349 research outputs found
Optimal trajectory tracking control for a wheeled mobile robot using backstepping technique
This work studies an optimal trajectory tracking of a wheeled mobile robot with the objective of minimizing energy consumption. First, the mathematical model, which takes into account the kinematic model of the mobile robot and the dynamic model of the actuators is presented. Then, a backstepping controller is designed and its parameters are tuned to satisfy several strict criteria such as rapid convergence, matching desired trajectory, and minimizing energy. For that, two cost functions were investigated and the best one has been selected. The significant reduction in energy losses achieved for all the proposed motion scenarios proves the effectiveness of our approach
Haemophilus paraphrophilus brain abscess in a 9-year-old boy: Case report and literature review
Human diseases due to A. paraphrophilus arenât usual. The following case report describes the first isolated case of A. paraphrophilus brain abscess in our laboratory. A 9-year-old boy presented to pediatric emergencies for frontal headache, vomiting, blurred vision and left hemiparesis. Radiological diagnosis consists with a frontal abscess. Gram staining of purulent samples showed abundant neutrophils with gram negative bacilli. Culture was made on blood agar, chocolate agar, Chapmanâs agar and incubated in 5% CO2 at 37°C for 24 hours. Positive culture was detected only on chocolate agar. It was monomicrobial with small yellowish non-hemolytic colonies. Gram stain of colonies showed pleomorphic gram-negative coccobacilli. The strain required V factor for growth. The isolated strain was sensitive to all antibiotics tested. The interest of this case is that it shows the emergence of A. paraphrophilus as a causative agent of brain abscesses on pediatric population without associated congenital heart disease. It may also help identifying risk factors of these infections and how to prevent them
LâĂ©cole quĂ©bĂ©coise assure-t-elle lâĂ©galitĂ© des chances ? Le cheminement scolaire des jeunes noirs au secondaire
Cet article prĂ©sente les rĂ©sultats du suivi de trois cohortes (1994, 1995, 1996) dâĂ©lĂšves francophones, anglophones et crĂ©olophones, nĂ©s dans les Antilles ou en Afrique ou dont au moins un des deux parents est nĂ© dans ces rĂ©gions, de leur entrĂ©e Ă lâĂ©cole secondaire quĂ©bĂ©coise de langue française jusquâĂ lâobtention de leur diplĂŽme au cĂ©gep. Ces Ă©lĂšves ont Ă©tĂ© comparĂ©s, dâune part avec lâensemble des Ă©lĂšves et, dâautre part, avec lâensemble des Ă©lĂšves issus de lâimmigration (premiĂšre et deuxiĂšme gĂ©nĂ©rations). Dans la premiĂšre partie, les auteurs donnent un aperçu des caractĂ©ristiques sociales et Ă©ducatives des cinq sous-groupes. Leur expĂ©rience scolaire est ensuite dĂ©crite Ă lâaide des divers indicateurs disponibles dans les banques de donnĂ©es administratives du ministĂšre de lâĂducation (Ăąge Ă lâarrivĂ©e au secondaire; retard scolaire en secondaire 3; identification comme Ă©lĂšve Ă besoins particuliers; taux dâobtention dâun diplĂŽme aprĂšs 5, 6 ou 7 ans de scolaritĂ© secondaire; accĂšs au cĂ©gep et taux dâobtention dâun diplĂŽme collĂ©gial. Finalement, les auteurs explorent lâimpact dâun ensemble de variables socio-dĂ©mographiques et scolaires sur les taux dâobtention dâun diplĂŽme secondaire.This article presents the results of a systematic tracking of 3 cohorts (1994, 1995, 1996) of Francophone, Anglophone and Creolophone students, born in the West Indies or Africa, or who have at least one parent born in these regions, from their entrance in the secondary French language school system of Quebec through their diplomation at the end of junior college. These students are compared with the entire school population and the sub-group of first and second generation immigrant students. In the first part, the authors give an overview of the social and educational characteristics of the 5 sub-groups. They then describe their schooling experience using various indicators available in the Department of Educationâs administrative data banks, such as age when entering junior high school and when reaching senior high school; identification as « at risk » student; rate of high school diplomation after five, six or seven years; access to junior college and rate of diplomation at that level. Finally, they explore the impact of various sociodemographic and school-related variables on the rate of high school diplomation
