3,397 research outputs found
Log-location-scale-log-concave distributions for survival and reliability analysis
We consider a novel sub-class of log-location-scale models for survival and reliability data formed by restricting the density of the underlying location-scale distribution to be log-concave. These models display a number of attractive properties. We particularly explore the shapes of the hazard functions of these, LLSLC, models. A relatively elegant, if partial, theory of hazard shape arises under a further minor constraint on the hazard function of the underlying log-concave distribution. Perhaps the most useful LLSLC models are contained in a class of three-parameter distributions which allow constant, increasing, decreasing, bathtub and upside-down bathtub shapes for their hazard functions
Bottom-Line Choices: Effects of Market Ideology in Florida’s Voluntary Preschool Policies
The purpose of this paper is to uncover systems of reasoning and taken-for-granted assumptions embedded within Florida’s Voluntary Preschool Education Program (VPK) policies and their implications on matters of social justice. Systems of reasoning based upon market ideology and assumptions of good economic actors, resulting from influences of conservative modernism, are identified and found to facilitate policies failing to ensure children’s constitutional right to “high quality pre-kindergarten” (Florida Constitution [Fla. Const.] art. IX, § 1(b), 2002). The authors argue that these policies intensify exclusion through institutionalized problematizing of students and act to perpetuate discriminatory and unjust practices of schooling, in this case at the preschool level. Florida’s constitution, statutes, regulations, and other government documents are analyzed to provide insight into the systems of reasoning and taken-for-granted assumptions embedded within VPK policies. Influences from conservative modernism are identified during negotiations in policy development, issues of access within the program’s choice discourses are examined, and mechanisms for exclusion embedded in these policies revealing institutional problematizing practices are analyzed. Implications for children and families historically marginalized and disempowered are discussed along with recommendations for more socially just policies and practices
Evaluation of Flying Start NHS
Introduction In January 2006 “Flying Start NHS”, a national web-based educational resource to support the transition from student to qualified practitioner for all newly qualified nurses, midwives and allied health professionals (NMAHP) joining NHS Scotland was launched. This report brings together the findings from a two-year evaluation which focussed on the impact and effectiveness of Flying Start NHS in supporting the recruitment, confidence and skills development of newly qualified nurses, midwives and allied health professionals within NHS Scotland. The evaluation was carried out be a research team from the University of the West of Scotland, the University of Stirling, and the University of Dundee
The C-Band All-Sky Survey: Instrument design, status, and first-look data
The C-Band All-Sky Survey (C-BASS) aims to produce sensitive, all-sky maps of
diffuse Galactic emission at 5 GHz in total intensity and linear polarization.
These maps will be used (with other surveys) to separate the several
astrophysical components contributing to microwave emission, and in particular
will allow an accurate map of synchrotron emission to be produced for the
subtraction of foregrounds from measurements of the polarized Cosmic Microwave
Background. We describe the design of the analog instrument, the optics of our
6.1 m dish at the Owens Valley Radio Observatory, the status of observations,
and first-look data.Comment: 10 pages, 11 figures, published in Proceedings of SPIE MIllimeter,
Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy V
(2010), Vol. 7741, 77411I-1 - 77411I-1
The radio source counts at 15 GHz and their implications for cm-wave CMB imaging
We present the preliminary results of a new survey of radio sources using the
Ryle telescope at 15.2 GHz. This is the highest frequency at which a survey has
been done that is relevant to the issue of radio source contamination in CMB
experiments. The differential source count of the 66 sources found in 63 sqdeg
is 80(S/Jy)^-2 /Jy/sr from about 20 to 500 mJy. Extrapolating this to 34 GHz
(where many cm-wave CMB experiments operate) gives an estimated temperature
contribution from sources of 9 microK in a CMB image, with a beam corresponding
to multipole l=500. A means of source subtraction is evidently necessary,
otherwise the signal-to-noise ratio in CMB images will be limited to 4 or 5,
becoming worse at higher resolution. We compare the population of sources
observed in this new survey to that predicted by extrapolation from lower
frequency surveys, finding that source fluxes, and indeed the existence of many
