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1.
Hear Res ; 445: 108992, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38492447

RESUMEN

Noise sensitivity and hyperacusis are decreased sound tolerance conditions that are not well delineated or defined. This paper presents the correlations and distributions of the Noise Sensitivity Scale (NSS) and the Hyperacusis Questionnaire (HQ) scores in two distinct large samples. In Study 1, a community-based sample of young healthy adults (n = 103) exhibited a strong correlation (r = 0.74) between the two questionnaires. The mean NSS and HQ scores were 54.4 ± 16.9 and 12.5 ± 7.5, respectively. NSS scores displayed a normal distribution, whereas HQ scores showed a slight positive skew. In Study 2, a clinical sample of Veterans with or without clinical comorbidities (n = 95) showed a moderate correlation (r = 0.58) between the two questionnaires. The mean scores were 66.6 ± 15.6 and 15.3 ± 7.3 on the NSS and HQ, respectively. Both questionnaires' scores followed a normal distribution. In both samples, participants who self-identified as having decreased sound tolerance scored higher on both questionnaires. These findings provide reference data from two diverse sample groups. The moderate to strong correlations observed in both studies suggest a significant overlap between noise sensitivity and hyperacusis. The results underscore that NSS and HQ should not be used interchangeably, as they aim to measure distinct constructs, however to what extent they actually do remains to be determined. Further investigation should distinguish between these conditions through a comprehensive psychometric analysis of the questionnaires and a thorough exploration of psychoacoustic, neurological, and physiological differences that set them apart.


Asunto(s)
Hiperacusia , Acúfeno , Adulto , Humanos , Hiperacusia/diagnóstico , Encuestas y Cuestionarios , Sonido , Psicoacústica
2.
Int J Audiol ; 62(6): 489-499, 2023 06.
Artículo en Inglés | MEDLINE | ID: mdl-35549972

RESUMEN

OBJECTIVE: Hyperacusis is known as a reduced tolerance to sounds perceived as normal to the majority of the population. There is currently no agreed definition, diagnostic tool, or objective measure of its occurrence. The purpose of this review is to catalogue the research to date on the use of auditory evoked potentials (AEP) to assess hyperacusis. DESIGN: A step-by-step methodology was conducted following guidelines. Four databases were searched. A total of 3343 papers were identified. A final yield of 35 articles were retained for analysis. RESULTS: The analysis identified four types of aetiologies to describe the hyperacusic population in AEP studies; developmental disorders (n = 19), neurological disorders (n = 3), induced hearing damage (n = 8) and idiopathic aetiology (n = 5). Electrophysiological measures were of short (n = 16), middle (n = 13) and long (n = 19) latencies, believed to reflect the activity of the ascending and descending pathways of the auditory system from periphery to cortex. CONCLUSIONS: The results of this review revealed the potential use of electrophysiological measures for further understanding the mechanisms of hyperacusis. However, according to the disparity of concepts to define hyperacusis, definitions and populations need to be clarified before biomarkers specific to hyperacusis can be identified.


Asunto(s)
Audición , Hiperacusia , Humanos , Hiperacusia/diagnóstico , Hiperacusia/etiología , Potenciales Evocados Auditivos , Sonido , Biomarcadores
3.
Sci Technol Adv Mater ; 22(1): 583-596, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34377085

RESUMEN

The interplay between charges and spins may influence the dynamics of the carriers and determine their thermoelectric properties. In that respect, magneto-thermoelectric power MTEP, i.e. the measurements of the Seebeck coefficient S under the application of an external magnetic field, is a powerful technique to reveal the role of magnetic moments on S. This is illustrated by different transition metal chalcogenides: CuCrTiS4 and CuMnTiS4 magnetic thiospinels, which are compared with magnetic oxides, Curie-Weiss (CW) paramagnetic misfit cobaltites, ruthenates, either ferromagnetic perovskite or Pauli paramagnet quadruple perovskites, and CuGa1-x Mn x Te2 chalcopyrite telluride and Bi1.99Cr0.01Te3 in which diluted magnetism is induced by 3%-Mn and 1%-Cr substitution, respectively. In the case of a ferromagnet (below TC) and CW paramagnetic materials, the increase of magnetization at low T when a magnetic field is applied is accompanied by a decrease of the entropy of the carriers and hence S decreases. This is consistent with the lack of MTEP in the Pauli paramagnetic quadruple perovskites. Also, no significant MTEP is observed in CuGa1-x Mn x Te2 and Bi1.99Cr0.01Te3, for which Kondo-type interaction between magnetic moments and carriers prevails. In contrast, spin glass CuCrTiS4 exhibits negative MTEP like in ferromagnetic ruthenates and paramagnetic misfit cobaltites. This investigation of some chalcogenides and oxides provides key ingredients to select magnetic materials for which S benefits from spin entropy.

