BOOK REVIEW: A Review of God and Contemporary Science, by Philip Clayton

This is a book review of God and Contemporary Science by Philip Clayton

An Integrated Analysis of Radial Velocities in Planet Searches

We discuss a Bayesian approach to the analysis of radial velocities in planet searches. We use a combination of exact and approximate analytic and numerical techniques to efficiently evaluate chi-squared for multiple values of orbital parameters, and to carry out the marginalization integrals for a single planet including the possibility of a long term trend. The result is a robust algorithm that is rapid enough for use in real time analysis that outputs constraints on orbital parameters and false alarm probabilities for the planet and long term trend. The constraints on parameters and odds ratio that we derive compare well with previous calculations based on Markov Chain Monte Carlo methods, and we compare our results with other techniques for estimating false alarm probabilities and errors in derived orbital parameters. False alarm probabilities from the Bayesian analysis are systematically higher than frequentist false alarm probabilities, due to the different accounting of the number of trials. We show that upper limits on the velocity amplitude derived for circular orbits are a good estimate of the upper limit on the amplitude of eccentric orbits for eccentricities less than about 0.5.Comment: 16 pages, 9 figures, to appear in MNRA

Quantum measurement and decoherence

Distribution functions defined in accord with the quantum theory of measurement are combined with results obtained from the quantum Langevin equation to discuss decoherence in quantum Brownian motion. Closed form expressions for wave packet spreading and the attenuation of coherence of a pair of wave packets are obtained. The results are exact within the context of linear passive dissipation. It is shown that, contrary to widely accepted current belief, decoherence can occur at high temperature in the absence of dissipation. Expressions for the decoherence time with and without dissipation are obtained that differ from those appearing in earlier discussions

High-efficiency AlGaAs-GaAs Cassegrainian concentrator cells

AlGaAs-GaAs heteroface space concentrator solar cells have been fabricated by metalorganic chemical vapor deposition. AMO efficiencies as high as 21.1% have been observed both for p-n and np structures under concentration (90 to 100X) at 25 C. Both cell structures are characterized by high quantum efficiencies and their performances are close to those predicted by a realistic computer model. In agreement with the computer model, the n-p cell exhibits a higher short-circuit current density

Correlation Times and Complex Polarisability for Linear and Spherical Top Molecules

We describe a simple method for calculating correlation times and complex polarisabilities from the orientational autocorrelation functions of molecules executing rotational Brownian motion. The expression for the autocorrelation function is first rearranged to display explicitly its asymptotic form for large times. We apply the method to recent results on the autocorrelation functions for linear and spherical-top molecules

Most Americans are now opposed to laws against interracial marriage, but their behavior does not yet reflect these attitudes

Recent decades have seen a dramatic fall in the number of people that support laws which prohibit interracial marriages, and an increase in the number of these marriages. But why does the rate of interracial marriages remain so low, when compared to same-race marriages? Using national data from the past three decades, Ginny E. Garcia, Richard Lewis Jr., and Joanne Ford-Robertson show that while attitudes towards interracial marriages have changed, many groups still have negative attitudes towards Black-White unions. They find that those who perceive social and economic competition with Blacks, such as those with lower levels of education, were more likely to support laws that prohibit interracial marriages and engage in behaviors that prevent Black’s wider participation in society

The Quantum Langevin Equation

The macroscopic description of a quantum particle with passive dissipation and moving in an arbitrary external potential is formulated in terms of the generalized Langevin equation. The coupling with the heat bath corresponds to two terms: a mean force characterized by a memory function μ(t) and an operator-valued random force. Explicit expressions are given for the correlation of the random force. The random force is never Markovian. It is shown that μ̃(z), the Fourier transform of the memory function, is a positive real function, analytic in the upper half plane and with Re{μ̃(ω + i0^+)} a positive distribution on the real axis. This form is then derived for the independent-oscillator (IO) model of a heat bath. It is shown that the most general quantum Langevin equation can be realized by this simple model. A critical comparison is made with a number of other models which have appeared in the literature