1,720,996 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
Evaluation of a dichromatic X-ray source for dual-energy imaging in mammography
No full textA novel X-ray system, providing dichromatic beams for dual-energy radiography, has been assembled. The source generates pairs of superimposed quasi-monochromatic beams, having energies E and 2E; with E tuneable in the 15–20 keV range. In this paper the characteristics of the radiation field in terms of energy resolution and fluence, for three dichromatic X-ray beams are reported. A study of the spectra attenuated by a 5 cm-thick phantom of breast equivalent tissue demonstrates that the optimal energy of the dichromatic beam for dual-energy application may be set as a function of the thickness of investigated tissue. A detailed topographic study of mean energy and flux shows the spatial superposition of the first and the second diffraction order beam, that is the main requirement for the application of a single exposure dual-energy radiography. The bidimensional mapping of the irradiated beam is also reported, showing the presence of energy and intensity gradients. We estimate that the observed gradients do not affect the results of dual-energy technique application in an appreciable way
Quantitative analysis of the effect of energy separation in k-edge digital subtraction imaging
No full textThe aim of the work is to quantitatively compare the effect of the energy separation in the k-edge digital subtraction imaging technique. Images of a custom-made, iodine filled (k-edge = 33.17 keV) test object have been acquired with monochromatic x-ray beams (energy spread < 0.1 keV) at the ID17 biomedical beamline of the ESRF. Image acquisition has been performed using two energy separations, namely 0.65 keV (32.85 keV and 33.5 keV, respectively) and 4.4 keV (31.2 keV and 35.6 keV, respectively), using beams of energies on either side of the iodine k-edge. Signal and signal-to-noise ratio (SNR) analysis has been performed as a function of Delta E and the contrast medium concentrations. The results show that the SNR values measured for Delta E < 1 keV are only slightly higher than those measured for Delta E = 4.4 keV. This preliminary study shows that monochromaticity and the energy separation obtained with quasi monochromatic beams from conventional x-ray sources might be suitable for this imaging technique
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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