Un peu d'épistémologie élémentaire, un clin d'oeil à Ferdinand Gonseth. L'exemple de l'enseignement de la numération à l'école élémentaire.

De quels aspects tenir compte dans l'enseignement ? Selon quels critères départager ce qu'il est important de connaître, de comprendre, de ce qui n'est qu'aspect mineur ? Qu'est-ce qui mérite d'être enseigné ou de n'être qu'évoqué, en classe, si l'occasion se présente, ou encore qui ne mérite pas de mention? Quelle attitude et prix à payer, pour rester attentif aux difficultés des élèves ? Dialogue. Mise en texte en clin d'œil à Gonseth. Propos à partir d'un mémoire d'étudiante portant sur l'enseignement de la numération à l'école primaire, et en relation avec l'ouvrage de J. F. Perret: Comprendre l'écriture des nombres. (Berne, Peter Lang 1985), discussion du problème de l'évidence et de la question de savoir jusqu'où l'on doit pousser l'analyse des objets d'enseignement. Hiatus entre apprentissage de la numération scolaire formel relativement peu transférable et apprentissage "sur le tas" de cette même numération

Tornado season: are you ready?

Reviewed by Conne Burnham (Emergency Management Specialist, Fire and Rescue Training Institute)"Each year, many people are killed or seriously injured by severe storms and tornadoes despite advance warning. Some didn't hear the warning, while others received the warning but did not believe a tornado would actually affect them. After you have received the warning or observed threatening skies, you must make the decision to seek shelter before the storm arrives. It could be the most important decision you will ever make."--Page 1

A Latent Variable Approach for the Construction of Continuous Health Indicators

In most health survey the state of health of individuals is measured through several different kinds of variables such as qualitative, discrete quantitative or dichotomic ones. From these variables, one aims at building univariate indices of health that summarize the information. To do so, we propose in this paper to use Generalized Linear Latent Variable Models (GLLVM) (see e.g. Bartholomew and Knott 1999), which allows to estimate one or more continuous latent variables from a set of observable ones. As an application, we consider the data from the 1997 Swiss Health Survey and build two health indicators. The first one describes the health status induced merely by the age of the subject, and the second one complements the first one.

Points de repères pour l’analyse de protocoles

En amont de l’article sur la question des formulations, Conne 1989 (« Invitation à une réflexion sur le rôle du langage dans l’enseignement des mathématiques »), propositions méthodologiques dans l’analyse didactique de protocoles d’entretiens individuels. Définition de la notion d’échange didactique et distinction dans les déclarations des élèves de ce qui a valeur d’expression de leur pensée et de ce qui a valeur de termes d’échanges avec leur interlocuteur.Entretiens individuels autour de problèmes arithmétiques, en lien avec les études menées dans les autres articles de 1985

An Associative and Noncommutative Product for the Low Energy Effective Theory of a D-Brane in Curved Backgrounds and Bi-Local Fields

We point out that when a D-brane is placed in an NS-NS B field background with non-vanishing field strength (H=dB) along the D-brane worldvolume, the coordinate of one end of the open string does not commute with that of the other in the low energy limit. The degrees of the freedom associated with both ends are not decoupled and accordingly, the effective action must be quite different from that of the ordinary noncommutative gauge theory for a constant B background. We construct an associative and noncommutative product which operates on the coordinates of both ends of the string and propose a new type of noncommutative gauge action for the low energy effective theory of a Dp-brane. This effective theory is bi-local and lives in twice as large dimensions (2D=2(p+1)) as in the H=0 case. When viewed as a theory in the D-dimensional space, this theory is non-local and we must force the two ends of the string to coincide. We will then propose a prescription for reducing this bi-local effective action to that in D dimensions and obtaining a local effective action.Comment: 23 pages, LaTeX2e, 1 figur

Distracting people from sources of discomfort in a simulated aircraft environment

BACKGROUND: Comfort is an important factor in the acceptance of transport systems. In 2010 and 2011, the European Commission (EC) put forward its vision for air travel in the year 2050 which envisaged the use of in-flight virtual reality. This paper addressed the EC vision by investigating the effect of virtual environments on comfort. Research has shown that virtual environments can provide entertaining experiences and can be effective distracters from painful experiences. OBJECTIVE: To determine the extent to which a virtual environment could distract people from sources of discomfort. METHODS: Experiments which involved inducing discomfort commonly experienced in-flight (e.g. limited space, noise) in order to determine the extent to which viewing a virtual environment could distract people from discomfort. RESULTS: Virtual environments can fully or partially distract people from sources of discomfort, becoming more effective when they are interesting. They are also more effective at distracting people from discomfort caused by restricted space than noise disturbances. CONCLUSIONS: Virtual environments have the potential to enhance passenger comfort by providing positive distractions from sources of discomfort. Further research is required to understand more fully the reasons why the effect was stronger for one source of discomfort than the other

Regulatory Variation at Glypican-3 Underlies a Major Growth QTL in Mice

The genetic basis of variation in complex traits remains poorly understood, and few genes underlying variation have been identified. Previous work identified a quantitative trait locus (QTL) responsible for much of the response to selection on growth in mice, effecting a change in body mass of approximately 20%. By fine-mapping, we have resolved the location of this QTL to a 660-kb region containing only two genes of known function, Gpc3 and Gpc4, and two other putative genes of unknown function. There are no non-synonymous polymorphisms in any of these genes, indicating that the QTL affects gene regulation. Mice carrying the high-growth QTL allele have approximately 15% lower Gpc3 mRNA expression in kidney and liver, whereas expression differences at Gpc4 are non-significant. Expression profiles of the two other genes within the region are inconsistent with a factor responsible for a general effect on growth. Polymorphisms in the 3′ untranslated region of Gpc3 are strong candidates for the causal sequence variation. Gpc3 loss-of-function mutations in humans and mice cause overgrowth and developmental abnormalities. However, no deleterious side-effects were detected in our mice, indicating that genes involved in Mendelian diseases also contribute to complex trait variation. Furthermore, these findings show that small changes in gene expression can have substantial phenotypic effects

Functional Polymorphisms Associated with Disease-Free Survival in Resected Carcinoma of the Esophagus

Purpose: The aim of this study was to determine whether clinical outcome after surgical resection of esophageal adenocarcinoma (EAC) or esophageal squamous cell carcinoma (ESCC) could be predicted by functional polymorphisms in different proto-oncogenes and tumor suppressor genes. Experimental De