The 2-10 keV XRB dipole and its cosmological implications

The hard X-ray (>2 keV) emission of the local and distant Universe as observed with the HEAO1-A2 experiment is reconsidered in the context of large scale cosmic structure. Using all-sky X-ray samples of AGN and galaxy clusters we remove the dominant local X-ray flux from within a redshift of ~ 0.02. We evaluate the dipolar and higher order harmonic structure in 4 X-ray colours. The estimated dipole anisotropy of the unresolved flux appears to be consistent with a combination of the Compton-Getting effect due to the Local Group motion (dipole amplitude Delta = 0.0042) and remaining large scale structure (0.0023 <~ Delta <~ 0.0085), in good agreement with the expectations of Cold Dark Matter models. The observed anisotropy does however also suggest a non-negligible Galactic contribution which is more complex than current, simple models of >2 keV Galactic X-ray emission. Comparison of the soft and hard colour maps with a harmonic analysis of the 1.5 keV ROSAT all-sky data qualitatively suggests that at least a third of the faint, unresolved ~ 18 deg scale structure in the HEAO1-A2 data may be Galactic in origin. However, the effect on measured flux dipoles is small (<~3%). We derive an expression for dipole anisotropy and acceleration and demonstrate how the dipole anisotropy of the distant X-ray frame can constrain the amplitude of bulk motions of the universe. From observed bulk motions over a local ~ 50 Mpc/h radius volume we determine 0.14 <~ Omega^0.6/b_x(0) <~ 0.59.Comment: 39 pages, Revised version accepted ApJ Main Journal, 3 new Figures + additional tex

Bayes and health care research.

Bayes’ rule shows how one might rationally change one’s beliefs in the light of evidence. It is the foundation of a statistical method called Bayesianism. In health care research, Bayesianism has its advocates but the dominant statistical method is frequentism. There are at least two important philosophical differences between these methods. First, Bayesianism takes a subjectivist view of probability (i.e. that probability scores are statements of subjective belief, not objective fact) whilst frequentism takes an objectivist view. Second, Bayesianism is explicitly inductive (i.e. it shows how we may induce views about the world based on partial data from it) whereas frequentism is at least compatible with non-inductive views of scientific method, particularly the critical realism of Popper. Popper and others detail significant problems with induction. Frequentism’s apparent ability to avoid these, plus its ability to give a seemingly more scientific and objective take on probability, lies behind its philosophical appeal to health care researchers. However, there are also significant problems with frequentism, particularly its inability to assign probability scores to single events. Popper thus proposed an alternative objectivist view of probability, called propensity theory, which he allies to a theory of corroboration; but this too has significant problems, in particular, it may not successfully avoid induction. If this is so then Bayesianism might be philosophically the strongest of the statistical approaches. The article sets out a number of its philosophical and methodological attractions. Finally, it outlines a way in which critical realism and Bayesianism might work together. </p

The X-ray absorber of PKS2126-158

BeppoSAX observed the z=3.27 quasar PKS2126-158 on 1999 May 24-28 when its 2-10keV and 0.1-2.5keV fluxes were 1.1E-11 and 4.4E-12 cgs respectively, a factor of 2 higher than in all previous ROSAT and ASCA observations and 40% higher than in two more recent Chandra and XMM-Newton observations. The shortest detected rest frame variability timescale is of a few months, comparable to the causal timescale associated to an emission region of ~10 Schwarzschild radii around a few 1E10 solar masses black hole. The source is detected with a signal to noise ratio S/N>=3 up to ~50 keV, 215 keV rest frame. The BeppoSAX observations confirm the presence of low energy absorption along the line of sight, independent on the continuum model adopted, at high confidence level. Despite the limited spectral resolution of the BeppoSAX LECS and MECS it is possible to put constraints on different absorption and continuum models, but not to unambiguously determine the redshift of the absorber. If the absorber is not significantly ionized the BeppoSAX data do prefer an absorber at z<=2.7. Strong and complex metal line systems along the line of sight to PKS2126-158 have been found at z=0.6631 and at 2.64<z<2.82. They could well be associated to the X-ray absorption. Conversely, an ionized (``warm'') absorber at the quasar redshift provides a good fit only if the iron abundance is smaller than ~0.3 solar, while that of the other elements is fixed to the solar value.Comment: A&A in pres

Community Policing: Broken Windows, Community Building, and Satisfaction with the Police

The concept of community policing dominates the law enforcement profession today. One would be hard pressed to find an advertisement for a police chief’s position that does not require a thorough understanding of this method of policing. Like the Kansas City preventive patrol experiment and the Rand report on the criminal investigation process, the call for community policing has led to dramatic changes in the way that police carry out their responsibilities. In spite of its popularity, there have been a number of challenges to community policing from social scientists who are particularly concerned about the ‘broken windows’ model of policing. These challenges have not been received well by the law enforcement community, which argues that sociologists are wedded to the idea that crime is caused by the structural features of capitalist society, including economic injustice, racism, and poverty. The purpose of this article is to bridge the gap between these two positions. Yes, there is a place for community policing, and, yes, social problems do contribute to crime. The article starts by reviewing the development of community policing in the United States. An analysis of the theoretical constructs that support community policing then follows. Finally, we argue that there is sound theoretical evidence to support community policing, particularly those programmes that improve citizen satisfaction with the manner in which police carry out their responsibilities

