Bianchi VIII Empty Futures

Using a qualitative analysis based on the Hamiltonian formalism and the orthonormal frame representation we investigate whether the chaotic behaviour which occurs close to the initial singularity is still present in the far future of Bianchi VIII models. We describe some features of the vacuum Bianchi VIII models at late times which might be relevant for studying the nature of the future asymptote of the general vacuum inhomogeneous solution to the Einstein field equations.Comment: 22 pages, no figures, Latex fil

Cosmic No Hair for Collapsing Universes

It is shown that all contracting, spatially homogeneous, orthogonal Bianchi cosmologies that are sourced by an ultra-stiff fluid with an arbitrary and, in general, varying equation of state asymptote to the spatially flat and isotropic universe in the neighbourhood of the big crunch singularity. This result is employed to investigate the asymptotic dynamics of a collapsing Bianchi type IX universe sourced by a scalar field rolling down a steep, negative exponential potential. A toroidally compactified version of M*-theory that leads to such a potential is discussed and it is shown that the isotropic attractor solution for a collapsing Bianchi type IX universe is supersymmetric when interpreted in an eleven-dimensional context.Comment: Extended discussion to include Kantowski-Sachs universe. In press, Classical and Quantum Gravit

Geographers out of place: institutions, (inter)disciplinarity and identity

Ten years ago, the decision was taken to close Brunel University’s Department of Geography and Earth Sciences and its undergraduate programmes. Since this time, most of the human geographers have remained at Brunel, but now work from beyond the boundaries of conventional academic Geography. In this paper we argue that this situation, which is not uncommon for geographers in the UK and elsewhere, has significant implications for both individuals and the discipline more broadly. Through our everyday experiences of interdisciplinary working, this paper reflects on what it means to be a geographer working outside of ‘Geography’. The paper examines the implications of this at three different yet related scales: the immediately personal scale in terms of identity and individual academic performance, the institutional scale and its organisation that can lead to the presence/ absence of academic subject areas, and then finally the disciplinary scale with its attendant spaces of knowledge generation, dissemination and protectionism. Our arguments are framed by neoliberal-led higher education changes and conceptualisations of institutions, (inter)disciplinarity and identity, and point to broader significances for the shape of the discipline

Integration of the Friedmann equation for universes of arbitrary complexity

An explicit and complete set of constants of the motion are constructed algorithmically for Friedmann-Lema\^{i}tre-Robertson-Walker (FLRW) models consisting of an arbitrary number of non-interacting species. The inheritance of constants of the motion from simpler models as more species are added is stressed. It is then argued that all FLRW models admit what amounts to a unique candidate for a gravitational epoch function (a dimensionless scalar invariant derivable from the Riemann tensor without differentiation which is monotone throughout the evolution of the universe). The same relations that lead to the construction of constants of the motion allow an explicit evaluation of this function. In the simplest of all models, the $\Lambda$CDM model, it is shown that the epoch function exists for all models with $\Lambda > 0$, but for almost no models with $\Lambda \leq 0$.Comment: Final form to appear in Physical Review D1

Housing Associations as institutional space: care and control in tenant welfare and training for work

Housing Associations operate at the community level between the state, market, and individual, and in the current political context of austerity, state roll-back, and welfare reform, have been increasingly tasked with focusing on the ‘welfare’ of their tenants. This has included ‘encouraging’ a trajectory of training for work for those tenants that are unemployed; a trajectory that is aimed at producing a certain type of ‘active’ and appropriate citizen-tenant at the local level, and which is based on the problematisation of those in social housing. This paper concentrates on how this trajectory is mobilised and implemented with an emphasis on how we conceptualise the dynamics and complexities of care and control that are central to this. HAs are framed as important locally-based institutions tasked with the local enactment of national policy imperatives. Through training-for-work initiatives, we explore how tenants are marked through the physical and conceptual spaces operated by HAs, and how HAs act as intermediaries between wider policy imperatives and localised, place-specific, and embodied interactions between tenants and housing professionals. We reflect on the dynamics of care and control involved in tenant engagement, with ‘care’ couched in terms of support and empathy but prompted by systems of control that classify and mark out tenants as in most ‘need’. We highlight the important role of HAs as fluid institutional sites of connection, emphasising the embodied and spatial regulatory relations through which careful control is enacted and practised

