2,614 research outputs found
Toothbrushing rules: power dynamics and toothbrushing in children
Dental caries is a disease of childhood social disa
dvantage being considered as a marker of family dep
rivation
and relative poverty. School-based programmes such
as, âWinning Smilesâ (WS) have been used to promote
toothbrushing with luoride toothpaste in children r
esiding in areas of high social deprivation. Withou
t a clear
understanding of the underlying toothbrushing dynam
ic how could WS achieve its deined aim to promote
toothbrushing as a self-care practice in children r
esiding in areas of greatest deprivation? The need
to research
the dynamics of childhood toothbrushing remained. T
he aim of this qualitative exploration was twofold,
irst
to explore childrenâs views of toothbrushing and se
condly, to relect, if possible, on the degree to wh
ich the
childrenâs views and experiences can aid an underst
anding of the power dynamics of toothbrushing pract
ices
in childhood. In order to achieve these aims it was
necessary to use a child-centred approach to glean
the
thoughts, values and opinions of the participating
children. The children who participated were aged b
e-
tween 8-9-years-old and resided and attended school
s in the most deprived parts of Dublin and Belfast.
The
data analysis was theoretically underpinned by the
work of Foucault and Nettleton. The children had a
series
of toothbrushing rules which were a conglomerate of
âdoâsâ and âdonâtsâ. The rules relected an element
of con
-
lict in the childrenâs behaviour since they describ
ed what the children felt they âshouldâ do (âtoothb
rushing
rulesâ), as well as what they âactuallyâ did (âtoot
hbrushing practicesâ). The toothbrushing rules were
mainly
based on their parental household rules which the c
hildren incorporated into their toothbrushing pract
ices.
It is suggested that children incorporate informati
on from parents, school-based programmes and the de
ntist
into their toothbrushing practices. This qualitativ
e exploration has allowed the process of understand
ing the
power dynamics associated with childrenâs toothbrushing t
o begin. In order to gain a greater understanding
from the childâs perspective greater time is need t
o appreciate how children incorporate what appears
to be
a rather mundane aspect of everyday life into their
health repertoire
School based health-education programmes, health-learning capacity and child oral health-related quality of life
Objective: To use a model of health learning to examine the role of health-learning capacity and the effect of a school-based oral health education intervention (Winning Smiles) on the health outcome, child oral healthârelated quality of life (COHRQoL). Setting: Primary schools, high social deprivation, Ireland/Northern Ireland. Design: Cluster randomised controlled trial. Method: A total of 383, 7- to 8-year-old children were invited to participate and randomly allocated into intervention and control conditions. Baseline and 12-month follow-up assessments of COHRQoL, self-esteem, toothbrushingâfluoride toothpaste knowledge and unstimulated saliva samples were made. An 18-hour post-brushing, saliva fluoride concentration was used to assess toothbrushing with fluoride toothpaste (behaviour). The data were entered onto SPSSv22. Structural equation modelling was applied using AMOSv22 to test for the role of health-learning capacity (baseline self-esteem and COHRQoL) and simultaneous effects of Winning Smiles upon knowledge, behaviour and COHRQoL (at follow-up). Results: A total of 238 children participated at baseline and follow-up. A partial latent hybrid model fitted the data reasonably well (Ï2â=â65.6, dfâ=â50, pâ=â.07) as shown in addition by a Comparative Fit Index of .97 and a Root Mean Square Error of Approximation (RMSEA) value of .042 (90% confidence interval [CI]: .00, .06). The intervention had a significant effect on toothbrushingâfluoride toothpaste knowledge (pâ<â.03) and an effect on COHRQoL at the 6% level (pâ<â.06). Knowledge was strongly associated with saliva fluoride concentration (pâ<â.002). Conclusion: The model of health-learning capacity assisted in explaining the effect of a school-based intervention upon knowledge, toothbrushing behaviour and tentatively on COHRQoL
H_alpha Emission from High-Velocity Clouds and their Distances
We present deep Halpha spectroscopy towards several high-velocity clouds
(HVCs) which vary in structure from compact (CHVCs) to the Magellanic Stream.
