37,450 research outputs found

    Peer assessment of research: how many publications per staff?

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    The UK's higher education funding councils have proposed reducing the number of submitted outputs from four to three in the forthcoming Research Excellence Framework to reduce the burden on panel members. This reduction is considered to be sufficient for panels to form a robust view of the achievements of individuals and their departments. The key issue is whether the subject panels would have sufficient information to judge the quality of research at departmental level with details of only three outputs per staff. Two journal quality indicators are used in this note to test the assumption that three publications is likely to be as useful to the panels as four to measure research quality in three cognate units of assessment (business & management, economics & econometrics and accounting & finance). In fact, the results indicate that two publications would be sufficient, thereby providing more time for a careful assessment of submitted outputs

    The Dummies Guide' to Lottery Design.

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    This paper outlines the issues relevant to the operation of lottery games. We consider how such games should be designed, what a portfolio of games might look like, how the operator should be regulated, how spending on lottery games should be taxed, and what considerations are relevant to the use of the revenue from such games.LOTTERY ; GAMES ; MONEY ; TAXATION

    Behavior of the sodium and hydroxyl nighttime emissions during a stratospheric warming

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    The behavior of the sodium and hydroxyl nighttime emissions during a stratospheric warming has been studied principally by use of data from the airglow photometers on the OGO-4 satellite. It was found that during the late stages of a major warming, both emissions increase appreciably, with the sodium emission returning to normal levels prior to the decrease in hydroxyl emission. The emission behaviors are attributed to temperature and density variations from 70 to 94 km, and a one-dimensional hydrostatic model for that altitude range is used to calculate the effects on the emissions and on the mesospheric ozone densities

    The case for a cold dark matter cusp in Draco

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    We use a new mass modelling method, GravSphere, to measure the central dark matter density profile of the Draco dwarf spheroidal galaxy. Draco's star formation shut down long ago, making it a prime candidate for hosting a 'pristine' dark matter cusp, unaffected by stellar feedback during galaxy formation. We first test GravSphere on a suite of tidally stripped mock 'Draco'-like dwarfs. We show that we are able to correctly infer the dark matter density profile of both cusped and cored mocks within our 95% confidence intervals. While we obtain only a weak inference on the logarithmic slope of these density profiles, we are able to obtain a robust inference of the amplitude of the inner dark matter density at 150pc, ρDM(150pc)\rho_{\rm DM}(150\,{\rm pc}). We show that, combined with constraints on the density profile at larger radii, this is sufficient to distinguish a Λ\Lambda Cold Dark Matter (Λ\LambdaCDM) cusp - that has ρDM(150pc)>1.8×108Mkpc3\rho_{\rm DM}(150\,{\rm pc}) > 1.8 \times 10^8\,{\rm M}_\odot \,{\rm kpc}^{-3} - from alternative dark matter models that have lower inner densities. We then apply GravSphere to the real Draco data. We find that Draco has an inner dark matter density of ρDM(150pc)=2.40.6+0.5×108Mkpc3\rho_{\rm DM}(150\,{\rm pc}) = 2.4_{-0.6}^{+0.5} \times 10^8\,{\rm M}_\odot \,{\rm kpc}^{-3}, consistent with a Λ\LambdaCDM cusp. Using a velocity independent SIDM model, calibrated on Λ\LambdaSIDM cosmological simulations, we show that Draco's high central density gives an upper bound on the SIDM cross section of σ/m<0.57cm2g1\sigma/m < 0.57\,{\rm cm}^2\,{\rm g}^{-1} at 99% confidence. We conclude that the inner density of nearby dwarf galaxies like Draco provides a new and competitive probe of dark matter models.Comment: 19 pages, 11 Figures. Final version accepted for publication in MNRA

