Higher Institute of Labour and Business

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Time filter

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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.


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.


Silveirinha M.G.,University of Coimbra | Medeiros C.R.,University of Lisbon | Fernandes C.A.,University of Lisbon | Costa J.R.,University of Lisbon | Costa J.R.,Higher Institute of Labour and Business
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

Here, we report the experimental realization of a flat near-field lens formed by an array of densely packed crossed metallic wires. It is shown that due to the unusually strong electric response of the inclusions, the metamaterial slab may enhance the deep subwavelength spatial spectrum of a given source. It is experimentally demonstrated that when the superlens is placed in between the source and the image planes, keeping the propagation distance in the air regions unchanged, the resolution is boosted by a factor of 2 over a broad bandwidth that may exceed 25% the frequency of operation. © 2010 The American Physical Society.


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.


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.


De Jesus E.,Higher Institute of Labour and Business
ACM International Conference Proceeding Series | Year: 2011

This research aims to prove that an environment that establishes a direct connection between flowcharts and the equivalent structured programming language improves the results of the students in the first year of computer programming. The first approach is to do research on investigations about the teaching of the first year of computer programming. The next step is to build and test a prototype that allows the student to draw a flowchart and get the corresponding structured programming language and/or vice-versa, i.e., to write the program and get the corresponding chart. The research revealed that the first year of programming is crucial on building the basis for the following years and that visual tools are relevant in attaining better results. In the face of that, the pursuit for a dedicated application seems to be of value. © 2011 ACM.


Pedrosa I.,Polytechnic Institute of Coimbra | Costa C.J.,Higher Institute of Labour and Business
ACM International Conference Proceeding Series | Year: 2012

For many years, studies on Models for Individual Information Technology Acceptance were carried out and many approaches were released. All these models were meant to advance and define the determinant contributions on the user agreement on Information System and how this value can be a determinant factor to Information System adoption and success. The acceptance of Computer Assisted Audit Tools and Techniques is referred as difficult among internal auditors. This problem can arises when available tools and procedures involve relevant and complex background in several topics as Mathematics, Statistic and Advanced Concepts and Techniques on Information Systems. ANOVA or Data Mining algorithms and Artificial Intelligence on auditing procedures are examples of these evidences. This study intends to fully understand the way financial auditors use Information Technologies in their Auditing Tasks. To accomplish this main objective we did in-depth interviews focused upon financial auditors group. Is our intention to analyze and classify their contributions in order to provide further insights to the present research. Copyright 2012 ACM.


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.


Uzelgun M.A.,Higher Institute of Labour and Business | Castro P.,Higher Institute of Labour and Business
Environmental Communication | Year: 2014

This study aims to explore how the Turkish press represents the discourse of climate change scientists. This is achieved by analyzing climate change-related articles that quote scientists, directly and indirectly, in two Turkish mainstream newspapers (N = 132, 7 years). The Turkish case illustrates how scientific rhetoric is used for presenting climate change as a matter of concern in an industrializing country. The analysis suggests that climate science is portrayed as an un-discussed authority. News articles rely on data about the disturbance of species and the state of the natural environment to provide proof of global warming, by which they produce an implicit moral imperative. The articles also portray the worst threats and challenges -those pertaining to human society -as residing mostly in the future. We conclude by discussing the implications of the use of a projected future to convey a discourse emphasizing the alarming risks associated with climate change. © 2014 © 2014 Taylor & Francis.


Batista M.T.,Higher Institute of Labour and Business | Lima M.L.,Higher Institute of Labour and Business
Psicologia: Reflexao e Critica | Year: 2013

In this study we addressed the eating behavior of ambivalent people in different social contexts. Despite the evidence that food quality may play an important role, the literature just considers who the ones we share meals with are. Participants ate apple slices or potato chips, in one of the three experimental conditions: alone, in co-action with friends, or in co-action with strangers. The results confirm the hypothesis by showing that the more ambivalent participants are, the more sensitive to the context effects they become. Eating with friends only increased the consumption of unhealthy food (potato chips), and eating with strangers just increased healthy food consumption (apple). The outcomes are articulated with the theory of social facilitation.

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