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Sample records for 6 deg head-down

  1. Back Pain During 6 deg Head-Down Tilt Approximates That During Actual Microgravity

    NASA Technical Reports Server (NTRS)

    Hutchinson, Karen J.; Watenpaugh, Donald E.; Murthy, Gita; Convertino, Victor A.; Hargens, Alan R.

    1995-01-01

    Astronauts often experience back pain during spaceflight. It was found that during spaceflight, 14 of 19 Shuttle crewmembers experienced back pain, which they described as dull (62%), localized to the lower back (500/6), and with an intensity of 2 on a 5-point scale. Further, the spine lengthens 4-7 cm in microgravity. Our objective was to compare back pain and spinal lengthening (body height increase) during simulated microgravity (6 deg head-down tilt, HDT) with the some parameters during actual microgravity. Eight male subjects completed a modified McGill pain questionnaire with intensity graded from zero (no pain) to five (intense and incapacitating gain) each day at 7.-OO pm during 2 d pre-HDT control, 16 d HDT, and I d post-HDT recovery periods. Only 2 subjects reported any pain after day 9 of HDT and during recov- ery. Heights increased 2.1 t 0.5 cm by day 3 of HDT and re- mained at that level until the end of the HDT period. Although spinal lengthening in space is greater than that during HDT, the HDT model approximates the level, type, distribution, and time course of back pain associated with actual microgrovity. In the HDT model, pain subsides in intensity when spinal lengthening stops. Therefore, back pain in actual and simulated microgravity may result from stretching of spinal andlor paraspinal tissues until a new spinal length is reached.

  2. Effect of leg exercise training on vascular volumes during 30 days of 6 deg head-down bed rest

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Vernikos, J.; Wade, C. E.; Barnes, P. R.

    1992-01-01

    In order to investigate the effects of leg exercise training on vascular volumes during 30 d of 6-deg head-down bed rest, plasma and red cell volumes, body density, and water balance were measured in 19 men confined to bed rest (BR). One group had no exercise training (NOE), another near-maximal variable-intensity isotonic exercise (ITE) for 60 min/d, and the third near-maximal intermittent isokinetic exercise (IKE) for 60 min/d. Mean energy costs for the NOE, IKE, and ITE regimens were determined. Body densities within groups and mean urine volumes between groups were unchanged during BR. Changes in red cell volume followed changes in plasma volume. There was close coupling between resting plasma volume and plasma protein and osmotic content. It is argued that the ITE training protocol is better than the IKE protocol for maintaining plasma volume during prolonged exposure to BR.

  3. Gender differences in endocrine responses to posture and 7 days of 6 deg head down bed rest

    NASA Technical Reports Server (NTRS)

    Vernikos, J.; Dallman, M. F.; Keil, L. C.; Ohara, D.; Convertino, V. A.

    1993-01-01

    Endocrine regulation of fluids and electrolytes during seven days of 6 deg head down bed rest (HDBR) was compared in male (n = 8) and, for the first time, female (n = 8) volunteers. The subjects' responses to quiet standing for 2 hr before and after HDBR were also tested. In both sexes, diuresis and natriuresis were evident during the first 2-3 days of HDBR, resulting in a marked increase in the urinary Na/K ratio and significant Na retention on reambulation. After the first day of HDBR, plasma renin activity (PRA) was increased relative to aldosterone, plasma volume was decreased, and the renal response to aldosterone appeared to be appropriate. Circulating levels of arginine vasopressin (AVP), cortisol, and ACTH were unchanged during HDBR. Plasma testosterone decreased slightly on day 2 of HDBR in males. The ratio of AM ACTH to cortisol was lower in females than in males because ACTH was lower in females. Urinary cortisol increased and remained elevated throughout the HDBR in males only. There were no gender differences in the responses to 7 day HDBR, except those in the pituitary-adrenal system; those differences appeared unrelated to the postural change. The provocative cardiovascular test of quiet standing before and after bed rest revealed both sex differences and effects of HDBR. There were significant sex differences in cardiovascular responses to standing, before and after HDBR. Females had greater PRA and aldosterone responses to standing before bedrest and larger aldosterone responses to standing after HDBR than males. Cardiovascular responses to standing before and after bedrest differed markedly: arterial pressure and heart rates increased with standing before HDBR, by contrast, arterial pressure decreased, with greater increases in heart rates after HDBR. In both sexes, all hormonal responses to standing were greater after HDBR. The results show clearly that similar responses to standing as well as to HDBR occur in both sexes, but that females exhibit

  4. Exercise Thermoregulation After 6 hours of Chair Rest, 6 deg Head-Down Bed-Rest, and Water Immersion Deconditioning in Men

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Hutchinson, T.; Shaffer-Bailey, M.; Looft-Wilson, R.

    1996-01-01

    The purpose was to investigate the mechanism for the excessive exercise hyperthermia following deconditioning (reduction of physical fitness). Rectal (T(sub re)) and mean skin (T(bar)(sub sk)) temperatures and thermoregulatory responses were measured in six men [mean (SD) age, 32 (6) years; mass, 78.26 (5.80) kg; surface area, 1.95 (0.11) sq m; maximum oxygen uptake (VO2max), 48 (6) ml/min/kg; whilst supine in air at dry bulb temperature 23.2 (0.6)C, relative humidity 31.1 (11.1)% and air speed 5.6 (0.1) m/min] during 70 min of leg cycle exercise [51 (4)% VO2max] in ambulatory control (AC), or following 6 h of chair rest (CR), 6deg head-down bed rest (BR), and 20deg (W120) and 80deg (W180) foot-down water immersion [water temperature, 35.0 (0.1) C]. Compared with the AC exercise (Delta)T(sub re) [mean (SD) 0.77 (0.13)C], (Delta)T(sub re), after CR was 0.83 (0.08)C (NS), after BR 0.92 (0.13)C (*P <0.05), after W180 0.96 (0.13)C*, and after W120 1.03 (0.09)C*. All T(sub sk) responded similarly to exercise: they decreased (NS) by 0.5-0.7 C in minutes 4-8 and equilibrated at +0.1 to +0.5 C at 60-70. Skin heat conductance was not different among the five conditions (range = 147-159 kJ/sq/C. Results from an intercorrelation matrix suggested that total body sweat rate was more closely related to T(sub re) at 70 min (T(sub re70)) than limb sweat rate or blood flow. Only 36% of the variability in T(sub re70) could be accounted for by total sweating, and less than 10% from total body dehydration. It would appear that multiple factors are involved which may include change in sensitivity of thermo- and osmoreceptors.

  5. Knee-Joint Proprioception During 30-Day 6 deg Head-Down Bed Rest with Isotonic and Isokinetic Exercise Training

    NASA Technical Reports Server (NTRS)

    Bernauer, E. M.; Walby, W. F.; Ertl, A. C.; Dempster, P. T.; Bond, M.; Greenleaf, J. E.

    1994-01-01

    To determine if daily isotonic exercise or isokinetic exercise training coupled with daily log proprioceptive training, would influence log proprioceptive tracking responses during Bed Rest (BR), 19 men (36 +/- SD 4 years, 178 +/- 7 cm, 76.8 +/- 7.8 kg) were allocated into a NO-Exercise (NOE) training control group (n = 5), and IsoTanic Exercise (ITE, n = 7) and IsoKinetic Exercise (IKE, n = 7) training groups. Exercise training was conducted during BR for two 30-min period / d, 5 d /week. Only the IKE group performed proprioceptive training using a now isokinetic procedure with each lower extremity for 2.5 min before and after the daily exercise training sessions; proprioceptive testing occurred weekly for all groups. There were no significant differences in proprioceptive tracking scores, expressed as a percentage of the perfect score of 100, in the pro-BR ambulatory control period between the three groups. Knee extension and flexion tracking responses were unchanged with NOE during BR, but were significantly greater (*p less than 0.05) at the end of BR in both exercise groups when compared with NOE responses (extension: NOE 80.7 +/- 0.7%, ITE 82.9 +/- 0.6%, IKE 86.5* +/- 0.7%; flexion: NOE 77.6 +/- 1.50, ITE 80.0 +/- 0.8% (NS), IKE 83.6* +/- 0.8%). Although proprioceptive tracking was unchanged during BR with NOE, both lsotonic exercise training (without additional propriaceptive training) and especially isokinetic exercise training when combined with daily proprioceptive training, significantly improved knee proprioceptive tracking responses after 30 d of BR.

  6. Association Between Cardiovascular and Intraocular Pressure Changes in a 14-Day 6 deg Head Down Tilt (HDT) Bed Rest Study: Possible Implications in Retinal Anatomy

    NASA Technical Reports Server (NTRS)

    Cromwell, Ronita; Zanello, Susana; Yarbough, Patrice; Ploutz-Snyder, Robert; Taibbi, Giovanni; Vizzeri, Gianmarco

    2013-01-01

    Visual symptoms and intracranial pressure increase reported in astronauts returning from long duration missions in low Earth-orbit are thought to be related to fluid shifts within the body due to microgravity exposure. Because of this possible relation to fluid shifts, studies conducted in head-down tilt (HDT) bed rest are being monitored for potential changes in ocular health. These measures will also serve to determine whether HDT is a suitable ground-based analog to model subclinical cardiovascular and ocular changes that could shed light on the etiology of the VIIP syndrome observed in spaceflight. Sixteen healthy normotensive (12M, 4F, age range 29-54 years), non-smoker and normal weight subjects, volunteered to participate in a 14 day 6 deg head HDT study conducted at the NASA Flight Analogs Research Unit (FARU). This facility provides standard bed rest conditions (diet, wake/sleep time, time allowed in sunlight) during the time that the subjects stay at the FARU. Cardiovascular parameters were obtained in supine posture at BR-5, BR+0, and BR+3 and ocular monitoring was performed weekly. Intraocular pressure (IOP) increased from pre-bed rest BR-3) to the third day into bed rest (BR+3). Values reached a plateau towards the end of the bed rest phase (BR10) and decreased within the first three days of recovery (BR+2) returning to levels comparable to baseline at BR-3. As expected, most cardiovascular parameters were affected by 14 days of HDT bed rest. Plasma volume decreased as a result of bed rest but recovered to baseline levels by BR+3. Indications of cardiovascular deconditioning included increase in both systolic and diastolic blood pressure and heart rate, and a decrease in stroke volume and cardiac output between BR-5 and BR+3. Due to the experimental design of this study, we were not able to test the hypothesis that fluid shifts might be involved in the IOP increase during the bed rest phase, since cardiovascular measures were not available for those

  7. Spectral components of human cardiovascular responses to step changes in Lower Body Negative Pressure (LBNP) before and after 22 hour of 6 deg head down bed rest

    NASA Technical Reports Server (NTRS)

    Knapp, C. F.; Evans, J. M.; Grande, K. J.; Murphy, C. D.; Patwardhan, A. R.

    1992-01-01

    Changes in autonomic outflow to peripheral organs during the development of bedrest induced orthostatic intolerance have not been determined. Recent studies have indicated that spectral analysis provides an indirect assessment of these changes. Eight male subjects were studied before and after 22 hours of 6 degree head down bedrest plus Lasix (40 mg. P.P.). Cardiovascular spectra (using an autoregressive technique) were determined for heart rate (HR, ECG), arterial pressure (AP, Finapres), radial artery flow (RF, Hokansen) and respiration rate (RR, BoMed). Spectra were obtained from 2.5 minute segments during control, lower body negative pressure (minus 10, 20, 30, 40, 50 mmHg) and recovery. Bedrest increased HR spectra power in the low frequency (.001 to .041 Hz) range, increased RF power in the low and mid (.04 to .18 Hz) range and increased AP power in the high (.18 to .50 Hz) frequency range. Increasing levels of lower body negative pressure decreased HR power and increased RF power in the high frequency range and decreased AP power in the low frequency range. Since spectral power of HR in the high frequency range has been shown to indicate parasympathetically mediated regulation and power in the low and mid frequency ranges indicates a sympathetic / parasympathetic mixture, then both bedrest and lower body negative pressure appeared to shift sympathetic / parasympathetic balance toward sympathetic regulation of HR. The interpretation of the spectral content of AP and RF with respect to their autonomic origins remains unclear.

  8. Association Between Cardiovascular and Intraocular Pressure Changes in a 14-day 6 deg Head Down Tilt (HDT) Bed Rest Study: Possible Implications in Retinal Anatomy

    NASA Technical Reports Server (NTRS)

    Cromwell, R. L.; Zanello, S. B.; Yarbough, P. O.; Ploutz-Snyder, R.; Taibbi, G.; Brewer, J. L.; Vizzeri, G.

    2013-01-01

    Mean IOP significantly increased while at 6deg HDT and returned towards pre-bed rest values upon leaving bed rest. While mean IOP increased during bed rest, it remained within the normal limits for subject safety. A diuretic shift and cardiovascular deconditioning occurs during in-bed rest, as expected. There was no demonstrable correlation between the largest change in IOP (pre/post) and cardiovascular measure changes (pre/post). Additional mixed effects linear regression modeling may reveal some subclinical physiological changes that might assist in describing the VIIP syndrome pathophysiology.

  9. Arterial Pressure Gradients during Upright Posture and 30 deg Head Down Tilt

    NASA Technical Reports Server (NTRS)

    Sanchez, E. R; William, J. M.; Ueno, T.; Ballard, R. E.; Hargens, A. R.; Holton, Emily M. (Technical Monitor)

    1997-01-01

    Gravity alters local blood pressure within the body so that arterial pressures in the head and foot are lower and higher, respectively, than that at heart level. Furthermore, vascular responses to local alterations of arterial pressure are probably important to maintain orthostatic tolerance upon return to the Earth after space flight. However, it has been difficult to evaluate the body's arterial pressure gradient due to the lack of noninvasive technology. This study was therefore designed to investigate whether finger arterial pressure (FAP), measured noninvasively, follows a normal hydrostatic pressure gradient above and below heart level during upright posture and 30 deg head down tilt (HDT). Seven healthy subjects gave informed consent and were 19 to 52 years old with a height range of 158 to 181 cm. A Finapres device measured arterial pressure at different levels of the body by moving the hand from 36 cm below heart level (BH) to 72 cm above heart level (AH) in upright posture and from 36 cm BH to 48 cm AH during HDT in increments of 12 cm. Mean FAP creased by 85 mmHg transitioning from BH to AH in upright posture, and the pressure gradient calculated from hydrostatic pressure difference (rho(gh)) was 84 mmHg. In HDT, mean FAP decreased by 65 mmHg from BH to AH, and the calculated pressure gradient was also 65 mmHg. There was no significant difference between the measured FAP gradient and the calculated pressure gradient, although a significant (p = 0.023) offset was seen for absolute arterial pressure in upright posture. These results indicate that arterial pressure at various levels can be obtained from the blood pressure at heart level by calculating rho(gh) + an offset. The offset equals the difference between heart level and the site of measurement. In summary, we conclude that local blood pressure gradients can be measured by noninvasive studies of FAP.

  10. Comparison of susceptibility to motion sickness during rotation at 30 rpm in the earth-horizontal, 10 deg head-up, and 10 deg head-down positions

    NASA Technical Reports Server (NTRS)

    Graybiel, A.; Lackner, J. R.

    1977-01-01

    Normal persons rotated about an earth-horizontal axis vary in their susceptibility to motion sickness. An experimental study was conducted to measure intraindividual differences in susceptibility in 12 subjects when rotated 10 deg head up and 10 deg head down as well as in the horizontal position. Subjects assumed the test-position 60 min prior to rotation, thus providing an opportunity for translocation of body fluids. Physiological and psychological measurements were conducted throughout the experiment. There were no intraindividual differences in susceptibility to motion sickness in the three positions tested, although there were significant differences in vital capacity, demonstrating the expected fluid shifts. It was concluded that, in the sample of subjects tested, short-term effects of fluid shifts greater than those that would be manifested in zero gravity had no definite effect on motion sickness susceptibility.

  11. An evaluation of the lower coverage anti-G suit without an abdominal bladder after 3 days of 7 deg head down tilt

    NASA Technical Reports Server (NTRS)

    Stegmann, B. J.; Krutz, R. W.; Burton, R. R.; Sawin, C. F.

    1992-01-01

    Twelve healthy male subjects were initially deconditioned by 3 days of 7 deg head down tilt bed rest followed by donning the reentry anti-G suit and being centrifuged using a simulated Shuttle reentry profile. For 6 of the 12 subjects, anti-G suit pressure was increased in 0.5 psig increments if eye level blood pressure dropped below 70 mmHg. The second half of the subjects had their G-suits inflated in 0.5 psig increments if they reported 50 percent peripheral light dimming. Results show that the maximum allowable pressure for either exposure was 2.5 psig, which is the operational limit of the Shuttle anti-G suit controller.

  12. The influence on individual working memory during 15 days -6° head-down bed rest

    NASA Astrophysics Data System (ADS)

    Zhao, Xin; Wang, YiXue; Zhou, RenLai; Wang, LinJie; Tan, Cheng

    2011-12-01

    The research evaluated the changes of verbal and spatial working memory with females during 15 days -6° head-down bed rest. We used 2-back task to evaluate the working memory ability on four time points: the fifth day before the rest, the fifth day and the tenth day in the rest and the fifth day after the rest, as well as record the participants' depression and anxiety feelings using Beck Anxiety Inventory (BAI) and Beck Depression Inventory (BDI) simultaneously. The results demonstrated that the trends of verbal and spatial working memory performance were consistent with that of the control group during the rest. Moreover, in the -6° head-down bed rest conditions, the participants have performed no damage on the working memory ability, and any clinically salient anxiety and depression. The research considered that, compared to the real space environment, individuals' undamaged cognitive functions probably have something to do with the failure of evoking clinical anxiety and depression in the stimulated weightless environment.

  13. Exercise thermoregulation in men after 1 and 24-hours of 6 degrees head-down tilt

    NASA Technical Reports Server (NTRS)

    Ertl, A. C.; Dearborn, A. S.; Weidhofer, A. R.; Bernauer, E. M.; Greenleaf, J. E.

    2000-01-01

    BACKGROUND: Exercise thermoregulation is dependent on heat loss by increased skin blood flow (convective and conductive heat loss) and through enhanced sweating (evaporative heat loss). Reduction of plasma volume (PV), increased plasma osmolality, physical deconditioning, and duration of exposure to simulated and actual microgravity reduces the ability to thermoregulate during exercise. HYPOTHESIS: We hypothesized that 24 h of head down tilt (HDT24) would alter thermoregulatory responses to a submaximal exercise test and result in a higher exercise rectal temperature (Tre) when compared with exercise Tre after 1 h of head down tilt (HDT1). METHODS: Seven men (31+/-SD 6 yr, peak oxygen uptake (VpO2peak) of 44+/-6 ml x kg(-1) x min(-1)) were studied during 70 min of supine cycling at 58+/-SE 1.5% VO2peak at 22.0 degrees C Tdb and 47% rh. RESULTS: Relative to pre-tilt sitting chair rest data, HDT1 resulted in a 6.1+/-0.9% increase and HDT24 in a 4.3+/-2.3% decrease in PV (delta = 10.4% between experiments, p<0.05) while plasma osmolality remained unchanged (NS). Pre-exercise Tre was elevated after HDT24 (36.71 degrees C +/-0.06 HDT1 vs. 36.93 degrees C+/-0.11 HDT24, p<0.05). The 70 min of exercise did not alter this relationship (p<0.05) with respective end exercise increases in Tre to 38.01 degrees C and 38.26 degrees C (degrees = 1.30 degrees C (HDT1) and 1.33 degrees C (HDT24)). While there were no pre-exercise differences in mean skin temperature (Tsk), a significant (p<0.05) time x treatment interaction occurred during exercise: after min 30 in HDT24 the Tsk leveled off at 31.1 degrees C, while it continued to increase reaching 31.5 degrees C at min 70 in HDT1. A similar response (NS) occurred in skin blood velocity. Neither local sweating rates nor changes in body weight during exercise of -1.63+/-0.24 kg (HDT1) or - 1.33+/-0.09 kg (HDT24) were different (NS) between experiments. CONCLUSION: While HDT24 resulted in elevated pre-exercise Tre, reduced PV

  14. Changes in prevalence of subjective fatigue during 14-day 6° head-down bed rest

    NASA Astrophysics Data System (ADS)

    Hirayanagi, Kaname; Natsuno, Toyoki; Shiozawa, Tomoki; Yamaguchi, Nobuhisa; Watanabe, Yoriko; Suzuki, Satomi; Iwase, Satoshi; Mano, Tadaaki; Yajima, Kazuyoshi

    2009-06-01

    The present study examines the prevalence of subjective fatigue in young healthy males during 14 days of 6° head-down bed rest (HDBR) by using a multidimensional questionnaire. Forty-one subjects completed the Subjective Fatigue Scale questionnaire to assess the fatigue-related complaints and symptoms. The questionnaire is composed of three sections, with 10 items each. The sections measured drowsiness and dullness (Section 1), difficulty in concentration (Section 2), and the projection of physical disintegration (Section 3). The subjects answered simple questions between 1400 and 1700 on 6 measurement days before and during the HDBR period. The prevalence rate of low back pain was markedly high (80.5%) on the second day and more than 50% in the first half of the HDBR period, and any complaints related to either a lack of sleep or a deterioration in the quality of sleep continued until the end of the HDBR period. Our findings may be useful in developing preventive strategies against physical and mental fatigue associated with prolonged HDBR, horizontal bed rest, and microgravity environments.

  15. Height increase, neuromuscular function, and back pain during 6 degrees head-down tilt with traction

    NASA Technical Reports Server (NTRS)

    Styf, J. R.; Ballard, R. E.; Fechner, K.; Watenpaugh, D. E.; Kahan, N. J.; Hargens, A. R.

    1997-01-01

    BACKGROUND: Spinal lengthening and back pain are commonly experienced by astronauts exposed to microgravity. METHODS: To develop a ground-based simulation for spinal adaptation to microgravity, we investigated height increase, neuromuscular function and back pain in 6 subjects all of whom underwent two forms of bed rest for 3 d. One form consisted of 6 degrees of head-down tilt (HDT) with balanced traction, while the other was horizontal bed rest (HBR). Subjects had a 2-week recovery period in between the studies. RESULTS: Total body and spinal length increased significantly more and the subjects had significantly more back pain during HDT with balanced traction compared to HBR. The distance between the lower endplate of L4 and upper endplate of S1, as measured by ultrasonography, increased significantly in both treatments to the same degree. Intramuscular pressures in the erector spinae muscles and ankle torque measurements during plantarflexion and dorsiflexion did not change significantly during either treatment. CONCLUSION: Compared to HBR, HDT with balanced traction may be a better method to simulate changes of total body and spinal lengths, as well as back pain seen in microgravity.

  16. Effect of 6 degrees head-down tilt on cardiopulmonary function: comparison with microgravity

    NASA Technical Reports Server (NTRS)

    Prisk, G. Kim; Fine, Janelle M.; Elliott, Ann R.; West, John B.

    2002-01-01

    BACKGROUND: Head-down tilt (HDT) of 6 degrees is a commonly used model of weightlessness, but there are few comparisons with actual microgravity. HYPOTHESIS: Our study was designed to prove that the changes in cardiopulmonary function seen in HDT would be similar to those seen in microgravity. METHODS: We compared measurements of cardiovascular and pulmonary function from three separate spaceflights of 14 to 17 d duration, with data collected during a 17-d period of HDT. RESULTS: HDT proved a good model of the cardiovascular response to microgravity, resulting in increases in cardiac output and stroke volume of a similar magnitude to those seen in microgravity, with a concomitant reduction in heart rate. By contrast, HDT was a poor model of the effects of microgravity on pulmonary ventilation and gas exchange. CONCLUSION: Pulmonary function in HDT approximated the changes seen in the 1-G supine posture, while in microgravity this was much closer to that seen in the 1-G upright position. The differences probably reflect the fact that changes in cardiovascular function result primarily from fluid shifts within the entire body, whereas changes in pulmonary ventilation are primarily a result of mechanical influences on the lung and chest and abdominal wall.

  17. Can daily centrifugation prevent the haematocrit increase elicited by 6-degree, head-down tilt?

    PubMed

    Yajima, K; Iwasaki, K; Sasaki, T; Miyamoto, A; Hirayanagi, K

    2000-01-01

    A measure to counteract the effects of low or zero gravity is required for long-term space flight, such as the manned Mars mission scheduled by the National Aeronautics and Space administration (NASA) for 2014. We conducted a series of centrifugation experiments with humans, using a short-arm centrifuge (radius 1.8 m, made by First Medical Co., Tokyo, Japan). We employed 6-degree, head-down tilt (HDT) for 4 days to simulate space flight. Ten healthy male volunteers underwent 4-day HDT and a 2-G daily centrifuge load for 60 min in the +Gz direction and measurements, such as haematocrit, 24-h urine volume, body weight and electrocardiogram (ECG) were made. There was no significant increase in the haematocrit during the HDT period, although our previous studies had shown a significant increase during HDT. A 60-min daily load of +2 Gz appears to be effective in reversing the haematocrit increase due to 4-day HDT. PMID:11200989

  18. Caloric restriction decreases orthostatic tolerance independently from 6° head-down bedrest.

    PubMed

    Florian, John P; Baisch, Friedhelm J; Heer, Martina; Pawelczyk, James A

    2015-01-01

    Astronauts consume fewer calories during spaceflight and return to earth with an increased risk of orthostatic intolerance. Whether a caloric deficiency modifies orthostatic responses is not understood. Thus, we determined the effects of a hypocaloric diet (25% caloric restriction) during 6° head down bedrest (an analog of spaceflight) on autonomic neural control during lower body negative pressure (LBNP). Nine healthy young men completed a randomized crossover bedrest study, consisting of four (2 weeks each) interventions (normocaloric bedrest, normocaloric ambulatory, hypocaloric bedrest, hypocaloric ambulatory), each separated by 5 months. Muscle sympathetic nerve activity (MSNA) was recorded at baseline following normocaloric and hypocaloric interventions. Heart rate (HR) and arterial pressure were recorded before, during, and after 3 consecutive stages (7 min each) of LBNP (-15, -30, -45 mmHg). Caloric and posture effects during LBNP were compared using two-way ANOVA with repeated measures. There was a strong trend toward reduced basal MSNA following caloric restriction alone (normcaloric vs. hypocaloric: 22±3 vs. 14±4 burst/min, p = 0.06). Compared to the normocaloric ambulatory, both bedrest and caloric restriction were associated with lower systolic blood pressure during LBNP (p<0.01); however, HR responses were directionally opposite (i.e., increase with bedrest, decrease with caloric restriction). Survival analysis revealed a significant reduction in orthostatic tolerance following caloric restriction (normocaloric finishers: 12/16; hypocaloric finishers: 6/16; χ2, p = 0.03). Caloric restriction modifies autonomic responses to LBNP, which may decrease orthostatic tolerance after spaceflight. PMID:25915488

  19. Caloric Restriction Decreases Orthostatic Tolerance Independently from 6° Head-Down Bedrest

    PubMed Central

    Florian, John P.; Baisch, Friedhelm J.; Heer, Martina; Pawelczyk, James A.

    2015-01-01

    Astronauts consume fewer calories during spaceflight and return to earth with an increased risk of orthostatic intolerance. Whether a caloric deficiency modifies orthostatic responses is not understood. Thus, we determined the effects of a hypocaloric diet (25% caloric restriction) during 6° head down bedrest (an analog of spaceflight) on autonomic neural control during lower body negative pressure (LBNP). Nine healthy young men completed a randomized crossover bedrest study, consisting of four (2 weeks each) interventions (normocaloric bedrest, normocaloric ambulatory, hypocaloric bedrest, hypocaloric ambulatory), each separated by 5 months. Muscle sympathetic nerve activity (MSNA) was recorded at baseline following normocaloric and hypocaloric interventions. Heart rate (HR) and arterial pressure were recorded before, during, and after 3 consecutive stages (7 min each) of LBNP (-15, -30, -45 mmHg). Caloric and posture effects during LBNP were compared using two-way ANOVA with repeated measures. There was a strong trend toward reduced basal MSNA following caloric restriction alone (normcaloric vs. hypocaloric: 22±3 vs. 14±4 burst/min, p = 0.06). Compared to the normocaloric ambulatory, both bedrest and caloric restriction were associated with lower systolic blood pressure during LBNP (p<0.01); however, HR responses were directionally opposite (i.e., increase with bedrest, decrease with caloric restriction). Survival analysis revealed a significant reduction in orthostatic tolerance following caloric restriction (normocaloric finishers: 12/16; hypocaloric finishers: 6/16; χ2, p = 0.03). Caloric restriction modifies autonomic responses to LBNP, which may decrease orthostatic tolerance after spaceflight. PMID:25915488

  20. Hoffmann-reflex is delayed during 6 degree head-down tilt with balanced traction

    NASA Technical Reports Server (NTRS)

    Haruna, Y.; Styf, J. R.; Kahan, N.; Hargens, A. R.

    1999-01-01

    BACKGROUND: Increased spinal height due to the lack of of axial compression on spinal structures in microgravity may stretch the spinal cord, cauda equina, nerve roots, and paraspinal tissues. HYPOTHESIS: Exposure to simulated microgravity causes dysfunction of nerve roots so that the synaptic portion of the Achilles tendon reflex is delayed. METHODS: Six healthy male subjects were randomly divided into two groups with three in each group. The subjects in the first group underwent horizontal bed rest (HBR) for three days. After a two week interval they underwent bed rest in a position of head-down tilt with balanced traction (HDT). So that each subject could serve as his own control, the second group was treated identically but in opposite order. Bilateral F waves and H-reflexes were measured daily (18:30-20:30) on all subjects placed in a prone position. RESULTS: By means of ANOVA, differences between HDT and HBR were observed only in M-latency and F-ratio, not in F-latency, central latency, and H-latency. Differences during the course of the bed rest were observed in M-latency and H-latency only. Tibial H latency was significantly lengthened in HDT group on day 2 and 3, although no significant difference between HDT and HBR was observed. CONCLUSION: The monosynaptic reflex assessed by H-reflex was delayed during 6 degree HDT with traction. The exact mechanism of this delay and whether the change was due to lengthening of the lower part of the vertebrae remain to be clarified.

  1. Back pain during 6 degrees head-down tilt approximates that during actual microgravity

    NASA Technical Reports Server (NTRS)

    Hutchinson, K. J.; Watenpaugh, D. E.; Murthy, G.; Convertino, V. A.; Hargens, A. R.

    1995-01-01

    Astronauts often experience back pain during spaceflight. Retrospectively, Wing et al. (14) found that during spaceflight, 14 of 19 Shuttle crewmembers experienced back pain, which they described as dull (62%), localized to the lower back (50%), and with an intensity of 2 on a 5-point scale. Further, the spine lengthens 4-7 cm in microgravity. Our objective was to compare back pain and spinal lengthening (body height increase) during simulated microgravity (6 degrees head-down tilt, HDT) with the same parameters during actual microgravity. Eight male subjects completed a modified McGill pain questionnaire with intensity graded from zero (no pain) to five (intense and incapacitating pain) each day at 7:00 pm during 2 d pre-HDT control, 16 d HDT, and 1 d post-HDT recovery periods. Also, the subjects' heights were measured each day while supine (control and recovery) and during HDT. Back pain increased from zero (pre-tilt control period) to 2.3 +/- 0.4 at days 1 to 3 of HDT, and was categorized as dull and/or burning pain in subjects' lower backs. Only 2 subjects reported any pain after day 9 of HDT and during recovery. Heights increased 2.1 +/- 0.5 cm by day 3 of HDT and remained at that level until the end of the HDT period. Although spinal lengthening in space is greater than that during HDT, the HDT model approximates the level, type, distribution, and time course of back pain associated with actual microgravity. In the HDT model, pain subsides in intensity when spinal lengthening stops.(ABSTRACT TRUNCATED AT 250 WORDS).

  2. Leg venous hemodynamics and leg volumes during a 42-day-6 ° head-down bedrest

    NASA Astrophysics Data System (ADS)

    Louisy, F.; Schroiff, P.; Guezennec, C.-Y.; Güell, A.

    Seven healthy subjects were submitted to a 42-day head down bedrest, where leg venous compliance (venous distensibity index VDI) and leg volumes were assessed by mercury strain gauge plethysmography with venous occlusion and optoelectronic plethysmography, respectively. Plethysmographic and volometric measurements were made, before, during (at days 1, 4, 7, 14, 21, 26, 34 and 41), and after bedrest (days 1, 4, 7, 11 and 30 of the recovery period). Results showed a continuous decrease in leg volumes throughout bedrest, when VDI increased until day 26 of bedrest, and then decreased afterwards. The recovery period was characterized by a rapid return of VDI to prebedrest levels while leg volumes progressively normalised. These results showed that leg venous compliance changes are not always dependant upon skeletal muscle changes, and that factors other than size of muscle compartment are able to determine increases in leg venous compliance during long-term bedrest.

  3. Clinical effects of thigh cuffs during a 7-day 6° head-down bed rest

    NASA Astrophysics Data System (ADS)

    Pavy-Le Traon, Anne; Maillet, Alain; Vasseur Clausen, Pascale; Custaud, Marc-Antoine; Alferova, Irina; Gharib, Claude; Fortrat, Jacques-Olivier

    2001-08-01

    Thigh cuffs are used by Russian cosmonauts to limit the fluid shift induced by space flight. A ground simulation using the head-down bed rest (HDBR) model was performed to assess the effects of thigh cuffs on clinical tolerance and orthostatic adaptation. 8 male healthy volunteers (32.4±1.9 years) participated twice in a 7-day HDBR — one time with thigh cuffs (worm daily from 9 am to 7 pm) (TC) and one time without (WTC). Orthostatic tolerance was assessed by a 10 minute stand test and by a LBNP test (5 min at -15, -30, -45 mmHg) before (BDC-1) and at the end of the HDBR period (R+1). Plasma volume was measured before and at the end of HDBR by the Evans blue dye dilution technique. Thigh cuffs limits headache due to fluid shift, as well as the loss in plasma volume (TC: -5.85±0.95%; WTC: -9.09±0.82%, p<0.05). The mean duration of the stand test (R+1) did not differ in the two group (TC 7.1±1.3 min; WTC 7.0±1.0 min). The increase in HR and decrease in diastolic blood pressure were slightly but significantly larger without thigh cuffs. Duration of the LBNP tests did not differ with thigh cuffs. Thigh cuffs limit the symptoms due to fluid shift and the loss in plasma volume. They partly reduced the increase in HR during orthostatic stress but had no effect on duration of orthostatic stress tests.

  4. Sex differences in blood pressure control during 6° head-down tilt bed rest

    PubMed Central

    Arzeno, Natalia M.; Lee, Stuart M. C.; Ploutz-Snyder, Robert; Platts, Steven H.

    2013-01-01

    Spaceflight-induced orthostatic intolerance has been studied for decades. Although ∼22% of the astronaut corps are women, most mechanistic studies use mostly male subjects, despite known sex differences in autonomic control and postflight orthostatic intolerance. We studied adrenergic, baroreflex, and autonomic indexes during continuous infusions of vasoactive drugs in men and women during a 60-day head-down bed rest. Volunteers were tested before bed rest (20 men and 10 women) and around day 30 (20 men and 10 women) and day 60 (16 men and 8 women) of bed rest. Three increasing doses of phenylephrine (PE) and sodium nitroprusside were infused for 10 min after an infusion of normal saline. A 20-min rest period separated the phenylephrine and sodium nitroprusside infusions. Autonomic activity was approximated by spectral indexes of heart rate and blood pressure variability, and baroreflex sensitivity was measured by the spontaneous baroreflex slope. Parasympathetic modulation and baroreflex sensitivity decreased with bed rest, with women experiencing a larger decrease in baroreflex sensitivity by day 30 than men. The sympathetic activation of men and parasympathetic responsiveness of women in blood pressure control during physiological stress were preserved throughout bed rest. During PE infusions, women experienced saturation of the R-R interval at high frequency, whereas men did not, revealing a sex difference in the parabolic relationship between high-frequency R-R interval, a measurement of respiratory sinus arrhythmia, and R-R interval. These sex differences in blood pressure control during simulated microgravity reveal the need to study sex differences in long-duration spaceflight to ensure the health and safety of the entire astronaut corps. PMID:23396455

  5. Isokinetic and isometric strength-endurance after 6 hours of immersion and 6 degrees head-down tilt in men

    NASA Technical Reports Server (NTRS)

    Shaffer-Bailey, M.; Greenleaf, J. E.; Hutchinson, T. M.

    1996-01-01

    PURPOSE: To determine weight (water) loss levels for onset of muscular strength and endurance changes during deconditioning. METHODS: Seven men (27-40 yr) performed maximal shoulder-, knee-, and ankle-joint isometric (0 degree.s(-1) load) and isokinetic (60 degrees, 120 degrees, 180 degrees.s(-1) velocity) exercise tests during ambulatory control (AC), after 6 h of 6 degrees head-down tilt (HDT; dry-bulb temp. = 23.2 +/- SD 0.6 degrees C, relative humidity = 31.1+/- 11.1%) and after 6 h of 80 degrees foot-down head-out water immersion (WI; water temp. = 35.0 +/- SD 0.1 degree C) treatments. RESULTS: Weight (water) loss after HDT (1.10 +/- SE 0.14 kg, 1.4 +/- 0.2% body wt) and WI (1.54+/- 0.19 kg, 2.0 +/- 0.2% body wt) were not different, but urinary excretion with WI (1,354 +/- 142 ml.6 h(-1)) was 28% greater (p < 0.05) than that of 975 +/- 139 ml.6 h(-1) with HDT. Muscular endurance (total work; maximal flexion-extension of the non-dominant knee at 180 degrees.s(-1) for 30 s) was not different between AC and the WI or HDT treatments. Shoulder-, knee-, and ankle-joint strength was unchanged except for three knee-joint peak torques: AC torque (120 degrees.s(-1), 285 +/- 20 Nm) decreased to 268 +/- 21 Nm (delta = -6%, p < 0.05) with WI; and AC torques (180 degrees.s(-1), 260 +/- 19 Nm) decreased to 236 +/- 15 Nm (delta = -9%, p < 0.01) with HDT, and to 235 +/- 19 Nm (delta = -10%, p < 0.01) with WI. CONCLUSION: Thus, the total body hypohydration threshold level for shoulder- and ankle-joint strength and endurance decrements is more than 2% body weight (water) loss, while significant reduction in knee-joint muscular strength-endurance occurred only at moderate (120 degrees.s(-1) and lighter (180 degrees.s(-1)) loads with body weight loss of 1.4-2.0% following WI or HDT, respectively. These weight (water) losses and knee-joint strength decrements are somewhat less than the mean weight loss of 2.6% and knee-joint strength decrements of 6-20% of American astronauts after

  6. Effects of 45-day -6° head-down bed rest on the time-based prospective memory

    NASA Astrophysics Data System (ADS)

    Chen, SiYi; Zhou, RenLai; Xiu, LiChao; Chen, ShanGuang; Chen, XiaoPing; Tan, Cheng

    2013-03-01

    The research explored the effects of 45-day -6° head-down bed rest (HDBR) simulation of microgravity on the time-based prospective memory (PM) with 16 males. The time-based prospective memory task was performed on the 2nd day before HDBR, on the 11th, 20th, 32nd, and 40th days during HDBR, and on the 8th day after HDBR, and subjects' anxiety and depression feelings were recorded simultaneously using Beck Anxiety Inventory (BAI) and Beck Depression Inventory (BDI). The results demonstrated that it showed decreased accuracy of PM responses and frequency of clock checks during and after bed rest; long term bed rest did not induce significant emotional changes. The deficit of prospective memory performance induced by long term HDBR may result from a lack of aerobic physical activity or changes in the prefrontal cortex, but it remains to be determined.

  7. Leg muscle volume during 30-day 6-degree head-down bed rest with isotonic and isokinetic exercise training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Lee, P. L.; Ellis, S.; Selzer, R. H.; Ortendahl, D. A.

    1994-01-01

    Magnetic resonance imaging (MRI) was used to compare the effect of two modes of lower-extremity exercise training on the mass (volume) of posterior leg group (PLG) muscles (soleus, flexor hallucis longus, tibialis posterior, lateral and medial gastrocnemius, and flexor digitorum longus) on 19 men (ages 32-42 years) subjected to intense dynamic-isotonic (ITE, cycle ergometer, number of subjects (N) = 7), isokinetic (IKE, torque egrometer, N = 7), and no exercise (NOE, N = 5) training for 60 min/day during head-down bed rest (HDBR). Total volume of the PLG muscles decreased (p less than 0.05) similarly: ITE = 4.3 +/- SE 1.6%, IKE = 7.7 +/- 1.6%, and NOE = 6.3 +/- 0.8%; combined volume (N = 19) loss was 6.1 +/- 0.9%. Ranges of volume changes were 2.6% to -9.0% (ITE), -2.1% to -14.9% (IKE), and -3.4% to -8/1% (NOE). Correlation coefficients (r) of muscle volume versus thickness measured with ultrasonography were: ITE r + 0.79 (p less than 0.05), IKE r = 0.27 (not significant (NS)), and NOE r = 0.63 (NS). Leg-muscle volume and thickness were highly correlated (r = 0.79) when plasma volume was maintained during HDBR with ITE. Thus, neither intensive lower extremity ITE nor IKE training influence the normal non-exercised posterior leg muscle atrophy during HDBR. The relationship of muscle volume and thickness may depend on the mode of exercise training associated with the maintenance of plasma volume.

  8. Gender differences in endocrine responses to posture and 7 days of -6 degrees head-down bed rest

    NASA Technical Reports Server (NTRS)

    Vernikos, J.; Dallman, M. F.; Keil, L. C.; O'Hara, D.; Convertino, V. A.

    1993-01-01

    Endocrine regulation of fluids and electrolytes during 7 days of -6 degrees head-down bed rest (HDBR) was compared in male (n = 8) and, for the first time, female (n = 8) volunteers. The subjects' responses to quiet standing for 2 h before and after HDBR were also tested. In both sexes, diuresis and natriuresis were evident during the first 2-3 days of HDBR, resulting in a marked increase in the urinary Na(+)-to-K+ ratio and significant Na+ retention on re-ambulation. After the 1st day of HDBR, plasma renin activity (PRA) was increased relative to aldosterone (Aldo), plasma volume was decreased, and the renal response to Aldo appeared to be appropriate. Circulating levels of arginine vasopressin, cortisol, and ACTH were unchanged during HDBR. Plasma testosterone decreased slightly on day 2 of HDBR in males. The ratio of early morning ACTH to cortisol was lower in females than in males because ACTH was lower in females. Urinary cortisol increased and remained elevated throughout the HDBR in males only. There were no gender differences in the responses to 7 days of HDBR, except those in the pituitary-adrenal system; those differences appeared unrelated to the postural change. The provocative cardiovascular test of quiet standing before and after HDBR revealed both sex differences and effects of HDBR. There were significant sex differences in cardiovascular responses to standing before and after HDBR. Females had greater PRA and Aldo responses to standing before HDBR and larger Aldo responses to standing after HDBR than males.(ABSTRACT TRUNCATED AT 250 WORDS).

  9. Cognitive Functioning in Long Duration Head-down Bed Rest

    NASA Technical Reports Server (NTRS)

    Seaton, Kimberly A.; Slack, Kelley J.; Sipes, Walter A.; Bowie, Kendra

    2008-01-01

    The Space Flight Cognitive Assessment Tool for Windows (WinSCAT) is a self-administered battery of tests used on the International Space Station for evaluating cognitive functioning. Here, WinSCAT was used to assess cognitive functioning during extended head-down bed rest. Thirteen subjects who participated in 60 or 90 days of 6 deg head-down bed rest took WinSCAT during the pre-bed rest phase, the in-bed rest phase, and the post-bed rest (reconditioning) phase of study participation. After adjusting for individual baseline performance, 12 off-nominal scores were observed out of 351 total observations during bed rest and 7 of 180 during reconditioning. No evidence was found for systematic changes in off-nominal incidence as time in bed rest progressed, or during the reconditioning period. Cognitive functioning does not appear to be adversely affected by long duration head-down bed rest. Individual differences in underlying cognitive ability and motivation level are likely explanations for the current findings.

  10. Measurement of Transcranial Distance During Head-Down Tilt Using Ultrasound

    NASA Technical Reports Server (NTRS)

    Torikoshi, Shigeyo; Ballard, R. E.; Watenpaugh, D. E.; Murthy, G.; Bowley, S.; Yost, W. T.; Hargens, Alan R.

    1995-01-01

    Exposure to microgravity probably elevates blood pressure and flow in the head which may increase intracranial volume (ICV) and pressure (ICP). Due to the slightly compliant nature of the cranium, any increase of ICP will increase ICV and transcranial distance. We used a noninvasive ultrasound technique to measure transcranial distance (frontal to occipital) during head-down tilt. Seven subjects (ages 26-53) underwent the following tilt angles: 90 deg. upright, 30 deg., 0 deg., -6 deg., -10 deg., -6 deg., 0 deg., 30 deg., and 90 deg. Each angle was maintained for 1 min. Ultrasound wave frequency was collected continuously and transcranial distance was calculated (Delta(x) = x(Delta)f/f, where x is path length and f is frequency of the wave) for each tilt angle. Frequency decreased from 503.687 kHz (90 deg. upright) to 502.619 kHz (-10 deg.). These frequencies translated to an increased transcranial distance of 0.403 mm. Although our data suggest a significant increase in transcranial distance during head-down tilt, this apparent increase may result, in part, from head-down tilt-induced subcutaneous edema or cutaneous blood volume elevation. In three subjects, when the above protocol was repeated with an ace bandage wrapped around the head to minimize such edema, the increased transcranial distance from 90 deg. to -10 deg. was reduced by 0.174 mm. Further development of the technique to quantify bone-to-bone expansion unconfounded by cutaneous fluid is necessary. Therefore, this ultrasound technique may provide measurements of changes in cranial dimensions during microgravity.

  11. Performance and mood-state parameters during 30-day 6 deg head-down bed rest with exercise training

    NASA Technical Reports Server (NTRS)

    Deroshia, Charles W.; Greenleaf, J. E.

    1993-01-01

    A study aimed at determining if the performance and mood impairments occur in bed-rested subjects, and if different exercise-training regimens modify or prevent them is presented. Eighteen healthy men were divided into three groups performing no exercise, isotonic exercise, and isokinetic exercise. Few deleterious changes occurred in performance and mood of the three groups which did not exceed baseline ambulatory levels. It is concluded that mood and performance did not deteriorate in response to prolonged bedrest and were not altered by exercise training.

  12. Isokinetic Strength and Endurance During 30-day 6 deg Head-Down Bed Rest with Isotonic and Isokinetic Exercise Training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Bernauer, E. M.; Ertl, A. C.; Bond, M.; Bulbulian, R.

    1994-01-01

    The purpose of our study was to determine if an intensive, intermittent, isokinetic, lower extremity exercise training program would attenuate or eliminate the decrease of muscular strength and endurance during prolonged bed rest (BR). The 19 male subjects (36 +/- 1 yr, 178 +/- 2 cm, 76.5 +/- 1.7 kg) were allocated into a no exercise (NOE) training group (N = 5), an isotonic (lower extremity cycle orgometer) exercise (ITE) training group (N = 7), and an isokinetic (isokinetic knee flexion-extension) exercise (IKE) training group (N = 7). Peak knee (flexion and extension) and shoulder (abduction-adduction) functions were measured weekly in all groups with one 5-repetition set. After BR, average knee extension total work decreased by 16% with NOE, increased by 27% with IKE, and was unchanged with ITE. Average knee flexion total work and peak torque (strength) responses were unchanged in all groups. Force production increased by 20% with IKE and was unchanged with NOE and ITE. Shoulder total work was unchanged in all groups, while gross average peak torque increased by 27% with ITE and by 22% with IKE, and was unchanged with NOE. Thus, while ITE training can maintain some isokinetic functions during BR, maximal intermittent IKE training can increase other functions above pre-BR control levels.

  13. Exercise thermoregulation after 6 h of chair rest, 6 degrees head-down bed-rest, and water immersion deconditioning in men

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Hutchinson, T.; Shaffer-Bailey, M.; Looft-Wilson, R.

    1996-01-01

    The purpose was to investigate the mechanism for the excessive exercise hyperthermia following deconditioning (reduction of physical fitness). Rectal (Tre) and mean skin (Tsk) temperatures and thermoregulatory responses were measured in six men [mean (SD) age, 32 (6) years; mass, 78.26 (5.80) kg; surface area, 1.95 (0.11) m2; maximum oxygen uptake (VO2max), 48 (6) ml.min-1.kg-1; whilst supine in air at dry bulb temperature 23.2 (0.6) degree C, relative humidity 31.1 (11.1)% and air speed 5.6 (0.1) m.min-1] during 70 min of leg cycle exercise [51 (4)% VO2max] in ambulatory control (AC), or following 6 h of chair rest (CR), 6 degree head-down bed rest (BR), and 20 degree (WI20) and 80 degree (WI80) foot-down water immersion [water temperature, 35.0 (0.1) degree C]. Compared with the AC exercise delta Tre [mean (SD) 0.77 (0.13) degree C (*P < 0.05), after WI80 0.96 (0.13) degree C*, and after WI20 1.03 (0.09) degree C*. All Tsk responded similarly to exercise: they decreased (NS) by 0.5-0.7 degree C in minutes 4-8 and equilibrated at +0.1 to +0.5 degree C at 60-70. Skin heat conductance was not different among the five conditions (range = 147-159 kJ.m-2.h-1.degree C-1). Results from an intercorrelation matrix suggested that total body sweat rate was more closely related to Tre at 70 min (Tre70) than limb sweat rate or blood flow. Only 36% of the variability in Tre70 could be accounted for by total sweating, and less than 10% from total body dehydration. It would appear that multiple factors are involved which may include change in sensitivity of thermo- and osmoreceptors.

  14. Knee-joint proprioception during 30-day 6 degrees head-down bed rest with isotonic and isokinetic exercise training

    NASA Technical Reports Server (NTRS)

    Bernauer, E. M.; Walby, W. F.; Ertl, A. C.; Dempster, P. T.; Bond, M.; Greenleaf, J. E.

    1994-01-01

    To determine if daily isotonic exercise or isokinetic exercise training coupled with daily leg proprioceptive training, would influence leg proprioceptive tracking responses during bed rest (BR), 19 men (36 +/- SD 4 years, 178 +/- 7 cm, 76.8 +/- 7.8 kg) were allocated into a no-exercise (NOE) training control group (n = 5), and isotonic exercise (ITE, n = 7) and isokinetic exercise (IKE, n = 7) training groups. Exercise training was conducted during BR for two 30-min periods.d-1, 5 d.week-1. Only the IKE group performed proprioceptive training using a new isokinetic procedure with each lower extremity for 2.5 min before and after the daily exercise training sessions; proprioceptive testing occurred weekly for all groups. There were no significant differences in proprioceptive tracking scores, expressed as a percentage of the perfect score of 100, in the pre-BR ambulatory control period between the three groups. Knee extension and flexion tracking responses were unchanged with NOE during BR, but were significantly greater (*p < 0.05) at the end of BR in both exercise groups when compared with NOE responses (extension: NOE 80.7 +/- 0.7%, ITE 82.9* +/- 0.6%, IKE 86.5* +/- 0.7%; flexion: NOE 77.6 +/- 1.5%, ITE 80.0 +/- 0.8% (NS), IKE 83.6* +/- 0.8%). Although proprioceptive tracking was unchanged during BR with NOE, both isotonic exercise training (without additional proprioceptive training) and especially isokinetic exercise training when combined with daily proprioceptive training, significantly improved knee proprioceptive tracking responses after 30 d of BR.

  15. Effect of leg exercise training on vascular volumes during 30 days of 6 degrees head-down bed rest

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Vernikos, J.; Wade, C. E.; Barnes, P. R.

    1992-01-01

    Plasma and red cell volumes, body density, and water balance were measured in 19 men (32-42 yr) confined to bed rest (BR). One group (n = 5) had no exercise training (NOE), another near-maximal variable-intensity isotonic exercise for 60 min/day (ITE; n = 7), and the third near-maximal intermittent isokinetic exercise for 60 min/day (IKE; n = 7). Caloric intake was 2,678-2,840 kcal/day; mean body weight (n = 19) decreased by 0.58 +/- 0.35 (SE) kg during BR due to a negative fluid balance (diuresis) on day 1. Mean energy costs for the NOE, and IKE, and ITE regimens were 83 (3.6 +/- 0.2 ml O2.min-1.kg-1), 214 (8.9 +/- 0.5 ml.min-1.kg-1), and 446 kcal/h (18.8 +/- 1.6 ml.min-1.kg-1), respectively. Body densities within groups and mean urine volumes (1,752-1,846 ml/day) between groups were unchanged during BR. Resting changes in plasma volume (ml/kg) after BR were -1.5 +/- 2.3% (NS) in ITE, -14.7 +/- 2.8% (P less than 0.05) in NOE, and -16.8 +/- 2.9% (P less than 0.05) in IKE, and mean water balances during BR were +295, -106, and +169 ml/24 h, respectively. Changes in red cell volume followed changes in plasma volume. The significant chronic decreases in plasma volume in the IKE and NOE groups and its maintenance in the ITE group could not be accounted for by water balance or by responses of the plasma osmotic, protein, vasopressin, or aldosterone concentrations or plasma renin activity. There was close coupling between resting plasma volume and plasma protein and osmotic content.(ABSTRACT TRUNCATED AT 250 WORDS).

  16. Lower Extremity Muscle Thickness During 30-Day 6 degrees Head-Down Bed Rest with Isotonic and Isokinetic Exercise Training

    NASA Technical Reports Server (NTRS)

    Ellis, S.; Kirby, L. C.; Greenleaf, J. E.

    1993-01-01

    Muscle thickness was measured in 19 Bed-Rested (BR) men (32-42 year) subjected to IsoTonic (ITE, cycle orgometer) and IsoKi- netic (IKE, torque orgometer) lower extremity exercise training, and NO Exercise (NOE) training. Thickness was measured with ultrasonography in anterior thigh-Rectus Femoris (RF) and Vastus Intermadius (VI), and combined posterior log-soleus, flexor ballucis longus, and tibialis posterior (S + FHL +TP) - muscles. Compared with ambulatory control values, thickness of the (S + FHL + TP) decreased by 90%-12% (p less than 0.05) In all three test groups. The (RF) thickness was unchanged in the two exercise groups, but decreased by 10% (p less than 0.05) in the NOE. The (VI) thickness was unchanged In the ITE group, but decreased by 12%-l6% (p less than 0.05) in the IKE and NOE groups. Thus, intensive, alternating, isotonic cycle ergometer exercise training is as effective as intensive, intermittent, isokinetic exercise training for maintaining thicknesses of rectus femoris and vastus lntermedius anterior thigh muscles, but not posterior log muscles, during prolonged BR deconditioning.

  17. Head-down bed rest impairs vagal baroreflex responses and provokes orthostatic hypotension

    NASA Technical Reports Server (NTRS)

    Convertino, Victor A.; Doerr, Donald F.; Eckberg, Dwain L.; Fritsch, Janice M.; Vernikos-Danellis, Joan

    1990-01-01

    The hypothesis that baroreflex malfunction contributes to orthostatic hypotension in microgravity was tested by studying vagally mediated carotid baroreceptor-cardiac reflexes in healthy human subjects before, during, and after 30 days of 6-deg head-down bed rest. The baroreflex response relationships were provoked with ramped neck pressure-suction sequences comprising pressure elevations to 40 mm Hg followed by serial R-wave-triggered 15-mm Hg reductions to -65 mm0 Hg; each R-R interval was plotted as a function of systolic pressure minus the neck chamber pressure applied during the interval. It is shown that head-down bed rest led to an impairment of vagal baroreflex function and that it was associated with an impairment of hemodynamic adjustments to standing, indicating that baroreflex impairment may contribute to orthostatic hypotension observed in spacecrews after a flight.

  18. Submaximal Exercise VO2 and Q During 30-Day 6 degree Head-Down Bed Rest with Isotonic and Isokinetic Exercise Training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Bernauer, E. M.; Erti, A. C.

    1995-01-01

    Submaximal exercise (61+3% peak VO2) metabolism was measured before (AC day-2) and on bed rest day 4, 11, and 25 in 19 healthy men (32-42 yr) allocated into no exercise (NOE, N=5) control, and isotonic exercise (ITE, N=7)and isokinetic exercise (IKE, N=7) training groups. Training was conducting supine for two 30-min periods/d for 6 d/wk: ITE was 60-90% peak VO2: IKE was peak knee flexion-extension at 100 deg/s. Supine submaximal exercise 102 decreased significantly (*p<0.05) by 10.3%, with ITE and by 7.3%* with IKE; similar to the submaximal cardiac output (Q) change of -14.5%* (ITE) and -203%* (IKE), but different from change in peak VO2 (+1.4% with ITE and - 10.2%, with IKE) and plasma volume of -3.7% (ITE) and - 18.0% * (IKE). Thus, reduction of submaximal V02 during prolonged bed rest appears to respond to submaximal Q but is not related to change in peak VO2 or plasma volume.

  19. Cerebrospinal fluid pressure in conscious head-down tilted rats

    NASA Technical Reports Server (NTRS)

    Severs, Walter B.; Morrow, Bret A.; Keil, Lanny C.

    1991-01-01

    The acute effects of a 1-h -45 deg head-down tilt on continouously recorded cerebrospinal fluid pressure (PCSF) of conscious rats are studied in order to investigate the shift of blood volume into the thoracic cavity in microgravity. PCSF, evaluated in 15-min time blocks over a 3-h experiment, increased slightly (less than 0.05) during the first 30 min of a control hour at 0 deg. There was a transient increase for about 5 min immediately after tilt (-45 deg) that may have been due to head movement after the position change. PCSF was statistically unchanged (above 0.05) during the second (-45 deg) hour and the third (0 deg) recovery hour. It is shown that the dynamics of intracranial pressure regulation can accommodate the acute cephalad fluid shift after tilting.

  20. Cerebral blood velocity and other cardiovascular responses to 2 days of head-down tilt

    NASA Technical Reports Server (NTRS)

    Frey, Mary A. B.; Mader, Thomas H.; Bagian, James P.; Charles, John B.; Meehan, Richard T.

    1993-01-01

    Spaceflight induces a cephalad redistribution of fluid volume and blood flow within the human body, and space motion sickness, which is a problem during the first few days of space flight, could be related to these changes in fluid status and in blood flow of the cerebrum and vestibular system. To evaluate possible changes in cerebral blood flow during simulated weightlessness, we measured blood velocity in the middle cerebral artery (MCA) along with retinal vascular diameters, intraocular pressure, impedance cardiography, and sphygmomanometry on nine men (26.2 +/- 6.6 yr) morning and evening for 2 days during continuous 10 deg head-down tilt (HDT). When subjects went from seated to head-down bed rest, their heart rate and retinal diameters decreased, and intraocular pressures increased. After 48 h of HDT, blood flow velocity in the MCA was decreased and thoracic impedance was increased, indicating less fluid in the thorax. Percent changes in blood flow velocities in the MCA after 48 h of HDT were inversely correlated with percent changes in retinal vascular diameters. Blood flow velocities in the MCA were inversely correlated (intersubject) with arterial pressures and retinal vascular diameters. Heart rate, stroke volume, cardiac output, systolic arterial pressure, and at times pulse pressure and blood flow velocities in the MCA were greater in the evening. Total peripheral resistance was higher in the morning. Although cerebral blood velocity is reduced after subjects are head down for 2 days, the inverse relationship with retinal vessel diameters, which have control analogous to that of cerebral vessels, indicates cerebral blood flow is not reduced.

  1. Effects of 10 days 6 degrees head-down tilt on the responses to fluid loading and lower body negative pressure

    NASA Technical Reports Server (NTRS)

    Baisch, F.; Heer, M.; Beck, L.; Blomqvist, C. G.; Kropp, J.; Schulz, H.; Hillebrecht, A.; Meyer, M.

    1991-01-01

    In an international collaborative project six normal male subjects were studied before, during and after 10 days 6 degrees HDT. Fluid intake was controlled at 40 ml/(kgbw day). Urine volume and body weight were determined daily. Fluid loading and LBNP were performed in all three phases of the study. Body weight diminished by 2.6% because of fluid loss. Blood volume diminished by 13%. The responses to fluid loading were similar in the three phases of the study. Sixty minutes after end of infusion only 5.5% of the infused saline remained in the intravascular compartment. Excess interstitial fluid was eliminated in the next 24 hs but a negative balance was recorded also in the following day. The compliance of the lower limbs expressed as the rate of limb volume change/unit LBNP change was increased at the end of the HDT phase and during the post HDT phase. The set point of intravascular volume was defended, as shown by the response to FL. HDT increased the compliance of the lower limbs.

  2. Effects of 10 days 6° head-down tilt on the responses to fluid loading and lower body negative pressure

    NASA Astrophysics Data System (ADS)

    Baisch, F.; Heer, M.; Beck, L.; Blomqvist, C. G.; Kropp, J.; Schulz, H.; Hillebrecht, A.; Meyer, M.

    In an international collaborative project six normal male subjects were studied before, during and after 10 days 6° HDT. Fluid intake was controlled at 40 ml/(kg bw·day). Urine volume and body weight were determined daily. Fluid loading and LBNP were performed in all three phases of the study. Body weight diminished by 2.6% because of fluid loss. Blood volume diminished by 13%. The responses to fluid loading were similar in the three phases of the study. Sixty minutes after end of infusion only 5.5% of the infused saline remained in the intravascular compartment. Excess interstitial fluid was eliminated in the next 24 hs but a negative balance was recorded also in the following day. The compliance of the lower limbs expressed as the rate of limb volume change/unit LBNP change was increased at the end of the HDT phase and during the post HDT phase. The set point of intravascular volume was defended, as shown by the response to FL. HDT increased the compliance of the lower limbs.

  3. Submaximal exercise VO2 and Qc during 30-day 6 degrees head-down bed rest with isotonic and isokinetic exercise training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Ertl, A. C.; Bernauer, E. M.

    1996-01-01

    BACKGROUND: Maintaining intermediary metabolism is necessary for the health and well-being of astronauts on long-duration spaceflights. While peak oxygen uptake (VO2) is consistently decreased during prolonged bed rest, submaximal VO2 is either unchanged or decreased. METHODS: Submaximal exercise metabolism (61 +/- 3% peak VO2) was measured during ambulation (AMB day-2) and on bed rest days 4, 11, and 25 in 19 healthy men (32-42 yr) allocated into no exercise (NOE, N = 5) control, and isotonic exercise (ITE, N = 7) and isokinetic exercise (IKE, N = 7) training groups. Exercise training was conducted supine for two 30-min periods per day for 6 d per week: ITE training was intermittent at 60-90% peak VO2; IKE training was 10 sets of 5 repetitions of peak knee flexion-extension force at a velocity of 100 degrees s-1. Cardiac output was measured with the indirect Fick CO2 method, and plasma volume with Evans blue dye dilution. RESULTS: Supine submaximal exercise VO2 decreased significantly (*p < 0.05) by 10.3%* with ITE and by 7.3%* with IKE; similar to the submaximal cardiac output decrease of 14.5%* (ITE) and 20.3%* (IKE), but different from change in peak VO2 (+1.4% with ITE and -10.2%* with IKE) and decrease in plasma volume of -3.7% (ITE) and -18.0%* (IKE). Reduction of submaximal VO2 during bed rest correlated 0.79 (p < 0.01) with submaximal Qc, but was not related to change in peak VO2 or plasma volume. CONCLUSION: Reduction in submaximal oxygen uptake during prolonged bed rest is related to decrease in exercise but not resting cardiac output; perturbations in active skeletal muscle metabolism may be involved.

  4. Joint US/USSR study: Comparison of effects of horizontal and head-down bed rest

    NASA Technical Reports Server (NTRS)

    Sandler, Harold; Grigoriev, Anatoli I.

    1990-01-01

    An account is given of the results of the first joint U.S./U.S.S.R. bed rest study. The study was accomplished in two parts: A soviet part (May to June 1979) and an American part (July to August 1979). Both studies were conducted under identical conditions and provided a basis for comparison of physiologic reactions and standardizing procedures and methods. Each experiment consisted of three periods: 14 days of pre-bed rest control, 7 days of bed rest, and a 10 to 14 day recovery period. Ten males participated in each study, with five subjects experiencing horizontal bed rest and five subjects a -6 deg head-down body position. Biochemical and hormonal measurements were made of blood and urine, with particular attention to electrolyte metabolism and kidney function; cardio-pulmonary changes at rest and exercise; influence of Lower Body Negative Pressure (LBNP); and incremental exercise using a bicyle ergometer while supine and sitting. Expected moderate changes were noted to occur for various physiologic parameters. Clinical evidence pointed to the fact that head-down bed rest when compared to horizontal conditions more closely matched the conditions seen after manned spaceflight. For the most part, statistically significant differences between the two body positions were not observed.

  5. Effects of head-down bed rest on complex heart rate variability: Response to LBNP testing

    NASA Technical Reports Server (NTRS)

    Goldberger, Ary L.; Mietus, Joseph E.; Rigney, David R.; Wood, Margie L.; Fortney, Suzanne M.

    1994-01-01

    Head-down bed rest is used to model physiological changes during spaceflight. We postulated that bed rest would decrease the degree of complex physiological heart rate variability. We analyzed continuous heart rate data from digitized Holter recordings in eight healthy female volunteers (age 28-34 yr) who underwent a 13-day 6 deg head-down bed rest study with serial lower body negative pressure (LBNP) trials. Heart rate variability was measured on a 4-min data sets using conventional time and frequency domain measures as well as with a new measure of signal 'complexity' (approximate entropy). Data were obtained pre-bed rest (control), during bed rest (day 4 and day 9 or 11), and 2 days post-bed rest (recovery). Tolerance to LBNP was significantly reduced on both bed rest days vs. pre-bed rest. Heart rate variability was assessed at peak LBNP. Heart rate approximate entropy was significantly decreased at day 4 and day 9 or 11, returning toward normal during recovery. Heart rate standard deviation and the ratio of high- to low-power frequency did not change significantly. We conclude that short-term bed rest is associated with a decrease in the complex variability of heart rate during LBNP testing in healthy young adult women. Measurement of heart rate complexity, using a method derived from nonlinear dynamics ('chaos theory'), may provide a sensitive marker of this loss of physiological variability, complementing conventional time and frequency domain statistical measures.

  6. Fluid/electrolyte balance and cardiovascular responses - Head-down tilted rats

    NASA Technical Reports Server (NTRS)

    Musacchia, X. J.; Deavers, D. R.; Meininger, G. A.

    1990-01-01

    Results are presented on cardiovascular and fluid/electrolyte balance responses of rats to a 7-day-long whole-body suspension (WBS) with about 20-deg head-down tilt (HDT), followed by 7 days of recovery. Compared with horizontally positioned (N-HDT) rats serving as controls, the Na intake of HDT rats was significantly reduced during the first 3 days of HDT, and urinary and fecal Na loss exceeded the Na intake during days 5 and 6. Changes during the days of recovery showed adjustments and reestablishment of Na balance. Urinary K losses increased progressively during the 7 days of HDT, but, with the exception of days 1-3 of HDT, when the K intake was significantly reduced, the K balance was retained. Changes in cardiac responses (including elevations in mean, diastolic, and systolic arterial pressures) paralleled changes in fluid and electrolyte balance during the HDT period.

  7. Sympathetic responses to head-down rotations in humans.

    PubMed

    Hume, K M; Ray, C A

    1999-06-01

    Muscle sympathetic nerve activity (MSNA) increases with head-down neck flexion (HDNF). The present study had three aims: 1) to examine sympathetic and vascular responses to two different magnitudes of HDNF; 2) to examine these same responses during prolonged HDNF; and 3) to determine the influence of nonspecific pressure receptors in the head on MSNA. The first experiment tested responses to two static head positions in the vertical axis [HDNF and intermediate HDNF (I-HDNF; approximately 50% of HDNF)]. MSNA increased above baseline during both I-HDNF and HDNF (from 219 +/- 36 to 301 +/- 47 and from 238 +/- 42 to 356 +/- 59 units/min, respectively; P < 0.01). Calf blood flow (CBF) decreased and calf vascular resistance increased during both I-HDNF and HDNF (P < 0.01). Both the increase in MSNA and the decrease in CBF were linearly related to the magnitude of the downward head rotations (P < 0.01). The second experiment tested responses during prolonged HDNF. MSNA increased (from 223 +/- 63 to 315 +/- 79 units/min; P < 0.01) and CBF decreased (from 3.2 +/- 0.4 to 2.6 +/- 0.04 ml. 100 ml-1. min-1; P < 0.01) at the onset of HDNF. These responses were maintained throughout the 30-min period. Mean arterial blood pressure gradually increased during the 30 min of HDNF (from 94 +/- 4 to 105 +/- 3 mmHg; P < 0.01). In a third experiment, head-down neck extension was performed with subjects in the supine position. Unlike HDNF, head-down neck extension did not affect MSNA. The results from these studies demonstrate that MSNA: 1) increases in magnitude as the degree of HDNF increases; 2) remains elevated above baseline during prolonged HDNF; and 3) responses during HDNF are not associated with nonspecific receptors in the head activated by increases in cerebral pressure. PMID:10368363

  8. Effects of 1-week head-down tilt bed rest on bone formation and the calcium endocrine system

    NASA Technical Reports Server (NTRS)

    Arnaud, Sara B.; Whalen, Robert T.; Fung, Paul; Sherrard, Donald J.; Maloney, Norma

    1992-01-01

    The -6-deg head-down tilt (HDT) is employed in the study of 8 subjects to determine early responses in human bone and calcium endocrines during spaceflight. The average rates of bone formation in the iliac crest are determined by means of a single-dose labeling schedule and are found to decrease in 6 of the subjects. The decrease varies directly with walking miles, and increased excretion of urinary Ca and Na are observed preceding increased levels of ionized serum calcium on a bed-rest day late in the week. Reduced phosphorous excretions are also followed by increased serum phosphorous on day six, and reductions are noted in parathyroid hormone and vitamin D by the end of the experiment. The data demonstrate the responsiveness of the skeletal system to biomechanical stimuli such as the HDT.

  9. Cerebral blood flow velocity in humans exposed to 24 h of head-down tilt

    NASA Technical Reports Server (NTRS)

    Kawai, Y.; Murthy, G.; Watenpaugh, D. E.; Breit, G. A.; Deroshia, C. W.; Hargens, A. R.

    1993-01-01

    This study investigates cerebral blood flow (CBF) velocity in humans before, during, and after 24 h of 6 deg head-down tilt (HDT), which is a currently accepted experimental model to simulate microgravity. CBF velocity was measured by use of the transcranial Doppler technique in the right middle cerebral artery of eight healthy male subjects. Mean CBF velocity increased from the pre-HDT upright seated baseline value of 55.5 +/- 3.7 (SE) cm/s to 61.5 +/- 3.3 cm/s at 0.5 h of HDT, reached a peak value of 63.2 +/- 4.1 cm/s at 3 h of HDT, and remained significantly above the pre-HDT baseline for over 6 h of HDT. During upright seated recovery, mean CBF velocity decreased to 87 percent of the pre-HDT baseline value. Mean CBF velocity correlated well with calculated intracranial arterial pressure (IAP). As analyzed by linear regression, mean CBF velocity = 29.6 + 0.32IAP. These results suggest that HDT increases CBF velocity by increasing IAP during several hours after the onset of microgravity. Importantly, the decrease in CBF velocity after HDT may be responsible, in part, for the increased risk of syncope observed in subjects after prolonged bed rest and also in astronauts returning to Earth.

  10. Rat Cardiovascular Responses to Whole Body Suspension: Head-down and Non-Head-Down Tilt

    NASA Technical Reports Server (NTRS)

    Musacchia, X. J.; Steffen, Joseph M.; Dombrowski, Judy

    1992-01-01

    The rat whole body suspension technique mimics responses seen during exposure to microgravity and was evaluated as a model for cardiovascular responses with two series of experiments. In one series, changes were monitored in chronically catheterized rats during 7 days of Head-Down Tilt (HDT) or Non-Head-Down Tilt (N-HDT) and after several hours of recovery. Elevations of mean arterial (MAP), systolic, and diastolic pressures of approx. 20 % (P less than 0.05) in HDT rats began as early as day 1 and were maintained for the duration of suspension. Pulse pressures were relatively unaffected, but heart rates were elevated approx. 10 %. During postsuspension (2-7 h), most cardiovascular parameters returned to presuspension levels. N-HDT rats exhibited elevations chiefly on days 3 and 7. In the second series, blood pressure was monitored in 1- and 3-day HDT and N-HDT rats to evaluate responses to rapid head-up tilt. MAP, systolic and diastolic pressures, and HR were elevated (P less than 0.05) in HDT and N-HDT rats during head-up tilt after 1 day of suspension, while pulse pressures remained un changed. HDT rats exhibited elevated pretilt MAP and failed to respond to rapid head-up tilt with further increase of MAP on day 3, indicating some degree of deconditioning. The whole body suspended rat may be useful as a model to better understand responses of rats exposed to microgravity.

  11. The effect of head-down tilt and water immersion on intracranial pressure in nonhuman primates

    NASA Technical Reports Server (NTRS)

    Keil, Lanny C.; Mckeever, Kenneth H.; Skidmore, Michael G.; Hines, John; Severs, Walter B.

    1992-01-01

    Intracranial pressure (ICP) is investigated in primates during and after -6-deg head-down tilt (HDT) and immersion in water to examine the effects of the headward fluid shift related to spaceflight. Following the HDT the primates are subjected to head-out thermoneutral water immersion, and the ICP is subsequently measured. ICP is found to increase from 3.8 +/- 1.1 to 5.3 +/- 1.3 mm Hg during the horizontal control period. ICP stabilizes at -6.3 +/- 1.3 mm Hg and then increases to -2.2 +/- 1.9 mm Hg during partial immersion, and ICP subsequently returns to preimmersion levels after immersion. These data indicate that exposure to HDT or water immersion lead to an early sharp increase in ICP, and water immersion alone leads to higher ICP levels. A significant conclusion of the work is that the ICP did not approach pathological levels, and this finding is relevant to human spaceflight research.

  12. Cardiovascular dynamics during the initial period of head-down tilt

    NASA Technical Reports Server (NTRS)

    Tomaselli, Clare Marie; Kenney, Richard A.; Frey, Mary Anne Bassett; Hoffler, G. Wyckliffe

    1987-01-01

    The cardiovascular response to 1 h of 60-deg head-down tilt was studied in 12 male subjects, ages 30-39 years, to simulate the early effects of weightlessness. Fluid shifts, hemodynamic variables, and indices of myocardial contractility were evaluated by utilizing electrocardiography, systolic time intervals, impedance cardiography, sphygmomanometry, and measurement of calf circumference. Most cardiovascular variables remained stable throughout the initial 30 min of the protocol, even though translocation of fluid from the legs to the thorax commenced immediately with the onset of head-down tilt. In contrast, minutes 30-60 were characterized by reduced stroke volume, cardiac output, mean stroke ejection rate, and Heather index concomitant with an elevation in mean arterial pressure. Intrathoracic fluid volume continued to increase, while leg volume continued to decrease. This latter physiological response suggests intrathoracic sequestration of fluid volume; blood was apparently redistributed to the pulmonary circulation rather than being retained in the great veins.

  13. Altered thermoregulatory responses after 15 days of head-down tilt

    NASA Technical Reports Server (NTRS)

    Crandall, Craig G.; Johnson, John M.; Convertino, Victor A.; Raven, Peter B.; Engelke, Keith A.

    1994-01-01

    To determine whether extended exposure to a simulation of microgravity alters thermoregulatory reflex control of skin blood flow, six adult males were exposed to 15 days of 6 deg head-down tilt (HDT). On an ambulatory control day before HDT exposure and on HDT day 15 the core temperature of each subject was increased by 0.5 - 1.0 C by whole body heating with a water-perfused suit. Mean skin temperature, oral temperature (T (sub or)), mean arterial pressure, and forearm blood flow were measured throughout the protocol. Forearm vascular conductance (FVC) was calculated from the ratio of forearm blood flow to mean arterial pressure. After HDT exposure, the T(sub or) threshold at which reflex thermally induced increases in FVC began was elevated, whereas the slope of the T(sub or)-FVC relationship after this threshold was reduced. Moreover, normothermic FVC and FVC at the highest common T(sub or) between pre- and post-HDT trials were reduced after HDT. These data suggest that HDT exposure reduces thermoregulatory responses to heat stress. The mechanisms resulting in such an impaired thermoregulatory response are unknown but are likely related to the relative dehydration that accompanies this exposure.

  14. Head-Down Tilt with Balanced Traction as a Model for Simulating Spinal Acclimation to Microgravity

    NASA Technical Reports Server (NTRS)

    Ballard, R. E.; Styf, J. R.; Watenpaugh, D. E.; Fechner, K.; Haruna, Y.; Kahan, N. J.; Hargens, A. R.

    1994-01-01

    Astronauts experience total body height increases of 4 to 7 cm in microgravity. Thus, stretching of the spinal cord, nerve roots, and muscular and ligamentous tissues may be responsible for the hyperreflexia, back pain, and muscular atrophy associated with exposure to microgravity. Axial compression of the spine makes 6 deg. head-down tilt (HDT) an unsuitable model for spinal acclimation to microgravity. However, this axial compression may be counteracted by balanced traction consisting of 10% body weight (sin 6 deg. = 0.1) applied to the legs. Six healthy male subjects underwent 3 days each of 60 HDT with balanced traction and horizontal bed rest (HBR), with a 2 week recovery period between treatments. Total body and spine length, lumbar disc height, back pain, erector spinae intramuscular pressure, and ankle joint torque were measured before, during and after each treatment. Total body and spine (processes of L5 - C7) lengths increased significantly more during HDT with balanced traction (22 +/- 8 mm and 25 +/- 8 mm, respectively) than during HBR (16 +/- 4 mm and 14 +/- 9 mm, respectively). Back and leg pain were significantly greater during HDT with balanced traction than during HBR. The distance between the lower end plate of L4 and the upper endplate of S1, as measured by sonography, increased significantly in both treatments to the same degree (2.9 +/- 1.9 mm, HDT with balanced traction; 3.3 +/- 1.5 mm, HBR). Intramuscular pressure of the erector spinae muscles and maximal ankle joint torque were unaltered with both models. While neither model increased height to the magnitude observed in microgravity, HDT with balanced traction may be a better model for simulating the body lengthening and back pain experienced in microgravity.

  15. Tropospheric Ozone Over a Tropical Atlantic Station in the Northern Hemisphere: Paramaribo, Surinam (6 deg N, 55 deg W)

    NASA Technical Reports Server (NTRS)

    Peters, W.; Krol, M. C.; Fortuin, J. P. F.; Kelder, H. M.; Thompson, A. M.; Becker, C. R.; Lelieveld, J.; Crutzen, P. J.

