4,429 research outputs found

    Coordination of Foliar and Wood Anatomical Traits Contributes to Tropical Tree Distributions and Productivity along the Malay-Thai Peninsula

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    Drought is a critical factor in plant species distributions. Much research points to its relevance even in moist tropical regions. Recent studies have begun to elucidate mechanisms underlying the distributions of tropical tree species with respect to drought; however, how such desiccation tolerance mechanisms correspond with the coordination of hydraulic and photosynthetic traits in determining species distributions with respect to rainfall seasonality deserves attention. In the present study, we used a common garden approach to quantify inherent differences in wood anatomical and foliar physiological traits in 21 tropical tree species with either widespread (occupying both seasonal and aseasonal climates) or southern (restricted to aseasonal forests) distributions with respect to rainfall seasonality. Use of congeneric species pairs and phylogenetically independent contrast analyses allowed examination of this question in a phylogenetic framework. Widespread species opted for wood traits that provide biomechanical support and prevent xylem cavitation and showed associated reductions in canopy productivity and consequently growth rates compared with southern species. These data support the hypothesis that species having broader distributions with respect to climatic variability will be characterized by traits conducive to abiotic stress tolerance. This study highlights the importance of the well-established performance vs. stress tolerance trade-off as a contributor to species distributions at larger scales

    Evidence, theory and context - using intervention mapping to develop a school-based intervention to prevent obesity in children

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    © 2011 Lloyd et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Only limited data are available on the development and feasibility piloting of school-based interventions to prevent and reduce obesity in children. Clear documentation of the rationale, process of development and content of such interventions is essential to enable other researchers to understand why interventions succeed or fail

    Ecophysiology of coral reef primary producers across an upwelling gradient in the tropical central Pacific

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    © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Johnson, M. D., Fox, M. D., Kelly, E. L. A., Zgliczynski, B. J., Sandin, S. A., & Smith, J. E. Ecophysiology of coral reef primary producers across an upwelling gradient in the tropical central Pacific. Plos One, 15(2), (2020): e0228448, doi:10.1371/journal.pone.0228448.Upwelling is an important source of inorganic nutrients in marine systems, yet little is known about how gradients in upwelling affect primary producers on coral reefs. The Southern Line Islands span a natural gradient of inorganic nutrient concentrations across the equatorial upwelling region in the central Pacific. We used this gradient to test the hypothesis that benthic autotroph ecophysiology is enhanced on nutrient-enriched reefs. We measured metabolism and photophysiology of common benthic taxa, including the algae Porolithon, Avrainvillea, and Halimeda, and the corals Pocillopora and Montipora. We found that temperature (27.2–28.7°C) was inversely related to dissolved inorganic nitrogen (0.46–4.63 μM) and surface chlorophyll a concentrations (0.108–0.147 mg m-3), which increased near the equator. Contrary to our prediction, ecophysiology did not consistently track these patterns in all taxa. Though metabolic rates were generally variable, Porolithon and Avrainvillea photosynthesis was highest at the most productive and equatorial island (northernmost). Porolithon photosynthetic rates also generally increased with proximity to the equator. Photophysiology (maximum quantum yield) increased near the equator and was highest at northern islands in all taxa. Photosynthetic pigments also were variable, but chlorophyll a and carotenoids in Avrainvillea and Montipora were highest at the northern islands. Phycobilin pigments of Porolithon responded most consistently across the upwelling gradient, with higher phycoerythrin concentrations closer to the equator. Our findings demonstrate that the effects of in situ nutrient enrichment on benthic autotrophs may be more complex than laboratory experiments indicate. While upwelling is an important feature in some reef ecosystems, ancillary factors may regulate the associated consequences of nutrient enrichment on benthic reef organisms.This work was supported by funding from the Moore Family Foundation, the Gordon and Betty Moore Foundation, the Scripps family, and anonymous donors. The funders had no role in study design, data collection and analysis, or preparation of the manuscript

    The development, feasibility and acceptability of a school-based obesity prevention programme: results from three phases of piloting

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    addresses: Institute for Health Service Research, Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, UK.notes: PMCID: PMC3191390types: Journal Article; Research Support, Non-U.S. Gov'tCopyright © 2011 by the BMJ Publishing Group Ltd. This articles was first published in: BMJ, 2011, Vol. 1, Issue 1, pp. e000026 -To develop a school-based obesity prevention programme and evaluate the feasibility and acceptability of the intervention and the planned definitive cluster randomised trial

    Analysis of recurrent events with an associated informative dropout time: Application of the joint frailty model.

