Validation of a videogrammetry technique for analysing American football helmet kinematics

ABSTRACT

Professional American football games are recorded in digital video with multiple cameras, often at high resolution and high frame rates. The purpose of this study was to evaluate the accuracy of a videogrammetry technique to calculate translational and rotational helmet velocity before, during and after a helmet impact. In total, 10 football impacts were staged in a National Football League (NFL) stadium by propelling helmeted 50th percentile male crash test dummies into each other or the ground at speeds and orientations representative of concussive impacts for NFL players. The tests were recorded by experienced sports film crews to obtain video coverage and quality typically available for NFL games. A videogrammetry procedure was used to track the position and rotation of the helmet throughout the relevant time interval of the head impact. Compared with rigidly mounted retroreflective marker three dimensional (3-D) motion tracking that was concurrently collected in the experiments, videogrammetry accurately calculated changes in translational and rotational velocity of the helmet using high frame rate (two cameras at 240 Hz) video (7% and 15% error, respectively). Low frame rate (2 cameras at 60 Hz) video was adequate for calculating pre-impact translational velocity but not for calculating the translational or rotational velocity change of the helmet during impact.     

Building student-teacher relationships and improving behaviour-management for classroom teachers

Teachers can at times view behavioural intervention procedures as time-consuming. Thus, socially-valid classroom-based interventions are a critical component to behavioural success. This study examined the effects of traditional behavioural interventions with two kindergarten students presenting with challenging behaviours, including aggression, tantrums and noncompliance. Notably, it was found that traditional behavioural procedures were not sufficient to substantially reduce the behaviours alone. Therefore, a relationship-building component was added to target positive student-teacher relationships. Student outcomes resulted in a significant reduction in challenging behaviour as well as teacher-reported behaviours showing a reduction across all measured periods. Ongoing teacher consultation, increased student-teacher relationships (STRs) and use of effective classroom management strategies are necessary for effective models of behaviour support.     

Exploring Dialectical Tensions of Leading Volunteers in Two Community Choirs

Leaders of volunteers face different challenges than leaders of paid employees due to different motivations and reward expectations. After synthesizing previous research applying dialectical theory to group members or leaders, this study examines the dialectical tensions that leaders of volunteers experienced and the communication they used to manage those tensions as reported by both the leaders and the volunteers. A constant-comparison method was used to analyze observations and interviews of members and leaders of two community choirs. The findings suggest that leaders of volunteers face eight dialectical tensions representing three broad categories: (a) task and relationship; (b) process and outcome; and (c) internal and external. Leaders negotiated these dialectical tensions through communication strategies including use of humor and appeals to artistic spirituality. These strategies represent hybridization and dualistic discourse rather than a monologic emphasis of one course of action over another.     

A New Student Learning Focus for the Academic Library: From Geographical Proximity of the Learning Commons to Organizational Proximity within the Library

In 2015, student learning programs at the University of Saskatchewan moved organizationally to the university library. While these services resided physically in the library as part of the Learning Commons partnership, this recent change presents the library with a new focus and responsibility for broader student learning support and academic skill development. Highlighting examples of organizational integration of student learning support, this article uses a proximity perspective, suggesting that geographical proximity of services in the learning commons does not go far enough to achieve the deeper collaboration and integration necessary for holistic and integrated learning, and that organizational proximity is needed.     

Investigating Students’ Learning Through Co-designing with Technology

Involving students in the co-design of educational curricula and practices can benefit both students and teachers. Students who participate in co-design may show better learning or increased agency or engagement. In the present study, we investigated what kind of science knowledge or practices can be learned by student co-designers while engaging in co-design practices and how that learning happens with six high school students. We created a model to guide the analysis of students’ learning with technology in co-designing processes. The results revealed that students learned engineering design process even if no explicit instruction on engineering learning was given. Also, our analysis suggested that co-designing with technology enabled learning of the engineering design process and potentially furthered learning of science because it promoted knowledge integration. The results have implications for understanding and enhancing engineering design and science learning through co-designing with technology.