2,047 research outputs found

    The National Dialogue on the Quadrennial Homeland Security Review

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    Six years after its creation, the Department of Homeland Security (DHS) undertook the first Quadrennial Homeland Security Review (QHSR) to inform the design and implementation of actions to ensure the safety of the United States and its citizens. This review, mandated by the Implementing the 9/11 Commission Recommendations Act of 2007, represents the first comprehensive examination of the homeland security strategy of the nation. The QHSR includes recommendations addressing the long-term strategy and priorities of the nation for homeland security and guidance on the programs, assets, capabilities, budget, policies, and authorities of the department.Rather than set policy internally and implement it in a top-down fashion, DHS undertook the QHSR in a new and innovative way by engaging tens of thousands of stakeholders and soliciting their ideas and comments at the outset of the process. Through a series of three-week-long, web-based discussions, stakeholders reviewed materials developed by DHS study groups, submitted and discussed their own ideas and priorities, and rated or "tagged" others' feedback to surface the most relevant ideas and important themes deserving further consideration.Key FindingsThe recommendations included: (1) DHS should enhance its capacity for coordinating stakeholder engagement and consultation efforts across its component agencies, (2) DHS and other agencies should create special procurement and contracting guidance for acquisitions that involve creating or hosting such web-based engagement platforms as the National Dialogue, and (3) DHS should begin future stakeholder engagements by crafting quantitative metrics or indicators to measure such outcomes as transparency, community-building, and capacity

    Half Life of the Doubly-magic r-Process Nucleus 78Ni

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    Nuclei with magic numbers serve as important benchmarks in nuclear theory. In addition, neutron-rich nuclei play an important role in the astrophysical rapid neutron-capture process (r-process). 78Ni is the only doubly-magic nucleus that is also an important waiting point in the r-process, and serves as a major bottleneck in the synthesis of heavier elements. The half-life of 78Ni has been experimentally deduced for the first time at the Coupled Cyclotron Facility of the National Superconducting Cyclotron Laboratory at Michigan State University, and was found to be 110 (+100 -60) ms. In the same experiment, a first half-life was deduced for 77Ni of 128 (+27 -33) ms, and more precise half-lives were deduced for 75Ni and 76Ni of 344 (+20 -24) ms and 238 (+15 -18) ms respectively.Comment: 4 pages, 3 figure

    Measurements of Charged Current Reactions of νe\nu_e on 12C^{12}C

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    Charged Current reactions of νe\nu_e on 12C^{12}C have been studied using a μ+\mu^+ decay-at-rest νe\nu_e beam at the Los Alamos Neutron Science Center. The cross section for the exclusive reaction 12C(νe,e)12Ng.s.^{12}C(\nu_e,e^-)^{12}N_{g.s.} was measured to be (8.9±0.3±0.9)×1042(8.9\pm0.3\pm0.9)\times10^{-42} cm2^2. The observed energy dependence of the cross section and angular distribution of the outgoing electron agree well with theoretical expectations. Measurements are also presented for inclusive transitions to 12N^{12}N excited states, 12C(νe,e)12N^{12}C(\nu_e,e^-)^{12}N^* and compared with theoretical expectations. The measured cross section, (4.3±0.4±0.6)×1042(4.3\pm0.4\pm0.6)\times10^{-42} cm2^2, is somewhat lower than previous measurements and than a continuum random phase approximation calculation. It is in better agreement with a recent shell model calculation.Comment: 34 pages, 18 figures, accepted to PRC, replaced with the accepted on

    Initial Results from the CHOOZ Long Baseline Reactor Neutrino Oscillation Experiment

