Accountability for health: a scoping paper for the LGA health commission

This paper for the Local Government Association Health Commission aims to scope the main issues surrounding the accountability of health services in England in the context of the Commission’s terms of reference. These require the Commission to consider, against a background of what is referred to as a ‘new consensus’ about localism, how local councils might work best with National Health Service and other partners to engage local people in decision-making and empower them to hold the health care commissioning and delivery system to account. In this paper, the authors seek to clarify the different ways in which accountability has been understood and expressed in relation to the NHS, and to offer a framework for assessing both current mechanisms and new proposals

Coronae & Outflows from Helical Dynamos, Compatibility with the MRI, and Application to Protostellar Disks

Magnetically mediated disk outflows are a leading paradigm to explain winds and jets in a variety of astrophysical sources, but where do the fields come from? Since accretion of mean magnetic flux may be disfavored in a thin turbulent disk, and only fields generated with sufficiently large scale can escape before being shredded by turbulence, in situ field production is desirable. Nonlinear helical inverse dynamo theory can provide the desired fields for coronae and outflows. We discuss the implications for contemporary protostellar disks, where the MRI (magneto-rotational instability) can drive turbulence in the inner regions, and primordial protostellar disks, where gravitational instability drives the turbulence. We emphasize that helical dynamos are compatible with the magneto-rotational instability, and clarify the relationship between the two.Comment: 12 pages, LaTeX (with figs); version in press for "Proceedings of the International Workshop on Magnetic Fields and Star Formation: Theory vs. Observation" Madrid, Spain; April 200

An architecture for efficient gravitational wave parameter estimation with multimodal linear surrogate models

The recent direct observation of gravitational waves has further emphasized the desire for fast, low-cost, and accurate methods to infer the parameters of gravitational wave sources. Due to expense in waveform generation and data handling, the cost of evaluating the likelihood function limits the computational performance of these calculations. Building on recently developed surrogate models and a novel parameter estimation pipeline, we show how to quickly generate the likelihood function as an analytic, closed-form expression. Using a straightforward variant of a production-scale parameter estimation code, we demonstrate our method using surrogate models of effective-one-body and numerical relativity waveforms. Our study is the first time these models have been used for parameter estimation and one of the first ever parameter estimation calculations with multi-modal numerical relativity waveforms, which include all l <= 4 modes. Our grid-free method enables rapid parameter estimation for any waveform with a suitable reduced-order model. The methods described in this paper may also find use in other data analysis studies, such as vetting coincident events or the computation of the coalescing-compact-binary detection statistic.Comment: 10 pages, 3 figures, and 1 tabl

A sparse representation of gravitational waves from precessing compact binaries

Many relevant applications in gravitational wave physics share a significant common problem: the seven-dimensional parameter space of gravitational waveforms from precessing compact binary inspirals and coalescences is large enough to prohibit covering the space of waveforms with sufficient density. We find that by using the reduced basis method together with a parametrization of waveforms based on their phase and precession, we can construct ultra-compact yet high-accuracy representations of this large space. As a demonstration, we show that less than $100$ judiciously chosen precessing inspiral waveforms are needed for $200$ cycles, mass ratios from $1$ to $10$ and spin magnitudes $\le 0.9$. In fact, using only the first $10$ reduced basis waveforms yields a maximum mismatch of $0.016$ over the whole range of considered parameters. We test whether the parameters selected from the inspiral regime result in an accurate reduced basis when including merger and ringdown; we find that this is indeed the case in the context of a non-precessing effective-one-body model. This evidence suggests that as few as $\sim 100$ numerical simulations of binary black hole coalescences may accurately represent the seven-dimensional parameter space of precession waveforms for the considered ranges.Comment: 5 pages, 3 figures. The parameters selected for the basis of precessing waveforms can be found in the source file

Star-forming accretion flows and the low-luminosity nuclei of giant elliptical galaxies

The luminosities of the centres of nearby elliptical galaxies are very low compared to models of thin disc accretion on to their black holes at the Bondi rate, typically a few hundredths to a few tenths of a solar mass per year. This has motivated models of inefficiently radiated accretion that invoke weak electron-ion thermal coupling, and/or inhibited accretion rates due to convection or outflows. Here we point out that, even if such processes are operating, a significant fraction of the accreting gas is prevented from reaching the central black hole because it condenses into stars in a gravitationally unstable disc. Star formation occurs inside the Bondi radius (typically ∼100 pc in giant ellipticals), but still relatively far from the black hole in terms of Schwarzschild radii. Star formation depletes and heats the gas disc, eventually leading to a marginally stable, but much reduced, accretion flow to the black hole. We predict the presence of cold (∼100 K), dusty gas discs, containing clustered Hα emission and occasional Type II supernovae, both resulting from the presence of massive stars. Star formation accounts for several features of the M87 system: a thin disc, traced by Hα emission, is observed on scales of about 100 pc, with features reminiscent of spiral arms and dust lanes; the star formation rate inferred from the intensity of Hα emission is consistent with the Bondi accretion rate of the system. Star formation may therefore help to suppress accretion on to the central engines of massive ellipticals. We also discuss some implications for the fuelling of the Galactic Centre and quasar