6,350 research outputs found

    Fixing Food Safety: Protecting America's Food Supply From Farm-to-Fork

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    Provides an overview of the major concerns regarding U.S. food safety, including an ineffective regulatory system, and of food-borne disease threats. Includes lists of recent outbreaks, major causes of food-borne illnesses, and recommended solutions

    Shortchanging America's Health 2008: A State-by-State Look at How Federal Public Health Dollars Are Spent

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    Examines public health indicators in each state, in combination with federal and state funding for programs to promote health. Includes state rankings by funding per capita, percentage of population who are uninsured, disease rates, and other indicators

    Fate of global superconductivity in arrays of long SNS junctions

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    Normal-metal films overlaid with arrays of superconducting islands undergo Berezinskii-Kosterlitz-Thouless (BKT) superconducting transitions at a temperature TBKTT_{BKT}. We present measurements of TBKT_{BKT} for arrays of mesoscopic Nb islands patterned on Au films for a range of island spacings dd. We show that TBKT1/d2T_{BKT} \sim 1/d^2, and explain this dependence in terms of the quasiclassical prediction that the Thouless energy, rather than the superconducting gap, governs the inter-island coupling. We also find two deviations from the quasiclassical theory: (i) TBKTT_{BKT} is sensitive to island height, because the islands are mesoscopic; and (ii) for widely spaced islands the transition appears to lead, not to a superconducting state, but to a finite-resistance "metallic" one.Comment: 12 pages, 4 figure

    Complete information pivotal-voter model with asymmetric group size

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    We study the equilibria of the standard pivotal-voter participation game between two groups of voters of asymmetric sizes (majority and minority), as originally proposed by Palfrey and Rosenthal (Public Choice 41(1):7–53, 1983). We find a unique equilibrium wherein the minority votes with certainty and the majority votes with probability in (0,1); we prove that this is the only equilibrium in which voters of only one group play a pure strategy, and we provide sufficient conditions for its existence. Equilibria where voters of both groups vote with probability in (0, 1) are analyzed numerically

    Complete information pivotal-voter model with asymmetric group size and asymmetric benefits

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    We analyse a standard pivotal-voter model under majority rule, with two rival groups of players, each preferring one of two public policies and simultaneously deciding whether to cast a costly vote, as in Palfrey and Rosenthal (1983). We allow the benefit of the favorite public policy to differ across groups and impose an intuitive refinement, namely that voting probabilities are continuous in the cost of voting to pin down a unique equilibrium. The unique continuous equilibrium depends on a key threshold that compares the sizes of the two groups

    Statistical analysis of Ni nanowires breaking processes: a numerical simulation study

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    A statistical analysis of the breaking behavior of Ni nanowires is presented. Using molecular dynamic simulations, we have determined the time evolution of both the nanowire atomic structure and its minimum cross section (Sm(t)). Accumulating thousands of independent breaking events, Sm histograms are built and used to study the influence of the temperature, the crystalline stretching direction and the initial nanowire size. The proportion of monomers, dimers and more complex structures at the latest stages of the breaking process are calculated, finding important differences among results obtained for different nanowire orientations and sizes. Three main cases have been observed. (A) [111] stretching direction and large nanowire sizes: the wire evolves from more complex structures to monomers and dimers prior its rupture; well ordered structures is presented during the breaking process. (B) Large nanowires stretched along the [100] and [110] directions: the system mainly breaks from complex structures (low probability of finding monomers and dimers), having disordered regions during their breakage; at room temperature, a huge histogram peak around Sm=5 appears, showing the presence of long staggered pentagonal Ni wires with ...-5-1-5-... structure. (C) Initial wire size is small: strong size effects independently on the temperature and stretching direction. Finally, the local structure around monomers and dimmers do not depend on the stretching direction. These configurations differ from those usually chosen in static studies of conductance.Comment: 18 pages, 13 figure

    Ready or Not? Protecting the Public's Health From Diseases, Disasters, and Bioterrorism, 2008

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    Examines ten indicators to assess progress in state readiness to respond to bioterrorism and other public health emergencies. Evaluates the federal government's and hospitals' preparedness. Makes suggestions for funding, restructuring, and other reforms

    Medical Implications of Space Radiation Exposure Due to Low Altitude Polar Orbits

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    Space radiation research has progressed rapidly in recent years, but there remain large uncertainties in predicting and extrapolating biological responses to humans. Exposure to cosmic radiation and Solar Particle Events may pose a critical health risk to future spaceflight crews and can have a serious impact to all biomedical aspects of space exploration. The relatively minimal shielding of the cancelled 1960's Manned Orbiting Laboratory program's space vehicle and the high inclination polar orbits would have left the crew susceptible to high exposures of cosmic radiation and high dose-rate SPEs that are mostly unpredictable in frequency and intensity. In this study, we have modeled the nominal and off-nominal radiation environment that a MOL-like spacecraft vehicle would be exposed to during a 30-day mission using high performance, multi-core computers. Projected doses from a historically large SPE (e.g. the August 1972 solar event) have been analyzed in the context of the MOL orbit profile, providing an opportunity to study its impact to crew health and subsequent contingencies.It is reasonable to presume that future commercial, government, and military spaceflight missions in low-Earth orbit will have vehicles with similar shielding and orbital profiles. Studying the impact of cosmic radiation to the mission's operational integrity and the health of MOL crewmembers provides an excellent surrogate and case-study for future commercial and military spaceflight missions.Comment: 6 pages, 4 figures, 2 table
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