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Sample records for 6 degrees head-down

  1. Orthostatic intolerance in 6 degrees head-down tilt and lower body negative pressure loading

    NASA Astrophysics Data System (ADS)

    Yajima, Kazuyoshi; Miyamoto, Akira; Ito, Masao; Mano, Takaichi; Nakayama, Kiyoshi

    6 degrees head-down tilt bed rest experiment for 6 days was conducted at Nihon University Itabashi Hospital for 10 male athletes. In order to observe the orthostatic intolerance due to six days head-down tilt bed rest, 70 degrees head up tilt tests were performed before and after the head-down tilt. Two types of orthostatic intolerance were distinguished by the time course of their cardiovascular responses. One was vagotonia type and the other was brain anemia type. The latter type was commonly seen among astronauts after space flight due to the lack of plasma volume. As this volume change is considered to be initiated by some fluid loss from the lower extremities, analysis was made to clarify the relation between the leg volume change and the types of orthostatic intolerance. Nakayama proposed a Heart Rate Controllability Index, which is calculated from the initiate leg volume change and heart rate increase in head up tilt, for an indicator of the orthostatic intolerability. The index was applied to the subjects of six days head-down tilt above mentioned. For the subjects who showed a sign of presyncopy, the index values were higher or lower than that of the rest subjects who showed no sign of presyncopy. In order to evaluate the validity of the index, another experiment was conducted to induce an orthostatic intolerance by a different way of loading. The same types of orthostatic intolerance were observed and the index value hit high in the brain anemia type of orthostatic intolerance, while the vagotonia type showed relatively lower values than the normal group.

  2. 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

  3. 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.

  4. 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.

  5. 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).

  6. 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.

  7. Changes in microvascular fluid filtration capacity during 120 days of 6 degrees head-down tilt.

    PubMed

    Christ, F; Gamble, J; Baranov, V; Kotov, A; Chouker, A; Thiel, M; Gartside, I B; Moser, C M; Abicht, J; Messmer, K

    2001-12-01

    We used venous congestion strain gauge plethysmography (VCP) to measure the changes in fluid filtration capacity (K(f)), isovolumetric venous pressure (Pv(i)), and blood flow in six volunteers before, on the 118th day (D118) of head-down tilt (HDT), and 2 days after remobilization (Post). We hypothesized that 120 days of HDT cause significant micro- and macrovascular changes. We observed a significant increase in K(f) from 3.6 +/- 0.4 x 10(-3) to 5.7 +/- 0.9 x 10(-3) ml. min(-1). 100 ml(-1). mmHg(-1) (+51.4%; P < 0.003), which returned to pretilt values (4.0 + 0.4 x 10(-3) ml. min(-1). 100 ml(-1). mmHg(-1)) after remobilization. Similarly, Pv(i) increased from 13.4 +/- 2.1 mmHg to 28.9 +/- 2.8 mmHg (+105.8%; P < 0.001) at D118 and was not significantly different at Post (12.4 +/- 2.6 mmHg). Blood flow decreased significantly from 2.3 +/- 0.3 to 1.3 +/- 0.2 ml. min(-1). 100 ml tissue(-1) at D118 and was found elevated to 3.4 +/- 0.7 ml. min(-1). 100 ml tissue(-1) at Post. We believe that the increased K(f) is caused by a higher microvascular water permeability. Because this may result in edema formation, it could contribute to the alterations in fluid homeostasis after exposure to microgravity.

  8. 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

  9. 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).

  10. 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.

  11. 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.

  12. Effect of centrifuge-induced artificial gravity and ergometric exercise on cardiovascular deconditioning, myatrophy, and osteoporosis induced by a -6 degrees head-down bedrest.

    PubMed

    Iwase, Satoshi; Takada, Hiroki; Watanabe, Yoriko; Ishida, Koji; Akima, Hiroshi; Katayama, Keisho; Iwase, Mitsunori; Hirayanagi, Kaname; Shiozawa, Tomoki; Hamaoka, Takafumi; Masuo, Yoshihisa; Custaud, Marc-Antoine

    2004-07-01

    We have reported that centrifuge-induced artificial gravity with ergometric exercise could reduce developing cardiovascular deconditioning in humans. In the present study, we examined this load could prevent the myatrophy and osteoporosis induced by head-down bedrest for 20 days. Subjects were ten healthy male volunteers with informed consent. They were requested to lie down at -6 degrees for 20 days, and evaluation for cardiovascular deconditioning, myatrophy, and osteoporosis. As the result, high G-load with low intensity exercise suppressed the orthostatic intolerance and increase in serum osteoporotic marker, whereas low G-load with high intensity ergometric exercise maintained the maximal oxygen intake, heart dimension, and prevented myatrophy. The combination of high/low G-load with low/high intensity exercise will determine the optimal protocol for prevention of cardiovascular deconditioning, myatrophy, and osteoporosis.

  13. 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.

  14. 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).

  15. 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.

  16. 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.

  17. 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.

  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. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Increased Brain Activation for Foot Movement During 70-Day 6 Deg Head-Down Bed Rest (HDBR): Evidence from Functional Magnetic Resonance Imaging (fMRI)

    NASA Technical Reports Server (NTRS)

    Yuan, P.; Koppelmans, V.; Cassady, K.; Cooke, K.; De Dios, Y. E.; Stepanyan, V.; Szecsy, D.; Gadd, N.; Wood, S. J.; Reuter-Lorenz, P. A.; Riascos-Castaneda, R.; Kofman, I.; Bloomberg, J. J.; Mulavara, A. P.; Seidler, R. D.

    2015-01-01

    Bed rest has been widely used as a simulation of weightlessness in studying the effects of microgravity exposure on human physiology and cognition. Changes in muscle function and functional mobility have been reported to be associated with bed rest. Understanding the effect of bed rest on neural control of movement would provide helpful information for spaceflight. In the current study, we evaluated how the brain activation for foot movement changed as a function of bed rest. Eighteen healthy men (aged 25 to 39 years) participated in this HDBR study. They remained continuously in the 6deg head-down tilt position for 70 days. Functional MRI was acquired during 1-Hz right foot tapping, and repeated at 7 time points: 12 days pre-, 8 days pre-, 7 days in-, 50 days in-, 70 days in-, 8 days post-, and 12 days post- HDBR. In all 7 sessions, we observed increased activation in the left motor cortex, right cerebellum and right occipital cortex during foot movement blocks compared to rest. Compared to the pre-HDBR baseline (1st and 2nd sessions), foot movement-induced activation in the left hippocampus increased during HDBR. This increase emerged in the 4th session, enlarged in the 5th session, and remained significant in the 6th and 7th sessions. Furthermore, increased activation relative to the baseline in left precuneus was observed in the 5th, 6th and 7th sessions. In addition, in comparison with baseline, increased activation in the left cerebellum was found in the 4th and 5th sessions, whereas increased activation in the right cerebellum was observed in the 4th, 6th and 7th sessions. No brain region exhibited decreased activation during bed rest compared to baseline. The increase of foot movement related brain activation during HDBR suggests that in a long-term head-down position, more neural control is needed to accomplish foot movements. This change required a couple of weeks to develop in HDBR (between 3rd and 4th sessions), and did not return to baseline even 12

  13. 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.

  14. 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

  15. WISE-2005: Adrenergic Responses Before and After 60 Days of 6 Degree Head-Down Bed-Rest in Women

    NASA Technical Reports Server (NTRS)

    Edgell, H.; Dyson, K.; Shoemaker, J. K.; Custaud, M. A.; Arbeille, Ph.; Greaves, D.; Hughson, R. L.; Hughson, R. L.

    2006-01-01

    Sixteen women who participated in the WISE-2005 headdown bed rest (HDBR) were studied before and on day 56 of bed rest to test the hypothesis that chronic changes in circulating norepinephrine (NOR) would change the response to adrenergic receptor agonists. Five minute infusions of 2 doses of isoproterenol (ISO), and 2 doses of NOR were administered while heart rate (HR), mean arterial pressure (MAP) and total peripheral resistance (TPR) were measured. Before HDBR, the higher dose of ISO increased HR by 13 beats/min (P

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. [Evaluation of synthetic antidiuretic hormone as a corrective substance following head-down tilt].

    PubMed

    Noskov, V B; Larina, I M; Nichiporuk, I A; Pastushkova, L Kh; Vasil'eva, G Iu

    2010-01-01

    Effects of synthesized desmopressin, analog of antidiuretic hormone, and water-salt supplement on the renal function and orthostatic stability were studied in 6 normal male subjects after 12-hr. head-down tilt (12 degrees). The combination of water-salt homeostasis normalizing methods was effective in retaining excessive liquid and salts. Moreover, tolerance of the standard 20-min. passive standing test improved significantly. Hence, it was demonstrated that intake of synthetic vasopressin analog combined with WSS counteracted hypohydration of organism due to HDT and improved orthostatic tolerance.

  3. 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.

  4. 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.

  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. 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.

  7. 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.

  8. Echocardiograms during six hours of bedrest at head-down and head-up tilt and during space flight

    NASA Technical Reports Server (NTRS)

    Lathers, C. M.; Riddle, J. M.; Mulvagh, S. L.; Mukai, C.; Diamandis, P. H.; Dussack, L. G.; Bungo, M. W.; Charles, J. B.

    1993-01-01

    Left ventricular end-diastolic volume increased after 4 1/2 to 6 hours of space flight, but was significantly decreased after 5 to 6 days of space flight. To determine the role of acute gravitational effects in this phenomenon, responses to a 6-hour bedrest model of 0 gravity (G; 5 degrees head-down tilt) were compared with those of fractional gravity loads of 1/6 G, 1/3 G, and 2/3 G by using head-up tilts of 10 degrees, 20 degrees, and 42 degrees, respectively. On 4 different days, six healthy male subjects were tilted at one of the four angles for 6 hours. Cardiac dimensions and volumes were determined from two-dimensional and M-mode echocardiograms in the left lateral decubitus position at control (0), 2, 4, and 6 hours. Stroke volume decreased with time (P < .05) for all tilt angles when compared with control. Ejection fraction (EF) at -5 degrees was greater than at +20 degrees and +42 degrees (not significant); EF at +10 degrees was greater than at +42 degrees (not significant). For the tilt angles of -5 degrees, +10 degrees, and +20 degrees, mean heart rate decreased during the first 2 hours, and returned to control or was slightly elevated above control (+20 degrees) by 6 hours (not significant). At the +42 degrees angle of tilt, heart rate was increased above control at hours 2, 4, and 6. There were no significant differences in cardiac output at any time point for any tilt angle.(ABSTRACT TRUNCATED AT 250 WORDS).

  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. 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.

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

    PubMed

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

    1993-04-01

    To determine the effects of hypoxia on physiological responses to simulated zero-gravity, cardiopulmonary and fluid balance measurements were made in 6 subjects (acclimatized to 5,400 ft) before and during 5 degrees head-down bed rest (HDBR) over 8 d at 10,678 ft and a second time at this altitude as controls (CON). The VO2max increased by 9% after CON, but fell 3% after HDBR (p < 0.05). 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.

  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 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.

  14. 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

  15. Intraocular pressure, retinal vascular, and visual acuity changes during 48 hours of 10-deg head-down tilt

    NASA Technical Reports Server (NTRS)

    Mader, Thomas H.; Taylor, Gerald R.; Hunter, Norwood; Caputo, Michael; Meehan, Richard T.

    1990-01-01

    Intraocular pressures, retinal vascular diameters, and visual acuities of nine men, were repeatedly measured while the subjects were tilted 10 deg head-down for 48 h and while they were seated before (baseline), and after the tilt. An immediate increase in intraocular pressure, measured by pneumatonometer was recorded when subjects assumed the head-down position, and diurnal variations in intraocular pressures were observed for the 48 h. The initial and final head-down intraocular pressures were not significantly different. However, when subjects resumed the sitting position, intraocular pressures fell below the initial sitting values. Computer image analysis of the retinal vasculature detected a 6 percent and 2 percent reduction in the caliber of arteries and veins, respectively, as compared with sitting baseline values. No changes in visual acuity were documented during the 48 h of head-down tilt. The data suggest that the choroidal blood reservoir increases in volume over 48 h at continuous head-down position with a compensatory decrease in aqueous volume. These findings may explain intraocular pressure changes noted in astronauts during previous space missions and in studies associated with change in body position.

  16. 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.

  17. Pathway concepts experiment for head-down synthetic vision displays

    NASA Astrophysics Data System (ADS)

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

    2004-08-01

    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.

  18. AMLCD head-down displays for avionic applications

    NASA Astrophysics Data System (ADS)

    Davis, Alan J.

    1997-02-01

    Smiths Industries has been involved in the design, manufacture and supply of products used for the presentation of information, in one form or another, from its early pioneering years through to the present day. In the mid 1980s Smiths Industries began to invest in the then emerging active matrix liquid crystal display (AMLCD) technology which the company believed would eventually take over from the cathode ray tube. To date Smiths Industries has made a significant investment in acquiring the enabling technology needed to produce active matrix liquid crystal color head- down displays for fast jet, helicopter and civil aircraft applications. The significant improvement in AMLCD product quality and manufacturing capability over recent years has enabled market penetration of AMLCD technology products to be achieved in military and civil avionic markets. Virtually all new contracts for head-down displays are now demanding the use of AMLCD technology rather than the cathode ray tube. A significant decision to move to AMLCD technology was made by McDonnell Douglas Helicopters in 1995, when a contract to supply over 4000 head-down display products for the Apache Helicopter was let. This has paved the way for the future of AMLCD technology.

  19. Effects of head-down tilt on the intracranial pressure in conscious rabbits.

    PubMed

    Tatebayashi, Kyoko; Asai, Yasumasa; Maeda, Tomoyuki; Shiraishi, Yoshimitsu; Miyoshi, Michio; Kawai, Yasuaki

    2003-07-04

    Head-down tilt (HDT) causes a fluid shift towards the upper body, which increases intracranial pressure (ICP). In the present study, the time course of ICP changes during prolonged exposure to HDT was investigated in conscious rabbits through a catheter chronically implanted into the subarachnoid space. The production of cerebrospinal fluid (CSF) after exposure to 7-days HDT was also examined by a ventriculo-cisternal perfusion method. The ICP increased from 4.3+/-0.4 (mean+/-S.E.M.) mmHg to 8.0+/-0.8 mmHg immediately after the onset of 45 degrees HDT, reached a peak value of 15.8+/-1.9 mmHg at 11 h, and then decreased to 10.4+/-1.1 mmHg at 24 h. During 7-days HDT, it also increased from 4.8+/-0.9 mmHg to 9.2+/-1.6 mmHg immediately after the onset of 45 degrees HDT, reached a peak value of 12.8+/-2.5 mmHg at 12 h of HDT, and then decreased gradually towards the pre-HDT baseline value for 7 days. The rate of CSF production was 10.1+/-0.6 microl/min in rabbits exposed to 7-days HDT, and 9.7+/-0.5 microl/min in control rabbits. These results suggest that the rabbits begin to adapt to HDT within a few days and that the production of CSF is preserved after exposure to 7-days HDT. The time course of ICP changes during HDT in conscious rabbits seems to be considerably different from that in anesthetized rabbits.

  20. LBNP/ergometer effects on female cardiovascular and muscle deconditioning in 15d head-down bed rest

    NASA Astrophysics Data System (ADS)

    Wang, Lin-Jie

    2012-07-01

    Female has already been an important part of astronaut corps but gender characteristics in weightlessness and countermeasure effects still not clearly elucidated. In this study the LBNP/Ergometer effects on female cardiovascular deconditioning and muscle atrophy in 15d head-down bed rest were explored. 22 female university students were recruited as volunteers that participated in the 15d head-down bed rest. They were divided into control group (Con,n=8), LBNP exercise group (LBNP,n=7) and LBNP combined with ergometer exercise group (LBNP+Ergo, n=7). Grade negative pressures of -10,-20,-30,-40mmHg 20 or 55min were used in LBNP exercise. In ergometer exercises the subjects must maintain 60-80% VO2peak of pre-bed rest at pedal speed of about 70cycle/min for 15min and the entire exercise duration was 30min. LBNP were performed at 6th,8th,10th,12th,and 13th day and Ergometer were operated at 4th,5th,7th,9th,11th day during bed rest. Before and after bed rest, cardiovascular tilt test were performed to evaluate orthostatic intolerance, supine cycle ergometer were used to test the cardiopulmonary function, MRI tests were operated to examine the volume variations of leg muscle groups and isokinetic test were given to test the muscle strength and endurance of knee. 40% of female subjects did not pass the tilt table test after bed rest and exercises made no difference. Compared with pre-BR, VO2max and VO2max /body weight, VO2/HRmax, maximal power and duration significantly decreased in CON group and LBNP group. For the ERGO+LBNP group, there were no visible different in the parameters of cardiopulmonary function except that maximal power and duration decreased. Muscle maximal voluntary contraction and muscle (quadriceps, rectus femoris, gastrocnemius and soleus) volume decreasing in non-predominant leg was larger in Con group than in LBNP+Ergo group. It is suggested that LBNP combined with ergometer in some degrees can counteract the cardiovascular and muscle deconditioning

  1. 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.

  2. 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.

  3. Cerebral haemodynamic response to acute intracranial hypertension induced by head-down tilt.

    PubMed

    Bosone, Daniele; Ozturk, Vesile; Roatta, Silvestro; Cavallini, Anna; Tosi, Piera; Micieli, Giuseppe

    2004-01-01

    The aim of this study was to evaluate, in a context of general inhibition of the sympathetic nervous system, the cerebral haemodynamic response to -30 degrees head-down tilt (HDT), a manoeuvre that produces an increase in intracranial arterial pressure. Nineteen healthy subjects were studied according to the following protocol: 10 min lying in supine position, 10 min HDT, 10 min recovery. Inhibition of the sympathetic system was confirmed by the decrease in heart rate (-3.6 bpm) and arterial blood pressure (-5.9 mmHg, p<0.05) in the late phase of the test. Blood velocity and blood pusatility index initially increased (+3.2 cm s(-1) and +9% respectively, p<0.01) then returned towards baseline before the end of HDT, while the cerebrovascular resistance index (=arterial blood pressure/blood velocity) dropped significantly and remained below control level (-7%, p<0.01) throughout the test. The changes in both these indices were opposite to those reported in several sympathetic activation tests, such as the handgrip and cold pressor tests. Conversely, arterial pressure at cranial level increased during HDT (as it also does during sympathetic activation tests), due to the development of a hydrostatic pressure gradient between heart and brain levels. Therefore, the effects observed on the pulsatility and resistance indices are not secondary to the increase in intracranial arterial pressure. It is suggested that the changes in these cerebrovascular indices are mediated by a reduction of sympathetic tone that presumably involves the cerebral as well as the peripheral vascular bed.

  4. 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.

  5. 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

  6. Early cardiovascular adaptation to zero gravity simulated by head-down tilt

    NASA Technical Reports Server (NTRS)

    Blomqvist, C. G.; Nixon, J. V.; Johnson, R. L., Jr.; Mitchell, J. H.

    1979-01-01

    The early cardiovascular adaptation to zero gravity, simulated by head-down tilt at 5 deg, was studied in a series of 10 normal young men. The validity of the model was confirmed by comparing the results with data from Apollo and Skylab flights. Tilt produced a significant central fluid shift with a transient increase in central venous pressure, later followed by an increase in left ventricular size without changes in cardiac output, arterial pressure, or contractile state. The hemodynamic changes were transient with a nearly complete return to the control state within 6 h. The adaptation included a diuresis and a decrease in blood volume, associated with ADH, renin, and aldosterone inhibition.

  7. Effects of head-down tilt on fluid and electrolyte balance

    NASA Technical Reports Server (NTRS)

    Volicer, L.; Jean-Charles, R.; Chobanian, A. V.

    1976-01-01

    The metabolic effects of -5 deg tilt were studied in eight normal individuals. Exposure to tilt for 24 hr increased sodium excretion and decreased plasma volume. Plasma renin activity and plasma aldosterone levels were not significantly different from supine values during the first 6 hr of tilting, but were increased significantly at the end of the 24-hr tilt period. Creatinine clearance and potassium balance were not affected by the tilt. These findings indicate that head-down tilt induces a sodium diuresis and stimulation of the renin-angiotensin-aldosterone system.

  8. 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.

  9. 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.

  10. Analysis of Retinal Vascular Branching in Human Subjects Undergoing 70-Day Head-Down Tilt by NASAs VESGEN Software

    NASA Technical Reports Server (NTRS)

    Parsons-Wingerter, Patricia; Vyas, Ruchi J.; Raghunandan, Sneha; Vu, Amanda C.; Zanello, Susana B.; Ploutz-Snyder, Rob; Taibbi, Giovanni; Vizzeri, Gianmarco

    2016-01-01

    Significant risks for visual impairment were discovered recently in astronauts following spaceflight, especially after long-duration missions. We hypothesize that microgravity-induced fluid shifts result in pathological changes within the retinal vasculature that precede visual and other ocular impairments. We therefore are analyzing retinal vessels in healthy subjects before and after head-down tilt (HDT), a ground-based microgravity analog with NASA's VESsel GENeration Analysis (VESGEN) software. Methods. Spectralis® infrared (IR) fundus images were collected from both eyes of 6 subjects before and after 70 days of bed rest at 6 degree HDT (NASA Campaign 11). For our retrospective study, branching patterns in arterial and venous trees are mapped by VESGEN into vessel branching generations (Gx) that are quantified by parameters such as densities of vessel length (Lv), area (Av), number (Nv) and fractal dimension (Df) as described previously for diabetic retinopathy (IOVS 51(1):498). Results are further assigned by VESGEN into groups of large (G1-3), medium (G4-6) and small (G=7) vessels. Results. All subjects remained asymptomatic throughout duration of HDT. To date, we have analyzed one IR image from each of the 12 eyes. Interestingly, two groups of the masked study population identified by VESGEN are distinguished by the presence or absence of small veins (G=7). For example, L=7 and Av=7 are 2.7+/-1.3 E-4 px/px2 and 7.2+/-3.6 E-4 px2/px2 in 6 retinas, but 0 in the other 6 retinas. Nonetheless, the space-filling properties of the entire venous trees were remarkably uniform by all parameters, such as Df = 1.56+/-0.02 for 6 retinas with G=7 and 1.55+/-0.02 for retinas without G=7. No small arteries (G=7) were detected. Conclusions. For our preliminary masked analysis, two groups of venous trees with and without small veins (G=7) were clearly revealed by VESGEN. Upon completing all images and unmasking the subject status of before and after HDT, we will determine

  11. Effects of head down tilt upon cortisol and sex hormones

    NASA Astrophysics Data System (ADS)

    Strollo, Felice; Pecorelli, Lia; Uva, Bianca Maria; Masini, Maria Angela; More, Massimo; Strollo, Giovanna; Riondino, Giuseppe

    2005-08-01

    Real and modelled μG conditions seem to induce reversible testicular failure. Suitable onground simulation methods are anyway needed in order to better aim further studies in humans in space. A 5- hour head down tilt (5h-HDT) was therefore performed in 22 male and female healthy volunteers looking at adrenal and gonadal hormones as compared to 12 age- and gender- matched controls. Cortisol and A decreased significantly in both genders, being cortisol decrease less pronounced in women, while leptin, LH, testosterone, estradiol and estrone failed to do so. The authors conclude that a 5h-HDT is only acceptable for adrenal adaptation studies whole longer duration HDT protocols are needed for gonadal investigations.

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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).

  3. 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.

  4. Changes in endotracheal tube cuff pressure during laparoscopic surgery in head-up or head-down position

    PubMed Central

    2014-01-01

    Background The abdominal insufflation and surgical positioning in the laparoscopic surgery have been reported to result in an increase of airway pressure. However, associated effects on changes of endotracheal tube cuff pressure are not well established. Methods 70 patients undergoing elective laparoscopic colorectal tumor resection (head-down position, n = 38) and laparoscopic cholecystecomy (head-up position, n = 32) were enrolled and were compared to 15 patients undergoing elective open abdominal surgery. Changes of cuff and airway pressures before and after abdominal insufflation in supine position and after head-down or head-up positioning were analysed and compared. Results There was no significant cuff and airway pressure changes during the first fifteen minutes in open abdominal surgery. After insufflation, the cuff pressure increased from 26 ± 3 to 32 ± 6 and 27 ± 3 to 33 ± 5 cmH2O in patients receiving laparoscopic cholecystecomy and laparoscopic colorectal tumor resection respectively (both p < 0.001). The head-down tilt further increased cuff pressure from 33 ± 5 to 35 ± 5 cmH2O (p < 0.001). There six patients undergoing colorectal tumor resection (18.8%) and eight patients undergoing cholecystecomy (21.1%) had a total increase of cuff pressure more than 10 cm H2O (18.8%). There was no significant correlation between increase of cuff pressure and either the patient's body mass index or the common range of intra-abdominal pressure (10-15 mmHg) used in laparoscopic surgery. Conclusions An increase of endotracheal tube cuff pressure may occur during laparoscopic surgery especially in the head-down position. PMID:25210501

  5. 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

  6. 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

  7. 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

  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. 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).

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. Cardiovascular Differences after 4 Hours of Head-Down Bed Rest (HDBR) in Men and Women

    NASA Astrophysics Data System (ADS)

    Edgell, Heather; Grinberg, Anna; Beavers, Keith; Gagne, Nathalie; Geaves, Danielle; Hughson, Richard

    2008-06-01

    In both sexes, orthostatic responses are impaired by spaceflight or head-down bed-rest (HDBR), with a greater impact in women. We measured heart rate (HR), mean arterial blood pressure (MAP), cardiac output (Q), stroke volume (SV), central venous pressure (CVP), and total peripheral resistance (TPR) in response to lower body negative pressure (LBNP) in men (n=6) and women (n=6; day 8-11 after menstruation) before and after 4-hr HDBR or seated control (SEAT). Women exhibit lower MAP and TPR with higher SV and Q than men (normalized for body size). LBNP increased HR, decreased CVP, decreased SV, increased TPR and decreased Q. In women 4-hr SEAT results in lower CVP (P=0.015). After 4 hr HDBR men and women exhibit: 1) higher HR response (P<0.001), 2) lower resting CVP (P=0.001), 3) a tendency for higher resting Q (p=0.061). Our results indicate that inactivity and/or circadian rhythm may be important factors to consider when studying women.

  15. Choroidal readaptation to gravity in rats after spaceflight and head-down tilt.

    PubMed

    Davet, J; Clavel, B; Datas, L; Mani-Ponset, L; Maurel, D; Herbuté, S; Viso, M; Hinds, W; Jarvi, J; Gabrion, J

    1998-01-01

    To determine when choroidal structures were restored after readaptation to Earth gravity or orthostatic position, fine structure and protein distribution were studied in rat choroid plexus dissected either 6 h [Space Life Sciences-2 (SLS-2) experiments] or 2 days [National Institutes of Health-Rodent 1 (NIH-R1) experiments] after a spaceflight, or 6 h after head-down tilt (HDT) experiments. Apical alterations were noted in choroidal cells from SLS-2 and HDT animals, confirming that weightlessness impaired choroidal structures and functions. However, the presence of small apical microvilli and kinocilia and the absence of vesicle accumulations showed that the apical organization began to be restored rapidly after landing. Very enlarged apical microvilli appeared after 2 days on Earth, suggesting increased choroidal activity. However, as distributions of ezrin and carbonic anhydrase II remained altered in both flight and suspended animals after readaptation to Earth gravity, it was concluded that choroidal structures and functions were not completely restored, even after 2 days in Earth's gravity.

  16. Sympathetic nervous activity decreases during head down bed rest but not during microgravity

    NASA Astrophysics Data System (ADS)

    Christensen, Niels J.; Heer, Martina; Ivanova, Krassimira; Norsk, Peter

    2007-09-01

    Platelet norepinephrine (NE) and epinephrine (E) were measured as indices of long-term changes in sympathoadrenal activity. Ten normal healthy subjects were studied before and during head-down bed rest (HDBR) of 2 weeks duration, as well as during an ambulatory study period of a similar length. Platelet NE and E concentrations were studied in 5 cosmonauts, who participated in three different Soyuz missions to the International Space Station, 2 weeks before launch, within 12 hours after landing following 11 to 12 days of flight and at least 2 weeks after return to earth. Due to the long half-life of NE and E in platelets (approximately 2 days), data obtained early after landing would still reflect the microgravity state. Platelet NE decreased markedly during HDBR (p<0.001). During micro-gravity platelet NE and E increased in 4 of the 5 cosmonauts. Platelet NE and E concentrations expressed in percentage of pre-flight and pre-HDBR values, respectively, were significantly increased during microgravity as compared to HDBR (NE: 153±28% (mean±SEM) vs. 60±6%, p<0.004; E: 293±85% vs. 90±12%, p<0.01). The increase in platelet NE and E during microgravity is most likely due to an increase in sympathoadrenal activity. The reason why sympathoadrenal activity does not decrease to low levels during microgravity as one would expect remains to be elucidated. HDBR cannot be applied to simulate changes in sympathoadrenal activity during microgravity.

  17. 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

  18. Comparison of physiological effects of head-down tilting and immersion on the human body.

    PubMed

    Shulzhenko, E B; Panfilov, V E; Gogolev, K I; Aleksandrova, E A

    1979-10-01

    Among the methods simulating weightlessness, effects on the human body, head-down tilting and water immersion are very useful. The purpose of the present investigation was to carry out a comparative study of water balance and water-protein composition of the blood using the above two methods to simulate the physiological effects typical of an acute stage of weightlessness adaptation. The results of the 7-d head-down tilting and immersion experiments allow the following conclusions: More pronounced changes in water balance and water-protein composition of the blood during immersion seem to indicate that immersion produces a greater effect on the human body; The pattern of changes during immersion and tilting suggests that the adaptation period to immersion takes a longer time; These findings give evidence that immersion, compared with head-down tilting, reproduces more closely effects of acute adaptation to simulated weightlessness.

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. Orthostatic function during a stand test before and after head-up or head-down bedrest

    NASA Technical Reports Server (NTRS)

    Lathers, Claire M.; Diamandis, Peter H.; Riddle, Jeanne M.; Mukai, Chiaki; Elton, Kay F.; Bungo, Michael W.; Charles, John B.

    1991-01-01

    The effects of head-down or head-up bedrest at -5, +10, +20, or +42 deg (simulating 0, 1/6, 1/3, and 2/3 g, respectively) for 6 hrs on four different days on the orthostatic tolerance were investigated by measuring relevant physiological reactions to orthostatic test taken before and after bedrest sessions. The multivariate analysis of variance statistical analyses indicates that there was no angle effect on any of the cardiovascular parameters monitored during the last 3 min of the stand test, suggesting that partial gravity loads would have no effect on the cardiovascular deconditioning exhibited postflight. There was, however, a significant elevation in the heart rate post-bedrest, and the heart rate increased on standing. Results from the stand test pre- and post-bedrest at -5 deg (but not at +10, +20, and +42 deg) were similar to those observed after space flight.

  9. Effects of Head-down Tilt on Nerve Conduction in Rhesus Monkeys

    PubMed Central

    Sun, Bo; Zhang, Xiao-Yun; Liu, Li-Zhi; Chen, Zhao-Hui; Dai, Zhong-Quan; Huang, Xu-Sheng

    2017-01-01

    Background: Few studies have focused on peripheral nerve conduction during exposure to microgravity. The −6° head-down tilt (HDT) comprises an experimental model used to simulate the space flight environment. This study investigated nerve conduction characteristics of rhesus monkeys before and after prolonged exposure to HDT. Methods: Six rhesus monkeys (3–4 years old) were tilted backward 6° from the horizontal. Nerve conduction studies (NCSs) were performed on the median, ulnar, tibial, and fibular motor nerves. Analysis of variance with a randomized block design was conducted to compare the differences in the NCS before and 7, 21, and 42 days after the −6° HDT. Results: The proximal amplitude of the CMAP of the median nerve was significantly decreased at 21 and 42 days of HDT compared with the amplitude before HDT (4.38 ± 2.83 vs. 8.40 ± 2.66 mV, F = 4.85, P = 0.013 and 3.30 ± 2.70 vs. 8.40 ± 2.66 mV, F = 5.93, P = 0.004, respectively). The distal amplitude of the CMAP of the median nerve was significantly decreased at 7, 21, and 42 days of HDT compared with the amplitude before HDT (7.28 ± 1.27 vs. 10.25 ± 3.40 mV, F = 4.03, P = 0.039; 5.05 ± 2.01 vs. 10.25 ± 3.40 mV, F = 6.25, P = 0.04; and 3.95 ± 2.79 vs. 10.25 ± 3.40 mV, F = 7.35, P = 0.01; respectively). The proximal amplitude of the CMAP of the tibial nerve was significantly decreased at 42 days of HDT compared with the amplitude before HDT (6.14 ± 1.94 vs. 11.87 ± 3.19 mV, F = 5.02, P = 0.039). Conclusions: This study demonstrates that the compound muscle action potential amplitudes of nerves are decreased under simulated microgravity in rhesus monkeys. Moreover, rhesus monkeys exposed to HDT might be served as an experimental model for the study of NCS under microgravity. PMID:28139516

  10. 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.

  11. 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

  12. 21 CFR 888.6 - Degree of constraint.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... ORTHOPEDIC DEVICES General Provisions § 888.6 Degree of constraint. Certain joint prostheses provide more... affecting the safety and effectiveness of orthopedic prostheses. FDA is defining the following standard terms for categorizing the degree of constraint. (a) A “constrained” joint prosthesis is used for...

  13. 21 CFR 888.6 - Degree of constraint.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... ORTHOPEDIC DEVICES General Provisions § 888.6 Degree of constraint. Certain joint prostheses provide more... affecting the safety and effectiveness of orthopedic prostheses. FDA is defining the following standard terms for categorizing the degree of constraint. (a) A “constrained” joint prosthesis is used for...

  14. 21 CFR 888.6 - Degree of constraint.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... ORTHOPEDIC DEVICES General Provisions § 888.6 Degree of constraint. Certain joint prostheses provide more... affecting the safety and effectiveness of orthopedic prostheses. FDA is defining the following standard terms for categorizing the degree of constraint. (a) A “constrained” joint prosthesis is used for...

  15. 21 CFR 888.6 - Degree of constraint.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... ORTHOPEDIC DEVICES General Provisions § 888.6 Degree of constraint. Certain joint prostheses provide more... affecting the safety and effectiveness of orthopedic prostheses. FDA is defining the following standard terms for categorizing the degree of constraint. (a) A “constrained” joint prosthesis is used for...

  16. 21 CFR 888.6 - Degree of constraint.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... ORTHOPEDIC DEVICES General Provisions § 888.6 Degree of constraint. Certain joint prostheses provide more... affecting the safety and effectiveness of orthopedic prostheses. FDA is defining the following standard terms for categorizing the degree of constraint. (a) A “constrained” joint prosthesis is used for...

  17. 6. SITE OVERVIEW, LOOKING 42 DEGREES NORTHEAST. PART TWO OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. SITE OVERVIEW, LOOKING 42 DEGREES NORTHEAST. PART TWO OF THREE-PART PANORAMA. FROM LEFT TO RIGHT: BUNKHOUSE, HAY BARN, GRANARY. - Hudson-Cippa-Wolf Ranch, Sorento Road, Sacramento, Sacramento County, CA

  18. 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.

  19. 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.

  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. 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

  2. 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.

  3. Using Ultrasonography to Determine Optimal Head-down Tilt Position Angle in Patients before Catheterization of the Internal Jugular Vein

    PubMed Central

    Kasatkin, Anton A.; Urakov, Aleksandr L.; Nigmatullina, Anna R.

    2017-01-01

    Context: It is believed that 15°–25° head-down tilt position increases the internal jugular vein cross-sectional area (IJV CSA). The increase in IJV CSA before puncture reduces the risk of its perforation. This pattern was not observed in all patients. We assumed that the absence of respiratory-based IJV excursion is one of the criteria of head-down tilt position effectiveness. Aims: The aim of this study is to determine the head-down tilt angle, which ensures the absence of the respiratory-based IJV excursion. Subjects and Methods: Prospective study included twenty adult patients. The IJVs scanning was carried out in 1 min after placing the patients in a horizontal position on their back and in 1 min after placing them in the head-down tilt position at 5°, 10°, 15°, and 20° tilt angles. Results: We found that collapsibility index of <9% indicating the absence of respiratory-based IJV excursion was recorded in 25% of patients in the horizontal supine position. In this case, placing the patients in the Trendelenburg position for IJV catheterization may not be indicated. In 65% of the patients, the respiratory-based excursion was not observed at 10° head-down tilt position. Only 35% of the patients required 15° head-down tilt position. Conclusions: In clinical settings, the disappearance of respiratory-based vein excursion on the ultrasound scanner screen can be considered as criteria of the head-down tilt position effectiveness.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. [The red blood system in men during long-term head-down bed rest].

    PubMed

    Ivanova, S M; Morukov, B V; Iarlykova, Iu V; Labetskaia, O I; Levina, A A; Kozinets, G I

    2005-01-01

    Red blood was analyzed in six 25 to 40 yr. old male volunteers in a 120-d head-down bedrest (HDBR) study. The hematological investigation included morphological analyses (erythrocyte count and hemoglobin), and determination of iron turnover, erythrocyte IgA, IgG and IgM, metabolism, lipids and phospholipids, and lipid peroxidation rate (LPO). At the beginning of HDBR (day 7), the erythrocyte count and hemoglobin content were found increased w/o any visible changes in the other parameters. Further exposure to HDBR (days 50-100) resulted in modification of intracellular metabolism in erythrocytes, increases in serum iron, and serum and erythrocyte ferritin. On HDBR days 50 and 100, and post-HDBR day 9, cholesterol was increased, LPO intensified and antioxidant activities inhibited, which suggested destabilization of the cell membrane. Hematological shifts in the bedrested volunteers were of the type and pattern similar to those in cosmonauts who fulfilled extended space missions.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. Quaternary geologic map of the Sudbury 4 degree by 6 degree quadrangle, United States and Canada

    USGS Publications Warehouse

    Fullerton, David S.; Sado, Edward V.; Baker, C.L.; Farrand, William R.

