E Saether | PubMed Health

PubMed2005

Dynamic instability in intergranular fracture.

A molecular-dynamics model for crack propagation under steady-state conditions is used to study dynamic instabilities along a grain boundary in aluminum that occur when the crack speed approaches 1/3 of the material's Rayleigh wave speed. Instead of crack branching, as is characteristic for a crack propagating in a homogeneous environment, the instability of an intergranular crack results in a periodic series of dislocation bursts. These bursts limit the crack speed and produce velocity oscillations with a large increase in energy dissipation that increases the grain boundary toughness.

Journal Article↗

PubMed1992

[Emergency services in Norway. A questionnaire study].

A questionnaire survey of primary health care emergency services in Norway (1991) covered 71 municipalities organized into 43 regions containing about 15% of the Norwegian population. The large cities are excluded. Long distances to travel and frequent duty periods cause some problems, but not for the majority of the population or doctors who participated in the survey. In several regions, a significant part of the service is covered by locums. Written directives for the services are rare. The availability of the doctor on duty falls short several places, owing to lack of satisfactory routines and the occasional need to accompany a patient to hospital. In more than half the regions communication systems are unsatisfactory and will have to be upgraded. In almost half the regions emergency telephone calls are sometimes answered by staff without a medical background. A code of practice or central regulation are suggested as possible ways of improving the services.

Emergency Medical Services↗