A study was performed to find and test quantitative methods of analysing echographic signals for the differentiation of diffuse liver diseases. An on-line data acquisition system was used to acquire radiofrequency (RF) echo signals from volunteers and patients. Several methods to estimate the frequency-dependent attenuation coefficient were evaluated, in which a correction for the frequency and depth-dependent diffraction and focusing effects caused by the sound beam was applied. Using the estimated value of the attenuation coefficient the RF signals themselves were corrected to remove the depth dependencies caused by the sound beam and by the frequency-dependent attenuation. After this preprocessing the envelope of the corrected RF signals was calculated and B-mode images were reconstructed. The texture was analysed in the axial direction by first- and second-order statistical methods. The accuracy and precision of the attenuation methods were assessed by using computer simulated RF signals and RF data obtained from a tissue-mimicking phantom. The phantom measurements were also used to test the performance of the methods to correct for the depth dependencies. The echograms of 163 persons, both volunteers and patients suffering from a diffuse liver disease (cirrhosis, hepatitis, haemochromatosis), were recorded. The mutual correlations between the estimated parameters were used to preselect parameters contributing independent information, and which can subsequently be used in a discriminant analysis to differentiate between the various diseased conditions.
Nowadays lighting criterions for internal spaces can be widened; because there is need to not only stimulate properly the human visual system but also to entrain the non-visual system of users or inhabitants. Since the medical discoveries in the field of light influence of circadian system, a system that controls our daily body rhythms, gave us basic principles how it works, we can use advanced methods how to evaluate internal light climate in the buildings. We focused on the colours of wall finishes, which influence the spectral composition of the light that enters the eye of inhabitants in specified locations. A set of specified applied colors were compared to the neutrally coloured walls. Also the effect of external shading obstruction was examined in this study. This observation, based on the spectral examination of light conditions, may provide more complex overview on selection of internal surfaces colours in long-term occupied spaces, taking health and wellbeing into consideration.
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