A institucionalização do desenvolvimento sustentável em Portugal: Estudo exploratório no contexto setorial do turismo

A institucionalização do desenvolvimento sustentável em Portugal surge num quadro político internacional, no qual as Nações Unidas e a União Europeia têm direcionado e comprometido cada vez mais a ação governativa dos países membros. Ancorando neste contexto, e numa perspetiva cronológica, o objetivo principal deste artigo é identificar a retórica que surge no contexto político-institucional no qual o setor turístico está comprometido no processo de desenvolvimento sustentável. Em termos metodológicos optou-se por fazer uma análise de conteúdo exploratória a documentos de cariz político, em duas fases complementares. Numa primeira, a abordagem focou-se nos documentos nacionais de estratégia política, editados pelo governo, que versam sobre o ambiente e o desenvolvimento sustentável. Nesta análise procurou-se identificar se os documentos fazem referências ao setor do turismo e, quando o fazem, em que moldes são apresentadas. Numa segunda fase procurou-se identificar como é que os documentos oficiais de política e estratégia turística nacionais aludem ao desafio do setor para promover um turismo mais sustentável. Uma das conclusões da análise é que o setor turístico surge referido nas políticas nacionais de desenvolvimento sustentável a par de outras atividades e setores que necessitam de apresentar medidas setoriais prioritárias devido aos impactos que geram

Optimização da distorção não-linear de intermodulação em amplificadores de sinais multi-portadora

Doutoramento em Engenharia ElectrónicaÉ objectivo principal desta Tese de Doutoramento o estudo e Optimização da Distorção Não-linear de Intermodulação em Amplificadores de Sinais Multi-Portadora. A Tese divide-se em duas grandes áreas de investigação. Primeiro o problema da simulação de circuitos não lineares sujeitos a sinais multiportadora é visado. Para esse efeito é proposta uma solução inovadora para a simulação do regime estacionário desse tipo de circuitos, validando-se ainda experimentalmente a sua utilidade. O segundo problema consiste na compreensão e optimização da distorção num circuito não linear fortemente excitado por um sinal multiportadora. Para se levar o estudo a bom termo, este é dividido em duas etapas. Em primeiro lugar estuda-se a resposta do circuito quando sujeito a um sinal fraco, seguindo-se a extrapolação desses resultados para sinal forte. Propõe-se, assim, um novo modelo comportamental, que permite projectar amplificadores de potência optimizados para uma pretendida curva de distorção versus nível de excitação de entrada. Utilizando o simulador desenvolvido e o modelo comportamental proposto, apresentam-se validações experimentais de um amplificador de potência projectado para se obter uma distorção de intermodulação mínima perto do ponto de 1dB de compressão da sua curva Pin-Pout.The main objective of this Doctoral Thesis is the study and Optimisation of Multi-tone Non-linear Power Amplifiers. The work can be divided into two research areas. First, the simulation of non-linear circuits excited by a multi-tone signal is addressed. For that, a novel non-linear simulator solution, specially suited for this type of circuit, is developed and validated using experimental results. The second research field is the optimisation of a non-linear power amplifier excited by a strong multi-tone signal. This study is carried on in two different steps. The first step is the study of that amplifier excited by a small signal, which is then followed by the explanation of large signal behaviour. So, a new behavioural model is presented, in order to design power amplifiers specially tailored to present a pre_determined intermodulation distortion curve versus excitation level. Finally, the proposed circuit simulator and the referred behavioural model, are validated by comparing experimental results with simulations, for a power amplifier designed to present a minimum intermodulation distortion near the 1dB compression point in its Pin-Pout plot

An evaluation of official Government Tourism Websites as a knowledge-based platform to improve the development of sustainable tourism

The development of sustainable tourism is a very extensive domain of work and characterized by many complex challenges that increase with the global market pursuit to become more competitive. A knowledge-based platform is essential for policy makers and managers in order to support responsible decision making at different levels. Tourism is an area of increasingly intensive production and consumption of information. The main purpose of this study is to analyze if Portuguese public organizations, operating in the tourism destination of the Alentejo, use official tourism websites to transfer knowledge with a view to sharing data and information about the overall scope of sustainable development issues. It was used the content analysis research technique to evaluate the set of characteristics of information content within official websites. The results indicate these organizations are not very committed to using official websites as a knowledgebased platform to share information

A ETIOLOGIA DA APENDICITE AGUDA. SERÁ A ALERGIA O ELO PERDIDO? UMA REVISÃO NARRATIVA

Acute appendicitis is the most common abdominal surgical emergency. Since the work of Fitz in the XIX century it has been assumed that luminal obstruction is the main pathological event. However, this theory has been recently challenged by some new insights that suggest that an allergic reaction can be one of the possible causes or co-factors. The current knowledge on the aetiology of acute appendicitis was reviewed in this article, with a special emphasis on allergic features.A apendicite aguda é a mais comum urgência cirúrgica abdominal. Desde o trabalho paradigmático de Fitz, no final do século XX, assumiu-se que a obstrução do lúmen apendicular é o principal evento patológico. Esta teoria foi questionada recentemente, pois alguns estudos sugerem que a alergia pode ser uma causa ou co-factor na etiologia da apendicite aguda. Os autores procedem a revisão da etiologia da apendicite aguda, com particular enfase na reação alérgica.   &nbsp

Swept Notch NPR for Linearity Assessment of Systems Presenting Long-Term Memory Effects

Mobile and Satellite applications are progressively moving towards broader bandwidths, so nonlinear long-term memory effects manifested by RF Transmitters must not be neglected. This trend evidences the need for more informative and robust broadband linearity metrics. This work proposes a swept notch noise power ratio to capture co-channel long-term memory effects, moving the scientific discussion toward the definition of useful metrics for broadband nonlinear memory assessment

A Novel Measurement Standard for Nonlinear In-Band Distortion Characterization

Abstract -This paper proposes a novel measurement standard for nonlinear in-band distortion characterization. Based on a previously established theoretical work, it first identifies the main limitations of noise power ratio figure of merit. Then, an appropriate alternative is proposed, along with its required measurement set-up

Linearity-aware design of Doherty power amplifiers

The linearity is a crucial requirement of power amplifiers. At design level, it is typically assessed by means of AM/AM, AM/PM and IMR, which are extracted from 1- and 2-tone characterization. These however are not fully representative of the actual behaviour under modulated signal excitation, for which purpose other system-level metrics such as the NPR have been successfully introduced. In this paper, different linearity estimations are used to compare two GaN-on-Si Doherty MMIC power amplifiers for Ka-band space applications. One of the two amplifiers shows an AM/PM reduction of more than 30% with respect to the other. However, it is observed that this does not always lead to a reduction in NPR. The reasons for this disagreement between metrics are analysed and discussed

Knowledge transfer for the development of sustainable tourism: focus on official Portuguese tourism websites

To achieve development of sustainable tourism, policy makers and managers need up-to-date, accurate and relevant knowledge. Therefore, a tourism knowledge platform is essential for all stakeholders. Additionally, the internet is part of the day-to-day life of people and organisations, with all its inherent advantages. In this context, the present article features how the internet has been used by Portuguese public organisations operating in the tourism destination of the Alentejo to disseminate information about sustainable tourism. The content analysis research technique was used to evaluate information content within offi cial tourism websites with a view to sharing data and information about the overall scope of sustainable development issues. The outcomes demonstrate that these websites are not used as platforms for knowledge transfer concerning sustainable tourism