WorldWideScience

Sample records for tilt bed rest

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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 (pdifferent in cosmonauts and in subjects participating in the head down tilted bed rest study (170± 29% (Mean± SEM) vs. 57± 7%, respectively; presponse to combined effects of a reduced plasma volume and an increased vascular capacity in flight.

  6. Analysis of Arterial Mechanics During Head-Down-Tilt Bed Rest

    Science.gov (United States)

    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).

  7. Space headache on Earth: head-down-tilted bed rest studies simulating outer-space microgravity.

    Science.gov (United States)

    van Oosterhout, W P J; Terwindt, G M; Vein, A A; Ferrari, M D

    2015-04-01

    Headache is a common symptom during space travel, both isolated and as part of space motion syndrome. Head-down-tilted bed rest (HDTBR) studies are used to simulate outer space microgravity on Earth, and allow countermeasure interventions such as artificial gravity and training protocols, aimed at restoring microgravity-induced physiological changes. The objectives of this article are to assess headache incidence and characteristics during HDTBR, and to evaluate the effects of countermeasures. In a randomized cross-over design by the European Space Agency (ESA), 22 healthy male subjects, without primary headache history, underwent three periods of -6-degree HDTBR. In two of these episodes countermeasure protocols were added, with either centrifugation or aerobic exercise training protocols. Headache occurrence and characteristics were daily assessed using a specially designed questionnaire. In total 14/22 (63.6%) subjects reported a headache during ≥1 of the three HDTBR periods, in 12/14 (85.7%) non-specific, and two of 14 (14.4%) migraine. The occurrence of headache did not differ between HDTBR with and without countermeasures: 12/22 (54.5%) subjects vs. eight of 22 (36.4%) subjects; p = 0.20; 13/109 (11.9%) headache days vs. 36/213 (16.9%) headache days; p = 0.24). During countermeasures headaches were, however, more often mild (p = 0.03) and had fewer associated symptoms (p = 0.008). Simulated microgravity during HDTBR induces headache episodes, mostly on the first day. Countermeasures are useful in reducing headache severity and associated symptoms. Reversible, microgravity-induced cephalic fluid shift may cause headache, also on Earth. HDTBR can be used to study space headache on Earth. © International Headache Society 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  16. Changes in the levels of mannan-binding lectin and ficolins during head-down tilted bed rest.

    Science.gov (United States)

    Kelsen, Jens; Sandahl, Thomas D; Storm, Line; Frings-Meuthen, Petra; Dahlerup, Jens F; Thiel, Steffen

    2014-08-01

    Spaceflight studies and ground-based analogues of microgravity indicate a weakening of human immunity. Mannan-binding lectin (MBL) and H-, L-, and M-ficolin together constitute the lectin pathway and mediate the clearance of pathogens through complement activation. We hypothesized that simulated microgravity may weaken human innate immune functions and studied the impact of 6° head-down tilted bed rest (HDT) for 21 d on MBL and ficolin levels. Within a 6-mo period, seven men underwent two periods of HDT. Blood samples were analyzed for MBL, H-, L-, and M-ficolin, mannose-binding lectin-associated protein of 44 kDa (MAp44), and collectin liver 1 (CL-L1) by time-resolved immunofluorometric assays (TRIFMA). We observed well-defined individual preintervention levels of MBL and ficolins. Remarkably similar intraindividual changes occurred for MBL and MBL levels decreased (mean 282 ng · ml⁻¹) in the recovery phase. Conversely, CL-L1, a protein with MBL-like properties, increased (mean 102 ng · ml⁻¹) during the recovery phase. M-ficolin increased (mean 79 ng · ml⁻¹) within the first 2 d of HDT, followed by a decrease (mean 112 ng · ml⁻¹) during the recovery phase. L-ficolin increased (mean 304 ng · ml⁻¹) during HDT, while H-ficolin was essentially unaffected. MAp44, a down-regulator of the lectin pathway, decreased initially (mean 78 ng · ml⁻¹) in the recovery phase followed by an increase (mean 131 ng · ml⁻¹). Alterations in MBL and ficolin levels were modest and with our current knowledge do not lead to overt immunodeficiency. Pronounced changes occurred when the subjects resumed the upright position. In selected individuals, these changes appear to be a conserved response to HDT.

  17. 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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

  19. Decreasing ventromedial prefrontal cortex deactivation in risky decision making after simulated microgravity: Effects of -6 degree head-down tilt bed rest

    Directory of Open Access Journals (Sweden)

    Li-Lin eRao

    2014-05-01

    Full Text Available 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.

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

    Science.gov (United States)

    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

  1. A combination of whey protein and potassium bicarbonate supplements during head-down-tilt bed rest: Presentation of a multidisciplinary randomized controlled trial (MEP study)

    Science.gov (United States)

    Buehlmeier, Judith; Mulder, Edwin; Noppe, Alexandra; Frings-Meuthen, Petra; Angerer, Oliver; Rudwill, Floriane; Biolo, Gianni; Smith, Scott M.; Blanc, Stéphane; Heer, Martina

    2014-02-01

    Inactivity, as it appears during space flight and in bed rest, induces reduction of lean body and bone mass, glucose intolerance, and weakening of the cardiovascular system. Increased protein intake, whey protein in particular, has been proposed to counteract some of these effects, but has also been associated with negative effects on bone, likely caused by a correspondingly high ratio of acid to alkali precursors in the diet.

  2. Physiology Of Prolonged Bed Rest

    Science.gov (United States)

    Greenleaf, John E.

    1991-01-01

    Report describes physiological effects of prolonged bed rest. Rest for periods of 24 hours or longer deconditions body to some extent; healing proceeds simultaneously with deconditioning. Report provides details on shifts in fluid electrolytes and loss of lean body mass, which comprises everything in body besides fat - that is, water, muscle, and bone. Based on published research.

  3. Exercise countermeasures for bed-rest deconditioning

    Science.gov (United States)

    Greenleaf, John (Editor)

    1993-01-01

    The purpose for this 30-day bed rest study was to investigate the effects of short-term, high intensity isotonic and isokinetic exercise training on maintenance of working capacity (peak oxygen uptake), muscular strength and endurance, and on orthostatic tolerance, posture and gait. Other data were collected on muscle atrophy, bone mineralization and density, endocrine analyses concerning vasoactivity and fluid-electrolyte balance, muscle intermediary metabolism, and on performance and mood of the subjects. It was concluded that: The subjects maintained a relatively stable mood, high morale, and high esprit de corps throughout the study. Performance improved in nearly all tests in almost all the subjects. Isotonic training, as opposed to isokinetic exercise training, was associated more with decreasing levels of psychological tension, concentration, and motivation; and improvement in the quality of sleep. Working capacity (peak oxygen uptake) was maintained during bed rest with isotonic exercise training; it was not maintained with isokinetic or no exercise training. In general, there was no significant decrease in strength or endurance of arm or leg muscles during bed rest, in spite of some reduction in muscle size (atrophy) of some leg muscles. There was no effect of isotonic exercise training on orthostasis, since tilt-table tolerance was reduced similarly in all three groups following bed rest. Bed rest resulted in significant decreases of postural stability and self-selected step length, stride length, and walking velocity, which were not influenced by either exercise training regimen. Most pre-bed rest responses were restored by the fourth day of recovery.

  4. Clinical physiology of bed rest

    Science.gov (United States)

    Greenleaf, John E.

    1993-01-01

    Maintenance of optimal health in humans requires the proper balance between exercise, rest, and sleep as well as time in the upright position. About one-third of a lifetime is spent sleeping; and it is no coincidence that sleeping is performed in the horizontal position, the position in which gravitational influence on the body is minimal. Although enforced bed rest is necessary for the treatment of some ailments, in some cases it has probably been used unwisely. In addition to the lower hydrostatic pressure with the normally dependent regions of the cardiovascular system, body fuid compartments during bed rest in the horizontal body position, and virtual elimination of compression on the long bones of the skeletal system during bed rest (hypogravia), there is often reduction in energy metabolism due to the relative confinement (hypodynamia) and alteration of ambulatory circadian variations in metabolism, body temperature, and many hormonal systems. If patients are also moved to unfamiliar surroundings, they probably experience some feelings of anxiety and some sociopsychological problems. Adaptive physiological responses during bed rest are normal for that environment. They are attempts by the body to reduce unnecessary energy expenditure, to optimize its function, and to enhance its survival potential. Many of the deconditioning responses begin within the first day or two of bed rest; these early responses have prompted physicians to insist upon early resumption of the upright posture and ambulation of bedridden patients.

  5. The NASA Bed Rest Project

    Science.gov (United States)

    Rhodes, Bradley; Meck, Janice

    2005-01-01

    NASA s National Vision for Space Exploration includes human travel beyond low earth orbit and the ultimate safe return of the crews. Crucial to fulfilling the vision is the successful and timely development of countermeasures for the adverse physiological effects on human systems caused by long term exposure to the microgravity environment. Limited access to in-flight resources for the foreseeable future increases NASA s reliance on ground-based analogs to simulate these effects of microgravity. The primary analog for human based research will be head-down bed rest. By this approach NASA will be able to evaluate countermeasures in large sample sizes, perform preliminary evaluations of proposed in-flight protocols and assess the utility of individual or combined strategies before flight resources are requested. In response to this critical need, NASA has created the Bed Rest Project at the Johnson Space Center. The Project establishes the infrastructure and processes to provide a long term capability for standardized domestic bed rest studies and countermeasure development. The Bed Rest Project design takes a comprehensive, interdisciplinary, integrated approach that reduces the resource overhead of one investigator for one campaign. In addition to integrating studies operationally relevant for exploration, the Project addresses other new Vision objectives, namely: 1) interagency cooperation with the NIH allows for Clinical Research Center (CRC) facility sharing to the benefit of both agencies, 2) collaboration with our International Partners expands countermeasure development opportunities for foreign and domestic investigators as well as promotes consistency in approach and results, 3) to the greatest degree possible, the Project also advances research by clinicians and academia alike to encourage return to earth benefits. This paper will describe the Project s top level goals, organization and relationship to other Exploration Vision Projects, implementation

  6. Gradient Compression Stockings may Prevent Recovery after Bed Rest Deconditioning

    Science.gov (United States)

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

    2011-01-01

    Introduction: Astronauts continue to wear a compression garment during and immediately after landing to prevent orthostatic intolerance (OI). We recently developed a custom-fitted, 3-piece garment that consists of thigh-high stockings with biker-style shorts that provides continuous, gradient compression: 55 mmHg at the ankle that decreases to approximately 20 mmHg at the top of the leg and 15 mmHg over the abdomen. This garment has been shown to be effective in preventing symptoms of OI during a short stand test after Space Shuttle missions, but symptoms may persist for several days after a long-duration mission in some astronauts. The purpose of this study was to confirm the effectiveness of wearing these elastic, gradient compression garments during orthostatic testing after 2 weeks of 6 degree head-down tilt bed rest as a model of spaceflight and to determine whether they would impact recovery after bed rest. Methods: Eight (5 treatment, 3 control) of 16 subjects have completed this study to-date. All subjects wore the 3-piece garment from waking until tilt testing (3 h) as a simulation of the timeline for astronauts on landing day (BR+0). Control subjects removed the garment after the tilt test. Treatment subjects wore the garment for the remainder of the day and wore lower compression thigh-high only garments on the day after bed rest (BR+1). Blood pressure, heart rate, and stroke volume responses to a 15-min 80 degree head-up tilt test were determined before 2 weeks of 6 degree head-down tilt, and on BR+0 and BR+1. Plasma volume (PV) was measured before each of these test sessions. Data are mean SE. Results: Compression garments prevented signs of OI on BR+0; all subjects in both groups completed the full 15-min test. Heart rate responses to tilt were lower on BR+0 than all other test days. Control subjects demonstrated a marginal PV decrease after bed rest, but showed typical recovery the day after bed rest (BR+0: 2.32 plus or minus 0.15 L to BR+1: 2

  7. The Effects of Long Duration Bed Rest on Functional Mobility and Balance: Relationship to Resting State Motor Cortex Connectivity

    Science.gov (United States)

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

    2014-01-01

    NASA offers researchers from a variety of backgrounds the opportunity to study bed rest as an experimental analog for space flight. Extended exposure to a head-down tilt position during long duration bed rest can resemble many of the effects of a low-gravity environment such as reduced sensory inputs, body unloading and increased cephalic fluid distribution. The aim of our study is to a) identify changes in brain function that occur with prolonged bed rest and characterize their recovery time course; b) assess whether and how these changes impact behavioral and neurocognitive performance. Thus far, we completed data collection from six participants that include task based and resting state fMRI. The data have been acquired through the bed rest facility located at the University of Texas Medical Branch (Galveston, TX). Subjects remained in bed with their heads tilted down 6 degrees below their feet for 70 consecutive days. Behavioral measures and neuroimaging assessments were obtained at seven time points: a) 7 and 12 days before bed rest; b) 7, 30, and 65 days during bed rest; and c) 7 and 12 days after bed rest. Functional connectivity magnetic resonance imaging (FcMRI) analysis was performed to assess the connectivity of motor cortex in and out of bed rest. We found a decrease in motor cortex connectivity with vestibular cortex and the cerebellum from pre bed rest to in bed rest. We also used a battery of behavioral measures including the functional mobility test and computerized dynamic posturography collected before and after bed rest. We will report the preliminary results of analyses relating brain and behavior changes. Furthermore, we will also report the preliminary results of a spatial working memory task and vestibular stimulation during in and out of bed rest.

  8. Feasibility Study of a Lunar Analog Bed Rest Model

    Science.gov (United States)

    Cromwell, Ronita L.; Platts, Steven H.; Yarbough, Patrice; Buccello-Stout, Regina

    2010-01-01

    The purpose of this study was to determine the feasibility of using a 9.5deg head-up tilt bed rest model to simulate the effects of the 1/6 g load to the human body that exists on the lunar surface. The lunar analog bed rest model utilized a modified hospital bed. The modifications included mounting the mattress on a sled that rolled on bearings to provide freedom of movement. The weight of the sled was off-loaded using a counterweight system to insure that 1/6 body weight was applied along the long axis (z-axis) of the body. Force was verified through use of a force plate mounted at the foot of the bed. A seating assembly was added to the bed to permit periods of sitting. Subjects alternated between standing and sitting positions throughout the day. A total of 35% of the day was spent in the standing position and 65% was spent sitting. In an effort to achieve physiologic fluid shifts expected for a 1/6 G environment, subjects wore compression stockings and performed unloaded foot and ankle exercises. Eight subjects (3 females and 5 males) participated in this study. Subjects spent 13 days in the pre-bed rest phase, 6 days in bed rest and 3 days post bed rest. Subjects consumed a standardized diet throughout the study. To determine feasibility, measures of subject comfort, force and plasma volume were collected. Subject comfort was assessed using a Likert scale. Subjects were asked to assess level of comfort (0-100) for 11 body regions and provide an overall rating. Results indicated minimal to no discomfort as most subjects reported scores of zero. Force measures were performed for each standing position and were validated against subject s calculated 1/6 body weight (r(sup 2) = 0.993). The carbon monoxide rebreathing technique was used to assess plasma volume during pre-bed rest and on the last day of bed rest. Plasma volume results indicated a significant decrease (p = 0.001) from pre to post bed rest values. Subjects lost on average 8.3% (sd = 6.1%) during the

  9. A novel lunar bed rest analogue.

    Science.gov (United States)

    Cavanagh, Peter R; Rice, Andrea J; Licata, Angelo A; Kuklis, Matthew M; Novotny, Sara C; Genc, Kerim O; Englehaupt, Ricki K; Hanson, Andrea M

    2013-11-01

    Humans will eventually return to the Moon and thus there is a need for a ground-based analogue to enable the study of physiological adaptations to lunar gravity. An important unanswered question is whether or not living on the lunar surface will provide adequate loading of the musculoskeletal system to prevent or attenuate the bone loss that is seen in microgravity. Previous simulations have involved tilting subjects to an approximately 9.5 degrees angle to achieve a lunar gravity component parallel to the long-axis of the body. However, subjects in these earlier simulations were not weight-bearing, and thus these protocols did not provide an analogue for load on the musculoskeletal system. We present a novel analogue which includes the capability to simulate standing and sitting in a lunar loading environment. A bed oriented at a 9.5 degrees angle was mounted on six linear bearings and was free to travel with one degree of freedom along rails. This allowed approximately 1/6 body weight loading of the feet during standing. "Lunar" sitting was also successfully simulated. A feasibility study demonstrated that the analogue was tolerated by subjects for 6 d of continuous bed rest and that the reaction forces at the feet during periods of standing were a reasonable simulation of lunar standing. During the 6 d, mean change in the volume of the quadriceps muscles was -1.6% +/- 1.7%. The proposed analogue would appear to be an acceptable simulation of lunar gravity and deserves further exploration in studies of longer duration.

  10. The Physiology of Bed Rest. Chapter 39

    Science.gov (United States)

    Fortney, Suzanne M.; Schneider, Victor S.; Greenleaf, John E.

    1996-01-01

    Prolonged rest in bed has been utilized by physicians and other health-care workers to immobilize and confine patients for rehabilitation and restoration of health since time immemorial. The sitting or horizontal position is sought by the body to relieve the strain of the upright or vertical postures, for example during syncopal situations, bone fractures, muscle injuries, fatigue, and probably also to reduce energy expenditure. Most health-care personnel are aware that adaptive responses occurring during bed rest proceed concomitantly with the healing process; signs and symptoms associated with the former should be differentiated from those of the latter. Not all illnesses and infirmities benefit from prolonged bed rest. Considerations in prescribing bed rest for patients-including duration, body position, mode and duration of exercise, light-dark cycles, temperature, and humidity-have not been investigated adequately. More recently, adaptive physiological responses have been measured in normal, healthy subjects in the horizontal or slightly head-down postures during prolonged bed rest as analogs for the adaptive responses of astronauts exposed to the microgravity environment of outer and bed-rest research.

  11. Changes in markers of bone formation and resorption in a bed rest model of weightlessness

    Science.gov (United States)

    Lueken, S. A.; Arnaud, S. B.; Taylor, A. K.; Baylink, D. J.

    1993-01-01

    To study the mechanism of bone loss in physical unloading, we examined indices of bone formation and bone resorption in the serum and urine of eight healthy men during a 7 day -6 degrees head-down tilt bed rest. Prompt increases in markers of resorption--pyridinoline (PD), deoxypyridinoline (DPD), and hydroxyproline (Hyp)/g creatinine--during the first few days of inactivity were paralleled by tartrate-resistant acid phosphatase (TRAP) with significant increases in all these markers by day 4 of bed rest. An index of formation, skeletal alkaline phosphatase (SALP), did not change during bed rest and showed a moderate 15% increase 1 week after reambulation. In contrast to SALP, serum osteocalcin (OC) began increasing the day preceding the increase in Hyp, remained elevated for the duration of the bed rest, and returned to pre-bed rest values within 5 days of reambulation. Similarly, DPD increased significantly at the onset of bed rest, remained elevated for the duration of bed rest, and returned to pre-bed rest levels upon reambulation. On the other hand, the other three indices of resorption, Hyp, PD, and TRAP, remained elevated for 2 weeks after reambulation. The most sensitive indices of the levels of physical activity proved to be the noncollagenous protein, OC, and the collagen crosslinker, DPD. The bed rest values of both these markers were significantly elevated compared to both the pre-bed rest values and the post-bed rest values. The sequence of changes in the circulating markers of bone metabolism indicated that increases in serum OC are the earliest responses of bone to head-down tilt bed rest.

  12. Cardiac atrophy after bed rest and spaceflight

    Science.gov (United States)

    Perhonen, M. A.; Franco, F.; Lane, L. D.; Buckey, J. C.; Blomqvist, C. G.; Zerwekh, J. E.; Peshock, R. M.; Weatherall, P. T.; Levine, B. D.

    2001-01-01

    Cardiac muscle adapts well to changes in loading conditions. For example, left ventricular (LV) hypertrophy may be induced physiologically (via exercise training) or pathologically (via hypertension or valvular heart disease). If hypertension is treated, LV hypertrophy regresses, suggesting a sensitivity to LV work. However, whether physical inactivity in nonathletic populations causes adaptive changes in LV mass or even frank atrophy is not clear. We exposed previously sedentary men to 6 (n = 5) and 12 (n = 3) wk of horizontal bed rest. LV and right ventricular (RV) mass and end-diastolic volume were measured using cine magnetic resonance imaging (MRI) at 2, 6, and 12 wk of bed rest; five healthy men were also studied before and after at least 6 wk of routine daily activities as controls. In addition, four astronauts were exposed to the complete elimination of hydrostatic gradients during a spaceflight of 10 days. During bed rest, LV mass decreased by 8.0 +/- 2.2% (P = 0.005) after 6 wk with an additional atrophy of 7.6 +/- 2.3% in the subjects who remained in bed for 12 wk; there was no change in LV mass for the control subjects (153.0 +/- 12.2 vs. 153.4 +/- 12.1 g, P = 0.81). Mean wall thickness decreased (4 +/- 2.5%, P = 0.01) after 6 wk of bed rest associated with the decrease in LV mass, suggesting a physiological remodeling with respect to altered load. LV end-diastolic volume decreased by 14 +/- 1.7% (P = 0.002) after 2 wk of bed rest and changed minimally thereafter. After 6 wk of bed rest, RV free wall mass decreased by 10 +/- 2.7% (P = 0.06) and RV end-diastolic volume by 16 +/- 7.9% (P = 0.06). After spaceflight, LV mass decreased by 12 +/- 6.9% (P = 0.07). In conclusion, cardiac atrophy occurs during prolonged (6 wk) horizontal bed rest and may also occur after short-term spaceflight. We suggest that cardiac atrophy is due to a physiological adaptation to reduced myocardial load and work in real or simulated microgravity and demonstrates the plasticity

  13. Executive function on the 16-day of bed rest in young healthy men

    Science.gov (United States)

    Ishizaki, Yuko; Fukuoka, Hideoki; Tanaka, Hidetaka; Ishizaki, Tatsuro; Fujii, Yuri; Hattori-Uchida, Yuko; Nakamura, Minako; Ohkawa, Kaoru; Kobayashi, Hodaka; Taniuchi, Shoichiro; Kaneko, Kazunari

    2009-05-01

    Microgravity due to prolonged bed rest may cause changes in cerebral circulation, which is related to brain function. We evaluate the effect of simulated microgravity due to a 6° head-down tilt bed rest experiment on executive function among 12 healthy young men. Four kinds of psychoneurological tests—the table tapping test, the trail making test, the pointing test and losing at rock-paper-scissors—were performed on the baseline and on day 16 of the experiment. There was no significant difference in the results between the baseline and day 16 on all tests, which indicated that executive function was not impaired by the 16-day 6° head-down tilting bed rest. However, we cannot conclude that microgravity did not affect executive function because of the possible contribution of the following factors: (1) the timing of tests, (2) the learning effect, or (3) changes in psychophysiology that were too small to affect higher brain function.

  14. The Effects of Long Duration Bed Rest on Brain Functional Connectivity and Sensorimotor Functioning

    Science.gov (United States)

    Cassady, K.; Koppelmans, V.; De Dios, Y.; Stepanyan, V.; Szecsy, D.; Gadd, N.; Wood, S.; Reuter-Lorenz, P.; Castenada, R. Riascos; Kofman, I.; hide

    2016-01-01

    Long duration spaceflight has been associated with detrimental alterations in human sensorimotor functioning. Prolonged exposure to a head-down tilt (HDT) position during long duration bed rest can resemble several effects of the microgravity environment such as reduced sensory inputs, body unloading and increased cephalic fluid distribution. The question of whether microgravity affects other central nervous system functions such as brain functional connectivity and its relationship with behavior is largely unknown, but of importance to the health and performance of astronauts both during and post-flight. In the present study, we investigate the effects of prolonged exposure to HDT bed rest on resting state brain functional connectivity and its association with behavioral changes in 17 male participants. To validate that our findings were not due to confounding factors such as time or task practice, we also acquired resting state functional magnetic resonance imaging (rs-fMRI) and behavioral measurements from 14 normative control participants at four time points. Bed rest participants remained in bed with their heads tilted down six degrees below their feet for 70 consecutive days. Rs-fMRI and behavioral data were obtained at seven time points averaging around: 12 and 8 days prior to bed rest; 7, 50, and 70 days during bed rest; and 8 and 12 days after bed rest. 70 days of HDT bed rest resulted in significant increases in functional connectivity during bed rest followed by a reversal of changes in the post bed rest recovery period between motor cortical and somatosensory areas of the brain. In contrast, decreases in connectivity were observed between temporoparietal regions. Furthermore, post-hoc correlation analyses revealed a significant relationship between motor-somatosensory network connectivity and standing balance performance changes; participants that exhibited the greatest increases in connectivity strength showed the least deterioration in postural

  15. "Therapeutic" bed rest in pregnancy: unethical and unsupported by data.

    Science.gov (United States)

    McCall, Christina A; Grimes, David A; Lyerly, Anne Drapkin

    2013-06-01

    "Therapeutic" bed rest continues to be used widely, despite evidence of no benefit and known harms. In this commentary, we summarize the Cochrane reviews of bed rest and propose an ethical argument for discontinuing this practice. Cochrane systematic reviews do not support "therapeutic" bed rest for threatened abortion, hypertension, preeclampsia, preterm birth, multiple gestations, or impaired fetal growth. This assessment has been echoed in other comprehensive reviews. Prescribing bed rest is inconsistent with the ethical principles of autonomy, beneficence, and justice. Hence, if bed rest is to be used, it should be only within a formal clinical trial.

  16. Petechiae: reproducible pattern of distribution and increased appearance after bed rest.

    Science.gov (United States)

    Ganse, Bergita; Limper, Ulrich; Bühlmeier, Judith; Rittweger, Jörn

    2013-08-01

    Exposure to acceleration can cause petechial hemorrhages, called G measles. Petechiae usually start to develop between 5 and 9 G with a high interindividual variance. Centrifuge training delays the onset to higher G levels. One might expect onset at lower G levels after bed rest; however, there is no evidence in the literature. A case of petechiae formation after bed rest is presented here. Orthostatic tolerance was tested using a tilt table and lower body negative pressure before and after bed rest in both campaigns of a 2 x 21-d bed rest study with 6 degrees head-down tilt. A 42-yr-old male Caucasian without any history of thrombosis, venous disease, hemorrhage, or petechiae, and with a negative thrombophilia screening, took part in the bed rest study as 1 out of 10 subjects. He was the only one to develop petechiae during the orthostatic tests after, but not before, bed rest in both campaigns. Petechiae were distributed throughout the lower legs and most pronounced at the shin in a stocking-like fashion, surprisingly reoccurring in an identical pattern of distribution. Petechiae appeared slowly over minutes during hyperemia. This case indicates that prolonged bed rest decreases the threshold for petechiae formation. A reproducible distribution pattern suggests that factors predisposing to petechiae formation keep their local distribution over time (possibly due to local vessel structures). Mechanisms of adaptation and interindividual variance are unclear. Findings are of clinical relevance as such cases might occur after prolonged bed rest in patients without need of expensive testing.

  17. The Effects of Long Duration Bed Rest as a Spaceflight Analogue on Resting State Sensorimotor Network Functional Connectivity and Neurocognitive Performance

    Science.gov (United States)

    Cassady, K.; Koppelmans, V.; Yuan, P.; Cooke, K.; De Dios, Y.; Stepanyan, V.; Szecsy, D.; Gadd, N.; Wood, S.; Reuter-Lorenz, P.; hide

    2015-01-01

    Long duration spaceflight has been associated with detrimental alterations in human sensorimotor systems and neurocognitive performance. Prolonged exposure to a head-down tilt position during long duration bed rest can resemble several effects of the microgravity environment such as reduced sensory inputs, body unloading and increased cephalic fluid distribution. The question of whether microgravity affects other central nervous system functions such as brain functional connectivity and its relationship with neurocognitive performance is largely unknown, but of potential importance to the health and performance of astronauts both during and post-flight. The aims of the present study are 1) to identify changes in sensorimotor resting state functional connectivity that occur with extended bed rest exposure, and to characterize their recovery time course; 2) to evaluate how these neural changes correlate with neurocognitive performance. Resting-state functional magnetic resonance imaging (rsfMRI) data were collected from 17 male participants. The data were acquired through the NASA bed rest facility, located at the University of Texas Medical Branch (Galveston, TX). Participants remained in bed with their heads tilted down six degrees below their feet for 70 consecutive days. RsfMRI data were obtained at seven time points: 7 and 12 days before bed rest; 7, 50, and 65 days during bed rest; and 7 and 12 days after bed rest. Functional connectivity magnetic resonance imaging (fcMRI) analysis was performed to measure the connectivity of sensorimotor networks in the brain before, during, and post-bed rest. We found a decrease in left putamen connectivity with the pre- and post-central gyri from pre bed rest to the last day in bed rest. In addition, vestibular cortex connectivity with the posterior cingulate cortex decreased from pre to post bed rest. Furthermore, connectivity between cerebellar right superior posterior fissure and other cerebellar regions decreased from

  18. Exercise Effects on the Course of Gray Matter Changes Over 70 Days of Bed Rest

    Science.gov (United States)

    Koppelmans, V.; Ploutz-Snyder, L.; 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 affects posture control, locomotion, and manual control. The microgravity environment is an important causal factor for spaceflight induced sensorimotor changes through direct effects on peripheral changes that result from reduced vestibular stimulation and body unloading. Effects of microgravity on sensorimotor function have been investigated on earth using bed rest studies. Long duration bed rest serves as a space-flight analogue because it mimics microgravity in body unloading and bodily fluid shifts. It has been hypothesized that the cephalad fluid shift that has been observed in microgravity could potentially affect central nervous system function and structure, and thereby indirectly affect sensorimotor or cognitive functioning. Preliminary results of one of our ongoing studies indeed showed that 70 days of long duration head down-tilt bed rest results in focal changes in gray matter volume from pre-bed rest to various time points during bed rest. These gray matter changes that could reflect fluid shifts as well as neuroplasticity were related to decrements in motor skills such as maintenance of equilibrium. In consideration of the health and performance of crewmembers both inand post-flight we are currently conducting a study that investigates the potential preventive effects of exercise on gray matter and motor performance changes that we observed over the course of bed rest. Numerous studies have shown beneficial effects of aerobic exercise on brain structure and cognitive performance in healthy and demented subjects over a large age range. We therefore hypothesized that an exercise intervention in bed rest could potentially mitigate or prevent the effects of bed rest on the central nervous system. Here we present preliminary outcomes of our study.

  19. Comparison of Ocular Outcomes in Two 14-Day Bed Rest Studies

    Science.gov (United States)

    Cromwell, R. L.; Zanello, S. B.; Yarbough, P. O.; Taibbi, G.; Vizzeri, G.

    2011-01-01

    Reports of astronauts visual changes raised concern about ocular health during long-duration spaceflight. Some of these findings included hyperopic shifts, choroidal folds, optic disc edema, retinal nerve fiber layer (RNFL) thickening, and cotton wool spots. While the etiology remains unknown, hypotheses speculate that hypertension in the brain caused by cephalad fluid shifts during spaceflight is a possible mechanism for these ocular changes. Head-down tilt (HDT) bed rest is a spaceflight analog that induces cephalad fluid shifts. In addition, previous studies of the HDT position demonstrated body fluid shifts associated with changes in intraocular pressure (IOP). For these reasons, vision monitoring of HDT bed rest subjects was implemented for NASA bed rest studies. Subjects selected for these studies were healthy adults (14 males and 5 females). Average age was 37.5 plus or minus 9.1 years, weight was 77.4 plus or minus 11.3 Kg, and height was 173.4 plus or minus 7.2 14 cm. Controlled conditions followed for all NASA bed rest studies were implemented. These conditions included factors such as eating a standardized diet, maintaining a strict sleep wake cycle, and remaining in bed for 24 hours each day. In one study, subjects maintained a horizontal (0 degree) position while in bed and were exercised six days per week with an integrated resistance and aerobic training (iRAT) program. In the other study, subjects were placed at 6 degrees HDT while in bed and did not engage in exercise. All subjects underwent pre- and post bed rest vision testing. While the battery of vision tests for each study was not identical, measures common to both studies will be presented. These measures included IOP and measures that provided an indication of optic disc swelling as derived from optical coherence tomography (OCT) testing: average retinal nerve fiber layer (RNFL) thickness (millimeters), disc area (square millimeters), rim area (square millimters), and average cup to disc (C

  20. Postural responses of head and foot cutaneous microvascular flow and their sensitivity to bed rest

    Science.gov (United States)

    Aratow, Michael; Hargens, Alan R.; Meyer, J.-UWE; Arnaud, Sara B.

    1991-01-01

    To explore the mechanism for facial puffiness, headache, and nasal congestion associated with microgravity and cephalad fluid shifts, the postural responses of the cutaneous microcirculation (CMC) in the forehead and dorsum of the foot of eight healthy men were studied by changing body position on a tilt table and measuring blood flows with a laser Doppler flowmeter. Increasing arterial pressure in the feet by moving from a -6-deg head-down tilt to a 60-deg head-up posture decreased foot CMC by 46.5 + or - 12.0 percent. Raising arterial pressure in the head increased forehead CMC by 25.5 + or - 0.7 percent (p less than 0.05). To investigate the possibility that these opposite responses could be modified by simulated microgravity, tilt test were repeated after 7 d of -6-deg head-down-tilt bed rest. The responses were not significantly different from those recorded before bed rest. Therefore, CMC in the feet is well regulated to prevent edema when shifting to an upright position, whereas there is less regulation in the head CMC.

  1. Bed Rest and Immobilization: Risk Factors for Bone Loss

    Science.gov (United States)

    ... Risk Factors for Bone Loss Bed Rest and Immobilization: Risk Factors for Bone Loss Like muscle, bone ... complications of pregnancy; and those who are experiencing immobilization of some part of the body because of ...

  2. The importance of prostate bed tilt during postprostatectomy intensity-modulated radiotherapy

    International Nuclear Information System (INIS)

    Bell, Linda J.; Cox, Jennifer; Eade, Thomas; Rinks, Marianne; Kneebone, Andrew

    2014-01-01

    Variations in rectal and bladder filling can create a tilt of the prostate bed, which generates the potential for a geographic miss during postprostatectomy radiotherapy. The aim of this study is to assess the effect that bladder and rectum filling has on planning target volume angle, to determine a method to assess prostate bed tilt leading to potential geographic miss, and to discuss possible implementation issues. The cone-beam computed tomography images (n = 377) of 40 patients who received postprostatectomy radiotherapy with intensity-modulated radiotherapy were reviewed. The amount of tilt in the prostate bed was defined as the angle change between 2 surgical clips, one in the upper prostate bed and another in the lower. A potential geographic miss was defined as movement of any clip of more than 1 cm in any direction or 0.5 cm posteriorly when aligned to bone anatomy. Variations in bladder and rectum size were correlated with the degree of prostate bed tilt, and the rate of potential geographic miss was determined. A possible clinical use of prostate bed tilt was then assessed for different imaging techniques. A tilt of more than 10° was seen in 20.2% of images, which resulted in a 57.9% geographic miss rate of the superior clip. When tilt remained within 10°, there was only a 9% rate of geographic miss. Potential geographic miss of the inferior surgical clip was rare, occurring in only 1.9% of all images reviewed. The most common occurrence when the prostate bed tilt increased by more than 10° was a smaller bladder and larger rectum (6.4% of all images). The most common occurrence when the prostate bed tilt decreased by more than 10° was a larger bladder and smaller rectum (1.3% of all images). Significant prostate bed tilt (>± 10°) occurred in more than 20% of images, creating a 58% rate of geographic miss. Greatest prostate bed tilt occurred when the bladder size increased or reduced by more than 2 cm or the superior rectum size increased by more

  3. The importance of prostate bed tilt during postprostatectomy intensity-modulated radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Bell, Linda J., E-mail: Linda.Bell1@health.nsw.gov.au [Northern Sydney Cancer Centre, Radiation Oncology Department, Royal North Shore Hospital, St Leonards, New South Wales (Australia); Faculty of Health Sciences, University of Sydney, Lidcombe, New South Wales (Australia); Cox, Jennifer [Northern Sydney Cancer Centre, Radiation Oncology Department, Royal North Shore Hospital, St Leonards, New South Wales (Australia); Faculty of Health Sciences, University of Sydney, Lidcombe, New South Wales (Australia); Eade, Thomas; Rinks, Marianne; Kneebone, Andrew [Northern Sydney Cancer Centre, Radiation Oncology Department, Royal North Shore Hospital, St Leonards, New South Wales (Australia)

    2014-10-01

    Variations in rectal and bladder filling can create a tilt of the prostate bed, which generates the potential for a geographic miss during postprostatectomy radiotherapy. The aim of this study is to assess the effect that bladder and rectum filling has on planning target volume angle, to determine a method to assess prostate bed tilt leading to potential geographic miss, and to discuss possible implementation issues. The cone-beam computed tomography images (n = 377) of 40 patients who received postprostatectomy radiotherapy with intensity-modulated radiotherapy were reviewed. The amount of tilt in the prostate bed was defined as the angle change between 2 surgical clips, one in the upper prostate bed and another in the lower. A potential geographic miss was defined as movement of any clip of more than 1 cm in any direction or 0.5 cm posteriorly when aligned to bone anatomy. Variations in bladder and rectum size were correlated with the degree of prostate bed tilt, and the rate of potential geographic miss was determined. A possible clinical use of prostate bed tilt was then assessed for different imaging techniques. A tilt of more than 10° was seen in 20.2% of images, which resulted in a 57.9% geographic miss rate of the superior clip. When tilt remained within 10°, there was only a 9% rate of geographic miss. Potential geographic miss of the inferior surgical clip was rare, occurring in only 1.9% of all images reviewed. The most common occurrence when the prostate bed tilt increased by more than 10° was a smaller bladder and larger rectum (6.4% of all images). The most common occurrence when the prostate bed tilt decreased by more than 10° was a larger bladder and smaller rectum (1.3% of all images). Significant prostate bed tilt (>± 10°) occurred in more than 20% of images, creating a 58% rate of geographic miss. Greatest prostate bed tilt occurred when the bladder size increased or reduced by more than 2 cm or the superior rectum size increased by more

  4. Bed Rest and Orthostatic-Hypotensive Intolerance

    Science.gov (United States)

    Schneider, Suzanne M.

    2000-01-01

    Orthostatic tolerance may be defined as the ability of humans to maintain cerebral perfusion and consciousness upon movement from a supine or sitting position to the upright posture; for example, subjects can stand suddenly or be tilted to the head-up body position. Similar but not identical physiological responses can be induced by positive G(sub Z) (head to foot) acceleration or exposure to lower body negative pressure (LBNP). The objective is to suddenly shift blood to the lower body to determine how effectively cardiovascular and neural-hormonal compensatory responses react to maintain blood pressure. In the most precise method for measuring tolerance, individuals would be stressed until they faint (syncope). However, the potential consequences and discomforts of such a test usually prohibit such a procedure so that few investigators actually induce syncope. In a more common approach, subjects are exposed to a given level of stress, for example, head-up tilt for 15 min, and any increases in heart rate or decreases in blood pressure are interpreted as indicators of progress toward syncope. Presumably, the greater the perturbation of heart rate and blood pressure, the closer to "tolerance," i.e., point of unconsciousness. Another more appropriate approach is to induce a progressively increasing hypotensive stress until pre-determined physiological responses or pre-syncopal symptoms appear. The physiological criteria may include a sudden drop in systolic blood pressure (greater than 25 mm/min), a sudden drop in heart rate (greater than 15 beats/min), or a systolic blood pressure less than 70 mmHg. The most common pre-syncopal symptoms include lightheadedness, stomach awareness or distress, feelings of warmth, tingly skin, and light to profuse sweating. Usually a combination of physiological responses and symptoms occurs such that, on different days, the tolerance time to the same orthostatic protocol is reproducible for a given individual. The assumption is that

  5. Bed rest and increased diuretic treatment in chronic congestive heart failure

    DEFF Research Database (Denmark)

    Abildgaard, U; Aldershvile, J; Ring-Larsen, H

    1985-01-01

    To elucidate the effect of bed rest used as an adjunct to increased diuretic treatment, twelve patients with chronic congestive heart failure (CHF) had a 50% increase in loop diuretic dosage and were allocated to either continuous bed rest or bed rest during nights only. The 24-hour bed rest group...... is a reasonable adjunct to diuretic treatment in patients with CHF....

  6. Physiological and Functional Alterations after Spaceflight and Bed Rest.

    Science.gov (United States)

    Mulavara, Ajitkumar P; Peters, Brian T; Miller, Chris A; Kofman, Igor S; Reschke, Millard F; Taylor, Laura C; Lawrence, Emily L; Wood, Scott J; Laurie, Steven S; Lee, Stuart M C; Buxton, Roxanne E; May-Phillips, Tiffany R; Stenger, Michael B; Ploutz-Snyder, Lori L; Ryder, Jeffrey W; Feiveson, Alan H; Bloomberg, Jacob J

    2018-04-03

    Exposure to microgravity causes alterations in multiple physiological systems, potentially impacting the ability of astronauts to perform critical mission tasks. The goal of this study was to determine the effects of spaceflight on functional task performance and to identify the key physiological factors contributing to their deficits. A test battery comprised of 7 functional tests and 15 physiological measures was used to investigate the sensorimotor, cardiovascular and neuromuscular adaptations to spaceflight. Astronauts were tested before and after 6-month spaceflights. Subjects were also tested before and after 70 days of 6° head-down bed rest, a spaceflight analog, to examine the role of axial body unloading on the spaceflight results. These subjects included Control and Exercise groups to examine the effects of exercise during bed rest. Spaceflight subjects showed the greatest decrement in performance during functional tasks that required the greatest demand for dynamic control of postural equilibrium which was paralleled by similar decrements in sensorimotor tests that assessed postural and dynamic gait control. Other changes included reduced lower limb muscle performance and increased heart rate to maintain blood pressure. Exercise performed during bed rest prevented detrimental change in neuromuscular and cardiovascular function, however, both bed rest groups experienced functional and balance deficits similar to spaceflight subjects. Bed rest data indicates that body support unloading experienced during spaceflight contributes to postflight postural control dysfunction. Further, the bed rest results in the Exercise group of subjects confirm that resistance and aerobic exercises performed during spaceflight can play an integral role in maintaining neuromuscular and cardiovascular function, which can help in reducing decrements in functional performance. These results indicate that a countermeasure to mitigate postflight postural control dysfunction is

  7. Aerobic exercise deconditioning and countermeasures during bed rest.

    Science.gov (United States)

    Lee, Stuart M C; Moore, Alan D; Everett, Meghan E; Stenger, Michael B; Platts, Steven H

    2010-01-01

    Bed rest is a well-accepted model for spaceflight in which the physiologic adaptations, particularly in the cardiovascular system, are studied and potential countermeasures can be tested. Bed rest without countermeasures results in reduced aerobic capacity and altered submaximal exercise responses. Aerobic endurance and factors which may impact prolonged exercise, however, have not been well studied. The initial loss of aerobic capacity is rapid, occurring in parallel with the loss of plasma volume. Thereafter, the reduction in maximal aerobic capacity proceeds more slowly and is influenced by central and peripheral adaptation. Exercise capacity can be maintained during bed rest and may be improved during recovery with appropriate countermeasures. Plasma volume restoration, resistive exercise, orthostatic stress, aerobic exercise, and aerobic exercise plus orthostatic stress all have been tested with varying levels of success. However, the optimal combination of elements-exercise modality, intensity, duration, muscle groups exercised and frequency of aerobic exercise, orthostatic stress, and supplementary resistive or anaerobic exercise training-has not been systematically evaluated. Currently, frequent (at least 3 days per week) bouts of intense exercise (interval-style and near maximal) with orthostatic stress appears to be the most efficacious method to protect aerobic capacity during bed rest. Further refinement of protocols and countermeasure hardware may be necessary to insure the success of countermeasures in the unique environment of space.

  8. Effects of strict prolonged bed rest on cardiorespiratory fitness

    DEFF Research Database (Denmark)

    Ried-Larsen, Mathias; Aarts, Hugo M; Joyner, Michael J

    2017-01-01

    The aim of this systematic review and meta-analysis [International Prospective Register of Systematic Reviews (PROSPERO) CRD42017055619] was to assess the effects of strict prolonged bed rest (without countermeasures) on maximal oxygen uptake (V̇o2max) and to explore sources of variation therein....

  9. Intensive Exercise Training During Bed Rest Attenuates Deconditioning

    Science.gov (United States)

    Greenleaf, John E.

    1997-01-01

    Intensive exercise training during bed rest attenuates deconditioning. Med. Sci. Sports Exerc., Vol. 29, No. 2, pp. 207-215, 1997. A 30-d 6 deg head-down bed rest project was conducted to evaluate variable high-intensity, short-duration, isotonic cycle ergometer exercise (ITE) training and high-intensity intermittent resistive isokinetic exercise (IKE) training regimens designed to maintain peak VO2 and muscle mass, strength, and endurance at ambulatory control levels throughout prolonged bed rest. Other elements of the deconditioning (adaptive) syndrome, such as proprioception, psychological performance, hypovolemia, water balance, body composition, and orthostatic tolerance, were also measured. Major findings are summarized in this paper. Compared with response during bed rest of the no exercise (NOE) control group: the ITE training regimen (a) maintained work capacity (peak VO2), (b) maintained plasma and red cell volumes, (c) induced positive body water balance, (d) decreased quality of sleep and mental concentration, and (e) had no effect on the decrease in orthostatic tolerance; the IKE training regimen (f) attenuated the decrease in peak VO2 by 50%, (g) attenuated loss of red cell volume by 40% but had no effect on loss of plasma volume, (b) induced positive body water balance, (i) had no adverse effect on quality of sleep or concentration, and 0) had no effect on the decrease in orthostatic tolerance. These findings suggest that various elements of the deconditioning syndrome can be manipulated by duration and intensity of ITE or IKE training regimens and that several different training protocols will be required to maintain or restore physiological and psychological performance of individuals confined to prolonged bed rest.

  10. Vestibular brain changes within 70 days of head down bed rest.

    Science.gov (United States)

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

    2018-03-12

    Head-down-tilt bed rest (HDBR) is frequently utilized as a spaceflight analog research environment to study the effects of axial body unloading and fluid shifts that are associated with spaceflight in the absence of gravitational modifications. HDBR has been shown to result in balance changes, presumably due to sensory reweighting and adaptation processes. Here, we examined whether HDBR results in changes in the neural correlates of vestibular processing. Thirteen men participated in a 70-day HDBR intervention; we measured balance, functional mobility, and functional brain activity in response to vestibular stimulation at 7 time points before, during, and after HDBR. Vestibular stimulation was administered by means of skull taps, resulting in activation of the vestibular cortex and deactivation of the cerebellar, motor, and somatosensory cortices. Activation in the bilateral insular cortex, part of the vestibular network, gradually increased across the course of HDBR, suggesting an upregulation of vestibular inputs in response to the reduced somatosensory inputs experienced during bed rest. Furthermore, greater increase of activation in multiple frontal, parietal, and occipital regions in response to vestibular stimulation during HDBR was associated with greater decrements in balance and mobility from before to after HDBR, suggesting reduced neural efficiency. These findings shed light on neuroplastic changes occurring with conditions of altered sensory inputs, and reveal the potential for central vestibular-somatosensory convergence and reweighting with bed rest. © 2018 Wiley Periodicals, Inc.

  11. Changes in Cartilage Morphology of the Knee after 14-days of Bed Rest

    Science.gov (United States)

    Liphardt, A.-M.; Mündermann, A.; Koo, S.; Bäcker, N.; Andriacchi, T.; Zange, J.; Mester, J.; Heer, M.

    Introduction While there are still many unanswered questions related to the effects of space flight and disuse on cartilage health and cartilage morphology the number of in vivo experiments in humans is small For muscle and bone tissue it is well known that unloading results in degeneration of those tissues Also for cartilage previous studies in patients suggest that unloading causes cartilage degeneration Studies using immobilization as a model of unloading help to investigate the importance of experiencing mechanical loads for the maintenance of healthy biological tissues The goal of our study was to investigate whether bed rest induced immobilization has a negative effect on articular cartilage in healthy subjects and if vibration training is a potential counter-measure for these negative effects Methods Eight male healthy subjects 78 1 pm 9 5 kg 179 pm 9 6 cm 26 pm 5 years performed a 14-day bed rest in 6 r -head down tilt HDT The study was designed in a cross-over-design where each subject received a training intervention vib in one phase and no intervention con in the other phase During the training intervention subjects trained 2 x 5-minutes per day at 20 Hz with 2 -- 4 mm amplitude on a vibration plate Galileo 900 Magnet resonance MR imaging of the right knee was performed to measure articular cartilage thickness MR-images 2 mm slice thickness 0 35 mm x 0 35 mm in-plane resolution 448 x 512 pixels were taken before and after bed rest to investigate the effects of bed rest

  12. Gender Differences in Isokinetic Strength after 60 and 90 d Bed Rest

    Science.gov (United States)

    English, K. L.; Ploutz-Snyder, R. J.; Cromwell, R. L.; Ploutz-Snyder, L. L.

    2010-01-01

    Recent reports suggest that changes in muscle strength following disuse may differ between males and females. PURPOSE: To examine potential gender differences in strength changes following 60 and 90 d of experimental bed rest. METHODS: Isokinetic extensor and flexor strength of the knee (60deg and 180deg/s, concentric only), ankle (30deg/s, concentric and eccentric), and trunk (60deg/s, concentric only) were measured following 60 d (males: n=4, 34.5+/-9.6 y; females: n=4, 35.5+/-8.2 y) and 90 d (males: n=10, 31.4+/-4.8 y; females: n=5, 37.6+/-9.9 y) of 6-degree head-down-tilt bed rest (BR; N=23). Subjects were fed a controlled diet (55%/15%/ 30%, CHO/PRO/FAT) that maintained body weight within 3% of the weight recorded on Day 3 of bed rest. After a familiarization session, testing was conducted 6 d before BR and 2 d after BR completion. Peak torque and total work were calculated for the tests performed. To allow us to combine data from both 60- and 90-d subjects, we used a mixed-model statistical analysis in which time and gender were fixed effects and bed rest duration was a random effect. Log-transformations of strength measures were utilized when necessary in order to meet statistical assumptions. RESULTS: Main effects were seen for both time and gender (p<0.05), showing decreased strength in response to bed rest for both males and females, and males stronger than females for most strength measures. Only one interaction effect was observed: females exhibited a greater loss of trunk extensor peak torque at 60 d versus pre-BR, relative to males (p=0.004). CONCLUSION: Sixty and 90 d of BR induced significant losses in isokinetic muscle strength of the locomotor and postural muscles of the knee, ankle, and trunk. Although males were stronger than females for most of the strength measures that we examined, only changes in trunk extensor peak torque were greater for females than males at day 60 of bed rest

  13. Cancellous bone structure of iliac crest biopsies following 370 days of head-down bed rest

    DEFF Research Database (Denmark)

    Thomsen, Jesper Skovhus; Morukov, Boris V.; Vico, Laurence

    2005-01-01

    INTRODUCTION: Static bone histomorphometry was applied to existing iliac bone sections originating from a 370-d 5 degrees head-down bed rest experiment. This bed rest experiment is the longest ever to have been conducted. We hypothesized that bed rest would decrease cancellous bone volume fractio...

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

    Science.gov (United States)

    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

  15. Surveillance of Ocular Parameters and Visual Function in Bed Rest Subjects

    Science.gov (United States)

    Cromwell, Ronita L.

    2011-01-01

    Recent visual changes in astronauts have raised concern about ocular health during long duration spaceflight. Seven cases have been documented in astronauts who spent 6 months aboard the International Space Station. These astronauts were male ranging in age from 45 to 55 years old. All astronauts exhibited pre- to post flight refractive changes. Decreased intraocular pressure (IOP) post flight was observed in 3 cases. Fundoscopic exams revealed post flight findings of choroidal folds in 4 cases, optic disc edema in 5 cases and the presence of cotton wool spots in 3 cases. Optical coherence tomography (OCT) confirmed findings of choroidal folds and disc edema, and also documented retinal nerve fiber layer thickening (5 cases). Findings from MRI examinations showed posterior globe flattening (5 cases), optic nerve sheath distention (6 cases) and torturous optic nerves (2 cases). Of the 7 cases, intracranial pressure was measured on 4 astronauts. These 4 showed elevated ICP post-flight that remained elevated for as long as 19 months in one case. While the etiology remains unknown, hypotheses speculate that venous insufficiency or hypertension in the brain caused by cephalad fluid shifts during spaceflight are possible mechanisms for ocular changes seen in astronauts. Head-down tilt bed rest is a spaceflight analog that induces cephalad fluid shifts. This study is designed to provide ocular monitoring of bed rest subjects and determine whether clinically relevant changes are found. Ocular Changes

  16. Exercise Effects on the Brain and Sensorimotor Function in Bed Rest

    Science.gov (United States)

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

    2016-01-01

    Long duration spaceflight microgravity results in cephalad fluid shifts and deficits in posture control and locomotion. Effects of microgravity on sensorimotor function have been investigated on Earth using head down tilt bed rest (HDBR). HDBR serves as a spaceflight analogue because it mimics microgravity in body unloading and bodily fluid shifts. Preliminary results from our prior 70 days HDBR studies showed that HDBR is associated with focal gray matter (GM) changes and gait and balance deficits, as well as changes in brain functional connectivity. In consideration of the health and performance of crewmembers we investigated whether exercise reduces the effects of HDBR on GM, functional connectivity, and motor performance. Numerous studies have shown beneficial effects of exercise on brain health. We therefore hypothesized that an exercise intervention during HDBR could potentially mitigate the effects of HDBR on the central nervous system. Eighteen subjects were assessed before (12 and 7 days), during (7, 30, and 70 days) and after (8 and 12 days) 70 days of 6-degrees HDBR at the NASA HDBR facility in UTMB, Galveston, TX, US. Each subject was randomly assigned to a control group or one of two exercise groups. Exercise consisted of daily supine exercise which started 20 days before the start of HDBR. The exercise subjects participated either in regular aerobic and resistance exercise (e.g. squat, heel raise, leg press, cycling and treadmill running), or aerobic and resistance exercise using a flywheel apparatus (rowing). Aerobic and resistance exercise intensity in both groups was similar, which is why we collapsed the two exercise groups for the current experiment. During each time point T1-weighted MRI scans and resting state functional connectivity scans were obtained using a 3T Siemens scanner. Focal changes over time in GM density were assessed using voxel based morphometry (VBM8) under SPM. Changes in resting state functional connectivity was assessed

  17. Mechanisms for decreased exercise capacity after bed rest in normal middle-aged men

    International Nuclear Information System (INIS)

    Hung, J.; Goldwater, D.; Convertino, V.A.; McKillop, J.H.; Goris, M.L.; DeBusk, R.F.

    1983-01-01

    The mechanisms responsible for the decrease in exercise capacity after bed rest were assessed in 12 apparently healthy men aged 50 +/- 4 years who underwent equilibrium gated blood pool scintigraphy during supine and upright multistage bicycle ergometry before and after 10 days of bed rest. After bed rest, echocardiographically measured supine resting left ventricular end-diastolic volume decreased by 16% (p less than 0.05). Peak oxygen uptake during supine effort after bed rest was diminished by 6% (p . not significant [NS]), whereas peak oxygen uptake during upright effort declined by 15% (p less than 0.05). After bed rest, increases in heart rate were also greater during exercise in the upright than in the supine position (p less than 0.05). Values of left ventricular ejection fraction increased normally during both supine and upright effort after bed rest and were higher than corresponding values before bed rest (p less than 0.05). After bed rest, increased left ventricular ejection fraction and heart rate largely compensated for the reduced cardiac volume during supine effort, but these mechanisms were insufficient to maintain oxygen transport capacity at levels during upright effort before bed rest. These results indicate that orthostatically induced cardiac underfilling, not physical deconditioning or left ventricular dysfunction, is the major cause of reduced effort tolerance after 10 days of bed rest in normal middle-aged men

  18. Gender Differences in Baroreflex Sensitivity after Bed Rest

    Science.gov (United States)

    Arzeno, Natalia M.; Stenger, M. B.; Ribeiro, L. C.; Lee, S. M.; Platts, S. H.

    2009-01-01

    Two potential contributing factors to post-spaceflight orthostatic intolerance are decreases in baroreflex sensitivity (BRS) and sympathetic nervous system response. The purpose of this study was to examine the shape of the BRS curve and sympathetic response to a wide range of blood pressures (BP) before and during 6 head-down bed rest (BR). METHODS: Normal volunteers were tested one day before BR (20M, 1 0F) and near BR days 30 (20M, 10F), 60 (16M, 8F), and 90 (1 0M, 5F). BP was pharmacologically manipulated by 10-min infusions of phenylephrine (PE) and sodium nitroprusside (SNP) at 3 increasing concentrations with a 20-min rest between PE and SNP. Electrocardiogram and continuous finger blood pressure were recorded. A blood sample was drawn at the end of each infusion to measure plasma norepinephrine levels. The spontaneous baroreflex slope (SBS), a measure of BRS, was calculated as the slope of a sequence of 3 or more beats in which the systolic BP (SBP) and following R-R interval (RR) both increased or decreased. The data included saturated responses at the upper but not the lower end of the BP range. Mean response curves were constructed using second-order mixed model analysis. Results are based on term significance in the models. RESULTS RR: RR was lower during BR than pre BR (pgenders were modeled by a linear response; compared to males, females had an attenuated (lower slope) RR response to changes in SBP (p=0.031). SBS: SBS vs SBP analysis showed a lower SBS during BR (pgender and BR. Not only do gender and BR baseline differences exist, but gender and BR also influence the slope and saturation of the BRS curves. Attenuated and saturating RR and SBS responses, as well as differences in baseline values, may contribute to the higher rates of orthostatic intolerance in women and after bed rest.

  19. Static Histomorphometry of the iliac crest after 360 days of antiorthostatic bed rest with and without countermeasures

    Science.gov (United States)

    Thomsen, J. S.; Morukov, B. V.; Vico, L.; Saparin, P. I.; Gowin, W.