PERCEPTION ET REPRESENTATION DU MOUVEMENT : INFLUENCES DE LA VERBALISATION SUR LA RECONNAISSANCE DE MOUVEMENTS DâESCRIME EN FONCTION DE LâEXPERTISE
Abstract- Is it necessary to verbalize in order to memorize and learn a material? According to the literature examining the influence of verbalizations on learning and memory, the answer to this question depends on the type of material used (conceptual material versus perceptive material) and on the learnersâ level of expertise. In Study 1, we examined the influence of verbal descriptions on the visual recognition of sequences of fencing movements, with participants of the three levels of expertise (novices, intermediates, experts). In Study 2, we studied the influence of different content of verbal descriptions on the recognition of sequences of fencing movements, according to the level of expertise. The goal of Study 3 was to examine the effect on memory of a trace distinct from a verbal trace: a motor trace. The findings of Study 1 show that verbalizing improves novicesâ recognition, impairs intermediatesâ recognition and has no effect on expertsâ recognition. The results of Study 2 show that the content of verbal descriptions has an effect on memory, according to the participantsâ level of expertise. The findings of Study 3 show that duplicating the fencing movement, with no feedback, strongly impedes beginnersâ visual recognition. These findings broaden the verbal overshadowing phenomena to a material distinctly more conceptual than the one classically used in this field of research. They bring strong support to the theoretical hypothesis of interference resulting from a verbal recoding (Schooler, 1990). They also show that an additional motor trace can harm visual recognition of movement sequences.Faut-il verbaliser pour mĂ©moriser et apprendre ? DâaprĂšs la littĂ©rature examinant lâinfluence des verbalisations sur lâapprentissage et la mĂ©moire, la rĂ©ponse Ă cette question dĂ©pend du type de matĂ©riel utilisĂ© (matĂ©riel conceptuel versus matĂ©riel perceptif) et du niveau dâexpertise des apprenants. Dans lâĂtude 1, nous avons examinĂ© lâincidence de descriptions verbales sur la reconnaissance visuelle de sĂ©quences de mouvements dâescrime, avec des participants de trois niveaux dâexpertise (novices, intermĂ©diaires et experts). Dans lâĂtude 2, nous avons Ă©tudiĂ© lâinfluence de diffĂ©rents contenus de descriptions verbales sur la reconnaissance de sĂ©quences de mouvements dâescrime, en fonction de lâexpertise. Lâobjectif de lâĂtude 3 Ă©tait dâexaminer lâeffet sur la mĂ©moire dâune trace autre que verbale : une trace motrice. Les rĂ©sultats de lâĂtude 1 montrent que verbaliser amĂ©liore la reconnaissance des novices, altĂšre celle des intermĂ©diaires et nâa aucun effet sur la reconnaissance des experts. Les rĂ©sultats de lâĂtude 2 montrent que le contenu des descriptions verbales a une incidence sur la mĂ©moire, en fonction du niveau dâexpertise des participants. Les rĂ©sultats de lâĂ©tude 3 montrent que reproduire le mouvement dâescrime, sans feedback, nuit Ă la reconnaissance visuelle des participants novices. Ces rĂ©sultats Ă©largissent le phĂ©nomĂšne dâombrage verbal Ă un matĂ©riel nettement plus conceptuel que celui qui est classiquement utilisĂ© dans ce domaine de recherche. Ils apportent un Ă©tayage solide Ă la proposition thĂ©orique de lâinterfĂ©rence rĂ©sultant dâun recodage verbal (Schooler, 1990). Ils montrent Ă©galement quâune trace motrice additionnelle peut nuire Ă la reconnaissance visuelle de sĂ©quences de mouvements
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