11,047 research outputs found

    Simultaneous measurements of particulate and gas-phase water-soluble organic carbon concentrations at remote and urban-influenced locations

    Get PDF
    The sources, sinks, and overall importance of watersoluble organic carbon (WSOC) in the atmosphere are not well understood. Although the primary historical focus has been on particulate WSOC (WSOCP), here we also present results obtained using a newly developed technique that additionally measures gas-phase water-soluble organic carbon (WSOCG). These first-of-their-kind measurements show that WSOCG can often be more than ten times larger than WSOCP at both urban and remote locations. The average fraction of WSOC residing in the gas phase (fg = WSOCG/(WSOCG + WSOCP)) at five various field sites ranged from 0.64 to 0.93, implying significant differences in WSOC phase partitioning between locations. At Houston, TX, and Summit, Greenland, a repeatable diurnal pattern was observed, with minimum values for fg occurring at night. These trends likely are due, at least in part, to temperature and/or relative humidity related gas-to-particle partitioning. These coincident measurements of WSOC in both the gas and particle phases indicate that a relatively large reservoir of water-soluble organic mass is not taken into account by measurements focused only on WSOCP. In addition, a significant amount of WSOCG is available to form WSOCP or enter cloud droplets depending on the chemical and physical properties of the droplets and/or aerosols present. Citation: Anderson, C., J. E. Dibb, R. J. Griffin, and M. H. Bergin (2008), Simultaneous measurements of particulate and gas-phase water-soluble organic carbon concentrations at remote and urban-influenced locations, Geophys. Res. Lett., 35, L13706, doi:10.1029/2008GL033966

    Comparative study of turbulence models in predicting hypersonic inlet flows

    Get PDF
    A numerical study was conducted to analyze the performance of different turbulence models when applied to the hypersonic NASA P8 inlet. Computational results from the PARC2D code, which solves the full two-dimensional Reynolds-averaged Navier-Stokes equation, were compared with experimental data. The zero-equation models considered for the study were the Baldwin-Lomax model, the Thomas model, and a combination of the Baldwin-Lomax and Thomas models; the two-equation models considered were the Chien model, the Speziale model (both low Reynolds number), and the Launder and Spalding model (high Reynolds number). The Thomas model performed best among the zero-equation models, and predicted good pressure distributions. The Chien and Speziale models compared very well with the experimental data, and performed better than the Thomas model near the walls

    Formative Assessment of Academic Writing with English Learners in an Algebra Class

    Get PDF
    A case study of five English learners examined students’ writing in a co-taught high school math class. The goal of the study was to investigate how two different types of writing activities impacted students’ understanding of mathematical concepts. A writing rubric was used to measure student writing, and the researcher complied in-class tests. The scores on the writing samples were compared to students’ test results to look for trends in the data. Results of the case study were limited in their ability to identify a direct connection with the writing strategies and students’ test results, but the case study revealed how student writing improved over the school year and highlighted some of the distinctions among different groups of English learners

    Sunday in the Shop with Rob

    Get PDF
    On February 21st, 2019, Southern Illinois University Department of Theater produce

    Workshop - Amundsen Sea Embayment Tectonic and Glacial History - Programme and Abstracts

    Get PDF
    Overall Objective: Review existing data and identify priorities for future geoscience research (terrestrial, marine and airborne) in the Amundsen Sea embayment (ASE) region required to develop a better understanding of the past, present and future behaviour of this sector of the West Antarctic Ice Sheet (WAIS). Background: The ASE is the most rapidly changing sector of the WAIS and contains enough ice to raise global sea level by 1.2 m. Over the past few years considerable efforts have been made to acquire new data to improve knowledge of the geological structure, subglacial topography, continental shelf bathymetry and glacial history of this remote region. In this workshop we aim to review the current state of knowledge on the tectonic and glacial evolution of the Amundsen Sea embayment. Particular emphasis will be placed on work that will improve boundary conditions for ice sheet models (e.g. subglacial topography, shelf bathymetry, palaeotopography, heat flow and substrate types) and provide palaeo-data against which model outputs can be compared. There will also be a focus on plans and targets for future scientific drilling that will reveal the history of this sector of the WAIS and its sensitivity to major climate changes

    Preferences for Residential Development Attributes and Support for the Policy Process: Implications for Management and Conservation of Rural Landscapes

    Get PDF
    The rural public may not only be concerned with the consequences of land management; residents may also have systematic preferences for policy instruments applied to management goals. Preferences for outcomes do not necessarily imply matching support for the underlying policy process. This study assesses relationships among support for elements of the policy process and preferences for management outcomes. Preferences are examined within the context of alternative proposals to manage growth and conserve landscape attributes in southern New England. Results are based on (a) stated preferences estimated from a multi-attribute contingent choice survey of rural residents, and (b) Likert-scale assessment of strength of support for land use policy tools. Findings indicate general but not universal correlation among policy support indicators and preferences for associated land use outcomes, but also confirm the suspicion that policy support and land use preference may not always coincide.Agricultural and Food Policy,

    Shoreline Erosion in Tidewater Virginia

    Get PDF

    Towards a Comprehensive Approach to Clinical Education: A Response to the New Reality

    Get PDF
    In this Article, we describe one model through which the process could be initiated and the results evaluated within the economic and educational structure of the contemporary university law school
    • …
    corecore