简介:EDITOR’SNOTE:Longyearbyen,capitaloftheSvalbardIslands,entereditsannualprolongedperiodofdarknessonOctober9,2001.ThesunwasnotduetoriseagainuntilMarch8,2002.Duringthefive-month-longperiodofperpetualnight,peoplelivinginthenorthernmosthumansettlementseeonlystars,snowandice.Inthispartoftheworld,however,therearefourstudentsfromtheTibetAutonomousRegionjoint-ventureschool.
简介:Tosomeextent,China’ssecurityenvironmentdependsonifithasactivecreation,understanding,attentionandvigilanceonthecommoninterestsofthesurroundingareasandgroupsofstates,andifitcouldtaketimelyandpropercountermeasures.Inmypersonalview,twoprinciplesshouldbetakenintoconsideration.Thefirstprincipleisto
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简介:Inautumnof1946TseringWangdo,thenjust12yearsold,wenttoIndiatostudy.Thatwas60yearsagowhenIinterviewedhimin2006.Obviously,theyoungmanhasgonebuttheold
简介:Inordertoresearchsurfacecharacteristicsofliquidmetalwhichbasedonhydrodynamicstheoryandinteractionprinciplebetweenlaserwaveandsurfacetensionstationarywaveofliquidmetal,itisfinishedtoprovideanentirelytheoreticalequation,apparatusandtechniquesofthemeasuringthesurfacetensionforliquidmetalathightemperature.Thisapparatusisanautomaticmeasuringsystemforinformationcollectingandprocessing,inwhichacomputerisattachedtochargecoupleddevice,drivingcircuitsandA/Dconverter.ApplyingthenewapparatusthesurfacetensionvaluesofSn-Pbbasedbinaryandternaryalloysoldershavebeenobtainedonthebasisoftheabovework.TheexperimentalresultsindicatethatthesurfacetensionvaluesofliquidmetalSn-Pbbasedsoldersaredecreasedby37.3%and31.9%respectively.When1%ofBiorInisaddedinthesolders,theelementsBiandInhaveevidentsurfaceactivityinSn-Pbbasedsoldersandthewettabilityofthesoldersinincreasedwithincreasingsurfaceactivity.
简介:InordertocompareandevaluatethreeanimalmodelsforstudyingthepathogenicityofStaphylococcusepidermidisstrains,threeexperimentalanimalmodels,namely,murineintra-venousLD50,mouseforeignbodyinfectionandratcentralvenouscatheter(CVC)infectionmodelswereusedtoassesstherelativevirulenceoftwoS.epidermidisstrains,ATCC12228and97-337.Theresultsfromthreeanimalmodelswerecomparable,indicatingS.epidermidis97-337wasmorevirulentthanstrainATCC12228.TheratCVCinfectionmodelbestmimickedtheconditionsofclinicalpatientswithintmvenonscatheters,andmoreinformationcouldbeobtainedfromthismodel.Weconcludethatdifferentinvivomodelsservefordif-ferentpurposes,andtheratCVCinfectionmodelismostsuitableforstudyingspecificcharacteristicsofcatheterrelatedinfectionscausedbyS.epidermidisstratus.
简介:Gainingathoroughunderstandingofthetheoreticalprinciplesofrockbreakingwithadisccutterisacriticalissueintunnelboringmachine(TBM)technology.Tofullyconsiderthecomplexityandimportanceofthebasicprinciplesofrockbreakingduringtunnelexcavation,inthispaperweuseanewmethod,thesmoothparticlehydrodynamics(SPH),tostudytherock-breakingmechanismandverifyitsaccuracyandfeasibility.UsingtheSPHmethod,weinducetherockfragmentationprocesswithtwocuttersinsynchronousandsequentialorders.Theresultsshowthatwhenthecuttersactonrocksequentially,thesecondindentationinfluencesthecrackevolutionofthefirstindentation.Withincreasedcutterspacing,thesecondcrackgraduallybecomesindependentofthefirstcrack.Undersynchronousactionofthetwocutters,abursiformnucleusisgeneratedbeneaththecuttersandtheareaofthenucleusincreaseswithincreasedcutterspacing.Whetherthecuttersactontherocksequentiallyorsynchronously,wefoundtheoptimumcutterspacingofourchosenrocktypetobe60mm.Ouranalysesresultsshowthattheefficiencyofsequentialrockcuttingissuperiortosynchronouscutting,bothwithrespecttocrackevolutionandcutterforce.
简介:Theskyradianceanddegreeofpolarizationwithmultiplescatteringprocessconsideredwerecalculatedinthispaperbysolvingvectorformradiativetransferequationiteratively.Numericalexperimentforsimultaneouslyretrivingthesizedistribution(SD)andthecomplexrefractiveindex(CRI)ofaerosolparticlewasconductedwiththedegreeofpolarizationofskylight(DPS)andthelibrarymethodused.ItisshownfromtheresultsthattherealpartofCRIisalwayssensitivetoDPS.ButsituationissomewhatcomplicatedfortheimaginarypartofCRI.Therefore,itisexpectedthattherealpartofCRIcanberetrievedfromDPSanditsimaginarypartshouldberetrievedastheparticleislargeinsize.Inthispaper,sevensetsofDPSmeasurementson6January,1990inBeijingweregivenandtheopticalcharacteristicsofaerosolwereretrieved.
简介:Hearingloss(HL)isoneofthemostwidespreadsensorydisorders,affectingapproximately1in500newborns.HeritablediseasesoftheinnereararetheleadingcausesofprelingualHL.TreatingofhereditaryHLandunderstandingitsunderlyingmechanismsremaindifficultchallengestootolaryngologists.Asstemcellsarecapableofself-renewalanddifferentiation,theyareideallysuitedbothfordiseasemodelingandregenerativemedicine.Recently,descriptionofinducedpluripotentstemcells(iPSCs)hasallowedthefieldofdiseasemodelingandpersonalizedtherapytobecomefarmoreaccessibleandphysiologicallyrelevant,asiPSCscanbegeneratedfrompatientsofanygeneticbackground.ThisreviewbrieflydescribestheadvantagesofiPSCstechnologyanddiscussespotentialapplicationsofthispowerfulbiologicaltoolinstudyingandtreatinghereditaryHL.