Self-Optimizing Mechanisms for EMF Reduction in Heterogeneous Networks

This paper focuses on the exposure to Radio Frequency (RF) Electromagnetic Fields (EMF) and on optimization methods to reduce it. Within the FP7 LEXNET project, an Exposure Index (EI) has been defined that aggregates the essential components that impact exposure to EMF. The EI includes, among other, downlink (DL) exposure induced by the base stations (BSs) and access points, the uplink (UL) exposure induced by the devices in communication, and the corresponding exposure time. Motivated by the EI definition, this paper develops stochastic approximation based self-optimizing algorithm that dynamically adapts the network to reduce the EI in a heterogeneous network with macro- and small cells. It is argued that the increase of the small cells' coverage can, to a certain extent, reduce the EI, but above a certain limit, will deteriorate DL QoS. A load balancing algorithm is formulated that adapts the small cell' coverage based on UL loads and a DL QoS indicator. The proof of convergence of the algorithm is provided and its performance in terms of EI reduction is illustrated through extensive numerical simulations

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

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

Reducing the oral quinine-quinidine-cinchonin (Quinimax) treatment of uncomplicated malaria to three days does not increase the recurrence of attacks among children living in a highly endemic area of Senegal

A 3 d shortened course of the quinine-quinidine-cinchonin association Quinimax (trademark) was compared to the usual 7 d regimen for routinely treating 462 acute uncomplicated #Plasmodium falciparum$malaria attacks in 72 children under the age of 10 years in Dielmo, a holoendemic village in Senegal. 25 mg/kg Quinimax (trademark) salt daily, given in 3 equal doses, improved clinical status in 99.6$ and the partial acquired immunity of the children were probably responsible for the absence of any difference between the courses. Oral Quinimax (trademark) for 3 d is a possible alternative regimen to chloroquine and sulfadoxine-pyrimethamine for treating uncomplicated malaria in highly endemic areas of Africa where clinical resistance to these drugs exists. (Résumé d'auteur

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

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

Identification d'une nouvelle salmonelle multirésistante dans une viande de poulet de chair au Sénégal

L'analyse microbiologique d'une carcasse de poulet de chair au Sénégal a permis de mettre en évidence un nouveau sérotype de salmonelle. Celui-ci présente la particularité de posséder deux gènes de résistance aux antibiotiques ; il n'est sensible qu'aux quinolones de dernière génération. L'existence de ce nouveau sérotype est inquiétante parce qu'il a été retrouvé dans des prélèvements humains, associé à de l'hyperthermie et de la diarrhée profuse. L'apparition d'une telle salmonelle peut éventuellement s'expliquer par l'utilisation anarchique des antibiotiques dans l'élevage des volailles. (Résumé d'auteur

Diagnosing students' difficulties in learning mathematics

This study considers the results of a diagnostic test of student difficulty and contrasts the difference in performance between the lower attaining quartile and the higher quartile. It illustrates a difference in qualitative thinking between those who succeed and those who fail in mathematics, illustrating a theory that those who fail are performing a more difficult type of mathematics (coordinating procedures) than those who succeed (manipulating concepts). Students who have to coordinate or reverse processes in time will encounter far greater difficulty than those who can manipulate symbols in a flexible way. The consequences of such a dichotomy and implications for remediation are then considered

Stevin numbers and reality

We explore the potential of Simon Stevin's numbers, obscured by shifting foundational biases and by 19th century developments in the arithmetisation of analysis.Comment: 22 pages, 4 figures. arXiv admin note: text overlap with arXiv:1104.0375, arXiv:1108.2885, arXiv:1108.420