7,660 research outputs found
Light clusters and the pasta phase
The effects of including light clusters in nuclear matter at low densities
are investigated within four different parametrizations of relativistic models
at finite temperature. Both homogeneous and inhomogeneous matter (pasta phase)
are described for neutral nuclear matter with fixed proton fractions. We
discuss the effect of the density dependence of the symmetry energy, the
temperature and the proton fraction on the non-homogeneous matter forming the
inner crust of proto-neutron stars. It is shown that the number of nucleons in
the clusters, the cluster proton fraction and the sizes of the Wigner Seitz
cell and of the cluster are very sensitive to the density dependence of the
symmetry energy.Comment: 14 pages, 14 figures; Accepted for publication in Phys. Rev.
Ethnobiology and health among the Kulina People from the Upper Envira River, State of Acre, Brazil.
This article is about an ethnobiological and ethnoecological research among Kulina People from the Upper Envira River, located in the Amazon Region, State of Acre, Brazil. The data was collected during two work trips to 10 villages of three Indian Lands (IL) in 2008 and 2009. The field work was based on participant observation, open, semi-structured and structured interviews and walk-in-the-woods technique. The total population was 423 distributed in 77 dwellings. The gender proportion is 49,7% of women to 50,3% of men. Fifty one per cent are under 15 years old. The most important health problems are respiratory and digestive signs and symptoms, dermatosis and ophidian attacks. Kulina diet is based on cultivated foods, hunt and fishes. There is a variety of fruits collected in the forest. The cultivation system has high biodiversity and is about 1 ha. We recorded 193 medicinal plants species to a large number of purposes. The number of species recorded, indications by Kulina about properties and potential uses to health for these plants indicate an important ethnobotanic knowledge and requires new researches among them. We calculate that a great number of species is yet to register.Special issue: Medical Ethnobiology
Distinguishing the albedo of exoplanets from stellar activity
Light curves show the flux variation from the target star and its orbiting
planets as a function of time. In addition to the transit features created by
the planets, the flux also includes the reflected light component of each
planet, which depends on the planetary albedo. This signal is typically
referred to as phase curve and could be easily identified if there were no
additional noise. As well as instrumental noise, stellar activity, such as
spots, can create a modulation in the data, which may be very difficult to
distinguish from the planetary signal. We analyze the limitations imposed by
the stellar activity on the detection of the planetary albedo, considering the
limitations imposed by the predicted level of instrumental noise and the short
duration of the observations planned in the context of the CHEOPS mission. As
initial condition, we have assumed that each star is characterized by just one
orbiting planet. We built mock light curves that included a realistic stellar
activity pattern, the reflected light component of the planet and an
instrumental noise level, which we have chosen to be at the same level as
predicted for CHEOPS. We then fit these light curves to try to recover the
reflected light component, assuming the activity patterns can be modeled with a
Gaussian process.We estimate that at least one full stellar rotation is
necessary to obtain a reliable detection of the planetary albedo. This result
is independent of the level of noise, but it depends on the limitation of the
Gaussian process to describe the stellar activity when the light curve
time-span is shorter than the stellar rotation. Finally, in presence of typical
CHEOPS gaps in the simulations, we confirm that it is still possible to obtain
a reliable albedo.Comment: Accepted for publication in A&A, 14 pages, 12 figure
Cultivo da soca de arroz irrigado: uma alternativa para o aumento da rentabilidade da rizicultura do baixo São Francisco.
bitstream/item/82087/1/CPATC-COM.-TEC.-32-99.pd
Modeling of tension–compression asymmetry and orthotropy on metallic materials: numerical implementation and validation
The details concerning the implementation of the yield criterion developed by Cazacu et al. 2006 (CPB06), which accounts for both tension–compression asymmetry and orthotropy of the plastic flow, in the fully implicit FE solver DD3IMP (contraction of ‘Deep Drawing 3-D IMPlicit') are presented in this work. The implemented constitutive model is extensively described, including the analytical first and second order derivatives required to the stress update algorithm. A set of anisotropy parameters describing the mechanical behavior of two metallic materials at room temperature, namely Zirconium and AZ31-Mg alloy, are identified with the DD3MAT (contraction for ‘Deep Drawing 3-D MATerial’) in-house code (Alves, 2004) [2]. The anisotropy parameters are identified for both the CPB06 and the Cazacu and Barlat (2001) (CB2001) yield criteria, in order to emphasize the importance and role of the strength differential effect. The results clearly show that the CPB06 yield criterion is able to accurately describe both the in-plane anisotropy and tension–compression asymmetry, as well a different anisotropic behavior in uniaxial tension and uniaxial compression. The numerical simulation of a four-point bending test is performed, considering different orientations of the beam, i.e. of the hard/soft to deform direction relatively to the load direction, allowing to validate the implementation. The results obtained with the CPB06 show its ability to describe with accuracy the strain fields in the beam's central cross-section, the distribution of the tensile and compressive layers and, consequently, the shift of the neutral layer. The
