38,985 research outputs found

    Study to determine an improved method for Apollo propellant system decontamination and propellant tank drying Summary report

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    Vapor phase cleaning method for Apollo propellant system decontamination and propellant tank dryin

    Direct comparison of cross-sectional scanning capacitance microscope dopant profile and vertical secondary ion-mass spectroscopy profile

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    Journal ArticleThe scanning capacitance microscope (SCM) has been shown to be useful for quantitative 2D dopant profiling near the surface of silicon. An atomic force microscope is used to position a nanometer scale tip at a silicon surface, and local capacitance change is measured as a function of sample bias. A new feedback method has been recently demonstrated in which the magnitude of the ac bias voltage applied to the sample is adjusted to maintain a constant capacitance change as the tip is scanned across the sample surface

    Alfred Russel Wallace Notes 11: Wallace, Darwin, Education, & the Class Question

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    In a recent paper by John van Wyhe (2020), the issue of class was discussed and whether Wallace came from a “working class” background. As a result of class differences could or should Wallace be considered differently from Darwin, who supposedly came from a higher class? An additional “myth” highlighted was whether Wallace left school, aged 14, due to difficult family financial circumstances. Van Wyhe contends that Darwin and Wallace were both middle class, and Wallace left school at the “normal” school-leaving age. This article shows that both contentions are mistaken. Class in the 19th century was complex and difficult, indeed a developing concept. The idea of a “middle class” was new and within this there was a stratification between the upper and lower middle classes. As for schools and education, there was no set leaving age specified and education was usually determined by class and family finance

    Prospects for reduced energy transports: A preliminary analysis

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    The recent energy crisis and subsequent substantial increase in fuel prices have provided increased incentive to reduce the fuel consumption of civil transport aircraft. At the present time many changes in operational procedures have been introduced to decrease fuel consumption of the existing fleet. In the future, however, it may become desirable or even necessary to introduce new fuel-conservative aircraft designs. This paper reports the results of a preliminary study of new near-term fuel conservative aircraft. A parametric study was made to determine the effects of cruise Mach number and fuel cost on the optimum configuration characteristics and on economic performance. For each design, the wing geometry was optimized to give maximum return on investment at a particular fuel cost. Based on the results of the parametric study, a nominal reduced energy configuration was selected. Compared with existing transport designs, the reduced energy design has a higher aspect ratio wing with lower sweep, and cruises at a lower Mach number. It has about 30% less fuel consumption on a seat-mile basis

    Observational Constraints on Superbubble X-ray Energy Budgets

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    The hot, X-ray-emitting gas in superbubbles imparts energy and enriched material to the interstellar medium (ISM) and generates the hot ionized medium, the ISM's high-temperature component. The evolution of superbubble energy budgets is not well understood, however, and the processes responsible for enhanced X-ray emission in superbubbles remain a matter of debate. We present Chandra ACIS-S observations of two X-ray-bright superbubbles in the Large Magellanic Cloud (LMC), DEM L50 (N186) and DEM L152 (N44), with an emphasis on disentangling the true superbubble X-ray emission from non-related diffuse emission and determining the spatial origin and spectral variation of the X-ray emission. An examination of the superbubble energy budgets shows that on the order of 50% of the X-ray emission comes from regions associated with supernova remnant (SNR) impacts. We find some evidence of mass-loading due to swept-up clouds and metallicity enrichment, but neither mechanism provides a significant contribution to the X-ray luminosities. We also find that one of the superbubbles, DEM L50, is likely not in collisional ionization equilibrium. We compare our observations to the predictions of the standard Weaver et al. model and to 1-D hydrodynamic simulations including cavity supernova impacts on the shell walls. Our observations show that mass-loading due to thermal evaporation from the shell walls and SNR impacts are the dominant source of enhanced X-ray luminosities in superbubbles. These two processes should affect most superbubbles, and their contribution to the X-ray luminosity must be considered when determining the energy available for transport to the ISM.Comment: 25 pages, 11 figures, accepted for publication in Ap

    Making the Digital Humanities More Open

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    BrailleSC will undertake its second stage of development by designing and deploying a WordPress-based accessibility tool that will create braille content for endusers who are blind or low vision. Specifically, we plan to extend the use of Anthologize--a free and open source plug-in for WordPress that currently translates any RSS text into PDF, ePub, HTML, or TEI--to include the conversion of text to braille. As a result, we will not only make it easy for content creators to convert a text into braille, thereby extending humanities content to hundreds of thousands of visually disabled readers, but we will also experiment with making braille available visually through the WordPress interface. In partnership with the Maryland Institute for Technology in the Humanities (MITH) at the University of Maryland, College Park, we will continue to model the ways in which digital humanities projects should be designed and implemented with the needs of disabled users in mind

    Readiness to use physical activity as a smoking cessation aid: a multiple behaviour change application of the Transtheoretical Model among quitters attending Stop Smoking Clinics

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    Objective: Physical activity (PA) reduces cigarette cravings during smoking abstinence. However, little is known about quitters’ use of PA. This study aimed to: (1) determine the extent of quitters’ past and current use of PA as a cessation aid, while attempting to quit; (2) examine the relationship between use of PA and quitter characteristics and cognitions, within the Transtheoretical Model framework. Methods: Self-report surveys were completed by 181 smokers attending Stop Smoking Services in England and Scotland. Results: Twenty-two percent of quitters reported currently using PA to control their smoking, and 35% had used it during a previous quit attempt. Those in a more advanced stage of readiness for using PA as a cessation aid, held more positive beliefs regarding self-efficacy and outcome efficacy. Conclusion: Quitters were more likely to use PA to help them quit when they had greater belief in their own ability to use PA and in the efficacy of PA to help them to quit, and were also meeting weekly PA targets for health. Practice implications: Strategies by stop smoking advisors that aim to enhance client self-efficacy and outcome efficacy beliefs regarding PA as a cessation aid may help to increase the use of this behavioural strategy, since it seems that most quitters do not use PA
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