173 research outputs found
An Investigation and Reduction of Electro-Optical Noise in Tunable Diode Laser
A double FFT (DFFT) procedure is developed to reduce the effect of 1/f noise in the spectrum of Distribution FeedBack (DFB) tunable diode laser. Simulations and experimental results are preformed. An obvious effectiveness of the double FFT on the 1/f noise spectrum has been observed. The 1/f noise was monitored in the three terminals. A linear fitting of the 1/f was verified for Single FFT (SFFT) and (DFFT) to calculate the Frequency Exponent Factor (FEF) ? and the amplitude of 1/f noise. Keywords: Fast Fourier transformation, tunable diode laser, Double Fast Fourier Transfor
The Potential Role of the cABR in Assessment and Management of Hearing Impairment
Hearing aid technology has improved dramatically in the last decade, especially in the ability to adaptively respond to dynamic aspects of background noise. Despite these advancements, however, hearing aid users continue to report difficulty hearing in background noise and having trouble adjusting to amplified sound quality. These difficulties may arise in part from current approaches to hearing aid fittings, which largely focus on increased audibility and management of environmental noise. These approaches do not take into account the fact that sound is processed all along the auditory system from the cochlea to the auditory cortex. Older adults represent the largest group of hearing aid wearers; yet older adults are known to have deficits in temporal resolution in the central auditory system. Here we review evidence that supports the use of the auditory brainstem response to complex sounds (cABR) in the assessment of hearing-in-noise difficulties and auditory training efficacy in older adults
O TRISTE FIM DE LIMA BARRETO E AS IDEALIZAĂĂES DE POLICARPO E O TRISTE FIM DE POLICARPO E AS IDEALIZAĂĂES DE LIMA BARRETO
Este artigo apresenta uma abordagem do romance Triste fim de Policarpo Quaresma atravĂ©s de um olhar sobre a descontinuidade entre a ideologia de alguns personagens e suas respectivas atuaçÔes no universo ficcional. SeguirĂĄ tambĂ©m uma anĂĄlise dos teĂłricos literĂĄrios Alfredo Bosi e Ălvaro Marins acerca das influĂȘncias possĂveis da vida do autor Lima Barreto em sua obra literĂĄria
Effects of Age, Cognition, and Neural Encoding on the Perception of Temporal Speech Cues
Partial funding for Open Access provided by the UMD Libraries' Open Access Publishing Fund.Older adults commonly report difficulty understanding speech, particularly in adverse listening environments. These communication difficulties may exist in the absence of peripheral hearing loss. Older adults, both with normal hearing and with hearing loss, demonstrate temporal processing deficits that affect speech perception. The purpose of the present study is to investigate aging, cognition, and neural processing factors that may lead to deficits on perceptual tasks that rely on phoneme identification based on a temporal cue â vowel duration. A better understanding of the neural and cognitive impairments underlying temporal processing deficits could lead to more focused aural rehabilitation for improved speech understanding for older adults. This investigation was conducted in younger (YNH) and older normal-hearing (ONH) participants who completed three measures of cognitive functioning known to decline with age: working memory, processing speed, and inhibitory control. To evaluate perceptual and neural processing of auditory temporal contrasts, identification functions for the contrasting word-pair WHEAT and WEED were obtained on a nine-step continuum of vowel duration, and frequency-following responses (FFRs) and cortical auditory-evoked potentials (CAEPs) were recorded to the two endpoints of the continuum. Multiple linear regression analyses were conducted to determine the cognitive, peripheral, and/or central mechanisms that may contribute to perceptual performance. YNH participants demonstrated higher cognitive functioning on all three measures compared to ONH participants. The slope of the identification function was steeper in YNH than in ONH participants, suggesting a clearer distinction between the contrasting words in the YNH participants. FFRs revealed better response waveform morphology and more robust phase-locking in YNH compared to ONH participants. ONH participants also exhibited earlier latencies for CAEP components compared to the YNH participants. Linear regression analyses revealed that cortical processing significantly contributed to the variance in perceptual performance in the WHEAT/WEED identification functions. These results suggest that reduced neural precision contributes to age-related speech perception difficulties that arise from temporal processing deficits
In situ evaluation of fluoride-, stannous- and polyphosphate-containing solutions against enamel erosion
Objective
To evaluate the anti-erosive effect of solutions containing sodium fluoride (F: 225 ppm of fluoride), sodium fluoride + stannous chloride (F + Sn: 225 ppm of fluoride + 800 ppm of stannous), sodium fluoride + stannous chloride + sodium linear polyphosphate (F + Sn + LPP: 225 ppm of fluoride + 800 ppm of stannous + 2% of sodium linear polyphosphate), and deionized water (C: control), using a four-phase, single-blind, crossover in situ clinical trial.
Methods
In each phase, 12 volunteers wore appliances containing 4 enamel specimens, which were submitted to a 5-day erosion-remineralization phase that consisted of 2 h of salivary pellicle formation with the appliance in situ, followed by 2 min extra-oral immersion in 1% citric acid (pH 2.4), 6x/day, with 90 min of exposure to saliva in situ between the challenges. Treatment with the test solutions was performed extra-orally for 2âmin, 2x/day. At the end of the experiment, surface loss (SL, in ÎŒm) was evaluated by optical profilometry. Data were analyzed using ANOVA and Tukey tests (α = 0.05). The surface of additional specimens was evaluated by x-ray diffraction after treatments (n = 3).
