1,720,966 research outputs found
Natural Attenuation of Chlorinated Solvents at a Complex Landfill Site
No full textThe objective of this study is to evaluate natural attenuation within groundwater at a landfill site located close to the city of Turin in Italy. The contaminants of concern found in the groundwater are primarily chlorinated aliphatic hydrocarbons (CAHs): PCE, TCE, DCE and VC, and metals such as iron, nickel and manganese. In particular, the daughter chlorinated compounds DCE and VC are present at high concentrations. The collection of groundwater biogeochemical data showed that two zones with distinct geochemical environment can be identified in the groundwater at the site. In the first zone aerobic conditions are found, while the second zone is charachterized by anaerobic conditions supporting a strongly reducing environment. Therefore, combined anaerobic and aerobic microbial processes are responsible for the degradation of chlorinated ethenes in the groundwater underlying the landfill. Also the metal contamination can be related to natural processes and, in particular, the high concentrations of dissolved iron and manganese are likely to be consequence of the biological activity, triggered by the organic load present in the landfill leachate
Modeling of Redox Zonation Downgradient of Landfill Sites
No full textThe release of landfill leachate, with its load of organic material, gives rise to a succession of redox zones in the contaminated aquifer. Indigenous microbial populations can couple the oxidation of the organic compounds to the reduction of a number of electron acceptors. The sequence of TEAPs (terminal electron acceptor processes): aerobic respiration, denitrification, Mn(IV)-reduction, Fe(III)-reduction, sulfate-reduction and methanogenesis is determined by the energy yield of each redox reaction. This study presents a kinetic description of these processes using the multispecies reactive transport code RT3D. A user-defined kinetic was developed in order to take into account the principal biogeochemical processes that are likely to occur downgradient of a landfill. This model was tested on simple batch, 1D and 2D problems before applying to a field data set collected at a mixed municipal and industrial landfill site located close to the city of Turin in Italy
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
Modeling TEAPs and computing redox zonation in contaminated aquifers
No full textThe release of oxidizable organic contaminants in shallow aquifers leads to the segregation of the contaminated groundwater into different redox zones. This is due to the indigenous microbial reactions that can couple the oxidation of the organic compounds to the reduction of a number of electron acceptors naturally present in the aquifer system. The sequence of the TEAPs (Terminal Electron Acceptor Processes): aerobic respiration, denitrification, Mn(IV)-reduction, Fe(III)-reduction, sulfatereduction and methanogenesis is determined by the energy yield of each redox reaction (Chapelle et al., 1995). This study presents a kinetic model of the redox processes using the multispecies reactive transport code RT3D (Clement, 1997). A user-defined kinetic model (Kin_REDOX) was developed to account for the the principal biogeochemical reactions that are likely to follow the release of a generic organic contaminant (CH2O). Post processing programs have been developed to calculate point by point reaction rates of each TEAP and to display the computed redox zones. The model was tested using batch, one, and two dimensional problems
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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