Using an Hebbian learning rule for multi-class SVM classifiers.

http://journals.kluweronline.com/article.asp?PIPS=5384399Regarding biological visual classification, recent series of experiments have enlighten the fact that data classification can be realized in the human visual cortex with latencies of about 100-150 ms, which, considering the visual pathways latencies, is only compatible with a very specific processing architecture, described by models from Thorpe et al. Surprisingly enough, this experimental evidence is in coherence with algorithms derived from the statistical learning theory. More precisely, there is a double link: on one hand, the so-called Vapnik theory offers tools to evaluate and analyze the biological model performances and on the other hand, this model is an interesting front-end for algorithms derived from the Vapnik theory. The present contribution develops this idea, introducing a model derived from the statistical learning theory and using the biological model of Thorpe et al. We experiment its performances using a restrained sign language recognition experiment. This paper intends to be read by biologist as well as statistician, as a consequence basic material in both fields have been reviewed

Simulation neuronale de la vision précoce corticale avec un modèle de Heeger

Une simulation neuronale des cartes corticales des aires V1 impliquées dans les mécanismes de vision précoce (tel que la détection de contour) est reportée ici. Le modèle biologiquement plausible sous-jacent est un modèle de Heeger \cite{boyton-engel-etal:96,simoncelli-heeger:98}. Il a été récemment proposé pour rendre compte de manière plus générale du fonctionnement de ces opérateurs spatio-temporels, que ce que les travaux historiques de Hubel et Wiesel proposaient \cite{hubel-wiesel:- 77,hubel:94}. Notre développement logiciel est basé sur un logiciel libre qui propose une boite à outil pour la simulation de réseaux de neurones permettant de concevoir à la fois des architectures et des modèles neuronaux variés. Notre ajout à été d'impléme- nter les neurones "à-la" Heeger et d'expérimenter une architecture représentan- t les voies visuelles pré-corticales et l'aire corticale V1, sous la restricti- on d'une vision monoculaire et monochromatique. L'interface logiciel réalisée permet aussi de générer des stimulus correspondant à ce qui est usuellement utilisé en neurophysiologie pour de futures comparaison- s entre cette simulation et des données expérimentales effectives

A deterministic biologically plausible classifier

Considering the «data classification» problem it is known that efficient classifiers only consider a few (pertinent) parameters. This seems in contradiction with usual biological plausible models, based on neuronal networks, which intrinsically have a lot of parameters. Here, we propose to solve this apparent contradiction, building a link between biological plausible models and classifiers with low Vapnik-Chernovenkis dimension. The -somehow very simple- key idea is to consider piece-wise linear classifiers of minimal dimension, as a generalization of support-vector machine. This allows to solve the previous dilemma at both a theoretical and computational levels, including some elements of biological plausibility. Experimentation of a small interactive toy demonstration to analyze the performances of these mechanisms is reported, while the methodology is validated on a real experimental problems

Accompagner des étudiant·e·s qui travaillent en groupe

Comprend des références bibliographiquesDe nombreux enseignements recourent aujourd’hui aux travaux de groupes pour développer les acquis d’apprentissage d’un programme ou d’une formation. Le travail collaboratif repose sur la mise en œuvre d’une pédagogie active, de nature socioconstructiviste, dans laquelle les étudiant·e·s contribuent non seulement à leur propre apprentissage (elles et ils construisent les connaissances plutôt qu’elles et ils ne les reçoivent), mais aussi à l’apprentissage de leurs pairs, grâce aux discussions sur la tâche à accomplir. En plus de soutenir le développement de savoirs disciplinaires, l’apprentissage collaboratif favorise l’acquisition d’habiletés transversales très recherchées dans les milieux professionnels (capacité à travailler en groupe, à s’exprimer avec logique et clarté, à assumer des responsabilités, à exercer une pensée critique, notamment). Si cette modalité d’apprentissage est de plus en plus plébiscitée dans les formations universitaires, sa mise en place pose toutefois une série de problèmes pratiques. Comment, par exemple, tenir compte, au moment de l’évaluation d’un travail de groupe, des passagères et passagers clandestin·e·s, ces étudiant·e·s qui se reposent sur le travail de leurs pairs ? Comment initier une dynamique de groupe propice à l’apprentissage ? L’enseignant doit-il/elle se préoccuper des conflits relationnels qui surgissent parfois au sein des équipes d’étudiant·e·s ? Ce cahier se propose d’offrir quelques pistes de résolutions à ces questions. Il s’appuie sur les travaux qu’une communauté d’apprentissage et de recherche a menés sur la thématique de l’accompagnement des groupes d’apprentissage entre mai 2015 et 2017, avec le soutien du Fonds de Développement Pédagogique de l’Université (FDP2). Ancré dans des pratiques enseignantes de plusieurs facultés, étayé par des recherches scientifiques, ce guide vise à faciliter le travail des enseignant·e·s qui souhaiteraient à leur tour accompagner des équipes d’étudiant·e·s dans leurs formations

