1,720,979 research outputs found
Zinc toxicity to nitrification in soil and soilless culture can be predicted with the same biotic ligand model
No full textThe inhibitory effect of Zn on the nitrification process in ZnCl2 spiked soils (12 soils, pH range 4.8-7.5) was compared to toxic effects of Zn on the nitrification by Nitrosospira sp. in soilless solutions with varying pH (pH 6-8) and ionic composition. The nitrification was reduced by 20% at Zn solution concentrations (EC20) ranging between 7 and 1200 microM Zn in the soil pore water and between 5 and 150 microM Zn in the soilless solutions. Protective effects of H+, Ca2+, and Mg2+ against Zn2+ toxicity were observed in both systems. Zinc speciation was determined, and 60-90% of the Zn in the soils and 35-80% of the Zn in the soilless solutions was present as Zn2+. A biotic ligand model and a Freundlich-type model, incorporating the competition of Zn2+ ions with H+, Ca2+, and Mg2+ for binding on the biotic ligands, were used to model the results. The Zn2+ activities resulting in 20% reduction of the nitrification were well predicted using the same parameters for both (soil and soilless) systems, indicating that microorganisms in soil are exposed to zinc through the free zinc ion in soil pore water.Jelle Mertens, Fien Degryse, Dirk Springael, and Erik Smolder
Positive Impact of Microorganisms on the Performance of Laboratory-Scale Permeable Reactive Iron Barriers
No full textDegradation efficiencies of zerovalent iron (Fe0) containing different bacterial inocula, i.e., an iron(III)-reducing Geobacter sulfurreducens strain and/or a bacterial consortium, were compared to degradation efficiencies of noninoculated Fe0 in a laboratory-scale column experiment. Contaminant removal efficiencies and hydrogen production rates indicated an increasing reactivity in time for all inoculated iron columns, while reactivity of the noninoculated columns remained the same. The main mineral precipitates, including carbonate green rust, ferrous hydroxy carbonate, aragonite, and to a lesser extent goethite, were observed under all imposed conditions. The higher reactivity of the inoculated column material is explicable by the reduction of ferric iron species by iron(III)-reducing bacteria, resulting in the observed higher amounts of highly reactive carbonate green rust. However, contributions of other bacteria could not be excluded. Although different groups of hydrogen-consuming bacteria were detected in the columns, no indication was found that hydrogen consumption was sufficiently high to affect reactivity or permeability of the iron matrix, as the abiotic generation of H2 was substantially exceeding its potential consumption
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
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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