Experimental analysis of the pressure–velocity correlations of external unsteady flow over rocket launchers

Based on simultaneous wall pressure and velocity measurements, the aerodynamic load of a launcher body model is investigated. Two different configurations are considered in order to study the influence of geometrical artifacts on the after body flow and consequently on the aerodynamic load. After a brief presentation of the experimental setup used to get the unsteady wall pressure and external velocity field, a global analysis of the integrated pressure along the nozzle is presented for both configurations. It is shown that the unsteady load induced on a configuration with attachment device involves characteristic frequencies which fits the mechanical response of the structure whereas no particular behavior is observed on the configuration without attachment device. Then, a Proper Orthogonal Decomposition is successively performed from the wall pressure field and from the external velocity field highlighting the relationship between the most energetic structures of the flow and the involved phenomenon. Finally, a pressure/velocity correlation of the POD modes is presented and the most energetic structures of the velocity field are linked to the unsteady load observed on the nozzle. It is then confirmed the structural influence of the attachment device and its contribution to the unsteady loads acting on the nozzle.ESA TRP: "Unsteady Subscale Force Measurements within a Launch Vehicle Base Buffeting Environment"

Evidence for Forcing-Dependent Steady States in a Turbulent Swirling Flow

We study the influence on steady turbulent states of the forcing in a von Karman flow, at constant impeller speed, or at constant torque. We find that the different forcing conditions change the nature of the stability of the steady states and reveal dynamical regimes that bear similarities to low-dimensional systems. We suggest that this forcing dependence may be applicable to other turbulent systems

European Arctic Initiatives Compendium

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Treatment-resistant ophthalmoplegia in Myasthenia gravis: extraocular muscle pathology, the role of TGFβ1 and the derivation of induced pluripotency towards 'disease-in-a-dish' modeling

Myasthenia gravis (MG) is an autoimmune disease in which pathogenic antibodies target specific neuromuscular junction proteins, most frequently acetylcholine receptors (AChR). Among those without detectable AChR-antibodies, a subgroup of patients has antibodies directed against muscle-specific tyrosine kinase (MuSK). In MG the pathogenic antibodies result in failure of neuromuscular transmission with consequent fatiguable skeletal muscle weakness. MG frequently affects the extraocular muscles (EOMs) early in the course of the disease, resulting in diplopia and ptosis, which is usually reversible with treatment. A treatment-resistant ophthalmoplegia and ptosis occurs as a complication of MG in a distinct subset of cases referred to as OP-MG. The EOMs are highly specialised muscle tissue with a unique physiological and immunological microenvironment with a large satellite cell niche, a distinct muscle fibroblast population, different transcriptional and cellular signaling pathways and fewer intrinsic complement regulatory proteins to protect them against antibody- activated complement-mediated damage. We hypothesised that in OP-MG, there is a differential response of the EOMs to the underlying MG disease process(es) on a genetic and molecular level, resulting in abnormal myofibre homeostasis. We aimed to report descriptive clinical-pathological data pertaining to EOM function and histopathological and ultrastructural EOM tissue analysis of a patient with OP- MG versus that of a non-MG control (both consented to EOM donation at ocular realignment surgery). EOM tissue from an OP-MG individual with AChR- and MuSK- antibody negative MG, demonstrated predominantly myopathic pathology and ultrastructural evidence of mitochondrial stress. The OP-MG EOM findings differ from the control EOM, which showed normal muscle histopathology in a patient undergoing strabismus surgery for a sensory exotropia in a non-seeing eye (loss of retinal stimulus for fusion) and a similar duration of deviation. These OP-MG findings appear to better correlate with previously reported histology/ultrastructure in limb muscle in MuSK-positive MG rather than AChR-positive MG. We next focussed on transforming growth factor beta-1 (TGFβ1) as a critical cytokine involved in muscle repair. An auto-induction pathway in muscle allows TGFβ1 expression to influence the transdifferentiation of satellite cells into myofibroblasts or myoblasts. In orbital fibroblasts, TGFβ1 has also been shown to upregulate decay accelerating factor (DAF), a complement regulatory protein expressed at lower levels in EOMs than other muscles, which should protect against complement-mediated injury. We established OP-MG and control-MG phenotype-specific dermal fibroblast cell lines and performed immunoblotting to evaluate TGFβ1-induced Smad3 phosphorylation and Daf expression in mouse myotubes. We demonstrated repression of phosphorylated-Smad3, a marker of the canonical TGFβ1 pathway, in OP-MG versus control MG fibroblasts after treatment with TGFβ1. We also demonstrated that TGFβ1 significantly upregulates Daf expression levels in mouse myoblasts. Taken together, these results suggest that OP-MG fibroblasts (and possibly myofibroblasts) are likely to be more susceptible to complement-mediated damage and abnormal myofibrogenesis due to their altered response to TGFβ1 stimulation and secondary DAF upregulation. Finally we investigated the feasability of establishing an in vitro disease model for MG or OP-MG by reprogramming dermal fibroblasts into disease phenotype-specific induced pluripotent stem (iPS) cells. We successfully generated and characterised iPS cells for one individual. However, this process was very labour-intensive, cost-inefficient and time-consuming, taking approximately four months to establish pluripotency in a single patient and thereby limited its further application(s). In conclusion, the EOM ultrastructural findings of an OP-MG case are novel and show similar findings to those described in limb skeletal muscle of MuSK-positive MG patients. The TGFβ1 pathway appears to be differentially regulated in OP-MG compared to control-MG cases and this may impact DAF upregulation in the EOMs in MG patients. Finally, our group is exploring an alternative method of establishing a 'disease-in-a-dish' model that is more cost-effective and practically feasible than the iPS cell route

