1,720,990 research outputs found
Beta amyloid deposition in infarct and peri-infarct areas assessed using 11C Pittsburg Compound B and positron emission tomography
No full text© 2012 Dr. Ramesh SahathevanIntroduction: Alzheimer’s disease (AD) and vascular cognitive impairment (VCI) are the most common forms of dementia. There is epidemiological evidence that vascular risk factors are associated with an increased risk of developing both AD and VCI. The risk conferred by these vascular factors is independent of their risk of increasing stroke. Approximately 30% of stroke survivors develop dementia and as many as 50% of them may have mixed pathology of AD and VCI. The histopathological confirmation of the AD/VCI overlap suggests that the two conditions may form opposing ends of a spectrum of disease. It also supports the theory that acute and/or chronic ischaemia factor in the pathogenesis of AD. The pathological hallmark of AD is cerebral amyloid (Aβ) deposited mainly as extracellular neuritic plaque or in the wall of leptomeningeal vessels. Advances in positron emission tomography (PET) now allow for in vivo imaging of Aβ. The aim of this study is to determine the immediate and long-term effects of an acute stroke on Aβ deposition. It also aims to assess the influence of vascular disease on Aβ.
Methods: Eligible patients admitted with ischaemic stroke underwent an MRI or CT brain to determine stroke characteristics and 11C-PiB-PET scan to enable semi-quantitative estimation of Aβ. Forty-eight stroke patients were included in the analyses and compared against an equal number of controls. Repeat PET scans were performed at intervals ranging from 2 weeks to 18 months. The PET scans were analysed using standard uptake value ratios (SUVR) calculated for the whole brain, the cerebral hemisphere affected by stroke and stroke specific regions. The values were compared to similar SUVR calculated using normal controls or from stroke-free areas in the brain of patients. These values were then compared to determine the immediate effect of stroke in a cross-sectional analysis of the data. Subsequent scans were re-analysed to determine the delayed effects in longitudinal analyses of the data. The effects of vascular risk factors, severity of white matter lesions (WML), stroke type and atherosclerosis were also analysed to determine their influence of Aβ deposition.
Results: The overall SUVR of a stroke affected brain does not increase following an infarct when compared to stroke-free controls. However, an increase was noted in the SUVR of the stroke-affected hemisphere and in the region surrounding the stroke when compared to the stroke-free contralateral region in the same patient. This increase in stroke region especially was striking on visual assessment of some PET scans. However, the increase in both stroke-affected hemisphere and the stroke region did not reach statistical significance. When the 11C-PiB-PET was repeated, it was found that the SUVR decreased significantly. This suggested that the initial increase was caused by a transient and reversible process. The most likely explanation for the observation was extravasation of 11C-PiB though a dysfunctional BBB.
Conclusion: The results of this research indicate that it is unlikely that an acute ischaemic infarct triggers deposition of Aβ in the infarct, peri-infarct, ipsilateral cerebral hemisphere or across the brain generally. Furthermore, we were also not able to demonstrate an increase in amyloid in these same brain regions over time. It is unlikely that an acute ischaemic infarct influences amyloid deposition
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
- …