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    This paper considers the analysis of a repeat event outcome in clinical trials of chronic diseases in the context of dependent censoring (e.g. mortality). It has particular application in the context of recurrent heart failure hospitalisations in trials of heart failure. Semi-parametric joint frailty models (JFMs) simultaneously analyse recurrent heart failure hospitalisations and time to cardiovascular death, estimating distinct hazard ratios whilst individual-specific latent variables induce associations between the two processes. A simulation study was carried out to assess the suitability of the JFM versus marginal analyses of recurrent events and cardiovascular death using standard methods. Hazard ratios were consistently overestimated when marginal models were used, whilst the JFM produced good, well-estimated results. An application to the Candesartan in Heart failure: Assessment of Reduction in Mortality and morbidity programme was considered. The JFM gave unbiased estimates of treatment effects in the presence of dependent censoring. We advocate the use of the JFM for future trials that consider recurrent events as the primary outcome. © 2016 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd

    Influence of Maternal Glycemia on Intrauterine Fetal Adiposity Distribution after a Normal Oral Glucose Tolerance Test at 28 Weeks Gestation

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    Objective. To examine the relationship between maternal glucose levels and intrauterine fetal adiposity distribution in women with a normal oral glucose tolerance test (OGTT) at 28 weeks gestation. Study Design. We recruited 231 women with a singleton pregnancy. At 28 and 37 weeks gestation, sonographic measurements of fetal body composition were performed. Multiple regression analysis was used to study the influence of different maternal variables on fetal adiposity distribution. Results. Maternal glucose levels correlated with the fetal abdominal subcutaneous tissue measurements (r = 0.2; P = 0.014) and with birth weight (r = 0.1; P = 0.04). Maternal glucose levels did not correlate with the fetal mid-thigh muscle thickness and mid-thigh subcutaneous tissue measurements. Conclusion. We found that in nondiabetic women maternal glucose levels not only influence fetal adiposity and birth weight, but also influence the distribution of fetal adiposity. This supports previous evidence that maternal glycemia is a key determinant of intrauterine fetal programming

    Infection control and the significance of sputum and other respiratory secretions from adult patients with cystic fibrosis

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    BACKGROUND: There is limited data available on the environmental and public health impact of the microbiological hazards associated with sputa from patients with cystic fibrosis [CF]. Pseudomonas aeruginosa, Burkholderia cenocepacia (formerly Burkholderia cepacia genomovar III), Staphylococcus aureus and Stenotrophomonas maltophilia are bacterial pathogens which are commonly found in the sputum of CF patients. A study was performed to ascertain the amount of sputum produced relating to microbial loading, as well as the diversity of bacteria present in a population of adult patients, with particular attention to pathogenic organisms. METHODS: Sputum from adult [>18 years old] CF patients [n = 20], chosen randomly from a population of 138 CF patients, was collected over a 24 h period on admission to the in-patient CF unit and enumerated quantitatively, as well as the sputa from 138 adult CF patients was examined qualitatively for the presence of infecting microflora. In addition, all different phenotypes from the sputum of each patient were identified phenotypically employing a combination of conventional identification methods [e.g. oxidase], as well as the API Identification schemes [API 20 NE, API 20 E]. RESULTS: This study demonstrated that patients with cystic fibrosis generate large numbers of bacteria in their sputum, approximating to 10(9 )organisms per patient per day. Although these organisms are introduced to the environment from the respiratory tract mainly via sputum, relatively few represent true bacterial pathogens and therefore are not clinically important to the general public who are immunocompotent. The greatest risk of such environmental microbial loading is to other patients with CF and therefore CF patients should be made aware of the hazards of acquiring such organisms from the environment, as well as socializing with other CF patients with certain transmissible types, such as Pseudomonas aeruginosa and Burkholderia cenocepacia. CONCLUSIONS: Environmental health professionals should therefore be aware that CF patients are a greater risk to their peer grouping rather than to the general public or health care workers and that good personal hygiene practices with CF patients should be encouraged to minimize environmental contamination and potential acquistion