comparison with the results obtained with CB2001 indicates that the strength differential effect affects
the final deformed shape of the beam, particularly for materials exhibiting strong tension–compression
asymmetry.The authors gratefully acknowledge the financial support of the Portuguese Foundation for Science and Technology (FCT), Portugal via the projects PTDC/EME-TME/118420/2010, UID/EMS/00285/2013 and by FEDER, Portugal funds through the program COMPETE - Programa Operational Factores de Competitividade, under the project CENTRO-07-0224-FEDER-002001 (MT4MOBI). The first author is also grateful to the FCT for the Ph.D. Grant SFRH/BD/98545/2013.info:eu-repo/semantics/publishedVersio
DD3MAT: a code for yield criteria anisotropy parameters identification
This work presents the main strategies and algorithms adopted in the DD3MAT in-house code, specifically developed for identifying the anisotropy parameters. The algorithm adopted is based on the minimization of an error function, using a downhill simplex method. The set of experimental values can consider yield stresses and r - values obtained from in-plane tension, for different angles with the rolling direction (RD), yield stress and r - value obtained for biaxial stress state, and yield stresses from shear tests performed also for different angles to RD. All these values can be defined for a specific value of plastic work. Moreover, it can also include the yield stresses obtained from in-plane compression tests. The anisotropy parameters are identified for an AA2090-T3 aluminium alloy, highlighting the importance of the user intervention to improve the numerical fit.The authors gratefully acknowledge the financial support of the Portuguese Foundation for Science and Technology (FCT) via the projects PTDC/EME-TME/118420/2010 and UID/EMS/00285/2013. The first author is also grateful to the FCT for the PhD grant SFRH/BD/98545/2013.info:eu-repo/semantics/publishedVersio
Análise da atividade florestal no Pará através da matriz de contabilidade social.
As indústrias de base florestal e de madeira processada mecanicamente possuem relevância na economia brasileira, pois participaram na formação do Produto Interno Bruto (PIB) em 2006 com 4,7% e geraram 10,6 milhões de empregos (ABIMCI, 2007). No âmbito estadual, o Pará se destaca com produtos extrativos da floresta tropical, principalmente da madeira em tora, cuja participação, em 2005, foi de 57,2% do total de 17.372.428 m3 produzidos no País (IBGE, 2006). Frente a esse cenário, este estudo teve como objetivo analisar a importância socioeconômica das atividades florestal e de madeira e mobiliário no Pará, através do modelo da Matriz de Contabilidade Social (MCS) do ano de 1999. Os resultados revelaram que as atividades de base florestal foram consideradas atividades-chave, por apresentarem efeito de linkages para frente e/ou para trás superior a um. Todavia, em função do ajuste da legislação ambiental em vigor, as atividades de base florestal terão que implementar novos padrões de produção sustentáveis, atendendo as exigências dos mercados nacional e internacional
Thermodynamic and dynamic anomalies for a three dimensional isotropic core-softened potential
Using molecular dynamics simulations and integral equations (Rogers-Young,
Percus-Yevick and hypernetted chain closures) we investigate the thermodynamic
of particles interacting with continuous core-softened intermolecular
potential. Dynamic properties are also analyzed by the simulations. We show
that, for a chosen shape of the potential, the density, at constant pressure,
has a maximum for a certain temperature. The line of temperatures of maximum
density (TMD) was determined in the pressure-temperature phase diagram.
Similarly the diffusion constant at a constant temperature, , has a maximum
at a density and a minimum at a density .
In the pressure-temperature phase-diagram the line of extrema in diffusivity is
outside of TMD line. Although in this interparticle potential lacks
directionality, this is the same behavior observed in SPC/E water.Comment: 16 page
Integração das tecnologias sociais Barraginhas e Lago de Múltiplo Uso.
A integração das tecnologias sociais barraginhas e lago de múltiplo uso vêm garantindo sustentabilidade hídrica para agricultores familiares, viabilizando criatórios de peixes e irrigação de hortas. No município de Araçaí-MG, comunidade Fazendinhas Pai José, em um solo seco sob vegetação de Cerrado, com predominância de latossolos vermelho e amarelo, porosos e profundos, após reuniões com a comunidade, foram construídas 96 barraginhas no ano de 2008 e 90 em 2009, para colher a água dos escorrimentos superficiais das chuvas: as enxurradas. Ao contê-las, foram reduzidas também as erosões e assoreamentos. As barraginhas são carregadas e descarregadas de 10 a 12 vezes por ano, infiltrando e elevando o lençol freático, umedecendo o solo em torno das mesmas e nas baixadas, amenizando secas, revitalizando córregos. Foi observado aumento do nível das cisternas de quatro para 10 a 11m de coluna de água, gerando nos agricultores sentimento de abundância. Isso viabilizou a construção de lagos impermeabilizado com lona de plástico comum para armazenamento de água durante o período seco, pelo bombeamento de água das cisternas, o que viabilizou a criação de peixes e ainda irrigação de hortas. De forma complementar, no período chuvoso, os lagos são abastecidos também por água captada por telhados. A experiência já foi reaplicada em mais dois municípios vizinhos e poderá ser extrapolada aos estados do Brasil central, onde predominam solos e condições similares
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