670 research outputs found

    Small herbaria contribute unique biogeographic records to county, locality, and temporal scales

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    With digitization and data sharing initiatives underway over the last 15 years, an important need has been prioritizing specimens to digitize. Because duplicate specimens are shared among herbaria in exchange and gift programs, we investigated the extent to which unique biogeographic data are held in small herbaria vs. these data being redundant with those held by larger institutions. We evaluated the unique specimen contributions that small herbaria make to biogeographic understanding at county, locality, and temporal scales

    Power analysis in health policy and systems research: A guide to research conceptualisation

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    Power is a growing area of study for researchers and practitioners working in the field of health policy and systems research (HPSR). Theoretical development and empirical research on power are crucial for providing deeper, more nuanced understandings of the mechanisms and structures leading to social inequities and health disparities; placing contemporary policy concerns in a wider historical, political and social context; and for contributing to the (re)design or reform of health systems to drive progress towards improved health outcomes. Nonetheless, explicit analyses of power in HPSR remain relatively infrequent, and there are no comprehensive resources that serve as theoretical and methodological starting points. This paper aims to fill this gap by providing a consolidated guide to researchers wishing to consider, design and conduct power analyses of health policies or systems. This practice article presents a synthesis of theoretical and conceptual understandings of power; describes methodologies and approaches for conducting power analyses; discusses how they might be appropriately combined; and throughout reflects on the importance of engaging with positionality through reflexive praxis. Expanding research on power in health policy and systems will generate key insights needed to address underlying drivers of health disparities and strengthen health systems for all

    Effect of Advanced HIV Infection on the Respiratory Microbiome

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    RATIONALE: Previous work found the lung microbiome in healthy subjects infected with HIV was similar to that in uninfected subjects. We hypothesized the lung microbiome from subjects infected with HIV with more advanced disease would differ from that of an uninfected control population. OBJECTIVES: To measure the lung microbiome in an HIV-infected population with advanced disease. METHODS: 16s RNA gene sequencing was performed on acellular bronchoalveolar lavage (BAL) fluid from 30 subjects infected with HIV with advanced disease (baseline mean CD4 count, 262 cells/mm(3)) before and up to 3 years after starting highly active antiretroviral therapy (HAART) and compared with 22 uninfected control subjects. MEASUREMENTS AND MAIN RESULTS: The lung microbiome in subjects infected with HIV with advanced disease demonstrated decreased alpha diversity (richness and diversity) and greater beta diversity compared with uninfected BAL. Differences improved with HAART, but still persisted up to 3 years after starting therapy. Population dispersion in the group infected with HIV was significantly greater than in the uninfected cohort and declined after treatment. There were differences in the relative abundance of some bacteria between the two groups at baseline and after 1 year of therapy. After 1 year on HAART, HIV BAL contained an increased abundance of Prevotella and Veillonella, bacteria previously associated with lung inflammation. CONCLUSIONS: The lung microbiome in subjects infected with HIV with advanced disease is altered compared with an uninfected population both in diversity and bacterial composition. Differences remain up to 3 years after starting HAART. We speculate an altered lung microbiome in HIV infection may contribute to chronic inflammation and lung complications seen in the HAART era

    Unusual raptor nests around the world

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    From surveys in many countries, we report using unusual nesting materials (e.g., paper money, rags, metal, antlers, and large bones) and unusual nesting situations. For example, we documented nests of Steppe Eagles [Aquila nipalensis] and Upland Buzzards [Buteo hemilasius] on the ground beside well-traveled roads, Saker Falcon [Falco cherrug] eyries in attics and a cistern, and Osprey [Pandian haliaetus] nests on the masts of boats and on a suspended automobile. Other records include a Golden Eagle [A. chrysaelos] nest 7.0 m in height, believed to be the tallest nest ever described, and, for the same species, we report nesting in rudimentary, nests. Some nest sites are within a Few meters of known predators or competitors. These unusual observations may be important in revealing the plasticity of a species' behavioral repertoire

