1,721,005 research outputs found
The affinities of Chordecystia chalasta Foster, and its questionable use as a global chronostratigraphic marker for the Permian-Triassic boundary
No full text
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
Crystal structure of glutamate-1-semialdehyde. An alpha-2-dimeric vitamin B6 dependent enzyme with asymmetry in structure and active site reactivity
No full textABSTRACT The three-dimensional structure of glutamate-
1-semialdehyde aminomutase (EC 5.4.3.8), an a2-
dimeric enzyme from Synechococcus, has been determined by
x-ray crystallography using heavy atom derivative phasing.
The structure, refined at 2.4-Å resolution to an R-factor of
18.7% and good stereochemistry, explains many of the enzyme’s
unusual specificity and functional properties. The
overall fold is that of aspartate aminotransferase and related
B6 enzymes, but it also has specific features. The structure of
the complex with gabaculine, a substrate analogue, shows
unexpectedly that the substrate binding site involves residues
from the N-terminal domain of the molecule, notably Arg-32.
Glu-406 is suitably positioned to repel a-carboxylic acids,
thereby suggesting a basis for the enzyme’s reaction specificity.
The subunits show asymmetry in cofactor binding and in
the mobilities of the residues 153–181. In the unliganded
enzyme, one subunit has the cofactor bound as an aldimine of
pyridoxal phosphate with Lys-273 and, in this subunit, residues
153–181 are disordered. In the other subunit in which the
cofactor is not covalently bound, residues 153–181 are well
defined. Consistent with the crystallographically demonstrated
asymmetry, a form of the enzyme in which both
subunits have pyridoxal phosphate bound to Lys-273 through
a Schiff base showed biphasic reduction by borohydride in
solution. Analysis of absorption spectra during reduction
provided evidence of communication between the subunits.
The crystal structure of the reduced form of the enzyme shows
that, despite identical cofactor binding in each monomer, the
structural asymmetry at residues 153–181 remains
Crystallization and preliminary X-ray analysis of gamma-aminobutyric acid transaminase
No full textgamma-Aminobutyric acid transaminase from pig liver, an alpha 2 dimeric enzyme of Mr 110,100, has been crystallized by the vapour diffusion method with polyethylene glycol as precipitant. The crystals are monoclinic, space group P2(1), unit cell dimensions a = 82.1 A, b = 230.0 A, c = 70.3 A, beta = 123.9 degrees and diffract to 2.5 A resolution. There are two dimers per asymmetric unit
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
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