Evaluation participative de nouvelles variétés de sorgho au Burkina

Au Burkina Faso, le sorgho représente plus de la moitié de la production céréalière et constitue l'aliment de base des populations rurales. En raison de la faible diffusion des variétés sélectionnées de sorgho développées par la recherche depuis plus de trente ans, un nouveau schéma d'amélioration variétale du sorgho, impliquant plus tôt les agriculteurs dans l'évaluation des nouvelles lignées développées, a été proposé, basé notamment sur des tests d'évaluation variétale participative (EVP) en milieu réel sous gestion paysanne. La démarche suivie pour ces tests EVP et les premiers résultats obtenus pour la zone nord-soudanienne du Burkina sont ici présentés et discutés. Dans les conditions de bonne fertilité, les matériels sélectionnés caudatum ont donné les meilleurs résultats de rendement et ont été bien appréciés par les agriculteurs pour la valeur agronomique et la qualité des grains. Dans les conditions de faible fertilité, les variétés et lignées guinea, ont été, dans l'ensemble. les plus performantes et préférées par les paysans pour leur rusticité, leur productivité et leur qualité de grain. Des fortes concordances ont été mises en évidence entre les appréciations des agriculteurs et du sélectionneur pour les caractères de précocité, de rendement grain et de valeur agronomique générale, avec toutefois des divergences suivant les conditions d'évaluation. Pour l'ensemble des situations, 14 variétés différentes ont été retenues par les agriculteurs pour une validation en grandes parcelles au lieu de trois ou quatre proposées par la recherche dans un schéma de sélection-évaluation-validation conventionnel. Les variétés Sariaso 14, Sariaso 13, Cirad 406 et Kaapelga sont celles qui ont obtenu les meilleurs résultats d'acceptation. Des dynamiques intéressantes d'adoption et de diffusion des variétés sont en cours dans certains villages sites. Les limites du dispositif, dans les domaines de la concertation avec les organisations paysannes et de l'exploitation des interactions génotypes x environnement durant le processus de sélection ont contribué à la définition d'un nouveau projet de recherches sur la préservation de l'agrobiodi vers ité du sorgho in situ au Mali et au Burkina par l'amélioration participative des écotypes locaux. (Résumé d'auteur

Computer programming in the UK undergraduate mathematics curriculum

This paper reports a study which investigated the extent to which undergraduatemathematics students in the United Kingdom are currently taught to programme a computer as a core part of their mathematics degree programme. We undertook an online survey, with significant follow up correspondence, to gather data on current curricula and received replies from 46 (63%) of the departments who teach a BSc mathematics degree. We found that 78% of BSc degree courses in mathematics included computer programming in a compulsory module but 11% of mathematics degree programmes do not teach programming to all their undergraduate mathematics students. In 2016 programming is most commonly taught to undergraduate mathematics students through imperative languages, notably MATLAB, using numerical analysis as the underlying (or parallel) mathematical subject matter. Statistics is a very popular choice in optional courses, using the package R. Computer algebra systems appear to be significantly less popular for compulsory first year coursesthan a decade ago, and there was no mention of logic programming, functional programming or automatic theorem proving software. The modal form of assessment of computing modules is entirely by coursework (i.e. no examination)

Bridging knowing and proving in mathematics An essay from a didactical perspective

Text of a talk at the conference "Explanation and Proof in Mathematics: Philosophical and Educational Perspective" held in Essen in November 2006International audienceThe learning of mathematics starts early but remains far from any theoretical considerations: pupils' mathematical knowledge is first rooted in pragmatic evidence or conforms to procedures taught. However, learners develop a knowledge which they can apply in significant problem situations, and which is amenable to falsification and argumentation. They can validate what they claim to be true but using means generally not conforming to mathematical standards. Here, I analyze how this situation underlies the epistemological and didactical complexities of teaching mathematical proof. I show that the evolution of the learners' understanding of what counts as proof in mathematics implies an evolution of their knowing of mathematical concepts. The key didactical point is not to persuade learners to accept a new formalism but to have them understand how mathematical proof and statements are tightly related within a common framework; that is, a mathematical theory. I address this aim by modeling the learners' way of knowing in terms of a dynamic, homeostatic system. I discuss the roles of different semiotic systems, of the types of actions the learners perform and of the controls they implement in constructing or validating knowledge. Particularly with modern technological aids, this model provides a basis designing didactical situations to help learners bridge the gap between pragmatics and theory

