| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Bland-Hawthorn, Joss, et al.
(författare)
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The GALAH survey and Gaia DR2 : dissecting the stellar disc's phase space by age, action, chemistry, and location
- 2019
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Ingår i: Monthly notices of the Royal Astronomical Society. - : OXFORD UNIV PRESS. - 0035-8711 .- 1365-2966. ; 486:1, s. 1167-1191
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Tidskriftsartikel (refereegranskat)abstract
- We use the second data releases of the European Space Agency Gaia astrometric survey and the high-resolution Galactic Archaeology with HERMES (GALAH) spectroscopic survey to analyse the structure of our Galaxy's disc components. With GALAH, we separate the alpha-rich and alpha-poor discs (with respect to Fe), which are superposed in both position and velocity space, and examine their distributions in action space. We study the distribution of stars in the zV(z) phase plane, for both V-phi and V-R, and recover the remarkable 'phase spiral' discovered by Gaia. We identify the anticipated quadrupole signature in zV(z) of a tilted velocity ellipsoid for stars above and belowtheGalactic plane. By connecting ourwork with earlier studies, we show that the phase spiral is likely to extend well beyond the narrow solar neighbourhood cylinder in which it was found. The phase spiral is a signature of corrugated waves that propagate through the disc, and the associated non-equilibrium phase mixing. The radially asymmetric distribution of stars involved in the phase spiral reveals that the corrugation, which is mostly confined to the alpha-poor disc, grows in z-amplitude with increasing radius. We present new simulations of tidal disturbance of the Galactic disc by the Sagittarius (Sgr) dwarf. The effect on the zV(z) phase plane lasts greater than or similar to 2 Gyr, but a subsequent disc crossing wipes out the coherent structure. We find that the phase spiral was excited less than or similar to 0.5 Gyr ago by an object like Sgr with total mass similar to 3 x 10(10) M-circle dot (stripped down from similar to 5 x 10(10) M-circle dot when it first entered the halo) passing through the plane.
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| 3. |
- Grant, Marcus, et al.
(författare)
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Cities and health: an evolving global conversation
- 2017
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Ingår i: Cities and Health. - : Informa UK Limited. - 2374-8834 .- 2374-8842. ; 1:1, s. 1-9
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The Cities and Health journal sees its launch in 2017. Looking back over half a century of growth and global expansion in economic activity, although there have been societal benefits, negative impacts are starting to take their toll on planetary resources and human health. As we enter what is being termed The Anthropocene, the city is becoming the preferred habitat for humanity. The imprint of city lifestyles, in terms of both resource use and waste, is found across the globe, threatening the ecosystem services that support our health. In cities themselves, due to risks and challenges to health, we are witnessing a rise in non-communicable disease, twinned with infectious disease for the many who live increasingly in informal or slum urban development. High levels of health inequity are found within urban populations. The resultant health problems are placing increasing strain on health services, with pressure only set to increase due to continuing urbanization and ageing populations. Evidence increasingly demonstrates that many aspects of city and neighbourhood form, urban and transport design, and residential environments play an important role in mediating health and health equity outcomes. The new journal Cities & Health is being launched to support political, academic and technical leadership and transdisciplinarity in this field. For this endeavour we will need to re-examine the nature of evidence required before we act; to explore how academics, policy-makers, practitioners and communities can best collaborate using the city as a laboratory for change; and to develop capacity building for healthier place-making at professional and community levels.
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