Abduction in Well-Founded Semantics and Generalized Stable Models

Abductive logic programming offers a formalism to declaratively express and solve problems in areas such as diagnosis, planning, belief revision and hypothetical reasoning. Tabled logic programming offers a computational mechanism that provides a level of declarativity superior to that of Prolog, and which has supported successful applications in fields such as parsing, program analysis, and model checking. In this paper we show how to use tabled logic programming to evaluate queries to abductive frameworks with integrity constraints when these frameworks contain both default and explicit negation. The result is the ability to compute abduction over well-founded semantics with explicit negation and answer sets. Our approach consists of a transformation and an evaluation method. The transformation adjoins to each objective literal $O$ in a program, an objective literal $not(O)$ along with rules that ensure that $not(O)$ will be true if and only if $O$ is false. We call the resulting program a {\em dual} program. The evaluation method, \wfsmeth, then operates on the dual program. \wfsmeth{} is sound and complete for evaluating queries to abductive frameworks whose entailment method is based on either the well-founded semantics with explicit negation, or on answer sets. Further, \wfsmeth{} is asymptotically as efficient as any known method for either class of problems. In addition, when abduction is not desired, \wfsmeth{} operating on a dual program provides a novel tabling method for evaluating queries to ground extended programs whose complexity and termination properties are similar to those of the best tabling methods for the well-founded semantics. A publicly available meta-interpreter has been developed for \wfsmeth{} using the XSB system.Comment: 48 pages; To appear in Theory and Practice in Logic Programmin

Regulação da temperatura local da pele

Orientação: Paulo PaixãoO controlo da termorregulação assim, como o aquecimento e arrefecimento da pele influenciam o nível de fluxo sanguíneo a que a pele está sujeita. As alterações ou variações da temperatura local produzem um efeito de vasoconstrição ou de vasodilatação na pele. Este efeito, é o resultado de um conjunto de mecanismos como a activação dos receptores adrenérgicos, a resposta endotelial e sistemas sensoriais. Tanto a fase de vasodilatação como a fase de vasoconstrição da pele, são suportadas por transmissores simpáticos, e controlo nervoso local. Como consequência do aquecimento local verifica-se uma vasodilatação transitória através de um reflexo axonal, seguida de uma fase de “plateau”, em grande parte devido à presença de óxido nítrico. Após a fase de planalto ou “plateau” dá-se um fenómeno designado de “die-away”, que corresponde a uma lenta inversão da vasodilatação que está dependente dos nervos simpáticos vasoconstritores. A fase de vasoconstrição com consequente arrefecimento da temperatura local cutânea é originada por uma sobre-regulação pós-sináptica de α2C-adrenérgico, assim como pela inibição do sistema de óxido nítrico. [3] A termorregulação enquanto controlo da circulação sanguinea na pele humana é de extrema importância com vista a manter uma temperatura corporal normal durante variações da homeostase térmica. [2] Os principais objectivos desta monografia são efectuar uma revisão sobre a regulação da temperatura local da pele, abordando conceitos como a microcirculação cutânea identificando os locais onde se faz a regulação, passando pelo mecanismo de termorregulação local, comparando-o com o central, sem esquecer a importância do óxido nítrico em todo o processo. No que respeita à metodologia utilizada neste trabalho, esta recaiu essencialmente numa pesquisa bibliográfica utilizando o motor de busca pubmed, onde foi essencial a consulta de artigos recentemente publicados. Foram igualmente utilizadas outras fontes de informação como livros científicos relacionados com o tema

