22,130 research outputs found

    Hydrogen-fueled engine

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    A hydrogen-oxygen fueled internal combustion engine is described, which utilizes an inert gas, such as argon, as a working fluid to increase the efficiency of the engine, eliminate pollution, and facilitate operation of a closed cycle energy system. In a system where sunlight or other intermittent energy source is available to separate hydrogen and oxygen from water, the oxygen and inert gas are taken into a diesel engine into which hydrogen is injected and ignited. The exhaust is cooled so that it contains only water and the inert gas. The inert gas in the exhaust is returned to the engine for use with fresh oxygen, while the water in the exhaust is returned to the intermittent energy source for reconversion to hydrogen and oxygen

    Searching for annihilation radiation from SN 1006 with SPI on INTEGRAL

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    Historical Type Ia supernovae are a leading candidate for the source of positrons observed through their diffuse annihilation emission in the Galaxy. However, search for annihilation emission from individual Type Ia supernovae has not been possible before the improved sensitivity of \integral. The total 511 keV annihilation flux from individual SNe Ia, as well as their contribution to the overall diffuse emission, depends critically on the escape fraction of positrons produced in 56^{56}Co decays. Late optical light curves suggest that this fraction may be as high as 5%. We searched for positron annihilation radiation from the historical Type Ia supernova SN 1006 using the SPI instrument on \integral. We did not detect significant 511 keV line emission, with a 3σ\sigma flux upper limit of 0.59 x 10−4^{-4} ergs cm^-2 s^-1 for \wsim 1 Msec exposure time, assuming a FWHM of 2.5 keV. This upper limit corresponds to a 7.5% escape fraction, 50% higher than the expected 5% escape scenario, and rules out the possibility that Type Ia supernovae produce all of the positrons in the Galaxy (~ 12% escape fraction), if the mean positron lifetime is less than 105^{5} years. Future observations with \integral will provide stronger limits on the escape fraction of positrons, the mean positron lifetime, and the contribution of Type Ia supernovae to the overall positron content of the Galaxy.Comment: 3 pages, 2 figures, accepted for publication in ApJ

    A Search for Ionized Gas in the Draco and Ursa Minor Dwarf Spheroidal Galaxies

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    The Wisconsin H Alpha Mapper has been used to set the first deep upper limits on the intensity of diffuse H alpha emission from warm ionized gas in the Local Group dwarf spheroidal galaxies (dSphs) Draco and Ursa Minor. Assuming a velocity dispersion of 15 km/s for the ionized gas, we set limits for the H alpha intensity of less or equal to 0.024 Rayleighs and less or equal to 0.021 Rayleighs for the Draco and Ursa Minor dSphs, respectively, averaged over our 1 degree circular beam. Adopting a simple model for the ionized interstellar medium, these limits translate to upper bounds on the mass of ionized gas of approximately less than 10% of the stellar mass, or approximately 10 times the upper limits for the mass of neutral hydrogen. Note that the Draco and Ursa Minor dSphs could contain substantial amounts of interstellar gas, equivalent to all of the gas injected by dying stars since the end of their main star forming episodes more than 8 Gyr in the past, without violating these limits on the mass of ionized gas.Comment: 10 pages, 2 figures, AASTeX two-column format. Accepted for publication in The Astrophysical Journa

    A Significant Threat to Neuropsychological Test Validity

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    Objective: Neuropsychological test security is vital to the validity of assessment. Previous research in our lab has shown that 71% of participants use the Internet to prepare for neuropsychological evaluations (Kimpton, 2015). We investigated the availability of information related to neuropsychological tests on the Internet, a topic that has received little attention in the research literature. Participants and Methods: First, we decided a priori that we would not reveal the terms used in this Internet search, as to not contribute to the problem of threatened test security. We used the Internet search engine “Google” to begin a search using a general question that a person with no neuropsychological expertise would use to access initial results. We obtained 899,000 results for this question. We decided that of these results, we would select from the first five results. One link provided us with a list of 52 commonly used neuropsychological tests. This list also included information about the type of cognitive information that the test was meant to assess. Lastly, we searched for these tests on Google Images and YouTube in order to investigate the extent of the information available. Results: The protocols for 43% of the 52 tests were available on Google Images. At least partial administration demonstrations were available on YouTube for 54% of the 52 neuropsychological tests. These demonstrations revealed the test protocols and basic strategy of the tests. Conclusions: A substantial amount of information regarding neuropsychological tests is available on Google Images and YouTube, threatening the validity of these tests. It is recommended that professional neuropsychological associations begin to develop guidelines regarding appropriate content for websites and identify and continuously monitor websites that contain threatening information

    The content of gender stereotypes embedded in language use

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    Gender stereotypes have endured despite substantial change in gender roles. Previous work has assessed how gender stereotypes affect language production in particular interactional contexts. Here, we assessed communication biases where context was less specified: written texts to diffuse audiences. We used Latent Semantic Analysis (LSA) to computationally quantify the similarity in meaning between gendered names and stereotype-linked terms in these communications. This revealed that female names were more similar in meaning to the proscriptive (undesirable) masculine terms, such as emotional
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