83 research outputs found
Towards a fully consistent Milky Way disc model: Part 1 The local model based on kinematic and photometric data
We present a fully consistent evolutionary disc model of the solar cylinder.
The model is based on a sequence of stellar sub-populations described by the
star formation history (SFR) and the dynamical heating law (given by the
age-velocity dispersion relation AVR). The combination of kinematic data from
Hipparcos and the finite lifetimes of main sequence (MS) stars enables us to
determine the detailed vertical disc structure independent of individual
stellar ages and only weakly dependent on the IMF. The disc parameters are
determined by applying a sophisticated best fit algorithm to the MS star
velocity distribution functions in magnitude bins. We find that the AVR is well
constrained by the local kinematics, whereas for the SFR the allowed range is
larger. A simple chemical enrichment model is included in order to fit the
local metallicity distribution of G dwarfs. In our favoured model A the power
law index of the AVR is 0.375 with a minimum and maximum velocity dispersion of
5.1 km/s and 25.0 km/s, respectively. The SFR shows a maximum 10 Gyr ago and
declines by a factor of four to the present day value of 1.5 M_sun/pc^2/Gyr. A
best fit of the IMF leads to power-law indices of -1.46 below and -4.16 above
1.72 M_sun avoiding a kink at 1 M_sun. An isothermal thick disc component with
local density of ~6% of the stellar density is included. A thick disc
containing more than 10% of local stellar mass is inconsistent with the local
kinematics of K and M dwarfs.Comment: 20 pages, 18 figs., accepted by MNRA
The Century Survey Galactic Halo Project III: A Complete 4300 deg^2 Survey of Blue Horizontal Branch Stars in the Metal-Weak Thick Disk and Inner Halo
We present a complete spectroscopic survey of 2414 2MASS-selected blue
horizontal branch (BHB) candidates selected over 4300 deg^2 of the sky. We
identify 655 BHB stars in this non-kinematically selected sample. We calculate
the luminosity function of field BHB stars and find evidence for very few hot
BHB stars in the field. The BHB stars located at a distance from the Galactic
plane |Z|<4 kpc trace what is clearly a metal-weak thick disk population, with
a mean metallicity of [Fe/H]= -1.7, a rotation velocity gradient of
dv_{rot}/d|Z|= -28+-3.4 km/s in the region |Z|<6 kpc, and a density scale
height of h_Z= 1.26+-0.1 kpc. The BHB stars located at 5<|Z|<9 kpc are a
predominantly inner-halo population, with a mean metallicity of [Fe/H]= -2.0
and a mean Galactic rotation of -4+-31 km/s. We infer the density of halo and
thick disk BHB stars is 104+-37 kpc^-3 near the Sun, and the relative
normalization of halo to thick-disk BHB stars is 4+-1% near the Sun.Comment: 12 pages in emulateapj format, accepted for publication in February
A
Self-Management of Unpleasant Auditory Hallucinations: A Tested Practice Model
Individuals who experience auditory hallucinations (AH) frequently report hearing unpleasant voices saying disturbing things to them, making derogatory remarks about them, or commanding them to do something, including harming themselves or someone else. The Self-Management of Unpleasant Auditory Hallucinations Practice Model was developed to help psychiatric-mental health nurses in both inpatient and outpatient settings implement evidence-based nursing care for voice hearers who are distressed by unpleasant voices. The model\u27s utility extends to nursing education, administration, and research. The model is comprised of three parts: (a) Assessment of Voice Hearer\u27s Experience, (b) Nursing Interventions, and (c) Voice Hearer\u27s Expected Positive Outcomes. These three parts of the model describe nursing assessments conducted with an interview guide and two self-report tools, nursing interventions that teach strategies to manage unpleasant AH in a 10-session course or individually, and evaluation of voice hearer outcomes with two self-report tools
The surface brightness of the Galaxy at the Solar Neighbourhood
We present a new determination of the surface brightness of our Galaxy at the
