1,720,965 research outputs found
The evaluation of a complete diagnosis of cerebrovascular damage in patients with homozygous familial hypercholesterolemia
No full textAcute encephalitis of unknown etiology: early diagnosis and follow-up of disease evolution. MRI. A pictorial assay
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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
Acute encephalitis of unknown etiology: Early diagnosis and follow-up of disease evolution. MRI. A pictorial essay
No full textTwo women with viral encephalitis of unknown etiology were studied with serial MR studies at 1.5 Tesla using: Spin-Echo (SE) T1-weighted (T1w) sequences before and after i.v. administration of paramagnetic contrast agent, with/without magnetization transfer (MT), Fast SE and Fluid-attenuated Inversion Recovery (FLAIR) T2-weighted sequences, Echo-Planar Single-Shot sequences for the assessment of water diffusivity (Diffusion Weighted, DW, and Apparent Diffusion Coefficient maps, ADC). The DW and T1w sequences with MT after contrast were most useful to detect the initial pathologic alterations, thereby reinforcing the clinical diagnostic hypothesis and prompting appropriate drug treatment, even if the laboratory data were not conclusive for viral etiology. In a later phase, both cases showed MR evidence of lacunar foci in the grey matter, and cortical laminar necrosis, probably indicating a concomitant hypoxic/ischemic mechanis
A case of Neurofibromatosis Type I "complicated" by a malignant cerebellar expanding process with atypical CT/MR features [Un caso di Neurofibromatosi di Tipo 1 "complicata" da processo espansivo cerebellare maligno con aspetti TC/RM atipici]
No full textA 13 year-old boy, previously diagnosed as having Neurofibromatosis Type 1 (NF1) but otherwise healthy, was referred to our Department for headache, vomiting, ataxia and VI-VII left cranial nerve palsy. Emergency head CT scan was performed, immediately followed by contrast-enhanced MR scan with Echo-Planar (EPI) water diffusibility study. A large ovalar mass lesion was evident in the left cerebellar hemisphere, hyperdense on CT, hypointense in T2-weighted images, isointense to grey matter in FLAIR and T1-weighted images, with clear mass effect on the surrounding structures, but only mild peripheral contrast-enhancement in the anterior part of the mass, these features resembling those of a desmoplastic medulloblastoma. However, the EPI Diffusion-weighted images (DWI) and corresponding Apparent Diffusion Coefficient (ADC) maps consistently showed increased water diffusivity, a pattern not compatible with the dense cell-packing typical of medulloblastomas. The pathological analysis of the surgical specimen indeed showed focal neoplastic cell clusters interspersed in a diffusely altered cerebellar cortex. Neoplastic cells exhibited large eosinophilic cytoplasma, hyperchromatic and multinucleolated nuclei, and frequent mitoses, a pattern indicative of anaplastic astrocytoma. The case presented supports the evidence that NF1 is associated with increased risk of developing several different neoplasms, beside the well-known pilocytic astrocytomas of the optic pathway. As these neoplasms may exhibit misleading imaging features at CT or " conventional" MRI study, the assessment of water diffusivity may provide useful data for reaching a correct pre-operative diagnosis, since it reflects the histological architecture of the neoplastic tissu
Non-oncological neuroradiological manifestations in nf1 and their clinical implications
No full textNeurofibromatosis type 1 (NF1), the most frequent phakomatosis and one of the most common inherited tumor predisposition syndromes, is characterized by several manifestations that pervasively involve central and peripheral nervous system structures. The disorder is due to mutations in the NF1 gene, which encodes for the ubiquitous tumor suppressor protein neurofibromin; neurofibromin is highly expressed in neural crest derived tissues, where it plays a crucial role in regulating cell proliferation, differentiation, and structural organization. This review article aims to provide an overview on NF1 non-neoplastic manifestations of neuroradiological interest, involving both the central nervous system and spine. We also briefly review the most recent MRI functional findings in NF1
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
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