Layered controller synthesis for dynamic multi-agent systems

In this paper we present a layered approach for multi-agent control problem, decomposed into three stages, each building upon the results of the previous one. First, a high-level plan for a coarse abstraction of the system is computed, relying on parametric timed automata augmented with stopwatches as they allow to efficiently model simplified dynamics of such systems. In the second stage, the high-level plan, based on SMT-formulation, mainly handles the combinatorial aspects of the problem, provides a more dynamically accurate solution. These stages are collectively referred to as the SWA-SMT solver. They are correct by construction but lack a crucial feature: they cannot be executed in real time. To overcome this, we use SWA-SMT solutions as the initial training dataset for our last stage, which aims at obtaining a neural network control policy. We use reinforcement learning to train the policy, and show that the initial dataset is crucial for the overall success of the method

Parents' perception and experiences of national tests in primary school in Wales: An interpretative phenomenological analysis

Pupils in Wales currently take national tests in reading and numeracy every year from Year 2 until Year 9 (Welsh Government (WG), 2017a). Existing literature considering the experience of such external, standardised tests in primary schools in the United Kingdom (UK) has tended to focus on English children taking standard assessment tests (SATs) at the end of Year 2 and 6 only, specifically exploring the impact of ‘test anxiety’ and closely related constructs (e.g. Connor, 2001, 2003; Connors, Putwain, Woods & Nicholson, 2009; Putwain, Connors, Woods & Nicholson, 2012). Whilst there is a growing body of research considering the English primary assessment context, it is argued that there remains a paucity of research considering the unique Welsh context, and, furthermore, a lack of consideration for the parent voice in enabling a broader and more holistic view of the test experience. Therefore, this research aimed to provide an insight into parents’ perceptions and experiences of primary school children taking the national tests in Wales. Semi-structured interviews were conducted with eight parents recruited from two primary schools in different areas of Wales. Recordings of the interviews were transcribed verbatim, and interpretative phenomenological analysis (IPA) was completed. Three super-superordinate themes were identified: ‘relationships’, ‘constructions of child’s experience’ and ‘constructions of the test’. The research findings are discussed in relation to existing theoretical and research literature; namely concepts from Festinger’s (1957) cognitive dissonance theory, a joint family and school systems approach (Dowling & Osborne, 2003) and the relevance to bioecological systems theories of child development (Bronfenbrenner, 1979; Bronfenbrenner & Ceci, 1994). The implications of the current research for the practice of educational psychology are discussed, including how educational psychologists could work at a variety of systemic levels using tools to explore the test experience with children, parents and school staff, are discussed, alongside the strengths and limitations of the current study. Further areas for future research are suggested, such as explicitly using a case study approach to explore a variety of different perspectives within one school context, as well as examining the hypothesis that cognitive dissonance exists throughout the system

Static Degradation of Electrospun Polycaprolactone Scaffolds

Static Degradation of Electrospun Polycaprolactone Scaffolds Emily Clement, Depts. of Biomedical Engineering and Electrical Engineering, Connor Donlan, Sam Cole, Sarah K. Saunders, and Johana Bracamonte, with Dr. Joao Soares, Dept. of Mechanical Engineering Introduction: Engineered tissue vascular grafts (ETVGs), composed of cells seeded on a biodegradable scaffold, can be used to replace non-functional blood vessels. The scaffold acts as a replacement for the extracellular matrix, providing structural support to the developing tissue. A common biodegradable scaffold material is polycaprolactone (PCL). The main degradation mechanism of PCL is hydrolysis, which can be catalyzed by the use of NaOH solutions. Acceleration techniques must be employed to obtain information about the degradation in shorter observation times. In this study, we will compare the effect of degradation on physical and mechanical properties from samples degraded in PBS solutions (that mimics the pH of biological environments), and alkaline NaOH solutions. We hypothesize that the accelerated degradation profiles can be correlated to degradation profiles under in vivo like conditions. Methods: This study focuses on PCL (PCL 80,000 g/mol) 3mm electrospun scaffolds. Accelerated conditions were produced by submerging the scaffolds in increased NaOH solutions. The weight loss, elastic modulus, and microstructure of the scaffolds were assessed after vacuum drying at 0, 7, 14, 21, and 42 days. Phosphate-buffered saline (PBS) solution was used to replicate physiological-like pH conditions. This group was tested for elastic modulus, weight loss, and thickness at 0, 3, and 6 months. Results: The rate of change in mass, fiber orientation, and mechanical stiffness increased as the alkalinity of the liquid media increased to pH 12.45. Changes in the mechanical properties of the scaffolds became noticeable after 3 weeks of degradation. A decrease in mass stiffness was observed following a steep decrease in mass. At 6 weeks of degradation, the samples experienced a 20% decrease from the original mass and a 50% drop in membrane stiffness. The scaffolds swelled shortly after degradation began, but the swelling decreased as the mass decreased. In the non-accelerated degradation group, the scaffolds exhibited an average mass loss of 10 +/- 7% with no significant changes to mechanical properties. The scaffold thickness swelled to 40 +/- 20%, aligning with our previous works that showed scaffold swelling decreases at a larger pH. Conclusions: If the degradation of PCL scaffolds in physiological pH conditions follows the same trend as those in accelerated conditions, a stage of pronounced decrease in mass will be accompanied by a significant decrease in membrane stiffness and porosity. We hypothesize that the accelerated and non-accelerated degradation profiles are equivalent, meaning accelerated degradation can be used as a base to predict a scaffold’s behavior in physiological conditions.https://scholarscompass.vcu.edu/uresposters/1358/thumbnail.jp

