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A discussion of practices for enhancing diversity in software designs
How bilingual experience and executive control influence development in language control among bilingual children
A GPU-based survey for millisecond radio transients using ARTEMIS
Astrophysical radio transients are excellent probes of extreme physical
processes originating from compact sources within our Galaxy and beyond. Radio
frequency signals emitted from these objects provide a means to study the
intervening medium through which they travel. Next generation radio telescopes
are designed to explore the vast unexplored parameter space of high time
resolution astronomy, but require High Performance Computing (HPC) solutions to
process the enormous volumes of data that are produced by these telescopes. We
have developed a combined software /hardware solution (code named ARTEMIS) for
real-time searches for millisecond radio transients, which uses GPU technology
to remove interstellar dispersion and detect millisecond radio bursts from
astronomical sources in real-time. Here we present an introduction to ARTEMIS.
We give a brief overview of the software pipeline, then focus specifically on
the intricacies of performing incoherent de-dispersion. We present results from
two brute-force algorithms. The first is a GPU based algorithm, designed to
exploit the L1 cache of the NVIDIA Fermi GPU. Our second algorithm is CPU based
and exploits the new AVX units in Intel Sandy Bridge CPUs.Comment: 4 pages, 7 figures. To appear in the proceedings of ADASS XXI, ed.
P.Ballester and D.Egret, ASP Conf. Se
Numerical Investigation of the Sliding Contact of Tire Rubber Material Due to a Blade Sliding Indentation
High Spatial Resolution Fast-Neutron Imaging Detectors for Pulsed Fast-Neutron Transmission Spectroscopy
Two generations of a novel detector for high-resolution transmission imaging
and spectrometry of fast-neutrons are presented. These devices are based on a
hydrogenous fiber scintillator screen and single- or multiple-gated intensified
camera systems (ICCD). This detector is designed for energy-selective neutron
radiography with nanosecond-pulsed broad-energy (1 - 10 MeV) neutron beams.
Utilizing the Time-of-Flight (TOF) method, such a detector is capable of
simultaneously capturing several images, each at a different neutron energy
(TOF). In addition, a gamma-ray image can also be simultaneously registered,
allowing combined neutron/gamma inspection of objects. This permits combining
the sensitivity of the fast-neutron resonance method to low-Z elements with
that of gamma radiography to high-Z materials.Comment: Also published in JINST:
http://www.iop.org/EJ/abstract/1748-0221/4/05/P0501
Dynamic inundation simulation of storm water interaction between sewer system and overland flows
Copyright © 2002 Taylor & FrancisThis is the Author's Accepted Manuscript of an article published in the Journal of the Chinese Institute of Engineers (2002), available online at: http://www.tandfonline.com/10.1080/02533839.2002.9670691An improved urban inundation model, coupling a 2D nonâinertia overland flow model with a storm water management model, is adopted to simulate inundation in urban areas. The model computes, not only the overland runoff and the water overflow through manholes where surface runoff exceeds the capacity of storm sewers, but also the bidirectional flow interactions between sewers and overland runoff. The model was verified by a typhoon event in Nov. 2000, which resulted in serious inundation in the Mucha area of Taipei City. The result shows that the present model indeed improves simulation accuracy over the earlier model, and can be used to provide a more reliable flood mitigation design
Study of low energy Si and Cs implantation induced amorphization effects in Si(100)
The damage growth and surface modifications in Si(100), induced by 25 keV
Si cluster ions, as a function of fluence, , has been studied using
atomic force microscopy (AFM) and channeling Rutherford backscattering
spectrometry (CRBS). CRBS results indicate a nonlinear growth in damage from
which it has been possible to get a threshold fluence, , for
amorphization as ions-cm. For below ,
a growth in damage as well as surface roughness has been observed. At a
of ions-cm, damage saturation coupled with a much
reduced surface roughness has been found. In this case a power spectrum
analysis of AFM data showed a significant drop, in spectral density, as
compared to the same obtained for a fluence, . This drop,
together with damage saturation, can be correlated with a transition to a
stress relaxed amorphous phase. Irradiation with similar mass Cs ions, at
the same energy and fluence, has been found to result in a reduced accumulation
of defects in the near surface region leading to reduced surface features.Comment: 7 pages, 4 figure
Use of the bootstrap in analysing cost data from cluster randomised trials: some simulation results
BACKGROUND: This work has investigated under what conditions confidence intervals around the differences in mean costs from a cluster RCT are suitable for estimation using a commonly used cluster-adjusted bootstrap in preference to methods that utilise the Huber-White robust estimator of variance. The bootstrap's main advantage is in dealing with skewed data, which often characterise patient costs. However, it is insufficiently well recognised that one method of adjusting the bootstrap to deal with clustered data is only valid in large samples. In particular, the requirement that the number of clusters randomised should be large would not be satisfied in many cluster RCTs performed to date. METHODS: The performances of confidence intervals for simple differences in mean costs utilising a robust (cluster-adjusted) standard error and from two cluster-adjusted bootstrap procedures were compared in terms of confidence interval coverage in a large number of simulations. Parameters varied included the intracluster correlation coefficient, the sample size and the distributions used to generate the data. RESULTS: The bootstrap's advantage in dealing with skewed data was found to be outweighed by its poor confidence interval coverage when the number of clusters was at the level frequently found in cluster RCTs in practice. Simulations showed that confidence intervals based on robust methods of standard error estimation achieved coverage rates between 93.5% and 94.8% for a 95% nominal level whereas those for the bootstrap ranged between 86.4% and 93.8%. CONCLUSION: In general, 24 clusters per treatment arm is probably the minimum number for which one would even begin to consider the bootstrap in preference to traditional robust methods, for the parameter combinations investigated here. At least this number of clusters and extremely skewed data would be necessary for the bootstrap to be considered in favour of the robust method. There is a need for further investigation of more complex bootstrap procedures if economic data from cluster RCTs are to be analysed appropriately
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