1,720,968 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
Noninvasive Assessment of Cerebral Perfusion and Oxygenation in Acute Ischemic Stroke by Near-Infrared Spectroscopy
No full textBackground: In acute stroke patients, there is a need for noninvasive measurement to monitor blood flow-based therapies. We investigated the utility of near-infrared spectroscopy (NIRS) to determine cerebral perfusion in these patients. Methods: Eleven patients were investigated within 1.4 +/- 2.2 days after onset of an ischemic middle cerebral artery infarction by monitoring the kinetics of an intravenous bolus of indocyanine green (ICG). For ICG kinetics, bolus peak time, time to peak (TTP = time between 0 and 100% ICG maximum), maximum ICG concentration, rise time (time between 10 and 90% ICG maximum), slope (maximum ICG/TTP), and blood flow index (BFI = maximum ICG/rise time) were obtained. Perfusion-weighted MRI (PWI) and NIRS measurements were performed within 24 h, and the interhemispherical differences of TTP values were compared. Results: Stroke patients showed an increased bolus peak time (p < 0.02), TTP (p < 0.01), and rise time (p < 0.01), whereas slope (p < 0.01) and BFI ( p ! 0.01) were diminished at the site of infarction as compared to the unaffected hemisphere. The interhemispherical differences of TTP as measured by PWI and NIRS were closely correlated (r = 0.86). Conclusions: Noninvasive measurements of cerebral ICG kinetics by NIRS provide a useful means of detecting cerebral perfusion deficits in patients with acute stroke, which correlate well with those obtained by PWI. Copyright (C) 2009 S. Karger AG, Base
Early disruption of the blood-brain barrier after thrombolytic therapy predicts hemorrhage in patients with acute stroke
No full textBackground and Purpose-Leaks of the blood-brain barrier can be detected on postcontrast-enhanced T1-weighted MRIs. Although early disruptions of the blood-brain barrier appear to be an important risk factor for tissue plasminogen activator-related hemorrhages in rodents, little is known about their incidence and consequences in human stroke. Methods-This is a retrospective analysis of a prospectively collected stroke database over the past 6 years. In 52 patients, multimodal MRI (including diffusion-weighted, perfusion-weighted, and postcontrast-enhanced T1-weighted MRI to detect blood-brain barrier changes) had been performed immediately before systemic thrombolysis and in 48 patients within a median of 30 minutes (interquartile range: 30 to 60 minutes) after recombinant tissue plasminogen activator treatment. The incidence of symptomatic hemorrhage (SICH), defined as any parenchymal hemorrhage leading to deterioration in the patient's clinical condition, was related to several clinical and imaging variables, including early blood-brain barrier changes. Results-Overall, SICH was detected in 9 (9%) patients and among these, 2 died. Although no blood-brain barrier changes were detectable before thrombolysis, 3 of 48 patients (6.25%) had a parenchymal gadolinium enhancement in the areas of initial infarction after tissue plasminogen activator treatment. All 3 patients developed SICHs at sites corresponding to the areas of enhancement. The presence of a parenchymal enhancement was significantly associated with SICH (P < 0.01), whereas other clinical and imaging variables did not predict SICH in this series. Conclusion-Early parenchymal enhancement after intravenous tissue plasminogen activator is significantly associated with subsequent SICH and could therefore become a useful imaging sign for the rapid initiation of preventive strategies in the future
Effects of physiological aging and cerebrovascular risk factors on the hemodynamic response to brain activation: a functional transcranial Doppler study
No full textThe influence of the vascular system on the coupling of cerebral blood flow (CBF) to focal brain activation during aging is incompletely understood. Using functional transcranial Doppler sonography and a hypercapnic challenge as a marker of intact cerebral vasoreactivity, we determined CBF velocity (CBFV) changes in response to a language and arithmetic task in a group of 43 healthy young subjects (mean age 32 +/- 8.6 years), 18 healthy old subjects (mean age 64 +/- 9.8 years) and 29 old subjects with risk factors for an atherosclerosis (mean age 69 +/- 8.4 years). Despite a similar performance during the cognitive tasks the CBFV changes were significantly lower in the group of old subjects with vascular risk factors compared with the healthy young and old subjects. Similarly, the CBFV changes during hypercapnia were significantly lower in the group of old subjects with vascular risk factors compared with the healthy young and old subjects. In contrast, both cognitive tasks and hypercapnia produced comparable CBFV changes in the group of healthy young and old subjects. These results suggest that the hemodynamic response to neuronal activation is unaffected by aging alone, whereas the presence of cardiovascular risk factors significantly diminishes the capability of cerebral vessels to react to vasodilating stimuli
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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