338 research outputs found
Discrete event simulation model for planning Level 2 “step-down” bed needs using NEMS
In highly congested hospitals it may be common for patients to overstay at Intensive Care Units (ICU) due to blockages and imbalances in capacity. This is inadequate clinically, as patients occupy a service they no longer need; operationally, as it disrupts flow from upstream units; and financially as ICU beds are more expensive than ward beds. Step-down beds, also known as Level 2 beds, have become an increasingly popular and less expensive alternative to ICU beds to deal with this issue. We developed a discrete event simulation model that estimates Level 2 bed needs for a large university hospital. The model innovates by simulating the entirety of the hospital’s inpatient flow and most importantly, the ICU’s daily stochastic flows based on a nursing workload scoring metrics called “Nine Equivalents of Nursing Manpower Use Score” (NEMS). Using data from a large academic hospital, the model shows the benefits of Level 2 beds in improving both patient flow and costs
IDCS J1426.5+3508: The Most Massive Galaxy Cluster at
We present a deep (100 ks) Chandra observation of IDCS J1426.5+3508, a
spectroscopically confirmed, infrared-selected galaxy cluster at .
This cluster is the most massive galaxy cluster currently known at ,
based on existing Sunyaev-Zel'dovich (SZ) and gravitational lensing detections.
We confirm this high mass via a variety of X-ray scaling relations, including
-M, -M, -M and -M, finding a tight distribution of masses
from these different methods, spanning M = 2.3-3.3
M, with the low-scatter -based mass M. IDCS J1426.5+3508 is currently the
only cluster at for which X-ray, SZ and gravitational lensing mass
estimates exist, and these are in remarkably good agreement. We find a
relatively tight distribution of the gas-to-total mass ratio, employing total
masses from all of the aforementioned indicators, with values ranging from
= 0.087-0.12. We do not detect metals in the intracluster medium
(ICM) of this system, placing a 2 upper limit of . This upper limit on the metallicity suggests that this system may
still be in the process of enriching its ICM. The cluster has a dense,
low-entropy core, offset by 30 kpc from the X-ray centroid, which makes
it one of the few "cool core" clusters discovered at , and the first
known cool core cluster at . The offset of this core from the
large-scale centroid suggests that this cluster has had a relatively recent
(500 Myr) merger/interaction with another massive system.Comment: Minor changes to match accepted version, results unchanged; ApJ in
pres
Star Formation and AGN Activity in Galaxy Clusters from : a Multi-wavelength Analysis Featuring /PACS
We present a detailed, multi-wavelength study of star formation (SF) and AGN
activity in 11 near-infrared (IR) selected, spectroscopically confirmed,
massive () galaxy clusters at . Using
new, deep /PACS imaging, we characterize the optical to far-IR
spectral energy distributions (SEDs) for IR-luminous cluster galaxies, finding
that they can, on average, be well described by field galaxy templates.
Identification and decomposition of AGN through SED fittings allows us to
include the contribution to cluster SF from AGN host galaxies. We quantify the
star-forming fraction, dust-obscured SF rates (SFRs), and specific-SFRs for
cluster galaxies as a function of cluster-centric radius and redshift. In good
agreement with previous studies, we find that SF in cluster galaxies at
is largely consistent with field galaxies at similar epochs,
indicating an era before significant quenching in the cluster cores
(Mpc). This is followed by a transition to lower SF activity as
environmental quenching dominates by . Enhanced SFRs are found in lower
mass () cluster galaxies. We
find significant variation in SF from cluster-to-cluster within our uniformly
selected sample, indicating that caution should be taken when evaluating
individual clusters. We examine AGN in clusters from , finding an
excess AGN fraction at , suggesting environmental triggering of AGN
during this epoch. We argue that our results a transition from field-like
to quenched SF, enhanced SF in lower mass galaxies in the cluster cores, and
excess AGN are consistent with a co-evolution between SF and AGN in
clusters and an increased merger rate in massive haloes at high redshift.Comment: 26 pages, 14 figures, 6 tables with appendix, accepted for
publication in the Astrophysical Journa
E-Manufacturing for product improvement at Red Bull technology
In Formula 1 racing, there is a strong motive for reducing component weight and thereby improving efficiency. This paper demonstrates the advantages e-Manufacturing brings to the production of hydraulic components. The DMLS production technique would enable weight reductions to be attained by its geometric design freedom coupled with this material’s attributes. The use of EOS Titanium Ti64 material for hydraulic components has been assessed by a hydraulic soak test at 25 MPa and no significant losses or failure occurred. The benefits to the efficiency of hydraulic flow have been measured using Particle Image Velocimetry (PIV) and the use of DMLS designed geometry has improved flow characteristics by 250% over that of the currently used techniques of manufacturing channels and bores
Assembly of the Red Sequence in Infrared-Selected Galaxy Clusters from the IRAC Shallow Cluster Survey
We present results for the assembly and star formation histories of massive
(~L*) red sequence galaxies in 11 spectroscopically confirmed,
infrared-selected galaxy clusters at 1.0 < z < 1.5, the precursors to
present-day massive clusters with M ~ 10^15 M_sun. Using rest-frame optical
photometry, we investigate evolution in the color and scatter of the red
sequence galaxy population, comparing with models of possible star formation
histories. In contrast to studies of central cluster galaxies at lower redshift
(z < 1), these data are clearly inconsistent with the continued evolution of
stars formed and assembled primarily at a single, much-earlier time.
Specifically, we find that the colors of massive cluster galaxies at z = 1.5
imply that the bulk of star formation occurred at z ~ 3, whereas by z = 1 their
colors imply formation at z ~ 2; therefore these galaxies exhibit approximately
the same luminosity-weighted stellar age at 1 < z < 1.5. This likely reflects
star formation that occurs over an extended period, the effects of significant
progenitor bias, or both. Our results generally indicate that massive cluster
galaxy populations began forming a significant mass of stars at z >~ 4,
contained some red spheroids by z ~ 1.5, and were actively assembling much of
their final mass during 1 < z < 2 in the form of younger stars. Qualitatively,
the slopes of the cluster color-magnitude relations are consistent with no
significant evolution relative to local clusters.Comment: 24 pages, 9 figures, accepted to Ap
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