BACKGROUND: Current studies have focused mainly on the push-pull effect (PPE), the reduction of +Gz tolerance when hypergravity (>+1 Gz) preceded by hypogravity (<+1 Gz). However, the reduced G tolerance could be induced by any G-transition. The frequency and extent of maneuvers to cause G-transition effect (GTEM) have not been studied previously in fighter aircraft. METHODS: 26 HUD (head-up display) videotapes from F-16 aerial combat training missions were reviewed for the presence of GTEM. The frequency and magnitude of the +Gz profiles were analyzed. RESULTS: GTEMs were found in 34 (29.6%) of 115 engagements reviewed. PPEMs (maneuvers found to cause push-pull effect) and rPPEMs (maneuvers found to cause reversed PPE) were found in 7.8%, 11.3% respectively. Combined maneuver that rPPEM followed by PPEM consecutively was found in 10.4% of engagements. There was no difference the frequency of GTEMs between BFM and ACM engagements (28.8% vs. 30.9%). CONCLUSION: GTEMs including PPEMs and rPPEMs are present in aerial combat training missions of F-16 aircraft and represent a significant source for accidents. These findings support the necessity of continued research into the physiologic response to GTE.
Aircraft* ; Humans ; Hypergravity ; Hypogravity ; Missions and Missionaries* ; Videotape Recording

Prior research reported the oscillatory behavior characterized by long period and high amplitude during high gravity continuous ethanol fermentations at the dilution rate of 0.027 h(-1). In this paper, high gravity continuous ethanol fermentations using Saccharomyces cerevisia at different dilution rates were carried out. Similar oscillations were observed when the dilution rate was switched to 0.04 h(-1). Both oscillatory and steady processes can be achieved at dilution rates of 0.027 or 0.04 h(-1), which depends on the initial status of the fermentation system. However, compared to steady process at the same dilution rate of 0.04 h(-1), the average residual sugar concentration was lowered by 14.8% for the oscillatory process, while the average ethanol concentration and productivity were increased by 12.6% and 12.3%, respectively. Further investigation revealed that besides the lag time, oscillatory processes were different from steady ones in kinetics because a higher specific growth rate can be achieved at the same residual sugar and ethanol concentrations (increased by 53.8% in average).
Bioreactors ; microbiology ; Carbohydrates ; Ethanol ; metabolism ; Fermentation ; Hypergravity ; Saccharomyces cerevisiae ; metabolism

As a new beer fermentation technology, high temperature and high gravity fermentation has brought many benefits to brewery industry, but there are also a series of problems such as the decrease of yeast flocculation ability at the end of fermentation and the high concentration of higher alcohols. To increase yeast flocculation ability and reduce the production of higher alcohols in high temperature and high gravity fermentation of beer, BAT2 was replaced by the FLO5 expression cassette to obtain the mutant strain S6-BF2. Real-time quantitative PCR showed that the relative transcriptional level of FLO5 in S6-BF2 improved 17.8 times compared with that in S6. The flocculation ability of mutant S6-BF2 heightened by 63% compared to that of the original strain S6, and the concentration of higher alcohols decreased from 175.58 mg/L to 159.58 mg/L in high temperature and high gravity fermentation of beer. Moreover, the activity of mitochondrial branched-chain amino acid transferase was repressed, resulting in the production of higher alcohols of 142.13 mg/L, reduced by 18.4% compared to that of the original strain S6, meanwhile, the flocculation ability of mutant S6-BF2B1 kept unchanged compared to the mutant S6-BF2. The determination result of flavor compounds showed that the higher alcohols/ester ratio in beer was reasonable. This research has suggested an effective strategy for enhancing yeast flocculation ability and decreasing production of higher alcohols in high-temperature and high-gravity brewing.
Beer ; Fermentation ; Hypergravity ; Saccharomyces cerevisiae ; Saccharomyces cerevisiae Proteins ; Temperature ; Transaminases

