Kayaking and wagging of liquid crystals under shear: Comparing director and mesogen motions

Rod-like colloids in dense solutions perform collective orientational motions under shear flow. The periodic tumbling motions of the director, i.e. the average orientation of the rods, are commonly characterized as kayaking, wagging and flow-aligning, in order of increasing shear rate. Our event-driven Brownian dynamics simulations of rigid spherocylinders reproduce these three distinct director motions, but also clearly show, for the first time, that the individual mesogens are kayaking at all shear rates. The synchrony of the mesogens's motions gradually decreases with increasing shear rate, which at a critical shear rate causes a transition of the apparent collective motion from kayaking to wagging. The rods's persistent kayaking also explains the continuity of the tumbling period at this transition and the smooth change from wagging to flow-aligning observed at higher shear rates

An introduction to the constraints-led approach to learning in outdoor education

Participation in outdoor education is underpinned by a learner's ability to acquire skills in activities such as canoeing, bushwalking and skiing and consequently the outdoor leader is often required to facilitate skill acquisition and motor learning. As such, outdoor leaders might benefit from an appropriate and tested model on how the learner acquires skills in order to design appropriate learning contexts. This paper introduces an approach to skill acquisition based on ecological psychology and dynamical systems theory called the constraints-led approach to skills acquisition. We propose that this student-centred approach is an ideal perspective for the outdoor leader to design effective learning settings. Furthermore, this open style of facilitation is also congruent with learning models that focus on other concepts such as teamwork and leadership

Learning to Hash-tag Videos with Tag2Vec

User-given tags or labels are valuable resources for semantic understanding of visual media such as images and videos. Recently, a new type of labeling mechanism known as hash-tags have become increasingly popular on social media sites. In this paper, we study the problem of generating relevant and useful hash-tags for short video clips. Traditional data-driven approaches for tag enrichment and recommendation use direct visual similarity for label transfer and propagation. We attempt to learn a direct low-cost mapping from video to hash-tags using a two step training process. We first employ a natural language processing (NLP) technique, skip-gram models with neural network training to learn a low-dimensional vector representation of hash-tags (Tag2Vec) using a corpus of 10 million hash-tags. We then train an embedding function to map video features to the low-dimensional Tag2vec space. We learn this embedding for 29 categories of short video clips with hash-tags. A query video without any tag-information can then be directly mapped to the vector space of tags using the learned embedding and relevant tags can be found by performing a simple nearest-neighbor retrieval in the Tag2Vec space. We validate the relevance of the tags suggested by our system qualitatively and quantitatively with a user study

Risk taking in Extreme Sports: A phenomenological perspective

Participation in extreme sports is enjoying incredible growth while more traditional recreational activities such as golf are struggling to maintain numbers. Theoretical perspectives on extreme sports and extreme sport participants have assumed that participation is about risk-taking. However, these theory-driven methodologies may reflect judgments that do not necessarily relate to participants' lived experience. In this paper I review current risk-oriented perspectives on extreme sports and present research findings that question this assumed relationship between extreme sports and risk and thus reposition the experience in a hitherto unexplored manner. Risk taking is not the focus. Participants acknowledge that the potential outcome of a mismanaged mistake or accident could be death. However, accepting this potential outcome does not mean that they search for risk. Participants argue that many everyday life events (e.g., driving) are high-risk events. Participants undertake detailed preparation in order to minimise the possibility of negative outcomes because extreme sports trigger a range of positive experiential outcomes. The study is significant as it followed a hermeneutic phenomenological process which did not presuppose a risk-taking orientation. Hermeneutic phenomenology allows for a multitude of data sources including interviews (10 male and 5 female extreme sports participants, ages 30 to 72 years), auto-biographies, videos and other firsthand accounts. This process allowed this unexpected perspective to emerge more clearly

A biomechanical analysis of the stand-up paddle board stroke: A comparative study

