3,773 research outputs found

    Ising Field Theory on a Pseudosphere

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    We show how the symmetries of the Ising field theory on a pseudosphere can be exploited to derive the form factors of the spin fields as well as the non-linear differential equations satisfied by the corresponding two-point correlation functions. The latter are studied in detail and, in particular, we present a solution to the so-called connection problem relating two of the singular points of the associated Painleve VI equation. A brief discussion of the thermodynamic properties is also presented.Comment: 39 pages, 6 eps figures, uses harvma

    Multiscale correlative characterization of environmentally assisted crack initiation, propagation and failure in a high strength AA5083 H131 alloy

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    Environmentally assisted cracking in a high strength AA5083 H131 alloy has been investigated using a multiscale correlative characterization approach to understand the surface intergranular corrosion to environmentally assisted crack (EAC) transition. Time-lapse 3D synchrotron X-ray tomography was employed during slow strain testing of a sensitized AA5083 sample sensitized at 80 °C for 250 h. In addition, several of the specimens tested were pre-exposed to a chloride containing environment to induce corrosion sites which could act as ‘realistic’ stress raisers in the subsequent straining. Reconstructed volumes of the X-ray CT time-lapse series allowed us to track and follow crack propagation in the material during slow strain rate testing at high resolution \u3c5 µm. Volumes of interest from the test samples identified from the X-ray CT reconstructions were further analyzed post-mortem using electron microscopy and spectroscopy based techniques to study the presence and chemistry of secondary phases such as those based on Mg-Si, and their role in the initiation, propagation and/or arrest of crack tips/fronts

    Genetic and pharmacological relationship between P-Glycoprotein and increased cardiovascular risk associated with clarithromycin prescription:An Epidemiological and Genomic Population-Based Cohort Study in Scotland, UK

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    BackgroundThere are conflicting reports regarding the association of the macrolide antibiotic clarithromycin with cardiovascular (CV) events. A possible explanation may be that this risk is partly mediated through drug-drug interactions and only evident in at-risk populations. To the best of our knowledge, no studies have examined whether this association might be mediated via P-glycoprotein (P-gp), a major pathway for clarithromycin metabolism. The aim of this study was to examine CV risk following prescription of clarithromycin versus amoxicillin and in particular, the association with P-gp, a major pathway for clarithromycin metabolism.Methods and findingsWe conducted an observational cohort study of patients prescribed clarithromycin or amoxicillin in the community in Tayside, Scotland (population approximately 400,000) between 1 January 2004 and 31 December 2014 and a genomic observational cohort study evaluating genotyped patients from the Genetics of Diabetes Audit and Research Tayside Scotland (GoDARTS) study, a longitudinal cohort study of 18,306 individuals with and without type 2 diabetes recruited between 1 December 1988 and 31 December 2015. Two single-nucleotide polymorphisms associated with P-gp activity were evaluated (rs1045642 and rs1128503 -AA genotype associated with lowest P-gp activity). The primary outcome for both analyses was CV hospitalization following prescription of clarithromycin versus amoxicillin at 0-14 days, 15-30 days, and 30 days to 1 year. In the observational cohort study, we calculated hazard ratios (HRs) adjusted for likelihood of receiving clarithromycin using inverse proportion of treatment weighting as a covariate, whereas in the pharmacogenomic study, HRs were adjusted for age, sex, history of myocardial infarction, and history of chronic obstructive pulmonary disease. The observational cohort study included 48,026 individuals with 205,227 discrete antibiotic prescribing episodes (34,074 clarithromycin, mean age 73 years, 42% male; 171,153 amoxicillin, mean age 74 years, 45% male). Clarithromycin use was significantly associated with increased risk of CV hospitalization compared with amoxicillin at both 0-14 days (HR 1.31; 95% CI 1.17-1.46, p ConclusionsIn this study, we observed that the increased risk of CV events with clarithromycin compared with amoxicillin was associated with an interaction with P-glycoprotein

    Trajectories of Inflammation in Youth and Risk of Mental and Cardiometabolic Disorders in Adulthood

