1,300 research outputs found

    Nonvolatile read/write memory element - A concept

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    Memory, with limited number of programming cycles, is achieved by using verticle, fusible links in series with oxide breakthrough elements. Memory elements are fabricated with integrated circuit technology and are ideal for low power digital computer application

    B-meson decay constants: a more complete picture from full lattice QCD

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    We extend the picture of BB-meson decay constants obtained in lattice QCD beyond those of the BB, BsB_s and BcB_c to give the first full lattice QCD results for the B∗B^*, Bs∗B^*_s and Bc∗B^*_c. We use improved NonRelativistic QCD for the valence bb quark and the Highly Improved Staggered Quark (HISQ) action for the lighter quarks on gluon field configurations that include the effect of u/du/d, ss and cc quarks in the sea with u/du/d quark masses going down to physical values. For the ratio of vector to pseudoscalar decay constants, we find fB∗/fBf_{B^*}/f_B = 0.941(26), fBs∗/fBsf_{B^*_s}/f_{B_s} = 0.953(23) (both 2σ2\sigma less than 1.0) and fBc∗/fBcf_{B^*_c}/f_{B_c} = 0.988(27). Taking correlated uncertainties into account we see clear indications that the ratio increases as the mass of the lighter quark increases. We compare our results to those using the HISQ formalism for all quarks and find good agreement both on decay constant values when the heaviest quark is a bb and on the dependence on the mass of the heaviest quark in the region of the bb. Finally, we give an overview plot of decay constants for gold-plated mesons, the most complete picture of these hadronic parameters to date.Comment: 20 pages, 9 figures. Minor updates to the discussion in several places and some additional reference

    Determining the natural frequencies of spheroids via the boundary-value problem formulation

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    Opening the Rome-Southampton window for operator mixing matrices

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    We show that the running of operators which mix under renormalization can be computed fully non-perturbatively as a product of continuum step scaling matrices. These step scaling matrices are obtained by taking the "ratio" of Z matrices computed at different energies in an RI-MOM type scheme for which twisted boundary conditions are an essential ingredient. Our method allows us to relax the bounds of the Rome-Southampton window. We also explain why such a method is important in view of the light quark physics program of the RBC-UKQCD collaborations. To illustrate our method, using n_f=2+1 domain-wall fermions, we compute the non-perturbative running matrix of four-quark operators needed in K->pipi decay and neutral kaon mixing. Our results are then compared to perturbation theory.Comment: 8 pages, 7 figures. v2: PRD version, minor changes and few references adde

    About the parabolic relation existing between the skewness and the kurtosis in time series of experimental data

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    In this work we investigate the origin of the parabolic relation between skewness and kurtosis often encountered in the analysis of experimental time-series. We argue that the numerical values of the coefficients of the curve may provide informations about the specific physics of the system studied, whereas the analytical curve per se is a fairly general consequence of a few constraints expected to hold for most systems.Comment: To appear in Physica Script

    One-loop matching of improved four-fermion staggered operators with an improved gluon action

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    We present results for one-loop matching factors of four-fermion operators composed of HYP-smeared staggered fermions. We generalize previous calculations by using the tree-level improved Symanzik gauge action. These results are needed for our companion numerical calculation of BKB_K and related matrix elements. We find that the impact on one-loop matching factors of using the improved gluon action is much smaller than that from the use of either HYP smearing or mean-field improvement. The one-loop coefficients for mean-field improved, HYP-smeared operators with the Symanzik gauge action have a maximum magnitude of O(1)×αsO(1)\times \alpha_s, indicating that perturbation theory is reasonably convergent.Comment: 11 pages, 16 figures, references are update

    The relative influence of demographic, individual, social, and environmental factors on physical activity among boys and girls

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    Background: This study aimed to evaluate the associations of selected demographic, individual, social, and environmental factors with moderate-to-vigorous physical activity (MVPA) in a sample of children and adolescents. Methods: MVPA was assessed among youth (n = 294) 10-17-years-old using the ActiGraph accelerometer. Youth completed measures of demographic and individual variables related to physical activity (PA), perceived social support by parents and peers, and perceived neighborhood characteristics. Parents completed the long-form of the International Physical Activity Questionnaire. The Physical Activity and Media Inventory was used to measure the home environment and Geographical Information Systems software was used to measure the physical neighborhood environment. Bivariate correlations and hierarchical multiple regression were conducted stratified by gender. Results: Boys participated in significantly more MVPA than girls. In hierarchical analyses, peer support, home PA equipment, and temperature were significantly associated with MVPA among boys whereas distance to the school they attended was associated with MVPA among girls. The final models accounted for 25% and 15% of the variance in MVPA among boys and girls, respectively. Conclusions: Important differences exist among the individual, social, and environmental factors related to MVPA between boys and girls. Boys\u27 levels of activity appear to be influenced by factors closely linked to unstructured and social types of activities whereas girls\u27 activities relate to internal and external barriers as well as their proximity to their schools. The prospective contribution of these important individual, social, and environmental factors to changes in MVPA among children and adolescents remains to be determined
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