Kinematically Detected Halo Streams

Clues to the origins and evolution of our Galaxy can be found in the kinematics of stars around us. Remnants of accreted satellite galaxies produce over- densities in velocity-space, which can remain coherent for much longer than spatial over-densities. This chapter reviews a number of studies that have hunted for these accretion relics, both in the nearby solar-neighborhood and the more-distant stellar halo. Many observational surveys have driven this field forwards, from early work with the Hipparcos mission, to contemporary surveys like RAVE & SDSS. This active field continues to flourish, providing many new discoveries, and will be revolutionised as the Gaia mission delivers precise proper motions for a billion stars in our Galaxy.Comment: 27 pages, 10 figures. Chapter from Springer ASSL Volume entitled "Tidal Streams in the Local Group and Beyond". Affluent readers may wish to purchase the full volume here: http://link.springer.com/book/10.1007/978-3-319-19336-

Industry structure and regulation

As private firms become increasingly involved in the development of key infrastructure, redefining the role of government from that of serviceprovider to regulator presents both challenges and opportunities. The factors that give rise to sector reforms color how much policymakers invest in regulatory design during the reform process. Nevertheless, two factors are essential to sustainable sector and regulatory reform. First, the right structure must be established for the industry concerned, a structure that allows competition appropriate for that industry. Second, the objectives of regulation must be well defined, with a clear distinction between policymaking, policy implementation, and operations. The extent to which competition can be harnessed to help make regulation efficient, effective, and sustainable depends on the intrinsic technical characteristics of the sector. Each decision affects the sustainability of the regulatory regime in the face of the threat of regulatory capture (both political and commercial). Careful regulatory design is crucial not only for successful sectoral reform but also to balance the interests of various actors (government, consumers, developers, investors, and financiers). One model that has been relatively successful combines new entry, unbundled services, and the unambiguous spelling out of the legal rights and duties for both public and private service providers, administered by an autonomous regulatory authority. Problems with regulation often result as much from inadequate attention to sector structure and fostering competition as from weaknesses in the regulatory authority's institutional capacity. As for the tools of regulation, despite differences in some details between licenses and concessions (and their many contractual variations), these are basically instruments that establish the rights and obligations of contracting parties. Choices about where these rights and obligations are located in the legal hierarchy are shaped by a country's institutional capacity and legal traditions. But the existence of instruments to establish those rights and obligations does not eliminate the need for institutionsto administer them, and thus carry out the regulatory function. Establishing effective sectorwide regulation can be difficult in a developing country, but it is necessary. Policymakers will be able to create effective regulatory regimes where adequate attention is given to sector structure, competition, and institution-building.Environmental Economics&Policies,Trade Finance and Investment,Knowledge Economy,ICT Policy and Strategies,Decentralization,Environmental Economics&Policies,Administrative&Regulatory Law,ICT Policy and Strategies,Water and Industry,Knowledge Economy

The Lives of Stars: Insights From the TGAS-RAVE-LAMOST Dataset

In this paper we investigate how the chemical and kinematic properties of stars vary as a function of age. Using data from a variety of photometric, astrometric and spectroscopic surveys, we calculate the ages, phase space information and orbits for $\sim$125,000 stars covering a wide range of stellar parameters. We find indications that the inner regions of the disk reached high levels of enrichment early, while the outer regions were more substantially enriched in intermediate and recent epochs. We consider these enrichment histories through comparison of the ages of stars, their metallicities, and kinematic properties, such as their angular momentum in the solar neighborhood (which is a proxy for orbital radius). We calculate rates at which the velocity dispersions evolve, investigate the Oort constants for different aged populations (finding a slightly negative $\partial V_{C} / \partial R$ and $\partial V_{R} / \partial R$ for all ages, being most negative for the oldest stars), as well as examine the behavior of the velocity vertex deviation angle as a function of age (which we find to fall from $\sim$15 degrees for the 2 Gyr aged population to $\sim$6 degrees at around 6.5 Gyr of age, after which it remains unchanged). We find evidence for stellar churning, and find that the churned stars have a slightly younger age distribution than the rest of the data.Comment: 18 Pages, 14 Figures, Accepted Ap

Red Runaways II: Low mass Hills stars in SDSS Stripe 82

Stars ejected from the Galactic centre can be used to place important constraints on the Milky Way potential. Since existing hypervelocity stars are too distant to accurately determine orbits, we have conducted a search for nearby candidates using full three-dimensional velocities. Since the efficacy of such studies are often hampered by deficiencies in proper motion catalogs, we have chosen to utilize the reliable, high-precision SDSS Stripe 82 proper motion catalog. Although we do not find any candidates which have velocities in excess of the escape speed, we identify 226 stars on orbits that are consistent with Galactic centre ejection. This number is significantly larger than what we would expect for halo stars on radial orbits and cannot be explained by disk or bulge contamination. If we restrict ourselves to metal-rich stars, we find 29 candidates with [Fe/H] > -0.8 dex and 10 with [Fe/H] > -0.6 dex. Their metallicities are more consistent with what we expect for bulge ejecta, and so we believe these candidates are especially deserving of further study. We have supplemented this sample using our own radial velocities, developing an algorithm to use proper motions for optimizing candidate selection. This technique provides considerable improvement on the blind spectroscopic sample of SDSS, being able to identify candidates with an efficiency around 20 times better than a blind search.Comment: 13 pages, accepted for publication in Ap

