5,210 research outputs found

    Truth Table Invariant Cylindrical Algebraic Decomposition by Regular Chains

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    A new algorithm to compute cylindrical algebraic decompositions (CADs) is presented, building on two recent advances. Firstly, the output is truth table invariant (a TTICAD) meaning given formulae have constant truth value on each cell of the decomposition. Secondly, the computation uses regular chains theory to first build a cylindrical decomposition of complex space (CCD) incrementally by polynomial. Significant modification of the regular chains technology was used to achieve the more sophisticated invariance criteria. Experimental results on an implementation in the RegularChains Library for Maple verify that combining these advances gives an algorithm superior to its individual components and competitive with the state of the art

    Radiological Characterization of a Uranium Processing Facility

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    This document describes the plan that was developed and is being carried out at the Oak Ridge Y-12 Plant to provide data needed for radiological characterization of the site in anticipation of new posting regulations provided in Title 10, Code of Federal Regulations, Part 835, as codified from Volume 58, Number 238 of the Federal Register. The characterization plan addresses the entire site in terms of three categories: 1) Outdoor paved surfaces, 2) buildings, and 3) outdoor non-paved surfaces. Instruments chosen for use in this project are described, as well as survey techniques and the data management scheme. A quantitative assessment of the effectiveness and adequacy of the survey plan for paved surfaces is also provided

    Generalised Elliptic Functions

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    We consider multiply periodic functions, sometimes called Abelian functions, defined with respect to the period matrices associated with classes of algebraic curves. We realise them as generalisations of the Weierstras P-function using two different approaches. These functions arise naturally as solutions to some of the important equations of mathematical physics and their differential equations, addition formulae, and applications have all been recent topics of study. The first approach discussed sees the functions defined as logarithmic derivatives of the sigma-function, a modified Riemann theta-function. We can make use of known properties of the sigma function to derive power series expansions and in turn the properties mentioned above. This approach has been extended to a wide range of non hyperelliptic and higher genus curves and an overview of recent results is given. The second approach defines the functions algebraically, after first modifying the curve into its equivariant form. This approach allows the use of representation theory to derive a range of results at lower computational cost. We discuss the development of this theory for hyperelliptic curves and how it may be extended in the future.Comment: 16 page

    Deriving bases for Abelian functions

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    We present a new method to explicitly define Abelian functions associated with algebraic curves, for the purpose of finding bases for the relevant vector spaces of such functions. We demonstrate the procedure with the functions associated with a trigonal curve of genus four. The main motivation for the construction of such bases is that it allows systematic methods for the derivation of the addition formulae and differential equations satisfied by the functions. We present a new 3-term 2-variable addition formulae and a complete set of differential equations to generalise the classic Weierstrass identities for the case of the trigonal curve of genus four.Comment: 35page

    Unmasking quality: exploring meanings of health by doing art

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    This paper arises from a presentation at the ‘Quality in Healthcare’ symposium at Cumberland Lodge, England, in 2013. MK, CR and SH conceived the paper and led the writing of the manuscript. JF, JL-D, AC, DE contributed substantially to the intellectual content of the paper through providing critical commentary and interpretation. All authors read and approved the final manuscript

    Far-infrared spectra of CO2 clathrate hydrate frosts

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    As a product of our interest in remote sensing of planetary ices, frost samples of CO2 clathrate hydrate were grown by depositing water vapor on a cooled surface and pressurizing the resulting water frost with CO2 gas. At pressures above the dissociation pressure of the clathrate, the samples exhibit an absorption peak at 75 cm (sup -1). At pressures below the dissociation pressure, the peak disappears. Since the free CO2 molecule does not have rotational or vibrational absorption in this region, the absorption is attributed to a CO2 rattling mode within a clathrate cage

    Reviewing research evidence and the case of participation in sport and physical recreation by black and minority ethnic communities

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    The paper addresses the implications of using the process of systematic review in the many areas of leisure where there is a dearth of material that would be admitted into conventional Cochrane Reviews. This raises important questions about what constitutes legitimate knowledge, questions that are of critical import not just to leisure scholars, but to the formulation of policy. The search for certainty in an area that lacks conceptual consensus results in an epistemological imperialism that takes a geocentric form. While clearly, there is a need for good research design whatever the style of research, we contend that the wholesale rejection of insightful research is profligate and foolhardy. A mechanism has to be found to capitalise on good quality research of whatever form. In that search, we draw upon our experience of conducting a review of the material available on participation in sport and physical recreation by people from Black and minority ethnic groups. The paper concludes with a proposal for a more productive review process that makes better use of the full panoply of good quality research available. © 2012 © 2012 Taylor & Francis

    Capital structure and its determinants in the United Kingdom – a decompositional analysis

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    Prior research on capital structure by Rajan and Zingales (1995) suggests that the level of gearing in UK companies is positively related to size and tangibility, and negatively correlated with profitability and the level of growth opportunities. However, as argued by Harris and Raviv (1991), 'The interpretation of results must be tempered by an awareness of the difficulties involved in measuring both leverage and the explanatory variables of interest'. In this study the focus is on the difficulties of measuring gearing, and the sensitivity of Rajan and Zingales' results to variations in gearing measures are tested. Based on an analysis of the capital structure of 822 UK companies, Rajan and Zingales' results are found to be highly definitional-dependent. The determinants of gearing appear to vary significantly, depending upon which component of debt is being analysed. In particular, significant differences are found in the determinants of long- and short-term forms of debt. Given that trade credit and equivalent, on average, accounts for more than 62% of total debt, the results are particularly sensitive to whether such debt is included in the gearing measure. It is argued, therefore, that analysis of capital structure is incomplete without a detailed examination of all forms of corporate debt

    Climate change adaptation planning and cross-sectoral policy coherence in southern Africa

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    The post-2015 development agenda requires policy coherence, where achievement of development goals in one sector does not undermine the achievement of the goals of another. It also recognises that cross-cutting issues like adaptation to climate change need to be mainstreamed across multiple sectors. This paper presents a policy analysis using the cases of Malawi, Tanzania and Zambia. It analyses the water management and agricultural strategies and approaches identified in a variety of policies and plans. These include national sector policies for water and agriculture, National Development Plans, and climate change policies and strategies, including National Adaptation Programmes of Action and the Intended Nationally Determined Contributions submitted prior to the 2015 United Nations Framework Convention on Climate Change Conference of the Parties. It assesses the extent to which policies are coherent with one another with regard to their treatment of climate change adaptation using Qualitative Document Analysis. Findings identify that sector policies show some degree of cross-thematic coherence, in particular around their acknowledgement of the importance to address disaster management of floods and droughts. However, policy statements are typified by a relative lack of recognition of the need to develop supporting instruments and strategies that address climate adaptation needs over longer timeframes. Climate change policies explicitly call for significant investment in adaptation from the international community. Where coherence between sector and climate policies and strategies is strongest, the more recent climate policies largely repackage existing sectoral policy statements. These findings can be understood in the context of the uncertainty of climate change impacts for the longer term (for which a wider variety of adaptations are identified), alongside more event-driven disaster management planning where the impacts are more immediate and obviously evident. This prioritisation is also linked to development needs and the short-term nature of political cycles and economic gain. For climate-resilient policy decision-making to make further headway, we argue that governments need to embrace cross-sectoral planning more pro- actively in order to foster greater policy coherence and to deliver more climate resilient agriculture and water management
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