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    Initial results are presented from CHOOZ, a long-baseline reactor-neutrino vacuum-oscillation experiment. Electron antineutrinos were detected by a liquid scintillation calorimeter located at a distance of about 1 km. The detector was constructed in a tunnel protected from cosmic rays by a 300 MWE rock overburden. This massive shielding strongly reduced potentially troublesome backgrounds due to cosmic-ray muons, leading to a background rate of about one event per day, more than an order of magnitude smaller than the observed neutrino signal. From the statistical agreement between detected and expected neutrino event rates, we find (at 90% confidence level) no evidence for neutrino oscillations in the electron antineutrino disappearance mode for the parameter region given approximately by deltam**2 > 0.9 10**(-3) eV**2 for maximum mixing and (sin(2 theta)**2) > 0.18 for large deltam**2.Comment: 13 pages, Latex, submitted to Physics Letters

    Evidence for Neutrino Oscillations from Muon Decay at Rest

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    A search for nu_bar_mu to nu_bar_e oscillations has been conducted at the Los Alamos Meson Physics Facility using nu_bar_mu from mu+ decay at rest. The nu_bar_e are detected via the reaction (nu_bar_e,p) -> (e+,n), correlated with the 2.2 MeV gamma from (n,p) -> (d,gamma). The use of tight cuts to identify e+ events with correlated gamma rays yields 22 events with e+ energy between 36 and 60 MeV and only 4.6 (+/- 0.6) background events. The probability that this excess is due entirely to a statistical fluctuation is 4.1E-08. A chi^2 fit to the entire e+ sample results in a total excess of 51.8 (+18.7) (-16.9) (+/- 8.0) events with e+ energy between 20 and 60 MeV. If attributed to nu_bar_mu -> nu_bar_e oscillations, this corresponds to an oscillation probability (averaged over the experimental energy and spatial acceptance) of 0.0031 (+0.0011) (-0.0010) (+/- 0.0005).Comment: 57 pages, 34 figures, revtex, additional information available at http://nu1.lampf.lanl.gov/~lsnd

    Limits on Neutrino Oscillations from the CHOOZ Experiment

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    We present new results based on the entire CHOOZ data sample. We find (at 90% confidence level) no evidence for neutrino oscillations in the anti_nue disappearance mode, for the parameter region given by approximately Delta m**2 > 7 x 10**-4 eV^2 for maximum mixing, and sin**2(2 theta) = 0.10 for large Delta m**2. Lower sensitivity results, based only on the comparison of the positron spectra from the two different-distance nuclear reactors, are also presented; these are independent of the absolute normalization of the anti_nue flux, the cross section, the number of target protons and the detector efficiencies.Comment: 19 pages, 11 figures, Latex fil

    Search for neutrino oscillations on a long base-line at the CHOOZ nuclear power station

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    This final article about the CHOOZ experiment presents a complete description of the electron antineutrino source and detector, the calibration methods and stability checks, the event reconstruction procedures and the Monte Carlo simulation. The data analysis, systematic effects and the methods used to reach our conclusions are fully discussed. Some new remarks are presented on the deduction of the confidence limits and on the correct treatment of systematic errors.Comment: 41 pages, 59 figures, Latex file, accepted for publication by Eur.Phys.J.

    The decline of water hyacinth on Lake Victoria was due to biological control by Neochetina spp

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    There has been some debate recently about the cause of the decline of water hyacinth on Lake Victoria. While much of this evidence points to classical biological control as the major factor, the El Niño associated weather pattern of the last quarter of 1997 and the first half of 1998 has confused the issue. We argue first that the reductions in water hyacinth on Lake Victoria were ultimately caused by the widespread and significant damage to plants by Neochetina spp., although this process was increased by the stormy weather associated with the El Niño event; second that increased waves and current on Lake Victoria caused by El Niño redistributed water hyacinth plants around the lake; and third that a major lake-wide resurgence of water hyacinth plants on Lake Victoria has not occurred and will not occur unless the weevil populations are disrupted. We conclude that the population crash of water hyacinth on Lake Victoria would not have occurred in the absence of the weevils, but that it may have been hastened by stormy weather associated with the El Niño event
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