Richard K. Barrett

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The effects of raising cockroaches, Leucophaea maderae, in non-24-h light cycles on the response of the circadian system to light was examined. 1. Phase response curves (PRC) were measured for 6-h light pulses for animals raised in LD 11:11 (T22), LD 12:12 (T24), and LD 13:13 (T26). The delay portion of the PRC was found to be significantly reduced in T22(More)
1. The effects of raising cockroaches, Leucophaea maderae, in non-24 h light cycles on circadian rhythms in adults were examined. The average period (tau) of freerunning rhythms of locomotor activity of animals exposed to LD 11:11 (T22) during post-embryonic development was significantly shorter (tau = 22.8 +/- 0.47 SD, n = 85) than that of animals raised(More)
1. The effects of raising cockroaches,Leucophaea maderae, in non-24 h light cycles on circadian rhythms in adults were examined. The average period (Τ) of freerunning rhythms of locomotor activity of animals exposed to LD 11∶11 (T22) during post-embryonic development was significantly shorter (Τ=22.8±0.47 SD,n=85) than that of animals raised in LD 12∶12(More)
A two-dimensional particle code that simulates electrical breakdown of gases by modeling avalanche evolution from the initial ion-electron pair up to the development of a streamer is presented. Trajectories of individual particles are followed, the self-field is included consistently and collision processes are accurately modeled using experimentally(More)
We demonstrate that the high isotropy of the Cosmic Microwave Background (CMB), combined with the Copernican principle, is not sufficient to prove homogeneity of the universe – in contrast to previous results on this subject. The crucial additional factor not included in earlier work is the acceleration of the fundamental observers. We find the complete(More)
We discuss inhomogeneous cosmological models which satisfy the Copernican principle. We construct some inhomogeneous cosmological models starting from the ansatz that the all the observers in the models view an isotropic cosmic microwave background. We discuss multi-fluid models, and illustrate how more general inhomogeneous models may be derived, both in(More)
We demonstrate that the high isotropy of the Cosmic Microwave Background (CMB), combined with the Copernican principle, is not sufficient to prove homogeneity of the universe – in contrast to previous results on this subject. The crucial additional factor not included in earlier work is the acceleration of the fundamental observers. We find the complete(More)
The Discrete Absorption Components (DACs) commonly observed in the ultraviolet lines of hot stars have previously been modelled by dynamical simulations of Corotating Interaction Regions (CIRs) in their linedriven stellar winds. Here we apply the kinematic DAC inversion method of Brown et al. to the hydrodynamical CIR models and test the reliability of the(More)
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