128 research outputs found

    Using a Crop Model to Benchmark Miscanthus and Switchgrass

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    Crop yields are important items in the economic performance and the environmental impacts of second-generation biofuels. Since they strongly depend on crop management and pedoclimatic conditions, it is important to compare candidate feedstocks to select the most appropriate crops in a given context. Agro-ecosystem models offer a prime route to benchmark crops, but have been little tested from this perspective thus far. Here, we tested whether an agro-ecosystem model (CERES-EGC) was specific enough to capture the differences between miscanthus and switchgrass in northern Europe. The model was compared to field observations obtained in seven long-term trials in France and the UK, involving different fertilizer input rates and harvesting dates. At the calibration site (Estrées-Mons), the mean deviations between simulated and observed crop biomass yields for miscanthus varied between −0.3 t DM ha−1 and 4.2 t DM ha−1. For switchgrass, simulated yields were within 1.0 t DM ha−1 of the experimental data. Observed miscanthus yields were higher than switchgrass yields in most sites and for all treatments, with one exception. Overall, the model captured the differences between both crops adequately, with a mean deviation of 0.46 t DM ha−1, and could be used to guide feedstock selections over larger biomass supply areas

    Greenhouse gas abatement strategies and costs in French dairy production

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    The French dairy sector—like the rest of the economy—has to address the challenge of mitigating greenhouse gas (GHG) emissions to curb climate change. Deciding the economically optimal mitigation level and mix of abatement strategies requires knowledge on the cost of reducing GHG emissions. Agricultural bio-economic models can help identify which production-system changes are needed to reduce GHG emissions at different levels of incentives at minimal cost. The results reflect the model structure and parameter set, especially for GHG emissions accounting. Here abatement strategies and related costs for several levels of tax on GHG emissions in French dairy production are compared using four bio-economic models: the three supply models AROPAj, ORFEE and FARMDYN and the global partial equilibrium model GLOBIOM. It is found that between 1% and 6% GHG emissions abatement can be achieved at the current price of the EU allowances without substantially reducing milk production or outsourcing input production such as feed or herd renewal. Costs reflect the planning horizon: mitigation is more expensive when past investments are not amortized. Models that account for demand-side factors show a carbon tax has potential negative impacts on consumers through higher milk prices, but could nevertheless partly offset the reduction in income of farmers simulated by farm models. Model results suggest that promising on-farm GHG emissions abatement strategies include measures that let animals reach their full production potential and moderately intensive land management

    Review of mathematical programming applications in water resource management under uncertainty

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    Vertical banded gastroplasty: long-term results comparing three different techniques.

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    BACKGROUND: Vertical banded gastroplasty (VBG) has been our procedure of choice for the treatment of morbid obesity from 1981-1995, at which time it was replaced by laparoscopic gastric banding. Three different techniques have been used for banding: silastic band, marlex mesh, adjustable sphincter. The purpose of this paper is to present the long-term results. METHODS: The charts from all patients operated on during the aforementioned period were reviewed and the data analysed retrospectively. RESULTS: This series comprises 197 patients, 172 females and 25 males, with a mean initial excess weight of 94.8% (6-300%) and a mean initial Body Mass Index (BMI) of 42.9 kg/m2 (23-88 kg/m2). 73 patients had a silastic band, 40 Marlex mesh, and 84 an adjustable sphincter. Overall excess weight loss was 66% after 12-24 months, and remained between 50 and 60% up to 9 years postoperatively. There was no difference between the 3 groups. 82 patients (41%) developed a total of 117 complications during follow-up. Among them were stenosis 20%, staple-line disruption 11%, incisional hernia 13%, severe esophagitis 7% and band migration 1.5%. Stenosis developed more often with a silastic band or an adjustable sphincter, and severe esophagitis was more prevalent after the adjustable sphincter. 58 patients required one or more procedures for correction, including dilatation in 21, band removal in 17, band replacement in 15, restapling in 19 and incisional hernia repair in 11 patients. Overall, 29.4% of patients had to be reoperated. There were more reoperations in the silastic and adjustable sphincter groups compared with the Marlex mesh group. CONCLUSIONS: VBG is associated with a rapid weight loss that is relatively well-maintained over time, although there is a tendency to slight weight regain after 2 years. The price for these results is high if complications and further necessary procedures are considered, especially after banding with a silastic band or an adjustable sphincter. Marlex mesh represents the banding material of choice if VBG is chosen

    Thrombocytopénie après remplacement valvulaire aortique chirurgical par bioprothèse sutureless Livanova Perceval S

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    Objectif L’origine et l’incidence des thrombocytopénies après remplacement de valve aortique avec la bioprothèse Perceval S restent peu clairs. Les objectifs de cette étude rétrospective sont de déterminer l'incidence et l'évolution de la thrombocytopénie post-opératoire après un remplacement valvulaire aortique avec la Perceval S, de déterminer si cette thrombopénie a un impact sur la morbi-mortalité à court terme (30 jours) et si elle provoque plus de reprise opératoire pour des troubles de l’hémostase (décaillotage, saignement, drainage péricardique). Nous souhaitons également définir si la thrombocytopénie était provoquée par une hémolyse augmentée ou une réaction inflammatoire plus importante. Matériel et méthode Les données proviennent de 156 patients ayant reçu soit la bioprothèse en péricarde sutureless Perceval S (n = 103) soit la bioprothèse en péricarde sur armature type St Jude Trifecta (n = 53) entre mars 2016 et août 2019. Les données cliniques et biologiques récoltées ont été comparées entres elles. Le test T de Student apparié a servi à évaluer les différences entre les deux groupes. Toutes les p-values <0.05 ont été considérées comme significatives. Résultats L’utilisation de la Perceval S induisait une baisse plus importante du profil plaquettaire. La mesure la plus basse se situait à J3 pour les 2 groupes mais la thrombocytopénie était plus importante pour la Perceval S avec une mesure à 89.2±37.7 G/L vs 106.5±34.1 G/L pour le groupe Trifecta (P=0.01). Nous avons retrouvé une mortalité intra hospitalière post-opératoire identique à 2% pour les deux groupes (P=0.98). Le taux de ré-opération pour complications (décaillotage, saignement, drainage péricardique) était de 4 % pour la Perceval S vs 7.5% pour la Trifecta (P=0.45). Nous n’avons pas retrouvé de différences significatives aux mesures des lactates déshydrogénases (LDH) (1 semaine post-opératoire groupe P 431.4±607.2 U/L vs 474.7±672.3 U/L pour le groupe T (P=0.73)), de la CRP (1 semaine post-opératoire groupe P 143.5±69.3 mg/L vs 145.4±68.2 mg/L pour le groupe T (P=0.87)) ou encore des globules blanche (WBC) (1 semaine post-opératoire groupe P 12.5±4.0 x 109/L vs 13.0±4.2 x 109/L pour le groupe T (P=0.44)). Conclusion La valve Perceval S, comme les autres valves sutureless (SU-DR), est un dispositif sûr qui s’ajoute à l’arsenal thérapeutique du chirurgien. Cette valve se démarque par sa facilité et rapidité d’implantation. Nous avons pu objectiver une thrombocytopénie plus importante pour le groupe Perceval mais sans que celle-ci n’augmentent la morbi-mortalité à court terme. Il n’y a pas plus de reprise opératoire pour des troubles de l’hémostase et le syndrome inflammatoire et l’hémolyse post- opératoire sont similaires pour les 2 groupes
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