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Enhanced biomechanical characteristics of connective tissues and development of artificial implants
Varga, Ferdinand ; Amler, Evžen (advisor) ; Rosina, Jozef (referee) ; Daniel, Matej (referee) ; Sabo, Ján (referee)
(english) Hyaline cartilages are designed to enable smooth life-long articular move- ment. They serve also substantial role in load bearing, being loaded especially in normal compression. Eventual deterioration of articular cartilage tissue therefore has crucial consequences for affected individ- ual. Characterization of native articular cartilage and application of gained knowledge in reconstructive cartilage treatment is therefore de- sired. Mechanical characteristics are of prime importance. Blunt impact testing method in pendulum setup was developed to characterize cartilage tissue under physiological values of dynamic com- pressive loading. Information on impact process was simultaneously read by piezoelectric accelerometer and laser doppler vibrometer. Acquired data were processed to form loading diagrams and to evaluate standard mechanical quantities. The method was found to be consistent, reliable and effective way of mechanical characterization. Introduced technique was used for qualitative and quantitative de- scription of native articular cartilage, correlation of its condition with mechanical properties, assessment of tissue engineered materials quality and approval of newly designed artificial materials suitability. Consider- ing native cartilage status, dissipated energy was found to be...
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Identifikace aktivity štítné žlázy a pravděpodobnostní odhadování absorbovaných dávek v nukleární medicíně
Jirsa, Ladislav ; Quinn, A. ; Varga, F.
The Bayesian identification of a linear regression model (called the biphasic model) for time dependence of thyroid gland activity in 131I radiotherapy is presented. Prior knowledge is elicited via hard parameter constraints and via the merging of external information from an archive of patient records. This prior regularization is shown to be crucial in the reported context, where data typically comprise only two or three high-noise measurements. The posterior distribution is simulated via a Langevin diffusion algorithm, whose optimization for the thyroid activity application is explained. Excellent patient-specific predictions of thyroid activity are reported. The posterior inference of the patient-specific total radiation dose is computed, allowing the uncertainty of the dose to be quantified in a consistent form. The relevance of this work in clinical practice is explained.
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