8,270 research outputs found
Reducing transonic wind tunnel sting interference effects for concealed store release testing
Internal weapons bays are becoming increasingly common on aircraft for reasons of stealth and aerodynamic performance, and will be even more prevalent on coming generations of unmanned combat aerial vehicles (UCAVs). Wind tunnel testing of store releases to assess forces and moments for safety and clearance must be conducted with a store mounted to an angled strut rather than a conventional rear sting, to allow the full range of motion as the store “drops” from inside the aircraft. Interference from this strut can disrupt the flowfields and thus the reliability of moments obtained, and therefore an investigation was conducted to quantify the potential extent of discrepancies; original small-scale transonic wind tunnel testing was undertaken in a limited program which was supported by extensive numerical work. It was concluded that the precise geometry of the strut/store interface was of critical importance, with a typical design producing non-linear interference at high angles of attack. A simple improved design is proposed – making use of a blended interface and a more appropriate supercritical aerofoil strut cross section – yielding marked improvements in force and moment predictions
From theory to 'measurement' in complex interventions: methodological lessons from the development of an e-health normalisation instrument
<b>Background</b> Although empirical and theoretical understanding of processes of implementation in health care is advancing, translation of theory into structured measures that capture the complex interplay between interventions, individuals and context remain limited. This paper aimed to (1) describe the process and outcome of a project to develop a theory-based instrument for measuring implementation processes relating to e-health interventions; and (2) identify key issues and methodological challenges for advancing work in this field.<p></p>
<b>Methods</b> A 30-item instrument (Technology Adoption Readiness Scale (TARS)) for measuring normalisation processes in the context of e-health service interventions was developed on the basis on Normalization Process Theory (NPT). NPT focuses on how new practices become routinely embedded within social contexts. The instrument was pre-tested in two health care settings in which e-health (electronic facilitation of healthcare decision-making and practice) was used by health care professionals.<p></p>
<b>Results</b> The developed instrument was pre-tested in two professional samples (N = 46; N = 231). Ratings of items representing normalisation 'processes' were significantly related to staff members' perceptions of whether or not e-health had become 'routine'. Key methodological challenges are discussed in relation to: translating multi-component theoretical constructs into simple questions; developing and choosing appropriate outcome measures; conducting multiple-stakeholder assessments; instrument and question framing; and more general issues for instrument development in practice contexts.<p></p>
<b>Conclusions</b> To develop theory-derived measures of implementation process for progressing research in this field, four key recommendations are made relating to (1) greater attention to underlying theoretical assumptions and extent of translation work required; (2) the need for appropriate but flexible approaches to outcomes measurement; (3) representation of multiple perspectives and collaborative nature of work; and (4) emphasis on generic measurement approaches that can be flexibly tailored to particular contexts of study
Improving the normalization of complex interventions: measure development based on normalization process theory (NoMAD): study protocol
<b>Background</b> Understanding implementation processes is key to ensuring that complex interventions in healthcare are taken up in practice and thus maximize intended benefits for service provision and (ultimately) care to patients. Normalization Process Theory (NPT) provides a framework for understanding how a new intervention becomes part of normal practice. This study aims to develop and validate simple generic tools derived from NPT, to be used to improve the implementation of complex healthcare interventions.<p></p>
<b>Objectives</b> The objectives of this study are to: develop a set of NPT-based measures and formatively evaluate their use for identifying implementation problems and monitoring progress; conduct preliminary evaluation of these measures across a range of interventions and contexts, and identify factors that affect this process; explore the utility of these measures for predicting outcomes; and develop an online users’ manual for the measures.<p></p>
<b>Methods</b> A combination of qualitative (workshops, item development, user feedback, cognitive interviews) and quantitative (survey) methods will be used to develop NPT measures, and test the utility of the measures in six healthcare intervention settings.<p></p>
<b>Discussion</b> The measures developed in the study will be available for use by those involved in planning, implementing, and evaluating complex interventions in healthcare and have the potential to enhance the chances of their implementation, leading to sustained changes in working practices
SPT-CL J0205-5829: A z = 1.32 Evolved Massive Galaxy Cluster in the South Pole Telescope Sunyaev-Zel'dovich Effect Survey
The galaxy cluster SPT-CL J0205-5829 currently has the highest
spectroscopically-confirmed redshift, z=1.322, in the South Pole Telescope
Sunyaev-Zel'dovich (SPT-SZ) survey. XMM-Newton observations measure a
core-excluded temperature of Tx=8.7keV producing a mass estimate that is
consistent with the Sunyaev-Zel'dovich derived mass. The combined SZ and X-ray
mass estimate of M500=(4.9+/-0.8)e14 h_{70}^{-1} Msun makes it the most massive
known SZ-selected galaxy cluster at z>1.2 and the second most massive at z>1.