Continuous ethanol fermentation using very high gravity medium containing 280 g/L glucose, 5 g/L yeast extract and 3 g/L peptone was run at the dilute rates of 0.006 h(-1), 0.012 h(-1), 0.017 h(-1), 0.024 h(-1) and 0.032 h(-1) (based on the total working volume) in a combined bioreactor system composed of a stirred tank and three-stage tubular bioreactors in series. Oscillations marked by big fluctuations of residual glucose, ethanol and biomass were observed at the dilution rate of 0.012 h(-1). The Hopf Bifurcation theory was used to analyze and predict the occurring of these oscillations and the dilution rates that incited oscillations. Theoretical analysis revealed that oscillations can occur at designated specific growth rates and was validated by experimental results. The benefits of oscillations for the fermentation system were also discussed by comparing the fermentation results with those without oscillations.
Bioreactors ; microbiology ; Ethanol ; metabolism ; Fermentation ; Glucose ; metabolism ; Hypergravity ; Saccharomyces cerevisiae ; metabolism

AIMTo investigate the +Gz protection provided by tilt-back seat and GZ-2 anti-G suit.

METHODS6 subjects were exposed to centrifuge and onset rate is 3 G/s. First, their relaxed +Gz tolerances were determined while using tilt-back seat of 13 degrees. Secondly, it was their +Gz tolerance provided by pressurized GZ-2 anti-G suit and tilt-back seat of 13 degrees. Finally, their +Gz tolerances while using pressurized GZ-2 anti-G suit and tilt-back seat of 45 degrees were determined. The difference between the first and the third result was the +Gz protection that pressurized GZ-2 anti-G suit and tilt-back seat of 45 degrees offered.

RESULTS+Gz protection of pressurized GZ-2 anti-G suit and tilt-back seat of 13 degrees was 3.06 G, and +Gz protection of pressurized GZ-2 anti-G suit and tilt-back seat of 45 degrees was 4.13 G, which had an increase of 1.06 G.

CONCLUSIONTilt-back seat of 45 degrees can greatly enhance +Gz tolerances of human.

Adolescent ; Aerospace Medicine ; instrumentation ; methods ; Centrifugation ; Gravity Suits ; Humans ; Hypergravity ; Male ; Posture ; Protective Clothing ; Young Adult

Hypergravity has been shown to affect the human physiology, especially the kidney and heart. The kidney is affected during or after tests on positive acceleration. PRA was increased after positive acceleration. ANP has inverse relationship with renin, which has sodium and water retention. The experiment was design to investigate possible ANP decrease and changes in function and structure of the testis, kidney after exposure to 9G, 120 sec positive acceleratory forces as imposed on rat by the Human Centrifuge. As result, positive radial acceleration has made no change in concentration of ANP in statistically with increasing PRA, After acceleration, the glomerulus of the kidney showed no ischemic changes, but tubule of the kidney showed containing of cast. The seminiferous tubule of the testis showed normal.
Acceleration* ; Animals ; Atrial Natriuretic Factor ; Heart ; Humans ; Hypergravity ; Kidney* ; Physiology ; Plasma* ; Rats ; Renin* ; Seminiferous Tubules ; Sodium ; Testis*

While injuries to the spine after an airplane crash are not rare, most crashes result in fatal injuries. As such, few studies exist that reported on spine fractures sustained during airplane accidents. In this report, we demonstrate three cases of spine fractures due to crash landing of a commercial airplane. Three passengers perished from injuries after the crash landing, yet most of the passengers and crew on board survived, with injuries ranging from minor to severe. Through evaluating our three spine fracture patients, it was determined that compression fracture of the spine was the primary injury related to the airplane accident. The first patient was a 20-year-old female who sustained a T6-8 compression fracture without neurologic deterioration. The second patient was a 33-year-old female with an L2 compression fracture, and the last patient was a 49-year-old male patient with a T8 compression fracture. All three patients were managed conservatively and required spinal orthotics. During the crash, each of these patients were subjected to direct, downward high gravity z-axis (Gz) force, which gave rise to load on the spine vertically, thereby causing compression fracture. Therefore, new safety methods should be developed to prevent excessive Gz force during airplane crash landings.
Accidents, Aviation ; Adult ; Aircraft* ; Back Pain ; Female ; Fractures, Compression ; Humans ; Hypergravity ; Male ; Middle Aged ; Spinal Fractures ; Spine* ; Young Adult

