19,209 research outputs found

    Representation of uncertain multichannel digital signal spaces and study of pattern recognition based on metrics and difference values on fuzzy n-cell number spaces

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    In this paper, we discuss the problem of characterization for uncertain multichannel digital signal spaces, propose using fuzzy n-cell number space to represent uncertain n-channel digital signal space, and put forward a method of constructing such fuzzy n-cell numbers. We introduce two new metrics and concepts of certain types of difference values on fuzzy n -cell number space and study their properties. Further, based on the metrics or difference values appropriately defined, we put forward an algorithmic version of pattern recognition in an imprecise or uncertain environment, and we also give practical examples to show the application and rationality of the proposed technique

    Search method for long-duration gravitational-wave transients from neutron stars

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    We introduce a search method for a new class of gravitational-wave signals, namely long-duration O(hours - weeks) transients from spinning neutron stars. We discuss the astrophysical motivation from glitch relaxation models and we derive a rough estimate for the maximal expected signal strength based on the superfluid excess rotational energy. The transient signal model considered here extends the traditional class of infinite-duration continuous-wave signals by a finite start-time and duration. We derive a multi-detector Bayes factor for these signals in Gaussian noise using \F-statistic amplitude priors, which simplifies the detection statistic and allows for an efficient implementation. We consider both a fully coherent statistic, which is computationally limited to directed searches for known pulsars, and a cheaper semi-coherent variant, suitable for wide parameter-space searches for transients from unknown neutron stars. We have tested our method by Monte-Carlo simulation, and we find that it outperforms orthodox maximum-likelihood approaches both in sensitivity and in parameter-estimation quality.Comment: 20 pages, 9 figures; submitted to PR

    An exemplar model should be able to explain all syntactic priming phenomena : a commentary on Ambridge (2020)

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    The authors argue that Ambridge’s radical exemplar account of language cannot clearly explain all syntactic priming evidence, such as inverse preference effects (greater priming for less frequent structures), and the contrast between short-lived lexical boost and long-lived abstract priming. Moreover, without recourse to a level of abstract syntactic structure, Ambridge’s account cannot explain abstract priming in amnesia patients or cross-linguistic priming. Instead, the authors argue that abstract representations remain the more parsimonious account for the wide variety of syntactic priming phenomena

    Interstellar and Solar System Organic Matter Preserved in Interplanetary Dust

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    Interplanetary dust particles (IDPs) collected in the Earth's stratosphere derive from collisions among asteroids and by the disruption and outgassing of shortperiod comets. Chondritic porous (CP) IDPs are among the most primitive Solar System materials. CPIDPs have been linked to cometary parent bodies by their mineralogy, textures, Ccontent, and dynamical histories. CPIDPs are fragile, finegrained (less than um) assemblages of anhydrous amorphous and crystalline silicates, oxides and sulfides bound together by abundant carbonaceous material. Ancient silicate, oxide, and SiC stardust grains exhibiting highly anomalous isotopic compositions are abundant in CPIDPs, constituting 0.01 - 1 % of the mass of the particles. The organic matter in CPIDPs is isotopically anomalous, with enrichments in D/H reaching 50x the terrestrial SMOW value and 15N/14N ratios up to 3x terrestrial standard compositions. These anomalies are indicative of low T (10100 K) mass fractionation in cold molecular cloud or the outermost reaches of the protosolar disk. The organic matter shows distinct morphologies, including subum globules, bubbly textures, featureless, and with mineral inclusions. Infrared spectroscopy and mass spectrometry studies of organic matter in IDPs reveals diverse species including aliphatic and aromatic compounds. The organic matter with the highest isotopic anomalies appears to be richer in aliphatic compounds. These materials also bear similarities and differences with primitive, isotopically anomalous organic matter in carbonaceous chondrite meteorites. The diversity of the organic chemistry, morphology, and isotopic properties in IDPs and meteorites reflects variable preservation of interstellar/primordial components and Solar System processing. One unifying feature is the presence of subum isotopically anomalous organic globules among all primitive materials, including IDPs, meteorites, and comet Wild2 samples returned by the Stardust mission

    Implementation of the frequency-modulated sideband search method for gravitational waves from low mass X-ray binaries

