1,720,965 research outputs found
High resolution isotopic ages for the early Miocene "Patagoniense" transgression in Southwest Patagonia: Stratigraphic implications
Get PDFThe classical marine Patagoniense succession at Lago Argentino, southwestern Patagonia (Argentina), known as Estancia 25 de Mayo Formation, was dated by radiometric U-Pb on zircon grains from pyroclastic rocks and 87Sr/ 86Sr ratio on calcitic oyster shells. U-Pb data yielded an age of 19.14 Ma for the lower portion of the Patagoniense succession and 18.85 Ma for the lowermost part of the overlying Santa Cruz Formation. 87Sr/ 86Sr data yielded ages ranging from 20.05 Ma at the lower part and 19.1 Ma for the upper portion of the Estancia 25 de Mayo Formation, in good agreement with respect to the U-Pb results. Our results constrain the age of these beds entirely into the early Miocene Burdigalian stage, and locally into the Superpatagoniense stage. Correlation with other Patagoniense units in Santa Cruz, especially in the westernmost parts of the Austral Basin, reveals the existence of a shallow and extended sea, and lack of correlation with global sea-level highstands suggests a local Andean tectonic overprint as the cause of the sea level rise.Fil: Cuitiño, José Ignacio. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Geología. Cátedra de Sedimentologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pimentel, Marcio M.. Universidade Federal do Rio Grande do Sul; BrasilFil: Ventura Santos, Roberto. Universidade Do Brasilia. Instituto de Geociencias; BrasilFil: Scasso, Roberto Adrian. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Geología. Cátedra de Sedimentologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Mineralogical and geochemical characterization of a rare ultramafic lamprophyre in the Tandilia belt basement, Río de la Plata Craton, Argentina
Get PDFA metre-thick ultramafic lamprophyre dyke intrudes the basement of the andilia belt at the Sierra Alta de Vela, Argentina. A petrological and geochemical study of this rock and associated small dykes indicates a predominantly calc-alkaline trend. Phlogopite KeAr dating of the ultramafic lamprophyre gave a minimum age of 1928 +/- 54 Ma as a late event of the Transamazonian Orogeny, which is well represented in the basement of the Tandilia belt. An electron microprobe study indicates the presence of phlogopite,albite, chromite and Cr-rich phenocrysts and Cr-free microphenocrysts of diopside as primary minerals. Subsequent to deformation at the contacts with the wall rock, metasomatism generated strongly zoned amphibole (edenite, pargasite, Mg-hastingite and tremolite compositions) and andradite as well as chlorite, sericite, albite,apatite and calcite. The central zone of the lamprophyre is almost undeformed and exhibits some ocellar texture. Geochemical and isotopic signatures of the lamprophyre suggest that its magma source may have previously undergone incompatible element enrichment of the mantle source, representing the original precursor magma for the calc-alkaline dyke series of the Sierra Alta de Vela.Fil: Dristas, Jorge A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Geológico del Sur; ArgentinaFil: Martinez, Juan Cruz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Geológico del Sur; ArgentinaFil: Massonne, Hans Joachim. Universität Stuttgart; AlemaniaFil: Pimentel, Marcio M.. Universidade Federal do Rio Grande do Sul; Brasi
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
The late stages of the Pampean Orogeny, Córdoba (Argentina): Evidence of postcollisional Early Cambrian slab break-off magmatism
Get PDFWidespread rhyolitic and mafic volcanism in the northern and southern sectors respectively of Eastern Sierras Pampeanas, central western Argentina, are associated with an important phase of extension and uplift linked to slab break-off on latest stages of the Pampean Orogeny. The main orogenic deformation took place between 540 and 535 Ma based on new ages available for this region. New UePb ages in zircons from the Oncan Rhyolite and new and old recalculated zircons from Los Burros Rhyodacite in the northern sector of Sierras de Cordoba, together with new U ePb ages of the southern sector, indicate that volcanic and subvolcanic rocks of both sectors are partially coeval and unconformably overlying and/or intruding the basement rocks during a period of exhumation and subsequent cooling at 530-520 Ma. These data are in agreement with previous estimates for the final uplift of the Sierras de Cordoba based on the KeAr cooling ages. The southern sector of Eastern Sierras Pampeanas may represent deeper structural levels within the crust and is characterized by the occurrence of small mafic bodies with OIBlike signature. New and reinterpreted UePb SHRIMP and TIMS ages on zircons and monazites in the metamorphic associated rocks date this episode, which is related to a rapid slab break-off event at 519- 515 Ma. This episode is also associated with the emplacement of peraluminous granitoids, and with the extension, cooling and final uplift of the rocks affected by the Pampean Orogeny all along the Eastern Sierras Pampeanas.Fil: Ramos, Victor Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Escayola, Monica Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Leal, Pablo Rodrigo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pimentel, Marcio M.. Universidade Do Brasilia. Instituto de Geociencias; BrasilFil: Santos, João O. S.. University Of Western Australia. School Of Earth And Geografic Sciences; Australi
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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