Background: Stand-up paddle boarding (SUP) is a rapidly growing global aquatic sport, with increasing popularity among participants within recreation, competition and rehabilitation. To date, few scientific studies have focused on SUP. Further, there is no research examining the biomechanics of the SUP paddle stroke. The purpose of this study was to investigate whether variations in kinematics existed among experienced and inexperienced SUP participants using three-dimensional motion analysis. This data could be of significance to participants, researchers, coaches and health practitioners to improve performance and inform injury minimization strategies. Methods: A cross-sectional observational design study was performed with seven experienced and 19 inexperienced paddlers whereby whole-body kinematic data were acquired using a six-camera Vicon motion capture system. Participants paddled on a SUP ergometer while three-dimensional range of motion (ROM) and peak joint angles were calculated for the shoulders, elbows, hips and trunk. Mann-Whitney U tests were conducted on the non-normally distributed data to evaluate differences between level of expertise. Results: Significant differences in joint kinematics were found between experienced and inexperienced participants, with inexperienced participants using greater overall shoulder ROM (78.9° ± 24.9° vs 56.6° ± 17.3°, p = 0.010) and less hip ROM than the experienced participants (50.0° ± 18.5° vs 66.4° ± 11.8°, p = 0.035). Experienced participants demonstrated increased shoulder motion at the end of the paddle stoke compared to the inexperienced participants (74.9° ± 16.3° vs 35.2° ± 28.5°, p = 0.001 minimum shoulder flexion) and more extension at the elbow (6.0° ± 9.2° minimum elbow flexion vs 24.8° ± 13.5°, p = 0.000) than the inexperienced participants. Discussion: The results of this study indicate several significant kinematic differences between the experienced and inexperienced SUP participants. These variations in technique were noted in the shoulder, elbow and hip and are evident in other aquatic paddling sports where injury rates are higher in these joints. These finding may be valuable for coaches, therapists and participants needing to maximize performance and minimize injury risk during participation in SUP.Full Tex

RiVAS and RiVAS+: Opportunities for Application of a Multi-Criteria River Value Assessment System Approach which Considers Existing and Potential States

The River Values Assessment System (RiVAS) uses a combination of expert panels and multi criteria analysis to identify primary attributes (or main features) of river values (e.g., whitewater kayaking, native birds) and their key indicators. The resulting data set is used to rank rivers for their existing (instream) and potential (out-of-stream) significance. The RiVAS method has been applied to seven values and tested across a range of councils with most focus in Tasman District. The tool has demonstrated utility and is very cost effective to implement. Further development has now led to RiVAS+ to consider potential significance for instream values, using the same attributes and indicators, and also identifying the interventions needed to achieve these potential future states (e.g., water quality improvements, willow removal, increased flows). RiVAS+ enables instream uses to be considered on the same basis as out-of-stream opportunities. RiVAS+ can be undertaken more-or-less concurrently with RiVAS and enables a range of applications. First, it allows decision makers to gain an understanding of the difference between existing relative importance or significance of a value and its potential (if restored or developed). Second, it enables better evaluation of potential restoration or development options in a range of circumstances including where water resource development is planned. Finally, with further input it might be possible to quantify the cost of the interventions which would then allow better consideration of mitigation and other options in resource management policy and decision making processes. In this paper we demonstrate the method and the opportunities.River values, prioritisation system, existing and potential, interventions, New Zealand, Environmental Economics and Policy,

A Wholesome Learning Experience

2017 essay contest winner Danielle Nurmi\u27s A Wholesome Learning Experienc

Epidemiology of injuries in stand-up paddle boarding

Background: Stand-up paddle boarding (SUP) is a recreational activity and sport that has grown exponentially, with participation increasing from 1.1 million in 2010 to 2.8 million in 2014 in the United States alone. Despite this growth in participation, SUP remains underresearched with regard to injury epidemiology. Purpose: To investigate injury epidemiology (severity, location, type, mechanism) in SUP. Study Design: Descriptive epidemiology study. Methods: An open-source online survey was administered to active SUP participants internationally. The survey captured information relevant to demographics, participation, and injury history over the past 12 months. Results: Of 240 participants included in the data analysis, 67.1% were males, and 54.6% were involved in competition. Participants spent a mean 192.6 ± 179.5 hours participating in SUP per year, most commonly for fun and fitness (43.3%) at the beach or bay (63.0%). A total of 95 participants had sustained at least 1 injury. A total of 161 injuries were recorded, resulting in an injury rate of 3.63 (95% CI, 3.04-4.16) per 1000 hours of SUP. The shoulder/upper arm was the most frequently injured body location, accounting for 32.9% of all injuries, followed by the lower back (14.3%) and the elbow/forearm (11.8%). The most common injury types were to muscle/tendon (50.4%), joint/ligament (22.6%), and skin (14.2%). Endurance paddling was the most frequently reported mechanism of injury (34.5%), followed by contact with a paddler’s own board (20.1%) and sprint paddling (9.3%). Key risk factors for sustaining an injury were age &gt;46 years, competitive status, and participating for &gt;4.8 hours/week, as well as using SUP for racing. Conclusion: This is the first study to report injury epidemiology for SUP. It is evident that both sexes participate in SUP for fun, fitness, and competition. With regard to injuries, the shoulder, lower back, and elbow are the most injury prone; older age, competitive status, and longer hours of participation all influenced the chance of injury. Findings from this study provide the foundation for injury prevention strategies. </jats:sec