535 research outputs found
Canonical Generations and the British Left: The Narrative Construction of the Minersâ Strike 1984â85
âGenerationsâ have been invoked to describe a variety of social and cultural relationships, and to understand the development of self-conscious group identity. Equally, the term can be an applied label and politically useful construct; generations can be retrospectively produced. Drawing on the concept of âcanonical generationsâ â those whose experiences come to epitomise an event of historic and symbolic importance â this article examines the narrative creation and functions of âgenerationsâ as collective memory shapes and re-shapes the desire for social change. Building a case study of the canonical role of the minersâ strike of 1984â85 in the narrative history of the British left, it examines the selective appropriation and transmission of the past in the development of political consciousness. It foregrounds the autobiographical narratives of activists who, in examining and legitimising their own actions and prospects, (re)produce a âgenerationâ in order to create a relatable and useful historical understanding
The Distance and Metallicity of the Newly Discovered, Nearby Irregular Galaxy HIZSS3
HIZSS3 is an H I source in the Zone of Avoidance. Its radio characteristics
are consistent with it being nearby (~ 1.8 Mpc) low-mass dwarf irregular (dIm)
galaxy. It contains a modest H II region, but its stellar population has not
been resolved by optical observations. MMT spectra of the H II region are used
to derive the line-of-sight extinction (E(B-V) = 1.41 +/- 0.04) and gas
metallicity (log O/H + 12 ~ 7.8). ESO VLT near-IR images clearly reveal a
resolved stellar population. Narrow-band Pbeta images of the H II region are
used in combination with previously published Halpha data to obtain an
independent line-of-sight extinction estimate: E(B-V) = 1.32 +/- 0.04. The
adopted foreground extinction is E(B-V) = 1.36 +/- 0.06. Based on the K-band
luminosity function and K,J-K color-magnitude diagram, the apparent magnitude
and color of the tip of the red-giant branch (TRGB) are derived. In turn, these
parameters are combined with the adopted foreground extinction to estimate the
distance (1.69 +/- 0.07 Mpc) and mean red giant branch metallicity ([Fe/H] =
-0.5 +/- 0.1). As an ensemble, these new observations significantly strengthen
the conclusion that HIZSS3 is a newly discovered low-mass dIm lurking behind
the Milky Way in the outskirts of the Local Group.Comment: Accepted, scheduled for ApJ, 10 Apr 05, V623 ; 14 page
The Canada-UK Deep Submillimetre Survey: First Submillimetre Images, the Source Counts, and Resolution of the Background
We present the first results of a deep unbiased submillimetre survey carried
out at 450 and 850 microns. We detected 12 sources at 850 microns, giving a
surface density of sources with 850-micron flux densities > 2.8mJy of of
0.49+-0.16 per square arcmin. The sources constitute 20-30% of the background
radiation at 850 microns and thus a significant fraction of the entire
background radiation produced by stars. This implies, through the connection
between metallicity and background radiation, that a significant fraction of
all the stars that have ever been formed were formed in objects like those
detected here. The combination of their large contribution to the background
radiation and their extreme bolometric luminosities make these objects
excellent candidates for being proto-ellipticals. Optical astronomers have
recently shown that the UV-luminosity density of the universe increases by a
factor of about 10 between z=0 and z=1 and then decreases again at higher
redshifts. Using the results of a parallel submillimetre survey of the local
universe, we show that both the submillimetre source density and background can
be explained if the submillimetre luminosity density evolves in a similar way
to the UV-luminosity density. Thus, if these sources are ellipticals in the
process of formation, they may be forming at relatively modest redshifts.Comment: 8 pages (LATEX), 6 postscript figures, submitted to ApJ Letter
X-Rays from NGC 3256: High-Energy Emission in Starburst Galaxies and Their Contribution to the Cosmic X-Ray Background
The infrared-luminous galaxy NGC3256 is a classic example of a merger induced
nuclear starburst system. We find here that it is the most X-ray luminous
star-forming galaxy yet detected (~10^42 ergs/s). Long-slit optical
spectroscopy and a deep, high-resolution ROSAT X-ray image show that the
starburst is driving a "superwind" which accounts for ~20% of the observed soft
(kT~0.3 keV) X-ray emission. Our model for the broadband X-ray emission of
NGC3256 contains two additional components: a warm thermal plasma (kT~0.8 keV)
associated with the central starburst, and a hard power-law component with an
energy index of ~0.7. We find that the input of mechanical energy from the
starburst is more than sufficient to sustain the observed level of emission. We
also examine possible origins for the power-law component, concluding that
neither a buried AGN nor the expected population of high-mass X-ray binaries
can account for this emission. Inverse-Compton scattering, involving the
galaxy's copious flux of infrared photons and the relativistic electrons
produced by supernovae, is likely to make a substantial contribution to the
hard X-ray flux. Such a model is consistent with the observed radio and IR
fluxes and the radio and X-ray spectral indices. We explore the role of
X-ray-luminous starbursts in the production of the cosmic X-ray background
radiation. The number counts and spectral index distribution of the faint radio
source population, thought to be dominated by star-forming galaxies, suggest
that a significant fraction of the hard X-ray background could arise from
starbursts at moderate redshift.Comment: 31 pages (tex, epsf), 8 figures (postscript files), accepted for
publication in Part 1 of The Astrophysical Journa
The Canada-UK Deep Submillimetre Survey: The Survey of the 14-hour field
We have used SCUBA to survey an area of 50 square arcmin, detecting 19
sources down to a 3sigma sensitivity limit of 3.5 mJy at 850 microns. We have
used Monte-Carlo simulations to assess the effect of source confusion and noise
on the SCUBA fluxes and positions, finding that the fluxes of sources in the
SCUBA surveys are significantly biased upwards and that the fraction of the 850
micron background that has been resolved by SCUBA has been overestimated. The
radio/submillmetre flux ratios imply that the dust in these galaxies is being
heated by young stars rather than AGN. We have used simple evolution models
based on our parallel SCUBA survey of the local universe to address the major
questions about the SCUBA sources: (1) what fraction of the star formation at
high redshift is hidden by dust? (2) Does the submillimetre luminosity density
reach a maximum at some redshift? (3) If the SCUBA sources are
proto-ellipticals, when exactly did ellipticals form? However, we show that the
observations are not yet good enough for definitive answers to these questions.