Discoverer - Making commercial satellite operations in very low earth orbit a reality

DISCOVERER is a €5.7M European Commission funded Horizon 2020 project developing technologies to enable commercially-viable sustained-operation of satellites in very low Earth orbits. Why operate closer to the Earth? For communications applications latency is significantly reduced and link budgets improved, and for remote sensing improved link budgets allow higher resolution or smaller instruments, all providing cost benefits. In addition, all applications benefit from increased launch mass to lower altitudes, whilst end-of-life removal is ensured due to the increased atmospheric drag. However, this drag must also be minimised and compensated for. One of the key technologies being developed by DISCOVERER are materials that encourage specular reflection of the residual atmosphere at these altitudes. Combined with appropriate geometric designs these can significantly reduce drag, provide usable lift for aerodynamic attitude and orbit control, and improve the collection efficiency of aerodynamic intakes for atmosphere breathing electric propulsion systems, all of which are being developed as part of DISCOVERER. The paper provides highlights from the developments to date, and the potential for a new class of aerodynamic commercial satellites operating at altitudes below the International Space Station

Concepts and Applications of Aerodynamic Attitude and Orbital Control for Spacecraft in Very Low Earth Orbit

Spacecraft operations below 450km, namely Very Low Earth Orbit (VLEO), can offer significant advantages over traditional low Earth orbits, for example enhanced ground resolution for Earth observation, improved communications latency and link budget, or improved signal-to-noise ratio. Recently, these lower orbits have begun to be exploited as a result of technology development, particularly component miniaturisation and cost-reduction, and concerns over the increasing debris population in commercially exploited orbits. However, the high cost of orbital launch and challenges associated with atmospheric drag, causing orbital decay and eventually re-entry are still a key barrier to their wider use for large commercial and civil spacecraft. Efforts to address the impact of aerodynamic drag are being sought through the development of novel drag-compensation propulsion systems and identification of materials which can reduce aerodynamic drag by specularly reflecting the incident gas. However, the presence of aerodynamic forces can also be utilised to augment or improve spacecraft operations at these very low altitudes by providing the capability to perform coarse pointing control and trim or internal momentum management for example. This paper presents concepts for the advantageous use of spacecraft aerodynamics developed as part of DISCOVERER, a Horizon 2020 funded project with the aim to revolutionise Earth observation satellite operations in VLEO. The combination of novel spacecraft geometries and use of aerodynamic control methods are explored, demonstrating the potential for a new generation of Earth observation satellites operating at lower altitudes

Efficacy of a strategy for implementing a guideline for the control of cardiovascular risk in a primary healthcare setting: the SIRVA2 study a controlled, blinded community intervention trial randomised by clusters

This work describes the methodology used to assess a strategy for implementing clinical practice guidelines (CPG) for cardiovascular risk control in a health area of Madrid

Cascade testing in Familial Hypercholesterolaemia: how should family members be contacted?

Cascade testing or screening provides an important mechanism for identifying people at risk of a genetic condition. For some autosomal dominant conditions, such as Familial Hpercholesterolaemia (FH), identifying relatives allows for significant health-affecting interventions to be administered, which can extend a person’s life expectancy significantly. However, cascade screening is not without ethical implications. In this paper, we examine one ethically contentious aspect of cascade screening programmes, namely the alternative methods by which relatives of a proband can be contacted. Should the proband be responsible for contacting his or her family members, or should the screening programme contact family members directly? We argue that direct contact is an ethically justifiable method of contact tracing in cascade screening for FH. Not only has this method of contact already been utilised without adverse effects, an examination of the ethical arguments against it shows these are unsubstantiated. We describe several criteria which, if met, will allow an appropriate balance to be struck between maximising the efficiency of family tracing and respecting the interests of probands and their relatives. Keywords Cascade genetic screening; cascade testing; confidentiality; autonomy; genetics; ethics; guidelines; familial hypercholesterolaemi

Evaluation of a multi-disciplinary back pain rehabilitation programme—individual and group perspectives

To evaluate the impact of a multi-disciplinary back pain rehabilitation programme using a combination of individual and group change data. A total of 261 consecutive patients attending an assessment session for the back pain rehabilitation programme completed the SF-36 health survey questionnaire. The patients were requested to complete the questionnaires again at programme completion and at the 6-month follow-up. The Reliable Change Index was used to define 'clinical significance' in terms of the assessment of individual change. Half of those patients considered to be suitable for the programme subsequently completed it. In group terms, non-completers scored lower than completers on all SF-36 scales. Statistically significant improvements were evident for those completing the programme (all scales at P < 0.000), with improvement maintained at follow-up. In individual terms, 'clinical significance' was exceeded most frequently in the Physical Functioning and Role Physical scales. Whilst some participants lost previous improvements between completion and follow-up, others improved over this same time period. The majority of those completing the programme showed improvement in at least one scale. Adding assessment of individual change to traditional group change measures provides greater insight into the impact a rehabilitation programme has upon participants' quality of life. Whilst the programme is clearly effective for those who complete it, work is required to limit post-programme deterioration and improve uptak