1,721,013 research outputs found
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
Parasietinfecties en immunogenetische adaptatie in cichliden van het Tanganyikameer - Een eco-evolutionair perspectief op patronen en processen
No full textIn the last two decades, genetic data considerably improved our understanding of the phylogenetic history and diversity of species, but the ultimate drivers of speciation remain poorly understood. However, it became clear that evolutionary divergence has a strong ecological component. How ecological factors contribute to evolutionary divergence at historical or contemporary time scales is therefore a key question in evolutionary biology.Parasites represent a strong ecological pressure, which is predominant in all animals. Since parasites influence survival and reproduction, they can also influence adaptation, reproductive isolation and ultimately perhaps even speciation of their host. Whether or not parasites induce local immunogenetic adaptation and hence divergence of their host across landscape, depends on how parasite communities respond to environmental and biogeographic variation, and the strength of host-parasite co-evolution.In this doctoral thesis, we address questions related to parasite infection patterns and parasite driven adaptation in a cichlid radiation in Lake Tanganyika. The African Great Lake cichlids are famous because of their astonishing species-richness, and represent one of the most powerful model systems to study the genetic basis of diversification. Especially the cichlid fishes of Lake Tanganyika are genetically and morphologically very diverse. A diversity that yet has to be explained. The processes, which lead to the emergence of so many species in such an adaptive radiation, are probably manifold and due to an interaction of several extrinsic (e.g. ecological opportunities) and intrinsic factors (e.g. key innovations or genetic propensity of a taxon to diversify). Interestingly, adaptive divergence causing shifts in diet, habitat use or behaviour might directly relate to shifts in parasite infection.We chose three host species for our studies. All of them inhabit rocky outcrops in the littoral zone of Lake Tanganyika. Whereas Tropheus moorii and Variabilichromis moorii are stenotopic and philopatric species, Simochromis diagramma is more eurytopic and may disperse across various habitats. We found this dispersal behaviour to be reflected in genetic connectivity among populations. Furthermore, screening of sympatric populations of the three species for infection with metazoan ecto- and endoparasites revealed that populations face contrasting parasite communities. In S. diagramma, contrasts are weaker, probably as a consequence of homogenization of parasite communities by host dispersal. But host dispersal is only one of many factors determining the spatial structure of parasite communities. Despite these recent advances in our understanding of parasite community structure in Lake Tanganyika, we still lack information on the distribution of intermediate hosts or how parasite communities respond to environmental variation.We observed that ecological differentiation by infection with contrasting parasite communities is paralleled by adaptive immunogenetic divergence among host populations at genes of the major histocompatibility complex (MHC) in all three host species. MHC genes play a pivotal role in the recognition of antigens and are the most polymorphic genes known in jawed vertebrates. In cichlids MHC class IIB genes occur as two clusters (a and b) on two different chromosomes. We found that the loci of the more diverse of these clusters probably originated from a single ancestral gene through a birth and death process of gene evolution after the divergence of cichlids from other percomorph lineages. Some of these loci show elevated levels of polymorphism, whereas others are less variable, indicating the existence of several MHC class IIB b loci with non-classical functions.Cichlid individuals vary in respect to the number of loci within their MHC class IIB b cluster. In our studies we found that T. moorii individuals with an intermediate number of MHC loci can deal more efficiently with their fat reserves than those with few or too many loci. The reason might be that they suffer less from parasite infection or the negative consequences of T-cell selection by a high MHC diversity.At the host species level, we observed parallel parasite infection patterns and parallel immunogenetic adaptation among sympatric populations of T. moorii and S. diagramma. Shared infection patterns might be the ultimate reason for frequent MHC trans-species polymorphism among African cichlids. But detailed information on more species will be necessary to reveal general patterns in multi-host-multi-parasite infection dynamics and how this translates to immunogenetic adaptation.The water level of Lake Tanganyika fluctuates at geological time scales. Previous research suggested that populations of the rock-dwelling cichlids T. moorii and V. moorii along the Zambian shore-line of Lake Tanganyika diverge during isolation at lake level high stands and face increased levels of gene flow at low stands. In this thesis we propose that ecological divergence might be caused by contrasting parasite communities. We speculate that this ecological differentiation significantly contributed to the morphological and genetic diversity found in these two cichlid species today.status: Publishe
Additional file 3: of Delineating species along shifting shorelines: Tropheus (Teleostei, Cichlidae) from the southern subbasin of Lake Tanganyika
Full text linkAFLP-based Neighbour Joining tree of 108 southern specimens of Tropheus. Three T. duboisi specimens were used as outgroup, statistical support was estimated by performing 1000 bootstrap replicates. (PDF 8 kb
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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