Brno University of Technology

About: Brno University of Technology is a education organization based out in Brno, Czechia. It is known for research contribution in the topics: Computer science & Fracture mechanics. The organization has 6339 authors who have published 15226 publications receiving 194088 citations. The organization is also known as: Vysoké učení technické v Brně & BUT.

Transparent Tetragonal Yttria-Stabilized Zirconia Ceramics: Influence of Scattering Caused by Birefringence

Abstract: The correlation between grain size, optical birefringence, and transparency is discussed for tetragonal zirconia (ZrO2) ceramics using the Mie, Rayleigh, and Rayleigh–Gans–Debye scattering models. Our results demonstrate that at the degree of mean birefringence in the range (0.03–0.04) expected for tetragonal ZrO2, only the Mie theory provides reasonable results. At small particle size (o50 nm) the more straightforward Rayleigh approximation correlates with the Mie model. A real in-line transmission of B50% at visible light and 1 mm thickness is expected at a mean grain size o40 nm and B70% at a mean grain size o20 nm. At an infrared (IR) wavelength of 5 lm there should not be any scattering caused by birefringence for grain sizes o200 nm. Our simulations were validated with experimental data for tetragonal ZrO2 (3 mol% Y2O3) ceramics made from a powder with an initial particle size of B10 nm by sintering in air and using hot-isostatic pressing. The maximum in-line transmission of about 77% was observed at IR wavelengths of 3–5 lm.

Speech disorders in Parkinson's disease: early diagnostics and effects of medication and brain stimulation.

Abstract: Hypokinetic dysarthria (HD) occurs in 90% of Parkinson’s disease (PD) patients. It manifests specifically in the areas of articulation, phonation, prosody, speech fluency, and faciokinesis. We aimed to systematically review papers on HD in PD with a special focus on (1) early PD diagnosis and monitoring of the disease progression using acoustic voice and speech analysis, and (2) functional imaging studies exploring neural correlates of HD in PD, and (3) clinical studies using acoustic analysis to evaluate effects of dopaminergic medication and brain stimulation. A systematic literature search of articles written in English before March 2016 was conducted in the Web of Science, PubMed, SpringerLink, and IEEE Xplore databases using and combining specific relevant keywords. Articles were categorized into three groups: (1) articles focused on neural correlates of HD in PD using functional imaging (n = 13); (2) articles dealing with the acoustic analysis of HD in PD (n = 52); and (3) articles concerning specifically dopaminergic and brain stimulation-related effects as assessed by acoustic analysis (n = 31); the groups were then reviewed. We identified 14 combinations of speech tasks and acoustic features that can be recommended for use in describing the main features of HD in PD. While only a few acoustic parameters correlate with limb motor symptoms and can be partially relieved by dopaminergic medication, HD in PD seems to be mainly related to non-dopaminergic deficits and associated particularly with non-motor symptoms. Future studies should combine non-invasive brain stimulation with voice behavior approaches to achieve the best treatment effects by enhancing auditory-motor integration.