    The loss of bone during immobilization is well-known and investigated, whereas the structural changes human cancellous bone undergoes during disuse is less well examined. The aim of the study was to examine the influence of hypokinesia on the static histomorphometric measures of the iliac crest using a 360-day-long bed rest experiment, simulating exposure to microgravity. Eight healthy males underwent 360 days of 5° head-down tilt bed rest. Three subjects were treated with the bisphosphonate Xidifon (900 mg/day) combined with a treadmill and ergonometer exercise regimen (1--2 hours/day) for the entire study period. Five subjects underwent 120 days of bed rest without countermeasures followed by 240 days of bed rest with the treadmill and ergonometer exercise regimen. Transiliac bone biopsies were obtained either at day 0 and 360 or at day 0, 120, and 360 at alternating sides of the ileum. The biopsies were embedded in methylmethacrylate, cut in 7-μm-thick sections, stained with Goldner trichrome, and static histomorphometry was performed. 120 days of bed rest without countermeasures resulted in decreased trabecular bone volume (-6.3%, p = 0.046) and trabecular number (-10.2%, p = 0.080) and increased trabecular separation (14.7%, p = 0.020), whereas 240 days of subsequent bed rest with exercise treatment prevented further significant deterioration of the histomorphometric measures. 360 days of bed rest with bisphosphonate and exercise treatment did not induce any significant changes in any of the histomorphometric measures. The study showed that 120 days of antiorthostatic bed rest without countermeasures induced significant deterioration of iliac crest trabecular bone histomorphometric properties. There are indications that the immobilization induced changes involve a loss of trabeculae rather than a general thinning of the trabeculae. On average, the countermeasures consisting of either bisphosphonate and exercise or exercise alone were able to either prevent

  20. Change of cortical foot activation following 70 days of head down bed rest.

    Science.gov (United States)

    Yuan, Peng; Koppelmans, Vincent; Reuter-Lorenz, Patricia; De Dios, Yiri; Gadd, Nichole; Riascos, Roy; Kofman, Igor; Bloomberg, Jacob; Mulavara, Ajitkumar; Seidler, Rachael D

    2018-02-28

    Head-down tilt bed rest (HDBR) has been used as a spaceflight analog to study some of the effects of microgravity on human physiology, cognition, and sensorimotor functions. Previous studies have reported declines in balance control and functional mobility after spaceflight and HDBR. Here we investigated how the brain activation for foot movement changed with HDBR. Eighteen healthy men participated in the current HDBR study. They were in a 6{degree sign} head-down tilt position continuously for 70 days. Functional MRI scans were acquired to estimate brain activation for foot movement pre-, during- and post-HDBR. Another eleven healthy males who did not undergo HDBR participated as control subjects and were scanned at four time points. In the HDBR subjects, the cerebellum, fusiform gyrus, hippocampus, and middle occipital gyrus exhibited HDBR-related increases in activation for foot tapping, whereas no HDBR-associated activation decreases were found. For the control subjects, activation for foot tapping decreased across sessions in a couple of cerebellar regions, while no activation increase with session was found. Furthermore, we observed that less HDBR-related declines in functional mobility and balance control were associated with greater pre-to-post HDBR increases in brain activation for foot movement in several cerebral and cerebellar regions. Our results suggest that more neural control is needed for foot movement as a result of HDBR.

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

    Science.gov (United States)

    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

  2. High Intensity Exercise Countermeasures does not Prevent Orthostatic Intolerance Following Prolonged Bed Rest

    Science.gov (United States)

    Platts, Steven H.; Stenger, Michael B.; Ploutz-Snyder, Lori L.; Lee, Stuart M. C.

    2014-01-01

    Approximately 20% of Space Shuttle astronauts became presyncopal during operational stand and 80deg head-up tilt tests, and the prevalence of orthostatic intolerance increases after longer missions. Greater than 60% of the US astronauts participating in Mir and early International Space Station missions experienced presyncope during post-flight tilt tests, perhaps related to limitations of the exercise hardware that prevented high intensity exercise training until later ISS missions. The objective of this study was to determine whether an intense resistive and aerobic exercise countermeasure program designed to prevent cardiovascular and musculoskeletal deconditioning during 70 d of bed rest (BR), a space flight analog, would protect against post-BR orthostatic intolerance. METHODS Twenty-six subjects were randomly assigned to one of three groups: non-exercise controls (n=11) or one of two exercise groups (ExA, n=8; ExB, n=7). Both ExA and ExB groups performed the same resistive and aerobic exercise countermeasures during BR, but one exercise group received testosterone supplementation while the other received a placebo during BR in a double-blinded fashion. On 3 d/wk, subjects performed lower body resistive exercise and 30 min of continuous aerobic exercise (=75% max heart rate). On the other 3 d/wk, subjects performed only highintensity, interval-style aerobic exercise. Orthostatic intolerance was assessed using a 15-min 80? head-up tilt test performed 2 d (BR-2) before and on the last day of BR (BR70). Plasma volume was measured using carbon monoxide rebreathing on BR-3 and before rising on the first recovery day (BR+0). The code for the exercise groups has not been broken, and results are reported here without group identification. RESULTS Only one subject became presyncopal during tilt testing on BR-2, but 7 of 11 (63%) controls, 3 of 8 (38%) ExA, and 4 of 7 (57%) ExB subjects were presyncopal on BR70. Survival analysis of post-BR tilt tests revealed no

  3. Fibroblast Growth Factor-23 in Bed Rest and Spaceflight

    Science.gov (United States)

    Bokhari, R.; Zwart, S. R; Fields, E.; Heer, M.; Sibonga, J.; Smith, S. M.

    2014-01-01

    Many nutritional factors influence bone, from the basics of calcium and vitamin D, to factors which influence bone through acid/base balance, including protein, sodium, and more. Fibroblast growth factor 23 (FGF23) is a recently identified factor, secreted from osteocytes, which is involved in classic (albeit complex) feedback loops controlling phosphorus homeostasis through both vitamin D and parathyroid hormone (PTH) (1, 2). As osteocytes are gravity sensing cells, it is important to determine if there are changes in FGF23 during spaceflight. In extreme cases, such as chronic kidney disease, FGF23 levels are highly elevated. FGF23 imbalances, secondary to dietary influences, may contribute to skeletal demineralization and kidney stone risk during spaceflight. Presented with an imbalanced dietary phosphorus to calcium ratio, increased secretion of FGF23 will inhibit renal phosphorus reabsorption, resulting in increased excretion and reduced circulating phosphorus. Increased intake and excretion of phosphorus is associated with increased kidney stone risk in both the terrestrial and microgravity environments. Highly processed foods and carbonated beverages are associated with higher phosphorus content. Ideally, the dietary calcium to phosphorus ratio should be at minimum 1:1. Nutritional requirements for spaceflight suggest that this ratio not be less than 0.67 (3), while the International Space Station (ISS) menu provides 1020 mg Ca and 1856 mg P, for a ratio of 0.55 (3). Subjects in NASA's bed rest studies, by design, have consumed intake ratios much closer to 1.0 (4). FGF23 also has an inhibitory influence on PTH secretion and 1(alpha)-hydroxylase, both of which are required for activating vitamin D with the conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D. Decreased 1,25-dihydroxyvitamin D will result in decreased intestinal phosphorus absorption, and increased urinary phosphorus excretion (via decreased renal reabsorption). Should a decrease in 1

  4. Resistance exercise prevents plantar flexor deconditioning during bed rest

    Science.gov (United States)

    Bamman, M. M.; Hunter, G. R.; Stevens, B. R.; Guilliams, M. E.; Greenisen, M. C.

    1997-01-01

    Because resistance exercise (REX) and unloading induce opposing neuromuscular adaptations, we tested the efficacy of REX against the effects of 14 d of bed rest unloading (BRU) on the plantar flexor muscle group. Sixteen men were randomly assigned to no exercise (NOE, N = 8) or REX (N = 8). REX performed 5 sets x 6-10 repetitions to failure of constant resistance concentric/eccentric plantar flexion every other day during BRU. One-repetition maximum (1RM) strength was tested on the training device. The angle-specific torque-velocity relationship across 5 velocities (0, 0.52, 1.05, 1.75, and 2.97 rad.s-1) and the full range-of-motion power-velocity relationship were assessed on a dynamometer. Torque-position analyses identified strength changes at shortened, neutral, and stretched muscle lengths. Concentric and eccentric contractile work were measured across ten repetitions at 1.05 rad.s-1. Maximal neural activation was measured by surface electromyography (EMG). 1RM decreased 9% in NOE and improved 11% in REX (P joint positions. Concentric (15%) and eccentric (11%) contractile work fell in NOE (P < 0.05) but not in REX. Maximal plantar flexor EMG did not change in either group. In summary, constant resistance concentric/eccentric REX completely prevented plantar flexor performance deconditioning induced by BRU. The reported benefits of REX should prove useful in prescribing exercise for astronauts in microgravity and for patients susceptible to functional decline during bed- or chair-bound hospital stays.

  5. Highly demanding resistive vibration exercise program is tolerated during 56 days of strict bed-rest.

    NARCIS (Netherlands)

    Rittweger, J.; Belavy, D.; Hunek, P.; Gast, U.; Boerst, H.; Feilcke, B.; Armbrecht, G.; Mulder, E.R.; Schubert, H.; Richardson, C.; de Haan, A.; Stegeman, D.F.; Schiessl, H.; Felsenberg, D.

    2006-01-01

    Several studies have tried to find countermeasures against musculoskeletal de-conditioning during bed rest, but none of them yielded decisive results. We hypothesised that resistive vibration exercise (RVE) might be a suitable training modality. We have therefore carried out a bed-rest study to

  6. Highly demanding resistive vibration exercise program is tolerated during 56 days of strict bed-rest.

    NARCIS (Netherlands)

    Rittweger, J.; Belavy, D.; Hunek, P.; Gast, U.; Boerst, H.; Feilcke, B.; Armbrecht, G.; Mulder, E.; Schubert, H.; Richardson, C.; Haan, A. de; Stegeman, D.F.; Schiessl, H.; Felsenberg, D.

    2006-01-01

    Several studies have tried to find countermeasures against musculoskeletal de-conditioning during bed-rest, but none of them yielded decisive results. We hypothesised that resistive vibration exercise (RVE) might be a suitable training modality. We have therefore carried out a bed-rest study to

  7. Exercise-induced pyruvate dehydrogenase activation is not affected by 7 days of bed rest

    DEFF Research Database (Denmark)

    Kiilerich, Kristian; Jørgensen, Stine Ringholm; Biensø, Rasmus Sjørup

    2011-01-01

    To test the hypothesis that physical inactivity impairs the exercise-induced modulation of pyruvate dehydrogenase (PDH), 6 healthy normally physically active male subjects completed 7 days of bed rest. Before and immediately after the bed rest, the subjects completed an OGTT and a one-legged knee...

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

    Science.gov (United States)

    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 (pcontrol. But, already on the 2nd day of immobilization both bone resorption markers significantly increased. NTX-excretion was increased by 28.7 +/- 14.0% (pcontrol. In contrast to the bone resorption markers, the formation marker P-I-CP tended to decrease as early as the fifth day of immobilization (phormone-, as well as bAP concentrations were unchanged. We conclude from these results of a pronounced rise of bone resorption markers that already 24 hours of immobilization induce a significant rise in osteoclast

  9. Bed rest attenuates sympathetic and pressor responses to isometric exercise in antigravity leg muscles in humans.

    Science.gov (United States)

    Kamiya, Atsunori; Michikami, Daisaku; Shiozawa, Tomoki; Iwase, Satoshi; Hayano, Junichiro; Kawada, Toru; Sunagawa, Kenji; Mano, Tadaaki

    2004-05-01

    Although spaceflight and bed rest are known to cause muscular atrophy in the antigravity muscles of the legs, the changes in sympathetic and cardiovascular responses to exercises using the atrophied muscles remain unknown. We hypothesized that bed rest would augment sympathetic responses to isometric exercise using antigravity leg muscles in humans. Ten healthy male volunteers were subjected to 14-day 6 degrees head-down bed rest. Before and after bed rest, they performed isometric exercises using leg (plantar flexion) and forearm (handgrip) muscles, followed by 2-min postexercise muscle ischemia (PEMI) that continues to stimulate the muscle metaboreflex. These exercises were sustained to fatigue. We measured muscle sympathetic nerve activity (MSNA) in the contralateral resting leg by microneurography. In both pre- and post-bed-rest exercise tests, exercise intensities were set at 30 and 70% of the maximum voluntary force measured before bed rest. Bed rest attenuated the increase in MSNA in response to fatiguing plantar flexion by approximately 70% at both exercise intensities (both P antigravity leg muscles.

  10. The metabolic cost of an integrated exercise program performed during 14 days of bed rest.

    Science.gov (United States)

    Scott, Jessica M; Hackney, Kyle; Downs, Meghan; Guined, Jamie; Ploutz-Snyder, Robert; Fiedler, James; Cunningham, David; Ploutz-Snyder, Lori

    2014-06-01

    Exercise countermeasures designed to mitigate muscle atrophy during long-duration spaceflight may not be as effective if crewmembers are in negative energy balance (energy output > energy input). This study determined the energy cost of supine exercise (resistance, interval, aerobic) during the spaceflight analogue of bed rest. Nine subjects (eight men and one woman; 34.5 +/- 8.2 yr) completed 14 d of bed rest and concomitant exercise countermeasures. Body mass and basal metabolic rate (BMR) were assessed before and during bed rest. Exercise energy expenditure was measured during and immediately after [excess post-exercise oxygen consumption (EPOC)] each of five different exercise protocols (30-s, 2-min, and 4-min intervals, continuous aerobic, and a variety of resistance exercises) during bed rest. On days when resistance and continuous aerobic exercise were performed daily, energy expenditure was significantly greater (2879 +/- 280 kcal) than 2-min (2390 +/- 237 kcal), 30-s (2501 +/- 264 kcal), or 4-min (2546 +/- 264 kcal) exercise. There were no significant differences in BMR (pre-bed rest: 1649 +/- 216 kcal; week 1: 1632 +/- 174 kcal; week 2:1657 +/- 176 kcal) or body mass (pre-bed rest: 75.2 +/- 10.1 kg; post-bed rest: 75.2 +/- 9.6 kg). These findings highlight the importance of energy balance for long-duration crewmembers completing a high-intensity exercise program with multiple exercise sessions daily.

  11. Long-Duration Space Flight and Bed Rest Effects on Testosterone and Other Steroids

    Science.gov (United States)

    Heer, Martina; Wang, Zuwei; Huntoon, Carolyn L.; Zwart, Sara R.

    2012-01-01

    Context: Limited data suggest that testosterone is decreased during space flight, which could contribute to bone and muscle loss. Objective: The main objective was to assess testosterone and hormone status in long- and short-duration space flight and bed rest environments and to determine relationships with other physiological systems, including bone and muscle. Design: Blood and urine samples were collected before, during, and after long-duration space flight. Samples were also collected before and after 12- to 14-d missions and from participants in 30- to 90-d bed rest studies. Setting: Space flight studies were conducted on the International Space Station and before and after Space Shuttle missions. Bed rest studies were conducted in a clinical research center setting. Data from Skylab missions are also presented. Participants: All of the participants were male, and they included 15 long-duration and nine short-duration mission crew members and 30 bed rest subjects. Main Outcome Measures: Serum total, free, and bioavailable testosterone were measured along with serum and urinary cortisol, serum dehydroepiandrosterone, dehydroepiandrosterone sulfate, and SHBG. Results: Total, free, and bioavailable testosterone was not changed during long-duration space flight but were decreased (P space flight. There were no changes in other hormones measured. Testosterone concentrations dropped before and soon after bed rest, but bed rest itself had no effect on testosterone. Conclusions: There was no evidence for decrements in testosterone during long-duration space flight or bed rest. PMID:22049169

  12. Branched-chain amino acid supplementation during bed rest: effect on recovery

    Science.gov (United States)

    Stein, T. P.; Donaldson, M. R.; Leskiw, M. J.; Schluter, M. D.; Baggett, D. W.; Boden, G.

    2003-01-01

    Bed rest is associated with a loss of protein from the weight-bearing muscle. The objectives of this study are to determine whether increasing dietary branched-chain amino acids (BCAAs) during bed rest improves the anabolic response after bed rest. The study consisted of a 1-day ambulatory period, 14 days of bed rest, and a 4-day recovery period. During bed rest, dietary intake was supplemented with either 30 mmol/day each of glycine, serine, and alanine (group 1) or with 30 mmol/day each of the three BCAAs (group 2). Whole body protein synthesis was determined with U-(15)N-labeled amino acids, muscle, and selected plasma protein synthesis with l-[(2)H(5)]phenylalanine. Total glucose production and gluconeogenesis from alanine were determined with l-[U-(13)C(3)]alanine and [6,6-(2)H(2)]glucose. During bed rest, nitrogen (N) retention was greater with BCAA feeding (56 +/- 6 vs. 26 +/- 12 mg N. kg(-1). day(-1), P < 0.05). There was no effect of BCAA supplementation on either whole body, muscle, or plasma protein synthesis or the rate of 3-MeH excretion. Muscle tissue free amino acid concentrations were increased during bed rest with BCAA (0.214 +/- 0.066 vs. 0.088 +/- 0.12 nmol/mg protein, P < 0.05). Total glucose production and gluconeogenesis from alanine were unchanged with bed rest but were significantly reduced (P < 0.05) with the BCAA group in the recovery phase. In conclusion, the improved N retention during bed rest is due, at least in part, to accretion of amino acids in the tissue free amino acid pools. The amount accreted is not enough to impact protein kinetics in the recovery phase but does improve N retention by providing additional essential amino acids in the early recovery phase.

  13. Leptin signaling in skeletal muscle after bed rest in healthy humans

    DEFF Research Database (Denmark)

    Guerra, Borja; Ponce-Gonzalez, Jesus Gustavo; Morales-Alamo, David

    2014-01-01

    . Leptin receptor isoforms (OB-Rs), suppressor of cytokine signaling 3 (SOCS3) and protein tyrosine phosphatase 1B (PTP1B) protein expression and signal transducer and activator of transcription 3 (STAT3) phosphorylation were analyzed by Western blot. RESULTS: After bed rest basal insulin concentration.......4-fold after bed rest (P PTP1B in the deltoid. PTP1B was increased by 90% with bed rest in the vastus lateralis (P ... between the increase in vastus lateralis PTP1B and the increase in both basal insulin concentrations (r = 0.66, P

  14. Vitamin D: Findings from Antarctic, Bed Rest, Houston, and ISS

    Science.gov (United States)

    Zwart, Sara R.; Locke, J.; Pierson, D.; Mehta, S.; Bourbeau, Y.; Parsons, H.; Smith, S. M.

    2009-01-01

    Obtaining vitamin D is critical for space travelers because they lack ultraviolet light exposure and have an insufficient dietary supply of vitamin D. Despite the provision of 400 IU vitamin D supplements to International Space Station (ISS) early crewmembers, vitamin D status was consistently lower after flight than before flight, and in several crewmembers has decreased to levels considered clinically significant. Vitamin D has long been known to play a role in calcium metabolism, and more recently its non-calcitropic functions have been recognized. According to the results of several recent studies, functionally relevant measures indicate that the lower limit of serum 25-hydroxyvitamin D (a marker of vitamin D status) should be raised from the current 23 nmol/L to 80 nmol/L. The mean preflight serum 25-hydroxyvitamin D (25-OH vit D) for U.S. ISS crewmembers to date is 63 +/- 16 nmol/L, and after a 4- to 6-mo space flight it typically decreases 25-30% despite supplementation (400 IU/d). The sub-optimal pre- and postflight vitamin D status is an issue that needs to be addressed, to allow NASA to better define the appropriate amount of supplemental vitamin D to serve as a countermeasure against vitamin D deficiency in astronaut crews. A series of ground-based and flight studies in multiple models have been conducted, including Antarctica in winter months when UV-B radiation levels are essentially zero, bed rest where subjects are not exposed to UV-B radiation for 60-90 days, in free-living individuals in Houston, and in International Space Station crewmembers. In these studies, we looked at dose regimen and efficacy, compliance issues, as well as toxicity. Preliminary results from these studies will be presented. Together, the data from these studies will enable us to provide space crews with evidence-based recommendations for vitamin D supplementation. The findings also have implications for other persons with limited UV light exposure, including polar workers and

  15. Design and construction of an optical test bed for LISA imaging systems and tilt-to-length coupling

    International Nuclear Information System (INIS)

    Chwalla, M; Fitzsimons, E; Danzmann, K; Fernández Barranco, G; Gerberding, O; Heinzel, G; Lieser, M; Schuster, S; Schwarze, T S; Tröbs, M; Zwetz, M; Killow, C J; Perreur-Lloyd, M; Robertson, D I; Ward, H

    2016-01-01

    The laser interferometer space antenna (LISA) is a future space-based interferometric gravitational-wave detector consisting of three spacecraft in a triangular configuration. The interferometric measurements of path length changes between satellites will be performed on optical benches in the satellites. Angular misalignments of the interfering beams couple into the length measurement and represent a significant noise source. Imaging systems will be used to reduce this tilt-to-length coupling. We designed and constructed an optical test bed to experimentally investigate tilt-to-length coupling. It consists of two separate structures, a minimal optical bench and a telescope simulator. The minimal optical bench comprises the science interferometer where the local laser is interfered with light from a remote spacecraft. In our experiment, a simulated version of this received beam is generated on the telescope simulator. The telescope simulator provides a tilting beam, a reference interferometer and an additional static beam as a phase reference. The tilting beam can either be a flat-top beam or a Gaussian beam. We avoid tilt-to-length coupling in the reference interferometer by using a small photo diode placed at an image of the beam rotation point. We show that the test bed is operational with an initial measurement of tilt-to-length coupling without imaging systems. Furthermore, we show the design of two different imaging systems whose performance will be investigated in future experiments. (paper)

  16. Effects of exercise on fluid exchange and body composition in man during 14-day bed rest

    Science.gov (United States)

    Greenleaf, J. E.; Bernauer, E. M.; Juhos, L. T.; Young, H. L.; Morse, J. T.; Staley, R. W.

    1977-01-01

    A description is presented of an investigation in which body composition, fluid intake, and fluid and electrolyte losses were measured in seven normal, healthy men during three 2-wk bed-rest periods, separated by two 3-wk recovery periods. During bed rest the subjects remained in the horizontal position continuously. During the dietary control periods, body mass decreased significantly with all three regimens, including no exercise, isometric exercise, and isotonic excercise. During bed rest, body mass was essentially unchanged with no exercise, but decreased significantly with isotonic and isometric exercise. With one exception, there were no statistically significant changes in body density, lean body mass, or body fat content by the end of each of the three bed-rest periods.

  17. Branched-chain amino acid supplementation during bed rest: effect on recovery

    Science.gov (United States)

    Stein, T. P.; Donaldson, M. R.; Leskiw, M. J.; Schluter, M. D.; Baggett, D. W.; Boden, G.

    2003-01-01

    Bed rest is associated with a loss of protein from the weight-bearing muscle. The objectives of this study are to determine whether increasing dietary branched-chain amino acids (BCAAs) during bed rest improves the anabolic response after bed rest. The study consisted of a 1-day ambulatory period, 14 days of bed rest, and a 4-day recovery period. During bed rest, dietary intake was supplemented with either 30 mmol/day each of glycine, serine, and alanine (group 1) or with 30 mmol/day each of the three BCAAs (group 2). Whole body protein synthesis was determined with U-(15)N-labeled amino acids, muscle, and selected plasma protein synthesis with l-[(2)H(5)]phenylalanine. Total glucose production and gluconeogenesis from alanine were determined with l-[U-(13)C(3)]alanine and [6,6-(2)H(2)]glucose. During bed rest, nitrogen (N) retention was greater with BCAA feeding (56 +/- 6 vs. 26 +/- 12 mg N. kg(-1). day(-1), P BCAA supplementation on either whole body, muscle, or plasma protein synthesis or the rate of 3-MeH excretion. Muscle tissue free amino acid concentrations were increased during bed rest with BCAA (0.214 +/- 0.066 vs. 0.088 +/- 0.12 nmol/mg protein, P BCAA group in the recovery phase. In conclusion, the improved N retention during bed rest is due, at least in part, to accretion of amino acids in the tissue free amino acid pools. The amount accreted is not enough to impact protein kinetics in the recovery phase but does improve N retention by providing additional essential amino acids in the early recovery phase.

  18. Effects of 30-, 60-, and 90-Day Bed Rest on Postural Control in Men and Women

    Science.gov (United States)

    Esteves, Julie; Taylor, Laura C.; Vanya, Robert D.; Dean, S. Lance; Wood, Scott J.

    2011-01-01

    INTRODUCTION Head-down-tilt bed rest (HDT) has been used as a safe gr ound-based analog to mimic and develop countermeasures for the physiological effects of spaceflight, including decrements in postural stability. The purpose of this investigation was to characterize the effects of 30-, 60-, and 90-day bed rest on postural control in men and women. METHODS Twenty-nine subjects (18M,11F) underwent 13 days of ambula tory acclimatization and were placed in 6? HDT for 30 (n=12), 60 (n=8), or 90 (n=9) days, followed by 14 days of ambulatory recovery. Computerized dynamic posturography (CDP) was used to assess changes in sensory and motor components of postural control, and recovery after HDT. Sensory Organization Tests (SOTs) objectively evaluate one?s ability to effectively use or suppress visual, vestibular, and proprioceptive information for postural control. Stability during the SOTs was assessed using peak-to-peak sway and convergence toward stability limits to derive an equilibrium score. Motor Control Tests (MCTs) evaluate one?s ability to recover from unexpected support surface perturbations, with performance determined by center-of-pressure path length. Whole-body kinematic data were collected to determine body-sway strategy used to maintain stability during each condition. Baselines were determined pre-HDT. Recovery was tracked post-HDT on days 0, 1, 2, and 4. RESULTS Immediately after HDT, subjects showed decreased performance on most SOTs, primarily on sway-referenced support conditions, typically returning to baseline levels within 4 days. MCT performance was not significantly affected. There were no significant gender or duration differences in performance. Kinematic data revealed a tendency to use ankle strategy to maintain an upright stance during most SOT conditions. Interestingly, six subjects (2M,4F) experienced orthostatic intolerance and were unable to complete day 0 testing. CONCLUSION HDT mimics some un loading mechanisms of spaceflight and

  19. Temporal Changes in Left Ventricular Mechanics: Impact of Bed Rest and Exercise

    Science.gov (United States)

    Scott, Jessica M.; Matz, Timothy; Caine, Timothy; Martin, David S.; Downs, Meghan; Ploutz-Snyder, Lori

    2014-01-01

    BACKGROUND Current techniques used to assess cardiac function following spaceflight or head-down tilt bed rest (HDTBR) involve invasive and time consuming procedures such as Swan-Ganz catheterization or cardiac magnetic resonance imaging. An alternative approach, echocardiography, can monitor cardiac morphology and function via sequential measurements of left ventricular (LV) mass and ejection fraction (EF). However, LV mass and EF are insensitive measures of early (subclinical) cardiac deconditioning, and a decrease in LV mass and EF become evident only once significant deconditioning has already occurred. The use of more sensitive and specific echocardiographic techniques such as speckle tracking imaging may address the current limitations of conventional cardiac imaging techniques to provide insight into the magnitude and time course of cardiac deconditioning. METHODS Speckle tracking assessment of longitudinal, radial, and circumferential strain and twist was used to evaluate the impact of 70 days of HDTBR (n=7) and HDTBR + exercise (n=11) on temporal changes in LV mechanics. Echocardiograms were performed pre (BR-2), during (BR31, 70), and following (BR+4hr) HDTBR. Multi-level modeling was used to evaluate the effect of HDTBR condition (Control, Exercise) on cardiac variables. RESULTS Compared to BR-2, longitudinal (BR-2: - 19.0 +/- 1.8%; BR31: -15.9 +/- 2.4%; BR70: -14.9 +/- 2.4%; BR+4hr: -16.0 +/- 2.1%) and radial (BR-2: 15.0 +/- 1.9%; BR31: 12.3 +/- 2.4%; BR70: 11.3 +/- 2.2%; BR+4hr: 13.5 +/- 2.5% ) strains were significantly impaired during and following bed rest (pmechanics for longitudinal strain (BR-2: -19.1 +/- 1.5%; BR 31: -19.0 +/- 2.4%; BR70: -19.1 +/- 2.7%; BR+4hr: -17.8 +/- 2.1%), radial strain (BR-2: 13.8 +/- 2.4; BR31: 14.7 +/- 2.4; BR70: 14.4 +/- 1.6; BR+4hr: 14.4 +/- 2.4), and twist (BR-2: 17.8 +/- 3.6deg; BR31: 18.0 +/- 3.6deg; BR70: 18.2 +/- 5.9deg; BR+4hr: 18.3 +/- 4.2deg). CONCLUSIONS Speckle-tracking echocardiography provides important

  20. Bed rest reduces metabolic protein content and abolishes exercise-induced mRNA responses in human skeletal muscle

    DEFF Research Database (Denmark)

    Jørgensen, Stine Ringholm; Biensø, Rasmus S; Kiilerich, Kristian

    2011-01-01

    Background: The aim was to test the hypothesis that one week of bed rest will reduce mitochondrial number and expression and activity of oxidative proteins in human skeletal muscle, but that exercise-induced intracellular signaling as well as mRNA and microRNA (miR) responses are maintained after......-legged knee extensor exercise performed before and after bed rest. Results: Maximal oxygen uptake decreased 5% and exercise endurance decreased non-significantly 25% by bed rest. Bed rest reduced skeletal muscle mitochondrial DNA/nuclear DNA content 15%, hexokinase II and sirtuin 1 protein content ~45%, 3...... bed rest. Research Design and Methods: Twelve young, healthy, male subjects completed 7 days of bed rest with vastus lateralis muscle biopsies taken before and after bed rest. In addition, muscle biopsies were obtained from 6 of the subjects prior to, immediately after and 3h after 45 min one...

  1. Effects of Bed Rest on Conduction Velocity of the Triceps Surae Stretch Reflex and Postural Control

    Science.gov (United States)

    Reschke, M. F.; Wood, S. J.; Cerisano, J. M.; Kofman, I. S.; Fisher, E. A.; Esteves, J. T.; Taylor, L. C.; DeDios, Y. E.; Harm, D. L.

    2011-01-01

    Despite rigorous exercise and nutritional management during space missions, astronauts returning from microgravity exhibit neuromuscular deficits and a significant loss in muscle mass in the postural muscles of the lower leg. Similar changes in the postural muscles occur in subjects participating in long-duration bed rest studies. These adaptive muscle changes manifest as a reduction in reflex conduction velocity during head-down bed rest. Because the stretch reflex encompasses both the peripheral (muscle spindle and nerve axon) and central (spinal synapse) components involved in adaptation to calf muscle unloading, it may be used to provide feedback on the general condition of neuromuscular function, and might be used to evaluate the effectiveness of countermeasures aimed at preserving muscle mass and function during periods of unloading. Stretch reflexes were measured on 18 control subjects who spent 60 to 90 days in continuous 6 deg head-down bed rest. Using a motorized system capable of rotating the foot around the ankle joint (dorsiflexion) through an angle of 10 degrees at a peak velocity of about 250 deg/sec, a stretch reflex was recorded from the subject's left triceps surae muscle group. Using surface electromyography, about 300 reflex responses were obtained and ensemble-averaged on 3 separate days before bed rest, 3 to 4 times in bed, and 3 times after bed rest. The averaged responses for each test day were examined for reflex latency and conduction velocity (CV) across gender. Computerized posturography was also conducted on these same subjects before and after bed rest as part of the standard measures. Peak-to-peak sway was measured during Sensory Organization Tests (SOTs) to evaluate changes in the ability to effectively use or suppress visual, vestibular, and proprioceptive information for postural control. Although no gender differences were found, a significant increase in reflex latency and a significant decrease in CV were observed during the bed

  2. Induced venous pooling and cardiorespiratory responses to exercise after bed rest

    Science.gov (United States)

    Convertino, V. A.; Sandler, H.; Webb, P.; Annis, J. F.

    1982-01-01

    Venous pooling induced by a specially constructed garment is investigated as a possible means for reversing the reduction in maximal oxygen uptake regularly observed following bed rest. Experiments involved a 15-day period of bed rest during which four healthy male subjects, while remaining recumbent in bed, received daily 210-min venous pooling treatments from a reverse gradient garment supplying counterpressure to the torso. Results of exercise testing indicate that while maximal oxygen uptake endurance time and plasma volume were reduced and maximal heart rate increased after bed rest in the control group, those parameters remained essentially unchanged for the group undergoing venous pooling treatment. Results demonstrate the importance of fluid shifts and venous pooling within the cardiovascular system in addition to physical activity to the maintenance of cardiovascular conditioning.

  3. Repeatability of popliteal blood flow and lower limb vascular conductance at rest and exercise during body tilt using Doppler ultrasound

    International Nuclear Information System (INIS)

    Villar, R; Hughson, R L

    2013-01-01

    We tested the data repeatability for popliteal blood flow velocity (PBV), popliteal arterial diameter (AD pop ), popliteal blood flow (PBF) and lower limb vascular conductance (VC) at rest and exercise in three body positions, two work rates and two inspired oxygen fractions. Fifteen, eleven and ten healthy volunteers participated in the three phases of the studies. Resting protocols were performed in horizontal (HOR), 35° head-down tilt (HDT) and 45° head-up tilt (HUT) for 5 min in each body position. Participants also exercised at lower and higher power outputs (repeated plantar flexion contractions at 20% and 30% maximal voluntary contraction, respectively) in HOR, HDT and HUT and in normoxia (21%O 2 ) and hypoxia (14%O 2 ) with the same work rates and body positions. PBV and AD pop were measured by ultrasound to determine PBF, and VC was estimated by dividing PBF by muscle perfusion pressure (MPP). PBV, AD pop , PBF and VC were not different, demonstrated good agreement and consistency between the two days of testing during both rest and exercise conditions regardless of body position. Therefore, these data support the utilization of Doppler and echo Doppler ultrasound as a reproducible method to measure PBV and AD pop and consequently estimate PBF and VC responses in such conditions. (paper)

  4. Body Unloading Associated with Space Flight and Bed-rest Impacts Functional Performance

    Science.gov (United States)

    Bloomberg, J. J.; Ballard, K. L.; Batson, C. D.; Buxton, R. E.; Feiveson, A. H.; Kofman, I. S.; Lee, S. M. C.; Miller, C. A.; Mulavara, A. P.; Peters, B. T.; hide

    2014-01-01

    The goal of the Functional Task Test study is to determine the effects of space flight on functional tests that are representative of high priority exploration mission tasks and to identify the key underlying physiological factors that contribute to decrements in performance. Ultimately this information will be used to assess performance risks and inform the design of countermeasures for exploration class missions. We are currently conducting studies on both ISS crewmembers and on subjects experiencing 70 days of 6 degrees head-down bed-rest as an analog for space flight. Bed-rest provides the opportunity for us to investigate the role of prolonged axial body unloading in isolation from the other physiological effects produced by exposure to the microgravity environment of space flight. This allows us to parse out the contribution of the body unloading component on functional performance. In this on-going study both ISS crewmembers and bed-rest subjects were tested using an interdisciplinary protocol that evaluated functional performance and related physiological changes before and after 6 months in space and 70 days of 6? head-down bed-rest, respectively. Functional tests included ladder climbing, hatch opening, jump down, manual manipulation of objects and tool use, seat egress and obstacle avoidance, recovery from a fall, and object translation tasks. Crewmembers were tested three times before flight, and on 1, 6 and 30 days after landing. Bed-rest subjects were tested three times before bed-rest and immediately after getting up from bed-rest as well as 1, 6 and 12 days after reambulation. A comparison of bed-rest and space flight data showed a significant concordance in performance changes across all functional tests. Tasks requiring a greater demand for dynamic control of postural equilibrium (i.e. fall recovery, seat egress/obstacle avoidance during walking, object translation, jump down) showed the greatest decrement in performance. Functional tests with

  5. Vestibular and Somatosensory Covergence in Postural Equilibrium Control: Insights from Spaceflight and Bed Rest Studies

    Science.gov (United States)

    Mulavara, A. P.; Batson, C. D.; Buxton, R. E.; Feiveson, A. H.; Kofman, I. S.; Lee, S. M. C.; Miller, C. A.; Peters, B. T.; Phillips, T.; Platts, S. H.; hide

    2014-01-01

    The goal of the Functional Task Test study is to determine the effects of space flight on functional tests that are representative of high priority exploration mission tasks and to identify the key underlying physiological factors that contribute to decrements in performance. We are currently conducting studies on both International Space Station (ISS) astronauts experiencing up to 6 months of microgravity and subjects experiencing 70 days of 6??head-down bed-rest as an analog for space flight. Bed-rest provides the opportunity for us to investigate the role of prolonged axial body unloading in isolation from the other physiological effects produced by exposure to the microgravity environment of space flight. This allows us to parse out the contribution of the body unloading somatosensory component on functional performance. Both ISS crewmembers and bed-rest subjects were tested using a protocol that evaluated functional performance along with tests of postural and locomotor control before and after space flight and bed-rest, respectively. Functional tests included ladder climbing, hatch opening, jump down, manual manipulation of objects and tool use, seat egress and obstacle avoidance, recovery from a fall, and object translation tasks. Astronauts were tested three times before flight, and on 1, 6, and 30 days after landing. Bed-rest subjects were tested three times before bed-rest and immediately after getting up from bed-rest as well as 1, 6, and 12 days after re-ambulation. A comparison of bed-rest and space flight data showed a significant concordance in performance changes across all functional tests. Tasks requiring a greater demand for dynamic control of postural equilibrium (i.e. fall recovery, seat egress/obstacle avoidance during walking, object translation, jump down) showed the greatest decrement in performance. Functional tests with reduced requirements for postural stability showed less reduction in performance. Results indicate that body unloading

  6. Psychological effects of acute physical inactivty during microgravitiy simulated by bed rest

    Directory of Open Access Journals (Sweden)

    Petra Dolenc

    2009-05-01

    Full Text Available Long-duration weightlessness simulated by bed rest represents an important model to study the consequences of physical inactivity and sedentarism on the human body. This study evaluated changes of mood status, psychological well-being, coping strategies and physical self in ten healthy young male subjects during a 35-day horizontal bed rest. Participants were asked to complete psychometrical inventories before and after the bed rest experiment. The preceived satisfaction with life and the physical self-concept did not change during bed rest period and mood states were relatively stable during the experiment according to the Emotional States Questionnaire. The neurotic level was enhanced during the bed rest period according to the Slovenian version of the General Health Questionnaire. However, even after the period of physical immobilization, the expression of these symptoms remains relatively low and does not represent a risk to the mental health of the subjects. The results from Coping Resources Inventory indicated a tendency toward an increase of emotion focused coping and a decrease of problem focused coping strategies. The importance of this research was to provide evidence that the provision of favourable habitability countermeasures can prevent deterioration in the psychological state under conditions of physical immobilisation. Our findings have applied value in the field of health prevention and rehabilitaion.

  7. The effect of 8 days of strict bed rest on the incretin effect in healthy volunteers.

    Science.gov (United States)

    Nielsen, Signe Tellerup; Harder-Lauridsen, Nina Majlund; Benatti, Fabiana Braga; Wedell-Neergaard, Anne-Sophie; Lyngbæk, Mark Preben; Møller, Kirsten; Pedersen, Bente Klarlund; Krogh-Madsen, Rikke

    2016-03-15

    Bed rest and physical inactivity are the consequences of hospital admission for many patients. Physical inactivity induces changes in glucose metabolism, but its effect on the incretin effect, which is reduced in, e.g., Type 2 diabetes, is unknown. To investigate how 8 days of strict bed rest affects the incretin effect, 10 healthy nonobese male volunteers underwent 8 days of strict bed rest. Before and after the intervention, all volunteers underwent an oral glucose tolerance test (OGTT) followed by an intravenous glucose infusion (IVGI) on the following day to mimic the blood glucose profile from the OGTT. Blood glucose, serum insulin, serum C-peptide, plasma incretin hormones [glucagon-like peptide (GLP-1) and glucose-dependent insulinotropic peptide (GIP)], and serum glucagon were measured serially during both the OGTT and the IVGI. The incretin effect is calculated as the relative difference between the area under the curve for the insulin response during the OGTT and that of the corresponding IVGI, respectively. Concentrations of glucose, insulin, C-peptide, and GIP measured during the OGTT were higher after the bed rest intervention (all P effect (P = 0.6). In conclusion, 8 days of bed rest induces insulin resistance, but we did not see evidence of an associated change in the incretin effect. Copyright © 2016 the American Physiological Society.

  8. Attenuation of the protein wasting associated with bed rest by branched-chain amino acids

    Science.gov (United States)

    Stein, T. P.; Schluter, M. D.; Leskiw, M. J.; Boden, G.

    1999-01-01

    Bed rest is generally accepted as being an appropriate ground-based model for human spaceflight. The objectives of this study were to test the hypothesis that increasing the amount of branched-chain amino acids (BCAAs) in the diet could attenuate the protein loss associated with bed rest. Nineteen healthy subjects were randomized into two groups according to diet. During the 6 d of bed rest, the diets were supplemented with either 30 mmol/d each of three non-essential amino acids, glycine, serine, and alanine (control group), or with 30 mmol/d each of the BCAAs, leucine, isoleucine, and valine (BCAA group). Nutrition was supplied as a commercially available defined formula diet at a rate of 1.3 x REE. Nitrogen (N) balance and urinary 3-MeH excretion were determined for the 6 d. In our results, the urine-based estimate of N balance was 22.2 +/- 14.4 (n = 9) mg N.kg-1.d-1 and 60.5 +/- 10.1 mg (n = 8) N.kg-1.d-1 for the control and BCAA-supplemented groups, respectively (P < 0.05). Urinary 3-MeH excretion was unchanged in both groups with bed rest. We conclude that BCAA supplementation attenuates the N loss during short-term bed rest.

  9. Bed rest from the perspective of the high-risk pregnant woman.

    Science.gov (United States)

    Gupton, A; Heaman, M; Ashcroft, T

    1997-01-01

    To describe the experience of prolonged bed rest from the perspective of women during high-risk pregnancies. A focused ethnographic study that used interviews, participant diaries, and field notes as data sources. Participants were obtained from an acute-care hospital antepartum unit and an antepartum home care program. Twenty-four women with complications of pregnancy requiring prolonged bed rest (range, 7-50 days). A model of the stress process in pregnant women on bed rest emerged from the data analysis. Stressors were grouped into situational (sick role, lack of control, uncertainty, concerns regarding fetus's well-being, and being tired of waiting), environmental (feeling like a prisoner, being bored, and having a sense of missing out), and family (role reversal and worry about older children) categories. Two main mediators of stress were social support and coping. Families, friends, and professionals were perceived as sources of support. Women used coping strategies, such as keeping a positive attitude, taking it 1 day at a time, doing it for the baby, getting used to it, setting goals, and keeping busy. Manifestations of stress were evidenced by adverse physical symptoms, emotional reactions, and altered social relationships. Prolonged bed rest is a stressful experience for pregnant women at high risk. Understanding the stress process in pregnant women confined to bed rest may assist nurses in developing interventions to reduce stressors and enhance mediators.

  10. GLUT4 and glycogen synthase are key players in bed rest-induced insulin resistance

    DEFF Research Database (Denmark)

    Biensø, Rasmus Sjørup; Jørgensen, Stine Ringholm; Kiilerich, Kristian

    2012-01-01

    To elucidate the molecular mechanisms behind physical inactivity-induced insulin resistance in skeletal muscle, 12 young, healthy male subjects completed 7 days of bed rest with vastus lateralis muscle biopsies obtained before and after. In six of the subjects, muscle biopsies were taken from both...... than before bed rest. This bed rest-induced insulin resistance occurred together with reduced muscle GLUT4, hexokinase II, protein kinase B/Akt1, and Akt2 protein level, and a tendency for reduced 3-hydroxyacyl-CoA dehydrogenase activity. The ability of insulin to phosphorylate Akt and activate....... The present findings demonstrate that physical inactivity-induced insulin resistance in muscle is associated with lower content/activity of key proteins in glucose transport/phosphorylation and storage....

  11. The Metabolic Cost of a High Intensity Exercise Program During Bed Rest

    Science.gov (United States)

    Hackney, Kyle; Everett, Meghan; Guined, Jamie; Cunningham, Daid

    2012-01-01

    Background: Given that disuse-related skeletal muscle atrophy may be exacerbated by an imbalance between energy intake and output, the amount of energy required to complete exercise countermeasures is an important consideration in the well being of subject health during bed rest and spaceflight. Objective: To evaluate the energy cost of a high intensity exercise program performed during short duration bed rest. Methods: 9 subjects (8 male and 1 female; 34.5 +/- 8.2 years) underwent 14 days of bed rest and exercise countermeasures. Exercise energy expenditure and excess post exercise oxygen consumption (EPOC) were collected once in each of 5 different exercise protocols (30 second, 2 minute and 4 minute intervals, continuous aerobic and a variety of resistance exercises) during bed rest. Body mass, basal metabolic rate (BMR), upper and lower leg muscle, subcutaneous, and intramuscular adipose tissue (IMAT) volumes were assessed before and at the end of bed rest. Results: There were no significant differences in body mass (pre: 75.1 +/- 10.5 kg; post: 75.2 +/- 10.1 kg), BMR (pre: 1649 +/- 216 kcal; post: 1657 +/- 177 kcal), muscle subcutaneous, or IMAT volumes (Table 2) after 14 days of bed rest and exercise. Body mass was maintained with an average daily intake of 2710 +/- 262 kcal (36.2 +/- 2.1 kcal/kg/day), while average daily energy expenditure was 2579 +/-311 kcal (34.5 +/- 3.6 kcal/kg/day). Exercise energy expenditure was significantly greater as a result of continuous aerobic exercise than all other exercise protocols.

  12. Triiodothyronine increases calcium loss in a bed rest antigravity model for space flight.

    Science.gov (United States)

    Smith, Steven R; Lovejoy, Jennifer C; Bray, George A; Rood, Jennifer; Most, Marlene M; Ryan, Donna H

    2008-12-01

    Bed rest has been used as a model to simulate the effects of space flight on bone metabolism. Thyroid hormones accelerate bone metabolism. Thus, supraphysiologic doses of this hormone might be used as a model to accelerate bone metabolism during bed rest and potentially simulate space flight. The objective of the study was to quantitate the changes in bone turnover after low doses of triiodothyronine (T(3)) added to short-term bed rest. Nine men and 5 women were restricted to bed rest for 28 days with their heads positioned 6 degrees below their feet. Subjects were randomly assigned to receive either placebo or oral T(3) at doses of 50 to 75 microg/d in a single-blind fashion. Calcium balance was measured over 5-day periods; and T(3), thyroxine, thyroid-stimulating hormone, immunoreactive parathyroid hormone, osteocalcin, bone alkaline phosphatase, and urinary deoxypyridinoline were measured weekly. Triiodothyronine increased 2-fold in the men and 5-fold in the women during treatment, suppressing both thyroxine and thyroid-stimulating hormone. Calcium balance was negative by 300 to 400 mg/d in the T(3)-treated volunteers, primarily because of the increased fecal loss that was not present in the placebo group. Urinary deoxypyridinoline to creatinine ratio, a marker of bone resorption, increased 60% in the placebo group during bed rest, but more than doubled in the T(3)-treated subjects (P < .01), suggesting that bone resorption was enhanced by treatment with T(3). Changes in serum osteocalcin and bone-specific alkaline phosphatase, markers of bone formation, were similar in T(3)- and placebo-treated subjects. Triiodothyronine increases bone resorption and fecal calcium loss in subjects at bed rest.

  13. High Intensity Resistive and Rowing Exercise Countermeasures Do Not Prevent Orthostatic Intolerance Following 70 Days of Bed Rest

    Science.gov (United States)

    Lee, Stuart M. C.; Stenger, Michael B.; Laurie, Steven S.; Ploutz-Snyder, Lori L.; Platts, Steven H.

    2015-01-01

    More than 60% of US astronauts participating in Mir and early International Space Station missions (greater than 5 months) were unable to complete a 10-min 80 deg head-up tilt test on landing day. This high incidence of post-spaceflight orthostatic intolerance may be related to limitations of the inflight exercise hardware that prevented high intensity training. PURPOSE: This study sought to determine if a countermeasure program that included intense lower-body resistive and rowing exercises designed to prevent cardiovascular and musculoskeletal deconditioning during 70 days of 6 deg head-down tilt bed rest (BR), a spaceflight analog, also would protect against post- BR orthostatic intolerance. METHODS: Sixteen males participated in this study and performed no exercise (Control, n=10) or performed an intense supine exercise protocol with resistive and aerobic components (Exercise, n=6). On 3 days/week, exercise subjects performed lower body resistive exercise and a 30-min continuous bout of rowing (greater than or equal to 75% max heart rate). On 3 other days/week, subjects performed only high-intensity, interval-style rowing. Orthostatic intolerance was assessed using a 15-min 80 deg head-up tilt test performed 2 days (BR-2) before and on the last day of BR (BR70). Plasma volume was measured using a carbon monoxide rebreathing technique on BR-3 and before rising on the first recovery day (BR+0). RESULTS: Following 70 days of BR, tilt tolerance time decreased significantly in both the Control (BR-2: 15.0 +/- 0.0, BR70: 9.9 +/- 4.6 min, mean +/- SD) and Exercise (BR-2: 12.2 +/- 4.7, BR70: 4.9 +/- 1.9 min) subjects, but the decreased tilt tolerance time was not different between groups (Control: -34 +/- 31, Exercise: -56 +/- 16%). Plasma volume also decreased (Control: -0.56 +/- 0.40, Exercise: -0.48 +/- 0.33 L) from pre to post-BR, with no differences between groups (Control: -18 +/- 11%, Exerciser: -15 +/-1 0%). CONCLUSIONS: These findings confirm previous reports

  14. Bed Rest and Hypoxic Exposure Affect Sleep Architecture and Breathing Stability

    Directory of Open Access Journals (Sweden)

    Shawnda A. Morrison

    2017-06-01

    Full Text Available Objective: Despite over 50 years of research on the physiological effects of sustained bed rest, data characterizing its effects on sleep macrostructure and breathing stability in humans are scarce. This study was conducted to determine the effects of continuous exposure to hypoxia and sustained best rest, both individually and combined, on nocturnal sleep and breathing stability.Methods: Eleven participants completed three randomized, counter-balanced, 21-days trials of: (1 normoxic bed rest (NBR, PIO2 = 133.1 ± 0.3, (2 hypoxic ambulatory confinement (HAMB, PIO2 = 90.0 ± 0.4 and (3 hypoxic bed rest (HBR, PIO2 = 90.0 ± 0.4; ~4,000 m equivalent altitude. Full objective polysomnography was performed at baseline, on Night 1 and Night 21 in each condition.Results: In NBR Night 1, more time was spent in light sleep (10 ± 2% compared to baseline (8 ± 2%; p = 0.028; Slow-wave sleep (SWS was reduced from baseline in the hypoxic-only trial by 18% (HAMB Night 21, p = 0.028 and further reduced by 33% (HBR Night 1, p = 0.010, and 36% (HBR Night 21, p = 0.008 when combined with bed rest. The apnea-hypopnea index doubled from Night 1 to Night 21 in HBR (32–62 events·h−1 and HAMB (31–59 events·h−1; p = 0.002. Those who experienced greatest breathing instability from Night 1 to Night 21 (NBR were correlated to unchanged or higher (+1% night SpO2 concentrations (R2 = 0.471, p = 0.020.Conclusion: Bed rest negatively affects sleep macrostructure, increases the apnea-hypopnea index, and worsens breathing stability, each independently exacerbated by continuous exposure to hypoxia.

  15. Bed Rest and Hypoxic Exposure Affect Sleep Architecture and Breathing Stability

    Science.gov (United States)

    Morrison, Shawnda A.; Mirnik, Dani; Korsic, Spela; Eiken, Ola; Mekjavic, Igor B.; Dolenc-Groselj, Leja

    2017-01-01

    Objective: Despite over 50 years of research on the physiological effects of sustained bed rest, data characterizing its effects on sleep macrostructure and breathing stability in humans are scarce. This study was conducted to determine the effects of continuous exposure to hypoxia and sustained best rest, both individually and combined, on nocturnal sleep and breathing stability. Methods: Eleven participants completed three randomized, counter-balanced, 21-days trials of: (1) normoxic bed rest (NBR, PIO2 = 133.1 ± 0.3), (2) hypoxic ambulatory confinement (HAMB, PIO2 = 90.0 ± 0.4) and (3) hypoxic bed rest (HBR, PIO2 = 90.0 ± 0.4; ~4,000 m equivalent altitude). Full objective polysomnography was performed at baseline, on Night 1 and Night 21 in each condition. Results: In NBR Night 1, more time was spent in light sleep (10 ± 2%) compared to baseline (8 ± 2%; p = 0.028); Slow-wave sleep (SWS) was reduced from baseline in the hypoxic-only trial by 18% (HAMB Night 21, p = 0.028) and further reduced by 33% (HBR Night 1, p = 0.010), and 36% (HBR Night 21, p = 0.008) when combined with bed rest. The apnea-hypopnea index doubled from Night 1 to Night 21 in HBR (32–62 events·h−1) and HAMB (31–59 events·h−1; p = 0.002). Those who experienced greatest breathing instability from Night 1 to Night 21 (NBR) were correlated to unchanged or higher (+1%) night SpO2 concentrations (R2 = 0.471, p = 0.020). Conclusion: Bed rest negatively affects sleep macrostructure, increases the apnea-hypopnea index, and worsens breathing stability, each independently exacerbated by continuous exposure to hypoxia. PMID:28676764

  16. Attenuation of the protein wasting associated with bed rest by branched-chain amino acids

    Science.gov (United States)

    Stein, T. P.; Schluter, M. D.; Leskiw, M. J.; Boden, G.

    1999-01-01

    Bed rest is generally accepted as being an appropriate ground-based model for human spaceflight. The objectives of this study were to test the hypothesis that increasing the amount of branched-chain amino acids (BCAAs) in the diet could attenuate the protein loss associated with bed rest. Nineteen healthy subjects were randomized into two groups according to diet. During the 6 d of bed rest, the diets were supplemented with either 30 mmol/d each of three non-essential amino acids, glycine, serine, and alanine (control group), or with 30 mmol/d each of the BCAAs, leucine, isoleucine, and valine (BCAA group). Nutrition was supplied as a commercially available defined formula diet at a rate of 1.3 x REE. Nitrogen (N) balance and urinary 3-MeH excretion were determined for the 6 d. In our results, the urine-based estimate of N balance was 22.2 +/- 14.4 (n = 9) mg N.kg-1.d-1 and 60.5 +/- 10.1 mg (n = 8) N.kg-1.d-1 for the control and BCAA-supplemented groups, respectively (P BCAA supplementation attenuates the N loss during short-term bed rest.

  17. Effects of rehydration on +Gz tolerance after 14-days' bed rest.

    Science.gov (United States)

    Greenleaf, J. E.; Van Beaumont, W.; Bernauer, E. M.; Haines, R. F.; Sandler, H.; Staley, R. W.; Young, H. L.; Yusken, J. W.

    1973-01-01

    Investigation of the magnitude of reduction in human tolerance to centrifugation following 2 weeks of bed rest with moderate daily exercise. The degree of hypovolemia associated with these exposures is assessed, and the possibility to improve or to return to control levels the tolerance to acceleration forces acting in the head-to-foot direction through rehydration prior to acceleration is explored.

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

    Science.gov (United States)

    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.; hide

    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

  19. Prospective Evaluation of the Optimal Duration of Bed Rest After Vascular Interventions Using a 3-French Introducer Sheath

    Energy Technology Data Exchange (ETDEWEB)

    Aramaki, Takeshi, E-mail: t.aramaki@scchr.jp; Moriguchi, Michihisa, E-mail: m.moriguchi@scchr.jp; Bekku, Emima, E-mail: e.bekku@scchr.jp [Shizuoka Cancer Center, Division of Interventional Radiology (Japan); Endo, Masahiro, E-mail: m.endo@scchr.jp; Asakura, Koiku, E-mail: k.asakura@scchr.jp [Shizuoka Cancer Center, Division of Diagnostic Radiology (Japan); Boku, Narikazu, E-mail: n.boku@marianna-u.ac.jp [Shizuoka Cancer Center, Division of Medical Oncology (Japan); Yoshimura, Kenichi, E-mail: keyoshim@med.kobe-u.ac.jp [Kobe University Hospital, Center for Clinical Research (Japan)

    2015-02-15

    PurposeTo assess optimal bed-rest duration after vascular intervention by way of the common femoral artery using 3F introducer sheaths.Materials and MethodsEligibility criteria for this single-center, prospective study included clinically necessary angiography, no coagulopathy or anticoagulant therapy, no hypersensitivity to contrast medium, age >20 years, and written, informed consent. Enrolled patients were assigned to one of three groups (105/group) with the duration of bed rest deceased sequentially. A sheath was inserted by way of the common femoral artery using the Seldinger technique. The first group (level 1) received 3 h of bed rest after the vascular intervention. If no bleeding or hematomas developed, the next group (level 2) received 2.5 h of bed rest. If still no bleeding or hematomas developed, the final group (level 3) received 2 h of bed rest. If any patient had bleeding or hematomas after bed rest, the study was terminated, and the bed rest of the preceding level was considered the optimal duration.ResultsA total of 105 patients were enrolled at level 1 between November 2010 and September 2011. Eight patients were excluded from analysis because cessation of bed rest was delayed. None of the remaining subjects experienced postoperative bleeding; therefore, patient enrollment at level 2 began in September 2011. However, puncture site bleeding occurred in the 52nd patient immediately after cessation of bed rest, necessitating study termination.ConclusionTo prevent bleeding, at least 3 h of postoperative bed rest is recommended for patients undergoing angiography using 3F sheaths.

  20. Prospective Evaluation of the Optimal Duration of Bed Rest After Vascular Interventions Using a 3-French Introducer Sheath

    International Nuclear Information System (INIS)

    Aramaki, Takeshi; Moriguchi, Michihisa; Bekku, Emima; Endo, Masahiro; Asakura, Koiku; Boku, Narikazu; Yoshimura, Kenichi

    2015-01-01

    PurposeTo assess optimal bed-rest duration after vascular intervention by way of the common femoral artery using 3F introducer sheaths.Materials and MethodsEligibility criteria for this single-center, prospective study included clinically necessary angiography, no coagulopathy or anticoagulant therapy, no hypersensitivity to contrast medium, age >20 years, and written, informed consent. Enrolled patients were assigned to one of three groups (105/group) with the duration of bed rest deceased sequentially. A sheath was inserted by way of the common femoral artery using the Seldinger technique. The first group (level 1) received 3 h of bed rest after the vascular intervention. If no bleeding or hematomas developed, the next group (level 2) received 2.5 h of bed rest. If still no bleeding or hematomas developed, the final group (level 3) received 2 h of bed rest. If any patient had bleeding or hematomas after bed rest, the study was terminated, and the bed rest of the preceding level was considered the optimal duration.ResultsA total of 105 patients were enrolled at level 1 between November 2010 and September 2011. Eight patients were excluded from analysis because cessation of bed rest was delayed. None of the remaining subjects experienced postoperative bleeding; therefore, patient enrollment at level 2 began in September 2011. However, puncture site bleeding occurred in the 52nd patient immediately after cessation of bed rest, necessitating study termination.ConclusionTo prevent bleeding, at least 3 h of postoperative bed rest is recommended for patients undergoing angiography using 3F sheaths

  1. Bone Loss in Space: Shuttle/MIR Experience and Bed Rest Countermeasure Program

    Science.gov (United States)

    Shackelford, L. C.; LeBlanc, A.; Feiveson, A.; Oganov, V.

