2,283 research outputs found

    Scenic and Recreational River Designation: What Happened to the James?

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    In 1976, the South Dakota Department of Game , Fish and Parks (DGFP) sponsored the nomination of the upper James River as a state scenic and recreational river. The nomination failed to receive legislative approval in the 1977 and 1978 state legislative sessions. A case analysis of this nomination and the failure to approve it is provided in this publication. The major participants are identified, and their �· relationships with each other and how they fared are examined. This gives an understanding of why and how the actors react to the rules in a water allocation process and an overview of the designation process. The case study also provides a historical perspective on one designation process, serving as a basis for future public considerations of changes in the river designation process

    Antireflective nanotextures for monolithic perovskite silicon tandem solar cells

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    Recently, we studied the effect of hexagonal sinusoidal textures on the reflective properties of perovskite silicon tandem solar cells using the finite element method FEM . We saw that such nanotextures, applied to the perovskite top cell, can strongly increase the current density utilization from 91 for the optimized planar reference to 98 for the best nanotextured device period 500 nm and peak to valley height 500 nm , where 100 refers to the Tiedje Yablonovitch limit. [D. Chen et al., J. Photonics Energy 8, 022601, 2018 , doi 10.1117 1.JPE.8.022601] In this manuscript we elaborate on some numerical details of that work we validate an assumption based on the Tiedje Yablonovitch limit, we present a convergence study for simulations with the finite element method, and we compare different configurations for sinusoidal nanotexture

    Gordon Valentine Manley and his contribution to the study of climate change: a review of his life and work

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    British climatologist and geographer, Gordon Manley (1902–1980), is perhaps best known for his pioneering work on climate variability in the UK, for establishing the Central England Temperature series and, for his pivotal role in demonstrating the powerful relationship between climate, weather, and culture in post-World War II Britain. Yet Manley made many contributions, both professional and popular, to climate change debates in the twentieth century, where climate change is broadly understood to be changes over a range of temporal and spatial scales rather than anthropogenic warming per se. This review first establishes how Manley's work, including that on snow and ice, was influenced by key figures in debates over climatic amelioration around the North Atlantic between 1920s and 1950s. His research exploring historical climate variability in the UK using documentary sources is then discussed. His perspectives on the relationship between climate changes and cultural history are reviewed, paying particular attention to his interpretation of this relationship as it played out in the UK. Throughout, the review aims to show Manley to be a fieldworker and an empiricist and reveals how he remained committed to rigorous scientific investigation despite changing trends within his academic discipline

    Improving Monolithic Perovskite Silicon Tandem Solar Cells From an Optical Viewpoint

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    Perovskite silicon tandem solar cells are the most promising concept for a future photovoltaic technology. We report on recent progress from an optical viewpoint and disucss how we achieved more than 25 device efficienc

    Length scale dependence of dynamical heterogeneity in a colloidal fractal gel

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    We use time-resolved dynamic light scattering to investigate the slow dynamics of a colloidal gel. The final decay of the average intensity autocorrelation function is well described by g_2(q,τ)1exp[(τ/τ_f)p]g\_2(q,\tau)-1 \sim \exp[-(\tau/\tau\_\mathrm{f})^p], with τ_fq1\tau\_\mathrm{f} \sim q^{-1} and pp decreasing from 1.5 to 1 with increasing qq. We show that the dynamics is not due to a continuous ballistic process, as proposed in previous works, but rather to rare, intermittent rearrangements. We quantify the dynamical fluctuations resulting from intermittency by means of the variance χ(τ,q)\chi(\tau,q) of the instantaneous autocorrelation function, the analogous of the dynamical susceptibility χ_4\chi\_4 studied in glass formers. The amplitude of χ\chi is found to grow linearly with qq. We propose a simple --yet general-- model of intermittent dynamics that accounts for the qq dependence of both the average correlation functions and χ\chi.Comment: Revised and improved, to appear in Europhys. Let

    Mechanism of Pion Production in alphaalphap Scattering at 1 GeV/nucleon

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    The one-pion and two-pion production in the p(alpha, alpha prime)X reaction at an energy of E{alpha} = 4.2 GeV has been studied by simultaneous registration of the scattered alpha particles and the secondary pion or proton. The obtained results demonstrate that the inelastic alpha-particle scattering on the proton at the energy of the experiment proceeds either through excitation and decay of Delta resonance in the projectile or through excitation in the target proton of the Roper resonance, which decays mainly on a nucleon and a pion or a nucleon and a sigma meson - system of two pions in the isospin I = 0, S-wave.Comment: 16 pages, 10 figures. Submitted to Proceedings of the XX International Baldin Seminar on High - Energy Physics Problems, Dubna, October 4 - 9, 201

    How can field margin management contribute to invertebrate biodiversity?

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    Farmland invertebrates are vital for healthy ecosystem functioning. Many groups have declined due to agricultural intensification. Arable field margins potentially can increase food resources and provide winter refuges for invertebrates. They might also buffer them from agrochemical applications and farm operations. This chapter describes a series of field and farm-scale experiments which show that ways in which arable field margins are established and managed can have profound effects on their invertebrate assemblages. Field margin swards established by sowing with a grass and wildflower seed mixture attracted more butterflies than naturally regenerated swards. In the short term, larger and more species-rich invertebrate assemblages were fostered on unmanaged margins than on those managed by cutting. The timing of cutting was critical, with mid-summer cutting having the most persistent, negative effects on invertebrates, while cutting in spring and autumn was generally less damaging and may help maintain sward species richness. Fallowed land (set-aside) configured as blocks rather than margins constituted qualitatively different habitats for invertebrates. Margin width had complex effects on invertebrate abundance and species richness. Boundary hedgerows increased numbers of most invertebrate groups in the adjacent margin. The chapter suggests that blanket management approaches for invertebrates at the farm scale are not optimal. A diverse farmed landscape, with margins of different sizes and different sward structures, will provide for the different ecological requirements of invertebrate populations, and promote their diversity in the characteristically unstable environment of arable systems
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