1,721,180 research outputs found
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
Melilite-type and melilite-related compounds: structural variations along the join Sr2-xBaxMgSi2O7 (0 <= x <= 2) and high-pressure behavior of the two end-members
No full textThe structural variations along the solid solution Sr2-xBaxMgSi2O7 (0 <= x <= 2), combined to the high-pressure characterization of the two end-members, have been studied. A topological change from the tetragonal (melilite-type) to the monoclinic (melilite-related) structure along the join Sr2MgSi2O7 (e.g., P (4) over bar2(1)m)-)-Ba2MgSi2O7 (e.g., C2/c) occurs with a Ba content higher than 1.6 apfu. Favored in the crystallization from a melt, the tetragonal form has a tetrahedral sheet topology exclusively based on five-membered rings, which provide a regular "4 up + 4 down" ligand arrangement. In contrast, the melilite-related structure, favored by solid-state reaction synthesis, is made by alternating six- and four-membered tetrahedral rings, which give an asymmetric arrangement of alternated "5 up + 3 down" and "3 up + 5 down" ligands around Sr or Ba. This latter configuration is characterized by an additional degree of freedom with Ba polyhedra hosted in the interlayer with a more irregular and compact coordination and longer Ba-O bond distances. Further insights into the relationships between the two melilite typologies were achieved by investigating the in situ high-pressure behavior of these systems. The synchrotron high-pressure experiments allowed to calculate the elastic moduli for the Sr melilite-type end-member and for the Ba monoclinic polymorph (Sr2MgSi2O7: K (T0) = 107, K (a=b) = 121, and K (c) = 84 GPa; m-Ba2MgSi2O7: K (T0) = 85, K (a) = 96, K (b) = 72, and K (c) = 117 GPa) and compare them with those reported in the literature for Ayenkermanite (Ca2MgSi2O7). The results show that, although the volume of Ba polyhedron in tetragonal polymorphs is larger than in the monoclinic forms, the interlayer compressibility is significantly lower in the former structures due to the occurrence of very short Ba-O distances. This unfavored Ba environment also makes tetragonal Ba2MgSi2O7 a metastable phase at room conditions, possibly favored by high pressure. However, no phase transition occurs from monoclinic to tetragonal form due to kinetic hindrance in reconstructing the sheet topology
Multiple titanium substitutions in biotites from high grade metapelitic xenoliths (Euganean Hills, Italy): full crystal chemistry and appraisal of petrologic control, American Mineralogist
No full textPrincipal properties for aromatic substituents. A multivariate approach for design in QSAR
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