Vibrotactile Thresholds on the Wrist for Vibrations Normal to the Skin.

In order to facilitate the development of wrist-worn vibrotactile devices, detailed knowledge about how vibrations are perceived by the users is needed. In particular, perceptual thresholds in amplitude are really important. Thresholds have been measured in the literature for other areas of the body, but given the variability reported between areas (shape of the threshold curve, position of maximum sensitivity), thresholds on the wrist can not be inferred from previous measurements and must be measured. The amplitude thresholds for vibrations normal to the skin surface were evaluated on 28 participants, with a three interval forced choice method. They were measured for 7 frequencies that are classical in the literature about vibrotactile perception (25, 40, 80, 160, 250, 320, and 640 Hz). The classical U-shape of the amplitude-threshold curve is observed, with a maximum sensitivity at around 160 Hz, which differs from other body areas, but confirms recent results obtained for vibrations parallel to the skin surface of the same body area. The sensitivity thresholds of vibrotactile signals appear to be in the micrometer range.

Influence of the player on the dynamics of the electric guitar.

The sound of the electric guitar is strongly dependent on the string vibration. Where a mode of the structure coincides with a mode of the fretted string, coupling between the string and structure occurs at that "deadspot." The coupling significantly lowers decay time, leading to the name [Paté, Le Carrou, and Fabre (2014). J. Acoust. Soc. Am. 135(5), 3045-3055]. But how the guitarist affects the dynamic behavior of the structure by grasping the neck, holding the instrument with the strap, or laying the instrument on his/her thigh remains to be investigated. This is the aim of the paper. Two methods are proposed to identify the modal parameters of the electric guitar structure, either by a classical modal analysis in simulated playing configuration, or by an operational modal analysis in real playing configuration. For this latter method, modal parameters are identified from dynamic measurements performed when each string is plucked. Both methods are compared and allow one to quantify the modal frequency modification and the added modal damping, which depend on the player's body-part in contact with the structure and on the modal shape considered. Consequences of these modal parameters on the modeled sound show that the player can increase the decay time close to a deadspot.

Estimation of salt intake in the Brazilian population: results from the 2013 National Health Survey. / Estimativa do consumo de sal pela população brasileira: resultado da Pesquisa Nacional de Saúde 2013.

OBJECTIVE: To estimate the salt intake in the Brazilian population according to their urinary sodium excretion. METHODS: The National Health Survey (2013) aimed to gather data on the health of adults (≥ 18 years) through a random selection of households. In each household, one adult was selected to have their biological data collected (anthropometry, blood pressure, and blood and urine tests). The urine sample was sent to a central laboratory to determine sodium (ion-selective electrode) and creatinine (Jaffé method) concentrations. Sodium excretion was estimated with the Tanaka equation. RESULTS: Urinary sodium and creatinine concentrations were measured in 8,083individuals (58% women). The mean salt intake was estimated at 9.34 g/day (95% confidence interval - 95%CI 9.27 - 9.41) and was higher in males (9.63 g/day; 95%CI 9.52 - 9.74) than in females (9.08 g/day; 95%CI 8.99 - 9.17). Wefound no significant differences regarding age group, ethnicity, or schooling. Salt intake was higher in the Southeast and South regions and lower in the Northeast and North. Only 2.4% (95%CI 2.0 - 2.8) of the sample consumed less than 5 g/day, and 58.2% (95%CI 56.7 - 59.6) of participants had an estimated intake of 8 to 12 g/day. CONCLUSION: The mean salt intake in the Brazilian population is approximately twice the recommended by the World Health Organization (5g/day).Given the association of high salt intake with hypertension and decreased renal function, these data indicate the need to adopt comprehensive public policies to reduce the consumption in the Brazilian population.

