A multiparameter family of irreducible representations of the quantum plane and of the quantum Weyl algebra

We construct a family of irreducible representations of the quantum plane and of the quantum Weyl algebra over an arbitrary field, assuming the deformation parameter is not a root of unity. We determine when two representations in this family are isomorphic, and when they are weight representations, in the sense of Bavula.Comment: 12 pages, Section 2 has been reorganized, new material added in a new Section

Diagnóstico participativo em comunidades ribeirinhas na Amazônia: peixes e sua ecologia.

Este trabalho teve o objetivo de levantar o conhecimento do ribeirinho sobre a ecologia dos peixes em relação ao hábito alimentar, e quais as principais plantas utilizadas como alimento para estas populações locais por meio de oficinas participativas

INJECTABLE HYBRID SYSTEM FOR STRONTIUM LOCAL DELIVERY TO PROMOTE BONE REGENERATION

In bone tissue regeneration strategies, injectable bone substitutes are very attractive since they can be applied with minimally invasive surgical procedures and can perfectly fill irregular defects created in cases of trauma, infection or tumor resection. These materials must combine adequate mechanical properties with the ability to induce new bone formation. Incorporating strontium (Sr) in bone substitute biomaterials may be a strategy to achieve high Sr concentrations, not in a systemic but in a local environment, taking advantage of the osteoanabolic and anti-osteoclastic activity of Sr, for the enhancement of new bone formation. In this context, the aim of the present work was to evaluate the response of a Sr-hybrid injectable system for bone regeneration, designed by our group, consisting of hydroxyapatite microspheres doped with Sr and an alginate vehicle crosslinked in situ with Sr, in an in vivo scenario. Two different animal models were used, rat (Wistar) and sheep (Merino Branco) critical sized bone defect. Non Sr-doped similar materials (Ca-hybrid) or empty defects were used as control. Sr-hybrid system led to an increased bone formation in both center and periphery of a rat critical sized defect compared to a non Sr–doped similar system, where new bone formation was restricted to the periphery. Moreover newly formed bone was identified as early as one week after its implantation in a sheep model. After eight weeks, the bone surrounded the microspheres, both in the periphery and in the center of the defect. Most importantly, the hybrid system provided a scaffold for cell migration and tissue ingrowth and offered structural support, as observed in both models. The effective improvement of local bone formation suggests that this might be a promising approach for bone regeneration, especially in osteoporotic conditions

Seismic assessment of masonry “Gaioleiros” buildings in Lisbon, Portugal

This paper presents a numerical study for the seismic assessment of a Portuguese building masonry typology - “Gaioleiro”. Numerical analysis was performed using a finite element model calibrated with experimental results obtained in 1:3 reduced scale tests carried out in the LNEC 3D shaking table. Non-linear dynamic analysis with time integration and pushover analysis are carried out. Using nonlinear dynamic analysis it was verified that the buildings of “gaioleiro” type with appropriate floor-wall connections are in the limit of their loading capacity. The pushover analyses performed in this study were incapable of simulating correctly the damage of the structure under seismic action.The authors are grateful to the National Laboratory of Civil Engineering for providing the experimental data for the shaking table tests. The present work is partly funded by FCT (Portuguese Foundation for Science and Technology), through project POCI/ECM/61671/2004, "Seismic vulnerability reduction of old masonry buildings'' and PhD grant SFRH/BD/32190/2006

Avaliação da segurança sísmica de edifícios antigos

As construções antigas de alvenaria apresentam propriedades particulares (baixa resistência à tracção e ausência de pavimentos rígidos) que fazem com que a avaliação da segurança sísmica de edifícios antigos seja complexa. Esta comunicação apresenta uma muito breve revisão sobre a análise sísmica de estruturas de alvenaria sem diafragmas rígidos, juntamente com casos de estudo, com o objectivo de realçar a necessidade de formação específica nesta área. Nos exemplos apresentados são utilizados diferentes métodos de análise avançada. Os resultados demonstram a necessidade de utilizar ferramentas de análise não-linear para esta avaliação de segurança

Comparison of different seismic non-linear analyses of an ancient masonry building

