98 research outputs found

    La prévision des précipitations par recherche d'analogues : état de l'art et perspectives

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    La prévision des précipitations par analogie, adaptée des sorties de modèles numériques de prévision, s'est améliorée ces dix dernières années et est actuellement implémentée opérationnellement dans diverses infrastructures françaises. Le premier objectif de cette étude est de dresser l'état de l'art de cette approche. L'application de cette méthode nécessite une base de données contenant les champs des variables qui permettent de caractériser les situations météorologiques passées. Etant donné qu'il existe deux archives de génération différente (réanalyses ERA-40 et NCEP/NCAR), la sensibilité de cette méthode de prévision au choix de l'archive a été étudiée. Les résultats révèlent une faible sensibilité, même si de manière générale les performances sont légèrement supérieures avec l'archive ERA-40, notamment pour les événements pluvieux extrêmes. Enfin, des perspectives d'amélioration de la méthode susceptibles d'être exploitées à court terme sont évoquées. / Precipitation forecasting based on an adaptation of model outputs through an analog sorting technique has been improved for around ten years. The method runs operationally in several French institutions. First, this short paper presents the state of the art of this approach and the more recent developments. Second, a sensitivity analysis to the choice of the database from which the variables that characterise the past meteorological situations are extracted is performed. Two available archives are tested (ERA-40 and NCEP/NCAR re-analyses). The results show that despite the performances obtained with the ERA-40 database are slightly better, especially for heavy rainfall events, the sensitivity is weak. Finally, further ways for improvement that could be investigated are suggested

    Remote sensing evapotranspiration in ensemble-based framework to enhance cascade routing and re-infiltration concept in integrated hydrological model applied to support decision making

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    Integrated hydrological models (IHMs) help characterize the complexity of surface–groundwater interactions. The cascade routing and re-infiltration (CRR) concept, recently applied to a MODFLOW 6 IHM, improved conceptualization and simulation of overland flow processes. The CRR controls the transfer of rejected infiltration and groundwater exfiltration from upslope areas to adjacent downslope areas where that water can be evaporated, re-infiltrated back to subsurface, or discharged to streams as direct runoff. The partitioning betweenthese three components is controlled by uncertain parameters that must be estimated. Thus, by quantifying and reducing those uncertainties, next to uncertainties of the other model parameters (e.g. hydraulic and storageparameters), the reliability of the CRR is improved and the IHM is better suited for decision support modelling, the two key objectives of this work. To this end, the remotely sensed MODIS-ET product was incorporated into the calibration process for complementing traditional hydraulic head and streamflow observations. A total of approximately 150,000 observations guided the calibration of a 13-year MODFLOW 6 IHM simulation of the Sardon catchment (Spain) with daily stress periods. The model input uncertainty was represented by grid-cellscale parameterization, yielding approximately 500,000 unknown input parameters to be conditioned. The calibration was carried out through an iterative ensemble smoother. Incorporating the MODIS-ET data improved the CRR implementation, and reduced uncertainties associated with other model parameters. Additionally, it significantly reduced the uncertainty associated with net recharge, a critical flux for water management that cannot be directly measured and rather is commonly estimated by IHM simulations

    Non-Invasive Detection of Coronary Artery Disease in Patients With Left Bundle Branch Block Using 64-Slice Computed Tomography

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    ObjectivesThe goal of this study was to evaluate the diagnostic accuracy of 64-slice computed tomography (CT) to identify coronary artery disease (CAD) in patients with complete left bundle branch block (LBBB).BackgroundLeft bundle branch block increases risk of cardiac mortality, and prognosis is primarily determined by the underlying coronary disease. Non-invasive stress tests have limited performance, and conventional coronary angiography (CCA) is usually required.MethodsSixty-six consecutive patients with complete LBBB and sinus rhythm admitted for CCA were enrolled. Computed tomography was performed 3 ± 3.9 days before CCA. The accuracy of 64-slice CT to detect significant stenosis (>50% lumen narrowing) was compared with quantitative coronary angiography. All segments were analyzed regardless of image quality from coronary calcification or motion artifacts. Results were analyzed by patient and by coronary segment (990) using the American Heart Association 15-segment model.ResultsLower heart rates were associated with improved image quality. Computed tomography correctly identified 35 of 37 (95%) patients without significant stenosis and 28 of 29 (97%) patients with significant stenosis on CCA. Computed tomography correctly assessed 68 of 94 (72%) significant stenosis. Overall, accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of 64-slice CT for identifying CAD by patient was 95%, 97%, 95%, 93%, and 97%, respectively, and by segment was 97%, 72%, 99%, 91%, and 97%, respectively.ConclusionsIn a routine clinical practice, 64-slice CT detects with excellent accuracy a significant CAD in patients with complete LBBB. A normal CT in this clinical setting is a robust tool to act as a filter and avoid invasive diagnostic procedures

