1,720,976 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
MILD COGNITIVE IMPAIRMENT: STRUCTURAL, METABOLICAL AND NEUROPHYSIOLOGICAL EVIDENCE OF A NOVEL EEG BIOMARKER
No full textBackground: recent studies demonstrate that the alpha 3/alpha 2 power ratio correlates with cortical atrophy, regional hypoperfusion and memory impairment in subjects with mild cognitive impairment (MCI).Methods: evidences were reviewed in subjects with MCI who underwent EEG recording, Magnetic Resonance Imaging (MRI) scans and memory evaluation. Alpha3/alpha2 power ratio (alpha2 8.9–10.9 Hz range; alpha3 10.9–12.9 Hz range), cortical thickness, linear EEG coherence and memory impairment have been evaluated in a large group of 74 patients. A subset of 27 subjects within the same group underwent also Single Photon Emission Computed Tomography (SPECT) evaluation. Results: in MCI subjects with higher EEG upper/low alpha power ratio a greater temporo-parietal and hippocampal atrophy was found as well as a decrease in regional blood perfusion and memory impairment. In this group, an increase of theta oscillations is associated with a greater interhemispheric coupling between temporal areas. Conclusion: the increase of alpha3/alpha2 power ratio is a promising novel biomarker in identifying MCI subjects at risk for Alzheimer’s diseas
Neurophysiology in Alzheimer's Disease and Dementia
No full textAlzheimer's disease (AD) and dementia are the most common neurodegenerative disorder. Since the number of individuals with AD and dementia is expected to increase considerably in the near future, reliable treatment and diagnosis are critical. EEG and neurophysiological technique could be used as a cost-effective screening tool for early detection and diagnosis in the Mild Cognitive Impairment (MCI) stage. The aim in neurophysiology research is to develop signal processing methods that improve the specificity for diagnosing dementia; we wish to discover signal features that not only significantly differ in AD patients, but also allow us to reliably separate AD patients and control subjects. This approach is valuable for clinical purposes (as diagnostic tool for dementia), and it also more fundamentally contributes to a better understanding of brain dynamics of MCI patients. Finally, the development of neurophysiological biomarker could be useful in monitoring pharmacological treatments. The main focus of this special issue will be on the most recent developments and ideas in the field of EEG and neurophysiology which will enable us to extract features that improve the specificity for diagnosing AD and dementia
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
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