On the consistency of neutron-star radius measurements from thermonuclear bursts

The radius of neutron stars can in principle be measured via the normalisation of a blackbody fitted to the X-ray spectrum during thermonuclear (type-I) X-ray bursts, although few previous studies have addressed the reliability of such measurements. Here we examine the apparent radius in a homogeneous sample of long, mixed H/He bursts from the low-mass X-ray binaries GS 1826-24 and KS 1731-26. The measured blackbody normalisation (proportional to the emitting area) in these bursts is constant over a period of up to 60s in the burst tail, even though the flux (blackbody temperature) decreased by a factor of 60-75% (30-40%). The typical rms variation in the mean normalisation from burst to burst was 3-5%, although a variation of 17% was found between bursts observed from GS 1826-24 in two epochs. A comparison of the time-resolved spectroscopic measurements during bursts from the two epochs shows that the normalisation evolves consistently through the burst rise and peak, but subsequently increases further in the earlier epoch bursts. The elevated normalisation values may arise from a change in the anisotropy of the burst emission, or alternatively variations in the spectral correction factor, f_c, of order 10%. Since burst samples observed from systems other than GS 1826-24 are more heterogeneous, we expect that systematic uncertainties of at least 10% are likely to apply generally to measurements of neutron-star radii, unless the effects described here can be corrected for.Comment: 9 pages, 6 figures; accepted by Ap

Innovative's Electronic Resource Management as catalyst for change at Glasgow University Library

In March 2003 Glasgow University Library joined with Innovative and several other Innovative customers to develop a new Electronic Resource Management (ERM) module. This paper will outline the ways in which the development and implementation of ERM has acted as a catalyst and facilitator for further enhancements and developments in the area of e-journals at Glasgow University Library

One tale of property, in my own words

The power of the State to alter the conditions of land use through planning laws continues to attract theorisation at the possible intersection between planning and property. As planning laws become more complex, and by needs responsive to environmental degradation - including the consequences of climate change - landowners will arguably suffer loss of market value of their land despite broader community benefit. This article analyses the contention that land planning regulation is itself property - a claim made by Paul Babie in this journal in 2016. It does so in four parts, focusing on the law’s own construction of both real property and planning permissions. It analyses the nature, content and source of the estate in fee simple in Queensland, followed by analysis of Penner’s ‘bundle of rights’ argument to ascertain whether planning laws might be comprehended within this conception of property. It goes on to assess planning permissions in terms of Honore’s incidents of property before establishing the nature, content and source of planning rights. Finally, it clarifies how planning law responds to climate change, suggesting that downstream liabilities rather than front-line environmental protection is at stake. In conclusion, it posits a conceptualisation of property alternative to that of Babie

Big data: A case study of disruption and government power

Although it is part of core government business to collect information about its citizens, ‘big data’ has increased the scale, speed and complexity of data collection and use to such an extent that it is arguably qualitatively different from the record-keeping that has gone before it. Big data represents a radical shift in the balance of power between State and citizen. This article argues that embedding big data in government operations masks its deployment as enhancing government power, rather than simply facilitating execution of government activities. In other words, big data is ‘disruptive’ technology that calls for the examination of the limits of government power. To illustrate this argument, this article examines a selection of recent case studies of attempts by the Australian government to deploy big data as a tool of governance. It identifies the risk to the citizen inherent in the use of big data, to justify review of the bounds of government power in the face of rapid technological change. </jats:p

The experiences of male gay business owners in the UK

The article reports on a qualitative study of the motivations for and experiences of business ownership amongst 11 male gay entrepreneurs in the UK. Included in this analysis is a comparison with issues identified throughout the extant literature for other minority groups, particularly women. Corroborating previous studies, the male-gay-owned firms studied here were concentrated in the service sector and catered to diverse markets. While homophobia is reported in both employment and business ownership it is indirect and implicit rather than direct discrimination or harassment and is not cited as an entrepreneurial motivator. The findings are of importance insofar as they provide new knowledge and consequently, further our understanding of the diverse phenomena of entrepreneurship. Further, the article illustrates that heteronormativity and the gendered nature of most employment contexts also extends to the entrepreneurship domain. </jats:p

On the Geometry and Mass of Static, Asymptotically AdS Spacetimes, and the Uniqueness of the AdS Soliton

We prove two theorems, announced in hep-th/0108170, for static spacetimes that solve Einstein's equation with negative cosmological constant. The first is a general structure theorem for spacetimes obeying a certain convexity condition near infinity, analogous to the structure theorems of Cheeger and Gromoll for manifolds of non-negative Ricci curvature. For spacetimes with Ricci-flat conformal boundary, the convexity condition is associated with negative mass. The second theorem is a uniqueness theorem for the negative mass AdS soliton spacetime. This result lends support to the new positive mass conjecture due to Horowitz and Myers which states that the unique lowest mass solution which asymptotes to the AdS soliton is the soliton itself. This conjecture was motivated by a nonsupersymmetric version of the AdS/CFT correspondence. Our results add to the growing body of rigorous mathematical results inspired by the AdS/CFT correspondence conjecture. Our techniques exploit a special geometric feature which the universal cover of the soliton spacetime shares with familiar ``ground state'' spacetimes such as Minkowski spacetime, namely, the presence of a null line, or complete achronal null geodesic, and the totally geodesic null hypersurface that it determines. En route, we provide an analysis of the boundary data at conformal infinity for the Lorentzian signature static Einstein equations, in the spirit of the Fefferman-Graham analysis for the Riemannian signature case. This leads us to generalize to arbitrary dimension a mass definition for static asymptotically AdS spacetimes given by Chru\'sciel and Simon. We prove equivalence of this mass definition with those of Ashtekar-Magnon and Hawking-Horowitz.Comment: Accepted version, Commun Math Phys; Added Remark IV.3 and supporting material dealing with non-uniqueness arising from choice of special cycle on the boundary at infinity; 2 new citations added; LaTeX 27 page

Existence of CMC Cauchy surfaces and spacetime splitting

In this paper, we review results on the existence (and nonexistence) of constant mean curvature spacelike hypersurfaces in the cosmological setting, and discuss the connection to the spacetime splittng problem. It is a pleasure to dedicate this paper to Robert Bartnik, who has made fundamental contributions to this area.Comment: 16 page