1,721,008 research outputs found
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 evolution of phenotypic divergence in Icelandic Arctic charr (Salvelinus alpinus)
No full textThe process of ecological speciation involves the divergence single populations into distinct species through ecologically based divergent selection. I studied the interacting developmental, genetic, and ecological mechanisms that underlie ecological speciation in populations of Icelandic Arctic charr (Salvelinus alpinus) that vary in phenotypic divergence. Arctic charr diverged into benthic and pelagic resource-based morphs after recolonization of post-glacial lakes within the last 10,000 years from a single glacial refugium. First, I assessed the role of allometric covariation between body shape and size as a source of developmental bias. I found evidence for a common pattern of phenotypic divergence across a benthic-pelagic ecological axis, which is strongly shaped by allometric effects that may facilitate rapid evolutionary responses to selection. Second, I assessed whether the requirements for adaptive divergence as the result of ecological opportunity by testing for relationships among body shape and size, resource use, and gene flow. Significant relationships between resource use and body shape and size are consistent with the existence of performance trade-offs between benthic and pelagic environments. Benthic and pelagic morphs across populations showed similar differences in resource use likely arising from a common utilization of niche space. Resource use predicted benthic and pelagic ancestry suggesting a causal link between divergence in resource use and reductions in gene flow between morphs. Lastly, I investigated the genomic consequences of adaptive divergence between sympatric morphs and reconstructed the divergence history of populations to interpret the causes of genomic patterns. Models of sympatric divergence with continuous gene flow and allopatric divergence followed by secondary contact were both supported indicating that the evolutionary history of this species is more complex than originally thought. Phenotypic and ecological variation was associated with genomic differentiation between sympatric morphs and the formation of many narrow genomic regions of differentiation, which are related to both phenotypic and ecological variation in divergent populations. This suggests that divergent selection has resulted in the genomic differentiation of sympatric morphs. Overall, my study suggests that adaptive divergence in response to environmental heterogeneity promotes parallel phenotypic specialization on resources which may lead to genomic differentiation and ultimately ecological speciation with gene flow
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
Body size and reproductive success in Atlantic cod, Gadus morhua L.
No full textIn fish, reproductive competition among males may take two forms: (1) monopolization of females through courtship or aggression towards other males and (2) sperm competition among spermatozoa from several males to fertilize eggs from one female. This thesis tests whether body size is associated with male and female reproductive success in Atlantic cod, 'Gadus morhua'. Both forms of competition exist in Atlantic cod. The significance of body size in male reproductive success should depend on which form of competition is the prevalent way in which males gain access to eggs. The effect of sire size on the quality of semen was assessed by sperm competition experiments. Pre-mixed semen from pairs of genetically marked males was used to fertilize eggs from one female. Fertilization success was not affected by male body size. Male condition factor (K) and spermatocrit were positively associated with fertilization success. Spermatocrit was a linear function of spermatozoa density. Spermatocrit varied among males and increased during the spawning season. Relative fertilization success of males varied with different females, suggesting female choice at the gamete level. A mate competition experiment tested the association between male reproductive success and body size. Pairs of males, differing in body size, and genotype at marker loci, spawned with single females in tanks during one reproductive season. Most egg batches were fertilized by both males and the proportion of larvae sired by each male varied significantly among batches within tanks. Small males were more successful with small females, but no association between male size and success existed with large females. Male reproductive success (estimated number of larvae sired) was not associated with body size, K, or reproductive allotment (body weight lost during spawning), and was marginally associated with male relative activity. Female reproductive success was best predicted by reproductive allotment, which was correlated with female size. Fecundity was correlated with K and body size, and K was associated with hatching success. Neither female size nor K affected larval longevity without food. Egg size decreased during the spawning season and was correlated with larval size at hatching, which in turn was correlated with larval longevity
Evolutionary significance of genomic and morphological variation in Icelandic Arctic charr (Salvelinus alpinus)
No full textI examined the genetic architecture and evolutionary significance of the considerable morphological and life history variation in Arctic charr (Salvelinus alpinus) from natural and cultured populations in Iceland. I found that the sex determining locus in Icelandic Arctic charr is located on a different linkage group relative to the majority of the Atlantic lineage Arctic charr, including populations from the Fraser River in Labrador Canada and Swedish and Norwegian strains. In addition, there may be a possible conservation of a sex linkage arrangement in Icelandic Arctic charr and Atlantic salmon. These observations suggest that the differentiation of the sex determination chromosome in salmonids is still in the early stages. I then tested hypotheses regarding the genetic architecture of wild and cultured populations of Icelandic Arctic charr identifying the number and effect size of quantitative trait loci (QTL) and their conservation within and across salmonid species. QTL with genome-wide significance for body size, condition factor and age of maturation in cultured fish from the Icelandic breeding program were detected on multiple linkage groups. Comparisons with a North American cultured strain of Arctic charr and North American populations of Atlantic salmon and rainbow trout revealed some conservation in QTL. Additionally, I compared the genetic architecture of fork lengths in juvenile wild and cultured populations and found moderate conservation of genomic regions among Icelandic populations. I compared linear measurements taken on the cleared and stained heads of benthic and limnetic morphs from two lake populations expressing varying degrees of divergence. I found high genetic variation for craniofacial morphology in all morphs with no significant difference of plasticity levels between them. However, stronger family effects and weaker morph effects in the less derived lake population suggest higher genetic variation for craniofacial traits compared to the more derived system. Overall QTL (suggestive and significant) number and effect size was similar but the morphs hypothesized to be more derived within each lake had about half the number of significant QTL (p<0.01) compared to their sympatric counterpart, suggesting fixation of alleles through canalization
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