Accuracy between optical and inertial motion capture systems for assessing trunk speed during preferred gait and transition periods

Motion capture through inertial sensors is becoming popular, but its accuracy to describe kinematics during changes in walking speed is unknown. The aim of this study was to determine the accuracy of trunk speed extracted using an inertial motion system compared to a gold standard optical motion system, during steady walking and stationary periods. Eleven participants walked on pre-established paths marked on the floor. Between each lap, a 1-second stationary transition period at the initial position was included prior to the next lap. Resultant trunk speed during the walking and transition periods were extracted from an inertial (240 Hz sampling rate) and an optical system (120 Hz sampling rate) to calculate the agreement (Pearson’s correlation coefficient) and relative root mean square errors between both systems. The agreement for the resultant trunk speed between the inertial system and the optical system was strong (0.67 < r ≤ 0.9) for both walking and transition periods. Moreover, relative root mean square error during the transition periods was greater in comparison to the walking periods (>40% across all paths). It was concluded that trunk speed extracted from inertial systems have fair accuracy during walking, but the accuracy was reduced in the transition periods.     

Formal and informal interorganizational learning within strategic alliances

Learning behaviors of employees can be either formalized (in the form of programmed events and visits) or informal (in the form of spontaneous interaction and knowledge sharing). We investigate the effect that both types of learning behaviors have on interorganizational learning of substantive knowledge in the context of an alliance. We also look at the effects that the two forms of learning behavior have on each other. We find that while informal learning behaviors have a consistently positive effect on the learning outcome and on formal learning behaviors, this is not so for formal learning behaviors. The effect of formal behaviors on both learning outcome and informal behaviors, while positive, diminishes at higher levels. This leads us to conclude that although both informal and formal learning behaviors foster interorganizational learning, too much formalization obstructs learning. Similarly, while formally programmed behaviors do encourage informal learning behaviors of the boundary spanners, an excess of formalization stifles them.     

Editorial introduction

Editorial introduction     

Research on education in developing countries: An inventory of Dutch projects and programmes

This paper surveys both past and present research on education in developing countries that has been undertaken by Dutch researchers. It classifies the research according to whether it has been concerned with formal, non-formal or informal education; examines different sources of funding; and the types of collaborative ventures involved. It also attempts to evaluate different types of programme, including private ventures, and highlights some of the major ‘bottlenecks’ which hamper research.     

Between-school variation in physical activity,aerobic fitness,and organized sports participation: A multi-level analysis

Abstract

A large proportion of a child's day is spent at school interacting with certain physical surroundings, teachers, and school friends. Thus, schools could have a marked impact on establishing physical activity habits. The aim of the present study was to assess between-school variation in physical activity, aerobic fitness, and organized sports participation. Altogether, we tested 1766 nine- and fifteen-year-old children attending 242 school classes at 35 different schools in Denmark in 1997–2003. The intra-class correlation coefficient (ICC) for objectively assessed physical activity ranged between 0.06 and 0.18 depending on the dimension of physical activity and the time considered (i.e. school time vs. leisure time). For aerobic fitness, an ICC of 0.10 was observed, whereas that for organized sports participation ranged between 0.01 and 0.10 depending on the age group. Studying between-school variation in physical activity provides information about the extent to which children adjust their physical activity habits according to the social and environmental circumstances that they share, and helps to plan future school-based physical activity studies, especially in terms of sample size and power calculation.     

Reconsidering teachers’ pedagogical reasoning and decision making for technology integration as an agenda for policy,practice and research

Educational technology research and development - This article focuses on preservice and in-service teachers’ pedagogical reasoning, decision making and action concerning technology...     

Mapping mentor teachers’ roles in mentoring dialogues

This literature study deals with the issue of how to conceptualize the supervisory behaviour of mentor teachers in mentoring dialogues by systematically examining empirical literature on key aspects of mentor teachers’ behaviour during dialogues with prospective teachers. From the findings a model is derived which can be used to study mentor teachers’ behaviour in mentoring dialogues. The model may be helpful in the further development of the quality of mentor teachers’ behaviour in mentoring dialogues.     

Protein and cell patterning in closed polymer channels by photoimmobilizing proteins on photografted poly(ethylene glycol) diacrylate

Definable surface chemistry is essential for many applications of microfluidic polymer systems. However, small cross-section channels with a high surface to volume ratio enhance passive adsorption of molecules that depletes active molecules in solution and contaminates the channel surface. Here, we present a one-step photochemical process to coat the inner surfaces of closed microfluidic channels with a nanometer thick layer of poly(ethylene glycol) (PEG), well known to strongly reduce non-specific adsorption, using only commercially available reagents in an aqueous environment. The coating consists of PEG diacrylate (PEGDA) covalently grafted to polymer surfaces via UV light activation of the water soluble photoinitiator benzoyl benzylamine, a benzophenone derivative. The PEGDA coating was shown to efficiently limit the adsorption of antibodies and other proteins to <5% of the adsorbed amount on uncoated polymer surfaces. The coating could also efficiently suppress the adhesion of mammalian cells as demonstrated using the HT-29 cancer cell line. In a subsequent equivalent process step, protein in aqueous solution could be anchored onto the PEGDA coating in spatially defined patterns with a resolution of <15 μm using an inverted microscope as a projection lithography system. Surface patterns of the cell binding protein fibronectin were photochemically defined inside a closed microfluidic device that was initially homogeneously coated by PEGDA. The resulting fibronectin patterns were shown to greatly improve cell adhesion compared to unexposed areas. This method opens for easy surface modification of closed microfluidic systems through combining a low protein binding PEG-based coating with spatially defined protein patterns of interest.