1,720,977 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
Frequency-resolved dynamic functional connectivity and scale-invariant connectivity-state behavior
No full textInvestigating temporal variability of functional connectivity is an emerging field in connectomics. Entering dynamic functional connectivity by applying sliding window techniques on resting-state fMRI (rs-fMRI) time courses emerged from this topic. We introduce frequency-resolved dynamic functional connectivity (frdFC) by means of multivariate empirical mode decomposition (MEMD) followed up by filter-bank investigations. We develop our method on the most canonical form by applying a sliding window approach to the intrinsic mode functions (IMFs) resulting from MEMD. We explore two modifications: uniform-amplitude frequency scales by normalizing the IMFs by their instantaneous amplitude and cumulative scales. By exploiting the well established concept of scale-invariance in resting-state parameters, we compare our frdFC approaches. In general, we find that MEMD is capable of generating time courses to perform frdFC and we discover that the structure of connectivity-states is robust over frequency scales and even becomes more evident with decreasing frequency. This scale-stability varies with the number of extracted clusters when applying k-means. We find a scale-stability drop-off from k = 4 to k = 5 extracted connectivity-states, which is corroborated by null-models, simulations, theoretical considerations, filter-banks, and scale-adjusted windows. Our filter-bank studies show that filter design is more delicate in the rs-fMRI than in the simulated case. Besides offering a baseline for further frdFC research, we suggest and demonstrate the use of scale-stability as a quality criterion for connectivity-state and model selection. We present first evidence showing that scale-invariance plays an important role in connectivity-state considerations. A data repository of our frequency-resolved time-series is provided
Frequency-resolved dynamic functional connectivity and scale stability of connectivity-states
Get PDFIn one part of my PhD thesis, I have investigated an extension of dFC to a frequency-resolved version of it by applying a sliding window approach on time courses from different frequency scales. The method of choice for the frequency decomposition has been MEMD applied on time-series resulting
from a gICA of rs-fMRI data. Frequency scales have been defined by the resulting
narrowband IMFs. Those frequency-resolved time courses have been
segmented by using a box-car function slid over the whole time span with a
step width of one TR. For each of those windows and within each frequency
scale, correlation matrices have been calculated by cross-correlating the time
course segments. This has resulted in sets of correlation matrices for each
rs-fMRI session and scale. In a next step, on the correlation matrices from
all sessions on each scale a k-means clustering procedure has been applied.
This has resulted in frequency-resolved connectivity-states, which show
scale-stable behavior. I find a significant change of scale stability of connectivity-
states from k = 4 to k = 5 extracted centroids. To discard findings by
chance, I have investigated scale stability on shuffled and phase randomized
null-data finding an opposite trend to the empirical results. Additionally, I
have conducted post hoc filter bank investigations with a varying number of
frequency scales confirming my results. In a next step, I have used simulated
data traversing different numbers of predefined artificial connectivity-states.
Investigating scale stability of this simulated data reveals the potential of my
approach to detect data inherent cluster structure in a more objective way
than commonly used measures. Furthermore, simulations of k_inh = 4 connectivity-
states have confirmed the hypothesis of k_inh = 4 data inherent
states in the rs-fMRI case. The behavior of my introduced scale stability measure
is also supported by theoretical considerations. Since all those studies
have been conducted using windows with a constant size over frequency
scales, adaptation of window size on the varying frequency over scales is
also investigated. Eventually, the course of this work has culminated in the
development of a sensitive and potentially objective method for detecting
data inherent cluster structures of specific types of data.
The other part of my thesis has dealt with the development of ideas for
a proposal directed to the German science foundation. I have extended the recently emerging field
of simulating Ising-like systems on static functional and structural connectomes
as backbones to a dynamic version of it. I have proposed to use the
dynamic connectome resulting from dFC analysis as a time varying back-
bone introducing a time dependency to the used Ising-like systems. I have
suggested to do this in a quasistatic, dynamic, and frequency-resolved way.
Additionally, I have proposed to combine different modalities in Ising-like
systems employing an external magnetic field term. My ideas open up a way
to investigate artificially introduced damages to the used connectomes. The
dynamics of those damaged systems could then be compared to healthy ones
and also to real lesioned cortices. Since it is not clear from literature what
Ising-like system is to be preferred, I have proposed a variation of the Ising model
with a variable extent of the used neighborhood. By exploiting recent literature
findings of spreading dynamics on the human connectome, I have suggested
a way of defining variable neighborhoods. Literature findings on criticality
in rs-fMRI data yield a way of model selection for the neighborhood of the
introduced Ising-like system
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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