Turbulence and wind velocity profiles from adaptive optics telemetry: a general and scalable solution for extremely large telescopes

Advanced Adaptive Optics (AO) instruments on ground-based telescopes require accurate knowledge of the strength and velocity of atmospheric turbulence. Measuring these parameters as a function of altitude assists point spread function reconstruction, AO temporal control techniques, smart scheduling of science cases and is required by wide-field AO systems to optimise the reconstruction of an observed wavefront. The variability of the atmosphere makes it important to have a measure of the turbulence profile in real-time. This measurement can be performed by iteratively fitting an analytically generated covariance matrix to the cross-covariance of Shack–Hartmann Wavefront Sensor (SHWFS) centroids. In this study we explore the benefits of reducing the number of cross-covariance data points and fitting to a covariance map Region of Interest (ROI). Both of these methods are based on the SLOpe Detection And Ranging (SLODAR) technique. A technique for using the covariance map ROI to measure and compensate for SHWFS misalignments is also introduced. We compare the accuracy of covariance matrix and map ROI optical turbulence profiling using simulated data from CANARY, an AO demonstrator on the 4.2 m William Herschel Telescope (WHT), La Palma. It is shown that the covariance map ROI optimises the accuracy of turbulence profiling. In addition, we show that the covariance map ROI reduces the fitting time for an Extremely Large Telescope-scale (ELT-scale) system by a factor of 72. SLODAR spatio-temporal analysis can be used to visualise the wind velocity profile. However, the limited altitude-resolution of current AO systems makes it difficult to disentangle the movement of independent layers. We address this issue and introduce a novel technique that uses SLODAR data analysis for automated wind velocity profiling. Simulated data from CANARY is used to demonstrate the proficiency of the technique. We apply our turbulence and wind velocity profiling techniques on-sky using data from both CANARY and the Adaptive Optics Facility (AOF). The AOF is on the 8.2m Yepun telescope at the Very Large Telescope (VLT), Paranal. On-sky turbulence and wind velocity profiles from CANARY are compared to contemporaneous profiles from Stereo-SCIDAR, a dedicated high-resolution atmospheric profiler. Wind velocity profiles from CANARY and the AOF are compared to the European Centre for Medium-range Weather Forecasts (ECMWF). We also present AOF time sequences that show detailed examples of turbulence and wind velocity profiles at the VLT. The software packages that we developed to collect all of the presented results are open-source. They can be configured to any tomographic AO system

Owning Peace: Assessing the Impact of Local Ownership of Police Reforms on Post-conflict Peace

In the aftermath of armed conflict the (re) establishment of well-functioning and legitimate security institutions is touted as fundamental for the development of sustainable peace. Post-conflict police reform, often carried out with considerable involvement from external donor organisations, has become one of the most frequently implemented mechanisms of peacebuilding. Unfortunately, the track record of post-conflict police reform is, so far, mixed at best. Scholars (see, Donais, 2008; Gordon, 2015) argue that donors too often fail to engage local actors during the reform process and ‘impose’ reforms that are neither wanted by the host state and its society, nor befitting of the context. As a result, reform processes fail due to a lack of what is referred to as ‘local ownership’. The overall aim of this study is to provide new empirical and theoretical insights into the effects of local ownership on post-conflict peacebuilding. The overarching research question this study aims to address is: How does the local ownership of post-conflict police reform impact post-conflict peace? To answer this question, this study takes a mixed methods approach. The first part of the analysis is statistical, and considers the effects of local ownership on police reform in every post-conflict country globally, from 1989-2014. It includes new global data on police reform, external involvement and four types of local ownership based on the engagement of local actors – the executive, parliament, the police and civil society – in post-conflict police reform. New global data on community policing and female representation programs is also presented. The second part of the analysis is qualitative, and was completed through fieldwork in Kosovo, where 23 people were interviewed in relation to local ownership and its effects on the post-conflict police reform process there. The participants were from external donor organisations, Kosovo Police and government personnel, and members of civil society. The findings of the quantitative study suggest that local ownership plays a vital role in the promotion of post-conflict peace. The strongest association to post-conflict peace pertains to executive ownership, while police and civil society ownership are also demonstrated to have a positive relationship to post conflict peace. The findings from the qualitative study support the quantitative analysis and show that local ownership was significant for the success of Kosovo’s police reform program and for its overall stability, highlighting the importance of executive and civil society ownership in particular. The results also showcase the importance of time, and that local ownership can be separated into ownership of the reform process, and ownership of the reformed institutions. The fieldwork also suggests three factors that have hindered the development of local ownership: corruption, justice and impunity issues, and socio-economic development. This is the first study to examine the effects of local ownership on any type of post-conflict peacebuilding using large-N global data. It contributes to existing research most notably in relation to the presentation of new global data on post-conflict police reform and local ownership. This study also reconceptualises the term local ownership and focuses on one aspect of it: the engagement between local and external actors. It also distinguishes between the breadth and the depth of engagement, and concerns itself with only the breadth of local actor engagement in reform processes. Through deepening our understanding of local ownership, the findings of this research shed light on how to improve the implementation of post-conflict police reform processes so that they are better able to meaningfully improve peace in post-conflict societies