    1999-01-01

    Loss of bone mineral during space flight was documented in the 1970's Skylab missions. The USSR space program made similar observations in the 1980's. The Institute of Biomedical Problems in Moscow and NASA JSC in 1989 began to collect pre- and post-flight bone mineral density (BMD) using Hologic QDR 1000 DEXA scanners transferred from JSC to Moscow and Star City. DEXA whole body, hip, and lumbar spine scans were performed prior to and during the first week after return from 4- to 6-month missions (plus one 8-month mission and one 14- month mission) on the Mir space station. These data documented the extent and regional nature of bone loss during long duration space flight. Of the 18 cosmonauts participating in this study between 1990 and 1995, seven flew two missions. BMD scans prior to the second flight compared to the first mission preflight scans indicated that recovery was possibly delayed or incomplete. Because of these findings, NASA and IBMP initiated the study "Bone Mineral Loss and Recovery After Shuttle/Mir Flights" in 1995 to evaluate bone recovery during a 3-year post-flight period. All of the 14 participants thus far evaluated lost bone in at least one region of the spine and lower extremities during flight. Of the 14, only one to date has exhibited full return to baseline BNM values in all regions. The current study will continue until the last participant has reached full bone recovery in all regions, has reached a plateau, or until three years after the flight (2001 for the last mission of the program). Bone mineral density losses in space and difficulty in returning to baseline indicate a need for countermeasure development. In late 1996 NASA JSC and Baylor College of Medicine were approved to conduct two countermeasure studies during 17 weeks of bed rest. In 1997 the studies were begun in the bed rest facility established by NASA, Baylor College of Medicine, and The Methodist Hospital in Houston. To date, three bed rest controls, five resistive

  2. Radiodiagnostic errors by X-ray pictures of the chest taken at bed resting patients

    Energy Technology Data Exchange (ETDEWEB)

    Ross, D.; Deininger, H.K.

    1981-03-01

    The roentgenological findings of 383 cases have been compared with the anatomical and pathological diagnosis of the autopsy report. In 29% the radiodiagnosis was incorrect. About 70% of the X-ray examinations had to be carried out succenturiately at bed side in bedridden patients. The error rate of the interpretation of these examinations was higher than in examinations under standardized conditions. Especially, carcinomatous lymphangiosis, miliary tuberculosis and pulmonary embolism can be diagnosed badly in those incomplete X-ray pictures caused by the clinical situation of the bed resting patients. The publication analyses the most common errors in the diagnosis of cardiac and pulmonary diseases, and they will be demonstrated in examples.

  3. Effects of long-duration bed rest on structural compartments of m. soleus in man

    Science.gov (United States)

    Belozerova, I.; Shenkman, B.; Mazin, M.; Leblanc, A.; LeBlanc, A. D. (Principal Investigator)

    2001-01-01

    Magnetic resonance imaging (MRI), histomorphometry and electron microscopy of muscle demonstrate that long-term exposure to actual or simulated weightlessness (including head down bed rest) leads to decreased volume of antigravity muscles in mammals. In muscles interbundle space is occupied by the connective tissue. Rat studies show that hindlimb unloading induces muscle fiber atrophy along with increase in muscle non-fiber connective tissue compartment. Beside that, usually 20% of the muscle fiber volume is comprised by non-contractile (non-myofibrillar) compartment. The aim of the present study was to compare changes in muscle volume, and in muscle fiber size with alterations in myofibrillar apparatus, and in connective tissue compartment in human m. soleus under conditions of 120 day long head down bed rest (HDBR).

  4. Women's experience of hospitalized bed rest during high-risk pregnancy.

    Science.gov (United States)

    Rubarth, Lori Baas; Schoening, Anne M; Cosimano, Amy; Sandhurst, Holly

    2012-01-01

    To describe the lived experience of the hospitalized pregnant woman on bed rest. A qualitative, phenomenological design. Three high-risk antepartum units in the midwestern United States. A self-selected, convenience sample of 11 high-risk pregnant women. Phenomenological study using thematic analysis of completed handwritten journals and/or online blogs. Women described the battles that they fought each day for the lives of their unborn children. Using an imagery of war, three categories emerged: (a) the war within, (b) fighting each battle, and (c) bringing in reinforcements. Women experience many different emotions and stressors during restricted bed rest. A nurse's understanding of this experience is essential to provide adequate care and coping strategies for women at this time. © 2012 AWHONN, the Association of Women's Health, Obstetric and Neonatal Nurses.

  5. Bed Rest is an Analog to Study the Physiological Changes of Spaceflight and to Evaluate Countermeasures

    Science.gov (United States)

    Pfannenstiel, P.; Ottenbacher, M.; Inniss, A.; Ware, D.; Anderson, K.; Stranges, S.; Keith, K.; Cromwell, R.; Neigut. J.; Powell, D.

    2012-01-01

    The UTMB/NASA Flight Analog Research Unit is an inpatient unit with a bionutrition kitchen and unique testing areas for studying subjects subjected to 6 degree head-down complete bed rest for prolonged periods as an analog for zero gravity. Bed rest allows study of physiological changes and performance of functional tasks representative of critical interplanetary mission operations and measures of the efficacy of countermeasures designed to protect against the resulting deleterious effects. METHODS/STUDY POPULATION: Subjects are healthy adults 24-55 years old; 60 75 in tall; body mass index 18.5-30; and bone mineral density normal by DXA scan. Over 100 subjects have been studied in 7 campaigns since 2004. The iRAT countermeasure combines high intensity interval aerobic exercises on alternating days with continuous aerobic exercise. Resistance exercise is performed 3 days per week. Subjects are tested on an integrated suite of functional and interdisciplinary physiological tests before and after 70 days of total bed rest. RESULTS/ANTICIPATED RESULTS: It is anticipated that post-bed rest functional performance will be predicted by a weighted combination of sensorimotor, cardiovascular and muscle physiological factors. Control subjects who do not participate in the exercise countermeasure will have significantly greater decreases in these parameters. DISCUSSION/SIGNIFICANCE OF IMPACT: Astronauts experience alterations in multiple physiological systems due to exposure to the microgravity, leading to disruption in the ability to perform functional tasks after reintroduction to a gravitational environment. Current flight exercise countermeasures are not fully protective of cardiovascular, muscle and bone health. There is a need to refine and optimize countermeasures to mitigate health risks associated with long-term space missions.

  6. Electromyographic evaluation of high-intensity elastic resistance exercises for lower extremity muscles during bed rest

    DEFF Research Database (Denmark)

    Vinstrup, Jonas; Skals, Sebastian; Calatayud, Joaquin

    2017-01-01

    PURPOSE: Prolonged hospital bed rest after severe injury or disease leads to rapid muscle atrophy and strength loss. Therefore, the main aim of this study was to evaluate the efficacy of lower extremity strengthening exercises using elastic resistance that can be performed while lying in a hospit......, the present study has the potential to provide a reference table of exercises to select from when individualizing and progressing strengthening exercises during the early rehabilitation of bedridden individuals....

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

    DEFF Research Database (Denmark)

    Christensen, Niels J; Heer, Martina; Ivanova, Krassimira

    2005-01-01

    We tested the hypothesis that sympathoadrenal activity in humans is low during spaceflight and that this effect can be simulated by head-down bed rest (HDBR). Platelet norepinephrine and epinephrine were measured as indexes of long-term changes in sympathoadrenal activity. Ten normal healthy......, and at least 2 wk after return to Earth. Because of the long half-life of platelet norepinephrine, data obtained early after landing would still reflect the microgravity state. Platelet norepinephrine decreased markedly during HDBR (P

  8. CHANGES IN MENTAL HEALTH AND SATISFACTION WITH LIFE DURING PHYSICAL INACTIVITY INDUCED BY BED REST EXPERIMENT

    Directory of Open Access Journals (Sweden)

    Tjaša Dimec Časar

    2016-01-01

    Full Text Available Simulated weightlessness by bed rest model represents an important method to study the consequences of physical inactivity and sedentarism on the human body. The purpose of the study was to examine the effects of prolonged physical inactivity on psychological distress, depressive symptoms and satisfaction with life of healthy male adults. Participants were ten volunteers, aged between 21 and 28 years who were subjected to a 35-day head-down bed rest. Psychological state of the participants was measured with the General Health Questionnaire (GHQ-12, the Center for Epidemiological Studies Depression Scale (CES-D, and the Satisfaction with Life Scale (SWLS. Participants completed psychological inventories before, during and after the experiment. The results revealed no significant differences in mental health and satisfaction with life of participants following the head-down bed rest, however there was a tendency towards an increase in neurotic and depressive symptoms at the end of the experiment. The obtained results are interpreted in the light of stimulative living conditions in which the experiment was carried out, as well as the amount and quality of social interactions during the period of extended physical inactivity.

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

    Science.gov (United States)

    Aubert, André E.

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Jiexin Liu

    2015-01-01

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

  11. Markers of bone resorption and calcium metabolism are related to dietary intake patterns in male and female bed rest subjects

    Science.gov (United States)

    Smith, Scott M.; Zwart, S. R.; Hargens, A. r.

    2006-01-01

    Dietary potassium and protein intakes predict net endogenous acid production in humans. Intracellular buffers, including exchangeable bone mineral, play a crucial role in balancing chronic acid-base perturbations in the body; subsequently, chronic acid loads can potentially contribute to bone loss. Bone is lost during space flight, and a dietary countermeasure would be desirable for many reasons. We studied the ability of diet protein and potassium to predict levels of bone resorption markers in males and females. Identical twin pairs (8 M, 7 F) were assigned to 2 groups: bed rest (sedentary, SED) or bed rest with supine treadmill exercise in a lower body negative pressure chamber (EX). Diet was controlled for 3 d before and 30 d of bed rest (BR). Urinary Ca, N-telopeptide (NTX), and pyridinium crosslinks (PYD) were measured before and on days 5, 12, 19, and 26 of BR. Data were analyzed by Pearson correlation (Pdietary animal protein/potassium intake was not correlated with NTX before BR for males or females, but they were positively correlated in both groups of males during bed rest. Dietary animal protein/potassium and urine Ca were correlated before and during bed rest for the males, and only during bed rest for the females. Conversely, the ratio of dietary vegetable protein/potassium intake was negatively correlated with urinary calcium during bed rest for the females, but there was no relationship between vegetable protein/potassium intake and bone markers for the males. These data suggest that the ratio of animal protein/potassium intake may affect bone, particularly in bed rest subjects. These data show that the type of protein and gender may be additional factors that modulate the effect of diet on bone metabolism during bed rest. Altering this ratio may help prevent bone loss on Earth and during space flight.

  12. Markers of bone resorption and calcium metabolism are related to dietary intake patterns in male and female bed rest subjects

    Science.gov (United States)

    Smith, Scott M.; Zwart, S. R.; Hargens, A. r.

    2006-01-01

    Dietary potassium and protein intakes predict net endogenous acid production in humans. Intracellular buffers, including exchangeable bone mineral, play a crucial role in balancing chronic acid-base perturbations in the body; subsequently, chronic acid loads can potentially contribute to bone loss. Bone is lost during space flight, and a dietary countermeasure would be desirable for many reasons. We studied the ability of diet protein and potassium to predict levels of bone resorption markers in males and females. Identical twin pairs (8 M, 7 F) were assigned to 2 groups: bed rest (sedentary, SED) or bed rest with supine treadmill exercise in a lower body negative pressure chamber (EX). Diet was controlled for 3 d before and 30 d of bed rest (BR). Urinary Ca, N-telopeptide (NTX), and pyridinium crosslinks (PYD) were measured before and on days 5, 12, 19, and 26 of BR. Data were analyzed by Pearson correlation (P<0.05). The ratio of dietary animal protein/potassium intake was not correlated with NTX before BR for males or females, but they were positively correlated in both groups of males during bed rest. Dietary animal protein/potassium and urine Ca were correlated before and during bed rest for the males, and only during bed rest for the females. Conversely, the ratio of dietary vegetable protein/potassium intake was negatively correlated with urinary calcium during bed rest for the females, but there was no relationship between vegetable protein/potassium intake and bone markers for the males. These data suggest that the ratio of animal protein/potassium intake may affect bone, particularly in bed rest subjects. These data show that the type of protein and gender may be additional factors that modulate the effect of diet on bone metabolism during bed rest. Altering this ratio may help prevent bone loss on Earth and during space flight.

  13. WISE-2005: Integrative cardiovascular responses with LBNP during 60-day bed rest in women

    Science.gov (United States)

    Hughson, R. L.; Kerbeci, P.; Arbeille, P.; Mattar, L.; Shoemaker, J. K.

    2005-08-01

    During 2005, 24 women will take part in the Women International Space-simulation for Exploration (WISE). In this paper we report on the first phase that studied 4 Exercise (EX+LBNP), 4 nutrition (NUT), and 4 no countermeasure control (CON) subjects. The EX+LBNP group completed regular exercise on a treadmill inside LBNP, flywheel resistive exercise and static periods of LBNP, and had recovery days. The NUT group received daily protein supplements. Integrative cardiovascular responses were obtained and here we report data for heart rate during LBNP, blood volume and angiotensin II. LBNP was applied at 0, -10, -20 and -30 mmHg for 2-minutes for each stage. Blood was sampled pre- bed rest and on HDT-60. After 60-days head down bed rest, HR in the CON group increased by 6.1±2.8 bpm at rest and by 20.7±5.0 bpm at -30 mmHg LBNP. The EX+LBNP group had increases of 3.6±5.6 and 11.6±5.4 bpm, while the NUT group HR increased 2.6±3.1 and 9.4±3.6 bpm. The EX+LBNP group had almost no change in blood volume or plasma angiotensin II from pre-bed rest to HDT60, while both the CON and NUT groups had larger increases in plasma volume and almost double concentrations of angiotensin II. These data show a positive effect in the EX+LBNP group on the heart rate response as well as an unexpected possible benefit in the NUT group. Further studies are required to confirm possible cardiovascular benefits of the protein supplement.

  14. Human thermoregulatory function during exercise and immersion after 35 days of horizontal bed-rest and recovery.

    Science.gov (United States)

    Mekjavic, Igor B; Golja, Petra; Tipton, Michael J; Eiken, Ola

    2005-10-01

    The present study evaluated the effect of 35 days of experimental horizontal bed-rest on exercise and immersion thermoregulatory function. Fifteen healthy male volunteers were assigned to either a Control (n = 5) or Bed-rest (n = 10) group. Thermoregulatory function was evaluated during a 30-min bout of submaximal exercise on a cycle ergometer, followed immediately by a 100-min immersion in 28 degrees C water. For the Bed-rest group, exercise and immersion thermoregulatory responses observed post-bed-rest were compared with those after a 5 week supervised active recovery period. In both trials, the absolute work load during the exercise portion of the test was identical. During the exercise and immersion, we recorded skin temperature, rectal temperature, the difference in temperature between the forearm and third digit of the right hand (DeltaT(forearm-fingertip))--an index of skin blood flow, sweating rate from the forehead, oxygen uptake and heart rate at minute intervals. Subjects provided ratings of temperature perception and thermal comfort at 5-min intervals. Exercise thermoregulatory responses after bed-rest and recovery were similar. Subjective ratings of temperature perception and thermal comfort during immersion indicated that subjects perceived similar combinations of Tsk and Tre to be warmer and thermally less uncomfortable after bed-rest. The average (SD) exercise-induced increase in Tre relative to resting values was not significantly different between the Post-bed-rest (0.4 (0.2) degrees C) and Recovery (0.5 (0.2) degrees C) trials. During the post-exercise immersion, the decrease in Tre, relative to resting values, was significantly (P forearm-fingertip) was 5.2 (0.9) degrees C and 5.8 (1.0) degrees C at the end of the post-bed-rest and recovery immersions, respectively. The gain of the shivering response (increase in VO(2) relative to the decrease in Tre; VO(2)/Tre) was 1.19 l min(-1) degrees C(-1) in the Recovery trial, and was significantly

  15. Decreased bed rest post-percutaneous coronary intervention with a 7-French arterial sheath and its effects on vascular complications.

    Science.gov (United States)

    Wentworth, Laura J; Bechtum, Elizabeth L; Hoffman, Jessica G; Kramer, Robert R; Bartel, David C; Slusser, Joshua P; Tilbury, Ralph Thomas

    2018-01-01

    To compare the incidence of femoral access puncture site complications in the control group, who underwent 6 hr of bed rest, with patients in the case group, who underwent 4 hr of bed rest. The ideal bed rest length after percutaneous coronary intervention with a 7-French arterial sheath has been investigated by nursing practice. However, in this larger-sheath-size group, best practices have not been determined, and bed rest time continues to vary markedly among institutions. Retrospective study. Data were retrieved from the National Cardiovascular Data Registry and electronic health records in this retrospective study. Sample size was 401 patients: 152 case patients with 4-hr bed rest and 249 controls with 6-hr bed rest. Case group data were obtained from 20 May 2013-31 December 2014; and control group data, 15 June 2011-20 May 2013. National Cardiovascular Data Registry event rates were generally low in both groups: Only three patients in each group had a bleeding event within 72 hr (2% vs. 1%) and no patient and only two controls had arteriovenous fistula (0% vs. 1%). Complications documented in the electronic health records with institutional femoral access puncture site complication definitions identified bleeding at the access site in eight case patients (5%) and nine controls (4%). Haematoma at the access site occurred in 21 case patients (14%) and 25 controls (10%). The practice change of decreasing bed rest from 6-4 hr for patients with 7-French arterial sheaths post-percutaneous coronary intervention was associated with no significant change in femoral access puncture site complications in either National Cardiovascular Data Registry data or institutional electronic health records data. This introduces expanded evidence of safety in decreasing bed rest length in larger (7-French) arterial sheaths post-percutaneous coronary intervention. © 2017 John Wiley & Sons Ltd.

  16. THE EFFECTS OF PROLONGED PHYSICAL INACTIVITY INDUCED BY BED REST ON COGNITIVE FUNCTIONING IN HEALTHY MALE PARTICIPANTS

    Directory of Open Access Journals (Sweden)

    Petra Dolenc

    2013-06-01

    Full Text Available A growing body of scientific evidence indicates that physical activity beneficially influences cognitive functioning. Less thoroughly investigated are the cognitive outcomes of reduced physical activity levels. The purpose of the study was to determine the effects of prolonged physical inactivity induced by bed rest on the participant’s cognitive functioning. Bed rest is a well-accepted method by which an acute stage of human adaptation to weightlessness in space flights is simulated, as well as an important model to study the consequences of extreme physical inactivity in humans. The subjects participating in the study consisted of fifteen healthy males aged between 19 and 65 years who were exposed to 14-day horizontal bed rest in a strict hospital environment. To assess the cognitive functions of the participants, a neuropsychological test battery was administered before and after the bed rest experiment. There was no significant impairment in cognitive performance after the 14-day bed rest on all tests, except in the measurements of delayed recall in the group of older adults. The results suggest that cognitive functions remained relatively stable during the period of physical immobilization. The obtained results have been discussed taking the possible contributing factors into account such as the practice effect, the relatively short duration of bed rest, and the choice of the cognitive measures administered. The study also provides evidence that favourable living and psychosocial conditions can protect one against cognitive decline in the case of extreme physical inactivity.

  17. Radiodiagnostic errors by X-ray pictures of the chest taken at bed resting patients

    International Nuclear Information System (INIS)

    Ross, D.; Deininger, H.K.

    1981-01-01

    The roentgenological findings of 383 cases have been compared with the anatomical and pathological diagnosis of the autopsy report. In 29% the radiodiagnosis was incorrect. About 70% of the X-ray examinations had to be carried out succenturiately at bed side in bedridden patients. The error rate of the interpretation of these examinations was higher than in examinations under standardized conditions. Especially, carcinomatous lymphangiosis, miliary tuberculosis and pulmonary embolism can be diagnosed badly in those incomplete X-ray pictures caused by the clinical situation of the bed resting patients. The publication analyses the most common errors in the diagnosis of cardiac and pulmonary diseases, and they will be demonstrated in examples. (orig.) [de

  18. Dietary acid load and bone turnover during long-duration spaceflight and bed rest.

    Science.gov (United States)

    Zwart, Sara R; Rice, Barbara L; Dlouhy, Holly; Shackelford, Linda C; Heer, Martina; Koslovsky, Matthew D; Smith, Scott M

    2018-05-01

    Bed rest studies document that a lower dietary acid load is associated with lower bone resorption. We tested the effect of dietary acid load on bone metabolism during spaceflight. Controlled 4-d diets with a high or low animal protein-to-potassium (APro:K) ratio (High and Low diets, respectively) were given to 17 astronauts before and during spaceflight. Each astronaut had 1 High and 1 Low diet session before flight and 2 High and 2 Low sessions during flight, in addition to a 4-d session around flight day 30 (FD30), when crew members were to consume their typical in-flight intake. At the end of each session, blood and urine samples were collected. Calcium, total protein, energy, and sodium were maintained in each crew member's preflight and in-flight controlled diets. Relative to preflight values, N-telopeptide (NTX) and urinary calcium were higher during flight, and bone-specific alkaline phosphatase (BSAP) was higher toward the end of flight. The High and Low diets did not affect NTX, BSAP, or urinary calcium. Dietary sulfur and age were significantly associated with changes in NTX. Dietary sodium and flight day were significantly associated with urinary calcium during flight. The net endogenous acid production (NEAP) estimated from the typical dietary intake at FD30 was associated with loss of bone mineral content in the lumbar spine after the mission. The results were compared with data from a 70-d bed rest study, in which control (but not exercising) subjects' APro:K was associated with higher NTX during bed rest. Long-term lowering of NEAP by increasing vegetable and fruit intake may protect against changes in loss of bone mineral content during spaceflight when adequate calcium is consumed, particularly if resistive exercise is not being performed. This trial was registered at clinicaltrials.gov as NCT01713634.

  19. Excretion of Zinc and Copper Increases in Men during 3 Weeks of Bed Rest, with or without Artificial Gravity.

    Science.gov (United States)

    Heacox, Hayley N; Gillman, Patricia L; Zwart, Sara R; Smith, Scott M

    2017-06-01

    Background: Zinc and copper have many physiologic functions and little or no functional storage capability, so persistent losses of either element present health concerns, especially during extended-duration space missions. Objectives: We evaluated the effects of short-term bed rest (BR), a spaceflight analog, on copper and zinc metabolism to better understand the role of these nutrients in human adaptation to (simulated) spaceflight. We also investigated the effect of artificial gravity on copper and zinc homeostasis. Methods: Zinc and copper balances were studied in 15 men [mean ± SD age: 29 ± 3 y; body mass index (in kg/m 2 ): 26.4 ± 2.2] before, during, and after 21 d of head-down tilt BR, during which 8 of the participants were subjected to artificial gravity (AG) by centrifugation for 1 h/d. Control subjects were transferred onto the centrifuge but were not exposed to centrifugation. The study was conducted in a metabolic ward; all urine and feces were collected. Data were analyzed by 2-factor repeated-measures ANOVA. Results: Urinary zinc excretion values for control and AG groups were 33% and 14%, respectively, higher during BR than before BR, and fecal zinc excretion values for control and AG groups were 36% and 19%, respectively, higher during BR, resulting in 67% and 82% lower net zinc balances for controls and AG, respectively (both P zinc by men during BR suggests that their absorption of these minerals from the diet was reduced, secondary to the release of minerals from bone and muscle. These findings highlight the importance of determining dietary requirements for astronauts on space missions and ensuring provision and intake of all nutrients. © 2017 American Society for Nutrition.

  20. Physiological responses of women to simulated weightlessness: A review of the first female bed-rest study

    Science.gov (United States)

    Sandler, H.; Winter, D. L.

    1978-01-01

    Subjects were exposed to centrifugation, to lower body negative pressure (LBNP), and to exericse stress both before and after bed rest. Areas studied were centrifugation tolerance, fluid electrolyte changes and hematology, tolerance to LBNP, physical working capacity, biochemistries, blood fibrinolytic activity, female metabolic and hormonal responses, circadian alterations, and gynecology. Results were compared with the responses observed in similarly bed-rested male subjects. The bed-rested females showed deconditioning responses similar to those of the males, although with some differences. Results indicate that women are capable of coping with exposure to weightlessness and, moreover, that they may be more sensitive subjects for evaluating countermeasures to weightlessness and developing criteria for assessing applicants for shuttle voyages.

  1. Weightlessness and Cardiac Rhythm Disorders: Current Knowledge from Space Flight and Bed-Rest Studies

    International Nuclear Information System (INIS)

    Caiani, Enrico G.; Martin-Yebra, Alba; Landreani, Federica; Bolea, Juan; Laguna, Pablo; Vaïda, Pierre

    2016-01-01

    Isolated episodes of heart rhythm disorders have been reported during 40 years of space flight, triggering research to evaluate the risk of developing life-threatening arrhythmias induced by prolonged exposure to weightlessness. In fact, these events could compromise astronaut performance during exploratory missions, as well as pose at risk the astronaut health, due to limited options of care on board the International Space Station. Starting from original observations, this mini review will explore the latest research in this field, considering results obtained both during space flight and on Earth, the latter by simulating long-term exposure to microgravity by head-down bed rest maneuver in order to elicit cardiovascular deconditioning on normal volunteers.

  2. Prolonged bed rest decreases skeletal muscle and whole body protein synthesis

    Science.gov (United States)

    Ferrando, A. A.; Lane, H. W.; Stuart, C. A.; Davis-Street, J.; Wolfe, R. R.

    1996-01-01

    We sought to determine the extent to which the loss of lean body mass and nitrogen during inactivity was due to alterations in skeletal muscle protein metabolism. Six male subjects were studied during 7 days of diet stabilization and after 14 days of stimulated microgravity (-6 degrees bed rest). Nitrogen balance became more negative (P protein synthesis (PS; P protein also decreased by 46% (P protein breakdown and inward transport. Whole body protein synthesis determined by [15N]alanine ingestion on six subjects also revealed a 14% decrease (P protein breakdown change significantly. These results indicate that the loss of body protein with inactivity is predominantly due to a decrease in muscle PS and that this decrease is reflected in both whole body and skeletal muscle measures.

  3. Weightlessness and Cardiac Rhythm Disorders: Current Knowledge from Space Flight and Bed-Rest Studies

    Energy Technology Data Exchange (ETDEWEB)

    Caiani, Enrico G. [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milan (Italy); Martin-Yebra, Alba [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milan (Italy); Instituto de Investigación en Ingeniería de Aragón (I3A), Universidad de Zaragoza, Zaragoza (Spain); Landreani, Federica [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milan (Italy); Bolea, Juan; Laguna, Pablo [Instituto de Investigación en Ingeniería de Aragón (I3A), Universidad de Zaragoza, Zaragoza (Spain); Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina, Zaragoza (Spain); Vaïda, Pierre, E-mail: enrico.caiani@polimi.it [École Nationale Supérieure de Cognitique, Institut Polytechnique de Bordeaux, Université de Bordeaux, Bordeaux (France)

    2016-08-23

    Isolated episodes of heart rhythm disorders have been reported during 40 years of space flight, triggering research to evaluate the risk of developing life-threatening arrhythmias induced by prolonged exposure to weightlessness. In fact, these events could compromise astronaut performance during exploratory missions, as well as pose at risk the astronaut health, due to limited options of care on board the International Space Station. Starting from original observations, this mini review will explore the latest research in this field, considering results obtained both during space flight and on Earth, the latter by simulating long-term exposure to microgravity by head-down bed rest maneuver in order to elicit cardiovascular deconditioning on normal volunteers.

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

    Science.gov (United States)

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

    2012-01-01

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

  5. Markers of bone resorption and calcium metabolism are related to dietary intake patterns in male and female bed rest subjects

    Science.gov (United States)

    Smith, Scott M.; Zwart, S. R.; Hargens, A. r.

    2006-01-01

    Dietary potassium and protein intakes predict net endogenous acid production in humans. Intracellular buffers, including exchangeable bone mineral, play a crucial role in balancing chronic acid-base perturbations in the body; subsequently, chronic acid loads can potentially contribute to bone loss. Bone is lost during space flight, and a dietary countermeasure would be desirable for many reasons. We studied the ability of diet protein and potassium to predict levels of bone resorption markers in males and females. Identical twin pairs (8 M, 7 F) were assigned to 2 groups: bed rest (sedentary, SED) or bed rest with supine treadmill exercise in a lower body negative pressure chamber (EX). Diet was controlled for 3 d before and 30 d of bed rest (BR). Urinary Ca, N-telopeptide (NTX), and pyridinium crosslinks (PYD) were measured before and on days 5, 12, 19, and 26 of BR. Data were analyzed by Pearson correlation (Pdiet on bone metabolism during bed rest. Altering this ratio may help prevent bone loss on Earth and during space flight.

  6. Effects of bed-rest on urea and creatinine: correlation with changes in fat-free mass.

    Science.gov (United States)

    Bilancio, Giancarlo; Lombardi, Cinzia; Pisot, Rado; De Santo, Natale G; Cavallo, Pierpaolo; Cirillo, Massimo

    2014-01-01

    Bed-rest experiments are designed for investigation on catabolic effects of hypokinetic conditions and/or for microgravity simulation in on-ground aerospace research. Bed-rest effects include a reduction in fat-free mass and muscle mass. Urea and creatinine are catabolites of endogenous protein and of muscular energetic metabolism which are excreted mainly by the kidney. The study investigated on urea, creatinine, and kidney function during bed-rest. Twenty healthy young men underwent a 7-day adaptation period (day-6 to day-0) and a 35-day bed-rest experiment (day1 to day35) during normocaloric diet. Urine were collected from day-3 to day0 (baseline) and from day1 to day35. Blood samples and anthropometrical data were collected at day0 (baseline) and bed-rest days 7, 14, 21, 28, and 35. Bed-rest reduced plasma volume, weight, fat-free mass, and muscle mass (Pcreatinine, and no change in urinary creatinine. The overall integral of changes from day0 to day35 was on average +101.7 mg/dL for plasma urea (95%CI = +43.4/+159.9), +82.2 g/24 h for urinary urea (95%CI = +55.8/+108.7), -2.5 mg/dL for plasma creatinine (95%CI = -3.1/-1.9). Bed-rest reduced plasma cistatyn C also, which was used as mass-independent marker of glomerular filtration rate (-13.1%, P<0.05). Correlations with final reduction in fat-free mass and muscle mass were significant for the overall integral of changes in urinary urea from day0 to day35 (R = 0.706, P<0.001) and for early changes in urinary urea and plasma urea from day0 to day7 (R = 0.566, P = 0.009 and R = 0.715, P<0.001, respectively). Study results shows that urea is a marker of catabolic conditions secondary to hypokinetic conditions.

  7. The Artificial Gravity Bed Rest Pilot Project: Effects on Knee Extensor and Plantar Flexor Muscle Groups

    Science.gov (United States)

    Caiozzo, V. J.; Haddad, F.; Lee, S.; Baker, M.; Baldwin, K. M.

    2007-01-01

    The goal of this project was to examine the effects of artificial gravity (2.5 g) on skeletal muscle strength and key anabolic/catabolic markers known to regulate muscle mass. Two groups of subjects were selected for study: 1) a 21 day-bed rest (BR) control (C) group (N=7); and 2) an AG group (N=8), which was exposed to 21 days of bed-rest plus daily 1 hr exposures to AG (2.5 g). This particular experiment was part of an integrated AG Pilot Project sponsored by NASA/Johnson Space Center. The in vivo torque-velocity relationships of the knee extensors and plantar flexors of the ankle were determined pre and post treatment. Also, pre- and post treatment biopsy samples were obtained from both the vastus lateralis and soleus muscles and were used, in part, for a series of analyses on gene expression (mRNA abundance) of key factors implicated in the anabolic versus catabolic state of the muscle. Post/Pre toque-velocity determinations revealed greater decrements in knee extensor performance in the C versus AG group (P less than 0.04). The plantar flexor muscle group of the AG subjects actually demonstrated a net gain in torque-velocity relationship; whereas, in the C group the overall post/pre responses declined (AG vs C; P less than 0.001). Measurements of muscle fiber cross-sectional area (for both muscles) demonstrated a loss of approx. 20% in the C group while no losses were evident in the AG group. RT-PCR analyses of muscle biopsy specimens demonstrated that markers of growth and cytoskeletal integrity (IGF-1, IGF-1 BP4, mechano growth factor, total RNA, and pro-collagen 3a) were higher in the AG group, whereas catabolic markers (myostatin and atrogen) were elevated in the C group. Importantly, these patterns were seen in both muscles. Based on these observations we conclude that paradigms of AG have the potential to maintain the functional, biochemical, and structural homeostasis of skeletal muscle in the face of chronic unloading states. These findings also

  8. Effects of Artificial Gravity and Bed Rest on Spatial Orientation and Balance Control

    Science.gov (United States)

    Paloski, William H.; Moore, S. T.; Feiveson, A. H.; Taylor, L. C.

    2007-01-01

    While the vestibular system should be well-adapted to bed rest (a condition it experiences approximately 8/24 hrs each day), questions remain regarding the degree to which repeated exposures to the unusual gravito-inertial force environment of a short-radius centrifuge might affect central processing of vestibular information used in spatial orientation and balance control. Should these functions be impaired by intermittent AG, its feasibility as a counter-measure would be diminished. We, therefore, examined the effects of AG on spatial orientation and balance control in 15 male volunteers before and after 21 days of 6 HDT bed rest (BR). Eight of the subjects were treated with daily 1hr AG exposures (2.5g at the feet; 1.0g at the heart) aboard a short radius (3m) centrifuge, while the other seven served as controls (C). Spatial orientation was assessed by measures of ocular counter-rolling (OCR; rotation of the eye about the line of sight, an otolith-mediated reflex) and subjective visual vertical (SVV; perception of the spatial upright). Both OCR and SVV measurements were made with the subject upright, lying on their left sides, and lying on their right sides. OCR was measured from binocular eye orientation recordings made while the subjects fixated for 10s on a point target directly in front of the face at a distance of 1 m. SVV was assessed by asking subjects (in the dark) to adjust to upright (using a handheld controller) the orientation of a luminous bar randomly perturbed (15) to either side of the vertical meridian. Balance control performance was assessed using a computerized dynamic posturography (CDP) protocol similar to that currently required for all returning crew members. During each session, the subjects completed a combination of trials of sensory organization test (SOT) 2 (eyes closed, fixed platform) and SOT 5 (eyes closed, sway-referenced platform) with and without static and dynamic pitch plane head movements (plus or minus 20 deg., dynamic

  9. Bed rest versus early ambulation with standard anticoagulation in the management of deep vein thrombosis: a meta-analysis.

    Directory of Open Access Journals (Sweden)

    Zhenlei Liu

    Full Text Available Bed rest has been considered as the cornerstone of management of deep vein thrombosis (DVT for a long time, though it is not evidence-base, and there is growing evidence favoring early ambulation.Electronic databases including Medline, PubMed, Cochrane Library and three Chinese databases were searched with key words of "deep vein thrombosis", "pulmonary embolism", "venous thrombosis", "bed rest", "immobilization", "mobilization" and "ambulation". We considered randomized controlled trials, prospective or retrospective cohort studies that compared the outcomes of acute DVT patients managed with early ambulation versus bed rest, in addition to standard anticoagulation. Meta-analysis pertaining to the incidence of new pulmonary embolism (PE, progression of DVT, and DVT related deaths were conducted, as well as the extent of remission of pain and edema.13 studies were included with a total of 3269 patients. Compared to bed rest, early ambulation was not associated with a higher incidence of new PE, progression of DVT, or DVT related deaths (RD -0.03, 95% CI -0.05∼ -0.02; Z = 1.24, p = 0.22; random effect model, Tau2 = 0.01. Moreover, if the patients suffered moderate or severe pain initially, early ambulation was related to a better outcome, with respect to remission of acute pain in the affected limb (SMD 0.42, 95%CI 0.09∼0.74; Z = 2.52, p = 0.01; random effect model, Tau2 = 0.04. Meta-analysis of alleviation of edema cannot elicit a solid conclusion because of significant heterogeneity among the few studies.Compared to bed rest, early ambulation of acute DVT patients with anticoagulation was not associated with a higher incidence of new PE, progression of DVT, and DVT related deaths. Furthermore, for the patients suffered moderate or severe pain initially, a better outcome can be seen in early ambulation group, regarding to the remission of acute pain in the affected limb.

  10. Evaluation of potentially significant increase of lead in the blood during long-term bed rest and space flight.

    Science.gov (United States)

    Kondrashov, Vladislav; Rothenberg, Stephen J; Chettle, David; Zerwekh, Joseph

    2005-02-01

    We address a gap in the knowledge of lead turnover under conditions of prolonged bed rest and microgravity by developing a quantitative model of the amount of lead returned to blood circulation from bone. We offer the hypothesis that skeletal unloading, such as typically occurs during extended bed rest or microgravity, will result in bone lead being released to the blood, as has already been demonstrated in the case of calcium. We use initial bone lead concentrations to develop predictive models of blood lead elevation. Our theoretical calculations with typical bone lead loads measured in today's 40-60-year-old generation, suggest that the estimated blood lead concentrations in long duration (e.g., 100 days) space flight could average between 20 and 40 microg dl(-1), a range with well-established toxic effects. For a similar duration of bed rest, estimated blood lead concentration could be as high as 10-20 microg dl(-1), which is a level of concern, particularly if we consider females of childbearing age. The preliminary experimental results were obtained under multi-institutional collaborations, with the main outcome received from an on-going bed rest study, Prevention of Microgravity-Induced Stone Risk by KMgCitrate, conducted at the General Clinical Research Center (GCRC) of the University of Texas Southwestern Medical Center, Dallas. Based on theoretical modeling and some preliminary experimental results, this concept may have important clinical implications by allowing prediction of the magnitude of blood lead elevation, thereby establishing the means to prevent lead toxicity during long duration space flight of astronauts and in conditions of prolonged bed rest such as complicated pregnancy, spinal cord injury induced paralysis and comatose patients.

  11. High-Intensity Jump Training Is Tolerated during 60 Days of Bed Rest and Is Very Effective in Preserving Leg Power and Lean Body Mass: An Overview of the Cologne RSL Study.

    Science.gov (United States)

    Kramer, Andreas; Kümmel, Jakob; Mulder, Edwin; Gollhofer, Albert; Frings-Meuthen, Petra; Gruber, Markus

    2017-01-01

    Space agencies are looking for effective and efficient countermeasures for the degrading effects of weightlessness on the human body. The aim of this study was to assess the effects of a novel jump exercise countermeasure during bed rest on vitals, body mass, body composition, and jump performance. 23 male participants (29±6 years, 181±6 cm, 77±7 kg) were confined to a bed rest facility for 90 days: a 15-day ambulatory measurement phase, a 60-day six-degree head-down-tilt bed rest phase (HDT), and a 15-day ambulatory recovery phase. Participants were randomly allocated to the jump training group (JUMP, n = 12) or the control group (CTRL, n = 11). A typical training session consisted of 4x10 countermovement jumps and 2x10 hops in a sledge jump system. The training group had to complete 5-6 sessions per week. Peak force for the reactive hops (3.6±0.4 kN) as well as jump height (35±4 cm) and peak power (3.1±0.2 kW) for the countermovement jumps could be maintained over the 60 days of HDT. Lean body mass decreased in CTRL but not in JUMP (-1.6±1.9 kg and 0±1.0 kg, respectively, interaction effect p = 0.03). Resting heart rate during recovery was significantly increased for CTRL but not for JUMP (interaction effect pjump training and maintained high peak forces and high power output during 60 days of bed rest. The countermeasure was effective in preserving lean body mass and partly preventing cardiac deconditioning with only several minutes of training per day.

  12. High-Intensity Jump Training Is Tolerated during 60 Days of Bed Rest and Is Very Effective in Preserving Leg Power and Lean Body Mass: An Overview of the Cologne RSL Study.

    Directory of Open Access Journals (Sweden)

    Andreas Kramer

    Full Text Available Space agencies are looking for effective and efficient countermeasures for the degrading effects of weightlessness on the human body. The aim of this study was to assess the effects of a novel jump exercise countermeasure during bed rest on vitals, body mass, body composition, and jump performance.23 male participants (29±6 years, 181±6 cm, 77±7 kg were confined to a bed rest facility for 90 days: a 15-day ambulatory measurement phase, a 60-day six-degree head-down-tilt bed rest phase (HDT, and a 15-day ambulatory recovery phase. Participants were randomly allocated to the jump training group (JUMP, n = 12 or the control group (CTRL, n = 11. A typical training session consisted of 4x10 countermovement jumps and 2x10 hops in a sledge jump system. The training group had to complete 5-6 sessions per week.Peak force for the reactive hops (3.6±0.4 kN as well as jump height (35±4 cm and peak power (3.1±0.2 kW for the countermovement jumps could be maintained over the 60 days of HDT. Lean body mass decreased in CTRL but not in JUMP (-1.6±1.9 kg and 0±1.0 kg, respectively, interaction effect p = 0.03. Resting heart rate during recovery was significantly increased for CTRL but not for JUMP (interaction effect p<0.001.Participants tolerated the near-daily high-intensity jump training and maintained high peak forces and high power output during 60 days of bed rest. The countermeasure was effective in preserving lean body mass and partly preventing cardiac deconditioning with only several minutes of training per day.

  13. Age-related differences in lean mass, protein synthesis and skeletal muscle markers of proteolysis after bed rest and exercise rehabilitation.

    Science.gov (United States)

    Tanner, Ruth E; Brunker, Lucille B; Agergaard, Jakob; Barrows, Katherine M; Briggs, Robert A; Kwon, Oh Sung; Young, Laura M; Hopkins, Paul N; Volpi, Elena; Marcus, Robin L; LaStayo, Paul C; Drummond, Micah J

    2015-09-15

    Bed rest-induced muscle loss and impaired muscle recovery may contribute to age-related sarcopenia. It is unknown if there are age-related differences in muscle mass and muscle anabolic and catabolic responses to bed rest. A secondary objective was to determine if rehabilitation could reverse bed rest responses. Nine older and fourteen young adults participated in a 5-day bed rest challenge (BED REST). This was followed by 8 weeks of high intensity resistance exercise (REHAB). Leg lean mass (via dual-energy X-ray absorptiometry; DXA) and strength were determined. Muscle biopsies were collected during a constant stable isotope infusion in the postabsorptive state and after essential amino acid (EAA) ingestion on three occasions: before (PRE), after bed rest and after rehabilitation. Samples were assessed for protein synthesis, mTORC1 signalling, REDD1/2 expression and molecular markers related to muscle proteolysis (MURF1, MAFBX, AMPKα, LC3II/I, Beclin1). We found that leg lean mass and strength decreased in older but not younger adults after bedrest (P protein synthesis increased before bed rest in both age groups (P protein synthesis rates and increased MAFBX mRNA, p-AMPKα and the LC3II/I ratio (P protein synthesis and a marginal increase in proteolytic markers. Finally, rehabilitation restored bed rest-induced deficits in lean mass and strength in older adults. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

  14. Changes of cytokines during a spaceflight analog--a 45-day head-down bed rest.

    Directory of Open Access Journals (Sweden)

    Xi Xu

    Full Text Available Spaceflight is associated with deregulation in the immune system. Head-down bed rest (HDBR at -6° is believed to be the most practical model for examining multi-system responses to microgravity in humans during spaceflight. In the present study, a 45-day HDBR was performed to investigate the alterations in human immune cell distributions and their functions in response to various stimuli. The effect of countermeasure, Rhodiola rosea (RR treatment, was also examined. A significant decrease of interferon-γ (IFN-γ and interleukin-17 (IL-17 productions by activated T cells, increase of IL-1β and IL-18 by activated B and myeloid cells were observed during HDBR. The upregulation of serum cortisol was correlated with the changes of IL-1 family cytokines. In addition, a significant increase of memory T and B cell and regulatory T cells (Treg were also detected. The uptake of RR further decreased IFN-γ level and slowed down the upregulation of IL-1 family cytokines. These data suggest that for prolonged HDBR and spaceflight, the decreased protective T cell immunity and enhanced proinflammatory cytokines should be closely monitored. The treatment with RR may play an important role in suppressing proinflammatory cytokines but not in boosting protective T cell immunity.

  15. Effects of age and inactivity due to prolonged bed rest on atrophy of trunk muscles.

    Science.gov (United States)

    Ikezoe, Tome; Mori, Natsuko; Nakamura, Masatoshi; Ichihashi, Noriaki

    2012-01-01

    This study investigated the effects of age and inactivity due to being chronically bedridden on atrophy of trunk muscles. The subjects comprised 33 young women (young group) and 41 elderly women who resided in nursing homes or chronic care institutions. The elderly subjects were divided into two groups: independent elderly group who were able to perform activities of daily living involving walking independently (n = 28) and dependent elderly group who were chronically bedridden (n = 13). The thickness of the following six trunk muscles was measured by B-mode ultrasound: the rectus abdominis, external oblique, internal oblique, transversus abdominis, thoracic erector spinae (longissimus) and lumbar multifidus muscles. All muscles except for the transversus abdominis and lumbar multifidus muscles were significantly thinner in the independent elderly group compared with those in the young group. The thicknesses of all muscles in the dependent elderly group was significantly smaller than that in the young group, whereas there were no differences between the dependent elderly and independent elderly groups in the muscle thicknesses of the rectus abdominis and internal oblique muscles. In conclusion, our results suggest that: (1) age-related atrophy compared with young women was less in the deep antigravity trunk muscles than the superficial muscles in the independent elderly women; (2) atrophy associated with chronic bed rest was more marked in the antigravity muscles, such as the back and transversus abdominis.

  16. Changes of Cytokines during a Spaceflight Analog - a 45-Day Head-Down Bed Rest

    Science.gov (United States)

    Zhang, Shusong; Pang, Xuewen; Liu, Hongju; Li, Li; Sun, Xiuyuan; Zhang, Yu; Wu, Hounan; Chen, Xiaoping; Ge, Qing

    2013-01-01

    Spaceflight is associated with deregulation in the immune system. Head-down bed rest (HDBR) at -6° is believed to be the most practical model for examining multi-system responses to microgravity in humans during spaceflight. In the present study, a 45-day HDBR was performed to investigate the alterations in human immune cell distributions and their functions in response to various stimuli. The effect of countermeasure, Rhodiola rosea (RR) treatment, was also examined. A significant decrease of interferon-γ (IFN-γ) and interleukin-17 (IL-17) productions by activated T cells, increase of IL-1β and IL-18 by activated B and myeloid cells were observed during HDBR. The upregulation of serum cortisol was correlated with the changes of IL-1 family cytokines. In addition, a significant increase of memory T and B cell and regulatory T cells (Treg) were also detected. The uptake of RR further decreased IFN-γ level and slowed down the upregulation of IL-1 family cytokines. These data suggest that for prolonged HDBR and spaceflight, the decreased protective T cell immunity and enhanced proinflammatory cytokines should be closely monitored. The treatment with RR may play an important role in suppressing proinflammatory cytokines but not in boosting protective T cell immunity. PMID:24143230

  17. Turning the tide: comparison of tidal flow by periodic sea level fluctuation and by periodic bed tilting in scaled landscape experiments of estuaries

    Science.gov (United States)

    Kleinhans, Maarten G.; van der Vegt, Maarten; Leuven, Jasper; Braat, Lisanne; Markies, Henk; Simmelink, Arjan; Roosendaal, Chris; van Eijk, Arjan; Vrijbergen, Paul; van Maarseveen, Marcel

    2017-11-01

    Analogue models or scale experiments of estuaries and short tidal basins are notoriously difficult to create in the laboratory because of the difficulty to obtain currents strong enough to transport sand. Our recently discovered method to drive tidal currents by periodically tilting the entire flume leads to intense sediment transport in both the ebb and flood phase, causing dynamic channel and shoal patterns. However, it remains unclear whether tilting produces periodic flows with characteristic tidal properties that are sufficiently similar to those in nature for the purpose of landscape experiments. Moreover, it is not well understood why the flows driven by periodic sea level fluctuation, as in nature, are not sufficient for morphodynamic experiments. Here we compare for the first time the tidal currents driven by sea level fluctuations and by tilting. Experiments were run in a 20 × 3 m straight flume, the Metronome, for a range of tilting periods and with one or two boundaries open at constant head with free inflow and outflow. Also, experiments were run with flow driven by periodic sea level fluctuations. We recorded surface flow velocity along the flume with particle imaging velocimetry and measured water levels along the flume. We compared the results to a one-dimensional model with shallow flow equations for a rough bed, which was tested on the experiments and applied to a range of length scales bridging small experiments and large estuaries. We found that the Reynolds method results in negligible flows along the flume except for the first few metres, whereas flume tilting results in nearly uniform reversing flow velocities along the entire flume that are strong enough to move sand. Furthermore, tidal excursion length relative to basin length and the dominance of friction over inertia is similar in tidal experiments and reality. The sediment mobility converges between the Reynolds method and tilting for flumes hundreds of metres long, which is impractical

  18. Turning the tide: comparison of tidal flow by periodic sea level fluctuation and by periodic bed tilting in scaled landscape experiments of estuaries

    Directory of Open Access Journals (Sweden)

    M. G. Kleinhans

    2017-11-01

    Full Text Available Analogue models or scale experiments of estuaries and short tidal basins are notoriously difficult to create in the laboratory because of the difficulty to obtain currents strong enough to transport sand. Our recently discovered method to drive tidal currents by periodically tilting the entire flume leads to intense sediment transport in both the ebb and flood phase, causing dynamic channel and shoal patterns. However, it remains unclear whether tilting produces periodic flows with characteristic tidal properties that are sufficiently similar to those in nature for the purpose of landscape experiments. Moreover, it is not well understood why the flows driven by periodic sea level fluctuation, as in nature, are not sufficient for morphodynamic experiments. Here we compare for the first time the tidal currents driven by sea level fluctuations and by tilting. Experiments were run in a 20  ×  3 m straight flume, the Metronome, for a range of tilting periods and with one or two boundaries open at constant head with free inflow and outflow. Also, experiments were run with flow driven by periodic sea level fluctuations. We recorded surface flow velocity along the flume with particle imaging velocimetry and measured water levels along the flume. We compared the results to a one-dimensional model with shallow flow equations for a rough bed, which was tested on the experiments and applied to a range of length scales bridging small experiments and large estuaries. We found that the Reynolds method results in negligible flows along the flume except for the first few metres, whereas flume tilting results in nearly uniform reversing flow velocities along the entire flume that are strong enough to move sand. Furthermore, tidal excursion length relative to basin length and the dominance of friction over inertia is similar in tidal experiments and reality. The sediment mobility converges between the Reynolds method and tilting for flumes hundreds of

  19. Muscle Adaptations Following Short-Duration Bed Rest with Integrated Resistance, Interval, and Aerobic Exercise

    Science.gov (United States)

    Hackney, Kyle J.; Scott, Jessica M.; Buxton, Roxanne; Redd-Goetchius, Elizabeth; Crowell, J. Brent; Everett, Meghan E.; Wickwire, Jason; Ryder, Jeffrey W.; Bloomberg, Jacob J.; Ploutz-Snyder, Lori L.

    2011-01-01

    Unloading of the musculoskeletal system during space flight results in deconditioning that may impair mission-related task performance in astronauts. Exercise countermeasures have been frequently tested during bed rest (BR) and limb suspension; however, high-intensity, short-duration exercise prescriptions have not been fully explored. PURPOSE: To determine if a high intensity resistance, interval, and aerobic exercise program could protect against muscle atrophy and dysfunction when performed during short duration BR. METHODS: Nine subjects (1 female, 8 male) performed a combination of supine exercises during 2 weeks of horizontal BR. Resistance exercise (3 d / wk) consisted of squat, leg press, hamstring curl, and heel raise exercises (3 sets, 12 repetitions). Aerobic (6 d / wk) sessions alternated continuous (75% VO2 peak) and interval exercise (30 s, 2 min, and 4 min) and were completed on a supine cycle ergometer and vertical treadmill, respectively. Muscle volumes of the upper leg were calculated pre, mid, and post-BR using magnetic resonance imaging. Maximal isometric force (MIF), rate of force development (RFD), and peak power of the lower body extensors were measured twice before BR (averaged to represent pre) and once post BR. ANOVA with repeated measures and a priori planned contrasts were used to test for differences. RESULTS: There were no changes to quadriceps, hamstring, and adductor muscle volumes at mid and post BR time points compared to pre BR (Table 1). Peak power increased significantly from 1614 +/- 372 W to 1739 +/- 359 W post BR (+7.7%, p = 0.035). Neither MIF (pre: 1676 +/- 320 N vs. post: 1711 +/- 250 N, +2.1%, p = 0.333) nor RFD (pre: 7534 +/- 1265 N/ms vs. post: 6951 +/- 1241 N/ms, -7.7%, p = 0.136) were significantly impaired post BR.

  20. Individual Variability in Aerobic Fitness Adaptations to 70-d of Bed Rest and Exercise Training

    Science.gov (United States)

    Downs, Meghan; Buxton, Roxanne; Goetchius, Elizabeth; DeWitt, John; Ploutz-Snyder, Lori

    2016-01-01

    Change in maximal aerobic capacity (VO2pk) in response to exercise training and disuse is highly variable among individuals. Factors that could contribute to the observed variability (lean mass, daily activity, diet, sleep, stress) are not routinely controlled in studies. The NASA bed rest (BR) studies use a highly controlled hospital based model as an analog of spaceflight. In this study, diet, hydration, physical activity and light/dark cycles were precisely controlled and provided the opportunity to investigate individual variability. PURPOSE. Evaluate the contribution of exercise intensity and lean mass on change in VO2pk during 70-d of BR or BR + exercise. METHODS. Subjects completed 70-d of BR alone (CON, N=9) or BR + exercise (EX, N=17). The exercise prescription included 6 d/wk of aerobic exercise at 70 - 100% of max and 3 d/wk of lower body resistance exercise. Subjects were monitored 24 hr/d. VO2pk and lean mass (iDXA) were measured pre and post BR. ANOVA was used to evaluate changes in VO2pk pre to post BR. Subjects were retrospectively divided into high and low responders based on change in VO2pk (CON > 20% loss, n=5; EX >10% loss, n=4, or 5% gain, n=4) to further understand individual variability. RESULTS. VO2pk decreased from pre to post BR in CON (Pexercise intensity. CONCLUSION. Change in VO2pk in response to disuse and exercise was highly variable among individuals, even in this tightly controlled study. Loss in lean mass accounts for a significant degree of variability in the CON; however, training induced gains in VO2pk appear unrelated to lean mass or exercise intensity.

  1. Replacement of daily load attenuates but does not prevent changes to the musculoskeletal system during bed rest

    Directory of Open Access Journals (Sweden)

    Peter R. Cavanagh, PhD DSc

    2016-12-01

    Full Text Available The dose-response effects of exercise in reduced gravity on musculoskeletal health have not been well documented. It is not known whether or not individualized exercise prescriptions can be effective in preventing the substantial loss in bone mineral density and muscle function that have been observed in space flight and in bed rest. In this study, typical daily loads to the lower extremities were quantified in free-living subjects who were then randomly assigned to control or exercise groups. Subjects were confined to 6-degree head-down bed rest for 84 days. The exercise group performed individually prescribed 1 g loaded locomotor exercise to replace their free-living daily load. Eleven subjects (5 exercise, 6 control completed the protocol. Volumetric bone mineral density results from quantitative computed tomography demonstrated that control subjects lost significant amounts of bone in the intertrochanteric and total hip regions (p  0.0125. Pre-and post-bed rest muscle volumes were calculated from analysis of magnetic resonance imaging data. The exercise group retained a larger percentage of their total quadriceps and gastrocnemius muscle volume (−7.2% ± 5.9, −13.8% ± 6.1, respectively than their control counterparts (−23.3% ± 5.9, −33.0 ± 8.2, respectively; p  0.05. The decline in VO2max was 17% ± 18 in exercising subjects (p  0.05. In summary, the decline in a number of important measures of musculoskeletal and cardiovascular health was attenuated but not eliminated by a subject-specific program of locomotor exercise designed to replace daily load accumulated during free living. We conclude that single daily bouts of exposure to locomotor exercise can play a role in a countermeasures program during bed rest, and perhaps space flight, but are not sufficient in their own right to ensure musculoskeletal or cardiovascular health. Keywords: Space flight, Bed rest, Exercise, Biomechanics, Simulation, Gravity

  2. Analog Exercise Hardware to Implement a High Intensity Exercise Program During Bed Rest

    Science.gov (United States)

    Loerch, Linda; Newby, Nate; Ploutz-Snyder, Lori

    2012-01-01

    Background: In order to evaluate novel countermeasure protocols in a space flight analog prior to validation on the International Space Station (ISS), NASA's Human Research Program (HRP) is sponsoring a multi-investigator bedrest campaign that utilizes a combination of commercial and custom-made exercise training hardware to conduct daily resistive and aerobic exercise protocols. This paper will describe these pieces of hardware and how they are used to support current bedrest studies at NASA's Flight Analog Research Unit in Galveston, TX. Discussion: To implement candidate exercise countermeasure studies during extended bed rest studies the following analog hardware are being utilized: Stand alone Zero-Gravity Locomotion Simulator (sZLS) -- a custom built device by NASA, the sZLS allows bedrest subjects to remain supine as they run on a vertically-oriented treadmill (0-15 miles/hour). The treadmill includes a pneumatic subject loading device to provide variable body loading (0-100%) and a harness to keep the subject in contact with the motorized treadmill to provide a ground reaction force at their feet that is quantified by a Kistler Force Plate. Supine Cycle Ergometer -- a commercially available supine cycle ergometer (Lode, Groningen, Netherlands) is used for all cycle ergometer sessions. The ergometer has adjustable shoulder supports and handgrips to help stabilize the subject during exercise. Horizontal Squat Device (HSD) -- a custom built device by Quantum Fitness Corp (Stafford, TX), the HSD allows for squat exercises to be performed while lying in a supine position. The HSD can provide 0 to 600 pounds of force in selectable 5 lb increments, and allows hip translation in both the vertical and horizontal planes. Prone Leg Curl -- a commercially available prone leg curl machine (Cybex International Inc., Medway, MA) is used to complete leg curl exercises. Horizontal Leg Press -- a commercially available horizontal leg press (Quantum Fitness Corporation) is

  3. Once-Yearly Zoledronic Acid and Days of Disability, Bed Rest, and Back Pain: Randomized, Controlled HORIZON Pivotal Fracture Trial

    Science.gov (United States)

    Cauley, Jane A.; Black, Dennis; Boonen, Steven; Cummings, Steven R.; Mesenbrink, Peter; Palermo, Lisa; Man, Zulema; Hadji, Peyman; Reid, Ian R.

