2,222 research outputs found

    A Systems Approach to Assessing the Viability of Grazing Legume Systems Across Europe

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    Forage legumes are important in grassland farming throughout much of the world because of their ability to fix atmospheric nitrogen, and hence they are expected to play an increasingly prominent role in low- input grazing farming systems in Europe. Nevertheless, the socio-economic impact of the adoption of the new legume based grazing technologies have been poorly researched (Rochon et al., 2004). Thus a methodology has been developed to: * Assess the on-farm costs and benefits of including different legume crops for animal production;* Determine the types of management systems and environmental conditions under which forage legumes may play a major part as grazing crops in production systems in Europe;* and Determine the wider social, economic and environmental implication of widespread adoption of the new technologies

    Elastic response of [111]-tunneling impurities

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    We study the dynamic response of a [111] quantum impurity, such as lithium or cyanide in alkali halides, with respect to an external field coupling to the elastic quadrupole moment. Because of the particular level structure of a eight-state system on a cubic site, the elastic response function shows a biexponential relaxation feature and a van Vleck type contribution with a resonance frequency that is twice the tunnel frequency Δ/\Delta/\hbar. This basically differs from the dielectric response that does not show relaxation. Moreover, we show that the elastic response of a [111] impurity cannot be reduced to that of a two-level system. In the experimental part, we report on recent sound velocity and internal friction measurements on KCl doped with cyanide at various concentrations. At low doping (45 ppm) we find the dynamics of a single [111] impurity, whereas at higher concentrations (4700 ppm) the elastic response rather indicates strongly correlated defects. Our theoretical model provides a good description of the temperature dependence of δv/v\delta v/v and Q1Q^{-1} at low doping, in particular the relaxation peaks, the absolute values of the amplitude, and the resonant contributions. From our fits we obtain the value of the elastic deformation potential γt=0.192\gamma_t=0.192 eV.Comment: 19 pages, 5 figure

    Soft Interaction Between Dissolved Dendrimers: Theory and Experiment

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    Using small-angle neutron scattering and liquid integral equation theory, we relate the structure factor of flexible dendrimers of 4th generation to their average shape. The shape is measured as a radial density profile of monomers belonging to a single dendrimer. From that, we derive an effective interaction of Gaussian form between pairs of dendrimers and compute the structure factor using the hypernetted chain approximation. Excellent agreement with the corresponding experimental results is obtained, without the use of adjustable parameters. The present analysis thus strongly supports the previous finding that flexible dendrimers of low generation present fluctuating structures akin to star polymers.Comment: 20 pages, 4 figures, submitted to Macromolecules on July 24, 200

    Developing a nationally appropriate mitigation measure from the greenhouse gas abatement potential from livestock production in the Brazilian Cerrado.

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    Brazil is one of the first major developing countries to commit to a national greenhouse gas (GHG) emissions target that requires a reduction of between 36.1% and 38.9% relative to baseline emissions by 2020. The country intends to submit to agricultural emissions reductions as part of this target with livestock production identified as offering significant abatement potentia

    Low temperature acoustic properties of amorphous silica and the Tunneling Model

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    Internal friction and speed of sound of a-SiO(2) was measured above 6 mK using a torsional oscillator at 90 kHz, controlling for thermal decoupling, non-linear effects, and clamping losses. Strain amplitudes e(A) = 10^{-8} mark the transition between the linear and non-linear regime. In the linear regime, excellent agreement with the Tunneling Model was observed for both the internal friction and speed of sound, with a cut-off energy of E(min) = 6.6 mK. In the non-linear regime, two different behaviors were observed. Above 10 mK the behavior was typical for non-linear harmonic oscillators, while below 10 mK a different behavior was found. Its origin is not understood.Comment: 1 tex file, 6 figure

    Future proofing a long-term agricultural experiment for decades to come : Relocation and redesign

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    We are extremely grateful to generations of staff at SRUC and its predecessor organisations (NOSCA and SAC) for maintaining the Woodlands Field experiments at Craibstone over 100 years and to I&N Campbell who carefully prepared the new site and moved the soils in July 2021. The move of the soils was funded by SRUC. The molecular analysis of the soils from the pH experiment was conducted within the Soil Biology and Soil Health (SBSH) Partnership, funded by the Agriculture and Horticulture Development Board (AHDB) and the British Beet Research Organisation (BBRO) in the United Kingdom. We also gratefully acknowledge many colleagues from research and consultancy organisations in the UK and Europe who contributed to discussions during the redesign process. Professor Tony Edwards and Dr John Baddeley were both integral to the decision to move and redesign the pH Experiment. We are grateful to Allan Lilly, James Hutton Institute for allowing us to archive soils from both Woodlands Field experiments in the National Soils Archive. Thank you to Rosie Boyko and Nicola Holden (SRUC) and John Elphinstone (FERA) for useful discussions on the new experimental designs and the manuscript.Peer reviewe

    Biological efficiency profiles over the lactation period in multiparous high-producing dairy cows under divergent production systems

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    The study examined variation in energetic-efficiency profiles among production systems and cow parities. Further, the correlation between cows' body condition score (BCS) and energetic efficiency over the lactation period was determined. Biological efficiency was defined using four measures of production efficiency and two measures of energetic efficiency. The following were measures of energetic efficiency: the net energy intake required to produce 1 kg milk solids (NEin / MS) and the proportion of net energy utilized for milk production after accounting for maintenance (NElact / (NEin- NEm)). Seven years of data were gathered from a total of 595 Holstein-Friesian cows in a long-term genetics × feeding–management interaction project. Two feeding regimes – High forage (HF) and Low forage (LF) – were applied to each of two genetic lines (Control (C) and Select (S)), giving four dairy production systems: Low Forage Control (LFC), Low Forage Select (LFS), High Forage Control (HFC) and High Forage Select (HFS). LFS was the most efficient system using all measures. Variation in the rate and scale of change at which the cows' energetic efficiency declined over lactation was significantly different (P < 0.001) amongst different dairy production systems and parities. Loss of efficiency over the lactation period was lower in Select cows than in Control cows and increased with parity. The trajectory of energetic-efficiency profiles was influenced by cow genetic line, and yet the level of the efficiency profile was influenced by the feeding regime. There was a strong relationship between BCS and energetic efficiency. Continued in situ monitoring of cows' biological efficiency may enable optimal management of dairy systems
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