1,720,959 research outputs found
Estimation of hydraulic conductivity and water table map in a large‐scale laboratory model by means of the self‐potential method
No full textThe goal of this paper is to estimate the position of the water table and hydraulic conductivity of a homogeneous porous medium by means of the self‐potential method. The hydrogeophysical experiments were carried out at the Hydrogeosite Laboratory of the Istituto di Metodologie per l’Analisi Ambientale, Consiglio Nazionale delle Ricerche (Marsico Nuovo, Italy); the laboratory is a large‐scale model sized 10 × 7 × 3 m3 that is filled with a homogeneous medium made up of quartz‐rich sand with a medium‐high hydraulic conductivity in the order of 10−5 m s−1. Self‐potential signals generated by the groundwater flow, during a pumping test, were measured on the ground surface, on both the pumping and the recovery phases. A novel methodology to estimate the hydraulic conductivity from self‐potential measurements is proposed. Hydraulic conductivity very close to that calculated from hydraulic data, by means of Neuman‐type curves, has been obtained by solving the electrical flow equation through a linear least squares method. Moreover, a kriging with external drift geostatistical methodology has been proposed to estimate the hydraulic head distribution. The advantages given by this geostatistical method are that (1) hydraulic head distribution can be estimated without any previous electrokinetic coupling coefficient calculation and (2) the method is valid for either linear or nonlinear relationships between self‐potential and hydraulic head gradients. An original finding of this work is that the relationship between self‐potential signals and drawdown, around a pumping well, is not always linear: linearity applies only when the groundwater velocity is low, but high nonlinearity occurs when hydraulic head gradient rises up. Kriging with the external drift method could be used for the inversion of the hydraulic conductivity distribution, in a real heterogeneous aquifer, by means of an appropriate conditioning technique
Estimation of hydraulic conductivity in a large scale laboratory model by means of the self-potential method
No full textEstimation of hydraulic conductivity in a large scale laboratory model by means of the self-potential metho
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
Low pressure plasma functionalized cellulose fiber for the remediation of petroleum hydrocarbons polluted water
Full text linkThis work reports the first example of effective purification, at laboratory level, of water polluted by petroleum
hydrocarbons, by means of low pressure plasma fluorine grafted cellulose fiber extracted from Spanish Broom.
In order to improve the affinity of the cellulosic surface towards water dispersed hydrocarbons, its original
hydrophilic character was turned to super-hydrophobic, by a fluorine functionalization.
Batch experiments were performed with the aim of studying kinetic and thermodynamic aspects of the adsorption
process, as a function of the initial total hydrocarbon load and of the adsorbent amount. The kinetics
data showed that the fiber removal efficiency ranged between 80–90% after one minute of contact time, in
dependence of the initial hydrocarbon/fiber weight ratio (20–240 mg/g). A maximum adsorption capacity larger
than 270 mg/g was estimated by fitting the adsorption isotherm measurements with the Langmuir model. It
turned out that the functionalized fiber is capable to perform a significant hydrocarbons removal action if
compared to other cellulosic materials reported in the literature.
Finally, the efficiency of the plasma modified cellulose fiber, after iterative re-uses, was studied
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
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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