On the Interoperability of DEVS components: On-Line vs. Off-Line Strategies

During the last years, the DEVS community provides many contributions towards the realization of a world-wide platform for collaborative Modeling & Simulation. The goal of such a platform would be to enable the sharing and reuse of models between scientists, as well as the seamless simulation of distributed and heterogeneous models. Therefore, one of the major research fields is the definition of architectures for integrating heterogeneous DEVS components, meaning simulators and/or models written in different frameworks and programming languages. In this work, we present three different strategies for providing such interoperability between DEVS components. The first focuses on standardizing exchanges between simulators, and has been explored in previous works. The two others strategies are more prospective; in keeping with Model-Driven Engineering, they place the model at the center of their architecture and make extensive use of model transformations. To make this possible, we defined a platform and language-independent format for describing and sharing DEVS models, called DEVS Markup Language

Verification and Validation of D2FD Method

International audience—D2FD (Data to Fuzzy-DEVS) method provides a solution for the problem of system inference. This method is well designed and implemented as an available and dedicated plug-in within the process mining framework (ProM). This plug-in is also integrated with the simulation tool SimStudio. However, the last step of the process of inferring models and simulations, which is verification and validation, is missing. This paper proposes a new paradigm of verification and validation in system inference. The case study uses the method of comparing with other models as the main validation technique. Based on the same data source from the Dutch Employee Insurance Agency, it attempts to compare the previous results with other studies

Activity Regions for the Specication of Discrete Event Systems

International audienceThe common view on modeling and simulation of dynamic systems is to focus on the specification of the state of the system and its transition function. Although some interesting challenges remain to efficiently and elegantly support this view, we consider in this paper that this problem is solved. Instead, we propose here to focus on a new point of view on dynamic system specifications: the activity exhibited by their discrete event simulation. We believe that such a viewpoint introduces a new way for analyzing, modeling and simulating systems. We first start with the definition of the key notion of activity for the specification of a specific class of dynamic system, namely discrete event systems. Then, we refine this notion to characterize activity regions in time, in space, in states and in hierarchical component-based models. Examples are given to illustrate and stress the importance of this notion

Fréquence des néphropathies congénitales au Centre hospitalier universitaire de Donka à Conakry: Frequency of congenital nephropathies in the University Hospital of Donka in Conakry

Context and objective. The real extent of congenital nephropathies is little known in Africa and in particular in Guinea. The objective of this study was to determine the prevalence of congenital nephropathies in the University Hospital of Donka. Methods. This was a descriptive retrospective study enrolling patients admitted for congenital nephropathy at both pediatric and pediatric surgery departments of Donka, between January 1st, 2007 and June 30th, 2012. The parameters of the study were epidemiological, clinical and paraclinical data.  Results. Of 34,448 patients recorded during the period studied, 26 had congenital nephropathies. They encompassed nephroblastoma (n=17), SJPU (n=6), hydronephrosis on left multikystic kidney (n=1), multikystic kidney in ptosis (n=1) and renal ectopia (n=1). Male sex was preponderant (21/26) with a sex ratio of 4.2/1. The 29 day-old to 2 year-old children were more affected. Conclusion. Congenital nephropathies appear less frequently in this hospital probably due to the absence of optimal facilities. The early diagnosis of congenital nephropathies should be made during the antenatal time, which would be a key to a better management of these conditions in affected children. Contexte et objectif. L’ampleur réelle des néphropathies congénitales est peu connue en Afrique et notamment en Guinée. L’objectif de cette étude était de déterminer la fréquence des néphropathies congénitales rencontrées. Méthodes. Cette étude documentaire de type descriptif sur la néphropathie congénitale, a été conduite entre les 1er janvier 2007 et 30 juin 2012, dans les services de pédiatrie et de chirurgie pédiatrique de Donka. Les paramètres d’interet englobaient les données épidémiologiques, cliniques et paracliniques.  Résultats. Parmi les 34.448 dossiers colligés, 26 présentaient une néphropathie congénitale. Il s’agissait des néphroblastomes (n=17), des syndromes de jonction pyélo-urétérale (n=6), d’une hydronéphrose sur rein multikystique gauche (n=1), d’un rein multikystique en ptose (n=1) et d’une ectopie rénale (n=1). Le sexe masculin était prépondérant (21/26) avec un sexe ratio de 4,2/1. Les enfants de 29 jours à 2 ans étaient les plus touchés. Conclusion. Les néphropathies congénitales sont paraissent moins fréquentes dans cette institution hospitalière, à cause du manque d’un plateau technique diagnostique optimal. Le diagnostic précoce des néphropathies congénitales devrait être fait dans la période prénatale ce qui permettrait une meilleure prise en charge des enfants affectés

Évaluation du Risque Cardiovasculaire Absolu Chez les Patients Hémodialysés Diabétiques et Non diabétiques au Centre National d’Hémodialyse de Donka Conakry

