Average of trial peaks versus peak of average profile: impact on change of direction biomechanics

ABSTRACT

The aims of this study were twofold: firstly, to compare lower limb kinematic and kinetic variables during a sprint and 90° cutting task between two averaging methods of obtaining discrete data (peak of average profile vs. average of individual trial peaks); secondly, to determine the effect of averaging methods on participant ranking of each variable within a group. Twenty-two participants, from multiple sports, performed a 90° cut, whereby lower limb kinematics and kinetics were assessed via 3D motion and ground reaction force (GRF) analysis. Six of the eight dependent variables (vertical and horizontal GRF; hip flexor, knee flexor, and knee abduction moments, and knee abduction angle) were significantly greater (p ≤ 0.001, g = 0.10–0.37, 2.74–10.40%) when expressed as an average of trial peaks compared to peak of average profiles. Trivial (g ≤ 0.04) and minimal differences (≤ 0.94%) were observed in peak hip and knee flexion angle between averaging methods. Very strong correlations (ρ ≥ 0.901, p < 0.001) were observed for rankings of participants between averaging methods for all variables. Practitioners and researchers should obtain discrete data based on the average of trial peaks because it is not influenced by misalignments and variations in trial peak locations, in contrast to the peak from average profile.     

Mobile consumers and the retail industry: the resistible advent of a new marketing scene

ABSTRACT

Over the last ten years, marketing professionals have invested in various devices aimed at digitalizing the point of sale. Mobile phones, and the connection they open between the digital and physical worlds, are likely to profoundly renew the way organizations build the representations of consumers upon which they operate. This article aims to describe the new, mobile-based market infrastructure that is currently being implemented; the figures of the consumer it builds on and renews for marketing purposes; and the opportunities it offers to create a new marketing scene. We address this question by focusing on the world of physical retail. We show that online commerce websites and http cookies have enabled a connection between three traditionally separate figures of the consumer and associated marketing scenes: the consumer as an audience, as a shopping cart, or as a (loyalty) card. The smartphone carries the promise of pursuing this movement into store aisles. We show, however, that the domestication of physical geography to cultivate mobile consumers is particularly difficult, and so far based on a series of disparate attempts and experiments.     

An Expert System Helps Students Learn Database Design

Teaching and learning database design is difficult for both instructors and students. Students need to solve many problems with feedback and corrections. A Web‐based specialized expert system was created to enable students to create designs online and receive immediate feedback. An experiment testing the system shows that it significantly enhances student learning. The system also provides a more neutral learning environment in terms of personal factors such as gender and prior class work.     

体育运动中的内部动机——认知评价理论的解释

认知评价理论认为,内部动机以人的能力需要和自我决策需要为基础,任何影响能力感和自我决策感的事件都可影响人的内部动机。象奖金、奖品一类的外部奖励由于其携带的控制性功能很强,往往会对内部动机产生破坏性影响。如果一项活动可提高人的能力感并满足人的自我决策需要,这一活动就因其携带的信息性功能十分突出而加强内部动机。     

An exper iment with research data

The editor wishes to congratulate Tom Brown on his election as the incoming President of IASSIST. Correspondence regarding this column should be addressed to him at :Administrative Staff, Office of the National Archives, Washington DC 20408]