1,500 research outputs found

    On explicit results at the intersection of the Z_2 and Z_4 orbifold subvarieties in K3 moduli space

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    We examine the recently found point of intersection between the Z_2 and Z_4 orbifold subvarieties in the K3 moduli space more closely. First we give an explicit identification of the coordinates of the respective Z_2 and Z_4 orbifold theories at this point. Secondly we construct the explicit identification of conformal field theories at this point and show the orthogonality of the two subvarieties.Comment: Latex, 23 page

    Handling of missing values in statistical software packages for windows

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    The problem of estimating parameters of distributions by an incomplete data set is theoretically considered, but in practice the implementation of the developed methods in commercial statistical software packages varies from program to program. None of the examined software offers all possible methods. In some programs the user has no choice concerning the use of a method, or no methods at all are available. However, the most popular programs have not always the largest variety of methods. Hence some work is still waiting for the producer of statistical software

    Laser Doppler velocimeter aerial spray measurements

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    An experimental research program for measuring the location, spatial extent, and relative concentration of airborne spray clouds generated by agricultural aircraft is described. The measurements were conducted with a ground-based laser Doppler velocimeter. The remote sensing instrumentation, experimental tests, and the results of the flight tests are discussed. The cross section of the aerial spray cloud and the observed location, extent, and relative concentration of the airborne particulates are presented. It is feasible to use a mobile laser Doppler velocimeter to track and monitor the transport and dispersion of aerial spray generated by an agricultural aircraft

    Physical Electronics and Surface Physics

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    Contains research objectives and reports on four research projects.National Aeronautics and Space Administration (Grant NGR-22-009-091)M. I. T. Cabot Solar Energy FundJoint Services Electronics Programs (U. S. Army, U.S. Navy, and U.S. Air Force) under Contract DA 36-039-AMC-03200(E

    Pattern Formation in Semiconductors

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    In semiconductors, nonlinear generation and recombination processes of free carriers and nonlinear charge transport can give rise to non-equilibrium phase transitions. At low temperatures, the basic nonlinearity is due to the autocatalytic generation of free carriers by impact ionization of shallow impurities. The electric field accelerates free electrons, causing an abrupt increase in free carrier density at a critical electric field. In static electric fields, this nonlinearity is known to yield complex filamentary current patterns bound to electric contacts

    Quantum Enhancement of the Zero-Area Sagnac Interferometer Topology for Gravitational Wave Detection

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    Only a few years ago, it was realized that the zero-area Sagnac interferometer topology is able to perform quantum nondemolition measurements of position changes of a mechanical oscillator. Here, we experimentally show that such an interferometer can also be efficiently enhanced by squeezed light. We achieved a nonclassical sensitivity improvement of up to 8.2 dB, limited by optical loss inside our interferometer. Measurements performed directly on our squeezed-light laser output revealed squeezing of 12.7 dB. We show that the sensitivity of a squeezed-light enhanced Sagnac interferometer can surpass the standard quantum limit for a broad spectrum of signal frequencies without the need for filter cavities as required for Michelson interferometers. The Sagnac topology is therefore a powerful option for future gravitational-wave detectors, such as the Einstein Telescope, whose design is currently being studied.Comment: 4 pages, 4 figure

    Melanoma of the middle ear: initial presentation, Fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography imaging and follow up

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    Abstract Background: We present a rare case of primary mucosal melanoma of the middle ear imaged with 18F-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography (FDG-PET/CT). Method: Clinical, radiological, intra-operative and histological findings are discussed. Results: An 88-year-old woman presented with intermittent otorrhoea of the left ear for several months. Otoscopy revealed a livid protrusion of the tympanic membrane. Melanoma was not suspected initially, but was established on transmembranous biopsy. Pre-operative 18F-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography revealed a mass lesion in the left tympanic cavity with high fluoro-deoxyglucose uptake, as well as an ipsilateral intraparotid lymph node metastasis. The patient underwent surgical treatment. The diagnosis of melanoma was confirmed histologically. Conclusion: In this rare case, clinical, radiological and surgical findings led to the diagnosis of a primary mucosal melanoma of the middle ea

    Twistfield Perturbations of Vertex Operators in the Z_2-Orbifold Model

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    We apply Kadanoff's theory of marginal deformations of conformal field theories to twistfield deformations of Z_2 orbifold models in K3 moduli space. These deformations lead away from the Z_2 orbifold sub-moduli-space and hence help to explore conformal field theories which have not yet been understood. In particular, we calculate the deformation of the conformal dimensions of vertex operators for p^2<1 in second order perturbation theory.Comment: Latex2e, 19 pages, 1 figur
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