Collision velocity of dust grains in self-gravitating protoplanetary discs

We have conducted the first comprehensive numerical investigation of the relative velocity distribution of dust particles in self-gravitating protoplanetary discs with a view to assessing the viability of planetesimal formation via direct collapse in such environments. The viability depends crucially on the large sizes that are preferentially collected in pressure maxima produced by transient spiral features (Stokes numbers, St ∼ 1); growth to these size scales requires that collision velocities remain low enough that grain growth is not reversed by fragmentation. We show that, for a single-sized dust population, velocity driving by the disc's gravitational perturbations is only effective for St > 3, while coupling to the gas velocity dominates otherwise. We develop a criterion for understanding this result in terms of the stopping distance being of the order of the disc scaleheight. Nevertheless, the relative velocities induced by differential radial drift in multi-sized dust populations are too high to allow the growth of silicate dust particles beyond St ∼ 10− 2 or 10−1 (10 cm to m sizes at 30 au), such Stokes numbers being insufficient to allow concentration of solids in spiral features. However, for icy solids (which may survive collisions up to several 10 m s−1), growth to St ∼ 1 (10 m size) may be possible beyond 30 au from the star. Such objects would be concentrated in spiral features and could potentially produce larger icy planetesimals/comets by gravitational collapse. These planetesimals would acquire moderate eccentricities and remain unmodified over the remaining lifetime of the disc.This work has been supported by the DISCSIM project, grant agreement 341137 funded by the European Research Council under ERC-2013-ADG and has used the DIRAC Shared Memory Processing and DiRAC Data Analytic systems at the University of Cambridge. The DIRAC Shared Memory Processing system is operated by the COSMOS Project at the Department of Applied Mathematics and Theoretical Physics and was funded by BIS National E-infrastructure capital grant ST/J005673/1, STFC capital grant ST/H008586/1. The DiRAC Data Analytic system was funded by BIS National E-infrastructure capital grant ST/J005673/1 and STFC capital grant ST/H008586/1. Both systems are on behalf of the STFC DiRAC HPC Facility (www.dirac.ac.uk), funded by the STFC DiRAC Operations grant ST/K00333X/1.This is the final version of the article. It first appeared from Oxford University Press via http://dx.doi.org/10.1093/mnras/stw48

Interventions for behaviour change and self-management in stroke secondary prevention: protocol for an overview of reviews

Background: Stroke secondary prevention guidelines recommend medication prescription and adherence, activeeducation and behavioural counselling regarding lifestyle risk factors. To impact on recurrent vascular events, positivebehaviour/s must be adopted and sustained as a lifestyle choice, requiring theoretically informed behaviour changeand self-management interventions. A growing number of systematic reviews have addressed complex interventionsin stroke secondary prevention. Differing terminology, inclusion criteria and overlap of studies between reviews makesthe mechanism/s that affect positive change difficult to identify or replicate clinically. Adopting a two-phase approach,this overview will firstly comprehensively summarise systematic reviews in this area and secondly identify andsynthesise primary studies in these reviews which provide person-centred, theoretically informed interventions forstroke secondary prevention.Methods: An overview of reviews will be conducted using a systematic search strategy across the CochraneDatabase of Systematic Reviews, PubMed and Epistomonikas. Inclusion criteria: systematic reviews where thepopulation comprises individuals post-stroke or TIA and where data relating to person-centred risk reductionare synthesised for evidence of efficacy when compared to standard care or no intervention. Primary outcomes of interestinclude mortality, recurrent stroke and other cardiovascular events. In phase 1, two reviewers will independently (1) assessthe eligibility of identified reviews for inclusion; (2) rate the quality of included reviews using the ROBIS tool; (3) identifyunique primary studies and overlap between reviews; (4) summarise the published evidence supporting person-centredbehavioural change and self-management interventions in stroke secondary prevention and (5) identify evidence gaps inthis field. In phase 2, two independent reviewers will (1) examine person-centred, primary studies in each review usingthe Template for Intervention Description and Replication (TIDieR checklist), itemising, where present, theoreticalframeworks underpinning interventions; (2) group studies employing theoretically informed interventions by theintervention delivered and by the outcomes reported (3) apply GRADE quality of evidence for each interventionby outcome/s identified from theoretically informed primary studies. Disagreement between reviewers at eachprocess stage will be discussed and a third reviewer consulted.Discussion: This overview will comprehensively bring together the best available evidence supporting person-centred,stroke secondary prevention strategies in an accessible format, identifying current knowledge gaps

