Triangulating the Square and Squaring the Triangle: Quadtrees and Delaunay Triangulations are Equivalent

We show that Delaunay triangulations and compressed quadtrees are equivalent structures. More precisely, we give two algorithms: the first computes a compressed quadtree for a planar point set, given the Delaunay triangulation; the second finds the Delaunay triangulation, given a compressed quadtree. Both algorithms run in deterministic linear time on a pointer machine. Our work builds on and extends previous results by Krznaric and Levcopolous and Buchin and Mulzer. Our main tool for the second algorithm is the well-separated pair decomposition(WSPD), a structure that has been used previously to find Euclidean minimum spanning trees in higher dimensions (Eppstein). We show that knowing the WSPD (and a quadtree) suffices to compute a planar Euclidean minimum spanning tree (EMST) in linear time. With the EMST at hand, we can find the Delaunay triangulation in linear time. As a corollary, we obtain deterministic versions of many previous algorithms related to Delaunay triangulations, such as splitting planar Delaunay triangulations, preprocessing imprecise points for faster Delaunay computation, and transdichotomous Delaunay triangulations.Comment: 37 pages, 13 figures, full version of a paper that appeared in SODA 201

Identifying features associated with higher-quality hospital care and shorter length of admission for people with dementia : a mixed-methods study

Background: Concerns have repeatedly been expressed about the quality of inpatient care that people with dementia receive. Policies and practices have been introduced that aim to improve this, but their impact is unclear. Aims: To identify which aspects of the organisation and delivery of acute inpatient services for people with dementia are associated with higher-quality care and shorter length of stay. Design: Mixed-methods study combining a secondary analysis of data from the third National Audit of Dementia (2016/17) and a nested qualitative exploration of the context, mechanism and outcomes of acute care for people with dementia. Setting: Quantitative data from 200 general hospitals in England and Wales and qualitative data from six general hospitals in England that were purposively selected based on their performance in the audit. Participants: Quantitative data from clinical records of 10,106 people with dementia who had an admission to hospital lasting ≥ 72 hours and 4688 carers who took part in a cross-sectional survey of carer experience. Qualitative data from interviews with 56 hospital staff and seven carers of people with dementia. Main outcome measures: Length of stay, quality of assessment and carer-rated experience. Results: People with dementia spent less time in hospital when discharge planning was initiated within 24 hours of admission. This is a challenging task when patients have complex needs, and requires named staff to take responsibility for co-ordinating the discharge and effective systems for escalating concerns when obstacles arise. When trust boards review delayed discharges, they can identify recurring problems and work with local stakeholders to try to resolve them. Carers of people with dementia play an important role in helping to ensure that hospital staff are aware of patient needs. When carers are present on the ward, they can reassure patients and help make sure that they eat and drink well, and adhere to treatment and care plans. Clear communication between staff and family carers can help ensure that they have realistic expectations about what the hospital staff can and cannot provide. Dementia-specific training can promote the delivery of person-centred care when it is made available to a wide range of staff and accompanied by ‘hands-on’ support from senior staff. Limitations: The quantitative component of this research relied on audit data of variable quality. We relied on carers of people with dementia to explore aspects of service quality, rather than directly interviewing people with dementia. Conclusions: If effective support is provided by senior managers, appropriately trained staff can work with carers of people with dementia to help ensure that patients receive timely and person-centred treatment, and that the amount of time they spend in hospital is minimised. Future work: Future research could examine new ways to work with carers to co-produce aspects of inpatient care, and to explore the relationship between ethnicity and quality of care in patients with dementia. Funding: This project was funded by the National Institute for Health Research (NIHR) Health Services and Delivery Research programme and will be published in full in Health Services and Delivery Research; Vol. 8, No. 22. See the NIHR Journals Library website for further project information

Efficiency optimization and symmetry-breaking in a model of ciliary locomotion

A variety of swimming microorganisms, called ciliates, exploit the bending of a large number of small and densely-packed organelles, termed cilia, in order to propel themselves in a viscous fluid. We consider a spherical envelope model for such ciliary locomotion where the dynamics of the individual cilia are replaced by that of a continuous overlaying surface allowed to deform tangentially to itself. Employing a variational approach, we determine numerically the time-periodic deformation of such surface which leads to low-Reynolds locomotion with minimum rate of energy dissipation (maximum efficiency). Employing both Lagrangian and Eulerian points of views, we show that in the optimal swimming stroke, individual cilia display weak asymmetric beating, but that a significant symmetry-breaking occurs at the organism level, with the whole surface deforming in a wave-like fashion reminiscent of metachronal waves of biological cilia. This wave motion is analyzed using a formal modal decomposition, is found to occur in the same direction as the swimming direction, and is interpreted as due to a spatial distribution of phase-differences in the kinematics of individual cilia. Using additional constrained optimizations, as well as a constructed analytical ansatz, we derive a complete optimization diagram where all swimming efficiencies, swimming speeds, and amplitude of surface deformation can be reached, with the mathematically optimal swimmer, of efficiency one half, being a singular limit. Biologically, our work suggests therefore that metachronal waves may allow cilia to propel cells forward while reducing the energy dissipated in the surrounding fluid.Comment: 29 pages, 20 figure

Examining the Slavic Identity in the Middle Ages: Perception of Common Sense of Slavic Community in Polish and Bohemian Medieval Chronicles

