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At least 883 records · Page 49Linked to original sources
PubMed1992

Cardiac pacing and aviation.

Certain applicants with stable disturbances of rhythm or conduction requiring cardiac pacing, in whom no other disqualifying condition is present, may be considered fit for medical certification restricted to multi-crew operations. The reliability of modern pacing systems appears adequate to permit restricted certification even in pacemaker dependent subjects except for certain models of pacemakers and leads known to be at increased risk of failure. These are to be avoided. There is little evidence to suggest that newer devices are any more reliable than their predecessors. Single and dual chamber systems appear to have similar reliability up to 4 years, after which time significant attrition of dual chamber devices occurs, principally due to battery depletion. All devices require increased scrutiny as they approach their end of life as predicted from longevity data and pacing characteristics. Unipolar and bipolar leads are of similar reliability, apart from a number of specific bipolar polyurethane leads which have been identified. Atrial leads, particularly those without active fixation, are less secure than ventricular leads and applicants who are dependent on atrial sensing or pacing should be denied certification. Bipolar leads are to be preferred due to the lower risk of myopotential and exogenous EMI. Sensor-driven adaptive-rate pacing systems using active sensors may have reduced longevity and require close scrutiny. Activity-sensing devices using piezoelectric crystal sensors may be subject to significant rate rises in rotary wing aircraft. The impracticality of restricted certification in helicopters will, in any event, preclude certification. Such devices would best be avoided in hovercraft (air cushioned vehicle) pilots. Only minor rate rises are likely in fixed-wing aircraft which are unlikely to be of significance. Anti-tachycardia devices and implanted defibrillators are inconsistent with any form of certification to fly.

Aerospace Medicine↗
PubMed2002

Study of the dosimetric characteristics of cosmic radiation at civil aviation altitudes.

The dependence of the doses on solar activity for intermediate levels of the solar modulation parameter has been studied by means of simulations carried out by the Monte Carlo transport code FLUKA. The vertical cut-off rigidities investigated lie between 0.4 and 6.1 GV. The calculated results show that the linear dependence proposed in a previous work, for the effective dose rate as a function of the solar modulation parameter, can be considered as an acceptable approximation. In addition, some dosimetric characteristics of cosmic radiation and some properties of the dosemeters in use for monitoring in the cosmic ray environment have been analysed with a view to simplifying measurements. The depth-dose curves in the ICRU sphere and the response of a tissue-equivalent ionisation chamber have been determined by the FLUKA code for a number of cosmic ray spectra On the basis of the calculated results, it is concluded that a value of the depth. d, which would make the ambient dose equivalent a conservative predictor of the effective dose, cannot be specified for cosmic radiation. However, the operational quantity can be useful in order to verify the predictions of Monte Carlo calculations. It is demonstrated that a crude approximation of the ambient dose equivalent could be obtained by multiplying by 2 the absorbed dose measured by a tissue-equivalent ionisation chamber with wall thickness of 10 mm.

Aircraft↗
PubMed1990

Health physics concerns in commercial aviation.

Airline pilots and flight attendants are occupationally exposed to cosmic radiation. There has been uncertainty about how to handle the radiation protection requirements of their unique situation. Calculated dose equivalents associated with typical flight routes and crewmember work patterns have recently been published. The results show that flight attendants and pilots on ordinary subsonic aircraft can receive annual doses approaching 10 mSv y-1. I argue that flight crewmembers should receive specific education regarding the risks to their health from radiation exposure. I also argue that a suitable dosimeter system should be employed to provide crewmembers with information on their total doses. This is of particular importance for pregnant crewmembers who risk exceeding recommended fetal dose limits by working some routes during their pregnancy. In addition to airline crewmembers, business "frequent flyers" may receive significant occupational exposures while traveling. They too need appropriate education in order to assist them in assessing their risks from such exposures. Finally, flying during a large solar proton event would significantly increase the dose that would be received. During such an event, the total dose to the fetus of a pregnant crewmember or passenger might exceed the 0.5 mSv recommended monthly maximum. Warnings and action plans for these special circumstances should be improved.

Aviation↗
PubMed2006

Radiation protection at an aviation museum.

The U.S. Nuclear Regulatory Commission (U.S. NRC) will soon publish a proposed amendment to its rules that will classify the naturally occurring isotope Ra as "byproduct material" subject to its regulatory control. One of the uses of radium in the first half of the twentieth century was as a source of energy that would make certain consumer products "glow in the dark." In addition to wristwatches and other timepieces, this form of self-luminescence was widely used on aircraft instruments. There have been a number of facilities where large numbers of such instruments were stored and leakage of this isotope occurred. Subsequent decontamination of these areas, including expensive disposal of the radioactive waste, was required. We were asked to evaluate the potential hazards of aircraft and aircraft instruments at a museum in New York City, specifically the decommissioned aircraft carrier USS Intrepid. We present the results of our investigation and discuss the implications as they relate to the proposed new U.S. NRC regulations and compatibility issues with State regulations.

Aviation↗
PubMed2004

A knowledge-based framework for image enhancement in aviation security.

The main aim of this paper is to present a knowledge-based framework for automatically selecting the best image enhancement algorithm from several available on a per image basis in the context of X-ray images of airport luggage. The approach detailed involves a system that learns to map image features that represent its viewability to one or more chosen enhancement algorithms. Viewability measures have been developed to provide an automatic check on the quality of the enhanced image, i.e., is it really enhanced? The choice is based on ground-truth information generated by human X-ray screening experts. Such a system, for a new image, predicts the best-suited enhancement algorithm. Our research details the various characteristics of the knowledge-based system and shows extensive results on real images.

Algorithms↗
PubMed2000

Error, stress, and teamwork in medicine and aviation: cross sectional surveys.

OBJECTIVES: To survey operating theatre and intensive care unit staff about attitudes concerning error, stress, and teamwork and to compare these attitudes with those of airline cockpit crew. DESIGN: : Cross sectional surveys. SETTING: : Urban teaching and non-teaching hospitals in the United States, Israel, Germany, Switzerland, and Italy. Major airlines around the world. PARTICIPANTS: : 1033 doctors, nurses, fellows, and residents working in operating theatres and intensive care units and over 30 000 cockpit crew members (captains, first officers, and second officers). MAIN OUTCOME MEASURES: : Perceptions of error, stress, and teamwork. RESULTS: : Pilots were least likely to deny the effects of fatigue on performance (26% v 70% of consultant surgeons and 47% of consultant anaesthetists). Most pilots (97%) and intensive care staff (94%) rejected steep hierarchies (in which senior team members are not open to input from junior members), but only 55% of consultant surgeons rejected such hierarchies. High levels of teamwork with consultant surgeons were reported by 73% of surgical residents, 64% of consultant surgeons, 39% of anaesthesia consultants, 28% of surgical nurses, 25% of anaesthetic nurses, and 10% of anaesthetic residents. Only a third of staff reported that errors are handled appropriately at their hospital. A third of intensive care staff did not acknowledge that they make errors. Over half of intensive care staff reported that they find it difficult to discuss mistakes. CONCLUSIONS: Medical staff reported that error is important but difficult to discuss and not handled well in their hospital. Barriers to discussing error are more important since medical staff seem to deny the effect of stress and fatigue on performance. Further problems include differing perceptions of teamwork among team members and reluctance of senior theatre staff to accept input from junior members.

Attitude↗