71 research outputs found
Benchmark of FEM, Waveguide and FDTD Algorithms for Rigorous Mask Simulation
An extremely fast time-harmonic finite element solver developed for the
transmission analysis of photonic crystals was applied to mask simulation
problems. The applicability was proven by examining a set of typical problems
and by a benchmarking against two established methods (FDTD and a differential
method) and an analytical example. The new finite element approach was up to
100 times faster than the competing approaches for moderate target accuracies,
and it was the only method which allowed to reach high target accuracies.Comment: 12 pages, 8 figures (see original publication for images with a
better resolution
Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases
The production of peroxide and superoxide is an inevitable consequence of
aerobic metabolism, and while these particular "reactive oxygen species" (ROSs)
can exhibit a number of biological effects, they are not of themselves
excessively reactive and thus they are not especially damaging at physiological
concentrations. However, their reactions with poorly liganded iron species can
lead to the catalytic production of the very reactive and dangerous hydroxyl
radical, which is exceptionally damaging, and a major cause of chronic
inflammation. We review the considerable and wide-ranging evidence for the
involvement of this combination of (su)peroxide and poorly liganded iron in a
large number of physiological and indeed pathological processes and
inflammatory disorders, especially those involving the progressive degradation
of cellular and organismal performance. These diseases share a great many
similarities and thus might be considered to have a common cause (i.e.
iron-catalysed free radical and especially hydroxyl radical generation). The
studies reviewed include those focused on a series of cardiovascular, metabolic
and neurological diseases, where iron can be found at the sites of plaques and
lesions, as well as studies showing the significance of iron to aging and
longevity. The effective chelation of iron by natural or synthetic ligands is
thus of major physiological (and potentially therapeutic) importance. As
systems properties, we need to recognise that physiological observables have
multiple molecular causes, and studying them in isolation leads to inconsistent
patterns of apparent causality when it is the simultaneous combination of
multiple factors that is responsible. This explains, for instance, the
decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference
Uptake kinetics of the somatostatin receptor ligand (86Y)DOTA-DPhe1-Tyr3-octreotide ([86Y]SMT487) using positron emission tomography in non-human primates and calculation of radiation doses of the 90Y-labelled analogue
[[sup 90]Y]DOTA-DPhe[sup 1]-Tyr[sup 3]-octreotide ([[sup 90]Y]SMT487) has been suggested as a promising radiotherapeutic agent for somatostatin receptor-expressing tumours. In order to quantify the in vivo parameters of this compound and the radiation doses delivered to healthy organs, the analogue [[sup 86]Y]DOTA-DPhe[sup 1]-Tyr[sup 3]-octreotide was synthesised and its uptake measured in baboons using positron emission tomography (PET). [[sup 86]Y]DOTADPhe[sup 1]-Tyr[sup 3]-octreotide was administered at two different peptide concentrations, namely 2 and 100 micro g peptide per m2 body surface. The latter concentration corresponded to a radiotherapeutic dose. In a third protocol [[sup 86]Y]DOTA-DPhe[sup 1]-Tyr[sup 3]-octreotide was injected in conjunction with a simultaneous infusion of an amino acid solution that was high in L-lysine in order to lower the renal uptake of radioyttrium..
Validation of physical and 3D numerical modelling of hydrodynamic flow impacts on objects
Physics-Based Modeling of Electric Operation, Heat Transfer, and Scrap Melting in an AC Electric Arc Furnace
Electric arc furnaces (EAF) are complex industrial plants whose actual behavior depends upon numerous factors. Due to its energy intensive operation, the EAF process has always been subject to optimization efforts. For these reasons, several models have been proposed in literature to analyze and predict different modes of operation. Most of these models focused on the processes inside the vessel itself. The present paper introduces a dynamic, physics-based model of a complete EAF plant which consists of the four subsystems vessel, electric system, electrode regulation, and off-gas system. Furthermore the solid phase is not treated to be homogenous but a simple spatial discretization is employed. Hence it is possible to simulate the energy input by electric arcs and fossil fuel burners depending on the state of the melting progress. The model is implemented in object-oriented, equation-based language Modelica. The simulation results are compared to literature data
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