4.
Science ; 373(6558): 1017-1022, 2021 08 27.
Artículo en Inglés | MEDLINE | ID: mdl-34446603

RESUMEN

The thermal conductivity of crystalline materials cannot be arbitrarily low, as the intrinsic limit depends on the phonon dispersion. We used complementary strategies to suppress the contribution of the longitudinal and transverse phonons to heat transport in layered materials that contain different types of intrinsic chemical interfaces. BiOCl and Bi2O2Se encapsulate these design principles for longitudinal and transverse modes, respectively, and the bulk superlattice material Bi4O4SeCl2 combines these effects by ordering both interface types within its unit cell to reach an extremely low thermal conductivity of 0.1 watts per kelvin per meter at room temperature along its stacking direction. This value comes within a factor of four of the thermal conductivity of air. We demonstrated that chemical control of the spatial arrangement of distinct interfaces can synergically modify vibrational modes to minimize thermal conductivity.

5.
Prog Brain Res ; 262: 57-91, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33931195

RESUMEN

Tinnitus and hyperacusis are two debilitating conditions that are highly comorbid. It has been postulated that they may originate from similar pathophysiological mechanisms such as an increase in central gain. Interestingly, sound stimulation has been shown to reduce central gain and is currently used for the treatment of both conditions. This study investigates the effect of sound stimulation on both tinnitus and hyperacusis in the same patients. Two distinct series of tinnitus participants were tested: one with normal or near-normal hearing (n=16) and one with hearing loss (n=14). A broadband noise shaped to cover most of the tinnitus frequency spectrum was delivered through hearing aids using the noise generator feature (no amplification) and verified through real-ear measurements. Participants received sound stimulation for 3 weeks and were tested before (at baseline), then after 1 week and at the end of the 3 weeks of sound stimulation. There was also a 1-month follow-up after the end of the stimulation protocol. The measurements included self-reported measures of tinnitus and hyperacusis (VAS), validated questionnaires (THI, HQ) and psychoacoustic measurements (tinnitus battery and loudness functions). On both self-assessment (VAS of sound tolerance and tinnitus loudness) and psychoacoustic measures (loudness function and tinnitus loudness in dB), about 50% of tinnitus participants had a synchronous (either a decrease or an increase) modulation of hyperacusis and tinnitus loudness after 1 week and 3 weeks of acoustic stimulation and up to about 70% of participants at 1-M follow-up. The decrease of hyperacusis and tinnitus loudness was more prevalent in normal-hearing participants. There was a significant increase in tinnitus loudness during and following the stimulation in the group with hearing loss. Hyperacusis improvement as assessed by loudness function was significantly correlated with the intensity level of the acoustic stimulation (dB level of the noise produced by the noise generator) in tinnitus participants with normal/near-normal hearing thresholds. Our study partly supports the central gain hypothesis by showing synchronous modulation of hyperacusis and tinnitus loudness. It also shows beneficial effects of acoustic stimulation in some tinnitus individuals, in particular those with normal or near-normal hearing, while highlighting the importance of a careful fitting of sound generators to prevent increase. Since the amplification feature was not turned on in our study, future work should determine whether amplification alone, or in addition to acoustic stimulation (sound generators), would benefit to those with hearing loss.


Asunto(s)
Pérdida Auditiva , Acúfeno , Estimulación Acústica , Audición , Humanos , Hiperacusia/complicaciones , Hiperacusia/terapia , Acúfeno/complicaciones , Acúfeno/terapia
6.
Curr Top Behav Neurosci ; 51: 461-483, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33665781

RESUMEN

This volume has highlighted the many recent advances in tinnitus theory, models, diagnostics, therapies, and therapeutics. But tinnitus knowledge is far from complete. In this chapter, contributors to the Behavioral Neuroscience of Tinnitus consider emerging topics and areas of research needed in light of recent findings. New research avenues and methods to explore are discussed. Issues pertaining to current assessment, treatment, and research methods are outlined, along with recommendations on new avenues to explore with research.


