Using a sample of 213 713 stars from the Radial Velocity Experiment (RAVE) survey, limited to a distance of 2 kpc from the Sun and to |z| < 1 kpc, we report the detection of a velocity gradient of ...disc stars in the fourth quadrant, directed radially from the Galactic Centre. In the direction of the Galactic Centre, we apply a simple method independent of stellar proper motions and of Galactic parameters to assess the existence of this gradient in the RAVE data. This velocity gradient corresponds to |K+C| > rsim 3 km s−1 kpc−1, where K and C are the Oort constants measuring the local divergence and radial shear of the velocity field, respectively. In order to illustrate the effect, assuming a zero radial velocity of the local standard of rest we then reconstruct the two-dimensional Galactocentric velocity maps using two different sets of proper motions and photometric distances based either on isochrone fitting or on K-band magnitudes, and considering two sets of values for the Galactocentric radius of the Sun and local circular speed. Further observational confirmation of our finding with line-of-sight velocities of stars at low latitudes, together with further modelling, should help constrain the non-axisymmetric components of the Galactic potential, including the bar, the spiral arms and possibly the ellipticity of the dark halo.
In the thick of it: metal-poor disc stars in RAVE Kordopatis, G.; Gilmore, G.; Wyse, R. F. G. ...
Monthly Notices of the Royal Astronomical Society,
12/2013, Letnik:
436, Številka:
4
Journal Article
Recenzirano
Odprti dostop
By selecting in the Radial Velocity Experiment-fourth data release (RAVE-DR4) survey the stars located between 1 and 2 kpc above the Galactic plane, we question the consistency of the simplest ...three-component model (thin disc, thick disc and halo) for the Milky Way. We confirm that the metallicity and azimuthal velocity distribution functions of the thick disc are not Gaussian. In particular, we find that the thick disc has an extended metallicity tail going at least down to M/H = -2 dex, contributing roughly 3 per cent of the entire thick disc population and having a shorter scalelength compared to the canonical thick disc. The mean azimuthal velocity of these metal-poor stars allows us to estimate the correlation between the metallicity (M/H) and the orbital velocity (V...), which is an important constraint on the formation mechanisms of the Galactic thick disc. Given our simple approach, we find ... 50 km s... dex..., which is in very good agreement with previous literature values. We complete the study with a brief discussion on the implications of the formation scenarios for the thick disc and suggest that given the above-mentioned characteristics, a thick disc mainly formed by radial migration mechanisms seems unlikely. (ProQuest: ... denotes formulae/symbols omitted.)
Toybox is a kindergarten-based intervention program that targets sedentary behavior, snacking and drinking habits, as well as promoting physical activity in an effort to improve healthy energy ...balance-related behaviors among children attending kindergartens in Malaysia. The pilot of this program was conducted as a randomized controlled trial (RCT) involving 837 children from 22 intervention kindergartens and 26 control kindergartens respectively. This paper outlines the process evaluation of this intervention.
We assessed five process indicators: recruitment, retention, dosage, fidelity, and satisfaction for the Toybox program. Data collection was conducted via teachers' monthly logbooks, post-intervention feedback through questionnaires, and focus group discussions (FGD) with teachers, parents, and children. Data were analyzed using quantitative and qualitative data analysis methods.
A total of 1072 children were invited. Out of the 1001 children whose parents consented to join, only 837 completed the program (Retention rate: 88.4%). As high as 91% of the 44 teachers and their assistants engaged positively in one or more of the process evaluation data collection methods. In terms of dosage and fidelity, 76% of parents had received newsletters, tip cards, and posters at the appropriate times. All teachers and their assistants felt satisfied with the intervention program. However, they also mentioned some barriers to its implementation, including the lack of suitable indoor environments to conduct activities and the need to make kangaroo stories more interesting to captivate the children's attention. As for parents, 88% of them were satisfied with the family-based activities and enjoyed them. They also felt that the materials provided were easy to understand and managed to improve their knowledge. Lastly, the children showed positive behaviors in consuming more water, fruits, and vegetables.
The Toybox program was deemed acceptable and feasible to implement by the parents and teachers. However, several factors need to be improved before it can be expanded and embedded as a routine practice across Malaysia.
