1,609 research outputs found

    SPEAR Far Ultraviolet Spectral Images of the Cygnus Loop

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    We present far-ultraviolet (FUV) spectral images, measured at C IV 1550, He II 1640, Si IV+O IV] 1400, and O III] 1664, of the entire Cygnus Loop, observed with the Spectroscopy of Plasma Evolution from Astrophysical Radiation (SPEAR) instrument, also known as FIMS. The spatial distribution of FUV emission generally corresponds with a limb-brightened shell, and is similar to optical, radio and X-ray images. The features found in the present work include a ``carrot'', diffuse interior, and breakout features, which have not been seen in previous FUV studies. Shock velocities of 140-160 km/s is found from a line ratio of O IV] to O III], which is insensitive not only to resonance scattering but also to elemental abundance. The estimated velocity indicates that the fast shocks are widespread across the remnant. By comparing various line ratios with steady-state shock models, it is also shown that the resonance scattering is widespread.Comment: 13 pages, 3 figures, 1 table, accepted for publication in ApJ

    Mapping Hydrogen in the Galaxy, Galactic Halo, and Local Group with ALFA: The GALFA-HI Survey Starting with TOGS

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    Radio observations of gas in the Milky Way and Local Group are vital for understanding how galaxies function as systems. The unique sensitivity of Arecibo's 305m dish, coupled with the 7-beam Arecibo L-Band Feed Array (ALFA), provides an unparalleled tool for investigating the full range of interstellar phenomena traced by the HI 21cm line. The GALFA (Galactic ALFA) HI Survey is mapping the entire Arecibo sky over a velocity range of -700 to +700 km/s with 0.2 km/s velocity channels and an angular resolution of 3.4 arcminutes. We present highlights from the TOGS (Turn on GALFA Survey) portion of GALFA-HI, which is covering thousands of square degrees in commensal drift scan observations with the ALFALFA and AGES extragalactic ALFA surveys. This work is supported in part by the National Astronomy and Ionosphere Center, operated by Cornell University under cooperative agreement with the National Science Foundation.Comment: 3 pages, including 2 figure pages; figure image quality significantly reduced; for full resolution version, please see http://www.naic.edu/~gibson/cv/ao08_writeup.pdf ; to be published in AIP conference proceedings for ``The Evolution of Galaxies through the Neutral Hydrogen Window'', eds. R. Minchin & E. Momjia

    Dental students’ and patients’ perceived importance and knowledge of dental anxiety

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    Abstract Aim: To examine the perceived importance and knowledge of the dental students’ in their treatment of dental anxiety according to their year of study and to find out patients’ perceived importance of the dental students’ knowledge of dental anxiety according to their level on dental fear. Methods: Dental students (N = 219) at the University of Turku and non‐probability convenience sample of 100 of patients attending the Dental Teaching Clinic were given questionnaires with multiple choice and open‐ended questions. Students were categorised into three groups according to the year of study (1–3, 4, 5). Patients were categorised into three groups using the established cut points for Modified Dental Anxiety Scale (no fear = 5–9, low fear = 10–18, high fear = 19–25). The differences between groups were evaluated using cross‐tabulations, chi squared and Fisher’s exact tests. The open‐ended questions were subjected to content analysis. Results: Students’ perceived importance of dental anxiety did not differ between three groups. Students with greater undergraduate education and clinical experience were more likely to have excellent or quite good knowledge (P < 0.001). Patients’ perceived importance of dental students’ knowledge of dental anxiety was greater in patients with high level of fear. The overlapping category that emerged from the open‐ended question analysis was communication skills. This appeared to be important for patients with dental anxiety and for dental students in their management of dental anxiety. Conclusion: Clinical communication skills should be part of dental anxiety management teaching. Dental students should be able to gain sufficient knowledge and skills in treating dental anxiety before graduating

    All-Wood Composite Material by Partial Fiber Surface Dissolution with an Ionic Liquid

