154 research outputs found
Testing the Hubble Law with the IRAS 1.2 Jy Redshift Survey
We test and reject the claim of Segal et al. (1993) that the correlation of
redshifts and flux densities in a complete sample of IRAS galaxies favors a
quadratic redshift-distance relation over the linear Hubble law. This is done,
in effect, by treating the entire galaxy luminosity function as derived from
the 60 micron 1.2 Jy IRAS redshift survey of Fisher et al. (1995) as a distance
indicator; equivalently, we compare the flux density distribution of galaxies
as a function of redshift with predictions under different redshift-distance
cosmologies, under the assumption of a universal luminosity function. This
method does not assume a uniform distribution of galaxies in space. We find
that this test has rather weak discriminatory power, as argued by Petrosian
(1993), and the differences between models are not as stark as one might expect
a priori. Even so, we find that the Hubble law is indeed more strongly
supported by the analysis than is the quadratic redshift-distance relation. We
identify a bias in the the Segal et al. determination of the luminosity
function, which could lead one to mistakenly favor the quadratic
redshift-distance law. We also present several complementary analyses of the
density field of the sample; the galaxy density field is found to be close to
homogeneous on large scales if the Hubble law is assumed, while this is not the
case with the quadratic redshift-distance relation.Comment: 27 pages Latex (w/figures), ApJ, in press. Uses AAS macros,
postscript also available at
http://www.astro.princeton.edu/~library/preprints/pop682.ps.g
Implementation of a non-emergent medical transportation programme at an integrated health system
OBJECTIVES: To implement a unified non-emergency medical transportation (NEMT) service across a large integrated healthcare delivery network.
METHODS: We assessed needs among key organisational stakeholders, then reviewed proposals. We selected a single NEMT vendor best aligned with organisational priorities and implemented this solution system-wide.
RESULTS: Our vendor\u27s hybrid approach combined rideshares with contracted vehicles able to serve patients with equipment and other needs. After 6195 rides in the first year, we observed shorter wait times and lower costs compared with our prior state.
DISCUSSION: Essential lessons included (1) understanding user and patient needs, (2) obtaining complete, accurate and comprehensive baseline data and (3) adapting existing workflows-rather than designing de novo-whenever possible.
CONCLUSIONS: Our implementation of a single-vendor NEMT solution validates the need for NEMT at large healthcare organisations, geographical challenges to establishing NEMT organisation-wide, and the importance of baseline data and stakeholder engagement
Microarray analysis of E9.5 reduced folate carrier (RFC1; Slc19a1) knockout embryos reveals altered expression of genes in the cubilin-megalin multiligand endocytic receptor complex
<p>Abstract</p> <p>Background</p> <p>The reduced folate carrier (<it>RFC1</it>) is an integral membrane protein and facilitative anion exchanger that mediates delivery of 5-methyltetrahydrofolate into mammalian cells. Adequate maternal-fetal transport of folate is necessary for normal embryogenesis. Targeted inactivation of the murine <it>RFC1 </it>gene results in post-implantation embryolethality, but daily folic acid supplementation of pregnant dams prolongs survival of homozygous embryos until mid-gestation. At E10.5 <it>RFC1</it><sup>-/- </sup>embryos are developmentally delayed relative to wildtype littermates, have multiple malformations, including neural tube defects, and die due to failure of chorioallantoic fusion. The mesoderm is sparse and disorganized, and there is a marked absence of erythrocytes in yolk sac blood islands. The identification of alterations in gene expression and signaling pathways involved in the observed dysmorphology following inactivation of RFC1-mediated folate transport are the focus of this investigation.</p> <p>Results</p> <p>Affymetrix microarray analysis of the relative gene expression profiles in whole E9.5 <it>RFC1</it><sup>-/- </sup>vs. <it>RFC1</it><sup>+/+ </sup>embryos identified 200 known genes that were differentially expressed. Major ontology groups included transcription factors (13.04%), and genes involved in transport functions (ion, lipid, carbohydrate) (11.37%). Genes that code for receptors, ligands and interacting proteins in the cubilin-megalin multiligand endocytic receptor complex accounted for 9.36% of the total, followed closely by several genes involved in hematopoiesis (8.03%). The most highly significant gene network identified by Ingenuityâą Pathway analysis included 12 genes in the cubilin-megalin multiligand endocytic receptor complex. Altered expression of these genes was validated by quantitative RT-PCR, and immunohistochemical analysis demonstrated that megalin protein expression disappeared from the visceral yolk sac of <it>RFC1</it><sup>-/- </sup>embryos, while cubilin protein was widely misexpressed.</p> <p>Conclusion</p> <p>Inactivation of <it>RFC1 </it>impacts the expression of several ligands and interacting proteins in the cubilin-amnionless-megalin complex that are involved in the maternal-fetal transport of folate and other nutrients, lipids and morphogens such as sonic hedgehog (Shh) and retinoids that play critical roles in normal embryogenesis.</p
An Improved Photometric Calibration of the Sloan Digital Sky Survey Imaging Data
We present an algorithm to photometrically calibrate wide field optical
imaging surveys, that simultaneously solves for the calibration parameters and
relative stellar fluxes using overlapping observations. The algorithm decouples
the problem of "relative" calibrations, from that of "absolute" calibrations;
the absolute calibration is reduced to determining a few numbers for the entire
survey. We pay special attention to the spatial structure of the calibration
errors, allowing one to isolate particular error modes in downstream analyses.
