1,720,954 research outputs found
A new abdominal cavity chamber to study the impact of increased intra-abdominal pressure on micro circulation of gut mucosa by using video microscopy in rats
No full textObjective: In experimental studies of capillary blood flow that use intravital video microscopy, organs are exposed in observation chambers implanted into the animal. In this article we describe an abdominal cavity chamber for intravital video microscopy of gut mucosa microcirculation during increased intra-abdominal pressure. Design: Prospective, experimental animal study. Setting: Research laboratory at a university hospital. Subjects: Male Wistar rats. Interventions: The abdominal cavity chamber was designed for implantation into the abdominal wall of rats after laparotomy, thus creating an expanded hermetic, abdominal cavity volume. Animals were assigned to three levels of intra-abdominal pressure: controls (group 1), 10 mm Hg (group 2), and 15 mm Hg (group 3). Intra-abdominal pressure was increased by intra-abdominal insufflation of gas. By using a fluorescent marker, we quantitatively assessed mucosa perfusion index, functional capillary density, red blood cell velocity, capillary diameters, and flow motion during increased intra-abdominal pressure by intravital video microscopy. Results were expressed as mean SEM. Significance of differences was determined by analysis of variance and multiple comparison of means with post hoc test ( p < .05 groups vs. control; daggerp < .05 group 3 vs. group 2). Measurements and Main Results: When compared with controls, animals subjected to an intra-abdominal pressure of 10 and 15 mm Hg showed a significant stepwise decrease in mucosa perfusion index (88%, 71% , 22% dagger), functional capillary density (665.4 +/- 71.7, 461.6 +/- 71.9 , 375.1 +/- 2.0 dagger cm(-1)), and red blood cell velocity (0.50 +/- 0.04, 0.33 +/- 0.03 , 0.04 +/- 0.06 dagger mm/sec), indicating a stepwise impairment of mucosal microcirculation. Capillary diameters and flow motion did not change with respect to intra-abdominal pressure. Conclusions: This novel animal model of intravital intestinal video microscopy that uses an abdominal cavity chamber is a feasible and sensitive experimental tool to study intestinal microcirculation during increased intra-abdominal pressure. Intra-abdominal pressure likely results in a severe impairment of mucosal microcirculation
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
Vasoactive intestinal polypeptide and gastrin-releasing peptide attenuate hepatic microvasculatory disturbances following intestinal ischemia and reperfusion
No full textBackground/Aims: In addition to the primarily affected small bowel, intestinal ischemia and reperfusion (IIR) also leads to a marked decrease in hepatic microcirculation. The aim was to determine the potentially protective effect of the vasoactive hormones vasoactive intestinal polypeptide (VIP) and gastrin-releasing peptide (GRP) on hepatic microcirculation following IIR. Methods: Using a rat model, three animal groups were subjected to 40 min of intestinal ischemia, two of which were infused with either VIP or GRP (n = 12 each). Following reperfusion, hepatic intravital microscopy was performed. Portal venous perfusion, activities of serum glutamate pyruvate transaminase and alkaline phosphatase, mucosal injury in the small intestine and the expression of antioxidant enzymes glutathione peroxidase, copper-zinc-superoxide dismutase (Cu-Zn-SOD), glutathione reductase and catalase (CAT) in the liver were investigated. Results: Infusion of either VIP or GRP improved hepatic microcirculation and bile flow when compared with the untreated IIR group. VIP and GRP increased portal venous blood flow during reperfusion. VIP reduced the extent of mucosal damage resulting from IIR. GRP caused a decrease in expression of CAT and Cu-Zn-SOD, whereas VIP simply reduced CAT expression. Conclusion: This study indicates that vasoactive hormones may attenuate intestinal and hepatic injuries and circulatory disturbances following IIR. Copyright (C) 2002 S. Karger AG, Basel
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
