1,720,957 research outputs found
Organic matter turnover in forest and arable land
Get PDFDecomposition is crucial in the circulation of global C as well as that of other elements like heavy metals. The aims of this work were to investigate and model how temperature (-4, 0.3, 5, 15, 25 and fluctuating -4/5°C) and moisture (four levels between wilting point and 100% WHC) influence the decomposition rate in a heavy clay soil incubated in the laboratory. Concentrations of Cd, Zn, Mn, Cu and Pb in spruce needles incubated in litter-bags for 6-8 years in five spruce stands were also measured and their effects on decomposition rates discussed. Decomposition rate increased significantly with increasing temperature and moisture. The decomposition rate was twice as high in the topsoil as in the subsoil samples. Temperature fluctuations did not increase decomposition rate compared with samples at constant +5°C. A two-component first-order model was superior to a single-component model to describe decomposition. Quadratic temperature and moisture response functions were used. The calculated minimum temperature (Tmin) for decomposition was -0.83°C and Q10 increased from 2.2 at 25°C to 12.7 at 0.3°C. When analysing decomposition data compiled from the literature, the two-component model was again more accurate than the single-component. The goodness of fit did not differ between the temperature response models tested, but was affected by the reference temperature. Between 5 and 35°C, a Q10-value of 2 was found to be adequate. Concentrations of Cd, Zn, Cu and Pb increased, while concentrations of Mn generally decreased during spruce needle decomposition. Concentrations considered toxic to micro-organisms were not observed. Total amounts of Cd, Zn, and Mn decreased by at least 15, 24 and 43% while total amounts of Cu and Pb increased by over 40 and 230% respectively, before they became more constant or started to decrease. A PCA indicated that dynamics of total amounts were more similar between adjacent sites than between more distant sites. The studies indicate that there is a need for more research, especially at low temperatures where decomposition rate is low. The paucity of high-precision measurements of decomposition below 5°C makes it difficult to draw conclusions about the temperature responses below this temperature. Concerning heavy metals, after about 8 years of decomposition in the field, between 20 and 40% of the litter still remained. We therefore lack a complete picture of heavy metal dynamics during the latter parts of the decomposition period
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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