1,451 research outputs found

    Lightweight reflector assembly

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    An inexpensive, lightweight reflective assembly member having good optical quality and particularly adaptable to accommodating temperature variations without providing destructive thermal stresses and reflective slope errors is described. The reflective assembly consists of a thin sheet of glass with appropriate reflective coating and a cellular glass block substrate bonded together. The method of fabrication includes abrading the cellular substrate with an abrasive master die to form an appropriate concave surface. An adhesive is applied to the abraded surface and a lamina reflective surface is placed under a uniform pressure to conform the reflective surface onto the desired abraded surface of the substrate

    Deepening Democracy: Inclusion, Deliberation, And Voice In The Grassroots South

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    Through an exploration of grassroots challenges to shallow democracy in South Carolina, this dissertation offers a model of democratization based on inclusion, deliberation, and empowerment as a remedy for democratic insufficiency. I posit that greater emphasis on inclusive democratic deliberation, both inside and outside formal political structures, will help deepen the South’s shallow democracy, and that inclusive deliberation fostered through grassroots organizing that priorities consciousness raising, empowerment, and activism training will positively affect participants, deliberation, and policy outcomes. Taking a grounded theory approach, I consider case studies of three organizations based in Columbia, South Carolina, and their attending theories of democratization: The Modjeska Simkins School for Human Rights (democratization through education); Tell Them (democratization through praxis); and Girls Rock Columbia (democratization through affirmation). The experiences of these organizations offer insights into how relatively small, locally-based organizations can deepen democracy by vii confronting traditional barriers to inclusive democratic deliberation. Through education, praxis, and affirmation, these groups give politically underrepresented people the tools they need to become self-advocates. More importantly, through consciousness raising and empowerment, the organizations lend a sense of authority to the potentially powerless. Finally, by imbuing participants with feelings of agency and authority, the organizations work to create a more representative, comprehensive body for future democratic deliberations. Individuals who are able (and willing) to advocate for themselves enhance the quality of democracy at each level of government, as well as in the nongovernmental aspects of their day-to-day lives. The inclusive grassroots work that the Modjeska Simkins School, Tell Them, and Girls Rock do is directly in support of this. Each of the democratic elements I consider here (inclusion, deliberation, and voice) benefit from the incorporation of the other two. Ultimately, I find that a meaningfully deepened democracy requires inclusive deliberation that lifts up and empowers the quiet voices

    Application of surrogate methods for assessing the bioavailability of PAHs in sediments to a sediment ingesting bivalve

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    The usefulness of two surrogate methods for rapidly determining the bioavailability of PAHs in hydrocarbon-contaminated marine sediments was assessed. Comparisons are made between the PAHs accumulated by the benthic bivalve, Tellina deltoidalis, and the extractable-PAHs determined using a 6-h XAD-2 resin desorption method and a 4-h gut fluid mimic (GFM) extraction method. There were significant positive relationships between PAH bioaccumulation by the bivalves and sediment PAH concentrations. These relationships were not improved by normalising the sediment PAH concentrations to the organic carbon concentration. The average percentage lipid content of the bivalves was 1.47 ± 0.22% and BSAFs for total-PAHs ranged from 0.06 to 0.80 (kg OC/kg lipid). The XAD-2 and GFM methods both extracted varying amounts of PAHs from the sediments. Low concentrations of PAHs were extracted by the GFM method (0.2–3.6% of total-PAHs in sediments) and the GFM results were inadequate for generalising about the bioavailability of the PAHs in the sediments. The XAD-2 method extracted greater amounts of PAHs (3–34% of total-PAHs in sediments), however, the total-PAH concentrations in the sediments provided a better, or equally good, prediction of PAH bioaccumulation by T. deltoidalis. The results indicated that these methods required further development before they can be applied routinely as surrogate methods for assessing the bioavailability of PAHs in sediments. Future research should be directed towards lowering detection limits and obtaining comparative data for a greater range of sediment types, contaminant classes and concentrations, and organisms of different feeding guilds and with different gut chemistry

