Spin precession and spin Hall effect in monolayer graphene/Pt nanostructures

Spin Hall effects have surged as promising phenomena for spin logics operations without ferromagnets. However, the magnitude of the detected electric signals at room temperature in metallic systems has been so far underwhelming. Here, we demonstrate a two-order of magnitude enhancement of the signal in monolayer graphene/Pt devices when compared to their fully metallic counterparts. The enhancement stems in part from efficient spin injection and the large resistivity of graphene but we also observe 100% spin absorption in Pt and find an unusually large effective spin Hall angle of up to 0.15. The large spin-to-charge conversion allows us to characterise spin precession in graphene under the presence of a magnetic field. Furthermore, by developing an analytical model based on the 1D diffusive spin-transport, we demonstrate that the effective spin-relaxation time in graphene can be accurately determined using the (inverse) spin Hall effect as a means of detection. This is a necessary step to gather full understanding of the consequences of spin absorption in spin Hall devices, which is known to suppress effective spin lifetimes in both metallic and graphene systems.Comment: 14 pages, 6 figures. Accepted in 2D Materials. https://doi.org/10.1088/2053-1583/aa882

Understanding the development of minimum unit pricing of alcohol in Scotland: A qualitative study of the policy process

Background: Minimum unit pricing of alcohol is a novel public health policy with the potential to improve population health and reduce health inequalities. Theories of the policy process may help to understand the development of policy innovation and in turn identify lessons for future public health research and practice. This study aims to explain minimum unit pricing’s development by taking a ‘multiple-lenses’ approach to understanding the policy process. In particular, we apply three perspectives of the policy process (Kingdon’s multiple streams, Punctuated-Equilibrium Theory, Multi-Level Governance) to understand how and why minimum unit pricing has developed in Scotland and describe implications for efforts to develop evidence-informed policymaking. Methods: Semi-structured interviews were conducted with policy actors (politicians, civil servants, academics, advocates, industry representatives) involved in the development of MUP (n = 36). Interviewees were asked about the policy process and the role of evidence in policy development. Data from two other sources (a review of policy documents and an analysis of evidence submission documents to the Scottish Parliament) were used for triangulation. Findings: The three perspectives provide complementary understandings of the policy process. Evidence has played an important role in presenting the policy issue of alcohol as a problem requiring action. Scotland-specific data and a change in the policy ‘image’ to a population-based problem contributed to making alcohol-related harms a priority for action. The limited powers of Scottish Government help explain the type of price intervention pursued while distinct aspects of the Scottish political climate favoured the pursuit of price-based interventions. Conclusions: Evidence has played a crucial but complex role in the development of an innovative policy. Utilising different political science theories helps explain different aspects of the policy process, with Multi-Level Governance particularly useful for highlighting important lessons for the future of public health policy

An exploratory review of HIV prevention mass media campaigns targeting men who have sex with men.

BACKGROUND: Men who have sex with men (MSM) are at increased risk of HIV infection in both high- and low-income settings. Mass media campaigns have been used as a means of communicating HIV health promotion messages to large audiences of MSM. There is no consensus on which designs are most appropriate to evaluate the process and outcomes of such interventions. METHODS: An exploratory review was conducted to assess research examining awareness, acceptability, effects on HIV testing, disclosure and sexual risk, and cost-effectiveness of HIV mass media campaigns targeting MSM. We searched for quantitative and qualitative studies published between 1990 and May 2011 via the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, Psych Info, ISI Web of Science, OpenGrey and COPAC, and contacting experts. No exclusions were made on the basis of study design or methods because our primary aim was to map evidence. We appraised study quality and present a narrative synthesis of findings. RESULTS: Sixteen reports from 12 studies were included. All were from high-income countries and most examined multi-media interventions. Half of the studies were single cross-sectional surveys. Three repeat cross-sectional studies collected data pre and post the campaign launch. The remaining three studies monitored routine data. Three studies included a nested qualitative component. Campaign coverage was the most commonly reported outcome (9 studies). Imagery, tone of language, content and relevance were identified in the qualitative research as factors influencing campaign acceptability. HIV testing rates (or intention to test) were reported by five studies. Two studies reported that testing rates were higher among men who had seen the campaigns compared to men who had not, but this may reflect confounding. Findings were less consistent regarding reductions in sexual risk behaviours (4 studies). None of the studies examined cost-effectiveness. CONCLUSIONS: Campaigns aim to provide MSM with information to help prevent transmission of HIV and to address increasing motivation and changing norms towards precautionary behaviours. However, the limitations of mass media in imparting skills in effecting behaviour change should be recognised, and campaigns supplemented by additional components may be better-suited to achieving these goals

Development of soil hydraulic properties below grassland, ancient forest and plantation forests

Woodlands in particular have the potential to alleviate flooding by delaying the downstream passage of flood flows, reducing the volume of runoff through interception (Calder et al. 2003) and promoting rainfall infiltration into the soil (Thomas & Nisbet, 2006). The natural processes which occur below ground to enable a change in hydraulic pathways and storage are complex and are dependent not only on geology, but also on landuse. We focus this study on below-ground changes that influence soil water characteristics, such as soil hydraulic conductivity, soil water retention and soil structure, which are all important in understanding how the planting of trees can mitigate localised flooding

Natural flood management: does age of forest influence flood mitigation?

