Des récréations pour enseigner les mathématiques avec Lucas, Fourrey, Laisant

International audienceSourceURL:file://localhost/Users/evelynebarbin/Desktop/Article-HPM%202016-Actes/HPM2016-+Barbin&Guitart.doc À la fin du xixe siècle, il existe un retour aux récréations mathématiques dans une communauté française de mathématiciens, enseignants et amateurs. La nouveauté de ce retour est la volonté des auteurs d'inscrire les récréations dans l'histoire des mathématiques, de rechercher leur valeur pour l'enseignement et de développer de nouvelles mathématiques pour résoudre les problèmes qui leur sont liés. Nous trouvons ces trois intérêts historiques, pédagogiques et mathématiques chez Édouard Lucas, Émile Fourrey et Charles-Ange Laisant. Les récréations choisies par eux indiquent un continuum entre les trois propos. Avec eux, les récréations ne sont pas seulement un moyen d'amuser et elles deviennent une matière sérieuse à enseigner, selon des conceptions mathématiques et éducatives que nous analysons dans cet article.</p

Les coordonnées curvilignes de Gabriel Lamé – Représentation des situations physiques et nouveaux objets mathématiques

Le mathématicien Viatcheslav V. Meleshko écrivait en 2003 à propos de Lamé : Les mathématiciens français, cependant, le considèrent comme trop pratique, et les ingénieurs français le considèrent comme trop théorique. Cela fait bien écho à l’idée maîtresse que Lamé exprimait lui-même ainsi : Ecartez à tout jamais la division de la science en mathématiques pures et en mathématiques appliquées. ce qui se résume brièvement et simplement dans l’expression : « physique mathématique ». C’est dans ce..

Chapitre 4. Une collaboration de Charles-Ange Laisant. L’algèbre et l’arithmétique graphiques de Gabriel Arnoux

Gabriel Arnoux a connu Charles-Ange Laisant au congrès de 1891 de l’Association française pour l’avancement des sciences (AFAS) à Marseille. Il semble que ce soit lui, qui soit allé au-devant du mathématicien et que celui-ci lui ait accordé aussitôt de l’intérêt. Leurs rencontres se poursuivront dans le réseau de l’AFAS, où échangent mathématiciens, enseignants et passionnés de mathématiques. Laisant devient l’interlocuteur privilégié d’Arnoux et leurs interactions s’inscrivent jusque dans l..

Dynamic simulation of the THAI heavy oil recovery process

Toe-to-Heel Air Injection (THAI) is a variant of conventional In-Situ Combustion (ISC) that uses a horizontal production well to recover mobilised partially upgraded heavy oil. It has a number of advantages over other heavy oil recovery techniques such as high recovery potential. However, existing models are unable to predict the effect of the most important operational parameters, such as fuel availability and produced oxygen concentration, which will give rise to unsafe designs. Therefore, we have developed a new model that accurately predicts dynamic conditions in the reservoir and also is easily scalable to investigate different field scenarios. The model used a three component direct conversion cracking kinetics scheme, which does not depend on the stoichiometry of the products and, thus, reduces the extent of uncertainty in the simulation results as the number of unknowns is reduced. The oil production rate and cumulative oil produced were well predicted, with the latter deviating from the experimental value by only 4%. The improved ability of the model to emulate real process dynamics meant it also accurately predicted when the oxygen was first produced, thereby enabling a more accurate assessment to be made of when it would be safe to shut-in the process, prior to oxygen breakthrough occurring. The increasing trend in produced oxygen concentration following a step change in the injected oxygen rate by 33 % was closely replicated by the model. The new simulations have now elucidated the mechanism of oxygen production during the later stages of the experiment. The model has allowed limits to be placed on the air injection rates that ensure stability of operation. Unlike previous models, the new simulations have provided better quantitative prediction of fuel laydown, which is a key phenomenon that determines whether, or not, successful operation of the THAI process can be achieved. The new model has also shown that, for completely stable operation, the combustion zone must be restricted to the upper portion of the sand pack, which can be achieved by using higher producer back pressure

