9,591 research outputs found

    Interactions between rail and road safety in Great Britain

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    This paper discusses the results of an investigation into ways in which the safety risks of travel on road and rail interact with each other in Great Britain, other than through physical contact such as at level crossings. The two main foci of the paper are: (1) an analysis of the 'whole journey' risks of journeys for which the national rail system is the main mode, but which also include stages by other transport modes to provide access to the railway system: and (2) an analysis of the effect on safety risk of inter-modal transfers between rail and road. On (1), walking to and from stations was estimated to account on average for 65% of the overall door-to-door risk of being killed on rail journeys: the rail system itself accounts for 21% of the risk, and other access modes account for the remaining 14%. The average distance walked to and from stations is 0.9 km per rail journey, and this walking accounts for 5% of all walking nationally. On (2), it was found that increasing rail fares to fund railway safety measures may lead passengers to switch from rail to car, but for most sensible rail safety measures, the additional risks from such diversions are small compared with the intended rail safety benefits. However, for high-cost rail safety measures funded by passengers, the additional risks from diversions may be of the same order as the intended safety benefits. The last section of the paper explores the effects of variations in the casualty rates of rail users as pedestrians and car users. because their road risks may be different from those of all road users. Such variations could alter the detailed conclusions of the paper, but the scale of such effects appears to be modest. (c) 2008 Elsevier Ltd. All rights reserved

    Sub‐annual moraine formation at an active temperate Icelandic glacier

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    This paper presents detailed geomorphological and sedimentological investigations of small recessional moraines at Fjallsjökull, an active temperate outlet of Öræfajökull, southeast Iceland. The moraines are characterised by striking sawtooth or hairpin planforms, which are locally superimposed, giving rise to a complex spatial pattern. We recognise two distinct populations of moraines, namely a group of relatively prominent moraine ridges (mean height ~1.2 m) and a group of comparatively low‐relief moraines (mean height ~0.4 m). These two groups often occur in sets/systems, comprising one pronounced outer ridge and several inset smaller moraines. Using a representative subsample of the moraines, we establish that they form by either (i) submarginal deformation and squeezing of subglacial till or (ii) pushing of extruded tills. Locally, proglacial (glaciofluvial) sediments are also incorporated within the moraines during pushing. For the first time, to our knowledge, we demonstrate categorically that these moraines formed sub‐annually using repeat uncrewed aerial vehicle (UAV) imagery. We present a conceptual model for sub‐annual moraine formation at Fjallsjökull that proposes the sawtooth moraine sequence comprises (i) sets of small squeeze moraines formed during melt‐driven squeeze events and (ii) larger push moraines formed during winter re‐advances. We suggest the development of this process‐form regime is linked to a combination of elevated temperatures, high surface meltwater fluxes to the bed, and emerging basal topography (a depositional overdeepening). These factors result in highly saturated subglacial sediments and high porewater pressures, which induces submarginal deformation and ice‐marginal squeezing during the melt season. Strong glacier recession during the summer, driven by elevated temperatures, allows several squeeze moraines to be emplaced. This process‐form regime may be characteristic of active temperate glaciers receding into overdeepenings during phases of elevated temperatures, especially where their englacial drainage systems allow efficient transfer of surface meltwater to the glacier bed near the snout margin

    Local Volatility Calibration by Optimal Transport

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    The calibration of volatility models from observable option prices is a fundamental problem in quantitative finance. The most common approach among industry practitioners is based on the celebrated Dupire's formula [6], which requires the knowledge of vanilla option prices for a continuum of strikes and maturities that can only be obtained via some form of price interpolation. In this paper, we propose a new local volatility calibration technique using the theory of optimal transport. We formulate a time continuous martingale optimal transport problem, which seeks a martingale diffusion process that matches the known densities of an asset price at two different dates, while minimizing a chosen cost function. Inspired by the seminal work of Benamou and Brenier [1], we formulate the problem as a convex optimization problem, derive its dual formulation, and solve it numerically via an augmented Lagrangian method and the alternative direction method of multipliers (ADMM) algorithm. The solution effectively reconstructs the dynamic of the asset price between the two dates by recovering the optimal local volatility function, without requiring any time interpolation of the option prices

    ‘Context is King’ when Interpreting Match Physical Performances

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    ‘I was blind, now I can see’. Thus, is it time to retire the ‘blind’ distance covered model that’s been used in football for decades and replace it with an integrated model that contextualises physical efforts during matches

    Bench-to-bedside review: Inhaled nitric oxide therapy in adults

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    Nitric oxide (NO) is an endogenous mediator of vascular tone and host defence. Inhaled nitric oxide (iNO) results in preferential pulmonary vasodilatation and lowers pulmonary vascular resistance. The route of administration delivers NO selectively to ventilated lung units so that its effect augments that of hypoxic pulmonary vasoconstriction and improves oxygenation. This 'Bench-to-bedside' review focuses on the mechanisms of action of iNO and its clinical applications, with emphasis on acute lung injury and the acute respiratory distress syndrome. Developments in our understanding of the cellular and molecular actions of NO may help to explain the hitherto disappointing results of randomised controlled trials of iNO

    The Use of Unregulated Staff: Time for Regulation?

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    Internationally, shortages in the nursing workforce, escalating patient demands, and financial constraints within the health system have led to the growth of unlicensed nursing support workers. Recently, in relation to the largest publicly funded health system (National Health Service), it was reported that extensive substitution of registered nurses with unskilled nursing support workers resulted in inadequate patient care, increased morbidity and mortality rates, and negative nurse outcomes. We argue that it is timely to consider regulation of nursing support workers with their role and scope of practice clearly defined. Further, the addition of these workers in a complementary model of care (rather than substitutive model) should also be explored in future research, in terms of impact on patient and nurse outcomes. © The Author(s) 2014 Reprints and permissions:]br]sagepub.co.uk/journalsPermissions.nav
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