19,994 research outputs found
Observing Lense-Thirring Precession in Tidal Disruption Flares
When a star is tidally disrupted by a supermassive black hole (SMBH), the
streams of liberated gas form an accretion disk after their return to
pericenter. We demonstrate that Lense-Thirring precession in the spacetime
around a rotating SMBH can produce significant time evolution of the disk
angular momentum vector, due to both the periodic precession of the disk and
the nonperiodic, differential precession of the bound debris streams. Jet
precession and periodic modulation of disk luminosity are possible
consequences. The persistence of the jetted X-ray emission in the Swift
J164449.3+573451 flare suggests that the jet axis was aligned with the spin
axis of the SMBH during this event.Comment: 4 pages, 4 figures. Accepted for publication in Physical Review
Letters. Minor changes made to match proof
Cosmic Variance In the Transparency of the Intergalactic Medium After Reionization
Following the completion of cosmic reionization, the mean-free-path of
ionizing photons was set by a population of Ly-limit absorbers. As the
mean-free-path steadily grew, the intensity of the ionizing background also
grew, thus lowering the residual neutral fraction of hydrogen in ionization
equilibrium throughout the diffuse intergalactic medium (IGM). Ly-alpha photons
provide a sensitive probe for tracing the distribution of this residual
hydrogen at the end of reionization. Here we calculate the cosmic variance
among different lines-of-sight in the distribution of the mean Ly-alpha optical
depths. We find fractional variations in the effective post-reionization
optical depth that are of order unity on a scale of ~100 co-moving Mpc, in
agreement with observations towards high-redshift quasars. Significant
contributions to these variations are provided by the cosmic variance in the
density contrast on the scale of the mean-free-path for ionizing photons, and
by fluctuations in the ionizing background induced by delayed or enhanced
structure formation. Cosmic variance results in a highly asymmetric
distribution of transmission through the IGM, with fractional fluctuations in
Ly-alpha transmission that ar larger than in Ly-beta transmission.Comment: 7 pages 3 figures. Replaced with version accepted for publication in
Ap
The barriers to and enablers of providing reasonably adjusted health services to people with intellectual disabilities in acute hospitals: evidence from a mixed-methods study.
OBJECTIVE: To identify the factors that promote and compromise the implementation of reasonably adjusted healthcare services for patients with intellectual disabilities in acute National Health Service (NHS) hospitals.
DESIGN: A mixed-methods study involving interviews, questionnaires and participant observation (July 2011-March 2013).
SETTING: Six acute NHS hospital trusts in England.
METHODS: Reasonable adjustments for people with intellectual disabilities were identified through the literature. Data were collected on implementation and staff understanding of these adjustments.
RESULTS: Data collected included staff questionnaires (n=990), staff interviews (n=68), interviews with adults with intellectual disabilities (n=33), questionnaires (n=88) and interviews (n=37) with carers of patients with intellectual disabilities, and expert panel discussions (n=42). Hospital strategies that supported implementation of reasonable adjustments did not reliably translate into consistent provision of such adjustments. Good practice often depended on the knowledge, understanding and flexibility of individual staff and teams, leading to the delivery of reasonable adjustments being haphazard throughout the organisation. Major barriers included: lack of effective systems for identifying and flagging patients with intellectual disabilities, lack of staff understanding of the reasonable adjustments that may be needed, lack of clear lines of responsibility and accountability for implementing reasonable adjustments, and lack of allocation of additional funding and resources. Key enablers were the Intellectual Disability Liaison Nurse and the ward manager.
