Equivalence checking between embedded C code and corresponding Stateflow TM diagram specification

International audienceThis paper focuses on a cost-effective application of model-checking in Verification & Validation of safety critical airborne systems, for proving the correspondence between automatic C source code and its specification expressed with TM Stateflow diagram specification. The process requires a minimum of user intervention in most cases, gives very high confidence and has the potential to shift the traditional technical checks when qualification is effective

On the Determinism of Multi-core Processors

Hard real time systems are evolving in order to respond to the increasing demand in complex functionalities while taking advantage of newer hardware. Software development for safety critical systems has to comply with strict requirements that will facilitate the certification process. During this process, each part of the system is evaluated, requiring a certain level of assurance in order to provide confidence in the product. In particular there must be a level of confidence that the system behaves deterministically that may be based on functionality, resources and time. The success of system verification depends greatly on the capacity to determine its exact behavior. Nonetheless, hardware evolved in order to maximize the average computation power throughput with little to no regard to the deterministic aspect. Therefore modern architectural features of processors, like pipelines, cache memories and co-processors, make it hard to verify that all the needed properties are respected. The multi-core is furthermore difficult to analyze as the architecture employs mechanisms that compromise strong spatial and temporal partitioning when using shared resources without rigorous access control like shared caches or shared input/outputs. In this paper we identify and analyze the main sources of nondeterminism of the multi-cores with regard to the timing estimation. Precise determination of the worst case execution time is a challenging task even in single-core architectures. The problems are accentuated in the multi-core context mainly due to the resource sharing that can lead to highly complex interactions or to nondeterminism. Most of the units that generate behaviors that are hard to take into account can be deactivated, but it is not always easy to predict the impact on the performance. Nevertheless some of the features cannot be disabled (such as the out of order execution or some nondeterministic crossbar access policies) which leads to the invalidation of the respective platform for applications with high criticality level. We will address the problematic units, propose configuration or architecture guidelines and estimate their impact on the performance and determinism of the system

Customization principles of an aeronautics SLM environment and an illustration on aeronautics use cases: the doors management system and the flight control system

International audienceHaving efficient means to build an appropriate system engineering framework is a differentiating factor for the competitiveness of the European aeronautics industry. We present in this paper an approach and a set of concepts enabling the construction and customization of a system engineering environment. These customization principles, set up in the frame of the CESAR project, are driven by a multi-view model-based system development process and by a system data description. The flexibility and the benefits of this approach are demonstrated on two industrial cases: the doors management system and the flight control system

Successfully treated necrotizing fasciitis using extracorporeal life support combined with hemoadsorption device and continuous renal replacement therapy

INTRODUCTION: Necrotizing fasciitis represents a life-threatening infectious condition that causes spreading necrotisis of superficial fascia and subcutaneous cellular tissues. We describe the case of a patient diagnosed with septic and toxic shocks leading to multiple organ failure successfully treated with a combination of extracorporeal life support, continuous renal replacement therapy, and a hemoadsorption device. METHODS: A 41-year-old patient presented with necrotizing fasciitis and multi-organ failure. Initial extracorporeal life support therapy was implanted, compensating for systolic failure. Due to acute renal failure that persisted in time, continuous renal replacement therapy was added. Despite these treatments and as a last attempt to control the septic condition, a CytoSorb hemoadsorption device was installed in parallel to the extracorporeal life support circuit and two sessions were run. RESULTS: During the days following CytoSorb treatment, hemodynamic stabilization was observed, as well as normalization of lactic acidosis and blood parameters. CONCLUSION: This case describes the successful use of CytoSorb with continuous renal replacement therapy and extracorporeal life support in a combined way to overcome a critical phase of septic shock in a young adult patient. This combination of treatments turned out to be efficient for this patient in the context of necrotizing fasciitis

Facteurs de risques psychosociaux de passage à la chronicité des lombalgies, repérables en soins primaires : revue de la littérature

National audienc

Early postoperative undernutrition following aortic valve replacement surgery

Background Experiencing loss of appetite after cardiac surgery is often noted during daily care and has been described by several studies. However, no information is available on either energy needs or spontaneous food intake following aortic valve replacement surgery. The goal of this study was to assess the risk of early postoperative undernutrition following aortic valve replacement in a group of patients who were preoperatively well-nourished. Methods Anthropometrics data (body mass index, fat free mass index, albuminemia and prealbuminemia, extracellular water), energy balance and appetite were assessed in a cross-over prospective observational study. . Each subject was enrolled in two procedures: surgery and routine coronary angiograms which were used for control matched assessment. Data were assessed during the pre-procedure period (d-15 to d-1) and the post-procedure period (d0 to d+4). Energy expenditure was determined by indirect calorimetry. Results 15 patients median aged 73 years old [65–77] were included in the study. In post-surgery period, weight and extracellular water were increased and correlated (r2 = 0.571, p = 0.003). CRP was increased from 2 [2;3] to 91 [73;138] (p = 0.001). Ingested calories decreased from 1451 [1272–1640] kcal to 372 [22–528] kcal (p = 0.001) while energy expenditure was increased from 1358 [1180–1559] kcal to 1613 [1472–1670] kcal (p = 0.002). A severe loss of appetite was noted (p = 0.011). None of these changes were observed in the control phase. Conclusion Energy balance was strongly negative after cardiac surgery. Cardiac surgery increased endogenous metabolism by 20% and a severe loss of appetite decrease food intake by 75%, which does not make it possible to compensate for the increase in resting energy expenditure

