1,720,959 research outputs found
Fusion imaging technology of the intracranial veins
No full textOBJECTIVES: Fusion imaging technology (FIT) combines different imaging techniques by means of properly designed software. The aim of this study was to validate the ultrasonographic representation of intracranial vein anatomy by combining transcranial echo-colour Doppler (TECD) with conventional magnetic resonance imaging (MRI). In addition, we investigated the possibility of insonating the veins of the base of the skull through the novel condylar window. METHODS: We examined venous brain circulation in five healthy subjects by means of FIT, using a 1.5 T MR scanner and an ultrasound TECD equipped with Virtual Navigator technology.Results and conclusionsInsonation of the Rosenthal and other intracranial veins through the classical transtemporal window, based on anatomical assumption, but never before validated by means of FIT study, was confirmed. Moreover, in all five subjects, FIT demonstrated the possibility of insonating the petrosal sinuses and the cavernous sinus area through the novel transcondylar approach. In conclusion, the feasibility of FIT of the intracranial veins potentially permits to study subjects in different postures and/or at the bed of non-transportable patients, after the initial MRI acquisition. Finally, the novel transcondylar approach allows obtaining haemodynamic information from the cavernous and the petrosal sinuses usually not investigated by TECD alone
Screening for chronic cerebrospinal venous insufficiency (CCSVI) using ultrasound: recommendations for a protocol.
No full textChronic cerebrospinal venous insufficiency (CCSVI) is a syndrome characterized by stenoses or obstructions of the internal jugular and/or azygos veins with disturbed flow and formation of collateral venous channels. Ultrasound and venographic studies of the internal jugular and azygos venous systems in patients with multiple sclerosis (MS) have demonstrated a high prevalence of CCSVI (mean 71%, range 0-100%; n=1336) associated with activation of collaterals. By contrast, ultrasound and venographic examinations of normal controls and patients without MS have demonstrated a much lower prevalence (mean 7.1%, range 0-22%; n=505). Ultrasound in the form of duplex scanning uses a combination of physiological measurements as well as anatomical imaging and has been used for the detection of CCSVI by different centers with variable results. A high prevalence of obstructive lesions, ranging from 62% to 100%, has been found by some teams in patients with MS compared with a low prevalence (0-25%) in controls. However, others have reported absence of these lesions or a lower prevalence (16-52%). This variability could be the result of differences in technique, training, experience or criteria used. In order to ensure a high reproducibility of duplex scanning with comparable accuracy between centers a detailed protocol with standard methodology and criteria is needed. Also, standardization of the method of reporting of duplex measurements and other findings will facilitate validation of the proposed criteria by different centers. The aim of this document is to produce recommendations for such a protocol and indicate what future research is needed in order to address areas of uncertainty
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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