228 research outputs found

    Taking stock of arctic sea ice and climate

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    Abstract The relationship among the cause-and-effect of the Arctic atmosphere, sea ice, and ocean is discussed. The increased vulnerability of the Arctic system to anomalous atmospheric forcing can be argued from the perspective that recent ice loss is the result of a long-term preconditioning to thinner ice. Such consequences demonstrate the difficulties inherent in ascertaining how the atmospheric circulation responds to Arctic, and global, climate change. Later-forming sea ice also leads to less protection from the waves of fall storms, affecting coastal communities such as Kivalina and Shishmaref. The coming decades will provide new insights into the complexities of the Arctic climate system and how changes will affect the biological and human communities within and beyond its boundaries

    Ara h 6 Complements Ara h 2 as an Important Marker for IgE Reactivity to Peanut

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    The similarities of two major peanut allergens, Ara h 2 and Ara h 6, in molecular size, amino acid sequence, and structure have made it difficult to obtain natural Ara h 6 free of Ara h 2. The objectives of this study were to purify natural Ara h 6 that is essentially free of Ara h 2 and to compare its IgE reactivity and potency in histamine release assays to Ara h 2. SDS-PAGE of the highly purified allergen (\u3c0.01% Ara h 2) revealed a single 14.5kD band and the identity of Ara h 6 was confirmed by LC-MS/MS. Ara h 6 showed a higher seroprevalence in chimeric-IgE ELISA (n=54), but a weaker biological activity in basophil histamine release assays than Ara h 2. Purified Ara h 6 will be useful for diagnostic IgE antibody assays, as well as molecular and cellular studies to investigate the immunological mechanisms of peanut allergy

    Ara h 6 Complements Ara h 2 as an Important Marker for IgE Reactivity to Peanut

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    The similarities of two major peanut allergens, Ara h 2 and Ara h 6, in molecular size, amino acid sequence, and structure have made it difficult to obtain natural Ara h 6 free of Ara h 2. The objectives of this study were to purify natural Ara h 6 that is essentially free of Ara h 2 and to compare its IgE reactivity and potency in histamine release assays to Ara h 2. SDS-PAGE of the highly purified allergen (\u3c0.01% Ara h 2) revealed a single 14.5kD band and the identity of Ara h 6 was confirmed by LC-MS/MS. Ara h 6 showed a higher seroprevalence in chimeric-IgE ELISA (n=54), but a weaker biological activity in basophil histamine release assays than Ara h 2. Purified Ara h 6 will be useful for diagnostic IgE antibody assays, as well as molecular and cellular studies to investigate the immunological mechanisms of peanut allergy

    The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: Analysis of potential systematics

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    We analyze the density field of galaxies observed by the Sloan Digital Sky Survey (SDSS)-III Baryon Oscillation Spectroscopic Survey (BOSS) included in the SDSS Data Release Nine (DR9). DR9 includes spectroscopic redshifts for over 400,000 galaxies spread over a footprint of 3,275 deg^2. We identify, characterize, and mitigate the impact of sources of systematic uncertainty on large-scale clustering measurements, both for angular moments of the redshift-space correlation function and the spherically averaged power spectrum, P(k), in order to ensure that robust cosmological constraints will be obtained from these data. A correlation between the projected density of stars and the higher redshift (0.43 < z < 0.7) galaxy sample (the `CMASS' sample) due to imaging systematics imparts a systematic error that is larger than the statistical error of the clustering measurements at scales s > 120h^-1Mpc or k < 0.01hMpc^-1. We find that these errors can be ameliorated by weighting galaxies based on their surface brightness and the local stellar density. We use mock galaxy catalogs that simulate the CMASS selection function to determine that randomly selecting galaxy redshifts in order to simulate the radial selection function of a random sample imparts the least systematic error on correlation function measurements and that this systematic error is negligible for the spherically averaged correlation function. The methods we recommend for the calculation of clustering measurements using the CMASS sample are adopted in companion papers that locate the position of the baryon acoustic oscillation feature (Anderson et al. 2012), constrain cosmological models using the full shape of the correlation function (Sanchez et al. 2012), and measure the rate of structure growth (Reid et al. 2012). (abridged)Comment: Matches version accepted by MNRAS. Clarifications and references have been added. See companion papers that share the "The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey:" titl

    Harms reporting in systematic reviews of microvascular free flap in head and neck reconstruction