We determine the Galactic potential in the solar neigbourhood from RAVE observations. We select red clump stars for which accurate distances, radial velocities, and metallicities have been measured. ...Combined with data from the 2MASS and UCAC catalogues, we build a sample of ~4600 red clump stars within a cylinder of 500 pc radius oriented in the direction of the South Galactic Pole, in the range of 200 pc to 2000 pc distances. We deduce the vertical force and the total mass density distribution up to 2 kpc away from the Galactic plane by fitting a distribution function depending explicitly on three isolating integrals of the motion in a separable potential locally representing the Galactic one with four free parameters. Because of the deep extension of our sample, we can determine nearly independently the dark matter mass density and the baryonic disc surface mass density. We find (i) at 1 kpc Kz/ (2πG) = 68.5 ± 1.0 M⊙ pc-2; and (ii) at 2 kpc Kz/ (2πG) = 96.9 ± 2.2 M⊙ pc-2. Assuming the solar Galactic radius at R0 = 8.5 kpc, we deduce the local dark matter density ρDM(z = 0) = 0.0143 ± 0.0011 M⊙pc-3 = 0.542 ± 0.042 Gev cm-3 and the baryonic surface mass density Σbar = 44.4 ± 4.1 M⊙pc-2. Our results are in agreement with previously published Kz determinations up to 1 kpc, while the extension to 2 kpc shows some evidence for an unexpectedly large amount of dark matter. A flattening of the dark halo of order 0.8 can produce such a high local density in combination with a circular velocity of 240 km s-1. It could also be consistent with a spherical cored dark matter profile whose density does not drop sharply with radius. Another explanation, allowing for a lower circular velocity, could be the presence of a secondary dark component, a very thick disc resulting either from the deposit of dark matter from the accretion of multiple small dwarf galaxies, or from the presence of an effective “phantom” thick disc in the context of effective galactic-scale modifications of gravity.
ABSTRACT
Ultra-faint dwarf galaxies (UFDs) are among the oldest and most metal-poor galaxies in the cosmos, observed to contain no gas and a high dark matter mass fraction. Understanding the chemical ...abundance dispersion in such extreme environments could shed light on the very first generations of stars. We present a novel inhomogeneous chemical evolution model, i-getool, that we apply to two UFDs, Carina II and Reticulum II, both satellites of the Large Magellanic Cloud. Our model is based on the Monte Carlo sampling of the initial mass function as star formation proceeds in different gas cells of the galaxy volume. We account for the chemical enrichment of supernova (SN) bubbles as they spread in the interstellar medium, causing dispersion in the elemental abundances. We recreate the abundance patterns of α- and odd-Z elements, predicting two sequences in C/Fe and N/Fe at all metallicities. Our models underestimate C/Fe and Ti/Fe because of the large uncertainty in the adopted stellar nucleosynthesis yields. We discuss that the observed C and N abundances had likely been affected by internal mixing processes, which changed the initial surface abundances in the red giants. Our SN feedback scheme is responsible for driving galactic outflows, which quench the star formation activity at early times. We predict an average outflow mass-loading factor ≈103, which extrapolates towards very low galaxy stellar masses the trend observed at high masses. Finally, by combining our model with the MIST isochrone database, we compare our synthetic colour–magnitude diagrams to observations.
We investigate the kinematic parameters of the Milky Way disk using the Radial Velocity Experiment (RAVE) and Geneva-Copenhagen Survey (GCS) stellar surveys. We do this by fitting a kinematic model ...to the data and taking the selection function of the data into account. The large size of the RAVE survey allows us to get precise values for most parameters. Using a simple model for vertical dependence of kinematics, we find that it is possible to match the Sgr A* proper motion without any need for V being larger than that estimated locally by surveys like GCS.
