549 research outputs found
The Luminosity Function at z~8 from 97 Y-band dropouts: Inferences About Reionization
[Abbreviated] We present the largest search to date for Lyman break
galaxies (LBGs) based on 350 arcmin of HST observations in the V-, Y-, J-
and H-bands from the Brightest of Reionizing Galaxies (BoRG) survey. The BoRG
dataset includes 50 arcmin of new data and deeper observations of two
previous BoRG pointings, from which we present 9 new LBG candidates,
bringing the total number of BoRG LBGs to 38 with (AB system). We introduce a new Bayesian formalism for
estimating the galaxy luminosity function (LF), which does not require binning
(and thus smearing) of the data and includes a likelihood based on the formally
correct binomial distribution as opposed to the often used approximate Poisson
distribution. We demonstrate the utility of the new method on a sample of
LBGs that combines the bright BoRG galaxies with the fainter sources published
in Bouwens et al. (2012) from the HUDF and ERS programs. We show that the
LF is well described by a Schechter function with a characteristic
magnitude , a faint-end slope of , and a number density of . Integrated down to this
LF yields a luminosity density, . Our LF analysis
is consistent with previously published determinations within 1. We
discuss the implication of our study for the physics of reionization. By
assuming theoretically motivated priors on the clumping factor and the photon
escape fraction we show that the UV LF from galaxy samples down to
can ionize only 10-50% of the neutral hydrogen at . Full reionization
would require extending the LF down to .Comment: Accepted for publication in ApJ, 22 pages, 15 figure
Preference Elicitation Tool for Abnormal Uterine Bleeding Treatment: A Randomized Controlled Trial
Background
It is estimated that one-third of women will experience abnormal menstrual bleeding. The majority of these cases are not due to cancer or pregnancy complications and, as a result, women are faced with a variety of treatment alternatives, the selection of which is largely dependent on personal preferences for care rather than clinical outcomes.
Objective
This randomized trial was designed to evaluate a preference elicitation tool to promote physician–patient collaborative decision making for treatment of abnormal uterine bleeding (AUB).
Methods
Adaptive conjoint analysis (ACA) was used to create a preference elicitation tool in English and in Spanish. Women with AUB were enrolled to the study and randomly assigned to ACA or usual counseling at the initial clinic visit at four clinics (three in Indianapolis, IN, USA, and one in Southern Pines, NC, USA). The ACA tool elicited preferences across eight attributes: treatment efficacy; sexual function; medical care; cost; fertility; frequency of medication use; permanence; and recovery time. t tests were used to compare differences in the primary outcomes of decision regret and treatment satisfaction at the follow-up visit. The study was designed to have 80 % power to detect significant differences between groups for the primary outcomes of regret and satisfaction.
Results
Women were enrolled in the study between September 2009 and March 2012. 183 participants were randomized to ACA and 191 to usual counseling. Overall, mean (standard deviation) treatment satisfaction was high at 35.71 (9.72) (scale of 0–44), and decision regret was low at 25.9 (21.0) (scale of 0–100), creating ceiling effects for the selected outcome variables; there were no significant differences between the ACA and control groups at the follow-up assessment. There was a strong inverse relationship between age and decision regret (p = 0.007). Exploratory subgroup analysis in the youngest quartile comprising 64 women aged 19–35 years showed a statistically non-significant difference in mean regret scores for the ACA group versus usual counseling (24.6 vs. 34.6, respectively; p = 0.08).
