333 research outputs found
Machine Learning Based Auto-tuning for Enhanced OpenCL Performance Portability
Heterogeneous computing, which combines devices with different architectures,
is rising in popularity, and promises increased performance combined with
reduced energy consumption. OpenCL has been proposed as a standard for
programing such systems, and offers functional portability. It does, however,
suffer from poor performance portability, code tuned for one device must be
re-tuned to achieve good performance on another device. In this paper, we use
machine learning-based auto-tuning to address this problem. Benchmarks are run
on a random subset of the entire tuning parameter configuration space, and the
results are used to build an artificial neural network based model. The model
can then be used to find interesting parts of the parameter space for further
search. We evaluate our method with different benchmarks, on several devices,
including an Intel i7 3770 CPU, an Nvidia K40 GPU and an AMD Radeon HD 7970
GPU. Our model achieves a mean relative error as low as 6.1%, and is able to
find configurations as little as 1.3% worse than the global minimum.Comment: This is a pre-print version an article to be published in the
Proceedings of the 2015 IEEE International Parallel and Distributed
Processing Symposium Workshops (IPDPSW). For personal use onl
Isospin Dependence in the Odd-Even Staggering of Nuclear Binding Energies
The FRS-ESR facility at GSI provides unique conditions for precision
measurements of large areas on the nuclear mass surface in a single experiment.
Values for masses of 604 neutron-deficient nuclides (30<=Z<=92) were obtained
with a typical uncertainty of 30 microunits. The masses of 114 nuclides were
determined for the first time. The odd-even staggering (OES) of nuclear masses
was systematically investigated for isotopic chains between the proton shell
closures at Z=50 and Z=82. The results were compared with predictions of modern
nuclear models. The comparison revealed that the measured trend of OES is not
reproduced by the theories fitted to masses only. The spectral pairing gaps
extracted from models adjusted to both masses, and density related observables
of nuclei agree better with the experimental data.Comment: Physics Review Letters 95 (2005) 042501
http://link.aps.org/abstract/PRL/v95/e04250
Present and Future Experiments with Stored Exotic Nuclei at Relativistic Energies
Recent progress is presented from experiments on masses and lifetimes of bare
and few-electron exotic nuclei at GSI.Comment: Proceedings of International Conference on "Frontiers in Nuclear
Structure, Astrophysics and Reactions", Kos, Greece, September 12-17, 200
Comparison of hip fracture incidence and trends between Germany and Austria 1995-2004: An epidemiological study
Mann E, Meyer G, Haastert B, Icks A. Comparison of hip fracture incidence and trends between Germany and Austria 1995-2004: an epidemiological study. BMC Public Health. 2010;10(1): 46.Background Several studies evaluated variations in hip fracture incidences, as well as trends of the hip fracture incidences. Comparisons of trends are lacking so far. We compared the incidence rates and, in particular, its trends between Austria and Germany 1995 to 2004 analysing national hospital discharge diagnosis register data. Methods Annual frequencies of hip fractures and corresponding incidences per 100,000 person years were estimated, overall and stratified for sex and age, assuming Poisson distribution. Multiple Poisson regression models including country and calendar year, age and sex were used to analyse differences in incidence and trend. The difference of annual changes between the two countries was explored using an interaction term (calender year * country). Results Overall, the increase of hip fracture risk was 1.31 fold higher (95% CI 1.29-1.34) in Austria compared to Germany, adjusted for age, sex, and calendar year. The risk increase was comparable for both sexes (males: RR 1.35 (1.32-1.37), females: RR 1.31 (1.29-1.33)). Hip fracture trend from 1995 to 2004 indicates an increase in both countries without a statistically significant difference between Austria and Germany (interaction term: p = 0.67). Conclusion In this study comparing hip fracture incidences and its trend using pooled data, the incidence in Austria was 30% higher compared to its neighbouring country Germany. For both countries a similar increasing trend of hip fracture incidence over the 10-year study period was calculated. The results need confirmation by other studies
Effect of urbanization on bone mineral density: A Thai epidemiological study
BACKGROUND: The incidence of fractures in rural populations is lower than in urban populations, although the reason for this difference is unclear. This cross-sectional study was designed to examine the difference in bone mineral density (BMD), a primary predictor of fracture risk, between urban and rural Thai populations. METHODS: Femoral neck and lumbar spine BMD was measured by dual-energy X-ray absorptiometry (GE Lunar, Madison, WI) in 411 urban and 436 rural subjects (340 men and 507 women), aged between 20 and 84 years. Body mass index (BMI) was calculated from weight and height. RESULTS: After adjusting for age and body weight in an analysis of covariance model, femoral neck BMD in rural men and women was significantly higher than those in urban men and women (P < 0.001), but the difference was not observed at the lumbar spine. After stratifying by sex, age group, and BMI category, the urban-rural difference in femoral neck BMD became more pronounced in men and women aged <50 years and with BMI ≥ 25 kg/m(2). CONCLUSIONS: These data suggest that femoral neck BMD in rural men and women was higher than their counterparts in urban areas. This difference could potentially explain part of the urban-rural difference in fracture incidence
- …