This paper presents a study about the possibilities of non-linear static analyses for evaluating the seismic performance of ancient masonry buildings. The adopted case study is a Portuguese typology of the 19th century. Non-linear dynamic and static analyses were carried out using a numerical model calibrated with experimental results obtained in 1:3 reduced scale tests made in a 3D shaking table. In the non-linear dynamic analysis with time integration, the earthquakes are composed by two uncorrelated artificial accelerograms compatible with the elastic response spectrum defined by Eurocode 8. Using this analysis it was verified that the adopted building, with appropriate floor-wall connections, is in the limit of its loading capacity. In the non-linear static analyses (pushover), lateral load distributions proportional to the mass and 1st mode shape in the applicable direction were considered. In an attempt to explore the pushover analyses proportional to the 1st mode shape, adaptive pushover analyses were carried out, in which the load distribution was updated as a function of the existing damage. It is concluded that the pushover analysis does not simulate correctly the failure mode of the structure, namely the out-of-plane mechanism, and should be used with caution

Evaluation of the seismic performance of masonry buildings of the type “Gaioleiro”, Lisbon (Portugal)

This paper presents the numerical study that aims at the seismic evaluation of the performance of typical Portuguese “gaioleiro” buildings. The numerical modeling was performed with resource to a model of finite elements on 1:3 reduced scale and it was calibrated in agreement with experimental results obtained in the tests done in the LNEC 3D shaking table. With the purpose to define an adequate strategy for seismic performance evaluation nonlinear dynamical analysis with time integration and pushover analyses were carried out. In the dynamic analysis, each earthquake is composed by two uncorrelated artificial accelerograms compatible with design response spectrum of EC8. In the pushover analyses it was considered that the seismic action is simulated through a set of proportional horizontal forces to the mass of structure and to the 1st vibration mode according with the direction in study

Seismic performance of ancient masonry buildings: a sensitivity analysis

Ancient masonry structures are usually associated to a high seismic vulnerability, mainly due to the properties of the materials (low tensile and moderate shear strengths), weak connections between floors and load-bearing walls, high mass of the masonry walls and flexibility of the floors. For these reasons, the seismic performance of traditional masonry structures has received much attention in the last decades. This paper presents the sensitivity analysis taking into account the deviations on features of the “gaioleiro” buildings - Portuguese building typology. The main objective of the sensitivity analysis is to compare the seismic performance of the structure as a function of the variations of its properties with respect to the response of a reference model. The sensitivity analysis was carried out for two types of structural analysis, namely for the non-linear dynamic analysis with time integration and for the pushover analysis proportional to the mass of the structure. The Young’s modulus of the masonry walls, Young’s modulus of the timber floors, the compressive and tensile non-linear properties (strength and fracture energy) were the properties considered in both type of analysis. Additionally, in the dynamic analysis, the influences of the viscous damping and of the vertical component of the earthquake were evaluated. Finally, a pushover analysis proportional to the modal displacement of the first mode in each direction was also carried out. The results shows that the Young’s modulus of the masonry walls, the Young’s modulus of the timber floors and the compressive non-linear properties are the parameters that most influence the seismic performance of the structure for both sensitivity analyses. Furthermore, it is concluded that that the stiffness of the floors influences significantly the strength capacity and the collapse mechanism of the numerical model, and the strengthening of the timber floors improved significantly the seismic performance of the ancient masonry buildings with flexible floors.(undefined

Seismic vulnerability of existing masonry buildings: Nonlinear parametric analysis

Existing masonry structures are usually associated to a high seismic vulnerability, mainly due to the properties of the materials, weak connections between floors and load-bearing walls, high mass of the masonry walls and flexibility of the floors. For these reasons, the seismic performance of existing masonry structures has received much attention in the last decades. This study presents the parametric analysis taking into account the deviations on features of the gaioleiro buildings - Portuguese building typology. The main objective of the parametric analysis is to compare the seismic performance of the structure as a function of the variations of its properties with respect to the response of a reference model. The parametric analysis was carried out for two types of structural analysis, namely for the non-linear dynamic analysis with time integration and for the pushover analysis with distribution of forces proportional to the inertial forces of the structure. The Young's modulus of the masonry walls, Young's modulus of the timber floors, the compressive and tensile non-linear properties (strength and fracture energy) were the properties considered in both type of analysis. Additionally, in the dynamic analysis, the influences of the vis-cous damping and of the vertical component of the earthquake were evaluated. A pushover analysis proportional to the modal displacement of the first mode in each direction was also carried out. The results shows that the Young's modulus of the masonry walls, the Young's modulus of the timber floors and the compressive non-linear properties are the pa-rameters that most influence the seismic performance of this type of tall and weak existing masonry structures. Furthermore, it is concluded that that the stiffness of the floors influences significantly the strength capacity and the collapse mecha-nism of the numerical model. Thus, a study on the strengthening of the floors was also carried out. The increase of the thickness of the timber floors was the strengthening technique that presented the best seismic performance, in which the reduction of the out-of-plane displacements of the masonry walls is highlighted.(undefined