    Dark matter heats up in dwarf galaxies

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    Gravitational potential fluctuations driven by bursty star formation can kinematically 'heat up' dark matter at the centres of dwarf galaxies. A key prediction of such models is that, at a fixed dark matter halo mass, dwarfs with a higher stellar mass will have a lower central dark matter density. We use stellar kinematics and HI gas rotation curves to infer the inner dark matter densities of eight dwarf spheroidal and eight dwarf irregular galaxies with a wide range of star formation histories. For all galaxies, we estimate the dark matter density at a common radius of 150pc, ρDM(150pc)\rho_{\rm DM}(150\,\mathrm{pc}). We find that our sample of dwarfs falls into two distinct classes. Those that stopped forming stars over 6Gyrs ago favour central densities ρDM(150pc)>108Mkpc3\rho_{\rm DM}(150\,\mathrm{pc})>10^8\,{\rm M}_\odot\,{\rm kpc}^{-3}, consistent with cold dark matter cusps, while those with more extended star formation favour ρDM(150pc)<108Mkpc3\rho_{\rm DM}(150\,\mathrm{pc})<10^8\,{\rm M}_{\odot}\,{\rm kpc}^{-3}, consistent with shallower dark matter cores. Using abundance matching to infer pre-infall halo masses, M200M_{200}, we show that this dichotomy is in excellent agreement with models in which dark matter is heated up by bursty star formation. In particular, we find that ρDM(150pc)\rho_{\rm DM}(150\,\mathrm{pc}) steadily decreases with increasing stellar mass-to-halo mass ratio, M/M200M_*/M_{200}. Our results suggest that, to leading order, dark matter is a cold, collisionless, fluid that can be kinematically 'heated up' and moved around.Comment: 22 pages, 10 Figures. Final version accepted for publication in MNRA

    Determining the superconducting gap structure in Sr2RuO4 from sound attenuation studies below Tc

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    This work presents a quantitative theoretical study of the sound attenuation in the unconventional multiband superconductor Sr2RuO4 below the superconducting transition temperature Tc. Sound attenuation in this material is shown to have the remarkable property of being able to identify different nodal structures on different bands. The nodal structures on the \gamma band on the one hand, and on the \alpha and \beta bands on the other, are both found to be characterized by the existence of point nodes, but are significantly different in their quantitative aspects.Comment: 7 pages, REVTe

    Zeros of Rydberg-Rydberg Foster Interactions

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    Rydberg states of atoms are of great current interest for quantum manipulation of mesoscopic samples of atoms. Long-range Rydberg-Rydberg interactions can inhibit multiple excitations of atoms under the appropriate conditions. These interactions are strongest when resonant collisional processes give rise to long-range C_3/R^3 interactions. We show in this paper that even under resonant conditions C_3 often vanishes so that care is required to realize full dipole blockade in micron-sized atom samples.Comment: 10 pages, 4 figures, submitted to J. Phys.

    Anomaluos RR Lyrae (V-I)_0 colors in Baade's Window

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    We compare (V-I)_0-(V-K)_0 color-color and (V-I)_0-log P period-color diagrams for Baade's Window and local RRab Lyrae stars. We find that for a fixed log P the Baade's Window RR Lyrae stars are ~0.17 magnitudes redder in (V-I)_0 than the local RR Lyrae stars. We also show that there is no such effect observed in (V-K)_0. We argue that an extinction misestimate towards Baade's Window is not a plausible explanation of the discrepancy. Unlike Baade's Window RR Lyrae stars, the local ones follow a black-body color-color relation and are well approximated by theoretical models. We test two parameters, metallicity and surface gravity, and find that their effects are too small to explain the (V-I)_0 discrepancy between the two groups of stars. We do not provide any explanation for the anomalous (V-I)_0 behavior of the Baade's Window RR Lyrae stars. We note that a similar effect for clump giant stars has been recently reported by Paczynski and we caution that RR Lyrae stars and clump giants, often used as standard candles, can be subject to the same type of systematics.Comment: 10 pages, 7 figures, submitted to Ap

    Short-Chained Oligo(Ethylene Oxide)-Functionalized Gold Nanoparticles: Realization Of Significant Protein Resistance

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    Protein corona formed on nanomaterial surfaces play an important role in the bioavailability and cellular uptake of nanomaterials. Modification of surfaces with oligoethylene glycols (OEG) are a common way to improve the resistivity of nanomaterials to protein adsorption. Short-chain ethylene oxide (EO) oligomers have been shown to improve the protein resistance of planar Au surfaces. We describe the application of these EO oligomers for improved protein resistance of 30 nm spherical gold nanoparticles (AuNPs). Functionalized AuNPs were characterized using UV-Vis spectroscopy, dynamic light scattering (DLS), and zeta potential measurements. Capillary electrophoresis (CE) was used for separation and quantitation of AuNPs and AuNP-protein mixtures. Specifically, nonequilibrium capillary electrophoresis of equilibrium mixtures (NECEEM) was employed for the determination of equilibrium and rate constants for binding between citrate-stabilized AuNPs and two model proteins, lysozyme and fibrinogen. Semi-quantitative CE analysis was carried out for mixtures of EO-functionalized AuNPs and proteins, and results demonstrated a 2.5-fold to 10-fold increase in protein binding resistance to lysozyme depending on the AuNP surface functionalization and a 15-fold increase in protein binding resistance to fibrinogen for both EO oligomers examined in this study
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