Thermal Effects in a Two-Dimensional Hybrid Elastic Structure

AbstractIn this paper we consider a two-dimensional hybrid thermo-elastic structure consisting of a thermo-elastic plate which has a beam attached to its free end. We show that the initial-boundary-value problem for the interactive system of partial differential equations which take account of the mechanical strains/stresses and the thermal stresses in the plate and the beam, can be associated with a uniformly bounded evolution operator. It turns out that the interplay of parabolic dynamics due to the thermal effects in the hybrid structure and the hyperbolic dynamics associated with the elasticity of the structure yields analyticity for the entire system. This result yields solvability for the problem under optimal initial freedom of the displacement, velocity, and temperature in the plate and the beam, while uniform stability is readily available

Urvillers – Zac de l’Épinette, « Les Terres Noires »

La prescription de fouille est consécutive au résultat positif d’un diagnostic réalisé en juillet 2008. Cette opération intègre le programme de fouille préventive menée depuis 2002 dans le cadre de l’aménagement de la Zac de l’Épinette. Sur les 10 ha diagnostiqués, deux petits secteurs concentrant des vestiges protohistoriques et antiques ont été prescrits afin d’identifier la nature et la forme de ces établissements. Fig. 1 – Plan général DAO : V. Marié (Inrap). Site I : un établissement en..

How school ecologies facilitate resilience among adolescents with Intellectual Disability: Guidelines for teachers

The global prioritisation of the inclusion of learners with disabilities, and of vulnerable young people’s resilience, means that teachers worldwide require insight into how best to facilitate the resilience of adolescents made vulnerable by intellectual disability (ID). To provide such insight, we conducted a secondary data analysis of a multiple case study of resilient adolescents with ID attending special schools in Gauteng Province, South Africa. The visual and narrative data that inform this case study were generated by resilient adolescents with ID (n = 24), and their teachers (n = 18). Four school-related themes emerge from their accounts of resilience-supporting factors associated with their schools for the physically and severely intellectually disabled (SPSID). From these, we distill three uncomplicated actions mainstream school ecologies can execute in order to enable the resilience of included adolescents with ID. Their simplicity and ordinariness potentiate universally useful ways for mainstream teachers to champion the resilience of included adolescents with ID.Keywords: adolescents; formal services; health and well-being; inclusion; intellectual disability; qualitative research; resilience; SPSID; teacher

Wake behind contaminated bubbles in a solid-body rotating flow

International audienc

Un modèle stochastique pour l'écoulement de von Kármán

URL: http://www-spht.cea.fr/articles/S03/015 , Paris, France, 13-14 mars 2003National audienceUn système d'équations stochastiques nous sert à décrire l'évolution de la vitesse de rotation d'un disque ainsi que le couple appliqué dans l'écoulement de Von-Karman. Ce dernier est étudié de façon analytique pour deux modes de forçage: vitesse angulaire ou couple constant. Le principal résultat est que l'on retrouve la relation expérimentale de Titon et Cadot : dans la limite de l'inertie du disque nulle, la puissance injecté dans la turbulence fluctue deux fois moins lorsque l'on force à couple constant comparé au forçage à vitesse angulaire constante. Ensuite, les distributions de probabilité de la vitesse angulaire et du couple sont comparées à des données expérimentales