490 resultados para ASYMMETRIES


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The ion Drift Kinetic Equation (DKE) which describes the ion coUisional transport is solved for the TJ-II device plasmas. This non-linear equation is computed by peribrming a mean field iterative calculation. In each step of the calculation, a Fokker-Planck equation is solved by means of the Langevin approach: one million particles are followed in a realistic TJ-II magnetic configuration, taking into account collisions and electric field. This allows to avoid the assumptions made in the usual neoclassical approach, namely considering radially narrow particle trajectories, diffusive transport, energy conservation and infinite parallel transport. As a consequence, global features of transport, not present in the customary neoclassical models, appear: non-diffusive transport and asymmetries on the magnetic surfaces.

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Tese de doutoramento, Estudos de Literatura e de Cultura (Cultura e Comunicação), Universidade de Lisboa, Faculdade de Letras, 2016

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Countries in a monetary union can adjust to shocks either through internal or external mechanisms. We quantitatively assess for the European Union a number of relevant mechanisms suggested by Mundell’s optimal currency area theory, and compare them to the United States. For this purpose, we update a number of empirical analyses in the economic literature that identify (1) the size of asymmetries across countries and (2) the magnitude of insurance mechanisms relative to similar mechanisms and compare results for the European Monetary Union (EMU) with those obtained for the US. To study the level of synchronization between EMU countries we follow Alesina et al. (2002) and Barro and Tenreyro (2007). To measure the effect of an employment shock on employment levels, unemployment rates and participation rates we perform an analysis based on Blanchard and Katz (1992) and Decressin and Fatas (1995). We measure consumption smoothing through capital markets, fiscal transfers and savings, using the approach by Asdrubali et al. (1996) and Afonso and Furceri (2007). To analyze risk sharing through a common safety net for banks we perform a rudimentary simulation analysis. |

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The EU began railway reform in earnest around the turn of the century. Two ‘railway packages’ have meanwhile been adopted amounting to a series of directives and a third package has been proposed. A range of complementary initiatives has been undertaken or is underway. This BEEP Briefing inspects the main economic aspects of EU rail reform. After highlighting the dramatic loss of market share of rail since the 1960s, the case for reform is argued to rest on three arguments: the need for greater competitiveness of rail, promoting the (market driven) diversion of road haulage to rail as a step towards sustainable mobility in Europe, and an end to the disproportional claims on public budgets of Member States. The core of the paper deals respectively with market failures in rail and in the internal market for rail services; the complex economic issues underlying vertical separation (unbundling) and pricing options; and the methods, potential and problems of introducing competition in rail freight and in passenger services. Market failures in the rail sector are several (natural monopoly, economies of density, safety and asymmetries of information), exacerbated by no less than 7 technical and legal barriers precluding the practical operation of an internal rail market. The EU choice to opt for vertical unbundling (with benefits similar in nature as in other network industries e.g. preventing opaque cross-subsidisation and greater cost revelation) risks the emergence of considerable coordination costs. The adoption of marginal cost pricing is problematic on economic grounds (drawbacks include arbitrary cost allocation rules in the presence of large economies of scope and relatively large common costs; a non-optimal incentive system, holding back the growth of freight services; possibly anti-competitive effects of two-part tariffs). Without further detailed harmonisation, it may also lead to many different systems in Member States, causing even greater distortions. Insofar as freight could develop into a competitive market, a combination of Ramsey pricing (given the incentive for service providers to keep market share) and price ceilings based on stand-alone costs might be superior in terms of competition, market growth and regulatory oversight. The incipient cooperative approach for path coordination and allocation is welcome but likely to be seriously insufficient. The arguments to introduce competition, notably in freight, are valuable and many e.g. optimal cross-border services, quality differentiation as well as general quality improvement, larger scale for cost recovery and a decrease of rent seeking. Nevertheless, it is not correct to argue for the introduction of competition in rail tout court. It depends on the size of the market and on removing a host of barriers; it requires careful PSO definition and costing; also, coordination failures ought to be pre-empted. On the other hand, reform and competition cannot and should not be assessed in a static perspective. Conduct and cost structures will change with reform. Infrastructure and investment in technology are known to generate enormous potential for cost savings, especially when coupled with the EU interoperability programme. All this dynamism may well help to induce entry and further enlarge the (net) welfare gains from EU railway reform. The paper ends with a few pointers for the way forward in EU rail reform.