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    Objective: To evaluate harms reporting in systematic reviews of microvascular free flap in head and neck reconstruction.Data Sources: This cross-sectional analysis included searches from the following major databases from 2012 to June 1, 2022: MEDLINE (Pubmed and Ovid), Embase, Epistemonikos, and the Cochrane Database of Systematic Reviews.Review Methods: In a masked duplicate manner, screening was performed using Rayyan, and data was extracted using a pilot-tested Google form. AMSTAR-2 was used to appraise the methodological quality of reviews, and Corrected Covered Area was calculated to detect primary study overlap across all reviews. Reviews were then grouped in pairs of two, called dyads, and Corrected Covered Area was calculated again for each individual dyad. Dyads with high overlap (≥50%) were further investigated for accuracy of harms reporting.Results: Our initial search yielded 268 records, with 50 systematic reviews meeting inclusion criteria. A total of 46 (92%) of the included reviews demonstrated 50% or more adherence to the items assessed in our harms checklist. Our Corrected Covered Area tool revealed 0.6% primary study overlap across all reviews, and one dyad with high overlap (≥ 50%). No statistically significant relationship was observed between the completeness of harms reporting and reviews listing harms as a primary outcome, reviews reporting adherence to PRISMA, or a review’s AMSTAR rating.Conclusion: This study identifies how harms reporting in systematic reviews of microvascular free flap reconstruction of the head and neck can be improved and provides suggestions with potential to mitigate the paucity in current literature

    A Cox-Aalen model for interval-censored data

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    This is the peer reviewed version of the following article: Boruvka, A., and Cook, R. J. (2015), A Cox-Aalen Model for Interval-censored Data. Scand J Statist, 42, 414–426. doi: 10.1111/sjos.12113., which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1111/sjos.12113/full. This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.The Cox-Aalen model, obtained by replacing the baseline hazard function in the well-known Cox model with a covariate-dependent Aalen model, allows for both fixed and dynamic covariate effects. In this paper, we examine maximum likelihood estimation for a Cox-Aalen model based on interval-censored failure times with fixed covariates. The resulting estimator globally converges to the truth slower than the parametric rate, but its finite-dimensional component is asymptotically efficient. Numerical studies show that estimation via a constrained Newton method performs well in terms of both finite sample properties and processing time for moderate-to-large samples with few covariates. We conclude with an application of the proposed methods to assess risk factors for disease progression in psoriatic arthritis.Natural Sciences and Engineering Research Council of Canada (RGPIN 155849); Canadian Institutes for Health Research (FRN 13887); Canada Research Chair (Tier 1) – CIHR funded (950-226626

    The clustering of galaxies at z~0.5 in the SDSS-III Data Release 9 BOSS-CMASS sample: a test for the LCDM cosmology

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    We present results on the clustering of 282,068 galaxies in the Baryon Oscillation Spectroscopic Survey (BOSS) sample of massive galaxies with redshifts 0.4<z<0.7 which is part of the Sloan Digital Sky Survey III project. Our results cover a large range of scales from ~0.5 to ~90 Mpc/h. We compare these estimates with the expectations of the flat LCDM cosmological model with parameters compatible with WMAP7 data. We use the MultiDark cosmological simulation together with a simple halo abundance matching technique, to estimate galaxy correlation functions, power spectra, abundance of subhaloes and galaxy biases. We find that the LCDM model gives a reasonable description to the observed correlation functions at z~0.5, which is a remarkably good agreement considering that the model, once matched to the observed abundance of BOSS galaxies, does not have any free parameters. However, we find a deviation (>~10%) in the correlation functions for scales less than ~1 Mpc/h and ~10-40 Mpc/h. A more realistic abundance matching model and better statistics from upcoming observations are needed to clarify the situation. We also estimate that about 12% of the "galaxies" in the abundance-matched sample are satellites inhabiting central haloes with mass M>~1e14 M_sun/h. Using the MultiDark simulation we also study the real space halo bias b(r) of the matched catalogue finding that b=2.00+/-0.07 at large scales, consistent with the one obtained using the measured BOSS projected correlation function. Furthermore, the linear large-scale bias depends on the number density n of the abundance-matched sample as b=-0.048-(0.594+/-0.02)*log(n/(h/Mpc)^3). Extrapolating these results to BAO scales we measure a scale-dependent damping of the acoustic signal produced by non-linear evolution that leads to ~2-4% dips at ~3 sigma level for wavenumbers k>~0.1 h/Mpc in the linear large-scale bias.Comment: Replaced to match published version. Typos corrected; 25 pages, 17 figures, 9 tables. To appear in MNRAS. Correlation functions (projected and redshift-space) and correlation matrices of CMASS presented in Appendix B. Correlation and covariance data for the combined CMASS sample can be downloaded from http://www.sdss3.org/science/boss_publications.ph

    The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: measurements of the growth of structure and expansion rate at z=0.57 from anisotropic clustering

