1,720,985 research outputs found
On the Distribution of Genetic Variation in Ecological Communities
Get PDFBiodiversity in ecological communities is structured hierarchically across spatial and temporal scales. Many open questions remain as to how this structure accumulates. For example, what are the relative contributions of dispersal versus in situ speciation? Or, how important are stochastic drift versus deterministic processes? Up to this point, these questions have been investigated by isolated disciplines (e.g. macroecology, comparative phylogeography, macroevolution) using tools and data that tend to focus on only one axis of community scale data (e.g. phylogenies, relative abundances, and/or trait information). Yet we know that there are feedbacks among processes that respond on short, medium, and long time scales (local changes of abundance, accumulation of population genetic variation, and speciation processes, respectively). Therefore, the focus of my work is: first, to develop a model of the distribution of genetic variation in ecological communities; second, to construct a multi-scale model of the accumulation of biodiversity in ecological communities that jointly models three axes of data that respond on ecological, population genetic, and phylogenetic timescales; and third, to incorporate abiotic variables with community-scale genetic data in a machine learning framework to make predictions about the distribution of genetic variation across the landscape. First, I will present a modelling approach that involves merging Hubbell\u27s neutral theory with neutral population genetic theory to construct a joint model of species abundance and genetic diversity. This model simulates joint distributions of abundance and genetic variation assuming both ecological and iv population genetic neutrality, and captures both equilibrium and non-equilibrium dynamics. These simulations can be used for a variety of applications, including estimating the shape of the abundance distribution using only a sample of community-scale genetic data. Next, I will present a model that extends the double neutral model to incorporate non-neutral processes (such as ecological interactions) and to introduce a speciation process. The goal of this work is to fully integrate abundance and trait data with phylogenies and population genetic data into a unified framework with the aim of testing community assembly models and estimating ecological parameters using observed community data. One result of this work is the finding that genetic diversity is distributed more uniformly in ecological communities than abundance. Another critical insight is that community-scale genetic data provide a record of community history on a population-genetic timescale, which can complement ecological information obtained from sampled abundance data, and deep time community history recorded in phylogenies. Finally, I will describe a machine learning framework that integrates community-scale genetic data and abiotic variables (climatic/environmental) to make predictions about genetic diversity across the landscape. I demonstrate this method using densely sampled abundances and community-scale sequence data collected from 10 decapod crustacean communities distributed throughout the Coral Triangle. The observed distributions of abundance and genetic diversity in these communities largely agree with model predictions, in that abundance distributions demonstrated higher dominance. The machine learning inference procedure identified mean annual sea surface temperature and proximity of the sampling site to deep water as key factors contributing to the shape and magnitude of community-scale genetic diversity. As community-scale genetic data becomes easier to cost-effectively obtain, this only increases the importance of hierarchical models of biodiversity accumulation that account for feedbacks across timescales to make the most accurate inference about community history from this dat
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
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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