Modelling crisis management for improved action and preparedness (CRISMA): Modelling submersion on the Charente-Maritime coast

International audienceCRISMA is a Research and Development project financed by the European Community. Its objective is to develop a simulation-based decision support system, in different domains of the natural or industrial risk (flood, snowstorm, seism, forest fires, accidental pollution, urban accidents). The application in France, coordinated by ARTELIA Eau & Environnement, is devoted to the submersion risk on the Charente-Maritime coast and based on the experience feedback of the storm Xynthia in February, 2010. In this framework, a specific work is in progress through a thesis realized in collaboration between ARTELIA and lNRIA. Its objective is to elaborate a methodology of multi-model coupling which should be effective and applicable for the CRISMA project. These models may differ in several ways, related either to the physics and/or to the numeric concepts. The developed methodology may allow to taking into account more specific areas (urban zone, bridge in charge, …), but also should be able to simplify the simulation by dimension changes of model parts (for example, a 1D model for rivers, and a 2D one for sea). The present work addresses more specifically the problem of coupling models with different spatial dimensions

Coupling 3D Navier-Stokes and 1D shallow water models

International audienceThe present work addresses the problem of coupling hydrodynamical models with different spatial dimensions, which can be used in order to reduce the computational cost of river numerical models. We show that this problem can be tackled quite efficiently by designing a simple algorithm using techniques borrowed from domain decomposition theory. This algorithm is non intrusive, i.e. allows using existing numerical models with very few modifications. The method is illustrated on an academic test-case, namely a free surface flow in a bend-shaped channel. A 3-D Navier-Stokes model is coupled with a 1-D shallow water model, and results are compared to those obtained in a fully 3-D case. It is shown that the coupling algorithm provides an accurate solution, which can be improved thanks to an iterative algorithm (Schwarz method). This study is performed using the Mascaret-Telemac system

Coupling 3D Navier-Stokes and 1D shallow water models

International audienceThe present work addresses the problem of coupling hydrodynamical models with different spatial dimensions, which can be used in order to reduce the computational cost of river numerical models. We show that this problem can be tackled quite efficiently by designing a simple algorithm using techniques borrowed from domain decomposition theory. This algorithm is non intrusive, i.e. allows using existing numerical models with very few modifications. The method is illustrated on an academic test-case, namely a free surface flow in a bend-shaped channel. A 3-D Navier-Stokes model is coupled with a 1-D shallow water model, and results are compared to those obtained in a fully 3-D case. It is shown that the coupling algorithm provides an accurate solution, which can be improved thanks to an iterative algorithm (Schwarz method). This study is performed using the Mascaret-Telemac system

Human resources for primary health care in sub-Saharan Africa: progress or stagnation?

BACKGROUND: The World Health Organization defines a "critical shortage" of health workers as being fewer than 2.28 health workers per 1000 population and failing to attain 80% coverage for deliveries by skilled birth attendants. We aimed to quantify the number of health workers in five African countries and the proportion of these currently working in primary health care facilities, to compare this to estimates of numbers needed and to assess how the situation has changed in recent years. METHODS: This study is a review of published and unpublished "grey" literature on human resources for health in five disparate countries: Mali, Sudan, Uganda, Botswana and South Africa. RESULTS: Health worker density has increased steadily since 2000 in South Africa and Botswana which already meet WHO targets but has not significantly increased since 2004 in Sudan, Mali and Uganda which have a critical shortage of health workers. In all five countries, a minority of doctors, nurses and midwives are working in primary health care, and shortages of qualified staff are greatest in rural areas. In Uganda, shortages are greater in primary health care settings than at higher levels. In Mali, few community health centres have a midwife or a doctor. Even South Africa has a shortage of doctors in primary health care in poorer districts. Although most countries recognize village health workers, traditional healers and traditional birth attendants, there are insufficient data on their numbers. CONCLUSION: There is an "inverse primary health care law" in the countries studied: staffing is inversely related to poverty and level of need, and health worker density is not increasing in the lowest income countries. Unless there is money to recruit and retain staff in these areas, training programmes will not improve health worker density because the trained staff will simply leave to work elsewhere. Information systems need to be improved in a way that informs policy on the health workforce. It may be possible to use existing resources more cost-effectively by involving skilled staff to supervise and support lower level health care workers who currently provide the front line of primary health care in most of Africa

