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 $Z'$ boson. This enlarged SM is coupled to a dark matter sector through the Stueckelberg mechanism by a $A'$ boson. However, the $A'$ boson does not interact directly with the SM fermions. In our study, we found that the $A'$ is a massless photon-like particle in dark sector. Constraints on the mass for $Z'$ and corrections to $Z$ 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