5,225 research outputs found

    Are speed enforcement cameras more effective than other speed management measures? The impact of speed management schemes on 30mph roads.

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    This paper presents the results of an evaluation of the impact of various types of speed management schemes on both traffic speeds and accidents. The study controls for general trends in accidents, regression-to-mean effects and migration, separately estimating the accident changes attributable to the impact of the schemes on traffic speed and on traffic volume. It was found that, when judged in absolute terms, all types of speed management scheme have remarkably similar effects on accidents, with an average fall in personal injury accidents of about 1 accident/km/year. In terms of the percentage accident reduction, however, engineering schemes incorporating vertical deflections (such as speed humps or cushions) offer the largest benefits: at 44%, the average reduction in personal injury accidents attributable to such schemes, is twice that at sites where safety cameras were used to control speeds (22%) and they were the only type of scheme to have a significant impact on fatal and serious accidents. Other types of engineering scheme (with a fall of 29% in personal injury accidents) were on average less effective in reducing accidents than schemes with vertical features but more effective than cameras. All types of scheme were generally effective in reducing speeds, with the largest reductions tending to be obtained with vertical deflections and the smallest with other types of engineering schemes

    Commuting charges and symmetric spaces

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    Every classical sigma-model with target space a compact symmetric space G/HG/H (with GG classical) is shown to possess infinitely many local, commuting, conserved charges which can be written in closed form. The spins of these charges run over a characteristic set of values, playing the role of exponents of G/HG/H, and repeating modulo an integer hh which plays the role of a Coxeter number.Comment: LaTeX, 16 pages; v2: footnote adde

    Conserved Charges and Supersymmetry in Principal Chiral Models

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    We report on investigations of local (and non-local) charges in bosonic and supersymmetric principal chiral models in 1+1 dimensions. In the bosonic PCM there is a classically conserved local charge for each symmetric invariant tensor of the underlying group. These all commute with the non-local Yangian charges. The algebra of the local charges amongst themselves is rather more subtle. We give a universal formula for infinite sets of mutually commuting local charges with spins equal to the exponents of the underlying classical algebra modulo its Coxeter number. Many of these results extend to the supersymmetric PCM, but with local conserved charges associated with antisymmetric invariants in the Lie algebra. We comment briefly on the quantum conservation of local charges in both the bosonic and super PCMs.Comment: 18 pages, LaTeX. Revised and up-dated version based on conference talks by JME and NJ

    Electronic Medical Record in the Simulation Hospital: Does It Improve Accuracy in Charting Vital Signs, Intake, and Output?

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    The introduction of electronic health records has created a shift in the way nursing care is delivered (McBride, Delaney, & Tietze, 2012; Furukawa, Raghu, & Shao, 2010). A factor which heavily influences a nurse’s ability to navigate and utilize EMR is adequate education in the use of computerized documentation (McBride, et al., 2012). There is an increased risk for error at the bedside without the correct knowledge and skills regarding EMR documentation (Kelly, Brandon, & Docherty, 2011). This skill should be introduced during the pre-licensure education of the nurse. Two groups of associate degree nursing students attending a small community college in Northern California were examined to determine if introduction of EMR in the simulation hospital increased accuracy in documenting vital signs, intake, and output. The first group of students charted using paper- pencil during simulation; the second group used an academic EMR. Each group was evaluated during their preceptor rotation at two local inpatient facilities. Registered nurse preceptors provided information by responding to a 10 question survey regarding the use of student EMR documentation during the 120 hour preceptor rotation. The implementation of the EMR into the simulation hospital, although a complex undertaking, provided students a safe environment in which to practice using technology and receive feedback from faculty regarding accurate documentation

    The Psychological Impact of Investigating Crime Scenes

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    The goal of this study was to determine if there are stressful or psychological impacts from investigating crime scenes. This was accomplished by analyzing ninety-four anonymous surveys that had been distributed to various law enforcement agencies across the country. The surveys asked professional crime scene processors various questions about their careers, home life, and wellbeing. IBM SPSS Statistics was used to analyze questions about physical health, mental health, job position, duties, schedule, and crimes investigated. The surveys were thirty-seven questions each, with several having multiple answer options. The study found the majority of participants did not have any diagnosed disorders but did desire to either quit or retire due to impact on family life or from repeated exposure to tragic violence. Most agencies offer some type of post-crime counseling, but the bulk of participants did not utilize this resource. However, the vast majority of participants did think that counseling would be helpful and favored having the option in their career field

    Invariant tensors and Casimir operators for simple compact Lie groups

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    The Casimir operators of a Lie algebra are in one-to-one correspondence with the symmetric invariant tensors of the algebra. There is an infinite family of Casimir operators whose members are expressible in terms of a number of primitive Casimirs equal to the rank of the underlying group. A systematic derivation is presented of a complete set of identities expressing non-primitive symmetric tensors in terms of primitive tensors. Several examples are given including an application to an exceptional Lie algebra.Comment: 11 pages, LaTeX, minor changes, version in J. Math. Phy

    Enhanced star formation: The importance of bars in spiral galaxies

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    It was found that among an IR luminous subset of nearby spiral galaxies, nearly all of the systems with IRAS colors and luminosities indicative of enhanced star formation are barred. Radio continuum and IR spectroscopic results support the hypothesis that this emission originates within the central 2 kpc; possibly in a circumnuclear ring. It was also found that outer rings are over represented among these barred systems and suggest possible reasons for this phenomena

    Databases and Inter-Connectivity in Ground-Based Astronomy

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    Optical and infrared ground-based astronomy is undergoing a renaissance. Advances in material technology, system modeling, and the ability to correct atmospheric distortions in real time have produced a new generation of powerful, large telescopes. An equally profound revolution stems from the availability of large observational databases that span the electromagnetic spectrum. The increased use of such databases as well as the need to operate the new telescopes efficiently requires the development of a National or International Virtual Observatory to set standards for astronomical database formats, data quality assurance, and access protocols, and also to provide all-inclusive centers for data products

    A Global Photometric Analysis of 2MASS Calibration Data

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    We present results from the application of a global photometric calibration (GPC) procedure to calibration data from the first 2 years of The Two Micron All Sky Survey (2MASS). The GPC algorithm uses photometry of both primary standards and moderately bright `tracer' stars in 35 2MASS calibration fields. During the first two years of the Survey, each standard was observed on approximately 50 nights, with about 900 individual measurements. Based on the photometry of primary standard stars and secondary tracer stars and under the assumption that the nightly zeropoint drift is linear, GPC ties together all calibration fields and all survey nights simultaneously, producing a globally optimized solution. Calibration solutions for the Northern and Southern hemisphere observatories are found separately, and are tested for global consistency based on common fields near the celestial equator. Several results from the GPC are presented, including establishing candidate secondary standards, monitoring of near-infrared atmospheric extinction coefficients, and verification of global validity of the standards. The solution gives long-term averages of the atmospheric extinction coefficients, A_J=0.096, A_H=0.026, A_{K_s}=0.066 (North) and A_J=0.092, A_H=0.031, A_{K_s}=0.065 (South), with formal error of 0.001. The residuals show small seasonal variations, most likely due to changing atmospheric content of water vapor. Extension of the GPC to approximately 100 field stars in each of the 35 calibration fields yields a catalog of more than two thousand photometric standards ranging from 10th to 14th magnitude, with photometry that is globally consistent to ∼1\sim 1%.Comment: 19 pages, 10 figures; Submitted to AJ. The table of secondary standards is available from ftp://nova.astro.umass.edu/pub/nikolaev/ or ftp://anon-ftp.ipac.caltech.edu/pub/2mass/globalcal
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