Optical Power Control to Efficiently Handle Flex-Grid Spectrum Gain over Existing Fixed-Grid Network Infrastructures

International audienceThe exponential traffic growth in optical networks has triggered the evolution from Fixed-Grid to Flex-Grid technology. This evolution allows better spectral efficiency and spectrum usage over current networks in order to facilitate dynamic and huge traffic demands. The integration of Flex-Grid technology increases the number of optical channels established over optical links, leading, however, to an increase in amplification power and possibly saturating optical amplifiers. In this work, we propose a power adaptation process that takes advantage of link optical signal to noise ratio (OSNR) margins to allow network operators to support this power increase while maintaining the use of legacy amplifiers. Results show that controlling channel optical power benefits from the Flex-Grid in terms of spectrum and capacity gain using in-place amplifier infrastructure

On the Legacy Amplifier Limitation in Flexgrid Optical Networks

International audienceFlexgrid technology is an interesting solution to improve network capacity. However, for a given spectral band, it gives rise to the increase of the number of channels, requiring more amplification power in respect with the conventional fixed grid technology. In this work, we demonstrate that re-engineering the link margins allows supporting this increase while keeping in use legacy amplifier

GNPy experimental validation on flex-grid, flex-rate WDM optical transport scenarios

We demonstrate accurate GSNR predictions for a flex-grid and flex-rate experimental transmission using an enhanced implementation of the open-source GNPy library for a 1600 km OLS, involving QPSK, 8-QAM and 16-QAM modulation formats

Link Design and Legacy Amplifier Limitation in Flex-grid Optical Networks

International audienceFlex-grid technology is an effective mean to improve the spectral efficiency of optical communications. For a given amplifier spectral bandwidth, it gives rise to the increase of the number of optical channels as it reduces the channel spacing. Therefore, in order to reap full benefits from flex-grid saved spectrum, further amplification power is required with respect to conventional fixed grid. This is a strong limitation if the legacy amplifiers cannot meet this new requirement due to their optical power limits. In this work, we demonstrate that exploiting the link margins allows supporting this increase while maintaining in use legacy amplifiers

Lentiviral Vpx Accessory Factor Targets VprBP/DCAF1 Substrate Adaptor for Cullin 4 E3 Ubiquitin Ligase to Enable Macrophage Infection

Vpx is a small virion-associated adaptor protein encoded by viruses of the HIV-2/SIVsm lineage of primate lentiviruses that enables these viruses to transduce monocyte-derived cells. This probably reflects the ability of Vpx to overcome an as yet uncharacterized block to an early event in the virus life cycle in these cells, but the underlying mechanism has remained elusive. Using biochemical and proteomic approaches, we have found that Vpx protein of the pathogenic SIVmac 239 strain associates with a ternary protein complex comprising DDB1 and VprBP subunits of Cullin 4–based E3 ubiquitin ligase, and DDA1, which has been implicated in the regulation of E3 catalytic activity, and that Vpx participates in the Cullin 4 E3 complex comprising VprBP. We further demonstrate that the ability of SIVmac as well as HIV-2 Vpx to interact with VprBP and its associated Cullin 4 complex is required for efficient reverse transcription of SIVmac RNA genome in primary macrophages. Strikingly, macrophages in which VprBP levels are depleted by RNA interference resist SIVmac infection. Thus, our observations reveal that Vpx interacts with both catalytic and regulatory components of the ubiquitin proteasome system and demonstrate that these interactions are critical for Vpx ability to enable efficient SIVmac replication in primary macrophages. Furthermore, they identify VprBP/DCAF1 substrate receptor for Cullin 4 E3 ubiquitin ligase and its associated protein complex as immediate downstream effector of Vpx for this function. Together, our findings suggest a model in which Vpx usurps VprBP-associated Cullin 4 ubiquitin ligase to enable efficient reverse transcription and thereby overcome a block to lentivirus replication in monocyte-derived cells, and thus provide novel insights into the underlying molecular mechanism

