1,274 research outputs found

    Advection of vector fields by chaotic flows

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    We have introduced a new transfer operator for chaotic flows whose leading eigenvalue yields the dynamo rate of the fast kinematic dynamo and applied cycle expansion of the Fredholm determinant of the new operator to evaluation of its spectrum. The theory hs been tested on a normal form model of the vector advecting dynamical flow. If the model is a simple map with constant time between two iterations, the dynamo rate is the same as the escape rate of scalar quantties. However, a spread in Poincar\'e section return times lifts the degeneracy of the vector and scalar advection rates, and leads to dynamo rates that dominate over the scalar advection rates. For sufficiently large time spreads we have even found repellers for which the magnetic field grows exponentially, even though the scalar densities are decaying exponentially.Comment: 12 pages, Latex. Ask for figures from [email protected]

    Personal pack display and active smoking at outdoor café strips: assessing the impact of plain packaging 1 year postimplementation

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    Aims: We observed tobacco pack display and smoking at outdoor venues over three summers to assess changes in their prevalence following Australia's introduction of plain tobacco packaging with larger pictorial health warnings. Methods: Between January and April 2012 (preplain packaging (PP)), 2013 (early post-PP) and 2014 (1 year post-PP), we counted patrons, smokers and tobacco packs at cafĂ©s, restaurants and bars with outdoor seating. Pack type (branded, plain or unknown) and orientation were noted. Rates of active smoking, pack display and pack orientation were analysed using multilevel Poisson regression. Results: Prevalence of pack display among patrons declined from pre-PP (1 pack per 8.7 patrons) to early post-PP (1 pack per 10.4), and remained low 1 year post-PP (1 pack per 10.3). This appeared to be driven by a sustained decline in active smoking post-PP (pre-PP: 8.4% of patrons were smoking; early post-PP: 6.4%; 1 year post-PP: 6.8%). Notably, active smoking declined more in venues with children present than in those without. While early post-PP, plain packs were less often displayed face-up (74.0%) and more often concealed (8.9%) than branded packs pre-PP (face-up: 85.2%; concealed: 4.0%), this was not sustained 1 year post-PP (face-up: 85.7%; concealed: 4.4%). Also, external case use increased from pre-PP (1.2%) to early post-PP (3.5%), but returned to pre-PP levels 1 year post-PP (1.9%). Conclusions: This study demonstrated a sustained reduction in visibility of tobacco products and smoking in public, particularly in the presence of children, from pre-PP to 1 year post-PP. This effect is likely to reduce smoking-related social norms, thereby weakening an important influence on smoking uptake and better supporting quit attempts.Meghan Zacher, Megan Bayly, Emily Brennan, Joanne Dono, Caroline Miller, Sarah Durkin, Michelle Scollo, Melanie Wakefiel

    Enablers and barriers to treatment adherence in heterozygous familial hypercholesterolaemia : a qualitative evidence synthesis

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    This evidence synthesis is funded by the National Institute for Health Research NIHR Bristol Biomedical Research Centre (Nutrition theme) at University Hospitals Bristol NHS Foundation Trust and The University of Bristol.Peer reviewedPublisher PD

    Evidence of strong small-scale population structure in the Antarctic freshwater copepod Boeckella poppei in lakes on Signy Island, South Orkney Islands

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    Environmental conditions were particularly severe during the Last Glacial Maximum, altering the distribution of the Southern Hemisphere biota, particularly at higher latitudes. The copepod Boeckella poppei is the only macroscopic continental invertebrate species known to be distributed today across the three main biogeographic regions in Antarctica as well as in southern South America. Signy Island (South Orkney Islands) is a unique location for the study of Antarctic freshwater ecosystems due to its location and geographic isolation; it contains 17 lakes in several low altitude catchments. We conducted phylogeographic and demographic analyses using the cox1 gene on 84 individuals of B. poppei from seven lakes across Signy Island. We recorded low levels of genetic diversity and a strong genetic differentiation signal between the eastern and western valleys within the island. Phylogeographic structure and demographic inference analyses suggested at least one asymmetrical dispersal event from west to east. Demographic inference detected a strong signal of population growth during the deglaciation process, which may have followed either (1) a strong genetic bottleneck due to a reduction in population size during the last glacial period, or (2) a founder effect associated with postglacial recolonization of Signy Island from elsewhere. The genetic architecture of this island's populations of B. poppei shows that historical events, rather than continuous dispersal events, likely played a major role in the species' current distribution. Finally, our study considers possible mechanisms for dispersal and colonization success of the most dominant species in the Antarctic freshwater community

