3,214 research outputs found
Outcomes Assessment and Health Care Reform
Argues for the use of outcomes assessment in measuring cost-effectiveness and quality to capture the overall impact of multi-dimensional treatment strategies and to identify healthcare systems that both adopt appropriate technologies and perform well
Capturing Trojans and Irregular Satellites - the key required to unlock planetary migration
It is now accepted that the Solar system's youth was a dynamic and chaotic
time. The giant planets migrated significant distances to reach their current
locations, and evidence of that migration's influence on the Solar system
abounds. That migration's pace, and the distance over which it occurred, is
still heavily debated. Some models feature systems in which the giant planets
were initially in an extremely compact configuration, in which Uranus and
Neptune are chaotically scattered into the outer Solar system. Others feature
architectures that were initially more relaxed, and smoother, more sedate
migration. To determine which of these scenarios best represents the formation
of our Solar system, we must turn to the structure of the system's small body
populations, in which the scars of that migration are still clearly visible.
We present the first results of a program investigating the effect of giant
planet migration on the reservoirs of small bodies that existed at that time.
As the planets migrate, they stir these reservoirs, scattering vast numbers of
small bodies onto dynamically unstable orbits in the outer Solar system. The
great majority of those bodies are rapidly removed from the system, through
collisions and ejections, but a small number become captured as planetary
Trojans or irregular satellites. Others are driven by the migration, leading to
a significant sculpting of the asteroid belt and trans-Neptunian region.
The capture and retention efficiencies to these stable reservoirs depend on
the particular migration scenario used. Advocates of chaotic migration from an
initially compact scenario argue that smoother, more sedate migration cannot
explain the observed populations of Trojans and irregular satellites. Our
results draw a strikingly different picture, revealing that such smooth
migration is perfectly capable of reproducing the observed populations.Comment: 13 pages, accepted for publication in the peer-reviewed proceedings
of the 12th annual Australian Space Science Conferenc
A problem structuring method for ecosystem-based management : the DPSIR modelling process
The purpose of this paper is to learn from Complex Adaptive Systems (CAS) theory to inform the development of Problem Structuring Methods (PSMs) both in general and in the specific context of marine management. The focus on marine management is important because it is concerned with a CAS (formed through the interconnection between natural systems, designed systems and social systems) which exemplifies their particularly ‘wicked' nature. Recognition of this compels us to take seriously the need to develop tools for knowledge elicitation and structuring which meet the demands of CAS. In marine management, chief among those tools is the DPSIR (Drivers - Pressures - State Changes - Impacts - Responses) model and, although widely applied, the extent to which it is appropriate for dealing with the demands of a CAS is questionable. Such questioning is particularly pertinent in the context of the marine environment where there is a need to not only recognise a broad range of stakeholders (a question of boundary critique) but also to manage competing knowledge (economic, local and scientific) and value claims. Hence this paper emphasises how a CAS perspective might add impetus to the development of a critical perspective on DPSIR and PSM theory and practice to promote a more systemic view of decision-making and policy development
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