1,720,962 research outputs found
Short-time effects of pure and formulated herbicides on soil microbial activity and biomass
No full textThe short-time of six pure herbicides (atrazine, terbuthylazine, rimsulfuron, primisulfuron-methyl, glyphosate and gluphosinate-ammonium) with respect to the corresponding commercial formulations on microbial activity and biomass of sandy loam soil were investigated. Application rates were: agricultural rate, 20 and 200 μg a.i. g-1 soil. Application at normal agricultural rates did not lead to significant effects on soil microbial activity, whereas soil microbial activity was markedly stimulated when pure and commercial formulations of the six herbicides were applied at 20 μg a.i. g-1 soil. The addition of 200 μg a.i. g-1 soil of four pure herbicides (atrazine, terbuthylazine, rimsulfuron, primisulfuron-methjyl) led to a significant decrease of soil microbial activity. Commercial formulations characterized by a higher relative a.i. concentration (atrazine and primisulfuron-methyl) approximately determined the same decreasing effect of the pure compound, whereas herbicide formulations with a lower relative a.i. concentration (terbuthylazine and rimsulfuron) produced a significant increase in soil microbial activity
Influence of insecticidal toxins from Bacillus thuringiensis subsp. kurstaki on the degradation of glyphosate and glufosinate-ammonium in soil samples
No full textInvestigations dealing with the persistence in soil of glyphosate [N-(phosphonomethyl)glycine] (GLYP) and glufosinate-ammonium
[the ammonium salt of dl-homoalanin-4-yl(methyl)phosphinic acid] (GLUF) herbicides and of insecticidal toxins
produced by Bacillus thuringiensis subsp. kurstaki (Berliner) are largely reported in the literature. However, no information
on the influence of these insecticidal toxins on the persistence in soil of herbicides is available. Preliminary results regarding
the influence of insecticidal toxins extracted from a commercial formulation of B. thuringiensis subsp. kurstaki (Berliner)
(Btk) on the degradation of the herbicides glyphosate and glufosinate-ammonium in a loam and a sandy loam soil, under
laboratory conditions, were obtained. Soil microbial carbon (SMC) and insecticidal activity of incubated soil samples were
also estimated. In both soil types, persistence of GLYP was significantly higher with respect to GLUF. Average GLYP and
GLUF half-life was 14.4 and 8.0 days, respectively. Addition of Btk toxins lead to a significant increase of GLYP and GLUP
persistence in both soil types. More specifically, average GLYP and GLUF half-life in soil samples receiving the Btk treatment
was 24.3 and 14.2 days, respectively. In contrast to herbicide persistence in soil, Btk toxins did not influence microbial carbon
content of incubated soil samples. The insecticidal activity of Btk toxins in soil rapidly decreased during the 28-day incubation
time. Considering that degradation of GLYP and GLUF was mainly a microbial process, the absence of effects of Btk toxins
on the soil microbial carbon and the rapid decrease of insecticidal activity of Btk toxins in the soil suggest a possible effect
of the Btk toxins on other soil properties and/or mechanisms influencing herbicide degradation. The present preliminary
investigation permitted to highlight the possibility of the Btk toxins to enhance the persistence of GLYP and GLUF in soil,
under laboratory conditions. However, further studies are necessary to investigate whether or not the effects observed in this
study under artificial and controlled conditions can be extrapolated to field conditions
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
Glyphosate and glufosinate-ammonium runoff from a corn-growing area in Italy
No full textThe main objective of this experiment was to estimate field-scale runoff losses of glyphosate and glufosinate-ammonium under
natural rainfall conditions. Investigations were carried out at the Runoff Monitoring Station of the University of Bologna (Italy). Glyphosate
and glufosinate-ammonium were applied as pre-emergence herbicides on 350-m2 field plots characterized by a uniform slope of 15%. Field
plots were cultivated with corn. The persistence and sorption isotherms of the two herbicides were also determined. During the 3-year
experimental period low runoff volumes were observed. More specifically, annual runoff volumes did not exceed 4.7 mm. Glyphosate and
glufosinate-ammonium concentrations in collected runoff samples rapidly declined with time. The highest glyphosate and glufosinate-ammonium
concentrations were 16 and 24 μg L–1, respectively. These peaks were observed in a runoff event occurring 1 day after herbicide
treatment. The total maximum amount of glyphosate and glufosinate-ammonium losses were 0.031 and 0.064‰ of the applied active ingredients,
respectively. On the basis of the obtained results, both glyphosate and glufosinate-ammonium showed low potential to contaminate surface water
resources. These results were supported by their estimated short persistence and strong sorption in soil. The half-lives of glyphosate and
glufosinate-ammonium were 17.5 and 6.4 days, respectively, and their distribution coefficients (Kd) were 746.6 and 23.4 mL g–1, respectively
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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