2,203 research outputs found
Influenza vaccination uptake among people aged over 85 years: an audit of primary care practice in the UK
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
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 and , in the extreme mass ratio
limit, . 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 moving in a (quasi-)Schwarzschild background of
mass and submitted to an \O(\nu) 5PN-resummed analytical
radiation reaction force, with . The gravitational wave emission is
calculated via a multipolar Regge-Wheeler-Zerilli type perturbative approach
(valid in the limit ). We consider three mass ratios,
,and we compute the multipolar waveform up to
. 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 . We finally show that there is an {\it excellent
fractional agreement} () (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
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
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 -
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 and , 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
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
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
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
essentially distinct points of the projective plane. Each type gives
rise to a surface obtained by blowing up the points. We classify those
types such that and 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 such
that the points are essentially distinct and is nef, given only
the configuration type of the points and the coefficients .Comment: 14 pages, final versio
Supermassive recoil velocities for binary black-hole mergers with antialigned spins
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 km/s in the case of spinning
configurations, and have lead to predictions of a maximum kick of up to km/s. We test these predictions and demonstrate that kick velocities of at
least 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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