Asunto(s)
Neurociencias , Acúfeno , Humanos , Acúfeno/terapia
7.
Curr Top Behav Neurosci ; 51: 349-359, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33608859

RESUMEN

In this chapter, I address the topic of tinnitus in the context of the patient's trajectory of care, with special attention to psychological comorbidities. Although most patients will cope with tinnitus and need no more than information and reassurance from professionals, a proportion of patients will need more supportive management. Assessment of psychological comorbidities is important to determine how urgent they should be seen in the clinic and their specific needs. The most frequent complaints are stress, depression, and anxiety. Although the direction of this relationship is still unclear (are comorbidities at the origin of tinnitus or are they a consequence of it), it is evident that the more serious comorbidities are at the onset of tinnitus, the worse the prognosis. Therefore, an assessment at the initial visit in the clinic is of utmost importance. There are valid and reliable psychometric tools to quickly draw a portrait of the psychological state of patients that can be used by audiologists, psychologists, or doctors. Therapeutic avenues can then be discussed with the patients to ensure them the best support possible.


Asunto(s)
Acúfeno , Ansiedad , Trastornos de Ansiedad , Comorbilidad , Humanos , Estrés Psicológico , Acúfeno/epidemiología
8.
Psychophysiology ; 58(3): e13755, 2021 03.
Artículo en Inglés | MEDLINE | ID: mdl-33355931

RESUMEN

The Gap Prepulse Inhibition of the Acoustic Startle Reflex (GPIAS) is a paradigm used to assess auditory temporal processing in both animals and humans. It consists of the presentation of a silent gap embedded in noise and presented a few milliseconds before a startle sound. The silent gap produces the inhibition of the startle reflex, a phenomenon called gap-prepulse inhibition (GPI). This paradigm is also used to detect tinnitus in animal models. The lack of inhibition by the silent gaps is suggested to be indicative of the presence of tinnitus "filling-in" the gaps. The current research aims at improving the GPIAS technique by comparing the GPI produced by monaural versus binaural silent gaps in 29 normal-hearing subjects. Two gap durations (5 or 50 ms), each embedded in two different frequency backgrounds (centered around 500 or 4 kHz). Both low- and high- frequency narrowband noises had a bandwidth of half an octave. Overall, the startle magnitude was greater for the binaural versus the monaural presentation, which might reflect binaural loudness summation. In addition, the GPI was similar between the monaural and the binaural presentations for the high-frequency background noise. However, the GPI was greater for the low-frequency background noise for the binaural, compared to the monaural, presentation. These findings suggest that monaural GPIAS might be more suited to detect tinnitus compared to the binaural presentation.


Asunto(s)
Percepción Auditiva/fisiología , Inhibición Prepulso/fisiología , Reflejo de Sobresalto/fisiología , Percepción del Tiempo/fisiología , Estimulación Acústica , Adulto , Parpadeo/fisiología , Electromiografía , Femenino , Humanos , Masculino , Adulto Joven
9.
Otolaryngol Clin North Am ; 53(4): 563-582, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32334868

RESUMEN

The results showed a trend of increased post-gap amplitudes and reduced gap salience; however, the small number of articles yield and limited consensus prohibit any conclusions for clinical use. Nevertheless, gap-induced EPs may be further explored as a potential tool for tinnitus detection.


Asunto(s)
Conducta Animal , Pruebas Auditivas/métodos , Reflejo de Sobresalto , Detección de Señal Psicológica , Acúfeno/diagnóstico , Estimulación Acústica , Adaptación Psicológica , Animales , Modelos Animales de Enfermedad , Electrofisiología , Humanos , Inhibición Prepulso , Acúfeno/fisiopatología
10.
Philos Trans A Math Phys Eng Sci ; 377(2152): 20180337, 2019 Aug 26.
Artículo en Inglés | MEDLINE | ID: mdl-31280719