    2003-01-01

    We present an analysis of 2.5 years of weekly ozone soundings conducted at a new monitoring station in Paramaribo, Surinam (6 deg N,55 deg W). This is currently one of only three ozone sounding stations in the northern hemisphere (NH) tropics, and the only one in the equatorial Atlantic region. Paramaribo is part of the Southern Hemisphere ADditional Ozone Sounding program (SHADOZ). Due to its position close to the equator, the Inter Tropical Convergence Zone (ITCZ) passes over Paramaribo twice per year, which results in a semi-annual seasonality of many parameters including relative humidity and ozone. The dataset from Paramaribo is used to: (1) evaluate ozone variability relative to precipitation, atmospheric circulation patterns and biomass burning; (2) contrast ozone at the NH equatorial Atlantic with that at nearby southern hemisphere (SH) stations Natal (6 deg S,35 deg W) and Ascension (8 deg S,14 deg W); (3) compare the seasonality of tropospheric ozone with a satellite-derived ozone product: Tropical Tropospheric Ozone Columns from the Modified Residual method (MR-TTOC). We find that Paramaribo is a distinctly Atlantic station. Despite its position north of the equator, it resembles nearby SH stations during most of the year. Transport patterns in the lower and middle troposphere during February and March differ from SH stations, which leads to a seasonality of ozone with two maxima. MR-TTOC over Paramaribo does not match the observed seasonality of ozone due to the use of a SH ozone sonde climatology in the MR method. The Paramaribo ozone record is used to suggest an improvement for northern hemisphere MR-TTOC retrievals. We conclude that station Paramaribo shows unique features in the region, and clearly adds new information to the existing SHADOZ record.

  16. Ultrasound measurement of transcranial distance during head-down tilt

    NASA Technical Reports Server (NTRS)

    Torikoshi, S.; Wilson, M. H.; Ballard, R. E.; Watenpaugh, D. E.; Murthy, G.; Yost, W. T.; Cantrell, J. H.; Chang, D. S.; Hargens, A. R.

    1995-01-01

    Exposure to microgravity elevates blood pressure and flow in the head, which may increase intracranial volume (ICV) and intracranial pressure (ICP). Rhesus monkeys exposed to simulated microgravity in the form of 6 degree head-down tilt (HDT) experience elevated ICP. With humans, twenty-four hours of 6 degree HDT bed rest increases cerebral blood flow velocity relative to pre-HDT upright posture. Humans exposed to acute 6 degree HDT experiments increased ICP, measured with the tympanic membrane displacement (TMD) technique. Other studies suggest that increased ICP in humans and cats causes measurable cranial bone movement across the sagittal suture. Due to the slightly compliant nature of the cranium, elevation of the ICP will increase ICV and transcranial distance. Currently, several non-invasive approaches to monitor ICP are being investigated. Such techniques include TMD and modal analysis of the skull. TMD may not be reliable over a large range of ICP and neither method is capable of measuring the small changes in pressure. Ultrasound, however, may reliably measure small distance changes that accompany ICP fluctuations. The purpose of our study was to develop and evaluate an ultrasound technique to measure transcranial distance changes during HDT.

  17. Clementine High Resolution Camera Mosaicking Project. Volume 6; CL 6006; 80 deg N to 80 deg S Latitude, 90 deg E to 120 deg E Longitude; 1

    NASA Technical Reports Server (NTRS)

    Malin, Michael; Revine, Michael; Boyce, Joseph M. (Technical Monitor)

    1998-01-01

    This compact disk (CD) is part of the Malin Space Science Systems (MSSS) effort to mosaic Clementine I high resolution (HiRes) camera lunar images. These mosaics were developed through calibration and semi-automated registration against the recently released geometrically and photometrically controlled Ultraviolet/Visible (UV/Vis) Basemap Mosaic, which is available through the PDS, as CD-ROM volumes CL_3001-3015. The HiRes mosaics are compiled from non-uniformity corrected, 750 nanometer ("D") filter high resolution observations from the HiRes imaging system onboard the Clementine Spacecraft. These mosaics are spatially warped using the sinusoidal equal-area projection at a scale of 20 m/pixel. The geometric control is provided by the 100 m/pixel U.S. Geological Survey (USGS) Clementine Basemap Mosaic compiled from the 750 nm Ultraviolet/Visible Clementine imaging system. Calibration was achieved by removing the image nonuniformity largely caused by the HiRes system's light intensifier. Also provided are offset and scale factors, achieved by a fit of the HiRes data to the corresponding photometrically calibrated UV/Vis basemap that approximately transform the 8-bit HiRes data to photometric units. The mosaics on this CD were compiled from sub-polar data (latitudes 80 degrees South to 80 degrees North; -80 to +80) within the longitude range 0-30 deg E. The mosaics are divided into tiles that cover approximately 1.75 degrees of latitude and span the longitude range of the mosaicked frames. Images from a given orbit are map projected using the orbit's nominal central latitude. This CD contains ancillary data files that support the HiRes mosaic. These files include browse images with UV/Vis context stored in a Joint Photographic Experts Group (JPEG) format, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the "FILES

  18. Gastrointestinal Physiology During Head Down Tilt Bedrest in Human Subjects

    NASA Technical Reports Server (NTRS)

    Vaksman, Z.; Guthienz, J.; Putcha, L.

    2008-01-01

    Introduction: Gastrointestinal (GI) motility plays a key role in the physiology and function of the GI tract. It directly affects absorption of medications and nutrients taken by mouth, in addition to indirectly altering GI physiology by way of changes in the microfloral composition and biochemistry of the GI tract. Astronauts have reported nausea, loss of appetite and constipation during space flight all of which indicate a reduction in GI motility and function similar to the one seen in chronic bed rest patients. The purpose of this study is to determine GI motility and bacterial proliferation during -6 degree head down tilt bed rest (HTD). Methods: Healthy male and female subjects between the ages of 25-40 participated in a 60 day HTD study protocol. GI transit time (GITT) was determined using lactulose breath hydrogen test and bacterial overgrowth was measured using glucose breath hydrogen test. H. Pylori colonization was determined using C13-urea breath test (UBIT#). All three tests were conducted on 9 days before HDT, and repeated on HDT days 2, 28, 58, and again on day 7 after HDT. Results: GITT increased during HTD compared to the respective ambulatory control values; GITT was significantly lower on day 7 after HTD. A concomitant increase in bacterial colonization was also noticed during HDT starting after approximately 28 days of HDT. However, H. Pylori proliferation was not recorded during HDT as indicated by UBIT#. Conclusion: GITT significantly decreased during HDT with a concomitant increase in the proliferation of GI bacterial flora but not H. pylori.

  19. Cardiovascular Adaptations to Long Duration Head Down Tilt Bed Rest

    NASA Technical Reports Server (NTRS)

    Platts, Steven H.; Meck, Janice V.; Martin, David S.; Freeman-Perez, Sondra A.; Riberio, Christine; Garcia, Kathleen M.; Waters, Wendy W.

    2007-01-01

    Orthostatic hypotension is a recognized risk for crewmembers returning from space. Numerous cardiovascular mechanisms have been proposed to account for this problem including vascular and cardiac dysfunction. We studied arterial and cardiac function in 6-degree head-down tilt bed rest, which is the most widely accepted ground-based analog of spaceflight. Eleven subjects are included in this study (8 men and 3 women). Data analysis was limited to the first 49 days, and compared to pre-bed rest baseline data. Using ultrasound, data was collected on arterial diameters and flows at baseline and during reactive hyperemia and following administration of nitroglycerin. Echocardiography was used to acquire information regarding systolic and diastolic function as well as ventricular mass and diameter. Plasma volumes were significantly decreased by 7 days of bed rest and stayed down through 49 days. There were no differences in reactive hyperemic response in the arm at any time point. However, the hyperemic response in the leg was significantly increased at day 49. Arterial responses to nitroglycerin did not change over the duration of bed rest (day effect) in either the arm or leg, but there was a significant difference between the arm and the leg responses. There was a marked decrease in anterior tibial intimal-medial thickness at days 21, 35 and 49. Several cardiac functional parameters including IVRT, Mitral e-wave, ejection time, velocity of circumferential shortening and myocardial performance index were significantly changed following 49 days of bed rest. These data show that some cardiovascular measures change during bed rest, while others do not. Further study is needed to determine if these measures can provide any insight into the effects of bed rest, or spaceflight, on human cardiovascular performance.

  20. Pathway Concepts Experiment for Head-Down Synthetic Vision Displays

    NASA Technical Reports Server (NTRS)

    Prinzel, Lawrence J., III; Arthur, Jarvis J., III; Kramer, Lynda J.; Bailey, Randall E.

    2004-01-01

    Eight 757 commercial airline captains flew 22 approaches using the Reno Sparks 16R Visual Arrival under simulated Category I conditions. Approaches were flown using a head-down synthetic vision display to evaluate four tunnel ("minimal", "box", "dynamic pathway", "dynamic crow s feet") and three guidance ("ball", "tadpole", "follow-me aircraft") concepts and compare their efficacy to a baseline condition (i.e., no tunnel, ball guidance). The results showed that the tunnel concepts significantly improved pilot performance and situation awareness and lowered workload compared to the baseline condition. The dynamic crow s feet tunnel and follow-me aircraft guidance concepts were found to be the best candidates for future synthetic vision head-down displays. These results are discussed with implications for synthetic vision display design and future research.

  1. Effects of prolonged head-down bed rest on working memory

    PubMed Central

    Liu, Qing; Zhou, Renlai; Zhao, Xin; Oei, Tian Po S

    2015-01-01

    Background The weightlessness caused by prolonged bed rest results in changes in cerebral circulation and thus, brain functions, which is of interest. Methods We investigated the effects of 45-day, −6° head-down bed rest, which stimulated microgravity, on working memory in 16 healthy male participants. The 2-back task was used to test the working memory variations on the 2nd day before bed rest (R−2); on the 11th (R11), 20th (R20), 32nd (R32), and 40th (R40) days of bed rest; and on the eighth day after bed rest (R+8). The cognitive response and the physiological reactivity (such as galvanic skin response, heart rate, and heart rate variability) under the 2-back task were recorded simultaneously. Results The results showed that compared with R−2, on the R+8, the participants’ galvanic skin response increased significantly, and the high frequency of heart rate variability (HF), low frequency of heart rate variability (LF), and reaction time in the 2-back task decreased significantly. There were positive correlations between the participants’ reaction time of working memory and the LF/HF under head-down bed rest (at R11, R20, and R32). Conclusion The results suggested that the prolonged head-down bed rest may have a detrimental effect on individual physiology and working memory. Physiology indices, such as galvanic skin response and heart rate variability, were sensitive to the prolonged bed rest. PMID:25848281

  2. Ocular Outcomes Comparison Between 14- and 70-day Head-down Tilt Bed Rest

    NASA Technical Reports Server (NTRS)

    Cromwell, R.L.; Taibbi, G.; Zanello, S.B.; Yarbough, P.O.; Ploutz-Snyder, R.J.; Vizzen, G.

    2015-01-01

    INTRODUCTION: Ophthalmological changes, including optic disc edema with optic nerve sheath distension, posterior globe flattening with hyperopic shift, choroidal folds and cotton wool spots have been detected in some astronauts involved in long-duration spaceflights. (sup 1) It is hypothesized that elevated intracranial pressure resulting from microgravity-induced cephalad fluid shifts may be responsible for most of these findings. Head-down tilt bed rest (HTDBR) is a ground-based microgravity analog which also produces cephalad fluid shifts. It is conceivable that prolonged HDTBR exposure may induce ocular changes similar to those experienced in microgravity. Therefore, the purpose of the present study was to compare structural and functional ocular outcomes between 14- and 70-day HDTBR in healthy human subjects. It is hypothesized that 70-d HDTBR induced ocular changes of greater magnitude as compared to 14-d HDTBR. METHODS: Two HDTBR studies were conducted at the NASA Flight Analogs Research Unit, located at The University of Texas Medical Branch at Galveston, TX. Identical NASA standard screening procedures and BR conditions (e.g., strict sleep-wake cycle, standardized diet, continuous video monitoring) were implemented in both studies. Participants spent 14 and/or 70 consecutive days in a 6deg HDT position and did not engage in exercise. Subjects received weekly ocular examinations before, during, and after HDTBR. Ocular testing included: distance and near best-corrected visual acuity (BCVA), cycloplegic refraction, intraocular pressure (IOP) measurement, color vision, red dot test, modified Amsler grid test, confrontational visual field, color fundus photography and Spectral-domain OCT scans of the macula and the optic disc. Pre/post HDTBR differences between the two studies will be evaluated for BCVA, spherical equivalent, IOP, retinal nerve fiber layer (RNFL) thickness and macular OCT parameters. RESULTS: 16 (12 males and 4 females) and 6 (5 males and 1

  3. Hypersonic, nonequilibrium flow over a cylindrically blunted 6 deg wedge

    NASA Technical Reports Server (NTRS)

    Gnoffo, Peter A.

    1993-01-01

    The numerical simulation of hypersonic flow in chemical nonequilibrium over cylindrically blunted 6 degree wedge is described. The simulation was executed on a Cray C-90 with Program LAURA 92-vl. Code setup procedures and sample results, including grid refinement studies and variations of species number are discussed. This simulation relates to a study of wing leading edge heating on transatmospheric vehicles.

  4. Infrared astronomical satellite (IRAS) catalogs and atlases. Volume 6: The point source catalog declination range -50 deg greater than delta greater than -90 deg

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The Infrared Astronomical Satellite (IRAS) was launched January 26, 1983. During its 300-day mission, it surveyed over 96 pct of the celestial sphere at four infrared wavelengths, centered approximately at 12, 25, 60, and 100 microns. This is Volume 6, The Point Source Catalog Declination Range -50 deg greater than delta greater than -90 deg.

  5. Three dimensional audio versus head down TCAS displays

    NASA Technical Reports Server (NTRS)

    Begault, Durand R.; Pittman, Marc T.

    1994-01-01

    The advantage of a head up auditory display was evaluated in an experiment designed to measure and compare the acquisition time for capturing visual targets under two conditions: Standard head down traffic collision avoidance system (TCAS) display, and three-dimensional (3-D) audio TCAS presentation. Ten commercial airline crews were tested under full mission simulation conditions at the NASA Ames Crew-Vehicle Systems Research Facility Advanced Concepts Flight Simulator. Scenario software generated targets corresponding to aircraft which activated a 3-D aural advisory or a TCAS advisory. Results showed a significant difference in target acquisition time between the two conditions, favoring the 3-D audio TCAS condition by 500 ms.

  6. A Conjugate Study of Mean Winds and Planetary Waves Employing Enhanced Meteor Radars at Rio Grande, Argentina (53.8degS) and Juliusruh, Germany (54.6degN)

    NASA Technical Reports Server (NTRS)

    Fritts, D. C.; Imura, H.; Lieberman, R.; Janches, D.; Singer, W.

    2011-01-01

    Two meteor radars with enhanced power and sensitivity and located at closely conjugate latitudes (54.6degN and 53.8degS) are employed for inter-hemispheric comparisons of mean winds and planetary wave structures. Our study uses data from June 2008 through May 2010 during which both radars provided nearly continuous wind measurements from approx.80 to 100 km. Monthly mean winds at 53.8degS exhibit a somewhat stronger westward mean zonal jet in spring and early summer at lower altitudes and no westward monthly mean winds at higher altitudes. In contrast, westward mean winds of approx.5-10 m/s at 54.6degN extend to above 96 km during late winter and early spring each year. Equatorward monthly mean winds extend approximately from spring to fall equinox at both latitudes, with amplitudes of approx.5-10 m/s and more rapid decreases in amplitude at 54.6degN at higher altitudes. Meridional mean winds are more variable at both latitudes during fall and winter, with both poleward and equatorward monthly means indicating longer-period variability. Planetary waves seen in the 2-day mean data are episodic and variable at both sites, exhibit dominant periodicities of approx.8-10 and 16-20 days and are more confined to late fall and winter at 54.6degN. At both latitudes, planetary waves in the two period bands coincide closely in time and exhibit similar horizontal velocity covariances that are positive (negative) at 54.6degN (53.8degS) during peak planetary wave responses.

  7. Pulmonary responses to lower body negative pressure and fluid loading during head-down tilt bedrest.

    PubMed

    Hillebrecht, A; Schulz, H; Meyer, M; Baisch, F; Beck, L; Blomqvist, C G

    1992-01-01

    Exposure to microgravity redistributes body fluids with important secondary effects on cardiovascular function. We tested the hypothesis that the fluid shifts also affect pulmonary gas exchange. Microgravity was simulated in six male volunteers by a 10-day period of bedrest at 6 degrees head-down tilt (HDT). Lower body negative pressure (LBNP) and intravenous saline loading superimposed acute changes in fluid distribution on the prolonged effects of HDT. HDT produced relative dehydration and hypovolemia with decreased pulmonary blood flow and diffusing capacity. Before bedrest, pulmonary blood flow decreased by 24% during LBNP and diffusing capacity by 7%, while functional residual capacity increased by 14% (p less than 0.05). Intravenous saline loading caused a 24% increase in pulmonary blood-flow (p less than 0.05). Functional residual capacity decreased by 10% and diffusing capacity by 6% (p less than 0.05). Lung tissue volume did not change significantly. Head-down tilt had only minor effects on the responses to LBNP and saline loading. We conclude that LBNP and intravenous saline loading produce major changes in pulmonary blood-flow and minor effects on pulmonary gas exchange, and that the response to acute changes in fluid distribution is not significantly altered during simulated microgravity. PMID:1509892

  8. Effects of acute hypoxia on cardiopulmonary responses to head-down tilt

    NASA Technical Reports Server (NTRS)

    Loeppky, J. A.; Luft, U. C.; Scotto, P.; Chick, T. W.

    1990-01-01

    Six male subjects were exposed on two separate occasions to simulated microgravity with 28 deg head-down tilt (HD) for 1 h with baseline followed by recovery at + 17 deg head-up. Pulmonary ventilation, gas exchange, spirometry, and central and cerebral blood flow characteristics were compared while breathing ambient air and reduced F(I)O2 equivalent to 14,828 ft. With hypoxia (HY), the increased tidal volume served to attenuate the drop in arterial saturation by reducing deadspace ventilation. Arterial and mixed venous PO2, values, estimated from peripheral venous samples and cardiac output (CO), were both maintained during HD in HY. Mixed venous PO2 was elevated by an increase in CO associated with a reduction in systemic resistance. Changes in spirometric indices during HD were not accentuated by HY, making the presence of interstitial edema unlikely. Cerebral flow and resistance showed minor reductions with HD. Tissue oxygenation and cardiopulmonary function were not notably effected by HD during HY, but a combination of these two stressors may predispose subjects to subsequent orthostatic intolerance during initial recovery.

  9. Cardiopulmonary function during 10 days of head-down tilt bedrest.

    PubMed

    Schulz, H; Hillebrecht, A; Karemaker, J M; ten Harkel, A D; Beck, L; Baisch, F; Meyer, M

    1992-01-01

    Pulmonary and cardiovascular responses to simulated weightlessness, i. e. 6 degrees head-down tilt bedrest (HDT) were investigated in six healthy male volunteers (mean age 26 yrs). Pulmonary diffusing capacity, functional residual capacity, pulmonary capillary blood flow, and lung tissue volume were measured by inert gas rebreathing. Heart rate and mean arterial blood pressure were obtained from finger blood pressure readings using a plethysmographic technique (Finapres). The short-term (20 min) response to HDT consisted of a 22% increase in pulmonary blood flow, and 13% and 31% falls in blood pressure and heart rate relative to standing. Functional residual capacity fell by 33%, while lung tissue volume increased insignificantly. Subsequent measurements during 10 days of HDT and 5 days of recovery revealed no further changes in lung volume, lung tissue volume, or blood pressure. However, diffusing capacity fell gradually and remained 4%-5% below baseline values after the 7th day of bedrest and during recovery (p less than 0.05). Pulmonary blood flow decreased by 16% during head-down bedrest and recovered partially within the following 5 days (p less than 0.05). We conclude that during and after simulated weightlessness marked alterations in cardiovascular function and marginal affections of gas exchange can be demonstrated already at rest. They may be considered as contributing factors to orthostatic and exercise intolerance observed after space flight. PMID:1509891

  10. A Mars Pathfinder landing on a recently drained ephemeral sea: Cerberus Plains, 6 deg N, 188 deg W

    NASA Technical Reports Server (NTRS)

    Brakenridge, G. Robert

    1994-01-01

    Along a 500 km-wide belt extending between 202 deg and 180 deg W and lying astride the martian equator, moderately low-albedo, uncratered smooth plains exhibit low thermal inertia and potentially favorable conditions for the preservation of near-surface ice. The Cerberus Plains occupy a topographic trough as much as 2 km below the planetary datum, and the denser atmosphere at these altitudes would also favor long residence times for near-surface ice once emplaced. The plains have previously been interpreted as the result of young (late Amazonian) low viscosity lava flows or similarly youthful fluvial deposition. However, the plains are also included in maps of possibly extensive martian paleoseas or paleolakes. Ice emplaced as such seas dissipated could still be preserved under thin (a few tens of centimeters) sedimentary cover. In any case, and if a sea once existed, aqueous-born interstitial cementation, probably including hydrated iron oxides and sulfate minerals, would have been favored and is now susceptible to investigation by the Pathfinder alpha proton x-ray spectrometer and multispectral imager.

  11. Terrain Portrayal for Head-Down Displays Experiment

    NASA Technical Reports Server (NTRS)

    Hughes, Monica F.; Takallu, M. A.

    2002-01-01

    The General Aviation Element of the Aviation Safety Program's Synthetic Vision Systems (SVS) Project is developing technology to eliminate low visibility induced General Aviation (GA) accidents. SVS displays present computer generated 3-dimensional imagery of the surrounding terrain on the Primary Flight Display (PFD) to greatly enhance pilot's situation awareness (SA), reducing or eliminating Controlled Flight into Terrain, as well as Low-Visibility Loss of Control accidents. SVS-conducted research is facilitating development of display concepts that provide the pilot with an unobstructed view of the outside terrain, regardless of weather conditions and time of day. A critical component of SVS displays is the appropriate presentation of terrain to the pilot. An experimental study has been conducted at NASA Langley Research Center (LaRC) to explore and quantify the relationship between the realism of the terrain presentation and resulting enhancements of pilot SA and pilot performance. Composed of complementary simulation and flight test efforts, Terrain Portrayal for Head-Down Displays (TP-HDD) experiments will help researchers evaluate critical terrain portrayal concepts. The experimental effort is to provide data to enable design trades that optimize SVS applications, as well as develop requirements and recommendations to facilitate the certification process. This paper focuses on the experimental set-up and preliminary qualitative results of the TP-HDD simulation experiment. In this experiment a fixed based flight simulator was equipped with various types of Head Down flight displays, ranging from conventional round dials (typical of most GA aircraft) to glass cockpit style PFD's. The variations of the PFD included an assortment of texturing and Digital Elevation Model (DEM) resolution combinations. A test matrix of 10 terrain display configurations (in addition to the baseline displays) were evaluated by 27 pilots of various backgrounds and experience levels

  12. Catecholaminergic effects of prolonged head-down bed rest

    NASA Technical Reports Server (NTRS)

    Goldstein, D. S.; Vernikos, J.; Holmes, C.; Convertino, V. A.

    1995-01-01

    Prolonged head-down bed rest (HDBR) provides a model for examining responses to chronic weightlessness in humans. Eight healthy volunteers underwent HDBR for 2 wk. Antecubital venous blood was sampled for plasma levels of catechols [norepinephrine (NE), epinephrine, dopamine, dihydroxyphenylalanine, dihydroxyphenylglycol, and dihydroxyphenylacetic acid] after supine rest on a control (C) day and after 4 h and 7 and 14 days of HDBR. Urine was collected after 2 h of supine rest during day C, 2 h before HDBR, and during the intervals 1-4, 4-24, 144-168 (day 7), and 312-336 h (day 14) of HDBR. All subjects had decreased plasma and blood volumes (mean 16%), atriopeptin levels (31%), and peripheral venous pressure (26%) after HDBR. NE excretion on day 14 of HDBR was decreased by 35% from that on day C, without further trends as HDBR continued, whereas plasma levels were only variably and nonsignificantly decreased. Excretion rates of dihydroxyphenylglycol and dihydroxyphenylalanine decreased slightly during HDBR; excretion rates of epinephrine, dopamine, and dihydroxyphenylacetic acid and plasma levels of catechols were unchanged. The results suggest that HDBR produces sustained inhibition of sympathoneural release, turnover, and synthesis of NE without affecting adrenomedullary secretion or renal dopamine production. Concurrent hypovolemia probably interferes with detection of sympathoinhibition by plasma levels of NE and other catechols in this setting. Sympathoinhibition, despite decreased blood volume, may help to explain orthostatic intolerance in astronauts returning from spaceflights.

  13. Consideration of technologies for head-down displays

    NASA Astrophysics Data System (ADS)

    Bartlett, Christopher T.

    1998-09-01

    The market for military avionics head down displays for which Active Matrix Liquid Crystal Displays (AMLCD) has been specified is both well established and substantial. Typical major programs such as F-22, V-22 and Joint Strike Fighter (JSF) amount to over 15,000 displays. Nevertheless there is an insecurity about the situation because of the dependency upon Japanese and Korean manufacturers and the vagaries of the commercial market. The U.S. has only 7% of the world's manufacturing capability in AMLCD and is seeking alternative technologies to regain a hold in this lucrative business. The U.S. military manufacturers of AMLCD are capable, but can never achieve the benefits of scale that Commercial Off The Shelf (COTS) equipment can offer. In addition to the commercial and political concerns, there are still performance issues related to AMLCD and there is a view that emissive displays in particular can offer advantages over AMLCD. However, it is beneficial to be able to tailor display sizes and there are doubts about the ability of current flat panel technologies to achieve custom, or indeed large area panels either economically, or reliably. It is in this arena that projection displays may be the optimum solution.

  14. Analogs of microgravity: head-down tilt and water immersion.

    PubMed

    Watenpaugh, Donald E

    2016-04-15

    This article briefly reviews the fidelity of ground-based methods used to simulate human existence in weightlessness (spaceflight). These methods include horizontal bed rest (BR), head-down tilt bed rest (HDT), head-out water immersion (WI), and head-out dry immersion (DI; immersion with an impermeable elastic cloth barrier between subject and water). Among these, HDT has become by far the most commonly used method, especially for longer studies. DI is less common but well accepted for long-duration studies. Very few studies exist that attempt to validate a specific simulation mode against actual microgravity. Many fundamental physical, and thus physiological, differences exist between microgravity and our methods to simulate it, and between the different methods. Also, although weightlessness is the salient feature of spaceflight, several ancillary factors of space travel complicate Earth-based simulation. In spite of these discrepancies and complications, the analogs duplicate many responses to 0 G reasonably well. As we learn more about responses to microgravity and spaceflight, investigators will continue to fine-tune simulation methods to optimize accuracy and applicability. PMID:26869710

  15. Hormonal changes during 17 days of head-down bed-rest

    NASA Technical Reports Server (NTRS)

    Custaud, Marc-Antoine; Arnaud, Sara B.; Monk, Timothy H.; Claustrat, Bruno; Gharib, Claude; Gauquelin-Koch, Guillemette

    2003-01-01

    We investigated in six men the impact of 17 days of head-down bed rest (HDBR) on the daily rhythms of the hormones involved in hydroelectrolytic regulation. This HDBR study was designed to mimic a real space flight. Urine samples were collected at each voiding before, during and after HDBR. Urinary excretion of Growth Hormone (GH), Cortisol, 6 Sulfatoxymelatonin, Normetadrenaline (NMN) and Metadrenaline (NM) was determined. A decrease in urinary cortisol excretion during the night of HDBR was noted. For GH, a rhythm was found before and during HDBR. The rhythm of melatonin, evaluated with the urine excretion of 6 Sulfatoxymelatonin (aMT6S), the main hepatic metabolite, persisted throughout the experiment without any modification to the level of phase. A decrease during the night was noted for normetadrenaline urinary derivates, but only during the HDBR.

  16. Immune response to 60-day head-down bed rest

    NASA Astrophysics Data System (ADS)

    Song, Jinping; Guo, Aihua; Zhong, Ping; Zhang, Hongyu; Wu, Feng; Wan, Yumin; Bai, Yanqiang; Chen, Shanguang; Li, Yinghui

    Introduction: Exposure of humans to spaceflight has resulted in disregulation of the immune system. Head-down bed rest (HDBR) has been extensively used as an earth-bound analog to study physiologic effects mimicking those occurring in weightlessness during spaceflight. It is uncertain how a prolonged period of bed rest affect human immune responses. The objective of this study was to investigate the effects of 60-day HDBR on immune function and EB virus reactivation in seven male volunteers. Methods: There were seven healthy male volunteers who were subjected to HDBR for 60d. Immunological parameters including leukocyte subset distribution, lymphocyte proliferation to mitogens, secreted cytokine profiles and EB virus reactivation were monitored. Results: Total WBC conunts increased significantly 10d post-HDBR as compared with pre-HDBR. At the same time, the relative percentage of neutrophils was also higher than pre-HDBR but not significant. MFI of CD11b in neutrophils was reduced obviously at thd end of HDBR. T Lymphocyte proliferations to PHA reduced at HDBR 30, HDBR 60 and 10d post-HDBR while IL-2 production decreased significantly at the same time. IFN-and IL-4 production trended to decrease at HDBR 30 and HDBR 60. The relative percentage of T lymphocyte subset, B lymphocyte and NK cells were not altered. EBV EA (early antigen) were negative and EBV VCA titers had no changes through HDBR. Conclusion: The results indicate that several immunological parameters (mainly cellular immunity) are altered significantly by prolonged HDBR, and these changes were similar to those happened in spaceflight.

  17. Metabolic responses to head-down suspension in hypophysectomized rats

    NASA Technical Reports Server (NTRS)

    Woodman, C. R.; Tipton, C. M.; Evans, J.; Linderman, J. K.; Gosselink, K.; Grindeland, R. E.

    1993-01-01

    Rats exposed to head-down suspension (HDS) exhibit reductions in maximal O2 consumption (VO2max) and atrophy of select hindlimb muscles. This study tested the hypothesis that an endocrine-deficient rat exposed to HDS would not exhibit reductions in VO2max or hindlimb muscle mass. Hypophysectomized (HYPX) and sham-operated (SHAM) rats were tested for VO2max before and after 28 days of HDS or cage control (CC) conditions. No significant reductions in VO2max were observed in HYPX rats. In contrast, SHAM-HDS rats exhibited a significant reduction in absolute (-16%) and relative (-29%) measures of aerobic capacity. Time course experiments revealed a reduction in VO2max in SHAM-HDS rats within 7 days, suggesting that cardiovascular adjustments to HDS occurred in the 1st wk. HDS was associated with atrophy of the soleus (-42%) in SHAM rats, whereas HYPX rats exhibited atrophy of the soleus (-36%) and plantaris (-13%). SHAM-HDS rats had significantly lower (-38%) soleus citrate synthase activities per gram muscle mass than SHAM-CC, but no significant differences existed between HYPX-HDS and -CC rats. HDS rats had an impaired ability to thermoregulate, as indicated by significantly greater temperature increases per unit run time, compared with their CC counterparts. Pretreatment plasma epinephrine levels were significantly lower in HYPX than in SHAM rats. Norepinephrine concentration was similar for all groups except HYPX-HDS, in which it was significantly higher. HDS had no significant effect on thyroxine or triiodothyronine. SHAM-HDS rats had significantly lower concentrations of testosterone and growth hormone.(ABSTRACT TRUNCATED AT 250 WORDS).

  18. Body fluid alterations during head-down bed rest in men at moderate altitude

    NASA Technical Reports Server (NTRS)

    Loeppky, J. A.; Roach, R. C.; Selland, M. A.; Scotto, P.; Luft, F. C.; Luft, U. C.

    1993-01-01

    To determine the effects of hypoxia on fluid balance responses to simulated zero-gravity, measurements were made in six subjects before and during -5 deg continuous head-down bed rest (HDBR) over 8 d at 10,678 ft. The same subjects were studied again at this altitude without HDBR as a control (CON) using a cross-over design. During this time, they maintained normal upright day-time activities, sleeping in the horizontal position at night. Fluid balance changes during HDBR in hypoxia were more pronounced than similar measurements previously reported from HDBR studies at sea level. Plasma volume loss was slightly greater and the diuresis and natriuresis were doubled in magnitude as compared to previous studies in normoxia and sustained for 4 d during hypoxia. These changes were associated with an immediate but transient rise in plasma atrial natriuretic peptide (ANP) to day 4 of 140 percent in HDBR and 41 percent in CON (p less than 0.005), followed by a decline towards baseline. Differences were less striking between HDBR and CON for plasma antidiuretic hormone and aldosterone, which were transiently reduced by HDBR. Plasma catecholamines showed a similar pattern to ANP in both HDBR and CON, suggesting that elevated ANP and catecholamines together accounted for the enhanced fluid shifts with HDBR during hypoxia.

  19. The NASA performance assessment workstation: Cognitive performance during head-down bed rest

    NASA Astrophysics Data System (ADS)

    Shehab, Randa L.; Schlegel, Robert E.; Schiflett, Samuel G.; Eddy, Douglas R.

    The NASA Performance Assessment Workstation was used to assess cognitive performance changes in eight males subjected to seventeen days of 6 ° head-down bed rest. PAWS uses six performance tasks to assess directed and divided attention, spatial, mathematical, and memory skills, and tracking ability. Subjective scales assess overall fatigue and mood state. Subjects completed training trials, practice trials, bed rest trials, and recovery trials. The last eight practice trials and all bed rest trials were performed with subjects lying face-down on a gurney. In general, there was no apparent cumulative effect of bed rest. Following a short period of performance stabilization, a slight but steady trend of performance improvement was observed across all trials. For most tasks, this trend of performance improvement was enhanced during recovery. No statistically significant differences in performance were observed when comparing bed rest with the control period. Additionally, fatigue scores showed little change across all periods.

  20. Five days of head-down-tilt bed rest induces noninflammatory shedding of L-selectin.

    PubMed

    Feuerecker, M; Feuerecker, B; Matzel, S; Long, M; Strewe, C; Kaufmann, I; Hoerl, M; Schelling, G; Rehm, M; Choukèr, A

    2013-07-15

    Head-down-tilt bed rest (HDTBR) is a popular model, simulating alterations of gravitation during space missions. The aim of this study was to obtain a better insight into the complexly orchestrated regulations of HDTBR-induced immunological responses, hypothesizing that artificial gravity can mitigate these HDTBR-related physiological effects. This crossover-designed 5 days of HDTBR study included three protocols with no, or daily 30 min of centrifugation or 6 × 5 min of centrifugation. Twelve healthy, male participants donated blood pre-HDTBR, post-HDTBR, and twice during HDTBR. Cellular immune changes were assessed either by enumerative and immune cell phenotyping assays or by functional testing of responses to either recall antigens or receptor-dependent activation by chemotactic agents N-formyl-methionyl-leucyl-phenylalanine (fMLP) and with TNF-α. The expression of the adhesion molecule L-selectin (CD62L) on the surface of granulocytes and its shedding into plasma samples were measured. In parallel, other humoral factor, such as interleukin-6 and interleukin-8, parameters of endothelial damage (glycocalyx) were determined. Hematocrit and hemoglobin were significantly increased during HDTBR. Although immune functional tests did not indicate a change in the immune performance, the expression of CD62L on resting granulocytes was significantly shed by 50% during HDTBR. Although the latter is normally associated to an activation of inflammatory innate immune responses and during interaction of granulocytes with the endothelium, CD62L shedding was, however, not related either to a systemic inflammatory alteration or to shedding of the endothelial glycocalyx during bed rest. This suggests a noninflammatory or "mechanical" shedding related to fluid shifts during head-down intervention and not to an acute inflammatory process. PMID:23681910

  1. Psychoneuroendocrine alterations during 5 days of head-down tilt bed rest and artificial gravity interventions.

    PubMed

    Choukèr, A; Feuerecker, B; Matzel, S; Kaufmann, I; Strewe, C; Hoerl, M; Schelling, G; Feuerecker, M

    2013-08-01

    This study aimed to investigate psychological stress and endocrine responses during 5 days of head-down tilt bed rest (HDTBR) with or without the impact of artificial gravity (AG). Participants were assigned to one of three bed-rest-protocols either with (i) no centrifugation, (ii) continuous 30 min (AG1) or (iii) discontinuous 6 × 5 min (AG2) centrifugation periods at 1G in the center of mass periods. Centrifugations were performed daily in one session. Questionnaires for assessing psychological stress and the corresponding biological sample collection were performed before, during and after HDTBR or centrifugation. Overall, questionnaires showed no significant changes of anxiety or emotional stress during HDTBR. In the AG1-group, salivary cortisol levels were significantly higher after centrifugation irrespective of the progress of the HDTBR and day of intervention. The AG2-group showed higher cortisol concentrations after centrifugation only on the first days of head-down tilt but no more on day 5 of HDTBR. During bed rest, urine epinephrine excretion increased in all groups, but showed the highest day concentrations in the AG1-group, which were also significantly higher when compared with AG2. These results indicate that 5 days of HDT alone is not a major stressor and accordingly resulted only in moderate changes of neuroendocrine responses over time. However, daily centrifugation for a continuous duration of 30 min induced a significant neuroendocrine response, which was not subject to a habituation as compared with daily but intermittent centrifugation for 6 × 5 min. Discontinuous centrifugation is better tolerated and associated with lower adrenocortical stress responses during HDTBR. PMID:23579361

  2. Terrain Portrayal for Head-Down Displays Flight Test

    NASA Technical Reports Server (NTRS)

    Hughes, Monica F.; Glaab, Louis J.

    2003-01-01

    The Synthetic Vision Systems General Aviation (SVS-GA) element of NASA's Aviation Safety Program is developing technology to eliminate low visibility induced General Aviation (GA) accidents through the application of synthetic vision techniques. SVS displays present computer generated 3-dimensional imagery of the surrounding terrain to greatly enhance pilot's situation awareness (SA), reducing or eliminating Controlled Flight into Terrain (CFIT), as well as Low-Visibility Loss of Control (LVLOC) accidents. In addition to substantial safety benefits, SVS displays have many potential operational benefits that can lead to flight in instrument meteorological conditions (IMC) resembling those conducted in visual meteorological conditions (VMC). Potential benefits could include lower landing minimums, more approach options, reduced training time, etc. SVS conducted research will develop display concepts providing the pilot with an unobstructed view of the outside terrain, regardless of weather conditions and time of day. A critical component of SVS displays is the appropriate presentation of terrain to the pilot. The relationship between the realism of the terrain presentation and resulting enhancements of pilot SA and pilot performance has been largely undefined. Comprised of coordinated simulation and flight test efforts, the terrain portrayal for head-down displays (TP-HDD) test series examined the effects of two primary elements of terrain portrayal: variations of digital elevation model (DEM) resolution and terrain texturing. Variations in DEM resolution ranged from sparsely spaced (30 arc-sec/2,953ft) to very closely spaced data (1 arc-sec/98 ft). Variations in texture involved three primary methods: constant color, elevation-based generic, and photo-realistic, along with a secondary depth cue enhancer in the form of a fishnet grid overlay. The TP-HDD test series was designed to provide comprehensive data to enable design trades to optimize all SVS applications, as

  3. Increased Brain Activation for Dual Tasking with 70-Days Head-Down Bed Rest.

    PubMed

    Yuan, Peng; Koppelmans, Vincent; Reuter-Lorenz, Patricia A; De Dios, Yiri E; Gadd, Nichole E; Wood, Scott J; Riascos, Roy; Kofman, Igor S; Bloomberg, Jacob J; Mulavara, Ajitkumar P; Seidler, Rachael D

    2016-01-01

    Head-down tilt bed rest (HDBR) has been used as a spaceflight analog to simulate the effects of microgravity exposure on human physiology, sensorimotor function, and cognition on Earth. Previous studies have reported that concurrent performance of motor and cognitive tasks can be impaired during space missions. Understanding the consequences of HDBR for neural control of dual tasking may possibly provide insight into neural efficiency during spaceflight. In the current study, we evaluated how dual task performance and the underlying brain activation changed as a function of HDBR. Eighteen healthy men participated in this study. They remained continuously in the 6° head-down tilt position for 70 days. Functional MRI for bimanual finger tapping was acquired during both single task and dual task conditions, and repeated at 7 time points pre-, during- and post-HDBR. Another 12 healthy males participated as controls who did not undergo HDBR. A widely distributed network involving the frontal, parietal, cingulate, temporal, and occipital cortices exhibited increased activation for dual tasking and increased activation differences between dual and single task conditions during HDBR relative to pre- or post-HDBR. This HDBR-related brain activation increase for dual tasking implies that more neurocognitive control is needed for dual task execution during HDBR compared to pre- and post-HDBR. We observed a positive correlation between pre-to-post HDBR changes in dual-task cost of reaction time and pre-to-post HDBR change in dual-task cost of brain activation in several cerebral and cerebellar regions. These findings could be predictive of changes in dual task processing during spaceflight. PMID:27601982

  4. Increased Brain Activation for Dual Tasking with 70-Days Head-Down Bed Rest

    PubMed Central

    Yuan, Peng; Koppelmans, Vincent; Reuter-Lorenz, Patricia A.; De Dios, Yiri E.; Gadd, Nichole E.; Wood, Scott J.; Riascos, Roy; Kofman, Igor S.; Bloomberg, Jacob J.; Mulavara, Ajitkumar P.; Seidler, Rachael D.

    2016-01-01

    Head-down tilt bed rest (HDBR) has been used as a spaceflight analog to simulate the effects of microgravity exposure on human physiology, sensorimotor function, and cognition on Earth. Previous studies have reported that concurrent performance of motor and cognitive tasks can be impaired during space missions. Understanding the consequences of HDBR for neural control of dual tasking may possibly provide insight into neural efficiency during spaceflight. In the current study, we evaluated how dual task performance and the underlying brain activation changed as a function of HDBR. Eighteen healthy men participated in this study. They remained continuously in the 6° head-down tilt position for 70 days. Functional MRI for bimanual finger tapping was acquired during both single task and dual task conditions, and repeated at 7 time points pre-, during- and post-HDBR. Another 12 healthy males participated as controls who did not undergo HDBR. A widely distributed network involving the frontal, parietal, cingulate, temporal, and occipital cortices exhibited increased activation for dual tasking and increased activation differences between dual and single task conditions during HDBR relative to pre- or post-HDBR. This HDBR-related brain activation increase for dual tasking implies that more neurocognitive control is needed for dual task execution during HDBR compared to pre- and post-HDBR. We observed a positive correlation between pre-to-post HDBR changes in dual-task cost of reaction time and pre-to-post HDBR change in dual-task cost of brain activation in several cerebral and cerebellar regions. These findings could be predictive of changes in dual task processing during spaceflight. PMID:27601982

  5. Effects of Resistive Vibration Exercise Combined with Whey Protein and KHCO3 on Bone Tturnover Markers in Head-down Tilt Bed Rest (MTBR-MNX Study)

    NASA Technical Reports Server (NTRS)

    Graf, Sonja; Baecker, Natalie; Buehlmeier, Judith; Fischer, Annelie; Smith, Scott M.; Heer, Martina

    2014-01-01

    High protein intake further increases bone resorption markers in head-down tilt bed rest (HDBR), most likely induced by low-grade metabolic acidosis. Adding an alkaline salt to a diet with high protein content prevents this additional rise of bone resorption markers in HDBR. In addition, high protein intake, specifically whey protein, increases muscle protein synthesis and improves glucose tolerance, which both are affected by HDBR. Resistive vibration exercise (RVE) training counteracts the inactivity-induced bone resorption during HDBR. To test the hypothesis that WP plus alkaline salt (KHCO3) together with RVE during HDBR will improve bone turnover markers, we conducted a randomized, three-campaign crossover design study with 12 healthy, moderately fit male subjects (age 34+/-8 y, body mass [BM] 70 +/- 8 kg). All study campaigns consisted of a 7-d ambulatory period, 21days of -6 deg. head-down tilt bed rest (HDBR), and a 6-d recovery period. Diet was standardized and identical across phases. In the control (CON) campaign, subjects received no supplement or RVE. In the intervention campaigns, subjects received either RVE alone or combined with WP and KHCO3 (NEX). WP was applied in 3 doses per day of 0.6 g WP/kg BM together with 6 doses of 15 mmol KHCO3 per day. Eleven subjects completed the RVE and CON campaign, 8 subjects completed all three campaigns. On day 21 of HDBR excretion of the bone resorption marker C-telopeptide (CTX) was 80+/-28% (p<0.001) higher than baseline, serum calcium concentrations increased by 12 +/- 29% (p<0.001) and serum osteocalcin concentrations decreased by 6+/-12% (p=0.001). Urinary CTX excretion was 11+/- 25% (p=0.02) lower on day 21 of HDBR in the RVE- and tended to decrease by 3+/- 22% (p=0.06) in the NEX campaign compared to CON. Urinary calcium excretion was higher on day 21 in HDBR in the RVE and NEX (24+/- 43% p=0.01; 25+/- 37% p=0.03) compared to the CON campaign. We conclude that combination of RVE with WP/KHCO3 was not

  6. Mean 24-hours sympathetic nervous system activity decreases during head-down tilted bed rest but not during microgravity

    NASA Astrophysics Data System (ADS)

    Christensen, Nj; Heer, M.; Ivanova, K.; Norsk, P.

    Sympathetic nervous system activity is closely related to gravitational stress in ground based experiments. Thus a high activity is present in the standing-up position and a very low activity is observed during acute head-out water immersion. Adjustments in sympathetic activity are necessary to maintain a constant blood pressure during variations in venous return. Head-down tilted bed rest is applied as a model to simulate changes observed during microgravity. The aim of the present study was to test the hypothesis that mean 24-hours sympathetic activity was low and similar during space flight and in ground based observation obtained during long-term head-down tilted bed rest. Forearm venous plasma noradrenaline was measured by a radioenzymatic technique as an index of muscle sympathetic activity and thrombocyte noradrenaline and adrenaline were measured as indices of mean 24-hours sympathoadrenal activity. Previous results have indicated that thrombocyte noradrenaline level has a half-time of 2 days. Thus to reflect sympathetic activity during a specific experiment the study period must last for at least 6 days and a sample must be obtained within 12 hours after the experiment has ended. Ten normal healthy subjects were studied before and during a 14 days head-down tilted bed rest as well as during an ambulatory study period of a similar length. The whole experiment was repeated while the subjects were on a low calorie diet. Thrombocyte noradrenaline levels were studied in 4 cosmonauts before and within 12 hours after landing after more than 7 days in flight. Thrombocyte noradrenaline decreased markedly during the head-down tilted bed rest (p<0.001), whereas there were no significant changes in the ambulatory study. Plasma noradrenaline decreased in the adaptation period but not during the intervention. During microgravity thrombocyte noradrenaline increased in four cosmonauts and the percentage changes were significantly different in cosmonauts and in subjects

  7. National Athletic Trainers' Association Position Statement: Head-Down Contact and Spearing in Tackle Football

    PubMed Central

    Heck, Jonathan F.; Clarke, Kenneth S.; Peterson, Thomas R.; Torg, Joseph S.; Weis, Michael P.

    2004-01-01

    Objective: To present recommendations that decrease the risk of cervical spine fractures and dislocations in football players. Background: Axial loading of the cervical spine resulting from head-down contact is the primary cause of spinal cord injuries. Keeping the head up and initiating contact with the shoulder or chest decreases the risk of these injuries. The 1976 rule changes resulted in a dramatic decrease in catastrophic cervical spine injuries. However, the helmet-contact rules are rarely enforced and head-down contact still occurs frequently. Our recommendations are directed toward decreasing the incidence of head-down contact. Recommendations: Educate players, coaches, and officials that unintentional and intentional head-down contact can result in catastrophic injuries. Increase the time tacklers, ball carriers, and blockers spend practicing correct contact techniques. Improve the enforcement and understanding of the existing helmet-contact penalties. PMID:15085218

  8. An evaluation of flight path formats head-up and head-down

    NASA Technical Reports Server (NTRS)

    Sexton, George A.; Moody, Laura E.; Evans, Joanne; Williams, Kenneth E.

    1988-01-01

    Flight path primary flight display formats were incorporated on head-up and head-down electronic displays and integrated into an Advanced Concepts Flight Simulator. Objective and subjective data were collected while ten airline pilots evaluated the formats by flying an approach and landing task under various ceiling, visibility and wind conditions. Deviations from referenced/commanded airspeed, horizontal track, vertical track and touchdown point were smaller using the head-up display (HUD) format than the head-down display (HDD) format, but not significantly smaller. Subjectively, the pilots overwhelmingly preferred (1) flight path formats over attitude formats used in current aircraft, and (2) the head-up presentation over the head-down, primarily because it eliminated the head-down to head-up transition during low visibility landing approaches. This report describes the simulator, the flight displays, the format evaluation, and the results of the objective and subjective data.

  9. Periodic upright posture negates the suppression of neuroendocrine response to head down bedrest

    NASA Technical Reports Server (NTRS)

    Wade, C. E.; Vernikos, J.; Evans, J.; Ohara, D.

    1992-01-01

    Head down bedrest (HDT) decreases plasma neurohormone levels, attaining a nadir within four hours. The present study evaluates the effect of periodic standing or exercises (+G(z)) on this acute suppression of plasma neurohormones. Methods: Nine male subjects (mean plus or minus SE age 37 plus or minus 2 yr; height 182 plus or minus 2 cm; weight 83 plus or minus 3 kg) were admitted to the Human Research Facility on three occasions separated by one month. Subjects were assigned to head down tilt (minus 6 degrees) or 15-minutes of standing or moderate exercise at the end of each hour. Initially during an ambulatory period, subjects were placed in a supine position for 45-min and a control blood sample obtained. The next day following 4 hours of HDT with or without standing or exercise a blood sample was taken 45-min (3 3/4 hours into HDT) after the preceding stand or exercise. Blood was withdrawn and all plasma samples frozen for determination of neurohormone levels within the same assay. Plasma aldosterone, Plasma Renin Activity (PRA) vasopressin (AVP) and cortisol levels were measured by radioimmunoassay. Norepinephrine (NE) and epinephrine (E) levels were measured by electrochemical detection following HPLC. Values were compared by ANOVA, P less than 0.05. Results: Control levels following 45-min supine were not different between treatments. HDT suppressed plasma aldosterone (13.9 plus or minus 3.7 to 6.6 plus or minus 0.7 ng/dl) and NE levels (299 plus or minus 35 to 217 plus or minus 23 pg/dl), E (69 plus or minus 15 to 65 plus or minus 21 pg/ml), and PRA (0.64 plus or minus 0.13 to 0.58 plus or minus 0.17 ngAl/m/hr) were not significantly altered. Standing or exercise negated the decrease in aldosterone and NE levels due to HDT. Conclusions: Periodic upright posture (+G(z)) with or without exercise for 15-min out of each hour negates the acute suppression of aldosterone and NE associated with HDT.

  10. Influence of head-down and lateral decubitus neck flexion on heart rate variability.

    PubMed

    Lee, C M; Wood, R H; Welsch, M A

    2001-01-01

    The purpose of this study was to examine the response of heart rate variability (HRV), a noninvasive index of autonomic control, to head-down neck flexion (HDNF), which engages both otoliths and neck muscle afferents, and to lateral decubitus neck flexion (LNF), in which neck afferents are activated, whereas otolith afferent input is not. HRV and forearm blood flow were evaluated in participants lying prone, during HDNF, lying in the lateral decubitus position, and during LNF. Compared with the prone position, HDNF resulted in lower high-frequency (46.9 +/- 7.1 vs. 62.3 +/- 6.2) and higher low-frequency (53.1 +/- 7.1 vs. 37.7 +/- 6.2) power, expressed as normalized units, along with higher low-frequency-to-high-frequency ratio (1.65 +/- 0.3 vs. 0.78 +/- 0.2), whereas LNF resulted in no alterations in HRV indexes. Furthermore, there were no significant differences in forearm blood flow or vascular resistance among any of the positions. Our data suggest that otolith organs influence autonomic modulation of the heart, supporting previous studies reporting that HDNF elicits increased sympathetic outflow. These data further suggest that HDNF results in a parasympathetic withdrawal from the heart in addition to sympathetic activation. PMID:11133902

  11. Prolonged head-down tilt exposure reduces maximal cutaneous vasodilator and sweating capacity in humans

    NASA Technical Reports Server (NTRS)

    Crandall, C. G.; Shibasaki, M.; Wilson, T. E.; Cui, J.; Levine, B. D.

    2003-01-01

    Cutaneous vasodilation and sweat rate are reduced during a thermal challenge after simulated and actual microgravity exposure. The effects of microgravity exposure on cutaneous vasodilator capacity and on sweat gland function are unknown. The purpose of this study was to test the hypothesis that simulated microgravity exposure, using the 6 degrees head-down tilt (HDT) bed rest model, reduces maximal forearm cutaneous vascular conductance (FVC) and sweat gland function and that exercise during HDT preserves these responses. To test these hypotheses, 20 subjects were exposed to 14 days of strict HDT bed rest. Twelve of those subjects exercised (supine cycle ergometry) at 75% of pre-bed rest heart rate maximum for 90 min/day throughout HDT bed rest. Before and after HDT bed rest, maximal FVC was measured, via plethysmography, by heating the entire forearm to 42 degrees C for 45 min. Sweat gland function was assessed by administering 1 x 10(-6) to 2 M acetylcholine (9 doses) via intradermal microdialysis while simultaneously monitoring sweat rate over the microdialysis membranes. In the nonexercise group, maximal FVC and maximal stimulated sweat rate were significantly reduced after HDT bed rest. In contrast, these responses were unchanged in the exercise group. These data suggest that 14 days of simulated microgravity exposure, using the HDT bed rest model, reduces cutaneous vasodilator and sweating capacity, whereas aerobic exercise training during HDT bed rest preserves these responses.

  12. Effect of intermittent standing and walking on physiological changes induced by head-down bed rest

    NASA Technical Reports Server (NTRS)

    Vernikos, J.; Ludwig, D. A.; Ertl, A. C.; Wade, C. E.; Keil, L.; OHara, D.

    1994-01-01

    Continuous exposure to gravity may not be necessary to prevent compromised physiological function resulting from exposure to microgravity. However, minimum gravity (G) exposure requirements, effectiveness of passive Gz versus activity in a G field, and optimal G stimulus amplitude, duration, and frequency are unknown. To partially address these questions, a 4-day, 6 degree head-down bed rest (HDBR) study (one ambulatory control day, 4 full HDBR days, one recovery day) was conducted. Nine males, 30-50 yr, were subjected to four different +1 Gz (head-foot) exposure protocols (periodic standing or controlled walking for 2 or 4 h/day in 15 min doses), plus a continuous HDBR (0 Gz) control. Standing 4 h completely prevented and standing 2 h partially prevented post-HDBR orthostatic intolerance. Both walking conditions (2 h and 4 h) attenuated the decrease in peak VO2 and prevented the increased urinary Ca2+ excretion associated with HDBR. Both 4 h conditions (standing and walking) attenuated plasma volume loss during HDBR. It was concluded that various physiological systems benefit differentially from passive +1 Gz or activity in +1 Gz and the duration (2 h vs. 4 h) of the stimulus may be an important moderating factor.

  13. Effects of Head-Down Bed Rest on the Executive Functions and Emotional Response

    PubMed Central

    Liu, Qing; Zhou, Renlai; Chen, Shanguang; Tan, Cheng

    2012-01-01

    Prolonged bed rest may cause changes in the autonomic nervous system that are related to cognition and emotion. This study adopted an emotional flanker task to evaluate the effect of 45 days -6° head-down bed rest (HDBR) on executive functioning in 16 healthy young men at each of six time points: the second-to-last day before the bed rest period, the eleventh, twentieth, thirty-second and fortieth day during the bed rest period, and the eighth day after the bed rest period. In addition, self-report inventories (Beck Anxiety Inventory, BAI; Beck Depression Inventory, BDI; Positive Affect and Negative Affect Scale, PANAS) were conducted to record emotional changes, and the participants’ galvanic skin response (GSR), heart rate (HR) and heart rate variability (HRV) were assessed as measures of physiological activity. The results showed that the participants’ reaction time on the flanker task increased significantly relative to their responses on the second-to-last day before the period of bed rest, their galvanic skin response weakened and their degrees of positive affect declined during the bed rest period. Our results provide some evidence for a detrimental effect of prolonged bed rest on executive functioning and positive affect. Whether this stems from a lack of aerobic physical activity and/or the effect of HDBR itself remains to be determined. PMID:23284916

  14. Cardiovascular Adaptations to Long Duration Head-Down Tilt Bed Rest

    NASA Technical Reports Server (NTRS)

    Platts, Steven H.; Martin, David S.; Perez, Sondar A.; Ribeiro, Christine; Stenger, Michael B.; Summers, Richard; Meck, Janice V.

    2008-01-01

    INTRODUCTION: Orthostatic hypotension is a serious risk for crewmembers returning from spaceflight. Numerous cardiovascular mechanisms have been proposed to account for this problem, including vascular and cardiac dysfunction, which we studied during bed rest. METHODS: Thirteen subjects were studied before and during bed rest. Statistical analysis was limited to the first 49-60 days of bed rest, and compared to pre-bed rest data. Ultrasound data were collected on vascular and cardiac structure and function. Tilt testing was conducted for 30 minutes or until presyncopal symptoms intervened. RESULTS: Plasma volume was significantly reduced by day 7 of bed rest. Flow-mediated dilation in the leg was significantly increased at bed rest day 49. Arterial responses to nitroglycerin differed in the arm and leg, but did not change as a result of bed rest. Intimal-medial thickness markedly decreased at bed rest days 21, 35 and 49. Several cardiac functional parameters including isovolumic relaxation time, ejection time and myocardial performance index were significantly increased (indicating a decrease in cardiac function) during bed rest. There was a trend for decreased orthostatic tolerance following 60 days of bed rest. DISCUSSION: These data suggest that 6 head-down tilt bed rest alters cardiovascular structure and function in a pattern similar to short duration spaceflight. Additionally, the vascular alterations are primarily seen in the lower body, while vessels of the upper body are unaffected. KEY WORDS: spaceflight, orthostatic intolerance, hypotension, fluid-shift, plasma volume

  15. Changes in the Diurnal Rhythms during a 45-Day Head-Down Bed Rest

    PubMed Central

    Liang, Xiaodi; Zhang, Lin; Wan, Yufeng; Yu, Xinyang; Guo, Yiming; Chen, Xiaoping; Tan, Cheng; Huang, Tianle; Shen, Hanjie; Chen, Xianyun; Li, Hongying; Lv, Ke; Sun, Fei; Chen, Shanguang; Guo, Jinhu

    2012-01-01

    In spaceflight human circadian rhythms and sleep patterns are likely subject to change, which consequently disturbs human physiology, cognitive abilities and performance efficiency. However, the influence of microgravity on sleep and circadian clock as well as the underlying mechanisms remain largely unknown. Placing volunteers in a prone position, whereby their heads rest at an angle of −6° below horizontal, mimics the microgravity environment in orbital flight. Such positioning is termed head-down bed rest (HDBR). In this work, we analysed the influence of a 45-day HDBR on physiological diurnal rhythms. We examined urinary electrolyte and hormone excretion, and the results show a dramatic elevation of cortisol levels during HDBR and recovery. Increased diuresis, melatonin and testosterone were observed at certain periods during HDBR. In addition, we investigated the changes in urination and defecation frequencies and found that the rhythmicity of urinary frequency during lights-off during and after HDBR was higher than control. The grouped defecation frequency data exhibits rhythmicity before and during HDBR but not after HDBR. Together, these data demonstrate that HDBR can alter a number of physiological processes associated with diurnal rhythms. PMID:23110150

  16. Changes in the diurnal rhythms during a 45-day head-down bed rest.

    PubMed

    Liang, Xiaodi; Zhang, Lin; Wan, Yufeng; Yu, Xinyang; Guo, Yiming; Chen, Xiaoping; Tan, Cheng; Huang, Tianle; Shen, Hanjie; Chen, Xianyun; Li, Hongying; Lv, Ke; Sun, Fei; Chen, Shanguang; Guo, Jinhu

    2012-01-01

    In spaceflight human circadian rhythms and sleep patterns are likely subject to change, which consequently disturbs human physiology, cognitive abilities and performance efficiency. However, the influence of microgravity on sleep and circadian clock as well as the underlying mechanisms remain largely unknown. Placing volunteers in a prone position, whereby their heads rest at an angle of -6° below horizontal, mimics the microgravity environment in orbital flight. Such positioning is termed head-down bed rest (HDBR). In this work, we analysed the influence of a 45-day HDBR on physiological diurnal rhythms. We examined urinary electrolyte and hormone excretion, and the results show a dramatic elevation of cortisol levels during HDBR and recovery. Increased diuresis, melatonin and testosterone were observed at certain periods during HDBR. In addition, we investigated the changes in urination and defecation frequencies and found that the rhythmicity of urinary frequency during lights-off during and after HDBR was higher than control. The grouped defecation frequency data exhibits rhythmicity before and during HDBR but not after HDBR. Together, these data demonstrate that HDBR can alter a number of physiological processes associated with diurnal rhythms. PMID:23110150

  17. Effects of prolonged head-down bed rest on physiological responses to moderate hypoxia

    NASA Technical Reports Server (NTRS)

    Loeppky, J. A.; Roach, R. C.; Selland, M. A.; Scotto, P.; Greene, E. R.; Luft, U. C.

    1993-01-01

    To determine the effects of hypoxia on physiological responses to simulated zero-gravity cardiopulmonary and fluid balance measurements were made in 6 subjects before and during 5-degree head-down bed rest (HDBR) over 8 d at 10,678 ft and a second time at this altitude as controls (CON). The V-dot(O2)(max) increased by 9 percent after CON, but fell 3 percent after HDBR. This reduction in work capacity during HDBR could be accounted for by inactivity. The heart rate response to a head-up tilt was greatly enhanced following HDBR, while mean blood pressure was lower. No significant negative impact of HDBR was noted on the ability to acclimatize to hypoxia in terms of pulmonary mechanics, gas exchange, circulatory or mental function measurements. No evidence of pulmonary interstitial edema or congestion was noted during HDBR at the lower PIO2 and blood rheology properties were not negatively altered. Symptoms of altitude illness were more prevalent, but not marked, during HDBR and arterial blood gases and oxygenation were not seriously effected by simulated microgravity. Declines in base excess with altitude were similar in both conditions. The study demonstrated a minimal effect of HDBR on the ability to adjust to this level of hypoxia.

  18. Aerodynamic characteristics at Mach 6 of a hypersonic research airplane concept having a 70 deg swept delta wing

    NASA Technical Reports Server (NTRS)

    Clark, L. E.; Richie, C. B.

    1977-01-01

    The hypersonic aerodynamic characteristics of an air-launched, delta-wing research aircraft concept were investigated at Mach 6. The effect of various components such as nose shape, wing camber, wing location, center vertical tail, wing tip fins, forward delta wing, engine nacelle, and speed brakes was also studied. Tests were conducted with a 0.021 scale model at a Reynolds number, based on model length, of 10.5 million and over an angel of attack range from -4 deg to 20 deg. Results show that most configurations with a center vertical tail have static longitudinal stability at trim, static directional stability at angles of attack up to 12 deg, and static lateral stability throughout the angle of attack range. Configurations with wing tip fins generally have static longitudinal stability at trim, have lateral stability at angles of attack above 8 deg, and are directionally unstable over the angle of attack range.

  19. Acute effects of head-down tilt and hypoxia on modulators of fluid homeostasis

    NASA Technical Reports Server (NTRS)

    Whitson, P. A.; Cintron, N. M.; Pietrzyk, R. A.; Scotto, P.; Loeppky, J. A.

    1994-01-01

    In an effort to understand the interaction between acute postural fluid shifts and hypoxia on hormonal regulation of fluid homeostasis, the authors measured the responses to head-down tilt with and without acute exposure to normobaric hypoxia. Plasma atrial natriuretic peptide (ANP), cyclic guanosine monophosphate (cGMP), cyclic adenosine monophosphate (cAMP), plasma aldosterone (ALD), and plasma renin activity (PRA) were measured in six healthy male volunteers who were exposed to a head-down tilt protocol during normoxia and hypoxia. The tilt protocol consisted of a 17 degrees head-up phase (30 minutes), a 28 degrees head-down phase (1 hour), and a 17 degrees head-up recovery period (2 hours, with the last hour normoxic in both experiments). Altitude equivalent to 14,828 ft was simulated by having the subjects breathe an inspired gas mixture with 13.9% oxygen. The results indicate that the postural fluid redistribution associated with a 60-minute head-down tilt induces the release of ANP and cGMP during both hypoxia and normoxia. Hypoxia increased cGMP, cAMP, ALD, and PRA throughout the protocol and significantly potentiated the increase in cGMP during head-down tilt. Hypoxia had no overall effect on the release of ANP, but appeared to attenuate the increase with head-down tilt. This study describes the acute effects of hypoxia on the endocrine response during fluid redistribution and suggests that the magnitude, but not the direction, of these changes with posture is affected by hypoxia.

  20. Behavioral and Psychological Issues in Long Duration Head-down Bed Rest

    NASA Technical Reports Server (NTRS)

    Seaton, Kimberly A.; Bowie, Kendra; Sipes, Walter A.

    2008-01-01

    Behavioral health services, similar to those offered to the U.S. astronauts who complete six-month missions on board the International Space Station, were provided to 13 long-duration head-down bed rest participants. Issues in psychological screening, selection, and support are discussed as they relate to other isolated and confined environments. Psychological services offered to participants are described, and challenges in subject selection and retention are discussed. Psychological support and training provided to both subjects and study personnel have successfully improved the well-being of study participants. Behavioral health services are indispensable to long-duration head-down tilt bed rest studies.

  1. Effect on the cardiac function of repeated LBNP during a 1-month head down tilt

    NASA Astrophysics Data System (ADS)

    Arbeille, Ph.; Lebouard, D.; Massabuau, M.; Pottier, J. M.; Patat, F.; Pourcelot, L.; Guell, A.

    Cardiovascular assessment by ultrasound methods was performed during two long duration (1 month) Head Down Tilt (HDT) on 6 healthy volunteers. On a first 1 month HDT session, 3 of the 6 subjects (A, B, C) had daily several lower body negative pressure tests (LBNP), whereas the 3 subjects remaining (D, E, F) rested without LBNP. On a second 1 month HDT session subjects D, E, and F had daily LBNP tests and the A, B and C subjects did not. The cardiac function was assessed by Echocardiography (B mode, TM mode). On all the "6 non LBNP" subjects the left ventricule diastolic volume (LVDV), the stroke volume (SV) and the cardiac output (CO) increase (+10%, -15%) after HDT then decrease and remain inferior (-5%, -5%) or equal to the basal value during the HDT. Immediately after the end of the HDT the heart rate (HR) increase (+10%, +30%) whereas the cardiac parameters decrease weakly (-5%, -10%) and normalize after 3 days of recovery. On the "6 LBNP" subjects the LVDV, SV and CO increase (+10%, +15%) after 1 h HDT as in the previous group then decrease but remain superior (+5%, +15%) or equal to the basal value. After the HDT session, the HR is markedly increased (+20%, +40%) the LVDV and SV decrease (-15%, -20%) whereas the CO increases or decreases depending on the amplitude of the HR variations. These parameters do not completely normalize after 3 days recovery. Repeated LBNP sessions have a significant effect on the cardiovascular function as it maintains all cardiac parameters above the basal value. The LBNP manoeuvre can be considered as an efficient countermeasure to prevent cardiac disadaptation induced by HDT position and probably microgravity.

  2. Wind-tunnel pressure data at Mach numbers from 1.6 to 4.63 for a series of bodies of revolution at angles of attack from -4 deg to 60 deg

    NASA Technical Reports Server (NTRS)

    Landrum, E. J.

    1977-01-01

    The tabulated results of wind tunnel pressure tests are presented without analysis. The data were obtained for a series of six bodies of revolution at Mach numbers of 1.6, 2.3, 2.96, and 4.63 for angles of attack from -4 deg. to 60 deg. The Reynolds number used for these tests was 6.6 x 6/million per meter.

  3. Wind-tunnel force and flow visualization data at Mach numbers from 1.6 to 4.63 for a series of bodies of revolution at angles of attack from minus 4 deg to 60 deg

    NASA Technical Reports Server (NTRS)

    Landrum, E. J.; Babb, C. D.

    1979-01-01

    Flow visualization and force data for a series of six bodies of revolution are presented without analysis. The data were obtained in the Langley Unitary Plan wind tunnel for angles of attack from -4 deg to 60 deg. The Reynolds number used for these tests was 6,600,000 per meter.

  4. Ocular Outcomes Evaluation in a 14-Day Head-Down Bed Rest Study

    PubMed Central

    Taibbi, Giovanni; Cromwell, Ronita L.; Zanello, Susana B.; Yarbough, Patrice O.; Ploutz-Snyder, Robert J.; Godley, Bernard F.; Vizzeri, Gianmarco

    2014-01-01

    Introduction We evaluated ocular outcomes in a 14-day head-down tilt (HDT) bed rest (BR) study designed to simulate the effects of microgravity on the human body. Methods Healthy subjects were selected using NASA standard screening procedures. Standardized NASA BR conditions were implemented (e.g., strict sleep-wake cycle, standardized diet, 24-hour-a-day BR, continuous video monitoring). Subjects maintained a 6° HDT position for 14 consecutive days. Weekly ophthalmological examinations were performed in the sitting (pre/post-BR) and HDT (in-bed phase) positions. Equivalency tests with optimal-alpha techniques evaluated pre/post-BR differences in best-corrected visual acuity (BCVA), spherical equivalent, intraocular pressure (IOP), Spectral-domain OCT retinal nerve fiber layer thickness (RNFLT), optic disc and macular parameters. Results 16 subjects (12 men and 4 women) were enrolled. Nearly all ocular outcomes were within our predefined clinically relevant thresholds following HDTBR, except near BCVA (pre/post-BR mean difference: −0.06 logMAR), spherical equivalent (−0.30 D), Tonopen XL IOP (+3.03 mmHg) and Spectralis OCT average (+1.14 μm), temporal-inferior (+1.58 μm) and nasal-inferior RNFLT (+3.48 μm). Modified Amsler grid, red dot test, confrontational visual field and color vision were within normal limits throughout. No changes were detected on stereoscopic color fundus photography. Discussion A few functional and structural changes were detected after 14-day HDTBR, notably an improved BCVA possibly due to learning effect and RNFL thickening without signs of optic disc edema. In general, 6° HDTBR determined a small non-progressive IOP elevation, which returned to baseline levels post-BR. Further studies with different BR duration and/or tilt angle are warranted to investigate microgravity-induced ophthalmological changes. PMID:25245897

  5. Lower Limb Venous Compliance is Different Between Men and Women Following 60 Days of Head-Down Bedrest but Is Not Associated with Venoconstriction Dysfunction

    NASA Technical Reports Server (NTRS)

    Westby, Christian M.; Lee, Stuart M. C.; Stenger, Michael B.; Platts, Steven H.

    2012-01-01

    Space flight-induced orthostatic intolerance (OI) is more prevalent in female (F) than male (M) astronauts. The mechanisms explaining the higher incidence of OI in F are unclear. We tested the hypothesis that venous compliance would be higher in F more than M following 6 deg head-down bed rest (BR) and would be associated with constrictor dysfunction. Using 2-D ultrasound, dorsal hand (DHV) and dorsal foot (DFV) vein compliances were determined in 24 subjects (10 F, 14 M; 35 +/- 1 yr) by measuring mean diameter response to increasing congestion pressure (0, 20, 30, and 40 mmHg) before and after 60 d of BR. Constrictor function was assessed by intravenous infusions of Ketorolac (KE; 1.5 ig/min) Phenylephrine (PE; 3160 ng/min), and L-NMMA (50 ig/min). The effects of BR between F vs. M and hand vs. foot were determined using mixed-effects linear regression. DFV but not DHV compliance changed in response to BR (p=0.012). Mean DFV increased significantly (0.903 mm to 1.191mm) in F but decreased in M (1.353 mm to 1.154 mm). DFV constrictor response was not different between sexes in response to BR (KE; p=0.647, PE; p=0.717, and L-NMMA; p=0.825). These BR data suggest that the higher incidence of OI in F astronauts may be related to increased lower limb venous compliance, contributing to blood pooling upon standing. Notably, changes to DFV compliance was not accompanied by impaired constrictor function.

  6. Left ventricular remodeling during and after 60 days of sedentary head-down bed rest.

    PubMed

    Westby, Christian M; Martin, David S; Lee, Stuart M C; Stenger, Michael B; Platts, Steven H

    2016-04-15

    Short periods of weightlessness are associated with reduced stroke volume and left ventricular (LV) mass that appear rapidly and are thought to be largely dependent on plasma volume. The magnitude of these cardiac adaptations are even greater after prolonged periods of simulated weightlessness, but the time course during and the recovery from bed rest has not been previously described. We collected serial measures of plasma volume (PV, carbon monoxide rebreathing) and LV structure and function [tissue Doppler imaging, three-dimensional (3-D) and 2-D echocardiography] before, during, and up to 2 wk after 60 days of 6° head down tilt bed rest (HDTBR) in seven healthy subjects (four men, three women). By 60 days of HDTBR, PV was markedly reduced (2.7 ± 0.3 vs. 2.3 ± 0.3 liters,P< 0.001). Resting measures of LV volume and mass were ∼15% (P< 0.001) and ∼14% lower (P< 0.001), respectively, compared with pre-HDTBR values. After 3 days of reambulation, both PV and LV volumes were not different than pre-HDTBR values. However, LV mass did not recover with normalization of PV and remained 12 ± 4% lower than pre-bed rest values (P< 0.001). As previously reported, decreased PV and LV volume precede and likely contribute to cardiac atrophy during prolonged LV unloading. Although PV and LV volume recover rapidly after HDTBR, there is no concomitant normalization of LV mass. These results demonstrate that reduced LV mass in response to prolonged simulated weightlessness is not a simple effect of tissue dehydration, but rather true LV muscle atrophy that persists well into recovery. PMID:26494448

  7. Effects of head-down-tilt bed rest on cerebral hemodynamics during orthostatic stress

    NASA Technical Reports Server (NTRS)

    Zhang, R.; Zuckerman, J. H.; Pawelczyk, J. A.; Levine, B. D.; Blomqvist, C. G. (Principal Investigator)

    1997-01-01

    Our aim was to determine whether the adaptation to simulated microgravity (microG) impairs regulation of cerebral blood flow (CBF) during orthostatic stress and contributes to orthostatic intolerance. Twelve healthy subjects (aged 24 +/- 5 yr) underwent 2 wk of -6 degrees head-down-tilt (HDT) bed rest to simulate hemodynamic changes that occur when humans are exposed to microG. CBF velocity in the middle cerebral artery (transcranial Doppler), blood pressure, cardiac output (acetylene rebreathing), and forearm blood flow were measured at each level of a ramped protocol of lower body negative pressure (LBNP; -15, -30, and -40 mmHg x 5 min, -50 mmHg x 3 min, then -10 mmHg every 3 min to presyncope) before and after bed rest. Orthostatic tolerance was assessed by using the cumulative stress index (CSI; mmHg x minutes) for the LBNP protocol. After bed rest, each individual's orthostatic tolerance was reduced, with the group CSI decreased by 24% associated with greater decreases in cardiac output and greater increases in systemic vascular resistance at each level of LBNP. Before bed rest, mean CBF velocity decreased by 14, 10, and 45% at -40 mmHg, -50 mmHg, and maximal LBNP, respectively. After bed rest, mean velocity decreased by 16% at -30 mmHg and by 21, 35, and 39% at -40 mmHg, -50 mmHg, and maximal LBNP, respectively. Compared with pre-bed rest, post-bed-rest mean velocity was less by 11, 10, and 21% at -30, -40, and -50 mmHg, respectively. However, there was no significant difference at maximal LBNP. We conclude that cerebral autoregulation during orthostatic stress is impaired by adaptation to simulated microG as evidenced by an earlier and greater fall in CBF velocity during LBNP. We speculate that impairment of cerebral autoregulation may contribute to the reduced orthostatic tolerance after bed rest.

  8. Bone metabolism and nutritional status during 30-day head-down-tilt bed rest

    PubMed Central

    Morgan, Jennifer L. L.; Zwart, Sara R.; Heer, Martina; Ploutz-Snyder, Robert; Ericson, Karen

    2012-01-01

    Bed rest studies provide an important tool for modeling physiological changes that occur during spaceflight. Markers of bone metabolism and nutritional status were evaluated in 12 subjects (8 men, 4 women; ages 25–49 yr) who participated in a 30-day −6° head-down-tilt diet-controlled bed rest study. Blood and urine samples were collected twice before, once a week during, and twice after bed rest. Data were analyzed using a mixed-effects linear regression with a priori contrasts comparing all days to the second week of the pre-bed rest acclimation period. During bed rest, all urinary markers of bone resorption increased ∼20% (P < 0.001), and serum parathyroid hormone decreased ∼25% (P < 0.001). Unlike longer (>60 days) bed rest studies, neither markers of oxidative damage nor iron status indexes changed over the 30 days of bed rest. Urinary oxalate excretion decreased ∼20% during bed rest (P < 0.001) and correlated inversely with urinary calcium (R = −0.18, P < 0.02). These data provide a broad overview of the biochemistry associated with short-duration bed rest studies and provide an impetus for using shorter studies to save time and costs wherever possible. For some effects related to bone biochemistry, short-duration bed rest will fulfill the scientific requirements to simulate spaceflight, but other effects (antioxidants/oxidative damage, iron status) do not manifest until subjects are in bed longer, in which case longer studies or other analogs may be needed. Regardless, maximizing research funding and opportunities will be critical to enable the next steps in space exploration. PMID:22995395

  9. Bone metabolism and nutritional status during 30-day head-down-tilt bed rest.

    PubMed

    Morgan, Jennifer L L; Zwart, Sara R; Heer, Martina; Ploutz-Snyder, Robert; Ericson, Karen; Smith, Scott M

    2012-11-01

    Bed rest studies provide an important tool for modeling physiological changes that occur during spaceflight. Markers of bone metabolism and nutritional status were evaluated in 12 subjects (8 men, 4 women; ages 25-49 yr) who participated in a 30-day -6° head-down-tilt diet-controlled bed rest study. Blood and urine samples were collected twice before, once a week during, and twice after bed rest. Data were analyzed using a mixed-effects linear regression with a priori contrasts comparing all days to the second week of the pre-bed rest acclimation period. During bed rest, all urinary markers of bone resorption increased ~20% (P < 0.001), and serum parathyroid hormone decreased ~25% (P < 0.001). Unlike longer (>60 days) bed rest studies, neither markers of oxidative damage nor iron status indexes changed over the 30 days of bed rest. Urinary oxalate excretion decreased ~20% during bed rest (P < 0.001) and correlated inversely with urinary calcium (R = -0.18, P < 0.02). These data provide a broad overview of the biochemistry associated with short-duration bed rest studies and provide an impetus for using shorter studies to save time and costs wherever possible. For some effects related to bone biochemistry, short-duration bed rest will fulfill the scientific requirements to simulate spaceflight, but other effects (antioxidants/oxidative damage, iron status) do not manifest until subjects are in bed longer, in which case longer studies or other analogs may be needed. Regardless, maximizing research funding and opportunities will be critical to enable the next steps in space exploration. PMID:22995395

  10. Long Duration Head-Down Tilt Bed Rest Studies: Safety Considerations Regarding Vision Health

    NASA Technical Reports Server (NTRS)

    Cromwell, Ronita L.; Zanello, S. B.; Yarbough, P. O.; Ploutz-Snyder, Robert; Taibbi, G.; Vizzeri, G.

