2,355 research outputs found

    Alkali oxide-tantalum, niobium and antimony oxide ionic conductors

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    The phase equilibrium relations of four systems were investigated in detail. These consisted of sodium and potassium antimonates with antimony oxide and tantalum and niobium oxide with rubidium oxide as far as the ratio 4Rb2O:llB2O5 (B=Nb, Ta). The ternary system NaSbO3-Sb2O4-NaF was investigated extensively to determine the actual composition of the body centered cubic sodium antimonate. Various other binary and ternary oxide systems involving alkali oxides were examined in lesser detail. The phases synthesized were screened by ion exchange methods to determine mobility of the mobility of the alkali ion within the niobium, tantalum or antimony oxide (fluoride) structural framework. Five structure types warranted further investigation; these structure types are (1) hexagonal tungsten bronze (HTB), (2) pyrochlore, (3) the hybrid HTB-pyrochlore hexagonal ordered phases, (4) body centered cubic antimonates and (5) 2K2O:3Nb2O5. Although all of these phases exhibit good ion exchange properties only the pyrochlore was prepared with Na(+) ions as an equilibrium phase and as a low porosity ceramic. Sb(+3) in the channel interferes with ionic conductivity in this case, although relatively good ionic conductivity was found for the metastable Na(+) ion exchanged analogs of RbTa2O5F and KTaWO6 pyrochlore phases

    Physical Education and Blood Lipid Concentrations in Children: The LOOK Randomized Cluster Trial

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    BACKGROUND AND OBJECTIVES Elevated blood lipids during childhood are predictive of dyslipidemia in adults. Although obese and inactive children have elevated values, any potentially protective role of elementary school physical education is unknown. Our objective was to determine the effect of a modern elementary school physical education (PE) program on the blood lipid concentrations in community-based children. METHODS In this cluster-randomized controlled trial, 708 healthy children (8.1±0.3 years, 367 boys) in 29 schools were allocated to either a 4-year intervention program of specialist-taught PE (13 schools) or to a control group of the currently practiced PE conducted by generalist classroom teachers. Fasting blood lipids were measured at ages 8, 10, and 12 years and intervention and control class activities were recorded. RESULTS Intervention classes included more fitness work and more moderate and vigorous physical activity than control classes (both p3.36mmol.L(-1),130 mg/dL) was lower in the intervention than control group (14% vs. 23%, p = 0.02). There was also an intervention effect on mean LDL-C across all boys (reduction of 9.6% for intervention v 2.8% control, p = 0.02), but not girls (p = 0.2). The intervention effect on total cholesterol mirrored LDL-C, but there were no detectable 4-year intervention effects on high-density lipoprotein cholesterol or triglycerides. CONCLUSIONS The PE program delivered by specialist teachers over four years in elementary school reduced the incidence of elevated LDL-C in boys and girls, and provides a means by which early preventative practices can be offered to all children. TRIAL REGISTRATION Australia New Zealand Clinical Trial Registry ANZRN12612000027819 https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=347799.Sources of funding were The Commonwealth Education Trust (New Zealand House, London, UK) (http://www.commonwealth.org.uk/) and the Canberra Hospital Salaried Staff Specialists Fund (http://healthresearch.anu.edu.au/documents/PPFVACATION/ppf-major-info-2012.pdf). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

    A qualitative study of professional and carer perceptions of the threats to safe hospital discharge for stroke and hip fracture patients in the English National Health Service

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    Background: Hospital discharge is a vulnerable transitional stage in patient care. This qualitative study investigated the views of healthcare professionals and patients about the threats to safe hospital discharge with aim of identifying contributory and latent factors. The study was undertaken in two regional health and social care systems in the English National Health Service, each comprising three acute hospitals, community and primary care providers and municipal social care services. The study focused on the threats to safe discharge for hip fracture and stroke patients as exemplars of complex care transitions. Methods: A qualitative study involving narrative interviews with 213 representative stakeholders and professionals involved in discharge planning and care transition activities. Narratives were analysed in line with ‘systems’ thinking to identify proximal (active) and distal (latent) factors, and the relationships between them. Results: Three linked categories of commonly and consistently identified threat to safe discharge were identified:(1) ‘direct’ patient harms comprising falls, infection, sores and ulceration, medicines-related issues, and relapse; (2) proximal ‘contributing’ factors including completion of tests, assessment of patient, management of equipment and medicines, care plan, follow-up care and patient education; and distal ‘latent’ factors including discharge planning, referral processes, discharge timing, resources constraints, and organisational demands. Conclusion: From the perspective of stakeholders, the study elaborates the relationship between patient harms and systemic factors in the context of hospital discharge. It supports the importance of communication and collaboration across occupational and organisational boundaries, but also the challenges to supporting such communication with the inherent complexity of the care system

