نتایج جستجو برای: vessel diameter
تعداد نتایج: 190890 فیلتر نتایج به سال:
Despite their importance for water uptake and transport, the xylem anatomical and hydraulic properties of tree roots have only rarely been studied in the field. We measured mean vessel diameter (D), vessel density (VD), relative vessel lumen area (lumen area per xylem area) and derived potential hydraulic conductivity (Kp) in the xylem of 197 fine- to medium-diameter roots (1-10 mm) in the tops...
Bone marrow‑derived cells (BMCs) have demonstrated their ability to differentiate into multiple cell lineages and may be a promising cell source for vascular tissue engineering. Although much progress has been made in the engineering of small blood vessels (<6 mm in diameter) with biodegradable materials such as polyglycolic acid (PGA), it remains a challenge to engineer large vessels (>6 mm in...
The apparent viscosity of blood in glass tubes declines with decreasing diameter (Fåhraeus-Lindqvist effect) and exhibits a distinctive minimum at 6-7 microm. However, flow resistance in vivo in small vessels is substantially higher than predicted by in vitro viscosity data. The presence of a thick endothelial surface layer (ESL) has been proposed as the primary cause for this discrepancy. Here...
BACKGROUND To compare retinal vessel oxygenation and vessel caliber in primary angle-closure glaucoma (PACG), primary open-angle glaucoma (POAG), normal-tension glaucoma (NTG), and normal controls, as well as between eyes of asymmetrical glaucoma severity. METHODS This was a prospective, cross-sectional study. The 159 subjects (PACG, n=39; POAG, n=41; NTG, n=41; normal controls, n=38) underwe...
This thesis sought to examine the influence of the vascular bed on the tissue response to endovascular stent implantation. Closed form analytic solutions were obtained for the different beds studied. Ideal arteries were considered of normal, tapered, curved, or eccentric morphology. The application of the stent boundary conditions in the appropriate defining equations produced the desired strai...
Retinal blood flow quantification by retinal vessel segmentation with Doppler optical coherence angiography is presented. Vessel diameter, orientation, and position are determined in an en face vessel image and two representative cross-sectional flow images of the vessel. Absolute blood flow velocity is calculated with the help of the measured Doppler frequency shift and determined vessel angle...
The wood anatomy of 16 of the 37 genera within the epacrids (Styphelioideae, Ericaceae s.l.) is investigated by light and scanning electron microscopy. Several features in the secondary xylem occur consistently at the tribal level: arrangement of vessel-ray pits, distribution of axial parenchyma, ray width, and the presence and location of crystals. The primitive nature of Prionoteae and Archer...
X-ray coronary angiography is a widely used imaging technique for visualizing the presence of coronary artery disease (CAD). The measurement of arterial diameter from these images reflects disease burden, and provides an assessment of treatment benefit from existing and experimental therapies. Unfortunately, existing derivative-based and model-based measurement methods provide poor estimates fo...
Subjective estimates of the angiographic severity of coronary artery stenoses show variability and inaccuracy. We therefore tested the accuracy of a newly developed computerized image analysis system for quantitating vessel diameter from cineangiograms. Fourteen cylindrical phantoms of known diameter were filled with contrast medium and filmed over a wide range of clinically relevant radiograph...
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