    Enjeux de conservation d’une zone humide d’eau douce méditerranéenne exceptionnelle : la Garâa Sejenane (Tunisie septentrionale)

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    Cet article a pour but d’évaluer les enjeux de conservation concernant la végétation hydrophytique de la plus grande zone humide naturelle d’eau douce de Tunisie, la Garâa Sejenane. Les 55 relevés phytosociologiques réalisés révèlent une richesse floristique exceptionnelle, avec 74 hydrophytes dont 26 sont à forte valeur patrimoniale. Des analyses multivariées (AFC, CHA) effectuées sur ces données distinguent trois types d’habitats : des cultures inondables, des marais temporaires, et des pelouses humides/mares temporaires. Leur cartographie montre une structure en 3 zones concentriques : une ceinture externe constituée de pelouses humides, de mares temporaires et de prairies fourragères sèches, une zone intermédiaire occupée par des marais temporaires et des prairies fourragères humides, et une zone centrale formée de cultures inondables. Un Indice de Rareté des Espèces très élevé, et des espèces à fort enjeu conservatoire (1 endémique stricte à la Garâa Sejenane, 5 espèces dont elle constitue l’unique localité tunisienne, et 2 espèces dont elle abrite les plus grandes populations nord-africaines) révèlent l’intérêt écologique et conservatoire majeur du site, et ceci malgré de fortes pressions anthropiques subies depuis les années 60. Dans le contexte actuel d’augmentation de la pression de perturbation, la conservation à long terme de cette biodiversité exceptionnelle nécessite la mise en place de mesures de gestion appropriées intégrant les populations locales.This study addresses the conservation issues of the hydrophytic vegetation of Garâa Sejenane, the largest natural freshwater wetland in Tunisia. Fifty-five phytosociological relevés reveal the exceptional floristic wealth, including 74 hydrophytes of which 26 are patrimonial species. Multivariate analyses (CA, AHC) differentiate three types of habitats: flooded crops, temporary marshes, and wet lawns/temporary pools. Their mapping shows concentric zones, including an external belt of wet lawns, temporary pools and dry fodder meadows, an intermediate belt of temporary marshes and wet fodder meadows, and a central area of flood crops. A high Species Rarity Index and the occurrence of several species with high conservation values (1 strictly endemic species to the Garâa Sejenane, 5 others that exist in Tunisia only in this site, and 2 species whose local populations are the largest in North Africa) confirm the major ecological and conservatory interest of the site, despite anthropogenic pressures on the Garâa Sejenane since the sixties. In the present-day context of increasing human pressure, the long-term conservation of this exceptional biodiversity needs the implementation of targeted management measures integrating local populations

    Adam Smith’s Green Thumb and Malthus’ Three Horsemen: Cautionary tales from classical political economy

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    This essay identifies a contradiction between the flourishing interest in the environmental economics of the classical period and a lack of critical parsing of the works of its leading representatives. Its focus is the work of Adam Smith and Thomas Malthus. It offers a critical analysis of their contribution to environmental thought and surveys the work of their contemporary devotees. It scrutinizes Smith's contribution to what Karl Polanyi termed the "economistic fallacy," as well as his defenses of class hierarchy, the "growth imperative" and consumerism. It subjects to critical appraisal Malthus's enthusiasm for private property and the market system, and his opposition to market regulation. While Malthus's principal attraction to ecological economists lies in his having allegedly broadened the scope of economics, and in his narrative of scarcity, this article shows that he, in fact, narrowed the scope of the discipline and conceptualized scarcity in a reified and pseudo-scientific way

    Fusion transcripts and their genomic breakpoints in polyadenylated and ribosomal RNA-minus RNA sequencing data

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    BACKGROUND: Fusion genes are typically identified by RNA sequencing (RNA-seq) without elucidating the causal genomic breakpoints. However, non–poly(A)-enriched RNA-seq contains large proportions of intronic reads that also span genomic breakpoints. RESULTS: We have developed an algorithm, Dr. Disco, that searches for fusion transcripts by taking an entire reference genome into account as search space. This includes exons but also introns, intergenic regions, and sequences that do not meet splice junction motifs. Using 1,275 RNA-seq samples, we investigated to what extent genomic breakpoints can be extracted from RNA-seq data and their implications regarding poly(A)-enriched and ribosomal RNA–minus RNA-seq data. Comparison with whole-genome sequencing data revealed that most genomic breakpoints are not, or minimally, transcribed while, in contrast, the genomic breakpoints of all 32 TMPRSS2-ERG–positive tumours were present at RNA level. We also revealed tumours in which the ERG breakpoint was located before ERG, which co-existed with additional deletions and messenger RNA that incorporated intergenic cryptic exons. In breast cancer we identified rearrangement hot spots near CCND1 and in glioma near CDK4 and MDM2 and could directly associate this with increased expression. Furthermore, in all datasets we find fusions to intergenic regions, often spanning multiple cryptic exons that potentially encode neo-antigens. Thus, fusion transcripts other than classical gene-to-gene fusions are prominently present and can be identified using RNA-seq. CONCLUSION: By using the full potential of non–poly(A)-enriched RNA-seq data, sophisticated analysis can reliably identify expressed genomic breakpoints and their transcriptional effects

