24,179 research outputs found

    Quantum Evolution of Inhomogeneities in Curved Space

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    We obtain the renormalized equations of motion for matter and semi-classical gravity in an inhomogeneous space-time. We use the functional Schrodinger picture and a simple Gaussian approximation to analyze the time evolution of the λϕ4\lambda\phi^4 model, and we establish the renormalizability of this non-perturbative approximation. We also show that the energy-momentum tensor in this approximation is finite once we consider the usual mass and coupling constant renormalizations, without the need of further geometrical counter-terms.Comment: 22 page

    Literacy: A cultural influence on functional left-right differences in the inferior parietal cortex

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    The current understanding of hemispheric interaction is limited. Functional hemispheric specialization is likely to depend on both genetic and environmental factors. In the present study we investigated the importance of one factor, literacy, for the functional lateralization in the inferior parietal cortex in two independent samples of literate and illiterate subjects. The results show that the illiterate group are consistently more right-lateralized than their literate controls. In contrast, the two groups showed a similar degree of left-right differences in early speech-related regions of the superior temporal cortex. These results provide evidence suggesting that a cultural factor, literacy, influences the functional hemispheric balance in reading and verbal working memory-related regions. In a third sample, we investigated grey and white matter with voxel-based morphometry. The results showed differences between literacy groups in white matter intensities related to the mid-body region of the corpus callosum and the inferior parietal and parietotemporal regions (literate > illiterate). There were no corresponding differences in the grey matter. This suggests that the influence of literacy on brain structure related to reading and verbal working memory is affecting large-scale brain connectivity more than grey matter per se

    Biodegradable polymeric fiber structures in tissue engineering

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    Tissue engineering offers a promising new approach to create biological alternatives to repair or restore function of damaged or diseased tissues. To obtain three-dimensional tissue constructs, stem or progenitor cells must be combined with a highly porous three-dimensional scaffold, but many of the structures purposed for tissue engineering cannot meet all the criteria required by an adequate scaffold because of lack of mechanical strength and interconnectivity, as well as poor surface characteristics. Fiber-based structures represent a wide range of morphological and geometric possibilities that can be tailored for each specific tissue-engineering application. The present article overviews the research data on tissue-engineering therapies based on the use of biodegradable fiber architectures as a scaffold

    Building an Organization to Last: Reflections and Lessons Learned From SeaChange

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    Shares an important case study of best practices of grantmaking and organizational effectiveness. Contains lessons about leadership, governance, management and accountability

    e-Philanthropy v2.001: From Entrepreneurial Adventure to an Online Community

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    Looks at interactive online services for philanthropy and volunteerism. Identifies, describes and anticipates the changing and maturing structure of Internet-facilitated information and services that support the various dimensions of the social sector

    Periodic Anderson model with electron-phonon correlated conduction band

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    This paper reports dynamical mean field calculations for the periodic Anderson model in which the conduction band is coupled to phonons. Motivated in part by recent attention to the role of phonons in the γ\gamma-α\alpha transition in Ce, this model yields a rich and unexpected phase diagram which is of intrinsic interest. Specifically, above a critical value of the electron-phonon interaction, a first order transition with two coexisting phases develops in the temperature-hybridization plane, which terminates at a second order critical point. The coexisting phases display the familiar Kondo screened and local moment character, yet they also exhibit pronounced polaronic and bipolaronic properties, respectively.Comment: 4 pages, 6 figure
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