Multiple Satellite Observations of Cloud Cover in Extratropical Cyclones

Using cloud observations from NASA Moderate Resolution Imaging Spectroradiometer, Multiangle Imaging Spectroradiometer, and CloudSat-CALIPSO, composites of cloud fraction in southern and northern hemisphere extratropical cyclones are obtained for cold and warm seasons between 2006 and 2010, to assess differences between these three data sets, and between summer and winter cyclones. In both hemispheres and seasons, over the open ocean, the cyclone-centered cloud fraction composites agree within 5% across the three data sets, but behind the cold fronts, or over sea ice and land, the differences are much larger. To supplement the data set comparison and learn more about the cyclones, we also examine the differences in cloud fraction between cold and warm season for each data set. The difference in cloud fraction between cold and warm season southern hemisphere cyclones is small for all three data sets, but of the same order of magnitude as the differences between the data sets. The cold-warm season contrast in northern hemisphere cyclone cloud fractions is similar for all three data sets: in the warm sector, the cold season cloud fractions are lower close to the low, but larger on the equator edge than their warm season counterparts. This seasonal contrast in cloud fraction within the cyclones warm sector seems to be related to the seasonal differences in moisture flux within the cyclones. Our analysis suggests that the three different data sets can all be used confidently when studying the warm sector and warm frontal zone of extratropical cyclones but caution should be exerted when studying clouds in the cold sector

Diagnosing Warm Frontal Cloud Formation in a GCM: A Novel Approach Using Conditional Subsetting

This study analyzes characteristics of clouds and vertical motion across extratropical cyclone warm fronts in the NASA Goddard Institute for Space Studies general circulation model. The validity of the modeled clouds is assessed using a combination of satellite observations from CloudSat, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E), and the NASA Modern-Era Retrospective Analysis for Research and Applications (MERRA) reanalysis. The analysis focuses on developing cyclones, to test the model's ability to generate their initial structure. To begin, the extratropical cyclones and their warm fronts are objectively identified and cyclone-local fields are mapped into a vertical transect centered on the surface warm front. To further isolate specific physics, the cyclones are separated using conditional subsetting based on additional cyclone-local variables, and the differences between the subset means are analyzed. Conditional subsets are created based on 1) the transect clouds and 2) vertical motion; 3) the strength of the temperature gradient along the warm front, as well as the storm-local 4) wind speed and 5) precipitable water (PW). The analysis shows that the model does not generate enough frontal cloud, especially at low altitude. The subsetting results reveal that, compared to the observations, the model exhibits a decoupling between cloud formation at high and low altitudes across warm fronts and a weak sensitivity to moisture. These issues are caused in part by the parameterized convection and assumptions in the stratiform cloud scheme that are valid in the subtropics. On the other hand, the model generates proper covariability of low-altitude vertical motion and cloud at the warm front and a joint dependence of cloudiness on wind and PW

Interagency collaboration models for people with mental ill health in contact with the police: a systematic scoping review

