1,720,960 research outputs found
Helicobacter pylori (HP) eradication does not influence the natural history of gastric precancerous changes
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Helicobacter pylori and the liver: any relationship?
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Helicobacter pylori infection is being correlated to a number of human diseases, among which also those of the liver. From a clinical point of view, 4 "areas of interest" for the suggested correlation can be identified: 1. Helicobacter pylori and portal hypertension-related congestive gastropathy in cirrhotics. There are, in the literature, at least 7 studies confirming that the microorganism has no role in causing or worsening the disease. 2. Helicobacter pylori and duodenal ulcer in cirrhotic patients. Apparently, in the cirrhotic patient, the microorganism has no role in causing duodenal ulcer. 3. Helicobacter pylori, ammonia production and hepatic encephalopathy. In this case, there are at least three studies showing that Helicobacter pylori infection increases the risk of developing encephalopathy in the cirrhotic patient, this being a somewhat expected finding. 4. Helicobacter pylori infection in chronic liver disease and its diagnosis. Evidence in the literature suggests: a) that hypertensive gastropathy might not represent a favourable environment for Helicobacter pylori thus making the diagnostic sensitivity of the biopsy lower than expected, and b) that even serological diagnosis might provide data of difficult interpretation, as shown in non alcoholic cirrhosis and, by our own group, in primary biliary cirrhosis. More intriguing are the data generated with respect to the potential capacity of Helicobacter pylori and Helicobacter pylori-like bacteria such as, in particular, Helicobacter hepaticus to damage the liver by producing toxins with a granulating effect on liver cell lines which, in vivo, through the portal tract, might reach the liver, thus causing hepatocellular damage. The point has been addressed by a number of investigators and autoimmune mechanisms have also been suggested. In summary, from the clinical point of view, some evidence suggests that Helicobacter pylori infection might be relevant in the pathogenesis of hepatic encephalopathy in cirrhosis. The data being generated with respect to a direct hepatotoxicity are, at present, stimulating but only speculative
Anti-VacA antibody production by peripheral blood mononuclear cells (PBMC) of patients with and without Helicobacter pylori (Hp) infection.
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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
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