2,197 research outputs found

    Influenza vaccination uptake among people aged over 85 years: an audit of primary care practice in the UK

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    Public health research and national guidelines have advocated for seasonal influenza vaccination in the elderly. General practice has established itself as an ideal setting for the safe administration and monitoring of vaccines.1 Due to waning immune systems and high levels of co-morbidities, the elderly are especially vulnerable to the acquisition of infectious diseases.2 Influenza in the elderly results in increased levels of hospitalisation, morbidity and mortality. This section of society clearly benefits from annual vaccination against circulating seasonal strains of influenza virus.3 Since a major policy change in 2000 from riskrelated vaccine administration to age-related vaccine administration, vaccine uptake on average has increased.1 Little is known about the vaccine uptake patterns in the elderly population aged 85 years and over. The primary objective was to audit the influenza vaccination uptake in Amherst Medical Practice among individuals aged over 85 years. Secondary objectives were: to determine the proportion of recurrent non-uptake of seasonal influenza vaccination in the primary care setting, to identify the underlying factors associated with recurrent non-uptake of seasonal influenza vaccination, and provide baseline information to target and improve vaccine uptake among patients aged over 85 years

    Binary black hole merger in the extreme-mass-ratio limit: a multipolar analysis

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    Building up on previous work, we present a new calculation of the gravitational wave (GW) emission generated during the transition from quasi-circular inspiral to plunge, merger and ringdown by a binary system of nonspinning black holes, of masses m1m_1 and m2m_2, in the extreme mass ratio limit, m1m2≪(m1+m2)2m_1 m_2\ll(m_1+m_2)^2. The relative dynamics of the system is computed {\it without making any adiabatic approximation} by using an effective one body (EOB) description, namely by representing the binary by an effective particle of mass μ=m1m2/(m1+m2)\mu=m_1 m_2/(m_1+m_2) moving in a (quasi-)Schwarzschild background of mass M=m1+m2M=m_1+m_2 and submitted to an \O(\nu) 5PN-resummed analytical radiation reaction force, with ν=μ/M\nu=\mu/M. The gravitational wave emission is calculated via a multipolar Regge-Wheeler-Zerilli type perturbative approach (valid in the limit ν≪1\nu\ll 1). We consider three mass ratios, ν=10−2,10−3,10−4\nu={10^{-2},10^{-3},10^{-4}},and we compute the multipolar waveform up to ℓ=8\ell=8. We estimate energy and angular momentum losses during the quasi-universal and quasi-geodesic part of the plunge phase and we analyze the structure of the ringdown. We calculate the gravitational recoil, or "kick", imparted to the merger remnant by the gravitational wave emission and we emphasize the importance of higher multipoles to get a final value of the recoil v/(cν2)=0.0446v/(c\nu^2)=0.0446. We finally show that there is an {\it excellent fractional agreement} (∼10−3\sim 10^{-3}) (even during the plunge) between the 5PN EOB analytically-resummed radiation reaction flux and the numerically computed gravitational wave angular momentum flux. This is a further confirmation of the aptitude of the EOB formalism to accurately model extreme-mass-ratio inspirals, as needed for the future space-based LISA gravitational wave detector.Comment: 20 pages, 12 figures. Version published in Phys. Rev.

    Resonant recoil in extreme mass ratio binary black hole mergers

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    The inspiral and merger of a binary black hole system generally leads to an asymmetric distribution of emitted radiation, and hence a recoil of the remnant black hole directed opposite to the net linear momentum radiated. The recoil velocity is generally largest for comparable mass black holes and particular spin configurations, and approaches zero in the extreme mass ratio limit. It is generally believed that for extreme mass ratios eta<<1, the scaling of the recoil velocity is V {\propto} eta^2, where the proportionality coefficient depends on the spin of the larger hole and the geometry of the system (e.g. orbital inclination). Here we show that for low but nonzero inclination prograde orbits and very rapidly spinning large holes (spin parameter a*>0.9678) the inspiralling binary can pass through resonances where the orbit-averaged radiation-reaction force is nonzero. These resonance crossings lead to a new contribution to the kick, V {\propto} eta^{3/2}. For these configurations and sufficiently extreme mass ratios, this resonant recoil is dominant. While it seems doubtful that the resonant recoil will be astrophysically significant, its existence suggests caution when extrapolating the results of numerical kick results to extreme mass ratios and near-maximal spins.Comment: fixed references; matches PRD accepted version (minor revision); 9 pages, 2 figure

    Resolutions of ideals of six fat points in P^2

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    The graded Betti numbers of the minimal free resolution (and also therefore the Hilbert function) of the ideal of a fat point subscheme Z of P^2 are determined whenever Z is supported at any 6 or fewer distinct points. All results hold over an algebraically closed field k of arbitrary characteristic.Comment: 21 pp., final versio

