Plasmodium vivax Malaria among Military Personnel, French Guiana, 1998–2008

We obtained health surveillance epidemiologic data on malaria among French military personnel deployed to French Guiana during 1998–2008. Incidence of Plasmodium vivax malaria increased and that of P. falciparum remained stable. This new epidemiologic situation has led to modification of malaria treatment for deployed military personnel

Integrated Heart - Coupling multiscale and multiphysics models for the simulation of the cardiac function

Mathematical modelling of the human heart and its function can expand our understanding of various cardiac diseases, which remain the most common cause of death in the developed world. Like other physiological systems, the heart can be understood as a complex multiscale system involving interacting phenomena at the molecular, cellular, tissue, and organ levels. This article addresses the numerical modelling of many aspects of heart function, including the interaction of the cardiac electrophysiology system with contractile muscle tissue, the sub-cellular activation-contraction mechanisms, as well as the hemodynamics inside the heart chambers. Resolution of each of these sub-systems requires separate mathematical analysis and specially developed numerical algorithms, which we review in detail. By using specific sub-systems as examples, we also look at systemic stability, and explain for example how physiological concepts such as microscopic force generation in cardiac muscle cells, translate to coupled systems of differential equations, and how their stability properties influence the choice of numerical coupling algorithms. Several numerical examples illustrate three fundamental challenges of developing multiphysics and multiscale numerical models for simulating heart function, namely: (i) the correct upscaling from single-cell models to the entire cardiac muscle, (ii) the proper coupling of electrophysiology and tissue mechanics to simulate electromechanical feedback, and (iii) the stable simulation of ventricular hemodynamics during rapid valve opening and closure

Etude de l'effet du conflit multicritère sur l'expression des préférenes (Une approche empirique)

Le travail de recherche présenté dans cette thèse s'inscrit dans le champ de l'aide multicritère à la décision. Ce champ concerne la décision dans un contexte où les alternatives sont jugées sous divers aspects, souvent conflictuels. Notre travail s'insère dans une approche descriptive et cherche à observer l'effet du conflit multicritère sur les préférences exprimées par le décideur. Dans un premier temps, nous proposons une définition de l'intensité du conflit multicritère entre deux alternatives puis nous nous intéressons aux préférences incomplètes et identifions deux classes de modèles de préférences incomplètes. Notre principale contribution est ensuite d'observer et analyser l'effet du conflit lors du recueil des préférences d'un décideur. Nous avons pour cela conçu et mené deux expérimentations permettant de tester le recueil de préférences à travers des comparaisons par paires, et à travers des matchings. La première expérimentation nous permet de mettre en évidence une forme d'intransitivité de l'indifférence le long des chaînes d'isopréférence. Un fort conflit multicritère conduit les sujets à exprimer des préférences incomplètes. Les résultats obtenus lors de cette expérimentation sont en cours de publication (Deparis et al. [2012]). La seconde expérimentation nous permet de montrer que les asymétries déjà observées dans la littérature en réponse à un bi-matching sont fortement amplifiées par l'effet du conflit multicritère. Nous discutons des implications de ces résultats en termes d'élicitation des préférences. Enfin, nous analysons les résultats expérimentaux au regard de la labilité des préférences qu'ils révèlent. Au-delà de cette contribution, notre thèse permet de mieux comprendre les interactions qui peuvent exister entre les approches normative, descriptive et prescriptive en décision multicritère.The research presented in this thesis lies in the field of multicriteria decision aid. This field deals with decision in a context where several aspects, usually in conflict, are considered when judging the alternatives. Our work stands in the descriptive approach and aims at observing the effect of multicriteria conflict on the preferences expressed by decision-makers. First, we propose a definition of the intensity of inter-alternative multicriteria conflict and then we consider incomplete preferences and identify two types of incomplete preference models. Our main contribution is then to observe and analyse the effect of conflict when assessing the preferences of a decision-maker. In order to do so, we designed and led two experiments allowing to test the assessment of preferences through pairwise comparisons and matchings. The first experiment allows us to exhibit an intransitivity of indifference along isopreference chains. A large multicriteria conflict leads subjects to express incomplete preferences. Results obtained from this experiment are under publication (Deparis et al. [2012]). The second experiment allows us to show that asymmetries already observed in the literature in response to bimatchings are strongly amplified by multicriteria conflict. We discuss the implications of these results on elicitation of preferences. Finally, we analyse the experimental results with regard to the lability of preferences that they reveal. Beyond this contribution, our thesis sheds a light on the interactions that exist between the normative, descriptive and prescriptive approaches in multicriteria decision-making.CHATENAY MALABRY-Ecole centrale (920192301) / SudocSudocFranceF