CONCLUSIONS: The evidence suggests that ward culture, staff attitudes and staff knowledge are crucial in ensuring that hospital services are accessible to vulnerable patients. The authors suggest that flagging the need for specific reasonable adjustments, rather than the vulnerable condition itself, may address some of the barriers. Further research is recommended that describes and quantifies the most frequently needed reasonable adjustments within the hospital pathways of vulnerable patient groups, and the most effective organisational infrastructure required to guarantee their use, together with resource implications
High-Redshift Galaxies: Their Predicted Size and Surface Brightness Distributions and Their Gravitational Lensing Probability
Direct observations of the first generation of luminous objects will likely
become feasible over the next decade. The advent of the Next Generation Space
Telescope (NGST) will allow imaging of numerous galaxies and mini-quasars at
redshifts z>5. We apply semi-analytic models of structure formation to estimate
the rate of multiple imaging of these sources by intervening gravitational
lenses. Popular CDM models for galaxy formation yield a lensing optical depth
of about 1% for sources at redshift 10. The expected slope of the luminosity
function of the early sources implies an additional magnification bias of about
5, bringing the fraction of lensed sources at z=10 to about 5%. We estimate the
angular size distribution of high-redshift disk galaxies and find that most of
them are more extended than the resolution limit of NGST, roughly 0.06
arcseconds. We also show that there is only a modest redshift evolution in the
mean surface brightness of galaxies at z>2. The expected increase by 1-2 orders
of magnitude in the number of resolved sources on the sky, due to observations
with NGST, will dramatically improve upon the statistical significance of
existing weak lensing measurements. We show that, despite this increase in the
density of sources, confusion noise from z>2 galaxies is expected to be small
for NGST observations.Comment: 27 pages, 8 PostScript figures (of which two are new), revised
version accepted for Ap
Ammonia Concentrations of Musts of Different Grape Cultivars and Vineyards in the Stellenbosch Area
The ammonia concentrations of a large number of loads of grapes from different farms and of different cultivars were measured. Varietal differences were noted and statistical verifications made. Nine different cultivars were investigated. The average mean ammonia values for the cultivars varied from 54,9 to 148,l mg/(. Where enough loads from individual vineyards or growers were available, statistical differences were demonstrated. The conditions, treatment, and soil of the vines were shown to be reflected in the extremes by the juice ammonia concentrations. The use of these data is suggested as a means of assessing the vineyard's relative worth for winemaking purposes
Impact of a theoretically based sex education programme (SHARE) delivered by teachers on NHS registered conceptions and terminations: final results of cluster randomised trial
<b>Objective</b>: To assess the impact of a theoretically based sex education programme (SHARE) delivered by teachers compared with conventional education in terms of conceptions and terminations registered by the NHS.
Design Follow-up of cluster randomised trial 4.5 years after intervention.
<b>Setting</b>: NHS records of women who had attended 25 secondary schools in east Scotland.
<b>Participants</b>: 4196 women (99.5% of those eligible).
<b>Intervention</b>: SHARE programme (intervention group) v existing sex education (control group).
<b>Main outcome measure</b>: NHS recorded conceptions and terminations for the achieved sample linked at age 20.
<b>Results</b>: In an "intention to treat" analysis there were no significant differences between the groups in registered conceptions per 1000 pupils (300 SHARE v 274 control; difference 26, 95% confidence interval –33 to 86) and terminations per 1000 pupils (127 v 112; difference 15, –13 to 42) between ages 16 and 20.
<b>Conclusions</b>: This specially designed sex education programme did not reduce conceptions or terminations by age 20 compared with conventional provision. The lack of effect was not due to quality of delivery. Enhancing teacher led school sex education beyond conventional provision in eastern Scotland is unlikely to reduce terminations in teenagers
Extent of regretted sexual intercourse among young teenagers in Scotland: a cross sectional survey
No abstract available
The BCS gap equation for spin-polarized fermions
We study the BCS gap equation for a Fermi gas with unequal population of
spin-up and spin-down states. For , with the
temperature and the chemical potential difference, the question of
existence of non-trivial solutions can be reduced to spectral properties of a
linear operator, similar to the unpolarized case studied previously in
\cite{FHNS,HHSS,HS}. For the phase diagram is more
complicated, however. We derive upper and lower bounds for the critical
temperature, and study their behavior in the small coupling limit.Comment: 23 pages, 1 figur
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