Conclusions
A preference elicitation tool at the initial consultation visit did not reduce decision regret or improve treatment satisfaction among patients with AUB; however, there is a need for additional research to further understand this tool’s potential role in promoting collaborative decision making, which may be particularly important among younger women
HST Grism Observations of a Gravitationally Lensed Redshift 10 Galaxy
We present deep spectroscopic observations of a Lyman-break galaxy candidate
(hereafter MACS1149-JD) at with the Space
Telescope () WFC3/IR grisms. The grism observations were taken at
4 distinct position angles, totaling 34 orbits with the G141 grism, although
only 19 of the orbits are relatively uncontaminated along the trace of
MACS1149-JD. We fit a 3-parameter (, F160W mag, and Ly equivalent
width) Lyman-break galaxy template to the three least contaminated grism
position angles using an MCMC approach. The grism data alone are best fit with
a redshift of ( confidence), in
good agreement with our photometric estimate of
( confidence). Our analysis
rules out Lyman-alpha emission from MACS1149-JD above a equivalent
width of 21 \AA{}, consistent with a highly neutral IGM. We explore a scenario
where the red /IRAC color of the galaxy
previously pointed out in the literature is due to strong rest-frame optical
emission lines from a very young stellar population rather than a 4000 \AA{}
break. We find that while this can provide an explanation for the observed IRAC
color, it requires a lower redshift (), which is less preferred
by the imaging data. The grism data are consistent with both
scenarios, indicating that the red IRAC color can still be explained by a 4000
\AA{} break, characteristic of a relatively evolved stellar population. In this
interpretation, the photometry indicate that a Myr stellar
population is already present in this galaxy only after
the Big Bang.Comment: Accepted to ApJ. This is the accepted versio
The Grism Lens-Amplified Survey from Space (GLASS) X. Sub-kpc resolution gas-phase metallicity maps at cosmic noon behind the Hubble Frontier Fields cluster MACS1149.6+2223
(Abridged) We combine deep HST grism spectroscopy with a new Bayesian method
to derive maps of gas-phase metallicity, nebular dust extinction, and
star-formation rate for 10 star-forming galaxies at high redshift
(). Exploiting lensing magnification by the foreground cluster
MACS1149.6+2223, we reach sub-kpc spatial resolution and push the stellar mass
limit associated with such high-z spatially resolved measurements below
for the first time. Our maps exhibit diverse morphologies,
indicative of various effects such as efficient radial mixing from tidal
torques, rapid accretion of low-metallicity gas, etc., which can affect the gas
and metallicity distributions in individual galaxies. Based upon an exhaustive
sample of all existing sub-kpc metallicity gradients at high-z, we find that
predictions given by analytical chemical evolution models assuming a relatively
extended star-formation profile in the early disk formation phase can explain
the majority of observed gradients, without involving galactic feedback or
radial outflows. We observe a tentative correlation between stellar mass and
metallicity gradient, consistent with the downsizing galaxy formation picture
that more massive galaxies are more evolved into a later phase of disk growth,
where they experience more coherent mass assembly at all radii and thus show
shallower metallicity gradients. In addition, we compile a sample of
homogeneously cross-calibrated integrated metallicity measurements spanning
three orders of magnitude in stellar mass at . We use this sample to
study the mass-metallicity relation (MZR) and test the fundamental metallicity
relation (FMR). The slope of the observed MZR can rule out the momentum-driven
wind model at 3- confidence level. We find no significant offset with
respect to the FMR, taking into account the intrinsic scatter and measurement
uncertainties.Comment: 26 pages, 14 figures, and 6 table
Counteracting Angiotensinogen Small-Interfering RNA-Mediated Antihypertensive Effects with REVERSIR
BACKGROUND: Small-interfering RNA (siRNA) targeting hepatic AGT (angiotensinogen) mRNA depletes AGT, lowering blood pressure for up to 6 months. However, certain situations may require a rapid angiotensin increase. The REVERSIR (RVR) - reverse siRNA silencing technology a potential approach to counteract siRNA effects. METHODS: Spontaneously hypertensive rats received 10 mg/kg AGT siRNA, and 3 weeks later were given AGT-RVR (1, 10, or 20 mg/kg). One week after AGT-RVR dosing, a redose of AGT siRNA assessed its post-AGT-RVR effectiveness for 2 weeks. Additionally, the impact of AGT-RVR after an equihypotensive dose of valsartan (4 mg/kg per day) was examined. RESULTS: Baseline mean arterial pressure (MAP) was 144±1 mm Hg. AGT siRNA reduced MAP by ≈16 mm Hg and AGT by >95%, while renin increased 25-fold. All AGT-RVR doses restored MAP to baseline within 4 to 7 days. Notably, 10 and 20 mg/kg restored AGT and renin to baseline, while 1 mg/kg allowed ≈50% AGT restoration, with renin remaining above baseline. A second AGT siRNA treatment, following 1 mg/kg AGT-RVR, reduced MAP to the same degree as the initial dose, while following 10 mg/kg AGT-RVR, it resulted in ≈50% of the first dose's MAP effect at 2 weeks. The valsartan-induced MAP reduction was unaffected by AGT-RVR. CONCLUSIONS: In spontaneously hypertensive rats, angiotensinogen-RVR dose-dependently reversed AGT siRNA-induced AGT reduction, normalizing MAP. MAP normalization persisted even with 50% recovered AGT levels, likely due to upregulated renin maintaining adequate angiotensin generation. Post-AGT-RVR dosing, a second AGT siRNA dose lowered MAP again.</p
Turbulence Transport Modeling and First Orbit Parker Solar Probe (PSP) Observations
Parker Solar Probe (PSP) achieved its first orbit perihelion on November 6,
2018, reaching a heliocentric distance of about 0.165 au (35.55 R).
