The reverberation signatures of rotating disc winds in active galactic nuclei

The broad emission lines (BELs) in active galactic nuclei (AGN) respond to ionizing continuum variations. The time and velocity dependence of their response depends on the structure of the broad-line region: its geometry, kinematics and ionization state. Here, we predict the reverberation signatures of BELs formed in rotating accretion disc winds. We use a Monte Carlo radiative transfer and ionization code to predict velocity-delay maps for representative high- (C$~IV$) and low-ionization (H$\alpha$) emission lines in both high- and moderate-luminosity AGN. Self-shielding, multiple scattering and the ionization structure of the outflows are all self-consistently taken into account, while small-scale structure in the outflow is modelled in the micro-clumping approximation. Our main findings are: (1) The velocity-delay maps of smooth/micro-clumped outflows often contain significant negative responses. (2)~The reverberation signatures of disc wind models tend to be rotation dominated and can even resemble the classic "red-leads-blue" inflow signature. (3) Traditional "blue-leads-red" outflow signatures can usually only be observed in the long-delay limit. (4) Our models predict lag-luminosity relationships similar to those inferred from observations, but systematically underpredict the observed centroid delays. (5) The ratio between "virial product" and black hole mass predicted by our models depends on viewing angle. Our results imply that considerable care needs to be taken in interpreting data obtained by observational reverberation mapping campaigns. In particular, basic signatures such as "red-leads-blue", "blue-leads-red" and "blue and red vary jointly" are not always reliable indicators of inflow, outflow or rotation. This may help to explain the perplexing diversity of such signatures seen in observational campaigns to date.Comment: 15 pages, 17 figures, 2 tables. Accepted by MNRAS 20/7/201

Physisorption controls the conformation and density of states of an adsorbed porphyrin

Conformational changes caused by adsorption can dramatically affect a molecule’s properties. Despite extensive study, however, the exact mechanisms underpinning conformational switching are often unclear. Here we show that the conformation of a prototypical flexible molecule, the freebase tetra(4-bromophenyl) porphyrin, adsorbed on Cu(111), depends critically on its precise adsorption site and that, remarkably, large conformational changes are dominated by van der Waals interactions between the molecule and the substrate surface. A combination of scanning probe microscopy, single-molecule manipulation, DFT with dispersion density functional theory, and molecular dynamics simulations show that van der Waals forces drive significant distortions of the molecular architecture so that the porphyrin can adopt one of two low-energy conformations. We find that adsorption driven by van der Waals forces alone is capable of causing large shifts in the molecular density of states, despite the apparent absence of chemical interactions. These findings highlight the essential role that van der Waals forces play in determining key molecular properties

Designing and implementing interventions to change clinicians' practice in the management of uncomplicated malaria: lessons from Cameroon.

BACKGROUND: Effective case management of uncomplicated malaria is a fundamental pillar of malaria control. Little is known about the various steps in designing interventions to accompany the roll out of rapid diagnostic tests (RDTs) and artemisinin-based combination therapy (ACT). This study documents the process of designing and implementing interventions to change clinicians' practice in the management of uncomplicated malaria. METHODS: A literature review combined with formative quantitative and qualitative research were carried out to determine patterns of malaria diagnosis and treatment and to understand how malaria and its treatment are enacted by clinicians. These findings were used, alongside a comprehensive review of previous interventions, to identify possible strategies for changing the behaviour of clinicians when diagnosing and treating uncomplicated malaria. These strategies were discussed with ministry of health representatives and other stakeholders. Two intervention packages - a basic and an enhanced training were outlined, together with logic model to show how each was hypothesized to increase testing for malaria, improve adherence to test results and increase appropriate use of ACT. The basic training targeted clinicians' knowledge of malaria diagnosis, rapid diagnostic testing and malaria treatment. The enhanced training included additional modules on adapting to change, professionalism and communicating effectively. Modules were delivered using small-group work, card games, drama and role play. Interventions were piloted, adapted and trainers were trained before final implementation. RESULTS: Ninety-six clinicians from 37 health facilities in Bamenda and Yaounde sites attended either 1-day basic or 3-day enhanced training. The trained clinicians then trained 632 of their peers at their health facilities. Evaluation of the training revealed that 68% of participants receiving the basic and 92% of those receiving the enhanced training strongly agreed that it is not appropriate to prescribe anti-malarials to a patient if they have a negative RDT result. CONCLUSION: Formative research was an important first step, and it was valuable to engage stakeholders early in the process. A logic model and literature reviews were useful to identify key elements and mechanisms for behaviour change intervention. An iterative process with feedback loops allowed appropriate development and implementation of the intervention. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01350752

Organization theory and military metaphor: time for a reappraisal?

