1,721,050 research outputs found
Crystallographic and biochemical analysis of three distinct hydrolases : Dermatophagoides pteronyssinus 1 (Der p1), momordin and the bacterial carbon-carbon hydrolase, MhpC
No full textMhpC is one of six enzymes derived from the mhp operon, which collectively give rise to meta-cleavage pathway for the degradation of 3-(3-hydroxyphenyl)propionic acids (3-HPP) in Escherichia coli. These enzymes work in tandem to convert 3-HPP to metabolites which can then be fed into the Kreb's cycle for energy release. The role of MhpC in this pathway is to convert 2-hydroxy-6-ketonona-2,4-diene-1,9-dioate to 2-hydroxy-penta-2, 4-dienoate and succinate. This reaction involves the breaking of a carbon-carbon bond, which constitutes a rare catalytic event in nature. Elucidating the catalytic mechanism of MhpC will provide invaluable information at the molecular level contributing to the understanding of how biodegradation of environmental pollutants can be achieved.The MhpC structure has been solved using Multiwavelength Anomalous Dispersion (M.A.D.) phasing to obtain the protein phase information from 32 selenomethionine sites in the MhpC asymmetric unit. The enzyme belongs to the α/β hydrolase fold family. Mechanistic studies can now be undertaken involving the analysis of the interactions of various ligands bound in at the active site.Momordin is a ribosome inactivating protein (RIP) from the seeds of the bitter gourd, Momordica charantia. RIPs exist in two main classes. Type II RIPs, such as ricin, possess two subunits, the A- and B-chains. The A-chain is a toxin which targets ribosomes, whilst the B-chain is a lectin responsible for facilitating A-chain entry into cells. Type 1 RIPs, in contrast, are monomeric toxins, which share homology with type II RIP A-chains.</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
On a conjecture of Erdős, Graham and Spencer
No full textAbstractIt is conjectured by Erdős, Graham and Spencer that if 1⩽a1⩽a2⩽⋯⩽as with ∑i=1s1/ai<n−1/30, then this sum can be decomposed into n parts so that all partial sums are ⩽1. This is not true for ∑i=1s1/ai=n−1/30 as shown by a1=2, a2=a3=3, a4=⋯=a5n−3=5. In 1997, Sándor proved that Erdős–Graham–Spencer conjecture is true for ∑i=1s1/ai⩽n−1/2. In this paper, we reduce Erdős–Graham–Spencer conjecture to finite calculations and prove that Erdős–Graham–Spencer conjecture is true for ∑i=1s1/ai⩽n−1/3. Furthermore, it is proved that Erdős–Graham–Spencer conjecture is true if ∑i=1s1/ai<n−1/(logn+loglogn−2) and no partial sum (certainly not a single term) is the inverse of an positive integer
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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