1,721,007 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
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
Advanced imaging in acute ischemic stroke of unknown onset
Full text linkStroke of unknown onset accounts for up to 20% of all acute ischemic stroke. Prior to the successful completion of the Efficacy and Safety of MRI-Based Thrombolysis in WAKE UP Stroke (WAKE UP) trial, these patients were typically excluded from treatment with IV tPA as this therapy was only approved for cases within 4.5 hours of known symptom onset. WAKE UP utilized a novel imaging biomarker of lesion age, the DWI-FLAIR mismatch (acute stroke visible on DWI but not yet visible on FLAIR), to allocate patients into the early time window for which thrombolysis has been proven safe and efficient; a concept which became known as “tissue clocking”. As a multicenter and imaging-heavy trial, WAKE UP relied upon a homogeneous understanding and interpretation of its imaging criteria by all of its many investigators, a process that was safeguarded by dedicated training developed especially for the study’s purposes. The study was successful and, upon its completion in 2017, together with two smaller and similar trials that were completed at comparable time points, WAKE UP generated enough high quality evidence to influence a change in official guidelines, now recommending thrombolysis for patients with stroke of unknown onset who satisfy WAKE UP criteria. Various sub-analyses conducted since on the WAKE UP cohort further cemented the credibility of tissue clocking as a patient selection paradigm. But it is not the only such model. In addition to tissue clocking another concept, dubbed penumbral imaging and used as a biomarker of tissue at risk of infarction, has also been investigated in large clinical trials such as EXTEND and ECASS-4, as a way to offer treatment to patients with unknown symptom onset. Both of these methods fall under the umbrella of advanced imaging because they necessitate hardware and/or software as well as expertise in image interpretation that is not routinely available in the majority of the world’s hospitals. Tissue clocking (using magnetic resonance imaging and the DWI-FLAIR mismatch) as well as penumbral imaging (using MR or CT based perfusion imaging) offer a lot of additional information, and through it, assurance to the treating physician that potential risks have been minimized and possible benefits of therapy enhanced. In this sense, advanced brain imaging should definitely be considered as part of state of the art, evidence based stroke treatment. Especially in the unknown time window, and due to its ability to perform both tissue clocking and penumbral imaging, MRI as a modality has been proposed as the most inclusive approach to screening ischemic stroke patients in hopes of identifying those still eligible for thrombolytic treatment. However, this approach clearly suffers the drawback of limited availability in everyday clinical practice. Further, well-designed and well-conducted prospective, randomized, controlled trials should be performed to evaluate the exact scope of (advanced) imaging needed for an as-inclusive-as-possible and successful patient selection in the unknown time window
die Suche nach genauen Prognosen von Gewebeschicksal in akutem ischämischen Schlaganfall
No full textIn perfusion magnetic resonance imaging a manual approach to delineation of
regions of interest is, due to rater bias and time intensive operator input,
clinically less favorable than an automated approach would be. We have
compared the performances of these approaches, testing the hypothesis that
automated protocols suffer from numerous artifacts which result in a false
estimation of hypoperfused tissue. An additional goal of our study was to find
a minimally biased yet maximally useful perfusion post‐processing protocol
which could offer the treating physician an estimate of tissue fate. Methods
One hundred and eighty‐four patients were included in this study, of which 39
control patients with neither a fresh infarction visible nor a final diagnosis
of stroke and 145 patients with a confirmed diagnosis of acute ischemic
stroke. Using three different software packages (Perfscape/Neuroscape, PMA and
Stroketool) maps of mean transit time (MTT), cerebral blood flow (CBF) and
Tmax were created. Three different thresholds were applied on each parameter
map and subsequent volumes of hypoperfused tissue were calculated using both a
manual and an automated protocol. Results The median difference between the
automatically and manually derived volumes was up to 210 ml in
Perfscape/Neuroscape, 123 ml in PMA and 135 ml in Stroketool. Correlation
coefficients between perfusion volumes and radiological and clinical outcome
were much lower for the automatic volumes than for the manually derived ones.
