11,413 research outputs found
Scaling dependence on time and distance in nonlinear fractional diffusion equations and possible applications to the water transport in soils
Recently, fractional derivatives have been employed to analyze various
systems in engineering, physics, finance and hidrology. For instance, they have
been used to investigate anomalous diffusion processes which are present in
different physical systems like: amorphous semicondutors, polymers, composite
heterogeneous films and porous media. They have also been used to calculate the
heat load intensity change in blast furnace walls, to solve problems of control
theory \ and dynamic problems of linear and nonlinear hereditary mechanics of
solids. In this work, we investigate the scaling properties related to the
nonlinear fractional diffusion equations and indicate the possibilities to the
applications of these equations to simulate the water transport in unsaturated
soils. Usually, the water transport in soils with anomalous diffusion, the
dependence of concentration on time and distance may be expressed in term of a
single variable given by In particular, for the
systems obey Fick's law and Richards' equation for water transport. We show
that a generalization of Richards' equation via fractional approach can
incorporate the above property.Comment: 9 page
The Radon Monitoring System in Daya Bay Reactor Neutrino Experiment
We developed a highly sensitive, reliable and portable automatic system
(H) to monitor the radon concentration of the underground experimental
halls of the Daya Bay Reactor Neutrino Experiment. H is able to measure
radon concentration with a statistical error less than 10\% in a 1-hour
measurement of dehumidified air (R.H. 5\% at 25C) with radon
concentration as low as 50 Bq/m. This is achieved by using a large radon
progeny collection chamber, semiconductor -particle detector with high
energy resolution, improved electronics and software. The integrated radon
monitoring system is highly customizable to operate in different run modes at
scheduled times and can be controlled remotely to sample radon in ambient air
or in water from the water pools where the antineutrino detectors are being
housed. The radon monitoring system has been running in the three experimental
halls of the Daya Bay Reactor Neutrino Experiment since November 2013
Automated Classification of 2000 Bright IRAS Sources
An Artificial Neural Network (ANN) has been employed using a supervised
back-propagation scheme to classify 2000 bright sources from the Calgary
database of IRAS (Infrared Astronomy Satellite) spectra in the wavelength
region of 8-23 microns. The data base has been classified into 17
pre-determined classes based on spectral morphology. We have been able to
classify more than 80 percent of the 2000 sources correctly at the first
instance. The speed and robustness of the scheme will allow us to classify the
whole of LRS database, containing more than 50,000 sources in the future.Comment: 26 pages, To appear in ApJS after July 200
Safety of short-term dual antiplatelet therapy after drug-eluting stents:An updated meta-analysis with direct and adjusted indirect comparison of randomized control trials
Background: Duration of dual antiplatelet therapy (DAPT) following drug-eluting stents (DES) remains controversial and is a topic of ongoing research. Methods: Direct and adjusted indirect comparisons of all the recent randomized control trials (RCTs) were performed to evaluate the safety of short-term versus long-term DAPT following DES. Results: 8 RCTs were identified and 7 (16,318 subjects) were included. 4 groups of 3 vs 12 months, 6 vs 12 months, 6 vs 24 months and 12 vs 24 months of DAPT were used for direct comparison. There was no significant difference in stent thrombosis, myocardial infarction (MI), stroke and revascularization, cardiovascular and all-cause mortality between the different durations in all 4 groups. Pooling trials of 3–6 months of DAPT against 12 months, we found a significant reduction in the risk of total bleeding (RR 0.61, 95% CI 0.43–0.87). Adjusted indirect comparison between 3 vs 6 months, 3 vs 24 months and 6 vs 24 month duration of DAPT showed no significant differences in risk of death or MI, or revascularization between 3 or 6 months and 24 months. However, 24 months of DAPT was associated with significantly more bleeding than 3 or 6 months. Conclusions: 3 to 6 months of DAPT following second generation DES and above is safe with no increased risk of thrombotic complications and mortality, and lower bleeding risk. However a tailored approach may be more appropriate for high-risk patients. Keywords: Percutaneous coronary intervention; Drug-eluting stent; Acute coronary syndrome; Dual antiplatelet treatment; Duration of therap
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