    2016-01-01

    The objective of this study was to determine the effect of once-yearly zoledronic acid on the number of days of back pain and the number of days of disability (ie, limited activity and bed rest) owing to back pain or fracture in postmenopausal women with osteoporosis. This was a multicenter, randomized, double-blind, placebo-controlled trial in 240 clinical centers in 27 countries. Participants included 7736 postmenopausal women with osteoporosis. Patients were randomized to receive either a single 15-minute intravenous infusion of zoledronic acid (5 mg) or placebo at baseline, 12 months, and 24 months. The main outcome measures were self-reported number of days with back pain and the number of days of limited activity and bed rest owing to back pain or a fracture, and this was assessed every 3 months over a 3-year period. Our results show that although the incidence of back pain was high in both randomized groups, women randomized to zoledronic acid experienced, on average, 18 fewer days of back pain compared with placebo over the course of the trial (p = .0092). The back pain among women randomized to zoledronic acid versus placebo resulted in 11 fewer days of limited activity (p = .0017). In Cox proportional-hazards models, women randomized to zoledronic acid were about 6% less likely to experience 7 or more days of back pain [relative risk (RR) = 0.94, 95% confidence interval (CI) 0.90–0.99] or limited activity owing to back pain (RR = 0.94, 95% CI 0.87–1.00). Women randomized to zoledronic acid were significantly less likely to experience 7 or more bed-rest days owing to a fracture (RR = 0.58, 95% CI 0.47–0.72) and 7 or more limited-activity days owing to a fracture (RR = 0.67, 95% CI 0.58–0.78). Reductions in back pain with zoledronic acid were independent of incident fracture. Our conclusion is that in women with postmenopausal osteoporosis, a once-yearly infusion with zoledronic acid over a 3-year period significantly reduced the number of days that

  4. Effect of β-hydroxy-β-methylbutyrate (HMB) on lean body mass during 10 days of bed rest in older adults.

    Science.gov (United States)

    Deutz, Nicolaas E P; Pereira, Suzette L; Hays, Nicholas P; Oliver, Jeffery S; Edens, Neile K; Evans, Chris M; Wolfe, Robert R

    2013-10-01

    Loss of muscle mass due to prolonged bed rest decreases functional capacity and increases hospital morbidity and mortality in older adults. To determine if HMB, a leucine metabolite, is capable of attenuating muscle decline in healthy older adults during complete bed rest. A randomized, controlled, double-blinded, parallel-group design study was carried out in 24 healthy (SPPB ≥ 9) older adult subjects (20 women, 4 men), confined to complete bed rest for ten days, followed by resistance training rehabilitation for eight weeks. Subjects in the experimental group were treated with HMB (calcium salt, 1.5 g twice daily - total 3 g/day). Control subjects were treated with an inactive placebo powder. Treatments were provided starting 5 days prior to bed rest till the end rehabilitation phase. DXA was used to measure body composition. Nineteen eligible older adults (BMI: 21-33; age: 60-76 year) were evaluable at the end of the bed rest period (Control n = 8; Ca-HMB n = 11). Bed rest caused a significant decrease in total lean body mass (LBM) (2.05 ± 0.66 kg; p = 0.02, paired t-test) in the Control group. With the exclusion of one subject, treatment with HMB prevented the decline in LBM over bed rest -0.17 ± 0.19 kg; p = 0.23, paired t-test). There was a statistically significant difference between treatment groups for change in LBM over bed rest (p = 0.02, ANOVA). Sub-analysis on female subjects (Control = 7, HMB = 8) also revealed a significant difference in change in LBM over bed rest between treatment groups (p = 0.04, ANOVA). However, differences in function parameters could not be observed, probably due to the sample size of the study. In healthy older adults, HMB supplementation preserves muscle mass during 10 days of bed rest. These results need to be confirmed in a larger trial. Copyright © 2013 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  5. Increased rate of whole body lipolysis before and after 9 days of bed rest in healthy young men born with low birth weight

    DEFF Research Database (Denmark)

    Alibegovic, Amra Ciric; Hojbjerre, Lise; Sonne, Mette

    2010-01-01

    Background: Individuals born with low birth weight (LBW) are at risk of developing type 2 diabetes mellitus (T2D), which may be precipitated by physical inactivity. Methods: 22 LBW and 23 controls were studied before and after bed rest by the hyperinsulinemic euglycemic clamp combined with indirect...... calorimetry, infusion of stable isotope tracers, preceded by an intravenous glucose tolerance test. Results: LBW subjects had similar BMI, but elevated abdominal obesity compared with controls. The basal rate of whole body lipolysis (WBL) was elevated in LBW subjects with and without correction for abdominal...... insulin resistance when exposed to bed rest in LBW subjects. Nine days of bed rest causes severe peripheral insulin resistance, reduced WBL and skeletal muscle HSL activity, as well as a compensatory increased insulin secretion, with no differences in LBW subjects and controls....

  6. Endothelial function after 10 days of bed rest in individuals at risk for type 2 diabetes and cardiovascular disease

    DEFF Research Database (Denmark)

    Sonne, Mette Paulii; Højbjerre, Lise; Alibegovic, Amra C

    2011-01-01

    Aims: Physical inactivity is considered to be deleterious to vascular health, and in particular first degree relatives to patients with type 2 diabetes (FDR) and persons born with low birth weight (LBW) who may later in life develop cardiovascular disease. A period of imposed physical inactivity...... could unmask this risk. We hypothesized that the impact of physical inactivity on endothelial function would be more marked in subjects at increased risk for type 2 diabetes and cardiovascular disease, (LBW and FDR) compared with a matched control group (CON); all recruited via advertisements and via...... the Danish Birth Registry.Methods and Results: Twenty LBW and twenty CON and thirteen FDR were studied before and after ten days of bed rest. Forearm blood flow (FBF) was measured by venous occlusion plethysmography during brachial intra-arterial infusions of acetylcholine and adenosine at baseline...

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

    Science.gov (United States)

    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 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.

  8. Hummocky moraine: sedimentary record of stagnant Laurentide Ice Sheet lobes resting on soft beds

    Science.gov (United States)

    Eyles, N.; Boyce, J. I.; Barendregt, R. W.

    1999-02-01

    Over large areas of the western interior plains of North America, hummocky moraine (HM) formed at the margins of Laurentide Ice Sheet (LIS) lobes that flowed upslope against topographic highs. Current depositional models argue that HM was deposited supraglacially from stagnant debris-rich ice (`disintegration moraine'). Across southern Alberta, Canada, map and outcrop data show that HM is composed of fine-grained till as much as 25 m thick containing rafts of soft, glaciotectonized bedrock and sediment. Chaotic, non-oriented HM commonly passes downslope into weakly-oriented hummocks (`washboard moraine') that are transitional to drumlins in topographic lows; the same subsurface stratigraphy and till facies is present throughout. These landforms, and others such as doughnut-like `rim ridges', flat-topped `moraine plateaux' and linear disintegration ridges, are identified as belonging to subglacially-deposited soft-bed terrain. This terrain is the record of ice lobes moving over deformation till derived from weakly-lithified, bentonite-rich shale. Drumlins record continued active ice flow in topographic lows during deglaciation whereas HM was produced below the outer stagnant margins of ice lobes by gravitational loading (`pressing') of remnant dead ice blocks into wet, plastic till. Intervening zones of washboard moraine mark the former boundary of active and stagnant ice and show `hybrid' drumlins whose streamlined form has been altered by subglacial pressing (` humdrums') below dead ice. The presence of hummocky moraine over a very large area of interior North America provides additional support for glaciological models of a soft-bedded Laurentide Ice Sheet.

  9. Age-related differences in lean mass, protein synthesis and skeletal muscle markers of proteolysis after bed rest and exercise rehabilitation

    DEFF Research Database (Denmark)

    Tanner, Ruth E; Brunker, Lucille B; Agergaard, Jakob

    2015-01-01

    during a constant stable isotope infusion in the postabsorptive state and after essential amino acid (EAA) ingestion on three occasions: before (PRE), after bed rest and after rehabilitation. Samples were assessed for protein synthesis, mTORC1 signalling, REDD1/2 expression and molecular markers related...... to muscle proteolysis (MURF1, MAFBX, AMPKα, LC3II/I, Beclin1). We found that leg lean mass and strength decreased in older but not younger adults after bedrest (P protein synthesis increased before bed rest in both age groups...... (P protein synthesis rates and increased MAFBX mRNA, p-AMPKα and the LC3II/I ratio (P

  10. Management of HAPE with bed rest and supplemental oxygen in hospital setting at high altitude (11,500 ft): A review of 43 cases

    OpenAIRE

    Sanjay Singhal; Srinivasa A Bhattachar; Sumit Rungta

    2017-01-01

    Objectives: To evaluate the safety and efficacy of treating high-altitude pulmonary edema (HAPE) by bed rest and supplemental oxygen in hospital setting at high altitude. Materials and Methods: In a prospective case series, all patients who were diagnosed clinically with HAPE on admission to our hospital located at a height of 11,500 ft were evaluated and managed with bed rest and oxygen supplementation. Results: A total of 43 patients of HAPE with mean age of 31 years (range 20–48 years) wer...

  11. Anabolic resistance assessed by oral stable isotope ingestion following bed rest in young and older adult volunteers: Relationships with changes in muscle mass.

    Science.gov (United States)

    Biolo, Gianni; Pišot, Rado; Mazzucco, Sara; Di Girolamo, Filippo Giorgio; Situlin, Roberta; Lazzer, Stefano; Grassi, Bruno; Reggiani, Carlo; Passaro, Angelina; Rittweger, Joern; Gasparini, Mladen; Šimunič, Boštjan; Narici, Marco

    2017-10-01

    Aging and experimental bed rest are associated with muscle atrophy and resistance to post-prandial stimulation of protein synthesis or anabolic resistance (AR). We have used in young and older adult volunteers, during short-term bed rest, a quick and non-invasive method, based on a single oral bolus of the stable isotope L[ring- 2 H 5 ]phenylalanine (D 5 Phe), to determine post-prandial AR, defined as ratio between irreversible hydroxylation and incorporation into body protein of ingested phenylalanine. We compared in older (O, 59 ± 1 y) and young (Y, 23 ± 1 y) healthy male volunteers the effects of two-week bed rest on post-prandial protein kinetics, assessed during absorption of a standard ready-to-use oral nutritional supplement, through stable-labeled isotope amino acid D 5 Phe, diluted in water, given as single oral load. The metabolic fate of D 5 Phe is either utilization for protein synthesis or irreversible hydroxylation to L[ring- 2 H 4 ]tyrosine (D 4 Tyr). AR was defined as ratio between the areas under the curves of D 4 Tyr-to-D 5 Phe plasma concentrations over 6 h meal absorption. To determine the relationships between AR and muscle changes following bed rest, quadriceps muscle volume (QMV) was determined by magnetic resonance imaging (MRI). At baseline, in pooled Y and O subjects, values of AR were inversely correlated with QMV (R = -0.75; p < 0.03). Following 2-weeks of inactivity, there were significant bed rest effects on AR (p < 0.01) and QMV (p < 0.03), as well as significant bed rest × group interaction for AR (p < 0.03; +9.2% in Y; +21.9% in O) and QMV (p < 0.05; -5.7% in Y; -%7.3 in O). In pooled subjects, the percentage delta changes in AR and QMV, induced by bed rest, were inversely correlated (R = -0.57; p < 0.05). Bed rest-induced AR is much greater in the older than in younger adults. We have developed a new, simple, non-invasive method for the assessment of AR. The results indicate that this metabolic

  12. Impact of 9 days of bed rest on hepatic and peripheral insulin action, insulin secretion, and whole-body lipolysis in healthy young male offspring of patients with type 2 diabetes

    DEFF Research Database (Denmark)

    Alibegovic, Amra C; Højbjerre, Lise; Sonne, Mette P

    2009-01-01

    decrease in whole-body insulin sensitivity in both groups. Hepatic insulin resistance was elevated in FDR subjects prior to bed rest and was significantly augmented by bed rest in FDR (P ... deteriorates with 9 days of bed rest, converging toward similar degrees of whole-body insulin resistance. FDR subjects exhibit hepatic insulin resistance (HIR), which, in contrast to CON subjects, deteriorates in response to physical inactivity. FDR subjects exhibit reduced insulin secretion when seen...... subjects, with no significant differences between the groups. Insulin resistance induced by bed rest was fully accounted for by the impairment of nonoxidative glucose metabolism in both groups (overall P resistant FDR and healthy CON subjects...

  13. Effects of normobaric hypoxic bed rest on the thermal comfort zone.

    Science.gov (United States)

    Ciuha, Ursa; Eiken, Ola; Mekjavic, Igor B

    2015-01-01

    Future Lunar and Mars habitats will maintain a hypobaric hypoxic environment to minimise the risk of decompression sickness during the preparation for extra-vehicular activity. This study was part of a larger study investigating the separate and combined effects of inactivity associated with reduced gravity and hypoxia, on the cardiovascular, musculoskeletal, neurohumoural, and thermoregulatory systems. Eleven healthy normothermic young male subjects participated in three trials conducted on separate occasions: (1) Normobaric hypoxic ambulatory confinement, (2) Normobaric hypoxic bedrest and (3) Normobaric normoxic bedrest. Normobaric hypoxia was achieved by reduction of the oxygen fraction in the air (FiO2 = 0.141 ± 0.004) within the facility, while the effects of reduced gravity were simulated by confining the subjects to a horizontal position in bed, with all daily routines performed in this position for 21 days. The present study investigated the effect of the interventions on behavioural temperature regulation. The characteristics of the thermal comfort zone (TCZ) were assessed by a water-perfused suit, with the subjects instructed to regulate the sinusoidally varying temperature of the suit within a range considered as thermally comfortable. Measurements were performed 5 days prior to the intervention (D-5), and on days 10 (D10) and 20 (D20) of the intervention. no statistically significant differences were found in any of the characteristics of the TCZ between the interventions (HAMB, HBR and NBR), or between different measurement days (D-5, D10, D20) within each intervention. rectal temperature remained stable, whereas skin temperature (Tsk) increased during all interventions throughout the one hour trial. no difference in Tsk between D-5, D10 and D20, and between HAMB, HBR and NBR were revealed. subjects perceived the regulated temperature as thermally comfortable, and neutral or warm. we conclude that regulation of thermal comfort is not compromised by

  14. Using Natural Stable Calcium Isotopes to Rapidly Assess Changes in Bone Mineral Balance Using a Bed Rest Model to Induce Bone Loss

    Science.gov (United States)

    Morgan, J. L. L.; Skulan, J. L.; Gordon, G. E.; Smith, Scott M.; Romaniello, S. J.; Anbar, A. D.

    2012-01-01

    Metabolic bone diseases like osteoporosis result from the disruption of normal bone mineral balance (BMB) resulting in bone loss. During spaceflight astronauts lose substantial bone. Bed rest provides an analog to simulate some of the effects of spaceflight; including bone and calcium loss and provides the opportunity to evaluate new methods to monitor BMB in healthy individuals undergoing environmentally induced-bone loss. Previous research showed that natural variations in the Ca isotope ratio occur because bone formation depletes soft tissue of light Ca isotopes while bone resorption releases that isotopically light Ca back into soft tissue (Skulan et al, 2007). Using a bed rest model, we demonstrate that the Ca isotope ratio of urine shifts in a direction consistent with bone loss after just 7 days of bed rest, long before detectable changes in bone mineral density (BMD) occur. The Ca isotope variations tracks changes observed in urinary N-teleopeptide, a bone resorption biomarker. Bone specific alkaline phosphatase, a bone formation biomarker, is unchanged. The established relationship between Ca isotopes and BMB can be used to quantitatively translate the changes in the Ca isotope ratio to changes in BMD using a simple mathematical model. This model predicts that subjects lost 0.25 0.07% ( SD) of their bone mass from day 7 to day 30 of bed rest. Given the rapid signal observed using Ca isotope measurements and the potential to quantitatively assess bone loss; this technique is well suited to study the short-term dynamics of bone metabolism.

  15. PlanHab study: assessment of psycho-neuroendocrine function in male subjects during 21 d of normobaric hypoxia and bed rest.

    Science.gov (United States)

    Strewe, C; Zeller, R; Feuerecker, M; Hoerl, M; Kumprej, I; Crispin, A; Johannes, B; Debevec, T; Mekjavic, I; Schelling, G; Choukèr, A

    2017-03-01

    Immobilization and hypoxemia are conditions often seen in patients suffering from severe heart insufficiency or primary pulmonary diseases (e.g. fibrosis, emphysema). In future planned long-duration and exploration class space missions (including habitats on the moon and Mars), healthy individuals will encounter such a combination of reduced physical activity and oxygen tension by way of technical reasons and the reduced gravitational forces. These overall unconventional extraterrestrial conditions can result in yet unknown consequences for the regulation of stress-permissive, psycho-neuroendocrine responses, which warrant appropriate measures in order to mitigate foreseeable risks. The Planetary Habitat Simulation Study (PlanHab) investigated these two space-related conditions: bed rest as model of reduced gravity and normobaric hypoxia, with the aim of examining their influence on psycho-neuroendocrine responses. We hypothesized that both conditions independently increase measures of psychological stress and enhance neuroendocrine markers of stress, and that these effects would be exacerbated by combined treatment. The cross-over study composed of three interventions (NBR, normobaric normoxic horizontal bed rest; HBR, normobaric hypoxic horizontal bed rest; HAMB, normobaric hypoxic ambulatory confinement) with 14 male subjects during three sequential campaigns separated by 4 months. The psychological state was determined through three questionnaires and principal neuroendocrine responses were evaluated by measuring cortisol in saliva, catecholamine in urine, and endocannabinoids in blood. The results revealed no effects after 3 weeks of normobaric hypoxia on psycho-neuroendocrine responses. Conversely, bed rest induced neuroendocrine alterations that were not influenced by hypoxia.

  16. Effect of enforced physical inactivity induced by 60-day of bed rest on hepatic markers of NAFLD in healthy normal-weight women.

    Science.gov (United States)

    Rudwill, Floriane; Bergouignan, Audrey; Gastebois, Caroline; Gauquelin-Koch, Guillemette; Lefai, Etienne; Blanc, Stéphane; Simon, Chantal

    2015-06-01

    Physical inactivity leads to a cluster of metabolic disorders that have been associated with non-alcoholic fatty liver diseases. We tested whether physical inactivity increases hepatic biomarkers of NAFLDs. Sixteen normal-weight healthy women (body mass index = 21.2 ± 0.5 kg/m(2) ) were studied under controlled energy balance conditions during a previous 60-day bed rest with (n = 8) or without (n = 8) a combined aerobic/resistive exercise protocol. Stored samples were retrospectively used to measure plasma hepatic markers, i.e. steatosis-related alanine and aspartate transaminases, cytokeratin 18 and angiopoietin-like 3, at baseline, after 30 and 60 days of bed rest. Fasting insulin and triglycerides were measured at baseline and after 30 days of bed rest. Two indexes were calculated, one combining alanine and aspartate transaminase and cytokeratin 18 and another cytokeratin 18, homeostasis model assessment of insulin resistance and aspartate aminotransferase. Sixty days of bed rest increased all hepatic markers (P inactive conditions. Physical inactivity increases, independent of fat mass, hepatic markers of steatosis and steatohepatitis. Regular exercise can limit these physical inactivity-induced metabolic alterations. Future studies need to elucidate the underlying mechanisms. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. Management of HAPE with bed rest and supplemental oxygen in hospital setting at high altitude (11,500 ft: A review of 43 cases

    Directory of Open Access Journals (Sweden)

    Sanjay Singhal

    2017-01-01

    Full Text Available Objectives: To evaluate the safety and efficacy of treating high-altitude pulmonary edema (HAPE by bed rest and supplemental oxygen in hospital setting at high altitude. Materials and Methods: In a prospective case series, all patients who were diagnosed clinically with HAPE on admission to our hospital located at a height of 11,500 ft were evaluated and managed with bed rest and oxygen supplementation. Results: A total of 43 patients of HAPE with mean age of 31 years (range 20–48 years were admitted to our hospital. Infections followed by unaccustomed physical exertion were the predominant risk factors. 95.35% of the patients improved successfully with oxygen and bed rest alone with mean hospital stay of 2.67 ± 1.06 (1–6 days. Two patients (4.65% required nifedipine and evacuation to lower altitude. Of this, one patient suffering from concomitant viral infection expired 4 days after evacuation to near sea level. Conclusion: Majority of the patients with HAPE where medical facilities are available can be safely treated with bed rest and oxygen supplementation at moderate high altitude without descent.

  18. The effect of alternate-day caloric restriction on the metabolic consequences of 8 days of bed rest in healthy lean men

    DEFF Research Database (Denmark)

    Harder-Lauridsen, Nina Majlund; Nielsen, Signe Tellerup; Mann, Sebastian Porsdam

    2017-01-01

    (control group, n = 10); and 2) 8 days of bed rest with 25% of total energy requirements every other day and 175% of total energy requirements every other day (ADCR group). Oral glucose tolerance testing, dual-energy X-ray absorptiometry (DXA) scans, magnetic resonance imaging of the abdomen and brain, V̇o......Physical activity and alternate-day fasting/caloric restriction may both ameliorate aspects of the metabolic syndrome, such as insulin resistance, visceral fat mass accumulation, and cognitive impairment by overlapping mechanisms. The purpose of this study was to test the hypothesis that alternate-day...... caloric restriction (ADCR) with overall energy balance would reduce insulin resistance and accumulation of visceral fat, in addition to improving cognitive functions, after 8 consecutive days in bed. Healthy, lean men (n = 20) were randomized to 1) 8 days of bed rest with three daily isoenergetic meals...

  19. Effect of 21-day head down bed rest on urine proteins related to endothelium: Correlations with changes in carbohydrate metabolism

    Science.gov (United States)

    Kashirina, D.; Pastushkova, L.; Custaud, M. A.; Dobrokhotov, I.; Brzhozovsky, A.; Navasiolava, N.; Nosovsky, A.; Kononikhin, A.; Nikolaev, E.; Larina, I.

    2017-08-01

    We performed liquid chromatography-mass spectrometric study of the urine proteome in 8 healthy volunteers aged between 20 and 44 y.o. who have completed 21-day head-down bed rest. ANDSystem software which builds associative networks was used to identify the urinary proteins functionally related to the endothelium. We identified 7 endothelium-related biological processes, directly linked to 13 urine proteins. We performed manual annotation of the proteins which were the most important in terms of endothelial functions. Analysis of the correlations with biochemical variables revealed a positive correlation between fasting blood glucose and the following urine proteins: albumin, CD44 antigen, endothelial protein C receptor, mucin-1, osteopontin, receptor tyrosine kinase. As well, we found a positive correlation between HOMA-insulin resistance index and the following urine proteins: endothelial protein C receptor and syndecan-4. These results might suggest the involvement of above-mentioned proteins in glucose metabolism and their participation in the response to changes in blood glucose level.

  20. [Remodeling simulation of human femur under bed rest and spaceflight circumstances based on three dimensional finite element analysis].

    Science.gov (United States)

    Yang, Wenting; Wang, Dongmei; Lei, Zhoujixin; Wang, Chunhui; Chen, Shanguang

    2017-12-01

    Astronauts who are exposed to weightless environment in long-term spaceflight might encounter bone density and mass loss for the mechanical stimulus is smaller than normal value. This study built a three dimensional model of human femur to simulate the remodeling process of human femur during bed rest experiment based on finite element analysis (FEA). The remodeling parameters of this finite element model was validated after comparing experimental and numerical results. Then, the remodeling process of human femur in weightless environment was simulated, and the remodeling function of time was derived. The loading magnitude and loading cycle on human femur during weightless environment were increased to simulate the exercise against bone loss. Simulation results showed that increasing loading magnitude is more effective in diminishing bone loss than increasing loading cycles, which demonstrated that exercise of certain intensity could help resist bone loss during long-term spaceflight. At the end, this study simulated the bone recovery process after spaceflight. It was found that the bone absorption rate is larger than bone formation rate. We advise that astronauts should take exercise during spaceflight to resist bone loss.

  1. Bed rest during pregnancy

    Science.gov (United States)

    ... ER. Multiple gestations. In: Gabbe SG, Niebyl JR, Simpson JL, et al, eds. Obstetrics: Normal and Problem ... labor and birth. In: Gabbe SG, Niebyl JR, Simpson JL, et al, eds. Obstetrics: Normal and Problem ...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  5. Collagen content in the vastus lateralis and the soleus muscle following a 90-day bed rest period with or without resistance exercises

    DEFF Research Database (Denmark)

    Nielsen, Rasmus Oestergaard; Schjerling, Peter; Tesch, Per

    2015-01-01

    training serves as a proxy for the conditions in space. Therefore, ground-based studies may improve the understanding of the consequences of long-term inactivity. PURPOSE: the purpose is to compare the change in collagen protein in the vastus lateralis (VL) and the soleus (SOL) muscle amongst persons......INTRODUCTION: spaceflight seems associated with deterioration of the function of the skeletal muscles. Since muscle collagen is critical for muscle function, an improved understanding of the content of the muscle collagen during long-term inactivity seems important. Bed-rest with in-bed resistance...... collagen/mg protein [95% CI: -25.6; 12.6], p=0.50). There was no difference in the effect of BR versus BRE over time (mean difference -2.78 μg collagen/mg protein [95% CI: -29.7; 24.1], p=0.82). CONCLUSION: muscle collagen content in the VL or SOL muscle does not seem to differ after a 90-day bed rest...

  6. How does lateral tilting affect the internal strains in the sacral region of bed ridden patients? : a contribution to pressure ulcer prevention

    NARCIS (Netherlands)

    Oomens, C.W.J.; Broek, M.; Hemmes, B.; Bader, D.L.

    2016-01-01

    Background Repositioning of individuals with reduced mobility and at risk of pressure ulcers is an essential preventive step. Manual or automatic lateral tilting is a way of doing this and the international guidelines propose a 30° to 40°side lying position. The goal of the present study was to

  7. Reducing bed rest time from five to three hours does not increase complications after cardiac catheterization: the THREE CATH Trial 1

    Science.gov (United States)

    Matte, Roselene; Hilário, Thamires de Souza; Reich, Rejane; Aliti, Graziella Badin; Rabelo-Silva, Eneida Rejane

    2016-01-01

    Abstract Objective: to compare the incidence of vascular complications in patients undergoing transfemoral cardiac catheterization with a 6F introducer sheath followed by 3-hour versus 5-hour rest. Methods: randomized clinical trial. Subjects in the intervention group (IG) ambulated 3 hours after sheath removal, versus 5 hours in the control group (CG). All patients remained in the catheterization laboratory for 5 hours and were assessed hourly, and were contacted 24, 48, and 72 h after hospital discharge. Results: the sample comprised 367 patients in the IG and 363 in the GC. During cath lab stay, hematoma was the most common complication in both groups, occurring in 12 (3%) IG and 13 (4%) CG subjects (P=0.87). Bleeding occurred in 4 (1%) IG and 6 (2%) CG subjects (P=0.51), and vasovagal reaction in 5 (1.4%) IG and 4 (1.1%) CG subjects (P=0.75). At 24-h, 48-h, and 72-h bruising was the most commonly reported complication in both groups. None of the comparisons revealed any significant between-group differences. Conclusion: the results of this trial show that reducing bed rest time to 3 hours after elective cardiac catheterization is safe and does not increase complications as compared with a 5-hour rest. ClinicalTrials.gov Identifier: NCT-01740856 PMID:27463113

  8. The T-allele of TCF7L2 rs7903146 associates with a reduced compensation of insulin secretion for insulin resistance induced by 9 days of bed rest

    DEFF Research Database (Denmark)

    Alibegovic, Amra C; Sonne, Mette P; Højbjerre, Lise

    2010-01-01

    of FPIR in response to insulin resistance induced by bed rest was lower in carriers of the T-allele (P hepatic insulin resistance......OBJECTIVE: The aim of this study was to determine whether the type 2 diabetes-associated T-allele of transcription factor 7-like 2 (TCF7L2) rs7903146 associates with impaired insulin secretion to compensate for insulin resistance induced by bed rest. RESEARCH DESIGN AND METHODS: A total of 38....... The genetic analyses were done assuming a dominant model of inheritance. RESULTS: The first-phase insulin response (FPIR) was significantly lower in carriers of the T-allele compared with carriers of the CC genotype before bed rest, with and without correction for insulin resistance. The incremental rise...

  9. Effect of 5 weeks horizontal bed rest on human muscle thickness and architecture of weight bearing and non-weight bearing muscles.

    Science.gov (United States)

    de Boer, Maarten D; Seynnes, Olivier R; di Prampero, Pietro E; Pisot, Rado; Mekjavić, Igor B; Biolo, Gianni; Narici, Marco V

    2008-09-01

    The aim of the present study was to investigate the changes in thickness, fascicle length (L (f)) and pennation angle (theta) of the antigravity gastrocnemius medialis (GM) and vastus lateralis (VL) muscles, and the non-antigravity tibialis anterior (TA) and biceps brachii (BB) muscles measured by ultrasonography in ten healthy males (aged 22.3 +/- 2.2 years) in response to 5 weeks of horizontal bed rest (BR). After BR, muscle thickness decreased by 12.2 +/- 8.8% (P antigravity muscles of the lower limbs, the GM deteriorated to a greater extent than the VL is possibly related to the differences in relative load that this muscle normally experiences during daily loading. The dissimilar response in antigravity and non-antigravity muscles to unloading likely reflects differences in loading under normal conditions. The significant structural alterations of the GM and VL muscles highlight the rapid remodelling of muscle architecture occurring with disuse.

  10. Effects of β-hydroxy-β-methylbutyrate on skeletal muscle mitochondrial content and dynamics, and lipids after 10 days of bed rest in older adults.

    Science.gov (United States)

    Standley, Robert A; Distefano, Giovanna; Pereira, Suzette L; Tian, Min; Kelly, Owen J; Coen, Paul M; Deutz, Nicolaas E P; Wolfe, Robert R; Goodpaster, Bret H

    2017-11-01

    Loss of muscle mass during periods of disuse likely has negative health consequences for older adults. We have previously shown that β-hydroxy-β-methylbutyrate (HMB) supplementation during 10 days of strict bed rest (BR) attenuates the loss of lean mass in older adults. To elucidate potential molecular mechanisms of HMB effects on muscle during BR and resistance training rehabilitation (RT), we examined mediators of skeletal muscle mitochondrial dynamics, autophagy and atrophy, and intramyocellular lipids. Nineteen older adults (60-76 yr) completed 10 days BR followed by 8-wk RT rehabilitation. Subjects were randomized to either HMB (3 g/day HMB; n = 11) or control (CON; n = 8) groups. Skeletal muscle cross-sectional area (CSA) was determined by histology from percutaneous vastus lateralis biopsies. We measured protein markers of mitochondrial content [oxidative phosphorylation (OXPHOS)], fusion and fission (MFN2, OPA1, FIS1, and DRP1), autophagy (Beclin1, LC3B, and BNIP3), and atrophy [poly-ubiquinated proteins (poly-ub)] by Western blot. Fatty acid composition of several lipid classes in skeletal muscle was measured by infusion-MS analysis. Poly-ub proteins and OXPHOS complex I increased in both groups following BR ( P HMB group ( P = 0.055). RT rehabilitation increased OXPHOS complex II protein ( P HMB group. In addition, higher levels of DRP1 and MFN2 were maintained in the HMB group after RT ( P HMB influences mitochondrial dynamics and lipid metabolism during disuse atrophy and rehabilitation. NEW & NOTEWORTHY Mitochondrial content and dynamics remained unchanged over 10 days of BR in older adults. HMB stimulated intramuscular lipid storage as triacylglycerol following 10 days of bed rest (BR) and maintained higher mitochondrial OXPHOS content and dynamics during the 8-wk resistance exercise rehabilitation program. Copyright © 2017 the American Physiological Society.

  11. 21 Days head-down bed rest induces weakening of cell-mediated immunity - Some spaceflight findings confirmed in a ground-based analog.

    Science.gov (United States)

    Kelsen, Jens; Bartels, Lars Erik; Dige, Anders; Hvas, Christian Lodberg; Frings-Meuthen, Petra; Boehme, Gisela; Thomsen, Marianne Kragh; Fenger-Grøn, Morten; Dahlerup, Jens Frederik

    2012-08-01

    Several studies indicate a weakening of cell-mediated immunity (CMI) and reactivation of latent herpes viruses during spaceflight. We tested the hypothesis that head-down bed rest (HDBR), a ground-based analog of spaceflight, mimics the impact of microgravity on human immunity. Seven healthy young males underwent two periods of 3 weeks HDBR in the test facility of the German Aerospace Center. As a nutritional countermeasure aimed against bone demineralisation, 90 mmol potassium bicarbonate (KHCO(3)) was administered daily in a crossover design. Blood samples were drawn on five occasions. Whole blood was stimulated with antigen i.e. Candida albicans, purified protein derivative (PPD) tuberculin, tetanus toxoid and Cytomegalovirus (CMV) (CMV-QuantiFERON). Flow cytometric analysis included CD4(+)CD25(+)CD127(-)FOXP3(+) regulatory T cells (Tregs), γδ T cells, B cells, NK cells and dendritic cells. In one of the two bed rest periods, we observed a significant decrease in production of interleukin-2 (IL-2), interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) following phytohemagglutinin (PHA) stimulation, with a rapid normalization being observed after HDBR. The cytokine levels showed a V-shaped pattern that led to a relativeTh2-shift in cytokine balance. Only three individuals responded to the specific T cell antigens without showing signs of an altered response during HDBR, nor did we observe reactivation of CMV or Epstein-Barr virus (EBV). Of unknown significance, dietary supplementation with KHCO(3) counteracted the decrease in IL-2 levels during HDBR, while there was no impact on other immunological parameters. We conclude that discrete alterations in CMI may be induced by HDBR in selected individuals. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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

  13. Effect of computerized cognitive training with virtual spatial navigation task during bed rest immobilization and recovery on vascular function: A pilot study

    Directory of Open Access Journals (Sweden)

    Goswami N

    2015-02-01

    Full Text Available Nandu Goswami,1 Voyko Kavcic,2 Uros Marusic,3 Bostjan Simunic,3 Andreas Rössler,1 Helmut Hinghofer-Szalkay,1 Rado Pisot3 1Institute of Physiology, Medical University of Graz, Graz, Austria; 2Institute of Gerontology, Wayne State University, Detroit, MI, USA; 3Institute for Kinesiology Research, University of Primorska, Ankaran, Slovenia Abstract: We investigated the effects of bed rest (BR immobilization, with and without computerized cognitive training with virtual spatial navigation task (CCT, on vascular endothelium on older subjects. The effects of 14-day BR immobilization in healthy older males (n=16 of ages 53–65 years on endothelial function were studied using EndoPAT®, a noninvasive and user-independent method. From the group of 16 older men, 8 randomly received CCT during the BR, using virtual navigation tasks in a virtual environment with joystick device. In all the cases, EndoPAT assessments were done at pre- and post-BR immobilization as well as following 28 days of ambulatory recovery. The EndoPAT index increased from 1.53±0.09 (mean ± standard error of the mean at baseline to 1.61±0.16 following immobilization (P=0.62 in the group with CCT. The EndoPAT index decreased from 2.06±0.13 (mean ± standard error of the mean at baseline to 1.70±0.09 at the last day of BR study, day 14 (BR14 (P=0.09 in the control group. Additionally, there were no statistically significant differences between BR14 and at 28 days of follow-up (rehabilitation program (R28. Our results show a trend of immobilization in older persons affecting the vasoconstrictory endothelial response. As the control subjects had a greater increase in EndoPAT index after R28 (+0.018 compared to subjects who had cognitive training (+0.11 (calculated from the first day of BR study, it is possible that cognitive training during BR does not improve endothelial function but rather contributes to slowing down the impairment of endothelial function. Finally, our results

  14. Calf tissue liquid stowage and muscular and deep vein distension in orthostatic tests after a 90-day head down bed rest

    Science.gov (United States)

    Arbeille, P.A.; Kerbeci, P.; Audebert, P.; Capri, A.; Pascaud, L.

    2005-08-01

    The objectives were to assess the contribution of (1) the calf veins distension and(2) the tissue liquid stowage during standtest, to orthostatic intolerance "OI" after a head down bed rest (HDBR) of 90days. Method: The population consisted of a control group (Co-gr, n=9) and an exercise Fly wheel counter-measure group (CM-gr, n=9). Calf vein cross sectional area (CSA) and surrounding tissue liquid content (tissue image darkness) were assessed by echography during pre and post HDBR stand-tests. Results: From supine to standing (post HDBR), the Tibial and muscular vein CSA increased significantly in non tolerant subjects whereas in tolerant subjects the vein CSA did not change. Post HDBR the tissue image darkness (proportional to tissue liquid content) increased more from supine to standing in non tolerant than in tolerant subjects. No significant difference were found between Co and exercise CM groups. Conclusion: High calf vein CSA and tissue liquid content increase at post-HDBR stand-test were significantly correlated with occurrence of OI but not with CM.

  15. Effect of 3-Day Bed Rest on the Basal Sympathetic Activity and Responsiveness of this System to Physiological Stimuli In Athletes and Sedentary Subjects

    Science.gov (United States)

    Smorawinski, Jerzy; Adrian, Jacek; Kaciuba-Uscilko, Hanna; Nazar, Krystyna; Greenleaf, John E.; Dalton, P. Bonnie (Technical Monitor)

    2002-01-01

    The aims of this study were: (1) to examine the effect of three days of bed rest (BR) on basal plasma epinephrine [E] and norepinephrine [NE] and the catecholamine responses to various physiological stimuli, and (2) to find out whether previous physical activity modifies effects of BR. In the first series, 29 young men (11 sedentary students, 8 endurance and 10 strength trained athletes) were submitted to oral glucose tolerance test in supine position and to active orthostatic test before and after 3 days of BR. Plasma [E] and [NE] were measured after overnight fast (basal condition), at 60, 120 and 180 min after glucose ingestion (70 a), and at the 8th min of unsupported standing. In the second series, other 22 subjects (12 sedentary students, 10 endurance and 10 strength trained athletes) were submitted to 2 min cold pressor test (CPT) and exercise. Plasma E and NE were determined in the supine position after overnight fast and at 60th and 120th s of hand cooling. Then, after breakfast followed by 2-3 hour sitting, the subjects performed cycle ergometer exercise with workload increasing until volitional exhaustion. Plasma [E] and [NE] were determined at the end of each load. Plasma catecholamines were determined made radioenzymatically. After BR, basal plasma [NE] was decreased in endurance and strength athletes (psedentary subjects. In neither group BR affected the basal [E]. Responses of both catecholamines to glucose load were diminished after BR in all three groups (pwork intensity after than before BR (p<0.05).

  16. Evaluation of T-wave alternans activity under stress conditions after 5 d and 21 d of sedentary head-down bed rest

    International Nuclear Information System (INIS)

    Martín-Yebra, A; Caiani, E G; Pellegrini, A; Monasterio, V; Laguna, P; Martínez, J P

    2015-01-01

    It is well known that prolonged microgravity leads to cardiovascular deconditioning, inducing significant changes in autonomic control of the cardiovascular system. This may adversely influence cardiac repolarization, and provoke cardiac rhythm disturbances. T-wave alternans (TWA), reflecting temporal and spatial repolarization heterogeneity, could be affected. The aim of this work was to test the hypothesis that 5 d and 21 d head-down (−6°) bed rest (HDBR) increases TWA, thus suggesting a higher underlying electrical instability and related arrhythmogenic risk.Forty-four healthy male volunteers were enrolled in the experiments as part of the European Space Agency’s HDBR studies. High-fidelity ECG was recorded during orthostatic tolerance (OT) and aerobic power (AP) tests, before (PRE) and after HDBR (POST). A multilead scheme for TWA amplitude estimation was used, where non-normalized and T-wave amplitude normalized TWA indices were computed. In addition, spectral analysis of heart rate variability during OT was assessed.Both 5 d and 21 d HDBR induced a reduction in orthostatic tolerance time (OTT), as well as a decrease in maximal oxygen uptake and reserve capacity, thus suggesting cardiovascular deconditioning. However, TWA indices were found not to increase. Interestingly, subjects with lower OTT after 5 d HDBR also showed higher TWA during recovery after OT testing, associated with unbalanced sympathovagal response, even before the HDBR. In contrast with previous observations, augmented ventricular heterogeneity related to 5 d and 21 d HDBR was not sufficient to increase TWA under stress conditions. (paper)

  17. Resting-state functional connectivity of the bed nucleus of the stria terminalis in post-traumatic stress disorder and its dissociative subtype.

    Science.gov (United States)

    Rabellino, Daniela; Densmore, Maria; Harricharan, Sherain; Jean, Théberge; McKinnon, Margaret C; Lanius, Ruth A

    2018-03-01

    The bed nucleus of the stria terminals (BNST) is a subcortical structure involved in anticipatory and sustained reactivity to threat and is thus essential to the understanding of anxiety and stress responses. Although chronic stress and anxiety represent a hallmark of post-traumatic stress disorder (PTSD), to date, few studies have examined the functional connectivity of the BNST in PTSD. Here, we used resting state functional Magnetic Resonance Imaging (fMRI) to investigate the functional connectivity of the BNST in PTSD (n = 70), its dissociative subtype (PTSD + DS) (n = 41), and healthy controls (n = 50). In comparison to controls, PTSD showed increased functional connectivity of the BNST with regions of the reward system (ventral and dorsal striatum), possibly underlying stress-induced reward-seeking behaviors in PTSD. By contrast, comparing PTSD + DS to controls, we observed increased functional connectivity of the BNST with the claustrum, a brain region implicated in consciousness and a primary site of kappa-opioid receptors, which are critical to the dynorphin-mediated dysphoric stress response. Moreover, PTSD + DS showed increased functional connectivity of the BNST with brain regions involved in attention and salience detection (anterior insula and caudate nucleus) as compared to PTSD and controls. Finally, BNST functional connectivity positively correlated with default-mode network regions as a function of state identity dissociation, suggesting a role of BNST networks in the disruption of self-relevant processing characterizing the dissociative subtype. These findings represent an important first step in elucidating the role of the BNST in aberrant functional networks underlying PTSD and its dissociative subtype. © 2017 Wiley Periodicals, Inc.

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

    Science.gov (United States)

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

    2008-01-01

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

  19. Intravenous saline administration in patients with severe acquired brain injury and orthostatic intolerance for tilt-table mobilization

    DEFF Research Database (Denmark)

    Riberholt, Christian; Olesen, Niels; Hovind, Peter

    2018-01-01

    Primary objective: This study aimed to investigate the effect of intravenous saline administration on orthostatic hypotension (OH) during head up tilt (HUT) and the change in the renin–angiotensin–aldosterone system before and after HUT in patients with severe acquired brain injury (ABI). Research...... artery blood flow velocity. Blood samples were collected before and after two HUT sessions separated by 1 hour and saline was administered in between. Main outcomes and results: Patients’ ability to stand upright did not change after saline administration due to OH. The patients showed signs of reduced...... fluid administration. Research focusing on the ability to retain fluid after bed rest is warranted....

  20. Experimental findings on thermal use of residues and biofuels in circulating fluidized bed combustion systems; Experimentelle Ergebnisse zur thermischen Nutzung von Rest- und Biobrennstoffen in zirkulierenden Wirbelschichtfeuerungen

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, W.; Brunne, T.; Girndt, H. [Technische Univ. Dresden (Germany); Albrecht, J. [Lurgi Lentjes Babcock, Frankfurt am Main (Germany); Youssef, M. [Minia Univ. (Egypt)

    1996-12-31

    The energy Engineering Institute of Dresden Technical University investigated the combustion and emission characteristics of a number of combustion systems, including a circulating fluidized bed system with a capacity of 0.3 MW{sub th}. Egypt`s sugar cane industry produces large volumes of bagasse. The conbustion and emission characteristics of this biofuel in a circulating fludized bed combustion systems were investigated in a joint research project of the University of Minia and Dresden Technical University. (orig.) [Deutsch] Am Institut fuer Energietechnik der TU Dresden wird das Verbrennungs- und Emissionsverhalten verschiedenster Brennstoffe in unterschiedlichen Feuerungssystemen untersucht. Neben anderen Pilotanlagen steht eine zirkulierende Wirbelschichtfeuerung (ZWFS) mit einer Leistung von 0.3 MW{sub th} zur Verfuegung. In der Zuckerrohrindustrie Aegyptens fallen grosse Mengen von Bagasse an. In einer gemeinsamen Forschungsarbeit zwischen der Universitaet Minia und der TU Dresden sollte das Verbrennungs- und Emissionsverhalten dieses Biobrennstoffes in einer ZWSF untersucht werden. (orig)

  1. Experimental findings on thermal use of residues and biofuels in circulating fluidized bed combustion systems; Experimentelle Ergebnisse zur thermischen Nutzung von Rest- und Biobrennstoffen in zirkulierenden Wirbelschichtfeuerungen

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, W; Brunne, T; Girndt, H [Technische Univ. Dresden (Germany); Albrecht, J [Lurgi Lentjes Babcock, Frankfurt am Main (Germany); Youssef, M [Minia Univ. (Egypt)

    1997-12-31

    The energy Engineering Institute of Dresden Technical University investigated the combustion and emission characteristics of a number of combustion systems, including a circulating fluidized bed system with a capacity of 0.3 MW{sub th}. Egypt`s sugar cane industry produces large volumes of bagasse. The conbustion and emission characteristics of this biofuel in a circulating fludized bed combustion systems were investigated in a joint research project of the University of Minia and Dresden Technical University. (orig.) [Deutsch] Am Institut fuer Energietechnik der TU Dresden wird das Verbrennungs- und Emissionsverhalten verschiedenster Brennstoffe in unterschiedlichen Feuerungssystemen untersucht. Neben anderen Pilotanlagen steht eine zirkulierende Wirbelschichtfeuerung (ZWFS) mit einer Leistung von 0.3 MW{sub th} zur Verfuegung. In der Zuckerrohrindustrie Aegyptens fallen grosse Mengen von Bagasse an. In einer gemeinsamen Forschungsarbeit zwischen der Universitaet Minia und der TU Dresden sollte das Verbrennungs- und Emissionsverhalten dieses Biobrennstoffes in einer ZWSF untersucht werden. (orig)

  2. Explaining variation in adult Anopheles indoor resting abundance: the relative effects of larval habitat proximity and insecticide-treated bed net use.

    Science.gov (United States)

    McCann, Robert S; Messina, Joseph P; MacFarlane, David W; Bayoh, M Nabie; Gimnig, John E; Giorgi, Emanuele; Walker, Edward D

    2017-07-17

    Spatial determinants of malaria risk within communities are associated with heterogeneity of exposure to vector mosquitoes. The abundance of adult malaria vectors inside people's houses, where most transmission takes place, should be associated with several factors: proximity of houses to larval habitats, structural characteristics of houses, indoor use of vector control tools containing insecticides, and human behavioural and environmental factors in and near houses. While most previous studies have assessed the association of larval habitat proximity in landscapes with relatively low densities of larval habitats, in this study these relationships were analysed in a region of rural, lowland western Kenya with high larval habitat density. 525 houses were sampled for indoor-resting mosquitoes across an 8 by 8 km study area using the pyrethrum spray catch method. A predictive model of larval habitat location in this landscape, previously verified, provided derivations of indices of larval habitat proximity to houses. Using geostatistical regression models, the association of larval habitat proximity, long-lasting insecticidal nets (LLIN) use, house structural characteristics (wall type, roof type), and peridomestic variables (cooking in the house, cattle near the house, number of people sleeping in the house) with mosquito abundance in houses was quantified. Vector abundance was low (mean, 1.1 adult Anopheles per house). Proximity of larval habitats was a strong predictor of Anopheles abundance. Houses without an LLIN had more female Anopheles gambiae s.s., Anopheles arabiensis and Anopheles funestus than houses where some people used an LLIN (rate ratios, 95% CI 0.87, 0.85-0.89; 0.84, 0.82-0.86; 0.38, 0.37-0.40) and houses where everyone used an LLIN (RR, 95% CI 0.49, 0.48-0.50; 0.39, 0.39-0.40; 0.60, 0.58-0.61). Cooking in the house also reduced Anopheles abundance across all species. The number of people sleeping in the house, presence of cattle near the house

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

    Science.gov (United States)

    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.

  4. Disrupted resting-state functional architecture of the brain after 45-day simulated microgravity

    Science.gov (United States)

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

    2014-01-01

    Long-term spaceflight induces both physiological and psychological changes in astronauts. To understand the neural mechanisms underlying these physiological and psychological changes, it is critical to investigate the effects of microgravity on the functional architecture of the brain. In this study, we used resting-state functional MRI (rs-fMRI) to study whether the functional architecture of the brain is altered after 45 days of −6° head-down tilt (HDT) bed rest, which is a reliable model for the simulation of microgravity. Sixteen healthy male volunteers underwent rs-fMRI scans before and after 45 days of −6° HDT bed rest. Specifically, we used a commonly employed graph-based measure of network organization, i.e., degree centrality (DC), to perform a full-brain exploration of the regions that were influenced by simulated microgravity. We subsequently examined the functional connectivities of these regions using a seed-based resting-state functional connectivity (RSFC) analysis. We found decreased DC in two regions, the left anterior insula (aINS) and the anterior part of the middle cingulate cortex (MCC; also called the dorsal anterior cingulate cortex in many studies), in the male volunteers after 45 days of −6° HDT bed rest. Furthermore, seed-based RSFC analyses revealed that a functional network anchored in the aINS and MCC was particularly influenced by simulated microgravity. These results provide evidence that simulated microgravity alters the resting-state functional architecture of the brains of males and suggest that the processing of salience information, which is primarily subserved by the aINS–MCC functional network, is particularly influenced by spaceflight. The current findings provide a new perspective for understanding the relationships between microgravity, cognitive function, autonomic neural function, and central neural activity. PMID:24926242

  5. Disrutpted resting-state functional architecture of the brain after 45-day simulated microgravity

    Directory of Open Access Journals (Sweden)

    Yuan eZhou

    2014-06-01

    Full Text Available Long-term spaceflight induces both physiological and psychological changes in astronauts. To understand the neural mechanisms underlying these physiological and psychological changes, it is critical to investigate the effects of microgravity on the functional architecture of the brain. In this study, we used resting-state functional MRI (rs-fMRI to study whether the functional architecture of the brain is altered after 45 days of -6° head-down tilt (HDT bed rest, which is a reliable model for the simulation of microgravity. Sixteen healthy male volunteers underwent rs-fMRI scans before and after 45 days of -6° HDT bed rest. Specifically, we used a commonly employed graph-based measure of network organization, i.e., degree centrality (DC, to perform a full-brain exploration of the regions that were influenced by simulated microgravity. We subsequently examined the functional connectivities of these regions using a seed-based resting-state functional connectivity (RSFC analysis. We found decreased DC in two regions, the left anterior insula (aINS and the anterior part of the middle cingulate cortex (MCC; also called the dorsal anterior cingulate cortex in many studies, in the male volunteers after 45 days of -6° HDT bed rest. Furthermore, seed-based RSFC analyses revealed that a functional network anchored in the aINS and MCC was particularly influenced by simulated microgravity. These results provide evidence that simulated microgravity alters the resting-state functional architecture of the brains of males and suggest that the processing of salience information, which is primarily subserved by the aINS–MCC functional network, is particularly influenced by spaceflight. The current findings provide a new perspective for understanding the relationships between microgravity, cognitive function, autonomic neural function and central neural activity.

  6. Rigidity of tilting modules

    DEFF Research Database (Denmark)

    Haahr Andersen, Henning; Kaneda, Masaharu

    Let $U_q$ denote the quantum group associated with a finite dimensional semisimple Lie algebra. Assume that $q$ is a complex root of unity of odd order and that $U_q$ is %the quantum group version obtained via Lusztig's $q$-divided powers construction. We prove that all regular projective (tilting...

  7. EPA-Registered Bed Bug Products

    Science.gov (United States)

    ... rest or hide in hampers, bed frames, even furniture); Failing to treat adjacent areas where bed bugs ... to work (some pesticides, such as desiccators or growth regulators, may be very effective but take some ...

  8. RESTful NET

    CERN Document Server

    Flanders, Jon

    2008-01-01

    RESTful .NET is the first book that teaches Windows developers to build RESTful web services using the latest Microsoft tools. Written by Windows Communication Foundation (WFC) expert Jon Flanders, this hands-on tutorial demonstrates how you can use WCF and other components of the .NET 3.5 Framework to build, deploy and use REST-based web services in a variety of application scenarios. RESTful architecture offers a simpler approach to building web services than SOAP, SOA, and the cumbersome WS- stack. And WCF has proven to be a flexible technology for building distributed systems not necessa

  9. Effects of bed-load movement on flow resistance over bed forms

    Indian Academy of Sciences (India)

    Abstract. The effect of bed-load transport on flow resistance of alluvial channels with undulated bed was experimentally investigated. The experiments were carried out in a tilting flume 250mm wide and 12·5m long with glass-sides of rectan- gular cross-section and artificial dune shaped floor that was made from Plexi-glass.

  10. Bed Bugs

    Science.gov (United States)

    Prevent, identify, and treat bed bug infestations using EPA’s step-by-step guides, based on IPM principles. Find pesticides approved for bed bug control, check out the information clearinghouse, and dispel bed bug myths.

  11. Work-rate-guided exercise testing in patients with incomplete spinal cord injury using a robotics-assisted tilt-table.

    Science.gov (United States)

    Laubacher, Marco; Perret, Claudio; Hunt, Kenneth J

    2015-01-01

    Robotics-assisted tilt-table (RTT) technology allows neurological rehabilitation therapy to be started early thus alleviating some secondary complications of prolonged bed rest. This study assessed the feasibility of a novel work-rate-guided RTT approach for cardiopulmonary training and assessment in patients with incomplete spinal cord injury (iSCI). Three representative subjects with iSCI at three distinct stages of primary rehabilitation completed an incremental exercise test (IET) and a constant load test (CLT) on a RTT augmented with integrated leg-force and position measurement and visual work rate feedback. Feasibility assessment focused on: (i) implementation, (ii) limited efficacy testing, (iii) acceptability. (i) All subjects were able follow the work rate target profile by adapting their volitional leg effort. (ii) During the IETs, peak oxygen uptake above rest was 304, 467 and 1378 ml/min and peak heart rate (HR) was 46, 32 and 65 beats/min above rest (subjects A, B and C, respectively). During the CLTs, steady-state oxygen uptake increased by 42%, 38% and 162% and HR by 12%, 20% and 29%. (iii) All exercise tests were tolerated well. The novel work-rate guided RTT intervention is deemed feasible for cardiopulmonary training and assessment in patients with iSCI: substantial cardiopulmonary responses were observed and the approach was found to be tolerable and implementable. Implications for Rehabilitation Work-rate guided robotics-assisted tilt-table technology is deemed feasible for cardiopulmonary assessment and training in patients with incomplete spinal cord injury. Robotics-assisted tilt-tables might be a good way to start with an active rehabilitation as early as possible after a spinal cord injury. During training with robotics-assisted devices the active participation of the patients is crucial to strain the cardiopulmonary system and hence gain from the training.

  12. Relationship between stroke volume, cardiac output and filling of the heart during tilt

    DEFF Research Database (Denmark)

    Bundgaard-Nielsen, M.; Sorensen, H.; Dalsgaard, M.

    2009-01-01

    . With the supine resting position as a reference, we assessed stroke volume (SV), cardiac output (CO) and filling of the heart during graded tilt to evaluate whether SV and CO are maintained during an assumed maximal physiological filling of the heart elicited by 90 degrees HDT in healthy resting humans. METHODS...

  13. Source to Accretion Disk Tilt

    OpenAIRE

    Montgomery, M. M.; Martin, E. L.

    2010-01-01

    Many different system types retrogradely precess, and retrograde precession could be from a tidal torque by the secondary on a misaligned accretion disk. However, a source to cause and maintain disk tilt is unknown. In this work, we show that accretion disks can tilt due to a force called lift. Lift results from differing gas stream supersonic speeds over and under an accretion disk. Because lift acts at the disk's center of pressure, a torque is applied around a rotation axis passing through...

  14. Fluid observers and tilting cosmology

    International Nuclear Information System (INIS)

    Coley, A A; Hervik, S; Lim, W C

    2006-01-01

    We study perfect fluid cosmological models with a constant equation of state parameter γ in which there are two naturally defined timelike congruences, a geometrically defined geodesic congruence and a non-geodesic fluid congruence. We establish an appropriate set of boost formulae relating the physical variables, and consequently the observed quantities, in the two frames. We study expanding spatially homogeneous tilted perfect fluid models, with an emphasis on future evolution with extreme tilt. We show that for ultra-radiative equations of state (i.e. γ > 4/3), generically the tilt becomes extreme at late times and the fluid observers will reach infinite expansion within a finite proper time and experience a singularity similar to that of the big rip. In addition, we show that for sub-radiative equations of state (i.e. γ < 4/3), the tilt can become extreme at late times and give rise to an effective quintessential equation of state. To establish the connection with phantom cosmology and quintessence, we calculate the effective equation of state in the models under consideration and we determine the future asymptotic behaviour of the tilting models in the fluid frame variables using the boost formulae. We also discuss spatially inhomogeneous models and tilting spatially homogeneous models with a cosmological constant

  15. Tilt testing results are influenced by tilt protocol.

    Science.gov (United States)

    Zyśko, Dorota; Fedorowski, Artur; Nilsson, David; Rudnicki, Jerzy; Gajek, Jacek; Melander, Olle; Sutton, Richard

    2016-07-01

    It is unknown how the return to supine position influences duration of loss of consciousness (LOC) and cardioinhibition during tilt test. Retrospective analysis of two datasets containing records of patients who underwent tilt testing for unexplained syncope in two centres was performed. Patients, totalling 1232, were included in the study: 262 in a Swedish centre and 970 patients in a Polish centre. In Sweden, tilt table with tilt-down time (TDT) of 18 s was used (Group II). In Poland, two different tilt tables were used, one of them with TDT of 10 s (Group I, n = 325), and the other with TDT of 47 s (Group III, n = 645). Cardioinhibitory reflex occurred most frequently in Group III, whereas number of pauses >3 s, frequency of very long asystole ≥30 s, and the total duration of pauses >3 s demonstrated a trend to increase from Group I to III. Duration of LOC in Groups II and III was significantly longer compared with Group I (32.0 and 33.7 s vs. 16.4 s). In the multivariate-adjusted regression model, cardioinhibitory reflex was predicted by tilt-table model (odds ratio per model with increasing TDT: 1.40; 95% confidence interval, 1.19-1.64; P < 0.0001), whereas LOC duration was longer with increasing TDT (P < 0.0001) and age (P < 0.0001). Longer TDT during induced vasovagal syncope increases the prevalence of cardioinhibitory reflex and prolongs the duration of LOC. Tilt-down time does not affect asystolic pause duration but delay may lead to occurrence of multiple pauses, higher frequency of very long asystole, and longer total asystole duration. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

  16. Tilt measurements at Vulcano Island

    Directory of Open Access Journals (Sweden)

    B. Saraceno

    2007-06-01

    Full Text Available A network of tiltmeters has been operational on Vulcano Island for numerous years. At present, the network comprises five functioning borehole stations, four of which are installed at 8-10 m and allow recording very stable, high precision signals with very low noise. We report observations over the last 12 years that illustrate impulsive variations linked to seismicity and long-term (several years trends in the signals. We suggest a relationship between tilt changes correlated to the strongest regional seismic events and site acceleration; long-term tilt variations analyzed in combination with other ground deformation data seem to represent the evidence of a contraction of the La Fossa cone. We also analyzed how the tilt device has the capability to detect possible magma migrations; we considered previous studies that have imaged spatially well-defined levels of magma accumulation beneath La Fossa, and Vulcanello; we concluded that the Vulcano tilt network should be capable of detecting the upward migration of small magma volumes. Finally, we show that no evidence of changes are visible on tilt signals during anomalous degassing episodes (linked to a building up input of magmatic fluids at the La Fossa thereby evidencing that no magma migration occurred during such events.

  17. Tibiotalar tilt - a new slant

    Energy Technology Data Exchange (ETDEWEB)

    Griffiths, H.; Wandtke, J.

    1981-05-01

    Classically tibiotalar tilt (TTT) is associated with four conditions: Fairbanks disease, hemophilia, sickle-cell anemia and juvenile rheumatoid arthritis. We have found it to be present in at least 20 other conditions including other dysplasias, developmental conditions such as fibrous dysplasia and a variety of other acquired disorders including various metabolic diseases and following previous trauma. The pathogenesis is controversial, but the most probable cause is related to stress and the blood supply of the distal tibial epiphysis. The differentiation of TTT from pseudotibiotalar tilt is also discussed.

