentdistancesfromthesun.AndtheEarthrotated365andaquartertimesduringitssweeparoundthesun.Thetriptook8,766hours.Or31,557,600seconds.Or525,960minutesjustlikethisone.
ThanksfortheminuteforScientificAmerican'
s60-SecondScience.I'
mSteveMirsky
SSS2009-01-02
mCynthiaGraber.Thiswilljusttakeaminute.
Mosquitoescarrynastydiseases—denguefever,westnile,malaria.Butthemicrobesthatcausethosediseasesdon’tattachthemselvestothemosquitoesandthenimmediatelylatchontotheirnextvictim.Theyneedtimetogrowandreplicateinthemosquitobeforemigratingtothebug’ssalivaryglands.Forexample,thedenguefevervirustakesabouttwoweekstoincubate.
SoresearchersfromtheUniversityofQueenslandinAustraliaandCentralChinaNormalUniversityarelookingatawaytoshortenthelivesofmosquitoes—andthuscurtailtheirdisease-transmittingability.
ResearchersworkedwithabacterialparasitecalledWolbachiathatinfectsnumerousinsectspecies.TheyspentthreeyearsadaptingittoinfecttheAedesaegypti
mosquito,whichcarriesdenguefever.Itcutthelivesofthemosquitoesbymorethanhalf.ThoseresultswerereportedintheJanuary2ndissueofthejournalScience.ThescientistssaythatbecauseWolbachiashortensamosquito’slife,theinsectsarethatmuchlesslikelytopassonthediseasestheycarry.Soarelativelyinexpensiveandeffectivehumandiseasepreventionprogramcouldbetomass-infectmosquitoeswithWolbachia.Whichshouldmakethemedicalcommunitybuzz.
mCynthiaGraber.
SSS2009-01-05
.Gotaminute?
WeresidentsoftheMilkyWayshouldhavealittleextraskipinoursteptoday.Turnsoutourhomegalaxyismuchbiggerandmovingalotfasterthanwepreviouslythought.That’swhatresearchersfromtheHarvard–SmithsonianCenterforAstrophysicsreportedJanuary5thatthemeetingoftheAmericanAstronomicalSociety.
Olderstudiesofourgalaxy’sstructureandmotionusedindirectmeasurements.Butwecannowuseradiotelescopestodirectlyobservecertainfeaturesofthegalaxywhenwe’reinverydifferentplacesinourorbitaroundthesun.Andusingtraditionalsurveyingmethods,suchastriangulation,researcherscameupwiththenewfigures.
First,we’removingabout600,000milesperhourinourgalacticorbit,alotzippierthantheoldestimateof500,000.AndtheMilkyWay’stotalmassisabouthalfagainasmuchasweusedtothink.Whichmeanswe’reaboutasmassiveasthenearbyAndromedaGalaxy.TheMilkyWay’sbiggermassdoesmeanagreaterchanceofagravity-drivencollisionwithAndromeda.Butifthatclashoccurs,atleastnowwe’reinthesameweight-class.
mSteveMirsky.
SSS2009-01-06
Tuneineveryweekdayforquickreportsandcommentariesontheworldofscience--it'
lljusttakeaminute.
AstudypresentedatthemeetingoftheAmericanAstronomicalSocietyfindsthatthedebrissurroundingwhitedwarfstarsissimilartothecontentofrockyplanets--whichmeansthatrockyplanetscouldbecommontostarslikeoursun.CynthiaGraberreports.
SSS2009-01-06
Ifwewanttolearnmoreaboutourplanetandotherplanetsintheuniverse,wecangetsomehelpfromstarsthatarelongdeadandgone.That’swhatU.C.L.A.’sMichaelJurasaidattheAmericanAstronomicalSocietymeetingJanuary5th.HisteamusedobservationsfromNASA’sSpitzerSpaceTelescopetoinvestigatedeadwhitedwarfstars.
Dustanddebrisswirlaroundyoungstars.Thepiecesclumptogethertoformasteroidsandbiggerplanets.Whenastarlikeoursunfinallydies,itblowsitselfup,brightred.Thenitshrinksdownintoas