    Gravitational Radiation from Plunging Orbits - Perturbative Study -

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    Numerical relativity has recently yielded a plethora of results about kicks from spinning mergers which has, in turn, vastly increased our knowledge about the spin interactions of black hole systems. In this work we use black hole perturbation theory to calculate accurately the gravitational waves emanating from the end of the plunging stage of an extreme mass ratio merger in order to further understand this phenomenon. This study focuses primarily on spin induced effects with emphasis on the maximally spinning limit and the identification of possible causes of generic behavior. We find that gravitational waves emitted during the plunging phase exhibit damped oscillatory behavior, corresponding to a coherent excitation of quasi-normal modes by the test particle. This feature is universal in the sense that the frequencies and damping time do not depend on the orbital parameters of the plunging particle. Furthermore, the observed frequencies are distinct from those associated with the usual free quasi-normal ringing. Our calculation suggests that a maximum in radiated energy and momentum occurs at spin parameters equal to a/M=0.86a/M=0.86 and a/M=0.81a/M=0.81, respectively for the plunge stage of a polar orbit. The dependence of linear momentum emission on the angle at which a polar orbit impacts the horizon is quantified. One of the advantages of the perturbation approach adopted here is that insight into the actual mechanism of radiation emission and its relationship to black hole ringing is obtained by carefully identifying the dominant terms in the expansions used

    The effect of gravitational-wave recoil on the demography of massive black holes

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    The coalescence of massive black hole (MBH) binaries following galaxy mergers is one of the main sources of low-frequency gravitational radiation. A higher-order relativistic phenomenon, the recoil as a result of the non-zero net linear momentum carried away by gravitational waves, may have interesting consequences for the demography of MBHs at the centers of galaxies. We study the dynamics of recoiling MBHs and its observational consequences. The ``gravitational rocket'' may: i) deplete MBHs from late-type spirals, dwarf galaxies, and stellar clusters; ii) produce off-nuclear quasars, including unusual radio morphologies during the recoil of a radio-loud source; and iii) give rise to a population of interstellar and intergalactic MBHs.Comment: emulateapj, 5 pages, 2 figures, to appear in the ApJ Letter

    Myths of a Near Past: Envisioning Finance Capitalism anno 2007

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    This paper seeks to extend earlier work on particular features and manifestations of capitalism (De Cock et al., 2001). Our 2001 Myths of a Near Future paper offered ephemera readers a large depository of images concerning the New Economy. Eight years later our focus has shifted to Finance Capitalism. Over the course of the year 2007 we cut out and scanned 81 ads placed by financial institutions in the Financial Times. Our analysis of these aims to provide a sense of how the financial world ?showed up? in this pivotal year, whilst illustrating how its representations were interwoven with fantasy throughout. We also hope that the ensemble of images associated with the paper will be creatively reassembled by its readers and possibly provide a useful teaching aid

    Configuration types and cubic surfaces

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    This paper is a sequel to the paper \cite{refGH}. We relate the matroid notion of a combinatorial geometry to a generalization which we call a configuration type. Configuration types arise when one classifies the Hilbert functions and graded Betti numbers for fat point subschemes supported at n≤8n\le8 essentially distinct points of the projective plane. Each type gives rise to a surface XX obtained by blowing up the points. We classify those types such that n=6n=6 and −KX-K_X is nef. The surfaces obtained are precisely the desingularizations of the normal cubic surfaces. By classifying configuration types we recover in all characteristics the classification of normal cubic surfaces, which is well-known in characteristic 0 \cite{refBW}. As an application of our classification of configuration types, we obtain a numerical procedure for determining the Hilbert function and graded Betti numbers for the ideal of any fat point subscheme Z=m1p1+...+m6p6Z=m_1p_1+...+m_6p_6 such that the points pip_i are essentially distinct and −KX-K_X is nef, given only the configuration type of the points p1,...,p6p_1,...,p_6 and the coefficients mim_i.Comment: 14 pages, final versio

    Supermassive recoil velocities for binary black-hole mergers with antialigned spins

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    Recent calculations of the recoil velocity in binary black hole mergers have found the kick velocity to be of the order of a few hundred km/s in the case of non-spinning binaries and about 500500 km/s in the case of spinning configurations, and have lead to predictions of a maximum kick of up to 13001300 km/s. We test these predictions and demonstrate that kick velocities of at least 25002500 km/s are possible for equal-mass binaries with anti-aligned spins in the orbital plane. Kicks of that magnitude are likely to have significant repercussions for models of black-hole formation, the population of intergalactic black holes and the structure of host galaxies.Comment: Final version, published by Phys. Rev. Lett.; title changed according to suggestion of PRL; note added after preparation of manuscrip
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