1,721,001 research outputs found
CORRELATION BETWEEN RELATIVES FOR COLORECTAL-CANCER MORTALITY IN FAMILIAL ADENOMATOUS POLYPOSIS
No full textIt has long been realized that age-specific cancer mortality in Familial Adenomatous Polyposis (FAP) was bimodal, and a theory was proposed in which the involved locus was polymorphic in the general population. After the molecular cloning of the region 5q21. it has been suggested that the phenotypic variability in FAP may be due to the interaction of two loci, one of which is polymorphic. We show that these two hypotheses lead to different predictions of the correlation between relatives for a phenotypic trait. and use colorectal cancer mortality data from the Italian Polyposes Registry to verify them. We conclude that the first of the two is more likely and suggest that the same variation that we observe among the affected subjects is present in the general population, thus causing a significant difference between individuals for colon cancer susceptibility
Phenotypic divergence in widespread plants : genetic drift, selection and plasticity
Full text linkThis thesis presents studies that describe and explain phenotypic differentiation within several alpine plant species. The key elements that are addressed are threefold: (1) effects of neutral genetic drift, natural selection and phenotypic plasticity on phenotypic differentiation; (2) effects of glacial history, geography and climate on phenotypic differentiation and adaptation; (3) genetic structure and gene flow at small spatial scale. Combining all three elements, the aim of this thesis is to understand how a plant species' evolution towards its current state is affected at different spatial scales by neutral genetic drift and historical (i.e. glaciation-related) as well as more recent (i.e. postglacial) environmental influences.
To measure phenotypic differentiation in important plant traits, common garden experiments were performed with several alpine plant species (Campanula thyrsoides, C. barbata, Geum reptans) sampled from populations across the European Alps and Jura Mountains. Phenotypic differentiation was generally mirrored by molecular differentiation into distinct phylogeographic groups, which is explained by long-term survival in isolated glacial refugia. The results therefore suggest that glacial history affected not only the species' neutral genetic structure but also its phenotype. For some traits and in some regions, such differentiation could be explained as adaptation to the regional environment. For instance, the distinct phenology in Campanula thyrsoides, showing delayed flowering in the submediterranean southeastern Alps contrasting with early flowering at higher elevation in the other regions to the west, is clearly an adaptation to season length in the respective environments. Differentiation in various other traits could not be explained as adaptations and may therefore be due to drift alone.
Postglacial adaptation was detected when correlating trait values with altitude of origin. For instance, the negative correlation of altitude with plant height in Campanula thyrsoides, achieved without compromising flower production, is probably an adaptation to harsher conditions and to increased investment in roots.
Adaptation can also occur through phenotypic plasticity. In an experiment in which Campanula thyrsoides was grown in common gardens at three different altitudes, variability in the functional trait of specific leaf area could be dissected into a constitutive genetic part and a phenotypic plastic part.
At the local scale, populations of C. thyrsoides were considerably differentiated in neutral molecular markers, which could be due to founder effects in the recent past. Experimental studies showed that seed dispersal was also limited in the landscape. Within-population genetic diversity was found to be high and probably the result of strong self-incompatibility and outcrossing in this species. In line with this, a paternity analysis showed that pollen dispersal is well-mixed within the investigated population, but a substantial amount of pollen was derived from neighbouring populations in this specific landscape, indicating ongoing mixture.
To conclude, the studies described in this thesis showed that glacial history had strong effects on phenotypic differentiation, and that part of this differentiation is due to adaptation to past as well as current conditions, whether through constitutive genetic adaptation or phenotypic plasticity - though neutral genetic drift may also have a substantial contribution to differentiation. At the local scale, the heterogeneity of the European Alps and the particular autecology of alpine species may have contributed to local differentiation
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
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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