11,493 research outputs found

    A scientific forum on the Gulf of Mexico: The Islands in the Stream Concept. Proceedings of the Forum: 23 January 2008, Keating Education Center, Mote Marine Laboratory, Sarasota, Florida

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    The Scientific Forum on the Gulf of Mexico: The Islands in the Stream Concept took place in January 2008 in Sarasota, Florida. The purpose of the meeting was to bring together scientists and managers from around the Gulf of Mexico to discuss a range of topics on our knowledge of the Gulf of Mexico, from its geology to larger-scale connectivity to the Caribbean region, and their applications to the concept of a more integrated approach to area-based management. The forum included six panels of invited experts who spoke on the oceanographic and biological features in the Gulf of Mexico, including connections with Mexico and the Mesoamerican barrier reef system, and the legal and regulatory structure currently in place. The charge to the group was to share information, identify gaps in our knowledge, identify additional potential areas for protection, and discuss available science about connectivity and the potential value of establishing a marine protected area network in the Gulf of Mexico. (PDF has 108 pages.

    Possible evidence of a spontaneous spin-polarization in mesoscopic 2D electron systems

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    We have experimentally studied the non-equilibrium transport in low-density clean 2D electron systems at mesoscopic length scales. At zero magnetic field (B), a double-peak structure in the non-linear conductance was observed close to the Fermi energy in the localized regime. From the behavior of these peaks at non-zero B, we could associate them to the opposite spin states of the system, indicating a spontaneous spin polarization at B = 0. Detailed temperature and disorder dependence of the structure shows that such a splitting is a ground state property of the low-density 2D systems.Comment: 7 pages, 5 figure

    Giant Fluctuations of Coulomb Drag in a Bilayer System

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    We have observed reproducible fluctuations of the Coulomb drag, both as a function of magnetic field and electron concentration, which are a manifestation of quantum interference of electrons in the layers. At low temperatures the fluctuations exceed the average drag, giving rise to random changes of the sign of the drag. The fluctuations are found to be much larger than previously expected, and we propose a model which explains their enhancement by considering fluctuations of local electron properties.Comment: 10 pages, 4 figure

    Positive state mindfulness: A multidimensional model of mindfulness in relation to positive experience

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    The present research tested Langer’s theory of mindfulness in the context of positive experiences: positive state mindfulness. In Study 1 (N1 = 586, N2 = 415) confirmatory factor analyses indicated that a three-factor model (Focused Attention, Novelty Appreciation, Open-Ended Expectations) fit the data well and explained responses better than a one-factor model. In support of construct validity, Study 2 (N3 = 239, N4 = 126) suggested that each dimension had a different pattern of associations with unidimensional trait measures of mindfulness, savoring beliefs, trait absorption, uncertainty tolerance, need for structure, and need for cognition. Study 3 (N5 = 46) revealed that each dimension correlated uniquely with the positive affect, self-esteem, interpersonal connectedness, and the overall rehearsal frequency associated with positive autobiographical events. In support of criterion validity in Study 4, in Experiment 1 (N6 = 46) a boredom task decreased Novelty Appreciation, and in Experiment 2 (N7 = 92) a problem-solving task increased Focused Attention. Our data suggest that positive mindfulness is more than the absence of mindlessness and that it includes three distinct dimensions. We discuss the utility of positive mindfulness in both research and practice

    Surface-acoustic-wave driven planar light-emitting device

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    Electroluminescence emission controlled by means of surface acoustic waves (SAWs) in planar light-emitting diodes (pLEDs) is demonstrated. Interdigital transducers for SAW generation were integrated onto pLEDs fabricated following the scheme which we have recently developed. Current-voltage, light-voltage and photoluminescence characteristics are presented at cryogenic temperatures. We argue that this scheme represents a valuable building block for advanced optoelectronic architectures

    Surface acoustic wave-induced electroluminescence intensity oscillation in planar light-emitting devices

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    Electroluminescence emission from surface acoustic wave-driven light-emitting diodes (SAWLEDs) is studied by means of time-resolved techniques. We show that the intensity of the SAW-induced electroluminescence is modulated at the SAW frequency (~1 GHz), demonstrating electron injection into the p-type region synchronous with the SAW wavefronts.Comment: 4 pages, 3 figure

    Quantum key distribution using a triggered quantum dot source emitting near 1.3 microns

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    We report the distribution of a cryptographic key, secure from photon number splitting attacks, over 35 km of optical fiber using single photons from an InAs quantum dot emitting ~1.3 microns in a pillar microcavity. Using below GaAs-bandgap optical excitation, we demonstrate suppression of multiphoton emission to 10% of the Poissonian level without detector dark count subtraction. The source is incorporated into a phase encoded interferometric scheme implementing the BB84 protocol for key distribution over standard telecommunication optical fiber. We show a transmission distance advantage over that possible with (length-optimized) uniform intensity weak coherent pulses at 1310 nm in the same system.Comment: 4 pages, 4 figure
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