1,720,966 research outputs found
Sur l'existence et la signification minéralogique d'une variété de laumontite dans le cirque de Cilaos (île de la Réunion)
No full textNativel Pierre. Sur l'existence et la signification minéralogique d'une variété de laumontite dans le cirque de Cilaos (île de la Réunion). In: Bulletin de la Société française de Minéralogie et de Cristallographie, volume 97, 1, 1974. pp. 82-84
Découverte de thénardite dans les dépôts fumerolliens de la Fournaise (île de la Réunion)
No full textNativel Pierre. Découverte de thénardite dans les dépôts fumerolliens de la Fournaise (île de la Réunion). In: Bulletin de la Société française de Minéralogie et de Cristallographie, volume 95, 4, 1972. pp. 529-531
Apport de l'analyse ionique à l'étude minéralogique d'une ignimbrite à chimisme de benmoréite du Cirque de Salazie (île de la Réunion)
No full textA qualitative account of all the minerals founded in an ignimbrite with benmoreite chemistry of Reunion Island has been drawn up by ion microanalyser. The electron microprobe has specified their composition. Two pyroxenes with a high calcium content (salite and hedenbergite) coexist with an hour-glass zoned anorthoclase.
On another hand, quantitative analyses have been performed for the first time, by means of the ion microanalyser on salite, anorthoclase and mesostase of matrix or fiammes.Dans une ignimbrite à chimisme de benmoréite de la Réunion, un bilan qualitatif des minéraux présents a été dressé par l'analyseur ionique. La microsonde électronique a précisé leur composition. Deux pyroxènes riches en calcium, une salite et une hédenbergite, coexistent avec une anorthose à zonations en sablier.
D'autre part, des analyses quantitatives ont, pour la première fois, été effectuées à l'aide du microanalyseur ionique sur la salite, l'anorthose et la mésostase de la matrice ou des fiammes.Havette Ledebt Andrée, Nativel Pierre. Apport de l'analyse ionique à l'étude minéralogique d'une ignimbrite à chimisme de benmoréite du Cirque de Salazie (île de la Réunion). In: Bulletin de la Société française de Minéralogie et de Cristallographie, volume 100, 1, 1977. pp. 20-27
Une paragenèse inhabituelle à fassaïte, mélilite et rhönite dans un basalte alcalin contaminé au contact d'un récif corallien (Saint-Leu, Ile de la Réunion)
No full textThe amount of calcium assimilated by the basaltic lavas, the oxygen fugacity and thermal gradient controlled the distribution of secondary mineral assemblages in these basalts depending on proximity to contaminating coral rocks. Within corallites, melilite has crystallized before fassaïte and rhönite, while a few centimeters away from coral skeletons, fassaïte was first generated, replacing basalt pyroxenes partly or completely. Rhönite is absent in this zone.
The chemical compositions of fassaïte and rhönite can easily be distinguished from previous data presented in literature on earth [= onshore] rocks : undersaturation in silica, higher Fe-Ti contents. The associated minerals have crystallized at high temperature (1 000 °C), total fluid pressure being close to the atmospheric one and high CO₂ fugacity.La proportion de calcium assimilé par la lave, la fugacité d'oxygène et le gradient de température conditionnent les paragenèses observées à différentes distances du récif contaminant. A l'intérieur des septes du corail, la cristallisation de la mélilite précède celle de la fassaïte et de la rhönite alors qu'à plus grande distance du contact (quelques centimètres) c'est la fassaïte qui cristallise d'abord, remplaçant partiellement ou totalement les pyroxènes du basalte. La rhönite est absente dans cette zone.
Les compositions chimiques des fassaïtes et des rhönites se distinguent de celles données dans la littérature pour les roches terrestres : sous-saturation en silice, teneur élevée en fer pour les rhönites et en titane pour certaines fassaïtes. Cette paragenèse a cristallisé à une température voisine de 1 000 °C, pression totale des fluides voisine de la pression atmosphérique et fugacité de CO₂ élevée.Havette Ledebt Andrée, Clocchiatti Roberto, Nativel Pierre, Montaggioni Lucien François. Une paragenèse inhabituelle à fassaïte, mélilite et rhönite dans un basalte alcalin contaminé au contact d'un récif corallien (Saint-Leu, Ile de la Réunion). In: Bulletin de Minéralogie, volume 105, 4, 1982. pp. 364-375
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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