Forestry has the potential to alleviate flooding by delaying the downstream passage of flood flows, reducing the volume of runoff through interception (Calder et al. 2003) and promoting rainfall infiltration into the soil (Forest Research, 2010). However, it is difficult to predict how much a forest needs to grow, before there is any significant effect on soil properties to increase the capacity to 1) store water, 2) increase soil infiltration, 3) slow water and reduce water flow connectivity to rivers. The structural coupling between plant roots and soil environment determines flow paths through the soil, where root growth and die-back influences soil hydraulic properties, increasing macropore distribution (Bengough, 2012) and soil permeability. We test the hypothesis: as the forest grows soil permeability below forests will increase, due to increasing macropore structure

The possibility of critical realist randomised controlled trials.

BACKGROUND: Some realists have criticised randomised controlled trials for their inability to explain the causal relations that they identify; to take into account the influence of the social context of the interventions they evaluate; and to account for individual difference. However, among realists, there is controversy over whether it is possible to improve trials by making them realist, or whether realism and the philosophical assumptions underlying trials are incompatible. This paper contributes to the debate in Trials on this issue. The debate thus far has concentrated on the possibility of combining trial methodology with that of realist evaluation. MAIN BODY: We concur with the contention that it is not feasible to combine randomised controlled trial design with the realist evaluation approach. However, we argue that a different variant of realism, critical realism, provides a more appropriate theoretical grounding for realist trials. In contrast to realist evaluation, which regards social mechanisms as an amalgam of social resources and people's reasoning, critical realism insists on their distinction. It does so on the basis of its assertion of the need to distinguish between social structures (in which resources lie) and human agency (which is at least partly guided by reasoning). From this perspective, conceiving of social mechanisms as external to participants can be seen as a valid methodological strategy for supplementing the exclusive concentration of trials on outcomes. While accepting realist evaluation's insistence that causality in open systems involves a configuration of multiple generative mechanisms, we adopt the critical realist interpretation of the experimental method, which sees it as creating artificial closure in order to identify the effects of specific causal mechanisms. If randomised controlled trials can be regarded as epidemiological proxies that substitute probabilistic controls over extraneous factors for closed experiments, their examination of the powers of discrete mechanisms through observation of the variation of outcomes is appropriate. CONCLUSION: While there are still issues to be resolved, critical realist randomised controlled trials are possible and have the potential to overcome some of the difficulties faced by traditional trial designs in accounting for the influence of social context and individual interpretation

How Do Contextual Factors Influence Implementation and Receipt of Positive Youth Development Programs Addressing Substance Use and Violence? A Qualitative Meta-Synthesis of Process Evaluations

Objective:Positive youth development (PYD) often aims to prevent tobacco, alcohol, and drugs use and violence. We systematically reviewed PYD interventions, synthesizing process, and outcomes evidence. Synthesis of outcomes, published elsewhere, found no overall evidence of reducing substance use or violence but notable variability of fidelity. Our synthesis of process evaluations examined how implementation varied and was influenced by context.Data Source:Process evaluations of PYD aiming to reduce substance use and violence.Study Inclusion Criteria:Overall review published since 1985; written in English; focused on youth aged 11 to 18 years; focused on interventions addressing multiple positive assets; reported on theory, process, or outcomes; and concerned with reducing substance use or violence. Synthesis of process evaluations examined how implementation varies with or is influenced by context.Data Extraction:Two reviewers in parallel.Data Synthesis:Thematic synthesis.Results:We identified 12 reports. Community engagement enhanced program appeal. Collaboration with other agencies could broaden the activities offered. Calm but authoritative staff increased acceptability. Staff continuity underpinned diverse activities and durable relationships. Empowering participants were sometimes in tension with requiring them to engage in diverse activities.Conclusion:Our systematic review identified factors that might help improve the fidelity and acceptability of PYD interventions. Addressing these might enable PYD to fulfill its potential as a means of promoting health

