Spanning trees with generalized degree constraints arising in the design of wireless networks

In this paper we describe a minimum spanning tree problem with generalized degree constraints which arises in the design of wireless networks. The signal strength on the receiver side of a wireless link decreases with the distance between transmitter and receiver. In order to work properly, the interference on the receiving part of the link must be under a given threshold. In order to guarantee this constraint, for each node we impose a degree constraint that depends on the ”length” of the links adjacent to the corresponding node, more precisely, nodes adjacent to long links must have a smaller degree and vice-versa. The problem is complicated by considering different signal strengths for each link. Increasing the strength in a link increases the cost of the link. However, it also reduces the maximum allowed degree on its end nodes. We create two models using adequate sets of variables, one may be considered an extended version of the other, and relate, from a theoretical perspective, the corresponding linear programming relaxations.FCT - POCTI-ISFL-1-152FCT - PTDC/EIA/64772/200

Conhecimentos dos alunos em Educação Física: Um estudo quasi-experimental com intervenção

Orientação: Francisco Alberto Arruda Carreiro da CostaO decréscimo de Atividade Física (AF) e os poucos conhecimentos adquiridos em Educação Física (EF) apresentados pela população escolar devem ser encarados como uma atual e alarmante preocupação para o futuro. O objetivo do estudo foi analisar os conhecimentos dos alunos do secundário relativamente à Educação Física relacionada com a saúde e avaliar o efeito de uma sessão de ensino teórico sobre o seu nível de conhecimento, designadamente as recomendações para a prática de AF. Participaram no estudo 72 alunos (Masculino=30, Feminino=42) de uma escola secundária. Os alunos foram divididos em dois grupos: o G1, para efeitos de estudo, foi definido como o Grupo de Controlo (GC) e o G2 como Grupo de Intervenção (GI). Num primeiro momento, foi aplicado aos dois grupos um questionário de avaliação de conhecimentos. Não se verificaram diferenças estatisticamente significativas entre os dois grupos. O GI foi submetido a uma intervenção teórica onde foram abordados conteúdos relacionando a aptidão física e a saúde e identificados os fatores associados a um estilo de vida saudável. Uma semana após a intervenção foi aplicado o questionário de avaliação de conhecimentos a ambos os grupos. Três semanas após a intervenção foi aplicado novamente o questionário apenas ao GI com o intuito de avaliar a retenção dos conhecimentos adquiridos. Os alunos do GI registaram uma evolução positiva nos seus conhecimentos registando-se uma maior percentagem de respostas corretas nas recomendações de AF quanto à intensidade, duração e tempo, benefícios da AF e perigos associados à inatividade física. Os alunos do GC mantiveram ao longo do estudo os mesmos conhecimentos. Os resultados deste estudo enfatizam a necessidade dos Professores de Educação Física utilizarem nas aulas estratégias que promovam, junto dos alunos, os conhecimentos que lhes permitam adotar, de forma consciente, um estilo de vida ativo e saudável ao longo da vida.The decrease in Physical Activity (AF) and the little knowledge acquired in Physical Education (PE) presented by the school population should be viewed as a current and alarming concern for the future. The objective of the study was to analyze the knowledge of the secondary students regarding Physical Education related to health and to evaluate the effect of a theoretical teaching session on their level of knowledge, namely the recommendations for the practice of PA. The study involved 72 students (Male = 30, Female = 42) from a secondary school. The students were divided in two groups: G1, for study purposes, was defined as the Control Group (CG) and G2 as the Intervention Group (GI). At first, a knowledge assessment questionnaire was applied to both groups. There were no statistically significant differences between the two groups. The GI was submitted to a theoretical intervention in which contents related to physical fitness and health were addressed and the factors associated with a healthy lifestyle were identified. One week after the intervention, the knowledge assessment questionnaire was applied to both groups. Three weeks after the intervention, the questionnaire was applied again only to the GI in order to evaluate the retention of the acquired knowledge. GI students had a positive evolution in their knowledge, with a higher percentage of correct answers in FA recommendations regarding intensity, duration and time, FA benefits, and hazards associated with physical inactivity. The students of the GC kept the same knowledge throughout the study. The results of this study emphasize the need for Physical Education Teachers to use, in their classes, strategies that promote knowledge among students and enable them to consciously adopt an active and healthy lifestyle throughout their lives

