96 resultados para 362.11
Resumo:
11 September heralded and provided a pretext for a more aggressive but increasingly contradictory American hegemony. Some of the consequences are contrary to the United States' own interests. Its new doctrine of 'preemptive strike' against other sovereign states encourages similarly belligerent behaviour by other governments, and yet more terrorism by nonstate actors, the very threats which were to be eradicated by a re-asserted US hegemony. This essay focuses on three partly overlapping themes: different strategies towards allies - multilateral and unilateral; different forms of power - civil and military; and different ideologies of globalisation - neoliberal and neo-conservative. It argues that while US policy may oscillate between such poles, it often combines the different elements. The overall strategy of the Bush administration is best characterised as unilateral multilateralism. The main issue for US hegemonists is the ways in which their hegemony might best be exercised, maintained and strengthened vis à vis allies and rivals. But for a safer, more democratic world, the choice does not lie between one faction of US hegemonists and another: we need other alternatives such as cosmopolitan democracy and a genuine internationalist movement which would give it some much-needed substance.
Resumo:
CDK11(p58), a 58kDa protein of the PITSLRE kinase family, plays an important role in cell cycle progression, and is closely related to cell apoptosis. To gain further insight into the function of CDK11(p58), we screened a human fetal liver cDNA library for its interacting proteins using the yeast two-hybrid system. Here we report that histone acetyltransferase (HAT) HBO1, a MYST family protein, interacts with CDK11(p58) in vitro and in vivo. CDK11(p58) and HBO1 colocalize in the cell nucleus. Recombinant CDK11(p58) enhances the HAT activity of HBO1 significantly in vitro. Meanwhile, overexpression of CDK11(p58) in mammalian cells leads to the enhanced HAT activity of HBO1 towards free histones. Thus, we conclude that CDK11(p58) is a new interacting protein and a novel regulator of HBO1. Both of the proteins may be involved in the regulation of eukaryotic transcription.
Resumo:
In the IEEE 802.11 MAC layer protocol, there are different trade-off points between the number of nodes competing for the medium and the network capacity provided to them. There is also a trade-off between the wireless channel condition during the transmission period and the energy consumption of the nodes. Current approaches at modeling energy consumption in 802.11 based networks do not consider the influence of the channel condition on all types of frames (control and data) in the WLAN. Nor do they consider the effect on the different MAC and PHY schemes that can occur in 802.11 networks. In this paper, we investigate energy consumption corresponding to the number of competing nodes in IEEE 802.11's MAC and PHY layers in error-prone wireless channel conditions, and present a new energy consumption model. Analysis of the power consumed by each type of MAC and PHY over different bit error rates shows that the parameters in these layers play a critical role in determining the overall energy consumption of the ad-hoc network. The goal of this research is not only to compare the energy consumption using exact formulae in saturated IEEE 802.11-based DCF networks under varying numbers of competing nodes, but also, as the results show, to demonstrate that channel errors have a significant impact on the energy consumption.
Resumo:
The reaction mechanism and the rate-determining step (RDS) of the isomerisation of n-alkanes (C-4-C-6) over partially reduced MoO3 catalysts were studied through the effects of the addition of an alkene isomerisation catalyst (i.e. CoAlPO- 11). When an acidic CoAlPO- 11 sample was mechanically mixed with the MoO3, a decrease of the induction period and an increase of the steady-state conversion of n-butane to isobutane were observed. These data support previous assumptions that a bifunctional mechanism occurred over the partially reduced MoO3 (a complex nanoscale mixture of oxide-based phases) during n-butane isomerisation and that the RDS was the skeletal isomerisation of the linear butene intermediates. The only promotional effect of CoAlPO-11 on the activity of partially reduced MoO3 for C-5-C-6 alkane hydroisomerisation was a reduction of the induction period, as the RDS at steady-state conditions appeared to be dehydrogenation of the alkane in this case. However, lower yields of branched isomers were observed in this case, the reason of which is yet unclear. (c) 2005 Elsevier B.V. All rights reserved.
Resumo:
Study which shows that 10-11 yr olds are capable of effective CPR after a single 2 hour training session using the ABC for Life programme. However they perfrom more effective CPR when using a ratio of 15:2 rather than 30:2 chest compressions : ventilations
Resumo:
Quality of Service (QoS) support in IEEE 802.11-based ad hoc networks relies on the networks’ ability to estimate the available bandwidth on a given link. However, no mechanism has been standardized to accurately evaluate this resource. This remains one of the main issues open to research in this field. This paper proposes an available bandwidth estimation approach which achieves more accurate estimation when compared to existing research. The proposed approach differentiates the channel busy caused by transmitting or receiving from that caused by carrier sensing, and thus improves the accuracy of estimating the overlap probability of two adjacent nodes’ idle time. Simulation results testify the improvement of this approach when compared with well known bandwidth estimation methods in the literature.
Resumo:
Nidoviruses (arteriviruses, coronaviruses, and roniviruses) are a phylogenetically compact but diverse group of positive-strand RNA viruses that includes important human and animal pathogens. Nidovirus RNA synthesis is mediated by a cytoplasmic membrane-associated replication/transcription complex that includes up to 16 viral nonstructural proteins (nsps), which carry common enzymatic activities, like the viral RNA polymerase, but also unusual and poorly understood RNA-processing functions. Of these, a conserved endoribonuclease (NendoU) is a major genetic marker that is unique to nidoviruses. NendoU activity was previously verified in vitro for the coronavirus nsp15, but not for any of its distantly related orthologs from other nidovirus lineages, like the arterivirus nsp11. Here, we show that the bacterially expressed nsp11 proteins of two arteriviruses, equine arteritis virus and porcine respiratory and reproductive syndrome virus, possess pyrimidine-specific endoribonuclease activity. RNA cleavage was independent of divalent cations in vitro and was greatly reduced by replacement of residues previously implicated in catalysis. Comparative characterization of the NendoU activity in arteriviruses and severe acute respiratory syndrome coronavirus revealed common and distinct features of their substrate requirements and reaction mechanism. Our data provide the first biochemical evidence of endoribonuclease activity associated with arterivirus nsp11 and support the conclusion that this remarkable RNA-processing enzyme, whose substrate in the infected cell remains to be identified, distinguishes nidoviruses from all other RNA viruses.