Strongly anisotropic spin relaxation in graphene/transition metal dichalcogenide heterostructures at room temperature

Graphene has emerged as the foremost material for future two-dimensional spintronics due to its tuneable electronic properties. In graphene, spin information can be transported over long distances and, in principle, be manipulated by using magnetic correlations or large spin-orbit coupling (SOC) induced by proximity effects. In particular, a dramatic SOC enhancement has been predicted when interfacing graphene with a semiconducting transition metal dechalcogenide, such as tungsten disulphide (WS$_2$). Signatures of such an enhancement have recently been reported but the nature of the spin relaxation in these systems remains unknown. Here, we unambiguously demonstrate anisotropic spin dynamics in bilayer heterostructures comprising graphene and WS$_2$. By using out-of-plane spin precession, we show that the spin lifetime is largest when the spins point out of the graphene plane. Moreover, we observe that the spin lifetime varies over one order of magnitude depending on the spin orientation, indicating that the strong spin-valley coupling in WS$_2$ is imprinted in the bilayer and felt by the propagating spins. These findings provide a rich platform to explore coupled spin-valley phenomena and offer novel spin manipulation strategies based on spin relaxation anisotropy in two-dimensional materials

The health benefits of secondary education in adolescents and young adults: An international analysis in 186 low-, middle- and high-income countries from 1990 to 2013.

BACKGROUND: The health benefits of secondary education have been little studied. We undertook country-level longitudinal analyses of the impact of lengthening secondary education on health outcomes amongst 15-24 year olds. METHODS: Exposures: average length of secondary and primary education from 1980 to 2013.Data/Outcomes: Country level adolescent fertility rate (AFR), HIV prevalence and mortality rate from 1989/90 to 2013 across 186 low-, middle- and high-income countries.Analysis: Longitudinal mixed effects models, entering secondary and primary education together, adjusted for time varying GDP and country income status. Longitudinal structural marginal models using inverse probability weighting (IPW) to take account of time varying confounding by primary education and GDP. Counterfactual scenarios of no change in secondary education since 1980/1990 were estimated from model coefficients for each outcome. FINDINGS: Each additional year of secondary education decreased AFR by 8.4% in mixed effects models and 14.6% in IPW models independent of primary education and GDP. Counterfactual analyses showed the proportion of the reduction in adolescent fertility rate over the study period independently attributable to secondary education was 28% in low income countries. Each additional year of secondary education reduced mortality by 16.9% for 15-19 year and 14.8% for 20-24 year old young women and 11.4% for 15-19 year and 8.8% for 20-24 year old young men. Counterfactual scenarios suggested 12% and 23% of the mortality reduction for 15-19 and 20-24 year old young men was attributable to secondary education in low income countries. Each additional year of secondary education was associated with a 24.5% and 43.1% reduction in HIV prevalence amongst young men and women. INTERPRETATION: The health benefits associated with secondary education were greater than those of primary education and were greatest amongst young women and those from low income countries. Secondary education has the potential to be a social vaccine across many outcomes in low and middle income countries

Men who have sex with men in Great Britain: comparing methods and estimates from probability and convenience sample surveys

OBJECTIVE: To examine sociodemographic and behavioural differences between men who have sex with men (MSM) participating in recent UK convenience surveys and a national probability sample survey. METHODS: We compared 148 MSM aged 18-64 years interviewed for Britain's third National Survey of Sexual Attitudes and Lifestyles (Natsal-3) undertaken in 2010-2012, with men in the same age range participating in contemporaneous convenience surveys of MSM: 15 500 British resident men in the European MSM Internet Survey (EMIS); 797 in the London Gay Men's Sexual Health Survey; and 1234 in Scotland's Gay Men's Sexual Health Survey. Analyses compared men reporting at least one male sexual partner (past year) on similarly worded questions and multivariable analyses accounted for sociodemographic differences between the surveys. RESULTS: MSM in convenience surveys were younger and better educated than MSM in Natsal-3, and a larger proportion identified as gay (85%-95% vs 62%). Partner numbers were higher and same-sex anal sex more common in convenience surveys. Unprotected anal intercourse was more commonly reported in EMIS. Compared with Natsal-3, MSM in convenience surveys were more likely to report gonorrhoea diagnoses and HIV testing (both past year). Differences between the samples were reduced when restricting analysis to gay-identifying MSM. CONCLUSIONS: National probability surveys better reflect the population of MSM but are limited by their smaller samples of MSM. Convenience surveys recruit larger samples of MSM but tend to over-represent MSM identifying as gay and reporting more sexual risk behaviours. Because both sampling strategies have strengths and weaknesses, methods are needed to triangulate data from probability and convenience surveys