1,178 research outputs found

    The nature of the LINER in the galaxy NGC 404

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    NGC 404, at a distance of 3.4 Mpc, is the nearest S0 galaxy. This galaxy harbors a LINER; however, since the spectrum does not show a broad H{\alpha} emission, it is not certain that this LINER is a low luminosity AGN and its nature is still an open question. HST observations show the existence of stellar populations with an age of 3 x 10^8 years years in the galactic bulge and with an age of 6-15 x 10^9 years in the galactic disk. In this work, we present an analysis of the data cube of NGC 404 obtained with the IFU (Integral Field Unity) of the GMOS (Gemini Multi-Object Spectrograph) on the Gemini North telescope.Comment: 2 pages, 2 figure

    Comportamento sísmico da igreja do Mosteiro dos Jerónimos

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    Para avaliar o comportamento sísmico da Igreja do Mosteiro dos Jerónimos tendo em vista o diagnóstico das suas capacidades e vulnerabilidades estruturais bem como a avaliação da segurança sísmica para cenários de diferente perigosidade, foram realizadas um conjunto de análises numéricas estáticas e dinâmicas, admitindo comportamento não linear material e geométrico, cujos resultados se apresentam. A investigação numérica é antecedida pela caracterização (quantitativa e qualitativa) da construção e pela caracterização da acção sísmica com base em estudos de casualidade e em modelos sismológicos. A realização das análises dinâmicas não lineares, no domínio do tempo, é efectuada para acções sísmicas correspondentes a cenários com 475, 975 e 5000 anos de período de retorno e visa caracterizar o desempenho sísmico da Igreja, nomeadamente das potenciais vulnerabilidades identificadas. Para ao efeito, realiza-se previamente, um conjunto de análises estáticas, lineares e não lineares, e análises dinâmicas modais. As análises dinâmicas modais e as análises estáticas, sob a acção das cargas verticais permanentes, são utilizadas para a calibração/validação do modelo numérico. As análises estáticas lineares equivalentes à acção sísmica são utilizadas para uma estimativa prévia da exigência sísmica (incluindo a localização potencial das incidências não lineares) e das vulnerabilidades virtuais associadas. As análises estáticas não lineares (do tipo “pushover”) são utilizadas para estimar a capacidade da construção sob acções horizontais e para identificar os potenciais mecanismos de colapso. De acordo com os resultados das análises dinâmicas realizadas, para os cenários sísmicos com 475 e 975 anos de período de retorno, a Igreja ficará sob importantes estados de tensão e de fendilhação não sendo expectável a sua ruína parcial ou global. Para os cenários de perigosidade sísmica mais severos, correspondentes a 5000 anos de período de retorno, identificou-se uma potencial incidência de danos nos pilares da nave da Igreja cuja ruína conduz ao colapso da abóbada da nave

    Risk assessment due to terrorist actions: A case study in Lisbon

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    The occurrence of unanticipated extreme events in modern societies typically induces significant damage and losses to the built heritage and people, but also concern and fear in the population. The capacity of structures to resist to extreme events has been deserving the attention of researchers during the last decades. The occurrence of explosion-based terrorist attacks in the last two decades has caused a great concern among decision makers and had led to important investments towards the characterization of the structural response of buildings subjected to blast loads. The work presented in this paper was performed in collaboration with one of the largest Public Transportation Operators in Portugal and addresses the problem of risk assessment due to terrorist actions in the case of external explosions, and structural safety evaluation of buildings when subjected to different explosion scenarios.This work was supported by FCT (Portuguese Foundation for Science and Technology) under Project CHSECURE (PTDC/EMC/120118/2010), and within ISISE, project UID/ECI/04029/2013. The first author also acknowledges the support from his PhD FCT grant with the reference SFRH/BD/45436/2008

