Eclipses, bursts and outflows in highly inclined X-ray binaries

Accretion, the capture of nearby material by the strong gravitational pull of an object, is ubiquitous throughout the universe and is often observed around newly forming stars, planets or compact objects like neutron stars (NSs) and black holes (BHs). X-ray binaries are transient systems in which a NS or BH heats material accreted from a companion star and thus glows brightly in X-rays. These bright X-rays are easy to observe with existing X-ray telescopes. Therefore, X-ray binaries serve as unique laboratories for fundamental physics, allowing us to test different gravitational regimes, probe the state of the ultra-dense matter in the cores of NSs and determine the maximum possible NS mass. In this thesis, I pioneer the X-ray TRansit and EClipse model, x-trec to provide a novel and precise way of measuring NS masses, thus informing on the equation of state of ultra-dense matter and the classification of merging compact objects. My model exploits eclipsing X-ray binaries, in which the binary inclination, i, and mass ratio, q relate via the duration of totality, te, thus the degeneracy between i and q is disentangled through accurate mapping of the eclipse profile. I demonstrate the abilities of x-trec by applying it to archival observations of two eclipsing low-mass X-ray binaries, EXO 0748 – 676 and Swift J1858.6 – 0814, precisely determining the i and q for both systems. Furthermore, the novel consideration of the companion star’s outflow by x-trec allows it to diagnose the source of any absorbing material within the systems. For EXO 0748 – 676 and Swift J1858.6 – 0814, I use this modelling technique to diagnose an irradiation-driven ablated outflow in both systems, suggesting they are related to spider pulsars. I thoroughly explore this relation, infer that these two binaries are false widows, and predict that the ablated material in EXO 0748 – 676 leads to Type-I X-ray bursts being observable during the X-ray eclipses

Reversible Pebbling Game for Quantum Memory Management

Quantum memory management is becoming a pressing problem, especially given the recent research effort to develop new and more complex quantum algorithms. The only existing automatic method for quantum states clean-up relies on the availability of many extra resources. In this work, we propose an automatic tool for quantum memory management. We show how this problem exactly matches the reversible pebbling game. Based on that, we develop a SAT-based algorithm that returns a valid clean-up strategy, taking the limitations of the quantum hardware into account. The developed tool empowers the designer with the flexibility required to explore the trade-off between memory resources and number of operations. We present three show-cases to prove the validity of our approach. First, we apply the algorithm to straight-line programs, widely used in cryptographic applications. Second, we perform a comparison with the existing approach, showing an average improvement of 52.77%. Finally, we show the advantage of using the tool when synthesizing a quantum circuit on a constrained near-term quantum device.Comment: In Proc. Design Automation and Test in Europe (DATE 2019

Unleasing Z Monster

Houston Community College will share experiences of creating what sometimes feels like an enormous and unrealizable task and what may seem to be a monstrous educational disruption, a Z-Degree. Building a Z-Degree might seem like simply a matter of packaging courses, but in reality, it requires design, intention, and cultivation. After years of piecemeal attempts to adopt and promote OER, HCC gained focus with a directive to launch a Z-Degree, which came from multiple stakeholders, including students, Board of Trustees, senior administration, and faculty champions. This commitment enabled us to secure external and internal funding sources, clarify policies and procedures, and ultimately place OER on a solid foundation for the future. We will share our process for revising and adopting an OER policy guide, identifying and recruiting faculty, and engaging with multiple stakeholders within the institution (Board of Trustees, administration, faculty, libraries, CTLE, and students). HCC has partnered with Lumen Learning to provide initial training and course hosting, and we are working with our Institute for Instructional Engagement & Development to create a sustainable infrastructure to build our capacity of OER course offerings. In some cases, it has been necessary to make compromises to bring critical programs on board, but the college has done so out of a commitment to the ultimate goal of building a complete degree plan and developing OERs options for the future. Finally, HCC is establishing a program for data collection and analysis in order to understand the effects of the initiative on key indicators. This session will include real time polls and Twitter feeds. It is aimed at all levels, but particularly colleges who want to launch a Z Degree

Structural and dielectric studies of the phase behaviour of the topological ferroelectric La1-xNdxTaO4

We thank the University of St Andrews and EPSRC (via DTG studentships to CALD and JG) for funding,The layered perovskite LaTaO4 has been prepared in its polar orthorhombic polymorphic form at ambient temperature. Although no structural phase transition is observed in the temperature interval 25° C < T < 500 °C, a very large axial thermal contraction effect is seen, which can be ascribed to an anomalous buckling of the perovskite octahedral layer. The non-polar monoclinic polymorph can be stabilised at ambient temperature by Nd-doping. A composition La0.90Nd0.10TaO4 shows a first-order monoclinic-orthorhombic (non-polar to polar) transition in the region 250° C < T < 350 °C. Dielectric responses are observed at both the above structural events but, despite the ‘topological ferroelectric’ nature of orthorhombic LaTaO4, we have not succeeded in obtaining ferroelectric P–E hysteresis behaviour. Structural relationships in the wider family of AnBnX3n+2 layered perovskites are discussed.Publisher PDFPeer reviewe

