1,721,750 research outputs found
Nickel‐Catalyzed C−H Chalcogenation of Anilines
No full textThe C-H thiolation of aniline derivatives was accomplished with a versatile nickel(II) catalyst under ligand-free conditions. The robust nature of the nickel catalysis system was reflected by the C-H thiolation with a good functional group tolerance and an ample scope, employing anilines possessing removable directing groups. The widely applicable nickel catalyst also allowed for aniline C-H selenylations, while mechanistic studies provided strong support that the rate-determining step is the C-H activation.European Research Council under the European Community [307535
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
Animal distributions and movement behaviors in relation to resource dynamics
Full text linkAnimal movements, whether spatially constrained or spread across broad spatial scales, are often motivated by a need for resources. This thesis seeks to explore the role spatial and temporal resource dynamics may play in animal movements and population distributions.
The first chapter synthesizes existing research of animal movements and builds a conceptual framework that integrates individual-level movement behaviors. It distinguishes among (1) non-oriented movements in response to proximate stimuli, (2) oriented movements utilizing perceptual cues of distant targets, and (3) memory mechanisms that assume prior knowledge of a target's location. I outline how species' use of these mechanisms should depend on resource dynamics and lead to population-level patterns, such as sedentary ranges, migration between disjunct and predictable seasonal resource areas, or nomadism when resource distributions are unpredictable in both space and time.
The second chapter examines resource dynamics in an empirical setting, which, especially in ecosystems where changes may happen rapidly across broad spatial scales, is challenging because field measurements may be logistically infeasible. I use satellite imagery of vegetation productivity to track habitat dynamics for Mongolian gazelles in the eastern steppes of Mongolia. I show that spatiotemporal variation of gazelle habitats is extremely high, which may force gazelles to range over vast areas in search of food. This has important conservation implications because single protected areas may not provide sufficient gazelle habitats at all times and landscape level management plans are needed.
In the third chapter I develop a theoretical simulation model, that implements and combines the three different classes of movement behaviors (non-oriented, oriented, memory) and explores their efficiency under different scenarios of resource dynamics. Adapting techniques from artificial evolution and intelligence, I show how individuals evolve to rely heavily on memory if their landscape dynamics are predictable. In contrast, non-oriented movement evolves predominately in situations where landscape dynamics are unpredictable. Oriented movement proves important at smaller scales, when movement targets are distributed within perceptual ranges.
Future studies may transfer this theoretical model into empirical settings and use actual dynamic habitat models like that developed in chapter two, to reveal the underlying movement behaviors of real animals
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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