1,720,965 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
Markov Walk Exploration of Model Spaces: Bayesian Selection of Dark Energy Models with Supernovae
Get PDFCentral to model selection is a trade-off between performing a good fit and
low model complexity: A model of higher complexity should only be favoured over
a simpler model if it provides significantly better fits. In Bayesian terms,
this can be achieved by considering the evidence ratio, enabling choices
between two competing models. We generalise this concept by constructing
Markovian random walks for exploring the entire model spaces governed by the
logarithmic evidence ratio, in analogy to the logarithmic likelihood ratio in
parameter estimation problems. The theory of Markovian model exploration has an
analytical description with partition functions, which we derive for both the
canonical and macrocanonical case. We apply our methodology to selecting a
polynomial for the dark energy equation of state function fulfilling
sensible physical priors, on the basis of data for the supernova
distance-redshift relation. We conclude by commenting on Jeffreys' scale for
Bayesian evidence ratios, choices of model priors and derived quantities like
Shannon entropies for posterior model probabilities.Comment: 12 pages, 7 figure
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
Optimising tomography for weak gravitational lensing surveys
Get PDFThe subject of this paper is optimisation of weak lensing tomography: We
carry out numerical minimisation of a measure of total statistical error as a
function of the redshifts of the tomographic bin edges by means of a
Nelder-Mead algorithm in order to optimise the sensitivity of weak lensing with
respect to different optimisation targets. Working under the assumption of a
Gaussian likelihood for the parameters of a CDM-model and using
Euclid's conservative survey specifications, we compare an equipopulated,
equidistant and optimised bin setting and find that in general the
equipopulated setting is very close to the optimal one, while an equidistant
setting is far from optimal and also suffers from the ad hoc choice of a
maximum redshift. More importantly, we find that nearly saturated information
content can be gained using already few tomographic bins. This is crucial for
photometric redshift surveys with large redshift errors. We consider a large
range of targets for the optimisation process that can be computed from the
parameter covariance (or equivalently, from the Fisher-matrix), extend these
studies to information entropy measures such as the Kullback-Leibler-divergence
and conclude that in many cases equipopulated binning yields results close to
the optimum, which we support by analytical arguments
Constructing Exact Confidence Regions on Parameter Manifolds of Non-Linear Models
Get PDFUsing the mathematical framework of information geometry, we introduce a
novel method which allows one to efficiently determine the exact shape of
simultaneous confidence regions for non-linearly parametrised models.
Furthermore, we show how pointwise confidence bands around the model
predictions can be constructed from detailed knowledge of the exact confidence
region with little additional computational effort. We exemplify our methods
using inference problems in cosmology and epidemic modelling. An open source
implementation of the developed schemes is publicly available via the
InformationGeometry.jl package for the Julia programming language.Comment: 24 page
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
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