25,963 research outputs found

    Naturalizing the Female Body: Social Control through Reproduction

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    Objective: To discuss alternatives to understand how the medical sciences have reduced the female body conceptually to its biological dimension as the foundation for its social control

    Spectral and Fermi surface properties from Wannier interpolation

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    We present an efficient first-principles approach for calculating Fermi surface averages and spectral properties of solids, and use it to compute the low-field Hall coefficient of several cubic metals and the magnetic circular dichroism of iron. The first step is to perform a conventional first-principles calculation and store the low-lying Bloch functions evaluated on a uniform grid of k-points in the Brillouin zone. We then map those states onto a set of maximally-localized Wannier functions, and evaluate the matrix elements of the Hamiltonian and the other needed operators between the Wannier orbitals, thus setting up an ``exact tight-binding model.'' In this compact representation the k-space quantities are evaluated inexpensively using a generalized Slater-Koster interpolation. Because of the strong localization of the Wannier orbitals in real space, the smoothness and accuracy of the k-space interpolation increases rapidly with the number of grid points originally used to construct the Wannier functions. This allows k-space integrals to be performed with ab-initio accuracy at low cost. In the Wannier representation, band gradients, effective masses, and other k-derivatives needed for transport and optical coefficients can be evaluated analytically, producing numerically stable results even at band crossings and near weak avoided crossings.Comment: 12 pages, 7 figure

    How does early defoliation influence the morphophysiology and biochemical characteristics of maize?

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    Defoliation is a type of mechanical stress, and few studies have investigated this process in the early stages of maize development. Pest attacks, hail and machinery traffic have increased in recent decades, thus increasing this stress and potentially leading to losses. Furthermore, there are corn production systems in Brazil where early defoliation naturally occurs. Thus, the objective of this study was to determine the morphophysiological and biochemical changes in maize subjected to early defoliation and their effects on recovery from this stress. The experiment was performed in pots, and the plants were subjected to two treatments at the four fully expanded leaf stage: without defoliation (control) and with defoliation. Morphometric parameters, such as gas exchange, leaf pigment and biomolecule content, phytohormone con- tent, root morphology and leaf anatomy, were evaluated at seven and fourteen days after defoliation. Compared with the control plants, the defoliated corn plants were shorter in height, stem diameter, length, surface area, root diameter and volume, dry biomass and leaf anatomy. However, photosynthesis, chlorophyll content and nutrient content were similar in both treatments. After seven days of treatment, the amino acid content increased in the defoliated plants, and after fourteen days, the reducing sugars, amino acids and proteins decreased in these plants. The levels of gibberellins and salicylic acid were greater in plants subjected to defoliation. The reestablishment of corn plants after defoliation occurred through the action of gibberellins and salicylic acid, which promoted the growth of aboveground biomass, maintenance of chlorophylls and gas exchange. The reallocation of amino acids and reducing sugars also contributes to the formation of new leaf primordia in defoliated plants

    VLTI/PIONIER images the Achernar disk swell

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    Context. The mechanism of disk formation around fast-rotating Be stars is not well understood. In particular, it is not clear which mechanisms operate, in addition to fast rotation, to produce the observed variable ejection of matter. The star Achernar is a privileged laboratory to probe these additional mechanisms because it is close, presents B-Be phase variations on timescales ranging from 6 yr to 15 yr, a companion star was discovered around it, and probably presents a polar wind or jet. Aims. Despite all these previous studies, the disk around Achernar was never directly imaged. Therefore we seek to produce an image of the photosphere and close environment of the star. Methods. We used infrared long-baseline interferometry with the PIONIER/VLTI instrument to produce reconstructed images of the photosphere and close environment of the star over four years of observations. To study the disk formation, we compared the observations and reconstructed images to previously computed models of both the stellar photosphere alone (normal B phase) and the star presenting a circumstellar disk (Be phase). Results. The observations taken in 2011 and 2012, during the quiescent phase of Achernar, do not exhibit a disk at the detection limit of the instrument. In 2014, on the other hand, a disk was already formed and our reconstructed image reveals an extended H-band continuum excess flux. Our results from interferometric imaging are also supported by several H-alpha line profiles showing that Achernar started an emission-line phase sometime in the beginning of 2013. The analysis of our reconstructed images shows that the 2014 near-IR flux extends to 1.7 - 2.3 equatorial radii. Our model-independent size estimation of the H-band continuum contribution is compatible with the presence of a circumstellar disk, which is in good agreement with predictions from Be-disk models

    Reference Models for Production Planning and Control Systems: A Bibliometric Analysis and Future Perspectives

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    The activity of modeling business processes is still not a common practice among organizations which contributes to increase the cost and time of systems deployment, improvement projects and educational software, due to the need to develop new models related to Business Processes. In this context, one of the Business Processes essential for organizations, especially those located in countries such as Brazil, where production activities are more pronounced than product development, is Production Planning and Control (PCP). In this scenario, in order to present a picture of scientific production, contribute to the literature review and identify gaps in the scientific literature within the framework of the Reference Models and PCP approach. This work aims to perform a bibliometric research in these areas of study. In this study, we used the bibliometric revision method composed of four phases: definition of database, definition of research keywords, selection of papers and analysis of papers. As a result, it was found that most scientific studies are focused on very specific situations in industrial planning or addressing particular business sectors
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