1,720,981 research outputs found
AFC3D: A 3D graphical tool to model assimilation and fractional crystallization with and without recharge in the R environment
Get PDFAFC3D is an original graphical free software developed in the framework of the R scientific environment and dedicated to the modeling of Assimilation and Fractional Crystallization without (AFC) and with (AFC-r) recharge, facilitating the search for the solutions of the equations originally proposed by DePaolo (1981; 1985) and first solved in a graphical way by Aitcheson and Forrest (1994). The software presented here allows a graphical 3D representation of rho (mass of assimilated crust / mass of original magma) as a function of r (rate of crustal assimilation / rate of fractional crystallization) and beta (recharge rate of magma replenishment / rate of assimilation) for each element/isotope, finding a coherent set of (rho, beta, r) parameter triples in a mostly automated way. Mathematically optimized solutions are derived, which can and should then be discussed and evaluated from a geological and petrological point of view by the end user. The presented contribution presents the software and a series of models published in the literature, which are discussed as case studies of application and whose solutions are sometimes enhanced based on the results provided by the software.Fil: Guzman, Silvina Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta. Instituto de Bio y Geociencias del Noroeste Argentino; ArgentinaFil: Carniel, Roberto. Università di Udine. Dipartimento Ingegneria Civile e Architettura . Laboratorio di misure e trattamento dei segnali; Italia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Ciencias de la Tierra; Argentina. National Research University of Information Technologies, Mechanics and Optics; RusiaFil: Caffe, Pablo Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Jujuy; Argentin
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
Li content and Li and Sr isotopic compositions of deep brines from wells DRC-01 and DDD-02, and core samples (sediments, and basement rocks) from core DDD-07 - Salar de Diablillos, Argentina
No full textSr isotopes (87Sr/86Sr), Li contents and Li isotopes (δ7Li) were determined in drill core samples (sediments and rocks) and fluid (brine) samples to a depth of 250 m, obtained from Salar de Diablillos (southern Puna in north-western Argentina). For clastic sediment samples, Nd isotope compositions (143Nd/144Nd) were also determined. The Central Andes of South America hosts the largest known lithium (Li) anomalies in a restricted area, but the primary lithium sources of the salar deposits and the mobilization process of lithium are still a matter of speculation. Chemical weathering at or near the surface and leaching in hydrothermal systems of the active magmatic arc are considered as the two main mechanisms of Li extraction from the source rock. The lithium, strontium and neodimium isotope composition of typical salar deposits offer insights into the processes on how Li brine deposits in Andean evaporites are formed
Li content and Li-Sr-Nd isotope composition of salar deposits from southern Puna salars (Argentina)
No full textThe Central Andes of South America hosts the largest known lithium (Li) anomalies in a restricted area, but the primary lithium sources of the salar deposits and the mobilization process of lithium are still a matter of speculation. Chemical weathering at or near the surface and leaching in hydrothermal systems of the active magmatic arc are considered as the two main mechanisms of Li extraction from the source rock. The lithium and strontium isotope composition of typical salar deposits offer insights into the processes on how Li brine deposits in Andean evaporites are formed. To further the understanding of the different processes of Li mobilization (weathering and/or hydrothermal leaching) and accumulation that play an important role in the salars of the southern Puna in north-western Argentina, we study the Centenario, Ratones and Diablillos salars, the smallest salars that are among the world-class brine deposits in the Central Andes Li-rich salars. We use Sr isotopes (87Sr/86Sr) for source tracing and Li contents and Li isotopes (δ7Li) to constrain Li mobilization from source to deposition. Nd isotope compositions (143Nd/144Nd) were also determined in clastic sediment samples from salar to provide additional constrains to the rock sources. The studied materials include surface catchment and salar surface samples from the three studied closed basins (rocks, freshwater, brines, salts, travertine, siliciclastic sediments) and core samples (siliciclastic sediments and rocks) and fluid (brines) samples to a depth of 250 m, obtained from Salar de Diablillos (southern Puna in north-western Argentina)
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
Li, δ7Li, 87Sr/86S and 143Nd/144Nd of surface samples from Salares Diablillos, Ratones and Centenario
No full textThe Central Andes of South America hosts the largest known lithium (Li) anomalies in a restricted area, but the primary lithium sources of the salar deposits and the mobilization process of lithium are still a matter of speculation. Chemical weathering at or near the surface and leaching in hydrothermal systems of the active magmatic arc are considered as the two main mechanisms of Li extraction from the source rock. The lithium and strontium isotope composition of typical salar deposits offer insights into the processes on how Li brine deposits in Andean evaporites are formed. To further the understanding of the different processes of Li mobilisation (weathering and/or hydrothermal leaching) and accumulation that play an important role in the salars of the southern Puna in north-western Argentina, we study the Centenario, Ratones and Diablillos salars, the smallest salars that are among the world-class brine deposits in the Central Andes Li-rich salars. We use Sr isotopes (87Sr/86Sr) for source tracing and Li contents and Li isotopes (δ7Li) to constrain Li mobilization from source to deposition. Nd isotope compositions (143Nd/144Nd) were also determined in clastic sediment samples from salar to provide additional constrains to the rock sources. The studied materials include catchment and basin surface samples from the three studied closed basins
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