4,362 research outputs found

    First experimental realization of the Dirac oscillator

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    We present the first experimental microwave realization of the one-dimensional Dirac oscillator, a paradigm in exactly solvable relativistic systems. The experiment relies on a relation of the Dirac oscillator to a corresponding tight-binding system. This tight-binding system is implemented as a microwave system by a chain of coupled dielectric disks, where the coupling is evanescent and can be adjusted appropriately. The resonances of the finite microwave system yields the spectrum of the one-dimensional Dirac oscillator with and without mass term. The flexibility of the experimental set-up allows the implementation of other one-dimensional Dirac type equations.Comment: 6 figures, 5 page

    Correlations between spectra with different symmetry: any chance to be observed?

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    A standard assumption in quantum chaology is the absence of correlation between spectra pertaining to different symmetries. Doubts were raised about this statement for several reasons, in particular, because in semiclassics spectra of different symmetry are expressed in terms of the same set of periodic orbits. We reexamine this question and find absence of correlation in the universal regime. In the case of continuous symmetry the problem is reduced to parametric correlation, and we expect correlations to be present up to a certain time which is essentially classical but larger than the ballistic time

    Invariant Manifolds and Collective Coordinates

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    We introduce suitable coordinate systems for interacting many-body systems with invariant manifolds. These are Cartesian in coordinate and momentum space and chosen such that several components are identically zero for motion on the invariant manifold. In this sense these coordinates are collective. We make a connection to Zickendraht's collective coordinates and present certain configurations of few-body systems where rotations and vibrations decouple from single-particle motion. These configurations do not depend on details of the interaction.Comment: 15 pages, 2 EPS-figures, uses psfig.st

    Ancient Egypt 1916 Part 2

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    Part 2 of the 1916 Ancient Egypt books. Contents include the Gorringe collection, an early figure of Taurt, Egypt in the Grail Romance, and the queenly title, XXIInd dynasty.https://knowledge.e.southern.edu/kweeks_coll/1006/thumbnail.jp

    Quantum and classical echoes in scattering systems described by simple Smale horseshoes

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    We explore the quantum scattering of systems classically described by binary and other low order Smale horseshoes, in a stage of development where the stable island associated with the inner periodic orbit is large, but chaos around this island is well developed. For short incoming pulses we find periodic echoes modulating an exponential decay over many periods. The period is directly related to the development stage of the horseshoe. We exemplify our studies with a one-dimensional system periodically kicked in time and we mention possible experiments.Comment: 7 pages with 6 reduced quality figures! Please contact the authors ([email protected]) for an original good quality pre-prin

    Next-to-next-to-leading order fits to CCFR'97 xF3xF_3 data and infrared renormalons

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    We briefly summarize the outcomes of our recent improved fits to the experimental data of CCFR collaboration for xF3xF_3 structure function of ΜN\nu N deep-inelastic scattering at the next-to-next-to-leading order. Special attention is paid to the extraction of αs(MZ)\alpha_s(M_Z) and the parameter of the infrared renormalon model for 1/Q21/Q^2-correction at different orders of perturbation theory. The results can be of interest for planning similar studies using possible future data of Neutrino Factories.Comment: 3 pages, presented at WG3 of 4th NuFact'02 Workshop, London 1-6 July, 200

    Interactional positioning and narrative self-construction in the first session of psychodynamic-interpersonal psychotherapy

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    The purpose of this study is to identify possible session one indicators of end of treatment psychotherapy outcome using the framework of three types of interactional positioning; client’s self-positioning, client’s positioning between narrated self and different partners, and the positioning between client and therapist. Three successful cases of 8-session psychodynamic-interpersonal (PI) therapy were selected on the basis of client Beck Depression Inventory scores. One unsuccessful case was also selected against which identified patterns could be tested. The successful clients were more descriptive about their problems and demonstrated active rapport-building, while the therapist used positionings expressed by the client in order to explore the positionings developed between them during therapy. The unsuccessful case was characterized by lack of positive self-comment, minimization of agentic self-capacity, and empathy-disrupting narrative confusions. We conclude that the theory of interactional positioning has been useful in identifying patterns worth exploring as early indicators of success in PI therapy

    Appearance, happiness and success: ‘what is beautiful is good’

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    In our beauty-obsessed world, where incessant dissatisfaction with appearance is considered to be ‘normal’, it can seem as though those with ‘good looks’ are the ones who have it all. But is it the case that being beautiful can get you further in life? Nicola Stock explores the human fascination with keeping up appearances and highlights the impact of attempting to meet modern unrealistic ideals of beauty
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