Space Division Multiplexing in Optical Fibres

Optical communications technology has made enormous and steady progress for several decades, providing the key resource in our increasingly information-driven society and economy. Much of this progress has been in finding innovative ways to increase the data carrying capacity of a single optical fibre. In this search, researchers have explored (and close to maximally exploited) every available degree of freedom, and even commercial systems now utilize multiplexing in time, wavelength, polarization, and phase to speed more information through the fibre infrastructure. Conspicuously, one potentially enormous source of improvement has however been left untapped in these systems: fibres can easily support hundreds of spatial modes, but today's commercial systems (single-mode or multi-mode) make no attempt to use these as parallel channels for independent signals.Comment: to appear in Nature Photonic

Application pratique et intérêt des recommandations de prise en charge des syncopes : évaluation de pratiques professionnelles

AIMS: To assess the practical implementation of international guidelines and their impact on syncope management in a 500-bed general hospital. PATIENTS AND METHODS: Three groups of 63 consecutive patients admitted for syncope to the emergency care unit (ECU) were studied: group 1, before the guidelines delivered to the practitioners, group 2 immediately after the diffusion of guidelines and group 3, one year later. The study evaluates the mean duration of stay (MDS) and the relevance of the diagnostic strategy. RESULTS: In group 1 compared to group 2, MDS were respectively 6.8±5.5 and 5.4±2.8 days (P=0.07) and the unexplained syncope number respectively 22% and 24% (P=0.8). The search of orthostatic hypotension became more systematic (13% versus 86% in group 1 and 2 respectively, P<0.001). The agreement (kappa coefficient) between initial and final diagnostic increased in 0.34 to 0.44. One year later MDS in group 3 was 7.1±4.7 days (P=0.8 versus group 1 and P=0.015 versus group 2) with only 6.3% systematic search for orthostatic hypotension (P<0.001). CONCLUSIONS: Guidelines optimize the syncope management in the ECU and the agreement between the emergency and discharge diagnostic without change of unexplained syncope and. MDS tend to be shorter when guidelines are actively implemented. Nevertheless, the positive impact of guidelines implementation is of limited duration