981 research outputs found

    Conditions for waveguide decoupling in square-lattice photonic crystals

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    We study coupling and decoupling of parallel waveguides in two-dimensional square-lattice photonic crystals. We show that the waveguide coupling is prohibited at some wavelengths when there is an odd number of rows between the waveguides. In contrast, decoupling does not take place when there is even number of rows between the waveguides. Decoupling can be used to avoid cross talk between adjacent waveguides.Comment: 6 pages, 2 figure

    Validation of Nonlinear Bipolar Transistor Model by Small-Signal Measurements

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    Methane dynamics in different boreal lake types

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    This study explores the variability in concentrations of dissolved CH<sub>4</sub> and annual flux estimates in the pelagic zone in a statistically defined sample of 207 lakes in Finland. The lakes were situated in the boreal zone, in an area where the mean annual air temperature ranges from −2.8 to 5.9°C. We examined how lake CH<sub>4</sub> dynamics related to regional lake types assessed according to the EU water framework directive. Ten lake types were defined on the basis of water chemistry, color, and size. Lakes were sampled for dissolved CH<sub>4</sub> concentrations four times per year, at four different depths at the deepest point of each lake. We found that CH<sub>4</sub> concentrations and fluxes to the atmosphere tended to be high in nutrient rich calcareous lakes, and that the shallow lakes had the greatest surface water concentrations. Methane concentration in the hypolimnion was related to oxygen and nutrient concentrations, and to lake depth or lake area. The surface water CH<sub>4</sub> concentration was related to the depth or area of lake. Methane concentration close to the bottom can be viewed as proxy of lake status in terms of frequency of anoxia and nutrient levels. The mean pelagic CH<sub>4</sub> release from randomly selected lakes was 49 mmol m<sup>−2</sup> a<sup>−1</sup>. The sum CH<sub>4</sub> flux (storage and diffusion) correlated with lake depth, area and nutrient content, and CH<sub>4</sub> release was greatest from the shallow nutrient rich and humic lakes. Our results support earlier lake studies regarding the regulating factors and also the magnitude of global emission estimate. These results propose that in boreal region small lakes have higher CH<sub>4</sub> fluxes per unit area than larger lakes, and that the small lakes have a disproportionate significance regarding to the CH<sub>4</sub> release

    Erosion-oxidation of pressure vessel steel P265GH

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    The behaviour of pressure vessel steel P265GH was studied in a centrifugal high-temperature erosion apparatus under impacts by silica (SiO2) particles moving at velocities ranging from 20 to 60 m s-1 and contacting the surface at the angles of 30° and 90°. Besides particle impacts, the steel was simultaneously exposed to air and elevated temperatures of 350 and 450°C. For comparison, the tests were also performed in the absence of erodent particles. After the tests, the material behaviour was evaluated in terms of occurred weight changes and surface characteristics, the latter ones of which were investigated by using, for example, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). In the analysis of the test results, special attention was paid to the composition and microstructure of the used silica particles and how these influence the elemental distribution on the exposed surfaces. The results show that the particle impacts introduce weight losses that follow a ductile angle-dependency, i.e., relatively greater weight losses at the shallow than at the steep impact angle. Although evident oxide scales developed on the surfaces at the test temperatures, they did not provide the steel with protection against particle impacts. Particle debris was detected embedded in the surfaces particularly under impacts at 90°, with softer particle constituents being preferentially deposited. These results are discussed in terms of the erosion-oxidation behaviour of the steel and the consequences of the heterogeneous erodent particle quality

    An integrated hardware/software design methodology for signal processing systems

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    This paper presents a new methodology for design and implementation of signal processing systems on system-on-chip (SoC) platforms. The methodology is centered on the use of lightweight application programming interfaces for applying principles of dataflow design at different layers of abstraction. The development processes integrated in our approach are software implementation, hardware implementation, hardware-software co-design, and optimized application mapping. The proposed methodology facilitates development and integration of signal processing hardware and software modules that involve heterogeneous programming languages and platforms. As a demonstration of the proposed design framework, we present a dataflow-based deep neural network (DNN) implementation for vehicle classification that is streamlined for real-time operation on embedded SoC devices. Using the proposed methodology, we apply and integrate a variety of dataflow graph optimizations that are important for efficient mapping of the DNN system into a resource constrained implementation that involves cooperating multicore CPUs and field-programmable gate array subsystems. Through experiments, we demonstrate the flexibility and effectiveness with which different design transformations can be applied and integrated across multiple scales of the targeted computing system

    Long-term clinical and economic outcomes in previously untreated paediatric patients with severe haemophilia A : A nationwide real-world study with 700 person-years

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    AimFor previously untreated patients (PUPs) with severe haemophilia A in Finland for the past 2 decades, the standard practice has been to start early primary prophylaxis. We evaluated the long-term clinical outcomes and costs of treatment with high-dose prophylaxis in PUPs from birth to adolescence, including immune tolerance induction (ITI). MethodsFrom the medical records of all PUPs born between June 1994 and May 2013 in Finland, we retrospectively extracted data on clinical outcomes and healthcare use. Using linear mixed models, we analysed longitudinal clinical outcome data. To analyse skewed cost data, including zero costs, we applied hurdle regression. ResultsAll 62 patients received early regular prophylaxis; totally, they have had treatment for nearly 700 patient-years. The median age of starting home treatment was 1.1years. The mean (SD) annual treatment costs (Europerkg) were 4391Euro (3852). For ages 1-3, ITI comprised over half of the costs; in other groups, prophylactic FVIII treatment dominated. With these high costs, however, clinical outcomes were desirable; median (IQR) ABR was low at 0.19 (0.07-0.46) and so was AJBR at 0.06 (0-0.24). Thirteen (21%) patients developed a clinically significant inhibitor, 10 (16%) with a high titre. All ITIs were successful. The mean costs for ITI were 383448Euro (259085). The expected ITI payback period was 1.81 (95% CI 0.62-12.12) years. ConclusionsEarly high-dose prophylaxis leads to excellent long-term clinical outcomes, and early childhood ITI therapy seems to turn cost-neutral generally already in 2years.Peer reviewe
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