1,720,992 research outputs found
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
Oxygen Propagation Fronts in Porous Media Under Evaporative Conditions at the Soil/Atmosphere Interface: Lab-Scale Experiments and Model-Based Interpretation
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Model-based interpretation of hydrogeochemistry and arsenic mobility in a low-enthalpy hydrothermal system
No full textLow-enthalpy geothermal systems are widely spread around the world. Their exploitation for geothermal energy requires an accurate knowledge of the system. Detailed hydrogeochemical characterization is of pivotal importance since geothermal systems are often associated to the occurrence of toxic gases and elements which may contaminate any connected water resources. In this study we demonstrate how increased knowledge of a low-enthalpy geothermal system (Cimino-Vico, Central Italy) can be acquired from the analysis and interpretation of major chemistry and 87Sr/86Sr of local spring waters and groundwaters. With a model-based approach, we assess the main processes governing the major ion composition and arsenic (As) mobility in the system. The occurrence of high concentration of arsenic in the groundwater of the study area is a severe problem for the inhabitants that use the resource for domestic purposes. The system's hydrogeology consists of a shallow highly permeable aquifer, composed of alkaline-potassic volcanic rocks and characterized by fresh waters, a semi-confining layer at the base of the fresh water aquifer, and a deeper thermal aquifer in Mesozoic carbonates and Triassic evaporites. Upwelling of hot waters (up to 63 °C) to the shallow aquifer is related to the presence of faults and fractures in the semi-confining layer. The major chemistry of the deep thermal waters was found to be controlled by dedolomitization, while the fresh waters chemistry is governed by the interaction with the volcanic rocks and the mixing with the upwelling CO2-rich thermal waters. The outcomes of geochemical modeling are consistent with a conceptual model positing that arsenic bound to iron-(hydr)oxides becomes mobilized in the shallow, volcanic aquifer when thermal waters ascend into such shallow aquifer, where they promote the desorption of arsenic in favor of bicarbonate
Global sensitivity analysis of mass transfer and reaction dynamics for electrokinetic transport in porous media
Full text linkElectrokinetic (EK) technologies are promising solutions for the remediation of contaminated sites, particularly in low-permeability porous media. However, their widespread adoption is hindered by the challenge of predicting the complex, coupled physico-chemical processes triggered by the application of external electric fields in the subsurface. Numerical models therefore represent essential tools to interpret system behavior. Uncertainties in experimental data, as well as in the formulation of conceptual models, still pose a challenge to develop robust predictive tools. In this context, our work addresses the impact of various sources of uncertainty on model-based predictions of EK transport in porous media. We employ Monte Carlo-based global sensitivity analyses (GSA) within both single-model (SM-GSA) and multi-model (MM-GSA). The multi-model approach relies on a theoretical framework encompassing different models capable of interpreting a set of EK transport scenarios. This allows us to address the impact of model formulation besides parametric uncertainty on mass transfer and reaction dynamics of EK transport. All candidate models in our set are based on a 2D dipole electrode configuration and each model incorporates a different combination of physico-chemical processes to explore different EK remediation scenarios dominated by electromigration or electroosmosis, for both conservative and reactive transport settings. We also investigate the influence of background electrolytes, charge interactions, reactant mobility and degradation reaction kinetics on system dynamics. To overcome the computational burden of process-based modeling and GSA implementations, we develop machine learning-based surrogate models. The latter are employed within both SM- and MM-GSA frameworks, using Sobol’ and AMAE sensitivity indices, respectively. This work provides a comprehensive quantification of how multiple sources of uncertainty impact electrokinetic transport behavior in porous media
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