1,393 research outputs found

    Terrace reconstruction and long profile projection: a case study from the Solent river system near Southampton, England

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    River terrace sequences are important frameworks for archaeological evidence and as such it is important to produce robust correlations between what are often fragmentary remnants of ancient terraces. This paper examines both conceptual and practical issues related to such correlations, using a case study from the eastern part of the former Solent River system near Southampton, England. In this region two recent terrace schemes have been constructed using different data to describe the terrace deposits: one based mainly on terrace surfaces; the other on gravel thicknesses, often not recording the terrace surface itself. The utility of each of these types of data in terrace correlation is discussed in relation to the complexity of the record, the probability of post-depositional alteration of surface sediments and comparison of straight-line projections with modern river long profiles. Correlation using age estimates is also discussed, in relation to optically-stimulated luminescence dating of sand lenses within terrace gravels in this region during the PASHCC project. It is concluded that the need for replication at single sites means that this approach has limited use for correlative purposes, although dating of sediments is important for understanding wider landscape evolution and patterns of human occupation

    A micropillar for cavity optomechanics

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    We present a new micromechanical resonator designed for cavity optomechanics. We have used a micropillar geometry to obtain a high-frequency mechanical resonance with a low effective mass and a very high quality factor. We have coated a 60-μ\mum diameter low-loss dielectric mirror on top of the pillar and are planning to use this micromirror as part of a high-finesse Fabry-Perot cavity, to laser cool the resonator down to its quantum ground state and to monitor its quantum position fluctuations by quantum-limited optical interferometry

    Quantifying the Energetics and Length Scales of Carbon Segregation to Fe Symmetric Tilt Grain Boundaries Using Atomistic Simulations

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    Segregation of impurities to grain boundaries plays an important role in both the stability and macroscopic behavior of polycrystalline materials. The research objective in this work is to better characterize the energetics and length scales involved with the process of solute and impurity segregation to grain boundaries. Molecular dynamics simulations are used to calculate the segregation energies for carbon within multiple grain boundary sites over a database of 125 symmetric tilt grain boundaries in Fe. The simulation results show that the majority of atomic sites near the grain boundary have segregation energies lower than in the bulk. Moreover, depending on the boundary, the segregation energies approach the bulk value approximately 5-12 \AA\ away from the center of the grain boundary, providing an energetic length scale for carbon segregation. A subsequent data reduction and statistical representation of this dataset provides critical information such as about the mean segregation energy and the associated energy distributions for carbon atoms as a function of distance from the grain boundary, which quantitatively informs higher scale models with energetics and length scales necessary for capturing the segregation behavior of impurities in Fe. The significance of this research is the development of a methodology capable of ascertaining segregation energies over a wide range of grain boundary character (typical of that observed in polycrystalline materials), which herein has been applied to carbon segregation in a specific class of grain boundaries in iron

    Navigating the stigmatised identities of poverty in austere times: Resisting and responding to narratives of personal failure

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    © 2015, © The Author(s) 2015. Behavioural explanations of poverty and disadvantage have figured heavily in political rhetoric in the era of austerity, as a means to understand trajectories into poverty and subsequent relationships between benefit claimants and the state. These discourses are not restricted to political debate, as previous studies demonstrate they impact upon public consciousness and structure the ways that the general public think about poverty, as well as shaping the ways in which people living on low incomes are treated. Drawing upon the testimonies of 62 people in England and Scotland experiencing poverty, this article seeks to understand our participants’ responses to these discourses, in particular: how these behavioural explanations impact upon their understanding of their own situations, as well as their self perceptions; how these discourses shape their relationships with others, in terms of their experience of disrespect; and how participants seek to dissociate themselves from their stigmatising implications

    Breakdown of Scaling in the Nonequilibrium Critical Dynamics of the Two-Dimensional XY Model

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    The approach to equilibrium, from a nonequilibrium initial state, in a system at its critical point is usually described by a scaling theory with a single growing length scale, ξ(t)t1/z\xi(t) \sim t^{1/z}, where z is the dynamic exponent that governs the equilibrium dynamics. We show that, for the 2D XY model, the rate of approach to equilibrium depends on the initial condition. In particular, ξ(t)t1/2\xi(t) \sim t^{1/2} if no free vortices are present in the initial state, while ξ(t)(t/lnt)1/2\xi(t) \sim (t/\ln t)^{1/2} if free vortices are present.Comment: 4 pages, 3 figure

    Dynamics of gravity driven three-dimensional thin films on hydrophilic-hydrophobic patterned substrates

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    We investigate numerically the dynamics of unstable gravity driven three-dimensional thin liquid films on hydrophilic-hydrophobic patterned substrates of longitudinal stripes and checkerboard arrangements. The thin film can be guided preferentially on hydrophilic longitudinal stripes, while fingers develop on adjacent hydrophobic stripes if their width is large enough. On checkerboard patterns, the film fingering occurs on hydrophobic domains, while lateral spreading is favoured on hydrophilic domains, providing a mechanism to tune the growth rate of the film. By means of kinematical arguments, we quantitatively predict the growth rate of the contact line on checkerboard arrangements, providing a first step towards potential techniques that control thin film growth in experimental setups.Comment: 30 pages, 12 figure

    A systematic literature review and meta-analysis of community pharmacist-led interventions to optimise the use of antibiotics.

