466 research outputs found

    Comparative quantitative analysis reveals preserved structural connectivity patterns in the human and macaque brain

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    The macaque brain serves as a model for the human brain, but its suitability is challenged by unique human features, including connectivity reconfigurations, which emerged during primate evolution. We perform a quantitative comparative analysis of the whole brain macroscale structural connectivity of the two species. Our findings suggest that the human and macaque brain as a whole are similarly wired. A region-wise analysis reveals many interspecies similarities of connectivity patterns, but also lack thereof, primarily involving cingulate and parietal regions. We unravel a common structural backbone in both species involving a highly overlapping set of regions. This structural backbone, important for mediating information across the brain, constitutes a feature of the primate brain persevering evolution. Our findings illustrate novel evolutionary aspects at the macroscale connectivity level, including the existence of common topological structures, and offer a quantitative translational bridge between macaque and human research

    Shape analysis on homogeneous spaces: a generalised SRVT framework

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    Shape analysis is ubiquitous in problems of pattern and object recognition and has developed considerably in the last decade. The use of shapes is natural in applications where one wants to compare curves independently of their parametrisation. One computationally efficient approach to shape analysis is based on the Square Root Velocity Transform (SRVT). In this paper we propose a generalised SRVT framework for shapes on homogeneous manifolds. The method opens up for a variety of possibilities based on different choices of Lie group action and giving rise to different Riemannian metrics.Comment: 28 pages; 4 figures, 30 subfigures; notes for proceedings of the Abel Symposium 2016: "Computation and Combinatorics in Dynamics, Stochastics and Control". v3: amended the text to improve readability and clarify some points; updated and added some references; added pseudocode for the dynamic programming algorithm used. The main results remain unchange

    Femtosecond Laser-Produced Plasma X-Rays from Periodically Modulated Surface Targets

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    We have studied theoretically and experimentally the x-ray production above 1 keV from femtosecond laser plasmas generated on periodically modulated surface targets. Laser energy coupling to plasma surface waves has been modeled using a numerical differential method. Almost total absorption of incident laser radiation is predicted for optimized interaction conditions. Silicon gratings have been irradiated by a 120fs Ti:sapphire laser at irradiances in excess of 1016 W/cm2. X-ray intensities above 1.5 keV (K-shell lines) have been measured as a function of the incidence angle. Results show a distinct x-ray emission maximum for the first order diffraction angle and are in good qualitative agreement with our theoretical predictions

    Dyslexia-friendly schools and parent partnership: inclusion and home-school relationships

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    This is a postprint of an article whose final and definitive form has been published in the European Journal of Special Needs Education© 2005 Copyright Taylor & Francis; European Journal of Special Needs Education is available online at http://www.informaworld.comThis paper summarizes an action research project in five local areas in the south-west of England which aimed to support parents of children with dyslexic difficulties who were experiencing problems in obtaining appropriate provision in mainstream schools. It was based on the importance of effective parental partnership and quality inclusive practice for children having dyslexic difficulties. A development officer worked over two years in the five participating LEAs that were selected to represent a range of professional practice with a mix of urban and rural populations. As part of the evaluation, the authors also examined longitudinally the educational experiences of a sample of parents. The paper includes a conceptual framework of parental agency in this field in terms of knowledge, identity and parental strategies, and the conditions under which parents escalate their strategies to secure appropriate provision for their children. The support provided by the development officer is analysed in terms of the kinds of support requests received, the kinds of support offered and qualitative evidence of the impact of this support. This research is theorized in terms of current ideas about parent-partnership and theories about parent-teacher relations in terms of the diversity of parents. It highlights the significance of thinking about inclusive schooling and parent-school relations in terms of the interconnections between general systems for all, for those with special educational needs and those with specific difficulties. The policy and practice implications are interpreted in terms of the importance of a system of extended professionalism, which is inclusive of parents with learning difficulties and disabilities.The research project this paper summarises was funded by the British Dyslexia Association (BDA) and the Buttle Trust

    Iron and Nickel spectral opacity calculations in conditions relevant for pulsating stellar envelopes and experiments

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    Seismology of stars is strongly developing. To address this question we have formed an international collaboration OPAC to perform specific experimental measurements, compare opacity calculations and improve the opacity calculations in the stellar codes [1]. We consider the following opacity codes: SCO, CASSANDRA, STA, OPAS, LEDCOP, OP, SCO-RCG. Their comparison has shown large differences for Fe and Ni in equivalent conditions of envelopes of type II supernova precursors, temperatures between 15 and 40 eV and densities of a few mg/cm3 [2, 3, 4]. LEDCOP, OPAS, SCO-RCG structure codes and STA give similar results and differ from OP ones for the lower temperatures and for spectral interval values [3]. In this work we discuss the role of Configuration Interaction (CI) and the influence of the number of used configurations. We present and include in the opacity code comparisons new HULLAC-v9 calculations [5, 6] that include full CI. To illustrate the importance of this effect we compare different CI approximations (modes) available in HULLAC-v9 [7]. These results are compared to previous predictions and to experimental data. Differences with OP results are discussed.Comment: 4 pages, 3 figures, conference Inertial Fusion Sciences and Applications, Bordeaux, 12th to 16th September 2011; EPJ web of Conferences 201

    WormBase 2007

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    WormBase (www.wormbase.org) is the major publicly available database of information about Caenorhabditis elegans, an important system for basic biological and biomedical research. Derived from the initial ACeDB database of C. elegans genetic and sequence information, WormBase now includes the genomic, anatomical and functional information about C. elegans, other Caenorhabditis species and other nematodes. As such, it is a crucial resource not only for C. elegans biologists but the larger biomedical and bioinformatics communities. Coverage of core areas of C. elegans biology will allow the biomedical community to make full use of the results of intensive molecular genetic analysis and functional genomic studies of this organism. Improved search and display tools, wider cross-species comparisons and extended ontologies are some of the features that will help scientists extend their research and take advantage of other nematode species genome sequences

    Role of surface roughness in hard x-ray emission from femtosecond laser produced copper plasmas

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    The hard x-ray emission in the energy range of 30-300 keV from copper plasmas produced by 100 fs, 806 nm laser pulses at intensities in the range of 1015−1016^{15}-10^{16} W cm−2^{-2} is investigated. We demonstrate that surface roughness of the targets overrides the role of polarization state in the coupling of light to the plasma. We further show that surface roughness has a significant role in enhancing the x-ray emission in the above mentioned energy range.Comment: 5 pages, 4 figures, to appear in Phys. Rev.
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