1,524 research outputs found

    Detection of Anomalous Reactor Activity Using Antineutrino Count Rate Evolution Over the Course of a Reactor Cycle

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    This paper analyzes the sensitivity of antineutrino count rate measurements to changes in the fissile content of civil power reactors. Such measurements may be useful in IAEA reactor safeguards applications. We introduce a hypothesis testing procedure to identify statistically significant differences between the antineutrino count rate evolution of a standard 'baseline' fuel cycle and that of an anomalous cycle, in which plutonium is removed and replaced with an equivalent fissile worth of uranium. The test would allow an inspector to detect anomalous reactor activity, or to positively confirm that the reactor is operating in a manner consistent with its declared fuel inventory and power level. We show that with a reasonable choice of detector parameters, the test can detect replacement of 73 kg of plutonium in 90 days with 95% probability, while controlling the false positive rate at 5%. We show that some improvement on this level of sensitivity may be expected by various means, including use of the method in conjunction with existing reactor safeguards methods. We also identify a necessary and sufficient daily antineutrino count rate to achieve the quoted sensitivity, and list examples of detectors in which such rates have been attained.Comment: 9 pages, 7 figures, submitted to J. Appl. Phy

    Sensitivity of seismically cued antineutrino detectors to nuclear explosions

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    We evaluate the sensitivity of large, gadolinium-doped water detectors to antineutrinos released by nuclear fission explosions, using updated signal and background models and taking advantage of the capacity for seismic observations to provide an analysis trigger. Under certain realistic conditions, the antineutrino signature of a 250-kiloton pure fission explosion could be identified several hundred kilometers away in a detector about the size of the largest module currently proposed for a basic physics experiment. In principle, such an observation could provide rapid confirmation that the seismic signal coincided with a fission event, possibly useful for international monitoring of nuclear weapon tests. We discuss the limited potential for seismically cued antineutrino observations to constrain fission yield, differentiate pure fission from fusion-enhanced weapon tests, indicate that the seismic evidence of an explosion had been intentionally masked, or verify the absence of explosive testing in a targeted area. We conclude that advances in seismic monitoring and neutrino physics have made the detection of explosion-derived antineutrinos more conceivable than previously asserted, but the size and cost of sufficiently sensitive detectors continue to limit applications

    Detection of Anomalous Reactor Activity Using Antineutrino Count Rate Evolution Over the Course of a Reactor Cycle

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    This paper analyzes the sensitivity of antineutrino count rate measurements to changes in the fissile content of civil power reactors. Such measurements may be useful in IAEA reactor safeguards applications. We introduce a hypothesis testing procedure to identify statistically significant differences between the antineutrino count rate evolution of a standard 'baseline' fuel cycle and that of an anomalous cycle, in which plutonium is removed and replaced with an equivalent fissile worth of uranium. The test would allow an inspector to detect anomalous reactor activity, or to positively confirm that the reactor is operating in a manner consistent with its declared fuel inventory and power level. We show that with a reasonable choice of detector parameters, the test can detect replacement of 73 kg of plutonium in 90 days with 95% probability, while controlling the false positive rate at 5%. We show that some improvement on this level of sensitivity may be expected by various means, including use of the method in conjunction with existing reactor safeguards methods. We also identify a necessary and sufficient daily antineutrino count rate to achieve the quoted sensitivity, and list examples of detectors in which such rates have been attained.Comment: 9 pages, 7 figures, submitted to J. Appl. Phy

    Two-Phase Emission Detector for Measuring Coherent Neutrino-Nucleus Scattering

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    Coherent scattering is a flavor-blind, high-rate, as yet undetected neutrino interaction predicted by the Standard Model. We propose to use a compact (kg-scale), two-phase (liquid-gas) argon ionization detector to measure coherent neutrino scattering off nuclei. In our approach, neutrino-induced nuclear recoils in the liquid produce a weak ionization signal, which is transported into a gas under the influence of an electric field, amplified via electroluminescence, and detected by phototubes or avalanche diodes. This paper describes the features of the detector, and estimates signal and background rates for a reactor neutrino source. Relatively compact detectors of this type, capable of detecting coherent scattering, offer a new approach to flavor-blind detection of man-made and astronomical neutrinos, and may allow development of compact neutrino detectors capable of non-intrusive real-time monitoring of fissile material in reactors.Comment: 5 pages, Nuclear Science Symposium, Portland, OR, Oct 19-25, 200