Solar Neighbourhood as observed from outside the Galaxy. We rely on various
existing optical and infra-red surveys to obtain a multiwavelength estimate. On
the one hand, scattered light does not contribute significantly to the surface
brightness. On the other hand, optical and infrared integrated all-sky surveys
(Pioneer 10/11 and COBE/DIRBE) show a systematically larger value than our
synthetic local estimate based on Hipparcos data. This local estimate is also
compatible with our Galactic simulations normalised at the Solar Neighbourhood
and assuming an homogeneous stellar distribution. We interpret this
disagreement as a signature of the presence of a local minimum of the stellar
density compatible with Gould's belt. According to this result, the global
luminosity of the Milky Way should follow the Tully-Fisher relation established
for external galaxies.Comment: 27 pages (including 13 pages of appendices), 45 figures; accepted for
publication in Astronomy and Astrophysic
Human factors in the design of sustainable built environments
Scientific research provides convincing evidence that climate change is having significant impacts on many aspects of life. In the built-environment domain, regulatory requirements are pushing the challenges of environmental, economic, and social sustainability at the core of the professional agenda, although the aims of carbon reduction and energy conservation are frequently given a priority over occupants' comfort, well-being, and satisfaction. While most practitioners declare to embrace sustainability as a driver of their professional approach, a general lack of integrated creative and technical skills hinders the design of buildings centred on articulate and comprehensive sustainability goals, encompassing, other than energy criteria, also human-centred and ethical values founded on competent and informed consideration of the requirements of the site, the programme, and the occupants. Built environments are designed by humans to host a range of human activities. In response, this article aims to endorse a sustainable approach to design founded on the knowledge arising from scholarly and evidence-based research, exploring principles and criteria for the creation and operation of human habitats that can respond to energy and legislative demands, mitigate their environmental impacts, and adapt to new climate scenarios, while elevating the quality of experience and delight to those occupying them
Paramedic assessment of older adults after falls, including community care referral pathway : cluster randomized trial
Study objective
We aim to determine clinical and cost-effectiveness of a paramedic protocol for the care of older people who fall.
Methods
We undertook a cluster randomized trial in 3 UK ambulance services between March 2011 and June 2012. We included patients aged 65 years or older after an emergency call for a fall, attended by paramedics based at trial stations. Intervention paramedics could refer the patient to a community-based falls service instead of transporting the patient to the emergency department. Control paramedics provided care as usual. The primary outcome was subsequent emergency contacts or death.
Results
One hundred five paramedics based at 14 intervention stations attended 3,073 eligible patients; 110 paramedics based at 11 control stations attended 2,841 eligible patients. We analyzed primary outcomes for 2,391 intervention and 2,264 control patients. One third of patients made further emergency contacts or died within 1 month, and two thirds within 6 months, with no difference between groups. Subsequent 999 call rates within 6 months were lower in the intervention arm (0.0125 versus 0.0172; adjusted difference –0.0045; 95% confidence interval –0.0073 to –0.0017). Intervention paramedics referred 8% of patients (204/2,420) to falls services and left fewer patients at the scene without any ongoing care. Intervention patients reported higher satisfaction with interpersonal aspects of care. There were no other differences between groups. Mean intervention cost was $23 per patient, with no difference in overall resource use between groups at 1 or 6 months.
