2,085 research outputs found

    Initial Data and Coordinates for Multiple Black Hole Systems

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    We present here an alternative approach to data setting for spacetimes with multiple moving black holes generalizing the Kerr-Schild form for rotating or non-rotating single black holes to multiple moving holes. Because this scheme preserves the Kerr-Schild form near the holes, it selects out the behaviour of null rays near the holes, may simplify horizon tracking, and may prove useful in computational applications. For computational evolution, a discussion of coordinates (lapse function and shift vector) is given which preserves some of the properties of the single-hole Kerr-Schild form

    Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) in association with an adenocarcinoma: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is a rare disorder and information on this disease is limited, especially with regard to its management and prognosis. It has become generally accepted that DIPNECH is a precursor lesion to pulmonary carcinoid tumors.</p> <p>Case presentation</p> <p>Here we report on a 60-year-old female patient with DIPNECH and an associated pulmonary adenocarcinoma.</p> <p>Conclusion</p> <p>This case contributes to a better understanding of the disorder and its associated pathologies.</p

    Some remarks on a new exotic spacetime for time travel by free fall

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    This work is essentially a review of a new spacetime model with closed causal curves, recently presented in another paper (Class. Quantum Grav. \textbf{35}(16) (2018), 165003). The spacetime at issue is topologically trivial, free of curvature singularities, and even time and space orientable. Besides summarizing previous results on causal geodesics, tidal accelerations and violations of the energy conditions, here redshift/blueshift effects and the Hawking-Ellis classification of the stress-energy tensor are examined.Comment: 17 pages, 9 figures. Submitted as a contribution to the proceedings of "DOMOSCHOOL - International Alpine School of Mathematics and Physics, Domodossola 2018". Possible text overlaps with my previous work arXiv:1803.08214, of which this is essentially a review. Additional results concerning redshift/blueshift effects and the classification of the stress-energy tensor are presented her

    Black Hole Data via a Kerr-Schild Approach

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    We present a new approach for setting initial Cauchy data for multiple black hole spacetimes. The method is based upon adopting an initially Kerr-Schild form of the metric. In the case of non-spinning holes, the constraint equations take a simple hierarchical form which is amenable to direct numerical integration. The feasibility of this approach is demonstrated by solving analytically the problem of initial data in a perturbed Schwarzschild geometry.Comment: 13 pages, RevTeX forma

    Microwave Gaseous Discharges

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    Contains reports on three research projects
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