1,720,961 research outputs found
Vestibular evoked myogenic and periocular potentials after vestibular schwannoma surgery
No full textObjectives: We analyzed the behavior of preoperative and postoperative vestibular evoked myogenic potentials (VEMPs) and vestibular evoked periocular potentials (VEPPs) in 3 patients who had vestibular schwannoma and underwent modified translabyrinthine surgery. Methods: We compared VEMPs and VEPPs, measured with both air-conducted (AC) and bone-conducted (BC) stimulations. Vestibular evoked potentials were measured both in the immediate postoperative period and some months later. Results: At the immediate postoperative examination, VEPPs were preserved in all 3 patients with both AC and BC stimulations. The VEMPs showed stable or improved parameters in 2 of our patients and were absent in the third patient. At the follow-up examination, VEMPs did not show any significant change with respect to the previous evaluation: In contrast, VEPPs were absent in 2 of our patients with AC stimulation and in I patient with BC stimulation. Conclusions: Our results seem to indicate a greater stability and reproducibility of VEMPs compared with VEPPs. In 1 patient, who had a schwannoma of the inferior vestibular nerve, the preservation of VEPPs and the absence of VEMPs in the immediate postoperative period confirm that the saccule represents the origin of VEMPs. Furthermore, these results suggest that not only the saccule, but also the utriculus, could be implicated in the origin of VEPPs
Modified translabyrinthine approach and hearing preservation: imaging evaluation.
No full textTo establish if the computed tomography (CT) and magnetic resonance imaging (MRI) appearances of the vestibule, after the removal of vestibular schwannoma by a modified translabyrinthine approach, correlate with a successful outcome, defined as hearing preservation. Our study group consisted of 16 patients with vestibular schwannoma. All patients' pre-operative hearing was graded as class one or two according to the Gardner-Robertson scale. On MRI scans, the schwannoma, including the intracanalicular segment, were less than 2 cm in size in all the patients. The intracanalicular portion involved the fundus of the internal auditory canal in seven patients. In the remaining nine patients, the schwannoma had spread to involve two-thirds of the meatus, sparing its lateral third. The state of the labyrinth, in particular the integrity of the vestibule, was evaluated by CT scans and MRI prior to and following surgery. The schwannoma was completely removed in all patients. None showed any signs of persistence or tumoral relapse on the post-operative MRI. The final follow up showed that seven patients had maintained their hearing function (i.e. four patients with class one hearing and three with class two). The MRI vestibular signal on the T2-weighted images was well depicted only in patients with hearing preservation. Bony vestibular integrity was observed in the CT scans of all cases with hearing preservation, and also in three cases with failure of hearing preservation. Our results confirm that total isolation and maintenance of an anatomically intact vestibule, as depicted by MRI examination, is one of the fundamental factors for successful preservation of hearing function following modified translabyrinthine approach schwannoma removal
Selective damage of the vestibular apparatus following toxic effects of streptomycin
No full text[No abstract available
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
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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