831 research outputs found
Are the Luminosities of RR Lyrae Stars Affected by Second Parameter Effects?
There is a serious discrepancy between the distance to the LMC derived from
the Cepheid Period-Luminosity relation and that obtained by using the Galactic
calibration for the luminosity of RR Lyrae stars. It is suggested that this
problem might be due to the fact that second parameter effects make it
inappropriate to apply Galactic calibrations to RR Lyrae variables in the
Magellanic Clouds, i.e. Mv(RR) could depend on both [Fe/H] and on one or more
second parameters.Comment: 10 pages as uuencoded compressed Postscript. Also available at
http://www.dao.nrc.ca/DAO/SCIENCE/science.htm
The accuracy of a point-of-care test among different operators using the QBC Autoread Plus Analyzer for the measurement of a basic full blood count
Background. Major issues around the implementation of point-of-care testing (POCT) include: user type, regulatory control, ongoing quality monitoring and limited guideline adherence.59 December 2019, Print editionObjectives. To determine if there are significant differences in the results of a POC full blood count test between different levels of healthcare and non-medical ‘lay’ users compared with laboratory users (technologists/pathologists).Methods. This article retrospectively reviews the technical evaluation database of the intensive care unit (ICU), Chris Hani Baragwanath Academic Hospital, Johannesburg, South Africa. We searched for samples analysed by doctors, clerks and laboratory personnel. A minimum number of 60 comparisons were required. Bland-Altman plots, Spearman’s correlation and Passing-Bablok fit were used to analyse the dataset.Results. There were 72 comparisons for haematocrit (Hct), 98 for white cell count (WCC) and 137 for platelets (Plt) between the clerk and laboratory personnel. The correlations were 0.91, 0.96 and 0.92, respectively. All were statistically significant. Using the Bland-Altman method, there was good agreement between results of the clerk and those of the laboratory staff, with a mean bias of 0.5% (Hct), 0.1 × 109/L (WCC) and 10 × 109/L (Plt). An insufficient number of tests were performed by medical doctors for statistical comparison.Conclusions. With appropriate training, non-medical, non-healthcare lay users are able to perform a moderately complex POCT with similar accuracy as trained laboratory professionals. The focus should shift to equipment and quality management processes rather than the medical/technical qualification of the user
The Increase in Intergenerational African American Families Headed by Grandmothers
This article analyzes census data on grandparent heads of household. Information on African American grandparents, grandmothers in particular, is the focus of this analysis. The data include a profile of African American grandparent householders, reasons for the increase in households headed by grandparents, challenges and problems, living arrangements/household characteristics, and implications for practice. African American children are more likely to live in the home of their grandparents than are White or Hispanic children. In 1993, 12 percent of African American children lived in the home of their grandparent in comparison to 4 percent for Whites and 6 percent for Hispanics. The increased complexity of intergenerational households, along with a variety of social problems, suggest that new strategies must be developed to help these families cope
Galactic abundance gradients from Cepheids : On the iron abundance gradient around 10-12 kpc
Context: Classical Cepheids can be adopted to trace the chemical evolution of
the Galactic disk since their distances can be estimated with very high
accuracy. Aims: Homogeneous iron abundance measurements for 33 Galactic
Cepheids located in the outer disk together with accurate distance
determinations based on near-infrared photometry are adopted to constrain the
Galactic iron gradient beyond 10 kpc. Methods: Iron abundances were determined
using high resolution Cepheid spectra collected with three different
observational instruments: ESPaDOnS@CFHT, Narval@TBL and [email protected] ESO/MPG
telescope. Cepheid distances were estimated using near-infrared (J,H,K-band)
period-luminosity relations and data from SAAO and the 2MASS catalog. Results:
The least squares solution over the entire data set indicates that the iron
gradient in the Galactic disk presents a slope of -0.052+/-0.003 dex/kpc in the
5-17 kpc range. However, the change of the iron abundance across the disk seems
to be better described by a linear regime inside the solar circle and a
flattening of the gradient toward the outer disk (beyond 10 kpc). In the latter
region the iron gradient presents a shallower slope, i.e. -0.012+/-0.014
dex/kpc. In the outer disk (10-12 kpc) we also found that Cepheids present an
increase in the spread in iron abundance. Current evidence indicates that the
spread in metallicity depends on the Galactocentric longitude. Finally, current
data do not support the hypothesis of a discontinuity in the iron gradient at
Galactocentric distances of 10-12 kpc. Conclusions: The occurrence of a spread
