31,405 research outputs found

    Bright Water- hydrosols, water conservation and climate change

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    Since air-water and water-air interfaces are equally refractive, cloud droplets and microbubbles dispersed in bodies of water reflect sunlight in much the same way. The lifetime of sunlight-reflecting microbubbles, and hence the scale on which they may be applied, depends on Stokes Law and the influence of ambient or added surfactants. Small bubbles backscatter light more efficiently than large ones, opening the possibility of using highly dilute micron-radius hydrosols to substantially brighten surface waters. Such microbubbles can noticeably increase water surface reflectivity, even at volume fractions of parts per million and such loadings can be created at an energy cost as low as J m-2 to initiate and milliwatts m-2 to sustain. Increasing water albedo in this way can reduce solar energy absorption by as much as 100 W m-2, potentially reducing equilibrium temperatures of standing water bodies by several Kelvins. While aerosols injected into the stratosphere tend to alter climate globally, hydrosols can be used to modulate surface albedo, locally and reversibly, without risk of degrading the ozone layer or altering the color of the sky. The low energy cost of microbubbles suggests a new approach to solar radiation management in water conservation and geoengineering: Don't dim the Sun; Brighten the water.Comment: 15 pages, Presented at The Asilomar Confernce on Climate Intervention technologie

    Detection of Dark Matter Concentrations in the Field of Cl 1604+4304 from Weak Lensing Analysis

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    We present a weak-lensing analysis of a region around the galaxy cluster Cl 1604+4304 (z=0.897) on the basis of the deep observations with the HST/WFPC2. We apply a variant of Schneider's aperture mass technique to the observed WFPC2 field and obtain the distribution of weak-lensing signal-to-noise (S/N) ratio within the field. The resulting S/N map reveals a clear pronounced peak located about 1.7 arcmin (850h_{50}^{-1} kpc at z=0.897) southwest of the second peak associated with the optical cluster center determined from the dynamical analysis of Postman et al. A non-linear finite-field inversion method has been used to reconstruct the projected mass distribution from the observed shear field. The reconstructed mass map shows a super-critical feature at the location of the S/N peak as well as in the cluster central region. Assuming the redshift distribution of field galaxies, we obtain the total mass in the observed field to be 1.0 h_{50}^{-1} 10^{15} M_sun for =1.0. The estimated mass within a circular aperture of radius 280h_{50}^{-1} kpc centered on the dark clump is 2.4h_{50}^{-1} 10^{14} M_sun. We have confirmed the existence of the ` dark ' mass concentration from another deep HST observation with a slightly different ~20 arcsec pointing.Comment: 7 pages, 3 figure

    Subnational government bailouts in Germany

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    The paper presents an investigation of subnational government bailouts in Germany. In a first part we briefly describe the fiscal federalism system in Germany. The main part of the paper examines the bailout of two West German states. We identify the causes of the financial trouble of both states and examine the institutional settings that forced the federal government to provide bailout transfers. In addition, we investigate the impact these transfers had on the fiscal performance of both LĂ€nder. In a further section we provide evidence on bailouts of local governments by the German LĂ€nder. A final section summarizes our results and presents policy conclusions. --

    The Gains from Variety in the European Union

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    Over the last decade, European Union members have experienced a dramatic increase in imports. This increase was accompanied by a strong growth in the number of imported goods and trading partners, indicating positive welfare gains for consumers via an extended set of consumption possibilities, as pointed out in the "New Trade Theory". In this paper, we apply the methodology developed by Feenstra (1994) and Broda and Weinstein (2006) to estimate structurally the gains from imported variety for the 27 countries of the European Union using highly disaggregated trade data at the HTS-8 level from Eurostat for the period of 1999 to 2008. Our results show that, within the European Union, especially “newer” and smaller member states exhibit high gains from newly imported varieties. Furthermore, we find that the vast majority of the gains from variety for consumers stem from intra-European Union trade

    Subnational Bailouts in Germany

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    This paper presents an investigation of subnational government bailouts in Germany. In the first part we briefly describe the system of fiscal federalism in Germany. The main part of the paper examines the bailout of two West German states. We identify the causes of the financial crisis in both states and examine the institutional settings as well as the ruling of the Constitutional Court that forced the federal government to provide bailout transfers. In addition, we investigate the impact these transfers had on the fiscal performance of both states. In a further section we provide evidence on bailouts of local governments by German states. A final section summarizes our results and presents policy conclusions.

    Public capital and the demand for private inputs

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    The paper investigates the impact the provision of public capital has on the demand for private capital and labour using a cost function with public capital included as a fixed unpaid factor of production. Special attention is paid to the examination of the influence tax vs. debt financing of public investment might have on the demand for private capital. The model is applied to a panel of 31 2-digit industries of the West German manufacturing industry. It is shown, that private and public capital are complements whereas a substitutive relation emerges for labour and public capital. Decomposing the adjustment of the demand for private labour and capital reveals a stabilizing but steadily decreasing impact of public capital on private inputs. --
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