1,720,999 research outputs found
Cerebral vasospasm in a double-injection model in rabbit.
Full text linkThe present study was designed to assess the occurrence of cerebral vasospasm following an experimental subarachnoid hemorrhage model in rabbits. Sixty-nine New Zealand albino rabbits were used in this study. One milliliter of fresh arterial blood was injected through the surgically exposed atlanto-occipital membrane over a period of 20 seconds. The procedure was then repeated 24 hours later. Fifty animals underwent digital subtraction angiography at one of the following prefixed intervals: 1, 3, or 8 days after the second injection hemorrhage. Nineteen animals underwent one angiographic examination prior to the instillation of the intracisternal blood. This procedure was followed by a repeated angiography 3 days after the second experimental subarachnoid hemorrhage. For the purpose of evaluation, the films were magnified 10-fold and the diameter of the basilar artery as well as that of the extracranial vertebral artery at three different levels were measured. We assessed the diameter of the basilar artery as well as the mean ratio extracranial vertebral artery/basilar artery diameters. This ratio was considered to minimize anatomical and technical variabilities. The results in the first 50 animals showed a trend suggesting that spasmogenic activity reaches a peak at about the third day after subarachnoid hemorrhage. These results were confirmed in the latter 19 animals. However, mortality in this group was high: 50%. This double-injection model of subarachnoid hemorrhage in rabbits consistently reproduced cerebral vascular spasm 3 days after repeated subarachnoid hemorrhage. However, its usefulness as an experimental model for subarachnoid hemorrhage is limited practically by the high animal mortality in the protocols where repeated angiographic studies are necessary
Intrasphenoidal encephalocele associated with cerebrospinal fluid fistula and subdural hematomas: technical case report.
Full text linkAbstract
OBJECTIVE AND IMPORTANCE: Intrasphenoidal encephalocele is a rare clinical entity that is often complicated by rhinorrhea, recurrent meningitis, and headache, but in no case has the association of rhinorrhea with subdural hematomas been described. A surgical procedure to stop persistent cerebrospinal fluid leakage is reported.
CLINICAL PRESENTATION: A 59-year-old man sought care for intractable rhinoliquorrhea of 6 months' duration. Cranial computed tomographic and magnetic resonance imaging scans revealed a basal posterior frontal bony defect and an evocative image suggesting intrasphenoidal encephalocele.
INTERVENTION: A transnasal transsphenoidal surgical procedure was performed; the encephalocele was removed, and the sphenoid sinus was filled with an inflatable pouch made of synthetic dura mater containing abdominal fat. Postoperative reduction of the rhinoliquorrhea, but not its total disappearance, was observed. Total disappearance was achieved only after endonasal, transmucosal inflation of the pouch with human fibrin glue. One of the subdural hematomas disappeared spontaneously, and the other was treated by a surgical procedure.
CONCLUSION: The possible role of the presented technique in the treatment of cerebrospinal fluid leakage is discusse
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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