3,690 research outputs found
Direct neutron capture of 48Ca at kT = 52 keV
The neutron capture cross section of 48Ca was measured relative to the known
gold cross section at kT = 52 keV using the fast cyclic activation technique.
The experiment was performed at the Van-de-Graaff accelerator, Universitaet
Tuebingen. The new experimental result is in good agreement with a calculation
using the direct capture model. The 1/v behaviour of the capture cross section
at thermonuclear energies is confirmed, and the adopted reaction rate which is
based on several previous experimental investigations remains unchanged.Comment: 9 pages (uses Revtex), 2 postscript figures, accepted for publication
as Brief Report in Phys. Rev.
Absence of low-temperature dependence of the decay of 7Be and 198Au in metallic hosts
The electron-capture (EC) decay rate of 7Be in metallic Cu host and the
beta-decay rate of 198Au in the host alloy Al-Au have been measured
simultaneously at several temperatures, ranging from 0.350 K to 293 K. No
difference of the half-life of 198Au between 12.5 K and 293 K is observed to a
precision of 0.1%. By utilizing the special characteristics of our
double-source assembly, possible geometrical effects that influence the
individual rates could be eliminated. The ratio of 7Be to 198Au activity thus
obtained also remains constant for this temperatures range to the experimental
precision of 0.15(0.16)%. The resulting null temperature dependence is
discussed in terms of the inadequacy of the often-used Debye-Huckel model for
such measurements.Comment: Four pages, three figures. Accepted for publication in Phys. Rev. C
(Rapd Communications
Study of the dependence of 198Au half-life on source geometry
We report the results of an experiment to determine whether the half-life of
\Au{198} depends on the shape of the source. This study was motivated by recent
suggestions that nuclear decay rates may be affected by solar activity, perhaps
arising from solar neutrinos. If this were the case then the -decay
rates, or half-lives, of a thin foil sample and a spherical sample of gold of
the same mass and activity could be different. We find for \Au{198},
, where
is the mean half-life. The maximum neutrino flux at the sample in our
experiments was several times greater than the flux of solar neutrinos at the
surface of the Earth. We show that this increase in flux leads to a significant
improvement in the limits that can be inferred on a possible solar contribution
to nuclear decays.Comment: 5 pages, 1 figur
Aerodynamic characteristics of a large-scale hybrid upper surface blown flap model having four engines
Data are presented from an investigation of the aerodynamic characteristics of large-scale wind tunnel aircraft model that utilized a hybrid-upper surface blown flap to augment lift. The hybrid concept of this investigation used a portion of the turbofan exhaust air for blowing over the trailing edge flap to provide boundary layer control. The model, tested in the Ames 40- by 80-foot Wind Tunnel, had a 27.5 deg swept wing of aspect ratio 8 and 4 turbofan engines mounted on the upper surface of the wing. The lift of the model was augmented by turbofan exhaust impingement on the wind upper-surface and flap system. Results were obtained for three flap deflections, for some variation of engine nozzle configuration and for jet thrust coefficients from 0 to 3.0. Six-component longitudinal and lateral data are presented with four engine operation and with the critical engine out. In addition, a limited number of cross-plots of the data are presented. All of the tests were made with a downwash rake installed instead of a horizontal tail. Some of these downwash data are also presented
g factor of lithiumlike silicon 28Si11+
The g factor of lithiumlike 28Si11+ has been measured in a triple-Penning
trap with a relative uncertainty of 1.1x10^{-9} to be g_exp=2.0008898899(21).
The theoretical prediction for this value was calculated to be
g_th=2.000889909(51) improving the accuracy to 2.5x10^{-8} due to the first
rigorous evaluation of the two-photon exchange correction. The measured value
is in excellent agreement with the state-of-the-art theoretical prediction and
yields the most stringent test of bound-state QED for the g factor of the
1s^22s state and the relativistic many-electron calculations in a magnetic
field
Effect of injection depth of digestate liquid fraction on soil carbon dioxide emission and maize biomass production
The aim of this study was to evaluate, in open field conditions, the effect of injection depth of digestate liquid fraction (10 cm, 25 cm and 35 cm) in clay loam soil, on CO2 emission. An un-amended soil was considered as control. The study was performed in 2014 on a farm located in Terrasa Padovana, Veneto region (Italy) distributing digestate before maize sowing. Digestate injection determined a high soil CO2 emission in the first
hour after application, followed by a progressive reduction in as early as 24 h, reaching significantly lower values, similar to those measured in the un-amended control, after 48 h. Gas emissions measured 1 h
after digestate application decreased as injection depth increased with significantly higher emission values in the 10 cm treatment (median value 23.7 g CO2 m\u20132 h\u20131) than in the 35 cm one (median value 2.5 g
CO2 m\u20132 h\u20131). In the 3 days between digestate distribution and maize sowing, soil CO2 emission was significantly higher in the amended treatments than un-amended one, with median values of 1.53 g CO2
m\u20132 h\u20131 and 0.46 g CO2 m\u20132 h\u20131 respectively. During maize growing season, no significant soil CO2 emission difference was monitored among treatments, with a median value of 0.33 g CO2 m\u20132 h\u20131. Digestate application significantly improved maize aboveground dry biomass with an average yield of 22.0 Mg ha\u20131 and 16.2 Mg ha\u20131 in amended and un-amended plots, respectively, due to the different amount of nutrients supplied
Department of Vocational Rehabilitation, FY 2008
These Facts sheets have been developed to provide a multitude of information about executive branch agencies/departments on a single sheet of paper. The Facts provides general information, contact information, workforce data, leave & benefits information, and affirmative action data. This is the most recent update of information for the fiscal year 2007
Simple High-performance Liquid Chromatographic Method for the Determination of Acyclovir in Pharmaceuticals
An assay method for the determination of acyclovir from pharmaceutical preparations has been developed for assessment of product quality utilising high-performance liquid chromatography. The chromatographic conditions comprised a reversed-phase C18 column (250×4.6 mm i.d.) with a mobile phase of acetonitrile-20 mmol l−1 aqueous ammonium acetate buffer of pH 4.5 (40:60). The flow rate was 0.8 ml min−1 and UV detection was used at 250 nm. Calibration graph was linear in the range 1.98–59.4 μg ml−1. The method has been validated according to current guidelines including assay of pharmacopoeial standard tablets. Recoveries ranged from 96.64 to 99.53%. The exipients present in the tablets did not interfere with the method
Creating Fair Models of Atherosclerotic Cardiovascular Disease Risk
Guidelines for the management of atherosclerotic cardiovascular disease
(ASCVD) recommend the use of risk stratification models to identify patients
most likely to benefit from cholesterol-lowering and other therapies. These
models have differential performance across race and gender groups with
inconsistent behavior across studies, potentially resulting in an inequitable
distribution of beneficial therapy. In this work, we leverage adversarial
learning and a large observational cohort extracted from electronic health
records (EHRs) to develop a "fair" ASCVD risk prediction model with reduced
variability in error rates across groups. We empirically demonstrate that our
approach is capable of aligning the distribution of risk predictions
conditioned on the outcome across several groups simultaneously for models
built from high-dimensional EHR data. We also discuss the relevance of these
results in the context of the empirical trade-off between fairness and model
performance
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