RESUMEN

The strong interplay between magnetism and transport can tune the thermoelectric properties in chalcogenides and oxides. In the case of ferromagnetic CoS2 pyrite, it was previously shown that the power factor is large at room temperature, reaching 1 mW m-1 K-2 and abruptly increases for temperatures below the Curie transition ( TC), an increase potentially due to a magnonic effect on the Seebeck ( S) coefficient. The too large thermal conductivity approximately equal to 10.5 W m-1 K-1 at room temperature prevents this pyrite from being a good thermoelectric material. In this work, samples belonging to the Co1- xFe xS2 pyrite family ( x = 0, 0.15 and 0.30) have thus been investigated in order to modify the thermal properties by the introduction of disorder on the Co site. We show here that the thermal conductivity can indeed be reduced by such a substitution, but that this substitution predominantly induces a reduction of the electronic part of the thermal conductivity and not of the lattice part. Interestingly, the magnonic contribution to S below TC disappears as x increases, while at high T, S tends to a very similar value (close to -42 µV K-1) for all the samples investigated. This article is part of a discussion meeting issue 'Energy materials for a low carbon future'.

11.
Chem Commun (Camb) ; 55(42): 5878-5881, 2019 May 21.
Artículo en Inglés | MEDLINE | ID: mdl-31045189

RESUMEN

Polycrystalline Sr2Fe1+xRe1-xO6 samples have been synthesized and structurally characterized by X-ray powder diffraction, transmission electron microscopy and X-ray absorption spectroscopy. Resistivity strongly increases with x, but a large and negative magnetoresistance persists up to x = 0.33. This is discussed considering the charge delocalization in iron and rhenium t2g orbitals.

12.
Ear Hear ; 40(3): 636-644, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30048253

RESUMEN

OBJECTIVES: It is well recognized that tinnitus can severely interfere with important aspects of life such as sleep, concentration abilities, social activities, and mood. However, the impact of tinnitus may vary greatly from one individual to another, with some being severely affected and others only experiencing a slight handicap. Information from participants' experiences with tinnitus could help explain such variability. The full experience of living with tinnitus from a patient's perspective has been under-investigated, especially in comparison with the large and extensive body of qualitative research on hearing loss. This study aims to contribute to fill this gap and assess participants' experience of living with tinnitus. DESIGN: As part of a larger mixed design study, this inquiry used qualitative analyses to investigate participant's experiences with tinnitus. Twenty-seven tinnitus participants of different ages, sexes, audiometric profiles, and tinnitus severities were invited to discuss their tinnitus through semistructured interviews and journal entries. The interviews took place 1 month after participants completed a 3-week trial period with tinnitus maskers. RESULTS: The findings were grouped into three main themes: participants' appraisal of their tinnitus, factors modulating tinnitus experience, and consequences of tinnitus. Regarding participants' appraisal of their tinnitus, a dissociation between the tinnitus sensation (pitch, loudness) and tinnitus experience (annoyance/distress) was reported. Factors modulating tinnitus experience were classified as environmental factors and individual-specific factors, which were further divided into soundscape and other environmental factors for the former and attentional focus, stress level, physical state, fatigue, and auditory effort for the latter. Consequences of tinnitus included distraction, disrupted mental health and mood, headaches, fatigue, sleep disturbances, hearing difficulties, disrupted social life, and frustration. CONCLUSIONS: Two of the main themes (participants' appraisal of their tinnitus and consequences of tinnitus) were consistent with findings from a few previous qualitative studies. Factors modulating tinnitus experience also emerged as a prominent theme. Indeed, participants described a plethora of factors that affected their experiences of tinnitus. On the basis of these findings, an attentional model is proposed to account for how these factors might modulate the effects of tinnitus.


Asunto(s)
Ambiente , Salud Mental , Sueño , Participación Social , Acúfeno/psicología , Adulto , Afecto , Anciano , Atención , Fatiga , Femenino , Humanos , Masculino , Persona de Mediana Edad , Distrés Psicológico , Investigación Cualitativa , Índice de Severidad de la Enfermedad , Acúfeno/fisiopatología
13.
JAMA Otolaryngol Head Neck Surg ; 144(12): 1136-1144, 2018 12 01.
Artículo en Inglés | MEDLINE | ID: mdl-30267085

