1,720,983 research outputs found
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
Effect of a thin superficial layer on the estimate of hemodynamic changes in a two-layer medium by time domain NIRS
No full textIn order to study hemodynamic changes involved in muscular
metabolism by means of time domain fNIRS, we need to discriminate in the
measured signal contributions coming from different depths. Muscles are,
in fact, typically located under other tissues, e.g. skin and fat. In this paper,
we study the possibility to exploit a previously proposed method for
analyzing time-resolved fNIRS measurements in a two-layer structure with
a thin superficial layer. This method is based on the calculation of the timedependent
mean partial pathlengths. We validated it by simulating venous
and arterial arm cuff occlusions and then applied it on in vivo
measurements
Time domain functional NIRS imaging for human brain mapping
Full text linkThis review is aimed at presenting the state-of-the-art of time domain (TD) functional near-infrared spectroscopy
(fNIRS). We first introduce the physical principles, the basics of modeling and data analysis. Basic
instrumentation components (light sources, detection techniques, and delivery and collection systems) of a
TD fNIRS system are described. A survey of past, existing and next generation TD fNIRS systems used for research
and clinical studies is presented. Performance assessment of TD fNIRS systems and standardization issues
are also discussed. Main strengths and weakness of TD fNIRS are highlighted, also in comparison with
continuous wave (CW) fNIRS. Issues like quantification of the hemodynamic response, penetration depth,
depth selectivity, spatial resolution and contrast-to-noise ratio are critically examined, with the help of experimental
results performed on phantoms or in vivo. Finally we give an account on the technological developments
that would pave the way for a broader use of TD fNIRS in the neuroimaging community
Method for the discrimination of superficial and deep absorption variations by time domain fNIRS
No full textA method for the discrimination of superficial and deep absorption variations by time domain functional near infrared spectroscopy is presented. The method exploits the estimate of the photon time-dependent pathlength in different domains of the sampled medium and makes use of an approach based on time-gating of the photon distribution of time-of-flights. Validation of the method is performed in the two-layer geometry to focus on muscle and head applications. Numerical simulations varied the thickness of the upper layer, the interfiber distance, the shape of the instrument response function and the photon counts. Preliminary results from in vivo data are also shown
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
Multichannel time domain fNIRS mapping of cortical activation and superficial systemic responses during neuromuscular electrical stimulation
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