Scaling Up Climate Services for Farmers in Africa and South Asia: Workshop Report

This report summarizes the proceedings of the workshop “Scaling Up Climate Services for Farmers in Africa and South Asia,” held in Saly, Senegal on December 10-12, 2012. The workshop brought together more than 100 experts from 30 countries and roughly 50 institutions to grapple with the challenge of supporting vulnerable farming communities through the production, communication, delivery and evaluation of effective agrometeorological information and advisory services; and to identify practical actions to address those challenges at scale

Morbidité et létalité palustres dans un service de pédiatrie en Afrique de l'Ouest

Le paludisme est à l'origine de 30 % des hospitalisations dans le service de pédiatrie de l'hôpital de Bobo-Dioulasso (Burkina Faso), avec une grande variation de fréquence au cours de l'année : 11 % des hospitalisations en saison sèche, 43 % en période de transmission palustre. Avec un taux de létalité de 7 %, le paludisme est directement responsable de 15 % des décès des enfants hospitalisés. (Résumé d'auteur

An experimental and modelling study of dual fuel aqueous ammonia and diesel combustion in a single cylinder compression ignition engine

The ability of ammonia to act as a hydrogen carrier, without the drawbacks of hydrogen gas-storage costs and low stability-renders it a potential solution to the decarbonisation of transport. This study combines both modelling and experimental techniques to determine the effect of varying the degree of aspiration of ammonium hydroxide (NH4OH) solution, at different engine loads, in the combustion of a compression ignition engine. Ignition delay was extended as ammonia injection increased, causing an increase in peak in-cylinder temperature, but generally lower combustion quality-increasing incomplete combustion products, while decreasing particle size. The higher peak in-cylinder temperatures generally correlated with a higher nitrous oxide (NOx) emissions in the exhaust, though fuel-bound nitrogen effect was apparent. Chemical kinetic modelling at equivalent conditions found increasing levels of unburnt ammonia with greater aspiration. Moreover, the ignitability of NH4OH was found to improve in simulations substituting diesel with hydrogen peroxide direct injection

Students’ Evolving Meaning About Tangent Line with the Mediation of a Dynamic Geometry Environment and an Instructional Example Space

In this paper I report a lengthy episode from a teaching experiment in which fifteen Year 12 Greek students negotiated their definitions of tangent line to a function graph. The experiment was designed for the purpose of introducing students to the notion of derivative and to the general case of tangent to a function graph. Its design was based on previous research results on students’ perspectives on tangency, especially in their transition from Geometry to Analysis. In this experiment an instructional example space of functions was used in an electronic environment utilising Dynamic Geometry software with Function Grapher tools. Following the Vygotskian approach according to which students’ knowledge develops in specific social and cultural contexts, students’ construction of the meaning of tangent line was observed in the classroom throughout the experiment. The analysis of the classroom data collected during the experiment focused on the evolution of students’ personal meanings about tangent line of function graph in relation to: the electronic environment; the pre-prepared as well as spontaneous examples; students’ engagement in classroom discussion; and, the role of researcher as a teacher. The analysis indicated that the evolution of students’ meanings towards a more sophisticated understanding of tangency was not linear. Also it was interrelated with the evolution of the meaning they had about the inscriptions in the electronic environment; the instructional example space; the classroom discussion; and, the role of the teacher

The fundamental cycle of concept construction underlying various theoretical frameworks

In this paper, the development of mathematical concepts over time is considered. Particular reference is given to the shifting of attention from step-by-step procedures that are performed in time, to symbolism that can be manipulated as mental entities on paper and in the mind. The development is analysed using different theoretical perspectives, including the SOLO model and various theories of concept construction to reveal a fundamental cycle underlying the building of concepts that features widely in different ways of thinking that occurs throughout mathematical learning