Le Volume comme Instrument de Conceptualisation de l'Espace

Peer Reviewe

Le rapport caractérisation-validation dans une activité d’exploration en géométrie

Cet article présente la synthèse d'une étude sur les difficultés des élèves du secondaire à produire des démonstrations en géométrie. Il aborde ce problème dans un cadre d'exploration et à partir d'une analyse du rapport liant le raffinement de la caractérisation des objets mathématiques au développement de la validation mathématique. Le traitement expérimental proposé pour résoudre ce problème illustre le rôle que joue la manipulation dans le raffinement de la caractérisation des objets et dans le développement de la validation mathématique.This article presents the results of a study of secondary level students' difficulties in producing geometry demonstrations. This problem is examined within an exploratory frame and is based on an analysis of links between the characterization of mathematical objects and the development of mathematical validation. The experimental treatment proposed illustrates the role of manipulation in representing objects and in developing mathematical validation.Este articulo présenta la sfntesis de un estudio de dificultades de alumnos de secundaria en la realizacion de demostraciones geométricas. Se aborda el problema dentro de un marco de exploracion partiendo de un analisis de la relacion entre el refinamiento de la caracterizacion de objetos matemàticos y el desarrollo de una validaciôn matemàtica. El tratamiento experimental ilustra el papel que juega la manipulacion dentro del refinamiento de la caracterizacion de objetos y dentro del desarrollo de la validaciôn matemàtica.Im vorliegenden Artikel wird zusammenfassend eine Studie dar- gestellt iiber die Unfâhigkeit der Schiller der Mittelschule, geometrische Beweisfiïhrungen anzustellen. Dieses Problem wurde innerhalb von Experimentierperioden untersucht, wobei ausgegangen wird von einer Analyse des Verhâltnisses zwischen der Verfeinerung der Vorstellung, die der Schiller von mathematischen Objekten hat, und der Entwicklung der mathematischen Bestàtigung. Das experimentelle Verfahren, das hier zur Lôsung dieses Problems vorgeschlagen wird, bezeugt die Rolle, die die konkrete Handhabung bei der Verfeinerung der Objektvorstellungen und bei der Entwicklung der mathematischen Bestàtigung spielt

Réponses de Claude Simon à quelques questions écrites de Ludovic Janvier

Ludovic Janvier : – Vous avez écrit douze livres. Longue affaire. Quel rapport avez-vous avec ce discours entretenu depuis trente ans, et qui paraît au-dehors sous le nom de Claude Simon ? Claude Simon : – Longue affaire, comme vous dites. Et naturellement, en trente ans le rapport s’est quelque peu modifié. Mais il faudrait plutôt parler de rapports, au pluriel, car il y a, d’une part, ceux qu’entretient un écrivain avec son œuvre faite, de l’autre, ceux qu’il entretient avec l’œuvre qu’il e..

Challenges for optical turbulence characterization and prediction at optical communication sites

editorial reviewedModelling of atmospheric optical turbulence has been of interest in astronomy for several decades, e.g. for site characterization and flexible scheduling. Nowadays, it is also considered for free-space optical communications, namely to conduct site selection and to design future optical communication systems. In this work, a general approach relying on numerical weather prediction simulations in order to perform optical turbulence prediction is presented. The approach makes use of the Weather Research and Forecasting model and raises several challenges. The latter, such as the choice of the C_n^2 models or the required temporal and spatial resolutions, are first discussed with regards to the literature. Then, optical turbulence prediction is conducted for the site of Redu, Belgium, illustrating the different challenges. These predictions are also compared with seeing measurements from a differential image motion monitor. The presented approach offers realistic seeing values that, however, do not follow rapid variations of the measured seeing. Origins of the discrepancies between measurements and predictions are to be found in the modelling of the boundary layer and motivate the use of a C_n^2 model relying on the turbulent kinetic energy. Further simulations and measurement campaigns at other optical communication sites are encouraged in order to refine some model parameters and compare statistically the prediction results.SALT

