22,481 research outputs found

    A-D-E Polynomial and Rogers--Ramanujan Identities

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    We conjecture polynomial identities which imply Rogers--Ramanujan type identities for branching functions associated with the cosets (G(1))ℓ−1⊗(G(1))1/(G(1))ℓ({\cal G}^{(1)})_{\ell-1}\otimes ({\cal G}^{(1)})_{1} / ({\cal G}^{(1)})_{\ell}, with G{\cal G}=An−1_{n-1} \mbox{(ℓ≥2)(\ell\geq 2)}, Dn−1_{n-1} (ℓ≥2)(\ell\geq 2), E6,7,8_{6,7,8} (ℓ=2)(\ell=2). In support of our conjectures we establish the correct behaviour under level-rank duality for G\cal G=An−1_{n-1} and show that the A-D-E Rogers--Ramanujan identities have the expected q→1−q\to 1^{-} asymptotics in terms of dilogarithm identities. Possible generalizations to arbitrary cosets are also discussed briefly.Comment: 19 pages, Latex, 1 Postscript figur

    The stability of new transparent polymeric materials: The epoxy trimethoxyboroxine system. Part 1: The preparation, characterization and curing of epoxy resins and their copolymers

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    The effects of resin composition, curing conditions fillers, and flame retardant additives on the flammability of diglycidyl ether of bisphenol-A (DGEBA) as measured by the oxygen index is examined. The oxygen index of DGEBA cured with various curing agents was between 0.198 to 0.238. Fillers and flame retardant additives can increase the oxygen index dependent on the material and the amount used. Changes in the basic cured resin properties can be anticipated with the addition of noncompatible additives. High flame resistant epoxy resins with good stability and mechanical properties are investigated

    Density regulation in strictly metric-free swarms

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    There is now experimental evidence that nearest-neighbour interactions in flocks of birds are metric free, i.e. they have no characteristic interaction length scale. However, models that involve interactions between neighbours that are assigned topologically are naturally invariant under spatial expansion, supporting a continuous reduction in density towards zero, unless additional cohesive interactions are introduced or the density is artificially controlled, e.g. via a finite system size. We propose a solution that involves a metric-free motional bias on those individuals that are topologically identified to be on an edge of the swarm. This model has only two primary control parameters, one controlling the relative strength of stochastic noise to the degree of co-alignment and another controlling the degree of the motional bias for those on the edge, relative to the tendency to co-align. We find a novel power-law scaling of the real-space density with the number of individuals N as well as a familiar order-to-disorder transition

    AFES Miscellaneous Publication 2010-02

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    Research has been conducted since 2001 to assist growers in identifying components of peony field cut flower production and distribution from field selection and planting to post harvest handling and packaging for export. This experiment addressed three components of the production cycle: field planting dates, root quality and plant productivity, and post harvest handling of cut stems. In a comparison of planting times (autumn, spring or as containerized plants in mid summer), ‘Sarah Bernhardt’ and ‘Felix Crouse’ showed no difference in shoot number and growth one full year after planting. ‘Duchess de Nemours’ and ‘Alexander Fleming’ showed significant reductions in growth compared to the other cultivars, and we suspect disease rather than planting time as the problem. All treatments where bud break had occurred in storage with ‘Duchess de Nemours’ and ‘Alexander Fleming,’ new shoots rotted, and recovery was slow. A treatment of elemental sulfur was not sufficient to protect roots from storage rot. ‘Sarah Bernhardt’ roots and crown buds were weighed, counted and measured prior to planting in order to learn if a correlation exists between root quality and subsequent growth and flowering. Three root attributes were correlated with the total number of stems produced: total number of eyes per plant, total number of roots per plant, and root fresh weight. Characteristics such as root length and maximum diameter were not correlated with subsequent growth. We found no relationship between any root characteristics and the number of flowering stems and foliage height in the first year. The attributes that showed correlation could not be fitted to a linear or curvilinear model explaining the nature of the correlation. Larger sample sizes will be necessary to clarify these relationships. The best method for handling peony cut flowers for greatest vase life is to cut peonies dry and store them dry in a cooler (34°F) at 80+% relative humidity until shipping. Use of water in buckets in the field or pulsing flowers with water in the cooler does not improve vase life of peonies. Under optimum conditions, ‘Sarah Bernhardt’ peonies lasted up to 15 days in a vase, 8-9 days from bud break to full bloom, and an additional 5-6 days in full bloom. Chilling in a cooler is the most important attribute to long vase life

    The impact of the graduated driver licence scheme on road traffic accident youth mortality in New Zealand

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    This paper examines the impact of the introduction of New Zealand’s Graduated Driving Licence System (GDLS) on patterns of road traffic accident mortality amongst the young driving population from 1980 to 2001. Results show that the mortality rate has declined, but that rates in New Zealand are three times greater than in England and Wales and twice those of Scotland. When the data is adjusted to take account of differences in the minimum driving age, rates remain consistently higher in New Zealand and the proportional reduction in road traffic accident youth mortality is not significantly better than that experienced in Great Britain

    Effects on Amorphous Silicon Photovoltaic Performance from High-temperature Annealing Pulses in Photovoltaic Thermal Hybrid Devices

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    There is a renewed interest in photovoltaic solar thermal (PVT) hybrid systems, which harvest solar energy for heat and electricity. Typically, a main focus of a PVT system is to cool the photovoltaic (PV) cells to improve the electrical performance, however, this causes the thermal component to under-perform compared to a solar thermal collector. The low temperature coefficients of amorphous silicon (a-Si:H) allow for the PV cells to be operated at higher temperatures and are a potential candidate for a more symbiotic PVT system. The fundamental challenge of a-Si:H PV is light-induced degradation known as the Staebler-Wronski effect (SWE). Fortunately, SWE is reversible and the a-Si:H PV efficiency can be returned to its initial state if the cell is annealed. Thus an opportunity exists to deposit a-Si:H directly on the solar thermal absorber plate where the cells could reach the high temperatures required for annealing. In this study, this opportunity is explored experimentally. First a-Si:H PV cells were annealed for 1 hour at 100\degreeC on a 12 hour cycle and for the remaining time the cells were degraded at 50\degreeC in order to simulate stagnation of a PVT system for 1 hour once a day. It was found that, when comparing the cells after stabilization at normal 50\degreeC degradation, this annealing sequence resulted in a 10.6% energy gain when compared to a cell that was only degraded at 50\degreeC
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