1,721,036 research outputs found
Palynological evidences for abrupt climatic changes in the Piacenzian strtotype (Piacenza, Northern Italy)
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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
The classical Late Piacenzian Monte Falcone – Rio Crevalese section (Northern Italy): palynological evidence and biomagnetostratigraphic constraints for climatic ciclicity and local mollusc extinctions
No full textImproved method for the analysis of alditols in confectionery products by capillary zone electrophoresis (CZE) - comparison with high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD)
No full textAlditols, usually employed as low-calorie swweteners in chewing gum and confectionery products, were determined by a rapid and highly efficient capillary zone electrophoretic method using direct UV detection at 200 nm. With a running electrolyte containing borate, alditols are readuly converted to anionic borate complexes, allowing their selective electromigration. The influence of various separation conditions, including buffer composition, pH, voltage and temperature were investigated to select the optimum conditions. Furthermore, the CZE method was compared with t aprevious developed HPAEC method coupled to PAD in terms of repeatability, separation efficiency, linearity, sensititvity and accuracy
Compositional analysis of the major capsular polysaccharides of Cryptococcus neoformans by high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD)
No full textCryptococcus neoformans is a predominantly saprophytic yeast that can cause serious infections, mostly in individuals with acquired immunodeficiency syndrome (AIDS).
A prominent virulence factor of Cryptococcus neoformans is its capsule. This is constituted mainly of glucans; the capsular polysaccharide, glucuronoxylomannan (GXM) (composed of mannose, xylose, glucuronic acid), and at least two minor carbohydrate antigens, galactoxylomannan (GalXM) and mannoproteins (MP).
In this paper we present an optimized HPAEC-based method for the rapid and effective determination of the complete carbohydrate constituents of GXM and GalXM.
Cryptococcus neoformans strain A 9759 serotype A and the acapsular mutant CAP 67 were grown in a totally dialyzable synthetic medium at 30 degrees C. Culture supernatants were subjected to tangential filtration (10,000-M-r-cut-off) to separate high molecular weight cryptococcal products from medium constituents.
The supernatants were dialyzed against phosphate buffer saline (PBS) containing sodium azide (0.02%) and concentrated to a carbohydrate concentration of 1.5 mg/mL. GXM and GalXM were isolated and purified as described in the experimental section. For neutral sugar and uronic acid composition analysis, 2.5 mg polysaccharide fractions were hydrolyzed with 2 M trifluoroacetic acid (TFA, 100 degrees C, 6 h), followed by lyophilization, then the residues were analyzed by HPAEC coupled with pulsed amperometric detection (PAD).
Separations were carried out using either a CarboPac PA 100 or a CarboPac PA 10 column and matching guard column (all from Dionex, Sunnyvale, CA, USA). Employing PA 100, as well as PA 10 column, baseline separation of the neutral monosaccharides galactose, glucose, xylose, mannose and glucuronic acid were obtained. Monosaccharide and uronic acid compositions of GXM and GalXM determined by this method were found to be highly accurate
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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