122 research outputs found
The University Defence Research Collaboration In Signal Processing: 2013-2018
Signal processing is an enabling technology crucial to all areas
of defence and security. It is called for whenever humans and
autonomous systems are required to interpret data (i.e. the signal)
output from sensors. This leads to the production of the
intelligence on which military outcomes depend. Signal processing
should be timely, accurate and suited to the decisions
to be made. When performed well it is critical, battle-winning
and probably the most important weapon which youâve never
heard of.
With the plethora of sensors and data sources that are
emerging in the future network-enabled battlespace, sensing
is becoming ubiquitous. This makes signal processing more
complicated but also brings great opportunities.
The second phase of the University Defence Research Collaboration
in Signal Processing was set up to meet these complex
problems head-on while taking advantage of the opportunities.
Its unique structure combines two multi-disciplinary
academic consortia, in which many researchers can approach
different aspects of a problem, with baked-in industrial collaboration
enabling early commercial exploitation.
This phase of the UDRC will have been running for 5 years
by the time it completes in March 2018, with remarkable results.
This book aims to present those accomplishments and
advances in a style accessible to stakeholders, collaborators and
exploiters
Obesity dependent metabolic signatures associated with nonalcoholic fatty liver disease progression
Our understanding of the mechanisms by which nonalcoholic fatty liver disease (NAFLD) progresses from simple steatosis to steatohepatitis (NASH) is still very limited. Despite the growing number of studies linking the disease with altered serum metabolite levels, an obstacle to the development of metabolome-based NAFLD predictors has been the lack of large cohort data
from biopsy-proven patients matched for key metabolic features such as obesity. We studied 467 biopsied individuals with normal liver histology (n=90) or diagnosed with NAFLD (steatosis, n=246; NASH, n=131), randomly divided into estimation (80% of all patients) and validation (20% of all patients) groups. Qualitative determinations of 540 serum metabolite variables were performed using ultra-performance liquid chromatography coupled to mass spectrometry (UPLCMS). The metabolic profile was dependent on patient body-mass index (BMI), suggesting that the
NAFLD pathogenesis mechanism may be quite different depending on an individualâs level of obesity. A BMI-stratified multivariate model based on the NAFLD serum metabolic profile was used to separate patients with and without NASH. The area under the receiver operating characteristic curve was 0.87 in the estimation and 0.85 in the validation group. The cutoff (0.54)
corresponding to maximum average diagnostic accuracy (0.82) predicted NASH with a sensitivity of 0.71 and a specificity of 0.92 (negative/positive predictive values = 0.82/0.84). The present data, indicating that a BMI-dependent serum metabolic profile may be able to reliably distinguish NASH from steatosis patients, have significant implications for the development of
NASH biomarkers and potential novel targets for therapeutic intervention
The Gemini/HST Cluster Project: Structural and Photometric Properties of Galaxies in Three z =0.28-0.89 Clusters
We present the data processing and analysis techniques we are using to
determine structural and photometric properties of galaxies in our Gemini/HST
Galaxy Cluster Project sample. The goal of this study is to understand cluster
galaxy evolution in terms of scaling relations and structural properties of
cluster galaxies at redshifts 0.15 < z < 1.0. To derive parameters such as
total magnitude, half-light radius, effective surface brightness, and Sersic n,
we fit r^{1/4} law and Sersic function 2-D surface brightness profiles to each
of the galaxies in our sample. Using simulated galaxies, we test how the
assumed profile affects the derived parameters and how the uncertainties affect
our Fundamental Plane results. We find that while fitting galaxies which have
Sersic index n < 4 with r^{1/4} law profiles systematically overestimates the
galaxy radius and flux, the combination of profile parameters that enter the
Fundamental Plane has uncertainties that are small. Average systematic offsets
and associated random uncertainties in magnitude and log r_e for n > 2 galaxies
fitted with r^{1/4} law profiles are -0.1+-0.3 and 0.1+-0.2 respectively. The
combination of effective radius and surface brightness, log r_e - \beta log
_e, that enters the Fundamental Plane produces offsets smaller than
