9,320 research outputs found

    Using a laser aureole to invert lidar return

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    An aureole generated by a laser beam was studied. The strength of the signal redirected towards a sensor high above the surface by a combination of one scattering event in the marine boundary layer (mbl) and one single reflection event from the ocean surface was estimated. A model of mbl aerosol size distributions was used to estimate Mie scattering for a wide range of meteorolocial conditions. The sea surface reflection was determined from a Gaussian model of the wave slopes. These laser aureoles which were estimated over the wide range of conditions and were normalized by the reflected laser light were found to be highly correlated with the optical depth of the boundary layer. By estimating optical depth from the aureole, the Bernoulli-Riccati inversion of lidar return could be constrained and the inversion accuracy improved. A Monte Carlo program was developed to study the laser aureole generated by up to 8 orders of reflection and scattering. The aureole was generated by a narrow, 10 nsec laser pulse at 1.06 microns and measured by a receiver 10 km above the ocean surface. The original theoretical computation compared well with the Monte Carlo method. When multiple scattereffects were included, the normalized aureole was still highly correlated with the mbl optical depth over the range of conditions

    Extended MSSM Neutralinos as the Source of the PAMELA Positron Excess

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    We consider a scenario within the Minimal Supersymmetric Standard Model extended by a singlet chiral superfield, in which neutralino dark matter annihilates to light singlet-like Higgs bosons, which proceed to decay to either electron-positron or muon-antimuon pairs. Unlike neutralino annihilations in the MSSM, this model can provide a good fit to the PAMELA cosmic ray positron fraction excess. Furthermore, the singlet-like scalar Higgs can induce a large Sommerfeld enhancement and provide an annihilation rate sufficient to accommodate the observed positron excess

    Metered oxygen supply aids treatment of domestic sewage

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    Microbiological fixed-bed process was developed in which supplementary oxygen required by microbial species is supplied by electrochemical device. Rate of addition of oxygen to waste treatment process is controlled to maintain aerobic metabolism and prevent anaerobic metabolisms which produce odorous or toxic products

    Review of animal health service delivery in the mixed crop-livestock system in Ethiopia

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    Some Comments on an MeV Cold Dark Matter Scenario

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    We discuss several aspects of astroparticle physics pertaining to a new model with MeV cold dark matter particles, which annihilate to electron-positron pairs in a manner yielding the correct CDM density required today, and explaining the enhanced electron-positron annihilation line from the center of the Galaxy. We note that the mass of the vector meson mediating the annihilations, should exceed the mass of CDM particle, and comment on possible enhancement due to CDM clustering, on the detectability of the new CDM, and on particle physics models incorporating this scenario.Comment: 13 pages, 2 figures. v2 - Added some remarks regarding a more stringent mass bound. References added, some typos corrected. v3 - Added a comment regarding the invalidity of perturbative calculation in the case of a very small coupling g'. Removed the comment regarding the smallness of the angular width of the 511 keV lin

    Recurrence in generic staircases

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    The straight-line flow on almost every staircase and on almost every square tiled staircase is recurrent. For almost every square tiled staircase the set of periodic orbits is dense in the phase space

    Integrated Water Resources Management and River Basin Governance

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    Covenant action to facilitate integrated river basin management

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    This paper outlines elements of best practice integrated river basin management and explores a procedure to implement IRBM. The procedure identifies a ‘road map’ for improved governance based on a best practice approach, with initial trialling in a UNESCO HELP basin in North America showing some application. But even with best practices understood, action is often only minimal and flexible, adaptable institutions are needed to underpin basin management. The covenant concept is one such institution, based on the idea of harnessing mutual trust and obligation between stakeholders. A covenant is ‘signed’ as a social contract and the idea of covenant described in this paper results from observations of intractable water sharing problems. This paper also outlines the components of a covenant, the factors which require consideration for implementation and ways forward.Keywords: covenants, mutual responsibility, integrated water resources management, basin governanc
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