716 research outputs found

    C II abundances in early-type stars: solution to a notorious non-LTE problem

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    We address a long-standing discrepancy between non-LTE analyses of the prominent C II 4267 and 6578/82 A multiplets in early-type stars. A comprehensive non-LTE model atom of C II is constructed based on critically selected atomic data. This model atom is used for an abundance study of six apparently slow-rotating main-sequence and giant early B-type stars. High-resolution and high-S/N spectra allow us to derive highly consistent abundances not only from the classical features but also from up to 18 further C II lines in the visual - including two so far unreported emission features equally well reproduced in non-LTE. These results require the stellar atmospheric parameters to be determined with care. A homogeneous (slightly) sub-solar present-day carbon abundance from young stars in the solar vicinity (in associations and in the field) of log C/H +12= 8.29+/-0.03 is indicated.Comment: 8 pages, 5 figure

    Anxiety, Stress, Depression, and Patients’ Responses to Periodontal Treatment: Periodontists’ Knowledge and Professional Behavior

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142063/1/jper0064.pd

    Phase behaviors of binary mixtures composed of banana-shaped and calamitic mesogens

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    In this work, five mixtures with different concentrations of banana-shaped and calamitic compounds have been prepared and subsequently studied by polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction on non-oriented samples. The phase sequences and molecular parameters of the binary systems are presented

    Cascading effects of canopy mortality drive long-term changes in understorey diversity in temperate old-growth forests of Europe

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    Questions: We investigated the influence of protracted mortality of a dominant canopy tree (Abies alba) on long-term understorey dynamics. We ask (a) how tree regeneration and understorey species diversity and composition changed over 32 years; and (b) whether the observed changes were mainly driven by mortality of A. alba. Location: Three old-growth forest reserves dominated by A. alba and Fagus sylvatica in the Dinaric Mountains of Slovenia. Method: Tree layer and understorey regeneration and herbs were surveyed in 147 plots across the three forest reserves in 1983 and 2015. Soils were also sampled in 2015. The study period coincides with a protracted period of increased A. alba mortality in the canopy layer associated with anthropogenic emissions. Results: Between 1983 and 2015, the decline in canopy layer A. alba caused a recruitment pulse of F. sylvatica regeneration to the subcanopy tree layer across the three reserves. These changes were accompanied by a significant decline in plot level herb species richness. A model-based analysis of beta-diversity revealed significant community convergence during the study period, mainly caused by the loss of rare species. Ellenberg values indicate that these changes were mainly driven by loss of understorey light, while an increase in soil pH may have played a role also. Conclusions: This observational study suggests that the long-term decline of A. alba resulted in a cascade of processes - widespread F. sylvatica recruitment that impeded penetration of light to the forest floor, and possibly a change in soil conditions due to the decline of coniferous litter. These changes caused a significant loss of herb diversity and homogenization of the understorey community across the three sites. This study sheds light on the potential cascading consequences triggered by episodes of increased tree mortality resulting from global-change-type drivers

    Characterization of Periodontal Structures of Enamelinâ Null Mice

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141513/1/jper0195.pd

    The role of nicotinamide in acne treatment

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    Safe and effective treatment options for acne vulgaris are needed to address side effects and increasing rates of antibiotic resistance from current treatments. Nicotinamide is a vitamin with potent antiâ inflammatory properties that could offer a potential treatment option. We aim to summarize the relevant literature on the role of nicotinamide in acne vulgaris and discuss the next steps necessary to move this approach into clinical practice. We searched PubMed for clinical studies using nicotinamide for treatment of acne vulgaris. We summarized the 10 studies that met our search criteria. Six of eight studies using topical nicotinamide led to a significant reduction in acne compared with the patient’s baseline or performed similarly to another standardâ ofâ care acne treatment. Both studies using an oral supplement containing nicotinamide resulted in a significant reduction in acne compared with baseline. No major adverse side effects were noted. Our review suggests that topical and oral nicotinamide has an unclear effect on acne vulgaris due to the limited nature of the available literature. Additional studies are needed comparing nicotinamide to other firstâ line acne treatments and evaluating the efficacy and side effect profile of nicotinamide over an extended period of time.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138875/1/dth12481_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138875/2/dth12481.pd

    Comparison of Two Differently Processed Acellular Dermal Matrix Products for Root Coverage Procedures: A Prospective, Randomized Multicenter Study

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141116/1/jper1693-sup-0001.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141116/2/jper1693.pd
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