    Global Diffusion of the Internet VI: The Internet in Togo

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    The Global Diffusion of the Internet (GDI) framework is used to examine Internet diffusion in Togo along six dimensions: Pervasiveness, Geographical Dispersion, Sectoral Absorption, Connectivity Infrastructure, Organizational Infrastructure, and Sophistication of Use. The Internet in Togo originated in the private sector in 1996. In the years that followed, the Togolese Internet grew at a slower rate than the Internet in many other countries over the same period of time. After examining how each dimension evolved, this study concludes, amongst many suggestions, that the Togolese government should encourage more telecommunication infrastructure development by allowing private companies to utilize Togo Telecom\u27s network

    Understanding and Supporting Directed Content Sharing on the Web

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    To find interesting, personally relevant web content, we often rely on friends and colleagues to pass links along as they encounter them. In this paper, we study and augment link-sharing via e-mail, the most popular means of sharing web content today. Armed with survey data indicating that active sharers of novel web content are often those that actively seek it out, we present FeedMe, a plug-in for Google Reader that makes directed sharing of content a more salient part of the user experience. Our survey research indicates that sharing is moderated by concern about relevancy to the recipient, a desire to send only novel content to the recipient, and the effort required to share. FeedMe allays these concerns by recommending friends who may be interested in seeing the content, providing information on what the recipient has seen and how many emails they have received recently, and giving recipients the opportunity to provide lightweight feedback when they appreciate shared content. FeedMe introduces a novel design space for mixed-initiative social recommenders: friends who know the user voluntarily vet the material on the userâ s behalf. We present a two week field experiment (N=60) demonstrating that FeedMeâ s recommendations and social awareness features made it easier and more enjoyable to share content that recipients appreciated and would not have found otherwise

    Purified palmitoleic acid for the reduction of high-sensitivity C-reactive protein and serum lipids: A double-blinded, randomized, placebo controlled study

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    BackgroundPurified palmitoleic acid (16-1; omega-7) has shown lipid-lowering and anti-inflammatory benefits in open label, epidemiologic, and animal studies.ObjectiveOur objective was to perform the first randomized controlled trial of purified palmitoleic acid supplementation in humans.MethodsAdults with dyslipidemia and evidence of mild systemic inflammation (high-sensitivity C-reactive protein [hs-CRP] between 2 and 5 mg/L) were randomly allocated to receive either 220.5 mg of cis-palmitoleic acid (n = 30) or an identical capsule with placebo (1000 mg of medium chain triglycerides, n = 30) once per day for 30 days. Participants were asked to maintain their current diet. Serum lipids and hs-CRP were drawn at baseline and study completion.ResultsAt 30 days, there were significant mean (95% confidence interval [CI]) reductions in CRP (−1.9 [−2.3 to −1.4] mg/L), triglyceride (−30.2 [−40.2 to −25.3] mg/dL), and low-density lipoprotein (LDL) (−8.9 [−12.0 to −5.8] mg/dL), and a significant increase in high-density lipoprotein (HDL) (2.4 [1.5, 3.3] mg/dL) in the intervention group compared with control. These changes equated to 44%, 15%, and 8% reductions in CRP, triglyceride, and LDL respectively, and a 5% increase in HDL compared with control.ConclusionsPurified palmitoleic acid may be useful in the treatment of hypertriglyceridemia with the beneficial added effects of decreasing LDL and hs-CRP and raising HDL. Further study is needed to elucidate mechanisms and establish appropriate human doses
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