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    We analyze the anisotropic clustering of massive galaxies from the Sloan Digital Sky Survey III Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 9 (DR9) sample, which consists of 264,283 galaxies in the redshift range 0.43 < z < 0.7 spanning 3,275 square degrees. Both peculiar velocities and errors in the assumed redshift-distance relation ("Alcock-Paczynski effect") generate correlations between clustering amplitude and orientation with respect to the line-of-sight. Together with the sharp baryon acoustic oscillation (BAO) standard ruler, our measurements of the broadband shape of the monopole and quadrupole correlation functions simultaneously constrain the comoving angular diameter distance (2190 +/- 61 Mpc) to z=0.57, the Hubble expansion rate at z=0.57 (92.4 +/- 4.5 km/s/Mpc), and the growth rate of structure at that same redshift (d sigma8/d ln a = 0.43 +/- 0.069). Our analysis provides the best current direct determination of both DA and H in galaxy clustering data using this technique. If we further assume a LCDM expansion history, our growth constraint tightens to d sigma8/d ln a = 0.415 +/- 0.034. In combination with the cosmic microwave background, our measurements of DA, H, and growth all separately require dark energy at z > 0.57, and when combined imply \Omega_{\Lambda} = 0.74 +/- 0.016, independent of the Universe's evolution at z<0.57. In our companion paper (Samushia et al. prep), we explore further cosmological implications of these observations.Comment: 19 pages, 11 figures, submitted to MNRAS, comments welcom

    Acoustic scale from the angular power spectra of SDSS-III DR8 photometric luminous galaxies

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    We measure the acoustic scale from the angular power spectra of the Sloan Digital Sky Survey III (SDSS-III) Data Release 8 imaging catalog that includes 872,921 galaxies over ~ 10,000 deg^2 between 0.45<z<0.65. The extensive spectroscopic training set of the Baryon Oscillation Spectroscopic Survey (BOSS) luminous galaxies allows precise estimates of the true redshift distributions of galaxies in our imaging catalog. Utilizing the redshift distribution information, we build templates and fit to the power spectra of the data, which are measured in our companion paper, Ho et al. 2011, to derive the location of Baryon acoustic oscillations (BAO) while marginalizing over many free parameters to exclude nearly all of the non-BAO signal. We derive the ratio of the angular diameter distance to the sound horizon scale D_A/r_s= 9.212 + 0.416 -0.404 at z=0.54, and therefore, D_A= 1411+- 65 Mpc at z=0.54; the result is fairly independent of assumptions on the underlying cosmology. Our measurement of angular diameter distance D_A is 1.4 \sigma higher than what is expected for the concordance LCDM (Komatsu et al. 2011), in accordance to the trend of other spectroscopic BAO measurements for z >~ 0.35. We report constraints on cosmological parameters from our measurement in combination with the WMAP7 data and the previous spectroscopic BAO measurements of SDSS (Percival et al. 2010) and WiggleZ (Blake et al. 2011). We refer to our companion papers (Ho et al. 2011; de Putter et al. 2011) for investigations on information of the full power spectrum.Comment: 16 pages, 14 figures, 3 tables, submitted to Ap

    Depression and incident HIV in adolescent girls and young women in HPTN 068:Targets for prevention and mediating factors

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    Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health 2019. This work is written by (a) US Government employee(s) and is in the public domain in the US. The human immunodeficiency virus (HIV) epidemic among adolescent girls and young women (AGYW) in sub-Saharan Africa is a critical public health problem. We assessed whether depressive symptoms in AGYW were longitudinally associated with incident HIV, and identified potential social and behavioral mediators. Data came from a randomized trial of a cash transfer conditional on school attendance among AGYW (ages 13-21 years) in rural Mpumalanga Province, South Africa, during 2011-2017. We estimated the relationship between depressive symptoms and cumulative HIV incidence using a linear probability model, and we assessed mediation using inverse odds ratio weighting. Inference was calculated using the nonparametric bootstrap. AGYW with depressive symptoms had higher cumulative incidence of HIV compared with those without (risk difference = 3.5, 95% confidence interval (CI): 0.1, 7.0). The strongest individual mediators of this association were parental monitoring and involvement (indirect effect = 1.6, 95% CI: 0.0, 3.3) and reporting a partner would hit her if she asked him to wear a condom (indirect effect = 1.5, 95% CI: -0.3, 3.3). All mediators jointly explained two-thirds (indirect effect = 2.4, 95% CI: 0.2, 4.5) of the association between depressive symptoms and HIV incidence. Interventions addressing mental health might reduce risk of acquiring HIV among AGYW
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