1,721,494 research outputs found
Russell Mark Rector
No full textOn April 14, 2019, Russell Mark Rector, beloved son and brother, passed away unexpectedly at his home in Oakland. Born in Oakland in 1953, Russell was a wonderful gift to his parents, Robert and Marcia. He grew up in Palo Alto, graduating in 1970 from Palo Alto High School, where he was a National Merit Scholar
Studies on the uroporphyrinogen decarboxylase and corproporphyinogen III oxidase of the photosynthetic bacterium, Rhodobacter sphaeroides
No full textUroporphyrinogen decarboxylase and coproporphyrinogen III oxidase were studied in the photosynthetic bacterium, Rhodobacter sphaeroides. Uroporphyrinogen decarboxylase was purified, 600 fold, to homogeneity in yields of 40%. Uroporphyrinogen decarboxylase was found to be a monomer of Mr 41,000, both under denaturing and non-denaturing conditions. Analysis of the absorbtion spectrum of the enzyme gave a single peak at 280 nm with no evidence for any chromomorphic cofactors, while determination of the pH optimum and isoelectric point revealed values of 6.8 and 4.3, respectively. Kinetic studies have revealed a Km of 1.8 μM and 6.0 μM for the conversion of uroporphyrinogen I and III, to coproporphyrinogen I and III, respectively. The enzyme was susceptible to inhibition by its substrates at high concentrations and by the presence of porphyrins, especially the oxidised product, coproporphyrin III. Further investigations have shown the enzyme to be inhibited by metal ions, particularly mercury, which implicate the involvement of a cysteine residue. This observation is confirmed by the inhibition of activity by sulphydryl reagents. Titration of cysteine residues with DTNB has revealed five residues, one of which has been shown to be important for the activity of the enzyme. Arginine and to a lesser extent lysine residues have also been implicated in activity. Uroporphyrinogen decarboxylase was found to be inactivated at temperatures above 45oC. The amino acid sequence for the first thirty residues of the N-terminus have been determined. The pathway of decarboxylation of uroporphyrinogen III to coproporphyrinogen III by uroporphyrinogen decarboxylase was also investigated. A mutant of R. sphaeroides, N1, has been isolated by its inability to grow under conditions of limiting oxygen in the light, while growth under chemoheterotrophic conditions, was unaffected. The inability to grow under photosynthetic conditions was accompanied by the excretion of coproporphyrin III into the media. Analysis by h.p.l.c. and direct enzyme assay has determined that the N1 mutant contains a defective coproporphyrinogen III oxidase. The N1 locus, which contains an open reading frame of 1.2 kb encoding a polypeptide of 307 amino acids, has been isolated and cloned into the pUC18/19 expression system and has resulted in a 2.4 fold increase in coproporphyrinogen III oxidase activity in E. coli. It is therefore proposed that this locus contains the putative hemF gene, which encodes the anaerobic coproporphyrinogen III oxidase.</p
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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