1,721,103 research outputs found
Efficacy of indigenous pesticidal plants for tomato and brassica pest management in Malawi
Full text linkThe cultivated tomato, Lycopersicon esculentum, and rape (Brassica napus) are the most important horticultural vegetable crops grown in southern Africa. However, their production is highly constrained by insect pests including red spider mites Tetranychus evansi and the aphids (Brevicoryne brassicae and Myzus persicae). The results on field surveys revealed that majority of smallholder farmers have considerable knowledge about pesticidal plants and reported Tephrosia vogelii, Vernonia amygdalina, Tithonia diversifolia and Azadirachta indica as particularly important. T. vogelii was the most popular species in Zambia (60.7%) and Malawi (53.4%) while brassicas constituted 34% and 44% of all vegetables grown in Malawi and Zambia respectively. Although insect pest infestation during the field trials was low but nonetheless, significant differences were observed between pesticidal plant extracts treated plots and the control. Use of pesticidal plants resulted in significantly lower damage to vegetables. The results further revealed that pesticidal plant products as compared to untreated control decreased the incidence of red mites, aphids and diamond back moth significantly. Although synthetic insecticides were most effective against these pests, the pesticidal plant extracts examined offered valuable contribution to pest management efforts. T. diversifolia was the most effective at reducing numbers of both red spider mites and aphids followed by T. vogelii. Crude extracts applied at a concentration of 10% w/v reduced effect onthe abundance of red spider mites and aphids significantly (P<0.001) when compared to control treatment. All the plant extracts tested had some level of toxic effect at 4% w/v. Yields of tomato treated with pesticidal plants ranged from 24,414 to 38,320 Kg ha-1 compared to control plots (21,590 Kgha-1). Vegetable damage due to levels of insect pest (aphids, red mites and diamondback moth) infestation varied from 6 to 45%. T. vogelii was a promising species in field and laboratory trials and analysis of the extracts identified several rotenoids as the biologically active components. Laboratory studies showed for this first time that the rotenoids tephrosin and deguelin were toxic against red mite and aphids. However, field experimentation with T vogelii showed that compounds were not present on the leaf surface when applied on bean leaves indicating total degradation of the compounds under the sun after three days. The study has also shown that there is substantial temporal and spatial variation in the occurrence of these rotenoids, which might affect harvesting protocols. Pesticidal plant extracts can improve vegetable production for resource poor farmers at controlling vegetable pests at much reduced costs as claimed by farmers since most plant materials are found locally or can easily be cultivated
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
Rats may be disgusting, but it’s people who have made the world they thrive in
No full textPeople and rats are mutually dependent as a result of disease cycles and medical advances made possible by animal testing, among many other things. Rats are once again in the news, thanks to recent research, showing that the black death in medieval Europe may have been carried by gerbils rather than black rats
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
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