1,721,004 research outputs found
Models and methods in cardiac imaging for metabolism studies
No full textCardiac health is dependent on the heart’s ability to utilize different substrates to support the overall oxidative metabolism. To characterize a variety of cardiac diseases, there is an ever growing demand for accurate noninvasive approach of myocardial substrate metabolism evaluation. Data obtained from quantitative metabolic imaging modalities add functional information to the anatomic imaging modalities and can aid patient management.
The goal of this review is to emphasize the role of noninvasive imaging techniques (such as PET, SPECT, MR spectroscopy and spectroscopic imaging) to detect the metabolic footprints of heart diseases. The advancement on models and methods to estimate kinetic parameters of dynamic processes using data acquired from cardiac imaging modalities are discussed
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
Improving sodium Magnetic Resonance in humans by design of a dedicated 23Na surface coil
No full textSodium MRI is a powerful tool for providing biochemical information on the tissue viability, cell integrity and function in quantitative and noninvasive manner and it has already been applied in vivo in most human tissues. Although it could provide useful and new information not available with classic proton MRI, the low detectable sodium signal gives rise to technological limitations in terms of data quality when using clinical scanners. The design of dedicated coils capable of providing large field of view with high Signal-to-Noise Ratio (SNR) data is of fundamental importance. This work presents magnetostatic simulation, test and application of a transmit/receive circular coil designed for 23Na MR experiments in phantoms and humans with a clinical 3T scanner. In particular, the paper provides details of the design, modeling and construction of the coil. Such coil prototype was tested at workbench by using a dual-loop probe and a network analyzer, for quality factors and Q ratios measurements. Finally, the coil was employed in MR experiments to acquire phantom and in vivo data on different human organs (heart, kidney, calf and brain). © 2014 Elsevier Ltd. 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
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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