A hybrid data assimilation scheme for model parameter estimation: Application to morphodynamic modelling

We present a novel algorithm for joint state-parameter estimation using sequential three dimensional variational data assimilation (3D Var) and demonstrate its application in the context of morphodynamic modelling using an idealised two parameter 1D sediment transport model. The new scheme combines a static representation of the state background error covariances with a flow dependent approximation of the state-parameter cross-covariances. For the case presented here, this involves calculating a local finite difference approximation of the gradient of the model with respect to the parameters. The new method is easy to implement and computationally inexpensive to run. Experimental results are positive with the scheme able to recover the model parameters to a high level of accuracy. We expect that there is potential for successful application of this new methodology to larger, more realistic models with more complex parameterisations.     

Mathematical Analysis of Chemical Reaction Systems

The use of mathematical methods for the analysis of chemical reaction systems has a very long history, and involves many types of models: deterministic versus stochastic, continuous versus discrete, and homogeneous versus spatially distributed. Here we focus on mathematical models based on deterministic mass-action kinetics. These models are systems of coupled nonlinear differential equations on the positive orthant. We explain how mathematical properties of the solutions of mass-action systems are strongly related to key properties of the networks of chemical reactions that generate them, such as specific versions of reversibility and feedback interactions.     

Risk assessment of war wrecks – a comprehensive approach investigating four wrecks containing munitions in the German Bight/North Sea

Shipwrecks and dumped munition continue to be a major hazard, both in the North Sea but also on a global scale. Research within the EU Interreg project North Sea Wrecks (NSW), in cooperation with the German Aerospace Centre, Institute for the Protection of Maritime Infrastructures (DLR), is generating new insights into the status of wrecks, the potential leakage of pollutants from remaining munitions loads and the effects of contamination on exposed marine organisms in the North Sea environment. Further, historical documents are generated from archives to describe ship's history and sinking scenario. These historical findings were compared to models and images of the visual inspections of the wrecks. Further, samples of water, sediment and organisms are being analysed for traces of explosives. Combining the results of these different fields of research allows for a better understanding of the environmental risks deriving from these wrecks. This process is shown below by focusing on the wreck of the German light cruiser SMS MAINZ, which sank in 1914. Data were compared to three additional wrecks situated also within the southern German Bight. Available data about the wrecks were preliminary assessed using a wreck risk model. Finally, wrecks were ranked according to their potential environmental risk.     

全球盛名且完整的加拿大食品安全体系(之一)

加拿大在食品安全保障方面,在全球范围内一直享有盛名,并拥有一套完整的系统。加拿大联邦政府希望最大限度地保障在加拿大本土上,从食品原料供应→零售→最终消费者,这几个消费过程中的食品安全和健康。在加拿大联邦政府支持,加拿大农业与农业食品部的组织下,笔者对加拿大食品安全的立法、执法、科学管理及教育等几方面进行了考察,并希望以图文并茂的形式与业界分享。     

全球盛名且完整的加拿大食品安全体系(之三)

加拿大在食品安全保障方面,在全球范围内一直享有盏名,并拥有一套完整的系统。加拿大联邦政府希望最大限度地保障在加拿大本土上,从食品原料供应→零售→最终消费者,这几个消费过程中的食品安全和健康。在加拿大联邦政府支持,加拿大农业与农业食品部的组织下,笔者对加拿大食品安全的立法、执法、科学管理及教育等几方面进行了考察,并希望以图文并茂的形式与业界分享。     

Comparison of two models for the estimation of usual intake addressing zero consumption and non-normality

Various models exist for estimating the usual intake distribution from dietary intake data. In this paper, we compare two of these models, the Iowa State University Foods (ISUF) model and the betabinomial-normal (BBN) model and apply them to three different datasets. Intake data are obtained by aggregating over multiple food products and are often non-normal. The ISUF and BBN model both address non-normality. While the two models have similar structures, they show some differences. The ISUF model includes an additional spline transformation for improving the normality of the intake amount distribution, while the BBN model includes the possibility of addressing covariates, such as age or sex. Our analyses showed that for two of the example datasets both models produced similar estimates of the higher percentiles of the usual intake distribution. However, for the third dataset, where the intake amount distribution appear to be multimodal, both models produced different percentile estimates.     

The self-reference effect with imagery encoding.

Reviews studies that have shown that memory for an item is better when that item is encoded with reference to the self than when it is encoded with reference to some other person and examines the work of C. G. Lord (see record 1981-07095-001), who observed a reversal of the self-reference effect and attributed this reversal to use of imagery. The present series of 6 experiments conducted with 261 undergraduates contradicted Lord's hypothesis that the self-reference effect is reversed when Ss use imagery to encode the material. In these experiments, self-reference effects were consistently observed with imagery instructions. It is suggested that the benefit of self-reference results from the use of episodic memory when forming images of the self. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)