    Development of bioplastics from agro-wastes

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    During centuries synthetic polymers have been used in a variety of applications in the everyday of human life. They became essential due to its versatility, durability and low cost [1]. However, due to their excessive use, several drawbacks as its resistance to the decomposition, toxicity after incineration and accumulation in the environment induce negative ecological impact in landfills and water contamination [2]. Moreover, plastics production implies the use of non-renewable resources, such as, oil and natural gas that represents about 8 % of global consumption [1,2]. Therefore, become crucial to search for new ecological materials toward innovative and cost-effective fabrication of environmentally degradable plastics demonstrating similar performance to conventional ones [1,3]. Simultaneously, the high amount of agro-wastes generated from food industry have been a growing concern, around 1.3 billion tons are leftover, which became an environmental and financial issue [1]. Among these agro-waste stands out, food waste, halum and stems of vegetables/fruits, grains and seeds, from which it is possible to obtain natural polymers [3]. Biopolymers exhibit unique properties and can be produced from plants and crops wastes. Rubber, proteins, starch and cellulose are some of the examples [4]. Cellulose has been used for the production of biopolymers, nevertheless, because of the difficulty inherent in its extraction process, various methods have been studied in order to optimize this process. Currently, cellulose derivatives are used, which is an example of cellulose acetate, whose chemical purification process is quite costly and lengthy [1]. Thus, the present work, aims to directly synthetize biopolymers from agro-wastes. Green chemistry methodology is applied to extract natural polymers, such as cellulose, from vegetable wastes. Structural, morphological and mechanical characterization of the produced materials are accessed and compared with conventional synthetic polymers. Also, biodegradability assays will be performed to check the microorganisms’ capability to assimilate the produced bioplastics

    Seismic safety assessment of the church of Monastery of Jerónimos, Portugal

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    Preservation of historical constructions with high cultural heritage value is an actual theme in modern societies as these constructions play an important role in the industry of tourism and culture, and consequently in the economy and in the image of countries and self-esteem of people. The seismic hazard of Portugal and, due to its vicinity, of the Mediterranean basin puts under potential risk of damage and collapse a high number of historical constructions, namely most of the old masonry constructions, particularly vulnerable to seismic actions. The seismic behaviour of the Church of Monastery of Jerónimos, Portugal, is discussed here with a numerical simulation, using artificial seismic acceleration time histories in agreement with three seismic hazard scenarios for 475, 975 and 5000 years return periods, allowing to assess its seismic safety

    Possibilidades de intervenção estrutural para mitigar o risco sísmico da Igreja do Mosteiro dos Jerónimos

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    De acordo com um diagnóstico previamente estabelecido, o comportamento dinâmico da Igreja do Mosteiro dos Jerónimos, para acções horizontais, é condicionado pelo comportamento dos pilares da nave que aparecem como os elementos mais vulneráveis [1]. Os resultados de simulações numéricas do comportamento sísmico da Igreja sugerem mesmo a possibilidade de colapso dos pilares para cenários de casualidade sísmica com períodos de retorno iguais ou superiores a 5000 anos. Os resultados para estes cenários sugerem também a eminência de colapso do campanário da torre Sul. Neste contexto, tendo presente o elevado valor patrimonial do monumento – Igreja do Mosteiro dos Jerónimos – apresentam-se neste trabalho um conjunto de possibilidades de intervenção estrutural, compatíveis com o valor arquitectónico da construção, com vista à melhoria do desempenho dinâmico e à mitigação do risco sísmico da Igreja. As soluções de intervenção propostas visam essencialmente a melhoria do desempenho sísmico dos pilares, pela incidência das vulnerabilidades detectadas no diagnóstico e pela sua importância na segurança global da nave da Igreja. Com base em resultados de ensaios de simulação numérica, discutem-se as vantagens e as desvantagens das diferentes estratégias de solução e indica-se aquela que conduz ao melhor desempenho dos pilares de forma a salvaguardar a integridade estrutural da Igreja para aqueles cenários sísmicos

    Nonlinear dynamic analysis for safety assessment of heritage buildings: Church of Santa Maria de Bélem

