1,721,101 research outputs found
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
Mineralogical and geochemical characterization and diagenetic evolution of siliciclastic intracontinental mesoproterozoic basins : implications for the genesis of unconformity-related uranium deposits
No full textUne étude pétrographique, minéralogique et géochimique des bassins sédimentaires silicoclastiques intracontinentaux protérozoïques de Waterberg (Craton de Kaapvaal, Afrique du Sud), Cariewerloo (Craton de Gawler, Sud de l'Australie), Satakunta et Muhos (Bouclier Fennoscandien, Finlande), reposant en discordance sur un socle paléoprotérozoïque à archéen, a été réalisée. Une comparaison avec d’autres districts du monde d’âge et de lithologie semblables (le bassin d’Athabasca au Canada, le bassin de Kombolgie en Australie et le bassin de Pasha- Ladoga en Russie) auxquels sont associés les gisements d’uranium de type discordance les plus importants. Les études réalisées ont permis de reconstituer la nature des phases détritiques et leur évolution au cours de la diagenèse et des événements hydrothermaux, afin d’évaluer l’intérêt que représentent les sédiments de ces bassins pour l’exploration d’uranium par comparaison avec les bassins fortement minéralisés de l’Athabasca et de Kombolgie. Cette étude montre que les sédiments clastiques de tous ces bassins sont caractérisés par une forte immaturité des matériaux sédimentaires, une forte oxydation, ainsi qu’une diagenèse ou un métamorphisme de haute température. Ces sédiments riches en feldspath potassique et plagioclase avec fréquemment des clastes anguleux résultent d’un transport court depuis une zone source peu soumise à l’altération pédogénétique dans un contexte tectonique très actif, contrairement aux sédiments de l’Athabasca et de Kombolgie. Toutefois, des circulations importantes de fluides ont été mises en évidence au toit des socles des bassins de Cariewerloo et à un degré moins important à Satakunta et à Muhos, comme l’indique l’altération argileuse de ces roches. Cette altération étant toutefois modérée par rapport à celle observée dans les bassins de l’Athabaska et de Kombolgie. Ces circulations de fluides ont conduit à l’altération de zircon, ainsi qu’à la formation de chlorites ferrifères et de carbonates.A mineralogical, petrographic and geochemical study of the proterozoic siliciclastic sedimentary intracontinental basins of Waterberg (Kaapvaal Craton, South Africa), Cariewerloo (Gawler Craton, South Australia), Satakunta and Muhos (Fennoscandian Shield, Finland), unconformably overlying archaean and paleoproterozoic basement, have been characterized and compared with other districts throughout the world similar in age and lithology (the basin of Athabasca in Canada, the basin of Kombolgie in Australia, and the basin of Pasha-Ladoga in Russia) which are associated with uranium ore deposits. The realized study made it possible to reconstitute the nature of the detrital phases and their evolution during diagenesis and hydrothermal events, in order to evaluate the interests that represent the sediments of these basins for the exploration of uranium by reference to strongly mineralized Athabasca and Kombolgie basins. This study shows that the clastic rocks of all of these basins are characterized by a high immaturity of sedimentary materials, a strong oxidation, as well as a diagenesis or a metamorphism of high temperature. These sediments, rich in potassic feldspar and plagioclase with frequently angular clasts, were transported over a short distance from the source area and subjected to a limited pedogenic alteration in a very active tectonic context, contrary to the sediments of the Athabasca and Kombolgie basins. However, significant fluid circulations took place as shown by the presence of an argillaceous alteration on the roof of the basement of the Cariewerloo, Satakunta and Muhos basins, as the argillaceous alteration. This alteration remains however moderate compared to that observed in the Athabasca and Kombolgie basins. These fluid circulations are related to zircon alterations, and essentially to the formation of Fe-chlorite and carbonate
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
Sodium metasomatism associated to uranium mineralization : examples of Kirovograd - Novoukrainsk district (Ukraine), Kurupung batholith (Guyana) and Espinharas ore deposit (Brazil)
No full textLes gisements uranifères Protérozoïques du batholite du Kurupung (2041 ± 29 Ma) situés au Nord-Ouest du Guyana et du district de Kirovograd - Novoukrainsk (granite de Novoukrainsk daté à 2047 ± 19 Ma) situés en Ukraine sont des occurrences où la minéralisation (présente sous la forme d’uraninite, pechblende, oxyde de U-Ti) est associée à une métasomatose sodique. Elles semblent appartenir à un évènement métallogénique Paléoprotérozoïque majeur nouvellement caractérisé dans le cadre de ce travail, et auquel appartiendraient aussi des minéralisations similaires du Sud marocain et de Lagoa Real au Brésil. Le gisement d’Espinharas situé au Brésil, associé aussi à une métasomatose sodique, présente une minéralisation uranifère principalement visible sous la forme de cristaux de coffinite, d’oxyde d’uranium et d’uranothorite. Cette altération hydrothermale se développe selon différents stades : (i) une albitisation avec remplacement isomorphique de l’orthose et du plagioclase par de l’albite puis une dissolution complète du quartz de la roche ; (ii) une cristallisation d’albite automorphe dans les cavités laissées par le quartz suivie par (iii) une cristallisation de minéraux calciques (calcite, épidote, pyroxène), de minéraux d’uranium (uraninite et/ou pechblende et/ou brannérite et/ou oxyde de U-Ti selon les gisements), de zircons hydrothermaux, de chlorite, et parfois de quartz secondaire. Les études isotopiques (delta18Oalbite compris entre 2,2 et 2,9 ‰ pour les albitites d’Ukraine et delta18Oalbite et delta18Ocalcite compris entre 2,8 et 5,3 ‰ pour des albitites du Guyana) et microthermométriques (Th > 350°C) ont permis