The Evolution and Explosion of Massive Stars
6
pages
English
Documents
Le téléchargement nécessite un accès à la bibliothèque YouScribe Tout savoir sur nos offres
6
pages
English
Ebook
Le téléchargement nécessite un accès à la bibliothèque YouScribe Tout savoir sur nos offres
The Evolution and Explosion of Massive Stars S.E. Woosley∗ and A. Heger† Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 T.A. Weaver Lawrence Livermore National Laboratory, Livermore, CA 94551 (Dated: August 2, 2002) Like all true stars, massive stars are gravitationally confined thermonuclear reactors whose com- position evolves as energy is lost to radiation and neutrinos. Unlike lower mass stars (M <∼ 8 M¯) however, no point is ever reached where a massive star can be fully supported by electron degen- eracy.
Voir
- silicon burning
- convective core
- helium core
- mass loss
- massive stars
- evolution
- star
- ions
- hydrogen
- helium
RationaleoftheTest
SAMPLEQUESTIONSFORENGLISHPROFICIENCYTESTFORCLASSX
Thetestistextindependenti.e.itisnotbasedonasettextorsyllabus.AsaProficiencyTest,ittestsbothskillsandknowledge.Thereisabalancebetweenkeyaspectsoflanguage–as,forinstance,readingskills,involvinglanguageknowledgeaswellasabilitytoprocessmeaningsthroughinference,analysis,comparisonandevaluation;knowledgeofgrammarandvocabularytotheextentthatisrequiredforgeneralcommunicativetasks.Specificskillsinvolvedinwritingarealsoimportante.g.awarenessofthestructureofsimplewrittentexts,howtheyareorganized,andthekindsofformatsthatareused‐inletters,forinstance.
Readingisgiven30marksasitisthebasisforgrammar&writingandbecauseitisimportantinfurtherstudieswhichstudentshavetoundertakeintheirlateracademicwork.Onepassageofreadingisofnarrativetype,(itmaybeanextractfromastory)andtestscandidates’understandingofevents,characters,descriptionsandalsotheperceptionofmeaningswhichareimplicitinthedetailsofthestory.Onepassageisanon‐fictionaltextcontaininginformation,argument,opinion,factsandideas.Readingofthiskindisfocusedonabilitytoarriveatthegistofanidea/argument,tocorrectlyseparateopinionsfromfacts(whichimpliessomeabilitytoanalyse),tobeabletodistinguishmainideasfromsubordinateones,tounderstandthetoneorviewpointe.g.humorous,ironic,seriousetc.Thethirdpassageisashortpoem,around20lines.Thisistotestifcandidatescanunderstandlanguagewhichiscomposeddifferently–itisnotlinear,hashiddenmeanings,unusualexpressionsandusessoundeffects(e.g.rhyme),simileandmetaphorwhichconveysmeaningindirectlyratherthandirectly.
Vocabularyisgiven20marksas:
1.Vocabularyiscentralinreadingcomprehension,whereitisessentialinmeaning.2.Itisalsotestedseparatelyinordertotestrangeofknowledgeofwords.Itistobekeptinmindthatthelevelofvocabularyissuchthatiscommonlyfoundintextsthatareprescribedintheschoolreadersatclass9and10.Grammar+Writing(30+20)TheMCQformatdoesnotallowtestingofwritingskillsaswritingisintegrativeofotherskillsandneedstobetestedthroughproduction.However,itisfeltthattheawarenessofthecomponentsofwritingcanbetestedhere ‐e.g.formatofletters,paragraphorganization,linkagebetweensentencesetc.Thesearealsopartoflanguageknowledge.ClozeTesthasbeenincludedasitisatestwhichisthemostglobalandcomprehensivetestoflanguage.Itconsistsofapassagewherethefirstsentencesetsthecontextofthepassageandsubsequentlythereareblanksatregularintervals.Fillingtheseblanksrequiresanoverallunderstandingofmeaningandofthelanguageitemsthatwillfitintotheparticularcontextofthesentences.Forexample,whentheuseofarticlesisexplainedinisolation,ausercannotunderstandwhereacertainarticleneedstobeused/omitted.Itisonlyincontextthatadecisionregardingtheuseofanarticleismade.Thereforeaclozetestisthebestwaytoknowifastudentcaninferfromthecontextwhetherthatarticleistobeusedornot.Thesameappliestootheritemslikeprepositions,conjunctionsetc.
