23 research outputs found

    Governance van innovatieve dijkconcepten in de Zuidwestelijke Delta

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    __Abstract__ Dit rapport analyseert governance factoren die het succes van het innovatief ontwikkelen van dijkzones in de Zuidwestelijke Delta bepalen. De succes- en faalfactoren zijn gebruikt om het afwegingskader Zuidwestelijke Delta aan te vullen met als uiteindelijk doel de besluitvorming over innovatieve waterkeringen als eventuele voorkeursstrategie te ondersteunen vanuit een governance perspectief. Verder beschrijft het rapport een praktische governance handreiking voor het ontwerpen, plannen en uitvoeren van innovatieve waterkeringen in de Zuidwestelijke Delta

    Determinants of Leukocyte Margination in Rectangular Microchannels

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    Microfabrication of polydimethylsiloxane (PDMS) devices has provided a new set of tools for studying fluid dynamics of blood at the scale of real microvessels. However, we are only starting to understand the power and limitations of this technology. To determine the applicability of PDMS microchannels for blood flow analysis, we studied white blood cell (WBC) margination in channels of various geometries and blood compositions. We found that WBCs prefer to marginate downstream of sudden expansions, and that red blood cell (RBC) aggregation facilitates the process. In contrast to tubes, WBC margination was restricted to the sidewalls in our low aspect ratio, pseudo-2D rectangular channels and consequently, margination efficiencies of more than 95% were achieved in a variety of channel geometries. In these pseudo-2D channels blood rheology and cell integrity were preserved over a range of flow rates, with the upper range limited by the shear in the vertical direction. We conclude that, with certain limitations, rectangular PDMS microfluidic channels are useful tools for quantitative studies of blood rheology

    Cardioprotective medication is associated with improved survival in patients with peripheral arterial disease

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    ObjectivesWe sought to investigate the effect of cardiac medication on long-term mortality in patients with peripheral arterial disease (PAD).BackgroundPeripheral arterial disease is associated with increased cardiovascular morbidity and mortality. Treatment guidelines recommend aggressive management of risk factors and lifestyle modifications. However, the potential benefit of cardiac medication in patients with PAD remains ill defined.MethodsIn this prospective observational cohort study, 2,420 consecutive patients (age, 64 Β± 11 years, 72% men) with PAD (ankle-brachial index ≀0.90) were screened for clinical risk factors and cardiac medication. Follow-up end point was death from any cause. Propensity scores for statins, beta-blockers, aspirin, angiotensin-converting enzyme (ACE) inhibitors, calcium channel blockers, diuretics, nitrates, coumarins, and digoxin were calculated. Cox regression models were used to analyze the relation between cardiac medication and long-term mortality.ResultsMedical history included diabetes mellitus in 436 patients (18%), hypercholesterolemia in 581 (24%), smoking in 837 (35%), hypertension in 1,162 (48%), coronary artery disease in 1,065 (44%), and a history of heart failure in 214 (9%). Mean ankle-brachial index was 0.58 (Β±0.18). During a median follow-up of eight years, 1,067 patients (44%) died. After adjustment for risk factors and propensity scores, statins (hazard ratio [HR] 0.46, 95% confidence interval [CI] 0.36 to 0.58), beta-blockers (HR 0.68, 95% CI 0.58 to 0.80), aspirins (HR 0.72, 95% CI 0.61 to 0.84), and ACE inhibitors (HR 0.80, 95% CI 0.69 to 0.94) were significantly associated with a reduced risk of long-term mortality.ConclusionsOn the basis of this observational longitudinal study, statins, beta-blockers, aspirins, and ACE inhibitors are associated with a reduction in long-term mortality in patients with PAD

    CM-BOF: visual similarity-based 3D shape retrieval using Clock Matching and Bag-of-Features

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    Content-based 3D object retrieval has become an active topic in many research communities. In this paper, we propose a novel visual similarity-based 3D shape retrieval method (CM-BOF) using Clock Matching and Bag-of-Features. Specifically, pose normalization is first applied to each object to generate its canonical pose, and then the normalized object is represented by a set of depth-buffer images captured on the vertices of a given geodesic sphere. Afterwards, each image is described as a word histogram obtained by the vector quantization of the image’s salient local features. Finally, an efficient multi-view shape matching scheme (i.e., Clock Matching) is employed to measure the dissimilarity between two models. When applying the CM-BOF method in non-rigid 3D shape retrieval, multidimensional scaling (MDS) should be utilized before pose normalization to calculate the canonical form for each object. This paper also investigates several critical issues for the CM-BOF method, including the influence of the number of views, codebook, training data, and distance function. Experimental results on five commonly used benchmarks demonstrate that: (1) In contrast to the traditional Bag-of-Features, the time-consuming clustering is not necessary for the codebook construction of the CM-BOF approach; (2) Our methods are superior or comparable to the state of the art in applications of both rigid and non-rigid 3D shape retrieval
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