9,144 research outputs found

    Benchmark of FEM, Waveguide and FDTD Algorithms for Rigorous Mask Simulation

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    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

    EFFECT OF RECREATIONAL TRAIL TRAFFIC LEVEL ON EASTERN RED-BACKED SALAMANDER (PLETHODON CINEREUS) RELATIVE ABUNDANCE

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    The effects of roads and trails on terrestrial salamanders, primarily plethodontids, can be important. The abundance of terrestrial salamanders often increases with distance from roads. Less is known about the effects of recreational or hiking trails on terrestrial salamanders than is known about the effects of roads. We explored how low and high traffic trails in a suburban biological reserve affect the relative abundance of Eastern Red-backed Salamanders (Plethodon cinereus). We found more salamanders under cover objects next to low traffic trails compared to either high traffic trails or wooded areas without trails. At wooded sites, we found only striped morphs whereas at high traffic sites we found only unstriped morphs. Low traffic sites included a range of color morph frequencies. The proportion of females found in each site did not differ, nor did the mean size of the salamanders. Our results suggest that the impact of recreational walking trails needs to be examined more closely to see how and why the distributions of P. cinereus, and potentially other woodland salamanders, are affected and what trail characteristics are important in driving the apparent effects. Such information will contribute to the design and maintenance of walking trails in natural areas that minimize effects on terrestrial salamanders, and likely other organisms

    Relative Invertebrate Abundance and Biomass in Conservation Reserve Program Plantings in Northern Missouri

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    We measured relative invertebrate abundance, biomass, and diversity in Conservation Reserve Program (CRP) fields planted to red clover (Trifolium pratense)/timothy (Phleum pratense), timothy, orchard-grass (Dactylis glomerata), tall fescue (Festuca pratensis), warm-season grasses (big bluestem [Andropogon gerardi]/switch grass [Panicum virgatum]), orchard-grass/Korean lespedeza (Kummerowia stipu/,acea), and conventionally-tilled soybeans, to assess brood habitat quality for northern bobwhite (Colinus virginkinus). We sampled invertebrate populations by vacuuming along 3 15-m transects (4.56 m2/sample) within 4 fields of each planting type, at 2-week intervals from 1 July to 15 August 1990 and 1991. Invertebrate abundance and biomass were lowest in early August (P \u3c 0.05). The CRP fields planted to a red clover/timothy mixture, and dominated by red clover, had the highest levels of invertebrate abundance and biomass (P \u3c 0.05). Conventionally-tilled soybeans had lower invertebrate abundance and biomass than all CRP covertypes (P\u3c 0.05). Mean invertebrate abundance and biomass in CRP fields were 4 times that of soybean fields. In northern Missouri, CRP fields could provide quality brood habitat if structural characteristics are also consistent with brood foraging needs. Incorporation of a legume in CRP plantings may produce higher invertebrate densities and improve the value of these fields as brood habitat

    Elastic-Net Regularization: Error estimates and Active Set Methods

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    This paper investigates theoretical properties and efficient numerical algorithms for the so-called elastic-net regularization originating from statistics, which enforces simultaneously l^1 and l^2 regularization. The stability of the minimizer and its consistency are studied, and convergence rates for both a priori and a posteriori parameter choice rules are established. Two iterative numerical algorithms of active set type are proposed, and their convergence properties are discussed. Numerical results are presented to illustrate the features of the functional and algorithms

    The effect of crustal structure on strong ground motion attenuation relations in eastern North America

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    Strong ground motion attenuation relations are usually described by smoothly decreasing functions of distance. However, consideration of wave propagation in the crust suggests that attenuation relations should be more complex. Such complexity may be present in strong ground motion data for eastern North American earthquakes, which show amplitudes in the distance range of 60 to 150 km that lie above the trends at smaller and greater distances. Using a wavenumber integration method to compute Green's functions and close-in recordings of several earthquakes as empirical source functions, we have generated synthetic seismograms that are in good agreement with regional and strong-motion recordings of eastern North American earthquakes. From these synthetic seismograms, we have shown that the observed interval of relatively high amplitudes may be attributable to postcritically reflected S waves from the Moho. The presence and location of the interval of relatively high amplitudes is highly dependent on the crustal velocity structure and may therefore be expected to show regional variation. However, for any realistic structure model, there will be a transition in the attenuation relation from an interval at shorter distances (less than about 100 km) that is dominated by direct waves to an interval at greater distances that is dominated by postcritically reflected waves. The synthetic seismograms have response spectral velocities that match those of the recorded data, and their m_(bLg) values are in good agreement with observed values

    High-Speed Coating of Primer Layer for Li-Ion Battery Electrodes by Using Slot-Die Coating

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    A reduction of the inactive components can increase the energy density and reduce production cost of Li‐ion batteries. But an effective reduction of the binder amount also negatively affects the adhesion of the electrode. Herein, slot‐die coating of a primer layer for Li‐ion anodes is investigated. It is shown that the use of a primer layer with only 0.3 g m−2^{-2} can increase the adhesive force by the factor of 5 as well as the cell performance for anodes with low binder content. The process limits for a stable, defect‐free primer coating are investigated at coating speeds of up to 550 m min−1^{-1}. The limits coincide both for a setup without vacuum box and with vacuum box with theory‐based equations. By using a vacuum box, the minimum wet film thickness can be reduced by half

    Viscosity Is Not a Parameter of Postdeglutitive Pharyngeal Residue: Quantification and Analysis with Scintigraphy

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    The aim of this study was to explore the influence of viscosity on pharyngeal residue in normal healthy volunteers. Scintigraphy was used to measure pharyngeal residue in 11 healthy volunteers after swallowing three different substances (age = 20.2–48.3 years). The first substance was a 10-ml solution of tap water with 0.5% xanthan with a viscosity of 4500 mPa s, comparable to a yogurt drink. The second and third substances were a 0.75% xanthan and a 1.00% xanthan solution, with viscosities of 10,500 and 21,000 mPa s, comparable to low-fat yogurt and 3% fat yogurt, respectively. Tap water was used as the control substance. Mean pharyngeal residue after swallowing tap water was 2.3% (SD = 1.2) of the initial volume in the oral cavity. Pharyngeal residue after swallowing 0.5% xanthan solution was 1.8% (SD = 0.8), after swallowing 0.75% xanthan solution 2.6% (SD = 2.2), and after swallowing 1.00% xanthan solution 2.8% (SD = 1.7). No significant correlation between increase of viscosity and pharyngeal residue was found. In healthy persons viscosity does not seem to be a significant parameter for pharyngeal residue for boluses with viscosities ranging from tap water to solutions having a viscosity comparable to 3% fat yogurt

    Phase engineering of controlled entangled number states in a single component Bose-Einstein condensate in a double well

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    We propose a model for the creation of entangled number states (Schr\"odinger cat states) of a Bose-Einstein condensate in a double well through simple phase engineering. We show that a π\pi-phase imprinted condensate in a double-well evolves, with a simultaneous change of barrier height, to number states with well defined and controlled entanglement. The cat state generation is understood in terms of the underlying classical phase space dynamics of a π\pi-phase displaced coherent state put at the hyperbolic fixed point of the separatrix of a physical pendulum. The extremity and sharpness of the final cat state is determined by the initial barrier height and the rate at which it is ramped during the evolution.Comment: 11 pages, 5 figures, Submitted to J. Phys. B (letter to the editor
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