in iron abundance as a function of the Galactocentric longitude indicates that
linear radial gradients should be cautiously treated to constrain the chemical
evolution across the disk.Comment: 5 tables, 8 figures, Accepted in A&
Cepheid Period-Radius and Period-Luminosity Relations and the Distance to the LMC
We have used the infrared Barnes-Evans surface brightness technique to derive
the radii and distances of 34 Galactic Cepheid variables. Radius and distance
results obtained from both versions of the technique are in excellent
agreement. The radii of 28 variables are used to determine the period-radius
relation. This relation is found to have a smaller dispersion than in previous
studies, and is identical to the period-radius relation found by Laney & Stobie
from a completely independent method, a fact which provides persuasive evidence
that the Cepheid period-radius relation is now determined at a very high
confidence level. We use the accurate infrared distances to determine
period-luminosity relations in the V, I, J, H and K passbands from the Galactic
sample of Cepheids. We derive improved slopes of these relations from updated
LMC Cepheid samples and adopt these slopes to obtain accurate absolute
calibrations of the PL relation. By comparing these relations to the ones
defined by the LMC Cepheids, we derive strikingly consistent and precise values
for the LMC distance modulus in each of the passbands which yield a mean value
of DM (LMC) = 18.46 +- 0.02.
Our results show that the infrared Barnes-Evans technique is very insensitive
to both Cepheid metallicity and adopted reddening, and therefore a very
powerful tool to derive accurate distances to nearby galaxies by a direct
application of the technique to their Cepheid variables, rather than by
comparing PL relations of different galaxies, which introduces much more
sensitivity to metallicity and absorption corrections which are usually
difficult to determine.Comment: LaTeX, AASTeX style, 9 Figures, 10 Tables, The Astrophysical Journal
in press (accepted Oct. 14, 1997). Fig. 3 replace
Applying implementation science to improve care for familial hypercholesterolemia
PURPOSE OF REVIEW: Improving care of individuals with familial hypercholesteremia (FH) is reliant on the synthesis of evidence-based guidelines and their subsequent implementation into clinical care. This review describes implementation strategies, defined as methods to improve translation of evidence into FH care, that have been mapped to strategies from the Expert Recommendations for Implementing Change (ERIC) compilation.
RECENT FINDINGS: A search using the term \u27familial hypercholesterolemia\u27 returned 1350 articles from November 2018 to July 2021. Among these, there were 153 articles related to improving FH care; 1156 were excluded and the remaining 37 were mapped to the ERIC compilation of strategies: assess for readiness and identify barriers and facilitators [9], develop and organize quality monitoring systems [14], create new clinical teams [2], facilitate relay of clinical data to providers [4], and involve patients and family members [8]. There were only 8 of 37 studies that utilized an implementation science theory, model, or framework and two that explicitly addressed health disparities or equity.
SUMMARY: The mapping of the studies to implementation strategies from the ERIC compilation provides a framework for organizing current strategies to improve FH care. This study identifies potential areas for the development of implementation strategies to target unaddressed aspects of FH care
The mysterious eruption of V838 Mon
V838 Mon is marking one of the most mysterious stellar outbursts on record.
The spectral energy distribution of the progenitor resembles an under-luminous
F main sequence star (at V=15.6 mag), that erupted into a cool supergiant
following a complex and multi-maxima lightcurve (peaking at V=6.7 mag). The
outburst spectrum show BaII, LiI and lines of several s-elements, with wide
P-Cyg profiles and a moderate and retracing emission in the Balmer lines. A
light-echo discovered expanding around the object helped to constrain the
distance (d=790+/-30 pc), providing M_V=+4.45 in quiescence and M_V=-4.35 at
optical maximum (somewhat dependent on the still uncertain E(B-V)=0.5
reddening). The general outburst trend is toward lower temperatures and larger
luminosities, and continuing so at the time of writing. The object properties
conflict with a classification within already existing categories: the
progenitor was not on a post-AGB track and thus the similarities with the
born-again AGB stars FG Sge, V605 Aql and Sakurai's object are limited to the
cool giant spectrum at maximum; the cool spectrum, the moderate wind velocity
(500 km/sec and progressively reducing) and the monotonic decreasing of the low
ionization condition argues against a classical nova scenario. The closest
similarity is with a star that erupted into an M-type supergiant discovered in
M31 by Rich et al. (1989), that became however much brighter by peaking at
M_V=-9.95, and with V4332 Sgr that too erupted into an M-type giant (Martini et
al. 1999) and that attained a lower luminosity, closer to that of V838 Mon.
