111 research outputs found
Paper Session III-B - The Prospector\u27s Proposal: Research Advancing Survivability Through Resource Options
As a group of nine Astronautical Engineering majors, we have identified a problem of great concern. It involves the scarcity of strategic materials and the possibility that our supply will be cut off. The Prospector\u27s Proposal is our solution. This proposal involves a prospecting mission to the asteroid belt, specifically Ceres. Using heavy lift vehicles, we will put our spacecraft into orbit where it will be assembled. A nuclear drive will provide propulsion for the unmanned probe. A landing craft will transport a mobile unit to the surface. This unit will collect samples that may contain sufficient quantities of the necessary materials to justify future mining. We have set a launch date for Spring 2001
Star-gas misalignment in galaxies: I. The properties of galaxies from the Horizon-AGN simulation and comparisons to SAMI
Recent integral field spectroscopy observations have found that about 11% of
galaxies show star-gas misalignment. The misalignment possibly results from
external effects such as gas accretion, interaction with other objects, and
other environmental effects, hence providing clues to these effects. We explore
the properties of misaligned galaxies using Horizon-AGN, a large-volume
cosmological simulation, and compare the result with the result of the
Sydney-AAO Multi-object integral field spectrograph (SAMI) Galaxy Survey.
Horizon-AGN can match the overall misalignment fraction and reproduces the
distribution of misalignment angles found by observations surprisingly closely.
The misalignment fraction is found to be highly correlated with galaxy
morphology both in observations and in the simulation: early-type galaxies are
substantially more frequently misaligned than late-type galaxies. The gas
fraction is another important factor associated with misalignment in the sense
that misalignment increases with decreasing gas fraction. However, there is a
significant discrepancy between the SAMI and Horizon-AGN data in the
misalignment fraction for the galaxies in dense (cluster) environments. We
discuss possible origins of misalignment and disagreement.Comment: 23 pages with 15 figures. Accepted for publication in Ap
The Lantern Vol. 63, No. 2, Spring 1996
• Poet, Lead Me On • St. Patrick\u27s Day • The Last Three Days • The Impressionable • Roundabout • The Bench • Carnivorous • Kyrie • Second Glance • Porch • Cruel Design • A Mime • Flaxen Crown • My Embryonic Ocean of Love • Stone Matrix • Voices from the Past • Skipping the Bullfight: Toreadors and Gaudi • Another Part of My Lacolonialism • Translucent Pane • Linguistics • Treehouse • A Disagreeable Music Piece • Vigil • A Brief History of American Poetry in Englishhttps://digitalcommons.ursinus.edu/lantern/1148/thumbnail.jp
The XMM Cluster Survey: X-ray analysis methodology
The XMM Cluster Survey (XCS) is a serendipitous search for galaxy clusters
using all publicly available data in the XMM-Newton Science Archive. Its main
aims are to measure cosmological parameters and trace the evolution of X-ray
scaling relations. In this paper we describe the data processing methodology
applied to the 5,776 XMM observations used to construct the current XCS source
catalogue. A total of 3,675 > 4-sigma cluster candidates with > 50
background-subtracted X-ray counts are extracted from a total non-overlapping
area suitable for cluster searching of 410 deg^2. Of these, 993 candidates are
detected with > 300 background-subtracted X-ray photon counts, and we
demonstrate that robust temperature measurements can be obtained down to this
count limit. We describe in detail the automated pipelines used to perform the
spectral and surface brightness fitting for these candidates, as well as to
estimate redshifts from the X-ray data alone. A total of 587 (122) X-ray
temperatures to a typical accuracy of < 40 (< 10) per cent have been measured
to date. We also present the methodology adopted for determining the selection
function of the survey, and show that the extended source detection algorithm
is robust to a range of cluster morphologies by inserting mock clusters derived
from hydrodynamical simulations into real XMM images. These tests show that the
simple isothermal beta-profiles is sufficient to capture the essential details
of the cluster population detected in the archival XMM observations. The
redshift follow-up of the XCS cluster sample is presented in a companion paper,
together with a first data release of 503 optically-confirmed clusters.Comment: MNRAS accepted, 45 pages, 38 figures. Our companion paper describing
our optical analysis methodology and presenting a first set of confirmed
clusters has now been submitted to MNRA
The SAMI Galaxy Survey: a statistical approach to an optimal classification of stellar kinematics in galaxy surveys
Large galaxy samples from multi-object IFS surveys now allow for a
statistical analysis of the z~0 galaxy population using resolved kinematics.
