1,720,962 research outputs found
Pesticide Fate in Different Climates
No full textPassive air samplers (PAS) using XAD-resin were deployed at a wide variety of sites around the world for four years to asses the spatial and temporal trends of legacy organochlorine pesticides (OCPs) and current use pesticides (CUPs) in the global atmosphere. Legacy OCPs are prevalent in developing countries, whereas certain CUPs dominate in North America and Europe. OCP levels are declining world wide. Concentrations from the XAD-based PAS agreed with those from polyurethane foam (PUF) disk PAS within a factor of 4 for most sites. The comparison revealed that the sampling rate of the PUF-based PAS is more dependent on wind speed, whereas that of the XAD-PAS has a higher dependence on temperature.
Analysis of PAS deployed across arid, subtropical Botswana showed that recent use has more impact on present day air concentrations than historical use. Year-long measurements by high volume air sampling in Botswana yielded higher HCB levels in winter, and higher endosulfan levels in summer. Those variations are neither related to temperature fluctuation nor seasonal hydrological events, and are therefore more likely caused by pesticide usage pattern. Very low levels of OCPs were found in the warm, dry, low organic matter soils of Botswana, including in soils from historical use areas. Such soils appear to have a low long-term storage capacity for pesticides allowing for rapid volatilization. They are thus not long-term sources of pesticides to the atmosphere. Endosulfan sulfate levels were observed to increase in tropical soils with increasing elevation. Water samples from high altitude cloud forests in Costa Rica contained very low concentrations of CUPs and it is unlikely that that those levels pose a threat to amphibians in cloud forests.
Laboratory experiments and literature analysis showed that the inert gas stripping method for the determination of air-water partitioning equilibria is susceptible to surface sorption artifacts for chemicals with a interface-air partition coefficient log (KIA/m) > -3. Using larger bubbles reduces the surface-to-volume ratio and produces accurate air-water partition coefficients for chemicals with log (KIA/m) < -1.2.Ph
Pesticide Fate in Different Climates
Get PDFPassive air samplers (PAS) using XAD-resin were deployed at a wide variety of sites around the world for four years to asses the spatial and temporal trends of legacy organochlorine pesticides (OCPs) and current use pesticides (CUPs) in the global atmosphere. Legacy OCPs are prevalent in developing countries, whereas certain CUPs dominate in North America and Europe. OCP levels are declining world wide. Concentrations from the XAD-based PAS agreed with those from polyurethane foam (PUF) disk PAS within a factor of 4 for most sites. The comparison revealed that the sampling rate of the PUF-based PAS is more dependent on wind speed, whereas that of the XAD-PAS has a higher dependence on temperature.
Analysis of PAS deployed across arid, subtropical Botswana showed that recent use has more impact on present day air concentrations than historical use. Year-long measurements by high volume air sampling in Botswana yielded higher HCB levels in winter, and higher endosulfan levels in summer. Those variations are neither related to temperature fluctuation nor seasonal hydrological events, and are therefore more likely caused by pesticide usage pattern. Very low levels of OCPs were found in the warm, dry, low organic matter soils of Botswana, including in soils from historical use areas. Such soils appear to have a low long-term storage capacity for pesticides allowing for rapid volatilization. They are thus not long-term sources of pesticides to the atmosphere. Endosulfan sulfate levels were observed to increase in tropical soils with increasing elevation. Water samples from high altitude cloud forests in Costa Rica contained very low concentrations of CUPs and it is unlikely that that those levels pose a threat to amphibians in cloud forests.
Laboratory experiments and literature analysis showed that the inert gas stripping method for the determination of air-water partitioning equilibria is susceptible to surface sorption artifacts for chemicals with a interface-air partition coefficient log (KIA/m) > -3. Using larger bubbles reduces the surface-to-volume ratio and produces accurate air-water partition coefficients for chemicals with log (KIA/m) < -1.2.Ph
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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