102 research outputs found
A Higher Dimensional Stationary Rotating Black Hole Must be Axisymmetric
A key result in the proof of black hole uniqueness in 4-dimensions is that a
stationary black hole that is ``rotating''--i.e., is such that the stationary
Killing field is not everywhere normal to the horizon--must be axisymmetric.
The proof of this result in 4-dimensions relies on the fact that the orbits of
the stationary Killing field on the horizon have the property that they must
return to the same null geodesic generator of the horizon after a certain
period, . This latter property follows, in turn, from the fact that the
cross-sections of the horizon are two-dimensional spheres. However, in
spacetimes of dimension greater than 4, it is no longer true that the orbits of
the stationary Killing field on the horizon must return to the same null
geodesic generator. In this paper, we prove that, nevertheless, a higher
dimensional stationary black hole that is rotating must be axisymmetric. No
assumptions are made concerning the topology of the horizon cross-sections
other than that they are compact. However, we assume that the horizon is
non-degenerate and, as in the 4-dimensional proof, that the spacetime is
analytic.Comment: 24 pages, no figures, v2: footnotes and references added, v3:
numerous minor revision
On the `Stationary Implies Axisymmetric' Theorem for Extremal Black Holes in Higher Dimensions
All known stationary black hole solutions in higher dimensions possess
additional rotational symmetries in addition to the stationary Killing field.
Also, for all known stationary solutions, the event horizon is a Killing
horizon, and the surface gravity is constant. In the case of non-degenerate
horizons (non-extremal black holes), a general theorem was previously
established [gr-qc/0605106] proving that these statements are in fact generally
true under the assumption that the spacetime is analytic, and that the metric
satisfies Einstein's equation. Here, we extend the analysis to the case of
degenerate (extremal) black holes. It is shown that the theorem still holds
true if the vector of angular velocities of the horizon satisfies a certain
"diophantine condition," which holds except for a set of measure zero.Comment: 30pp, Latex, no figure
The agency of liminality: army wives in the DR Congo and the tactical reversal of militarization
The inherently unstable boundaries between military and civilian worlds have emerged as a main object of study within the field of critical military studies. This article sheds light on the (re)production of these boundaries by attending to a group that rarely features in the debates on the military/civilian divide: army wives in a ‘non-Northern’ context, more specifically the Democratic Republic of the Congo (DRC). Drawing upon the ‘analytical toolbox’ of governmentality, we explore how civilian and military positionalities are called upon, articulated and subverted in the governing and self-governing of Congolese army wives. We show the decisive importance of these wives’ civilian-military ‘in betweenness’ both in efforts to govern them and in their exercise of agency, in particular
The inherently unstable boundaries between military and civilian worlds have emerged as a main object of study within the field of critical military studies. This article sheds light on the (re)production of these boundaries by attending to a group that rarely features in the debates on the military/civilian divide: army wives in a ‘non-Northern’ context, more specifically the Democratic Republic of the Congo (DRC). Drawing upon the ‘analytical toolbox’ of governmentality, we explore how civilian and military positionalities are called upon, articulated, and subverted in the governing and self-governing of Congolese army wives. We show the decisive importance of these wives’ civilian–military ‘in-betweenness’ both in efforts to govern them and in their exercise of agency, in particular the ways in which they ‘tactically reverse’ militarization. The article also demonstrates the dispersed nature of the governing arrangements surrounding army wives, highlighting the vital role of ‘the civilian’ as well as the ‘agency of those being militarized’ within processes of militarization. By foregrounding the relevance of studying Congolese army wives and their militarization with an analytical toolbox often reserved for so called ‘advanced militaries/societies’, and by revealing numerous similarities between the Congolese and ‘Northern’ contexts, the article also sets out to counter the Euro/US-centrism and ‘theoretical discrimination’ that mark present-day (critical) military studies
Clinical effectiveness of health visitor training in psychologically informed approaches for depression in postnatal women: pragmatic cluster randomised trial in primary care
Objective - To evaluate benefits for postnatal women of two psychologically informed interventions by health visitors.
