14,781 research outputs found

    Ultrasonic scanner for radial and flat panels

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    An ultrasonic scanning mechanism is described that scans panels of honeycomb construction or with welded seams. It incorporates a device which by simple adjustment is adapted to scan either a flat panel or a radial panel. The supporting structure takes the form of a pair of spaced rails. An immersion tank is positioned between the rails and below their level. A work holder is mounted in the tank and is adapted to hold the flat or radial panel. A traveling bridge is movable along the rails and a carriage is mounted on the bridge

    LANDSAT D local user terminal study

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    The effect of the changes incorporated in the LANDSAT D system on the ability of a local user terminal to receive, record and process data in real time was studied. Alternate solutions to the problems raised by these changes were evaluated. A loading analysis was performed in order to determine the quantities of data that a local user terminal (LUT) would be interested in receiving and processing. The number of bits in an MSS and a TM scene were calculated along with the number of scenes per day that an LUT might require for processing. These then combined to a total number of processed bits/day for an LUT as a function of sensor and coverage circle radius

    Distribution and partitioning of heavy metals in estuarine sediment cores and implications for the use of sediment quality standards

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    International audienceTotal metal concentrations in surface sediments and historically contaminated sediments were determined in sediment cores collected from three estuaries (Thames, Medway and Blackwater) in south-east England. The partitioning behaviour of metals in these sediments was also determined using a sequential extraction scheme. These data were then compared with sediment quality values (SQVs) to determine the potential ecotoxicological risk to sediment dwelling organisms. When total metal concentrations in surface sediments are examined, no risk to biota in any of the estuaries is indicated. However, when historically contaminated sediments at depth are also considered, risks to biota are apparent and are greatest for the Thames, followed by the Medway and then the Blackwater. This suggests that regulatory authorities should examine vertical metal profiles, particularly in estuaries that are experiencing low sediment accumulation rates where historically contaminated sediments are in the shallow sub-surface zone and where erosion or dredging activities may take place. When metal partitioning characteristics are also considered, the risk to biota is comparable for the Medway and the Blackwater with the potentially bioavailable fraction presenting no ecotoxicological risk. Conversely, over 70% of metals are labile in the Thames Estuary sediments and toxic effects are probable. This suggests that the application of SQVs using total sediment metal concentrations may over- or under-estimate the risk to biota in geochemically dissimilar estuarine sediments. Keywords: sediment quality values, estuarine sediments, metal contamination, partitioning, sequential extraction</p

    Video Self-reflection and Coach Development in New Zealand

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    Drawing on data from semi-structured interviews with New Zealand coaches (N = 6), this study examined how video self-reflection (VSR) was perceived as a tool for learning within ‘on-going’ coach development. This study also looked to determine the potential barriers experienced by coaches before engaging in VSR. Each participant was a performance coach (as identified by the NZ coach development framework (CDF)) with 5+ years coaching experience and had recently (in the previous 12 months) participated in a coach development program that aligned with Sport NZ’s CDF. Five main themes emerged from the data; coaches had a positive perception of the benefits of VSR, a desire to engage in VSR but did not prioritise the time, logistical concerns, a fear of self-confrontation and evidence of knowledge for ‘modern’ coaching development. Findings indicated that coaches valued VSR as a tool for learning; however, the lack of exposure and experience in the process meant coaches did not value the practise enough to dedicate specific time towards it. This study provides an evidence-base that can be used to support National Governing Bodies coach development frameworks, and the modification of content to encourage the use of VSR as a tool for learning

    Cold atom confinement in an all-optical dark ring trap

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    We demonstrate confinement of 85^{85}Rb atoms in a dark, toroidal optical trap. We use a spatial light modulator to convert a single blue-detuned Gaussian laser beam to a superposition of Laguerre-Gaussian modes that forms a ring-shaped intensity null bounded harmonically in all directions. We measure a 1/e spin-relaxation lifetime of ~1.5 seconds for a trap detuning of 4.0 nm. For smaller detunings, a time-dependent relaxation rate is observed. We use these relaxation rate measurements and imaging diagnostics to optimize trap alignment in a programmable manner with the modulator. The results are compared with numerical simulations.Comment: 5 pages, 4 figure

    Magnetically-controlled velocity selection in a cold atom sample using stimulated Raman transitions

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    We observe velocity-selective two-photon resonances in a cold atom cloud in the presence of a magnetic field. We use these resonances to demonstrate a simple magnetometer with sub-mG resolution. The technique is particularly useful for zeroing the magnetic field and does not require any additional laser frequencies than are already used for standard magneto-optical traps. We verify the effects using Faraday rotation spectroscopy.Comment: 5 pages, 6 figure

    Model of surface instabilities induced by stress

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    We propose a model based on a Ginzburg-Landau approach to study a strain relief mechanism at a free interface of a non-hydrostatically stressed solid, commonly observed in thin-film growth. The evolving instability, known as the Grinfeld instability, is studied numerically in two and three dimensions. Inherent in the description is the proper treatment of nonlinearities. We find these nonlinearities can lead to competitive coarsening of interfacial structures, corresponding to different wavenumbers, as strain is relieved. We suggest ways to experimentally measure this coarsening.Comment: 4 pages (3 figures included

    Nowhere to Run; Nowhere to Hide: The Reality of Being a Law Library Director in Times of Great Opportunity and Significant Challenges

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    This is an edited version of remarks presented at \u27Nowhere to Run, Nowhere to Hide\u27: The Reality of Being a Law Library Director in Times of Great Opportunity and Significant Challenges, January 5, 2015, at the Association of American Law Schools Annual Meeting, Washington, D.C

    Characterization of Hypertension Risk Factors at the Committee on Temporary Shelter

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    Introduction: The health of homeless populations is at risk due to a high prevalence of undiagnosed hypertension (HTN) and cardiovascular disease (CVD). The interaction of housing and socioeconomic status with the risk factors for HTN and CVD remains unclear. Prevention of HTN through a healthy diet, exercise, adequate sleep, and avoidance of tobacco has been well described, but financial limitations and competing priorities for shelter and food make blood pressure (BP) control difficult for this population. By characterizing the risk factors and awareness of hypertension within the homeless population at the Committee on Temporary Shelter Daystation (COTS) in Burlington, Vermont, we may be able to identify promising avenues for therapeutic intervention.https://scholarworks.uvm.edu/comphp_gallery/1226/thumbnail.jp
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