Mechanické vlastnosti mnohých biologických materiálů odpovídají vlastnostem tzv. viskoelastických těles. Do kategorie viskoelastických těles lze zařadit například kůží, cévní stěny, mnohé struktury vnitřních orgánů a četné další biologické materiály. Mechanické vlastnosti biologických materiálů závisí na věku a na zdravotním stavu organismu a lze tedy očekávat jejich využití jako indikátoru funkčního (biologického) věku organismu i jako diagnostického prostředku v medicíně. Metodika popisu a kvantifikace mechanických vlastností viskoelastických materiálů je známa z reologie. Primárním zdrojem informací jsou reologické charakteristiky, nejčastěfi křivky toku. Na základě těchto charakteristik se pak vytvářefi odpovídající reologické modely. Domníváme se, že využiti aparátů, který poskytaje kybernetika a zvláště teorie regulace, může významně přispět k rozvoji metodiky identifikace a určování parametrů reologickcých modelů. V této práci je shrnuta metodika identifikace diferenciaíních rovnic odpovídacích experimentálně zjištěným křivkám toku a metodika určování stiruktury a výpočtu parametrů odpovídajících reologických modelů. Jejich základem je teorie systémů a teorie identifikace kybernetických soustav.

Mechanical properties of many biological materials correspond to the properties of so called visco-elastic body. These materials can not be categorized simply as solids or as liquids. Skin, cell walls, numerous structures of internal organs and many other biological materials belong to this category. The mechanical properties of biological materials depend on age and health status of organism. They may be potentially used as indicators of functional age or as diagnostic tools. The methodology of description and quantification of mechanical properties of visco-elastic materials follows from rheology. The primary source of information on mechanical behavior are rheological characteristics, usually creep curves. According to the analysis if creep curves, rheological models of biological materials may be developed. We believe that cybernetic methods may significantly improve the currently used methodology of identification and parameters estimation of rheological models. The methodology of identification of differential equaions corresponding to experimentally obtained creep mrves is presented in the paper. Further, the method of estimation of structure and parameters of rheological models of biological materials is presented. The methodology is based on cybernetics and system theory.

• MeSH
• Biocompatible Materials MeSH
• Models, Biological MeSH
• Humans MeSH
• Linear Models MeSH
• Rheology MeSH
• Check Tag
• Humans MeSH

Mnohé materiály používané ve farmaceutické praxi a také mnohé biologické materiály stojí svými mechanickými vlastnostmi mezi pevnými pružnými tělesy a kapalinami. Tyto materiály nazýváme viskoelastické látky. Pro popis mechanických vlastností viskoelastických materiálů nevystačíme s metodikami, které poskytuje klasická teorie pružnosti a pevnosti či hydromechanika, a používáme obecnějšího aparátu, který vychází z reologie. Jako charakteristiky obsahující informace o mechanickém chování viskoelastických těles se v reologii nejčastěji používají křivky toku. Křivky toku poskytují bezprostředně informace o mechanických vlastnostech studovaných materiálů, pro podrobnější analýzu je třeba nalézt vhodný reologický model a určit jeho parametry. Běžně používané metody identifikace a odhadu pareimetrů reologických modelů nejsou dostatečně obecné a nevyužívají plně informací, které lze z křivek toku získat. Obecnou a plně propracovanou metodiku poskytuje teorie identifikace systémů. Spolu s využitím matematického aparátu, vycházejícího z Laplaceovy transformace, lze odvodit relativně jednoduchou a prakticky aplikovatelnou metodiku, umožňující plně využít informace, které obsahují křivky toku. Tato práce obsahuje v prvních dvou kapitolách analýzu současného stavu v oblasti vytváření reologických modelů. Hlavním přínosem práce je přehled teoretického aparátu po identifikaci a výpočet prvků modelů reologických systémů včetně příkladu, na němž je demonstrována praktická aplikace metodiky. V závěru je uveden obecný návod praktického postupu.

