2,849 research outputs found
Ground-motion simulation in the Lower Tagus Valley Basin
Throughout history, the Lower Tagus Valley (LTV) region has been shaken by several earthquakes, including some with moderate to large magnitudes and with sources located inside the basin, for example the 1344 (M6.0) and 1909 (M6.0) earthquakes. Previous simulations (Bezzeghoud et al. Natural Hazard 69:
1229–1245, 2011) have revealed strong amplification of the amplitude waves in the region, because of the effect of the low-velocity sediments that fill the basin. The model used in those simulations was updated in this work by including new high-resolution geophysical and geotechnical data available for the area (seismic reflection, aeromagnetic, gravimetric, deep wells, standard penetration tests, and geological data). To contribute to improved assessment of seismic hazard in the LTV, we simulated propagation of seismic waves produced by moderate earthquakes in a 3D heterogeneous medium by using elastic finite-difference wave propagation code. The method, successfully used by Grandin et al. (Geophys J Int 171: 1144–1161, 2007), involves evaluation of the seismic potential of known faults in the area studied and three-dimensional seismic ground motion modelling by use of finite difference methods. On the basis of this methodology, we calculated the ground motion for the April 23, 1909, Benavente (Portugal) earthquake (Mw = 6.0) in dense grid points, then computed the synthetic isoseismic map of the area by use of appropriate relationships between seismic intensity (MMI) and peak ground velocity (PGV). The synthetic results, in contrast with available macroseismic and instrumental data, enable validation of the source models proposed for the area, identification of the
sources of historical earthquakes, and could also indicate which areas are more exposed to seismic ground motion
Stellar equilibrium configurations of white dwarfs in the gravity
In this work we investigate the equilibrium configurations of white dwarfs in
a modified gravity theory, na\-mely, gravity, for which and
stand for the Ricci scalar and trace of the energy-momentum tensor,
respectively. Considering the functional form , with
being a constant, we obtain the hydrostatic equilibrium equation for
the theory. Some physical properties of white dwarfs, such as: mass, radius,
pressure and energy density, as well as their dependence on the parameter
are derived. More massive and larger white dwarfs are found for
negative values of when it decreases. The equilibrium configurations
predict a maximum mass limit for white dwarfs slightly above the Chandrasekhar
limit, with larger radii and lower central densities when compared to standard
gravity outcomes. The most important effect of theory for massive
white dwarfs is the increase of the radius in comparison with GR and also
results. By comparing our results with some observational data of
massive white dwarfs we also find a lower limit for , namely, .Comment: To be published in EPJ
Metodologia multi-critério para análise da qualidade acústica em igrejas
A premissa inicial para este estudo é que o conforto acústico global duma igreja, do ponto de vista do auditor, pode ser quantificado num índice único (denominado QAI Qualidade Acústica de Igrejas) a partir de parâmetros acústicos subjectivos, objectivos e até mesmo a partir de parâmetros arquitectónicos. Com base numa amostra de 13 igrejas foi desenvolvido um algoritmo para obtenção do QAI com base no método multi-critério aditivo simples, que agrega os valores de parâmetros acústicos subjectivos, sendo cada valor pesado de acordo com a importância que cada parâmetro assume no desempenho acústico global da igreja. O QAI pode ser obtido através de valores medidos insitu ou por valores previstos. Foram pois estabelecidos modelos de previsão para os parâmetros acústicos subjectivos a partir de parâmetros acústicos objectivos e/ou parâmetros arquitectónicos.The purpose of this research is to develop an algorithm that can translate the acoustic feeling transmitted to the receptor and that is able to quantify the global Acoustic Quality of a Church in a single index using either acoustic or architectural parameters. In order to quantify the Church Acoustic Quality index (QAI), subjective acoustic parameters were used so that the receptors perception of the acoustic behavior can be adequately translated. Using a multi-criteria method, and data from a sample of 13 churches, subjective acoustic parameters were associated with weight factors, whose values were calculated according to the relevance of each parameter in the acoustic behavior of the church. Prediction models were established to calculate the subjective acoustic parameters, using either objective acoustic parameters or architectural parameters
Yield and shelf life of chrysanthemum in response to the silicon application
The potted chrysanthemum is one of the main flowers produced in protected cultivation. Silicon has promoted improvements both in quantitative and qualitative aspects when supplied to some ornamental species produced in these conditions. We evaluated the response of chrysanthemum cultivars grown in pots to the application of silicon. The experiment was conducted in a greenhouse of the Universidade Federal de Viçosa, Minas Gerais state, Brazil. Treatments were arranged in a 3x2 factorial scheme (three cultivars of chrysanthemum: Coral Charm, White Reagan and Indianapolis and two doses of silicon: 0 and 800 mg kg-1) with six replications, in an entirely randomized design. We evaluated the diameter of the flower buds and stems; length of the flower stems; height of the plants; dry matter production of roots, leaves, stems, inflorescence and shoots; total number of inflorescences; diameter of the most fully open inflorescences; Si content in the leaf tissue; and flowering cycle and shelf life. The White Reagan cultivar produced the greatest number of inflorescences (29.17) per pot and proved to be more precocious (85.83 days). There was no negative interaction between Si, Ca and K and no effect of silicon was shown on the production and shelf life of the chrysanthemum. There was an increase in the content of this element in the leaves with the application of potassium metasilicate.O crisântemo de vaso é uma das principais flores produzidas em ambiente protegido. O silício tem promovido melhorias tanto no aspecto quantitativo quanto no qualitativo quando fornecido a algumas espécies ornamentais produzidas nestas condições. Assim, o objetivo desse trabalho foi avaliar a resposta à aplicação de silício de três cultivares de crisântemo cultivadas em vaso. O experimento foi conduzido em casa de vegetação da Universidade Federal de Viçosa. Os tratamentos foram dispostos em esquema fatorial 3x2 (três cultivares de crisântemo: Coral Charm, White Reagan e Indianápolis e duas doses de silício aplicadas no substrato: 0 e 800 mg kg-1) com seis repetições, em delineamento inteiramente casualizado. Foram avaliados o diâmetro dos botões e das hastes florais; comprimento das hastes florais; altura da planta; produção de matéria seca de raízes, folhas, caule, inflorescências e parte aérea; número total de inflorescências; diâmetro da inflorescência mais aberta; teor de Si nos tecidos foliares; ciclo e longevidade floral. A cultivar White Reagan produziu o maior número de inflorescências (29,17) por vaso e mostrou ser mais precoce (85,83 dias). Não houve interação negativa entre Si, Ca e K e não foi constatado efeito do silício na produção e na longevidade das inflorescências de crisântemo. Houve aumento nos teores deste elemento nas folhas com a aplicação do metasilicato de potássio
