15,425 research outputs found

    Optimal Summation and Integration by Deterministic, Randomized, and Quantum Algorithms

    Get PDF
    We survey old and new results about optimal algorithms for summation of finite sequences and for integration of functions from Hoelder or Sobolev spaces. First we discuss optimal deterministic and randomized algorithms. Then we add a new aspect, which has not been covered before on conferences about (quasi-) Monte Carlo methods: quantum computation. We give a short introduction into this setting and present recent results of the authors on optimal quantum algorithms for summation and integration. We discuss comparisons between the three settings. The most interesting case for Monte Carlo and quantum integration is that of moderate smoothness k and large dimension d which, in fact, occurs in a number of important applied problems. In that case the deterministic exponent is negligible, so the n^{-1/2} Monte Carlo and the n^{-1} quantum speedup essentially constitute the entire convergence rate. We observe that -- there is an exponential speed-up of quantum algorithms over deterministic (classical) algorithms, if k/d tends to zero; -- there is a (roughly) quadratic speed-up of quantum algorithms over randomized classical algorithms, if k/d is small.Comment: 13 pages, contribution to the 4th International Conference on Monte Carlo and Quasi-Monte Carlo Methods, Hong Kong 200

    The National Wealth of Selected Countries - A Descriptive Essay

    Get PDF
    What determines the wealth of nations? If anyone knew the answer to that question, no-one would have heard of Adam Smith as an economist, and for that matter all economists. Economics is really the study of wealth creation under scarcity. The reason economists and others have a hard time pinning down the causes of wealth is that wealth is costly to measure, and many factors and forces are potential determinants. This paper describes, in a simple way, wealth accounting by extending the data assembled by a recent World Bank study. The extension will benefit those seeking to run time-series, cross-section, and/or pooled data regressions to assess how wealth is determined. But even from this simple data mining exercise alone the results indicate significant increases in the wealth of the 92 countries in this sample. From the theoretical standpoint the World Bank’s expanded measure under-estimates the wealth of developing countries. Yet, even if the income (GDP) component of their wealth has fallen, total national wealth has increased. The policy implications of this essay are tentative until empirical analysis is carried; even so, the results seem to suggest that GDP is a necessary but not a sufficient requirement for wealth.national wealth; Alfred Marshall on wealth, estimating wealth, World Bank’s national wealth estimating

    Exchange coupling between magnetic layers across non-magnetic superlattices

    Full text link
    The oscillation periods of the interlayer exchange coupling are investigated when two magnetic layers are separated by a metallic superlattice of two distinct non-magnetic materials. In spite of the conventional behaviour of the coupling as a function of the spacer thickness, new periods arise when the coupling is looked upon as a function of the number of cells of the superlattice. The new periodicity results from the deformation of the corresponding Fermi surface, which is explicitly related to a few controllable parameters, allowing the oscillation periods to be tuned.Comment: 13 pages; 5 figures; To appear in J. Phys.: Cond. Matte

    NNLO predictions for Z-boson pair production at the LHC

    Full text link
    We present a calculation of the NNLO QCD corrections to Z-boson pair production at hadron colliders, based on the N-jettiness method for the real radiation parts. We discuss the size and shape of the perturbative corrections along with their associated scale uncertainties and compare our results to recent LHC data at s=13\sqrt{s}=13 TeV.Comment: 19 pages, 2 Tables, 4 figures. Version to appear in JHE

    A discrete particle simulation study on the influence of restitution coefficient on spout fluidized bed dynamics

    Get PDF
    In this paper the influence of the normal restitution coefficient on the bed dynamics\ud during different flow regimes was studied using the discrete element model. The three flow\ud regimes comprise the intermediate/spout-fluidization, spouting-with-aeration regime and the jetin-\ud fluidized-bed. It is shown that with increase of the restitution coefficient the average bed\ud height decreases for all flow regime cases. To study the influence of the granule impact velocity\ud and the liquid film on the wall surface the free-fall experiments in the velocity range of 0.5-\ud 4.5 m/s were performed with spherical γ-Al2O3 granules. During the free-fall tests, the impact\ud angle from 0° to 80° and the viscosity of thin liquid film in the range of 1-300 mPa·s were\ud varied

    The anomeric specificity of yeast galactokinase

    Get PDF
    Anomeric specificity of yeast galactokinase by chromatographic method

    Numerical evaluation of two-loop integrals with pySecDec

    Full text link
    We describe the program pySecDec, which factorises endpoint singularities from multi-dimensional parameter integrals and can serve to calculate integrals occurring in higher order perturbative calculations numerically. We focus on the new features and on frequently asked questions about the usage of the program.Comment: 11 pages, to appear in the proceedings of the HiggsTools Final Meeting, IPPP, University of Durham, UK, September 201
    corecore