Using a laser aureole to invert lidar return

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

Metered oxygen supply aids treatment of domestic sewage

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

Some Comments on an MeV Cold Dark Matter Scenario

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

New ⁴⁰Ar/³⁹Ar dating of the Grande Ronde lavas, Columbia River Basalts, USA: Implications for duration of flood basalt eruption episodes

Grande Ronde Basalt (GRB) lavas represent the most voluminous eruptive pulse of the Columbia River-Snake River-Yellowstone hotspot volcanism. With an estimated eruptive volume of 150,000 km3, GRB lavas form at least 66% of the total volume of the Columbia River Basalt Group. New 40Ar/39Ar dates for GRB lavas reveal they were emplaced within a maximum period of 0.42 ± 0.18 My. A well-documented stratigraphy indicates at least 110 GRB flow fields (or individual eruptions), and on this basis suggests an average inter-eruption hiatus of less than 4,000 years. Isotopic age-dating cannot resolve time gaps between GRB eruptions, and it is difficult to otherwise form a picture of the durations of eruptions because of non-uniform weathering in the top of flow fields and a general paucity of sediments between GR lavas. Where sediment has formed on top of the GRB, it varies in thickness from zero to 20-30 cm of silty to fine-sandy material, with occasional diatomaceous sediment. Individual GRB eruptions varied considerably in volume but many were greater than 1000 km3 in size. Most probably eruptive events were not equally spaced in time; some eruptions may have followed short periods of volcanic repose (perhaps 102 to 103 of yrs), whilst others could have been considerably longer (many 1000 s to > 104 yrs). Recent improvements in age-dating for other continental flood basalt (CFB) lava sequences have yielded estimates of total eruptive durations of less than 1 My for high-volume pulses of lava production. The GRB appears to be a similar example, where the main pulse occupied a brief period. Even allowing for moderate to long-duration pahoehoe flow field production, the amount of time the system spends in active lava-producing mode is small – less than c. 2.6% (based on eruption durations of approximately 10,000 yrs, as compared to the duration of the entire eruptive pulse of c. 420,000 yrs). A review of available 40Ar/39Ar data for the major voluminous phases of the Columbia River Basalt Group suggests that activity of the Steens Basalt-Imnaha Basalt-GRB may have, at times, been simultaneous, with obvious implications for climatic effects. Resolving intervals between successive eruptions during CFB province construction, and durations of main eruptive pulses, remains vital to determining the environmental impact of these huge eruptions

Extended MSSM Neutralinos as the Source of the PAMELA Positron Excess

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

Prospects For Detecting Dark Matter With Neutrino Telescopes In Light Of Recent Results From Direct Detection Experiments

Direct detection dark matter experiments, lead by the CDMS collaboration, have placed increasingly stronger constraints on the cross sections for elastic scattering of WIMPs on nucleons. These results impact the prospects for the indirect detection of dark matter using neutrino telescopes. With this in mind, we revisit the prospects for detecting neutrinos produced by the annihilation of WIMPs in the Sun. We find that the latest bounds do not seriously limit the models most accessible to next generation kilometer-scale neutrino telescopes such as IceCube. This is largely due to the fact that models with significant spin-dependent couplings to protons are the least constrained and, at the same time, the most promising because of the efficient capture of WIMPs in the Sun. We identify models where dark matter particles are beyond the reach of any planned direct detection experiments while within reach of neutrino telescopes. In summary, we find that, even when contemplating recent direct detection results, neutrino telescopes still have the opportunity to play an important as well as complementary role in the search for particle dark matter.Comment: 13 pages, 6 figure

Quantum molecular dynamics simulations of the oxidation of aluminum-cyclopentadienyl clusters

The article of record as published may be located at http://dx.doi.org/10.1088/1742-6596/500/17/172001We report Car-Parrinello molecular dynamics simulations of the oxidation of aluminum-cyclopentadienyl clusters currently being considered as novel fuels or energetic materials. These clusters contain a small aluminum core surrounded by a single organic ligand layer. The aromatic cyclopentadienyl ligands form a very strong bond with surface Al atoms, giving rise to a stable organometallic cluster which crystallizes into a low-symmetry solid-state material. Our calculations of an isolated cluster in oxygen show minimal reaction between the ligand and oxygen molecules at simulation temperatures of 300 and 1000 K. Rather, in all cases O2 diffuses through the ligand barrier, splits into atomic oxygen upon contact with the aluminum, and forms an amorphous aluminum oxide core. Loss of aluminum-ligand units, as expected from bond strength calculations, is not observed except following significant oxidation. We present simple metrics to quantitatively compare the steric barrier of the outer ligands that limits the oxidation process.This work was funded by the Office of Naval Research