How good are the fits to the experimental velocity profiles in vivo?

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.A new velocity profile equation for the description of microcirculatory blood flow in vivo was proposed in 2009. However various recently published papers still use the assumption of parabolic velocity profile (Poiseuille flow). The purpose of this work was to evaluate the performance of 3 different fitting cases: 1) best parabolic fit, 2) axial fit with the proposed equation and 3) best fit with the proposed equation. Twelve experimental velocity profiles measured by particle image velocimetry in mouse venules were used to compare the fitting efficiency of the 3 cases on the basis of the velocity relative error (RE) expressed as average ± SE (standard error) at ten different radial segments (REj with 1 ≤ j ≤ 10). The parabolic best fit (case 1) leads to serious deviations from the real velocity distribution (RE10 = - 65% ± 2%). The proposed equation axial fit (case 2) slightly overestimates blood velocity distribution near the vessel wall but the was below + 12% and it requires only one experimental value near the vessel axis, measurable using the Doppler Effect. The proposed equation best fit (case 3) approximates the experimental data without any serious bias but requires a complete velocity profile data set

KLJUČNI DOGAĐAJI U POVIJESTI DJEČJE KIRURGIJE ZA VRIJEME BIZANTA

During the Byzantine Times, medicine and surgery developed as Greek physicians continued to practice in Constantinople. Healing methods were common for both adults and children, and pediatrics as a medical specialty did not exist. Already Byzantine hospitals became institutions to dispense medical services, rather than shelters for the homeless, which included doctors and nurses for those who suffered from the disease. A major improvement in the status of hospitals as medical centers took place in this period, and physicians were called archiatroi. Several sources prove that archiatroi were still functioning in the late sixth century and long afterward, but now as xenon doctors. Patients were averse to surgery due to the incidence of complications. The hagiographical literature repeated allusions to doctors. Concerns about children with a surgical disease often led parents to seek miraculous healings achieved by Christian Protectors – Saints. This paper is focused on three eminent Byzantine physicians and surgeons, Oribasius, Aetius of Amida, Paul of Aegina, who dealt with pediatric operations and influenced the European Medicine for centuries to come. We studied historical and theological sources in order to present a comprehensive picture of the curative techniques used for pediatric surgical diseases during the Byzantine Times.U bizantsko doba medicina i kirurgija razvijali su se dok su grčki liječnici nastavili s praksom u Carigradu. Metode liječenja i za odrasle i za djecu se nisu razlikovale, a pedijatrija kao medicinska specijalizacija nije postojala. Bizantske bolnice postale su ustanove, a ne skloništa za beskućnike, u kojima su liječnici i medicinske sestre pružali medicinske usluge za sve oboljele. U ovom se razdoblju dogodilo veliko poboljšanje statusa bolnica kao medicinskih centara, a liječnici su prozvani archiatroi. Nekoliko izvora dokazuje da su archiatroi još uvijek djelovali u kasnom šestom stoljeću i dugo nakon toga, ali sada kao ksenonski liječnici. Pacijenti nisu bili skloni operacijama zbog učestalosti komplikacija. U hagiografskoj literaturi su se učestalo spominjali liječnici. Zabrinutost za djecu s kirurškom bolešću roditelje je često tjerala da traže čudesna ozdravljenja koja su prakticirali kršćanski sveci zaštitnici. Ovaj rad govori o tri ugledna bizantska liječnika i kirurga. Oribazije, Aecije iz Amide i Pavao iz Aegine bavili su se pedijatrijskim operacijama i utjecali na europsku medicinu u idućim stoljećima. Proučavali smo povijesne i teološke izvore kako bismo predstavili sveobuhvatnu sliku kurativnih tehnika koje su korištene za dječje kirurške bolesti u bizantsko doba

Loss of field of view due to optical mismatch at the inner diametric plane of cylindrical artificial microvessels

In the experimental research with cylindrical artificial microvessels it may not be possible to view the entire inner diameter, due to optical mismatch between the microvessel material and the inside liquid suspension. A quantification of the field of view loss (FOVL) at the inner diametric plane is proposed, when the liquid suspension has a lower refractive index than the microvessel material and imaging is performed by a dry objective lens. A graphical model shows the optical ray tracing, utilizing 3 different refractive indices (η1, η2 and η3) for the microvessel material, the liquid suspension and the air. The numerical aperture (NA) of the objective lens defines the maximum ray output angle received by the lens and corresponds to a certain FOVL. Output angles were estimated for 8 different input angles and the corresponding FOVLs ranged from 71% down to 2%. The graphical model theoretical estimations were assessed experimentally for the cases of a water suspension and a plasma diluted blood sample (5% hematocrit). The theoretical estimations deviated only ±3% from the experimental assessments, showing that the graphical model could be a valuable tool for research on cylindrical artificial microvessels with dry objective lenses. © 202

Vessel Sampling and Blood Flow Velocity Distribution With Vessel Diameter for Characterizing the Human Bulbar Conjunctival Microvasculature

PURPOSE: This study determined (1) how many vessels (i.e. the vessel sampling) are needed to reliably characterize the bulbar conjunctival microvasculature and (2) if characteristic information can be obtained from the distribution histogram of the blood flow velocity and vessel diameter. METHODS: Functional Slit-lamp Biomicroscope was used to image hundreds of venules per subject. The bulbar conjunctiva in 5 healthy human subjects was imaged on 6 different locations in the temporal bulbar conjunctiva. The histograms of the diameter and velocity were plotted to examine whether the distribution was normal. Standard errors were calculated from the standard deviation and vessel sample size. The ratio of the standard error of the mean over the population mean was used to determine the sample size cutoff. The velocity was plotted as a function of the vessel diameter to display the distribution of the diameter and velocity. RESULTS: The results showed that the sampling size was approximately 15 vessels, which generated a standard error equivalent to 15% of the population mean from the total vessel population. The distributions of the diameter and velocity were unimodal, but also somewhat positively skewed and not normal. The blood flow velocity was related to the vessel diameter (r =0.23, P < 0.05). CONCLUSION: This was the first study to determine the sampling size of the vessels and the distribution histogram of the blood flow velocity and vessel diameter, which may lead to a better understanding of the human microvascular system of the bulbar conjunctiva

Meta-analysis of conjunctival microvascular hemorheology metrics

[No abstract available