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- Formação de preços e integração internacionalPublication . Santos, Vítor Manuel da SilvaUma primeira preocupação deste trabalho é procurar esclarecer os mecanismos decisionais no sector exportador e nos ramos que defrontam importações competitivas tendo em vista analisar a eficácia das políticas com incidências nestes sectores. O estudo está organizado em seis secções. Na primeira secção concentramos a nossa atenção nas limitações das equações temporais de preços que normalmente são utlizadas para discriminar entre bens comerciáveis e não comerciáveis. Como não nos interessa tanto classificar os diferentes ramos de actividade mas antes evidenciar os choques exógenos têm efeitos sectorialmente diferenciados, na secção 2 estabelecemos o enquadramento teórico que permite implementar uma análise cross-section. Nas secções 3 e 5 analisamos as implicações na modelização que poderão decorrer do facto das firmas domésticas não terem comportamentos marginalistas. A este respeito há que ponderar duas questões: - na secção 3 referimo-nos à possibilidade das firmas não tomarem como referência os custos marginais e fixarem um mark-up insensível às flutuações da procura e basicamente determinado pelos custos médios esperados; - na secção 5 estudamos o impacte que a existência de uma política de controle dos preços tem sobre a consistência de um modelo que pressupõe que as firmas não são confrontadas com restrições institucionais. Na secção 4 é proposta a especificação do modelo misto que vamos utilizar tomando como domínio de observação o período de 1977-82 a 21 ramos de actividade. Finalmente na secção 6 explicitamos os principais resultados empíricos alcançados.
- A reforma das finanças locais na óptica da nova gestão públicaPublication . Sá, Jorge A. Vasconcellos e; Santos, Ana BelaO processo de mudança em curso nas nossas autarquias deve conduzir à substituição de uma cultura administrativa tradicional, assente em procedimentos que visam assegurar predominantemente equilíbrios e controlos formais, por uma cultura de mercado (cit in Bouvier, Michel, 1993). A introdução da reforma iniciada em 1979 aumentou o grau de descentralização da Administração Pública, permitindo as autarquias, quer um maior volume de recursos financeiros, quer um maior poder discricionário na sua utilização. Porém, o actual sistema de finanças locais ainda apresenta limitações, a justificar a reforma actualmente em discussão. Este artigo apresenta sugestões para a reforma das finanças locais. Ao contrário das propostas que estão publicadas que incidem sobretudo nas fontes e no montante de financiamento da Administração Local, pensamos que a reforma deveria ser acompanhada por alterações nos modelos de gestão autárquica. Embora a existência de autonomia de as autarquias o poder de decidir sobre a gestão autárquica 3 a entidade de tutela deveria incentivar a adoção de processes conducentes à melhoria da performance, a semelhança do que sucede noutros países. As teorias das Escolhas Públicas (Public Choice) fornecem um substrato teórico para a orientação que tem conduzido as reformas recentes dos sistemas de administração local, cujas linhas programáticas têm um tronco comum que se costuma identificar com a denominada NPM - New Public Management. Pensamos que a abordagem da NPM oferece um valioso contributo para a discussão em torno da reforma das finanças locais, que não têm sido explorados pelos vários estudos publicados. Este enfoque acentua os objectivos de eficiência e eficácia na utilização dos recursos locais, de modo que à reivindicação dos autarcas de MAIS RECURSOS se deve acrescentar a exigência das populações de MAIS RESULTADOS, ou em inglês more value for money.
- Simulated likelihood estimation of non-linear diffusion processes through non-parametric procedure with an application to the portuguese interest ratePublication . Nicolau, JoãoIn this article we present a new model of the spot interest rate and a new method of estimation of nonlinear stochastic differential equations. We show how an integrated discrete time process in an econometric sense can be modelled by a continuous time ergodic process. We make an application to the Portuguese spot interest rate.
- A Comparison of Discrete and Continuous Neural Network Approaches to Solve the Class/Teacher Timetabling ProblemPublication . Carrasco, Marco Paulo; Pato, Margarida VazThis study explores the application of neural network-based heuristics to the class/teacher timetabling problem (CTTP). The paper begins by presenting the basic CTTP characteristics in terms of hard and soft constraints and proposing a formulation for the energy function required to map the problem within the artificial neural network model. There follow two distinct approaches to simulating neural network evolution. The first uses a Potts mean-field annealing simulation based on continuous Potts neurons, which has obtained favorable results in various combi¬natorial optimization problems. Afterwards, a discrete neural network simulation, based on discrete winner-take-all neurons, is proposed. The paper concludes with a comparison of the computational results taken from the application of both heuris¬tics to hard hypothetical and real CTTP instances. This experiment demonstrates that the discrete approach performs better, in terms of solution quality as well as execution time.
