1,220 research outputs found

    ExpoSE:practical symbolic execution of standalone JavaScript

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    JavaScript has evolved into a versatile ecosystem for not just the web, but also a wide range of server-side and client-side applications. With this increased scope, the potential impact of bugs increases. We introduce ExpoSE, a dynamic symbolic execution engine for Node.js applications. ExpoSE automatically generates test cases to find bugs and cover as many paths in the target program as possible. We discuss the specific challenges for symbolic execution arising from the widespread use of regular expressions in such applications. In particular, we make explicit the issues of capture groups, backreferences, and greediness in JavaScript's flavor of regular expressions, and our models improve over previous work that only partially addressed these. We evaluate ExpoSE on three popular JavaScript libraries that make heavy use of regular expressions, and we report a previously unknown bug in the Minimist library

    Accuracy of screening tools for Pap smears in general practice

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    Background: Data extraction tools (DETs) are increasingly being used for research and audit of general practice, despite their limitations. Objective: This study explores the accuracy of Pap smear rates obtained with a DET compared to that of the Pap smear rate obtained with a manual file audit. Method: A widely available DET was used to establish the rate of Pap smears in a large multi-general practice (multi-GP) in regional New South Wales followed by a manual audit of patient files. The main outcome measure was identification of possible discrepancies between the rates established. Results: The DET used significantly underestimated the level of cervical screening compared to the manual audit. In some instances, the patient file contained phone/specialist record of Pap smear conducted elsewhere, which accounted for the failure of the DET to detect some smears. Those patients who had Pap smears whose pathology codes differed between time intervals, i.e. from different pathology providers or from within the same provider but using a different code, were less likely to have had their most recent Pap smear detected by the DET (p \u3c 0.001). Conclusion: Data obtained from DETs should be used with caution as they may not accurately reflect the rate of Pap smears from electronic medical records

    Call for Australia to head back into space

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    The Collapse Behavior of Compacted West Tennessee Loess

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    This thesis is an investigation of the collapse behavior of two types of compacted loessial soil. Different stress paths will be followed to define the collapse behavior due to changes in net vertical stress and matric suction for loess specimens acquired from two locations in West Tennessee. The two loessial soils chosen have different grain size distributions, which result in differences in soil structure which should impact the collapsibility of the soil. The soil-water characteristic curve will be measured for the soils in the non-collapsed and collapsed conditions. The volume change behavior will be evaluated using results of collapse tests, measured soil-water characteristic curves, unsaturated soil mechanics volume change theory, and related references. The differences in the test results between the two soil types will be interpreted in light of the differences in grain size distributions. Recommendations for future research on collapsibility will also be presented

    The WiggleZ Dark Energy Survey: Survey Design and First Data Release

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    The WiggleZ Dark Energy Survey is a survey of 240,000 emission line galaxies in the distant universe, measured with the AAOmega spectrograph on the 3.9-m Anglo-Australian Telescope (AAT). The target galaxies are selected using ultraviolet photometry from the GALEX satellite, with a flux limit of NUV<22.8 mag. The redshift range containing 90% of the galaxies is 0.2<z<1.0. The primary aim of the survey is to precisely measure the scale of baryon acoustic oscillations (BAO) imprinted on the spatial distribution of these galaxies at look-back times of 4-8 Gyrs. Detailed forecasts indicate the survey will measure the BAO scale to better than 2% and the tangential and radial acoustic wave scales to approximately 3% and 5%, respectively. This paper provides a detailed description of the survey and its design, as well as the spectroscopic observations, data reduction, and redshift measurement techniques employed. It also presents an analysis of the properties of the target galaxies, including emission line diagnostics which show that they are mostly extreme starburst galaxies, and Hubble Space Telescope images, which show they contain a high fraction of interacting or distorted systems. In conjunction with this paper, we make a public data release of data for the first 100,000 galaxies measured for the project.Comment: Accepted by MNRAS; this has some figures in low resolution format. Full resolution PDF version (7MB) available at http://www.physics.uq.edu.au/people/mjd/pub/wigglez1.pdf The WiggleZ home page is at http://wigglez.swin.edu.au

    Nucleosynthesis-relevant conditions in neutrino-driven supernova outflows. II. The reverse shock in two-dimensional simulations

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    After the initiation of the explosion of core-collapse supernovae, neutrinos emitted from the nascent neutron star drive a supersonic baryonic outflow. This neutrino-driven wind interacts with the more slowly moving, earlier supernova ejecta forming a wind termination shock (or reverse shock), which changes the local wind conditions and their evolution. Important nucleosynthesis processes (alpha-process, charged-particle reactions, r-process, and vp-process) occur or might occur in this environment. The nucleosynthesis depends on the long-time evolution of density, temperature, and expansion velocity. Here we present two-dimensional hydrodynamical simulations with an approximate description of neutrino-transport effects, which for the first time follow the post-bounce accretion, onset of the explosion, wind formation, and the wind expansion through the collision with the preceding supernova ejecta. Our results demonstrate that the anisotropic ejecta distribution has a great impact on the position of the reverse shock, the wind profile, and the long-time evolution. This suggests that hydrodynamic instabilities after core bounce and the consequential asymmetries may have important effects on the nucleosynthesis-relevant conditions in the neutrino-heated baryonic mass flow from proto-neutron stars.Comment: 13 pages, 8 figures, accepted for publication in A&
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