Nearby Low-Mass Hypervelocity Stars

Hypervelocity stars are those that have speeds exceeding the escape speed and are hence unbound from the Milky Way. We investigate a sample of low-mass hypervelocity candidates obtained using data from the high-precision SDSS Stripe 82 catalogue, which we have combined with spectroscopy from the 200-inch Hale Telescope at Palomar Observatory. We find four good candidates, but without metallicities it is difficult to pin-down their distances and therefore total velocities. Our best candidate has a significant likelihood that it is escaping the Milky Way for a wide-range of metallicities.Comment: 5 pages; Contribution to proceedings for "The Milky Way Unravelled by Gaia" conference, Barcelona, Dec 201

Further evidence on the link between health care spending and health outcomes in England

This report describes results from research funded by the Health Foundation under its Quest for Quality and Improved Performance (QQuIP) initiative. It builds on our earlier report for the Health Foundation – The link between health care spending and health outcomes: evidence from English programme budgeting data – that took advantage of the availability of a major new dataset to examine the relationship between health care expenditure and mortality rates for two disease categories (cancer and circulation problems) across 300 English Primary Care Trusts. Our results are useful from a number of perspectives. Scientifically, they confirm our previous findings that health care has an important impact on health across a range of conditions, suggesting that those results were robust across programmes of care and across years. From a policy perspective, these results can help set priorities by informing resource allocation across a larger number of programmes of care. They also add further evidence to help NICE decide whether its current QALY threshold is at the right level.

Red Runaways: Hypervelocity Stars, Hills Ejecta and Other Outliers in the F-M Star Regime

In this paper we analyze a sample of metal-rich (>-0.8 dex) main sequence stars in the extended solar neighborhood, investigating kinematic outliers from the background population. The data, which are taken from the Sloan Digital Sky Survey, are kinematically profiled as a function of distance from the Galactic plane using full six dimensional phase space information. Each star is examined in the context of these kinematic profiles and likelihoods are assigned to quantify whether a star matches the underlying profile. Since some of these stars are likely to have been ejected from the disc, we trace back their orbits in order to determine potential ejection radii. We find that objects with low probability (i.e. `outliers') are typically more metal poor, faster and, most importantly, have a tendency to originate from the inner Galaxy compared to the underlying population. We also compose a sample of stars with velocities exceeding the local escape velocity. Although we do not discount that our sample could be contaminated by objects with spurious proper motions, a number of stars appear to have been ejected from the disc with exceptionally high velocities. Some of these are consistent with being ejected from the spiral arms and hence are a rich resource for further study. Finally we look at objects whose orbits are consistent with them being ejected at high speeds from the Galactic center. Of these objects we find that one, J135855.65+552538.19, is inconsistent with halo, bulge and disk kinematics and could plausibly have been ejected from the Galactic nucleus via a Hills mechanism.Comment: 17 Pages, 12 Figures, Accepted to A

The link between health care spending and health outcomes for the new English Primary Care Trusts

English programme budgeting data have yielded major new insights into the link between health care spending and health outcomes. This paper updates two recent studies that have used programme budgeting data for 295 Primary Care Trusts (PCTs) in England to examine the link between spending and outcomes for several programmes of care. We use the same economic model employed in the two previous studies. It focuses on a decision maker who must allocate a fixed budget across programmes of care so as to maximize social welfare given a health production function for each programme. Two equations – a health outcome equation and an expenditure equation – are estimated for each programme (data permitting). The two previous studies employed expenditure data for 2004/05 and 2005/06 for 295 health authorities and found that in several care programmes – cancer, circulation problems, respiratory problems, gastro-intestinal problems, trauma burns and injury, and diabetes – expenditure had the anticipated negative effect on the mortality rate. Each health outcome equation was used to estimate the marginal cost of a life year saved. In 2006/07 the number of PCTs in England was reduced to 152, largely through a series of mergers. In addition, several changes were made to the methods employed to construct the programme budgeting data. This paper employs updated budgeting and mortality data for the new 152 PCTs to re-estimate health production and expenditure functions, and also presents updated estimates of the marginal cost of a life year saved in each programme. Although there are some differences, the results obtained are broadly similar to those presented in our two previous studies.

The Link Between Health Care Spending and Health Outcomes: Evidence from English Programme Budgeting Data

This report describes preliminary results from research funded by the Health Foundation under its Quest for Quality and Improved Performance (QQuIP) initiative.

Value for money in the English NHS: Summary of the evidence

The extent to which the English National Health Service secures value for money for taxpayers has become a central issue of political and public debate. Questions include: how much expenditure growth has been made available to the NHS? on what has that money been spent? what improvements in the volume and quality of health care have been secured? and what are the implications for productivity? There has been a flurry of research activity designed to address these and similar questions. This report seeks to bring together this research in a concise format and draws some tentative conclusions about recent productivity changes in the NHS. It finds that there is considerable evidence of growth in both the volume and quality of NHS activity. However, this has not in general kept pace with the growth in expenditure. On most measures, therefore, NHS productivity is either static or declining. However, the report highlights a large number of unresolved methodological issues that make it hard to draw any definitive conclusions. We conclude that the measurement of NHS productivity change makes an important contribution to national debate. However, there remains considerable scope for improving both the data and the methods underlying current estimates.