1,720,995 research outputs found
Genetics of presbycusis and presbystasis
No full textPresbycusis and presbystasis represent relevant problems of aging, caused by the increase in life expectancy in developed
countries. As such, it is advantageous to better understand the physiopathological mechanisms of these age-related inner
ear diseases. The hypothesis that presbycusis and presbystasis have a genetic background was proposed some years ago.
Several studies (in humans and animals) are available in the literature, and possible genes involved in the physiopathology
of both diseases have been identified. The aim of this paper is to present an overview of the information available in the
current medical literature on presbycusis and presbystasis
Threshold estimation in adult normal- and impaired-hearing subjects using auditory steady-state responses
No full textBACKGROUND: The aim of the study was to compare the estimation of hearing threshold values by behavioral and electrophysiological (ASSR) methods in subjects with normal hearing and those with sensorineural hearing impairment.
MATERIAL/METHODS: Thirty-two subjects (17 male and 15 female) were tested, with a total of 61 ears. Of these, 11 (22 ears) presented normal hearing threshold values (0-19 dBHL) and 21 (39 ears) sensorineural deficits.
RESULTS: The data showed that for the normal-hearing subjects the mean +/-SD ASSR threshold was approximately 20+/-11 dB for frequencies of 0.25-1.0 kHz. For higher frequencies the ASSR threshold increased to 40+/-12.5 dB at 8.0 kHz. Regression analysis confirmed that the difference between the ASSR-estimated and behavioral threshold values decreased significantly with the amount of hearing loss. The data showed that for a 10-dB increment of the behavioral threshold, the ASSR threshold increased by 7 dB. The difference of about 27 dB between the two methods observed in normal subjects tends to cancel in hearing loss greater than 95-100 dBHL.
CONCLUSIONS: The results of these analyses indicate that the threshold estimates are rather discordant with the behavioral thresholds. in particular it seems that the correction factor applied here does not rely on factors adequately modeled (in terms of instrumentation) to compensate for the effects of hearing loss on ASSR thresholds. The threshold estimation is adequately modeled for high levels of hearing loss, particularly for patients requiring a cochlear implant
Idiopathic sudden sensorineural hearing loss: cardiovascular risk factors do not influence hearing threshold recovery
No full textPrevious studies have suggested that risk factors for ischaemic vascular disease, such as cigarette smoking, hypertension and hyperlipidaemia, can also be considered risk factors for the development of idiopathic sudden sensorineural hearing loss (ISSNHL). In this study, we have evaluated the hypothesis that these factors can influence hearing threshold recovery in patients affected by ISSNHL. A total of 141 subjects who suffered an episode of ISSNHL were included. All subjects were assessed with tonal audiometry, auditory brainstem responses and MRI to exclude retrocochlear pathology. Hearing tests were conducted at ISSNHL onset (t = 0) and after 30 days. Patients were divided into three classes according to the presence/absence of one or more cardiovascular risk factors including: history of smoking, total serum cholesterol/triglycerides, history of hypertension and diabetes mellitus. Values of hearing threshold recovery were estimated and comparisons were conducted across the three risk factor classes. 75% of patients affected by ISSNHL showed a threshold recovery.
However, the threshold recovery was found to be class-independent (average recovery value of 18 dB HL per classes) and also independent of age and gender. Even if cardiovascular risk factors have been found to be involved in the pathogenesis of ISSNHL, the present study suggests that these factors do not have any significant influence on the threshold recovery in ISSNHL
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
Estimation of pure-tone thresholds in adults using extrapolated distortion product otoacoustic emission input/output-functions and auditory steady state responses
No full textPure-tone thresholds were used as the reference and compared with extrapolated distortion product otoacoustic emission input/output-functions and auditory steady state responses (ASSR) in hearing-impaired adults, using the Cochlea-Scan and Audera devices. Fifty-three subjects presenting sensorineural deficits were included in the study. The DPOAE data were recorded using the detailed Cochlea-Scan threshold modality, and ASSR responses were assessed at 1.0, 2.0, and 4.0 kHz. The comparison between DPOAE and ASSR threshold values indicated significant mean differences across all tested frequencies. Significant relationships were observed between the behavioral and the DPOAE measurements in the lower frequencies (1.5 and 2.0 kHz). The Cochlea-Scan algorithm seems to overestimate hearing threshold. Logistic regression models (probability of DPOAE response p = 0.9), suggested that the identifiable hearing levels are less than 34 dB HL (at 2.0 and 4.0 kHz) and less or equal to 38 and 40 dB HL at 1.5 and 6.0 kHz respectively. The Cochlea-Scan DPOAE protocols can be used in cases presenting mild hearing deficits (i.e.<40 dB HL)
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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