Applying this to the Sloan Digital Sky Survey imaging data, we achieve ~1%
relative calibration errors across 8500 sq.deg. in griz; the errors are ~2% for
the u band. These errors are dominated by unmodelled atmospheric variations at
Apache Point Observatory. These calibrations, dubbed "ubercalibration", are now
public with SDSS Data Release 6, and will be a part of subsequent SDSS data
releases.Comment: 16 pages, 17 figures, matches version accepted in ApJ. These
calibrations are available at http://www.sdss.org/dr
The Angular Correlation Function of Galaxies from Early SDSS Data
The Sloan Digital Sky Survey is one of the first multicolor photometric and
spectroscopic surveys designed to measure the statistical properties of
galaxies within the local Universe. In this Letter we present some of the
initial results on the angular 2-point correlation function measured from the
early SDSS galaxy data. The form of the correlation function, over the
magnitude interval 18<r*<22, is shown to be consistent with results from
existing wide-field, photographic-based surveys and narrower CCD galaxy
surveys. On scales between 1 arcminute and 1 degree the correlation function is
well described by a power-law with an exponent of ~ -0.7. The amplitude of the
correlation function, within this angular interval, decreases with fainter
magnitudes in good agreement with analyses from existing galaxy surveys. There
is a characteristic break in the correlation function on scales of
approximately 1-2 degrees. On small scales, < 1', the SDSS correlation function
does not appear to be consistent with the power-law form fitted to the 1'<
theta <0.5 deg data. With a data set that is less than 2% of the full SDSS
survey area, we have obtained high precision measurements of the power-law
angular correlation function on angular scales 1' < theta < 1 deg, which are
robust to systematic uncertainties. Because of the limited area and the highly
correlated nature of the error covariance matrix, these initial results do not
yet provide a definitive characterization of departures from the power-law form
at smaller and larger angles. In the near future, however, the area of the SDSS
imaging survey will be sufficient to allow detailed analysis of the small and
large scale regimes, measurements of higher-order correlations, and studies of
angular clustering as a function of redshift and galaxy type
Cross-Correlation of the Cosmic Microwave Background with the 2MASS Galaxy Survey: Signatures of Dark Energy, Hot Gas, and Point Sources
We cross-correlate the Cosmic Microwave Background (CMB) temperature
anisotropies observed by the Wilkinson Microwave Anisotropy Probe (WMAP) with
the projected distribution of extended sources in the Two Micron All Sky Survey
(2MASS). By modelling the theoretical expectation for this signal, we extract
the signatures of dark energy (Integrated Sachs-Wolfe effect;ISW), hot gas
(thermal Sunyaev-Zeldovich effect;thermal SZ), and microwave point sources in
the cross-correlation. Our strongest signal is the thermal SZ, at the 3.1-3.7
\sigma level, which is consistent with the theoretical prediction based on
observations of X-ray clusters. We also see the ISW signal at the 2.5 \sigma
level, which is consistent with the expected value for the concordance LCDM
cosmology, and is an independent signature of the presence of dark energy in
the universe. Finally, we see the signature of microwave point sources at the
2.7 \sigma level.Comment: 35 pages (preprint format), 8 figures. In addition to minor revisions
based on referee's comments, after correcting for a bug in the code, the SZ
detection is consistent with the X-ray observations. Accepeted for
publication in Physical Review
Another intermediate mass black hole in a starburst galaxy?: The luminous X-ray source in NGC 3628 reappears
In a 52 ks-long Chandra ACIS-S observation of the nearby starburst galaxy NGC
3628, obtained to study the starburst-driven outflow from this galaxy, we have
detected a very luminous (L_X = 1.1e40 erg/s in the 0.3-8.0 keV energy band)
point source located at least 20 arcsec (~970 pc) from the nucleus of the
galaxy. No radio, optical or near-IR counterpart to this source has been found.
This is most probably the reappearance of the strongly-variable
X-ray-luminous source discovered by Dahlem et al (1995), which faded by a
factor >27 between December 1991 and March 1994 (at which point it had faded
below the detection limit in a ROSAT HRI observation). This source is clearly a
member of an enigmatic class of X-ray sources that are considerably more
luminous than conventional X-ray binaries but less luminous than AGN, and which
are not found at the dynamical center of the host galaxy.
