Observations of Intrahour Variable Quasars: Scattering in our Galactic Neighbourhood

Interstellar scintillation (ISS) has been established as the cause of the random variations seen at centimetre wavelengths in many compact radio sources on timescales of a day or less. Observations of ISS can be used to probe structure both in the ionized insterstellar medium of the Galaxy, and in the extragalactic sources themselves, down to microarcsecond scales. A few quasars have been found to show large amplitude scintillations on unusually rapid, intrahour timescales. This has been shown to be due to weak scattering in very local Galactic ``screens'', within a few tens of parsec of the Sun. The short variability timescales allow detailed study of the scintillation properties in relatively short observing periods with compact interferometric arrays. The three best-studied ``intrahour variable'' quasars, PKS 0405-385, J1819+3845 and PKS 1257-326, have been instrumental in establishing ISS as the principal cause of intraday variability at centimetre wavelengths. Here we review the relevant results from observations of these three sources.Comment: 10 pages, 4 figures, to appear in Astronomical and Astrophysical Transaction

Rapid interstellar scintillation of PKS B1257-326: two-station pattern time delays and constraints on scattering and microarcsecond source structure

We report measurements of time delays of up to 8 minutes in the centimeter wavelength variability patterns of the intra-hour scintillating quasar PKS 1257-326 as observed between the VLA and the ATCA on three separate epochs. These time delays confirm interstellar scintillation as the mechanism responsible for the rapid variability, at the same time effectively ruling out the coexistence of intrinsic intra-hour variability in this source. The time delays are combined with measurements of the annual variation in variability timescale exhibited by this source to determine the characteristic length scale and anisotropy of the quasar's intensity scintillation pattern, as well as attempting to fit for the bulk velocity of the scattering plasma responsible for the scintillation. We find evidence for anisotropic scattering and highly elongated scintillation patterns at both 4.9 and 8.5 GHz, with an axial ratio > 10:1, extended in a northwest direction on the sky. The characteristic scale of the scintillation pattern along its minor axis is well determined, but the high anisotropy leads to degenerate solutions for the scintillation velocity. The decorrelation of the pattern over the baseline gives an estimate of the major axis length scale of the scintillation pattern. We derive an upper limit on the distance to the scattering plasma of no more than 10 pc.Comment: 27 pages, 6 figures, accepted for publication in Ap

What accounts for ‘England’s green and pleasant land’? A panel data analysis of mental health and land cover types in rural England

This is the author’s version of a work that was accepted for publication in Landscape and Urban Planning. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published at doi:10.1016/j.landurbplan.2015.05.008.Exposure to green space is associated with a variety of positive health states. Research to date has focused primarily on ‘generic’ green space in urban areas, where green space is relatively scarce and where it is dominated by playing fields and parks. The current research adds to our understanding with an examination of relationships between different types of green space and mental health in rural areas in England (approximate rural population = 4 million). The aggregate land cover classes of Land Cover Map 2007 were linked to rural residential areas (Lower-level Super Output Areas) and then linked to rural participants (n = 2020) in the 18-year longitudinal British Household Panel Survey. Random effects regression of mental health (as measured by GHQ12 scores) against land cover enabled effects to be simultaneously estimated from both mean between-individual differences and from within-individual differences over time. The nine natural land cover classes (Broadleaved woodland; Coniferous woodland; Arable; Improved grassland; Semi-natural grassland; Mountain, heath and bog; Saltwater; Freshwater; Coastal) were not significantly associated with differences in mental health between individuals. However, significant relationships were observed between some types of land cover and within-individual change in mental health amongst individuals who relocated during the 18 annual waves of the panel. These findings indicate the presence of important health related ecosystem services from different land cover types that have not previously been investigated and which help more effective spatial planning and land use management.Economic and Social Research CouncilNational Institute for Health Research Health Protection Research Unit (NIHR HPRU

A seasonal cycle and an abrupt change in the variability characteristics of the intraday variable source S4 0954+65

The BLLac object S4 0954+65 is one of the main targets of the Urumqi monitoring program targeting IntraDay Variable (IDV) sources. Between August 2005 and December 2009, the source was included in 41 observing sessions, carried out at a frequency of 4.8 GHz. The time analysis of the collected light curves, performed by applying both a structure function analysis and a specifically developed wavelet-based algorithm, discovered an annual cycle in the variability timescales, suggesting that there is a fundamental contribution by interstellar scintillation to the IDV pattern of the source. The combined use of the two analysis methods also revealed that there was a dramatic change in the variability characteristics of the source between February and March 2008, at the starting time of a strong outburst phase. The analysis' results suggest that the flaring state of the source coincides with the appearance of multiple timescales in its light curves, indicating that changes in the structure of the relativistically moving emitting region may strongly influence the variability observed on IDV timescales.Comment: 9 pages, 8 figures and 3 tables. Accepted for publication in Astronomy and Astrophysic

Beyond greenspace: an ecological study of population general health and indicators of natural environment type and quality.

