1,721,772 research outputs found
Tinnitus Is Associated With Improved Cognitive Performance in Non-hispanic Elderly With Hearing Loss
Get PDFBecause hearing loss is a high-risk factor for cognitive decline, tinnitus, a comorbid condition of hearing loss, is often presumed to impair cognition. The present cross-sectional study aimed to delineate the interaction of tinnitus and cognition in the elderly with and without hearing loss after adjusting for covariates in race, age, sex, education, pure tone average, hearing aids, and physical well-being. Participants included 643 adults (60–69 years old; 51.3% females) from the National Health and Nutrition Examination Survey (NHANES, 2011–2012), and 1,716 (60–69 years old; 60.4% females) from the Hispanic Community Health Study (HCHS, 2008–2011). Multivariable linear and binary logistic regression was used to assess the association between tinnitus and cognition in the two sub-cohorts of normal hearing (NHANES, n = 508; HCHS, n = 1264) and hearing loss (NHANES, n = 135; HCHS, n = 453). Cognitive performance was measured as a composite z-score from four cognitive tests: The Consortium to Establish a Registry for Alzheimer’s Disease (CERAD)-word learning, CERAD-animal fluency, CERAD-word list recall, and the digit symbol substitution test (DSST) in NHANES, and a comparable Hispanic version of these four tests in HCHS. Multivariable linear regression revealed no association between tinnitus and cognition, except for the NHANES (non-Hispanic) participants with hearing loss, where the presence of tinnitus was associated with improved cognitive performance (Mean = 0.3; 95% CI, 0.1–0.5; p, 0.018). Using the 25th percentile score of the control (i.e., normal hearing and no tinnitus) as a threshold for poor cognitive performance, the absence of tinnitus increased the risk for poor cognitive performance (OR = 5.6, 95% CI, 1.9–17.2; p, 0.002). Sensitivity analysis found a positive correlation between tinnitus duration and cognitive performance in the NHANES cohort [F(4,140), 2.6; p, 0.037]. The present study finds no evidence for the assumption that tinnitus impairs cognitive performance in the elderly. On the contrary, tinnitus is associated with improved cognitive performance in the non-Hispanic elderly with hearing loss. The present result suggests that race be considered as an important and relevant factor in the experimental design of tinnitus research. Future longitudinal and imaging studies are needed to validate the present findings and understand their mechanisms
Speech recognition with varying numbers and types of competing talkers by normal-hearing, cochlear-implant, and implant simulation subjects
No full textListening in noisy places is challenging, especially with hearing impairment. Unfortunately it is unavoidable in many social, educational and work situations. Speech understanding in continuous noise eg white noise is well understood, but in real life the background is typically people talking. This project used men, women, and children talking to evaluate speech understanding in normal-hearing people, cochlear implant users, and normal-hearing people using a cochlear implant simulation. Results showed that the use of continuous backgrounds underestimates difficulties experienced by cochlear implant users. Children talking in the background was surprisingly demanding, perhaps suggesting an evolutionary trait of not ignoring children
Bimodal hearing benefit for speech recognition with competing voice in cochlear implant subject with normal hearing in contralateral ear
No full textObjectives: This project assessed electroacoustic benefit for speech recognition with a competing talker.Design: Using a cochlear implant subject with normal hearing in the contralateral ear, the contribution of low-pass and high-pass natural sound to speech recognition was systematically measured.Results: High-frequency sound did not improve performance, but low-frequency sound did, even when unintelligible and limited to frequencies below 150 Hz.Conclusions: The low-frequency sound assists separation of the two talkers, presumably using the fundamental frequency cue. Extrapolating this finding to regular cochlear implant users may suggest that using a hearing aid on the contralateral ear will improve performance, even with limited residual hearing
Synthesis of Glyco-Conjugates 1. Synthesis of 2,5-Neuraminic acid dimer 2. Synthesis of Glyco-Conjugates via Olefin Metathesis
No full text本論文中，以探討不同類型醣類化合物的合成為主。在近年來，醣類化學逐漸受到重視，除了發現此類分子是細胞間作用的媒介之外，在藥物的開發上，也佔有很重要的地位。但在傳統的醣類合成上，受到反應條件嚴苛及選擇性的問題影響，以致許多含醣分子的合成較為困難，本論文即分別針對以醣類為主的數種化合物進行合成的改進。
在選擇的幾種醣類化合物中，有生物體內天然的醣類配位基，如海膽卵子表面的2,5聚唾液酸，此為受精作用中不可或缺的媒介，合成此2,5聚唾液酸利用一完全In this thesis, new methods for the synthesis of several different types of glyco-conjugates were developed. The target including natural glyco-conjugated ligand, drug mimetic and derivatives.
2,5-neuraminic acid was chosen as the first target. This glycol-conjugate was a very important signal transductor during fertilization of the sea urchin. Here, an amide bond formation reaction was used to construct the 2,5-neuraminic acid dimer. By this method, glycosidic bond was formed through an exclusive目錄 i
圖目錄 iii
表目錄 iv
簡寫表 v
摘要 viii
第一章 2,5-聚唾液酸的合成 1
緒論 1
結果與討論 8
結論 14
第二章 利用Grubbs試劑合成C-Linked雙醣 15
緒論 15
結果與討論 21
結論 28
第三章 自然殺手T細胞活化劑及衍生物的合成 29
緒論 29
結果與討論 39
結論 62
論文總結論 63
實驗部份 64
參考文獻 12
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
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
Auditory brainstem responses as a biomarker for cognition.
Get PDFA non-invasive, accessible and effective biomarker is critical to the diagnosis, monitoring and treatment of age-related cognitive decline. Recent work has suggested a strong association between auditory brainstem responses (ABR) and cognitive function in aging macaques. Here we show in 118 human participants (66 females; age range=18-92 years; hearing loss = -5 to 70 dB HL) that cognition is associated with both age and hearing level, but this triad relationship is mainly driven by the age factor. After adjusting for age, cognition is still significantly associated with both the ABR wave V amplitude (B, 0.110, 95% CI, 0.018- 0.202; p = 0.020) and latency (B, -0.101, 95% CI, -0.186- -0.016; p = 0.021). Importantly, this age-adjusted ABR-cognition association is primarily driven by older individuals and language-dependent cognitive functions. We also perform the area under the curve (AUC) of the receiver-operating-characteristic analysis and find that the ABR wave V amplitude is best for detecting good cognitive performers (AUC = 0.96) whereas the wave V latency is best for detecting poor ones (AUC = 0.86). The present result not only confirms the previous animal work in humans but also shows the clinical potential of using auditory brainstem responses to improve diagnosis and treatment of age-related cognitive decline
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