Results
C (mean SL ± standard-deviation: 5.97 ± 1.70) and F (5.36 ± 1.59) showed the highest SL, with no significant difference between them (p > 0.05). F + Sn (2.68 ± 1.62) and F + Sn + LPP (2.10 ± 0.95) did not differ from each other (p > 0.05), but presented lower SL than the other groups (P < 0.05). Apatite and stannous deposits on specimen surfaces were identified in the x-ray analysis for F + Sn and F + Sn + LPP.
Conclusions
Sodium fluoride solution exhibited no significant anti-erosive effect. The combination between sodium fluoride and stannous chloride reduced enamel erosion, irrespective of the presence of linear sodium polyphosphate.
Clinical significance
Under highly erosive conditions, sodium fluoride rinse may not be a suitable alternative to prevent enamel erosion. A rinse containing sodium fluoride and stannous chloride was shown to be a better treatment option, which was not further improved by addition of the sodium linear polyphosphate
Age-Related Temporal Processing Deficits in Word Segments in Adult Cochlear-Implant Users
Partial funding for Open Access provided by the UMD Libraries' Open Access Publishing Fund.Aging may limit speech understanding outcomes in cochlear-implant (CI) users. Here, we examined age-related declines in auditory temporal processing as a potential mechanism that underlies speech understanding deficits associated with aging in CI users. Auditory temporal processing was assessed with a categorization task for the words dish and ditch (i.e., identify each token as the word dish or ditch) on a continuum of speech tokens with varying silence duration (0 to 60âms) prior to the final fricative. In Experiments 1 and 2, younger CI (YCI), middle-aged CI (MCI), and older CI (OCI) users participated in the categorization task across a range of presentation levels (25 to 85âdB). Relative to YCI, OCI required longer silence durations to identify ditch and exhibited reduced ability to distinguish the words dish and ditch (shallower slopes in the categorization function). Critically, we observed age-related performance differences only at higher presentation levels. This contrasted with findings from normal-hearing listeners in Experiment 3 that demonstrated age-related performance differences independent of presentation level. In summary, aging in CI users appears to degrade the ability to utilize brief temporal cues in word identification, particularly at high levels. Age-specific CI programming may potentially improve clinical outcomes for speech understanding performance by older CI listeners
The association of plant-based dietary patterns with visceral adiposity, lipid accumulation product, and triglyceride-glucose index in Iranian adults
Perfil sorolĂłgico do vĂrus John Cunningham (JCV) em pacientes com esclerose mĂșltipla
Treatment options for multiple sclerosis (MS) have changed over the last few years, bringing about a new category of drugs with more efficient profiles. However, these drugs have come with a whole new profile of potential adverse events that neurologists have to learn well and quickly. One of the most feared complications of these MS treatments is progressive multifocal leukoencephalopathy caused by the reactivation of the John Cunningham virus (JCV). Objective: To identify the serologic profile of JCV in patients with MS. Methods: Data on serum antibodies for JCV were obtained using the enzyme-linked immunosorbent assay provided by the STRATIFY-JCV program. Results: A total of 1,501 blood tests were obtained from 1,102 patients with MS. There were 633 patients (57.1%) who were positive for antibodies for JCV and 469 patients who were negative (42.9%). Twenty-three patients became positive after initially having negative JCV antibody status. The rate of seroconversion was 18.5% over 22 months. Conclusion: The JCV serologic profile and seroconversion in Brazilian patients were similar to those described in other countries.As opçÔes terapĂȘuticas para esclerose mĂșltipla (EM) modificaram-se ao longo dos Ășltimos anos, trazendo uma nova categoria de drogas com melhor perfil de eficĂĄcia. No entanto, estas drogas vieram com um novo perfil de potenciais eventos adversos que exigem que o neurologista os reconheça bem e rapidamente. Uma das complicaçÔes mais temidas destes tratamentos para a EM Ă© a leucoencefalopatia multifocal progressiva (LEMP), causada pela reativação do vĂrus John Cunningham (JCV). Objetivo: Identificar o perfil sorolĂłgico de JCV em pacientes com EM. MĂ©todos: Dados sorolĂłgicos de JCV foram obtidos atravĂ©s do ensaio por enzimas imuno-adsorvidas (ELISA) fornecido pelo programa STRATIFY-JCV. Resultados: Um total de 1.501 testes sanguĂneos foram obtidos de 1.102 pacientes com EM. O grupo teve 633 pacientes (57,1%) soropositivos para anticorpos anti-JCV e 469 pacientes negativos (42,9%). Vinte e trĂȘs pacientes se tornaram posivitos apĂłs resultados iniciais negativos para anticorpos anti-JCV. A taxa de soroconversĂŁo foi 18,5% em 22 meses. ConclusĂŁo: O perfil sorolĂłgico do JCV e a soroconversĂŁo nos pacientes brasileiros foi semelhante Ă quela descrita em outros paĂses
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