493 research outputs found

    On string integrability. A journey through the two-dimensional hidden symmetries in the AdS/CFT dualities

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    One of the main topics in the modern String Theory are the AdS/CFT dualities. Proving such conjectures is extremely difficult since the gauge and string theory perturbative regimes do not overlap. In this perspective, the discovery of infinitely many conserved charges, i.e. the integrability, in the planar AdS/CFT has allowed us to reach immense progresses in understanding and confirming the duality. We review the fundamental concepts and properties of integrability in two-dimensional sigma-models and in the AdS/CFT context. The first part is focused on the AdS_5/CFT_4 duality, especially the classical and quantum integrability of the type IIB superstring on AdS_5 x S^5 are discussed in both pure spinor and Green-Schwarz formulations. The second part is dedicated to the AdS_4/CFT_3 duality with particular attention to the type IIA superstring on AdS_4 x CP^3 and its integrability. This review is based on a shortened and revised version of the author's PhD thesis, discussed at Uppsala University in September 2009.Comment: 116 pages, 11 figures, to be published in Advances in High Energy Physics, Special Issue on ''Gauge/String Duality'

    Aspects of quantum integrability for pure spinor superstring in AdS(5)xS(5)

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    We consider the monodromy matrix for the pure spinor IIB superstring on AdS5×S5AdS_5\times S^5 at leading order at strong coupling, in particular its variation under an infinitesimal and continuous deformation of the contour. Such variation is equivalent to the insertion of a local operator. Demanding the BRST-closure for such an operator rules out its existence, implying that the monodromy matrix remains contour-independent at the first order in perturbation theory. Furthermore we explicitly compute the field strength corresponding to the flat connections up to leading order and directly check that it is free from logarithmic divergences. The absence of anomaly in the coordinate transformation of the monodromy matrix and the UV-finiteness of the curvature tensor finally imply the integrability of the pure spinor superstring at the first order.Comment: 44 pages; 4 figure

    The Paraprofessional Conundrum: Why We Need Alternative Support Strategies

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    This four-page article describes a conundrum facing schools utilizing paraprofessionals to support students receiving special education. It considers three factors: (a) asked to engage in teacher-type instructional roles, (b) trained and supervised for teacher-type instructional roles, and (c) compensation commensurate with teacher-type instructional roles across six combinations. Regardless of whether or not the factors are present or not it often leads to series of undesirable outcomes. The article suggest a series of alternatives

    Guidelines for Selecting Alternatives to Overreliance on Paraprofessionals

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    The Guidelines for Selecting Alternatives to Overreliance on Paraprofessionals is a field-tested schhol-based planning process. Support for the preparation of this article was provided by the United States Department of Education, Office of Special Education and Rehabilitative Services under the funding category, Model Demonstration Projects for Children and Youth with Disabilities, CFDA 84.324M (H324M02007), awarded to the Center on Disability and Community Inclusion at the University of Vermont. The contents of this document reflect the ideas and positions of the authors and do not necessarily reflect the ideas or positions of the U.S. Department of Education; therefore, no official endorsement should be inferred

    Alternatives to Overreliance or Inappropriate Utilization of Paraprofessionals in Special Education

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    This article describes 12 alternatives to overreliance or Inappropriate utilization of paraprofessionals in special education based utilization in American schools. Support for the preparation of this article was provided by the United States Department of Education, Office of Special Education Programs, under the funding category, Model Demonstration Projects for Children and Youth with Disabilities, CFDA 84.324M (Project EVOLVE, H324M02007), awarded to the Center on Disability and Community Inclusion at the University of Vermont. The contents of this paper reflect the ideas and positions of the authors and do not necessarily reflect the ideas or positions of the U.S. Department of Education; therefore, no official endorsement should be inferred

    APPROCCIO FREQUENTISTA E BAYESIANO, DUE MODI DIVERSI DI VEDERE LA STESSA REALTÀ: APPLICAZIONI ALLA MODULAZIONE DEL DOLORE A MISURE RIPETUTE

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    Abstract Introduction. Placebo effect in the field of pain modulation is still less analyzed and explained, and the reasons of this don\u2019t know. A computational evaluation of this phenomena is proposed trying to find a first explanation. Materials and methods. A comparison between a classical frequentist approach and a Bayesian one is presented basing on a model for repeated measures to test experimental data obtained from eight healthy subjects. Results. The results, in both of the statistical approaches, demonstrates that the placebo effect in the pain modulation, exists and is evident

    Operator Product Expansion for Pure Spinor Superstring on AdS(5)*S(5)

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    The tree-level operator product expansion coefficients of the matter currents are calculated in the pure spinor formalism for type IIB superstring in the AdS(5)*S(5) background.Comment: 18 pages, no figure, corrected typos and added acknowledgement
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