Using the manual approach in patients with a persistent vessel occlusion a CBF
map with a restrictive threshold had shown volumes of tissue at definite risk
of infarction in up to a 100% of patients. The additional use of a CBF map
with a high threshold had enabled identification of patients without penumbra.
Conclusions The agreement of the automated and manual method was very poor,
with the automated use producing falsely exaggerated volumes of hypoperfused
tissue. No one combination of software, map and threshold was able to give a
reliable estimate of tissue fate. However in patients with a vessel occlusion,
a combination of a CBF map with a low threshold and a high threshold can
provide a calculation of the minimum volume of brain tissue inevitably to be
lost if the occlusion persists.In der Perfusions-Magnetresonanztomografie ist ein manueller Ansatz zur
Abgrenzung von Schlaganfallarealen auf Grund der Bias der Begutachter und der
dafür benötigten Zeit klinisch weniger geeignet als eine automatisierter
Ansatz. Wir haben die Leistungen dieser beiden Ansätze verglichen, um zu
beweisen, dass automatisierte Protokolle zahlreichen Artefakten produzieren,
die zu einer falschen Einschätzung des hypoperfundierten Gewebes führen. Ein
weiteres Ziel unserer Studie war, eine optimierte und am wenigsten
voreingenommene Perfusionsbildgebungsverarbeitungsmethode zu finden, die dem
behandelnden Arzt eine Einschätzung über das Schicksal des Gewebes bieten
könnte. Methodik Hundertvierundachtzig Patienten wurden in die Studie
aufgenommen, davon waren 39 Kontrollen, die weder einen frischen Infarkt noch
eine endgültige Diagnose von Schlaganfall hatten und 145 Patienten mit einer
bestätigten Diagnose von akutem ischämischen Schlaganfall. Drei verschiedene
Software-Pakete (Perfscape / Neuroscape, PMA und Stroketool) wurden benutzt um
Karten von â mean transit timeâ (MTT), zerebralen Blutflusses (CBF) und
Tmax zu erstellen. Drei verschiedene Schwellenwerte wurden für jede
Parameterkarte definiert. Anschließend wurden unter der Verwendung sowohl
eines manuellen als auch eines automatischen Protokolls Volumina des
hypoperfundierten Gewebes berechnet. Ergebnisse Die mittlere Differenz
zwischen den automatisch und manuell ermittelten Volumen war bis zu 210 ml in
Perfscape / Neuroscape, 123 ml in PMA und 135 ml in Stroketool.
Korrelationskoeffizienten zwischen Perfusionsvolumina und radiologischen und
klinischen Outcome waren viel geringer für die automatische als für die
manuelle Methode. Bei Patienten mit einem persistierenden Gefäßverschluss
konnte mit den manuell erstellten CBF Karte mit einem restriktiven
Schwellenwert vom Untergang bedrohtes Risikogewebe in bis zu 100% der
Patienten identifiziert werden. Die zusätzliche Verwendung einer CBF Karte mit
einem hohen Schwellenwert ermöglichte darüber hinaus die Identifizierung von
Patienten ohne Penumbra. Zusammenfassung Die Übereinstimmung zwischen der
automatisierten und der manuellen Methode war sehr schlecht. Die
automatisierte Methode überschätzte die Volumina des hypoperfundiertes Gewebes
stark. Keine Kombination von Software, Karte und Schwellenwerten konnte eine
zuverlässige Abschätzung des Gewebeschicksals bieten. Jedoch kann bei
Patienten mit initialem Gefäßverschluss durch die Kombination einer CBF Karte
mit einem niedrigen Schwellenwert und einem hohen Schwellenwert eine
Berechnung des minimalen Volumens des gefährdeten Hirngewebes gewährleistet
werden
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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