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简介：Thispaperpresentsthedevelopmentofthebloodflowsimulationintwodimensionsovertherealgeometryofthefemoralartery.TheNavier-Stokesequationsaresolvedusingthefiniteelementmethod,toobtainthedistributionsofthebloodpressureandflowvelocityinmultipleinstantsoftimeanddifferentplacesofthefemoralarteryandthusdeterminethecurrentconditionofthebloodvessels.Thevelocityfieldshowsalaminarbehavior,where,thevelocityishigherinthecenterofthearteryanddecreasesasthebloodflowapproachesarterywalls.Inspiteofallarteryandbloodflowpropertiesnotbeingconsidered,thevaluesofpressureandvelocityobtainedarewithinthenormalranges.Finallythemodelisusedtoverifyifthereexistirregularitiesinthebloodflowinbothhealthysubjectsandsickpatients.

简介：AbstractObjective:This article aimed to compare the peripheral blood flow intensity (BFI) in the maternal right and left kidney in uncomplicated third trimester pregnancies and to study possible associations between parenchymal BFI in the kidneys and maternal, labor and new-born characteristics.Methods:We conducted a prospective cohort study in third trimester pregnancies at Trondheim University Hospital, Norway, from January to April 2018. The BFI in the maternal kidneys was examined with color Doppler ultrasound and the peripheral BFI was calculated using the Pixel Flux-method which is a method based on pixel wise calculation of color in an image. Velocity was coded by the color bar in the ultrasound device. The peripheral BFI was calculated as the product of velocity and area encoded by all colored pixels divided by all pixels within the cortical layer by a software examining the color in each pixel of a standardized region of interest of the renal parenchyma in video-clips through a complete heart cycle. BFI (cm/s) was thus calculated as follows:The primary outcome measure was peripheral BFI in the renal cortex. We also examined associations between BFI in the entire cortex with maternal age, body mass index, blood pressure, pH in the umbilical artery, Apgar score after 5 minutes and birthweight.Results:In all, 51 pregnant women were included in the study, but 17 were excluded, mainly due to movement artifacts from the pulsating aorta, leaving 34 women in the final study population. We found significantly lower BFI in the cortex of the left kidney compared with the right kidney, 0.37 cm/s versus 0.69 cm/s, respectively (P = 0.04). Dividing into regions, the BFI was significantly lower in the proximal 25% of the left renal cortex compared to the corresponding right side (P= 0.01), and in the proximal 50% cortex (P= 0.02), but the differences were not significantly different in the distal 25% (P= 0.06) or in the distal 50% (P= 0.20) of the renal cortex.We observed a significant negative correlation between peripheral BFI in the left kidney and both systolic blood pressure (r = -0.38; P= 0.03) and diastolic blood pressure (r= -0.36; P= 0.04), and no significant correlations between BFI with maternal age, body mass index, blood pressure, pH in the umbilical artery, Apgar score after 5 minutes and birthweight in the left kidney (P > 0.05). We did not observe any significant correlations between BFI in the right kidney and maternal or new-born characteristics (P > 0.05).Conclusion:The BFI in the left renal cortex was lower compared with the right renal cortex, and BFI in the left renal cortex was negatively correlated with blood pressure, but not significantly correlated with maternal age, body mass index or newborn characteristics. We did not observe any significant correlations between BFI in the right kidney and maternal or new-born characteristics.

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简介：Basedonestablishednumericalmethodsandhydrodynamicperformancetestingfacilities,CFDtechniqueareappliedtoimprovethedesignoftheimplantableaxialflowbloodpumpandtheflowanalysis.(1)Applyingbrushlessmachinemagnetsteel,reducingitsthicknesswhileincreasingthelength,theflowchannel'scross-sectionisincreased,withnospaceconnectionbetweenthelargeandthesmallrotators,andwithaconetransitionsegmentfromthebearingtotheprincipalaxis,theflowismadesmoother.Therotatingspeedisloweredby1000rpm-1200rpmunderthesameflowrateandpressurehead,andthusthehemolysiscanbeavoided.(2)Differentoutletstatorguidingvanesareselectedforthesamebloodpumpforanalysesofhydrodynamicperformancesandflowfields.Anexcellentdesignnotonlycanregulatetherotatingflowfieldintoanaxialone,reducethecirculationlossandimprovethepumpefficiency,butalsocanavoidbackflow,vortexandsecondaryflowatthepumpoutlet,andthusthethrombuscanbeprevented.(3)Thecalflivetestsshowthatsomeresidualclotsexistattheinnerwalloftheoutletconnectionbends,whichareanalyzedandexplainedbyCFDtechniquesandthecorrespondingimprovementsareproposed.AllresultsareverifiedbyhydrodynamicperformancetestsandPIVflowfieldtests,andconsistentconclusionsareobtained.

