Entity

Time filter

Source Type


Pires J.J.O.,University of Lisbon | Cancela L.G.C.,Higher Institute of Labour and Business
Journal of Lightwave Technology | Year: 2010

In-band crosstalk, due to multiple interferers, has been identified as one of the most severe impairments in optical transparent networks, especially in the ones with a large number of nodes and a high wavelength density. Due to its robustness to in-band crosstalk differential phase-shift keying (DPSK) emerges as an attractive modulation scheme to be used in such environments. This paper proposes a rigorous formulation to estimate the performance of direct-detection DPSK receivers using an eigenfunction expansion technique in the time domain. The method takes into account both the in-band crosstalk, due to an arbitrary number of interfering terms, and the amplified spontaneous emission noise and is able to deal with any combination of optical and electrical filter shapes. Using this method the accuracy of an approximation based on the wideband optical filtering assumption was evaluated and shown that the approximation, although not providing reliable results for the error probabilities, can be used with confidence to compute power penalties due to in-band crosstalk. Furthermore, the crosstalk tolerance of DPSK over on-off keying was quantified and shown that this tolerance is reduced when the number of interferers increases. © 2006 IEEE. Source


Pires J.J.O.,University of Lisbon | Cancela L.G.C.,Higher Institute of Labour and Business
Journal of Lightwave Technology | Year: 2010

This paper provides new theoretical insights into the properties of direct detection differential phase-shift keying (DPSK) signals impaired by coherent and incoherent crosstalk. Coherent crosstalk is due to multiple replicas originated while a data signal is routed through an optical network, whereas the source of incoherent crosstalk resides on the interference from other DPSK signals. A special emphasize has been put on modeling the multipath coherent crosstalk, with analytical expressions being derived and presented for both the moment generating function of the decision variable and the average error probability. A rigorous analysis, capable of dealing with arbitrary filtering, is also presented, which is used afterwards to assess the accuracy of the analytical formulas. A detailed comparison with incoherent crosstalk is also performed. Using also an exact treatment for this type of crosstalk it is shown that for low OSNR penalties the coherent crosstalk leads, in some circumstances, to slightly worse results than the incoherent one, but this situation is reversed when the total crosstalk level and the number of interferers increase. © 2010 IEEE. Source


Henriques J.M.,Higher Institute of Labour and Business
Revista Portuguesa de Saude Publica | Year: 2013

Healthy communities seek to improve the health of their citizens as a central aim of development policies and develop possibilities for health related 'economic integration'. They depend strongly on Municipal initiative in animating cross-sectoral policy integration and empowering civil society. Contemporary conditions require 'social innovation' depending on central paradigm shifts in science, in moving beyond 'deprivation-oriented' anti-poverty action, in linking health to territorial development and in developing adequate planning approaches. This paper discusses the above mentioned paradigm shifts, illustrates possibilities of action and suggests the possibility of 'learning from practice' based on the experience of the WHO Healthy Cities Movement. © 2012 Escola Nacional de Saúde Pública. Source


Matias N.-G.,Higher Institute of Labour and Business
Society and Natural Resources | Year: 2012

By conceptualizing a Portuguese reservoir and its surroundings as a social representation, this article empirically describes catchment residents' representations using a word association task as a consultation tool. The three stimulus terms were: "Reservoir and its surroundings," "Lake," and "Catchment." Words associated with each stimulus term were analyzed by a correspondence analysis to identify underlying structures according to word co-occurrence and their associations with sociodemographic characteristics and type of reservoir and its surroundings uses. The three analyses were subsequently compared to integrate and summarize the results. Overall, respondents conceived the study area as a productive water body, a natural area for recreation or leisure, and a social setting for free time with family and friends evocative of emotions/feelings that may have important restorative effects. The article concludes by discussing how the study approach and findings may provide an opportunity to capture the views of lay people and assist subsequent water management. © 2012 Copyright Taylor and Francis Group, LLC. Source


Allegra M.,Higher Institute of Labour and Business
Environment and Planning A | Year: 2013

Israel's settlement policy in the West Bank represents a crucial issue in the Israeli-Palestinian conflict. Through the examination of a single case study-the planning history of the Jewish settlement of Ma'ale Adummim, located in the eastern periphery of the city-the paper addresses the complex nexus between planning and state-building practices; building on Henri Lefebvre's theory of space, he offers an account of the role of Israel's settlement policy in the transformation of the material, symbolic, and political landscape of the metropolitan area of Jerusalem. My main argument is that the observation of the development of large suburban communities in the metropolitan area-a blind spot both in media and in academic discourse-is crucial for our understanding of the settlement policy as a whole, and its impact on Israeli-Palestinian relations. © 2013 Pion and its Licensors. Source

Discover hidden collaborations