Federal University of São Carlos

About: Federal University of São Carlos is a education organization based out in São Carlos, Brazil. It is known for research contribution in the topics: Population & Microstructure. The organization has 16471 authors who have published 34057 publications receiving 456654 citations. The organization is also known as: UFSCar & Federal University of São Carlos.

A spatial correlation aware algorithm to perform efficient data collection in wireless sensor networks

Abstract: Large scale dense wireless sensor networks (WSNs) will be increasingly deployed in different classes of applications for accurate monitoring. Due to this high density of nodes, it is very likely that both spatially correlated information and redundant data can be detected by several nearby nodes, which can be exploited to save energy. In this work we consider the problem of constructing a spatial correlation aware dynamic and scalable routing structure for data collection and aggregation in WSNs. Although there are some solutions for data aggregation in WSNs, most of them build their structures based on the order of event occurrence. This can lead to both low quality routing trees and a lack of load balancing support, since the same tree is used throughout the network lifetime. To tackle these challenges we propose a novel algorithm called dYnamic and scalablE tree Aware of Spatial correlaTion (YEAST). Results show that the routing tree built by YEAST provides the best aggregation quality compared with other evaluated algorithms. With YEAST an event can be sensed with 97% accuracy, and 75% of the nodes' residual energy can be saved within the phenomena area when compared with the classical approach for data collection.

Occurrence of toxin-producing cyanobacteria blooms in a Brazilian semiarid reservoir

Abstract: Nos relatamos a ocorrencia de florescimentos de cianobacterias e a presenca de cianotoxinas em amostras de agua do reservatorio Armando Ribeiro Goncalves (06° 08’ S; 37° 07’ W) situado no Estado do Rio Grande do Norte, na regiao semi-arida do Brasil. Cianobacterias foram identificadas e quantificadas nos periodos seco e chuvoso do ano 2000. Cianotoxinas tais como, microcistinas, saxitoxinas e cilindrospermopsinas foram quantificadas por HPLC e ELISA. Florescimentos toxicos mistos de Cylindrospermopsis raciborskii, Microcystis spp (M. panniformis, M. protocystis, M. novacekii) e Aphanizomenon ssp (Aphanizomenon gracile, A. cf. manguinii, A. cf. issastschenkoi) foram persistentes e representaram 90-100% da comunidade fitoplanctonica ao longo do periodo estudado. No periodo de chuvas, florescimentos toxicos de Cylindrospermopsis raciborskii coincidiram com maiores valores de saxitoxinas (3,14 µg.L-1). Entre o periodo de chuva e estiagem, ocorreram florescimentos toxicos de Microcytis spp, excedendo o valor minimo aceitavel para consumo humano (8,8 µg.L-1). Na estiagem, baixas concentracoes de saxitoxinas foram detectadas em florescimentos menos intensos com co-dominância de Cylindrospermopsis raciborskii, Microcystis spp e Aphanizomenon spp. Nossos resultados revelaram a presenca de microcistinas (8,8 µg.L-1) e saxitoxinas (3,14 µg.L-1) na agua bruta, a partir da segunda quinzena de abril ate o final de maio de 2000. A ocorrencia de blooms toxicos de cianobacterias no reservatorio em estudo aponta um risco permanente de cianotoxinas em aguas de abastecimento e indica a necessidade da implementacao de medidas de controle das floracoes, visando a melhoria da qualidade da agua. A exposicao das populacoes locais as cianotoxinas, pela sua potencial acumulacao em musculatura de peixes, tambem deve ser considerada.

Antioxidant defenses and biochemical changes in pacu (Piaractus mesopotamicus) in response to single and combined copper and hypoxia exposure.

Abstract: The effect of combined-factors (hypoxia+copper) on the biochemical parameters and antioxidant defenses were studied in the neotropical fish Piaractus mesopotamicus. Fish were exposed for 48 h to 0.4 mg Cu(2+) L(-1) (0.4Cu), hypoxia=50 mm Hg (Hpx), and 0.4 mg Cu(2) L(-1)+hypoxia=50 mm Hg (0.4CuHpx). The exposure to 0.4Cu increased the reactive oxygen species (ROS) in the liver, accompanied by increases in superoxide dismutase (SOD) and decreases in catalase (CAT) activity, showing the influence of copper in this protection. The exposure to Hpx decreased the activity of glutathione peroxidase (GSH-Px) and CAT. Exposure to a combined-factor caused an increase in the ROS production followed by an increase in SOD and a decrease in GSH-Px and CAT. At 0.4Cu, fish presented a reduction in CAT, while in Hpx decreases in SOD, CAT and GSH-Px were observed in red muscles. Single-factors were insufficient to cause ROS production. In combined-factors, increased ROS formation and decreased SOD, CAT and GSH-Px were observed. RBC increased in all groups, but only under combined-factors was there an increase in hemoglobin. Copper plasma concentration increased in groups exposed to copper. Na(+)/K(+)-ATPase activity in gills decreased in 0.4Cu and 0.4CuHpx, and increased in Hpx. Metallothionein concentration in gills increased under combined-factors. Combined-factors caused significant disturbances in the antioxidant defenses and biochemical parameters than single-factors.

α - to - β transformation on PVDF films obtained by uniaxial stretch

Abstract: The α to β phase transformation of PVDF through the stretching process at different temperatures was investigated. The optimum stretching conditions were studied and characterised by infrared spectroscopy and differential scanning calorimetry. The maximum β−phase content was achieved at 80°C and a stretch ratio of 5. Accompanying the phase transformation, a orientation of the polymer chains and a packing of the crystalline structure is observed. The stretch ratio does not significantly affect the degree of crystallinity.