Objective: To identify existing evidence on inter-agency collaboration between law enforcement, emergency services, statutory services and third sector agencies regarding people with mental ill-health. Design: Systematic scoping review. Scoping reviews map particular research areas to identify research gaps. Data sources and eligibility: ASSIA, CENTRAL, the Cochrane Library databases, Criminal Justice Abstracts, ERIC, Embase, MEDLINE, PsycINFO, PROSPERO and Social Care Online and Social Sciences Citation Index, were searched up to 2017, as were grey literature and hand searches. Eligible articles were empirical evaluations or descriptions of models of inter-agency collaboration between the police and other agencies. Study appraisal and synthesis: Screening and data extraction were undertaken independently by two researchers. Arksey’s framework was used to collate and map included studies. Results: One hundred and twenty-five studies were included. The majority of articles were of descriptions of models (28%), mixed methods evaluations of models (18%) and single service evaluations (14%). The most frequently reported outcomes (52%) were ‘organisational or service level outcomes’ (e.g. arrest rates). Most articles (53%) focused on adults with mental ill-health, whilst others focused on adult offenders with mental ill-health (17.4%). Thirteen models of inter-agency collaboration were described, each involving between 2-13 agencies. Frequently reported models were ‘pre-arrest diversion’ of people with mental ill-health (34%), ‘co-response’ involving joint response by police officers paired with mental health professionals (28.6%) and ‘jail diversion’ following arrest (23.8%). Conclusions: We identified 13 different inter-agency collaboration models catering for a range of mental health related interactions. All but one of these models involved the police and mental health services or professionals. Several models have sufficient literature to warrant full systematic reviews of their effectiveness, while others need robust evaluation, by RCT where appropriate. Future evaluations should focus on health related outcomes and the impact on key stakeholders

Undertaking a randomised controlled trial in the police setting : methodological and practical challenges

BACKGROUND: There has been an increased drive towards Evidence Based Policing in recent years. Unlike in other public sector services, such as health and education, randomised controlled trials in the police setting are relatively rare. This paper discusses some of the methodological and practical challenges of conducting a randomised controlled trial in the police setting in the UK, based on our experience of the Connect trial. This pragmatic, cluster-randomised controlled trial investigated the effectiveness of a face-to-face training intervention for frontline officers in comparison to routine training. The primary outcome was the number of incidents which resulted in a police response reported to North Yorkshire Police control room in a 1-month period up to 6 months after delivery of training. MAIN TEXT: The methodological and practical challenges that we experienced whilst conducting the Connect trial are discussed under six headings: establishing the unit of randomisation; population of interest and sample size; co-production of evidence; time frame; outcomes; and organisational issues. CONCLUSION: Recommendations on the conduct of future randomised controlled trials in the police setting are made. To understand the context in which research is undertaken, collaboration between police and academia is needed and police officers should be embedded within trial management groups. Engagement with police data analysts to understand what data is available and facilitate obtaining trial data is also recommended. Police forces may wish to review their IT systems and recording practices. Pragmatic trials are encouraged and time frames need to allow for trial set-up and obtaining relevant ethical approvals. TRIAL REGISTRATION: ISRCTN Registry, ID: ISRCTN11685602 . Retrospectively registered on 13 May 2016

Shoujo versus Seinen? Address and reception in Puella Magi Madoka Magica (2011)

This article uses the Japanese television anime series Puella Magi Madoka Magica (2011) as a case study through which to problematise the relationship between two prominent traditions within children’s literature criticism: narratology, with its vocabulary of implied readers and textual address; and reception studies, which typically gather data through empirical work with children. The figure of the “child reader” is claimed by both traditions, although in one case that reader is a textual construct and in the other a human being; yet this ambiguity is not typically addressed within studies of individual texts. Puella Magi Madoka Magica, a complex work that disrupts viewer expectations and genre assumptions, both destabilises its implied viewership and challenges conventional beliefs about the tastes and capacities of actual viewers, especially the extent to which those viewers can be categorised by age or gender. I argue that, by taking a sideways step from page to screen, and especially by analysing a non-Western work, it is possible to highlight the contingent and arbitrary nature of some of the assumptions that permeate literary critical discussion, and to help bring narratalogical and reception studies into a more productive relationship

