250 research outputs found
Arithmetic computation with probability words and numbers
Probability information is regularly communicated to experts who must fuse multiple estimates to support decision-making. Such information is often communicated verbally (e.g., “likely”) rather than with precise numeric (point) values (e.g., “.75”), yet people are not taught to perform arithmetic on verbal probabilities. We hypothesized that the accuracy and logical coherence of averaging and multiplying probabilities will be poorer when individuals receive probability information in verbal rather than numerical point format. In four experiments (N = 213, 201, 26, and 343, respectively), we manipulated probability communication format between-subjects. Participants averaged and multiplied sets of four probabilities. Across experiments, arithmetic accuracy and coherence was significantly better with point than with verbal probabilities. These findings generalized between expert (intelligence analysts) and non-expert samples and when controlling for calculator use. Experiment 4 revealed an important qualification: whereas accuracy and coherence were better among participants presented with point probabilities than with verbal probabilities, imprecise numeric probability ranges (e.g., “.70 to .80”) afforded no computational advantage over verbal probabilities. Experiment 4 also revealed that the advantage of the point over the verbal format is partially mediated by strategy use. Participants presented with point estimates are more likely to use mental computation than guesswork, and mental computation was found to be associated with better accuracy. Our findings suggest that where computation is important, probability information should be communicated to end users with precise numeric probabilities
Effectiveness and safety of erythropoiesis-stimulating agent use in the perioperative period
postprin
Detection of Outflowing and Extraplanar Gas in Disks in an Assembling Galaxy Cluster at z=0.37
We detect ionized gas characteristics indicative of winds in three
disk-dominated galaxies that are members of a super-group at z=0.37 that will
merge to form a Coma-mass cluster. All three galaxies are IR-luminous (L_IR > 4
x 10^{10} L_sun, SFR >8 M_sun per year) and lie outside the X-ray cores of the
galaxy groups. We find that the most IR-luminous galaxy has strong blue and
redshifted emission lines with velocities of ~ +/-200 km/s and a third,
blueshifted (~ 900 km/s) component. This galaxy's line-widths (Hb, [OIII]5007,
[NII], Ha) correspond to velocities of 100-1000 km/s. We detect extraplanar gas
in two of three galaxies with SFR > 8 M_sun per year whose orientations are
approximately edge-on and which have IFU spaxels off the stellar disk. IFU maps
reveal that the extraplanar gas extends to r_h ~ 10 kpc; [NII] and Ha
line-widths correspond to velocities of ~200-400 km/s in the disk and decrease
to ~50-150 km/s above the disk. Multi-wavelength observations indicate that the
emission is dominated by star formation. Including the most IR-luminous galaxy
we find that 18% of supergroup members with SFR > 8 M_sun per year show ionized
gas characteristics indicative of outflows. This is a lower limit as showing
that gas is outflowing in the remaining, moderately inclined, galaxies requires
a non-trivial decoupling of contributions to the emission lines from rotational
and turbulent motion. Ionized gas mass loss in these winds is ~0.1 M_sun per
year for each galaxy, although the winds are likely to entrain significantly
larger amounts of mass in neutral and molecular gas.Comment: 6 pages, 3 figures (slightly degraded in quality), accepted for
publication in ApJ
XMM-Newton and Chandra observations of three X-ray faint early-type galaxies
We present XMM-Newton observations of three X-ray under-luminous elliptical
galaxies, NGC 3585, NGC 4494 and NGC 5322. All three galaxies have relatively
large optical luminosities (log LB=10.35-10.67 solar) but have X-ray
luminosities consistent with emission from discrete sources only. In
conjunction with a Chandra observation of NGC 3585, we analyse the XMM data and
show that the three galaxies are dominated by discrete source emission, but do
possess some X-ray emitting gas. The gas is at relatively low temperatures,
kT=0.25-0.44 keV. All three galaxies show evidence of recent dynamical
disturbance and formation through mergers, including kinematically distinct
cores, young stellar ages, and embedded stellar disks. This leads us to
conclude that the galaxies formed relatively recently and have yet to build up
large X-ray halos. They are likely to be in a developmental phase where the
X-ray gas has a very low density, making it undetectable outside the galaxy
core. However, if the gas is a product of stellar mass loss, as seems most
probable, we would expect to observe supersolar metal abundances. While
abundance is not well constrained by the data, we find best fit abundances <0.1
solar for single-temperature models, and it seems unlikely that we could
underestimate the metallicity by such a large factor.Comment: Accepted for publication in MNRAS, 12 pages, 8 postscript figure
Discs in early-type lensing galaxies: effects on magnification ratios and measurements of
Observations of early-type galaxies, both in the local universe and in
clusters at medium redshifts, suggest that these galaxies often contain discs
or disc-like structures. Using the results of Kelson et al. (2000) for the
incidence of disc-components among the galaxies in the redshift z=0.33 cluster
CL 1358+62, we investigate the effect of disc structures on the lensing
properties of early-type galaxies. Statistical properties, like magnification
cross sections and the expected number of quad (four-image) lens systems, are
not affected greatly by the inclusion of discs that contain less than about 10
per cent of the total stellar mass. However, the properties of individual lens
systems are affected. We estimate that 10-30 per cent of all quad lens systems,
with early-type deflector galaxies, would be affected measurably by the
presence of disc components. Intriguingly, the image magnification ratios are
altered significantly. The amplitude of the predicted change is sufficient to
explain the observed magnification ratios in systems like B1422+231 without
requiring compact substructure. Furthermore, time delays between images also
change; fitting a bulge-only model to early-type lenses that in fact contain a
disc would yield a value of the Hubble constant H_0 that is systematically too
low by about 25 per cent.Comment: Accepted for publication in MNRAS. 17 pages, 14 figures, 3 tables.
Mainly minor changes to submitted version. Includes a more extended
discussion on evidence of discs from light profile
CMB Telescopes and Optical Systems
The cosmic microwave background radiation (CMB) is now firmly established as
a fundamental and essential probe of the geometry, constituents, and birth of
the Universe. The CMB is a potent observable because it can be measured with
precision and accuracy. Just as importantly, theoretical models of the Universe
can predict the characteristics of the CMB to high accuracy, and those
predictions can be directly compared to observations. There are multiple
aspects associated with making a precise measurement. In this review, we focus
on optical components for the instrumentation used to measure the CMB
polarization and temperature anisotropy. We begin with an overview of general
considerations for CMB observations and discuss common concepts used in the
community. We next consider a variety of alternatives available for a designer
of a CMB telescope. Our discussion is guided by the ground and balloon-based
instruments that have been implemented over the years. In the same vein, we
compare the arc-minute resolution Atacama Cosmology Telescope (ACT) and the
South Pole Telescope (SPT). CMB interferometers are presented briefly. We
conclude with a comparison of the four CMB satellites, Relikt, COBE, WMAP, and
Planck, to demonstrate a remarkable evolution in design, sensitivity,
resolution, and complexity over the past thirty years.Comment: To appear in: Planets, Stars and Stellar Systems (PSSS), Volume 1:
Telescopes and Instrumentatio
Dark sectors 2016 Workshop: community report
This report, based on the Dark Sectors workshop at SLAC in April 2016,
summarizes the scientific importance of searches for dark sector dark matter
and forces at masses beneath the weak-scale, the status of this broad
international field, the important milestones motivating future exploration,
and promising experimental opportunities to reach these milestones over the
next 5-10 years
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