Blood Flow VelocityRetinal ArteryLaser-Doppler FlowmetryRegional Blood FlowMiddle Cerebral ArteryUltrasonography, Doppler, TranscranialUltrasonography, DopplerUltrasonography, Doppler, PulsedCerebrovascular CirculationPulsatile FlowUltrasonographyCerebral ArteriesRetinal VeinBlood PressureOphthalmic ArteryRetinal VesselsUltrasonography, Doppler, ColorFlowmetersBlood CirculationHeart RateUltrasonicsChoroidHypocapniaArterial PressureReproducibility of ResultsLower Body Negative PressureDoppler EffectHemodynamicsBlood ViscosityRheologyBrachial ArteryCardiac OutputAlgorithmsReference ValuesVascular ResistanceUmbilical ArteriesTime FactorsFemoral ArteryGold RadioisotopesHyperoxiaModels, CardiovascularNadololUltrasonography, PrenatalHyperemiaSignal Processing, Computer-AssistedVeinsFetal HeartCarbon DioxideComputer SimulationDiastoleHypercapniaExerciseEchoencephalographyMicrocirculationOphthalmoscopyBlood VolumeCarotid Artery, InternalArteriesModels, StatisticalRespirationGestational AgeHemorheologyCarotid ArteriesIntraocular PressureForearmCoronary CirculationHydralazineEchocardiography, DopplerFovea CentralisDizzinessLegNeural ConductionOxygenHematocritArteriolesLikelihood FunctionsHypotension, OrthostaticPregnancyModels, BiologicalPostureSupine PositionSpectroscopy, Near-InfraredCarotid Artery, CommonBicyclingSurgical FlapsVasodilationHand StrengthOptic DiskAnalysis of VarianceMuscle, SkeletalProspective StudiesData Interpretation, StatisticalLasersStress, MechanicalRenal ArteryBiomechanical PhenomenaCarotid Artery DiseasesCold TemperatureRestJugular Veins