The development of an excellence model integrating the Shingo model and sustainability
Companies are continuously looking to improve their production systems using excellence models, with lean thinking, the Shingo model, six sigma and lean six sigma being the most comprehensive and applied. It is expected that the initial focus for the survival of companies is their economic profitability, but when economic needs are met, the next step is to achieve operational excellence. For this, in addition to economic objectives, it is necessary to include social and environmental objectives, i.e., the other two pillars of sustainability. This study aims to propose a conceptual model identifying the tools that can help achieve the desired results in the three pillars of sustainability aligned with operational excellence. The design of the conceptual model was based on a bibliometric analysis of the literature that relates the concepts of lean thinking, six sigma, lean six sigma and the Shingo model. The Web of Science was the platform selected for the collection of data, and the timeframe considered was 2010 to 2021. A total of 125 articles were analyzed using the VosViewer software, through which it was possible to analyze different topics of study related to the literature. The bibliometric analysis allowed for the identification of the temporal distribution of publications, the categorization of topics, different areas of application and the importance of the tools used in different practical cases. This study points out that companies have at their disposal several tools to achieve economic objectives. On the other hand, there is a set of more restricted tools that are used to meet the objectives of the social and environmental pillars. Future research should focus on identifying tools that meet social and environmental goals in order to strengthen these pillars that are essential for operational excellence and for the sustainability of companies.The work of the author Vanda Lima is supported by national funds, through the FCT-Portuguese Foundation for Science and Technology under the project UIDB/04728/2020
Drought tolerance conferred to sugarcane by association with Gluconacetobacter diazotrophicus: a transcriptomic view of hormone pathways
Sugarcane interacts with particular types of beneficial nitrogen-fixing bacteria that provide fixed-nitrogen and plant growth hormones to host plants, promoting an increase in plant biomass. Other benefits, as enhanced tolerance to abiotic stresses have been reported to some diazotrophs. Here we aim to study the effects of the association between the diazotroph Gluconacetobacter diazotrophicus PAL5 and sugarcane cv. SP70-1143 during water depletion by characterizing differential transcriptome profiles of sugarcane. RNA-seq libraries were generated from roots and shoots of sugarcane plants free of endophytes that were inoculated with G. diazotrophicus and subjected to water depletion for 3 days. A sugarcane reference transcriptome was constructed and used for the identification of differentially expressed transcripts. The differential profile of non-inoculated SP70-1143 suggests that it responds to water deficit stress by the activation of drought-responsive markers and hormone pathways, as ABA and Ethylene. qRT-PCR revealed that root samples had higher levels of G. diazotrophicus 3 days after water deficit, compared to roots of inoculated plants watered normally. With prolonged drought only inoculated plants survived, indicating that SP70-1143 plants colonized with G. diazotrophicus become more tolerant to drought stress than non-inoculated plants. Strengthening this hypothesis, several gene expression responses to drought were inactivated or regulated in an opposite manner, especially in roots, when plants were colonized by the bacteria. The data suggests that colonized roots would not be suffering from stress in the same way as non-inoculated plants. On the other hand, shoots specifically activate ABA-dependent signaling genes, which could act as key elements in the drought resistance conferred by G. diazotrophicus to SP70-1143. This work reports for the first time the involvement of G. diazotrophicus in the promotion of drought-tolerance to sugarcane cv. SP70-1143, and it describes the initial molecular events that may trigger the increased drought tolerance in the host plant
Tectonic and neotectonic implications of a new basement map of the Lower Tagus Valley, Portugal
In this paper we present a new basement (defined here as Paleozoic, Precambrian and Mesozoic igneous rocks) map of the Lower Tagus Valley area. This map
is a contribution to the understanding of the structural evolution of the top of the basement in the Lower Tagus Valley area during the Mesozoic and Cenozoic
Eras. The map was produced using aeromagnetic, well, seismic reflection and geological outcrop data. It shows unprecedented details of the geometry of the
basement rock's surface with higher resolution and covers a larger area than the previous basement map of the study area. In spite of an estimated average
error of 200 m in depth and an horizontal resolution of 4 km, our map not only reproduces with accuracy several well known basement structures but it also
emphasizes previously unknown features. Major basement faults were inferred from large depth variations at the top of the basement, magnetic 2D Euler
deconvolution and horizontal gradient analysis and are compatible with surface geological structures, well data and hydrogeological information. Implications
to the geodynamic evolution of the SW European Variscides and consequences to Meso-Cenozoic tectonics are discussed. The correlation of the basement
structures with instrumental seismicity is carried out and their neotectonic activity is discussed on the basis of existing geological outcrop data
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