Supporting parent-child conversations in a history museum

BACKGROUND: Museums can serve as rich resources for families to learn about the social world through engagement with exhibits and parent-child conversation about exhibits. AIMS: This study examined ways of engaging parents and child about two related exhibits at a cultural and history museum. Sample participants consisted of families visiting the Animal Antics and the Gone Potty exhibits at the British Museum. METHODS: Whilst visiting two exhibits at the British Museum, 30 families were assigned to use a backpack of activities, 13 were assigned to a booklet of activities, and 15 were assigned to visit the exhibits without props (control condition). RESULTS: Compared to the families in the control condition, the interventions increased the amount of time parents and children engaged together with the exhibit. Additionally, recordings of the conversations revealed that adults asked more questions related to the exhibits when assigned to the two intervention conditions compared to the control group. Children engaged in more historical talk when using the booklets than in the other two conditions. CONCLUSIONS: The findings suggest that providing support with either booklets or activities for children at exhibits may prove beneficial to parent-child conversations and engagement with museum exhibits

Diabetes in Canadian Women

Health Issue: Diabetes mellitus (DM) is a chronic health condition affecting 4.8 % of Canadian adults ≥ 20 years of age. The prevalence increases with age. According to the National Diabetes Surveillance System (NDSS) (1998–1999), approximately 12 % of Canadians aged 60–74 years are affected. One-third of cases may remain undiagnosed. The projected increase in DM prevalence largely results from rising rates of obesity and inactivity. Key Findings: DM in Canada appears to be more common among men than women. However, among Aboriginal Canadians, two-thirds of affected individuals are women. Although obesity is more prevalent among men than women (35 % vs. 27%), the DM risk associated with obesity is greater for women. Socio-economic status is inversely related to DM prevalence but the incomerelated disparities are greater among women. Polycystic ovarian syndrome affects 5–7 % of reproductive-aged women and doubles their risk for DM. Women with gestational diabetes frequently develop DM over the next 10 years. Data Gaps and Recommendations: Studies of at risk ethnic/racial groups and women with gestational diabetes are needed. Age and culturally sensitive programs need to be developed an

Numerical modelling of magma reservoir processes

For many years, volcanic and igneous processes were explained by the storage of magma in a melt-rich magma body, where chemical differentiation is controlled by fractional crystallisation. However, this idea for the storage and chemical differentiation of magma in the Earth’s crust has been challenged by data from natural magmatic systems. Evidence suggests that melt-rich magma bodies are most likely a transient feature, and it is now thought that magma storage occurs in a vertically extensive magmatic system, mainly comprising of high-crystallinity ‘mush’. Mush is defined as closely packed crystals which create a crystalline framework, where melt survives within the pore space. A recent numerical model showed how a high-crystallinity magma reservoir can form in response to the intrusion of parental magma. The reservoir mainly consists of mush, but forms low-crystallinity evolved magma at the top of the reservoir, with chemical differentiation being mainly controlled by reactive melt flow. In this thesis, the recent numerical model for the formation and storage of magma in the crust is extended to investigate observed behaviours of magmatic systems unexplained through the context of high-crystallinity magma reservoirs. These behaviours include: the eruption of large volumes of low-crystallinity magma, the formation and development of a vertically extensive magmatic system and the presence of multiple heat sources in the crust to create and grow the reservoir. Results from the extended model suggest the size, frequency, and composition of eruptions to be controlled by the buoyancy-driven evacuation of magma from a source magma reservoir. The numerical model also shows the magma to be stored as discrete mush bodies in a vertically extensive magmatic system, rather than a transcrustal mush; with the chemical diversity of the system being dependent on whether partial melting of the crust occurs. Furthermore, the presence of multiple heat sources in the model reduces the magma flux needed to form a magma reservoir and recreates long-lived magma storage observed in natural systems and not currently reproduced by numerical magmatic models.Open Acces