903 research outputs found

    Solar system constraints on Rindler acceleration

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    We discuss the classical tests of general relativity in the presence of Rindler acceleration. Among these tests the perihelion shifts give the tightest constraints and indicate that the Pioneer anomaly cannot be caused by a universal solar system Rindler acceleration. We address potential caveats for massive test-objects. Our tightest bound on Rindler acceleration that comes with no caveats is derived from radar echo delay and yields |a|<3nm/s^2.Comment: 7 pages, v2: minor changes, added references, v3: corrected typos, extended Table 1, corrected bound on measurement of gravitational redshif

    Scanning Raman spectroscopy of graphene antidot lattices: Evidence for systematic p-type doping

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    We have investigated antidot lattices, which were prepared on exfoliated graphene single layers via electron-beam lithography and ion etching, by means of scanning Raman spectroscopy. The peak positions, peak widths and intensities of the characteristic phonon modes of the carbon lattice have been studied systematically in a series of samples. In the patterned samples, we found a systematic stiffening of the G band mode, accompanied by a line narrowing, while the 2D mode energies are found to be linearly correlated with the G mode energies. We interpret this as evidence for p-type doping of the nanostructured graphene

    Linear Programming in the Semi-streaming Model with Application to the Maximum Matching Problem

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    In this paper, we study linear programming based approaches to the maximum matching problem in the semi-streaming model. The semi-streaming model has gained attention as a model for processing massive graphs as the importance of such graphs has increased. This is a model where edges are streamed-in in an adversarial order and we are allowed a space proportional to the number of vertices in a graph. In recent years, there has been several new results in this semi-streaming model. However broad techniques such as linear programming have not been adapted to this model. We present several techniques to adapt and optimize linear programming based approaches in the semi-streaming model with an application to the maximum matching problem. As a consequence, we improve (almost) all previous results on this problem, and also prove new results on interesting variants

    Nonequilibrium effects due to charge fluctuations in intrinsic Josephson systems

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    Nonequilibrium effects in layered superconductors forming a stack of intrinsic Josephson junctions are investigated. We discuss two basic nonequilibrium effects caused by charge fluctuations on the superconducting layers: a) the shift of the chemical potential of the condensate and b) charge imbalance of quasi-particles, and study their influence on IV-curves and the position of Shapiro steps.Comment: 17 pages, 2 figures, revised version slightly shortene

    Reflectivity and Microwave Absorption in Crystals with Alternating Intrinsic Josephson Junctions

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    We compute the frequency and magnetic field dependencies of the reflectivity R(ω)R(\omega) in layered superconductors with two alternating intrinsic Josephson junctions with different critical current densities and quasiparticle conductivities for the electric field polarized along the c-axis. The parameter α\alpha describing the electronic compressibility of the layers and the charge coupling of neighboring junctions was extracted for the SmLa1x_{1-x}Srx_{x}CuO4δ_{4-\delta} superconductor from two independent optical measurements, the fit of the loss function L(ω)L(\omega) at zero magnetic field and the magnetic field dependence of the peak positions in L(ω)L(\omega). The experiments are consistent with a free electron value for α\alpha near the Josephson plasma frequencies.Comment: 4 pages, 4 postscript figures, misprints in table correcte

    Real-time optical micro-manipulation using optimized holograms generated on the GPU

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    Holographic optical tweezers allow the three dimensional, dynamic, multipoint manipulation of micron sized dielectric objects. Exploiting the massive parallel architecture of modern GPUs we can generate highly optimized holograms at video frame rate allowing the interactive micro-manipulation of 3D structures.Comment: 13 pages, 8 figure

    Early Prediction of Movie Box Office Success based on Wikipedia Activity Big Data

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    Use of socially generated "big data" to access information about collective states of the minds in human societies has become a new paradigm in the emerging field of computational social science. A natural application of this would be the prediction of the society's reaction to a new product in the sense of popularity and adoption rate. However, bridging the gap between "real time monitoring" and "early predicting" remains a big challenge. Here we report on an endeavor to build a minimalistic predictive model for the financial success of movies based on collective activity data of online users. We show that the popularity of a movie can be predicted much before its release by measuring and analyzing the activity level of editors and viewers of the corresponding entry to the movie in Wikipedia, the well-known online encyclopedia.Comment: 13 pages, Including Supporting Information, 7 Figures, Download the dataset from: http://wwm.phy.bme.hu/SupplementaryDataS1.zi

    Scenicness assessment of onshore wind sites with geotagged photographs and impacts on approval and cost-efficiency

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    Funding Information: We gratefully acknowledge the contributions of D. Schlund, who carried out some of the wind analysis whilst a Student Assistant at KIT, as well as C. Moutard, on whose Master’s Thesis at DTU this article builds (Assessing the ‘acceptable’ onshore wind potential in the UK, 2019, https://findit.dtu.dk/en/catalog/2451029061). M. D’Andrea, K. Paidis and T. Jaenicke supported the preparation of early versions of the manuscript whilst Student Assistants at DTU. I.M. gratefully acknowledges financial support from Kraks Fond, Copenhagen ([email protected]). T.P. and H.S.M. are grateful for support from The Alan Turing Institute under the EPSRC grant EP/N510129/1 (including awards TU/B/000006 and TU/B/000008).Peer reviewedPostprin

    Theory for the coupling between longitudinal phonons and intrinsic Josephson oscillations in layered superconductors

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    In this publication a microscopic theory for the coupling of intrinsic Josephson oscillations in layered superconductors with longitudinal c-axis-phonons is developed. It is shown that the influence of lattice vibrations on the c-axis transport can be fully described by introducing an effective longitudinal dielectric function. Resonances in the I-V-characteristic appear at van Hove singularities of both acoustical and optical longitudinal phonon branches. This provides a natural explanation of the recently discovered subgap structures in the I-V-characteristic of highly anisotropic cuprate superconductors. The effect of the phonon dispersion on the damping of these resonances and the coupling of Josephson oscillations in different resistive junctions due to phonons are discussed in detail.Comment: submitted to Phys. Rev. B, corrections following referee repor
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