简介:LFA-1andMac-1,twoβ2integrinmembersconstitutivelyexpressedonneutrophils,mediateleukocyterecruitmentcascadebybindingtothesameligandofICAM-1.TheslowrollingandfirmadhesionofleukocytesrelyonLFA-1whilethecellcrawlingisdependentonMac-1.Wehypothesizedthattheirdistinctroleswerelikelyattributedtothedifferencesinthebindingkineticsorinthediverseresponsesofoutside-inandinside-outsignaling.Inthisstudy,wecomparedtheICAM-1bindingfeaturesbetweensolubleormembrane-expressedLFA-1andMac-1withdifferentaffinityconformationsusingopticaltraptechnique.Ourdataindicatethattheaffinityup-regulationfromwidetype(WT)tohighaffinity(HA)isoff-ratedependentforLFA-1buton-ratedependentforMac-1.Thestructuralbasesofthisnewfindingwerefoundtobeconsistentwithourprevioussimulations.Theseresultsfurtheredourunderstandingontheirfunctiondifferencesundershearflow.
简介:摘要:随着现在车辆的普及,导航软件已经成为出租车司机以及私家车车主出行所必备的工具之一,它能让车主实时的获得GPS数据,以确定当前道路的情况,但在道路拥挤的路段,导航软件对行车速度估计非常不准确,进而造成对道路拥堵时间的估计精度较低,因此如何提高对拥堵时间的估计精度是当前面临的问题之一。
简介:Tostudytheelectromagnetic(EM)backscattercharacteristicsoffreakwavesatmoderateincidenceangles,weestablishanEMbackscatteringmodelforfreakwavesin(1+1)-dimensionaldeepwater.ThenonlinearinteractionbetweenfreakwavesandBraggshortwavesisconsideredtobethebasichydrodynamicspectramodulationmechanisminthemodel.NumericalresultssuggestthattheEMbackscatteringintensitiesoffreakwavesarelessthanthosefromthebackgroundseasurfaceatmoderateincidenceangles.Thenormalisedradarcrosssections(NRCSs)fromfreakwavesarehighlypolarisationdependent,evenatlowincidenceangles,whichisdifferentfromthesituationfornormalseawaves;moreover,theNRCSoffreakwavesismorepolarisationdependentthanthebackgroundseasurface.NRCSdiscrepanciesbetweenfreakwavesandthebackgroundseasurfacewithusinghorizontaltransmittinghorizomtal(HH)polarisationarelargerthanthoseusingverticaltransmittingvertical(VV)polarisation,atmoderateincidentangles.NRCSdiscrepanciesbetweenfreakwavesandbackgroundseasurfacedecreaseswiththeincreaseofincidenceangle,inbothHHandVVpolarisationradars.Asanapplication,inthesynthetic-apertureradar(SAR)imagingoffreakwaves,wesuggestthatfreakwavesshouldhaveextremelylowbackscatterNRCSsforthefreakwavefacetwiththestrongestslope.Comparedwiththebackgroundseasurface,thefreakwavesshouldbedarkerinHHpolarisationechoimagesthaninVVechoimages,inSARimages.FreakwavescanbemoreeasilydetectedfromthebackgroundseasurfaceinHHpolarisationimagesthaninVVpolarisationimages.Thepossibilityofdetectionoffreakwavesatlowincidenceanglesismuchhigherthanathighincidenceangles.