-0.02+-0.10. This systematic error is insignificant and independent of galaxy
magnitude or size. A catalog of photometry and surface brightness profile
parameters is presented for three of the clusters in our sample, RX
J0142.0+2131, RX J0152.7-1357, and RX J1226.9+3332 at redshifts 0.28, 0.83, and
0.89 respectively.Comment: 31 pages, 15 figure
RXJ0152.7-1357: Stellar populations in an X-ray luminous galaxy cluster at z=0.83
We present a study of the stellar populations of galaxies in the cluster
RXJ0152.7-1357 at a redshift of 0.83. The study is based on new high S/N
spectroscopy of 29 cluster members covering the wavelength range 5000-10000A as
well as r'i'z' photometry of the cluster. The scaling relations between
velocity dispersions, luminosities and Balmer line strengths appear to be in
agreement with pure passive evolution of the stellar populations with a
formation redshift z=4. However, the strengths of the D4000 indices and the
metal indices do not support this interpretation. Compared to z=0, the metal
indices (C4668, Fe4383, CN3883, G4300 and CN2) show that at least half of the
non-emission line galaxies in RXJ0152.7-1357 have [alpha/Fe] of 0.2 dex higher,
and about half of the galaxies have significantly lower metal content. The
differences in stellar populations of the galaxies are associated with the
location of the galaxies relative to the X-ray emission. The galaxies with weak
C4668 and G4300, as well as galaxies with weak [OII] emission, are located in
areas of low X-ray luminosity. It is possible that these galaxies are
experiencing the effect of the cluster merger taking place in RXJ0152.7-1357 as
(short) episodes of star formation, while the galaxies in the cores of the
X-ray sub-clumps are unaffected by the merger. The spectroscopy of the
RXJ0152.7-1357 galaxies shows for the first time galaxies in a rich cluster at
intermediate redshift that cannot evolve passively into the present day galaxy
population in rich clusters. Additional physical processes may be at work and
we speculate that merging with infalling (disk) galaxies in which stars have
formed over an extended period might produce the required reduction in
[alpha/Fe]. (abridged)Comment: Accepted for publication in Astronomical Journal, 39 pages, uses
emulateapj.cls, 18 figures. High resolution color figures available by e-mail
request to the first autho
The Fundamental Plane in RX J0142.0+2131: a galaxy cluster merger at z=0.28
We present the Fundamental Plane (FP) in the z = 0.28 cluster of galaxies RX
J0142.0+2131. There is no evidence for a difference in the slope of the FP when
compared with the Coma cluster, although the internal scatter is larger. On
average, stellar populations in RX J0142.0+2131 have rest-frame V-band
mass-to-light ratios (M/L_V) 0.29+-0.03 dex lower than in Coma. This is
significantly lower than expected for a passively-evolving cluster formed at
z_f=2. Lenticular galaxies have lower average M/L_V and a distribution of M/L_V
with larger scatter than ellipticals. Lower mass-to-light ratios are not due to
recent star formation: our previous spectroscopic observations of RX
J0142.0+2131 E/S0 galaxies showed no evidence for significant star-formation
within the past ~4 Gyr. However, cluster members have enhanced alpha-element
abundance ratios, which may act to decrease M/L_V. The increased scatter in the
RX J0142.0+2131 FP reflects a large scatter in M/L_V implying that galaxies
have undergone bursts of star formation over a range of epochs. The seven
easternmost cluster galaxies, including the second brightest member, have M/L_V
consistent with passive evolution and z_f = 2. We speculate that RX
J0142.0+2131 is a cluster-cluster merger where the galaxies to the east are yet
to fall into the main cluster body or have not experienced star formation as a
result of the merger.Comment: 4 pages, 2 figures, accepted for publication in ApJ Letter
RXJ0142.0+2131: I. The galaxy content of an X-ray-luminous galaxy cluster at z=0.28
We present a photometric and spectroscopic study of stellar populations in
the X-ray-luminous cluster of galaxies RXJ0142.0+2131 at z=0.280. This paper
analyses the results of high signal-to-noise spectroscopy, as well as g'-, r'-,
and i'-band imaging, using the Gemini Multi-Object Spectrograph on Gemini
North. Of 43 spectroscopic targets, we find 30 cluster members over a range in
color. Central velocity dispersions and absorption-line strengths for lines in
the range 3700A < lambda_rest < 5800A are derived for cluster members, and are
compared with a low-redshift sample of cluster galaxies, and single stellar
population (SSP) models. We use a combination of these indicators to estimate
luminosity-weighted mean ages, metallicities ([M/H]), and alpha-element
abundance ratios ([alpha/Fe]).
