1000 resultados para Perspective.


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This paper analyses the performance of a genetic algorithm (GA) in the synthesis of digital circuits using two novel approaches. The first concept consists in improving the static fitness function by including a discontinuity evaluation. The measure of variability in the error of the Boolean table has similarities with the function continuity issue in classical calculus. The second concept extends the static fitness by introducing a fractional-order dynamical evaluation.

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This article presents a novel method for visualizing the control systems behavior. The proposed scheme uses the tools of fractional calculus and computes the signals propagating within the system structure as a time/frequency-space wave. Linear and nonlinear closed-loop control systems are analyzed, for both the time and frequency responses, under the action of a reference step input signal. Several nonlinearities, namely, Coulomb friction and backlash, are also tested. The numerical experiments demonstrate the feasibility of the proposed methodology as a visualization tool and motivate its extension for other systems and classes of nonlinearities.

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The present article is based on the report for the Doctoral Conference of the PhD programme in Technology Assessment, held at FCT-UNL Campus, Monte de Caparica, June 9th, 2011. The PhD thesis has the supervision of Prof. António Moniz (FCT-UNL and ITAS-KIT), and co-supervision of Prof. Manuel Seabra Pereira and Prof. Rosário Macário (both from IST-UTL).

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Normal human metabolism leads to the daily production of large amounts of volatile and non-volatile acids. The maintenance of the pH within physiological limits is a demanding task in which several mechanisms are involved. The most immediate answer comes from several physiological buffers that quickly neutralize pH deviations caused by the addition of strong acids or bases to the body. Bicarbonate/carbonic acid is the most important buffer pair of the extracellular milieu, but is chemically inefficient and depends on the continuous activity of the lung and kidney. Other physiological buffers have higher efficacy and are very important in the intracellular environment and renal tubules. The capacity of the various chemical buffers is kept by operating in an open system and by several controlling mechanisms. The lung is responsible for the elimination of the carbon dioxide (CO2) produced in the body. In metabolic disorders, respiratory adjustment of the elimination of CO2 prolongs the effect of the bicarbonate/carbonic acid buffer, but this process consumes bicarbonate. The kidney contributes to acid-base balance through several mechanisms: 1) controls the reabsorption of filtered bicarbonate; 2) regenerates bicarbonate consumed in buffer reactions; 3) eliminates non-volatile acids. Renal elimination of acid and bicarbonate regeneration is only possible due to the existence of several urinary buffers and to the ability of the kidneys to produce ammonia

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The occurrence of leprosy has decreased in the world but the perspective of its elimination has been questioned. A proposed control measure is the use of post-exposure chemoprophylaxis (PEP) among contacts, but there are still questions about its operational aspects. In this text we discuss the evidence available in literature, explain some concepts in epidemiology commonly used in the research on this topic, analyze the appropriateness of implementing PEP in the context of Brazil, and answer a set of key questions. We argue some points: (1) the number of contacts that need to receive PEP in order to prevent one additional case of disease is not easy to be generalized from the studies; (2) areas covered by the family health program are the priority settings where PEP could be implemented; (3) there is no need for a second dose; (4) risk for drug resistance seems to be very small; (5) the usefulness of a serological test to identify a higher risk group of individuals among contacts is questionable. Given that, we recommend that, if it is decided to start PEP in Brazil, it should start on a small scale and, as new evidence can be generated in terms of feasibility, sustainability and impact, it could move up a scale, or not, for a wider intervention.

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Dissertação para obtenção do grau de Mestre em Engenharia do Ambiente, perfil de Gestão e Sistemas Ambientais

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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Finance from the NOVA – School of Business and Economics

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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics

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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Finance from the NOVA – School of Business and Economics

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Dissertation presented to obtain the Ph.D degree in Biochemistry

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Tese apresentada como requisito parcial para obtenção do grau de Doutor em Gestão de Informação

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Dissertação para obtenção do Grau de Mestre em Genética Molecular e Biomedicina

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The design of work organisation systems with automated equipment is facing new challenges and the emergence of new concepts. The social aspects that are related with new concepts on the complex work environments (CWE) are becoming more relevant for that design. The work with autonomous systems implies options in the design of workplaces. Especially that happens in such complex environments. The concepts of “agents”, “co-working” or “human-centred technical systems” reveal new dimensions related to human-computer interaction (HCI). With an increase in the number and complexity of those human-technology interfaces, the capacities of human intervention can become limited, originating further problems. The case of robotics is used to exemplify the issues related with automation in working environments and the emergence of new HCI approaches that would include social implications. We conclude that studies on technology assessment of industrial robotics and autonomous agents on manufacturing environment should also focus on the human involvement strategies in organisations. A needed participatory strategy implies a new approach to workplaces design. This means that the research focus must be on the relation between technology and social dimensions not as separate entities, but integrated in the design of an interaction system.

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The virtuous cycle between development success and foreign policy in Cape Verde reflects a positive interaction between globalization and governance. Development success under globalization entails positive market perceptions regarding the orientation and predictability of policies as well as the accompanying institutional arrangements, thereby making foreign policy salient beyond the comparator group, or “aspirational”. Even if there is no universally applicable development model, an aspirational foreign policy can be built on positive rankings with respect to comparator groups. In Macedo and Pereira (2010), macrolevel policy and institutional combinations underpinning trade diversification and income convergence in West and Southern Africa are used to establish development success for Cape Verde and Mozambique respectively. Here, the narrative of long-term development helps identify the following drivers: moving towards a market economy; opening up to regional and global trade; increasing economic and political freedom; pursuing macroeconomic stability and financial reputation; ensuring policy continuity (especially in trade and industrial sectors) and focusing on human development (especially poverty reduction and education). Looking at GDP per capita and indicators of financial reputation and good governance of sub-regional peers is not sufficient to conclude that Cape Verde’s convergence will be sustained. Nevertheless, the positive interaction between trade and financial globalization, on the one hand, and democracy and good governance, on the other, have positive implications for the effectiveness of foreign policy across the region as well as in the Portuguese-speaking community.