2,372 research outputs found

    Using an audit tool (MAPS Global) to assess the characteristics of the physical environment related to walking for transport in youth : reliability of Belgian data

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    Background: The aim was to examine inter-rater and alternate-form reliability of the Microscale Audit of Pedestrian Streetscapes (MAPS) Global tool to assess the physical environment along likely walking routes in Belgium. Methods: For 65 children participating in the BEPAS-children study, routes between their individual homes and the nearest pre-defined destination were defined. Using MAPS Global, physical environmental characteristics of the routes were audited by 4 trained auditors (2 on-site, 2 online using Google Street View). Inter-rater reliability was studied for on-site and online ratings separately. Alternate-form reliability was examined by comparing on-site with online ratings. Results: Inter-rater reliability for on-site ratings was acceptable for 68% of items (kappa range 0.03–1.00) and for online ratings for 60% of items (kappa range −0.03 to 1.00). Acceptable alternate-form reliability was reported for 60% of items (kappa range −0.01 to 1.00/r range 0.31–1.00). Conclusions: MAPS Global can be used to assess the physical environment of potential walking routes. For areas where Google Street View imagery is widely covered and often updated, MAPS Global can be completed online

    Modelling CO emission from Mira's wind

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    We have modelled the circumstellar envelope of {\it o} Ceti (Mira) using new observational constraints. These are obtained from photospheric light scattered in near-IR vibrational-rotational lines of circumstellar CO molecules at 4.6 micron: absolute fluxes, the radial dependence of the scattered intensity, and two line ratios. Further observational constraints are provided by ISO observations of far-IR emission lines from highly excited rotational states of the ground vibrational state of CO, and radio observations of lines from rotational levels of low excitation of CO. A code based on the Monte-Carlo technique is used to model the circumstellar line emission. We find that it is possible to model the radio and ISO fluxes, as well as the highly asymmetric radio-line profiles, reasonably well with a spherically symmetric and smooth stellar wind model. However, it is not possible to reproduce the observed NIR line fluxes consistently with a `standard model' of the stellar wind. This is probably due to incorrectly specified conditions of the inner regions of the wind model, since the stellar flux needs to be larger than what is obtained from the standard model at the point of scattering, i.e., the intermediate regions at approximately 100-400 stellar radii (2"-7") away from the star. Thus, the optical depth in the vibrational-rotational lines from the star to the point of scattering has to be decreased. This can be accomplished in several ways. For instance, the gas close to the star (within approximately 2") could be in such a form that light is able to pass through, either due to the medium being clumpy or by the matter being in radial structures (which, further out, developes into more smooth or shell-like structures).Comment: 18 pages, 3 figures, accepted for publication in Ap

    Identifying conducive contexts and working mechanisms of sedentary behaviour interventions in older adults: a realist review protocol as part of the 'Stand UP Seniors' project

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    INTRODUCTION: Lifestyle behaviours, including sedentary behaviour, have been listed as key modifiable factors to promote healthy ageing. Sedentary behaviour is ubiquitous in older adults and has a strong link with age-related functional declines and chronic health conditions. Although several interventions have been developed aimed at the reduction of sedentary behaviour in older adults, little in-depth information is available on how these complex interventions work in different contexts. Therefore, the aim of our study was to unpack the mechanisms of how existing interventions aimed at the reduction of older adults’ sedentary behaviour work or fail to work in particular contexts in order to optimise the development and implementation of future sedentary behaviour interventions. METHODS AND ANALYSIS: A realist review will be conducted as a first part of the Stand UP Seniors (SUPS) project and will be structured as follows: (1) defining the scope of the review, (2) searching and appraising the evidence, (3) extracting data and synthesising the results, and (4) drawing conclusions and formulating recommendations. The result of this iterative process will be a final programme theory that can be used to identify which context triggers which mechanism, and in turn might elicit which outcome. The final programme theory will be used to inform the second and the third parts of the SUPS project, which are, respectively, the development and evaluation of a sedentary behaviour intervention in older adults. ETHICS AND DISSEMINATION: Ethical approval is not required for the review. Dissemination of the realist review results, including the final programme theory, will occur through peer-reviewed publications and presentations at relevant conferences. The peer-reviewed realist review will be prepared according to the Realist and Meta-narrative Evidence Synthesis: Evolving Standards publication standards for realist syntheses. PROSPERO REGISTRATION NUMBER: CRD42021248795

