RESUMEN
The interest of manufacturing, governmental, and safety personnel in using paint schemes on propeller and rotor blades is based on improving the visual conspicuity of those blades when they are rotating. While propeller and rotor paint schemes may serve to reduce the number of fatalities and injuries due to contact with a rotating blade, there is little information about the circumstances surrounding such accidents. Brief reports provided by the National Transportation Safety Board of all "propeller-to-person" accidents from 1965-79 were examined and analyzed in terms of airport lighting conditions, actions of pilots, actions of passengers and groundcrew, phase of flight operations, weather conditions, and others. Analyses based on 319 accidents showed a marked drop in the frequency of "propeller-to-person" accidents from 1975 through 1978. Several types of educational efforts directed toward pilots and groundcrew, both prior to and during that 4-year period, were examined as possible factors contributing to the accident rate decline. Accident patterns provide a basis for assessing the probable efficacy of various recommendations, including propeller conspicuity, for further reducing "propeller-to-person" accidents.
Asunto(s)
Accidentes de Aviación , Prevención de Accidentes , Humanos , Estados UnidosRESUMEN
Spatial disorientation (SD) was the third highest "cause" of fatal accidents in small, fixed-wing aircraft and closely related to the second highest "cause"--"continued VFR flight into adverse weather." SD was a cause or factor in 16% of all fatal accidents. When SD was ascribed as a cause or factor in an accident, 90% of the time that accident involved fatalities. Small, fixed-wing aircraft under 12,500 lb (570 kg) accounted for 97.3% of all SD accidents. Inclement weather was associated with 42% of all fatal accidents, and SD was a cause or factor in 35.6% of these. Flight was initiated into and continued into adverse weather in 19.7 and 68.7%, respectively, of SD weather-related fatal accidents. Fog (56.8%) and rain (41.8%) were the most prevalent adverse weather conditions. These and other data attest to the importance of this psychophysiological phenomenon in flight safety.
Asunto(s)
Accidentes de Aviación , Orientación , Percepción Espacial , Adulto , Medicina Aeroespacial , Aeronaves , Humanos , Masculino , Tiempo (Meteorología)RESUMEN
Heat-induced hyperthermia can be a major problem in dogs shipped during summer months. Dogs shipped by air transport can encounter temperatures as high as 54.4 C. Usually, little concern is given to effects produced by hyperthermia. To assess the heat stress problem, 20 dogs were exposed to a temperature of 54.4 C for 30 minutes--10 dogs at 15% relative humidity and 10 dogs at 35%. Dogs did not die as a result of exposure, but certain transient and permanent changes occurred. All dogs had increased heart rate, rectal temperature, blood pH, hemoglobin concentration, packed cell volume, and erythrocyte count. Body weight and PVCO2, decreased. Differences also were shown between the 2 humidity group for blood PH PVCO2, rectal temperature, and weight loss. The major tissue changes attributed to hyperthermia were fragmentation of the myocardium, acute cortical necrosis in kidney, and marked degenerative changes in the cerebellum and cerebral cortex. Changes in the cerebellum and cerebral cortex were considered severe and permanent.
Asunto(s)
Aeronaves , Enfermedades de los Perros , Fiebre/veterinaria , Estrés Fisiológico/veterinaria , Transportes , Animales , Temperatura Corporal , Peso Corporal , Cerebelo/patología , Corteza Cerebral/patología , Enfermedades de los Perros/patología , Perros , Exposición a Riesgos Ambientales , Fiebre/patología , Riñón/patología , Pulmón/patología , Masculino , Recto/fisiopatología , Estrés Fisiológico/patologíaRESUMEN
A series of cases is reported in which pink teeth were observed during the postmortem period. Most cases were associated with decomposition in a moist environment. Experimental procedures led to the extraction of pink material from dentin and demonstration that hemoglobin and serum proteins were present. The pink-tooth phenomenon was duplicated in human teeth by instilling into the pulp chambers whole blood and blood with the red cells hemolyzed. The change was manifested in teeth of dogs after freezing, heating, and decomposition in a moist environment. The authors postulate that pink teeth occur as a result of breakdown of red blood cells in the pulp chamber of the tooth and diffusion of hemoglobin and other serum proteins into the dentin via the dential tubules. Histochemical studies show that the brown or gray material in some teeth subjected to postmortem aging is probably hemoglobin and serum proteins. Factors of age, vascularity of the pulp chamber, and postmortem conditions are discussed in relation to the postmortem development of pink teeth.