With the development of high gravity brewing, yeast cells are exposed to multiple brewing-associated stresses, such as increased osmotic pressure, enhanced alcohol concentration and nutritional imbalance. These will speed up yeast autolysis, which seriously influence beer flavor and quality. To increase yeast anti-autolytic ability, FKS1 overexpression strain was constructed by 18S rDNA. The concentration of β-1,3-glucan of overexpression strain was 62% higher than that of wild type strain. Meantime, FKS1 overexpression strain increased anti-stress ability at 8% ethanol, 0.4 mol/L NaCl and starvation stress. Under simulated autolysis, FKS1 showed good anti-autolytic ability by slower autolysis. These results confirms the potential of FKS1 overexpression to tackle yeast autolysis in high-gravity brewing.
Autolysis ; Beer ; Echinocandins ; genetics ; Glucosyltransferases ; genetics ; Hypergravity ; Membrane Proteins ; genetics ; Saccharomyces cerevisiae ; cytology ; Saccharomyces cerevisiae Proteins ; genetics

OBJECTIVES: We aimed to study the role of vestibular input on spatial memory performance in mice that had undergone bilateral surgical labyrinthectomy, semicircular canal (SCC) occlusion and 4G hypergravity exposure. METHODS: Twelve to 16 weeks old ICR mice (n=30) were used for the experiment. The experimental group divided into 3 groups. One group had undergone bilateral chemical labyrinthectomy, and the other group had performed SCC occlusion surgery, and the last group was exposed to 4G hypergravity for 2 weeks. The movement of mice was recorded using camera in Y maze which had 3 radial arms (35 cm long, 7 cm high, 10 cm wide). We counted the number of visiting arms and analyzed the information of arm selection using program we developed before and after procedure. RESULTS: The bilateral labyrinthectomy group which semicircular canal and otolithic function was impaired showed low behavioral performance and spacial memory. The semicircular canal occlusion with CO₂ laser group which only semicircular canal function was impaired showed no difference in performance activity and spatial memory. However the hypergravity exposure group in which only otolithic function impaired showed spatial memory function was affected but the behavioral performance was spared. The impairment of spatial memory recovered after a few days after exposure in hypergravity group. CONCLUSIONS: This spatial memory function was affected by bilateral vestibular loss. Space-related information processing seems to be determined by otolithic organ information rather than semicircular canals. Due to otolithic function impairment, spatial learning was impaired after exposure to gravity changes in animals and this impaired performance was compensated after normal gravity exposure.
Animals ; Arm ; Automatic Data Processing ; Gravitation ; Hypergravity ; Memory ; Mice ; Mice, Inbred ICR ; Otolithic Membrane ; Semicircular Canals ; Spatial Learning ; Spatial Memory

OBJECTIVETo study the effects of repeated + Gz forces on masticatory muscles.

METHODS48 male Wistar rats were randomly divided into 4 groups. Group A was normally fed. Group B was only fixed with rat-kept devices for 5 minutes. Group C was borne + 1 Gz for 5 minutes. Group D was repeatedly exposed + 10 Gz (each for 30 s, onset rate about 0.5 G/s, 5 times/d with + 1 Gz 1 minute intervals, 4 d/wk, 3 weeks in total). The histological changes of the masseter, temporal and lateral pterygoid muscles were observed.

RESULTSNo abnormal changes were observed in Group A, B and C. But pathological changes could be found in group D. The wrench and deformation of muscular fibers, the dissolution of partial myofibril, the swelling of mitochondria, the reduce of hepatin from the masseter and lateral pterygoid muscles could be found.

CONCLUSIONSRepeated + Gz stresses could induce the damage of masticatory muscles in different degrees.

Animals ; Hypergravity ; Male ; Masseter Muscle ; pathology ; ultrastructure ; Masticatory Muscles ; pathology ; ultrastructure ; Microscopy, Electron ; Pterygoid Muscles ; pathology ; ultrastructure ; Rats ; Rats, Wistar ; Temporal Muscle ; pathology ; ultrastructure ; Time Factors