    Making A Difference: Year Two Report of the Pennsylvania High School Coaching Initiative

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    This report examines the implementation of the second year of three for the Pennsylvania High School Coaching Initiative (PAHSCI). Funded by the Annenberg Foundation, this initiative focuses on literacy and math coaches providing support to teachers from across the major subject areas to create literacy-rich classrooms in which students actively engage in learning tasks that deepen their content knowledge and strengthen their abilities to think critically and communicate well. This report presents findings from the first two years of research. It includes survey research as well as in-depth qualitative research in participating schools and districts and provides recommendations for PAHSCI stakeholders as they refine the program and for other education reformers as they consider the benefits of instructional coaching as a strategy for improving high schools and student achievement

    Processes controlling metal transport and retention as metal-contaminated groundwaters efflux through estuarine sediments

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    Factors affecting the transport and retention of Cd, Cr, Cu, Ni, Pb and Zn in acidic groundwaters as they pass through estuarine sediments were investigated using column experiments. Acidic groundwaters caused the rapid dissolution of iron sulfide (AVS) and other iron and manganese phases from sediments that are important for metal binding and buffering. Metal breakthrough to overlying water occurred in the order of Ni\u3eZn\u3eCd\u3e\u3eCu\u3e\u3eCr/Pb. Metal transport increased as the sediment permeability increased, reflecting the low resistance to flow caused by larger sand-sized particles and the decreased abundance of metal adsorption sites on these materials. Metal mobility increased as the groundwater pH decreased, as flow rate or metal concentrations increased, and as the exposure duration increased. Groundwater Cr and Pb were promptly attenuated by the sediments, the mobility of Cu was low and decreased rapidly as sediment pH increased above 4.5, while Cd, Ni and Zn were the most easily transported to the surface sediments and released to the overlying waters. For groundwaters of pH 3, metal migration velocities through sandy sediments were generally 0.5-2% (Cr, Pb), 1-6% (Cu) and 4-13% (Cd, Ni, Zn) of the total groundwater velocity (9-700 m/year). The oxidative precipitation of Fe(II) and Mn(II) in the groundwaters did not affect metal mobility through the sediments. The results indicated that the efflux of acidic and metal-contaminated groundwater through estuarine sediments would affect organisms resident in sandy sediments more greatly than organisms resident in fine-grained, silty, sediments

    The use of immobilised metal affinity chromatography (IMAC) to compare expression of copper-binding proteins in control and copper-exposed marine microalgae

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    Toxicity of metals to aquatic organisms is dependent on both external factors, such as exposure concentration and water quality parameters, and intracellular processes including specific metal-binding sites and detoxification. Current models used to predict copper toxicity in microalgae do not adequately consider these intracellular processes. This study compared the copper-binding proteins from four species of marine microalgae, Dunaliella tertiolecta, Tetraselmis sp., Phaedactylum tricornutum and Ceratoneis closterium, in controls (no added copper) and following a 72-h exposure to copper (sufficient to inhibit growth by approximately 50 %). Cells were lysed by sonication, which was optimised to obtain 54–94 % cell rupture for the different algae. Cell lysates were processed by immobilised metal affinity chromatography (IMAC) using Cu2+ as the bound metal (i.e. Cu-IMAC). Bound proteins were subsequently analysed by SDS-PAGE, comparing proteins recovered from algae that were exposed to copper versus untreated control cells. Individual proteins for which copper exposure resulted in changes to proteins present were excised from gels and further analysed by nano LC ESI-MS/MS; proteins were identified using the Mascot database. Proteins identified in this way included heat-shock proteins, rubisco, α- and β-tubulins and ATP synthase (β subunit). The results established that Cu-IMAC is a useful approach to identify proteins involved in copper binding in algae. This study identified several proteins that may play an active role in responses to copper toxicity in marine microalgae
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