Cognitive, Evaluative, and Emotional Dynamics in the Relationship with Human Embryos among ART Beneficiaries

PTDC/SOC-SOC/29764/2017 UIDB/04647/2020 UIDP/04647/2020This article uses data gathered from a study conducted in Portugal to examine the (plural and composite) conceptions that doctors, embryologists, and beneficiaries of Assisted Reproductive Technology (ART) have of the in vitro human embryo. Taking the sociology of engagements, developed by Thévenot, as its theoretical lens, the article draws on a total of 69 interviews with ART patients to analyse the plurality of fluid meanings produced about this biological entity, whose status is neither static nor universal. ART beneficiaries are likely to produce plural conceptions of the lab-generated embryo within the framework of different regimes of engagement, understood as cognitive and evaluative formats. These various pragmatic regimes, in turn, entail distinct emotional investments. When speaking about their relationship with embryos, beneficiaries therefore express plural emotional experiences, which are articulated using terms such as affection, love, detachment, loss, frustration, hope, mourning, and anguish. Using the theoretical framework of the sociology of engagements, we propose an approach that enables us to produce a detailed record of the connections between the cognitive, evaluative, and emotional dimensions in beneficiaries’ relationship with—and decision-making processes about—the embryos, accounting for the plasticity of emotional states linked to the (re)configuration of attributed meanings.publishersversionpublishe

When moral values, habits, and/or affection prevail beyond efficiency

UIDB/04647/2020 UIDP/04647/2020This paper addresses the plural forms of reasoning used by clinical embryologists when deciding the fate of the human embryos they create and manipulate in the laboratory through assisted reproductive technologies (ART). Our analysis draws on empirical material from semi-directive interviews with 20 clinical embryologists working at public and private fertility units/clinics in Portugal. Within bureaucratic organizations based on a high level of functional specialization, embryologists display multiple perspectives about the criteria they use to evaluate and classify embryos’ quality, potential, and viability. Taxonomies, international guidelines, and statistical data are primarily used by embryologists to qualify the embryos, basing their action on instrumental rationality (efficient means and calculated ends recognized inductively). However, beyond technical-scientific facts and theories employed as intellectual tools for action, some of them also mobilize alternative ethical rationalities, specifically, value-rational action based on moral valuations and legitimate rules/ends. Affectual sub-rationality governed by emotions, affects, and feeling states (such as empathy with the beneficiaries), and traditional sub-rationality based on habits and routines (embryologists’ feelings gained by experience) intervene too. Therefore, Weber’s distinctive ideal types, namely his foundational four types of social action and rationality - but also combinations of them - are relevant for rethinking professional practices within ART, especially clinical embryology.publishersversionpublishe

