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Annual variations in the binding of insulin to hepatic membranes of the frog Rana esculenta
No full textGlycogen phosphorylase activity in the liver of the frog Rana esculenta
No full text1. Phosphorylase activity has been assayed in liver extracts of the frog, Rana esculenta, during the winter period. In native conditions, most of the phosphorylase is present as AMP-independent activity and shows properties similar to those of the a form of the liver enzyme from other vertebrates.
2. It is suggested that regulation of phosphorylase activity is through interconversion between a and b forms operated by endogenous phosphorylase kinase and phosphatase.
3. Kinetic studies show hyperbolic saturation curves for glycogen with apparent K(m) of 2.91 mM and 9.67 mM for a and b forms, respectively.
4. A hyperbolic saturation curve is also observed for glucose I-P in the case of phosphorylase a, with an apparent K(m) of 3.95 mM, whereas a sigmoidal kinetic is shown by the b form for the same substrate; from Hill plots an S0.5 of 24.2 mM was derived.
5. Hyperbolic responses were observed in the case of AMP, and K(a) of 70 muM and 0. 31 mM were calculated for phosphorylase a and b, respectively
Seasonal variations of glycogen synthase and phosphorylase activities in the liver of the frog Rana esculenta
No full textGlycogen metabolism has been studied in the liver of the frog Rana esculenta throughout the annual cycle. Hepatic glycogen reserves are high during winter and decrease during spring and summer, the changes being reflected by variations in the activities of the rate-limiting enzymes glycogen synthase and phosphorylase. Glycogen deposition is associated with increased levels of synthase D activity and no changes in the relative proportions of the active-inactive form of the enzyme, whereas during glycogen mobilization significant changes in both total phosphorylase and in the percent phosphorylase a are observed. Regression analysis indicates a positive correlation between glycogen content and synthase activity, and an inverse relationship between glycogen content and either total phosphorylase or phosphorylase a. The results suggest that glycogen deposition and/or mobilization could be mainly controlled by mechanisms related to either changes in the amount of enzyme protein or to allosteric effects of the metabolite glucose-6-phosphate on glycogen synthase and phorphorylase
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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