Resources for situated actions

In recent years, advances in software tools have made it easier to analyze interactive system specifications, and the range of their possible behaviors. However, the effort involved in producing the specifications of the system is still substantial, and a difficulty exists regarding the specification of plausible behaviors on the part of the user. Recent trends in technology towards more mobile and distributed systems further exacerbates the issue, as contextual factors come in to play, and less structured, more opportunistic behavior on the part of the user makes purely task-based analysis difficult. In this paper we consider a resourced action approach to specification and analysis. In pursuing this approach we have two aims - firstly, to facilitate a resource-based analysis of user activity, allowing resources to be distributed across a number of artifacts, and secondly to consider within the analysis a wider range of plausible and opportunistic user behaviors without a heavy specification overhead, or requiring commitment to detailed user models.We acknowledge with thanks EPSRC grant EP/F01404X/1 and FCT/FEDER grant POSC/EIA/56646/2004. Michael Harrison is grateful to colleagues in the ReSIST NoE (www.resit-noe.org)

Modelação 3D de uma mandíbula humana. Análise de elementos finitos em actividade mastigatória

A mandíbula humana é uma estrutura anatómica de grande complexidade biomecânica. Vários autores 1-3 desenvolveram malhas de elementos finitos, com diferentes graus de complexidade, para efectuar análise de tensões instaladas neste osso mediante determinadas condições. Pretendeu-se com este estudo optimizar a malha desenvolvida por Reis Campos2, através da inserção dos músculos envolvidos na mastigação

Estudo do comportamento mecânico dos compósitos de restauro dentário utilizando técnicas ópticas

Os materiais compósitos são hoje em dia cada vez mais utilizados no restauro dentário. Estes materiais substituíram as tradicionais amálgamas que apresentavam alguns inconvenientes. Apesar das vantagens no uso destes novos materiais existem ainda alguns problemas a resolver, nomeadamente a sua contracção durante o processo de cura. Desta forma surgem tensões nos dentes restaurados, podendo originar dano estrutural. Pretende-se com este trabalho estudar o processo de contracção dos compósitos dentários utilizando as técnicas ópticas, holografia digital, ESPI e correlação de imagem que demonstraram estar bem adaptadas a este estudo. É ainda apresentado um estudo comparativo utilizando diferentes materiais compósitos, bem como um estudo numérico com simulação por elementos finitos

Supporting resource-based analysis of task information needs

We investigate here an approach to modelling the dynamic information requirements of a user performing a number of tasks, addressing both the provision and representation of information, viewing the information as being distributed across a set of resources. From knowledge of available resources at the user interface, and task information needs we can identify whether the system provides the user with adequate support for task execution. We look at how we can use tools to help reason about these issues, and illustrate their use through an example.We also consider a full range of analyses suggested using this approach which could potentially be supported by automated reasoning systems.(undefined

Análise por elementos finitos do comportamento mecânico de uma mandíbula humana parcialmente edêntula em função da densidade óssea trabecular

Purpose: To present a methodological procedure to obtain the geometric and discrete models of a human mandible for numerical simulation of the biomechanical behavior of a partially edentulous mandible as a function of cancellous bone density. Methods: A 3D finite element method was used to assess the model of a partially edentulous mandible, Kennedy Class I, with dental implants placed at the region of teeth 33 and 43. The geometric solid model was built from CT-scan images and prototyping. In the discrete model a parametric analysis was performed to analyze the influence of cancellous bone density (25 %, 50 %, 75 %) on the development of mandibular stress and strain during simulation of masticatory forces in the anterior region. Results: Maximum von Mises stress and equivalent strain values in cancellous bone were found close to the loading area (masticatory forces). The peak stress and strain values occurred in the mandibular anterior region, and for the same masticatory force the equivalent stresses increased with bone density. Conclusion: The results suggest that the stresses and strains developed in the mandibular model were affected by cancellous bone density during the simulation of masticatory activity. Objetivo: Apresentar uma metodologia para modelamento geométrico de uma mandíbula humana e obtenção de um modelo discreto para simular numericamente o comportamento biomecânico de uma mandíbula parcialmente edêntula em função de diferentes densidades do osso trabecular. Metodologia: Utilizou-se o método de elementos finitos 3D para realizar um estudo numérico sobre um modelo de mandíbula humana, desdentada parcial tipo Classe I de Kennedy, com implantes nas regiões dos dentes 33 e 43. O modelo sólido geométrico foi determinado por tomografia computorizada e prototipagem. No modelo discretizado foi realizada uma análise paramétrica para verificar a influência da densidade óssea do osso trabecular (25 %, 50 %, 75 %) no desenvolvimento de tensões e deformações da mandíbula durante a aplicação de forças mastigatórias na região anterior. Resultados: As tensões máximas de von Mises e deformações equivalentes no osso trabecular foram desenvolvidas próximo às regiões de aplicação das forças de mordida. Os picos de valores de tensões/deformações localizaram-se na região anterior da mandíbula, sendo que, para o mesmo valor de esforço de mordida, as tensões equivalentes aumentaram com a densidade óssea. Conclusão: Os resultados sugerem que as tensões e deformações desenvolvidas no modelo mandibular testado foram afetadas pelo grau de densidade do osso trabecular durante simulação de atividade mastigatória

