Physical component analysis of galaxy cluster weak gravitational lensing data

We present a novel approach for reconstructing the projected mass distribution of clusters of galaxies from sparse and noisy weak gravitational lensing shear data. The reconstructions are regularised using knowledge gained from numerical simulations of clusters: trial mass distributions are constructed from N physically-motivated components, each of which has the universal density profile and characteristic geometry observed in simulated clusters. The parameters of these components are assumed to be distributed \emph{a priori} in the same way as they are in the simulated clusters. Sampling mass distributions from the components' parameters' posterior probability density function allows estimates of the mass distribution to be generated, with error bars. The appropriate number of components is inferred from the data itself via the Bayesian evidence, and is typically found to be small, reflecting the quality of the simulated data used in this work. Ensemble average mass maps are found to be robust to the details of the noise realisation, and succeed in recovering the input mass distribution (from a realistic simulated cluster) over a wide range of scales. We comment on the residuals of the reconstruction and their implications, and discuss the extension of the method to include strong lensing information.Comment: 12 pages, 7 figure

Health and well-being implications surrounding the use of wearable GPS devices in professional rugby league: A Foucauldian disciplinary analysis of the normalised use of a common surveillance aid

Wearable GPS tracking devices have become commonplace coaching aids across professional field sports to enhance sports performances and reduce injury rates, despite the implications of the technology being poorly understood. This study looked at how GPS devices are used and the impact constant surveillance has upon the physical, psychological, and emotional health of rugby football workers. The disciplinary analysis of Michel Foucault was used to investigate how British Super League teams use wearable GPS technology, to investigate the dominant 'truth' that promotes surveillance technologies as 'universally beneficial' to athlete sports performance, health and well-being. Data was drawn from semi-structured interviews with three performance analysts/strength and conditioning coaches at three different Super League clubs across the North of England. Participants confessed data generated from wearable GPS is often totally ignored, despite being specifically produced to protect athlete health and wellbeing. When used, GPS data can become a 'disciplinary tool' to normalise and coerce players to comply with potentially unhealthy physical and psychological demands of a professional playing career. Importantly, regardless of how GPS data was used, the employment of wearable GPS devices was constantly and rigorously implemented. The constant surveillance experience by working players, when mismanaged or adopted as a coercive disciplinary tool, magnifies the uncertainty and fear of failure central to the predominant challenges that arise during a working football career. This leads to the acceptance of problematic norms damaging to physical, psychological, and emotional health. If GPS or other surveillance based performance analysis technologies are to be used in sport, coaches need to regulate or re-think their day-to-day use to avoid creating new harms to athlete health and well-being

Complex training: The effect of exercise selection and training status on postactivation potentiation in rugby league players

This study compared the postactivation potentiation (PAP) response of the hex bar deadlift (HBD) and back squat (BS) exercises. The PAP response between different levels of athletes was also compared. Ten professional and 10 amateur rugby league players performed 2 experimental sessions. Participants performed a countermovement jump (CMJ) before and 2, 4, 6, 8, 10, 12, 14, and 16 minutes after a conditioning activity (CA) that contained 1 set of 3 repetitions at 93% 1 repetition maximum of either HBD or BS. A force platform determined peak power output (PPO), force at PPO, velocity at PPO, and jump height of each CMJ. Surface electromyography (EMG) of the vastus lasteralis, rectus femoris, tibialis anterior, and gastrocnemius medialis of each participant's dominant leg was recorded during each CMJ. A further 10 participants performed a control trial without a CA. The HBD expressed PAP between 2 and 6 minutes post-CA, whereas the BS did not. The HBD exhibited a significantly (p ≤ 0.05) greater PAP response than the BS for PPO. There were no significant (p > 0.05) differences between stronger and weaker players. There were no significant (p > 0.05) changes in the EMG variables. These results suggest that HBD is a suitable CA for eliciting PAP in stronger and weaker athletes. Strength and conditioning coaches should consider the CA and time frame between the CA and the plyometric exercise for optimal PAP responses

Combining internal- and external-training-load measures in professional rugby league

Purpose: This study investigated the effect of training mode on the relationships between measures of training load in professional rugby league players. Methods: Five measures of training load (internal: individualized training impulse, session rating of perceived exertion; external—body load, high-speed distance, total impacts) were collected from 17 professional male rugby league players over the course of two 12-week pre-season periods. Training was categorized by mode (small-sided games, conditioning, skills, speed, strongman, and wrestle) and subsequently subjected to a principal component analysis. Extraction criteria were set at an eigenvalue of greater than one. Modes that extracted more than one principal component were subjected to a varimax rotation. Results: Small-sided games and conditioning extracted one principal component, explaining 68% and 52% of the variance, respectively. Skills, wrestle, strongman, and speed extracted two principal components explaining 68%, 71%, 72%, and 67% of the variance respectively. Conclusions: In certain training modes the inclusion of both internal and external training load measures explained a greater proportion of the variance than any one individual measure. This would suggest that in those training modes where two principal components were identified, the use of only a single internal or external training load measure could potentially lead to an underestimation of the training dose. Consequently, a combination of internal and external load measures is required during certain training modes