The methodology of description and quantification of mechanical properties of visco-elastic materials is particularly important for drug production as well as for pharmaceutical applications. Of similar importance is this methodology for biomechanics and other biological disciplines, as many biological materials belong to the category of visco-elastic bodies. Methods derived from the theory of elastic bodies or hydrodynamics are not adequate for the quantification of mechanical properties of these materials. Application of more general rheological methods is necessary in these cases. In rheology, the so-called creep curves are most frequently used as a source of information on the mechanical behavior of visco-elastic materials. Further, for more exact analysis, rheological models are often derived from the creep curves. Classical methods of identification and parameter estimation of rheological models are not sufficiently general and do not derive all information involved in creep curves. A significant contribution is the application of the general theory of systems, theory of system identification, and mathematical methodology of Laplace transformation to this field. Practical application of these methods is often relatively simple. The paper presents the necessary theoretical background and a practical guide for utilization of this methodology.

• MeSH
• Biomechanical Phenomena MeSH
• Pharmaceutic Aids analysis   MeSH
• Research Support as Topic MeSH
• Colloids MeSH
• Rheology MeSH
• Models, Theoretical MeSH

Multilayer structure of the artery can have significant effects on the resulting mechanical behaviour of the artery wall. Separation of the artery into individual layers is sometimes performed to identify the layer-specific parameters of constitutive model proposed by Holzapfel, Gasser and Ogden (HGO model). Inspired by this single-layer model, a double-layer model was formulated and used for identification of material parameters from homogenised stress-strain data (of non-separated artery wall). The paper demonstrates that the layer-specific parameters of the double-layer constitutive model can be identified without the need of artery separation. The resulting double-layer model can credibly describe the homogenised stress-strain behaviour of the real artery wall including large-strain stiffening effects attributed to multilayer nature of the artery.

• MeSH
• Arteries physiopathology   MeSH
• Models, Biological MeSH
• Stress, Physiological MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

INTRODUCTION: The main disadvantage of a videothoracoscopic procedure is the lack of touch sensation. The probability of easily finding the lesion is usually estimated according to computed tomography (CT). AIM: To find useful parameters of location of chondromatous hamartoma of the lung parenchyma in relation to its size to assess the probability of successful search via a videothoracoscopic approach only. MATERIAL AND METHODS: A group of 55 patients operated on for chondromatous hamartoma of the lung at the First Department of Surgery in Olomouc from January 2006 to June 2011 was analyzed. Initially, the tumor's longest diameter and its nearest distance to the pleural surface were measured on CT scans. Subsequently, the surgery began using the videothoracoscopic approach. A short thoracotomy with direct palpation followed when videothoracoscopy failed. RESULTS: No significant differences in age, sex and side of localization between the group with and without successful videothoracoscopic detection were found. A significant difference was found in the median size (p = 0.026) and the depth of the tumor (p < 0.0001) and in the calculated index "tumor size/depth" (p < 0.0001). Deeper analysis revealed that the parameters "depth" and "index size/depth" are considered to be good predictors but the parameter "size" is not a suitable predictor. CONCLUSIONS: The main predictors of successful videothoracoscopic detection of lung chondromatous hamartoma are considered to be the depth of the tumor in the lung parenchyma with a cut-off value ≤ 7.5 mm and the index "size/depth" with a cut-off value ≥ 1.54; the tumor size is not considered to be a good predictor.

• Publication type
• Journal Article MeSH

The nondestructive identification of both inorganic and organic compounds without the need for chemical or mechanical sample preparation is an advantage of the Raman spectroscopic analytical technique when applied in situ using miniaturized equipment for the geosciences. This is critically assessed here for several real life geoscientific scenarios in which several groups of minerals were analyzed with emphasis on evaporites, carbonates, and selected types of dark minerals and weak Raman scatterers. The role of individual analytical instrumental parameters such as focal plane precision, exposure time, and ambient light conditions that can affect the acquisition and interpretation of spectroscopic data from these specimens in field conditions was also evaluated.

