3,424 research outputs found

    The Picaresque Novel of Spain

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    Review of books on the picaresque novel, and their treatment of the subject. The importance of this field of literature. The picaresque type as mainly and typically Spanish

    Electronic properties of antidot lattices fabricated by atomic force lithography

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    Antidot lattices were fabricated by atomic force lithography using local oxidation. High quality finite 20 x20 lattices are demonstrated with periods of 300 nm. The low temperature magnetoresistance shows well developed commensurability oscillations as well as a quenching of the Hall effect around zero magnetic field. In addition, we find B periodic oscillations superimposed on the classical commensurability peaks at temperatures as high as 1.7 K. These observations indicate the high electronic quality of our samples.Comment: Appl. Phys. Lett., in prin

    On the AdS Higher Spin / O(N) Vector Model Correspondence: degeneracy of the holographic image

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    We explore the conjectured duality between the critical O(N) vector model and minimal bosonic massless higher spin (HS) theory in AdS. In the boundary free theory, the conformal partial wave expansion (CPWE) of the four-point function of the scalar singlet bilinear is reorganized to make it explicitly crossing-symmetric and closed in the singlet sector, dual to the bulk HS gauge fields. We are able to analytically establish the factorized form of the fusion coefficients as well as the two-point function coefficient of the HS currents. We insist in directly computing the free correlators from bulk graphs with the unconventional branch. The three-point function of the scalar bilinear turns out to be an "extremal" one at d=3. The four-leg bulk exchange graph can be precisely related to the CPWs of the boundary dual scalar and its shadow. The flow in the IR by Legendre transforming at leading 1/N, following the pattern of double-trace deformations, and the assumption of degeneracy of the hologram lead to the CPWE of the scalar four-point function at IR. Here we confirm some previous results, obtained from more involved computations of skeleton graphs, as well as extend some of them from d=3 to generic dimension 2<d<4.Comment: 22 pages, 5 figure

    A Framework for Implementing Type Systems

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    Type systems are ubiquitous in the study of programming languages. Although the basic mechanisms are well understood, a new type system can still be a challenge to implement. We present the design and implementation of a domain-specific language (i.e., a functional framework) for writing type system implementations. This domain-specific language has been embedded in both Haskell and Scheme. It allows users to write down the axioms and inference rules of the type system in a stylized notation that closely resembles the formal type rules, and automates the rest of the work of type checking or type inference

    A Type Notation for Scheme

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    This report defines a type notation for Scheme. This notation was used in the undergraduate programming languages class at Iowa State in Spring 2005

    The focus of light - linear polarization breaks the rotational symmetry of the focal spot

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    We experimentally demonstrate for the first time that a linearly polarized beam is focussed to an asymmetric spot when using a high-numerical aperture focussing system. This asymmetry was predicted by Richards and Wolf [Proc.R.Soc.London A, 253, 358 (1959)] and can only be measured when a polarization insensitive sensor is placed in the focal region. We used a specially modified photodiode in a knife edge type set up to obtain highly resolved images of the total electric energy density distribution at the focus. The results are in good agreement with the predictions of a vectorial focussing theory.Comment: to be published in "Journal of Modern Optics

    Accumulation horizons and period-adding in optically injected semiconductor lasers

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    We study the hierarchical structuring of islands of stable periodic oscillations inside chaotic regions in phase diagrams of single-mode semiconductor lasers with optical injection. Phase diagrams display remarkable {\it accumulation horizons}: boundaries formed by the accumulation of infinite cascades of self-similar islands of periodic solutions of ever-increasing period. Each cascade follows a specific period-adding route. The riddling of chaotic laser phases by such networks of periodic solutions may compromise applications operating with chaotic signals such as e.g. secure communications.Comment: 4 pages, 4 figures, laser phase diagrams, to appear in Phys. Rev. E, vol. 7

    Performance demonstration of the non-intercepting Bunch Shape Monitor at UNILAC

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    Propagators and WKB-exactness in the plane wave limit of AdSxS

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    Green functions for the scalar, spinor and vector fields in a plane wave geometry arising as a Penrose limit of AdSĂ—SAdS\times S are obtained. The Schwinger-DeWitt technique directly gives the results in the plane wave background, which turns out to be WKB-exact. Therefore the structural similarity with flat space results is unveiled. In addition, based on the local character of the Penrose limit, it is claimed that for getting the correct propagators in the limit one can rely on the first terms of the direct geodesic contribution in the Schwinger-DeWitt expansion of the original propagators . This is explicitly shown for the Einstein Static Universe, which has the same Penrose limit as AdSĂ—SAdS\times S with equal radii, and for a number of other illustrative cases.Comment: 18 pages, late

    Human Escherichia coli O157:H7 Genetic Marker in Isolates of Bovine Origin

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    The antiterminator Q gene of bacteriophage 933W (Q933) was identified upstream of the stx2 gene in 90% of human disease–origin Escherichia coli O157:H7 isolates and in 44.5% of bovine isolates. Shiga toxin production was higher in Q933-positive isolates than Q933-negative isolates. This genetic marker may provide a useful molecular tool for epidemiologic studies
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