2,530 research outputs found
Anaesthetic explosions
The flammability and explosibility of many of the more useful anaesthetic agents are properties regarded with apprehension by a large number of anaesthetists and surgeons. Indeed, because of these properties, such an excellent anaesthetic agent as di-ethyl ether may become surrounded by as many taboos as the wooden image worshipped by a savage African tribe. The drama of fire and explosion in the operating theatre is greater than that surrounding an atomic explosion, but the reason for this is that atomic explosions are more frequent and so less wondered at
Winter residency and site association in the critically endangered North East Atlantic spurdog (Squalus acanthias)
Identification and incorporation of residential behaviour into elasmobranch management plans has the potential to substantially increase their effectiveness by identifying sites where Marine Protected Areas (MPAs) might be used to help conserve species with high migratory potential. There is evidence that spurdog (Squalus acanthias) displays site association in some parts of its global distribution, but this has currently not been shown within the North East Atlantic where it is critically endangered. Here we investigate the movements of electronically tagged spurdog within Loch Etive, a sea loch on the west coast of Scotland. Archival data storage tags (DSTs), that recorded depth and temperature, revealed that mature female spurdog over wintered within the loch, restricting their movements to the upper basin, and remaining either in the loch or the local vicinity for the rest of the year. This finding was supported by evidence for limited movements from conventional mark/recapture data and acoustically tagged individual spurdog. Some of the movements between the loch basins appear to be associated with breeding and parturition events. This high level of site association suggests that spatial protection of the loch would aid the conservation of different age and sex classes of spurdog
Fail-Safe vs. Safe-Fail Catastrophes
This paper is meant to serve two purposes. First, to extend the usefulness of catastrophe theory as a tool to aid our perception of a partially known world. This theory is a newly emerged branch of topology and, as such, begins to fill a large void in our arsenal of qualitative analytical tools. It is not appropriate for all important and interesting situations, particularly those requiring precise numerical results. But it is hoped that it can provide an important missing element for our environmental management tool kit.
The second purpose is to report upon some deliberations precipitated by a recent paper of Beer and Casti (1975). We shall follow, to some degree, their development. We shall also borrow some of their examples and terminology in order to emphasize some fundamentally different strategies for managing unexpected events
Towards a Structural View of Resilience
The result of resilience is persistence: the maintenance
of certain characteristic behavioral properties in the face
of stress, strain and surprise. But the origins of this resilient
behavior lie in the structure of the systems which
concern us. Our need as policy analysts may only be one of
comparative measures: Which system is more resilient? But
as active designers -- as engineers, managers, or responsible
policy advisors -- we need to be able to say what mechanisms
or relationships make a system resilient, and what actions we
can take to make it more or less so.
This need for a causal view of resilience led us to a
search for persistence-promoting (or "resilient") mechanisms
and relationships in a variety of natural and man-made systems
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