    2012-01-01

    Visual symptoms reported in astronauts returning from long duration missions in low Earth orbit, including hyperopic shift, choroidal folds, globe flattening and papilledema, are thought to be related to fluid shifts within the body due to microgravity exposure. Because of this possible relation to fluid shifts, safety considerations have been raised regarding the ocular health of head-down tilt (HDT) bed rest subjects. HDT is a widely used ground ]based analog that simulates physiological changes of spaceflight, including fluid shifts. Thus, vision monitoring has been performed in bed rest subjects in order to evaluate the safety of HDT with respect to vision health. Here we report ocular outcomes in 9 healthy subjects (age range: 27-48 years; Male/Female ratio: 8/1) completing bed rest Campaign 11, an integrated, multidisciplinary 70-day 6 degrees HDT bed rest study. Vision examinations were performed on a weekly basis, and consisted of office-based (2 pre- and 2 post-bed rest) and in-bed testing. The experimental design was a repeated measures design, with measurements for both eyes taken for each subject at each planned time point. Findings for the following tests were all reported as normal in each testing session for every subject: modified Amsler grid, red dot test, confrontational visual fields, color vision and fundus photography. Overall, no statistically significant differences were observed for any of the measures, except for both near and far visual acuity, which increased during the course of the study. This difference is not considered clinically relevant as may result from the effect of learning. Intraocular pressure results suggest a small increase at the beginning of the bed rest phase (p=0.059) and lesser increase at post-bed rest with respect to baseline (p=0.046). These preliminary results provide the basis for further analyses that will include correlations between intraocular pressure change pre- and post-bed rest, and optical coherence

  11. Effects of 30-Day Head-Down Bed Rest on Ocular Structures and Visual Function in a Healthy Subject

    PubMed Central

    Taibbi, Giovanni; Kaplowitz, Kevin; Cromwell, Ronita L.; Godley, Bernard F.; Zanello, Susana B.; Vizzeri, Gianmarco

    2013-01-01

    Introduction We report ocular changes occurring in a healthy human subject enrolled in a bed rest (BR) study designed to replicate the effects of a low-gravity environment. Case report A 25-year-old Caucasian male spent 30 consecutive days in a 6° head-down-tilt position at the NASA Flight Analogs Research Unit. Comprehensive ophthalmologic exams, optic disc stereo-photography, Standard Automated Perimetry (SAP) and optic disc Spectralis OCT scans were performed at baseline, immediately post-BR (BR+0) and 6 months post-BR. Main outcome measures: changes in best-corrected visual acuity, intraocular pressure (IOP), cycloplegic refraction, SAP and Spectralis OCT measures. At BR+0 IOP was 11 and 10 mmHg in the right (OD) and left eye (OS), respectively (a bilateral 4 mmHg decrease compared to baseline); SAP documented a possible bilateral symmetrical inferior scotoma; Spectralis OCT showed an average 19.4 μm (+5.2%) increase in peripapillary retinal thickness, and an average 0.03 mm3 (+5.0%) increase in peripapillary retinal volume bilaterally. However, there were no clinically detectable signs of optic disc edema. 6 months post-BR, IOP was 13 and 14 mmHg in OD and OS, respectively, and the scotoma had resolved. Spectralis OCT measurements matched the ones recorded at baseline. Discussion In this subject, a reduction in IOP associated with subtle structural and functional changes compared to baseline were documented after prolonged head-down BR. These changes may be related to cephalad fluid shifts in response to tilt. Further studies should clarify whether decreased translaminar pressure (i.e., the difference between IOP and intracranial pressure) may be responsible for these findings. PMID:23447853

  12. Fluid compartment and renal function alterations in the rat during 7 and 14 day head down tilt

    NASA Technical Reports Server (NTRS)

    Tucker, Bryan J.

    1991-01-01

    Exposure to conditions of microgravity for any extended duration can modify the distribution of fluid within the vascular and interstitial spaces, and eventually intracellular volume. Whether the redistribution of fluid and resetting of volume homeostasis mechanisms is appropriate for the long term environmental requirements of the body in microgravity remains to be fully defined. The event that initiates the change in fluid volume homeostasis is the cephalad movement of fluid which potentially triggers volume sensors and stretch receptors (atrial stretch with the resulting release of atrial natriuretic peptide) and suppresses adrenergic activity via the carotid and aortic arch baroreceptors. All these events act in concert to reset blood and interstitial volume to new levels, which in turn modify the renin-angiotensin system. All these factors have an influence on the kidney, the end organ for fluid volume control. How the fluid compartment volume changes interrelate with alterations in renal functions under conditions of simulated microgravity is the focus of the present investigation which utilizes 25-30 deg head-down tilt in the rat.

  13. Analysis of head-down tilt as an analog of weightlessness using a methematical simulation model

    NASA Technical Reports Server (NTRS)

    Leonard, J. I.

    1984-01-01

    Antiorthostasis or head down tilt of a moderate degree was used as a ground based analog of weightless space flight to study headward fluid shifts, decreased plasma volume, orthostatic intolerance and muscular skeletal degradation. A mathematical model was used to help interpret these observations. The model proved most valuable for these studies was originally developed as a description of the major circulatory, fluid and electrolyte control systems. Two different experimental studies are employed to validate the model. The first is a 24 hour head down tilt study and the second is a 7 day head down bed rest study. The major issues addressed include the reduction in plasma volume, the dynamic changes of venous pressure and cardiac output, the extent of central hypervolemia during long term zero g exposure, the existence of an early diuresis, the mechanisms which alter the renal regulating hormones during the short term and long term periods, the significance of potassium loss on other zero g responses, and the role of transcapillary filtration in adjusting fluid shifts. The use of mathematical models as an interpretive and analysis technique for experimental research for space life science is illustrated.

  14. [Positional asphyxia--death in a head-down position after falling down stairs].

    PubMed

    Doberentz, Elke; Madea, Burkhard

    2012-01-01

    The discovery of a body in an unusual position such as a head-down position requires thorough investigation. In this article, such a death is reported. A 64-year-old man was found in a head-down position at the bottom of a narrow staircase after obviously falling down the stairs. His head was wedged between the last step and a closed sliding door. Autopsy revealed craniofacial blunt force injuries, a non-dislocated fracture of the 4th cervical vertebral body (with intact ligaments of the spine and cervical cord) and massive cerebral and pulmonary oedema. Although the heart was significantly enlarged (610 g), the coronary arteries showed only minor arteriosclerotic changes. The alcohol concentration measured was 2.06 per mil in blood and 2.67 per mil in urine. The alcohol intoxication increased the risk to fall and together with the trauma of the cervical spine made it impossible for the man to free himself so that he ultimately died in a head-down position. PMID:23136702

  15. Ocular Outcomes Comparison Between 14- and 70-Day Head-Down-Tilt Bed Rest

    PubMed Central

    Taibbi, Giovanni; Cromwell, Ronita L.; Zanello, Susana B.; Yarbough, Patrice O.; Ploutz-Snyder, Robert J.; Godley, Bernard F.; Vizzeri, Gianmarco

    2016-01-01

    Purpose To compare ocular outcomes in healthy subjects undergoing 14- and/or 70-day head-down-tilt (HDT) bed rest (BR). Methods Participants were selected by using NASA standard screening procedures. Standardized NASA BR conditions were implemented. Subjects maintained a 6° HDT position for 14 and/or 70 consecutive days. Weekly ophthalmologic examinations were performed in the sitting (pre/post-BR only) and HDT positions. Mixed-effects linear models compared pre- and post-HDT BR observations between 14- and 70-day HDT BR in best-corrected visual acuity, spherical equivalent, intraocular pressure (IOP), Spectralis OCT retinal nerve fiber layer thickness, peripapillary and macular retinal thicknesses. Results Sixteen and six subjects completed the 14- and 70-day HDT BR studies, respectively. The magnitude of HDT BR–induced changes was not significantly different between the two studies for all outcomes, except the superior (mean pre/post difference of 14- vs. 70-day HDT BR: +4.69 μm versus +11.50 μm), nasal (+4.63 μm versus +11.46 μm), and inferior (+4.34 μm versus +10.08 μm) peripapillary retinal thickness. A +1.42 mm Hg and a +1.79 mm Hg iCare IOP increase from baseline occurred during 14- and 70-day HDT BR, respectively. Modified Amsler grid, red dot test, confrontational visual field, color vision, and stereoscopic fundus photography were unremarkable. Conclusions Seventy-day HDT BR induced greater peripapillary retinal thickening than 14-day HDT BR, suggesting that time may affect the amount of optic disc swelling. Spectralis OCT detected retinal nerve fiber layer thickening post BR, without clinical signs of optic disc edema. A small IOP increase during BR subsided post HDT BR. Such changes may have resulted from BR-induced cephalad fluids shift. The HDT BR duration may be critical for replicating microgravity-related ophthalmologic changes observed in astronauts on ≥6-month spaceflights. PMID:26868753

  16. Sympathetic and vascular responses to head-down neck flexion in humans.

    PubMed

    Shortt, T L; Ray, C A

    1997-04-01

    Animal studies have demonstrated increases in sympathetic nerve outflow with vestibular stimulation. The purpose of the present study was to determine whether vestibulosympathetic reflexes are engaged in humans. Muscle sympathetic nerve activity (MSNA), heart rate, arterial pressure, calf blood flow (CBF), and calculated calf vascular resistance (CVR; mean arterial pressure/CBF) were determined during 10 min of baseline (laying prone with chin supported) and 10 min of head-down neck flexion (HDNF). MSNA responses were measured in nine subjects, and calf vascular responses were determined in seven of these subjects. Heart rate increased during the first minute of HDNF (71 +/- 2 to 76 +/- 3 beats/min; P < 0.05) and remained slightly elevated (71 +/- 2 to 74 +/- 3 beats/min; P < 0.05) for the duration of HDNF. Diastolic and mean arterial pressures also increased slightly with HDNF (80 +/- 3 to 82 +/- 3 and 96 +/- 3 to 98 +/- 3 mmHg, respectively; P < 0.05). Systolic arterial pressure did not change significantly during HDNF. CBF decreased 14% (4.63 +/- 0.78 to 3.97 +/- 0.60 ml x min(-1) x 100 ml(-1); P < 0.05), and CVR increased 12% (24.0 +/- 4.3 to 27.4 +/- 4.7 units; P < 0.05) during HDNF. These changes corresponded with significant increases in MSNA during HDNF. MSNA, expressed as burst frequency, increased from 14 +/- 2 to 20 +/- 2 bursts/min (P < 0.05) and increased 63 +/- 23% (P < 0.05) when expressed as the percent change in total activity. All variables returned to baseline during recovery. Thoracic impedance measured in five subjects did not change during HDNF (19.6 +/- 1.2 to 19.7 +/- 1.5 omega), suggesting no major change in central blood volume. The results indicate that HDNF elicits increases in CVR that are mediated by the augmentation of MSNA. Arterial pressure responses and thoracic impedance data suggest that high and low pressure baroreflexes were not the mechanism for sympathetic activation. The immediate increase in MSNA with HDNF suggests a role

  17. System requirements for head down and helmet mounted displays in the military avionics environment

    SciTech Connect

    Flynn, M.F.; Kalmanash, M.; Sethna, V.

    1996-12-31

    The introduction of flat panel display technologies into the military avionics cockpit is a challenging proposition, due to the very difficult system level requirements which must be met. These relate to environmental extremes (temperature and vibrational), sever ambient lighting conditions (10,000 fL to nighttime viewing), night vision system compatibility, and wide viewing angle. At the same time, the display system must be packaged in minimal space and use minimal power. The authors will present details on the display system requirements for both head down and helmet mounted systems, as well as information on how these challenges may be overcome.

  18. Head-up and head-down displays integration in automobiles

    NASA Astrophysics Data System (ADS)

    Betancur, J. Alejandro; Osorio-Gómez, Gilberto; Agudelo, J. David

    2014-06-01

    In automotive industry, the dashboard has been ergonomically developed in order to keep the driver focused on the horizon while driving, but the possibility to access external electronic devices constraints the driver to turn away his face, generating dangerous situations in spite of the short periods of time. Therefore, this work explores the integration of Head-Up Displays and Head-Down Displays in automobiles, proposing configurations that give to drivers the facility to driving focused. In this way, some of the main ergonomic comments about those configurations are proposed; and also, some technical comments regarding the implemented arrangements are given.

  19. Hormonal and metabolic responses of hypophysectomized rats with head-down suspension

    NASA Technical Reports Server (NTRS)

    Tipton, C. M.; Grindeland, R. E.; Woodman, C. R.; Gosselink, K.; Linderman, J. K.; Mukku, V. R.; Gooselink, K.

    1994-01-01

    The primary purpose of this investigation was to secure select anatomical and physiological measurements from hypophysectomized rats and their sham-operated control to determine how various endocrine influences could be modified by conditions of simulated microgravity. The focal point of the study was the exercise responses after head-down suspension; however, we were also interested in obtaining insights on nonexercise-related mechanisms. Since more details and information concerning this study will be published elsewhere, we will highlight those findings which warrant further research.

  20. Effect on real-world depth perception from exposure to heads-down stereoscopic flight displays

    NASA Technical Reports Server (NTRS)

    Busquets, Anthony M.; Williams, Steven P.; Parrish, Russell V.

    1990-01-01

    A stereoacuity test was used as part of the experimental protocol of a study in which eight transport pilots flew repeated simulated landing approaches using both stereo and nonstereo three-dimensional heads-down 'pathway in the sky' displays. At the decisionmaking crux of each approach, the pilots transitioned to a stereoacuity test employing real objects rather than a two-dimensional target apparatus. A statistical analysis of stereoacuity measures which compared a controlled condition of no exposure to any electronic flight display with the transition data from nonstereo and stereopsis displays indicated no significant differences for any of the conditions.

  1. Analysis of Arterial Mechanics During Head-down Tilt Bed Rest

    NASA Technical Reports Server (NTRS)

    Elliot, Morgan; Martin, David S.; Westby, Christian M.; Stenger, Michael B.; Platts, Steve

    2014-01-01

    Arterial health may be affected by microgravity or ground based analogs of spaceflight, as shown by an increase in thoracic aorta stiffness1. Head-down tilt bed rest (HDTBR) is often used as a ground-based simulation of spaceflight because it induces physiological changes similar to those that occur in space2, 3. This abstract details an analysis of arterial stiffness (a subclinical measure of atherosclerosis), the distensibility coefficient (DC), and the pressure-strain elastic modulus (PSE) of the arterial walls during HDTBR. This project may help determine how spaceflight differentially affects arterial function in the upper vs. lower body.

  2. Bone Resorption Increases as Early as the Second Day in Head- Down Bed Rest

    NASA Astrophysics Data System (ADS)

    Heer, M.; Kamps, N.; Mika, C.; Boese, A.; Gerzer, R.

    Long-term bed rest and space mission studies have shown that immobilization as well as microgravity induce increased bone resorption while bone formation tends to decrease. In order to analyze the kinetics of short-term changes in bone turnover we studied in a randomized, strictly controlled crossover design the effects of 6 days 6° head-down tilt bed rest (HDT) in 8 male healthy subjects (mean body weight (BW): 70.1 +/- 1.88 kg; mean age: 25.5 +/- 1.04 years) in our metabolic ward. Two days before arriving in the metabolic ward the subjects started with a diet consisting of an energy content of 10 MJ/d, 2000 mg Calcium/d, 400 i.U. Vitamin D, 200 mEq Na+ and 50 ml water/kg BW/d. The diet was continued in the metabolic ward. The metabolic ward period (11days) was divided into 3 parts: 4 ambulatory days, 6 days either HDT or control and 1 recovery day. Continuous urine collection started on the first day in the metabolic ward to analyze calcium excretion and bone resorption markers, namely C-telopeptide (CTX) and N-telopeptide (NTX). On the 2nd ambulatory day in the metabolic ward and on the 5th day in HDT or control blood was drawn to analyze serum calcium, parathyroid hormone, and bone formation markers (bone Alkaline Phosphatase (bAP), Procollagen-I-Propeptide (P-I-CP). Both study phases were identical with respect to environmental conditions, study protocol and diet. Urinary calcium excretion was as early as the first day in immobilization increased (p<0.01). CTX- and NTX-excretion stayed unchanged the first 24 hours in HDT compared to the control. But, already on the 2nd day of immobilization both bone resorption markers significantly increased. NTX-excretion was increased by 28.7 +/- 14.0% (p<0.05), while CTX-excretion rose by 17.8 +/- 8.3% (p<0.01). Both, the CTX- excretion as well as the calcium excretion keep the significantly higher level during the HDT period, and even continued through the first day of recovery. However, NTX excretion, descended from day

  3. Terrain Portrayal for Synthetic Vision Systems Head-Down Displays Evaluation Results: Compilation of Pilot Transcripts

    NASA Technical Reports Server (NTRS)

    Hughes, Monica F.; Glaab, Louis J.

    2007-01-01

    The Terrain Portrayal for Head-Down Displays (TP-HDD) simulation experiment addressed multiple objectives involving twelve display concepts (two baseline concepts without terrain and ten synthetic vision system (SVS) variations), four evaluation maneuvers (two en route and one approach maneuver, plus a rare-event scenario), and three pilot group classifications. The TP-HDD SVS simulation was conducted in the NASA Langley Research Center's (LaRC's) General Aviation WorkStation (GAWS) facility. The results from this simulation establish the relationship between terrain portrayal fidelity and pilot situation awareness, workload, stress, and performance and are published in the NASA TP entitled Terrain Portrayal for Synthetic Vision Systems Head-Down Displays Evaluation Results. This is a collection of pilot comments during each run of the TP-HDD simulation experiment. These comments are not the full transcripts, but a condensed version where only the salient remarks that applied to the scenario, the maneuver, or the actual research itself were compiled.

  4. 60 Days of Head-down Bedrest Differentially Alters Venous Function in Lower and Upper Body Between Healthy Men and Women

    NASA Technical Reports Server (NTRS)

    Westby, Christian M.; Platts, Steven H.

    2010-01-01

    The incidence of orthostatic intolerance after space flight is disproportionally higher in female compared to male crewmembers (83% vs. 20%). Experimental and human data suggest that the loss of orthostatic tolerance is due, at least in part, to microgravity-induced changes in venous compliance and that these changes are specific to the lower body. It is unknown however, whether the changes in venous compliance are different between males and females after space flight, and whether this is related to the disparity in orthostatic intolerance between the sexes. Using 6deg head-down bed rest (BR) as a model of space flight, we tested the following hypotheses; 1) females, compared to males, would experience a greater increase in venous compliance in dorsal foot veins as an effect of BR and 2) no differences in venous compliance would be found in dorsal hand veins between sexes and across BR days. Using 2-D ultrasound, dorsal hand (DHV) and foot vein (DFV) responses (diameter; expressed as sq mm) to 40 mmHg of congestion pressure (compliance) and to intravenous infusion of phenylephrine (PE; 3160ng/min) were determined in 10 females and 16 males before and after 60 days of BR. The relation between changes in vein diameter (in response to pressure and PE), sex, limb, and BR days were determined using a mixed-effect linear regression. It was found that after 60 days of BR, DFV dilator response to pressure was significantly greater in females and significantly less in males compared to pre-BR. As expected, there were no differences in DHV dilator response between sexes nor was there a significant difference between pre and post measures within groups. Notably, the venoconstrictor response to infusions of PE in the DHV and DFV where similar between sexes and across BR days. In conclusion, this study demonstrates that after 60 days of BR, dorsal foot veins are more compliant in women and less compliant in men. Moreover, the changes in lower body vein compliance in females do

  5. NASA Ames Laminar Flow Supersonic Wind Tunnel (LFSWT) Tests of a 10 deg Cone at Mach 1.6

    NASA Technical Reports Server (NTRS)

    Wolf, Stephen W. D.; Laub, James A.

    1997-01-01

    This work is part of the ongoing qualification of the NASA Ames Laminar Flow Supersonic Wind Tunnel (LFSWT) as a low-disturbance (quiet) facility suitable for transition research. A 10 deg cone was tested over a range of unit Reynolds numbers (Re = 2.8 to 3.8 million per foot (9.2 to 12.5 million per meter)) and angles of incidence (O deg to 10 deg) at Mach 1.6. The location of boundary layer transition along the cone was measured primarily from surface temperature distributions, with oil flow interferometry and Schlieren flow visualization providing confirmation measurements. With the LFSWT in its normal quiet operating mode, no transition was detected on the cone in the test core, over the Reynolds number range tested at zero incidence and yaw. Increasing the pressure disturbance levels in the LFSWT test section by a factor of five caused transition onset on the cone within the test core, at zero incidence and yaw. When operating the LFSWT in its normal quiet mode, transition could only be detected in the test core when high angles of incidence (greater than 5 deg) for cones were set. Transition due to elevated pressure disturbances (Tollmien-Schlichting) and surface trips produced a skin temperature rise of order 4 F (2.2 C). Transition due to cross flows on the leeward side of the cone at incidence produced a smaller initial temperature rise of only order 2.5 F (1.4 C), which indicates a slower transition process. We can conclude that these cone tests add further proof that the LFSWT test core is normally low-disturbance (pressure fluctuations greater than 0.1%), as found by associated direct flow quality measurements discussed in this report. Furthermore, in a quiet test environment, the skin temperature rise is sensitive to the type of dominant instability causing transition. The testing of a cone in the LFSWT provides an excellent experiment for the development of advanced transition detection techniques.

  6. Effects of encouraged water drinking on thermoregulatory responses after 20 days of head-down bed rest in humans

    NASA Astrophysics Data System (ADS)

    Sato, Maki; Kanikowska, Dominika; Iwase, Satoshi; Shimizu, Yuuki; Inukai, Yoko; Nishimura, Naoki; Sugenoya, Junichi

    2009-09-01

    We tested the hypothesis that encouraged water drinking according to urine output for 20 days could ameliorate impaired thermoregulatory function under microgravity conditions. Twelve healthy men, aged 24 ± 1.5 years (mean ± SE), underwent -6° head-down bed rest (HDBR) for 20 days. During bed rest, subjects were encouraged to drink the same amount of water as the 24-h urine output volume of the previous day. A heat exposure test consisting of water immersion up to the knees at 42°C for 45 min after a 10 min rest (baseline) in the sitting position was performed 2 days before the 20-day HDBR (PRE), and 2 days after the 20-day HDBR (POST). Core temperature (tympanic), skin temperature, skin blood flow and sweat rate were recorded continuously. We found that the -6° HDBR did not increase the threshold temperature for onset of sweating under the encouraged water drinking regime. We conclude that encouraged water drinking could prevent impaired thermoregulatory responses after HDBR.

  7. Psychomotor performance during a 28 day head-down tilt with and without lower body negative pressure

    NASA Astrophysics Data System (ADS)

    Traon, A. Pavy-le; de Feneyrols, A. Rous; Cornac, A.; Abdeseelam, R.; N'uygen, D.; Lazerges, M.; Güell, A.; Bes, A.

    Several factors may affect psychomotor performance in space: sensory-motor changes, sleep disturbances, psychological modifications induced by the social isolation and confinement. However, psychomotor performance is difficult to assess. A battery of standardized and computerized tests, so-called "Automated Portable Test System" (APTS) was devised to ascertain the cognitive, perceptive and motor abilities and their possible fluctuations according to environmental effects. Antiorthostatic bedrest, often used to simulate weightlessness, (particularly cardiovascular modifications) also constitutes a situation of social confinement and isolation. During two bedrest experiments (with head-down tilt of -6°) of 28 days each, we intended to assess psychomotor performance of 6 males so as to determine whether: —on the one hand, it could be altered by remaining in decubitus; —on the other, the Lower Body Negative Pressure sessions, designed to prevent orthostatic intolerance back on Earth, could improve the performance. To accomplish this, part of the APTS tests as well as an automated perceptive attention test were performed. No downgrading of psychomotor performance was observed. On the contrary, the tasks were more accurately performed over time. In order to assess the experimental conditions on the acquisition phase, the learning curves were modelled. A beneficial effect of the LBNP sessions on simple tests involving the visual-motor coordination and attention faculties can only be regarded as a mere trend. Methods used in this experiment are also discussed.

  8. Effect of artificial gravity with exercise training on lung function during head-down bed rest in humans.

    PubMed

    Guo, Yinghua; Guo, Na; Liu, Changting; Wang, Delong; Wang, Junfeng; Sun, Xiqing; Fan, Shangchun; Wang, Changyong; Yang, Changbin; Zhang, Yu; Lu, Dongyuan; Yao, Yongjie

    2013-01-01

    There is evidence to suggest that microgravity/weightlessness can induce changes in lung physiology/function. We hypothesized that microgravity, induced by head-down bed rest (HDBR), would induce changes in lung function and that exercise training with artificial gravity (AG) would prevent these changes from occurring. Twelve participants were randomly assigned to a control or AG exercise countermeasure (CM) group (n = 6 per group) and 96 h of 6° HDBR. Participants in the CM group were exposed to AG (alternating 2 min intervals of +1·0 and +2·0 G) for 30 min, twice daily, during which time ergometric exercise (40 W intensity) was performed. Pulse rate, oxygen saturation (SO(2) ) and lung function were measured and compared between groups. The CM and control groups were similar in mean age, height and weight. There were no significant within or between group differences over time in pulse rate, SO(2) , vital capacity, inspiratory capacity, tidal volume, expiratory reserve volume, inspiratory reserve volume, minute ventilation, forced vital capacity, forced expiratory volume in 1 s, peak expiratory flow, maximal expiratory flow in 25%, 50% and 75% vital capacity, forced inspiratory vital capacity, forced inspiratory volume in 1 s and maximal voluntary ventilation. Microgravity induced by 96 h of HDBR does not appear to affect lung function in humans. Further, AG with exercise training does not change lung function during 96 h of HDBR in humans. PMID:23216762

  9. Effect of head-down bed rest on the neuroendocrine response to orthostatic stress in physically fit men.

    PubMed

    Koska, J; Ksinantová, L; Kvetnanský, R; Marko, M; Hamar, D; Vigas, M; Hatala, R

    2003-01-01

    The role of neuroendocrine responsiveness in the development of orthostatic intolerance after bed rest was studied in physically fit subjects. Head-down bed-rest (HDBR, -6 degrees, 4 days) was performed in 15 men after 6 weeks of aerobic training. The standing test was performed before, after training and on day 4 of the HDBR. Orthostatic intolerance was observed in one subject before and after training. The blood pressure response after training was enhanced (mean BP increments 18+/-2 vs. 13+/- 2 mm Hg, p<0.05, means +/- S.E.M.), although noradrenaline response was diminished (1.38+/-0.18 vs. 2.76+/-0.25 mol.l(-1), p<0.01). Orthostatic intolerance after HDBR was observed in 10 subjects, the BP response was blunted, and noradrenaline as well as plasma renin activity (PRA) responses were augmented (NA 3.10+/-0.33 mol.l(-1), p<0.001; PRA 2.98+/-1.12 vs. 0.85+/-0.15 ng.ml(-1), p<0.05). Plasma noradrenaline, adrenaline and aldosterone responses in orthostatic intolerant subjects were similar to the tolerant group. We conclude that six weeks of training attenuated the sympathetic response to standing and had no effect on the orthostatic tolerance. In orthostatic intolerance the BP response induced by subsequent HDBR was absent despite an enhanced sympathetic response. PMID:12790765

  10. Effect of head-down-tilt bed rest and hypovolemia on dynamic regulation of heart rate and blood pressure

    NASA Technical Reports Server (NTRS)

    Iwasaki, K. I.; Zhang, R.; Zuckerman, J. H.; Pawelczyk, J. A.; Levine, B. D.; Blomqvist, C. G. (Principal Investigator)

    2000-01-01

    Adaptation to head-down-tilt bed rest leads to an apparent abnormality of baroreflex regulation of cardiac period. We hypothesized that this "deconditioning response" could primarily be a result of hypovolemia, rather than a unique adaptation of the autonomic nervous system to bed rest. To test this hypothesis, nine healthy subjects underwent 2 wk of -6 degrees head-down bed rest. One year later, five of these same subjects underwent acute hypovolemia with furosemide to produce the same reductions in plasma volume observed after bed rest. We took advantage of power spectral and transfer function analysis to examine the dynamic relationship between blood pressure (BP) and R-R interval. We found that 1) there were no significant differences between these two interventions with respect to changes in numerous cardiovascular indices, including cardiac filling pressures, arterial pressure, cardiac output, or stroke volume; 2) normalized high-frequency (0.15-0.25 Hz) power of R-R interval variability decreased significantly after both conditions, consistent with similar degrees of vagal withdrawal; 3) transfer function gain (BP to R-R interval), used as an index of arterial-cardiac baroreflex sensitivity, decreased significantly to a similar extent after both conditions in the high-frequency range; the gain also decreased similarly when expressed as BP to heart rate x stroke volume, which provides an index of the ability of the baroreflex to alter BP by modifying systemic flow; and 4) however, the low-frequency (0.05-0.15 Hz) power of systolic BP variability decreased after bed rest (-22%) compared with an increase (+155%) after acute hypovolemia, suggesting a differential response for the regulation of vascular resistance (interaction, P < 0.05). The similarity of changes in the reflex control of the circulation under both conditions is consistent with the hypothesis that reductions in plasma volume may be largely responsible for the observed changes in cardiac

  11. Cardiopulmonary responses to acute hypoxia, head-down tilt and fluid loading in anesthetized dogs

    NASA Technical Reports Server (NTRS)

    Loeppky, J. A.; Scotto, P.; Riedel, C.; Avasthi, P.; Koshukosky, V.; Chick, T. W.

    1991-01-01

    Cardiopulmonary responses to acute hypoxia (HY), fluid loading by saline infusion (FL), and head-down tilt (HD) of mechanically ventilated anesthetized dogs were investigated by measuring thermodynamics and pulmonary gas exchange. It was found that HD decreased the total respiratory compliance both during HY and normoxia (NO) and that the reduction in compliance by FL was twice as large as by HD. Superimposing HD on HY doubled the increase in vascular resistance due to HY alone. In the systemic circulation, HD lowered the resistance to below NO levels. There was a significant positive correlation between the changes in blood volume and in pulmonary artery pressure for experimental transitions, suggesting that a shift in blood volume from systemic to pulmonary circulations and changes in the total blood volume may contribute substantially to these apparent changes in resistance.

  12. Terrain Portrayal for Synthetic Vision Systems Head-Down Displays Evaluation Results

    NASA Technical Reports Server (NTRS)

    Hughes, Monica F.; Glaab, Louis J.

    2007-01-01

    A critical component of SVS displays is the appropriate presentation of terrain to the pilot. At the time of this study, the relationship between the complexity of the terrain presentation and resulting enhancements of pilot SA and pilot performance had been largely undefined. The terrain portrayal for SVS head-down displays (TP-HDD) simulation examined the effects of two primary elements of terrain portrayal on the primary flight display (PFD): variations of digital elevation model (DEM) resolution and terrain texturing. Variations in DEM resolution ranged from sparsely spaced (30 arc-sec) to very closely spaced data (1 arc-sec). Variations in texture involved three primary methods: constant color, elevation-based generic, and photo-realistic, along with a secondary depth cue enhancer in the form of a fishnet grid overlay.

  13. Alterations in Skeletal Muscle Microcirculation of Head-Down Tilted Rats

    NASA Technical Reports Server (NTRS)

    Musacchia, X. J.; Stepke, Bernhard; Fleming, John T.; Joshua, Irving G.

    1992-01-01

    In this study we assessed the function of microscopic blood vessels in skeletal muscle (cremaster muscle) for alterations which may contribute to the observed elevation of blood pressure associated with head-down tilted whole body suspension (HDT/WBS), a model of weightlessness. Arteriolar baseline diameters, vasoconstrictor responses to norepinephrine (NE) and vasodilation to nitroprusside (NP) were assessed in control rats, rats suspended for 7 or 14 day HDT/WBS rats, and rats allowed to recover for 1 day after 7 days HDT/WBS. Neither baseline diameters nor ability to dilate were influenced by HDT/WBS. Maximum vasoconstriction to norepinephrine was significantly greater in arterioles of hypertensive 14 day HDT/WBS rats. This first study of the intact microvasculature in skeletal muscle indicates that an elevated contractility of arterioles to norepinephrine in suspended rats, and suggests an elevated peripheral resistance in striated muscle may contribute to the increase in blood pressures among animals subjected to HDT/WBS.

  14. Positional Asphyxia: Death Due to Unusual Head-Down Position in a Narrow Space.

    PubMed

    Chaudhari, Vinod Ashok; Ghodake, Dattatray G; Kharat, Rajesh D

    2016-06-01

    Death due to a head-down position with hyperflexion of the neck is a rare event. A person accidentally falling into a narrow space and remaining in an upside-down position with no timely recovery may experience positional or postural asphyxia. It is a critical condition arising out of particular body positions, leading to mechanical obstruction of respiration. The precipitating factors are intoxication due to alcohol, drugs, obesity, psychiatric illnesses, and injuries. A 30-year-old unmarried woman, weighing 82 kg and with a body mass index of 31.24, was found in a narrow space between the bed and the wall in a naked state and in a head-down position with hyperflexion of the neck. The distribution of lividity was consistent with the position of the body at the scene. Blood was oozing from the mouth and nostrils, and signs of asphyxia were present. The toxicological analyses of viscera, blood, and urine were negative for alcohol, drugs, and poisons. Glucose levels in the blood (86 mg/dL) as well as urine and vitreous humor levels (68 mg/dL) were within normal limits. On microscopic examination, there were no findings of coronary atherosclerosis, whereas the brain and lung were edematous. After meticulous examination, we ruled out sexual assault, autoerotic asphyxia, epilepsy, psychiatric illness, diabetes, toxicity, and coronary artery disease. Death was attributed to the accidental fall of the obese individual being stuck in a narrow space, resulting in positional asphyxia. It is imperative to recognize the precipitating or risk factors before labeling positional asphyxia as a cause of death. PMID:26840099

  15. Effects of saline loading during head down tilt on ANP and cyclic GMP levels and on urinary fluid excretion

    NASA Astrophysics Data System (ADS)

    Drummer, C.; Lang, R. E.; Baisch, F.; Blomqvist, G.; Heer, M.; Gerzer, R.

    In the present study the renal and humoral effects of acute saline infusions were investigated in six healthy male volunteers before, during and after a ten day period of -6° head-down-tilt (HDT). During the whole 23-day study period the subjects received a standardized diet including 40 ml water and 125 mg NaCl per kg body weight per day. After the infusion of 0.9% saline (22 ml/kg within 20 minutes) plasma atrial natriuretic peptide (ANP) levels were only slightly increased (not significant) at the end of the infusion, while plasma cyclic GMP levels were significantly increased by about 40% (p<0.05) one hour later. No difference was observed in the plasma ANP and cyclic GMP changes between the pre-HDT, the HDT and the post-HDT infusion experiment. Urine flow, sodium excretion and urinary cyclic GMP excretion were significantly increased (p<0.05 and below) by 100 to 300% during the second and third hour after each saline infusion. However, during these short-term periods only 20% of the infused water and less than 20% of the infused sodium were excreted. Furthermore, a significantly increased volume, sodium and cyclic GMP excretion was observed for over 48 hours after each fluid load experiment. These data suggest that HDT does not induce major alterations in the regulation of an acute saline infusion and plasma ANP does not play a major role in the diuretic/natriuretic effects of volume loading.

  16. Plasma volume shifts and exercise thermoregulation with water immersion and six-degree head-down tilt

    NASA Technical Reports Server (NTRS)

    Ertl, Andrew Carl

    1994-01-01

    The hypothesized fluid shifts and resultant responses that occur during spaceflight are simulated by six-degree head down tilt (HDT) and water immersion (WI). The purpose of this study was to compare exercise thermoregulation before and after physiologic mechanisms reduce plasma volume (PV) in response to 24-hr HDT (HDT24). A secondary study utilized WI to reproduce the PV reduction of HDT24. Seven males were studied in two conditions: during 70 minutes of supine cycling ergometry at 58 percent of peak oxygen consumption following 1-hr HDT (HDT1) and HDT24; and up to 6 hr WI at 34.5 C. Plasma volume was reduced by 10.4 percent in HDT24 when compared to HDT1. Pre-exercise rectal temperature, T(sub re), was an average 0.22 C higher after HDT24. Rectal temperature increased during exercise with no interaction between time and treatment. The reduced PV and elevated pre-exercise T(sub re) had offsetting effects on thermoregulatory mechanisms, suggesting no alteration in the response at a given T(sub re). Plasma volume was reduced by 4.3 +/- 2.3 percent and 1.1 +/- 1.8 percent following HDT24 and WI, respectively, compared to upright chair rest. Although the reductions in PV were not significantly different, great intra-individual variability was evident. The ability to reproduce PV changes consistently with HDT and WI is limited by this variability.

  17. Restoration of plasma volume after 16 days of head-down tilt induced by a single bout of maximal exercise

    NASA Technical Reports Server (NTRS)

    Convertino, V. A.; Engelke, K. A.; Ludwig, D. A.; Doerr, D. F.

    1996-01-01

    Seven healthy men performed maximal exercise 24 h before the end of 16 days exposure to 6 degrees head-down tilt (HDT) to test the hypothesis that such an exercise technique could restore plasma volume (PV) at the end of a simulated space mission. Exercise consisted of supine cycling with graded work rates increasing by 16 W/min to volitional fatigue and required an average of 16 min. The experimental protocol was a standard cross-over design in which the order of treatment (exercise or control) was counterbalanced across all seven subjects. PV, fluid intake (ad libitum), urine output, renal function, and hormones associated with fluid homeostasis were measured before HDT, 24 h before the end of HDT just prior to exercise, and at the end of HDT 24 h after exercise. HDT reduced PV by 16% in both control and exercise conditions. Maximal exercise completely restored plasma volume within 24 h to 3.9 +/- 3.2% of pre-HDT levels despite continued HDT. Compared with control, exercise induced a 660-ml larger positive fluid balance because of greater fluid intake and reduced urine volume during the 24 h after exercise. These results suggest that one bout of maximal leg exercise before return from 16 days of spaceflight may be completely effective in stimulating thirst and restoring plasma volume to preflight levels.

  18. Use of an Android application “clinometer” for measurement of head down tilt given during subarachnoid block

    PubMed Central

    Dixit, RB; Neema, MM

    2016-01-01

    Context: Head down tilt is given to patients after sub arachnoid block for adjustment of height of block. However, the amount of tilt given is subjective and cannot be documented. Aims: We used an android application named “clinometer” to measure exact degree of tilt given by anesthesiologists as their routine practice. Settings and Design: This observational study, at a medical college hospital, was done in 130 patients given sub arachnoid block for lower abdominal surgeries. Materials and Methods: We observed and documented vital data of patients and measured tilt given by application “clinometer.” Results: We observed that the application was easy to use and measured tilt each time. The result obtained can be documented, digitally saved and transferred. In 130 patients studied, we observed incidence of degree of tilt as follows: 6-8° tilt in 38 patients (29.23%), 8-10 in 36 patients (27.69%), 10-12 in 30 patients (23.08%), 12-14 in 12 patients (9.23%) and 14-16° tilt in 14 patients (10.77%). Use of application was received with enthusiasm by practicing anesthesiologists. Various possible uses of this application are discussed. PMID:26955307

  19. Influence of head-down bed rest on the circadian rhythms of hormones and electrolytes involved in hydroelectrolytic regulation

    NASA Technical Reports Server (NTRS)

    Millet, C.; Custaud, M. A.; Allevard, A. M.; Zaouali-Ajina, M.; Monk, T. H.; Arnaud, S. B.; Claustrat, B.; Gharib, C.; Gauquelin-Koch, G.

    2001-01-01

    We investigated in six men the impact of a 17-day head-down bed rest (HDBR) on the circadian rhythms of the hormones and electrolytes involved in hydroelectrolytic regulation. This HDBR study was designed to mimic an actual spaceflight. Urine samples were collected at each voiding before, during and after HDBR. Urinary excretion of aldosterone, arginine vasopressin (AVP), cyclic guanosine monophosphate (cGMP), cortisol, electrolytes (Na+ and K+) and creatinine were determined. HDBR resulted in a significant reduction of body mass (P < 0.01) and of caloric intake [mean (SEM) 2,778 (37) kcal.24 h(-1) to 2,450 (36) kcal.24 h(-1), where 1 kcal.h(-1) = 1.163 J.s(-1); P< 0.01]. There was a significant increase in diastolic blood pressure [71.8 (0.7) mmHg vs 75.6 (0.91) mmHg], with no significant changes in either systolic blood pressure or heart rate. The nocturnal hormonal decrease of aldosterone was clearly evident only before and after HDBR, but the day/night difference did not appear during HDBR. The rhythm of K+ excretion was unchanged during HDBR, whereas for Na+ excretion, a large decrease was shown during the night as compared to the day. The circadian rhythm of cortisol persisted. These data suggest that exposure to a 17-day HDBR could induce an exaggeration of the amplitude of the Na+ rhythm and abolition of the aldosterone rhythm.

  20. A Proposed Study Examining Individual Differences in Temporal Profiles of Cardiovascular Responses to Head Down Tilt During Fluid Loading

    NASA Technical Reports Server (NTRS)

    Cowings, Patricia; Toscano, William; Winther, Sean; Martinez, Jacqueline; Dominguez, Margaret

    2012-01-01

    Susceptibility of healthy astronauts to orthostatic hypotension and presyncope is exacerbated upon return from spaceflight. The effect of altered gravity during space flight and planetary transition on human cardiovascular function is of critical importance to maintenance of astronaut health and safety. Hypovolemia, reduced plasma volume, is suspected to play an important role in cardiovascular deconditioning following exposure to spaceflight, which may lead to increased peripheral resistance, attenuated arterial baroreflex, and changes in cardiac function. A promising countermeasure for post-flight orthostatic intolerance is fluid loading used to restore lost plasma volume by giving crew salt tablets and water prior to re-entry. The main purpose of the proposed study is to define the temporal profile of cardiac responses to simulated 0-G conditions before and following a fluid loading countermeasure. 8 men and 8 women will be tested during 4 hour exposures at 6o head down tilt (HDT). Each subject will be given two exposures to HDT on separate days, one with and one without fluid loading (one liter of 0.9% saline solution). Stand tests (orthostatic stress) will be done before and after each HDT. Cardiac measures will be obtained with both impedance cardiography and echo ultrasound

  1. Interpersonal relationships in isolation and confinement: Long-term bed rest in head-down tilt position

    NASA Astrophysics Data System (ADS)

    Karine, Weiss; Gabriel, Moser

    The long-term bed-rest was organized by ESA and CNES, in order to simulate the physiological effects of weightlessness: eight volunteers had to stay 42 days in bed, in a head down tilt position (-6 °). There were two subjects in a room, they could not be alone and it was difficult for them to have their own personal space and intimacy. In these circumstances, as in outer space, interpersonal relationships were of prime importance. This situation enabled us, through systematic observation, to analyze the evolution of the relational behavior in dyads, and to quote some social indicators of adaptation. Results show significant withdrawal, and the time spent alone was marked by the emergence, during the experiment, of specific preferential activities. Behavioral contagion was observed in each dyad (people engaged in the same activities at the same time), except in the one case of abandon. Moreover, the highest rates of inactivity and withdrawal were noted in this case. Verbal indicators were useful to comment these results and showed that, for all the dyads, one of the two subjects always played a regulating role by expressing a very positive perception of the situation. These results emphasize the importance of psycho-sociological factors in isolation and confinement. Thus, it appears that different modalities of interpersonal relationships, and not only verbal interactions, play a significant role in adaptation to stress situations.

  2. No effect of artificial gravity on lung function with exercise training during head-down bed rest

    NASA Astrophysics Data System (ADS)

    Su, Longxiang; Guo, Yinghua; Wang, Yajuan; Wang, Delong; Liu, Changting

    2016-04-01

    The aim of this study is to explore the effectiveness of microgravity simulated by head-down bed rest (HDBR) and artificial gravity (AG) with exercise on lung function. Twenty-four volunteers were randomly divided into control and exercise countermeasure (CM) groups for 96 h of 6° HDBR. Comparisons of pulse rate, pulse oxygen saturation (SpO2) and lung function were made between these two groups at 0, 24, 48, 72, 96 h. Compared with the sitting position, inspiratory capacity and respiratory reserve volume were significantly higher than before HDBR (0° position) (P < 0.05). Vital capacity, expiratory reserve volume, forced vital capacity, forced expiratory volume in 1 s, forced inspiratory vital capacity, forced inspiratory volume in 1 s, forced expiratory flow at 25, 50, and 75%, maximal mid-expiratory flow and peak expiratory flow were all significantly lower than those before HDBR (P < 0.05). Neither control nor CM groups showed significant differences in pulse rate, SpO2, pulmonary volume and pulmonary ventilation function over the HDBR observation time. Postural changes can lead to variation in lung volume and ventilation function, but a HDBR model induced no changes in pulmonary function and therefore should not be used to study AG countermeasures.

  3. Blood volume regulating hormones response during two space related simulation protocols: Four-week confinement and head-down bed-rest

    NASA Astrophysics Data System (ADS)

    Maillet, A.; Gauquelin, G.; Gunga, H. C.; Fortrat, J. O.; Kirsch, K.; Guell, A.; Bizollon, Ch. A.; Gharib, C.

    1995-04-01

    The volume of regulating hormones (renin, aldosterone, arginine vasopressin and atrial natriuretic factor), electrolytes and creatinine concentrations, and blood pressure were measured in two different four-week experimental protocols: respectively -6 ° head-down bed-rest (5 subjects) and confinement (6 subjects). We observed a significant increase ( P < 0.01 at D2 vs D-5) of systolic blood pressure during confinement and a different level of response for some hormones, especially for arginine vasopressin (300% increase during confinement instead of 50% during bed-rest). The renin-angiotensin-aldosterone system was enhanced during confinement and head-down bed-rest. In both conditions, we obtained a similar pattern of response for blood volume regulating hormones. During confinement, two main factors were inactivity and stress activation of the sympathetic nervous system. In the bed-rest study the response is principally due to the fluid shift and blood volume adaptation but it is not possible to exclude the role of inactivity and stress.

  4. Exercise Thermoregulation in Men after One and 24-hours of 6 Degree Head-Down Tilt

    NASA Technical Reports Server (NTRS)

    Ertl, A. C.; Dearborn, A. S.; Weldhofer, A. R.; Bernauer, E. M.; Greenleaf, J. E.

    1998-01-01

    Exercise thermoregulation exercise is dependent on heat loss by increased skin blood flow (convective and conductive heat loss) and through enhanced sweating (evaporative heat loss). Reduction of plasma volume (PV), increased plasma osmolality, physical deconditioning, and duration of exposure to simulated and actual microgravity reduces the ability to thermoregulate during exercise.

  5. The Effect of Ambient Temperature on the Cardiovascular Responses to Microgravity as Simulated by six Degrees Head Down Tilt (HDT)

    NASA Astrophysics Data System (ADS)

    Nangalia, Vishal; Ernsting, John

    Background: To determine the effect of ambient temperature on the thermoregulatory and cardiovascular responses to microgravity as simulated by six degrees head down tilt (HDT). Hypothesis: The thermoregulatory and cardiovascular responses to 6°HDT are unaffected by ambient temperatures between 12° and 32°C. Method: Each of five volunteer subjects (18-24 y.) underwent three separate 6 h exposures in a climatic chamber whilst lying supine with 6°HDT. The ambient temperatures for the first 5 h of the exposure were 12°, 22° and 32°C. At the beginning of the sixth hour, the ambient temperature was either increased or decreased by 10°C depending on the initial temperature. Heart rate, blood pressure, forearm bloodflow, core and skin temperatures, urine output and body weight were measured before, during and after each exposure. Results: Mean arterial pressure was increased in all exposures, though the increase varied with the ambient temperature. Pulse pressure after 5 h HDT increased in the 32°C exposure, remained unchanged at 22°C and decreased at 12°C. The threshold for thermoregulatory increases in forearm vascular conductance was lowered. Core temperature of the body increased in the exposures to 32°C and 22°C. The reduction in body weight (mean 1 kg.) was identical in all exposures whilst the urine output varied with ambient temperature. No significant changes occurred in any variable when the ambient temperature was changed by 10°C at the end of the fifth hour. Conclusions: The cardiovascular responses to 6 h exposure to 6° HDT, are affected by the ambient temperature.

  6. First Ground-Based Infrared Solar Absorption Measurements of Free Tropospheric Methanol (CH3OH): Multidecade Infrared Time Series from Kitt Peak (31.9 deg N 111.6 deg W): Trend, Seasonal Cycle, and Comparison with Previous Measurements

    NASA Technical Reports Server (NTRS)

    Rinsland, Curtis P.; Mahieu, Emmanuel; Chiou, Linda; Herbin, Herve

    2009-01-01

    Atmospheric CH3OH (methanol) free tropospheric (2.09-14-km altitude) time series spanning 22 years has been analyzed on the basis of high-spectral resolution infrared solar absorption spectra of the strong vs band recorded from the U.S. National Solar Observatory on Kitt Peak (latitude 31.9degN, 111.6degW, 2.09-km altitude) with a 1-m Fourier transform spectrometer (FTS). The measurements span October 1981 to December 2003 and are the first long time series of CH3OH measurements obtained from the ground. The results were analyzed with SFIT2 version 3.93 and show a factor of three variations with season, a maximum at the beginning of July, a winter minimum, and no statistically significant long-term trend over the measurement time span.

  7. First Ground-Based Infrared Solar Absorption Measurements of Free Tropospheric Methanol (CH3OH): Multidecade Infrared Time Series from Kitt Peak (31.9 deg N 111.6 deg W): Trend, Seasonal Cycle, and Comparison with Previous Measurements

    NASA Technical Reports Server (NTRS)

    Rinsland, Curtis P.; Mahieu, Emmanuel; Chiou, Linda; Herbin, Herve

    2009-01-01

    Atmospheric CH3OH (methanol) free tropospheric (2.09-14-km altitude) time series spanning 22 years has been analyzed on the basis of high-spectral resolution infrared solar absorption spectra of the strong n8 band recorded from the U.S. National Solar Observatory on Kitt Peak (latitude 31.9degN, 111.6degW, 2.09-km altitude) with a 1-m Fourier transform spectrometer (FTS). The measurements span October 1981 to December 2003 and are the first long time series of CH3OH measurements obtained from the ground. The results were analyzed with SFIT2 version 3.93 and show a factor of three variations with season, a maximum at the beginning of July, a winter minimum, and no statistically significant long-term trend over the measurement time span.

  8. Early processing variations in selective attention to the color and direction of moving stimuli during 30 days head-down bed rest

    NASA Astrophysics Data System (ADS)

    Wang, Lin-Jie; He, Si-Yang; Niu, Dong-Bin; Guo, Jian-Ping; Xu, Yun-Long; Wang, De-Sheng; Cao, Yi; Zhao, Qi; Tan, Cheng; Li, Zhi-Li; Tang, Guo-Hua; Li, Yin-Hui; Bai, Yan-Qiang

    2013-11-01

    Dynamic variations in early selective attention to the color and direction of moving stimuli were explored during a 30 days period of head-down bed rest. Event-related potentials (ERPs) were recorded at F5, F6, P5, P6 scalp locations in seven male subjects who attended to pairs of bicolored light emitting diodes that flashed sequentially to produce a perception of movement. Subjects were required to attend selectively to a critical feature of the moving target, e.g., color or direction. The tasks included: a no response task, a color selective response task, a moving direction selective response task, and a combined color-direction selective response task. Subjects were asked to perform these four tasks on: the 3rd day before bed rest; the 3rd, 15th and 30th day during the bed rest; and the 5th day after bed rest. Subjects responded quickly to the color than moving direction and combined color-direction response. And they had a longer reaction time during bed rest on the 15th and 30th day during bed rest after a relatively quicker response on the 3rd day. Using brain event-related potentials technique, we found that in the color selective response task, the mean amplitudes of P1 and N1 for target ERPs decreased in the 3rd day during bed rest and 5th day after bed rest in comparison with pre-bed rest, 15th day and 30th day during bed rest. In the combined color-direction selective response task, the P1 latencies for target ERPs on the 3rd and 30th day during bed rest were longer than on the 15th day during bed rest. As 3rd day during bed rest was in the acute adaptation period and 30th day during bed rest was in the relatively adaptation stage of head-down bed rest, the results help to clarify the effects of bed rest on different task loads and patterns of attention. It was suggested that subjects expended more time to give correct decision in the head-down tilt bed rest state. A difficulty in the recruitment of brain resources was found in feature selection task

  9. Effects of leg strength and bicycle ergometry exercise on cardiovascular deconditioning after 30-day head-down bed rest

    NASA Astrophysics Data System (ADS)

    Wu, Bin; Liu, Yusheng; Sun, Hongyi; Zhao, Dongming; Wang, Yue; Wu, Ping; Ni, Chengzhi

    2010-10-01

    The purpose of this study is to determine if the intermittent leg muscular strength exercise and bicycle ergometry exercise could attenuate cardiovascular deconditioning induced by prolonged -6° head-down bed rest (HDBR). Fifteen male subjects were randomly allocated into group A ( n=5, 30 days HDBR without exercise), group B ( n=5, 30 days HDBR with leg muscular strength exercise) and group C ( n=5, 30 days HDBR with bicycle ergometry exercise). The orthostatic tolerance (OT) was determined by +75°/20 min head-up tilt (HUT) test and the submaximal exercise capacity was determined by bicycle ergometry before and after HDBR. The results were as follows: (1) Compared with that before HDBR, OT time decreased dramatically by 57.6% ( p<0.001) after HDBR in group A, while it decreased by 36.4% ( p=0.084) in group B and by 34.7% ( p=0.062) in group C. (2) Compared with that before HDBR, the submaximal exercise time decreased significantly by 17.7% ( p<0.05) and 21.1% ( p<0.05) in groups A and B, respectively, after HDBR. However, it had no change (+1.3%, p>0.77) in group C. (3) compared with that before HDBR, the changes of heart rate (HR) and blood pressure were slightly improved in group B and C, while deteriorated in group A during orthostatic test and exercise test after HDBR. The results indicate that leg muscular strength exercise and bicycle ergometry exercise could partially attenuate the cardiovascular deconditioning induced by 30 d HDBR, and the latter exercise training could fully provide the protection for the loss of exercise capacity.

  10. Three-dimensional audio versus head-down traffic alert and collision avoidance system displays.

    PubMed

    Begault, D R; Pittman, M T

    1996-01-01

    The advantage of a head-up auditory display for situational awareness was evaluated in an experiment designed to measure and compare the acquisition time for capturing visual targets under two conditions: standard head-down Traffic Alert and Collision Avoidance System display and three-dimensional (3-D) audio Traffic Alert and Collision Avoidance System presentation. (The technology used for 3-D audio presentation allows a stereo headphone user to potentially localize a sound at any externalized position in 3-D auditory space). Ten commercial airline crews were tested under full-mission simulation conditions at the NASA-Ames Crew-Vehicle Systems Research Facility Advanced Concepts Flight Simulator. Scenario software generated targets corresponding to aircraft that activated a 3-D aural advisory (the head-up auditory condition) or a standard, visual-audio TCAS advisory (map display with monaural audio alert). Results showed a significant difference in target acquisition time between the two conditions, favoring the 3-D audio Traffic Alert and Collision Avoidance System condition by 500 ms. PMID:11539173

  11. Skin sympathetic outflow during head-down neck flexion in humans.

    PubMed

    Ray, C A; Hume, K M; Shortt, T L

    1997-09-01

    We have previously demonstrated increases in muscle sympathetic nerve activity during head-down neck flexion (HDNF). The purpose of the present study was to determine if HDNF also activates skin sympathetic nerve activity (SSNA). SSNA, heart rate, arterial pressure, skin blood flow, calf blood flow, and calculated calf vascular resistance (mean arterial pressure/calf blood flow) were determined in 12 subjects during 3 min of baseline (lying prone with chin supported) and 3 min of HDNF. There were no significant changes in heart rate and arterial pressures during HDNF; however, diastolic and mean arterial pressure tended to increase slightly. Calf blood flow decreased 22% and calf vascular resistance increased 46% during HDNF. SSNA did not significantly change during HDNF. In three subjects we measured both muscle and skin sympathetic nerve activity during HDNF. In these trials, muscle sympathetic nerve activity consistently increased, but SSNA did not. The results indicate that HDNF in humans activates muscle sympathetic nerve activity, but does not activate SSNA. Thus vestibular stimulation may elicit differential activation of sympathetic outflow in humans. PMID:9321897

  12. Acute and chronic head-down tail suspension diminishes cerebral perfusion in rats

    NASA Technical Reports Server (NTRS)

    Wilkerson, M. Keith; Colleran, Patrick N.; Delp, Michael D.

    2002-01-01

    The purpose of this study was to test the hypothesis that regional brain blood flow and vascular resistance are altered by acute and chronic head-down tail suspension (HDT). Regional cerebral blood flow, arterial pressure, heart rate, and vascular resistance were measured in a group of control rats during normal standing and following 10 min of HDT and in two other groups of rats after 7 and 28 days of HDT. Heart rate was not different among conditions, whereas mean arterial pressure was elevated at 10 min of HDT relative to the other conditions. Total brain blood flow was reduced from that during standing by 48, 24, and 27% following 10 min and 7 and 28 days of HDT, respectively. Regional blood flows to all cerebral tissues and the eyes were reduced with 10 min of HDT and remained lower in the eye, olfactory bulbs, left and right cerebrum, thalamic region, and the midbrain with 7 and 28 days of HDT. Total brain vascular resistance was 116, 44, and 38% greater following 10 min and 7 and 28 days of HDT, respectively, relative to that during control standing. Vascular resistance was elevated in all cerebral regions with 10 min of HDT and remained higher than control levels in most brain regions. These results demonstrate that HDT results in chronic elevations in total and regional cerebral vascular resistance, and this may be the underlying stimulus for the HDT-induced smooth muscle hypertrophy of cerebral resistance arteries.

  13. Focal Gray Matter Plasticity as a Function of Long Duration Head-down Tilt Bed Rest

    NASA Technical Reports Server (NTRS)

    Koppelmans, Vincent; Erdeniz, Burak; DeDios, Yiri; Wood, Scott; Reuter-Lorenz, Patricia; Kofman, Igor; Bloomberg, Jacob; Mulavara, Ajitkumar; Seidler, Rachael

    2014-01-01

    Long duration spaceflight (i.e., 22 days or longer) has been associated with changes in sensorimotor systems, resulting in difficulties that astronauts experience with posture control, locomotion, and manual control. The microgravity environment is an important causal factor for spaceflight induced sensorimotor changes. Whether these sensorimotor changes may be related to structural and functional brain changes is yet unknown. However, increased intracranial pressure that by itself has been related to microgravity-induced bodily fluid shifts: [1] has been associated with white matter microstructural damage, [2] Thus, it is possible that spaceflight may affect brain structure and thereby cognitive functioning. Long duration head-down tilt bed rest has been suggested as an exclusionary analog to study microgravity effects on the sensorimotor system, [3] Bed rest mimics microgravity in body unloading and bodily fluid shifts. In consideration of the health and performance of crewmembers both in- and post-flight, we are conducting a prospective longitudinal 70-day bed rest study as an analog to investigate the effects of microgravity on brain structure, and [4] Here we present results of the first eight subjects.

  14. Renal Function of Rats in Response to 37 Days of Head-Down Tilt

    NASA Technical Reports Server (NTRS)

    Wang, Tommy J.; Wade, Charles E.; Dalton, Bonnie P. (Technical Monitor)

    2001-01-01

    Spaceflight induces changes in human renal function, suggesting similar changes may occur in rats. Since rats continue to be the prime mammalian model for study in space, the effects of chronic microgravity on rat renal function should be clarified. Acute studies in rats using the ground-based microgravity simulation model, head-down tilt (HDT), have shown increases in glomerular filtration rate (GFR), electrolyte excretion, and a diuresis. However, long term effects of HDT have not been studied extensively. This study was performed to elucidate rat renal function following long-term simulated microgravity. Chronic exposure to HDT will cause an increase in GFR and electrolyte excretion in rats, similar to acute exposures, and lead to a decrease in the fractional excretion of filtered electrolytes. Experimental animals (HDT, n=10) were tail-suspended for 37 days and renal function compared to ambulatory controls (AMB, n=10). On day 37 of HDT, GFR, osmolal clearance, and electrolyte excretion were decreased, while plasma osmolality and free water clearance were increased. Urine output remained similar between groups. The fractional excretion of the filtered electrolytes was unchanged except for a decrease in the percentage of filtered calcium excreted. Chronic exposure to HDT results in decreased GFR and electrolyte excretion, but the fractional excretion of filtered electrolytes remained primarily unaffected.

  15. Head-down-tilt bed rest alters forearm vasodilator and vasoconstrictor responses

    NASA Technical Reports Server (NTRS)

    Shoemaker, J. K.; Hogeman, C. S.; Silber, D. H.; Gray, K.; Herr, M.; Sinoway, L. I.

    1998-01-01

    To test the hypothesis that head-down-tilt bed rest (HDBR) for 14 days alters vascular reactivity to vasodilatory and vasoconstrictor stimuli, the reactive hyperemic forearm blood flow (RHBF, measured by venous occlusion plethysmography) and mean arterial pressure (MAP, measured by Finapres) responses after 10 min of circulatory arrest were measured in a control trial (n = 20) and when sympathetic discharge was increased by a cold pressor test (RHBF + cold pressor test; n = 10). Vascular conductance (VC) was calculated (VC = RHBF/MAP). In the control trial, peak RHBF at 5 s after circulatory arrest (34.1 +/- 2.5 vs. 48.9 +/- 4.3 ml . 100 ml-1 . min-1) and VC (0.34 +/- 0.02 vs. 0.53 +/- 0.05 ml . 100 ml-1 . min-1 . mmHg-1) were reduced in the post- compared with the pre-HDBR tests (P < 0. 05). Total excess RHBF over 3 min was diminished in the post- compared with the pre-HDBR trial (84.8 vs. 117 ml/100 ml, P < 0.002). The ability of the cold pressor test to lower forearm blood flow was less in the post- than in the pre-HDBR test (P < 0.05), despite similar increases in MAP. These data suggest that regulation of vascular dilation and the interaction between dilatory and constrictor influences were altered with bed rest.

  16. Long Duration Head Down Tilt Bed Rest Effects on Neurocognitive Performance: Extent, Longevity and Neural Bases

    NASA Technical Reports Server (NTRS)

    Seidler, R. D.; Mulavara, A. P.; Koppelmans, V.; Cassady, K.; Yuan, P.; Kofman, I. S.; De Dios, Y. E.; Szecsy, D. L.; Riascos-Castaneda, R F.; Wood, S. J.

    2016-01-01

    We are conducting ongoing experiments in which we are performing structural and functional magnetic resonance brain imaging to identify the relationships between changes in neurocognitive function and neural structural alterations following a six month International Space Station mission and following 70 days exposure to a spaceflight analog, head down tilt bedrest. Our central hypothesis is that measures of brain structure, function, and network integrity will change from pre to post intervention (spaceflight, bedrest). Moreover, we predict that these changes will correlate with indices of cognitive, sensory, and motor function in a neuroanatomically selective fashion. Our interdisciplinary approach utilizes cutting edge neuroimaging techniques and a broad ranging battery of sensory, motor, and cognitive assessments that will be conducted preflight, during flight, and post flight to investigate potential neuroplastic and maladaptive brain changes in crewmembers following long-duration spaceflight. Success in this endeavor would 1) result in identification of the underlying neural mechanisms and operational risks of spaceflight-induced changes in behavior, and 2) identify whether a return to normative behavioral function following re-adaptation to Earth's gravitational environment is associated with a restitution of brain structure and function or instead is supported by substitution with compensatory brain processes. In this presentation I will provide an overview of changes in behavior, brain structure, and brain function that we are observing in our bed rest participants in comparison to normative control subjects.

  17. Effects of 14 days of head-down tilt bed rest on cutaneous vasoconstrictor responses in humans

    NASA Technical Reports Server (NTRS)

    Wilson, Thad E.; Shibasaki, Manabu; Cui, Jian; Levine, Benjamin D.; Crandall, Craig G.

    2003-01-01

    This study tested the hypothesis that head-down tilt bed rest (HDBR) reduces adrenergic and nonadrenergic cutaneous vasoconstrictor responsiveness. Additionally, an exercise countermeasure group was included to identify whether exercise during bed rest might counteract any vasoconstrictor deficits that arose during HDBR. Twenty-two subjects underwent 14 days of strict 6 degrees HDBR. Eight of these 22 subjects did not exercise during HDBR, while 14 of these subjects exercised on a supine cycle ergometer for 90 min a day at 75% of pre-bed rest heart rate maximum. To assess alpha-adrenergic vasoconstrictor responsiveness, intradermal microdialysis was used to locally administer norepinephrine (NE), while forearm skin blood flow (SkBF; laser-Doppler flowmetry) was monitored over microdialysis membranes. Nonlinear regression modeling was used to identify the effective drug concentration that caused 50% of the cutaneous vasoconstrictor response (EC(50)) and minimum values from the SkBF-NE dose-response curves. In addition, the effects of HDBR on nonadrenergic cutaneous vasoconstriction were assessed via the venoarteriolar response of the forearm and leg. HDBR did not alter EC(50) or the magnitude of cutaneous vasoconstriction to exogenous NE administration regardless of whether the subjects exercised during HDBR. Moreover, HDBR did not alter the forearm venoarteriolar response in either the control or exercise groups during HDBR. However, HDBR significantly reduced the magnitude of cutaneous vasoconstriction due to the venoarteriolar response in the leg, and this response was similarly reduced in the exercise group. These data suggest that HDBR does not alter cutaneous vasoconstrictor responses to exogenous NE administration, whereas cutaneous vasoconstriction of the leg due to the venoarteriolar response is reduced after HDBR. It remains unclear whether attenuated venoarteriolar responses in the lower limbs contribute to reduced orthostatic tolerance after bed rest and

  18. Effect of space flight and head-down bedrest on neuroendocrine response to metabolic stress in physically trained subjects.

    PubMed

    Kvetnanský, R; Ksinantová, L; Koska, J; Noskov, V B; Vigas, M; Grigoriev, A I; Macho, L

    2004-07-01

    The aim of this study was to evaluate the association of plasma epinephrine (EPI) and norepinephrine (NE) responses to insulin induced hypoglycemia (ITT) 3 weeks before the space flight (SF), on the 5th day of SF, on the 2nd and 16th days after the landing in the first Slovak astronaut, and before and on the 5th day of prolonged subsequent head-down (-6 degrees) bed rest (BR) in 15 military aircraft pilots. Blood samples during the test were collected via cannula inserted into cubital vein, centrifuged in the special appliance Plasma-03, frozen in Kryogem-03, and at the end of the 8-day space flight transferred to Earth in special container for hormonal analysis. Insulin hypoglycemia was induced by i.v. administration of 0.1 IU/kg BW insulin (Actrapid HM) in bolus. Insulin administration led to a comparable hypoglycemia in pre-flight, in-flight conditions and before and after bed rest. ITT led to a pronounced increase in EPI levels and moderate increase in NE in pre-flight studies. However, an evidently reduced EPI response was found after insulin administration during SF and during BR. Thus, during the real microgravity in SF and simulated microgravity in BR, insulin-induced hypoglycemia activates the adrenomedullary system to less extent than at conditions of the Earth gravitation. Post-flight changes in EPI and NE levels did not significantly differ from those of pre-flight since SF was relatively short (8 days) and the readaptation to Earth gravitation was fast. It seems, that an increased blood flow in brain might be responsible for the reduced EPI response to insulin. Responses to ITT in physically fit subjects indicate the stimulus specificity of deconditioning effect of 5 days bed rest on stress response. Thus, the data indicate that catecholamine responses to ITT are reduced after exposure to real as well as simulated microgravity. PMID:16231455

  19. A single bout of exhaustive exercise affects integrated baroreflex function after 16 days of head-down tilt

    NASA Technical Reports Server (NTRS)

    Engelke, K. A.; Doerr, D. F.; Convertino, V. A.

    1995-01-01

    We tested the hypothesis that one bout of maximal exercise performed 24 h before reambulation from 16 days of 6 degrees head-down tilt (HDT) could increase integrated baroreflex sensitivity. Isolated carotid-cardiac and integrated baroreflex function was assessed in seven subjects before and after two periods of HDT separated by 11 mo. On the last day of one HDT period, subjects performed a single bout of maximal cycle ergometry (exercise). Subjects did not exercise after the other HDT period (control). Carotid-cardiac baroreflex sensitivity was evaluated using a neck collar device. Integrated baroreflex function was assessed by recording heart rate (HR) and blood pressure (MAP) during a 15-s Valsalva maneuver (VM) at a controlled expiratory pressure of 30 mmHg. The ratio of change in HR to change in MAP (delta HR/ delta MAP) during phases II and IV of the VM was used as an index of cardiac baroreflex sensitivity. Baroreflex-mediated vasoconstriction was assessed by measuring the late phase II rise in MAP. Following HDT, carotid-cardiac baroreflex sensitivity was reduced (2.8 to 2.0 ms/mmHg; P = 0.05) as was delta HR/ delta MAP during phase II (-1.5 to -0.8 beats/mmHg; P = 0.002). After exercise, isolated carotid baroreflex activity and phase II delta HR/ delta MAP returned to pre-HDT levels but remained attenuated in the control condition. Phase IV delta HR/ delta MAP was not altered by HDT or exercise. The late phase II increase of MAP was 71% greater after exercise compared with control (7 vs. 2 mmHg; P = 0.041).(ABSTRACT TRUNCATED AT 250 WORDS).

  20. Six-Degree Head-Down Tilt Bed Rest: Forty Years of Development as a Physiological Analog for Weightlessness

    NASA Technical Reports Server (NTRS)

    Smith, Jeffrey D.; Cromwell, Ronita L.; Kundrot, Craig E.; Charles, John B.

    2011-01-01

    Early on, bed rest was recognized as a method for inducing many of the physiological changes experienced by spaceflight. Head-down tilt (HDT) bed rest was first introduced as an analog for spaceflight by a Soviet team led by Genin and Kakurin. Their study was performed in 1970 (at -4 degrees) and lasted for 30 days; results were reported in the Russian Journal of Space Biology (Kosmicheskaya Biol. 1972; 6(4): 26-28 & 45-109). The goal was to test physiological countermeasures for cosmonauts who would soon begin month-long missions to the Salyut space station. HDT was chosen to produce a similar sensation of blood flow to the head reported by Soyuz cosmonauts. Over the next decade, other tilt angles were studied and comparisons with spaceflight were made, showing that HDT greater than 4 degrees was superior to horizontal bed rest for modeling acute physiological changes observed in space; but, at higher angles, subjects experienced greater discomfort without clearly improving the physiological comparison to spaceflight. A joint study performed by US and Soviet investigators, in 1979, set the goal of standardization of baseline conditions and chose 6-degrees HDT. This effectively established 6-degree HDT bed rest as the internationally-preferred analog for weightlessness and, since 1990, nearly all further studies have been conducted at 6-degrees HDT. A thorough literature review (1970-2010) revealed 534 primary scientific journal articles which reported results from using HDT as a physiological analog for spaceflight. These studies have ranged from as little as 10 minutes to the longest duration of 370 days. Long-term studies lasting four weeks or more have resulted in over 170 primary research articles. Today, the 6-degree HDT model provides a consistent, thoroughly-tested, ground-based analog for spaceflight and allows the proper scientific controls for rigorous testing of physiological countermeasures; however, all models have their strengths and limits. The 6

  1. Prior head-down tilt does not impair the cerebrovascular response to head-up tilt

    PubMed Central

    Yang, Changbin; Gao, Yuan; Greaves, Danielle K.; Villar, Rodrigo; Beltrame, Thomas; Fraser, Katelyn S.

    2015-01-01

    The hypothesis that cerebrovascular autoregulation was not impaired during head-up tilt (HUT) that followed brief exposures to varying degrees of prior head-down tilt (HDT) was tested in 10 healthy young men and women. Cerebral mean flow velocity (MFV) and cardiovascular responses were measured in transitions to a 60-s period of 75° HUT that followed supine rest (control) or 15 s HDT at −10°, −25°, and −55°. During HDT, heart rate (HR) was reduced for −25° and −55°, and cardiac output was lower at −55° HDT. MFV increased during −10° HDT, but not in the other conditions even though blood pressure at the middle cerebral artery (BPMCA) increased. On the transition to HUT, HR increased only for −55° condition, but stroke volume and cardiac output transiently increased for −25° and −55°. Total peripheral resistance index decreased in proportion to the magnitude of HDT and recovered over the first 20 s of HUT. MFV was significantly less in all HDT conditions compared with the control in the first 5-s period of HUT, but it recovered quickly. An autoregulation correction index derived from MFV recovery relative to BPMCA decline revealed a delay in the first 5 s for prior HDT compared with control but then a rapid increase to briefly exceed control after −55° HDT. This study showed that cerebrovascular autoregulation is modified by but not impaired by brief HDT prior to HUT and that cerebral MFV recovered quickly and more rapidly than arterial blood pressure to protect against cerebral hypoperfusion and potential syncope. PMID:25749443

  2. Use of bed rest and head-down tilt to simulate spaceflight-induce immune system changes

    NASA Technical Reports Server (NTRS)

    Schmitt, D. A.; Schaffar, L.; Taylor, G. R.; Loftin, K. C.; Schneider, V. S.; Koebel, A.; Abbal, M.; Sonnenfeld, G.; Lewis, D. E.; Reuben, J. R.; Ferebee, R.

    1996-01-01

    Bed rest, both with and without head-down tilt, has been extensively used as an earth-bound analog to study physiologic effects mimicking those occurring in weightlessness during spaceflight. We have been able to show in six subjects that 4 weeks of head-down tilt bed rest induces a significant decrease in interleukin-2 secretion by PHA-stimulated T lymphocytes. Another study, lasting 113 days, with two subjects showed a decreased interleukin-2 receptor expression in PHA-stimulated peripheral blood mononuclear cells but a decreased interleukin-2 production in one subject only. Under the same conditions, interleukin-1 production was largely increased in both subjects. Several other immune parameters were also analyzed. Increased interleukin-1 production could contribute to bone mineral loss encountered during bed rest and decreased interleukin-2 secretion could play a role in the appearance of infectious diseases often observed during bed red.

  3. Influence of long-term head-down body position on innervation density in extremity blood vessels

    NASA Technical Reports Server (NTRS)

    Lorant, M.; Raffai, G.; Nadasy, G.; Feher, E.; Monos, E.

    2001-01-01

    The aim of the present study was to quantitate and compare the density of nerve terminals (NTD), as well as of their synaptic vesicle population (SyVD) in saphenous and brachial vein and artery, obtained from rats maintained in the horizontal or head-down tilted (HDT) position for two weeks. The same technique was applied as that for the head-up tilt study.

  4. Head-Down Suspension Alters Stress-Responsiveness and Feedback Efficacy of 9a-Fludrocortisone in Rats

    NASA Technical Reports Server (NTRS)

    Horsley, C. J.; Evans, J.; Scribner, K. A.; Keil, L. C.; Dallman, M. F.

    1994-01-01

    9a-Fludrocortisone (9aFF) has been used to decrease orthostatic hypotension in astronauts whorl they return to earth after space flight. An earth-based model for weightlessness in space is head-down posture in man and rats. In these studies male rats were suspended head-down or not for 7 days and treated 14 and 2 hours prior to ether stress in the AM with 9aFF (20 micrograms i.u.) at -14 and -2 h or at -2 h with steroid and at -14 h with oil; controls were treated 2x with oil. Rats were decapitated 10 min after ether and ACTH and corticosterone (B) were measured. Both ACTH and B responses were greater in suspended than control rats under all three steroid conditions, and the percentage inhibition of ACTH by 9aFF was similar. Basal activity in the HPA over the 7 d suspension period was probably not elevated since adrenal and thymus weights did not differ in the ambulatory and head down groups. We conclude that headdown suspension facilitates acute stress-induced activity in the HPA axis, but that HPA axis sensitivity to corticosteroid feedback does not change.

  5. Focal Gray Matter Plasticity as a Function of Long Duration Head-down Tilt Bed Rest

    NASA Technical Reports Server (NTRS)

    Koppelmans, V.; DeDios, Y. E.; Wood, S. J.; Reuter-Lorenz, P. A.; Kofman, I.; Bloomberg, J. J.; Mulavara, A. P.; Koppelmans, V.

    2014-01-01

    Long duration spaceflight (i.e., > or = 22 days) has been associated with changes in sensorimotor systems, resulting in difficulties that astronauts experience with posture control, locomotion, and manual control. The microgravity environment is an important causal factor for spaceflight induced sensorimotor changes. Whether these sensorimotor changes may be related to structural and functional brain changes is yet unknown. However, experimental studies revealed changes in the gray matter (GM) of the brain after simulated microgravity. Thus, it is possible that spaceflight may affect brain structure and thereby cognitive functioning and motor behavior. Long duration head-down tilt bed rest has been suggested as an exclusionary analog to study microgravity effects on the sensorimotor system. Bed rest mimics microgravity in body unloading and bodily fluid shifts. In consideration of the health and performance of crewmembers both in- and post-flight, we are conducting a prospective longitudinal 70-day bed rest study as an analog to investigate the effects of microgravity on the brain. VBM analysis revealed a progressive decrease from pre- to in- bed rest in GM volume in bilateral areas including the frontal medial cortex, the insular cortex and the caudate. Over the same time period, there was a progressive increase in GM volume in the cerebellum, occipital-, and parietal cortex, including the precuneus. The majority of these changes did not fully recover during the post-bed rest period. Analysis of lobular GM volumes obtained with BRAINS showed significantly increased volume from pre-bed rest to in-bed rest in GM of the parietal lobe and the third ventricle. Temporal GM volume at 70 days in bed rest was smaller than that at the first pre-bed rest measurement. Trend analysis showed significant positive linear and negative quadratic relationships between parietal GM and time, a positive linear relationship between third ventricle volume and time, and a negative linear

  6. The metabolic reactions in men and women during long-term head-down tilt

    NASA Astrophysics Data System (ADS)

    Markin, Andrey

    We have demonstrated that dynamics of alterations of some biochemical blood indices during ling-term space flights and at a long duration head-down tilt (HDT) features that same directionality [Andrei Markin, Lubov Strogonova, Oleg Balashov et al, 1998]. A comparison between biochemical blood parameters at 120-day HDT was provided for groups consisting of nine men (MG1),six men (MG2) and four women (WG). All examined persons aged were exposed to "pure" HDT without resort to any prophylactic agents. Under investigations were concentrations of urea, uric acid, total cholesterol [CHO], HDL-cholesterol [HDL], triglycerides (TG), primary lipid peroxidation (LPO) products, final LPO products, tocopherol (TP) as well as activity of alanin aminotransferase (ALT), total creatin kinase (CK). For all the groups the investigated indices values were expressed as a percentage to background ones. ALT activity for the WG group had a tendency to decrease by 2-15 Women presented a moderate urea concentration lowering which ranged from 99 to 86 CHO level in WG was also elevated, and the extent to which elevated, for the most part, exceeded that of men, but beginning with the 72-nd - 84-th days of HDT an increase in MG1 become more pronounced with its retaining up to the RP. In all groups the tendency for decrease in HDL content was observed, however, it was more pronounced with men. In the RP the parameter value was increased in MG1 and MG2, but in WG it remained at the level which was observed at HDT. TG concentration women presented in the course of HDT increased, but beginning with the 49-th - 50-th day of experiment an increased in MG1 and MG2 became more pronounced. LPO products content dynamics in WG manifested as alternating increases and decreases relative to the background values (65 to 24 Comparative results of biochemical value dynamics investigation obtained in the course of a 120- day HDT demonstrated that women feature slower and less pronounced formation of metabolic

  7. Experimental aerodynamic characteristics for slender bodies with thin wings and tail at angles of attack from 0 deg to 58 deg and Mach numbers from 0.6 to 2.0

    NASA Technical Reports Server (NTRS)

    Jorgensen, L. H.; Nelson, E. R.