There are, for example, acceptable models in which 10 times as much
high-redshift star formation is hidden by dust as is seen at optical
wavelengths, but also acceptable ones in which the amount of hidden star
formation is less than that seen optically. There are acceptable models in
which very little star formation occurred before a redshift of three (as might
be expected in models of hierarchical galaxy formation), but also ones in which
30% of the stars have formed by this redshift. The key to answering these
questions are measurements of the dust temperatures and redshifts of the SCUBA
sources.Comment: 41 pages (latex), 17 postscript figures, to appear in the November
issue of the Astronomical Journa
The Origin of the Mass--Metallicity Relation: Insights from 53,000 Star-Forming Galaxies in the SDSS
We utilize Sloan Digital Sky Survey imaging and spectroscopy of ~53,000
star-forming galaxies at z~0.1 to study the relation between stellar mass and
gas-phase metallicity. We derive gas-phase oxygen abundances and stellar masses
using new techniques which make use of the latest stellar evolutionary
synthesis and photoionization models. We find a tight (+/-0.1 dex) correlation
between stellar mass and metallicity spanning over 3 orders of magnitude in
stellar mass and a factor of 10 in metallicity. The relation is relatively
steep from 10^{8.5} - 10^{10.5} M_sun, in good accord with known trends between
luminosity and metallicity, but flattens above 10^{10.5} M_sun. We use indirect
estimates of the gas mass based on the H-alpha luminosity to compare our data
to predictions from simple closed box chemical evolution models. We show that
metal loss is strongly anti-correlated with baryonic mass, with low mass dwarf
galaxies being 5 times more metal-depleted than L* galaxies at z~0.1. Evidence
for metal depletion is not confined to dwarf galaxies, but is found in galaxies
with masses as high as 10^{10} M_sun. We interpret this as strong evidence both
of the ubiquity of galactic winds and of their effectiveness in removing metals
from galaxy potential wells.Comment: ApJ accepted, 15 pages, 9 figures, emulateapj.st
The TRUST Principles for digital repositories.
As information and communication technology has become pervasive in our society, we are increasingly dependent on both digital data and repositories that provide access to and enable the use of such resources. Repositories must earn the trust of the communities they intend to serve and demonstrate that they are reliable and capable of appropriately managing the data they hold.
Following a year-long public discussion and building on existing community consensus1, several stakeholders, representing various segments of the digital repository community, have collaboratively developed and endorsed a set of guiding principles to demonstrate digital repository trustworthiness. Transparency, Responsibility, User focus, Sustainability and Technology: the TRUST Principles provide a common framework to facilitate discussion and implementation of best practice in digital preservation by all stakeholders.Proyecto de Enlace de Biblioteca
The validity of using ICD-9 codes and pharmacy records to identify patients with chronic obstructive pulmonary disease
Background: Administrative data is often used to identify patients with chronic obstructive pulmonary disease (COPD), yet the validity of this approach is unclear. We sought to develop a predictive model utilizing administrative data to accurately identify patients with COPD.
Methods: Sequential logistic regression models were constructed using 9573 patients with postbronchodilator spirometry at two Veterans Affairs medical centers (2003-2007). COPD was defined as: 1) FEV1/FVC <0.70, and 2) FEV1/FVC < lower limits of normal. Model inputs included age, outpatient or inpatient COPD-related ICD-9 codes, and the number of metered does inhalers (MDI) prescribed over the one year prior to and one year post spirometry. Model performance was assessed using standard criteria.
Results: 4564 of 9573 patients (47.7%) had an FEV1/FVC < 0.70. The presence of â„1 outpatient COPD visit had a sensitivity of 76% and specificity of 67%; the AUC was 0.75 (95% CI 0.74-0.76). Adding the use of albuterol MDI increased the AUC of this model to 0.76 (95% CI 0.75-0.77) while the addition of ipratropium bromide MDI increased the AUC to 0.77 (95% CI 0.76-0.78). The best performing model included: â„6 albuterol MDI, â„3 ipratropium MDI, â„1 outpatient ICD-9 code, â„1 inpatient ICD-9 code, and age, achieving an AUC of 0.79 (95% CI 0.78-0.80).
Conclusion: Commonly used definitions of COPD in observational studies misclassify the majority of patients as having COPD. Using multiple diagnostic codes in combination with pharmacy data improves the ability to accurately identify patients with COPD.Department of Veterans Affairs, Health Services Research and Development (DHA), American Lung Association (CI- 51755-N) awarded to DHA, the American Thoracic Society Fellow Career Development AwardPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/84155/1/Cooke - ICD9 validity in COPD.pd
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