Damage Characterization during Compression in a Perlite-Aluminum Syntactic Foam

Aluminum matrix (Al99.5) syntactic foam containing expanded perlite particles was produced using the pressure infiltration technique. The dominant deformation mechanisms during compression of this foam were determined by sequential k-means analysis of the acoustic emission data. Since the different deformation mechanisms were concurrently active even at small strains, successive unloading and reloading measurement was proposed for cluster identification. The repetitive unloading and reloading allowed us to identify two mechanical parameters, namely the unloading modulus and the loss for unloading-reloading cycles. Based on the correlations among the strain localization within the specimen, the acoustic emission results, the changes in these mechanical parameters, and the transition from quasi-elastic deformation to plasticity were revealed in this material

The Concept of the Implementation of Present Evidence-based Knowledge and Technology into the Preparation of Sport Professionals

AbstractThe study assesses the feasibility of the concept of professional preparation of sport teachers and instructors that attempts to connect education and research activities with the emphasis on presenting evidence-based knowledge and new technologies. The seven-year-long international study involved 670-850 university students annually. Students participated directly in the research activities that were in compliance with the curricula of sport education study programs. The presented educational model describes possibilities and major limits how to provide dozens evidence-based knowledge of prospective sport professionals in the areas of physical activity monitoring, self-assessment of physical fitness and evaluation of sport preferences

Monitoring the failure mechanisms in metal matrix syntactic foams during compression by acoustic emission

Syntactic foam containing hollow ceramic spheres with an average outer diameter of 1.45 mm and wall thickness of 58 µm was produced using the pressure infiltration technique. This paper presents the analysis of the compressive deformation mechanisms of these syntactic foams using the acoustic emission (AE) technique. The active deformation mechanisms are determined by sequential k-means analysis of the AE data. The analysis revealed three dominant deformation mechanisms: plastic deformation of the cell walls, sphere fracture, and cell wall collapse. The AE results obtained are in good correlation with the findings of the visual inspection of the surface of the specimen, suggesting that the active deformation mechanisms in the whole volume of the specimen can be determined by this technique

Non-alloyed Ni3Al based alloys – preparation and evaluation of mechanical properties

The paper reports on the fabrication and mechanical properties of Ni3Al based alloy, which represents the most frequently used basic composition of nickel based intermetallic alloys for high temperature applications. The structure of the alloy was controlled through directional solidifi cation. The samples had a multi-phase microstructure. The directionally solidifi ed specimens were subjected to tensile tests with concurrent measurement of acoustic emission (AE). The specimens exhibited considerable room temperature ductility before fracture. During tensile testing an intensive AE was observed.Web of Science52331230

The influence of educational attainment and age on the amount and type of physical activity of inhabitants in Pilsen region

BACKGROUND: Frequent participation in physical activity (PA) of any kind is an important part of the behavior of each individual and leads to maintaining health and preventing diseases of civilization. We assume that people with higher levels of education perform more PA than people with primary and secondary education. OBJECTIVES: The aim of this study was to analyze the amount and type of PA of the inhabitants of the Pilsen region from the aspect of their gender, education level, and age. The next goal was to estimate the percentage of male and female participants meeting the recommended amounts of PA (taking into consideration their age and education level). METHODS: For analysis we used the IPAQ questionnaires (long version), which were distributed in the years 2005-2009 to randomly selected families in the spring and autumn months. In total 1125 correctly completed questionnaires were processed using non-parametric Kruskal-Wallis test (513 men and 612 women aged 25-58 years). RESULTS: The total physical activity of men increased with their age and decreased with the level of attained education. In women, the relationship between the total PA, age, and education was not observed. Recommendations for PA are fulfilled more likely by younger men (46.6% meet recommendations for vigorous PA, 60.9% meet the recommendations for walking) who attained primary education (48.5% meet recommendations for moderate PA, 61.3% meet recommendations for walking) and by women who attained university education (48.5% meet recommendations for moderate PA, 68.5% meet the recommendations for walking). CONCLUSIONS: The results of the analysis of the questionnaires suggest that in men from the Pilsen region there is a relationship between the total weekly physical activity level, age and education level, while in women a clear relationship between the PA, age and attained education level was not documented