    2004-01-01

    The Quaternary Geologic Map of the Sudbury 4 degrees x 6 degrees Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

  18. Quaternary geologic map of the Chicago 4 degrees x 6 degrees quadrangle, United States

    USGS Publications Warehouse

    State compilations by Lineback, Jerry A.; Bleuer, Ned K.; Mickelson, David M.; Farrand, William R.; Goldthwait, Richard P.; Edited and integrated by Richmond, Gerald M.; Fullerton, David S.

    1983-01-01

    The Quaternary Geologic Map of the Chicago 4 degree x 6 degree Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

  19. 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

  20. A short term -12° head down tilt does not mimic microgravity in terms of human gonadal function

    NASA Astrophysics Data System (ADS)

    Strollo, Felice; Pecorelli, Lia; Strollo, Giovanna; Morè, Massimo; Riondino, Giuseppe; Masini, Maria Angela; Uva, Bianca Maria

    2006-09-01

    A significant reversible decrease in testosterone (T) has been associated with microgravity in male rodents and humans. Urinary T excretion increases in primates under hypergravity. Hypogonadism is somehow related to abnormally high levels of leptin (L), a hormone produced by the adipose tissue which has been found to increase under microgravity simulation conditions like head down bed rest (HDBR). The aim of this study was to assess hemodynamic and pituitary-adrenal and -gonadal adaptation to an acute HDBR test to be eventually used on a routine basis to get better prepared to next space flights. The Authors performed a 1 hour -12° HDBR in 6 male and 6 female volunteers who underwent heart rate and blood pressure measurement together with a blood draw three times at 30 min intervals from the start to the end of the test for L, T, estradiol (E2), LH, androstenedione (A), cortisol (F), ACTH. 12 age- and sexmatched control subjects followed the same protocol except for keeping the sitting position all the time. According to the ANOVA for repeated measures, no changes occurred in L, T, E2 or LH whereas A, F and ACTH significantly decreased independently of gender. During HDBR systolic blood pressure decreased in both genders, diastolic blood pressure decreased significantly only in men and HR showed a more clear-cut decrease in women than in men. As a conclusion, such an acute steep-slope HDBR protocol may be efficiently used to testing immediate individual haemodynamic or adrenal response to microgravity but is not suitable for studies concerning gonadal adaptation.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Quaternary Geologic Map of the Platte River 4 Degrees x 6 Degrees Quadrangle, United States

    USGS Publications Warehouse

    Swinehart, James B.; Dreeszen, Vincent H.; Richmond, Gerald Martin; Tipton, Merlin J.; Bretz, Richard F.; Steece, Fred V.; Hallberg, George R.; Goebel, Joseph E.; edited and integrated by Richmond, Gerald Martin

    1994-01-01

    The Quaternary Geologic Map of the Platte River 4 degree x 6 degree Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale. This map is part of the Quaternary Geologic Atlas of the United States (I-1420). It was first published as a printed edition in 1994. The geologic data have now been captured digitally and are presented here along with images of the printed map sheet and component parts as PDF files.

  9. Quaternary Geologic Map of the Des Moines 4 Degrees x 6 Degrees Quadrangle, United States

    USGS Publications Warehouse

    Hallberg, George R.; Lineback, Jerry A.; Mickelson, David M.; Knox, James C.; Goebel, Joseph E.; Hobbs, Howard C.; Whitfield, John W.; Ward, Ronald A.; Boellstorff, John D.; Swinehart, James B.; Dreeszen, Vincent H.; edited and integrated by Richmond, Gerald Martin; Fullerton, David S.; Christiansen, Ann Coe

    1994-01-01

    The Quaternary Geologic Map of the Des Moines 4 degree x 6 degree Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale. This map is part of the Quaternary Geologic Atlas of the United States (I-1420). It was first published as a printed edition in 1994. The geologic data have now been captured digitally and are presented here along with images of the printed map sheet and component parts as PDF files.

  10. Quaternary geologic map of the Monterrey 4 degrees x 6 degrees quadrangle, United States

    USGS Publications Warehouse

    Moore, David W.; Wermund, E.G.; edited and integrated by Moore, David W.; Richmond, Gerald Martin

    1993-01-01

    This map is part of the Quaternary Geologic Atlas of the United States (I-1420). It was first published as a printed edition in 1993. The geologic data have now been captured digitally and are presented here along with images of the printed map sheet and component parts as PDF files. The Quaternary Geologic Map of the Monterrey 4 degrees x 6 degrees Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the Earth. They make up the ground on which we walk, the dirt in which we dig foundations, and the soil in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale. In recent years, surficial deposits and materials have become the focus of much interest by scientists, environmentalists, governmental agencies, and the general public. They are the foundations of ecosystems, the materials that support plant growth and animal habitat, and the materials through which travels much of the water required for our agriculture, our industry, and our general well being. They also are materials that easily can become contaminated by pesticides, fertilizers, and toxic wastes. In this context, the value of the surficial geologic map is evident.

  11. Quaternary geologic map of the Mobile 4 degrees x 6 degrees quadrangle, United States

    USGS Publications Warehouse

    State compilations by Copeland, Charles W.; Rheams, K.F.; Neathery, T.L.; Gilliland, W.A.; Schmidt, Walter; Clark, W.C.; Pope, D.E.; edited and integrated by Richmond, Gerald Martin; Fullerton, David S.; Weide, David L.; Digital database by Bush, Charles A.

    1988-01-01

    This map is part of the Quaternary Geologic Atlas of the United States (I-1420). It was first published as a printed edition in 1988. The geologic data have now been captured digitally and are presented here along with images of the printed map sheet and component parts as PDF files. The Quaternary Geologic Map of the Mobile 4 degrees x 6 degrees Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the Earth. They make up the ground on which we walk, the dirt in which we dig foundations, and the soil in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale. In recent years, surficial deposits and materials have become the focus of much interest by scientists, environmentalists, governmental agencies, and the general public. They are the foundations of ecosystems, the materials that support plant growth and animal habitat, and the materials through which travels much of the water required for our agriculture, our industry, and our general well being. They also are materials that easily can become contaminated by pesticides, fertilizers, and toxic wastes. In this context, the value of the surficial geologic map

  12. Quaternary geologic map of the Jacksonville 4 degrees x 6 degrees quadrangle, United States

    USGS Publications Warehouse

    State compilations by Scott, Thomas M.; Knapp, M.S.; Friddell, M.S.; Weide, David L.; edited and integrated by Richmond, Gerald Martin; Fullerton, David S.

    1986-01-01

    This map is part of the Quaternary Geologic Atlas of the United States (I-1420). It was first published as a printed edition in 1986. The geologic data have now been captured digitally and are presented here along with images of the printed map sheet and component parts as PDF files. The Quaternary Geologic Map of the Jacksonville 4 degrees x 6 degrees Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the Earth. They make up the ground on which we walk, the dirt in which we dig foundations, and the soil in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale. In recent years, surficial deposits and materials have become the focus of much interest by scientists, environmentalists, governmental agencies, and the general public. They are the foundations of ecosystems, the materials that support plant growth and animal habitat, and the materials through which travels much of the water required for our agriculture, our industry, and our general well being. They also are materials that easily can become contaminated by pesticides, fertilizers, and toxic wastes. In this context, the value of the surficial geologic map is evident.

  13. Quaternary geologic map of the Florida Keys 4 degrees x 6 degrees quadrangle, United States

    USGS Publications Warehouse

    Compilations: Scott, Thomas M.; Knapp, Michael S.; Weide, David L.; Edited and integrated by Richmond, Gerald M.; Fullerton, David S.; Digital edition by Bush, Charles A.

    2010-01-01

    This map is part of the Quaternary Geologic Atlas of the United States (I-1420). It was first published as a printed edition in 1986. The geologic data have now been captured digitally and are presented here along with images of the printed map sheet and component parts as PDF files. The Quaternary Geologic Map of the Florida Keys 4 degrees x 6 degrees Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the Earth. They make up the ground on which we walk, the dirt in which we dig foundations, and the soil in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale. In recent years, surficial deposits and materials have become the focus of much interest by scientists, environmentalists, governmental agencies, and the general public. They are the foundations of ecosystems, the materials that support plant growth and animal habitat, and the materials through which travels much of the water required for our agriculture, our industry, and our general well being. They also are materials that easily can become contaminated by pesticides, fertilizers, and toxic wastes. In this context, the value of the surficial geologic map is evident.

  14. 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.

  15. Analysis by NASA's VESGEN Software of Retinal Blood Vessels in Human Subjects Undergoing Head-Down Tilt During 70-Day Bed Rest

    NASA Technical Reports Server (NTRS)

    Vyas, Ruchi J.; Murray, Matthew C.; Predovic, Marina; Lim, Shiyin; Askin, Kayleigh N.; Vizzeri, Gianmarco; Taibbi, Giovanni; Mason, Sara Stroble; Zanello, Susana B.; Young, Millenia; Parsons-Wingerter, Patricia

    2017-01-01

    Significant risks for visual impairment associated with increased intracranial pressure (VIIP) are incurred by microgravity spaceflight, especially long-duration missions [1]. We hypothesize that microgravity-induced fluid shifts result in pathological changes within blood vessels of the retina that precede development of visual and other ocular impairments. Potential contributions of retinal vascular remodeling to VIIP etiology are therefore being investigated for two studies in 30deg infrared (IR) Heidelberg Spectralis(Registered Trademark) images with NASA's innovative VESsel GENeration Analysis (VESGEN) software [2,3]. The retrospective studies include: (1) before, during and after (pre, mid and post) 6º head-down tilt (HDT) in human subjects during 70 days of bed rest, and (2) before and after missions to the International Space Station (ISS) by U.S. crew members. Results for both studies are almost complete. A preliminary example for HDT is described below.

  16. 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.

  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. 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

  19. 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.

  20. The Effects of Spaceflight and Head Down Tilt Bed Rest on Neurocognitive Performance: Extent, Longevity, and Neural Bases

    NASA Technical Reports Server (NTRS)

    Seidler, Rachael D.; Bloomberg, Jacob; Wood, Scott; Mulavara, Ajit; Kofman, Igor; De Dios, Yiri; Gadd, Nicole; Stepanyan, Vahagn

    2017-01-01

    Spaceflight effects on gait, balance, & manual motor control have been well studied; some evidence for cognitive deficits. Rodent cortical motor & sensory systems show neural structural alterations with spaceflight. specific Aims: Aim 1-Identify changes in brain structure, function, and network integrity as a function of head down tilt bed rest and spaceflight, and characterize their time course. Aim 2-Specify relationships between structural and functional brain changes and performance and characterize their time course.

  1. 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.

  2. NASA's Functional Task Test: Effects of Spaceflight and Six Degree Head-Down Bedrest on Dynamic Postural Stability

    NASA Technical Reports Server (NTRS)

    Taylor, L. C.; Batson, C. D.; Buxton, R. E.; Feiveson, A. H.; Kofman, I. S.; Laurie, S.; Lee, S. M. C.; Miller, C. A.; Mulavara, A. P.; Peters, B. T.; Phillips, T.; Platts, S. H.; Ploutz-Snyder, L. L.; Reschke, M. F.; Ryder, J. W.; Stenger, M. B.; Wood, S. J.; Bloomberg, J. J.

    2015-01-01

    The goals of the Functional Task Test (FTT) study were to determine the effects of spaceflight on functional tests that are representative of critical exploration mission tasks and to identify the physiological factors that contribute to decrements in performance.

  3. 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

  4. 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

  5. [Changes of serum alkaline phosphatase and electrolytes during 21 d head down bed-rest].

    PubMed

    Yao, Yong-jie; Sun, Xi-qing; Wang, Zhong-bo; Zhao, Shuang-bao; Yang, Chang-bin; Wu, Xing-yu

    2002-06-01

    Objective. To investigate the effect of simulated weightlessness on serum alkaline phosphatase (ALP), calcium, magnesium, chlorine and phosphorus. Method. 6 healthy males, aged 24.8 +/- 6.1, were exposed to -6 degrees HDT bed rest for 21 d. Activity of serum alkaline phosphatase, serum contents of calcium (Ca), magnesium (Mg), chlorine (Cl) and phosphorus (P) ions were assayed before HDT (d-3), on the 3rd, 10th and 21st day during HDT and after HDT (d+2). Ca was measured by methyl thymol blue method, P was determined with ultraviolet spectrophotography, determination of Mg and Cl were made with enzyme method, ALP was examined with 4-nitrobenzene phosphate method. Result. Serum Ca2+ levels were significantly higher at d10, d2l and d+2 than the value of d-3 (P<0.01). P3+ levels declined significantly on d2l as compared with d-3 (P<0.01). During the HDT and after HDT, Mg2+ declined to a level below that before HDT (P<0.05 or P<0.01). Cl- were significantly higher at d2l and d+2 than the value of d-3 (P<0.01). ALP level was higher on d2l than on d-3 (P<0.01). Conclusion. 21 d HDT induced increase of Ca, Cl, ALP, and decline of Mg and P. The changes may reflect the imbalance of metabolism.

  6. Head-down bed rest reduces the breathing rate short-term variability in subjects with orthostatic intolerance.

    PubMed

    Balocchi, R; Menicucci, D; Varanini, M; Chillemi, S; Legramante, J M; Saltini, C; Raimondi, G

    2004-07-01

    Orthostatic intolerance is the most serious symptom of cardiovascular deconditioning induced by microgravity. We have showed that in symptomatic subjects the baroreflex control of sinus node is affected by short term simulated microgravity. At present the influence of the respiration on the cardiovascular system in this condition is not clear. The aim of the present study was to examine the behaviour of the Breathing Rate (BR) in 5 Non-Symptomatic (NS) and 3 Symptomatic (S) subjects before and after 4 hours of head-down bed rest (HD).

  7. 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

  8. Effects of acute tilt from orthostatic to head-down antiorthostatic restraint and of sustained restraint on the intra-cerebroventricular pressure in rats.

    PubMed

    Maurel, D; Ixart, G; Barbanel, G; Mekaouche, M; Assenmacher, I

    1996-10-14

    The tail-cast suspension rat model was developed to explore in ground laboratories the physiological effects of some of the stresses prevailing during space flight including and among them those of the headwards body fluid shifts. We recently showed in rats that an acute head-down tilt (45 degrees) from tail-cast orthostatic (OR) to antiorthostatic restraint (AOR) induced within 30 min and for 2 to 4 h an acute stress-like surge in plasma ACTH and corticosterone levels. Considering the proximity of the CRF producing neurons with the 3rd ventricle, we decided to explore the acute and longer-term effects of the OR/AOR tilt on the intra-cerebroventricular pressure (Picv) measured with an indwelling sensor-transmitter catheter stereotaxically implanted in the 3rd ventricle. At 1- or 10-min intervals the unit sent radiotelemetric signals for both Picv and motor activity (MA) to a receiver coupled with an automatic data analyser. The acute AOR-tilt induced within 10 min and for 60 min a 2.5-fold rise in Picv which receded to baseline between 60 and 90 min. During this time, the normally close correlation between Picv and MA was lost, as assessed by Spearman's rank coefficient. In a long-term experimental series we explored the evolution of both Picv and MA in individual rats subjected successively to a 7 day control phase (C). 7 days OR, and 3 days AOR. After the 1-h-long post-tilt rise of the Picv, the mean Picv levels measured for the next 3 days decreased significantly vs. both the preceding OR phase (-30%) and the initial C Phase (-40%). The circadian pattern of the diurnal Picv profile was impaired, as evidenced by a significant fall (i) in the night/day ratio (-25% vs. C). and (ii) even more in the spectral power of the circadian 1 c/24 h frequency (-85% vs. C). The simultaneously recorded MA fluctuations similarly displayed an altered diurnal pattern with a spectral power of the circadian frequency reduced to 7% of controls. However, contrary to the short

  9. Quaternary geologic map of the Winnipeg 4 degrees x 6 degrees quadrangle, United States and Canada

    USGS Publications Warehouse

    Fullerton, D. S.; Ringrose, S.M.; Clayton, Lee; Schreiner, B.T.; Goebel, J.E.

    2000-01-01

    The Quaternary Geologic Map of the Winnipeg 4? ? 6? Quadrangle, United States and Canada, is a component of the U.S. Geological Survey Quaternary Geologic Atlas of the United States map series (Miscellaneous Investigations Series I-1420), an effort to produce 4? ? 6? Quaternary geologic maps, at 1:1 million scale, of the entire conterminous United States and adjacent Canada. The map and the accompanying text and supplemental illustrations provide a regional overview of the areal distributions and characteristics of surficial deposits and materials of Quaternary age (~1.8 Ma to present) in parts of North Dakota, Minnesota, Manitoba, and Saskatchewan. The map is not a map of soils as soils are recognized in agriculture. Rather, it is a map of soils as recognized in engineering geology, or of substrata or parent materials in which agricultural soils are formed. The map units are distinguished chiefly on the basis of (1)genesis (processes of origin) or environments of deposition: for example, sediments deposited primarily by glacial ice (glacial deposits or till), sediments deposited in lakes (lacustrine deposits), or sediments deposited by wind (eolian deposits); (2) age: for example, how long ago the deposits accumulated; (3) texture (grain size)of the deposits or materials; (4) composition (particle lithology) of the deposits or materials; (5) thickness; and (6) other physical, chemical, and engineering properties. Supplemental illustrations show (1) temporal correlation of the map units, (2) the areal relationships of late Wisconsin glacial ice lobes and sublobes, (3) temporal and spatial correlation of late Wisconsin glacial phases, readvance limits, and ice margin stillstands, (4) temporal and stratigraphic correlation of surface and subsurface glacial deposits in the Winnipeg quadrangle and in adjacent 4? ? 6? quadrangles, and (5) responsibility for state and province compilations. The database provides information related to geologic hazards (for example

  10. Quaternary geologic map of the Chesapeake Bay 4 degrees x 6 degrees quadrangle, United States

    USGS Publications Warehouse

    State compilations by Cleaves, Emery T.; Glaser, John D.; Howard, Alan D.; Johnson, Gerald H.; Wheeler, Walter H.; Sevon, William D.; Judson, Sheldon; Owens, James P.; Peebles, Pamela C.; edited and integrated by Richmond, Gerald Martin; Fullerton, David S.; Weide, David L.

    1987-01-01

    The Quaternary Geologic Map of the Chesapeake Bay 4? x 6? Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the Earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

  11. Quaternary geologic map of the Boston 4 degrees x 6 degrees quadrangle, United States and Canada

    USGS Publications Warehouse

    State compilations by Hartshorn, Joseph H.; Thompson, W.B.; Chapman, W.F.; Black, R.F.; Richmond, Gerald Martin; Grant, D.R.; Fullerton, David S.; edited and integrated by Richmond, Gerald Martin

    1991-01-01

    The Quaternary Geologic Map of the Boston 4 deg x 6 deg Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

  12. Quaternary geologic map of the Blue Ridge 4 degrees x 6 degrees quadrangle, United States

    USGS Publications Warehouse

    State compilations by Howard, Alan D.; Behling, Robert E.; Wheeler, Walter H.; Daniels, Raymond B.; Swadley, W.C.; Richmond, Gerald M.; Goldthwait, Richard P.; Sevon, William D.; Miller, Robert A.; Edited and integrated by Richmond, Gerald M.; Fullerton, David S.; Christiansen, Ann Coe; Digital edition by Bush, Charles A.

    1991-01-01

    This map is part of the Quaternary Geologic Atlas of the United States (I-1420). It was first published as a printed edition in 1986. The geologic data have now been captured digitally and are presented here along with images of the printed map sheet and component parts as PDF files. The Quaternary Geologic Map of the Blue Ridge 4° x 6° Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the "ground" on which we walk, the "dirt" in which we dig foundations, and the "soil" in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

  13. Quaternary geologic map of the Wichita 4 degrees x 6 degrees quadrangle, United States

    USGS Publications Warehouse

    State compilations by Denne, Jane E.; Luza, V.; Richmond, Gerald Martin; Jensen, Kathleen M.; Fishman, W.D.; Wermund, E.G.; Richmond, Gerald Martin; Christiansen, Ann Coe; Digital edition by Bush, Charles A.

    1993-01-01

    This map is part of the Quaternary Geologic Atlas of the United States (I-1420). It was first published as a printed edition in 1993. The geologic data have now been captured digitally and are presented here along with images of the printed map sheet and component parts as PDF files. The Quaternary Geologic Map of the Wichita 4° x 6° Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the "ground" on which we walk, the "dirt" in which we dig foundations, and the "soil" in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale. In recent years, surficial deposits and materials have become the focus of much interest by scientists, environmentalists, governmental agencies, and the general public. They are the foundations of ecosystems, the materials that support plant growth and animal habitat, and the materials through which travels much of the water required for our agriculture, our industry, and our general well being. They also are materials that easily can become contaminated by pesticides, fertilizers, and toxic wastes. In this context, the value of the surficial geologic map is evident.

  14. Heart rate and blood pressure response to short-term head-down bed rest: a nonlinear approach.

    PubMed

    Balocchi, R; Di Garbo, A; Michelassi, C; Chillemi, S; Varanini, M; Barbi, M; Legramante, J M; Raimondi, G; Zbilut, J P

    2000-06-01

    Although it is well-known that prolonged exposure to microgravity environment such as in space travel results in derangements of orthostasis, recent evidence suggests that even short-term exposure may have similar effects and parallels such common examples as prolonged bed rest. Whereas spectral analysis of heart rate and systolic blood pressure have been unable to detect changes, we hypothesized that nonlinear indexes may be better able to uncover such perturbations. Eighteen healthy subjects were exposed to 4-hour head-down tilt, and of these, 4 exhibited fainting. Two nonlinear indexes, mutual information and recurrence quantification were used to analyze the data. Only recurrence quantification was able to detect a "decoupling" of heart rate and systolic blood pressure at rest using discriminant analysis (p < 0.05). These results suggest that orthostatic intolerance may be due to a decoupling of heart rate from systolic blood pressure reflexive activity occurring at rest.

  15. 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).

  16. 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.

  17. Dynamic Cerebral Autoregulation is Preserved During Acute Head-down Tilt

    DTIC Science & Technology

    2003-06-27

    for statistical comparison. We used the slope method of Kautzner et al. (10) to assess cardiovagal baroreflex sensitivity during phase IV arterial... baroreflex sensitivity increased from 9.6 1.9 to 12.6 2.5 ms/mmHg, but this increase was not statistically significant (P 0.09). Figure 2 shows...power at the high fre- quency, and cardiovagal baroreflex sensitivity [as- sessed by the transfer function magnitude between systolic pressure and R-R

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

    PubMed

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

    2013-11-01

    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.

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. Clinical Evaluation of a Robotic 6-Degree of Freedom Treatment Couch for Frameless Radiosurgery

    SciTech Connect

    Gevaert, Thierry; Verellen, Dirk; Engels, Benedikt; Depuydt, Tom; Heuninckx, Karina; Tournel, Koen; Duchateau, Michael; Reynders, Truus; De Ridder, Mark

    2012-05-01

    Purpose: To evaluate the added value of 6-degree of freedom (DOF) patient positioning with a robotic couch compared with 4DOF positioning for intracranial lesions and to estimate the immobilization characteristics of the BrainLAB frameless mask (BrainLAB AG, Feldkirchen, Germany), more specifically, the setup errors and intrafraction motion. Methods and Materials: We enrolled 40 patients with 66 brain metastases treated with frameless stereotactic radiosurgery and a 6DOF robotic couch. Patient positioning was performed with the BrainLAB ExacTrac stereoscopic X-ray system. Positioning results were collected before and after treatment to assess patient setup error and intrafraction motion. Existing treatment planning data were loaded and simulated for 4DOF positioning and compared with the 6DOF positioning. The clinical relevance was analyzed by means of the Paddick conformity index and the ratio of prescribed isodose volume covered with 4DOF to that obtained with the 6DOF positioning. Results: The mean three-dimensional setup error before 6DOF correction was 1.91 mm (SD, 1.25 mm). The rotational errors were larger in the longitudinal (mean, 0.23 Degree-Sign ; SD, 0.82 Degree-Sign ) direction compared with the lateral (mean, -0.09 Degree-Sign ; SD, 0.72 Degree-Sign ) and vertical (mean, -0.10 Degree-Sign ; SD, 1.03 Degree-Sign ) directions (p < 0.05). The mean three-dimensional intrafraction shift was 0.58 mm (SD, 0.42 mm). The mean intrafractional rotational errors were comparable for the vertical, longitudinal, and lateral directions: 0.01 Degree-Sign (SD, 0.35 Degree-Sign ), 0.03 Degree-Sign (SD, 0.31 Degree-Sign ), and -0.03 Degree-Sign (SD, 0.33 Degree-Sign ), respectively. The mean conformity index decreased from 0.68 (SD, 0.08) (6DOF) to 0.59 (SD, 0.12) (4DOF) (p < 0.05). A loss of prescribed isodose coverage of 5% (SD, 0.08) was found with the 4DOF positioning (p < 0.05). Half a degree for longitudinal and lateral rotations can be identified as a threshold

  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. 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.

  9. Artificial gravity with ergometric exercise as a countermeasure against cardiovascular deconditioning during 4 days of head-down bed rest in humans.

    PubMed

    Wang, Yong-Chun; Yang, Chang-Bin; Wu, Yan-Hong; Gao, Yuan; Lu, Dong-Yuan; Shi, Fei; Wei, Xiao-Ming; Sun, Xi-Qing

    2011-09-01

    We have shown previously that combined short-arm centrifuge and aerobic exercise training preserved several physiologically important cardiovascular functions in humans. We hypothesized that artificial gravity (AG) and exercise is effective to prevent changes of physical problems during head-down bed rest (HDBR). To test this hypothesis, 12 healthy male subjects had undergone 4 days of 6° HDBR. Six of them were exposed to AG of an alternating 2-min intervals of +1.0 and +2.0 Gz at foot level for 30 min twice per day with ergometric exercise of 40 W as a countermeasure during bed rest (CM group), while the remaining six served as untreated controls (no-CM group). Before and after 4 days of bed rest, leg venous hemodynamics was assessed by venous occlusion plethysmography and autonomic cardiovascular control estimated by power spectral analysis of blood pressure and heart rate. Further, orthostatic tolerance was evaluated by a 75° head-up tilt test and physical working capacity was surveyed by near maximal physical working capacity test before and after bed rest. The data showed that combined centrifuge and exercise applied twice daily for a total of 60 min during 4 days of HDBR prevented (a) a decrease in working capacity, (b) autonomic dysfunction (a decrease in the activity of parasympathetic cardiac innervation) and (c) an increase in leg venous flow resistance. The combination of a 30 min alternating of +1.0 and +2.0 Gz for twice per day of AG with 40 W ergometric exercise may offer a promising countermeasure to short duration simulated microgravity.

  10. 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.

  11. 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

  12. 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

  13. Long Duration Head Down Tilt Bed Rest and Spaceflight 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.; Riascos-Castaneda, R. F.; Wood, S. J.; Bloomberg, J. J.

    2017-01-01

    We have recently completed a long duration head down tilt bed rest (HDBR) study in which we performed structural and functional magnetic resonance brain imaging to identify the relationships between changes in neurocognitive function and neural structural alterations in a spaceflight analog environment. We are also collecting the same measures in crewmembers prior to and following a six month International Space Station mission. We will present data demonstrating that bed rest resulted in functional mobility and balance deterioration with recovery post-HDBR. We observed numerous changes in brain structure, function, and connectivity relative to a control group which were associated with pre to post bed rest changes in sensorimotor function. For example, gray matter volume (GMv) increased in posterior parietal areas and decreased in frontal regions. GMv increases largely overlapped with fluid decreases and vice versa. Larger increases in precentral gyrus (M1)/ postcentral gyrus (S1+2) GMv and fluid decreases were associated with smaller balance decrements. Vestibular activation in the bilateral insular cortex increased with bed rest and subsequently recovered. Larger increases in vestibular activation in multiple brain regions were associated with greater decrements in balance and mobility. We found connectivity increases between left M1 with right S1+2 and the superior parietal lobule, and right vestibular cortex with the cerebellum. Decreases were observed between right Lobule VIII with right S1+2 and the supramarginal gyrus, right posterior parietal cortex (PPC) with occipital regions, and the right superior posterior fissure with right Crus I and II. Connectivity strength between left M1 and right S1+2/superior parietal lobule increased the most in individuals that exhibited the least balance impairments. In sum, we observed HDBR-related changes in measures of brain structure, function, and network connectivity, which correlated with indices of sensorimotor

  14. Disentangling cardiovascular control mechanisms during head-down tilt via joint transfer entropy and self-entropy decompositions

    PubMed Central

    Porta, Alberto; Faes, Luca; Marchi, Andrea; Bari, Vlasta; De Maria, Beatrice; Guzzetti, Stefano; Colombo, Riccardo; Raimondi, Ferdinando

    2015-01-01

    A full decomposition of the predictive entropy (PE) of the spontaneous variations of the heart period (HP) given systolic arterial pressure (SAP) and respiration (R) is proposed. The PE of HP is decomposed into the joint transfer entropy (JTE) from SAP and R to HP and self-entropy (SE) of HP. The SE is the sum of three terms quantifying the synergistic/redundant contributions of HP and SAP, when taken individually and jointly, to SE and one term conditioned on HP and SAP denoted as the conditional SE (CSE) of HP given SAP and R. The JTE from SAP and R to HP is the sum of two terms attributable to SAP or R plus an extra term describing the redundant/synergistic contribution to the JTE. All quantities were computed during cardiopulmonary loading induced by −25° head-down tilt (HDT) via a multivariate linear regression approach. We found that: (i) the PE of HP decreases during HDT; (ii) the decrease of PE is attributable to a lessening of SE of HP, while the JTE from SAP and R to HP remains constant; (iii) the SE of HP is dominant over the JTE from SAP and R to HP and the CSE of HP given SAP and R is prevailing over the SE of HP due to SAP and R both in supine position and during HDT; (iv) all terms of the decompositions of JTE from SAP and R to HP and SE of HP due to SAP and R were not affected by HDT; (v) the decrease of the SE of HP during HDT was attributed to the reduction of the CSE of HP given SAP and R; (vi) redundancy of SAP and R is prevailing over synergy in the information transferred into HP both in supine position and during HDT, while in the HP information storage synergy and redundancy are more balanced. The approach suggests that the larger complexity of the cardiac control during HDT is unrelated to the baroreflex control and cardiopulmonary reflexes and may be related to central commands and/or modifications of the dynamical properties of the sinus node. PMID:26578973

  15. Quaternary Geologic Map of the Lake Nipigon 4 Degrees x 6 Degrees Quadrangle, United States and Canada

    USGS Publications Warehouse

    Sado, Edward V.; Fullerton, David S.; Farrand, William R.; Edited and Integrated by Fullerton, David S.

    1994-01-01

    The Quaternary Geologic Map of the Lake Nipigon 4 degree x 6 degree Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale. This map is a product of collaboration of the Ontario Geological Survey, the University of Michigan, and the U.S. Geological Survey, and is designed for both scientific and practical purposes. It was prepared in two stages. First, separate maps and map explanations were prepared by the compilers. Second, the maps were combined, integrated, and supplemented by the editor. Map unit symbols were revised to a uniform system of classification and the map unit descriptions were prepared by the editor from information received from the compilers and from additional sources listed under Sources of Information. Diagrams accompanying the map were prepared by the editor. For scientific purposes, the map differentiates Quaternary surficial deposits on the basis of lithology or composition, texture or particle size, structure, genesis, stratigraphic relationships, engineering geologic properties, and relative age, as shown on the correlation diagram and indicated in the map unit descriptions. Deposits of some constructional landforms, such as kame moraine deposits, are distinguished as map units. Deposits of

  16. 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

  17. Super Strypi HWIL 6DOF (Hardware-In-Loop six-degree-of-freedom) Rev. 2175

    SciTech Connect

    Gilkey, Jeff C.; Harl, Nathan R.; Kowalchuk, Scott A.

    2016-02-23

    The Super Strypi HWIL is a six degree-of-freedom (6DOF) simulation for the Super Strypi Launch Vehicle. The simulation is used to test the NGC flight software including the navigation software. Aerodynamic and propulsive forces, mass properties, ACS (attitude control system) parameters are defined in input files. Output parameters are saved to a Matlab mat file.

  18. 16 CFR 254.6 - Deceptive use of diplomas, degrees, or certificates.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... GUIDES FOR PRIVATE VOCATIONAL AND DISTANCE EDUCATION SCHOOLS § 254.6 Deceptive use of diplomas, degrees... high school diploma unless the program of instruction to which it pertains is substantially equivalent to that offered by a resident secondary school, and unless the student is informed, by a clear...

  19. The design concept of the 6-degree-of-freedom hydraulic shaker at ESTEC

    NASA Technical Reports Server (NTRS)

    Brinkman, P. W.; Kretz, D.

    1992-01-01

    The European Space Agency (ESA) has decided to extend its test facilities at the European Space and Technology Center (ESTEC) at Noordwijk, The Netherlands, by implementing a 6-degree-of-freedom hydraulic shaker. This shaker will permit vibration testing of large payloads in the frequency range from 0.1 Hz to 100 Hz. Conventional single axis sine and random vibration modes can be applied without the need for a configuration change of the test set-up for vertical and lateral excitations. Transients occurring during launch and/or landing of space vehicles can be accurately simulated in 6-degrees-of-freedom. The performance requirements of the shaker are outlined and the results of the various trade-offs, which are investigated during the initial phase of the design and engineering program are provided. Finally, the resulting baseline concept and the anticipated implementation plan of the new test facility are presented.

  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. Super Strypi SWIL 6DOF (Software-In-Loop six-degree-of-freedom) Rev. 2175

    SciTech Connect

    Anderson, Mark A.; Bigelow, Matthew; Gilkey, Jeff C.; Harl, Nathan R.; Hutchinson, Lance V.; Kowalchuk, Scott A.; Madsen, Jared D.; Meindl, Mark A.; Outka, David E.; Schrempp, Mark T.

    2016-03-03

    The Super Strypi SWIL is a six degree-of-freedom (6DOF) simulation for the Super Strypi Launch Vehicle that includes a subset of the Super Strypi NGC software (guidance, ACS and sequencer). Aerodynamic and propulsive forces, mass properties, ACS (attitude control system) parameters, guidance parameters and Monte-Carlo parameters are defined in input files. Output parameters are saved to a Matlab mat file.

  2. 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

  3. PCSK6 VNTR Polymorphism Is Associated with Degree of Handedness but Not Direction of Handedness.

    PubMed

    Arning, Larissa; Ocklenburg, Sebastian; Schulz, Stefanie; Ness, Vanessa; Gerding, Wanda M; Hengstler, Jan G; Falkenstein, Michael; Epplen, Jörg T; Güntürkün, Onur; Beste, Christian

    2013-01-01

    Although the left and right human cerebral hemispheres differ both functionally and anatomically, the mechanisms that underlie the establishment of these hemispheric specializations, as well as their physiological and behavioral implications, remain largely unknown. Since cerebral asymmetry is strongly correlated with handedness, and handedness is assumed to be influenced by a number of genetic and environmental factors, we performed an association study of LRRTM1 rs6733871 and a number of polymorphisms in PCSK6 and different aspects of handedness assessed with the Edinburgh handedness inventory in a sample of unrelated healthy adults (n = 1113). An intronic 33bp variable-number tandem repeat (VNTR) polymorphism in PCSK6 (rs10523972) shows a significant association (significance threshold: p<0.0025, adjusted for multiple comparisons) with a handedness category comparison (P = 0.0005) and degree of handedness (P = 0.001). These results provide further evidence for the role of PCSK6 as candidate for involvement in the biological mechanisms that underlie the establishment of normal brain lateralization and thus handedness and support the assumption that the degree of handedness, instead the direction, may be the more appropriate indicator of cerebral organization.

  4. Quaternary geologic map of the Lake Erie 4 degrees x 6 degrees quadrangle, United States and Canada

    USGS Publications Warehouse

    Fullerton, David S.; Richmond, Gerald M.; state compilations by Fullerton, David S.; Cowan, W.R.; Sevon, W.D.; Goldthwait, R.P.; Farrand, W.R.; Muller, E.H.; Behling, R.E.; Stravers, J.A.; edited and integrated by Fullerton, David S.; Richmond, Gerald Martin

    1991-01-01

    The Quaternary Geologic Map of the Lake Erie 4? x 6? Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

  5. Quaternary geologic map of the Hudson River 4 degree x 6 degree quadrangle, United States and Canada

    USGS Publications Warehouse

    State and province compilations by Fullerton, David S.; Sevon, William D.; Muller, Ernest H.; Judson, Sheldon; Black, Robert F.; Wagner, Phillip W.; Hartshorn, Joseph H.; Chapman, William F.; Cowan, William D.; edited and integrated by Fullerton, David S.

    1992-01-01

    The Quaternary Geologic Map of the Hudson River 4? x 6? Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

  6. Quaternary Geologic Map of the Lake of the Woods 4 Degrees x 6 Degrees Quadrangle, United States and Canada

    USGS Publications Warehouse

    Sado, Edward V.; Fullerton, David S.; Goebel, Joseph E.; Ringrose, Susan M.; Edited and Integrated by Fullerton, David S.

    1995-01-01

    The Quaternary Geologic Map of the Lake of the Woods 4 deg x 6 deg Quadrangle, United States and Canada, was mapped as part of the U.S. Geological Survey Quaternary Geologic Atlas of the United States map series (Miscellaneous Investigations Series I-1420, NM-15). The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale. This map is a product of collaboration of the Ontario Geological Survey, the Minnesota Geological Survey, the Manitoba Department of Energy and Mines, and the U.S. Geological Survey, and is designed for both scientific and practical purposes. It was prepared in two stages. First, separate maps and map explanations were prepared by the compilers. Second, the maps were combined, integrated, and supplemented by the editor. Map unit symbols were revised to a uniform system of classification and the map unit descriptions were prepared by the editor from information received from the compilers and from additional sources listed under Sources of Information. Diagrams accompanying the map were prepared by the editor. For scientific purposes, the map differentiates Quaternary surficial deposits on the basis of lithology or composition, texture or particle size, structure, genesis, stratigraphic relationships, engineering geologic properties, and relative age, as shown on the correlation diagram and

  7. 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.

