46 research outputs found

    A General Statement of Structured Singular Value Concepts

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    Some key concepts of strucred singular value theory for the stability and performance-robustness analysis of linear time-invariant multivariable systems are stated. Using a set-invariance principle, the theory is then generalized to allow for nonlinear and/or time-varying nominal systems and uncertainties. The general theory is then re-specialized to the case of nominally linear time-invariant systems subject to L2-induced-norm bounded uncertainties

    Cost Efectiveness of Ambulatory Blood Pressure Monitoring Compared with Home or Clinic Blood Pressure Monitoring for Diagnosing Hypertension in Australia

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    Objectives The aim of this study was to evaluate the cost effectiveness of ambulatory blood pressure monitoring (ABPM) compared with home blood pressure monitoring (HBPM) and clinic blood pressure monitoring (CBPM) in diagnosing hypertension in Australia. Methods A cohort-based Markov model was built from the Payer’s perspective (Australian government) comparing lifetime costs and effectiveness of ABPM, HBPM and CBPM in people aged ≥ 35 years with suspected hypertension who have a CBPM between ≥ 140/90 mmHg and ≤ 180/110 mmHg using a sphygmomanometer and have not yet commenced antihypertensive treatment. The main outcome measures were incremental cost-effectiveness ratio (ICER) assessing cost per quality-adjusted life-year (QALY) and life-years (LYs) gained by ABPM versus HBPM and CBPM. Cost was measured in Australian dollars (A).ResultsOveralifetimemodel,ABPMhadlowertotalcosts(A). Results Over a lifetime model, ABPM had lower total costs (A8,491) compared with HBPM (A9,648)andCBPM(A9,648) and CBPM (A10,206) per person. ABPM was associated with a small but significant improvement in the quality and quantity of life for people with suspected hypertension with 12.872 QALYs and 17.449 LYs compared with 12.857 QALYs and 17.433 LYs with HBPM, and 12.850 QALYs and 17.425 LYs with CBPM. In the base-case analysis, ABPM dominated HBPM and CBPM. In scenario analyses, at 100% specificity of HBPM, ABPM no longer remained cost effective at a A$50,000/QALY threshold. However, in probabilistic sensitivity analysis, over 10,000 iterations, ABPM remained dominant. Conclusion ABPM was the dominant strategy for confirming the diagnosis of hypertension among Australian adults aged ≥ 35 years old with suspected hypertension. The findings of this study are important for reimbursement decision makers to support policy change and for clinicians to make practice changes consistent with ABPM recommendations in primary care

    Beach recovery from extreme storm activity during the 2013–14 winter along the Atlantic coast of Europe

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    The storm sequence of the 2013–14 winter left many beaches along the Atlantic coast of Europe in their most eroded state for decades. Understanding how beaches recover from such extreme events is essential for coastal managers, especially in light of potential regional increases in storminess due to climate change. Here we analyse a unique dataset of decadal beach morphological changes along the west coast of Europe to investigate the post-2013–14 winter recovery. We show that the recovery signature is site specific and multi-annual, with one studied beach fully recovered after 2 years, and the others only partially recovered after 4 years. During the recovery phase, winter waves primarily control the timescales of beach recovery, as energetic winter conditions stall the recovery process whereas moderate winter conditions accelerate it. This inter-annual variability is well correlated with climate indices. On exposed beaches, an equilibrium model showed significant skill in reproducing the post-storm recovery and thus can be used to investigate the recovery process in more detail. © 2018 John Wiley & Sons, Ltd

    Uncommon worlds: toward an ecological aesthetics of childhood in the Anthropocene

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    In addressing the need for a more robust engagement with aesthetics in posthumanist studies of childhood and nature, this chapter makes some tentative steps towards an ecological aesthetics of childhood that is responsive to Whitehead’s speculative philosophy. In doing so, the chapter takes an alternative theoretical approach from much of the ‘common worlds’ scholarship that has emerged in recent years, while making the case for a new aesthetics of childhood that is responsive to the accelerating social, technological, and environmental changes of the Anthropocene epoch. Our approach foregrounds the singularity of children’s aesthetic experiences as relational-qualitative ‘intensities’ that alter the fabric of nature as an extensive continuum held in common. We therefore argue that every moment in the life of a child is an uncommon and unrepeatable occasion through which the common world of nature is felt, perceived, and experienced differently. This eco-aesthetic approach is developed further through the analysis of photographs taken by children as part of the Climate Change and Me project, which has mapped children and young people’s affective responses to climate change over a period of three years in New South Wales, Australia. Rather than working with images as representations or analogic signifiers for children’s experience, we analyse how each photograph co-implicates children’s bodies and environments through affective vectors of feeling, or ‘prehensions’. This leads us to reframe aesthetic notions of image, sensibility, perception, and causality in relational terms, while also acknowledging the individuation of childhood experiences as ‘creaturely becomings’ that produce new potentials for environmental thought and behaviour

    The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

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    INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

    Nonlinear Six-Degree-of-Freedom Aircraft Trim

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    Robust control design for a flexible beam using a distributed-parameter H∞-method

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    ©1989 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or distribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.DOI: 10.1109/CDC.1989.70664Presented at the 28th Conference on Decision and Control, 13-15 Dec 1989, Tampa, FLA skew Toeplitz theory is used to derive the H∞-optimal controller for a weighted mixed sensitivity design for a free-free Euler-Bernoulli beam. On the basis of the structure of the optimal controller, low-order, suboptimal, finite-dimensional, linear, time-invariant controllers are designed for the beam with and without a pure time delay
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