2,913 research outputs found

    Harish-Chandra integrals as nilpotent integrals

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    Recently the correlation functions of the so-called Itzykson-Zuber/Harish-Chandra integrals were computed (by one of the authors and collaborators) for all classical groups using an integration formula that relates integrals over compact groups with respect to the Haar measure and Gaussian integrals over a maximal nilpotent Lie subalgebra of their complexification. Since the integration formula a posteriori had the same form for the classical series, a conjecture was formulated that such a formula should hold for arbitrary semisimple Lie groups. We prove this conjecture using an abstract Lie-theoretic approach.Comment: 10 page

    Stringification of Chiral Dynamics: Wess-Zumino interaction

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    The QCD hadronic string is supplemented with the reparameterization-invariant boundary interaction to background chiral fields associated with pions in a way compatible with the conformal symmetry. It allows the full reconstruction of the P-even part of the Chiral Lagrangian in a good agreement with the phenomenology of P-even meson interactions. The modification of boundary interaction necessary to induce the parity-odd Chiral Dynamics (WZW action) is outlined.Comment: 5 pages, misprints removed, Talks at the 1th Workshop on Hadron Structure and QCD, 18-22.May 2004, St.Petersburg, Russia, at the Bogolubov Conference on Problems of Theoretical and Mathematical Physics, 2-6.September 2004, Dubna, Russia and at the 6th Conference on Quark Confinement and the Hadron Spectrum, 21-25.September 2004, Villasimius, Sardegna, Ital

    Shape computations without compositions

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    Parametric CAD supports design explorations through generative methods which compose and transform geometric elements. This paper argues that elementary shape computations do not always correspond to valid compositional shape structures. In many design cases generative rules correspond to compositional structures, but for relatively simple shapes and rules it is not always possible to assign a corresponding compositional structure of parts which account for all operations of the computation. This problem is brought into strong relief when design processes generate multiple compositions according to purpose, such as product structure, assembly, manufacture, etc. Is it possible to specify shape computations which generate just these compositions of parts or are there additional emergent shapes and features? In parallel, combining two compositions would require the associated combined computations to yield a valid composition. Simple examples are presented which throw light on the issues in integrating different product descriptions (i.e. compositions) within parametric CAD

    2-matrix versus complex matrix model, integrals over the unitary group as triangular integrals

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    We prove that the 2-hermitean matrix model and the complex-matrix model obey the same loop equations, and as a byproduct, we find a formula for Itzykzon-Zuber's type integrals over the unitary group. Integrals over U(n) are rewritten as gaussian integrals over triangular matrices and then computed explicitly. That formula is an efficient alternative to the former Shatashvili's formula.Comment: 29 pages, Late

    Characteristics and dynamics of surfzone transverse finger bars

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    Patches of transverse finger bars have been identified in the surf zone of Noordwijk beach (Netherlands). They consisted of three to nine elongated accumulations of sand attached to the low-tide shoreline. The bars extended up to 50 m into the inner surf zone, had an oblique orientation with respect to the shore-normal, and were quasiregularly spaced in the alongshore direction.Postprint (published version

    Equivalence of Scales and Inequality (published in Income Inequality Measurement:From Theory to Practice, J Silber (ed), Dewenter: Kluver (1999)

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    Instead of Inequality analysis sometimes neglects the problem of allowing differences in people's non-income characteristics in the comparison of income distribution, I would say, At the heart of any distributional analysis there is the problem of allowing for differences in people's non-income characteristics. We examine the role of standard equivalence scales in distributional comparisons and the welfare implications of the basis for constructing equivalence scales. We consider the use of alternative approaches that do not require the specification of a single scale and implement one of these in a practical comparison of Spain and the UK.Inequality, social welfare, equivalence scales

    Aportación al diagnóstico y cirugía de la cavidad nasal

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    Tras una revisión de las técnicas empleadas actualmente en el diagnóstico y tratamiento de los procesos patológicos de la cavidad nasal en perros y gatos se describe una técnica nueva en medicina veterinaria, similar a la utilizada con frecuencia en medicina humana, para el abordaje de la cavidad nasal a través del surco gingivolabial superior. Esta vía permite la aplicación más cómoda y más profunda de los métodos diagnósticos habituales y de la cirugía curativa o paliativa esperada en la mayoría de los casos.Having made a whole review of the techniques used at present in the diagnostic and treatment of the pathological processes of the nasal cavity in dogs and cats, it 's described a new technique in veterinary surgery, which is like the one used frequently in human medicine, to the approach to the nasal cavity through the upper gingioobuccal sulcus. This way allows a more comfortable and deep application of the current diagnostical methods and the wanted palliative or curatiue surgery in most of the cases

    The Spanish term structure of interest rates revisited: cointegration with multiple structural breaks, 1974-2010

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    In this paper we consider the possibility that a linear cointegrated regression model with multiples structural changes would provide a better empirical description of the term structure model of interest rates. Our methodology is based on instability tests recently proposed in Kejriwal and Perron (2010) as well as the cointegration test in Arai and Kurozumi (2007) and Kejriwal (2008) developed to allow for multiple breaks under the null hypothesis of cointegration.Term structure of interest rates; Cointegration; Multiple Structural Breaks.

    Supporting reinterpretation in computer-aided conceptual design

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    This paper presents research that aims to inform the development of computational tools that better support design exploration and idea transformation - key objectives in conceptual design. Analyses of experimental data from two fields - product design and architecture - suggest that the interactions of designers with their sketches can be formalised according to a finite number of generalised shape rules defined within a shape grammar. Such rules can provide a basis for the generation of alternative design concepts and they have informed the development of a prototype shape synthesis system that supports dynamic reinterpretation of shapes in design activity. The notion of 'sub-shapes' is introduced and the significance of these to perception, recognition and the development of emergent structures is discussed. The paper concludes with some speculation on how such a system might find application in a range of design fields
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