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

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

Agénésie de l´artère pulmonaire droite, à propos d’un cas

L’agénésie unilatérale de l’artère pulmonaire est une malformation congénitale rare. Sa symptomatologie respiratoire est variable : infections respiratoires, gêne à l’effort, hémoptysie. Sur le plan radiologique, cette anomalie peut être évoquée sur une radiographie thoracique standard mais doit être confirmée par angiographie. Nous rapportons le cas d’une jeune patiente âgée de 27 ans, présentant une dyspnée stade III de NYHA. Un angioscanner a été réalisé et a objectivé une agénésie de l’artère pulmonaire droite. La prise en charge de ces patients n’est pas encore consensuelle à ce jour et dépend de l’évolution clinique. Cependant il se limite le plus souvent à une surveillance clinique et paraclinique régulière afin de dépister d’éventuelles complications

Chapter Five - The function, biogenesis and regulation of the electron transport chains in Campylobacter jejuni: new insights into the bioenergetics of a major food-borne pathogen

Campylobacter jejuni is a zoonotic Epsilonproteobacterium that grows in the gastrointestinal tract of birds and mammals, and is the most frequent cause of food-borne bacterial gastroenteritis worldwide. As an oxygen-sensitive microaerophile, C. jejuni has to survive high environmental oxygen tensions, adapt to oxygen limitation in the host intestine and resist host oxidative attack. Despite its small genome size, C. jejuni is a versatile and metabolically active pathogen, with a complex and highly branched set of respiratory chains allowing the use of a wide range of electron donors and alternative electron acceptors in addition to oxygen, including fumarate, nitrate, nitrite, tetrathionate and N- or S-oxides. Several novel enzymes participate in these electron transport chains, including a tungsten containing formate dehydrogenase, a Complex I that uses flavodoxin and not NADH, a periplasmic facing fumarate reductase and a cytochrome c tetrathionate reductase. This review presents an updated description of the composition and bioenergetics of these various respiratory chains as they are currently understood, including recent work that gives new insights into energy conservation during electron transport to various alternative electron acceptors. The regulation of synthesis and assembly of the electron transport chains is also discussed. A deeper appreciation of the unique features of the respiratory systems of C. jejuni may be helpful in informing strategies to control this important pathogen