  18. Tilting Saturn without Tilting Jupiter: Constraints on Giant Planet Migration

    Science.gov (United States)

    Brasser, R.; Lee, Man Hoi

    2015-11-01

    The migration and encounter histories of the giant planets in our solar system can be constrained by the obliquities of Jupiter and Saturn. We have performed secular simulations with imposed migration and N-body simulations with planetesimals to study the expected obliquity distribution of migrating planets with initial conditions resembling those of the smooth migration model, the resonant Nice model and two models with five giant planets initially in resonance (one compact and one loose configuration). For smooth migration, the secular spin-orbit resonance mechanism can tilt Saturn’s spin axis to the current obliquity if the product of the migration timescale and the orbital inclinations is sufficiently large (exceeding 30 Myr deg). For the resonant Nice model with imposed migration, it is difficult to reproduce today’s obliquity values, because the compactness of the initial system raises the frequency that tilts Saturn above the spin precession frequency of Jupiter, causing a Jupiter spin-orbit resonance crossing. Migration timescales sufficiently long to tilt Saturn generally suffice to tilt Jupiter more than is observed. The full N-body simulations tell a somewhat different story, with Jupiter generally being tilted as often as Saturn, but on average having a higher obliquity. The main obstacle is the final orbital spacing of the giant planets, coupled with the tail of Neptune’s migration. The resonant Nice case is barely able to simultaneously reproduce the orbital and spin properties of the giant planets, with a probability ˜ 0.15%. The loose five planet model is unable to match all our constraints (probability <0.08%). The compact five planet model has the highest chance of matching the orbital and obliquity constraints simultaneously (probability ˜0.3%).

  19. Height and Tilt Geometric Texture

    DEFF Research Database (Denmark)

    Andersen, Vedrana; Desbrun, Mathieu; Bærentzen, Jakob Andreas

    2009-01-01

    compromise between functionality and simplicity: it can efficiently handle and process geometric texture too complex to be represented as a height field, without having recourse to full blown mesh editing algorithms. The height-and-tilt representation proposed here is fully intrinsic to the mesh, making...

  20. Tilting-connected symmetric algebras

    OpenAIRE

    Aihara, Takuma

    2010-01-01

    The notion of silting mutation was introduced by Iyama and the author. In this paper we mainly study silting mutation for self-injective algebras and prove that any representation-finite symmetric algebra is tilting-connected. Moreover we give some sufficient conditions for a Bongartz-type Lemma to hold for silting objects.

  1. Influence of forming conditions on fiber tilt

    Science.gov (United States)

    David W. Vahey; John M. Considine; Michael A. and MacGregor

    2013-01-01

    Fiber tilt describes the projection of fiber length in the thickness direction of paper. The projection is described by the tilt angle of fibers with respect to the plane of the sheet. A simple model for fiber tilt is based on jet-to-wire velocity differential in combination with cross-flows on the wire. The tilt angle of a fiber is found to vary as the sine of its in-...

  2. Realization of Tip Tilting By 8-Step Line Tilting

    International Nuclear Information System (INIS)

    Chen Yingtian; Zhang Yang; Lim, Boon Ham; Lim, Chen Sin; Hu Sen; Ho, Tso-Hsiu

    2009-01-01

    By direct calculation of rotation matrices of SO(3), we show how certain specific sequence of eight consecutive rotations of digital angles can yield a tilting of a facet mirror. We also design a detailed program specifically to tilt an array of mirrors from planar orientation to the required focusing orientation. We describe how to use the 8-step to realize the focusing of the mirror array. We have found, in our designed program, an important feature of row-sharing during the rotations for the columns and similarly the column-sharing during the rotations for the row. This feature can save a lot of operating time during the actual realization of the mechanical movements.

  3. About the gasification of untreated scrap and waste wood in fluidized bed reactor for use in decentralized gas engine-cogeneration plants; Zur Vergasung von Rest- und Abfallholz in Wirbelschichtreaktoren fuer dezentrale Energieversorgungsanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Tepper, H.

    2005-10-20

    This dissertation examines the thermochemical conversion (gasification) of untreated scrap and waste wood in combustible gases for use in decentralized gas engine-cogeneration plants of low output (1 to 10 MW fuel power). A general section goes into the basics of the energetic utilization of solid biomass, the subprocesses of thermochemical conversion being described in more detail. Special attention is given to the processes and state of the art of biomass gasification in decentralized plants. A theoretical section analyzes the gasification models for solid biomass presented in the literature. Based on this analysis, a simplified kinetic model is derived for the gasification of untreated scrap and waste wood with air in bubbling fluidized bed reactors. It includes a fluid mechanic analysis of the fluidized bed based on HILLIGARDT, an empirical pyrolysis model and a global kinetic approach to the main chemical reaction taken from the literature. An experimental section describes the tests of the gasification of forest scrap wood in a semi-industrial fluidized bed gasification test plant with 150 kW fuel power and presents the significant test results. The gasification model derived is applied to check the test plant's standard settings and compare them with measured values. Furthermore, the model is employed to explain basic reaction paths and zones and to perform concluding parameter simulations. (orig.)

  4. Reducing friction in tilting-pad bearings by the use of enclosed recesses

    DEFF Research Database (Denmark)

    Heinrichson, Niels; Santos, Ilmar

    2008-01-01

    A three-dimensional thermoelastohydrodynamic model is applied to the analysis of tilting-pad bearings with spherical pivots and equipped with deep recesses in the high-pressure regions. A potential for a 10-20% reduction in the friction loss compared to conventional plain bearing pads is documented....... Design suggestions minimizing the power loss are given for various length-to-width ratios. The tilting angle in the sliding direction is more sensitive to correct positioning of the pivot point than conventional bearing pads. Improving the performance by equipping a tilting-pad bearing with a deep recess...... therefore requires accurate analysis and design of the bearing. Similarly, a high sensitivity perpendicular to the sliding direction suggests that this method of reducing friction is more feasible when using line pivots or spring beds than when using spherical pivots for controlling the tilting angle....

  5. Tilt measurements at Vulcano Island

    OpenAIRE

    B. Saraceno; G. Laudani; F. Guglielmino; A. Ferro; G. Falzone; O. Campisi; S. Gambino

    2007-01-01

    A network of tiltmeters has been operational on Vulcano Island for numerous years. At present, the network comprises five functioning borehole stations, four of which are installed at 8-10 m and allow recording very stable, high precision signals with very low noise. We report observations over the last 12 years that illustrate impulsive variations linked to seismicity and long-term (several years) trends in the signals. We suggest a relationship between tilt changes correlated to the stro...

  6. Effects of Vestibular Loss on Orthostatic Responses to Tilts in the Pitch Plane

    Science.gov (United States)

    Wood, Scott J.; Serrador, Jorge M.; Black, F. Owen; Rupert,Angus H.; Schlegel, Todd T.

    2004-01-01

    The purpose of this study was to determine the extent to which vestibular loss might impair orthostatic responses to passive tilts in the pitch plane in human subjects. Data were obtained from six subjects having chronic bilateral vestibular loss and six healthy individuals matched for age, gender, and body mass index. Vestibular loss was assessed with a comprehensive battery including dynamic posturography, vestibulo-ocular and optokinetic reflexes, vestibular evoked myogenic potentials, and ocular counterrolling. Head up tilt tests were conducted using a motorized two-axis table that allowed subjects to be tilted in the pitch plane from either a supine or prone body orientation at a slow rate (8 deg/s). The sessions consisted of three tilts, each consisting of20 min rest in a horizontal position, tilt to 80 deg upright for 10 min, and then return to the horizontal position for 5 min. The tilts were performed in darkness (supine and prone) or in light (supine only). Background music was used to mask auditory orientation cues. Autonomic measurements included beat-to-beat recordings of blood pressure (Finapres), heart rate (ECG), cerebral blood flow velocity in the middle cerebral artery (transcranial Doppler), end tidal CO2, respiratory rate and volume (Respritrace), and stroke volume (impedance cardiography). For both patients and control subjects, cerebral blood flow appeared to exhibit the most rapid adjustment following transient changes in posture. Outside of a greater cerebral hypoperfusion in patients during the later stages of tilt, responses did not differ dramatically between the vestibular loss and control subjects, or between tilts performed in light and dark room conditions. Thus, with the 'exception of cerebrovascular regulation, we conclude that orthostatic responses during slow postural tilts are not substantially impaired in humans following chronic loss of vestibular function, a result that might reflect compensation by nonvisual graviceptor

  7. Tilted cranking classification of multibandspectra

    Energy Technology Data Exchange (ETDEWEB)

    Frauendorf, S [IHK F2-Rossendorf, Dresden (Germany); [Lawrence Berkeley Lab., CA (United States); May, F R [Niels Bohr Inst., Copenhagen (Denmark); [Lund Univ. (Sweden). Dept. of Mathematical Physics

    1992-08-01

    The tilted cranking theory of multi-band spectra of deformed nuclei is discussed. The existence of TDHF (time-dependent Hartree Fock) solutions rotating uniformly about a non-principal axis of the deformed axial potential is demonstrated. The solutions represent {Delta}I=1 bands. Self-consistency and symmetry are discussed. The transfer of experimental spectra to the rotating field of reference is introduced. Excitation spectra at high spin are calculated, and found to agree well with recent data on {sup 163}Er and {sup 174}Hf. 7 refs., 5 figs.

  8. Molecular tilt on monolayer-protected nanoparticles

    KAUST Repository

    Giomi, L.

    2012-02-01

    The structure of the tilted phase of monolayer-protected nanoparticles is investigated by means of a simple Ginzburg-Landau model. The theory contains two dimensionless parameters representing the preferential tilt angle and the ratio ε between the energy cost due to spatial variations in the tilt of the coating molecules and that of the van der Waals interactions which favors the preferential tilt. We analyze the model for both spherical and octahedral particles. On spherical particles, we find a transition from a tilted phase, at small ε, to a phase where the molecules spontaneously align along the surface normal and tilt disappears. Octahedral particles have an additional phase at small ε characterized by the presence of six topological defects. These defective configurations provide preferred sites for the chemical functionalization of monolayer-protected nanoparticles via place-exchange reactions and their consequent linking to form molecules and bulk materials. Copyright © EPLA, 2012.

  9. Molecular tilt on monolayer-protected nanoparticles

    KAUST Repository

    Giomi, L.; Bowick, M. J.; Ma, X.; Majumdar, A.

    2012-01-01

    The structure of the tilted phase of monolayer-protected nanoparticles is investigated by means of a simple Ginzburg-Landau model. The theory contains two dimensionless parameters representing the preferential tilt angle and the ratio ε between the energy cost due to spatial variations in the tilt of the coating molecules and that of the van der Waals interactions which favors the preferential tilt. We analyze the model for both spherical and octahedral particles. On spherical particles, we find a transition from a tilted phase, at small ε, to a phase where the molecules spontaneously align along the surface normal and tilt disappears. Octahedral particles have an additional phase at small ε characterized by the presence of six topological defects. These defective configurations provide preferred sites for the chemical functionalization of monolayer-protected nanoparticles via place-exchange reactions and their consequent linking to form molecules and bulk materials. Copyright © EPLA, 2012.

  10. REST based mobile applications

    Science.gov (United States)

    Rambow, Mark; Preuss, Thomas; Berdux, Jörg; Conrad, Marc

    2008-02-01

    Simplicity is the major advantage of REST based webservices. Whereas SOAP is widespread in complex, security sensitive business-to-business aplications, REST is widely used for mashups and end-user centric applicatons. In that context we give an overview of REST and compare it to SOAP. Furthermore we apply the GeoDrawing application as an example for REST based mobile applications and emphasize on pros and cons for the use of REST in mobile application scenarios.

  11. Tilting Uranus without a Collision

    Science.gov (United States)

    Rogoszinski, Zeeve; Hamilton, Douglas P.

    2016-10-01

    The most accepted hypothesis for the origin of Uranus' 98° obliquity is a giant collision during the late stages of planetary accretion. This model requires a single Earth mass object striking Uranus at high latitudes; such events occur with a probability of about 10%. Alternatively, Uranus' obliquity may have arisen from a sequence of smaller impactors which lead to a uniform distribution of obliquities. Here we explore a third model for tilting Uranus using secular spin-orbit resonance theory. We investigate early Solar System configurations in which a secular resonance between Uranus' axial precession frequency and another planet's orbital node precession frequency might occur.Thommes et al. (1999) hypothesized that Uranus and Neptune initially formed between Jupiter and Saturn, and were then kicked outward. In our scenario, Neptune leaves first while Uranus remains behind. As an exterior Neptune slowly migrates outward, it picks up both Uranus and Saturn in spin-orbit resonances (Ward and Hamilton 2004; Hamilton and Ward 2004). Only a distant Neptune has a nodal frequency slow enough to resonate with Uranus' axial precession.This scenario, with diverging orbits, results in resonance capture. As Neptune migrates outward its nodal precession slows. While in resonance, Uranus and Saturn each tilt a bit further, slowing their axial precession rates to continually match Neptune's nodal precession rate. Tilting Uranus to high obliquities takes a few 100 Myrs. This timescale may be too long to hold Uranus captive between Jupiter and Saturn, and we are investigating how to reduce it. We also find that resonance capture is rare if Uranus' initial obliquity is greater than about 10°, as the probability of capture decreases as the planet's initial obliquity increases. We will refine this estimate by quantifying capture statistics, and running accretion simulations to test the likelihood of a low early obliquity. Our preliminary findings show that most assumptions about

  12. Large optics inspection, tilting, and washing stand

    Science.gov (United States)

    Ayers, Marion Jay [Brentwood, CA; Ayers, Shannon Lee [Brentwood, CA

    2010-08-24

    A large optics stand provides a risk free means of safely tilting large optics with ease and a method of safely tilting large optics with ease. The optics are supported in the horizontal position by pads. In the vertical plane the optics are supported by saddles that evenly distribute the optics weight over a large area.

  13. Lake-tilting investigations in southern Sweden

    International Nuclear Information System (INIS)

    Paasse, T.

    1996-04-01

    The main aim of lake-tilting investigations is to determine the course of the glacio-isostatic uplift, i.e. to find a formula for the uplift. Besides the lake-tilting graphs, knowledge of the recent relative uplift and the gradient of some marine shorelines are used for solving this problem. This paper summarizes four investigations. 23 refs, 10 figs

  14. Optic flow induced self-tilt perception

    NARCIS (Netherlands)

    Bos, J.E.

    2008-01-01

    Roll optic flow induces illusory self-tilt in humans. As far as the mechanism underlying this visual-vestibular interaction is understood, larger angles of self-tilt are predicted than observed. It is hypothesized that the discrepancy can be explained by idiotropic (i.e., referring to a personal

  15. Alternative REST Splicing Underappreciated

    OpenAIRE

    Chen, Guo-Lin; Miller, Gregory

    2017-01-01

    As a major orchestrator of the cellular epigenome, the repressor element-1 silencing transcription factor (REST) can either repress or activate thousands of genes depending on cellular context, suggesting a highly context-dependent REST function tuned by environmental cues. While REST shows cell-type non-selective active transcription, an N-terminal REST4 isoform caused by alternative splicing - inclusion of an extra exon (N3c) which introduces a pre-mature stop codon - has been implicated in...

  16. Tilting mode in field-reversed configurations

    International Nuclear Information System (INIS)

    Schwarzmeier, J.L.; Barnes, D.C.; Lewis, H.R.; Seyler, C.E.; Shestakov, A.I.

    1982-01-01

    Field Reversed Configurations (FRCs) experimentally have exhibited remarkable stability on the magnetohydrodynamic (MHD) timescale, despite numerous MHD calculations showing FRCs to be unstable. It is easy to believe that local modes are stabilized by finite Larmor radius (FLR) effects, but more puzzling is the apparent stability of FRCs against global modes, where one would expect FLR effects to be less important. In this paper we study the tilting mode, which MHD has shown to be a rapidly growing global mode. The tilting mode in FRCs is driven by the pressure gradient, and magnetic compression and field line bending are the stabilizing forces. A schematic of the evolution of the tilting mode is shown. The tilting mode is considered dangerous, because it would lead to rapid tearing across the separatrix. Unlike spheromaks, the tilting mode in FRCs has a separatrix that is fixed in space, so that the mode is strictly internal

  17. Optimum Tilt Angle at Tropical Region

    Directory of Open Access Journals (Sweden)

    S Soulayman

    2015-02-01

    Full Text Available : One of the important parameters that affect the performance of a solar collector is its tilt angle with the horizon. This is because of the variation of tilt angle changes the amount of solar radiation reaching the collector surface. Meanwhile, is the rule of thumb, which says that solar collector Equator facing position is the best, is valid for tropical region? Thus, it is required to determine the optimum tilt as for Equator facing and for Pole oriented collectors. In addition, the question that may arise: how many times is reasonable for adjusting collector tilt angle for a definite value of surface azimuth angle? A mathematical model was used for estimating the solar radiation on a tilted surface, and to determine the optimum tilt angle and orientation (surface azimuth angle for the solar collector at any latitude. This model was applied for determining optimum tilt angle and orientation in the tropical zones, on a daily basis, as well as for a specific period. The optimum angle was computed by searching for the values for which the radiation on the collector surface is a maximum for a particular day or a specific period. The results reveal that changing the tilt angle 12 times in a year (i.e. using the monthly optimum tilt angle maintains approximately the total amount of solar radiation near the maximum value that is found by changing the tilt angle daily to its optimum value. This achieves a yearly gain in solar radiation of 11% to 18% more than the case of a solar collector fixed on a horizontal surface.

  18. Unilateral otolith centrifugation by head tilt.

    Science.gov (United States)

    Winters, Stephanie M; Bos, Jelte E; Klis, Sjaak F L

    2014-01-01

    To test for otolith asymmetries, several studies described horizontal translation of the body and head en bloc during fast vertical axis rotation. This stimulus causes one otolithic organ to rotate on-axis, and the other to experience centripetal acceleration. To test a new, more simple method of unilateral stimulation with head tilt and the body remaining on axis. During stationary and during 360 deg/s rotation, 12 healthy blindfolded subjects had their heads tilted 30 degrees sideways, positioning one otolithic organ on the axis of rotation after the other. The haptic subjective vertical (SV) was recorded several times by means of a manually adjustable rod. It was found that during stationary the SV tilted about 4 degrees on average in the direction of the head. During rotation, the SV tilted about 9 degrees on average. We therefore estimate the effect of eccentric otolith rotation to be 5 degrees on average. Tilt of the subjective vertical induced by head tilt during on-axis body rotation can provide a relatively uncomplicated alternative to test unilateral otolithic function as compared to body and head translation during rotation. Moreover, unlike eccentric rotation of the entire body, somatosensory cues are minimized by keeping the body fixed on axis and by subtracting the effect of head tilt per se.

  19. Evaluating Tilt for Wind Farms: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Annoni, Jennifer; Scholbrock, Andrew; Churchfield, Matthew; Fleming, Paul

    2017-06-29

    The objective of this work is to demonstrate the feasibility of tilt in a wind plant. Tilt control, much like other wind plant control strategies, has the potential to improve the performance of a wind plant. Tilt control uses the tilt angle of the turbine to direct the wake above or below the downstream turbines. This paper presents a study of tilt in two- and threeturbine arrays. Specifically, the authors show that the power production of a two-turbine array can be increased by tilting turbines in a specific orientation. When adding more turbines, as is shown with the three-turbine array, the overall percentage of power gain increases. This outcome deviates from some of the results seen in typical wind plant control strategies. Finally, we discuss the impact this type of control strategy has on the aerodynamics in a wind plant. This analysis demonstrates that a good understanding of wake characteristics is necessary to improve the plant's performance. A tilt strategy such as the one presented in this paper may have implications for future control/optimization studies including optimization of hub heights in a wind plant and analysis of deep array effects.

  20. CT patellar cortex tilt angle: A radiological method to measure patellar tilt

    International Nuclear Information System (INIS)

    Mirza Toluei, F.; Afshar, A.; Salarilak, S.; Sina, A.

    2005-01-01

    Background/Objectives: the role of patellar tilt in the anterior knee pain is indisputable. Traditionally. the lateral patello-femoral angle of Laurin has been defined in both the axial view and CT images for measuring the tilt of patella. We present a new angle. which is independent of the morphology of patella and directly relates to clinical assessment of the tilt. which is appreciated from palpation of the edges of the patella. Patients and Methods: 38 patients with anterior knee pain and forty normal control subjects were examined using CT scan of patello-femoral joint in 15 degrees of knee flexion. The amount of lateral patellar tilt was quantitatively assessed using the lateral patello-femoral angle, as described by Laurin et al, and the newly defined patellar cortex tilt angle. This angle is subtended by the line drawn along the posterior femoral condyles and the one parallel to the subchondral bone of patellar cortex. The fifteen-degree tilt was taken as normal cut-off point for patellar cortex tilt angle in the control group. Results: in patients, the average tilt of patella. using the patellar cortex tilt angle was 15.26 versus 7.05 in the control group. Using Student's t test, the difference between the two means was significant (P<0.001). The sensitivity and specificity of patellar cortex tilt angle were 40 and 90 percent, respectively There was a moderate agreement between our presented test and the lateral tilt angle test (kappa=0.40. P<0.001). Conclusion: our results indicate that patellar tilt can also be detected using patellar cortex tilt angle. We need more specific studies ta determine the validity of the test

  1. The relation between tilt table and acceleration-tolerance and their dependence on stature and physical fitness

    Science.gov (United States)

    Klein, K. E.; Backhausen, F.; Bruner, H.; Eichhorn, J.; Jovy, D.; Schotte, J.; Vogt, L.; Wegman, H. M.

    1980-01-01

    A group of 12 highly trained athletes and a group of 12untrained students were subjected to passive changes of position on a tilt table and positive accelerations in a centrifuge. During a 20 min tilt, including two additional respiratory maneuvers, the number of faints and average cardiovascular responses did not differ significantly between the groups. During linear increase of acceleration, the average blackout level was almost identical in both groups. Statistically significant coefficients of product-moment correlation for various relations were obtained. The coefficient of multiple determination computed for the dependence of acceleration tolerance on heart-eye distance and systolic blood pressure at rest allows the explanation of almost 50% of the variation of acceleration tolerance. The maximum oxygen uptake showed the expected significant correlation to the heart rate at rest, but not the acceleration tolerance, or to the cardiovascular responses to tilting.

  2. Dynamic of charged planar geometry in tilted and non-tilted frames

    Energy Technology Data Exchange (ETDEWEB)

    Sharif, M., E-mail: msharif.math@pu.edu.pk; Zaeem Ul Haq Bhatti, M., E-mail: mzaeem.math@pu.edu.pk [University of the Punjab, Department of Mathematics (Pakistan)

    2015-05-15

    We investigate the dynamics of charged planar symmetry with an anisotropic matter field subject to a radially moving observer called a tilted observer. The Einstein-Maxwell field equations are used to obtain a relation between non-tilted and tilted frames and between kinematical and dynamical quantities. Using the Taub mass formalism and conservation laws, two evolution equations are developed to analyze the inhomogeneities in the tilted congruence. It is found that the radial velocity (due to the tilted observer) and the electric charge have a crucial effect on the inhomogeneity factor. Finally, we discuss the stability in the non-tilted frame in the pure diffusion case and examine the effects of the electromagnetic field.

  3. Spheromak tilting and its stability control

    International Nuclear Information System (INIS)

    Hayashi, T.; Sato, T.

    1983-01-01

    Spheromak tilting instability was studied. A numerical technique to create a rather arbitrarily-shaped spheromak like the one with a flux hole was investigated. The dynamics governing the tilting instability, namely, the influence of the magnetic index, the toroidal current (q-profile) and the resistivity upon the tilting growth rate, and the roles of magnetc reconnection upon the nonlinear development were studied. The best way to control the tilting instability was invented. The stabilizing effects of the vertical wall, the isolated conducting cylindrical belt, and the horizontal wall were studied. Central pole stabilization was also investigated. The influence of the wall condition, namely, whether the wall acted as a flux conserver in the spheromak creation stage or not is discussed. The present study has shown that the three- dimensional simulation is indeed useful and practical in not only studying the underlying physics but also finding a stabilization technique of spheromaks. (Kato, T.)

  4. Tilt angles and positive response of head-up tilt test in children with orthostatic intolerance.

    Science.gov (United States)

    Lin, Jing; Wang, Yuli; Ochs, Todd; Tang, Chaoshu; Du, Junbao; Jin, Hongfang

    2015-01-01

    This study aimed at examining three tilt angle-based positive responses and the time to positive response in a head-up tilt test for children with orthostatic intolerance, and the psychological fear experienced at the three angles during head-up tilt test. A total of 174 children, including 76 boys and 98 girls, aged from 4 to 18 years old (mean 11.3±2.8 years old), with unexplained syncope, were randomly divided into three groups, to undergo head-up tilt test at the angles of 60°, 70° and 80°, respectively. The diagnostic rates and times were analysed, and Wong-Baker face pain rating scale was used to access the children's psychological fear. There were no significant differences in diagnostic rates of postural orthostatic tachycardia syndrome and vasovagal syncope at different tilt angles during the head-up tilt test (p>0.05). There was a significant difference, however, in the psychological fear at different tilt angles utilising the Kruskal-Wallis test (χ2=36.398, ptest (ptest for vasovagal syncope or for postural orthostatic tachycardia syndrome. Hence, it is suggested that a tilt angle of 60° and head-up tilt test time of 45 minutes should be suitable for children with vasovagal syncope.

  5. Decreased distensibility of a passive vascular bed in diabetes mellitus

    DEFF Research Database (Denmark)

    Faris, I; Agerskov, K; Henrikson, O

    1982-01-01

    exercise and (b) in a vascular bed locally paralysed by the injection of papaverine. Five normal subjects, six patients with long-standing Type 1 diabetes and six non-diabetic patients with severe atherosclerosis affecting the legs were studied. Blood flow was measured in the anterior tibial muscle......This study was undertaken to determine whether the distensibility of a passive vascular bed is reduced in Type 1 (insulin-dependent) diabetic patients with microangiopathy. The change in blood flow induced by 45 degrees head-up tilting was studied in two systems: (a) following maximal ischaemic...... by the isotope washout technique. The median increase in blood flow produced by tilting was greater in normal subjects than in diabetic subjects in both the locally-relaxed bed (58% and 14% respectively) and after maximal ischaemic exercise (45% and 4% respectively). In the atherosclerotic subjects, the increase...

  6. Lifting to cluster-tilting objects in higher cluster categories

    OpenAIRE

    Liu, Pin

    2008-01-01

    In this note, we consider the $d$-cluster-tilted algebras, the endomorphism algebras of $d$-cluster-tilting objects in $d$-cluster categories. We show that a tilting module over such an algebra lifts to a $d$-cluster-tilting object in this $d$-cluster category.

  7. Is Rest Really Rest? Resting State Functional Connectivity during Rest and Motor Task Paradigms.

    Science.gov (United States)

    Jurkiewicz, Michael T; Crawley, Adrian P; Mikulis, David J

    2018-04-18

    Numerous studies have identified the default mode network (DMN) within the brain of healthy individuals, which has been attributed to the ongoing mental activity of the brain during the wakeful resting-state. While engaged during specific resting-state fMRI paradigms, it remains unclear as to whether traditional block-design simple movement fMRI experiments significantly influence the default mode network or other areas. Using blood-oxygen level dependent (BOLD) fMRI we characterized the pattern of functional connectivity in healthy subjects during a resting-state paradigm and compared this to the same resting-state analysis performed on motor task data residual time courses after regressing out the task paradigm. Using seed-voxel analysis to define the DMN, the executive control network (ECN), and sensorimotor, auditory and visual networks, the resting-state analysis of the residual time courses demonstrated reduced functional connectivity in the motor network and reduced connectivity between the insula and the ECN compared to the standard resting-state datasets. Overall, performance of simple self-directed motor tasks does little to change the resting-state functional connectivity across the brain, especially in non-motor areas. This would suggest that previously acquired fMRI studies incorporating simple block-design motor tasks could be mined retrospectively for assessment of the resting-state connectivity.

  8. Direct cone beam SPECT reconstruction with camera tilt

    International Nuclear Information System (INIS)

    Jianying Li; Jaszczak, R.J.; Greer, K.L.; Coleman, R.E.; Zongjian Cao; Tsui, B.M.W.

    1993-01-01

    A filtered backprojection (FBP) algorithm is derived to perform cone beam (CB) single-photon emission computed tomography (SPECT) reconstruction with camera tilt using circular orbits. This algorithm reconstructs the tilted angle CB projection data directly by incorporating the tilt angle into it. When the tilt angle becomes zero, this algorithm reduces to that of Feldkamp. Experimentally acquired phantom studies using both a two-point source and the three-dimensional Hoffman brain phantom have been performed. The transaxial tilted cone beam brain images and profiles obtained using the new algorithm are compared with those without camera tilt. For those slices which have approximately the same distance from the detector in both tilt and non-tilt set-ups, the two transaxial reconstructions have similar profiles. The two-point source images reconstructed from this new algorithm and the tilted cone beam brain images are also compared with those reconstructed from the existing tilted cone beam algorithm. (author)

  9. Woman skeletal muscle transcriptome with bed rest and countermeasures.

    Data.gov (United States)

    National Aeronautics and Space Administration — Microgravity has a dramatic impact on human physiology illustrated in particular with skeletal muscle impairment. A thorough understanding of the mechanisms leading...

  10. RESTful Web Services Cookbook

    CERN Document Server

    Allamaraju, Subbu

    2010-01-01

    While the REST design philosophy has captured the imagination of web and enterprise developers alike, using this approach to develop real web services is no picnic. This cookbook includes more than 100 recipes to help you take advantage of REST, HTTP, and the infrastructure of the Web. You'll learn ways to design RESTful web services for client and server applications that meet performance, scalability, reliability, and security goals, no matter what programming language and development framework you use. Each recipe includes one or two problem statements, with easy-to-follow, step-by-step i

  11. Behavior of Tilted Angle Shear Connectors

    Science.gov (United States)

    Khorramian, Koosha; Maleki, Shervin; Shariati, Mahdi; Ramli Sulong, N. H.

    2015-01-01

    According to recent researches, angle shear connectors are appropriate to transfer longitudinal shear forces across the steel-concrete interface. Angle steel profile has been used in different positions as L-shaped or C-shaped shear connectors. The application of angle shear connectors in tilted positions is of interest in this study. This study investigates the behaviour of tilted-shaped angle shear connectors under monotonic loading using experimental push out tests. Eight push-out specimens are tested to investigate the effects of different angle parameters on the ultimate load capacity of connectors. Two different tilted angles of 112.5 and 135 degrees between the angle leg and steel beam are considered. In addition, angle sizes and lengths are varied. Two different failure modes were observed consisting of concrete crushing-splitting and connector fracture. By increasing the size of connector, the maximum load increased for most cases. In general, the 135 degrees tilted angle shear connectors have a higher strength and stiffness than the 112.5 degrees type. PMID:26642193

  12. Behavior of Tilted Angle Shear Connectors.

    Directory of Open Access Journals (Sweden)

    Koosha Khorramian

    Full Text Available According to recent researches, angle shear connectors are appropriate to transfer longitudinal shear forces across the steel-concrete interface. Angle steel profile has been used in different positions as L-shaped or C-shaped shear connectors. The application of angle shear connectors in tilted positions is of interest in this study. This study investigates the behaviour of tilted-shaped angle shear connectors under monotonic loading using experimental push out tests. Eight push-out specimens are tested to investigate the effects of different angle parameters on the ultimate load capacity of connectors. Two different tilted angles of 112.5 and 135 degrees between the angle leg and steel beam are considered. In addition, angle sizes and lengths are varied. Two different failure modes were observed consisting of concrete crushing-splitting and connector fracture. By increasing the size of connector, the maximum load increased for most cases. In general, the 135 degrees tilted angle shear connectors have a higher strength and stiffness than the 112.5 degrees type.

  13. Vortex trapping by tilted columnar defects

    International Nuclear Information System (INIS)

    Baladie, I.; Buzdin, A.

    2000-01-01

    The irradiation of high-T c superconductors by inclined heavy-ion beam can create columnar defects (CD's) practically at any angle towards the crystal c axis. We calculate the energy of a tilted vortex trapped on an inclined columnar defect within the framework of an electromagnetic model. Under a weak perpendicular magnetic field, and if the CD radius is larger than the superconducting coherence length, vortices always prefer to be on a tilted CD than to be aligned along the external field. We calculate also the interaction energy between two tilted vortices and find that large attractive regions appear. In particular, in the plane defined by c axis and the CD axis, tilted vortices attract each other at long distances, leading to the formation of vortex chains. The equilibrium distance between vortices in a chain is of the order of the magnitude of the in-plane London penetration depth. The existence of the inclined trapped vortices could be revealed by torque measurements, and could also lead to the anisotropy of the in-plane resistivity and the critical current

  14. "Happiness and Education": Tilting at Windmills?

    Science.gov (United States)

    Verducci, Susan

    2013-01-01

    This essay explores the question: Is Nel Noddings a visionary who sees past the constraints of contemporary education or is she, like Don Quixote, madly tilting at windmills in her description and defense of happiness as an educational aim? Viewing the educational aim of happiness as an ideal raises substantial challenges for the practicality of…

  15. Reduced Sympathetic Response to Head-Up Tilt in Subjects with Mild Cognitive Impairment or Mild Alzheimer's Dementia

    Directory of Open Access Journals (Sweden)

    Marte Rognstad Mellingsæter

    2015-03-01

    Full Text Available Background: Hemodynamic control was compared in patients with mild cognitive impairment (MCI or mild Alzheimer's dementia (AD as well as in healthy elderly subjects. Methods: Noninvasive, continuous hemodynamic recordings were obtained from 14 patients and 48 controls during supine rest (tilt of 30 and 70°. Cardiac output, end-diastolic volume, total peripheral resistance, heart rate variability (HRV, systolic blood pressure variability (SBPV, and baroreceptor sensitivity were calculated. Results: At 70° tilt, the HRV indices differed significantly, with higher high-frequency (HF variability as well as lower low-frequency (LF variability and LF/HF ratios in the patients. The patients had significantly lower SBPV in the LF range at 30° tilt. Conclusions: The results indicate a poorer sympathetic response to orthostatic stress in MCI and mild AD.

  16. REST based service composition

    DEFF Research Database (Denmark)

    Grönvall, Erik; Ingstrup, Mads; Pløger, Morten

    2011-01-01

    This paper presents an ongoing work developing and testing a Service Composition framework based upon the REST architecture named SECREST. A minimalistic approach have been favored instead of a creating a complete infrastructure. One focus has been on the system's interaction model. Indeed, an aim...

  17. Design and Development of Tilting Rotary Furnace

    Science.gov (United States)

    Sai Varun, V.; Tejesh, P.; Prashanth, B. N.

    2018-02-01

    Casting is the best and effective technique used for manufacturing products. The important accessory for casting is furnace. Furnace is used to melt the metal. A perfect furnace is one that reduces the wastage of material, reduces the cost of manufacturing and there by reduces the cost of production. Of all the present day furnaces there may be wastage of material, and the chances of increasing the time of manufacturing as the is continuous need of tilting of the furnace for every mould and then changing the moulds. Considering these aspects, a simple and least expensive tilting rotary furnace is designed and developed. The Tilting and Rotary Furnace consists of mainly melting chamber and the base. The metal enters the melting chamber through the input door that is provided on the top of the melting chamber. Inside the melting chamber there is a graphite furnace. The metal is melted in the graphite crucible. An insulation of ceramic fibre cloth is provided inside the furnace. The metal is melted using Propane gas. The propane gas is easily available and economic. The gas is burned using a pilot burner. The pilot burner is more efficient that other burners. The pilot burner is lit with a push button igniter. The pilot burner is located at the bottom of the combustion chamber. This enables the uniform heating of the metal inside the crucible. The temperature inside the melting chamber is noted using a temperature sensor. The gas input is cut-off if the temperature is exceeding a specific temperature. After the melting of the metal is done the furnace is tilted and after the mould is filled it is rotated. The external gears are used to controlling the tilting. The results of studies carried out for the design & development of low cost, simple furnace that can be mounted anywhere on the shop floor and this can be very much useful for the education purposes and small scale manufacturing. The furnace can be rotated in 360 degrees and can help in reducing the time taken

  18. Granular controls on the dispersion of bed load tracers

    Science.gov (United States)

    Jerolmack, D. J.; Martin, R. L.; Phillips, C. B.

    2014-12-01

    Coarse particles are transported in a river as bed load, i.e., they move in frequent contact with and are supported by the granular bed. This movement is typically intermittent and may be described by a series of steps are rests, the distributions of which determine particle dispersion. Laboratory and field studies of bed load tracer dispersion have reported sub- and super-diffusive behavior, both of which have been successfully reproduced with stochastic transport models. Although researchers have invoked heavy-tailed step lengths as the cause of anomalous dispersion, most observations report thin-tailed distributions. Little attention has been paid to rest periods, and stochastic transport models have not been connected to the underlying mechanics of particle motion. Based on theoretical and experimental evidence, we argue that step lengths are thin-tailed and do not control the longterm dispersion of bed load tracers; they are determined by momentum balance between the fluid and solid. Using laboratory experiments with both marbles and natural sediments, we demonstrate that the rest time distribution is power law, and argue that this distribution controls asymptotic dispersion. Observed rest times far exceed any hydrodynamic timescale. Experiments reveal that rest times of deposited particles are governed by fluctuations in river bed elevation; in particular, the return time for the bed to scour to the base of a deposited particle. Stochastic fluctuations in bed elevation are describable by an Ornstein-Uhlenbeck (mean-reverting random walk) model that contains two parameters, which we show are directly related to the granular shear rate and range of bed elevation fluctuations, respectively. Combining these results with the theory of asymmetric random walks (particles only move downstream), we predict superdiffusive behavior that is in quantitative agreement with our observations of tracer dispersion in a natural river.

  19. Resting behaviour of Anopheles gambiae s.l. and its implication on ...

    African Journals Online (AJOL)

    An entomological survey to determine resting behaviour and species composition of malaria vectors was carried out in Uyui District in western Tanzania in May 2009. Mosquitoes were collected using indoor resting catch, window exit trap and outdoor “bed-net” techniques. They mosquitoes were identified using ...

  20. A tilted transversely isotropic slowness surface approximation

    KAUST Repository

    Stovas, A.

    2012-05-09

    The relation between vertical and horizontal slownesses, better known as the dispersion relation, for transversely isotropic media with a tilted symmetry axis (TTI) requires solving a quartic polynomial equation, which does not admit a practical explicit solution to be used, for example, in downward continuation. Using a combination of the perturbation theory with respect to the anelliptic parameter and Shanks transform to improve the accuracy of the expansion, we develop an explicit formula for the vertical slowness that is highly accurate for all practical purposes. It also reveals some insights into the anisotropy parameter dependency of the dispersion relation including the low impact that the anelliptic parameter has on the vertical placement of reflectors for a small tilt in the symmetry angle. © 2012 European Association of Geoscientists & Engineers.

  1. Coherent field propagation between tilted planes.

    Science.gov (United States)

    Stock, Johannes; Worku, Norman Girma; Gross, Herbert

    2017-10-01

    Propagating electromagnetic light fields between nonparallel planes is of special importance, e.g., within the design of novel computer-generated holograms or the simulation of optical systems. In contrast to the extensively discussed evaluation between parallel planes, the diffraction-based propagation of light onto a tilted plane is more burdensome, since discrete fast Fourier transforms cannot be applied directly. In this work, we propose a quasi-fast algorithm (O(N 3  log N)) that deals with this problem. Based on a proper decomposition into three rotations, the vectorial field distribution is calculated on a tilted plane using the spectrum of plane waves. The algorithm works on equidistant grids, so neither nonuniform Fourier transforms nor an explicit complex interpolation is necessary. The proposed algorithm is discussed in detail and applied to several examples of practical interest.

  2. Interplay between tilted and principal axis rotation

    International Nuclear Information System (INIS)

    Datta, Pradip; Roy, Santosh; Chattopadhyay, S.

    2014-01-01

    At IUAC-INGA, our group has studied four neutron rich nuclei of mass-110 region, namely 109,110 Ag and 108,110 Cd. These nuclei provide the unique platform to study the interplay between Tilted and Principal axis rotation since these are moderately deformed and at the same time, shears structures are present at higher spins. The salient features of the high spin behaviors of these nuclei will be discussed which are the signatures of this interplay

  3. Interplay between tilted and principal axis rotation

    Energy Technology Data Exchange (ETDEWEB)

    Datta, Pradip [Ananda Mohan College, 102/1 Raja Rammohan Sarani, Kolkata 700 009 (India); Roy, Santosh; Chattopadhyay, S. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700 064 (India)

    2014-08-14

    At IUAC-INGA, our group has studied four neutron rich nuclei of mass-110 region, namely {sup 109,110}Ag and {sup 108,110}Cd. These nuclei provide the unique platform to study the interplay between Tilted and Principal axis rotation since these are moderately deformed and at the same time, shears structures are present at higher spins. The salient features of the high spin behaviors of these nuclei will be discussed which are the signatures of this interplay.

  4. Inner core tilt and polar motion

    Science.gov (United States)

    Dumberry, Mathieu; Bloxham, Jeremy

    2002-11-01

    A tilted inner core permits exchange of angular momentum between the core and the mantle through gravitational and pressure torques and, as a result, changes in the direction of Earth's axis of rotation with respect to the mantle. We have developed a model to calculate the amplitude of the polar motion that results from an equatorial torque at the inner core boundary which tilts the inner core out of alignment with the mantle. We specifically address the issue of the role of the inner core tilt in the decade polar motion known as the Markowitz wobble. We show that a decade polar motion of the same amplitude as the observed Markowitz wobble requires a torque of 1020 N m which tilts the inner core by 0.07 degrees. This result critically depends on the viscosity of the inner core; for a viscosity less than 5 × 1017 Pa s, larger torques are required. We investigate the possibility that a torque of 1020 N m with decadal periodicity can be produced by electromagnetic coupling between the inner core and torsional oscillations of the flow in the outer core. We demonstrate that a radial magnetic field at the inner core boundary of 3 to 4 mT is required to obtain a torque of such amplitude. The resulting polar motion is eccentric and polarized, in agreement with the observations. Our model suggests that equatorial torques at the inner core boundary might also excite the Chandler wobble, provided there exists a physical mechanism that can generate a large torque at a 14 month period.

  5. Substorm onset location and dipole tilt angle

    Directory of Open Access Journals (Sweden)

    J. Wanliss

    2006-03-01

    Full Text Available From an initial data set of over 200 substorms we have studied a subset of 30 magnetospheric substorms close to magnetic midnight to investigate, in a statistical fashion, the source region of the auroral arc that brightens at the onset of expansive phase. This arc is usually identified as the ionospheric signature of the expansive phase onset that occurs in the magnetotail. All the substorm onsets were identified via ground-based magnetometer and photometer data from the CANOPUS array. Various Tsyganenko global magnetic field models were used to map magnetic field lines from the location of the onset arc out to its greatest radial distance in the magnetotail. The results appear to favour the current disruption model of substorms since the average onset location has an average of 14.1 Earth radii (RE and is therefore more consistent with theories that place the onset location in the inner magnetotail. For the narrow range of tilts available our modeling indicates the parameter that appears to strongly influence the location of the substorm onset is the dipole tilt angle; as tilt becomes less negative onsets occur further downtail.

  6. A COMMON SOURCE OF ACCRETION DISK TILT

    International Nuclear Information System (INIS)

    Montgomery, M. M.; Martin, E. L.

    2010-01-01

    Many different system types retrogradely precess, and retrograde precession could be from a tidal torque by the secondary on a misaligned accretion disk. However, a source that causes and maintains disk tilt is unknown. In this work, we show that accretion disks can tilt due to a force called lift. Lift results from differing gas stream supersonic speeds over and under an accretion disk. Because lift acts at the disk's center of pressure, a torque is applied around a rotation axis passing through the disk's center of mass. The disk responds to lift by pitching around the disk's line of nodes. If the gas stream flow ebbs, then lift also ebbs and the disk attempts to return to its original orientation. To first approximation, lift does not depend on magnetic fields or radiation sources but does depend on the mass and the surface area of the disk. Also, for disk tilt to be initiated, a minimum mass transfer rate must be exceeded. For example, a 10 -11 M sun disk around a 0.8 M sun compact central object requires a mass transfer rate greater than ∼ 8 x 10 -11 M sun yr -1 , a value well below the known mass transfer rates in cataclysmic variable dwarf novae systems that retrogradely precess and exhibit negative superhumps in their light curves and a value well below mass transfer rates in protostellar-forming systems.

  7. Practice Hospital Bed Safety

    Science.gov (United States)

    ... Home For Consumers Consumer Updates Practice Hospital Bed Safety Share Tweet Linkedin Pin it More sharing options ... It depends on the complexity of the bed." Safety Tips CDRH offers the following safety tips for ...

  8. Bed Bugs and Schools

    Science.gov (United States)

    Bed bugs have long been a pest – feeding on blood, causing itchy bites and generally irritating their human hosts. They are successful hitchhikers, and can move from an infested site to furniture, bedding, baggage, boxes, and clothing.

  9. High Maturity Is Not a Procrustean Bed

    Science.gov (United States)

    2014-07-01

    for public release; distribution unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT In Greek mythology , Procrustes was a rogue smith and bandit who...Institute of Technology Jo Ann Lane, University of Southern California Supannika Koolmanojwong, University of Southern California Abstract. In Greek ... mythology , Procrustes was a rogue smith and bandit who invited travellers to rest in his “perfectly sized bed.” When they accepted, he forcibly bound

  10. Conservative treatment of excessive anterior pelvic tilt

    DEFF Research Database (Denmark)

    Brekke, Anders Falk

    of Clinical Research, University of Southern Denmark, Denmark 3Department of Physiotherapy, University College Zealand, Denmark 4Center for Evidence-Based Medicine, Odense University Hospital, Denmark Correspondence Anders Falk Brekke E-mail: afbrekke@health.sdu.dk Mob: +45 7248 2626 Add: Sdr. Boulevard 29......Conservative treatment of excessive anterior pelvic tilt: A systematic review Anders Falk Brekke1,2,3, Søren Overgaard1,2, Asbjørn Hróbjartsson4, Anders Holsgaard-Larsen1,2 1Orthopaedic Research Unit, Department of Orthopaedic Surgery and Traumatology, Odense University Hospital 2Department...

  11. Thermal annealing of tilted fiber Bragg gratings

    Science.gov (United States)

    González-Vila, Á.; Rodríguez-Cobo, L.; Mégret, P.; Caucheteur, C.; López-Higuera, J. M.

    2016-05-01

    We report a practical study of the thermal decay of cladding mode resonances in tilted fiber Bragg gratings, establishing an analogy with the "power law" evolution previously observed on uniform gratings. We examine how this process contributes to a great thermal stability, even improving it by means of a second cycle slightly increasing the annealing temperature. In addition, we show an improvement of the grating spectrum after annealing, with respect to the one just after inscription, which suggests the application of this method to be employed to improve saturation issues during the photo-inscription process.

  12. [Renin-angiotensin-aldosterone system activity during head-up tilt testing in patients with vasovagal syncope].

    Science.gov (United States)

    Gajek, Jacek; Zyśko, Dorota; Mazurek, Walentyna

    2005-08-01

    The stimulation of renin-angiotensin-aldosterone (RAA) system during tilt table test is caused by sympathetic nervous system activation by orthostatic stress and a serotonin release as well. In healthy individuals increase of plasma renin activity during test with maximal values on the peak of the test was described. The aim of the study was to assess the activation of RAAS in patients with neurally mediated syncope during the tilt table test by means of plasma renin activity and serum aldosterone levels. The study was carried out in 31 patients aged 39.4 +/- 15.0 years (18 women and 13 men) with neurally mediated syncope during tilt test. Plasma renin activity was assessed in the baseline conditions, immediately after the test and 10 minutes after the test using radioenzymatic assay. Aldosterone concentrations were measured radioimmunologically, twice: after 30 minutes supine rest and after the syncope. Plasma renin activity during supine rest was 2.2 +/- 2.4 ng/ml/h, rose after the syncope 2.5-fold to 5.2 +/- 4.5 ng/ml/h (p < 0.001 comparing to baseline) stayed on similar level approximately for the next 10 minutes--4.9 +/- 5.5 ng/ml/h (p = n.s.). In 11 patients (35%) 10 minutes after the test even further increase of PRA was observed. Serum aldosterone level increased significantly immediately after tilt test (90.0 +/- 72.9 vs 178.8 +/- 150.1 pg/ml, p < 0.01). Authors showed, that in patients with NMS plasma renin activity increases and this increase lasts for 10 minutes after the syncope and the concentration of aldosterone increases immediately after tilt test.

  13. An efficient eikonal solver for tilted transversely isotropic and tilted orthorhombic media

    KAUST Repository

    Waheed, Umair bin

    2014-01-01

    Computing first-arrival traveltimes in the presence of anisotropy is important for high-end near surface modeling, microseismic source localization, and fractured reservoir characterization. Anisotropy deviating from elliptical anisotropy introduces higher-order nonlinearity into the eikonal equation, which makes solving the equation a challenging task. We address this challenge by iteratively solving a sequence of simpler tilted elliptically anisotropic eikonal equations. At each iteration, the source function is updated to capture the effects due to the higher order nonlinear terms in the anisotropy. We use Aitken extrapolation to speed up the convergence rate of the iterative algorithm. The result is an efficient algorithm for firstarrival traveltime computations in tilted anisotropic media. We demonstrate the proposed method for the tilted transversely isotropic media and the tilted orthorhombic media. Numerical tests show that the proposed method is feasible and produces results that are comparable to wavefield extrapolation, even for strongly anisotropic and complex structures. Therefore, for the cases where one or two-point ray tracing fails, our method may be a potential substitute for computing traveltimes.

  14. Rotating Shaft Tilt Angle Measurement Using an Inclinometer

    OpenAIRE

    Luo Jun; Wang Zhiqian; Shen Chengwu; Wen Zhuoman; Liu Shaojin; Cai Sheng; Li Jianrong

    2015-01-01

    This paper describes a novel measurement method to accurately measure the rotating shaft tilt angle of rotating machine for alignment or compensation using a dual-axis inclinometer. A model of the rotating shaft tilt angle measurement is established using a dual-axis inclinometer based on the designed mechanical structure, and the calculation equation between the rotating shaft tilt angle and the inclinometer axes outputs is derived under the condition that the inclinometer axes are perpendic...

  15. Numerical modelling of the tilt casting processes of titanium alumindes

    OpenAIRE

    Wang, Hong

    2008-01-01

    This research has investigated the modelling and optimisation of the tilt casting process of Titanium Aluminides (TiAl). This study is carried out in parallel with the experimental research undertaken in IRC at the University of Birmingham. They propose to use tilt casting inside a vacuum chamber and attempt to combine this tilt casting process with Induction Skull Melting (ISM). A totally novel process is developing for investment casting, which is suitable for casting gamma TiAl.\\ud \\ud As ...

  16. Mapping of moveout in tilted transversely isotropic media

    KAUST Repository

    Stovas, A.; Alkhalifah, Tariq Ali

    2013-01-01

    The computation of traveltimes in a transverse isotropic medium with a tilted symmetry axis tilted transversely isotropic is very important both for modelling and inversion. We develop a simple analytical procedure to map the traveltime function from a transverse isotropic medium with a vertical symmetry axis (vertical transversely isotropic) to a tilted transversely isotropic medium by applying point-by-point mapping of the traveltime function. This approach can be used for kinematic modelling and inversion in layered tilted transversely isotropic media. © 2013 European Association of Geoscientists & Engineers.

  17. Transient cardio-respiratory responses to visually induced tilt illusions

    Science.gov (United States)

    Wood, S. J.; Ramsdell, C. D.; Mullen, T. J.; Oman, C. M.; Harm, D. L.; Paloski, W. H.

    2000-01-01

    Although the orthostatic cardio-respiratory response is primarily mediated by the baroreflex, studies have shown that vestibular cues also contribute in both humans and animals. We have demonstrated a visually mediated response to illusory tilt in some human subjects. Blood pressure, heart and respiration rate, and lung volume were monitored in 16 supine human subjects during two types of visual stimulation, and compared with responses to real passive whole body tilt from supine to head 80 degrees upright. Visual tilt stimuli consisted of either a static scene from an overhead mirror or constant velocity scene motion along different body axes generated by an ultra-wide dome projection system. Visual vertical cues were initially aligned with the longitudinal body axis. Subjective tilt and self-motion were reported verbally. Although significant changes in cardio-respiratory parameters to illusory tilts could not be demonstrated for the entire group, several subjects showed significant transient decreases in mean blood pressure resembling their initial response to passive head-up tilt. Changes in pulse pressure and a slight elevation in heart rate were noted. These transient responses are consistent with the hypothesis that visual-vestibular input contributes to the initial cardiovascular adjustment to a change in posture in humans. On average the static scene elicited perceived tilt without rotation. Dome scene pitch and yaw elicited perceived tilt and rotation, and dome roll motion elicited perceived rotation without tilt. A significant correlation between the magnitude of physiological and subjective reports could not be demonstrated.

  18. Mapping of moveout in tilted transversely isotropic media

    KAUST Repository

    Stovas, A.

    2013-09-09

    The computation of traveltimes in a transverse isotropic medium with a tilted symmetry axis tilted transversely isotropic is very important both for modelling and inversion. We develop a simple analytical procedure to map the traveltime function from a transverse isotropic medium with a vertical symmetry axis (vertical transversely isotropic) to a tilted transversely isotropic medium by applying point-by-point mapping of the traveltime function. This approach can be used for kinematic modelling and inversion in layered tilted transversely isotropic media. © 2013 European Association of Geoscientists & Engineers.

  19. Advection and dispersion of bed load tracers

    Science.gov (United States)

    Lajeunesse, Eric; Devauchelle, Olivier; James, François

    2018-05-01

    We use the erosion-deposition model introduced by Charru et al. (2004) to numerically simulate the evolution of a plume of bed load tracers entrained by a steady flow. In this model, the propagation of the plume results from the stochastic exchange of particles between the bed and the bed load layer. We find a transition between two asymptotic regimes. The tracers, initially at rest, are gradually set into motion by the flow. During this entrainment regime, the plume is strongly skewed in the direction of propagation and continuously accelerates while spreading nonlinearly. With time, the skewness of the plume eventually reaches a maximum value before decreasing. This marks the transition to an advection-diffusion regime in which the plume becomes increasingly symmetrical, spreads linearly, and advances at constant velocity. We analytically derive the expressions of the position, the variance, and the skewness of the plume and investigate their asymptotic regimes. Our model assumes steady state. In the field, however, bed load transport is intermittent. We show that the asymptotic regimes become insensitive to this intermittency when expressed in terms of the distance traveled by the plume. If this finding applies to the field, it might provide an estimate for the average bed load transport rate.

  20. Dipoles at rest

    International Nuclear Information System (INIS)

    Griffiths, D.J.

    1992-01-01

    In a world populated by magnetic monopoles (as well as ordinary electric charges), there are two kinds of electric dipoles: those due to separated electric charges, and those due to current loops of magnetic charge. Similarly, there are two kinds of magnetic dipoles: those due to separated magnetic monopoles, and those due to electric current loops. This paper derives the potentials and fields of each of the four dipole species, and calculates the force, torque, energy, momentum, and angular momentum of each type, when placed (at rest) in a static external field (which may itself be produced by electric charges and currents, magnetic charges and currents, or all of these). Some implications and applications of the various results are discussed

  1. Fluid-bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, G.; Schoebotham, N.

    1981-02-01

    In Energy Equipment Company's two-stage fluidized bed system, partial combustion in a fluidized bed is followed by burn-off of the generated gases above the bed. The system can be retrofitted to existing boilers, and can burn small, high ash coal efficiently. It has advantages when used as a hot gas generator for process drying. Tests on a boiler at a Cadbury Schweppes plant are reported.

  2. Fluidised bed combustion system

    International Nuclear Information System (INIS)

    McKenzie, E.C.

    1976-01-01

    Fluidized bed combustion systems that facilitates the maintenance of the depth of the bed are described. A discharge pipe projects upwardly into the bed so that bed material can flow into its upper end and escape downwardly. The end of the pipe is surrounded by an enclosure and air is discharged into the enclosure so that material will enter the pipe from within the enclosure and have been cooled in the enclosure by the air discharged into it. The walls of the enclosure may themselves be cooled

  3. Using collisions and resonances to tilting Uranus

    Science.gov (United States)

    Rogoszinski, Zeeve; Hamilton, Douglas

    2018-01-01

    Uranus’ large obliquity (98°) is widely thought to have occurred from a polar strike with an Earth sized object. Morbidelli et al. (2012) argue that two or more collisions are required in order to explain the prograde motion of Uranus’ satellites. These impactors could have been less massive by about a factor of ten, but multiple polar strikes are still improbable as even larger mass impactors would be needed for more equatorial collisions. Here we explore an alternative non-collisional model inspired by the explanation to Saturn’s significant tilt (27°). Ward and Hamilton (2004) & Hamilton and Ward (2004) argue that a secular resonance currently between Saturn’s spin axis and Neptune’s orbital pole is responsible for Saturn’s large obliquity. Unfortunately, Uranus’ axial precession frequency today is too long to match any of the current planets’ fundamental frequencies. Boué and Laskar (2010) explain that Uranus may have harbored an improbably large moon in the past which could have sped up the planet’s axial precession frequency enough to resonate with the regression of its own orbital pole. We explore another scenario which requires only the interactions between the giant planets.Thommes et al. (1999, 2002, 2003) argue that at least the cores of Uranus and Neptune were formed in between Jupiter and Saturn, as the density of the protoplanetary disk was greater there. If Neptune was scattered outward before Uranus, then a secular spin-orbit resonance between the two planets is possible. However, driving Uranus’ obliquity to near 90° with a resonance capture requires a timescale on the order of 100 Myr. If Neptune migrated out quicker or its orbital inclination was initially larger, then we find that the resulting resonance kick can tilt Uranus more than 40° in a reasonable timespan. This could replace one of the impactors required in the collisional scenario described by Morbidelli et al. (2012), but in most situations the effect of such a

  4. Rats Housed on Corncob Bedding Show Less Slow-Wave Sleep

    OpenAIRE

    Leys, Laura J; McGaraughty, Steve; Radek, Richard J

    2012-01-01

    Despite the reported advantages of corncob bedding, questions have emerged about how comfortable animals find this type of bedding as a resting surface. In this study, encephalography (EEG) was used to compare the effects of corncob and aspen-chip bedding on rat slow-wave sleep (SWS). According to a facility-wide initiative, rats that were weaned on aspen-chip bedding were switched to corncob bedding in home cages and EEG recording chambers. Spontaneous EEG recordings obtained for 5 wk after ...

  5. [Electromechanical registration of the resting behavior of fattening pigs].

