Model Based Risk Assessment of Procedures and Systems for Aircraft Trajectory Management

International audienceModern Air Traffic Management (ATM) concepts of operation require a strong interaction between agents such as human operators (pilots, air traffic controllers) and information technology systems (either on-ground or on-board). Although risks shall jointly be managed by all these agents, current risk assessment techniques are usually dedicated to only one class ofagents (either human operators or IT systems). This paper addresses this issue. It proposes to extend Model Based Safety Assessment (MBSA) techniques originally developed to assess complex systems. This MBSA extension enables to assess how risk can be jointly managed by procedures and systems. The paper shows the methodology used and it presents lessons learnt from an aircraft trajectory management case study

CT pelvimetry of variant pelvis and child birth prognosis

The aim of this study was to determine the threshold values of pelvimetry by scanning and to evaluate the ability of the pelvimetry alone to diagnose a fetal-pelvic disproportion. It was an observational retrospective study on 410 pregnant women who had a scanner pelvimetry for any reasons. Based on the fetal presentations, two subgroups (breech and cephalic -others) have been defined. Measurements of the main obstetric diameters (promonto-retropubic, median transverse and dual sciatica) were taken. The 5th and 10th percentile were calculated as well as the 90th and 95th to determine the threshold values of pelvimetry by scanner. The scanner values found on CT were compared with the standard X ray pelvimetry values. Referring to extreme values obtained by pelvimetry scanner, some pathological pelvic brim were reconstructed in 3D. Moreover, the delivery prognostic was analyzed by crossing the pelvic inlet dimensions (Magnin index) and pelvic outlet dimensions (bi-sciatic diameter) with the outcome of the delivery. The mean values of the scanno-pelvimetry measurement in our series were:m12,39 cm (± 1) for the promonto-retropubic diameter, 12.88 cm (± 1.01) for the transverse median diameter and 11 cm (± 1.32) for the bi-sciatic diameter. These measurements provided an accuracy less than 1 cm compared to the standard ray pelvimetry. Although Magnin index at 23 allows a vaginal delivery, 51% of oursample have failed. Moreover, for the Magnin index at 24 and 25, the vaginal delivery failure rate remains high:45.1% and 39.61% respectively. Compared to classical pelvimetry, pelvimetry by scanner provides additional precision and allows to study the geometry of the basin. However, the pelvimetry alone could not be effective to establish the prognosis of vaginal delivery.Keywords: scanno-pelvimetry, prognosis, deliver

The sialic acid binding activity of the S protein facilitates infection by porcine transmissible gastroenteritis coronavirus

<p>Abstract</p> <p>Background</p> <p>Transmissible gastroenteritis virus (TGEV) has a sialic acid binding activity that is believed to be important for enteropathogenicity, but that has so far appeared to be dispensable for infection of cultured cells. The aims of this study were to determine the effect of sialic acid binding for the infection of cultured cells under unfavorable conditions, and comparison of TGEV strains and mutants, as well as the avian coronavirus IBV concerning their dependence on the sialic acid binding activity.</p> <p>Methods</p> <p>The infectivity of different viruses was analyzed by a plaque assay after adsorption times of 5, 20, and 60 min. Prior to infection, cultured cells were either treated with neuraminidase to deplete sialic acids from the cell surface, or mock-treated. In a second approach, pre-treatment of the virus with porcine intestinal mucin was performed, followed by the plaque assay after a 5 min adsorption time. A student's t-test was used to verify the significance of the results.</p> <p>Results</p> <p>Desialylation of cells only had a minor effect on the infection by TGEV strain Purdue 46 when an adsorption period of 60 min was allowed for initiation of infection. However, when the adsorption time was reduced to 5 min the infectivity on desialylated cells decreased by more than 60%. A TGEV PUR46 mutant (HAD3) deficient in sialic acid binding showed a 77% lower titer than the parental virus after a 5 min adsorption time. After an adsorption time of 60 min the titer of HAD3 was 58% lower than that of TGEV PUR46. Another TGEV strain, TGEV Miller, and IBV Beaudette showed a reduction in infectivity after neuraminidase treatment of the cultured cells irrespective of the virion adsorption time.</p> <p>Conclusions</p> <p>Our results suggest that the sialic acid binding activity facilitates the infection by TGEV under unfavorable environmental conditions. The dependence on the sialic acid binding activity for an efficient infection differs in the analyzed TGEV strains.</p