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    IMPORTANCE: Research suggests that low-grade, nonresolving inflammation may predate adult mental and physical illness. However, evidence to date is largely cross-sectional or focuses on single disorder outcomes.OBJECTIVES: To examine trajectories of inflammation as measured by C-reactive protein (CRP) levels in a large sample of children and adolescents, and to explore associations between different identified trajectories and mental and related cardiometabolic health outcomes in early adulthood.DESIGN, SETTING, AND PARTICIPANTS: In a longitudinal cohort study using data from the large UK-based Avon Longitudinal Study of Parents and Children (ALSPAC), latent class growth analysis (LCGA) was used to explore different trajectories of inflammation, with logistic regression exploring association with mental and physical health outcomes. Participants with measurable CRP data and associated mental and cardiometabolic health outcomes recorded were included in the analysis. Data analysis was performed from May 1, 2023, to March 30, 2024.EXPOSURES: Inflammation was assessed via CRP levels at ages 9, 15, and 17 years. LCGA was used to identify different trajectories of inflammation.MAIN OUTCOMES AND MEASURES: Outcomes assessed at age 24 years included psychotic disorders, depressive disorders, anxiety disorders, hypomania, and, as a measure of insulin resistance, Homeostasis Model Assessment (HOMA2) score.RESULTS: A total of 6556 participants (3303 [50.4%] female) were included. Three classes of inflammation were identified: persistently low CRP levels (reference class, n = 6109); persistently raised CRP levels, peaking at age 9 years (early peak, n = 197); and persistently raised CRP levels, peaking at age 17 years (late peak, n = 250). Participants in the early peak group were associated with a higher risk of psychotic disorder (odds ratio [OR], 4.60; 95% CI, 1.81-11.70; P = .008), a higher risk of severe depression (OR, 4.37; 95% CI, 1.64-11.63; P = .02), and higher HOMA2 scores (β = 0.05; 95% CI, 0.01-0.62, P = .04) compared with participants with persistently low CRP. The late peak group was not associated with any outcomes at age 24 years.CONCLUSIONS AND RELEVANCE: Low-grade systemic inflammation peaking in midchildhood was associated with specific mental and cardiometabolic disorders in young adulthood. These findings suggest that low-grade persistent inflammation in early life may be an important shared common factor for mental-physical comorbidity and so could be relevant to future efforts of patient stratification and risk profiling.</p

    Costs of school transportation: quantifying the fiscal impacts of encouraging walking and bicycling for school travel

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    Abstract National governments have provided subsidies for investments in increasing the safety and attractiveness of walking and biking to school. Evaluations of Safe Routes to School initiatives have found that they have been effective at changing behavior and reducing injuries. However, there has been little attention to the impacts of these programs on pupil transportation costs. This analysis assesses the potential economic benefits of Safe Routes to School programs in the US context by estimating the annual costs of using motorized transport for short trips to schools, examining real-world examples of the costs savings of SRTS programs, and evaluating land use impacts on school transportation costs using a simulation analysis of school bus routes. We find that there is potential for school districts and families to reduce transport expenditures through public sector investments in walking and biking infrastructure near schools. We also find that land use context matters and the most cost-effective investments would benefit schools where large numbers of children live within walking distance

    Associations among Adolescent Sleep Problems, Emotion Regulation, and Affective Disorders: Findings from a Nationally Representative Sample.

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    The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Sleep problems in youth reliably forecast the development of anxiety and mood disorders, presumably due to increased emotional difficulties. However, precise emotional mechanisms have yet to be delineated. The current study investigated how sleep problems in adolescence are associated with different emotion regulation strategies, and how sleep and psychiatric risk may be indirectly associated via poor emotion regulation. This study utilized data from the National Comorbidity Survey-Adolescent Supplement, a nationally representative sample from the United States (N = 10,148; age range 13–18 years). A diagnostic interview determined if adolescents qualified for a mood or anxiety disorder within the past year. Participants provided reports of their sleep, emotion regulation, and current life stress. Adolescents who reported greater sleep problems were more likely to qualify for a mood or anxiety disorder and generally reported poorer emotion regulation strategy use, even when accounting for demographic characteristics and current stress. Specifically, adolescents with greater sleep problems reported less problem solving, and greater avoidance, suppression, rumination, and acceptance. Sleep problems were indirectly associated with anxiety disorders through greater suppression and rumination, and indirectly associated with mood disorders through greater rumination and lower problem solving. Although cross-sectional, this study extends current research by suggesting that certain emotion regulation strategies may be more difficult for youth struggling with sleep problems, and provides initial evidence that poor emotion regulation may be one factor contributing to sleep-based psychiatric risk. These findings can inform more efficacious intervention efforts

