Impulsive waves in the Nariai universe

A new class of exact solutions is presented which describes impulsive waves propagating in the Nariai universe. It is constructed using a six-dimensional embedding formalism adapted to the background. Due to the topology of the latter, the wave front consists of two non-expanding spheres. Special sub-classes representing pure gravitational waves (generated by null particles with an arbitrary multipole structure) or shells of null dust are analyzed in detail. Smooth isometries of the metrics are briefly discussed. Furthermore, it is shown that the considered solutions are impulsive members of a more general family of radiative Kundt spacetimes of type-II. A straightforward generalization to impulsive waves in the anti-Nariai and Bertotti-Robinson backgrounds is described. For a vanishing cosmological constant and electromagnetic field, results for well known impulsive pp-waves are recovered.Comment: 9 pages, 4 figures, REVTeX 4. v3: added Appendix B, revised references, minor changes in the text. To appear in Phys. Rev.

Ageing and Loneliness in England, c. 1500-1800

This is the author accepted manuscript.This chapter focuses on the responses of older people to loneliness in England, c.1500-1800. It is written on the premise that the conditions for loneliness existed in this period, and were experienced by some in old age. Yet because people in the early modern period understood that loneliness might bring negative consequences for mental, physical and material wellbeing, the elderly, either consciously or unconsciously, took steps to avoid loneliness. Beginning with an examination of the lives of the elderly poor, and then moving to consider the experiences of the middling sort and elite, we explore the economic, social and cultural practices that countered the threat of loneliness. The proposition is presented that many older people had a place in their families and communities, which meant that they remained socially integrated and valuable. Though individual experiences varied, a positive view of old age, as a time of opportunity, fulfilment, and creativity, was shared by many people in the early modern period

Design and construction of a power electronics based current injection unit to improve the accuracy of earthing system tests

The main method of testing earthing system performance involves the use of an off-frequency injection current produced by a voltage source. While this provides a sufficient testing tool for a number of systems, deficiencies such as noise susceptibility, restricted power capabilities and unstable current present significant challenges to earthing system testers. This paper outlines a novel application of inverter technology to this field. A review of control schemes was undertaken which resulted in the design of a robust method which is stable over a range of system conditions. A hardware prototype design that combined the benefits of a voltage source converter and the aforementioned control scheme was constructed. Furthermore, simulation and testing, in both the laboratory and on-site, demonstrates that the prototype outperforms the existing industry standard

Welfare, equality and social justice: Scottish independence and the dominant imaginings of the 'New' Scotland

This paper focuses on the extent to which issues of equality, social justice and social welfare have been mobilised in the most prominent imaginings of an independent Scotland. Since 2011 the SNP Scottish Government has repeatedly argued that any future independent Scotland will be characterised by a strong commitment to a distinctively Scottish social welfarism. This paper explores the main tenets of such claims noting that while the myths of Scottish distinctiveness in this respect have long been critiqued, they remain central to the visions of what Scottish society is, and what it could become. Drawing on specific framings and understandings of Scotland’s past, leading SNP politicians have made claims that a new Enlightenment in Scotland could act as a ‘beacon’ for progressive policy-making across the rest of the UK and Europe. This new Enlightenment would be underpinned by the ethics of equality and social justice and the market and economic growth would be servants rather than drivers of social change. In critically exploring these claims to Scottish distinctiveness, this paper focuses on a particular area of social policy, childcare. It is argued that policy-making, as well as the SNP vision for the future, focus on areas of concern that have a lineage back to Enlightenment ideas – investing in childhood as a means to make a better society. It highlights the challenges of combining a market-driven childcare strategy with a social investment approach. The paper aims to promote a critical engagement with the unfolding ‘imaginary’ of any independent (or more devolved) Scottish society, a society in which a globally competitive economy can deliver important socially just goals