41,208 research outputs found
Natural waters in Amazonia. III. Ammonium molybdate-reactive silica
Natural waters of the Amazonian Tertiary formations along the Manaus-Itacoatjara Road were studied with respect to variations in average seasonal and yearly soluble silica content. In general the variations are small and concentrations very low, for all input fractions, i. e., rainfall, stemflow, and throughfall [about 90 percent of the total (470 analyses) lower than 1.0 mg/l]. While 90 percent of total ground water analyses (excluding well IV 3) have soluble silica concentrations lower than 1.5 mg/l, high rain forest stream waters are slightly higher (90 percent of all values lower than 2.0 mg/l). The Rio Negro waters show 90 percent of the total samples analyzed between 2.0 mg/l and 3.0 mg/l soluble silica
Searching for a dark matter coupling to the Standard Model with a Stueckelberg extension
We investigate a double extension to the Standard Model (SM). A first
extension introduces, via minimal coupling, a massive boson. This enlarged
SM is coupled to a dark matter sector through the Stueckelberg mechanism by a
boson. However, the boson does not interact directly with the SM
fermions. In our study, we found that the is a massless photon-like
particle in dark sector. Constraints on the mass for and corrections to
mass are obtained.Comment: Presented at IWARA 2011. "Fifth International Workshop on Astronomy
and Relativistic Astrophysics" Jo\~ao Pessoa, Brazil, October 9 to 12, 201
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