281 research outputs found

    Impact of the Spruce Budworm (Lepidoptera: Tortricidae) on the Ottawa and Hiawatha National Forests, 1978-1980

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    The Michigan Impact Plot System was established during 1978 and 1979 to obtain a data base for quantifying the impact of the spruce budworm in the Ottawa and Hiawatha National Forests. The formulae used to estimate the mean, total, and associated standard errors of the various parameters at the national forest and forest district levels are presented. We present the 1978, 1979, and 1980 impact data for the following parameters; percent mortality, total dead volume. dead volume per ha, live volume per ha, defoliation ranking, frequency and extent of top-kill, and incidence of spruce budworm feeding on saplings and regenera- tion. Statistics from an annual inventory of 108 composite ground sampling units (CGSU) in 1978, and 136 CGSU\u27s in 1979 and 1980 provide a more precise estimate ofthe impact of the spruce budworm in Michigan\u27s Upper Peninsula than ha~ been available to date

    A Local Search Algorithm for the Min-Sum Submodular Cover Problem

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    We consider the problem of solving the Min-Sum Submodular Cover problem using local search. The Min-Sum Submodular Cover problem generalizes the NP-complete Min-Sum Set Cover problem, replacing the input set cover instance with a monotone submodular set function. A simple greedy algorithm achieves an approximation factor of 4, which is tight unless P=NP [Streeter and Golovin, NeurIPS, 2008]. We complement the greedy algorithm with analysis of a local search algorithm. Building on work of Munagala et al. [ICDT, 2005], we show that, using simple initialization, a straightforward local search algorithm achieves a (4+ϵ)(4+\epsilon)-approximate solution in time O(n3log(n/ϵ))O(n^3\log(n/\epsilon)), provided that the monotone submodular set function is also second-order supermodular. Second-order supermodularity has been shown to hold for a number of submodular functions of practical interest, including functions associated with set cover, matching, and facility location. We present experiments on two special cases of Min-Sum Submodular Cover and find that the local search algorithm can outperform the greedy algorithm on small data sets

    A Local Search Algorithm for the Min-Sum Submodular Cover Problem

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    Fast Atomic Charge Calculation for Implementation into a Polarizable Force Field and Application to an Ion Channel Protein

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    Polarization of atoms plays a substantial role in molecular interactions. Class I and II force fields mostly calculate with fixed atomic charges which can cause inadequate descriptions for highly charged molecules, for example, ion channels or metalloproteins. Changes in charge distributions can be included into molecular mechanics calculations by various methods. Here, we present a very fast computational quantum mechanical method, the Bond Polarization Theory (BPT). Atomic charges are obtained via a charge calculation method that depend on the 3D structure of the system in a similar way as atomic charges of ab initio calculations. Different methods of population analysis and charge calculation methods and their dependence on the basis set were investigated. A refined parameterization yielded excellent correlation of R=0.9967. The method was implemented in the force field COSMOS-NMR and applied to the histidine-tryptophan-complex of the transmembrane domain of the M2 protein channel of influenza A virus. Our calculations show that moderate changes of side chain torsion angle χ1 and small variations of χ2 of Trp-41 are necessary to switch from the inactivated into the activated state; and a rough two-side jump model of His-37 is supported for proton gating in accordance with a flipping mechanism

    Health system resilience: a critical review and reconceptualisation

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    This Viewpoint brings together insights from health system experts working in a range of settings. Our focus is on examining the state of the resilience field, including current thinking on definitions, conceptualisation, critiques, measurement, and capabilities. We highlight the analytical value of resilience, but also its risks, which include neglect of equity and of who is bearing the costs of resilience strategies. Resilience depends crucially on relationships between system actors and components, and—as amply shown during the COVID-19 pandemic—relationships with wider systems (eg, economic, political, and global governance structures). Resilience is therefore connected to power imbalances, which need to be addressed to enact the transformative strategies that are important in dealing with more persistent shocks and stressors, such as climate change. We discourage the framing of resilience as an outcome that can be measured; instead, we see it emerge from systemic resources and interactions, which have effects that can be measured. We propose a more complex categorisation of shocks than the common binary one of acute versus chronic, and outline some of the implications of this for resilience strategies. We encourage a shift in thinking from capacities towards capabilities—what actors could do in future with the necessary transformative strategies, which will need to encompass global, national, and local change. Finally, we highlight lessons emerging in relation to preparing for the next crisis, particularly in clarifying roles and avoiding fragmented governance

    Incorporating comorbidity within risk adjustment for UK pediatric cardiac surgery

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    INTRODUCTION: When considering early survival rates after pediatric cardiac surgery it is essential to adjust for risk linked to case complexity. An important but previously less well understood component of case mix complexity is comorbidity. METHODS: National congenital heart diseases audit (NCHDA) data representing all pediatric cardiac surgery procedures undertaken in the United Kingdom and Ireland between 2009 and 2014 was used to develop and test groupings for comorbidity and additional non procedure based risk factors within a risk adjustment model for 30-day mortality. A mixture of expert consensus based opinion and empiric statistical analyses were used to define and test the new comorbidity groups. RESULTS: The study dataset consisted of 21,838 pediatric cardiac surgical procedure episodes in 18,834 patients with 539 deaths (raw 30-day mortality rate 2.5%). In addition to surgical procedure type, primary cardiac diagnosis, univentricular status, age, weight, procedure type (bypass, non-bypass or hybrid) and era, the new risk factor groups of: non Downs congenital anomalies, acquired comorbidities, increased severity of illness indicators (such as pre-operative mechanical ventilation or circulatory support) and additional cardiac risk factors (such as heart muscle conditions and raised pulmonary arterial pressure) all independently increased the risk of operative mortality. DISCUSSION: In an era of low mortality rates across a wide range of operations, non-procedure based risk factors form a vital element of risk adjustment and their presence leads to wide variations in the predicted risk of a given operation

