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The Internet of Things (IoT) is experiencing widespread adoption across industry sectors ranging from supply chain management to smart cities, buildings, and health monitoring. However, most software architectures for the IoT deployment rely on centralized cloud computing infrastructures to provide storage and computing power, as cloud providers have high economic incentives to organize their infrastructure into clusters. Despite these incentives, there has been a recent shift from centralized to decentralized architectures that harness the potential of edge devices, reduce network latency, and lower infrastructure costs to support IoT applications. This shift has resulted in new edge computing architectures, but many still rely on centralized solutions for managing applications. A truly decentralized approach would offer interesting properties required for IoT use cases. In this paper, we introduce a decentralized architecture tailored for large-scale deployments of peer-to-peer IoT sensor networks and capable of run-time application migration. We propose a leader election consensus protocol for permissioned distributed networks that only requires one series of messages in order to commit to a change. The solution combines a blockchain consensus protocol using Verifiable Delay Functions (VDF) to achieve decentralized randomness, fault tolerance, transparency, and no single point of failure. We validate our solution by testing and analyzing the performance of our reference implementation. Our results show that nodes are able to reach consensus consistently, and the VDF proofs can be used as an entropy pool for decentralized randomness. We show that our system can perform autonomous real-time application migrations. Finally, we conclude that the implementation is scalable by testing it on 100 consensus nodes running 200 applications.

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Background: According to recently published 24-hour movement guidelines, adults should spend: ≥150 minutes/week in moderate-to-vigorous physical activity (MVPA); <8 hours/day in sedentary behaviour (SB); and 7-9 hours/day sleeping. Objective: We explored the association between meeting these recommendations and low back pain (LBP)-the most common musculoskeletal disorder. Methods: We collected self-reported data from 2333 adults about: MVPA, SB and sleep duration; frequency and intensity of LBP; and sociodemographic and lifestyle characteristics. Results: Meeting a combination of SB and sleep recommendations was associated with lower odds of LBP in the past week and past month (adjusted odds ratio [OR]: 0.64 and 0.52, respectively; p < 0.05 for both). Among LBP sufferers, meeting any combination of recommendations that includes sleep was associated with lower odds of frequent (OR range: 0.49-0.61; p < 0.05 for all) and intense (OR range: 0.39-0.66; p < 0.05 for all) LBP in the past week, while meeting a combination of SB and sleep recommendations or all three recommendations was associated with lower odds of intense LBP in the past month and past year (OR range: 0.50-0.68; p < 0.05 for all). The likelihood of experiencing higher frequency and intensity of LBP decreased with the number of recommendations met (p for linear trend < 0.05). Conclusion: Meeting the SB and sleep recommendations in combination is associated with a lower likelihood of LBP, while adhering to the overall 24-hour movement guidelines or any combination of recommendations that includes sleep is associated with lower frequency and intensity of LBP among LBP sufferers.

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BACKGROUND: Adequate school furniture is important to prevent musculoskeletal discomfort among students. OBJECTIVE: The aim of the study was to assess the suitability of school furniture compared to body dimensions of students. METHODS: A cross-sectional study included a total of 442 students from primary school, secondary school, and university. Nine body dimensions along with five furniture dimensions were measured and equations for mismatch criteria were applied. RESULTS: In primary school, differences in body dimensions were more evident among students of different age, while in secondary school and university, differences between male and female students became more apparent. The mismatch for desk height ranged from 100.0% at primary school to 48.0% at university. Similarly, the seat height mismatch was the most evident in primary school (89.7% -94.6%), lower at university (52.0%) and the lowest in secondary school (18.0%). The seat depth mismatch was present among all groups, ranging from 23.1% to 40.4%, and was in general more pronounced in males. Seat to desk clearance mismatch was the most evident among secondary school students. In primary school, seat and desk height were generally too high for most of students. CONCLUSIONS: Specific differences in body dimensions among groups of students of different age and gender were observed and a high student-furniture mismatch was identified in all educational institutions. Implementation of adjustable school furniture, covering at least two size marks, is needed to provide ergonomic and healthy learning conditions and to further enhance the comfort and well-being of students in the classroom.

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Sleep, sedentary behaviour (SB), and physical activity are among key behavioural determinants of health. There is a need to evaluate questionnaires that capture movement behaviours across the full 24-h day. The aim of this study was to examine the measurement properties of the Daily Activity Behaviours Questionnaire (DABQ), a novel questionnaire (with a past seven-day recall period) for estimating the time spent in sleep, SB, light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA) among adults. A sample of 126 adults was recruited. DABQ was administered to the participants on two occasions seven days apart to examine its test-retest reliability. The convergent validity of DABQ estimates was explored against activPAL4 accelerometer/inclinometer estimates. Intraclass correlation coefficients for absolute agreement and consistency between the times spent in sleep, SB, LPA, and MVPA estimated by DABQ in the test and re-test ranged from 0.59 to 0.69. Spearman's correlations between the times spent in sleep, SB, LPA, and MVPA estimated by DABQ and activPAL4 ranged from 0.38 to 0.66. In terms of reliability and validity, DABQ is comparable with existing questionnaires; however, it has an important advantage of enabling a comprehensive assessment of all four 24-h movement behaviours. The measurement properties of DABQ make it suitable for large-scale epidemiological studies on 24-h movement behaviours.