    Science.gov (United States)

    Heuser, H; Plonait, H

    1977-10-05

    The resting behaviour of four weanling pigs has been continuously recorded by an electromechanical apparatus for 8 weeks. The duration of different postures: standing, ventral recumbency, lateral recumbency and frequency of standing periods were recorded as influenced by different environmental factors. 1. Floor with and without bedding at 21 degrees C. 2. Floor without bedding at 27 degrees C environmental temperature. 3. Feeding once daily versus twice. Duration of recumbency periods was increases at 21 degrees C if bedding was provided. This also improved daily gain. At elevated environmental temperatures the animals preferred the lying posture on concrete floor. Feeding twice increased the duration of recumbency. The same was the case as the animals grew older. Disturbance by caretaking activities in neighbouring dens increased the duration of standing.

  6. Tensor products of quantized tilting modules

    International Nuclear Information System (INIS)

    Andersen, H.H.

    1992-01-01

    Let U k denote the quantized enveloping algebra corresponding to a finite dimensional simple complex Lie algebra L. Assume that the quantum parameter is a root of unity in k of order at least the Coxeter number for pound. Also assume that this order is odd and not divisible by 3 if type G 2 occurs. We demonstrate how one can define a reduced tensor product on the family F consisting of those finite dimensional simple U k -modules which are deformations of simple L-modules and which have non-zero quantum dimension. This together with the work of Reshetikhin-Turaev and Turaev-Wenzl prove that (U k , F) is a modular Hopf algebra and hence produces invariants of 3-manifolds. Also by recent work of Duurhus, Jakobsen and Nest it leads to a general topological quantum field theory. The method of proof explores quantized analogues of tilting modules for algebraic groups. (orig.)

  7. Lens decenter and tilt measurement by interferogram

    Science.gov (United States)

    Hung, Min-Wei; Wu, Wen-Hong; Huang, Kuo-Cheng

    2009-11-01

    For the recent years, the vigorous development of the electro-optic industry, particularly the digital camera and the cellular phone camera, has placed a larger and larger demand for the optical devices. Among the optical lens, the aspherical optical lens plays the key component because the aspherical lens may provide better imaging quality then the spherical lens does. For the manufacturing reason, the aspherical lens is prone to a decenter or tilt issue with respect to the optical axes of its two surfaces. To measure decenter and tile error specifically would help to obviate the deficient lens, but most of the present measuring method can't provide this function. This paper proposed a new method to specifically measure the decenter and tile of lens by observing the interferogram of each surface. And the corresponding measuring instrument, which contains interferometer and motion stages, was introduced as well.

  8. Tilted-ring modelling of disk galaxies : Anomalous gas

    NARCIS (Netherlands)

    Jozsa, G. I. G.; Niemczyk, C.; Klein, U.; Oosterloo, T. A.

    We report our ongoing work on kinematical modelling of HI in disk galaxies. We employ our new software TiRiFiC (Tilted-Ring-Fitting-Code) in order to derive tilted-ring models by fitting artificial HI data cubes to observed ones in an automated process. With this technique we derive very reliable

  9. Angular momentum projection of tilted axis rotating states

    Energy Technology Data Exchange (ETDEWEB)

    Oi, M; Onishi, N; Tajima, N [Tokyo Univ. (Japan); Horibata, T

    1998-03-01

    We applied an exact angular momentum projection to three dimensional cranked HFB (3d-CHFB) states. Tilted axis rotating states (TAR) and principal axis rotating states (PAR) are compared. It is shown that TAR is more adequate than PAR for description of the back bending phenomena driven by tilted rotation or wobbling motion. (author)

  10. Modelling and simulation of a compliant tilting pad air bearing

    NARCIS (Netherlands)

    Duijnhouwer, F.; Nijmeijer, H.

    The compliant tilting pad air bearing concept, a tilting pad bearing with the pivot of the pads placed on radial springs, is a promising aerodynamic bearing solution. Nevertheless, its non-linear dynamics make a time domain dynamic simulation model an essential tool for the design of rotor systems

  11. Fluidized bed incinerator development

    International Nuclear Information System (INIS)

    Ziegler, D.L.; Johnson, A.J.

    1976-01-01

    A fluidized bed incinerator is being developed for burning rad contaminated solid and liquid waste materials. In situ neutralization of acid gases by the bed material, catalytic afterburning, and gas filtration are used to produce a clean flue gas without the use of aqueous scrubbing

  12. DIRAC RESTful API

    International Nuclear Information System (INIS)

    Casajus Ramo, A; Graciani Diaz, R; Tsaregorodtsev, A

    2012-01-01

    The DIRAC framework for distributed computing has been designed as a flexible and modular solution that can be adapted to the requirements of any community. Users interact with DIRAC via command line, using the web portal or accessing resources via the DIRAC python API. The current DIRAC API requires users to use a python version valid for DIRAC. Some communities have developed their own software solutions for handling their specific workload, and would like to use DIRAC as their back-end to access distributed computing resources easily. Many of these solutions are not coded in python or depend on a specific python version. To solve this gap DIRAC provides a new language agnostic API that any software solution can use. This new API has been designed following the RESTful principles. Any language with libraries to issue standard HTTP queries may use it. GSI proxies can still be used to authenticate against the API services. However GSI proxies are not a widely adopted standard. The new DIRAC API also allows clients to use OAuth for delegating the user credentials to a third party solution. These delegated credentials allow the third party software to query to DIRAC on behalf of the users. This new API will further expand the possibilities communities have to integrate DIRAC into their distributed computing models.

  13. LONG-TERM MEASUREMENTS OF SUNSPOT MAGNETIC TILT ANGLES

    Energy Technology Data Exchange (ETDEWEB)

    Li Jing [Department of Earth and Space Sciences, University of California at Los Angeles, Los Angeles, CA 90095-1567 (United States); Ulrich, Roger K., E-mail: jli@igpp.ucla.edu [Department of Physics and Astronomy, University of California at Los Angeles, Los Angeles, CA 90095-1567 (United States)

    2012-10-20

    Tilt angles of close to 30,600 sunspots are determined using Mount Wilson daily averaged magnetograms taken from 1974 to 2012, and SOHO/MDI magnetograms taken from 1996 to 2010. Within a cycle, more than 90% of sunspots have a normal polarity alignment along the east-west direction following Hale's law. The median tilts increase with increasing latitude (Joy's law) at a rate of {approx}0.{sup 0}5 per degree of latitude. Tilt angles of spots appear largely invariant with respect to time at a given latitude, but they decrease by {approx}0.{sup 0}9 per year on average, a trend that largely reflects Joy's law following the butterfly diagram. We find an asymmetry between the hemispheres in the mean tilt angles. On average, the tilts are greater in the Southern than in the Northern Hemisphere for all latitude zones, and the differences increase with increasing latitude.

  14. Optimum tilt angle and orientation for solar collectors in Syria

    International Nuclear Information System (INIS)

    Skeiker, Kamal

    2009-01-01

    One of the important parameters that affect the performance of a solar collector is its tilt angle with the horizon. This is because of the variation of tilt angle changes the amount of solar radiation reaching the collector surface. A mathematical model was used for estimating the solar radiation on a tilted surface, and to determine the optimum tilt angle and orientation (surface azimuth angle) for the solar collector in the main Syrian zones, on a daily basis, as well as for a specific period. The optimum angle was computed by searching for the values for which the radiation on the collector surface is a maximum for a particular day or a specific period. The results reveal that changing the tilt angle 12 times in a year (i.e. using the monthly optimum tilt angle) maintains approximately the total amount of solar radiation near the maximum value that is found by changing the tilt angle daily to its optimum value. This achieves a yearly gain in solar radiation of approximately 30% more than the case of a solar collector fixed on a horizontal surface.

  15. A Horizontal Tilt Correction Method for Ship License Numbers Recognition

    Science.gov (United States)

    Liu, Baolong; Zhang, Sanyuan; Hong, Zhenjie; Ye, Xiuzi

    2018-02-01

    An automatic ship license numbers (SLNs) recognition system plays a significant role in intelligent waterway transportation systems since it can be used to identify ships by recognizing the characters in SLNs. Tilt occurs frequently in many SLNs because the monitors and the ships usually have great vertical or horizontal angles, which decreases the accuracy and robustness of a SLNs recognition system significantly. In this paper, we present a horizontal tilt correction method for SLNs. For an input tilt SLN image, the proposed method accomplishes the correction task through three main steps. First, a MSER-based characters’ center-points computation algorithm is designed to compute the accurate center-points of the characters contained in the input SLN image. Second, a L 1- L 2 distance-based straight line is fitted to the computed center-points using M-estimator algorithm. The tilt angle is estimated at this stage. Finally, based on the computed tilt angle, an affine transformation rotation is conducted to rotate and to correct the input SLN horizontally. At last, the proposed method is tested on 200 tilt SLN images, the proposed method is proved to be effective with a tilt correction rate of 80.5%.

  16. Motion perception during tilt and translation after space flight

    Science.gov (United States)

    Clément, Gilles; Wood, Scott J.

    2013-11-01

    Preliminary results of an ongoing study examining the effects of space flight on astronauts' motion perception induced by independent tilt and translation motions are presented. This experiment used a sled and a variable radius centrifuge that translated the subjects forward-backward or laterally, and simultaneously tilted them in pitch or roll, respectively. Tests were performed on the ground prior to and immediately after landing. The astronauts were asked to report about their perceived motion in response to different combinations of body tilt and translation in darkness. Their ability to manually control their own orientation was also evaluated using a joystick with which they nulled out the perceived tilt while the sled and centrifuge were in motion. Preliminary results confirm that the magnitude of perceived tilt increased during static tilt in roll after space flight. A deterioration in the crewmember to control tilt using non-visual inertial cues was also observed post-flight. However, the use of a tactile prosthesis indicating the direction of down on the subject's trunk improved manual control performance both before and after space flight.

  17. Slow sedimentary processes on-a-chip: experiments on porous flow effects on granular bed creep

    Science.gov (United States)

    Houssais, M.; Maldarelli, C.; Shattuck, M.; Morris, J. F.

    2017-12-01

    Steep soils dynamics is hard to catch. they exhibit very slow granular creep most of the time, and sometimes, mostly under or after rain, turn into a landslide, a very fast avalanche flow.The conditions of transition from soil creep to avalanching remains a lot non-understood, and Safe Factor law (empirical criteria, function of rain intensity and duration). On another side, in marine fast deposition environments, compaction drives vertical porous flow, which makes bed shear resistance change, and form over time bed size patterns (pipes, dishes) or mechanical heterogeneities.Capturing how the slow creep dynamics depends on the porous flow would allow for much more accurate landscape evolution modeling.We present here preliminary results of an experimental investigation of one the major triggering condition for soils destabilization: rain infiltration, and more generally porous flow through a tilted granular bed. In a quasi-2D microfluidics channel, a flat sediment bed made of spherical particles is prepared, in fully submerged condition. It is thereafter tilted (at slope under critical slope of avalanching) and simultaneously put under vertical weak porous flow (well under the critical flow of liquefaction regarding positive pressure gradients). The two control parameters are varied, and local particles concentration and motion are measured. Interestingly, although staying in the sub-critical creeping regime, we observe an acceleration of the bed deformation downward, as the porous flow and the bed slope are increased, until the criteria for avalanching is reached. Those results appear to present similitudes with the case of tilted dry sediment bed under controlled vibrations. Consequently it opens the discussion about a potential universal model of landslides triggering due to frequent seismological and rainstorm events.

  18. Tilt sensor and servo control system for gravitational wave detection

    CERN Document Server

    Cheng, Y; Ju, L; Blair, D G

    2002-01-01

    This paper describes the design of a novel double-flexure two-axis tilt sensor with a tilt readout based on an optical walk-off sensor. The performance of the device has been investigated theoretically and experimentally. The walk-off sensor has demonstrated a sensitivity of 10 sup - sup 1 sup 1 rad Hz sup - sup 1 sup / sup 2 at 1 Hz. The tilt sensor has measured seismic noise approx 10 sup - sup 9 -10 sup - sup 1 sup 0 rad Hz sup - sup 1 sup / sup 2 for frequency in the 2-10 Hz range.

  19. Bed Bugs FAQs

    Science.gov (United States)

    ... Europe. Bed bugs have been found in five-star hotels and resorts and their presence is not ... Health – Division of Parasitic Diseases Email Recommend Tweet YouTube Instagram Listen Watch RSS ABOUT About CDC Jobs ...

  20. Bed Bug Information Clearinghouse

    Science.gov (United States)

    Its purpose is to help states, communities, and consumers in efforts to prevent and control bed bug infestations. Currently includes only reviewed material from federal/state/local government agencies, extension services, and universities.

  1. Particle fuel bed tests

    International Nuclear Information System (INIS)

    Horn, F.L.; Powell, J.R.; Savino, J.M.

    1985-01-01

    Gas-cooled reactors, using packed beds of small diameter coated fuel particles have been proposed for compact, high-power systems. The particulate fuel used in the tests was 800 microns in diameter, consisting of a thoria kernel coated with 200 microns of pyrocarbon. Typically, the bed of fuel particles was contained in a ceramic cylinder with porous metallic frits at each end. A dc voltage was applied to the metallic frits and the resulting electric current heated the bed. Heat was removed by passing coolant (helium or hydrogen) through the bed. Candidate frit materials, rhenium, nickel, zirconium carbide, and zirconium oxide were unaffected, while tungsten and tungsten-rhenium lost weight and strength. Zirconium-carbide particles were tested at 2000 K in H 2 for 12 hours with no visible reaction or weight loss

  2. EMF-REST: Generation of RESTful APIs from Models

    OpenAIRE

    Hamza , Ed-Douibi; Cánovas Izquierdo , Javier Luis; Gómez , Abel; Tisi , Massimo; Cabot , Jordi

    2016-01-01

    In the last years, RESTful Web services have become more and more popular as a lightweight solution to connect remote systems in distributed and Cloud-based architectures. However, being an architectural style rather than a specification or standard, the proper design of RESTful Web services is not trivial since developers have to deal with a plethora of recommendations and best practices. Model-Driven Engineering (MDE) emphasizes the use of models and model transformations to raise the level...

  3. determination of determination of optimal tilt angle for maximum

    African Journals Online (AJOL)

    eobe

    Keywords: Energy output, photovoltaic module, best tilt angle, solar radiation, sunshine hours, ambient temperature. 1. .... at any given time is vital in the design of a PV system. The solar ..... [8] E. Taymur, Photovoltaic System Sizing [thesis].

  4. Downward continuation and tilt derivative of magnetic data for ...

    Indian Academy of Sciences (India)

    S K Pal

    2017-06-12

    Jun 12, 2017 ... Downward continuation; tilt derivative; magnetic data; coal fire mapping; Jharia coal field;. India. 1. .... of seams are thin and not suitable for mining but have the ...... Theory and Application; McGraw Hill Education (India).

  5. The effects of lateral head tilt on ocular astigmatic axis

    Directory of Open Access Journals (Sweden)

    Hamid Fesharaki

    2014-01-01

    Conclusion: Any minimal angle of head tilt may cause erroneous measurement of astigmatic axis and should be avoided during refraction. One cannot rely on the compensatory function of ocular counter-torsion during the refraction.

  6. Correlation between length and tilt of lipid tails

    Science.gov (United States)

    Kopelevich, Dmitry I.; Nagle, John F.

    2015-10-01

    It is becoming recognized from simulations, and to a lesser extent from experiment, that the classical Helfrich-Canham membrane continuum mechanics model can be fruitfully enriched by the inclusion of molecular tilt, even in the fluid, chain disordered, biologically relevant phase of lipid bilayers. Enriched continuum theories then add a tilt modulus κθ to accompany the well recognized bending modulus κ. Different enrichment theories largely agree for many properties, but it has been noticed that there is considerable disagreement in one prediction; one theory postulates that the average length of the hydrocarbon chain tails increases strongly with increasing tilt and another predicts no increase. Our analysis of an all-atom simulation favors the latter theory, but it also shows that the overall tail length decreases slightly with increasing tilt. We show that this deviation from continuum theory can be reconciled by consideration of the average shape of the tails, which is a descriptor not obviously includable in continuum theory.

  7. Tilted Lemaitre-Tolman-Bondi spacetimes: Hydrodynamic and thermodynamic properties

    International Nuclear Information System (INIS)

    Herrera, L.; Di Prisco, A.; Ibanez, J.

    2011-01-01

    We consider Lemaitre-Tolman-Bondi spacetimes from the point of view of a tilted observer, i.e. one with respect to which the fluid is radially moving. The imperfect fluid and the congruence described by its four-velocity, as seen by the tilted observer, is studied in detail. It is shown that from the point of view of such tilted observer, the fluid evolves nonreversibly (i.e. with nonvanishing rate of entropy production). The nongeodesic character of the tilted congruence is related to the nonvanishing of the divergence of the 4-vector entropy flow. We determine the factor related to the existence of energy-density inhomogeneities and describe its evolution; these results are compared with those obtained for the nontilted observer. Finally, we exhibit a peculiar situation where the nontilted congruence might be unstable.

  8. Anterior Hip Subluxation due to Lumbar Degenerative Kyphosis and Posterior Pelvic Tilt

    Directory of Open Access Journals (Sweden)

    Hiroyuki Tsuchie

    2014-01-01

    Full Text Available Nontraumatic anterior subluxation and dislocation of the hip joint are extremely rare. A 58-year-old woman presented to our outpatient clinic with left hip pain with a duration of 15 years. There was no history of trauma or other diseases. Her hip pain usually occurred only on walking and not at rest. Physical examinations demonstrated no tenderness in the hip joint. The range of motion of both hip joints was almost normal. Laxity of other joints was not observed. The bone mineral density of the lumbar spine and proximal femur confirmed a diagnosis of osteoporosis. A plain radiograph showed osteoarthritic changes of the hip joints, severe posterior pelvic tilt, and superior displacement of both femoral heads, especially in a standing position. Three-dimensional computed tomography (3DCT revealed anterior subluxation of both femoral heads. Seven years after the initial visit, both hip joints showed progression to severe osteoarthritis. Although the exact cause remains unclear, lumbar kyphosis, posterior pelvic tilt, and a decrease in acetabular coverage may have influenced the current case. We should be aware of these factors when we examine patients with hip osteoarthritis.

  9. The Evaluation of Usefulness of the Manufactured DTAB (Double Tilt Angle Board) System

    International Nuclear Information System (INIS)

    Lee, Joung Jin; Jang, In Gi; Kim, Wan Sun

    2006-01-01

    To resolution of A hospital-handmade modification double tilt angle immobilization system (DTAB immobilization system) and to report the clinical results of it. It was developed in conjunction with the breast board for patients unable to achieve and maintain the desired uncomfortable respiration and position of set-up needed in the treatment of RT (This custom design provides an alternative to accomplishing this desired head angle needed to relax position treatment area, realizing that the lenses totally protected eye-ball out) By using the angled breast board and SBDD(small bowel device), reproducibility of set-up and patient comfort were addressed throughout the simulation, computed tomography planning and treatment process. Usually patients the error range-within 5 mm. When use of Aqua patients error range-within 3 mm. It was constructed in tandem with a unique custom-built double tilt angle board (DTAB). It was designed to eliminate clinical set-up problems with head immobilization and instability during treatment, thus providing for a more comfortable head rest for the patient.

  10. Construction and Deployment of Tilt Sensors along the Lateral Margins of Jarvis Glacier, Alaska to improve understanding of the Deformation Regime of Wet-Based Polythermal Glaciers

    Science.gov (United States)

    Lee, I. R.; Hawley, R. L.; Clemens-Sewall, D.; Campbell, S. W.; Waszkiewicz, M.; Bernsen, S.; Gerbi, C. C.; Kreutz, K. J.; Koons, P. O.

    2017-12-01

    Most studies of natural ice have been on bodies of ice with frozen beds which experience minimal lateral shear strain, to the exclusion of polythermal ice sheets & glaciers which due to their mixed basal thermal regime have wet-based beds. The deficiency in knowledge and understanding of the operative deformation mechanisms of wet-based bodies of ice results in uncertainty in the constitutive flow law of ice. Given that the flow law was derived experimentally under assumptions more conducive to bodies of ice with frozen-based beds, it is necessary to calibrate the flow law when applied to different bodies of ice such as wet-based polythermal glaciers. To this end, Dartmouth and the University of Maine have collaborated to carry out research on Jarvis Glacier in Alaska, a geometrically simple, wet-based glacier. Here, we constructed and deployed an array of 25 tilt sensors into 3 boreholes drilled along the glacier's shear margin. Our goal is to obtain 3D strain measurements to calculate the full velocity field & create deformation regime maps in the vicinity of the boreholes, as well as to support numerical modeling. The tilt sensors were developed in-lab: Each tilt sensor comes equipped with an LSM303C chip (embedded with a 3-axis accelerometer and magnetometer) and Arduino Pro-Mini mounted on a custom-made printed circuit board encased within a watertight aluminum tube. The design concept was to produce a sensor string, consisting of tilt sensors spaced apart at pre-calculated intervals, to be lowered into a borehole and frozen-in over months to collect strain data through a Campbell Scientific CR1000 datalogger. Three surface-to-bed boreholes were successfully installed with tilt sensor strings. Given the lack of prior in-situ borehole geophysics studies on polythermal glaciers, deliberate consideration on factors such as strain relief and waterproofing electrical components was necessary in the development of the sensor system. On-site challenges also arose due

  11. Cardiovascular autonomic responses to head-up tilt in gestational hypertension and normal pregnancy.

    Science.gov (United States)

    Heiskanen, Nonna; Saarelainen, Heli; Kärkkäinen, Henna; Valtonen, Pirjo; Lyyra-Laitinen, Tiina; Laitinen, Tomi; Vanninen, Esko; Heinonen, Seppo

    2011-04-01

    The aim of the present study was to evaluate the influence of gestational hypertension on hemodynamics and cardiovascular autonomic regulation at rest and their responses to head-up tilt (HUT). We prospectively studied 56 pregnant women (28 with gestational hypertension and 28 healthy pregnant women) during the third trimester of pregnancy and 3 months after pregnancy. In women with pregnancy-induced hypertension, compared with control women, there were significant differences in hemodynamics and in markers of cardiovascular regulation (p Postural change from the supine to the upright position was associated with significant changes in hemodynamic responses in both groups during pregnancy (from p pregnancies (p changes in autonomic nervous function in hypertensive women appeared to be a feature of gestational-induced hypertension.

  12. A tilting approach to ranking influence

    KAUST Repository

    Genton, Marc G.

    2014-12-01

    We suggest a new approach, which is applicable for general statistics computed from random samples of univariate or vector-valued or functional data, to assessing the influence that individual data have on the value of a statistic, and to ranking the data in terms of that influence. Our method is based on, first, perturbing the value of the statistic by ‘tilting’, or reweighting, each data value, where the total amount of tilt is constrained to be the least possible, subject to achieving a given small perturbation of the statistic, and, then, taking the ranking of the influence of data values to be that which corresponds to ranking the changes in data weights. It is shown, both theoretically and numerically, that this ranking does not depend on the size of the perturbation, provided that the perturbation is sufficiently small. That simple result leads directly to an elegant geometric interpretation of the ranks; they are the ranks of the lengths of projections of the weights onto a ‘line’ determined by the first empirical principal component function in a generalized measure of covariance. To illustrate the generality of the method we introduce and explore it in the case of functional data, where (for example) it leads to generalized boxplots. The method has the advantage of providing an interpretable ranking that depends on the statistic under consideration. For example, the ranking of data, in terms of their influence on the value of a statistic, is different for a measure of location and for a measure of scale. This is as it should be; a ranking of data in terms of their influence should depend on the manner in which the data are used. Additionally, the ranking recognizes, rather than ignores, sign, and in particular can identify left- and right-hand ‘tails’ of the distribution of a random function or vector.

  13. Tilt rotor tricopter : control system for the holonomic multirotor platform

    OpenAIRE

    Gjertsen, Sindre; Salem, Daniel

    2013-01-01

    Masteroppgave i mekatronikk MAS500 2013 – Universitetet i Agder, Grimstad Development of a new approach to the multicopter segment of the Unmanned Areal Vehicle (UAV) family is presented. The system is designed on a T-shaped tricopter platform with ability to tilt all three motors, hereby defined as Tilt Rotor Tricopter (TRT). The highly coupled nonlinear system is investigated through the mathematical model, and verified by simulations. Linearization of the system has been ach...

  14. Clustering of resting state networks.

    Directory of Open Access Journals (Sweden)

    Megan H Lee

    Full Text Available The goal of the study was to demonstrate a hierarchical structure of resting state activity in the healthy brain using a data-driven clustering algorithm.The fuzzy-c-means clustering algorithm was applied to resting state fMRI data in cortical and subcortical gray matter from two groups acquired separately, one of 17 healthy individuals and the second of 21 healthy individuals. Different numbers of clusters and different starting conditions were used. A cluster dispersion measure determined the optimal numbers of clusters. An inner product metric provided a measure of similarity between different clusters. The two cluster result found the task-negative and task-positive systems. The cluster dispersion measure was minimized with seven and eleven clusters. Each of the clusters in the seven and eleven cluster result was associated with either the task-negative or task-positive system. Applying the algorithm to find seven clusters recovered previously described resting state networks, including the default mode network, frontoparietal control network, ventral and dorsal attention networks, somatomotor, visual, and language networks. The language and ventral attention networks had significant subcortical involvement. This parcellation was consistently found in a large majority of algorithm runs under different conditions and was robust to different methods of initialization.The clustering of resting state activity using different optimal numbers of clusters identified resting state networks comparable to previously obtained results. This work reinforces the observation that resting state networks are hierarchically organized.

  15. A new tilt on pelvic radiographs: a pilot study

    Energy Technology Data Exchange (ETDEWEB)

    Richards, P.J. [North Staffordshire Royal Infirmary, Department of Radiology, Stoke-on-Trent, Staffordshire (United Kingdom); Pattison, J.M. [University Hospital of North Staffordshire, Department of Radiology, Stoke on Trent (United Kingdom); Belcher, J. [Keele University, Department of Mathematics, Keele, Staffordshire (United Kingdom); DeCann, R.W. [IMECS, Department of Radiology, Market Drayton, Shropshire (United Kingdom); Anderson, Suzanne [University of Melbourne, Department of Radiology, Melbourne (Australia); Wynn-Jones, C. [University Hospital of North Staffordshire, Department of Orthopaedic Surgery, Stoke on Trent (United Kingdom)

    2009-02-15

    The aim of this study was to evaluate pelvic tilt on commonly performed measurements on radiography in primary protrusio acetabuli and developmental dysplasia of the hip. A dry assembled pelvis and spine skeleton was positioned in an isocentric skull unit and films exposed with increasing degrees of angulation of pelvic tilt. The films were then read by two independent readers for seven different measurements used to evaluate the hips and acetabular: acetabular line to ilioischial line, teardrop appearance, intercristal/intertuberous ratio, co-ordinates of femoral head, centre edge angle, acetabular depth/width ratio and acetabular angle. There was so much variation in the protrusio results that no formal recommendation of any standard radiographic test can be given. Only the inter tuberous distance is not effected by pelvic tilt. The acetabular angles for developmental dysplasia of the hip showed the most potential with pelvic tilt below 15 . As pelvic tilt increases, measurements used in protusio become unreliable, and computed tomography/magnetic resonance imaging are probably going to be more accurate as one can directly visualise pelvic intrusion. We recommend a lateral view to assess the degree of pelvic tilt in patients with protrusion to ensure these measurements are valid. (orig.)

  16. Optimal tilt-angles for solar collectors used in China

    International Nuclear Information System (INIS)

    Tang Runsheng; Wu Tong

    2004-01-01

    A reasonable estimation of the optimal tilt angle of a fixed collector for maximizing its energy collection must be done based on the monthly global and diffuse radiation on a horizontal surface. However, the monthly diffuse radiation is not always available in many places. In this paper, a simple mathematical procedure for the estimation of the optimal tilt angle of a collector is presented based on the monthly horizontal radiation. A comparison of the optimal tilt angles of collectors obtained from expected monthly diffuse radiation and that from the actual monthly diffuse radiation showed that this method gives a good estimation of the optimal tilt angle, except for places with a considerably lower clearness index. A contour map of the optimal tilt angle of the south-facing collectors used for the entire year in China is also outlined, based on monthly horizontal radiation of 152 places around the country, combing the optimal tilt angle of another 30 cities based on the actual monthly diffuse radiation

  17. Tilted hexagonal post arrays: DNA electrophoresis in anisotropic media.

    Science.gov (United States)

    Chen, Zhen; Dorfman, Kevin D

    2014-02-01

    Using Brownian dynamics simulations, we show that DNA electrophoresis in a hexagonal array of micron-sized posts changes qualitatively when the applied electric field vector is not coincident with the lattice vectors of the array. DNA electrophoresis in such "tilted" post arrays is superior to the standard "un-tilted" approach; while the time required to achieve a resolution of unity in a tilted post array is similar to an un-tilted array at a low-electric field strengths, this time (i) decreases exponentially with electric field strength in a tilted array and (ii) increases exponentially with electric field strength in an un-tilted array. Although the DNA dynamics in a post array are complicated, the electrophoretic mobility results indicate that the "free path," i.e. the average distance of ballistic trajectories of point-sized particles launched from random positions in the unit cell until they intersect the next post, is a useful proxy for the detailed DNA trajectories. The analysis of the free path reveals a fundamental connection between anisotropy of the medium and DNA transport therein that goes beyond simply improving the separation device. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Age, splanchnic vasoconstriction, and heat stress during tilting

    Science.gov (United States)

    Minson, C. T.; Wladkowski, S. L.; Pawelczyk, J. A.; Kenney, W. L.

    1999-01-01

    During upright tilting, blood is translocated to the dependent veins of the legs and compensatory circulatory adjustments are necessary to maintain arterial pressure. For examination of the effect of age on these responses, seven young (23 +/- 1 yr) and seven older (70 +/- 3 yr) men were head-up tilted to 60 degrees in a thermoneutral condition and during passive heating with water-perfused suits. Measurements included heart rate (HR), cardiac output (Qc; acetylene rebreathing technique), central venous pressure (CVP), blood pressures, forearm blood flow (venous occlusion plethysmography), splanchnic and renal blood flows (indocyanine green and p-aminohippurate clearance), and esophageal and mean skin temperatures. In response to tilting in the thermoneutral condition, CVP and stroke volume decreased to a greater extent in the young men, but HR increased more, such that the fall in Qc was similar between the two groups in the upright posture. The rise in splanchnic vascular resistance (SVR) was greater in the older men, but the young men increased forearm vascular resistance (FVR) to a greater extent than the older men. The fall in Qc during combined heat stress and tilting was greater in the young compared with older men. Only four of the young men versus six of the older men were able to finish the second tilt without becoming presyncopal. In summary, the older men relied on a greater increase in SVR to compensate for a reduced ability to constrict the skin and muscle circulations (as determined by changes in FVR) during head-up tilting.

  19. Pebble-bed reactor

    International Nuclear Information System (INIS)

    Lohnert, G.; Mueller-Frank, U.; Heil, J.

    1976-01-01

    A pebble-bed nuclear reactor of large power rating comprises a container having a funnel-shaped bottom forming a pebble run-out having a centrally positioned outlet. A bed of downwardly-flowing substantially spherical nuclear fuel pebbles is positioned in the container and forms a reactive nuclear core maintained by feeding unused pebbles to the bed's top surface while used or burned-out pebbles run out and discharge through the outlet. A substantially conical body with its apex pointing upwardly and its periphery spaced from the periphery of the container spreads the bottom of the bed outwardly to provide an annular flow down the funnel-shaped bottom forming the runout, to the discharge outlet. This provides a largely constant downward velocity of the spheres throughout the diameter of the bed throughout a substantial portion of the down travel, so that all spheres reach about the same burned-out condition when they leave the core, after a single pass through the core area

  20. Fluidised bed heat exchangers

    International Nuclear Information System (INIS)

    Elliott, D.E.; Healey, E.M.; Roberts, A.G.

    1974-01-01

    Problems that have arisen during the initial stages of development of fluidised bed boilers in which heat transfer surfaces are immersed in fluidised solids are discussed. The very high heat transfer coefficients that are obtained under these conditions can be exploited to reduce the total heat transfer surface to a fraction of that in normal boilers. However, with the high heat flux levels involved, tube stressing becomes more important and it is advantageous to use smaller diameter tubes. One of the initial problems was that the pumping power absorbed by the fluidised bed appeared to be high. The relative influence of the fluidising velocity (and the corresponding bed area), tube diameter, tube spacing, heat transfer coefficient and bed temperature on pumping power and overall cost was determined. This showed the importance of close tube packing and research was undertaken to see if this would adversely affect the heat transfer coefficient. Pressure operation also reduces the pumping power. Fouling and corrosion tests in beds burning coal suggest that higher temperatures could be reached reliably and cost studies show that, provided the better refractory metals are used, the cost of achieving higher temperatures is not unduly high. It now remains to demonstrate at large scale that the proposed systems are viable and that the methods incorporated to overcome start up and part lead running problems are satisfactory. The promising role of these heat transfer techniques in other applications is briefly discussed

  1. Magnetic configurations of the tilted current sheets in magnetotail

    Directory of Open Access Journals (Sweden)

    C. Shen

    2008-11-01

    Full Text Available In this research, the geometrical structures of tilted current sheet and tail flapping waves have been analysed based on multiple spacecraft measurements and some features of the tilted current sheets have been made clear for the first time. The geometrical features of the tilted current sheet revealed in this investigation are as follows: (1 The magnetic field lines (MFLs in the tilted current sheet are generally plane curves and the osculating planes in which the MFLs lie are about vertical to the equatorial plane, while the normal of the tilted current sheet leans severely to the dawn or dusk side. (2 The tilted current sheet may become very thin, the half thickness of its neutral sheet is generally much less than the minimum radius of the curvature of the MFLs. (3 In the neutral sheet, the field-aligned current density becomes very large and has a maximum value at the center of the current sheet. (4 In some cases, the current density is a bifurcated one, and the two humps of the current density often superpose two peaks in the gradient of magnetic strength, indicating that the magnetic gradient drift current is possibly responsible for the formation of the two humps of the current density in some tilted current sheets. Tilted current sheets often appear along with tail current sheet flapping waves. It is found that, in the tail flapping current sheets, the minimum curvature radius of the MFLs in the current sheet is rather large with values around 1 RE, while the neutral sheet may be very thin, with its half thickness being several tenths of RE. During the flapping waves, the current sheet is tilted substantially, and the maximum tilt angle is generally larger than 45°. The phase velocities of these flapping waves are several tens km/s, while their periods and wavelengths are several tens of minutes, and several earth radii, respectively. These tail flapping events generally last several hours and occur during quiet periods or periods of

  2. Preferences of Freestall Housed Dairy Cows to Different Bedding Materials

    OpenAIRE

    MITEV, Jurii; VARLYAKOV, Ivan; MITEVA, Tchonka; VASILEV, Nasko; GERGOVSKA, Jivka; UZUNOVA, Krassimira; DIMOVA, Vania

    2012-01-01

    ABSTRACT The purpose of this study was to examine the behaviour of dairy cows during the rest periods and their preferences to different bedding materials with limited amount of straw as well as the hygienic score of dairy cows. Thirty-six Holstein dairy cows at the first to fourth lactation with live weight 610±58 kg and milk yield of 7364±1202 liter for 305 days of lactation were used for the experiment. Three types of bedding materials were used for the preference tes...

  3. Efficacy of tilt training in patients with vasovagal syncope.

    Science.gov (United States)

    Gajek, Jacek; Zyśko, Dorota; Mazurek, Walentyna

    2006-06-01

    Besides pharmacological therapy and pacemaker implantation, tilt training is a promising method of treatment in patients with vasovagal syncope (VVS). Tilt training is usually offered to patients with malignant or recurrent VVS which impairs their quality of life and carries a risk of injury. To assess the efficacy of tilt training in patients with VVS. The study group consisted of 40 patients (29 females, 11 males, aged 36.6+/-14 years, range 18-57 years) who underwent tilt training using tilt table testing according to the Westminster protocol. The mean number of syncopal episodes prior to the initiation of tilt training was 6.5+/-4.9 (range 0-20); 3 patients had a history of very frequent faints. According to the VASIS classification, type I VVS (mixed) was diagnosed in 17 patients, type II (cardioinhibitory) in 22 subjects, and type III (vasodepressive) in one patient. Mean follow-up duration was 35.1+/-13.5 months. The control group, which did not undergo the tilt testing programme, consisted of 29 patients with VVS (25 females, 4 males, mean age 44.2+/-15.0 years) who had a mean of 3.3+/-3.2 (range 0-12) syncopal episodes in the past (p <0.05 vs study group); 6 of these patients had only pre-syncopal episodes. Type I VVS was diagnosed in 23 controls and type II VVS in 6 control subjects (syncope occurred during the passive phase of tilt testing in 7 subjects, whereas the remaining 22 fainted during NTG infusion). Of the patients from the study group, 3 underwent pacemaker implantation at the time of the initiation of tilt training. At the end of follow-up, 31 (77.5%) patients remained free from syncope recurrences, 5 had syncopal episodes during the initial phase of tilt training, whereas the remaining 4 continued to suffer from syncopal episodes. Out of 3 patients with presyncope, 2 had no syncope recurrences whereas 1 patient continued to have presyncopal attacks. Out of 3 patients with pacemakers, 1 reported activation of pacing in the interventional mode

  4. in Spouted Bed

    Directory of Open Access Journals (Sweden)

    Bronislaw Buczek

    2013-01-01

    Full Text Available Samples of active coke, fresh and spent after cleaning flue gases from communal waste incinerators, were investigated. The outer layers of both coke particles were separately removed by comminution in a spouted bed. The samples of both active cokes were analysed by means of densities, mercury porosimetry, and adsorption technique. Remaining cores were examined to determine the degree of consumption of coke by the sorption of hazardous emissions (SO2, HCl, and heavy metals through its bed. Differences in contamination levels within the porous structure of the particles were estimated. The study demonstrated the effectiveness of commercial active coke in the cleaning of flue gases.

  5. The Safety of Hospital Beds

    Science.gov (United States)

    Gervais, Pierre; Pooler, Charlotte; Merryweather, Andrew; Doig, Alexa K.; Bloswick, Donald

    2015-01-01

    To explore the safety of the standard and the low hospital bed, we report on a microanalysis of 15 patients’ ability to ingress, move about the bed, and egress. The 15 participants were purposefully selected with various disabilities. Bed conditions were randomized with side rails up or down and one low bed with side rails down. We explored the patients’ use of the side rails, bed height, ability to lift their legs onto the mattress, and ability to turn, egress, and walk back to the chair. The standard bed was too high for some participants, both for ingress and egress. Side rails were used by most participants when entering, turning in bed, and exiting. We recommend that side rails be reconsidered as a means to facilitate in-bed movement, ingress, and egress. Furthermore, single deck height settings for all patients are not optimal. Low beds as a safety measure must be re-evaluated. PMID:28462302

  6. Group theoretical analysis of octahedral tilting in perovskites

    International Nuclear Information System (INIS)

    Howard, C.J.; Stokes, H.T.

    1998-01-01

    Full text: Structures of the perovskite family, ABX 3 , have interested crystallographers over many years, and continue to attract attention on account of their fascinating electrical and magnetic properties, for example the giant magnetoresistive effects exhibited by certain perovskite materials. The ideal perovskite (cubic, space group Pm -/3 m) is a particularly simple structure, but also a demanding one, since aside from the lattice parameter there are no variable parameters in the structure. Consequently, the majority of perovskite structures are distorted perovskites (hettotypes), the most common distortion being the corner-linked tilting of the practically rigid BX 6 octahedral units. In this work, group theoretical methods have been applied to the study of octahedral tilting in perovskites. The only irreducible representations of the parent group (Pm -/3 m) which produce octahedral tilting subject to corner-linking constraints are M + / 3 and R 4 ' + . A six-dimensional order parameter in the reducible representation space of M + / 3 + R + / 4 describes the different possible tilting patterns. The space groups for the different perovskites are then simply the isotropy subgroups, comprising those operations which leave the order parameter invariant. The isotropy subgroups are obtained from a computer program or tabulations. The analysis yields a list of fifteen possible space groups for perovskites derived through octahedral tilting. A connection is made to the (twenty-three) tilt systems given previously by Glazer. The group-subgroup relationships have been derived and displayed. It is interesting to note that all known perovskites based on octahedral tilting conform with the fifteen space groups on our list, with the exception of one perovskite at high temperature, the structure of which seems poorly determined

  7. Influence of Vibrotactile Feedback on Controlling Tilt Motion After Spaceflight

    Science.gov (United States)

    Wood, S. J.; Rupert, A. H.; Vanya, R. D.; Esteves, J. T.; Clement, G.

    2011-01-01

    We hypothesize that adaptive changes in how inertial cues from the vestibular system are integrated with other sensory information leads to perceptual disturbances and impaired manual control following transitions between gravity environments. The primary goals of this ongoing post-flight investigation are to quantify decrements in manual control of tilt motion following short-duration spaceflight and to evaluate vibrotactile feedback of tilt as a sensorimotor countermeasure. METHODS. Data is currently being collected on 9 astronaut subjects during 3 preflight sessions and during the first 8 days after Shuttle landings. Variable radius centrifugation (216 deg/s, body axis, thereby eliciting canal reflexes without concordant otolith or visual cues. A simple 4 tactor system was implemented to provide feedback when tilt position exceeded predetermined levels in either device. Closed-loop nulling tasks are performed during random tilt steps or sum-of-sines (TTS only) with and without vibrotactile feedback of chair position. RESULTS. On landing day the manual control performance without vibrotactile feedback was reduced by >30% based on the gain or the amount of tilt disturbance successfully nulled. Manual control performance tended to return to baseline levels within 1-2 days following landing. Root-mean-square position error and tilt velocity were significantly reduced with vibrotactile feedback. CONCLUSIONS. These preliminary results are consistent with our hypothesis that adaptive changes in vestibular processing corresponds to reduced manual control performance following G-transitions. A simple vibrotactile prosthesis improves the ability to null out tilt motion within a limited range of motion disturbances.

  8. Rules and mechanisms governing octahedral tilts in perovskites under pressure

    Science.gov (United States)

    Xiang, H. J.; Guennou, Mael; Íñiguez, Jorge; Kreisel, Jens; Bellaiche, L.

    2017-08-01

    The rotation of octahedra (octahedral tilting) is common in A B O3 perovskites and relevant to many physical phenomena, ranging from electronic and magnetic properties, metal-insulator transitions to improper ferroelectricity. Hydrostatic pressure is an efficient way to tune and control octahedral tiltings. However, the pressure behavior of such tiltings can dramatically differ from one material to another, with the origins of such differences remaining controversial. In this paper, we discover several new mechanisms and formulate a set of simple rules that allow us to understand how pressure affects oxygen octahedral tiltings via the use and analysis of first-principles results for a variety of compounds. Besides the known A -O interactions, we reveal that the interactions between specific B ions and oxygen ions contribute to the tilting instability. We explain the previously reported trend that the derivative of the oxygen octahedral tilting with respect to pressure (dR /dP ) usually decreases with both the tolerance factor and the ionization state of the A ion by illustrating the key role of A -O interactions and their change under pressure. Furthermore, three new mechanisms/rules are discovered, namely that (i) the octahedral rotations in A B O3 perovskites with empty low-lying d states on the B site are greatly enhanced by pressure, in order to lower the electronic kinetic energy; (ii) dR /dP is enhanced when the system possesses weak tilt instabilities, and (iii) for the most common phase exhibited by perovskites—the orthorhombic Pbnm state—the in-phase and antiphase octahedral rotations are not automatically both suppressed or both enhanced by the application of pressure because of a trilinear coupling between these two rotation types and an antipolar mode involving the A ions. We further predict that the polarization associated with the so-called hybrid improper ferroelectricity could be manipulated by hydrostatic pressure by indirectly controlling the

  9. Retinal Nerve Fiber Layer Protrusion Associated with Tilted Optic Discs.

    Science.gov (United States)

    Chiang, Jaclyn; Yapp, Michael; Ly, Angelica; Hennessy, Michael P; Kalloniatis, Michael; Zangerl, Barbara

    2018-03-01

    This study resulted in the identification of an optic nerve head (ONH) feature associated with tilted optic discs, which might potentially contribute to ONH pathologies. Knowledge of such findings will enhance clinical insights and drive future opportunities to understand disease processes related to tilted optic discs. The aim of this study was to identify novel retinal nerve fiber layer (RNFL) anomalies by evaluating tilted optic discs using optical coherence tomography. An observed retinal nerve fiber protrusion was further investigated for association with other morphological or functional parameters. A retrospective review of 400 randomly selected adult patients with ONH examinations was conducted in a referral-only, diagnostic imaging center. After excluding other ONH pathologies, 215 patients were enrolled and evaluated for optic disc tilt and/or torsion. Gross anatomical ONH features, including size and rim or parapapillary region elevation, were assessed with stereoscopic fundus photography. Optical coherence tomography provided detailed morphological information of individual retinal layers. Statistical analysis was applied to identify significant changes between individual patient cohorts. A dome-shaped hyperreflective RNFL bulge, protruding into the neurosensory retina at the optic disc margins, was identified in 17 eyes with tilted optic discs. Available follow-up data were inconclusive regarding natural changes with this ONH feature. This RNFL herniation was significantly correlated with smaller than average optic disc size (P = .005), congenital disc tilt (P optic discs, which has not previously been assessed as an independent ONH structure. The feature is predominantly related to congenital crowded, small optic discs and variable between patients. This study is an important first step to elucidate diagnostic capabilities of tilted disc morphological changes and understanding associated functional deficits.

  10. Apparatus for controlling fluidized beds

    Science.gov (United States)

    Rehmat, A.G.; Patel, J.G.

    1987-05-12

    An apparatus and process are disclosed for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance. 2 figs.

  11. Skin cooling maintains cerebral blood flow velocity and orthostatic tolerance during tilting in heated humans

    Science.gov (United States)

    Wilson, Thad E.; Cui, Jian; Zhang, Rong; Witkowski, Sarah; Crandall, Craig G.

    2002-01-01

    Orthostatic tolerance is reduced in the heat-stressed human. The purpose of this project was to identify whether skin-surface cooling improves orthostatic tolerance. Nine subjects were exposed to 10 min of 60 degrees head-up tilting in each of four conditions: normothermia (NT-tilt), heat stress (HT-tilt), normothermia plus skin-surface cooling 1 min before and throughout tilting (NT-tilt(cool)), and heat stress plus skin-surface cooling 1 min before and throughout tilting (HT-tilt(cool)). Heating and cooling were accomplished by perfusing 46 and 15 degrees C water, respectively, though a tube-lined suit worn by each subject. During HT-tilt, four of nine subjects developed presyncopal symptoms resulting in the termination of the tilt test. In contrast, no subject experienced presyncopal symptoms during NT-tilt, NT-tilt(cool), or HT-tilt(cool). During the HT-tilt procedure, mean arterial blood pressure (MAP) and cerebral blood flow velocity (CBFV) decreased. However, during HT-tilt(cool), MAP, total peripheral resistance, and CBFV were significantly greater relative to HT-tilt (all P heat-stressed humans.

  12. Fluidized bed calciner

    International Nuclear Information System (INIS)

    Sheely, W.F.

    1986-01-01

    A unique way to convert radioactive scrap into useful nuclear fuel products was developed for the Department of Energy at Hanford. An advanced, fluidized bed calciner is used to convert metallic nitrate scrap or waste solutions into benign, solid and gaseous products. There are broad potential applications of this concept beyond those in the nuclear industry

  13. Nail Bed Injuries

    Science.gov (United States)

    ... All Topics A-Z Videos Infographics Symptom Picker Anatomy Bones Joints Muscles Nerves Vessels Tendons About Hand Surgery What is a Hand Surgeon? What is a Hand Therapist? Media Find a Hand Surgeon Home Anatomy Nail Bed Injuries Email to a friend * required ...

  14. Bed Bug Myths

    Science.gov (United States)

    Learn the truth about bed bugs, such as how easy they are to see with the naked eye, their preferred habitat, whether they transmit diseases, their public health effects, and whether pesticides are the best way to deal with an infestation.

  15. RESTful Java web services security

    CERN Document Server

    Enríquez, René

    2014-01-01

    A sequential and easy-to-follow guide which allows you to understand the concepts related to securing web apps/services quickly and efficiently, since each topic is explained and described with the help of an example and in a step-by-step manner, helping you to easily implement the examples in your own projects. This book is intended for web application developers who use RESTful web services to power their websites. Prior knowledge of RESTful is not mandatory, but would be advisable.

  16. Rotating Shaft Tilt Angle Measurement Using an Inclinometer

    Science.gov (United States)

    Luo, Jun; Wang, Zhiqian; Shen, Chengwu; Wen, Zhuoman; Liu, Shaojin; Cai, Sheng; Li, Jianrong

    2015-10-01

    This paper describes a novel measurement method to accurately measure the rotating shaft tilt angle of rotating machine for alignment or compensation using a dual-axis inclinometer. A model of the rotating shaft tilt angle measurement is established using a dual-axis inclinometer based on the designed mechanical structure, and the calculation equation between the rotating shaft tilt angle and the inclinometer axes outputs is derived under the condition that the inclinometer axes are perpendicular to the rotating shaft. The reversal measurement method is applied to decrease the effect of inclinometer drifts caused by temperature, to eliminate inclinometer and rotating shaft mechanical error and inclinometer systematic error to attain high measurement accuracy. The uncertainty estimation shows that the accuracy of rotating shaft tilt angle measurement depends mainly on the inclinometer uncertainty and its uncertainty is almost the same as the inclinometer uncertainty in the simulation. The experimental results indicate that measurement time is 4 seconds; the range of rotating shaft tilt angle is 0.002° and its standard deviation is 0.0006° using NS-5/P2 inclinometer, whose precision and resolution are ±0.01° and 0.0005°, respectively.

  17. Rotating Shaft Tilt Angle Measurement Using an Inclinometer

    Directory of Open Access Journals (Sweden)

    Luo Jun

    2015-10-01

    Full Text Available This paper describes a novel measurement method to accurately measure the rotating shaft tilt angle of rotating machine for alignment or compensation using a dual-axis inclinometer. A model of the rotating shaft tilt angle measurement is established using a dual-axis inclinometer based on the designed mechanical structure, and the calculation equation between the rotating shaft tilt angle and the inclinometer axes outputs is derived under the condition that the inclinometer axes are perpendicular to the rotating shaft. The reversal measurement method is applied to decrease the effect of inclinometer drifts caused by temperature, to eliminate inclinometer and rotating shaft mechanical error and inclinometer systematic error to attain high measurement accuracy. The uncertainty estimation shows that the accuracy of rotating shaft tilt angle measurement depends mainly on the inclinometer uncertainty and its uncertainty is almost the same as the inclinometer uncertainty in the simulation. The experimental results indicate that measurement time is 4 seconds; the range of rotating shaft tilt angle is 0.002° and its standard deviation is 0.0006° using NS-5/P2 inclinometer, whose precision and resolution are ±0.01° and 0.0005°, respectively.

  18. Modulated electron bunch with amplitude front tilt in an undulator

    International Nuclear Information System (INIS)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2015-12-01

    In a previous paper we discussed the physics of a microbunched electron beam kicked by the dipole field of a corrector magnet by describing the kinematics of coherent undulator radiation after the kick. We demonstrated that the effect of aberration of light supplies the basis for understanding phenomena like the deflection of coherent undulator radiation by a dipole magnet. We illustrated this fact by examining the operation of an XFEL under the steady state assumption, that is a harmonic time dependence. We argued that in this particular case the microbunch front tilt has no objective meaning; in other words, there is no experiment that can discriminate whether an electron beam is endowed with a microbunch front tilt of not. In this paper we extend our considerations to time-dependent phenomena related with a finite electron bunch duration, or SASE mode of operation. We focus our attention on the spatiotemporal distortions of an X-ray pulse. Spatiotemporal coupling arises naturally in coherent undulator radiation behind the kick, because the deflection process involves the introduction of a tilt of the bunch profile. This tilt of the bunch profile leads to radiation pulse front tilt, which is equivalent to angular dispersion of the output radiation. We remark that our exact results can potentially be useful to developers of new generation XFEL codes for cross-checking their results.

  19. Quantization of band tilting in modulated phononic crystals

    Science.gov (United States)

    Nassar, H.; Chen, H.; Norris, A. N.; Huang, G. L.

    2018-01-01

    A general theory of the tilting of dispersion bands in phononic crystals whose properties are being slowly and periodically modulated in space and time is established. The ratio of tilt to modulation speed is calculated, for the first time, in terms of Berry's phase and curvature and is proven to be a robust integer-valued Chern number. Derivations are based on a version of the adiabatic theorem for elastic waves demonstrated thanks to WKB asymptotics. Findings are exemplified in the case of a 3-periodic discrete spring-mass lattice. Tilted dispersion diagrams plotted using fully numerical simulations and semianalytical calculations based on a numerically gauge invariant expression of Berry's phase show perfect agreement. One-way blocking of waves due to the tilt, and ultimately to the breaking of reciprocity, is illustrated numerically and shown to be highly significant across a limited number of unit cells, suggesting the feasibility of experimental demonstrations. Finally, a version of the bulk-edge correspondence principle relating the tilt of bulk bands to the number of one-way gapless edge states is demonstrated.

  20. 7 CFR 2902.15 - Bedding, bed linens, and towels.

    Science.gov (United States)

    2010-01-01

    ... PROCUREMENT Designated Items § 2902.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that... minimum biobased content is 12 percent and shall be based on the amount of qualifying biobased carbon in..., and silk are not qualifying biobased feedstocks for the purpose of determining the biobased content of...

  1. How do visual and postural cues combine for self-tilt perception during slow pitch rotations?

    Science.gov (United States)

    Scotto Di Cesare, C; Buloup, F; Mestre, D R; Bringoux, L

    2014-11-01

    Self-orientation perception relies on the integration of multiple sensory inputs which convey spatially-related visual and postural cues. In the present study, an experimental set-up was used to tilt the body and/or the visual scene to investigate how these postural and visual cues are integrated for self-tilt perception (the subjective sensation of being tilted). Participants were required to repeatedly rate a confidence level for self-tilt perception during slow (0.05°·s(-1)) body and/or visual scene pitch tilts up to 19° relative to vertical. Concurrently, subjects also had to perform arm reaching movements toward a body-fixed target at certain specific angles of tilt. While performance of a concurrent motor task did not influence the main perceptual task, self-tilt detection did vary according to the visuo-postural stimuli. Slow forward or backward tilts of the visual scene alone did not induce a marked sensation of self-tilt contrary to actual body tilt. However, combined body and visual scene tilt influenced self-tilt perception more strongly, although this effect was dependent on the direction of visual scene tilt: only a forward visual scene tilt combined with a forward body tilt facilitated self-tilt detection. In such a case, visual scene tilt did not seem to induce vection but rather may have produced a deviation of the perceived orientation of the longitudinal body axis in the forward direction, which may have lowered the self-tilt detection threshold during actual forward body tilt. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. VA National Bed Control System

    Data.gov (United States)

    Department of Veterans Affairs — The VA National Bed Control System records the levels of operating, unavailable and authorized beds at each VAMC, and it tracks requests for changes in these levels....

  3. Getting Rid of Bed Bugs

    Science.gov (United States)

    ... Directory Planning, Budget and Results Jobs and Internships Headquarters Offices Regional Offices Labs and Research Centers Bed ... to be careful in how you select a company. Related Information Collaborative Strategy on Bed Bugs - highlights ...

  4. Quantum well electronic states in a tilted magnetic field.

    Science.gov (United States)

    Trallero-Giner, C; Padilha, J X; Lopez-Richard, V; Marques, G E; Castelano, L K

    2017-08-16

    We report the energy spectrum and the eigenstates of conduction and uncoupled valence bands of a quantum well under the influence of a tilted magnetic field. In the framework of the envelope approximation, we implement two analytical approaches to obtain the nontrivial solutions of the tilted magnetic field: (a) the Bubnov-Galerkin spectral method and b) the perturbation theory. We discuss the validity of each method for a broad range of magnetic field intensity and orientation as well as quantum well thickness. By estimating the accuracy of the perturbation method, we provide explicit analytical solutions for quantum wells in a tilted magnetic field configuration that can be employed to study several quantitative phenomena.

  5. Method to fabricate a tilted logpile photonic crystal

    Science.gov (United States)

    Williams, John D.; Sweatt, William C.

    2010-10-26

    A method to fabricate a tilted logpile photonic crystal requires only two lithographic exposures and does not require mask repositioning between exposures. The mask and photoresist-coated substrate are spaced a fixed and constant distance apart using a spacer and the stack is clamped together. The stack is then tilted at a crystallographic symmetry angle (e.g., 45 degrees) relative to the X-ray beam and rotated about the surface normal until the mask is aligned with the X-ray beam. The stack is then rotated in plane by a small stitching angle and exposed to the X-ray beam to pattern the first half of the structure. The stack is then rotated by 180.degree. about the normal and a second exposure patterns the remaining half of the structure. The method can use commercially available DXRL scanner technology and LIGA processes to fabricate large-area, high-quality tilted logpile photonic crystals.

  6. Tilt Precursors before Earthquakes on the San Andreas Fault, California.

    Science.gov (United States)

    Johnston, M J; Mortensen, C E

    1974-12-13

    An array of 14 biaxial shallow-borehole tiltmeters (at 1O(-7) radian sensitivity) has been installed along 85 kilometers of the San Andreas fault during the past year. Earthquake-related changes in tilt have been simultaneously observed on up to four independent instruments. At earthquake distances greater than 10 earthquake source dimensions, there are few clear indications of tilt change. For the four instruments with the longest records (> 10 months), 26 earthquakes have occurred since July 1973 with at least one instrument closer than 10 source dimensions and 8 earthquakes with more than one instrument within that distance. Precursors in tilt direction have been observed before more than 10 earthquakes or groups of earthquakes, and no similar effect has yet been seen without the occurrence of an earthquake.

  7. Robust tilt and lock mechanism for hopping actuator

    Energy Technology Data Exchange (ETDEWEB)

    Salton, Jonathan R.; Buerger, Stephen; Dullea, Kevin J.; Marron, Lisa C.; Salisbury, Curt Michael; Spletzer, Barry Louis

    2017-02-07

    A tilt and lock apparatus that includes a tilt servomechanism, a spiral torsion spring, a lock wheel, and a lock hook is described herein. The spiral torsion spring is mechanically coupled to the tilt servomechanism and the lock wheel (which includes an opening). When a shaft is positioned through the opening, rotation of the lock wheel is in unison with rotation of the shaft. An external surface of the lock wheel includes one or more grooves. The lock hook includes a head that engages and disengages the grooves. The lock wheel is stationary when the head engages one of the grooves and is rotatable when the head disengages the grooves. The head and the grooves are geometrically aligned when engaged to prevent creation of a force that acts to disengage the head responsive to an applied force acting on the shaft.

  8. NEuclid: a long-range tilt-immune homodyne interferometer

    Science.gov (United States)

    Bradshaw, M. J.; Speake, C. C.

