14,566 research outputs found

    First Class Call Stacks: Exploring Head Reduction

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    Weak-head normalization is inconsistent with functional extensionality in the call-by-name λ\lambda-calculus. We explore this problem from a new angle via the conflict between extensionality and effects. Leveraging ideas from work on the λ\lambda-calculus with control, we derive and justify alternative operational semantics and a sequence of abstract machines for performing head reduction. Head reduction avoids the problems with weak-head reduction and extensionality, while our operational semantics and associated abstract machines show us how to retain weak-head reduction's ease of implementation.Comment: In Proceedings WoC 2015, arXiv:1606.0583

    Testing the Role of Technical Information in Public Risk Perception

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    It is widely believed that more detail about health effects and likely exposure routes is apt to reduce citizens\u27 concerns about low-probability Risks. The authors\u27 study suggests that providing such detail may not be as useful as, e.g., addressing public concerns and keeping citizens current on officials\u27 actions

    County-Specific Net Migration by Five-Year Age Groups, Hispanic Origin, Race and Sex 2000-2010

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    This report documents the methodology used to prepare county-level, net migration estimates by five-year age cohorts and sex, and by race and Hispanic origin, for the intercensal period from 2000 to 2010. The estimates were prepared using a vital statistics version of the forward cohort residual method (Siegel and Hamilton 1952) following the techniques used to prepare the 1990 to 2000 net migration estimates (Voss, McNiven, Johnson, Hammer, and Fuguitt 2004) as described in detail below. These numbers (and the net migration rates derivable from them) extend the set of decennial estimates of net migration that have been produced following each decennial census beginning with 1960 (net migration for the 1950s: Bowles and Tarver, 1965; 1960s: Bowles, Beale and Lee, 1975; 1970s: White, Mueser and Tierney, 1987; 1980s: Fuguitt, Beale, and Voss 2010; and 1990s: Voss, McNiven, Hammer, Johnson and Fuguitt, 2004)

    AFM imaging and plasmonic detection of organic thin-films deposited on nanoantenna arrays

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    In this study, atomic force microscopy (AFM) imaging has been used to reveal the preferential deposition of organic thin-films on patterned nanoantenna array surfaces - identifying the localised formation of both monolayer and multilayer films of octadecanethiol (ODT) molecules, depending on the concentration of the solutions used. Reliable identification of this selective deposition process has been demonstrated for the first time, to our knowledge. Organic thin-films, in particular films of ODT molecules, were deposited on plasmonic resonator surfaces through a chemi-sorption process - using different solution concentrations and immersion times. The nanoantennas based on gold asymmetric-split ring resonator (A-SRR) geometries were fabricated on zinc selenide (ZnSe) substrates using electron-beam lithography and the lift-off technique. Use of the plasmonic resonant-coupling technique has enabled the detection of ODT molecules deposited from a dilute, micromolar (1 M) solution concentration - with attomole sensitivity of deposited material per A-SRR – a value that is three orders of magnitude lower in concentration than previously reported. Additionally, on resonance, the amplitude of the molecular vibrational resonance peaks is typically an order of magnitude larger than that for the non-resonant coupling. Fourier-transform infrared (FTIR) spectroscopy shows molecule specific spectral responses – with magnitudes corresponding to the different film thicknesses deposited on the resonator surfaces. The experimental results are supported by numerical simulation

    Deposition of Organic Molecules on Gold Nanoantennas for Sensing

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    The deposition of organic molecules on gold nanoantennas is reported through chemisorption for sensing in the midinfrared (mid-IR) spectral range. The specific nanostructures are gold asymmetric-split ring resonators (A-SRRs) based on circular-geometry with two different ‘arc’ lengths. The plasmonic resonant coupling technique was used to match the vibrational responses of the targeted molecules for their enhanced detection. Gold nanostructures are functionalised through chemisorption of octadecanethiol (ODT) in ethanol solution. The molecular vibrational responses were measured using a microscope coupled Fourier Transform Infrared (FTIR) spectroscopy. The experimental findings are closely supported using FDTD simulation. The modified nanoantennas surfaces are capable of supporting wide range of organic-sensing applications

    Paul Johnson’s Brief Life of Churchill

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    Posttraumatic Attenuation of the Lisfranc Ligament in a 14-Year-Old Athlete: A Case Report

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    Lisfranc injuries in children are rare and range from mild midfoot sprains to severe traumatic fracture-dislocations. Management of sprains is nonoperative, whereas treatment of fracture-dislocations often requires internal fixation. We present a unique case of a midfoot sprain in a 14-year-old adolescent boy, with gradual increased instability at the joint owing to attenuation of the Lisfranc ligament. Closed reduction and percutaneous pinning resulted in successful treatment at 3 weeks postoperatively. Midfoot sprains may lead to further ligamentous attenuation and widening as seen on radiographs and thus should be monitored for signs of persistent pain and instability. Because midfoot instability contributes considerably to posttraumatic arthritis, we recommend reduction when nonoperative interventions are unsuccessful
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