1,061 research outputs found

    Sex Differences in Vascular Compliance in Normal-Weight but Not Obese Boys and Girls: The Effect of Body Composition

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    Objectives. To determine the effect of sex and obesity on vascular function in children and explore potential mechanisms that account for differences in vascular function. Methods. Participants were 61 (30 boys) normal-weight (BMI 25–75% ile for age and sex) and 62 (30 boys) obese (BMI ≥ 95% ile) children of ages 8–18 years. Measurements of large and small artery elastic index (LAEI and SAEI, resp.) and reactive hyperemia index (RHI) were obtained at rest, along with anthropometric and biochemical information. Results. In normal-weight children, LAEI was 16% higher in males than females (P = 0.04) with a similar trend for SAEI (13% higher in males, P = 0.067). In obese children, no sex-related differences in vascular measures were observed. In multivariable models, sex differences in arterial compliance were explained by higher lean mass in normal-weight boys. Fat mass predicted LAEI and SAEI in both normal-weight and obese females, but fat mass predicted arterial compliance in boys when fat mass exceeded 24 kg (37% of the sample). Conclusions. Normal-weight males have higher arterial compliance than normal-weight females due to increased lean mass, but sex-related differences were not observed among obese children due to a lack of sex-related differences in lean or fat mass

    What's the Matter with Kansas?: The Development and Confirmation of the Evolutionary Attitudes and Literacy Survey (EALS)

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    This is the publisher's version, also available electronically from http://link.springer.com/article/10.1007%2Fs12052-010-0294-1.The present survey was designed to assess predominant regional belief systems and the roles these beliefs play in science understanding and attitudes, and curricular effectiveness in colleges and universities. To this end, we created a wide variety of theory-driven subscales (lower order factors) reflecting, for example, exposure to evolutionary material, young earth creationist beliefs, moral and social objections, political ideology, endorsement of intelligent design fallacies, knowledge (and distrust) of the scientific enterprise, and attitudes of evolutionary theory’s relevance in several domains (e.g., sciences and humanities). We also included potentially important demographic variables (e.g., rural upbringing, family size). Finally, we assessed openness to experience, a key facet of personality. Hierarchical Structural Equation Modeling (SEM) analysis showed the 16 constructs to have a theoretically meaningful and quantitatively coherent higher order factor structure. In this large Kansas sample of university students, creationist reasoning and conservative orientation (political and religious) were negatively associated with exposure to evolutionary theory, knowledge about it, and positive attitudes toward its relevance. At the same time, exposure to the theory was positively associated with knowledge and positive attitudes. Importantly, though most Kansas-specific demographic variables (e.g., rural origins) were largely unrelated to outcomes of interest in this university-based sample, the personality factor openness to experience appears to be highly relevant for several higher order factors (e.g., exposure, knowledge and relevance, and creationist reasoning). We close with implications for educators and the next steps in survey development

    What's the Matter with Kansas?: The Development and Confirmation of the Evolutionary Attitudes and Literacy Survey (EALS)

    Get PDF
    This is the publisher's version, also available electronically from http://link.springer.com/article/10.1007%2Fs12052-010-0294-1.The present survey was designed to assess predominant regional belief systems and the roles these beliefs play in science understanding and attitudes, and curricular effectiveness in colleges and universities. To this end, we created a wide variety of theory-driven subscales (lower order factors) reflecting, for example, exposure to evolutionary material, young earth creationist beliefs, moral and social objections, political ideology, endorsement of intelligent design fallacies, knowledge (and distrust) of the scientific enterprise, and attitudes of evolutionary theory’s relevance in several domains (e.g., sciences and humanities). We also included potentially important demographic variables (e.g., rural upbringing, family size). Finally, we assessed openness to experience, a key facet of personality. Hierarchical Structural Equation Modeling (SEM) analysis showed the 16 constructs to have a theoretically meaningful and quantitatively coherent higher order factor structure. In this large Kansas sample of university students, creationist reasoning and conservative orientation (political and religious) were negatively associated with exposure to evolutionary theory, knowledge about it, and positive attitudes toward its relevance. At the same time, exposure to the theory was positively associated with knowledge and positive attitudes. Importantly, though most Kansas-specific demographic variables (e.g., rural origins) were largely unrelated to outcomes of interest in this university-based sample, the personality factor openness to experience appears to be highly relevant for several higher order factors (e.g., exposure, knowledge and relevance, and creationist reasoning). We close with implications for educators and the next steps in survey development

    Filling some black holes: modeling the connection between urbanization, infrastructure, and global service intensity

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    This empirical article combines insights from previous research on the level of knowledge-intensive service in metropolitan areas with the aim to develop an understanding of the spatial structure of the global service economy. We use a stepwise regression model with the Globalization and World Cities research network's measure of globalized service provisioning as the dependent variable and a range of variables focusing on population, infrastructure, urban primacy, and national regulation as independent variables. The discussion of the results focuses on model parameters as well as the meaning of outliers and is used to explore some avenues for future research

    Kinetics of the Xanthophyll Cycle and its Role in the Photoprotective Memory and Response

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    Efficiently balancing photochemistry and photoprotection is crucial for survival and productivity of photosynthetic organisms in the rapidly fluctuating light levels found in natural environments. The ability to respond quickly to sudden changes in light level is clearly advantageous. In the alga Nannochloropsis oceanica we observed an ability to respond rapidly to sudden increases in light level which occur soon after a previous high-light exposure. This ability implies a kind of memory. In this work, we explore the xanthophyll cycle in N. oceanica as a photoprotective memory system. By combining snapshot fluorescence lifetime measurements with a biochemistry-based quantitative model we show that both short-term and medium-term "memory" arises from the xanthophyll cycle. In addition, the model enables us to characterize the relative quenching abilities of the three xanthophyll cycle components. Given the ubiquity of the xanthophyll cycle in photosynthetic organisms the model described here will be of utility in improving our understanding of vascular plant photoprotection with important implications for crop productivity