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简介：纸由使用biomagnetic液体动力学(BFD)的原则通过一个多孔的中等题目处理biomagnetic液体流动的一个基本问题的理论调查到一个磁场。学习与液体的磁化与温度变化的一种状况相关。液体被认为非牛顿，其流动被一个二年级的方程管理粘弹性的液体。隧道的墙被假定可拉长，在表面速度与从坐标的起源的纵的距离成正比的地方。这个问题首先被归结为解决包含七个参数的联合非线性的微分方程的一个系统。把血看作biomagnetic液体并且使用现在的分析，被尝试由开发一个合适的数字方法并且由设计一个适当有限差别计划计算血流动的一些参数。计算结果在图形的形式被介绍，并且从而，一些理论预言在一个磁场的行动下面处于一个过高热的状态关于血的hemodynamical流动被做。结果清楚地显示磁性的偶极子的存在忍受潜力以便在电磁的过高热的治疗学的过程期间在动脉影响血流动的特征到重要程度。学习将吸引临床医生，结果将在由电磁的过高热的方法的癌症病人的治疗是谁有用的注意。

简介：Thehemodynamicmechanismofrollingmanipulation(RM)oftraditionalChinesemedicalmassage(TCMM)isinvestigated.AnaxisymmetricalnonlinearmodelandanarbitraryLagrangian-Eulerianfiniteelementmethod(ALE-FEM)withrezoningalgorithmwereintroducedtostudytheviscousflowthroughanaxisymmetricalrigidtubewithaxiallymovingstenosistosimulatetherollingmanipulation.FlowrateandwallshearstresswereobtainedbysolvingcompleteNavier-Stokesequationsnumerically.Thenumericalresultsshowthatthestenosismovingfrequency,namelythefrequencyofrollingmanipulation,hasgreateffectonthedisturbanceofflowandthewallshearstress.Thestenosiscoefficient,whichcharacterizestheseverityofthestenosis,anotheradjustableparameterinrollingmanipulation,alsoshowsthesignificanteffectonflowrateandwallshearstress.Thesenumericalresultsmayprovidesomedatathatcanbetakenintoconsiderationwhenmassageisusedinclinic.

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简介：Anumericalanalysisofnon-Newtonianfluidflowinnon-planararterywithbifurcationwasperformedbyusingafiniteelementmethodtosolvethethree-dimensionalNavier-Stokesequationscoupledwiththenon-Newtonianconstitutivemodels,includingCarreau,CrossandBinghammodels.Theobjectiveofthisstudyistoinvestigatetheeffectsofthenon-Newtonianpropertiesofbloodaswellascurvatureandout-of-planegeometryinthenon-planardaughtervesselsonthevelocitydistributionandwallshearstress.Theresultsofthisstudysupporttheviewthatthenon-planarityofbloodvesselsandthenon-Newtonianpropertiesofbloodareofimportantinhemodynamicsandplayasignificantroleinvascularbiologyandpathophysiology.

简介：Background:Apreviousstudyhasreporteda50%reductionindisuseatrophyofthequadricepsduringthefirst14daysafteranteriorcruciateligament(ACL)reconstruction.Afollow-uptrialisneededtoconfirmthesepromisingresults.ThepresentstudyaimstoinvestigatetheeffectofanocclusionstimulusonquadricepsatrophyafterACLreconstruction.Methods:Atotalof24subjectsparticipatedinthestudy.Theywererandomizedintotwogroups.Startingthe2nddayaftersurgery,theocclusiongroupreceivedanocclusionstimulusfor5min,followedbyremovaloftheocclusivepressurefor3min.Thiswasrepeatedfivetimesinonetrainingsession,twicedaily.Duringtheperiodofocclusivestimulus,thesubjectsperformed20lowloadexercisesforthequadriceps.Thecontrolgroupfollowedthesameexerciseprotocol,butwithouttheocclusionstimulus.Changesinquadricepsanatomicalcrosssectionarea(ACSA)weremeasuredusingaxialmagneticresonance(MR)imagesat40%and50%ofthelengthofthefemur.Results:BothgroupshadasignificantreductionofquadricepsACSAfrom2daysbeforesurgeryto16daysaftersurgery.Duringtheinterventionperiod,theocclusiongrouplost13.8%±1.1%(mean±SEM)andthecontrolgrouplost13.1%±1.0%oftheirquadricepsACSA,respectively.Therewasnosignificantdifferencebetweentheocclusionandcontrolgroupswithregardstoatrophyofthequadricepsmuscles.Conclusion:Inconflictwithotherstudiesusingasimilarprotocol,applicationofbloodflowrestrictionthefirst14daysafterACLreconstructiondidnotreducequadricepsACSAmuscleatrophymeasuredbyMRinapopulationofathletes.