de montrer que le fluide hydrothermal responsable de cette altération hydrothermale et de la minéralisation est peu salé et d’origine superficielle. Le fluide hydrothermal est de plus sous-saturé en silice mais sursaturé en Na, U et Zr.The Proterozoic uranium ore deposits of Kurupung batholith (2041 ± 29 Ma, North-West of Guyana) and of Kirovograd - Novoukrainsk (granite dated at 2047 ± 19 Ma, Ukraine) are two occurrences where the mineralization (occurring as uraninite, pitchblende, U-Ti oxide) is associated to sodium metasomatism. These occurrences and also the similar mineralizations of South Morocco and of Lagoa Real (Brazil) seem to belong to a major Paleoproterozoic metallogenic event characterized in this study. The uranium ore deposit of Espinharas (Brazil) is also associated to a sodium mineralization and presents a uranium mineralization mainly occurring as coffinite crystals, uranium oxide and uranothorite. This hydrothermal alteration has different stages: (i) albitization with an isomorphic replacement of orthoclase and plagioclase by albite, following by a complete dissolution of the quartz; (ii) crystallization of euhedral albite in cavities left by quartz leaching, following by (iii) the crystallization of calcic minerals (calcite, epidote, pyroxene), uranium minerals (uraninite and/or pitchblende and/or brannerite and/or U-Ti oxide according the ore deposits), hydrothermal zircons, chlorite, and sometimes secondary quartz. The isotopic study (delta18Oalbite between 2.2 and 2.9 ‰ for Ukraine albitites; delta18Oalbite and delta18Ocalcite are between 2.8 and 5.3 ‰ for Guyana albitites) and the microthermometric study (Th > 350°C) have permit to show that the hydrothermal fluid responsible of this hydrothermal alteration and the mineralization is a surface derived fluid with a less salinity. The hydrothermal fluid is silica under-saturated but over-saturated in Na, U and Zr
Characterization of Archean uranium sources : genetic mechanisms of the oldest uranium deposits (3.0 to 2.2 Ga) and of Paleoproterozoic uraniferous pre-concentrations
No full textLes plus anciens gisements d’uranium connus sur Terre sont les gisements de type paléo-placer hôtes de conglomérats à cailloux de quartz d’âge compris entre 3,09 et 2,2 Ga. Ces gisements représentent les reliques de l’ancienne croûte continentale archéenne maintenant érodée. L’origine de leurs concentrations primaires, correspondant à des accumulations de grains détritiques d’uraninite, est toujours sujette à controverse et la nature et les processus de formation des roches sources archéennes demeurent incertains.Ce travail présente l’analyse minéralogique et géochimique détaillée des minéralisations de différents paléo-placers (Witwatersrand en Afrique du Sud, Elliot Lake au Canada et séries Jatuliennes en Russie) ainsi que de granitoïdes archéens et paléoprotérozoïques enrichis en uranium (séries granitiques calco-alcalines à potassiques du craton de Kénéma Man en Guinée, granites tardi-orogéniques du craton de Pilbara en Australie Occidentale, pegmatite peralumineuse de Tanco du Bouclier Canadien et pegmatites à uraninite du Bouclier Baltique en Finlande et Russie). L’étude comparative de ces roches uranifères échantillonnées tout autour du globe prouve à la fois i) l’existence précoce (>3,1 Ga) de granitoïdes différenciés produits par la fusion partielle d’une croûte pré-enrichie tels que des granites peralumineux ou de type S, ii) nécessairement la présence d’un mécanisme permettant de produire ce type de granites comme les zones de subduction ou de collision générées par le mouvement des plaques tectoniques, iii) l’origine magmatique des uraninites thorifères des paléo-placers, iv) la présence d’une atmosphère réductrice avant 2,2 Ga permettant la préservation des uraninites durant leur transport, v) et finalement l’augmentation de l’oxygène libre dans l’atmosphère paléo-protérozoïque à partir de 2,2 Ga provoquant la disparition des paléo-placers uranifères en faveur de l’altération et de l’oxydation des concentrations préexistantes, de la remobilisation de l’uranium et de la formation de dépôts secondairesThe oldest known uranium deposits on the Earth are the paleoplacer-type deposits hosted in quartz-pebble conglomerates from 3.09 to 2.2 Ga in age. These deposits are representative of the ancient Archean continental crust now eroded. The origin of the primary ores corresponding to accumulation of detrital uraninite is still controversy and the nature and forming processes of the Archean source rocks remain uncertain.This work provides the detail mineralogical and geochemical analysis of mineralization from different paleoplacer-type deposits (Witwatersrand in South Africa, Elliot Lake in Canada and the Jatulian series in Russia) and from Archean and Paleoproterozoic U-enriched granitoids (calco-alkaline to potassic granite series from the Kenema Man Craton in Guinea, late-orogenic granites from the Pilbara Craton in West Australia, the Tanco pegmatite from the Canadian Shield and uraninite bearing pegmatites from the Baltic Shield in Finland and Russia). The comparative study of these worldwide uraniferous rocks prove either i) the existence of highly differentiated granitoids produced by the partial melting of a pre-enriched crust as peraluminous and S-type granites in early time (>3.1 Ga), ii) obviously the presence of an effective mechanism to produce such granites as tectonic plate systems with subduction or collisional zones, iii) the magmatic origin of the thorian uraninites in paleoplacers, iv) the efficiency of a reductive atmosphere prior to 2.2 Ga permitting the preservation of uraninite during transportation, v) and finally the rise of the oxygen-free level in the paleoproterozoic atmosphere providing the disappearance of uraniferous paleoplacers in favour of weathering, oxidation of pre-existing concentrations, remobilization of uranium and formation of secondary deposit
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
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