INFLUÊNCIA DO CLIMA ÉTICO SOBRE O COMPROMETIMENTO ORGANIZACIONAL DOS SERVIDORES DE UMA UNIVERSIDADE FEDERAL

O presente estudo teve como objetivo verificar se o clima ético influencia o comprometimento organizacional de servidores de uma universidade federal. Para tanto foi realizada uma pesquisa exploratória de abordagem quantitativa em que foi aplicado um questionário a 248 servidores. O instrumento foi formulado a partir de escalas internacionalmente reconhecidas e continha assertivas sobre clima ético e comprometimento organizacional. Os dados obtidos foram analisados com recursos de estatística descritiva e multivariada. A utilização da técnica de Análise Fatorial permitiu identificar quatro dimensões do clima ético e três dimensões do comprometimento organizacional. Os resultados obtidos com a aplicação da técnica de Regressão Múltipla confirmaram a influência do clima ético sobre o comprometimento organizacional. A dimensão Suporte do clima ético apresentou influência positiva sobre o componente Afetivo do comprometimento organizacional. Já o clima ético denominado Regras, Leis e Códigos afetou as dimensões Afetiva e Calculativa do comprometimento. Já o clima ético Sucesso e Eficiência mostrou-se um antecedente de influência positiva sobre o comprometimento Normativo

The use of the recognition heuristicas an investment strategy in European stock markets

Purpose – People often face constraints such as a lack of time or information in taking decisions, which leads them to use heuristics. In these situations, fast and frugal rules may be useful for making adaptive decisions with fewer resources, even if it leads to suboptimal choices. When applied to financial markets, the recognition heuristic predicts that investors acquire the stocks that they are aware of, thereby inflating the price of the most recognized stocks. This paper aims to study the profitability against the market of the most recognized stocks in Europe. Design/methodology/approach – In this paper, the authors perform a survey and use Google Trends to study the profitability against the market of the most recognized stocks in Europe. Findings – The authors conclude that a recognition heuristic portfolio yields poorer returns than a market portfolio. In contrast, from the data collected on Google Trends, weak evidence was found that strong increases in companies monthly search volumes may lead to abnormal returns in the following month. Research limitations/implications – The applied investment strategy does not account for transaction costs, which may jeopardize its profitability given the fact that it is necessary to revise the portfolio on a monthly basis. Despite the results obtained, they are useful to understanding the performance of recognition heuristic strategies over a comprehensive time horizon, and it would be interesting to depict its viability during different market conditions. This analysis could provide additional information about a preferable scenario for employing our strategies and, ultimately, enhance the profitability of recognition heuristic strategies. Practical implications – Through the exhaustive analysis performed here on the recognition heuristic in the European stock market, it is possible to conclude that no evidence was found for the viability of exploring this type of strategy. In fact, the investors would always gain better returns when adopting a passive investment strategy. Therefore, it would be wise to assume that the European market presents at least a degree of efficiency where no investment would yield abnormal returns following the recognition heuristic. Originality/value – The main objective of this paper is to study the performance of the recognition heuristic in the financial markets and to contribute to the knowledge in this field. Although many authors have already studied this heuristic when applied to financial markets, there is a lack of consensus in the literature.Propósito – Las personas a menudo enfrentan limitaciones como la falta de tiempo o de información para tomar decisiones, lo que las lleva a utilizar heurísticas. En estas situaciones, reglas rápidas y frugales pueden ser útiles para tomar decisiones adaptativas con menos recursos, incluso si conducen a elecciones subóptimas. Cuando se aplica a los mercados financieros, la heurística de reconocimiento predice que los inversores adquieren las acciones que conocen, inflando así el precio de las acciones más reconocidas. Este trabajo tiene como objetivo estudiar la rentabilidad frente al mercado de las acciones más reconocidas de Europa. Diseño/metodología/enfoque: en este artículo, los autores realizan una encuesta y utilizan Google Trends para estudiar la rentabilidad frente al mercado de las acciones más reconocidas de Europa. Hallazgos – Los autores concluyen que una cartera heurística de reconocimiento produce peores rendimientos que una cartera de mercado. Por el contrario, a partir de los datos recopilados en Google Trends, se encontró evidencia débil de que los fuertes aumentos en los volúmenes de búsqueda mensuales de las empresas pueden generar retornos anormales en el mes siguiente. Limitaciones/implicaciones de la investigación – La estrategia de inversión aplicada no tiene en cuenta los costos de transacción, lo que puede poner en peligro su rentabilidad dado que es necesario revisar la cartera mensualmente. A pesar de los resultados obtenidos, son útiles para comprender el desempeño de las estrategias heurísticas de reconocimiento en un horizonte temporal integral, y sería interesante representar su viabilidad en diferentes condiciones de mercado. Este análisis podría proporcionar información adicional sobre un escenario preferible para emplear nuestras estrategias y, en última instancia, mejorar la rentabilidad de las estrategias heurísticas de reconocimiento. Implicaciones prácticas – A través del análisis exhaustivo realizado aquí sobre la heurística de reconocimiento en el mercado de valores europeo, es posible concluir que no se encontró evidencia de la viabilidad de explorar este tipo de estrategia. De hecho, los inversores siempre obtendrán mejores rendimientos al adoptar una estrategia de inversión pasiva. Por lo tanto, sería prudente suponer que el mercado europeo presenta al menos un grado de eficiencia en el que ninguna inversión produciría rendimientos anormales siguiendo la heurística de reconocimiento. Originalidad/valor – El principal objetivo de este artículo es estudiar el desempeño de la heurística de reconocimiento en los mercados financieros y contribuir al conocimiento en este campo. Aunque muchos autores ya han estudiado esta heurística aplicada a los mercados financieros, existe una falta de consenso en la literatura