A ‘conventional’ use of military metaphor would use it to convey attributes such as hierarchical organization, vertical communication and limited autonomy. This is often used in contrast to a looser form of organization based on the metaphor of the network. However, this article argues that military practice is more complex, with examples of considerable autonomy within the constraints of central direction. It is suggested that not only might this be a more useful metaphor for many contemporary organizations, but also that simplistic uses of military metaphor divert our attention away from the functions that management hierarchies play. The discussion is embedded within a critical realist account of metaphor, arguing for both its value and the need for its further development

Managerial Work in a Practice-Embodying Institution - The role of calling, the virtue of constancy

What can be learned from a small scale study of managerial work in a highly marginal and under-researched working community? This paper uses the ‘goods-virtues-practices-institutions’ framework to examine the managerial work of owner-directors of traditional circuses. Inspired by MacIntyre’s arguments for the necessity of a narrative understanding of the virtues, interviews explored how British and Irish circus directors accounted for their working lives. A purposive sample was used to select subjects who had owned and managed traditional touring circuses for at least 15 years, a period in which the economic and reputational fortunes of traditional circuses have suffered badly. This sample enabled the research to examine the self-understanding of people who had, at least on the face of it, exhibited the virtue of constancy. The research contributes to our understanding of the role of the virtues in organizations by presenting evidence of an intimate relationship between the virtue of constancy and a ‘calling’ work orientation. This enhances our understanding of the virtues that are required if management is exercised as a domain-related practice

Differences in antiretroviral scale up in three South African provinces: the role of implementation management

BACKGROUND: South Africa's antiretroviral programme is governed by defined national plans, establishing treatment targets and providing funding through ring-fenced conditional grants. However, in terms of the country's quasi-federal constitution, provincial governments bear the main responsibility for provision of health care, and have a certain amount of autonomy and therefore choice in the way their HIV/AIDS programmes are implemented. METHODS: The paper is a comparative case study of the early management of ART scale up in three South African provincial governments--Western Cape, Gauteng and Free State--focusing on both operational and strategic dimensions. Drawing on surveys of models of ART care and analyses of the policy process conducted in the three provinces between 2005 and 2007, as well as a considerable body of grey and indexed literature on ART scale up in South Africa, it draws links between implementation processes and variations in provincial ART coverage (low, medium and high) achieved in the three provinces. RESULTS: While they adopted similar chronic disease care approaches, the provinces differed with respect to political and managerial leadership of the programme, programme design, the balance between central standardisation and local flexibility, the effectiveness of monitoring and evaluation systems, and the nature and extent of external support and programme partnerships. CONCLUSIONS: This case study points to the importance of sub-national programme processes and the influence of factors other than financing or human resource capacity, in understanding intervention scale up

Do reverberation mapping analyses provide an accurate picture of the broad line region?

WM acknowledges the University of Southampton‘s Institute for Complex Systems Simulation and the Engineering and Physical Sciences Research Council for the PhD student that funded his research. CK and NSH acknowledge support by the Science and Technology Facilities Council grant ST/M001326/1. JHM is supported by the Science and Technology Facilities Council under grant ST/N000919/1. KH acknowledges support from STFC grant ST/R000824/1.Reverberation mapping (RM) is a powerful approach for determining the nature of the broad-line region (BLR) in active galactic nuclei. However, inferring physical BLR properties from an observed spectroscopic time series is a difficult inverse problem. Here, we present a blind test of two widely used RM methods: MEMEcho (developed by Horne) and CARAMEL (developed by Pancoast and collaborators). The test data are simulated spectroscopic time series that track the Hα emission line response to an empirical continuum light curve. The underlying BLR model is a rotating, biconical accretion disc wind, and the synthetic spectra are generated via self-consistent ionization and radiative transfer simulations. We generate two mock data sets, representing Seyfert galaxies and QSOs. The Seyfert model produces a largely negative response, which neither method can recover. However, both fail “gracefully”, neither generating spurious results. For the QSO model both CARAMEL and expert interpretation of MEMEchoś output both capture the broadly annular, rotation-dominated nature of the line-forming region, though MEMEcho analysis overestimates its size by 50%, but CARAMEL is unable to distinguish between additional inflow and outflow components. Despite fitting individual spectra well, the CARAMEL velocity-delay maps and RMS line profiles are strongly inconsistent with the input data. Finally, since the Hα line-forming region is rotation dominated, neither method recovers the disc wind nature of the underlying BLR model. Thus considerable care is required when interpreting the results of RM analyses in terms of physical models.PostprintPeer reviewe

