Structural stability of bang-bang trajectories with a double switching time in the minimum time problem

In this paper we consider the problem of structural stability of strong local optimisers for the minimum time problem in the case when the nominal problem has a bang-bang strongly local optimal control which exhibits a double switch

Strong local optimality for generalized L1 optimal control problems

In this paper, we analyse control affine optimal control problems with a cost functional involving the absolute value of the control. The Pontryagin extremals associated with such systems are given by (possible) concatenations of bang arcs with singular arcs and with inactivated arcs, that is, arcs where the control is identically zero. Here we consider Pontryagin extremals given by a bang-inactive-bang concatenation. We establish sufficient optimality conditions for such extremals, in terms of some regularity conditions and of the coercivity of a suitable finite-dimensional second variation.Comment: Journal of Optimization Theory and Applications, Springer Verlag, In pres

Time varying ISI model for nonlinear interference noise

We show that the effect of nonlinear interference in WDM systems is equivalent to slowly varying inter-symbol-interference (ISI), and hence its cancellation can be carried out by means of adaptive linear filtering. We characterize the ISI coefficients and discuss the potential gain following from their cancellation.Comment: Submitted to the optical fiber communication conference (OFC), 201

Electronic equalization for advanced modulation formats in dispersion-limited systems

We investigate in this letter the use of electronic equalization on dispersion limited systems for different modulation formats. Besides analyzing equalization on standard NRZ intensity modulation as a reference, we focus on two advanced modulation formats, Duobinary and Differential Phase Shift Keying (DPSK) which are recently gaining large attention. We demonstrate that the introduction of an electronic equalizer strongly improves standard NRZ performance, whereas it has a limited effect on Duobinary and DPSK formats. Moreover, we give rules for the optimal choice of the equalizer transversal filter parameters, i.e., the number of taps and the delay between taps

Insights in the Regional Distribution and Physiological Role of the Cellular Prion Protein in the Central Nervous System of Mammalian Organisms

The cellular form of the prion protein (PrPC) is a sialoglycoprotein ubiquitously expressed in the central nervous system (CNS) of mammalian species along the neurodevelopment and in the adulthood. The PrPC localization in the brain has attracted interest because of its involvement in fatal neurodegenerative disorders, denoted as transmissible spongiform encephalopathies. In mammals, PrPC is expressed early in embryogenesis, and in the adulthood it reaches its highest levels in the neurons of the encephalon and spinal cord. The protein is also found at lower levels in glial cells of the CNS, as well as in almost all peripheral cell types. By combining in situ hybridization and immunohistochemical techniques, we show the earliest expression of the protein in mouse hippocampus, thalamus and hypothalamus. In particular, specific white matter fiber tracts in mouse CNS (the hippocampal fimbria, the stria terminalis, and the fasciculus retroflexus) show the highest expression of the protein. To extend our understanding of varying PrPC expression profiles in different mammals, we carried out a detailed expression analysis of PrPC distribution along the neurodevelopment of the metatherian South American short-tailed opossum (Monodelphis domestica). No naturally occurring prion diseases have been reported yet for this species. Compared with mice, in opossums we detected lower levels of PrPC in the white matter fiber bundles of the CNS. This result might offer new insights into a possible involvement of PrPC in the varying susceptibility to prion diseases for different mammals. The different distribution of PrPC in the hippocampal layers of mammals led us to hypothesize a different physiological relevance of PrPC in this region. To better understand this issue, we used PrP knock-out mice, in which PrPC is not expressed in the hippocampal strata. We observed that the absence of PrPC impairs the signaling pathway promoted by Reelin, a protein of the extracellular matrix expressed in the stratum lacunosum molecolare and hippocampus of the early postnatal mouse. Overall, our findings suggest a possible role for PrPC in the modulation of the events triggered by the Reelin-signaling pathway in the developmental mouse hippocampus

Optical phase-locked loop for coherent detection optical receiver

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