1,720,960 research outputs found
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
Responses of transgenic poplar (Populus tremula x P. alba) overexpressing glutathione synthetase or glutathione reductase to acute ozone stress: visible injury and leaf gas exchange
No full textUntransformed hybrid poplar (Populus tremula × P. alba) and transgenic lines overexpressing glutathione synthetase (GshS) in the cytosol (200–300-fold) or glutathione reductase (GR) either in the cytosol (5-fold) or in the chloroplast (150–200-fold) were exposed to 0 (control), 100, 200 or 300 nl l−1 ozone for 3 d for 7 h d−1. Following acute ozone stress treatments, wild-type and transgenic poplar suffered from visible foliar injury consisting of dark brown necrotic lesions on the laminae. Necrotic lesions were sharply separated from photosynthetically active cells by a band of red-violet discoloured cell lines showing yellow autofluorescence by blue light, and blue autofluorescence by UV-light excitation. When plants were exposed to 100 nl l−1 ozone, leaf injury was in general negligible, but when 200 and 300 nl l−1 ozone was applied, in both untransformed poplar and transgenic lines overexpressing GshS or GR up to 60% and 80%, respectively, visible injury developed on mature leaves. The mean percentage of injured leaf area amounted to 20–30% (200 nl l−1) and 50–60% (300 nl l−1). Irrespective of transformation, young leaves of poplar trees were only slightly affected by ozone treatments. In support of these observations, net CO2 assimilation rates of mature leaves were decreased by up to 75% (300 nl l−1 ozone) in wild-type and transformed poplar, whereas net photosynthesis of young leaves remained unaffected even under severe stress conditions. Leaf conductance was significantly decreased by all ozone treatments, but was in the same range in young and mature leaves, and in wild-type and transformed poplar, pre- and post-exposure to ozone. It can therefore be assumed that the ozone doses effectively taken up into the leaf tissue were not dependent on leaf development and that the strength of the ozone stress exerted was similar in all types of poplar trees investigated in this study. From these data it is concluded that: (i) elevated foliar activities of glutathione synthetase or glutathione reductase alone are not sufficient to improve tolerance of hybrid poplar to acute ozone stress, and (ii) the sensitivity of poplar leaves to acute ozone stress is controlled by unknown factors closely related to leaf development rather than by foliar activities of glutathione synthetase and glutathione reductase, or leaf conductance
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
Responses of antioxidative systems to acute ozone stress in transgenic poplar ( Populus tremula × P. alba) over-expressing glutathione synthetase or glutathione reductase
No full textWild-type hybrid poplar (Populus tremula × P. alba) plants and transgenic lines over-expressing glutathione reductase (GR) either in the cytosol (ca. 5-fold) or in the chloroplast (150- to 200-fold) or glutathione synthetase (GSS) in the cytosol (ca. 200-fold) were exposed for 3 days to ambient air or air containing 300 nl l–1 ozone for 7 h day–1. The contents and oxidation state of antioxidants (glutathione; ascorbate), the in vitro activities of target enzymes (GR, GSS), as well as the in vitro activities of ascorbate consuming (ascorbate peroxidase, APX) and regenerating (monodehydroascorbate reductase, MDAR; dehydroascorbate reductase, DHAR) enzymes were determined in the developing 2nd and the mature 5th leaves from the apex of the plants. The changes in the activities of the target enzymes GR and GSS also affected other components of the leaves' antioxidative system. Over-expression of GR in the chloroplast enhanced total glutathione contents of the leaves 2- to 3-fold. Foliar GSSG levels were enhanced in all transgenic poplar lines compared to wild-type plants. In developing leaves of transgenic plants, over-expressing GR in the cytosol or chloroplasts, APX and DHAR activities were higher, in mature leaves similar or lower than in wild-type plants. These differences between poplar lines did not mediate different sensitivities of the leaves to acute ozone exposure (Strohm et al., J Exp Bot 50:365–374). Still, components of the antioxidative system of the leaves showed both similar or specific reactions to acute ozone exposure in different poplar lines. Irrespective of leaf age total glutathione contents increased 2- to 3-fold in ozone-exposed leaves of all poplar lines. Also GSSG contents of the leaves increased, with the exception of plants over-expressing GR in the chloroplasts. Still a highly reduced state of glutathione was maintained in wild-type (>90%) and transgenic lines (ca. 80%) irrespective of ozone exposure. Apparently, GR activity was sufficient in all lines to compensate for ozone-mediated glutathione oxidation. Foliar GR activity increased up to 100% as a consequence of ozone treatment in wild-type and transgenic plants over-expressing GR in the cytosol, but not in plants over-expressing GR in the chloroplasts. The combined increase in total glutathione contents and GR activity in response to acute ozone exposure did not prevent injury and, therefore, cannot be considered a useful mechanism of defence, but rather an indicator of ozone-mediated oxidative stress. Total ascorbate contents and the activities of ascorbate consuming (APX) or regenerating enzymes (MDAR, DHAR) were not significantly affected by acute ozone exposure in all poplar lines. Ozone exposure strongly oxidised the foliar ascorbate pool except in leaves over-expressing GR in the chloroplast. Apparently, these leaves possess an enhanced capacity for ascorbate regeneration as a consequence of the strongly enhanced chloroplast GR activity and the simultaneously increased APX activity and glutathione levels. The enhanced antioxidative capacity did not prevent ozone-mediated injury to the leaves, most likely due to different sites of primary ozone reactions. Despite higher total ascorbate contents and higher APX activities in developing than in mature leaves, these and other components of the antioxidative system analysed in this study were not responsible for the higher sensitivity to acute ozone exposure of mature compared to developing poplar leaves
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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