Optimal prefilters for display enhancement

Creating images from a set of discrete samples is arguably the most common operation in computer graphics and image processing, lying, for example, at the heart of rendering and image downscaling techniques. Traditional tools for this task are based on classic sampling theory and are modeled under mathematical conditions which are, in most cases, unrealistic; for example, sinc reconstruction – required by Shannon theorem in order to recover a signal exactly – is impossible to achieve in practice because LCD displays perform a box-like interpolation of the samples. Moreover, when an image is made for a human to look at, it will necessarily undergo some modifications due to the human optical system and all the neural processes involved in vision. Finally, image processing practitioners noticed that sinc prefiltering – also required by Shannon theorem – often leads to visually unpleasant images. From these facts, we can deduce that we cannot guarantee, via classic sampling theory, that the signal we see in a display is the best representation of the original image we had in first place. In this work, we propose a novel family of image prefilters based on modern sampling theory, and on a simple model of how the human visual system perceives an image on a display. The use of modern sampling theory guarantees us that the perceived image, based on this model, is indeed the best representation possible, and at virtually no computational overhead. We analyze the spectral properties of these prefilters, showing that they offer the possibility of trading-off aliasing and ringing, while guaranteeing that images look sharper then those generated with both classic and state-of-the-art filters. Finally, we compare it against other solutions in a selection of applications which include Monte Carlo rendering and image downscaling, also giving directions on how to apply it in different contexts.Exibir imagens a partir de um conjunto discreto de amostras é certamente uma das operações mais comuns em computação gráfica e processamento de imagens. Ferramentas tradicionais para essa tarefa são baseadas no teorema de Shannon e são modeladas em condições matemáticas que são, na maior parte dos casos, irrealistas; por exemplo, reconstrução com sinc – necessária pelo teorema de Shannon para recuperar um sinal exatamente – é impossível na prática, já que displays LCD realizam uma reconstrução mais próxima de uma interpolação com kernel box. Além disso, profissionais em processamento de imagem perceberam que prefiltragem com sinc – também requerida pelo teorema de Shannon – em geral leva a imagens visualmente desagradáveis devido ao fenômeno de ringing: oscilações próximas a regiões de descontinuidade nas imagens. Desses fatos, deduzimos que não é possível garantir, via ferramentas tradicionais de amostragem e reconstrução, que a imagem que observamos em um display digital é a melhor representação para a imagem original. Neste trabalho, propomos uma família de prefiltros baseada em teoria de amostragem generalizada e em um modelo de como o sistema ótico do olho humano modifica uma imagem. Proposta por Unser and Aldroubi (1994), a teoria de amostragem generalizada é mais geral que o teorema proposto por Shannon, e mostra como é possível pré-filtrar e reconstruir sinais usando kernels diferentes do sinc. Modelamos o sistema ótico do olho como uma câmera com abertura finita e uma lente delgada, o que apesar de ser simples é suficiente para os nossos propósitos. Além de garantir aproximação ótima quando reconstruindo as amostras por um display e filtrando a imagem com o modelo do sistema ótico humano, a teoria de amostragem generalizada garante que essas operações são extremamente eficientes, todas lineares no número de pixels de entrada. Também, analisamos as propriedades espectrais desses filtros e de técnicas semelhantes na literatura, mostrando que é possível obter um bom tradeoff entre aliasing e ringing (principais artefatos quando lidamos com amostragem e reconstrução de imagens), enquanto garantimos que as imagens finais são mais nítidas que aquelas geradas por técnicas existentes na literatura. Finalmente, mostramos algumas aplicações da nossa técnica em melhoria de imagens, adaptação à distâncias de visualização diferentes, redução de imagens e renderização de imagens sintéticas por método de Monte Carlo

Climate responsibility premium : an event study on the US climate policy shock

Donald Trump’s election, Scott Pruitt’s nomination and the withdrawal of the United States of America from the Paris Agreement created expectations of a weaker environmental regulation in the country. This thesis studies the stock market reactions to these events on the Russell 3000 constituents. Investors rewarded carbon-intensive industries on the short run, as naïve intuition would suggest. However, and least expected, environmentally responsible firms also benefitted from these shocks. Such results are explained by the general increase in climate awareness, sparked by these events. Over the long run, the climate responsibility premium grew until the end of the year 2017, stagnating through the whole year of 2018. Changes in Donald Trump’s political influence consistently brought two different shocks to the climate responsibility premium. One from the perceived environmental deregulation, and the other from the rise in general climate awareness. The awareness shock prevailed until the end of 2017, benefitting climate responsible firms. The deregulation shock started overriding in 2018, as an increase in the President’s popularity began negatively affecting the premiumA eleição de Donald Trump, a nomeação de Scott Pruitt e a saída dos EUA do Acordo de Paris criaram expectativas de uma regulação ambiental mais ténue. Esta tese estuda as reações no mercado de ações durante estes eventos, nas empresas do índice Russell 3000. Os investidores recompensaram indústrias intensivas na emissão de CO2, como seria expectável. Contudo, e menos esperado, empresas responsáveis a nível ambiental foram também beneficiadas por estes choques. Tal resultado é explicado pelo aumento geral da consciência climática, espoletado por estes eventos. No longo prazo, o prémio de responsabilidade ambiental cresceu até ao final do ano 2017, estagnando durante todo o ano de 2018. Alterações na influência política de Donald Trump trouxeram consistentemente dois choques diferentes no prémio de responsabilidade climática. Um vindo da percecionada desregulação ambiental, e outro vindo do crescimento geral da consciência ambiental. O choque na consciência prevaleceu até o final do ano 2017, beneficiando empresas ambientalmente responsáveis. O choque da desregulação subrepôs-se durante o ano 2018, com os crescimentos de popularidade do Presidente a afetar negativamente o prémio de responsabilidade climátic

