2,935 research outputs found

    Organic farming and agri-environmental stewardship schemes in Devon

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    A postal survey was undertaken in North Devon looking at entry into England Rural Development Programme (ERDP) environmental schemes in relation to farming system and markets. The main survey was based in and around the North Devon Biosphere reserve. Significantly more farms replied who had Countryside Stewardship (CSS) agreements than from those who were not in the scheme. There was a greater likelihood of small farms joining CSS as were beef, sheep and cereal farms compared with dairy farms. A greater percent of organic farms had CSS agreements compared with the conventional farms. A smaller telephone survey in a CSS target area in South Devon was also undertaken which confirmed these results. Those farms with CSS agreements were more likely to have joined or be joining the new agri-environmental schemes

    Experimental and Theoretical Basis for a Closed-Form Spectral BRDF Model

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    The microfacet class of BRDF models is frequently used to calculate optical scatter from realistic surfaces using geometric optics, but has the disadvantage of not being able to consider wavelength dependence. This dissertation works toward development of a closed-form approximation to the BRDF that is suitable for hyperspectral remote sensing by presenting measured BRDF data of 12 different materials at four different incident angles and up to seven different wavelengths between 3.39 and 10.6 micrometer. The data was intended to be fit to various microfacet BRDF models to determine an appropriate form of the wavelength scaling. However, when fitting the microfacet models to measured data, the results indicated a breakdown in the microfacet model itself. To overcome this deficiency, elements of microfacet BRDF models are compared to elements of scalar wave optics BRDF models, which inherently contain a wavelength dependence. This analysis led to a theoretical understanding of how to modify microfacet BRDF models to maintain the simplicity of a closed-form model, while better approximating the underlying physics

    Erewhon' by Samuel Butler

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    Fictional aeolian devices in the novel Erewhon by Samuel Butle

    Inverse Scattering Transform Method for Lattice Equations

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    The main original contribution of this thesis is the development of a fully discrete inverse scattering transform (IST) method for nonlinear partial difference equations. The equations we solve are nonlinear partial difference equations on a quad-graph, also called lattice equations, which are known to be multidimensionally consistent in N dimensions for arbitrary N. Such equations were discovered by Nijhoff, Quispel and Capel and Adler and later classified by Adler, Bobenko and Suris. The main equation solved by our IST framework is the Q3δ lattice equation. Our approach also solves all of its limiting cases, including H1, known as the lattice potential KdV equation. Our results provide the discrete analogue of the solution of the initial value problem on the real line. We provide a rigorous justification that solves the problem for wide classes of initial data given along initial paths in a multidimensional lattice. Moreover, we show how soliton solutions arise from the IST method and also utilise asymptotics of the eigenfunctions to construct infinitely many conservation laws

    Effects of Crude Oil on Aquatic Insects of Tundra Ponds

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    Aquatic insects are numerous and important in the ecology of tundra thaw ponds, comprising most of the biomass and production. The most common types are the caddisflies Asynarchus and Micrasema, the stonefly Nemoura, the beetle Agabus and especially larvae of the fly family Chironomidae. Studies in vitro showed no detectable mortality of these insects at doses of oil up to 1.5 l/m² Prudhoe Bay crude oil. However, field experiments on two ponds with application rates of about 10 l/m² (Pond E, 1970) and 0.24 l/m² (Pond Omega, 1975) both indicated that selective elimination of Asynarchus and Nemoura had occurred. Chironomidae in Pond Omega displayed much lower rates of adult emergence in 1976 and 1977 than in 1975, immediately before and after oil treatment, with several species in the tribe Tanytarsini most reduced. Pond E did not show low emergence rates, but the proportion of Orthocladiinae was much higher than in reference ponds. Trichotanypus was severely reduced in Pond Omega but unusually abundant in Pond E in 1976 and 1977. Effects of oil seem to be different for different species, and occur at some point during the late larval stages of insects or at metamorphosis, but toxicity experiments did not confirm this. Oil may also interfere with reproduction in insect species which remain mainly on or near the pond surface as adults. Apparent effects in field experiments are not entirely consistent with observations of Canadian researchers. Nevertheless there were several similarities and both followed patterns like those observed in marine benthic communities, such as greater effects on shore fauna, greater effects of low-molecular-weight hydrocarbons, and species-specificity of effects. There is no indication of recovery of Nemoura, Asynarchus or Tanytarsini in Pond E seven years after the spill, but biomass and abundance of the other aquatic insects remains high. We recommend that clean-up measures avoid introducing solvents or dispersants, which might be toxic to insects in the pond

    The Legacy of Fascism

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66528/2/10.1177_001041407200500102.pd

    Equilibrium shapes of two and three dimensional two-phase rotating fluid drops with surface tension: effects of inner drop displacement

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    NSERCPeer ReviewedThe shapes of rotating fluid drops held together by surface tension is an important field of study in fluid mechanics. Recently, experiments with micron-scale droplets of liquid helium have been undertaken and it has proven useful to compare the shapes of the resultant superfluid droplets with classical analogs. If the helium is a mixture of He3 and He4, two phases are present. In a recent paper, the shapes of rotating two phase fluid droplets were calculated where the inner drop was constrained to stay at the drop center. The outer shapes and dimensionless rotation rate-angular momentum relationships were shown to be similar to single phase drops provided that the density and surface tension scales were chosen appropriately. In the current paper, I investigate models in which the inner drop can displace from the centre. In order to simplify the analyses, two dimensional drops are first investigated. I show that the inner drop is unstable in the centre position if its density is greater than the outer density and that the inner drop will move towards the outer boundary of the drop in these cases. When the inner drop has a higher density than the outer drop, the moment of inertia of displaced inner drops is increased relative to centered drops and hence the kinetic energy is decreased. Shapes of two and three dimensional drops, rotation rate-angular momentum and kinetic and surface energy relationships are investigated for off-axis inner drops with parameters relevant to recent liquid He experiments
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