1,720,992 research outputs found
Beyond focal cortical lesions in MS: an in vivo quantitative and spatial imaging study at 7T
Get PDFObjectives: Using quantitative T2* 7-tesla (7T) MRI as a marker of demyelination and iron loss, we
investigated, in patients with relapsing-remitting multiple sclerosis (RRMS) and secondary progressive
multiple sclerosis (SPMS), spatial and tissue intrinsic characteristics of cortical lesion(s)
(CL) types, and structural integrity of perilesional normal-appearing cortical gray matter (NACGM)
as a function of distance from lesions.
Methods: Patients with MS (18 RRMS, 11 SPMS), showing at least 2 CL, underwent 7T T2*
imaging to obtain (1) magnitude images for segmenting focal intracortical lesion(s) (ICL) and
leukocortical lesion(s) (LCL), and (2) cortical T2* maps. Anatomical scans were collected at 3T
for cortical surface reconstruction using FreeSurfer. Seventeen age-matched healthy participants
served as controls.
Results: ICL were predominantly located in sulci of frontal, parietal, and cingulate cortex; LCL distribution
was more random. In MS, T2* was higher in both ICL and LCL, indicating myelin and iron
loss, than in NACGM (p , 0.00003) irrespective of CL subtype and MS phenotype. T2* was
increased in perilesional cortex, tapering away from CL toward NACGM, the wider changes being
for LCL in SPMS. NACGM T2* was higher in SPMS relative to RRMS (p 5 0.006) and healthy
cortex (p 5 0.02).
Conclusions: CL had the same degree of demyelination and iron loss regardless of lesion subtype
and disease stage. Cortical damage expanded beyond visible CL, close to lesions in RRMS, and
more diffusely in SPMS. Evaluation of NACGM integrity, beyond focal CL, could represent a surrogate
marker of MS progression
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
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
The association between intra- and juxta-cortical pathology and cognitive impairment in multiple sclerosis by quantitative T2* mapping at 7T MRI
Get PDFAbstractUsing quantitative T2* at 7Tesla (T) magnetic resonance imaging, we investigated whether impairment in selective cognitive functions in multiple sclerosis (MS) can be explained by pathology in specific areas and/or layers of the cortex.Thirty-one MS patients underwent neuropsychological evaluation, acquisition of 7T multi-echo T2* gradient-echo sequences, and 3T anatomical images for cortical surfaces reconstruction. Seventeen age-matched healthy subjects served as controls.Cortical T2* maps were sampled at various depths throughout the cortex and juxtacortex. Relation between T2*, neuropsychological scores and a cognitive index (CI), calculated from a principal component analysis on the whole battery, was tested by a general linear model.Cognitive impairment correlated with T2* increase, independently from white matter lesions and cortical thickness, in cortical areas highly relevant for cognition belonging to the default-mode network (p<0.05 corrected). Dysfunction in different cognitive functions correlated with longer T2* in selective cortical regions, most of which showed longer T2* relative to controls. For most tests, this association was strongest in deeper cortical layers. Executive dysfunction, however, was mainly related with pathology in juxtameningeal cortex. T2* explained up to 20% of the variance of the CI, independently of conventional imaging metrics (adjusted-R2: 52–67%, p<5.10−4).Location of pathology across the cortical width and mantle showed selective correlation with impairment in differing cognitive domains. These findings may guide studies at lower field strength designed to develop surrogate markers of cognitive impairment in MS
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
White matter paramagnetic rim and non-rim lesions share a periventricular gradient in multiple sclerosis: A 7-T imaging study
No full textBackground: Paramagnetic rim white matter (WM) lesions (PRL) are thought to be a main driver of non-relapsing multiple sclerosis (MS) progression. It is unknown whether cerebrospinal fluid (CSF)-soluble factors diffusing from the ventricles contribute to PRL formation. Objective: To investigate the distribution of PRL and non-rim brain WM lesions as a function of distance from ventricular CSF, their relationship with cortical lesions, the contribution of lesion phenotype, and localization to neurological disability. Methods: Lesion count and volume of PRL, non-rim WM, leukocortical lesion (LCL), and subpial/intracortical lesions were obtained at 7-T. The brain WM was divided into 1-mm-thick concentric rings radiating from the ventricles to extract PRL and non-rim WM lesion volume from each ring. Results: In total, 61 MS patients with ⩾1 PRL were included in the study. Both PRL and non-rim WM lesion volumes were the highest in the periventricular WM and declined with increasing distance from ventricles. A CSF distance-independent association was found between non-rim WM lesions, PRL, and LCL, but not subpial/intracortical lesions. Periventricular non-rim WM lesion volume was the strongest predictor of neurological disability. Conclusions: Non-rim and PRL share a gradient of distribution from the ventricles toward the cortex, suggesting that CSF proximity equally impacts the prevalence of both lesion phenotypes
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