Design - Prospective cluster trial randomised by general practice, with 18 month follow-up.
Setting - 101 general practices in Trent, England.
Participants - 2749 women allocated to intervention, 1335 to control.
Intervention - Health visitors (n=89 63 clusters) were trained to identify depressive symptoms at six to eight weeks postnatally using the Edinburgh postnatal depression scale (EPDS) and clinical assessment and also trained in providing psychologically informed sessions based on cognitive behavioural or person centred principles for an hour a week for eight weeks. Health visitors in the control group (n=49 38 clusters) provided usual care.
Main outcome measures - Score ≥12 on the Edinburgh postnatal depression scale at six months. Secondary outcomes were mean Edinburgh postnatal depression scale, clinical outcomes in routine evaluation-outcome measure (CORE-OM), state-trait anxiety inventory (STAI), SF-12, and parenting stress index short form (PSI-SF) scores at six, 12, 18 months.
Results - 4084 eligible women consented and 595 women had a six week EPDS score ≥12. Of these, 418 had EPDS scores available at six weeks and six months. At six months, 34% women (93/271) in the intervention group and 46% (67/147) in the control group had an EPDS score ≥12. The odds ratio for score ≥12 at six months was 0.62 (95% confidence interval 0.40 to 0.97, P=0.036) for women in the intervention group compared with women in the control group. After adjustment for covariates, the odds ratio was 0.60 (0.38 to 0.95, P=0.028). At six months, 12.4% (234/1880) of all women in the intervention group and 16.7% (166/995) of all women in the control group had scores ≥12 (0.67, 0.51 to 0.87, P=0.003). Benefit for women in the intervention group with a six week EPDS score ≥12 and for all women was maintained at 12 months postnatally. There was no differential benefit for either psychological approach over the other.
Conclusion - Training health visitors to assess women, identify symptoms of postnatal depression, and deliver psychologically informed sessions was clinically effective at six and 12 months postnatally compared with usual care.
Trial registration - ISRCTN92195776
Assistive technology design and development for acceptable robotics companions for ageing years.
A new stream of research and development responds to changes in life expectancy across the world. It includes technologies which enhance well-being of individuals, specifically for older people. The ACCOMPANY project focuses on home companion technologies and issues surrounding technology development for assistive purposes. The project responds to some overlooked aspects of technology design, divided into multiple areas such as empathic and social human-robot interaction, robot learning and memory visualisation, and monitoring persons’ activities at home. To bring these aspects together, a dedicated task is identified to ensure technological integration of these multiple approaches on an existing robotic platform, Care-O-Bot®3 in the context of a smart-home environment utilising a multitude of sensor arrays. Formative and summative evaluation cycles are then used to assess the emerging prototype towards identifying acceptable behaviours and roles for the robot, for example role as a butler or a trainer, while also comparing user requirements to achieved progress. In a novel approach, the project considers ethical concerns and by highlighting principles such as autonomy, independence, enablement, safety and privacy, it embarks on providing a discussion medium where user views on these principles and the existing tension between some of these principles, for example tension between privacy and autonomy over safety, can be captured and considered in design cycles and throughout project developments
Seasonal size variation in the predatory cladoceran Bythotrephes cederstroemii in Lake Michigan