RESUMEN

Importance: Current individualized sound therapies for tinnitus rely on tinnitus pitch assessment, which is commonly derived from the standard clinical 2-alternative forced-choice (2-AFC) approach driven by the examiner. However, this method is limited by lack of individual test-retest reliability and focuses on a single rather than multiple tinnitus frequencies. Objective: To assess individual test-retest reliability of the 2-AFC, with a single final frequency (and corresponding loudness), and the tinnitus likeness rating (TLR), with the participant exposed to the entire audible frequency spectrum, from which 3 dominant frequencies and corresponding loudness were extracted. Design, Setting, and Participants: In this case series, participants with tinnitus underwent testing twice with both methods at a 1-month interval by experienced clinicians from January 6 through March 17, 2017. Each clinician tested each patient only once at visit 1 or 2 in a university audiology training setting with standardized equipment and was blind to previous assessment. Participants with bilateral or unilateral chronic tinnitus for longer than 6 months, in good health, without total deafness in either ear, and without cerumen in the ear canal were recruited through advertisements (community and clinics) and word of mouth (volunteer sample). The audiologists were likewise participants in the planned comparison between TLR and 2-AFC in the test-retest measures. Main Outcomes and Measures: Test-retest concordance with 95% CIs for each method, calculated as the proportion of participants with the same final frequency between the 2 visits (2-AFC) or with at least 1 concordant dominant frequency (TLR) as well as loudness differences of no greater than 10 dB. Results: The study sample included 31 participants (55% men; mean [SD] age, 50.7 [13.7] years). For TLR, 26 of 31 participants had at least 1 concordant dominant frequency between the 2 visits (proportion, 0.84; 95% CI, 0.66-0.95), whereas for 2-AFC, 7 of 31 participants had a concordant final tinnitus pitch in either ear (proportion, 0.23; 95% CI, 0.10-0.41). Loudness reliability followed the same pattern, with more concordant loudness levels in the TLR (proportion, 0.73; 95% CI, 0.52-0.88) than in the 2-AFC (proportion, 0.40; 95% CI, 0.05-0.85). Mean time taken to complete the tests was less than 15 minutes, and general appreciation by participants with tinnitus and audiologists were overall similar for both. Conclusions and Relevance: Superior test-retest concordance can be demonstrated at the individual level using the several dominant frequencies extracted from the patient-centered TLR.


Asunto(s)
Percepción de la Altura Tonal , Acúfeno/fisiopatología , Acúfeno/terapia , Audiometría , Umbral Auditivo , Femenino , Humanos , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados , Resultado del Tratamiento
14.
Sci Rep ; 8(1): 9921, 2018 07 02.
Artículo en Inglés | MEDLINE | ID: mdl-29967340

RESUMEN

Sensitivity to sounds is one frequent symptom of a sport-related concussion, but its assessment rarely goes beyond a single question. Here we examined sensitivity to sounds using psychoacoustic and psychometric outcomes in athletes beyond the acute phase of injury. Fifty-eight college athletes with normal hearing who either had incurred one or more sport-related concussions (N = 28) or who had never suffered head injury (N = 30) participated. Results indicated that the Concussed group scored higher on the Hyperacusis questionnaire and displayed greater sensitivity to sounds in psychoacoustic tasks compared to the Control group. However, further analyses that separated the Concussed group in subgroups with Sound sensitivity symptom (N = 14) and Without sound sensitivity symptom (N = 14) revealed that athletes with the sound complaint were the ones responsible for the effect: Concussed athletes with self-reported sound sensitivity had lower Loudness Discomfort Thresholds (LDLs), higher Depression and Hyperacusis scores, and shifted loudness growth functions compared to the other subgroup. A simple mediation model disclosed that LDLs exert their influence both directly on Hyperacusis scores as well as indirectly via depressive symptoms. We thus report a new clinical presentation of hyperacusis and discuss possible mechanisms by which it could arise from concussion.


