207 research outputs found

    Beyond the Brim of the Hat: Kinematics of Globular Clusters out to Large Radius in the Sombrero Galaxy

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    We have obtained radial velocity measurements for 51 new globular clusters around the Sombrero galaxy. These measurements were obtained using spectroscopic observations from the AAOmega spectrograph on the Anglo-Australian Telescope and the Hydra spectrograph at WIYN. Combined with our own past measurements and velocity measurements obtained from the literature we have constructed a large database of radial velocities that contains a total of 360 confirmed globular clusters. Previous studies' analyses of the kinematics and mass profile of the Sombrero globular cluster system have been constrained to the inner ~9' (~24 kpc or ~5 effective radii), but our new measurements have increased the radial coverage of the data, allowing us to determine the kinematic properties of M104 out to ~15' (~41 kpc or ~9 effective radii). We use our set of radial velocities to study the GC system kinematics and to determine the mass profile and V-band mass-to-light profile of the galaxy. We find that the V-band mass-to-light ratio increases from 4.5 at the center to a value of 20.9 at 41 kpc (~9 effective radii or 15'), which implies that the dark matter halo extends to the edge of our available data set. We compare our mass profile at 20 kpc (~4 effective radii or ~7.4') to the mass computed from x-ray data and find good agreement. We also use our data to look for rotation in the globular cluster system as a whole, as well as in the red and blue subpopulations. We find no evidence for significant rotation in any of these samples.Comment: Accepted for publication in the Astronomical Journal; 23 pages, 14 figures, and 2 table

    Sodium content as a predictor of the advanced evolution of globular cluster stars

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    The asymptotic giant branch (AGB) phase is the final stage of nuclear burning for low-mass stars. Although Milky Way globular clusters are now known to harbour (at least) two generations of stars they still provide relatively homogeneous samples of stars that are used to constrain stellar evolution theory. It is predicted by stellar models that the majority of cluster stars with masses around the current turn-off mass (that is, the mass of the stars that are currently leaving the main sequence phase) will evolve through the AGB phase. Here we report that all of the second-generation stars in the globular cluster NGC 6752 -- 70 per cent of the cluster population -- fail to reach the AGB phase. Through spectroscopic abundance measurements, we found that every AGB star in our sample has a low sodium abundance, indicating that they are exclusively first-generation stars. This implies that many clusters cannot reliably be used for star counts to test stellar evolution timescales if the AGB population is included. We have no clear explanation for this observation.Comment: Published in Nature (online 29 May 2013, hard copy 13 June), 12 pages, 3 figures + supplementary information sectio

    Metagenomic analysis of DNA viruses with targeted sequence capture of canine lobular orbital adenomas and normal conjunctiva

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    Our study aims are: (1) to evaluate phenotypically normal canine conjunctival and orbital tissue and tissue from canine lobular orbital adenomas (CLOAs) for the presence of viral genomic material and (2) phylogenetically classify detected DNA viruses to determine if a DNA virus is associated with CLOAs. A total of 31 formalin fixed paraffin embedded CLOA tissue samples, 4 papillomas or sarcoid, and 10 fresh clinically normal conjunctival tissues were included in this study. Genomic DNA was isolated from all samples and sequencing libraries were prepared. The libraries were molecularly indexed and pooled and viral DNA was enriched via targeted sequence capture utilizing ViroCap. The libraries were sequenced on the Illumina HiSeq platform and compared to known viral DNA reference genomes to identify viral DNA. Carnivore parvovirus was identified in 6.4% and 20% of CLOA tissue and normal conjunctival samples, respectively. This study showed that conjunctival tissue from healthy dogs and CLOAs uncommonly harbor DNA viruses, and no DNA virus was associated with these tumors. Further studies are needed to evaluate the etiologic cause of CLOAs

    Ageing well with diabetes: A workshop to co‐design research recommendations for improving the diabetes care of older people

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    Aims:To identify key research questions where answers could improve care for older people living with diabetes (PLWD), and provide detailed recommendations for researchers and research funders on how best to address them.Methods:A series of online research workshops were conducted, bringing together a range of PLWD and an acknowledged group of academic and clinical experts in their diabetes care to identify areas for future research. Throughout the pre-workshop phase, during each workshop, and in manuscript preparation and editing, PLWD played an active and dynamic role in discussions as part of both an iterative and narrative process.Results:The following key questions in this field were identified, and research recommendations for each were developed:How can we improve our understanding of the characteristics of older people living with diabetes (PLWD) and their outcomes, and can this deliver better person-centred care?How are services to care for older PLWD currently delivered, both for their diabetes and other conditions? How can we optimise and streamline the process and ensure everyone gets the best care, tailored to their individual needs?What tools might be used to evaluate the level of understanding of diabetes in the older population amongst non-specialist Healthcare Professionals (HCPs)?How can virtual experts or centres most effectively provide access to specialist multi-disciplinary team (MDT) expertise for older PLWD and the HCPs caring for them?Is a combination of exercise and a nutrition-dense, high protein diet effective in the prevention of the adverse effects of type 2 diabetes and deterioration in frailty, and how might this be delivered in a way which is acceptable to people with type 2 diabetes?How might we best use continuous glucose monitoring (CGM) in older people and, for those who require support, how should the data be shared?How can older PLWD be better empowered to manage their diabetes in their own home, particularly when living with additional long-term conditions?What are the benefits of models of peer support for older PLWD, both when living independently and when in care?Conclusions:This paper outlines recommendations supported by PLWD through which new research could improve their diabetes care and calls on the research community and funders to address them in future research programmes and strategies

    Direct Analysis of Aerosolized Chemical Warfare Simulants Captured on a Modified Glass-Based Substrate by “Paper-Spray” Ionization

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    Paper spray ionization mass spectrometry offers a rapid alternative platform requiring no sample preparation. Aerosolized chemical warfare agent (CWA) simulants trimethyl phosphate, dimethyl methylphosphonate, and diisopropyl methylphosphonate were captured by passing air through a glass fiber filter disk within a disposable paper spray cartridge. CWA simulants were aerosolized at varying concentrations using an in-house built aerosol chamber. A custom 3D-printed holder was designed and built to facilitate the aerosol capture onto the paper spray cartridges. The air flow through each of the collection devices was maintained equally to ensure the same volume of air sampled across methods. Each approach yielded linear calibration curves with R2 values between 0.98–0.99 for each compound and similar limits of detection in terms of disbursed aerosol concentration. While the glass fiber filter disk has a higher capture efficiency (≈40%), the paper spray method produces analogous results even with a lower capture efficiency (≈1%). Improvements were made to include glass fiber filters as the substrate within the paper spray cartridge consumable. Glass fiber filters were then treated with ammonium sulfate to decrease chemical interaction with the simulants. This allowed for improved direct aerosol capture efficiency (>40%). Ultimately, the limits of detection were reduced to levels comparable to current worker population limits of 1 × 10–6 mg/m3

    Cyanogen in NGC 1851 red giant branch and asymptotic giant branch stars: Quadrimodal distributions

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    The Galactic globular cluster NGC 1851 has raised much interest since Hubble Space Telescope photometry revealed that it hosts a double subgiant branch. Here we report on our homogeneous study into the cyanogen (CN) band strengths in the red giant branc

    Argos - III. Stellar populations in the galactic bulge of the milky way

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    We present the metallicity results from the ARGOS spectroscopic survey of the Galactic bulge. Our aim is to understand the formation of the Galactic bulge: did it form via mergers, as expected from Λ cold dark matter theory, or from disc instabilities,
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