258 research outputs found
Analysis of the feasibility of an experiment to measure carbon monoxide in the atmosphere
The feasibility of measuring atmospheric carbon monoxide from a remote platform using the correlation interferometry technique was considered. It has been determined that CO data can be obtained with an accuracy of 10 percent using this technique on the first overtone band of CO at 2.3 mu. That band has been found to be much more suitable than the stronger fundamental band at 4.6 mu. Calculations for both wavelengths are presented which illustrate the effects of atmospheric temperature profiles, inversion layers, ground temperature and emissivity, CO profile, reflectivity, and atmospheric pressure. The applicable radiative transfer theory on which these calculations are based is described together with the principles of the technique
Intense Electromagnetic Outbursts from Collapsing Hypermassive Neutron Stars
We study the gravitational collapse of a magnetized neutron star using a
novel numerical approach able to capture both the dynamics of the star and the
behavior of the surrounding plasma. In this approach, a fully general
relativistic magnetohydrodynamics implementation models the collapse of the
star and provides appropriate boundary conditions to a force-free model which
describes the stellar exterior. We validate this strategy by comparing with
known results for the rotating monopole and aligned rotator solutions and then
apply it to study both rotating and non-rotating stellar collapse scenarios,
and contrast the behavior with what is obtained when employing the
electrovacuum approximation outside the star. The non-rotating electrovacuum
collapse is shown to agree qualitatively with a Newtonian model of the
electromagnetic field outside a collapsing star. We illustrate and discuss a
fundamental difference between the force-free and electrovacuum solutions,
involving the appearance of large zones of electric-dominated field in the
vacuum case. This provides a clear demonstration of how dissipative
singularities appear generically in the non-linear time-evolution of force-free
fluids. In both the rotating and non-rotating cases, our simulations indicate
that the collapse induces a strong electromagnetic transient. In the case of
sub-millisecond rotation, the magnetic field experiences strong winding and the
transient carries much more energy. This result has important implications for
models of gamma-ray bursts.Comment: 28 pages, 20 figures (quality lowered to reduce sizes). Improved
initial data and matching condition results in a lower, but still important,
energy emission. Added appendix with a discussion on effects of transition
laye
Barriers to positive mental health in a young offenders institution: A qualitative study
Objective: To explore the barriers to positive mental health in a group of young offenders.
Design A qualitative approach was used to provide insight into the ways in which mental health for young offenders is experienced and managed. Setting A Young Offenders Institute (YOI) accommodating males aged between 18 and 21 years.
Method: Participants were recruited voluntarily using posters. Twelve offenders participated in focus groups and an additional three interviews were carried out with individuals who felt uncomfortable in the focus group situation.
Results: Participants stressed that feelings in a YOI could not be shared due to the masculine ethos that had been created on the wings. Listener services were reported to be ineffective for support because using them would show weakness and vulnerability to other prisoners. Visiting time was the main highlight in the routine for most young offenders; however, leaving family and friends was difficult. In dealing with these emotions young offenders would use coping mechanisms, including acts of aggression to vent built-up frustrations. The issue of prison staff and their effect on mental health was raised by all offenders involved in the research. Unanimously, it was suggested that there are both excellent prison officers who engage with the prisoners, and staff who abuse their power and treat prisoners disrespectfully.
Conclusion: Promoting mental health is not the principle business of a YOI. However, this research has generated some issues for consideration for governors and those working within this setting
Dual harm: an exploration of the presence and characteristics for dual violence and self-harm behaviour in prison
Objective: The study aimed to quantify the rate of dual-harm behaviour in comparison with sole self-harm or assault rates; with an analysis of the distinguishing features.
Method: Official data on in-prison incidents, demographic and offending information was analysed for two prisons in England.
Results: Proportions of up to 42% of offenders who assault others in prison will also engage in self-harm and vice versa. Dual harm prisoners will engage in a broader and greater frequency of prison incidents than either sole group; with dual-harm prisoners reflecting greater proportions of damage to property and fire setting. Connectedly, dual harm prisoners receive a far higher rate of adjudication. There were no differences in their time in prison, presence of serious violent offences or for the dual harm prisoners whether the first incident was self-harm or violence. An index offence of drug supply was less likely in the dual-harm group, with minor violence slightly more likely in longer sentence prisoners.
