581 research outputs found

    Non-Hermitian quantum dynamics and entanglement of coupled nonlinear resonators

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    We consider a generalization of recently proposed non-Hermitian model for resonant cavities coupled by a chiral mirror by taking into account number non-conservation and nonlinear interactions. We analyze non-Hermitian quantum dynamics of populations and entanglement of the cavity modes. We find that an interplay of initial coherence and non-Hermitian coupling leads to a counterintuitive population transfer. While an initially coherent cavity mode is depleted, the other empty cavity can be populated more or less than the initially filled one. Moreover, presence of nonlinearity yields population collapse and revival as well as bipartite entanglement of the cavity modes. In addition to coupled cavities, we point out that similar models can be found in PT\mathcal{PT} symmetric Bose-Hubbard dimers of Bose-Einstein condensates or in coupled soliton-plasmon waveguides. We specifically illustrate quantum dynamics of populations and entanglement in a heuristic model that we propose for a soliton-plasmon system with soliton amplitude dependent asymmetric interaction. Degree of asymmetry, nonlinearity and coherence are examined to control plasmon excitations and soliton-plasmon entanglement. Relations to PT\mathcal{PT} symmetric lasers and Jahn-Teller systems are pointed out

    Non-Abelian pp-waves in D=4 supergravity theories

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    The non-Abelian plane waves, first found in flat spacetime by Coleman and subsequently generalized to give pp-waves in Einstein-Yang-Mills theory, are shown to be 1/2 supersymmetric solutions of a wide variety of N=1 supergravity theories coupled to scalar and vector multiplets, including the theory of SU(2) Yang-Mills coupled to an axion \sigma and dilaton \phi recently obtained as the reduction to four-dimensions of the six-dimensional Salam-Sezgin model. In this latter case they provide the most general supersymmetric solution. Passing to the Riemannian formulation of this theory we show that the most general supersymmetric solution may be constructed starting from a self-dual Yang-Mills connection on a self-dual metric and solving a Poisson equation for e^\phi. We also present the generalization of these solutions to non-Abelian AdS pp-waves which allow a negative cosmological constant and preserve 1/4 of supersymmetry.Comment: Latex, 1+12 page

    SOCIAL CHANGE, ADULT EDUCATION AND SOCIOLOGY

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    Adult education has gained importance recently as a type of education which is different from formal education in terms of learning, teaching and program contents. When examined in the historical process with its content and programs, it is observed that adult education is shaped by the economic, social and political conditions. Contents and programs that change over time also differ among societies in line with their own conditions and needs. The rapid change of adult education's content in accordance with social conditions makes it inevitable to consider adult education from a sociological perspective. Moreover, adult education contents and programs provide important data in order to monitor social change and prior economic and social needs of different eras. On the other hand, determining the planning of adult education, its programs, target audience and educational contents by economic, social and political conditions strengthens the link between adult education and sociology. Especially using the opportunities of sociology in the planning of educational contents, target audience and training will strengthen the effect of adult education. This study aims to look at the the historical background of adult education sociologically and discuss the contribution that sociology's current opportunities can provide adult education. © 2021. All Rights Reserved

    Adaptive pairs trading strategy performance in Turkish derivatives exchange with the companies listed on Istanbul stock exchange

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    Due to copyright restrictions, the access to the full text of this article is only available via subscription.We implemented model-driven statistical arbitrage strategies in Turkish equities market. Trading signals are generated by optimized parameters of distance method. When the trade in signal is triggered by the model, market-neutral portfolio is created by long in the synthetic ETF, which is based on constrained least squares regression of selected Istanbul Stock Exchange stocks and short in Turkish Derivatives Exchange (Turkdex) index futures contract. We performed pairs trading strategy based on a comparative mean reversion of asset prices with daily data over the period February 2005 through July 2011 in Istanbul Stock Exchange (ISE) and Turkdex. We constructed a hypothetical ISE30 ETF Index on a daily basis in order to originate pairs trading strategy with Turkdex. Because of the leverage rule of (1–10) index futures contracts, we had to evaluate spot stock pairs formation with futures contracts pairs strategy. The results indicate that applied pairs strategy produced overall returns of 901 per cent during the investment period, whereas naive strategy (buy and hold ISE-30 index) return for the same period was 111 per cent. Similar outperformance was observed in the Sharpe and Sortino ratios

    The unique coclique extension property for apartments of buildings

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    We show that the Kneser graph of objects of a fixed type in a building of spherical type has the unique coclique extension property when the corresponding representation has minuscule weight and also when the diagram is simply laced and the representation is adjoint

    Determination of acrylamide in three different bread types by an in-house validated LC-MS/MS method

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    A rapid and reliable liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) method was developed for the determination of acrylamide in three different local bread types; wheat bread, bran bread, whole wheat bread. Acrylamide analyses were made in crust parts of the 85 bread samples. The method was linear up to 750 μg kg–1 food with a determination coeffi cient of 0.999. Recovery rate was found 99.3% with limit of detection and limit of quantifi cation values of 1.5 μg kg–1 and 5.0 μg kg–1, respectively. Certifi ed reference materials of crisp bread were analysed and acrylamide contents of these samples were found in the range cited in the certifi cates. Statistical correlations were investigated between acrylamide contents and protein contents, reducing sugar contents, moisture contents, pH, and colour parameters (L*, a*, b*) of bread samples. Sample preparation procedure and chromatographic conditions of acrylamide analysis were investigated in more detail, and a rapid, accurate, precise, and reliable analysis method was developed

    Spatial Distribution of the Incompressible Strips at Aharonov-Bohm Interferometer

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    In this work, the edge physics of an Aharonov-Bohm interferometer (ABI) defined on a two dimensional electron gas, subject to strong perpendicular magnetic field B, is investigated. We solve the three dimensional Poisson equation using numerical techniques starting from the crystal growth parameters and surface image of the sample. The potential profiles of etched and gate defined geometries are compared and it is found that the etching yields a steeper landscape. The spatial distribution of the incompressible strips is investigated as a function of the gate voltage and applied magnetic field, where the imposed current is confined to. AB interference is investigated due to scattering processes between two incompressible "edge-states".Comment: 5 pages, 3 figure
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