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    Despite the remarkable longevity of heritage constructions, they typically present several structural fragilities inherent to their own material and constructive features. This fact is particularly relevant when seismic loads are concerned, because a very significant portion of such constructions lack adequate seismic resistance and require retrofitting interventions in order to mitigate their vulnerability. However, to guarantee the success of the interventions, the interventions should be carefully selected based on a full understanding of the dynamic response of the building and, particularly, its most vulnerable structural elements. Due to many reasons, the issues associated with this kind of analysis are still difficult to address; therefore, research on this subject should be encouraged. Taking this into account, the church of Santa Maria de Belem, one of the most emblematic buildings of the monastery of Jeronimos complex in Lisbon, is used in this work as a case study to discuss the nonlinear dynamic response of cultural heritage buildings. The nonlinear dynamic behavior of the church was numerically simulated with a three-dimensional (3D) model using artificially generated seismic acceleration time histories, in agreement with seismic hazard scenarios for return periods of 475, 975, and 5,000 years. The dynamic response of the church is discussed and a comparison against results derived from a pushover analysis is also presented. Finally, a modal analysis is presented, estimating the damage level that would be present in the church after the occurrence of such seismic scenarios.This work was partly financed by European Regional Development Fund (ERDF) funds through the Operational Programme Competitiveness Factors (COMPETE) and by national funds through the Foundation for Science and Technology (FCT) within the scope of project POCI-01-0145-FEDER-007633. The authors are also grateful to three anonymous reviewers whose comments significantly improved the clarity of the paper

    Seismic assessment of St. James church by means of pushover analysis : before and after the New Zealand earthquake

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    The paper presents a numerical study for the seismic assessment of the St James Church in Christchurch, New Zealand affected by the recent 2011 earthquake and subsequent aftershocks. The structural behaviour of the Church has been evaluated using the finite element modelling technique, in which the nonlinear behaviour of masonry has been taken into account by proper constitutive assumptions. Two numerical models were constructed, one incorporating the existing structural damage and the other considering the intact structure. The validation of the numerical models was achieved by the calibration of the damaged model according to dynamic identification tests carried out in situ after the earthquake. Non-linear pushover analyses were carried out on both principal directions demonstrating that, as a result of the seismic action, the Church can no longer be considered safe. Pushover analysis results of the undamaged model show reasonable agreement with the visual inspection performed in situ, which further validates the model used. Finally, limit analysis using macro-block analysis was also carried out to validate the main local collapse mechanisms of the Church.(undefined

    Nitrogen compounds prevent H9c2 myoblast oxidative stress-induced mitochondrial dysfunction and cell death

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    Oxidative stress has been connected to various forms of cardiovascular diseases. Previously, we have been investigating the potential of new nitrogen-containing synthetic compounds using a neuronal cell model and different oxidative stress conditions in order to elucidate their potential to ameliorate neurodegenerative diseases. Here, we intended to extend these initial studies and investigate the protective role of four of those new synthetic compounds (FMA4, FMA7, FMA762 and FMA796) against oxidative damage induced to H9c2 cardiomyoblasts by tert-butylhydroperoxide (t-BHP). The data indicates that FMA762 and FMA796 decrease t-BHP-induced cell death, as measured by both sulforhodamine B assay and nuclear chromatin condensation evaluation, at non-toxic concentrations. In addition, the two mentioned compounds inhibit intracellular signalling mechanisms leading to apoptotic cell death, namely those mediated by mitochondria, which was confirmed by their ability to overcome t-BHP-induced morphological changes in the mitochondrial network, loss of mitochondrial membrane potential, increased expression of the pro-apoptotic proteins p53, Bax and AIF and activation of caspases-3 and -9. Importantly, our results indicate that the compounds’ ROS scavenging ability plays a crucial role in the protection profile, as a significant decrease in t-BHP-induced oxidative stress occurred in their presence. Data obtained indicates that some of the test compounds may clearly prove valuable in a clinical context by diminishing cardiac injury associated to oxidative stress without any toxicity.Fundação para a Ciência e a Tecnologia (FCT) - Bolsa SFRH/BD/17174/2004, PTDC/QUI/ 64358/200
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