Augmentation du risque cardiovasculaire et de mortalité chez le patient adulte insuffisant rénal chronique: quand et comment traiter l'hyperphosphatémie en traitement conservateur ? : travail de Bachelor

Introduction: L’insuffisance rénale chronique (IRC) est une pathologie complexe entraînant de nombreuses complication métaboliques, dont l’hyperphosphatémie.Le risque cardiovasculaire (CV) et de mortalité est indirectement proportionnel au débit de filtration glomérulaire et directement proportionnel à la phosphatémie. Les recommandations données par les sociétés savantes pour traiter l’hyperphosphatémie sont peu concrètes et hétérogènes. En l’absence de consensus des guidelines, les diététiciens(nes) manquent d’indications claires pour optimiser la prise en charge nutritionnelle de l’hyperphosphatémie chez les patients adultes avec IRC en traitement conservateur, population choisie pour notre travail de Bachelor. But: Notre première question de recherche (QdR n°1) vise à établir à partir de quel seuil de phosphatémie le risque CV et/ou de mortalité augmente, pour déterminer à partir de quand une intervention nutritionnelle se révèle nécessaire. Notre deuxième question de recherche (QdR n°2) vise à mettre en lumière les priorités de la prise en charge nutritionnelle concernant le P selon les guidelines et les études publiées après les derniers guidelines, qui datent de 2010. Méthode: Afin de répondre à la QdR n°1, nous avons effectué une revue systématique sur plusieurs bases de données à partir de janvier 2011 jusqu’à mai 2017. Ensuite, une revue narrative comprenant une analyse des guides de recommandations et des études récentes (2013-2017) nous a permis de répondre à la QdR n°2. Résultats: Notre revue systématique inclut dix études, dont sept de cohorte et trois transversales. Neuf études ont trouvé une association significative entre un seuil de phosphatémie situé entre 1.20 et 1.62 mmol/l (3.72-5.01 mg/dl) et l’augmentation du risque CV et/ou de mortalité chez les patients avec IRC en traitement conservateur. D’après notre revue narrative, les priorités de la prise en cahrge de l’hyperphosphatémie selon les guidelines sont: la restriction des apports alimentaires en phosphore (P) et l’utilisation de chélateurs de P. Les études récentes relèvent néanmoins que l’association en apports en P et phosphatémie demeure hypothétique et que l’efficacité des chélateurs n’a pas été prouvé chez la population IRC en traitement conservateur. De plus, la biodisponibilité du P serait plus importante que la quantité consommée. Conclusion: Lorsque la phosphatémie se situe à la limite supérieure des normes de laboratoire (≤ 1.45 mmol/l), une intervention nutritionnelle concernant le P serait déjà nécessaire. Toutefois, les priorités de cette intervention restent controversées. Des essais contrôlés randomisés sont nécessaires pour déterminer l’impact réel des apports alimentaires en P sur la phosphatémie et pour évaluer le bénéfice réel des interventions visant à diminuer la phosphatémie sur le risque CV et/ou de mortalité chez notre population d’intérêt

Finite time corrections in KPZ growth models

We consider some models in the Kardar-Parisi-Zhang universality class, namely the polynuclear growth model and the totally/partially asymmetric simple exclusion process. For these models, in the limit of large time t, universality of fluctuations has been previously obtained. In this paper we consider the convergence to the limiting distributions and determine the (non-universal) first order corrections, which turn out to be a non-random shift of order t^{-1/3} (of order 1 in microscopic units). Subtracting this deterministic correction, the convergence is then of order t^{-2/3}. We also determine the strength of asymmetry in the exclusion process for which the shift is zero. Finally, we discuss to what extend the discreteness of the model has an effect on the fitting functions.Comment: 34 pages, 5 figures, LaTeX; Improved version including shift of PASEP height functio

Random Growth Models

The link between a particular class of growth processes and random matrices was established in the now famous 1999 article of Baik, Deift, and Johansson on the length of the longest increasing subsequence of a random permutation. During the past ten years, this connection has been worked out in detail and led to an improved understanding of the large scale properties of one-dimensional growth models. The reader will find a commented list of references at the end. Our objective is to provide an introduction highlighting random matrices. From the outset it should be emphasized that this connection is fragile. Only certain aspects, and only for specific models, the growth process can be reexpressed in terms of partition functions also appearing in random matrix theory.Comment: Review paper; 24 pages, 4 figures; Minor correction

The characterization of mechanical behaviour on kenaf fibre / polypropylene composites

Global demand for wood plastic composite (WPC) has increased due to the increase of population and latest applications primarily in Malaysia industry today such as decking, chair and ceiling. However, the current WPC is worth investigating since such materials can be explored by enhancing their strength and quality through the treatment method. The objective of this study is to identify the effect of alkaline treatment on kenaf fibre in WPC system, to investigate the highest strength of kenaf fibre loading on mechanical properties in WPC, and to evaluate the morphology characteristics from fracture specimens related to the mechanical testing via scanning electron microscopy (SEM). Specimen was fabricated via injection moulding and hydraulic hot press using kenaf fibre (KF) as filler and polypropylene (PP) as the matrix. A tensile test was carried out to determine the tensile stress of the material. The result revealed treated specimen possesses high tensile stress at 5 wt.% sodium hydroxide (NaOH) compared to 10 wt.% and 20 wt.%. The optimum tensile stress was at 40 wt.% KF (5 wt.% NaOH, 5 wt.% MAPP) with the value 21.38 MPa. Flexural test was carried out on untreated and treated KF which is pure PP, 10 wt.% KF, and 20 wt.% KF by weight to PP. The result of flexural stress showed treated specimen lead better flexural at 20 wt.% PP/KF (5 wt.% NaOH) with 30.25 MPa. Meanwhile 40 wt.% KF (5 wt.% MAPP) give high fatigue life cycles at all stress level 90 %, 80 %, 70 %, 60 % and 50 % as the specimen structure less damage was induced during fatigue test. SEM is used to observe the morphological characteristics of PP/KF. The good interfacial bonding between KF and PP is 5 wt.% NaOH due of less impurities and lignin content. Overall 5 wt. % NaOH with 40 wt.% PP/KF (5 wt.% MAPP) showed the best result and it is worth to replace the current kenaf fibre polymer composites product

Limit processes for TASEP with shocks and rarefaction fans

We consider the totally asymmetric simple exclusion process (TASEP) with two-sided Bernoulli initial condition, i.e., with left density rho_- and right density rho_+. We consider the associated height function, whose discrete gradient is given by the particle occurrences. Macroscopically one has a deterministic limit shape with a shock or a rarefaction fan depending on the values of rho_{+/-}. We characterize the large time scaling limit of the fluctuations as a function of the densities rho_{+/-} and of the different macroscopic regions. Moreover, using a slow decorrelation phenomena, the results are extended from fixed time to the whole space-time, except along the some directions (the characteristic solutions of the related Burgers equation) where the problem is still open. On the way to proving the results for TASEP, we obtain the limit processes for the fluctuations in a class of corner growth processes with external sources, of equivalently for the last passage time in a directed percolation model with two-sided boundary conditions. Additionally, we provide analogous results for eigenvalues of perturbed complex Wishart (sample covariance) matrices.Comment: 46 pages, 3 figures, LaTeX; Extended explanations in the first two section