The Influence of Moral Concerns on Memory for Individuals and their Actions

We explore how learning about individual behaviors that violate or uphold moral norms impacts our ability to recognize individuals who engage in them. We also explore how behaviors representing five moral foundations influence facial recognition differently according to whether the behavior relates to moral foundations that are typically emphasized by liberals (harm/fairness) or by conservatives (loyalty/authority/purity). We observed higher associative memory for individuals linked with behaviors that violated liberal principles than for individuals linked with behaviors that violated conservative principles. In addition, we examined the contribution of implicit processes in shaping early impressions and judgments of individuals

Hog Producers\u27 Risk Management Attitudes and Desire for Additional Risk Management Education

Hog producers in Indiana and Nebraska were surveyed about sources of risk, effectiveness of risk management strategies, and prior participation in and desire for additional risk management education. Ownership of hogs by the producer, size of the operation, and age did have significant effects on ratings of both sources of risk and effectiveness of risk management strategies. Probit analysis found age, prior attendance, knowledge and prior use of the tool, level of integration, and concern about price and performance risk have significant effects on interest in further education about production contracts, futures and options, packer marketing contracts, and financial management

How effective is ‘greening’ of urban areas in reducing human exposure to ground-level ozone concentrations, UV exposure and the ‘urban heat island effect’? An updated systematic review

Abstract Background This review updates a systematic review published in 2010 ( http://www.environmentalevidence.org/completed-reviews/how-effective-is-greening-of-urban-areas-in-reducing-human-exposure-to-ground-level-ozone-concentrations-uv-exposure-and-the-urban-heat-island-effect ) which addressed the question: How effective is ‘greening’ of urban areas in reducing human exposure to ground-level ozone concentrations, UV exposure and the ‘urban heat island effect’? Methods Searches of multiple databases and journals for relevant published articles and grey literature were conducted. Organisational websites were searched for unpublished articles. Eligibility criteria were applied at title, abstract and full text and included studies were critically appraised. Consistency checks of these processes were undertaken. Pre-defined data items were extracted from included studies. Quantitative synthesis was performed through meta-analysis and narrative synthesis was undertaken. Review findings 308 studies were included in this review. Studies were spread across all continents and climate zones except polar but were mainly concentrated in Europe and temperate regions. Most studies reported on the impact of urban greening on temperature with fewer studies reporting data on ground-level UV radiation, ozone concentrations (or precursors) or public health indicators. The findings of the original review were confirmed; urban green areas tended to be cooler than urban non-green areas. Air temperature under trees was on average 0.8 °C cooler but treed areas could be warmer at night. Cooling effect showed tree species variation. Tree canopy shading was a significant effect modifier associated with attenuation of solar radiation during the day. Urban forests were on average 1.6 °C cooler than comparator areas. Treed areas and parks and gardens were associated with improved human thermal comfort. Park or garden cooling effect was on average 0.8 °C and trees were a significant influence on this during the day. Park or garden cooling effect extended up to 1.25 kms beyond their boundaries. Grassy areas were cooler than non-green comparators, both during daytime and at night, by on average 0.6 °C. Green roofs and walls showed surface temperature cooling effect (2 and 1.8 °C on average respectively) which was influenced by substrate water content, plant density and cover. Ground-level concentrations of nitrogen oxides were on average lower by 1.0 standard deviation units in green areas, with tree species variation in removal of these pollutants and emission of biogenic volatile organic compounds (precursors of ozone). No clear impact of green areas on ground level ozone concentrations was identified. Conclusions Design of urban green areas may need to strike a balance between maximising tree canopy shading for day-time thermal comfort and enabling night-time cooling from open grassy areas. Choice of tree species needs to be guided by evapotranspiration potential, removal of nitrogen oxides and emission of biogenic volatile organic compounds. Choice of plant species and substrate composition for green roofs and walls needs to be tailored to local thermal comfort needs for optimal effect. Future research should, using robust study design, address identified evidence gaps and evaluate optimal design of urban green areas for specific circumstances, such as mitigating day or night-time urban heat island effect, availability of sustainable irrigation or optimal density and distribution of green areas. Future evidence synthesis should focus on optimal design of urban green areas for public health benefit