A breif overview of network centric warfare.
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Forecasting↗
Biomedical subjects
E M Forster
Publications and source records attributed to E M Forster.
Smart Aircrew Integrated Life Support System.
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Aerospace Medicine↗
The role of anaerobic power in human tolerance to simulated aerial combat maneuvers.
The relationships of anaerobic power, blood lactate levels, and selected anthropometric measurements to +Gz tolerance were examined in 10 adult males. Upper and lower body anaerobic indices were determined by Wingate anaerobic tests (WT). Acceleration tolerance was measured as duration time for a simulated aerial combat maneuver (SACM) centrifuge profile with alternating 4.5 and 7 +Gz 15-s plateaus until exhaustion. Group mean (+/- SD) for SACM duration was 250 +/- 97 s. Peak blood lactate concentration was 4.9 +/- 1.5 mmol/L and overall rating of perceived exertion was 7.4 +/- 2.1 using the Borg Category-Ratio Scale. Group mean for WT lower body 30-s mean power (MP, index of anaerobic performance) was 620 +/- 128 W; peak power (PP, highest 5-s power output) was 851 +/- 169 W. Upper body MP and PP were 380 +/- 68 W and 497 +/- 81 W, respectively. SACM duration time was positively correlated (p < 0.05) with lower body MP and PP, upper body PP, various body circumferences, weight, fat-free body weight, and height; but did not correlate with WT power outputs relative to body weight, or with other SACM variables. Results suggest that anaerobic power is an important physiologic component in SACM tolerance.
Acceleration↗
Heart rate response of aircrew during recovery from gradual onset rate +Gz exposures.
A quantitative study of cardiac recovery from +Gz was accomplished to define recovery heart rate (HR) of aircrew exposed to the acceleration environment in the centrifuge. Electrocardiographic data from 30 pilots were analyzed. The profiles considered were gradual onset rate exposure of 0.1 G/s. Continuous R-R interval measurements were recorded prior to +Gz and immediately after peak +Gz was attained. In 57% of the subjects, HR decreased 57 +/- 18 bpm an average of 11 +/- 4 s after maximum HR was attained. This rate was maintained for 17 +/- 5 s. The remaining 43% of the subjects exhibited a gradual decline in HR until reaching a steady state 60 s after the exposure. Heart rate was also observed to oscillate 42 +/- 15 bpm about the mean values before achieving a steady state during both types of recovery. The oscillatory HR did not have fixed upper and lower limits. Description of the recovery HR during +Gz exposures establishes a baseline for comparison with atypical responses and a basis for describing cardiovascular response to alternate and more complex +Gz profiles.
Acceleration↗
Effect of pyridostigmine bromide on acceleration tolerance and performance.
Pyridostigmine Bromide (PB) is used as a pre-exposure antidote for the prevention of potentially lethal effects of certain chemical warfare nerve agents by reversibly inhibiting acetylcholinesterase (AChE). This study was designed to determine whether PB has any deleterious effects on acceleration tolerance (+Gz) or performance. Double-blind placebo trials were conducted to evaluate the effects of PB (90 mg) per day on +Gz tolerances and performance. Three types of exposures were used: 1) gradual onset rate (GOR) exposures of 0.1 G/s; 2) a series of rapid onset rate (ROR) exposures of 6.0 G/s; and 3) a simulated aerial combat maneuver (SACM) of 4.5 to 9.0 +Gz. Performance tasks included the Unified Tri-Service Cognitive Performance Assessment Battery (UTC-PAB). The subjects were not able to correlate their symptoms with PB, placebo, or the acceleration exposure itself. Plasma PB individual levels ranged between 6 and 31 ng/ml and AChE levels of inhibition had a range of 12 to 45%. There were no significant effects on +Gz tolerance or performance related to PB. Based on the results of this study, PB does not significantly alter +Gz tolerance or performance. Therefore, we do not expect aircrew taking prophylactic doses of PB to be adversely affected during aerial combat operations.
Acceleration↗
G-LOC recovery with and without G-suit inflation.
