1,720,966 research outputs found
Analysis of agreement between Duplex ultrasound scanning and arteriography in patients with lower Iimb artery disease.
No full textBACKGROUND: Angiography is the gold standard for therapeutic decision-making in lower limb artery disease. However, both the potentiality and safety of Duplex ultrasound scanning suggest that it may become the main diagnostic tool. The present study aimed to investigate the agreement between Duplex scanning and angiography in the diagnosis of stenosis in lower limb artery disease.
METHODS: Forty-nine patients with lower limb artery disease (24 claudication, 12 critical ischemia, 13 skin lesions) underwent angiography and Duplex scanning. The lower limb arterial axis was divided into 15 segments and graded on the basis of the degree of stenosis (0-49%, 50-69%, 70-99% and occlusion). Agreement between angiography and Duplex scanning was assessed by Cohen's kappa statistics (kappa). The sensitivity and specificity of Duplex scanning in detecting significant stenosis at angiography (>/= 70%) were also calculated.
RESULTS: Good diagnostic agreement (kappa = 0.70; 95% CI 0.588-0.825) was achieved in the whole arterial axis. Agreement was good for the aorto-iliac district (kappa = 0.63) with a sensitivity of 63% and a specificity of 96%, and for the femoro-popliteal district (kappa = 0.70) with a sensitivity of 74% and a specificity of 83%. In infrapopliteal arteries, kappa showed a poor agreement, but Duplex scanning detected 28 patent tibial arteries in limbs that were not opacified on arteriography.
CONCLUSIONS: Duplex scanning shows good agreement with angiography in lower limb artery disease on the whole, but poor agreement in infrapopliteal districts, with a low sensitivity and high specificity in detecting significant stenoses or occlusions
Analysis of agreement between duplex ultrasound scanning and arteriography in patients with lower limb artery disease
No full textFIRST 100 CAROTID STENTING PROCEDURES IN A VASCULAR SURGERY DEPARTMENT: SELECTION CRITERIA AND RESULTS
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Fluidodynamic evaluation of arteriovenous fistulae for hemodialysis
No full textArteriovenous fistulae (AVF) are commonly used in dialysis treatment of uremic patients. However, many AVF create problems and have to be re-examined. Problems arise in the cannulation site and must be treated with antibiotics, and stenosis, both in the arterial and in the venous side of the AVF. In the worst case, the AVF must be replaced for treatment to continue. However, this can only be repeated once before the AVF site is no longer viable. This increases the discomfort, the morbidity and the mortality of the dialysis patient. Several kinds of AVF were studied to determine whether flow disturbances give rise to these complications. Many studies have already demonstrated the importance of hemodynamic factors in vascular disease pathogenesis. These factors include: the pulsatility of flow, the elasticity of the vessel, the non-Newtonian blood, flow behavior and, very importantly for AVF, the vessel geometry. In model studies, intimal changes have been observed in bends and bifurcations, regions of vessel construction and vessel stenosis. In these regions, blood flow changes abruptly and this contributes to arterial disease. We prepared several one-to-one, true-to-scale elastic silicon rubber models of different AVF. The AVF models were based on angiographic studies of chronic dialysis patients and on AVF from the arms of cadavers. The models had a similar compliance to that of the human blood vessel. Flow was visualized using photoelasticity apparatus and a birefringent blood-like fluid. This method is suitable to analyze the spatial configuration of flow profiles, to differentiate laminar flow from disturbed flow, and to visualize flow separation, vortex formation and secondary flow. It was found that AVF create disturbances that are not found under normal physiological flow conditions. The X-formed AVF was very unsatisfactory, creating significant flow disturbances. The AVF had high velocity fluctuations. These could lead, for example, to aneurysm formation. A better configuration would be an end-to-end AVF. However, this formation creates other complications. For example, there is not enough blood to the hand and parts of the hand lose feeling. The recommended AVF would be an end-to-side anastomosis. In this case, attention is needed for placement geometry, to minimize additional flow disturbances. Several models as well as patient angiographic studies are discussed
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