1,720,972 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
The metabolic topography of essential blepharospasm: A focal dystonia with general implications
No full textObjective: To determine the metabolic topography of essential blepharospasm (EB). Background: EB is a cranial dystonia of unknown etiology and anatomic localization. The authors have used 18F-fluorodeoxyglucose (FDG) and PET with network analysis to identify distinctive patterns of regional metabolic abnormality associated with idiopathic torsion dystonia (ITD), as well as sleep induction during PET imaging to suppress involuntary movements, thereby reducing this potential confound in the analysis. Methods: Six patients with EB and six normal volunteers were scanned with FDG-PET. Scans were performed twice: once in wakefulness and once following sleep induction. The authors used statistical parametric mapping to compare glucose metabolism between patients with EB and control subjects in each condition. They also quantified the expression of the previously identified ITD-related metabolic networks in each subject in both conditions. Results: With active involuntary movements during wake..
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
The metabolic topography of normal aging
No full textNormal aging is associated with the degeneration of specific neural systems. We used [18F] fluorodeoxyglucose (FDG)/positron emission tomography (PET) and a statistical model of regional covariation to explore the metabolic topography of this process. We calculated global and regional metabolic rates for glucose (GMR and rCMRglc) in two groups of normal subjects studied independently on different tomographs: Group 1--130 normal subjects (62 men and 68 women; range 21-90 years); Group 2--20 normal subjects (10 men and 10 women; range 24-78 years). In each of the two groups, the Scaled Subprofile Model (SSM) was applied to rCMRglc data to identify specific age-related profiles. The validity of these profiles as aging markers was assessed by correlating the associated subject scores with chronological age in both normal populations. SSM analysis disclosed two significant topographic profiles associated with aging. The first topographic profile, extracted in an analysis of group 1 normals, was characterized by relative frontal hypometabolism associated with covariate metabolic increases in the parietooccipital association areas, basal ganglia, mid-brain, and cerebellum. Subject scores for this profile correlated significantly with age in both normal groups (R2 = 0.48 and 0.33, p < 0.0001 for groups 1 and 2, respectively). Because of clinical similarities between normal motoric aging and parkinsonism, we explored the possibility of shared elements in the metabolic topography of both processes. We performed a combined group SSM analysis of the 20 group 2 normals and 22 age-matched Parkinson's disease patients, and identified another aging-related topographic profile. This profile was characterized by relative basal ganglia hypermetabolism associated with covariate decreases in frontal premotor cortex. Subject scores for this profile also correlated significantly with age in both normal groups (group 1: R2 = 0.30, p < 0.00001; group 2: R2 = 0.59, p < 0.01). Healthy aging is associated with reproducible topographic covariation profiles associated with specific neural systems. FDG/PET may provide a useful metabolic marker of the normal aging process
The metabolic anatomy of Tourette's syndrome
No full textThe functional brain networks underlying the clinical manifestations of Gilles de la Tourette's syndrome (TS) are currently unknown. To identify these networks, we studied TS patients and normal subjects with 18F- fluorodeoxyglucose (FDG) and PET employing a statistical model of regional metabolic covariation. We studied 10 TS patients (mean age, 41.5 ± 12.7 years) who were either drug naive or medication free for at least 2 years. Ten normal volunteers (mean age, 42.5 ± 11.5) served as controls. We used quantitative FDG/PET to calculate global, regional, and normalized rates of glucose metabolism (GMR, rCMRGlc, and rCMRGlc/GMR) in all subjects. The Scaled Subprofile Model (SSM) was used to identify specific patterns of regional metabolic covariation associated with TS. We found that global and regional metabolic rates were normal in TS. SSM analysis identified two TS- related brain networks. One pattern (15.8% variance accounted for, VAF) was characterized by covariate bilateral metab..
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