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简介：ObjectivesNitroglycerine(NTG)enhancescoronarybloodflowtocompromisedmyocardiumisimportantinrelievingischemia.However,themechanismforthisincreaseinmyocardialbloodflow(MBF)isnotwelldefined.Insmallvesselsandcapillaries,relativebloodviscosityplaysaveryimportantroleindeterminingmyocardialvascularresistance(MVR).MVRreduceisduepartlytotheincreaseinnegativechargeoferythrocytesurface.WethereforehypothesizedthattheenhancementofnutrientbloodflowtozonesofmyocardialischemiaduringNTGispartlysecondarytoreducedMVRandbloodflowviscosity.Thelatterisaffectedbythenegativechargeoferythrocytesurface.Methods6dogswithLADflow-limitingstenosis(group1)and6dogswithLADflow-limitingstenosisandLCxoccmusion(group2)werestudied.AtbaselineandduringintracoronaryinfusionsofNTG(0.3-0.6μg·kg-1·min-1),hemodynamics,MBF(mL·min-1·g-1),wholebloodviscosity(WBη,mPa.S),elongationindex(EI),eletrophoreticmobilityoferythocytes(EME,[μ.s-1)/(V.cm-1)])andpercentwallthickening(%WT)weredetermined.MVRwascalculatedusingdrivingpressure/MBF.ResultsAscomparedtobaseline,nochangesinhemodynamicswereseenduringNTG.MBFincreasedandMVRdecreasedsignificantlyinnormalbed,thecentral25%andtheentireofstenosedbed(P<0.05),withadecreaseinWBηinbothgroup1andgroup2dogs(18.6±9.7%and19.2±14.5%,respectively).However,the%decreaseinWBηwasproportionedtothe%increaseinMBForthe%decreaseinMVRonlyinthecentral25%ofstenosedbed(r=0.87,P<0.001),butnotintheentirestenosedbedandnormalbed.EIdidnotshowstatisticallysignificantdifferencesbetweenduringNTGandatbaseline,butEMEdidincrease.Andthe%decreaseinWBηduringNTGwasrelatedtothe%increaseinEME(r=0.83,P=0.01).ConclusionsNTGreducedmyocardialvascularresistanceandbloodviscosityduetothechangeofnegativechargeoferythrocytesurfacemay,inpart,bethe

简介：Thepaperstudiestheproblemoffluidflowandfluidshearstressincanaliculiwhentheosteonissubjecttoexternalmechanicalloadingandbloodpressureoscillation.Thesingleosteonismodeledasasaturatedporoelasticcylinder.Solidskeletonisregardedasaporoelastictransverselyisotropicmaterial.Togetnear-realisticresults,boththeinterstitialfluidandthesolidmatrixareregardedascompressible.BloodpressureoscillationintheHaveriancanalisconsidered.Usingtheporoelasticitytheory,ananalyticalsolutionoftheporefluidpressureisobtained.Assumingthefluidincanaliculiisincompressible,analyticalsolutionsoffluidflowvelocityandfluidshearstresswiththeNavier-Stokesequationsofincompressiblefluidareobtained.Theeffectofvariousparametersonthefluidflowvelocityandfluidshearstressisstudied.更多还原

简介：FromApril1995toOctober1999,135patientswithconcussionofbrainwereexaminedwiththreedimensionaltranscranialDoppler(3D-TCD)andthechangeofcerebralbloodflowinvariousphaseswasanalyzedtoevaluatetheeffectof3D-TCDondiagnosisandtherapyofbrainconcussion.

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