RXJ0142.0+2131 is a relatively poor cluster and lacks galaxies with high
central velocity dispersions. Although the red sequence and the Faber-Jackson
relation are consistent with pure passive evolution of the early-type
population with a formation redshift of z_form = 2, the strengths of the 4000A
break and scaling relations between metal line indices and velocity dispersion
reject this model with high significance. By inverting SSP models for the
Hbeta_G, Mgb, and line indices, we calculate that, at a given velocity
dispersion and metallicity, galaxies in RXJ0142.0+2131 have luminosity-weighted
mean ages 0.14 +- 0.07 dex older than the low-redshift sample. We also find
that [alpha/Fe] in stellar populations in RXJ0142.0+2131 is 0.14 +- 0.03
greater than at low redshift. All scaling relations are consistent with these
estimated offsets. (abridged)Comment: AJ, accepted. 31 pages, 13 figures, uses emulateapj.cls.
High-resolution figures available on request from first autho
Tunable-filter imaging of quasar fields at z~1. I. A cluster around MRC B0450-221
Using a combination of multicolour broad- and narrow-band imaging techniques
and follow-up spectroscopy, we have detected an overdensity of galaxies in the
field of quasar MRC B0450-221, whose properties are consistent with a cluster
at the quasar redshift z=0.9. An excess of red galaxies (V-I>2.2, I-K'>3.8) is
evident within 1' of the quasar, with the colours expected for galaxies at
z=0.9 that have evolved passively for 3 Gyr or more. A number of line-emitting
galaxies (nine candidates with equivalent widths EW>70A) are also detected in
the field using the TAURUS Tunable Filter (TTF). Three have been confirmed
spectroscopically to indeed lie at z=0.9. The TTF candidates with the strongest
[O II] line emission cluster in a group which lies 200-700 kpc away from the
quasar and the red galaxy excess, and therefore most likely on the outskirts of
the cluster. These observations are the first in a series probing quasar
environments at z~1 with TTF.Comment: Accepted for publication in AJ. 25 pages, 24 figs (large files in jpg
or gif format), uses emulateapj.st
Neurobehavioral Deficits and Increased Blood Pressure in School-Age Children Prenatally Exposed to Pesticides
Background: The long-term neurotoxicity risks caused by prenatal exposures to pesticides are unclear, but a previous pilot study of Ecuadorian school children suggested that blood pressure and visuospatial processing may be vulnerable. Objectives: In northern Ecuador, where floriculture is intensive and relies on female employment, we carried out an intensive cross-sectional study to assess childrenâs neurobehavioral functions at 6â8 years of age. Methods: We examined all 87 children attending two grades in the local public school with an expanded battery of neurobehavioral tests. Information on pesticide exposure during the index pregnancy was obtained from maternal interview. The childrenâs current pesticide exposure was assessed from the urinary excretion of organophosphate metabolites and erythrocyte acetylcholine esterase activity. Results: Of 84 eligible participants, 35 were exposed to pesticides during pregnancy via maternal occupational exposure, and 23 had indirect exposure from paternal work. Twenty-two children had detectable current exposure irrespective of their prenatal exposure status. Only children with prenatal exposure from maternal greenhouse work showed consistent deficits after covariate adjustment, which included stunting and socioeconomic variables. Exposure-related deficits were the strongest for motor speed (Finger Tapping Task), motor coordination (Santa Ana Form Board), visuospatial performance (Stanford-Binet Copying Test), and visual memory (Stanford-Binet Copying Recall Test). These associations corresponded to a developmental delay of 1.5â2 years. Prenatal pesticide exposure was also significantly associated with an average increase of 3.6 mmHg in systolic blood pressure and a slight decrease in body mass index of 1.1 kg/m2. Inclusion of the pilot data strengthened these results. Conclusions: These findings support the notion that prenatal exposure to pesticidesâat levels not producing adverse health outcomes in the motherâcan cause lasting adverse effects on brain development in children. Pesticide exposure therefore may contribute to a âsilent pandemicâ of developmental neurotoxicity
Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial
Background
Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy
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