299 research outputs found

    An Ethics Framework for the COVID-19 Reopening Process

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    As some political leaders are fond of saying, reopening society after months of social distancing is not like flipping a switch. Reopening is a process. It will extend over many, many months. Policy makers will need to continuously re-evaluate whether the guidance they have set for the next stage of reopening still makes sense. Also, for each stage, they will have to decide not only the when, but the how of each reopening decision. When public schools open in the fall, for example, how exactly should that happen? And, at any stage of the reopening process, if cases or hospitalizations exceed a concerning benchmark, decision makers will have to decide which social distancing policies should be re-imposed. This document presents a framework for ethically evaluating the cascade of policy decisions that define the COVID-19 reopening process. These decisions will not and should not be made based on the science alone. Nor should they be driven by the economics alone. Rather, these decisions are best understood as a series of tradeoffs that reflect many shared values in our society, including not only our shared interests in health and economic flourishing, but also our shared interest in other aspects of well-being, and in liberty and justice. These values, and how to think about them in concert, are the subject of ethics. The framework developed here is specifically designed to aid government decision-makers at the state and local levels. Aspects of the framework may also be useful for decision-makers in a variety of private-sector institutions, including manufacturers, retailers, houses of worship, and private schools and universities

    Electro-Magnetic Nucleon Form Factors and their Spectral Functions in Soliton Models

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    It is demonstrated that in simple soliton models essential features of the electro-magnetic nucleon form factors observed over three orders of magnitude in momentum transfer tt are naturally reproduced. The analysis shows that three basic ingredients are required: an extended object, partial coupling to vector mesons, and relativistic recoil corrections. We use for the extended object the standard skyrmion, one vector meson propagator for both isospin channels, and the relativistic boost to the Breit frame. Continuation to timelike tt leads to quite stable results for the spectral functions in the regime from the 2- or 3-pion threshold to about two rho masses. Especially the onset of the continuous part of the spectral functions at threshold can be reliably determined and there are strong analogies to the results imposed on dispersion theoretic approaches by the unitarity constraint.Comment: 24 pages, (RevTeX), 5 PS-figures; Data points in fig.2 and corresponding references added. Final version, to be published in Z.Physik

    Consistent Treatment of Relativistic Effects in Electrodisintegration of the Deuteron

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    The influence of relativistic contributions to deuteron electrodisintegration is systematically studied in various kinematic regions of energy and momentum transfer. As theoretical framework the equation-of-motion and the unitarily equivalent S-matrix approaches are used. In a (p/M)-expansion, all leading order relativistic π\pi-exchange contributions consistent with the Bonn OBEPQ model are included. In addition, static heavy meson exchange currents including boost terms, ÎłÏ€Ï/ω\gamma\pi\rho/\omega-currents, and Δ\Delta-isobar contributions are considered. Sizeable effects from the various relativistic two-body contributions, mainly from π\pi-exchange, have been found in inclusive form factors and exclusive structure functions for a variety of kinematic regions.Comment: 41 pages revtex including 15 postscript figure

    The genome of Δ15, a serotype-converting, Group E1 Salmonella enterica-specific bacteriophage

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    AbstractThe genome sequence of the Salmonella enterica serovar Anatum-specific, serotype-converting bacteriophage Δ15 has been completed. The nonredundant genome contains 39,671 bp and 51 putative genes. It most closely resembles the genome of φV10, an Escherichia coli O157:H7-specific temperate phage, with which it shares 36 related genes. More distant relatives include the Burkholderia cepacia-specific phage, BcepC6B (8 similar genes), the Bordetella bronchiseptica-specific phage, BPP-1 (8 similar genes) and the Photobacterium profundum prophage, P Pφpr1 (6 similar genes).Δ15 gene identifications based on homologies with known gene families include the terminase small and large subunits, integrase, endolysin, two holins, two DNA methylase enzymes (one adenine-specific and one cytosine-specific) and a RecT-like enzyme. Genes identified experimentally include those coding for the serotype conversion proteins, the tail fiber, the major capsid protein and the major repressor. Δ15's attP site and the Salmonella attB site with which it interacts during lysogenization have also been determined

    Calibration of the surface array of the Pierre Auger Observatory

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    The Pierre Auger Observatory is designed to study cosmic rays of the highest energies (>101910^{19}eV). The ground array of the Observatory will consist of 1600 water Cherenkov detectors deployed over 3000 km2^2. The remoteness and large number of detectors require a robust, automatic self-calibration procedure. It relies on the measurement of the average charge collected by a photomultiplier tube from the Cherenkov light produced by a vertical and central through-going muon, determined to 5–10% at the detector via a novel rate-based technique and to 3% precision through analysis of histograms of the charge distribution. The parameters needed for the calibration are measured every minute, allowing for an accurate determination of the signals recorded from extensive air showers produced by primary cosmic rays. The method also enables stable and uniform triggering conditions to be achieved

    Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory

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    Data from the Pierre Auger Observatory are analyzed to search for anisotropies near the direction of the Galactic Centre at EeV energies. The exposure of the surface array in this part of the sky is already significantly larger than that of the fore-runner experiments. Our results do not support previous findings of localized excesses in the AGASA and SUGAR data. We set an upper bound on a point-like flux of cosmic rays arriving from the Galactic Centre which excludes several scenarios predicting sources of EeV neutrons from Sagittarius AA. Also the events detected simultaneously by the surface and fluorescence detectors (the `hybrid' data set), which have better pointing accuracy but are less numerous than those of the surface array alone, do not show any significant localized excess from this direction.Comment: Matches published versio

    Relationship between human tumour angiogenic profile and combretastatin-induced vascular shutdown: an exploratory study

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    Combretastatin-A4-phosphate (CA4P) acts most effectively against immature tumour vasculature. We investigated whether histological angiogenic profile can explain the differential sensitivity of human tumours to CA4P, by correlating the kinetic changes demonstrated by dynamic MRI (DCE-MRI) in response to CA4P, with tumour immunohistochemical angiogenic markers. Tissue was received from 24 patients (mean age 59, range 32–73, 18 women, 6 men). An angiogenic profile was performed using standard immunohistochemical techniques. Dynamic MRI data were obtained for the same patients before and 4 h after CA4P. Three patients showed a statistically significant fall in Ktrans following CA4P, and one a statistically significant fall in IAUGC60. No statistically significant correlations were seen between the continuous or categorical variables and the DCE-MRI kinetic parameters other than between ang-2 and Ktrans (P=0.044). In conclusion, we found no strong relationships between changes in DCE-MRI kinetic variables following CA4P and the immunohistochemical angiogenic profile
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