Détermination d'une loi de propagation de fissure de fatigue par corrélation d'images numériques

La Corrélation d'Images Numériques (CIN) a été utilisée pour identifier des lois de propagation de fissures en utilisant comme cadre les séries de Williams. La procédure d'identification est menée en trois étapes : (i) détermination des champs de déplacement sur chaque cycle de chargement considéré; (ii) détermination des termes des séries de Williams par une minimisation de la différence des champs expérimentaux avec les solutions analytiques de Williams paramétrées automatiquement; (iii) les coefficients identifiés sont alors utilisés pour initialiser la troisième étape qui est une corrélation d'images dite « intégrée » où les fonctions de forme sont les séries de Williams. Cette procédure permet d'obtenir des résultats plus précis que par une simple méthode projective et permet de gagner un temps précieux en initialisant les termes des séries de Williams pour la corrélation intégrée

Development of Single- and Double-sided Ladders for the ILD Vertex Detectors

We discuss two projects exploring the integration of thin CMOS pixel sensors in order to prototype ladders matching the geometry needed for the ILD vertex detector. The PLUME project has designed and fabricated full-size and fully functional double- sided layers which currently reach 0.6 % X0 and aim for 0.3 % X0 in mid-2012. Another approach, SERNWIETE, consists in wrapping the sensors in a polyimide-based micro-cable to obtain a supportless single-sided ladder with a material budget around 0.15 % X0. First promising samples have been produced and the full-size prototype is expected in spring 2012.Comment: International Workshop on Future Linear Colliders, LCWS 2011, Granada, Spain, 2011, 26-30 Septembe

The observed link between urbanization and invasion can depend on how invasion is measured

Aim Cities are thought to promote biological invasions because invasive species are more often introduced in urban areas and because they are more successful in disturbed environments. However, the association is not as strongly supported by the literature as is generally assumed and might depend on how urbanization and invasion are measured. In this study, we test if the type of data used to assess the link between urbanization and invasion can affect a study's conclusions. Location Europe and middle Rhône valley (~5000 km2 in south-eastern France). Method We studied the spatial distribution of the invasive garden ant Lasius neglectus in its current introduced range in Europe and tested its association with urbanization using three measures of invasion (presence-only, presence–absence and population area) and two measures of urbanization (urban/nonurban land cover classification and proportion of impervious surfaces (buildings, road) per spatial unit). Results Based on presence-only data across Europe, L. neglectus occurred in urban areas 10 times more often than expected from a random geographical distribution. However, when controlling for spatial bias in sampling effort with presence–absence data (1870 sampling locations in the middle Rhône valley, France), the occurrence of the species was independent of urbanization. Moreover, the surface occupied by L. neglectus populations was negatively correlated with urbanization. Main conclusions These findings show that the type of occurrence data used to test the link between urbanization and invasion can strongly affect the conclusion of a study. This is particularly concerning because invasion studies often use presence-only data that are likely biased towards cities. Future urban invasions studies must be carefully designed to avoid this pitfall.Peer reviewe

A Kappa model for hepatic stellate cells activation by TGFB1

International audienc

Lean techniques application towards efficient collaborative robot integration: an experimental study

Paper aims : Highlight the practical implications of coupling collaborative robots with lean manufacturing techniques and understand mutual contributions towards enhanced operational performance. Originality : Usage of an experimental approach, focusing on lean techniques as a differentiating skill to implement efficiently collaborative robots in a production representative environment. Research method : Experimental case study, based on the gradual implementation of a collaborative robot within a manual assembly process in order to design a collaborative process. Main findings : Guidelines for transition from manual to collaborative process, incorporating incremental improvement loops – and related skills – enabling enhanced performance. Implications for theory and practice : Identification of a set of lean techniques contributing positively to collaborative robots’ usage, incorporated in a step by step operator driven implementation process

A Kappa model for hepatic stellate cells activation by TGFB1

International audienceAll chronic hepatitis are associated with the development of fibrosis, which results in abnormal deposition of the extracellular matrix (ECM) leading to severe liver dysfunction. Fibrosis final stage, called cirrhosis, is the main risk of development of hepatocellular carcinoma (HCC). At the cellular level, hepatic stellate cells (HSCs) are major actors of fibrosis and tumor progression. Upon liver injury, HSCs are activated to repair tissue and are subsequently eliminated through three mechanisms: apoptosis, senescence and reversion, leading to a return to healthy status [5]. However,when the injury persists, HSCs remain activated with a myobroblastic phenotype, and extracellular matrix accumulates, leading to fibrosis, cirrhosis and cancer. Understanding the dynamics of HSC activation and their regulation by TGFB1 is essential to identify markers and therapeutic targets that may favor the resolution of fibrosis at the expense of its progression. For this purpose, we are developing a modelling approach using the Kappa language. Kappa is a rule-based language used for the rewriting of site graphs [1, 2, 4, 3] aiming at describing networks of interactions between occurrences of components, using a syntax inspired by chemistry. In this model, the components are occurrences of HSC in different states, and occurrences of the TGFB1 protein. Our preliminary results suggest a high plasticity of the HSC response to TGFB1 stimulation. Future work will focus on the integration of the ECM component networks that regulate TGFB1 availability.References:[1] O. Andrei and H. Kirchner. A rewriting calculus for multigraphs with ports. Electr. NotesTheor. Comput. Sci., 219:67–82, 2008.[2] V. Danos and C. Laneve. Formal molecular biology. Theoretical Computer Science,325(1):69 – 110, 2004. Computational Systems Biology.[3] A. Ehrlich, D. Duche, G. Ouedraogo, and Y. Nahmias. Challenges and opportunitiesin the design of liver-on-chip microdevices. Annual Review of Biomedical Engineering,21(1):219–239, 2019. PMID: 31167098.[4] J. R. Faeder, M. L. Blinov, B. Goldstein, and W. S. Hlavacek. Rule-based modeling ofbiochemical networks. Complexity, 10(4):22–41, 2005.[5] T. Kisseleva and D. Brenner. Molecular and cellular mechanisms of liver fibrosis and itsregression. Nature Reviews Gastroenterology & Hepatology, pages 1–16, 2020

A Kappa model for hepatic stellate cells activation by TGFB1

International audienc

Using a direct simulation Monte Carlo approach to model collisions in a buffer gas cell

A direct simulation Monte Carlo (DSMC) method is applied to model collisions between He buffer gas atoms and ammonia molecules within a buffer gas cell. State-tostate cross sections, calculated as a function of collision energy, enable the inelastic collisions between He and NH3 to be considered explicitly. The inclusion of rotationalstate-changing collisions affects the translational temperature of the beam, indicating that elastic and inelastic processes should not be considered in isolation. The properties of the cold molecular beam exiting the cell are examined as a function of the cell parameters and operating conditions; the rotational and translational energy distributions and are in accord with experimental measurements. The DSMC calculations show that thermalisation occurs well within the typical 10-20 mm length of many buffer gas cells, suggesting that shorter cells could be employed in many instances – yielding a higher flux of cold molecules