362 research outputs found
A Multiple Perspective Approach Towards the Assessment and Development of Expert Systems in Manufacturing. Volume 1
Current approaches to technology innovation often fail because they are conceived
and assessed from a single perspective or dimension. Thus, current considerations in
expert systems development are characterised by a strong focus upon the technology
and technical issues without a prior process of wider appraisal and technology
assessment. A central theme of this study is that the business, organisational and
human factors, which determine how effectively the technology will be used in
practice, must be an integral part of the assessment process. The thesis describes a
âmultiple perspective approachâ to technology assessment applied to expert systems
innovation in a large manufacturing organisation.
This research therefore embraces detailed technical, organisational and individual
perspectives of expert systems assessment and development and describes how each
perspective adds new concepts, methods and tools. In practice, this has meant
modelling activities and information flows in a two-site manufacturing organisation,
the identification of a variety of potential areas for expert systems development, the
narrowing down and selection of particular areas according to technical,
organisational, business and personal criteria, and the eventual design,
development, âoperationalisationâ and evaluation of a single application. This study
is placed in a wider context by complementary analyses of other manufacturing
users and suppliers of expert systems. The work aims to contribute towards an
understanding of expert systems innovation and to improved methodologies for
technology assessment and technology transfer.Ph
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Comprehensive Immune Monitoring of Clinical Trials to Advance Human Immunotherapy.
The success of immunotherapy has led to a myriad of clinical trials accompanied by efforts to gain mechanistic insight and identify predictive signatures for personalization. However, many immune monitoring technologies face investigator bias, missing unanticipated cellular responses in limited clinical material. We present here a mass cytometry (CyTOF) workflow for standardized, systems-level biomarker discovery in immunotherapy trials. To broadly enumerate immune cell identity and activity, we established and extensively assessed a reference panel of 33 antibodies to cover major cell subsets, simultaneously quantifying activation and immune checkpoint molecules in a single assay. This assay enumerates â„98% of peripheral immune cells with â„4 positively identifying antigens. Robustness and reproducibility are demonstrated on multiple samples types, across two research centers and by orthogonal measurements. Using automated analysis, we identify stratifying immune signatures in bone marrow transplantation-associated graft-versus-host disease. Together, this validated workflow ensures comprehensive immunophenotypic analysis and data comparability and will accelerate biomarker discovery
Shear dynamics in Bianchi I cosmologies with R^n-gravity
We give the equations governing the shear evolution in Bianchi spacetimes for
general f(R)-theories of gravity. We consider the case of R^n-gravity and
perform a detailed analysis of the dynamics in Bianchi I cosmologies which
exhibit local rotational symmetry. We find exact solutions and study their
behaviour and stability in terms of the values of the parameter n. In
particular, we found a set of cosmic histories in which the universe is
initially isotropic, then develops shear anisotropies which approaches a
constant value.Comment: 25 pages LaTeX, 6 figures. Revised to match the final version
accepted for publication in CQ
Hydrologically driven ecosystem processes determine the distribution and persistence of ecosystem-specialist predators under climate change
Climate change has the capacity to alter physical and biological ecosystem processes, jeopardizing the survival of associated species. This is a particular concern in cool, wet northern peatlands that could experience warmer, drier conditions. Here we show that climate, ecosystem processes and food chains combine to influence the population performance of species in British blanket bogs. Our peatland process model accurately predicts water-table depth, which predicts abundance of craneflies (keystone invertebrates), which in turn predicts observed abundances and population persistence of three ecosystem-specialist bird species that feed on craneflies during the breeding season. Climate change projections suggest that falling water tables could cause 56â81% declines in cranefly abundance and, hence, 15â51% reductions in the abundances of these birds by 2051â2080. We conclude that physical (precipitation, temperature and topography), biophysical (evapotranspiration and desiccation of invertebrates) and ecological (food chains) processes combine to determine the distributions and survival of ecosystem-specialist predators