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This BEER addresses informational barriers to energy efficiency. It is a widely acknowledged result that an energy efficiency gap exists implying that the level of energy efficiency is at an inefficiently low level. Several barriers to energy efficiency create this gap and the presence of asymmetric information is likely to be one such barrier. In this article a theoretical framework is presented addressing the issues of moral hazard and adverse selection related to energy efficiency. Based on the theoretical framework, European policies on energy efficiency are evaluated. The article is divided into two main parts. The first part presents the theory on information asymmetries and its consequences on energy efficiency focusing on the problems of moral hazard and adverse selection. Having established a theoretical framework to understand the agency barriers to energy efficiency, the second part evaluates the policies of the European Union on energy efficiency. The BEER finds that problems of moral hazard and adverse selection indeed can help explain the seemingly low levels of energy. In both presented models the cost to the principal from implementing high energy efficiency outcome is increased with the informational asymmetries. The theory reveals two implications to policies on energy efficiency. First, the development of measures to enable contractual parties to base remuneration on energy performance must be enhanced, and second, the information on technologies and the education of consumers and installers on energy efficiency must be increased. This could be complemented with certification of installers and energy efficiency advisors to enable consumers to select good agents. Finally, it is found that the preferred EU policy instrument on energy efficiency, so far, seems to be the use of minimum requirements. Less used in EU legislation is the use of measuring and verification as well as the use of certifications. Therefore, it is concluded that the EU should consider an increased use of these instruments, and in particular focus on a further development of standards on measurability and verification as well as an increased focus on education of consumers as well as installers and advisors on energy efficiency.

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Portugal provides a large number of factors that boost the development of the national equestrian tourism. It represents an opportunity for the qualification and differentiation of the national tourism, to stimulate rural economies, to combat seasonality and asymmetries.This study want to understand the importance, for the equestrian tourist, of the critical success factors such as the Lusitano horse, the national equestrian culture, the landscape diversity, among others. Also, how they can contribute to the differentiation of the national equestrian tourism for international destinations that are already deployed in the market.For this study is crucial to know the perspective of those involved in the various equestrian tourism activities. In this sense, a group of companies were selected and exploratory interviews were conducted that contributed to important outputs in the construction of the questionnaire.The research was attended by 110 individuals, with different profiles, motivations and types of involvement. From the analysis, it is concluded that the critical success factors are significant in motivating equestrian tourists, namely the quality of equestrian infrastructures, the Lusitano horse, the hospitality, among others. It is also possible to analyze that the equestrian tourist demonstrates a strong commitment: they are knowledgeable, read a lot about riding and belong to equestrian clubs.Finally, the factor analysis highlight the agreement between participants and a significant number of statements made in the questionnaire related to motivation and involvement. It is possible to conclude that equestrian tourists look for relaxing moments and opportunities to expand their equestrian knowledge.

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Trotz der steigenden Bedeutung von familienexternen Nachfolgeregelungen wie MBO und MBI bestehen hinsichtlich dieser Nachfolgeoptionen noch große Forschungslücken. Obwohl die Informationsökonomie einen viel versprechenden Ansatz darstellt, um ein fundierteres Verständnis zu erlangen, ist sie in diesem Kontext noch zu wenig angewandt worden. Dies wäre jedoch vor allem in Bezug auf einen MBI sinnvoll, da dort die deutlichsten Informationsasymmetrien zwischen Übergeber und Nachfolger auftreten können. In diesem Beitrag bedienen wir uns daher der Informationsökonomie und analysieren die verschiedenen Informationsasymmetrien bei einem MBI im Detail. Außerdem zeigen wir verschiedene Möglichkeiten auf, wie die entsprechenden Asymmetrien überwunden werden können. Damit leisten wir einen wertvollen Beitrag zu Wissenschaft und Praxis.

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Perceptual accuracy is known to be influenced by stimuli location within the visual field. In particular, it seems to be enhanced in the lower visual hemifield (VH) for motion and space processing, and in the upper VH for object and face processing. The origins of such asymmetries are attributed to attentional biases across the visual field, and in the functional organization of the visual system. In this article, we tested content-dependent perceptual asymmetries in different regions of the visual field. Twenty-five healthy volunteers participated in this study. They performed three visual tests involving perception of shapes, orientation and motion, in the four quadrants of the visual field. The results of the visual tests showed that perceptual accuracy was better in the lower than in the upper visual field for motion perception, and better in the upper than in the lower visual field for shape perception. Orientation perception did not show any vertical bias. No difference was found when comparing right and left VHs. The functional organization of the visual system seems to indicate that the dorsal and the ventral visual streams, responsible for motion and shape perception, respectively, show a bias for the lower and upper VHs, respectively. Such a bias depends on the content of the visual information.

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Thesis (Ph.D.)--University of Washington, 2016-06

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Differences between island- and mainland-dwelling forms provide several classic ecological puzzles. Why, for instance, are island-dwelling passerine birds consistently larger than their mainland counterparts? We examine the 'Dominance hypothesis', based on intraspecific competition, which states that large size in island passerines evolves through selection for success in agonistic encounters. We use the Heron Island population of Capricorn silvereyes (Zosterops lateralis chlorocephalus), a large-bodied island-dwelling race of white-eye (Zosteropidae), to test three assumptions of this hypothesis; that (i) large size is positively associated with high fitness, (ii) large size is associated with dominance, and (iii) the relationship between size and dominance is particularly pronounced under extreme intraspecific competition. Our results supported the first two of these assumptions, but provided mixed evidence on the third. On balance, we suggest that the Dominance Hypothesis is a plausible mechanism for the evolution of large size of island passerines, but urge further empirical tests on the role of intraspecific competition on oceanic islands versus that on mainlands.

