| 1. |
- Borges Vieira, Alex, et al.
(författare)
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Modelo de Comportamento dos Participantes do SopCast
- 2009
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Ingår i: WebMedia 2009. - New York, NY, USA : ACM. - 9781605588803
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Konferensbidrag (refereegranskat)abstract
- Apesar da crescente popularidade das aplica¸c˜oes de transmiss ˜ao de m´ıdia cont´ınua ao vivo em P2P, a compreens˜ao atual de aspectos importantes do comportamento dos participantes, como o intervalo de chegada entre eles e tempo de permanˆencia na rede, ainda ´e limitada. Este trabalho pretende preencher esta lacuna apresentando uma caracteriza ¸c˜ao do comportamento dos participantes no SopCast, uma das aplica¸c˜oes mais populares de transmiss˜ao ao vivo sobre P2P. A an´alise apresentada inclui propriedades relativas `a sess˜ao, tais como intervalos entre chegada de novos participantes, tempo de permanˆencia, n´umero de sess˜oes q e tempo de inatividade entre sess˜oes. Tamb´em s˜ao apresentadas propriedades das parcerias entre os participantes, como n´umero de parceiros e suas dura¸c˜oes. Al´em disso, o estudo apresentado compreende diferentes canais do Sop- Cast, destacando diferen¸cas nos padr˜oes de comportamento dependendo do conte´udo. As caracteriza¸c˜oes apresentadas definem um modelo dos participantes, que pode ser usado como base para cria¸c˜ao de novos protocolos e gera¸c˜ao de cargas sint´eticas realistas para transmiss˜ao ao vivo em P2P.
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| 2. |
- Santos, Catarina L, et al.
(författare)
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Modulation of Frankia alni ACN14a oxidative stress response: activity, expression and phylogeny of catalases
- 2007
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Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 130, s. 454-463
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Tidskriftsartikel (refereegranskat)abstract
- The finding that an oxidative burst was a general phenomenon in the response of hosts challenged by various symbiotic or pathogenic microbes has stimulated increasing interest in investigating the enzymology of antioxidant protection in bacteria. The question of whether the antioxidant mechanisms have been a decisive evolutionary driving force for the nitrogen-fixing microsymbiont Frankia spp. is still open. In this study, Frankia alni strain ACN14a, which is a mid-range infective strain, was used as a model to explore the basal oxidative stress response in terms of enzymatic activity, relative expression and phylogeny. Non-denaturing polyacrylamide gels stained for catalatic activity revealed the presence of two monofunctional catalases KatA and KatB (EC number 1.11.1.6), which activity was shown to increase when the cells were challenged with the oxidants H2O2 and methyl viologen. Real-time RT-PCR targeting the two genes showed a consistent increase in the number of transcripts when the RNA was extracted from oxidative stress-induced cells. Comparison between the expression and the activity data suggests that posttranscriptional mechanisms might be involved in the regulation of catalases in F. alni. Furthermore, upstream of katA, a fur gene coding for a ferric uptake regulator was found, forming a gene pair that functionally resembles the conserved actinobacterial synton fur–katG, which contains a gene coding for a catalase–peroxidase. Phylogenetic analysis of the F. alni fur–katA synton suggests that this genomic organization was the result of genome reshuffling events.
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