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Objectives: To determine typical speeds of skiers and snowboarders on-piste groomed trails across the United States (US). Design and methods: On-slope speeds of skiers and snowboarders were measured on trails of varying difficulty at 8 ski areas across the US. The trail difficulty designation and slope were documented for each location where speed measurements were taken. The equipment used (skis or snowboard), whether a helmet was worn, and the estimated ability (determined by the researchers) of snowsports participants were recorded. A multiple linear regression analysis was performed to determine the influence of these individual and environmental factors on the speeds of snowsports participants. Results: 4164 speed observations were made between 2004 and 2020 on groomed trails at 8 ski areas representing 5 geographic regions in the United States. Across all observations, the average speed was 34.9 ​± ​13.6 ​km/h. The ability of the snowsports participant had the largest effect on speed. Advanced snowsports participants traveled faster (44.5 ​± ​11.7 ​km/h) than intermediates (32.4 ​± ​9.9) and beginners (19.9 ​± ​7.2). Skiers on average were faster (35.8 ​± ​13.8 ​km/h) than snowboarders (33.0 ​± ​13.2 ​km/h) and beginner and intermediate snowboarders were slower on average than their skiing counterparts. While the average speeds increased with increasing trail difficulty and slope, the correlation was weak (R2 ​= ​0.15). Conclusions: The ability of the snowsports participant was found to be the most influential factor affecting speed.

Objective: Fixed obstacles, such as trees, rocks and posts, are common within recreational ski areas. Collisions with fixed obstacles (CWO) can have severe consequences with significant physical, emotional and economic costs. Despite worldwide use of ski area padding, few studies have focused on padding and CWO. The snowsports safety community is now focusing on this topic to improve safety at recreational ski areas. The objectives of this white paper are to summarize the recent work conducted on ski area padding, to identify unsolved questions about CWOs and opportunities to improve safety. Methods: A review of the current knowledge regarding CWOs and ski area padding was performed, combining scientific studies and experience from the authors and ski area safety professionals. This review covers: (i) the epidemiology of CWOs; (ii) the characteristics of CWOs; (iii) padding type and use; (iv) ski area safety professional practices; and, (v) padding performance and the limits for injury mitigation. Results: Previous studies focused on epidemiology, padding practices and performance and provide motivation for further study in the areas of: (i) prevention of CWOs; (ii) padding practices to improve safety on the slopes; (iii) requirements for padding performance; and, (iv) technological advancement of padding materials and design. Conclusions: There is a need for an international standard for ski area padding, to address the absence of padding performance requirements in most countries. Further research studies should also focus on providing guidance to ski areas on the best practices for choosing, applying, and maintaining ski area padding.

Objective: To observe chairlift restraint bar use at ski areas across the United States (US) to investigate the factors that influence restraint bar use, including: geographic region, passenger demographics, equipment type, and design features of the restraint bar. Design and method: Frequency of restraint bar use was observed on 24 chairlifts at 8 ski areas in 4 geographic regions of the US. For each chair, passengers were observed to determine whether the restraint bar was lowered soon after loading; the number of passengers, children, and equipment type were also recorded. A statistical analysis was performed to determine the factors that may influence restraint bar use. Results: 6,343 chairs with 16,286 passengers were observed. The overall frequency of restraint bar use was 41.6%; however, use varied significantly by geographic region, with the lowest use rates in the Midwest (9%) and highest use rates in the Northeast (80%). Other factors found to significantly increase use included a mix of children and adults on the chair (compared to only adults), chairs with only skiers (no snowboarders), and fixed-grip chairs (versus detachable). Restraint bar features such as footrests and handholds were not a driving factor in use. Conclusions: Large differences in restraint bar use were observed across geographic regions in the US that mimic historical snowsports helmet use, suggesting an effect of safety culture on restraint bar use. Geographic region and the presence of both a child and an adult together on the chair were stronger predictors of restraint bar use than design features of the restraint bar.

Many modern high-end vehicles exploit controllable damping solutions to enhance their adaptability to different road conditions and driving styles. Among these technologies, active dampers offer improved performance due to their four-quadrant operation in the torque–speed plane. In active electromagnetic dampers, brushless permanent magnet machines are used because of their high torque density. However, to the best of our knowledge, a process to set the previously reported; likewise, which rotor topology exhibits the best performance in such cases has not been validated. Consequently, the resulting actuator could exhibit suboptimal dynamical performance and power conversion efficiency. Although some design processes have been formulated in the past for semiactive controllers (the damping is modified using a variable resistive load), they are not suitable for active suspension control. Similarly, there are existing solutions to increase conversion efficiency using mechanical motion rectifiers; however, active forces cannot be exerted, limiting their applicability to semiactive actuators. Therefore, this paper presents a design methodology, using finite element method together with MATLAB/Simulink™, to set and test the parameters of AC brushless PM machines, intended for actively controlled suspensions. A novel approach to set the base speed, which takes advantage of field-weakening capability, is also presented. To test the proposed method, three machines with well-known rotor topologies were designed and evaluated as case studies, and the surface-mounted topology was found to be the most suitable for the analyzed task.

