1,720,959 research outputs found
Textural influence on quantity and quality of different organic fractions in semiarid pampa soils
No full textSoil organic matter dynamics and quality during a wheat-clover rotation in a semiarid haplustoll
No full textSeveral studies have reported modifications in soil chemical and physical parameters under rotations with legume inclusion. This modification had the potential of improving soil fertility and grain production. The objective of this research was to evaluate changes in the distribution and quality of soil organic fractions during a 3 year wheat (Triticum aestivum) - 3 year red clover (Trifolium pratense) rotation. Soil samples at 0 - 0.15 m depth were taken in five of the six year rotation. Organic fractions, physically (particulate organic carbon, COP) and chemically (humic and fulvic acids, AH and AF, respectively) separated were determined and chemically and spectrometrically characterised. The quantity and distribution of the organic fractions were different along the rotation. The more labile soil organic matter fractions, COP and AF, were higher during legume phase and diminished during wheat phase. This decrease of labile relative to recalcitrant organic matter resulted in significative differences in COP:total organic carbon (COT) and AH:AF ratios between wheat and clover phase. The COP:COT ratios were lower than 19 under wheat and higher than 21 under clover. The AH presented higher nitrogen and lower sulphur contents during clover phase, while the opposite was observed during wheat phase. This compositional changes were clearly reflected by the N:S and C:S atomic ratios. Total acidity in AH was slightly increased during the legume phase, as a consequence of the significative increase in -OH phenolic groups. Infrared and fluorescence spectra of the AH from soils under wheat and clover were similar among them, probably due to the short rotation period that produce only minor changes in the AH molecular structure. Legume inclusion in the rotation increased labile organic matter fractions and modified the composition of the recalcitrant ones. Both changes would improve soil fertility and grain production
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
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