The performance of the EU-Rotate_N model in predicting the growth and nitrogen uptake of rotations of field vegetable crops in a Mediterranean environment

The EU-Rotate_N model was developed as a tool to estimate the growth and nitrogen (N) uptake of vegetable crop rotations across a wide range of European climatic conditions and to assess the economic and environmental consequences of alternative management strategies. The model has been evaluated under field conditions in Germany and Norway and under greenhouse conditions in China. The present work evaluated the model using Italian data to evaluate its performance in a warm and dry environment. Data were collected from four 2-year field rotations, which included lettuce (Lactuca sativa L.), fennel (Foeniculum vulgare Mill.), spinach (Spinacia oleracea L.), broccoli (Brassica oleracea L. var. italica Plenck) and white cabbage (B. oleracea convar. capitata var. alba L.); each rotation used three different rates of N fertilizer (average recommended N1, assumed farmer's practice N2=N1+0·3×N1 and a zero control N0). Although the model was not calibrated prior to running the simulations, results for above-ground dry matter biomass, crop residue biomass, crop N concentration and crop N uptake were promising. However, soil mineral N predictions to 0·6 m depth were poor. The main problem with the prediction of the test variables was the poor ability to capture N mineralization in some autumn periods and an inappropriate parameterization of fennel. In conclusion, the model performed well, giving results comparable with other bio-physical process simulation models, but for more complex crop rotations. The model has the potential for application in Mediterranean environments for field vegetable production

Estimation of uncertainty in flood forecasts - a comparison of methods

The scientific literature has many methods for estimating uncertainty, however, there is a lack of information about the characteristics, merits and limitations of the individual methods, particularly for making decisions in practice. This paper provides an overview of the different uncertainty methods for flood forecasting that are reported in literature, concentrating on two established approaches defined as the ensemble and the statistical approach. Owing to the variety of flood forecasting and warning systems in operation, the question ‘which uncertainty method is most suitable for which application’ is difficult to answer readily. The paper aims to assist practitioners in understanding how to match an uncertainty quantification method to their particular application using two flood forecasting system case studies in Belgium and Canada. These two specific applications of uncertainty estimation from the literature are compared, illustrating statistical and ensemble methods, and indicating the information and output that these two types of methods offer. The advantages, disadvantages and application of the two different types of method are identified. Although there is no one ‘best’ uncertainty method to fit all forecasting systems, this review helps to explain the current commonly used methods from the available literature for the non-specialist

Pharmacokinetic-Pharmacodynamic Characterization of the Cardiovascular, Hypnotic, EEG and Ventilatory Responses to Dexmedetomidine in the Rat 1 ABBREVIATIONS: MAP, mean arterial pressure; PK, pharmacokinetic; PD, pharmacodynamic; bpm, beats per minute

ABSTRACT This study characterizes the pharmacokinetic-pharmacodynamic (PK-PD) relationships of the cardiovascular, EEG, hypnotic and ventilatory effects of the alpha-2 adrenergic agonist dexmedetomidine in rats. Dexmedetomidine was administered by a single rapid infusion (n ϭ 6) and by an infusion regimen of gradually increasing rate (n ϭ 8). HR, mean arterial pressure (MAP) and EEG signals were recorded continuously, as was the time at which the rats woke up spontaneously from druginduced sleep, a measure of hypnosis. Arterial concentrations of dexmedetomidine and blood gases were determined regularly. A sigmoidal E max model was used to describe the HR, MAP and EEG concentration-effect relationships, with the EEG effect (activity in 0.5-3.5-Hz frequency band) linked to an effect-site model. The PK of dexmedetomidine could be described by a two-compartment model, with similar PK parameters for both infusion regimens. Plasma protein binding was 84.1[0.7]%. Because of complex cardiovascular homeostatic reflex mechanisms, HR and MAP could only be analyzed during gradually increasing infusions. The maximal decrease in HR was 35(2)%, and the maximal increase in MAP was 37(2)%. For both infusion regimens, similar PD parameters were found for the EEG and the hypnotic measure. These data suggest the absence of active metabolites or tolerance of the EEG and hypnotic effects. Judging on the basis of concentrations of dexmedetomidine (mean (S.E.M.)), HR decrease was the most sensitive response [EC 50 of 0.65(0.09) ng/ml], followed by increase in MAP [EC 50 of 2.01(0.14) ng/ml], change in EEG activity [EC 50 of 2.24(0.16) ng/ml] and the hypnotic measure [C wake-up of 2.64(0.10) ng/ml]. Ventilatory effects were minor. Alpha-2 adrenergic agonists, such as clonidine, have been used in clinical practice as antihypertensive agents for almost 30 years. Recently, clonidine and a more selective alpha-2 adrenergic agonist, dexmedetomidine, have received considerable attention in anesthetic practice because of their analgesic, sedative, hypnotic and anxiolytic effects In order to develop a safe and rational dosing regimen for dexmedetomidine, most researchers have followed its effects over time as a function of dose in human subjects or in animals. An alternative approach is to study dexmedetomidine's pharmacology on the basis of concentrations rather than dose to establish PK-PD relationships for its desired anesthetic effects, such as sedation and hypnosis, and its unwanted side effects, such as blood pressure increase and HR decrease. This would make it possible to predict the time-course of therapeutic and side effect profiles of dexmedetomidine for i.v. dosing strategies. However, the design of such PK-PD experiments is often restricted in human subjects, because they require the evaluation of multiple effect measures at a wide range of concentrations (e.g.