1,720,970 research outputs found
Understanding insect foraging in complex habitats by comparing trophic levels : insights from specialist host-parasitoid-hyperparasitoid systems
Full text linkInsects typically forage in complex habitats in which their resources are surrounded by non-resources. For herbivores, pollinators, parasitoids, and higher level predators research has focused on how specific trophic levels filter and integrate information from cues in their habitat to locate resources. However, these insights frequently build specific theory per trophic level and seldom across trophic levels. Here, we synthesize advances in understanding of insect foraging behavior in complex habitats by comparing trophic levels in specialist host-parasitoid-hyperparasitoid systems. We argue that resources may become less apparent to foraging insects when they are member of higher trophic levels and hypothesize that higher trophic level organisms require a larger number of steps in their foraging decisions. We identify important knowledge gaps of information integration strategies by insects that belong to higher trophic levels.</p
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
Caught between friends and foes : plant-mediated interactions between herbivores and flower visitors
No full textUnderstanding the interplay between ecology and evolution in complex multispecies communities is a major challenge for ecologists. Most plant species are flowering plants, and to maximize their contribution to the next generation they need to deal with antagonistic herbivores while also engaging in interactions with mutualistic pollinators. Plants respond to attack by herbivores with phenotypic changes to repel or kill the attackers, and when plants are flowering, these changes extent to flower-trait expression. As a result, herbivore attack can alter interactions with pollinators and flower feeders. Knowledge on the specificity of herbivore-induced changes in flower traits, importance for the assembly of flower-visitor networks, and associated consequences for plant fitness is limited to date. The aim of this thesis project was to investigate how attack by a range of herbivore species affects plant interactions with mutualistic and antagonistic flower visitors and whether these interactions have consequences for plant fitness. I was especially interested in specificity of plant-mediated herbivore - flower-visitor interactions. The study used the Black mustard (Brassica nigra) plant and ten different herbivore species with different feeding behaviours: some choose to feed among their favourite tissues, others are highly specialized and engage in intimate and manipulative feeding relations with the plant, whereas a few take bites or sips from different plant parts. Black mustard is an annual plant species which relies on insect pollinators for reproduction. The large fragrant inflorescences contain hundreds of small yellow flowers which attract various generalist pollinators, but also specialist florivores such as pollen beetles, Meligethes spp. Chapter 2 addresses the current knowledge on flower plasticity in response to herbivory and places flower plasticity in a community context. The chapter reviews the extent to which herbivore-induced plant responses affect multiple flower traits, and the molecular mechanisms underlying floral plasticity. To understand the adaptive value of flower plasticity with contrasting differences on pairwise interactions, it is important to adopt a community perspective. Chapter 3 evaluates specificity of plant responses to different herbivore species and how these plant responses affect flower visitors and plant fitness. The results show that attack of B. nigra by a range of different herbivores influenced plant interactions with mutualistic pollinators and an antagonistic florivore, the pollen beetle Meligethes aeneus, with consequences for plant reproduction. In Chapter 4, my aim was to investigate whether herbivore - flower-visitor interactions and associated plant fitness consequences are different when timing of herbivore attack varies over plant ontogeny. My data shows that the indirect interaction web between herbivores and flower visitors is dynamic and variable over plant ontogeny, and that consequences of herbivory for plant reproductive output are strongest when plants are attacked by herbivores early in life. Chapter 5 explored the underlying mechanisms of specificity in herbivore – flower-visitor interactions. I found that flowers show extensive plasticity in response to herbivores, that herbivore-induced changes in flower traits are mostly herbivore-species specific, and have contrasting effects on pollinators. In Chapter 6, I use manipulative experiments to explore whether herbivore choice for a given feeding site determines the outcome of plant-mediated herbivore-pollinator interactions. The results show that variation in herbivore feeding site has profound impact on the outcome of herbivore-pollinator interactions. The data presented in this thesis contribute to our understanding of the complex ecological and evolutionary dynamics in multispecies communities with antagonists and mutualists, and this is discussed in Chapter 7.</p
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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