Static and dynamic accuracy of a magnetic-inertial measurement unit used to provide racket swing kinematics

Magnetic-inertial measurement units (MIMUs) are becoming more prevalent in sports biomechanics and may be a viable tool to evaluate kinematic parameters. This study examined the accuracy of a MIMU to estimate orientation angles under static conditions and dynamically from a squash racket during a forehand drive shot. A MIMU was mounted onto a goniometer and moved through 0–90°, with static data collected at 10° increments during 10 repetitions of all three axes. Typical error analyses showed the MIMU to be very reliable (TE ≤ 0.03°). MIMU accuracy was determined via intraclass correlation coefficients (ICC) (r > 0.999, p < 0.001). An ordinary least products regression showed no proportional bias and minimal fixed bias for all axes. Dynamic accuracy was assessed by comparing MIMU and optical motion capture data of squash racket swing kinematics. A MIMU was fixed onto a racket and 10 participants each hit 10 forehand shots. Mean orientation angle error at ball impact was <0.50° and ICC showed very high correlations (r ≥ 0.988, p < 0.001) for all orientations. Swing phase root mean squared errors were ≤2.20°. These results indicate that a MIMU could be used to accurately and reliably estimate selected racket swing kinematics.     

Extreme Programming: The Student View

Students in two offerings of a software engineering course were asked to write opinion papers regarding the use of Extreme Programming (XP) in an undergraduate computer science curriculum. The majority opposed the use of XP as the preferred life-cycle model for the project in that course, but they did support introducing some of the practices of XP in selected courses. They felt that unit testing and coding standards should become part of the introductory programming courses, but other practices should be deferred to specific project-oriented courses, or not introduced at all. Two pilot studies provided additional insights that are consistent with the students' opinions.     

Two- and Three-Year Achievement Results From the Memphis Restructuring Initiative

The purpose of this study was to analyze student achievement data from the first 3 years of the Memphis Restructuring Initiative (MRI). The MRI represents one of the first efforts by an urban school district to move past traditional top-down versus bottom-up reform debates by providing systemic support for outside-in/inside-out implementation and local co-construction of externally-developed reform designs in schools. Analyses of academic achievement focus on a state-of-the-art measure of value added assessments. At the end of 3 years the reforming schools had produced generally positive gains relative to locally matched control schools. Those results varied somewhat by reform type and by level of poverty in the communities being served. Based on the research methods used and the results, implications for future research and practice in educational reform are discussed.     

Small Robot Projects: Before You Start

Working with robots is an attractive possibility for educators at many levels. The price and availability of robotic hardware are favorable, there are often examples in the media of school groups doing robotic projects, and the projects support group design and co-operative activity. Still, these projects cannot be organized without considerable effort. In this article, we look at some of the opportunities and pitfalls that are encountered when working with robots in an educational setting, illustrating them with anecdotes from our experience with eight small robot-building projects, with participants ranging in age from nine to adult, and duration ranging from a single day to a full semester. We suggest some of the benefits of these projects and outline the problems organizers and participants will be likely to face.     

Technique and timing in women's inward two and one half somersault tuck (405C) and the men's inward two and one half somersault pike (405B) 3 m springboard dives

The purpose of this study was to compare the inward two and one half somersault dive in a tuck position (405C) performed by females (n = 22) and the inward two and one half somersault dive in a pike position (405B) performed by males (n = 24) to determine changes required by females to successfully perform 405B. Key performance variables in inward dives were also compared to those of backward dives. Video data of the dives performed at the 1999 FINA World Diving Cup were captured and digitized to obtain times and postures of the divers at specific events including takeoff and entry. Estimates of flight height and mass-normalised work done on the springboard were obtained from flight times. Some females worked the springboard strongly enough to generate sufficient height and rotation to perform 405B. Males performed 405B comfortably because they achieved better height and rotation than the females. A comparison of backward and inward dives revealed that divers are able to attain greater height in backward dives than inward dives.     

Les graphes de flux dans l'enseignement secondaire

Sans résuméTravail effectué dans le cadre du groupe de recherche en didactique de la mathématique du Conseil National des Recherches.     

John A. Stormer and the Hofstadter hypothesis

Does political rhetoric hold the key to an understanding of political pathology? Blending historical scholarship and behavioral research, this study tested empirically hypotheses derived from Richard Hofstadter's model of the “paranoid style” in American politics. The data were drawn from John A. Stormer's None Dare Call It Treason.     

The ethical status of non-commercial spam

Much attention has been given in recent years to the moral status of commercial spam. Less attention has been focused on newer, non-commercial varieties of spam, such as spam from political parties, community sector organizations and governments. This article makes a start on evaluating the moral status of these non-commercial varieties of spam, drawing on arguments used to evaluate commercial spam.