456 research outputs found
The Effectiveness of Hooks for Plain Steel Reinforcement
As buildings age, their structural integrity must be assessed and reassessed at regular intervals to ensure the safety of their continued use and to advise on retrofits and repairs necessary for preventative maintenance and responsive repair. Historic buildings often contain plain reinforcement whereas modern buildings exclusively contain modern deformed reinforcement. Younger engineers in particular have not been trained with or worked with plain bar. Modern American Concrete Institute (ACI) and Canadian Standards Association (CSA) Group codes largely do not contain adequate provisions to assess the structural integrity of many historic buildings.
Twenty-four beam-column joint specimens with four different hook configurations were tested under tension to compare the anchorage capacities of embedded plain and modern deformed 90° and 180° hooked bars. Six replicates of each configuration were tested to determine whether statistically significant differences at the 95% confidence level existed between the anchorage capacities of plain versus modern deformed hooked bars. Visual observations were documented manually to assess differences between crack patterns and observed failure modes.
Typical cracking patterns were observed for groups of both specimens containing 90° and 180° hooks. The degree of cracking observed aligned with results of similar studies. All specimens with 90° hooks failed by side blowout whereas those with 180° hooks failed by front blowout. No evidence of group effects (i.e. decreased anchorage capacity) was observed. Statistically significant differences in maximum normalized tensile load at the 95% confidence level were observed between 90° plain and modern deformed bars, wherein the plain bars had a 3.8 kN/MPa lower maximum; 180° plain and modern deformed bars, wherein the plain bars had a 5.6 kN/MPa lower maximum; and 90° and 180° modern deformed hooked bars, wherein the 90° bars had a 4.0 kN/MPa lower maximum. No statistically significant differences in displacement at maximum normalized load were observed.
An extensive replicate-based study of plain hooked bar incorporating additional parameters (e.g. lead length, bend angle, etc.) is recommended. The value of the recommended work is in determining the sensitivity of hooked bar performance to variations in these parameters
Enseigner les techniques sportives dans une classe d'Ăducation physique en RĂ©seau ambition rĂ©ussite : une activitĂ© " situĂ©e ", Ă©mergente et socialement construite
International audienceThis study in "situated action" analyzes the activity of the pupils, the teacher and the way they are linked in the context of difficult classes in RAR (RĂ©seau Ambition RĂ©ussite). It aims at understanding what "appears in act" during physical education lessons in this specific context of RAR and in particular what can explain the difficulties the teacher can have in transmitting sports techniques.Cette Ă©tude en anthropologie cognitive situĂ©e analyse l'activitĂ© des Ă©lĂšves, de l'enseignant et leur articulation dans le cadre de classes difficiles en RAR (RĂ©seau ambition rĂ©ussite). Elle vise Ă comprendre ce qui " fait l'actualitĂ© " de l'Ăducation Physique et Sportive (EPS) dans le contexte particulier des RAR et notamment ce qui peut expliquer les difficultĂ©s de l'enseignant Ă transmettre des techniques corporelles et sportives
Mettre une classe au travail en Réseau Ambition Réussite : des formes typiques d'interaction enseignant-élÚves lors de leçons d'EPS
International audienceThis study carried out in an "Ambition Réussite" secondary school, aims at understanding how experienced physical education teachers manage in a lasting way, to set a class to work, during a lesson, with pupils who are not prone to engage in a study activity. It analyses: a) the teacher's actions in order to construct a collective activity of viable work, b) of the significances which he allots to the pupils' engagement in work during the lesson, c) in order to identify the typical forms of interaction teacher-pupils which underlie this collective activity of work. It is led on the anthropology framework, under the ideal and methodological model of the "Course of action" (Theureau, 1992/2004). It rests on ethnographic materials and verbalizations during post-protocol interviews. The results reveal the existence of typical forms of interaction in the class, relating to: a) the interactions' management of space b) focusing on prescriptive work, c) a tolerance to ludic transgressions d) a perception of the limit threshold of deviance.Cette étude effectuée dans un collÚge " Ambition réussite " vise à comprendre comment des enseignants d'EPS expérimentés parviennent de façon durable à mettre une classe au travail au cours d'une leçon avec des élÚves peu enclins à s'engager dans une activité d'étude. Elle vise à rendre compte : a) des actions de l'enseignant pour construire une activité collective de travail viable, b) des significations qu'il attribue à l'engagement des élÚves dans le travail au cours de leçon, c) des formes typiques d'interaction enseignant-élÚves qui sous-tendent cette activité collective de travail. Elle est conduite dans le cadre de l'anthropologie, sous le modÚle théorique et méthodologique du " Cours d'action " (Theureau, 1992/2004). Elle s'appuie sur des matériaux ethnographiques et des verbatim d'entretiens d'autoconfrontation. Les résultats révÚlent l'existence de formes typiques d'interaction dans la classe, relatives : a) à la gestion spatiale des interactions, b) à la focalisation sur le travail à effectuer, c) à une tolérance aux transgressions ludiques, d) à une perception de seuils-limites de déviance
