1,720,979 research outputs found
Metabolic changes in white clover clones exposed to ozone
No full textThe effects of ozone (200 ppb, 5 h) on metabolic activity of NC-S (sensitive) and NC-R (resistant) white clover clones have been investigated at
the end of fumigation and then 24 h after. NC-S exhibited foliar injury and membrane permeability was significantly increased, indicating that it was
subjected to membrane damage. No alterations were observed in NC-R. After the end of treatment, both clones decreased their CO2 fixation ability.
In NC-S, strong negative effects on photosynthetic ability were observed due mainly to mesophyllic limitation, since Ci increased significantly.
This is also suggested by an uncoupling between Gw and Amax, which came up at the end of fumigation. NC-R showed a peculiar response: after
the end of the fumigation, Ci increased. This could indicate that the limitation to photosynthetic processes can be due to non-stomatal components.
Photosynthesis was completely recovered when stress was removed. WUEi was highest in NC-R since it increased its efficiency under O3 exposure.
Thus, the absence of Gw changes after the treatment and the open stomata ability during the recovery period observed in NC-R clone may be the
strategy used to restore Amax to control values and stimulate protective mechanisms. In ozonated NC-S, the significant increase of the minimal
fluorescence and the concomitant decrease in the maximal fluorescence have determined the reduction of photochemical efficiency of PSII. This
result is a reliable sign of O3-induced photoinhibition. No significant differences are reported in the parameters of chlorophyll a fluorescence and
in quenching components of NC-R in response to O3. During the recovery period, a slight increase was observed in chlorophylls a and b and
carotenoid contents of NC-S. The exposure induced the activation of the phenylpropanoid pathway, which was in agreement with PAL activity
measured, but in NC-S a strong increase in these compounds was observed, leading us to suppose that they were not used as antioxidants and/or
as substrates of phenol-consuming enzymes such as peroxidase isoforms, phenolases and polyphenoloxidase
Acute exposure of the aquatic macrophyte Callitriche obtusangula to the herbicide oxadiazon: The protective role of N-acetylcysteine
No full textIn this study we investigated the acute exposure of the aquatic macrophyte Callitriche obtusangula to the herbicide oxadiazon (Ronstar®). The toxic effects on C. obtusangula were evaluated, 24 h after exposure, by assessing visible necrotic leaf lesions and, 12 h after exposure, via analyses of dead cells and hydrogen peroxide (H2O2) deposits localized by histocytochemical analysis with Trypan blue and 3,3′-diaminobenzidine (DAB), respectively. As a result, we found that 0.1275 μg L-1 a.i. (active ingredient) oxadiazon was the maximum concentration that produced no observable adverse effects (NOAEC) both at leaf and tissue levels, at any considered exposure time. Additionally, we assayed the protective effect of pre-treatment with 0.25 mM N-acetylcysteine (NAC), a cysteine donor, on the damage caused by the toxic herbicidal dose of 6.37 μg L-1 a.i to C. obtusangula, correlating the NAC observed protection to the direct H2O2-scavenging and to the enhancement of glutathione parameters. NAC-treated plants showed a fourfold increase in the GSH (reduced glutathione) + GSSG (oxidised glutathione) content (149.2 nmol g-1 FW) compared to controls (36.1 nmol g-1 FW); in the NAC + oxadiazon treatments, the GSH + GSSG content was more than fivefold higher (202.1 nmol g-1 FW). GSH showed a similar trend in NAC and NAC + oxadiazon treatments, being six- (130.0 nmol g-1 FW) and eightfold (185.0 nmol g-1 FW) higher, respectively, compared to controls (20.7 nmol g-1 FW). Accordingly, the GSH/GSSG ratio in NAC- and NAC + oxadiazon-treated plants was significantly increased compared to controls, indicating alleviation of oxidative stress. © 2008 Elsevier Ltd. All rights reserved
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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