  8. Check-Cases for Verification of 6-Degree-of-Freedom Flight Vehicle Simulations

    NASA Technical Reports Server (NTRS)

    Murri, Daniel G.; Jackson, E. Bruce; Shelton, Robert O.

    2015-01-01

    The rise of innovative unmanned aeronautical systems and the emergence of commercial space activities have resulted in a number of relatively new aerospace organizations that are designing innovative systems and solutions. These organizations use a variety of commercial off-the-shelf and in-house-developed simulation and analysis tools including 6-degree-of-freedom (6-DOF) flight simulation tools. The increased affordability of computing capability has made highfidelity flight simulation practical for all participants. Verification of the tools' equations-of-motion and environment models (e.g., atmosphere, gravitation, and geodesy) is desirable to assure accuracy of results. However, aside from simple textbook examples, minimal verification data exists in open literature for 6-DOF flight simulation problems. This assessment compared multiple solution trajectories to a set of verification check-cases that covered atmospheric and exo-atmospheric (i.e., orbital) flight. Each scenario consisted of predefined flight vehicles, initial conditions, and maneuvers. These scenarios were implemented and executed in a variety of analytical and real-time simulation tools. This tool-set included simulation tools in a variety of programming languages based on modified flat-Earth, round- Earth, and rotating oblate spheroidal Earth geodesy and gravitation models, and independently derived equations-of-motion and propagation techniques. The resulting simulated parameter trajectories were compared by over-plotting and difference-plotting to yield a family of solutions. In total, seven simulation tools were exercised.

  9. Determining patient 6-degrees-of-freedom motion from stereo infrared cameras during supine medical imaging

    NASA Astrophysics Data System (ADS)

    Beach, Richard D.; Feng, Bing; Shazeeb, Mohammed S.; King, Michael A.

    2006-03-01

    Patient motion during SPECT acquisition causes inconsistent projection data and reconstruction artifacts which can significantly affect the diagnostic accuracy of SPECT. The tracking of motion by infrared monitoring spherical reflectors (markers) on the patient's surface can provide 6-Degrees-of-Freedom (6-DOF) motion information capable of providing clinically robust correction. Object rigid-body motion can be described by 3 translational DOF and 3 rotational DOF. Polaris marker position information obtained by stereo infrared cameras requires algorithmic processing to correctly record the tracked markers, and to calibrate and map Polaris co-ordinate data into the SPECT co-ordinate system. Marker data then requires processing to determine the rotational and translational 6-DOF motion to ultimately be used for SPECT image corrections. This processing utilizes an algorithm involving least-squares fitting, to each other, of two 3-D point sets using singular value decomposition (SVD) resulting in the rotation matrix and translation of the rigid body centroid. We have demonstrated the ability to monitor 12 clinical patients as well as 7 markers on 2 elastic belts worn by a volunteer while intentionally moving, and determined the 3 axis Euclidian rotation angles and centroid translations. An anthropomorphic phantom with Tc-99m added to the heart, liver, and body was simultaneously SPECT imaged and motion tracked using 4 rigidly mounted markers. The determined rotation matrix and translation information was used to correct the image resulting in virtually identical "no motion" and "corrected" images. We plan to initiate routine 6-DOF tracking of patient motion during SPECT imaging in the future.

  10. Master's Degrees in the State University System of Florida. Information Brief. Volume 6, Issue 1

    ERIC Educational Resources Information Center

    Florida Board of Governors, State University System, 2008

    2008-01-01

    A master's degree is a postbaccalaureate academic degree awarded after one to three years of full-time academic study. The State University System (SUS) of Florida offers master's degree programs in a variety of disciplines and at all universities, with the exception of New College. Students travel to Florida from throughout the world to earn…

  11. Development and calibration of an accurate 6-degree-of-freedom measurement system with total station

    NASA Astrophysics Data System (ADS)

    Gao, Yang; Lin, Jiarui; Yang, Linghui; Zhu, Jigui

    2016-12-01

    To meet the demand of high-accuracy, long-range and portable use in large-scale metrology for pose measurement, this paper develops a 6-degree-of-freedom (6-DOF) measurement system based on total station by utilizing its advantages of long range and relative high accuracy. The cooperative target sensor, which is mainly composed of a pinhole prism, an industrial lens, a camera and a biaxial inclinometer, is designed to be portable in use. Subsequently, a precise mathematical model is proposed from the input variables observed by total station, imaging system and inclinometer to the output six pose variables. The model must be calibrated in two levels: the intrinsic parameters of imaging system, and the rotation matrix between coordinate systems of the camera and the inclinometer. Then corresponding approaches are presented. For the first level, we introduce a precise two-axis rotary table as a calibration reference. And for the second level, we propose a calibration method by varying the pose of a rigid body with the target sensor and a reference prism on it. Finally, through simulations and various experiments, the feasibilities of the measurement model and calibration methods are validated, and the measurement accuracy of the system is evaluated.

  12. Monocular-Based 6-Degree of Freedom Pose Estimation Technology for Robotic Intelligent Grasping Systems.

    PubMed

    Liu, Tao; Guo, Yin; Yang, Shourui; Yin, Shibin; Zhu, Jigui

    2017-02-14

    Industrial robots are expected to undertake ever more advanced tasks in the modern manufacturing industry, such as intelligent grasping, in which robots should be capable of recognizing the position and orientation of a part before grasping it. In this paper, a monocular-based 6-degree of freedom (DOF) pose estimation technology to enable robots to grasp large-size parts at informal poses is proposed. A camera was mounted on the robot end-flange and oriented to measure several featured points on the part before the robot moved to grasp it. In order to estimate the part pose, a nonlinear optimization model based on the camera object space collinearity error in different poses is established, and the initial iteration value is estimated with the differential transformation. Measuring poses of the camera are optimized based on uncertainty analysis. Also, the principle of the robotic intelligent grasping system was developed, with which the robot could adjust its pose to grasp the part. In experimental tests, the part poses estimated with the method described in this paper were compared with those produced by a laser tracker, and results show the RMS angle and position error are about 0.0228° and 0.4603 mm. Robotic intelligent grasping tests were also successfully performed in the experiments.

  13. Monocular-Based 6-Degree of Freedom Pose Estimation Technology for Robotic Intelligent Grasping Systems

    PubMed Central

    Liu, Tao; Guo, Yin; Yang, Shourui; Yin, Shibin; Zhu, Jigui

    2017-01-01

    Industrial robots are expected to undertake ever more advanced tasks in the modern manufacturing industry, such as intelligent grasping, in which robots should be capable of recognizing the position and orientation of a part before grasping it. In this paper, a monocular-based 6-degree of freedom (DOF) pose estimation technology to enable robots to grasp large-size parts at informal poses is proposed. A camera was mounted on the robot end-flange and oriented to measure several featured points on the part before the robot moved to grasp it. In order to estimate the part pose, a nonlinear optimization model based on the camera object space collinearity error in different poses is established, and the initial iteration value is estimated with the differential transformation. Measuring poses of the camera are optimized based on uncertainty analysis. Also, the principle of the robotic intelligent grasping system was developed, with which the robot could adjust its pose to grasp the part. In experimental tests, the part poses estimated with the method described in this paper were compared with those produced by a laser tracker, and results show the RMS angle and position error are about 0.0228° and 0.4603 mm. Robotic intelligent grasping tests were also successfully performed in the experiments. PMID:28216555

  14. Computing Dynamics Of A Robot Of 6+n Degrees Of Freedom

    NASA Technical Reports Server (NTRS)

    Quiocho, Leslie J.; Bailey, Robert W.

    1995-01-01

    Improved formulation speeds and simplifies computation of dynamics of robot arm of n rotational degrees of freedom mounted on platform having three translational and three rotational degrees of freedom. Intended for use in dynamical modeling of robotic manipulators attached to such moving bases as spacecraft, aircraft, vessel, or land vehicle. Such modeling important part of simulation and control of robotic motions.

  15. First discoveries of z ˜ 6 quasars with the Kilo-Degree Survey and VISTA Kilo-Degree Infrared Galaxy survey

    NASA Astrophysics Data System (ADS)

    Venemans, B. P.; Verdoes Kleijn, G. A.; Mwebaze, J.; Valentijn, E. A.; Bañados, E.; Decarli, R.; de Jong, J. T. A.; Findlay, J. R.; Kuijken, K. H.; Barbera, F. La; McFarland, J. P.; McMahon, R. G.; Napolitano, N.; Sikkema, G.; Sutherland, W. J.

    2015-11-01

    We present the results of our first year of quasar search in the ongoing ESO public Kilo-Degree Survey (KiDS) and VISTA Kilo-Degree Infrared Galaxy (VIKING) surveys. These surveys are among the deeper wide-field surveys that can be used to uncover large numbers of z ˜ 6 quasars. This allows us to probe a more common population of z ˜ 6 quasars that is fainter than the well-studied quasars from the main Sloan Digital Sky Survey. From this first set of combined survey catalogues covering ˜250 deg2 we selected point sources down to ZAB = 22 that had a very red i - Z (i - Z > 2.2) colour. After follow-up imaging and spectroscopy, we discovered four new quasars in the redshift range 5.8 < z < 6.0. The absolute magnitudes at a rest-frame wavelength of 1450 Å are between -26.6 < M1450 < -24.4, confirming that we can find quasars fainter than M*, which at z = 6 has been estimated to be between M* = -25.1 and M* = -27.6. The discovery of four quasars in 250 deg2 of survey data is consistent with predictions based on the z ˜ 6 quasar luminosity function. We discuss various ways to push the candidate selection to fainter magnitudes and we expect to find about 30 new quasars down to an absolute magnitude of M1450 = -24. Studying this homogeneously selected faint quasar population will be important to gain insight into the onset of the co-evolution of the black holes and their stellar hosts.

  16. 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.

  17. Color Head Down Display Program

    DTIC Science & Technology

    1993-04-01

    energy is converted 36 to the mission of UV light at a wavelength of 2537 A. Thw inner surface of the lamp is coned with phosphns selected to transform... rradiation of silicon with neunrns is known to beta of bipolar transistors and, therefore, increase the breakdown of the SOI floating substrate MOS...was also an incmse in leakage current after rradiation , but we were able to reduce it by doing a Postirradiation anneal 52 14- , 1 3 -e-- GILm Vbdn - 12

  18. 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

  19. The effects of head-up and head-down tilt on central respiratory chemoreflex loop gain tested by hyperoxic rebreathing.

    PubMed

    Skow, Rachel J; Tymko, Michael M; MacKay, Christina M; Steinback, Craig D; Day, Trevor A

    2014-01-01

    Central respiratory chemosensitivity is mediated via chemoreceptor neurons located throughout brain stem tissue. These receptors detect proximal CO2/[H(+)] (i.e., controller gain) and modulate breathing in a classic negative feedback loop. Loop gain (responsiveness) is the theoretical product of controller (chemoreceptors), mixing/feedback (cardiovascular and cerebrovascular systems), and plant (pulmonary system) gains. The level of chemoreceptor stimulation is determined by interactions between mixing and plant gains. The extent to which steady-state changes in body position may affect central chemoreflex loop gain in response to CO2 is unclear. Because of the potential effects of tilt on pulmonary mechanics, we hypothesized that plant gain would be altered by head-up and head-down tilt (HUT, HDT) during hyperoxic rebreathing, which theoretically isolates plant gain by eliminating systemic arterial-tissue gradients. Sixteen subjects (eight females) underwent hyperoxic rebreathing tests on a tilt table to quantify central chemoreflex loop gain in five steady-state positions: 90° HUT, 45° HUT, supine, 45° HDT, and 90° HDT. Respiratory responses (tidal volume, VT; frequency, fR; minute ventilation, VE) were quantified during steady-state and increases in CO2 during rebreathing by linear regression above the ventilatory recruitment threshold (VRT). Using one-factor analysis of variance, we found that there were no differences in the respiratory responses between the five positions (VRT, P=0.711; VT, P=0.290; fR, P=0.748; VE, P=0.325). Our findings suggest that during steady-state orthostatic stress, the ability of subjects to mount a normal ventilatory response to increased CO2 was unaffected, despite any potential changes in pulmonary mechanics associated with positional challenges.

  20. Rattlesnake Mountain Observator (46.4{degrees}N, 119.6{degrees}W) multispectral optical depth measurements, 1979--1994

    SciTech Connect

    Daniels, R.C.

    1995-09-22

    Surface measurements of solar irradiance of the atmosphere were made by a multipurpose computer-controlled scanning photometer at the Rattlesnake Mountain Observatory. The observatory is located at 46.4{degrees}N, 119.6{degrees}W at an elevation of 1088 m above mean sea level. The photometer measures the attenuation of direct solar radiation for different wavelengths using 12 filters. Five of these filters (ie., at 428 nm, 486 nm, 535 nm, 785 nm, and 1010 nm, with respective half-power widths of 2, 2, 3, 18, and 28 nm) are suitable for monitoring variations in the total optical depth of the atmosphere. Total optical depths for the five wavelength bands were derived from solar irradiance measurements taken at the observatory from August 5, 1979, to September 2, 1994; these total optical depth data are distributed with this numeric data package (NDP). To determine the contribution of atmospheric aerosols to the total optical depths, the effects of Rayleigh scattering and ozone absorption were subtracted (other molecular scattering was minimal for the five filters) to obtain total column aerosol optical depths. The total aerosol optical depths were further decomposed into tropospheric and stratospheric components by calculating a robustly smoothed mean background optical depth (tropospheric component) for each wavelength using data obtained during periods of low stratospheric aerosol loading. By subtracting the smoothed background tropospheric aerosol optical depths from the total aerosol optical depths, residual aerosol optical depths were obtained. These residuals are good estimates of the stratospheric aerosol optical depth at each wavelength and may be used to monitor the long-term effects of volcanic eruptions on the atmosphere. These data are available as an NDP from the Carbon Dioxide Information Analysis Center (CDIAC), and the NDP consists of this document and a set of computerized data files.

  1. PHF6 Degrees of Separation: The Multifaceted Roles of a Chromatin Adaptor Protein

    PubMed Central

    Todd, Matthew A.M.; Ivanochko, Danton; Picketts, David J.

    2015-01-01

    The importance of chromatin regulation to human disease is highlighted by the growing number of mutations identified in genes encoding chromatin remodeling proteins. While such mutations were first identified in severe developmental disorders, or in specific cancers, several genes have been implicated in both, including the plant homeodomain finger protein 6 (PHF6) gene. Indeed, germline mutations in PHF6 are the cause of the Börjeson–Forssman–Lehmann X-linked intellectual disability syndrome (BFLS), while somatic PHF6 mutations have been identified in T-cell acute lymphoblastic leukemia (T-ALL) and acute myeloid leukemia (AML). Studies from different groups over the last few years have made a significant impact towards a functional understanding of PHF6 protein function. In this review, we summarize the current knowledge of PHF6 with particular emphasis on how it interfaces with a distinct set of interacting partners and its functional roles in the nucleoplasm and nucleolus. Overall, PHF6 is emerging as a key chromatin adaptor protein critical to the regulation of neurogenesis and hematopoiesis. PMID:26103525

  2. Effects on respiratory function of the head-down position and the complete covering of the face by drapes during insertion of the monitoring catheters in the cardiosurgical patient

    PubMed Central

    Bertolissi, Massimo; Bassi, Flavio; Silvestre, Adriana Di; Giordano, Francesco

    1999-01-01

    Background: We evaluated the effect on the respiratory gas exchange of the 30° head-down position and the complete covering of the face by sterile drapes. These are used to cannulate the internal jugular vein and position the pulmonary artery catheter in the cardiosurgical patient. During the two manoeuvres, 20 coronary patients and 10 patients with end-stage heart disease were supplied with oxygen (FiO2 =0.4) by a Venturi mask, while 20 coronary patients breathed room air. The arterial blood samples to measure oxygen (PaO2) and carbon dioxide (PaCO2) tension and oxygen saturation (SaO2) were analysed by a blood gas system. Results: The contemporary application of the head-down position and the drapes over the face significantly increased PaO2 and SaO2 in all the patientssupplied with oxygen. Without the head-down position, leaving the drapes over the face, did not significantly change the two parameters in the coronary patients supplied with oxygen, but induced a significant increase in PaO2 and SaO2 in the patients with end-stage heart disease. In the coronary patients that were breathing room air, PaO2 and SaO2 were stable throughout the study. Conclusions: We conclude that the 30° head-down position and the complete covering of the face by drapes does not interfere with respiratory gas exchange and can be safely performed in coronary patients supplied with oxygen or breathing room air and in patients with end-stage heart disease supplied with oxygen (FiO2 of 0.4). PMID:11056729

  3. Proper central and core polynomials of relatively free associative algebras with identity of Lie nilpotency of degrees 5 and 6

    NASA Astrophysics Data System (ADS)

    Grishin, A. V.; Pchelintsev, S. V.

    2016-12-01

    We study the centre of a relatively free associative algebra F(n) with the identity [x_1,\\dots,x_n]=0 of Lie nilpotency of degree n= 5,6 over a field of characteristic 0. It is proved that the core Z^*(F(5)) of the algebra F(5) (the sum of all ideals of F(5) contained in its centre) is generated as a T-ideal by the weak Hall polynomial [[x,y]2,y]. It is also proved that every proper central polynomial of F(5) is contained in the sum of Z^*(F(5)) and the T-space generated by [[x,y]2, z] and the commutator [x_1,\\dots, x_4] of degree 4. This implies that the centre of F(5) is contained in the T-ideal generated by the commutator of degree 4. Similar results are obtained for F(6); in particular, it is proved that the core Z*(F(6)) is generated as a T-ideal by the commutator of degree 5. Bibliography: 15 titles.

  4. Implementation issues for a compact 6 degree of freedom force reflecting handcontroller with cueing of modes

    NASA Technical Reports Server (NTRS)

    Jacobus, Heidi; Riggs, Alan J.; Jacobus, Charles; Weinstein, Yechiel

    1991-01-01

    Teleoperated control requires a master human interface device that can provide haptic input and output which reflect the responses of a slave robotic system. The effort reported in this paper addresses the design and prototyping of a six degree-of-freedom (DOF) Cartesian coordinate hand controller for this purpose. The device design recommended is an XYZ stage attached to a three-roll wrist which positions a flight-type handgrip. Six degrees of freedom are transduced and control brushless DC motor servo electronics similar in design to those used in computer controlled robotic manipulators. This general approach supports scaled force, velocity, and position feedback to aid an operator in achieving telepresence. The generality of the device and control system characteristics allow the use of inverse dynamics robotic control methodology to project slave robot system forces and inertias to the operator (in scaled form) and at the same time to reduce the apparent inertia of the robotic handcontroller itself. The current control design, which is not multiple fault tolerant, can be extended to make flight control or space use possible. The proposed handcontroller will have advantages in space-based applications where an operator must control several robot arms in a simultaneous and coordinated fashion. It will also have applications in intravehicular activities (within the Space Station) such as microgravity experiments in metallurgy and biological experiments that require isolation from the astronauts' environment. For ground applications, the handcontroller will be useful in underwater activities where the generality of the proposed handcontroller becomes an asset for operation of many different manipulator types. Also applications will emerge in the Military, Construction, and Maintenance/Manufacturing areas including ordnance handling, mine removal, NBC (Nuclear, Chemical, Biological) operations, control of vehicles, and operating strength and agility enhanced

  5. Experimental validation of a newly designed 6 degrees of freedom scanning laser head: application to three-dimensional beam structure.

    PubMed

    Di Maio, D; Copertaro, E

    2013-12-01

    A new scanning laser head is designed to use single Laser Doppler Vibrometer (LDV) for performing measurements up to 6 degrees of freedom (DOF) at a target. The scanning head is supported by a rotating hollow shaft, which allows the laser beam to travel up to the scanning head from an opposite direction where an LDV is set up. The scanning head is made of a set of two mirrors, which deflects the laser beam with an angle so that the rotation of the scanning head produces a conical scan. When measurements are performed at the focal point of the conical scan then three translational vibration components can be measured, otherwise the very small circle scan, before and after the focal point, can measure up to 6 degrees of freedom, including three translations and three rotations. This paper presents the 6DOF scanning head and the measurements of 3D operational deflection shapes of a test structure.

  6. Experimental validation of a newly designed 6 degrees of freedom scanning laser head: Application to three-dimensional beam structure

    NASA Astrophysics Data System (ADS)

    Di Maio, D.; Copertaro, E.

    2013-12-01

    A new scanning laser head is designed to use single Laser Doppler Vibrometer (LDV) for performing measurements up to 6 degrees of freedom (DOF) at a target. The scanning head is supported by a rotating hollow shaft, which allows the laser beam to travel up to the scanning head from an opposite direction where an LDV is set up. The scanning head is made of a set of two mirrors, which deflects the laser beam with an angle so that the rotation of the scanning head produces a conical scan. When measurements are performed at the focal point of the conical scan then three translational vibration components can be measured, otherwise the very small circle scan, before and after the focal point, can measure up to 6 degrees of freedom, including three translations and three rotations. This paper presents the 6DOF scanning head and the measurements of 3D operational deflection shapes of a test structure.

  7. Experimental validation of a newly designed 6 degrees of freedom scanning laser head: Application to three-dimensional beam structure

    SciTech Connect

    Di Maio, D.; Copertaro, E.

    2013-12-15

    A new scanning laser head is designed to use single Laser Doppler Vibrometer (LDV) for performing measurements up to 6 degrees of freedom (DOF) at a target. The scanning head is supported by a rotating hollow shaft, which allows the laser beam to travel up to the scanning head from an opposite direction where an LDV is set up. The scanning head is made of a set of two mirrors, which deflects the laser beam with an angle so that the rotation of the scanning head produces a conical scan. When measurements are performed at the focal point of the conical scan then three translational vibration components can be measured, otherwise the very small circle scan, before and after the focal point, can measure up to 6 degrees of freedom, including three translations and three rotations. This paper presents the 6DOF scanning head and the measurements of 3D operational deflection shapes of a test structure.

  8. Experimental Study of Second-Mode Instabilities on a 7-Degree Cone at Mach 6

    NASA Technical Reports Server (NTRS)

    Rufer, Shann J.; Berridge, Dennis C.

    2011-01-01

    Experiments have been carried out in the NASA Langley Research Center 20-Inch Mach 6 Air Tunnel to measure the second-mode boundary-layer instability on a 7deg half-angle cone using high-frequency pressure sensors. Data were obtained with both blunt and sharp nosetips installed on the cone. The second-mode wave amplitudes were observed to saturate and then begin to decrease in the Langley tunnels, indicating wave breakdown. Pressure fluctuation measurements and thermocouple data indicated the location of transition along the cone at the different conditions tested. Comparisons between the power density spectra obtained during the current test and previous data from the Langley 15-Inch Mach 6 High Temperature Tunnel and the Boeing/AFOSR Mach 6 Quiet tunnel illustrate the effect of tunnel noise on instability growth and transition.

  9. MLTE: An LTE Solver for Diatomic Molecules and Atoms above 6,000 Degrees K

    DTIC Science & Technology

    2007-11-02

    Bresmann, " SOLGASMIX - PV , A Computer Program to Calculate Equilibrium Relationships in Complex Chemical Systems", Oak Ridge National Laboratory Report...34 equilibria solvers for use on mainframe computers have emerged, among them are SOLGASMIX [Ref.l] and CHEMKIN [Ref.6]. To evaluate the free energy of a

  10. 16 CFR 254.6 - Deceptive use of diplomas, degrees, or certificates.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... high school diploma unless the program of instruction to which it pertains is substantially equivalent to that offered by a resident secondary school, and unless the student is informed, by a clear and... GUIDES FOR PRIVATE VOCATIONAL AND DISTANCE EDUCATION SCHOOLS § 254.6 Deceptive use of diplomas,...

  11. 16 CFR 254.6 - Deceptive use of diplomas, degrees, or certificates.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... high school diploma unless the program of instruction to which it pertains is substantially equivalent to that offered by a resident secondary school, and unless the student is informed, by a clear and... GUIDES FOR PRIVATE VOCATIONAL AND DISTANCE EDUCATION SCHOOLS § 254.6 Deceptive use of diplomas,...

  12. 16 CFR 254.6 - Deceptive use of diplomas, degrees, or certificates.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    .... (c) It is deceptive for an Industry Member to offer or confer a high school diploma unless the... secondary school, and unless the student is informed, by a clear and conspicuous disclosure in writing prior... GUIDES FOR PRIVATE VOCATIONAL AND DISTANCE EDUCATION SCHOOLS § 254.6 Deceptive use of diplomas,...

  13. 16 CFR 254.6 - Deceptive use of diplomas, degrees, or certificates.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... high school diploma unless the program of instruction to which it pertains is substantially equivalent to that offered by a resident secondary school, and unless the student is informed, by a clear and... GUIDES FOR PRIVATE VOCATIONAL AND DISTANCE EDUCATION SCHOOLS § 254.6 Deceptive use of diplomas,...

  14. Six-degree-of-freedom program to optimize simulated trajectories (6D POST). Volume 1: Formulation manual

    NASA Technical Reports Server (NTRS)

    Brauer, G. L.; Habeger, A. R.; Stevenson, R.

    1974-01-01

    The basic equations and models used in a computer program (6D POST) to optimize simulated trajectories with six degrees of freedom were documented. The 6D POST program was conceived as a direct extension of the program POST, which dealt with point masses, and considers the general motion of a rigid body with six degrees of freedom. It may be used to solve a wide variety of atmospheric flight mechanics and orbital transfer problems for powered or unpowered vehicles operating near a rotating oblate planet. Its principal features are: an easy to use NAMELIST type input procedure, an integrated set of Flight Control System (FCS) modules, and a general-purpose discrete parameter targeting and optimization capability. It was written in FORTRAN 4 for the CDC 6000 series computers.

  15. The pair and major merger history of galaxies up to z=6 over 3 square degrees

    NASA Astrophysics Data System (ADS)

    Conselice, Christopher; Mundy, Carl; Duncan, Kenneth

    2017-01-01

    A major goal in extragalactic astronomy is understanding how stars and gas are put into galaxies. As such we present the pair fraction and derived major merger and stellar mass assembly histories of galaxies up to z = 6. We do this using new techniques from photometric redshift probability distribution functions, and state of the art deep near-infrared data from the UDS, VIDEO and UltraVISTA COSMOS fields for galaxies at z < 3, and CANDELS data for galaxies at 3 < z < 6. We find that major mergers at high redshift are not the dominant mode of placing stars into galaxies, but that star formation is a more important process by factors of 10 or higher. At z < 3 major mergers will at most double the masses of galaxies, depending on the stellar mass or number density selection method. At z < 1 we find that major mergers deposit more stellar mass into galaxies than star formation, the reverse of the process seen at higher redshifts. However, at z > 1 there must be a very important unknown mode of baryonic acquisition within galaxies that is not associated with major mergers. We further discuss how the merger history stays relatively constant at higher redshifts, and show the comparison of our results to theoretical predictions.

  16. Discovery of three z > 6.5 quasars in the VISTA kilo-degree infrared galaxy (VIKING) survey

    SciTech Connect

    Venemans, B. P.; Findlay, J. R.; Sutherland, W. J.; De Rosa, G.; McMahon, R. G.; González-Solares, E. A.; Lewis, J. R.; Simcoe, R.; Kuijken, K.

    2013-12-10

    Studying quasars at the highest redshifts can constrain models of galaxy and black hole formation, and it also probes the intergalactic medium in the early universe. Optical surveys have to date discovered more than 60 quasars up to z ≅ 6.4, a limit set by the use of the z-band and CCD detectors. Only one z ≳ 6.4 quasar has been discovered, namely the z = 7.08 quasar ULAS J1120+0641, using near-infrared imaging. Here we report the discovery of three new z ≳ 6.4 quasars in 332 deg{sup 2} of the Visible and Infrared Survey Telescope for Astronomy Kilo-degree Infrared Galaxy (VIKING) survey, thus extending the number from 1 to 4. The newly discovered quasars have redshifts of z = 6.60, 6.75, and 6.89. The absolute magnitudes are between –26.0 and –25.5, 0.6-1.1 mag fainter than ULAS J1120+0641. Near-infrared spectroscopy revealed the Mg II emission line in all three objects. The quasars are powered by black holes with masses of ∼(1-2) × 10{sup 9} M {sub ☉}. In our probed redshift range of 6.44 < z < 7.44 we can set a lower limit on the space density of supermassive black holes of ρ(M {sub BH} > 10{sup 9} M {sub ☉}) > 1.1 × 10{sup –9} Mpc{sup –3}. The discovery of three quasars in our survey area is consistent with the z = 6 quasar luminosity function when extrapolated to z ∼ 7. We do not find evidence for a steeper decline in the space density of quasars with increasing redshift from z = 6 to z = 7.

  17. Aerodynamic Characteristics of a Circular Cylinder at Mach Number 6.86 and Angles of Attack up to 90 Degrees

    NASA Technical Reports Server (NTRS)

    Penland, Jim A

    1957-01-01

    Pressure-distribution and force tests of a circular cylinder have been made in the Langley 11-inch hypersonic tunnel at a Mach number of 6.88, a Reynolds number of 129,000, and angles of attack up to 90 degrees. The results are compared with the hypersonic approximation of Grimminger, Williams, and Young and a simple modification of the Newtonian flow theory. An evaluation of the crossflow theory is made through comparison of present results with available crossflow Mach number drag coefficients.

  18. Performance and boundary-layer data from 12 degree and 23 degree conical diffusers of area ratio 2.0 at Mach numbers up to choking and Reynolds numbers up to 7.5 x 10(6)

    NASA Technical Reports Server (NTRS)

    Little, B H , Jr; Wilbur, Stafford W

    1954-01-01

    For each of two inlet-boundary-layer thicknesses, performance and boundary-layer characteristics have been determined for a 12 degree, 10-inch-inlet-diameter diffuser, a 12 degree, 21-inch-inlet-diameter diffuser, and a 23 degree, 21-inch-inlet-diameter diffuser. The investigation covered an inlet Mach number range from about 0.10 to coking. The corresponding inlet Reynolds number, based on inlet diameter, varied from about 0.5 x 10(6) to 7.5 x 10(6).

  19. Effects of 36.6 GHz and static magnetic field on degree of endoreduplication in Drosophila melanogaster polytene chromosomes.

    PubMed

    Dyka, Liliia D; Shakina, Lyubov A; Strashnyuk, Volodymyr Yu; Shckorbatov, Yuriy G

    2016-01-01

    Purpose To study the effect of microwave (MW) irradiation and consistent action of microwaves and static magnetic field (MF) on the giant chromosomes endoreduplication in Drosophila melanogaster Meig. Materials and methods Experiments were carried out on inbred wild type Canton-S strain. Exposure to microwaves (frequency - 36.64 GHz, power density - 1 W/m(2), exposure time - 30 sec) and static magnetic field (intensity - 25 mT, exposure time - 5 min) applied at the egg stage after a 2-h oviposition. Giant chromosomes were investigated in squashed preparations of the salivary glands stained by acetoorcein by the cytomorphometric method. Preparations were obtained from Drosophila larvae at the 0 h prepupae stage. Results Exposure to microwaves increased the degree of polyteny in chromosomes (DPC) by 7.5%, and the statistical power of the impact was: h(2) = 35.3%. A similar effect occurred after the sequential action of microwaves and static magnetic field: The polyteny level of chromosomes increased by 7.4%, statistical power was: h(2) = 30.6%. Conclusions Exposure to microwaves on the stage of embryogenesis has a stimulating effect on endoreduplication in Drosophila development. The effect of microwaves was not modified by the action of the static magnetic field.

  20. SU-D-18A-07: Towards 6-Degree-Of-Freedom Real-Time Motion Management in Cancer Radiotherapy

    SciTech Connect

    Huang, C.Y.; Keall, P; Nasehi Tehrani, J; Booth, J

    2014-06-01

    Purpose: Lung tumor motion has been identified as a major issue that deteriorates treatment efficacy for radiotherapy, especially for SBRT. As tighter PTV margins are applied due to translational compensation, tumor rotation will become the dominant factor limiting tumor targeting accuracy. This is the world-first study quantifies lung tumor rotation by utilizing kV images with fiducial markers and a step towards 6-degree-of-freedom real-time cancer radiotherapy. Methods: Three or four gold coils were implanted as tumor surrogates in 3 lung cancer patients. 50 fractions of 8- minute, 10 Hz 4D CBCT projections were acquired for the patients immediately prior or after radiotherapy. The fiducial marker positions are segmented, reconstructed and used to determine tumour rotation by the iterative closest point algorithm. Different data acceptance and filtering methods were applied to accept data or smooth the marker trajectory. Results: The average rotation angles around the left/ right (LR), superior/inferior (SI), anterior/posterior (AP) rotations were found to be 0.8±4.2, -0.8±4.5 and 1.7±3.1 degrees respectively. For 28% of the treatment time, the lung tumors rotated more than 5° around the SI axis. Respiration-induced rotational motion was detected in 2 of the 3 lung patients. This can be explained by the patient developed atelectasis during the treatment period. Interestingly, no heart beating component of rotation was observed in the power spectrum. Different rotational types were observed within the patient cohort with large variations in the magnitude of the rotation between patients. Conclusions: For the first time, continuous tumor rotation has been measured for lung patients with gold fiducial markers. Tumors were found to undergo rotations of more than 5° for almost a third of the total treatment time. The study also demonstrated the feasibility of using continuously kV images for real-time lung tumour motion adaptive radiotherapy which can potentially

  1. Tenth value layers for 60Co gamma rays and for 4, 6, 10, 15, and 18 MV x rays in concrete for beams of cone angles between 0 degrees and 14 degrees calculated by Monte Carlo simulation.

    PubMed

    Jaradat, Adnan K; Biggs, Peter J

    2007-05-01

    The calculation of shielding barrier thicknesses for radiation therapy facilities according to the NCRP formalism is based on the use of broad beams (that is, the maximum possible field sizes). However, in practice, treatment fields used in radiation therapy are, on average, less than half the maximum size. Indeed, many contemporary treatment techniques call for reduced field sizes to reduce co-morbidity and the risk of second cancers. Therefore, published tenth value layers (TVLs) for shielding materials do not apply to these very small fields. There is, hence, a need to determine the TVLs for various beam modalities as a function of field size. The attenuation of (60)Co gamma rays and photons of 4, 6, 10, 15, and 18 MV bremsstrahlung x ray beams by concrete has been studied using the Monte Carlo technique (MCNP version 4C2) for beams of half-opening angles of 0 degrees , 3 degrees , 6 degrees , 9 degrees , 12 degrees , and 14 degrees . The distance between the x-ray source and the distal surface of the shielding wall was fixed at 600 cm, a distance that is typical for modern radiation therapy rooms. The maximum concrete thickness varied between 76.5 cm and 151.5 cm for (60)Co and 18 MV x rays, respectively. Detectors were placed at 630 cm, 700 cm, and 800 cm from the source. TVLs have been determined down to the third TVL. Energy spectra for 4, 6, 10, 15, and 18 MV x rays for 10 x 10 cm(2) and 40 x 40 cm(2) field sizes were used to generate depth dose curves in water that were compared with experimentally measured values.

  2. The Tech Prep Associate Degree Challenge: A Report of the Tech Prep Roundtable. AACC Special Reports No. 6.

    ERIC Educational Resources Information Center

    Falcone, Lisa, Ed.; Mundhenk, Robert, Ed.

    In fall 1993, a roundtable was held with leading Tech Prep practitioners to discuss the direction Tech Prep has taken since 1990 and emerging issues related to the implementation of Tech Prep Associate Degree (TPAD) programs. Stemming from the roundtable, this monograph describes Tech Prep, provides recommendations for implementation, and…

  3. Analog Simulation of a Single Degree of Freedom System with Nonlinear Damping. COED Transactions, Vol. VIII, No. 6, June 1976.

    ERIC Educational Resources Information Center

    Hirsch, Richard A.

    A computer project in the area of equivalent viscous damping is described. The concept of equivalent viscous damping is applied to a single-degree-of-freedom system with velocity-squared damping. Comparison of the analytical results with an analog computer solution shows that the concept gives accurate results for the amplitude and phase of the…

  4. 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.

  5. EIGEN-6C4 - The latest combined global gravity field model including GOCE data up to degree and order 1949 of GFZ Potsdam and GRGS Toulouse

    NASA Astrophysics Data System (ADS)

    Förste, Christoph; Bruinsma, Sean; Abrikosov, Oleg; Flechtner, Frank; Marty, Jean-Charles; Lemoine, Jean-Michel; Dahle, Christoph; Neumayer, Hans; Barthelmes, Franz; König, Rolf; Biancale, Richard

    2014-05-01

    GFZ Potsdam and GRGS Toulouse have a long-time close cooperation in the field of global gravity field determination. Here we focus on (1) GOCE gravity field determination and (2) computation of high resolution combined gravity field models. Such data products play a fundamental role in geodesy and Earth sciences, ranging from practical purposes, like precise orbit determination, to scientific applications, like investigations of the density structure of the Earth's interior. Here we present our combined gravity field model EIGEN-6C4 which is the fourth release of EIGEN-6C (EIGEN = European Improved Gravity model of the Earth by New techniques). The first release of EIGEN-6C, published in 2011, was the first global combined gravity field model containing GOCE data. It was computed from a combination of LAGEOS, GRACE and GOCE data, augmented with DTU10 surface gravity data, and it is complete to degree and order 1440 (corresponding to 14 km spatial resolution). The combination of the different data types has been done on the basis of full normal equations up to maximum degree/order 370. The spherical harmonic coefficients of the shorter wavelengths were obtained from a block diagonal normal equation from the terrestrial data only. The subsequent releases EIGEN-6C2 (2012) and EIGEN-6C3stat (2013) were complete to degree and order 1949 (corresponding to approx. 10 km spatial resolution) and comprise extended measurement time spans for the LAGEOS/GRACE as well as for the GOCE data. Now we present the new release EIGEN-6C4. This time variable combined gravity field model is again developed to degree and order 1949 and comprises the new GRACE Release 03 from GRGS and gradiometer data almost of the entire GOCE mission (Sept. 2009-Sept. 2013). Our combination of GRACE and GOCE data allows the construction of an accurate satellite-only contribution to the final combined model up to degree and order 260, where the GOCE gradiometer data contribute only for degrees upwards of

  6. 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,…

  7. Mach 6 experimental and theoretical stability and performance of a cruciform missile at angles of attack up to 65 degrees

    NASA Technical Reports Server (NTRS)

    Hartman, Edward R.; Johnston, Patrick J.