SCUBA - A submillimetre camera operating on the James Clerk Maxwell Telescope

The Submillimetre Common-User Bolometer Array (SCUBA) is one of a new generation of cameras designed to operate in the submillimetre waveband. The instrument has a wide wavelength range covering all the atmospheric transmission windows between 300 and 2000 microns. In the heart of the instrument are two arrays of bolometers optimised for the short (350/450 microns) and long (750/850 microns) wavelength ends of the submillimetre spectrum. The two arrays can be used simultaneously, giving a unique dual-wavelength capability, and have a 2.3 arc-minute field of view on the sky. Background-limited performance is achieved by cooling the arrays to below 100 mK. SCUBA has now been in active service for over a year, and has already made substantial breakthroughs in many areas of astronomy. In this paper we present an overview of the performance of SCUBA during the commissioning phase on the James Clerk Maxwell Telescope (JCMT).Comment: 14 pages, 13 figures (1 JPEG), Proc SPIE vol 335

Keeping Unwanted Gulls Away - A Progress Report

Nearly 50 years ago, wires were strung over fish ponds to discourage fish-eating birds from taking fish destined for other uses (McAtee and Piper 1936). Twenty years ago, overwiring of open ditches began on airports to keep ducks from using them and causing hazards to aircraft (Solman 1973). Both techniques used coarse wires spaced closely enough to form a physical barrier to prevent ducks and herons from landing on or taking off from the water

Fresh Cement as a Frictional Non-Brownian Suspension

Cement is an essential construction material due to its ability to flow before later setting, however the rheological properties must be tightly controlled. Despite this, much understanding remains empirical. Using a combination of continuous and oscillatory shear flow, we compare fresh Portland cement suspensions to previous measurements on model non-Brownian suspensions to gain a micro-physical understanding. Comparing steady and small-amplitude oscillatory shear, we reveal two distinct jamming concentrations, and rcp, where the respective yield stresses diverge. As in model suspensions, the steady-shear jamming point is notably below the oscillatory jamming point, < rcp, suggesting that it is tied to frictional particle contacts. These results indicate that recently established models for the rheology of frictional, adhesive non-Brownian suspensions can be applied to fresh cement pastes, offering a new framework to understand the role of additives and fillers. Such micro-physical understanding can guide formulation changes to improve performance and reduce environmental impact

Topological organization of whole-brain white matter in HIV infection

Infection with human immunodeficiency virus (HIV) is associated with neuroimaging alterations. However, little is known about the topological organization of whole-brain networks and the corresponding association with cognition. As such, we examined structural whole-brain white matter connectivity patterns and cognitive performance in 29 HIV+ young adults (mean age = 25.9) with limited or no HIV treatment history. HIV+ participants and demographically similar HIV− controls (n = 16) residing in South Africa underwent magnetic resonance imaging (MRI) and neuropsychological testing. Structural network models were constructed using diffusion MRI-based multifiber tractography and T(1)-weighted MRI-based regional gray matter segmentation. Global network measures included whole-brain structural integration, connection strength, and structural segregation. Cognition was measured using a neuropsychological global deficit score (GDS) as well as individual cognitive domains. Results revealed that HIV+ participants exhibited significant disruptions to whole-brain networks, characterized by weaker structural integration (characteristic path length and efficiency), connection strength, and structural segregation (clustering coefficient) than HIV− controls (p < 0.05). GDSs and performance on learning/recall tasks were negatively correlated with the clustering coefficient (p < 0.05) in HIV+ participants. Results from this study indicate disruption to brain network integrity in treatment-limited HIV+ young adults with corresponding abnormalities in cognitive performance

Capturing cropland and grassland management impacts on soil carbon in the UK LULUCF inventory

