• MeSH
• acetabulum anatomie a histologie   fyziologie   patologie   MeSH
• analýza metodou konečných prvků * využití   MeSH
• anatomické modely MeSH
• biomechanika MeSH
• kyčelní kloub * fyziologie   patologie   MeSH
• kyčelní protézy využití   MeSH
• lidé MeSH
• mechanické jevy MeSH
• pánev anatomie a histologie   fyziologie   patologie   MeSH
• počítačová simulace využití   MeSH
• statistika jako téma MeSH
• teoretické modely * MeSH
• transplantáty transplantace   MeSH
• Check Tag
• lidé MeSH

• MeSH
• biologické modely MeSH
• biomechanika MeSH
• počítačová grafika MeSH
• počítačová simulace MeSH
• tkáně MeSH
• zobrazování trojrozměrné metody   MeSH

• MeSH
• biomechanika MeSH
• dítě MeSH
• kyčelní kloub patologie   terapie   MeSH
• lidé MeSH
• mechanický stres MeSH
• nemoci kloubů patologie   MeSH
• teoretické modely MeSH
• Check Tag
• dítě MeSH
• lidé MeSH

• MeSH
• analýza metodou konečných prvků * využití   MeSH
• anatomické modely * MeSH
• femur anatomie a histologie   MeSH
• kostra MeSH
• lebka * anatomie a histologie   fyziologie   MeSH
• lidé MeSH
• magnetická rezonanční tomografie metody   využití   MeSH
• mandibula anatomie a histologie   MeSH
• počítačová rentgenová tomografie využití   MeSH
• statistika jako téma MeSH
• teoretické modely MeSH
• Check Tag
• lidé MeSH

PURPOSE: Computational models of microwave ablation (MWA) are widely used during the design optimization of novel devices and are under consideration for patient-specific treatment planning. The objective of this study was to assess the sensitivity of computational models of MWA to tissue biophysical properties. METHODS: The Morris method was employed to assess the global sensitivity of the coupled electromagnetic-thermal model, which was implemented with the finite element method (FEM). The FEM model incorporated temperature dependencies of tissue physical properties. The variability of the model was studied using six different outputs to characterize the size and shape of the ablation zone, as well as impedance matching of the ablation antenna. Furthermore, the sensitivity results were statistically analyzed and absolute influence of each input parameter was quantified. A framework for systematically incorporating model uncertainties for treatment planning was suggested. RESULTS: A total of 1221 simulations, incorporating 111 randomly sampled starting points, were performed. Tissue dielectric parameters, specifically relative permittivity, effective conductivity, and the threshold temperature at which they transitioned to lower values (i.e., signifying desiccation), were identified as the most influential parameters for the shape of the ablation zone and antenna impedance matching. Of the thermal parameters considered in this study, the nominal blood perfusion rate and the temperature interval across which the tissue changes phase were identified as the most influential. The latent heat of tissue water vaporization and the volumetric heat capacity of the vaporized tissue were recognized as the least influential parameters. Based on the evaluation of absolute changes, the most important parameter (perfusion) had approximately 40.23 times greater influence on ablation area than the least important parameter (volumetric heat capacity of vaporized tissue). Another significant input parameter (permittivity) had 22.26 times higher influence on the deviation of ablation edge shape from a sphere than one of the less important parameters (latent heat of liver tissue vaporization). CONCLUSIONS: Dielectric parameters, blood perfusion rate, and the temperature interval across which the tissue changes phase were found to have the most significant impact on MWA model outputs. The latent heat of tissue water vaporization and the volumetric heat capacity of the vaporized tissue were recognized as the least influential parameters. Uncertainties in model outputs identified in this study can be incorporated to provide probabilistic maps of expected ablation outcome for patient-specific treatment planning.

