The GRavitational lEnsing Accuracy Testing 2008 (GREAT08) Challenge focuses on a problem that is of crucial importance for future observations in cosmology. The shapes of distant galaxies can be used ...to determine the properties of dark energy and the nature of gravity, because light from those galaxies is bent by gravity from the intervening dark matter. The observed galaxy images appear distorted, although only slightly, and their shapes must be precisely disentangled from the effects of pixelisation, convolution and noise. The worldwide gravitational lensing community has made significant progress in techniques to measure these distortions via the Shear TEsting Program (STEP). Via STEP, we have run challenges within our own community, and come to recognise that this particular image analysis problem is ideally matched to experts in statistical inference, inverse problems and computational learning. Thus, in order to continue the progress seen in recent years, we are seeking an infusion of new ideas from these communities. This document details the GREAT08 Challenge for potential participants. Please visit http://www.great08challenge.info for the latest information.
A non-fimbrial adhesin (NFA-1) from the uropathogenic Escherichia coli strain 827 responsible for agglutination of human erythrocytes was cloned using the cos 4 cosmid vector. A clone was isolated ...which promoted haemagglutination and showed the same biological properties as the adhesin produced by the wild type strain. Both express adhesin at 37 degrees C, but not 18 degrees C nor in the presence of 1% glucose. Adhesin purified from the clone formed high molecular weight aggregates which were resolved to the 21 K dalton subunit protein seen in the wild type strain on denaturation. Binding to human kidney cells by the clone and the wild type E. coli, from which the genes were cloned, were compared in an ELISA assay and shown to be the same. The genes for the adhesin were isolated on a 15.5 kilobase BamHI-EcoRI fragment which was subjected to gamma delta mutagenesis. The NFA-1 operon was localised to a 6.5kb region of this fragment.
Mon.Not.Roy.Astron.Soc.376:13-38,2007 The Shear TEsting Programme (STEP) is a collaborative project to improve the
accuracy and reliability of weak lensing measurement, in preparation for the
next ...generation of wide-field surveys. We review sixteen current and emerging
shear measurement methods in a common language, and assess their performance by
running them (blindly) on simulated images that contain a known shear signal.
We determine the common features of algorithms that most successfully recover
the input parameters. We achieve previously unattained discriminatory precision
in our analysis, via a combination of more extensive simulations, and pairs of
galaxy images that have been rotated with respect to each other, thus removing
noise from their intrinsic ellipticities. The robustness of our simulation
approach is also confirmed by testing the relative calibration of methods on
real data.
Weak lensing measurement has improved since the first STEP paper. Several
methods now consistently achieve better than 2% precision, and are still being
developed. However, the simulations can now distinguish all methods from
perfect performance. Our main concern continues to be the potential for a
multiplicative shear calibration bias: not least because this can not be
internally calibrated with real data. We determine which galaxy populations are
responsible and, by adjusting the simulated observing conditions, we also
investigate the effects of instrumental and atmospheric parameters. We have
isolated several previously unrecognised aspects of galaxy shape measurement,
in which focussed development could provide further progress towards the
sub-percent level of precision desired for future surveys.
ABRIDGED
A descriptive assessment of environmental variables influencing patterns of staff communication with people living in three community-based residential facilities supporting persons with disabilities ...was presented. Each of the 16 participating staff persons was observed for 2 hours, and all resident-directed communication behaviors were coded according to staff person, activity context, and resident. Statistical analyses were performed examining frequencies of interaction across these variables. Frequencies of communication were found to differ across activities and residents (communicative partners), but not staff persons or homes. Directions for future research and clinical implications are given, including the development of a model of staff performance and the creation of self-reinforcing social communities in residential settings for persons with disabilities.
The Shear TEsting Programme (STEP) is a collaborative project to improve the accuracy and reliability of weak lensing measurement, in preparation for the next generation of wide-field surveys. We ...review sixteen current and emerging shear measurement methods in a common language, and assess their performance by running them (blindly) on simulated images that contain a known shear signal. We determine the common features of algorithms that most successfully recover the input parameters. We achieve previously unattained discriminatory precision in our analysis, via a combination of more extensive simulations, and pairs of galaxy images that have been rotated with respect to each other, thus removing noise from their intrinsic ellipticities. The robustness of our simulation approach is also confirmed by testing the relative calibration of methods on real data. Weak lensing measurement has improved since the first STEP paper. Several methods now consistently achieve better than 2% precision, and are still being developed. However, the simulations can now distinguish all methods from perfect performance. Our main concern continues to be the potential for a multiplicative shear calibration bias: not least because this can not be internally calibrated with real data. We determine which galaxy populations are responsible and, by adjusting the simulated observing conditions, we also investigate the effects of instrumental and atmospheric parameters. We have isolated several previously unrecognised aspects of galaxy shape measurement, in which focussed development could provide further progress towards the sub-percent level of precision desired for future surveys. ABRIDGED
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