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Ionisation Chambers
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
The charge (or current) created in the air cavity is conducted to the measuring device (the electrometer) through leads connected to the electrodes. These leads pass through the chamber stem, which is attached to the chamber cavity and designed to hold the whole assembly. Because the charge circulating between the electrodes should be restricted to that created within the air cavity, there must be no other conducting path between the electrodes except that of the ionised air, and therefore, an insulator must be provided between them. Although, in the past, various naturally occurring substances were used as insulators (amber, quartz and ceresin wax), today, synthetic plastics can be used. These are polymethyl methacrylate (PMMA), polystyrene, polyethylene, Nylon, polytetrafluoroethylene (PTFE, Teflon), Mylar film and polytrifluoro-monochloroethylene (Kel-F) (Boag 1966). Surface leakage because of humidity is resisted well by Teflon; however, Teflon is more prone to radiation damage than, for example, polystyrene.
Lifestyle-related health promotion
Published in Ben Y.F. Fong, Martin C.S. Wong, The Routledge Handbook of Public Health and the Community, 2021
The Census and Statistics Department (2017) found that spending three or more hours per day on using the Internet via electronic screen devices increased from 45.8% to 50.6% between 2015 and 2017 by children and adolescents ages of 10–14 years old. Extensive use of the Internet and electronic screen products is an example of sedentary behaviour (Table 8.2), which may displace time spent in physical activity with higher METs, leading to lower physical activity levels occurring nearly at all ages of the life course. Other factors such as failure to access to public transport, neighbourhood safety and walkability correlated with higher physical activity are also factors attributable to insufficient physical activity reported elsewhere (Cerin et al., 2019).
Validation of two self-reported physical activity instruments against accelerometer data in patients undergoing lung cancer surgery
Published in Physiotherapy Theory and Practice, 2022
Marcus Jonsson, Elisabeth Westerdahl, Anders Ahlsson, Anita Hurtig-Wennlöf
Objective measurement of physical activity was performed with an ActiGraph GT3X+ accelerometer (Manufacturing Technology Inc., Pensacola, FL, USA) at a sample frequency of 30 Hz. The output variable was counts per 10 seconds, processed by filtering and summarizing and presented as counts per minute. The accelerometer also provided number of steps. Patients were instructed to wear the device at the waist for one week, at three months after surgery. Wear time validation was conducted according to Choi, Liu, Matthews, and Buchowski (2011). Settings used were: minimum wear time per day 600 minutes; and a minimum of two wear days. Cutoff points according to Barnett, van den Hoek, Barnett, and Cerin (2016) were used to calculate: sedentary time (i.e. 0–100 vertical axis counts/min); time spent on light activity (i.e. 101–1012 vertical axis counts/min); and time spent on moderate and vigorous intensity physical activity (i.e. MVPA, ≥ 1013 vertical axis counts/min). This cut-point has been suggested for older adults and would be appropriate for the studied population. Accelerometer data were processed using the designated software (ActiLife, version 6.11.9). The patients were instructed to complete the self-reported instruments at the end of the week of wearing the accelerometer, thus covering the same time period.
Effect of morning versus evening exercise training on sleep, physical activity, fitness, fatigue and quality of life in overweight and obese adults
Published in Chronobiology International, 2021
Oussama Saidi, Etienne Colin, Mélanie Rance, Eric Doré, Bruno Pereira, Pascale Duché
Given that one of the main barriers discouraging regular physical activity is busy schedules and lack of time during the day (Cerin et al. 2010), evening exercise could offer a practical alternative to overcome this obstacle and increase adherence to exercise training. However, it remains unclear if evening exercise training is as effective as morning exercise. Currently, there is a little evidence-based research concerning the optimal timing of exercise on health outcomes in overweight and obese subjects. More importantly, while most studies dealing with the optimal time of practice have focused on weight loss, energy intake, and appetite adaptations (Alizadeh et al. 2017; Willis et al. 2020), no study to date (to our knowledge) has investigated the effect of exercise training timing on sleep among overweight and obese subjects.
The Effects of Combining PETTLEP Imagery and Action Observation on Bicep Strength: A Single-Case Design
Published in Journal of Applied Sport Psychology, 2020
Dave Smith, Stephanie Romano-Smith, David J. Wright, Ben Deller-Rust, Caroline J. Wakefield
The data from the participants’ individual 1 R.M. scores were plotted onto a graph. Visual inspection is a commonly used form of analysis in single-case designs (Kinugasa, Cerin, & Hooper, 2004). However, to produce a more robust analysis, lines representing the mean for the baseline, total intervention and each intervention phase, in addition to trend lines, were added. To further extend the analysis, binomial statistics were carried out. These tests involve calculations of the number of data points above and below trend lines to establish any significant differences and were conducted in line with previous single-case design studies (Callow, Hardy, & Hall, 2001; Wakefield & Smith, 2011). Furthermore, effect sizes were calculated using the formula proposed by Kromrey and Foster-Johnson (1996), and previously used in single case study designs of a similar nature. Based on previous data, Parker and Vannest (2009) examined effect sizes for single-case designs and proposed that an effect size of less than .87 is small, .87–2.67 is medium, and greater than 2.67 is large.