简介:TP333.42000031824光盘光学系统标量衍射理论的有效性分析=Validityanalysisofscalardiffractiontheoryinopticalsystemofopticaldisk[刊,中]/成先富,贾惠波,徐端颐(清华大学精密仪器与机械学系,光盘国家工程研究中心.北京(100084))//清华大学学报.自然科学版.—1999,39(8).—53-55,59分析了标量衍射理论的能量计算误差,用耦合波理论分析了入射波偏振态的影响。计算表明TM波和TE波的衍射特性与标量理论的结论相差极大,TM波和TE波的衍射行为也有差别。图3参6(李瑞琴)
简介:DNAcondensationisanimportantprocessinmanyfieldsincludinglifesciences,polymerphysics,andappliedtechnology.Inthenucleus,DNAiscondensedintochromosomes.Inpolymerphysics,DNAistreatedasasemi-flexiblemoleculeandapolyelectrolyte.Manyagents,includingmulti-valentcations,surfactants,andneutralpoorsolvents,cancauseDNAcondensation,alsoreferredtoascoil–globuletransition.Moreover,DNAcondensationhasbeenusedforextractionandgenedeliveryinappliedtechnology.ManyphysicaltheorieshavebeenpresentedtoelucidatethemechanismunderlyingDNAcondensation,includingthecounterioncorrelationtheory,theelectrostaticzippertheory,andthehydrationforcetheory.Recentlyseveralsingle-moleculestudieshavefocusedonDNAcondensation,sheddingnewlightonoldconcepts.Inthisdocument,themulti-fieldconceptsandtheoriesrelatedtoDNAcondensationareintroducedandclarifiedaswellastheadvancesandconsiderationsofsingle-moleculeDNAcondensationexperimentsareintroduced.
简介:AdoublehelixmodelofchargetransportinDNAmoleculeisgivenandthetransmissionspectraoffourDNAsequencesareobtained.ThecalculatedresultsshowthatthetransmissioncharacteristicsofDNAarenotonlyrelatedtothelongitudinaltransportbutalsotothetransversetransportofmolecule.Theperiodicsequencewiththesamecompositionhasstrongerconductionability.Withtheincreasingofbasescomposition,theconductiveabilityreduces,buttheweightofθdirectionrisesinchargetransfer.
简介:Chaosgamerepresentation(CGR)isaniterativemappingtechniquethatprocessessequencesofunits,suchasnucleotidesinaDNAsequenceoraminoacidsinaprotein,inordertodeterminethecoordinatesoftheirpositionsinacontinuousspace.Thisdistributionofpositionshastwofeatures:oneisunique,andtheotherissourcesequencethatcanberecoveredfromthecoordinatessothatthedistancebetweenpositionsmayserveasameasureofsimilaritybetweenthecorrespondingsequences.ACGR-walkmodelisproposedbasedonCGRcoordinatesfortheDNAsequences.TheCGRcoordinatesareconvertedintoatimeseries,andalong-memoryARFIMA(p,d,q)model,whereARFIMAstandsforautoregressivefractionallyintegratedmovingaverage,isintroducedintotheDNAsequenceanalysis.ThismodelisappliedtosimulatingrealCGR-walksequencedataoftengenomicsequences.Remarkablylong-rangecorrelationsareuncoveredinthedata,andtheresultsfromthesemodelsarereasonablyfittedwiththosefromtheARFIMA(p,d,q)model.