Investigating the Use of Pair Programming for Teaching Data Structures and Algorithms

Incoming university students who have not previously studied computer programming often find it a challenging subject, leading to high failure rates (Williams & Upchurch, 2001). As a result, enrolment in computer science courses is declining (Carver et al., 2007), with the participation of female students being particularly affected (Werner, Hanks & McDowell, 2004). Research has suggested that the lack of a formalized structure for collaborative learning may be one of the factors responsible for students’ negative impressions of computer science (Werner et al., 2004). In this study we investigated whether the use of pair programming in labs would facilitate peer learning and enhance students’ confidence in their programming ability. The hypothesis motivating this intervention was that the more experienced programmers would transmit some of their knowledge to the weaker students and that the class as a whole would benefit from having the support of a partner to identify problem solving strategies and to resolve coding bugs. Results showed that the intervention was generally well received, although the weaker programmers were more positive about it than the stronger ones. Students that reported learning from pair programming were less likely to enjoy programming (r = -.496), less likely to enjoy labs (r = -.502), more likely to struggle with understanding lab material (r = .561) and more likely to report a lack of confidence in programming (r = -.415). Although there was no significant increase in final exam grades for male students, there was a significant 9.7% increase for female students. The most frequently reported positive feature of pair programming was that it allowed students to meet more people in the class

I Wonder Who : Has Taken My Place With You

https://digitalcommons.library.umaine.edu/mmb-vp/3903/thumbnail.jp

The effect of accommodating resistance on the post-activation potentiation response in Rugby League players

This study examined the post-activation potentiation (PAP) response of two conditioning activities (CA), the hexbar deadlift (HBD) and back squat (BS), combined with accommodating resistance; this adds a percentage of the total resistance during the exercise. Twenty amateur rugby league players performed two experimental trials and a control trial without a CA. Participants performed a countermovement jump (CMJ) before and 30, 90, and 180 seconds after one set of three repetitions of each CA at 70% 1 repetition maximum (RM), with up to an additional 23% 1RM from accommodating resistance. Peak power output (PPO), force at PPO, velocity at PPO and jump height were calculated for each CMJ. Surface electromyography (EMG) of the vastus lasteralis (VL), rectus femoris (BF), tibialis anterior (TA), and gastrocnemius medialis (GM) were also measured. Repeated-measures analysis of variance revealed no significant (p > 0.05) PAP response for either exercise condition when comparing CMJ variables to baseline values, nor were there any significant (p > 0.05) differences between exercise conditions. However, individualized recovery intervals (baseline vs. maximum potentiation response) demonstrated significant (p ≤ 0.05) improvements in PPO (3.99 ± 4.99%), force at PPO (4.87 ± 6.41%), velocity at PPO (4.30 ± 5.86%), jump height (8.45 ± 10.08%), VL EMG (20.37 ± 34.48%), BF EMG (22.67 ± 27.98%), TA EMG (21.96 ± 37.76%) and GM EMG (21.89 ± 19.65%). Results from this study must be interpreted with caution; however, it is conceivable that athletic performance can be acutely enhanced when complex training variables are individualized

Experiences of using mobile technologies and virtual field tours in Physical Geography: implications for hydrology education

Education in hydrology is changing rapidly due to diversification of students, emergent major scientific and practical challenges that our discipline must engage with, shifting pedagogic ideas and higher education environments, the need for students to develop new discipline specific and transferrable skills, and the advent of innovative technologies for learning and teaching. This paper focuses on new technologies in the context of learning and teaching in Physical Geography and reflects on the implications of our experiences for education in hydrology. We evaluate the experience of designing and trialling novel mobile technology-based field exercises and a virtual field tour for a Year 1 undergraduate Physical Geography module at a UK university. The new exercises are based on using and obtaining spatial data, operation of meteorological equipment (explained using an interactive DVD), and include introductions to global positioning systems (GPS) and geographical information systems (GIS). The technology and exercises were well received in a pilot study and subsequent rolling-out to the full student cohort (∼150 students). A statistically significant improvement in marks was observed following the redesign. Although the students enjoyed using mobile technology, the increased interactivity and opportunity for peer learning were considered to be the primary benefits by students. This is reinforced further by student preference for the new interactive virtual field tour over the previous "show-and-tell" field exercise. Despite the new exercises having many advantages, exercise development was not trivial due to the high start-up costs, the need for provision of sufficient technical support and the relative difficulty of making year-to-year changes (to the virtual field tour in particular). Our experiences are highly relevant to the implementation of novel learning and teaching technologies in hydrology education