1,721,006 research outputs found
On melt crystallization of polytetrafluoroethylene and of random fluorinated copolymers of tetrafluoroethylen
No full textOn crystallization kinetics of polytetrafluoroethylene and of random tetrafluoroethylene fluorinated copolymers
No full textTaxonomic discrimination of Raja polystigma and Raja montagui in the Mediterranean Sea based on the comparative analysis of morphometric and genetic markers
No full textIn the last years many studies based only on morphological features revealed a diffuse uncertainty in the taxonomic discrimination between individuals of Raja montagui (distributed in the NE Atlantic and Mediterranean) and Raja polystigma (endemic of the Mediterranean). This could be related to the inappropriateness of the morphological characters reported in the identification keys used to distinct the two species. The achievement of reliable tools for the identification of the two species will be useful for improving life-history traits and species assessment. The nucleotide variation of the species-specific gene marker 16S rDNA was analysed for 115 individuals collected in NE Atlantic and in different areas of the Mediterranean basin (Adriatic Sea, Thyrrenian Sea, Sardinian Channel, Sicily Channel and Algeria) and morphologically recognized as Raja montagui and R. polystigma. 79 individuals were identified bearing the R. polystigma haplotype and 9 individuals bearing the R. montagui haplotype. A second R. polystigma haplotype was found in 27 individuals from the Thyrrenian Sea. Among the 75 individuals collected in the Italian Seas, none showed a 16S R. montagui haplotype. Many incongruence between morphological appearance and mitochondrial haplotypes were observed in these specimens. Among the 16S-genotyped individuals, dorsal and ventral digital pictures were taken on about 60 individuals. The software used for the shape analysis allowed easy measurement and included advanced graphical capabilities for the visualization of morphometric data and results. 14 and 22 relevant landmarks were chosen, respectively on the dorsal and ventral side of the ray. 33 distances and 5 angles were calculated for each sample. Moreover, the main dorsal spines row and the upper and lower teeth rows were measured. No clustering of individuals according to species boundaries was observed. These preliminary results seem to indicate that R. montagui is not probably present in the Italian seas and, within the Mediterranean, it is present along the Algerian coasts
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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