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1.
Fluid flow simulation with an ▫$ℋ^2$▫ -accelerated boundary-domain integral method
Jan Tibaut, Jure Ravnik, M Schanz, 2024, original scientific article

Abstract: The development of new numerical methods for fluid flow simulations is challenging but such tools may help to understand flow problems better. Here, the Boundary-Domain Integral Method is applied to simulate laminar fluid flow governed by a dimensionless velocity–vorticity formulation of the Navier–Stokes equation. The Reynolds number is chosen in all examples small enough to ensure laminar flow conditions. The false transient approach is utilized to improve stability. As all boundary element methods, the Boundary-Domain Integral Method has a quadratic complexity. Here, the ℋ2 -methodology is applied to obtain an almost linear complexity. This acceleration technique is not only applied to the boundary only part but more important to the domain related part of the formulation. The application of the ℋ2 -methodology does not allow to use the rigid body method to determine the singular integrals and the integral free term as done until now. It is shown how to apply the technique of Guigiani and Gigante to handle the strongly singular integrals in this application. Further, a parametric study shows the influence of the introduced approximation parameters. For this purpose the example of a lid driven cavity is utilized. The second example demonstrates the performance of the proposed method by simulating the Hagen–Poiseuille flow in a pipe. The third example considers the flow around a rigid cylinder to show the behavior of the method for an unstructured grid. All examples show that the proposed method results in an almost linear complexity as the mathematical analysis promisses.
Keywords: boundary-domain integral method, velocity–vorticity, adaptive cross approximation, modified helmholtz equation, Yukawa potential, fast multipole method, ℋ-structure
Published in DKUM: 28.11.2024; Views: 0; Downloads: 4
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2.
Factors affecting attitudes towards COVID-19 vaccination : an online survey in Slovenia
Luka Petravić, Rok Arh, Tina Gabrovec, Lucija Jazbec, Nika Rupčić, Nina Starešinič, Lea Zorman, Ajda Pretnar Žagar, Andrej Srakar, Matjaž Zwitter, Ana Slavec, 2021, original scientific article

Abstract: While the problem of vaccine hesitancy is not new, it has become more pronounced with the new COVID-19 vaccines and represents an obstacle to resolving the crisis. Even people who would usually trust vaccines and experts now prefer to wait for more information. A cross-sectional online survey was conducted in Slovenia in December 2020 to find out the attitudes of the population regarding COVID-19 vaccination and the factors that affect these attitudes. Based on 12,042 fully completed questionnaires, we find that higher intention to get vaccinated is associated with men, older respondents, physicians and medical students, respondents who got the influenza vaccination, those who knew someone who had gotten hospitalised or died from COVID-19 and those who have more trust in experts, institutions and vaccines. Nurses and technicians were less likely to get vaccinated. In answers to an open question, sceptics were split into those doubting the quality due to the rapid development of the vaccine and those that reported personal experiences with side effects of prior vaccinations. Although the Slovenian population is diverse in its attitudes towards vaccination, the results are comparable to those found in other countries. However, there are potential limitations to the generalizability of the findings that should be addressed in future studies.
Keywords: cross-sectional studies, intention, public opinion, trust, ordinal regression, COVID-19, vaccination, surveys and questionnaires, Europe, immune system, SARS-CoV-2
Published in DKUM: 10.10.2024; Views: 0; Downloads: 7
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3.
Influence of cross-linkers on the wash resistance of chitosan-functionalized polyester fabrics
Tanja Pušić, Tea Bušac, Julija Volmajer Valh, 2024, original scientific article

Abstract: This study investigates the wash resistance of polyester fabrics functionalized with chitosan, a biopolymer known for its biocompatibility, non-toxicity, biodegradability and environmentally friendly properties. The interaction of chitosan with synthetic polymers, such as polyester, often requires surface treatment due to the weak natural affinity between the two materials. To improve the interaction and stability of chitosan on polyester, alkaline hydrolysis of the polyester fabric was used as a surface treatment method. The effectiveness of using cross-linking agents 1,2,3,4-butane tetracarboxylic acid (BTCA) and hydroxyethyl methacrylate (HEMA) in combination with ammonium persulphate (APS) to improve the stability of chitosan on polyester during washing was investigated. The wash resistance of polyester fabrics functionalized with chitosan was tested after 1, 5 and 10 washes with a standard ECE detergent. Staining tests were carried out to evaluate the retention of chitosan on the fabric. The results showed that polyester fabrics functionalized with chitosan without cross-linkers exhibited better wash resistance than the fabrics treated with crosslinkers.
Keywords: polyster, functionalization, chitosan, cross-linkers, stability, washing
Published in DKUM: 10.09.2024; Views: 55; Downloads: 8
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4.
Differences in subject-specific competences between Slovenian and Italian physical education teachers
Marjeta Kovač, Bojan Leskošek, Gregor Jurak, Miha Marinšek, Miloš Tul, 2021, original scientific article

