1,721,055 research outputs found
Synsedimentary ash rains and paleoenvironmental conditions during the deposition of the Chachil Formation (Pliensbachian) at its type locality, Neuquén Basin, Argentina
Full text linkA detailed sedimentological analysis of the so called “Chachil Limestones” at its type locality around the Mirador del Chachil area, southwestern Neuquen province, Argentina, is presented in this paper for the first time. It is based on a macro/microfacial analysis and their environmental interpretation by means on texture, fabric, bioclasts, intrabasinal and extrabasinal grain amounts, sedimentary structures, bioturbations and hydro-dynamism. Because of the recognition of different facies associations, but no pure limestones, it is more suitable to refer these sediments as the Chachil Formation. The depositional environment of this unit is interpreted to correspond to an internal platform dominated by tides, with carbonate sedimentation disturbed by repeated explosive volcanic episodes, which reduced the sedimentation space, causing retrogradation of the sedimentary system and coastal onlap. In addition, a new recalibration of the U-Pb zircon dating used for the geochronological analysis reveals a small change with regard to previous information that has been used to recalculate the data, is presented in this paper.Fil: Armella, Claudia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geocronología y Geología Isotopica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geocronología y Geología Isotópica; ArgentinaFil: Leanza, Hector Armando. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Corfu, Fernando. University of Oslo; Norueg
Clinopyroxene-Rutile phyllonites from the East Tenda Shear Zone (Alpine Corsica, France): pressure-temperature-time constraints to the Alpine reworking of Variscan Corsica
No full text""The East Tenda Shear Zone is the regional structure that marks the Alpine overthrusting of the Ligurian–. Piedmontese ocean onto the Variscan Corsica. We present the first report of a Na-pyroxene (acmite)–. rutile-bearing assemblage from a phyllonitic shear zone that occurs within the gneissic lithologies of the East. Tenda Shear Zone. Acmite hosts inclusions of Na-amphibole and titanite, and is rimmed by retrogressive. biotite. Forward modelling of the shear zone assemblages in the NCKFMASTho chemical system indicates. a cold burial–exhumation path (palaeogeothermal gradient <10 °C km−1) and a metamorphic climax with. minimum pressure of 1.2 GPa and temperatures of 350–400 °C. U–Pb thermal ionization mass spectrometry. analyses on synkinematic rutile yield a 3D array with an age of 48 ± 18 Ma (MSWD 7.3), whereas coexisting. acmite–phengite and coatings of oxides or sulphides provide an intercept at 54 ± 8 Ma (MSWD = 48).. The scatter of the arrays is considered to reflect secondary disturbances of the system and the age provided. by acmite–phengite and the coatings at 54 ± 8 Ma is considered the most reliable estimate for shear zone. formation. Implications of these new metamorphic and geochronological data are discussed in the regional. framework of the Alpine geology and integrated in the plate-tectonic scenario of the central Mediterranean."
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
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