- Hedonic prices indexes for new passenger cars in Portugal (1997-2001)Publication . Reis, Hugo J.; Silva, J. M. C. SantosIn this paper we study the e¤ects of quality change on the price index for new passenger cars in Portugal for the years 1997-2001. Hedonic regression models are studied, giving particular emphasis to the relation between the form of the price index and the speci¤cation of the hedonic equation and estimation method used. The results indicate that the CPI component corresponding to this item may have been overestimated by as much as 2:2 percentage points per year. This corresponds to an overestimation of the overall CPI by about 0:15 percentage points per year. As a by-product of this analysis it is also possible to conclude that the quality of new cars sold in Portugal increased on average 4:8 percent per year during this period.
- Skills Dynamics and (the Need for) Longitudinal DataPublication . Lopes, Margarida Chagas; Fernandes, Graça LeãoSkills dynamics analyses are frequently carried on the basis of synchronic data, namely the one provided by firms' Employment Records. As this kind of surveys are designed to depict formal employment, not only separation spells but also most infra annual flows are not taken into consideration. Neither is there any data on vocational training and job experience, as well. Empirical evidence we have been obtaining from some previous research points both to the importance skills development strategies are taking along those non-employment spells and also to some qualification strategies which encompass both job-to-job and job-to-unemployment (inactivity) /unemployment (inactivity)-to-job flows. Also, analyses usually developed generally fail to take into consideration the influence exerted by economic cycles upon individual trajectories, in which skills development decisions are also supposed to play a major role. Therefore, we'll try to stress the adequacy both of duration models and longitudinal data on which those models should rely in order to shed light on the above mentioned features.
- On the Fisher-Konieczny index of price changes synchronizationPublication . Dias, D. A.; Marques, C. Robalo; Neves, P. D.; Silva, J. M. C. SantosThis note provides a structural interpretation for the index of price changes synchronization proposed by Fisher and Konieczny (2000, Economics Letters, 68, 271-277) and shows that it can be used to test the hypothesis of uniform staggering
- Time or state dependent price setting rules? Evidence from portuguese micro dataPublication . Marques, Carlos R.; Dias, Daniel; Silva, João SantosIn this paper we analyse the ability of time and state dependent price setting rules to explain durations of price spells or the probability of changing prices.Our results suggest that simple time dependent models cannot be seen as providing a reasonable approximation to the data and that state dependent models are required to fully characterise the price setting behaviour of Portuguese firms. Inflation, the level of economic activity and the magnitude of the last price change emerge as relevant variables a.ecting the probability of changing prices. Moreover, it is seen that the impact differs for negative and positive values of these covariates.
- Solving a Bi-objective Nurse Rerostering Problem by Using a Utopic Pareto Genetic HeuristicPublication . Pato, Margarida Vaz; Moz, MargaridaNurse rerostering arises when at least one nurse announces that she will be unable to undertake the tasks previously assigned to her. The problem amounts to building a new roster that satisfies the hard constraints already met by the current one and, as much as possible, fulfils two groups of soft constraints which define the two objectives to be attained. A bi-objective genetic heuristic was designed on the basis of a population of individuals characterised by pairs of chromosomes, whose fitness complies with the Pareto ranking of the respective decoded solution. It includes an elitist policy, as well as a new utopic strategy, introduced for purposes of diversification. The computational experiments produced promising results for the practical application of this approach to real life instances arising from a public hospital in Lisbon.
- Grasp and tabu search for redesigning web communitiesPublication . Colaço, Susana; Pato, Margarida VazWeb topologies are commonly characterised by hierarchical structures and highly unbalanced compositions, as illustrated by the difference of centrality and connectivity as to their elements. The major interest of the problem addressed in this paper lies in restructuring web communities to reduce these initial disequilibria so as to democratise information access or even for the purpose of preserving contents distributed on the Internet. Discussion of this issue thus leads to a hub location problem, formalised by network and integer programming models. Due to its highly complex nature, a GRASP and a tabu search heuristics were developed to find good quality feasible solutions to the problem. The set of test instances includes web communities obtained by crawling the web and using epistemic boundaries, as well as other randomly generated communities, built with specific network analysis software. The experiment demonstrated that the metaheuristics produced low costs and balanced structures, at least for the lower dimension web communities considered. All the redesigned web communities are more closely connected than before and the average distance among their elements reduced.
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