    1976-01-01

    An experimental investigation was conducted by wind tunnel to measure the static aerodynamic characteristics for bodies of circular and elliptic cross section with various thin flat plate wings and a thin tail consisting of horizontal and vertical parts. The wings had aspect ratios of 4 and taper ratios of about 0, 0.25, and 0.5. Two additional wings, which had taper ratios near 0.25 and aspect ratios of about 3 and 5, were also tested in combination with the bodies and tail. All wings had about the same planform area. The exposed area of the horizontal portion of the tail was about 33 to 36 percent of the exposed area of the wings. The exposed area of the vertical tail fin was about 22 to 24 percent of the exposed area of the wings. The elliptic body, with an a/b = 2 cross section, had the same length and axial distribution of cross sectional area as the circular body. The circular body had a cylindrical aftersection of fineness ratio 7, and it was tested with the wings and tail in combination with tangent ogive noses that had fineness ratios of 2.5, 3.0, 3.5, and 5.0. In addition, an ogive nose with a rounded tip and an ogive nose with two different nose strake arrangements were used. Nineteen configuration combinations were tested at Mach numbers of 0.6, 0.9, 1.5, and 2.0 at angles of attack from 0 to 58 deg. The Reynolds numbers, based on body base diameter, were about 4.3 X 100,000.

  8. Changes of loading tensile force-stretch relationships of rabbit mesenteric vein after 21 days of head-down rest

    NASA Astrophysics Data System (ADS)

    Yao, Yong-Jie; Sun, Hui-Pin; Yue, Yong; Sun, Xi-Qing; Wu, Xing-Yu

    Changes of venous compliance may contribute to postflight orthostatic intolerance; however, direct animal studies to address the changes of venous compliance to microgravity have been rare. The purpose of this study was to determine compliance changes of mesenteric veins of rabbits after 21 days of head-down rest (HDR). Twenty-four healthy male New Zealand Rabbits were randomly divided into 21 days of HDR group, horizontal immobilization group (HIG) and control group (Ctrl), with eight in each. Loading tensile force-stretch relationships of mesenteric vein segments were constructed after 21 d HDR. With the increase of loading tensile force, both longitudinal and circumferential stretches of vein samples increased significantly. Under the same loading tensile force, mesenteric vein of the HDR showed significant increase both in circumferential stretch and longitudinal stretches compared to those of Ctrl group and HIG group. These results indicate that, a 21-day simulated weightlessness leads to increase of mesenteric venous compliance.

  9. [Evaluation of effectiveness of short-term orthostatic positioning of head-down tilted primates on the liquid body sectors].

    PubMed

    Lobachik, V I; Gordeev, Iu V; Krotov, V P

    2008-01-01

    Head-down tilting (HDT) of primates is a well-recognized model for studying the hypokinetic syndrome effects on the body functions. Benefits for the body liquids distribution of periodic transition of primates (rhesus macaques) into the vertical position without support loading were evaluated in a 30-d HDT experiment. Brief (30 to 120 minutes long, 4-5 times a week) transition from tilting into the vertical position had no influence on primates' hydration homeostasis and its infrastructure. However, the orthostatic test at the end of the HDT experiment showed a less increase in blood content of the lower extremities as compared with tilted primates that had not been periodically turned up into the vertical position. PMID:18714731

  10. Effects of 17 days of head-down bed rest on hydro-electrolytic regulation in men

    NASA Technical Reports Server (NTRS)

    Millet, C.; Custaud, M. A.; Allevard, A. M.; Zaouali-Ajina, M.; Monk, T. H.; Arnaud, S. B.; Gharib, C.; Gauquelin-Koch, G.

    2001-01-01

    Prolonged periods of head-down bed rest (HDBR) are commonly used to mimic the effects of microgravity. HDBR has been shown to produce, as in space, a cephalad redistribution of circulating blood volume with an increase in central blood volume which induces the early adaptations in blood volume regulating hormones. Changes in atrial natriuretic peptide (ANP), arginine vasopressin (AVP), renin activity and aldosterone have been observed. Many reports describe these endocrine adaptations but few investigations of rhythms are in the literature. We proposed to evaluate the circadian rhythms of the hormones and electrolytes involved in the hydro-electrolytic regulation during a HDBR study which was designed to simulate a 17-day spaceflight (Life and Microgravity Spacelab experiment, LMS, NASA).

  11. Computer simulation of the effect of dDAVP with saline loading on fluid balance after 24-hour head-down tilt

    NASA Technical Reports Server (NTRS)

    Srinivasan, R. S.; Simanonok, K. E.; Charles, J. B.

    1994-01-01

    Fluid loading (FL) before Shuttle reentry is a countermeasure currently in use by NASA to improve the orthostatic tolerance of astronauts during reentry and postflight. The fluid load consists of water and salt tablets equivalent to 32 oz (946 ml) of isotonic saline. However, the effectiveness of this countermeasure has been observed to decrease with the duration of spaceflight. The countermeasure's effectiveness may be improved by enhancing fluid retention using analogs of vasopressin such as lypressin (LVP) and desmopressin (dDAVP). In a computer simulation study reported previously, we attempted to assess the improvement in fluid retention obtained by the use of LVP administered before FL. The present study is concerned with the use of dDAVP. In a recent 24-hour, 6 degree head-down tilt (HDT) study involving seven men, dDAVP was found to improve orthostatic tolerance as assessed by both lower body negative pressure (LBNP) and stand tests. The treatment restored Luft's cumulative stress index (cumulative product of magnitude and duration of LBNP) to nearly pre-bedrest level. The heart rate was lower and stroke volume was marginally higher at the same LBNP levels with administration of dDAVP compared to placebo. Lower heart rates were also observed with dDAVP during stand test, despite the lower level of cardiovascular stress. These improvements were seen with only a small but significant increase in plasma volume of approximately 3 percent. This paper presents a computer simulation analysis of some of the results of this HDT study.

  12. The implementation of game in a 20-day head-down tilting bed rest experiment upon mood status and neurotic levels of rest subjects

    NASA Astrophysics Data System (ADS)

    Ishizaki, Yuko; Fukuoka, Hideoki; Ishizaki, Tatsuro; Tanaka, Hidetaka; Ishitobi, Hiromi

    2004-12-01

    This study evaluated the effect of the implementation of game on mental health among participants in a bed rest (BR) experiment. Subjects were 12 healthy males aged 20-26, who participated in a 20-day 6-degrees head-down tilting BR experiment. The participants were asked to complete psychometrical questionnaires before, during, and after the experiment. We entrusted the participants to manage their leisure time and they intended a game in which all of them could take part over the experiment period. The general conversation and light-hearted mood among the subjects continued during the experimental period. Longitudinal data analysis showed that levels of neurosis and mood status did not deteriorate during the experiment, while our previous experiments, which were performed under the same protocol as this study except for the implementation of the game showed a distinct deterioration in psychosocial status. We consider that the implementation of game autonomously contributes to the positive effects on the mental health among the participants.

  13. Effects of Mild Hypercapnia During Head-Down Bed Rest on Ocular Structures, Cerebral Blood Flow, aud Visual Acuity in Healthy Human Subjects

    NASA Technical Reports Server (NTRS)

    Laurie, S. S.; Taibbi, G.; Lee, S. M. C.; Martin, D. S.; Zanello, S.; Ploutz-Snyder, R.; Hu, X.; Stenger, M. B.; Vizzeri, G.

    2014-01-01

    The cephalad fluid shift induced by microgravity has been hypothesized to cause an elevation in intracranial pressure (ICP) and contribute to the development of the Visual Impairment/Intracranial Pressure (VIIP) syndrome, as experienced by some astronauts during long-duration space flight. Elevated ambient partial pressure of carbon dioxide (PCO2) on ISS may also raise ICP and contribute to VIIP development. We seek to determine if the combination of mild CO2 exposure, similar to that occurring on the International Space Station, with the cephalad fluid shift induced by head-down tilt, will induce ophthalmic and cerebral blood flow changes similar to those described in the VIIP syndrome. We hypothesize that mild hypercapnia in the head-down tilt position will increase choroidal blood volume and cerebral blood flow, raise intraocular pressure (IOP), and transiently reduce visual acuity as compared to the seated or the head-down tilt position without elevated CO2, respectively.

  14. Experimental and predicted cavitation performance of an 80.6 deg helical inducer in high temperature water

    NASA Technical Reports Server (NTRS)

    Kovich, G.

    1972-01-01

    The cavitating performance of a stainless steel 80.6 degree flat-plate helical inducer was investigated in water over a range of liquid temperatures and flow coefficients. A semi-empirical prediction method was used to compare predicted values of required net positive suction head in water with experimental values obtained in water. Good agreement was obtained between predicted and experimental data in water. The required net positive suction head in water decreased with increasing temperature and increased with flow coefficient, similar to that observed for a like inducer in liquid hydrogen.

  15. Effects of long-term head-down-tilt bed rest and different training regimes on the coagulation system of healthy men

    PubMed Central

    Haider, Thomas; Gunga, Hanns-Christian; Matteucci-Gothe, Raffaella; Sottara, Elke; Griesmacher, Andrea; Belavý, Daniel L; Felsenberg, Dieter; Werner, Andreas; Schobersberger, Wolfgang

    2013-01-01

    Immobility plus preexisting chronic disease or acute trauma can activate the coagulation system, thus increasing the risk for thromboembolic events. The effects of long-term bed-rest immobility and microgravity on the coagulation system of healthy persons (e.g., during crewed Mars missions) have not yet been studied. The main objective of the second Berlin BedRest Study (BBR2-2) “Coagulation Part” was to investigate adaptations of the hemostatic system during long-term bed rest (60 days) under simulated microgravity (6° head-down-tilt [6°HDT]) and after mobilization in three different volunteer groups (randomly assigned to CTR= inactive control group; RE= resistive exercise only group; and RVE= resistive exercise with whole-body vibration group). In 24 males (aged 21–45 years), before, during, and after long-term bed rest, key parameters of coagulation were measured from venous blood samples: D-dimer (DD), thrombin–antithrombin III complex (TAT), and prothrombin fragment F1 + 2 (PT-F1 + 2). Additionally, modified rotational thrombelastometry (ROTEM®) analysis was performed. Times of exploratory analyses were as follows: baseline data collection 2 days before bed rest (BDC-2); eight different days of 6°HDT bed rest (HDT1–HDT60), and two different days after reambulation (R + 3 and R + 6). We found significant changes in DD, TAT, and PT-F1 + 2 over the total time course, but no consistent effect of physical interventions (RE, RVE) on these parameters. Notably, no parameter reached levels indicative of intravascular thrombin formation. All ROTEM® parameters remained within the normal range and no pathological traces were found. Sixty days of 6°HDT bed rest are not associated with pronounced activation of the coagulation system indicative of intravascular thrombus formation in healthy volunteers independent of the training type during the bed rest. PMID:24400137

  16. Efficacy of periodic centrifugation of primates during 4-week head-down tilt

    NASA Astrophysics Data System (ADS)

    Korolkov, V. I.; Kozlovskaya, I. B.; Kotovskaya, A. R.; Krotov, V. P.; Vil-Viliams, I. F.; Lobachik, V. I.

    2001-08-01

    Creation of artificial force of gravity (AFG) to counteract the negative consequences of microgravity in manned space missions of extended duration is one of the high-priority problems of space biology and medicine. However, there are a number of especial effects of AFG (namely, structural changes in muscles and bones, and some other system) which need implantation of electrodes and sensors and are possible only with animals. That is why it is of particular interest to make studies with monkeys whose reactions to changed gravity bear much resemblance with human (1). The purpose of the investigation was development of a protocol of periodic gravity loads as a countermeasure against the hypokinetic syndrome in Macaca mulatta. Two series of experiments were performed. In the series, animals were split into two groups of 6 species each who were motor restrained with the head end tilted downward at 5° (HDT) for 28 days. Monkeys of group-2 were periodically subjected to centrifugation (HDT+G). During the first series of experiments rotation was conducted in the +Gz direction at g-loads from 1.2 to 1.6 units for 30-40 minutes 4-5 times a week. In the second series, g-load was equal to 1.2 units and the animals were rotated 30 min. 2-3 time a week. The criterion of g-training protocol efficacy was a test +Gz run at 3 units for 30 s. during which functioning of the cardiovascular systems and its controls was evaluated. The test run was performed prior to and after HDT. Following HDT the animals of group HDT+G were more resistant to the test than their counterparts who had not been trained on the centrifuge. Data of the investigation imply that following HDT and HDT+G alike reduced the amount of total bodily fluids (by approximately 5%), the intracellular component (approximately 4%), and plasma volume (by 6-7%). Yet, there are radical differences between the groups in the levels of reduction in extracellular fluids (by 11% and 6.5%, respectively, P<0,05) and the

  17. Experimental Determination of the Recovery Factor and Analytical Solution of the Conical Flow Field for a 20 deg Included Angle Cone at Mach Numbers of 4.6 and 6.0 and Stagnation Temperatures to 2600 degree R

    NASA Technical Reports Server (NTRS)

    Pfyl, Frank A.; Presley, Leroy L.

    1961-01-01

    The local recovery factor was determined experimentally along the surface of a thin-walled 20 deg included angle cone for Mach numbers near 6.0 at stagnation temperatures between 1200 deg R and 2600 deg R. In addition, a similar cone configuration was tested at Mach numbers near 4.5 at stagnation temperatures of approximately 612 deg R. The local Reynolds number based on flow properties at the edge of the boundary layer ranged between 0.1 x 10(exp 4) and 3.5 x 10(exp 4) for tests at temperatures above 1200 deg R and between 6 x 10(exp 4) and 25 x 10(exp 4) for tests at temperatures near 612 deg R. The results indicated, generally, that the recovery factor can be predicted satisfactorily using the square root of the Prandtl number. No conclusion could be made as to the necessity of evaluating the Prandtl number at a reference temperature given by an empirical equation, as opposed to evaluating the Prandtl number at the wall temperature or static temperature of the gas at the cone surface. For the tests at temperatures above 1200 deg R (indicated herein as the tests conducted in the slip-flow region), two definite trends in the recovery data were observed - one of increasing recovery factor with decreasing stagnation pressure, which was associated with slip-flow effects and one of decreasing recovery factor with increasing temperature. The true cause of the latter trend could not be ascertained, but it was shown that this trend was not appreciably altered by the sources of error of the magnitude considered herein. The real-gas equations of state were used to determine accurately the local stream properties at the outer edge of the boundary layer of the cone. Included in the report, therefore, is a general solution for the conical flow of a real gas using the Beattie-Bridgeman equation of state. The largest effect of temperature was seen to be in the terms which were dependent upon the internal energy of the gas. The pressure and hence the pressure drag terms were

  18. Experimental aerodynamic performance of advanced 40 deg-swept 10-blade propeller model at Mach 0.6 to 0.85

    NASA Technical Reports Server (NTRS)

    Mitchell, Glenn A.

    1988-01-01

    A propeller designated as SR-6, designed with 40 deg of sweep and 10 blades to cruise at Mach 0.8 at an altitude of 10.7 km (35,000 ft), was tested in the NASA Lewis Research Center's 8- by 6-Foot Wind Tunnel. This propeller was one of a series of advanced single rotation propeller models designed and tested as part of the NASA Advanced Turboprop Project. Design-point net efficiency was almost constant to Mach 0.75 but fell above this speed more rapidly than that of any previously tested advanced propeller. Alternative spinners that further reduced the near-hub interblade Mach numbers and relieved the observed hub choking improved performance above Mach 0.75. One spinner attained estimated SR-6 Design-point net deficiencies of 80.6 percent at Mach 0.75 and 79.2 percent at Mach 0.8, higher than the measured performance of any previously tested advanced single-rotation propeller at these speeds.

  19. Countermeasures and Functional Testing in Head-Down Tilt Bed Rest (CFT 70)

    NASA Technical Reports Server (NTRS)

    Cromwell, Ronita L.

    2013-01-01

    This 70-day bed rest campaign was comprised of 6 integrated studies and conducted at the NASA Flight Analogs Research Unit (FARU). The FARU is located at the University of Texas Medical Branch, Galveston, Texas and is a satellite unit of the Institute for Translational Sciences - Clinical Research Center. This presentation will describe the FARU, discuss the utility of the bed rest platform for use in these studies, and introduce the studies that participated in the CFT 70 bed rest campaign. Information in this presentation will serve as the background for subsequent talks from each individual study. Individual study presentations will discuss preliminary results from completed subjects. Studies included in CFT70 were: ? Physiological Factors Contributing to Post Flight Changes in Functional Performance. J. Bloomberg, NASA ? Integrated Resistance and Aerobic Training Study. L. Ploutz-Snyder, USRA ? Testosterone Supplementation as a Countermeasure Against Musculoskeletal losses during Space Exploration. R. Urban, University of Texas Medical Branch ? Effects of Retronasal Smelling, Variety and Choice on Appetite & Satiety. J. Hunter, Cornell University ? AD ASTRA: Automated Detection of Attitudes and States through Transaction Recordings Analysis. C. Miller, Smart Information Flow Technologies, LLC ? Bed Rest as a Spaceflight Analog to Study Neuro-cognitive Changes: Extent, Longevity, and Neural Bases. R. Seidler, University of Michigan

  20. Performance and mood-state parameters during 30-day 6 degrees head-down bed rest with exercise training

    NASA Technical Reports Server (NTRS)

    DeRoshia, C. W.; Greenleaf, J. E.

    1993-01-01

    The study was designed to determine if performance and mood impairments occur in bed-rested subjects, and if different exercise-training regimens modify or prevent them. Eighteen normal, healthy men were divided on the basis of age, peak oxygen uptake, and maximal isometric knee extension strength into three similar groups: no exercise (NOE), isotonic exercise (ITE), and isokinetic exercise (IKE). A 15-min battery of 10 performance tests and 8 mood and 2 sleep scales were administered daily during ambulatory control, 30 d of absolute bed rest (BR), and 4 d of ambulatory recovery. Performance test proficiency increased (p < 0.05) for all three groups during BR in 7 of 10 tests and there were no consistent significant differences between the three groups. However, during BR, the ITE group was distinguished from the other groups by a decline (p < 0.05) in the activation mood dimension and in two of its constituent scales (motivation and concentration), and by improvement (p < 0.05) in the trouble-falling-asleep and psychological-tension scales. Since few deleterious changes in performance and mood occurred in the three groups and did not exceed baseline ambulatory levels, we conclude that mood and performance did not deteriorate in response to prolonged BR and were not altered by exercise training. However, the decline in activation mood scales in the ITE group may reflect overtraining or excess total workload in this group.

  1. Isokinetic strength and endurance during 30-day 6 degrees head-down bed rest with isotonic and isokinetic exercise training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Bernauer, E. M.; Ertl, A. C.; Bulbulian, R.; Bond, M.

    1994-01-01

    The purpose of our study was to determine if an intensive, intermittent, isokinetic, lower extremity exercise training program would attenuate or eliminate the decrease of muscular strength and endurance during prolonged bed rest (BR). The 19 male subjects (36 +/- 1 yr, 178 +/- 2 cm, 76.5 +/- 1.7 kg) were allocated into a no exercise (NOE) training group (N = 5), an isotonic (lower extremity cycle ergometer) exercise (ITE) training group (N = 7), and an isokinetic (isokinetic knee flexion-extension) exercise (IKE) training group (N = 7). Peak knee (flexion and extension) and shoulder (abduction-adduction) functions were measured weekly in all groups with one 5-repetition set. After BR, average knee extension total work decreased by 16% with NOE, increased by 27% with IKE, and was unchanged with ITE. Average knee flexion total work and peak torque (strength) responses were unchanged in all groups. Force production increased by 20% with IKE and was unchanged with NOE and ITE. Shoulder total work was unchanged in all groups, while gross average peak torque increased by 27% with ITE and by 22% with IKE, and was unchanged with NOE. Thus, while ITE training can maintain some isokinetic functions during BR, maximal intermittent IKE training can increase other functions above pre-BR control levels.

  2. High dietary sodium chloride causes further protein loss during head-down tilt bed rest (HDBR)

    NASA Astrophysics Data System (ADS)

    Buehlmeier, Judith; Frings-Meuthen, Petra; Baecker, Natalie; Stehle, Peter; Heer, Martina

    Human spaceflight is associated with a loss of body protein most likely caused by muscle degradation. Additionally astronauts tend towards a high dietary intake of sodium chloride (NaCl), which has recently been shown to induce low grade metabolic acidosis (Frings-Meuthen et al. JBMR, Epub 2007). In several patterns, e.g. chronical renal failure, metabolic acidosis is associated with protein catabolism. We therefore hypothesized that high dietary intake of NaCl enforces protein losses in HDBR, a model for physiological changes in microgravity (µG). Eight healthy male subjects (mean age 26.25 ± 3.5; mean body weight: 78.5 ± 4.1 kg) participated in a 14-day bed rest study in the metabolic ward of the DLR - Institute of Aerospace Medicine, Cologne, Germany. The study was carried out in a cross over design, consisting of two phases, each lasting 22 days (5 days adaptation, 14 days 6° HDBR and 3 days recovery). Both study phases were identical with respect to environmental conditions and study protocol. Subjects received an individually tailored, weight-maintaining diet containing 1.3 g protein/kg/day. The diet was identical in both study phases with the exception of NaClintake: Every subject received a low NaCl diet (0.7 mmol/kg/day) in one phase and a high NaCl diet (7.7 mmol/kg/day) in another one. Blood gas for analysis of acid-base balance was implemented at days 4 and 5 of adaptation, days 2, 5, 7, 10, 12, 14 of HDBR and days 2, 3 of recovery. Continuous urine collection started on the first day in the metabolic ward to analyze nitrogen excretion. Nitrogen balance was calculated from the difference between protein intake and urinary nitrogen excretion, determined by use of chemiluminescence (Grimble et al. JPEN, 1988). Plasma pH did not change significantly (p=0.285), but plasma bicarbonate and base excess decreased (p=0.0175; p=0.0093) with high NaCl intake in HDBR compared to the low NaCl diet. Nitrogen balance in HDBR was negative, as expected in

  3. Electromyography-based analysis of human upper limbs during 45-day head-down bed-rest

    NASA Astrophysics Data System (ADS)

    Fu, Anshuang; Wang, Chunhui; Qi, Hongzhi; Li, Fan; Wang, Zheng; He, Feng; Zhou, Peng; Chen, Shanguang; Ming, Dong

    2016-03-01

    Muscle deconditioning occurs in response to simulated or actual microgravity. In spaceflight, astronauts become monkey-like for mainly using their upper limbs to control the operating system and to complete corresponding tasks. The changes of upper limbs' athletic ability will directly affect astronauts' working performance. This study investigated the variation trend of surface electromyography (sEMG) during prolonged simulated microgravity. Eight healthy males participating in this study performed strict 45-day head-down bed-rest (HDBR). On the 5th day of pre-HDBR, and the 15th, the 30th and the 45th days of HDBR, the subjects performed maximum pushing task and maximum pulling task, and sEMG was collected from upper limbs synchronously. Each subject's maximum volunteer contractions of both the tasks during these days were compared, showing no significant change. However, changes were detected by sEMG-based analysis. It was found that integrated EMG, root mean square, mean frequency, fuzzy entropy of deltoid, and fuzzy entropy of triceps brachii changed significantly when comparing pre-HDBR with HDBR. The variation trend showed a recovery tendency after significant decline, which is inconsistent with the monotonic variation of lower limbs that was proved by previous research. These findings suggest that EMG changes in upper limbs during prolonged simulated microgravity, but has different variation trend from lower limbs.

  4. Orthostatic Intolerance Is Independent of the Degree of Autonomic Cardiovascular Adaptation after 60 Days of Head-Down Bed Rest.

    PubMed

    Liu, Jiexin; Li, Yongzhi; Verheyden, Bart; Chen, Zhanghuang; Wang, Jingyu; Li, Yinghui; Aubert, André E; Yuan, Ming

    2015-01-01

    Spaceflight and head-down bed rest (HDBR) can induce the orthostatic intolerance (OI); the mechanisms remain to be clarified. The aim of this study was to determine whether or not OI after HDBR relates to the degree of autonomic cardiovascular adaptation. Fourteen volunteers were enrolled for 60 days of HDBR. A head-up tilt test (HUTT) was performed before and after HDBR. Our data revealed that, in all nonfainters, there was a progressive increase in heart rate over the course of HDBR, which remained higher until 12 days of recovery. The mean arterial pressure gradually increased until day 56 of HDBR and returned to baseline after 12 days of recovery. Respiratory sinus arrhythmia and baroreflex sensitivity decreased during HDBR and remained suppressed until 12 days of recovery. Low-frequency power of systolic arterial pressure increased during HDBR and remained elevated during recovery. Three subjects fainted during the HUTT after HDBR, in which systemic vascular resistance did not increase and remained lower until syncope. None of the circulatory patterns significantly differed between the fainters and the nonfainters at any time point. In conclusion, our data indicate that the impaired orthostatic tolerance after HDBR could not be distinguished by estimation of normal hemodynamic and/or neurocardiac data. PMID:26425559

  5. Orthostatic Intolerance Is Independent of the Degree of Autonomic Cardiovascular Adaptation after 60 Days of Head-Down Bed Rest

    PubMed Central

    Liu, Jiexin; Li, Yongzhi; Verheyden, Bart; Chen, Zhanghuang; Wang, Jingyu; Li, Yinghui; Aubert, André E.; Yuan, Ming

    2015-01-01

    Spaceflight and head-down bed rest (HDBR) can induce the orthostatic intolerance (OI); the mechanisms remain to be clarified. The aim of this study was to determine whether or not OI after HDBR relates to the degree of autonomic cardiovascular adaptation. Fourteen volunteers were enrolled for 60 days of HDBR. A head-up tilt test (HUTT) was performed before and after HDBR. Our data revealed that, in all nonfainters, there was a progressive increase in heart rate over the course of HDBR, which remained higher until 12 days of recovery. The mean arterial pressure gradually increased until day 56 of HDBR and returned to baseline after 12 days of recovery. Respiratory sinus arrhythmia and baroreflex sensitivity decreased during HDBR and remained suppressed until 12 days of recovery. Low-frequency power of systolic arterial pressure increased during HDBR and remained elevated during recovery. Three subjects fainted during the HUTT after HDBR, in which systemic vascular resistance did not increase and remained lower until syncope. None of the circulatory patterns significantly differed between the fainters and the nonfainters at any time point. In conclusion, our data indicate that the impaired orthostatic tolerance after HDBR could not be distinguished by estimation of normal hemodynamic and/or neurocardiac data. PMID:26425559

  6. Effects of short-term exposure to head-down tilt on cerebral hemodynamics: a prospective evaluation of a spaceflight analog using phase-contrast MRI.

    PubMed

    Marshall-Goebel, Karina; Ambarki, Khalid; Eklund, Anders; Malm, Jan; Mulder, Edwin; Gerlach, Darius; Bershad, Eric; Rittweger, Jörn

    2016-06-15

    Alterations in cerebral hemodynamics in microgravity are hypothesized to occur during spaceflight and could be linked to the Visual Impairment and Intracranial Pressure syndrome. Head-down tilt (HDT) is frequently used as a ground-based analog to simulate cephalad fluid shifts in microgravity; however, its effects on cerebral hemodynamics have not been well studied with MRI techniques. Here, we evaluate the effects of 1) various HDT angles on cerebral arterial and venous hemodynamics; and 2) exposure to 1% CO2 during an intermediate HDT angle (-12°) as an additional space-related environmental factor. Blood flow, cross-sectional area (CSA), and blood flow velocity were measured with phase-contrast MRI in the internal jugular veins, as well as the vertebral and internal carotid arteries. Nine healthy male subjects were measured at baseline (supine, 0°) and after 4.5 h of HDT at -6°, -12° (with and without 1% CO2), and -18°. We found a decrease in total arterial blood flow from baseline during all angles of HDT. On the venous side, CSA increased with HDT, and outflow decreased during -12° HDT (P = 0.039). Moreover, the addition of 1% CO2 to -12° HDT caused an increase in total arterial blood flow (P = 0.016) and jugular venous outflow (P < 0.001) compared with -12° HDT with ambient atmosphere. Overall, the results indicate decreased cerebral blood flow during HDT, which may have implications for microgravity-induced cerebral hemodynamic changes. PMID:27013606

  7. Effects of short-term exposure to head-down tilt on cerebral hemodynamics: a prospective evaluation of a spaceflight analog using phase-contrast MRI

    PubMed Central

    Ambarki, Khalid; Eklund, Anders; Malm, Jan; Mulder, Edwin; Gerlach, Darius; Rittweger, Jörn

    2016-01-01

    Alterations in cerebral hemodynamics in microgravity are hypothesized to occur during spaceflight and could be linked to the Visual Impairment and Intracranial Pressure syndrome. Head-down tilt (HDT) is frequently used as a ground-based analog to simulate cephalad fluid shifts in microgravity; however, its effects on cerebral hemodynamics have not been well studied with MRI techniques. Here, we evaluate the effects of 1) various HDT angles on cerebral arterial and venous hemodynamics; and 2) exposure to 1% CO2 during an intermediate HDT angle (−12°) as an additional space-related environmental factor. Blood flow, cross-sectional area (CSA), and blood flow velocity were measured with phase-contrast MRI in the internal jugular veins, as well as the vertebral and internal carotid arteries. Nine healthy male subjects were measured at baseline (supine, 0°) and after 4.5 h of HDT at −6°, −12° (with and without 1% CO2), and −18°. We found a decrease in total arterial blood flow from baseline during all angles of HDT. On the venous side, CSA increased with HDT, and outflow decreased during −12° HDT (P = 0.039). Moreover, the addition of 1% CO2 to −12° HDT caused an increase in total arterial blood flow (P = 0.016) and jugular venous outflow (P < 0.001) compared with −12° HDT with ambient atmosphere. Overall, the results indicate decreased cerebral blood flow during HDT, which may have implications for microgravity-induced cerebral hemodynamic changes. PMID:27013606

  8. The XMM-BCS galaxy cluster survey: I. The X-ray selected cluster catalog from the initial 6 deg$^2$

    SciTech Connect

    Suhada, R.; Song, J.; Bohringer, H.; Mohr, J.J.; Chon, G.; Finoguenov, A.; Fassbender, R.; Desai, S.; Armstrong, R.; Zenteno, A.; Barkhouse, W.A.; /North Dakota U. /Paris, Inst. Astrophys.

    2011-11-01

    The XMM-Newton - Blanco Cosmology Survey project (XMM-BCS) is a coordinated X-ray, optical and mid-infrared cluster survey in a field also covered by Sunyaev-Zel dovich effect (SZE) surveys by the South Pole Telescope and the Atacama Cosmology Telescope. The aim of the project is to study the cluster population in a 14 deg{sup 2} field (center: {alpha} {approx} 23:29:18.4, {delta} {approx} -54:40:33.6). The uniform multi-wavelength coverage will also allow us for the first time to comprehensively compare the selection function of the different cluster detection approaches in a single test field and perform a cross-calibration of cluster scaling relations. In this work, we present a catalog of 46 X-ray selected clusters from the initial 6 deg{sup 2} survey core.We describe the XMM-BCS source detection pipeline and derive physical properties of the clusters. We provide photometric redshift estimates derived from the BCS imaging data and spectroscopic redshift measurements for a low redshift subset of the clusters. The photometric redshift estimates are found to be unbiased and in good agreement with the spectroscopic values. Our multi-wavelength approach gives us a comprehensive look at the cluster and group population up to redshifts z {approx} 1. The median redshift of the sample is 0.47 and the median mass M{sub 500} {approx} 1 x 10{sup 14} M{sub {circle_dot}} ({approx} 2 keV). From the sample, we derive the cluster log N - log S using an approximation to the survey selection function and find it in good agreement with previous studies. We compare optical mass estimates from the Southern Cosmology Survey available for part of our cluster sample with our estimates derived from the X-ray luminosity. Weak lensing masses available for a subset of the cluster sample are in agreement with our estimates. Optical masses based on cluster richness and total optical luminosity are found to be significantly higher than the X-ray values. The present results illustrate the

  9. The Effects of Long Duration Head Down Tilt Bed Rest on Neurocognitive Performance: The Effects of Exercise Interventions

    NASA Technical Reports Server (NTRS)

    Seidler, R. D.; Mulavara, A. P.; Koppelmans, V.; Erdeniz. B.; Kofman, I. S.; DeDios, Y. E.; Szecsy, D. L.; Riascos-Castaneda, R. F.; Wood, S. J.; Bloomberg, J. J.

    2014-01-01

    We are conducting ongoing experiments in which we are performing structural and functional magnetic resonance brain imaging to identify the relationships between changes in neurocognitive function and neural structural alterations following a six month International Space Station mission and following 70 days exposure to a spaceflight analog, head down tilt bedrest. Our central hypothesis is that measures of brain structure, function, and network integrity will change from pre to post intervention (spaceflight, bedrest). Moreover, we predict that these changes will correlate with indices of cognitive, sensory, and motor function in a neuroanatomically selective fashion. Our interdisciplinary approach utilizes cutting edge neuroimaging techniques and a broad ranging battery of sensory, motor, and cognitive assessments that will be conducted pre flight, during flight, and post flight to investigate potential neuroplastic and maladaptive brain changes in crewmembers following long-duration spaceflight. Success in this endeavor would 1) result in identification of the underlying neural mechanisms and operational risks of spaceflight-induced changes in behavior, and 2) identify whether a return to normative behavioral function following re-adaptation to Earth's gravitational environment is associated with a restitution of brain structure and function or instead is supported by substitution with compensatory brain processes. Our ongoing bed rest participants are also engaging in exercise studies directed by Dr. Lori Ploutz Snyder. In this presentation, I will briefly highlight the existing literature linking exercise and fitness to brain and behavioral functions. I will also overview the metrics from my study that could be investigated in relation to the exercise and control subgroups.

  10. Lower-body negative pressure restores leg bone microvascular flow to supine levels during head-down tilt.

    PubMed

    Siamwala, Jamila H; Lee, Paul C; Macias, Brandon R; Hargens, Alan R

    2015-07-15

    Skeletal unloading and cephalic fluid shifts in microgravity may alter the bone microvascular flow and may be associated with the 1-2% bone loss per month during spaceflight. The purpose of this study was to determine if lower-body negative pressure (LBNP) can prevent microgravity-induced alterations of tibial microvascular flow. Head-down tilt (HDT) simulates the cephalad fluid shift and microvascular flow responses that may occur in microgravity. We hypothesized that LBNP prevents HDT-induced increases in tibial microvascular flow. Tibial bone microvascular flow, oxygenation, and calf circumference were measured during 5 min sitting, 5 min supine, 5 min 15° HDT, and 10 min 15° HDT with 25 mmHg LBNP using photoplethysmography (PPG), near-infrared spectroscopy (NIRS), and strain-gauge plethysmography (SGP). Measurements were made simultaneously. Tibial microvascular flow increased by 36% with 5 min 15° HDT [2.2 ± 1.1 V; repeated-measures ANOVA (RMANOVA) P < 0.0001] from supine (1.4 ± 0.8 V). After 10 min of LBNP in the 15° HDT position, tibial microvascular flow returned to supine levels (1.1 ± 0.5 V; RMANOVA P < 0.001). Tibial oxygenation did not change significantly during sitting, supine, HDT, or HDT with LBNP. However, calf circumference decreased with 5 min 15° HDT (-0.7 ± 0.4 V; RMANOVA P < 0.0001) from supine (-0.5 ± 0.4 V). However, with LBNP calf circumference returned to supine levels (-0.4 ± 0.1 V; RMANOVA P = 0.002). These data establish that simulated microgravity increases tibial microvascular flow and LBNP prevents these increases. The results suggest that LBNP may provide a suitable countermeasure to normalize the bone microvascular flow during spaceflight. PMID:25930022

  11. Gas-jet and tangent-slot film cooling tests of a 12.5 deg cone at Mach number of 6.7

    NASA Technical Reports Server (NTRS)

    Nowak, Robert J.

    1988-01-01

    Tests were conducted in the Langley 8-Foot High Temperature Tunnel to determine the aerothermal effects of gaseous nitrogen-coolant ejection on a 3-ft base-diameter, 12.5 degree half-angle cone. Free-stream Mach number, total temperature, and unit Reynolds number per foot were 6.7, 3300 deg R, and 1.4 million, respectively. Two coolant ejection noses were tested, an ogive frustum with a forward-facing 0.8-in radius gas-jet tip, and a 3-in radius hemisphere with a 0.243-in high rearward-facing tangent slot. Data include surface pressures and heating rates, shock shapes, and shock-layer profiles; results are compared with no-cooling data obtained with 1-in and 3-in radius solid noses. Surface pressures were reduced with gas-jet ejection but were affected little by tangent-slot ejection. For both gas-jet and tangent-slot ejection, high coolant flow rates reduced heating even far downstream from the region of ejection; however, low coolant rates caused transition to turbulence and increased heating. Shock-layer profiles of pitot pressure, Mach number, and total temperature were reduced for both gas-jet and tangent-slot ejection. Insight into the gas-jet heat-flux mechanisms was obtained by using shock-layer rake data and established, no-cooling, heat-transfer equations.

  12. Aerodynamic heating on the corrugated surface of a 10.2 deg half-angle blunted cone at Mach 6.7

    NASA Technical Reports Server (NTRS)

    Weinstein, I.; Avery, D. E.; Hunt, L. R.

    1981-01-01

    A 10.2 deg half-angle blunted cone with corrugated surfaces was tested in the Langley 8-foot high-temperature structures tunnel to measure the aerodynamic heating of its surfaces. The tests were made in a turbulent boundary layer at angles of attack of 0 deg, 5 deg, and 10 deg. Heating of the windward side was in reasonable agreement with theoretical turbulent predictions for a smooth cone, while heating on the leeward side was between laminar and turbulent predictions as a result of local transitional flow or flow separation produced by high lee-side pressures. Localized heating measurements indicated a significant increase in heating at large cross-flow angles, with the maximum heating rates occurring where the flow reattaches on the upstream side of the corrugation crest and the minimum occurring on the downstream side where the flow is separated.

  13. Aerodynamic Force Characteristics of a Series of Lifting Cone and Cone-Cylinder Configurations at a Mach Number of 6.83 and Angles of Attack up to 130 Deg

    NASA Technical Reports Server (NTRS)

    Penland, Jim A.

    1961-01-01

    Force tests of a series of right circular cones having semivertex angles ranging from 5 deg to 45 deg and a series of right circular cone-cylinder configurations having semivertex angles ranging from 5 deg to 20 deg and an afterbody fineness ratio of 6 have been made in the Langley 11-inch hypersonic tunnel at a Mach number of 6.83, a Reynolds number of 0.24 x 10.6 per inch, and angles of attack up to 130 deg. An analysis of the results made use of the Newtonian and modified Newtonian theories and the exact theory. A comparison of the experimental data of both cone and cone-cylinder configurations with theoretical calculations shows that the Newtonian concept gives excellent predictions of trends of the force characteristics and the locations with respect to angle of attack of the points of maximum lift, maximum drag, and maximum lift-drag ratio. Both the Newtonian a.nd exact theories give excellent predictions of the sign and value of the initial lift-curve slope. The maximum lift coefficient for conical bodies is nearly constant at a value of 0.5 based on planform area for semivertex angles up to 30 deg. The maximum lift-drag ratio for conical bodies can be expected to be not greater than about 3.5, and this value might be expected only for slender cones having semivertex angles of less than 5 deg. The increments of angle of attack and lift coefficient between the maximum lift-drag ratio and the maximum lift coefficient for conical bodies decrease rapidly with increasing semivertex angles as predicted by the modified Newtonian theory.

  14. Artificial gravity with ergometric exercise preserves the cardiac, but not cerebrovascular, functions during 4 days of head-down bed rest.

    PubMed

    Yang, Chang-Bin; Wang, Yong-Chun; Gao, Yuan; Geng, Jie; Wu, Yan-Hong; Zhang, Yu; Shi, Fei; Sun, Xi-Qing

    2011-12-01

    Cardiovascular and musculoskeletal deconditioning occurring in long-term spaceflight requires new strategies to counteract these adverse effects. We previously reported that a short-arm centrifuge produced artificial gravity (AG), together with ergometer, has an approving effect on promoting cardiovascular function. The current study sought to investigate whether the cardiac and cerebrovascular functions were maintained and improved using a strategy of AG combined with exercise training on cardiovascular function during 4-day head-down bed rest (HDBR). Twelve healthy male subjects were assigned to a control group (CONT, n=6) and an AG combined with ergometric exercise training group (CM, n=6). Simultaneously, cardiac pumping and systolic functions, cerebral blood flow were measured before, during, and after HDBR. The results showed that AG combined with ergometric exercise caused an increase trend of number of tolerance, however, there was no significant difference between the two groups. After 4-day HDBR in the CONT group, heart rate increased significantly (59±6 vs 66±7 beats/min), while stroke volume (98±12 vs 68±13 mL) and cardiac output (6±1 vs 4±1 L/min) decreased significantly (p<0.05). All subjects had similar drops on cerebral vascular function. Volume regulating hormone aldosterone increased in both groups (by 119.9% in CONT group and 112.8% in the CM group), but only in the CONT group there were a significant changes (p<0.05). Angiotensin II was significantly increased by 140.5% after 4-day HDBR in the CONT group (p<0.05), while no significant changes were observed in the CM group. These results indicated that artificial gravity with ergometric exercise successfully eliminated changes induced by simulated weightlessness in heart rate, volume regulating hormones, and cardiac pumping function and partially maintained cardiac systolic function. Hence, a daily 1h alternating +1.0 and +2.0 Gz with 40 W exercise training appear to be an effective

  15. Plasma volume and water/sodium balance differences due to sex and menstrual phase after 4 hours of head-down bed rest (HDBR).

    NASA Astrophysics Data System (ADS)

    Edgell, Heather; Grinberg, Anna; Beavers, Keith; Gagne, Nathalie; Totosy de Zepetnek, Julia; Greaves, Danielle; Hughson, Richard L.

    In both sexes, orthostatic responses are impaired by spaceflight or head-down bed-rest (HDBR), with a greater impact in women. Decreased plasma volume (PV) could contribute to reductions in cardiac output and blood pressure upon an orthostatic challenge. We hypothesized that a greater decrease in PV in women might lead to poorer orthostatic responses. We further hypothesized that the responses in women would differ throughout the menstrual cycle. We studied the responses of men (n=6) and women (n= 6) to 4-hr HDBR and 4-hr seated control (SEAT). Furthermore, we studied women in both the follicular (Day 8-11) and luteal (Day 18-24) phases of menstruation in a repeated measures design. After 4-hr HDBR, PV decreased in men (-175.1 ± 56.8 mL; vs. SEAT: P=0.076) and in the follicular phase, but did not change in the luteal phase (Luteal: -55.0 ± 54.6 mL; Follicular: -226.4 ± 88.2 mL (Interaction effect: P=0.01)). After 4-hr HDBR, only men appear to exhibit increased urine volume (Men, difference from SEAT: +298.3 ± 105.5 mL; Luteal, difference from SEAT: +59.4 ± 34.3 mL; Follicular, difference from SEAT: +43.7 ± 190.0 mL; P=0.16). No changes in urinary sodium after 4-hr HDBR were observed in any group (Men, difference from SEAT: -16.5 ± 13.5 µmol; Luteal, difference from SEAT: -8.0 ± 8.8 µmol; Follicular, difference from SEAT: +28.2 ± 29.5 µmol; P=0.264). No changes in urinary osmolarity were observed after 4-hr HDBR in any group (Men, difference from SEAT: -38.8 ± 126.2 mmol/kg; Luteal, difference from SEAT: -85.1 ± 66.9 mmol/kg; Follicular, difference from SEAT: -99.1 ± 98.5 mmol/kg; P=0.906). The changes in plasma volume do not appear to be a result of urinary water and sodium loss. Perhaps actions of atrial natriuretic peptide, urodilatin, the RAAS pathway, and/or capillary filtration are involved. From these observed changes in plasma volume, we surmise that women in the follicular phase of the menstrual cycle may exhibit lower cardiac output and thus

  16. Effect of Head-Down Bed Rest and Artificial Gravity Countermeasure on Cardiac Autonomic and Advanced Electrocardiographic Function

    NASA Technical Reports Server (NTRS)

    Schlegel, T. T.; Platts, S.; Stenger, M.; Ribeiro, C.; Natapoff, A.; Howarth, M.; Evans, J.

    2007-01-01

    To study the effects of 21 days of head-down bed rest (HDBR), with versus without an artificial gravity (AG) countermeasure, on cardiac autonomic and advanced electrocardiographic function. Fourteen healthy men participated in the study: seven experienced 21 days of HDBR alone ("HDBR controls") and seven the same degree and duration of HDBR but with approximately 1hr daily short-arm centrifugation as an AG countermeasure ("AG-treated"). Five minute supine high-fidelity 12-lead ECGs were obtained in all subjects: 1) 4 days before HDBR; 2) on the last day of HDBR; and 3) 7 days after HDBR. Besides conventional 12-lead ECG intervals and voltages, all of the following advanced ECG parameters were studied: 1) both stochastic (time and frequency domain) and deterministic heart rate variability (HRV); 2) beat-to-beat QT interval variability (QTV); 3) T-wave morphology, including signal-averaged T-wave residua (TWR) and principal component analysis ratios; 4) other SAECG-related parameters including high frequency QRS ECG and late potentials; and 5) several advanced ECG estimates of left ventricular (LV) mass. The most important results by repeated measures ANOVA were that: 1) Heart rates, Bazett-corrected QTc intervals, TWR, LF/HF power and the alpha 1 of HRV were significantly increased in both groups (i.e., by HDBR), but with no relevant HDBR*group differences; 2) All purely "vagally-mediated" parameters of HRV (e.g., RMSSD, HF power, Poincare SD1, etc.), PR intervals, and also several parameters of LV mass (Cornell and Sokolow-Lyon voltages, spatial ventricular activation times, ventricular gradients) were all significantly decreased in both groups (i.e., by HDBR), but again with no relevant HDBR*group differences); 3) All "generalized" or "vagal plus sympathetic" parameters of stochastic HRV (i.e., SDNN, total power, LF power) were significantly more decreased in the AG-treated group than in the HDBR-only group (i.e., here there was a relevant HDBR*group difference

  17. The effect of intermittent standing or walking during head down tilt bedrest on peak O2 consumption

    NASA Technical Reports Server (NTRS)

    Ertl, A. C.; Dearborn, A. S.; Vernikos, J.

    1992-01-01

    The cardiovascular aspect of bedrest deconditioning is manifested by decreases in peak O2 uptake (VO(sub 2 peak)) during minimal exercise. The effect of intermittent standing (+G(z)) or walking (+G(z)W) during 4 days of 7 degree Head Down Tilt bedrest (HDT) on VO(sub 2 peak) was evaluated. Methods: Five protocols were performed by eight male subjects; control (C) consisting of complete bedrest, and 15 minute periods to total 2 or 4 hours daily of standing (+G(z)(exp 2) and +G(z)(exp 4) respectively) or walking at 3.0 MPH (+G(z)W2 and +G(z)W4 respectively). Subjects performed VO(sub 2 peak) tests prior to and on the final day of HDT. VO(sub 2 peak) was determined using open circuit indirect calorimetry during supine leg cycling ergometry. After a 5 minute warmup, three 2 minute incremental loads of 33 W previously determined to elicit VO(sub 2 peak) were given and the subject cycled to volitional fatigue. Results: The C protocol VO(sub 2 peak) decreased by 16 percent (2.71 plus or minus 0.16 to 2.27 plus or minus 0.14 L/min) and 11 percent in +G(z)(exp 4) (2.72 plus or minus 0.15 to 2.43 plus or minus 0.14 L/min). With +G(z)W2 VO(sub 2 peak) decreased by 9 percent (2.71 plus or minus 0.17 to 2.46 plus or minus 0.14 L/min) and with +G(z)W4, VO(sub 2 peak) decreased by 10 percent (2.71 plus or minus 0.14 to 2.43 plus or minus 0.14 L/min). VO(sub 2 peak) in all protocols decreased with HDT (P less than 0.05). The decrease in C VO(sub 2 peak) was significantly greater (P less than 0.05) than the decreases in either +G(z) or +G(z)W protocols. Conclusion: The deconditioning that occurs after only 4 days of HDT was demonstrated by decreases in VO(sub 2 peak). Intermittent +G(z) or +G(z)W attenuated, but did not prevent, the decrease in VO(sub 2 peak) with HDT.

  18. Assessment of Lumbar Intervertebral Disc Glycosaminoglycan Content by Gadolinium-Enhanced MRI before and after 21-Days of Head-Down-Tilt Bedrest

    PubMed Central

    Koy, Timmo; Zange, Jochen; Rittweger, Jörn; Pohle-Fröhlich, Regina; Hackenbroch, Matthias; Eysel, Peer; Ganse, Bergita

    2014-01-01

    During spaceflight, it has been shown that intervertebral discs (IVDs) increase in height, causing elongation of the spine up to several centimeters. Astronauts frequently report dull lower back pain that is most likely of discogenic origin and may result from IVD expansion. It is unknown whether disc volume solely increases by water influx, or if the content of glycosaminoglycans also changes in microgravity. Aim of this pilot study was to investigate effects of the spaceflight analog of bedrest on the glycosaminoglycan content of human lumbar IVDs. Five healthy, non-smoking, male human subjects of European descent were immobilized in 6° head-down-tilt bedrest for 21 days. Subjects remained in bed 24 h a day with at least one shoulder on the mattress. Magnetic Resonance Imaging (MRI) scans were taken according to the delayed gadolinium-enhanced magnetic resonance imaging (dGEMRIC) protocol before and after bedrest. The outcome measures were T1 and ΔT1. Scans were performed before and after administration of the contrast agent Gd-DOTA, and differences between T1-values of both scans (ΔT1) were computed. ΔT1 is the longitudinal relaxation time in the tissue and inversely related to the glycosaminoglycan-content. For data analysis, IVDs L1/2 to L4/5 were semi-automatically segmented. Zones were defined and analyzed separately. Results show a highly significant decrease in ΔT1 (p<0.001) after bedrest in all IVDs, and in all areas of the IVDs. The ΔT1-decrease was most prominent in the nucleus pulposus and in L4/5, and was expressed slightly more in the posterior than anterior IVD. Unexpected negative ΔT1-values were found in Pfirrmann-grade 2-discs after bedrest. Significantly lower T1 before contrast agent application was found after bedrest compared to before bedrest. According to the dGEMRIC-literature, the decrease in ΔT1 may be interpreted as an increase in glycosaminoglycans in healthy IVDs during bedrest. This interpretation seems contradictory to

  19. Laboratory discharge studies of a 6 V alkaline lantern-type battery Eveready Energizer no. 528, under various ambient temperatures (-15 deg C and + 22 deg C) and loads (30 omega and 60 omega)

    NASA Technical Reports Server (NTRS)

    Ahrens, S. T.

    1984-01-01

    The voltages of two Eveready No. 528 batteries, one the test battery, the other the control battery, were simultaneously recorded as they were discharged across 30 omega loads using a dual chart recorder. The test battery was initially put in a freezer at -15 + or - 3 C. After its voltage had fallen to .6 V, it was brought back out into the room at 22 + or - 3 C. A second run was made with 60 omega loads. Assuming a 3.0 V cut-off, the total energy output of the test battery at -15 C was 26 WHr 30 omega and 35 WHr 60 omega, and the corresponding numbers for the control battery at 22 C were 91 WHr and 100 WHr. When the test battery was subsequently allowed to warm up, the voltage rose above 4 V and the total energy output rose to 80 WHr 30 omega and 82 WHR 60 omega.

  20. Effect of 1% Inspired CO2 During Head-Down Tilt on Ocular Structures, Cerebral Blood Flow, and Visual Acuity in Healthy Human Subjects

    NASA Technical Reports Server (NTRS)

    Laurie, S. S.; Hu, X.; Lee, S. M. C.; Martin, D. S.; Phillips, T. R.; Ploutz-Snyder, R.; Smith, S. M.; Stenger, M. B.; Taibbi, G.; Zwart, S. R.; Vizzeri, G.

    2016-01-01

    The cephalad fluid shift induced by microgravity has been hypothesized to elevate intracranial pressure (ICP) and contribute to the development of the visual impairment/intracranial pressure (VIIP) syndrome experienced by many astronauts during and after long-duration space flight. In addition, elevated ambient partial pressure of carbon dioxide (PCO2) on the International Space Station (ISS) has also been hypothesized to contribute to the development of VIIP. We seek to determine if an acute, mild CO2 exposure, similar to that occurring on the ISS, combined with the cephalad fluid shift induced by head-down tilt will induce ophthalmic and ICP changes consistent with the VIIP syndrome.

  1. Focal Gray Matter Plasticity as a Function of Long Duration Head Down Tilted Bed Rest: Preliminary Results

    NASA Technical Reports Server (NTRS)

    Koppelmans, V.; Erdeniz, B.; DeDios, Y. E.; Wood, S. J.; Reuter-Lorenz, P. A.; Kofman, I.; Bloomberg, J. J.; Mulavara, A. P.; Seidler, R. D.

    2014-01-01

    Long duration spaceflight (i.e., 22 days or longer) has been associated with changes in sensorimotor systems, resulting in difficulties that astronauts experience with posture control, locomotion, and manual control. The microgravity environment is an important causal factor for spaceflight induced sensorimotor changes. Whether these sensorimotor changes are solely related to peripheral changes from reduced vestibular stimulation, body unloading, body fluid shifts or that they may be related to structural and functional brain changes is yet unknown. However, a recent study reported associations between microgravity and flattening of the posterior eye globe and protrusion of the optic nerve [1] possibly as the result of increased intracranial pressure due to microgravity induced bodily fluid shifts [3]. Moreover, elevated intracranial pressure has been related to white matter microstructural damage [2]. Thus, it is possible that spaceflight may affect brain structure and thereby cognitive functioning. Long duration head down tilt bed rest has been suggested as an exclusionary analog to study microgravity effects on the sensorimotor system [4]. Bed rest mimics microgravity in body unloading and bodily fluid shifts. In consideration of the health and performance of crewmembers both in- and post-flight, we are conducting a prospective longitudinal 70-day bed rest study as an analog to investigate the effects of microgravity on brain structure [5]. Here we present results of the first six subjects. Six subjects were assessed at 12 and 7 days before-, at 7, 30, and 70 days in-, and at 8 and 12 days post 70 days of bed rest at the NASA bed rest facility in UTMB, Galveston, TX, USA. At each time point structural MRI scans (i.e., high resolution T1-weighted imaging and Diffusion Tensor Imaging (DTI)) were obtained using a 3T Siemens scanner. Focal changes over time in gray matter density were assessed using the voxel based morphometry 8 (VBM8) toolbox under SPM

  2. Low-magnitude whole body vibration with resistive exercise as a countermeasure against cardiovascular deconditioning after 60 days of head-down bed rest.

    PubMed

    Coupé, Mickael; Yuan, Ming; Demiot, Claire; Bai, Yanqiang Q; Jiang, Shizhong Z; Li, Yongzhi Z; Arbeille, Philippe; Gauquelin-Koch, Guillemette; Levrard, Thibaud; Custaud, Marc-Antoine; Li, Yinghui H

    2011-12-01

    Whole body vibration with resistive exercise is a promising countermeasure against some weightlessness-induced dysfunctions. Our objective was to study whether the combination of low-magnitude whole body vibration with a resistive exercise can prevent the cardiovascular deconditioning induced by a nonstrict 60-day head-down bed rest (Earth Star International Bed Rest Experiment Project). Fourteen healthy men participated in this study. We recorded electrocardiograms and blood pressure waves by means of a noninvasive beat-by-beat measurement system (Cardiospace, integrated by Centre National d'Etudes Spatiales and Astronaut Center of China) during an orthostatic test (20 min of 75-degree head-up tilt test) before and immediately after bed rest. We estimated heart rate, blood pressure, cardiac output, stroke volume, total peripheral resistance, baroreflex sensitivity, and heart rate variability. Low-magnitude whole body vibration with resistive exercise prevented an increase of the sympathetic index (reflecting the sympathovagal balance of cardiac autonomic control) and limited the decrease of the spontaneous baroreflex sensitivity induced by 60 days of head-down bed rest. However, this countermeasure had very little effect on cardiac hemodynamics and did not improve the orthostatic tolerance. This combined countermeasure did not efficiently prevent orthostatic intolerance but prevents changes in the autonomic nervous system associated with cardiovascular deconditioning. The underlying mechanisms remain hypothetical but might involve cutaneous and muscular mechanoreceptors. PMID:21900640

  3. Crystallographic Study of Mixtures La1+xBa2-xCu3Oy (x=0,0.2,0.4,0.6) after annealing at 860 deg. C

    SciTech Connect

    Stergiou, A.; Yilmaz, S.; Stergiou, C.

    2007-04-23

    Four powder mixtures with chemical formula La1+xBa2-xCu3Oy was prepared. The mixtures were heated in free atmosphere, at temperature 850 deg. C for 60h and then at 860 deg. C for 40h. XRD measurements were obtained with CuKa radiation. The samples were characterized with the help of the PDF and refined, using the Rietveld's 'Powder Profile Analysis'. Four phases, same for all the samples, were found: (La,Ba)2CuO4, BaCuO2, LaBa2Cu3O7-d, and BaCO3. The percentages of the tour phases are changed, as the x quantity increases, and varied from 38, 25, 18, 19%, for x=0, to 69, 14, 7, 10%, for x=0.6, respectively.

  4. Effects of 5 days of head-down bed rest, with and without short-arm centrifugation as countermeasure, on cardiac function in males (BR-AG1 study).

    PubMed

    Caiani, E G; Massabuau, P; Weinert, L; Vaïda, P; Lang, R M

    2014-09-15

    This study examined cardiac remodeling and functional changes induced by 5 days of head-down (-6°) bed rest (HDBR) and the effectiveness of short-arm centrifugation (SAC) in preventing them in males. Twelve healthy men (mean age: 33 ± 7) were enrolled in a crossover design study (BR-AG1, European Space Agency), including one sedentary (CTRL) and two daily SAC countermeasures (SAC1, 30 min continuously; SAC2, 30 min intermittently) groups. Measurements included plasma and blood volume and left ventricular (LV) and atrial (LA) dimensions by transthoracic echocardiography (2- and 3-dimensional) and Doppler inflows. Results showed that 5 days of HDBR had a major impact on both the geometry and cardiac function in males. LV mass and volume decreased by 16 and 14%, respectively; LA volume was reduced by 36%; Doppler flow and tissue Doppler velocities were reduced during early filling by 18 and 12%, respectively; and aortic flow velocity time integral was decreased by 18% with a 3% shortening of LV ejection time. These modifications were presumably due to decreased physiological loading and dehydration, resulting in reduced plasma and blood volume. All these changes were fully reversed 3 days after termination of HDBR. Moreover, SAC was not able to counteract these changes, either when applied continuously or intermittently. PMID:25080927

  5. WISE 2005-2006: 60-days of Head-Down Bed Rest Increases the Incidence of Menstrual Cycle Disruption

    NASA Astrophysics Data System (ADS)

    Wade, Charles

    post bed rest (day 0-day 60;EPBR) and late post bed rest (day 60-day 367;LPBR). Plasma PRG was significantly higher (p¡0.02) in the N group before BR and continued throughout the BR period. A significant difference in E2 was observed in the N group between PB and BR, BR and EPBR, and EPBR and LPBR (p¡0.01). E2 was significantly different between N and O during BR (p¡0.02). No differences were observed in the other plasma measurements. Daily urine samples demonstrated no changes in C or Aldo over the course of the study. At 6 and 12 months following completion of the study all subjects reported normal MC. Conclusion: The lengthening of menstrual cycle during bed rest is a result of a delay in ovulation due to the absence of a LH surge (ovulation) associated with lower PRG and E2 levels. In females, changes in menstrual cycles may be a contributing factor to the adverse responses to bed rest such as loss of bone mass, reductions in blood volume and decreased work performance.

  6. Isothermal Damage and Fatigue Behavior of SCS-6/Timetal 21S [0/90](Sub S) Composite at 650 Deg C

    NASA Technical Reports Server (NTRS)

    Castelli, Michael G.

    1994-01-01

    The isothermal fatigue damage and life behaviors of SCS-6/Timetal 21S (0/90)s were investigated at 650 C. Strain ratcheting and degradation of the composite's static elastic modulus were carefully monitored as functions of cycles to indicate damage progression. Extensive fractographic and metallographic analyses were conducted to determine damage/failure mechanisms. Resulting fatigue lives show considerable reductions in comparison to (0) reinforced titanium matrix composites subjected to comparable conditions. Notable stiffness degradations were found to occur after the first cycle of loading, even at relatively low maximum stress levels, where cyclic lives are greater than 25,000 cycles. This was attributed to the extremely weak fiber/matrix bond which fails under relatively low transverse loads. Stiffness degradations incurred on first cycle loadings and degradations thereafter were found to increase with increasing maximum stress. Environmental effects associated with oxidation of the (90) fiber interfaces clearly played a role in the damage mechanisms as fracture surfaces revealed environment assisted matrix cracking along the (90) fibers. Metallographic analysis indicated that all observable matrix fatigue cracks initiated at the (90) fiber/matrix interfaces. Global de-bonding in the loading direction was found along the (90) fibers. No surface initiated cracks were evident and minimal if any (0) fiber cracking was visible.

  7. Functional evidence of paraventricular nucleus involvement in cardiovascular and autonomic modulation in response to acute microgravity (head-down tilt) in unanesthetized rats.

    PubMed

    Amorim, Eric Diego Turossi; Peras, Vivian Rossi; de Andrade, Ozahyr; Martins-Pinge, Marli Cardoso

    2015-08-01

    Exposure to microgravity induces autonomic and vestibular disorders such as alterations in cardiovascular function. The paraventricular nucleus of the hypothalamus (PVN) is known to be an important center for integrating autonomic and cardiovascular responses as blood volume reflexes. The acute effects promoted by microgravity and PVN involvement in cardiovascular and autonomic parameters have not yet been evaluated. Male Wistar rats were anesthetized to facilitate cannulae implantation in the PVN. After 3 days of surgical recovery, femoral artery and vein catheters were implanted for direct recording of blood pressure and heart rate (HR) in conscious animals to evaluate cardiovascular and autonomic changes in an acute protocol of head-down tilt (HDT) in nonanesthetized rats. During HDT, there was an increase in mean arterial pressure (11 ± 1 mmHg, P < 0.05) and a decrease in HR (-28 ± 5 bpm, P < 0.05). Spectral analysis of systolic arterial pressure showed an increase in the low-frequency (LF) component. In addition, HDT induced a reduction in the LF component and an increase in the high-frequency (HF) component of the pulse interval (PI). PVN inhibition with muscimol reversed bradycardia and blocked the reduction of the LF and HF increases in PI during HDT. These results suggest that the PVN participates in the cardiovascular compensation during HDT, especially modulating cardiac responses. PMID:25821104

  8. 180 deg. domain structure and its evolution in Ca{sub 0.28}Ba{sub 0.72}Nb{sub 2}O{sub 6} ferroelectric single crystals of tungsten bronzes structure

    SciTech Connect

    Lu, C.J.; Nie, C.J.; Duan, X.F.; Li, J.Q.; Zhang, H.J.; Wang, J.Y.

    2006-05-15

    Ferroelectric domain structure and its evolution in uniaxial relaxor Ca{sub 0.28}Ba{sub 0.72}Nb{sub 2}O{sub 6} single crystals were investigated using transmission electron microscopy. It was found that there exists a high density of 180 deg. domain walls in the crystals. The domains appear predominantly spike shaped along the polar axis and have a typical diameter of 50-500 nm. Domain wall motion was occasionally induced by electron beam irradiation. Macrodomains-to-microdomains switching has been observed corresponding to the normal-to-relaxor ferroelectrics transition during an in situ heating experiments. At temperature just below ferroelectric phase transition temperature T{sub C}, zero-field-cooled needlelike nanodomains were also observed.

  9. Results of a 4-week head-down tilt with and without LBNP countermeasure: II. Cardiac and peripheral hemodynamics--comparison with a 25-day spaceflight.

    PubMed

    Arbeille, P; Gauquelin, G; Pottier, J M; Pourcelot, L; Güell, A; Gharib, C

    1992-01-01

    Cardiovascular hemodynamics were assessed by ultrasound echography and Doppler during a 28-d head-down tilt "CNES HDT: 87-88," and during the 25-d French-Soviet spaceflight "Aragatz 88." For both studies we used the same ultrasound methodology. The main hemodynamic parameters of the left heart function and of the peripheral arterial system (cerebral, renal, femoral arteries) were measured four times during the HDT (day 7, 14, 21, 28) and twice post-HDT. The same measurements were performed six times during the flight (day 4, 5, 15, 18, 20, 24) and five times postflight. During the HDT, two groups were studied: six subjects no countermeasures and six subjects with repeated lower body negative pressure (LBNP). In the first group the cardiac volumes and the cardiac output were significantly decreased, whereas in the group with LBNP these parameters were superior to the basal value. In the group without LBNP the cerebral flow was maintained because of a decrease of the brain vascular resistance. In this group the renal vascular resistance was decreased as inflight. In the lower limbs we observed a loss of the vasomotor control. The vascular resistance was decreased after the end of the HDT and the subjects suffered orthostatic intolerance. In the population with LBNP, we did not observe the same decrease of vascular resistance during the HDT, and after the HDT no sign of orthostatic intolerance was observed. During the flight, the left ventricular volume was significantly decreased. The carotid flow was maintained owing to a decrease of the cerebral vascular resistance.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1550542

  10. Cardiovascular responses to lower body negative pressure before and after 4 h of head-down bed rest and seated control in men and women.

    PubMed

    Edgell, H; Grinberg, A; Gagné, N; Beavers, K R; Hughson, R L

    2012-11-01

    Cardiovascular deconditioning after a 4-h head-down bed rest (HDBR) might be a consequence of the time of day relative to pre-HDBR testing, or simply 4 h of confinement and inactivity rather than the posture change. Ten men and 11 women were studied during lower body negative pressure (LBNP) before and after 4-h HDBR and 4-h seated posture (SEAT) as a control for time of day and physical inactivity effects to test the hypotheses that cardiovascular deconditioning was a consequence of the HDBR posture, and that women would have a greater deconditioning response. Following HDBR, men and women had lower blood volume, higher heart rate with a greater increase during LBNP, a greater decrease of stroke volume during LBNP, lower central venous pressure, smaller inferior vena cava diameter, higher portal vein resistance index with a greater increase during LBNP, but lower forearm vascular resistance, lower norepinephrine, and lower renin. Women had lower vasopressin and men had higher vasopressin after HDBR, and women had lower pelvic impedance and men higher pelvic impedance. Following SEAT, brachial vascular resistance was reduced, thoracic impedance was elevated, the reduction of central venous pressure during LBNP was changed, women had higher angiotensin II whereas men had lower levels, and pelvic impedance increased in women and decreased in men. Cardiovascular deconditioning was greater after 4-h HDBR than after SEAT. Women and men had similar responses for most cardiovascular variables in the present study that tested the responses to LBNP after short-duration HDBR compared with a control condition. PMID:22984250

  11. Decreasing ventromedial prefrontal cortex deactivation in risky decision making after simulated microgravity: effects of −6° head-down tilt bed rest

    PubMed Central

    Rao, Li-Lin; Zhou, Yuan; Liang, Zhu-Yuan; Rao, Henyi; Zheng, Rui; Sun, Yan; Tan, Cheng; Xiao, Yi; Tian, Zhi-Qiang; Chen, Xiao-Ping; Wang, Chun-Hui; Bai, Yan-Qiang; Chen, Shan-Guang; Li, Shu

    2014-01-01

    Space is characterized by risk and uncertainty. As humans play an important role in long-duration space missions, the ability to make risky decisions effectively is important for astronauts who spend extended time periods in space. The present study used the Balloon Analog Risk Task to conduct both behavioral and fMRI experiments to evaluate the effects of simulated microgravity on individuals' risk-taking behavior and the neural basis of the effect. The results showed that participants' risk-taking behavior was not affected by bed rest. However, we found that the ventromedial prefrontal cortex (VMPFC) showed less deactivation after bed rest and that the VMPFC activation in the active choice condition showed no significant difference between the win outcome and the loss outcome after bed rest, although its activation was significantly greater in the win outcome than in the loss outcome before bed rest. These results suggested that the participants showed a decreased level of value calculation after the bed rest. Our findings can contribute to a better understanding of the effect of microgravity on individual higher-level cognitive functioning. PMID:24904338

  12. Trends of OCS, HCN, SF6, CHClF2 (HCFC-22) in the Lower Stratosphere from 1985 and 1994 Atmospheric Trace Molecule Spectroscopy Experiment Measurements Near 30 deg. North Latitude

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Mahieu, E.; Zander, R.; Gunson, M. R.; Salawitch, R. J.; Chang, A. Y.; Goldman, A.; Abrams, M. C.; Abbas, M. M.; Newchurch, M. J.; Irion, F. W.

    1996-01-01

    Volume mixing ratio (VMR) profiles of OCS, HCN, SF6, and CHClF2 (HCFC-22) have been measured near 30 deg N latitude by the Atmospheric Trace Molecule Spectroscopy Fourier transform spectrometer during shuttle flights on 29 April - 6 May 1985 and 3-2 November 1994. The change in the concentration of each molecule in the lower stratosphere has been derived for this 9 1/2-year period by comparing measurements between potential temperatures of 395 to 800 K (approximately 17 to 30 km altitude) relative to simultaneously measured values of the long-lived tracer N2O. Exponential rates of increase inferred for 1985-to 1994 from these comparisons are (0.1 plus or minus 0.4)% yr(exp-1) for OCS, (1.0 plus or minus 1.0)% yr(exp-1) for HCN, (8.0 +/- 0.7)% yr(exp-1) for SF6, and (8.0 +/- 1.0)% yr(exp-1) for CHClF2 (HCFC-22), 1 sigma. The lack of an appreciable trend for OCS suggests the background (i.e. nonvolcanic) source of stratospheric aerosol was the same during the two periods. These results are compared with trends reported in the literature.

  13. SSF1deg-Day Aqua Ed4

    Atmospheric Science Data Center

    2016-06-08

    ... and Order:  Reverb   Reverb Tutorial Subset/Visualization Tool:  CERES Order Tool Search and Order:  ASDC Order ... Documents:  Detailed CERES SSF1deg-lite Product Information Data Products Catalog: DPC_SSF1deg-Day_Ed4_R6V1 ...

  14. Mutational analysis of the Bacillus subtilis DegU regulator and its phosphorylation by the DegS protein kinase.

    PubMed Central

    Dahl, M K; Msadek, T; Kunst, F; Rapoport, G

    1991-01-01

    The DegS-DegU protein kinase-response regulator pair controls the expression of genes encoding degradative enzymes as well as other cellular functions in Bacillus subtilis. Both proteins were purified. The DegS protein was autophosphorylated and shown to transfer its phosphate to the DegU protein. Phosphoryl transfer to the wild-type DegU protein present in crude extracts was shown by adding 32P-labeled DegS to the reaction mixture. Under similar conditions, the modified proteins encoded by the degU24 and degU31 alleles presented a stronger phosphorylation signal compared with that of the wild-type DegU protein. This may suggest an increased phosphorylation of these modified proteins, responsible for the hyperproduction of degradative enzymes observed in the degU24 and degU31 mutants. However, the degU32 allele, which also leads to hyperproduction of degradative enzymes, encodes a modified DegU response regulator which seems not to be phosphorylatable. The expression of the hyperproduction phenotype of the degU32 mutant is still dependent on the presence of a functional DegS protein. DegS may therefore induce a conformational change of the degU32-encoded response regulator enabling this protein to stimulate degradative enzyme synthesis. Two alleles, degU122 and degU146, both leading to deficiency of degradative enzyme synthesis, seem to encode phosphorylatable and nonphosphorylatable DegU proteins, respectively. Images PMID:1901568

  15. The structures of Arabidopsis Deg5 and Deg8 reveal new insights into HtrA proteases

    SciTech Connect

    Sun, Wei; Gao, Feng; Fan, Haitian; Shan, Xiaoyue; Sun, Renhua; Liu, Lin; Gong, Weimin

    2013-05-01

    The crystal structures of Arabidopsis Deg5 and Deg8 have been determined to resolutions of 2.6 and 2.0 Å, respectively, revealing novel structural features of HtrA proteases. Plant Deg5 and Deg8 are two members of the HtrA proteases, a family of oligomeric serine endopeptidases that are involved in a variety of protein quality-control processes. These two HtrA proteases are located in the thylakoid lumen and participate in high-light stress responses by collaborating with other chloroplast proteins. Deg5 and Deg8 degrade photodamaged D1 protein of the photosystem II reaction centre, allowing its in situ replacement. Here, the crystal structures of Arabidopsis thaliana Deg5 (S266A) and Deg8 (S292A) are reported at 2.6 and 2.0 Å resolution, respectively. The Deg5 trimer contains two calcium ions in a central channel, suggesting a link between photodamage control and calcium ions in chloroplasts. Previous structures of HtrA proteases have indicated that their regulation usually requires C-terminal PDZ domain(s). Deg5 is unique in that it contains no PDZ domain and the trimeric structure of Deg5 (S266A) reveals a novel catalytic triad conformation. A similar triad conformation is observed in the hexameric structure of the single PDZ-domain-containing Deg8 (S292A). These findings suggest a novel activation mechanism for plant HtrA proteases and provide structural clues to their function in light-stress response.

  16. 15 degrees head-down tilt attenuates the postexercise reduction in cutaneous vascular conductance and sweating and decreases esophageal temperature recovery time.

    PubMed

    McInnis, Natalie H; Journeay, W Shane; Jay, Ollie; Leclair, Emily; Kenny, Glen P

    2006-09-01

    The following study examined the effect of 15 degrees head-down tilt (HDT) on postexercise heat loss and hemodynamic responses. We tested the hypothesis that recovery from dynamic exercise in the HDT position would attenuate the reduction in the heat loss responses of cutaneous vascular conductance (CVC) and sweating relative to upright seated (URS) recovery in association with an augmented hemodynamic response and an increased rate of core temperature decay. Seven male subjects performed the following three experimental protocols: 1) 60 min in the URS posture followed by 60 min in the 15 degrees HDT position; 2) 15 min of cycle ergometry at 75% of their predetermined V(O2 peak) followed by 60 min of recovery in the URS posture; or 3) 15 min of cycle ergometry at 75% of their predetermined V(O2 peak) followed by 60 min of recovery in the 15 degrees HDT position. Mean skin temperature, esophageal temperature (T(es)), skin blood flow, sweat rate, cardiac output (CO), stroke volume (SV), heart rate (HR), total peripheral resistance, and mean arterial pressure (MAP) were recorded at baseline, end exercise, 2, 5, 8, 12, 15, and 20 min, and every 5 min until end of recovery (60 min). Without preceding exercise, HDT decreased HR and increased SV (P < or = 0.05). During recovery after exercise, a significantly greater MAP, SV, CVC, and sweat rate and a significantly lower HR were found with HDT compared with URS posture (P < or = 0.05). Subsequently, a significantly lower T(es) was observed with HDT after 15 min of recovery onward (P < or = 0.05). At the end of 60 min of recovery, T(es) remained significantly elevated above baseline with URS (P < or = 0.05); however, T(es) returned to baseline with HDT. In conclusion, extended recovery from dynamic exercise in the 15 degrees HDT position attenuates the reduction in CVC and sweating, thereby significantly increasing the rate of T(es) decay compared with recovery in the URS posture. PMID:16741261

  17. Pressure distribution on a 1- by 3-meter semispan wing at sweep angles from 0 deg to 40 deg in subsonic flow

    NASA Technical Reports Server (NTRS)

    Yip, L. P.; Shubert, G. L.

    1976-01-01

    A 1- by 3-meter semispan wing of taper ratio 1.0 with NACA 0012 airfoil section contours was tested in the Langley V/STOL tunnel to measure the pressure distribution at five sweep angles, 0 deg, 10 deg, 20 deg, 30 deg, and 40 deg, through an angle-of-attack range from -6 deg to 20 deg. The pressure data are presented as plots of pressure coefficients at each static-pressure tap location on the wing. Flow visualization wing-tuft photographs are also presented for a wing of 40 deg sweep. A comparison between theory and experiment using two inviscid theories and a viscous theory shows good agreement for pressure distributions, normal forces, and pitching moments for the wing at 0 deg sweep.

