A Bayesian analysis of extrasolar planet data for HD 208487

Precision radial velocity data for HD 208487 has been re-analyzed using a new Bayesian multi-planet Kepler periodogram. The periodgram employs a parallel tempering Markov chain Monte Carlo algorithm with a novel statistical control system. We confirm the previously reported orbit (Tinney et al. 2005) of 130 days. In addition, we conclude there is strong evidence for a second planet with a period of 998 -62 +57 days, an eccentricity of 0.19 -0.18 +0.05, and an M sin i = 0.46 -0.13 +0.05 of Jupiter's mass.Comment: For publication in ``Bayesian Inference and Maximum Entropy Methods'', San Jose 2005, K. H. Knuth, A. E. Abbas, R. D. Morris, J. P. Castle (eds.), AIP Conference Proceedin

A Bayesian periodogram finds evidence for three planets in HD 11964

A Bayesian multi-planet Kepler periodogram has been developed for the analysis of precision radial velocity data (Gregory 2005b and 2007). The periodogram employs a parallel tempering Markov chain Monte Carlo algorithm. The HD 11964 data (Butler et al. 2006) has been re-analyzed using 1, 2, 3 and 4 planet models. Assuming that all the models are equally probable a priori, the three planet model is found to be >= 600 times more probable than the next most probable model which is a two planet model. The most probable model exhibits three periods of 38.02+0.06-0.05, 360+-4 and 1924+44-43 d, and eccentricities of 0.22+0.11-0.22, 0.63+0.34-0.17 and 0.05+0.03-0.05, respectively. Assuming the three signals (each one consistent with a Keplerian orbit) are caused by planets, the corresponding limits on planetary mass (M sin i) and semi-major axis are 0.090+0.15-0.14 M_J, 0.253+-0.009 au, 0.21+0.06-0.07 M_J, 1.13+-0.04 au, 0.77+-0.08 M_J, 3.46+-0.13 au, respectively. The small difference (1.3 sigma) between the 360 day period and one year suggests that it might be worth investigating the barycentric correction for the HD 11964 data

Soft-pulse dynamical decoupling in a cavity

Dynamical decoupling is a coherent control technique where the intrinsic and extrinsic couplings of a quantum system are effectively averaged out by application of specially designed driving fields (refocusing pulse sequences). This entails pumping energy into the system, which can be especially dangerous when it has sharp spectral features like a cavity mode close to resonance. In this work we show that such an effect can be avoided with properly constructed refocusing sequences. To this end we construct the average Hamiltonian expansion for the system evolution operator associated with a single ``soft'' pi-pulse. To second order in the pulse duration, we characterize a symmetric pulse shape by three parameters, two of which can be turned to zero by shaping. We express the effective Hamiltonians for several pulse sequences in terms of these parameters, and use the results to analyze the structure of error operators for controlled Jaynes-Cummings Hamiltonian. When errors are cancelled to second order, numerical simulations show excellent qubit fidelity with strongly-suppressed oscillator heating.Comment: 9pages, 5eps figure

The production of glow precursors by oxidative erosion of spacecraft surfaces

Erosion rates of organic materials are measured during a recent flight of the shuttle (STS-8). Several forms of carbon and a variety of thermosetting and thermoplastic polymers are exposed to the ram beam of atomic oxygen. Arrhenius energies of about 1000 to 2000 cal/mole were measured from the rate dependencies on temperature. If some simple assumptions are made about the chemical nature of the desorbed species, the data can be used to estimate production rates at surfaces in orbit under different conditions of temperature, oxygen atom flux, and material surface conditions

Survey of hydrogen production and utilization methods. Volume 1: Executive summary

The use of hydrogen as a synthetic fuel is considered. Processes for the production of hydrogen are described along with the present and future industrial uses of hydrogen as a fuel and as a chemical feedstock. Novel and unconventional hydrogen-production techniques are evaluated, with emphasis placed on thermochemical and electrolytic processes. Potential uses for hydrogen as a fuel in industrial and residential applications are identified and reviewed in the context of anticipated U.S. energy supplies and demands. A detailed plan for the period from 1975 to 1980 prepared for research on and development of hydrogen as an energy carrier is included