This is a freely-available open access publication. Please cite the published version which is available via the DOI link in this record.BACKGROUND: Many studies suggest that exposure to natural environments ('greenspace') enhances human health and wellbeing. Benefits potentially arise via several mechanisms including stress reduction, opportunity and motivation for physical activity, and reduced air pollution exposure. However, the evidence is mixed and sometimes inconclusive. One explanation may be that "greenspace" is typically treated as a homogenous environment type. However, recent research has revealed that different types and qualities of natural environments may influence health and wellbeing to different extents. METHODS: This ecological study explores this issue further using data on land cover type, bird species richness, water quality and protected or designated status to create small-area environmental indicators across Great Britain. Associations between these indicators and age/sex standardised prevalence of both good and bad health from the 2011 Census were assessed using linear regression models. Models were adjusted for indicators of socio-economic deprivation and rurality, and also investigated effect modification by these contextual characteristics. RESULTS: Positive associations were observed between good health prevalence and the density of the greenspace types, "broadleaf woodland", "arable and horticulture", "improved grassland", "saltwater" and "coastal", after adjusting for potential confounders. Inverse associations with bad health prevalence were observed for the same greenspace types, with the exception of "saltwater". Land cover diversity and density of protected/designated areas were also associated with good and bad health in the predicted manner. Bird species richness (an indicator of local biodiversity) was only associated with good health prevalence. Surface water quality, an indicator of general local environmental condition, was associated with good and bad health prevalence contrary to the manner expected, with poorer water quality associated with better population health. Effect modification by income deprivation and urban/rural status was observed for several of the indicators. CONCLUSIONS: The findings indicate that the type, quality and context of 'greenspace' should be considered in the assessment of relationships between greenspace and human health and wellbeing. Opportunities exist to further integrate approaches from ecosystem services and public health perspectives to maximise opportunities to inform policies for health and environmental improvement and protection.Economic and Social Research CouncilEuropean Regional Development Fund Programme 2007 to 2013 and European Social Fund Convergence Programme for Cornwall and the Isles of Scill

Evaluating the acceptability of a co-produced and co-delivered mental health public engagement festival: Mental Health Matters, Jakarta, Indonesia

Background: Public engagement events are an important early strategy in developing a meaningful research agenda, which is more impactful and beneficial to the population. Evidence indicates the potential of such activities to promote mental health literacy. However, this has not yet been explored in Indonesia. Aim: This paper describes a mental health public engagement festival carried out in Indonesia in November 2018 and uses evaluation data to consider the acceptability and use of such activities in Indonesia in the future. Method: Evaluation data was collected from 324 of the 737 people who attended a six-day mental health festival comprising 18 events including public lectures, film screenings, arts activities, exercise classes and panel discussions. Attendees were asked to evaluate the festival in terms of its quality, benefits and areas for improvement. Descriptive statistics were used to analyse the evaluation data. 87 service users, carers, academics and professionals also engaged in a research prioritisation exercise to collaboratively determine mental health research priorities for Indonesia. Results: Participants evaluated the festival extremely positively with a significant majority (92%) rating the quality of the festival as good or excellent. Attendees reported an increase in their understanding of mental health issues and identified intended behaviour change including an increased propensity for future engagement with mental health research. Key strengths of the festival included the central role of patients, carers and the local community in the design and delivery of the festival which promoted emotional engagement and development of shared understanding and the use of international experts which in attendees’ opinion further enhanced the credibility of festival activities. Conclusion: This manuscript indicates that a co-produced mental health public engagement festival is a potentially acceptable way to increase awareness of mental health in Indonesian populations. Future festivals should be larger in scope and target men, older people and the general public to maximise benefit and incorporate rigorous evaluation of effectiveness