Digital technologies in the early primary school classroom

Papert’s (1980) work with Turtle Geometry offered an early and provocative vision of how digital technologies could be used with young learners. Since then, research on digital technology use has focused on the middle and high school levels (notable exceptions include Sarama & Clements, 2002; Hoyles, Noss & Adamson, 2002). Given the increasing diversity of digital technologies, and their varied underlying pedagogical goals and design choices, Clements’ (2002) claim that “there is no single effect of the computer on mathematics achievement” (p. 174) is as true now as it was a decade ago. However, many advances have been made in better articulating the range of design choices that are possible, their potential effect on the cognitive and affective dimensions on mathematics learning, and their varying demands on the teacher. The aim of this chapter is to summarise the research literature on the use of digital technologies in the teaching and learning of mathematics at the k-2 level. In particular, we focus on literature that contributes to our understanding of how the use of digital technologies affects and changes the teaching and learning of mathematics—that is, how different affordances and design choices impact on the way teachers and learners interact and express themselves mathematically. By digital technologies we refer to a range of tools including multi-purpose computer-based software programs, web-based applets, virtual manipulatives, programming languages, CD-ROMs, games, calculators, touchscreen applications and interactive whiteboards. The distinction between these various types is not always evident [1] and, indeed, one goal of this chapter is to provide useful distinguishing features of these various technologies in order to help educators better evaluate and choose amongst them. We begin by outlining some of the major theoretical developments that are shaping the way researchers are studying the use of digital technologies; we hope that some of these developments, which originate in research conducted for the middle and high school grades, can inform research at the younger grade levels, thus building on decades-old insights and constructs. We then present an overview of research related first to two content areas of the primary school curriculum—number sense and geometry—and second to a mix of content areas all approached through the use of programming languages. Where possible, we try to describe the particular affordances of the digital technology involved, that is, the kinds of interactions that can be performed, acknowledging that intended affordances may not always be perceived as possible by users [2]. We are also aware of the fact that many of the tools we describe may quickly disappear, to be replaced by new interpretations or available on new platforms. We have thus tried to focus attention on the design principles that may have relevance beyond specific examples. At the end of the chapter we discuss several themes that emerge from our survey of the literature and recommend future research directions

Integrating new memories into the hippocampal network activity space

By investigating the topology of neuronal co-activity, we found that mnemonic information spans multiple operational axes in the mouse hippocampus network. High-activity principal cells form the core of each memory along a first axis, segregating spatial contexts and novelty. Low-activity cells join co-activity motifs across behavioral events and enable their crosstalk along two other axes. This reveals an organizational principle for continuous integration and interaction of hippocampal memories

New sources of resistance to sorghum midge in Burkina Faso

New sources of midge (Stenodiplosis sorghicola) resistance among local Sorghum bicolor cultivars were determined in experiments carried out from 1996-99 in Burkina Faso. Two hundred local landraces from Burkina Faso and other West African countries were screened for midge resistance. The 40 best cultivars were tested with resistant and susceptible controls during the 1999 rainy seasons, in midge-infested sites Kouaré and Farako-Bâ. The average percentage of midge-damaged spikelets in Kouaré varied from 0% in ICSV 745 to 45.3% in susceptible landrace 439. At Farako-Bâ, the percentage of damaged spikelets varied from 0.4% in ICSV 745 to 31.8% on the susceptible control Sariaso 10. Cultivar Tenlopieno had the highest percentage of damaged spikelets in both locations, but showed low visual midge damage scores

The histone demethylase JMJD2A/KDM4A links ribosomal RNA transcription to nutrients and growth factors availability

The interplay between methylation and demethylation of histone lysine residues is an essential component of gene expression regulation and there is considerable interest in elucidating the roles of proteins involved. Here we report that histone demethylase KDM4A/JMJD2A, which is involved in the regulation of cell proliferation and is overexpressed in some cancers, interacts with RNA Polymerase I, associates with active ribosomal RNA genes and is required for serum-induced activation of rDNA transcription. We propose that KDM4A controls the initial stages of transition from 'poised', non-transcribed rDNA chromatin into its active form. We show that PI3K, a major signalling transducer central for cell proliferation and survival, controls cellular localization of KDM4A and consequently its association with ribosomal DNA through the SGK1 downstream kinase. We propose that the interplay between PI3K/SGK1 signalling cascade and KDM4A constitutes a mechanism by which cells adapt ribosome biogenesis level to the availability of growth factors and nutrients

TDP1 mutation causing SCAN1 neurodegenerative syndrome hampers the repair of transcriptional DNA double-strand breaks

TDP1 removes transcription-blocking topoisomerase I cleavage complexes (TOP1ccs), and its inactivating H493R mutation causes the neurodegenerative syndrome SCAN1. However, the molecular mechanism underlying the SCAN1 phenotype is unclear. Here, we generate human SCAN1 cell models using CRISPR-Cas9 and show that they accumulate TOP1ccs along with changes in gene expression and genomic distribution of R-loops. SCAN1 cells also accumulate transcriptional DNA double-strand breaks (DSBs) specifically in the G1 cell population due to increased DSB formation and lack of repair, both resulting from abortive removal of transcription-blocking TOP1ccs. Deficient TDP1 activity causes increased DSB production, and the presence of mutated TDP1 protein hampers DSB repair by a TDP2-dependent backup pathway. This study provides powerful models to study TDP1 functions under physiological and pathological conditions and unravels that a gain of function of the mutated TDP1 protein, which prevents DSB repair, rather than a loss of TDP1 activity itself, could contribute to SCAN1 pathogenesis