The Chandra spectrum is best-fit by an absorbed power law model with a photon
index of Gamma = 1.8+/-0.2, similar to that seen in Galactic BH binary
candidates in their hard state. Bremsstrahlung models or multi-color disk
models (the favored spectral model for objects in this class based on ASCA
observations) can provide statistically acceptable fits only if the data at
energies E > 5 keV is ignored. This is one of the first X-ray spectra of such
an object that is unambiguously that of the source alone, free from the
spectral contamination by X-ray emission from the rest of the galaxy that
affects previous spectral studies of these objects using ASCA.Comment: Accepted for publication in the Ap
MIGHTEE-HI: The first MeerKAT HI mass function from an untargeted interferometric survey
We present the first measurement of the HI mass function (HIMF) using data
from MeerKAT, based on 276 direct detections from the MIGHTEE Survey Early
Science data covering a period of approximately a billion years (). This is the first HIMF measured using interferometric data over
non-group or cluster field, i.e. a deep blank field. We constrain the
parameters of the Schechter function which describes the HIMF with two
different methods: and Modified Maximum Likelihood (MML).
We find a low-mass slope , `knee' mass
and normalisation
(
kms Mpc) for and
, `knee' mass and normalisation for MML. When using we
find both the low-mass slope and `knee' mass to be consistent within
with previous studies based on single-dish surveys. The cosmological mass
density of HI is found to be slightly larger than previously reported:
from and from MML but consistent within the uncertainties. We find
no evidence for evolution of the HIMF over the last billion years.Comment: 13 pages, 9 figures, accepted for publication in MNRA
Romosozumab (sclerostin monoclonal antibody) versus teriparatide in postmenopausal women with osteoporosis transitioning from oral bisphosphonate therapy : a randomised, open-label, phase 3 trial
Background: Previous bisphosphonate treatment attenuates the bone-forming effect of teriparatide. We compared the effects of 12 months of romosozumab (AMG 785), a sclerostin monoclonal antibody, versus teriparatide on bone mineral density (BMD) in women with postmenopausal osteoporosis transitioning from bisphosphonate therapy.
Methods: This randomised, phase 3, open-label, active-controlled study was done at 46 sites in North America, Latin America, and Europe. We enrolled women (aged >= 55 to <= 90 years) with postmenopausal osteoporosis who had taken an oral bisphosphonate for at least 3 years before screening and alendronate the year before screening; an areal BMD T score of -2.5 or lower at the total hip, femoral neck, or lumbar spine; and a history of fracture. Patients were randomly assigned (1:1) via an interactive voice response system to receive subcutaneous romosozumab (210 mg once monthly) or subcutaneous teriparatide (20 mu g once daily). The primary endpoint was percentage change from baseline in areal BMD by dual-energy x-ray absorptiometry at the total hip through month 12 (mean of months 6 and 12), which used a linear mixed effects model for repeated measures and represented the mean treatment effect at months 6 and 12. All randomised patients with a baseline measurement and at least one post-baseline measurement were included in the efficacy analysis. This trial is registered with ClinicalTrials.gov, number NCT01796301.
Findings: Between Jan 31, 2013, and April 29, 2014, 436 patients were randomly assigned to romosozumab (n=218) or teriparatide (n=218). 206 patients in the romosozumab group and 209 in the teriparatide group were included in the primary efficacy analysis. Through 12 months, the mean percentage change from baseline in total hip areal BMD was 2.6% (95% CI 2.2 to 3.0) in the romosozumab group and -0.6% (-1.0 to -0.2) in the teriparatide group; difference 3.2% (95% CI 2.7 to 3.8; p<0.0001). The frequency of adverse events was generally balanced between treatment groups. The most frequently reported adverse events were nasopharyngitis (28 [13%] of 218 in the romosozumab group vs 22 [10%] of 214 in the teriparatide group), hypercalcaemia (two [<1%] vs 22 [10%]), and arthralgia (22 [10%] vs 13 [6%]). Serious adverse events were reported in 17 (8%) patients on romosozumab and in 23 (11%) on teriparatide; none were judged treatment related. There were six (3%) patients in the romosozumab group compared with 12 (6%) in the teriparatide group with adverse events leading to investigational product withdrawal.
Interpretation: Transition to a bone-forming agent is common practice in patients treated with bisphosphonates, such as those who fracture while on therapy. In such patients, romosozumab led to gains in hip BMD that were not observed with teriparatide. These data could inform clinical decisions for patients at high risk of fracture
A newly recognized very young supernova remnant in M83
As part of a spectroscopic survey of supernova remnant candidates in M83 using the Gemini-South telescope and Gemini Multi-Object Spectrograph, we have discovered one object whose spectrum shows very broad lines at Hα, [O I] λλ6300, 6363, and [O III] λλ4959, 5007, similar to those from other objects classified as "late time supernovae". Although six historical supernovae have been observed in M83 since 1923, none were seen at the location of this object. Hubble Space Telescope (HST) Wide Field Camera 3 images show a nearly unresolved emission source, while Chandra and ATCA data reveal a bright X-ray source and nonthermal radio source at the position. Objects in other galaxies showing similar spectra are only decades post-supernova, which raises the possibility that the supernova that created this object occurred during the last century but was missed. Using photometry of nearby stars from the HST data, we suggest the precursor was at least 17 M â, and the presence of broad Hα in the spectrum makes a type II supernova likely. The supernova must predate the 1983 Very Large Array radio detection of the object. We suggest examination of archival images of M83 to search for evidence of the supernova event that gave rise to this object, and thus provide a precise age
- âŠ