1,720,960 research outputs found
Evidence of axonal damage in the early stages of multiple sclerosis and its relevance to disability
No full textOBJECTIVE:
To assess axonal damage and its contribution to disability at different stages of multiple sclerosis (MS).
BACKGROUND:
Recent in vivo imaging and in situ pathologic studies have demonstrated that substantial axonal damage accompanies the inflammatory lesions of MS. However, the relation of axonal damage to the duration of MS and its contribution to disability at different stages of the disease remain poorly defined.
DESIGN:
We performed proton magnetic resonance spectroscopic imaging in 88 patients with a wide range of clinical disability and disease duration to measure N-acetylaspartate (NAA, an index of axonal integrity) relative to creatine (Cr) in a large central brain volume that included mostly normal-appearing white matter on magnetic resonance imaging.
RESULTS:
We observed that the NAA/Cr values were abnormally low in the early stages of MS, even before significant disability (measured using the Expanded Disability Status Scale [EDSS]) was evident clinically, and declined more rapidly with respect to EDSS at lower than at higher EDSS scores (P/=5, Spearman rank order correlation = -0.1, P<.9). When similar analyses were performed in patients with MS grouped for duration of disease, the subgroup with early disease duration (<5 years) also showed central brain NAA/Cr resonance intensity ratios significantly lower than healthy controls (P<.001).
CONCLUSION:
Cerebral axonal damage begins and contributes to disability from the earliest stages of the disease
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
Choline is increased in pre-lesional normal appearing white matter in multiple sclerosis.
No full textOBJECTIVE:
Our aim was to determine if the resonance intensity of choline-containing compounds (Cho) measured using proton magnetic resonance spectroscopy (MRS) was increased in pre-lesional normal appearing white matter (NAWM) in patients with multiple sclerosis (MS) relative to NAWM that remained stable in subsequent scans.
BACKGROUND:
The Cho peak in MR spectra is associated with membrane phospholipids and increases in acute MS plaques, possibly even before the appearance of MRI-visible MS lesions.
METHODS:
Three combined proton MRI and MRS imaging examinations of the corpus callosum and adjacent periventricular white matter were performed on 12 MS patients at intervals of 6 months. Proton density (PD) images were visually matched across 3 time points and the lesion volume in each voxel of the volume of interest was determined. The voxels were subdivided into four groups based on the presence or absence of lesion at baseline and change or no change in lesion volume on the subsequent scan.
RESULTS:
We found a significantly higher baseline Cho/Creatine (Cr) ratio in NAWM voxels that displayed MRI visible lesions 6 months later than NAWM voxels that remained unchanged (1.57 +/- 0.30 and 1.37 +/- 0.33, respectively, p < 0.001). The 12-month interval data revealed similar pre-lesional elevated Cho/Cr, (1.51 +/- 0.29 versus 1.39 +/- 0.32, p = 0.009). Voxels that contained lesion at baseline and increased in lesion volume at 6 months also showed a significantly higher Cho/Cr ratio than those whose lesion volume did not change (1.60 +/- 0.32 and 1.49 +/- 0.36, respectively, p = 0.043).
CONCLUSIONS:
The results of this study are consistent with focal pre-lesional myelin membrane pathology in the NAWM at least 12 months before lesions become visible on conventional MRI. This could reflect altered myelin chemistry or the presence of inflammation as seen in experimental allergic encephalomyelitis
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
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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