Physical activity and life satisfaction among adolescents before and during the COVID-19 pandemic

The negative impact of the COVID-19 pandemic and distance education has significantly affected adolescents' lives. The restrictive policies negatively affected their physical and mental health and life satisfaction. It is therefore desirable to look for ways to eliminate similar negative impacts on adolescents in the future. This study aimed to identify the differences in the association between physical activity and life satisfaction in Polish adolescents before and during the pandemic. The study included 1541 participants (891 before the pandemic and 650 during the pandemic) aged 15–19 years. The International Physical Activity Questionnaire-Long Form questionnaire was used to assess physical activity, and the Bern Subjective Well-Being Questionnaire was used to evaluate life satisfaction. The objectivity of data collection and analysis before and during the pandemic was ensured by the web application the International Database for Research and Educational Support. During the pandemic, we found lower physical activity and life satisfaction in both boys and girls compared to before the pandemic. Girls with low and high physical activity levels showed significantly lower life satisfaction during the pandemic than they did before. Low life satisfaction was associated with lower physical activity, and high life satisfaction was associated with greater total physical activity. Both boys and girls with low and high life satisfaction achieved significantly fewer physical activity recommendations during the pandemic. High life satisfaction increased the likelihood of meeting the recommendations for physical activity before and during the pandemic. This study provides new insights into the differences and associations between life satisfaction and physical activity in adolescent boys and girls before and during the pandemic. It provides suggestions for the prevention of possible future restrictions in the school settings. Support for post-pandemic life satisfaction in adolescents should focus mainly on increasing vigorous physical activity and improving adolescent participation in organized physical activity settings

Strength asymmetry of the knee extensors and physical activity in middle-aged women

<b>Background: </b>Differences between muscle strength and power of lower limbs is one of the factors associated with falls in the elderly population. Muscle strength asymmetry of lower limbs increases with age. <b>Objective:</b> The aim of the study is to assess differences in the volume and intensity of physical activity (PA) in the subgroups of women being at higher and lower risk of falls (with and without strength asymmetry of the knee extensors of dominant and non-dominant lower limb). <b>Methods:</b> Data from 42 women (age 56.3&#x202F;&plusmn;&#x202F;4.4 years; weight 76.5&#x202F;&plusmn;&#x202F;16.1&#x202F;kg; body height 164.3&#x202F;&plusmn;&#x202F;5.2&#x202F;cm; body mass index 28.1&#x202F;&plusmn;&#x202F;5.3&#x202F;kg . m^-2) were used for the purpose of the presented analysis. Furthermore the sample was divided into subgroups with lower and higher strength asymmetry of quadriceps muscle (as a criterion the asymmetry greater than 15% was chosen). Absolute concentric peak torque of the knee extensors was evaluated by an isokinetic dynamometer IsoMed 2000 in a sitting position at angular velocity of 180° . s^-1. PA was monitored using Yamax SW-700 pedometers throughout 7 consecutive days and using the Czech version of standardized International Physical Activity Questionnaire. <b>Results:</b> Statistically significant differences between groups with lower and higher strength asymmetry were found in the amount of self-reported vigorous PA (<i>p</i><i> </i>=&#x202F;.04; <i>d</i><i> </i>=&#x202F;0.6) only. Differences between the observed groups were not significant in self-reported moderate PA and walking. There were also no significant differences in the daily numbers of steps measured objectively. <b>Conclusions: </b>The results of the study indicate that from the point of view of strength asymmetry of knee extensors as a factor associated with falls in middle-aged women, intensity of PA could be an important characteristic of PA. This suggestion should be taken into account in habitual PA and training programs in middle-aged population