7,584 research outputs found

    On the relationships between self-reported bicycling injuries and perceived risk among cyclists in Queensland, Australia

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    The focus of governments on increasing active travel has motivated renewed interest in cycling safety. Bicyclists are up to 20 times more likely to be involved in serious injury crashes than drivers so understanding the relationship among factors in bicyclist crash risk is critically important for identifying effective policy tools, for informing bicycle infrastructure investments, and for identifying high risk bicycling contexts. This study aims to better understand the complex relationships between bicyclist self reported injuries resulting from crashes (e.g. hitting a car) and non-crashes (e.g. spraining an ankle) and perceived risk of cycling as a function of cyclist exposure, rider conspicuity, riding environment, rider risk aversion, and rider ability. Self reported data from 2,500 Queensland cyclists are used to estimate a series of seemingly unrelated regressions to examine the relationships among factors. The major findings suggest that perceived risk does not appear to influence injury rates, nor do injury rates influence perceived risks of cycling. Riders who perceive cycling as risky tend not to be commuters, do not engage in group riding, tend to always wear mandatory helmets and front lights, and lower their perception of risk by increasing days per week of riding and by increasing riding proportion on bicycle paths. Riders who always wear helmets have lower crash injury risk. Increasing the number of days per week riding tends to decrease both crash injury and non crash injury risk (e.g. a sprain). Further work is needed to replicate some of the findings in this study

    Cosmic microwave background constraints on the epoch of reionization

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    We use a compilation of cosmic microwave anisotropy data to constrain the epoch of reionization in the Universe, as a function of cosmological parameters. We consider spatially-flat cosmologies, varying the matter density Ω0\Omega_0 (the flatness being restored by a cosmological constant), the Hubble parameter hh and the spectral index nn of the primordial power spectrum. Our results are quoted both in terms of the maximum permitted optical depth to the last-scattering surface, and in terms of the highest allowed reionization redshift assuming instantaneous reionization. For critical-density models, significantly-tilted power spectra are excluded as they cannot fit the current data for any amount of reionization, and even scale-invariant models must have an optical depth to last scattering of below 0.3. For the currently-favoured low-density model with Ω0=0.3\Omega_0 = 0.3 and a cosmological constant, the earliest reionization permitted to occur is at around redshift 35, which roughly coincides with the highest estimate in the literature. We provide general fitting functions for the maximum permitted optical depth, as a function of cosmological parameters. We do not consider the inclusion of tensor perturbations, but if present they would strengthen the upper limits we quote.Comment: 9 pages LaTeX file with ten figures incorporated (uses mn.sty and epsf). Corrects some equation typos, superseding published versio

    Kaons and antikaons in hot and dense hadronic matter

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    Abstract: The medium modification of kaon and antikaon masses, compatible with low energy KN scattering data, are studied in a chiral SU(3) model. The mutual interactions with baryons in hot hadronic matter and the e ects from the baryonic Dirac sea on the K( ¯K ) masses are examined. The in-medium masses from the chiral SU(3) e ective model are compared to those from chiral perturbation theory. Furthermore, the influence of these in-medium e ects on kaon rapidity distributions and transverse energy spectra as well as the K, ¯K flow pattern in heavy-ion collision experiments at 1.5 to 2 A·GeV are investigated within the HSD transport approach. Detailed predictions on the transverse momentum and rapidity dependence of directed flow v1 and the elliptic flow v2 are provided for Ni+Ni at 1.93 A·GeV within the various models, that can be used to determine the in-medium K± properties from the experimental side in the near future

    Recruitment of RNA polymerase III to its target promoters

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    A key step in retrieving the information stored in the complex genomes of eukaryotes involves the identification of transcription units and, more specifically, the recognition of promoter sequences by RNA polymerase. In eukaryotes, the task of recognizing nuclear gene promoters and then transcribing the genes is divided among three highly related enzymes, RNA polymerases I, II, and III. Each of these RNA polymerases is dedicated to the transcription of specific sets of genes, and each depends on accessory factors, the so-called transcription factors, to recognize its cognate promoter sequences

    Is AGN feedback necessary to form red elliptical galaxies?