  18. Giant Electroresistive Ferroelectric Diode on 2DEG

    PubMed Central

    Kim, Shin-Ik; Jin Gwon, Hyo; Kim, Dai-Hong; Keun Kim, Seong; Choi, Ji-Won; Yoon, Seok-Jin; Jung Chang, Hye; Kang, Chong-Yun; Kwon, Beomjin; Bark, Chung-Wung; Hong, Seong-Hyeon; Kim, Jin-Sang; Baek, Seung-Hyub

    2015-01-01

    Manipulation of electrons in a solid through transmitting, storing, and switching is the fundamental basis for the microelectronic devices. Recently, the electroresistance effect in the ferroelectric capacitors has provided a novel way to modulate the electron transport by polarization reversal. Here, we demonstrate a giant electroresistive ferroelectric diode integrating a ferroelectric capacitor into two-dimensional electron gas (2DEG) at oxide interface. As a model system, we fabricate an epitaxial Au/Pb(Zr0.2Ti0.8)O3/LaAlO3/SrTiO3 heterostructure, where 2DEG is formed at LaAlO3/SrTiO3 interface. This device functions as a two-terminal, non-volatile memory of 1 diode-1 resistor with a large I+/I− ratio (>108 at ±6 V) and Ion/Ioff ratio (>107). This is attributed to not only Schottky barrier modulation at metal/ferroelectric interface by polarization reversal but also the field-effect metal-insulator transition of 2DEG. Moreover, using this heterostructure, we can demonstrate a memristive behavior for an artificial synapse memory, where the resistance can be continuously tuned by partial polarization switching, and the electrons are only unidirectionally transmitted. Beyond non-volatile memory and logic devices, our results will provide new opportunities to emerging electronic devices such as multifunctional nanoelectronics and neuromorphic electronics. PMID:26014446

  19. Global map of lithosphere thermal thickness on a 1 deg x 1 deg grid - digitally available

    NASA Astrophysics Data System (ADS)

    Artemieva, Irina

    2014-05-01

    This presentation reports a 1 deg ×1 deg global thermal model for the continental lithosphere (TC1). The model is digitally available from the author's web-site: www.lithosphere.info. Geotherms for continental terranes of different ages (early Archean to present) are constrained by reliable data on borehole heat flow measurements (Artemieva and Mooney, 2001), checked with the original publications for data quality, and corrected for paleo-temperature effects where needed. These data are supplemented by cratonic geotherms based on xenolith data. Since heat flow measurements cover not more than half of the continents, the remaining areas (ca. 60% of the continents) are filled by the statistical numbers derived from the thermal model constrained by borehole data. Continental geotherms are statistically analyzed as a function of age and are used to estimate lithospheric temperatures in continental regions with no or low quality heat flow data. This analysis requires knowledge of lithosphere age globally. A compilation of tectono-thermal ages of lithospheric terranes on a 1 deg × 1 deg grid forms the basis for the statistical analysis. It shows that, statistically, lithospheric thermal thickness z (in km) depends on tectono-thermal age t (in Ma) as: z=0.04t+93.6. This relationship formed the basis for a global thermal model of the continental lithosphere (TC1). Statistical analysis of continental geotherms also reveals that this relationship holds for the Archean cratons in general, but not in detail. Particularly, thick (more than 250 km) lithosphere is restricted solely to young Archean terranes (3.0-2.6 Ga), while in old Archean cratons (3.6-3.0 Ga) lithospheric roots do not extend deeper than 200-220 km. The TC1 model is presented by a set of maps, which show significant thermal heterogeneity within continental upper mantle. The strongest lateral temperature variations (as large as 800 deg C) are typical of the shallow mantle (depth less than 100 km). A map of the

  20. Polarization photometer to measure bidirectional reflectance factor R(55 deg, 0 deg, 55 deg, 180 deg) of leaves

    NASA Technical Reports Server (NTRS)

    Vanderbilt, V. C.; Grant, L.

    1986-01-01

    A polarization photometer has been developed for rapidly determining the bidirectional, polarized, and diffuse light-scattering properties of individual leavs illuminated and measured 'in vivo' at an angle of 55 deg (approximately Brewster's angle) in six wavelength bands in the visible and near-IR wavelength regions. The optical performance and data quality of the system are evaluated to estimate the magnitude of the variation in the data attributable to the instrument system and to measurement procedures. The potential to discriminate between three species of oak is demonstrated using data acquired by the polarization photometer. The instrument is being used to increase understanding of the radiation transfer process in plant canopies and specifically to determine how agronomic information of the physical and chemical processes in leaves, plants, and plant canopies is expressed in these light-scattering properties.

  1. Upper ocean thermal and flow fields at 0 deg, 28 deg W (Atlantic) and 0 deg, 140 deg W (Pacific) during 1983-1985

    NASA Technical Reports Server (NTRS)

    Halpern, David; Weisberg, Robert H.

    1989-01-01

    Moored current and temperature measurements were recorded simultaneously for 2 years (August 1983 to July 1985) at six or seven depths between 10 and 250 m on the equator at 28 deg W in the Atlantic and at 140 deg W in the Pacific. The mean depth of the 20-C isotherm, which was representative of thermocline displacements, was identical at both sites. Substantially different annual cycles of the thermal and flow fields represent an enigma. The annual variation of the 20-C isotherm was much less at 140 deg W than at 28 deg W.

  2. Hydrographic section across the Kuroshio near 35 deg N, 143 deg E

    NASA Technical Reports Server (NTRS)

    Teague, W. J.; Shiller, A. M.; Hallock, Z. R.

    1994-01-01

    A closely spaced conductivity-temperature-depth/hydrographic section was conducted off the east coast of Japan in July 1992. The southeastward section crossed the Japan Trench and the Kuroshio in the vicinity of the Kashima 1 seamount. Vertical sections of temperature, salinity, density, oxygen, and nutrients are discussed in conjunction with the movement and interleaving of water masses. Complicated vertical and horizontal mixings of water masses are inferred from the temperature and salinity relationships. Mixing processes are patchy and not continuous beneath the front. Warm, salty water found beneath the Kurishio may result from upward mixing of water from intermediate depths. The main axis of the Kurishio, indicated by the 14 C isotherm at 200 m, is at 35.7 deg N, 142.6 deg E, about 20 km from the north wall surface thermal front. Geostrophic speeds exceed 170 cm/s at the surface; volume transport through the section is 81 x 10(exp 6) cu m/s.

  3. Individual Differences in the Temporal Profile of Cardiovascular Responses to Head Down Tilt and Orthostatic Stress with and Without Fluid Loading

    NASA Technical Reports Server (NTRS)

    Cowings, Patricia; Toscano, William; Kanis, Dionisios; Gebreyesus, Fiyore

    2013-01-01

    Susceptibility of healthy astronauts to orthostatic hypotension and presyncope is exacerbated upon return from spaceflight. Hypo-volemia is suspected to play an important role in cardiovascular deconditioning following exposure to spaceflight, which may lead to increased peripheral resistance, attenuated arterial baroreflex, and changes in cardiac function. The effect of altered gravity during space flight and planetary transition on human cardiovascular function is of critical importance to maintenance of astronaut health and safety. A promising countermeasure for post-flight orthostatic intolerance is fluid loading used to restore loss fluid volume by giving crew salt tablets and water prior to re-entry. Eight men and eight women will be tested during two, 6-hour exposures to 6o HDT: 1) fluid loading, 2) no fluid loading. Before and immediately after each HDT, subjects will perform a stand test to assess their orthostatic tolerance. Physiological measures (e.g., ECG, blood pressure, peripheral blood volume) will be continuously monitored while echocardiography measures are recorded at 30-minute intervals during HDT and stand tests. Preliminary results (N=4) clearly show individual differences in responses to this countermeasure and the time course of physiological changes induced by HDT.

  4. The 2 deg/90 deg laboratory scattering photometer. [particulate refractivity in hydrosols

    NASA Technical Reports Server (NTRS)

    Mccluney, W. R. (Inventor)

    1977-01-01

    A scattering photometer for measuring the light scattered by particles in a hydrosol at substantially 2 deg and 90 deg simultaneously is described. Light from a source is directed by a first optical system into a scattering cell containing the hydrosol under study. Light scattered at substantially 90 deg to the incident beam is focused onto a first photoelectric detector to generate an electrical signal indicative of the amount of scattered light at substantially 90 deg. Light scattered at substantially 2 deg to the incident beam is directed through an annular aperture symmetrically located about the axis of the illuminating beam which is linearly transmitted undeviated through the hydrosol and focused onto a second photoelectric detector to generate an electrical signal indicative of the amount of light scattered at substantially 2 deg.

  5. NCLB Heads Down Alice's Rabbit Hole

    ERIC Educational Resources Information Center

    Starnes, Bobby Ann

    2005-01-01

    This article describes one unconventional elementary school teacher's frustrations with colleagues doubting her competence, intelligence, and sense of purpose as a teacher. In her classroom, she never used textbooks or had a teacher's desk. There were no contests, gold stars, or redbird reading groups. There were no school-supply decorations,…

  6. Estimates of equatorial upwelling between 140 deg and 110 deg W during 1984

    NASA Technical Reports Server (NTRS)

    Halpern, David; Knox, Robert A.; Luther, Douglas S.; Philander, S. George H.

    1989-01-01

    The equation of continuity is used to estimate profiles of vertical velocity between 25 and 120 m from moored current measurements in arrays nested within the triangle with vertices located at 1 deg 30 arcmins S, 140 deg W and along the equator at 140 deg and 110 deg W during December 1983 through March 1984 and May-September 1984. All directions of the 4- to 5-month mean values were upward. The ensemble averaged mean vertical velocity was 0.000022 m/s. Upwelling speeds decreased eastward.

  7. Heat-transfer test results for a .0275-scale space shuttle external tank with a 10 deg/40 deg double cone-ogive nose in the NASA/AMES 3.5-foot hypersonic wind tunnel (FH14), volume 2

    NASA Technical Reports Server (NTRS)

    Carroll, H. R.

    1977-01-01

    A .0275 scale forebody model of the new baseline configuration of the space shuttle external tank vent cap configuration was tested to determine the flow field due to the double cone configuration. The tests were conducted in a 3.5 foot hypersonic wind tunnel at alpha = -5 deg, -4.59 deg, 0 deg, 5 deg, and 10 deg; beta = 0 deg, -3 deg, -5.51 deg, -6 deg, -9 deg, and +6 deg; nominal freestream Reynolds numbers per foot of 1.5 x 1 million, 3.0 x 1 million, and 5.0 x 1 million; and a nominal Mach number of 5. Separation and reattached flow from thermocouple data, shadowgraphs, and oil flows indicate that separation begins about 80% from the tip of the 10 deg cone, then reattaches on the vent cap and produces fully turbulent flow over most of the model forebody. The hardware disturbs the flow over a much larger area than present TPS application has assumed. A correction to the flow disturbance was experimentally suggested from the results of an additional test run.

  8. Damage Initiation and Ultimate Tensile Strength of Scaled [0 deg n/90 deg n/0 deg n]sub T Graphite-Epoxy Coupons

    NASA Technical Reports Server (NTRS)

    Jackson, Karen E.; Prosser, William H.

    1997-01-01

    Previous research on scaling effects in composite materials has demonstrated that the stress levels at first ply failure and ultimate failure of composite laminates are dependent on the size of the laminate. In particular, the thickness dimension has been shown to be the most influential parameter in strength scaling of composite coupons loaded in tension. Geometrically and constitutively scaled laminates exhibit decreasing strength with increasing specimen size, and the magnitude of the strength-size effect is a function of both material properties and laminate stacking sequence. Some of the commonly used failure criteria for composite materials such as maximum stress, maximum strain, and tensor polynomial (e.g., Tsai-Wu) cannot account for the strength-size effect. In this paper, three concepts are developed and evaluated for incorporating size dependency into failure criteria for composite materials. An experimental program of limited scope was performed to determine the first ply failure stress in scaled cross-ply laminates loaded in tension. Test specimens were fabricated of AS-4/3502 graphite-epoxy composite material with laminate stacking sequences of [0 deg n/90 deg n/o deg n]subT where n=1-6. Two experimental techniques were used to determine first ply failure, defined as a transverse matrix crack in the 90 deg ply: (1) step loading with dye penetrant x-ray of the specimen at each load interval, and (2) acoustic emission. The best correlation between first ply failure analysis and experimental data was obtained using a modified Weibull approach which incorporated the residual thermal stress and the outer ply constraint, as well as the ply thickness effect. Finally, a second set of experiments was performed to determine the tensile response and ultimate failure of the scaled cross-ply laminates. The results of these experiments indicated no influence of specimen size on tensile response or ultimate strength.

  9. Deg Xinag. Ingalik Noun Dictionary (Preliminary).

    ERIC Educational Resources Information Center

    Kari, James, Comp.

    This dictionary contains lists of nouns in the Deg Xinag or Ingalik language as spoken in the Yukon River villages of Anvik, Shageluk, and Holy Cross, and the Kuskokwim River village of Stony River. After a presentation of the Ingalik alphabet, the nouns, with English equivalents, are listed according to the following categories: mammals; fish;…

  10. The system Ce-Zn-B at 800 deg. C

    SciTech Connect

    Malik, Z.; Sologub, O.; Giester, G.; Rogl, P.

    2011-11-15

    The isothermal section for the system Ce-Zn-B has been established at 800 deg. C using electron microprobe analysis and X-ray powder diffraction. No ternary compounds exist and mutual solid solubilities of binary phases are negligible. In the concentration range of 10.0-10.5 at% Ce two structural modifications have been confirmed: high temperature {beta}Ce{sub 2}Zn{sub 17} above {approx}750 deg. C with the Th{sub 2}Zn{sub 17} type (R3-bar m, a=0.90916(4) nm, c=1.3286(1) nm) and low temperature {alpha}CeZn{sub 7} (Ce{sub 1-x}Zn{sub 5+2x}; x{approx}0.33) up to 750 deg. C for which we attributed the TbCu{sub 7} type (P6/mmm, a=0.52424(2), c=0.44274(1) nm). The crystal structure of CeZn{sub 7} was derived from the Rietveld refinement of X-ray powder intensities. Precise data on atom site distribution and positional parameters have been furthermore provided from X-ray single crystal refinements for two compounds, for which crystal structures hitherto have only been derived from X-ray diffraction photographs: Ce{sub 3}Zn{sub 11} (Immm, a=0.45242(2) nm, b=0.88942(3) nm, c=1.34754(4) nm) and Ce{sub 3}Zn{sub 22} (I4{sub 1}/amd; a=0.89363(2) nm, c=2.1804(5) nm). - Graphical abstract: Existence of low temperature modification {alpha}CeZn{sub 7} (Ce{sub 1-x}Zn{sub 5+2x}; x{approx}0.33) of Ce{sub 2}Zn{sub 17} has been verified up to 750 deg. C that is attributed with the TbCu{sub 7} type. Highlights: > Isothermal section of system Ce-Zn-B at 800 deg. C. > In System Ce-Zn, X-ray single crystal intensity data refinement of Ce{sub 3}Zn{sub 11} and Ce{sub 3}Zn{sub 22} and Rietveld refinement of Ce{sub 13}Zn{sub 58}. > Two temperature modifications of Ce{sub 2}Zn{sub 17}, rhombohedral {beta}Ce{sub 2}Zn{sub 17} (hT) and of hexagonal {alpha}CeZn{sub 7} (lT). > No ternary compound in the System Ce-Zn-B (<50 at% Ce) at 800 deg. C.

  11. A very deep IRAS survey at l(II) = 97 deg, b(II) = +30 deg

    NASA Technical Reports Server (NTRS)

    Hacking, Perry; Houck, James R.

    1987-01-01

    A deep far-infrared survey is presented using over 1000 scans made of a 4 to 6 sq. deg. field at the north ecliptic pole by the IRAS. Point sources from this survey are up to 100 times fainter than the IRAS point source catalog at 12 and 25 micrometers, and up to 10 times fainter at 60 and 100 micrometers. The 12 and 25 micrometer maps are instrumental noise-limited, and the 60 and 100 micrometer maps are confusion noise-limited. The majority of the 12 micrometer point sources are stars within the Milky Way. The 25 micrometer sources are composed almost equally of stars and galaxies. About 80% of the 60 micrometer sources correspond to galaxies on Palomar Observatory Sky Survey (POSS) enlargements. The remaining 20% are probably galaxies below the POSS detection limit. The differential source counts are presented and compared with what is predicted by the Bahcall and Soneira Standard Galaxy Model using the B-V-12 micrometer colors of stars without circumstellar dust shells given by Waters, Cote and Aumann. The 60 micrometer source counts are inconsistent with those predicted for a uniformly distributed, nonevolving universe. The implications are briefly discussed.

  12. Characterization of the interaction layer in diffusion couples U-7 wt.%Mo/Al 6061 alloy at 550 deg. C and 340 deg. C

    SciTech Connect

    Mirandou, M.I.; Arico, S.F.; Balart, S.N.; Gribaudo, L.M.

    2009-08-15

    Solid state reaction between U-7 wt.%Mo and Al 6061 alloys at 550 deg. C and 340 deg. C was characterized in chemical diffusion couples made by Friction Stir Welding. Results were obtained from optical and scanning electron microscopy, electron probe microanalysis and X-ray diffraction. At 550 deg. C the interaction layer in {gamma}U(Mo)/Al 6061 is formed by U(Al,Si){sub 3} phase but when {gamma}U(Mo) cellular decomposition occurs, UAl{sub 3} and Al{sub 43}Mo{sub 4}U{sub 6} also appear in the interaction layer. At 340 deg. C the use of X-ray diffraction with synchrotron radiation made it possible to analyze the interaction layer. It was found that it is only formed by U{sub 3}Si{sub 5} phase with its cell volume enlarged respect to the original one.

  13. Bacillus subtilis Two-Component System Sensory Kinase DegS Is Regulated by Serine Phosphorylation in Its Input Domain

    PubMed Central

    Jers, Carsten; Kobir, Ahasanul; Søndergaard, Elsebeth Oline; Jensen, Peter Ruhdal; Mijakovic, Ivan

    2011-01-01

    Bacillus subtilis two-component system DegS/U is well known for the complexity of its regulation. The cytosolic sensory kinase DegS does not receive a single predominant input signal like most two-component kinases, instead it integrates a wide array of metabolic inputs that modulate its activity. The phosphorylation state of the response regulator DegU also does not confer a straightforward “on/off” response; it is fine-tuned and at different levels triggers different sub-regulons. Here we describe serine phosphorylation of the DegS sensing domain, which stimulates its kinase activity. We demonstrate that DegS phosphorylation can be carried out by at least two B. subtilis Hanks-type kinases in vitro, and this stimulates the phosphate transfer towards DegU. The consequences of this process were studied in vivo, using phosphomimetic (Ser76Asp) and non-phosphorylatable (Ser76Ala) mutants of DegS. In a number of physiological assays focused on different processes regulated by DegU, DegS S76D phosphomimetic mutant behaved like a strain with intermediate levels of DegU phosphorylation, whereas DegS S76A behaved like a strain with lower levels of DegU phophorylation. These findings suggest a link between DegS phosphorylation at serine 76 and the level of DegU phosphorylation, establishing this post-translational modification as an additional trigger for this two-component system. PMID:21304896

  14. Crystallographic Study of Mixture CeBa1.8Pb0.2Cu3Oy in the Range of 860 deg. C to 940 deg. C

    SciTech Connect

    Stergiou, A.; Yilmaz, S.; Stergiou, C.

    2007-04-23

    A powder mixture with chemical formula CeBa1.8Pb0.2Cu3Oy was prepared. The mixture was heated in free atmosphere, at temperatures 860 deg. C to 940 deg. C, for 24 to 72h. The samples were measured by X-Ray powder diffraction with CuKa radiation. Each sample was characterized with the help of the PDF and refined, using the Rietveld's ''Powder Profile Analysis''. The first sample (860 deg. C) was identified with the phases: Ba2CeBiO6, CuO and BaCuO2, while all the remaining samples (870 deg. C-940 deg. C) with the phases Ba2CePbO6, CuO and CeO2. The phases Ba2CeBiO6 and Ba2CePbO6 are the main phases with analogous chemical types, but different symmetry. The phase CuO is common in all the samples, while from the remaining phases the BaCuO2 appears only in the first sample and the CeO2 in all, except the first one. The quantity 0.2 of Pb is distributed in the Ba positions, substituting a part of these. The percentages of phases are about 82%, 10% and 8% for the first sample and for all the remaining about 85%, 8% and 7%, respectively with above serious.

  15. Two stress sensor proteins for the expression of sigmaE regulon: DegS and RseB.

    PubMed

    Kim, Dong Young

    2015-05-01

    In E. coli, sigmaE-dependent transcription is controlled by regulated-proteolysis of RseA. RseA, which holds sigmaE as an anti-sigma factor, is sequentially digested by DegS, RseP and cytoplasmic proteases to liberate sigmaE in response to dysfunction in outer-membrane biogenesis. Additionally, the sequential proteolysis is regulated by RseB binding to RseA (Fig. 1A). Direct interaction between RseA and RseB inhibits RseA-cleavage by DegS. Both proteolytic activation of DegS and binding disruption of RseB are thus required to initiate sigmaE-stress response. For the induction of sigmaEstress response, DegS and RseB recognize the states of OMP and LPS for outer-membrane biogenesis. DegS is activated by binding of unfolded OMPs and RseB binding to RseA is antagonized by LPS accumulated in periplasm. In this regard, DegS and RseB are proposed to be stress sensor proteins for sigmaE signal transduction. Interestingly, biogenesis of OMP and LPS appears to cross-talk with each other, indicating that dysfunction of either OMP or LPS can initiate RseA proteolysis. This review aims to briefly introduce two stress sensor proteins, DegS and RseB, which regulate sigmaEdependent transcription. PMID:25935301

  16. Catalogue of the discrete sources in the declination range from -13 deg to -2 deg

    SciTech Connect

    Braude, S.Y.; Miroshnitchenko, A.P.; Sokolov, K.P.; Sharykin, N.K.

    1984-08-01

    The results of the discrete source measurements with declinations -13 deg or delta or -2 deg and right ascensions 0 sub h + 24 sub h are given and were obtained as part of the systematic decametric survey of the celestial sphere with the rotatiotelecope UTR-2. Three hundred sixteen sources were found in the given declination range, four of which were observed for the first time. The source coordinates measured in the survey were compared with those from the 4th Cambridge survey at 178 MHz and the Parkes survey at 408 MHz.

  17. Winds from the Atlanta /34 deg N, 84 deg W/ radio meteor wind facility

    NASA Technical Reports Server (NTRS)

    Roper, R. G.

    1978-01-01

    A brief description of the Georgia Tech radio meteor wind facility is followed by a tabular presentation and discussion of winds measured over Atlanta (34 deg N, 84 deg W) for the first three intervals of the URSI/IAGA Cooperative Tidal Observations Program (CTOP). The pervailing zonal wind measured during August 1974, being easterly, is significantly different from that measured during October 1975 and January 1976, and is not typical of winds measured in August 1975 and August 1976, when westerlies predominated. The complicated tidal picture is detailed, but is not easily summarized.

  18. The catalogue of the discrete sources in the declination range from -13 deg to -2 deg

    NASA Technical Reports Server (NTRS)

    Braude, S. Y.; Miroshnitchenko, A. P.; Sokolov, K. P.; Sharykin, N. K.

    1984-01-01

    The results of the discrete source measurements with declinations -13 deg or = delta or = -2 deg and right ascensions 0 sub h + 24 sub h are given and were obtained as part of the systematic decametric survey of the celestial sphere with the rotatiotelecope UTR-2. Three hundred sixteen sources were found in the given declination range, four of which were observed for the first time. The source coordinates measured in the survey were compared with those from the 4th Cambridge survey at 178 MHz and the Parkes survey at 408 MHz.

  19. Allostery Is an Intrinsic Property of the Protease Domain of DegS Implications for Enzyme Function and Evolution

    SciTech Connect

    Sohn, Jungsan; Grant, Robert A.; Sauer, Robert T.

    2010-12-02

    DegS is a periplasmic Escherichia coli protease, which functions as a trimer to catalyze the initial rate-limiting step in a proteolytic cascade that ultimately activates transcription of stress response genes in the cytoplasm. Each DegS subunit consists of a protease domain and a PDZ domain. During protein folding stress, DegS is allosterically activated by peptides exposed in misfolded outer membrane porins, which bind to the PDZ domain and stabilize the active protease. It is not known whether allostery is conferred by the PDZ domains or is an intrinsic feature of the trimeric protease domain. Here, we demonstrate that free DegS{sup {Delta}PDZ} equilibrates between active and inactive trimers with the latter species predominating. Substrate binding stabilizes active DegS{sup {Delta}PDZ} in a positively cooperative fashion. Mutations can also stabilize active DegS{sup {Delta}PDZ} and produce an enzyme that displays hyperbolic kinetics and degrades substrate with a maximal velocity within error of that for fully activated, intact DegS. Crystal structures of multiple DegS{sup {Delta}PDZ} variants, in functional and non-functional conformations, support a two-state model in which allosteric switching is mediated by changes in specific elements of tertiary structure in the context of an invariant trimeric base. Overall, our results indicate that protein substrates must bind sufficiently tightly and specifically to the functional conformation of DegS{sup {Delta}PDZ} to assist their own degradation. Thus, substrate binding alone may have regulated the activities of ancestral DegS trimers with subsequent fusion of the protease domain to a PDZ domain, resulting in ligand-mediated regulation.

  20. Tidal estimation in the Atlantic and Indian Oceans, 3 deg x 3 deg solution

    NASA Technical Reports Server (NTRS)

    Sanchez, Braulio V.; Rao, Desiraju B.; Steenrod, Stephen D.

    1987-01-01

    An estimation technique was developed to extrapolate tidal amplitudes and phases over entire ocean basins using existing gauge data and the altimetric measurements provided by satellite oceanography. The technique was previously tested. Some results obtained by using a 3 deg by 3 deg grid are presented. The functions used in the interpolation are the eigenfunctions of the velocity (Proudman functions) which are computed numerically from a knowledge of the basin's bottom topography, the horizontal plan form and the necessary boundary conditions. These functions are characteristic of the particular basin. The gravitational normal modes of the basin are computed as part of the investigation; they are used to obtain the theoretical forced solutions for the tidal constituents. The latter can provide the simulated data for the testing of the method and serve as a guide in choosing the most energetic functions for the interpolation.

  1. The Mars opposition effect at 20 deg N. latitude and 20 deg W. longitude

    NASA Technical Reports Server (NTRS)

    Thorpe, T. E.

    1979-01-01

    Low phase angle observations in the Chryse-Acidalia region have been obtained by the Viking Orbiter 1 spacecraft under clearer atmospheric conditions than reported earlier. A variety of surface features were recorded, e.g., crater streaks, dark and bright patches. Several findings for this scene include: an abrupt brightness increase (10%) was found at phase angles less than 3 deg, an effect dependent on surface albedo and possibly particle distribution; a slight weakening of reflectance surge with decreasing wavelengths; a larger opposition effect for features of high albedo was recorded; and a greater reddening with increased phase angle took place for low albedo regions. Both reflectance and contrast values are provided at three wavelengths as a function of phase angle from 0.15 to 20 deg.

  2. Tropospheric ozone at 45 deg S

    NASA Technical Reports Server (NTRS)

    Matthews, W. Andrew

    1994-01-01

    In August of 1986 a program was initiated to measure atmospheric ozone profiles at mid-latitudes in the Southern Hemisphere by flying ECC ozonesondes on a regular basis from the DSIR Physical Sciences Atmospheric Laboratory at Lauder, New Zealand, 45 deg S. Flights since that time have been performed on a regular basis at the rate of two flights per week during the 5 month period August to December, the time of maximum variability at mid-latitudes, and once per week for the remainder of the year. These data, consisting now of more than 400 profiles has been analyzed and the free troposphere portion of the profiles binned as 1km slabs. These data have been combined to form a seasonal average values for each season of each year in 2 km slabs and the variation observed in these seasonal averages is the basis of this paper. A biennial component is apparent in these data and the lack of any increasing trend over this 5 year period is contrasted with that measured at similar latitudes in the Northern Hemisphere over the same period.

  3. An acoustic study of Deg Xinag fricatives

    NASA Astrophysics Data System (ADS)

    Wright, Richard; Hargus, Sharon; Miller, Julia

    2005-04-01

    Few studies have looked at the acoustic properties of fricatives in Native American languages. Notable exceptions are McDonough (2003) on Navajo, and Gordon, Barthmaier, and Sands (2002), which examined a variety of languages, including several Native American ones. In Deg Xinag, an endangered Athabaskan language spoken in Alaska, there are eight places of articulation for voiceless fricatives [a relatively large phonetic inventory, according to Maddieson (1984)], including some rarely studied place contrasts (e.g. alveolar versus retroflex). In this study, pre- and post-vocalic fricatives were digitally recorded in the field from eight speakers (two males, six females) using a head-mounted mic to control for distance from the source. The segmental context was also controlled for, the neighboring vowel being [a] in all cases. Each speaker produced four repetitions of each word. The first four spectral moments, lowest spectral peak, and the three loudest spectral peaks were measured at the midpoint of each fricative, and each speaker's average for each of the measures was calculated. In this poster, qualitative results in the form of spectrographic analysis will be presented. Repeated measures ANOVA for each of the quantitative measures will also be presented. [Work supported by NSF.

  4. Noise measurements for a twin-engine commercial jet aircraft during 3 deg approaches and level flyovers

    NASA Technical Reports Server (NTRS)

    Hastings, E. C., Jr.; Shanks, R. E.; Mueller, A. W.

    1976-01-01

    Noise measurements have been made with a twin-engine commercial jet aircraft making 3 deg approaches and level flyovers. The flight-test data showed that, in the standard 3 deg approach configuration with 40 deg flaps, effective perceived noise level (EPNL) had a value of 109.5 effective perceived noise decibels (EPNdB). This result was in agreement with unpublished data obtained with the same type of aircraft during noise certification tests; the 3 deg approaches made with 30 deg flaps and slightly reduced thrust reduced the EPNL value by 1 EPNdB. Extended center-line noise determined during the 3 deg approaches with 40 deg flaps showed that the maximum reference A-weighted sound pressure level (LA,max)ref varied from 100.0 A-weighted decibels 2.01 km (108 n. mi.) from the threshold to 87.4 db(A) at 6.12 km (3.30 n. mi.) from the threshold. These test values were about 3 db(A) higher than estimates used for comparison. The test data along the extended center line during approaches with 30 deg flaps were 1 db(A) lower than those for approaches with 40 deg flaps. Flight-test data correlating (LA,max)ref with thrust at altitudes of 122 m (400 ft) and 610 m (2000 ft) were in agreement with reference data used for comparison.

  5. OMP Peptides Activate the DegS Stress-Sensor Protease by a Relief of Inhibition Mechanism

    SciTech Connect

    Sohn, Jungsan; Grant, Robert A.; Sauer, Robert T.; MIT

    2010-03-19

    In the E. coli periplasm, C-terminal peptides of misfolded outer-membrane porins (OMPs) bind to the PDZ domains of the trimeric DegS protease, triggering cleavage of a transmembrane regulator and transcriptional activation of stress genes. We show that an active-site DegS mutation partially bypasses the requirement for peptide activation and acts synergistically with mutations that disrupt contacts between the protease and PDZ domains. Biochemical results support an allosteric model, in which these mutations, active-site modification, and peptide/substrate binding act in concert to stabilize proteolytically active DegS. Cocrystal structures of DegS in complex with different OMP peptides reveal activation of the protease domain with varied conformations of the PDZ domain and without specific contacts from the bound OMP peptide. Taken together, these results indicate that the binding of OMP peptides activates proteolysis principally by relieving inhibitory contacts between the PDZ domain and the protease domain of DegS.

  6. Clementine High Resolution Camera Mosaicking Project. Volume 2; CL 6002; 0 deg S to 80 deg S Latitude, 0 deg E to 30 deg E Longitude; 1

    NASA Technical Reports Server (NTRS)

    Malin, Michael; Revine, Michael; Boyce, Joseph M. (Technical Monitor)

    1998-01-01

    This compact disk (CD) is part of the Malin Space Science Systems (MSSS) effort to mosaic Clementine I high resolution (HiRes) camera lunar images. These mosaics were developed through calibration and semi-automated registration against the recently released geometrically and photometrically controlled Ultraviolet/Visible (UV/Vis) Basemap Mosaic, which is available through the PDS, as CD-ROM volumes CL_3001-3015. The HiRes mosaics are compiled from non-uniformity corrected, 750 nanometer ("D") filter high resolution observations from the HiRes imaging system onboard the Clementine Spacecraft. These mosaics are spatially warped using the sinusoidal equal-area projection at a scale of 20 m/pixel. The geometric control is provided by the 100 m/pixel U.S. Geological Survey (USGS) Clementine Basemap Mosaic compiled from the 750 nm Ultraviolet/Visible Clementine imaging system. Calibration was achieved by removing the image nonuniformity largely caused by the HiRes system's light intensifier. Also provided are offset and scale factors, achieved by a fit of the HiRes data to the corresponding photometrically calibrated UV/Vis basemap that approximately transform the 8-bit HiRes data to photometric units. The mosaics on this CD were compiled from sub-polar data (latitudes 80 degrees South to 80 degrees North; -80 to +80) within the longitude range 0-30 deg E. The mosaics are divided into tiles that cover approximately 1.75 degrees of latitude and span the longitude range of the mosaicked frames. Images from a given orbit are map projected using the orbit's nominal central latitude. This CD contains ancillary data files that support the HiRes mosaic. These files include browse images with UV/Vis context stored in a Joint Photographic Experts Group (JPEG) format, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the "FILES

  7. Clementine High Resolution Camera Mosaicking Project. Volume 15; CL 6015; 0 deg S to 80 deg S Latitude, 270 deg E to 300 deg E Longitude; 1

    NASA Technical Reports Server (NTRS)

    Malin, Michael; Revine, Michael; Boyce, Joseph M. (Technical Monitor)

    1998-01-01

    This compact disk (CD) is part of the Malin Space Science Systems (MSSS) effort to mosaic Clementine I high resolution (HiRes) camera lunar images. These mosaics were developed through calibration and semi-automated registration against the recently released geometrically and photometrically controlled Ultraviolet/Visible (UV/Vis) Basemap Mosaic, which is available through the PDS, as CD-ROM volumes CL_3001-3015. The HiRes mosaics are compiled from non-uniformity corrected, 750 nanometer ("D") filter high resolution observations from the HiRes imaging system onboard the Clementine Spacecraft. These mosaics are spatially warped using the sinusoidal equal-area projection at a scale of 20 m/pixel. The geometric control is provided by the 100 m/pixel U. S. Geological Survey (USGS) Clementine Basemap Mosaic compiled from the 750 nm Ultraviolet/Visible Clementine imaging system. Calibration was achieved by removing the image nonuniformity largely caused by the HiRes system's light intensifier. Also provided are offset and scale factors, achieved by a fit of the HiRes data to the corresponding photometrically calibrated UV/Vis basemap that approximately transform the 8-bit HiRes data to photometric units. The mosaics on this CD were compiled from sub-polar data (latitudes 80 degrees South to 80 degrees North; -80 to +80) within the longitude range 0-30 deg E. The mosaics are divided into tiles that cover approximately 1.75 degrees of latitude and span the longitude range of the mosaicked frames. Images from a given orbit are map projected using the orbit's nominal central latitude. This CD contains ancillary data files that support the HiRes mosaic. These files include browse images with UV/Vis context stored in a Joint Photographic Experts Group (JPEG) format, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the "FILES

  8. Clementine High Resolution Camera Mosaicking Project. Volume 16; CL 6016; 0 deg N to 80 deg N Latitude, 300 deg E to 330 deg E Longitude; 1

    NASA Technical Reports Server (NTRS)

    Malin, Michael; Revine, Michael; Boyce, Joseph M. (Technical Monitor)

    1998-01-01

    This compact disk (CD) is part of the Malin Space Science Systems (MSSS) effort to mosaic Clementine I high resolution (HiRes) camera lunar images. These mosaics were developed through calibration and semi-automated registration against the recently released geometrically and photometrically controlled Ultraviolet/Visible (UV/Vis) Basemap Mosaic, which is available through the PDS, as CD-ROM volumes CL_3001-3015. The HiRes mosaics are compiled from non-uniformity corrected, 750 nanometer ("D") filter high resolution observations from the HiRes imaging system onboard the Clementine Spacecraft. These mosaics are spatially warped using the sinusoidal equal-area projection at a scale of 20 m/pixel. The geometric control is provided by the 100 m/pixel U.S. Geological Survey (USGS) Clementine Basemap Mosaic compiled from the 750 nm Ultraviolet/Visible Clementine imaging system. Calibration was achieved by removing the image nonuniformity largely caused by the HiRes system's light intensifier. Also provided are offset and scale factors, achieved by a fit of the HiRes data to the corresponding photometrically calibrated UV/Vis basemap that approximately transform the 8-bit HiRes data to photometric units. The mosaics on this CD were compiled from sub-polar data (latitudes 80 degrees South to 80 degrees North; -80 to +80) within the longitude range 0-30 deg E. The mosaics are divided into tiles that cover approximately 1.75 degrees of latitude and span the longitude range of the mosaicked frames. Images from a given orbit are map projected using the orbit's nominal central latitude. This CD contains ancillary data files that support the HiRes mosaic. These files include browse images with UV/Vis context stored in a Joint Photographic Experts Group (JPEG) format, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the "FILES

  9. Clementine High Resolution Camera Mosaicking Project. Volume 3; CL 6003; 0 deg N to 80 deg N Latitude, 30 deg E to 60 deg E Longitude; 1

    NASA Technical Reports Server (NTRS)

    Malin, Michael; Revine, Michael; Boyce, Joseph (Technical Monitor)

    1998-01-01

    This compact disk (CD) is part of the Malin Space Science Systems (MSSS) effort to mosaic Clementine I high resolution (HiRes) camera lunar images. These mosaics were developed through calibration and semi-automated registration against the recently released geometrically and photometrically controlled Ultraviolet/Visible (UV/Vis) Basemap Mosaic, which is available through the PDS, as CD-ROM volumes CL_3001-3015. The HiRes mosaics are compiled from non-uniformity corrected, 750 nanometer ("D") filter high resolution observations from the HiRes imaging system onboard the Clementine Spacecraft. These mosaics are spatially warped using the sinusoidal equal-area projection at a scale of 20 m/pixel. The geometric control is provided by the 100 m/pixel U.S. Geological Survey (USGS) Clementine Basemap Mosaic compiled from the 750 nm Ultraviolet/Visible Clementine imaging system. Calibration was achieved by removing the image nonuniformity largely caused by the HiRes system's light intensifier. Also provided are offset and scale factors, achieved by a fit of the HiRes data to the corresponding photometrically calibrated UV/Vis basemap that approximately transform the 8-bit HiRes data to photometric units. The mosaics on this CD were compiled from sub-polar data (latitudes 80 degrees South to 80 degrees North; -80 to +80) within the longitude range 0-30 deg E. The mosaics are divided into tiles that cover approximately 1.75 degrees of latitude and span the longitude range of the mosaicked frames. Images from a given orbit are map projected using the orbit's nominal central latitude. This CD contains ancillary data files that support the HiRes mosaic. These files include browse images with UV/Vis context stored in a Joint Photographic Experts Group (JPEG) format, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the "FILES

  10. Clementine High Resolution Camera Mosaicking Project. Volume 18; CL 6018; 80 deg N to 80 deg S Latitude, 330 deg E to 360 deg E Longitude; 1

    NASA Technical Reports Server (NTRS)

    Malin, Michael; Revine, Michael; Boyce, Joseph M. (Technical Monitor)

    1998-01-01

    This compact disk (CD) is part of the Malin Space Science Systems (MSSS) effort to mosaic Clementine I high resolution (HiRes) camera lunar images. These mosaics were developed through calibration and semi-automated registration against the recently released geometrically and photometrically controlled Ultraviolet/Visible (UV/Vis) Basemap Mosaic, which is available through the PDS, as CD-ROM volumes CL_3001-3015. The HiRes mosaics are compiled from non-uniformity corrected, 750 nanometer ("D") filter high resolution observations from the HiRes imaging system onboard the Clementine Spacecraft. These mosaics are spatially warped using the sinusoidal equal-area projection at a scale of 20 m/pixel. The geometric control is provided by the 100 m/pixel U. S. Geological Survey (USGS) Clementine Basemap Mosaic compiled from the 750 nm Ultraviolet/Visible Clementine imaging system. Calibration was achieved by removing the image nonuniformity largely caused by the HiRes system's light intensifier. Also provided are offset and scale factors, achieved by a fit of the HiRes data to the corresponding photometrically calibrated UV/Vis basemap that approximately transform the 8-bit HiRes data to photometric units. The mosaics on this CD were compiled from sub-polar data (latitudes 80 degrees South to 80 degrees North; -80 to +80) within the longitude range 0-30 deg E. The mosaics are divided into tiles that cover approximately 1.75 degrees of latitude and span the longitude range of the mosaicked frames. Images from a given orbit are map projected using the orbit's nominal central latitude. This CD contains ancillary data files that support the HiRes mosaic. These files include browse images with UV/Vis context stored in a Joint Photographic Experts Group (JPEG) format, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the "FILES

  11. Clementine High Resolution Camera Mosaicking Project. Volume 12; CL 6012; 0 deg N to 80 deg N Latitude, 240 deg to 270 deg E Longitude; 1

    NASA Technical Reports Server (NTRS)

    Malin, Michael; Revine, Michael; Boyce, Joseph M. (Technical Monitor)

    1998-01-01

    This compact disk (CD) is part of the Malin Space Science Systems (MSSS) effort to mosaic Clementine I high resolution (HiRes) camera lunar images. These mosaics were developed through calibration and semi-automated registration against the recently released geometrically and photometrically controlled Ultraviolet/Visible (UV/Vis) Basemap Mosaic, which is available through the PDS, as CD-ROM volumes CL_3001-3015. The HiRes mosaics are compiled from non-uniformity corrected, 750 nanometer ("D") filter high resolution observations from the HiRes imaging system onboard the Clementine Spacecraft. These mosaics are spatially warped using the sinusoidal equal-area projection at a scale of 20 m/pixel. The geometric control is provided by the 100 m/pixel U.S. Geological Survey (USGS) Clementine Basemap Mosaic compiled from the 750 nm Ultraviolet/Visible Clementine imaging system. Calibration was achieved by removing the image nonuniformity largely caused by the HiRes system's light intensifier. Also provided are offset and scale factors, achieved by a fit of the HiRes data to the corresponding photometrically calibrated UV/Vis basemap that approximately transform the 8-bit HiRes data to photometric units. The mosaics on this CD were compiled from sub-polar data (latitudes 80 degrees South to 80 degrees North; -80 to +80) within the longitude range 0-30 deg E. The mosaics are divided into tiles that cover approximately 1.75 degrees of latitude and span the longitude range of the mosaicked frames. Images from a given orbit are map projected using the orbit's nominal central latitude. This CD contains ancillary data files that support the HiRes mosaic. These files include browse images with UV/Vis context stored in a Joint Photographic Experts Group (JPEG) format, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the "FILES

  12. Clementine High Resolution Camera Mosaicking Project. Volume 7; CL 6007; 80 deg N to 80 deg S Latitude, 120 deg E to 150 deg E Longitude; 1

    NASA Technical Reports Server (NTRS)

    Malin, Michael; Revine, Michael; Boyce, Joseph M. (Technical Monitor)

    1998-01-01

    This compact disk (CD) is part of the Malin Space Science Systems (MSSS) effort to mosaic Clementine I high resolution (HiRes) camera lunar images. These mosaics were developed through calibration and semi-automated registration against the recently released geometrically and photometrically controlled Ultraviolet/Visible (UV/Vis) Basemap Mosaic, which is available through the PDS, as CD-ROM volumes CL_3001-3015. The HiRes mosaics are compiled from non-uniformity corrected, 750 nanometer ("D") filter high resolution observations from the HiRes imaging system onboard the Clementine Spacecraft. These mosaics are spatially warped using the sinusoidal equal-area projection at a scale of 20 m/pixel. The geometric control is provided by the 100 m/pixel U.S. Geological Survey (USGS) Clementine Basemap Mosaic compiled from the 750 nm Ultraviolet/Visible Clementine imaging system. Calibration was achieved by removing the image nonuniformity largely caused by the HiRes system's light intensifier. Also provided are offset and scale factors, achieved by a fit of the HiRes data to the corresponding photometrically calibrated UV/Vis basemap that approximately transform the 8-bit HiRes data to photometric units. The mosaics on this CD were compiled from sub-polar data (latitudes 80 degrees South to 80 degrees North; -80 to +80) within the longitude range 0-30 deg E. The mosaics are divided into tiles that cover approximately 1.75 degrees of latitude and span the longitude range of the mosaicked frames. Images from a given orbit are map projected using the orbit's nominal central latitude. This CD contains ancillary data files that support the HiRes mosaic. These files include browse images with UV/Vis context stored in a Joint Photographic Experts Group (JPEG) format, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the "FILES

  13. Clementine High Resolution Camera Mosaicking Project. Volume 7; CL 6007; 80 deg N to 80 deg S Latitude; 120 deg E to 150 deg E Longitude; 1

    NASA Technical Reports Server (NTRS)

    Malin, Michael; Revine, Michael; Boyce, Joseph M. (Technical Monitor)

    1998-01-01

    This compact disk (CD) is part of the Malin Space Science Systems (MSSS) effort to mosaic Clementine I high resolution (HiRes) camera lunar images. These mosaics were developed through calibration and semi-automated registration against the recently released geometrically and photometrically controlled Ultraviolet/Visible (UV/Vis) Basemap Mosaic, which is available through the PDS, as CD-ROM volumes CL_3001-3015. The HiRes mosaics are compiled from non-uniformity corrected, 750 nanometer ("D") filter high resolution observations from the HiRes imaging system onboard the Clementine Spacecraft. These mosaics are spatially warped using the sinusoidal equal-area projection at a scale of 20 m/pixel. The geometric control is provided by the 100 m/pixel U.S. Geological Survey (USGS) Clementine Basemap Mosaic compiled from the 750 nm Ultraviolet/Visible Clementine imaging system. Calibration was achieved by removing the image nonuniformity largely caused by the HiRes system's light intensifier. Also provided are offset and scale factors, achieved by a fit of the HiRes data to the corresponding photometrically calibrated UV/Vis basemap that approximately transform the 8-bit HiRes data to photometric units. The mosaics on this CD were compiled from sub-polar data (latitudes 80 degrees South to 80 degrees North; -80 to +80) within the longitude range 0-30 deg E. The mosaics are divided into tiles that cover approximately 1.75 degrees of latitude and span the longitude range of the mosaicked frames. Images from a given orbit are map projected using the orbit's nominal central latitude. This CD contains ancillary data files that support the HiRes mosaic. These files include browse images with UV/Vis context stored in a Joint Photographic Experts Group (JPEG) format, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the "FILES

  14. Clementine High Resolution Camera Mosaicking Project. Volume 5; CL 6005, 80 deg N to 80 deg S Latitude, 60 deg E to 90 deg E Longitude; 1

    NASA Technical Reports Server (NTRS)

    Malin, Michael; Revine, Michael; Boyce, Joseph M. (Technical Monitor)

    1998-01-01

    This compact disk (CD) is part of the Malin Space Science Systems (MSSS) effort to mosaic Clementine I high resolution (HiRes) camera lunar images. These mosaics were developed through calibration and semi-automated registration against the recently released geometrically and photometrically controlled Ultraviolet/Visible (UV/Vis) Basemap Mosaic, which is available through the PDS, as CD-ROM volumes CL_3001-3015. The HiRes mosaics are compiled from non-uniformity corrected, 750 nanometer ("D") filter high resolution observations from the HiRes imaging system onboard the Clementine Spacecraft. These mosaics are spatially warped using the sinusoidal equal-area projection at a scale of 20 m/pixel. The geometric control is provided by the 100 m/pixel U.S. Geological Survey (USGS) Clementine Basemap Mosaic compiled from the 750 nm Ultraviolet/Visible Clementine imaging system. Calibration was achieved by removing the image nonuniformity largely caused by the HiRes system's light intensifier. Also provided are offset and scale factors, achieved by a fit of the HiRes data to the corresponding photometrically calibrated UV/Vis basemap that approximately transform the 8-bit HiRes data to photometric units. The mosaics on this CD were compiled from sub-polar data (latitudes 80 degrees South to 80 degrees North; -80 to +80) within the longitude range 0-30 deg E. The mosaics are divided into tiles that cover approximately 1.75 degrees of latitude and span the longitude range of the mosaicked frames. Images from a given orbit are map projected using the orbit's nominal central latitude. This CD contains ancillary data files that support the HiRes mosaic. These files include browse images with UV/Vis context stored in a Joint Photographic Experts Group (JPEG) format, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the "FILES

  15. Clementine High Resolution Camera Mosaicking Project. Volume 9; CL 6009; 80 deg N to 80 deg S Latitude, 180 deg to 210 deg E Longitude; 1

    NASA Technical Reports Server (NTRS)

    Malin, Michael; Revine, Michael; Boyce, Joseph M. (Technical Monitor)

    1998-01-01

    This compact disk (CD) is part of the Malin Space Science Systems (MSSS) effort to mosaic Clementine I high resolution (HiRes) camera lunar images. These mosaics were developed through calibration and semi-automated registration against the recently released geometrically and photometrically controlled Ultraviolet/Visible (UV/Vis) Basemap Mosaic, which is available through the PDS, as CD-ROM volumes CL_3001-3015. The HiRes mosaics are compiled from non-uniformity corrected, 750 nanometer ("D") filter high resolution observations from the HiRes imaging system onboard the Clementine Spacecraft. These mosaics are spatially warped using the sinusoidal equal-area projection at a scale of 20 m/pixel. The geometric control is provided by the 100 m/pixel U.S. Geological Survey (USGS) Clementine Basemap Mosaic compiled from the 750 nm Ultraviolet/Visible Clementine imaging system. Calibration was achieved by removing the image nonuniformity largely caused by the HiRes system's light intensifier. Also provided are offset and scale factors, achieved by a fit of the HiRes data to the corresponding photometrically calibrated UV/Vis basemap that approximately transform the 8-bit HiRes data to photometric units. The mosaics on this CD were compiled from sub-polar data (latitudes 80 degrees South to 80 degrees North; -80 to +80) within the longitude range 0-30 deg E. The mosaics are divided into tiles that cover approximately 1.75 degrees of latitude and span the longitude range of the mosaicked frames. Images from a given orbit are map projected using the orbit's nominal central latitude. This CD contains ancillary data files that support the HiRes mosaic. These files include browse images with UV/Vis context stored in a Joint Photographic Experts Group (JPEG) format, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the "FILES

  16. Clementine High Resolution Camera Mosaicking Project. Volume 1; CL 6001; 0 deg N to 80 deg N Latitude, 0 deg E to 30 deg E Longitude; 1

    NASA Technical Reports Server (NTRS)

    Malin, Michael; Revine, Michael; Boyce, Joseph M. (Technical Monitor)

    1998-01-01

    This compact disk (CD) is part of the Malin Space Science Systems (MSSS) effort to mosaic Clementine I high resolution (HiRes) camera lunar images. These mosaics were developed through calibration and semi-automated registration against the recently released geometrically and photometrically controlled Ultraviolet/Visible (UV/Vis) Basemap Mosaic, which is available through the PDS, as CD-ROM volumes CL_3001-3015. The HiRes mosaics are compiled from non-uniformity corrected, 750 nanometer ("D") filter high resolution observations from the HiRes imaging system onboard the Clementine Spacecraft. These mosaics are spatially warped using the sinusoidal equal-area projection at a scale of 20 m/pixel. The geometric control is provided by the 100 m/pixel U.S. Geological Survey (USGS) Clementine Basemap Mosaic compiled from the 750 nm Ultraviolet/Visible Clementine imaging system. Calibration was achieved by removing the image nonuniformity largely caused by the HiRes system's light intensifier. Also provided are offset and scale factors, achieved by a fit of the HiRes data to the corresponding photometrically calibrated UV/Vis basemap that approximately transform the 8-bit HiRes data to photometric units. The mosaics on this CD were compiled from sub-polar data (latitudes 80 degrees South to 80 degrees North; -80 to +80) within the longitude range 0-30 deg E. The mosaics are divided into tiles that cover approximately 1.75 degrees of latitude and span the longitude range of the mosaicked frames. Images from a given orbit are map projected using the orbit's nominal central latitude. This CD contains ancillary data files that support the HiRes mosaic. These files include browse images with UV/Vis context stored in a Joint Photographic Experts Group (JPEG) format, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the "FILES

  17. Clementine High Resolution Camera Mosaicking Project. Volume 14; CL 6014; 0 deg N to 80 deg N Latitude, 270 deg E to 300 deg E Longitude; 1

    NASA Technical Reports Server (NTRS)

    Malin, Michael; Revine, Michael; Boyce, Joseph M. (Technical Monitor)

    1998-01-01

    This compact disk (CD) is part of the Malin Space Science Systems (MSSS) effort to mosaic Clementine I high resolution (HiRes) camera lunar images. These mosaics were developed through calibration and semi-automated registration against the recently released geometrically and photometrically controlled Ultraviolet/Visible (UV/Vis) Basemap Mosaic, which is available through the PDS, as CD-ROM volumes CL_3001-3015. The HiRes mosaics are compiled from non-uniformity corrected, 750 nanometer ("D") filter high resolution observations from the HiRes imaging system onboard the Clementine Spacecraft. These mosaics are spatially warped using the sinusoidal equal-area projection at a scale of 20 m/pixel. The geometric control is provided by the 100 m/pixel U.S. Geological Survey (USGS) Clementine Basemap Mosaic compiled from the 750 nm Ultraviolet/Visible Clementine imaging system. Calibration was achieved by removing the image nonuniformity largely caused by the HiRes system's light intensifier. Also provided are offset and scale factors, achieved by a fit of the HiRes data to the corresponding photometrically calibrated UV/Vis basemap that approximately transform the 8-bit HiRes data to photometric units. The mosaics on this CD were compiled from sub-polar data (latitudes 80 degrees South to 80 degrees North; -80 to +80) within the longitude range 0-30 deg E. The mosaics are divided into tiles that cover approximately 1.75 degrees of latitude and span the longitude range of the mosaicked frames. Images from a given orbit are map projected using the orbit's nominal central latitude. This CD contains ancillary data files that support the HiRes mosaic. These files include browse images with UV/Vis context stored in a Joint Photographic Experts Group (JPEG) format, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the "FILES

  18. Clementine High Resolution Camera Mosaicking Project. Volume 4; CL 6004; 0 deg S to 80 deg S Latitude, 30 deg E to 60 deg E Longitude; 1

    NASA Technical Reports Server (NTRS)

    Malin, Michael; Revine, Michael; Boyce, Joseph M. (Technical Monitor)

    1998-01-01

    This compact disk (CD) is part of the Malin Space Science Systems (MSSS) effort to mosaic Clementine I high resolution (HiRes) camera lunar images. These mosaics were developed through calibration and semi-automated registration against the recently released geometrically and photometrically controlled Ultraviolet/Visible (UV/Vis) Basemap Mosaic, which is available through the PDS, as CD-ROM volumes CL_3001-3015. The HiRes mosaics are compiled from non-uniformity corrected, 750 nanometer ("D") filter high resolution observations from the HiRes imaging system onboard the Clementine Spacecraft. These mosaics are spatially warped using the sinusoidal equal-area projection at a scale of 20 m/pixel. The geometric control is provided by the 100 m/pixel U.S. Geological Survey (USGS) Clementine Basemap Mosaic compiled from the 750 nm Ultraviolet/Visible Clementine imaging system. Calibration was achieved by removing the image nonuniformity largely caused by the HiRes system's light intensifier. Also provided are offset and scale factors, achieved by a fit of the HiRes data to the corresponding photometrically calibrated UV/Vis basemap that approximately transform the 8-bit HiRes data to photometric units. The mosaics on this CD were compiled from sub-polar data (latitudes 80 degrees South to 80 degrees North; -80 to +80) within the longitude range 0-30 deg E. The mosaics are divided into tiles that cover approximately 1.75 degrees of latitude and span the longitude range of the mosaicked frames. Images from a given orbit are map projected using the orbit's nominal central latitude. This CD contains ancillary data files that support the HiRes mosaic. These files include browse images with UV/Vis context stored in a Joint Photographic Experts Group (JPEG) format, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the "FILES

  19. Clementine High Resolution Camera Mosaicking Project. Volume 10; CL 6010; 0 deg N to 80 deg N Latitude, 210 deg E to 240 deg E Longitude; 1

    NASA Technical Reports Server (NTRS)

    Malin, Michael; Revine, Michael; Boyce, Joseph M. (Technical Monitor)

    1998-01-01

    This compact disk (CD) is part of the Malin Space Science Systems (MSSS) effort to mosaic Clementine I high resolution (HiRes) camera lunar images. These mosaics were developed through calibration and semi-automated registration against the recently released geometrically and photometrically controlled Ultraviolet/Visible (UV/Vis) Basemap Mosaic, which is available through the PDS, as CD-ROM volumes CL_3001-3015. The HiRes mosaics are compiled from non-uniformity corrected, 750 nanometer ("D") filter high resolution observations from the HiRes imaging system onboard the Clementine Spacecraft. These mosaics are spatially warped using the sinusoidal equal-area projection at a scale of 20 m/pixel. The geometric control is provided by the 100 m/pixel U.S. Geological Survey (USGS) Clementine Basemap Mosaic compiled from the 750 nm Ultraviolet/Visible Clementine imaging system. Calibration was achieved by removing the image nonuniformity largely caused by the HiRes system's light intensifier. Also provided are offset and scale factors, achieved by a fit of the HiRes data to the corresponding photometrically calibrated UV/Vis basemap that approximately transform the 8-bit HiRes data to photometric units. The mosaics on this CD were compiled from sub-polar data (latitudes 80 degrees South to 80 degrees North; -80 to +80) within the longitude range 0-30 deg E. The mosaics are divided into tiles that cover approximately 1.75 degrees of latitude and span the longitude range of the mosaicked frames. Images from a given orbit are map projected using the orbit's nominal central latitude. This CD contains ancillary data files that support the HiRes mosaic. These files include browse images with UV/Vis context stored in a Joint Photographic Experts Group (JPEG) format, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the "FILES

  20. Clementine High Resolution Camera Mosaicking Project. Volume 13; CL 6013; 0 deg S to 80 deg S Latitude, 240 deg to 270 deg E Longitude; 1

    NASA Technical Reports Server (NTRS)

    Malin, Michael; Revine, Michael; Boyce, Joseph M. (Technical Monitor)

    1998-01-01

    This compact disk (CD) is part of the Malin Space Science Systems (MSSS) effort to mosaic Clementine I high resolution (HiRes) camera lunar images. These mosaics were developed through calibration and semi-automated registration against the recently released geometrically and photometrically controlled Ultraviolet/Visible (UV/Vis) Basemap Mosaic, which is available through the PDS, as CD-ROM volumes CL_3001-3015. The HiRes mosaics are compiled from non-uniformity corrected, 750 nanometer ("D") filter high resolution observations from the HiRes imaging system onboard the Clementine Spacecraft. These mosaics are spatially warped using the sinusoidal equal-area projection at a scale of 20 m/pixel. The geometric control is provided by the 100 m/pixel U.S. Geological Survey (USGS) Clementine Basemap Mosaic compiled from the 750 nm Ultraviolet/Visible Clementine imaging system. Calibration was achieved by removing the image nonuniformity largely caused by the HiRes system's light intensifier. Also provided are offset and scale factors, achieved by a fit of the HiRes data to the corresponding photometrically calibrated UV/Vis basemap that approximately transform the 8-bit HiRes data to photometric units. The mosaics on this CD were compiled from sub-polar data (latitudes 80 degrees South to 80 degrees North; -80 to +80) within the longitude range 0-30 deg E. The mosaics are divided into tiles that cover approximately 1.75 degrees of latitude and span the longitude range of the mosaicked frames. Images from a given orbit are map projected using the orbit's nominal central latitude. This CD contains ancillary data files that support the HiRes mosaic. These files include browse images with UV/Vis context stored in a Joint Photographic Experts Group (JPEG) format, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the "FILES

  1. DegP Chaperone Suppresses Toxic Inner Membrane Translocation Intermediates.

    PubMed

    Braselmann, Esther; Chaney, Julie L; Champion, Matthew M; Clark, Patricia L

    2016-01-01

    The periplasm of Gram-negative bacteria includes a variety of molecular chaperones that shepherd the folding and targeting of secreted proteins. A central player of this quality control network is DegP, a protease also suggested to have a chaperone function. We serendipitously discovered that production of the Bordetella pertussis autotransporter virulence protein pertactin is lethal in Escherichia coli ΔdegP strains. We investigated specific contributions of DegP to secretion of pertactin as a model system to test the functions of DegP in vivo. The DegP chaperone activity was sufficient to restore growth during pertactin production. This chaperone dependency could be relieved by changing the pertactin signal sequence: an E. coli signal sequence leading to co-translational inner membrane (IM) translocation was sufficient to suppress lethality in the absence of DegP, whereas an E. coli post-translational signal sequence was sufficient to recapitulate the lethal phenotype. These results identify a novel connection between the DegP chaperone and the mechanism used to translocate a protein across the IM. Lethality coincided with loss of periplasmic proteins, soluble σE, and proteins regulated by this essential stress response. These results suggest post-translational IM translocation can lead to the formation of toxic periplasmic folding intermediates, which DegP can suppress. PMID:27626276

  2. SSF1deg-Day Terra Ed4

    Atmospheric Science Data Center

    2016-06-08

    ... and Order:  Reverb   Reverb Tutorial Subset/Visualization Tool:  CERES Order Tool Search and Order:  ASDC Order ... Documents:  Detailed CERES SSF1deg-lite Product Information Data Products Catalog: DPC_SSF1deg-Day_Ed4_R5V1 ...

  3. SYN1deg-M3Hour Ed3A

    Atmospheric Science Data Center

    2016-06-08

    ... and Order:  Reverb   Reverb Tutorial Subset/Visualization Tool: CERES Order Tool Order Data:  ... Detailed CERES SYN1deg Product Information Data Products Catalog:  DPC_SYN1deg-M3Hour_R5V1 ...

  4. Characterization of Queso Fresco during storage at 4 and 10 deg C

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The chemical, rheological, textural, functional, and sensory aspects of Queso Fresco, a popular Hispanic cheese variety made without starter culture and with a pH over 6, were evaluated during storage at 4 and 10 deg C. Decreases in lactose and pH levels were observed and attributed to activity by...

  5. The Prevalence of the 22 deg Halo in Cirrus Clouds

    NASA Technical Reports Server (NTRS)

    Diedenhoven, vanBastiaan

    2014-01-01

    Halos at 22 deg from the sun attributed to randomly-orientated, pristine hexagonal crystals are frequently observed through ice clouds. These frequent sightings of halos formed by pristine crystals pose an apparent inconsistency with the dominance of distorted, nonpristine ice crystals indicated by in situ and remote sensing data. Furthermore, the 46 deg halo, which is associated with pristine hexagonal crystals as well, is observed far less frequently than the 22 deg halo. Considering that plausible mechanisms that could cause crystal distortion such as aggregation, sublimation, riming and collisions are stochastic processes that likely lead to distributions of crystals with varying distortion levels, here the presence of the 22 deg and 46 deg halo features in phase functions of mixtures of pristine and distorted hexagonal ice crystals is examined. We conclude that the 22 deg halo feature is generally present if the contribution by pristine crystals to the total scattering cross section is greater than only about 10% in the case of compact particles or columns, and greater than about 40% for plates. The 46 deg halo feature is present only if the mean distortion level is low and the contribution of pristine crystals to the total scattering cross section is above about 20%, 50% and 70%, in the case of compact crystals, plates and columns, respectively. These results indicate that frequent sightings of 22 deg halos are not inconsistent with the observed dominance of distorted, non-pristine ice crystals. Furthermore, the low mean distortion levels and large contributions by pristine crystals needed to produce the 461 halo features provide a potential explanation of the common sighting of the 22 deg halo without any detectable 46 deg halo.

  6. Force and moment measurements on a 74 deg delta wing with an apex flap

    NASA Technical Reports Server (NTRS)

    Buter, T. A.; Rao, D. M.

    1984-01-01

    Results are presented of a subsonic experimental investigation of an apex flap concept on a 74 deg swept delta wing with trailing-edge flaps. The apex flap comprised approximately 6 percent of the wing area forward of a transverse hinge, allowing for upward and downward deflection angles from +40 deg to -20 deg. Upward deflection forces leading-edge vortex formation on the apex flap, resulting in an increased lift component on the apex area. The associated nose-up moment balances the nose-down moment due to trailing-edge flaps, resulting in sizeable increase in the trimmed lift coefficient particularly at low angles of attack. Nose-down apex deflection may be used to augment the pitch control for rapid recovery from high-alpha maneuvers. This report presents the balance data without analysis.

  7. The distribution of luminous stars at (l,b) = (245 deg, 0 deg) in Puppis

    NASA Astrophysics Data System (ADS)

    Reed, B. C.; Fitzgerald, M. P.

    1984-11-01

    Munch (1951, 1954) drew attention to the presence of a concentration of faint OB stars along the galactic equator at l = 245 deg in Puppis. The distribution of OB stars in this field has subsequently been studied by a number of workers. It has now been found that the distribution of OB stars in Puppis is not well established. The present investigation has, therefore, the objective to reexamine all available spectroscopic and photometric data on these OB stars in a systematic fashion, utilizing the method of spectroscopic parallaxes rather than H-beta photometry or ZAMS fitting. Attention is given to interstellar extinction, stellar distribution perpendicular to the Galactic plane, and the stellar density distribution.

  8. Positions of galactic X-ray sources with l/II/ between -20 deg and +6 deg

    NASA Technical Reports Server (NTRS)

    Jernigan, J. G.; Bradt, H. V.; Doxsey, R. E.; Dower, R. G.; Mcclintock, J. E.; Apparao, K. M. V.

    1978-01-01

    The precise positions of nine X-ray sources in the vicinity of the galactic center are reported. The data were obtained as part of the comprehensive survey of the galactic plane performed with the rotating modulation collimator detectors on the SAS-3 X-ray observatory. The sources include the binary X-ray source 4U 1700-37 which has a well established optical counterpart that lies 7 sec from the reported position. The other sources GX 349+2, 4U 1702-42, 4U 1705-44, MX 1716-31, A 1742-294, 4U 1755-33, GX 5-1, and 2S 1803-245 lack established counterparts in other wavelengths. The obtained position for GX 5-1 adds confidence to the radio counterpart proposed by Braes et al. (1972). The reported position for 4U 1755-33 excludes the optical counterpart proposed by Jones et al. (1974).

  9. Column abundance measurements of atmospheric hydroxyl at 45 deg S

    NASA Technical Reports Server (NTRS)

    Wood, S. W.; Keep, D. J.; Burnett, C. R.; Burnett, E. B.

    1994-01-01

    The first Southern Hemisphere measurements of the vertical column abundance of atmospheric hydroxyl (OH) have been obtained at Lauder, New Zealand (45 deg S) with a PEPSIOS instrument measuring the absorption of sunlight at 308 nm. The variation of column OH with solar zenith angle is similar to that measured at other sites. However average annual abundances of OH are about 20% higher than those found by similar measurements at 40 deg N. Minimum OH abundances about 10% less than average levels at 40 deg N, are observed during austral spring. The OH abundance abruptly increases by 30% in early summer and remains at the elevated level until late the following winter.

  10. Full 360 deg phase shifting of injection-locked oscillators

    NASA Astrophysics Data System (ADS)

    Zhang, Xiangdong; Daryoush, Afshin S.

    1993-01-01

    A novel design is presented to produce analog phase shifts of 0 deg to 360 deg in optically controlled oscillators which are subharmonically injection-locked. The proposed concept was analytically described and experimentally demonstrated by producing a 360 deg phase shift in an 8 GHz oscillator that is indirectly optically injection-locked to a 4 GHz subharmonic frequency. This design concept could eliminate the need for switched delay-line phase shifters in T/R modules of optically controlled phased array antennas, thus making the T/R module more compact and efficient.

  11. Periodic variations in stratospheric meridional wind from 20-65 km, at 80 deg N to 8 deg S

    NASA Technical Reports Server (NTRS)

    Nastrom, G. D.; Belmont, A. D.; Dartt, D. G.

    1974-01-01

    The variability of stratospheric meridional winds is examined in both space and time. Height-latitude sections for January along 70 deg E and 90 deg W show a divergence zone above 50 km near 60 deg N and an intense convergence zone 40 km near 50 deg N over North America. This latter structure, with southward winds in the Arctic and northward winds at mid-latitudes over North America, persists from October through April. Tidal winds dominate all other circulation features in summer at all latitudes, and throughout the year at low latitudes. To help understand the observed patterns of variability, long-term periodic features are analyzed. The quasi-biennial oscillation, annual wave, and four-month wave have amplitudes of about 10, 20, and 10 m/sec respectively in the Arctic near 45 km. The phase of the annual wave changes by nearly 180 deg in a narrow zone near 45 deg N. The semiannual wave has an amplitude of 10 m/sec. 50 deg N above 50 km equinoctial phase dates in the region of maximum amplitude. This polar semiannual wave corresponds closely to that previously found in the zonal wind.

  12. CO observations around galactic longitude l=45 deg

    NASA Technical Reports Server (NTRS)

    Israel, F. P.

    1982-01-01

    An area of about 1.5 deg x 2.0 deg, centered on l=45.5 deg and b=0.0 deg, was mapped in the (C-12)O line at intervals of one beamwidth. A total of 22 individual CO cloud complexes was identified; the brightest of these is associated with a massive H I cloud and the H II region complex G45.5+0.1. This object most likely represents a small OB star cluster in its early stages of development. All other H II regions in the area mapped are likewise associated with CO maxima. The survey results indicate a structure of the Sagittarius arm generally in agreement with that derived in earlier studies; they also indicate that the Galaxy as a whole contains of the order of 3500 molecular clouds larger than 10 pc in diameter.

  13. Heating rate measurements over 30 deg and 40 deg (half angle) blunt cones in air and helium in the Langley expansion tube facility

    NASA Technical Reports Server (NTRS)

    Reddy, N. M.

    1980-01-01

    Convective heat transfer measurements, made on the conical portion of spherically blunted cones (30 deg and 40 deg half angle) in an expansion tube are discussed. The test gases used were helium and air; flow velocities were about 6.8 km/sec for helium and about 5.1 km/sec for air. The measured heating rates are compared with calculated results using a viscous shock layer computer code. For air, various techniques to determine flow velocity yielded identical results, but for helium, the flow velocity varied by as much as eight percent depending on which technique was used. The measured heating rates are in satisfactory agreement with calculation for helium, assuming the lower flow velocity, the measurements are significantly greater than theory and the discrepancy increased with increasing distance along the cone.

  14. 1700 deg C optical temperature sensor

    NASA Technical Reports Server (NTRS)

    Mossey, P. W.; Shaffernocker, W. M.; Mulukutla, A. R.

    1986-01-01

    A new gas temperature sensor was developed that shows promise of sufficient ruggedness to be useful as a gas turbine temperature sensor. The sensor is in the form of a single-crystal aluminum oxide ceramic, ground to a cone shape and given an emissive coating. A lens and an optical fiber conduct the thermally emitted light to a remote and near-infrared photodetector assembly. Being optically coupled and passive, the sensor is highly immune to all types of electrical interference. Candidate sensors were analyzed for optical sensor performance, heat transfer characteristics, stress from gas loading. This led to the selection of the conical shape as the most promising for the gas turbine environment. One uncoated and two coated sensing elements were prepared for testing. Testing was conducted to an indicated 1750 C in a propane-air flame. Comparison with the referee optical pyrometer shows an accuracy of + or - 25 C at 1700 C for this initial development. One hundred cycles from room temperature to 1700 C left the sapphire cone intact, but some loss of the platinum, 6% rhodium coating was observed. Several areas for improving the overall performance and durability are identified.

  15. Fatigue resistance of unnotched and post impact(+/- 30 deg/0 deg) 3-D braided composites

    NASA Technical Reports Server (NTRS)

    Portanova, Marc A.

    1994-01-01

    The fatigue resistance of a multiaxial braided (3-D) graphite/expoxy composite in both unnotched and post impacted conditions has been evaluated. The material tested is a (+/- 30/0 deg) multiaxial braid constructed from AS4/12K tow graphite fibers and British Petroleum E905L epoxy resin. These materials were braided as dry preforms and the epoxy was added using a resin transfer molding process (RTM). The unnotched and post-impact specimens were tested in compression-compression fatigue at 10 Hz with a stress ratio of R=10. The unnotched tension-tension fatigue specimens were tested at S Hz with a stress ration of R=0.1. Damage initiation and growth was documented through the application of radiography and ultrasonic through transmission (C-scans). Visible inspection of surface and edge damage was also noted to describe the initiation and progression of damage in these materials. The mechanisms leading to damage initiation were established and failure modes were determined. Stiffness and strength degradation were measured as a function of applied cycles. These 3-D braided composite results were compared to strain levels currently used to design primary structure in commercial aircraft composite components made from prepreg tape and autoclave cured.

  16. Galactic OB associations in the northern Milky Way Galaxy. I - Longitudes 55 deg to 150 deg

    NASA Technical Reports Server (NTRS)

    Garmany, C. D.; Stencel, R. E.

    1992-01-01

    The literature on all OB associations was reviewed, and their IRAS point source content was studied, between galactic longitude 55 and 150 deg. Only one third of the 24 associations listed by Ruprecht et al. (1981) have been the subject of individual studies designed to identify the brightest stars. Distances to all of these were recomputed using the method of cluster fitting of the B main sequence stars, which makes it poossible to reexamine the absolute magnitude calibration of the O stars, as well as for the red supergiant candidate stars. Also examined was the composite HR diagram for these associations. Associations with the best defined main sequences, which also tend to contain very young clusters, referred to here as OB clusters, have extremely few evolved B and A or red supergiants. Associations with poorly defined main sequences and few OB clusters have many more evolved stars. They also show an effect in the upper HR diagram referred to as a ledge by Fitzpatrick and Garmany (1990) in similar data for the Large Magellanic Cloud. It is suggested that the differences in the associations are not just observational selection effects but represent real differences in age and formation history.

  17. Canard-body-tail missile test at angles of attack to 50 deg in the Ames 11-foot transonic wind tunnel

    NASA Technical Reports Server (NTRS)

    Allen, C. Q.; Schwind, R. G.; Malcolm, G. N.

    1978-01-01

    Blunted ogive cylinder missile models with a length-to-diameter ratio of 10.4 were tested at transonic speeds and large angles of attack in an 11 foot transonic wind tunnel. The configurations are: body, body with tail panels, body with canards, and body with canards and tails. Forces and moments from the entire model and each of the eight fins were measured over the pitch range of 20 deg to 50 deg, and roll angles of 0 deg to 45 deg and canard deflection angles between 0 deg and 15 deg. The Reynolds number ranged from 3.9 x 10 to the 6th power per meter. Large side forces and yawing moments were observed for some of the test cases involving a symmetric geometry.

  18. Estimation of Static Longitudinal Stability of Aircraft Configurations at High Mach Numbers and at Angles of Attack Between 0 deg and +/-180 deg

    NASA Technical Reports Server (NTRS)

    Dugan, Duane W.

    1959-01-01

    The possibility of obtaining useful estimates of the static longitudinal stability of aircraft flying at high supersonic Mach numbers at angles of attack between 0 and +/-180 deg is explored. Existing theories, empirical formulas, and graphical procedures are employed to estimate the normal-force and pitching-moment characteristics of an example airplane configuration consisting of an ogive-cylinder body, trapezoidal wing, and cruciform trapezoidal tail. Existing wind-tunnel data for this configuration at a Mach number of 6.86 provide an evaluation of the estimates up to an angle of attack of 35 deg. Evaluation at higher angles of attack is afforded by data obtained from wind-tunnel tests made with the same configuration at angles of attack between 30 and 150 deg at five Mach numbers between 2.5 and 3.55. Over the ranges of Mach numbers and angles of attack investigated, predictions of normal force and center-of-pressure locations for the configuration considered agree well with those obtained experimentally, particularly at the higher Mach numbers.

  19. Forced Rolling Oscillation of a 65 deg-Delta Wing in Transonic Vortex-Breakdown Flow

    NASA Technical Reports Server (NTRS)

    Menzies, Margaret A.; Kandil, Osama A.; Kandil, Hamdy A.

    1996-01-01

    Unsteady, transonic, vortex dominated flow over a 65 deg. sharp-edged, cropped-delta wing of zero thickness undergoing forced rolling oscillations is investigated computationally. The wing angle of attack is 20 deg. and the free stream Mach number and Reynolds number are 0.85 and 3.23 x 10(exp 6), respectively. The initial condition of the flow is characterized by a transverse terminating shock which induces vortex breakdown of the leading edge vortex cores. The computational investigation uses the time accurate solution of the laminar, unsteady, compressible, full Navier-Stokes equations with the implicit, upwind, Roe flux difference splitting, finite-volume scheme. While the maximum roll amplitude is kept constant at 4.0 deg., both Reynolds number and roll frequency are varied covering three cases of forced sinusoidal rolling. First, the Reynolds number is held at 3.23 x 10(exp 6) and the wing is forced to oscillate in roll around the axis of geometric symmetry at a reduced frequency of 2(pi). Second, the Reynolds number is reduced to 0.5 x 10(exp 6) to observe the effects of added viscosity on the vortex breakdown. Third, with the Reynolds number held at 0.5 x 10(exp 6), the roll frequency is reduced to 1(pi) to complete the study.

  20. Tabulated Pressure Data for a Series of Controls on a 40 Deg Sweptback Wing at Mach Numbers of 1.61 and 2.01

    NASA Technical Reports Server (NTRS)

    Lord, D. R.

    1957-01-01

    An investigation has been made at Mach numbers of 1.61 and 2.01 and Reynolds numbers of 1.7 x l0(exp 6) and 3.6 x l0(exp 6) to determine the pressure distributions over a swept wing with a series of 14 control configurations. The wing had 40 deg of sweep of the quarter-chord line, an aspect ratio of 3.1, and a taper ratio of 0.4. Measurements were made at angles of attack from 0 deg to +/- 15 deg for control deflections from -60 deg to 60 deg. This report contains tabulated pressure data for the complete range of test conditions.

  1. 2 deg spacing - Its impact on domestic satellite systems

    NASA Astrophysics Data System (ADS)

    Braun, W. H.

    1981-11-01

    The provision of greater domestic satellite systems capacity through a reduction of satellite angular separation from 4.0 to 2.0 deg, making more orbital positions available, is considered from the standpoint of uplink and downlink interference mechanisms. It is determined that, while a 2.0-deg spacing requires improvements in antenna technology which may render existing facilities obsolete, and whose costs remain to be balanced against the economic gains represented by the greater number of orbital slots, an intermediate, 3.0-deg spacing for C-band domestic satellites presents few technical impediments. Most traffic modes will experience only modest reduction in system margins at this spacing, and no significant performance degradations. The standardization of spacecraft frequency and polarization plans, along with off-axis polarization discrimination in existing earth station antennas, offer means of recovering lost system margins.

  2. Temperature dependence, 0 to 40 deg. C, of the mineralogy of Portland cement paste in the presence of calcium carbonate

    SciTech Connect

    Matschei, Thomas; Glasser, Fredrik P.

    2010-05-15

    Thermodynamic calculations disclose that significant changes of the AFm and AFt phases and amount of Ca(OH){sub 2} occur between 0 and 40 deg. C; the changes are affected by added calcite. Hydrogarnet, C{sub 3}AH{sub 6}, is destabilised at low carbonate contents and/or low temperatures < 8 deg. C and is unlikely to form in calcite-saturated Portland cement compositions cured at < 40 deg. C. The AFm phase actually consists of several structurally-related compositions which form incomplete solid solutions. The AFt phase is close to its ideal stoichiometry at 25 deg. C but at low temperatures, < 20 deg. C, extensive solid solutions occur with CO{sub 3}-ettringite. A nomenclature scheme is proposed and AFm-AFt phase relations are presented in isothermal sections at 5, 25 and 40 deg. C. The AFt and AFm phase relations are depicted in terms of competition between OH, CO{sub 3} and SO{sub 4} for anion sites. Diagrams are presented showing how changing temperatures affect the volume of the solid phases with implications for space filling by the paste. Specimen calculations are related to regimes likely to occur in commercial cements and suggestions are made for testing thermal impacts on cement properties by defining four regimes. It is concluded that calculation provides a rapid and effective tool for exploring the response of cement systems to changing composition and temperature and to optimise cement performance.

