14,820 research outputs found

    Adaptation Effectiveness and Free-Riding Incentives in International Environmental Agreements

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    While an international agreement over the reduction of greenhouse gases (GHGs) emissions proves to be elusive, there is a large and growing support for investment in developing more effective technologies to adapt to climate change. We show that an increase in effectiveness of adaptation will diminish the incentive of individual countries to free-ride on a global agreement over emissions. Moreover, we show that this positive effect of an increase in adaptation's effectiveness can also be accompanied by an increase in the gains from global cooperation over GHGs emissions.adaptation;climate change;international environmental agreements;transboundary pollution

    Observational constraints on interstellar dust models

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    No single model has been able to account for all of the observed spectroscopic properties of interstellar or circumstellar dust. The reason for this is that, despite the agreement that the grains are composed of silicaceous/metal oxide and carbonaceous material, there is strong disagreement as to their exact structure and composition. This led Draine and Lee (1984) to use interstellar extinction data to define an interstellar graphitic material; new observational findings have made even that identification uncertain. But the great advantage of their approach is that they used observations at all of the wavelengths available to define the material. Here, the authors attempt a variation of that approach. They examine recent UV and IR data and attempt to put constraints on the possible types of interstellar grain composition, and to connect these constraints with grain models. A summary of some of the important constraints imposed by the observations is given

    Si3N4 emissivity and the unidentified infrared bands

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    Infrared spectroscopy of warm (about 150 to 750 K), dusty astronomical sources has revealed a structured emission spectrum which can be diagnostic of the composition, temperature, and in some cases, even size and shape of the grains giving rise to the observed emission. The identifications of silicate emission in oxygen rich objects and SiC in carbon rich object are two examples of this type of analysis. Cometary spectra at moderate resolution have similarly revealed silicate emission, tying together interstellar and interplanetary dust. However, Goebel has pointed out that some astronomical sources appear to contain a different type of dust which results in a qualitatively different spectral shape in the 8 to 13 micron region. The spectra shown make it appear unlikely that silicon nitride can be identified as the source of the 8 to 13 micron emission in either NGC 6572 or Nova Aql 1982. The similarity between the general wavelength and shape of the 10 micron emission from some silicates and that from the two forms of silicon nitride reported could allow a mix of cosmic grains which include some silicon nitride if only the 8 to 13 micron data are considered

    Implementation of ILLIAC 4 algorithms for multispectral image interpretation

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    Research has focused on the design and partial implementation of a comprehensive ILLIAC software system for computer-assisted interpretation of multispectral earth resources data such as that now collected by the Earth Resources Technology Satellite. Research suggests generally that the ILLIAC 4 should be as much as two orders of magnitude more cost effective than serial processing computers for digital interpretation of ERTS imagery via multivariate statistical classification techniques. The potential of the ARPA Network as a mechanism for interfacing geographically-dispersed users to an ILLIAC 4 image processing facility is discussed

    Performance characteristics of an electromagnetic pump

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    The linear induction pump (76 laminations, 0.125-inch duct thickness, 0.319-inch air gap) can produce a maximum no-flow pressure of 0.734 psi and can pump 0.450 gpm against a 0.2 psi head. With an air gap of 0.443 inch and a pump section having a 0.250-inch duct thickness, the maximum no-flow pressure decreases to 0.551 psi, but the improved hydraulic efficiency of the larger duct permits circulation of 0.9 gpm against a 0.2 psi head. The improvement in magnetic field strength from 78 gauss/amp at 0.443 inch air gap to 103 gauss/amp at 0.310 inch air gap indicates the need for minimizing the pump air gap while maintaining a duct thickness consistent with good hydraulic efficiency

    Fluxoid formation: size effects and non-equilibrium universality

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    Simple causal arguments put forward by Kibble and Zurek suggest that the scaling behaviour of condensed matter at continuous transitions is related to the familiar universality classes of the systems at quasi-equilibrium. Although proposed 25 years ago or more, it is only in the last few years that it has been possible to devise experiments from which scaling exponents can be determined and in which this scenario can be tested. In previous work, an unusually high Kibble-Zurek scaling exponent was reported for spontaneous fluxoid production in a single isolated superconducting Nb loop, albeit with low density. Using analytic approximations backed up by Langevin simulations, we argue that densities as small as these are too low to be attributable to scaling, and are conditioned by the small size of the loop. We also reflect on the physical differences between slow quenches and small rings, and derive some criteria for these differences, noting that recent work on slow quenches does not adequately explain the anomalous behaviour seen here.Comment: 7 pages, 4 figures, presentation given at CMMP 201
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