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    We have used GADGET2 to simulate the formation of an elliptical galaxy in a cosmological dark matter halo with mass 3x10^12M_Sun/h. Using a stellar population synthesis model has allowed us to compute magnitudes, colours and surface brightness profiles. We have included a model to follow the growth of a central black hole and we have compared the results of simulations with and without feedback from AGNs. We have studied the interplay between cold gas accretion and merging in the development of galactic morphologies, the link between colour and morphology evolution, the effect of AGN feedback on the photometry of early type galaxies, the redshift evolution in the properties of quasar hosts, and the impact of AGN winds on the chemical enrichment of the intergalactic medium (IGM). We have found that the early phases of galaxy formation are driven by the accretion of cold filamentary flows, which form a disc at the centre of the dark matter halo. When the dark matter halo is sufficiently massive to support the propagation of a stable shock, cold accretion is shut down, and the star formation rate begins to decline. Mergers transform the disc into an elliptical galaxy, but also bring gas into the galaxy. Without a mechanism that removes gas from the merger remnants, the galaxy ends up with blue colours, atypical for its elliptical morphology. AGN feedback can solve this problem even with a fairly low heating efficiency. We have also demonstrated that AGN winds are potentially important for the metal enrichment of the IGM a high redshift.(abridged)Comment: 19 pages and 17 figures, accepted to MNRAS ID: MN-07-1954-MJ.R1 . For high resolution images please check following link: http://www.aip.de/People/AKhalatyan/COSMOLOGY/BHCOSMO

    Stochastic evolutions in superspace and superconformal field theory

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    Some stochastic evolutions of conformal maps can be described by SLE and may be linked to conformal field theory via stochastic differential equations and singular vectors in highest-weight modules of the Virasoro algebra. Here we discuss how this may be extended to superconformal maps of N=1 superspace with links to superconformal field theory and singular vectors of the N=1 superconformal algebra in the Neveu-Schwarz sector.Comment: 13 pages, LaTe

    Critical Review Of Quark Gluon Plasma Signals

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    Compelling evidence for a new form of matter has been claimed to be formed in Pb+Pb collisions at SPS. We critically review two suggested signatures for this new state of matter: First the suppression of the J/Ψ\Psi, which should be strongly suppressed in the QGP by two different mechanisms, the color-screening and the QCD-photoeffect. Secondly the measured particle, in particular strange hadronic, ratios might signal the freeze-out from a quark-gluon phase.Comment: 7 pages 6 figures, Contribution to the Proceedings of CRIS 2000, 3rd Catania Relativistic Ion Studies, Acicastello, Italy, May 22-26, 200

    The Development of Ethel Wilson's Swamp Angel: An Assessment of the Current State of Knowledge and Areas for Future Research

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    This project analyzes the development of Ethel Wilson’s Swamp Angel and assesses the ways in which a future critical edition of the novel could be more comprehensive than previously published editions. The history of this canonical Canadian novel has been left mostly unexplored and may have been intentionally concealed in some published editions. By inspecting archival materials, including Wilson’s correspondence, I examine how Wilson’s relationships with her editors influenced the different published versions of the novel, which feature two different endings to the story. This paper considers how Wilson’s friendship with John Gray, her editor at Macmillan, may have helped to produce a more poetic and Modernist version of the book in the original Canadian edition than in the American edition published by Harper, which were simultaneously published in 1954. The project also considers how some of Wilson’s publishers may have prioritized lower printing costs or convenience over publishing what they deemed to be the better version of the novel. Additionally, by examining Wilson’s manuscript, I discover that more than four different versions to the end of Wilson’s novel may have existed, as opposed to just two. Having studied ten versions of Wilson’s novel first-hand and the secondary resources most relevant to the development of Swamp Angel, such as the critical edition of the novel by Li-Ping Geng and the critical biography of Ethel Wilson by David Stouck, I suggest how a future critical edition of the novel could be more useful to scholars and more descriptive regarding the novel’s evolution

    Innovation Technology

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    Comprise definition of 1500 terms. Innovation from A to Z presents a glossary, including: Terms, older terms whose meanings have changed, acronyms, synonyms, famous names, selected abbreviations, and cross-references. A highly interdisciplinary approach incorporating strategy and entrepreneurship with technology and engineering sciences, economics, marketing, organizational behavior and theory. Ideal for engineers, managers, sales people and economists. Innovation Technology from A to Z Glossary of terms, including acronyms, synonyms, abbreviations, cross-references 1500 terms supplemented by figures and tables that clearly demonstrate the state-of-the-art in Innovation Technolog

    Stochastic Metallic-Glass Cellular Structures Exhibiting Benchmark Strength

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    By identifying the key characteristic “structural scales” that dictate the resistance of a porous metallic glass against buckling and fracture, stochastic highly porous metallic-glass structures are designed capable of yielding plastically and inheriting the high plastic yield strength of the amorphous metal. The strengths attainable by the present foams appear to equal or exceed those by highly engineered metal foams such as Ti-6Al-4V or ferrous-metal foams at comparable levels of porosity, placing the present metallic-glass foams among the strongest foams known to date
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