• MeSH
• Equipment Failure Analysis MeSH
• Equipment Design MeSH
• Geology instrumentation   MeSH
• Minerals analysis   chemistry   MeSH
• Miniaturization MeSH
• Spectrum Analysis, Raman instrumentation   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

• MeSH
• Anatomy MeSH
• Skeleton MeSH

• Conspectus
• Anatomie člověka a srovnávací anatomie
• NML Fields
• anatomie

Soft tissues are pseudoelastic anisotropic materials; various formulas for their strain energy density have been proposed for modelling of their constitutive behaviour. However, the individual variance of elastic parameters is often more pronounced than their anisotropy, so that their constitutive relations can be modelled as either isotropic or orthotropic. Any hyperelastic model requires more mechanical tests to be input for an identification of its parameters than mere uniaxial tension tests; especially biaxial tension tests are very important also for isotropic hyperelastic materials. A design of a testing rig produced in cooperation of our institute with some local companies is presented. It enables us to carry out not only equibiaxial tension tests, but also some other biaxial tensile tests, because displacements in both mutually perpendicular directions can be controlled independently. The proposal of various types of biaxial tests is presented in the paper, with examples of their realization with porcine aortic wall tissue. The contribution focuses on ways of evaluation of the results and on identification of parameters of various constitutive models. The use of more mechanical tests in identification of constitutive parameters can improve the predictive capability of the models substantially.

• MeSH
• Arteries physiology   MeSH
• Biomechanical Phenomena MeSH
• Elastic Tissue physiology   MeSH
• Stress, Mechanical MeSH
• Tensile Strength MeSH
• Computer Simulation MeSH
• Connective Tissue physiology   MeSH
• Swine MeSH
• Elasticity MeSH
• Models, Statistical MeSH
• Models, Theoretical MeSH
• Materials Testing MeSH
• Imaging, Three-Dimensional MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Evaluation Study MeSH

BACKGROUND This real-world study aimed to investigate the use of the Alcohol Use Disorders Identification Test (AUDIT) in men admitted to a psychiatric hospital. MATERIAL AND METHODS The AUDIT questionnaire (10 items) was consecutively administered for a period of 3 years to male patients admitted to a psychiatric hospital (n=636). Laboratory blood tests of biochemical parameters were measured as biomarkers of alcohol consumption. Data were evaluated using linear models with mixed effects in the case of continuous dependent variables and logistic regression models with mixed effects in the case of categorical dependent variables. RESULTS We found that 45.3% of the patients had a high risk of alcohol consumption or alcohol dependence and 54.7% had a low risk of alcohol consumption. The ICD-10 diagnoses of alcohol-related disorders (F1x), psychotic disorders (F2x), affective disorders (F3x), neurotic and psychosomatic disorders (F4x) were statistically significantly associated with total AUDIT score (P<0.001). There was a statistically significant association between the total AUDIT score and length of hospitalization (P=0.004) and the incidence of suicidal thoughts (P=0.003). Plasma concentrations of alanine aminotransferase (P=0.005), aspartate aminotransferase (P<0.001), gamma glutamyltransferase (P=0.001), total cholesterol (P=0.027) and mean corpuscular value of erythrocytes (P<0.001) were statistically significantly increased with a higher AUDIT score. CONCLUSIONS This real-world study showed that the AUDIT questionnaire evaluated the severity of disorders caused by alcohol and their impact on comorbid mental disorders. These results may be helpful in improving targeted interventions in this group of patients.

• MeSH
• Alcoholism diagnosis   epidemiology   MeSH
• Biometry MeSH
• Adult MeSH
• Hospitalization MeSH
• Middle Aged MeSH
• Humans MeSH
• Alcohol Drinking epidemiology   MeSH
• Mass Screening MeSH
• Surveys and Questionnaires * MeSH
• Hospitals, Psychiatric * MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Czech Republic MeSH

• MeSH
• Chemistry MeSH
• No-Observed-Adverse-Effect Level MeSH
• Pharmacokinetics MeSH
• Genetic Variation MeSH
• Risk Assessment standards   MeSH
• Specialty Uses of Chemicals MeSH
• Toxicity Tests MeSH
• Publication type
• Guideline MeSH

• Conspectus
• Chemie. Mineralogické vědy
• NML Fields
• chemie, klinická chemie
• NML Publication type
• publikace WHO

• MeSH
• Algorithms MeSH
• Informatics MeSH

• Conspectus
• Lékařské vědy. Lékařství
• NML Fields
• lékařská informatika