M31-RedVar, V4332 Sgr and V838 Mon could be manifestations of the same and new
class of astronomical objects.Comment: A&A, in pres
Life at GrandFamilies House: The First Six Months
Recent reports cite estimates of more than two million children in the United States who are currently living in kinship care arrangements; 10% or approximately 200,000 of these relationships are children in foster care. Much kinship care is done by midlife and older persons who are finding themselves assuming new responsibilities associated with parenting their grandchildren, typically for a period of two years or more. This is a social phenomenon that cuts across all socioeconomic, racial, and ethnic groups. There are many challenges facing these nontraditional families including healthcare, income security, education, social support, and housing. Public and private partnerships are beginning to take shape to respond to some of these challenges. This report describes the first six months of one initiative that was undertaken in Massachusetts to begin to address the need for supportive housing
Rebuilding the Cepheid Distance Scale I: A Global Analysis of Cepheid Mean Magnitudes
We develop a statistical method for using multicolor photometry to determine
distances using Cepheid variables including the effects of temperature,
extinction, and metallicity and apply it to UBVRIJHK photometry of 694 Cepheids
in 17 galaxies. We derive homogeneous distance, extinction and uncertainty
estimates for four models, starting from the standard extragalactic method and
then adding the physical effects of temperature distributions, extinction
distributions, requiring positive definite extinctions, and metallicity. While
we find general agreement with published distances when we make similar
systematic assumptions, there is a clear problem in the standard distances
because they require Cepheids with negative extinctions, particularly in low
metallicity galaxies, unless the mean LMC extinction exceeds E(B-V) > 0.25. The
problem can be explained by the physically expected metallicity dependence of
the Cepheid distance scale, where metal-poor Cepheids are hotter and fainter
than metal-rich Cepheids. For V and I we found that the mean magnitude change
is -0.14 +/- 0.14 mag/dex and the mean color change is 0.13 +/- 0.04 mag/dex,
with the change in color dominating the change in distance. The effect on Type
Ia supernova estimates of the Hubble constant is dramatic because most were
found in the metal poor galaxies with the bluest Cepheids. The Type Ia
Multi-color Light Curve Shape (MLCS) method estimate for H_0 formally rises
from 69 +/- 8 km/s Mpc to 80 +/- 6 km/s Mpc with the metallicity correction.Comment: 54 pages, 7 figures, 4 tables, submitted to Ap
On the metallicity distribution of classical Cepheids in the Galactic inner disk
We present homogeneous and accurate iron abundances for almost four dozen
(47) of Galactic Cepheids using high-spectral resolution (R40,000) high
signal-to-noise ratio (S/N 100) optical spectra collected with UVES at
VLT. A significant fraction of the sample (32) is located in the inner disk (RG
6.9 kpc) and for half of them we provide new iron abundances. Current
findings indicate a steady increase in iron abundance when approaching the
innermost regions of the thin disk. The metallicity is super-solar and ranges
from 0.2 dex for RG 6.5 kpc to 0.4 dex for RG 5.5 kpc. Moreover,
we do not find evidence of correlation between iron abundance and distance from
the Galactic plane. We collected similar data available in the literature and
ended up with a sample of 420 Cepheids. Current data suggest that the mean
metallicity and the metallicity dispersion in the four quadrants of the
Galactic disk attain similar values. The first-second quadrants show a more
extended metal-poor tail, while the third-fourth quadrants show a more extended
metal-rich tail, but the bulk of the sample is at solar iron abundance.
Finally, we found a significant difference between the iron abundance of
Cepheids located close to the edge of the inner disk ([Fe/H]0.4) and
young stars located either along the Galactic bar or in the nuclear bulge
([Fe/H]0). Thus suggesting that the above regions have had different
chemical enrichment histories. The same outcome applies to the metallicity
gradient of the Galactic bulge, since mounting empirical evidence indicates
that the mean metallicity increases when moving from the outer to the inner
bulge regions.Comment: 10 pages, 5 figures; Corrected typos, corrected Table
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