3,226 research outputs found

    Double-injection, deep-impurity switch development

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    The overall objective of this program is the development of device design and process techniques for the fabrication of a double-injection, deep-impurity (DI)(2) silicon switch that operates in the 1-10 kV range with conduction current of 10 and 1A, respectively. Other major specifications include a holding voltage of 0 to 5 volts at 1 A anode current, 10 microsecond switching time, and power dissipation of 50 W at 75 C. This report describes work that shows how the results obtained at the University of Cincinnati under NASA Grant NSG-3022 have been applied to larger area and higher voltage devices. The investigations include theoretical, analytical, and experimental studies of device design and processing. Methods to introduce deep levels, such as Au diffusion and electron irradiation, have been carried out to "pin down' the Fermi level and control device-switching characteristics. Different anode, cathode, and gate configurations are presented. Techniques to control the surface electric field of planar structures used for (DI)(2) switches are examined. Various sections of this report describe the device design, wafer-processing techniques, and various measurements which include ac and dc characteristics, 4-point probe, and spreading resistance

    Determinants of Formal Giving in Turkey

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    This article shares the results of a recent study on individual giving to civil society organizations in Turkey. Using interview data collected from a random sample of 2,495 Turkish citizens in 2015, we estimate that about 12% to 13% of the Turkish population engage in giving, a relatively low figure compared to international giving. We find that being male, being educated, being satisfied with one’s income, being satisfied with one’s economic circumstances, being a rural resident, as well as one’s level of religiosity, civic activism, and institutional trust are all positively associated with giving in Turkey. Our findings provide a foundation for understanding philanthropic giving in Turkey and contribute to ongoing research about determinants of individual giving across countries

    A comparison of superconductor and manganin technology for electronic links used in space mission applications

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    The electronic link connecting cryogenically cooled radiation detectors to data acquisition and signal processing electronics at higher temperatures contributes significantly to the total heat load on spacecraft cooling systems that use combined mechanical and cryogenic liquid cooling. Using high transition temperature superconductors for this link has been proposed to increase the lifetime of space missions. Herein, several YBCO (YBa2Cu3O7) superconductor-substrate combinations were examined and total heat loads were compared to manganin wire technology in current use. Using numerical solutions to the heat-flow equations, it is shown that replacing manganin technology with YBCO thick film technology can extend a 7-year mission by up to 1 year

    A novel role of Drosophila cytochrome P450-4e3 in permethrin insecticide tolerance

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    The exposure of insects to xenobiotics, such as insecticides, triggers a complex defence response necessary for survival. This response includes the induction of genes that encode key Cytochrome P450 monooxygenase detoxification enzymes. Drosophila melanogaster Malpighian (renal) tubules are critical organs in the detoxification and elimination of these foreign compounds, so the tubule response induced by dietary exposure to the insecticide permethrin was examined. We found that expression of the gene encoding Cytochrome P450-4e3 (Cyp4e3) is significantly up-regulated by Drosophila fed on permethrin and that manipulation of Cyp4e3 levels, specifically in the principal cells of the Malpighian tubules, impacts significantly on the survival of permethrin-fed flies. Both dietary exposure to permethrin and Cyp4e3 knockdown cause a significant elevation of oxidative stress-associated markers in the tubules, including H2O2 and lipid peroxidation byproduct, HNE (4-hydroxynonenal). Thus, Cyp4e3 may play an important role in regulating H2O2 levels in the endoplasmic reticulum (ER) where it resides, and its absence triggers a JAK/STAT and NF-κB-mediated stress response, similar to that observed in cells under ER stress. This work increases our understanding of the molecular mechanisms of insecticide detoxification and provides further evidence of the oxidative stress responses induced by permethrin metabolism

    The determinants of foreign direct investment outflows from the European Union countries.

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    This paper employs a panel econometric model, and takes the horizontal and vertical FDI approach into account in the same empirical specification to scrutinize the determinants of FDI outflows from the selected EU countries at the industry level. We show that both cost related factors and potential demand are important and they mostly significantly affect FDI outflows from these selected EU countries.Foreign Direct Investment; Environmental Sensitivity; European Union Countries.

    Peace by Piece: (Re) imagining Division in Belfast’s Contested Spaces through Memory

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    This paper investigates processes and actions of diversifying memories of division in Northern Ireland’s political conflict known as the Troubles. Societal division is manifested in its built fabric and territories that have been adopted by predominant discourses of a fragmented society in Belfast; the unionist east and the nationalist west. The aim of the paper is to explore current approaches in planning contested spaces that have changed over time, leading to success in many cases. The argument is that divided cities, like Belfast, feature spatial images and memories of division that range from physical, clear-cut segregation to manifested actions of violence and have become influential representations in the community’s associative memory. While promoting notions of ‘re-imaging’ by current councils demonstrates a total erasure of the Troubles through cleansing its local collective memory, there yet remains an attempt to communicate a different tale of the city’s socio-economic past, to elaborate its supremacy for shaping future lived memories. Yet, planning Belfast’s contested areas is still suffering from a poor understanding of the context and its complexity against overambitious visions

    An overview of angiogenesis in bladder cancer

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    Purpose of the review: Angiogenesis plays a key role in bladder cancer (BC) pathogenesis. In the last two decades, increasing number of publications depicting a multitude of novel angiogenic molecules and pathways have emerged. The growing complexity necessitates evaluation of the breadth of current knowledge to highlight key findings and guide future research. Recent findings: Angiogenesis is a dynamic biologic process that is inherently difficult to assess. Clinical assessment of angiogenesis in BCs is advancing with the integration of image analysis systems and dynamic contrast-enhanced and magnetic resonance imaging (DCE-MRI). Tumour associated macrophages (TAMs) significantly influence the angiogenic process and further research is needed to assess their potential as therapeutic targets. A rapidly growing list of non-coding RNAs affect angiogenesis in BCs, partly through modulation of vascular endothelial growth factor (VEGF) activity. Vascular mimicry (VM) has been repeatedly associated with increased tumour aggressiveness in BCs. Standardised assays are needed for appropriate identification and quantification of VM channels. Summary: This article demonstrates the dynamic and complex nature of the angiogenic process and asserts the need for further studies to deepen our understanding
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