  3. The East Pacific Rise 8\\deg to 11\\deg N Integrated Studies Site (ISS); Update and Opportunities

    NASA Astrophysics Data System (ADS)

    Carbotte, S.; Haymon, R.; Holland, M.; von Damm, K.

    2003-12-01

    The 8\\deg to 11\\deg N segment of the East Pacific Rise (EPR) represents a dynamic, fast-spreading type of mid-ocean ridge selected for focused interdisciplinary study within the Ridge 2000 program. Diverse fast spreading environments are encompassed by the site including a hierarchy of axial segments and discontinuities. The site "bull's- eye" is at 9\\deg49' to 9\\deg51' N where numerous high temperature vents and diffuse flow communities have been mapped and monitored over the past 14 years. Concentric circles around the bull's eye encompass ridge segments at a range of scales, from the first-order segment bounded by the Siquieros and Clipperton transform faults to the fourth-order segment which includes the extent of the 1991 and 1992 volcanic eruptions. Five-year goals for the site include a working model of mantle flow and melt supply; detailed imaging of subseafloor structures and relationships to vent communities and chemistry; quantitative data about microbes and macrofauna and linkages with fluid flow, tectonics, and magmatism; quantification of the heat/chemical flux into the water column; and linkages and temporal variation in geological, chemical, and biological parameters. Field programs in 2002 collected data for calculations of primary and secondary productivity at different vent communities, with a focus on tube worms and bivalves; searched for hydrothermal signals from an earlier earthquake swarm; and continued time-series fluid sampling at all 9\\deg10' to 9\\deg51'N high-temperature vents. 2003 cruises will continue geophysical/volcanological studies and deploy an array of in situ chemical sensors for use in monitoring vent fluids. Programs scheduled to begin in 2004 include three-dimensional multi-channel seismic and magnetotelluric studies of subsurface structure at the site "Bull's eye", initiation of monitoring studies of seismicity, fluid temperature and chemistry, and vent fauna. An overview of on-going and upcoming studies at the site

  4. Heavy metals in the near-surface aerosol over the Atlantic Ocean from 60 deg South to 54 deg North

    NASA Astrophysics Data System (ADS)

    Voelkening, Joachim; Heumann, Klaus G.

    1990-11-01

    Results are presented on determinations (by isotope dilution mass spectrometry) of the particulate heavy metal concentrations of Cr, Fe, Ni, Cu, Zn, Cd, Tl, and Pb in the atmospheric samples collected during the cruise of the Polarstern research ship over the Atlantic Ocean from 60 deg S to 54 deg N. The lowest abundance of all heavy metals was exhibited in the remote areas of the South Atlantic, whereas the highest abundances were detected around the English Channel. The data clearly identify the anthropogenic influence, e.g., over the South Atlantic near the La Plata area, the area around the English Channel, and over the North Sea.

  5. Survey of the galactic disk from 1 = -150 deg to 1 = 82 deg in the submillimeter range

    NASA Technical Reports Server (NTRS)

    Caux, Emmanuel; Serra, Guy

    1987-01-01

    The first almost complete survey of the galactic disk from 1 = -150 deg to 1 = 82 deg in the submillimeter range (effective wavelength = 380 microns), performed with the AGLAE balloon-borne instrument modified to include a submillimeter channel, is reported. The instrumentation and observational procedures are described, as are the signal processing and calibration. The results are presented as a profile of the submillimeter brightness of the galactic disk displayed as a function of the galactic longitude. This profile exhibits diffuse emission all along the disk with bright peaks associated with resolved sources. The averaged galactic spectrum is in agreement with a temperature distribution of the interstellar cold dust.

  6. Band offset engineering of 2DEG oxide systems on Si

    NASA Astrophysics Data System (ADS)

    Jin, Eric; Kornblum, Lior; Kumah, Divine; Zou, Ke; Broadbridge, Christine; Ngai, Joseph; Ahn, Charles; Walker, Fred

    2015-03-01

    The discovery of 2-dimensional electron gases (2DEGs) at perovskite oxide interfaces has sparked much interest in recent years due to their large carrier densities when compared with semiconductor heterostructures. For device applications, these oxide systems are plagued by low room temperature electrical mobilities. We present an approach to combine the high carrier density of 2DEG oxides with a higher mobility medium in order to realize the combined benefits of higher mobility and carrier density. We grow epitaxial films of the interfacial oxide system LaTiO3/SrTiO3 (LTO/STO) on silicon by molecular beam epitaxy. Magnetotransport measurements show that the sheet carrier densities of the heterostructures scale with the number of LTO/STO interfaces, consistent with the presence of a 2DEG at each interface. Sheet carrier densities of 8.9 x 1014 cm-2 per interface are measured. Band offsets between the STO and Si are obtained, showing that the conduction band edge of the STO is close in energy to that of silicon, but in a direction that hinders carrier transfer to the silicon substrate. Through modification of the STO/Si interface, we suggest an approach to raise the band offset in order to move the 2DEG from the oxide into the silicon.

  7. Spedali Degli Innocenti, the Foundling Hospital in Florence, Italy.

    PubMed

    Summers, Bruce

    2016-06-01

    The author reflects on a visit to the Ospedale Degli Innocenti, the former Renaissance foundling hospital in Florence, having escaped from an international clinical conference. He considers the symbolism of the architecture and artwork in relation to its function as a sanctuary for abandoned children. PMID:26612547

  8. Stratospheric Ozone Climatology from Lidar Measurements at Table Mountain (34.0 deg N, 117.7 deg W) and Mauna Loa (19.5 deg N, 155.6 deg W)

    NASA Technical Reports Server (NTRS)

    Leblanc, T.; McDermid, I. S.

    2000-01-01

    Using more than 1600 nighttime profiles obtained by the JPL differential absorption lidars (DIAL) located at Table Mountain Facility (TMF, 34.4 N) and Mauna Loa Observatory (MLO, 19.5 N) is presented in this paper. These two systems have been providing high-resolution vertical profiles of ozone number density between 15-50 km, several nights a week since 1989 (TMF) and 1993 (MLO). The climatology presented here is typical of early night ozone values with only a small influence of the Pinatubo aerosols and the 11-year solar cycle. The observed seasonal and vertical structure of the ozone concentration at TMF is consistent with that typical of mid- to subtropical latitudes. A clear annual cycle in opposite phase below and above the ozone concentration peak is observed. The observed winter maximum below the ozone peak is associated with a maximum day-to-day variability, typical of a dynamically driven lower stratosphere. The maximum concentration observed in summer above the ozone peak emphasizes the more dominant role of photochemistry. Unlike TMF, the ozone concentration observed at MLO tends to be higher during the summer months and lower during the winter months throughout the entire stratospheric ozone layer. Only a weak signature of the extra-tropical latitudes is observed near 19-20 km, with a secondary maximum in late winter. The only large variability observed at MLO is associated with the natural variability of the tropical tropopause.

  9. Growth of Listeria monocytogenes on Queso Fresco during storage at 4 deg and 10 deg C

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Queso Fresco (QF) is a white, high-moisture, slightly-crumbly, and salty Hispanic-style cheese that has been implicated in several outbreaks of listeriosis. The relatively high pH (>6.0) and high moisture content (>50%) coupled with the labor intensive practices of QF production may lead to contamin...

  10. Long-term creep of Hanford concrete at 250 deg F and 350 deg F

    NASA Astrophysics Data System (ADS)

    Gillen, M.

    1980-10-01

    Test results described cover the creep behavior of Hanford concretes at elevated temperatures. Two each of 6 by 12 in. concrete cylinders were subjected to static compressive loads of 500 psi at 350 F and 1500 psi at 250 F and 350 F. Test cylinders were cast with materials and mix designs similar to those used in Hanford concrete structures. Effects of load and temperature on deformation of Hanford concrete are discussed. Increased static load reduced the amount of thermal strain when cylinders were heated above ambient. At 350 F, the magnitude of creep strain of cylinders increased with increased static load. At a test load of 1500 psi, magnitude of creep strain increased with increased temperature. Creep data were satisfactorily modeled with an expression of the form creep strain = A log10 (t) + B, where creep strain is in millionths, and t is time at test temperature, in days. Values for the coefficient, A, varied from 255.6 to 286.9. Magnitude of the constant B, ranged from 182.1 to 718.6.

  11. Heading down early on? Start of subduction on Earth

    NASA Astrophysics Data System (ADS)

    Turner, Simon; Rushmer, Tracy; Reagan, Mark; Moyen, Jean-Francois

    2014-05-01

    How the Earth's earliest crust was formed and when present day plate tectonics (i.e. subduction) and life commenced, remain fundamental questions in Earth sciences. Whereas the bulk composition of the crust is similar to that of rocks generated in subduction settings, it does not necessarily follow that melting and crust formation require subduction. Indeed, many workers suggest that subduction may have only commenced towards the end of the Archean or later. Here we observe that both the stratigraphy and geochemistry of rocks found in Quebec, that have been variously argued to be 4.4 or 3.8 Ga in age, closely match those from the modern day Izu-Bonin-Mariana fore-arc. We suggest this geochemical stratigraphy might provide a more robust test of ancient tectonic setting than individual chemical or isotopic signatures in rocks or detrital minerals. If correct, the match suggests that at least some form of subduction may have been operating as early as the Hadean or Eoarchean. This could have provided an ideal location for the development of first life.

  12. Hydrothermal crystallization of Na{sub 2}Ti{sub 6}O{sub 13}, Na{sub 2}Ti{sub 3}O{sub 7}, and Na{sub 16}Ti{sub 10}O{sub 28} in the NaOH-TiO{sub 2}-H{sub 2}O system at a temperature of 500 deg. C and a pressure of 0.1 GPa: The structural mechanism of self-assembly of titanates from suprapolyhedral clusters

    SciTech Connect

    Hyushin, G. D.

    2006-07-15

    An increase in the NaOH concentration in the NaOH-TiO{sub 2} (rutile)-H{sub 2}O system at a temperature of 500 deg. C and a pressure of 0.1 GPa leads to the crystallization R-TiO{sub 2} + Na{sub 2}Ti{sub 6}O{sub 13} {sup {yields}} Na{sub 2}Ti{sub 3}O{sub 7} {sup {yields}} Na{sub 16}Ti{sub 10}O{sub 28}. Crystals of the Na{sub 2}Ti{sub 6}O{sub 13} titanate (space group C2/m) have the three-dimensional framework structure Ti{sub 6}O{sub 13}. The structure of the Na{sub 2}Ti{sub 3}O{sub 7} titanate (space group P2{sub 1}/m) contains the two-dimensional layers Ti{sub 3}O{sub 7}. The structure of the Na{sub 16}Ti{sub 10}O{sub 28} titanate (space group P-1) is composed of the isolated ten-polyhedron cluster precursors Ti{sub 10}O{sub 28}. In all the structures, the titanium atoms have an octahedral coordination (MTiO{sub 6}). The matrix self-assembly of the Na{sub 2}Ti{sub 6}O{sub 13} and Na{sub 2}Ti{sub 3}O{sub 7} (Na{sub 4}Ti{sub 6}O{sub 14}) crystal structures from Na{sub 4}M{sub 12} invariant precursors is modeled. These precursors are clusters consisting of twelve M polyhedra linked through the edges. It is demonstrated that the structurally rigid precursors Na{sub 4}M{sub 12} control all processes of the subsequent evolution of the crystal-forming titanate clusters. The specific features of the self-assembly of the Na{sub 2}Ti{sub 3}O{sub 7} structure that result from the additional incorporation of twice the number of sodium atoms into the composition of the high-level clusters are considered.

  13. Compressibility and Leading-Edge Bluntness Effects for a 65 Deg Delta Wing

    NASA Technical Reports Server (NTRS)

    Luckring, J. M.

    2004-01-01

    A 65 deg. delta wing has been tested in the National Transonic Facility (NTF) at mean aerodynamic chord Reynolds numbers from 6 million to 120 million at subsonic and transonic speeds. The configuration incorporated a systematic variation of the leading edge bluntness. The analysis for this paper is focused on the compressibility and bluntness effects primarily at a Reynolds number of 6 million from this data set. Emphasis is placed upon on the onset and progression of leading-edge vortex separation, and compressibility is shown to promote this separation. Comparisons with recent publications show that compressibility and Reynolds number have opposite effects on blunt leading edge vortex separation

  14. STEREO SECCHI COR1-A/B Intercalibration at 180 deg Separation

    NASA Technical Reports Server (NTRS)

    Thompson, W. T.; Davila, J. M.; St.Cyr, O. C.; Reginald, N. L.

    2011-01-01

    The twin Solar Terrestrial Relations Observatory (STEREO) spacecraft reached a separation angle of 180 deg on 6 February 2011. This provided a unique opportunity to test the intercalibration between the Sun-Earth Connection Coronal and Heliospheric Investigation (SECCHI) telescopes on both spacecraft for areas above the limb. So long as the corona is optically thin, at 180 deg separation each spacecraft sees the same corona from opposite directions. Thus, the data should appear as mirror images of each other. We report here on the results of the comparison of the images taken by the inner coronagraph (COR1) on the STEREO-Ahead and -Behind spacecraft in the hours when the separation was close to 180 deg. We find that the intensity values seen by the two telescopes agree with each other to a high degree of accuracy. This validates both the radiometric intercalibration between the COR1 telescopes, and the method used to remove instrumental background from the images. The relative error between COR1-A and COR1-B is found to be less than 10-9 B/B over most of the field-of-view, growing to a few 10-9 B/B for the brighter pixels near the edge of the occulter. The primary source of error is the background determination. We also report on the analysis of star observations which show that the absolute radiometric calibration of either COR1 telescope has not changed significantly since launch.

  15. Rotary balance data for a typical single-engine general aviation design for an angle-of-attack range of 8 deg to 90 deg. 2: Low-wing model B

    NASA Technical Reports Server (NTRS)

    Bihrle, W., Jr.; Hultberg, R. S.

    1979-01-01

    Aerodynamic characteristics obtained in a rotational flow environment utilizing a rotary balance located in the spin tunnel are presented in plotted form for a 1/6.5 scale, single engine, low wing, general aviation airplane model. The configurations tested included the basic airplane, various wing leading-edge devices, tail designs, and rudder control settings as well as airplane components. Data are presented without analysis for an angle-of-attack range of 8 deg to 90 deg and clockwise and counter-clockwise rotations covering an (omega)(b)/2V range from 0 to 0.85.

  16. Rotary balance data for a typical single-engine general aviation design for an angle-of-attack range of 8 deg to 90 deg. 2: High-wing model C

    NASA Technical Reports Server (NTRS)

    Hultberg, R. S.; Chu, J.

    1980-01-01

    Aerodynamic characteristics obtained in a helical flow environment utilizing a rotary balance located in the Langley spin g tunnel are presented in plotted form for a 1/6 scale, single engine, high wing, general aviation model. The configurations tested included the basic airplane and control deflections, wing leading edge devices, tail designs, and airplane components. Data are presented without analysis for an angle of attack range of 8 deg to 90 deg and clockwise and counter clockwise rotations covering a spin coefficient range from 0 to 0.9.

  17. Rotary balance data for a typical single-engine general aviation design for an angle of attack range of 8 deg to 90 deg. 1: Low wing model C. [wind tunnel tests

    NASA Technical Reports Server (NTRS)

    Mulcay, W. J.; Rose, R. A.

    1980-01-01

    Aerodynamic characteristics obtained in a helical flow environment utilizing a rotary balance located in the Langley spin tunnel are presented in plotted form for a 1/6 scale, single engine, low wing, general aviation model (model C). The configurations tested included the basic airplane and control deflections, wing leading edge and fuselage modification devices, tail designs and airplane components. Data are presented without analysis for an angle of attack range of 8 deg to 90 deg and clockwise and counter clockwise rotations covering an omega b/2v range from 0 to .9.

  18. Rotary balance data for a typical single-engine general aviation design for an angle-of-attack range of 8 deg to 90 deg. 1: Influence of airplane components for model D. [Langley spin tunnel tests

    NASA Technical Reports Server (NTRS)

    Ralston, J.

    1983-01-01

    The influence of airplane components, as well as wing location and tail length, on the rotational flow aerodynamics is discussed for a 1/6 scale general aviation airplane model. The airplane was tested in a built-up fashion (i.e., body, body-wing, body-wing-vertical, etc.) in the presence of two wing locations and two body lengths. Data were measured, using a rotary balance, over an angle-of-attack range of 8 deg to 90 deg, and for clockwise and counter-clockwise rotations covering an omega b/2V range of 0 to 0.9.

  19. Insights into the Cyanobacterial Deg/HtrA Proteases

    PubMed Central

    Cheregi, Otilia; Wagner, Raik; Funk, Christiane

    2016-01-01

    Proteins are the main machinery for all living processes in a cell; they provide structural elements, regulate biochemical reactions as enzymes, and are the interface to the outside as receptors and transporters. Like any other machinery proteins have to be assembled correctly and need maintenance after damage, e.g., caused by changes in environmental conditions, genetic mutations, and limitations in the availability of cofactors. Proteases and chaperones help in repair, assembly, and folding of damaged and misfolded protein complexes cost-effective, with low energy investment compared with neo-synthesis. Despite their importance for viability, the specific biological role of most proteases in vivo is largely unknown. Deg/HtrA proteases, a family of serine-type ATP-independent proteases, have been shown in higher plants to be involved in the degradation of the Photosystem II reaction center protein D1. The objective of this review is to highlight the structure and function of their cyanobacterial orthologs. Homology modeling was used to find specific features of the SynDeg/HtrA proteases of Synechocystis sp. PCC 6803. Based on the available data concerning their location and their physiological substrates we conclude that these Deg proteases not only have important housekeeping and chaperone functions within the cell, but also are needed for remodeling the cell exterior. PMID:27252714

  20. Spin Related Transport in Rashba 2DEG Systems

    NASA Astrophysics Data System (ADS)

    Nitta, Junsaku

    Transport in mesoscopic conductors is determined not only by orbital motion of carriers but also by quantum interference effect. However, it is well known that the quantum interference such as weak localization is much modified in the presence of spin-orbit interaction (SOI), leading to weak anti-localization. We discuss the origin of the Rashba SOI and spin related mesoscopic transport in InGaAs based two dimensional electron gases (2DEG) affected by the Rashba SOI. It is experimentally shown that the strength of the Rashba SOI in InGaAs 2DEG systems can be controlled by the gate voltage.1 The spin dynamics in solid systems is commonly determined by the competition between Zeeman effect and SOI. The spin relaxation time and dephasing time are studied from weak anti-localization analysis as a function of the relative strength of the Zeeman energy (EZ) and the Rashba SOI energy (ESOI). The (EZ) was introduced by applying magnetic field parallel to the 2DEG plane. This in-pane magnetic field does not affect the orbital motion of electrons. The spin relaxation time increases with the Zeeman energy. The dephasing time associated with the spin-induced time reversal symmetry (TRS) breaking saturates when EZ becomes comparable to ESOI. Moreover, we show that the spin-induced TRS breaking mechanism is a universal function of the ratio EZ/ESOI within the experimental accuracy.2 Note from Publisher: This article contains the abstract only.

  1. Evaluation of candidate stirling engine heater tube alloys at 820 deg and 860 deg C

    NASA Technical Reports Server (NTRS)

    Misencik, J. A.

    1982-01-01

    Seven commercial alloys were evaluated in Stirling simulator materials rigs. Five iron base alloys (N-155, A-286, Incoloy 800, 19-9DL, and 316 stainless steel), one nickel base alloy (Inconel 718), and one cobalt base alloy (HS-188) were tested in the form of thin wall tubing in a diesel fuel fired test rig. Tubes filled with hydrogen or helium at gas pressure of 21.6 MPa and temperatures of 820 and 860 C were endurance tested for 1000 and 535 hours, respectively. Results showed that under these conditions hydrogen permeated rapidly through the tube walls, thus requiring refilling during each five hour cycle. Helium was readily contained, exhibiting no measurable loss by permeation. Helium filled tubes tested at 860 C all exhibited creep-rupture failures within the 535 hour endurance test. Subsequent tensile test evaluation after removal from the rig indicated reduced room temperature ductility for some hydrogen-filled tubes compared to helium-filled tubes, suggesting possible hydrogen embrittlement in these alloys.

  2. Transonic Reynolds Number and Leading-Edge Bluntness Effects on a 65 deg Delta Wing

    NASA Technical Reports Server (NTRS)

    Luckring, J. M.

    2003-01-01

    A 65 deg delta wing has been tested in the National Transonic Facility (NTF) at mean aerodynamic chord Reynolds numbers from 6 million to 120 million at subsonic and transonic speeds. The configuration incorporated a systematic variation of the leading edge bluntness. The analysis for this paper is focused on the Reynolds number and bluntness effects at transonic speeds (M=0.85) from this data set. The results show significant effects of both these parameters on the onset and progression of leading-edge vortex separation.

  3. Transonic Reynolds Number and Leading-Edge Bluntness Effects on a 65 deg Delta Wing

    NASA Technical Reports Server (NTRS)

    Luckring, J. M.

    2003-01-01

    A 65 deg delta wing has been tested in the National Transonic Facility (NTF) at mean aerodynamic chord Reynolds numbers from 6 million to 120 million at subsonic and transonic speeds. The configuration incorporated a systematic variation of the leading edge bluntness. The analysis for this paper is focused on the Reynolds number and bluntness effects at transonic speeds (M = 0.85) from this data set. The results show significant effects of both these parameters on the onset and progression of leading- edge vortex separation.

  4. Reynolds Number and Leading-Edge Bluntness Effects on a 65 Deg Delta Wing

    NASA Technical Reports Server (NTRS)

    Luckring, J. M.

    2002-01-01

    A 65 deg delta wing has been tested in the National Transonic Facility (NTF) at mean aerodynamic chord Reynolds numbers from 6 million to 120 million at subsonic and transonic speeds. The configuration incorporated systematic variation of the leading edge bluntness. The analysis for this paper is focused on the Reynolds number and bluntness effects at subsonic speeds (M = 0.4) from this data set. The results show significant effects of both these parameters on the onset and progression of leading-edge vortex separation.

  5. Technical Note: Using DEG-CPCs at upper tropospheric temperatures

    NASA Astrophysics Data System (ADS)

    Wimmer, D.; Lehtipalo, K.; Nieminen, T.; Duplissy, J.; Ehrhart, S.; Almeida, J.; Rondo, L.; Franchin, A.; Kreissl, F.; Bianchi, F.; Manninen, H. E.; Kulmala, M.; Curtius, J.; Petäjä, T.

    2015-07-01

    Over the last few years, several condensation particle counters (CPCs) capable of measuring in the sub-3 nm size range have been developed. Here we study the performance of CPCs based on diethylene glycol (DEG) at different temperatures during Cosmics Leaving OUtdoor Droplets (CLOUD) measurements at CERN. The data shown here are the first set of verification measurements for sub-3 nm CPCs under upper tropospheric temperatures using atmospherically relevant aerosol particles. To put the results in perspective we calibrated the DEG-CPC at room temperature, resulting in a cut-off diameter of 1.4 nm. All diameters refer to mobility equivalent diameters in this paper. At upper tropospheric temperatures ranging from 246.15 K to 207.15 K, we found cut-off sizes relative to a particle size magnifier in the range of 2.5 to 2.8 nm. Due to low number concentration after size classification, the cut-off diameters have a high uncertainty (±0.3 nm) associated with them. Operating two laminar flow DEG-CPCs with different cut-off sizes together with other aerosol instruments, we looked at the growth rates of aerosol population in the CLOUD chamber for particles smaller than 10 nm at different temperatures. A more consistent picture emerged when we normalized the growth rates to a fixed gas-phase sulfuric acid concentration. All of the instruments detected larger growth rates at lower temperatures, and the observed growth rates decreased as a function of temperature, showing a similar trend for all instruments. The theoretical calculations had a similar but much smaller temperature dependency.

  6. Low-speed aerodynamic characteristics of a 42 deg swept high-wing model having a double-slotted flap system and a supercritical airfoil

    NASA Technical Reports Server (NTRS)

    Fournier, P. G.; Goodson, K. W.

    1974-01-01

    A low-speed investigation was conducted over an angle-of-attack range from about -4 deg to 20 deg in the Langley V/STOL tunnel to determine the effects of a double-slotted flap, high-lift system on the aerodynamic characteristics of a 42 deg swept high-wing model having a supercritical airfoil. The wing had an aspect ratio of 6.78 and a taper ratio of 0.36; the double-slotted flap consisted of a 35-percent-chord flap with a 15-percent-chord vane. The model was tested with a 15-percent-chord leading-edge slat.

  7. Interpretation of the Minkowski bands in Grw + 70 deg 8247.

    NASA Technical Reports Server (NTRS)

    Angel, J. R. P.

    1972-01-01

    Demonstration on the basis of the spectral structure of circular polarization in Grw + 70 deg 8247, that the absorption bands are at least in part molecular in origin. The spectrum of molecular helium has strong bands coincident with several of the Minkowski bands and, in particular, at high temperature shows a strong band head at about 4125 A. Helium molecules could be formed in sufficient density to give the absorption features in the star if it has a pure helium atmosphere. The Zeeman effect in molecular helium can explain in general the observed spectral features in the polarization and also may be responsible for the continuum polarization.

  8. 360-deg profilometry: new techniques for display and acquisition

    NASA Astrophysics Data System (ADS)

    Asundi, Anand K.; Chan, Chi-Shing; Sajan, M. R.

    1994-08-01

    Two optical methods are proposed for shape measurement and defect detection of curved surfaces in the form of a complete 350-deg profile of the object. The first one is the standard structured light approach. Display of the resulting data is the emphasis of this section. The second approach uses modulated structured light with a scanning digital camera for faster and simpler data acquisition. Quantitative processing is done off-line while real-time moire produces enhanced display of the defects for qualitative analysis.

  9. The occultation of AG+29 deg 398 by 98 Minerva

    NASA Technical Reports Server (NTRS)

    Millis, R. L.; Wasserman, L. H.; Bowell, E.; Franz, O. G.; Nye, R.; Osborn, W.; Klemola, A.

    1984-01-01

    On 22 Nov. 1982, the asteroid 93 Minerva occulted AG-29 deg 398 (= SAO 76O17A), a seventh magnitude star of AO spectral type. The data were best fitted by a circular limb profile having a diameter of 170.8 + or - 1.4 km, a value that agrees well with the published radiometric diameter for this asteroid. However, evidence of significant departure from a spherical shape is found in the occultation observations and in photometric measurements of Minerva. Additional observations are required to specify difinitively the three dimensional figure of Minerva.

  10. Mutation of a degS homologue in Enterobacter cloacae decreases colonization and biological control of damping-off on cucumber.

    PubMed

    Roberts, Daniel P; Lohrke, Scott M; McKenna, Laurie; Lakshman, Dilip K; Kong, Hyesuk; Lydon, John

    2011-02-01

    We have been using mutagenesis to determine how biocontrol bacteria such as Enterobacter cloacae 501R3 deal with complex nutritional environments found in association with plants. E. cloacae C10, a mutant of 501R3 with a transposon insertion in degS, was diminished in growth on synthetic cucumber root exudate (SRE), colonization of cucumber seed and roots, and control of damping-off of cucumber caused by Pythium ultimum. DegS, a periplasmic serine protease in the closely related bacterium Escherichia coli K12, is required for the RpoE-mediated stress response. C10 containing wild-type degS from 501R3 or from E. coli K12 on pBeloBAC11 was significantly increased in growth on SRE, colonization of cucumber roots, and control of P. ultimum relative to C10 containing pBeloBAC11 alone. C10 and 501R3 were similar in sensitivity to acidic conditions, plant-derived phenolic compounds, oxidative stress caused by hydrogen peroxide, dessication, and high osmoticum; stress conditions potentially associated with plants. This study demonstrates a role for degS in the spermosphere and rhizosphere during colonization and disease control by Enterobacter cloacae. This study implicates, for the first time, the involvement of DegS and, by extension, the RpoE-mediated stress response, in reducing stress on E. cloacae resulting from the complex nutritional environments in the spermosphere and rhizosphere. PMID:20942652

  11. Water-Film Cooling of an 80 deg Total-Angle Cone at a Mach Number of 2 for Airstream Total Temperatures up to 3,000 deg R

    NASA Technical Reports Server (NTRS)

    Carter, Howard S.

    1959-01-01

    Film-cooling tests, with water as the coolant, were made on an 80 deg total-angle cone in a Mach number 2 free jet at sea-level pressure. The tests were made at free-stream total temperatures from 1,500 deg R to 3,000 deg R and at free-stream Reynolds numbers per foot from 8 x 10(exp 6) to 3 x 10(exp 6). The tests showed that the downstream end of the model became very hot if the coolant rate was too small to cover the complete model with a water film. This water film was fairly symmetrical when the model was at zero angle of attack but was very asymmetrical when the model was at an angle of attack of 5 deg. A comparison with results of a previous transpiration-cooling test showed that, with water as the coolant, transpiration cooling was at least 2.5 times as efficient as the film cooling of the present tests.

  12. Comprehensive study on critical role of surface oxygen vacancies for 2DEG formation and annihilation in LaAlO3/SrTiO3 heterointerfaces

    NASA Astrophysics Data System (ADS)

    Moon, Seon Young; Moon, Cheon Woo; Chang, Hye Jung; Kim, Taemin; Kang, Chong-Yun; Choi, Heon-Jin; Kim, Jin-Sang; Baek, Seung-Hyub; Jang, Ho Won

    2016-03-01

    Here we report comprehensive study of 2DEG at a-LAO/STO interfaces in comparison with 2DEG at crystalline LaAlO3 (c-LAO)/STO interfaces. We observe that the oxygen deficient environment during the deposition of LAO overlayer is essentially required to create 2DEG at LAO/STO interface regardless of growth temperature from 25°C to 700°C, indicating that the oxygen-poor condition in the system is more important than the crystallinity of LAO layer. The critical thickness (2.6 nm) of 2DEG formation at a-LAO/STO heterostructure is thicker than (1.6 nm) that at c-LAO/STO. Upon ex-situ annealing at 300°C under 300 mTorr of oxygen pressure, 2DEG at a-LAO/STO interface is annihilated, while that in c-LAO/STO interface is still maintained. With combing these findings and scanning transmission electron microscope (STEM) analysis, we suggest that oxygen vacancies at the LAO surface is attributed to the origin of 2DEG formation at the LAO/STO and the crystallinity of the LAO overlayer plays a critical role in the annihilation of 2DEG at a-LAO/STO interface rather than in the formation of 2DEG. This work provides a framework to understand the importance of prohibiting the LAO surface from being oxidized for achieving thermally stable 2DEG at a-LAO/STO interface. [Figure not available: see fulltext.

  13. Multi-frequency polarimetry of the Galactic radio background around 350 MHz. I. A region in Auriga around l = 161 deg, b = 16 deg

    NASA Astrophysics Data System (ADS)

    Haverkorn, M.; Katgert, P.; de Bruyn, A. G.

    2003-06-01

    With the Westerbork Synthesis Radio Telescope (WSRT), multi-frequency polarimetric images were taken of the diffuse radio synchrotron background in a ~ 5 deg times 7 deg region centered on (l,b) = (161 deg ,16 deg ) in the constellation of Auriga. The observations were done simultaneously in 5 frequency bands, from 341 MHz to 375 MHz, and have a resolution of ~ 5.0arcminx5 .0arcmin cosec delta . The polarized intensity P and polarization angle phi show ubiquitous structure on arcminute and degree scales, with polarized brightness temperatures up to about 13 K. On the other hand, no structure at all is observed in total intensity I to an rms limit of 1.3 K, indicating that the structure in the polarized radiation must be due to Faraday rotation and depolarization mostly in the warm component of the nearby Galactic interstellar medium (ISM). Different depolarization processes create structure in polarized intensity P. Beam depolarization creates ``depolarization canals'' of one beam wide, while depth depolarization is thought to be responsible for creating most of the structure on scales larger than a beam width. Rotation measures (RM) can be reliably determined, and are in the range -17 <~ RM <~ 10 rad m-2 with a non-zero average RM0 ~ -3.4 rad m-2. The distribution of RMs on the sky shows both abrupt changes on the scales of the beam and a gradient in the direction of positive Galactic longitude of ~ 1 rad m-2 per degree. The gradient and average RM are consistent with a regular magnetic field of ~ 1 mu G which has a pitch angle of p = -14 deg. There are 13 extragalactic sources in the field for which RMs could be derived, and those have |RM| <~ 13 rad m-2, with an estimated intrinsic source contribution of ~ 3.6 rad m-2. The RMs of the extragalactic sources show a gradient that is about 3 times larger than the gradient in the RMs of the diffuse emission and that is approximately in Galactic latitude. This difference is ascribed to a vastly different effective

  14. Impingement of Droplets in 90 deg Elbows with Potential Flow

    NASA Technical Reports Server (NTRS)

    Hacker, Paul T.; Brun, Rinaldo J.; Boyd, Bemrose

    1953-01-01

    Trajectories were determined for droplets in air flowing through 90 deg elbows especially designed for two-dimensional potential motion with low pressure losses. The elbows were established by selecting as walls of each elbow two streamlines of the flow field produced by a complex potential function that establishes a two-dimensional flow around a 90 deg bend. An unlimited number of elbows with slightly different shapes can be established by selecting different pairs of streamlines as walls. The elbows produced by the complex potential function selected are suitable for use in aircraft air-intake ducts. The droplet impingement data derived from the trajectories are presented along with equations in such a manner that the collection efficiency, the area, the rate, and the distribution of droplet impingement can be determined for any elbow defined by any pair of streamlines within a portion of the flow field established by the complex potential function. Coordinates for some typical streamlines of the flow field and velocity components for several points along these streamlines are presented in tabular form.

  15. F-15 rotary balance data for an angle-of-attack range of 8 deg to 90 deg

    NASA Technical Reports Server (NTRS)

    Barnhart, B.

    1982-01-01

    Aerodynamic characteristics obtained in a rotational flow environment, utilizing a rotary balance are presented in plotted form for a 1/12 scale F-15 airplane model. The configurations tested included the buildup of airplane components and the basic airplane with various control deflections. Data are presented for all configurations without analysis for an angle of attack range of 8 to 90 deg, and clockwise and counterclockwise rotations covering an omega b/2V range from 0 to 0.4. Selected configurations are presented over an extended omega b/2V range from 0 to 0.9.

  16. Using the SUBcellular database for Arabidopsis proteins to localize the Deg protease family.

    PubMed

    Tanz, Sandra K; Castleden, Ian; Hooper, Cornelia M; Small, Ian; Millar, A Harvey

    2014-01-01

    Sub-functionalization during the expansion of gene families in eukaryotes has occurred in part through specific subcellular localization of different family members. To better understand this process in plants, compiled records of large-scale proteomic and fluorescent protein localization datasets can be explored and bioinformatic predictions for protein localization can be used to predict the gaps in experimental data. This process can be followed by targeted experiments to test predictions. The SUBA3 database is a free web-service at http://suba.plantenergy.uwa.edu.au that helps users to explore reported experimental data and predictions concerning proteins encoded by gene families and to define the experiments required to locate these homologous sets of proteins. Here we show how SUBA3 can be used to explore the subcellular location of the Deg protease family of ATP-independent serine endopeptidases (Deg1-Deg16). Combined data integration and new experiments refined location information for Deg1 and Deg9, confirmed Deg2, Deg5, and Deg8 in plastids and Deg 15 in peroxisomes and provide substantial experimental evidence for mitochondrial localized Deg proteases. Two of these, Deg3 and Deg10, additionally localized to the plastid, revealing novel dual-targeted Deg proteases in the plastid and the mitochondrion. SUBA3 is continually updated to ensure that researchers can use the latest published data when planning the experimental steps remaining to localize gene family functions. PMID:25161662

  17. Using the SUBcellular database for Arabidopsis proteins to localize the Deg protease family

    PubMed Central

    Tanz, Sandra K.; Castleden, Ian; Hooper, Cornelia M.; Small, Ian; Millar, A. Harvey

    2014-01-01

    Sub-functionalization during the expansion of gene families in eukaryotes has occurred in part through specific subcellular localization of different family members. To better understand this process in plants, compiled records of large-scale proteomic and fluorescent protein localization datasets can be explored and bioinformatic predictions for protein localization can be used to predict the gaps in experimental data. This process can be followed by targeted experiments to test predictions. The SUBA3 database is a free web-service at http://suba.plantenergy.uwa.edu.au that helps users to explore reported experimental data and predictions concerning proteins encoded by gene families and to define the experiments required to locate these homologous sets of proteins. Here we show how SUBA3 can be used to explore the subcellular location of the Deg protease family of ATP-independent serine endopeptidases (Deg1–Deg16). Combined data integration and new experiments refined location information for Deg1 and Deg9, confirmed Deg2, Deg5, and Deg8 in plastids and Deg 15 in peroxisomes and provide substantial experimental evidence for mitochondrial localized Deg proteases. Two of these, Deg3 and Deg10, additionally localized to the plastid, revealing novel dual-targeted Deg proteases in the plastid and the mitochondrion. SUBA3 is continually updated to ensure that researchers can use the latest published data when planning the experimental steps remaining to localize gene family functions. PMID:25161662

  18. Magnetometory Measurement of AlGaN/GaN 2DEG

    NASA Astrophysics Data System (ADS)

    Tsubaki, K.; Maeda, N.; Saitoh, T.; Kobayashi, N.

    2004-03-01

    AlGaN/GaN heterostructure devices have been attracting much attention because of their potential for high-performance microwave applications. Therefore, the electronic properties of a 2DEG in AlGaN/GaN heterostructures have recently been discussed. In this paper, we performed the magnetometory measurement of AlGaN/GaN 2DEG at low temperature. The AlGaN/GaN heterostructures were grown by low-pressure metal-organic chemical vapour phase epitaxy on (0001) SiC substrate using AlN buffers. The electron mobility and electron concentration at 4.2 K are 9,540 cm^2/Vs and 6.6 × 10^12 cm-2, respectively. When the temperature is lower than 4.5 K the hysteresis of magnetometric data is observed near zero magnetic field. At the temperature larger than 4.5 K, the hysteresis of magnetometric data disappears and the slope of magnetometric data with respect to magnetic field becomes lower as obeying Currie-Weiss law. In general the hysteresis and Currie-Weiss law behavior in magnetometric data imply the possibility of the ferromagnetism, but the conformation of the ferromagnetism of AlGaN/GaN heterostructure is still difficult and the detailed physical mechanism is still unclear.

  19. Circulation on the continental shelf between 87 deg W and 90 deg W with data appendix. Final report, volume 1

    SciTech Connect

    Eleuterius, C.K.; Criss, G.A.

    1994-08-01

    Knowledge of the circulation of waters over the continental shelf and slope between 87 deg W and 90 deg W longitude is essential for judicious management of the region`s living and mineral resources and related industrial activities. This region, an integral part of the Fertile Fisheries Crescent, has been in a state of on-going development by the oil and gas industry for over four decades. The increase in activities of all types on the shelf, e.g., offshore oil and gas, maritime commerce, and fisheries, with the inherent risks each imposes on the environment, underscores the need for better knowledge of the region`s hydrodynamics, biology, chemistry, and geology. Prior to planning and initiating any further physical oceanography studies which require taking additional measurements in this region, the authors believe it prudent to first extract whatever relevant information remains in existing data. This effort entailed the laborious recovery of oceanographic data at the Gulf Coast Research Laboratory, which was in a number of disparate forms and formats.

  20. Match broadband mixers to within 1-deg. phase

    NASA Astrophysics Data System (ADS)

    Duncan, David; Roach, Patrick

    1987-01-01

    Phase matching (determined by the absolute phase difference between the mixer devices) and tracking are important mixer specifications in missile guidance and threat detection systems. In this paper, a phase-matching technique, based on a requirement that the devices track one another in sets, is presented. The technique measures phase errors down to the 1-deg level with a test setup that is repeatable and easy to use. A typical test setup and the steps of the measuring procedure are described, and data plots showing the phase-tracking performance of a set of three mixers are shown. A block diagram of a typical setup and a flow chart for a phase-matching and incremental-tracking program are included.

  1. Dislocation Majorana zero modes in perovskite oxide 2DEG

    PubMed Central

    Chung, Suk Bum; Chan, Cheung; Yao, Hong

    2016-01-01

    Much of the current experimental efforts for detecting Majorana zero modes have been centered on probing the boundary of quantum wires with strong spin-orbit coupling. The same type of Majorana zero mode can also be realized at crystalline dislocations in 2D superconductors with the nontrivial weak topological indices. Unlike at an Abrikosov vortex, at such a dislocation, there is no other low-lying midgap state than the Majorana zero mode so that it avoids usual complications encountered in experimental detections such as scanning tunneling microscope (STM) measurements. We will show that, using the anisotropic dispersion of the t2g orbitals of Ti or Ta atoms, such a weak topological superconductivity can be realized when the surface two-dimensional electronic gas (2DEG) of SrTiO3 or KTaO3 becomes superconducting, which can occur through either intrinsic pairing or proximity to existing s-wave superconductors. PMID:27139319

  2. Dislocation Majorana zero modes in perovskite oxide 2DEG.

    PubMed

    Chung, Suk Bum; Chan, Cheung; Yao, Hong

    2016-01-01

    Much of the current experimental efforts for detecting Majorana zero modes have been centered on probing the boundary of quantum wires with strong spin-orbit coupling. The same type of Majorana zero mode can also be realized at crystalline dislocations in 2D superconductors with the nontrivial weak topological indices. Unlike at an Abrikosov vortex, at such a dislocation, there is no other low-lying midgap state than the Majorana zero mode so that it avoids usual complications encountered in experimental detections such as scanning tunneling microscope (STM) measurements. We will show that, using the anisotropic dispersion of the t2g orbitals of Ti or Ta atoms, such a weak topological superconductivity can be realized when the surface two-dimensional electronic gas (2DEG) of SrTiO3 or KTaO3 becomes superconducting, which can occur through either intrinsic pairing or proximity to existing s-wave superconductors. PMID:27139319

  3. Dislocation Majorana zero modes in perovskite oxide 2DEG

    NASA Astrophysics Data System (ADS)

    Chung, Suk Bum; Chan, Cheung; Yao, Hong

    2016-05-01

    Much of the current experimental efforts for detecting Majorana zero modes have been centered on probing the boundary of quantum wires with strong spin-orbit coupling. The same type of Majorana zero mode can also be realized at crystalline dislocations in 2D superconductors with the nontrivial weak topological indices. Unlike at an Abrikosov vortex, at such a dislocation, there is no other low-lying midgap state than the Majorana zero mode so that it avoids usual complications encountered in experimental detections such as scanning tunneling microscope (STM) measurements. We will show that, using the anisotropic dispersion of the t2g orbitals of Ti or Ta atoms, such a weak topological superconductivity can be realized when the surface two-dimensional electronic gas (2DEG) of SrTiO3 or KTaO3 becomes superconducting, which can occur through either intrinsic pairing or proximity to existing s-wave superconductors.

  4. Seasonal cycle in atmospheric HCl at 45 deg S

    NASA Technical Reports Server (NTRS)

    Matthews, W. Andrew; Jones, Nicholas B.; Johnston, Paul V.; Rinsland, Curtis P.; Goldman, Aaron

    1994-01-01

    High resolution Fourier transform infrared interferometric atmospheric solar absorption measurements have been performed at the National Institute for Water and Atmospheric Research Laboratory at Lauder, New Zealand on a routine basis since October 1989. This laboratory has been selected as the Mid-latitude Charter Site of the Network for the Detection of Stratospheric Change and is at a latitude of 45 deg S. Particular attention has been paid to the absorption by atmospheric hydrogen chloride at 2925.9 cm(exp -1) and in this paper the results of the seasonal cycle in CHl above Lauder will be presented. Because of the very clean troposphere at this site, the CHl column measured from the ground is essentially a stratospheric column measurement.

  5. Extending the R-2R lens to 360 deg

    NASA Astrophysics Data System (ADS)

    Clapp, R. E.

    1984-07-01

    The R-2R lens is a remarkable microwave device that provides perfect focusing, giving multiple simultaneous antenna beams from a circular or cylindrical array. However, the perfect focusing of the R-2R brings with it a serious limitation on angular coverage as a result of the angular doubling that enters when the array elements in the antenna are connected to the launcher elements on the lens periphery. A way has now been found to modify the R-2R concept so that a full circle of array elements can be mapped onto a full circle of beam ports. The new mapping makes use of hybrid junctions and either four or six physical lenses. The interconnections result in 360 deg of simultaneous antenna beams, each of which can be used both for transmission and for reception.

  6. 4-layer inductive grid FSS at 45 deg incidence

    NASA Astrophysics Data System (ADS)

    El-Morsy, M. A. A.; Parker, E. A.; Langley, R. J.

    1983-08-01

    Situations in which single-layer frequency-selective surfaces are required to produce reasonably close spacings between the transmission and reflection bands are considered. The choice of array element for linear polarization includes the Jerusalem cross, the concentric ring, and the double square. An alternative approach is to synthesize the required transmission curves using multiple layers of simpler structures, such as capacitive or inductive grids. The present investigation is concerned with results for two structures to illustrate some of the problems which can arise experimentally. Attention is given to an inductive mesh used in a 45 deg incidence diplexer, copolar losses in the case of a 4-layer inductive grid and 2-layer concentric rings, and linear crosspolar levels.

  7. Low-Speed Investigation of the Effects of Frequency and Amplitude of Oscillation in Sideslip on the Lateral Stability Derivatives of a 60 deg Delta Wing, a 45 deg Sweptback Wing and an Unswept Wing

    NASA Technical Reports Server (NTRS)

    Lichtenstein, Jacob H.; Williams, James L.

    1961-01-01

    A low-speed investigation has been conducted in the Langley stability tunnel to study the effects of frequency and amplitude of sideslipping motion on the lateral stability derivatives of a 60 deg. delta wing, a 45 deg. sweptback wing, and an unswept wing. The investigation was made for values of the reduced-frequency parameter of 0.066 and 0.218 and for a range of amplitudes from +/- 2 to +/- 6 deg. The results of the investigation indicated that increasing the frequency of the oscillation generally produced an appreciable change in magnitude of the lateral oscillatory stability derivatives in the higher angle-of-attack range. This effect was greatest for the 60 deg. delta wing and smallest for the unswept wing and generally resulted in a more linear variation of these derivatives with angle of attack. For the relatively high frequency at which the amplitude was varied, there appeared to be little effect on the measured derivatives as a result of the change in amplitude of the oscillation.

  8. Clementine High Resolution Camera Mosaicking Project. Volume 17; CL 6017; 0 deg to 80 deg S Latitude, 330 deg E Longitude; 1

    NASA Technical Reports Server (NTRS)

    Malin, Michael; Revine, Michael; Boyce, Joseph M. (Technical Monitor)

    1998-01-01

    This compact disk (CD) is part of the Malin Space Science Systems (MSSS) effort to mosaic Clementine I high resolution (HiRes) camera lunar images. These mosaics were developed through calibration and semi-automated registration against the recently released geometrically and photometrically controlled Ultraviolet/Visible (UV/Vis) Basemap Mosaic, which is available through the PDS, as CD-ROM volumes CL_3001-3015. The HiRes mosaics are compiled from non-uniformity corrected, 750 nanometer ("D") filter high resolution observations from the HiRes imaging system onboard the Clementine Spacecraft. These mosaics are spatially warped using the sinusoidal equal-area projection at a scale of 20 m/pixel. The geometric control is provided by the 100 m/pixel U.S. Geological Survey (USGS) Clementine Basemap Mosaic compiled from the 750 nm Ultraviolet/Visible Clementine imaging system. Calibration was achieved by removing the image nonuniformity largely caused by the HiRes system's light intensifier. Also provided are offset and scale factors, achieved by a fit of the HiRes data to the corresponding photometrically calibrated UV/Vis basemap that approximately transform the 8-bit HiRes data to photometric units. The mosaics on this CD were compiled from sub-polar data (latitudes 80 degrees South to 80 degrees North; -80 to +80) within the longitude range 0-30 deg E. The mosaics are divided into tiles that cover approximately 1.75 degrees of latitude and span the longitude range of the mosaicked frames. Images from a given orbit are map projected using the orbit's nominal central latitude. This CD contains ancillary data files that support the HiRes mosaic. These files include browse images with UV/Vis context stored in a Joint Photographic Experts Group (JPEG) format, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the "FILES

  9. Infrared astronomical satellite (IRAS) catalogs and atlases. Volume 3: The point source catalog declination range 30 deg greater than delta greater than 0 deg

    SciTech Connect

    Not Available

    1988-01-01

    The Infrared Astronomical Satellite (IRAS) was launched January 26, 1983. During its 300-day mission, IRAS surveyed over 96 pct of the celestial sphere at four infrared wavelengths, centered approximately at 12, 25, 60, and 100 microns. This is Volume 3, The Point Source Catalog Declination Range 30 deg greater than delta greater than 0 deg.

  10. Infrared astronomical satellite (IRAS) catalogs and atlases. Volume 4: The point source catalog declination range 0 deg greater than delta greater than -30 deg

    SciTech Connect

    Not Available

    1988-01-01

    The Infrared Astronomical Satellite (IRAS) was launched 26 January 1983. During its 300-day mission, it surveyed over 96 pct of the celestial sphere at four infrared wavelengths, centered approximately at 12, 25, 60, and 100 microns. This is Volume 4, The Point Source Catalog Declination Range 0 deg greater than delta greater than -30 deg.

  11. Infrared astronomical satellite (IRAS) catalogs and atlases. Volume 5: The point source catalog declination range -30 deg greater than delta greater than -50 deg

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The Infrared Astronomical Satellite (IRAS) was launched January 26, 1983. During its 300-day mission, IRAS surveyed over 96 pct of the celestial sphere at four infrared wavelengths, centered approximately at 12, 25, 60, and 100 microns. This is Volume 5, The Point Source Catalog Declination Range -30 deg greater than delta greater than -50 deg.

  12. Infrared astronomical satellite (IRAS) catalogs and atlases. Volume 2: The point source catalog declination range 90 deg greater than delta greater than 30 deg

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The Infrared Astronomical Satellite (IRAS) was launched January 26, 1983. During its 300-day mission, IRAS surveyed 96 pct of the celestial sphere at four infrared wavelengths, centered approximately at 12, 25, 60, and 100 microns. This is Volume 2, The Point Source Catalog Declination Range 90 deg greater than delta greater than 30 deg.

  13. PDZ domains determine the native oligomeric structure of the DegP (HtrA) protease.

    PubMed

    Sassoon, N; Arié, J P; Betton, J M

    1999-08-01

    DegP (HtrA) is a periplasmic heat shock serine protease of Escherichia coli that degrades misfolded proteins at high temperatures. Biochemical and biophysical experiments have indicated that the purified DegP exists as a hexamer. To examine whether the PDZ domains of DegP were required for oligomerization, we constructed a DegP variant lacking both PDZ domains. This truncated variant, DegPDelta, exhibited no proteolytic activity but exerted a dominant-negative effect on growth at high temperatures by interfering with the functional assembly of oligomeric DegP. Thus, the PDZ domains contain information necessary for proper assembly of the functional hexameric structure of DegP. PMID:10417648

  14. A 360-deg Digital Image Correlation system for materials testing

    NASA Astrophysics Data System (ADS)

    Genovese, K.; Cortese, L.; Rossi, M.; Amodio, D.

    2016-07-01

    The increasing research interest toward natural and advanced engineered materials demands new experimental protocols capable of retrieving highly dense sets of experimental data on the full-surface of samples under multiple loading conditions. Such information, in fact, would allow to capture the possible heterogeneity and anisotropy of the material by using up-to-date inverse characterization methods. Although the development of object-specific test protocols could represent the optimal choice to address this need, it is unquestionable that universal testing machines (UTM) remain the most widespread and versatile option to test materials and components in both academic and industrial contexts. A major limitation of performing standard material tests with UTM, however, consists in the scarce information obtainable with the commonly associated sensors since they provide only global (LVDTs, extensometers, 2D-video analyzers) or local (strain gages) measures of displacement and strain. This paper presents a 3D Digital Image Correlation (DIC) system developed to perform highly accurate full-surface 360-deg measurements on either standard or custom-shaped samples under complex loading within universal testing machines. To this aim, a low cost and easy to setup video rig was specifically designed to overcome the practical limitations entailed with the integration of a multi-camera system within an already existing loading frame. In particular, the proposed system features a single SLR digital camera moved through multiple positions around the specimen by means of a large rotation stage. A proper calibration and data-processing procedure allows to automatically merge the experimental data obtained from the multiple views with an accuracy of 10-2 m m . The results of a full benchmarking of the metrological performances of the system are here reported and discussed together with illustrative examples of full-360-deg shape and deformation measurements on a Grade X65 steel

  15. De Novo Transcriptome Sequencing Analysis and Comparison of Differentially Expressed Genes (DEGs) in Macrobrachium rosenbergii in China

    PubMed Central

    Liu, Qigen

    2014-01-01

    Giant freshwater prawn (GFP; Macrobrachium rosenbergii) is an exotic species that was introduced into China in 1976 and thereafter it became a major species in freshwater aquaculture. However the gene discovery in this species has been limited to small-scale data collection in China. We used the next generation sequencing technology for the experiment; the transcriptome was sequenced of samples of hepatopancreas organ in individuals from 4 GFP groups (A1, A2, B1 and B2). De novo transcriptome sequencing generated 66,953 isogenes. Using BLASTX to search the Non-redundant (NR), Search Tool for the Retrieval of Interacting Genes (STRING), and Kyoto Encyclopedia of Genes and Genome (KEGG) databases; 21,224 unigenes were annotated, 9,552 matched unigenes with the Gene Ontology (GO) classification; 5,782 matched unigenes in 25 categories of Clusters of Orthologous Groups of proteins (COG) and 20,859 unigenes were consequently assigned to 312 KEGG pathways. Between the A and B groups 147 differentially expressed genes (DEGs) were identified; between the A1 and A2 groups 6,860 DEGs were identified and between the B1 and B2 groups 5,229 DEGs were identified. After enrichment, the A and B groups identified 38 DEGs, but none of them were significantly enriched. The A1 and A2 groups identified 21,856 DEGs in three main categories based on functional groups: biological process, cellular_component and molecular function and the KEGG pathway defined 2,459 genes had a KEGG Ortholog - ID (KO-ID) and could be categorized into 251 pathways, of those, 9 pathways were significantly enriched. The B1 and B2 groups identified 5,940 DEGs in three main categories based on functional groups: biological process, cellular_component and molecular function, and the KEGG pathway defined 1,543 genes had a KO-ID and could be categorized into 240 pathways, of those, 2 pathways were significantly enriched. We investigated 99 queries (GO) which related to growth of GFP in 4 groups. After enrichment we

  16. 360-deg profile noncontact measurement using a neural network

    NASA Astrophysics Data System (ADS)

    Chang, Ming; Tai, Wen-Chih

    1995-12-01

    A new approach to automatic 3D shape measurement is presented and verified by experiments. This approach, based on neural network theory, can automatically and accurately obtain the profile of diffuse 3D objects by using a projected laser stripe. When the laser stripe is projected on an object, the line image of the laser light is grasped by a CCD camera. Using neural network theory, a relationship between the laser stripe image in the CCD camera and the related absolute position in space can be established. Thus the spatial coordinates of a measured line image in a CCD camera can be obtained according to the output value of the neural network. By processing a series of laser line images from the discrete angular positions of an object, a complete 3D profile can be reconstructed. Theoretical analysis and experimental systems are presented. Experimental results show that this approach can determine the 360-deg profile of an object with an accuracy of 0.4 mm.

  17. An investigation of the aerodynamic characteristics of a 0.00548 scale model (model no. 486) of the space shuttle 146-inch diameter solid rocket booster at angels of attack from 113 deg to 180 deg in the AEDC PWT 4-foot transonic wind tunnel (SA16F)

    NASA Technical Reports Server (NTRS)

    Ramsey, P. E.

    1976-01-01

    An experimental investigation (SA16F) was conducted in the AEDC PWT 4T to determine the entry static stability of a 0.00548 scale space shuttle solid rocket booster (SRB). The primary objective was to improve the definition of the aerodynamic characteristics in the angle of attack range beyond 90 deg in the vicinity of the entry trim point. The SRB scale model consisted of the reentry configuration with all major protuberances. A simulated heat shield around the engine nozzle was also included. Data were obtained for a 60 deg side mounted sting and a straight nose mounted sting. The angle of attack range for the side mounted sting was 113 deg to 147 deg and for the nose mounted sting 152 deg to 187 deg. The Mach number range consisted of 0.4 to 1.2 at roll angles of 0 and 90 deg. The resulting 6-component aerodynamic force data was presented as the variation of coefficients with angle of attack for each Mach number and roll angle.

  18. The diameter of Juno from its occultation of AG + 0 deg 1022

    NASA Technical Reports Server (NTRS)

    Millis, R. L.; Wasserman, L. H.; Bowell, E.; Franz, O. G.; White, N. M.; Lockwood, G. W.; Nye, R.; Bertram, R.; Klemola, A.; Dunham, E.; Morrison, D.

    1981-01-01

    The occultation on Dec. 11, 1979, of AG + 0 deg 1022 by Juno was observed photoelectrically from 15 sites distributed across the occultation track. The observations are well represented by a mean elliptical limb profile having semimajor and semiminor axes of 145.2 + or 0.8 and 122.8 + or - 1.9 km, respectively. The corresponding effective diameter of Juno is 267 + or - 5 km, where the uncertainty has been conservatively increased to reflect the presence of limb irregularities clearly seen in the observations. Published radiometric and polarimetric diameters for Juno are 6% to 7% smaller than the occultation result. No secondary occultations attributable to possible satellites of Juno were recorded at any of 23 photoelectrically equipped observing sites.

  19. Observations of the 8 December 1987 occultation of AG +40 deg 0783 by 324 Bamberga

    NASA Technical Reports Server (NTRS)

    Millis, R. L.; Wasserman, L. H.; Franz, O. G.; Bowell, E.; Nye, R. A.; Thompson, D. T.; White, N. M.; Hubbard, W. B.; Eplee, R. E., Jr.; Yeomans, D. K.

    1989-01-01

    The occultation of AG+40 deg 0783 by 324 Bamberga on 8 December 1987 was observed at 13 sites in the United States, Japan, and China. At four sites the event was observed photoelectrically; the other observations were visual. A least-squares fit of a circular limb profile to the data gives a diameter of 227.6 + or - 1.9 km. However, this solution is inconsistent with a negative visual observation near the northern edge of the ground track. The inconsistency cannot be removed by assuming an elliptical profile. The data suggest that Bamberga, despite its low-amplitude lightcurve, may depart significantly from a spherical or ellipsoidal shape. The asteroid also appears to be at least 10 percent smaller than indicated by infrared radiometry.

  20. Global behavior of the height/seasonal structure of tides between 40 deg and 60 deg latitude

    NASA Technical Reports Server (NTRS)

    Manson, A. H.; Meek, C. E.; Teitelbaum, H.; Fraser, G. J.; Smith, M. J.; Clark, R. R.; Schminder, R.; Kuerschner, D.

    1989-01-01

    The radars utilized are meteor (2), medium frequency (2) and the new low frequency (1) systems: analysis techniques were exhaustively studied internally and comparatively and are not thought to affect the results. Emphasis is placed upon the new height-time contours of 24-, 12-h tidal amplitudes and phases, which best display height and seasonal structures; where possible high resolution (10 d) is used (Saskatoon), but all stations provide monthly mean resolution. At these latitudes the diurnal tide is generally smaller than the semidiurnal, and displays more variability. However, there is a tendency for vertical wavelengths and amplitudes to be larger during summer months. On occasions in winter and fall, wavelengths may be less than 50 km. The dominant semidiurnal tide shows significant regular season structure; wavelengths are generally small (about 50 km) in winter, large in summer (equal to or greater than 100 km), and these states are separated by rapid equinoctial transitions. There is some evidence for less regularity toward 40 deg. Coupling with mean winds is apparent. Data from earlier ATMAP campaigns are mentioned, and reasons for their inadequacies presented.

  1. The development of the July 1989 1 deg x 1 deg and 30' x 30' terrestrial mean free-air anomaly data bases

    NASA Technical Reports Server (NTRS)

    Kim, Jeong-Hee; Rapp, Richard H.

    1990-01-01

    In June 1986 a 1 x 1 deg/mean free-air anomaly data file containing 48955 anomalies was completed. In August 1986 a 30 x 30 min mean free-air anomaly file was defined containing 31787 values. For the past three years data has been collected to upgrade these mean anomaly files. The primary emphasis was the collection of data to be used for the estimation of 30 min means anomalies in land areas. The emphasis on land areas was due to the anticipated use of 30 min anomalies derived from satellite altimeter data in the ocean areas. There were 10 data sources in the August 1986 file. Twenty-eight sources were added based on the collection of both point and mean anomalies from a number of individuals and organizations. A preliminary 30 min file was constructed from the 38 data sources. This file was used to calculate 1 x 1 deg mean anomalies. This 1 x 1 deg file was merged with a 1 x 1 deg file which was a merger of the June 1986 file plus a 1 x 1 deg file made available by DMA Aerospace Center. Certain bad 30 min anomalies were identified and deleted from the preliminary 30 min file leading to the final 30 min file (the July 1989 30 min file) with 66990 anomalies and their accuracy. These anomalies were used to again compute 1 x 1 deg anomalies which were merged with the previous June 86 DMAAC data file. The final 1 x 1 deg mean anomaly file (the July 89 1 x 1 deg data base) contained 50793 anomalies and their accuracy. The anomaly data files were significantly improved over the prior data sets in the following geographic regions: Africa, Scandinavia, Canada, United States, Mexico, Central and South America. Substantial land areas remain where there is little or no available data.

  2. Flexure fatigue testing of 90 deg graphite/epoxy composites

    NASA Technical Reports Server (NTRS)

    Peck, Ann Nancy W.

    1995-01-01

    3-point flexure tests of 90 deg graphite/epoxy specimens. Investigations will include the volume scale effect as well as frequency and span-to-thickness ratio effects. Prior to the start of the experimental study, an analytical study using finite element modeling will be performed to investigate the span-to-thickness effect. The ratio of transverse flexure stress to shear stress will be monitored and its values predicted by the FEM analysis compared with the value obtained using a 'strength of materials' based approach.

  3. THE ARECIBO LEGACY FAST ALFA SURVEY. VIII. H I SOURCE CATALOG OF THE ANTI-VIRGO REGION AT {delta} = +25 DEG

    SciTech Connect

    Martin, Ann M.; Giovanelli, Riccardo; Haynes, Martha P.; Stierwalt, Sabrina; Saintonge, Amelie; Hoffman, G. Lyle; Kent, Brian R. E-mail: riccardo@astro.cornell.edu E-mail: sabrina@astro.cornell.edu E-mail: hoffmang@lafayette.edu

    2009-08-01

    We present a fourth catalog of H I sources from the Arecibo Legacy Fast ALFA (ALFALFA) Survey. We report 541 detections over 136 deg{sup 2}, within the region of the sky having 22{sup h} < {alpha} < 03{sup h} and 24 deg. < {delta} < 26 deg. This complements a previous catalog in the region 26 deg. < {delta} < 28 deg. We present here the detections falling into three classes: (1) extragalactic sources with signal-to-noise ratio (S/N)>6.5, where the reliability of the catalog is better than 95%; (2) extragalactic sources 5.0 < S/N < 6.5 and a previously measured optical redshift that corroborates our detection; or (3) High Velocity Clouds (HVCs), or subcomponents of such clouds, in the periphery of the Milky Way. Of the 541 objects presented here, 90 are associated with HVCs, while the remaining 451 are identified as extragalactic objects. Optical counterparts have been matched with all but one of the extragalactic objects.

  4. Observation of the middle atmospheric thermal tides using lidar measurements over Mauna Loa Observatory (19.5 deg N, 155.6 deg W)

    NASA Technical Reports Server (NTRS)

    Leblanc, Thierry; McDermid, I. Stuart

    1998-01-01

    Temperature measurements in the middle atmosphere using Rayleigh lidars have been performed for several decades now. The high accuracy and vertical resolution provided by lidars allow to study the temperature variability at various scales with high confidence levels. One of the numerous applications is the study of the middle atmospheric thermal tides. Although Rayleigh lidar measurements are basically possible only at nighttime, diurnal and semidiurnal components can often be extracted if the results are taken with care and correctly interpreted. Using results from more than 200 hours of nighttime measurements obtained by lidar in October 1996 and 1997 at Mauna Loa Observatory, Hawaii, a study of the middle atmospheric (25-90 km) thermal tides is presented in this paper. The amplitudes and phases of the diurnal and semidiurnal components were calculated for some altitudes where the fits converged significantly, and compared to that of the Global Scale Wave Model (GSWM).

  5. Primary production estimates from recordings of solar-stimulated fluorescence in the equatorial Pacific at 150 deg W

    NASA Technical Reports Server (NTRS)

    Stegmann, P. M.; Lewis, M. R.; Davis, C. O.; Cullen, J. J.

    1992-01-01

    Biological, optical, and hydrographical data were collected on the WEC88 cruise along 150 deg W and during a 6-day time-series station on the equator during February/March 1988. This area was characterized by a subsurface chlorophyll maximum (SCM), located at 50-70 m depth at the equator and descending down to 120-125 m at the north and south end of the transect. Highest primary production rates were near-surface and confined to the equatorial region and stations between 7 deg and 11 deg N. To determine the relationship between solar-stimulated fluorescence (centered at 683 nm wavelength) and primary production, a production-fluorescence model based on phytoplankton physiology and marine optics is described. Results of model calculations predict that there is a linear relation between production and fluorescence. A comparison between morning and midday measurements of the production-fluorescence relation showed that there was some difference between the two, whereas evening measurements, on the other hand, were distinctly different from the morning/midday ones. This seems to suggest that diurnal variations contribute significantly to variability in the quantum yield of photochemical processes. The ratio of the quantum yield of photosynthesis to the quantum yield of fluorescence ranged between 0.24 and 0.44 molC/Ein for all stations. The highest value for this ratio occurred at the equatorial stations, indicating that latitudinal variability could have an effect on the production-fluorescence relation.

  6. Rotary balance data for a typical single-engine general aviation design for an angle-of-attack range of 8 deg to 90 deg. 2: Influence of horizontal tail location for Model D

    NASA Technical Reports Server (NTRS)

    Barnhart, B.

    1982-01-01

    The influence of horizontal tail location on the rotational flow aerodynamics is discussed for a 1/6-scale general aviation airplane model. The model was tested using various horizontal tail positions, with both a high and a low-wing location and for each of two body lengths. Data were measured, using a rotary balance, over an angle-of-attack range of 8 to 90 deg, and for clockwise and counter-clockwise rotations covering an Omega b/2V range of 0 to 0.9.

  7. DSMC calculations for 70-deg blunted cone at 3.2 km/s in nitrogen

    NASA Technical Reports Server (NTRS)

    Moss, J. N.; Price, J. M.; Dogra, V. K.

    1995-01-01

    Numerical results obtained with the direct simulation Monte Carlo (DSMC) method are presented for Mach 15.6 nitrogen flow about a 70-deg spherically blunted cone at zero incidence. This flow condition is one of several generated in the Large Energy National Shock (LENS) tunnel during tests of a 15.24 cm diameter model with an afterbody sting. The freestream Knudsen number, based on model diameter, is 0.0023. The focus of the DSMC calculations is to characterize the near wake flow under conditions where rarefaction effects may influence afterbody aerothermal loads. This report provides information concerning computational details along with flowfield and surface quantities. Calculations show that the flow enveloping the test model is in thermal nonequilibrium and a sizable vortex develops in the near wake. Along the model baseplane the heating rates are about 0.6 percent of the forebody stagnation value while the maximum heating along the sting is about 4.2 percent of the forebody stagnation value. Comparison of a Navier-Stokes solution with the present calculations show good agreement for surface heating, pressure, and skin friction results.

  8. Estimating new production in the equatorial Pacific Ocean at 150 deg W

    NASA Technical Reports Server (NTRS)

    Dugdale, Richard C.; Wilkerson, Frances P.; Barber, Richard T.; Chavez, Francisco P.

    1992-01-01

    A major goal of the WEC88 cruise of the R/V Wecoma to the equatorial Pacific (made in February-March 1988) was to establish rates of new production along a meridional section at 150 deg W and to compare these measured rates with the relatively high values for the equatorial Pacific that had been reported previously using indirect methods and models. Production values were obtained from the traditional approach using N-15 labeled nitrate uptake, and by using C-14 fixation values multiplied by f (proportion of new production) from various sources: from N-15 data, from a C-14 fixation-versus-f relationship, or from a nitrate-versus-f relationship. The ratios of directly measured nitrate and carbon uptake and the ratios of nitrate to nitrate plus ammonium uptake, i.e., values of f, agree well; values of f calculated from carbon uptake or from nitrate concentration are overestimates for the equatorial upwelling region. Carbon-to-nitrogen uptake ratios measured with C-14 and N-15, respectively, approximate the Redfield molar ratio, 6.6 C:N. The overall mean value of f (0.17) helps confirm the view that the low primary production in the enriched eastern equatorial Pacific is due to failure of the nitrate-uptake system.

  9. Vortex flap flow reattachment line and subsonic longitudinal aerodynamic data on 50 deg to 74 deg Delta wings on common fuselage

    NASA Technical Reports Server (NTRS)

    Frink, N. T.; Huffman, J. K.; Johnson, T. D., Jr.

    1983-01-01

    Positions of the primary vortex flow reattachment line and longitudinal aerodynamic data were obtained at Mach number 0.3 for a systematic series of vortex flaps on delta wing body configurations with leading edge sweeps of 50, 58, 66, and 74 deg. The investigation was performed to study the parametric effects of wing sweep, vortex flap geometry and deflection, canards, and trailing edge flaps on the location of the primary vortex reattachment line relative to the flap hinge line. The vortex reattachment line was located via surface oil flow photographs taken at selected angles of attack. Force and moment measurements were taken over an angle of attack range of -1 deg to 22 deg at zero sideslip angle for many configurations to further establish the data base and to assess the aforementioned parametric effects on longitudinal aerodynamics. Both the flow reattachment and aerodynamic data are presented.

  10. Developing an optimally estimated earth gravity model to degree and order 360 from a global set of 30 deg x 30 deg mean surface gravity anomalies

    NASA Astrophysics Data System (ADS)

    Gleason, D. M.

    An optimally estimated earth gravity model (EGM), consisting of a set of geopotential coefficients through a maximum degree and order of 360, has been created from a global set of 259,200 30 deg by 30 deg surface mean gravity anomalies. The model is optimal in the sense that its derivation follows the principles of least-squares collocation which results in the coefficients' error variance/covariance matrix having a minimal trace value. This paper presents: (1) an overview of the mathematical and geodetic principles behind the construction of the model, (2) a discussion on the practical concerns and problems associated with the implementation of these principles on a present-day high speed computer, (3) a brief description of the global 30 deg input mean anomaly file used, (4) an analysis of the statistical properties of the coefficients and their accuracies, and (5) a prognosis for the future.

  11. Rotary balance data for a single-engine agricultural airplane configuration for an angle-of-attack range of 8 deg to 90 deg

    NASA Technical Reports Server (NTRS)

    Mulcay, W. J.; Chu, J.

    1980-01-01

    Aerodynamic characteristics obtained in a helical flow environment utilizing a rotary balance located in the Langley spin tunnel are presented in plotted form for a 1/10 scale single engine agricultural airplane model. The configurations tested include the basic airplane, various wing leading edge and wing tip devices, elevator, aileron, and rudder control settings, and other modifications. Data are presented without analysis for an angle of attack range of 8 deg to 90 deg, and clockwise and counter-clockwise rotations covering a spin coefficient range from 0 to .9.

  12. The DEG15 Serine Protease Cleaves Peroxisomal Targeting Signal 2-Containing Proteins in Arabidopsis1[OA

    PubMed Central

    Schuhmann, Holger; Huesgen, Pitter F.; Gietl, Christine; Adamska, Iwona

    2008-01-01

    Two distinct peroxisomal targeting signals (PTSs), the C-terminal PTS1 and the N-terminal PTS2, are defined. Processing of the PTS2 on protein import is conserved in higher eukaryotes. Recently, candidates for the responsible processing protease were identified from plants (DEG15) and mammals (TYSND1). We demonstrate that plants lacking DEG15 show an expressed phenotype potentially linked to reduced β-oxidation, indicating the impact of protein processing on peroxisomal functions in higher eukaryotes. Mutational analysis of Arabidopsis (Arabidopsis thaliana) DEG15 revealed that conserved histidine, aspartic acid, and serine residues are essential for the proteolytic activity of this enzyme in vitro. This indicates that DEG15 and related enzymes are trypsin-like serine endopeptidases. Deletion of a plant-specific stretch present in the protease domain diminished, but did not abolish, the proteolytic activity of DEG15 against the PTS2-containing glyoxysomal malate dehydrogenase. Fluorescence microscopy showed that a DEG15-green fluorescent protein fusion construct is targeted to peroxisomes in planta. In vivo studies with isolated homozygous deg15 knockout mutants and complemented mutant lines suggest that this enzyme mediates general processing of PTS2-containing proteins. PMID:18952862

  13. Flight Reynolds number effects on a fighter-type, circular-arc-19 deg conic boattail nozzle at subsonic speeds

    NASA Technical Reports Server (NTRS)

    Chamberlin, R.

    1974-01-01

    A circular-arc - conic boattail nozzle, typical of those used on a twin engine fighter, was tested on an underwing nacelle mounted on an F-106B aircraft. The boattail had a radius ratio r/r sub c of 0.41 and a terminal boattail angle of approximately 19 deg. The gas generator was a J85-GE-13 turbojet engine. The effects of Reynolds number and angle of attack on boattail pressure drag and boattail pressure profiles were investigated. Increasing Reynolds number resulted in reduced boattail drag at both Mach numbers of 0.6 and 0.9.

  14. Changes in size and compliance of the calf after 30 days of simulated microgravity

    NASA Technical Reports Server (NTRS)

    Convertino, Victor A.; Doerr, Donald F.; Stein, Stewart L.

    1989-01-01

    The hypothesis that reducing muscle compartment by a long-term exposure to microgravity would cause increased leg venous compliance was tested in eight men who were assessed for vascular compliance and for serial circumferences of the calf before and after 30 days of continuous 6-deg head-down bed rest. It was found that head-down bed rest caused decreases in the calculated calf volume and the calf-muscle compartment, as well as increases in calf compliance. The percent increases in calf compliance correlated significantly with decreases in calf muscle compartment.

  15. Subsonic balance and pressure investigation of a 60 deg delta wing with leading edge devices

    NASA Technical Reports Server (NTRS)

    Tingas, S. A.; Rao, D. M.

    1982-01-01

    Low supersonic wave drag makes the thin highly swept delta wing the logical choice for use on aircraft designed for supersonic cruise. However, the high-lift maneuver capability of the aircraft is limited by severe induced-drag penalties attributed to loss of potential flow leading-edge suction. This drag increase may be alleviated through leading-edge flow control to recover lost aerodynamic thrust through either retention of attached leading-edge flow to higher angles of attack or exploitation of the increased suction potential of separation-induced vortex flow. A low-speed wind-tunnel investigation was undertaken to examine the high-lift devices such as fences, chordwise slots, pylon vortex generators, leading-edge vortex flaps, and sharp leading-edge extensions. The devices were tested individually and in combinations in an attempt to improve high-alpha drag performance with a minimum of low-alpha drag penalty. This report presents an analysis of the force, moment, and static pressure data obtained in angles of attack up to 23 deg, at Mach and Reynolds numbers of 0.16 and 3.85 x 10 to the 6th power per meter, respectively. The results indicate that all the devices produced drag and longitudinal/lateral stability improvements at high lift with, in most cases, minor drag penalties at low angles of attack.

  16. Rotary balance data for a typical single-engine general aviation design for an angle-of-attack range of 20 to 90 deg. 3: Influence of control deflection on predicted model D spin modes

    NASA Technical Reports Server (NTRS)

    Ralston, J. N.; Barnhart, B. P.

    1984-01-01

    The influence of control deflections on the rotational flow aerodynamics and on predicted spin modes is discussed for a 1/6-scale general aviation airplane model. The model was tested for various control settings at both zero and ten degree sideslip angles. Data were measured, using a rotary balance, over an angle-of-attack range of 30 deg to 90 deg, and for clockwise and counter-clockwise rotations covering an omegab/2V range of 0 to 0.5.

  17. Heat-Transfer Measurements on the Apexes of Two 60 deg Sweptback Delta Wings (Panel Semiapex Angle of 30 deg) Having 0 deg and 45 deg Dihedral at a Mach Number of 4.95

    NASA Technical Reports Server (NTRS)

    Gunn, Charles R.

    1961-01-01

    An experimental investigation was conducted to evaluate the heat-transfer rates at the apex of two 60 degree sweptback delta wings (panel semi-apex angle of 30 degrees) having cylindrical leading edges and 0 degrees and 45 degree positive dihedral. The models tested might correspond to the first several feet of a hypersonic reentry vehicle. The tests were conducted at a Mach number of 4.95 and a stagnation temperature of 400 F. nominal test-section unit Reynolds numbers varied from 2 x 10(exp 6) to 12 x 10(exp 6) per foot. The results of the investigation indicated that the laminar heat-transfer distributions (ratio of local to stagnation-line heating rate) about the models normal to the leading edges were in close agreement with two-dimensional blunt-body theory. The three-dimensional stagnation point heat-transfer rate on the 0 degree dihedral model was in excellent agreement with theory and the stagnation-line heat transfer on the straight portion of the leading edge of both models approached a constant level 12 percent above the theoretical stagnation-line level on an isolated swept infinite cylinder. When the heating rates on the 45 degree dihedral model (planform sweep of 69.3 degree) were compared with those on the 0 degree dihedral model (planform sweep of 60 degrees) at equal angles of attack and equal lifts greater than zero, the stagnation-line heating rates on the 45 degrees dihedral model were, in general, considerably lower as a result of the difference in effective sweeps of the leading edges. On the wing panels inboard from the stagnation lines, the differences in heating were very small. The stagnation-line heat-transfer variation with angle of attack, the shift in stagnation-line location, and the reduction in stagnation-line heat transfer resulting from the increase in effective sweep when positive dihedral is incorporated into a constant-panel 0 degree dihedral wing, all agreed with the results of a theoretical study made of highly swept delta

  18. Role of the PDZ Domains in Escherichia coli DegP Protein▿

    PubMed Central

    Iwanczyk, Jack; Damjanovic, Daniela; Kooistra, Joel; Leong, Vivian; Jomaa, Ahmad; Ghirlando, Rodolfo; Ortega, Joaquin

    2007-01-01

    PDZ domains are modular protein interaction domains that are present in metazoans and bacteria. These domains possess unique structural features that allow them to interact with the C-terminal residues of their ligands. The Escherichia coli essential periplasmic protein DegP contains two PDZ domains attached to the C-terminal end of the protease domain. In this study we examined the role of each PDZ domain in the protease and chaperone activities of this protein. Specifically, DegP mutants with either one or both PDZ domains deleted were generated and tested to determine their protease and chaperone activities, as well as their abilities to sequester unfolded substrates. We found that the PDZ domains in DegP have different roles; the PDZ1 domain is essential for protease activity and is responsible for recognizing and sequestering unfolded substrates through C-terminal tags, whereas the PDZ2 domain is mostly involved in maintaining the hexameric cage of DegP. Interestingly, neither of the PDZ domains was required for the chaperone activity of DegP. In addition, we found that the loops connecting the protease domain to PDZ1 and connecting PDZ1 to PDZ2 are also essential for the protease activity of the hexameric DegP protein. New insights into the roles of the PDZ domains in the structure and function of DegP are provided. These results imply that DegP recognizes substrate molecules targeted for degradation and substrate molecules targeted for refolding in different manners and suggest that the substrate recognition mechanisms may play a role in the protease-chaperone switch, dictating whether the substrate is degraded or refolded. PMID:17277057

  19. Simplified 2DEG carrier concentration model for composite barrier AlGaN/GaN HEMT

    SciTech Connect

    Das, Palash Biswas, Dhrubes

    2014-04-24

    The self consistent solution of Schrodinger and Poisson equations is used along with the total charge depletion model and applied with a novel approach of composite AlGaN barrier based HEMT heterostructure. The solution leaded to a completely new analytical model for Fermi energy level vs. 2DEG carrier concentration. This was eventually used to demonstrate a new analytical model for the temperature dependent 2DEG carrier concentration in AlGaN/GaN HEMT.

