40,842 research outputs found

    SUSMETRO : Impact Assessment Tools for Food Planning in Metropolitan Regions : IA tools and serious gaming in support of sustainability targets for food planning, nature conservation and recreation

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    By offering a series of decision support tools for stakeholders of metropolitan regions, SUSMETRO facilitates and enables evidence-based decision making by means of ‘serious gaming’. Making use of the Phase 1 thematic maps such as on agricultural competitiveness, nature conservation and recreational values, stakeholders can compare impacts of traditional versus innovative forms of agricultural production. The SUSMETRO Impact Assessment tool provides information on the expected effects of spatial planning with regard to the self-supportive capacities of the region (ecological footprint) and the share of recreational and nature conservation facilities (land use functions), offering cost-benefit calculations regarding the expected economic revenues. The whole process is embedded in a Landscape Character Assessment process and guided by Knowledge Brokerage procedures to strengthen the science-policy interface. In sum, the SUSMETRO approach allows a wide range of stakeholders to co-develop images for sustainable Metropolitan Agriculture

    Long-Distance Wind-Dispersal of Spores in a Fungal Plant Pathogen: Estimation of Anisotropic Dispersal Kernels from an Extensive Field Experiment

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    Given its biological significance, determining the dispersal kernel (i.e., the distribution of dispersal distances) of spore-producing pathogens is essential. Here, we report two field experiments designed to measure disease gradients caused by sexually- and asexually-produced spores of the wind-dispersed banana plant fungus Mycosphaerella fijiensis. Gradients were measured during a single generation and over 272 traps installed up to 1000 m along eight directions radiating from a traceable source of inoculum composed of fungicide-resistant strains. We adjusted several kernels differing in the shape of their tail and tested for two types of anisotropy. Contrasting dispersal kernels were observed between the two types of spores. For sexual spores (ascospores), we characterized both a steep gradient in the first few metres in all directions and rare long-distance dispersal (LDD) events up to 1000 m from the source in two directions. A heavy-tailed kernel best fitted the disease gradient. Although ascospores distributed evenly in all directions, average dispersal distance was greater in two different directions without obvious correlation with wind patterns. For asexual spores (conidia), few dispersal events occurred outside of the source plot. A gradient up to 12.5 m from the source was observed in one direction only. Accordingly, a thin-tailed kernel best fitted the disease gradient, and anisotropy in both density and distance was correlated with averaged daily wind gust. We discuss the validity of our results as well as their implications in terms of disease diffusion and management strategy

    Boson-fermion mappings for odd systems from supercoherent states

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    We extend the formalism whereby boson mappings can be derived from generalized coherent states to boson-fermion mappings for systems with an odd number of fermions. This is accomplished by constructing supercoherent states in terms of both complex and Grassmann variables. In addition to a known mapping for the full so(2NN+1) algebra, we also uncover some other formal mappings, together with mappings relevant to collective subspaces.Comment: 40 pages, REVTE

    Quantitative MRFM characterization of the autonomous and forced dynamics in a spin transfer nano-oscillator

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    Using a magnetic resonance force microscope (MRFM), the power emitted by a spin transfer nano-oscillator consisting of a normally magnetized Py|Cu|Py circular nanopillar is measured both in the autonomous and forced regimes. From the power behavior in the subcritical region of the autonomous dynamics, one obtains a quantitative measurement of the threshold current and of the noise level. Their field dependence directly yields both the spin torque efficiency acting on the thin layer and the nature of the mode which first auto-oscillates: the lowest energy, spatially most uniform spin-wave mode. From the MRFM behavior in the forced dynamics, it is then demonstrated that in order to phase-lock this auto-oscillating mode, the external source must have the same spatial symmetry as the mode profile, i.e., a uniform microwave field must be used rather than a microwave current flowing through the nanopillar

    Densely integrated microring resonator based photonic devices for use in access networks

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    Two reconfigurable optical add-drop multiplexers, operating in the second or third telecom window, as well as a 1x4x4 reconfigurable λ-router operating in the second telecom window, are demonstrated. The devices have a footprint less than 2 mm2 and are based on thermally tunable vertically coupled microring resonators fabricated in Si3N4/SiO2

    Circulating markers of arterial thrombosis and late-stage age-related macular degeneration: a case-control study.

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    PURPOSE: The aim of this study was to examine the relation of late-stage age-related macular degeneration (AMD) with markers of systemic atherothrombosis. METHODS: A hospital-based case-control study of AMD was undertaken in London, UK. Cases of AMD (n=81) and controls (n=77) were group matched for age and sex. Standard protocols were used for colour fundus photography and to classify AMD; physical examination included height, weight, history of or treatment for vascular-related diseases and smoking status. Blood samples were taken for measurement of fibrinogen, factor VIIc (FVIIc), factor VIIIc, prothrombin fragment F1.2 (F1.2), tissue plasminogen activator, and von Willebrand factor. Odds ratios from logistic regression analyses of each atherothrombotic marker with AMD were adjusted for age, sex, and established cardiovascular disease risk factors, including smoking, blood pressure, body mass index, and total cholesterol. RESULTS: After adjustment FVIIc and possibly F1.2 were inversely associated with the risk of AMD; per 1 standard deviation increase in these markers the odds ratio were, respectively, 0.62 (95% confidence interval 0.40, 0.95) and 0.71 (0.46, 1.09). None of the other atherothrombotic risk factors appeared to be related to AMD status. There was weak evidence that aspirin is associated with a lower risk of AMD. CONCLUSIONS: This study does not provide strong evidence of associations between AMD and systematic markers of arterial thrombosis, but the potential effects of FVIIc, and F1.2 are worthy of further investigation

    Microscopic Conductivity of Lattice Fermions at Equilibrium - Part I: Non-Interacting Particles

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    We consider free lattice fermions subjected to a static bounded potential and a time- and space-dependent electric field. For any bounded convex region RRd\mathcal{R}\subset \mathbb{R}^{d} (d1d\geq 1) of space, electric fields E\mathcal{E} within R\mathcal{R} drive currents. At leading order, uniformly with respect to the volume R\left| \mathcal{R}\right| of R\mathcal{R} and the particular choice of the static potential, the dependency on E\mathcal{E} of the current is linear and described by a conductivity distribution. Because of the positivity of the heat production, the real part of its Fourier transform is a positive measure, named here (microscopic) conductivity measure of R\mathcal{R}, in accordance with Ohm's law in Fourier space. This finite measure is the Fourier transform of a time-correlation function of current fluctuations, i.e., the conductivity distribution satisfies Green-Kubo relations. We additionally show that this measure can also be seen as the boundary value of the Laplace-Fourier transform of a so-called quantum current viscosity. The real and imaginary parts of conductivity distributions satisfy Kramers-Kronig relations. At leading order, uniformly with respect to parameters, the heat production is the classical work performed by electric fields on the system in presence of currents. The conductivity measure is uniformly bounded with respect to parameters of the system and it is never the trivial measure 0dν0\,\mathrm{d}\nu . Therefore, electric fields generally produce heat in such systems. In fact, the conductivity measure defines a quadratic form in the space of Schwartz functions, the Legendre-Fenchel transform of which describes the resistivity of the system. This leads to Joule's law, i.e., the heat produced by currents is proportional to the resistivity and the square of currents
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