1,721,968 research outputs found
Heliothis dispersal and migration
Full text linkA few of the many species of Heliothis (Lepidoptera, Noctuidae) are important crop pests in the Old and New Worlds. Among these, H.armigera, H.zea, H.virescens and H.punctigera are the best known. The former is a particularly destructive species of a wide range of crops cultivated in Africa, the Middle East and Asia, including several staple foods and important peasant farmer cash crops. As new cultivation techniques are introduced and more extensive areas of crops are grown, often on larger irrigation and Government development schemes, it appears that this pest is becoming increasingly important. There is a strong suspicion that H.armigera populations move locally between crops grown in sequence or intercropped and that probably more extensive migratory movement occurs, as has been demonstrated in the closely related species H. zea in North America. This has considerable implications for effective control of the pest on the crops of some of the least priviledged farmers of the Developing World and in some of the poorest countries. There are recorded instances of resistance to pesticides in the species. Clearly large scale movements could have an effect on dissemination of such resistance and affect the level of control exerted by local parasite and predator populations and hence the necessity for rapid control action to combat rapid population increases of the pest on both staple food and cash crops. The ability to forecast or warn of such incidents would assist in effective timing of control operations and maximise efficiency of any insecticidal input required. This bibliography consolidates much of the scattered literature on the migratory behaviour of Heliothis spp. and will help to identify gaps in the existing knowledge of this aspect of the ecology of the genus. It will hopefully assist in focussing attention on the necessity for work on H.armigera, which is of such great importance in Developing Countries. Work on migratory movement could lead to effective action both regionally and internationally to reduce possibilities of migration of damaging numbers of moths. It will certainly assist in increasing knowledge on the bionomics of one of the most damaging agricultural pest species in the Old World and be of benefit to some of the least advantaged farmers of the tropics
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
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