58,477 research outputs found

    National level promotion of physical activity: results from England's ACTIVE for LIFE campaign.

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    STUDY OBJECTIVE: To assess the impact of a national campaign on awareness of the campaign, change in knowledge of physical activity recommendations and self reported physical activity. DESIGN: three year prospective longitudinal survey using a multi-stage, cluster random probability design to select participants. SETTING: England. PARTICIPANTS: A nationally representative sample of 3189 adults aged 16-74 years. MAIN OUTCOME MEASURES: Awareness of the advertising element of the campaign, changes in knowledge of physical activity recommendations for health and self reported physical activity. RESULTS: 38% of participants were aware of the main advertising images, assessed six to eight months after the main television advertisement. The proportion of participants knowledgeable about moderate physical activity recommendations increased by 3.0% (95% CI: 1.4%, 4.5%) between waves 1 and 2 and 3.7% (95% CI: 2.1%, 5.3%) between waves 1 and 3. The change in proportion of active people between baseline and waves 1 and 2 was -0.02 (95% CI: -2.0 to +1.7) and between waves 1 and 3 was -9.8 (-7.9 to -11.7). CONCLUSION: The proportion of participants who were knowledgeable about the new recommendations, increased significantly after the campaign. There was however, no significant difference in knowledge by awareness of the main campaign advertisement. There is no evidence that ACTIVE for LIFE improved physical activity, either overall or in any subgroup

    Photoresist patterned thick-film piezoelectric elements on silicon

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    A fundamental limitation of screen printing is the achievable alignment accuracy and resolution. This paper presents details of a thick-resist process that improves both of these factors. The technique involves exposing/developing a thick resist to form the desired pattern and then filling the features with thick film material using a doctor blading process. Registration accuracy comparable with standard photolithographic processes has been achieved resulting in minimum feature sizes of <50 ?m and a film thickness of 100 ?m. Piezoelectric elements have been successfully poled on a platinised silicon wafer with a measured d 33 value of 60 pCN?1

    Hubbard-model description of the high-energy spin-spectral-weight distribution in La(2)CuO(4)

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    The spectral-weight distribution in recent neutron scattering experiments on the parent compound La2_2CuO4_4 (LCO), which are limited in energy range to about 450\,meV, is studied in the framework of the Hubbard model on the square lattice with effective nearest-neighbor transfer integral tt and on-site repulsion UU. Our study combines a number of numerical and theoretical approaches, including, in addition to standard treatments, density matrix renormalization group calculations for Hubbard cylinders and a suitable spinon approach for the spin excitations. Our results confirm that the U/8tU/8t magnitude suitable to LCO corresponds to intermediate UU values smaller than the bandwidth 8t8t, which we estimate to be 8t≈2.368t \approx 2.36 eV for U/8t≈0.76U/8t\approx 0.76. This confirms the unsuitability of the conventional linear spin-wave theory. Our theoretical studies provide evidence for the occurrence of ground-state d-wave spinon pairing in the half-filled Hubbard model on the square lattice. This pairing applies only to the rotated-electron spin degrees of freedom, but it could play a role in a possible electron d-wave pairing formation upon hole doping. We find that the higher-energy spin spectral weight extends to about 566 meV and is located at and near the momentum [π,π][\pi,\pi]. The continuum weight energy-integrated intensity vanishes or is extremely small at momentum [π,0][\pi,0]. This behavior of this intensity is consistent with that of the spin waves observed in recent high-energy neutron scattering experiments, which are damped at the momentum [π,0][\pi,0]. We suggest that future LCO neutron scattering experiments scan the energies between 450 meV and 566 meV and momenta around [π,π][\pi,\pi].Comment: 23 pages, 5 figure

