1,721,018 research outputs found
La nature des fluides hydrothermaux des tourmalinites du massif granitique permien du Ment (Maroc central). Couplage de la minéralogie des tourmalines et de l'étude des inclusions fluides
No full textThe Permian Ment massif is famous for its hydrothermal alterations. The massif comprises a main intrusion of biotite granodiorite and several minor peraluminous granite plutons, both affected by the whole spectrum of alterations. In addition, the surrounding Namurian-Westphalian flyschs display huge bodies of massive tourmalinites.
Two alteration styles are recognized : (i) early quartz-stable associations (greisens, quartz-tourmalinites) developed at ca. 500 °C and 50 MPa from C02-rich C-O-H-N fluids, and (ii) later quartz-unstable assemblages (muscovitites, tourmalinites).
Late stage hydrothermalism was studied combining a classical microthermometric fluid inclusion study and a detailed mineralogi-cal study of zoned tourmaline crystals (SEM, electron microprobe). Late tourmalinisation occurred in a high enthalpy geothermal system at low pressure and high temperature (ca. 400 ° to 200 °C, 30 to 10 MPa), and was driven by mixing processes between threee hydrothermal end-members : a magmatic fluid, a fluid derived from the metamorphic surrounding rocks and a surficial fluid infiltered at various depths in the granite masses and experiencing re-equilibration with the granite rocks. Mixing proportions were extremely variable in time and space, being controlled by episodic tectonic activity.Le pluton du Ment, d'âge permien, est remarquable par l'importance et la diversité de ses altérations hydro thermales, de même âge. Ces altérations affectent l'encaissant (tourmalinisation des flyschs namuro-westphaliens de l'auréole de contact) et les deux lignées de granitoïdes qui forment le massif : granodiorite à biotite (masse principale) et leucogranites peralumineux. Deux épisodes hydrothermaux se sont succédés : altérations à quartz stable (greisens, quartz-tourmalinites), développées à ca. 500 °C et 50 Mpa par des fluides aquo-carboniques, et al.érations à quartz instable (muscovitisation, tourmalinisation). L'étude de ces dernières a été effectuée en combinant la microthermométrie des inclusions fluides et la minéralogie détaillée des tourmalines zonées (MEB, Microsonde électronique). Il apparaît que la tourmalinisation tardive s'est faite dans les conditions d'un champ géothermique de haute enthalpie (températures jusqu'à 400 °C et plus, profondeur kilométrique) et implique des mélanges entre trois pôles hydrothermaux : un fluide magmatique, un fluide issu de l 'auréole de contact et un fluide superficiel percolant dans les granites avec lesquels il s 'équilibre. Ces mélanges se font en proportion variable dans l 'espace et dans le temps, en fonction de l 'activité tectonique qui rythme les circulations et détermine les drains majeurs.Bouabdellah Mohamed, Marignac Christian. La nature des fluides hydrothermaux des tourmalinites du massif granitique permien du Ment (Maroc central). Couplage de la minéralogie des tourmalines et de l'étude des inclusions fluides. In: Collection EDYTEM. Cahiers de géographie, numéro 9, 2009. L’hydrothermalisme en domaine continental. Fonctionnement, ressource et patrimoine. pp. 33-48
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
Datation par les méthodes K/Ar et Rb/Sr de quelques roches de la partie orientale de l'Ile d'Elbe (Province de Livourne, Italie)
No full textRadiometric dating of the Quartz-monzonite of Porto Azzurro (Elba Island, Italy) gave ages of 5.9 ± 0.5 M.y. (K/Ar) and of 5.1 M.y. (Rb/Sr). Similar K/Ar ages were obtained for the biotite (6.2 ± 0.5 M.y.) and the K-feldspar (5.4 ± 1.1 M.y.) from one sample of this rock. The quartz-monzonite intrusion produced a hydrothermal metamorphism (amphibolite at 6.6 ± 0.9 — KAr) and a contact metamorphism. The later is deduced from K/Ar ages of the « Scisti di Calamita » (5.1 ± 0.6 M.y.) and of three aplite-swarms giving respectively 5.2 ± 0.7, 5.7 ± 0.4 and 6.1 ± 1.1 M.y.Des datations nouvelles de la quartz˗monzonite de Porto-Azzurro (Ile d'Elbe, Italie) ont donné des âges de 5,9 ± 0,5 M.a. (K/Ar) et de 5,1 M.a. (Rb/Sr), concordants avec les âges K/Ar obtenus sur la biotite (6,2 ± 0,5 M.a.) et le feldspath potassique (5,4 ± 1,1 M.a.) d'un échantillon de cette roche. L'intrusion de quartz˗monzonite a été accompagnée d'un métamorphisme hydrothermal (amphibolite hydrothermale : 6,6 ± 0,9 M.a. — K/Ar) et d'un métamorphisme thermique donné par les âges K/Ar des Schistes de Calamita (5,1 ± 0,6 M.a.) et de trois essaims d'aplites (5,2 ± 0,7 ; 5,7 ± 0,4 et 6,1 ± 1,1 M.a. respectivement).Saupé Francis, Marignac Christian, Moine Bernard, Sonet Jacques, Zimmermann Jean-Louis. Datation par les méthodes K/Ar et Rb/Sr de quelques roches de la partie orientale de l'Ile d'Elbe (Province de Livourne, Italie). In: Bulletin de Minéralogie, volume 105, 3, 1982. pp. 236-245
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
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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