On-slope pilot testing of snow tubes was conducted at two ski areas in the United States to examine the effects of deceleration mats. Snow tube and rider kinematics were measured using an instrumented bodysuit and a GPS system worn by the rider. For each test, the riders descended a tubing run with minimal input and stopped in the run-out area. Snow tube and rider speeds when entering the run-out area were controlled to be approximately 9.5 m/s. Test trials were conducted with and without deceleration mats. Four deceleration mat conditions were tested, including two raised surface protuberances (ribs and projections) and two mat geometry parameters (flat and folded). The deceleration and effective coefficient of friction (COF) were determined for each trial. Data were recorded for 75 test trials with a mean (± standard deviation) speed entering the run-out area of 9.5 (±1.8) m/s. There were no significant differences in the deceleration or effective coefficient of friction between the surface protuberance conditions. The peak deceleration and effective COF for the folded mats (5.1 ± 1.6 m/s2 and 0.26 ± 0.14) was greater than for the flat (3.3 ± 0.8 m/s2 and 0.10 ± 0.07) and no mat (0.06 ± 0.3 m/s2 and 0.08 ± 0.03) conditions (all p < 0.05). Deceleration mats in run-out areas slow snow tube riders faster than without deceleration mats. Folding the deceleration mats produced greater deceleration but did not produce significantly different kinematics for the riders.

To reduce the risk of injury, waterski bindings should secure the foot to the ski when the likelihood of lower leg injury is low (retention) and free the foot when the likelihood of injury is high (release). Unlike snow skiing, there are no standards dictating the release of waterski bindings. Testing was completed to determine release torques in forward lean of three commercially available waterski boot-binding systems. Each binding was mounted to a 66-inch waterski and the boot was fitted on a lower leg surrogate with a torque transducer. A forward-lean bending moment was applied quasi-statically about the transverse axis of the ski until the binding released the boot. For the three boot-binding systems, the range of release torques were 126 to 219, 50 Nm to 141, and 63 to 127 Nm.

Purpose Primary ciliary dyskinesia (PCD) is characterised by repeated upper and lower respiratory tract infections, neutrophilic airway inflammation and obstructive airway disease. Different ultrastructural ciliary defects may affect lung function decline to different degrees. Lung clearance index (LCI) is a marker of ventilation inhomogeneity that is raised in some but not all patients with PCD. We hypothesised that PCD patients with microtubular defects would have worse (higher) LCI than other PCD patients. Methods Spirometry and LCI were measured in 69 stable patients with PCD. Age at testing, age at diagnosis, ethnicity, ciliary ultrastructure, genetic screening result and any growth of Pseudomonas aeruginosa was recorded. Results Lung clearance index was more abnormal in PCD patients with microtubular defects (median 10.24) than those with dynein arm defects (median 8.3, p = 0.004) or normal ultrastructure (median 7.63, p = 0.0004). Age is correlated with LCI, with older patients having worse LCI values (p = 0.03, r = 0.3). Conclusion This study shows that cilia microtubular defects are associated with worse LCI in PCD than dynein arm defects or normal ultrastructure. The patient's age at testing is also associated with a higher LCI. Patients at greater risk of obstructive lung disease should be considered for more aggressive management. Differences between patient groups may potentially open avenues for novel treatments., Author(s): S. Irving [sup.1] [sup.2] , M. Dixon [sup.1] , M. R. Fassad [sup.3] [sup.4] , E. Frost [sup.1] [sup.2] , J. Hayward [sup.3] [sup.5] , K. Kilpin [sup.2] , [...]

In the Western world, most 5-year-old children begin their formal schooling, and do so with diverse proficiencies. A common aim is for teachers to quickly evaluate their proficiencies to identify strengths and gaps, and then begin the teaching of reading and number. This article reports two studies into the item and structural characteristics of a well used instrument administered in the first 6-8 weeks of the students' school experience. The School Entry Assessment Kit consists of "Concepts about Print" (CAP) measure of early literacy, "Tell Me" procedures for oral language and story retelling, and "Checkout" game for early number knowledge and ability. The first study reviews the properties of these tests, and the second study relates the performance on the SEA with performance 1 and 5 years later. Implications for measuring progress, reviewing the tests, enhancing reporting, and reducing administration time are discussed.

This qualitative study explored the beliefs of students, parents and teachers on the purposes of schooling in order to provide a context for understanding beliefs and attitudes to school learning and achievement. Focus groups were conducted with Year 9 and 10 students (aged 13-15 years) and parents and teachers in three secondary schools in different socio-economic areas in an urban district. Four categories were identified in relation to beliefs about the purposes of schooling: (1) to learn and gain self-knowledge; (2) to develop life and social skills; (3) to optimize life chances and quality of life; (4) to enable future employment and economic wellbeing. Comparisons revealed that students, parents and teachers all believed in the learning purpose of schooling, but did not all endorse an economic purpose. Students had the broadest views on school purposes. The greatest alignment between views was found for students and parents. The greatest difference between groups was found for students and teachers from high socio-economic area schools. Findings were considered in relation to national curriculum aims and external pressures from globalization. Overall, findings are conducive to a lifelong learning approach, pointing to belief in the intrinsic value of school learning independent of any economic function it may serve.