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    We describe the practical implementation of the sideband search, a search for periodic gravitational waves from neutron stars in binary systems. The orbital motion of the source in its binary system causes frequency-modulation in the combination of matched filters known as the F\mathcal{F}-statistic. The sideband search is based on the incoherent summation of these frequency-modulated F\mathcal{F}-statistic sidebands. It provides a new detection statistic for sources in binary systems, called the C\mathcal{C}-statistic. The search is well suited to low-mass X-ray binaries, the brightest of which, called Sco X-1, is an ideal target candidate. For sources like Sco X-1, with well constrained orbital parameters, a slight variation on the search is possible. The extra orbital information can be used to approximately demodulate the data from the binary orbital motion in the coherent stage, before incoherently summing the now reduced number of sidebands. We investigate this approach and show that it improves the sensitivity of the standard Sco X-1 directed sideband search. Prior information on the neutron star inclination and gravitational wave polarization can also be used to improve upper limit sensitivity. We estimate the sensitivity of a Sco X-1 directed sideband search on 10 days of LIGO data and show that it can beat previous upper limits in current LIGO data, with a possibility of constraining theoretical upper limits using future advanced instruments.Comment: 20 pages, 5 figure

    Sustainable Development and the Commodities Challenge: The Eventual ‘Greening’ of the World Trade Organization?

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    Comprehensive and concerted action by the international community is required to achieve the Sustainable Development Goals (SDGs) set out in the United Nation‘s 2030 Agenda. Yet, the 2030 Agenda is largely silent on a number of key issues of relevance to international regulation, most notably the impact of commodities on sustainable development. This article identifies the central role that trade in commodities plays in sustainable development while outlining the inherent tensions within the fragmented international regulation of commodities‘ trade. This article looks at the World Trade Organisation (WTO) as a site of innovative global governance in tackling the impact of one commodity–fish–examining how the international community and the WTO have been shifting the narrative in meeting the SDGs from one of overlapping or conflicting regimes to cooperative governance

    Aerogel keystones: extraction of complete hypervelocity impact events from aerogel collectors

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    In January 2006, the Stardust mission will return the first samples from a solid solar-system body since Apollo, and the first samples of contemporary interstellar dust ever collected. Although sophisticated laboratory instruments exist for the analysis of Stardust samples, techniques for the recovery of particles and particle residues from aerogel collectors remain primitive. Here we describe our recent progress in developing techniques for extracting small volumes of aerogel, which we have called ``keystones,'' which completely contain particle impacts but minimize the damage to the surrounding aerogel collector. These keystones can be fixed to custom-designed micromachined silicon fixtures (so-called ``microforklifts''). In this configuration the samples are self-supporting, which can be advantageous in situations in which interference from a supporting substrate is undesirable. The keystones may also be extracted and placed onto a substrate without a fixture. We have also demonstrated the capability of homologously crushing these unmounted keystones for analysis techniques which demand flat samples.Comment: 17 pages, 11 figures, submitted to Meteoritics and Planetary Scienc

    Beyond War Crimes: Denazification, National Security and American Deportation and Internment of SS Agents after World War II

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    Streaming video requires RealPlayer to view.The University Archives has determined that this item is of continuing value to OSU's history.David Messenger is assistant professor of history and graduate director for international studies at the University of Wyoming. He is currently a visiting scholar at the Mershon Center for International Security Studies. During his time at Mershon, he will be preparing a study of Nazi party agents repatriated from Spain and Portugal to Germany in 1946 and 1947 following American and British investigations into their wartime and postwar activities. Messenger's research focuses on the transition from war to peace in Europe following the Second World War. He is particularly interested in how the international system, domestic politics, and societies at large dealt with issues of justice and democratization following the experience of Nazi atrocities and the collaboration of many non-Germans in these crimes over the course of the war. Messenger has focused his work on examining the Spanish dictatorship of Gen. Francisco Franco as one place, on the periphery of the war, where themes of collaboration, justice, and continuity raise some interesting questions. His first book, L’Espagne Républicaine: French Policy and Spanish Republicanism in Liberated France was published in 2008 by Sussex Academic Press. He has held fellowships from the Government of Spain and the Center for Advanced Holocaust Studies at the United States Holocaust Memorial Museum in Washington, D.C.Ohio State University. Mershon Center for International Security StudiesEvent Web page, streaming video, event photo
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