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    AIMS: The aim of this systematic review is to assess the effects of community pharmacist-led interventions to optimise the use of antibiotics and identify which interventions are most effective. METHODS: This review was conducted according to the PRISMA guidelines (PROSPERO: CRD42020188552). PubMed, EMBASE and the Cochrane Central Register of Controlled Trials were searched for (randomised) controlled trials. Included interventions were required to target antibiotic use, be set in the community pharmacy context, and be pharmacist-led. Primary outcomes were quality of antibiotic supply and adverse effects while secondary outcomes included patient-reported outcomes. Risk of bias was assessed using the 'Cochrane suggested risk of bias criteria' and narrative synthesis of primary outcomes conducted. RESULTS: Seventeen studies were included covering in total 3822 patients (mean age 45.6 years, 61.9% female). Most studies used educational interventions. Three studies reported on primary outcomes, 12 on secondary outcomes and two on both. Three studies reported improvements in quality of dispensing, interventions led to more intensive symptom assessment (up to 30% more advice given) and a reduction of over-the-counter supply up to 53%. Three studies led to higher consumer satisfaction, effects on adherence from nine studies were mixed (risk difference 0.04 [-0.02, 0.10]). All studies had unclear or high risks of bias across at least one domain, with large heterogeneity between studies. CONCLUSIONS: Our review suggests some positive results from pharmacist-led interventions, but the interventions do not seem sufficiently effective as currently implemented. This review should be interpreted as exploratory research, as more high-quality research is needed

    Multiscale correlative tomography: an investigation of creep cavitation in 316 stainless steel

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    Creep cavitation in an ex-service nuclear steam header Type 316 stainless steel sample is investigated through a multiscale tomography workflow spanning eight orders of magnitude, combining X-ray computed tomography (CT), plasma focused ion beam (FIB) scanning electron microscope (SEM) imaging and scanning transmission electron microscope (STEM) tomography. Guided by microscale X-ray CT, nanoscale X-ray CT is used to investigate the size and morphology of cavities at a triple point of grain boundaries. In order to understand the factors affecting the extent of cavitation, the orientation and crystallographic misorientation of each boundary is characterised using electron backscatter diffraction (EBSD). Additionally, in order to better understand boundary phase growth, the chemistry of a single boundary and its associated secondary phase precipitates is probed through STEM energy dispersive X-ray (EDX) tomography. The difference in cavitation of the three grain boundaries investigated suggests that the orientation of grain boundaries with respect to the direction of principal stress is important in the promotion of cavity formation

    Radiation-pressure cooling and optomechanical instability of a micro-mirror

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    Recent experimental progress in table-top experiments or gravitational-wave interferometers has enlightened the unique displacement sensitivity offered by optical interferometry. As the mirrors move in response to radiation pressure, higher power operation, though crucial for further sensitivity enhancement, will however increase quantum effects of radiation pressure, or even jeopardize the stable operation of the detuned cavities proposed for next-generation interferometers. The appearance of such optomechanical instabilities is the result of the nonlinear interplay between the motion of the mirrors and the optical field dynamics. In a detuned cavity indeed, the displacements of the mirror are coupled to intensity fluctuations, which modifies the effective dynamics of the mirror. Such "optical spring" effects have already been demonstrated on the mechanical damping of an electromagnetic waveguide with a moving wall, on the resonance frequency of a specially designed flexure oscillator, and through the optomechanical instability of a silica micro-toroidal resonator. We present here an experiment where a micro-mechanical resonator is used as a mirror in a very high-finesse optical cavity and its displacements monitored with an unprecedented sensitivity. By detuning the cavity, we have observed a drastic cooling of the micro-resonator by intracavity radiation pressure, down to an effective temperature of 10 K. We have also obtained an efficient heating for an opposite detuning, up to the observation of a radiation-pressure induced instability of the resonator. Further experimental progress and cryogenic operation may lead to the experimental observation of the quantum ground state of a mechanical resonator, either by passive or active cooling techniques
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