Implications: In-prison behaviour can assist in the identification of prisoners at dual-risk of harm. Greater inclusion of in-prison behaviour and awareness of dual-harm in research methodologies may assist in improving risk management. A wider use of joint risk assessment and single case management approach is suggested for prisoners with dual-harm profile
On the Nonlinear Stability of Asymptotically Anti-de Sitter Solutions
Despite the recent evidence that anti-de Sitter spacetime is nonlinearly
unstable, we argue that many asymptotically anti-de Sitter solutions are
nonlinearly stable. This includes geons, boson stars, and black holes. As part
of our argument, we calculate the frequencies of long-lived gravitational
quasinormal modes of AdS black holes in various dimensions. We also discuss a
new class of asymptotically anti-de Sitter solutions describing noncoalescing
black hole binaries.Comment: 26 pages. 5 figure
Black holes in the Brans-Dicke-Maxwell theory
The black hole solutions in the higher dimensional Brans-Dicke-Maxwell theory
are investigated. We find that the presence of the nontrivial scalar field
depends on the spacetime dimensions (D). When D=4, the solution corresponds to
the Reissner-Nordstr\"{o}m black hole with a constant scalar field. In higher
dimensions (D>4), one finds the charged black hole solutions with the
nontrivial scalar field. The thermal properties of the charged black holes are
discussed and the reason why the nontrivial scalar field exists are explained.
Also the solutions for higher dimensional Brans-Dicke theory are given for
comparison.Comment: Revtex, 5 pages, no figures, contents were rewritten and new
references were adde
Reflections on undertaking the Probation Qualifying Framework scheme during the transforming rehabilitation changes
This article reflects upon the author’s experience of undertaking the PQF (Probation Qualifying Framework) training scheme during the chaotic period of Transforming Rehabilitation. The author asserts that the uncertainty and precarious nature of the changes were detrimental to an effective learning environment, which ultimately promoted a practice culture of punitiveness and control and did not allow learners the space to be skilful and confident practitioners, comfortable working autonomously. Furthermore, the author contends there is an emerging culture within the NPS (National Probation Service) increasingly fostered on ‘risk management’, which is reflected in the vocational nature of PQF training and is contributing towards a widening cultural gap that is emerging between the community rehabilitation companies and NPS
Reversing Blood Flows Act through klf2a to Ensure Normal Valvulogenesis in the Developing Heart
Heart valve anomalies are some of the most common congenital heart defects, yet neither the genetic nor the epigenetic forces guiding heart valve development are well understood. When functioning normally, mature heart valves prevent intracardiac retrograde blood flow; before valves develop, there is considerable regurgitation, resulting in reversing (or oscillatory) flows between the atrium and ventricle. As reversing flows are particularly strong stimuli to endothelial cells in culture, an attractive hypothesis is that heart valves form as a developmental response to retrograde blood flows through the maturing heart. Here, we exploit the relationship between oscillatory flow and heart rate to manipulate the amount of retrograde flow in the atrioventricular (AV) canal before and during valvulogenesis, and find that this leads to arrested valve growth. Using this manipulation, we determined that klf2a is normally expressed in the valve precursors in response to reversing flows, and is dramatically reduced by treatments that decrease such flows. Experimentally knocking down the expression of this shear-responsive gene with morpholine antisense oligonucleotides (MOs) results in dysfunctional valves. Thus, klf2a expression appears to be necessary for normal valve formation. This, together with its dependence on intracardiac hemodynamic forces, makes klf2a expression an early and reliable indicator of proper valve development. Together, these results demonstrate a critical role for reversing flows during valvulogenesis and show how relatively subtle perturbations of normal hemodynamic patterns can lead to both major alterations in gene expression and severe valve dysgenesis
AMR, stability and higher accuracy
Efforts to achieve better accuracy in numerical relativity have so far
focused either on implementing second order accurate adaptive mesh refinement
or on defining higher order accurate differences and update schemes. Here, we
argue for the combination, that is a higher order accurate adaptive scheme.
This combines the power that adaptive gridding techniques provide to resolve
fine scales (in addition to a more efficient use of resources) together with
the higher accuracy furnished by higher order schemes when the solution is
adequately resolved. To define a convenient higher order adaptive mesh
refinement scheme, we discuss a few different modifications of the standard,
second order accurate approach of Berger and Oliger. Applying each of these
methods to a simple model problem, we find these options have unstable modes.
However, a novel approach to dealing with the grid boundaries introduced by the
adaptivity appears stable and quite promising for the use of high order
operators within an adaptive framework
Probation staff experiences of managing suicidal and self-harming service users
The current study sought to explore the impact of suicidal behaviours on probation staff, in relation to their experiences of working with Probation service users who have carried out suicide, attempted suicide or self-harm. Thirteen in-depth interviews were carried out with probation staff who had direct contact with Probation service users in one Probation area, and had varying degrees of experience of managing suicidal or self-injurious service users. These were analysed using Thematic Analysis and five themes were identified. Findings indicate that staff felt that suicide and self-harm by service users are serious issues which need to be recognised and dealt with in an effective yet compassionate manner. However not attending the Suicide Prevention Training or lack of experience was perceived as restricting their ability to know how to deal with these individuals, and offer support. Furthermore, staff were emotionally affected by these incidents and it is recommend that they should continue to be provided with access to appropriate support services after an incident
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