Rotavirus-Like Particles: A Novel Nanocarrier for the Gut

The delivery of bioactive molecules directly to damaged tissues represents a technological challenge. We propose here a new system based on virus-like particles (VLP) from rotavirus, with a marked tropism for the gut to deliver bio-active molecules to intestinal cells. For this, nonreplicative VLP nanoparticles were constructed using a baculovirus expression system and used to deliver an exogenous biomolecule, the green fluorescent protein (GFP), into either MA104 cells or intestinal cells from healthy and 2,4,6-trinitrobenzene sulfonic acid (TNBS)-treated mice. Our results show that expression of rotavirus capsid proteins in baculovirus led to the auto assembly of VLP that display similar properties to rotavirus. In vitro experiments showed that VLP were able to enter into MA104 cells and deliver the reporter protein. Intragastric administration of fluorescent VLP in healthy and TNBS-treated mice resulted in the detection of GFP and viral proteins in intestinal samples. Our results demonstrate an efficient entry of non-replicative rotavirus VLP into the epithelial cell line MA104 and provide the first in vivo evidence of the potential of these nanoparticles as a promising safe candidate for drug delivery to intestinal cells

A new Python3 module for TELEMAC-MASCARET dedicated to post-treatment: Postel

Hydrodynamic

A comparative study of some properties of cassava and tree cassava starch films

Cassava and tree cassava starch films plasticized with glycerol were produced by casting method. Different glycerol contents (30, 35, 40 and 45 wt. % on starch dry basis) were used and the resulting films were fully characterized. Their water barrier and mechanical properties were compared. While increasing glycerol concentration, moisture content, water solubility, water vapour permeability, tensile strength, percent elongation at break and Young's modulus decreased for both cassava and tree cassava films. Tree cassava films presented better values of water vapour permeability, water solubility and percent elongation at break compared to those of cassava films, regardless of the glycerol content

Staphylococcus aureus RNAIII Binds to Two Distant Regions of coa mRNA to Arrest Translation and Promote mRNA Degradation

Staphylococcus aureus RNAIII is the intracellular effector of the quorum sensing system that temporally controls a large number of virulence factors including exoproteins and cell-wall-associated proteins. Staphylocoagulase is one major virulence factor, which promotes clotting of human plasma. Like the major cell surface protein A, the expression of staphylocoagulase is strongly repressed by the quorum sensing system at the post-exponential growth phase. Here we used a combination of approaches in vivo and in vitro to analyze the mechanism used by RNAIII to regulate the expression of staphylocoagulase. Our data show that RNAIII represses the synthesis of the protein through a direct binding with the mRNA. Structure mapping shows that two distant regions of RNAIII interact with coa mRNA and that the mRNA harbors a conserved signature as found in other RNAIII-target mRNAs. The resulting complex is composed of an imperfect duplex masking the Shine-Dalgarno sequence of coa mRNA and of a loop-loop interaction occurring downstream in the coding region. The imperfect duplex is sufficient to prevent the formation of the ribosomal initiation complex and to repress the expression of a reporter gene in vivo. In addition, the double-strand-specific endoribonuclease III cleaves the two regions of the mRNA bound to RNAIII that may contribute to the degradation of the repressed mRNA. This study validates another direct target of RNAIII that plays a role in virulence. It also illustrates the diversity of RNAIII-mRNA topologies and how these multiple RNAIII-mRNA interactions would mediate virulence regulation

A Putative P-Type ATPase Required for Virulence and Resistance to Haem Toxicity in Listeria monocytogenes

Regulation of iron homeostasis in many pathogens is principally mediated by the ferric uptake regulator, Fur. Since acquisition of iron from the host is essential for the intracellular pathogen Listeria monocytogenes, we predicted the existence of Fur-regulated systems that support infection. We examined the contribution of nine Fur-regulated loci to the pathogenicity of L. monocytogenes in a murine model of infection. While mutating the majority of the genes failed to affect virulence, three mutants exhibited a significantly compromised virulence potential. Most striking was the role of the membrane protein we designate FrvA (Fur regulated virulence factor A; encoded by frvA [lmo0641]), which is absolutely required for the systemic phase of infection in mice and also for virulence in an alternative infection model, the Wax Moth Galleria mellonella. Further analysis of the ΔfrvA mutant revealed poor growth in iron deficient media and inhibition of growth by micromolar concentrations of haem or haemoglobin, a phenotype which may contribute to the attenuated growth of this mutant during infection. Uptake studies indicated that the ΔfrvA mutant is unaffected in the uptake of ferric citrate but demonstrates a significant increase in uptake of haem and haemin. The data suggest a potential role for FrvA as a haem exporter that functions, at least in part, to protect the cell against the potential toxicity of free haem