Basic or enhanced clinician training to improve adherence to malaria treatment guidelines: a cluster-randomised trial in two areas of Cameroon

Background The scale-up of malaria rapid diagnostic tests (RDTs) is intended to improve case management of fever and targeting of artemisinin-based combination therapy. Habitual presumptive treatment has hampered these intentions, suggesting a need for strategies to support behaviour change. We aimed to assess the introduction of RDTs when packaged with basic or enhanced clinician training interventions in Cameroon. Methods We did a three-arm, stratifi ed, cluster-randomised trial at 46 public and mission health facilities at two study sites in Cameroon to compare three approaches to malaria diagnosis. Facilities were randomly assigned by a computer program in a 9:19:19 ratio to current practice with microscopy (widely available, used as a control group); RDTs with a basic (1 day) clinician training intervention; or RDTs with an enhanced (3 days) clinician training intervention. Patients (or their carers) and fi eldworkers who administered surveys to obtain outcome data were masked to study group assignment. The primary outcome was the proportion of patients treated in accordance with WHO malaria treatment guidelines, which is a composite indicator of whether patients were tested for malaria and given appropriate treatment consistent with the test result. All analyses were by intention to treat. This study is registered at ClinicalTrials. gov, number NCT01350752. Findings The study took place between June 7 and Dec 14, 2011. The analysis included 681 patients from nine facilities in the control group, 1632 patients from 18 facilities in the basic-training group, and 1669 from 19 facilities in the enhanced-training group. The proportion of patients treated in accordance with malaria guidelines did not improve with either intervention; the adjusted risk ratio (RR) for basic training compared with control was 1·04 (95% CI 0·53–2·07; p=0·90), and for enhanced training compared with control was 1·17 (0·61–2·25; p=0·62). Inappropriate use of antimalarial drugs after a negative test was reduced from 84% (201/239) in the control group to 52% (413/796) in the basic-training group (unadjusted RR 0·63, 0·28–1·43; p=0·25) and to 31% (232/759) in the enhanced-training group (0·29, 0·11–0·77; p=0·02). Interpretation Enhanced clinician training, designed to translate knowledge into prescribing practice and improve quality of care, has the potential to halve overtreatment in public and mission health facilities in Cameroon. Basic training is unlikely to be suffi cient to support the behaviour change required for the introduction of RDTs

A cost-effectiveness analysis of provider interventions to improve health worker practice in providing treatment for uncomplicated malaria in Cameroon: a study protocol for a randomized controlled trial

BACKGROUND: Governments and donors all over Africa are searching for sustainable, affordable and cost-effective ways to improve the quality of malaria case management. Widespread deficiencies have been reported in the prescribing and counselling practices of health care providers treating febrile patients in both public and private health facilities. Cameroon is no exception with low levels of adherence to national guidelines, the frequent selection of non-recommended antimalarials and the use of incorrect dosages. This study evaluates the effectiveness and cost-effectiveness of introducing two different provider training packages, alongside rapid diagnostic tests (RDTs), designed to equip providers with the knowledge and practical skills needed to effectively diagnose and treat febrile patients. The overall aim is to target antimalarial treatment better and to facilitate optimal use of malaria treatment guidelines. METHODS/DESIGN: A 3-arm stratified, cluster randomized trial will be conducted to assess whether introducing RDTs with provider training (basic or enhanced) is more cost-effective than current practice without RDTs, and whether there is a difference in the cost effectiveness of the provider training interventions. The primary outcome is the proportion of patients attending facilities that report a fever or suspected malaria and receive treatment according to malaria guidelines. This will be measured by surveying patients (or caregivers) as they exit public and mission health facilities. Cost-effectiveness will be presented in terms of the primary outcome and a range of secondary outcomes, including changes in provider knowledge. Costs will be estimated from a societal and provider perspective using standard economic evaluation methodologies. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00981877