Rheological Model for Wood

Wood as the most important natural and renewable building material plays an important role in the construction sector. Nevertheless, its hygroscopic character basically affects all related mechanical properties leading to degradation of material stiffness and strength over the service life. Accordingly, to attain reliable design of the timber structures, the influence of moisture evolution and the role of time- and moisture-dependent behaviors have to be taken into account. For this purpose, in the current study a 3D orthotropic elasto-plastic, visco-elastic, mechano-sorptive constitutive model for wood, with all material constants being defined as a function of moisture content, is presented. The corresponding numerical integration approach, with additive decomposition of the total strain is developed and implemented within the framework of the finite element method (FEM). Moreover to preserve a quadratic rate of asymptotic convergence the consistent tangent operator for the whole model is derived. Functionality and capability of the presented material model are evaluated by performing several numerical verification simulations of wood components under different combinations of mechanical loading and moisture variation. Additionally, the flexibility and universality of the introduced model to predict the mechanical behavior of different species are demonstrated by the analysis of a hybrid wood element. Furthermore, the proposed numerical approach is validated by comparisons of computational evaluations with experimental results.Comment: 37 pages, 13 figures, 10 table

Acute Tubulo-interstitial Nephritis with Positive Anti-Neutrophil Cytoplasmic Antibodies

Introduction: Anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis involving the kidney usually comprises pauci-immune, necrotizing glomerulonephritis with crescents. Mononuclear tubulo-interstitial infiltrates are common in ANCA associated vasculitis, but these have usually been described in conjunction with glomerulitis. Acute tubulo-interstitial nephritis (ATIN) is a common cause of acute kidney injury that is most frequently induced by drugs or infections. Idiopathic ATIN has rarely been reported in association with the presence of a positive ANCA. These two entities seem to share a common immunological basis.Case report: We report a 75 years-old male patient who presented with acute kidney injury and his serum tested positive for p-ANCA by indirect immunofluoresence with a titer of 1/320. Testing by ELISA demonstrated anti-myeloperoxidase (MPO) specificity with a level of 28.8 IU/mL. His kidney biopsy showed features of ATIN with no glomerular involvement. Treatment with corticosteroids led to improvement of his kidney function and serology for ANCA became negative. In this case report ATIN seems to be associated with ANCA positivity, in the absence of other obvious causes for the acute tubulo-interstitial insult.Conclusion: ATIN can be associated with positive ANCA without features of renal-limited vasculitis or systemic vasculitis. This can occur in the absence of drug exposure. The outcome in our case was favorable with corticosteroid therapy.Key words: ANCA; Acute Tubulo-interstitial Nephritis; Pathogenesi

In vitro inhibition of Helicobacter pylori urease with non and semi fermented Camellia sinensis

Purpose: Helicobacter pylori is the etiological agent in duodenal and peptic ulcers. The growing problem of antibiotic resistance by the organism demands the search for novel compounds, especially from natural sources. This study was conducted to evaluate the effect of Camellia sinensis extracts on the urease enzyme that is a major colonization factor for H. pylori. Methods: Minimum inhibitory concentrations of nonfermented and semifermented C. sinensis methanol: water extracts were assessed by broth dilution method. Examination of the urease function was performed by Mc Laren method, and urease production was detected on 12% SDS polyacrylamide gel electrophoresis from whole cell and membrane bound proteins. Results: Both extracts had inhibitory effects against H. pylori and urease production. At a concentration of 2.5 mg/ml of nonfermented extract and 3.5 mg/ml of semifermented extract the production of Ure A and Ure B subunits of the urease enzyme were inhibited completely. A concentration of 4 mg/ml of nonfermented and 5.5 mg/ml of semifermented extract were bactericidal for H. pylori. Conclusions: C. sinensis extracts, especially the nonfermented, could reduce H. pylori population and inhibit urease production at lower concentrations. The superior effect of nonfermented extract is due to its rich polyphenolic compounds and catechin contents

Risk Measures At Risk- Are we missing the point? <br>Discussions around sub-additivity and distortion

URL des Documents de travail : http://ces.univ-paris1.fr/cesdp/cesdp2016.htmlDocuments de travail du Centre d'Economie de la Sorbonne 2016.39 - ISSN : 1955-611XThis paper discusses the regulatory requirements (Basel Committee, ECB-SSM andEBA) to measure the major risks of financial institutions, for instance Market, Credit and Operational, regarding the choice of the risk measures, the choice of the distributions used to model them and the level of confidence. We highlight and illustrate paradoxes and issues observed when implementing one approach over another, the inconsistencies between the methodologies suggested and the goals required to achieve them. We focus on the notion of sub-additivity and alternative risk measures, providing the supervisor with some recommendations and risk managers with some tools to assess and manage the risks in a financial institution

Shapley Allocation — the effect of Services on Diversification

URL des Documents de travail : http://ces.univ-paris1.fr/cesdp/cesdp2015.htmlDocuments de travail du Centre d'Economie de la Sorbonne 2015.57 - ISSN : 1955-611XA paraître dans Journal of Business and EconomicsThe Shapley method is applied to capital allocation in the context of a simple business model, where many business units supported by services. In this model the services are capable of either reducing the capital payable by the business units, or the opposite. A simple model of evaluating the value of coalitions is proposed, with a modification if a service is a member of the coalition. A closed form formula for the Shapley allocation to all players is derived, thus eliminating combinatorial problems

Knowledge Discovery in Biological Databases for Revealing Candidate Genes Linked to Complex Phenotypes

Genetics and “omics” studies designed to uncover genotype to phenotype relationships often identify large numbers of potential candidate genes, among which the causal genes are hidden. Scientists generally lack the time and technical expertise to review all relevant information available from the literature, from key model species and from a potentially wide range of related biological databases in a variety of data formats with variable quality and coverage. Computational tools are needed for the integration and evaluation of heterogeneous information in order to prioritise candidate genes and components of interaction networks that, if perturbed through potential interventions, have a positive impact on the biological outcome in the whole organism without producing negative side effects. Here we review several bioinformatics tools and databases that play an important role in biological knowledge discovery and candidate gene prioritization. We conclude with several key challenges that need to be addressed in order to facilitate biological knowledge discovery in the future.&nbsp

The Spectral Stress VaR (SSVaR)

URL des Documents de travail : http://centredeconomiesorbonne.univ-paris1.fr/documents-de-travail/Documents de travail du Centre d'Economie de la Sorbonne 2015.52 - ISSN : 1955-611XOne of the key lessons of the crisis which began in 2007 has been the need to strengthen the risk coverage of the capital framework. In response, the Basel Committee in July 2009 completed a number of critical reforms to the Basel II framework which will raise capital requirements for the trading book and complex securitisation exposures, a major source of losses for many international active banks. One of the reforms is to introduce a stressed value-at-risk (VaR) capital requirement based on a continuous 12-month period of significant financial stress (Basel III (2011) [1]. However the Basel framework does not specify a model to calculate the stressed VaR and leaves it up to the banks to develop an appropriate internal model to capture material risks they face. Consequently we propose a forward stress risk measure “spectral stress VaR” (SSVaR) as an implementation model of stressed VaR, by exploiting the asymptotic normality property of the distribution of estimator of VaR p. In particular to allow SSVaR incorporating the tail structure information we perform the spectral analysis to build it. Using a data set composed of operational risk factors we fit a panel of distributions to construct the SSVaR in order to stress it. Additionally we show how the SSVaR can be an indicator regarding the inner model robustness for the bank