    Cognitive Status, Initiation of Lifestyle Changes and Medication Adherence after Acute Coronary Syndrome: TRACE-CORE (Transitions, Risks, and Actions in Coronary Events- Center for Outcomes Research and Education)

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    Background: Lifestyle changes and medication adherence are often recommended to patients after acute coronary syndrome (ACS) as secondary prevention strategies. However, the impact of cognitive impairment (CI) on these secondary prevention strategies following ACS has not been examined. Methods: Cognitive status of 1374 patients with ACS from six hospitals in Massachusetts and Georgia enrolled in the ongoing TRACE-CORE (Transitions, Risks, and Actions in Coronary Events- Center for Outcomes Research and Education) study was assessed during hospitalization using the 41-point Telephone Interview for Cognitive Status (TICS). Information on recommendation and initiation of changes to diet, exercise, tobacco and alcohol use, stress, and cardiac rehabilitation attendance was collected through self-report one month after discharge. Medication adherence was assessed using the 8-item Morisky Scale. Among patients who reported receiving a recommendation for a lifestyle change, we modeled associations between CI and initiation of lifestyle changes and medication adherence, adjusting for demographics via logistic regression. Results: Mean age of participants was 63.0±11.1 years, 67% were male and 79% white; 526 (38.3%) screened positive for CI (TICS score ≤30) during hospitalization. Screening positive for CI was associated with being older, male, non-white, and less educated. Patients with CI more frequently received a recommendation to reduce alcohol use (25% vs. 16% of drinkers, p=.003) but were referred less often to a cardiac rehabilitation program (45% vs. 61%, p=.01). Among patients referred to cardiac rehabilitation (n=743), those with CI at baseline were less likely to report rehabilitation attendance at 1-month (OR= 0.70, 95%CI 0.50-0.97) compared to patients with normal cognitive function. Initiation of other lifestyle changes and medication adherence did not differ by cognitive status. Conclusions: CI is common among patients hospitalized for ACS and is associated with recommendation and initiation of certain lifestyle changes, making it an important factor to consider during the peri-discharge period

    The adult heart responds to increased workload with physiologic hypertrophy, cardiac stem cell activation, and new myocyte formation

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    Aims It is a dogma of cardiovascular pathophysiology that the increased cardiac mass in response to increased workload is produced by the hypertrophy of the pre-existing myocytes. The role, if any, of adult-resident endogenous cardiac stem/progenitor cells (eCSCs) and new cardiomyocyte formation in physiological cardiac remodelling remains unexplored. Methods and results In response to regular, intensity-controlled exercise training, adult rats respond with hypertrophy of the pre-existing myocytes. In addition, a significant number (∼7%) of smaller newly formed BrdU-positive cardiomyocytes are produced by the exercised animals. Capillary density significantly increased in exercised animals, balancing cardiomyogenesis with neo-angiogenesis. c-kitpos eCSCs increased their number and activated state in exercising vs. sedentary animals. c-kitpos eCSCs in exercised hearts showed an increased expression of transcription factors, indicative of their commitment to either the cardiomyocyte (Nkx2.5pos) or capillary (Ets-1pos) lineages. These adaptations were dependent on exercise duration and intensity. Insulin-like growth factor-1, transforming growth factor-β1, neuregulin-1, bone morphogenetic protein-10, and periostin were significantly up-regulated in cardiomyocytes of exercised vs. sedentary animals. These factors differentially stimulated c-kitpos eCSC proliferation and commitment in vitro, pointing to a similar role in vivo. Conclusion Intensity-controlled exercise training initiates myocardial remodelling through increased cardiomyocyte growth factor expression leading to cardiomyocyte hypertrophy and to activation and ensuing differentiation of c-kitpos eCSCs. This leads to the generation of new myocardial cells. These findings highlight the endogenous regenerative capacity of the adult heart, represented by the eCSCs, and the fact that the physiological cardiac adaptation to exercise stress is a combination of cardiomyocyte hypertrophy and hyperplasia (cardiomyocytes and capillaries)

    Tropical dry forest response to nutrient fertilization: a model validation and sensitivity analysis

