1,720,956 research outputs found
Oxygen supply, body size, and metabolic rate at the beginning of mammalian life
No full textTo test the relationship between hypoxia/ischemia tolerance and metabolic rate in neonatal tissues, isolated unperfused hearts of neonatal, juvenile, and adult mice were studied by microcalorimetry and microrespirometry. Additionally, microslices of mouse hearts were prepared and studied in a microcalorimeter under different oxygenation conditions. Neonatal hearts had a slower hypoxic/ischemic decline in heat output than adult organs, correlated with a higher uptake of physically dissolved oxygen from the incubation solution. In the slice experiments, the neonatal samples were found to exhibit a higher metabolic activity which enables them to maintain, at low pO(2), a similar metabolic rate as the adult tissue at high pO(2). This corresponds to the fetal adaptation to low intrauterine oxygen tensions and might be a common basis for the elevated neonatal hypoxia/ischernia tolerance as well as for the postnatal increase in metabolic rate up to the level to be expected from body size. (C) 2002 Elsevier Science B.V. All rights reserved
Body size effects on tissue metabolic rate and ischemia tolerance in neonatal rat and mouse hearts
No full textAlthough the specific basal metabolic rate increases with decreasing body mass, newborn mammals are known to exhibit a higher tolerance to hypoxia/ischemia than adults. This is partly due to their ability to reduce energy demands in response to impaired supply. The so-called "hypoxic hypometabolism" might be explained as a temporary return to a prenatal metabolic state where the usual metabolic size relationship is suppressed and the fetus exhibits an "adult-like" specific metabolic rate. To study the interrelationship of body size, metabolic rate, and ischemia tolerance within and across species, both myocardial thin slices (to determine aerobic metabolic rates) and isolated non-perfused hearts (to assess ischemic "dying curves") from neonatal, juvenile, and adult rats were measured by microcalorimetry (2277 Thermal Activity Monitor, ThermoMetric, Sweden) and the results compared with earlier findings on mouse hearts. The aerobic tissue metabolic rates of myocardial samples from both species decreased with increasing body mass, according to the overall metabolic size relationship. Moreover, a slowing-down of the ischemic "dying curves" with decreasing body mass was found, reflecting the increasing hypoxia/ischemia tolerance. However, the amount of heat produced during ischemia turned out to be higher in neonatal rats than in juvenile mice, or in juvenile rats than in adult mice, respectively, despite nearly identical body and organ weights. The factor by which the ischemia tolerance of rats exceeds that of mice of comparable size, corresponds to the difference in specific basal metabolic rates to be expected between adult individuals of the same species. This is suggestive of a temporary return to an "adult-like" metabolic level underlying the elevated hypoxia/ischemia tolerance in neonatal and juvenile mammals. (C) 2004 Elsevier B.V. All rights reserved
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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