RESUMEN
The lack of reach performance data obtained under space-flight conditions has led to questions regarding the operational impact of higher G loads on crew performance. This investigation studied the effect of increasing G loads on reach capability. Ten subjects were exposed in a stepwise fashion to increasing accelerations resulting in G loads of from +1 to +6 Gx in the Brooks AFB centrifuge. Four subjects wore the pre-Challenger Launch Entry Helmet (LEH) ensemble and six the current Launch Entry Suit (LES). The subjects performed standardized reach sweeps at each G level. These sweeps were recorded on videotape and subsequently analyzed using a 3-dimensional motion analysis system. Significant differences in forward and overhead reach were determined using the General Linear Models (GLM) procedure of the Statistical Analysis System (SAS) program. The results from this study suggest that purposeful movement can be realistically performed in the LEH at the 5 G level and in the LES up to the 4 G level.
Asunto(s)
Gravitación , Trajes Gravitatorios/normas , Movimiento/fisiología , Humanos , Distribución Aleatoria , Vuelo Espacial , Análisis y Desempeño de TareasRESUMEN
The Challenger accident prompted the creation of a crew escape system which replaced the former Launch Entry Helmet (LEH) ensemble with the current Launch Entry Suit (LES). However, questions were raised regarding the impact of this change on crew reach capability. Our study addressed the question of reach capability and its effect on realistic ground-based training for Space Shuttle missions. Eleven subjects performed reach sweeps in both the LEH and LES suits during 1 and 3 Gx acceleration trials in the Brooks AFB, TX, centrifuge. These reach sweeps were recorded on videotape and subsequently analyzed using a three-dimensional motion analysis system. The ANOVA procedure of the Statistical Analysis System (SAS) program was used to evaluate differences in forward and overhead reach. The results showed that the LES provided less reach capability than its predecessor, the LEH. This study also demonstrated that, since there was no substantial difference between 1 and 3 Gx reach sweeps in the LES, realistic Shuttle launch training may be accomplished in ground-based simulators.
Asunto(s)
Aceleración/efectos adversos , Trajes Gravitatorios , Vuelo Espacial , Adulto , Humanos , Masculino , Persona de Mediana EdadRESUMEN
We have developed a water-sealed infant calorimeter (IC) system which uses the techniques of closed-circuit spirometry to measure oxygen consumption (VO2) in premature and full-term infants. Carbon dioxide production (VCO2) is simultaneously calculated from the effluent mixed expired CO2 and the circulating flowrate. Respiratory Quotient (RQ) and Energy Expenditure (EE) are then calculated from the primary data. Measurement of VO2, VCO2, and calculation of RQ were +/- 5.0% of predicted values determined by burning ethyl alcohol or volume extraction and CO2 infusion in our bench model. Measurement in 11 premature infants produced mean values for VO2 and VCO2 of 8.5 +/- 2.5 ml/min/kg and 8.5 +/- 2.4 ml/min/kg, respectively. This system is noninvasive, does not interfere with infant tube feedings or iv infusions, and permits safe, long-term monitoring of the infant's metabolic activity. It allows a more exact matching or oral or intravenous feedings to the actual energy expenditure of the infants, and offers potential advantages for the nutritional management of sick infants.