Search results for "Vessel"
showing 10 items of 751 documents
The role of target geometry in 14 MeV neutron capture cross-section measurements
1972
Abstract Some activation capture cross sections of 14.5 MeV neutrons have been measured by systematically varying the target geometry. In all cases, the results are found to strongly depend on the geometrical conditions, which implies that a large part of the activation capture cross sections reported earlier are in error. An investigation of a number of materials shows that aluminium gives rise to a fairly small fraction of secondary low-energy neutrons and is, therefore, suitable material for target holders. A thin air-cooled target head specially designed for reliable activation cross-section measurements has been constructed and tested.
The evolution of the meaning of blood hyperviscosity in cardiovascular physiopathology: Should we reinterpret Poiseuille?
2009
In the 1960s and 1970s, a number of researchers (including ourselves) involved in the study of cardiovascular pathophysiology and particularly in the development of techniques to quantify blood flow, came across the observation that, along with vessel diameter, also blood viscosity plays an important role not only in theory but also in practice. Until then, viscosity was thought to play only a marginal role in determining blood flow, a concept which was based on the 1828 theories of Jean Louis Marie Poiseuille (Fig. 1, and [1]).1 In his well-known formula, named after its fathers Hagen2 and Poiseuille,
Autoradiographic technique to assess distribution of blood flow within organs
1969
A method is described for assessing the distribution of blood flow within organs. Microspheres, 5–50 μ in diameter, labelled with a beta-emitting isotope were injected into the left ventricle of experimental animals. The distribution of the indicator within the tissues, which is assumed to represent the regional distribution of flow, was visualized and measured quantitatively by autoradiography. Local flow rates in areas of about 1,2 mm in diameter could be determined. Application of the technique for the study of regional myocardial and renal circulation is demonstrated.
Improved technique for sheath supported contralateral limb gate cannulation in endovascular abdominal aortic aneurysm repair
2019
Summary: Background: To present a technique of sheath supported contralateral limb gate (CLG) cannulation of modular bifurcated stent-graft in endovascular abdominal aortic repair. Materials and methods: After totally percutaneous bilateral femoral access, the 9F introducer sheath is exchanged to a 30 cm 12 fr introducer sheath over a stiff wire contralateral to the intended main stent-graft insertion side and advanced into the aorta below the lowest renal artery. Parallel to the stiff wire within the sheath an additional standard J-tip guidewire with a 5 fr Pigtail angiographic catheter is advanced to the level of the renal arteries. After main body deployment, the 12 fr introducer sheath…
A Comparative Study on Feature Selection for Retinal Vessel Segmentation Using FABC
2009
This paper presents a comparative study on five feature selection heuristics applied to a retinal image database called DRIVE. Features are chosen from a feature vector (encoding local information, but as well information from structures and shapes available in the image) constructed for each pixel in the field of view (FOV) of the image. After selecting the most discriminatory features, an AdaBoost classifier is applied for training. The results of classifications are used to compare the effectiveness of the five feature selection methods.
Unsupervised recognition of retinal vascular junction points.
2014
Landmark points in retinal images can be used to create a graph representation to understand and to diagnose not only different pathologies of the eye, but also a variety of more general diseases. Aim of this paper is the description of a non-supervised methodology to distinguish between bifurcations and crossings of the retinal vessels, which can be used in differentiating between arteries and veins. A thinned representation of the binarized image, is used to identify pixels with three or more neighbors. Junction points are classified into bifurcations or crossovers according to their geometrical and topological properties. The proposed approach is successfully compared with the state-of-t…
On the Reduction of Power Consumption in Vortexing Unbaffled Bioslurry Reactors
2020
Bioremediation of polluted soils via bioslurry reactors is an interesting option among those available nowadays, especially when recalcitrant pollutants are present. Vortexing unbaffled stirred tanks may be a valuable choice to this purpose as they were recently found to be more efficient than baffled vessels for solid suspension processes where mixing time is not a controlling factor. When operated at sufficiently high agitation speeds, the central vortex bottom reaches the impeller and air bubbles start to be distributed throughout the system, thus avoiding any sparger and related clogging issues. In the present work, a vortexing unbaffled stirred tank with solid loadings ranging from 2.5…
Riflessione sulle misure di prevenzione dell'inquinamento marino dopo l'incidente della Prestige
2003
En este capítulo se analizan las medidas de prevención de la contaminación marina, en concreto, de la contaminación por hidrocarburos procedentes de buque que existían antes del accidente del superpetrolero Prestige. A continuación, se analizan las medidas adoptadas por el Estado ribereño para evitar accidentes similares en el futuro, así como las medidas propuestas por la Comisión Europea.
Size- and coating-dependent uptake of polymer-coated gold nanoparticles in primary human dermal microvascular endothelial cells.
2012
A library-orientated approach is used to gain understanding of the interactions of well-defined nanoparticles with primary human endothelial cells, which are a key component of the vasculature. Fifteen sequentially modified gold nanoparticles (AuNPs) based on three different core sizes (18, 35, 65 nm) and five polymeric coatings were prepared. The synthetic methodology ensured homogeneity across each series of particles to allow sequential investigation of the chemical features on cellular interactions. The toxicity of these nanoparticles, their uptake behavior in primary human dermal microvascular endothelial cells (HDMECs), and quantification of uptake were all investigated. The results o…
Polysorbate-80 coating enhances uptake of polybutylcyanoacrylate (PBCA)-nanoparticles by human and bovine primary brain capillary endothelial cells
2000
Certain drugs such as dalargin, loperamide or tubocurarine are not transported across the blood-brain barrier (BBB) and therefore exhibit no effects on the central nervous system. However, effects on the central nervous system can be observed when these drugs are loaded onto polybutylcyanoacrylate (PBCA)-nanoparticles and coated with polysorbate 80. The mechanism by which these complexed nanoparticles cross the BBB and exhibit their effects has not been elucidated. Cultured microvessel brain endothelial cells of human and bovine origin were used as an in vitro model for the BBB to gain further insight into the mechanism of uptake of nanoparticles. With cells from these species we were able …