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PubMed1994

Convection driven zonal flows and vortices in the major planets.

The dynamical properties of convection in rotating cylindrical annuli and spherical shells are reviewed. Simple theoretical models and experimental simulations of planetary convection through the use of the centrifugal force in the laboratory are emphasized. The model of columnar convection in a cylindrical annulus not only serves as a guide to the dynamical properties of convection in rotating sphere; it also is of interest as a basic physical system that exhibits several dynamical properties in their most simple form. The generation of zonal mean flows is discussed in some detail and examples of recent numerical computations are presented. The exploration of the parameter space for the annulus model is not yet complete and the theoretical exploration of convection in rotating spheres is still in the beginning phase. Quantitative comparisons with the observations of the dynamics of planetary atmospheres will have to await the consideration in the models of the effects of magnetic fields and the deviations from the Boussinesq approximation.

Journal Article↗
PubMed2006

Powering the planet: chemical challenges in solar energy utilization.

Global energy consumption is projected to increase, even in the face of substantial declines in energy intensity, at least 2-fold by midcentury relative to the present because of population and economic growth. This demand could be met, in principle, from fossil energy resources, particularly coal. However, the cumulative nature of CO(2) emissions in the atmosphere demands that holding atmospheric CO(2) levels to even twice their preanthropogenic values by midcentury will require invention, development, and deployment of schemes for carbon-neutral energy production on a scale commensurate with, or larger than, the entire present-day energy supply from all sources combined. Among renewable energy resources, solar energy is by far the largest exploitable resource, providing more energy in 1 hour to the earth than all of the energy consumed by humans in an entire year. In view of the intermittency of insolation, if solar energy is to be a major primary energy source, it must be stored and dispatched on demand to the end user. An especially attractive approach is to store solar-converted energy in the form of chemical bonds, i.e., in a photosynthetic process at a year-round average efficiency significantly higher than current plants or algae, to reduce land-area requirements. Scientific challenges involved with this process include schemes to capture and convert solar energy and then store the energy in the form of chemical bonds, producing oxygen from water and a reduced fuel such as hydrogen, methane, methanol, or other hydrocarbon species.

Carbon↗
PubMed2000

Brown dwarfs: at last filling the gap between stars and planets.

Until the mid-1990s a person could not point to any celestial object and say with assurance that "here is a brown dwarf." Now dozens are known, and the study of brown dwarfs has come of age, touching upon major issues in astrophysics, including the nature of dark matter, the properties of substellar objects, and the origin of binary stars and planetary systems.

Journal Article↗
PubMed2004

Alignment of the policy planets: behind the implementation of the Northern Territory (Australia) Living With Alcohol programme.

The Northern Territory Living With Alcohol Programme (LWAP), implemented in Australia from 1991 to 2000, has been hailed as a successful example of a comprehensive public health alcohol policy, especially in its first 4 years--1991/92 to 1995/96. This paper draws upon a policy analysis of the LWAP currently in progress to identify and describe the factors that made implementation possible at this time. I argue that programme implementation was shaped by a remarkable alignment of agencies and actors in the political, fiscal, administrative and industrial domains. This alignment of forces, however, owed as much to contingency as to planning and did not endure. Although the policy itself remained unchanged and continued to generate significant achievements, the alignment of forces sustaining it began to fragment from late 1995 onwards. The paper concludes by exploring the implications of the analysis for alcohol policy in other domains, and for the relationship between evidence regarding effectiveness and other components of the policy process.

Alcoholism↗