    Resolved Near-infrared Stellar Populations in Nearby Galaxies

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    We present near-infrared (NIR) color-magnitude diagrams (CMDs) for the resolved stellar populations within 26 fields of 23 nearby galaxies (≲ 4 Mpc), based on images in the F110W and F160W filters taken with the Wide-Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). The CMDs are measured in regions spanning a wide range of star formation histories, including both old dormant and young star-forming populations. We match key NIR CMD features with their counterparts in more familiar optical CMDs, and identify the red core helium-burning (RHeB) sequence as a significant contributor to the NIR flux in stellar populations younger than a few 100 Myr old. The strength of this feature suggests that the NIR mass-to-light ratio can vary significantly on short timescales in star-forming systems. The NIR luminosity of star-forming galaxies is therefore not necessarily proportional to the stellar mass. We note that these individual RHeB stars may also be misidentified as old stellar clusters in images of nearby galaxies. For older stellar populations, we discuss the CMD location of asymptotic giant branch (AGB) stars in the HST filter set and explore the separation of AGB subpopulations using a combination of optical and NIR colors. We empirically calibrate the magnitude of the NIR tip of the red giant branch in F160W as a function of color, allowing future observations in this widely adopted filter set to be used for distance measurements. We also analyze the properties of the NIR red giant branch (RGB) as a function of metallicity, showing a clear trend between NIR RGB color and metallicity. However, based on the current study, it appears unlikely that the slope of the NIR RGB can be used as an effective metallicity indicator in extragalactic systems with comparable data. Finally, we highlight issues with scattered light in the WFC3, which becomes significant for exposures taken close to a bright Earth limb

    Reducing persecution is more effective for restoring large carnivores than restoring their prey

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    We gratefully acknowledge funding by the Federal State of Berlin, Germany (Elsa Neumann Scholarship to BB), and the German Research Foundation (GH 149/1-1 and ZU 361/1-1). We further thank all participants of the workshop on the revi- sion of the Strategy for Leopard Conservation in the Caucasus in Tbilisi, Georgia in 2017. We are grateful to J. Buchner, A. Heidelberg, V.C. Radeloff, and H. Yin for fruitful discussions, and F. Poetzschner for help with preparing data. Additionally, we thank two anonymous reviewers for their constructive comments.Peer reviewedPublisher PD

    The ACS Nearby Galaxy Survey Treasury IV. The Star Formation History of NGC 2976

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    We present resolved stellar photometry of NGC 2976 obtained with the Advanced Camera for Surveys (ACS) as part of the ACS Nearby Galaxy Survey Treasury (ANGST) program. The data cover the radial extent of the major axis of the disk out to 6 kpc, or ~6 scale lengths. The outer disk was imaged to a depth of M_F606W ~ 1, and an inner field was imaged to the crowding limit at a depth of M_F606W ~ -1. Through detailed analysis and modeling of these CMDs we have reconstructed the star formation history of the stellar populations currently residing in these portions of the galaxy, finding similar ancient populations at all radii but significantly different young populations at increasing radii. In particular, outside of the well-measured break in the disk surface brightness profile, the age of the youngest population increases with distance from the galaxy center, suggesting that star formation is shutting down from the outside-in. We use our measured star formation history, along with H I surface density measurements, to reconstruct the surface density profile of the disk during previous epochs. Comparisons between the recovered star formation rates and reconstructed gas densities at previous epochs are consistent with star formation following the Schmidt law during the past 0.5 Gyrs, but with a drop in star formation efficiency at low gas densities, as seen in local galaxies at the present day. The current rate and gas density suggest that rapid star formation in NGC 2976 is currently in the process of ceasing from the outside-in due to gas depletion. This process of outer disk gas depletion and inner disk star formation was likely triggered by an interaction with the core of the M81 group >~1 Gyr ago that stripped the gas from the galaxy halo and/or triggered gas inflow from the outer disk toward the galaxy center.Comment: 22 pages, 14 figures, 2 tables, accepted for publication by Ap
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