Investigations of Tides from the Antiquity to Laplace

International audienceTidal phenomena along the coasts were known since the prehistoric era, but a long journey of investigations through the centuries was necessary from the Greco-Roman Antiquity to the modern era to unravel in a quasi-definitive way many secrets of the ebb and flow. These investigations occupied the great scholars from Aristotle to Galileo, Newton, Euler, d'Alembert, Laplace, and the list could go on. We will review the historical steps which contributed to an increasing understanding of the tides

The effect of bi-criteria conflict on matching-elicited preferences

International audienceWe focus on multicriteria preference elicitation by matching. In this widely employed task, the decision maker (DM) is presented with two multicriteria options, a and b, and must assess the performance value on one criterion for b, left blank, so that she is indifferent between the two options. A reverse matching, which is normatively equivalent, can be created by integrating the answer to the description of b and letting the DM adjust a performance value on the previously totally specified option a. Such a procedure is called a bi-matching. Consistency requires that isopreferences resulting from the forward and backward matchings be identical, but they empirically differ in a systematic direction. In a matching task, multicriteria conflict refers to the magnitude of the advantage or disadvantage to be compensated. We investigate the effect of the multicriteria conflict, or trade-off size, on the difference of judgement between forward and backward matchings. We observed that the difference of judgement is increased both by multicriteria conflict and by asking deteriorating rather than improving judgements at both steps of the bi-matching. We derive some implications for the practice of preference elicitation

When conflict induces the expression of incomplete preferences

International audienceMulticriteria conflict arises in pairwise comparisons, where each alternative outperforms the other one on some criterion, which imposes a trade-off. Comparing two alternatives can be difficult if their respective advantages are of high magnitude (the attribute spread is large). In this paper, we investigate to which extent conflict in a comparison situation can lead decision makers to express incomplete preferences, that is, to refuse to compare the two alternatives, or to be unable to compare them with confidence. We report on an experiment in which subjects expressed preferences on pairs of alternatives involving varying conflicts. Results show that depending on whether the participants are allowed to express incomplete preferences or not, attribute spread has a different effect: a large attribute spread increases the frequency of incomparability statements, when available, while it increases the use of indifference statements when only indifference and preference answers are permitted. These results lead us to derive some implications for preference elicitation methods involving comparison tasks

Use of Capillary Blood Samples as a New Approach for Diagnosis of Dengue Virus Infection

We evaluated the use of capillary blood samples stored on filter papers for diagnosis of dengue virus infection. Venous and capillary blood samples were collected from 130 patients suspected of having dengue fever. We compared the performances of standard reference methods using capillary blood samples absorbed onto filter papers versus venous blood samples. The resulting sensitivity, specificity, and positive predictive value of tests performed on filter paper compared to those performed on venous blood samples were 81.6% (62/76; 95% confidence interval [CI], 74.9% to 88.3%), 90.7% (49/54; 95% CI, 85.7% to 95.7%), and 92.5% (62/67; 95% CI, 86.2% to 98.8%), respectively. During the acute phase of dengue virus infection (day 1 to day 4), the tests performed on capillary blood samples had a sensitivity of 88.5% (95% CI, 82.0% to 95.0%) and a specificity of 93.8% (95% CI, 88.9% to 98.7%). During the convalescent phase of infection, this method allowed the viral serotype to be determined for 4 of 15 (27%) dengue virus-infected patients for whom virological diagnosis using venous samples was negative. Capillary blood samples could therefore be a good alternative for the diagnosis of dengue virus infection in tropical areas. Indeed, these samples are convenient for storage and transport without the need for a cold chain and simplify the collection of samples from children. Moreover, our results suggest that viral particles persist longer in capillary blood than in peripheral blood. Analysis of the viability of viral particles under these conditions may give new insights into the physiopathology of dengue virus infection and the transmission of dengue virus during outbreaks