225 research outputs found

    Isotropic Radio Background from Quark Nugget Dark Matter

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    Recent measurements by the ARCADE2 experiment unambiguously show an excess in the isotropic radio background at frequencies below the GHz scale. We argue that this excess may be a natural consequence of the interaction of visible and dark matter in the early universe if the dark matter consists of heavy nuggets of quark matter. Explanation of the observed radio band excess requires the introduction of no new parameters, rather we exploit the same dark matter model and identical normalization parameters to those previously used to explain other excesses of diffuse emission from the centre of our galaxy. These previously observed excesses include the WMAP Haze of GHz radiation, keV X -ray emission and MeV gamma-ray radiation.Comment: updated plot and references reflecting a revised analysis of the isotropic radio background exces

    A Quark Matter Contribution to the Cosmic Ray Spectrum

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    I will describe a possible dark matter model in which the dark matter is composed of heavy “nuggets” of standard model quarks and antiquarks bound in a high density phase of QCD. If objects of this type are formed early in the universe's history they may provide the observed dark matter content. In this scenario the nuggets are dark not because of their fundamentally weak interactions but because of the incredibly small number density required to explain the observed mass density of the dark matter. The correspondingly small flux of these objects through the earth renders them invisible to conventional high sensitivity dark matter searches intended to detect weakly interacting particles with a flux many orders of magnitude larger. Instead the greatest search potential for dark matter models of this form may come from the largest scale cosmic ray detectors. I will briefly describe the properties of quark nugget dark matter and then use these properties in order to predict the signal they would produce in a variety of cosmic ray detectors

    Final Narrative

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    https://lib.dr.iastate.edu/carver_narratives/1013/thumbnail.jp

    Reliability Issues Caused By The Retirement Of Large Thermal Generation Facilities: An Irish Case Study

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    Like all developed countries Ireland faces increasing pressure to reduce their carbon footprint. Part of the governments plans include the scaling back of fossil fuel generation facilities and increasing renewable resources. Moneypoint is Irelands only coal fired generation station. In 2025 Moneypoint is due to reach the end of its life cycle. At this point the Irish government will have to make a decission on the future of the generation facility. Currently Moneypoint is responsible for the generation of approximately 10 % of Irelands energy needs. In this paper, the removal of Moneypoint from the Irish generation portfolio will be investigated. A series of simulations have been completed using historic demand and generation data. An initial assessment of the system was completed to verify the assessment technique. All three Moneypoint generation units were then removed and the relibaility of the system dropped dramatically. From this point assessments were completed to determine the quantity of wind generation that would be needed to bring the system back to a stable level. The assessments completed indicate that in 2025 an additional 3000 MW of wind generation will be needed if Moneypoint is removed from the generation portfolio of the country

    Rule Governed Variation in Elicited Narratives in Peruvian Sign Language (LSP)

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    Wordless books offer a single-source methodology for the crosslinguistic elicitation of both spoken and signed narratives (Chafe, 1974). Yet, Labov (1972), in Sociolinguistic Patterns, argued that the most natural narratives result when subjects are emotionally engaged in their own life stories. We added a twist to the traditional single-source elicitation using Mercer Mayer’s book, Frog, Where are you? (Slobin 2004, 2005), where Deaf subjects, tested in groups, saw each other’s recountings. They embellished each upon the other in a spirit of one-upmanship, rendering richer and more natural narratives with the feel of storytelling in a face-to face tradition. This poster presents the results of transcription (using Elán, an annotation software) and linguistic analysis of two excerpts from this group elicitation (n=4) compared with a single-subject elicitation of the same narrative. The group elicitation yielded a richer and more varied use of options (involving classifiers, Size and Shape Specifiers, role shift, affect marking, facial adverbs, and narrative perspective, including personification), yet worked within the same LSP grammatical constraints in terms of lexical choice, use of space, ordering of ground before figure, perspective, agreement, tense, syntax, and non-manual grammar marking). We present a comparative analysis of elicitation under these two conditions and argue for the group elicitation as a more natural and productive approach to single source elicitation
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