    Penning traps as a versatile tool for precise experiments in fundamental physics

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    This review article describes the trapping of charged particles. The main principles of electromagnetic confinement of various species from elementary particles to heavy atoms are briefly described. The preparation and manipulation with trapped single particles, as well as methods of frequency measurements, providing unprecedented precision, are discussed. Unique applications of Penning traps in fundamental physics are presented. Ultra-precise trap-measurements of masses and magnetic moments of elementary particles (electrons, positrons, protons and antiprotons) confirm CPT-conservation, and allow accurate determination of the fine-structure constant alpha and other fundamental constants. This together with the information on the unitarity of the quark-mixing matrix, derived from the trap-measurements of atomic masses, serves for assessment of the Standard Model of the physics world. Direct mass measurements of nuclides targeted to some advanced problems of astrophysics and nuclear physics are also presented

    Observing the spin of a free electron

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    Long ago, Bohr, Pauli, and Mott argued that it is not, in principle, possible to measure the spin components of a free electron. One can try to use a Stern-Gerlach type of device, but the finite size of the beam results in an uncertainty of the splitting force that is comparable with the gradient force. The result is that no definite spin measurement can be made. Recently there has been a revival of interest in this problem, and we will present our own analysis and quantum-mechanical wave-packet calculations which suggest that a spin measurement is possible for a careful choice of initial conditions

    Mira's wind explored in scattering infrared CO lines

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    We have observed the intermediate regions of the circumstellar envelope of Mira (o Ceti) in photospheric light scattered by three vibration-rotation transitions of the fundamental band of CO, from low-excited rotational levels of the ground vibrational state, at an angular distance of beta = 2"-7" away from the star. The data were obtained with the Phoenix spectrometer mounted on the 4 m Mayall telescope at Kitt Peak. The spatial resolution is approximately 0.5" and seeing limited. Our observations provide absolute fluxes, leading to an independent new estimate of the mass-loss rate of approximately 3e-7 Msun/yr, as derived from a simple analytic wind model. We find that the scattered intensity from the wind of Mira for 2" < beta < 7" decreases as beta^-3, which suggests a time constant mass-loss rate, when averaged over 100 years, over the past 1200 years.Comment: accepted for publication in the Astrophysical Journa

    Electron-radiation interaction in a Penning trap: beyond the dipole approximation

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    We investigate the physics of a single trapped electron interacting with a radiation field without the dipole approximation. This gives new physical insights in the so-called geonium theory.Comment: 12 pages, RevTeX, 6 figures, Approved for publication in Phys. Rev.

    Quantum Logic with a Single Trapped Electron

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    We propose the use of a trapped electron to implement quantum logic operations. The fundamental controlled-NOT gate is shown to be feasible. The two quantum bits are stored in the internal and external (motional) degrees of freedom.Comment: 7 Pages, REVTeX, No Figures, To appear in Phys. Rev.

    Stellar Iron Abundances at the Galactic Center

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    We present measurements of [Fe/H] for six M supergiant stars and three giant stars within 0.5 pc of the Galactic Center (GC) and one M supergiant star within 30 pc of the GC. The results are based on high-resolution (lambda / Delta lambda =40,000) K-band spectra, taken with CSHELL at the NASA Infrared Telescope Facility.We determine the iron abundance by detailed abundance analysis,performed with the spectral synthesis program MOOG.The mean [Fe/H] of the GC stars is determined to be near solar,[Fe/H] = +0.12 ±\pm 0.22. Our analysis is a differential analysis, as we have observed and applied the same analysis technique to eleven cool, luminous stars in the solar neighborhood with similar temperatures and luminosities as the GC stars. The mean [Fe/H] of the solar neighborhood comparison stars, [Fe/H] = +0.03 ±\pm 0.16, is similar to that of the GC stars. The width of the GC [Fe/H] distribution is found to be narrower than the width of the [Fe/H] distribution of Baade's Window in the bulge but consistent with the width of the [Fe/H] distribution of giant and supergiant stars in the solar neighborhood.Comment: 41 pages, 9 figures, ApJ, in pres
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