  20. Evolution of secondary phases in austenitic stainless steels during long-term exposures at 600, 650 and 800 deg. C

    SciTech Connect

    Vach, Marian Kunikova, Terezia; Domankova, Maria; Sevc, Peter; Caplovic, Lubomir; Gogola, Peter; Janovec, Jozef

    2008-12-15

    Three austenitic steels (18Cr-8Ni, 18Cr-10Ni, 21Cr-30Ni), used for long-term applications at temperatures between 600 and 800 deg. C were investigated. In the investigation, metallography, transmission electron microscopy, selected area electron diffraction, energy dispersive X-ray spectroscopy, and scanning electron microscopy were used. In additional to the experimental measurements, thermodynamic predictions were done using the ThermoCalc software and the non-commercial database STEEL16F. Various combinations of M{sub 23}C{sub 6}, sigma, and MC phases were identified in the austenite matrix of these steels. It was confirmed experimentally that extra large particles (up to 10 {mu}m) observed in the 21Cr-30Ni steel are M{sub 23}C{sub 6}, even though this carbide was not predicted as the equilibrium carbide at service temperature (800 deg. C). The analytical-experimental approach, combining thermodynamic predictions and experimental measurements, was found to be reliable for the characterization of austenitic steels.

  1. Modeling on oxide dependent 2DEG sheet charge density and threshold voltage in AlGaN/GaN MOSHEMT

    NASA Astrophysics Data System (ADS)

    Panda, J.; Jena, K.; Swain, R.; Lenka, T. R.

    2016-04-01

    We have developed a physics based analytical model for the calculation of threshold voltage, two dimensional electron gas (2DEG) density and surface potential for AlGaN/GaN metal oxide semiconductor high electron mobility transistors (MOSHEMT). The developed model includes important parameters like polarization charge density at oxide/AlGaN and AlGaN/GaN interfaces, interfacial defect oxide charges and donor charges at the surface of the AlGaN barrier. The effects of two different gate oxides (Al2O3 and HfO2) are compared for the performance evaluation of the proposed MOSHEMT. The MOSHEMTs with Al2O3 dielectric have an advantage of significant increase in 2DEG up to 1.2 × 1013 cm‑2 with an increase in oxide thickness up to 10 nm as compared to HfO2 dielectric MOSHEMT. The surface potential for HfO2 based device decreases from 2 to ‑1.6 eV within 10 nm of oxide thickness whereas for the Al2O3 based device a sharp transition of surface potential occurs from 2.8 to ‑8.3 eV. The variation in oxide thickness and gate metal work function of the proposed MOSHEMT shifts the threshold voltage from negative to positive realizing the enhanced mode operation. Further to validate the model, the device is simulated in Silvaco Technology Computer Aided Design (TCAD) showing good agreement with the proposed model results. The accuracy of the developed calculations of the proposed model can be used to develop a complete physics based 2DEG sheet charge density and threshold voltage model for GaN MOSHEMT devices for performance analysis.

  2. DEGS2 polymorphism associated with cognition in schizophrenia is associated with gene expression in brain

    PubMed Central

    Ohi, K; Ursini, G; Li, M; Shin, J H; Ye, T; Chen, Q; Tao, R; Kleinman, J E; Hyde, T M; Hashimoto, R; Weinberger, D R

    2015-01-01

    A genome-wide association study of cognitive deficits in patients with schizophrenia in Japan found association with a missense genetic variant (rs7157599, Asn8Ser) in the delta(4)-desaturase, sphingolipid 2 (DEGS2) gene. A replication analysis using Caucasian samples showed a directionally consistent trend for cognitive association of a proxy single-nucleotide polymorphism (SNP), rs3783332. Although the DEGS2 gene is expressed in human brain, it is unknown how DEGS2 expression varies during human life and whether it is affected by psychiatric disorders and genetic variants. To address these questions, we examined DEGS2 messenger RNA using next-generation sequencing in postmortem dorsolateral prefrontal cortical tissue from a total of 418 Caucasian samples including patients with schizophrenia, bipolar disorder and major depressive disorder. DEGS2 is expressed at very low levels prenatally and increases gradually from birth to adolescence and consistently expressed across adulthood. Rs3783332 genotype was significantly associated with the expression across all subjects (F3,348=10.79, P=1.12 × 10−3), particularly in control subjects (F1,87=13.14, P=4.86 × 10−4). Similar results were found with rs715799 genotype. The carriers of the risk-associated minor allele at both loci showed significantly lower expression compared with subjects homozygous for the non-risk major allele and this was a consistent finding across all diagnostic groups. DEGS2 expression showed no association with diagnostic status after correcting for multiple testing (P>0.05). Our findings demonstrate that a SNP showing genome-wide association study significant association with cognition in schizophrenia is also associated with regulation of DEGS2 expression, implicating a molecular mechanism for the clinical association. PMID:25871975

  3. New high proper motion stars with declinations between -5(deg) and -30(deg) , and right ascensions between 13h 30m and 24h

    NASA Astrophysics Data System (ADS)

    Wroblewski, H.; Costa, E.

    1999-10-01

    Proper motions, positions, finding charts and magnitudes are given for 293 newly discovered stars with proper motions larger than 0.15 arcsec/year. They are located between -5(deg) and -30(deg) in declination, and 13h 30m and 24h in right ascension. Their blue photographic magnitudes range from approximately 13.0 to 18.5. Six stars of the above sample have proper motions larger than 0.4 (0.401 to 0.534) arcsec/year. An estimated precision level between 7 and 13 mas/year was achieved for the proper motions. Table~2 is only available in electronic form at the CDS via anonymous ftp 130.79.128.5 or http://cdsweb.u-strasbg.fr/Abstract.html and figures~2 are available in the on-line edition of the journal at http://www.edpsciences.com

  4. The stratospheric aerosol particle measurement by balloon at Syowa Station (69.00 deg S, 39.35 deg E): Outline of special sonde (rubber) campaign JARE 24

    NASA Technical Reports Server (NTRS)

    Iwasaka, Y.; Morita, T.; Itoh, T.; Shibazaki, K.; Makino, Y.; Tanaka, T.; Tsukamura, K.; Yano, T.; Kondoh, K.; Iwashita, G.

    1985-01-01

    During the period of AMA (Antarctic Middle Atmosphere), various style balloons were used to measure atmospheric parameters at Syowa Station (69.00 deg S, 39.35 deg E), Antarctica. The measurements which were made using balloons specially designed to monitor stratospheric aerosol particles are discussed. This type balloon was first used by JARE (Japan Antarctic Research Expedition) 24th Team in 1983. Until that time, the Japan Antarctic Research Expedition Team had been using only a large plastic balloon to monitor various minor constituents in the stratosphere. The plastic balloon was very useful, but it took a long time to arrange a balloon launching. Additionally, launching time strongly depended on weather conditions. A timely launching of the balloon was carried out with this specially designed sonde.

  5. Effect of a central redistribution of fluid volume on response to lower-body negative pressure

    NASA Technical Reports Server (NTRS)

    Tomaselli, Clare M.; Frey, Mary A. B.; Kenney, Richard A.; Hoffler, G. Wyckliffe

    1990-01-01

    Cardiovascular responses to lower-body negative pressure (LBNP) were studied following 1 hour of 6-deg head-down tilt to determine whether a redistribution of blood volume toward the central circulation modifies the subsequent response to orthostatic stress. Responses of 12 men, ages 30-39 years, were evaluated by electrocardiography, impedance cardiography, sphygmomanometry, and measurement of calf circumference. During the LBNP that followed head-down tilt, as compared with control LBNP (no preceding head-down tilt) subjects, had smaller stroke volume and cardiac output, greater total peripheral resistance, and less calf enlargement. These differences reflect differences in the variables immediately preceding LBNP. Magnitudes of the responses from pre-LBNP to each pressure stage of the LBNP procedure did not differ between protocols. Mean and diastolic arterial pressures were slightly elevated after LBNP-control, but they fell slightly during LBNP post-tilt.

  6. Dynamic response of a forward-swept-wing model at angles of attack up to 15 deg at a Mach number of 0.8. [Langley transonic dynamics tunnel tests

    NASA Technical Reports Server (NTRS)

    Doggett, R. V., Jr.; Ricketts, R. H.

    1980-01-01

    Root mean square (rms) bending moments for a dynamically scaled, aeroelastic wing of a proposed forward swept wing, flight demonstrator airplane are presented for angles of attack up to 15 deg at a Mach number of 0.8 The 0.6 size semispan model had a leading edge forward sweep of 44 deg and was constructed of composite material. In addition to broad band responses, individual rms responses and total damping ratios are presented for the first two natural modes. The results show that the rms response increases with angle of attack and has a peak value at an angle of attack near 13 deg. In general, the response was characteristic of buffeting and similar to results often observed for aft swept wings. At an angle of attack near 13 deg, however, the response had characteristics associated with approaching a dynamic instability, although no instability was observed over the range of parameters investigated.

  7. Sodium Lidar-observed Strong Inertia-gravity Wave Activities in the Mesopause Region over Fort Collins, Colorado (41 deg N, 105 deg W)

    NASA Technical Reports Server (NTRS)

    Li, Tao; She, C. -Y.; Liu, Han-Li; Leblanc, Thierry; McDermid, I. Stuart

    2007-01-01

    In December 2004, the Colorado State University sodium lidar system at Fort Collins, Colorado (41 deg N, 105 deg W), conducted an approximately 80-hour continuous campaign for the simultaneous observations of mesopause region sodium density, temperature, and zonal and meridional winds. This data set reveals the significant inertia-gravity wave activities with a period of approximately 18 hours, which are strong in both wind components since UT day 338 (second day of the campaign), and weak in temperature and sodium density. The considerable variability of wave activities was observed with both wind amplitudes growing up to approximately 40 m/s at 95-100 km in day 339 and then decreasing dramatically in day 340. We also found that the sodium density wave perturbation is correlated in phase with temperature perturbation below 90 km, and approximately 180 deg out of phase above. Applying the linear wave theory, we estimated the wave horizontal propagation direction, horizontal wavelength, and apparent horizontal phase speed to be approximately 25 deg south of west, approximately 1800 +/- 150 km, and approximately 28 +/- 2 m/s, respectively of wave intrinsic period, intrinsic phase speed, and vertical wavelength were also estimated. While the onset of enhanced inertia-gravity wave amplitude in the night of 338 was observed to be in coincidence with short-period gravity wave breaking via convective instability, the decrease of inertia-gravity wave amplitude after noon of day 339 was also observed to coincide with the development of atmospheric dynamical instability layers with downward phase progression clearly correlated with the 18-hour inertia-gravity wave, suggesting likely breaking of this inertia-gravity wave via dynamical (shear) instability.

  8. SAS-2 observations of the diffuse gamma radiation in the galactic latitude interval 10 deg absolute b or equal to 90 deg

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Hartman, R. C.; Kniffen, D. A.; Thompson, D. J.; Oegelman, H. B.; Oezel, M. E.; Tuemer, T.

    1977-01-01

    An analysis of all of the second small astronomy satellite gamma-ray data for galactic latitudes with the absolute value of b 10 deg has shown that the intensity varies with galactic latitude, being larger near 10 deg than 90 deg. For energies above 100 MeV the gamma-ray data are consistent with a latitude distribution of the form I(b) = C sub 1 + C sub 2/sin b, with the second term being dominant. This result suggests that the radiation above 100 MeV is coming largely from local regions of the galactic disk. Between 35 and 100 MeV, a similar equation is also a good representation of the data, but here the two terms are comparable. These results indicate that the diffuse radiation above 35 MeV consists of two parts, one with a relatively hard galactic component and the other an isotropic, steep spectral component which extrapolates back well to the low energy diffuse radiation. The steepness of the diffuse isotropic component places significant constraints on possible theoretical models of this radiation.

  9. Turbulent Vortex-Flow Simulation Over a 65 deg Sharp and Blunt Leading-Edge Delta Wing at Subsonic Speeds

    NASA Technical Reports Server (NTRS)

    Ghaffari, Farhad

    2005-01-01

    Turbulent thin-layer, Reynolds-Averaged Navier-Stokes solutions, based on a multi-block structured grid, are presented for a 65 deg delta wing having either a sharp leading edge (SLE) or blunt leading edge (BLE) geometry. The primary objective of the study is to assess the prediction capability of the method for simulating the leading-edge flow separation and the ensuing vortex flow characteristics. Computational results are obtained for two angles of attack of approximately 13 and 20 deg, at free-stream Mach number of 0.40 and Reynolds number of 6 million based on the wing mean aerodynamic chord. The effects of two turbulence models of Baldwin-Lomax with Degani-Schiff (BL/DS) and the Spalart-Allmaras (SA) on the numerical results are also discussed. The computations also explore the effects of two numerical flux-splitting schemes, i.e., flux difference splitting (fds) and flux vector splitting (fvs), on the solution development and convergence characteristics. The resulting trends in solution sensitivity to grid resolution for the selected leading-edge geometries, angles of attack, turbulence models and flux splitting schemes are also presented. The validity of the numerical results is evaluated against a unique set of experimental wind-tunnel data that was obtained in the National Transonic Facility at the NASA Langley Research Center.

  10. Caenorhabditis elegans paraoxonase-like proteins control the functional expression of DEG/ENaC mechanosensory proteins

    PubMed Central

    Chen, Yushu; Bharill, Shashank; Altun, Zeynep; O’Hagan, Robert; Coblitz, Brian; Isacoff, Ehud Y.; Chalfie, Martin

    2016-01-01

    Caenorhabditis elegans senses gentle touch via a mechanotransduction channel formed from the DEG/ENaC proteins MEC-4 and MEC-10. An additional protein, the paraoxonase-like protein MEC-6, is essential for transduction, and previous work suggested that MEC-6 was part of the transduction complex. We found that MEC-6 and a similar protein, POML-1, reside primarily in the endoplasmic reticulum and do not colocalize with MEC-4 on the plasma membrane in vivo. As with MEC-6, POML-1 is needed for touch sensitivity, the neurodegeneration caused by the mec-4(d) mutation, and the expression and distribution of MEC-4 in vivo. Both proteins are likely needed for the proper folding or assembly of MEC-4 channels in vivo as measured by FRET. MEC-6 detectably increases the rate of MEC-4 accumulation on the Xenopus oocyte plasma membrane. These results suggest that MEC-6 and POML-1 interact with MEC-4 to facilitate expression and localization of MEC-4 on the cell surface. Thus MEC-6 and POML-1 act more like chaperones for MEC-4 than channel components. PMID:26941331

  11. Caenorhabditis elegans paraoxonase-like proteins control the functional expression of DEG/ENaC mechanosensory proteins.

    PubMed

    Chen, Yushu; Bharill, Shashank; Altun, Zeynep; O'Hagan, Robert; Coblitz, Brian; Isacoff, Ehud Y; Chalfie, Martin

    2016-04-15

    Caenorhabditis eleganssenses gentle touch via a mechanotransduction channel formed from the DEG/ENaC proteins MEC-4 and MEC-10. An additional protein, the paraoxonase-like protein MEC-6, is essential for transduction, and previous work suggested that MEC-6 was part of the transduction complex. We found that MEC-6 and a similar protein, POML-1, reside primarily in the endoplasmic reticulum and do not colocalize with MEC-4 on the plasma membrane in vivo. As with MEC-6, POML-1 is needed for touch sensitivity, the neurodegeneration caused by themec-4(d)mutation, and the expression and distribution of MEC-4 in vivo. Both proteins are likely needed for the proper folding or assembly of MEC-4 channels in vivo as measured by FRET. MEC-6 detectably increases the rate of MEC-4 accumulation on theXenopusoocyte plasma membrane. These results suggest that MEC-6 and POML-1 interact with MEC-4 to facilitate expression and localization of MEC-4 on the cell surface. Thus MEC-6 and POML-1 act more like chaperones for MEC-4 than channel components. PMID:26941331

  12. Simultaneous X-Ray and Radio Observations of the Unusual Binary LSI + 61 deg 303

    NASA Technical Reports Server (NTRS)

    Harrison, Fiona A.; Leahy, Denis A.; Waltman, Elizabeth

    1996-01-01

    We present simultaneous 0.5 - 10 keV X-ray and two-frequency radio observations at 2.25 and 8.3 GHz of the unusual binary system LSI + 61 deg. 303. This system was observed twice in a single binary orbit by the ASCA satellite, and monitored daily at two radio frequencies during the same orbital cycle with the Greenbank Interferometer. During the first ASCA observation the source was detected with a 1 - 10 keV luminosity 3.6 x 10(exp 33) (d/2.0 kpc)(exp 2) erg 1/s and during the second at a similar level with evidence for a decrease in average flux of 30%. During the first pointing the radio source was at a quiescent 8 GHz flux level of 30 mJy while during the second the radio flux was rising dramatically with an average value of 100 mJy. No variability is seen in the X-ray flux during the first pointing, but during the second the flux is variable by approx. 50% on timescales of approx. 30 minutes. No pulsations are seen in either X-ray observation with an upper limit on pulsed flux of 20%. The low X-ray luminosity and lack of observed pulsations indicate that accretion onto a neutron star surface is not the origin for the high-energy emission. Rather, the X-rays must result either from accreted matter which is stopped at the magnetosphere because the magnetospheric boundry is rotating at super-Keplerian rates or due to a shock formed in the interaction of the dense wind of the Be star companion and a moderately young pulsar. We derive a required pulsar spin down luminosity of approx. 10(exp 37) erg 1/s, and argue that the shock model more easily explains the observed X-ray radio observations.

  13. Local heat/mass transfer distribution around sharp 180 deg turn in a smooth square channel

    NASA Astrophysics Data System (ADS)

    Han, J. C.; Chandra, P. R.; Lau, S. C.

    The naphthalene sublimation technique is used to determine the heat transfer characteristics of turbulent flow in a three-pass square channel whose segments are connected by two sharp 180-deg turns resembling the internal cooling passages of gas turbine blades and vanes. The results obtained show that spanwise-averaged heat transfer initially decreased with increasing distance from the channel entrance, and then sharply increased upon entering the 180-deg turn; the maximum value is attained toward the turn's end. There exist both a low heat transfer region near the inner wall and a region of high heat transfer near the outer wall. For the three Reynolds numbers investigated, local heat transfer coefficients at the 180-deg turn were 2-3 times higher than the fully developed values.

  14. Ten Deg Off-Axis Test for Shear Properties in Fiber Composites

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Sinclair, J. H.

    1977-01-01

    A combined theoretical and experimental investigation was conducted to assess the suitability of the 10 deg off-axis tensile test specimen for the intralaminar shear characterization of unidirectional composites. Composite mechanics, a combined-stress failure criterion, and a finite variation across the specimen width and the relative stress and strain magnitudes at the 10 deg plane. Strain gages were used to measure the strain variation across the specimen width at specimen midlength and near the end tabs. Specimens from Mod-I/epoxy, T-300/epoxy, and S-glass/epoxy were used in the experimental program. It was found that the 10 deg off-axis tensile test specimen is suitable for intralaminar shear characterization, and it is recommended that it should be considered as a possible standard test specimen for such a characterization.

  15. 10-deg off-axis test for shear properties in fiber composites

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Sinclair, J. H.

    1977-01-01

    A combined theoretical and experimental investigation was conducted to assess the suitability of the 10-deg off-axis tensile test specimen for the intralaminar shear characterization of unidirectional composites. Composite mechanics, a combined-stress failure criterion, and a finite-element analysis were used to determine theoretically the stress-strain variation across the specimen width and the relative stress and strain magnitudes at the 10-deg plane. Strain gages were employed to measure the strain variation across the specimen width at specimen midlength and near the end tabs. Specimens from Mod-I/epoxy, T-300/epoxy, and S-glass/epoxy were used in the experimental program. It was found that the 10-deg off-axis tensile test specimen is suitable for intralaminar shear characterization, and it is recommended that it should be considered as a possible standard test specimen for such a characterization.

  16. Ten deg off-axis tensile test for intralaminar shear characterization of fiber composites

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Sinclair, J. H.

    1976-01-01

    A combined theoretical and experimental investigation was conducted to assess the suitability of the 10 deg off-axis tensile test specimen for the intralaminar shear characterization of unidirectional composites. Composite mechanics, a combined-stress failure criterion, and a finite element analysis were used to determine theoretically the stress-strain variation across the specimen width and the relative stress and strain magnitudes at the 10 deg plane. Strain gages were used to measure the strain variation across the specimen width at specimen midlength and near the end tabs. Specimens from Mod-I/epoxy, T-300/epoxy, and S-glass/epoxy were used in the experimental program. It was found that the 10 deg off-axis tensile test specimen is suitable for intralaminar shear characterization and it is recommended that it should be considered as a possible standard test specimen for such a characterization.

  17. Stability of succinylcholine chloride injection at ambient temperature and 4 deg C in polypropylene syringes.

    PubMed

    Storms, Meredith L; Stewart, James T; Warren, Flynn W

    2003-01-01

    The stability of 20-mg/mL succinylcholine chloride injection in 12-mL polypropylene syringes stored at ambient temperature and 4 deg C for up to 90 days was investigated. Concentration levels of succinylcholine chloride injection were determined at 0, 1, 4, 7, 15, 30, 45, 60, and 90 days after preparation of the syringes by means of a high-performance liquid chromatographic stability-indicating assay. Methylparaben, which was added as a preservative, did not interfere with the assay. The loss in potency was less than 10% after 45 days of storage at 25 deg C and less than 1% after 90 days of storage at 4 deg C. The pH of succinylcholine chloride injection did not change appreciably during the 90-day study period. PMID:23979509

  18. Exploratory Investigation of Transpiration Cooling of a 40 deg Double Wedge using Nitrogen and Helium as Coolants at Stagnation Temperatures from 1,295 deg F to 2,910 deg F

    NASA Technical Reports Server (NTRS)

    Rashis, Bernard

    1961-01-01

    An investigation of transpiration cooling has been conducted in the preflight jet of the Langley Pilotless Aircraft Research Station at Wallops Island, Va. The model consisted of a double wedge of 40 deg included angle having a porous stainless-steel specimen inserted flush with the top surface of the wedge. The tests were conducted at a free-stream Mach number of 2.0 for stagnation temperatures ranging from 1,295 F to 2,910 F. Nitrogen and helium were used as coolants and tests were conducted for values ranging from approximately 0.03 to 0.30 percent of the local weight flow rate. The data for both the nitrogen and helium coolants indicated greater cooling effectiveness than that predicted by theory and were in good agreement with the results for an 8 deg cone tested at a stagnation temperature of 600 F. The results indicate that the helium coolant, for the same amount of heat-transfer reduction, requires only about one-fourth to one-fifth the coolant flow weight as the nitrogen coolant.

  19. A Schottky/2-DEG varactor diode for millimeter and submillimeter wave multiplier applications

    NASA Technical Reports Server (NTRS)

    Peatman, W. C. B.; Crowe, Thomas W.; Shur, M.; Gelmont, B.

    1992-01-01

    A new Schottky diode is investigated for use as a multiplier element in the millimeter and submillimeter wavelength regions. The new diode is based on the Schottky contact at the edge of a 2-dimensional electron gas (2-DEG). As a negative voltage is applied to the Schottky contact, the depletion layer between the Schottky contact and the 2-DEG expands and the junction capacitance decreases, resulting in a nonlinear capacitance-voltage characteristic. In this paper, we outline the theory, design, fabrication, and evaluation of the new device. Recent results include devices having cutoff frequencies of 1 THz and above. Preliminary multiplier results are also presented.

  20. 360  deg full-parallax light-field display using panoramic camera.

    PubMed

    Su, Chen; Zhou, Xinxin; Li, Haifeng; Yang, Qing; Wang, Zhechao; Liu, Xu

    2016-06-10

    One of the common approaches to achieving vertical parallax for the horizontal-parallax-only light-field display is to introduce the viewer-tracking method. A panoramic camera is assembled in a 360 deg scanning light-field display system for the full-parallax demand in this study, wherein the image generation algorithm is improved to be sensitive to multiple viewer positions, and the tracking and rendering are processed in real time. The horizontal-parallax-only light-field display using a panoramic camera is determined to be able to achieve smooth and consecutive full-parallax performance for multiple viewers in a 360 deg range. PMID:27409032

  1. On the nature of BD-10 deg 4662. [variable binary star

    NASA Technical Reports Server (NTRS)

    Zappala, R. R.

    1974-01-01

    Attention was first called to BD-10 deg 4662 (now assigned variable-star designation FK Ser) by Stienon (1971), who reported a temporary brightening in the blue on a Case objective-prism plate, accompanied by Balmer emission and a strong ultraviolet continuum. In its normal state the star appeared to be an ordinary late K-type object without emission features. Infrared observations show that BD-10 deg 4662 has excesses in the H - K and K - L colors similar to ordinary T Tauri stars. Emission at Ca II H and K confirms the close relationship to that group of objects.

  2. Impingement of Water Droplets on NACA 65A004 Airfoil at 8 deg Angle of Attack

    NASA Technical Reports Server (NTRS)

    Brun, R. J.; Gallagher, H. M.; Vogt, D. E.

    1954-01-01

    The trajectories of droplets in the air flowing past an NACA 65AO04 airfoil at an angle of attack of 8 deg were determined.. The amount of water in droplet form impinging on the airfoil, the area of droplet impingement, and the rate of droplet impingement per unit area on the airfoil surface were calculated from the trajectories and presented to cover a large range of flight and atmospheric conditions. These impingement characteristics are compared briefly with those previously reported for the same airfoil at an angle of attack of 4 deg.

  3. AC-magnetotransport of a 2DEG in the quantum Hall regime

    SciTech Connect

    Hernández, C.; Chaubet, C.

    2014-05-15

    In this paper we present an ac-magneto-transport study of a two-dimensional electron gas (2DEG) in the quantum Hall effect (QHE) regime, for frequencies in the range [100Hz, 1MHz]. We present a new approach to understand admittance measurements based in the Landauer-Buttiker formalism for QHE edge channels and taking into account the capacitance and the topology of the cables connected to the contacts used in the measurements. Our model predicts an universal behavior with the a-dimensional parameter RCω where R is the 2 wires resistance of the 2DEG, C the capacitance cables and the angular frequency, in agreement with experiments.

  4. Preliminary Investigation of Cyclic Behavior at SHADOZ Sites Between the Equator and 5 deg S Latitude

    NASA Technical Reports Server (NTRS)

    Schmidlin, F. J.

    2009-01-01

    Investigation of cyclic behavior of temperature and ozone data from five SHADOZ sites between the Equator and 5degS Latitude (Nairobi, Ascension Island, Natal, San Crystobal, and Watukoset) reveal an amazing array of oscillations. In particular, eight years of measurements (1998-2007) reveal changes such as decreasing amounts of ozone at some pressure levels and/or sites, while other levels and/or sites experience increasing ozone. Temperature changes of 1-2 C occur that also experience irregular oscillations. This study is preliminary and only concentrates on the 250-, 200-, 100-, 70-, and 50-hPa pressure surfaces. Surfaces existing below and above the tropopause behave differently.

  5. Characterization of DegQVh, a Serine Protease and a Protective Immunogen from a Pathogenic Vibrio harveyi Strain▿ †

    PubMed Central

    Zhang, Wei-wei; Sun, Kun; Cheng, Shuang; Sun, Li

    2008-01-01

    Vibrio harveyi is an important marine pathogen that can infect a number of aquaculture species. V. harveyi degQ (degQVh), the gene encoding a DegQ homologue, was cloned from T4, a pathogenic V. harveyi strain isolated from diseased fish. DegQVh was closely related to the HtrA family members identified in other Vibrio species and could complement the temperature-sensitive phenotype of an Escherichia coli strain defective in degP. Expression of degQVh in T4 was modulated by temperature, possibly through the σE-like factor. Enzymatic analyses demonstrated that the recombinant DegQVh protein expressed in and purified from E. coli was an active serine protease whose activity required the integrity of the catalytic site and the PDZ domains. The optimal temperature and pH of the recombinant DegQVh protein were 50°C and pH 8.0. A vaccination study indicated that the purified recombinant DegQVh was a protective immunogen that could confer protection upon fish against infection by V. harveyi. In order to improve the efficiency of DegQVh as a vaccine, a genetic construct in the form of the plasmid pAQ1 was built, in which the DNA encoding the processed DegQVh protein was fused with the DNA encoding the secretion region of AgaV, an extracellular β-agarase. The E. coli strain harboring pAQ1 could express and secrete the chimeric DegQVh protein into the culture supernatant. Vaccination of fish with viable E. coli expressing chimeric degQVh significantly (P < 0.001) enhanced the survival of fish against V. harveyi challenge, which was possibly due to the relatively prolonged exposure of the immune system to the recombinant antigen produced constitutively, albeit at a gradually decreasing level, by the carrier strain. PMID:18723647

  6. Rotary balance data and analysis for the X-29A airplane for an angle-of-attack range of 0 deg to 90 deg

    NASA Technical Reports Server (NTRS)

    Ralston, J. N.

    1984-01-01

    The rotational aerodynamic characteristics are discussed for a 1/8 scale model of the X-29A airplane. The effects of rotation on the aerodynamics of the basic model were determined, as well as the influence of airplane components, various control deflections, and several forebody modifications. These data were measured using a rotary balance, over an angle of attack range of 0 to 90 deg, for clockwise and counter clockwise rotations covering an omega b/2V range of 0 to 0.4.

  7. Rotary balance data for an F-15 model with conformal fuel tanks for an angle-of-attack range of 8 deg to 90 deg

    NASA Technical Reports Server (NTRS)

    Barnhart, B.

    1982-01-01

    Aerodynamic characteristics obtained in a rotational flow environment, utilizing a rotary balance, are presented in plotted form for a 1/12 scale conformal fuel tank equipped F-15 airplane model. The configurations tested included in the buildup of airplane components and the basic airplane with various control deflections. Data are presented for all configurations without analysis for an angle of attack range of 8 to 90 deg, and clockwise and counterclockwise rotations covering an omega b/2V range from 0 to 0.4. Selected configurations are presented over an extended omega b/2V range from 0 to 0.9.

  8. The 1985 chlorine and fluorine inventories in the stratosphere based on ATMOS observations at 30 deg North latitude

    NASA Technical Reports Server (NTRS)

    Zander, R.; Gunson, M. R.; Farmer, C. B.; Rinsland, C. P.; Irion, F. W.; Mahieu, E.

    1992-01-01

    Results are presented of an investigation of the Cl and F inventories derived from the concentrations of eleven Cl- and F-bearing organic and inorganic species throughout the atmosphere, based on observations with the Atmospheric Trace Molecule Spectroscopy instrument aboard the Space Shuttle during the Spacelab 3 mission of April 29 to May 6, 1985. It was found that, in April-May 1985, near 30 deg N, the mean total stratospheric concentrations of Cl and F were 2.58 +/-0.10 ppbv and 1.15 +/-0.12 ppbv, respectively. Partitioning among the source, sink, and reservoir species was consistent with the conservation of the F and Cl budgets throughout the stratosphere. It is shown that the budgets of Cl and F above about 45 km altitude can be determined accurately by measuring only HCl, HF, and CF4 and provide a straightforward timely reference point for future inventories and trends evaluations.

  9. Experimental Investigation of the Flow about a 65 deg Delta Wing in the NASA Langley National Transonic Facility. Chapter 4

    NASA Technical Reports Server (NTRS)

    Luckring, James M.

    2009-01-01

    An experimental investigation for the flow about a 65 deg. delta wing has been conducted in the NASA Langley National Transonic Facility (NTF). The tests were conducted at Reynolds numbers, based on the mean aerodynamic chord, ranging from 6 million to 120 million and at Mach numbers ranging from 0.4 to 0.9. The model incorporated four different leading-edge bluntness values. The data include detailed static surfacepressure distributions as well as normal-force and pitching-moment coefficients. The test program was designed to quantify the effects of Mach number, Reynolds number, and leading-edge bluntness on the onset and progression of leading-edge vortex separation.

  10. 'Candidatus Phytoplasma sudamericanum' a novel taxon from diseased passion fruit (Passiflora edulis f. flavicarpa Deg.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Symptoms of abnormal proliferation of shoots resulting in formation of witches’ broom growths were observed in diseased plants of passion fruit (Passiflora edulis f. flavicarpa Deg.) in Brazil. RFLP analysis of 16S rRNA gene sequences amplified in polymerase chain reactions containing template DNAs...

  11. Exploring a possible origin of a 14 deg y-normal spin tilt at RHIC polarimeter

    SciTech Connect

    Meot, F.; Huang, H.

    2015-06-15

    A possible origin of a 14 deg y-normal spin n0 tilt at the polarimeter is in snake angle defects. This possible cause is investigated by scanning the snake axis angle µ, and the spin rotation angle at the snake, φ, in the vicinity of their nominal values.

  12. Mapping algorithm for 360-deg profilometry with time delayed integration imaging

    NASA Astrophysics Data System (ADS)

    Asundi, Anand K.; Zhou, Wensen

    1999-02-01

    A direct phase-to-radial distance mapping algorithm for 360 deg profilometry with time delay and integration imaging is presented. This method, based on an inherent mapping relationship, is capable of speedy and accurate measurement without the determination of any geometric parameter. The capability of the mapping algorithm is demonstrated by measuring a plane and a shoe.

  13. Two-year moored instrument results along 152 deg E. [of North Pacific

    NASA Technical Reports Server (NTRS)

    Schmitz, William J., Jr.; Niiler, Pearn P.; Koblinsky, Chester J.

    1987-01-01

    Results from a 2-year (nominal) deployment of a moored array along 152 deg E from 28 deg N to 41 deg N are presented, with emphasis on similarities and differences between settings (approximately year-to-year). Ten moorings and 38 instruments were involved, from the fall of 1980 to 1982. Current-temperature meters spanned the water column from 500- to 4000-m depths, with occasional instruments in the vicinity of 300 m and near the bottom (about 6000 m). Upper level features located in the center of the array near 35-36 deg N were generally stable relative to the axis of the Kuroshio Extension, varying from deployment to deployment with meanders in this flow regime. Some properties of the abyssal (about 4000 m) currents were comparatively more variable, with these changes not connected to meandering of the Kuroshio Extension in an obvious way. The vertical structure and frequency distributions of eddy kinetic energy were similar in shape and to some extent in amplitude from deployment to deployment, especially relative to meanders of the Kuroshio Extension, but translated in the opposite direction.

  14. AromaDeg, a novel database for phylogenomics of aerobic bacterial degradation of aromatics

    PubMed Central

    Duarte, Márcia; Jauregui, Ruy; Vilchez-Vargas, Ramiro; Junca, Howard; Pieper, Dietmar H.

    2014-01-01

    Understanding prokaryotic transformation of recalcitrant pollutants and the in-situ metabolic nets require the integration of massive amounts of biological data. Decades of biochemical studies together with novel next-generation sequencing data have exponentially increased information on aerobic aromatic degradation pathways. However, the majority of protein sequences in public databases have not been experimentally characterized and homology-based methods are still the most routinely used approach to assign protein function, allowing the propagation of misannotations. AromaDeg is a web-based resource targeting aerobic degradation of aromatics that comprises recently updated (September 2013) and manually curated databases constructed based on a phylogenomic approach. Grounded in phylogenetic analyses of protein sequences of key catabolic protein families and of proteins of documented function, AromaDeg allows query and data mining of novel genomic, metagenomic or metatranscriptomic data sets. Essentially, each query sequence that match a given protein family of AromaDeg is associated to a specific cluster of a given phylogenetic tree and further function annotation and/or substrate specificity may be inferred from the neighboring cluster members with experimentally validated function. This allows a detailed characterization of individual protein superfamilies as well as high-throughput functional classifications. Thus, AromaDeg addresses the deficiencies of homology-based protein function prediction, combining phylogenetic tree construction and integration of experimental data to obtain more accurate annotations of new biological data related to aerobic aromatic biodegradation pathways. We pursue in future the expansion of AromaDeg to other enzyme families involved in aromatic degradation and its regular update. Database URL: http://aromadeg.siona.helmholtz-hzi.de PMID:25468931

  15. DegS and RseP Homologous Proteases Are Involved in Singlet Oxygen Dependent Activation of RpoE in Rhodobacter sphaeroides

    PubMed Central

    Nuss, Aaron M.; Adnan, Fazal; Weber, Lennart; Berghoff, Bork A.; Glaeser, Jens; Klug, Gabriele

    2013-01-01

    Singlet oxygen (1O2) is the main agent of photooxidative stress and is generated by photosensitizers as (bacterio)chlorophylls. It leads to the damage of cellular macromolecules and therefore photosynthetic organisms have to mount an adaptive response to 1O2 formation. A major player of the photooxidative stress response in Rhodobacter sphaeroides is the alternative sigma factor RpoE, which is inactivated under non-stress conditions by its cognate anti-sigma factor ChrR. By using random mutagenesis we identified RSP_1090 to be required for full activation of the RpoE response under 1O2 stress, but not under organic peroxide stress. In this study we show that both RSP_1090 and RSP_1091 are required for full resistance towards 1O2. Moreover, we revealed that the DegS and RseP homologs RSP_3242 and RSP_2710 contribute to 1O2 resistance and promote ChrR proteolysis. The RpoE signaling pathway in R. sphaeroides is therefore highly similar to that of Escherichia coli, although very different anti-sigma factors control RpoE activity. Based on the acquired results, the current model for RpoE activation in response to 1O2 exposure in R. sphaeroides was extended. PMID:24223961

  16. Evidence of a major fault zone along the California-Nevada state line 35 deg 30 min to 36 deg 30 min north latitude

    NASA Technical Reports Server (NTRS)

    Liggett, M. A.; Childs, J. F.

    1973-01-01

    The author has identified the following significant results. Geologic reconnaissance guided by analysis of ERTS-1 and Apollo-9 satellite imagery and intermediate scale photography from X-15 and U-2 aircraft has confirmed the presence of a major fault zone along the California-Nevada state line, between 35 deg 30 min and 36 deg 30 min north latitude. The name Pahrump Fault Zone has been suggested for this feature after the valley in which it is best exposed. Field reconnaissance has indicated the existence of previously unreported faults cutting bedrock along range fronts, and displacing Tertiary and Quaternary basin sediments. Gravity data support the interpretation of regional structural discontinuity along this zone. Individual fault traces within the Pahrump Fault Zone form generally left-stepping en echelon patterns. These fault patterns, the apparent offset of a Laramide age thrust fault, and possible drag folding along a major fault break suggest a component of right lateral displacement. The trend and postulated movement of the Pahrump Fault Zone are similar to the adjacent Las Vegas Shear Zone and Death Valley-Furnace Creek Faults, which are parts of a regional strike slip system in the southern Basin-Range Province.

  17. Prediction of static aerodynamic characteristics for space-shuttle-like and other bodies at angles of attack from 0 deg to 180 deg

    NASA Technical Reports Server (NTRS)

    Jorgensen, L. H.

    1973-01-01

    An engineering-type procedure is presented for computing normal-force, axial-force, and pitching-moment coefficients for bodies at angles of attack from 0 deg to 180 deg. The procedure is ideally suited for estimating the aerodynamic characteristics of space shuttle booster-like bodies because of the wide range of angles of attack, Mach numbers, and Reynolds numbers to be encountered. The analytical formulas, plots, and references given are also applicable for shuttle orbiter, missile, and aircraft-like bodies of both circular and noncircular cross section. The method for computing normal-force and pitching-moment coefficients is based upon the original proposal of Allen that the crossflow or lift distribution over a body can be expressed as the sum of slender-body potential term and an empirical viscous crossflow term. Although experimental data from which to verify the procedure at very high angles of attack are extremely limited, the comparisons made thus far of computed with experimental results are good. In this report the procedure has been shown to be capable of predicting reasonably well the experimental variation of C sub N, C sub A, C sub m, and x sub ac/l with angle of attack for nine bodies of revolution at a free-stream Mach number of 2.86.

  18. The effect of high curing temperature on the reaction kinetics in MK/lime and MK-blended cement matrices at 60 deg. C

    SciTech Connect

    Rojas, Moises Frias; Sanchez de Rojas, M.I

    2003-05-01

    It is well known that the pozzolanic reaction between metakaolin (MK) and calcium hydroxide produces CSH, C{sub 2}ASH{sub 8} (stratlingite), C{sub 4}AH{sub 13} and C{sub 3}ASH{sub 6} (hydrogarnet). However, the presence or absence of these hydrated phases depends on different parameters, such as curing temperature, matrix used, etc. This paper shows the results of a study in order to know the effect of high curing temperature (60 deg. C) on the kinetics of the pozzolanic reaction in different matrices. MK/lime (calcium hydroxide) and MK-blended cement matrices were studied in samples stored and cured at 60 deg. C and up to 123 days of hydration. The nature, sequence and crystallinity of the hydrated phases were analysed using differential thermal analysis (DTA) and X-ray diffraction (XRD) techniques. Results showed that the sequence and formation of the hydrated phases was different in both matrices cured at 60 deg. C. In an MK/lime matrix, C{sub 2}ASH{sub 8}, C{sub 4}AH{sub 13} and C{sub 3}ASH{sub 6} were the main hydrated phases; while in an MK-blended cement, stratlingite was the sole hydrated phase issued from pozzolanic reaction. The DTA and XRD data also reveal an important fact: there is no evidence of the presence of hydrogarnet in blended cements.

  19. Effects of roughness size on the position of boundary-layer transition and on the aerodynamic characteristics of a 55 deg. swept delta wing at supersonic speeds

    NASA Technical Reports Server (NTRS)

    Stallings, R. L., Jr.; Lamb, M.

    1977-01-01

    An experimental investigation was conducted to determine the effects of roughness size on the position of boundary layer transition and on the aerodynamic characteristics of a 55 deg swept delta wing model. Results are presented and discussed for wind tunnel tests conducted at free stream Mach numbers from 1.50 to 4.63, Reynolds numbers per meter from 3,300,000 to 1.6 x 10 to the 7th power, angles of attack from -8 to 16 deg, and roughness sizes ranging from 0.027 cm sand grit to 0.127 cm high cylinders. Comparisons were made with existing flat plate data. An approximate method was derived for predicting the drag of roughness elements used in boundary layer trips.

  20. Experimental Surface Pressure Data Obtained on 65 deg Delta Wing Across Reynolds Number and Mach Number Ranges. Vol. 3: Medium-radius leading edge

    NASA Technical Reports Server (NTRS)

    Chu, Julio; Luckring, James M.

    1996-01-01

    An experimental wind tunnel test of a 65 deg delta wing model with interchangeable leading edges was conducted in the Langley National Transonic Facility (NTF). The objective was to investigate the effects of Reynolds and Mach numbers on slender-wing leading-edge vortex flows with four values of wing leading-edge bluntness. Experimentally obtained pressure data are presented without analysis in tabulated and graphical formats across a Reynolds number range of 6 x 10(exp 6) to 120 x 10(exp 6) at a Mach number of 0.85 and across a Mach number range of 0.4 to 0.9 at Reynolds numbers of 6 x 10(exp 6), 60 x 10(exp 6), and 120 x 10(exp 6). Normal-force and pitching-moment coefficient plots for these Reynolds number and Mach number ranges are also presented.

  1. Free-Flight Skin-Temperature and Surface-Pressure Measurements on a Highly Polished Nose Having a 100 deg Total-Angle Cone and a 10 deg Half-Angle Conical Flare Section up to a Mach Number of 4.08

    NASA Technical Reports Server (NTRS)

    Rashis, Bernard; Bond, Aleck C.

    1961-01-01

    The skin temperature and surface pressure were measured on a large-scale, highly polished nose having a relatively sharp-tipped 100 deg total-angle cone followed by a conical flare section of 10 deg half-angle. The measurements were obtained in flight from a rocket-propelled model up to a peak Mach number of 4.08 and a peak Reynolds number of 22 x 10(exp 6) per foot. Temperature distributions indicated that the heating on the forward 3.5 inches of the 100 deg cone was lower than the heating on the rearward portion. Likewise, measured temperatures on the flare portion of the test nose were generally lower than the temperatures on the 100 deg cone portion. The data indicated that the local Reynolds numbers of transition, based on calculated boundary-layer momentum thicknesses, ranged from 530 to 940 for a Mach number range from 2.72 to 3.75. Comparison of measured cone pressures with theory for a sharp cone showed that theory overestimates the cone pressures. Pressure measurements on the flare portion of the nose showed that in the lower speed range the flow expands below atmospheric pressure in going from the cone to the flare; however, as the speed increased, the expansion diminished and for speeds greater than a Mach number of approximately 3.0 the flare pressure coefficients were at or near a value of zero.

  2. Thermal stability of 2DEG at amorphous LaAlO3/crystalline SrTiO3 heterointerfaces

    NASA Astrophysics Data System (ADS)

    Moon, Seon Young; Moon, Cheon Woo; Chang, Hye Jung; Kim, Taemin; Kang, Chong-Yun; Choi, Heon-Jin; Kim, Jin-Sang; Baek, Seung-Hyub; Jang, Ho Won

    2016-04-01

    At present, the generation of heterostructures with two dimensional electron gas (2DEG) in amorphous LaAlO3 (a-LAO)/SrTiO3 (STO) has been achieved. Herein, we analysed thermal stability of 2DEG at a-LAO/STO interfaces in comparison with 2DEG at crystalline LaAlO3 (c-LAO)/STO interfaces. To create 2DEG at LAO/STO interface, regardless of growing temperature from 25 to 700 °C, we found that environment with oxygen deficient during the deposition of LAO overlayer is essentially required. That indicates that the oxygen-poor condition in the system is more essential than the crystalline nature of LAO layer. 2DEG at a-LAO/STO interface is depleted upon ex situ annealing at 300 °C under 300 Torr of oxygen pressure, while that in c-LAO/STO interface is still maintained. Our result suggests that the LAO overlayer crystallinity critically affects the thermal-annealing-induced depletion of 2DEG at a-LAO/STO interface rather than the generation of 2DEG. We clearly provide that amorphous TiOx can efficiently prevent the thermal degradation of 2DEG at the a-LAO/STO interface, which gives a cornerstone for achieving thermal-stable 2DEG at a-LAO/STO interface.

  3. The Caltech-NRAO Stripe 82 Survey (CNSS). I. The Pilot Radio Transient Survey In 50 deg2

    NASA Astrophysics Data System (ADS)

    Mooley, K. P.; Hallinan, G.; Bourke, S.; Horesh, A.; Myers, S. T.; Frail, D. A.; Kulkarni, S. R.; Levitan, D. B.; Kasliwal, M. M.; Cenko, S. B.; Cao, Y.; Bellm, E.; Laher, R. R.

    2016-02-01

    We have commenced a multiyear program, the Caltech-NRAO Stripe 82 Survey (CNSS), to search for radio transients with the Jansky VLA in the Sloan Digital Sky Survey Stripe 82 region. The CNSS will deliver five epochs over the entire ˜270 deg2 of Stripe 82, an eventual deep combined map with an rms noise of ˜40 μJy and catalogs at a frequency of 3 GHz, and having a spatial resolution of 3″. This first paper presents the results from an initial pilot survey of a 50 deg2 region of Stripe 82, involving four epochs spanning logarithmic timescales between 1 week and 1.5 yr, with the combined map having a median rms noise of 35 μJy. This pilot survey enabled the development of the hardware and software for rapid data processing, as well as transient detection and follow-up, necessary for the full 270 deg2 survey. Data editing, calibration, imaging, source extraction, cataloging, and transient identification were completed in a semi-automated fashion within 6 hr of completion of each epoch of observations, using dedicated computational hardware at the NRAO in Socorro and custom-developed data reduction and transient detection pipelines. Classification of variable and transient sources relied heavily on the wealth of multiwavelength legacy survey data in the Stripe 82 region, supplemented by repeated mapping of the region by the Palomar Transient Factory. A total of {3.9}-0.9+0.5% of the few thousand detected point sources were found to vary by greater than 30%, consistent with similar studies at 1.4 and 5 GHz. Multiwavelength photometric data and light curves suggest that the variability is mostly due to shock-induced flaring in the jets of active galactic nuclei (AGNs). Although this was only a pilot survey, we detected two bona fide transients, associated with an RS CVn binary and a dKe star. Comparison with existing legacy survey data (FIRST, VLA-Stripe 82) revealed additional highly variable and transient sources on timescales between 5 and 20 yr, largely

  4. The warm and cold neutral phase in the local interstellar medium at absolute value of B greater than or equal to 10 deg

    NASA Astrophysics Data System (ADS)

    Poppel, W. G. L.; Marronetti, P.; Benaglia, P.

    1994-07-01

    We made a systematic separation of both the neutral phases using the atlases of 21-cm profiles of Heiles & Habing (1974) and Colomb et al. (1980), complemented with other data. First, we fitted the emission of the warm neutral medium (WNM) by means of a broad Gaussian curve (velocity dispersion sigma approximately 10-14 km/s). We derived maps of the column densities NWH and the radial velocities VW of the WNM. Its overall distribution appears to be very inhomogeneous with a large hole in the range b greater than or equal to +50 deg. However, if the hole is excluded, the mean latitude-profiles admit a rough cosec absolute value of b-fit common to both hemispheres. A kinematical analysis of VW for the range 10 deg less than or equal to absolute value of b less than or equal to 40 deg indicates a mean differential rotation with a small nodal deviation. At absolute value of b greater than 50 deg VW is negative, with larger values and discontinuities in the north. On the mean, sigma increases for absolute value of b decreasing, as is expected from differential rotation. From a statistical study of the peaks of the residual profiles we derived some characteristics of the cold neutral medium (CNM). The latter is generally characterized by a single component of sigma approximately 2-6 km/s. Additionally we derived the sky-distribution of the column densities NCH and the radial velocities VC of the CNM within bins of 1.2 deg sec b x 1 deg in l, b. Furthermore, we focused on the characteristics of Linblad's feature A of cool gas by considering the narrow ridge of local H I, which appears in the b-V contour maps at fixed l (e.g. Schoeber 1976). The ridge appears to be the main component of the CNM. We suggest a scenario for the formulation and evolution of the Gould belt system of stars and gas on the basis of an explosive event within a shingle of cold dense gas tilted to the galactic plane. The scenario appears to be consistent with the results found for both the neutral

  5. Experimental Surface Pressure Data Obtained on 65 deg Delta Wing Across Reynolds Number and Mach Number Ranges. Volume 2; Small-Radius Leading Edge

    NASA Technical Reports Server (NTRS)

    Chu, Julio; Luckring, James M.

    1996-01-01

    An experimental wind tunnel test of a 65 deg. delta wing model with interchangeable leading edges was conducted in the Langley National Transonic Facility (NTF). The objective was to investigate the effects of Reynolds and Mach numbers on slender-wing leading-edge vortex flows with four values of wing leading-edge bluntness. Experimentally obtained pressure data are presented without analysis in tabulated and graphical formats across a Reynolds number range of 6 x 10(exp 6) to 84 x 10(exp 6) at a Mach number of 0.85 and across a Mach number range of 0.4 to 0.9 at Reynolds numbers of 6 x 10(exp 6) and 60 x 10(exp 6). Normal-force and pitching-moment coefficient plots for these Reynolds number and Mach number ranges are also presented.

  6. Experimental Surface Pressure Data Obtained on 65 deg Delta Wing Across Reynolds Number and Mach Number Ranges. Vol. 4: Large-radius leading edge

    NASA Technical Reports Server (NTRS)

    Chu, Julio; Luckring, James M.

    1996-01-01

    An experimental wind tunnel test of a 65 deg delta wing model with interchangeable leading edges was conducted in the Langley National Transonic Facility (NTF). The objective was to investigate the effects of Reynolds and Mach numbers on slender-wing leading-edge vortex flows with four values of wing leading-edge bluntness. Experimentally obtained pressure data are presented without analysis in tabulated and graphical formats across a Reynolds number range of 6 x 10(exp 6) to 120 x 10(exp 6) at a Mach number of 0.85 and across a Mach number range of 0.4 to 0.9 at Reynolds numbers of 6 x 10(exp 6) and 60 x 10(exp 6). Normal-force and pitching-moment coefficient plots for these Reynolds number and Mach number ranges are also presented.

  7. Rehydration and microstructure of cement paste after heating at temperatures up to 300 deg. C

    SciTech Connect

    Farage, M.C.R.; Sercombe, J.; Galle, C

    2003-07-01

    This paper is concerned with the evolution of the microstructure of cementitious materials subjected to high temperatures and subsequent resaturation in the particular context of long-term storage of radioactive wastes, where diffusive and convective properties are of primary importance. Experimental results obtained by mercury intrusion porosimetry (MIP) are presented concerning the evolution of the pore network of ordinary portland cement (OPC) paste heated at temperatures varying between 80 and 300 deg. C. The consequences of heating on the macroscopic properties of cement paste are evaluated by measures of the residual gas permeabilities, elastic moduli and Poisson's ratio, obtained by nondestructive methods. Resaturation by direct water absorption and water vapour sorption are used to estimate the reversibility of dehydration. The results provide some evidence of the self-healing capacity of resaturated cement paste after heating at temperatures up to 300 deg. C.

  8. Ulysses at 50 deg south: Constant immersion in the high-speed solar wind

    NASA Technical Reports Server (NTRS)

    Phillips, J. L.; Balogh, A.; Bame, S. J.; Goldstein, B. E.; Gosling, J. T.; Hoeksema, J. T.; Mccomas, D. J.; Neugebauer, M.; Sheeley, N. R., Jr.; Wang, Y.-M.

    1994-01-01

    We present speed observations from the Ulysses solar wind plasma experiment through 50 deg south latitude. The pronounced speed modulation arising from solar rotation and the tilt of the heliomagnetic current sheet has nearly disappeared. Ulysses is now observing wind speeds in the 700 to 800 km/s range, with a magnetic polarity indicating an origin in the large south polar coronal hole. The strong compressions, rarefractions, and shock waves previously seen have weakened or disappeared. Occasional coronal mass ejections characterized by low plasma density caused by radial expansion have been observed. The coronal configuration was simple and stable in 1993, indicating that the observed solar wind changes were caused by increasing spacecraft latitude. Trends in prevailing speed with increasing latitude support previous findings. A decrease in peak speed southward of 40 deg latitude may indicate that the fastest solar wind comes from the equatorial extensions of the polar coronal holes.

  9. Simulated cosmic microwave background maps at 0.5 deg resolution: Basic results

    NASA Technical Reports Server (NTRS)

    Hinshaw, G.; Bennett, C. L.; Kogut, A.

    1995-01-01

    We have simulated full-sky maps of the cosmic microwave background (CMB) anisotropy expected from cold dark matter (CDM) models at 0.5 deg and 1.0 deg angular resolution. Statistical properties of the maps are presented as a function of sky coverage, angular resolution, and instrument noise, and the implications of these results for observability of the Doppler peak are discussed. The rms fluctuations in a map are not a particularly robust probe of the existence of a Doppler peak; however, a full correlation analysis can provide reasonable sensitivity. We find that sensitivity to the Doppler peak depends primarily on the fraction of sky covered, and only secondarily on the angular resolution and noise level. Color plates of the simulated maps are presented to illustrate the anisotropies.

  10. Characterizing concentrations of diethylene glycol and suspected metabolites in human serum, urine, and cerebrospinal fluid samples from the Panama DEG mass poisoning

    PubMed Central

    SCHIER, J. G.; HUNT, D. R.; PERALA, A.; MCMARTIN, K. E.; BARTELS, M. J.; LEWIS, L. S.; MCGEEHIN, M. A.; FLANDERS, W. D.

    2015-01-01

    Context Diethylene glycol (DEG) mass poisoning is a persistent public health problem. Unfortunately, there are no human biological data on DEG and its suspected metabolites in poisoning. If present and associated with poisoning, the evidence for use of traditional therapies such as fomepizole and/or hemodialysis would be much stronger. Objective To characterize DEG and its metabolites in stored serum, urine, and cerebrospinal fluid (CSF) specimens obtained from human DEG poisoning victims enrolled in a 2006 case-control study. Methods In the 2006 study, biological samples from persons enrolled in a case-control study (42 cases with new-onset, unexplained AKI and 140 age-, sex-, and admission date-matched controls without AKI) were collected and shipped to the Centers for Disease Control and Prevention (CDC) in Atlanta for various analyses and were then frozen in storage. For this study, when sufficient volume of the original specimen remained, the following analytes were quantitatively measured in serum, urine, and CSF: DEG, 2-hydroxyethoxyacetic acid (HEAA), diglycolic acid, ethylene glycol, glycolic acid, and oxalic acid. Analytes were measured using low resolution GC/MS, descriptive statistics calculated and case results compared with controls when appropriate. Specimens were de-identified so previously collected demographic, exposure, and health data were not available. The Wilcoxon Rank Sum test (with exact p-values) and bivariable exact logistic regression were used in SAS v9.2 for data analysis. Results The following samples were analyzed: serum, 20 case, and 20 controls; urine, 11 case and 22 controls; and CSF, 11 samples from 10 cases and no controls. Diglycolic acid was detected in all case serum samples (median, 40.7 mcg/mL; range, 22.6 – 75.2) and no controls, and in all case urine samples (median, 28.7 mcg/mL; range, 14 – 118.4) and only five (23%) controls (median,

  11. Mantle viscosity beneath the Galapagos 95.5 deg W propagating rift

    NASA Technical Reports Server (NTRS)

    Schubert, G.; Hey, R. N.

    1986-01-01

    Detailed geophysical surveys in the vicinity of the Galapagos 95.5 deg W propagating rift tip establish the opening history of the rift and its velocity of propagation. These data together with a theory for mantle upwelling into slowly widening lithospheric cracks constrain the viscosity of the asthenosphere beneath the propagating rift to be less than about 10 to the 17th to 10 to the 18th Pa s.

  12. Leading edge vortex-flap experiments on a 74 deg delta wing

    NASA Technical Reports Server (NTRS)

    Rao, D. M.

    1979-01-01

    Exploratory wind tunnel tests are reported on a 74 deg. delta wing model. The potential of a vortex flap concept in reducing the subsonic lift dependent drag of highly swept, slender wings is examined. The suction effect of coiled vortices generated through controlled separation over leading edge flap surfaces to produce a thrust component is discussed. A series of vortex-flap configurations were investigated to explore the effect of some primary geometric variables.

  13. Fragmentation of N-14 nuclei at 29 GeV - Inclusive isotope spectra at 0 deg.

    NASA Technical Reports Server (NTRS)

    Heckman, H. H.; Greiner, D. E.; Lindstrom, P. J.; Bieser, F. S.

    1972-01-01

    We report the first results of a Bevatron heavy-ion experiment on the inclusive spectra of isotopically identified nuclei 3(Z-range between 3 and 7), produced by the fragmentation of 29-GeV N-14 ions in carbon and hydrogen. The preliminary values of the partial differential cross sections at 0 deg give evidence that the modes of fragmentation of N-14 projectiles are independent of the target nucleus.

  14. Mercury transit at the rotonda of Santa Maria degli Angeli on May 9th 2016

    NASA Astrophysics Data System (ADS)

    Cuevas Cardona, Salvador; Sigismondi, Costantino

    2016-05-01

    Image quality simulations were made for a Mercury image on the solar disc for the sun position on the sky respect the Summer lens of the "Divinità in Luce" glasswork at Santa Maria degli Angeli in Rome. It is shown the image quality of the lens will be enough to show the Mercury shadow on the solar disc but only for the first 30 minutes from the transit's first contact.

  15. Sexy DEG/ENaC channels involved in gustatory detection of fruit fly pheromones.

    PubMed

    Pikielny, Claudio W

    2012-01-01

    Hydrocarbon pheromones on the cuticle of Drosophila melanogaster modulate the complex courtship behavior of males. Recently, three members of the degenerin/epithelial Na+ channel (DEG/ENaC) family of sodium channel subunits, Ppk25, Ppk23, and Ppk29 (also known as Nope), have been shown to function in gustatory perception of courtship-modulating contact pheromones. All three proteins are required for the activation of male courtship by female pheromones. Specific interactions between two of them have been demonstrated in cultured cells, suggesting that, in a subset of cells where they are coexpressed, these three subunits function within a common heterotrimeric DEG/ENaC channel. Such a DEG/ENaC channel may be gated by pheromones, either directly or indirectly, or alternatively may control the excitability of pheromone-sensing cells. In addition, these studies identify taste neurons that respond specifically to courtship-modulating pheromones and mediate their effects on male behavior. Two types of pheromone-sensing taste neurons, F and M cells, have been defined on the basis of their specific response to either female or male pheromones. These reports set the stage for the dissection of the molecular and cellular mechanisms that mediate gustatory detection of contact pheromones. PMID:23131844

  16. A study of the vortex flow over 76/40-deg double-delta wing

    NASA Technical Reports Server (NTRS)

    Verhaagen, N. G.; Jenkins, L. N.; Kern, S. B.; Washburn, A. E.

    1995-01-01

    A low-speed wind-tunnel study of the flow about a 76/40-deg double-delta wing is described for angles of attack ranging from -10 to 25 deg and Reynolds numbers ranging from 0.5 to 1.5 Million. The study was conducted to provide data for the purpose of understanding the vortical flow behavior and for validating Computational Fluid Dynamics methods. Flow visualization tests have provided insight into the effect of the angle of attack and Reynolds number of the vortex-dominated flow both on and off of the surface of the double-delta wing. Upper surface pressure recordings from pressure orifices and Pressure Sensitive Paint have provided data on the pressures induced by the vortices. Flowfield surveys were carried out at an angle of attack of 10 deg by using a thin 5-hole probe. Numerical solutions of the compressible thin-layer Navier-Stokes equations were conducted and compared to the experimental data.

  17. Off-nadir antenna bias correction using Amazon rain forest sigma deg data. [Brazil

    NASA Technical Reports Server (NTRS)

    Birrer, I. J.; Bracalente, E. M.; Dome, G. J.; Sweet, J.; Berthold, G.; Moore, R. K. (Principal Investigator)

    1981-01-01

    The radar response from the Amazon rain forest was studied to determine the suitability of this region for use as a standard target to calibrate a scatterometer like that proposed for the National Ocean Satellite System (NOSS). Backscattering observations made by the SEASAT-1 scatterometer system show the Amazon rain forest to be a homogeneous, azimuthally-isotropic, radar target which is insensitive to polarization. The variation with angle of incidence may be adequately modeled as sigma deg (dB) = alpha theta + beta with typical values for the incidence-angle coefficient from 0.07 dB deg to 0.15 dB/deg. A small diurnal effect occurs, with measurements at sunrise being 0.5 dB to 1 dB higher than the rest of the day. Maximum likelihood estimation algorithms are presented which permit determination of relative bias and true pointing angle for each beam. Specific implementation of these algorithms for the proposed NOSS scatterometer system is also discussed.

  18. Sensory Functions for Degenerin/Epithelial Sodium Channels (DEG/ENaC)

    PubMed Central

    Ben-Shahar, Yehuda

    2012-01-01

    All animals use a sophisticated array of receptor proteins to sense their external and internal environments. Major advances have been made in recent years in understanding the molecular and genetic bases for sensory transduction in diverse modalities, indicating that both metabotropic and ionotropic pathways are important in sensory functions. Here, I review the historical background and recent advances in understanding the roles of a relatively newly discovered family of receptors, the degenerin/epithelial sodium channels (DEG/ENaC). These animal-specific cation channels show a remarkable sequence and functional diversity in different species and seem to exert their functions in diverse sensory modalities. Functions for DEG/ENaC channels have been implicated in mechanosensation as well as chemosensory transduction pathways. In spite of overall sequence diversity, all family members share a unique protein topology that includes just two transmembrane domains and an unusually large and highly structured extracellular domain, that seem to be essential for both their mechanical and chemical sensory functions. This review will discuss many of the recent discoveries and controversies associated with sensory function of DEG/ENaC channels in both vertebrate and invertebrate model systems, covering the role of family members in taste, mechanosensation, and pain. PMID:22099690

  19. Isothermal fatigue behaviour of a (90 deg)8 SiC/Ti-15-3 composite at 426 C

    NASA Technical Reports Server (NTRS)

    Gayda, J.; Gabb, T. P.

    1992-01-01

    The transverse fatigue behavior of a unidirectional SiC/Ti-15-3 composite is characterized at 426 C. The fatigue behavior of this composite along the (0 deg)8 fiber direction and that of unreinforced Ti-15-3 alloy is compared. It is found that the (90 deg)8 composite fatigue life is much shorter than that of the (0 deg)8 composite. The (90 deg)8 fatigue life is much lower than that of the unreinforced Ti-15-3 alloy. Results from 1D model and fractographic evidence for the (90 deg)8 fatigue behavior indicate that the short life of the composite in this orientation is caused by weak fiber-matrix bond strength.

  20. Sea level variabilities in the Gulf Stream between Cape Hatteras and 50 deg W - A Geosat study

    NASA Technical Reports Server (NTRS)

    Vazquez, Jorge; Zlotnicki, Victor; Fu, Lee-Lueng

    1990-01-01

    Sea level variabilities in the Gulf Stream between Cape Hatteras and 50 deg W were examined by studying sea level residuals, relative to a 2-yr mean sea level, obtained from Geosat altimetry data for the period between November 1986 and December 1988. An array of sea-level time series was constructed for a region bounded by 30 deg N and 45 deg N in latitude and by 80 deg W and 50 deg W longitude. It is shown that the spectral characteristics of this time series varies with geographic location along the Gulf Stream path. Concurrent NOAA IR images are used to aid in the interpretation of sea level observations in terms of the variability of the stream's path, demonstrating the synergistic value of the combination of satellite-altimeter and IR data.

  1. Exercise Within LBNP to Produce Artificial Gravity

    NASA Technical Reports Server (NTRS)

    Hargens, Alan R.

    1996-01-01

    Integrated physiologic countermeasures are needed to maintain orthostatic tolerance after spaceflight or bed rest. We hypothesized that supine exercise during LBNP would prevent bed rest-induced loss of orthostatic tolerance by preventing hemoconcentration. In a study conducted jointly with NASA Johnson Space Center and the University of Texas Medical Branch, Galveston, TX, fifteen male subjects underwent 5 days of 6 deg head-down bed rest: 5 control subjects did not exercise, and 10 performed 30 min/day of supine interval treadmill exercise at intensities up to 90% VO(sub 2peak). We will undertake two 14 day bed-rest studies (6 deg head-down tilt bed rest, HDT) to investigate the mechanism of action and efficacy of our partial vacuum exerciser concept. These 14 day bed rest studies were chosen to simulate current microgravity exposures for Space Shuttle crew members.

  2. Effects of antiorthostatic bedrest on the cardiorespiratory responses to exercise

    NASA Technical Reports Server (NTRS)

    Convertino, V. A.; Bisson, R.; Bates, R.; Goldwater, D.; Sandler, H.

    1981-01-01

    The cardiorespiratory changes in exercise performance induced by horizontal and antiorthostatic bed rest are compared in order to determine the physiological changes occurring in the antiorthostatic position and their degree of similarity to those observed in weightlessness. Systolic and diastolic pressures, heart rates, maximum oxygen uptake, ventilation volume during and following 5 min of submaximal exercise in the supine position and body weight and composition were determined in subjects before and following 7 days of bed rest in the horizontal or 6-deg head-down positions. Bed rest is found to result in a general decrease in exercise tolerance as indicated by cardiorespiratory parameters in both groups, with the 6-deg head-down treatment causing greater cardiovascular deconditioning. When compared with space flight data, the antiorthostatic position is shown to simulate the effects of weightlessness more effectively than horizontal bed rest

  3. An Improved Micropropagation Protocol by Ex Vitro Rooting of Passiflora edulis Sims. f. flavicarpa Deg. through Nodal Segment Culture.

    PubMed

    Shekhawat, Mahipal S; Manokari, M; Ravindran, C P

    2015-01-01

    A procedure for rapid clonal propagation of Passiflora edulis Sims. f. flavicarpa Deg. (Passifloraceae) has been developed in this study. Nodal explants were sterilized with 0.1% HgCl2 and inoculated on Murashige and Skoog (MS) basal medium. The addition of 2.0 mgL(-1) 6-benzylaminopurine (BAP) to MS medium caused an extensive proliferation of multiple shoots (8.21 ± 1.13) primordial from the nodal meristems. Subculturing of these multiple shoots on the MS medium augmented with 1.0 mgL(-1) of each BAP and Kinetin (Kin) was successful for the multiplication of the shoots in vitro with maximum numbers of shoots (25.73 ± 0.06) within four weeks of incubation. Shoots were rooted best (7.13 ± 0.56 roots/shoots) on half strength MS medium supplemented with 2.0 mgL(-1) indole-3 butyric acid (IBA). All in vitro regenerated shoots were rooted by ex vitro method, and this has achieved 6-7 roots per shoot by pulsing of cut ends of the shoots using 200 as well as 300 mgL(-1) IBA. The plantlets were hardened in the greenhouse for 4-5 weeks. The hardened plantlets were shifted to manure containing nursery polybags after five weeks and then transferred to a sand bed for another four weeks for acclimatization before field planting with 88% survival rate. PMID:26273489

  4. An Improved Micropropagation Protocol by Ex Vitro Rooting of Passiflora edulis Sims. f. flavicarpa Deg. through Nodal Segment Culture

    PubMed Central

    Shekhawat, Mahipal S.; Manokari, M.; Ravindran, C. P.

    2015-01-01

    A procedure for rapid clonal propagation of Passiflora edulis Sims. f. flavicarpa Deg. (Passifloraceae) has been developed in this study. Nodal explants were sterilized with 0.1% HgCl2 and inoculated on Murashige and Skoog (MS) basal medium. The addition of 2.0 mgL−1 6-benzylaminopurine (BAP) to MS medium caused an extensive proliferation of multiple shoots (8.21 ± 1.13) primordial from the nodal meristems. Subculturing of these multiple shoots on the MS medium augmented with 1.0 mgL−1 of each BAP and Kinetin (Kin) was successful for the multiplication of the shoots in vitro with maximum numbers of shoots (25.73 ± 0.06) within four weeks of incubation. Shoots were rooted best (7.13 ± 0.56 roots/shoots) on half strength MS medium supplemented with 2.0 mgL−1 indole-3 butyric acid (IBA). All in vitro regenerated shoots were rooted by ex vitro method, and this has achieved 6-7 roots per shoot by pulsing of cut ends of the shoots using 200 as well as 300 mgL−1 IBA. The plantlets were hardened in the greenhouse for 4-5 weeks. The hardened plantlets were shifted to manure containing nursery polybags after five weeks and then transferred to a sand bed for another four weeks for acclimatization before field planting with 88% survival rate. PMID:26273489

  5. Changes in leg volume during microgravity simulation

    NASA Technical Reports Server (NTRS)

    Thornton, William E.; Hedge, Vickie; Coleman, Eugene; Uri, John J.; Moore, Thomas P.

    1992-01-01

    Little published information exists regarding the magnitude and time course of cephalad fluid shift resulting from microgravity simulations. Six subjects were exposed to 150 min each at horizontal bed rest, 6-deg head-down tilt, and horizontal water immersion. Fluid shift was estimated by calculating leg volumes from eight serial girth measurements from groin to ankle before, during, and after exposure. Results were compared with data from the first 3 h of spacecraft. By the end of exposure, total leg volume for the six subjects decreased by 2.6 +/- 0.8 percent, 1.7 +/- 1.2 percent, and 4.0 +/- 1.6 percent for horizontal, head-down, and immersion, respectively. Changes had plateaued for horizontal and head-down and had slowed for immersion. Relatively more fluid was lost from the lower leg than the thigh for all three conditions, particularly head-down. During the first 3 h of spaceflight, total leg volume decreased by 8.6 percent, and relatively more fluid was lost from the thigh than the lower leg. The difference in volume changes in microgravity and simulated microgravity may be caused by the small transverse pressures still present in ground-based simulations and the extremely nonlinear compliance of tissue.

  6. MAP determinations of the parallaxes of stars in the regions of HD 2665, BD +68.946 deg, and Lambda Ophiuchi. [Multichannel Astrometric Photometer

    NASA Technical Reports Server (NTRS)

    Gatewood, George

    1989-01-01

    The Multichannel Astrometic Photometer and new optical system of the Allegheny Observatory have been used to obtain parallaxes of stars in the regions of HD 2665, BD +68.946 deg, and Lambda Ophiuchi. HD 2665 is found to have an absolute visual magnitude of 1.6 + or - 0.4 and a distance of 149 + or - 28 pc. It is shown that the Lambda Ophiuchi system has a parallax of 23.5 + or - 2.1 mas and that its A0 V and A4 V components have masses of 2.7 + or - 0.7 and 1.5 + or - 0.4 solar masses, respectively.

  7. Subsonic and transonic pressure distributions around a bluff afterbody in the wake of a 120 deg cone for various separation distances

    NASA Technical Reports Server (NTRS)

    Sawyer, J. W.; Whitcomb, C. F.

    1971-01-01

    A wind-tunnel investigation was conducted at free-stream Mach numbers from 0.20 to 1.00 and Reynolds numbers, based on maximum afterbody diameter, from 2.25 million to 6.90 million on solid models of an attached inflatable decelerator (AID) concept. Tests were conducted to obtain static and ram surface pressure distributions about the basic shapes and at various separation distances between the 120 deg conical forebody and the inflated afterbody shape. The resulting data were used to study the feasibility of extracting a payload from a conical forebody by means of an AID.

  8. High Ca2+ permeability of a peptide-gated DEG/ENaC from Hydra

    PubMed Central

    Dürrnagel, Stefan; Falkenburger, Björn H.

    2012-01-01

    Degenerin/epithelial Na+ channels (DEG/ENaCs) are Na+ channels that are blocked by the diuretic amiloride. In general, they are impermeable for Ca2+ or have a very low permeability for Ca2+. We describe here, however, that a DEG/ENaC from the cnidarian Hydra magnipapillata, the Hydra Na+ channel (HyNaC), is highly permeable for Ca2+ (PCa/PNa = 3.8). HyNaC is directly gated by Hydra neuropeptides, and in Xenopus laevis oocytes expressing HyNaCs, RFamides elicit currents with biphasic kinetics, with a fast transient component and a slower sustained component. Although it was previously reported that the sustained component is unselective for monovalent cations, the selectivity of the transient component had remained unknown. Here, we show that the transient current component arises from secondary activation of the Ca2+-activated Cl− channel (CaCC) of Xenopus oocytes. Inhibiting the activation of the CaCC leads to a simple on–off response of peptide-activated currents with no apparent desensitization. In addition, we identify a conserved ring of negative charges at the outer entrance of the HyNaC pore that is crucial for the high Ca2+ permeability, presumably by attracting divalent cations to the pore. At more positive membrane potentials, the binding of Ca2+ to the ring of negative charges increasingly blocks HyNaC currents. Thus, HyNaC is the first member of the DEG/ENaC gene family with a high Ca2+ permeability. PMID:23008433

  9. A 1500 deg2 near infrared proper motion catalogue from the UKIDSS Large Area Survey

    NASA Astrophysics Data System (ADS)

    Smith, Leigh; Lucas, P. W.; Burningham, B.; Jones, H. R. A.; Smart, R. L.; Andrei, A. H.; Catalán, S.; Pinfield, D. J.

    2014-02-01

    The United Kingdom Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) began in 2005, with the start of the UKIDSS programme as a 7 year effort to survey roughly 4000 deg2 at high Galactic latitudes in Y, J, H and K bands. The survey also included a significant quantity of two epoch J band observations, with an epoch baseline greater than 2 years to calculate proper motions. We present a near-infrared proper motion catalogue for the 1500 deg2 of the two epoch LAS data, which includes 135 625 stellar sources and a further 88 324 with ambiguous morphological classifications, all with motions detected above the 5σ level. We developed a custom proper motion pipeline which we describe here. Our catalogue agrees well with the proper motion data supplied for a 300 deg2 subset in the current Wide Field Camera Science Archive (WSA) 10th data release (DR10) catalogue, and in various optical catalogues, but it benefits from a larger matching radius and hence a larger upper proper motion detection limit. We provide absolute proper motions, using LAS galaxies for the relative to absolute correction. By using local second-order polynomial transformations, as opposed to linear transformations in the WSA, we correct better for any local distortions in the focal plane, not including the radial distortion that is removed by the UKIDSS pipeline. We present the results of proper motion searches for new brown dwarfs and white dwarfs. We discuss 41 sources in the WSA DR10 overlap with our catalogue with proper motions >300 mas yr-1, several of which are new detections. We present 15 new candidate ultracool dwarf binary systems.

  10. Model for antiorthostatic hypokinesia - Head-down tilt effects on water and salt excretion

    NASA Technical Reports Server (NTRS)

    Deavers, D. R.; Musacchia, X. J.; Meininger, G. A.

    1980-01-01

    Water and electrolyte excretion was investigated in antiorthostatic hypokinetic and orthostatic hypokinetic and control rats in metabolic cages. Significant (t test, P less than 0.05) diuresis, natriuresis, and kaliuresis occurred in the antiorthostatic hypokinetic subjects but did not occur in either the orthostatic hypokinetic or controls. Recovery from antiorthostatic hypokinesia was characterized by retention of water, sodium, and potassium. Patterns of changes in body weight and food and water consumption were virtually identical in antiorthostatic and orthostatic hypokinetic rats and thus could not account for the differences in renal handling of water and electrolytes. Also, differences in ingestion of food and water in controls could not account for differences in excretion of water and electrolytes between these and antiorthostatic hypokinetic rats. It was concluded that the antiorthostatic position was responsible for the diuresis and natriuresis and that the antiorthostatic hypokinetic rat appears to be a good model for the study of water and elecrolyte excretion during conditions such as bed rest, water immersion, and exposure to weightlessness.

