Splitting Arabic Texts into Elementary Discourse Units

International audienceIn this article, we propose the first work that investigates the feasibility of Arabic discourse segmentation into elementary discourse units within the segmented discourse representation theory framework. We first describe our annotation scheme that defines a set of principles to guide the segmentation process. Two corpora have been annotated according to this scheme: elementary school textbooks and newspaper documents extracted from the syntactically annotated Arabic Treebank. Then, we propose a multiclass supervised learning approach that predicts nested units. Our approach uses a combination of punctuation, morphological, lexical, and shallow syntactic features. We investigate how each feature contributes to the learning process. We show that an extensive morphological analysis is crucial to achieve good results in both corpora. In addition, we show that adding chunks does not boost the performance of our system

Modelling prognostic factors in advanced pancreatic cancer

Pancreatic cancer is the fifth most common cause of cancer death. Identification of defined patient groups based on a prognostic index may improve the prediction of survival and selection of therapy. Many prognostic factors have been identified often based on retrospective, underpowered studies with unclear analyses. Data from 653 patients were analysed. Continuous variables are often simplified assuming a linear relationship with log hazard or introducing a step function (dichotomising). Misspecification may lead to inappropriate conclusions but has not been previously investigated in pancreatic cancer studies. Models based on standard assumptions were compared with a novel approach using nonlinear fractional polynomial (FP) transformations. The model based on FP-transformed covariates was most appropriate and confirmed five previously reported prognostic factors: albumin, CA19-9, alkaline phosphatase, LDH and metastases, and identified three additional factors not previously reported: WBC, AST and BUN. The effects of CA19-9, alkaline phosphatase, AST and BUN may go unrecognised due to simplistic assumptions made in statistical modelling. We advocate a multivariable approach that uses information contained within continuous variables appropriately. The functional form of the relationship between continuous covariates and survival should always be assessed. Our model should aid individual patient risk stratification and the design and analysis of future trials in pancreatic cancer

Effects of humidity on tomato (Lycopersicon Esculentum cv. Truss) water uptake, yield, and dehumidification cost

. Effects of humidity effect on tomato (Lycopersicon Esculentum cv. Truss) water uptake, yield, and dehumidification cost. Can. Agric. Eng. 41: 135-140. Air water-vapour pressure deficit is the prime factor controlling plant water uptake in greenhouses. In tum, plant water uptake affects several physiological processes such as pollination, plant growth, and fruit yield. In this study, plant water uptake and fruit yield were measured under four different ambient water-vapour pressure deficits (VPD). Four identical greenhouses were used to produce tomatoes under four different regimes of VPD. Greenhouses #1 and #2 were kept under a low and high VPD, respectively, while greenhouse #3 was kept under a low VPD during the day and a high VPD during the night. Greenhouse #4 was kept under a VPD dynamically controlled to maintain plant water uptake at 800 mUplant per day. Plant water uptake and yield were highly correlated to ambient VPD as greenhouses # 1and #2 produced a low and high water uptake rate and yield, respectively. Greenhouse #3 produced an intermediate water uptake and yield, while greenhouse #4 lead to a water uptake and yield as high as that of greenhouse #2. Dehumidification costs were also highly correlated to VPD, as low VPD produced low water uptake requiring little dehumidification. Thus, managing plant water uptake can lead to a more efficient crop production. L

Biodegradation of cyclic amines by Pseudomonas strain involves an amine monooxygenase.

International audienceLa souche O1G3 de Pseudomonas putida catalyse la dégradation de la pyrrolidine et de la piperidine. Cette souche peut utiliser ces composés en tant que seules sources de carbone, d'azote et d'énergie. Lorsque les amines cycliques ont été utilisés comme substrats de culture, la synthèse d'une mono-oxygénase d'amines héminiques fut induite chez cette bactérie. Nous avons confirmé cette observation à l'aide d'analyses par spectrophotométrie et d'inhibiteurs spécifiques. Cette mono-oxygénase est une enzyme dépendante du NADH et catalyse le clivage du lien C-N de l'anneau de la pyrrolidine et de la piperidine par un mécanisme ressemblant à une désalkylation N. Cette réaction pourrait être suivie par un clivage de l'anneau pour former du ?-aminobutyraldéhyde à son tour oxydé en du ?-aminobutyrate. Des études plus approfondies sont en cours dans le but de purifier la mono-oxygénase renfermant de l'hème