During acceleration (+Gz) training in the human centrifuge, the anti-G suit (AGS) is usually deflated as acceleration decreases upon termination of the exposure, regardless of the reason for termination, including +Gz-induced loss of consciousness (G-LOC). This is when the trainee most needs the support provided by the AGS. A method to reduce the time of incapacitation resulting from G-LOC was evaluated. The standard CSU15-P suit worn by 30 aircrew while undergoing +Gz tolerance training was inflated to 10 psi immediately upon G-LOC (GS group). Incapacitation times and flailing activity were recorded and compared with 51 aircrew whose AGS was not abruptly inflated upon G-LOC (NGS group). Absolute incapacitation was significantly different between both groups (p = 0.024). The GS group exhibited flailing behavior for a longer period of time during relative incapacitation than the NGS group (p = 0.0003). Total incapacitation remained unaffected. A brief period of confusion occasionally accompanied by mimic or myoclonic convulsions was observed more often in the GS group. Inflation of the AGS upon G-LOC seems to reduce absolute incapacitation by approximately 2 s, thereby causing the trainee to be aware of his environment and G-LOC more quickly, even though his motor function has not yet been fully restored.
Acceleration↗
The effect of G-LOC on psychomotor performance and behavior.
Acceleration (+Gz) induced loss of consciousness (G-LOC) and its effect upon cognitive and motor performance were evaluated in seven male volunteers who were exposed to closed-loop acceleration exposures at the Naval Air Warfare Center--Aircraft Division, Warminster (NAWCADWAR) human centrifuge (DFS). The +Gz profile consisted of several aerial combat environment simulations (ACES) of up to +12 Gz. In the event of G-LOC, the DFS was brought down to a base +Gz level. As the subject recovered consciousness, he was required to complete various tasks to regain control of the aircraft. Psychomotor performance was measured before, immediately after, and 20-40 min post-G-LOC. These tasks included: 1) extinguishing master caution signals initiated upon G-LOC by an observer; 2) entering a control code on a head-down display to initiate DFS trim mode; and 3) matching own aircraft altitude, airspeed and heading to that of a displayed target. Absolute (6 +/- 2 s), relative (5 +/- 3 s) and total (12 +/- 3 s) incapacitations were briefer than those reported in the literature. The time intervals to execute the performance tasks tended to be longer for post-G-LOC than for pre-G-LOC. Recovery of psychomotor performance, as measured in this study, occurred approximately 60 s post G-LOC. There were no performance decrements during those tasks assigned 20-40 min after G-LOC.
Acceleration↗
Physiologic correlates of protection afforded by anti-G suits.
A new uniform-pressure pneumatic anti-G suit (UPS) was compared with the standard CSU-13B/P anti-G suit, using measurements of: blood lactate, heart rate changes, and segmented lower-body blood pooling (by impedance plethysmography). Subjects were exposed to a series of gradual-onset-rate (GOR) runs (0.1 G.s-1), rapid-onset-rate (ROR) runs (6 G.s-1), and simulated aerial combat maneuvers (SACM) on the USAF School of Aerospace Medicine human-use centrifuge. All measured parameters and subjective reports indicated that increased protection was afforded by the UPS. The impedance plethysmography measurements indicated that prevention of blood pooling in all lower-body segments is the predominant mechanism whereby uniform pressure permits significantly longer times-to-fatigue during SACMs.
Adult↗
Dynamic cardiovascular response to +Gz stress in aerobically trained individuals.
Very high onset sustained +Gz stress requires rapid cardiovascular response to support human tolerance. This study was conducted following a previous study concerning +Gz tolerance in aerobically trained individuals, and was initiated to determine if intense aerobic conditioning might affect cardiovascular +Gz tolerance through reduction in heart rate response to +Gz stress. The study compared heart rate response data on 22 aerobically trained runners and 13 less-conditioned individuals. All subjects were exposed to a standard medical evaluation protocol, which consisted of a gradual-onset (0.1 G/s) acceleration exposure (GOR1), followed by a series of rapid-onset (1.0 G/s) acceleration exposures (ROR), a second gradual-onset rate exposure (GOR2), and a third gradual-onset rate exposure with the subjects performing anti-G straining maneuvers (GORS). Aerobic conditioning was not found to be associated with a reduced heart rate response to +Gz stress, compared to the response of unconditioned subjects, when the following variables were considered; heart rate change from rest to maximum exposure heart rate, heart rate change from rest to the heart rate achieved at the onset of maximum G, and the rate of change in heart rate per unit +Gz. Although enhanced parasympathetic tone, induced by long-term aerobic conditioning (running) results in a reduced heart rate at rest and during +Gz stress, it does not alter the responsiveness of the heart rate to +Gz stress.
Acceleration↗
Optimum sampling times for maximum blood lactate levels after exposures to sustained +Gz.
