1,721,122 research outputs found
From land to water, an overview of organic matter research in France. Proceedings of the Sainte-Maxime 2009 symposium organized by the French network on organic matter research
No full textBiogeochemistry ISI Document Delivery No.: 823MJ Times Cited: 0 Cited Reference Count: 22 Derrien, Delphine Dignac, Marie-France Dudal, Yves Springer DordrechtInternational audienc
Molecularly imprinted polymer solid-phase extraction for detection of zearalenone in cereal sample extracts
No full textThe aim of this work was to develop a method for the clean-up and preconcentration of zearalenone from corn and wheat samples employing molecularly imprinted polymer (MIP) as selective sorbent for solid-phase extraction (SPE). Cereal samples were extracted with acetonitrile/water (75:25, v/v) and the extract was diluted with water and applied to an AFFINIMIPTM ZON MIP-SPE column. The column was then washed to eliminate the interferences and zearalenone was eluted with methanol and quantified using HPLC with fluorescence detection (λexc=275/λem=450nm). The precision and accuracy of the method were satisfactory for both cereals at the different fortification levels tested and it gave recoveries between 82 and 87% (RSDr 2.5-6.2%, n=3) and 86 and 90% (RSDr 0.9-6.8%, n=3) for wheat and maize, respectively. MIP-SPE column capacity was determined to be not less than 6.6μg of zearalenone and to be at least four times higher than that of immunoaffinity column (IAC). The application of AFFINIMIPTM ZON molecularly imprinted polymer as a selective sorbent material for detection of zearalenone fulfilled the method performance criteria required by the Commission Regulation (EC) No. 401/2006, demonstrating the suitability of the technique for the control of zearalenone in cereal samples. © 2010 Elsevier B.V
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
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
Sequestration of carbon and nitrogen deriving from beech leaf litter within organo-mineral associations : a macroscopic, nanometric and molecular approach
No full textLes associations organo-minérales jouent un rôle prépondérant dans la séquestration à long terme des matières organiques des sols forestiers, mais les contributions des différents types d’association organo-minérale à la stabilisation, ainsi que les processus microbiens qui en sont responsables, restent mal connus. Pour y remédier, des techniques de traçage isotopique ont été combinées à la séparation densitométrique séquentielle des associations organo-minérales. Ces dernières ont été investiguées in et ex situ, à différentes échelles spatiales (macroscopique, submicrométrique et moléculaire) et temporelles (de 8 heures à 12 ans).Quatre types d’association organo-minérale ont été distingués : les débris végétaux associés à quelques rares minéraux, les agrégats végétaux, les agrégats microbiens et les grains minéraux. Le traçage isotopique du carbone et de l’azote dérivés des litières de feuilles a mis en évidence, à l’échelle de la décennie, des transferts entre les différentes associations organo-minérales. Tous deux entrent dans le sol sous forme de fragments végétaux, puis migrent progressivement vers les agrégats végétaux et microbiens. Les agrégats apparaissent pertinents pour la stabilisation du carbone et de l’azote à l’échelle décennale. Une petite fraction du carbone et de l’azote apparaît rapidement stabilisée dans les grains minéraux denses. Nos observations du devenir du 15N indiquent que l’activité des microorganismes du sol est responsable de ces transferts. Les fragments de feuilles colonisés par les microorganismes sont progressivement incorporés dans les agrégats végétaux. A mesure que la décomposition se poursuit, les agrégats végétaux se disloquent pour former des agrégats plus stables, plus pauvres en matières organiques, plus enrichis en produits microbiens et plus compacts : les agrégats microbiens. La stabilisation microbienne a été étudiée aux échelles macroscopique, submicrométrique et moléculaire, principalement par NanoSIMS et LC-IRMS. Elle opère (i) directement par immobilisation dans les cellules microbiennes et (ii) indirectement via une abondante production de métabolites extracellulaires. La calibration des C/N obtenus par NanoSIMS a permis de déterminer qu’ils sont stabilisés dans les associations organo-minérales sans contrôle apparent de la chimie des matières organiques. L’incorporation du 13C dans les sucres aminés, biomarqueurs des biomasses bactériennes et fongiques, indique que les microorganismes vivants croissent où la ressource se trouve. Ils s’accumulent dans les agrégats microbiens via les processus de transfert précédemment évoqués. Ce travail souligne l’importance des agrégats pour la séquestration du carbone et de l’azote dérivés des litières à l’échelle de la décennie. Il met également en évidence le rôle des microorganismes dans les transferts et la stabilisation du carbone et de l’azote dérivés des feuilles au sein d’associations organo-minérales.Organo-mineral associations play a key role in the long-term sequestration of organic matter in forest soils. However, knowledge about the contribution of the different types of organo-mineral associations and the microbial processes involved in soil organic matter stabilisation is scant. To solve it, stable isotope techniques have been combined with the sequential density fractionation of organo-mineral associations. Isolated fractions were investigated in field and in lab, at different temporal (from 8 hours to 12 years) and spatial scales (macro-, submicron- and molecular scales).Four types of organo-mineral associations were distinguished: plant debris with little mineral attached, plant aggregates, microbial aggregates and mineral grains. Isotopically labeled beech leaf litters were tracked at a decadal time-scale to reveal transfers in between organo-mineral associations. Both litter-derived carbon and nitrogen entered the soil as plant fragments to progressively pass through plant and microbial aggregates. Aggregates appeared particularly meaningful for the stabilisation of litter-derived carbon and nitrogen at a decadal time-scale. Little of the litter-derived carbon and nitrogen was found quickly stabilized to mineral grains. Microbial activities appeared as a major controlling factor for the evolvement of organo-mineral associations, responsive for the transfers of litter-derived carbon and nitrogen. Indeed, plant debris colonized by microorganisms are progressively trapped into plant aggregates. As decomposition proceeds, plant aggregates disrupt into denser microbial aggregates. These aggregates are loaded with lesser organic matter, but enriched in stable microbial materials.Stabilisation by soil microorganisms has been studied at the macro-, submicronand molecular- scales, using mostly NanoSIMS and LC-IRMS. Microbial stabilization operated (i) directly through immobilization in microbial cells and, (ii) indirectly through large production of extracellular microbial products. By calibrating the NanoSIMS for accurate C/N ratios, extracellular microbial products have been shown to be stabilized onto organo-mineral associations without apparent control of the mineral-attached organic matter chemistry. The incorporation of 13C tracers into amino sugars, biomarkers of bacterial and fungal biomasses, revealed that living microorganisms grow where the resource is, but accumulate in microbial aggregates. Microbial biomasses moved from plant debris to microbial aggregates, likely along with the transfers of decaying litter residues as described above.This work points aggregates as meaningful organo-mineral associations for the sequestration of litter-derived carbon and nitrogen at the decadal time-scale. It also revealed the role of microorganisms in the transfers and stabilization of litterderived carbon and nitrogen within organo-mineral associations
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