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Fabris J.C.,Federal University of Espirito Santo | Marques G.T.,Federal Rural University of Amazonia
European Physical Journal C | Year: 2012

The d-dimensional scalar field action may be reduced, in the background geometry of a black hole, to a two-dimensional effective action. In the near-horizon region, it appears a gravitational anomaly: the energy-momentum tensor of the scalar field is not conserved anymore. This anomaly is removed by introducing a term related to the Hawking temperature of the black hole. Even if the temperature term introduced is not covariant, a gauge transformation may restore the covariance. We apply this method to compute the temperature of the dilatonic non-asymptotically flat black holes. We compare the results with those obtained through other methods. © 2012 Springer-Verlag Berlin Heidelberg and Società Italiana di Fisica. Source


Marques G.T.,Federal Rural University of Amazonia | Rodrigues M.E.,Federal University of Espirito Santo
European Physical Journal C | Year: 2012

The conformal invariance of the Hawking temperature, conjectured for the asymptotically flat and stationary black holes by Jacobson and Kang, is semiclassically evaluated for a simple particular case of symmetrical spherically and non-asymptotically flat black hole. By using the Bogoliubov coefficients, the metric euclideanization, the reflection coefficient and the gravitational anomaly, as methods of calculating the Hawking temperature, we find that it is invariant under a specific conformal transformation of the metric. We briefly discuss the results for each method. © Springer-Verlag / Società Italiana di Fisica 2012. Source


De Souza Braz A.M.,University of Sao Paulo | Fernandes A.R.,Federal Rural University of Amazonia | Alleoni L.R.F.,University of Sao Paulo
Land Degradation and Development | Year: 2013

The conversion from forest to grassland is drastically changing soil characteristics in Amazon, leading to land degradation when it is poorly managed. Chemical and physical changes of a Typic Hapludox were evaluated as a function of the conversion (by means of fire) from forest to Brachiaria brizantha cultivation. Samples from the remaining forest were also sampled. Treatments were made to pastures eight (P8), thirteen (P13) and fifteen (P15) years after conversion, and to land under continuous grazing, and to a remaining forest area (control). The forest soil was more acidic than the pasture soils. Soil density and Ca+2 increased after the conversion, regardless of the period of grazing. Carbon stocks varied from 31·2tha-1 in the forest soil to 37·4 (P8), 33·5 (P13) and 30·7tha-1 (P15). Copyright © 2011 John Wiley & Sons, Ltd. © 2011 John Wiley & Sons, Ltd. Source


Garcia A.M.,Grande Rio University | Vieira J.P.,Grande Rio University | Winemiller K.O.,Texas A&M University | Moraes L.E.,Grande Rio University | Paes E.T.,Federal Rural University of Amazonia
Marine Ecology Progress Series | Year: 2012

We employed a new approach linking multivariate and time series analyses to identify common versus unique spatiotemporal components of abundance variation of marine spawning fishes recruiting into a subtropical Western Atlantic estuary. Based on a 10 yr standardized monthly data set, we also investigated patterns of association for local and regional factors with annual and inter-annual variation in abundance of 5 dominant marine estuarine-dependent fishes. The total amount of variation in fish abundance explained by environmental variables was 22.4%. After factoring out shared spatiotemporal variation (0.8%), our analysis showed that temporal components had an almost 5-fold greater contribution (28.0%) than spatial components (6.4%) in explaining the variation in abundance of the 5 species. Most of the variation across the temporal scale (58.5%) was associated with annual (from 0.5 to 1.3 yr) rather than multi-year oscillations (>2 yr). Such annual patterns were probably associated with adaptations of marine estuarine- dependent fishes for exploiting predictable pulses in seasonal productivity typically found in subtropical estuaries. In contrast, inter-annual variation in abundance occurring at a scale of 3 to 7 yr could be attributed to rainfall anomalies associated with El Niño Southern Oscillation (ENSO) events, whereas those occurring at a scale of 2 yr could be influenced by the Southern Annular Mode (SAM). Our findings corroborate the hypothesis that prevalent annual patterns of variation in the abundance of marine estuarine-dependent fishes are associated with predictable productivity pulses linked to the annual temperature regime, whereas inter-annual variations in fish abundance are associated with the influence of large-scale climatic phenomena. © Inter-Research 2012 · www.int-res.com. Source


Barbieri E.,Institute Pesca APTA SAA SP | Paes E.T.,Federal Rural University of Amazonia
Chemosphere | Year: 2011

The main purpose of the present study was to detect the acute toxicity of cadmium (Cd) in F. paulensis and to investigate its effect on oxygen consumption and ammonium excretion different salinities. First, we examined the acute toxicity of Cd in F. paulensis at 24, 48, 72, and 96-h lethal concentration (LC50). Cd was significantly more toxic at 5 salinity than at 20 and 36. The oxygen consumption and ammonium excretion were estimated through experiments performed on each of the twelve possible combinations of three salinities (36, 20 and 5), at temperature 20°C. Cd showed a reduction in oxygen consumption at 5 salinity, the results show that the oxygen consumption decreases with respect to the Cd concentration. At the highest Cd concentration employed (2mgL-1), the salinity 5 and the temperature at 20°C, oxygen consumption decreases 53.7% in relation to the control. In addition, after separate exposure to Cd, elevation in ammonium excretion was obtained, wish were 72%, 65% and 95% higher than the control, respectively. The results show that Cd is more toxic to F. paulensis at lower salinities. © 2011 Elsevier Ltd. Source

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