Application and optimization of PML ABC for the 3-D wave equation in the time domain

A three-dimensional algorithm with the perfectly matched layer (PML) absorbing boundary condition (ABC) for the scalar wave equation in the time domain is presented for general inhomogeneous lossy or loss-free problems. The proposed PML ABC is applicable to practical finite difference schemes treating the time-domain wave equation, such as the time-domain wave-potential (TDWP) technique and the time-domain scalar wave equation approaches to the analysis of optical structures. The time-domain wave equation for lossy media is expressed in terms of stretched coordinate variables. The algorithm is tested for homogeneous and inhomogeneous media. We demonstrate applications to open (radiation) problems and to port terminations in high-frequency circuit problems. New PML conductivity profiles are developed for use with the second order wave equation, which offer lower reflections in a wider frequency band in comparison with the commonly used (in finite-difference time-domain (FDTD) algorithms) profiles. The effect of the termination walls on the overall PML performance is studied and the best choices are singled out.     

Bayesian state estimation of a flexible industrial robot

A sensor fusion method for state estimation of a flexible industrial robot is developed. By measuring the acceleration at the end-effector, the accuracy of the arm angular position, as well as the estimated position of the end-effector are improved. The problem is formulated in a Bayesian estimation framework and two solutions are proposed; the extended Kalman filter and the particle filter. In a simulation study on a realistic flexible industrial robot, the angular position performance is shown to be close to the fundamental Cramér-Rao lower bound. The technique is also verified in experiments on an ABB robot, where the dynamic performance of the position for the end-effector is significantly improved.     

Inflationary bibliometric values: The role of scientific collaboration and the need for relative indicators in evaluative studies

Several research studies and reports on national and European science and technology indicators have recently presented figures reflecting intensifying scientific collaboration and increasing citation impact in practically all science areas and at all levels of aggregation. The main objective of this paper is twofold, namely first to analyse if the number or weight of actors in scientific communication has increased, if patterns of documented scientific communication and collaboration have changed in the last two decades and if these tendencies have inflationary features. The second question is concerned with the role of scientific collaboration in this context. In particular, the question will be answered to what extent co-authorship and publication activity, on one hand, and co-authorship and citation impact, on the other hand, do interact. The answers found to these questions have strong implication for the application of bibliometric indicators in research evaluation, moreover, the construction of indicators applied to trend analyses and studies based on medium-term or long-term observations have to be reconsidered to guarantee the validity of conclusions drawn from bibliometric results. This revised version was published online in June 2006 with corrections to the Cover Date.     

Evaluation of the chemical composition of fresh and stored edible aroids

The chemical compositions of 32 cultivars of two edible aroid species (Colocasia esculenta var antiquorum and Xanthosoma sagittifolium) were determined. Mean values obtained for both species in g kg^?1 dry weight were: crude protein 37.5–73.6, total fat 0.9–8.7, ash 28.7–77.7, crude fibre 4.3–42.0, total sugars 5.9–42.5 and starch 509.1–705.7. The mam sugars identified by HPLC were fructose, glucose, sucrose and maltose. The amino acids with the highest concentrations were aspartic acid, glutamic acid and arginine. A significant reduction in starch content (to 39.8–47.4 g kg^?1) and increase in total sugars content (to 8.0–11.6 g kg^?1) occurred during the storage of cormels for two weeks under tropical ambient conditions (24–29°C; 86–98% RH). No significant differences (P> 0.05) between fresh and stored cormels were found in crude protein and amino acid contents.     

Pharmacobehavioural evidence for nitric oxide and noradrenaline interactions with ryanodine receptors during memory formation in the young chick.

Impairment of nitric oxide (NO) production, ryanodine receptor (RyR) calcium channel function and adrenoceptor activation have been found to prevent the formation of the long-term memory stage in young chicks trained on a single-trial discrimination avoidance task. The current study investigated whether these three activities were linked, and if so, the sequence of activation. Young chicks were trained using either a strongly or weakly reinforced variant of the single-trial discrimination avoidance task, yielding either a persistent or labile memory trace, respectively. Following strongly reinforced training, retention loss induced by a RyR inhibitor was prevented by a NO donor or noradrenaline (NA). A RyR agonist also prevented retention loss induced by either NO synthase or β1+2-adrenoceptor inhibition. These findings were interpreted to reflect the capacity of NO, RyR-dependent calcium release and NA to modulate memory by preventing retention loss. A second set of studies used weakly reinforced training. Although the administration of a RyR agonist promoted long-term memory formation, this facilitation was compromised in the presence of a β1+2-adrenoceptor antagonist, but not a NO synthase inhibitor. Similarly, the inhibition of RyRs interfered with the facilitation of retention induced by a NO donor, but not NA. These differential findings with weakly reinforced training suggest that NO facilitates memory formation through mechanisms involving RyR-dependent calcium release. The findings also indicate that RyRs may promote memory formation through noradrenergic activation of β2-adrenoceptors. This study demonstrates an intricate role for RyRs underlying memory formation. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Accidental and deliberate microbiological contamination in the feed and food chains--how biotraceability may improve the response to bioterrorism

A next frontier of the global food safety agenda has to consider a broad spectrum of bio-risks, such as accidental and intentional contaminations in the food and feed chain. In this article, the background for the research needs related to biotraceability and response to bioterrorism incidents are outlined. Given the current scale of international trade any response need to be considered in an international context. Biotraceability (e.g. the ability to use downstream information to point to processes or within a particular food chain that can be identified as the source of undesirable agents) is crucial in any food-born outbreak and particular in the response to bioterrorism events. In the later case, tested and proven biotraceability improves the following: (i) international collaboration of validated tracing tools and detection methods, (ii) multi-disciplinary expertise and collaboration in the field of food microbiology and conceptual modeling of the food chain, (iii) sampling as a key step in biotracing (iv) optimized sample preparation procedures, including laboratory work in Biosafety level 3 (BSL-3) laboratories, (v) biomarker discovery for relevant tracing and tracking applications, and (vi) high-throughput sequencing using bio-informatic platforms to speed up the characterization of the biological agent. By applying biotraceability, the response phase during a bioterrorism event may be shortened and is facilitated for tracing the origin of biological agent contamination.     

Tannin levels in cassava,a comparison of methods of analysis

Low levels of tannins (proanthocyanidins) have been detected in dried cassava (Manihot esculenta Crantz) samples using standard methods of analysis based on extraction procedures. A direct vanillin assay method was compared with other direct methods of analysis based on acid hydrolysis and protein precipitation. The specificity of the methods is discussed in relation to the levels of tannins detected and their potential biological activity in freeze dried fresh and dried/processed cassava samples. The results are discussed with respect to the amount of indigestible material present in the samples. The results of these experiments indicate that tannins present in dried/processed cassava products may be a factor limiting their nutritional value.