1,721,074 research outputs found
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
CARDIORENAL SCINTIGRAPHY WITH 99mTc-TETROFOSMIN AS AN IMAGING TOOL TO STUDY CARDIORENAL DISEASE IN ARTERIAL HYPERTENSION
No full textBackground. Renal function is a strong predictor of cardiovascular prognosis and cardiorenal disease is increasingly investigated. Cardiorenal Scintigraphy with the perfusion tracer 99mTc-Tetrofosmin was proposed as a single combined examination allowing the simultaneous investigation of heart and kidney in cardiovascular patients, including hypertensives at risk of both cardiac and renal disease (Fommei, 2009). The renal uptake index (UI) of Tetrofosmin as a percent of the injected dose was used as a renal diagnostic parameter and found to be related to clinical and scintigraphic (99mTc-DTPA) indexes of cardiorenal severity.
Aim of the study. Here we tested 99mTc-Tetrofosmin renal diagnostic validity in hypertensive patients in a comparison with 123 I-Hippuran scintigraphy as a gold standard for renal function.
Patients and Methods. 22 hypertensive patients (5 F, 17 M, age range 46-79 yrs) were scheduled for both 99mTc-Tetrofosmin cardiac G-SPECT and 123-I Hippuran scintigraphy in their diagnostic workup. As previously described, cardiorenal scintigraphy consisted in a dynamic renal acquisition after Tetrofosmin bolus injection, followed by standard cardiac G-SPECT. Hippuran scintigraphy was performed in a separate day following standard procedures. Renal images and renograms were obtained and renal uptake was calculated for each kidney both in Tetrofosmin and Hippuran scintigraphies.
Results. Tetrofosmin UI (mean 13.13±6.9 SD%) resulted lower than Hippuran UI (23.24±12.80 % (p<0.001) reflecting different intrarenal kinetics. Positive correlations were observed between the two tracers clearances and UI (either as total or separate kidney uptake) (p<.01) and between Tetrofosmin UI and age, serum creatinine, creatinine clearance and the Doppler-renal resistive index (p<.01). Five patients with angiographically confirmed renal artery stenosis showed corresponding renographic and scintigraphic abnormalities with both tracers.
Conclusions. 99mTc-Tetrofosmin cardiorenal scintigraphy may be used to obtain simultaneous renal and cardiac functional information which may be relevant for diagnosis and prognosis in states of cardiorenal diseases, with no study lenghtening nor an increase in the radiation burden to the patient compared to a standard cardiac study
Assessment of myocardial adrenergic innervation with a solid-state dedicated cardiac cadmium-zinc-telluride camera: First clinical experience
No full textAimsTo investigate the relationships between regional adrenergic innervation heterogeneity, myocardial perfusion, and contractile function obtained by means of a low-dose imaging protocol with a cadmium-zinc-telluride (CZT) dedicated camera.MethodsTwenty-eight patients with or without ischaemic heart disease underwent 123I-metaiodobenzylguanidine (MIBG) planar scintigraphic and CZT early and delayed evaluations followed by 99mTc-tetrofosmin rest gated CZT with a single-day protocol. The heart-to-mediastinum ratio and the washout rate were computed from planar 123I-MIBG images. The summed 123I-MIBG defect scores (SS-MIBG) were semi-quantitatively assessed from CZT images. The summed rest score (SRS), summed motion score (SMS), and summed thickening score (STS) were quantitated from 99mTc-tetrofosmin images.ResultsSixteen patients showed a depressed left ventricular systolic function [ejection fraction (EF)<50%]. They presented higher SRS (P = 0.007), SMS (P < 0.001), STS (P < 0.001), and early SS-MIBG (P = 0.007) values than those with normal contractile function. Interestingly, higher early SS-MIBG values, index of regional sympathetic innervation heterogeneity, clustered with more elevated SRS (P = 0.023), and more impaired measures of regional and global left ventricle systolic function, i.e. SMS (P = 0.046), STS (P = 0.014), and EF (P = 0.027). At multivariate analysis, a higher SRS (P = 0.039) remained the only independent predictor of more elevated early SS-MIBG values. In the 20 of 28 ischaemic patients, the correlations between early SS-MIBG and SMS (P = 0.017) and also STS (P = 0.036) were further confirmed. The effective dose of the investigation was 4.2 ± 0.72 mSv.ConclusionsAn altered early SS-MIBG, assessed with a low-dose imaging protocol and a CZT cardiac camera, identifies patients with more impaired myocardial perfusion and contractile function. © 2014 Published on behalf of the European Society of Cardiology. All rights reserved
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
PET-CT evaluation of amyloid systemic involvement with [18F]-florbetaben in patient with proved cardiac amyloidosis: a case report
No full textBackground: One of the most frequent disorders which lead to cardiac amyloidosis is transthyretin-related amyloidosis (ATTR). Some PET radio-pharmaceuticals for the detection of beta-amyloid deposits within the brain have shown to be able to detect also cardiac amyloid deposits. We present a case of a man with ATTR studied with [18F]-florbetaben PET-CT. Results: Total-body scan showed a moderate uptake in the bone marrow, especially in correspondence of the vertebral column, while no significant myocardial uptake was present. Cardiac-focused scans showed low mean cardiac SUV values confirming the absence of significant myocardial uptake. Brain scan showed a significant cortical brain uptake of the radio-pharmaceutical more evident in correspondence of frontal and temporal lobes. Conclusions: Distinct subtypes of amyloidosis show different uptake of the radiotracer. Brain amyloid deposition in the presence of a systemic disease could not be caused by the same amyloid precursor
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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