On the possibility of plate tectonics on Venus

Several arguments have been put forward suggesting that Venus has no place tectonics. We examine some of these arguments and suggest that because conditions on the surface of Venus are very different from those on Earth, the arguments should be reconsidered. We show that in the absence of an ocean, the differential hypsographic curve of Earth would probably have only one mode, like that for Venus. We show that the atmosphere of Venus is quite capable of erosion, provided that near-surface velocities are about 1 m · sec −1 or more, and that therefore the “oceanic” areas on Venus, should they exist, are probably covered with some thickness of sediment. If sedimentation on Venus is at all rapid, it is likely that subduction zones could be filled up and made unrecognizable topographically. Because Venus does not have an ocean, and because its surface temperature is much greater than that on Earth, ridge crests on Venus have a much smaller topographic expression than those on Earth. If significant sedimentation occurs they would be completely unrecognizable topographically

A geomagnetic field reversal time scale back to 13.0 million years before present

The ages of reversals of the Earth's magnetic field have been dated accurately back to 3.4 m.y. ago. Between this time and the age of the Cretaceous-Tertiary boundary, dates for reversals have been calculated assuming a constant rate of sea-floor spreading in the South Atlantic Ocean. The presence of thick piles of lava flows in Iceland allows us to produce independent evidence for the ages of reversals back to 13.0 m.y. B.P. Because of the extreme regularity of extrusion of these lava flows, the measurement of their magnetic polarity allows us to correlate the lava flows which were extruded during the polarity intervals associated with sea-floor spreading anomalies. The measurement of many K-Ar ages on these lava flows also allows us to compare the ages of reversals assumed by the linear interpolation between the ages of 3.4 m.y. and the Cretaceous-Tertiary boundary at 66.5 m.y., with those suggested by the radiometric dates. We find that in general the assumption of constant spreading has been a good one, but suggest a small change in the ages of reversals, amounting to an increase of about 0.27 m.y. in ages of reversals between 8.5 and 13.0 m.y. ago

Magnetic and Petrologic Studies of Sediment Found Above Basalt in Experimental Mohole Core EM7

Office of Naval Research Contracts Nonr-477(10) and Nonr-477(37) Project NR-083-01

How are policy makers using evidence? Models of research utilisation and local NHS policy making

STUDY OBJECTIVE—This paper is based on a qualitative study that aimed to identify factors that facilitate or impede evidence-based policy making at a local level in the UK National Health Service (NHS). It considers how models of research utilisation drawn from the social sciences map onto empirical evidence from this study.
DESIGN—A literature review and case studies of social research projects that were initiated by NHS health authority managers or GP fundholders in one region of the NHS. In depth interviews and document analysis were used.
SETTING—One NHS region in England.
PARTICIPANTS—Policy makers, GPs and researchers working on each of the social research projects selected as case studies.
MAIN RESULTS—The direct influence of research evidence on decision making was tempered by factors such as financial constraints, shifting timescales and decision makers' own experiential knowledge. Research was more likely to impact on policy in indirect ways, including shaping policy debate and mediating dialogue between service providers and users.
CONCLUSIONS—The study highlights the role of sustained dialogue between researchers and the users of research in improving the utilisation of research-based evidence in the policy process.


Keywords: evidence-based policy making; research/policy interface; research utilisatio