Asunto(s)
Atletas , Conmoción Encefálica/complicaciones , Hiperacusia/etiología , Depresión/etiología , Femenino , Humanos , Masculino , Pruebas Neuropsicológicas , Sonido , Deportes , Encuestas y Cuestionarios , Adulto Joven
15.
Hear Res ; 366: 90-98, 2018 09.
Artículo en Inglés | MEDLINE | ID: mdl-29692331

RESUMEN

A common method designed to identify if an animal hears tinnitus assumes that tinnitus "fills-in" silent gaps in background sound. This phenomenon has not been reliably demonstrated in humans. One test of the gap-filling hypothesis would be to determine if gap-evoked cortical potentials are absent or attenuated when measured within background sound matched to the tinnitus sensation. However the tinnitus sensation is usually of low intensity and of high frequency, and it is unknown if cortical responses can be measured with such "weak" stimulus properties. Therefore the aim of the present study was to test the plausibility of observing these responses in the EEG in humans without tinnitus. Twelve non-tinnitus participants heard narrowband noises centered at sound frequencies of 5 or 10 kHz at sensation levels of either 5, 15, or 30 dB. Silent gaps of 20 ms duration were randomly inserted into noise stimuli, and cortical potentials evoked by these gaps were measured by 64-channel EEG. Gap-evoked cortical responses were statistically identifiable in all conditions for all but one participant. Responses were not significantly different between noise frequencies or levels. Results suggest that cortical responses can be measured when evoked by gaps in sounds that mirror acoustic properties of tinnitus. This design can validate the animal model and be used as a tinnitus diagnosis test in humans.


Asunto(s)
Corteza Auditiva/fisiopatología , Acúfeno/diagnóstico , Estimulación Acústica/métodos , Adulto , Animales , Enfermedad Crónica , Electroencefalografía , Potenciales Evocados Auditivos/fisiología , Femenino , Voluntarios Sanos , Humanos , Masculino , Psicoacústica , Reflejo de Sobresalto/fisiología , Acúfeno/fisiopatología , Acúfeno/psicología , Adulto Joven
16.
Inorg Chem ; 56(15): 9209-9218, 2017 Aug 07.
Artículo en Inglés | MEDLINE | ID: mdl-28704050

RESUMEN

Single-crystal and polycrystalline Ba4Cu8Se13 were synthesized; the average crystal structure was solved by single-crystal X-ray diffraction, and the structural model was confirmed by a detailed electron microscopy study of polycrystalline Ba4Cu8Se13. The title compound can be rationalized as (Ba2+)4(Cu+)8(Se2-)2(Se22-)4(Se34-) and crystallizes in a new structure type (space group C2/c with a = 9.171(8) Å, b = 9.146(8) Å, c = 27.35(3) Å, ß = 93.21(3)°, and V = 2291 Å3). It contains unprecedented Cu4Se9 fragments with planar Cu rectangles. These fragments form two-dimensional layers via regular (2c-2e) Se-Se bonds. Two of these layers are then connected in the third dimension via linear, hypervalent Se34- units, resulting in "sandwichlike", layered building blocks, which are stacked along c and separated by Ba. Ba4Cu8Se13 is the first example where Se22- and Se34- groups coexist. We were able to visualize the crystal structure by recording HAADF images, which clearly reveal the Cu4Se9 fragments and linear Se34- units. The title compound is a charge-balanced semiconductor and possesses a large Seebeck coefficient (380 µV K-1 at 200 K) and a low thermal conductivity (0.77 W m-1 K-1 at 200 K)-two requirements for efficient thermoelectric materials.

17.
Front Neurol ; 8: 38, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28270792

RESUMEN

Current clinical assessment of tinnitus relies mainly on self-report. Psychoacoustic assessment of tinnitus pitch and loudness are recommended but methods yield variable results. Herein, we investigated the proposition that a previously validated fixed laboratory-based method (Touchscreen) and a newly developed clinically relevant portable prototype (Stand-alone) yield comparable results in the assessment of psychoacoustic tinnitus pitch and loudness. Participants with tinnitus [N = 15, 7 with normal hearing and 8 with hearing loss (HL)] and participants simulating tinnitus (simulators, N = 15) were instructed to rate the likeness of pure tones (250-16 kHz) to their tinnitus pitch and match their loudness using both methods presented in a counterbalanced order. Results indicate that simulators rated their "tinnitus" at lower frequencies and at louder levels (~10 dB) compared to tinnitus participants. Tinnitus subgroups (with vs. without HL) differed in their predominant tinnitus pitch (i.e., lower in the tinnitus with HL subgroups), but not in their loudness matching in decibel SL. Loudness at the predominant pitch was identified as a factor yielding significant sensitivity and specificity in discriminating between the two groups of participants. Importantly, despite differences in the devices' physical presentations, likeness and loudness ratings were globally consistent between the two methods and, moreover, highly reproducible from one method to the other in both groups. All in all, both methods yielded robust tinnitus data in less than 12 min, with the Stand-alone having the advantage of not being dependent of learning effects, being user-friendly, and being adapted to the audiogram of each patient to further reduce testing time.

