Design of corrugated optical waveguide filters through a direct numerical solution of the coupled Gel'fand-Levitan-Marchenko integral equations

Regarding the design problem of corrugated planar optical waveguide filters, a new numerical method is presented consisting of a direct numerical solution of the coupled Gel'fand-Levitan-Marchenko integral equations. This method, which uses leapfrogging in space and time, is exact in principle and avoids some difficulties encountered in previously derived analytical methods of solution. Straightforward numerical calculations permit the design of several classes of filters such as Butterworth, Chebyshev, Cauer (elliptic) and others, as presented in the paper. The accuracy of our proposed method of design is checked in several ways, mainly through the numerical solution of the corresponding direct-scattering problem (Riccati differential equation).     

Econazole-releasing porous space maintainers for fungal periprosthetic joint infection

While antibiotic-eluting polymethylmethacrylate space maintainers have shown efficacy in the treatment of bacterial periprosthetic joint infection and osteomyelitis, antifungal-eluting space maintainers are associated with greater limitations for treatment of fungal musculoskeletal infections including limited elution concentration and duration. In this study, we have designed a porous econazole-eluting space maintainer capable of greater inhibition of fungal growth than traditional solid space maintainers. The eluted econazole demonstrated bioactivity in a concentration-dependent manner against the most common species responsible for fungal periprosthetic joint infection as well as staphylococci. Lastly, these porous space maintainers retain compressive mechanical properties appropriate to maintain space before definitive repair of the joint or bony defect.

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The role of message-sequences in the sustainability of an online support community for older people

This article presents an investigation of an online support community for older people, analyzing a data-set of messages posted over the period of six years. We studied messages that are related to each other which we call "message-sequences". We investigated the content of message-sequences and linked our findings to the level of activity of the online support community over time. We show how certain sequences of messages within the online community are related to the level of activity thus providing valuable insight into the role of message-sequences in sustaining online support communities for older people. We conclude that the mutual exchange of personal information and receiving support after talking about personal problems are basic components for the sustainability of the online community, whereas conversations that go off the topic of the online community seem to be related to a decrease in the level of activity.     

Effects of varying levels of dietary free gossypol in whole cotton seed on physiological responses of growing–fattening lambs

Effects of increasing concentrations of free gossypol in diets containing up to 30% whole cottonseed on blood metabolites were studied using 32 Karagouniko male lambs in a 4 × 3 factorial arrangement with treatments of four whole cottonseed levels and three times of sampling. The diets used were isocaloric (12.5–13.1 MJ metabolisable energy kg⁻¹ dry matter) with 163–186 g crude protein kg⁻¹ dry matter containing 0%, 5–10%, 10–20% and 15–30% whole cottonseed and were fed ad libitum for 54 days. Blood samples were taken at the beginning, middle and end of the experiment. The blood parameters examined were: haematocrit, haemoglobin, mean corpuscular haemoglobin concentration, erythrocyte sedimentation rate, plasma glucose, urea, total protein, albumin and globulin concentrations and serum total and free cholesterol, cholesterol esters and inorganic K concentrations. In addition, the serum enzyme activities of glutamate pyruvate transaminase, γ-glutamyl transpeptidase and lactate dehydrogenase, as indicative of liver and heart muscle damage, and the concentrations of the major elements Ca, Mg and K and also of the trace elements Fe, Cu and Zn in liver, kidneys and heart of slaughtered lambs were estimated. This study was also made to determine the effect of whole cottonseed diets on the accumulation of free gossypol in some organs of growing lambs. Most of the blood components evaluated were affected by the diet fed. Blood haematocrit and erythrocyte sedimentation rate were higher at the beginning of the experiment, but haemoglobin and mean corpuscular haemoglobin concentrations were higher at day 28 of the experimental period; plasma total protein, urea, albumin and globulin concentrations and also serum total and free cholesterol and inorganic K concentrations were higher at day 54 of the experiment. The serum enzyme activities of glutamate pyruvate transaminase, γ-glutamyl transpeptidase and lactate dehydrogenase were all higher at day 54 of the experimental period. However, there were significant differences between treatments and between times of sampling in the three enzyme activities measured. Liver, kidneys and heart examination showed significant differences for all organs in NPN, fat, fat/protein ratio and the major elements Ca, Mg and K among the four treatments. However, of the trace elements examined, differences were significant for Fe in liver, Cu in heart and Zn in liver and heart. The greatest free gossypol accumulation was observed, as expected, in liver, followed by kidneys and lastly by heart. There was an indication of possible gossypol toxicity in these growing lambs as a result of the marked elevations of the activity of lactate dehydrogenase and possibly of the increase in plasma urea concentration. © 1999 Society of Chemical Industry     

Structural analysis and design against failure of fusion power plant components with special reference to pulsed operation

This study presents the theory of structural analysis and design code rules and constraints as applied to predict lifetime and prevent failure of components and is tailored to deal with the specific design requirements of fusion components. Example calculations are performed for a proposed ITER-like first wall using finite element analysis codes and an assessment of the structural behaviour is also included. The results of the calculations are used to arrive at a proposed design methodology, which accounts for the structural mechanisms likely to occur when operating a tokamak in pulsed mode, as proposed for ITER.     

A Practical Approach to Energy Efficient Communications in Mobile Wireless Networks

Energy efficiency and capacity maximization are two of the most challenging issues to be addressed by current and future cellular networks. Significant research effort has been placed recently in reducing the total energy consumption while maintaining or improving capacity either by introducing more efficient hardware components or by developing innovative software techniques. In this paper we investigate a novel networking paradigm to address the aforementioned problems. By capitalizing on the inherent delay tolerance of Internet type services, we argue that significant energy savings can be achieved by postponing the communication of information for a later time instance with better networking conditions. We device decentralized algorithms for the proposed postponement schemes and show the superior performance of implementing such schemes over the traditional cellular operation.     

Evaluation of visual feedback techniques for virtual grasping with bare hands using Leap Motion and Oculus Rift

Virtual Reality - Bare hand interaction (BHI) allows users to use their hands and fingers to interact with digital content without any attached devices or accessories. For BHI to realize widespread...     

Operationalizing sustainability in urban coastal systems: A system dynamics analysis

We propose a system dynamics approach for Ecologically Sustainable Development (ESD) in urban coastal systems. A systematic analysis based on theoretical considerations, policy analysis and experts' knowledge is followed in order to define the concept of ESD. The principles underlying ESD feed the development of a System Dynamics Model (SDM) that connects the pollutant loads produced by urban systems' socioeconomic activities with the ecological condition of the coastal ecosystem that it is delineated in operational terms through key biological elements defined by the EU Water Framework Directive. The receiving waters of the Athens Metropolitan area, which bears the elements of typical high population density Mediterranean coastal city but which currently has also new dynamics induced by the ongoing financial crisis, are used as an experimental system for testing a system dynamics approach to apply the concept of ESD. Systems' thinking is employed to represent the complex relationships among the components of the system. Interconnections and dependencies that determine the potentials for achieving ESD are revealed. The proposed system dynamics analysis can facilitate decision makers to define paths of development that comply with the principles of ESD.