The concept of Slavic solidarity is taken by some political or ideological movements as obviosity. In its later tradition it is based mainly on the language and cultural solidarity emphasised by romantic (and earlier) literature. The very origin of closeness of nowadays (and historical) Slavic nations is there traced to assumed bio-historical root. From the perspective of scientific analysis the examination of the whole term Slav should be done at first place. In medieval Polish and Bohemian chronicles we can observe a growing phenomenon of the identification with wider name Slav and with the common history of Slavs as well. In the Chronicle of Greater Poland, followed by chronicle of the Pulkava of Radenín and with the work of Jan Długosz was defined the model of biblical genealogy of Slavic nations. The solidarity was based mainly on the perception of similar languages and geographical closeness and was transformed in a literary way into blood relations. Reflection of this literary concept in foreing affairs is hardly to declare, but some dynastical representatives used the intelectual concept in a literary propaganda of their goals

Co-creating experiences through the use of arts in social work education

The inclusion of citizens in social work education was initiated over 30 years ago and continues to travel a ‘long and winding road’. Social work education in the UK faces increasing pressure from a range of stakeholders including citizens who use services, regulatory bodies and the media to demonstrate that newly qualified social workers are competent and uphold public trust. While social work education and practice within England and Wales draw on similar traditions in theory and practice, there are important differences in the national and institutional frameworks within which they operate. This article illustrates some of these differences through a focus on social work education provision in one English and one Welsh university. Drawing on the experience and views of the student participants, we examine the benefits of creative approaches that promote citizen involvement and suggest how European traditions can contribute to this process. We define key terms and summarize the literature, followed by presentation of the results and identification of the key learning. We identify that emancipatory models of education can encourage recognition of learners’ different strengths and can help to assist social work students’ readiness for practice. Finally, we acknowledge the need for cost-benefit outcomes research into if and how citizen coproduction influences subsequent service delivery

Boise State Open Educational Resources Staff Training

Join colleagues from the Library, eCampus, Learning Technology Solutions and the IDEA Shop for a morning of learning about OER. Goals include: 1) Participants will learn about OER and how we can help support faculty interested in adopting OER. 2) Participants will meet each other, learn what we do in our respective departments and how we can work together

Digital assemblages, information infrastructures, and mobile knowledge work

We theorize mobile knowledge workers’ uses of digital and material resources in support of their working practices. We do so to advance current conceptualizations of both “information infrastructures” and “digital assemblages” as elements of contemporary knowledge work. We focus on mobile knowledge workers as they are (increasingly) self-employed (e.g., as freelancers, entrepreneurs, temporary workers, and contractors), competing for work, and collaborating with others: one likely future of work that we can study empirically. To pursue their work, mobile knowledge workers draw together collections of commodity digital technologies or digital assemblages (e.g., laptops, phones, public WiFi, cloud storage, and apps), relying on a reservoir of knowledge about new and emergent means to navigate this professional terrain. We find that digital assemblages are created and repurposed by workers in their infrastructuring practices and in response to mobility demands and technological environments. In their constitution, they are generative to both collaborative and organizational goals. Building from this, we theorize that digital assemblages, as individuated forms of information infrastructure, sustain stability and internal cohesion even as they allow for openness and generativity

Diagnostics of solar flare energetic particles: neglected hard X-ray processes and neutron astronomy in the inner heliosphere

For work on my thesis dissertation, we have been studying some energetic processes in solar flares. On our work on hard X-ray (HXR) emission from flares, we have shown that non-thermal recombination emission can compare with the bremsstrahlung HXR flux for certain flare conditions. In this thesis, we show spectral features characteristic of non-thermal recombination HXR emission and suggest how it plays a signicant role in the flare HXR continuum, something that has been ignored in the past. It is important to note that these results could demand a reconsideration of the numbers of accelerated electrons since recombination can be much more efficient in producing HXR photons than bremsstrahlung. We go on to show that although nonthermal recombination is not likely to dominate the total HXR flux unless we consider extreme parameter regimes, it can still form a signicant proportion of the HXR flux for typical flare conditions, thereby remaining important for both spectral inversion and low energy electron cut-off diagnostic capabilities. In related work on diagnosing particle acceleration in flares, we also have an interest in studying solar neutrons. To this end, this thesis presents our work done with new-age neutron detectors developed by our colleagues at the University of New Hampshire. Using laboratory and simulated data from the detector to produce its response matrix, we then employ regularisation and deconvolution techniques to produce encouraging results for data inversion. As a corollary, we have been reconsidering the role of inverse Compton scattering (ICS) of photospheric photons. Gamma-ray observations clearly show the presence of 100 MeV electrons and positrons in the solar corona, by-products of GeV energy ions. We present results of ICS of solar flare photons taking proper account of radiation field geometry near the solar surface. If observed, such radiation would let us determine the number of secondary positrons produced in large flares, contributing to a full picture of ion acceleration and to predicting neutron fluxes to be encountered by future inner heliosphere space missions

The Travel Companion: Your guide to working with others for social outcomes

This is your guide to working together to achieve social purpose. The guide is for everyone working towards the creation of positive social impact in Australia and who wants to know whether and how they might work with others to make a difference. At the Centre for Social Impact (CSI) we recognise that there is an increasing focus on how people can create social change by working across organisations and even sectors but that navigating the literature, guides, tools and approaches can be overwhelming and challenging. The Travel Companion will help you understand what it entails to work with others and help you along your journey. It explores and explains the key topics, concepts, questions and principles related to working across organisations. If you are interested in understanding whether you need to work with others to achieve your social purpose, the approach to working together that might best suit your needs, and what can help you work together effectively, this guide is for you