2,403 research outputs found

    Directional optical switching and transistor functionality using optical parametric oscillation in a spinor polariton fluid

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    Over the past decade, spontaneously emerging patterns in the density of polaritons in semiconductor microcavities were found to be a promising candidate for all-optical switching. But recent approaches were mostly restricted to scalar fields, did not benefit from the polariton's unique spin-dependent properties, and utilized switching based on hexagon far-field patterns with 60{\deg} beam switching (i.e. in the far field the beam propagation direction is switched by 60{\deg}). Since hexagon far-field patterns are challenging, we present here an approach for a linearly polarized spinor field, that allows for a transistor-like (e.g., crucial for cascadability) orthogonal beam switching, i.e. in the far field the beam is switched by 90{\deg}. We show that switching specifications such as amplification and speed can be adjusted using only optical means

    Optimising environmental product life cycles: A case study of the European pulp and paper sector

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    In this paper, we propose a methodology, based on materials accounting and operational research techniques, to assess different industry configurations according to their life cycle environmental impacts. Rather than evaluating a specific technology, our methodology searches for the feasible configuration with the minimum impact. This approach allows us to address some basic policy-relevant questions regarding technology choice, investment priorities, industrial structures, and international trade patterns. We demonstrate the methodology in the context of the European pulp and paper industry. We are able to show that current environmental policy's focus on maximising recycling is optimal now, but that modest improvements in primary pulping technology may shift the optimal industry configuration away from recycling toward more primary pulping with incineration. We show that this will have significant implications for the amount and type of environmental damage, for the location of different stages in the production chain, and for trade between European member states. We caution policy makers that their single-minded focus on recycling may foreclose investment in technologies that could prove environmentally superior. Finally, we hint that member state governments may be fashioning their environmental policy positions at least in part on some of the trade and industrial implications we find

    Two-Channel Kondo Lattice: An Incoherent Metal

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    The two-channel Kondo lattice model is examined with a Quantum Monte Carlo simulation in the limit of infinite dimensions. We find non-fermi-liquid behavior at low temperatures including a finite low-temperature single-particle scattering rate, the lack of a fermi edge and Drude weight. However, the low-energy density of electronic states is finite. Thus, we identify this system as an incoherent metal. We discuss the relevance of our results for concentrated heavy fermion metals with non-Fermi-Liquid behavior.Comment: LaTex, 5 pages, 3 Postscript files. Revision - in reference 5 and 6(a

    A sensitive and specific antigen detection assay for Middle East respiratory syndrome coronavirus

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    Near Sharp Strichartz estimates with loss in the presence of degenerate hyperbolic trapping

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    We consider an nn-dimensional spherically symmetric, asymptotically Euclidean manifold with two ends and a codimension 1 trapped set which is degenerately hyperbolic. By separating variables and constructing a semiclassical parametrix for a time scale polynomially beyond Ehrenfest time, we show that solutions to the linear Schr\"odiner equation with initial conditions localized on a spherical harmonic satisfy Strichartz estimates with a loss depending only on the dimension nn and independent of the degeneracy. The Strichartz estimates are sharp up to an arbitrary β>0\beta>0 loss. This is in contrast to \cite{ChWu-lsm}, where it is shown that solutions satisfy a sharp local smoothing estimate with loss depending only on the degeneracy of the trapped set, independent of the dimension

    Phase Diagram of the Two-Channel Kondo Lattice

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    The phase diagram of the two-channel Kondo lattice model is examined with a Quantum Monte Carlo simulation in the limit of infinite dimensions. Commensurate (and incommensurate) antiferromagnetic and superconducting states are found. The antiferromagnetic transition is very weak and continuous; whereas the superconducting transition is discontinuous to an odd-frequency channel-singlet and spin-singlet pairing state.Comment: 5 pages, LaTeX and 4 PS figures (see also cond-mat/9609146 and cond-mat/9605109
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