Abstract: This cross-sectional study was designed to analyse the differences between the subject-specific competences of Slovenian and Italian physical education (PE) teachers. The participants, 669 Slovenian and 484 Italian PE teachers, evaluated their professional competences with a self-administered questionnaire on a four-level Likert scale. A t-test for independent samples indicates differences in the self-evaluations of the majority of subject-specific competences between both groups. However, in almost all items, Slovenian PE teachers evaluate their competences higher. A multivariate analysis of variance, used to identify the role of some socio-demographic factors (state, gender, years of service), shows that the state has the highest impact on the differences between self-efficiency of both groups (p<0.001, Eta2=0.531). The greatest differences (Cohen's d > 0.8) are observed on those competences that relate to some of the narrower aspects of PE didactics. The reasons for the perceived differences can be found in some historical and social events, length of education, the different orientation of PE teacher education programmes, and the different responses of both countries to educational policies. The present study outcomes may aid in updating initial PE teacher training and designing a creative system of continuous professional development.
Keywords: physical education, educators, self-efficiency, cross-cultural study
Published in DKUM: 04.09.2024; Views: 41; Downloads: 4
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5.
Measuring religious costs and rewards in a cross-cultural perspective
Miran Lavrič, Sergej Flere, 2010, original scientific article

Abstract: The assumption of rationally motivated individual religious behavior was tested in a survey of undergraduate university students from four different cultural/religious environments: Slovenia, Bosnia and Herzegovina, Serbia, and the United States of America. In particular, an attempt was made to explain readiness to bear religious costs by the expectation of otherworldly rewards and some other variables, such as religious socialization, support in the upbringing of children, religious capital, satisfaction with religious services and the perceived social sanctions for possible religious nonparticipation. It was found that it is the otherworldly rewards in all the samples that explain by far the major part of the variance in the readiness to bear religious costs. These results suggest that individuals do tend to make rational choices even when it comes to religion. Based on their beliefs, they are ready to accept religious costs approximately to the level of their expectation of otherworldly rewards.
Keywords: medkulturne študije, racionalna izbira, religija, verski izdatki, verske nagrade, cross-cultural studies, racional choice, religion, religious costs, religious rewards
Published in DKUM: 02.08.2024; Views: 78; Downloads: 4
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6.
COVID-19 and social distancing : ǂa ǂcross-cultural study of interpersonal distance preferences and touch behaviors before and during the pandemic
Ilona Croy, Andreja Avsec, Tina Kavčič, Bojan Musil, Nejc Plohl, Gaja Zager Kocjan, Maja Zupančič, 2024, original scientific article

Abstract: The COVID-19 pandemic has led to the introduction of unprecedented safety measures, one of them being physical distancing recommendations. Here, we assessed whether the pandemic has led to long-term effects on two important physical distancing aspects, namely interpersonal distance preferences and interpersonal touch behaviors. We analyzed nearly 14,000 individual cases from two large, cross-cultural surveys – the first conducted 2 years prior to the pandemic and the second during a relatively stable period of a decreased infection rate in May-June 2021. Preferred interpersonal distances increased by 54% globally during the COVID-19 pandemic. This increase was observable across all types of relationships, all countries, and was more pronounced in individuals with higher self-reported vulnerability to diseases. Unexpectedly, participants reported a higher incidence of interpersonal touch behaviors during than before the pandemic. We discuss our results in the context of prosocial and self-protection motivations that potentially promote different social behaviors.
Keywords: neverbalna komunikacija, preference glede medosebne razdalje, medosebni dotiki, pandemija, kovid, COVID-19, fizična distanca, medkulturna psihologija, coronavirus, nonverbal communication, interpersonal distance preferences, interpersonal touch behaviour, cross-cultural psychology, physical distancing
Published in DKUM: 02.08.2024; Views: 89; Downloads: 5
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7.
Fall risk in adult family practice non-attenders : a cross-sectional study from Slovenia
Nina Ružić Gorenjec, Zalika Klemenc-Ketiš, Rok Blagus, Tonka Poplas-Susič, 2023, original scientific article

Abstract: Introduction: Not much is known about the fall risk among the adult population of those who rarely visit doctors. We wanted to determine the prevalence of increased fall risk in a population of family practice non-attenders and the factors associated with it. Methods: We included participants from family medicine practices in this cross-sectional study. To be included in the study, the participants had to be adults living in the community (home-dwelling people) who had not visited their chosen family physician in the last five years (non-attenders). The identification of the eligible persons was done through a search of electronic medical records, which yield 2,025 non-attenders. Community nurses collected data in the participants’ homes. The outcome measure was increased fall risk as assessed by the Morse fall scale: increased risk (≥25) vs. no risk. Results: The sample consisted of 1,945 patients (96.0% response rate) with a mean age of 60.4 years (range 20.5 to 99.7 years). An increased fall risk was determined in 482 or 24.8% (95% CI: [22.9, 26.8]) of the patients. The multivariate model showed a significant association of increased fall risk with higher age (p<0.001), lower systolic blood pressure (p=0.047), poor family function (p=0.016), increased risk of malnutrition (p=0.013), higher number of chronic diseases (p=0.027), higher pain intensity (p<0.001), lower self-assessment of current health (p=0.002), and higher dependence in daily activities (p<0.001). Conclusion: Non-attenders may have an increased risk of falling which depends on their health status and age. The inclusion of community nurses in primary healthcare teams could be of use not only to identify the non-attenders’ health needs, but also to better manage their health, especially the factors that were identified to be associated with greater fall risk.
Keywords: fall risk, primary healthcare, family practice, non-attenders, cross-sectional studies
Published in DKUM: 17.07.2024; Views: 125; Downloads: 4
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8.
Sustainable design of circular reinforced concrete column sections via multi-objective optimization
Primož Jelušič, Tomaž Žula, 2023, original scientific article

