The effect of different sports specialization on ankle joint mobility of young players

The aim of the study was to investigate the effects of practicing different sports on ankle joint mobility (AJM) in young subjects. In 344 players of 5 different sports (soccer, classical ballet, gymnastics, volleyball and basketball), mean age 12.0±2.4 years, sex (male/female: 237/107), BMI 19.0±2.8 (Kg/m 2 ), AJM was evaluated by using an inclinometer while the trunk flexibility was evaluated by the Sit and Reach test. Compared to all other groups, soccer players showed a significant reduction of AJM (p<.005) that is already present in younger subjects and that tends to worsen with aging (p<.04). On the contrary, the young dancers of classic ballet showed a significant increase in the AJM (p<.002). Basketball, volleyball and gymnastics groups showed a similar AJM. The higher AJM showed by females compared to males (128.5±21.0° vs 144.6±18.5°; p<.001) was not significant when the group of soccer players and dancers were excluded from the calculation. All groups investigated did not show a different mobility between the two ankles or the dominant and non-dominant limb. The age of the subjects investigated was not correlated with AJM. The group of gymnasts showed a significant increase in trunk flexibility (p<.001) compared to all other groups. Sport practice can significantly modify AJM both by increasing and reducing it. Such process should be timely assessed in order to prevent these alterations along with the related possible negative effects in the short and long term

Setting Cut-Scores for Complex Performance Assessments: A Critical Examination of the Analytic Judgment Method

The purpose of this article is to promote an increased awareness of the processes for setting cut-scores for complex performance assessments by (a) describing the Analytic Judgment Method (AJM) for setting cut-scores, and (b) critically evaluating the technical adequacy and practicability of the AJM by focusing on one investigation where the AJM was used by Plake and Hambleton (2001) for setting standards on the Pennsylvania Grade 8 Mathematics Achievement Test. Although Plake and Hambleton (1998, 2001) demonstrate that the AJM is an attractive iterative procedure that uses independent judgments of actual student work, more research is necessary to replicate the results and determine whether the AJM would produce high interrater reliability with more traditionally sized panels of 20 or more representatives.L’objectif de cet article est de conscientiser quant aux processus employés pour déterminer les seuils de passage dans les évaluations de tâches complexes. D’une part, nous décrivons la méthode basée sur le choix raisonné (Analytic Judgment Method, AJM) pour établir les seuils de passage et, d’autre part, nous évaluons la suffisance technique et la possibilité de mise en œuvre de la AJM en étudiant l’emploi qu’en ont fait Plake and Hambleton (2001) dans l’établissement de normes pour un test de rendement en mathématiques qu’on fait passer aux élèves en 8e année en Pennsylvanie. Bien que Plake and Hambleton (1998, 2000, 2001) ait démontré que la AJM constitue une procédure itérative prometteuse pour évaluer de façon indépendante les travaux des élèves, il faudrait entreprendre davantage de recherche pour répéter les résultats et déterminer si la AJM entraînerait un indice plus élevé de cohérence inter-juges chez un groupe d’experts de taille plus traditionnelle où il y irait au moins 20 membres représentatifs

Design and Analysis of Elliptical Nozzle in AJM Process using Computational Fluid Dynamics

Abrasive jet machining (AJM) is a micromachining process, where material is removed from the work piece by the erosion effect of a high speed stream of abrasive particles carried in a gas medium, which are emerging from a nozzle. Abrasive machining includes grinding super finishing honing, lapping polishing etc. The common nozzle shape presently used in AJM machining process is rectangle and circular shape nozzle which gives a low flow rate and further demands on decreasing the material removal rate (MRR), so this research mainly focuses on designing nozzle geometry to improve flow rate and MRR in AJM machining process. The elliptical shape nozzle has been designed and analyzed using computational fluid dynamics software (CFD). CFD is the most efficient software for flow rate analysis. The result shows the improvement in flow rate about 574.2m/sec and MRR of newly designed nozzle geometry i.e elliptical shape in abrasive jet machining

Lower limb posture and joint mobility in young Soccer players

none8noSoccer practice can induce marked changes in the lower limbs with dreaded short and long term consequences. We evaluated the possible effects of sport practice on lower limb posture and their relationships with ankle joint mobility (AJM). In 61 male Soccer players mean age 11.6±1.8 years, and in 50 Volleyball and Basketball players matched for age, sex and body mass index, lower limb posture and AJM in both plantar flexion and dorsiflexion were evaluated on the sagittal plane in supine position using, respectively, images analysis and an inclinometer. A multivariate analysis of variance was carried out to assess if the practice of different sports affects the leg posture (FP: angle between foot and leg) and foot posture (LP: angle between the foot and the line perpendicular to the ground). The sport practiced showed a significant multivariate effect on the lower limb posture. Soccer players showed a greater LP angle (169.2±4.3° vs 164.9±4.5°; p&lt;0.001) and a lesser FP angle in both Basketball and Volleyball players (298.0±12.6° vs 305.6±10.9°; p&lt;0.002). These differences were not present between the Basketball and Volleyball players. Soccer players showed a reduced AJM (127.6±15.7° vs. 138.8±21.6°; p&lt;0.002) compared to the other subjects evaluated. The AJM was found directly correlated to the FP angle (p&lt;0.005). The results of this study indicate that young Soccer players could show an altered posture of the leg and foot and a reduced AJM. The alterations of these parameters seem to be a consequence of the sport practice.openFrancia, Piergiorgio; Ferri Marini, Carlo; Toni, Sonia; Lucertini, Francesco; Federici, Ario; Iannone, Giulia; Paternostro, Ferdinando; Piccini, BarbaraFrancia, Piergiorgio; Ferri Marini, Carlo; Toni, Sonia; Lucertini, Francesco; Federici, Ario; Iannone, Giulia; Paternostro, Ferdinando; Piccini, Barbar

Progress in fluidized bed assisted abrasive jet machining (FB-AJM): Internal polishing of aluminium tubes

This paper deals with the internal finishing of tubular components made from a high strength aluminium alloy (AA 6082 T6) using a fluidized bed assisted abrasive jet machining (FB-AJM) system. Firstly, a Taguchi's experimental plan was used to investigate the influence of abrasive jet speed, machining cycle, and abrasive mesh size on surface roughness and material removal trends. Secondly, the leading finishing mechanisms were studied using combined 3d profilometer-SEM analysis to monitor the evolution of the surface morphology of machined workpieces. Finally, the circumferential uniformity and precision machining of the inner surface of workpieces were tested by evaluating the values of the more significant roughness parameters in different circumferential locations. Consistent trends of surface roughness vs. operational parameters were measured, and significant material removal was found to affect the workpieces during machining. As a result, FB-AJM was found to preferentially machine the asperities and irregularities of the surface, thereby altering the overall surface morphology producing more regular and smoother finishing. Moreover, the good circumferential uniformity and machining accuracy FB-AJM guarantees even on ductile aluminium alloy workpieces ensure that this technology can be applied to a diverse set of industrial components. (C) 2006 Elsevier Ltd. All rights reserved