Homogeneous cosmologies with cosmological constant

Spatially homogeneous cosmological models with a positive cosmological constant are investigated, using dynamical systems methods. We focus on the future evolution of these models. In particular, we address the question whether there are models within this class that are de Sitter-like in the future, but are tilted.Comment: 10 pages, 13 eps-figures. Submitted to Phys. Rev.

Return to work interventions for chronic pain: a systematic review

Background:- Chronic pain (CP) remains the second commonest reason for being off work. Tertiary return to work (RTW) interventions aim to improve psychological and physical capacity amongst workers already off sick. Their effectiveness for workers with CP is unclear. Aims:- To explore which tertiary interventions effectively promote RTW for CP sufferers. Methods:- We searched eight databases for randomised controlled trials evaluating the effectiveness of tertiary RTW interventions for CP sufferers. We employed the Cochrane Risk of Bias (ROB) and methodological quality assessment tools for all included papers. We synthesised findings narratively. Meta-analysis was not possible due to heterogeneity of study characteristics. Results:- We included 16 papers pertaining to 13 trials. The types, delivery format and follow-up schedules of RTW interventions varied greatly. Most treatments were multidisciplinary, comprising psychological, physical and workplace elements. Five trials reported that tertiary interventions with multidisciplinary elements promoted RTW for workers with CP compared to controls. We gave a high ROB rating for one or more assessment criteria to three out of the five successful intervention trials. Two had medium and low risk elements across all categories. One compared different intensity multidisciplinary treatment and one comprised work-hardening with a job-coach. Seven trials found treatment effects for secondary outcomes but no RTW improvement. Conclusions:- There is no conclusive evidence to support any specific tertiary RTW intervention for workers with CP, but multidisciplinary efforts should be considered. Workers’ compensation is an important area for RTW policymakers to consider

Graded Majorana spinors

In many mathematical and physical contexts spinors are treated as Grassmann odd valued fields. We show that it is possible to extend the classification of reality conditions on such spinors by a new type of Majorana condition. In order to define this graded Majorana condition we make use of pseudo-conjugation, a rather unfamiliar extension of complex conjugation to supernumbers. Like the symplectic Majorana condition, the graded Majorana condition may be imposed, for example, in spacetimes in which the standard Majorana condition is inconsistent. However, in contrast to the symplectic condition, which requires duplicating the number of spinor fields, the graded condition can be imposed on a single Dirac spinor. We illustrate how graded Majorana spinors can be applied to supersymmetry by constructing a globally supersymmetric field theory in three-dimensional Euclidean space, an example of a spacetime where standard Majorana spinors do not exist.Comment: 16 pages, version to appear in J. Phys. A; AFK previously published under the name A. F. Schunc

BJP ASM Poster Abstracts 2018 - Tertiary return to work interventions for chronic pain: a systematic literature review

An abstract presented at British Journal of Pain's Annual Scientific Meeting. Five of the best abstracts submitted to the journal were presented during Plenary Session 7 on 2 May 2018 and also published in the journal

Gravitational Wave Propagation in Isotropic Cosmologies

We study the propagation of gravitational waves carrying arbitrary information through isotropic cosmologies. The waves are modelled as small perturbations of the background Robertson-Walker geometry. The perfect fluid matter distribution of the isotropic background is, in general, modified by small anisotropic stresses. For pure gravity waves, in which the perturbed Weyl tensor is radiative (i.e. type N in the Petrov classification), we construct explicit examples for which the presence of the anisotropic stress is shown to be essential and the histories of the wave-fronts in the background Robertson-Walker geometry are shear-free null hypersurfaces. The examples derived in this case are analogous to the Bateman waves of electromagnetic theory.Comment: 27 pages, accepted for publication in Phys.Rev.