Theformatandbreak‐upofpartsofthetestisasfollows:MaximumMarks:100Time:2.30Hours
Thequestionpapercontains100questions.Allquestionsarecompulsory.
Thequestionsaredividedintothefollowingparts:(Reading3passages)AUnseenPassage(Narrativetype)Q.1‐10BUnseenpassage(Informativetype)Q.11‐20CPoemQ.21‐30DVocabularyQ.31‐50EGrammarQ.51‐65FWritingQ.66‐85GClozeQ.86‐100 EachMultipleChoiceQuestionhasfouroptionsoutofwhichonlyONEoptioniscorrect.Eachcorrectanswerearnsacreditof1mark. Awronganswercarriesapenaltyof ‐¼mark. Anunansweredquestionearnsnomark.Instructionforwritingontheanswersheet:®UseonHBPenciltofilltheanswersheet.DONOTUSEAPen.®Ifyouwanttochangeanentryafterfillingabubble,erasethefilledbubble.ThefollowingexampleillustratesthecorrectwayofansweringaMultipleChoiceQuestion:Example:They’vebothworkedhereovertenyears.a.inb.forc.since
d.duringAnswer:Theanswertothisquestionis(b).YouhavetomarkitontheAnswersheetasshown:abcd DESCRIPTIONOFLEVELSOFPROFICIENCY:Thisisbeinggiveninordertodefinethelevelsofproficiencythatcorrelatewiththemarksobtainedinthetest.Ithelpsthecandidatetoseewhichareasneedmoreattentionforthedevelopmentofhigherlevelsofproficiency.5.GoodUser‐Hasoperationalcommandofthelanguage.Generallyhandlescomplexlanguagewellandunderstandsdetailedreasoning,reflectiveofacertaindegreeofanalyticalandinterpretativeskills.Hasarangeofvocabularyandcanunderstandcomplexstructures.Isawareofthestructureoforganizationandcoherenceintexts.Thisuserwillbeabletoscoreverywellinallpartsofthetest,particularlyinreadingcomprehensionandclozeexercise.(80%andabove)4.CompetentUser‐Hasgenerallyadequatecommandofthelanguagedespitesomeinaccuraciesandmisunderstandings.Understandssomeconventionsinwriting,andcaninterpretatext,knowsthestructures,butmaynothavearange.Thisuserwillbeabletoscorefairlywell,mayscorebetterinsomepartsofthetest.Performanceintheclozeexercisemaymakeadifference–betterperformanceinthispartbringsthecandidatetowardsthehigherendatthislevel.(60‐79%)3.ModestUser‐Haspartialcommandofthelanguage,copingwithoverallmeaninginmostsituations,thoughislikelytomakemanymistakesininterpretationandinunderstandingstructuresandwritingconventions.Shouldbeabletohandlebasiccommunicationreflectedinsomeknowledgeofgrammarandvocabulary.Thisuserwillmanageanaveragescoreinallpartsofthetest.(between40‐59%)2.LimitedUser‐Basiccompetenceislimited.Hasfrequentproblemsinunderstandingnon‐ factualinformation(thiswillshowupinreadingcomprehension)andwillnotbeabletoexerciseskillsneedinginferenceandinterpretation.Isnotabletouse&understandcomplexlanguage.Thisuserwillscorelowinreadingaswellasgrammarandcloze(willnot
understandtheoverallcoherenceofthepassage)andmaynotbeabletoanswerquestions
pertainingtotextorganization.(20‐39%)
1.ExtremelyLimitedUser‐Canunderstandonlyisolatedwords.Hasgreatdifficultyin
understandingstructures,butmaygivesomecorrectresponsestoquestionsofasimplerkind.
