Model of the leaky bucket ATM generic flow control mechanism: a case study on solving large cyclic models

The authors describe and solve a Markov model of the leaky bucket ATM generic flow control mechanism. The model has a space cardinality which grows quickly with its parameters and is challenging to solve. Exploiting the cyclic nature of the model, the authors develop a methodology which allows them to efficiently solve instances of the model with 3,905,134 states and 53,869,532 transitions using 29.8 Mbytes of memory and 222 Mbytes of disc storage. The CPU utilisation is high (between 70% and 90%). The methodology is new and can be easily extended to any kind of finite cyclic Markov models.Postprint (published version

A Bayesian framework to objectively combine metrics when developing stressor specific multimetric indicator

In the context of the European Water Framework Directive (WFD), monitoring programs and related indicators have been developed to assess anthropogenic impacts on various components of aquatic ecosystems. While great precautions are usually taken when selecting and calculating relevant core metrics, little attention is generally paid to the generation of the multimetric indicator, i.e. the combination of the different core metrics. Indeed, most multimetric indicators are generated by simply averaging or summing metrics, without taking into account their sensitivity and their variability. Moreover, few indicators provide a rigorous estimate of the uncertainty of the assessments, while this estimation is essential for managers. In this context, we developed a Bayesian framework to build multimetric indicators aiming at improving those two weaknesses. This framework is based on two phases. First, pressure-impact statistical models are developed to quantify the impact of pressure on various fish metrics. Then the Bayesian theorem is applied to estimate probabilities of being at a certain anthropogenic pressure level from fish observation and pressure-impact models outputs. The Bayesian theorem allows to combine objectively the different core metrics, taking into account their sensitivity and their variability, and to provide rigorous uncertainty quantification, which is especially valuable in the WFD context. The method is applied as illustrative example on transitional French water bodies to demonstrate its relevance, especially in the Water Framework Directive context though the method is generic enough to be applied in various contexts

Plans d'expériences optimaux et régression PLS pour l’analyse de sensibilité globale

National audienc

Plans d'expériences optimaux et régression PLS pour l’analyse de sensibilité globale

National audienc

Model of the leaky bucket ATM generic flow control mechanism: a case study on solving large cyclic models

The authors describe and solve a Markov model of the leaky bucket ATM generic flow control mechanism. The model has a space cardinality which grows quickly with its parameters and is challenging to solve. Exploiting the cyclic nature of the model, the authors develop a methodology which allows them to efficiently solve instances of the model with 3,905,134 states and 53,869,532 transitions using 29.8 Mbytes of memory and 222 Mbytes of disc storage. The CPU utilisation is high (between 70% and 90%). The methodology is new and can be easily extended to any kind of finite cyclic Markov models

Syndrome d'activation macrophagique associé à une granulomatose et une infiltration lymphocytaire T CD4 diffuse révélant une nocardiose disséminée et une infection pulmonaire à Streptomyces spp

International audienceRésumé Introduction Le syndrome d'activation lympho-histiocytaire (SALH) est un syndrome rare, souvent secondaire à des pathologies infectieuses, notamment chez les immunodéprimés. Nous décrivons ici un cas rare de SALH secondaire à une nocardiose disséminée et une infection pulmonaire à Streptomyces spp. Observation Une femme de 69 ans notait l'apparition progressive de nodules sous-cutanés des avant-bras et des lombes, associée à une neuropathie périphérique et un nodule pulmonaire du lobe supérieur droit. La biopsie cutanée retrouvait un granulome. Les lésions cutanées s'aggravaient et la patiente présentait un SALH avec probable atteinte cardiaque et neurologique, associé à une granulomatose cutanée et une prolifération lymphocytaire polyclonale diffuse. La PCR spécifique Nocardia était positive sur la biopsie cutanée et les prélèvements respiratoires revenaient positifs à Streptomyces spp en culture et Nocardia en PCR. L'évolution sous traitement antibiotique était favorable. Conclusion La découverte d'un SALH doit toujours faire rechercher une étiologie infectieuse. Devant l'absence d'étiologie évidente d'un SALH, l'hypothèse d'une infection à germe à croissance exigeante tels que Nocardia ou Streptomyces doit être évoquée. Introduction Hemophagocytic lymphohistiocytosis (HLH) is a rare syndrome frequently secondary to infectious disease, especially in immuno-compromised patients. We report a HLH secondary to disseminated nocardiosis and Streptomyces spp pulmonary infection. Case report A 69-years-old women had recent subcutaneous nodules of the forearms and loins associated with peripheral neuropathy and pulmonary nodule of the right upper lobe. Cutaneous biopsy revealed granuloma. Cutaneous lesions worsened and the patient developed a HLH with probable cardiac and neurological involvement, associated with cutaneous granulomatosis and diffuse polyclonal lymphocyte proliferation. Nocardia PCR was positive in cutaneous biopsy. Pulmonary samples revealed Streptomyces in culture and Nocardia in PCR. The evolution under antibiotic treatment was favorable. Conclusion Recent diagnosis of HLH without obvious etiology should lead to etiological investigation, including the search for infections with slow-growing bacteria such as Nocardia or Streptomyces spp