1,721,013 research outputs found
Economics of spatial coexistence of genetically modified and conventional crops: Oilseed rape in Central France
Full text linkEurope is currently struggling to implement coherent coexistence regulations on genetically modified (GM) and non-GM crops in all EU Member States. We conduct simulations with the software ArcView® on a GIS dataset of a hypothetical case of GM herbicide tolerant oilseed rape cultivation in Central France. Our findings show that rigid coexistence rules, such as large distance requirements, may impose a severe burden on GM crop production in Europe. These rules are not proportional to the farmers’ basic incentives for coexistence and hence not consistent with the objectives of the European Commission. More alarming, we show that in densely planted areas a domino-effect may occur. This effect raises coexistence costs and even adds to the non-proportionality of rigid coexistence regulations. Instead, we show that flexible measures would be preferable since they are proportional to the incentives for coexistence and, hence, less counterproductive for European agriculture.regulation, GIS modelling, domino-effect, Crop Production/Industries,
Understanding Filipino Rice Farmer Preference Heterogeneity for Varietal Trait Improvements: A Latent Class Analysis
Full text linkUsing an experimental methodology based on investment games, we examine whether smallholder rice farmers from Nueva Ecija, Philippines have heterogeneous preferences for improvements in 10 rice varietal traits. We use a latent class cluster approach to identify different segments of rice producing households and their distinct preferences for trait improvements. These clusters were characterised post hoc using household, farm, and marketing characteristics. On average, farmers invested the most in rice varietal trait improvements that offered opportunities to reduce losses caused by lodging, insects and diseases. We found four classes of farmers with distinct preferences for improvements in variety traits. The clusters were significantly different in terms of household and farm characteristics. These findings can guide breeding research in the development of varieties that have the traits farmers identified for improvement, and that will address the unique needs of distinct farmer segments.Rio Maligalig, Matty Demont, Wendy J. Umberger and Alexandra Peralt
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
Estimating Bird Damage to Rice in Africa: Evidence from the Senegal River Valley
No full textGranivorous birds, mainly the Red-billed Quelea, have subsisted on cereal crops in Africa for centuries and have caused substantial damage. There is, however, limited recent evidence on their impact. We propose an indirect method to estimate bird-inflicted crop losses by fitting a production function with a damage abatement component and pest intensity slope dummies on a panel database of rice farmers in the Senegal River Valley. This allows us to estimate both bird damage and marginal productivity of bird control at different levels of bird pressure. Annual bird damage is found to average around 13.2% of the potential rice production during the wet seasons of 2003–2007, which translates into an average annual economic loss of 4.7 billion FCFA (€7.1 million). Our results are consistent with farmers’ perceived bird-inflicted crop losses, averaging 15.2%. More alarmingly, we observe declining marginal productivities of bird control under increasing bird pressure. Farmers indicate that at high bird pressure, the efficacy of traditional bird scaring methods is inadequate, which suggests that predictive (monitoring), preventive (population control) and protective (insurance) measures against massive invasions are more urgent than improving the average efficacy of curative measures (pest control). These findings are especially relevant to farmers and policy-makers who are currently struggling to implement an ambitious food self-sufficiency programme in Senegal.sponsorship: Yann de Mey is with the Centre for Environmental Sciences, Hasselt University, Agoralaan Gebouw D, BE-3590, Diepenbeek, Belgium. Matty Demont and Mandiaye Diagne are with the Africa Rice Center (AfricaRice), B. P. 96, Saint-Louis, Senegal. E-mail: [email protected] for correspondence. Financing from the European Union is gratefully acknowledged. This research has been made possible thanks to the valuable input of our partners SAED (Societe d'Amenagement et d'Exploitation des terres du Delta et des vallees du fleuve Senegal et de la Faleme) and UJAK (Union des Jeunes Agriculteurs de Koyli-Wirnde). Yann de Mey benefitted from a travel grant from the Flemish Interuniversity Council - University Cooperation for Development (VLIR-UOS). We thank the editor and three anonymous reviewers for their constructive comments that greatly improved this manuscript. We further thank Eric Tollens (Katholieke Universiteit Leuven), Paul D. Mitchell (University of Wisconsin-Madison) and Bertrand Muller (AfricaRice) for their valuable research support. An earlier version of this article has been presented at the Africa Rice Congress 2010, Bamako, Mali, 22-26 March 2010 where it has received the Best Paper Award in the theme 'Integrated management of pests, diseases and weeds in rice-based systems'. We are grateful to the conference organisers and participants for their useful feedback. (European Union, Flemish Interuniversity Council - University Cooperation for Development (VLIR-UOS))status: Publishe
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
Food versus Cash. Development Theory and Reality in Northern Côte d’Ivoire
No full textIn the literature on the evolution of farming systems in Sub-Saharan Africa, the food versus cash debate on the competition versus complementarity between food and export crops (such as cotton) in agricultural development seems to offer contrasting views on rural development. The purpose of the present study is to revisit these schools of thought through an empirical case study in northern Côte d’Ivoire. Farming systems are distinguished through the presence of cotton and the degree of intensification and mechanization. Non-mechanized cotton systems are severely constrained by labour bottlenecks during field preparation of cotton fields due to competition with food crops and are barely able to subsist. Mechanization, as part of the cotton program, enables cotton farms to spread labour peaks and dramatically increase cropped areas. Our findings suggest that both development theories in reality coexist rather than contrast and that neither of both simultaneously applies on all farming systems.farming systems, adoption, cotton, animal traction, Côte d’Ivoire
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