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The constants a and b of the Van der Waals state equation for atmosphere are determined from the concentration, critical temperature and critical pressure of the air components, using the Kay mixing rule. The radiosonde measures atmospheric pressure p, temperature T and other meteorological variables at various altitude levels. Therefore, the density of the atmosphere can be calculated based on the parameters a, b, p and T. In this study, the diurnal and nocturnal vertical profiles of the monthly average density, in the atmosphere of metropolitan region of Natal-RN, Brazil, from 2010 to 2017, were constructed considering the atmospheric system as an ideal gas and as a Van der Waals gas. The vertical profiles of the mean density difference between these two approaches and the temperature were also shown. In both scenarios, the radiosonde data of the atmosphere of this region for the calculation of the density were used, with the altitude ranging from 50m to 10km, interpolated every 10m. It has verified that the density of the atmosphere as a Van der Waals gas presents values higher than the density of air as an ideal gas at low altitudes. In both cases, densities tend therefore to have the same values when altitude increases. It has also showed a strong dependence on density related to temperature, such that the densities presented higher values in the colder months. [ABSTRACT FROM AUTHOR]

Purpose: to define aerodynamic measures in Brazilian Portuguese speakers without voice complaints, obtained by the EVA program. Method: the study included 20 men and 20 women who had their voices analyzed. Results: the mean values with subglottic pressure for female and male voices were: Subglottic pressure = 5.84 hPa and 6.7 hPa; average intensity = 79.21dB and 81.7dB; oral mean flow = 0.09 dm3/s and 0.16 dm3/s; glottic efficiency = 13.87dB/hPa and 12.78 dB/hPa; laryngeal efficiency = 188.08 dB/(hPa.dm3/s) and 97.11dB/(hPa.dm3/s); laryngeal resistance = 96.26 hPa/(dm3/s) and 52.64 hPa/(dm3/s); mean fundamental frequency (F0) = 208.28 Hz and 136.56 Hz and peak mouth pressure flow = 0.093 and 0.098. There was a statistically significant difference in relation to gender for the measures of average intensity, efficiency, larynx, laryngeal resistance and mean fundamental frequency. The average flow for the oral female and male voices were: subglottic pressure = 6.05 hPa and 6.6 hPa; average intensity = 65.50 dB and 66.3 dB; oral mean flow = 0, 10 dm3/s and 0.13 dm3/s; glottic efficiency = 11.12 dB/hPa and 11.77 dB/hPa; laryngeal efficiency = 144.83 dB/( hPa.dm3/s) and 97.89 dB/( hPa.dm3/s); laryngeal resistance = 78.98 hPa/(dm3/s) and 61.81 hPa/( dm3/s); average F0 = 222.52 Hz and 139.20 Hz and peak pressure oral flow = 0.047 and 0.053. Conclusion: EVA is a new program in Brazil, and analysing the aerodynamic measures in Brazilian Portuguese speakers, allows us to obtain reference values, thus allowing comparisons with future studies. [ABSTRACT FROM AUTHOR]