Global patterns of care in advanced stage mycosis fungoides/Sezary syndrome: a multicenter retrospective follow-up study from the Cutaneous Lymphoma International Consortium

ABSTRACT Background Advanced-stage mycosis fungoides (MF)/Sezary syndrome (SS) patients are weighted by an unfavorable prognosis and share an unmet clinical need of effective treatments. International guidelines are available detailing treatment options for the different stages but without recommending treatments in any particular order due to lack of comparative trials. The aims of this second CLIC study were to retrospectively analyze the pattern of care worldwide for advanced-stage MF/SS patients, the distribution of treatments according to geographical areas (USA versus non-USA), and whether the heterogeneity of approaches has potential impact on survival. Patients and methods This study included 853 patients from 21 specialist centers (14 European, 4 USA, 1 each Australian, Brazilian, and Japanese). Results Heterogeneity of treatment approaches was found, with up to 24 different modalities or combinations used as first-line and 36% of patients receiving four or more treatments. Stage IIB disease was most frequently treated by total-skin-electron-beam radiotherapy, bexarotene and gemcitabine; erythrodermic and SS patients by extracorporeal photochemotherapy, and stage IVA2 by polychemotherapy. Significant differences were found between USA and non-USA centers, with bexarotene, photopheresis and histone deacetylase inhibitors most frequently prescribed for first-line treatment in USA while phototherapy, interferon, chlorambucil and gemcitabine in non-USA centers. These differences did not significantly impact on survival. However, when considering death and therapy change as competing risk events and the impact of first treatment line on both events, both monochemotherapy (SHR = 2.07) and polychemotherapy (SHR = 1.69) showed elevated relative risks. Conclusion This large multicenter retrospective study shows that there exist a large treatment heterogeneity in advanced MF/SS and differences between USA and non-USA centers but these were not related to survival, while our data reveal that chemotherapy as first treatment is associated with a higher risk of death and/or change of therapy and thus other therapeutic options should be preferable as first treatment approach

Dispositivos lingüísticos de acogida, aprendizaje expansivo e interculturalidad: Contribuciones para la inclusión educativa de estudiantes extranjeros

Indexación: Scopus.In the context of the progressive increase of foreigners in public schools in Chile and the recent changes in migratory patterns, the presence of students who do not master the working language of the educational system has systematically incremented in recent years. In a scenario marked by the absence of educational policies that respond to this new linguistic diversity, the purpose of our research was to understand how schools have responded to the arrival of foreign students and what educational practices they have implemented to tackle this challenge. Through a two-year school ethnography in four public schools with high enrollment of foreigners, institutional documents were analyzed and field observation, interviews and focus groups were conducted with different actors amidst the educational communities. Through an analysis of thematic content, the results reveal the implementation of ten devices to manage educational responses to foreign students. We have analyzed three of these devices with a focus on linguistics based on the tensions and contradictions that occur within the educational institutions of which they are part, identifying significant elements and dimensions to drive forward expansive learning. Finally, we discuss these findings in light of the advances and challenges of the intercultural approach in our Latin American region.https://www.scielo.br/j/ep/a/NhL67jbv7H7VpZtQYjtHVFt/?lang=e

Figures, lettres et preuves : pulsation et figurations au lieu de l’écriture

D’abord, comme exemple précis de mutation d’écriture nous proposons l’écriture de la notion d’objet borroméen. Toutefois le but de ce texte est plus large ; il s’agit de la prise en charge du fait même que les écritures mathématiques vivantes mutent, en posant à la racine de nos pratiques ceci : écrire fonde les écritures en étant l’objet même à écrire. Il s’agit d’écrire le fait d’écriture. Tout commence donc par ceci qu’il y a des figures projetées réalisées en traces sur des supports, et p..