The clouds range from being bright (~640 mR) to having upper limits on the
order of 30 to 70 mR. The Halpha measurements are discussed in relation to
their HI properties and distance constraints are given to each of the complexes
based on f_esc = 6% of the ionizing photons escaping normal to the Galactic
disk (f_escs = 1 - 2% when averaged over solid angle). The results suggest that
many HVCs and CHVCs are within a ~40 kpc radius from the Galaxy and are not
members of the Local Group at megaparsec distances. However, the Magellanic
Stream is inconsistent with this model and needs to be explained. It has bright
Halpha emission and little [NII] emission and appears to fall into a different
category than the currently detected HVCs. This may reflect the lower
metallicities of the Magellanic Clouds compared to the Galaxy, but the strength
of the Halpha emission cannot be explained solely by photoionization from the
Galaxy. The interaction of the Stream with halo gas or the presence of yet
unassociated young stars may assist in ionizing the Stream.Comment: ApJ accepted, see http://casa.colorado.edu/~mputman/pubs.html for the
full resolution versio
Weighing the local dark matter with RAVE red clump stars
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 1kpc Kz/(2piG) = 68.5 pm
1.0 Msun/pc2, and (ii) at 2 kpc Kz/(2piG) = 96.9 pm 2.2 Msun/pc2. Assuming the
solar Galactic radius at R0 = 8.5 kpc, we deduce the local dark matter density
rhoDM (z=0) = 0.0143 pm 0.0011Msun pc3 = 0.542 pm 0.042 Gev/cm3 and the
baryonic surface mass density Sigma = 44.4 pm 4.1 Msun/pc2 . 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 . 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.Comment: 14 pages, 13 figures, accepted to Astronomy and Astrophysic
Identification of Globular Cluster Stars in RAVE data II: Extended tidal debris around NGC 3201
We report the identification of extended tidal debris potentially associated with the globular cluster NGC 3201, using the RAdial Velocity Experiment (RAVE) catalogue. We find the debris stars are located at a distance range of 1â7 kpc based on the forthcoming RAVE distance estimates. The derived space velocities and integrals of motion show interesting connections to NGC 3201, modulo uncertainties in the proper motions. Three stars, which are among the four most likely candidates for NGC 3201 tidal debris, are separated by 80° on the sky yet are well matched by the 12 Gyr, [Fe/H] = â1.5 isochrone appropriate for the cluster. This is the first time tidal debris around this cluster has been reported over such a large spatial extent, with implications for the cluster's origin and dynamical evolution
The disruption of nearby galaxies by the Milky Way
Interactions between galaxies are common and are an important factor in
determining their physical properties such as position along the Hubble
sequence and star-formation rate. There are many possible galaxy interaction
mechanisms, including merging, ram-pressure stripping, gas compression,
gravitational interaction and cluster tides. The relative importance of these
mechanisms is often not clear, as their strength depends on poorly known
parameters such as the density, extent and nature of the massive dark halos
that surround galaxies. A nearby example of a galaxy interaction where the
mechanism is controversial is that between our own Galaxy and two of its
neighbours -- the Large and Small Magellanic Clouds. Here we present the first
results of a new HI survey which provides a spectacular view of this
interaction. In addition to the previously known Magellanic Stream, which
trails 100 degrees behind the Clouds, the new data reveal a counter-stream
which lies in the opposite direction and leads the motion of the Clouds. This
result supports the gravitational model in which leading and trailing streams
are tidally torn from the body of the Magellanic Clouds.Comment: 17 pages with 5 figures in gif format, scheduled for publication in
the August 20th, 1998 issue of Natur
Spectroscopic signatures of extratidal stars around the globular clusters NGC 6656 (M 22), NGC 3201, and NGC 1851 from RAVE
Context. Stellar population studies of globular clusters have suggested that the brightest clusters in the Galaxy might actually be the remnant nuclei of dwarf spheroidal galaxies. If the present Galactic globular clusters formed within larger stellar systems, they are likely to be surrounded by extratidal halos and/or tails made up of stars that were tidally stripped from their parent systems. Aims. The stellar surroundings around globular clusters are therefore one of the best places to look for the remnants of an ancient dwarf galaxy. Here an attempt is made to search for tidal debris around the supernovae enriched globular clusters M? 22 and NGC 1851, as well as the kinematically unique cluster NGC 3201. Methods. The stellar parameters from the RAdial Velocity Experiment (RAVE) are used to identify stars with the RAVE metallicities, radial velocities, and elemental abundances that are consistent with the abundance patterns and properties of the stars in M? 22, NGC 1851, and NGC 3201. Results. Discovery of RAVE stars that may be associated with M? 22 and NGC 1851 are reported, some of which are at projected distances âŒ10 degrees away from the core of these clusters. Numerous RAVE stars associated with NGC 3201 suggest that either the tidal radius of this cluster is underestimated or that there are some unbound stars extending a few arc minutes from the edge of the cluster's radius. No other extratidal stars associated with NGC 3201 could be identified. The bright magnitudes of the RAVE stars make them easy targets for high-resolution follow-up observations, eventually allowing further chemical tagging to solidify (or exclude) stars outside the tidal radius of the cluster as tidal debris. In both our radial velocity histograms of the regions surrounding NGC 1851 and NGC 3201, a peak of stars at âŒ230 km? s-1 is seen, consistent with extended tidal debris from Ï Centauri