Phase Change Material Device for Spacecraft Thermal Control

On board a satellite, the experiments and subsystems have to be maintained within specified temperature limits. Phase Change Materials (PCM) offer the possibility to store thermal energy directly as latent heat of fusion. Usually, the melting PCM can easily be used in reversible, closed systems. Two advantages of a PCM device are the stability of temperature control and the absence of moving parts. The heat-storage requirement is mainly defined by the duty cycle along the orbital period. A trade-off is presented for typical missions, which takes into account the temperature range, the weight and thermal conductivity of the PCM device together with the specific design of the container. Candidates PCM for space applications are reviewed according to their main characteristics such as latent heat, phase transition temperature, conductivity, density but also corrosion potential, hysteresis and ageing. Potential weight and power gains are finally presented for selected missions

Provision of medical supply kits to improve quality of antenatal care in Mozambique: a stepped-wedge cluster randomised trial

Background High levels of maternal and newborn mortality and morbidity remain a daunting reality in many low-income countries. Several interventions delivered during antenatal care have been shown to improve maternal and newborn outcomes, but stockouts of medical supplies at point of care can prevent implementation of these services. We aimed to evaluate whether a supply chain strategy based on the provision of kits could improve quality of care. Methods We did a pragmatic, stepped-wedge, cluster-randomised controlled trial at ten antenatal care clinics in Mozambique. Clinics were eligible if they were not already implementing the proposed antenatal care package; they served at least 200 new pregnant women per year; they had Maternal and Child Health (MCH) nurses; and they were willing to participate. All women attending antenatal care visits at the participating clinics were included in the trial. Participating clinics were randomly assigned to shift from control to intervention on prespecified start dates. The intervention involved four components (kits with medical supplies, a cupboard to store these supplies, a tracking sheet to monitor stocks, and a one-day training session). The primary outcomes were the proportion of women screened for anaemia and proteinuria, and the proportion of women who received mebendazole in the first antenatal care visit. The intervention was delivered under routine care conditions, and analyses were done according to the intention-to-treat principle. This trial is registered with the Pan African Clinical Trial Registry, number PACTR201306000550192. Findings Between March, 2014, and January, 2016, 218 277 antenatal care visits were registered, with 68 598 first and 149 679 follow-up visits. We found significant improvements in all three primary outcomes. In first visits, 5519 (14·6%) of 37 826 women were screened for anaemia in the control period, compared with 30 057 (97·7%) of 30 772 in the intervention period (adjusted odds ratio 832·40; 99% CI 666·81–1039·11; p<0·0001); 3739 (9·9%) of 37 826 women were screened for proteinuria in the control period, compared with 29 874 (97·1%) of 30 772 in the intervention period (1875·18; 1447·56–2429·11; p<0·0001); and 17 926 (51·4%) of 34 842 received mebendazole in the control period, compared with 24 960 (88·2%) of 28 294 in the intervention period (1·88; 1·70–2·09; p<0·0001). The effect was immediate and sustained over time, with negligible heterogeneity between sites. Interpretation A supply chain strategy that resolves stockouts at point of care can result in a vast improvement in quality during antenatal care visits, when compared with the routine national process for procurement and distribution of supplies. Funding Government of Flanders and the UNDP/UNFPA/UNICEF/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction.Fil: Betrán, Ana Pilar. Organizacion Mundial de la Salud; ArgentinaFil: Bergel, Eduardo. World Health Organization; Suiza. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Griffin, Sally. International Centre For Reproductive Health; MozambiqueFil: Melo, Armando. Mozambique Ministry Of Health; MozambiqueFil: Nguyen, My Huong. World Health Organization; SuizaFil: Carbonell, Alicia. World Health Organization; SuizaFil: Mondlane, Santos. Consultório de Estatística E Serviço de Soluções; MozambiqueFil: Merialdi, Mario. World Health Organization; SuizaFil: Temmerman, Marleen. World Health Organization; SuizaFil: Gülmezoglu, A Metin. World Health Organization; SuizaFil: Aleman, Alicia. World Health Organization; SuizaFil: Althabe, Fernando. World Health Organization; Suiza. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Biza, Adriano. World Health Organization; SuizaFil: Crahay, Beatrice. World Health Organization; SuizaFil: Chavane, Leonardo. World Health Organization; SuizaFil: Colomar, Mercedes. World Health Organization; SuizaFil: Delvaux, Therese. World Health Organization; SuizaFil: Dique Ali, Ussumane. World Health Organization; SuizaFil: Fersurela, Lucio. World Health Organization; SuizaFil: Geelhoed, Diederike. World Health Organization; SuizaFil: Jille-Taas, Ingeborg. World Health Organization; SuizaFil: Malapende, Celsa Regina. World Health Organization; SuizaFil: Langa, Célio. World Health Organization; SuizaFil: Osman, Nafissa Bique. World Health Organization; SuizaFil: Requejo, Jennifer. World Health Organization; SuizaFil: Timbe, Geraldo. World Health Organization; Suiz

