1,720,962 research outputs found
Géochimie et thermodynamique des évaporites continentales. Etude du lac Natron en Tanzanie et du Chott El Jerid en Tunisie
No full textGueddari Moncef. Géochimie et thermodynamique des évaporites continentales. Etude du lac Natron en Tanzanie et du Chott El Jerid en Tunisie. Strasbourg : Institut de Géologie – Université Louis-Pasteur, 1984. 164 p. (Sciences Géologiques. Mémoire, 76
Geochemistry of silica-rich brines from Lake Natron (Tanzania). Géochimie des saumures riches en silice du lac Natron (Tanzanie)
No full textA computer program has been developed for calculating the activity coefficients of aqueous silica species. This program allows to the testing of the saturation states of silicate minerals in solutions concentrated by evaporation, particularly in alkaline brines. This has been done first for water samples from the Lake Natron basin. In these solutions due to evaporative concentration and/or temperature increase, magnesium is strongly depleted in the early stage of the evaporative salinization and magnesium silicates like sepiolite or magnesium-calcite may precipitate. At the end of the evaporitive process, the sodium and silica concentration increase regularly with the pH, and saturation with respect to magadiite and kenyaite is reached. However this does not affect the water chemistry, and the activity of silica is only limited by amorphous silica control. Therefore amorphous silica formation can be considered as the possible origin for the great amounts of cherts found in this basin.Un programme de calcul a été développé pour calculer le coefficient d'activité des espèces aqueuses de la silice. Ce programme permet de tester l'état de saturation des minéraux silicatés dans des solutions se concentrant par évaporation, et plus particulièrement dans des solutions alcalines. Ceci a été mis en application pour les échantillons du bassin du lac Natron. Dans les premiers stades d'évolution de ces solutions, le magnésium décroît fortement par concentration évaporitique et/ou en relation avec l'augmentation de la température, et un silicate de magnésium comme la sépiolite ainsi qu'une calcite magnésienne peuvent précipiter. D'autre part, dans les derniers stades d'évolution du processus évaporitique, les concentrations en sodium et silice augmentent régulièrement en relation avec l'augmentation du pH, et l'état de saturation vis-à-vis de la magadiite et de la kenyaite est atteint. Mais ceci ne semble apparemment pas affecter la chimie de l'eau, et l'activité de la silice est seulement limitée par la saturation par rapport à la silice amorphe, dont la formation par précipitation directe peut être considérée comme une origine possible pour les grandes quantités de cherts trouvés dans le bassin.Fritz Bertrand, Zins-Pawlas Marie-Paul, Gueddari Moncef. Geochemistry of silica-rich brines from Lake Natron (Tanzania). Géochimie des saumures riches en silice du lac Natron (Tanzanie). In: Sciences Géologiques. Bulletin, tome 40, n°1-2, 1987. Lac Natron. Géologie, géochimie et paléontologie. D'un bassin évaporatique du rift est-africain. pp. 97-110
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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