Hypothetical reasoning with well founded semantics

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New Optical Designs for Large Parabolic Troughs

The potential for cost reduction in parabolic troughs (PT) large collector fields is real and will be achieved in a variety of different ways. One problem certainly contributing to the costs of Solar Thermal Electricity (STE) PT fields is certainly the fact that large fields have a significant quantity of receiver lines and pipes bringing the heat transfer fluid to and off from them. The very large pipe length in large collector fields (for instance the 50MW fields in Spain) is a source of heat losses and parasitic losses due to significant pumping power, but also a source of other costs related to the number of pumps, to the amount of (costly) circulating fluid etc. In any given large field, receiver length and pipe length are determined by the aperture size of the PTs and one way to reduce these impacts on cost would be to increase aperture size. This has been the idea behind developments like the Ultimate Trough. In this paper new optical solutions are presented to obtain much larger troughs, using the same “standard” evacuated 70 mm inner radius tube, which in fact amounts to a substantial increase of concentration, but without sacrificing the acceptance angle of the optic. The Simultaneous Multiple Surface (SMS) method is used and practical solutions are obtained for apertures nearly close to twice the present standard of ≈ 6m width. The case of troughs for fixed receiver tubes is also discussed in this context. The solutions developed minimize transmission losses due to the glass cover and in that sense are an improvement on previous work. They also achieve a higher optical performance than other second stage solutions, because they are designed to eliminate optical losses through large gaps, something that is associated with the fact that the outer glass envelope has a much larger diameter than the inner receiver tube. The paper presents new examples of larger troughs with second stage concentrators, characterizing and comparing them with a “conventional” PT. The comparison is done for optical properties and for the energy collected on a sunny location (Faro, Portugal). The paper ends with a similar exercise done for fixed receiver troughs, an exercise that also leads to larger troughs (since it is done for the same 70 mm inner (evacuated) receiver tube) and concentration is increased. Again optical properties and energy performance are presented and compared with the conventional PT. The new solutions represent a potential reduction in field costs or even in O&M, as suggested, and this exercise will enable manufacturers the pondering of the manufacture of larger troughs (perhaps cheaper on a sqm basis) but with the extra cost of a secondary concentrator, knowing how much energy to expect from the adoption of solutions that benefit non-imaging optics design methods

Measuring Tourists Happiness: the case of the Algarve

Happiness and Quality of Life (QoL) have been receiving attention since many of the social ills have been reduced in the Western World. Happiness is considered one of the contributors to good QoL: if a community has happy citizens, their QoL is viewed as generally good (Veenhoven, 1997). In the same way, tourists’ happiness and QoL have become an important and interesting issue of research. However, measuring tourists’ happiness is a changeling problem. In this paper we present research on measuring tourists’ happiness. First, we have developed a model to explain the effect of different life domains on tourists’ happiness. Results indicated that both satisfaction with their family life and satisfaction with their jobs and activities play a significant role in determining overall happiness. After that, we have developed a model to identify which QoL factors influence tourists’ happiness. Results indicated that both present tourists’ QoL and QoL of their friends have a significant effect on tourists’ general happiness. A survey sample of tourists in the Algarve was used to test binary logistic regression models to detect factors affecting the probability of being at a specific level of happiness

