Numerical representations and technologies: possibilities from a configuration formed by teachers-with-GeoGebra

This paper reports a qualitative research whose subjects were a group of public basic education teachers who took part in a workshop approaching, as its main subjects, primality of positive integers and the Fundamental Theorem of Arithmetic, relevant topics in the number theory, dealt with from different technological perspectives and analysed under a theoretical proposal connected to the concepts of transparency and opacity of numerical representations and to the construct humans-with-media. The session where interactions occurred took place in a computing lab, in the framework of the Study Program for Post Graduates in Mathematics Education at PUC university, in São Paulo, and it consisted of two activities: during the first one, participants had to tell, from a specific representation, if a given positive integer would be prime or not; during the second one, teachers used an application from GeoGebra to determine, through different representations, which numbers in a random list would be prime. The analysis showed that participants had difficulties in the mobilization of knowledge related to the FTA, which led them to adopt strategies with a high cognitive cost and make mistakes. Likewise, data showed that similar hindrances were overcome on the basis of the educational proposal planned from a configuration of human-beings-with-GeoGebra

Intérêt des anti-oxydants dans l’alimentation des carnivores domestiques

La démonstration de l’implication du stress oxydatif dans les maladies dégénératives a conduit à supplémenter systématiquement les aliments des carnivores domestiques avec des molécules à action anti-oxydante. Les antioxydants exogènes améliorent globalement la réponse immunitaire en l’orientant vers des mécanismes à médiation cellulaire. De plus, plusieurs études ont effectivement montré, d’une part, l’existence d’une relation entre un déficit des systèmes anti-oxydants et l’installation de lésions dégénératives, et, d’autre part, que l’extension des lésions cellulaires lors d’arthrose, de cardiomyopathies et de cancer, ainsi que lors de dysfonctionnement cognitif et de cataracte chez le vieux chien, pouvait être limitée par une supplémentation en anti-oxydants. Néanmoins, l’optimisation de l’efficacité d’une telle pratique nécessite la prise en compte de facteurs individuels de sensibilité aux anti-oxydants (sexe, âge, race, statut endogène en anti-oxydants…), ainsi que la connaissance de leur métabolisme (biodisponibilité, distribution, catabolisme), de leur mode d’action (actions synergiques) et de leurs propriétés oxydo-réductrices afin de limiter l’apparition d’une éventuelle toxicité à de fortes doses. Malgré l’essor des travaux de recherche dans ce domaine, les conditions d’utilisation des anti-oxydants restent mal définies

Synthesis of novel room temperature chiral ionic liquids. application as reaction media for the heck arylation of aza-endocyclic acrylates.

New achiral and chiral RTILs were prepared using novel and/or optimized synthetic routes. These new series of imidazolinium, imidazolium, pyridinium and nicotine-derived ionic liquids were fully characterized including differential scanning calorimetry (DSC) analysis. The performance of these achiral and chiral room temperature ionic liquids (RTILs) was demonstrated by means of the Heck arylation of endocyclic acrylates employing arenediazonium salts and aryl iodides. The Heck arylations performed in the presence of these ionic entities, either as a solvent or as an additive, were effective leading to complete conversion of the substrate and good to excellent yield of the Heck adduct. In spite of the good performances, no asymmetric induction was observed in any of the cases studied. Two new diastereoisomeric NHC-palladium complexes were prepared in good yields from a chiral imidazolium salt and their structure characterized by X-ray diffraction. Overall, the Heck arylations employing arenediazonium tetrafluoroborates in RTILs were more effective than the traditional protocols employing aryl iodides in terms of reactivity and yields

La capture du Grand-Morin par la Marne (Bassin parisien, France) : âge et mécanisme

Des sondages, réalisés dans la vallée aval abandonnée du Grand-Morin, à l'ouest d'EsbIy, permettent de dater son abandon du Tardiglaciaire (Dryas ancien probable). La capture qui en est la cause est attribuée à un chenal de la Marne qui divaguait sur un lit exhaussé par les alluvions pléniglaciaires et tardiglaciaires. Elle a toutefois été préparée par un travail des deux rivières, dont les méandres s'étaient progressivement rapprochés durant le Pleistocene moyen.Drillings were undertaken in the fossil lower valley of the Grand-Morin river near Esbly. They date its piracy by the Marne river from the Late Glacial (Early Dryas probably). This capture is related to a braided channel flowing on the raised bed of Pleniglacial and Late Glacial alluvium. However, this piracy was prepared by the migration of the meanders of the two rivers during the Middle Pleistocene

PAD: A New Interactive Knowledge-Based Analog Design Approach

This paper presents a new Procedural Analog Design tool called PAD. It is a chart-based design environment dedicated to the design of analog circuits aiming to optimize design and quality by finding good tradeoffs. This interactive tool allows step-by-step design of analog cells by using guidelines for each analog topology. Its interactive interface enables instantaneous visualization of design tradeoffs. At each step, the user modifies interactively one subset of design parameters and observes the effect on other circuit parameters. At the end, an optimized design is ready for simulation (verification and fine-tuning). The present version of PAD covers the design of basic analog structures (one transistor or groups of transistors) and the procedural design of transconductance amplifiers (OTAs) and different operational amplifier topologies. The basic analog structures' calculator embedded in PAD uses the complete set of equations of the EKV MOS model, which links the equations for weak and strong inversion in a continuous way [1, 2]. Furthermore, PAD provides a layout generator for matched substructures such as current mirrors, cascode stages and differential pair

Continuous flow processing as a tool for the generation of terpene-derived monomer libraries

We report the development of a continuous flow approach for the preparation of two bio-derived monomer libraries. A small range of terpenes (ocimene, myrcene, α-terpinene, α-phellandrene, isoprene, and farnesene) have been used as the base set for the library, with the first library derived from a Diels–Alder reaction with the platform chemical maleic anhydride. The second library requires the derivatization of the first through a hydrogenation reaction. The potential for scale-up of both libraries has been demonstrated, with the Diels–Alder process delivering 10.5 grams of the product in 3 hours and the hydrogenation process delivering 10 grams of the material in 16 hours