OBJETIVO: Estimar o consumo de sal na população brasileira pela excreção urinária de sódio. MÉTODOS: A Pesquisa Nacional de Saúde (2013) teve como objetivo obter dados de saúde de adultos (≥ 18 anos) por meio de seleção aleatória de domicílios. Em cada domicílio foi selecionado um adulto para coleta de dados biológicos (antropometria, pressão arterial, sangue e urina). A urina foi enviada para um laboratório central, para medida da concentração de sódio (eletrodo sensível) e creatinina (método de Jaffé). A estimativa da excreção de sódio foi feita com a equação de Tanaka. RESULTADOS: A dosagem urinária de sódio e de creatinina foi obtida em 8.083 indivíduos (58% mulheres). O consumo médio de sal foi estimado em 9,34 g/dia (intervalo de confiança de 95% - IC95% 9,27 - 9,41), sendo maior em homens (9,63 g/dia; IC95% 9,52 - 9,74) do que em mulheres (9,08 g/dia; IC95% 8,99 - 9,17). Não foram observadas diferenças importantes em relação à faixa etária, cor da pele nem escolaridade. O maior consumo foi detectado nas regiões Sudeste e Sul e o menor no Nordeste e Norte. Apenas 2,4% (IC95% 2,0 - 2,8) da amostra apresentou consumo inferior a 5 g/dia, e 58,2% (IC95% 56,7 - 59,6) dos participantes tiveram consumo estimado de 8 a 12 g/dia. CONCLUSÃO: O consumo médio de sal da população brasileira é, aproximadamente, o dobro da recomendação da Organização Mundial da Saúde (5g/dia). Tendo em vista a associação da alta ingestão de sal com hipertensão arterial e decréscimo da função renal, os dados apontam para a necessidade de adoção de políticas públicas abrangentes para redução desse consumo na população brasileira.

Estimativa do consumo de sal pela população brasileira: resultado da Pesquisa Nacional de Saúde 2013 / Estimation of salt intake in the Brazilian population: results from the 2013 National Health Survey

RESUMO: Objetivo: Estimar o consumo de sal na população brasileira pela excreção urinária de sódio. Métodos: A Pesquisa Nacional de Saúde (2013) teve como objetivo obter dados de saúde de adultos (≥ 18 anos) por meio de seleção aleatória de domicílios. Em cada domicílio foi selecionado um adulto para coleta de dados biológicos (antropometria, pressão arterial, sangue e urina). A urina foi enviada para um laboratório central, para medida da concentração de sódio (eletrodo sensível) e creatinina (método de Jaffé). A estimativa da excreção de sódio foi feita com a equação de Tanaka. Resultados: A dosagem urinária de sódio e de creatinina foi obtida em 8.083 indivíduos (58% mulheres). O consumo médio de sal foi estimado em 9,34 g/dia (intervalo de confiança de 95% - IC95% 9,27 - 9,41), sendo maior em homens (9,63 g/dia; IC95% 9,52 - 9,74) do que em mulheres (9,08 g/dia; IC95% 8,99 - 9,17). Não foram observadas diferenças importantes em relação à faixa etária, cor da pele nem escolaridade. O maior consumo foi detectado nas regiões Sudeste e Sul e o menor no Nordeste e Norte. Apenas 2,4% (IC95% 2,0 - 2,8) da amostra apresentou consumo inferior a 5 g/dia, e 58,2% (IC95% 56,7 - 59,6) dos participantes tiveram consumo estimado de 8 a 12 g/dia. Conclusão: O consumo médio de sal da população brasileira é, aproximadamente, o dobro da recomendação da Organização Mundial da Saúde (5g/dia). Tendo em vista a associação da alta ingestão de sal com hipertensão arterial e decréscimo da função renal, os dados apontam para a necessidade de adoção de políticas públicas abrangentes para redução desse consumo na população brasileira.

ABSTRACT: Objective: To estimate the salt intake in the Brazilian population according to their urinary sodium excretion. Methods: The National Health Survey (2013) aimed to gather data on the health of adults (≥ 18 years) through a random selection of households. In each household, one adult was selected to have their biological data collected (anthropometry, blood pressure, and blood and urine tests). The urine sample was sent to a central laboratory to determine sodium (ion-selective electrode) and creatinine (Jaffé method) concentrations. Sodium excretion was estimated with the Tanaka equation. Results: Urinary sodium and creatinine concentrations were measured in 8,083individuals (58% women). The mean salt intake was estimated at 9.34 g/day (95% confidence interval - 95%CI 9.27 - 9.41) and was higher in males (9.63 g/day; 95%CI 9.52 - 9.74) than in females (9.08 g/day; 95%CI 8.99 - 9.17). Wefound no significant differences regarding age group, ethnicity, or schooling. Salt intake was higher in the Southeast and South regions and lower in the Northeast and North. Only 2.4% (95%CI 2.0 - 2.8) of the sample consumed less than 5 g/day, and 58.2% (95%CI 56.7 - 59.6) of participants had an estimated intake of 8 to 12 g/day. Conclusion: The mean salt intake in the Brazilian population is approximately twice the recommended by the World Health Organization (5g/day).Given the association of high salt intake with hypertension and decreased renal function, these data indicate the need to adopt comprehensive public policies to reduce the consumption in the Brazilian population.

