6,100 research outputs found

    Funding the Future: Resources for Adolescent Reproductive and Sexual Health Programs in Developing Countries

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    Provides a directory of over 90 foundations, agencies, and organizations that support adolescent reproductive and sexual health related programs in developing countries, through direct and/or indirect financing, technical assistance, and information

    ENVIRONMENTAL AND ECONOMIC IMPACTS OF AGRICULTURAL POLICY REFORM: AN INTERREGIONAL COMPARISON

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    Mathematical programming results revealed that moving toward more flexible agricultural policies would generate substantial economic and environmental gains in a North Carolina diversified cropping region. But in a Washington-Idaho dryland grains region, only the use of relatively new and sometimes problematic alternative cropping systems permitted environmental and economic gains under policy reform. In both regions, a recoupling policy, which links government payments to resource-conserving farming practices, was needed to protect environmental quality when market prices for program crops were high.Agrichemical leaching, Agricultural policy, Alternative agriculture, Erosion, Mathematical programming, Agricultural and Food Policy,

    Mechanical On-Chip Microwave Circulator

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    Nonreciprocal circuit elements form an integral part of modern measurement and communication systems. Mathematically they require breaking of time-reversal symmetry, typically achieved using magnetic materials and more recently using the quantum Hall effect, parametric permittivity modulation or Josephson nonlinearities. Here, we demonstrate an on-chip magnetic-free circulator based on reservoir engineered optomechanical interactions. Directional circulation is achieved with controlled phase-sensitive interference of six distinct electro-mechanical signal conversion paths. The presented circulator is compact, its silicon-on-insulator platform is compatible with both superconducting qubits and silicon photonics, and its noise performance is close to the quantum limit. With a high dynamic range, a tunable bandwidth of up to 30 MHz and an in-situ reconfigurability as beam splitter or wavelength converter, it could pave the way for superconducting qubit processors with integrated and multiplexed on-chip signal processing and readout.Comment: References have been update

    Experimental demonstration of evanescent coupling from optical fibre tapers to photonic crystal waveguides

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    Experimental results demonstrating nearly complete mode-selective evanescent coupling to a photonic crystal waveguide from an optical fibre taper are presented. Codirectional coupling with 98% maximum power transfer to a photonic crystal waveguide of length 65 ÎĽm and with a coupling bandwidth of 20 nm is realised

    A review of the Genus Hyperalonia Rondani (Bombyliidae, Diptera) from South América

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    Surface Encapsulation for Low-Loss Silicon Photonics

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    Encapsulation layers are explored for passivating the surfaces of silicon to reduce optical absorption in the 1500-nm wavelength band. Surface-sensitive test structures consisting of microdisk resonators are fabricated for this purpose. Based on previous work in silicon photovoltaics, coatings of SiNx and SiO2 are applied under varying deposition and annealing conditions. A short dry thermal oxidation followed by a long high-temperature N2 anneal is found to be most effective at long-term encapsulation and reduction of interface absorption. Minimization of the optical loss is attributed to simultaneous reduction in sub-bandgap silicon surface states and hydrogen in the capping material.Comment: 4 pages, 3 figure

    Design of photonic crystal microcavities for cavity QED

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    We discuss the optimization of optical microcavity designs based on 2D photonic crystals for the purpose of strong coupling between the cavity field and a single neutral atom trapped within a hole. We present numerical predictions for the quality factors and mode volumes of localized defect modes as a function of geometric parameters, and discuss some experimental challenges related to the coupling of a defect cavity to gas-phase atoms.Comment: 12 pages, 16 figure
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