7 research outputs found

    Stepwise model parametrisation using satellite imagery and hemispherical photography: tuning AquaCrop sensitive parameters for improved winter wheat yield predictions in semi-arid regions

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    Crop models are complex with many parameters, which has limited their application. Here we present an approach which both removes the model complexity through reducing the parameter dimensionality through sensitivity analysis, and presents a subsequent efficient approach to model parameterisation using swarm optimisation. We do this for two key model outputs, crop canopy and yield, and for two types of observational data, hemispheric photographs and Landsat7 imagery. Importantly we compare the usefulness of these two sources of data in terms of accurate yield prediction. The results showed that the dominant model parameters that predict canopy cover were generally consistent across the fields, with the exception of those related water stress. Although mid-season canopy cover extracted from Landsat7 was underestimated, good agreement was found between the simulated and observed canopy cover for both sources of data. Subsequently, less accurate yield predictions were achieved with the Landsat7 compared to the hemispherical photography-based parametrizations. Despite the small differences in the canopy predictions, the implications for yield prediction were substantial with the parametrization based on hemispherical photography providing far more accurate estimates of yield. There are, however, additional resource implications associated with hemispherical photography. We evaluate these trade-offs, providing model parametrization sets and demonstrating the potential of satellite imagery to assist AquaCrop, particularly on large scales where ground measurements are challenging.This work is part of the SAFA (Sustainable Agriculture For Africa) project which is funded by OCP, Morocco

    AgĂ©nĂ©sie de lÂŽartĂšre pulmonaire droite, Ă  propos d’un cas

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    L’agĂ©nĂ©sie unilatĂ©rale de l’artĂšre pulmonaire est une malformation congĂ©nitale rare. Sa symptomatologie respiratoire est variable : infections respiratoires, gĂȘne Ă  l’effort, hĂ©moptysie. Sur le plan radiologique, cette anomalie peut ĂȘtre Ă©voquĂ©e sur une radiographie thoracique standard mais doit ĂȘtre confirmĂ©e par angiographie. Nous rapportons le cas d’une jeune patiente ĂągĂ©e de 27 ans, prĂ©sentant une dyspnĂ©e stade III de NYHA. Un angioscanner a Ă©tĂ© rĂ©alisĂ© et a objectivĂ© une agĂ©nĂ©sie de l’artĂšre pulmonaire droite. La prise en charge de ces patients n’est pas encore consensuelle Ă  ce jour et dĂ©pend de l’évolution clinique. Cependant il se limite le plus souvent Ă  une surveillance clinique et paraclinique rĂ©guliĂšre afin de dĂ©pister d’éventuelles complications

    Molecular concepts, self-organisation and properties of polysoaps

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