46 research outputs found
<bold>The efficiency of electrocoagulation using aluminum electrodes</bold>i<bold>n treating wastewater from a dairy industry</bold>
Determinantes e conseqüências da insegurança alimentar no Amazonas: a influência dos ecossistemas
Collective Modes in Neutrino `Beam' Electron-Positron Plasma Interactions
We derive semiclassical neutrino-electron transport equations in the
collisionless (Vlasov) limit from the coupled Dirac equations, incorporating
the charged and neutral weak current-current as well as electromagnetic
interactions. A corresponding linear response theory is derived. In particular,
we calculate the response functions for a variety of beam-plasma geometries,
which are of interest in a supernova scenario. We apply this to the study of
plasmons and to a new class of collective {\it pharon} resonance modes, which
are characterized by . We find that the growth rates of the
unstable modes correspond to a strongly temperature ()
and linearly momentum dependent e-folding length of about km under
typical conditions for Type II supernovae. This appears to rule out such
long-wavelength collective modes as an efficient means of depositing neutrino
energy into the plasma sphere.Comment: 27 pages; LaTex. Replaced by published version. - Appendix about
neutrino Wigner functions added and main text correspondingly revised.
Conclusions unchange
Diet of two syntopic species of Crenuchidae (Ostariophysi: Characiformes) in an Amazonian rocky stream
Abstract This study assessed the diet of two poorly known syntopic fish species of the family Crenuchidae, Characidium aff. declivirostre and Leptocharacidium omospilus, in a Presidente Figueiredo´ rocky stream, Amazonas, Brazil. The stomach contents were analyzed and their Frequency of Occurrence (FO %) and Relative Volume (Vol %) were combined in a Feeding Index (IAi). We examined 20 individuals of C. aff. declivirostre and 23 of L. omospilus. The Morisita-Horn Index was used to estimate the overlap between the diets of these species. Immature insects were the most valuable items consumed by both fish species. The diet of C. aff. declivirostre was mainly composed of larvae and pupae of Chironomidae, while L. omospilus predominantly consumed larvae of Hydroptilidae, Hydropyschidae and Pyralidae. Thus, both species were classified as autochthonous insectivorous. Characidium aff. declivirostre was considered a more specialized species, probably reflecting lower feeding plasticity or the use of more restricted microhabitats compared to L. omospilus. When the food items were analyzed at the family taxonomic level, the diet overlap between these species was considered moderate (Morisita-Horn Index = 0.4). However, a more thorough analysis, at the genus level, indicates a very low diet overlap. Therefore, we conclude that the feeding segregation between C. aff. declivirostre and L. omospilus may favor their co-existence, despite their high phylogenetic closeness