1,720,964 research outputs found
Acute demyelinating sensorimotor polyneuropathy in B-cell lymphoma with IGM autoantibodies against glycolipid GD1B
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Neurofibromatous neuropathy: An ultrastructural study
No full textNeurofibromatosis 1 (NF1) is a common genetic disorder
characterized by the presence of neurofibromas
arising from the proliferation of Schwann cells (SC) and
perineurial cells. At variance with NF2, the incidence of an
associated polyneuropathy is very low in NF1, and its
histopathological features are poorly characterized. We
report the sporadic case of a 46-year-old woman presenting
with bilateral subclavicular painful masses. MRI
showed bilateral plexiform lesions extending from cervical
roots to the elbows; a malignant nature of lesions was
ruled out by PET-TC. A biopsy of the larger lesion had
histological features of plexiform neurofibroma. Although
the patient had no peripheral nerve symptoms, nerve conduction
studies documented a sensory-motor polyneuropathy,
which was confirmed by sural nerve biopsy.
Electron microscopy showed dramatic loss of large and
small myelinated, as well as unmyelinated axons together
with numerous regeneration clusters. An increased number
of fibroblast cell processes and a large amount of
collagen fibrils characterized the endoneurium. A combined
involvement of myelinating and non-myelinating SC
was evidenced by the high frequency of alterations such
as: irregularities and degradation figures of myelin, lipofuscin
deposition, pseudo-onion bulb structures and collagen
pockets substituting unmyelineted axons. These changes
suggest that in neurofibromatous neuropathy, a widespread
axonal degeneration takes place independently of
the presence of tumoral infiltration, possibly due to an
impairment in SC-axon cross-talk
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
Upper motor neuron involvement in X-linked recessive bulbospinal muscular atrophy
No full textObjective: Clinicopathological findings of X-linked recessive bulbospinal muscular atrophy (SBMA) are
indicative of lower motor neuron and primary sensory neuron involvement. The aim of our study was to
investigate the presence of subclinical upper motor neuron (UMN) dysfunction in this disease.
Methods: Two siblings with clinical presentation, routine electrophysiological tests, histopathological
features of muscle and nerve biopsies and genetic testing consistent with diagnosis of SBMA underwent
transcranial magnetic stimulation (TMS). The analysed parameters were motor evoked potential (MEP)
threshold, silent period (SP) and central motor conduction time. Intracortical inhibition with paired pulses
from 1 to 6 ms interstimulus intervals (ISIs) was evaluated in the older brother.
Results: MEP parameters were significantly altered in limb and cranial muscles and MEP suppression after
paired stimulation significantly reduced in the older brother. MEP abnormalities were present in one
lower limb, but SP abolished in all limbs, in the younger brother.
Conclusions: Subclinical involvement of UMNs may be present in patients affected by SBMA. This finding
suggests that the array of neuronal systems whose function may be affected by the pathogenic process of
SBMA is larger than it was considered so far.
Significance: TMS is a sensitive diagnostic tool for the identification of UMN dysfunction and should be
included in the diagnostic evaluation of patients with SBMA
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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