Stepping out of the norm: an examination of praxis for a culturally‐relevant pedagogy for African‐American children

This paper examines two Anglo teachers' understanding of their praxis as they attempted to present a culturally‐relevant physical education programme to a class of African‐American 6^th‐grade students. In this case, the content was ‘stepping’, a branch of the African‐American vernacular dance tree. Five specific themes emerged: teacher apprehension; concerns about teacher legitimacy; resolution of apprehension and concerns; the unique nature of the content; and continual ethical uneasiness. The teachers expanded their understanding of praxis beyond thinking, acting, and reflecting to consider the political and social aspects that impact curriculum, pedagogy, and students.     

Protein sensing by nanofluidic crystal and its signal enhancement

Nanofluidics has a unique property that ionic conductance across a nanometer-sized confined space is strongly affected by the space surface charge density, which can be utilized to construct electrical read-out biosensor. Based on this principle, this work demonstrated a novel protein sensor along with a sandwich signal enhancement approach. Nanoparticles with designed aptamer onside are assembled in a suspended micropore to form a 3-dimensional network of nanometer-sized interstices, named as nanofluidic crystal hereafter, as the basic sensing unit. Proteins captured by aptamers will change the surface charge density of nanoparticles and thereby can be detected by monitoring the ionic conductance across this nanofluidic crystal. Another aptamer can further enlarge the variations of the surface charge density by forming a sandwich structure (capturing aptamer/protein/signal enhancement aptamer) and the read-out conductance as well. The preliminary experimental results indicated that human α-thrombin was successfully detected by the corresponding aptamer modified nanofluidic crystal with the limit of detection of 5 nM (0.18 μg/ml) and the read-out signal was enhanced up to 3 folds by using another thrombin aptamer. Being easy to graft probe, facile and low-cost to prepare the nano-device, and having an electrical read-out, the present nanofluidic crystal scheme is a promising and universal strategy for protein sensing.     

Effect of postural changes on 3D joint angular velocity during starting block phase

Abstract

Few studies have focused on the effect of posture during sprint start. The aim of this study was to measure the effect of the modification of horizontal distance between the blocks during sprint start on three dimensional (3D) joint angular velocity. Nine trained sprinters started using three different starting positions (bunched, medium and elongated). They were equipped with 63 passive reflective markers, and an opto-electronic Motion Analysis® system was used to collect the 3D marker trajectories. During the pushing phase on the blocks, norm of the joint angular velocity (NJAV), 3D Euler angular velocity (EAV) and pushing time on the blocks were calculated. The results demonstrated that the decrease of the block spacing induces an opposite effect on the angular velocity of joints of the lower and the upper limbs. The NJAV of the upper limbs is greater in the bunched start, whereas the NJAV of the lower limbs is smaller. The modifications of NJAV were due to a combination of the movement of the joints in the different degrees of freedom. The medium start seems to be the best compromise because it leads, in a short pushing time, to a combination of optimal joint velocities for upper and lower segments.     

Leg Muscle Metabolism in Trained and Untrained Men

The purpose of this study was to describe substrate changes in blood and muscles during submaximal exercise and to look at the relationship of these changes to some enzyme activities important in lipid and carbohydrate metabolism. A group of six trained and six untrained men were exercised for 1 hour at 50% [Vdot]O₂ max; three from each group cycled and the rest ran on a treadmill. During the exercise, blood-free fatty acid (FFA) levels increased twofold, glycerol by 3.6 times, triglyceride (TG) by 11/100 ml, and glucose by a mean 11 mg/100 ml in the trained men. In the untrained subjects, however, FFA increased 1.8 fold, glycerols 1.6 fold, and TG by a mean 24/100 ml. Glucose fell in every subject by an average 5 mg%. Muscle glycogen depletion averaged 34 mmoles/kg in the untrained and 23 mmoles/kg in the trained group. The activities of succinic acid dehydrogenase (SDH), malic acid dehydrogenase (MDH), and carnitine palmityl transferase (CPT) were greater by 177%, 93%, and 64%, respectively, in the trained group than in the untrained subjects. The results indicated that at the same percent [Vdot]O₂ max, the trained men seemed to “preferentially” use FFA as an energy source, possibly due to a well developed Krebs cycle and increased CPT activities. This preference would tend to inhibit the major rate-limiting enzymes of glycolysis, thus slowing even further the use of carbohydrates as an energy source. The differences in response to exercise were independent of fiber type and indicate that these catabolic responses were primarily due to aerobic training.     

Effects of Teaching Experience,Knowledge of Performer Competence,and Knowledge of Performance Outcome on Performance Error Identification

The purpose of this study was to determine if experienced tennis teachers could be differentiated from inexperienced tennis teachers on the basis of their ability to identify common performance errors in films depicting the performance of the tennis forehand. The study also sought to determine if the differences in error detection proficiency between the two groups would be greater when subjects were provided with preresponse information concerning the performer's level of competence in the skill (PCI) and postresponse information concerning the outcome produced by the response (POI). The error detection proficiency of 40 experienced tennis teachers and 40 undergraduate physical education students was assessed under conditions of PCI and POI present, PCI present and POI absent, PCI absent and POI present, and PCI and POI absent. Results indicated that the experienced teachers, although significantly more accurate in detecting errors than the novice teachers, were only marginally so. No positive effects on error detection accuracy were observed for PCI and the facilitative effects for POI tended to be small and generalized to both experienced and inexperienced subjects rather than being specifically helpful to the experienced teachers. The differences between experienced and inexperienced teachers appeared to be due to fewer false alarms committed by the experienced teachers.     

The engineer's role in the city

The European Society for Engineering Education is holding its eighth annual Conference in Paris this year. Our capital is greatly honoured to welcome for a few days the qualified representatives of a great number of European countries. This is the first SEFI meeting in France since your very first Conference in 1973. It is fortunate that this Conference is being held in Paris and that it has been possible to organize it with the close collaboration of the Engineering Schools (Grandes Ecoles) and the active help of the Study Committee for Engineering-training.     

Engagement versus participation: A difference that matters

The kind of engagement that transforms a person is more than mere participation. It is risk‐taking, spontaneous, socially supported, heart‐pounding co‐creation. Some campuses, the University of Maryland Baltimore County for one, are taking small steps to foster this kind of engagement. They've found that it's good, hard work.