    Benthic communities at two remote Pacific coral reefs: effects of reef habitat, depth, and wave energy gradients on spatial patterns

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    Kingman Reef and Palmyra Atoll in the central Pacific are among the most remote coral reefs on the planet. Here we describe spatial patterns in their benthic communities across reef habitats and depths, and consider these in the context of oceanographic gradients. Benthic communities at both locations were dominated by calcifying organisms (54–86% cover), namely hard corals (20–74%) and crustose coralline algae (CCA) (10–36%). While turf algae were relatively common at both locations (8–22%), larger fleshy macroalgae were virtually absent at Kingman (<1%) and rare at Palmyra (0.7–9.3%). Hard coral cover was higher, but with low diversity, in more sheltered habitats such as Palmyra’s backreef and Kingman’s patch reefs. Almost exclusive dominance by slow-growing Porites on Kingman’s patch reefs provides indirect evidence of competitive exclusion, probably late in a successional sequence. In contrast, the more exposed forereef habitats at both Kingman and Palmyra had higher coral diversity and were characterized by fast-growing corals (e.g., Acropora and Pocillopora), indicative of more dynamic environments. In general at both locations, soft coral cover increased with depth, likely reflecting increasingly efficient heterotrophic abilities. CCA and fleshy macroalgae cover decreased with depth, likely due to reduced light. Cover of other calcified macroalgae, predominantly Halimeda, increased with depth. This likely reflects the ability of many calcifying macroalgae to efficiently harvest light at deeper depths, in combination with an increased nutrient supply from upwelling promoting growth. At Palmyra, patterns of hard coral cover with depth were inconsistent, but cover peaked at mid-depths at Kingman. On Kingman’s forereef, benthic community composition was strongly related to wave energy, with hard coral cover decreasing and becoming more spatially clustered with increased wave energy, likely as a result of physical damage leading to patches of coral in localized shelter. In contrast, the cover of turf algae at Kingman was positively related to wave energy, reflecting their ability to rapidly colonize newly available space. No significant patterns with wave energy were observed on Palmyra’s forereef, suggesting that a more detailed model is required to study biophysical coupling there. Kingman, Palmyra, and other remote oceanic reefs provide interesting case studies to explore biophysical influences on benthic ecology and dynamics

    Quantitative Genetic Mapping and Genome Assembly in the Lesser Wax Moth Achroia grisella

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    This work is licensed under a Creative Commons Attribution 4.0 International License.Specific characteristics of the male Achroia grisella acoustic mating signal determine a male’s attractiveness toward females. These features are genetically variable in populations, and mapping experiments have been used to identify loci contributing to song variation, and understand the evolutionary forces acting on this important sexual trait. Here we built on this foundation and carried out QTL (Quantitative Trait Locus) mapping using >1,000 recombinant individuals, genotyping this large cohort at thousands of sequence-based markers covering the entire collection of 30 A. grisella chromosomes. This dense marker set, coupled with our development of an annotated, draft genome of A. grisella, allowed us to link >3,000 genome scaffolds, >10,000 predicted genes, and close to 275Mb of genome sequence to chromosomes. Our QTL mapping confirmed a fraction of the QTL identified in a previous study, and additionally revealed novel loci. Collectively, QTL explained only small fractions of the phenotypic variance, suggesting many more causative factors remain below the detection threshold of our study. A surprising, and ultimately challenging feature of our study was the low level of intrachromosomal recombination present in our mapping population. This led to difficulty ordering markers along linkage groups, necessitating a chromosome-by-chromosome mapping approach, rather than true interval mapping, and precluded confident ordering/orienting of scaffolds along each chromosome. Nonetheless, our study increased the genomic resources available for the A. grisella system. Enabled by ever more powerful technologies, future investigators will be able to leverage our data to provide more detailed genetic dissection of male song variation in A. grisella.NSF IOB-0516634NIGMS award P20GM103638NIGMS award P20GM103418NIH R01 GM085260NIH R01 OD01097
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