1,721,050 research outputs found
The radiology of paragangliomas of the skull base
No full textParagangliomas are rare tumors of unknown etiology arising from paraganglionic cells in relation to nerves and blood vessels. They are slow growing benign tumors capable of producing paraneoplastic syndromes due to production of hormones. Malignant transformation is extremely rare. The cornerstone of diagnosis of these tumors in the skull base region is imaging. Biopsy is not appropriate as these tumors are extremely vascular and bleed profusely. Four types of paragangliomas are described in the skull base region including glomus tympanicum, glomus jugulare, glomus vagale and carotid body tumors. It is important to differentiate the four types of tumors in order to decide the most appropriate surgical approach for the excision of the tumors. Differences in expansion and invasion may be delineated radiologically and hence morbidity with respect to involvement of the lower cranial nerves may be predicted. It is also possible to decide the best time for surgical intervention in those tumors where a 'wait and watch' policy is exercised. A radiological staging classification is also possible that may help decide the most appropriate modality of management. We describe here, with clinical examples, the characteristic imaging features of the four types of paragangliomas using high resolution Computerized Tomographie scanning (HRCT) and Magnetic Resonance Imaging techniques (MRI).</p
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
Chronic cerebrospinal fluid leak into skull base causing intramedullary osteolysis
No full textWe present the rare case of a 74-year-old woman with extensive intramedullary osteolysis of the petroclival skull base straddling both sides of the basi-occiput and basi-sphenoid. She presented with clinical features of recurrent spontaneous cerebrospinal fluid (CSF) otorrhoea despite three previous attempts at repair of the CSF leak. Recent advances in imaging techniques enable accurate radiological diagnosis of skull base lesions. We performed T1- and T2-weighted magnetic resonance (MR) images, a fluid attenuated inversion recovery (FLAIR) sequence MR, and a diffusion scan to study the characteristics of the skull base pathology. This revealed extensive osteolysis, with cystic spaces within the clivus and the petrous pyramid extending also to the basi-occiput. The leak was sealed using the technique of subtotal petrosectomy with obliteration of the eustachian tube and blind pit closure of the ear canal. The patient has been followed up for six months with no recurrence of symptoms.</p
The crucial role of imaging in detection of facial nerve haemangiomas
No full textFacial nerve haemangioma is a rare benign neoplasm accounting for 0.7 per cent of all tumours involving the temporal bone. The diagnosis of a facial nerve tumour is often missed or delayed. Early diagnosis is imperative as it influences the eventual outcome for facial nerve function. Prognosis is related to the size of the tumour, the severity and the duration of pre-operative paralysis. The definitive diagnosis of a facial nerve tumour rests exclusively with high resolution imaging of the temporal bone using enhanced magnetic resonance imaging (MRI) and thin-sectioned computed tomography (CT). This case emphasizes the crucial role that high quality imaging can play in the diagnosis of facial nerve tumours, and elegantly illustrates the imaging features of facial nerve haemangiomas.</p
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
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