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Background: Information and communication technology solutions have the potential to support active and healthy aging and improve monitoring and treatment outcomes. To make such solutions acceptable, all stakeholders must be involved in the requirements elicitation process. Due to the COVID-19 situation, alternative approaches to commonly used face-to-face methods must often be used. One aim of the current article is to share a unique experience from the Pharaon project where due to the COVID-19 outbreak alternative elicitation methods were used. In addition, an overview of common functional, quality, and emotional goals identified by six pilot sites is presented to complement the knowledge about the needs of older adults. Methods: Originally planned face-to-face co-creation seminars were impossible to carry out, and all pilot sites chose alternative requirements elicitation methods that were most suitable in their situation. The elicited requirements were presented in the form of goal models. In one summary goal model, we provide an overview of common functional, quality, and emotional goals. Results: Different elicitation methods were combined based on the digital literacy of the target group and their access to digital tools. Methods applied without digital technologies were phone interviews, reviews of literature and previous projects, while by means of digital technologies online interviews, online questionnaires, and (semi-)virtual co-creation seminars were conducted. The combination of the methods allowed to involve all planned stakeholders. Virtual and semi-virtual co-creation seminars created collaborative environment comparable to face-to-face situations, while online participation helped to save the time of the participants. The most prevalent functional goals elicited were "Monitor health," "Receive advice," "Receive information." "Easy to use/comfortable," "personalized/tailored," "automatic/smart" were identified as most prevalent quality goals. Most frequently occurring emotional goals were "involved," "empowered," and "informed." Conclusion: There are alternative methods to face-to-face co-creation seminars, which effectively involve older adults and other stakeholders in the requirements elicitation process. Despite the used elicitation method, the requirements can be easily transformed into goal models to present the results in a uniform way. The common requirements across different pilots provided a strong foundation for representing detailed requirements and input for further software development processes.

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Tactile interaction between humans and elements in the built environment, such as furniture, is often underappreciated. The aim of this study was to objectively evaluate thermal properties of ten tabletop materials as well as user perceptions of those materials after use. Sixteen participants tested ten materials in a randomised order. Infrared thermography was used to determine tabletop temperature distribution and change. Materials with lower thermal effusivity (wood-based materials) in general reached higher surface temperature differences after 15 min of contact and were rated as more pleasant to touch, more suitable for writing, and more liked for everyday use. Participants' sex and forearm mass had no effect on the temperature after contact. Participants gave the highest ratings to the appearance of oak-based materials. Surface treatment affected subjective evaluation of the materials. The tabletop made of lacquered solid wood had the most favourable thermal and user-rated characteristics.

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The authors wish to make the following two corrections to this paper [...].

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BACKGROUND: Muscle coordination is important for rational and effective planning of therapeutic and exercise interventions using equipment that mimics functional movements. Our study was the first to assess muscle coordination during flywheel (FW) squats. METHODS: Time-of-peak electromyographic activation order was assessed separately for 8, 4, and 3 leg muscles under four FW loads. A sequential rank agreement permutations tests (SRA) were conducted to assess activation order and Kendall's tau was used to assess the concordance of activation order across subjects, loads and expected order of activation. RESULTS: SRA revealed a latent muscle activation order at loads 0.05, 0.075, and 0.1, but not at 0.025 kg·m2. Kendall's tau showed moderate-to-strong concordance between the expected (proximal-to-distal) and the observed muscle activation order only at a load 0.025 kg·m2, regardless of the number of muscles analyzed. Muscle activation order was highly concordant between loads 0.05, 0.075, and 0.1 kg·m2. CONCLUSIONS: The results show a specific role of each muscle during the FW squat that is load-dependent. While the lowest load follows the proximal-to-distal principle of muscle activation, higher loads lead to a reorganization of the underlying muscle coordination mechanisms. They require a specific and stable muscle coordination pattern that is not proximal-to-distal.

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This study investigated the effect of hemp fiber pretreatments (water and sodium hydroxide) combined with silane treatment, first on the fiber properties (microscale) and then on polylactide (PLA) composite properties (macroscale). At the microscale, Fourier transform infrared, thermogravimetric analysis, and scanning electron microscopy investigations highlighted structural alterations in the fibers, with the removal of targeted components and rearrangement in the cell wall. These structural changes influenced unitary fiber properties. At the macroscale, both pretreatments increased the composites' tensile properties, despite their negative impact on fiber performance. Additionally, silane treatment improved composite performance thanks to higher performance of the fibers themselves and improved fiber compatibility with the PLA matrix brought on by the silane couplings. PLA composites reinforced by 30 wt.% alkali and silane treated hemp fibers exhibited the highest tensile strength (62 MPa), flexural strength (113 MPa), and Young's modulus (7.6 GPa). Overall, the paper demonstrates the applicability of locally grown, frost-retted hemp fibers for the development of bio-based composites with low density (1.13 to 1.23 g cm-3).