1,720,976 research outputs found
EFFECTS OF REGIONAL AIR-POLLUTION ON CROPS IN ITALY
No full textThe paper presents a synthesis of results from different studies on effects of air pollution on crops in two regions of northern (Po Plain) and central (Tuscany) Italy. The methodologies used were: (1) biological monitoring of ozone with indicator plants; (2) ambient air pollution exclusion experiments with open-top chambers; (3) controlled fumigation with sulphur dioxide in greenhouse chambers. The results so far obtained indicate that: (1) photochemical air pollution is widespread at a regional level in northern and central Italy at levels above the thresholds for phytotoxicity; (2) ambient oxidant pollution is probably causing significant biological effects and yield losses to various crop species in the Po Plain (these effects are in some cases coupled to the typical injury symptoms caused by ozone-brown stipples or foliar flecks). In contrast, sulphur dioxide fumigation only affects plant growth and physiology at levels above those usually experienced at rural sites. It can be concluded that O3 seems to be the most important phytotoxic gas at a regional level in northern and central Italy, and that the impact of this pollutant on crops is worthy of further investigation
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
ON THE EFFECTS OF EXPOSURE TO REALISTIC SULFUR-DIOXIDE LEVELS ON 6 HOST PATHOGEN COMBINATIONS
No full textThe effects of long-term exposure to a gradient of realistic concentrations of sulfur dioxide (up to 135 ppb) on six host/pathogen combinations were investigated under experimental conditions. No visible symptoms of injury were induced by the treatments on the host plants. The results obtained were quite conflicting and did not show an overall trend in the interactions. No significant effect of the pollutant gas was detected on Alternaria raphani on Raphanus sativus (radish) and Rhizoctonia solani on radish and Cucumis sativus (cucumber). A linear inhibition of parasitism was observed in Oidium tuckeri on Vitis vinifera (grape); a mixed effect (stimulation in the range 0-75 ppb, followed by an inversion of this effect in the 75-135 ppb range) was observed for the rust fungus Puccinia recondita on Triticum aestivum (wheat); a linear stimulation of Colletotrichum trifolii was assessed on Trifolium repens (clover). The mechanisms responsible for these interactions and the practical implications of these findings are briefly discussed
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
Glutathione-ascorbic acid cycle in pumpkin plants grown under polluted air in Open-top chambers
No full textEffetto della filtrazione dell'aria inquinata sul polimorfismo di enzimi detossificanti in piante di zucchino
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