  11. Analysis of Arterial Mechanics During Head-Down-Tilt Bed Rest

    NASA Technical Reports Server (NTRS)

    Elliott, Morgan B.; Martin, David S.; Westby, Christian M.; Stenger, Michael B.; Platts, Steven H.

    2014-01-01

    Carotid, brachial, and tibial arteries reacted differently to HDTBR. Previous studies have not analyzed the mechanical properties of the human brachial or anterior tibial arteries. After slight variations during bed-rest, arterial mechanical properties and IMT returned to pre-bed rest values, with the exception of tibial stiffness and PSE, which continued to be reduced post-bed rest while the DC remained elevated. The tibial artery remodeling was probably due to decreased pressure and volume. Resulting implications for longer duration spaceflight are unclear. Arterial health may be affected by microgravity, as shown by increased thoracic aorta stiffness in other ground based simulations (Aubert).

  12. Telemedicine on the move: health care heads down the information superhighway.

    PubMed

    Berek, B; Canna, M

    1994-01-01

    Telemedicine has drawn increasing attention as one of the emerging new service delivery vehicles that will run on the information superhighway. In reality, remote diagnosis and consultation through the application of telecommunications technology have been practiced for many years. But advances in technology and reform imperatives to extend access beyond traditional boundaries are pushing telemedicine into new applications. This is evidenced by the explosion in the number of pilot projects begun within the last 12 months. While demonstrating telemedicine's growing capabilities--for education and administration, as well as medical practice--these projects also raise a number of legal, clinical, and technical questions that must be answered before government and other payers will routinely reimburse for remote services. Academic and industry consortia are springing up to deal with the most compelling issues, including documenting telemedicine's safety and efficacy, developing uniform data and transmission standards, and determining the minimum resolution needed to maintain the integrity of clinical transmissions. Almost every type of medical specialty has proved amenable to performing evaluations via telemedicine links; however, specialties with less direct patient contact, like radiology and pathology, are generally identified as better candidates for telemedicine interactions. The telemedicine equipment required for these consults ranges from the simple to the ultra-sophisticated, depending on the type of system used and its clinical application. The most common system configuration involves a base station in the main facility where specialists and other consultants are housed and a number of remote referral sites. Consults are performed by interactively sharing voice, video, or image data. Increasingly, systems are being introduced that use easy-to-learn, intuitive displays and controls. Systems also require the use of any number of different communication media including land-based wire networks, high-speed fiberoptics, microwave links, or satellite transponders. Quantum leaps in telemedicine performance are being made constantly, many being swept along as a result of intensified interest in developing similar consumer and business services that are destined for the new information highway. In addition to information infrastructure projects, telemedicine has also recently benefitted from the effects of defense reinvestment, political interest in cost-reducing technologies, increased availability of funding for pilot projects, and the emergence of multifacility, multitiered, integrated delivery systems. Technical, financial, and logistical factors, which had once worked against telemedicine feasibility, are suddenly shifting to rapidly propel telemedicine technologies out of investigational settings and into mainstream clinical practice. PMID:10134202

  13. Evaluation of the Levy Method as Applied to Vibrations of a 45 deg Delta Wing

    NASA Technical Reports Server (NTRS)

    Kruszewski, Edwin T.; Waner, Paul G., Jr.

    1959-01-01

    The Levy method which deals with an idealized structure was used to obtain the natural modes and frequencies of a large-scale built-up 45 deg. delta wing. The results from this approach, both with and without the effects of transverse shear, were compared with the results obtained experimentally and also with those calculated by the Stein-Sanders method. From these comparisons it was concluded that the method as proposed by Levy gives excellent results for thin-skin delta wings, provided that corrections are made for the effect of transverse shear.

  14. U BV RI PHOTOMETRIC STANDARD STARS AROUND THE SKY AT +50 deg DECLINATION

    SciTech Connect

    Landolt, Arlo U.

    2013-11-01

    U BV RI photoelectric observations have been made of 335 stars around the sky, and centered approximately at +50 deg declination. The majority of the stars fall in the magnitude range 9 < V < 16, and in the color range –0.3 < (B – V) < +1.8. Those 243 stars best suited as new broadband photometric standard stars average 12.5 measures each from data taken on 98 different nights over a period of 17 years at the Kitt Peak National and Lowell Observatories.

  15. Microstructural characterization of nitrided beta Ti-Mo alloys at 1400 deg. C

    SciTech Connect

    Gordin, D.M.; Thibon, I.; Guillou, A.; Cornen, M.

    2010-03-15

    In this work, the two Ti{sub 92}Mo{sub 8} and Ti{sub 84}Mo{sub 16} alloy compositions were gas nitrided at 1400 deg. C. The microstructure and the chemical composition of the gas nitrided surfaces were investigated by scanning electron microscopy and by electron probe microanalysis. Two internal needle-like nitride precipitates, {alpha}-(Ti,N) and {delta}-TiN{sub 0.3}, were observed. Their crystallographic orientation relationships in the {beta} matrix were determined by electron backscattering diffraction.

  16. Pressure loss through sharp 180 deg turns in smooth rectangular channels

    NASA Astrophysics Data System (ADS)

    Metzger, D. E.; Plevich, C. W.; Fan, C. S.

    1984-07-01

    Measured pressure distributions, pressure loss coefficients, and surface streamline visualizations are presented for 180-deg turns in smooth, rectangular cross-section channels. The flow geometry models situations that exist in multipass internal cooling of gas turbine engine airfoils. The turn geometry is characterized by parameters that include the ratio of upstream and downstream channel widths, the nondimensional channel depth, the nondimensional clearance height at the tip of the turn, and the nondimensional corner fillet radius. The present results cover a range of combinations of geometry parameters and Reynolds numbers to aid in prediction of coolant flow rates in present and future cooled airfoil designs.

  17. Novel circuit configurations to design loss balanced 0 to 360-deg digital phase shifters

    NASA Astrophysics Data System (ADS)

    Yarman, Binboga S.

    1991-03-01

    Four different circuit configurations are proposed for designing wide-range low-loss balanced phase shifters capable of phase shifting between 0 and 360 deg. The phase shifting properties of three-element low/highpass symmetrical ladder networks are employed in the proposed configurations. The circuits include three switching pin diodes suitable for monolithic implementation. A numerical procedure utilized for designing minimum-loss digital phase shifters in which the diode resistance and parasitics may be included among the design parameters is outlined. It is demonstrated that the circuit configurations can yield good phase tracking capabilities up to 20 pct bandwidth with reasonable losses.

  18. The 90 deg Acoustic Spectrum of a High Speed Air Jet

    NASA Technical Reports Server (NTRS)

    Goldstein, Marvin E.

    2004-01-01

    Tam and Auriault successfully predicted the acoustic spectrum at 90deg to the axis of a high speed air jet by using an acoustic equation derived from ad hoc kinetic theory-type arguments. The present paper shows that similar predictions can be obtained by using a rigorous acoustic analogy approach together with actual measurements of the relevant acoustic source correlations. This puts the result on a firmer basis and enables its extension to new situations and to the prediction of sound at other observation angles.

  19. The cyclic stress-strain behavior of PWA 1480 at 650 deg C

    NASA Technical Reports Server (NTRS)

    Gabb, T. P.; Welsch, G. E.

    1986-01-01

    The monotonic plastic flow behavior of several single crystal nickel-base, superalloys has been shown to vary significantly with crystallographic orientation. In the present study, the cyclic plastic flow response of one such alloy, PWA 1480, was examined at 650 deg C in air. Single crystal specimens aligned near several crystallographic directions were tested in fully reversed, total-strain-controlled low cycle fatigue tests at a frequency of 0.1 Hz. The cyclic stress-strain response and general cyclic hardening behavior was analyzed as a function of crystallographic orientation and inelastic strain range.

  20. Stellar oxygen abundances. 3: The oxygen abundance of the very metal poor halo star BD -13 deg 3442

    NASA Technical Reports Server (NTRS)

    King, Jeremy R.

    1994-01-01

    A spectrum of the very metal poor ((Fe/H) approximately -3) halo star BD -13 deg 3442 is presented and used to determine this star's oxygen abundance. Our determination makes BD -13 deg 3442 the most metal poor dwarf (though a somewhat evolved one) with an O abundance determination. The O abundance (determined from the 7774 A O I triped) and (O/Fe) ratio is compared to that of two other metal-poor stars. The (O/Fe) ratio of BD -13 deg 3442 is found to be approximately 0.35 dex larger than that of the other two halo stars. Possible implications of this result are discussed.

  1. The p-wave superconductivity in the presence of Rashba interaction in 2DEG.

    PubMed

    Weng, Ke-Chuan; Hu, C D

    2016-01-01

    We investigate the effect of the Rashba interaction on two dimensional superconductivity. The presence of the Rashba interaction lifts the spin degeneracy and gives rise to the spectrum of two bands. There are intraband and interband pairs scattering which result in the coupled gap equations. We find that there are isotropic and anisotropic components in the gap function. The latter has the form of cos φk where . The former is suppressed because the intraband and the interband scatterings nearly cancel each other. Hence, -the system should exhibit the p-wave superconductivity. We perform a detailed study of electron-phonon interaction for 2DEG and find that, if only normal processes are considered, the effective coupling strength constant of this new superconductivity is about one-half of the s-wave case in the ordinary 2DEG because of the angular average of the additional in the anisotropic gap function. By taking into account of Umklapp processes, we find they are the major contribution in the electron-phonon coupling in superconductivity and enhance the transition temperature Tc. PMID:27459677

  2. MEC-2 regulates C. elegans DEG/ENaC channels needed for mechanosensation

    NASA Astrophysics Data System (ADS)

    Goodman, Miriam B.; Ernstrom, Glen G.; Chelur, Dattananda S.; O'Hagan, Robert; Yao, C. Andrea; Chalfie, Martin

    2002-02-01

    Touch sensitivity in animals relies on nerve endings in the skin that convert mechanical force into electrical signals. In the nematode Caenorhabditis elegans, gentle touch to the body wall is sensed by six mechanosensory neurons that express two amiloride-sensitive Na+ channel proteins (DEG/ENaC). These proteins, MEC-4 and MEC-10, are required for touch sensation and can mutate to cause neuronal degeneration. Here we show that these mutant or `d' forms of MEC-4 and MEC-10 produce a constitutively active, amiloride-sensitive ionic current when co-expressed in Xenopus oocytes, but not on their own. MEC-2, a stomatin-related protein needed for touch sensitivity, increased the activity of mutant channels about 40-fold and allowed currents to be detected with wild-type MEC-4 and MEC-10. Whereas neither the central, stomatin-like domain of MEC-2 nor human stomatin retained the activity of full-length MEC-2, both produced amiloride-sensitive currents with MEC-4d. Our findings indicate that MEC-2 regulates MEC-4/MEC-10 ion channels and raise the possibility that similar ion channels may be formed by stomatin-like proteins and DEG/ENaC proteins that are co-expressed in both vertebrates and invertebrates. Some of these channels may mediate mechanosensory responses.

  3. The p-wave superconductivity in the presence of Rashba interaction in 2DEG

    NASA Astrophysics Data System (ADS)

    Weng, Ke-Chuan; Hu, C. D.

    2016-07-01

    We investigate the effect of the Rashba interaction on two dimensional superconductivity. The presence of the Rashba interaction lifts the spin degeneracy and gives rise to the spectrum of two bands. There are intraband and interband pairs scattering which result in the coupled gap equations. We find that there are isotropic and anisotropic components in the gap function. The latter has the form of cos φk where . The former is suppressed because the intraband and the interband scatterings nearly cancel each other. Hence, ‑the system should exhibit the p-wave superconductivity. We perform a detailed study of electron-phonon interaction for 2DEG and find that, if only normal processes are considered, the effective coupling strength constant of this new superconductivity is about one-half of the s-wave case in the ordinary 2DEG because of the angular average of the additional in the anisotropic gap function. By taking into account of Umklapp processes, we find they are the major contribution in the electron-phonon coupling in superconductivity and enhance the transition temperature Tc.

  4. On th meridional surface profile of the Gulf Stream at 55 deg W

    NASA Technical Reports Server (NTRS)

    Hallock, Zachariah R.; Teague, William J.

    1995-01-01

    Nine-month records from nine inverted echo sounders (IESs) are analyzed to describe the mean baroclinic Gulf Stream at 55 deg W. IES acoustic travel times are converted to thermocline depth which is optimally interpolated. Kinematic and dynamic parameters (Gulf Stream meridional position, velocity, and vorticity) are calculated. Primary Gulf Stream variabiltiy is attributed to meandering and and changes in direction. A mean, stream-coordinate (relative to Gulf Stream instantaneous position and direction) meridional profile is derived and compared with results presented by other investigators. The mean velocity is estimated at 0.84 m/s directed 14 deg to the right eastward, and the thermocline (12 c) drops 657 m (north to south), corresponding to a baroclinic rise of the surface of 0.87 m. The effect of Gulf Stream curvature on temporal mean profiles is found to be unimportant and of minimal importance overall. The derived, downstream current profile is well represented by a Gaussian function and is about 190 km wide where it crosses zero. Surface baroclinic transport is estimated to be 8.5 x 10(exp 4) sq m/s, and maximum shear (flanking the maximum) is 1.2 x 10(exp -5). Results compare well with other in situ observational results from the same time period. On the other hand, analyses (by others) of concurrent satellite altimetry (Geosat) suggest a considerable narrower, more intense mean Gulf Stream.

  5. The p-wave superconductivity in the presence of Rashba interaction in 2DEG

    PubMed Central

    Weng, Ke-Chuan; Hu, C. D.

    2016-01-01

    We investigate the effect of the Rashba interaction on two dimensional superconductivity. The presence of the Rashba interaction lifts the spin degeneracy and gives rise to the spectrum of two bands. There are intraband and interband pairs scattering which result in the coupled gap equations. We find that there are isotropic and anisotropic components in the gap function. The latter has the form of cos φk where . The former is suppressed because the intraband and the interband scatterings nearly cancel each other. Hence, −the system should exhibit the p-wave superconductivity. We perform a detailed study of electron-phonon interaction for 2DEG and find that, if only normal processes are considered, the effective coupling strength constant of this new superconductivity is about one-half of the s-wave case in the ordinary 2DEG because of the angular average of the additional in the anisotropic gap function. By taking into account of Umklapp processes, we find they are the major contribution in the electron-phonon coupling in superconductivity and enhance the transition temperature Tc. PMID:27459677

  6. Detailed flow-field measurements over a 75 deg swept delta wing

    NASA Technical Reports Server (NTRS)

    Kjelgaard, Scott O.; Sellers, William L., III

    1990-01-01

    Results from an experimental investigation documenting the flowfield over a 75 deg swept delta wing at an angle-of-attack of 20.5 deg are presented. Results obtained include surface flow visualization, off-body flow visualization, and detailed flowfield surveys for various Reynolds numbers. Flowfield surveys at Reynolds numbers of 0.5, 1.0, and 1.5 million based on the root chord were conducted with both a Pitot pressure probe and a 5-hole pressure probe; and 3-component laser velocimeter surveys were conducted at a Reynolds number of 1.0 million. The Pitot pressure surveys were obtained at 5 chordwise stations, the 5-hole probe surveys were obtained at 3 chordwise stations and the laser velocimeter surveys were obtained at one station. The results confirm the classical roll up of the flow into a pair of primary vortices over the delta wing. The velocity measurements indicate that Reynolds number has little effect on the global structure of the flowfield for the Reynolds number range investigated. Measurements of the non-dimensional axial velocity in the core of the vortex indicate a jet like flow with values greater than twice freestream. Comparisons between velocity measurements from the 5-hole pressure probe and the laser velocimeter indicate that the pressure probe does a reasonable job of measuring the flowfield quantities where the velocity gradients in the flowfield are low.

  7. Year-round measurements of ozone at 66 deg S with a visible spectrometer

    NASA Technical Reports Server (NTRS)

    Roscoe, Howard K.; Oldham, Derek J.; Squires, James A. C.; Pommereau, Jean-Pierre; Goutail, Florence; Sarkissian, Alain

    1994-01-01

    In March 1990, a zenith-sky UV-visible spectrometer of the design 'Systeme Automatique d'Obervation Zenithal' (SAOZ) was installed at Faraday in Antarctica (66.3 deg S, 64.3 deg W). SAOZ records spectra between 290 and 600 nm during daylight. Its analysis program fits laboratory spectra of constituents, at various wavelengths, to the differential of the ratio of the observed spectrum and a reference spectrum. The least-squares fitting procedure minimizes the sum-of-squares of residuals. Ozone is deduced from absorption in its visible bands between 500 and 560 nm. The fortunate colocation of this SAOZ with the well-calibrated Dobson at Faraday has allowed us to examine the calibration of the zero of the SAOZ, difficult at visible wavelengths because of the small depth of absorption. Here we describe recent improvements and limitations to this calibration, and discuss SAOZ measurements of ozone during winter in this important location at the edge of the Antarctic vortex.

  8. InAs 2DEGs:What's the g-factor?

    NASA Astrophysics Data System (ADS)

    McCombe, B. D.; Pakmehr, Mehdi; Khaetskii, A.; Chiatti, Olivio; Fischer, S. F.; Buchholz, S.; Heyn, C.; Hansen, W.; Cahay, M.; Newrock, R. S.; Bandari, Nikhil

    2014-03-01

    Interest in spin-orbit effects in semiconductors has led us to study the electron g-factor in quasi-2DEG InAs samples. We have made magneto-transport and -photoresponse (PR) measurements on InAs QW structures in magnetic fields up to 10 T. THz cyclotron resonance (CR) is manifested in PR as a resonant envelope of the amplitude of quantum oscillations, which show clear spin-splitting (for lower mobility samples) down 4T, while direct R_xx measurements show no spin-splitting up to 9T. R_xx oscillations in a higher mobility sample show well-resolved spin-splittings over a range of fields as does the PR. We have simulated the data with a theoretical expression for 2DEG SdH oscillations (coupled with CR resonant carrier heating for the PR) and extracted g-factors from fits. We also used a different (commonly used) method, SdH oscillations vs. tilt angle of the field to extract g-factors from the angle at which the SdH frequency doubles. We find very large g-factors from fits to R_xx and PR (14 - 20), but g-factors 2-3 times smaller for these same samples from tilted field experiments (close to estimated band g-factors). These results are discussed in terms of exchange effects. Support: NSF DMR 1008138 (Buffalo); NSF ECCE 1028483(Cincinnati); DFG Fi932/4-1(Berlin).

  9. The DEG/ENaC cation channel protein UNC-8 drives activity-dependent synapse removal in remodeling GABAergic neurons.

    PubMed

    Miller-Fleming, Tyne W; Petersen, Sarah C; Manning, Laura; Matthewman, Cristina; Gornet, Megan; Beers, Allison; Hori, Sayaka; Mitani, Shohei; Bianchi, Laura; Richmond, Janet; Miller, David M

    2016-01-01

    Genetic programming and neural activity drive synaptic remodeling in developing neural circuits, but the molecular components that link these pathways are poorly understood. Here we show that the C. elegans Degenerin/Epithelial Sodium Channel (DEG/ENaC) protein, UNC-8, is transcriptionally controlled to function as a trigger in an activity-dependent mechanism that removes synapses in remodeling GABAergic neurons. UNC-8 cation channel activity promotes disassembly of presynaptic domains in DD type GABA neurons, but not in VD class GABA neurons where unc-8 expression is blocked by the COUP/TF transcription factor, UNC-55. We propose that the depolarizing effect of UNC-8-dependent sodium import elevates intracellular calcium in a positive feedback loop involving the voltage-gated calcium channel UNC-2 and the calcium-activated phosphatase TAX-6/calcineurin to initiate a caspase-dependent mechanism that disassembles the presynaptic apparatus. Thus, UNC-8 serves as a link between genetic and activity-dependent pathways that function together to promote the elimination of GABA synapses in remodeling neurons. PMID:27403890

  10. The DEG/ENaC cation channel protein UNC-8 drives activity-dependent synapse removal in remodeling GABAergic neurons

    PubMed Central

    Miller-Fleming, Tyne W; Petersen, Sarah C; Manning, Laura; Matthewman, Cristina; Gornet, Megan; Beers, Allison; Hori, Sayaka; Mitani, Shohei; Bianchi, Laura; Richmond, Janet; Miller, David M

    2016-01-01

    Genetic programming and neural activity drive synaptic remodeling in developing neural circuits, but the molecular components that link these pathways are poorly understood. Here we show that the C. elegans Degenerin/Epithelial Sodium Channel (DEG/ENaC) protein, UNC-8, is transcriptionally controlled to function as a trigger in an activity-dependent mechanism that removes synapses in remodeling GABAergic neurons. UNC-8 cation channel activity promotes disassembly of presynaptic domains in DD type GABA neurons, but not in VD class GABA neurons where unc-8 expression is blocked by the COUP/TF transcription factor, UNC-55. We propose that the depolarizing effect of UNC-8-dependent sodium import elevates intracellular calcium in a positive feedback loop involving the voltage-gated calcium channel UNC-2 and the calcium-activated phosphatase TAX-6/calcineurin to initiate a caspase-dependent mechanism that disassembles the presynaptic apparatus. Thus, UNC-8 serves as a link between genetic and activity-dependent pathways that function together to promote the elimination of GABA synapses in remodeling neurons. DOI: http://dx.doi.org/10.7554/eLife.14599.001 PMID:27403890

  11. Nighttime VHF scintillations at 23 deg N magnetic latitude and their association with equatorial F region irregularities

    SciTech Connect

    Dabas, R.S.; Reddy, B.M.

    1986-06-01

    Based on ETS-II geostationary satellite (130 deg E) 136-MHz radio beacon amplitudes, a study of postsunset VHF scintillations observed during the January-February 1980 solar maximum period confirms that they are essentially controlled by the generation of equatorial F region irregularities. This latitude is substantially beyond the 84.4 deg E geographic meridian equatorial anomaly daytime crest. Good agreement between the observed scintillation occurrence pattern and characteristics, and previous results reported up to 21 deg N (Somayajulu et al., 1984), is found, and the occurrence of 23 deg N scintillations is found to be conditional to their prior occurrence at lower latitudes. It is also shown that, at least during high solar activity, the equator irregularities extend to altitudes in excess of 1300 km in the Indian sector, and consequently, cause scintillations in a much wider latitudinal belt. 36 references.

  12. Transcriptomic Analysis Identifies Differentially Expressed Genes (DEGs) Associated with Bolting and Flowering in Radish (Raphanus sativus L.)

    PubMed Central

    Nie, Shanshan; Li, Chao; Wang, Yan; Xu, Liang; Muleke, Everlyne M.; Tang, Mingjia; Sun, Xiaochuan; Liu, Liwang

    2016-01-01

    The transition of vegetative growth to bolting and flowering is an important process in the life cycle of plants, which is determined by numerous genes forming an intricate network of bolting and flowering. However, no comprehensive identification and profiling of bolting and flowering-related genes have been carried out in radish. In this study, RNA-Seq technology was applied to analyze the differential gene expressions during the transition from vegetative stage to reproductive stage in radish. A total of 5922 differentially expressed genes (DEGs) including 779 up-regulated and 5143 down-regulated genes were isolated. Functional enrichment analysis suggested that some DEGs were involved in hormone signaling pathways and the transcriptional regulation of bolting and flowering. KEGG-based analysis identified 37 DEGs being involved in phytohormone signaling pathways. Moreover, 95 DEGs related to bolting and flowering were identified and integrated into various flowering pathways. Several critical genes including FT, CO, SOC1, FLC, and LFY were characterized and profiled by RT-qPCR analysis. Correlation analysis indicated that 24 miRNA-DEG pairs were involved in radish bolting and flowering. Finally, a miRNA-DEG-based schematic model of bolting and flowering regulatory network was proposed in radish. These outcomes provided significant insights into genetic control of radish bolting and flowering, and would facilitate unraveling molecular regulatory mechanism underlying bolting and flowering in root vegetable crops. PMID:27252709

  13. DEG/ENaC but not TRP channels are the major mechanoelectrical transduction channels in a C. elegans nociceptor

    PubMed Central

    Geffeney, Shana L.; Cueva, Juan G.; Glauser, Dominique A.; Doll, Joseph C.; Lee, Tim Hau-Chen; Montoya, Misty; Karania, Snetu; Garakani, Arman M.; Pruitt, Beth L.; Goodman, Miriam B.

    2011-01-01

    Summary Many nociceptors detect mechanical cues, but the ion channels responsible for mechanotransduction in these sensory neurons remain obscure. Using in vivo recordings and genetic dissection, we identified the DEG/ENaC protein, DEG-1, as the major mechanotransduction channel in ASH, a polymodal nociceptor in Caenorhabditis elegans. But, DEG-1 is not the only mechanotransduction channel in ASH: loss of deg-1 revealed a minor current whose properties differ from those expected of DEG/ENaC channels. This current was independent of two TRPV channels expressed in ASH. Although loss of these TRPV channels inhibits behavioral responses to noxious stimuli, we found that both mechanoreceptor currents and potentials were essentially wild-type in TRPV mutants. We propose that ASH nociceptors rely on two genetically-distinct mechanotransduction channels and that TRPV channels contribute to encoding and transmitting information. Because mammalian and insect nociceptors also co-express DEG/ENaCs and TRPVs, the cellular functions elaborated here for these ion channels may be conserved. PMID:21903078

  14. A new principle of oligomerization of plant DEG7 protease based on interactions of degenerated protease domains

    PubMed Central

    Schuhmann, Holger; Mogg, Ulrike; Adamska, Iwona

    2011-01-01

    Deg/HtrA proteases are a large group of ATP-independent serine endoproteases found in almost every organism. Their usual domain arrangement comprises a trypsin-type protease domain and one or more PDZ domains. All Deg/HtrA proteases form homo-oligomers with trimers as the basic unit, where the active protease domain mediates the interaction between individual monomers. Among the members of the Deg/HtrA protease family, the plant protease DEG7 is unique since it contains two protease domains (one active and one degenerated) and four PDZ domains. In the present study, we investigated the oligomerization behaviour of this unusual protease using yeast two-hybrid analysis in vivo and with recombinant protein in vitro. We show that DEG7 forms trimeric complexes, but in contrast with other known Deg/HtrA proteases, it shows a new principle of oligomerization, where trimerization is based on the interactions between degenerated protease domains. We propose that, during evolution, a duplicated active protease domain degenerated and specialized in protein–protein interaction and complex formation. PMID:21247409

  15. Transcriptomic Analysis Identifies Differentially Expressed Genes (DEGs) Associated with Bolting and Flowering in Radish (Raphanus sativus L.).

    PubMed

    Nie, Shanshan; Li, Chao; Wang, Yan; Xu, Liang; Muleke, Everlyne M; Tang, Mingjia; Sun, Xiaochuan; Liu, Liwang

    2016-01-01

    The transition of vegetative growth to bolting and flowering is an important process in the life cycle of plants, which is determined by numerous genes forming an intricate network of bolting and flowering. However, no comprehensive identification and profiling of bolting and flowering-related genes have been carried out in radish. In this study, RNA-Seq technology was applied to analyze the differential gene expressions during the transition from vegetative stage to reproductive stage in radish. A total of 5922 differentially expressed genes (DEGs) including 779 up-regulated and 5143 down-regulated genes were isolated. Functional enrichment analysis suggested that some DEGs were involved in hormone signaling pathways and the transcriptional regulation of bolting and flowering. KEGG-based analysis identified 37 DEGs being involved in phytohormone signaling pathways. Moreover, 95 DEGs related to bolting and flowering were identified and integrated into various flowering pathways. Several critical genes including FT, CO, SOC1, FLC, and LFY were characterized and profiled by RT-qPCR analysis. Correlation analysis indicated that 24 miRNA-DEG pairs were involved in radish bolting and flowering. Finally, a miRNA-DEG-based schematic model of bolting and flowering regulatory network was proposed in radish. These outcomes provided significant insights into genetic control of radish bolting and flowering, and would facilitate unraveling molecular regulatory mechanism underlying bolting and flowering in root vegetable crops. PMID:27252709

  16. Spectra and angular distributions of atmospheric gamma rays from 0.3 to 10 MeV at lambda = 40 deg

    NASA Technical Reports Server (NTRS)

    Ling, J. C.; Gruber, D. E.

    1977-01-01

    Measurements of the spectral and angular distributions of atmospheric gamma sq cm rays in the energy range 0.3-10 MeV over Palestine, Texas, at residual depths of 2.5 and 70 g/sq cm are reported. In confirmation of the general features of a model prediction, the measurements show at 2.5 g/sq cm upward moving fluxes greater than the downward moving fluxes, the effect increasing with energy, and approximate isotropy at 70 g/sq cm. Numerous characteristic gamma-ray lines were observed, most prominently at 0.511, 1.6, 2.3, 4.4, and 6.1 MeV. Their intensities were also compared with model predictions. Observations were made with an actively shielded scintillator counter with two detectors, one of aperture 50 deg FWHM and the other of 120 deg FWHM. Above 1 MeV, contributions to the counting rate from photons penetrating the shield annulus and from neutron interactions were large; they were studied by means of a Monte Carlo code and are extensively discussed.

  17. BD-22deg3467, a DAO-type Star Exciting the Nebula Abell 35

    NASA Technical Reports Server (NTRS)

    Ziegler, M.; Rauch, T.; Werner, K.; Koppen, J.; Kruk, J. W.

    2013-01-01

    Spectral analyses of hot, compact stars with non-local thermodynamical equilibrium (NLTE) model-atmosphere techniques allow the precise determination of photospheric parameters such as the effective temperature (T(sub eff)), the surface gravity (log g), and the chemical composition. The derived photospheric metal abundances are crucial constraints for stellar evolutionary theory. Aims. Previous spectral analyses of the exciting star of the nebula A35, BD-22deg3467, were based on He+C+N+O+Si+Fe models only. For our analysis, we use state-of-the-art fully metal-line blanketed NLTE model atmospheres that consider opacities of 23 elements from hydrogen to nickel. We aim to identify all observed lines in the ultraviolet (UV) spectrum of BD-22deg3467 and to determine the abundances of the respective species precisely. Methods. For the analysis of high-resolution and high signal-to-noise ratio (S/N) far-ultraviolet (FUSE) and UV (HST/STIS) observations, we combined stellar-atmosphere models and interstellar line-absorption models to fully reproduce the entire observed UV spectrum. Results. The best agreement with the UV observation of BD-22deg3467 is achieved at T(sub eff) = 80 +/- 10 kK and log g = 7.2 +/- 0.3. While T(sub eff) of previous analyses is verified, log g is significantly lower. We re-analyzed lines of silicon and iron (1/100 and about solar abundances, respectively) and for the first time in this star identified argon, chromium, manganese, cobalt, and nickel and determined abundances of 12, 70, 35, 150, and 5 times solar, respectively. Our results partially agree with predictions of diffusion models for DA-type white dwarfs. A combination of photospheric and interstellar line-absorption models reproduces more than 90% of the observed absorption features. The stellar mass is M approx. 0.48 Solar Mass. Conclusions. BD.22.3467 may not have been massive enough to ascend the asymptotic giant branch and may have evolved directly from the extended horizontal branch

  18. A 189 MHz, 2400 deg{sup 2} POLARIZATION SURVEY WITH THE MURCHISON WIDEFIELD ARRAY 32-ELEMENT PROTOTYPE

    SciTech Connect

    Bernardi, G.; Greenhill, L. J.; De Oliveira-Costa, A.; Mitchell, D. A.; Ord, S. M.; Arcus, W.; Arora, B. S.; Hazelton, B. J.; Morales, M. F.; Gaensler, B. M.; Subrahmanyan, R.; Wayth, R. B.; Lenc, E.; Briggs, F. H.; Shankar, N. Udaya; Williams, C. L.; Barnes, D. G.; Bowman, J. D.; Bunton, J. D.; Cappallo, R. J.; and others

    2013-07-10

    We present a Stokes I, Q and U survey at 189 MHz with the Murchison Widefield Array 32 element prototype covering 2400 deg{sup 2}. The survey has a 15.6 arcmin angular resolution and achieves a noise level of 15 mJy beam{sup -1}. We demonstrate a novel interferometric data analysis that involves calibration of drift scan data, integration through the co-addition of warped snapshot images, and deconvolution of the point-spread function through forward modeling. We present a point source catalog down to a flux limit of 4 Jy. We detect polarization from only one of the sources, PMN J0351-2744, at a level of 1.8% {+-} 0.4%, whereas the remaining sources have a polarization fraction below 2%. Compared to a reported average value of 7% at 1.4 GHz, the polarization fraction of compact sources significantly decreases at low frequencies. We find a wealth of diffuse polarized emission across a large area of the survey with a maximum peak of {approx}13 K, primarily with positive rotation measure values smaller than +10 rad m{sup -2}. The small values observed indicate that the emission is likely to have a local origin (closer than a few hundred parsecs). There is a large sky area at {alpha} {>=} 2{sup h}30{sup m} where the diffuse polarized emission rms is fainter than 1 K. Within this area of low Galactic polarization we characterize the foreground properties in a cold sky patch at ({alpha}, {delta}) = (4{sup h}, -27. Degree-Sign 6) in terms of three-dimensional power spectra.

  19. Evaluation of load-life relation with ball bearings at 500 deg F

    NASA Technical Reports Server (NTRS)

    Parker, R. J.; Zaretsky, E. V.; Bamberger, E. N.

    1973-01-01

    A survey of the literature suggests that a stress-life exponent of approximately 12 is typical of vacuum-processed steels for ball bearings rather than the exponent of 9 which has been generally accepted by the bearing industry and bearing users. Tests run with vacuum-degassed AISI 52100 balls in the five-ball fatigue tester at four maximum Hertz stress levels in the range from 650000 to 875000 psi showed good agreement with the literature. However, tests run with consumable-electrode vacuum melted AISI M-50 steel angular-contact ball bearings at 500 deg F at three thrust loads did not show significant deviation from the accepted ninth power stress-life relation.

  20. An occultation of the star AGK 3 + 4 deg 3142 by the tail of Halley's comet

    NASA Astrophysics Data System (ADS)

    Wang, Luyou; Qian, Bochen; Zhu, Guoliang; Fan, Qingyuan; Li, Xiaoyong

    An event that the star AGK 3 + 4 deg 3142 was occulted by Halley's tail was observed with a phi 400 mm refractor located at So-Se Hill and the photometric system on November 13,1985. The time of occultation was from 14h 44m to 15h 01m 04s U. T., the endurance being about 17m 04s. Light curves when the occultation phenomenon happened and not, respectively, are given. Both the curves are the weighted average results for each five observational points. The average and error bar counts when the star had not been occulted are shown. It seems from the results that the tail of Halley's comet may have been split sometime.

  1. SAGE II observations of polar stratospheric clouds near 50 deg N January 31 - February 2, 1989

    NASA Technical Reports Server (NTRS)

    Pitts, M. C.; Poole, L. R.; Mccormick, M. P.

    1990-01-01

    Polar stratospheric clouds (PSCs) form at very cold temperatures which typically occur only at high latitudes during local winter. However, meteorological circumstances in the Arctic during late January 1989 led to PSC formation unusually far to the south, at latitudes (near 50 deg N) being sampled during the period by the orbiting SAGE II instrument. These unusual PSC sightings and the evolution of meteorological conditions which produced the episode are described. Profiles of SAGE II extinction measurements at 0.525 and 1.02 microns show clear signatures of PSCs and indicate that the cloud particles were considerably larger than the background aerosol. It is most important to note that the clouds were sighted at a latitude where there was extensive sunlight, thus increasing the likelihood of ozone loss both locally and downstream due to enhancements in reactive chlorine expected from heterogeneous chemical processing within the PSCs.

  2. Design procedure for flexibility factors of 90-Deg curved pipe having various tangent lengths

    SciTech Connect

    Nordham, D.J. . Carderock Division); Kaldor, L.M.

    1993-08-01

    A simple design procedure, based on 175 finite element analyses, was derived to predict the flexibility factor due to an in-plane or out-of-plane moment for a 90-deg curved pipe with end constraints composed of tangents of any length terminated by rigid flanges and no internal pressure loads. The results of this design procedure were then compared to flexibility factors obtained from additional finite element analyses and experimental work. Flexibility factors calculated using the design equations in the Power Piping Code (ANSI/ASME B31.1-1986) were also compared to all finite element and experimental work. It was found that this design procedure more accurately predicts the flexibility factors than the Power Piping Code.

  3. Design procedure for stress intensification factors of 90-Deg curved pipe having various tangent lengths

    SciTech Connect

    Nordham, D.J. . Carderock Division); Kaldor, L.M.

    1993-08-01

    A simple design procedure, based on 114 finite element analyses, was derived to predict the stress intensification factor for 90-deg curved pipe with end constraints composed of tangents of any length terminated by rigid flanges and no internal pressure loads. The results of this design procedure were then compared to stress intensification factors obtained from additional finite element analyses and experimental work. Stress intensification factors calculated using the design equations in the Power Piping Code (ANSI/ASME B31.1-1986) were also compared to all the finite element and experimental work. It was found that this design procedure more accurately predicts the stress intensification factors than the Power Piping Code.

  4. Aerodynamic investigation of the flow field in a 180 deg turn channel with sharp bend

    NASA Astrophysics Data System (ADS)

    Rau, Guido; Arts, Tony

    1994-07-01

    The internal cooling of gas turbine blades is generally ensured by secondary air flowing through narrow passages existing inside the airfoils. These internal channels are usually connected by 180 deg turns with sharp bends. The aerodynamic and associated convective heat transfer characteristics observed in this type of geometry are significantly influenced by strong secondary flows and flow separations. The purpose of the present experimental effort is to give a detailed description of some aerodynamic aspects of this particular flow pattern. Detailed measurements of the three-dimensional velocity field were performed by means of a two-component Laser Doppler Velocimeter. The third velocity component was obtained by repeating the measurements at two different orientations of the emitting optics with respect to the test section.

  5. Numerical Analysis of Incipient Separation on 53 Deg Swept Diamond Wing

    NASA Technical Reports Server (NTRS)

    Frink, Neal T.

    2015-01-01

    A systematic analysis of incipient separation and subsequent vortex formation from moderately swept blunt leading edges is presented for a 53 deg swept diamond wing. This work contributes to a collective body of knowledge generated within the NATO/STO AVT-183 Task Group titled 'Reliable Prediction of Separated Flow Onset and Progression for Air and Sea Vehicles'. The objective is to extract insights from the experimentally measured and numerically computed flow fields that might enable turbulence experts to further improve their models for predicting swept blunt leading-edge flow separation. Details of vortex formation are inferred from numerical solutions after establishing a good correlation of the global flow field and surface pressure distributions between wind tunnel measurements and computed flow solutions. From this, significant and sometimes surprising insights into the nature of incipient separation and part-span vortex formation are derived from the wealth of information available in the computational solutions.

  6. Streakline flow visualization of discrete hole film cooling with holes inclined 30 deg to surface

    NASA Technical Reports Server (NTRS)

    Colladay, R. S.; Russell, L. M.; Lane, J. M.

    1976-01-01

    Film injection from three rows of discrete holes angled 30 deg to the surface in line with mainstream flow and spaced 5 diameters apart in a staggered array was visualized by using helium bubbles as tracer particles. Both the main stream and the film injectant were ambient air. Detailed streaklines showing the turbulent motion of the film mixing with the main stream were obtained by photographing small, neutrally buoyant helium-filled soap bubbles which followed the flow field. The ratio of boundary layer thickness to hole diameter and the Reynolds number were typical of gas turbine film cooling applications. The results showed the behavior of the film and its interaction with the main stream for a range of blowing rates and two initial boundary layer thicknesses.

  7. Computer simulation of a 360 deg field-of-view 'top-hat' electrostatic analyzer

    NASA Astrophysics Data System (ADS)

    Sablik, M. J.; Golimowski, D.; Sharber, J. R.; Winningham, J. D.

    1988-01-01

    The characteristics of the 'top-hat' electrostatic analyzer which has a 360-deg field of view in the acceptance plane were studied via computer simulation. A finite-difference method employing a polar mesh was used for the computation of the electrostatic field inside the analyzer, and a three-dimensional ray-tracing technique was used for the computation of the particle trajectories. It is shown that the exit angular response is extremely sharp and can be made sharper by truncating the turn angle of the analyzer; there is no energy-angle skewing for particle beams parallel to the acceptance plane; transmission can be maximized for normal incidence with respect to the analyzer axis; the exit velocity distribution is peaked sharply in one direction and can be made sharper by imposing an entrance mask; and the analyzer has a large geometric factor.

  8. Modeling and computation of flow in a passage with 360 deg turning and multiple airfoils

    NASA Astrophysics Data System (ADS)

    Shyy, W.; Vu, T. C.

    1991-06-01

    Numerical modeling of the three-dimensional flows in a spiral casing of a hydraulic turbine, containing a passage of 360-deg turning and multiple elements of airfoils (the so-called distributor), is made. The physical model is based on a novel two-level approach, comprising of (1) a global model that adequately accounts for the geometry of the spiral casing but smears out the details of the distributor and represents the multiple airfoils by a porous medium treatment; and (2) a local model that performs detailed analysis of flow in the distributor region. The global analysis supplies the inlet flow condition for the individual cascade of distributor airfoils, while the distributor analysis yields the information needed for modeling the characteristics of the porous medium. Comparisons of pressure and velocity profiles between measurement and prediction have been made to assess the validity of the present approach. Flow characteristics in the spiral casing are also discussed.

  9. J-PAS : Low-resolution (R ~ 50) spectroscopy covering 8000 deg2

    NASA Astrophysics Data System (ADS)

    López-Sanjuan, C.; Cenarro, A. J.; Díaz-García, L. A.; Muniesa, D. J.; San Roman, I.; Varela, J.; Viironen, K.

    2015-02-01

    We present the ambitious project J-PAS, that will cover 8000 deg2 of the northern sky with 54 narrow-band (~145Å) contiguous filters, all of them in the optical range (3700Å-9200Å). J-PAS will provide a low resolution spectra (R ~ 50) in every pixel of the northern sky by 2020, leading to excellent photometric redshifts (0.3% uncertainty) of 100 million sources. J-PAS will permit the study of the 2D properties of nearby galaxies with unprecedented statistics. Some viable studies are the distribution of the star formation rate traced by Hα, the stellar populations gradients in elliptical galaxies up to a few effective radii, or the impact of environment in galaxy properties. In summary, J-PAS will bring a superb data set for 3D analysis in the local Universe.

  10. An experimental study of pressures on 60 deg Delta wings with leading edge vortex flaps

    NASA Technical Reports Server (NTRS)

    Marchman, J. F., III; Terry, J. E.; Donatelli, D. A.

    1983-01-01

    An experimental study was conducted in the Virginia Tech Stability Wind Tunnel to determine surface pressures over a 60 deg sweep delta wing with three vortex flap designs. Extensive pressure data was collected to provide a base data set for comparison with computational design codes and to allow a better understanding of the flow over vortex flaps. The results indicated that vortex flaps can be designed which will contain the leading edge vortex with no spillage onto the wing upper surface. However, the tests also showed that flaps designed without accounting for flap thickness will not be optimum and the result can be oversized flaps, early flap vortex reattachment and a second separation and vortex at the wing/flap hinge line.

  11. Pressure investigation of NASA leading edge vortex flaps on a 60 deg Delta wing

    NASA Technical Reports Server (NTRS)

    Marchman, J. F., III; Donatelli, D. A.; Terry, J. E.

    1983-01-01

    Pressure distributions on a 60 deg Delta Wing with NASA designed leading edge vortex flaps (LEVF) were found in order to provide more pressure data for LEVF and to help verify NASA computer codes used in designing these flaps. These flaps were intended to be optimized designs based on these computer codes. However, the pressure distributions show that the flaps wre not optimum for the size and deflection specified. A second drag-producing vortex forming over the wing indicated that the flap was too large for the specified deflection. Also, it became apparent that flap thickness has a possible effect on the reattachment location of the vortex. Research is continuing to determine proper flap size and deflection relationships that provide well-behaved flowfields and acceptable hinge-moment characteristics.

  12. Concentric ring and Jerusalem cross arrays as frequency selective surfaces for a 45 deg incidence diplexer

    NASA Astrophysics Data System (ADS)

    Cahill, R.; Parker, E. A.

    1982-04-01

    It is pointed out that, with respect to ease of manufacture, plane reflectors have a distinct advantage over curved reflectors. Since theoretical modelling is also usually easier for plane frequency selective surfaces, it is of interest to study dual-band feeds incorporating them. In the present investigation a comparison is conducted of the linear crosspolar performances of two single layer plane arrays of elements, including standard Jerusalem crosses (without the inductive grid) and concentric rings. The results for the two arrays are presented in graphs for the frequency ranges where the copolar loss was 0.5 dB or less. A dependence by up to 5 dB of crosspolar levels on plane of incidence for gridded Jerusalem crosses was noted for reflection only by Arnaud and Pelow (1975) for incident at 20 deg. The results of the present investigation show that this effect can also be significant for Jerusalem crosses in transmission.

  13. A low speed wind tunnel investigation of Reynolds number effects on a 60-deg swept wing configuration with leading and trailing edge flaps

    NASA Technical Reports Server (NTRS)

    Rao, Dhanvada M.; Hoffler, Keith D.

    1988-01-01

    A low-speed wind tunnel test was performed to investigate Reynolds number effects on the aerodynamic characteristics of a supersonic cruise wing concept model with a 60-deg swept wing incorporating leading-edge and trailing-edge flap deflections. The Reynolds number ranged from 0.3 to 1.6 x 10 to the 6th, and corresponding Mach numbers from .05 to 0.3. The objective was to define a threshold Reynolds number above which the flap aerodynamics basically remained unchanged, and also to generate a data base useful for validating theoretical predictions for the Reynolds number effects on flap performance. This report documents the test procedures used and the basic data acquired in the investigation.

  14. Clementine High Resolution Camera Mosaicking Project. Volume 21; CL 6021; 80 deg S to 90 deg S Latitude, North Periapsis; 1

    NASA Technical Reports Server (NTRS)

    Malin, Michael; Revine, Michael; Boyce, Joseph M. (Technical Monitor)

    1998-01-01

    second half. Images in each group have generally uniform intrinsic resolution, illumination, exposure and gain. Rather than mingle data from the two periapsis epochs, separate mosaics are provided for each, a total of 4 polar mosaics. The mosaics are divided into 100 square tiles of 2250 pixels (approximately 2.2 deg near the pole) on a side. Not all squares of this grid contain HiRes mosaic data, some inevitably since a square is not a perfect representation of a (latitude) circle, others due to the lack of HiRes data. This CD also contains ancillary data files that support the HiRes mosaic. These files include browse images with UV/Vis context stored in a Joint Photographic Experts Group (JPEG) format, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the "FILES, DIRECTORIES AND DISK CONTENTS" section of this document. The image files are organized according to NASA's Planetary Data System (PDS) standards. An image file (tile) is organized as a PDS labeled file containing an "image object".

  15. Clementine High Resolution Camera Mosaicking Project. Volume 19; CL 6019; 80 deg N to 90 deg N Latitude, North Periapsis; 1

    NASA Technical Reports Server (NTRS)

    Malin, Michael; Revine, Michael; Boyce, Joseph M. (Technical Monitor)

    1998-01-01

    second half. Images in each group have generally uniform intrinsic resolution, illumination, exposure and gain. Rather than mingle data from the two periapsis epochs, separate mosaics are provided for each, a total of 4 polar mosaics. The mosaics are divided into 100 square tiles of 2250 pixels (approximately 2.2 deg near the pole) on a side. Not all squares of this grid contain HiRes mosaic data, some inevitably since a square is not a perfect representation of a (latitude) circle, others due to the lack of HiRes data. This CD also contains ancillary data files that support the HiRes mosaic. These files include browse images with UV/Vis context stored in a Joint Photographic Experts Group (JPEG) format, index files ('imgindx.tab' and 'srcindx.tab') that tabulate the contents of the CD, and documentation files. For more information on the contents and organization of the CD volume set refer to the "FILES, DIRECTORIES AND DISK CONTENTS" section of this document. The image files are organized according to NASA's Planetary Data System (PDS) standards. An image file (tile) is organized as a PDS labeled file containing an "image object".

  16. Space shuttle: Aerodynamic stability, control effectiveness and drag characteristics of a shuttle orbiter configuration at Mach numbers from 0.6 to 4.96

    NASA Technical Reports Server (NTRS)

    Ramsey, P. E.

    1972-01-01

    Experimental aerodynamic investigations were conducted in the NASA/MSFC 14-inch Trisonic Wind Tunnel from Sept. 27 to Oct. 7, 1972 on a 0.004 scale model of the NR ATP baseline shuttle orbiter configuration. Six component aerodynamic force and moment data were recorded at 0 deg sideslip angle over an angle of attack range from 0 to 20 deg for Mach numbers of 0.6 to 4.96, 20 to 40 deg for Mach numbers of 0.6, 0.9, 2.99, and 4.96, and 40 to 60 deg for Mach numbers of 2.99 and 4.96. Data were obtained over a sideslip range of -10 to 10 deg at 0, 10, and 20 deg angles of attack over the Mach range and 30 and 50 deg at Mach numbers of 2.99 and 4.96. The purpose of the test was to define the buildup, performance, stability, and control characteristics of the orbiter configuration. The model parameters, were: body alone; body-wing; body-wing-tail; elevon deflections of 0, 10, -20, and -40 deg both full and split); aileron deflections of plus or minus 10 deg (full and split); rudder flares of 10 and 40 deg, and a rudder deflection of 15 deg about the 10 and 40 deg flare positions.

  17. MEC-10 and MEC-19 Reduce the Neurotoxicity of the MEC-4(d) DEG/ENaC Channel in Caenorhabditis elegans

    PubMed Central

    Chen, Yushu; Bharill, Shashank; O’Hagan, Robert; Isacoff, Ehud Y.; Chalfie, Martin

    2016-01-01

    The Caenorhabditis elegans DEG/ENaC proteins MEC-4 and MEC-10 transduce gentle touch in the six touch receptor neurons . Gain-of-function mutations of mec-4 and mec-4(d) result in a hyperactive channel and neurodegeneration in vivo. Loss of MEC-6, a putative DEG/ENaC-specific chaperone, and of the similar protein POML-1 suppresses the neurodegeneration caused by a mec-4(d) mutation. We find that mutation of two genes, mec-10 and a new gene mec-19 (previously named C49G9.1), prevents this action of POML-1, allowing the touch receptor neurons to die in poml-1mec-4(d) animals. The proteins encoded by these genes normally inhibit mec-4(d) neurotoxicity through different mechanisms. MEC-10, a subunit of the mechanosensory transduction channel with MEC-4, inhibits MEC-4(d) activity without affecting MEC-4 expression. In contrast, MEC-19, a membrane protein specific to nematodes, inhibits MEC-4(d) activity and reduces MEC-4 surface expression. PMID:27172609

  18. Infrared magneto-transmission studies of the 2DEGs in (CdMn)Te and CdTe Quantum wells

    NASA Astrophysics Data System (ADS)

    Tanveer, Imtiaz; Wiater, Maciej; Karczewski, Grzegorz; Wojtowicz, Tomasz; McCombe, B. D.

    We are probing quantum hall ferromagnetism (QHF) in the 2DEG of Modulation-doped quantum wells (QWs) in the (CdMn)Te/(CdMg)Te (with 1.5% Mn) heterostructure system by THz cyclotron resonance. Samples with CdTe QWs are also studied. Both structures have the same QW width (30 nm), very similar electron densities in the wells ~3.0 x 1011 cm-2 and mobilities of 450,000 (CdTe) and 66,000 cm2/Vs ((CdMn)Te) at 1.6 K. The electron effective masses (m*/m0) from cyclotron resonance measurements at 5K are 0.110 +/- 0.001 for CdTe and 0.114 +/- 0.003 for (CdMn)Te . Linear fits to the resonance positions in frequency vs. field give small non-zero intercepts which may result from small non-parabolicity or bound magneto-plasmon effects. The FWHM linewidths from Lorentzian fits of the transmission minima are ~2 cm-1(CdTe) and ~8 cm-1((CdMn)Te). Our present focus is on detailed studies of the CR positions and linewidths in the magnetic field region around the cusp-like behavior in the Rxx oscillations, which indicates the presence of the QHF state. The field position of this state is tuned via electron density in the QWs varied incrementally by a photon-dose method with an in-situ green LED. Work at UB was supported in part by the Office of the Provost, and work in Poland was supported in part by the National Science Centre through Grant DEC-2012/06/A/ST3/00247.

  19. Cosmological constraints from the 100-deg2 weak-lensing survey

    NASA Astrophysics Data System (ADS)

    Benjamin, Jonathan; Heymans, Catherine; Semboloni, Elisabetta; van Waerbeke, Ludovic; Hoekstra, Henk; Erben, Thomas; Gladders, Michael D.; Hetterscheidt, Marco; Mellier, Yannick; Yee, H. K. C.

    2007-10-01

    We present a cosmic shear analysis of the 100-deg2 weak-lensing survey, combining data from the CFHTLS-Wide, RCS, VIRMOS-DESCART and GaBoDS surveys. Spanning ~100 deg2, with a median source redshift z ~ 0.78, this combined survey allows us to place tight joint constraints on the matter density parameter Ωm, and the amplitude of the matter power spectrum σ8, finding σ8(Ωm/0.24)0.59 = 0.84 +/- 0.05. Tables of the measured shear correlation function and the calculated covariance matrix for each survey are included as supplementary material to the online version of this article. The accuracy of our results is a marked improvement on previous work owing to three important differences in our analysis; we correctly account for sample variance errors by including a non-Gaussian contribution estimated from numerical simulations; we correct the measured shear for a calibration bias as estimated from simulated data; we model the redshift distribution, n(z), of each survey from the largest deep photometric redshift catalogue currently available from the CFHTLS-Deep. This catalogue is randomly sampled to reproduce the magnitude distribution of each survey with the resulting survey-dependent n(z) parametrized using two different models. While our results are consistent for the n(z) models tested, we find that our cosmological parameter constraints depend weakly (at the 5 per cent level) on the inclusion or exclusion of galaxies with low-confidence photometric redshift estimates (z > 1.5). These high-redshift galaxies are relatively few in number but contribute a significant weak-lensing signal. It will therefore be important for future weak-lensing surveys to obtain near-infrared data to reliably determine the number of high-redshift galaxies in cosmic shear analyses. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada (NRCC), the Institut des Sciences de l'Univers (INSU) of the Centre

  20. Segmentation and a nontransform ridge offset of the Reykjanes Ridge near 58 deg N

    NASA Astrophysics Data System (ADS)

    Searle, R. C.; Field, P. R.; Owens, R. B.

    1994-12-01

    Multibeam bathymetry, deep-towed side scan sonar, gravity, and magnetic data over a 50 km square area all suggest the presence of a second-order, nontransform offset on the obliquely spreading Reykjanes Ridge (North Atlantic ocean) near 58 deg N latitude. It is the first such offset to be recognized on the Reykjanes Ridge. This region is characterized by a shallow median valley containing en echelon axial volcanic ridges (AVRs) similar to those found on more northerly parts of the Reykjanes Ridge. The side scan sonar shows that all the AVRs are constructional in nature. The one immediately south of the offset basin backscatters strongly, is unmarked by faulting, and so appears extremely young. Other AVRs appear older, having lower backscatter and, off axis, being cut by faults and fissures. At 57 deg 55 min N the progression of AVRs is interrupted by a 600-m-deep, 20 km x 10 km basin. Residual mantle Bouguer anomalies, corrected for two-dimensional lithospheric cooling, display a high of at least 8 mGal over the basin. Two small, off axis basins occur roughly along the flow line from this basin and are also characterized by gravity highs. The basins are interpreted as regions of crustal thinning and are believed to represent the discontinuous trace of the ridge offset, which has thus been in existence for at least 2 m.y. and has been slowly propagating south. Inversion of the magnetic field shows a very low magnetization (approximately 3-4 A/m) associated with the offset basin, which is interpreted as indicating a reduced magnetic layer thickness due to poor magma supply to the offset area. The Brunhes-Matuyama reversal boundary and Anomaly 2 traces are offset about 3 km dextrally across the proposed offset trace. The AVR immediately north of the offset displays high amplitudes of magnetization which steadily increase southward toward its tip adjacent to the offset, suggesting the presence of increasingly highly fractionated basalts toward the AVR tip. Polarity

  1. Interaction between excitons and 2DEG Landau levels in modulation doped GaAs/AlGaAs heterojunctions

    NASA Astrophysics Data System (ADS)

    Preezant, Yulia; Gabbay, A.; Eitan, A. A.; Ashkinadze, B. M.; Cohen, E.; Pfeiffer, L. N.

    2007-04-01

    The reflection and photoluminescence spectra of n-type, modulation-doped GaAs/AlxGa1-xAs wide quantum wells (QW) and heterojunctions (HJ) were studied at T = 2K and under a perpendicularly applied magnetic field. The spectra show two groups of very sharp lines that originate in two types of excitations: excitons, whose center of mass motion is quantized, and interband Landau transitions of the 2DEG, that is confined to the QW edges. Abrupt energy and intensity variations of both types of lines are observed at filling factors ν = 1,2 of the 2DEG. These variations are interpreted in terms of an interaction between excitations that are spatially confined in separate parts of the wide QW (or HJ). It leads to energy level splittings and increased exciton dissociation by the magnetized 2DEG layer.

  2. Effects of hydrogen impurities on the lattice thermal diffusivity of quartz and quartzites up to 1000\\deg C

    NASA Astrophysics Data System (ADS)

    Branlund, J. M.; Hofmeister, A. M.

    2004-12-01

    The phonon contribution to thermal diffusivity (Dlat) in quartz single-crystals was measured using a laser flash apparatus between room temperature and 1000\\deg C. Our measurements revealed differences in Dlat between samples which most likely result from hydroxyl impurities. Variations in Dlat between wet and dry samples persist above the α to β transition. For all samples, Dlat follows a 1/T trend. Unlike previous measurements, thermal diffusivity of β -quartz remains constant or decreases slightly with increasing temperature, showing that the technique removes radiative transfer effects. The difference between samples is of greatest interest. The two orientations of a quartz single-crystal containing 171 H/106 Si as OH defects have Dlat vales at room temperature that are 22% and 41% lower than equivalent orientations for a dry sample. The effect of defects on Dlat is amplified when the OH-dipole is parallel to the electromagnetic vector of the diffusing heat. Oriented milky quartz samples with 1260 to 2100 H/6 Si have Dlat 12-15% lower than dry quartz values, suggesting that fluid inclusions slow thermal diffusion to a smaller degree. Room temperature Dlat of 5 different quartzite samples vary up to 24% from the highest quartzite value of 4.04 mm2/s. For all samples, Dlat is lower than that expected for randomly oriented, dry quartz. In quartzites, differences in Dlat between samples decrease with temperature, such that little variation is seen for the β phase. This behavior is expected if porosity, which ranges from 5% to 19%, hinders thermal transport in quartzite. Grain size does not appear to affect Dlat. If water plays an important role in heat transport, we should see it, since quartzite contains much more water than the single crystals. Because of the small number of samples examined, the dual speciation as silanol complexes on grain surfaces of some quartzites (up to 420 H/6 Si) and as molecular water in all samples (ranging from 328 to 5103 H/6 Si

  3. Solar wind control of magnetospheric pressure (CDAW 6)

    NASA Technical Reports Server (NTRS)

    Fairfield, D. H.

    1985-01-01

    The CDAW 6 data base is used to compare solar wind and magnetospheric pressures. The flaring angle of the tail magnetopause is determined by assuming that the component of solar wind pressure normal to the tail boundary is equal to the total pressure within the tail. Results indicate an increase in the tail flaring angle from 18 deg to 32 deg prior to the 1055 substorm onset and a decrease to 25 deg after the onset. This behavior supports the concept of tail energy storage before the substorm and subsequent release after the onset.

  4. Static internal performance of single-expansion-ramp nozzles with thrust-vectoring capability up to 60 deg

    NASA Technical Reports Server (NTRS)

    Berrier, B. L.; Leavitt, L. D.

    1984-01-01

    An investigation has been conducted at static conditions (wind off) in the static-test facility of the Langley 16-Foot Transonic Tunnel. The effects of geometric thrust-vector angle, sidewall containment, ramp curvature, lower-flap lip angle, and ramp length on the internal performance of nonaxisymmetric single-expansion-ramp nozzles were investigated. Geometric thrust-vector angle was varied from -20 deg. to 60 deg., and nozzle pressure ratio was varied from 1.0 (jet off) to approximately 10.0.

  5. Self-reported utilization of mental health services in the adult German population--evidence for unmet needs? Results of the DEGS1-Mental Health Module (DEGS1-MH).

    PubMed

    Mack, Simon; Jacobi, Frank; Gerschler, Anja; Strehle, Jens; Höfler, Michael; Busch, Markus A; Maske, Ulrike E; Hapke, Ulfert; Seiffert, Ingeburg; Gaebel, Wolfgang; Zielasek, Jürgen; Maier, Wolfgang; Wittchen, Hans-Ulrich

    2014-09-01

    This paper provides up-to-date data on service use for mental health problems and disorders among adults aged 18-79 years in Germany derived from the Mental Health Module of the German Health Interview and Examination Survey for Adults (DEGS1-MH; N=4483). Data are based exclusively on self-report. Respondents were examined by clinically trained interviewers with a modified version of the Composite International Diagnostic Interview DIA-X/M-CIDI to assess diagnoses according to the criteria of DSM-IV-TR. Service use, i.e. contact to mental health care services, due to mental health problems was assessed for the past 12 months and lifetime, by type of sector and type of institution. Among respondents with a 12-month diagnosis of a mental disorder, 23.5% of the women and 11.6% of the men reported any service use in the past 12 months. Service use depends on type of diagnosis, comorbidity and socio-demographic characteristics. Lowest 12-month utilization rates were found for substance use disorders (15.6%; lifetime use 37.3%), highest for psychotic disorders (40.5%; lifetime 72.1%). Further, a considerable time lap was found between disorder onset and subsequent service use among the majority of cases with anxiety and mood disorders. This paper provides self-reported epidemiological data on mental health service use in Germany, complementing administrative statistics and the predecessor mental health module of the German Health Interview and Examination Survey (GHS-MHS) from 1998. Despite considerable changes in the mental health field in Germany and the existence of a comprehensive mental health care system without major financial barriers, we find no indications of substantially higher utilization rates for mental disorders as compared to other comparable European countries. Further, no indications of major overall changes in utilization rates are apparent. To pinpoint areas with unmet needs, more detailed analyses of the data are needed taking into account type

  6. Measuring the cosmic microwave background gravitational lensing potential from 500 deg2 of SPTpol data

    NASA Astrophysics Data System (ADS)

    Mocanu, Laura Monica; South Pole Telescope Collaboration

    2016-06-01

    Weak gravitational lensing by large-scale structure in the universe causes deflections in the paths of cosmic microwave background (CMB) photons. This effect introduces non-Gaussian correlations in the observed CMB temperature and polarization fields. The signature of lensing can be used to reconstruct the projected gravitational lensing potential with a quadratic estimator technique; this provides a measure of the integrated mass distribution out to the surface of last scattering, sourced primarily from redshifts between 0.1 and 5. The power spectrum of the lensing potential encodes information about the geometry of the universe and the growth of structure and can be used to place constraints on the sum of neutrino masses and dark energy. High signal-to-noise mass maps from CMB lensing are also powerful for cross-correlating with other tracers of large-scale structure and for delensing the CMB in search for primordial gravitational waves. This poster will describe recent progress on measuring the CMB gravitational lensing potential and its power spectrum using data from 500 deg2 of sky observed with the polarization-sensitive receiver installed on the South Pole Telescope, SPTpol.

  7. Effect of Proton Irradiation on 2DEG in AlGaN/GaN Heterostructures

    NASA Astrophysics Data System (ADS)

    Abderrahmane, A.; Koide, S.; Tahara, T.; Sato, S.; Ohshima, T.; Okada, H.; Sandhu, A.

    2013-04-01

    Low temperature Hall effect measurements were carried on AlGaN/GaN micro-Hall effect sensors before and after irradiation with 380 keV and fluence of 1014 protons/cm2 protons. The sheet electron density after irradiation did not show significant changes but there was a dramatic decrease in the electron mobility of the heterostructures. Prior to irradiation, the observation of well-defined Landau plateaus in the Hall resistance and Shubnikov-de Haas oscillations (SdH) at 4.5 T was indicative of the high quality the heterojunction confining the two-dimensional electron gas (2DEG) at the AlGaN/GaN interface of micro-Hall effect sensors. In contrast, the Landau plateaus disappeared after irradiation and the threshold magnetic field required for the observation of the SdH increased, which was accompanied by a decrease of the electron mobility. Temperature dependent magnetoresistance measurements were used to deduce the effective mass and the quantum scattering time before irradiation. A negative magnetoresistance was observed at low magnetic fields which is related to weak localization and parabolic negative magnetoresistance attributed to electron-electron interaction in both samples.

  8. Comparing the acoustics of voiced and voiceless fricatives in Deg Xinag

    NASA Astrophysics Data System (ADS)

    Wright, Richard; Hargus, Sharon; Miller, Julia

    2005-09-01

    Few studies have looked at the acoustic properties of fricative voicing and place in Native American languages despite their relatively rich fricative inventories of rarely studied fricative places. Deg Xinag, an endangered Athabaskan language spoken in Alaska, provides us with a rare opportunity to investigate fricative place and voicing within a single language: it has eight places of articulation for voiceless fricatives, six of which have voiced counterparts, including some rarely studied place contrasts (e.g., palato-alveolar versus retroflex, uvular versus glottal, lateral versus alveolar). In this study, pre- and post-vocalic fricatives were digitally recorded in the field from eight speakers (two males, six females) using a head-mounted mic to control for distance from the source. The segmental context was also controlled for, the neighboring vowel being [a] in all cases. Each speaker produced four repetitions of each word. Each fricative was analyzed qualitatively using impressionistic transcription and spectrographic investigation, and quantitatively using a set of widely employed measures: (a) widely employed spectral measures (center of gravity, skew, kurtosis, standard deviation, lowest spectral peak), peak and rms intensity of frication, overall duration and duration of voicing. [Work supported by NSF.

  9. Optimisation of artificial neural network structure using Direct Encoding Graph Syntax (DEGS)

    SciTech Connect

    Kothari, B.; Esat, I.

    1996-12-31

    An artificial neural network (ANN) is intended to represent usually a complex non-linear mapping between the two data sets that can then be able to generalize on unseen data for the solution of a particular task. The evaluation of the correct ANN structure (and hence the mapping) is very often, solely a ANN and error procedure which may not lead to the required solution. The Genetic algorithm (GA) has been perceived by researchers as a effective systematic technique for the design of ANNs. However the GA can be hampered by the difficulty of generating a variety of ANN structures. In addition there is the problem of a significant increase of the search space for network architectures as the network size increases (scalability problem). Even if these problems are addressed, the ANN structures produced by the GA must be viable and then efficiently trainable by a competent training algorithm. A network is not viable if it is incomplete with isolated processing units. Also the possibility of encountering the permutation problem which refers to the creation of ANNs that are different in structure but are equivalent geometrically also has to be reduced as this significantly reduces the efficiency of the GA. The above characteristics are indicative of other encoding schemes that poorly encode the ANN. This paper describes a direct encoding scheme, Direct Encoding Graph Syntax (DEGS), that endeavors to overcome these flaws. Its successful implementation in conjunction with the GA, for the design of ANNs to evaluate the 9-bit parity problem is also discussed.

  10. Rabbit retinal neurons and glia express a variety of ENaC/DEG subunits.

    PubMed

    Brockway, L M; Zhou, Z-H; Bubien, J K; Jovov, B; Benos, D J; Keyser, K T

    2002-07-01

    Some members of the epithelial Na+ channel/degenerin (ENaC/DEG) family of ion channels have been detected in mammalian brain. Therefore, we examined the RNA and protein expression of these channels in another part of the central nervous system, the rabbit retina. We next sought to demonstrate physiological evidence for an amiloride-sensitive current in Müller glia, which, on the basis of a previous study, are thought to express alpha-ENaC (Golestaneh N, de Kozak Y, Klein C, and Mirshahi M. Glia 33: 160-168, 2001). RT-PCR of retinal RNA revealed the presence of alpha-, beta-, gamma-, and delta-ENaC as well as acid-sensing ion channel (ASIC)1, ASIC2, ASIC3, and ASIC4. Immunohistochemical localization with antibodies against alpha-ENaC and beta-ENaC showed labeling in Müller cells and neurons, respectively. The presence of alpha-ENaC, beta-ENaC, and ASIC1 was detected by Western blotting. Cultured Müller cells were whole cell patch clamped. These cells exhibited an inward Na+ current that was blocked by amiloride. These data demonstrate for the first time both the expression of a variety of ENaC and ASIC subunits in the rabbit retina as well as distinct cellular expression patterns of specific subunits in neurons and glia. PMID:12055080

  11. A Three-Dimensional CFD Investigation of Secondary Flow in an Accelerating, 90 deg Elbow

    NASA Technical Reports Server (NTRS)

    Cavicchi, Richard H.

    2001-01-01

    NASA Glenn Research Center has recently applied the WIND National Code flow solver to an accelerating elbow with a 90 deg. bend to reveal aspects of secondary flow. This elbow was designed by NACA in the early 1950's such that flow separation would be avoided. Experimental testing was also done at that time. The current three dimensional CFD investigation shows that separation has indeed been avoided. Using its three-dimensional capability, this investigation provides various viewpoints in several planes that display the inception, development, and final location of a passage vortex. Its shape first becomes discernible as a vortex near the exit of the bend. This rendition of the exit passage vortex compares well with that found in the experiments. The viewpoints show that the passage vortex settles on the suction surface at the exit about one-third of the distance between the plane wall and midspan. Furthermore, it projects into the mainstream to about one-third of the channel width. Of several turbulence models used in this investigation, the Spalart Alimaras, Baldwin Lomax, and SST (Shear Stress Transport) models were by far the most successful in matching the experiments.

  12. A Candidate Substellar Companion to CoD -33(deg) 7795 (TWA 5)

    NASA Astrophysics Data System (ADS)

    Lowrance, P. J.; McCarthy, C. M.; Becklin, E. E.; Zuckerman, B.; Schneider, G.; Webb, R. A.; Hines, D. C.; Low, F. J.; Rieke, M. J.; Thompson, R. I.; Smith, B. A.; Meier, R.; Terrile, R. J.; Kirkpatrick, J. D.; Koerner, D. W.

    1998-12-01

    We present the discovery of a candidate substellar object as part of the NICMOS Instrument Design Team's survey of young stars in the solar vicinity using the sensitivity and spatial resolution afforded by the NICMOS coronagraph on the Hubble Space Telescope. The H=12.1 mag object was discovered approximately 2'' from the TW Hydrae Association member CoD -33(deg) 7795 (TWA 5), and the infrared photometry implies a spectral type M8-M8.5, with a temperature of ~ 2650K. We estimate that the probability of a chance alignment with a background object of this nature is < 2 x 10(-5) , and therefore postulate the object (TWA 5B) is physically associated at a projected separation of 100 AU. Given the youth of the primary ( ~ 10 Myr), current brown dwarf cooling models predict a mass of approximately 20 Jupiter masses for the companion. This work is supported in part by NASA grant NAG 5-3042 to the University of Arizona NICMOS Instrument Design Team. This poster is based on observations obtained with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555.

  13. Evolution of oxide scale on a Ni-Mo-Cr alloy at 900 deg. C

    SciTech Connect

    Ul-Hamid, A. . E-mail: anwar@kfupm.edu.sa; Mohammed, A.I.; Al-Jaroudi, S.S.; Tawancy, H.M.; Abbas, N.M.

    2007-01-15

    The cyclic oxidation behavior of a Ni-Mo-Cr alloy was studied in air at 900 deg. C for exposure periods of up to 1000 h. The morphology, microstructure and composition of the oxide scale was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. Oxidation kinetics was determined by weight gain measurements. The results show that steady state oxidation was achieved within 1 h of exposure. During transient oxidation, the alloy grain boundaries intersecting the alloy surface became depleted in Ni and enriched in Mo and Cr. The scale initially formed at the surface was NiO which grew outwardly. However, a protective Cr{sub 2}O{sub 3} layer developed, rapidly retarding the rate of oxidation. Formation of NiMoO{sub 4} was also observed. The presence of Mo in the alloy facilitated the formation of a Cr{sub 2}O{sub 3} layer at an early stage of oxidation. The alloy exhibited considerable oxide spalling during prolonged exposure.

  14. Design and performance of a fixed, nonaccelerating, guide vane cascade that operates over an inlet flow angle range of 60 deg

    NASA Technical Reports Server (NTRS)

    Sanz, J. M.; Mcfarland, E. R.; Sanger, N. L.; Gelder, T. F.; Cavicchi, R. H.

    1984-01-01

    A unique set of wind tunnel guide vanes are designed with an inverse design code and analyzed with a panel method and an integral boundary layer code developed at the NASA Lewis Research Center. The fixed guide vanes, 80 feet long with 6-foot chord length, were designed for the NASA Ames 40 x 80/80 x 120 ft Wind Tunnel. Low subsonic flow is accepted over a 60 deg range of inlet angle from either the 40 x 80 leg or the 80 x 120 leg of the wind tunnel, and directed axially into the main leg of the tunnel where drive fans are located. Experimental tests of 1/10-scale models were conducted to verify design calculations.

  15. Low-speed aerodynamic characteristics of a model having a 42 deg swept low wing with a supercritical airfoil, double-slotted flaps, and a T-tail

    NASA Technical Reports Server (NTRS)

    Fournier, P. G.; Sleeman, W. C., Jr.

    1972-01-01

    A low speed wind tunnel test was conducted in the Langley V/STOL tunnel to determine the static longitudinal and lateral stability characteristics of a general research model which simulated an advance configuration for a commercial transport airplane with a T tail. The model had a 42 deg swept, aspect ratio 6.78 wing with a supercritical airfoil and a high lift system which consisted of a leading edge slat and a double slotted flap. Various slat and flap deflection combinations represented clean, take off, and landing configurations. Effects on the longitudinal and lateral aerodynamic characteristics were determined for two flow through, simulated engine nacelles located on the sides of the fuselage near the rear of the model.

  16. Flow-field surveys on the windward side of the NASA 040A space shuttle orbiter at 31 deg angle of attack and Mach 20 in helium

    NASA Technical Reports Server (NTRS)

    Ashby, G. C., Jr.; Helms, V. T., III

    1977-01-01

    Pitot pressure and flow angle distributions in the windward flow field of the NASA 040A space shuttle orbiter configuration and surface pressures were measured, at a Mach number of 20 and an angle of attack of 31 deg. The free stream Reynolds number, based on model length, was 5.39 x 10 to the 6th power. Results show that cores of high pitot pressure, which are related to the body-shock-wing-shock intersections, occur on the windward plane of symmetry in the vicinity of the wing-body junction and near midspan on the wing. Theoretical estimates of the flow field pitot pressures show that conical flow values for the windward plane of symmetry surface are representative of the average level over the entire lower surface.

  17. Dock leaf beetle, Gastrophysa viridula Deg., herbivory on Mossy Sorrel, Rumex confertus Willd: Induced plant volatiles and beetle orientation responses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The invasive weed Rumex confertus Willd. (mossy sorrel) is fed upon and severely defoliated by Gastrophysa viridula Deg. (dock leaf beetle), a highly promising biological control agent for this weed. We report volatile organic compound (VOC) induction when one leaf on R. confertus was damaged by G. ...

  18. DEG9, a serine protease, modulates cytokinin and light signaling by regulating the level of ARABIDOPSIS RESPONSE REGULATOR 4.

    PubMed

    Chi, Wei; Li, Jing; He, Baoye; Chai, Xin; Xu, Xiumei; Sun, Xuwu; Jiang, Jingjing; Feng, Peiqiang; Zuo, Jianru; Lin, Rongcheng; Rochaix, Jean-David; Zhang, Lixin

    2016-06-21

    Cytokinin is an essential phytohormone that controls various biological processes in plants. A number of response regulators are known to be important for cytokinin signal transduction. ARABIDOPSIS RESPONSE REGULATOR 4 (ARR4) mediates the cross-talk between light and cytokinin signaling through modulation of the activity of phytochrome B. However, the mechanism that regulates the activity and stability of ARR4 is unknown. Here we identify an ATP-independent serine protease, degradation of periplasmic proteins 9 (DEG9), which localizes to the nucleus and regulates the stability of ARR4. Biochemical evidence shows that DEG9 interacts with ARR4, thereby targeting ARR4 for degradation, which suggests that DEG9 regulates the stability of ARR4. Moreover, genetic evidence shows that DEG9 acts upstream of ARR4 and regulates the activity of ARR4 in cytokinin and light-signaling pathways. This study thus identifies a role for a ubiquitin-independent selective protein proteolysis in the regulation of the stability of plant signaling components. PMID:27274065

  19. Complete dipole response in {sup 208}Pb from high-resolution polarized proton scattering at 0 deg

    SciTech Connect

    Neumann-Cosel, P. von; Kalmykov, Y.; Poltoratska, I.; Ponomarev, V. Yu.; Richter, A.; Wambach, J.; Adachi, T.; Fujita, Y.; Matsubara, H.; Sakemi, Y.; Shimizu, Y.; Tameshige, Y.; Yosoi, M.; Bertulani, C. A.; Carter, J.; Fujita, H.; Dozono, M.; Fujita, K.; Hashimoto, H.; Hatanaka, K.

    2009-01-28

    The structure of electric and magnetic dipole modes in {sup 208}Pb is investigated in a high-resolution measurement of the (p-vector,p-vector') reaction under 0 deg. First results on the E1 strength in the region of the pygmy dipole resonance are reported.

  20. A unified mechanism for 2DEG at SrTiO3 /LaAlO3 interface

    NASA Astrophysics Data System (ADS)

    Yu, Liping; Zunger, Alex

    2014-03-01

    The origin of 2DEG appearing at the TiO2-LaO (n-type) interface between two insulating oxides of polar LaAlO3 (LAO) and nonpolar SrTiO3 (STO) after some critical LAO thickness is still under hot debate. Here applying modern defect theory for bulk, interface and surface, based on DFT and HSE, we investigated the current mechanisms that focus on polar catastrophe scenario, interfacial and surface O vacancies (VO), or interfacial cation defects. We uncovered a unified mechanism that can explain not only the 2DEG at n-type interface, but also the insulating behaviour at SrO/AlO2 (p-type) interface. Specifically, for n-type interface, we found that (i) it is the VO at LAO surface coupled with built-in electric field in LAO film that causes 2DEG and determines the critical thickness. (ii) The interfacial La-on-Sr and Ti-on-Al antisite donor defects cause interfacial mixing, but do not contribute itinerant carriers. (iii) The cation vacancies and acceptor antisite defects can trap partially the 2DEG. For p-type interface, the insulating behaviour is resulted from the spontaneous formation of the defect pair of ``interfacial La-on-Sr defect and surface La vacancy defect'' after a critical thickness smaller than that expected from pure polar catastrophe scenario. Supported by DOE BES Energy Frontier Research Center for Inverse Design.