    The First Quiescent Galaxies in TNG300

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    We identify the first quiescent galaxies in TNG300, the largest volume of the IllustrisTNG cosmological simulation suite, and explore their quenching processes and time evolution to z=0. We find that the first quiescent galaxies with stellar masses M_* > 3 x 10^{10} M_sun and specific star formation rates sSFR < 10^{-11} yr^{-1} emerge at z~4.2 in TNG300. Suppression of star formation in these galaxies begins with a thermal mode of AGN feedback at z~6, and a kinetic feedback mode acts in each galaxy by z~4.7 to complete the quenching process, which occurs on a time-scale of ~0.35 Gyr. Surprisingly, we find that the majority of these galaxies are not the main progenitors of their z=0 descendants; instead, four of the five galaxies fall into more massive galaxies in subsequent mergers at a range of redshifts 2.5 < z < 0.2. By z=0, these descendants are the centres of galaxy clusters with average stellar masses of 8 x 10^{11} M_sun. We make predictions for the first quenched galaxies to be located by the James Webb Space Telescope (JWST).Comment: 6 pages, 4 figure

    JWST Reveals Widespread AGN-Driven Neutral Gas Outflows in Massive z ~ 2 Galaxies

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    We use deep JWST/NIRSpec R~1000 slit spectra of 113 galaxies at 1.7 < z < 3.5, selected from the mass-complete Blue Jay survey, to investigate the prevalence and typical properties of neutral gas outflows at cosmic noon. We detect excess Na I D absorption (beyond the stellar contribution) in 46% of massive galaxies (log\log M_*/M>_\odot > 10), with similar incidence rates in star-forming and quenching systems. Half of the absorption profiles are blueshifted by at least 100 km/s, providing unambiguous evidence for neutral gas outflows. Galaxies with strong Na I D absorption are distinguished by enhanced emission line ratios consistent with AGN ionization. We conservatively measure mass outflow rates of 3 - 100 MM_\odot yr1^{-1}; comparable to or exceeding ionized gas outflow rates measured for galaxies at similar stellar mass and redshift. The outflows from the quenching systems (log(sSFR)[yr1^{-1}] \lesssim -10) have mass loading factors of 4 - 360, and the energy and momentum outflow rates exceed the expected injection rates from supernova explosions, suggesting that these galaxies could possibly be caught in a rapid blowout phase powered by the AGN. Our findings suggest that AGN-driven ejection of cold gas may be a dominant mechanism for fast quenching of star formation at z~2.Comment: 16 pages, 8 figures, submitted to MNRA

    Structural Evolution in Massive Galaxies at z ~ 2

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    We present 0.2arcsec-resolution Atacama Large Millimeter/submillimeter Array observations at 870 μ\mum in a stellar mass-selected sample of 85 massive (Mstar>1011 MM_\mathrm{star}>10^{11}~M_\odot) star-forming galaxies (SFGs) at z=1.9-2.6 in the 3D-HST/CANDELS fields of UDS and GOODS-S. We measure the effective radius of the rest-frame far-infrared (FIR) emission for 62 massive SFGs. They are distributed over wide ranges of FIR size from Re,FIR=R_\mathrm{e,FIR}=0.4 kpc to Re,FIR=R_\mathrm{e,FIR}=6 kpc. The effective radius of the FIR emission is smaller by a factor of 2.31.0+1.9^{+1.9}_{-1.0} than the effective radius of the optical emission and by a factor of 1.91.0+1.9^{+1.9}_{-1.0} smaller than the half-mass radius. Even with taking into account potential extended components, the FIR size would change by ~10%. By combining the spatial distributions of the FIR and optical emission, we investigate how galaxies change the effective radius of the optical emission and the stellar mass within a radius of 1 kpc, M1kpcM_\mathrm{1kpc}. The compact starburst puts most of massive SFGs on the mass--size relation for quiescent galaxies (QGs) at z~2 within 300 Myr if the current star formation activity and its spatial distribution are maintained. We also find that within 300 Myr, ~38% of massive SFGs can reach the central mass of M1kpc=1010.5 MM_\mathrm{1kpc}=10^{10.5}~M_\odot, which is around the boundary between massive SFGs and QGs. These results suggest an outside-in transformation scenario in which a dense core is formed at the center of a more extended disk, likely via dissipative in-disk inflows. Synchronized observations at ALMA 870 μ\mum and JWST 3-4 μ\mum will explicitly verify this scenario.Comment: 25 pages, 15 figures, 3 tables, accepted for publication in Ap
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