Using simulation to estimate the power of a badger vaccine trial

The aim of this study was to estimate the power of a badger vaccine field trial using simulation techniques. The effects of sample size, sensitivity and specificity of the diagnostic test, transmission rate between unvaccinated badgers, Vaccine Efficacy for Susceptibility (VES) and Vaccine Efficacy for Infectiousness (VEI) on study power were determined. The most striking result was the large effect of the specificity of the diagnostic test on study power. Sample size had a small effect on power. Study power increased with increasing transmission rate between non-vaccinated badgers. Changes in VES had a higher impact on power than changes in VEI. In summary, study power in group randomized trials depends not only on sample size but on many other parameters. In the current vaccine trial, power was highly dependent on the specificity of the diagnostic test. Therefore, it is critical that the diagnostic test used in the badger vaccine trial is optimized to maximise test specificity

High-energy emission from NGC 5506, the brightest hard X-ray Narrow Line Seyfert 1 galaxy

We present results on the hard X-ray emission of NGC 5506, the brightest narrow line Seyfert 1 galaxy above 20 keV. All the recent observations by INTEGRAL, Swift and Suzaku have been analysed and spectral analysis during nine separated time periods has been performed. While flux variations by a factor of 2 were detected during the last 7 years, only moderate spectral variations have been observed, with the hint of a hardening of the X-ray spectrum and a decrease of the intrinsic absorption with time. Using Suzaku observations it is possible to constrain the amount of Compton reflection to R = 0.6-1.0, in agreement with previous results on the source. The signature of Comptonisation processes can also be found in the detection of a high-energy cut-off during part of the observations, at Ec = 40-100 keV. When a Comptonisation model is applied to the Suzaku data, the temperature and the optical depth of the Comptonising electron plasma are measured at kT = 60-80 keV and tau = 0.6-1.0, respectively. The properties inferred for NGC 5506 in this study agree with those based on other data sets for the same AGN, and fit the picture of NLS1 having in general lower high-energy cut-offs at hard X-rays than their broad line equivalent.Comment: 8 pages, 3 figures, 1 table. Proceedings of the Workshop "Narrow-Line Seyfert 1 Galaxies and Their Place in the Universe", Milano, April 4-6, 2011 (Proceedings of Science, http://pos.sissa.it/cgi-bin/reader/conf.cgi?confid=126

Covers of surfaces with fixed branch locus.

Number theory, Algebra and Geometr