The global abundance of tree palms

Aim Palms are an iconic, diverse and often abundant component of tropical ecosystems that provide many ecosystem services. Being monocots, tree palms are evolutionarily, morphologically and physiologically distinct from other trees, and these differences have important consequences for ecosystem services (e.g., carbon sequestration and storage) and in terms of responses to climate change. We quantified global patterns of tree palm relative abundance to help improve understanding of tropical forests and reduce uncertainty about these ecosystems under climate change. Location Tropical and subtropical moist forests. Time period Current. Major taxa studied Palms (Arecaceae). Methods We assembled a pantropical dataset of 2,548 forest plots (covering 1,191 ha) and quantified tree palm (i.e., ≥10 cm diameter at breast height) abundance relative to co‐occurring non‐palm trees. We compared the relative abundance of tree palms across biogeographical realms and tested for associations with palaeoclimate stability, current climate, edaphic conditions and metrics of forest structure. Results On average, the relative abundance of tree palms was more than five times larger between Neotropical locations and other biogeographical realms. Tree palms were absent in most locations outside the Neotropics but present in >80% of Neotropical locations. The relative abundance of tree palms was more strongly associated with local conditions (e.g., higher mean annual precipitation, lower soil fertility, shallower water table and lower plot mean wood density) than metrics of long‐term climate stability. Life‐form diversity also influenced the patterns; palm assemblages outside the Neotropics comprise many non‐tree (e.g., climbing) palms. Finally, we show that tree palms can influence estimates of above‐ground biomass, but the magnitude and direction of the effect require additional work. Conclusions Tree palms are not only quintessentially tropical, but they are also overwhelmingly Neotropical. Future work to understand the contributions of tree palms to biomass estimates and carbon cycling will be particularly crucial in Neotropical forests

Tropical Data: Approach and Methodology as Applied to Trachoma Prevalence Surveys

PURPOSE: Population-based prevalence surveys are essential for decision-making on interventions to achieve trachoma elimination as a public health problem. This paper outlines the methodologies of Tropical Data, which supports work to undertake those surveys. METHODS: Tropical Data is a consortium of partners that supports health ministries worldwide to conduct globally standardised prevalence surveys that conform to World Health Organization recommendations. Founding principles are health ministry ownership, partnership and collaboration, and quality assurance and quality control at every step of the survey process. Support covers survey planning, survey design, training, electronic data collection and fieldwork, and data management, analysis and dissemination. Methods are adapted to meet local context and needs. Customisations, operational research and integration of other diseases into routine trachoma surveys have also been supported. RESULTS: Between 29th February 2016 and 24th April 2023, 3373 trachoma surveys across 50 countries have been supported, resulting in 10,818,502 people being examined for trachoma. CONCLUSION: This health ministry-led, standardised approach, with support from the start to the end of the survey process, has helped all trachoma elimination stakeholders to know where interventions are needed, where interventions can be stopped, and when elimination as a public health problem has been achieved. Flexibility to meet specific country contexts, adaptation to changes in global guidance and adjustments in response to user feedback have facilitated innovation in evidence-based methodologies, and supported health ministries to strive for global disease control targets

Didacticiel, programmation et interdisciplinarité

In the first part, we describe an experimental computer program that serves as a framework for the questions raised later in this article. This educational program is put in relation to a particular learning theory and illustrates the importance of undertaking an epistemological analysis of the concepts to be developed. A second short section discusses how this computer program might be used in a school context. The third part is largely devoted to issues related to the use of computing languages to meet pedagogical ends. We conclude this part by raising selected problems to which only an interdisciplinary approach can bring solutions. A brief final section revisits the analysis of the various disciplinary contributions that could be made to enhance the quality of a learning computer program in the perspective of authoring languages.Nous présentons dans une première partie un didacticiel expérimental qui sert de toile de fond aux diverses questions soulevées dans l'article. Le didacticiel est situé par rapport à une théorie de l'apprentissage et illustre le besoin d'une analyse épistêmologique des objets d'apprentissage. Une deuxième partie, brève, examine l'accueil que réserve l'Ecole à ce type de didacticiel. Nous examinons dans la troisième partie quelques questions liées à l'utilisation des langages de programmations à des fins didactiques. Nous concluons cette partie en soulevant quelques problèmes auxquels seule une démarche interdisciplinaire peut apporter des solutions. Une courte quatrième section reprend le thème du bon didacticiel tout en le situant par rapport aux langages d'auteur.Janvier Claude. Didacticiel, programmation et interdisciplinarité. In: Enfance, tome 38, n°2-3, 1985. L'ordinateur et l'écolier (II) : recherches expérimentales. pp. 117-132

Contextualisation et représentation en mathématiques /

Août 1990Bibliogr.: f. 2