A Population of X-ray Weak Quasars: PHL 1811 Analogs at High Redshift
We report the results from Chandra and XMM-Newton observations of a sample of
10 type 1 quasars selected to have unusual UV emission-line properties (weak
and blueshifted high-ionization lines; strong UV Fe emission) similar to those
of PHL 1811, a confirmed intrinsically X-ray weak quasar. These quasars were
identified by the Sloan Digital Sky Survey at high redshift (z~2.2); eight are
radio quiet while two are radio intermediate. All of the radio-quiet PHL 1811
analogs are notably X-ray weak by a mean factor of ~13. These sources lack
broad absorption lines and have blue UV/optical continua, suggesting they are
intrinsically X-ray weak. However, their average X-ray spectrum appears to be
harder than those of typical quasars, which may indicate the presence of heavy
intrinsic X-ray absorption. Our radio-quiet PHL 1811 analogs support a
connection between an X-ray weak spectral energy distribution and PHL 1811-like
UV emission lines; this connection provides an economical way to identify X-ray
weak type 1 quasars. The fraction of radio-quiet PHL 1811 analogs in the
radio-quiet quasar population is estimated to be < 1.2%. We have investigated
correlations between relative X-ray brightness and UV emission-line properties
for a sample combining radio-quiet PHL 1811 analogs, PHL 1811, and typical type
1 quasars. These correlation analyses suggest that PHL 1811 analogs may have
extreme wind-dominated broad emission-line regions. Observationally,
radio-quiet PHL 1811 analogs appear to be a subset (~30%) of radio-quiet
weak-line quasars. The existence of a subset of quasars in which
high-ionization "shielding gas" covers most of the BELR, but little more than
the BELR, could potentially unify the PHL 1811 analogs and WLQs. The two
radio-intermediate PHL 1811 analogs are X-ray bright. One of them appears to
have jet-dominated X-ray emission, while the nature of the other remains
unclear.Comment: ApJ accepted; 25 pages, 11 figures and 8 table
Identification of globular cluster stars in RAVE data - I. Application to stellar parameter calibration
We present the identification of potential members of nearby Galactic globular clusters using radial velocities from the RAdial Velocity Experiment Data Release 4 (RAVE-DR4) survey data base. Our identifications are based on three globular clusters â NGC 3201, NGC 5139 (Ï Cen) and NGC 362 â all of which are shown to have âŁRV⣠> 100 km sâ»Âč. The high radial velocity of cluster members compared to the bulk of surrounding disc stars enables us to identify members using their measured radial velocities, supplemented by proper motion information and location relative to the tidal radius of each cluster. The identification of globular cluster stars in RAVE DR4 data offers a unique opportunity to test the precision and accuracy of the stellar parameters determined with the currently available Stellar Parameter Pipelines used in the survey, as globular clusters are ideal test-beds for the validation of stellar atmospheric parameters, abundances, distances and ages. For both NGC 3201 and Ï Cen, there is compelling evidence for numerous members (>10) in the RAVE data base; in the case of NGC 362 the evidence is more ambiguous, and there may be significant foreground and/or background contamination in our kinematically selected sample. A comparison of the RAVE-derived stellar parameters and abundances with published values for each cluster and with BASTI isochrones for ages and metallicities from the literature reveals overall good agreement, with the exception of the apparent underestimation of surface gravities for giants, in particular for the most metal-poor stars. Moreover, if the selected members are part of the main body of each cluster our results would also suggest that the distances from Binney et al., where only isochrones more metal rich than â0.9 dex were used, are typically underestimated by âŒ40âperâcent with respect to the published distances for the clusters, while the distances from Zwitter et al. show stars ranging from 1 to âŒ6.5 kpc â with indications of a trend towards higher distances at lower metallicities â for the three clusters analysed in this study
Constraining the Galaxy's dark halo with RAVE stars
We use the kinematics of giant stars that lie within kpc of the plane to measure the vertical profile of mass density near the
Sun. We find that the dark mass contained within the isodensity surface of the
dark halo that passes through the Sun
(), and the surface density within
kpc of the plane () are almost
independent of the (oblate) halo's axis ratio . If the halo is spherical, 46
per cent of the radial force on the Sun is provided by baryons, and only 4.3
per cent of the Galaxy's mass is baryonic. If the halo is flattened, the
baryons contribute even less strongly to the local radial force and to the
Galaxy's mass. The dark-matter density at the location of the Sun is
.
When combined with other literature results we find hints for a mildly oblate
dark halo with . Our value for the dark mass within the solar
radius is larger than that predicted by cosmological dark-matter-only
simulations but in good agreement with simulations once the effects of baryonic
infall are taken into account. Our mass models consist of three
double-exponential discs, an oblate bulge and a Navarro-Frenk-White dark-matter
halo, and we model the dynamics of the RAVE stars in the corresponding
gravitational fields by finding distribution functions that
depend on three action integrals. Statistical errors are completely swamped by
systematic uncertainties, the most important of which are the distance to the
stars in the photometric and spectroscopic samples and the solar distance to
the Galactic centre. Systematics other than the flattening of the dark halo
yield overall uncertainties per cent.Comment: 20 pages, 17 figures, accepted for publication in MNRA
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