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- Arumugam, Ashokan, et al.
(författare)
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Sedentary and physical activity time differs between self-reported ATLS-2 physical activity questionnaire and accelerometer measurements in adolescents and young adults in the United Arab Emirates
- 2023
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Ingår i: BMC Public Health. - : BioMed Central (BMC). - 1471-2458. ; 23:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Most young adults and adolescents in the United Arab Emirates (UAE) do not meet the established internationally recommended physical activity levels per day. The Arab Teen Lifestyle Study (ATLS) physical activity questionnaire has been recommended for measuring self-reported physical activity of Arab adolescents and young adults (aged 14 years to mid-twenties). The first version of the ATLS has been validated with accelerometers and pedometers (r ≤ 0.30). The revised version of the questionnaire (ATLS-2, 2021) needs further validation. The aim of this study was to validate the self-reported subjective sedentary and physical activity time of the ATLS-2 (revised version) physical activity questionnaire with that of Fibion accelerometer-measured data.METHODS: In this cross-sectional study, 131 healthy adolescents and young adults (aged 20.47 ± 2.16 [mean ± SD] years (range 14-25 years), body mass index 23.09 ± 4.45 (kg/m2) completed the ATLS-2 and wore the Fibion accelerometer for a maximum of 7 days. Participants (n = 131; 81% non-UAE Arabs (n = 106), 13% Asians (n = 17) and 6% Emiratis (n = 8)) with valid ATLS-2 data without missing scores and Fibion data of minimum 10 h/day for at least 3 weekdays and 1 weekend day were analyzed. Concurrent validity between the two methods was assessed by the Spearman rho correlation and Bland-Altman plots.RESULTS: The questionnaire underestimated sedentary and physical activity time compared to the accelerometer data. Only negligible to weak correlations (r ≤ 0.12; p > 0.05) were found for sitting, walking, cycling, moderate intensity activity, high intensity activity and total activity time. In addition, a proportional/systematic bias was evident in the plots for all but two (walking and moderate intensity activity time) of the outcome measures of interest.CONCLUSIONS: Overall, self-reported ATLS-2 sedentary and physical activity time had low correlation and agreement with objective Fibion accelerometer measurements in adolescents and young adults in the UAE. Therefore, sedentary and physical activity assessment for these groups should not be limited to self-reported measures.
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| 4. |
- Rashid, Farhan Lafta, et al.
(författare)
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Analysis of heat transfer in various cavity geometries with and without nano-enhanced phase change material: A review
- 2023
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Ingår i: Energy Reports. - : Elsevier. - 2352-4847. ; 10, s. 3757-3779
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Forskningsöversikt (refereegranskat)abstract
- Numerous heating and cooling design methods, including energy storage, geothermal resources, heaters, solar collectors, underground water movement, lakes, and nuclear reactors, require the study of flow regimes in a cavity and their impact on thermal efficiency in heat transportation. Despite the existence of several review studies in the open literature, there is no specific review of heat transfer investigations that consider different cavity designs, such as spheres, squares, trapezoids, and triangles. Therefore, this work aims to conduct a comprehensive review of previous research published between 2016 and 2023 on heat transfer analysis in these cavity designs. The intention is to clarify how various cavity shapes perform in terms of flow and heat transfer, both with and without the addition of nano-enhanced phase change materials (NePCMs), which may include fins, obstacles, cylinders, and baffles. The study also explores the influence of factors like thermophoresis, buoyancy, magnetic forces, and others on heat transport in cavities. Additionally, it investigates the role of air, water, nanofluids, and hybrid nanofluids within cavities. According to the reviewed research, nanoparticles in the base fluid speed up the cooling process and reduce the required discharging time. Thermophoresis, where nanoparticles move from the heated wall to the cold nanofluid flow, becomes more pronounced with increasing Reynolds numbers. Increasing the heated area of the lower flat fin enhances the heat transfer rate, while increasing both the Rayleigh number and the solid volume percentage of nanoparticles reduces it. Radiation blockage alters the path of hot particles and affects the anticipated radiative amount. Optical thickness plays a role in rapidly cooling a medium, and partition thickness has the most significant effect on heat transport when the thermal conductivity ratio is low. Heat transmission is most improved when the Rayleigh number is high and the Richardson number is low.
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