    Large Scale Power Spectrum from Peculiar Velocities Via Likelihood Analysis

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    The power spectrum (PS) of mass density fluctuations, independent of `biasing', is estimated from the Mark III catalog of peculiar velocities using Bayesian statistics. A parametric model is assumed for the PS, and the free parameters are determined by maximizing the probability of the model given the data. The method has been tested using detailed mock catalogs. It has been applied to generalized CDM models with and without COBE normalization. The robust result for all the models is a relatively high PS, with P(k)Ω1.2=(4.8±1.5)×103(Mpc/h)3P(k) \Omega^{1.2} = (4.8 \pm 1.5) \times 10^3 (Mpc/h)^3 at k=0.1h/Mpck=0.1 h/Mpc. An extrapolation to smaller scales using the different CDM models yields σ8Ω0.6=0.88±0.15\sigma_8 \Omega^{0.6} = 0.88 \pm 0.15. The peak is weakly constrained to the range 0.02≀k≀0.06h/Mpc0.02 \leq k \leq 0.06 h/Mpc. These results are consistent with a direct computation of the PS (Kolatt & Dekel 1996). When compared to galaxy-density surveys, the implied values for ÎČ\beta (≥Ω0.6/b\equiv \Omega^{0.6}/b) are of order unity to within 25%. The parameters of the COBE-normalized, flat CDM model are confined by a 90% likelihood contour of the sort Ωh50ÎŒnÎœ=0.8±0.2\Omega h_{50}^\mu n^\nu = 0.8 \pm 0.2, where ÎŒ=1.3\mu = 1.3 and Îœ=3.4,2.0\nu = 3.4, 2.0 for models with and without tensor fluctuations respectively. For open CDM the powers are ÎŒ=0.95\mu = 0.95 and Îœ=1.4\nu = 1.4 (no tensor fluctuations). A Γ\Gamma-shape model free of COBE normalization yields only a weak constraint: Γ=0.4±0.2\Gamma = 0.4 \pm 0.2.Comment: 19 pages, 8 figures, 2 tables. Accepted for publication in The Astrophysical Journa

    Tracing Galaxy Assembly: Tadpole Galaxies in the Hubble Ultra Deep Field

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    In the Hubble Ultra Deep Field (HUDF) an abundance of galaxies is seen with a knot at one end plus an extended tail, resembling a tadpole. These "tadpole galaxies" appear dynamically unrelaxed--presumably in an early merging state--where tidal interactions likely created the distorted knot-plus-tail morphology. Here we systematically select tadpole galaxies from the HUDF and study their properties as a function of their photometric redshifts. In a companion HUDF variability study, Cohen et al. (2005) revealed a total of 45 variable objects believed to be Active Galactic Nuclei (AGN). Here we show that this faint AGN sample has no overlap with the tadpole galaxy sample, as predicted by theoretical work. The tadpole morphology--combined with the lack of overlap with the variable objects--supports the idea that these galaxies are in the process of an early-stage merger event, i.e., at a stage that likely precedes the "turn-on" of any AGN component and the onset of any point-source variability.Comment: 7 pages, 4 figures. Accepted for publication by Astrophysical Journa

    Surveys of Galaxy Clusters with the Sunyaev Zel'dovich Effect

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    We have created mock Sunyaev-Zel'dovich effect (SZE) surveys of galaxy clusters using high resolution N-body simulations. To the pure surveys we add `noise' contributions appropriate to instrument and primary CMB anisotropies. Applying various cluster finding strategies to these mock surveys we generate catalogues which can be compared to the known positions and masses of the clusters in the simulations. We thus show that the completeness and efficiency that can be achieved depend strongly on the frequency coverage, noise and beam characteristics of the instruments, as well as on the candidate threshold. We study the effects of matched filtering techniques on completeness, and bias. We suggest a gentler filtering method than matched filtering in single frequency analyses. We summarize the complications that arise when analyzing the SZE signal at a single frequency, and assess the limitations of such an analysis. Our results suggest that some sophistication is required when searching for `clusters' within an SZE map.Comment: 8 pages, 7 figure

    Fluctuation Spectrum from a Scalar-Tensor Bimetric Gravity Theory

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    Predictions of the CMB spectrum from a bimetric gravity theory (gr-qc/0101126) are presented. The initial inflationary period in BGT is driven by a vanishingly small speed of gravitational waves v_g in the very early universe. This initial inflationary period is insensitive to the choice of scalar field potential and initial values of the scalar field. After this initial period of inflation, v_g will increase rapidly and the effects of a potential will become important. We show that a quadratic potential introduced into BGT yields an approximately flat spectrum with inflation parameters: n_s=0.98, n_t=-0.027, alpha_s=-3.2e-4 and alpha_t=-5.0e-4, with r >= 0.014.Comment: 14 pages, uses amsmath, amssym

    Laser frequency locking by direct measurement of detuning

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    We present a new method of laser frequency locking in which the feedback signal is directly proportional to the detuning from an atomic transition, even at detunings many times the natural linewidth of the transition. Our method is a form of sub-Doppler polarization spectroscopy, based on measuring two Stokes parameters (I2I_2 and I3I_3) of light transmitted through a vapor cell. This extends the linear capture range of the lock loop by up to an order of magnitude and provides equivalent or improved frequency discrimination as other commonly used locking techniques.Comment: 4 pages, 4 figures Revte
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