sources, cannot be determined by extrapolation.Comment: 4 pages, 3 figures, submitted to MNRA
Observations of Galactic star-forming regions with the Cosmic Background Imager at 31 GHz
Studies of the diffuse Galactic radio emission are interesting both for better understanding the physical conditions in our Galaxy and for minimizing the contamination in cosmological measurements. Motivated by this, we present Cosmic Background Imager 31 GHz observations of the Galactic regions NGC 6357, NGC 6334, W51 and W40 at ∼4.5 arcmin resolution and conduct an investigation of the spectral emission process in the regions at 4.5 arcmin and 1° resolution. We find that most of the emission in the regions is due to optically thin free–free. For two sub-regions of NGC 6334 and for a sub-region of W51 though, at 4.5 arcmin resolution and at 31 GHz we detect less emission than expected from extrapolation of radio data at lower frequencies assuming a spectral index of −0.12 for optically thin free–free emission, at 3.3σ, 3.7σ and 6.5σ, respectively. We also detect excess emission in a sub-region of NCG 6334 at 6.4σ, after ruling out any possible contribution from ultra-compact H II regions. At 1° resolution, we detect a spinning dust component in the spectral energy distribution of W40 that accounts for 18 ± 7 per cent of the total flux density in the region at the peak frequency of 37 GHz. Comparison with 100 μm data indicates an average dust emissivity for the sub-regions of 0.5 ± 4.4 μK(MJy sr^(−1))^(−1). Finally, we translate the excess emission in the regions to an anomalous microwave emission (AME) emissivity relative to the optical depth at 250 μm. We find that this form of emissivity is independent of the AME significance and has a value somewhere in the order of 10^4 Jy
The C-Band All-Sky Survey (C-BASS): Constraining diffuse Galactic radio emission in the North Celestial Pole region
The C-Band All-Sky Survey C-BASS is a high-sensitivity all-sky radio survey
at an angular resolution of 45 arcmin and a frequency of 4.7 GHz. We present a
total intensity 4.7 GHz map of the North Celestial Pole (NCP) region of sky,
above declination +80 deg, which is limited by source confusion at a level of
~0.6 mK rms. We apply the template-fitting (cross-correlation) technique to
WMAP and Planck data, using the C-BASS map as the synchrotron template, to
investigate the contribution of diffuse foreground emission at frequencies
~20-40 GHz. We quantify the anomalous microwave emission (AME) that is
correlated with far-infrared dust emission. The AME amplitude does not change
significantly (<10%) when using the higher frequency C-BASS 4.7 GHz template
instead of the traditional Haslam 408 MHz map as a tracer of synchrotron
radiation. We measure template coefficients of and
K per unit when using the Haslam and C-BASS synchrotron templates,
respectively. The AME contributes K rms at 22.8 GHz and accounts
for ~60% of the total foreground emission. Our results suggest that a harder
(flatter spectrum) component of synchrotron emission is not dominant at
frequencies >5 GHz; the best-fitting synchrotron temperature spectral index is
from 4.7 to 22.8 GHz and from 22.8 to
44.1 GHz. Free-free emission is weak, contributing ~K rms (~7%) at 22.8
GHz. The best explanation for the AME is still electric dipole emission from
small spinning dust grains.Comment: 18 pages, 6 figures, version matches version accepted by MNRA
C-Band All-Sky Survey: A First Look at the Galaxy
We present an analysis of the diffuse emission at 5 GHz in the first quadrant
of the Galactic plane using two months of preliminary intensity data taken with
the C-Band All Sky Survey (C-BASS) northern instrument at the Owens Valley
Radio Observatory, California. Combining C-BASS maps with ancillary data to
make temperature-temperature plots we find synchrotron spectral indices of
between 0.408 GHz and 5 GHz and between 1.420 GHz and 5 GHz for ,
. Through the subtraction of a radio recombination
line (RRL) free-free template we determine the synchrotron spectral index in
the Galactic plane () to be between
0.408 GHz and 5 GHz, with a contribution of per cent from free-free
emission at 5\,GHz. These results are consistent with previous low frequency
measurements in the Galactic plane. By including C-BASS data in spectral fits
we demonstrate the presence of anomalous microwave emission (AME) associated
with the HII complexes W43, W44 and W47 near 30 GHz, at 4.4 sigma, 3.1 sigma
and 2.5 sigma respectively. The CORNISH VLA 5 GHz source catalogue rules out
the possibility that the excess emission detected around 30\;GHz may be due to
ultra-compact HII regions. Diffuse AME was also identified at a 4 sigma level
within , between 5
GHz and 22.8 GHz.Comment: 16 pages, 9 figures, submitted to MNRAS, referee's corrections made,
awaiting for final approval for publicatio
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