    1987-01-01

    An experimental and theoretical investigation of the longitudinal and lateral-directional stability and control of an axisymmetric cruciform-finned missile has been conducted at Mach 6. The angle-of-attack range extended from 20 to 65 deg to encompass maximum lift. Longitudinal stability, performance, and trim could be accurately predicted with the fins at a fin roll angle of 0 deg but not when the fins were at a fin roll angle of 45 deg. At this roll angle, windward fin choking occurred at angles of attack above 50 deg and reduced the effectiveness of the fins and caused pitch-up.

  8. Attachment-Line Transition Due to Roughness on a 76 Degree Swept Cylinder at Mach 1.6

    NASA Technical Reports Server (NTRS)

    Coleman, Colin P.; Poll, D. I. A.

    1998-01-01

    Experiments were conducted on a 76 deg. swept cylinder to establish the conditions for the attachment-line transition process with, and without, surface roughness in a low-disturbance ("quiet"), Mach number 1.6 flow. Local flow parameters were estimated from pressure measurements. These were in good agreement with predictions from an Euler code (CFL3D) and a boundary layer code (BL3D). Hot-wires and Schlieren photography were used to determine the state of the boundary layer. It was found that, for a near-adiabatic wall condition and a smooth surface, the attachment-line, boundary-layer remained laminar up to the highest attainable Reynolds number (R-bar of 790). Transition under the influence of trip wires was found to depend on wind-tunnel disturbance levels and the onset conditions have been established. Results suggest that current design practice, which is based upon data from conventional ("noisy") tunnels, may be highly conservative.

  9. Dishonorary Degrees

    ERIC Educational Resources Information Center

    Romano, Carlin

    2008-01-01

    If an honorary degree lacks values to begin with, does withdrawing it deliver a rebuke to the recipient? Is whatever honor that comes with the distinction embedded in the fancy paper, or is it wholly in the eye of the degree holder? Are honorary degrees really such silly things that individuals should mock their bestowal or withdrawal? The case of…

  10. Apparent molar volumes of aqueous calcium chloride to 250{degrees}C, 400 bars, and from molalities of 0.242 to 6.150

    SciTech Connect

    Oakes, C.S.; Bodnar, R.J.; Simonson, J.M.

    1995-09-01

    Relative densities of CaCl{sub 2}(aq) with 0.242 {le} m/(mol-kg{sup {minus}1}) {le} 6.150 were measured with vibrating-tube densimeters between 25 and 250{degrees}C and near 70 and 400 bars. Apparent molar volumes V{sub {null}} calculated from the measured density differences were represented with the Pitzer ion-interaction treatment, with appropriate expressions chosen for the temperature and pressure dependence of the virial coefficients of the model. It was found that the partial molar volume at infinite dilution V{sub {null}}{sup o}, and the second and third virial coefficients B{sup v} and C{sup v}, were necessary to represent V{sub {null}} near the estimated experimental uncertainty. The ionic-strength dependent {Beta}{sup 1}{sup v} term in the B{sup v} coefficient was included in the fit. The representation for V{sub {null}} has been integrated with respect to pressure to establish the pressure dependence of excess free energies over the temperature range studied. The volumetric data indicate that the logarithm of the mean ionic activity coefficient, ln {gamma}{plus_minus}(CaCl{sub 2}), increases by a maximum of 0.3 at 400 bars, 250{degrees}C, and 6 mol-kg{sup {minus}1} as compared with its value at saturation pressure.

  11. A higher degree of methylation of the HPV 16 E6 gene is associated with a lower likelihood of being diagnosed with cervical intraepithelial neoplasia

    PubMed Central

    Piyathilake, Chandrika J.; Macaluso, Maurizio; Alvarez, Ronald D.; Chen, Min; Badiga, Suguna; Edberg, Jeffrey C; Partridge, Edward E; Johanning, Gary L

    2010-01-01

    Background Even though HPV 16 is the most common HPV genotype associated with cancerous lesions of the cervix, only a fraction of HPV 16 infected women are diagnosed with pre-cancerous lesions of the cervix. Therefore, molecular changes in HPV 16 rather than infections per se may serve as better screening or diagnostic biomarkers. The purpose of the study was to evaluate whether methylation status of specific regions of the HPV E6 gene promoter and enhancer is independently associated with the likelihood of being diagnosed with higher grades of cervical intraepithelial neoplasia (CIN 2+). Methods The study included 75 HPV 16 positive women diagnosed with CIN 2+ or ≤ CIN 1. Pyrosequencing technology was applied to quantify methylation at 6 cytosine guanine dinucleotide (CpG) sites of the HPV 16 E6 promoter and enhancer. CIN 2+ (yes/no) was the dependent variable in logistic regression models that specified the degree of methylation of the CpG sites of the HPV 16 E6 gene as the primary independent predictors. All models were adjusted for demographic, lifestyle, known risk factors for cervical cancer and circulating concentrations of “cancer-protective” micronutrients. Results The odds of being diagnosed with CIN 2+ was 79% lower when the degree of methylation of the HPV 16 enhancer and promoter sites were ≥9.5% (OR= 0.21; 95% CI, 0.06–0.79; P=0.02). Conclusions Results suggested that CpG methylation is independently involved in the biology of HPV-16 as well as in the development of higher grades of CIN. PMID:20945322

  12. Measurement of six degrees of freedom head kinematics in impact conditions employing six accelerometers and three angular rate sensors (6aω configuration).

    PubMed

    Kang, Yun-Seok; Moorhouse, Kevin; Bolte, John H

    2011-11-01

    The ability to measure six degrees of freedom (6 DOF) head kinematics in motor vehicle crash conditions is important for assessing head-neck loads as well as brain injuries. A method for obtaining accurate 6 DOF head kinematics in short duration impact conditions is proposed and validated in this study. The proposed methodology utilizes six accelerometers and three angular rate sensors (6aω configuration) such that an algebraic equation is used to determine angular acceleration with respect to the body-fixed coordinate system, and angular velocity is measured directly rather than numerically integrating the angular acceleration. Head impact tests to validate the method were conducted using the internal nine accelerometer head of the Hybrid III dummy and the proposed 6aω scheme in both low (2.3 m/s) and high (4.0 m/s) speed impact conditions. The 6aω method was compared with a nine accelerometer array sensor package (NAP) as well as a configuration of three accelerometers and three angular rate sensors (3aω), both of which have been commonly used to measure 6 DOF kinematics of the head for assessment of brain and neck injuries. The ability of each of the three methods (6aω, 3aω, and NAP) to accurately measure 6 DOF head kinematics was quantified by calculating the normalized root mean squared deviation (NRMSD), which provides an average percent error over time. Results from the head impact tests indicate that the proposed 6aω scheme is capable of producing angular accelerations and linear accelerations transformed to a remote location that are comparable to that determined from the NAP scheme in both low and high speed impact conditions. The 3aω scheme was found to be unable to provide accurate angular accelerations or linear accelerations transformed to a remote location in the high speed head impact condition due to the required numerical differentiation. Both the 6aω and 3aω schemes were capable of measuring accurate angular displacement while the

  13. Prostate-specific antigen 10–20 ng/mL: A predictor of degree of upgrading to ≥8 among patients with biopsy Gleason score 6

    PubMed Central

    Santok, Glen Denmer R.; Abdel Raheem, Ali; Kim, Lawrence HC; Chang, Kidon; Lum, Trenton GH; Chung, Byung Ha; Choi, Young Deuk

    2017-01-01

    Purpose This study aimed to identify the predictors of upgrading and degree of upgrading among patients who have initial Gleason score (GS) 6 treated with robot-assisted radical prostatectomy (RARP). Materials and Methods A retrospective review of the data of 359 men with an initial biopsy GS 6, localized prostate cancer who underwent RARP between July 2005 to June 2010 was performed. They were grouped into group 1 (nonupgrade) and group 2 (upgraded) based on their prostatectomy specimen GS. Logistic regression analysis of studied cases identified significant predictors of upgrading and the degree of upgrading after RARP. Results The mean age and prostate-specific antigen (PSA) was 63±7.5 years, 8.9±8.77 ng/mL, respectively. Median follow-up was 59 months (interquartile range, 47–70 months). On multivariable analysis, age, PSA, PSA density and ≥2 cores positive were predictors of upgrading with (odds ratio [OR], 1.03; 95% confidence interval [CI], 1.01–1.06; p=0.003; OR, 1.006; 95% CI, 1.01–1.11; p=0.018; OR, 0.65; 95% CI, 0.43–0.98, p=0.04), respectively. On subanalysis, only PSA level of 10–20 ng/mL is associated with upgrading into GS ≥8. They also had lower biochemical recurrence free survival, cancer specific survival, and overall survival (p≤0.001, p=0.003, and p=0.01, respectively). Conclusions Gleason score 6 patients with PSA (10–20 ng/mL) have an increased risk of upgrading to pathologic GS (≥8), subsequently poorer oncological outcome thus require a stricter follow-up. These patients should be carefully counseled in making an optimal treatment decision. PMID:28261677

  14. The LP-ESP(®) lumbar disc prosthesis with 6 degrees of freedom: development and 7 years of clinical experience.

    PubMed

    Lazennec, Jean-Yves; Aaron, Alain; Brusson, Adrien; Rakover, Jean-Patrick; Rousseau, Marc-Antoine

    2013-02-01

    The viscoelastic lumbar disk prosthesis-elastic spine pad (LP-ESP(®)) is an innovative one-piece deformable but cohesive interbody spacer providing 6 full degrees of freedom about the 3 axes, including shock absorption. A 20-year research program has demonstrated that this concept provides mechanical properties very close to those of a natural disk. Improvements in technology have made it possible to solve the problem of the bond between the elastic component and the titanium endplates and to obtain an excellent biostability. The prosthesis geometry allows limited rotation and translation with resistance to motion (elastic return property) aimed at avoiding overload of the posterior facets. The rotation center can vary freely during motion. It thus differs substantially from current prostheses, which are 2- or 3-piece devices involving 1 or 2 bearing surfaces and providing 3 or 5 degrees of freedom. This design and the adhesion-molding technology differentiate the LP-ESP prosthesis from other mono-elastomeric prostheses, for which the constraints of shearing during rotations or movement are absorbed at the endplate interface. Seven years after the first implantation, we can document in a solid and detailed fashion the course of clinical outcomes and the radiological postural and kinematic behavior of this prosthesis.

  15. Design improvement of the three-beam detector towards a precise long-range 6-degree of freedom motion sensor system

    SciTech Connect

    Kim, Young-Keun; Kim, Kyung-Soo Kim, Soohyun; Jang, In Gwun

    2014-01-15

    This paper presents performance enhancement of the three beam detector through design improvement based on the error analysis. The three-beam detector is a novel sensor system that measures six motions (i.e., 3 translations and 3 rotations) of a remote object with high accuracy by implementing three laser distance sensors and a vision sensor. In this paper, finite element analysis and parameter analysis are applied to the three-beam detector to analyze its structural frames and sensor configuration, respectively, in terms of sensing error. By virtue of such a systematic, quantitative error analysis, this research has successfully improved the performance of the three-beam detector and thoroughly validated through field tests that it can detect the 6-degree of freedom motions of a remote target at 30 m with an accuracy of 1.51 mm and 0.18° and precision of 0.38 mm and 0.13°.

  16. The influence of a 6.5% carbohydrate-electrolyte solution on performance of prolonged intermittent high-intensity running at 30 degrees C.

    PubMed

    Morris, John G; Nevill, Mary E; Thompson, Dylan; Collie, Jason; Williams, Clyde

    2003-05-01

    Nine male student games players consumed either flavoured water (0.1 g carbohydrate, Na+ 6 mmol x l(-1)), a solution containing 6.5% carbohydrate-electrolytes (6.5 g carbohydrate, Na+ 21 mmol x l(-1)) or a taste placebo (Na+ 2 mmol x l(-1)) during an intermittent shuttle test performed on three separate occasions at an ambient temperature of 30 degrees C (dry bulb). The test involved five 15-min sets of repeated cycles of walking and variable speed running, each separated by a 4-min rest (part A of the test), followed by 60 s run/60 s rest until exhaustion (part B of the test). The participants drank 6.5 ml x kg(-1) of fluid as a bolus just before exercise and thereafter 4.5 ml x kg(-1) during every exercise set and rest period (19 min). There was a trial order effect. The total distance completed by the participants was greater in trial 3 (8441 +/- 873 m) than in trial 1 (6839 +/- 512, P < 0.05). This represented a 19% improvement in exercise capacity. However, the trials were performed in a random counterbalanced order and the participants completed 8634 +/- 653 m, 7786 +/- 741 m and 7099 +/- 647 m in the flavoured water (FW), placebo (P) and carbohydrate-electrolyte (CE) trials, respectively (P = 0.08). Sprint performance was not different between the trials but was impaired over time (FW vs P vs CE: set 1, 2.41 +/- 0.02 vs 2.39 +/- 0.03 vs 2.39 +/- 0.03 s; end set, 2.46 +/- 0.03 vs 2.47 +/- 0.03 vs 2.47 +/- 0.02 s; main effect time, P < 0.01). The rate of rise in rectal temperature was greater in the carbohydrate-electrolyte trial (rise in rectal temperature/duration of trial, degrees C x h(-1); FW vs CE, P < 0.05; P vs CE, N.S.). Blood glucose concentrations were higher in the carbohydrate-electrolyte than in the other two trials (FW vs P vs CE:rest, 4.4 +/- 0.1 vs 4.3 +/- 0.1 vs 4.2 +/- 0.1 mmol x l(-1); end of exercise, 5.4 +/- 0.3 vs 6.4 +/- 0.6 vs 7.2 +/- 0.5 mmol x l(-1); main effect trial, P < 0.05; main effect time, P < 0.01). Plasma free fatty acid

  17. Aerodynamic Characteristics of a Circular Cylinder at Mach Number of 6.86 and Angles of Attack up to 90 Degrees

    NASA Technical Reports Server (NTRS)

    Penland, Jim A

    1954-01-01

    Pressure-distribution and force tests of a circular cylinder have been made in the Langley 11-inch hypersonic tunnel at a Mach number of 6.86, a Reynolds number of 129,000 based on diameter, and angles of attack up to 90 degrees. The results are compared with the hypersonic approximation of Grimminger, Williams, and Young and with a simple modification of the Newtonian flow theory. The comparison of experimental results shows that either theory gives adequate general aerodynamic characteristics but that the modified Newtonian theory gives a more accurate prediction of the pressure distribution. The calculated crossflow drag coefficients plotted as a function of crossflow Mach number were found to be in reasonable agreement with similar results obtained from other investigations at lower supersonic Mach numbers. Comparison of the results of this investigation with data obtained at a lower Mach number indicates that the drag coefficient of a cylinder normal to the flow is relatively constant for Mach numbers above about 4.

  18. Dissolution kinetics of granular calcium carbonate in concentrated aqueous sodium dichromate solution at pH 6.0-7.0 and 110-130 degrees C.

    PubMed

    Wang, Tiangui; Li, Zuohu

    2005-01-01

    An understanding of the factors controlling calcite dissolution is important for modeling geochemical cycles and impacts of greenhouse gases on climate, diagenesis of sediments, and sedimentary rocks. It also has practical significance in the investigation of behavior of carbonates in petroleum and natural gas reservoirs and in the preservation of buildings and monuments constructed from limestone and marble. A large number of papers have been published on dissolution kinetics of calcium carbonate in aqueous solutions. But few involved the near-equilibrium region, especially at elevated temperatures and in concentrated solutions. In this paper, the dissolution kinetics of calcium carbonate in concentrated aqueous sodium dichromate solutions at pH 6.0-7.0 and 110-130 degrees C were studied in a 2-L autoclave. The results indicate that the dissolution reaction is mix-controlled, with surface reaction as the prevailing factor. The concentration of calcium ions in solution hardly affects the dissolution rate, but carbon dioxide in the vapor phase inhibits the dissolution reaction. The dissolution rate can be expressed by R = k(1)a(2)(H+) + k(2), and the apparent activation energy is 55-84 kJ mol(-1).

  19. Oral Skills in the Modern Languages Degree. Proceedings of a Conference at the University of Bradford (Bradford, England, January 3-6, 1984).

    ERIC Educational Resources Information Center

    Doble, Gordon, Ed.; Griffiths, Brian T., Ed.

    The conference proceedings include the opening address, plenary session papers, workshop reports, a final forum and address, and the conference program and participant list. The plenary session papers include: "What Are We Doing in Modern Languages Today?"; "Communicative Skills and the Modern Languages Degree"; "The Place of Spoken Language in…

  20. Psychrophilic (6--15 {degree}C) high-rate anaerobic treatment of malting wastewater in a two-module expanded granular sludge bed system

    SciTech Connect

    Rebac, S.; Lier, J.B. van; Lens, P.; Cappellen, J. van; Vermeulen, M.; Stams, A.J.M.; Lettinga, G.; Dekkers, F.; Swinkels, K.T.M.

    1998-11-01

    Psychrophilic (6--15 C) anaerobic treatment of malting wastewater was investigated. A two-module expanded granular sludge bed reactor system with a total volume of 140 dm{sup 3} was used to treat malting wastewater having a soluble and total chemical oxygen demand (COD) between 233 and 1778 mg dm{sup {minus}3} and between 317 and 4422 mg dm{sup {minus}3}, respectively. The removal efficiencies at 6 C were 47 and 71% of the soluble and volatile fatty acids (VFA) COD, at organic loading rates (OLR) ranging between 3.3 and 5.8 kg of COD m{sup {minus}3} day{sup {minus}1}. The removal efficiencies at 10--15 C were 67--78 and 90--96% of the soluble and VFA COD at an OLR between 2.8 and 12.3 kg of COD m{sup {minus}3} day{sup {minus}1}. The specific methanogenic activity of the sludge present in each module increased 2--3-fold during system operation for 400 days. The relatively high concentration of suspended solids in the influent (25% of the total COD) caused a deterioration of the sludge bed in the first reactor module. This was aggravated by excessive growth of acidifying biomass, which persisted in the first module sludge bed and resulted in granular sludge flotation. However, the second module could accommodate the increased OLR, this providing a very high effluent quality (soluble COD < 200 mg dm{sup {minus}3}) of the total system. The stability of module 1 concerning suspended solids could be restored by presettling the wastewater.

  1. Your College Degree: The External Degree Way.

    ERIC Educational Resources Information Center

    Haponski, William C.; And Others

    Information on undertaking an external degree program to obtain a college education is presented. An external degree program is one that has no, or minimal requirements for residence (on-campus attendance). Most often it can be entered at any time of the year and usually grants credit for documented learning already acquired. An external degree…

  2. The External Degree.

    ERIC Educational Resources Information Center

    Houle, Cyril O.

    This book examines the external degree in relation to the extremes of attitudes, myths, and data. Emphasis is placed on the emergence of the American external degree, foreign external-degree programs, the purpose of the external degree, the current scene, institutional issues, and problems of general policy. (MJM)

  3. 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

  4. Growing degree day calculator

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Degree-day benchmarks indicate discrete biological events in the development of insect pests. For the Sparganothis fruitworm, we have isolated all key development events and linked them to degree-day accumulations. These degree-day accumulations can greatly improve treatment timings for cranberry IP...

  5. Associate Degree Preferred.

    ERIC Educational Resources Information Center

    Parnell, Dale, Ed.

    Designed to encourage dialogue and inform decision making about the associate degree, this book presents perspectives on the role of the associate degree in the nation's two-year colleges. First, "Toward a Greater Degree: A Plan of Action," by Dale Parnell, suggests a plan for preserving and enhancing the value of the education being provided by…

  6. GATEWAYS: Degree program alternatives

    SciTech Connect

    Strong, K.R.; Thayer, M.M.

    1991-11-01

    Los Alamos National Laboratory is using non-traditional solutions to assist employees in attaining degrees required for essential Laboratory operations. Varieties of distance learning technologies have been implemented to meet some degree needs. While distance learning is not always a perfect solution, it enables the Laboratory to provide education that would otherwise not be practical for full-time employees. The Laboratory has also formed partnerships with local colleges to design programs to fill particular needs. Meeting the challenge of providing cost-effective, viable degree programs in an isolated location requires both patience and innovation.

  7. Characteristics of energy exchange between inter- and intramolecular degrees of freedom in crystalline 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) with implications for coarse-grained simulations of shock waves in polyatomic molecular crystals.

    PubMed

    Kroonblawd, Matthew P; Sewell, Thomas D; Maillet, Jean-Bernard

    2016-02-14

    In this report, we characterize the kinetics and dynamics of energy exchange between intramolecular and intermolecular degrees of freedom (DoF) in crystalline 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). All-atom molecular dynamics (MD) simulations are used to obtain predictions for relaxation from certain limiting initial distributions of energy between the intra- and intermolecular DoF. The results are used to parameterize a coarse-grained Dissipative Particle Dynamics at constant Energy (DPDE) model for TATB. Each TATB molecule in the DPDE model is represented as an all-atom, rigid-molecule mesoparticle, with explicit external (molecular translational and rotational) DoF and coarse-grained implicit internal (vibrational) DoF. In addition to conserving linear and angular momentum, the DPDE equations of motion conserve the total system energy provided that particles can exchange energy between their external and internal DoF. The internal temperature of a TATB molecule is calculated using an internal equation of state, which we develop here, and the temperatures of the external and internal DoF are coupled using a fluctuation-dissipation relation. The DPDE force expression requires specification of the input parameter σ that determines the rate at which energy is exchanged between external and internal DoF. We adjusted σ based on the predictions for relaxation processes obtained from MD simulations. The parameterized DPDE model was employed in large-scale simulations of shock compression of TATB. We show that the rate of energy exchange governed by σ can significantly influence the transient behavior of the system behind the shock.

  8. Characteristics of energy exchange between inter- and intramolecular degrees of freedom in crystalline 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) with implications for coarse-grained simulations of shock waves in polyatomic molecular crystals

    SciTech Connect

    Kroonblawd, Matthew P.; Sewell, Thomas D.; Maillet, Jean-Bernard

    2016-02-14

    In this report, we characterize the kinetics and dynamics of energy exchange between intramolecular and intermolecular degrees of freedom (DoF) in crystalline 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). All-atom molecular dynamics (MD) simulations are used to obtain predictions for relaxation from certain limiting initial distributions of energy between the intra- and intermolecular DoF. The results are used to parameterize a coarse-grained Dissipative Particle Dynamics at constant Energy (DPDE) model for TATB. Each TATB molecule in the DPDE model is represented as an all-atom, rigid-molecule mesoparticle, with explicit external (molecular translational and rotational) DoF and coarse-grained implicit internal (vibrational) DoF. In addition to conserving linear and angular momentum, the DPDE equations of motion conserve the total system energy provided that particles can exchange energy between their external and internal DoF. The internal temperature of a TATB molecule is calculated using an internal equation of state, which we develop here, and the temperatures of the external and internal DoF are coupled using a fluctuation-dissipation relation. The DPDE force expression requires specification of the input parameter σ that determines the rate at which energy is exchanged between external and internal DoF. We adjusted σ based on the predictions for relaxation processes obtained from MD simulations. The parameterized DPDE model was employed in large-scale simulations of shock compression of TATB. We show that the rate of energy exchange governed by σ can significantly influence the transient behavior of the system behind the shock.

  9. Degree by Thesis

    ERIC Educational Resources Information Center

    Courtis, Barbara

    1974-01-01

    Discusses a student's experience with a research project on the synthesis and reactions of an organo-platinum complex with an organo-Group IV linkage, including the advantages and disadvantages of such a degree by thesis course. (CC)

  10. The "Clinical" Masters Degree.

    ERIC Educational Resources Information Center

    Perlman, Baron; Lane, Robert

    1981-01-01

    Discusses issues surrounding the clinical master's degree: the belief that the only true psychologist is a PhD, public confusion between doctoral and subdoctoral psychologists, training guidelines, role responsibility, employment, licensing and competency, accreditation, and supervision. Suggests an APA sponsored conference to discuss and resolve…

  11. Registered Nurse (Associate Degree).

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Center on Education and Training for Employment.

    This document, which is designed for use in developing a tech prep competency profile for the occupation of registered nurse (with an associate degree), lists technical competencies and competency builders for 19 units pertinent to the health technologies cluster in general and 5 units specific to the occupation of registered nurse. The following…

  12. Six degree of freedom sensor

    DOEpatents

    Vann, Charles S.

    1999-01-01

    This small, non-contact optical sensor increases the capability and flexibility of computer controlled machines by detecting its relative position to a workpiece in all six degrees of freedom (DOF). At a fraction of the cost, it is over 200 times faster and up to 25 times more accurate than competing 3-DOF sensors. Applications range from flexible manufacturing to a 6-DOF mouse for computers. Until now, highly agile and accurate machines have been limited by their inability to adjust to changes in their tasks. By enabling them to sense all six degrees of position, these machines can now adapt to new and complicated tasks without human intervention or delay--simplifying production, reducing costs, and enhancing the value and capability of flexible manufacturing.

  13. Six degree of freedom sensor

    DOEpatents

    Vann, C.S.

    1999-03-16

    This small, non-contact optical sensor increases the capability and flexibility of computer controlled machines by detecting its relative position to a workpiece in all six degrees of freedom (DOF). At a fraction of the cost, it is over 200 times faster and up to 25 times more accurate than competing 3-DOF sensors. Applications range from flexible manufacturing to a 6-DOF mouse for computers. Until now, highly agile and accurate machines have been limited by their inability to adjust to changes in their tasks. By enabling them to sense all six degrees of position, these machines can now adapt to new and complicated tasks without human intervention or delay--simplifying production, reducing costs, and enhancing the value and capability of flexible manufacturing. 3 figs.

  14. Characteristics of Louisiana State University Master's Degree Graduates in School Administration and Their Perceptions of Their Academic Preparation, 1971-76. Research Report Vol. 7, No. 6, September 1977.

    ERIC Educational Resources Information Center

    Gee, Jerry Brooksher; Kilgore, Leonard L.

    A study conducted at Louisiana State University was designed to: determine demographic characteristics of master's degree graduates in school administration in order to draw conclusions concerning identifying profiles; ascertain the extent to which the graduates perceived the courses of instruction in their academic preparation as relevant to…

  15. A comparison of the spanwise loading calculated by various methods with experimental loadings obtained on a 45 degree sweptback wing of aspect ratio 8.02 at a Reynolds number of 4.0 x 10(6)

    NASA Technical Reports Server (NTRS)

    Schneider, Willaim C

    1954-01-01

    This report compares the experimental force and moment data obtained by pressure measurements on a wing of aspect ratio 8.02, 45 degree sweptback of the quarter-chord line, taper ratio of 0.45, and NACA 63sub1a012 airfoil sections with the calculated loadings obtained by the standard methods proposed by Weissinger, Falkner, and Multopp, as well as by several variations of these methods.

  16. When Graduate Degrees Prostitute the Educational Process: Degrees Gone Wild

    ERIC Educational Resources Information Center

    Lumadue, Richard T.

    2006-01-01

    Graduate degrees prostitute the educational process when they are sold to consumers by unaccredited degree/diploma mills as being equivalent to legitimate, bona-fide degrees awarded by accredited graduate schools. This article carefully analyzes the serious problems of bogus degrees and their association with the religious higher education…

  17. Degrees of understanding

    NASA Astrophysics Data System (ADS)

    Carlowicz, Michael

    America's most famous journalism school has teamed up with the Lamont-Doherty Earth Observatory to try to improve science communication. This fall, Columbia University combined two of its greatest assets—Lamont-Doherty and the Columbia School of Journalism—to offer a joint degree program for would-be writers to specialize in Earth and environmental science.“Science journalists are translators between those with the knowledge and those with the need to know,” said Kenneth Goldstein, a professor of journalism at Columbia. “The new Earth and environmental sciences journalism program seeks to produce students who are fluently bilingual in the language of Earth science and the language of public debate.”

  18. Specificities of the Saccharomyces cerevisiae rad6, rad18, and rad52 mutators exhibit different degrees of dependence on the REV3 gene product, a putative nonessential DNA polymerase.

    PubMed

    Roche, H; Gietz, R D; Kunz, B A

    1995-06-01

    The Saccharomyces cerevisiae rad6, rad18, and rad52 mutants exhibit DNA repair deficiencies and distinct mutator phenotypes. DNA replication past unrepaired spontaneous damage might contribute to the specificities of these mutators. Because REV3 is thought to encode a DNA polymerase that specializes in translesion synthesis, we determined the REV3 dependence of the rad mutator specificities. Spontaneous mutagenesis at a plasmid-borne SUP4-o locus was examined in isogenic strains having combinations of normal or mutant REV3 and RAD6, RAD18, or RAD52 alleles. For the rad6 and rad18 mutators, the mutation rate increase relied largely, but not exclusively, on REV3 whereas the rad52 mutator was entirely REV3 dependent. The influence of REV3 on the specificity of the rad6 mutator differed markedly depending on the mutational class examined. However, the requirement of rev3 for the production of G.C-->T.A transversions by the rad18 mutator, which induces only these substitutions, was similar to that for rad6-mediated G.C-->T.A transversion. This supports a role for the Rad6-Rad18 protein complex in the control of spontaneous mutagenesis. The available data imply that the putative Rev3 polymerase can process a variety of spontaneous DNA lesions that normally are substrates for error-free repair.

  19. Twelfth degree spline with application to quadrature.

    PubMed

    Mohammed, P O; Hamasalh, F K

    2016-01-01

    In this paper existence and uniqueness of twelfth degree spline is proved with application to quadrature. This formula is in the class of splines of degree 12 and continuity order [Formula: see text] that matches the derivatives up to order 6 at the knots of a uniform partition. Some mistakes in the literature are pointed out and corrected. Numerical examples are given to illustrate the applicability and efficiency of the new method.

  20. 360-degree Color Panorama

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This is a 'geometrically improved' version of the 360- degree panorama heretofore known as the 'Gallery Pan', the first contiguous, uniform panorama taken by the Imager for Mars Pathfinder (IMP) over the course of Sols 8, 9, and 10. Different regions were imaged at different times over the three Martian days to acquire consistent lighting and shadow conditions for all areas of the panorama.

    The IMP is a stereo imaging system that, in its fully deployed configuration, stands 1.8 meters above the Martian surface, and has a resolution of two millimeters at a range of two meters. In this geometrically improved version of the panorama, distortion due to a 2.5 degree tilt in the IMP camera mast has been removed, effectively flattening the horizon.

    The IMP has color capability provided by 24 selectable filters -- twelve filters per 'eye'. Its red, green, and blue filters were used to take this image.

    At left is a Lander petal and a metallic mast which is a portion of the low-gain antenna. Misregistration in the antenna and other Lander features is due to parallax in the extreme foreground. On the horizon the double 'Twin Peaks' are visible, about 1-2 kilometers away. The rock 'Couch' is the dark, curved rock at right of Twin Peaks. Another Lander petal is at left-center, showing the fully deployed forward ramp at far left, and rear ramp at right, which rover Sojourner used to descend to the surface of Mars on July 5. Immediately to the left of the rear ramp is the rock 'Barnacle Bill', which scientists found to be andesitic, possibly indicating that it is a volcanic rock (a true andesite) or a physical mixture of particles. Just beyond Barnacle Bill, rover tracks lead to Sojourner, shown using its Alpha Proton X-Ray Spectrometer (APXS) instrument to study the large rock 'Yogi'. Yogi, low in quartz content, appears to be more primitive than Barnacle Bill, and appears more like the common basalts found on Earth.

    The tracks and circular pattern in the soil

  1. Two Universities, Two Degrees: A Dual Degree Program for Pharmacists.

    ERIC Educational Resources Information Center

    Milio, Frank

    2001-01-01

    Describes a dual degree program between Towson University and the University of Maryland School of Pharmacy, which allows a student to receive both a B.S. degree in Medicinal Chemistry and a Doctor of Pharmacy degree in a combined 7-year program. It also allows flexibility in pursuing alternate career goals. (EV)

  2. Heat-Transfer Measurements in Free Flight at Mach Numbers up to 14.6 on a Flat-Faced Conical Nose with a Total Angle of 29 Degrees

    NASA Technical Reports Server (NTRS)

    Rumsey, Charles B; Lee, Dorothy B

    1958-01-01

    Skin-temperature measurements have been made at several locations on a flat-faced cone-cylinder nose which was flight tested on a fivestage rocket-propeller model to a Mach number of 14.64 and a free-stream Reynolds number of 2.0 x 10(exp 6), based on flat-face diameter, at an altitude of 66,300 feet. The copper nose had a 29 deg total-angle conical section which was 1.6 flat-face diameters long. The aerodynamic-heating rates determined from the temperature measurements reached 1,440 Btu/( sec) (sq ft) on the flat face. The heating rates near the center of the flat face agreed well at Mach numbers up to 13.6 with those obtained by a theory for laminar stagnation-point heating in equilibrium dissociated air (Avco Res. Rep. 1). At Mach numbers above 13.6, the heating rates at locations near the center of the flat face became progressively lower than stagnation-point theory and. were 29 percent lower at Mach number 14.6 at the end. of the test. The reason for this behavior of the heating on the central part of the flat face was not determined. Excluding the relatively low heating rates that occurred on the central part of the nose at the highest Mach numbers, the distribution of experimental heating along the innermost 0.79 of the flat-face radius, expressed as a percentage of stagnation-point heating, was in fair agreement with the distribution predicted by laminar theory. At a location of 0.71 radii from the stagnation point, the experimental heating was very near 130 percent of the theoretical stagnation-point rate at Mach numbers from 11 to 14.5. The experimental beating rates on the conical section of the nose were in good agreement with laminar-cone theory using the assumption of theoretical sharp-cone static pressure on the conical section.

  3. Foundation Degrees: A Risky Business?

    ERIC Educational Resources Information Center

    Rowley, Jennifer

    2005-01-01

    Purpose: Foundation degrees, the new proposal for sub-degree vocational education in the UK, are characterised by innovation both in their design (curriculum, teaching, learning and assessment) and in the marketplace for which they are designed. This article argues that the development and delivery of foundation degrees carry a high level of risk,…

  4. Students' Perceptions of Foundation Degrees

    ERIC Educational Resources Information Center

    Ooms, A.; Burke, L. M.; Marks-Maran, D. J.; Webb, M.; Cooper, D.

    2012-01-01

    In 2008 there were 87,339 people enrolled on foundation degrees (FDs) in the UK (Foundation Degree Forward, 2009), and educational institutions in the UK offered 1700 different foundation degrees in over 25 subjects, with nearly 900 more in development (Action on Access, 2010). In addition, student views are seen to be of importance, as…

  5. Postgraduation Activities: All Degree Levels in Pennsylvania, 1979.

    ERIC Educational Resources Information Center

    Donny, William F.

    The employment of graduates of all degree levels in Pennsylvania institutions of higher education in 1979 was examined, based on data for 44,875 graduates or 50.6 percent of all higher education graduates. Research was designed to determine what proportion of graduates in each degree field and degree level were employed in their fields of…

  6. Graduate Physics Degrees: Largest Departments and Degree Distribution. Focus On

    ERIC Educational Resources Information Center

    Mulvey, Patrick J.; Nicholson, Starr

    2014-01-01

    In the 2011-12 academic year there were 751 degree-granting physics departments in the U.S. Of these, 195 offered a PhD and 62 departments offered a master's as the highest physics degree. The remaining 494 departments offered a bachelor's as their highest physics degree. There were six universities that had two doctoral-granting physics…

  7. Number density distribution of near-infrared sources on a sub-degree scale in the Galactic center: Comparison with the Fe XXV Kα line at 6.7 keV

    NASA Astrophysics Data System (ADS)

    Yasui, Kazuki; Nishiyama, Shogo; Yoshikawa, Tatsuhito; Nagatomo, Schun; Uchiyama, Hideki; Tsuru, Takeshi Go; Koyama, Katsuji; Tamura, Motohide; Kwon, Jungmi; Sugitani, Koji; Schödel, Rainer; Nagata, Tetsuya

    2015-12-01

    The stellar distribution derived from an H- and KS-band survey of the central region of our Galaxy is compared with the Fe XXV Kα (6.7 keV) line intensity observed with the Suzaku satellite. The survey is for the galactic coordinates |l| ≲ 3.0° and |b | ≲ 1.0° (equivalent to 0.8 kpc × 0.3 kpc for R⊙ = 8 kpc), and the number-density distribution N(KS,0; l, b) of stars is derived by using the extinction-corrected magnitude KS,0 = 10.5. This is deep enough to probe the old red-giant population and in turn to estimate the (l, b) distribution of faint X-ray point sources such as coronally active binaries and cataclysmic variables. In the Galactic plane (b = 0°), N(10.5; l, b) increases in the direction of the Galactic center as |l|-0.30±0.03 in the range of - 0.1° ≥ l ≥ - 0.7°, but this increase is significantly slower than the increase (|l|-0.44±0.02) of the Fe XXV Kα line intensity. If normalized with the ratios in the outer region 1.5° ≤ |l| ≤ 2.8°, where faint X-ray point sources are argued to dominate the diffuse Galactic X-ray ridge emission, the excess of the Fe XXV Kα line intensity over the stellar number density is at least a factor of two at |l| = 0.1°. This indicates that a significant part of the Galactic-center diffuse emission arises from a truly diffuse optically thin thermal plasma, and not from an unresolved collection of faint X-ray point sources related to the old stellar population.

