88,261 research outputs found

    Prospects for transient gravitational waves at r-mode frequencies associated with pulsar glitches

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    t Glitches in pulsars are likely to trigger oscillation modes in the fluid interior of neutron stars. We examined these oscillations specifically at r-mode frequencies. The excited r-modes will emit gravitational waves and can have long damping time scales (minutes - days). We use simple estimates of how much energy the glitch might put into the r-mode and assess the detectability of the emitted gravitational waves with future interferometers

    Economics of organic farming (extension to OF0125)(0F0190)

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    This project OF0190 was an extension to OF0125 to cover completing the comparison data for 1997/98 and to extend the data collection by one further year (1998/99). The final reports for the two projects are therefore being submitted jointly. The OF0125 report covers the period 1995/96-1997/98, for which a detailed report was submitted to MAFF in July 1999, and a revised detailed report including a complete set of comparisons with conventional farms was submitted to MAFF, after revisions, in July 2000. That report has now been published at www.organic.aber.ac.uk/library/organic farm incomes.pdf. A detailed report for 1998/99 has been submitted to MAFF in March 2001, and will be published at the same internet site once accepted. The report presents results from research work carried out for the Ministry of Agriculture, Fisheries and Food (MAFF) on the financial performance of organic farms in 1998/99. The aim of the research was to assess the financial performance of organic farms differentiated by farm type, in order to inform MAFF policy-making with respect to organic farming, and to provide a basis for assessments by farmers, advisers and other interested parties of the farm-level implications of conversion to and continued organic farming. To provide an idea of the trends over time, where possible data for continuous samples of farms are presented for 1997/98 and 1998/99. The specific objectives were to extend the previous project (OF0125, covering 1995/96 to 1997/98) to collect and collate data on the financial performance of organic farms, differentiated by farm type . This was achieved through the collation of financial data collected under three different MAFF-funded research projects supplemented by data collected on other farm types. The samples of organic farms are small because of the limited number of organic holdings over 8 ESU (European Size Units) with identifiable holding numbers in 1996, when the previous study was started. As the sample is small there is limitation on how the results may be extrapolated to the wider population of organic farms, especially as the structure and objectives of those converting to organic production in the late 1990s may be different from those that converted in the 1970s and 1980s. Detailed financial input, output, income, liabilities and assets and some physical performance measures are presented for 1998/99. Where an identical sample of five farms is available, data are presented for 1997/98 and 1998/99 for the sample. The organic farm samples are so small that outliers (especially larger farms) have a large influence on the average. If the samples were larger, general trends would be more apparent and less influenced by individual farms; despite this, some explanation has been attempted of trends and changes in inputs, outputs and incomes. However, great care must be taken in extrapolating results. Of those farm types for which a continuous identical sample of five farms was available, Net Farm Incomes (NFI) increased for cropping (ÂŁ281/ha) and dairy farms (ÂŁ487/ha) in 1998/99 compared with 1997/98; in both cases outputs as well as inputs increased between years. Mixed farms showed an average reduction in outputs and increase in inputs, lowering the average NFI to ÂŁ15/ha in 1998/99. The five lowland cattle and sheep farms improved a negative NFI of ÂŁ161/ha in 1997/98 to a positive ÂŁ7/ha in 1998/99 through an increase in livestock outputs with a similar level of inputs to that of 1997/98. Due to the high level of farmer and spouse labour on horticultural holdings, the average Management and Investment Income (MII) of the sample was negative, but the average NFI was ÂŁ1,836/ha. On four holdings, 1998/99 average outputs were 92%, and inputs were 97% of the previous year, resulting in an average NFI in 1998/99 for that group of 75% of the 1997/98 result. The group of LFA farms, consisting of four cattle and sheep and one mixed farm, achieved an average NFI of ÂŁ72/ha in 1998/99

    Calculation of the free-free transitions in the electron-hydrogen scattering S-wave model