    A Structurally Flexible Halide Solid Electrolyte with High Ionic Conductivity and Air Processability

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    In this work, a structurally revivable, chloride-ion conducting solid electrolyte (SE), CsSn0.9_{0.9}In0.067_{0.067}Cl3_3, with a high ionic conductivity of 3.45 × 104^{−4} S cm1^{−1} at 25 °C is investigated. The impedance spectroscopy, density functional theory, solid-state 35^{35}Cl NMR, and electron paramagnetic resonance studies collectively reveal that the high Cl^− ionic mobility originates in the flexibility of the structural building blocks, Sn/InCl6_6 octahedra. The vacancy-dominated Cl^− ion diffusion encompasses co-ordinated Sn/In(Cl) site displacements that depend on the exact stoichiometry, and are accompanied by changes in the local magnetic moments. Owing to these promising properties, the suitability of the CsSn0.9_{0.9}In0.067_{0.067}Cl3_3, as an electrolyte is demonstrated by designing all-solid-state batteries, with different anodes and cathodes. The comparative investigation of interphases with Li, Li–In, Mg, and Ca anodes reveals different levels of reactivity and interphase formation. The CsSn0.9_{0.9}In0.067_{0.067}Cl3_3 demonstrates an excellent humidity tolerance (up to 50% relative humidity) in ambient air, maintaining high structural integrity without compromises in ionic conductivity, which stands in contrast to commercial halide-based lithium conductors. The discovery of a halide perovskite conductor, with air processability and structure revival ability paves the way for the development of advanced air processable SEs, for next-generation batteries

    Health system resilience: a critical review and reconceptualisation

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    Sophie Witter - ORCID: 0000-0002-7656-6188 https://orcid.org/0000-0002-7656-6188Alastair Ager - ORCID: 0000-0002-9474-3563 https://orcid.org/0000-0002-9474-3563This Viewpoint brings together insights from health system experts working in a range of settings. Our focus is on examining the state of the resilience field, including current thinking on definitions, conceptualisation, critiques, measurement, and capabilities. We highlight the analytical value of resilience, but also its risks, which include neglect of equity and of who is bearing the costs of resilience strategies. Resilience depends crucially on relationships between system actors and components, and—as amply shown during the COVID-19 pandemic—relationships with wider systems (eg, economic, political, and global governance structures). Resilience is therefore connected to power imbalances, which need to be addressed to enact the transformative strategies that are important in dealing with more persistent shocks and stressors, such as climate change. We discourage the framing of resilience as an outcome that can be measured; instead, we see it emerge from systemic resources and interactions, which have effects that can be measured. We propose a more complex categorisation of shocks than the common binary one of acute versus chronic, and outline some of the implications of this for resilience strategies. We encourage a shift in thinking from capacities towards capabilities—what actors could do in future with the necessary transformative strategies, which will need to encompass global, national, and local change. Finally, we highlight lessons emerging in relation to preparing for the next crisis, particularly in clarifying roles and avoiding fragmented governance.This Viewpoint has no specific funding, but SW's time was supported by the ReBUILD for Resilience research consortium, funded by the UK Foreign, Commonwealth & Development Office.https://doi.org/10.1016/S2214-109X(23)00279-611pubpub

    What are the important morbidities associated with paediatric cardiac surgery? A mixed methods study.

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    OBJECTIVES: Given the current excellent early mortality rates for paediatric cardiac surgery, stakeholders believe that this important safety outcome should be supplemented by a wider range of measures. Our objectives were to prospectively measure the incidence of morbidities following paediatric cardiac surgery and to evaluate their clinical and health-economic impact over 6 months. DESIGN: The design was a prospective, multicentre, multidisciplinary mixed methods study. SETTING: The setting was 5 of the 10 paediatric cardiac surgery centres in the UK with 21 months recruitment. PARTICIPANTS: Included were 3090 paediatric cardiac surgeries, of which 666 patients were recruited to an impact substudy. RESULTS: Families and clinicians prioritised:Acute neurological event, unplanned re-intervention, feeding problems, renal replacement therapy, major adverse events, extracorporeal life support, necrotising enterocolitis, postsurgical infection and prolonged pleural effusion or chylothorax.Among 3090 consecutive surgeries, there were 675 (21.8%) with at least one of these morbidities. Independent risk factors for morbidity included neonatal age, complex heart disease and prolonged cardiopulmonary bypass (p<0.001). Among patients with morbidity, 6-month survival was 88.2% (95% CI 85.4 to 90.6) compared with 99.3% (95% CI 98.9 to 99.6) with none of the morbidities (p<0.001). The impact substudy in 340 children with morbidity and 326 control children with no morbidity indicated that morbidity-related impairment in quality of life improved between 6 weeks and 6 months. When compared with children with no morbidities, those with morbidity experienced a median of 13 (95% CI 10.2 to 15.8, p<0.001) fewer days at home by 6 months, and an adjusted incremental cost of £21 292 (95% CI £17 694 to £32 423, p<0.001). CONCLUSIONS: Evaluation of postoperative morbidity is more complicated than measuring early mortality. However, tracking morbidity after paediatric cardiac surgery over 6 months offers stakeholders important data that are of value to parents and will be useful in driving future quality improvement
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