  8. The technology of two degrees

    SciTech Connect

    Jae Edmonds; Steven J. Smith

    2006-02-15

    This paper examines some of the energy technology implications of limiting the change in mean global surface temperature (GMST) to two degrees Celsius (2{sup o}C) relative to pre-industrial temperatures. Understanding the implications of this goal is clouded by uncertainty in key physical science parameters, particularly the climate sensitivity. If the climate sensitivity is 2.5{sup o}C then stabilization implies stabilisation of CO{sub 2} concentrations at less than 500 parts per million (ppm) with a peak in global CO{sub 2} emissions occurring in the next 15 years and with a decline in emissions to approximately 3 petagrams of carbon per year by 2095. Under such circumstances the value of technology improvements beyond those assumed in the reference case is found to be exceptionally high, denominated in trillions of 1990 USD. The role of non-CO{sub 2} greenhouse gases is important. Aerosols could produce significant feedbacks, though uncertainty is significant. If the climate sensitivity is 3.5{sup o}C or greater, it may be impossible to hold GMST change below 2{sup o}C. On the other hand if the climate sensitivity is 1.5{sup o}C, limiting GMST change to 2{sup o}C may be a trivial matter requiring little deviation from a reference emission path until after the middle of the 21st century. 21 refs., 6 figs., 1 tab.

  9. Quaternary Geologic Map of the Regina 4 Degrees x 6 Degrees Quadrangle, United States and Canada

    USGS Publications Warehouse

    Fullerton, David S.; Christiansen, Earl A.; Schreiner, Bryan T.; Colton, Roger B.; Clayton, Lee; Bush, Charles A.; Fullerton, David S.

    2007-01-01

    For scientific purposes, the map differentiates Quaternary surficial deposits and materials on the basis of clast lithology or composition, matrix texture or particle size, structure, genesis, stratigraphic relations, engineering geologic properties, and relative age, as shown on the correlation diagram and indicated in the 'Description of Map Units'. Deposits of some constructional landforms, such as end moraines, are distinguished as map units. Deposits of erosional landforms, such as outwash terraces, are not distinguished, although glaciofluvial, ice-contact, fluvial, and lacustrine deposits that are mapped may be terraced. Differentiation of sequences of fluvial and glaciofluvial deposits at this scale is not possible. For practical purposes, the map is a surficial materials map. Materials are distinguished on the basis of lithology or composition, texture or particle size, and other physical, chemical, and engineering characteristics. It is not a map of soils that are recognized and classified in pedology or agronomy. Rather, it is a generalized map of soils as recognized in engineering geology, or of substrata or parent materials in which pedologic or agronomic soils are formed. As a materials map, it serves as a base from which a variety of maps for use in planning engineering, land-use planning, or land-management projects can be derived and from which a variety of maps relating to earth surface processes and Quaternary geologic history can be derived.

  10. NLN: Celebrating Associate Degree Nursing.

    ERIC Educational Resources Information Center

    Hoddick, Nancy A.

    1981-01-01

    Introduces a project celebrating the thirtieth anniversary of associate degree nursing (ADN) education. Reviews the efforts and plans of two national associations to identify and resolve recurring ADN issues and recognize the associate degree nurse's contributions. Describes the forums and publications planned to meet these objectives. Includes…

  11. Employers Often Distrust Online Degrees

    ERIC Educational Resources Information Center

    Carnevale, Dan

    2007-01-01

    This article explains why employers are reluctant to accept potential employees with online degrees. The results of several surveys of those who evaluate potential employees and make hiring decisions indicate a bias against online degrees, even as more and more colleges are offering programs online. To those officials, the words "online…

  12. Degree, Yes--Education, No

    ERIC Educational Resources Information Center

    Sheahan, Sister Dorothy

    1974-01-01

    The external degree program, based solely on test proficiency, offers to its students not an educational opportunity; not a learning situation but a schema for securing a degree, with any kind of socialization into the profession conspicuously missing from the program. (Author/DS)

  13. Six Degrees of "Visual" Separation

    ERIC Educational Resources Information Center

    Wall, Sharon

    2006-01-01

    Whether referring to psychologist Stanley Milgram's intriguing theory, John Guare's successful play and film, or Kevin Bacon's party game, six degrees of separation may also be used as a way to help students make visual connections. The six degrees of separation is the concept that everyone is connected to everyone else in the world by only six…

  14. Individualized Degree Program Student Handbook.

    ERIC Educational Resources Information Center

    Hagan, Jan

    This student handbook describes the process and components of Whatcom Community College's Individualized Degree Program (IDP), which offers students the opportunity to design an associate degree or certificate plan to meet their educational goals. After introductory material presents a history of the IDP's development and the purpose of the…

  15. Associate/Bachelor Degree Articulation.

    ERIC Educational Resources Information Center

    Hochberg, L. Jim, Sr.

    Policies and procedures to promote articulation of associate degree with bachelor degree study are recommended based on the experience of Hawaii Pacific College, Honolulu. Consideration is given to: flexibility versus rigidity, competency versus curriculum specifics, corroboration and substantiation, and contingency versus once-for-all-award. It…

  16. Guide to Teaching Degrees 2011

    ERIC Educational Resources Information Center

    Adams, Caralee

    2011-01-01

    Getting a master's degree means lots of late nights, busy weekends, and probably taking on student loan debt. The commitment raises the question: Is it worth it? This article takes a comprehensive look at how much a master's is worth, which degree one should pursue, and how one can find a balance in graduate school.

  17. Set our Master's degrees free

    NASA Astrophysics Data System (ADS)

    Padman, Rachael

    2010-04-01

    Making UK undergraduate physics degrees longer must have seemed like a good idea at the time. Back in the early 1990s the standard three-year Bachelor's physics degree (four years in Scotland) was under pressure at both ends. The A-level curriculum - one of the requirements for entry onto a degree course - was being increasingly modularized, and dumbed down. Physics students were arriving at university less well prepared than in the past and there was an increasing awareness that graduates of five-year continental degree courses were better equipped for a professional scientific career than those in the UK. At the same time, local education authorities in the UK were required to provide full funding for a first degree, whether for three or four years.

  18. Center is at Latitude 30 Degrees South, Longitude 210 Degrees

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Center of the orthographic projection is at latitude 30 degrees S., longitude 210 degrees. Toward the top, the lowland plains of Elysium and Utopia Planitiae are separated from the darker heavily cratered highlands by a broad escarpment. The far bottom left is marked by the large light-colored ancient Hellas impact basin. The permanent south polar residual ice cap is located near the bottom.

  19. Killing Horizons Kill Horizon Degrees

    NASA Astrophysics Data System (ADS)

    Bergamin, L.; Grumiller, D.

    Frequently, it is argued that the microstates responsible for the Bekenstein-Hawking entropy should arise from some physical degrees of freedom located near or on the black hole horizon. In this essay, we elucidate that instead entropy may emerge from the conversion of physical degrees of freedom, attached to a generic boundary, into unobservable gauge degrees of freedom attached to the horizon. By constructing the reduced phase space, it can be demonstrated that such a transmutation indeed takes place for a large class of black holes, including Schwarzschild.

  20. Decay resistance of thermally-modified Eucalyptus grandis wood at 140 degrees C, 160 degrees C, 180 degrees C, 200 degrees C and 220 degrees C.

    PubMed

    Calonego, Fred Willians; Severo, Elias Taylor Durgante; Furtado, Edson Luiz

    2010-12-01

    The objective of this study was to evaluate the effect of thermal treatment on the biological resistance of Eucalyptus grandis wood to the decay fungus Picnoporus sanguineus. Boards from 5 years and 11 months old E. grandis trees, taken from the stock possessed by the Duratex-SA company, were thermally-modified at 140 degrees C, 160 degrees C, 180 degrees C, 200 degrees C and 220 degrees C in the Laboratory of Wood Drying and Preservation from UNESP, Botucatu, SP, Brazil. Samples of each treatment were treated according to ASTM D-2017 (1994). The experiment tested the accelerated decay caused by the decay fungus P. sanguineus on a system of soil-block wood. The results of thermal treatment showed that an increase of temperature of 180-220 degrees C caused reductions of between 15.7% and 82.4% in the weight loss in the samples from E. grandis incubated with P. sanguineus.

  1. Comparison of two-stage thermophilic (68 degrees C/55 degrees C) anaerobic digestion with one-stage thermophilic (55 degrees C) digestion of cattle manure.

    PubMed

    Nielsen, H B; Mladenovska, Z; Westermann, P; Ahring, B K

    2004-05-05

    A two-stage 68 degrees C/55 degrees C anaerobic degradation process for treatment of cattle manure was studied. In batch experiments, an increase of the specific methane yield, ranging from 24% to 56%, was obtained when cattle manure and its fractions (fibers and liquid) were pretreated at 68 degrees C for periods of 36, 108, and 168 h, and subsequently digested at 55 degrees C. In a lab-scale experiment, the performance of a two-stage reactor system, consisting of a digester operating at 68 degrees C with a hydraulic retention time (HRT) of 3 days, connected to a 55 degrees C reactor with 12-day HRT, was compared with a conventional single-stage reactor running at 55 degrees C with 15-days HRT. When an organic loading of 3 g volatile solids (VS) per liter per day was applied, the two-stage setup had a 6% to 8% higher specific methane yield and a 9% more effective VS-removal than the conventional single-stage reactor. The 68 degrees C reactor generated 7% to 9% of the total amount of methane of the two-stage system and maintained a volatile fatty acids (VFA) concentration of 4.0 to 4.4 g acetate per liter. Population size and activity of aceticlastic methanogens, syntrophic bacteria, and hydrolytic/fermentative bacteria were significantly lower in the 68 degrees C reactor than in the 55 degrees C reactors. The density levels of methanogens utilizing H2/CO2 or formate were, however, in the same range for all reactors, although the degradation of these substrates was significantly lower in the 68 degrees C reactor than in the 55 degrees C reactors. Temporal temperature gradient electrophoresis profiles (TTGE) of the 68 degrees C reactor demonstrated a stable bacterial community along with a less divergent community of archaeal species.

  2. [Comparative analysis of changes in rats organisms exposed to microgravity and head-down suspension].

    PubMed

    Il'in, E A; Kaplanskiĭ, A S

    1998-01-01

    Comparative analysis of metabolic and structural shifts in rats following 14 days of microgravity aboard biosatellite Cosmos-2044 and their tail-suspended synchronous controls gave evidence that suspension-induced deprivation of hind limbs of support loading yields inherent to microgravity shifts the endocrine control of energy, plastic, and mineral metabolism. The conclusion has been drawn that tail-suspension can be used as a model of the microgravity effects on the musculoskeletal apparatus and the endocrine systems controlling metabolism in muscles and bones.

  3. 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.

  4. A Comparison of Head-Up and Head-Down Display Formats during Instrument Flying Tasks

    DTIC Science & Technology

    1992-11-01

    the radial from the station. The pointer consists of a SA bearing pointer, reference wings, and a readout. The pointer moves about the center of the...indicator to show the relative, magnetic bearing to the TACAN station. The readout displays the magnetic radial itom the i station, The pointer is...center of the Indicator, W 14. 1* W- Figure 4.11 .. Reftrence Tics 4,4,3. TACAN Radial Readout This readout, shown below, displays magnetic radial from

  5. 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).

  6. China and India: The Asian Giants Are Heading Down Different Demographic Paths

    DTIC Science & Technology

    2011-01-01

    reviewed documents. Corporate headquarters 1776 Main Street P.O. Box 2138 Santa Monica, California 90407-2138 tEL 310.393.0411 FAx 310.393.4818...Corporation,National Defense Research Institute,1776 Main Street, P.O. Box 2138, Santa Monica,CA,90407-2138 8. PERFORMING ORGANIZATION REPORT NUMBER 9...Silvia Montoya , MG-1009-OSD, 2011, 170 pp., $28.50, ISBN: 978-0-8330-5042-7 (available at http://www.rand.org/pubs/monographs/MG1009.html). This research

  7. 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.

  8. Life after a Humanities Degree

    ERIC Educational Resources Information Center

    Masola, Athambile

    2016-01-01

    This article explores the experiences of a humanities graduate after leaving the academy. The author considers her own education in light of the historical changes in South Africa's education system. The article is a personal account of the questions and challenges encountered in choosing a humanities degree in a context where a tertiary education…

  9. The Top Theological Degree Producers

    ERIC Educational Resources Information Center

    Diverse: Issues in Higher Education, 2012

    2012-01-01

    Each year, "Diverse: Issues in Higher Education" publishes a list of the Top 100 producers of associate, bachelor's and graduate degrees awarded to minority students based on research conducted by Dr. Victor M. H. Borden, professor of educational leadership and policy studies at Indiana University Bloomington. This year, for the first…

  10. The Top STEM Degree Producers

    ERIC Educational Resources Information Center

    Diverse: Issues in Higher Education, 2012

    2012-01-01

    This article presents a list of the top Science, Technology, Engineering, and Mathematics (STEM) degree producers in the U.S. This list is broken down into seven categories: (1) Total Minority Research/Scholarship and Other Doctoral: Mathematics and Statistics; (2) Total Minority Bachelors: Biological and Biomedical Sciences; (3) Total Minority…

  11. Mississippi Degree Programs: A Numerical (CIP) and Summary Listing of Academic Degree Programs.

    ERIC Educational Resources Information Center

    Mississippi State Board of Trustees of State Institutions of Higher Learning, Jackson.

    This publication presents a numerical and summary listing of academic degree programs at Mississippi State institutions of higher education. Programs are listed by discipline. Program levels include: bachelor's degree, master's degree, specialist degree, sixth year degree, doctoral degree, first professional degree, associate degree, and…

  12. Space Separatism: Degree of Differentiation

    DTIC Science & Technology

    2014-12-01

    November–December 2014 Air & Space Power Journal | 17 Feature Space Separatism Degree of Differentiation Capt Luke R. Stover, USAF Dr. Alan Johnson...expressed or implied in the Journal are those of the authors and should not be construed as carry- ing the official sanction of the Department of...Defense, Air Force, Air Education and Training Command, Air University, or other agencies or departments of the US government. This article may be

  13. Degree Attainment. Snapshot™ Report, Winter 2015

    ERIC Educational Resources Information Center

    National Student Clearinghouse, 2015

    2015-01-01

    This Snapshot Report presents information on student degree attainment in science and engineering disciplines for 2004 and 2014. It offers data on the following: (1) Science and Engineering Degrees as Percentage of All Degrees; (2) Gender Distribution of Science and Engineering Degrees by Level; (3) Gender Distribution of Bachelor's Degrees in…

  14. MC-6 Casius Region

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Mars digital-image mosaic merged with color of the MC-6 quadrangle, Casius region of Mars. Except for the highly dissected southwestern part, which contains faults, mesas, and buttes of Nilosyrtis Mensae, the Casius region is dominated by light-colored and dark, relatively smooth plains. Latitude range 30 to 65 degrees, longitude range -120 to -60 degrees.

  15. The Kilo-Degree Survey

    NASA Astrophysics Data System (ADS)

    de Jong, J. T. A.; Kuijken, K.; Applegate, D.; Begeman, K.; Belikov, A.; Blake, C.; Bout, J.; Boxhoorn, D.; Buddelmeijer, H.; Buddendiek, A.; Cacciato, M.; Capaccioli, M.; Choi, A.; Cordes, O.; Covone, G.; Dall'Ora, M.; Edge, A.; Erben, T.; Franse, J.; Getman, F.; Grado, A.; Harnois-Deraps, J.; Helmich, E.; Herbonnet, R.; Heymans, C.; Hildebrandt, H.; Hoekstra, H.; Huang, Z.; Irisarri, N.; Joachimi, B.; Köhlinger, F.; Kitching, T.; La Barbera, F.; Lacerda, P.; McFarland, J.; Miller, L.; Nakajima, R.; Napolitano, N. R.; Paolillo, M.; Peacock, J.; Pila-Diez, B.; Puddu, E.; Radovich, M.; Rifatto, A.; Schneider, P.; Schrabback, T.; Sifon, C.; Sikkema, G.; Simon, P.; Sutherland, W.; Tudorica, A.; Valentijn, E.; van der Burg, R.; van Uitert, E.; van Waerbeke, L.; Velander, M.; Kleijn, G. V.; Viola, M.; Vriend, W.-J.

    2013-12-01

    The Kilo-Degree Survey (KiDS), a 1500-square-degree optical imaging survey with the recently commissioned OmegaCAM wide-field imager on the VLT Survey Telescope (VST), is described. KiDS will image two fields in u-,g-,r- and i-bands and, together with the VIKING survey, produce nine-band (u- to K-band) coverage over two fields. For the foreseeable future the KiDS/VIKING combination of superb image quality with wide wavelength coverage will be unique for surveys of its size and depth. The survey has been designed to tackle some of the most fundamental questions of cosmology and galaxy formation of today. The main science driver is mapping the dark matter distribution in the Universe and putting constraints on the expansion of the Universe and the equation of state of dark energy, all through weak gravitational lensing. However, the deep and wide imaging data will facilitate a wide variety of science cases.

  16. Optimal Degrees of Synaptic Connectivity.

    PubMed

    Litwin-Kumar, Ashok; Harris, Kameron Decker; Axel, Richard; Sompolinsky, Haim; Abbott, L F

    2017-03-08

    Synaptic connectivity varies widely across neuronal types. Cerebellar granule cells receive five orders of magnitude fewer inputs than the Purkinje cells they innervate, and cerebellum-like circuits, including the insect mushroom body, also exhibit large divergences in connectivity. In contrast, the number of inputs per neuron in cerebral cortex is more uniform and large. We investigate how the dimension of a representation formed by a population of neurons depends on how many inputs each neuron receives and what this implies for learning associations. Our theory predicts that the dimensions of the cerebellar granule-cell and Drosophila Kenyon-cell representations are maximized at degrees of synaptic connectivity that match those observed anatomically, showing that sparse connectivity is sometimes superior to dense connectivity. When input synapses are subject to supervised plasticity, however, dense wiring becomes advantageous, suggesting that the type of plasticity exhibited by a set of synapses is a major determinant of connection density.

  17. Enrollments and Degrees Report. AIP Report.

    ERIC Educational Resources Information Center

    Mulvey, Patrick J.; Nicholson, Starr

    In fall 1999, the 762 degree-granting physics departments in the United States were asked to provide information on their current enrollments and recent degrees, and data were received from 93% of the departments. The number of individuals receiving physics bachelor's degrees was at a 40-year low, with 3,646 degrees conferred in the class of 1999.…

  18. Tech-Prep/Associate Degree Program Guide: Tech Prep Associate Degree Program, Business Administration Associate Degree Program, Office Administration Associate Degree Program, Allied Health Associate Degree Program.

    ERIC Educational Resources Information Center

    Marmaras, Judy; Neri, Pat

    The Tech-Prep Associate Degree Program (TPAD) at the Community College of Rhode Island (CCRI) in Warwick, is a high school/community college partnership providing high school students with an alternative program of study focused on goal setting, basic academic skills development, and the skills needed to pursue a career in a technical, business or…

  19. 7 CFR 29.3101 - Elements of quality and degrees of each element.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... use of words or terms designated as degrees. These several degrees are arranged to show their relative... surface (smoothness) Smooth Even Wavy Wrinkly Rough. 5 Finish Bright Clear Moderate Dull Dingy. 6...

  20. A SOUTHERN ATLAS OF GALACTIC HYDROGEN (THE REGION 0 degrees \\< Q \\< 12 degrees, -3 degrees >/ B -17 degrees)

    NASA Astrophysics Data System (ADS)

    Franco, M. L.; Poppel, W. G. L.; Vieira, E. R.

    1987-05-01

    RESUMEN Se presentan datos observacionales en la lfnea de 21-cm del hidr6geno neutro obtenidos con el radiotelescopio de 30-rn del lAR. Las observaciones cubren la regi6n 00 < Q 120, 30 > b - 170 en intervalos dell0 tanto en Q como en b. El intervalo de velocidades radiales se extiende desde -100 km 1 hasta + 100 km 1 con una resolucj6n cinematica de 2km 1 ABSTRACT We present observational data in the 21-rn line of neutral hydrogen, which have been obtained with the 30-rn dish of the lAR. The observations cover 00 < Q 120, 30 > b > 170 at intervals of 10 in both Qand b. The radial velocity interval extends from -100 to + 100km 1 with a kinematical resolution of 2 km s- . Key words: GALAXY-STRUCTURE - RADIO LINES-21-cm

  1. The Technology of Two Degrees

    SciTech Connect

    Edmonds, James A.; Smith, Steven J.

    2006-09-29

    This paper examines the technology implications of limiting the change in mean global surface temperature (GMST) to two degrees Celsius (2oC) relative to preindustrial temperatures. Understanding the implications of this goal is clouded by uncertainty in key physical science parameters, particularly the climate sensitivity. If the climate sensitivity is 2.5oC then stabilization implies stabilization of CO2 concentrations at less than 500 parts per million (ppm) with a peak in global CO2 emissions occurring in the next 15 years and with a decline in emissions to 3.1 petagrams of carbon per year (PgC/y) by 2095. Under such circumstances the value of technology improvements beyond those assumed in the reference case is found to be exceptionally high, denominated in trillions of 1990 USD. The role of non-CO2 greenhouse gases is important. Aerosols could produce significant feedbacks, though uncertainty is significant. If the climate sensitivity is 4.5oC or greater, it may be impossible to hold GMST change below 2oC. On the other hand if the climate sensitivity is 1.5oC, limiting GMST change to 2oC may be a trivial matter requiring little deviation from a reference emissions path until after the middle of the 21st century.

  2. Doctorate nursing degree in Spain

    PubMed Central

    López-Montesinos, Mª José; Maciá-Soler, Loreto

    2015-01-01

    Analytical and descriptive study of the process of change being experienced in the Spanish university system over the last decade (2005-2014). OBJECTIVE: To describe the structural changes occurring in Nursing Education in Spain, reaching access to doctoral studies from the European Convergence Process and the subsequent legislative development. METHODOLOGY: Bibliographical review of royal decrees and reference literature on the subject of study and descriptive analysis of the situation. RESULTS: Carries various changes suffered in the curricula of nursing education in the last decade, the legislation of the European Higher Education sets the guidelines for current studies of Masters and Doctorates. CONCLUSIONS: The implementation of the Master and Doctorate stages after a basic degree, which is now possible with the new legislation. A formal beginning made of scientific nursing in order to generate their own lines of research led by Doctors of nursing who can integrate in research groups under the same condition as other researcher, yet now, from the nursing discipline itself. PMID:26312628

  3. The Complex Case of Positioning the Foundation Degree: Making Sense of a Degree That Is Not a Degree

    ERIC Educational Resources Information Center

    Kadembo, Ernest

    2008-01-01

    The Foundation degree was launched in 2001 and has enjoyed growth but remains a controversial qualification. Foundation Degree Forward, the body charged by the UK government with providing a "national network or expertise to support the development and validation of high-quality Foundation degrees" is championing the marketing of the…

  4. Are Master's Degrees in Gerontology Comparable?

    ERIC Educational Resources Information Center

    Peterson, David A.

    1984-01-01

    Compares gerontology master's degree curricula for length, content, and requirements. Results showed they have great comparability and fall within established guidelines. Master's degree programs in gerontology appear to be sufficiently similar to allow for beginning discussions of accreditation. (JAC)

  5. Sources and Information on Transfer Associate Degrees

    ERIC Educational Resources Information Center

    Ayon, Carlos

    2012-01-01

    This chapter provides an annotated bibliography of articles about the effects of transfer associate degrees and related statewide transfer and articulation policies. It also provides links to transfer degree legislation in several states.

  6. Oxidation of spent fuel in air at 175{degree} to 195{degree}C

    SciTech Connect

    Einziger, R.E.; Buchanan, H.C.; Thomas, L.E.; Stout, R.B.

    1992-04-01

    Oxidation tests in dry air were conducted on four LWR spent fuels at 175{degrees} and 195{degrees}C to determine the effect of the fuel characteristics on the oxidation state likely to exist at the time leaching occurs in a potential repository. Weight changes were measured and samples were examined by XRD, ceramography, TEM, and TGA. Despite local variations in the grain boundary susceptibility to oxidation, all four fuels progressed toward an apparent endpoint at an oxygen-to-metal (O/M) ratio of 2.4. The sole oxidation product was U{sub 4}O{sub 9+x,} a cubic phase structurally related to UO{sub 2} but with a slightly smaller lattice constant. The growth of the U{sub 4}O{sub 9+x} from the grain boundaries into the UO{sub 2} grains followed parabolic kinetics and had an activation energy of 26.6 kcal/mol. Based on the kinetics, the time required at 95{degrees}C to completely oxidize LWR spent fuel to U{sub 4}O{sub 9+x} would be at least 2000 yr. The next oxidation product to form after the U{sub 4}O{sub 9+x} phase may be U{sub 3}O{sub 8,} but no U{sub 3}O{sub 8} or other dilatational oxidation product has been detected in these accelerated tests conducted up to 25,000 h.

  7. Oxidation of spent fuel in air at 175 degree to 195 degree C

    SciTech Connect

    Einziger, R.E.; Buchanan, H.C.; Thomas, L.E. ); Stout, R.B. )

    1992-04-01

    Oxidation tests in dry air were conducted on four LWR spent fuels at 175{degrees} and 195{degrees}C to determine the effect of the fuel characteristics on the oxidation state likely to exist at the time leaching occurs in a potential repository. Weight changes were measured and samples were examined by XRD, ceramography, TEM, and TGA. Despite local variations in the grain boundary susceptibility to oxidation, all four fuels progressed toward an apparent endpoint at an oxygen-to-metal (O/M) ratio of 2.4. The sole oxidation product was U{sub 4}O{sub 9+x,} a cubic phase structurally related to UO{sub 2} but with a slightly smaller lattice constant. The growth of the U{sub 4}O{sub 9+x} from the grain boundaries into the UO{sub 2} grains followed parabolic kinetics and had an activation energy of 26.6 kcal/mol. Based on the kinetics, the time required at 95{degrees}C to completely oxidize LWR spent fuel to U{sub 4}O{sub 9+x} would be at least 2000 yr. The next oxidation product to form after the U{sub 4}O{sub 9+x} phase may be U{sub 3}O{sub 8,} but no U{sub 3}O{sub 8} or other dilatational oxidation product has been detected in these accelerated tests conducted up to 25,000 h.

  8. Depression, mood state, and back pain during microgravity simulated by bed rest

    NASA Technical Reports Server (NTRS)

    Styf, J. R.; Hutchinson, K.; Carlsson, S. G.; Hargens, A. R.

    2001-01-01

    OBJECTIVE: The objective of this study was to develop a ground-based model for spinal adaptation to microgravity and to study the effects of spinal adaptation on depression, mood state, and pain intensity. METHODS: We investigated back pain, mood state, and depression in six subjects, all of whom were exposed to microgravity, simulated by two forms of bed rest, for 3 days. One form consisted of bed rest with 6 degrees of head-down tilt and balanced traction, and the other consisted of horizontal bed rest. Subjects had a 2-week period of recovery between the studies. The effects of bed rest on pain intensity in the lower back, depression, and mood state were investigated. RESULTS: Subjects experienced significantly more intense lower back pain, lower hemisphere abdominal pain, headache, and leg pain during head-down tilt bed rest. They had higher scores on the Beck Depression Inventory (ie, were more depressed) and significantly lower scores on the activity scale of the Bond-Lader questionnaire. CONCLUSIONS: Bed rest with 6 degrees of head-down tilt may be a better experimental model than horizontal bed rest for inducing the pain and psychosomatic reactions experienced in microgravity. Head-down tilt with balanced traction may be a useful method to induce low back pain, mood changes, and altered self-rated activity level in bed rest studies.

  9. 45 CFR 2400.41 - Degree programs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... degree in history or political science (including government or politics), the degree of Master of Arts in Teaching in history or political science (including government or politics), or a related master's degree in education that permits a concentration in American history, American government, social...

  10. Profile of the Nontraditional Doctoral Degree Student

    ERIC Educational Resources Information Center

    Offerman, Michael

    2011-01-01

    What type of individual pursues a nontraditional doctoral degree? Although answering this question is the main purpose of this chapter, there is an underlying story that provides context for how and why these individuals came to pursue a doctoral degree. The tremendous growth in the number of doctoral students and doctoral degree-granting…

  11. The Master's Degree: Jack of All Trades.

    ERIC Educational Resources Information Center

    Green, Joslyn L., Ed.

    The master's degree is discussed in seven papers written by academic officers serving state coordinating and governing boards. In "Toward a New Paradigm," Judith S. Glazer considers changes in the master's degree and suggests that the degree is changing to meet student needs, the job market, and external standards. Martine F. Hammond's…

  12. First Professional Degree Awards to Women.

    ERIC Educational Resources Information Center

    Brown, George H.

    Changes in the percentage representation of women among recipients of first professional degrees are examined between the academic years 1970-71 and 1975-76. The data were collected through the annual Survey of Degrees and Other Formal Awards Conferred. A first professional degree is one that "signifies completion of the academic requirements for…

  13. Physics Bachelors with Master's Degrees. AIP Report.

    ERIC Educational Resources Information Center

    Ivie, Rachel; Stowe, Katie

    This report provides information about holders of bachelor's degrees in physics who went on to earn master's degrees and were employed at the time of the survey (completed by spring 1999). This is the second report based on data collected from people who earned bachelor's degrees between 1990 and 1993, but it is the first time the American…

  14. Enrollments and Degrees Report. AIP Report.

    ERIC Educational Resources Information Center

    Mulvey, Patrick J.; Nicholson, Starr

    This report presents the results of a fall 1999 survey of U.S. colleges and universities that offer doctoral, master's, and bachelor's degrees in physics and astronomy, focusing on degree production and current student enrollment. Highlighted are the following: (1) after four years of significant declines, physics bachelor's degrees conferred in…

  15. Enrollments and Degrees Report. AIP Report.

    ERIC Educational Resources Information Center

    Mulvey, Patrick J.; Nicholson, Starr

    In fall 2000, the 770 degree-granting physics departments in the United States were asked to provide information on their current enrollments and recent degrees granted, and responses were received from 98% of the departments. Findings show that the number of individuals receiving physics bachelors degrees increased substantially after a decade of…

  16. Report on Time-Shortened Degree Program.

    ERIC Educational Resources Information Center

    Magill, Samuel H.

    Since January 1971, a number of colleges and universities have announced time-shortened degree programs. In the interest of examining and clarifying the various approaches to and understanding of time-shortened degrees, this brief analysis is offered. There appear to be 4 approaches to the reduction of time spent on the way to the B.A. degree, one…

  17. 45 CFR 2400.41 - Degree programs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... degree in history or political science (including government or politics), the degree of Master of Arts in Teaching in history or political science (including government or politics), or a related master's..., or political science. Graduate degrees under which study is excluded from fellowship support...

  18. 45 CFR 2400.41 - Degree programs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... degree in history or political science (including government or politics), the degree of Master of Arts in Teaching in history or political science (including government or politics), or a related master's..., or political science. Graduate degrees under which study is excluded from fellowship support...

  19. 45 CFR 2400.41 - Degree programs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... degree in history or political science (including government or politics), the degree of Master of Arts in Teaching in history or political science (including government or politics), or a related master's..., or political science. Graduate degrees under which study is excluded from fellowship support...

  20. 45 CFR 2400.41 - Degree programs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... degree in history or political science (including government or politics), the degree of Master of Arts in Teaching in history or political science (including government or politics), or a related master's..., or political science. Graduate degrees under which study is excluded from fellowship support...

  1. Dual degree partnership in nursing: an innovative undergraduate educational model.

    PubMed

    Bastable, Susan B; Markowitz, Marianne

    2012-10-01

    We report the success of a unique articulation Dual Degree Partnership in Nursing (DDPN) model. The process used to establish and implement this approach is described. Unlike typical 2+2 agreements between associate degree (AD) and bachelor degree (BS) nursing education programs, the DDPN is designed with a 1+2+1 sequence. Intended to attract high school students, this model provides the opportunity to earn two degrees (AD and BS) while experiencing a 4-year campus living and learning environment. This configuration was accomplished without compromising the integrity of either of the established programs. After collecting data over the past 6 years, this model demonstrates popularity with the traditional-aged student, as well as success from an academic perspective. Statistics on retention, graduation, and NCLEX® pass rates indicate the feasibility and success of the model. Based on the findings, the potential for replication is promising for other colleges interested in a similar collaboration.

  2. Degrees Conferred by Connecticut Institutions of Higher Education Highlights, 2007-08. Report

    ERIC Educational Resources Information Center

    Connecticut Department of Higher Education (NJ1), 2009

    2009-01-01

    This paper presents the degrees conferred by Connecticut institutions of higher education in 2007-08. Connecticut colleges and universities awarded 36,634 degrees in 2007-08 (up 1.6% over 2006-07), the state's seventh consecutive year of growth and a 28 percent increase since 1998. Once again, the top five degree-producing disciplines were…

  3. Hardness recovery of 85% cold-worked V-Ti and V-Cr-Ti alloys upon annealing at 180{degrees}C to 1200{degrees}C

    SciTech Connect

    Loomis, B.A.; Nowicki, L.J.; Smith, D.L.

    1995-04-01

    The objective of this research is to determine the effect of heat treatment of cold-worked V-Ti and V-Cr-Ti alloys on their resulting microstructures and to correlate the results with the physical and mechanical properties of these alloys. Annealing of 85% cold-worked unalloyed V and V-(1-18)Ti alloys for 1 hr at 180 to 1200{degree}C results in hardness maxima at 180-250{degree}C, 420-600{degree}C, and 1050-1200{degree}C and in hardness minima at 280-360{degree}C and, depending on Ti concentration in the alloy, at 840-1050{degree}C. Annealing of 85% cold-worked V-(4-15)Cr-(3-6)Ti alloys for 1 hr at 180{degree}C to 1200{degree}C results in harness maxima at 180-250{degree}C, 420-800{degree}C, and 1050-1200{degree}C, and in hardness minima at 280-360{degree}C and 920-1050{degree}C.

  4. Selected Bibliography on Associate Degree Programs in Nursing.

    ERIC Educational Resources Information Center

    National League for Nursing, New York, NY. Dept. of Associate Degree Programs.

    This annotated bibliography consists of 99 entries, primarily journal articles, most of which were published after 1966. Organization is under the following headings: (1) Associate Degree Nursing (ADN) Programs--What They Are, (2) Planning for ADN Program, (3) Move to Educational Institutions, (4) Administration, (5) Faculty, (6) Teaching Methods,…

  5. Predicting Bachelor's Degree Attainment for Developmental Math Students

    ERIC Educational Resources Information Center

    Burley, Hansel; Butner, Bonita; Anderson, Connie Wilson; Siwatu, Kamau Oginga

    2009-01-01

    This study used the National Educational Longitudinal Study: 88 /2000 (NELS 88: /2000) dataset to explore characteristics associated with college degree attainment. The study was informed by Ajzen's Theory of Planned Behavior. The sample size was 6,832 postsecondary students. The findings revealed that developmental math students were less…

  6. Motivations of Adults Enrolling in an Evening Graduate Degree Program

    ERIC Educational Resources Information Center

    Frazier, Bradford R.

    2009-01-01

    According to the American Council on Education (2006), it is estimated that more than 41% of students enrolled in degree granting programs in higher education are nontraditional, adult students age 22 or older. Many of these 6 million students are entering graduate school as working adults. According to previous research on non-traditional…

  7. Cooperation in an evolutionary prisoner's dilemma on networks with degree-degree correlations.

    PubMed

    Devlin, Stephen; Treloar, Thomas

    2009-08-01

    We study the effects of degree-degree correlations on the success of cooperation in an evolutionary prisoner's dilemma played on a random network. When degree-degree correlations are not present, the standardized variance of the network's degree distribution has been shown to be an accurate analytical measure of network heterogeneity that can be used to predict the success of cooperation. In this paper, we use a local-mechanism interpretation of standardized variance to give a generalization to graphs with degree-degree correlations. Two distinct mechanisms are shown to influence cooperation levels on these types of networks. The first is an intrinsic measurement of base-line heterogeneity coming from the network's degree distribution. The second is the increase in heterogeneity coming from the degree-degree correlations present in the network. A strong linear relationship is found between these two parameters and the average cooperation level in an evolutionary prisoner's dilemma on a network.

  8. Assessment of Aliasing Errors in Low-Degree Coefficients Inferred from GPS Data.

    PubMed

    Wei, Na; Fang, Rongxin

    2016-05-11

    With sparse and uneven site distribution, Global Positioning System (GPS) data is just barely able to infer low-degree coefficients in the surface mass field. The unresolved higher-degree coefficients turn out to introduce aliasing errors into the estimates of low-degree coefficients. To reduce the aliasing errors, the optimal truncation degree should be employed. Using surface displacements simulated from loading models, we theoretically prove that the optimal truncation degree should be degree 6-7 for a GPS inversion and degree 20 for combing GPS and Ocean Bottom Pressure (OBP) with no additional regularization. The optimal truncation degree should be decreased to degree 4-5 for real GPS data. Additionally, we prove that a Scaled Sensitivity Matrix (SSM) approach can be used to quantify the aliasing errors due to any one or any combination of unresolved higher degrees, which is beneficial to identify the major error source from among all the unresolved higher degrees. Results show that the unresolved higher degrees lower than degree 20 are the major error source for global inversion. We also theoretically prove that the SSM approach can be used to mitigate the aliasing errors in a GPS inversion, if the neglected higher degrees are well known from other sources.