Conclusion
A clinical protocol for paramedics reduced emergency ambulance calls for patients attended for a fall safely and at modest cost
The kinematic signature of the Galactic warp in Gaia DR1 : I. the H ipparcos subsample
Reproduced with permission from Astronomy & Astrophysics, © 2017 ESO.Context. The mechanism responsible for the warp of our Galaxy, as well as its dynamical nature, continues to remain unknown. With the advent of high precision astrometry, new horizons have been opened for detecting the kinematics associated with the warp and for constraining possible warp formation scenarios for the Milky Way. Aims. The aim of this contribution is to establish whether the first Gaia data release (DR1) shows significant evidence of the kinematic signature expected from a long-lived Galactic warp in the kinematics of distant OB stars. As the first paper in a series, we present our approach for analyzing the proper motions and apply it to the subsample of Hipparcos stars. Methods. We select a sample of 989 distant spectroscopically-identified OB stars from the new reduction of Hipparcos, of which 758 are also in the first Gaia data release (DR1), covering distances from 0.5 to 3 kpc from the Sun. We develop a model of the spatial distribution and kinematics of the OB stars from which we produce the probability distribution functions of the proper motions, with and without the systematic motions expected from a long-lived warp. A likelihood analysis is used to compare the expectations of the models with the observed proper motions from both Hipparcos and Gaia DR1. Results. We find that the proper motions of the nearby OB stars are consistent with the signature of a kinematic warp, while those of the more distant stars (parallax <1 mas) are not. Conclusions. The kinematics of our sample of young OB stars suggests that systematic vertical motions in the disk cannot be explained by a simple model of a stable long-lived warp. The warp of the Milky Way may either be a transient feature, or additional phenomena are acting on the gaseous component of the Milky Way, causing systematic vertical motions that are masking the expected warp signal. A larger and deeper sample of stars with Gaia astrometry will be needed to constrain the dynamical nature of the Galactic warp.Peer reviewe
An Incomplete TCA Cycle Increases Survival of Salmonella Typhimurium during Infection of Resting and Activated Murine Macrophages
In comparison to the comprehensive analyses performed on virulence gene expression, regulation and action, the intracellular metabolism of Salmonella during infection is a relatively under-studied area. We investigated the role of the tricarboxylic acid (TCA) cycle in the intracellular replication of Salmonella Typhimurium in resting and activated macrophages, epithelial cells, and during infection of mice.We constructed deletion mutations of 5 TCA cycle genes in S. Typhimurium including gltA, mdh, sdhCDAB, sucAB, and sucCD. We found that the mutants exhibited increased net intracellular replication in resting and activated murine macrophages compared to the wild-type. In contrast, an epithelial cell infection model showed that the S. Typhimurium ΔsucCD and ΔgltA strains had reduced net intracellular replication compared to the wild-type. The glyoxylate shunt was not responsible for the net increased replication of the TCA cycle mutants within resting macrophages. We also confirmed that, in a murine infection model, the S. Typhimurium ΔsucAB and ΔsucCD strains are attenuated for virulence.Our results suggest that disruption of the TCA cycle increases the ability of S. Typhimurium to survive within resting and activated murine macrophages. In contrast, epithelial cells are non-phagocytic cells and unlike macrophages cannot mount an oxidative and nitrosative defence response against pathogens; our results show that in HeLa cells the S. Typhimurium TCA cycle mutant strains show reduced or no change in intracellular levels compared to the wild-type. The attenuation of the S. Typhimurium ΔsucAB and ΔsucCD mutants in mice, compared to their increased net intracellular replication in resting and activated macrophages suggest that Salmonella may encounter environments within the host where a complete TCA cycle is advantageous
NBEAL2 is required for neutrophil and NK cell function and pathogen defense.
Mutations in the human NBEAL2 gene cause gray platelet syndrome (GPS), a bleeding diathesis characterized by a lack of α granules in platelets. The functions of the NBEAL2 protein have not been explored outside platelet biology, but there are reports of increased frequency of infection and abnormal neutrophil morphology in patients with GPS. We therefore investigated the role of NBEAL2 in immunity by analyzing the phenotype of Nbeal2-deficient mice. We found profound abnormalities in the Nbeal2-deficient immune system, particularly in the function of neutrophils and NK cells. Phenotyping of Nbeal2-deficient neutrophils showed a severe reduction in granule contents across all granule subsets. Despite this, Nbeal2-deficient neutrophils had an enhanced phagocyte respiratory burst relative to Nbeal2-expressing neutrophils. This respiratory burst was associated with increased expression of cytosolic components of the NADPH oxidase complex. Nbeal2-deficient NK cells were also dysfunctional and showed reduced degranulation. These abnormalities were associated with increased susceptibility to both bacterial (Staphylococcus aureus) and viral (murine CMV) infection in vivo. These results define an essential role for NBEAL2 in mammalian immunity
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