24,000 research outputs found

    Income and distance elasticities of values of travel time savings: New Swiss results

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    This paper presents the findings of a study looking into the valuation of travel time savings (VTTS) in Switzerland, across modes as well as across purpose groups. The study makes several departures from the usual practice in VTTS studies, with the main one being a direct representation of the income and distance elasticity of the VTTS measures. Here, important gains in model performance and significantly different results are obtained through this approach. Additionally, the analysis shows that the estimation of robust coefficients for congested car travel time is hampered by the low share of congested time in the overall travel time, and the use of an additional rate-of-congestion coefficient, in addition to a generic car travel time coefficient, is preferable. Finally, the analysis demonstrates that the population mean of the indicators calculated is quite different from the sample means and presents methods to calculate those, along with the associated variances. These variances are of great interest as they allow the generation of confidence intervals, which can be extremely useful in cost-benefit analyses

    The Guinea Pig Club: Forces and factors that revolutionised burns plastic surgery

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    The ‘Guinea Pig Club’ has been described as the most exclusive club in the world, but the entrance fee is something most men would care not to pay, and the conditions of membership are arduous in the extreme. The Guinea Pig Club was formed in July 1941 to support aircrew who were undergoing reconstructive plastic surgery after receiving burn injuries in the Second World War. This paper will explore the novel surgical techniques employed to treat the Guinea Pig Club members, their experiences at the hospital and their lives after the war and how Sir Archibald McIndoe and the Guinea Pig club members revolutionised burns plastic surgery as we know it today

    A search for rotating radio transients and fast radio bursts in the Parkes high-latitude pulsar survey

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    Discoveries of rotating radio transients and fast radio bursts (FRBs) in pulsar surveys suggest that more of such transient sources await discovery in archival data sets. Here we report on a single-pulse search for dispersed radio bursts over a wide range of Galactic latitudes (|b| < 6060^{\circ}) in data previously searched for periodic sources by Burgay et al. We re-detected 20 of the 42 pulsars reported by Burgay et al. and one rotating radio transient reported by Burke-Spolaor. No FRBs were discovered in this survey. Taking into account this result, and other recent surveys at Parkes, we corrected for detection sensitivities based on the search software used in the analyses and the different backends used in these surveys and find that the all-sky FRB event rate for sources with a fluence above 4.0 Jy ms at 1.4 GHz to be R=4.43.1+5.2×103{\cal R} = 4.4^{+5.2}_{-3.1} \times 10^3 FRBs day1^{-1} sky1^{-1}, where the uncertainties represent a 99%99\% confidence interval. While this rate is lower than inferred from previous studies, as we demonstrate, this combined event rate is consistent with the results of all systematic FRB searches at Parkes to date and does not require the need to postulate a dearth of FRBs at intermediate latitudes.Comment: Accepted, 10 pages, 6 figure

    J-factors of short DNA molecules

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    The propensity of short DNA sequences to convert to the circular form is studied by a mesoscopic Hamiltonian method which incorporates both the bending of the molecule axis and the intrinsic twist of the DNA strands. The base pair fluctuations with respect to the helix diameter are treated as path trajectories in the imaginary time path integral formalism. The partition function for the sub-ensemble of closed molecules is computed by imposing chain ends boundary conditions both on the radial fluctuations and on the angular degrees of freedom. The cyclization probability, the J-factor, proves to be highly sensitive to the stacking potential, mostly to its nonlinear parameters. We find that the J-factor generally decreases by reducing the sequence length ( N ) and, more significantly, below N = 100 base pairs. However, even for very small molecules, the J-factors remain sizeable in line with recent experimental indications. Large bending angles between adjacent base pairs and anharmonic stacking appear as the causes of the helix flexibility at short length scales.Comment: The Journal of Chemical Physics - May 2016 ; 9 page

    Molecular Weight Dependence of Polymersome Membrane Elasticity and Stability

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    Vesicles prepared in water from a series of diblock copolymers and termed "polymersomes" are physically characterized. With increasing molecular weight Mˉn\bar{M}_n, the hydrophobic core thickness dd for the self-assembled bilayers of polyethyleneoxide - polybutadiene (PEO-PBD) increases up to 20 nmnm - considerably greater than any previously studied lipid system. The mechanical responses of these membranes, specifically, the area elastic modulus KaK_a and maximal areal strain αc\alpha_c are measured by micromanipulation. As expected for interface-dominated elasticity, KaK_a (\simeq 100 pN/nmpN/nm) is found to be independent of Mˉn\bar{M}_n. Related mean-field ideas also predict a limiting value for αc\alpha_c which is universal and about 10-fold above that typical of lipids. Experiments indeed show αc\alpha_c generally increases with Mˉn\bar{M}_n, coming close to the theoretical limit before stress relaxation is opposed by what might be chain entanglements at the highest Mˉn\bar{M}_n. The results highlight the interfacial limits of self-assemblies at the nano-scale.Comment: 16 pages, 5 figures, and 1 tabl

    On invariant sets in Lagrangian graphs

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    In this exposition, we show that a Hamiltonian is always constant on a compact invariant connected subset which lies in a Lagrangian graph provided that the Hamiltonian and the graph are smooth enough. We also provide some counterexamples for the case that the Hamiltonians are not smooth enough.Comment: 4 page

    A review of human factors principles for the design and implementation of medication safety alerts in clinical information systems.

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    The objective of this review is to describe the implementation of human factors principles for the design of alerts in clinical information systems. First, we conduct a review of alarm systems to identify human factors principles that are employed in the design and implementation of alerts. Second, we review the medical informatics literature to provide examples of the implementation of human factors principles in current clinical information systems using alerts to provide medication decision support. Last, we suggest actionable recommendations for delivering effective clinical decision support using alerts. A review of studies from the medical informatics literature suggests that many basic human factors principles are not followed, possibly contributing to the lack of acceptance of alerts in clinical information systems. We evaluate the limitations of current alerting philosophies and provide recommendations for improving acceptance of alerts by incorporating human factors principles in their design

    Pulsar J0453+1559: A Double Neutron Star System with a Large Mass Asymmetry

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    To understand the nature of supernovae and neutron star (NS) formation, as well as binary stellar evolution and their interactions, it is important to probe the distribution of NS masses. Until now, all double NS (DNS) systems have been measured to have a mass ratio close to unity (q \geq 0.91). Here we report the measurement of the individual masses of the 4.07-day binary pulsar J0453+1559 from measurements of the rate of advance of periastron and Shapiro delay: The mass of the pulsar is 1.559(5) MM_{\odot} and that of its companion is 1.174(4) MM_{\odot}; q = 0.75. If this companion is also a neutron star (NS), as indicated by the orbital eccentricity of the system (e=0.11), then its mass is the smallest precisely measured for any such object. The pulsar has a spin period of 45.7 ms and a spin derivative of 1.8616(7) x101910^-19; from these we derive a characteristic age of ~ 4.1 x 10910^9 years and a magnetic field of ~ 2.9 x 10910^9 G,i.e, this pulsar was mildly recycled by accretion of matter from the progenitor of the companion star. This suggests that it was formed with (very approximately) its current mass. Thus NSs form with a wide range of masses, which is important for understanding their formation in supernovae. It is also important for the search for gravitational waves released during a NS-NS merger: it is now evident that we should not assume all DNS systems are symmetric
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