Analyse d’interférences mémoires sur les clusters de calcul du pluri-coeurs Kalray MPPA3

The Kalray MPPA3 Coolidge many-core processor is one of the few off-the-shelf high-performance processors amenable to full-fledged static timing analysis. And yet, even on this processor, providing tight execution time upper bounds may prove difficult. In this paper, we consider the sub-problem of bounding the timing overhead due to memory access interferences inside one MPPA3 shared memory compute cluster. This includes interferences between computing cores and interferences between the instruction and data accesses of a given core. We start with a detailed analysis of the MPPA3 compute cluster, with emphasis on three key components: the Prefetch Buffer (PFB), which performs speculative instruction loads, the fixed-priority (FP) arbiter between instruction and data accesses of a core, whose behavior is highly dependent (in the worst case) on interferences from other cores, and the SAP (bursty Round Robin) arbiters guarding access to memory banks. We provide a full-fledged interference analysis covering both levels. This analysis is rooted in a novel modeling of memory access patterns, which describes their worst- case and best-case burstiness, a key factor influencing the MPPA3 arbitration. We evaluate our interference model on multiple applications, ranging from real-life avionics code specified in SCADE to linear algebra code. We also suggests methods for reducing execution time and improving analysis precision by means of code generation.Le pluri-cœurs Kalray MPPA3 Coolidge est un des seuls processeurs haute-performance sur étagère à permettre le calcul de bornes statiques (non-probabilistes) sur le temps d’exécution. Mais même sur ce processeur le calcul de bornes serrées est difficile. Dans cet article, nous traitons le sous-problème du calcul de bornes supérieures sur les interférences dues aux accès concurrents aux bancs de mémoire partagée. De plus, notre analyse se concentre sur un seul cluster de calcul de l’architecture-cible, et s’intéresse seulement aux interférences entre cœurs de calcul du cluster et aux interférences entre accès instruction et données d’un seul cœur. Nous commençons par une analyse détaillée du cluster de calcul MPPA3, mettant l’accent sur trois composants-clefs: le tampon de préchargement anticipé (Prefetch Buffer, ou PFB) qui réalise des préchargements de code spéculatifs, l’arbitre à priorité fixe (FP) entre les accès au code et aux données d’un même cœur de calcul, dont le comportement est dépendant (au pire cas) des interférences d’autres cœurs, et les arbitres SAP (Round Robin avec support pour les rafales) qui contrôlent l’accès aux bancs de mémoire partagée. Nous développons une analyse d’interférences complète par rapport au domaine choisi. Notre analyse est fondée sur une nouvelle modélisation des motifs d’accès à la mémoire, qui permet la représentation du groupage des accès en rafales (dans le pire et dans le meilleur des cas). Ce facteur a une influence très forte sur l’arbitrage MPPA. Nous évaluons notre approche d’analyse d’interférences sur plusieurs applications allant de tâches avioniques appartenant à une application de production spécifiée en SCADE, et jusqu’à du code d’algèbre linéaire représentatif pour les applications de type “jumeau numérique” ou “machine learning”. Nous suggérons aussi des méthodes permettant de réduire le temps d’exécution et d’améliorer la précision de l’analyse par des choix de génération de code

La production scientifique issue de la formation initiale à la faculté de médecine d’Angers entre 2002 et 2008 : de bonne qualité mais insuffisante

IntroductionL’activité de publication scientifique issue de la formation initiale est mal connue. Nous avons évalué la proportion des thèses et des mémoires de spécialité aboutissant à une publication, leur impact en termes de points SIGAPS et les principaux obstacles à la publication de ces travaux. Méthodes Les thèses de doctorat en médecine soutenues de 2002 à 2008 à la faculté de médecine d’Angers ont été recensées à partir du système universitaire de documentation (SUDOC), et les mémoires de spécialité directement auprès des diplômés. Les publications ont été recherchées dans Medline via Pubmed, ISI Web of Knowledge et dans les trois rapports SIGAPS de 2002 à 2008. Une enquête cherchant à connaître les obstacles à la publication a été lancée auprès de tous les directeurs de thèses et responsables de discipline impliqués. Résultats Cinq cent quatre-vingt-dix-huit thèses ont été soutenues, 311 (52 %) en médecine générale et 287 (48 %) en spécialités. Cent soixante-cinq thèses ont donné lieu à publication (28 %) dont 97 (16 %) indexés dans Medline via Pubmed (soit 11 % en médecine générale et 22 % en spécialité). Trente-trois de ces 97 articles (35 %) ont été publiés dans des journaux de haute qualité classés A, B ou C de la classification SIGAPS. Ces articles issus des thèses ont représenté 4,17 % du score SIGAPS du CHU calculé sur un total de 2088 articles au cours de cette période. Deux cent quatre mémoires de spécialités ont donné lieu à 69 articles (33,8 %), dont 50 (24,5 %) indexés dans Medline. Les taux de publication des mémoires de DES et de DESC ont été respectivement de 31 % (45/145) et de 40,7 % (24/59). Ils ont représenté 1,9 % (432 points) du score total SIGAPS. Les principaux obstacles ressentis pour la publication ont été le manque de temps des directeurs, l’éloignement des étudiants après la soutenance et le manque de moyens logistiques. Conclusion La production scientifique issue de la formation initiale à la faculté de médecine d’Angers a été de bonne qualité mais insuffisante quantitativement et peu contributive au financement du CHU malgré un nombre important de diplômés. Un soutien logistique mérite d’être envisagé afin de valoriser la production scientifique issue de la formation initiale