1,720,964 research outputs found
Genome-edited tree crops: mind the socioeconomic implementation gap
Get PDFThe discussion about CRISPR/Cas genome editing is focused mostly on technical aspects to improve productivity and climate resilience in major tree crops such as cocoa, coffee, and citrus. We suggest a solution to the largely ignored socioeconomic impacts for farmers, when new genome-edited varieties are introduced from the laboratory to the field
Cacao pod yield as a function of pollination, plantation management and landscape context in Western Ghana
Get PDFTheobroma cacao (cacao) is an important commodity that supports the livelihood of Ghanaian smallholder farmers and makes a major contribution to the gross domestic product of Ghana. Unfortunately, cacao production impacts the environment through unsustainable expansion of farmlands into forest land with potential consequences for biodiversity conservation. The underlying motivation for expanding farmland is to increase cacao production. This thesis argues that increasing on-farm productivity by narrowing the existing cacao yield gap can reduce the environmental impact of cacao production in Ghana. The thesis supports this claim in three papers. Paper one identifies an existing yield gap in cacao and explores the potential avenues to effectively narrow the yield gap. The biotic, abiotic and management factors that impact cacao yield are identified, and it is suggested that the current yield gap is more related to tree physiology and pollination limitation. The second paper of the thesis expands on paper one to test whether physiological factors or pollination limitation has the greater impact on cacao yield in the study area. Using empirical data from eight plantations, paper two shows evidence of pollination limitation in the study area. Open pollination is estimated to achieve 43% yield, indicating a 56% pollination limited yield gap at peak growing season in the study area. The paper also identifies the abiotic and landscape factors that drive pollination limitation in the study area. To better understand the pollination biology of cacao, with the goal to address open pollination deficit, paper three evaluates the diversity and abundance of cacao flower visitors. Twelve taxonomic groups of flower visitors are identified. The factors that affect the biodiversity of flower visitors are assessed, and the functional relationships between the flower visiting arthropods are analysed. Thrips and Dipterans are identified as the most abundant cacao flower visitors, most functionally implicated in the arthropod trophic network. The mechanism of cacao pollination by thrips is described for the first time. The thesis concludes by addressing the implication of the study with recommendations to sustain the future of the cocoa sector of Ghana, and the global value-chain
Landscape genetics of the endangered Chilean tree, Gomortega keule
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
The effect of landscape heterogeneity and anthropogenic land-uses on pollination patterns for wild cherry trees in north-eastern France
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