    Identification and Replication of Loci Involved in Camptothecin-Induced Cytotoxicity Using CEPH Pedigrees

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    To date, the Centre d'Etude Polymorphism Humain (CEPH) cell line model has only been used as a pharmacogenomic tool to evaluate which genes are responsible for the disparity in response to a single drug. The purpose of this study was demonstrate the model's ability to establish a specific pattern of quantitative trait loci (QTL) related to a shared mechanism for multiple structurally related drugs, the camptothecins, which are Topoisomerase 1 inhibitors. A simultaneous screen of six camptothecin analogues for in vitro sensitivity in the CEPH cell lines resulted in cytotoxicity profiles and orders of potency which were in agreement with the literature. For all camptothecins studied, heritability estimates for cytotoxic response averaged 23.1±2.6%. Nonparametric linkage analysis was used to identify a relationship between genetic markers and response to the camptothecins. Ten QTLs on chromosomes 1, 3, 5, 6, 11, 12, 16 and 20 were identified as shared by all six camptothecin analogues. In a separate validation experiment, nine of the ten QTLs were replicated at the significant and suggestive levels using three additional camptothecin analogues. To further refine this list of QTLs, another validation study was undertaken and seven of the nine QTLs were independently replicated for all nine camptothecin analogues. This is the first study using the CEPH cell lines that demonstrates that a specific pattern of QTLs could be established for a class of drugs which share a mechanism of action. Moreover, it is the first study to report replication of linkage results for drug-induced cytotoxicity using this model. The QTLs, which have been identified as shared by all camptothecins and replicated across multiple datasets, are of considerable interest; they harbor genes related to the shared mechanism of action for the camptothecins, which are responsible for variation in response

    Elective surgery cancellations due to the COVID-19 pandemic: global predictive modelling to inform surgical recovery plans.

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    BACKGROUND: The COVID-19 pandemic has disrupted routine hospital services globally. This study estimated the total number of adult elective operations that would be cancelled worldwide during the 12 weeks of peak disruption due to COVID-19. METHODS: A global expert response study was conducted to elicit projections for the proportion of elective surgery that would be cancelled or postponed during the 12 weeks of peak disruption. A Bayesian β-regression model was used to estimate 12-week cancellation rates for 190 countries. Elective surgical case-mix data, stratified by specialty and indication (surgery for cancer versus benign disease), were determined. This case mix was applied to country-level surgical volumes. The 12-week cancellation rates were then applied to these figures to calculate the total number of cancelled operations. RESULTS: The best estimate was that 28 404 603 operations would be cancelled or postponed during the peak 12 weeks of disruption due to COVID-19 (2 367 050 operations per week). Most would be operations for benign disease (90·2 per cent, 25 638 922 of 28 404 603). The overall 12-week cancellation rate would be 72·3 per cent. Globally, 81·7 per cent of operations for benign conditions (25 638 922 of 31 378 062), 37·7 per cent of cancer operations (2 324 070 of 6 162 311) and 25·4 per cent of elective caesarean sections (441 611 of 1 735 483) would be cancelled or postponed. If countries increased their normal surgical volume by 20 per cent after the pandemic, it would take a median of 45 weeks to clear the backlog of operations resulting from COVID-19 disruption. CONCLUSION: A very large number of operations will be cancelled or postponed owing to disruption caused by COVID-19. Governments should mitigate against this major burden on patients by developing recovery plans and implementing strategies to restore surgical activity safely

    The Acinetobacter baumannii website (Ab-web): a multidisciplinary knowledge hub, communication platform, and workspace

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    Acinetobacter baumannii is a Gram-negative bacterium increasingly implicated in hospital-acquired infections and outbreaks. Effective prevention and control of such infections are commonly challenged by the frequent emergence of multidrug-resistant strains. Here we introduce Ab-web (https://www.acinetobacterbaumannii.no), the first online platform for sharing expertise on A. baumannii. Ab-web is a species-centric knowledge hub, initially with ten articles organized into two main sections, ‘Overview’ and ‘Topics’, and three themes, ‘epidemiology’, ‘antibiotic resistance’, and ‘virulence’. The ‘workspace’ section provides a spot for colleagues to collaborate, build, and manage joint projects. Ab-web is a community-driven initiative amenable to constructive feedback and new ideas
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