Machine learning reveals cyclic changes in seismic source spectra in Geysers geothermal field.

The earthquake rupture process comprises complex interactions of stress, fracture, and frictional properties. New machine learning methods demonstrate great potential to reveal patterns in time-dependent spectral properties of seismic signals and enable identification of changes in faulting processes. Clustering of 46,000 earthquakes of 0.3 < ML < 1.5 from the Geysers geothermal field (CA) yields groupings that have no reservoir-scale spatial patterns but clear temporal patterns. Events with similar spectral properties repeat on annual cycles within each cluster and track changes in the water injection rates into the Geysers reservoir, indicating that changes in acoustic properties and faulting processes accompany changes in thermomechanical state. The methods open new means to identify and characterize subtle changes in seismic source properties, with applications to tectonic and geothermal seismicity.

Auditory display of seismic data: On the use of experts' categorizations and verbal descriptions as heuristics for geoscience.

Auditory display can complement visual representations in order to better interpret scientific data. A previous article showed that the free categorization of "audified seismic signals" operated by listeners can be explained by various geophysical parameters. The present article confirms this result and shows that cognitive representations of listeners can be used as heuristics for the characterization of seismic signals. Free sorting tests are conducted with audified seismic signals, with the earthquake/seismometer relative location, playback audification speed, and earthquake magnitude as controlled variables. The analysis is built on partitions (categories) and verbal comments (categorization criteria). Participants from different backgrounds (acousticians or geoscientists) are contrasted in order to investigate the role of the participants' expertise. Sounds resulting from different earthquake/station distances or azimuths, crustal structure and topography along the path of the seismic wave, earthquake magnitude, are found to (a) be sorted into different categories, (b) elicit different verbal descriptions mainly focused on the perceived number of events, frequency content, and background noise level. Building on these perceptual results, acoustic descriptors are computed and geophysical interpretations are proposed in order to match the verbal descriptions. Another result is the robustness of the categories with respect to the audification speed factor.

Influence of plectrum shape and jack velocity on the sound of the harpsichord: An experimental study.

A controversial discussion in the musical community regards the ability of the harpsichord to produce sound level or timbre changes. The jack velocity (controlled in real time within a musical context) and the plectrum shape (modified by the musician or maker prior to the performance) appear to be the two control parameters at the disposal of the harpsichord makers and players for shaping the sound. This article initiates the acoustical study of the control parameters of the harpsichord, presenting a framework for the investigation of these two parameters with means of experimental mechanics measurement. A robotic finger is used for producing repeatable plucks with various jack velocities and plectrum shapes. The plectrum bending, vibrating string's initial conditions, and radiated sound are recorded and analysed. First, results are obtained from measurements carried out on one string, for four plectrum shapes and four jack velocities. The plectrum shape has been found to have an influence on its bending behavior when interacting with the string; on the string's initial conditions (position and velocity); and on the resulting sound (sound level, spectral centroid, and decay time). The jack velocity does not have an influence on any of the measured quantities.

Predicting the decay time of solid body electric guitar tones.

Although it can be transformed by various electronic devices, the sound of the solid body electric guitar originates from, and is strongly linked with, the string vibration. The coupling of the string with the guitar alters its vibration and can lead to decay time inhomogeneities. This paper implements and justifies a framework for the study of decay times of electric guitar tones. Two damping mechanisms are theoretically and experimentally identified: the string intrinsic damping and the damping due to mechanical coupling with the neck of the guitar. The electromagnetic pickup is shown to not provide any additional damping to the string. The pickup is also shown to be far more sensitive to the out-of-plane polarization of the string. Finally, an accurate prediction of the decay time of electric guitar tones is made possible, whose only requirements are the knowledge of the isolated string dampings and the out-of-plane conductance at the neck of the guitar. This prediction can be of great help for instrument makers and manufacturers.