  9. Assessment of Aliasing Errors in Low-Degree Coefficients Inferred from GPS Data

    PubMed Central

    Wei, Na; Fang, Rongxin

    2016-01-01

    With sparse and uneven site distribution, Global Positioning System (GPS) data is just barely able to infer low-degree coefficients in the surface mass field. The unresolved higher-degree coefficients turn out to introduce aliasing errors into the estimates of low-degree coefficients. To reduce the aliasing errors, the optimal truncation degree should be employed. Using surface displacements simulated from loading models, we theoretically prove that the optimal truncation degree should be degree 6–7 for a GPS inversion and degree 20 for combing GPS and Ocean Bottom Pressure (OBP) with no additional regularization. The optimal truncation degree should be decreased to degree 4–5 for real GPS data. Additionally, we prove that a Scaled Sensitivity Matrix (SSM) approach can be used to quantify the aliasing errors due to any one or any combination of unresolved higher degrees, which is beneficial to identify the major error source from among all the unresolved higher degrees. Results show that the unresolved higher degrees lower than degree 20 are the major error source for global inversion. We also theoretically prove that the SSM approach can be used to mitigate the aliasing errors in a GPS inversion, if the neglected higher degrees are well known from other sources. PMID:27187392

  10. Degrees and Certificates Awarded, 2001-2002.

    ERIC Educational Resources Information Center

    Coperthwaite, Corby A.; Jones, Dennis

    This document reports on degrees and certificates awarded by the Connecticut community colleges during the 2001-02 academic year, using a set of eight categories. The colleges awarded 3,977 degrees and certificates in 2001-02. This represents a 1.3% increase over the previous year, and a 7.2% decrease since 1998. The colleges awarded 735…

  11. Engineering and Engineering Technology Degrees, 1990.

    ERIC Educational Resources Information Center

    Ellis, R. A.

    1991-01-01

    The number of B.S., M.S./P.E., and Ph.D. degrees in engineering and engineering technology awarded by U.S. colleges and universities is tabulated according to the following criteria: by state, by school, curriculum, type of recipient, and by school and degree level. (KR)

  12. New High in Engineering Degree Production. Facts

    ERIC Educational Resources Information Center

    Connecticut Department of Higher Education (NJ1), 2010

    2010-01-01

    Several of the state's key industry sectors depend heavily on employees with advanced scientific, analytic and technical knowledge. Among the fields closely related to these sectors, engineering degrees have posted the largest gain. This paper presents details on the following facts: (1) 2009 represented a record high for engineering degrees; (2)…

  13. Experiencing Higher Degree Research Supervision as Teaching

    ERIC Educational Resources Information Center

    Bruce, Christine; Stoodley, Ian

    2013-01-01

    This article describes higher degree research supervisors' experiences of supervision as teaching. While research education is considered central to the higher degree research experience, comparatively little is known to date of the teaching lenses adopted by supervisors as they go about their supervision. We worked with 35 supervisors engaged in…

  14. An Innovative Baccalaureate Degree: Applied versus Traditional

    ERIC Educational Resources Information Center

    Arney, Janna B.; Hardebeck, Suzanne; Estrada, Joselito; Permenter, Vivian

    2006-01-01

    The bachelor of applied arts and sciences (BAAS) degree is a baccalaureate program designed to meet the needs of nontraditional students by allowing technical hours to be transferred for credit to a baccalaureate degree. To determine if the university was positively serving the needs of its constituents, salaries of BAAS graduates were compared to…

  15. Nuclear Engineering Enrollments and Degrees, 1982.

    ERIC Educational Resources Information Center

    Sweeney, Deborah H.; And Others

    This report presents data on the number of students enrolled and the number of bachelor's, master's, and doctoral degrees awarded in academic year 1981-82 from 72 United States institutions offering degree programs in nuclear engineering or nuclear options within other engineering fields. Presented as well are historical data for the last decade…

  16. Master's Degree Studies: Expectations versus Reality

    ERIC Educational Resources Information Center

    Swanepoel, C. H.

    2010-01-01

    During the past two decades, higher education in South Africa has been affected drastically by transformation. An issue that has specifically been influenced is master's degrees. A significant increase in the demand for access to course work master's degrees has been experienced, while universities themselves have been confronted with a new…

  17. Practitioner-Focused Degrees in Politics

    ERIC Educational Resources Information Center

    Craig, John

    2010-01-01

    This article aims to explore practitioner-focused degrees in politics. It begins by defining the term and outlining the key features in comparison to other politics degrees. The underlying pedagogical principles that inform the design of teaching, learning, and assessment are then explored, before the article moves on to discuss the development of…

  18. Effect of Dissolved Oxygen on the Filterability of Jet Fuels for Temperatures Between 300 Degrees and 400 Degrees F

    NASA Technical Reports Server (NTRS)

    Mckeown, Anderson B; Hibbard, Robert R

    1955-01-01

    The effect of dissolved oxygen in the filter-clogging characteristics of three JP-4 and two JP-5 fuels was studied at 300 degrees to 400 degrees F in a bench- scale rig, employing filter paper as the filter medium. The residence time of the fuel at the high temperature was approximately 6 seconds. For these conditions, the clogging characteristics of the fuels increased with both increasing temperature and increasing concentration of dissolved oxygen. The amount of insoluble material formed at high temperatures necessary to produce clogging of filters was very small, of the order of 1 milligram per gallon of fuel.

  19. Virtual displays for 360-degree video

    NASA Astrophysics Data System (ADS)

    Gilbert, Stephen; Boonsuk, Wutthigrai; Kelly, Jonathan W.

    2012-03-01

    In this paper we describe a novel approach for comparing users' spatial cognition when using different depictions of 360- degree video on a traditional 2D display. By using virtual cameras within a game engine and texture mapping of these camera feeds to an arbitrary shape, we were able to offer users a 360-degree interface composed of four 90-degree views, two 180-degree views, or one 360-degree view of the same interactive environment. An example experiment is described using these interfaces. This technique for creating alternative displays of wide-angle video facilitates the exploration of how compressed or fish-eye distortions affect spatial perception of the environment and can benefit the creation of interfaces for surveillance and remote system teleoperation.

  20. Synthesis of branched polysaccharides with tunable degree of branching.

    PubMed

    Ciric, Jelena; Loos, Katja

    2013-03-01

    An in vitro enzyme-catalyzed tandem reaction using the enzymes phosphorylase b from rabbit muscle and Deinococcus geothermalis glycogen branching enzyme (Dg GBE) to obtain branched polyglucans with tunable degree of branching (2% ÷ 13%) is presented. The tunable degree of branching is obtained by varying the reaction conditions such as pH value, the choice of reducing agent and its concentration and reaction time. Linear amylose is formed by the phosphorylase-catalyzed propagation of glucose-1-phosphate while Dg GBE introduces branching points on the α-(1→6) position by relocating short oligosaccharide chains. Our results show that the best way to obtain different degrees of branching with this set of enzymes is by regulation of the reaction time.

  1. Recent bed rest results and countermeasure development at NASA

    NASA Technical Reports Server (NTRS)

    Hargens, A. R.

    1994-01-01

    Bedrest studies of normal subjects provide opportunities to understand physiologic responses to supine posture and inactivity. Furthermore, head-down tilt has been a valuable procedure to investigate adaptation to microgravity and development of countermeasures to maintain the health and well-being of humans during space-flight. Recent bedrest experiments at NASA have ranged in duration from a few hours to 17 weeks. Acute studies of 6 degrees head-down tilt indicate that elevation of capillary blood pressure from 28 to 34 mm Hg and increased capillary perfusion in tissues of the head cause facial and intracranial edema. Intracranial pressure increases from 2 to 17 mm Hg going from upright posture to 6 degrees head-down tilt. Microvessels of the head have a low capacity to constrict and diminish local perfusion. Elevation of blood and tissue fluid pressures/flow in the head may also explain the higher headward bone density associated with long-term head-down tilt. These mechanistic studies of head-down tilt, along with a better understanding of the relative stresses involved with upright posture and lower body negative pressure, have facilitated development of suitable physiologic countermeasures to maintain astronaut health during microgravity. Presently no exercise hardware is available to provide a blood pressure gradient from head to feet in space. However, recent studies in our laboratory suggest that treadmill exercise using a graded lower-body compression suit and 100 mmHg lower body negative pressure provides equivalent or greater physiologic stress than similar upright exercise on Earth. Therefore, exercise within a lower body negative pressure chamber may provide a cost-effective and simple countermeasure to maintain the cardiovascular and neuro-musculoskeletal systems of astronauts during long-duration flight.

  2. Differences in STEM degree attainment by region, ethnicity, and degree type

    NASA Astrophysics Data System (ADS)

    Koledoye, Kimberly A.

    Purpose One purpose of this study was to determine the extent to which a difference was present in the STEM degree attainment of all students and particularly of URMs between the 2001 and the 2009 academic year. The second purpose of this study was to determine the extent to which a difference was present in the attainment of STEM associate degrees and bachelor degrees of all students and particularly of URMs awarded between the 2001 and the 2009 academic year. Another purpose of this study was to determine the extent to which a difference existed in STEM associate degree and STEM bachelor degree attainment among geographic regions between the 2001 and the 2009 academic years. The extent to which a difference existed in the STEM bachelor degree and associate degree attainment of URMs among geographic regions between the 2001 to the 2009 academic year was ascertained. The final purpose of this study was to determine the extent to which a difference was present in STEM associate degree and bachelor degree attainment of all students and particularly URMs as a function of degree type between the 2001 academic year and the 2009 academic year. Methodology Archival data from the Integrated Postsecondary Education Data System were utilized to compare STEM degree attainment for regions, regions for URMs, STEM degree attainment overall and for URMs, STEM degree attainment classified by associate degrees and bachelor degrees for all students and URMs, and STEM degree attainment of associate degrees and bachelor degrees for all students and URMs by specific degree type between 2001 and 2009. Findings In this non-experimental causal comparative investigation, statistically significant differences were revealed in 95 of the 165 comparisons. Declining associate degree attainment was concerning, particularly in the computer and information sciences and engineering and engineering technologies. Moderate increases were determined in bachelor degree attainment with statistically

  3. Correct degree distribution of apollonian networks

    NASA Astrophysics Data System (ADS)

    Guo, Jin-Li; Wang, Li-Na

    2010-08-01

    In this paper, we point out that there is a shortcoming of the degree distribution and the analyzing approach of the Apollonian network in [Andrade J S, Herrmann H J, Andrade R F S, et al. Phys. Rev. Lett. 94, 018702 (2005).]. Because the Apollonian network is a deterministic network, its degree distribution can be directly calculated. We correct the degree distribution of the Apollonian network. We also give a numerical simulation of network evolution. The analytical result agrees with the simulation well. The results show that there is the shortcoming of the results of Herrmann et al.

  4. Lens positioner with five degrees of freedom

    DOEpatents

    Kobierecki, Marian W.; Rienecker, Jr., Frederick

    1978-01-01

    A device for positioning lenses precisely with five degrees of freedom (three translations and two angular rotations). The unique features of the device are its compact design, large clear aperture, and high degree of positioning accuracy combined with five degrees of freedom in axis motion. Thus, the device provides precision and flexibility in positioning of optical components. BACKGROUND OF THE INVENTION The invention described herein was made in the course of, or under, Contract No. AT(29-1)-1183, with the United States Energy Research and Development Administration.

  5. Branding the bio/biomedical engineering degree.

    PubMed

    Voigt, Herbert F

    2011-01-01

    The future challenges to medical and biological engineering, sometimes referred to as biomedical engineering or simply bioengineering, are many. Some of these are identifiable now and others will emerge from time to time as new technologies are introduced and harnessed. There is a fundamental issue regarding "Branding the bio/biomedical engineering degree" that requires a common understanding of what is meant by a B.S. degree in Biomedical Engineering, Bioengineering, or Biological Engineering. In this paper we address some of the issues involved in branding the Bio/Biomedical Engineering degree, with the aim of clarifying the Bio/Biomedical Engineering brand.

  6. Radiation protection enrollments and degrees, 1981

    SciTech Connect

    Little, J R; Shirley, D L; Blair, L M

    1982-05-01

    This report presents data on the number of students enrolled and the degrees awarded in academic year 1980-81 from 61 U.S. universities offering degree programs in radiation protection or related areas that would enable students to work in the health physics field. The report includes historical survey data for the last decade and provides information such as trends by degree level, foreign national student participation, female and minority student participation, and placement of graduates. Also included is a listing of the universities by type of program and number of students.

  7. Second-Degree Learners in Associate Degree Nursing Programs: Characteristics and Progression Success

    ERIC Educational Resources Information Center

    McGinley, Patricia M.

    2013-01-01

    Second degree learners are attending associate (ADN), accelerated baccalaureate (BSN), and entry level masters (ELM) degree nursing programs. There is limited data related to the socio-demographic characteristics and graduation success rates of students attending accelerated BSN or ELM programs and no data related to second-degree learners…

  8. Time to Advanced Degree: A Profile of Recent Advanced Degree Recipients.

    ERIC Educational Resources Information Center

    de Wolf, Virginia A.; Eeckhoudt, Jeannette

    All students receiving master's degrees, doctoral candidacy status, and doctorates at the University of Washington between fall 1974 and the summer quarter 1975 were studied. Data are reported for male, female, and total groups on source of bachelor's degree, age at entry, number of years since receipt of the most recent degree, credits earned,…

  9. Enhancing the Transition from a Foundation Degree to the Third Year of an Undergraduate Degree

    ERIC Educational Resources Information Center

    Mytton, Graham; Rumbold, Penny

    2011-01-01

    One-day transition to university workshops have been successful in enhancing peer networks. This study aimed to influence the transition from a Foundation Degree to a third year Undergraduate Degree programme through the use of peer led workshops. Two 2-hour workshops were planned and delivered by five previous students of the Foundation Degree,…

  10. Characteristics of Associate's Degree Attainers and Time to Associate's Degree. Web Tables. NCES 2012-271

    ERIC Educational Resources Information Center

    Green, Caitlin; Radwin, David

    2012-01-01

    The number of associate's degrees conferred by U.S. postsecondary institutions increased 30 percent from 1997 to 2007, from 571,000 to 745,000, and is projected to grow another 30 percent by 2020, a faster pace than the actual and projected growth in bachelor's degrees awarded. Despite the growing prevalence of associate's degrees, however, there…

  11. The Doctor of Physical Therapy Degree: A New Curriculum for a New Degree

    ERIC Educational Resources Information Center

    Rapport, Mary Jane K.; Stelzner, Denise; Rodriguez, Jenny

    2007-01-01

    By 2020, all graduates of accredited physical therapy programs will receive the Doctor of Physical Therapy (DPT) degree. Bachelor degrees in physical therapy are no longer granted, and over 83% (N = 176 accredited programs) of the entry-level physical therapy education programs already grant the DPT degree. The purpose of this article is to…

  12. Building Experiential Learning into External Degree Programs.

    ERIC Educational Resources Information Center

    Keeton, Morris T.

    1979-01-01

    The need to build experiential learning into external degree programs is examined in terms of the framework identifying the functions of experiential elements of a program. Successful forms are defined and models of these are described. (JMF)

  13. Massachusetts General Hospital starts own degree programs.

    PubMed

    1979-01-01

    Massachusetts General Hospital has established a new Education Division that administers various degree programs in seven professional fields. Major emphasis is on interdisciplinary study and integration of the academic and the clinical components of training.

  14. Common Degree Program for Industrial Education Teachers

    ERIC Educational Resources Information Center

    Matthews, John I.

    1974-01-01

    A consortium approach in Delaware's State technical schools offers a common B. S. degree competency-based program to persons seeking a teaching career in either trade and industry or industrial arts. (Author/AJ)

  15. Biomedical engineering degrees at Lyon 1 University.

    PubMed

    Perrin, E; Berger-Vachon, C; Ray, C; Canet-Soulas, E; Hartmann, D; Oudin-Dardun, F; Briguet, A

    2007-01-01

    Biomedical diploma degrees have a long tradition at Lyon 1, Claude Bernard University. Since 2004, the transition towards the LMD system leaded to a unified Bachelor and Master Degree in Biomedical Engineering. A next evolution plans the creation of a Biomedical Engineering Department in the future Polytechnic School of Claude Bernard University. This department will form professionals in Biomedical Engineering, Medical Physics and for academic employment in Universities and research structures.

  16. Interplay of degree correlations and cluster synchronization

    NASA Astrophysics Data System (ADS)

    Jalan, Sarika; Kumar, Anil; Zaikin, Alexey; Kurths, Jürgen

    2016-12-01

    We study the evolution of coupled chaotic dynamics on networks and investigate the role of degree-degree correlation in the networks' cluster synchronizability. We find that an increase in the disassortativity can lead to an increase or a decrease in the cluster synchronizability depending on the degree distribution and average connectivity of the network. Networks with heterogeneous degree distribution exhibit significant changes in cluster synchronizability as well as in the phenomena behind cluster synchronization as compared to those of homogeneous networks. Interestingly, cluster synchronizability of a network may be very different from global synchronizability due to the presence of the driven phenomenon behind the cluster formation. Furthermore, we show how degeneracy at the zero eigenvalues provides an understanding of the occurrence of the driven phenomenon behind the synchronization in disassortative networks. The results demonstrate the importance of degree-degree correlations in determining cluster synchronization behavior of complex networks and hence have potential applications in understanding and predicting dynamical behavior of complex systems ranging from brain to social systems.

  17. Comparison of 45-degree Kelman and 45-degree balanced phaco tip designs in torsional microcoaxial phacoemulsification

    PubMed Central

    Demircan, Süleyman; Ataş, Mustafa; Göktaş, Emre; Başkan, Burhan

    2015-01-01

    AIM To compare the intraoperative performance and postoperative outcome after microcoaxial torsional phacoemulsification using either a Kelman or balanced phaco tip. METHODS Cataracts were treated using 2.2 mm microcoaxial torsional phacoemulsification using either a 45-degree mini-flared Kelman® or a 45-degree Intrepid® Balanced phaco tip. Intraoperative measurements included total ultrasound (US) time, cumulative dissipated energy (CDE), torsional US time, and balanced salt solution (BSS) use. The central endothelial cell density (ECD) and central corneal thickness (CCT) were evaluated preoperatively and postoperatively 1, 7, and 30d after surgery using noncontact specular microscopy. RESULTS The 116 enrolled eyes (116 patients) were divided equally between the Kelman and balanced tip groups. Intraoperative measurements showed significantly less total US time, torsional US time, CDE, and BSS use in the balanced group than in Kelman group (P<0.05). The total US time, torsional US time, CDE, and BSS use were 17.45±14.53s, 16.63±13.97s, 6.38±5.26, and 48.21±17.21 mL in the Kelman group and 11.39 ± 9.60s, 10.90 ± 9.25s, 4.04 ± 3.42, and 41.36 ± 12.70 mL in the balanced group, respectively. CONCLUSION Torsional phacoemulsification performed with a balanced tip provided more effective lens removal with less total US time, torsional time, CDE, and BSS use, as well as similar changes in ECD with a Kelman tip in all cataract grades. This special designed phaco tip for torsional phacoemulsification provides an alternative phaco tip for many surgeons' preference with straight phaco tip. PMID:26682167

  18. Pneumatization degree of the anterior clinoid process: a new classification.

    PubMed

    Abuzayed, Bashar; Tanriover, Necmettin; Biceroglu, Huseyin; Yuksel, Odhan; Tanriover, Ozlem; Albayram, Sait; Akar, Ziya

    2010-07-01

    The objective of this study is to determine the incidence and degree of anterior clinoid process pneumatization, in addition highlighting to their clinical significance. Multidetector-row CT scans of the skull base were reviewed in 648 subjects between 2007 and 2008. The presence of pneumatized anterior clinoid process and its degree were studied and documented. These data were statistically analyzed. Pneumatization of the ACP was found in 62 of 648 patients (9.6%) including 32 (51.6%) men and 30 (48.4%) women. The age of these patients ranged from 21 to 82 years (mean, 41 +/- 15.7 years). Pneumatization of the ACP occurred only on the left side in 14 cases (22.6%), only on the right side in 11 cases (17.7%), and bilaterally in 37 patients (59.7%). ACP pneumatization Type I, in which less than 50% of the ACP is pneumatized, was found in 47 of 124 sides (38%), Type II, in which more than 50% but not totally pneumatized ACP, was found in 28 of 124 sides (22.6%), and Type III, in which the ACP is totally pneumatized, was found in 22 of 124 sides (17.7%). The incidence of Type I in the general population was 6.6%, Type II was 3.5%, and Type III was 2.5%. Radiologically recognizing the degree of ACP pneumatization is important in decreasing the incidence of surgical complications during anterior clinoidectomy. Proper intraoperative management can be undertaken with special attention to the new classification.

  19. Laboratory estimation of degree-day developmental requirements of Phlebotomus papatasi (Diptera: Psychodidae).

    PubMed

    Kasap, Ozge Erisoz; Alten, Bulent

    2005-12-01

    Cutaneous leishmaniasis is one of the most important vector-borne endemic diseases in Turkey. The main objective of this study was to evaluate the influence of temperature on the developmental rates of one important vector of leishmaniasis, Phlebotomus papatasi (Scopoli, 1786) (Diptera: Psychodidae). Eggs from laboratory-reared colonies of Phlebotomus papatasi were exposed to six constant temperature regimes from 15 to 32 degrees C with a daylength of 14 h and relative humidity of 65-75%. No adult emergence was observed at 15 degrees C. Complete egg to adult development ranged from 27.89 +/- 1.88 days at 32 degrees C to 246.43 +/- 13.83 days at 18 degrees C. The developmental zero values were estimated to vary from 11.6 degrees C to 20.25 degrees C depending on life stages, and egg to adult development required 440.55 DD above 20.25 degrees C.

  20. Cooling of tropical Brazil (5{degrees}C) during the last glacial maximum

    SciTech Connect

    Stute, M.; Forster, M.; Frischkom, H.

    1995-07-21

    A 30,000-year paleotemperature record derived from noble gases dissolved in carbon-14-dated ground water indicates that the climate in lowland Brazil (Piaui Province, 7{degrees}S, 41.5{degrees}W; altitude, 400 meters) was 5.4{degrees} {+-} 0.6{degrees}C cooler during the last glacial maximum than today. This result suggests a rather uniform cooling of the Americas between 40{degrees}S and 40{degrees}N. A 5.4{degrees}C cooling of tropical South America is consistent with pollen records, snow line reconstructions, and strontium/calcium ratios and {delta}{sup 18}O coral records but is inconsistent with the sea-surface temperature reconstruction of CLIMAP (Climate: Long-Range investigation, Mapping and Prediction). On the basis of these results, it appears that the tropical Americas are characterized by a temperature sensitivity comparable to that found in higher latitudes. 36 refs., 4 figs., 2 tabs.

  1. Introduction of Branching Degrees of Octane Isomers.

    PubMed

    Perdih, Anton

    2016-01-01

    The concept of branching degrees is introduced. In the case of octane isomers it is derived from the values of a set of their physicochemical properties, calculating for each isomer the average of the normalized values and these averages are defined as branching degrees of octane isomers. The sequence of these branching degrees of octane isomers does not differ much from the »regular« one defined earlier. 2,2-Dimethylhexane appears to be less branched than 3,4-dimethylhexane and 3-ethyl, 2-methylpentane, whereas 2,3,4-trimethylpentane appears to be less branched than 3-ethyl, 3-methylpentane. While the increasing number of branches gives rise to increasing branching degrees, the peripheral position of branches and the separation between branches decreases the value of the branching degree. The central position of branches increases it. A bigger branch increases it more than a smaller one. The quantification of these structural features and their correlations with few indices is given as well.

  2. Why do different people choose different university degrees? Motivation and the choice of degree

    PubMed Central

    Skatova, Anya; Ferguson, Eamonn

    2014-01-01

    Different people choose undergraduate degrees to study at university for different reasons. To date, there have been limited attempts to identify individual differences in motivation that drive undergraduate degree choice. We identified that people choose university degrees for four reasons: career concerns (Career), intrinsic interest in the subject (Interest), an opportunity to help others (Helping) and because they are looking for an easy option to get into higher education (Loafing). We investigated whether these motivations apply to the choice of undergraduate degree in two samples: (1) undergraduate (N = 989) and (2) prospective (N = 896) students. We developed the Motivations Influencing Course Choice (MICC) questionnaire to measure these motivations. Scales of Helping, Career, Loafing, and Interest showed good psychometric properties, showed validity with respect to general life goals and personality traits, and predicted actual and prospective degree choices. We demonstrated that medical degrees were chosen due to a mixture of Helping and Career, while engineering degrees were associated with Career and low Interest in the degree. The choice of arts and humanities degrees was driven by Interest and low concern about future career, accompanied with high Loafing. We also demonstrated gender differences: females were high in Helping (both samples) and Interest (only in the undergraduate sample) motivation, while males scored higher in Career (only in the undergraduate sample) and Loafing (both samples). The findings can feed into both theoretical accounts of proximal motivation as well as provide help to improve degree programmes at universities and support better career advice. PMID:25431561

  3. Node degree distribution in spanning trees

    NASA Astrophysics Data System (ADS)

    Pozrikidis, C.

    2016-03-01

    A method is presented for computing the number of spanning trees involving one link or a specified group of links, and excluding another link or a specified group of links, in a network described by a simple graph in terms of derivatives of the spanning-tree generating function defined with respect to the eigenvalues of the Kirchhoff (weighted Laplacian) matrix. The method is applied to deduce the node degree distribution in a complete or randomized set of spanning trees of an arbitrary network. An important feature of the proposed method is that the explicit construction of spanning trees is not required. It is shown that the node degree distribution in the spanning trees of the complete network is described by the binomial distribution. Numerical results are presented for the node degree distribution in square, triangular, and honeycomb lattices.

  4. Human cardiovascular response to sympathomimetic agents during head-down bed rest: the effect of dietary sodium

    NASA Technical Reports Server (NTRS)

    Williams, W. J.; Stuart, C. A.; Fortney, S. M.; Pietrzyk, R. A.; Chen, Y. M.; Whitson, P. A.

    1994-01-01

    Changes in sympathoadrenal function and cardiovascular deconditioning have long been recognized as a feature of the physiological adaptation to microgravity. The deconditioning process, coupled with altered hydration status, is thought to significantly contribute to orthostatic intolerance upon return to Earth gravity. The cardiovascular response to stimulation by sympathomimetic agents before, during, and after exposure to simulated microgravity was determined in healthy volunteers equilibrated on normal or high sodium diets in order to further the understanding of the deconditioning process.

  5. Gender-related Changes in Dorsal Hand and Foot Vein Function Following 60 Days of Head Down Bed Rest

    NASA Technical Reports Server (NTRS)

    Westby, Christian M.; Phillips, Tiffany; Stenger, Michael B.; Platts, Steven H.

    2009-01-01

    It is well known that female astronauts are more likely to experience post-flight orthostatic hypotension and presyncope compared to male astronauts. It has been suggested that the disproportionally higher incidence of presyncope (83% of female vs. 20% male crewmembers) may be due to sex-related differences in vascular function between the upper and lower limbs. However, much of this evidence is specific to changes in resistance vessels. Given that more than 70% of the circulating blood volume resides in compliance vessels, it is conceivable that even small changes in venous function may contribute to post-flight orthostatic hypotension. In spite of this, little is currently known regarding the influence of microgravity exposure on venous function between males and females. PURPOSE: To determine the influence of 60 days of HDBR on dorsal foot and hand vein function between healthy males (M) and females (F). METHODS: Using 2-D ultrasound, dorsal hand and foot vein diameter responses to intravenous infusions phenylephrine (PE), acetylcholine (ACh), and nitroglycerine (NTG) were determined in 26 adults; 10 females (age:37 +/- 2 yr ) and 16 males (age:34 +/- 2 yr ). Changes in venous function were calculated as the difference between diameter at baseline and following each venoactive drug. Differences in venous function between limb and sexes across HDBR were determined using mixed-effects linear regression. RESULTS: In response to 60 days of HDBR, the change in venousconstrictor response to PE in the dorsal hand veins was not significantly different between M and F. Interestingly, the change in constrictor response in the dorsal foot veins (compared to pre HDBR) was approximately 30% greater in the F, whereas the constrictor response was approximately 45% less in the M (p=0.026). HDBR had no influence on the change in dilator response to ACh, or NTG between M and F and between vascular beds. CONCLUSION: These results demonstrate that 60 days of HDBR contributes to sex-related differences in venous function. Importantly, the changes are specific to dorsal foot veins and do not appear to be related to changes in endothelial or smooth muscle function. Previous data from our laboratory indicate that females have an impaired sympathetic response following HDBR. However, the results from the current investigation imply that F maintain the ability to respond to sympathetic stimulation but may not be able to adequately activate a proper response following HDBR.

  6. Evaluation of Head Mounted and Head Down Information Displays During Simulated Mine-Countermeasures Dives to 42 msw

    DTIC Science & Technology

    2008-04-01

    information processing is slowed at each stage by narcosis ( nitrogen and carbon dioxide). It is likely that transferring information from sensory memory to...short term memory. Background noise is likely a factor in distracting the diver from attending to other, important information. Pressure ( narcosis ...Immersion in water increases the ambient pressure of the diving environment and may lead to narcosis . According to Fowler et al., (1985

  7. The Low-Degree Shape of Mercury

    NASA Astrophysics Data System (ADS)

    Perry, M. E.; Neumann, G. A.; Mazarico, E.; Hauck, S. A., II; Solomon, S. C.; Zuber, M. T.; Smith, D. E.; Phillips, R. J.; Margot, J. L.; Johnson, C. L.; Ernst, C. M.; Oberst, J.

    2015-12-01

    The shape of Mercury, particularly when combined with its geoid, provides clues to the planet's internal structure, thermal evolution, and rotational history. Twenty-five million elevation measurements of the northern hemisphere, acquired by the Mercury Laser Altimeter on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft, were combined with 378 occultation measurements of radio-frequency signals from the spacecraft in the planet's southern hemisphere to reveal the low-degree shape of Mercury. We solved for the spherical-harmonic coefficients through degree and order 128 and found that Mercury's mean radius is 2439.36±0.02 km. The offset between the planet's centers of mass and figure is negligible (40±40 m) along the polar axis and modest (140±50 m) in the equatorial plane. Mercury's spherical-harmonic shape spectrum is dominated by degree 2, and the planet's first-order shape is that of a triaxial ellipsoid with semimajor axes a, b, and c. The polar radius, c, is 1.65 km less than (a+b)/2, and the equatorial difference, a-b, is 1.25 km. The long axis is rotated 15° west of Mercury's dynamically defined principal axis. Mercury's geoid is similarly dominated by degree 2 and well described by a triaxial ellipsoid. The degree-2 geoid and shape are highly correlated, but the power spectral density of the geoid at degree 2 is only 1% of its shape counterpart, implying substantial compensation of elevation variations on a global scale and that Mercury is not in hydrostatic equilibrium.

  8. High-Degree Neurons Feed Cortical Computations.

    PubMed

    Timme, Nicholas M; Ito, Shinya; Myroshnychenko, Maxym; Nigam, Sunny; Shimono, Masanori; Yeh, Fang-Chin; Hottowy, Pawel; Litke, Alan M; Beggs, John M

    2016-05-01

    Recent work has shown that functional connectivity among cortical neurons is highly varied, with a small percentage of neurons having many more connections than others. Also, recent theoretical developments now make it possible to quantify how neurons modify information from the connections they receive. Therefore, it is now possible to investigate how information modification, or computation, depends on the number of connections a neuron receives (in-degree) or sends out (out-degree). To do this, we recorded the simultaneous spiking activity of hundreds of neurons in cortico-hippocampal slice cultures using a high-density 512-electrode array. This preparation and recording method combination produced large numbers of neurons recorded at temporal and spatial resolutions that are not currently available in any in vivo recording system. We utilized transfer entropy (a well-established method for detecting linear and nonlinear interactions in time series) and the partial information decomposition (a powerful, recently developed tool for dissecting multivariate information processing into distinct parts) to quantify computation between neurons where information flows converged. We found that computations did not occur equally in all neurons throughout the networks. Surprisingly, neurons that computed large amounts of information tended to receive connections from high out-degree neurons. However, the in-degree of a neuron was not related to the amount of information it computed. To gain insight into these findings, we developed a simple feedforward network model. We found that a degree-modified Hebbian wiring rule best reproduced the pattern of computation and degree correlation results seen in the real data. Interestingly, this rule also maximized signal propagation in the presence of network-wide correlations, suggesting a mechanism by which cortex could deal with common random background input. These are the first results to show that the extent to which a neuron

  9. High-Degree Neurons Feed Cortical Computations

    PubMed Central

    Timme, Nicholas M.; Ito, Shinya; Shimono, Masanori; Yeh, Fang-Chin; Litke, Alan M.; Beggs, John M.

    2016-01-01

    Recent work has shown that functional connectivity among cortical neurons is highly varied, with a small percentage of neurons having many more connections than others. Also, recent theoretical developments now make it possible to quantify how neurons modify information from the connections they receive. Therefore, it is now possible to investigate how information modification, or computation, depends on the number of connections a neuron receives (in-degree) or sends out (out-degree). To do this, we recorded the simultaneous spiking activity of hundreds of neurons in cortico-hippocampal slice cultures using a high-density 512-electrode array. This preparation and recording method combination produced large numbers of neurons recorded at temporal and spatial resolutions that are not currently available in any in vivo recording system. We utilized transfer entropy (a well-established method for detecting linear and nonlinear interactions in time series) and the partial information decomposition (a powerful, recently developed tool for dissecting multivariate information processing into distinct parts) to quantify computation between neurons where information flows converged. We found that computations did not occur equally in all neurons throughout the networks. Surprisingly, neurons that computed large amounts of information tended to receive connections from high out-degree neurons. However, the in-degree of a neuron was not related to the amount of information it computed. To gain insight into these findings, we developed a simple feedforward network model. We found that a degree-modified Hebbian wiring rule best reproduced the pattern of computation and degree correlation results seen in the real data. Interestingly, this rule also maximized signal propagation in the presence of network-wide correlations, suggesting a mechanism by which cortex could deal with common random background input. These are the first results to show that the extent to which a neuron

  10. Evolutionary Dynamics on Degree-Heterogeneous Graphs

    NASA Astrophysics Data System (ADS)

    Antal, T.; Redner, S.; Sood, V.

    2006-05-01

    The evolution of two species with different fitness is investigated on degree-heterogeneous graphs. The population evolves either by one individual dying and being replaced by the offspring of a random neighbor (voter model dynamics) or by an individual giving birth to an offspring that takes over a random neighbor node (invasion process dynamics). The fixation probability for one species to take over a population of N individuals depends crucially on the dynamics and on the local environment. Starting with a single fitter mutant at a node of degree k, the fixation probability is proportional to k for voter model dynamics and to 1/k for invasion process dynamics.

  11. From diploma to degree in photonics

    NASA Astrophysics Data System (ADS)

    Chebbi, Brahim; Grevatt, Treena; Weeks, Robert; Mohammed, Mostefa; Casey, Peter J.; Wahab, Almuhtadi; Al-Azzawi, Abdul

    2004-10-01

    This paper discusses the bridging requirements and the transfer of credits for the graduates of a three year Diploma of Photonics Engineering Technology program entering the Bachelor of Applied Technology degree in photonics. The procedure followed to determine the transfer of credits consisted of two iterations. In the first iteration a detailed comparison of the learning outcomes of the different courses in the diploma and the degree programs was undertaken. A second iteration was performed to compare in more detail the focus of the courses and the theoretical depth of learning the subjects. The difference between the courses from the two programs is used to design two bridging courses.

  12. Degrees Conferred: 2000-01 Update. Informational Memorandum.

    ERIC Educational Resources Information Center

    Wisconsin Univ. System, Madison. Office of Policy Analysis and Research.

    This memorandum contains facts about degrees conferred by institutions in the University of Wisconsin (UW) System in 2000-2001. Overall, the UW System conferred 28,217 degrees in 2000-2001. Of these, 969 were Associate Degrees, and 20,927 were Bachelors Degrees. There were 4,952 Masters Degrees, and 759 Doctoral Degrees, with 610 professional…

  13. Predicting Young Adult Degree Attainment by Late Adolescent Marijuana Use

    PubMed Central

    Staff, Jeremy; Kloska, Deborah D.; Patrick, Megan E.; O’Malley, Patrick M.; Schulenberg, John

    2015-01-01

    Purpose Assess whether infrequent and frequent marijuana use at age 19/20 predicts receipt of educational degrees by the mid 20s, independent of confounding age 18 adolescent risk factors. Methods Data were from the Monitoring the Future study, an annual nationally-representative survey of high school seniors followed into adulthood. Thirteen cohorts (1990 to 2002) of high school seniors were followed longitudinally to their mid 20s (n=4,925; 54% female). We used logistic regression and propensity score matching with successive inclusion of age 18 risk factors and substance use to compare age 19/20 frequent marijuana users (6+ occasions in past 30 days) to non-users, frequent users to infrequent users (1 to 6 occasions), and infrequent users to non-users on their likelihood of degree attainment by the mid 20s. Results Frequent marijuana users were less likely than infrequent users and non-users to earn Bachelor’s degrees, even after controlling for a host of age 18 risk factors (e.g., family socioeconomic background, academic performance, educational expectations, truancy). However, these differences were reduced in magnitude to statistical non-significance when we controlled for age 18 substance use. Across analyses, the proportion reaching this educational milestone did not differ significantly between infrequent users and non-users. Conclusions Results support a growing body of work suggesting that frequent marijuana use predicts a lower likelihood of post-secondary educational attainment, and this difference may originate during secondary school. PMID:26206441

  14. Predictive Factors of Premedical Student Retention and Degree Completion within a Private Undergraduate University

    ERIC Educational Resources Information Center

    Carter, Frances E.

    2010-01-01

    Undergraduate retention and eventual graduation is of paramount importance to universities globally. Approximately 58% of students who began their college career at a four-year institution with the intention of receiving a bachelor's degree actually received that degree in a 6-year timeframe, according to the National Center for Education…

  15. Comparison of 360 degrees and 180 degrees data collection in SPECT imaging.

    PubMed

    Knesaurek, K

    1987-11-01

    The problem of using 360 degrees or 180 degrees data sampling techniques in transaxial SPECT imaging is still to be solved. A theoretical point source study for an ideal response detector has shown, for objects which are close enough to the origin of the reconstructed area, that there are significant differences between sections obtained by different sampling methods. A computer simulation study of line sources in a homogeneous attenuated medium has confirmed the results of clinical studies in which significant image distortion has been observed in 180 degrees sections but not in 360 degrees reconstructed images.

