96 research outputs found

    Poisson-Lie group of pseudodifferential symbols

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    We introduce a Lie bialgebra structure on the central extension of the Lie algebra of differential operators on the line and the circle (with scalar or matrix coefficients). This defines a Poisson--Lie structure on the dual group of pseudodifferential symbols of an arbitrary real (or complex) order. We show that the usual (second) Benney, KdV (or GL_n--Adler--Gelfand--Dickey) and KP Poisson structures are naturally realized as restrictions of this Poisson structure to submanifolds of this ``universal'' Poisson--Lie group. Moreover, the reduced (=SL_n) versions of these manifolds (W_n-algebras in physical terminology) can be viewed as subspaces of the quotient (or Poisson reduction) of this Poisson--Lie group by the dressing action of the group of functions. Finally, we define an infinite set of functions in involution on the Poisson--Lie group that give the standard families of Hamiltonians when restricted to the submanifolds mentioned above. The Poisson structure and Hamiltonians on the whole group interpolate between the Poisson structures and Hamiltonians of Benney, KP and KdV flows. We also discuss the geometrical meaning of W_\infty as a limit of Poisson algebras W_\epsilon as \epsilon goes to 0.Comment: 64 pages, no figure

    Non-Local Matrix Generalizations of W-Algebras

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    There is a standard way to define two symplectic (hamiltonian) structures, the first and second Gelfand-Dikii brackets, on the space of ordinary linear differential operators of order mm, L=dm+U1dm1+U2dm2++UmL = -d^m + U_1 d^{m-1} + U_2 d^{m-2} + \ldots + U_m. In this paper, I consider in detail the case where the UkU_k are n×nn\times n-matrix-valued functions, with particular emphasis on the (more interesting) second Gelfand-Dikii bracket. Of particular interest is the reduction to the symplectic submanifold U1=0U_1=0. This reduction gives rise to matrix generalizations of (the classical version of) the {\it non-linear} WmW_m-algebras, called Vm,nV_{m,n}-algebras. The non-commutativity of the matrices leads to {\it non-local} terms in these Vm,nV_{m,n}-algebras. I show that these algebras contain a conformal Virasoro subalgebra and that combinations WkW_k of the UkU_k can be formed that are n×nn\times n-matrices of conformally primary fields of spin kk, in analogy with the scalar case n=1n=1. In general however, the Vm,nV_{m,n}-algebras have a much richer structure than the WmW_m-algebras as can be seen on the examples of the {\it non-linear} and {\it non-local} Poisson brackets of any two matrix elements of U2U_2 or W3W_3 which I work out explicitly for all mm and nn. A matrix Miura transformation is derived, mapping these complicated second Gelfand-Dikii brackets of the UkU_k to a set of much simpler Poisson brackets, providing the analogue of the free-field realization of the WmW_m-algebras.Comment: 43 pages, a reference and a remark on the conformal properties for U10U_1\ne 0 adde

    The Physical Principles of Quantum Mechanics. A critical review

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    The standard presentation of the principles of quantum mechanics is critically reviewed both from the experimental/operational point and with respect to the request of mathematical consistency and logical economy. A simpler and more physically motivated formulation is discussed. The existence of non commuting observables, which characterizes quantum mechanics with respect to classical mechanics, is related to operationally testable complementarity relations, rather than to uncertainty relations. The drawbacks of Dirac argument for canonical quantization are avoided by a more geometrical approach.Comment: Bibliography and section 2.1 slightly improve

    Quivers from Matrix Factorizations

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    We discuss how matrix factorizations offer a practical method of computing the quiver and associated superpotential for a hypersurface singularity. This method also yields explicit geometrical interpretations of D-branes (i.e., quiver representations) on a resolution given in terms of Grassmannians. As an example we analyze some non-toric singularities which are resolved by a single CP1 but have "length" greater than one. These examples have a much richer structure than conifolds. A picture is proposed that relates matrix factorizations in Landau-Ginzburg theories to the way that matrix factorizations are used in this paper to perform noncommutative resolutions.Comment: 33 pages, (minor changes

    A Historiometric Examination of Machiavellianism and a New Taxonomy of Leadership

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    Although researchers have extensively examined the relationship between charismatic leadership and Machiavellianism (Deluga, 2001; Gardner & Avolio, 1995; House & Howell, 1992), there has been a lack of investigation of Machiavellianism in relation to alternative forms of outstanding leadership. Thus, the purpose of this investigation was to examine the relationship between Machiavellianism and a new taxonomy of outstanding leadership comprised of charismatic, ideological, and pragmatic leaders. Using an historiometric approach, raters assessed Machiavellianism via the communications of 120 outstanding leaders in organizations across the domains of business, political, military, and religious institutions. Academic biographies were used to assess twelve general performance measures as well as twelve general controls and five communication specific controls. The results indicated that differing levels of Machiavellianism is evidenced across the differing leader types as well as differing leader orientation. Additionally, Machiavellianism appears negatively related to performance, though less so when type and orientation are taken into account.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

    The Importance of Context in Managerial Work: The Case of Senior Hotel Managers in Greece

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    Qualitative research on the interplay between context and hospitality managerial work has not been previously addressed in the literature. Based on the works of Johns (2006) and Dierdorff et al. (2009), this research suggests that luxury senior hotel managers (GMs and department managers) are to a certain degree recipients of contextual/cultural influences, depending on the ownership status of the hotel. It is also argued that managerial work is shaped and exercised by a set of moderating factors, which are unique for each individual. Overall, the aim of this research is to increase the level of awareness and trigger further research in this topic area. © 2014 Copyright © Taylor & Francis Group, LLC

    Fast shuttling of ions in a scalable Penning trap array

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    We report on the design and testing of an array of Penning ion traps made from printed circuit board. The system enables fast shuttling of ions from one trapping zone to another, which could be of use in quantum information processing. We describe simulations carried out to determine the optimal potentials to be applied to the trap electrodes for enabling this movement. The results of a preliminary experiment with a cloud of laser cooled calcium ions demonstrate a round-trip shuttling efficiency of up to 75. © 2010 American Institute of Physics
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