Using optical and infrared observations, we find that the brightest galaxies in
SPT-CL J0205-5829 are already well evolved by the time the universe was <5 Gyr
old, with stellar population ages >3 Gyr, and low rates of star formation
(<0.5Msun/yr). We find that, despite the high redshift and mass, the existence
of SPT-CL J0205-5829 is not surprising given a flat LambdaCDM cosmology with
Gaussian initial perturbations. The a priori chance of finding a cluster of
similar rarity (or rarer) in a survey the size of the 2500 deg^2 SPT-SZ survey
is 69%.Comment: 11 pages, 5 figures, submitted to Ap
Search for B-decay to Higgs bosons for Higgs boson masses between 50 and 210 MeV/c2
We use data from the Mark II experiment at PEP to search for the process B-->h0X for mh0 between 50 and 210 MeV/c2. No evidence for the Higgs boson is seen in this mass range. The limit obtained rules out the standard Higgs boson for masses between 70 and 210 MeV/c2 and significantly constrains extensions of the Higgs sector.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27719/1/0000107.pd
Ecological Invasion, Roughened Fronts, and a Competitor's Extreme Advance: Integrating Stochastic Spatial-Growth Models
Both community ecology and conservation biology seek further understanding of
factors governing the advance of an invasive species. We model biological
invasion as an individual-based, stochastic process on a two-dimensional
landscape. An ecologically superior invader and a resident species compete for
space preemptively. Our general model includes the basic contact process and a
variant of the Eden model as special cases. We employ the concept of a
"roughened" front to quantify effects of discreteness and stochasticity on
invasion; we emphasize the probability distribution of the front-runner's
relative position. That is, we analyze the location of the most advanced
invader as the extreme deviation about the front's mean position. We find that
a class of models with different assumptions about neighborhood interactions
exhibit universal characteristics. That is, key features of the invasion
dynamics span a class of models, independently of locally detailed demographic
rules. Our results integrate theories of invasive spatial growth and generate
novel hypotheses linking habitat or landscape size (length of the invading
front) to invasion velocity, and to the relative position of the most advanced
invader.Comment: The original publication is available at
www.springerlink.com/content/8528v8563r7u2742
IDCS J1433.2+3306: An IR-Selected Galaxy Cluster at z = 1.89
We report the discovery of an IR-selected galaxy cluster in the IRAC Distant
Cluster Survey (IDCS). New data from the Hubble Space Telescope
spectroscopically confirm IDCS J1433.2+3306 at z = 1.89 with robust
spectroscopic redshifts for seven members, two of which are based on the 4000
Angstrom break. Detected emission lines such as [OII] and Hbeta indicate star
formation rates of >20 solar masses per year for three galaxies within a 500
kpc projected radius of the cluster center. The cluster exhibits a red sequence
with a scatter and color indicative of a formation redshift z > 3.5. The
stellar age of the early-type galaxy population is approximately consistent
with those of clusters at lower redshift (1 < z < 1.5) suggesting that clusters
at these redshifts are experiencing ongoing or increasing star formation.Comment: Accepted in Ap
Recommended from our members
A Search for Dark Higgs Bosons
Recent astrophysical and terrestrial experiments have motivated the proposal
of a dark sector with GeV-scale gauge boson force carriers and new Higgs
bosons. We present a search for a dark Higgs boson using 516 fb-1 of data
collected with the BABAR detector. We do not observe a significant signal and
we set 90% confidence level upper limits on the product of the Standard
Model-dark sector mixing angle and the dark sector coupling constant.Comment: 7 pages, 5 postscript figures, published version with improved plots
for b/w printin
Measurement of the cross-section and charge asymmetry of bosons produced in proton-proton collisions at TeV with the ATLAS detector
This paper presents measurements of the and cross-sections and the associated charge asymmetry as a
function of the absolute pseudorapidity of the decay muon. The data were
collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with
the ATLAS experiment at the LHC and correspond to a total integrated luminosity
of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements
varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the
1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured
with an uncertainty between 0.002 and 0.003. The results are compared with
predictions based on next-to-next-to-leading-order calculations with various
parton distribution functions and have the sensitivity to discriminate between
them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables,
submitted to EPJC. All figures including auxiliary figures are available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13
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