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    The S-wave model of electron-hydrogen scattering is evaluated using the convergent close-coupling method with an emphasis on scattering from excited states including an initial state from the target continuum. Convergence is found for discrete excitations and the elastic free-free transition. The latter is particularly interesting given the corresponding potential matrix elements are divergent

    An alternative basis for the Kauffman bracket skein module of the Solid Torus via braids

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    In this paper we give an alternative basis, BST\mathcal{B}_{\rm ST}, for the Kauffman bracket skein module of the solid torus, KBSM(ST){\rm KBSM}\left({\rm ST}\right). The basis BST\mathcal{B}_{\rm ST} is obtained with the use of the Tempereley--Lieb algebra of type B and it is appropriate for computing the Kauffman bracket skein module of the lens spaces L(p,q)L(p, q) via braids.Comment: 14 pages, 5 figure

    One-loop renormalisation of N=1/2 supersymmetric gauge theory with a superpotential

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    We construct a superpotential for the general N=1/2 supersymmetric gauge theory coupled to chiral matter in the fundamental and adjoint representations, and investigate the one-loop renormalisability of the theories.Comment: 67 pages, including 17 figures. Plain TeX. Uses Harvmac and epsf. Combined and condensed version of hep-th/0607194 and hep-th/0607195 with some added material including in particular a generalisation of the Lunin-Rey classification of potentially divergent operator

    The energy loss of relativistic cosmic ray muons in plastic scintillator

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    The energy loss for a small area plastic phosphor scintillation counter as a function of particle momentum has been investigated using the Durham Mk 3 Spectrograph with the intention of clarifying the position regarding the decrease in energy loss for particles of momenta greater than 10 Gev(_c) recently predicted "by Tsytovitch. The results0are consistent with the theory of Sternheiraer and show only a slight decrease in the momentum range 10 GeV(_c) to 100 GeV(_c) which is much less than that predicted by Tsytovitch

    Metastable Flux Configurations and de Sitter Spaces

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    We derive stability conditions for the critical points of the no-scale scalar potential governing the dynamics of the complex structure moduli and the axio-dilaton in compactifications of type IIB string theory on Calabi-Yau three-folds. We discuss a concrete example of a T^6 orientifold. We then consider the four-dimensional theory obtained from compactifications of type IIB string theory on non-geometric backgrounds which are mirror to rigid Calabi-Yau manifolds and show that the complex structure moduli fields can be stabilized in terms of H_{RR} only, i.e. with no need of orientifold projection. The stabilization of all the fields at weak coupling, including the axio-dilaton, may require to break supersymmetry in the presence of H_{NS} flux or corrections to the scalar potential.Comment: 24 page

    Wheat forecast economics effect study

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    A model to assess the value of improved information regarding the inventories, productions, exports, and imports of crop on a worldwide basis is discussed. A previously proposed model is interpreted in a stochastic control setting and the underlying assumptions of the model are revealed. In solving the stochastic optimization problem, the Markov programming approach is much more powerful and exact as compared to the dynamic programming-simulation approach of the original model. The convergence of a dual variable Markov programming algorithm is shown to be fast and efficient. A computer program for the general model of multicountry-multiperiod is developed. As an example, the case of one country-two periods is treated and the results are presented in detail. A comparison with the original model results reveals certain interesting aspects of the algorithms and the dependence of the value of information on the incremental cost function

    Using a fuzzy inference system to control a pumped storage hydro plant

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    The paper discusses the development of a fuzzy inference system (FIS) based governor control for a pumped storage hydroelectric plant. The First Hydro Company's plant at Dinorwig in North Wales is the largest of its kind in Europe and is mainly used for frequency control of the UK electrical grid. In previous investigations, a detailed model of the plant was developed using MATLAB(R)/SIMULINK(R) and this is now being used to compare FIS governor operation with the proportional-integral-derivative (PID) controller currently used. The paper describes the development of an FIS governor, and shows that its response to a step increase in load is superior to the PID under certain conditions of load. The paper proceeds to discuss the implications of these results in view of the possible practical application of an FIS governor at the Dinorwig plant
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