We describe our new ‘mlapm halo finder’ (mhf), which is based on the adaptive grid structure of the N-body code mlapm. We then extend the mhf code in order to track the orbital evolution of ...gravitationally bound objects through any given cosmological N-body simulation – our so-called ‘mlapm halo tracker’ (mht). The mode of operation of mht is demonstrated using a series of eight high-resolution N-body simulations of galaxy clusters. Each of these haloes hosts more than one million particles within their virial radii rvir. We use mht as well as mhf to follow the temporal evolution of hundreds of individual satellites, and show that the radial distribution of these substructure satellites follows a ‘universal’ radial distribution irrespective of the environment and formation history of the host halo. This in fact might pose another problem for simulations of cold dark matter structure formation, as there are recent findings by Taylor, Silk & Babul that the Milky Way satellites are found preferentially closer to the Galactic Centre and simulations underestimate the amount of central substructure. Further, this universal substructure profile is anti-biased with respect to the underlying dark matter profile. The halo finder mhf will become part of the open source mlapm distribution.
Abstract
Background
Patients admitted with age 60 years and over with a hip fracture admitted to a District General Hospital.
Introduction
The aim was to improve the prescribing of regular laxatives ...and analgesia at the time of admission to hospital.
Methods
There were repeated PDSA cycles. Data was collected on consecutive patients (by admission date) identified from the National Hip Fracture Database. Data was collected at baseline (10 patients in November 2013) and after Phase 1 intervention (20 patients, December 2013—January 2014), after Phase 2 (20 patients, February 2014), after Phase 3 (39 patients, April—June 2017) and after Phase 4 (September—October 2020). The interventions were as follows: Phase 1: Prompts at new doctor induction (‘Induction’) + prompts in hip fracture admission document. Phase2: Phase 1 intervention + flow diagram in fracture admission document. Phase 3: Prompts at Induction + electronic prescribing protocol (including laxatives and analgesics) + removal of flow diagram from admission document. Phase 4: Phase 3 intervention + more effort to explain to new locum doctors.
Results
Laxative prescribing: Baseline = 40%, Phase 1 = 80%, Phase 2 = 80%, Phase 3 = 56%, Phase 4 = 74% (24 hours post-admission = 90%). Paracetamol prescribing: Baseline 100%, Phase 1,100%, Phase 2,100%, Phase 3 64%, Phase 4 82% (24 h post-admission = 90%). Regular strong opioid prescribing: Admission: Baseline 60%, Phase 1 90%, Phase 2,100%, Phase 3 44%, Phase 4 80% (24 h post-admission = 90%).
Conclusion
1. Orthopaedic Surgeons can prescribe laxatives and analgesia well—given sufficient prompts 2. The electronic solution is not always sufficient—locum doctors may not be aware of it. 3. Do not assume continued success Future Plans Re-introduce flow diagram to admission document. Acknowledgements Many people have helped with previous phases & will be acknowledged.
Abstract
We examine the chemical properties of five cosmological hydrodynamical simulations of an M33-like disc galaxy which have been shown previously to be consistent with the morphological ...characteristics and bulk scaling relations expected of late-type spirals. These simulations are part of the Making Galaxies in a Cosmological Context Project, in which stellar feedback is tuned to match the stellar mass-halo mass relationship. Each realization employed identical initial conditions and assembly histories, but differed from one another in their underlying baryonic physics prescriptions, including (a) the efficiency with which each supernova energy couples to the surrounding interstellar medium, (b) the impact of feedback associated with massive star radiation pressure, (c) the role of the minimum shut-off time for radiative cooling of Type II supernovae remnants, (d) the treatment of metal diffusion and (e) varying the initial mass function. Our analysis focusses on the resulting stellar metallicity distribution functions (MDFs) in each simulated (analogous) 'solar neighbourhood' (2-3 disc scalelengths from the galactic centre) and central 'bulge' region. We compare and contrast the simulated MDFs' skewness, kurtosis and dispersion (inter-quartile, inter-decile, inter-centile and inter-tenth-percentile regions) with that of the empirical solar neighbourhood MDF and Local Group dwarf galxies. We find that the MDFs of the simulated discs are more negatively skewed, with higher kurtosis, than those observed locally in the Milky Way and Local Group dwarfs. We can trace this difference to the simulations' very tight and correlated age-metallicity relations (compared with that of the Milky Way's solar neighbourhood), suggesting that these relations within 'dwarf' discs might be steeper than in L
★ discs (consistent with the simulations' star formation histories and extant empirical data), and/or the degree of stellar orbital redistribution and migration inferred locally has not been captured in their entirety, at the resolution of our simulations. The important role of metal diffusion in ameliorating the overproduction of extremely metal-poor stars is highlighted.
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