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    Synthetic structural materials of high mechanical performance are typically either of large weight (for example, steels, and alloys) or involve complex manufacturing processes and thus have high cost or cause adverse environmental impact (for example, polymer-based and biomimetic composites). In this perspective, low-cost, abundant and nature-based materials, such as wood, represent particular interest provided they fulfill the requirements for advanced engineering structures and applications, especially when manufactured totally additive-free. Here, we report on a novel all-wood material concept based on delignification, partial surface dissolution using ionic liquid (IL) followed by densification resulting in a high-performance material. A delignification process using sodium chlorite in acetate buffer solution was applied to controllably delignify the entire bulk wooden material while retaining the highly beneficial structural directionality of wood. In a subsequent step, obtained delignified porous wood template was infiltrated with an IL 1-ethyl-3-methylimidazolium acetate, [EMIM]OAc and heat activated at 95 degrees C to partially dissolve the fiber surface. Afterward, treated wood was washed with water to remove IL and hot-pressed to gain a very compact cellulosic material with fused fibers while retaining unidirectional fiber orientation. The obtained cellulose materials were structurally, chemically, and mechanically characterized revealing superior tensile properties compared to native wood. Furthermore, suggested approach allows almost 8-fold tensile strength improvement in the direction perpendicular to fiber orientation, which is otherwise very challenging to achieve.Peer reviewe

    Analysis of Spatial Structure of the SPica H II Region

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    Far ultraviolet (FUV) spectral images of the Spica H II region are first presented here for the Si II* 1533.4A and Al II 1670.8A lines and then compared with the optical Halpha image. The H alpha and Si II* images show enhanced emissions in the southern part of the H II region where H I density increases outwards. This high density region, which we identify as part of the "interaction ring" of the Loop I superbubble and the Local Bubble, seems to bound the southern H II region. On the other hand, the observed profile of Al II shows a broad central peak, without much difference between the northern and southern parts, which we suspect results from multiple resonant scattering. The extended tails seen in the radial profiles of the FUV intensities suggest that the nebula may be embedded in a warm ionized gas. Simulation with a spectral synthesis code yields the values of the Lyman continuum luminosity and the effective temperature of the central star similar to previous estimates with 10^46.2 photons s^-1 and 26,000 K, respectively, but the density of the northern H II region, 0.22 cm^-3, is much smaller than previous estimates for the H alpha brightest region.Comment: 15 pages, 5 figures, accepted for Ap

    Antibiotics in early life associate with specific gut microbiota signatures in a prospective longitudinal infant cohort

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    BACKGROUND The effects of antibiotics on infant gut microbiota are unclear. We hypothesized that the use of common antibiotics results in long-term aberration in gut microbiota. METHODS Antibiotic-naive infants were prospectively recruited when hospitalized because of a respiratory syncytial virus infection. Composition of fecal microbiota was compared between those receiving antibiotics during follow-up (prescribed at clinicians' discretion because of complications such as otitis media) and those with no antibiotic exposure. Fecal sampling started on day 1, then continued at 2-day intervals during the hospital stay, and at 1, 3 and 6 months at home. RESULTS One hundred and sixty-three fecal samples from 40 patients (median age 2.3 months at baseline; 22 exposed to antibiotics) were available for microbiota analyses. A single course of amoxicillin or macrolide resulted in aberration of infant microbiota characterized by variation in the abundance of bifidobacteria, enterobacteria and clostridia, lasting for several months. Recovery from the antibiotics was associated with an increase in clostridia. Occasionally, antibiotic use resulted in microbiota profiles associated with inflammatory conditions. CONCLUSIONS Antibiotic use in infants modifies especially bifidobacterial levels. Further studies are warranted whether administration of bifidobacteria will provide health benefits by normalizing the microbiota in infants receiving antibiotics.Peer reviewe

    Childhood BMI in relation to microbiota in infancy and lifetime antibiotic use

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    Background: Children with high body mass index (BMI) at preschool age are at risk of developing obesity. Early identification of factors that increase the risk of excessive weight gain could help direct preventive actions. The intestinal microbiota and antibiotic use have been identified as potential modulators of early metabolic programming and weight development. To test if the early microbiota composition is associated with later BMI, and if antibiotic use modifies this association, we analysed the faecal microbiota composition at 3 months and the BMI at 5-6 years in two cohorts of healthy children born vaginally at term in the Netherlands (N = 87) and Finland (N = 75). We obtained lifetime antibiotic use records and measured weight and height of all children. Results: The relative abundance of streptococci was positively and the relative abundance of bifidobacteria negatively associated with the BMI outcome. The association was especially strong among children with a history of antibiotic use. Bacteroides relative abundance was associated with BMI only in the children with minimal lifetime antibiotic exposure. Conclusions: The intestinal microbiota of infants are predictive of later BMI and may serve as an early indicator of obesity risk. Bifidobacteria and streptococci, which are indicators of microbiota maturation in infants, are likely candidates for metabolic programming of infants, and their influence on BMI appears to depend on later a\ntibiotic use.Peer reviewe
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