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O estudo aponta como a internet ampliou as possibilidades de comunicação dos cidadãos de uma forma que não era possível no período do controle e concentração dos meios broadcasting sobre a informação social, assim, oferecendo espaço para a livre circulação de informação e novas possibilidades de comunicação. Entretanto, ressalta que ainda há assimetrias tanto do ponto de vista do acesso quanto do uso da rede em todas as suas potencialidades. Verifica que o atual momento ainda é de disputas em relação à legislação que diz respeito aos direitos e deveres dos que utilizam a rede. O trabalho foi realizado por meio de pesquisa bibliográfica e documental, tendo com base autores que pesquisam sobre as áreas da Comunicação, Tecnologias Digitais, Direito à Informação Social Livre e Legislação de internet, como Cicília Peruzzo, Manuel Castells, Rousiley Maia, Sérgio Amadeu da Silveira, Tim Wu, Tim Berners-Lee, Walter Lima Junior, Wilson Gomes e Yochai Benkler. O resultado da pesquisa demonstra que no cenário brasileiro, as desigualdades socioeconômicas são fator de desigualdade tanto em relação ao acesso quanto aos usos da internet, sendo dificultador para quem desejar se apropriar com liberdade deste desenvolvimento tecnológico. Portanto, cabe ao setor público interferir com vistas à diminuição das assimetrias informativas para garantir o direito de comunicação dos brasileiros no espaço de comunicação digital conectada.

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A assimetria das arcadas dentárias constitui um assunto de grande importância estudado por profissionais de Ortodontia na elaboração de um diagnóstico correto, planejamento e execução de um tratamento ortodôntico bem sucedido. O objetivo deste estudo foi avaliar o grau de assimetria das arcadas dentárias em indivíduos com oclusão normal e má oclusão de Classe II, divisão 1 e 2, bem como o dimorfismo sexual existente. Foram avaliados 180 pares de modelos de estudo de indivíduos do sexo masculino e feminino, na faixa etária de 12 a 21 anos, divididos em 3 grupos de 60 pares de modelos, de acordo com a má oclusão. Os grupos foram classificados em: Grupo 1 - indivíduos com oclusão normal, Grupo 2 - indivíduos com má oclusão de Classe II divisão 1 (Cl II 1), e Grupo 3 - indivíduos com má oclusão de Classe II divisão 2 (Cl II 2). Os modelos foram medidos utilizando-se um aparelho inédito, idealizado e fabricado exclusivamente para a análise de assimetria das arcadas dentárias. Para a análise de assimetria foram realizadas 2 medições angulares desvio de linha média (DLM), posicionamento dos caninos (PC) e 3 lineares distância dos caninos à rafe palatina (DC), distância inter-caninos (DIC), posicionamento dos primeiros molares no sentido ântero-posterior (PM). Concluiu-se que a ocorrência de assimetria nas arcadas dentárias independe da má oclusão. O Grupo 1 apresentou um menor grau de assimetria nas arcadas dentárias em relação aos grupos 2 e 3, os quais apresentaram um grau de assimetria semelhante. O grau de assimetria nas arcadas dentárias inferiores, nos 3 grupos, foi maior do que nas arcadas dentárias superiores. A direção do desvio da linha média apresentou uma correlação inversamente proporcional do lado em que o molar se apresentava mesializado, nas arcadas superior e inferior dos três grupos, com exceção da arcada superior no Grupo 2 (Classe II divisão 1). Houve dimorfismo sexual estatisticamente significante para algumas medidas, porém é importante considerar os baixos valores e a disposição, destas diferenças, entre as medidas realizadas, a qual revela ter se tratado de dados obtidos ao acaso.

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The paper describes epistemic marking in Ika (Arwako-Chibchan, Colombia) and proposes an analysis in terms of a typologically unusual pattern called conjunct/disjunct, which has been attested for a small number of Asian and South American languages. Canonically, conjunct occurs with first person subjects in statements and with second person in questions, as opposed to any other combination of subject and sentence-type, which is disjunct. The pattern found in Ika both conforms to expectations and, at the same time, contributes to a more nuanced analysis of the functional motivations of the conjunct/disjunct pattern. In Ika, conjunct marking encodes the speaker's direct access to an event that involves either (or both) of the speech participants. In addition, conjunct/disjunct marking interacts predictably with a second set of epistemic markers that encode asymmetries in the epistemic authority of the speaker and the addressee. The analysis builds on first-hand data but remains tentative, awaiting further investigation.

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This paper analyses the asymmetries in the response of petrol prices to oil price shocks. We show that previous work, based on the determination of asymmetric responses, can be improved upon by allowing for asymmetries in short term dynamics. The paper shows that a significant determinant of the response of petrol prices to oil price changes, is the extent to which petrol price can be seen to have departed from its long run equilibrium level.

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Recent studies of US industrial modernisation programmes argue that difficulties of establishing long-term relationships with users prevent them from facilitating development of innovation capabilities. The paper supports this argument through a survey of Japanese research institutes the US programmes were modelled on. In view of information asymmetries in their use, it tests the hypothesis that small and medium-sized firms start using the research institutes with ‘low information gap’ services and gradually move on to ‘high information gap’ services that often require more absorptive capacity. This is demonstrated both under one-to-one relationships and between groups of firms and a research institute.