MOEMS deformable mirror testing in cryo for future optical instrumentation
MOEMS Deformable Mirrors (DM) are key components for next generation
instruments with innovative adaptive optics systems, in existing telescopes and
in the future ELTs. These DMs must perform at room temperature as well as in
cryogenic and vacuum environment. Ideally, the MOEMS-DMs must be designed to
operate in such environment. We present some major rules for designing /
operating DMs in cryo and vacuum. We chose to use interferometry for the full
characterization of these devices, including surface quality measurement in
static and dynamical modes, at ambient and in vacuum/cryo. Thanks to our
previous set-up developments, we placed a compact cryo-vacuum chamber designed
for reaching 10-6 mbar and 160K, in front of our custom Michelson
interferometer, able to measure performances of the DM at actuator/segment
level as well as whole mirror level, with a lateral resolution of 2{\mu}m and a
sub-nanometric z-resolution. Using this interferometric bench, we tested the
Iris AO PTT111 DM: this unique and robust design uses an array of single
crystalline silicon hexagonal mirrors with a pitch of 606{\mu}m, able to move
in tip, tilt and piston with strokes from 5 to 7{\mu}m, and tilt angle in the
range of +/-5mrad. They exhibit typically an open-loop flat surface figure as
good as <20nm rms. A specific mount including electronic and opto-mechanical
interfaces has been designed for fitting in the test chamber. Segment
deformation, mirror shaping, open-loop operation are tested at room and cryo
temperature and results are compared. The device could be operated successfully
at 160K. An additional, mainly focus-like, 500 nm deformation is measured at
160K; we were able to recover the best flat in cryo by correcting the focus and
local tip-tilts on some segments. Tests on DM with different mirror thicknesses
(25{\mu}m and 50{\mu}m) and different coatings (silver and gold) are currently
under way.Comment: 11 pages, 12 Figure
A New Record Size Wolf, Canis lupus, Group for Ontario
This report documents a group of 19 Wolves (Canis lupus) in northwestern Ontario. This is the largest group observed since record keeping in the Moose Aerial Inventory commenced in 1995. This large group may be a response to a high Moose (Alces alces) population in the Red Lake area
Complex links between dietary lipids, endogenous endotoxins and metabolic inflammation.
International audienceMetabolic diseases such as obesity are characterized by a subclinical inflammatory state that contributes to the development of insulin resistance and atherosclerosis. Recent reports also indicate that (i) there are alterations of the intestinal microbiota in metabolic diseases and (ii) absorption of endogenous endotoxins (namely lipopolysaccharides, LPS) can occur, particularly during the digestion of lipids. The aim of the present review is to highlight recently gained knowledge regarding the links between high fat diets, lipid digestion, intestinal microbiota and metabolic endotoxemia & inflammation
La dynamique du dĂ©crochage local des Ă©lĂšves en classe structurĂ©e par un faisceau de prĂ©occupations « travail â jeu »
Cette recherche considĂšre le dĂ©crochage comme un processus, issu dâun parcours personnel et ayant sa propre dynamique trouvant ses origines Ă lâintĂ©rieur de la classe par des comportements non conformes au travail scolaire. Lâobjet de notre Ă©tude est de comprendre la dynamique du dĂ©crochage local, situĂ©, en analysant lâactivitĂ© des Ă©lĂšves en cours dâĂ©ducation physique et sportive (EPS) dans des Ă©tablissements appartenant Ă la politique dâĂ©ducation prioritaire. Le cadre thĂ©orique et mĂ©thodologique mobilisĂ© est celui du âcours dâactionâ (Theureau, 2006). Le dĂ©crochage local du travail scolaire est analysĂ© au regard de lâengagement des Ă©lĂšves dans la leçon en fonction de leurs bifurcations de prĂ©occupations. Onze Ă©lĂšves de 6Ăšme et 5Ăšme ont participĂ© Ă cette Ă©tude dans un dispositif de gymnastique par ateliers. Le recueil de matĂ©riaux sâest fait Ă partir dâenregistrements audiovisuels et dâentretiens dâautoconfrontation. Leur traitement a visĂ© Ă rendre compte de lâactivitĂ© des Ă©lĂšves et en particulier leurs prĂ©occupations, perceptions et connaissances mobilisĂ©es dans lâaction. Les rĂ©sultats montrent que lâactivitĂ© des Ă©lĂšves est organisĂ©e par un faisceau de prĂ©occupations « travail â jeu » comprenant une dynamique propre alternant des phases de dĂ©crochage et de raccrochage au travail scolaire.This research considers the dropout as a process, from a personal course and having its own dynamics finding its origins within the classroom by misbehavior. The purpose of our study is to understand the dynamics of local drop-out by analyzing the activity of students during physical education class in middle schools belonging to the compensatory policy. The theoretical and methodological framework used is the âcourse of actionâ (Theureau, 2006). The local dropout of school work is analyzed in terms of student engagement in the lesson according to their concerns bifurcations. Eleven students from 6th and 5th in middle schools were studied in a gymnastics workshops. The collection of data is made from video recordings and interviews of self-confrontation. Data processing aimed to analyze the activity of the students and in particular their concerns, perceptions and knowledge used in action. The results show that the activity of the students is organized by two concerns âwork - playâ including its own dynamic alternating phases of drop-out and of hang up the school work
Ăditorial
Ce troisiĂšme numĂ©ro spĂ©cial de la revue eJRIEPS est consacrĂ© aux actes de la 11Ăšme Biennale de lâAssociation pour la recherche sur lâintervention en sport qui sâest tenue Ă Lille du 19-21 juin 2018. Le colloque intitulĂ© « L'intervention dans les pratiques physiques, sportives et artistiques : ResponsabilitĂ©s et StratĂ©gies des acteurs » sâest centrĂ© sur lâanalyse de lâintervention en sport et en Ă©ducation physique. Les activitĂ©s physiques, sportives, et artistiques apparaissent souvent comme u..
How can video feedback be used in physical education to support novice learning in gymnastics? Effects on motor learning, self-assessment and motivation
Background:
Much of the existing research concerning the use of video
feedback (VFB) to enhance motor learning has been undertaken under
strictly controlled experimental conditions. Few studies have sought to
explore the impact of VFB on the skill learning experience of the students
in a structured, school-based physical education (PE) setting. Most of those
studies have only used qualitative approaches to implicate the potential
value of VFB to enhance skill acquisition, students
â
engagement or self-
assessment ability. Using a quantitative approach, the aim of this study
was to investigate effects of using VFB on motor skill acquisition, self-
assessment ability and motivation in a school-based learning environment
(structured PE programme) with novice children learning a gymnastic skill.
Method:
Two French classes of beginners took part in a typical
five-week
learning programme in gymnastics. During each of the
five, weekly
lessons participants carried out the same warm-up routine and exercises.
The experimental group (10 girls
â
8 boys, 12.4 ± 0.5 years) received VFB
intermittently when learning a front handstand to
flat back landing. VFB
was given after every
five attempts, combined with self-assessment and
verbal instructions from the teacher. The control group (12 girls
â
13 boys,
12.6 ± 0.4 years) received exactly the same training but was not given VFB.
In order to assess progress in motor skills, the arm-trunk angle (hand-
shoulder-hip) was measured in the sagittal plane just as the hips formed a
vertical line with the shoulders. Motivation was assessed using the
Situational Motivation Scale questionnaire (Guay, F., R. J. Vallerand, and
C. Blanchard. 2000.
â
On the Assessment of Situational Intrinsic and
Extrinsic Motivation: The Situational Motivation Scale (SIMS).
â
Motivation
and Emotion
24 (3): 175
â
213), and self-assessment ability was measured
by self-perception task scores.
Results:
Statistical analysis of arm-trunk angle values showed significant differences only for the VFB group between the
fifth lesson and all other lessons. Between lessons 4 and 5, the arm-trunk angle value increased
significantly from 146.6 ± 16.9 degrees to 161.2 ± 14.2 degrees (
p
< .001;
ES = 0.94). Self-assessment scores improved significantly for the VFB group
between lesson 1 and lesson 2 (
p
< 0.01, ES = 1.79) and between lesson 4
to lesson 5 (
p
< .01, ES = 0.94). Amotivation decreased significantly for
the VFB group between lesson 1 and lesson 5 (3.06 ± 1.42 vs. 2.12 ± 0.62,
p
< .001, ES =
â
0.89).
Discussion/conclusion:
Our quantitative data, identifying key movement
changes as a function of experience in a structured PE programme, were
congruent with outcomes of previous qualitative research supporting the
role of VFB. This study highlights the potential relevance of using VFB in
fostering motor learning, motivation and self-assessment during a PE
programme with young children. Future pedagogical research is needed
to examine the ways students could use VFB technology for greater self-
regulation, with the potential to deliver appropriate movement feedback,
based on different levels of experience in students
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