This project aimed to identify the extent to which emissions due to changes in Soil Organic Carbon (SOC) stocks arising from Cropland and Grassland/Grazing Land management can be incorporated into the UK’s Land Use, Land Use Change and Forestry (LULUCF) inventory. Key management activities were identified which might affect SOC stocks. A literature review carried out as part of the project concluded that tillage reduction cannot be considered a reliable management option to increase the SOC content of UK soils. However increasing crop residue returns and increasing inputs of manure and fertiliser could increase SOC stock although the SOC stock increases resulting from manure and fertiliser inputs could be outweighed by increases nitrous oxide emissions and the risk of nitrate run-off. The review found that increasing crop yields through increased fertilisation and improved crop rotation could increase the annual input of crop residues and root exudate to soils and hence increase SOC on low fertility soils. Manure additions resulted in greater C sequestration than the addition of equivalent amounts of N as mineral fertiliser and the effect lasted longer. However, increasing inputs of nitrogen from fertiliser or manure risk increasing N2O emissions which could negate any increases in SOC stock. IPCC default stock change factors were judged to be inappropriate to the UK, based on expert opinion and the literature review findings. Therefore the project used the Daily DayCent and Landscape DNDC models to attempt to estimate stock change factors for Cropland management activities under UK conditions. Although based on a very limited dataset this suggested that the effect of Cropland management activities under UK conditions might be less than implied by the IPCC stock change factors. Tillage reduction was found to have little effect on SOC stocks. Increasing manure and crop residue inputs increased SOC stocks, with manure inputs being particularly effective. A framework for reporting SOC stock changes resulting from Cropland management was developed, and used to assess mitigation options. Overall the impact of Cropland Management on SOC is likely to be very small compared to other activities in the LULUCF inventory such as land use change. The most effective mitigation option was using Cropland from annual tillage crops to perennial crops, fallow and set aside. However given the need for food production there is limited scope for such change. Increasing manure, fertiliser and crop residue inputs gave smaller increases in SOC stocks, but practical considerations limit the scope of these actions. Lack of field data on the effect of Grassland improvement on SOC stocks was identified as a knowledge gap. The literature review suggested that intensification could increase SOC stocks under pasture on mineral soils. However, expert opinion suggested that this might not be the case for rough grazing on organo-mineral soils, where intensification might lead to SOC loss. This lack of data meant that it was not possible to calibrate or validate models to estimate UK specific stock change factors for Grassland. As the IPCC stock change factors were judged to be inappropriate to UK conditions assessment of the mitigation potential of Grassland management using these factors was not carried out to avoid presenting potentially misleading results. Suggested strategies for filling these knowledge gaps are outlined in the report. Attempts to assess grass/crop rotation patterns across the UK using data from the Integrated Administration and Control System (IACS) used to handle Common Agricultural Policy (CAP) payments were hampered by difficulties in obtaining access to the data. However land use change matrices were generated for England and Wales, and used to map areas of change. Subject to data availability, this approach could be used in future inventories to give a better representation the effect of rotation patterns on SOC stocks

The Attitudes to Ageing Questionnaire:Mokken Scaling Analysis

BACKGROUND:Hierarchical scales are useful in understanding the structure of underlying latent traits in many questionnaires. The Attitudes to Ageing Questionnaire (AAQ) explored the attitudes to ageing of older people themselves, and originally described three distinct subscales: (1) Psychosocial Loss (2) Physical Change and (3) Psychological Growth. This study aimed to use Mokken analysis, a method of Item Response Theory, to test for hierarchies within the AAQ and to explore how these relate to underlying latent traits. METHODS:Participants in a longitudinal cohort study, the Lothian Birth Cohort 1936, completed a cross-sectional postal survey. Data from 802 participants were analysed using Mokken Scaling analysis. These results were compared with factor analysis using exploratory structural equation modelling. RESULTS:Participants were 51.6% male, mean age 74.0 years (SD 0.28). Three scales were identified from 18 of the 24 items: two weak Mokken scales and one moderate Mokken scale. (1) 'Vitality' contained a combination of items from all three previously determined factors of the AAQ, with a hierarchy from physical to psychosocial; (2) 'Legacy' contained items exclusively from the Psychological Growth scale, with a hierarchy from individual contributions to passing things on; (3) 'Exclusion' contained items from the Psychosocial Loss scale, with a hierarchy from general to specific instances. All of the scales were reliable and statistically significant with 'Legacy' showing invariant item ordering. The scales correlate as expected with personality, anxiety and depression. Exploratory SEM mostly confirmed the original factor structure. CONCLUSIONS:The concurrent use of factor analysis and Mokken scaling provides additional information about the AAQ. The previously-described factor structure is mostly confirmed. Mokken scaling identifies a new factor relating to vitality, and a hierarchy of responses within three separate scales, referring to vitality, legacy and exclusion. This shows what older people themselves consider important regarding their own ageing

The effects of extensive grazing on the vegetation of a landscape-scale restoration site

The Wicken Fen Vision (Cambridgeshire, UK) is a landscape-scale habitat restoration project that uses process-driven, open-ended approaches to develop habitats on highly degraded and drained peat soils of former intensive arable land. The project land is extensively grazed with herds of free-roaming, minimally managed herds of Highland cattle and Konik horses. In one 119 ha area, seven 25m x 25 m grazing exclosures were erected and vascular plant species were recorded from 2007 to 2017. Plant species data were analysed to (1) compare changes in plant species composition and diversity in grazed and ungrazed areas; (2) use plant species traits and plant-environment associations to explore the nature of changes in plant composition; (3) use remote sensing to explore changes in vegetation structure; (4) examine the influence of land use histories on grazing outcomes in different parts of the site. There was a clear divergence through time between grazed and ungrazed areas, attributed to significantly greater canopy height, Ellenberg L (Light) and Ellenberg N (fertility) values within the exclosures. Species richness was significantly higher in grazed compared with ungrazed areas and species assemblages separated through the study period. After ten years, extensive free-roaming grazing has had significant impacts on vegetation structure and species richness but effects varied across the study site because of differing historical land use