1.  Dry weight, body length and spine length were measured for the exotic cladoceran Bythotrephes cederstroemii collected from offshore and inshore stations in southeastern Lake Michigan. Average dry weight of each developmental stage exhibited seasonal variation by a factor of more than 5. 2.  Mean dry weight of Bythotrephes was closely correlated with water temperature. Contrary to the inverse relationship between water temperature and body size frequently observed for other invertebrates, the dry weight of Bythotrephes increased at higher ambient temperatures. 3.  No significant correlation was observed between abundances of major zooplankton taxa and the dry weight of Bythotrephes . An indirect effect of temperature on prey consumption may cause seasonal variation in dry weight of Bythotrephes in Lake Michigan. 4.  Distances between adjacent pairs of barbs, added to the caudal spine with each moult, are significantly shorter in Bythotrephes which produce resting eggs. Less material investment in the exoskeleton of sexually reproducing females was observed in favour of growth and reproduction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74641/1/j.1365-2427.1994.tb00842.x.pd
Gastroesophageal reflux and antacid therapy in IPF: analysis from the Australia IPF Registry
BACKGROUND AND OBJECTIVE:Gastroesophageal reflux disease (GORD) is highly prevalent in idiopathic pulmonary fibrosis (IPF) and may play a role in its pathogenesis. Recent IPF treatment guidelines suggest that all patients with IPF be considered for antacid therapy. However, emerging evidence suggests that antacid therapy does not improve IPF patient outcomes and may increase the risk of pulmonary infection. METHODS:Using prospectively collected data from the Australian IPF Registry including use of antacid therapy, GORD diagnosis and GORD symptoms, the relationship of these GORD variables to survival and disease progression was assessed. The severity of GORD symptoms using the frequency scale for symptoms of GORD (FSSG) and its relationships to outcomes was also assessed for the first time in an IPF cohort. RESULTS:Five hundred eighty-seven (86%) of the 684 patients in the Australian IPF Registry were eligible for inclusion. Patients were mostly male (69%), aged 71.0 ± 8.5 years with moderate disease (FVC 81.7 ± 21.5%; DLco 48.5 ± 16.4%). Most patients were taking antacids (n = 384; 65%), though fewer had a diagnosis of GORD (n = 243, 41.4%) and typical GORD symptoms were even less common (n = 171, 29.1%). The mean FSSG score was 8.39 ± 7.45 with 43% (n = 251) having a score > 8. Overall, there was no difference in survival or disease progression, regardless of antacid treatment, GORD diagnosis or GORD symptoms. CONCLUSIONS:Neither the use of antacid therapy nor the presence of GORD symptoms affects longer term outcomes in IPF patients. This contributes to the increasing evidence that antacid therapy may not be beneficial in IPF patients and that GORD directed therapy should be considered on an individual basis to treat the symptoms of reflux.Helen E. Jo, Tamera J. Corte, Ian Glaspole, Christopher Grainge, Peter M. A. Hopkins ... Peter A. Bampton ... et al
Two-neutron and core-excited states in Pb 210: Tracing E3 collectivity and evidence for a new β -decaying isomer in Tl 210
Yrast and near-yrast levels up to an I=17 spin value and a 6-MeV excitation energy have been delineated in the "two-neutron" Pb210 nucleus following deep-inelastic reactions involving Pb208 targets and a number of heavy-ion beams at energies ∼25% above the Coulomb barrier. The level scheme was established on the basis of multifold prompt and delayed coincidence relationships measured with the Gammasphere array. In addition to the previously known states, many new levels were identified. For most of the strongly populated states, spin-parity assignments are proposed on the basis of angular distributions. The reinvestigation of the ν(g9/2)2, 8+ isomeric decay results in the firm identification of the low-energy E2 transitions involved in the 8+→6+→4+ cascade, and in a revised 6+ level half-life of 92(10) ns, nearly a factor of 2 longer than previously measured. Among the newly identified states figure spin I=4-10 levels associated with the νg9/2i11/2 multiplet, as well as yrast states involving νg9/2j15/2, νi11/2j15/2, and ν(j15/2)2 neutron couplings. The highest-spin excitations are understood as 1p-1h core excitations and the yrast population is found to be fragmented to the extent that levels of spin higher than I=17 could not be reached. Four E3 transitions are present in the Pb210 yrast decay; three of these