Le risque cardiovasculaire chez les hémodialysés semble varier en fonction du statut diabétique ainsi que d’autres facteurs associés et constitue un problème de santé publique en Afrique en général et particulièrement en Guinée. Dans ce sens, l’objectif de cette étude était d’évaluer le risque de survenue d’une pathologie cardiovasculaire absolu chez les patients hémodialysés diabétiques, par rapport aux patients hémodialysés non diabétiques. La présente, étude transversale, descriptive et analytique a été réalisée entre le 1 ier avril et le 30 juin 2019 au Centre National d’Hémodialyse de Donka. L’étude a inclus les 140 patients hémodialysés durant la période. Le recrutement était exhaustif et concernait tous les patients hémodialysés répondant aux critères de sélection. Les données ont été recueillies prospectivement chez les patients hémodialysés puis compilées et traitées dans Epi info. 7.2.2.6. Un questionnaire semi-administré a été utilisé à ce fin. Pour évaluer le risque cardiovasculaire chez les patients le FRAMINGHAM RISK SCORE (FRS) a été aussi utilisé. L’enquête a concerné 140 individus dont 91 (65,00%) étaient des hommes, contre 49 (35,00%) de femmes, soit un sex- ratio de 1,86 soit 2 hommes pour une femme. L’âge moyen était de 41 ± 4,1 ans avec des extrêmes de (30 ; 74) ans. On notait une prédominance chez les hommes des facteurs de risque, pour le tabagisme. L’étude a trouvé 39 diabétiques contre 101 non diabétiques. Le risque était élevé chez 23 diabétiquessur 39 ; et 25 sur 101 des patients non diabétiques. L’étude montre qu’un patient sur quatre aurait un risque absolu élevé chez les patients non diabétiques et un patient sur deux chez les patients diabétiques. Ce risque est majoré par d’autres facteurs associés. Introduction: Cardiovascular risk in hemodialysis appears to vary depending on diabetic status and other associated factors and is a public health problem in Africa in general and particularly in Guinea. The objective of this study was to assess the risk of absolute cardiovascular disease in diabetic hemodialysis patients, compared to non-diabetic hemodialysis patients. Methods: Between April 1 and June 30, 2019, a descriptive and analytical cross-sectional study was conducted at the National Hemodialysis Centre in Donka. The study included 140 hemodialysis patients during the period. Recruitment was comprehensive and involved all hemodialysis patients meeting the selection criteria. The data were collected prospectively in hemodialysis patients and then compiled and processed in Epi info. 7.2.2.6. A semi-administered questionnaire had been used. To assess cardiovascular risk in patients, FRAMINGHAM RISK SCORE (FRS) was used. Results: The survey involved 140 individuals, 91 of whom (65.00%) 49 (35.00%) were men. sex ratio of 1.86 or 2 men per woman. The average age was 41-4.1 years with extremes of (30; 74) years. There was a predominance among men of risk factors for smoking. The study found 39 diabetics versus 101 non-diabetics. The risk was high in 23 out of 39 diabetics; and 25 out of 101 non-diabetic patients. Conclusion: The study shows that one in four patients would have a high absolute risk in diabetic and non-diabetic patients and also confirms the association of other factors that increase this risk. The survey involved 140 individuals, 91 of whom (65.00%) 49 (35.00%) were men. sex ratio of 1.86 or 2 men per woman. The average age was 41-4.1 years with extremes of (30; 74) years. There was a predominance among men of risk factors for smoking and diabetes. In our series, most of our patients had a low risk level of 56 (40%). Conclusion: This survey finds a low risk in this hemodialysis population. This should lead to strengthening strategies for preventing cardiovascular disease in this at-risk population

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Introduction to Computational Frameworks: From Heterogeneity Challenge to Integrative Levels of Organization

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Computational Frameworks – Systems, Models and Applications

International audienceComputational Frameworks: Systems, Models and Applications provides an overview of advanced perspectives that bridges the gap between frontline research and practical efforts. It is unique in showing the interdisciplinary nature of this area and the way in which it interacts with emerging technologies and techniques. As computational systems are a dominating part of daily lives and a required support for most of the engineering sciences, this book explores their usage (e.g. big data, high performance clusters, databases and information systems, integrated and embedded hardware/software components, smart devices, mobile and pervasive networks, cyber physical systems, etc.)

Special Issue: Advances on the Theory of M&S

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Spécification, Synthèse et Qualité des Modèles de Simulation à Événements Discrets

International audienceCet ouvrage se veut une contribution à une meilleure compréhension de l’évolution des modèles de simulation dans leur cycle de vie. Le conceptau cœur de cet objectif est celui de modélisation multi-analyse qui vise à conjuguer la simulation, les capacités de raisonnement symbolique, etles moyens de synthèse automatique de code, à partir d'une spécification unique. Cet effort, qui est au service de l'ingénierie modèle-centrée des systèmes complexes, est à la croisée de la théorie mathématique des systèmes dynamiques, des méthodes formelles et du génie logiciel avancé