Maynotattempttoanswermanyofthequestions.Comprehensionlevelisverylowevenfor
simpletexts.(0‐19%)
SamplequestionsReadingComprehensionThisisasamplepassage(200words),shorterthantheonewhichwillappearinthetest(whichwillbeof300‐350words),butofthesamelevelofdifficulty.Inthesample,5MCQsaregiven.Intheactualpaper,therewillbe10MCQsoneachpassage(seeabove).Readthefollowingpassageandchoosethecorrectanswerforthequestions:Inthisworlditisnotonlyfutileforthesmalltoappealtoauthority,itisdangerousaswell.Fortunately,thetinyvoiceseldomreachesbigearsorwhoknowswhatmighthappen?WhenGafurreturnedhomefromthelandlord’sandquietlylaydown,hisfaceandeyeswereswollen.ThechiefcauseofsomuchsufferingwasMahesh.WhenGafurlefthomethatmorning,Maheshbrokeloosefromhistether,andenteringthegroundsofthelandlord,hadeatenupflowersandupsetthecorndryinginthesun.Whenfinallytheytriedtocatchhim,hehadhurtthelandlord’syoungestdaughterandhadescaped.Thiswasnotthefirsttimethishadhappened,butGafurwasforgivenbecausehewaspoor.Ifhehadcomearound,andasonotheroccasions,beggedforthelandlord’sforgiveness,hewouldprobablyhavebeenforgivenbutinsteadhehadclaimedthathepaidrent,andthathewasnobody’sslave.ThiswastoomuchforShibubabu,thelandlord,toswallow.Gafurhadbornethebeatingsandtortureswithoutprotest.Athome,too,helayinacornerwithoutaword.Hisheartburntwithinhimlikethesunoutside.Hekeptnocountofhowtimehadpassed.Q.1Inthepassage,whosevoiceisdescribedas`tiny’?a.Thevoiceofthebigpeopleb.Thevoiceofthesmallpeoplec.Thewrongpeopled.ThepeoplewhoarestrongQ.2WhywereGafur’seyesandfaceswollen?a.Hehadbeenbeatenbythelandlord.b.Hewasill.
c.Hewaslyingdown
d.HehadbeenhurtphysicallybyMahesh
Q.3WhydidGafurnotaskthelandlord’sforgiveness?
a.Hewaspoor.
b.Hedidn’tbotheraboutthelandlord.
c.Hewashappythatthelandlord’spropertyhadbeendamaged.
d.Hewantedtosavehisdignity
Q5.`Tokeepcountoftime’means:a.Tobeabletocountb.Tobeawareofthepassageoftimec.Tobeunconsciousd.TolookataclockVocabulary:1.Choosetheoptionclosestinmeaningtothewordinbold:Ancestora.oldb.forefatherc.pastd.dead2.Choosetheoptionoppositeinmeaningtothewordinbold:Exteriora.internalb.inferiorc.superiord.interiorGrammar:Choosetherightoptiontofillintheblank:1.What____________youliketodrink?a.willb.mightc.wouldd.shall2.Thereareotherpeopleinthepark_________ourselves.besidesb.besidec.befored.around3.Hehadaheartattack.Thedoctorwasimmediately___________.a.Sentoffb.sentforc.sentind.sentthroughWritingQ.1Thefollowingsentences(A‐E)canbeputtogethertoformawell‐connectedpassagebutarenotinthecorrectorder.Choosetheoptionthatgivesthebestorderofthesentences.A.Thentheywentbackintothecabin.B.Hisfatherwalkedintothelargebedroomtotherightofthekitchen.
C.Michaelwentintothelittleroomontheleft.
D.Theystoodinsilenceforafullfiveminutes.
E.Eachhungeredtoembracetheother,tocry,toscreamwithexcessofsorrow.
a.DACBEb.DEACBc.CBDEAd.CBEDAQ.2Readthefollowingandchoosetherightwordtoconnectthesentences:Theweatherofficehadpredictedthatitwouldrain_____1______.Theirpredictionsareusuallyaccurate.____2_____,itdidnotrainforseveraldays.When____3_____theraindidcome,itwasinsufficient___4______thecropsweredamaged.1.a.frequentlyb.muchc.soond.well2.a.howeverb.butc.thoughd.instead3.a.definitelyb.intheendc.atlastd.lastly4.a.andb.alsoc.evend.thatClozeClozetestisatestofgrammar,sentenceconnection,vocabularyetc.,withinacontext,andthereforeteststheoverallproficiencylevel.Thereisapassagewithblanksatregularintervalsandthecorrectchoicehastobeindicated.ThetestforclassXwillhaveoneclozetestof15questions,worth15marks.Thesamplegivenbelowisashortpassagewith5questions.MybrotherandIusedtofightagreatdealaschildren.Wedid__________ofthingstogether,notalwaysincomplete_______.Infact,ononeoccasion,heactually________myarm.Isupposehereallydidmea________,asImissedtheschoolexams______thatyear.Q.1a.manyb.somec.alotd.adeal
Q.2a.harmonyb.friendshipc.unisond.liking
Q.3a.damagedb.brokec.rippedd.tore
Q.4a.courtesyb.benefitc.favourd.privilege
Q.5a.forb.aroundc.atd.during
