Absorption and reduced scattering coefficient estimation in pigmented human skin tissue by experimental colorimetric fitting.

This study aims to estimate the optical properties, absorption (µ a), and reduced scattering (µ s ') coefficients of ex vivo human skin through the individual typology angle (ITA) by only using the skin color parameters. Human skin samples were grouped according to their ITA value and measured using a colorimeter for validation. An integrating sphere and the inverse adding-doubling algorithm were applied to compute the samples µ a and µ s '. The µ a increases as the ITA decreases. An axis swap was performed to generate the µ a versus the ITA for all wavelengths between 500 nm and 800 nm with a spectral resolution of 10 nm. Linearization was performed and a correlation was found. An equation to fit µ a based solely on the ITA values was estimated. The µ s ' does not change with ITA, but it could be fit with an inverse power law as a function of the wavelength. Both equations have a coefficient of determination (R 2) higher than 0.93, indicating a good agreement with our model. An experimental model to estimate the absorption and reduced scattering coefficients of ex vivo human skin through ITA was found. The model has high agreement with the experimental data, with an R 2 between 0.932 and 0.997, and these findings may be relevant for photobiomodulation and light treatment applications to estimate the effect of the melanin on the therapy.

Analysis of the accuracy and reliability of vertical jump evaluation using a low-cost acquisition system.

BACKGROUND: The vertical jump can be analyzed based on the flight time achieved by the individual. This measurement can be obtained using a force platform or a three-dimensional infrared camera system, but such equipment is expensive and requires training for data collection and processing. Thus, this study aimed to evaluate the accuracy and reliability of using a smartphone and the Kinovea software compared with a force platform as a method of vertical jump analysis. METHODS: For this purpose, two independent evaluators analyzed videos of bipodal and unipodal vertical jumps by counting the variables among participants. The participants performed three consecutive jumps in bipodal and unipodal conditions with the dominant and non-dominant legs. RESULTS: The intra-rater analysis for bipodal jumps was found to have excellent reproducibility (ICC = 0.903 to 0.934), whereas for unipodal jumps, the reproducibility was moderate to excellent (ICC = 0.713 to 0.902). The inter-rater analysis showed that for bipodal jumps, the reproducibility is substantial to excellent (ICC = 0.823 to 0.926), while for unipodal jumps, it is moderate (ICC = 0.554 to 0.702). CONCLUSIONS: Therefore, it can be concluded that the vertical jump evaluation can be performed using the smartphone-Kinovea system. However, the same evaluator should carry out the evaluation to maintain reliable indices.