Abstract: An optimization model for reinforced concrete circular columns based on the Eurocodes is presented. With the developed optimization model, which takes into account the exact distribution of the steel reinforcement, which is not the case when designing with conventional column design charts, an optimal design for the reinforced concrete cross section is determined. The optimization model uses discrete variables, which makes the results more suitable for actual construction practice and fully exploits the structural capacity of the structure. A parametric study of the applied axial load and bending moment was performed for material cost and CO2 emissions. The results based on a single objective function show that the optimal design of the reinforced concrete column cross section obtained for the material cost objective function contains a larger cross-sectional area of concrete and a smaller area of steel compared with the optimization results when CO2 emissions are determined as the objective function. However, the optimal solution in the case where the material cost was assigned as the objective function has much more reserve in axial load capacity than in the optimal design where CO2 was chosen as the objective function. In addition, the multi-objective optimization was performed to find a set of solutions that provide the best trade-offs between the material cost and CO2 emission objectives.
Keywords: reinforced concrete columns, circular cross section, costs, CO2 emissions, multi-objective optimization, genetic algorithm
Published in DKUM: 15.04.2024; Views: 338; Downloads: 207
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9.
Association between loneliness, well-being, and life satisfaction before and during the COVID-19 pandemic : a cross-sectional study
Mateja Lorber, Jožica Černe Kolarič, Sergej Kmetec, Barbara Kegl, 2023, original scientific article

Abstract: Good psychological well-being contributes to a satisfying life, reduces loneliness, and enables a better quality of life. Due to the COVID-19 pandemic, people worldwide have faced various challenges, which manifest in mental health problems, dissatisfaction with life and increased loneliness. This study aimed to investigate the influence of loneliness on mental well-being and life satisfaction among the adult population during the COVID-19 pandemic. A cross-sectional study was conducted between October 2021 and January 2022. A total of 664 participants took part in the survey, of whom 484 (73%) were female and 180 (27%) were male. Our results show that loneliness can explain 48% of the total variability in mental well-being and 52% of the variability in life satisfaction. The results show a higher level of loneliness and use of information and communication technology and a lower level of contact with relatives and friends, life satisfaction, and well-being during COVID-19 than they considered before the time of COVID-19. Study findings can help improve loneliness and mental well-being, and, consequently, life satisfaction.
Keywords: loneliness, well-being, life satisfaction, cross-sectional study
Published in DKUM: 10.04.2024; Views: 274; Downloads: 19
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10.
Cross-Hole GPR for Soil Moisture Estimation Using Deep Learning
Blaž Pongrac, Dušan Gleich, Marko Malajner, Andrej Sarjaš, 2023, original scientific article

Abstract: This paper presents the design of a high-voltage pulse-based radar and a supervised data processing method for soil moisture estimation. The goal of this research was to design a pulse-based radar to detect changes in soil moisture using a cross-hole approach. The pulse-based radar with three transmitting antennas was placed into a 12 m deep hole, and a receiver with three receive antennas was placed into a different hole separated by 100 m from the transmitter. The pulse generator was based on a Marx generator with an LC filter, and for the receiver, the high-frequency data acquisition card was used, which can acquire signals using 3 Gigabytes per second. Used borehole antennas were designed to operate in the wide frequency band to ensure signal propagation through the soil. A deep regression convolutional network is proposed in this paper to estimate volumetric soil moisture using time-sampled signals. A regression convolutional network is extended to three dimensions to model changes in wave propagation between the transmitted and received signals. The training dataset was acquired during the period of 73 days of acquisition between two boreholes separated by 100 m. The soil moisture measurements were acquired at three points 25 m apart to provide ground truth data. Additionally, water was poured into several specially prepared boreholes between transmitter and receiver antennas to acquire additional dataset for training, validation, and testing of convolutional neural networks. Experimental results showed that the proposed system is able to detect changes in the volumetric soil moisture using Tx and Rx antennas.
Keywords: ground penetrating radar, cross-hole, L-band, deep learning, convolutional neural network, soil moisture estimation
Published in DKUM: 03.04.2024; Views: 448; Downloads: 23
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