Mechanical behaviour of dental composite filling materials using digital holography

One of the most common clinical problems in dentistry is tooth decay. Among the dental filling materials used to repair tooth structure that has been destroyed by decay are dental amalgam and composite materials based on acrylics. Dental amalgam has been used by dentists for the past 150 years as a dental restorative material due to its low cost, ease of application, strength, durability, and bacteriostatic effects. However its safety as a filling material has been questioned due to the presence of mercury. Amalgam possesses greater longevity when compared to other direct restorative materials, such as, composite [1]. However, this difference has decreased with continual development of composite resins [2]

Bilinear R-parity violating SUSY: Neutrinoless double beta decay in the light of solar and atmospheric neutrino data

Neutrinoless double beta (\znbb) decay is considered within bilinear R-parity breaking supersymmetry, including the full one-loop corrections to the neutrino-neutralino mass matrix. Expected rates for \znbb decay in this model are discussed in light of recent atmospheric and solar neutrino data. We conclude that (a) tree-level calculations for \znbb decay within the bilinear model are not reliable in the range of parameters preferred by current solar and atmospheric neutrino problems. And (b) if the solar and atmospheric neutrino problems are to be solved within bilinear R-parity violating SUSY the expected rates for \znbb decay are very low; the effective Majorana neutrino mass at most 0.01 eV and typical values being one order of magnitude lower. Observing \znbb decay in the next round of experiments therefore would rule out the bilinear R-parity violating supersymmetric model as an explanation for solar and atmospheric neutrino oscillations, as well as any hierarchical scheme for neutrino masses, unless new neutrino interactions are present.Comment: 1 reference added, enlarged discussion of loop

Caso V: Osteoblastoma de Crânio

Trata-se de um caso de lesão craniana do qual nós recebemos a seguinte informação; Paciente do sexo feminino, de 34 anos de idade, que apresentava um tumor de consistência firme e de aumento progressivo na região temporal direita. Não sabemos por quanto tempo

Análisis de envejecimiento en paneles sándwich de madera/ Ageing tests study on wood-based sandwich panels

Los paneles sándwich de madera son un producto de creciente aplicación en la edificación de nuestro país. Este ascendente uso del material debe estar acompañado de las garantías necesarias avaladas por un estudio previo de sus prestaciones. Como es preceptivo y entre otros, se evalúa su durabilidad frente a las condiciones climatológicas, clave en los productos derivados de la madera, acorde a la normativa actual definida con tal fin, la Guía ETAG 016. Sin embargo, debido a la clase de uso del material, se ha detectado que dicha normativa tal y como está concebida no es capaz de valorar su envejecimiento adecuadamente. En este trabajo se proponen ensayos alternativos al establecido tras exhaustivos aná- lisis que recrean las condiciones reales de uso y más acordes a los productos de madera. Se concluye que la incorporación de una lámina impermeable, pero permeable al vapor de agua hacia el exterior, como las utilizadas en el montaje, aportan el mejor procedimiento de ensayo. Composite lightweight wood panels are being increasingly used in construction in Spain. Their growing use should be accompanied by necessary guarantees based on studies of their properties. As it is prescriptive and in addition to others tests, in the present work is examinated the durability of these panels when exposed to the climatic conditions, a characteristic of great importance for wood products, according to Guide ETAG 016, the current standard defining the ageing tests to be used. However, due to the use class of this material, there are indications that the testing outlined in this Guide is inappropriate for assessing the ageing of wood-based sandwich panels. Alternative tests are here proposed that recreate rather better the real conditions under which these products are used. Covering the samples in a waterproof sheeting permeable to the outward movement of water vapour, which is in fact used in the installation, provided the best procedure for testing these panels