    On waiting for something to happen

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    This paper seeks to examine two particular and peculiar practices in which the mediation of apparently direct encounters is made explicit and is systematically theorized: that of the psychoanalytic dialogue with its inward focus and private secluded setting, and that of theatre and live performance, with its public focus. Both these practices are concerned with ways in which “live encounters” impact on their participants, and hence with the conditions under which, and the processes whereby, the coming-together of human subjects results in recognizable personal or social change. Through the rudimentary analysis of two anecdotes, we aim to think these encounters together in a way that explores what each borrows from the other, the psychoanalytic in the theatrical, the theatrical in the psychoanalytic, figuring each practice as differently committed to what we call the “publication of liveness”. We argue that these “redundant” forms of human contact continue to provide respite from group acceptance of narcissistic failure in the post-democratic era through their offer of a practice of waiting

    Integration of primary care and palliative care services to improve equality and equity at the end-of-life:Findings from realist stakeholder workshops

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    Background: Inequalities in access to palliative and end of life care are longstanding. Integration of primary and palliative care has the potential to improve equity in the community. Evidence to inform integration is scarce as research that considers integration of primary care and palliative care services is rare. Aim: To address the questions: ‘how can inequalities in access to community palliative and end of life care be improved through the integration of primary and palliative care, and what are the benefits?’ Design: A theory-driven realist inquiry with two stakeholder workshops to explore how, when and why inequalities can be improved through integration. Realist analysis leading to explanatory context(c)-mechanism(m)-outcome(o) configurations(c) (CMOCs). Findings: A total of 27 participants attended online workshops (July and September 2022): patient and public members (n=6), commissioners (n=2), primary care (n=5) and specialist palliative care professionals (n=14). Most were White British (n=22), other ethnicities were Asian (n=3), Black African (n=1) and British mixed race (n=1). Power imbalances and racism hinder people from ethnic minority backgrounds accessing current services. Shared commitment to addressing these across palliative care and primary care is required in integrated partnerships. Partnership functioning depends on trusted relationships and effective communication, enabled by co-location and record sharing. Positive patient experiences provide affirmation for the multi-disciplinary team, grow confidence and drive improvements. Conclusions: Integration to address inequalities needs recognition of current barriers. Integration grounded in trust, faith and confidence can lead to a cycle of positive patient, carer and professional experience. Prioritising inequalities as whole system concern is required for future service delivery and research. <br/

    Intracellular connections between basal bodies promote the coordinated behavior of motile cilia

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    Hydrodynamic flow produced by multiciliated cells is critical for fluid circulation and cell motility. Hundreds of cilia beat with metachronal synchrony for fluid flow. Cilia-driven fluid flow produces extracellular hydrodynamic forces that cause neighboring cilia to beat in a synchronized manner. However, hydrodynamic coupling between neighboring cilia is not the sole mechanism that drives cilia synchrony. Cilia are nucleated by basal bodies (BBs) that link to each other and to the cell\u27s cortex via BB-associated appendages. The intracellular BB and cortical network is hypothesized to synchronize ciliary beating by transmitting cilia coordination cues. The extent of intracellular ciliary connections and the nature of these stimuli remain unclear. Moreover, how BB connections influence the dynamics of individual cilia has not been established. We show by focused ion beam scanning electron microscopy imaging that cilia are coupled both longitudinally and laterally in the ciliat

    Size-Dependent Transition to High-Dimensional Chaotic Dynamics in a Two-Dimensional Excitable Medium

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    The spatiotemporal dynamics of an excitable medium with multiple spiral defects is shown to vary smoothly with system size from short-lived transients for small systems to extensive chaos for large systems. A comparison of the Lyapunov dimension density with the average spiral defect density suggests an average dimension per spiral defect varying between three and seven. We discuss some implications of these results for experimental studies of excitable media.Comment: 5 pages, Latex, 4 figure

    Queering Development? The Unsettling Geographies of South–South Cooperation

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    This paper deploys queer theory as a way of approaching South–South Cooperation (SSC). It examines the ways in which Southern development partners are not simply up-ending the long-standing spatialities, imaginaries and identities (re)produced through the mainstream international development regime, but queering terminologies and definitions, while presenting themselves in fluid ways, enrolling different identities and attributes in different places and to different audiences. At the same time, a queer lens reveals the (re)inscription of gendered, sexualised and racialised identities and hierarchies through the relationships, intimacies and practices of SSC. The paper proposes that queer theory can offer productive insights into the complex and compelling phenomenon of SSC, and the transgressive challenges to the postcolonial hierarchies and binaries of “traditional” international development
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