Vers un système de mesure des flux aériens de microorganismes

Si une bonne partie des microorganismes présents dans l'atmosphère provient des surfaces terrestres, seules quelques rares tentatives de mesure de leur flux d'émission ont été effectuées; on ignore ainsi presque tout des quantités de microorganismes échangées entre surface et atmosphère, et a fortiori des mécanismes responsables de ces flux. Ce manque est dû à la difficulté de l'entreprise : (i) aucun capteur rapide de concentration n'existant pour ce type d'aérosols, la méthode de référence, celle des « covariances turbulentes >>, ne peut être utilisée ; (ii) la méthode « du gradient >>, où l'on estime le flux à partir de la différence de concentration moyenne entre deux altitudes, n'est applicable que sur des sites >. Une alternative potentielle réside dans la méthode REA, ou « relaxed-eddy accumulation », précédemment développée pour des espèces dont seules des mesures lentes de concentration sont possibles ; elle consiste à mesurer une différence de concentration moyenne entre deux échantillons d'air prélevés pendant des périodes où la vitesse verticale de l'air est soit positive (mouvement ascendant),soit négative (descendant). Nous étudions ici la possibilité d'adapter cette méthode à la mesure du flux d'émission bactérienne au-dessus de surfaces végétales. Après une présentation de son principe et de ses conditions d'utilisation, nous décrivons un prototype de système en cours de développement. Ce dernier a été testé et amélioré lors de quatre campagnes de mesures au champ pendant lesquelles plusieurs capteurs de particules ont été évalués (impacteurs réels et virtuels, filtres). Les résultats obtenus sont encourageants et leur analyse permet de proposer des voies d'amélioration du systèm

Comment adapter les échelles de phénologie aux champignons phytopathogènes, et pour quelles utilisations ?

National audienceAucune échelle globale de notation de la phénologie des champignons phytopathogènes sensu lato n’existe à notre connaissance. Pourtant, un tel outil permettrait d’étudier et de comprendre les impacts du changement climatique et de l’évolution des pratiques sur la santé des plantes. Une première version générique de cette échelle a été construite en identifiant des stades de vie communs aux différents règnes et divisions (stade principal et secondaire) et spécifique de chaque division considérée (stade tertiaire). Toutefois l'utilisation de cette échelle reste inféodée à l’observation de signes et de symptômes sur la plante hôte, ce qui nous a conduit à développer en parallèle un lexique associé à une banque d’images. Nous testons actuellement la pertinence et la généricité de cette échelle sur différents agents pathogènes des cultures (annuelles et pérennes), dont les cycles biologiques sont particulièrement contrastés

Patient-derived glioblastoma stem cells transfer mitochondria through tunneling nanotubes in tumor organoids

International audienceGlioblastoma (GBM) is the most aggressive brain cancer and its relapse after surgery, chemo and radiotherapy appears to be led by GBM stem cells (GSCs). Also, tumor networking and intercellular communication play a major role in driving GBM therapy-resistance. Tunneling Nanotubes (TNTs), thin membranous open-ended channels connecting distant cells, have been observed in several types of cancer, where they emerge to drive a more malignant phenotype. Here, we investigated whether GBM cells are capable to intercommunicate by TNTs. Two GBM stem-like cells (GSLCs) were obtained from the external and infiltrative zone of one GBM from one patient. We show, for the first time, that both GSLCs, grown in classical 2D culture and in 3D-tumor organoids, formed functional TNTs which allowed mitochondria transfer. In the organoid model, recapitulative of several tumor's features, we observed the formation of a network between cells constituted of both Tumor Microtubes (TMs), previously observed in vivo, and TNTs. In addition, the two GSLCs exhibited different responses to irradiation in terms of TNT induction and mitochondria transfer, although the correlation with the disease progression and therapy-resistance needs to be further addressed. Thus, TNT-based communication is active in different GSLCs derived from the external tumoral areas associated to GBM relapse, and we propose that they participate together with TMs in tumor networking