Resistência das variedades tradicionais de oliveira, Cobrançosa e Negrinha, em relação ao fungo Verticillium dahliae (Kleb)

As doenças vasculares associadas com o fungo do solo Verticillium dahliae Kleb provocam elevados prejuízos na oliveira em toda a região mediterrânica Na olivicultura 3. Resultados e Discussão Apresentam-se, para as diferentes variedades de oliveira, os resultados obtidos para os sintomas evidenciados nas folhas quando as plantas com um ano de enraizamento cresceram nas modalidades “não inoculado” (Branco) ou inoculadas com o isolado referência CECT2695 ou com o isolado Lx 211. Mirandela, 15 a 17 novembro 2012 mediterrânica. tradicional de Trás-os-Montes a doença tem prevalência e incidência não completamente conhecida mas com aumento da frequência no aparecimento de situações localizadas com alguma gravidade. A doença tem revelado maior importância nas novas plantações onde se utilizaram variedades não tradicionais. O fungo Verticillium dahliae Kleb (Fig 1) penetra pelas raízes e desenvolve-se nos tecidos vasculares afetando o transporte da água. As folhas ficam murchas, enroladas e pendentes (Fig. 2) levando à morte dos ramos ou mesmo de toda a árvore. As medidas de luta disponíveis, químicas e culturais, não são eficazes constituindo as variedades resistentes uma solução com muitas vantagens ecológicas e económica

Assessing Phytophthora Zoospore Activity to Enhance Disease Management and Promote Ecological Surveillance of Chestnut Ink Disease

Phytophthora cinnamomi and P. cambivora are soil borne oomycetes that cause Chestnut Ink Disease, a lethal and widespread disease of the European chestnut (Castanea sativa Mill.). Soil moisture is a key factor for the onset of Phytophthora root rot epidemics. Zoospores are the main infective propagules that reach the roots by swimming in liquid environments, become encysted and after that infect the host. Considering this biological uniqueness, we studied zoospore release and environmental conditions that promote zoospore production and host infection. Growing nursery media, previously infested with P. cinnamomi, were tested with different host plants (Castanea sativa, Camellia japonica, Ilex aquifolium) and different time-spans of flooding. Data analysis, made by nonparametric Kruskal- Wallis test and followed by multiple comparisons of mean ranks, found that infection of P. cinnamomi is significantly higher (p<0.001) on C. sativa. No significant differences were detected by a nonparametric two-way ANOVA analysis on studied environmental conditions. In natural soils, collected around the canopy of diseased chestnut trees, Phytophthora has a similar pattern of zoospore activity as on growing potting mix used as positive control. Variability between samples from the same tree was associated with physiographic and soil site conditions. This successful, simple and rapid methodology enables Phytophthora ecological surveillance and prompt implementation of sanitary management practices

The bank capital requirements in the SSM: a supervisory approach

The financial and supervisory data collection and analysis of the 128 significant institutions of the SSM shows that in 2017, on average, European banks were operating with a considerable excess regulatory total capital ratio. Although this might empirically challenge part of the literature – according to which banks would tend to operate with as much leverage as they are allowed to – a more granular analysis shows that despite the level playing field envisaged by the Banking Union, there are still statistically significant national differences among Pillar 2 capital add-ons, which were expected to address strictly idiosyncratic risks of institutions