    Self-similar scaling and evolution in the galaxy cluster X-ray Luminosity-Temperature relation

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    We investigate the form and evolution of the X-ray luminosity-temperature (LT) relation of a sample of 114 galaxy clusters observed with Chandra at 0.1<z<1.3. The clusters were divided into subsamples based on their X-ray morphology or whether they host strong cool cores. We find that when the core regions are excluded, the most relaxed clusters (or those with the strongest cool cores) follow an LT relation with a slope that agrees well with simple self-similar expectations. This is supported by an analysis of the gas density profiles of the systems, which shows self-similar behaviour of the gas profiles of the relaxed clusters outside the core regions. By comparing our data with clusters in the REXCESS sample, which extends to lower masses, we find evidence that the self-similar behaviour of even the most relaxed clusters breaks at around 3.5keV. By contrast, the LT slopes of the subsamples of unrelaxed systems (or those without strong cool cores) are significantly steeper than the self-similar model, with lower mass systems appearing less luminous and higher mass systems appearing more luminous than the self-similar relation. We argue that these results are consistent with a model of non-gravitational energy input in clusters that combines central heating with entropy enhancements from merger shocks. Such enhancements could extend the impact of central energy input to larger radii in unrelaxed clusters, as suggested by our data. We also examine the evolution of the LT relation, and find that while the data appear inconsistent with simple self-similar evolution, the differences can be plausibly explained by selection bias, and thus we find no reason to rule out self-similar evolution. We show that the fraction of cool core clusters in our (non-representative) sample decreases at z>0.5 and discuss the effect of this on measurements of the evolution in the LT relation.Comment: 21 pages, 15 figures. Submitted to MNRAS. Comments welcom

    Physics-based multiscale coupling for full core nuclear reactor simulation

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    Numerical simulation of nuclear reactors is a key technology in the quest for improvements in efficiency, safety, and reliability of both existing and future reactor designs. Historically, simulation of an entire reactor was accomplished by linking together multiple existing codes that each simulated a subset of the relevant multiphysics phenomena. Recent advances in the MOOSE (Multiphysics Object Oriented Simulation Environment) framework have enabled a new approach: multiple domain-specific applications, all built on the same software framework, are efficiently linked to create a cohesive application. This is accomplished with a flexible coupling capability that allows for a variety of different data exchanges to occur simultaneously on high performance parallel computational hardware. Examples based on the KAIST-3A benchmark core, as well as a simplified Westinghouse AP-1000 configuration, demonstrate the power of this new framework for tackling—in a coupled, multiscale manner—crucial reactor phenomena such as CRUD-induced power shift and fuel shuffle.Massachusetts Institute of Technology. Department of Nuclear Science and EngineeringIdaho National Laboratory (Contract DE-AC07-05ID14517

    The clinical impact of Lumacaftor-Ivacaftor on structural lung disease and lung function in children aged 6-11 with cystic fibrosis in a real-world setting

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    BACKGROUND: Data from clinical trials of lumacaftor-ivacaftor (LUM-IVA) demonstrate improvements in lung clearance index (LCI) but not in FEV1 in children with Cystic Fibrosis (CF) aged 6-11 years and homozygous for the Phe508del mutation. It is not known whether LUM/IVA use in children can impact the progression of structural lung disease. We sought to determine the real-world impact of LUM/IVA on lung structure and function in children aged 6-11 years. METHODS: This real-world observational cohort study was conducted across four paediatric sites in Ireland over 24-months using spirometry-controlled CT scores and LCI as primary outcome measures. Children commencing LUM-/IVA as part of routine care were included. CT scans were manually scored with the PRAGMA CF scoring system and analysed using the automated bronchus-artery (BA) method. Secondary outcome measures included rate of change of ppFEV1, nutritional indices and exacerbations requiring hospitalisation. RESULTS: Seventy-one participants were recruited to the study, 31 of whom had spirometry-controlled CT performed at baseline, and after one year and two years of LUM/IVA treatment. At two years there was a reduction from baseline in trapped air scores (0.13 to 0.07, p = 0.016), but an increase from baseline in the % bronchiectasis score (0.84 to 1.23, p = 0.007). There was no change in overall % disease score (2.78 to 2.25, p = 0.138). Airway lumen to pulmonary artery ratios (AlumenA ratio) were abnormal at baseline and worsened over the course of the study. In 28 participants, the mean annual change from baseline LCI2.5 (-0.055 (-0.61 to 0.50), p = 0.85) measurements over two years were not significant. Improvements from baseline in weight (0.10 (0.06 to 0.15, p < 0.0001), height (0.05 (0.02 to 0.09), p = 0.002) and BMI (0.09 (0.03 to 0.15) p = 0.005) z-scores were seen with LUM/IVA treatment. The mean annual change from baseline ppFEV1 (-2.45 (-4.44 to 2.54), p = 0.66) measurements over two years were not significant. CONCLUSION: In a real-world setting, the use of LUM/IVA over two years in children with CF aged 6-11 resulted in improvements in air trapping on CT but worsening in bronchiectasis scores. Our results suggest that LUM/IVA use in this age group improves air trapping but does not prevent progression of bronchiectasis over two years of treatment
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