• MeSH
• ablace metody   MeSH
• algoritmy MeSH
• analýza metodou konečných prvků MeSH
• biomechanika MeSH
• elektromagnetické jevy MeSH
• individualizovaná medicína metody   MeSH
• játra fyziologie   MeSH
• lidé MeSH
• mikrovlny * MeSH
• počítačová simulace * MeSH
• regionální krevní průtok MeSH
• teoretické modely * MeSH
• teplota MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

• MeSH
• analýza metodou konečných prvků * využití   MeSH
• anatomické modely MeSH
• biomechanika MeSH
• kyčelní kloub * fyziologie   patologie   MeSH
• lidé MeSH
• mechanický stres * MeSH
• osteoartróza diagnóza   patologie   MeSH
• počítačové zpracování obrazu MeSH
• radiografie využití   MeSH
• software MeSH
• statistika jako téma MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• práce podpořená grantem MeSH

Phonation into a glass tube is a voice training and therapy method that leads to beneficial effects in voice production. It has not been known, however, what changes occur in the vocal tract during and after the phonation into a tube. This pilot study examined the vocal tract shape in a female subject before, during, and after phonation into a tube using computer tomography (CT). Three-dimensional finite-element models (FEMs) of the vocal tract were derived from the CT images and used to study changes in vocal tract input impedance. When phonating on vowel [a:] the data showed tightened velopharyngeal closure and enlarged cross-sectional areas of the oropharyngeal and oral cavities during and after the tube-phonation. FEM calculations revealed an increased input inertance of the vocal tract and an increased acoustic energy radiated out of the vocal tract after the tube-phonation. The results indicate that the phonation into a tube causes changes in the vocal tract which remain also when the tube is removed. These effects may help improving voice production in patients and voice professionals.

• MeSH
• akustika řeči MeSH
• analýza metodou konečných prvků MeSH
• biologické modely MeSH
• fonace MeSH
• hlasové řasy fyziologie   radiografie   MeSH
• kvalita hlasu MeSH
• larynx fyziologie   radiografie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• pilotní projekty MeSH
• počítačová rentgenová tomografie MeSH
• rentgenový obraz - interpretace počítačová MeSH
• zobrazování trojrozměrné MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• analýza metodou konečných prvků MeSH
• biosenzitivní techniky přístrojové vybavení   MeSH
• časná diagnóza MeSH
• kardiografie impedanční * metody   přístrojové vybavení   MeSH
• lidé MeSH
• modely kardiovaskulární MeSH
• pleurální výpotek * diagnóza   patofyziologie   MeSH
• plicní edém * diagnóza   patofyziologie   MeSH
• počítačová simulace MeSH
• pulzatilní průtok MeSH
• srdeční selhání * diagnóza   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• práce podpořená grantem MeSH

The accuracy, feasibility and sensitivity of several different methods for calculating muscle forces during functional activities in humans were investigated. The upper extremity dynamic system was chosen, where the flexion-extension of elbow joint was studied. To counteract the redundant mechanisms we adopted optimization criteria with and without models of individual muscles according to their active and passive properties. Comparisons with known movements solved by inverse dynamics approach and optimization techniques provided similar results for all optimization criteria. Moreover, if muscle models with active and passive properties are included in these analyses, it is relatively easy to calculate muscle forces of both agonists and antagonists. These approaches may be used to provide input data for dynamic FEM stress analysis of bones and bone-implant systems.

• MeSH
• biologické modely MeSH
• financování organizované MeSH
• kosterní svaly fyziologie   MeSH
• lidé MeSH
• loketní kloub fyziologie   MeSH
• mechanický stres MeSH
• počítačová simulace MeSH
• posturální rovnováha fyziologie   MeSH
• pružnost MeSH
• šlachy fyziologie   MeSH
• svalová kontrakce fyziologie   MeSH
• Check Tag
• lidé MeSH

Microfabricated electroacoustic transducers with perforated moving plates used as microphones or acoustic sources have appeared in the literature in recent years. However, optimization of the parameters of such transducers for use in the audio frequency range requires high-precision theoretical modeling. The main objective of the paper is to provide such an analytical model of a miniature transducer with a moving electrode in the form of a perforated plate (rigid elastically supported or elastic clamped at all boundaries) loaded by an air gap surrounded by a small cavity. The formulation for the acoustic pressure field inside the air gap enables expression of the coupling of this field to the displacement field of the moving plate and to the incident acoustic pressure through the holes in the plate. The damping effects of the thermal and viscous boundary layers originating inside the air gap, the cavity, and the holes in the moving plate are also taken into account. The analytical results, namely, the acoustic pressure sensitivity of the transducer used as a microphone, are presented and compared to the numerical (FEM) results.

• Publikační typ
• časopisecké články MeSH