Evolution of the Color-Magnitude Relation in Galaxy Clusters at z ~1 from the ACS Intermediate Redshift Cluster Survey
We apply detailed observations of the Color-Magnitude Relation (CMR) with the
ACS/HST to study galaxy evolution in eight clusters at z~1. The early-type red
sequence is well defined and elliptical and lenticular galaxies lie on similar
CMRs. We analyze CMR parameters as a function of redshift, galaxy properties
and cluster mass. For bright galaxies (M_B < -21mag), the CMR scatter of the
elliptical population in cluster cores is smaller than that of the S0
population, although the two become similar at faint magnitudes. While the
bright S0 population consistently shows larger scatter than the ellipticals,
the scatter of the latter increases in the peripheral cluster regions. If we
interpret these results as due to age differences, bright elliptical galaxies
in cluster cores are on average older than S0 galaxies and peripheral
elliptical galaxies (by about 0.5Gyr). CMR zero point, slope, and scatter in
the (U-B)_z=0 rest-frame show no significant evolution out to redshift z~1.3
nor significant dependence on cluster mass. Two of our clusters display CMR
zero points that are redder (by ~2sigma) than the average (U-B)_z=0 of our
sample. We also analyze the fraction of morphological early-type and late-type
galaxies on the red sequence. We find that, while in the majority of the
clusters most (80% to 90%) of the CMR population is composed of early-type
galaxies, in the highest redshift, low mass cluster of our sample, the CMR
late-type/early-type fractions are similar (~50%), with most of the late-type
population composed of galaxies classified as S0/a. This trend is not
correlated with the cluster's X-ray luminosity, nor with its velocity
dispersion, and could be a real evolution with redshift.Comment: ApJ, in press, 27 pages, 22 figure
CANDELS Observations of the Structural Properties and Evolution of Galaxies in a Cluster at z=1.62
We discuss the structural and morphological properties of galaxies in a
z=1.62 proto-cluster using near-IR imaging data from Hubble Space Telescope
Wide Field Camera 3 data of the Cosmic Assembly Near-IR Deep Extragalactic
Legacy Survey (CANDELS). The cluster galaxies exhibit a clear color-morphology
relation: galaxies with colors of quiescent stellar populations generally have
morphologies consistent with spheroids, and galaxies with colors consistent
with ongoing star formation have disk-like and irregular morphologies. The size
distribution of the quiescent cluster galaxies shows a deficit of compact (<
1kpc), massive galaxies compared to CANDELS field galaxies at z=1.6. As a
result the cluster quiescent galaxies have larger average effective sizes
compared to field galaxies at fixed mass at greater than 90% significance.
Combined with data from the literature, the size evolution of quiescent cluster
galaxies is relatively slow from z~1.6 to the present, growing as
(1+z)^(-0.6+/-0.1). If this result is generalizable, then it implies that
physical processes associated with the denser cluster region seems to have
caused accelerated size growth in quiescent galaxies prior to z=1.6 and slower
subsequent growth at z<1.6 compared to galaxies in the lower density field. The
quiescent cluster galaxies at z=1.6 have higher ellipticities compared to lower
redshift samples at fixed mass, and their surface-brightness profiles suggest
that they contain extended stellar disks. We argue the cluster galaxies require
dissipationless (i.e., gas-poor or "dry") mergers to reorganize the disk
material and to match the relations for ellipticity, stellar mass, size, and
color of early-type galaxies in z<1 clusters.Comment: Accepted for publication in ApJ. 14 pages in emulateapj format.
Replacement includes improvements from referee report, and updates and
additions to reference
Measuring with the ROSAT Deep Cluster Survey
We analyze the ROSAT Deep Cluster Survey (RDCS) to derive cosmological
constraints from the evolution of the cluster X-ray luminosity distribution.
The sample contains 103 galaxy clusters out to z=0.85 and flux-limit Flim=3
10^{-14} cgs (RDCS-3) in the [0.5-2.0] keV energy band, with a high-z extension
containing four clusters at 0.901 10^{-14} cgs (RDCS-1). Model
predictions for the cluster mass function are converted into the X-ray
luminosity function in two steps. First we convert mass into intra-cluster gas
temperature by assuming hydrostatic equilibrium. Then temperature is converted
into X-ray luminosity by using the most recent data on the Lx-T relation for
nearby and distant clusters. These include the Chandra data for seven distant
clusters at 0.57<z<1.27. From RDCS-3 we find \Omega_m=0.35+/-0.12 and
\sigma_8=0.66+/-0.06 for a spatially flat Universe with cosmological constant,
with no significant constraint on \Gamma . Even accounting for theoretical and
observational uncertainties in the mass/X-ray luminosity conversion, an
Einstein-de-Sitter model is always excluded at far more than the 3sigma level.Comment: 10 pages, 4 figures, to appear in Astrophysical Journa
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