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    Soil nutrients, especially nitrogen (N) and phosphorus (P), regulate plant growth and hence influence carbon fluxes between the land surface and atmosphere. However, how forests adjust biomass partitioning to leaves, wood, and fine roots in response to N and/or P fertilization remains puzzling. Recent work in tropical forests suggests that trees increase fine root production under P fertilization, but it is unclear whether mechanistic models can reproduce this dynamic. In order to better understand mechanisms governing nutrient effects on plant allocation and improve models, we used the nutrient-enabled ED2 model to simulate a fertilization experiment being conducted in a secondary tropical dry forest in Costa Rica. We evaluated how different allocation parameterizations affected model performance. These parameterizations prescribed a linear relationship between relative allocation to fine roots and soil P concentrations. The slope of the linear relationship was allowed to be positive, negative, or zero. Some parameterizations realistically simulated leaf, wood, and fine root production, and these parameterizations all assumed a positive relationship between relative allocation to fine roots and soil P concentration. Model simulations of a 30-year timeframe indicated strong sensitivity to parameterization and fertilization treatment. Without P fertilization, the simulated aboveground biomass (AGB) accumulation was insensitive to the parameterization. With P fertilization, the model was highly sensitive to the parameterization and the greatest AGB accumulation occurred when relative allocation to fine roots was independent of soil P. Our study demonstrates the need for simultaneous measurements of leaf, wood, and fine root production in nutrient fertilization experiments and for longer-term experiments. Models that do not accurately represent allocation to fine roots may be highly biased in their simulations of AGB, especially on multi-decadal timescales.</p

    A joint individual-based model coupling growth and mortality reveals that tree vigor is a key component of tropical forest dynamics

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    Tree vigor is often used as a covariate when tree mortality is predicted from tree growth in tropical forest dynamic models, but it is rarely explicitly accounted for in a coherent modeling framework. We quantify tree vigor at the individual tree level, based on the difference between expected and observed growth. The available methods to join nonlinear tree growth and mortality processes are not commonly used by forest ecologists so that we develop an inference methodology based on an MCMC approach, allowing us to sample the parameters of the growth and mortality model according to their posterior distribution using the joint model likelihood. We apply our framework to a set of data on the 20-year dynamics of a forest in Paracou, French Guiana, taking advantage of functional trait-based growth and mortality models already developed independently. Our results showed that growth and mortality are intimately linked and that the vigor estimator is an essential predictor of mortality, highlighting that trees growing more than expected have a far lower probability of dying. Our joint model methodology is sufficiently generic to be used to join two longitudinal and punctual linked processes and thus may be applied to a wide range of growth and mortality models. In the context of global changes, such joint models are urgently needed in tropical forests to analyze, and then predict, the effects of the ongoing changes on the tree dynamics in hyperdiverse tropical forests. (Résumé d'auteur

    Unlearning and patient safety

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    This chapter adds to the growing body of literature on unlearning by contributing a model applicable to the context of professional organisations, and more specifically to healthcare and patient safety. An overview of the global patient safety agenda is described and a gap in implementing sustained safety improvement identified. The UK’s efforts to bridge this gap in patient safety by transforming their NHS into a ‘learning organisation’ are discussed. The unlearning literature is reviewed and an updated model of unlearning conceptualized that contains three dimensions relevant to the study of professionals: cognitive, cultural and political. As a research agenda, this chapter provides a starting point for thinking about how unlearning can be studied in organisations; establishing a theoretical foundation for future study

    Angina Characteristics as Predictors of Trajectories of Quality of Life Following Acute Coronary Syndrome in the Transitions, Risks and Actions in Coronary Events-Center for Outcomes Research and Education cohort (TRACE-CORE)

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    BACKGROUND: To describe longitudinal trajectories of health-related quality of life (HRQoL) after hospitalization with an acute coronary syndrome (ACS), their associations with baseline angina characteristics, and associations with anxiety, depression, and cognitive impairment. METHODS: TRACE-CORE participants (N=1,613) completed the SF-36 during hospitalization for ACS and 1, 3, & 6 months post-discharge. Latent growth curves identified trajectories of physical and mental components of HRQOL (MCS and PCS) and sequential multiple logistic regression estimated associations between trajectories and angina characteristics. RESULTS: Participants (N=1613) had mean age 63.3 (SD 11.4) years, 33.0% female, and 78.2% non-Hispanic white. We identified 2 MCS trajectories: AVERAGE and IMPAIRED HRQoL. The majority of participants (81.0%) had AVERAGE MCS at baseline (mean MCS 53.6) and slight improvement in scores over time. A minority (19.0%) had IMPAIRED HRQoL at baseline (mean MCS 36.7) and slight improvement in scores over time. We identified 2 similar PCS trajectories with similar patterns of scores over time: AVERAGE (71.1%) and IMPAIRED (28.9%) HRQoL at baseline. Adjusting for demographics & comorbidities, patients with less severe baseline angina were more likely to have AVERAGE MCS (odds ratio [OR]/10 unit change in severity 1.1) and PCS (OR 1.1) trajectories, and similarly for less frequent angina (MCS OR 1.2; PCS OR 1.3). The associations of MCS trajectory with severity and frequency lost significance after adjusting for psychosocial factors, whereas the PCS associations remained significant [All p \u3c 0.05 unless noted]. CONCLUSIONS: About 1/3 of patients exhibited impaired 6-month HRQoL trajectories, which can be predicted by angina characteristics. Psychosocial factors may explain the prediction of mental, not physical, trajectories. Interventions to improve HRQoL after ACS should consider psychosocial factors and angina
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