Here, we study the evolution of fully developed turbulence associated with the
slow solar wind along the PSP trajectory between 35.55 R and 131.64
R in the outbound direction, comparing observations to a theoretical
turbulence transport model. Several turbulent quantities, such as the
fluctuating kinetic energy and the corresponding correlation length, the
variance of density fluctuations, and the solar wind proton temperature are
determined from the PSP SWEAP plasma data along its trajectory between 35.55
R and 131.64 R. The evolution of the PSP derived turbulent
quantities are compared to the numerical solutions of the nearly incompressible
magnetohydrodynamic (NI MHD) turbulence transport model recently developed by
Zank et al. (2017). We find reasonable agreement between the theoretical and
observed results. On the basis of these comparisons, we derive other
theoretical turbulent quantities, such as the energy in forward and backward
propagating modes, the total turbulent energy, the normalized residual energy
and cross-helicity, the fluctuating magnetic energy, and the correlation
lengths corresponding to forward and backward propagating modes, the residual
energy, and the fluctuating magnetic energy
Testing the Solar Probe Cup, an Instrument Designed to Touch the Sun
Solar Probe Plus will be the first, fastest, and closest mission to the sun, providing the first direct sampling of the sub-Alfvenic corona. The Solar Probe Cup (SPC) is a unique re-imagining of the traditional Faraday Cup design and materials for immersion in this high temperature environment. Sending an instrument of this type into a never-seen particle environment requires extensive characterization prior to launch to establish sufficient measurement accuracy and instrument response. To reach this end, a slew of tests for allowing SPC to see ranges of appropriate ions and electrons, as well as a facility that reproduces solar photon spectra and fluxes for this mission. Having already tested the SPC at flight like temperatures with no significant modification of the noise floor, we recently completed a round of particle testing to see if the deviations in Faraday Cup design fundamentally change the operation of the instrument. Results and implications from these tests will be presented, as well as performance comparisons to cousin instruments such as those on the WIND spacecraft
Schoolwide Application of Positive Behavior Support in an Urban High School:. Journal Of Positive Behavior Interventions
Abstract: The nuances of the application of schoolwide positive behavior supports (PBS) in an urban high school setting were investigated. Impact of implementation was measured using qualitative interviews and observations, including the School-wide Evaluation Tool (SET), Effective Behavior Support Survey, Student Climate Survey, and office disciplinary referrals. The results indicated that schoolwide PBS was implemented in an urban high school setting with some success. The overall level of implementation of PBS reached 80% as measured by the SET. Staff and teachers increased their level of perceived priority for implementing PBS in their school. A decrease in monthly discipline referrals to the office and the proportion of students who required secondary and tertiary supports was noted. These findings seem to indicate that PBS may be an important process for improving outcomes for teachers and students in urban high school settings
The Color Variability of Quasars
We quantify quasar color-variability using an unprecedented variability
database - ugriz photometry of 9093 quasars from SDSS Stripe 82, observed over
8 years at ~60 epochs each. We confirm previous reports that quasars become
bluer when brightening. We find a redshift dependence of this blueing in a
given set of bands (e.g. g and r), but show that it is the result of the flux
contribution from less-variable or delayed emission lines in the different SDSS
bands at different redshifts. After correcting for this effect, quasar
color-variability is remarkably uniform, and independent not only of redshift,
but also of quasar luminosity and black hole mass. The color variations of
individual quasars, as they vary in brightness on year timescales, are much
more pronounced than the ranges in color seen in samples of quasars across many
orders of magnitude in luminosity. This indicates distinct physical mechanisms
behind quasar variability and the observed range of quasar luminosities at a
given black hole mass - quasar variations cannot be explained by changes in the
mean accretion rate. We do find some dependence of the color variability on the
characteristics of the flux variations themselves, with fast, low-amplitude,
brightness variations producing more color variability. The observed behavior
could arise if quasar variability results from flares or ephemeral hot spots in
an accretion disc.Comment: Accepted for publication in ApJ - in press, 17 pages, 14 figures -
v2: abstract typo corrected & reference clean-u
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