18.
Sci Technol Adv Mater ; 18(1): 919-938, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-29383043

RESUMEN

The electronic transport properties of the delafossite oxides [Formula: see text] are usually understood in terms of two well-separated entities, namely the triangular [Formula: see text] and ([Formula: see text] layers. Here, we review several cases among this extensive family of materials where the transport depends on the interlayer coupling and displays unconventional properties. We review the doped thermoelectrics based on [Formula: see text] and [Formula: see text], which show a high-temperature recovery of Fermi-liquid transport exponents, as well as the highly anisotropic metals [Formula: see text], [Formula: see text], and [Formula: see text], where the sheer simplicity of the Fermi surface leads to unconventional transport. We present some of the theoretical tools that have been used to investigate these transport properties and review what can and cannot be learned from the extensive set of electronic structure calculations that have been performed.

19.
J Mater Chem C Mater ; 4(9): 1871-1880, 2016 Mar 07.
Artículo en Inglés | MEDLINE | ID: mdl-27774151

RESUMEN

A family of phases, Co x TiS2 (0 ≤ x ≤ 0.75) has been prepared and characterised by powder X-ray and neutron diffraction, electrical and thermal transport property measurements, thermal analysis and SQUID magnetometry. With increasing cobalt content, the structure evolves from a disordered arrangement of cobalt ions in octahedral sites located in the van der Waals' gap (x ≤ 0.2), through three different ordered vacancy phases, to a second disordered phase at x ≥ 0.67. Powder neutron diffraction reveals that both octahedral and tetrahedral inter-layer sites are occupied in Co0.67TiS2. Charge transfer from the cobalt guest to the TiS2 host affords a systematic tuning of the electrical and thermal transport properties. At low levels of cobalt intercalation (x < 0.1), the charge transfer increases the electrical conductivity sufficiently to offset the concomitant reduction in |S|. This, together with a reduction in the overall thermal conductivity leads to thermoelectric figures of merit that are 25% higher than that of TiS2, ZT reaching 0.30 at 573 K for Co x TiS2 with 0.04 ≤ x ≤ 0.08. Whilst the electrical conductivity is further increased at higher cobalt contents, the reduction in |S| is more marked due to the higher charge carrier concentration. Furthermore both the charge carrier and lattice contributions to the thermal conductivity are increased in the electrically conductive ordered-vacancy phases, with the result that the thermoelectric performance is significantly degraded. These results illustrate the competition between the effects of charge transfer from guest to host and the disorder generated when cobalt cations are incorporated in the inter-layer space.

20.
Dalton Trans ; 45(30): 12119-26, 2016 Jul 26.
Artículo en Inglés | MEDLINE | ID: mdl-27396273

RESUMEN

The structure of Ba0.5Cr5Se8 has been recently resolved, and its thermoelectric and magnetic properties have been studied. A ZT of 0.12 was found at around 800 K. Here, we report a study on the pseudo-hollandite BaxCr5Se8 solid-solution with 0.5 ≤ x ≤ 0.55 and its thermoelectric and magnetic properties. There is no significant impact either on the cell parameters depending on the cation content or on the magnetic properties. However, thermoelectric properties are radically changed depending on x content. While the low thermal conductivity, around 0.8 W m(-1) K(-1), remains similar for all samples, a respective increase and decrease of the resistivity and the Seebeck coefficient are observed with increasing Ba content. The maximum Seebeck coefficient is found with Ba0.5Cr5Se8 at around 635 K with 315 µV K(-1), and the Seebeck coefficient then decreases and is correlated with an activation of minority charge carriers confirmed by Hall measurements. A similar but steeper behavior is observed for the Ba0.55Cr5Se8 temperature dependence plot at around 573 K. Finally, the best thermoelectric performances are found using the lowest content of Ba, unlike when x tends to 0.55, ZT approaches a tenth of the initial best value. BaxCr5Se8 compounds are antiferromagnetic with TN = 58 K. A large peak in thermal conductivity is observed around the antiferromagnetic transition for all stoichiometry.

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