Susceptibilidade de crianças asmáticas a infecções respiratórias

OBJECTIVE: A case-control study of patients with pneumonia was conducted to investigate whether wheezing diseases could be a risk factor. METHODS: A random sample was taken from a general university hospital in S. Paulo City between March and August 1994 comprising 51 cases of pneumonia paired by age and sex to 51 non-respiratory controls and 51 healthy controls. Data collection was carried out by two senior paediatricians. Diagnoses of pneumonia and presence of wheezing disease were independently established by each paediatrician for both cases and controls. Pneumonia was radiologically confirmed and repeatability of information on wheezing diseases was measured. Logistic regression analysis was used to identify risk factors. RESULTS: Wheezing diseases, interpreted as proxies of asthma, were found to be an important risk factor for pneumonia with an odds ratio of 7.07 (95%CI= 2.34-21.36), when the effects of bedroom crowding (odds ratio = 1.49 per person, 95%CI= 0.95-2.32) and of low family income (odds ratio = 5.59 against high family income, 95%CI= 1.38-22.63) were controlled. The risk of pneumonia attributable to wheezing diseases is tentatively calculated at 51.42%. CONCLUSION: It is concluded that at practice level asthmatics should deserve proper surveillance for infection and that at public health level pneumonia incidence could be reduced if current World Health Organisation's guidelines were reviewed as to include comprehensive care for this illness.OBJETIVO: Investigar, através de um estudo caso-controle de pacientes com pneumonia, se as doenças chiadoras poderiam constituir-se em fator de risco. MÉTODOS: De um hospital universitário, na cidade de São Paulo, Brasil, entre março e agosto de 1994, foi tomada uma amostra de 51 casos de pneumonia pareados por sexo e idade a 51 controles sadios e 51 controles não respiratórios. O diagnóstico de pneumonia e a presença de doença chiadora foram investigados de forma independente por cada pediatra tanto para casos quanto para controles. Foi confirmada pneumonia radiologicamente e a repetibilidade da informação sobre doença chiadora foi medida. Foi utilizada regressão logística para identifição de riscos. RESULTADOS: As doenças chiadoras, entendidas como representantes de asma, mostraram ser importante fator de risco para pneumonia, com um odds ratio de 7,07 (IC95%= 2,34-21,36), controlados os efeitos de aglomeração no quarto de dormir (odds ratio de 1,49 por pessoa a mais no quarto, IC95%= 0,95-2,32) e a baixa renda familiar (odds ratio de 5,59 contra alta renda familiar, IC95%= 1,38-22,63). O risco atribuível às doenças chiadoras foi calculado de forma exploratória em 51,42%. CONCLUSÃO: Conclui-se que os clínicos devem ter atenção sobre asmáticos para o risco de infecção e que ao nível da saúde pública a incidência de pneumonia poderia ser reduzida se as orientações atuais da Organização Mundial da Saúde pudessem ser revistas para oferecer atenção integral para os doentes

Instrumentos avaliativos: da criação a validação e aplicação

A proposta da obra Construção e Validação de Instrumentos de Avaliação: da teoria a exemplificação prática é apresentar produtos do Programa de Pós-Graduação em Avaliação (PPGA) da Fundação Cesgranrio. A intenção das pesquisas copiladas na obra é demonstrar a amplitude de possibilidades da ação de avaliar, validar e reavaliar instrumentos para coleta de dados. O leitor poderá conhecer aspectos da teoria que embasam o tema avaliação, bem como explorar os componentes que cercam o planejamento do trabalho, a aplicação de instrumentos, a própria ação de avaliar e a devolutiva dos resultados