Climate Action In Megacities 3.0

"Climate Action in Megacities 3.0" (CAM 3.0) presents major new insights into the current status, latest trends and future potential for climate action at the city level. Documenting the volume of action being taken by cities, CAM 3.0 marks a new chapter in the C40-Arup research partnership, supported by the City Leadership Initiative at University College London. It provides compelling evidence about cities' commitment to tackling climate change and their critical role in the fight to achieve global emissions reductions

Science for Humanitarian Emergencies and Resilience (SHEAR) scoping study: Annex 3 - Early warning system and risk assessment case studies

This report provides case studies of Early Warning Systems (EWSs) and risk assessments encompassing three main hazard types: drought; flood and cyclone. The case studies are taken from ten countries across three continents (focusing on Africa, South Asia and the Caribbean). The case studies have been developed to assist the UK Department for International Development (DFID) to prioritise areas for Early Warning System (EWS) related research under their ‘Science for Humanitarian Emergencies and Resilience’ (SHEAR) programme. The aim of these case studies is to ensure that DFID SHEAR research is informed by the views of Non-Governmental Organisations (NGOs) and communities engaged with Early Warning Systems and risk assessments (including community-based Early Warning Systems). The case studies highlight a number of challenges facing Early Warning Systems (EWSs). These challenges relate to financing; integration; responsibilities; community interpretation; politics; dissemination; accuracy; capacity and focus. The case studies summarise a number of priority areas for EWS related research: • Priority 1: Contextualising and localising early warning information • Priority 2: Climate proofing current EWSs • Priority 3: How best to sustain effective EWSs between hazard events? • Priority 4: Optimising the dissemination of risk and warning information • Priority 5: Governance and financing of EWSs • Priority 6: How to support EWSs under challenging circumstances • Priority 7: Improving EWSs through monitoring and evaluating the impact and effectiveness of those system

Prevalence of reproductive tract infections and the predictive value of girls’ symptom-based reporting: findings from a cross-sectional survey in rural western Kenya

Objectives Reproductive tract infections (RTIs), including sexually acquired, among adolescent girls is a public health concern, but few studies have measured prevalence in low-middle-income countries. The objective of this study was to examine prevalence in rural schoolgirls in Kenya against their reported symptoms. Methods In 2013, a survey was conducted in 542 adolescent schoolgirls aged 14–17 years who were enrolled in a menstrual feasibility study. Vaginal self-swabbing was conducted after girls were interviewed face-to-face by trained nurses on symptoms. The prevalence of girls with symptoms and laboratory-confirmed infections, and the sensitivity, specificity, positive and negative predictive values of symptoms compared with laboratory results, were calculated. Results Of 515 girls agreeing to self-swab, 510 answered symptom questions. A quarter (24%) reported one or more symptoms; most commonly vaginal discharge (11%), pain (9%) or itching (4%). Laboratory tests confirmed 28% of girls had one or more RTI. Prevalence rose with age; among girls aged 16–17 years, 33% had infections. Bacterial vaginosis was the most common (18%), followed by Candida albicans (9%), Chlamydia trachomatis (3%), Trichomonas vaginalis (3%) and Neisseria gonorrhoeae (1%). Reported symptoms had a low sensitivity and positive predictive value. Three-quarters of girls with bacterial vaginosis and C. albicans, and 50% with T. vaginalis were asymptomatic. Conclusions There is a high prevalence of adolescent schoolgirls with RTI in rural Kenya. Public efforts are required to identify and treat infections among girls to reduce longer-term sequelae but poor reliability of symptom reporting minimises utility of symptom-based diagnosis in this population. Trial registration number: ISRCTN17486946