However, the improvement in number statistics comes at a cost, with
multi-object IFS survey more severely impacted by the effect of seeing and
lower S/N. We present an analysis of ~1800 galaxies from the SAMI Galaxy Survey
and investigate the spread and overlap in the kinematic distributions of the
spin parameter proxy as a function of stellar mass and
ellipticity. For SAMI data, the distributions of galaxies identified as regular
and non-regular rotators with \textsc{kinemetry} show considerable overlap in
the - diagram. In contrast, visually classified
galaxies (obvious and non-obvious rotators) are better separated in
space, with less overlap of both distributions. Then, we use a
Bayesian mixture model to analyse the observed
- distribution. Below
, a single beta distribution is sufficient
to fit the complete distribution, whereas a second beta
distribution is required above to account
for a population of low- galaxies. While the Bayesian mixture
model presents the cleanest separation of the two kinematic populations, we
find the unique information provided by visual classification of kinematic maps
should not be disregarded in future studies. Applied to mock-observations from
different cosmological simulations, the mixture model also predicts bimodal
distributions, albeit with different positions of the
peaks. Our analysis validates the conclusions from previous
smaller IFS surveys, but also demonstrates the importance of using kinematic
selection criteria that are dictated by the quality of the observed or
simulated data.Comment: 30 pages and 17 figures, accepted for publication in MNRAS. Abstract
abridged for Arxiv. The key figures of the paper are: 3, 7, 8, and 1
Support for UNRWA's survival
The United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA) provides life-saving humanitarian aid for 5·4 million Palestine refugees now entering their eighth decade of statelessness and conflict. About a third of Palestine refugees still live in 58 recognised camps. UNRWA operates 702 schools and 144 health centres, some of which are affected by the ongoing humanitarian disasters in Syria and the Gaza Strip. It has dramatically reduced the prevalence of infectious diseases, mortality, and illiteracy. Its social services include rebuilding infrastructure and homes that have been destroyed by conflict and providing cash assistance and micro-finance loans for Palestinians whose rights are curtailed and who are denied the right of return to their homeland
LSST Science Book, Version 2.0
A survey that can cover the sky in optical bands over wide fields to faint
magnitudes with a fast cadence will enable many of the exciting science
opportunities of the next decade. The Large Synoptic Survey Telescope (LSST)
will have an effective aperture of 6.7 meters and an imaging camera with field
of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over
20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with
fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a
total point-source depth of r~27.5. The LSST Science Book describes the basic
parameters of the LSST hardware, software, and observing plans. The book
discusses educational and outreach opportunities, then goes on to describe a
broad range of science that LSST will revolutionize: mapping the inner and
outer Solar System, stellar populations in the Milky Way and nearby galaxies,
the structure of the Milky Way disk and halo and other objects in the Local
Volume, transient and variable objects both at low and high redshift, and the
properties of normal and active galaxies at low and high redshift. It then
turns to far-field cosmological topics, exploring properties of supernovae to
z~1, strong and weak lensing, the large-scale distribution of galaxies and
baryon oscillations, and how these different probes may be combined to
constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at
http://www.lsst.org/lsst/sciboo
Endovascular strategy or open repair for ruptured abdominal aortic aneurysm: one-year outcomes from the IMPROVE randomized trial.
AIMS: To report the longer term outcomes following either a strategy of endovascular repair first or open repair of ruptured abdominal aortic aneurysm, which are necessary for both patient and clinical decision-making. METHODS AND RESULTS: This pragmatic multicentre (29 UK and 1 Canada) trial randomized 613 patients with a clinical diagnosis of ruptured aneurysm; 316 to an endovascular first strategy (if aortic morphology is suitable, open repair if not) and 297 to open repair. The principal 1-year outcome was mortality; secondary outcomes were re-interventions, hospital discharge, health-related quality-of-life (QoL) (EQ-5D), costs, Quality-Adjusted-Life-Years (QALYs), and cost-effectiveness [incremental net benefit (INB)]. At 1 year, all-cause mortality was 41.1% for the endovascular strategy group and 45.1% for the open repair group, odds ratio 0.85 [95% confidence interval (CI) 0.62, 1.17], P = 0.325, with similar re-intervention rates in each group. The endovascular strategy group and open repair groups had average total hospital stays of 17 and 26 days, respectively, P < 0.001. Patients surviving rupture had higher average EQ-5D utility scores in the endovascular strategy vs. open repair groups, mean differences 0.087 (95% CI 0.017, 0.158), 0.068 (95% CI -0.004, 0.140) at 3 and 12 months, respectively. There were indications that QALYs were higher and costs lower for the endovascular first strategy, combining to give an INB of £3877 (95% CI £253, £7408) or €4356 (95% CI €284, €8323). CONCLUSION: An endovascular first strategy for management of ruptured aneurysms does not offer a survival benefit over 1 year but offers patients faster discharge with better QoL and is cost-effective. CLINICAL TRIAL REGISTRATION: ISRCTN 48334791
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