1,791 research outputs found

    Negative-Energy Spinors and the Fock Space of Lattice Fermions at Finite Chemical Potential

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    Recently it was suggested that the problem of species doubling with Kogut-Susskind lattice fermions entails, at finite chemical potential, a confusion of particles with antiparticles. What happens instead is that the familiar correspondence of positive-energy spinors to particles, and of negative-energy spinors to antiparticles, ceases to hold for the Kogut-Susskind time derivative. To show this we highlight the role of the spinorial ``energy'' in the Osterwalder-Schrader reconstruction of the Fock space of non-interacting lattice fermions at zero temperature and nonzero chemical potential. We consider Kogut-Susskind fermions and, for comparison, fermions with an asymmetric one-step time derivative.Comment: 14p

    Issues and scenarios for nuclear waste management systems analysis

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    The Planning and Analysis Branch of the Department of Energy's Nuclear Waste Management Programs is developing a new systems integration program. The Pacific Northwest Laboratory was requested to perform a brief scoping analysis of what scenarios, questions, and issues should be addressed by the systems integration program. This document reports on that scoping analysis

    A Cross-Sectional Study of All Clinicians’ Conflict of Interest Disclosures to NHS Hospital Employers in England 2015-2016

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    Objective We set out to document how NHS trusts in the UK record and share disclosures of conflict of interest by their employees. Design Cross-sectional study of responses to a Freedom of Information Act request for Gifts and Hospitality Registers. Setting NHS Trusts (secondary/tertiary care organisations) in England. Participants 236 Trusts were contacted, of which 217 responded. Main outcome measures We assessed all disclosures for completeness and openness, scoring them for achieving each of five measures of transparency. Results 185 Trusts (78%) provided a register. 71 Trusts did not respond within the 28 day time limit required by the FoIA. Most COI registers were incomplete by design, and did not contain the information necessary to assess conflicts of interest. 126/185 (68%) did not record the names of recipients. 47/185 (25%) did not record the cash value of the gift or hospitality. Only 31/185 registers (16%) contained the names of recipients, the names of donors, and the cash amounts received. 18/185 (10%) contained none of: recipient name, donor name, and cash amount. Only 15 Trusts had their disclosure register publicly available online (6%). We generated a transparency index assessing whether each Trust met the following criteria: responded on time; provided a register; had a register with fields identifying donor, recipient, and cash amount; provided a register in a format that allowed further analysis; and had their register publicly available online. Mean attainment was 1.9/5; no NHS trust met all five criteria. Conclusion Overall, recording of employees’ conflicts of interest by NHS trusts is poor. None of the NHS Trusts in England met all transparency criteria. 19 did not respond to our FoIA requests, 51 did not provide a Gifts and Hospitality Register and only 31 of the registers provided contained enough information to assess employees’ conflicts of interest. Despite obligations on healthcare professionals to disclose conflicts of interest, and on organisations to record these, the current system for logging and tracking such disclosures is not functioning adequately. We propose a simple national template for reporting conflicts of interest, modelled on the US ‘Sunshine Act’

    The Savvidy ``ferromagnetic vacuum'' in three-dimensional lattice gauge theory

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    The vacuum effective potential of three-dimensional SU(2) lattice gauge theory in an applied color-magnetic field is computed over a wide range of field strengths. The background field is induced by an external current, as in continuum field theory. Scaling and finite volume effects are analyzed systematically. The first evidence from lattice simulations is obtained of the existence of a nontrivial minimum in the effective potential. This supports a ``ferromagnetic'' picture of gluon condensation, proposed by Savvidy on the basis of a one-loop calculation in (3+1)-dimensional QCD.Comment: 9pp (REVTEX manuscript). Postscript figures appende

    The KMOS^3D Survey: design, first results, and the evolution of galaxy kinematics from 0.7<z<2.7

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    We present the KMOS^3D survey, a new integral field survey of over 600 galaxies at 0.7<z<2.7 using KMOS at the Very Large Telescope (VLT). The KMOS^3D survey utilizes synergies with multi-wavelength ground and space-based surveys to trace the evolution of spatially-resolved kinematics and star formation from a homogeneous sample over 5 Gyrs of cosmic history. Targets, drawn from a mass-selected parent sample from the 3D-HST survey, cover the star formation-stellar mass (M∗M_*) and rest-frame (U−V)−M∗(U-V)-M_* planes uniformly. We describe the selection of targets, the observations, and the data reduction. In the first year of data we detect Halpha emission in 191 M∗=3×109−7×1011M_*=3\times10^{9}-7\times10^{11} Msun galaxies at z=0.7-1.1 and z=1.9-2.7. In the current sample 83% of the resolved galaxies are rotation-dominated, determined from a continuous velocity gradient and vrot/σ>1v_{rot}/\sigma>1, implying that the star-forming 'main sequence' (MS) is primarily composed of rotating galaxies at both redshift regimes. When considering additional stricter criteria, the Halpha kinematic maps indicate at least ~70% of the resolved galaxies are disk-like systems. Our high-quality KMOS data confirm the elevated velocity dispersions reported in previous IFS studies at z>0.7. For rotation-dominated disks, the average intrinsic velocity dispersion decreases by a factor of two from 50 km/s at z~2.3 to 25 km/s at z~0.9 while the rotational velocities at the two redshifts are comparable. Combined with existing results spanning z~0-3, disk velocity dispersions follow an approximate (1+z) evolution that is consistent with the dependence of velocity dispersion on gas fractions predicted by marginally-stable disk theory.Comment: 20 pages, 11 figures, 1 Appendix; Accepted to ApJ November 2

    Recovering 3D structural properties of galaxies from SDSS-like photometry

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    Because of the 3D nature of galaxies, an algorithm for constructing spatial density distribution models of galaxies on the basis of galaxy images has many advantages over surface density distribution approximations. We present a method for deriving spatial structure and overall parameters of galaxies from images and estimate its accuracy and derived parameter degeneracies on a sample of idealised model galaxies. The test galaxies consist of a disc-like component and a spheroidal component with varying proportions and properties. Both components are assumed to be axially symmetric and coplanar. We simulate these test galaxies as if observed in the SDSS project through ugriz filters, thus gaining a set of realistically imperfect images of galaxies with known intrinsic properties. These artificial SDSS galaxies were thereafter remodelled by approximating the surface brightness distribution with a 2D projection of a bulge+disc spatial distribution model and the restored parameters were compared to the initial ones. Down to the r-band limiting magnitude 18, errors of the restored integral luminosities and colour indices remain within 0.05 mag and errors of the luminosities of individual components within 0.2 mag. Accuracy of the restored bulge-to-disc ratios (B/D) is within 40% in most cases, and becomes worse for galaxies with low B/D, but the general balance between bulges and discs is not shifted systematically. Assuming that the intrinsic disc axial ratio is < 0.3, the inclination angles can be estimated with errors < 5deg for most of the galaxies with B/D < 2 and with errors < 15deg up to B/D = 6. Errors of the recovered sizes of the galactic components are below 10% in most cases. In general, models of disc components are more accurate than models of spheroidal components for geometrical reasons.Comment: 15 pages, 13 figures, accepted for publication in RA
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