43 research outputs found

    Simulated Optimisation of Disordered Structures with negative Poisson’s ratios

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    Copyright © 2009 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Mechanics of Materials. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Mechanics of Materials, Vol. 41 Issue 8 (2009). DOI: 10.1016/j.mechmat.2009.04.008Two-dimensional regular theoretical units that give a negative Poisson’s ratio (NPR) are well documented and well understood. Predicted mechanical properties resulting from these models are reasonably accurate in two dimensions but fall down when used for heterogeneous real-world materials. Manufacturing processes are seldom perfect and some measure of heterogeneity is therefore required to account for the deviations from the regular unit cells in this real-life situation. Analysis of heterogeneous materials in three dimensions is a formidable problem; we must first understand heterogeneity in two dimensions. This paper approaches the problem of finding a link between heterogeneous networks and its material properties from a new angle. Existing optimisation tools are used to create random two-dimensional topologies that display NPR, and the disorder in the structure and its relationship with NPR is investigated

    Lung adenocarcinoma promotion by air pollutants

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    A complete understanding of how exposure to environmental substances promotes cancer formation is lacking. More than 70 years ago, tumorigenesis was proposed to occur in a two-step process: an initiating step that induces mutations in healthy cells, followed by a promoter step that triggers cancer development1. Here we propose that environmental particulate matter measuring ≤2.5 μm (PM2.5), known to be associated with lung cancer risk, promotes lung cancer by acting on cells that harbour pre-existing oncogenic mutations in healthy lung tissue. Focusing on EGFR-driven lung cancer, which is more common in never-smokers or light smokers, we found a significant association between PM2.5 levels and the incidence of lung cancer for 32,957 EGFR-driven lung cancer cases in four within-country cohorts. Functional mouse models revealed that air pollutants cause an influx of macrophages into the lung and release of interleukin-1β. This process results in a progenitor-like cell state within EGFR mutant lung alveolar type II epithelial cells that fuels tumorigenesis. Ultradeep mutational profiling of histologically normal lung tissue from 295 individuals across 3 clinical cohorts revealed oncogenic EGFR and KRAS driver mutations in 18% and 53% of healthy tissue samples, respectively. These findings collectively support a tumour-promoting role for PM2.5 air pollutants and provide impetus for public health policy initiatives to address air pollution to reduce disease burden

    Demonstration of the United States Road Assessment (usRAP) as a Systematic Safety Tool for Two Lane Roadways and Highways in Kansas

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    The United States Road Assessment Program (usRAP) is a systematic tool that determines areas of risk based on roadways characteristics. To determine the effectiveness of the usRAP tool, three rural two-lane corridors, a US highway, a Kansas highway, and a rural secondary road, were selected for this study. Data collection for the usRAP software included manual speed data collection, system-wide centerline miles and crashes, crash costs, countermeasure costs, and manual roadway coding data every 100 m. The usRAP software evaluated and developed a star rating and a Safer Roads Investment Plan for each corridor

    Demonstration of the United States Road Assessment (usRAP) as a Systematic Safety Tool for Two Lane Roadways and Highways in Kansas

    Get PDF
    The United States Road Assessment Program (usRAP) is a systematic tool that determines areas of risk based on roadways characteristics. To determine the effectiveness of the usRAP tool, three rural two-lane corridors, a US highway, a Kansas highway, and a rural secondary road, were selected for this study. Data collection for the usRAP software included manual speed data collection, system- wide centerline miles and crashes, crash costs, countermeasure costs, and manual roadway coding data every 100 m. The usRAP software evaluated and developed a star rating and a Safer Roads Investment Plan for each corridor
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