1,721,011 research outputs found
Ozone enhances the infection of peach leaves by the rust fungus Tranzschelia pruni-spinosae
No full textAn open-top chamber experiment was performed which highlighted the interactive effect of ozone (O-3) on the diffusion and incidence of the peach rust parasite. Such effect was linearly related to the O-3 cumulative dose received by the exposure variants, while the best fit with the daily 8-h O-3 average concentration was found to be multiplicative. Filtering ambient air reduces in a dramatic way (more than 50%) the rust severity. Stomatal conductance was neither correlated to O-3 levels nor to rust infection. The possible mechanisms involved in the above interaction are discussed herein
Stato antiossidante in talli di Xanthoria parietina esposti al cadmio o al cromo
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Coumarin inhibits the growth of carrot (Daucus carota L. cv. Saint Valery) cells in suspension culture
No full textWe used a carrot (Daucus carota L. cv. Saint Valery) cell suspension culture as a simplified model system to study the effects of the allelochemical compound coumarin (1,2 benzopyrone) on cell growth and utilisation of exogenous nitrate, ammonium and carbohydrates. Exposure to micromolar levels of coumarin caused severe inhibition of cell growth starting from the second day of culture onwards. At the same time, the presence of 50μmol/L coumarin caused accumulation of free amino acids and of ammonium in the cultured cells, and stimulated their glutamine synthetase, glutamate dehydrogenase, glucose-6-phosphate dehydrogenase and phosphoenolpyruvate carboxylase activities. Malate dehydrogenase, on the other hand, was inhibited under the same conditions. These effects were interpreted in terms of the stimulation of protein catabolism and/or interference with protein biosynthesis induced by coumarin. This could have led to a series of compensatory changes in the activities of enzymes linking nitrogen and carbon metabolism. Because coumarin seemed to abolish the exponential phase and to accelerate the onset of the stationary phase of cell growth, we hypothesise that such allelochemical compounds may act in nature as an inhibitor of the cell cycle and/or as a senescence-promoting substance
Antioxidant status in herbaceous plants growing under elevated CO2 in mini-FACE rings
No full textHere we present studies on the antioxidant status of a semi-natural grassland community, permanently
growing in mini-FACE rings under elevated concentrations of atmospheric CO2
(560μmol mol–1). In general, in leaves of Dactylis glomerata L. and Trifolium repens L., no differences
between ambient and elevated CO2 were detected as concerns protein content, activity of oxidantscavenging
enzymes (catalase, superoxide dismutase, ascorbate peroxidase and guaiacol peroxidase),
and lipid peroxidation. The activity of antioxidant-regenerating enzymes (monodehydroascorbate
reductase, dehydroascorbate reductase and glutathione disulfide reductase) and the content of
antioxidants (ascorbic acid, dehydroascorbic acid, reduced glutathione and glutathione disulfide)
showed remarkable variability between leaves from plants grown in ambient and CO2-enriched mini-
FACE rings. Thus, in general it can be concluded that the effects of elevated CO2 at environmentally
relevant concentrations on the leaf antioxidant status of a grassland community are extremely variable,
species-specific and rather limited
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
Responses of Xanthoria parietina thalli to cadmium: antioxidant status and stress protein biosynthesis
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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
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