简介：Usingofactivecardiacmedicaldevicesincreasessteadily.InEurope,therewere183implantsofICDand944implantsofPM,119ofbiventricularICDand41ofbiventricularPM,allpermillionin-habitantsin2014.Healthcareenvironments,includingradiotherapytreatmentrooms,areconsideredchallengingfortheseimplantabledevices.Exposuretoradiationmaycausethedevicetoexperienceprematureelectivereplacementindicator,decreasedpacingamplitudeorpacinginhibition,inappropri-ateshocksorinhibitionoftachyarrhythmiatherapyandlossofdevicefunction.

简介：Segmentingwholeheartfromcardiaccomputedtomography(CTimagescanprovideanimportantbasisfortheevaluationofcardiacfunctionandhelpimprovetheaccuracyofclinicaldiagnosis.Manualsegmentationisthemostaccuratemethodforcardiacsegmentation.Butitistimeconsumingandnotsufficientlyreproducible.However,cliniciansstillrelyonthismethodinpracticalapplications.Soafullyautomaticmethodisneededtoimprovethesegmentationefficiency.Thispapeproposesaregistration-basedautomaticapproachforthree-dimensional(3DsegmentationofcardiacCTimages.TheproposedmethodutilizesthesimilarityocardiacCTimagesbetweendifferentindividuals,andusesregistrationtoachievethesegmentation.Affinetransformationisfirstlyimplementedtoachieveglobalcoarseregistration.Then,cubicB-splinesareusedtorefinethelocaldetailsinlocallyaccurateregistration.Mutualinformation(Ml)isusedasthesimilaritymeasure,andadaptivestochasticgradientdescent(ASGD)astheoptimizationalgorithm.Oumethodisappliedtothedual-sourcecardiacCTimagestosegmentwholeheartExperimentalresultsshowthattheproposedmethodcanautomaticallysegmentwholeheartfromcardiacCTimages.

简介：Interfacedebondingbetweenprosthesesandabutmentswasthemostfrequentfailuremodeofresin-bondedfixedpartialsdentures(RBFPDs)inclinic.ThepurposeofthisstudywastoinvestigatetheeffectofaccessoryretentionformsonthebondstrengthofRBFPDs.Threetypesof3Dfiniteelementmodelswereconstructed.ThemodelofposteriormetalplateRBFPDwithspoon-shapedocclusalrestseatsservedasthecontrol.Theremainingtwotypesofmodelsbasedonthecontroladdedtheretentionformdesignofthepinholeandaxialgrooverespectively.Theaxialorbuccolingualloadof150Nwasappliedontheprosthesis,firstpremolarandfirstmolarrespectively.Themaximumprincipalstressesoftheadhesivelayerindifferentmodelswerecalculated.Undertheloadofthesamemagnitude,thestressduetothebuccolingualloadwassignificantlyhigherthanthatduetotheaxialloadintheadhesivelayer.Theproximalshoulder,occlusalrestseatswallandtheproximalmarginadjacenttotheshoulderwerethehighriskregionwheretheadhesivelayerdamagedeasily.Comparedwiththecontrolmodel,thepinandgroovemodelscouldslightlydecreasethestressintheadhesivelayeraftertheaxialloading,whilethestressintheadhesivelayerdrasticallydecreasedafterhorizontalloadingandreducedby22%and31%respectively.TheseresultsindicatethatthehorizontalocclusalforcehasamoreseriousharmtothedebondingofRBFPDs.Inaddition,theaccessoryretentionforms(e.g.pinandaxialgrooveretentionforms)candecreasethestresslevelintheadhesivelayer,whichareconducivetoincreasetheload-bearingcapacityofRBFPDs.

简介：目的对视觉、听觉、体感3种不同模态下靶刺激诱发的事件相关电位（ERP）进行比较研究，探讨体感电刺激作为脑机接口（BCI）一种新的信号诱发模式的可能性，为基于体感ERP的BCI研究提供理论依据。方法选择17例视力或矫正视力正常、听力正常、躯体感觉正常且无任何大脑病史的被试者，其中男性8例，女性9例；年龄20-26岁，平均年龄22．6岁：均为右利手。分别记录17例健康的被试者在视觉、听觉、体感单通道靶刺激下诱发的脑电图；对3类靶刺激下ERP的时域参数（幅值、潜伏期）、行为学数据（反应时间、错误率）、脑源定位进行比较分析。结果3类靶刺激模式下的ERP波形具有相似性，体感电刺激诱发的ERP幅值与视觉、听觉靶刺激相比无显著性差异：体感电刺激诱发ERP的峰值潜伏期显著长于视觉靶刺激：体感电刺激的反应时间显著长于视觉靶刺激。错误率也高于视觉、听觉靶刺激；体感电刺激诱发ERP的脑内源与视觉靶刺激相比具有相似性。结论相比于视觉、听觉靶刺激．大脑对于体感电刺激的探测难度高，敏感程度低：但从ERP的波形和幅值上看，体感电刺激可以诱发出稳定的、可被检测到的ERP波形，完全有可能应用于BCI系统作为一种新的ERP诱发模式。

简介：目前,经皮二尖瓣缘对缘修复术是治疗二尖瓣关闭不全的有效方式之一。超声心动图检查在该手术前可对二尖瓣病变的程度准确评估,对具体病变的部位做准确定位;在术中,可对导丝引导、钳夹装置释放等进行指导,并实时监测左心室壁运动及左心功能;在术后,可对手术近远期疗效进行评价。近年来,随着临床介入治疗的开展与提高,超声心动图在二尖瓣结构病变的介入治疗过程中发挥了一定的作用,具有重要的价值。