  16. Field measurement of slow metamorphic reaction rates at temperatures of 500 degrees to 600 degrees C

    PubMed

    Baxter; DePaolo

    2000-05-26

    High-temperature metamorphic reaction rates were measured using strontium isotopic ratios of garnet and whole rock from a field site near Simplon Pass, Switzerland. For metamorphic conditions of cooling from 612 degrees +/- 17 degrees C to 505 degrees +/- 15 degrees C at pressures up to 9.1 kilobars, the inferred bulk fluid-rock exchange rate is 1.3(-0.4)(+1.1) x 10(-7) grams of solid reacted per gram of solid per year, several orders of magnitude lower than laboratory-based estimates. The inferred reaction rate suggests that mineral chemistry may lag the evolving conditions in Earth's crust during mountain building.

  17. Attrition in Online and Campus Degree Programs

    ERIC Educational Resources Information Center

    Patterson, Belinda; McFadden, Cheryl

    2009-01-01

    The purpose of this study was to examine how the mode of instructional delivery, campus face-to-face or online, affected dropout relative to students' academic and demographic characteristics. A quantitative study was conducted to analyze the academic and demographic characteristics of newly admitted, matriculated degree-seeking students (N = 640)…

  18. Strategies for Maintaining Associate Degree Nursing Programs.

    ERIC Educational Resources Information Center

    Tilton, Theodore

    As part of the national campaign of the American Nurses Association (ANA) to create two levels of nursing, one for bachelor of science nurses (BSN's) and one for associate degree nurses (ADN's), Illinois has been targeted for a legislative push to change the laws governing nurse licensure, which, if successful, would signal the beginning of the…

  19. Making Sense out of Degree Completion Rates

    ERIC Educational Resources Information Center

    Astin, Alexander W.

    2006-01-01

    It has been more than a decade since the U.S. Congress enacted the "Student Right-to-Know and Campus Security Act," which requires colleges and universities to make public their six-year degree completion rates. Based on the "Student Right-to-Know and Campus Security Act," prospective students and their parents are being encouraged to make…

  20. Researching Research in Master's Degrees in Europe

    ERIC Educational Resources Information Center

    Sin, Cristina

    2012-01-01

    The research dimension of higher education programmes is usually discussed in association with doctoral studies. Against a background of scarce literature investigating research in a Master's degree, this article aims to analyse the place of research in Master's qualifications, first, as envisaged by official European and national documents acting…

  1. Lessons from VET Providers Delivering Degrees

    ERIC Educational Resources Information Center

    Callan, Victor J.; Bowman, Kaye

    2015-01-01

    This report is focused on the strategic, capability and operational reasons why traditional vocational education and training (VET) providers move to the delivery of higher education qualifications in their own right, in addition to their vocational qualifications. It is particularly interested in associate and bachelor degrees. By undertaking six…

  2. Third-Degree Price Discrimination Revisited

    ERIC Educational Resources Information Center

    Kwon, Youngsun

    2006-01-01

    The author derives the probability that price discrimination improves social welfare, using a simple model of third-degree price discrimination assuming two independent linear demands. The probability that price discrimination raises social welfare increases as the preferences or incomes of consumer groups become more heterogeneous. He derives the…

  3. Edison Offers Degrees but No Classes

    ERIC Educational Resources Information Center

    Wald, Matthew L.

    1977-01-01

    Thomas A. Edison College, New Jersey's ninth state college, has awarded associate or bachelor's degrees to more than a thousand students for work completed at other colleges or for knowledge gained on the job or through independent study. It has no faculty, no library and a small office building for a campus--here its evaluation criteria are…

  4. Active Methodology in the Audiovisual Communication Degree

    ERIC Educational Resources Information Center

    Gimenez-Lopez, J. L.; Royo, T. Magal; Laborda, Jesus Garcia; Dunai, Larisa

    2010-01-01

    The paper describes the adaptation methods of the active methodologies of the new European higher education area in the new Audiovisual Communication degree under the perspective of subjects related to the area of the interactive communication in Europe. The proposed active methodologies have been experimentally implemented into the new academic…

  5. Tourism Degree Internships: A Longitudinal Study

    ERIC Educational Resources Information Center

    Busby, Graham

    2003-01-01

    This case study briefly reviews the development of tourism degrees in the United Kingdom before considering the experiences obtained by students on year-long internship programmes over a period of 8 years. Verbatim confidential comments, from students, are provided and specific transferable skills discussed. Whilst some skills can be developed…

  6. Developing Learning Cohorts for Postgraduate Research Degrees

    ERIC Educational Resources Information Center

    Choy, Sarojni; Delahaye, Brian L.; Saggers, Beth

    2015-01-01

    Development of researchers through higher degree research studies is a high priority in most universities. Yet, research about supervision as pedagogy and models of supervision is only recently gained increasing attention. Charged with producing good researchers within very limited resources, academics are constantly looking for more efficient…

  7. Teaching Third-Degree Price Discrimination

    ERIC Educational Resources Information Center

    Round, David K.; McIver, Ron P.

    2006-01-01

    Third-degree price discrimination is taught in almost every intermediate microeconomics class. The theory, geometry, and the algebra behind the concept are simple, and the phenomenon is commonly associated with the sale of many of the goods and services used frequently by students. Classroom discussion is usually vibrant as students can relate…

  8. Bachelor's Degree Recipients Report 1995. AIP Report.

    ERIC Educational Resources Information Center

    Mulvey, Patrick J.; Dodge, Elizabeth

    This document reports on a 1995 survey of students graduating with a bachelor's degree in physics or astronomy as part of an ongoing series of surveys that have been conducted by the American Institute of Physics (AIP) since the 1960s. The data obtained on the 1995 class build upon established trends in students' immediate postbaccalaureate plans…

  9. Enrollments and Degrees Report. AIP Report.

    ERIC Educational Resources Information Center

    Mulvey, Patrick J.; Nicholson, Starr

    In fall 2002, the American Institute of Physics asked the 735 physics departments, the 34 combined physics and astronomy departments, and the 37 separate astronomy departments in the United States to provide information on both their current student enrollments and the degrees they conferred in the previous academic year. Data were received from…

  10. Innovative Degree Programs Matched to City Strengths

    ERIC Educational Resources Information Center

    Sukhatme, Uday

    2011-01-01

    In recent years, IUPUI has steadily acquired a considerable national reputation as an up-and-coming university. Some of the reasons for this recognition include the RISE Initiative and the large number of innovative degree programs recently started at IUPUI based on campus strengths and the priorities of the city of Indianapolis. Some specific…

  11. Multiple degree of freedom optical pattern recognition

    NASA Technical Reports Server (NTRS)

    Casasent, D.

    1987-01-01

    Three general optical approaches to multiple degree of freedom object pattern recognition (where no stable object rest position exists) are advanced. These techniques include: feature extraction, correlation, and artificial intelligence. The details of the various processors are advanced together with initial results.

  12. "What Can I Do with This Degree?"

    ERIC Educational Resources Information Center

    Wartel, Max

    2015-01-01

    As long as the question of what recent graduates can do with their degree is being asked, the need for comprehensive and trustworthy data will exist. Between the White House College Scorecard, the Rubio-Wyden-Warner Student Right to Know Before You Go Act, the USDOE's Title IV Federal Student Aid Programs: Gainful Employment in a Recognized…

  13. Institutional Grants and Baccalaureate Degree Attainment

    ERIC Educational Resources Information Center

    Price, Derek V.; Davis, Ryan J.

    2006-01-01

    While the effects of the shift from need- to merit-based grants on student enrollment and receipt of aid have been examined thoroughly by a number of analysts, very few recent reports have examined the effects of these grants on students' persistence towards completing bachelor's degrees. To examine this issue, this report explores the linkages…

  14. Toward the Ideal Professional Master's Degree Program.

    ERIC Educational Resources Information Center

    Russell, Maria P.

    1999-01-01

    Outlines work accomplished at the 1998 National Communication Association Summer Conference, presenting a model for a professional master's-degree program in public relations that integrates outcomes, assessment, curriculum, and pedagogy. Outlines program outcomes, curriculum, essential curriculum-content areas, pedagogical approaches, and…

  15. Strategies for Evaluating Undergraduate Degree Programs

    ERIC Educational Resources Information Center

    Coyle, James P.

    2011-01-01

    Evaluating higher education degree programs is an arduous task. This paper suggests innovative strategies for addressing four types of challenges that commonly occur during program evaluation: identifying theoretical models for evaluation, balancing potentially conflicting standards, accommodating faculty differences, and aligning courses.…

  16. Preparing students for degree-level physics

    NASA Astrophysics Data System (ADS)

    Fairhurst, David; Lloyd, Steve

    2013-11-01

    On behalf of the physics department at Nottingham Trent University (NTU), I would like to reply to the letter from Helen Hare on the need for foundation programmes to prepare students for degree-level physics courses ("Firm foundations", September p23).

  17. Three Degree of Freedom Parallel Mechanical Linkage

    NASA Technical Reports Server (NTRS)

    Adelstein, Bernard D. (Inventor)

    1998-01-01

    A three degree of freedom parallel mechanism or linkage that couples three degree of freedom translational displacements at an endpoint, such as a handle, a hand grip, or a robot tool, to link rotations about three axes that are fixed with respect to a common base or ground link. The mechanism includes a three degree of freedom spherical linkage formed of two closed loops, and a planar linkage connected to the endpoint. The closed loops are rotatably interconnected, and made of eight rigid links connected by a plurality of single degree of freedom revolute joints. Three of these revolute joints are base joints and are connected to a common ground. such that the axis lines passing through the revolute joints intersect at a common fixed center point K forming the center of a spherical work volume in which the endpoint is capable of moving. 'Me three degrees of freedom correspond to the spatial displacement of the endpoint, for instance. The mechanism provides a new overall spatial kinematic linkage composed of a minimal number of rigid links and rotary joints. The mechanism has improved mechanical stiffness, and conveys mechanical power bidirectionally between the human operator and the electromechanical actuators. It does not require gears, belts. cable, screw or other types of transmission elements, and is useful in applications requiring full backdrivability. Thus, this invention can serve as the mechanical linkage for actively powered devices such as compliant robotic manipulators and force-reflecting hand controllers, and passive devices such as manual input devices for computers and other systems.

  18. The Degree Gap: Are University Graduates Making Full Use of Their Degrees? Report 09-23

    ERIC Educational Resources Information Center

    Angeli, Mallory; Fuller, Ryan

    2009-01-01

    California's degree gap is a growing concern. According to recent reports and news articles comparing the number of degrees awarded with the jobs expected in the coming decade, California will not have enough university graduates to meet the needs of the labor market. Previous work by the California Postsecondary Education Commission (CPEC) showed…

  19. Lessons Learned: Creating an Online Business Degree from a Successful On-Campus Business Degree

    ERIC Educational Resources Information Center

    Cordeiro, William P.; Muraoka, Dennis

    2015-01-01

    The horse has left the barn. Distance education is here to stay and the number of degree programs offered online is growing rapidly. California State University Channel Islands (CI) admitted its first students in 2002, and the undergraduate and graduate degrees in business were among its first program offerings. From its inception, the…

  20. Astronomy Enrollments and Degrees: Results from the 2012 Survey of Astronomy Enrollments and Degrees. Focus On

    ERIC Educational Resources Information Center

    Mulvey, Patrick; Nicholson, Starr

    2014-01-01

    Interest in astronomy degrees in the U.S. remains strong, with astronomy enrollments at or near all-time highs for the 2012-13 academic year. The total number of students taking an introductory astronomy course at a degree-granting physics or astronomy department is approaching 200,000. Enrollments in introductory astronomy courses have been…

  1. Predictors of Accounting Salaries: A Comparison of Bachelor Degree Graduate Salaries with Associate Degree Graduate Salaries

    ERIC Educational Resources Information Center

    Tickell, Geoffrey

    2009-01-01

    This paper reports on an investigation comparing the employment salary of bachelor degree in accounting graduates with associate degree in accounting graduates two years after their graduation. Using hierarchical regression analyses, this study shows the predictive strength of participants' academic qualifications, age, gender, GPA, professional…

  2. Physics Undergraduate Degrees: Results from the 2008 Survey of Enrollments and Degrees. Focus On

    ERIC Educational Resources Information Center

    Mulvey, Patrick J.; Nicholson, Starr

    2011-01-01

    The Statistical Research Center of the American Institute of Physics conducts an annual census of all degree-granting physics departments in the United States and Puerto Rico. The survey, collecting data from the 754 departments that granted bachelor's degrees in the class of 2008, had a 97% response rate. Estimates were derived and included in…

  3. Physics Bachelor's Degrees: Results from the 2010 Survey of Enrollments and Degrees. Focus On

    ERIC Educational Resources Information Center

    Mulvey, Patrick J.; Nicholson, Starr

    2012-01-01

    The Statistical Research Center of the American Institute of Physics conducts an annual census of all degree-granting physics departments in the United States and Puerto Rico. The survey had a 95% response rate from the 751 departments that granted physics bachelor's degrees in the class of 2010. Results show that the number of physics bachelor's…

  4. South Carolina Pharmacy Practitioner Opinion of Entry Level Degree and Interest in an Advanced Degree.

    ERIC Educational Resources Information Center

    Karig, Arnold W.; And Others

    1982-01-01

    A survey of South Carolina pharmacists investigated the desired entry level pharmacy degree, years of study required, perceived adequacy of the respondents' current education, current pursuit of credit courses and continuing education programs, and interest in obtaining advanced degrees. Results suggest an off-campus program would be…

  5. Separation of Degrees: State-By-State Analysis of Teacher Compensation for Master's Degrees

    ERIC Educational Resources Information Center

    Roza, Marguerite; Miller, Raegen

    2009-01-01

    How much money is tied up in master's degrees? A 2007 study estimated that 2.1 percent of all current expenditures can be attributed to teacher compensation related to master's degrees. Seen another way, the master's bump costs the average school district $174 per pupil. These national figures conceal substantial variation among states in the…

  6. Pathways to a Four-Year Degree: Determinants of Degree Completion among Socioeconomically Disadvantaged Students.

    ERIC Educational Resources Information Center

    Cabrera, Alberto F.; Burkum, Kurt R.; La Nasa, Steven M.

    The High School Sophomore Cohort of 1980 followed nine different pathways to a 4-year college degree. These paths were formed by a combination of different levels of academic preparation secured in high school and the first type of postsecondary institution attended. The pathway most likely to lead to a 4-year degree is one defined by acquiring…

  7. Currently available medical engineering degrees in the UK. Part 1: Undergraduate degrees.

    PubMed

    Joyce, T

    2009-05-01

    This paper reviews mechanical-engineering-based medical engineering degrees which are currently provided at undergraduate level in the UK. At present there are 14 undergraduate degree programmes in medical engineering, offered by the University of Bath, University of Birmingham, University of Bradford, Cardiff University, University of Hull, Imperial College London, University of Leeds, University of Nottingham, University of Oxford, Queen Mary University of London, University of Sheffield, University of Southampton, University of Surrey, and Swansea University. All these undergraduate courses are delivered on a full-time basis, both 3 year BEng and 4 year MEng degrees. Half of the 14 degree courses share a core first 2 years with a mechanical engineering stream. The other seven programmes include medical engineering modules earlier in their degrees. Within the courses, a very wide range of medical-engineering-related modules are offered, although more common modules include biomaterials, biomechanics, and anatomy and physiology.

  8. 6 K Cryocooler Program

    NASA Technical Reports Server (NTRS)

    Gully, Willy; Herrero, Fred (Technical Monitor)

    2001-01-01

    The report summarizes experimental and theoretical work on an Oxford type Stirling Cycle mechanical precooler operating in the temperature range of 13-20 degrees Kelvin. It includes measurements of the thermal losses of particle regenerators made from lead, and rare earth and rare earth alloys in an operating three stage cryocooler. A 6 K hybrid cooler is designed using the technical information gathered on regenerator performance.

  9. Degree correlations in signed social networks

    NASA Astrophysics Data System (ADS)

    Ciotti, Valerio; Bianconi, Ginestra; Capocci, Andrea; Colaiori, Francesca; Panzarasa, Pietro

    2015-03-01

    We investigate degree correlations in two online social networks where users are connected through different types of links. We find that, while subnetworks in which links have a positive connotation, such as endorsement and trust, are characterized by assortative mixing by degree, networks in which links have a negative connotation, such as disapproval and distrust, are characterized by disassortative patterns. We introduce a class of simple theoretical models to analyze the interplay between network topology and the superimposed structure based on the sign of links. Results uncover the conditions that underpin the emergence of the patterns observed in the data, namely the assortativity of positive subnetworks and the disassortativity of negative ones. We discuss the implications of our study for the analysis of signed complex networks.

  10. Jamming in complex networks with degree correlation

    NASA Astrophysics Data System (ADS)

    Pastore Y Piontti, Ana; Braunstein, Lidia; Macri, Pablo

    2012-02-01

    We study the effects of the degree-degree correlations on the pressure congestion J for a diffusive transport process on scale free complex networks. Using the gradient network approach we find that the pressure congestion for disassortative (assortative) networks is lower (bigger) than the one for uncorrelated networks which allow us to affirm that disassortative networks enhance transport through them. This result agree with the fact that many real world transportation networks naturally evolve to this kind of correlation. We explain our results showing that for the disassortative case the clusters in the gradient network turn out to be as much elongated as possible, reducing the pressure congestion J and observing the opposite behavior for the assortative case. Finally, we apply our transportation process to real world networks, and the results agree with our findings for model networks.

  11. Jamming in complex networks with degree correlation

    NASA Astrophysics Data System (ADS)

    Pastore y Piontti, Ana L.; Braunstein, Lidia A.; Macri, Pablo A.

    2010-10-01

    We study the effects of the degree-degree correlations on the pressure congestion J when we apply a dynamical process on scale free complex networks using the gradient network approach. We find that the pressure congestion for disassortative (assortative) networks is lower (bigger) than the one for uncorrelated networks which allow us to affirm that disassortative networks enhance transport through them. This result agree with the fact that many real world transportation networks naturally evolve to this kind of correlation. We explain our results showing that for the disassortative case the clusters in the gradient network turn out to be as much elongated as possible, reducing the pressure congestion J and observing the opposite behavior for the assortative case. Finally we apply our model to real world networks, and the results agree with our theoretical model.

  12. Role Preparation of Associate Degree Graduates.

    ERIC Educational Resources Information Center

    Stokes, Lillian G.

    The role of associate degree nursing (ADN) programs has changed dramatically in their 30 years of existence. The number of ADN graduates increased from 260 in 1954 to 36,434 in 1980, and 47.8% of all nursing graduates in 1980 came from ADN programs, as compared to 0.9% in 1954. These graduates have the best record of employment five years after…

  13. Genocide as a matter of degree.

    PubMed

    Campbell, Bradley

    2011-12-01

    This article employs Max Weber's ideal-type method to classify genocides based on their degree of mass killing, unilateralism, and ethnic liability. The identification of the elements of genocide draws from a general theory of genocide (Campbell 2009, 2010) and from theories of social control employing Donald Black's (1995, 1998) theoretical approach, known as pure sociology. Because these theories identify the social features associated with each element of genocide, they can explain the form genocides take.

  14. Spirit 360-Degree View, Sol 388

    NASA Technical Reports Server (NTRS)

    2005-01-01

    NASA's Mars Exploration Rover Spirit used its navigation camera to take the images combined into this 360-degree view of the rover's surroundings on Spirit's 388th martian day, or sol (Feb. 4, 2005). Spirit had driven about 13 meters (43 feet) uphill toward 'Cumberland Ridge' on this sol. This location is catalogued as Spirit's Site 102, Position 513. The view is presented in a cylindrical projection with geometric and brightness seam correction.

  15. Spirit 360-Degree View, Sol 388 (polar)

    NASA Technical Reports Server (NTRS)

    2005-01-01

    NASA's Mars Exploration Rover Spirit used its navigation camera to take the images combined into this 360-degree view of the rover's surroundings on Spirit's 388th martian day, or sol (Feb. 4, 2005). Spirit had driven about 13 meters (43 feet) uphill toward 'Cumberland Ridge' on this sol. This location is catalogued as Spirit's Site 102, Position 513. The view is presented in a cylindrical projection with geometric and brightness seam correction.

  16. Spirit 360-Degree View, Sol 388 (vertical)

    NASA Technical Reports Server (NTRS)

    2005-01-01

    NASA's Mars Exploration Rover Spirit used its navigation camera to take the images combined into this 360-degree view of the rover's surroundings on Spirit's 388th martian day, or sol (Feb. 4, 2005). Spirit had driven about 13 meters (43 feet) uphill toward 'Cumberland Ridge' on this sol. This location is catalogued as Spirit's Site 102, Position 513. The view is presented in a vertical projection with geometric and brightness seam correction.

  17. Law Schools Customize Degrees to Students' Taste

    ERIC Educational Resources Information Center

    Schmidt, Peter

    2009-01-01

    Going to law school to get a law degree has become a little like going to an ice-cream parlor for a scoop of vanilla. Plenty of people still do it, but many schools' brochures--like the elaborate flavor-and-topping menus on ice-cream parlor walls--now tempt them with something different, something more. Law students can have their "juris doctor"…

  18. Nuclear engineering enrollments and degrees, 1994: Appendixes

    SciTech Connect

    1995-05-01

    This survey is designed to include those programs sponsored by the Department of Energy. The survey is designed to include those programs offering a major in nuclear engineering or course work equivalent to a major in other engineering disciplines that prepare the graduates to perform as nuclear engineers. This survey provides data on nuclear engineering enrollments and degrees for use in labor market analyses, information on education programs for students, and information on new graduates to employers, government agencies, academia and professional societies.

  19. Algebraic aspects of the computably enumerable degrees.

    PubMed Central

    Slaman, T A; Soare, R I

    1995-01-01

    A set A of nonnegative integers is computably enumerable (c.e.), also called recursively enumerable (r.e.), if there is a computable method to list its elements. The class of sets B which contain the same information as A under Turing computability (degree of A, and a degree is c.e. if it contains a c.e. set. The extension of embedding problem for the c.e. degrees R = (R, <, 0, 0') asks, given finite partially ordered sets P is a subset of Q with least and greatest elements, whether every embedding of P into can be extended to an embedding of Q into R. Many of the most significant theorems giving an algebraic insight into R have asserted either extension or nonextension of embeddings. We extend and unify these results and their proofs to produce complete and complementary criteria and techniques to analyze instances of extension and nonextension. We conclude that the full extension of embedding problem is decidable. PMID:11607508

  20. Degree program alternatives for fulltime employees

    SciTech Connect

    Strong, K.; Thayer, M.

    1992-01-01

    Los Alamos National Laboratory supports and sponsors degree programs for employees in order to help attract and retain the staff required to succeed in its mission. The support for these programs is provided by the Employee and Organization Development Group (HRD-3) which oversees the development, implementation, and delivery. This paper defines successful programs and suggests techniques to achieve a quality product. In order to attract the staff that it needs, the Laboratory has long recognized that educational opportunities must be available to its employees. To meet this need, the University of New Mexico (UNM) Los Alamos Center for Graduate Studies (LACGS) was established in 1956 and represents a unique cooperative venture between the Laboratory and UNM. The LACGS is funded primarily from the Laboratory. Over the years the LACGS has been a primary source of graduate degree programs for Laboratory employees, but until recently most offerings were not systematic or sequential. Nor was there any method to increase the variety of degree options.

  1. Degree program alternatives for fulltime employees

    SciTech Connect

    Strong, K.; Thayer, M.

    1992-03-01

    Los Alamos National Laboratory supports and sponsors degree programs for employees in order to help attract and retain the staff required to succeed in its mission. The support for these programs is provided by the Employee and Organization Development Group (HRD-3) which oversees the development, implementation, and delivery. This paper defines successful programs and suggests techniques to achieve a quality product. In order to attract the staff that it needs, the Laboratory has long recognized that educational opportunities must be available to its employees. To meet this need, the University of New Mexico (UNM) Los Alamos Center for Graduate Studies (LACGS) was established in 1956 and represents a unique cooperative venture between the Laboratory and UNM. The LACGS is funded primarily from the Laboratory. Over the years the LACGS has been a primary source of graduate degree programs for Laboratory employees, but until recently most offerings were not systematic or sequential. Nor was there any method to increase the variety of degree options.

  2. Is That Graduate Degree Worth It? Comparing the Recruitment of Undergraduate and Graduate Degree Job Applicants

    NASA Astrophysics Data System (ADS)

    Richardson, R. M.

    2001-12-01

    One could argue from a business prospective that colleges and universities are not working hard enough to train students for life in the business and civic world, at either the undergraduate or graduate levels. What is it that employers are looking for in students? How different are the skills and attributes employers are looking for between undergraduate and graduate students? How unique are the geosciences in this respect? At the undergraduate level recruiters have spoken loud and clear about what they want. According to the dean of the business school here at the University of Arizona, recruiters at the undergraduate degree level in business base less than half of their hiring decision on specific content knowledge in the discipline, and correspondingly more than half on the so-called soft skills ... ability to apply knowledge in new situations, ability to think critically, ability to communicate with others in both written and oral forms, ability to work in teams, ability to work with a diverse set of employees and customers (especially, but not limited to, the global job market), etc. How true is this at the graduate level, where students have typically spent 4-6 years specializing in a discipline? Is there a set of fundamental knowledge that employers are looking for at the graduate level? Are the so-called soft skills correspondingly less important? I will present results from a survey of graduate programs and industry recruiters addressing these questions, and highlight the areas of overlap and difference between undergraduates and graduates looking for jobs. I will concentrate specifically on jobs in the oil industry and on both masters and Ph.D. programs.

  3. Double Degrees: Double the Trouble or Twice the Return?

    ERIC Educational Resources Information Center

    Russell, A. Wendy; Dolnicar, Sara; Ayoub, Marina

    2008-01-01

    Double degrees (also called joint or combined degrees)--programs of study combining two bachelor degrees--are increasingly popular in Australian universities, particularly among women. A case study using qualitative and quantitative surveys of current and past double degree students is presented. The study indicates that double degrees benefit…

  4. Converting between [Degrees]C and [Degrees]F: A Teachable Moment

    ERIC Educational Resources Information Center

    Day, Lawrence

    2007-01-01

    Converting between degrees Celsius and degrees Fahrenheit isn't difficult. Remembering when to multiply by 5/9 or 9/5 and whether you have to add 32 or subtract 32 makes it fairly easy. Sometimes, though, fairly easy isn't easy enough. Students have trouble remembering the order of operations: "Do I add or subtract 32, and is that before or after…

  5. Geologic map of the Dillon 1 degree by 2 degrees Quadrangle, Idaho and Montana

    USGS Publications Warehouse

    Ruppel, E.T.; Lopez, D.A.; O'Neill, J. M.

    1993-01-01

    The digital ARC/INFO databases included in this website provide a GIS database for the geologic map of the Dillon 1 degree by 2 degree quadrangle of southwest Montana and east-central Idaho. The geologic map was originally published as U.S. Geological Survey Miscellaneous Investigations Series Map I-1803-H. This website directory contains ARC/INFO format files that can be used to query or display the geology of USGS Map I-1803-H with GIS software.

  6. Research Related to Multi Degree of Freedom Magnetic Suspensions. Degree awarded by Old Dominion Univ. Aug. 1997

    NASA Technical Reports Server (NTRS)

    Britcher, Colin; Yang, Yan

    1997-01-01

    This thesis covers the activities associated with (1) recommissioning of the 6-inch Magnetic Suspension and Balance System (MSBS) and (2) enhancing the Annular Suspension and Pointing System (ASPS). These activities continue the program of research in the multi degree of freedom magnetic suspension program at Old Dominion University. The 6-inch MSBS is a large gap magnetic suspension system used as a model support and balance system in wind tunnels. The first stage of recommissioning of the 6-inch MSBS for the 6-inch subsonic wind tunnel is performed. Experimental data and computational results for the magnetic field distribution of the MSBS are given and compared with the estimated magnetic field strength. The comparison indicates that the magnet system is still operating as designed. The Electromagnetic Position Sensor used in the 6-inch MSBS is analyzed before its find reinstatement. The ASPS is a small gap magnetic suspension system providing orientation, mechanical isolation and fine pointing of space payloads. The control system of the ASPS is improved by designing a new code to realize red time control over the system. The original Proportional-Derivative controller is upgraded to a Proportional-Integral-Derivative controller. This progress leads to a system which is more stable and robust with less noise. This new controller is generic and can be adapted to the 6-inch MSBS. Finally, future work on these two systems is proposed.

  7. Spirit 360-Degree View on Sol 409

    NASA Technical Reports Server (NTRS)

    2005-01-01

    NASA's Mars Exploration Rover Spirit used its navigation camera to take the images combined into this 360-degree view of the rover's surroundings on Spirit's 409th martian day, or sol (Feb. 26, 2005). Spirit had driven 2 meters (7 feet) on this sol to get in position on 'Cumberland Ridge' for looking into 'Tennessee Valley' to the east. This location is catalogued as Spirit's Site 108. Rover-wheel tracks from climbing the ridge are visible on the right. The summit of 'Husband Hill' is at the center, to the south. This view is presented in a cylindrical projection with geometric and brightness seam correction.

  8. Degree of correlation inside a financial market

    NASA Astrophysics Data System (ADS)

    Mantegna, Rosario Nunzio

    1997-05-01

    I present an empirical study of the correlations observed between pairs of time series of stock prices in the New York Stock Exchange. I verify that various degrees of correlations or anti-correlations are present inside a financial market and I study the time evolution of these correlations. I briefly discuss how these empirical observations might be consistent with the well accepted hypothesis of absence of arbitrage in an efficient financial market (i.e. that there is no way of extracting money from the market in a continuous way without risk).

  9. Two degree of freedom camera mount

    NASA Technical Reports Server (NTRS)

    Ambrose, Robert O. (Inventor)

    2003-01-01

    A two degree of freedom camera mount. The camera mount includes a socket, a ball, a first linkage and a second linkage. The socket includes an interior surface and an opening. The ball is positioned within an interior of the socket. The ball includes a coupling point for rotating the ball relative to the socket and an aperture for mounting a camera. The first and second linkages are rotatably connected to the socket and slidably connected to the coupling point of the ball. Rotation of the linkages with respect to the socket causes the ball to rotate with respect to the socket.

  10. Measurement of LINAC 90 degrees head leakage radiation TVL values.

    PubMed

    Li, Zuofeng; Mutic, Sasa; Low, Daniel

    2006-09-01

    One of the key components in modern LINAC room shielding design is the amount of 90 degrees head leakage radiation levels. With the general clinical acceptance of intensity-modulated radiation therapy (IMRT) technique, accurate knowledge of this quantity has become even more important. Measurement of 90 degrees head leakage radiation of medical linear accelerators can be technically challenging due to the low dose rate causing poor signal-to-noise ratios in most detectors. 90 degrees leakage tenth-value layer (TVL) values in concrete have not been reported for the Elekta linear accelerators. This report describes our measurements of 90 degrees leakage TVL values for 6, 10, and 18 MV x-ray beams for an Elekta Precise Treatment System. A large-volume (1000 cm3) unpressurized ionization chamber and a high sensitivity electrometer, together with a separate chamber bias power supply, were used in these measurements in order to maximize the signal-to-noise ratio. A lead enclosure, of minimum thickness 10 cm, was constructed inside the treatment room to house the ion chamber to reduce the influence of room-scattered radiation. A square aperture of 10 X 10 cm2 area was left in the shield and aimed towards the accelerator head. Measurements were performed with the chamber placed at approximately 2 m from the accelerator isocenter. Concrete slabs with individual dimensions of approximately 40 X 40 cm2 cross-sectional area and 5 cm thickness were placed between the accelerator head and the ion chamber for these measurements. The measurements were performed with total concrete thickness of up to 80 cm, so that values up to the third TVL were measured. These measurements showed thatthe first concrete TVL values are 22, 23, and 28 cm (8.6, 9.1, and 10.5 in.) for 6, 10, and 18 MV beams, while the average of the first 3 TVL's were 25, 26, and 29 cm (9.9, 10.2, and 11.5 in.). Measured values agreed to within 10% of previously reported values for Varian linear accelerators for

  11. Time-dependent degree-degree correlations in epileptic brain networks: from assortative to dissortative mixing.

    PubMed

    Geier, Christian; Lehnertz, Klaus; Bialonski, Stephan

    2015-01-01

    We investigate the long-term evolution of degree-degree correlations (assortativity) in functional brain networks from epilepsy patients. Functional networks are derived from continuous multi-day, multi-channel electroencephalographic data, which capture a wide range of physiological and pathophysiological activities. In contrast to previous studies which all reported functional brain networks to be assortative on average, even in case of various neurological and neurodegenerative disorders, we observe large fluctuations in time-resolved degree-degree correlations ranging from assortative to dissortative mixing. Moreover, in some patients these fluctuations exhibit some periodic temporal structure which can be attributed, to a large extent, to daily rhythms. Relevant aspects of the epileptic process, particularly possible pre-seizure alterations, contribute marginally to the observed long-term fluctuations. Our findings suggest that physiological and pathophysiological activity may modify functional brain networks in a different and process-specific way. We evaluate factors that possibly influence the long-term evolution of degree-degree correlations.

  12. A 17 degree of freedom anthropomorphic manipulator

    NASA Technical Reports Server (NTRS)

    Vold, Havard I.; Karlen, James P.; Thompson, Jack M., Jr.; Farrell, James D.; Eismann, Paul H.

    1989-01-01

    A 17 axis anthropomorphic manipulator, providing coordinated control of two seven degree of freedom arms mounted on a three degree of freedom torso-waist assembly, is presented. This massively redundant telerobot, designated the Robotics Research K/B-2017 Dexterous Manipulator, employs a modular mechanism design with joint-mounted actuators based on brushless motors and harmonic drive gear reducers. Direct joint torque control at the servo level causes these high-output joint drives to behave like direct-drive actuators, facilitating the implementation of an effective impedance control scheme. The redundant, but conservative motion control system models the manipulator as a spring-loaded linkage with viscous damping and rotary inertia at each joint. This approach allows for real time, sensor-driven control of manipulator pose using a hierarchy of competing rules, or objective functions, to avoid unplanned collisions with objects in the workplace, to produce energy-efficient, graceful motion, to increase leverage, to control effective impedance at the tool or to favor overloaded joints.

  13. Degree of satisfaction among hearing aid users

    PubMed Central

    Mondelli, Maria Fernanda Capoani Garcia; Rocha, Andressa Vital; Honório, Heitor Marques

    2013-01-01

    Summary Introduction: Hearing loss (HL) is defined as the complete or partial loss of hearing ability. Aims: To characterize (1) the degree of satisfaction among adult and elderly hearing aid (HA) users who were treated by a public hearing health service and (2) the relationship between satisfaction and the variables of gender, age, degree of HL, and type of HA. Method: The clinical and experimental study included the administration of the Satisfaction with Amplification in Daily Life (SADL) questionnaire to 110 patients who had used HAs for more than 3 months and were 18 years of age or older. Results: Test patients were sex-balanced (48% were women) and had a mean age of 67 years. A relatively high incidence of sensorineural moderate HL was detected in the study patients (66%) and device B was the most commonly used HA type (48%). No significant differences were evident between HA satisfaction and sex. The importance placed on services/costs and personal image varied between age groups. Correlation was evident at all levels between user satisfaction and amplification. Decreased satisfaction was observed in individuals with severe and/or profound HL. The type of HA used yielded statistically significant differences in the positive effects referring. Conclusion: No correlations were evident between the different factors proposed. HA users exhibited high levels of satisfaction in all SADL areas. PMID:25991994

  14. The WIYN One Degree Imager: an update

    NASA Astrophysics Data System (ADS)

    Harbeck, Daniel R.; Jacoby, George H.; Muller, Gary; Sawyer, Dave; Harmer, Charles; Yeatts, Andrey; Cavin, John; Corson, Charles

    2008-07-01

    The WIYN Consortium is building the One Degree Imager (ODI) for its 3.5m telescope, located at Kitt Peak, Arizona, USA). ODI will utilize both the excellent image quality and the one degree field of view of the WIYN telescope. Image quality will be actively improved by localised tip/tilt image motion stabilisation using a novel concept of Orthogonal Transfer Array (OTA) CCDs, which are a new detector type jointly developed with the PanSTARRS project. Its anticipated median image quality of <= 0.55" in the R band will make ODI a unique and competitive instrument in the landscape of the next generation of large field imagers. A conceptual design of ODI was presented earlier at SPIE.1 In the meantime, this concept matured, the ODI project has been fully funded, and it has entered the construction phase. A prototype camera (QUOTA) with a field of view of 16'x16' has already seen first star light in fall 2006. In this paper we report on the evolution of ODI's definition, the design of its components, the status of the OTA detector development, and the path towards first light in early 2010. In accompanying papers we detail the design of the ODI's optical corrector, the mechanical structures, and the software & instrument system control design.

  15. Epidemics on a weighted network with tunable degree-degree correlation.

    PubMed

    Lopes, Fabio Marcellus

    2014-07-01

    We propose a weighted version of the standard configuration model which allows for a tunable degree-degree correlation. A social network is modeled by a weighted graph generated by this model, where the edge weights indicate the intensity or type of contact between the individuals. An inhomogeneous Reed-Frost epidemic model is then defined on the network, where the inhomogeneity refers to different disease transmission probabilities related to the edge weights. By tuning the model we study the impact of different correlation patterns on the network and epidemics therein. Our results suggest that the basic reproduction number R0 of the epidemic increases (decreases) when the degree-degree correlation coefficient ρ increases (decreases). Furthermore, we show that such effect can be amplified or mitigated depending on the relation between degree and weight distributions as well as the choice of the disease transmission probabilities. In addition, for a more general model allowing additional heterogeneity in the disease transmission probabilities we show that ρ can have the opposite effect on R0.