    2017-11-01

    The new Easy to Use Compact Laser Interferometric Device (nEUCLID) is a polarisation-based homodyne interferometer with substantially unequal arms that is tolerant to target mirror tilt. The design has no active components, uses standard optical components of 25 mm diameter, has a working distance of 706 mm and a reference arm-length of 21 mm. nEUCLID optics have a footprint of 210 x 190 x 180 mm, and has a tolerance to target mirror tilt of +/- 0.5 degrees, made possible by a novel new retro-reflector design [1]. nEUCLID was built to a set of specifications laid down by Airbus Defence and Space, who required a lowmass, low-power device to measure displacement with nanometre accuracy for space applications. At the University of Birmingham we have previously built a smaller, more compact tilt-insensitive homodyne interferometer - the EUCLID [2, 3, 4] - which has a working distance of 6 mm, a working range of +/- 3 mm, and a tilt range of +/- 1° [2]. We created a new optical design to allow a much larger working distance to be achieved (as discussed in Section II) and used this in a new interferometer - the nEUCLID. Section II describes the interferometer in detail; how nEUCLID is tilt insensitive, and the optical configuration. Section III states the design specifications from Airbus Defence and Space and the components used in the final design. The output interference pattern from nEUCLID, and how it has been corrected with a meniscus lens, is also discussed. In Section IV we discuss the results demonstrating the tilt immunity range, and the sensitivity of the device. Section V describes several potential applications of nEUCLID, and Section VI draws together our conclusions.

  9. Radiographic cup anteversion measurement corrected from pelvic tilt.

    Science.gov (United States)

    Wang, Liao; Thoreson, Andrew R; Trousdale, Robert T; Morrey, Bernard F; Dai, Kerong; An, Kai-Nan

    2017-11-01

    The purpose of this study was to develop a novel technique to improve the accuracy of radiographic cup anteversion measurement by correcting the influence of pelvic tilt. Ninety virtual total hip arthroplasties were simulated from computed tomography data of 6 patients with 15 predetermined cup orientations. For each simulated implantation, anteroposterior (AP) virtual pelvic radiographs were generated for 11 predetermined pelvic tilts. A linear regression model was created to capture the relationship between radiographic cup anteversion angle error measured on AP pelvic radiographs and pelvic tilt. Overall, nine hundred and ninety virtual AP pelvic radiographs were measured, and 90 linear regression models were created. Pearson's correlation analyses confirmed a strong correlation between the errors of conventional radiographic cup anteversion angle measured on AP pelvic radiographs and the magnitude of pelvic tilt (P cup anteversion angle from the influence of pelvic tilt. The current method proposes to measure the pelvic tilt on a lateral radiograph, and to use it as a correction for the radiographic cup anteversion measurement on an AP pelvic radiograph. Thus, both AP and lateral pelvic radiographs are required for the measurement of pelvic posture-integrated cup anteversion. Compared with conventional radiographic cup anteversion, the errors of pelvic posture-integrated radiographic cup anteversion were reduced from 10.03 (SD = 5.13) degrees to 2.53 (SD = 1.33) degrees. Pelvic posture-integrated cup anteversion measurement improves the accuracy of radiographic cup anteversion measurement, which shows the potential of further clarifying the etiology of postoperative instability based on planar radiographs. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  10. Tilted dipole model for bias-dependent photoluminescence pattern

    Energy Technology Data Exchange (ETDEWEB)

    Fujieda, Ichiro, E-mail: fujieda@se.ritsumei.ac.jp; Suzuki, Daisuke; Masuda, Taishi [Department of Electrical and Electronic Engineering, Ritsumeikan University, Kusatsu 525-8577 (Japan)

    2014-12-14

    In a guest-host system containing elongated dyes and a nematic liquid crystal, both molecules are aligned to each other. An external bias tilts these molecules and the radiation pattern of the system is altered. A model is proposed to describe this bias-dependent photoluminescence patterns. It divides the liquid crystal/dye layer into sub-layers that contain electric dipoles with specific tilt angles. Each sub-layer emits linearly polarized light. Its radiation pattern is toroidal and is determined by the tilt angle. Its intensity is assumed to be proportional to the power of excitation light absorbed by the sub-layer. This is calculated by the Lambert-Beer's Law. The absorption coefficient is assumed to be proportional to the cross-section of the tilted dipole moment, in analogy to the ellipsoid of refractive index, to evaluate the cross-section for each polarized component of the excitation light. Contributions from all the sub-layers are added to give a final expression for the radiation pattern. Self-absorption is neglected. The model is simplified by reducing the number of sub-layers. Analytical expressions are derived for a simple case that consists of a single layer with tilted dipoles sandwiched by two layers with horizontally-aligned dipoles. All the parameters except for the tilt angle can be determined by measuring transmittance of the excitation light. The model roughly reproduces the bias-dependent photoluminescence patterns of a cell containing 0.5 wt. % coumarin 6. It breaks down at large emission angles. Measured spectral changes suggest that the discrepancy is due to self-absorption and re-emission.

  11. Tilt table standing for reducing spasticity after spinal cord injury.

    Science.gov (United States)

    Bohannon, R W

    1993-10-01

    A patient with a T12 spinal cord injury and intractable extensor spasms of the lower extremities participated in tilt table standing trial on 5 nonconsecutive days to determine if the intervention would affect his spasticity and spasms. Each day's standing trial was followed by an immediate reduction in lower extremity spasticity (measured using the modified Ashworth scale and pendulum testing). Standing was also accompanied by a reduction in spasms that lasted until the following morning. The reduction of spasms was particularly advantageous to the performance of car transfers. Tilt table standing merits further examination as a physical treatment of spasms that accompany central nervous system lesions.

  12. Flow tilt angles near forest edges - Part 1: Sonic anemometry

    DEFF Research Database (Denmark)

    Dellwik, Ebba; Mann, Jakob; Larsen, Klaus Steenberg

    2010-01-01

    distortion and vertical alignment, it was only possible to a limited extent to relate sonic anemometer flow tilt angles to upwind forest edges, but the results by the lidar indicated that an internal boundary layer affect flow tilt angles at 21m above the forest. This is in accordance with earlier studies......-flow angles were assumed for neutral flow, the data was interpreted in relation to upstream and downstream forest edges. Uncertainties caused by flow distortion, vertical misalignment and limited sampling time (statistical uncertainty) were evaluated and found to be highly significant. Since the attack angle...... balance, unless all terms in the carbon dioxide conservation equation can be precisely estimated....

  13. Sedimentary basins reconnaissance using the magnetic Tilt-Depth method

    Science.gov (United States)

    Salem, A.; Williams, S.; Samson, E.; Fairhead, D.; Ravat, D.; Blakely, R.J.

    2010-01-01

    We compute the depth to the top of magnetic basement using the Tilt-Depth method from the best available magnetic anomaly grids covering the continental USA and Australia. For the USA, the Tilt-Depth estimates were compared with sediment thicknesses based on drilling data and show a correlation of 0.86 between the datasets. If random data were used then the correlation value goes to virtually zero. There is little to no lateral offset of the depth of basinal features although there is a tendency for the Tilt-Depth results to be slightly shallower than the drill depths. We also applied the Tilt-Depth method to a local-scale, relatively high-resolution aeromagnetic survey over the Olympic Peninsula of Washington State. The Tilt-Depth method successfully identified a variety of important tectonic elements known from geological mapping. Of particular interest, the Tilt-Depth method illuminated deep (3km) contacts within the non-magnetic sedimentary core of the Olympic Mountains, where magnetic anomalies are subdued and low in amplitude. For Australia, the Tilt-Depth estimates also give a good correlation with known areas of shallow basement and sedimentary basins. Our estimates of basement depth are not restricted to regional analysis but work equally well at the micro scale (basin scale) with depth estimates agreeing well with drill hole and seismic data. We focus on the eastern Officer Basin as an example of basin scale studies and find a good level of agreement between previously-derived basin models. However, our study potentially reveals depocentres not previously mapped due to the sparse distribution of well data. This example thus shows the potential additional advantage of the method in geological interpretation. The success of this study suggests that the Tilt-Depth method is useful in estimating the depth to crystalline basement when appropriate quality aeromagnetic anomaly data are used (i.e. line spacing on the order of or less than the expected depth to

  14. A New Method for Tracking Individual Particles During Bed Load Transport in a Gravel-Bed River

    Science.gov (United States)

    Tremblay, M.; Marquis, G. A.; Roy, A. G.; Chaire de Recherche Du Canada En Dynamique Fluviale

    2010-12-01

    Many particle tracers (passive or active) have been developed to study gravel movement in rivers. It remains difficult, however, to document resting and moving periods and to know how particles travel from one deposition site to another. Our new tracking method uses the Hobo Pendant G acceleration Data Logger to quantitatively describe the motion of individual particles from the initiation of movement, through the displacement and to the rest, in a natural gravel river. The Hobo measures the acceleration in three dimensions at a chosen temporal frequency. The Hobo was inserted into 11 artificial rocks. The rocks were seeded in Ruisseau Béard, a small gravel-bed river in the Yamaska drainage basin (Québec) where the hydraulics, particle sizes and bed characteristics are well known. The signals recorded during eight floods (Summer and Fall 2008-2009) allowed us to develop an algorithm which classifies the periods of rest and motion. We can differentiate two types of motion: sliding and rolling. The particles can also vibrate while remaining in the same position. The examination of the movement and vibration periods with respect to the hydraulic conditions (discharge, shear stress, stream power) showed that vibration occurred mostly before the rise of hydrograph and allowed us to establish movement threshold and response times. In all cases, particle movements occurred during floods but not always in direct response to increased bed shear stress and stream power. This method offers great potential to track individual particles and to establish a spatiotemporal sequence of the intermittent transport of the particle during a flood and to test theories concerning the resting periods of particles on a gravel bed.

  15. Geomechanics of bedded salt

    International Nuclear Information System (INIS)

    Serata, S.; Milnor, S.W.

    1979-01-01

    Creep data from the literature search is reinterpreted by SGI, resulting in a better understanding of the temperature and stress state dependence of the octahedral creep rate and the octahedral shear strength. The concept of a transition strength between the elastic and the plastic states is in agreement with the data. The elastic and rheological properties of salt are described, and a set of constitutive equations is presented. The dependence of material properties on parameters such as temperature is considered. Findings on the permeability of salt are summarized, and the in-situ behavior of openings in bedded salt is described based on extensive engineering experience. A stress measuring system utilizing a finite element computer code is discussed. Geological factors affecting the stability of salt openings are considered, and the Stress Control Technique for designing stable openings in bedded salt formations is explained

  16. V/STOL tilt rotor aircraft study. Volume 6: Preliminary design of a composite wing for tilt rotor research aircraft

    Science.gov (United States)

    Soule, V. A.; Badri-Nath, Y.

    1973-01-01

    The results of a study of the use of composite materials in the wing of a tilt rotor aircraft are presented. An all-metal tilt rotor aircraft was first defined to provide a basis for comparing composite with metal structure. A configuration study was then done in which the wing of the metal aircraft was replaced with composite wings of varying chord and thickness ratio. The results of this study defined the design and performance benefits obtainable with composite materials. Based on these results the aircraft was resized with a composite wing to extend the weight savings to other parts of the aircraft. A wing design was then selected for detailed structural analysis. A development plan including costs and schedules to develop this wing and incorporate it into a proposed flight research tilt rotor vehicle has been devised.

  17. Reproducibility of heart rate variability, blood pressure variability and baroreceptor sensitivity during rest and head-up tilt

    DEFF Research Database (Denmark)

    Højgaard, Michael V; Agner, Erik; Kanters, Jørgen K

    2005-01-01

    OBJECTIVE: Previous studies have indicated moderate-to-poor reproducibility of heart rate variability (HRV) but the reproducibility of blood pressure variability (BPV) and spectral measures of baroreceptor sensitivity (BRS) are not well established. METHODS: We measured normal-to-normal heart beat...... pressures were extracted for the assessment of day-to-day and short-term reproducibility. Power spectrum analysis (Fourier) and transfer function analysis was performed. Reproducibility was assessed using the coefficient of variation (CV). The reproducibility of the mean RR interval, mean systolic......, diastolic and mean blood pressure was good (CVspectral parameters of HRV (CV range 18-36%) and BPV (16-44%) and moderate reproducibility of BRS (14-20%). CONCLUSION: Spectral estimates of BRS had only moderate reproducibility although...

  18. RESTful web services with Dropwizard

    CERN Document Server

    Dallas, Alexandros

    2014-01-01

    A hands-on focused step-by-step tutorial to help you create Web Service applications using Dropwizard. If you are a software engineer or a web developer and want to learn more about building your own Web Service application, then this is the book for you. Basic knowledge of Java and RESTful Web Service concepts is assumed and familiarity with SQL/MySQL and command-line scripting would be helpful.

  19. Patient Specific Modeling of Head-Up Tilt

    DEFF Research Database (Denmark)

    Williams, Nakeya; Wright, Andrew; Mehlsen, Jesper

    2014-01-01

    Short term cardiovascular responses to head-up tilt (HUT) experiments involve complex cardiovascular regulation in order to maintain blood pressure at homeostatic levels. This manuscript presents a patient specific compartmental model developed to predict dynamic changes in heart rate and arterial...

  20. Tilted axis rotation in odd-odd {sup 164}Tm

    Energy Technology Data Exchange (ETDEWEB)

    Reviol, W.; Riedinger, L.L.; Wang, X.Z.; Zhang, J.Y. [Univ. of Tennessee, Knoxville, TN (United States)] [and others

    1996-12-31

    Ten band structures are observed in {sup 164}Tm, among them sets of parallel and anti-parallel couplings of the proton and neutron spins. The Tilted Axis Cranking scheme is applied for the first time to an odd-odd nucleus in a prominent region of nuclear deformation.

  1. The dynamic performance of narrow actively tilting vehicles

    NARCIS (Netherlands)

    Pauwelussen, J.P.

    2000-01-01

    The major advantage of a motorcycle with respect to a passenger car is the possibility of the driver to tilt during cornering and thereby maintaining stability whereas a passenger car will suffer from the risk of capsizing at high speed. This observation has motivated recently various manufacturers

  2. Correlation between length and tilt of lipid tails

    Energy Technology Data Exchange (ETDEWEB)

    Kopelevich, Dmitry I., E-mail: dkopelevich@che.ufl.edu [Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611 (United States); Nagle, John F., E-mail: nagle@cmu.edu [Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)

    2015-10-21

    It is becoming recognized from simulations, and to a lesser extent from experiment, that the classical Helfrich-Canham membrane continuum mechanics model can be fruitfully enriched by the inclusion of molecular tilt, even in the fluid, chain disordered, biologically relevant phase of lipid bilayers. Enriched continuum theories then add a tilt modulus κ{sub θ} to accompany the well recognized bending modulus κ. Different enrichment theories largely agree for many properties, but it has been noticed that there is considerable disagreement in one prediction; one theory postulates that the average length of the hydrocarbon chain tails increases strongly with increasing tilt and another predicts no increase. Our analysis of an all-atom simulation favors the latter theory, but it also shows that the overall tail length decreases slightly with increasing tilt. We show that this deviation from continuum theory can be reconciled by consideration of the average shape of the tails, which is a descriptor not obviously includable in continuum theory.

  3. Simulations of Micropumps Based on Tilted Flexible Fibers

    Science.gov (United States)

    Hancock, Matthew; Elabbasi, Nagi; Demirel, Melik

    2015-11-01

    Pumping liquids at low Reynolds numbers is challenging because of the principle of reversibility. We report here a class of microfluidic pump designs based on tilted flexible structures that combines the concepts of cilia (flexible elastic elements) and rectifiers (e.g., Tesla valves, check valves). We demonstrate proof-of-concept with 2D and 3D fluid-structure interaction (FSI) simulations in COMSOL Multiphysics®of micropumps consisting of a source for oscillatory fluidic motion, e.g. a piston, and a channel lined with tilted flexible rods or sheets to provide rectification. When flow is against the rod tilt direction, the rods bend backward, narrowing the channel and increasing flow resistance; when flow is in the direction of rod tilt, the rods bend forward, widening the channel and decreasing flow resistance. The 2D and 3D simulations involve moving meshes whose quality is maintained by prescribing the mesh displacement on guide surfaces positioned on either side of each flexible structure. The prescribed displacement depends on structure bending and maintains mesh quality even for large deformations. Simulations demonstrate effective pumping even at Reynolds numbers as low as 0.001. Because rod rigidity may be specified independently of Reynolds number, in principle, rod rigidity may be reduced to enable pumping at arbitrarily low Reynolds numbers.

  4. Dynamic characteristics of polymer faced tilting pad journal bearings

    DEFF Research Database (Denmark)

    Simmons, Gregory F.; Cerda Varela, Alejandro Javier; Santos, Ilmar

    2014-01-01

    Dynamic characteristics of polymer faced tilting pad journal bearings are presented. Investigations are conducted using a single pad, load on pad configuration over a range of shaft speeds and loads. Two polyether ether ketone (PEEK) faced pads, one polytetrafluoroethylene (PTFE) faced pad and two...

  5. Analysis of a ferrofluid core differential transformer tilt measurement sensor

    Energy Technology Data Exchange (ETDEWEB)

    Medvegy, T.; Molnár, Á.; Molnár, G.; Gugolya, Z.

    2017-04-15

    In our work, we developed a ferrofluid core differential transformer sensor, which can be used to measure tilt and acceleration. The proposed sensor consisted of three coils, from which the primary was excited with an alternating current. In the space surrounded by the coils was a cell half-filled with ferrofluid, therefore in the horizontal state of the sensor the fluid distributes equally in the three sections of the cell surrounded by the three coils. Nevertheless when the cell is being tilted or accelerated (in the direction of the axis of the coils), there is a different amount of ferrofluid in the three sections. The voltage induced in the secondary coils strongly depends on the amount of ferrofluid found in the core surrounded by them, so the tilt or the acceleration of the cell becomes measurable. We constructed the sensor in several layouts. The linearly coiled sensor had an excellent resolution. Another version with a toroidal cell had almost perfect linearity and a virtually infinite measuring range. - Highlights: • A ferrofluid core differential transformer can be used to measure tilt. • The theoretical description of two different type of the sensor is introduced. • The measuring range, and the sensitivity depends on the dimensions of the sensor.

  6. Performance of a Tilt Current Meter in the Surf Zone

    DEFF Research Database (Denmark)

    Hansen, Asger Bendix; Carstensen, Stefan; Christensen, Drude Fritzbøger

    2017-01-01

    Tilt Current Meters (TCM’s) are relatively simple and inexpensive instruments for measuring currents in rivers and inthe sea. Their low cost and easy deployment means that a relatively large number of TCM’s can be deployed comparedto more conventional current meters such as Acoustic Doppler...

  7. The impact of gravity during head-up tilt

    DEFF Research Database (Denmark)

    Ottesen, Johnny T.; Olufsen, Mette; Smith, Brittany

    2011-01-01

    The impact of gravity during head-up tilt, a test often used in the clinic to diagnose patients who suffer from dizziness or frequent episodes of syncope, is not well described. This study uses mathematical modeling to analyze experimental blood pressure data measured at the level of the aorta an...

  8. Development of tilted fibre Bragg gratings using highly coherent 255 ...

    Indian Academy of Sciences (India)

    R&D C-1 Block, Raja Ramanna Centre for Advanced Technology, Indore 452 013, India. ∗. Corresponding author. E-mail: oprakash@rrcat.gov.in. DOI: 10.1007/s12043-013-0672-7; ePublication: 6 February 2014. Abstract. This paper reports the study on development of tilted fibre Bragg gratings using highly coherent 255 ...

  9. Impaired perception of surface tilt in progressive supranuclear palsy.

    Directory of Open Access Journals (Sweden)

    Marian L Dale

    Full Text Available Progressive supranuclear palsy (PSP is characterized by early postural instability and backward falls. The mechanisms underlying backward postural instability in PSP are not understood. The aim of this study was to test the hypothesis that postural instability in PSP is a result of dysfunction in the perception of postural verticality.We gathered posturography data on 12 subjects with PSP to compare with 12 subjects with idiopathic Parkinson's Disease (PD and 12 healthy subjects. Objective tests of postural impairment included: dynamic sensory perception tests of gravity and of surface oscillations, postural responses to surface perturbations, the sensory organization test of postural sway under altered sensory conditions and limits of stability in stance.Perception of toes up (but not toes down surface tilt was reduced in subjects with PSP compared to both control subjects (p≤0.001 standing, p≤0.007 seated and subjects with PD (p≤0.03 standing, p≤0.04 seated. Subjects with PSP, PD and normal controls accurately perceived the direction of gravity when standing on a tilting surface. Unlike PD and control subjects, subjects with PSP exerted less postural corrective torque in response to toes up surface tilts.Difficulty perceiving backward tilt of the surface or body may account for backward falls and postural impairments in patients with PSP. These observations suggest that abnormal central integration of sensory inputs for perception of body and surface orientation contributes to the pathophysiology of postural instability in PSP.

  10. WEB-SERVICE. RESTFUL ARCHITECTURE

    Directory of Open Access Journals (Sweden)

    M. Melnichuk

    2018-04-01

    Full Text Available Network technology for interaction between two applications via the HTTP protocol was considered in article.When client works with REST API - it means it works with "resources", and in SOAP work is performed with operations. To build REST web services, you must follow certain principles: explicit use of HTTP methods, access to resources by URI, stateless, HATEAOS, caching, transfer of objects in JSON or XML representation. But sometimes some principles are ignored to ensure a higher speed of work and to reduce development time.The pros and cons of using JSON and XML representations were considered, and it can be said that using the JSON format reduces the amount of data transfer, and with the use of XML, the readability of data increases.Also, two main ways of data transfer in REST web services were considered: converting the file to Base64 and transferring it as an object field or transferring the file using the usual HTTP multipart. The Base64 standard approach gives a higher speed for multiple files in a single request, because only one HTTP connection is created, but these files are stored in RAM during request processing, which increases chance of the application crashing.In the conclusion, the advantages of using web services and their wide use in other architectural approaches were considered, which increases the popularity of web services.

  11. The long-term persistence of phytoplankton resting stages in aquatic "seed banks"

    DEFF Research Database (Denmark)

    Ellegaard, Marianne; Ribeiro, Sofia

    2018-01-01

    to terrestrial seed beds of vascular plants, but are much less studied. It is therefore timely to review the phenomenon of long-term persistence of aquatic resting stages in sediment seed banks. Herein we compare function, morphology and physiology of phytoplankton resting stages to factors central...... for persistence of terrestrial seeds. We review the types of resting stages found in different groups of phytoplankton and focus on the groups for which long-term (multi-decadal) persistence has been shown: dinoflagellates, diatoms, green algae and cyanobacteria. We discuss the metabolism of long-term dormancy......In the past decade, research on long-term persistence of phytoplankton resting stages has intensified. Simultaneously, insight into life-cycle variability in the diverse groups of phytoplankton has also increased. Aquatic 'seed banks' have tremendous significance and show many interesting parallels...

  12. Novel tilt-curvature coupling in lipid membranes

    Science.gov (United States)

    Terzi, M. Mert; Deserno, Markus

    2017-08-01

    On mesoscopic scales, lipid membranes are well described by continuum theories whose main ingredients are the curvature of a membrane's reference surface and the tilt of its lipid constituents. In particular, Hamm and Kozlov [Eur. Phys. J. E 3, 323 (2000)] have shown how to systematically derive such a tilt-curvature Hamiltonian based on the elementary assumption of a thin fluid elastic sheet experiencing internal lateral pre-stress. Performing a dimensional reduction, they not only derive the basic form of the effective surface Hamiltonian but also express its emergent elastic couplings as trans-membrane moments of lower-level material parameters. In the present paper, we argue, though, that their derivation unfortunately missed a coupling term between curvature and tilt. This term arises because, as one moves along the membrane, the curvature-induced change of transverse distances contributes to the area strain—an effect that was believed to be small but nevertheless ends up contributing at the same (quadratic) order as all other terms in their Hamiltonian. We illustrate the consequences of this amendment by deriving the monolayer and bilayer Euler-Lagrange equations for the tilt, as well as the power spectra of shape, tilt, and director fluctuations. A particularly curious aspect of our new term is that its associated coupling constant is the second moment of the lipid monolayer's lateral stress profile—which within this framework is equal to the monolayer Gaussian curvature modulus, κ¯ m. On the one hand, this implies that many theoretical predictions now contain a parameter that is poorly known (because the Gauss-Bonnet theorem limits access to the integrated Gaussian curvature); on the other hand, the appearance of κ¯ m outside of its Gaussian curvature provenance opens opportunities for measuring it by more conventional means, for instance by monitoring a membrane's undulation spectrum at short scales.

  13. Modeling Flow Past a Tilted Vena Cava Filter

    Energy Technology Data Exchange (ETDEWEB)

    Singer, M A; Wang, S L

    2009-06-29

    Inferior vena cava filters are medical devices used to prevent pulmonary embolism (PE) from deep vein thrombosis. In particular, retrievable filters are well-suited for patients who are unresponsive to anticoagulation therapy and whose risk of PE decreased with time. The goal of this work is to use computational fluid dynamics to evaluate the flow past an unoccluded and partially occluded Celect inferior vena cava filter. In particular, the hemodynamic response to thrombus volume and filter tilt is examined, and the results are compared with flow conditions that are known to be thrombogenic. A computer model of the filter inside a model vena cava is constructed using high resolution digital photographs and methods of computer aided design. The models are parameterized using the Overture software framework, and a collection of overlapping grids is constructed to discretize the flow domain. The incompressible Navier-Stokes equations are solved, and the characteristics of the flow (i.e., velocity contours and wall shear stresses) are computed. The volume of stagnant and recirculating flow increases with thrombus volume. In addition, as the filter increases tilt, the cava wall adjacent to the tilted filter is subjected to low velocity flow that gives rise to regions of low wall shear stress. The results demonstrate the ease of IVC filter modeling with the Overture software framework. Flow conditions caused by the tilted Celect filter may elevate the risk of intrafilter thrombosis and facilitate vascular remodeling. This latter condition also increases the risk of penetration and potential incorporation of the hook of the filter into the vena caval wall, thereby complicating filter retrieval. Consequently, severe tilt at the time of filter deployment may warrant early clinical intervention.

  14. Rest requirements and rest management of personnel in shift work

    Energy Technology Data Exchange (ETDEWEB)

    Hammell, B.D. [PDG Environmental, Melbourne, FL (United States); Scheuerle, A. [Univ. of Texas, Houston, TX (United States)

    1995-12-31

    A difficulty-weighted shift assignment scheme is proposed for use in prolonged and strenuous field operations such as emergency response, site testing, and short term hazardous waste remediation projects. The purpose of the work rotation plan is to increase productivity, safety, and moral of workers. Job weighting is accomplished by assigning adjustments to the mental and physical intensity of the task, the protective equipment worn, and the climatic conditions. The plan is based on medical studies of sleep deprivation, the effects of rest adjustments, and programs to reduce sleep deprivation and normalize shift schedules.

  15. Motion sickness and tilts of the inertial force environment : Active suspension systems vs. active passengers

    NARCIS (Netherlands)

    Golding, J. F.; van der Bles, W.; Bos, J. E.; Haynes, T.; Gresty, M. A.

    2003-01-01

    Background: Maneuvering in vehicles exposes occupants to low frequency forces (<1 Hz) which can provoke motion sickness. Hypothesis: Aligning with the tilting inertial resultant (gravity + imposed horizontal acceleration: gravito-inertial force (GIF)) may reduce motion sickness when tilting is

  16. Coal Bed Methane Primer

    Energy Technology Data Exchange (ETDEWEB)

    Dan Arthur; Bruce Langhus; Jon Seekins

    2005-05-25

    During the second half of the 1990's Coal Bed Methane (CBM) production increased dramatically nationwide to represent a significant new source of income and natural gas for many independent and established producers. Matching these soaring production rates during this period was a heightened public awareness of environmental concerns. These concerns left unexplained and under-addressed have created a significant growth in public involvement generating literally thousands of unfocused project comments for various regional NEPA efforts resulting in the delayed development of public and fee lands. The accelerating interest in CBM development coupled to the growth in public involvement has prompted the conceptualization of this project for the development of a CBM Primer. The Primer is designed to serve as a summary document, which introduces and encapsulates information pertinent to the development of Coal Bed Methane (CBM), including focused discussions of coal deposits, methane as a natural formed gas, split mineral estates, development techniques, operational issues, producing methods, applicable regulatory frameworks, land and resource management, mitigation measures, preparation of project plans, data availability, Indian Trust issues and relevant environmental technologies. An important aspect of gaining access to federal, state, tribal, or fee lands involves education of a broad array of stakeholders, including land and mineral owners, regulators, conservationists, tribal governments, special interest groups, and numerous others that could be impacted by the development of coal bed methane. Perhaps the most crucial aspect of successfully developing CBM resources is stakeholder education. Currently, an inconsistent picture of CBM exists. There is a significant lack of understanding on the parts of nearly all stakeholders, including industry, government, special interest groups, and land owners. It is envisioned the Primer would being used by a variety of

  17. Infant's bed climate and bedding in the Japanese home.

    Science.gov (United States)

    Nakamura Ikeda, Rie; Fukai, Kiyoko; Okamoto Mizuno, Kazue

    2012-06-01

    to assess the bed climate of infants in their homes in Japan. descriptive, exploratory, non-experimental research design. the data were collected at the participants' homes under normal circumstances. nineteen healthy infants between the ages of two and five months. Their mothers, who joined a parenting class organised by a maternity clinic in Okayama, Japan, consented to participate in this study. we visited the infants' homes and interviewed their mothers concerning the types and use of bedding. The temperature and relative humidity of the bed climate at the back and foot of the bedding, and in the room were measured every minute for four consecutive days. Differences among the bed climates measured during three seasons (spring, summer, and autumn) were assessed by one-way analysis of variance. The bed temperature was higher for infants than for adults. No significant difference in temperature was noted among the three seasons. The bed temperature was about 36.0°C when waterproof sheets and futon mattresses for children or adult were used. The average relative humidity of the bed climate at the back was highest in summer, followed by that in spring and autumn; the differences were significant. The use of waterproof sheets and futon mattresses for children in summer increased the relative humidity to 80% or more. The use of infant beds, sunoko drainboards, and cotton futon mattresses in summer was effective in reducing the bed humidity. these results suggest that nurse-midwives should advise the parents on comfortable bed climates for their infants, as well as how to select and use bedding for them. Copyright © 2010 Elsevier Ltd. All rights reserved.

  18. Particle bed reactor modeling

    Science.gov (United States)

    Sapyta, Joe; Reid, Hank; Walton, Lew

    The topics are presented in viewgraph form and include the following: particle bed reactor (PBR) core cross section; PBR bleed cycle; fuel and moderator flow paths; PBR modeling requirements; characteristics of PBR and nuclear thermal propulsion (NTP) modeling; challenges for PBR and NTP modeling; thermal hydraulic computer codes; capabilities for PBR/reactor application; thermal/hydralic codes; limitations; physical correlations; comparison of predicted friction factor and experimental data; frit pressure drop testing; cold frit mask factor; decay heat flow rate; startup transient simulation; and philosophy of systems modeling.

  19. Fluidised bed cereal cooking

    International Nuclear Information System (INIS)

    Jenkins, Simon Anthony

    2002-01-01

    Man has been cooking food for thousands of years for a number of reasons: to improve flavour and palatability, sterilise, increase digestibility, improve texture and colour. Increasingly more advanced techniques are employed today in food production plants to engineer foods with many different properties. With this in mind manufacturers are constantly seeking to improve processing techniques and apply new or different technologies (such as microwaves, RF and extrusion) to develop foods with new properties (like puffed texture starches) and to increase process efficiencies (energy efficiency, water reduction). This thesis reports on work undertaken to demonstrate the potential to achieve high temperature starch conversion of whole wheat grains in a fluidised bed, thereby reducing the amount of water required and processing time. Specifically, wheat from the farm at 14% water content is cooked in a fluidised bed. The fluidised bed heats the wheat quickly by convective heating. In addition, energy can be delivered directly to the grain by microwave heating during fluidisation. Degree of starch conversion is determined by measuring the reduction in size of endotherm of reaction as observed by Differential Scanning Calorimetry. The fluidising gas, processing temperature and starting moisture content were varied in order to investigate their effect on the cooking process. A mathematical model based on energy and species concentration equations was developed to help understand the internal grain processes. The model coupled the thermal energy equation with water diffusion. The effect of water evaporation was represented as a thermal sink in the energy equation. Popular kinetic models from literature were adapted to predict the degree of starch conversion. The model gives solutions consistent with experimental data and physical intuition. A commercial computational fluid dynamics package was used to study simple airflow and particle tracks in the fluidisation column. A

  20. Sustainable Rest Area Design and Operations

    Science.gov (United States)

    2017-10-01

    One way in which State Departments of Transportation (DOTs) can modernize their rest areas while reducing operations and maintenance costs is by incorporating sustainable practices into rest area design and operations. Sustainability practices that D...

  1. Experimentally determined distribution of granular-flow characteristics in collisional bed load transport

    Directory of Open Access Journals (Sweden)

    Matoušek Václav

    2018-01-01

    Full Text Available A series of laboratory experiments on turbulent open-channel two-phase flow in a form of intense bed load transport is reported. Measurements in a laboratory tilting flume included camera based imaging techniques to identify the structure of the flow at the local level. Obtained experimental distributions of two-phase flow related parameters - granular velocity, concentration, and temperature - across a collisional transport layer are discussed. The results are analysed together with additional measured quantities (discharges of mixture and grains, flow depth, bed slope etc. Our major goal is to evaluate the distribution of granular stresses across the transport layer with a special attention paid to the interface between the transport layer and the bed. Furthermore, comparisons are discussed between the experimental results and predictions produced by suitable kinetic-theory based models.

  2. Temporal organization of rest defined by actigraphy data in healthy and childhood chronic fatigue syndrome children.

    Science.gov (United States)

    Kawabata, Minako; Ueno, Taro; Tomita, Jun; Kawatani, Junko; Tomoda, Akemi; Kume, Shoen; Kume, Kazuhiko

    2013-11-04

    Accumulating evidence has shown a universality in the temporal organization of activity and rest among animals ranging from mammals to insects. Previous reports in both humans and mice showed that rest bout durations followed long-tailed (i.e., power-law) distributions, whereas activity bouts followed exponential distributions. We confirmed similar results in the fruit fly, Drosophila melanogaster. Conversely, another report showed that the awakening bout durations, which were defined by polysomnography in bed, followed power-law distributions, while sleeping periods, which may correspond to rest, followed exponential distributions. This apparent discrepancy has been left to be resolved. Actigraphy data from healthy and disordered children were analyzed separately for two periods: time out of bed (UP period) and time in bed (DOWN period). When data over a period of 24 h were analyzed as a whole, rest bouts showed a power law distribution as previously reported. However, when UP and DOWN period data were analyzed separately, neither showed power law properties. Using a newly developed strict method, only 30% of individuals satisfied the power law criteria, even when the 24 h data were analyzed. The human results were in contrast to the Drosophila results, which revealed clear power-law distributions for both day time and night time rest through the use of a strict method. In addition, we analyzed the actigraphy data from patients with childhood type chronic fatigue syndrome (CCFS), and found that they showed differences from healthy controls when their UP and DOWN data were analyzed separately. These results suggested that the DOWN sleep, the bout distribution of which showed exponential properties, contributes to the production of long-tail distributions in human rest periods. We propose that separate analysis of UP and DOWN period data is important for understanding the temporal organization of activity.

  3. Perception of self-tilt in a true and illusory vertical plane

    Science.gov (United States)

    Groen, Eric L.; Jenkin, Heather L.; Howard, Ian P.; Oman, C. M. (Principal Investigator)

    2002-01-01

    A tilted furnished room can induce strong visual reorientation illusions in stationary subjects. Supine subjects may perceive themselves upright when the room is tilted 90 degrees so that the visual polarity axis is kept aligned with the subject. This 'upright illusion' was used to induce roll tilt in a truly horizontal, but perceptually vertical, plane. A semistatic tilt profile was applied, in which the tilt angle gradually changed from 0 degrees to 90 degrees, and vice versa. This method produced larger illusory self-tilt than usually found with static tilt of a visual scene. Ten subjects indicated self-tilt by setting a tactile rod to perceived vertical. Six of them experienced the upright illusion and indicated illusory self-tilt with an average gain of about 0.5. This value is smaller than with true self-tilt (0.8), but comparable to the gain of visually induced self-tilt in erect subjects. Apparently, the contribution of nonvisual cues to gravity was independent of the subject's orientation to gravity itself. It therefore seems that the gain of visually induced self-tilt is smaller because of lacking, rather than conflicting, nonvisual cues. A vector analysis is used to discuss the results in terms of relative sensory weightings.

  4. Restful API Architecture Based on Laravel Framework

    Science.gov (United States)

    Chen, Xianjun; Ji, Zhoupeng; Fan, Yu; Zhan, Yongsong

    2017-10-01

    Web service has been an industry standard tech for message communication and integration between heterogeneous systems. RESTFUL API has become mainstream web service development paradigm after SOAP, how to effectively construct RESTFUL API remains a research hotspots. This paper presents a development model of RESTFUL API construction based on PHP language and LARAVEL framework. The key technical problems that need to be solved during the construction of RESTFUL API are discussed, and implementation details based on LARAVEL are given.

  5. Fluidized bed boiler feed system

    Science.gov (United States)

    Jones, Brian C.

    1981-01-01

    A fluidized bed boiler feed system for the combustion of pulverized coal. Coal is first screened to separate large from small particles. Large particles of coal are fed directly to the top of the fluidized bed while fine particles are first mixed with recycled char, preheated, and then fed into the interior of the fluidized bed to promote char burnout and to avoid elutriation and carryover.

  6. ADVANCES IN CLOG STATE MONITORING FOR USE IN AUTOMATED REED BED INSTALLATIONS

    Directory of Open Access Journals (Sweden)

    Theodore HUGHES-RILEY

    2014-06-01

    Full Text Available Constructed wetlands are a popular form of waste-water treatment that have proliferated across Europe and the rest of the world in recent years as an environmentally conscious form of waste water treatment. The ability to monitor the conditions in the bed and control input factors such as heating and aeration may extend the lifetime of the reed bed substantially beyond the ten year lifetime normally reached. The Autonomous Reed Bed Installation (ARBI project is an EU FP7 initiative to develop a reed bed with automated control over input parameters based on readings taken from embedded sensors. Automated remedial action may improve bed treatment efficiency, and prolong the life of the bed and avoiding the need to refurbish the bed, which is both time consuming and costly. One critical parameter to observe is the clog state of the reed bed, as this can severely impact on the efficiency of water treatment to the point of the bed becoming non-operable. Magnetic resonance (MR sensors can be a powerful tool in determining clogging levels, and has previously been explored in the literature. This work is based on a conference paper (2nd International Conference "Water resources and wetlands", 2014 and details magnetic sensors suitable for long-term embedding into a constructed wetland. Unlike previous studies this work examines a probe embedded into a wetland.

  7. Management bedding : vrijloopstal met composterende bedding van houtsnippers

    NARCIS (Netherlands)

    Boer, de H.C.; Wiersma, M.; Galama, P.J.; Szanto, G.L.

    2015-01-01

    In de vrijloopstal liggen de koeien meestal op een organische bedding en scheiden daar mest (feces en urine) uit. Om de bedding voldoende droog en schoon te houden wordt er regelmatig nieuw strooisel aangevoerd en wordt de toplaag bewerkt. Op basis van onderzoek- en praktijkervaringen tot nu toe

  8. Tilting-Pad Guide Bearing in Large Hydro-unit

    Directory of Open Access Journals (Sweden)

    Li-Feng Ma

    2000-01-01

    Full Text Available A new numerical method is proposed for predicting the nonlinearity of tilting-pad guide bearing oilfilm force in the rotor-bearing system in a large hydro-unit. Nonlinear displacement and velocity of the journal center, as well as nonlinear tilting angles and angular velocities of the pads in non-stationary Reynolds equation are taken into account. This method is also suited for other small rotor-bearing system. As an example, the response due to a momentarily created unbalance is Calculated. The nonlinear motion patterns of the pad and journal whirling orbit are obtained. Finally, the nonlinear orbit is compared to the linear one that could be calculated from linear stiffness and damping coefficients. It is shown that there are important differences between those two orbits and that the nonlinear simulation is more accurate.

  9. Friction and Lubrication of Large Tilting-Pad Thrust Bearings

    Directory of Open Access Journals (Sweden)

    Michał Wasilczuk

    2015-04-01

    Full Text Available Fluid film bearings have been extensively used in the industry because of their unbeatable durability and extremely low friction coefficient, despite a very low coefficient of friction dissipation of energy being noticeable, especially in large bearings. Lubricating systems of large tilting pad thrust bearings utilized in large, vertical shaft hydrogenerators are presented in this paper. A large amount of heat is generated due to viscous shearing of the lubricant large tilting pad thrust bearings, and this requires systems for forced cooling of the lubricant. In the dominant bath lubrication systems, cooling is realized by internal coolers or external cooling systems, with the latter showing some important advantages at the cost of complexity and also, potentially, lower reliability. Substantial losses in the bearings, reaching 1 MW in extreme cases, are a good motivation for the research and development aimed at reducing them. Some possible methods and their potential efficiency, along with some effects already documented, are also described in the paper.

  10. Profile stabilization of tilt mode in a Field Reversed Configuration

    Energy Technology Data Exchange (ETDEWEB)

    Cobb, J.W.; Tajima, T. [Texas Univ., Austin, TX (United States). Inst. for Fusion Studies; Barnes, D.C. [Los Alamos National Lab., NM (United States)

    1993-06-01

    The possibility of stabilizing the tilt mode in Field Reversed Configurations without resorting to explicit kinetic effects such as large ion orbits is investigated. Various pressure profiles, P({Psi}), are chosen, including ``hollow`` profiles where current is strongly peaked near the separatrix. Numerical equilibria are used as input for an initial value simulation which uses an extended Magnetohydrodynamic (MHD) model that includes viscous and Hall terms. Tilt stability is found for specific hollow profiles when accompanied by high values of separatrix beta, {beta}{sub sep}. The stable profiles also have moderate to large elongation, racetrack separatrix shape, and lower values of 3, average ratio of Larmor radius to device radius. The stability is unaffected by changes in viscosity, but the neglect of the Hall term does cause stable results to become marginal or unstable. Implications for interpretation of recent experiments are discussed.

  11. Profile stabilization of tilt mode in a Field Reversed Configuration

    International Nuclear Information System (INIS)

    Cobb, J.W.; Tajima, T.

    1993-06-01

    The possibility of stabilizing the tilt mode in Field Reversed Configurations without resorting to explicit kinetic effects such as large ion orbits is investigated. Various pressure profiles, P(Ψ), are chosen, including ''hollow'' profiles where current is strongly peaked near the separatrix. Numerical equilibria are used as input for an initial value simulation which uses an extended Magnetohydrodynamic (MHD) model that includes viscous and Hall terms. Tilt stability is found for specific hollow profiles when accompanied by high values of separatrix beta, β sep . The stable profiles also have moderate to large elongation, racetrack separatrix shape, and lower values of 3, average ratio of Larmor radius to device radius. The stability is unaffected by changes in viscosity, but the neglect of the Hall term does cause stable results to become marginal or unstable. Implications for interpretation of recent experiments are discussed

  12. On the Design of Tilting-Pad Thrust Bearings

    DEFF Research Database (Denmark)

    Heinrichson, Niels

    2007-01-01

    Pockets are often machined in the surfaces of tilting-pad thrust bearings to allow for hydrostatic jacking in the start-up phase. Pockets and other recesses in the surfaces of bearing pads influence the pressure distribution and thereby the position of the pivot resulting in the most advantageous...... based on the Reynolds equation are used. They include the effects of variations of viscosity with temperature and the deformation of the bearing pads due to pressure and thermal gradients. The models are validated using measurements. Tilting-pad bearings of standard design are studied and the influences...... of the friction loss. Both this bearing and the bearing design with enclosed recesses in the high-pressure regions of the pads suffer from a higher sensitivity to the position of the pivot. The design of such bearing is therefore no trivial task....

  13. Cellular structures using U_q-tilting modules

    DEFF Research Database (Denmark)

    Andersen, Henning Haahr; Stroppel, Catharina; Tubbenhauer, Daniel

    We use the theory of Uq-tilting modules to construct cellular bases for centralizer algebras. Our methods are quite general and work for any quantum group Uq attached to a Cartan matrix and include the non semi-simple cases for q being a root of unity and ground fields of positive characteristic........ Our approach also generalize to certain categories containing infinite dimensional modules. As an application, we recover several known cellular structures (which can all be fit into our general set-up) as we illustrate in a list of examples.......We use the theory of Uq-tilting modules to construct cellular bases for centralizer algebras. Our methods are quite general and work for any quantum group Uq attached to a Cartan matrix and include the non semi-simple cases for q being a root of unity and ground fields of positive characteristic...

  14. Differential effects of lower body negative pressure and upright tilt on splanchnic blood volume

    Science.gov (United States)

    Taneja, Indu; Moran, Christopher; Medow, Marvin S.; Glover, June L.; Montgomery, Leslie D.; Stewart, Julian M.

    2015-01-01

    Upright posture and lower body negative pressure (LBNP) both induce reductions in central blood volume. However, regional circulatory responses to postural changes and LBNP may differ. Therefore, we studied regional blood flow and blood volume changes in 10 healthy subjects undergoing graded lower-body negative pressure (−10 to −50 mmHg) and 8 subjects undergoing incremental head-up tilt (HUT; 20°, 40°, and 70°) on separate days. We continuously measured blood pressure (BP), heart rate, and regional blood volumes and blood flows in the thoracic, splanchnic, pelvic, and leg segments by impedance plethysmography and calculated regional arterial resistances. Neither LBNP nor HUT altered systolic BP, whereas pulse pressure decreased significantly. Blood flow decreased in all segments, whereas peripheral resistances uniformly and significantly increased with both HUT and LBNP. Thoracic volume decreased while pelvic and leg volumes increased with HUT and LBNP. However, splanchnic volume changes were directionally opposite with stepwise decreases in splanchnic volume with LBNP and stepwise increases in splanchnic volume during HUT. Splanchnic emptying in LBNP models regional vascular changes during hemorrhage. Splanchnic filling may limit the ability of the splanchnic bed to respond to thoracic hypovolemia during upright posture. PMID:17085534

  15. Why is it so difficult to tilt Uranus?

    Science.gov (United States)

    Rogoszinski, Zeeve; Hamilton, Douglas

    2018-04-01

    The leading hypothesis for the origin of Uranus' large obliquity (98°) is a polar strike from an Earth sized object, but to tilt Saturn similarly would require an impactor roughly 10x as massive. A more likely cause for Saturn's tilt (27°) is a spin-orbit resonance with Neptune (Ward & Hamilton, 2004; Hamilton & Ward, 2004); might the same process work for Uranus? It initially seems unlikely, as at its current location Uranus' axial precession period is too long to resonate with any of the giant planets' orbital precession frequencies. If we place Uranus between Jupiter and Saturn, however, then Uranus' spin axis would precess much more quickly. Thommes et al. (1999, 2002, 2003) first postulated that Uranus and Neptune were formed between Jupiter and Saturn because the conditions there allow the ice giants to be built rapidly. A resonance for our closer Uranus still requires a distant planet, nevertheless, a condition that can be satisfied if Neptune is ejected from Jupiter and Saturn first with Uranus following significantly later. This scenario, while contrived, is consistent with at least some versions of the Nice model and allows us to fully test the resonance hypothesis. We discovered that even with these optimistic assumptions, i) a resonance capture requires a migration timescale on the order of 100 Myr, and ii) it is impossible to tilt Uranus past 90°. Increasing Neptune's migration speed precludes resonant capture, and instead results in a resonance kick. In the most favorable cases, a resonance kick could raise Uranus' obliquity by 40° on a time span of about 50 Myr. We conclude that even in our best scenario, a resonance cannot fully account for Uranus' tilt. We have investigated some scenarios that include both resonances and collisions, and will report on our findings.

  16. Bound Chains of Tilted Dipoles in Layered Systems

    DEFF Research Database (Denmark)

    G. Volosniev, A.; R. Armstrong, J.; V. Fedorov, D.

    2012-01-01

    of an external eletric field. The binding energy and the spatial structure of the bound states are studied in several different ways using analytical approaches. The results are compared to stochastic variational calculations and very good agreement is found. We conclude that approximations based on harmonic...... oscillator potentials are accurate even for tilted dipoles when the geometry of the potential landscape is taken into account....

  17. On the Design of Tilting-Pad Thrust Bearings

    OpenAIRE

    Heinrichson, Niels; Santos, Ilmar

    2007-01-01

    Pockets are often machined in the surfaces of tilting-pad thrust bearings to allow for hydrostatic jacking in the start-up phase. Pockets and other recesses in the surfaces of bearing pads influence the pressure distribution and thereby the position of the pivot resulting in the most advantageous pad convergence ratio. In this thesis, a theoretical approach is applied in the attempt to quantify the influence of recesses in the pad surfaces. The recesses may be relatively deep and enclosed as ...

  18. Simulation of effusion from targets of tilted foils

    International Nuclear Information System (INIS)

    Mustapha, B.; Nolen, J.A.; Gomes, I.C.

    2004-01-01

    Replacing a target transverse to the beam by a 10 times thinner one tilted at about 6 o from the beam direction reduces the thickness for heat transfer and diffusion by a factor of 10 while keeping the same production thickness. This concept makes the target cool faster and therefore supports higher beam power. Monte-Carlo effusion simulations of targets based on this concept were carried out to find optimum target geometries for both fast and slow diffusion materials

  19. Tilt stability of rotating current rings with passive conductors

    International Nuclear Information System (INIS)

    Zweibel, E.G.; Pomphrey, N.

    1984-12-01

    We study the combined effects of rotation and resistive passive conductors on the stability of a rigid current in an external magnetic field. We present numerical and approximate analytical solutions to the equations of motion, which show that the ring is always tilt unstable on the resistive decay timescale of the conductors, although rotation and eddy currents may stabilize it over short times. Possible applications of our model include spheromaks which rotate or which are encircled by energetic particle rings

  20. Discontinuity effects in dynamically loaded tilting pad journal bearings

    DEFF Research Database (Denmark)

    Thomsen, Kim; Klit, Peder; Vølund, Anders

    2011-01-01

    This paper describes two discontinuity effects that can occur when modelling radial tilting pad bearings subjected to high dynamic loads. The first effect to be treated is a pressure build-up discontinuity effect. The second effect is a contact-related discontinuity that disappears when a contact...... force is included in the theoretical model. Methods for avoiding the pressure build-up discontinuity effect are proposed....

  1. An electronic pan/tilt/magnify and rotate camera system

    International Nuclear Information System (INIS)

    Zimmermann, S.; Martin, H.L.

    1992-01-01

    A new camera system has been developed for omnidirectional image-viewing applications that provides pan, tilt, magnify, and rotational orientation within a hemispherical field of view (FOV) without any moving parts. The imaging device is based on the fact that the image from a fish-eye lens, which produces a circular image of an entire hemispherical FOV, can be mathematically corrected using high-speed electronic circuitry. More specifically, an incoming fish-eye image from any image acquisition source is captured in the memory of the device, a transformation is performed for the viewing region of interest and viewing direction, and a corrected image is output as a video image signal for viewing, recording, or analysis. The image transformation device can provide corrected images at frame rates compatible with RS-170 standard video equipment. As a result, this device can accomplish the functions of pan, tilt, rotation, and magnification throughout a hemispherical FOV without the need for any mechanical devices. Multiple images, each with different image magnifications and pan-tilt-rotate parameters, can be obtained from a single camera

  2. Modeling of Tilting-Pad Journal Bearings with Transfer Functions

    Directory of Open Access Journals (Sweden)

    J. A. Vázquez

    2001-01-01

    Full Text Available Tilting-pad journal bearings are widely used to promote stability in modern rotating machinery. However, the dynamics associated with pad motion alters this stabilizing capacity depending on the operating speed of the machine and the bearing geometric parameters, particularly the bearing preload. In modeling the dynamics of the entire rotor-bearing system, the rotor is augmented with a model of the bearings. This model may explicitly include the pad degrees of freedom or may implicitly include them by using dynamic matrix reduction methods. The dynamic reduction models may be represented as a set of polynomials in the eigenvalues of the system used to determine stability. All tilting-pad bearings can then be represented by a fixed size matrix with polynomial elements interacting with the rotor. This paper presents a procedure to calculate the coefficients of polynomials for implicit bearing models. The order of the polynomials changes to reflect the number of pads in the bearings. This results in a very compact and computationally efficient method for fully including the dynamics of tilting-pad bearings or other multiple degrees of freedom components that interact with rotors. The fixed size of the dynamic reduction matrices permits the method to be easily incorporated into rotor dynamic stability codes. A recursive algorithm is developed and presented for calculating the coefficients of the polynomials. The method is applied to stability calculations for a model of a typical industrial compressor.

  3. Numerical tilting compensation in microscopy based on wavefront sensing using transport of intensity equation method

    Science.gov (United States)

    Hu, Junbao; Meng, Xin; Wei, Qi; Kong, Yan; Jiang, Zhilong; Xue, Liang; Liu, Fei; Liu, Cheng; Wang, Shouyu

    2018-03-01

    Wide-field microscopy is commonly used for sample observations in biological research and medical diagnosis. However, the tilting error induced by the oblique location of the image recorder or the sample, as well as the inclination of the optical path often deteriorates the imaging quality. In order to eliminate the tilting in microscopy, a numerical tilting compensation technique based on wavefront sensing using transport of intensity equation method is proposed in this paper. Both the provided numerical simulations and practical experiments prove that the proposed technique not only accurately determines the tilting angle with simple setup and procedures, but also compensates the tilting error for imaging quality improvement even in the large tilting cases. Considering its simple systems and operations, as well as image quality improvement capability, it is believed the proposed method can be applied for tilting compensation in the optical microscopy.

  4. Effectiveness of Bed Bug Pesticides

    Science.gov (United States)

    Before EPA allows a bed bug claim on a label, the product must be supported by data showing it will kill bed bugs when applied according to the label. Also consider factors such as extent of infestation, site preparation, and insect life stages.

  5. Intrasellar Symptomatic Salivary Gland Rest

    Directory of Open Access Journals (Sweden)

    Chih-Hao Chen

    2007-05-01

    Full Text Available Ectopic salivary gland tissue in sellar turcica is frequently observed in microscopic examination at autopsy. This tissue is considered clinically silent. Only 2 symptomatic cases have been previously reported. Here we report a 28-year-old woman presenting with galactorrhea and hyperprolactinemia. Magnetic resonance imaging revealed a 6×5-mm nodule in the posterior aspect of the pituitary gland. This nodule showed isointensity on T1- and T2-weighted images and less enhancement on post-contrast T1-weighted images. Transsphenoidal exploration revealed a cystic lesion within the pituitary gland, which consisted of a grayish gelatinous content. The pathologic examination confirmed the diagnosis of salivary gland rest.

  6. Birth and demise of a Middle Jurassic isolated shallow-marine carbonate platform on a tilted fault block: Example from the Southern Iberian continental palaeomargin

    Science.gov (United States)

    Navarro, V.; Ruiz-Ortiz, P. A.; Molina, J. M.

    2012-08-01

    Subbetic Middle Jurassic oolitic limestones of the Jabalcuz Formation crop out in San Cristóbal hill, near Jaén city (Andalucía, Spain), between hemipelagic limestone and marl successions. The Jabalcuz limestones range in facies from calcareous breccias and micritic limestones to white cross-bedded oolitic limestones. Recent erosion has exhumed a Jurassic isolated shallow-water carbonate platform on the San Cristóbal hill. This shallow platform developed on a tilted fault block. An almost continuous, laterally extensive outcrop reveals tectono-sedimentary features distinctive of block-tilting in the different margins of the fault block. The studied sections represent various palaeogeographic positions in the ancient shallow-water carbonate platform and basin transition. This exceptional outcrop allows to decipher the triggering mechanisms of the birth, evolution, and drowning of this Jurassic isolated shallow-water carbonate platform. Two shallowing-upward depositional sequences separated by flooding surfaces can be distinguished on two different sides of the fault block. In the southeastern part of the outcrop, proximal sections grade vertically from distal talus fault breccias, with bivalve and serpulid buildup intercalations, to white cross-bedded oolitic limestones defining the lowermost depositional sequence. Upwards, overlying a flooding surface, the second sequence with oolitic limestones prograding over micritic deposits is recorded. In the southwest, oolitic, peloidal, and more distal micritic facies alternate, with notable southeastern progradation of oolitic facies in the upper part of the section, which represents the upper depositional sequence. The top of this second depositional sequence is another flooding surface recorded by the sedimentation of marls with radiolarians from the overlying formation. In the northwestern outcrops, the two depositional sequences are also almost completely preserved and can be differentiated. A 100 m

  7. Misting and fan cooling of the rest area in a dairy barn

    Science.gov (United States)

    Calegari, Ferdinando; Calamari, Luigi; Frazzi, Ermes

    2012-03-01

    This summer study aimed to evaluate the effect on dairy cows, kept in a free stall barn equipped with fans and sprinklers in the feeding area, of the delivery rate of misters in a cooling system in rest areas with different bedding materials. Thirty cows were divided into two homogenous groups according to milk yield and kept in two pens: one had beds with sand (SAMM) while the other had straw (STLM). Each pen was equipped with 2 fans (Ø 70 cm, 0.50 kW) and 2 misters (delivery rate of 11.2 and 22.5 L/h in STLM and SAMM, respectively) in the rest area. Microclimatic parameters, rectal temperature (RT), breathing rate (BR), milk yield, and some milk traits were recorded. Behavioural routines of the cows (standing and lying) were also continuously recorded during the hotter days. During the trial, two mild-moderate heat waves were observed. During these hotter periods, the daily maximum temperature recorded in the rest areas was 28.9 in SAMM and 31.2 in STLM, and the daily maximum THI was 78.2 in SAMM and 81.5 in STLM. In these periods, the cows in SAMM compared with those in STLM showed lower BR ( P sand as bedding materials reduces heat stress and improves cow comfort.

  8. Direct Observation of Heavy-Tailed Storage Times of Bed Load Tracer Particles Causing Anomalous Superdiffusion

    Science.gov (United States)

    Bradley, D. Nathan

    2017-12-01

    A consensus has formed that the step length distribution of fluvial bed load is thin tailed and that the observed anomalous superdiffusion of bed load tracer particles must arise from heavy-tailed resting times. However, heavy-tailed resting times have never been directly observed in the field over multiple floods. Using 9 years of data from a large bed load tracer experiment, I show that the spatial variance of the tracer plume scales faster than linearly with integrated excess stream power, indicating anomalous superdiffusion. The superdiffusion is caused by a heavy-tailed distribution of observed storage times that is fit with a truncated Pareto distribution with a tail parameter that is predicted by anomalous diffusion theory. The heavy-tailed distribution of storage times causes the tracer virtual velocity to slow over time, indicated by a sublinear increase in the mean displacement that is predicted by the storage time distribution tail parameter.

  9. Protecting Your Home from Bed Bugs

    Science.gov (United States)

    ... your home: Inspect the luggage rack in your hotel room for bed bugs. Check secondhand furniture, beds, ... with Bed Bug Problems Discover. Accessibility EPA Administrator Budget & Performance Contracting Grants January 19, 2017 Web Snapshot ...

