Effects of Age and Loading Velocity on the Delamination Strength of the Human Aorta

Delamination strength is the mechanical property which plays a key role in the pathological process referred to as Arterial Dissection. This dissection, known especially for its occurrence in the thoracic aorta, is manifested by a separation of the layers of an artery wall, and may end with total rupture and internal haemorrhaging. Although its incidence is relatively rare, from 3 to 6 cases per 100 000 per year, it is a life-threating disease with a significant lethality [1-3]. The exact conditions under which the dissection is initiated, and as a crack propagates through the arterial wall, remain an open topic in computational as well as experimental mechanics. The aim of our study is to contribute to the deepening of our knowledge of Arterial Dissection, by collecting experimental data which is suitable for the purpose of showing how the delamination strength measured in the peeling experiments depends on age and anatomical location. In addition to the effects of age and location, our study also focuses on the effect of loading rate. The experimental branch of our research is complemented by a computational modelling of the delamination interface, in which we are looking for a numerical characterization of the material parameters describing discontinuity propagation. An XFEM model of the peeling experiment is built in Abaqus, which in our approach plays the role of the regression analysis, incorporating the cohesive zone (CZ) in order to model the delaminating arterial layers. The main objective is to obtain a detailed description of a set of constitutive parameters, which would be age- and location-specific. Our present data suggest that delamination strength strongly depends on age, and furthermore, the anatomical site also seems to be a significant factor. On the other hand, the loading velocity does not cause significant changes in results

The Phenomenon of Social and Pastoral Service in Eastern Slovakia and Northwestern Czech Republic during the COVID-19 Pandemic: Comparison of Two Selected Units of Former Czechoslovakia in the Context of the Perspective of Positive Solutions

This study seeks to explain the differences in the perception of social and pastoral service after the first and second wave pandemic in 2020 among the inhabitants of two neighbouring states, both parts of the former unified Czechoslovakia. Our research study compares subjective perception, needs, and participation among inhabitants of eastern Slovakia and north-western Czech Republic in social and pastoral service during the COVID-19 pandemic. The research sample consisted of a healthy population from the Czech Republic (n = 496) and Slovakia (n = 484) over 16 years of age, of which 63% (n = 617) were women and 37% (n = 363) men. The level of education ranged from primary to postgraduate. The research sample consisted of 623 (63.6%) participants with religious affiliation and 357 (36.4%) without religion. The level of perception, needs, and participation of the participants in social and pastoral service was obtained based on a non-standardised questionnaire. The results of our study confirmed several differences in the areas studied. © 2022 by the authors. Licensee MDPI, Basel, Switzerland