involve the g9/2→j15/2 octupole component, as reflected in the 21(2) and >10 Weisskopf unit enhancements of the B(E3) rates of the first two. The fourth, 16+→13-E3 transition corresponds to the 3- core octupole excitation built on the νi11/2j15/2 state, in analogy to a similar E3 coupling to the νj15/2 level in Pb209. Shell-model calculations performed for two-neutron states and 1p-1h Pb208 core excitations are in good agreement with the data. Evidence was found for the existence of a hitherto unknown high-spin β-decaying isomer in Tl210. Shell-model calculations of the Tl210 levels suggest the possibility of a 11+ long-lived, β-decaying state, and the delayed yields observed in various reactions fit rather well with a Tl210 assignment
Quantitative computed tomography predicts outcomes in idiopathic pulmonary fibrosis
First published: 25 July 2022Background and objective: Prediction of disease course in patients with progressive pulmonary fibrosis remains challenging. The purpose of this study was to assess the prognostic value of lung fibrosis extent quantified at computed tomography (CT) using data-driven texture analysis (DTA) in a large cohort of well-characterized patients with idiopathic pulmonary fibrosis (IPF) enrolled in a national registry. Methods: This retrospective analysis included participants in the Australian IPF Registry with available CT between 2007 and 2016. CT scans were analysed using the DTA method to quantify the extent of lung fibrosis. Demographics, longitudinal pulmonary function and quantitative CT metrics were compared using descriptive statistics. Linear mixed models, and Cox analyses adjusted for age, gender, BMI, smoking history and treatment with anti-fibrotics were performed to assess the relationships between baseline DTA, pulmonary function metrics and outcomes. Results: CT scans of 393 participants were analysed, 221 of which had available pulmonary function testing obtained within 90 days of CT. Linear mixed-effect modelling showed that baseline DTA score was significantly associated with annual rate of decline in forced vital capacity and diffusing capacity of carbon monoxide. In multivariable Cox proportional hazard models, greater extent of lung fibrosis was associated with poorer transplant-free survival (hazard ratio [HR] 1.20, p < 0.0001) and progression-free survival (HR 1.14, p < 0.0001). Conclusion: In a multi-centre observational registry of patients with IPF, the extent of fibrotic abnormality on baseline CT quantified using DTA is associated with outcomes independent of pulmonary function.Stephen M. Humphries, John A. Mackintosh, Helen E. Jo, Simon L. F. Walsh, Mario Silva, Lucio Calandriello, Sally Chapman, Samantha Ellis, Ian Glaspole, Nicole Goh, Christopher Grainge, Peter M. A. Hopkins, Gregory J. Keir, Yuben Moodley, Paul N. Reynolds, E. Haydn Walters, David Baraghoshi, Athol U. Wells, David A. Lynch, Tamera J. Cort
Detection of interstellar oxidaniumyl: Abundant H2O+ towards the star-forming regions DR21, Sgr B2, and NGC6334
Aims. We identify a prominent absorption feature at 1115 GHz, detected in first HIFI spectra towards high-mass star-forming regions, and interpret
its astrophysical origin.
Methods. The characteristic hyperfine pattern of the H2O+ ground-state rotational transition, and the lack of other known low-energy transitions in
this frequency range, identifies the feature as H2O+ absorption against the dust continuum background and allows us to derive the velocity profile
of the absorbing gas. By comparing this velocity profile with velocity profiles of other tracers in the DR21 star-forming region, we constrain the
frequency of the transition and the conditions for its formation.
Results. In DR21, the velocity distribution of H2O+ matches that of the [Cii] line at 158 μm and of OH cm-wave absorption, both stemming
from the hot and dense clump surfaces facing the Hii-region and dynamically affected by the blister outflow. Diffuse foreground gas dominates
the absorption towards Sgr B2. The integrated intensity of the absorption line allows us to derive lower limits to the H2O+ column density of
7.2 × 1012 cm−2 in NGC 6334, 2.3 × 1013 cm−2 in DR21, and 1.1 × 1015 cm−2 in Sgr B2
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