The benefits and challenges of creative writing assessment in French: Un geste pour un autre by Jean Tardieu

This article aims to highlight and defend the benefits of creative writing assessment in higher education language modules. While the latter traditionally prefer essay-like assignments over creative ones, creative writing allows learners to develop a great variety of academic and personal skills, such as intercultural awareness, cooperation, problem-solving, engagement with literary texts and self-expression. Specifically, this article analyses a written assignment that was given in a post-A-level French module at a British University based on the French playwright Jean Tardieu’s short comedy Un geste pour un autre. Learners received the beginning of this absurdist play and needed to complete it, while also incorporating three lines from the original play into their texts. The task invited them to demonstrate their understanding of theatrical conventions, engagement with the original extract, ability to write a coherent text, language skills (grammar, syntax, vocabulary, register), linguistic innovation, imagination and problem-solving. In addition to exploring the strategies used by learners to cope with the task, this paper highlights the challenges encountered by evaluators to mark creative writing assignments, notably the lack of suitable assessment criteria in their institutions. It also examines students’ reception to such an unusual language assignment and offers some suggestions about how to better implement creative activities in the language curriculum

Opportunities to improve postpartum care for mothers and infants: design of context-specific packages of postpartum interventions in rural districts in four sub-Saharan African countries

Background: Postpartum maternal and infant mortality is high in sub-Saharan Africa and improving postpartum care as a strategy to enhance maternal and infant health has been neglected. We describe the design and selection of suitable, context-specific interventions that have the potential to improve postpartum care. Methods: The study is implemented in rural districts in Burkina Faso, Kenya, Malawi and Mozambique. We used the four steps ‘systems thinking’ approach to design and select interventions: 1) we conducted a stakeholder analysis to identify and convene stakeholders; 2) we organised stakeholders causal analysis workshops in which the local postpartum situation and challenges and possible interventions were discussed; 3) based on comprehensive needs assessment findings, inputs from the stakeholders and existing knowledge regarding good postpartum care, a list of potential interventions was designed, and; 4) the stakeholders selected and agreed upon final context-specific intervention packages to be implemented to improve postpartum care. Results: Needs assessment findings showed that in all study countries maternal, newborn and child health is a national priority but specific policies for postpartum care are weak and there is very little evidence of effective postpartum care implementation. In the study districts few women received postpartum care during the first week after childbirth (25 % in Burkina Faso, 33 % in Kenya, 41 % in Malawi, 40 % in Mozambique). Based on these findings the interventions selected by stakeholders mainly focused on increasing the availability and provision of postpartum services and improving the quality of postpartum care through strengthening postpartum services and care at facility and community level. This includes the introduction of postpartum home visits, strengthening postpartum outreach services, integration of postpartum services for the mother in child immunisation clinics, distribution of postpartum care guidelines among health workers and upgrading postpartum care knowledge and skills through training. Conclusion: There are extensive gaps in availability and provision of postpartum care for mothers and infants. Acknowledging these gaps and involving relevant stakeholders are important to design and select sustainable, context-specific packages of interventions to improve postpartum care