38,305 research outputs found

    Evaluations of k-fold Euler/Zagier sums: a compendium of results for arbitrary k

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    Euler sums (also called Zagier sums) occur within the context of knot theory and quantum field theory. There are various conjectures related to these sums whose incompletion is a sign that both the mathematics and physics communities do not yet completely understand the field. Here, we assemble results for Euler/Zagier sums (also known as multidimensional zeta/harmonic sums) of arbitrary depth, including sign alternations. Many of our results were obtained empirically and are apparently new. By carefully compiling and examining a huge data base of high precision numerical evaluations, we can claim with some confidence that certain classes of results are exhaustive. While many proofs are lacking, we have sketched derivations of all results that have so far been proved.Comment: 19 pages, LaTe

    Tripartite entanglement from interlinked χ(2)\chi^{(2)} parametric interactions

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    We examine the tripartite entanglement properties of an optical system using interlinked χ(2)\chi^{(2)} interactions, recently studied experimentally in terms of its phase-matching properties by Bondani et al [M. Bondani, A. Allevi, E. Gevinti, A. Agliati, and A. Andreoni, arXiv:quant-ph/0604002.]. We show that the system does produce output modes which are genuinely tripartite entangled and that detection of this entanglement depends crucially on the correlation functions which are measured, with a three-mode Einstein-Podolsky-Rosen inequality being the most sensitive.Comment: 15 pages, 5 figure

    Scientific publications and presentations relating to planetary quarantine. Volume 5: The 1972 supplement

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    The sixth annual supplement to the bibliography on planetary quarantine contains 191 references, an author index and a permuted title index

    Axistationary perfect fluids -- a tetrad approach

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    Stationary axisymmetric perfect fluid space-times are investigated using the curvature description of geometries. Attention is focused on space-times with a vanishing electric part of the Weyl tensor. It is shown that the only incompressible axistationary magnetic perfect fluid is the interior Schwarzschild solution. The existence of a rigidly rotating perfect fluid, generalizing the interior Schwarzschild metric is proven. Theorems are stated on Petrov types and electric/magnetic Weyl tensors.Comment: 12 page

    How Well Does "Core" CPI Capture Permanent Price Changes?

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    We decompose core CPI and the food and energy CPI measures into permanent and transitory components using a correlated unobserved components model, to examine the behavior of core CPI when subject to shocks and to examine the claim that core CPI captures the persistent part of headline CPI. We find that the permanent component of core CPI is more volatile than core CPI, or that the permanent and transitory components are highly correlated. We find that the excluded food and energy components have important permanent components, and that core CPI has an important transitory component. We examine impulse response functions and find that headline CPI inflation responds more sharply to shocks than core CPI inflation, and after the first year the impact of shocks on headline inflation is less than the impact on core inflation.unobserved components, CPI, price indices, inflation, core
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