Dual inhibition of HIV-1 replication by integrase-LEDGF allosteric inhibitors is predominant at the post-integration stage

BACKGROUND: LEDGF/p75 (LEDGF) is the main cellular cofactor of HIV-1 integrase (IN). It acts as a tethering factor for IN, and targets the integration of HIV in actively transcribed gene regions of chromatin. A recently developed class of IN allosteric inhibitors can inhibit the LEDGF-IN interaction. RESULTS: We describe a new series of IN-LEDGF allosteric inhibitors, the most active of which is Mut101. We determined the crystal structure of Mut101 in complex with IN and showed that the compound binds to the LEDGF-binding pocket, promoting conformational changes of IN which explain at the atomic level the allosteric effect of the IN/LEDGF interaction inhibitor on IN functions. In vitro, Mut101 inhibited both IN-LEDGF interaction and IN strand transfer activity while enhancing IN-IN interaction. Time of addition experiments indicated that Mut101 behaved as an integration inhibitor. Mut101 was fully active on HIV-1 mutants resistant to INSTIs and other classes of anti-HIV drugs, indicative that this compound has a new mode of action. However, we found that Mut101 also displayed a more potent antiretroviral activity at a post-integration step. Infectivity of viral particles produced in presence of Mut101 was severely decreased. This latter effect also required the binding of the compound to the LEDGF-binding pocket. CONCLUSION: Mut101 has dual anti-HIV-1 activity, at integration and post-integration steps of the viral replication cycle, by binding to a unique target on IN (the LEDGF-binding pocket). The post-integration block of HIV-1 replication in virus-producer cells is the mechanism by which Mut101 is most active as an antiretroviral. To explain this difference between Mut101 antiretroviral activity at integration and post-integration stages, we propose the following model: LEDGF is a nuclear, chromatin-bound protein that is absent in the cytoplasm. Therefore, LEDGF can outcompete compound binding to IN in the nucleus of target cells lowering its antiretroviral activity at integration, but not in the cytoplasm where post-integration production of infectious viral particles takes place

Epidémiologie des infections nosocomiales à SARM au CHU de Brest du 1er janvier 2004 au 31 décembre 2007 (impact des consommations de produits hydro-alcooliques et d'antibiotiques)

BREST-BU Médecine-Odontologie (290192102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Optical multi-band OFDM switching technology

International audienceWith the continuing growth in the amount of traffic, improving the flexibility and the transparency of optical networks is a very important problem facing operators today. In this paper, we present a networking technique based on optical multi-band Orthogonal Frequency Division Multiplexing. The optical multi-band OFDM approach enables optical switching at fine granularity in a highly spectrum-efficient manner. We study the performance of this approach in term of blocking compared to mono-band opaque and mono-band transparent OFDM technologies in an optical core network. We show that the flexibility offered by optical multi-band OFDM is efficient in term of blocking and that the sub-band granularity has an important impact on the blocking ratio

Proactive restoration of optical links based on the classification of events

International audienceWith the recent explosion of Internet traffic, bandwidth in optical core networks has greatly increased. Because of the huge volume of transported data and services, survivability in these networks is a big issue. Technical solution for securing this traffic takes advantage of reactive methods such as protection and restoration for rerouting the traffic in a case of a failure. Among the different reasons for failures, an important percentage is actually due to optical cables damage or cuts. In this paper, we propose a new method of proactive protection/restoration where the schemes are triggered before the optical fiber is cut. The method is based on the classification of the events occurring on the optical fiber. Events are monitored thanks to real time measurement of the optical fiber parameters. Classification is based on a suitable representation of the monitored parameters and a training set made of risky events allowing early detection of its premises. The advantage of the method is discussed with respect to its ability to reduce loss of data in case of a fiber cut and thus to improve network availability. Markov state model for proactive and reactive restoration of optical links has been developed for the availability analysis