56 research outputs found

    Thermo-elasticity for anisotropic media in higher dimensions

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    In this note we develop tools to study the Cauchy problem for the system of thermo-elasticity in higher dimensions. The theory is developed for general homogeneous anisotropic media under non-degeneracy conditions. For degenerate cases a method of treatment is sketched and for the cases of cubic media and hexagonal media detailed studies are provided.Comment: 33 pages, 5 figure

    The wave front set of oscillatory integrals with inhomogeneous phase function

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    A generalized notion of oscillatory integrals that allows for inhomogeneous phase functions of arbitrary positive order is introduced. The wave front set of the resulting distributions is characterized in a way that generalizes the well-known result for phase functions that are homogeneous of order one.Comment: 12 pages, published versio

    Trace ideals for Fourier integral operators with non-smooth symbols II

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    We consider Fourier integral operators with symbols in modulation spaces and non-smooth phase functions whose second orders of derivatives belong to certain types of modulation space. We establish continuity and Schatten-von Neumann properties of such operators when acting on modulation spaces.Comment: 25 page

    Structural resolvent estimates and derivative nonlinear Schrodinger equations

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    A refinement of uniform resolvent estimate is given and several smoothing estimates for Schrodinger equations in the critical case are induced from it. The relation between this resolvent estimate and radiation condition is discussed. As an application of critical smoothing estimates, we show a global existence results for derivative nonlinear Schrodinger equations.Comment: 21 page

    The global wave front set of tempered oscillatory integrals with inhomogeneous phase functions

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    We study certain families of oscillatory integrals Iφ(a)I_\varphi(a), parametrised by phase functions φ\varphi and amplitude functions aa globally defined on Rd\mathbb{R}^d, which give rise to tempered distributions, avoiding the standard homogeneity requirement on the phase function. The singularities of Iφ(a)I_\varphi(a) are described both from the point of view of the lack of smoothness as well as with respect to the decay at infinity. In particular, the latter will depend on a version of the set of stationary points of φ\varphi, including elements lying at the boundary of the radial compactification of Rd\mathbb{R}^d. As applications, we consider some properties of the two-point function of a free, massive, scalar relativistic field and of classes of global Fourier integral operators on Rd\mathbb{R}^d, with the latter defined in terms of kernels of the form Iφ(a)I_\varphi(a).Comment: 30 pages, 2 figures, mistakes and typos correctio

    Approximation of Fourier Integral Operators by Gabor multipliers

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    A general principle says that the matrix of a Fourier integral operator with respect to wave packets is concentrated near the curve of propagation. We prove a precise version of this principle for Fourier integral operators with a smooth phase and a symbol in the Sjoestrand class and use Gabor frames as wave packets. The almost diagonalization of such Fourier integral operators suggests a specific approximation by (a sum of) elementary operators, namely modified Gabor multipliers. We derive error estimates for such approximations. The methods are taken from time-frequency analysis.Comment: 22. page

    Assessing mNIS+7Ionis and international neurologists' proficiency in a familial amyloidotic polyneuropathy trial

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    INTRODUCTION: Polyneuropathy signs (Neuropathy Impairment Score, NIS), neurophysiologic tests (m+7Ionis ), disability, and health scores were assessed in baseline evaluations of 100 patients entered into an oligonucleotide familial amyloidotic polyneuropathy (FAP) trial. METHODS: We assessed: (1) Proficiency of grading neurologic signs and correlation with neurophysiologic tests, and (2) clinometric performance of modified NIS+7 neurophysiologic tests (mNIS+7Ionis ) and its subscores and correlation with disability and health scores. RESULTS: The mNIS+7Ionis sensitively detected, characterized, and broadly scaled diverse polyneuropathy impairments. Polyneuropathy signs (NIS and subscores) correlated with neurophysiology tests, disability, and health scores. Smart Somatotopic Quantitative Sensation Testing of heat as pain 5 provided a needed measure of small fiber involvement not adequately assessed by other tests. CONCLUSIONS: Specially trained neurologists accurately assessed neuropathy signs as compared to referenced neurophysiologic tests. The score, mNIS+7Ionis , broadly detected, characterized, and scaled polyneuropathy abnormality in FAP, which correlated with disability and health scores. Muscle Nerve 56: 901-911, 2017

    On global inversion of homogeneous maps

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    Unlocking Thesis Data phase one

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    Unlocking Thesis Data (UTD) is a community-driven project to promote the use of persistent identifiers for theses, their underlying data and their authors. By their very nature, PhD theses break new ground and advance scholarly knowledge. Most make use of newly-created data but these data can be trapped in an appendix or DVD – either unavailable or not suited for reuse. UTD will make data more discoverable and citeable, thereby offering incentives to students to share their data in more appropriate formats, in the context of a sustainable national thesis framework. Funded by Jisc, UTD is led by the Universities of East London and Southampton and EThOS (the UK’s national thesis service at the British Library). Phase one will explore current thesis practice through an online survey to EThOS member institutions, and individual case studies looking at the issues in more detail – including how institutions might apply DOI and ORCID identifiers. The survey and case study findings will be combined into a report with recommendations for further phases of the project. These are expected to enhance metadata and software for applying DOI and ORCID identifiers, to test them in live settings, and to offer comprehensive advice for institutions to adopt them. By summer 2016 we expect to have a sustainable infrastructure covering the whole UK, driving the wider availability of research data and introducing doctoral students to new norms of scholarly communication
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