10,682 research outputs found
Microwave brightness of polar firn as measured by Nimbus 5 and 6 ESMR
The microwave emission from a half-space medium characterized by coordinate dependent scattering and absorbing centers was calculated by numerically solving the radiative transfer equation by the method of invariant imbedding. A Mie scattering phase function and surface polarization was included in the calculation. Also included are the physical temperature profile and the temperature variation of the index of refraction for ice. Using published values of grain size and temperature profile data of polar firn, the brightness temperature was calculated for the 1.55 cm and 0.8 cm wavelengths. For selected regions in Greenland and Antarctica, the results are in reasonable agreement with the observed Nimbus-5 and Nimbus-6 ESMR data
Unitarity constraints on the stabilized Randall-Sundrum scenario
Recently proposed stabilization mechanism of the Randall-Sundrum metric gives
rise to a scalar radion, which couples universally to matter with a weak
interaction ( TeV) scale. Demanding that gauge boson scattering as
described by the effective low enerrgy theory be unitary upto a given scale
leads to significant constraints on the mass of such a radion.Comment: 10 page Latex 2e file including 4 postscript figures. Accepted in
Journal of Physics
Ion-acoustic solitons in warm magnetoplasmas with super-thermal electrons
In this work, the phenomenon of formation of localised electrostatic waves
(ESW) or soliton is considered in a warm magnetoplasma with the possibility of
non-thermal electron distribution. The parameter regime considered here is
relevant in case of magnetospheric plasmas. We show that deviation from a usual
relaxed Maxwellian distribution of the electron population has a significant
bearing in the allowed parameter regime, where these ESWs can be found. We
further consider the presence of more than one electron temperature, which is
inspired by recent space-based observations[key-2].Comment: 10 pages, 5 figure
Silicon materials task of the low cost solar array project. Phase 3: Effect of impurities and processing on silicon solar cells
The 13th quarterly report of a study entitled an Investigation of the Effects of Impurities and Processing on Silicon Solar Cells is given. The objective of the program is to define the effects of impurities, various thermochemical processes and any impurity-process interactions on the performance of terrestrial silicon solar cells. The Phase 3 program effort falls in five areas: (1) cell processing studies; (2) completion of the data base and impurity-performance modeling for n-base cells; (3) extension of p-base studies to include contaminants likely to be introduced during silicon production, refining or crystal growth; (4) anisotropy effects; and (5) a preliminary study of the permanence of impurity effects in silicon solar cells. The quarterly activities for this report focus on tasks (1), (3) and (4)
Spectator Effects in the Decay B -> K \gamma \gamma
We report the results of the first computation related to the study of the
spectator effects in the rare decay mode within the
framework of Standard Model. It is found that the account of these effects
results in the enhancement factor for the short-distance reducible contribution
to the branching ratio.Comment: 5 pages, 5 figures, RevTeX
Inverting nutrient fluxes across the land-water interface - Exploring the potential of zebra mussel (Dreissena polymorpha) farming
We studied the potential of zebra mussel farming for nutrient retention in a eutrophic lake. Duplicate experimental long-line cultivation units were deployed and mussel growth and nutrient retention were quantified after 28 months. Mussels grew well at shallow water depth (<3 m) and our 625 m(2) (lake area) experimental units produced 507 and 730 kg dry biomass, respectively, of which 94% were shells. These yields corresponded to an average retention of 92.7 +/- 23.1 kg C, 6.1 +/- 0.68 kg N, and 0.43 +/- 0.04 kg P retention, or 742 kg C, 49 kg N, and 3.5 kg P for a full-size (0.5 ha) mussel farm. We estimate that concentrating the long-lines to a depth of 2.5 m would probably have doubled these yields, based on the differences in mussel growth among depths. We further estimate that a full-size cultivation unit (0.5 ha) thus could compensate for the annual total-P run-off from 23 ha, or the biologically available P from approximately 49 ha of agricultural soils. As traditional measures have proven insufficient, decision-makers need to facilitate novel approaches to mitigate the negative effects of cultural eutrophication. We envision that zebra mussel farming, within their invaded range, provides a promising approach to invert nutrient losses in lakes and coastal lagoons
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