8,172 research outputs found

    FM 047-02: a collisional pair of galaxies with a ring

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    Aims. We investigate the nature of the galaxy pair FM 047-02, which has been proposed as an archetype of the Solitaire types of peculiar (collisional) ring galaxies. Methods. The study is based on long-slit spectrophotometric data in the range of 3500-9500 angstrons obtained with the Gemini Multi-ObjectComment: 07 pages, 06 figures, 02 tables. arXiv admin note: text overlap with arXiv:1206.071

    Thermographic non-destructive evaluation for natural fiber-reinforced composite laminates

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    Natural fibers, including mineral and plant fibers, are increasingly used for polymer composite materials due to their low environmental impact. In this paper, thermographic non-destructive inspection techniques were used to evaluate and characterize basalt, jute/hemp and bagasse fibers composite panels. Different defects were analyzed in terms of impact damage, delaminations and resin abnormalities. Of particular interest, homogeneous particleboards of sugarcane bagasse, a new plant fiber material, were studied. Pulsed phase thermography and principal component thermography were used as the post-processing methods. In addition, ultrasonic C-scan and continuous wave terahertz imaging were also carried out on the mineral fiber laminates for comparative purposes. Finally, an analytical comparison of different methods was give

    Grand canonical ensemble of a dd-dimensional Reissner-Nordstr\"om black hole in a cavity

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    The grand canonical ensemble of a dd-dimensional Reissner-Nordstr\"om black hole space in a cavity is analyzed. The realization of this ensemble is made through the Euclidean path integral approach by giving the Euclidean action for the black hole with the correct topology, and boundary conditions corresponding to a cavity, where the fixed quantities are the temperature and the electric potential. One performs a zero loop approximation to find and analyze the stationary points of the reduced action. This yields two solutions for the electrically charged black hole, r+1r_{+1}, which is the smaller and unstable, and r+2r_{+2}, which is the larger and stable. One also analyzes the most probable configurations, which are either a stable charged black hole or hot flat space, mimicked by a nongravitating charged shell. Making the correspondence between the action and the grand potential, one can get the black hole thermodynamic quantities, such as the entropy, the mean charge, the mean energy, and the thermodynamic pressure, as well as the Smarr formula, shown to be valid only for the unstable black hole. We find that thermodynamic stability is related to the positivity of the heat capacity at constant electric potential and area of the cavity. We also comment on the most favorable thermodynamic phases and phase transitions. We then choose d=5d = 5, which is singled out naturally from the other higher dimensions as it provides an exact solution for the problem, and apply all the results previously found. The case d=4d = 4 is mentioned. We compare thermodynamic radii with the photonic orbit radius and the Buchdahl-Andr\'easson-Wright bound radius in dd-dimensional Reissner-Nordstr\"om spacetimes and find they are unconnected, showing that the connections displayed in the Schwarzschild case are not generic, rather they are very restricted holding only in the pure gravitational situation.Comment: 28 pages, 5 figure

    Population expansion in the North African Late Pleistocene signalled by mitochondrial DNA haplogroup U6

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    Background <br/> The archaeology of North Africa remains enigmatic, with questions of population continuity versus discontinuity taking centre-stage. Debates have focused on population transitions between the bearers of the Middle Palaeolithic Aterian industry and the later Upper Palaeolithic populations of the Maghreb, as well as between the late Pleistocene and Holocene. <br/> Results Improved resolution of the mitochondrial DNA (mtDNA) haplogroup U6 phylogeny, by the screening of 39 new complete sequences, has enabled us to infer a signal of moderate population expansion using Bayesian coalescent methods. To ascertain the time for this expansion, we applied both a mutation rate accounting for purifying selection and one with an internal calibration based on four approximate archaeological dates: the settlement of the Canary Islands, the settlement of Sardinia and its internal population re-expansion, and the split between haplogroups U5 and U6 around the time of the first modern human settlement of the Near East. <br/> Conclusions <br/> A Bayesian skyline plot placed the main expansion in the time frame of the Late Pleistocene, around 20 ka, and spatial smoothing techniques suggested that the most probable geographic region for this demographic event was to the west of North Africa. A comparison with U6's European sister clade, U5, revealed a stronger population expansion at around this time in Europe. Also in contrast with U5, a weak signal of a recent population expansion in the last 5,000 years was observed in North Africa, pointing to a moderate impact of the late Neolithic on the local population size of the southern Mediterranean coast

    The individuals' discretionary behaviors at work. An overview and analysis of its growing interest

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    Nearly forty years have passed since the term Organizational Citizenship Behavior appeared. Despite a current consensus among scholars about the citizenship gestures as prosocial acts of employees that benefit the organization, it does not apply commonly to the exponential growth of all OCB-related concepts. The concept's expansion has confused the researchers and practitioners, mainly when choosing the most appropriate instruments (constructs) and dimensions to use in their area of interest and context. A systematic literature review was conducted and 420 articles were analyzed. Results point that the trends on OCB-like behaviors goes higher, with an average annual growth rate of new studies of 3.13%. United States (39%) and China (25%) lead but some "under-studied" contexts like Africa, Latin America, the Caribbean, and Oceania start being studied towards OCB. New trends appear in the spectrum of the many different domains and disciplines related to OCB, while leadership and task performance remain the most studied domains and disciplines. In future studies, researchers must freely choose the OCB dimensions and constructs they want to use or adapt to meet their needs and research needs since there is no written rule about their use, only the care to be taken with the context and discipline studying.info:eu-repo/semantics/publishedVersio

    Cadastro das amassadeiras de açaí de Macapá, estado do Amapá.

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    As características selecionadas dos pontos de venda de vinho de açaí, denominadas de amassadeiras, foram pesquisadas na cidade de Macapá, em agosto e setembro de 2002, e algumas delas são representadas no presente documento. Nome do proprietário/entrevistado, nome fantasia, endereço, bairro, relação de propriedade, tempo de atividade no ponto, tempo de atividade como beneficiador e mão-de-obra ocupada são os aspectos privilegiados.bitstream/item/95892/1/CPAF-AP-2003-Cadastro-amassadeiras.pd
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