  16. 'Big Crater' in 360-degree panorama

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The crater dubbed 'Big Crater', approximately 2200 meters (7200 feet)away was imaged by the Imager for Mars Pathfinder (IMP) as part of a 360-degree color panorama, taken over sols 8, 9 and 10. 'Big Crater' is actually a relatively small Martian crater to the southeast of the Mars Pathfinder landing site. It is 1500 meters (4900 feet) in diameter, or about the same size as Meteor Crater in Arizona.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

  17. Research on image scrambling degree evaluation method

    NASA Astrophysics Data System (ADS)

    Bai, Sen; Liao, Xiaofeng; Chen, Jinyu; Liu, Yijun; Wang, Xiao

    2005-12-01

    This paper discussed the evaluation problem of image scrambling degree (ISD). Inspired by the evaluation method of image texture characteristics, three new metrics for assessing objectively the ISD were proposed. The first method utilized the performance of energy concentration of Walsh transformation (WT), which took into account the properties that a good ISD measurement method should be contented. The second method used angular second moment (ASM) of image gray level co-occurrence matrix (GLCM). The third method combined the entropy of GLCM with image texture characteristic. Experimental results show that the proposed metrics are effective to assess the ISD, which correlates well with subjective assessment. Considering the computational complexity, the first evaluation method based on WT is remarkably superior to the method based on ASM and GLCM in terms of the time cost.

  18. Happiness, Psychology, and Degrees of Realism.

    PubMed

    Lavazza, Andrea

    2016-01-01

    The recent emphasis on a realist ontology that cannot be overshadowed by subjectivist or relativist perspectives seems to have a number of consequences for psychology as well. My attempt here is to analyse the relationship between happiness as a state of the individual and the states of the external world and the brain events related to (or, in some hypotheses, causally responsible for) its occurrence. It can be maintained that different degrees of realism are suitable to describe the states of happiness and this fact might have relevant psychological implications, namely for the so-called positive psychology. This is especially true now that there are methods available to induce subjective states of happiness unrelated to the external conditions usually taken to be linked to such states.

  19. 360 degree b/w 'Monster Pan'

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This 360 degree 'monster' panorama was taken by the deployed Imager for Mars Pathfinder (IMP) on Sol 3. All three petals, the perimeter of the deflated airbags, deployed rover Sojourner, forward and backward ramps and prominent surface features are visible. The IMP stands 1.8 meters over the Martian surface. The curvature and misalignment of several sections are due to image parallax.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

  20. Happiness, Psychology, and Degrees of Realism

    PubMed Central

    Lavazza, Andrea

    2016-01-01

    The recent emphasis on a realist ontology that cannot be overshadowed by subjectivist or relativist perspectives seems to have a number of consequences for psychology as well. My attempt here is to analyse the relationship between happiness as a state of the individual and the states of the external world and the brain events related to (or, in some hypotheses, causally responsible for) its occurrence. It can be maintained that different degrees of realism are suitable to describe the states of happiness and this fact might have relevant psychological implications, namely for the so-called positive psychology. This is especially true now that there are methods available to induce subjective states of happiness unrelated to the external conditions usually taken to be linked to such states. PMID:27536261

  1. Vocational Certificates and College Degrees. ERIC Digest No. 212.

    ERIC Educational Resources Information Center

    Brown, Bettina Lankard

    Many studies have verified that education beyond high school results in higher earnings. The highest earnings benefits depend upon certification or degree achievement. Not obtaining a degree results in some penalty: individuals who have some college credit but no degree earn less than associate degree holders. Professional and vocational…

  2. Degree Partnerships in the BC Context. Special Report, December 2006

    ERIC Educational Resources Information Center

    Gaber, Devron

    2006-01-01

    Degree partnership is a term used to describe a variety of models that provide a guarantee to students who maintain adequate grades in a college program of continuation of degree studies at another institution. This "guarantee" that space will be available for degree completion at another institution separates degree partnerships from…

  3. 45 CFR 2400.46 - Special consideration: second master's degree.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 4 2012-10-01 2012-10-01 false Special consideration: second master's degree... consideration: second master's degree. The Foundation may award Senior Fellowships to applicants who are seeking their second master's degrees providing that the applicants' first master's degree was obtained at...

  4. 45 CFR 2400.46 - Special consideration: second master's degree.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 4 2014-10-01 2014-10-01 false Special consideration: second master's degree... consideration: second master's degree. The Foundation may award Senior Fellowships to applicants who are seeking their second master's degrees providing that the applicants' first master's degree was obtained at...

  5. 45 CFR 2400.46 - Special consideration: second master's degree.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 4 2013-10-01 2013-10-01 false Special consideration: second master's degree... consideration: second master's degree. The Foundation may award Senior Fellowships to applicants who are seeking their second master's degrees providing that the applicants' first master's degree was obtained at...

  6. Do angles of obliquity apply to 30 degrees scattered radiation from megavoltage beams?

    PubMed

    Biggs, Peter J; Styczynski, John R

    2008-10-01

    The angle of obliquity is used in radiation shielding calculations to account for the longer path length x rays will see when obliquely incident on the protective barrier. According to the National Council on Radiation Protection and Measurements (NCRP), use of the angle of obliquity is explicitly assumed for primary radiation, so that an angle of obliquity for secondary radiation is never addressed. However, in the example section of the latest report, it specifically recommends against using an angle of obliquity for scattered radiation. To check this assumption, the existence or not of an angle of obliquity for scattered radiation has been investigated for bremsstrahlung x-ray beams of 4, 6, 10, 15, and 18 MV and for barriers consisting of concrete, lead, and steel using a Monte Carlo approach. The MCNP Monte Carlo code, v4.2C, has been used to generate scattered radiation at 30 degrees from a water phantom and incident on a secondary barrier at the same angle relative to the normal to the barrier. The barrier thickness was increased from zero to a thickness sufficient to reduce the fluence (f4 tally) to <10(-3). A transmission curve was created for each energy-barrier material combination by normalizing to zero thickness. The results for the first tenth-value layer (TVL) in concrete (5 energies) show an average angle of obliquity of 21.7 degrees +/- 5.6 degrees , and for the first two TVLs averaged 29.7 degrees +/- 3.9 degrees . The results for the first TVL in lead (3 energies) show an average angle of obliquity of 27.7 degrees +/- 4.0 degrees , and for the first two TVLs averaged 20.5 degrees +/- 5.8 degrees . There are no data in the NCRP reports for 30 degrees scattered radiation attenuated by steel with which to make a comparison.

  7. Programs To Optimize Simulated Trajectories (POST\\6DPOST)

    NASA Technical Reports Server (NTRS)

    Brauer, Garry L.; Olson, David W.; Stevenson, Robert

    1993-01-01

    Designed for optimizing simulated trajectories, POST is point mass, three degrees-of-freedom program while extended 6DPOST permits rigid-body six degrees-of-freedom models. Handles sophisticated problems such as ascent, orbital maneuvers, and reentry.

  8. The myth of the 90 degrees-angle intramuscular injection.

    PubMed

    Katsma, D L; Katsma, R

    2000-01-01

    This article shows that the textbook 90 degrees-angle requirement for intramuscular injections is unrealistic. Trigonometry demonstrates that an injection given at 72 degrees reaches 95% of the depth of an injection given at 90 degrees. This relation between needle angle and needle depth, previous research into the kinematics of hand motion during an intramuscular injection, and other practical considerations support the proposal for a new, relaxed standard: Intramuscular injections administered at a comfortable angle between 72 degrees and 90 degrees.

  9. Stress Indices and Flexibility Factors for 90-Degree Piping Elbows with Straight Pipe Extensions.

    DTIC Science & Technology

    1982-02-01

    FACTORS FOR 90-DEGREE PIPING ELBOWS WITH STRAIGHT PIPE EXTENS IONS cn by oA. J. Quezon and G. C. Everstine a% APPROVED FOR PUBLIC RELEASE: DISTRIBUTION...FLEXIBILITY FACTORS FOR 90-DEGREE PIPING ELBOWS WITH STRAIGHT PIPE EXTENSIONS 6. PERFORMING OrG. REPORT NUMBER = 7. AUTHOR(e S. CONTRACT OR GRANT NUMBER(e...NOTES 19. KEY WORDS (Continue on reverse elde If neceeeary and Identify by bloc, number) Piping Finite Element Flexibility Factor Elbow NASTRAN Bend

  10. Pershing II Simulation Studies. Debris Dynamics and 2.75 Rocket 6-DOF (Degree of Freedom).

    DTIC Science & Technology

    1983-07-01

    y ^wyy nili ii i...ini n• t • m i •./ i. 1 i• ..• ’J,’<".« r • ’..».’. ^r.*-., y .’ »’.’’•: ’••’irT’.’ y .’ y .’. y .".’. ^, TABLE OF CONTENTS ,w. Page No. I. INTRODUCTION...those of the authors and do not necessarily express or imply policies or positions of the US Army Missile Command. ii wv^ y

  11. Development of flexure based 6-degrees of freedom parallel nano-positioning system with large displacement.

    PubMed

    Kang, Dongwoo; Gweon, Daegab

    2012-03-01

    This paper details the development of a novel flexure jointed precision parallel nano-positioning system in combination with piezo-electric stepping motor for the application of precise optics alignment. The characteristics of the developed system are evaluated in this paper by the simulation and experiments. Based on the precision piezo-electric stepping motor and flexure joints, a high precision motion is obtained. Results of this paper include that of a translation resolution of 15 nm and a rotational resolution of 0.14 arc sec being achieved. In addition, the piezo-electric stepping motors provide a power-off hold characteristic to the system. Meanwhile, the parallel structure provides the high dynamic bandwidth of the lowest resonant frequency of 396.1 Hz. The symmetric structure is advantageous for thermal variation. To increase the motion range of the system, all of flexure joints are designed specially and the coupled workspace of ±2 mm × ±2 mm × ±2 mm × ±2° × ±2° × ±2° is achieved. The overall size of the designed system is Φ350 mm × 120 mm.

  12. Cold injury to a diver's hand after a 90-min dive in 6 degrees C water.

    PubMed

    Laden, Gerard D M; Purdy, Gerard; O'Rielly, Gerard

    2007-05-01

    We present here a case of non-freezing cold injury (NFCI) in a sport scuba diver. There are similarities between the presenting symptoms of NFCI and decompression sickness, e.g., pain and/or altered sensation in an extremity, often reported as numbness. In both conditions patients have been known to describe their lower limbs or feet as feeling woolly. Both conditions are the result of environmental exposure. Additionally, there are no good (high sensitivity and specificity) diagnostic tests for either condition. Diagnosis is made based on patient history, clinical presentation, and examination. NFCI is most frequently seen in military personnel, explorers, and the homeless. When affecting the feet of soldiers it is often referred to as "trench foot." Historically, NFCI has been and continues to be of critical importance in infantry warfare in cold and wet environments. A high priority should be given to prevention of NFCI during military operational planning. With the advent of so-called "technical diving" characterized by going deeper for longer (often in cold water) and adventure tourism, this extremely painful condition is likely to increase in prevalence. NFCI is treated symptomatically.

  13. Telerobotic control of the seven-degree-of-freedom CESAR manipulator

    SciTech Connect

    Babcock, S.M.; Dubey, R.V.; Euler, J.A.; Glassell, R.L.; Kress, R.L.; Hamel, W.R.

    1988-01-01

    The application of a computationally efficient kinematic control scheme for manipulators with redundant degrees of freedom to the unilateral telerobotic control of seven-degree-of-freedom manipulator (CESARM) at the Oak Ridge National Laboratory Center for Engineering Systems Advanced Research is presented. The kinematic control scheme uses a gradient projection optimization method, which eliminates that need to determine the generalized inverse of the Jacobian when solving for joint velocities, given Cartesian end-effector velocities. A six-degree-of-freedom (nonreplica) master controller is used. Performance indices for redundancy resolution are discussed. 5 ref., 6 figs.

  14. Portion of Enhanced 360-degree Gallery Pan

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This is a sub-section of the 'geometrically improved, color enhanced' version of the 360-degree panorama heretofore known as the 'Gallery Pan', the first contiguous, uniform panorama taken by the Imager for Mars Pathfinder (IMP) over the course of Sols 8, 9, and 10. Different regions were imaged at different times over the three Martian days to acquire consistent lighting and shadow conditions for all areas of the panorama.

    The IMP is a stereo imaging system that, in its fully deployed configuration, stands 1.8 meters above the Martian surface, and has a resolution of two millimeters at a range of two meters. In this geometrically improved version of the panorama, distortion due to a 2.5 degree tilt in the IMP camera mast has been removed, effectively flattening the horizon.

    The IMP has color capability provided by 24 selectable filters -- twelve filters per 'eye'. Its red, green, and blue filters were used to take this image. The color was digitally balanced according to the color transmittance capability of a high-resolution TV at the Jet Propulsion Laboratory (JPL), and is dependent on that device. In this color enhanced version of the panorama, detail in surface features are brought out via changes to saturation and intensity, holding the original hue constant. A threshold was applied to avoid changes to the sky.

    At left is a Lander petal and a metallic mast which is a portion of the low-gain antenna. Misregistration in the antenna and other Lander features is due to parallax in the extreme foreground. Another Lander petal is at the right, showing the fully deployed forward ramp.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech). The IMP was developed by the University

  15. Roster of Physics Departments with Enrollment and Degree Data, 2010: Results from the 2010 Survey of Enrollments and Degrees. Focus On

    ERIC Educational Resources Information Center

    Nicholson, Starr; Mulvey, Patrick J.

    2011-01-01

    Academic year 2009-10 produced more physics bachelor's and more physics PhDs than in any other year in US history. The 6,017 physics bachelor's degrees earned in the class of 2010 represent a 65% increase from the class of 1999 eleven years earlier. The 1,558 PhDs in the class of 2010 is up 43% from a recent low 6 years earlier. Non-US citizens…

  16. Increasingly Global: Combining an International Business Degree with a Post-Degree Designation

    ERIC Educational Resources Information Center

    Smith, Rachel; Terry, Andy; Vibhakar, Ashvin

    2006-01-01

    In the increasingly complex and competitive global marketplace, many students seek to gain multiple skills and credentials that can aid them in their career goals. One such career strategy weds a general overarching comprehensive degree with a specific and targeted skill set. This paper provides a viable curriculum path for students who seek…

  17. Pathways to the Doctorate Degree: A Phenomenological Study of African American Women in Doctorate Degree Programs

    ERIC Educational Resources Information Center

    Starks, Luciana Janee'

    2010-01-01

    Increasing the number of advanced degree recipients is more than an educational issue; it is also a key social issue. "A college-educated population results in pivotal benefits to society" (The National Center for Public Policy and Higher Education, 2004, p. 1). Although African Americans have made steady and notable progress in doctorate degree…

  18. Degrees Awarded by Oregon's Degree-Granting Colleges and Universities, 1993-94.

    ERIC Educational Resources Information Center

    Oregon State Dept. of Education, Salem. Office of Educational Policy and Planning.

    This document presents statistical data in summary form on the associate, Bachelor's, Master's, doctoral, and first professional degrees awarded by institutions of higher education in Oregon. These data were obtained from a completions survey which is part of the national Integrated Postsecondary Education Data System (IPEDS). Summary tables are…

  19. Seamless Transfer or Crooked Seams? The Differentiated Outcomes of Associate's Degree Types Completing the Baccalaureate Degree

    ERIC Educational Resources Information Center

    Thomas, John Phillip

    2012-01-01

    In this study academic outcomes for Associate of Applied Science and Associate of Applied Arts degree students who transferred to a large public midwestern research university were examined. A group with transcripted technical credits of 16 hours at transfer were compared and contrasted with a peer group of college-parallel associate's degree…

  20. Astronomy Enrollments and Degrees: Results from the 2007 Survey of Enrollments and Degrees. Focus On

    ERIC Educational Resources Information Center

    Nicholson, Starr; Mulvey, Patrick

    2009-01-01

    The Statistical Research Center of the American Institute of Physics conducts an annual census from October through February of all 75 departments that offer degrees in astronomy in the United States. For the class of 2007, the authors received responses from 73 (97%) of these departments. Estimates were derived and included in the totals for…

  1. Degree of Success? A Review of Delivering BSc Honours Degrees in an FE College

    ERIC Educational Resources Information Center

    Griffiths, Colin; Lloyd, Mary Golding

    2009-01-01

    Widening participation initiatives led by the government encourage non-traditional students to enrol in higher education courses usually offered through a franchising arrangement between a Higher Education Institution (HEI) and a local Further Education Institution (FEI). The focus has been on the development of foundation degrees with most…

  2. Nuclear Engineering Enrollment and Degree Survey: Enrollments - Fall 1972; Degrees Granted - July 1965-June 1972.

    ERIC Educational Resources Information Center

    Chewning, June S.

    The Atomic Energy Commission's survey of nuclear engineering degrees granted during the 1971-72 academic year shows a continuing increase in bachelor's recipients, a slight increase in the number of master's, but a continuing decline in new Ph.D.'s. If the present rate of decline persists, by 1974 the number of new Ph.D.'s in the field will be…

  3. Radiation Protection Enrollments and Degrees. Enrollments--Fall 1973. Degrees Granted July 1965-June 1973.

    ERIC Educational Resources Information Center

    Atomic Energy Commission, Washington, DC. Div. of Labor Relations.

    The demand for radiation protection personnel has increased during the past several years and can be expected to continue to increase for several years to come. This document gives the results of the latest survey of institutions offering degree programs in this field. Such a small segment of the total college enrollment is represented in health…

  4. Differences in STEM Degree Attainment by Region, Ethnicity, and Degree Type

    ERIC Educational Resources Information Center

    Koledoye, Kimberly A.

    2013-01-01

    Purpose: One purpose of this study was to determine the extent to which a difference was present in the STEM degree attainment of all students and particularly of URMs between the 2001 and the 2009 academic year. The second purpose of this study was to determine the extent to which a difference was present in the attainment of STEM associate…

  5. Viability of fungal cultures maintained at -70 degrees C.

    PubMed Central

    Pasarell, L; McGinnis, M R

    1992-01-01

    One thousand four hundred forty-seven clinical and environmental isolates of molds, yeasts, aerobic actinomycetes, and algae belonging to 164 genera (382 taxa) maintained on potato dextrose agar at -70 degrees C for periods ranging from 6 months to 13 years were subcultured and then incubated at 25 degrees C to determine their viabilities. Thirty-three isolates, Alternaria alternata (n = 1), Apophysomyces elegans (n = 1), Bipolaris spicifera (n = 1), Blastomyces dermatitidis (n = 4), Cokeromyces recurvatus (n = 1), Coremiella cubispora (n = 1), Cryptococcus ater (n = 1), Curvularia sp. (n = 1), Exserohilum monoceras (n = 1), Exserohilum pedicillatum (n = 1), Exserohilum rostratum (n = 1), Filobasidium floriforme (n = 1), Madurella mycetomatis (n = 1), Oedocephalum spp. (n = 2), Penicillium marneffei (n = 1), Pseudomicrodochium spp. (n = 4), Saksenaea vasiformis (n = 1), Sporothrix sp. (n = 1), and Mycelia Sterilia (n = 8), did not grow after repeated attempts at subculturing. Neither time in storage nor taxonomic classification was associated with a lack of viability. Storage at low temperature for either short or long periods of time is an excellent method for maintaining most medically important fungi. PMID:1572955

  6. Configuration control of seven-degree-of-freedom arms

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun (Inventor); Long, Mark K. (Inventor); Lee, Thomas S. (Inventor)

    1992-01-01

    A seven degree of freedom robot arm with a six degree of freedom end effector is controlled by a processor employing a 6 by 7 Jacobian matrix for defining location and orientation of the end effector in terms of the rotation angles of the joints, a 1 (or more) by 7 Jacobian matrix for defining 1 (or more) user specified kinematic functions constraining location or movement of selected portions of the arm in terms of the joint angles, the processor combining the two Jacobian matrices to produce an augmented 7 (or more) by 7 Jacobian matrix, the processor effecting control by computing in accordance with forward kinematics from the augmented 7 by 7 Jacobian matrix and from the seven joint angles of the arm a set of seven desired joint angles for transmittal to the joint servo loops of the arm. One of the kinematic functions constraints the orientation of the elbow plane of the arm. Another one of the kinematic functions minimizes a sum of gravitational torques on the joints. Still another kinematic function constrains the location of the arm to perform collision avoidance. Generically, one kinematic function minimizes a sum of selected mechanical parameters of at least some of the joints associated with weighting coefficients which may be changed during arm movement. The mechanical parameters may be velocity errors or gravity torques associated with individual joints.

  7. Configuration control of seven degree of freedom arms

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun (Inventor)

    1995-01-01

    A seven-degree-of-freedom robot arm with a six-degree-of-freedom end effector is controlled by a processor employing a 6-by-7 Jacobian matrix for defining location and orientation of the end effector in terms of the rotation angles of the joints, a 1 (or more)-by-7 Jacobian matrix for defining 1 (or more) user-specified kinematic functions constraining location or movement of selected portions of the arm in terms of the joint angles, the processor combining the two Jacobian matrices to produce an augmented 7 (or more)-by-7 Jacobian matrix, the processor effecting control by computing in accordance with forward kinematics from the augmented 7-by-7 Jacobian matrix and from the seven joint angles of the arm a set of seven desired joint angles for transmittal to the joint servo loops of the arms. One of the kinematic functions constrains the orientation of the elbow plane of the arm. Another one of the kinematic functions minimizing a sum of gravitational torques on the joints. Still another one of the kinematic functions constrains the location of the arm to perform collision avoidance. Generically, one of the kinematic functions minimizes a sum of selected mechanical parameters of at least some of the joints associated with weighting coefficients which may be changed during arm movement. The mechanical parameters may be velocity errors or position errors or gravity torques associated with individual joints.

  8. Portion of 360-degree color panorama

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This image represents the first two tiers of a 360- degree color panorama, taken by the Imager for Mars Pathfinder (IMP). The metallic object at far lower left is a portion of the lander's low-gain antenna. At left, the forward ramp is visible near the larger rocks dubbed Wedge, Flat Top, and Half-Dome. The magenta and yellow strips near the center represent portions of missing data. Rover Sojourner is situated on the soil after its successful deployment on Sol 5. To its immediate left is the rock dubbed 'Barnacle Bill,' and in front of it lies the larger rock dubbed 'Yogi.' Two additional areas of deflated airbags are at the right-center and right of the panorama. The mast and windsocks at far right is the Atmospheric Structure Instrument/Meteorology Package (ASI/MET). Their upward position indicates little air movement. A shadow of the ASI/MET has been cast upon a rock just in front of it, indicating sunlight is coming from the rear right.

    Mars Pathfinder was developed and managed by the Jet Propulsion Laboratory (JPL) for the National Aeronautics and Space Administration. JPL is an operating division of the California Institute of Technology (Caltech). The IMP was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

  9. Area of 360 degree color panorama

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This portion of the 360-degree gallery panorama shows Pathfinder's rear ramp, the rock Barnacle Bill at left, and rover tracks leading up to the large rock Yogi. Rover Sojourner is seen using its Alpha Proton X-Ray Spectrometer (APXS) instrument to study Yogi's composition. Rover tracks and circular patterns in the soil are from Sojourner's soil mechanics experiments, in which varying amounts of pressure were applied to the rover's wheels in order to determine physical properties of the soil. The image was taken by the Imager for Mars Pathfinder (IMP) over sols 8, 9, and 10, using the red, green and blue filters.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

  10. Flutter calculations in three degrees of freedom

    NASA Technical Reports Server (NTRS)

    Theodorsen, Theodore; Garrick, I E

    1942-01-01

    The present paper is a continuation of the general study of flutter published in NACA reports nos. 496 and 685. The paper is mainly devoted to flutter in three degrees of freedom (bending, torsion, and aileron) for which a number of selected cases have been calculated and presented in graphical form. The results are analyzed and discussed with regard to the effects of structural damping, of fractional-span ailerons, and of mass-balancing. The analysis shows that more emphasis should be put on the effect of structural damping and less on mass-balancing. The conclusion is drawn that a definite minimum amount of structural damping, which is usually found to be present, is essential in the calculations for an adequate description of the flutter case. Theoretical flutter predictions are thus brought into closer agreement with the facts of experience. A brief discussion is included of a particular biplane that had experienced flutter at about 200 miles per hour. Some simplifications have been achieved in the method of calculation. (author)

  11. Multiple-degree-of-freedom vehicle

    DOEpatents

    Borenstein, Johann

    1995-01-01

    A multi-degree-of-freedom vehicle employs a compliant linkage to accommodate the need for a variation in the distance between drive wheels or drive systems which are independently steerable and drivable. The subject vehicle is provided with rotary encodes to provide signals representative of the orientation of the steering pivot associated with each such drive wheel or system, and a linear encoder which issues a signal representative of the fluctuations in the distance between the drive elements. The wheels of the vehicle are steered and driven in response to the linear encoder signal, there being provided a controller system for minimizing the fluctuations in the distance. The controller system is a software implementation of a plurality of controllers, operating at the chassis level and at the vehicle level. A trajectory interpolator receives x-displacement, y-displacement, and .theta.-displacement signals and produces to the vehicle level controller trajectory signals corresponding to interpolated control signals. The x-displacement, y-displacement, and .theta.-displacement signals are received from a human operator, via a manipulable joy stick.

  12. Six Degree Freedom Optical Fiber Accelerometer

    NASA Astrophysics Data System (ADS)

    Cazo, Rogerio Moreira; dos Reis Ribeiro, Erik; Nunes, Marcelo Buonocore; Barbosa, Carmem Lucia; de Siqueira Ferreira, Jorge Luis; de Barros Caldas, Tales; dos Santos, Josemir Coelho; de Arruda, Josiel Urbaninho

    2008-10-01

    Linear accelerations measurements are needed in many applications, as industry, military, aircrafts, space navigation, robotics and others. Actually, the most usual solutions to measure linear accelerations are three piezoelectric sensors used in orthogonal mounting, or MEM's sensors chips. Angular accelerations also are interesting to control and stabilize structures, like satellites and servo motors. It is possible to measure angular accelerations in two ways: direct measurement (using special sensors), or indirect measurements (obtaining acceleration of the angular velocity information) [1]. This work intends to present the structural and optical requirements of a six degree freedom opto-mechanical accelerometer based on fiber Bragg grating (FBG). With this sensor, it will be possible the direct measurement of three axial accelerations, and of three angular accelerations, with unlimited rotation angle, using one single proof mass. The FBG's are used as strain sensors and sustaining elements of the proof mass in the structure. Simulations have demonstrated that cross influences of 10 parts per million at worst case are possible. This kind of accelerometer may be used in navigation control, structural monitoring, satellite stabilization, guidance control and harsh environments, for example. The project requirements include the wavelength of FBG's, pre-strain and length of active segment of optical fibers, dimensions, material and structure of inertial proof mass and position of the fibers in the sustaining structure

  13. Interdiffusion and Reaction between Zr and Al Alloys from 425 degrees to 625 degrees C

    SciTech Connect

    J. Dickson; L. Zhou; A. Ewh; M. Fu; D. D. Keiser, Jr.; Y. H. Sohn; A. Paz y Puente

    2014-06-01

    Zirconium has recently garnered attention for use as a diffusion barrier between U–Mo nuclear fuels and Al cladding alloys. Interdiffusion and reactions between Zr and Al, Al-2 wt.% Si, Al-5 wt.% Si or AA6061 were investigated using solid-to-solid diffusion couples annealed in the temperature range of 425 degrees to 625 degrees C. In the binary Al and Zr system, the Al3Zr and Al2Zr phases were identified, and the activation energy for the growth of the Al3Zr phase was determined to be 347 kJ/mol. Negligible diffusional interactions were observed for diffusion couples between Zr vs. Al-2 wt.% Si, Al-5 wt.% Si and AA6061 annealed at or below 475 degrees C. In diffusion couples with the binary Al–Si alloys at 560 degrees C, a significant variation in the development of the phase constituents was observed including the thick t1 (Al5SiZr2) with Si content up to 12 at.%, and thin layers of (Si,Al)2Zr, (Al,Si)3Zr, Al3SiZr2 and Al2Zr phases. The use of AA6061 as a terminal alloy resulted in the development of both T1 (Al5SiZr2) and (Al,Si)3Zr phases with a very thin layer of (Al,Si)2Zr. At 560 degrees C, with increasing Si content in the Al–Si alloy, an increase in the overall rate of diffusional interaction was observed; however, the diffusional interaction of Zr in contact with multicomponent AA6061 with 0.4–0.8 wt.% Si was most rapid.

  14. Improved MPF 360-degree Color Panorama

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This is a more recent 'geometrically improved, color enhanced' version of the 360-degree 'Gallery Pan', the first contiguous, uniform panorama taken by the Imager for Mars (IMP) over the course of Sols 8, 9, and 10. Different regions were imaged at different times over the three Martian days to acquire consistent lighting and shadow conditions for all areas of the panorama. In this version of the panorama, much of the discontinuity that was due to parallax has been corrected, particularly along the lower tiers of the mosaic containing the Lander features. Distortion due to a 2.5 degree tilt in the IMP camera mast has been removed.

    The IMP is a stereo imaging system that, in its fully deployed configuration, stands 1.8 meters above the Martian surface, and has a resolution of two millimeters at a range of two meters. The IMP has color capability provided by 24 selectable filters -- twelve filters per 'eye'. Its red, green, and blue filters were used to take this panorama.

    The three color images were first digitally balanced according to the transmittance capabilities of a specific high-definition TV device at JPL, and then enhanced via changes to saturation and intensity while retaining the hue. A threshold was applied to avoid changes to the sky. An MTF filter was applied to sharpen feature edges.

    At left is a Lander petal and a metallic mast which is a portion of the low-gain antenna. On the horizon the double 'Twin Peaks' are visible, about 1-2 kilometers away. The rock 'Couch' is the dark, curved rock at right of Twin Peaks. Another Lander petal is at left-center, showing the fully deployed forward ramp at far left, and rear ramp at right, which rover Sojourner used to descend to the surface of Mars on July 5. Immediately to the left of the rear ramp is the rock 'Barnacle Bill', which scientists found be andesitic, possibly indicating that it is a volcanic rock (a true andesite) or a physical mixture of particles. Just beyond Barnacle Bill, rover tracks

  15. Color enhanced version of 360-degree panorama

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This is a 'geometrically improved, color enhanced' version of the 360-degree panorama heretofore known as the 'Gallery Pan', the first contiguous, uniform panorama taken by the Imager for Mars Pathfinder (IMP) over the course of Sols 8, 9, and 10. Different regions were imaged at different times over the three Martian days to acquire consistent lighting and shadow conditions for all areas of the panorama.

    The IMP is a stereo imaging system that, in its fully deployed configuration, stands 1.8 meters above the Martian surface, and has a resolution of two millimeters at a range of two meters. In this geometrically improved version of the panorama, distortion due to a 2.5 degree tilt in the IMP camera mast has been removed, effectively flattening the horizon.

    The IMP has color capability provided by 24 selectable filters -- twelve filters per 'eye.' Its red, green, and blue filters were used to take this image. The color was digitally balanced according to the color transmittance capability of a high-resolution TV at the Jet Propulsion Laboratory (JPL), and is dependent on that device. In this color enhanced version of the panorama, detail in surface features are brought out via changes to saturation and intensity, holding the original hue constant. A threshold was applied to avoid changes to the sky.

    At left is a Lander petal and a metallic mast which is a portion of the low-gain antenna. Misregistration in the antenna and other Lander features is due to parallax in the extreme foreground. On the horizon the double 'Twin Peaks' are visible, about 1-2 kilometers away. The rock 'Couch' is the dark, curved rock at right of Twin Peaks. Another Lander petal is at left-center, showing the fully deployed forward ramp at far left, and rear ramp at right, which rover Sojourner used to descend to the surface of Mars on July 5. Immediately to the left of the rear ramp is the rock 'Barnacle Bill', which scientists found to be andesitic, possibly indicating that it is a

  16. 360-degree panorama in 3D

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This 360-degree panorama was taken in stereo by the deployed Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses (red left lens, blue right lens) are necessary to help identify surface detail. All three petals, the perimeter of the deflated airbags, deployed rover Sojourner, forward and backward ramps and prominent surface features are visible, including the double Twin Peaks at the horizon. Sojourner would later investigate the rock Barnacle Bill just to its left in this image, and the larger rock Yogi at its forward right.

    The IMP is a stereo imaging system with color capability provided by 24 selectable filters -- twelve filters per 'eye.' It stands 1.8 meters above the Martian surface, and has a resolution of two millimeters at a range of two meters. Stereoscopic imaging brings exceptional clarity and depth to many of the features in this image, particularly the ridge beyond the far left petal and the large rock Yogi. The curvature and misalignment of several section are due to image parallax.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

    Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right

  17. Optimum design of ninety degree bends

    NASA Technical Reports Server (NTRS)

    Modi, Vijay; Cabuk, Hayri; Huan, Jian-Chun; Quadracci, Richard

    1992-01-01

    An algorithm for the optimum design of an internal flow component to obtain the maximum pressure rise is presented. Maximum pressure rise in a duct with simultaneous turning and diffusion is shown to be related to the control of flow separation on the passage walls. Such a flow is usually associated with downstream conditions that are desirable in turbomachinery and propulsion applications to ensure low loss and stable performance. The algorithm requires the solution of an 'adjoint' problem in addition to the 'direct' equations governing the flow in a body, which in the present analysis are assumed to be the laminar Navier-Stokes equations. The theoretical framework and computational algorithms presented in this study are for the steady Navier-Stokes equations. A procedure is developed for the numerical solution of the adjoint equations. This procedure is coupled with a direct solver in a design iteration loop, that provides a new shape with a higher pressure rise. This procedure is first validated for the design of optimum plane diffusers in two-dimensional flow. The direct Navier-Stokes and the 'adjoint' equations are solved using a finite volume formulation for spatial discretization in an artificial compressibility framework. A simplified version of the above approach is then utilized to design ninety degree diffusing bends. Calculations were carried out for a mean radius ratio at inlet of 2.5 and Reynolds numbers varying from 100 to 500. While at this stage laminar flows is assumed, it is shown that a similar approach can be conceived for turbulent flows.

  18. The Zero-Degree Detector System

    NASA Technical Reports Server (NTRS)

    Adams, James H.; Christl, Mark J.; Howell, Leonard W.; Kouznetsov, Evgueni

    2006-01-01

    We will report on a detector system used for accelerator measurement of nuclear fragmentation cross sections. This system consists of two detector planes, each carrying a ring of 8 detectors. Each detector has 64 pads. These two detector planes are arranged facing each other so that the matching detector pads on each plane form a two element charged particle telescope. Each of these telescopes is capable of determining the elemental identity of nuclear fragments passing through it. The system is used to measure light fragment production in the presence of heavier fragments. We will present a detailed discussion of the 64-pad detector design, the substrate design. The front-end electronics used to read out the signals is based on a custom VLSI chip developed for the Advanced Thin Ionization Calorimeter experiment which has been flown successfully twice in Antarctica. Each of these chips has 16 channels and each channel consists of a charge-sensitive preamplifier followed by a shaping amplifier and a track-and-hold circuit. The track-and-hold circuits are connected via a multiplexer to an output line driver. This allows the held signals to be presented, one-by-one via a common data line to a analog-to-digital converter. Because the output line driver can be placed in a high input impedance state when not in use, it is possible to daisy-change many chips on the same common data line. The front-end electronics and data readout scheme will be discussed in detail. The Zero Degree Detector has been used in several accelerator experiments conducted at the NASA Space Radiation Laboratory and the Alternating Gradient Synchrotron at Brookhaven National Laboratory as well as at the HIMAC accelerator in Japan. We will show examples of data taken at these accelerator runs to demonstrate how the system works.

  19. A degree of success? Messages from the new social work degree in England for nurse education.

    PubMed

    Moriarty, Jo; Manthorpe, Jill; Stevens, Martin; Hussein, Shereen; Macintyre, Gillian; Orme, Joan; Green Lister, Pam; Sharpe, Endellion; Crisp, Beth

    2010-07-01

    In September 2008 the Nursing and Midwifery Council (NMC) approved plans to change pre-registration nursing education in England to an all-graduate qualification in 2015. In 2001 the Department of Health announced a similar decision for social work qualifying education and the first graduate-only qualifying programmes began in 2003-2004. This article presents findings from a national in-depth evaluation of the social work degree in England and describes ways in which efforts have been made to improve the quality of social workers, raise the status of the profession and link practice and theory as part of the transformation to a degree level qualification. Messages for nurse educators are drawn in the light of the professions' commonalities.

  20. Survival of Escherichia coli O157:H7 in ground-beef patties during storage at 2, -2, 15 and then -2 degrees C, and -20 degrees C.

    PubMed

    Ansay, S E; Darling, K A; Kaspar, C W

    1999-11-01

    The survival of Escherichia coli O157:H7 and of a nonpathogenic control strain of E. coli was monitored in raw ground beef that was stored at 2 degrees C for 4 weeks, -2 degrees C for 4 weeks, 15 degrees C for 4 h and then -2 degrees C for 4 weeks, and -20 degrees C. Irradiated ground beef was inoculated with one E. coli control strain or with a four-strain cocktail of E. coli O157:H7 (ca. 10(5) CFU/g), formed into patties (30 to 45 g), and stored at the appropriate temperature. The numbers of the E. coli control strain decreased by 1.4 log 10 CFU/g, and pathogen numbers declined 1.9 log 10 CFU/g when patties were stored for 4 weeks at 20 degrees C. When patties were stored at -2 degrees C for 4 weeks, the numbers of the E. coli control strain and the serotype O157:H7 strains decreased 2.8 and 1.5 log 10 CFU/g, respectively. Patties stored at 15 degrees C for 4 h prior to storage at -2 degrees C for 4 weeks resulted in 1.6 and 2.7 log 10-CFU/g reduction in the numbers of E. coli and E. coli O157:H7, respectively. Storage of retail ground beef at 15 degrees C for 4 h (tempering) did not result in increased numbers of colony forming units per gram, as determined with violet red bile, MRS lactobacilli, and plate-count agars. Frozen storage (-20 degrees C) of ground-beef patties that had been inoculated with a single strain of E. coli resulted in approximately a 1 to 2 log 10-CFU/g reduction in the numbers of the control strain and individual serotype O157:H7 strains after 1 year. There was no significant difference between the survival of the control strain and the O157:H7 strains, nor was there a difference between O157:H7 strains. These data demonstrate that tempering of ground-beef patties prior to low-temperature storage accelerated the decline in the numbers of E. coli O157:H7.