Six male subjects wearing anti-G suits were exposed to +4.5 Gz and +4.5-7 Gz simulated aerial combat maneuvers (SACM), sustained until terminated because of fatigue. Before and after each G exposure, venous blood was withdrawn (using the finger-prick method) and analyzed for lactate concentration. Five samples were taken serially, at 1, 3, 6, 10, and 20 min after each G exposure to determine the maximum (peak) level of blood lactate. Individual lactate levels varied, with peaks at 1, 3, and 6 min; however, group levels were maximum at 3 min after the G exposure. Maximum lactate levels (mean +/- S.D.) of 27.8 +/- 11.3 mg% and 42.7 +/- 19.4 mg% were found for the 4.5-G and SACM exposures, respectively. Lactate recoveries were a simple exponential function, with a half life of approximately 10 min. The relationship between these data, following G exposure, and those measured after aerobic physical activities, is discussed.
Gravitation↗
Reflex heart rate response to variable onset +Gz.
Rapid onset high sustained +Gz is a frequent requirement in air combat maneuvering. The cardiovascular response is inadequate to fully compensate for this rapid +Gz change. The rate of change in heart rate (HR) during gradual (0.1 G.s-1, GOR), rapid (1.0 G.s-1, ROR), and very high (6.0 G.s-1, VHOG) onset acceleration exposures to sustained (15 s) +7Gz, +8Gz, and +9Gz levels was measured in 81 healthy male subjects in a human centrifuge. The time (s) to reach maximum heart rate (T7) was measured as the time for the preacceleration exposure resting heart rate (RHR) to reach maximum heart rate (MHR). The change in heart rate upon reaching maximum +Gz level (delta HRA) from rest was calculated along with the change in HR from rest to the maximum heart rate achieved before maximum +Gz level was attained. During the ROR and VHOG runs, MHR was not achieved until after maximum +Gz level was attained. The change in heart rate from resting HR (immediately prior to acceleration) to the heart rate achieved at the onset of maximum +Gz level (delta HRA), decreased by 50% as the onset rate increased from GOR to ROR and VHOG. The delta HRB for very high onset rates exposures was significantly greater than that for ROR and GOR exposures. Acceleration exposure to levels of +7Gz and above (+7Gz, +8Gz and +9Gz) exhibited similar HR responses. VHOG to sustained +Gz stress levels of +7 to +9Gz for 15 s did not provide a sufficient length of time to allow maximum cardiovascular response.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Recovery from Gz-induced loss of consciousness: psychophysiologic considerations.
Eight healthy male volunteer members of the USAFSAM acceleration panel were exposed to two consecutive acceleration runs of +1 Gz to +7 Gz at 6 G.s-1 onset rates. The subjects were instructed to relax during the acceleration exposure in order to voluntarily induce loss of consciousness (LOC). The subjects were asked to relate dreams, thoughts, or other mental illusions experienced during G-LOC episodes. Most subjects were amused and surprised, as well as interested in, relating their experience, although they were embarrassed about the G-LOC episode itself. Early post-G-LOC transient paralysis, as well as late LOC myoclonic (flailing) movements, were evident. Heart-rate response to the acceleratory stress was uneventful; maximum heart rate occurred 3.2 s after the onset of LOC. The study of dreams during normal sleep stages has been reviewed by many investigators, but this research has not extended to acceleration/hypoxic types of unconsciousness where dreams also seem to occur. G-LOC dream-state analysis, post-G-LOC paralysis, and their possible repercussions upon performance and incapacitation periods should be investigated, not only as curious events, but as operationally important and psychophysiologically significant.
Acceleration↗
Anaerobic energetics of the simulated aerial combat maneuver (SACM).
The role of anaerobic metabolism in +Gz duration tolerance was measured using venous blood lactate concentrations before G exposure and after subjects had been fatigued from exposure to one of several levels of G: low (4.5 G) sustained G (LSG); high (7-9 G) sustained G (HSG); and simulated aerial combat maneuver (SACM) of 4.5/7 G levels. A mean +/- S.E. blood lactate of six subjects fatigued from LSG was 29.8 +/- 4.0 mg%. Four subjects fatigued from HSG had blood lactates of 42.4 +/- 3.2 mg%, and six had blood lactates of 46.7 +/- 7.2 mg% from the SACM. Blood lactates appeared to correlate directly (on a group basis) with maximum heart rates found during G exposures. Six subjects exposed to 8 or 9 G for 10 s or less demonstrated an anaerobic alactate capacity. These G findings were related to fatigue produced with isometric muscle contraction in physiologic studies conducted at 1 G. We concluded that anaerobic metabolism and isometric exercise physiology are directly related to duration tolerances of fatigue at all levels of +Gz.
Aerospace Medicine↗