  10. Study of a Car Body Tilting System Using a Variable Link Mechanism: Fundamental Characteristics of Pendulum Motion and Strategy for Perfect Tilting

    Science.gov (United States)

    Yoshida, Hidehisa; Nagai, Masao

    This paper analyzes the fundamental dynamic characteristics of a tilting railway vehicle using a variable link mechanism for compensating both the lateral acceleration experienced by passengers and the wheel load imbalance between the inner and outer rails. The geometric relations between the center of rotation, the center of gravity, and the positions of all four links of the tilting system are analyzed. Then, equations of the pendulum motions of the railway vehicle body with a four-link mechanism are derived. A theoretically discussion is given on the geometrical shapes employed in the link mechanism that can simultaneously provide zero lateral acceleration and zero wheel load fluctuation. Then, the perfect tilting condition, which is the control target of the feedforward tilting control, is derived from the linear equation of tilting motion.

  11. Gas fluidized bed reactor

    International Nuclear Information System (INIS)

    Bernardelli, H. da C.

    1976-03-01

    The equations of motion for both gas and particles in a gas fluidised system are stablished through general assumptions which are generally accepted on physical grounds. The resulting model is used to study the velocity fields of each phase in the case of an isolated bubble rising close to the flat distributor plate. A well posed problem results for the solution of Laplace's equation of the potential flow of the particles when consideration is given to the presence of the distributor as a boundary condition. The corresponding stream functions are also obtained which enable the drawing of the motion patterns using numerical techniques. The following two dimensional cases are analysed: S/b=1; S/b=1,5; S/b=2,5; S/b=5 and the limiting case S/b→αinfinite. The results for the interphase exchange between bubbles and particulate phases are applied to a gas fluidised bed reactor and its effect on the chemical conversion is studied for the simplest cases of piston flow and perfect mixing in the particulate phase [pt

  12. Chaotic hydrodynamics of fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Van der Stappen, M.L.M. [Unit Process and Systems Engineering, Advanced Manufacturing Technology Group, Unilever Research Laboratorium, Vlaardingen (Netherlands)

    1996-12-31

    The major goals of this thesis are: (1) to develop and evaluate an analysis method based on techniques from non-linear chaos theory to characterize the nonlinear hydrodynamics of gas-solids fluidized beds quantitatively; and (2) to determine the dependence of the chaotic invariants on the operating conditions and investigate how the chaos analysis method can be profitably applied to improve scale-up and design of gas-solids fluidized bed reactors. Chaos theory is introduced in chapter 2 with emphasis on analysis techniques for (experimental) time series, known from literature at the start of this work (1990-1991). In chapter 3, the testing of existing and newly developed techniques on both model and fluidized bed data is described. This leads to the development of the chaos analysis method to analyze measured pressure fluctuations time series of a fluidized bed. Following, in chapter 4, this method is tested and all choices for the parameters are evaluated. The influence of the experimental parameters and external disturbances on the measurements and analysis results is discussed and quantified. The result is a chaos measurement and analysis protocol, which is further used in this work. In chapter 5, the applications to fluidized beds are discussed. It is shown that the entropy is a good measure for the characterization of the dynamical behavior of gas-solids bubbling/slugging fluidized beds. Entropy is applied to characterize the influence of the operating conditions, to assess regime transitions and to analyze dimensionless similar beds of different scale. Quantitative design correlations that relate entropy to the operating parameters (including the bed diameter) are described. Finally, it is discussed how the results of this work might be used in scaling up the chaotic dynamics of fluidized beds. The overall conclusions and outlook from this work are presented in chapter 6. 182 refs.

  13. Automatic determination of 3D orientations of fossilized oyster shells from a densely packed Miocene shell bed

    Science.gov (United States)

    Puttonen, Ana; Harzhauser, Mathias; Puttonen, Eetu; Mandic, Oleg; Székely, Balázs; Molnár, Gábor; Pfeifer, Norbert

    2018-02-01

    Shell beds represent a useful source of information on various physical processes that cause the depositional condition. We present an automated method to calculate the 3D orientations of a large number of elongate and platy objects (fossilized oyster shells) on a sedimentary bedding plane, developed to support the interpretation of possible depositional patterns, imbrications, or impact of local faults. The study focusses on more than 1900 fossil oyster shells exposed in a densely packed Miocene shell bed. 3D data were acquired by terrestrial laser scanning on an area of 459 m2 with a resolution of 1 mm. Bivalve shells were manually defined as 3D-point clouds of a digital surface model and stored in an ArcGIS database. An individual shell coordinate system (ISCS) was virtually embedded into each shell and its orientation was determined relative to the coordinate system of the entire, tectonically tilted shell bed. Orientation is described by the rotation angles roll, pitch, and yaw in a Cartesian coordinate system. This method allows an efficient measurement and analysis of the orientation of thousands of specimens and is a major advantage compared to the traditional 2D approach, which measures only the azimuth (yaw) angles. The resulting data can variously be utilized for taphonomic analyses and the reconstruction of prevailing hydrodynamic regimes and depositional environments. For the first time, the influence of possible post-sedimentary vertical displacements can be quantified with high accuracy. Here, the effect of nearby fault lines—present in the reef—was tested on strongly tilted oyster shells, but it was found out that the fault lines did not have a statistically significant effect on the large tilt angles. Aside from the high reproducibility, a further advantage of the method is its non-destructive nature, which is especially suitable for geoparks and protected sites such as the studied shell bed.

  14. Bed retained products in swept fixed bed (SFB) coal hydropyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Mastral, A.M.; Perez-Surio, M.J. [CSIC, Zaragosa (Spain). Inst. de Carboquimica

    1997-12-31

    The hydropyrolysis of a low rank coal in a swept fixed bed (SFB) reactor is carried out by fixing the hydrogen pressure (40 kg/cm{sup 2}), the hydrogen flow (2 l/min) and the residence time (10 min) at increasing temperatures (400 C, 500 C and 600 C) and coal bed heights (h, 1.5h, 2h, 2.5h and 3h). It is shown that the percentages of tars and char directly depend on the coal bed height and that there is not only a quantitative dependence, but also the height of the coal bed is very important and plays a relevant role on the nature of the conversion products. (orig.)

  15. Bed diameter effects and incipient slugging in gas fluidized beds

    International Nuclear Information System (INIS)

    Agarwal, P.K.

    1986-01-01

    The coalescence and growth of bubble swarms formed at the distributor of a fluidized bed gives rise to lateral as well as vertical distributions of bubble properties. However, existing models employ average bubble properties obtained largely from semi-empirical considerations. In a recent Paper, the author developed a bubble growth model based on a population balance approach. Analytical expressions were derived for the bubble characteristic distributions and averages. However, the model, developed for unconstrained growth, did not take into account the effect of the bed diameter and the possibility of slugging. In this Paper, the model is extended to take these aspects into account. A slugging criterion is also developed which is expected to be valid for the regime where incipient slugging depends on the bed height as well as the region where bed height does not significantly affect minimum slugging conditions

  16. Pro REST API development with nodejs

    CERN Document Server

    Doglio, Fernando

    2015-01-01

    Pro REST API Development with Node.js is your guide to managing and understanding the full capabilities of successful REST development. API design is a hot topic in the programming world, but not many resources exist for developers to really understand how you can leverage the advantages. This book will provide a brief background on REST and the tools it provides (well known and not so well known). Understand how there is more to REST than just JSON and URLs. You will then cover and compare the maintained modules currently available in the npm community, including Express, Restify, Vatican,

  17. Impact of bed rest on conduit artery remodeling: effect of exercise countermeasures.

    NARCIS (Netherlands)

    Duijnhoven, N.T.L. van; Green, D.J.; Felsenberg, D.; Belavy, D.L.; Hopman, M.T.E.; Thijssen, D.H.J.

    2010-01-01

    Physical inactivity is a potent stimulus for vascular remodeling, leading to a marked decrease in conduit artery diameter. However, little is known about the impact of physical inactivity on artery wall thickness or wall:lumen ratio or the potential of exercise countermeasures to modify artery wall

  18. +Gz tolerance after 14 days bed rest and the effects of rehydration.

    Science.gov (United States)

    Greenleaf, J. E.; Van Beaumont, W.; Bernauer, E. M.; Haines, R. F.; Sandler, H.; Young, H. L.; Yusken, J. W.

    1972-01-01

    Measurement of the reduction in centrifugation tolerance after two weeks of bedrest with moderate daily exercise, with an attempt to determine if rehydration improves +Gz tolerance. There were significant reductions in +Gz tolerance during bedrest periods at three acceleration levels. Rehydration resulted in a significant increase in tolerance at 2.1G but it did not restore tolerance to control levels. Rehydration did not affect tolerance at 3.2G and 3.8G.

  19. Prostate bed motion may cause geographic miss in post-prostatectomy image-guided intensity-modulated radiotherapy

    International Nuclear Information System (INIS)

    Bell, Linda J.; Cox, Jennifer; Eade, Thomas; Rinks, Marianne; Kneebone, Andrew

    2013-01-01

    There is little data to guide radiation oncologists on appropriate margin selection in the post-prostatectomy setting. The aim of this study was to quantify interfraction variation in motion of the prostate bed to determine these margins. The superior and inferior surgical clips in the prostate bed were tracked on pretreatment cone beam CT images (n=377) for 40 patients who had received post-prostatectomy radiotherapy. Prostate bed motion was calculated for the upper and lower segments by measuring the position of surgical clips located close to midline relative to bony anatomy in the axial (translational) and sagittal (tilt) planes. The frequency of potential geographic misses was calculated for either 1cm or 0.5cm posterior planning target volume margins. The mean magnitude of movement of the prostate bed in the anterior–posterior, superior–inferior and left–right planes, respectively, were as follows: upper portion, 0.50cm, 0.28cm, 0.10cm; lower portion, 0.18cm, 0.18cm, 0.08cm. The random and systematic errors, respectively, of the prostate bed motion in the anterior–posterior, superior–inferior and left–right planes, respectively, were as follows: upper portion, 0.47cm and 0.50cm, 0.28cm and 0.27cm, 0.11cm and 0.11cm; lower portion, 0.17cm and 18cm, 0.17cm and 0.19cm, 0.08cm and 0.10cm. Most geographic misses occurred in the upper prostate bed in the anterior–posterior plane. The median prostate bed tilt was 1.8° (range −23.4° to 42.3°). Variability was seen in all planes for the movement of both surgical clips. The greatest movement occurred in the anterior–posterior plane in the upper prostate bed, which could cause geographic miss of treatment delivery. The variability in the movement of the superior and inferior clips indicates a prostate bed tilt that would be difficult to correct with standard online matching techniques. This creates a strong argument for using anisotropic planning target volume margins in post

  20. Using multiple bed load measurements: Toward the identification of bed dilation and contraction in gravel-bed rivers

    Science.gov (United States)

    Marquis, G. A.; Roy, A. G.

    2012-02-01

    This study examines bed load transport processes in a small gravel-bed river (Béard Creek, Québec) using three complementary methods: bed elevation changes between successive floods, bed activity surveys using tags inserted into the bed, and bed load transport rates from bed load traps. The analysis of 20 flood events capable of mobilizing bed material led to the identification of divergent results among the methods. In particular, bed elevation changes were not consistent with the bed activity surveys. In many cases, bed elevation changes were significant (1 to 2 times the D50) even if the bed surface had not been activated during the flood, leading to the identification of processes of bed dilation and contraction that occurred over 10% to 40% of the bed surface. These dynamics of the river bed prevent accurate derivation of bed load transport rates from topographic changes, especially for low magnitude floods. This paper discusses the mechanisms that could explain the dilation and contraction of particles within the bed and their implications in fluvial dynamics. Bed contraction seems to be the result of the winnowing of the fine sediments under very low gravel transport. Bed dilation seems to occur on patches of the bed at the threshold of motion where various processes such as fine sediment infiltration lead to the maintenance of a larger sediment framework volume. Both processes are also influenced by flood history and the initial local bed state and in turn may have a significant impact on sediment transport and morphological changes in gravel-bed rivers.

  1. Resting state fMRI: A review on methods in resting state connectivity analysis and resting state networks.

    Science.gov (United States)

    Smitha, K A; Akhil Raja, K; Arun, K M; Rajesh, P G; Thomas, Bejoy; Kapilamoorthy, T R; Kesavadas, Chandrasekharan

    2017-08-01

    The inquisitiveness about what happens in the brain has been there since the beginning of humankind. Functional magnetic resonance imaging is a prominent tool which helps in the non-invasive examination, localisation as well as lateralisation of brain functions such as language, memory, etc. In recent years, there is an apparent shift in the focus of neuroscience research to studies dealing with a brain at 'resting state'. Here the spotlight is on the intrinsic activity within the brain, in the absence of any sensory or cognitive stimulus. The analyses of functional brain connectivity in the state of rest have revealed different resting state networks, which depict specific functions and varied spatial topology. However, different statistical methods have been introduced to study resting state functional magnetic resonance imaging connectivity, yet producing consistent results. In this article, we introduce the concept of resting state functional magnetic resonance imaging in detail, then discuss three most widely used methods for analysis, describe a few of the resting state networks featuring the brain regions, associated cognitive functions and clinical applications of resting state functional magnetic resonance imaging. This review aims to highlight the utility and importance of studying resting state functional magnetic resonance imaging connectivity, underlining its complementary nature to the task-based functional magnetic resonance imaging.

  2. Tilting mode in rigidly rotating field-reversed configurations

    International Nuclear Information System (INIS)

    Clemente, R.A.; Milovich, J.L.

    1983-01-01

    The tilting-mode stability of field-reversed configurations is analyzed taking into account plasma rotational effects that had not been included in previous theoretical treatments. It is shown that for a rigidly rotating plasma in stationary equilibrium, stability can be attained if the plasma rotational energy is of the same order as the thermal energy. Since presently available values of the rotational velocities are quite lower than required by the stabilization mechanism considered here, the contribution of this effect to the overall stability of the mode does not appear to be significant

  3. Tilt-tuned etalon locking for tunable laser stabilization.

    Science.gov (United States)

    Gibson, Bradley M; McCall, Benjamin J

    2015-06-15

    Locking to a fringe of a tilt-tuned etalon provides a simple, inexpensive method for stabilizing tunable lasers. Here, we describe the use of such a system to stabilize an external-cavity quantum cascade laser; the locked laser has an Allan deviation of approximately 1 MHz over a one-second integration period, and has a single-scan tuning range of approximately 0.4  cm(-1). The system is robust, with minimal alignment requirements and automated lock acquisition, and can be easily adapted to different wavelength regions or more stringent stability requirements with minor alterations.

  4. Interpretation and quality of the tilted axis cranking approximation

    International Nuclear Information System (INIS)

    Frauendorf, S.; Meng, J.

    1996-06-01

    Comparing with the exact solutions of the model system of one and two particles coupled to an axial rotor, the quality of the semi classical tilted axis cranking approximation is investigated. Extensive comparisons of the energies and M1 and E2 transition probabilities are carried out for the lowest bands. Very good agreement is found, except near band crossings. Various recipes to take into account finite K within the frame of the usual principal axis cranking are included into the comparison. A set of rules is suggested that permits to construct the excited bands from the cranking configurations, avoiding spurious states. (orig.)

  5. A computer simulation study of tilted smectic mesophases

    International Nuclear Information System (INIS)

    Withers, I.M.

    2000-05-01

    Results are presented from a series of simulations undertaken to determine the effect of a novel form of molecular biaxiality upon the phase behaviour of the well established Gay-Berne (GB) liquid crystal model. Firstly, the simulation of a bulk system interacting via the Internally-Rotated Gay Berne (IRGB) potential, which offers a single-site representation of a molecule rigidly constrained into a zig-zag conformation, is presented. The results of simulations performed for systems of IRGB particles with an aspect ratio of 3:1 confirm that the introduction of biaxiality into the model results in the destabilisation of the orientationally ordered phases. For particles with a sufficiently pronounced zig-zag conformation, this results in the complete destabilisation of the smectic A phase and the smectic B phase being replaced by the tilted smectic J phase. Following these observations, the effect upon the phase behaviour of increasing molecular elongation is also considered, with an increase in the aspect ratio from 3:1 to 4:1 resulting in the nematic and smectic J phases being replaced by smectic A and smectic G phases respectively. Secondly, a version of the IRGB potential modified to include a degree of molecular flexibility is considered. Results obtained from bulk systems interacting via the flexible IRGB for 3:1 and 4:1 molecules show that the introduction of flexibility results in the destabilisation of the smectic A phase and the stabilisation of the nematic and tilted hexatic phases. Finally, the effect upon the phase behaviour of the rigid IRGB model of the inclusion of a longitudinal linear quadrupole is examined. These results show that increasing quadrupole moment results in the destabilisation of the tilted hexatic phase, although the biaxial order parameter is increased with increasing quadrupole moment. There is no clear correlation between quadrupole magnitude and the other observed phase transitions, with the nematic and smectic A phases being

  6. Instability of nuclear wobbling motion and tilted axis rotation

    International Nuclear Information System (INIS)

    Matsuzaki, Masayuki; Ohtsubo, Shin-Ichi

    2004-01-01

    We study a possible correspondence between the softening of the wobbling mode and the 'phase transition' of the one-dimensionally rotating mean field to a three-dimensionally rotating one by comparing the properties of the wobbling mode obtained by the one-dimensional cranking model + random phase approximation with the total Routhian surface obtained by the three-dimensional tilted-axis cranking model. The potential surface for the observed wobbling mode excited on the triaxial superdeformed states in 163 Lu is also analyzed

  7. Tilted bending magnet for SPS target area TCC2

    CERN Multimedia

    CERN PhotoLab

    1976-01-01

    A slow-extracted proton beam from the SPS goes to the underground target zone TCC2. The part of the primary beam which traverses target T4 is recuperated and transported over some 800 m, for further use in the North Area High Intensity facility (NAHIF). The curved and sloped trajectory required 4 of the bending magnets to be tilted. Here we see one of them being attended by Gilbert Françon in hall 867, ready for installation in TCC2.

  8. Flow tilt angles near forest edges - Part 2: Lidar anemometry

    DEFF Research Database (Denmark)

    Dellwik, Ebba; Mann, Jakob; Bingöl, Ferhat

    2010-01-01

    to sonic anemometry; there is no flow distortion caused by the instrument itself, there are no temperature effects and the instrument misalignment can be corrected for by assuming zero tilt angle at high altitudes. Contrary to mast-based instruments, the lidar measures the wind field with the exact same...... alignment error at a multitude of heights. Disadvantages with estimating vertical velocities from a lidar compared to mast-based measurements are potentially slightly increased levels of statistical errors due to limited sampling time, because the sampling is disjunct, and a requirement for homogeneous flow...

  9. Better backs by better beds?

    DEFF Research Database (Denmark)

    Bergholdt, Kim; Fabricius, Rasmus N; Bendix, Tom

    2008-01-01

    mattresses have a positive effect on LBP, and especially a hard mattress is commonly believed to have a positive effect. METHODS: One hundred sixty CLBP patients were randomized to 1 of 3 groups, having a mattress/bed mounted in their sleeping room for 1 month. The beds were: (1) waterbed (Akva), (2) body......-conforming foam mattress (Tempur), and (3) a hard mattress (Innovation Futon). At baseline and after 4 weeks, a blinded observer interviewed the patients on LBP levels (0-10), daily function (activities of daily living, 0-30), and on the amount of sleeping hours/night. RESULTS: Because of dropout of 19 patients...... using the probably most relevant "worst case" data. There were no relevant difference between the effects of the water bed and the foam bed. CONCLUSION: The Waterbed and foam mattress' did influence back symptoms, function and sleep more positively as apposed to the hard mattress, but the differences...

  10. Top Ten Bed Bug Tips

    Science.gov (United States)

    ... Directory Planning, Budget and Results Jobs and Internships Headquarters Offices Regional Offices Labs and Research Centers Bed ... you hire an expert, be sure it’s a company with a good reputation and request that it ...

  11. Torsion testing of bed joints

    DEFF Research Database (Denmark)

    Hansen, Klavs Feilberg; Pedersen, Carsten Mørk

    2008-01-01

    This paper describes a simple test method for determining the torsion strength of a single bed joint between two bricks and presents results from testing using this test method. The setup for the torsion test is well defined, require minimal preparation of the test specimen and the test can...... be carried out directly in a normal testing machine. The torsion strength is believed to be the most important parameter in out-of-plane resistance of masonry walls subjected to bending about an axis perpendicular to the bed joints. The paper also contains a few test results from bending of small walls about...... an axis perpendicular to the bed joints, which indicate the close connection between these results and results from torsion tests. These characteristics make the torsion strength well suited to act as substitute parameter for the bending strength of masonry about an axis perpendicular to the bed joints....

  12. Sea bed mapping and inspection

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    The conference has 24 presentations on the topics: Sea bed mapping, inspection, positioning, hydrography, marine archaeology, remote operation vehicles and computerized simulation technologies, oil field activities and plans, technological experiences and problems. (tk)

  13. Fluid-bed methane proposed

    Energy Technology Data Exchange (ETDEWEB)

    1981-05-01

    The first full scale plant for the production of methane from organic waste could be built in the next few years believes M.J. Nyns of the University of Louvain, Belgium, utilizing either expanded bed or fluidised bed systems, with more than one stage, in a continuous flow arrangement. Up to 8.0 m cubed gas/m cubed digester/day could be produced with residence times reduced to 34 hours.

  14. Dispersion of Bed Load Particles

    OpenAIRE

    SAWAI, Kenji

    1987-01-01

    The motion of bed load particles is so irregular that they disperse remarkably with time.In this study, some flume tests using painted tracer particles were carried out, in which thedispersive property of tracers changed variously with sediment feed rate.In analysing this process, a stochastic simulation model is proposed where it is discussedabout the degree of exposure of individual particle near the bed surface and about the variationof its pick up rate. The exponential distribution of ste...

  15. Head tilt produced by hemilabyrinthectomy does not depend on the direct vestibulospinal tracts.

    Science.gov (United States)

    Fukushima, K; Fukushima, J; Kato, M

    1988-01-01

    Head tilt is one of the most characteristic and enduring symptoms produced by hemilabyrinthectomy and is compensated by the central nervous system with time. In order to study the central mechanisms of compensation of the head tilt, it is first necessary to understand how it is produced. However, its mechanism remains unknown. Experiments were performed in cats to examine whether the direct vestibulocollic pathways are responsible for the head tilt, as suggested by some authors. Hemilabyrinthectomies produced a characteristic head tilt in cats in which the medial and/or one lateral vestibulospinal tracts (VSTs) had been interrupted. The lesions of the medial VST did not influence the preexisting head tilt produced by hemilabyrinthectomies. These results suggest that the head tilt produced by hemilabyrinthectomies does not depend on the activity of the VSTs.

  16. Cognitive Rest: An Integrated Literature Review

    Science.gov (United States)

    Schneider, Kathleen H.

    2016-01-01

    Cognitive rest has been suggested as a treatment for school athletes who have sustained a concussion, but the concept has rarely been defined. The purpose of this article is to provide a comprehensive definition of cognitive rest, based on an integrative literature review. The method of synthesis was guided by Avant and Walker's concept analysis…

  17. Resting state EEG correlates of memory consolidation.

    Science.gov (United States)

    Brokaw, Kate; Tishler, Ward; Manceor, Stephanie; Hamilton, Kelly; Gaulden, Andrew; Parr, Elaine; Wamsley, Erin J

    2016-04-01

    Numerous studies demonstrate that post-training sleep benefits human memory. At the same time, emerging data suggest that other resting states may similarly facilitate consolidation. In order to identify the conditions under which non-sleep resting states benefit memory, we conducted an EEG (electroencephalographic) study of verbal memory retention across 15min of eyes-closed rest. Participants (n=26) listened to a short story and then either rested with their eyes closed, or else completed a distractor task for 15min. A delayed recall test was administered immediately following the rest period. We found, first, that quiet rest enhanced memory for the short story. Improved memory was associated with a particular EEG signature of increased slow oscillatory activity (rest can facilitate memory, and that this may occur via an active process of consolidation supported by slow oscillatory EEG activity and characterized by decreased attention to the external environment. Slow oscillatory EEG rhythms are proposed to facilitate memory consolidation during sleep by promoting hippocampal-cortical communication. Our findings suggest that EEG slow oscillations could play a significant role in memory consolidation during other resting states as well. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Research on Calculation of the IOL Tilt and Decentration Based on Surface Fitting

    OpenAIRE

    Li, Lin; Wang, Ke; Yan, Yan; Song, Xudong; Liu, Zhicheng

    2013-01-01

    The tilt and decentration of intraocular lens (IOL) result in defocussing, astigmatism, and wavefront aberration after operation. The objective is to give a method to estimate the tilt and decentration of IOL more accurately. Based on AS-OCT images of twelve eyes from eight cases with subluxation lens after operation, we fitted spherical equation to the data obtained from the images of the anterior and posterior surfaces of the IOL. By the established relationship between IOL tilt (decentrati...

  19. The effects of superimposed tilt and lower body negative pressure on anterior and posterior cerebral circulations

    OpenAIRE

    Tymko, Michael M.; Rickards, Caroline A.; Skow, Rachel J.; Ingram?Cotton, Nathan C.; Howatt, Michael K.; Day, Trevor A.

    2016-01-01

    Abstract Steady?state tilt has no effect on cerebrovascular reactivity to increases in the partial pressure of end?tidal carbon dioxide (PETCO 2). However, the anterior and posterior cerebral circulations may respond differently to a variety of stimuli that alter central blood volume, including lower body negative pressure (LBNP). Little is known about the superimposed effects of head?up tilt (HUT; decreased central blood volume and intracranial pressure) and head?down tilt (HDT; increased ce...

  20. Spontaneous tilting after placement of the gunther-tulip inferior vena caval filter: a case report

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Tae Seok; Cha, In Ho; Seol, Hae Young; Park, Cheol Min [Guro Hospital, Korea University College of Medicine, Seoul (Korea, Republic of)

    2006-10-15

    Tilting of a deployed filter in the inferior vena cava (IVC) is a particular kind of periprocedural complication and this can reduce the filter's clot-trapping ability and increase the occlusion of the IVC at a later period. The authors report here on a case of spontaneous tilting of an inferior vena caval filter that was associated with thrombosis in the IVC within 2 weeks of the initially successful placement of the filter without tilting.

  1. Spontaneous tilting after placement of the gunther-tulip inferior vena caval filter: a case report

    International Nuclear Information System (INIS)

    Seo, Tae Seok; Cha, In Ho; Seol, Hae Young; Park, Cheol Min

    2006-01-01

    Tilting of a deployed filter in the inferior vena cava (IVC) is a particular kind of periprocedural complication and this can reduce the filter's clot-trapping ability and increase the occlusion of the IVC at a later period. The authors report here on a case of spontaneous tilting of an inferior vena caval filter that was associated with thrombosis in the IVC within 2 weeks of the initially successful placement of the filter without tilting

  2. An efficient wave extrapolation method for anisotropic media with tilt

    KAUST Repository

    Waheed, Umair bin

    2015-03-23

    Wavefield extrapolation operators for elliptically anisotropic media offer significant cost reduction compared with that for the transversely isotropic case, particularly when the axis of symmetry exhibits tilt (from the vertical). However, elliptical anisotropy does not provide accurate wavefield representation or imaging for transversely isotropic media. Therefore, we propose effective elliptically anisotropic models that correctly capture the kinematic behaviour of wavefields for transversely isotropic media. Specifically, we compute source-dependent effective velocities for the elliptic medium using kinematic high-frequency representation of the transversely isotropic wavefield. The effective model allows us to use cheaper elliptic wave extrapolation operators. Despite the fact that the effective models are obtained by matching kinematics using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy trade-off for wavefield computations in transversely isotropic media, particularly for media of low to moderate complexity. In addition, the wavefield solution is free from shear-wave artefacts as opposed to the conventional finite-difference-based transversely isotropic wave extrapolation scheme. We demonstrate these assertions through numerical tests on synthetic tilted transversely isotropic models.

  3. Evaluation of the Thermal Effects in Tilting Pad Bearing

    Directory of Open Access Journals (Sweden)

    G. B. Daniel

    2013-01-01

    Full Text Available The analysis of thermal effects is of expressive importance in the context of rotordynamics to evaluate the behavior of hydrodynamic bearings because these effects can influence their dynamic characteristics under specific operational conditions. For this reason, a thermohydrodynamic model is developed in this work, in which the pressure distribution in the oil film and the temperature distribution are calculated together. From the pressure distribution, the velocity distribution field is determined, as well as the viscous dissipation, and consequently, the temperature distribution. The finite volume method is applied to solve the Reynolds equation and the energy equation in the thermohydrodynamic model (THD. The results show that the temperature is higher as the rotational speed increases due to the shear rate of the oil film. The maximum temperature in the bearing occurs in the overloaded pad, near the outlet boundary. The experimental tests were performed in a tilting pad journal bearing operating in a steam turbine to validate the model. The comparison between the experimental and numerical results provides a good correlation. The thermohydrodynamic lubrication developed in this assignment is promising to consistently evaluate the behavior of the tilting pad journal bearing operating in relatively high rotational speeds.

  4. Tidal tilts observations in the Gran Sasso underground laboratory

    International Nuclear Information System (INIS)

    Iafolla, V.; Nozzoli, S.; Milyukov, V.

    2001-01-01

    A new tilt meter, based on the technology for building a space-borne high-sensitivity accelerometer and manufactured at IFSI/CNR, has a been operating during several years in the INFN Gran Sasso underground laboratory. The results of the analysis of a three-year data set, processed with the program package ETERNA, to estimate earth tidal parameters are reported. For the best series of data (1998) tide measurement accuracies are: 0.5-1% for the M 2 (lunar principal) amplitude and 3-4% for the O 1 (lunar declination) amplitude. The tilt meter installed at a depth of 1400 m shows no clear evidence of meteorological effects. Observed tidal parameters are compared with theoretical tidal parameters predicted for a non-hydrostatic inelastic Earth model and demonstrate good agreement for the M 2 component. Due to the high accuracy of the tidal components prediction (better than 1%) tidal measurements were used to estimate the long-term stability of the instrument response

  5. Effective ellipsoidal models for wavefield extrapolation in tilted orthorhombic media

    KAUST Repository

    Waheed, Umair Bin

    2016-04-22

    Wavefield computations using the ellipsoidally anisotropic extrapolation operator offer significant cost reduction compared to that for the orthorhombic case, especially when the symmetry planes are tilted and/or rotated. However, ellipsoidal anisotropy does not provide accurate wavefield representation or imaging for media of orthorhombic symmetry. Therefore, we propose the use of ‘effective ellipsoidally anisotropic’ models that correctly capture the kinematic behaviour of wavefields for tilted orthorhombic (TOR) media. We compute effective velocities for the ellipsoidally anisotropic medium using kinematic high-frequency representation of the TOR wavefield, obtained by solving the TOR eikonal equation. The effective model allows us to use the cheaper ellipsoidally anisotropic wave extrapolation operators. Although the effective models are obtained by kinematic matching using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including frequency dependency and caustics, if present, with reasonable accuracy. The proposed methodology offers a much better cost versus accuracy trade-off for wavefield computations in TOR media, particularly for media of low to moderate anisotropic strength. Furthermore, the computed wavefield solution is free from shear-wave artefacts as opposed to the conventional finite-difference based TOR wave extrapolation scheme. We demonstrate applicability and usefulness of our formulation through numerical tests on synthetic TOR models. © 2016 Institute of Geophysics of the ASCR, v.v.i

  6. An efficient wave extrapolation method for anisotropic media with tilt

    KAUST Repository

    Waheed, Umair bin; Alkhalifah, Tariq Ali

    2015-01-01

    Wavefield extrapolation operators for elliptically anisotropic media offer significant cost reduction compared with that for the transversely isotropic case, particularly when the axis of symmetry exhibits tilt (from the vertical). However, elliptical anisotropy does not provide accurate wavefield representation or imaging for transversely isotropic media. Therefore, we propose effective elliptically anisotropic models that correctly capture the kinematic behaviour of wavefields for transversely isotropic media. Specifically, we compute source-dependent effective velocities for the elliptic medium using kinematic high-frequency representation of the transversely isotropic wavefield. The effective model allows us to use cheaper elliptic wave extrapolation operators. Despite the fact that the effective models are obtained by matching kinematics using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy trade-off for wavefield computations in transversely isotropic media, particularly for media of low to moderate complexity. In addition, the wavefield solution is free from shear-wave artefacts as opposed to the conventional finite-difference-based transversely isotropic wave extrapolation scheme. We demonstrate these assertions through numerical tests on synthetic tilted transversely isotropic models.

  7. Clinical applications of resting state functional connectivity

    Directory of Open Access Journals (Sweden)

    Michael D Fox

    2010-06-01

    Full Text Available During resting conditions the brain remains functionally and metabolically active. One manifestation of this activity that has become an important research tool is spontaneous fluctuations in the blood oxygen level dependent (BOLD signal of fMRI. The identification of correlation patterns in these spontaneous fluctuations has been termed resting state functional connectivity (fcMRI and has the potential to greatly increase the translation of fMRI into clinical care. In this article we review the advantages of the resting state signal for clinical applications including detailed discussion of signal to noise considerations. We include guidelines for performing resting state research on clinical populations, outline the different areas for clinical application, and identify important barriers to be addressed to facilitate the translation of resting state fcMRI into the clinical realm.

  8. Comparative analysis of diffused solar radiation models for optimum tilt angle determination for Indian locations

    International Nuclear Information System (INIS)

    Yadav, P.; Chandel, S.S.

    2014-01-01

    Tilt angle and orientation greatly are influenced on the performance of the solar photo voltaic panels. The tilt angle of solar photovoltaic panels is one of the important parameters for the optimum sizing of solar photovoltaic systems. This paper analyses six different isotropic and anisotropic diffused solar radiation models for optimum tilt angle determination. The predicted optimum tilt angles are compared with the experimentally measured values for summer season under outdoor conditions. The Liu and Jordan model is found to exhibit t lowest error as compared to other models for the location. (author)

  9. Comparison of optimum tilt angles of solar collectors determined at yearly, seasonal and monthly levels

    International Nuclear Information System (INIS)

    Despotovic, Milan; Nedic, Vladimir

    2015-01-01

    Highlights: • Optimum yearly, biannual, seasonal, monthly, and daily tilt angles were found. • Energy collected per square meter is compared for ten different scenarios. • Four seasonal scenarios and two biannual scenarios were considered. • It is sufficient to adjust tilt angles only twice per year. - Abstract: The amount of energy that is transformed in solar collector depends on its tilt angle with respect to horizontal plane and orientation of the collector. In this article the optimum tilt angle of solar collectors for Belgrade, which is located at the latitude of 44°47′N is determined. The optimum tilt angle was found by searching for the values for which the solar radiation on the collector surface is maximum for a particular day or a specific period. In that manner the yearly, biannual, seasonal, monthly, fortnightly, and daily optimum tilt angles are determined. Annually collected energy per square meter of tilted surface is compared for ten different scenarios. In addition, these optimum tilt angles are used to calculate the amount of energy on the surface of PV panels that could be installed at the roof of the building. The results show that for observed case study placing the panels at yearly, seasonal and monthly optimum tilt angles, would yield increasing yearly amount of collected energy by factor of 5.98%, 13.55%, and 15.42% respectively compared to energy that could be collected by putting the panels at current roofs’ surface angles

  10. NUMERICAL SIMULATIONS OF NATURALLY TILTED, RETROGRADELY PRECESSING, NODAL SUPERHUMPING ACCRETION DISKS

    International Nuclear Information System (INIS)

    Montgomery, M. M.

    2012-01-01

    Accretion disks around black hole, neutron star, and white dwarf systems are thought to sometimes tilt, retrogradely precess, and produce hump-shaped modulations in light curves that have a period shorter than the orbital period. Although artificially rotating numerically simulated accretion disks out of the orbital plane and around the line of nodes generate these short-period superhumps and retrograde precession of the disk, no numerical code to date has been shown to produce a disk tilt naturally. In this work, we report the first naturally tilted disk in non-magnetic cataclysmic variables using three-dimensional smoothed particle hydrodynamics. Our simulations show that after many hundreds of orbital periods, the disk has tilted on its own and this disk tilt is without the aid of radiation sources or magnetic fields. As the system orbits, the accretion stream strikes the bright spot (which is on the rim of the tilted disk) and flows over and under the disk on different flow paths. These different flow paths suggest the lift force as a source to disk tilt. Our results confirm the disk shape, disk structure, and negative superhump period and support the source to disk tilt, source to retrograde precession, and location associated with X-ray and He II emission from the disk as suggested in previous works. Our results identify the fundamental negative superhump frequency as the indicator of disk tilt around the line of nodes.

  11. Effects of external feedback about body tilt: Influence on the Subjective Proprioceptive Horizon.

    Science.gov (United States)

    Bringoux, L; Bourdin, C; Nougier, V; Raphel, C

    2006-11-06

    The present study investigated a cognitive aspect upon spatial perception, namely the impact of a true or false verbal feedback (FB) about the magnitude of body tilt on Subjective Proprioceptive Horizon (SPH) estimates. Subjects were asked to set their extended arm normal to gravity for different pitch body tilts up to 9 degrees . True FB were provided at all body tilt angles, whereas false FB were provided only at 6 degrees backward and 6 degrees forward body tilts for half of the trials. Our data confirmed previous results about the egocentric influence of body tilt itself upon SPH: estimates were linearly lowered with forward tilts and elevated with backward tilts. In addition, results showed a significant effect of the nature of the external FB provided to the subjects. When subjects received a false FB inducing a 3 degrees forward bias relative to physical body tilt, they set their SPH consequently higher than when they received a false FB inducing a 3 degrees backward bias. These findings clearly indicated that false cognitive information about body tilt might significantly modify the judgement of a geocentric direction of space, such as the SPH. This may have deleterious repercussions in aeronautics when pilots have to localize external objects relative to earth-based directions in darkened environments.

  12. Development of a tilting system for electric multiple unit to speed up on conventional lines

    International Nuclear Information System (INIS)

    Seo, Sung Il; Kim, Nam Po; Lee, Soo Gil; Kim, Seok Won

    2008-01-01

    An advanced tilting system for KTT (Korean Tilting Train) was developed and a performance test of the system has been completed. KTT has been constructed to speed up and promise a significant enhancement in service quality on a conventional line. KTT is an electric multiple unit composed of 6 cars running at the design speed of 200 km/h. The tilting system is the core technology of KTT and combined with the conventional bogie system. It has a self-steering mechanism and a swing link. The self-steering mechanism of Z-bar type is free to rotate on the curve and stable to run on a straight line. The swing link mechanism of the bolster enables the carbody to tilt up to 8 .deg.. A tilting control system detects a curve with sensors and commands the electro-mechanical actuators to move the bolster through the computer network system. GPS collaborates with the tilting system to perceive the curve previously and enables gradual tilting so as not to violate passenger comfort. The performance of the tilting system has been verified by a trial test running of KTT on a commercial conventional line. The tilting system is ready for commercial use

  13. Research on Calculation of the IOL Tilt and Decentration Based on Surface Fitting

    Directory of Open Access Journals (Sweden)

    Lin Li

    2013-01-01

    Full Text Available The tilt and decentration of intraocular lens (IOL result in defocussing, astigmatism, and wavefront aberration after operation. The objective is to give a method to estimate the tilt and decentration of IOL more accurately. Based on AS-OCT images of twelve eyes from eight cases with subluxation lens after operation, we fitted spherical equation to the data obtained from the images of the anterior and posterior surfaces of the IOL. By the established relationship between IOL tilt (decentration and the scanned angle, at which a piece of AS-OCT image was taken by the instrument, the IOL tilt and decentration were calculated. IOL tilt angle and decentration of each subject were given. Moreover, the horizontal and vertical tilt was also obtained. Accordingly, the possible errors of IOL tilt and decentration existed in the method employed by AS-OCT instrument. Based on 6–12 pieces of AS-OCT images at different directions, the tilt angle and decentration values were shown, respectively. The method of the surface fitting to the IOL surface can accurately analyze the IOL’s location, and six pieces of AS-OCT images at three pairs symmetrical directions are enough to get tilt angle and decentration value of IOL more precisely.

  14. Research on calculation of the IOL tilt and decentration based on surface fitting.

    Science.gov (United States)

    Li, Lin; Wang, Ke; Yan, Yan; Song, Xudong; Liu, Zhicheng

    2013-01-01

    The tilt and decentration of intraocular lens (IOL) result in defocussing, astigmatism, and wavefront aberration after operation. The objective is to give a method to estimate the tilt and decentration of IOL more accurately. Based on AS-OCT images of twelve eyes from eight cases with subluxation lens after operation, we fitted spherical equation to the data obtained from the images of the anterior and posterior surfaces of the IOL. By the established relationship between IOL tilt (decentration) and the scanned angle, at which a piece of AS-OCT image was taken by the instrument, the IOL tilt and decentration were calculated. IOL tilt angle and decentration of each subject were given. Moreover, the horizontal and vertical tilt was also obtained. Accordingly, the possible errors of IOL tilt and decentration existed in the method employed by AS-OCT instrument. Based on 6-12 pieces of AS-OCT images at different directions, the tilt angle and decentration values were shown, respectively. The method of the surface fitting to the IOL surface can accurately analyze the IOL's location, and six pieces of AS-OCT images at three pairs symmetrical directions are enough to get tilt angle and decentration value of IOL more precisely.

  15. Influence of tilt training on activation of the autonomic nervous system in patients with vasovagal syncope.

    Science.gov (United States)

    Gajek, Jacek; Zyśko, Dorota; Halawa, Bogumił; Mazurek, Walentyna

    2006-04-01

    Tilt training is a new treatment for vasovagal syncope. Its therapeutic efficacy is thought to be the result of the desensitization of cardiopulmonary receptors, but it could be the influence of the tilt training on the activation of the autonomic nervous system as well. The study group consisted of 24 vasovagal patients (17 women and 7 men) aged 32.5 +/- 11.8 years. The diagnostic head-up tilt test was performed according to the Italian protocol with nitroglycerin if necessary. The monitoring head-up tilt test was performed according to the Westminster protocol without provocation, after 1 to 3 months of tilt training. Holter ECG recordings for HRV parameters (time and frequency domain) were obtained from selected 2-min intervals before, during and after the diagnostic and monitoring tilt test. The diagnostic test was positive in the passive phase in 6 and after provocation in 18 patients. During the training period no syncope occurred. Analysing the HRV parameters we demonstrated the following findings: I. mRR decreases immediately after assumption of a vertical position in both tests (diagnostic and monitoring) but in the diagnostic test its further decrease occurs earlier than in the monitoring test; 2. the absolute power of the HF component is greater in the early phase of tilt after tilt training than in the corresponding period in the diagnostic test. After a longer period of tilt training the activation of the sympathetic nervous system in response to the erect position is diminished.

  16. Utility of Recycled Bedding for Laboratory Rodents

    OpenAIRE

    Miyamoto, Toru; Li, Zhixia; Kibushi, Tomomi; Okano, Shinya; Yamasaki, Nakamichi; Kasai, Noriyuki

    2009-01-01

    Animal facilities generate a large amount of used bedding containing excrement as medical waste. We developed a recycling system for used bedding that involves soft hydrothermal processing. In this study, we examined the effects of bedding type on growth, hematologic and serum biochemical values, and organ weights of female and male mice reared on either recycled or fresh bedding from 3 to 33 wk of age. Neither growth nor physiology differed between mice housed on recycled bedding compared wi...

  17. Fluid bed porosity equation for an inverse fluidized bed bioreactor with particles growing biofilm

    International Nuclear Information System (INIS)

    Campos-Diaz, K. E.; Limas-Ballesteros, R.

    2009-01-01

    Fluid Bed Bioreactor performance is strongly affected by bed void fraction or bed porosity fluctuations. Particle size enlargement due to biofilm growth is an important factor that is involved in these variations and until now there are no mathematical equations that consider biofilm growth. In this work a mathematical equation is proposed to calculate bed void fraction in an inverse fluid bed bioreactor. (Author)

  18. Cooling of an internal-heated debris bed with fine particles

    International Nuclear Information System (INIS)

    Yang, Z.L.; Sehgal, B.R.

    2001-01-01

    In this paper, an analytical model on dryout heat flux of ex-vessel debris beds with fines particles under top flooding conditions has been developed. The parametric study is performed on the effect of the stratification of the debris beds on the dryout heat flux. The calculated results show that the stratification configuration of the debris beds with smaller particles and lower porosity layer resting on the top of another layer of the beds has profound effect on the dryout heat flux for the debris beds both with and without a downcomer. The enhancement of the dryout heat flux by the downcomer is significant. The efficiency of the single downcomer on the enhancement of the dryout heat flux is also analyzed. This, in general, agrees well with experimental data. The model is also employed to perform the assessment on the coolability of the ex-vessel debris bed under representative accidental conditions. One conservative case is chosen, and it is found that the downcomer could be efficient measure to cool the debris bed and hence terminate the severe accident. (authors)

  19. Symposium Introduction: Studies of women and men in bed and in space

    Science.gov (United States)

    Hargens, Alan

    INTRODUCTION: Some gender differences in response to microgravity have been noted previously. Furthermore current exercise systems for space flight do not provide loads equal to those on Earth. We hypothesized that supine LBNP treadmill exercise combined with flywheel resistive exercise maintains upright physiologic responses and tissue mass following 30-days and 60-days of head-down tilt (HDT) bed rest (BR). METHODS: For WISE-2005, 16 healthy women (age 25-40 years) underwent a 20-day baseline period, followed by 60-days continuous HDT (-6 degrees) BR and then by recovery for an additional 20-days. Women were assigned to either a control group (CON, n=8) who performed no exercise or to an exercise group (EX, n=8). EX subjects performed a 40-min, variable intensity (40-80 RESULTS: For WISE-2005, post-BR orthostatic tolerance (time to pre-syncope) was signifi- cantly better in the EX group than that in the CON group (p¡ 0.05). On BR day 50, heart rate (HR) was elevated at supine rest for the CON, but not for EX. Moreover, during a supine LBNP stress test at 30 mmHg, the HR increase from Pre-BR to BR day 50 for the EX group was less than that for CON. Heart mass decreased significantly in CON, but increased signifi- cantly in EX. Post-BR upright VO2pk, muscle strength, and endurance decreased significantly in CON, but were preserved in EX. Post-BR bone resorption was greater than pre-BR in both groups. Helical peptide and N-telopeptide excretions increased in both CON and EX. However, bone-specific alkaline phosphatase, a bone formation marker, tended to be higher in EX than in CON. DISCUSSION AND CONCLUSIONS: Previously we found that orthostatic tolerance is lower in women than that in men. For WISE-2005, supine treadmill exercise protocol within LBNP along with flywheel resistive exercise maintains orthostatic responses, upright exercise capacity, heart mass, muscle strength and endurance during 60-days HDT BR. By comparison with previous studies, cardiac atrophy

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

    Science.gov (United States)

    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.

  1. Border-ownership-dependent tilt aftereffect in incomplete figures

    Science.gov (United States)

    Sugihara, Tadashi; Tsuji, Yoshihisa; Sakai, Ko

    2007-01-01

    A recent physiological finding of neural coding for border ownership (BO) that defines the direction of a figure with respect to the border has provided a possible basis for figure-ground segregation. To explore the underlying neural mechanisms of BO, we investigated stimulus configurations that activate BO circuitry through psychophysical investigation of the BO-dependent tilt aftereffect (BO-TAE). Specifically, we examined robustness of the border ownership signal by determining whether the BO-TAE is observed when gestalt factors are broken. The results showed significant BO-TAEs even when a global shape was not explicitly given due to the ambiguity of the contour, suggesting a contour-independent mechanism for BO coding.

  2. Natural convection and dispersion in a tilted fracture

    International Nuclear Information System (INIS)

    Woods, A.W.; Linz, S.J.

    1992-01-01

    In many geophysical situations, fluid is contained in long narrow fractures embedded within an impermeable medium of different thermal conductivity; and there may be a uniform vertical temperature gradient imposed upon the system. We show that whenever the slot is tilted to the vertical, convection develops in the fluid, even if the background temperature increases with height. Using typical values for the physical properties of a water-filled fracture, we show that the Earth's geothermal gradient produces a convective flow in a fracture; this has an associated dispersion coefficient D T ∼10 2 -10 3 D in fractures about a centimetre wide. We show that this shear dispersion could transport radioactive material, of half-life 10 4 years, tens of metres along the fracture within one half-life; without this dispersion, the material would only diffuse a few metres along the fracture within one half-life. (author)

  3. Tilt table testing in patients with suspected epilepsy1

    DEFF Research Database (Denmark)

    Edfors, R.; Erdal, J.; Rogvi-Hansen, B.

    2008-01-01

    BACKGROUND: Approximately 20-30% of patients with epilepsy are misdiagnosed and syncope often seems to be the mistaken cause. We re-evaluated patients referred to an epilepsy clinic where suspicion of neurally mediated (reflex) syncope were raised using tilt table testing (HUT). METHODS: HUT...... laboratory results and medical records of 120 consecutive patients were reviewed retrospectively over a period of 27 months. RESULTS: HUT was positive in 59 (49%) patients. Seventeen of 38 (45%) patients previously diagnosed with epilepsy and taking antiepileptic drugs were found to be misdiagnosed. Four...... of 21 patients with epilepsy (19%) had dual diagnoses of reflex syncope and epilepsy. CONCLUSION: HUT is an informative investigation when suspicions of reflex syncope are raised in patients referred to an epilepsy clinic. Reflex syncope is an important and common differential diagnosis of epilepsy...

  4. Rain Sensor with Stacked Light Waveguide Having Tilted Air Gap

    Directory of Open Access Journals (Sweden)

    Kyoo Nam Choi

    2014-01-01

    Full Text Available Vehicle sensor to detect rain drop on and above waveguide utilizing light deflection and scattering was realized, keeping wide sensing coverage and sensitivity to detect mist accumulation. Proposed sensor structure under stacked light wave guide consisted of light blocking fixture surrounding photodetector and adjacent light source. Tilted air gap between stacked light waveguide and light blocking fixture played major role to increase sensitivity and to enhance linearity. This sensor structure eliminated complex collimating optics, while keeping wide sensing coverage using simple geometry. Detection algorithm based on time-to-intensity transformation process was used to convert raining intensity into countable raining process. Experimental result inside simulated rain chamber showed distinct different response between light rain and normal rain. Application as automobile rain sensor is expected.

  5. Particle Bed Reactor scaling relationships

    International Nuclear Information System (INIS)

    Slovik, G.; Araj, K.; Horn, F.L.; Ludewig, H.; Benenati, R.

    1987-01-01

    Scaling relationships for Particle Bed Reactors (PBRs) are discussed. The particular applications are short duration systems, i.e., for propulsion or burst power. Particle Bed Reactors can use a wide selection of different moderators and reflectors and be designed for such a wide range of power and bed power densities. Additional design considerations include the effect of varying the number of fuel elements, outlet Mach number in hot gas channel, etc. All of these variables and options result in a wide range of reactor weights and performance. Extremely light weight reactors (approximately 1 kg/MW) are possible with the appropriate choice of moderator/reflector and power density. Such systems are very attractive for propulsion systems where parasitic weight has to be minimized

  6. Fluidized-bed nuclear reactor

    International Nuclear Information System (INIS)

    Grimmett, E.S.; Kunze, J.F.

    1975-01-01

    A reactor vessel containing a fluidized-bed region of particulate material including both a neutron-moderating and a fertile substance is described. A gas flow including fissile material passes through the vessel at a sufficient rate to fluidize the particulate material and at a sufficient density to support a thermal fission reaction within the fluidized-bed region. The high-temperature portion of a heat transfer system is located within the fluidized-bed region of the reactor vessel in direct contact with the fluidized particles. Heat released by fission is thereby transferred at an enhanced rate to a coolant circulating within the heat transfer system. Fission products are continuously removed from the gas flow and supplemental fissile material added during the reactor operation. (U.S.)

  7. Propagative selection of tilted array patterns in directional solidification

    Science.gov (United States)

    Song, Younggil; Akamatsu, Silvère; Bottin-Rousseau, Sabine; Karma, Alain

    2018-05-01

    We investigate the dynamics of tilted cellular/dendritic array patterns that form during directional solidification of a binary alloy when a preferred-growth crystal axis is misoriented with respect to the temperature gradient. In situ experimental observations and phase-field simulations in thin samples reveal the existence of a propagative source-sink mechanism of array spacing selection that operates on larger space and time scales than the competitive growth at play during the initial solidification transient. For tilted arrays, tertiary branching at the diverging edge of the sample acts as a source of new cells with a spacing that can be significantly larger than the initial average spacing. A spatial domain of large spacing then invades the sample propagatively. It thus yields a uniform spacing everywhere, selected independently of the initial conditions, except in a small region near the converging edge of the sample, which acts as a sink of cells. We propose a discrete geometrical model that describes the large-scale evolution of the spatial spacing profile based on the local dependence of the cell drift velocity on the spacing. We also derive a nonlinear advection equation that predicts the invasion velocity of the large-spacing domain, and sheds light on the fundamental nature of this process. The models also account for more complex spacing modulations produced by an irregular dynamics at the source, in good quantitative agreement with both phase-field simulations and experiments. This basic knowledge provides a theoretical basis to improve the processing of single crystals or textured polycrystals for advanced materials.

  8. Exchange between the stagnant and flowing zone in gas-flowing solids-fixed bed contactors

    Directory of Open Access Journals (Sweden)

    ALEKSANDAR P. DUDUKOVIC

    2005-02-01

    Full Text Available In countercurrent gas – flowing solids – fixed bed contactors, a fraction of the flowing solids is in motion (dynamic holdup, while the other fraction is resting on the fixed bed elements. In this study it was experimentally proved that the stagnant zone should not be considered as a dead part of the column, but that there is a dynamic exchange between these two portions of flowing solids particles. Combining a mathematical model with tracer experiments, the rate of exchange was determined and it was shown that only a small part (ca. 20 % of the stagnant region should be considered as a dead one.

  9. Tilted Bianchi type I dust fluid cosmological model in general relativity

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 58; Issue 3. Tilted Bianchi type I dust fluid cosmological model in general ... In this paper, we have investigated a tilted Bianchi type I cosmological model filled with dust of perfect fluid in general relativity. To get a determinate solution, we have assumed a condition  ...

  10. Tilted Bianchi type I dust fluid cosmological model in general relativity

    Indian Academy of Sciences (India)

    Tilted Bianchi type I dust fluid cosmological model in general relativity ... In this paper, we have investigated a tilted Bianchi type I cosmological model filled with dust of perfect fluid in general relativity. ... Pramana – Journal of Physics | News ...

  11. Use of an Android application "clinometer" for measurement of head down tilt given during subarachnoid block.

    Science.gov (United States)

    Dixit, R B; Neema, M M

    2016-01-01

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

  12. The Application of Normal Stress Reduction Function in Tilt Tests for Different Block Shapes

    Science.gov (United States)

    Kim, Dong Hyun; Gratchev, Ivan; Hein, Maw; Balasubramaniam, Arumugam

    2016-08-01

    This paper focuses on the influence of the shapes of rock cores, which control the sliding or toppling behaviours in tilt tests for the estimation of rock joint roughness coefficients (JRC). When the JRC values are estimated by performing tilt tests, the values are directly proportional to the basic friction of the rock material and the applied normal stress on the sliding planes. Normal stress obviously varies with the shape of the sliding block, and the basic friction angle is also affected by the sample shapes in tilt tests. In this study, the shapes of core blocks are classified into three representative shapes and those are created using plaster. Using the various shaped artificial cores, a set of tilt tests is carried out to identify the shape influences on the normal stress and the basic friction angle in tilt tests. The test results propose a normal stress reduction function to estimate the normal stress for tilt tests according to the sample shapes based on Barton's empirical equation. The proposed normal stress reduction functions are verified by tilt tests using artificial plaster joints and real rock joint sets. The plaster joint sets are well matched and cast in detailed printed moulds using a 3D printing technique. With the application of the functions, the obtained JRC values from the tilt tests using the plaster samples and the natural rock samples are distributed within a reasonable JRC range when compared with the measured values.

  13. Motion sickness and tilts of the inertial force environment: active suspension systems vs. active passengers

    NARCIS (Netherlands)

    Golding, J.F.; Bles, W.; Bos, J.E.; Haynes, T.; Gresty, M.A.

    2003-01-01

    Maneuvering in vehicles exposes occupants to low frequency forces (<1 Hz) which can provoke motion sickness. Hypothesis: Aligning with the tilting inertial resultant (gravity + imposed horizontal acceleration: gravito-inertial force (GIF)) may reduce motion sickness when tilting is either 'active'

  14. SYSTEMATIC ERROR REDUCTION: NON-TILTED REFERENCE BEAM METHOD FOR LONG TRACE PROFILER

    International Nuclear Information System (INIS)

    QIAN, S.; QIAN, K.; HONG, Y.; SENG, L.; HO, T.; TAKACS, P.

    2007-01-01

    Systematic error in the Long Trace Profiler (LTP) has become the major error source as measurement accuracy enters the nanoradian and nanometer regime. Great efforts have been made to reduce the systematic error at a number of synchrotron radiation laboratories around the world. Generally, the LTP reference beam has to be tilted away from the optical axis in order to avoid fringe overlap between the sample and reference beams. However, a tilted reference beam will result in considerable systematic error due to optical system imperfections, which is difficult to correct. Six methods of implementing a non-tilted reference beam in the LTP are introduced: (1) application of an external precision angle device to measure and remove slide pitch error without a reference beam, (2) independent slide pitch test by use of not tilted reference beam, (3) non-tilted reference test combined with tilted sample, (4) penta-prism scanning mode without a reference beam correction, (5) non-tilted reference using a second optical head, and (6) alternate switching of data acquisition between the sample and reference beams. With a non-tilted reference method, the measurement accuracy can be improved significantly. Some measurement results are presented. Systematic error in the sample beam arm is not addressed in this paper and should be treated separately

  15. Formation of tilted smectic-C liquid crystal phase in polar Gay-Berne molecules

    International Nuclear Information System (INIS)

    Saha, J.; Bose, T.R.; Ghosh, D.; Saha, M.

    2005-01-01

    We perform molecular dynamics simulation for a system of Gay-Berne molecules having two terminal dipole moments to generate tilted smectic-C liquid crystal phase. We investigate the effect of dipolar orientation with respect to the long molecular axis on phase behaviour. The study indicates that larger dipolar angle can give rise to greater tilt in molecular organization within a layer

  16. RESTful Java patterns and best practices

    CERN Document Server

    Mehta, Bhakti

    2014-01-01

    This book is aimed at novice developers who want to gain insights into building RESTful services and improve productivity, as well as for advanced developers who want to delve into more complicated topics.

  17. Brief wakeful resting can eliminate directed forgetting.

    Science.gov (United States)

    Schlichting, Andreas; Bäuml, Karl-Heinz T

    2017-02-01

    When cued to intentionally forget previously encoded memories, participants typically show reduced recall of the memories on a later recall test. We examined how such directed forgetting is affected by a brief period of wakeful resting between encoding and test. Encoding was followed by a "passive" wakeful resting period in which subjects heard emotionally neutral music or perceived neutral pictures, or it was followed by an "active" distraction period in which subjects were engaged in counting or calculation tasks. Whereas typical directed forgetting was present after active distraction, the forgetting was absent after wakeful resting. The findings indicate that the degree to which people can intentionally forget memories is influenced by the cognitive activity that people engage in shortly after learning takes place. The results provide first evidence on the interplay between wakeful resting and intentional forgetting.

  18. Partnership strategies for safety roadside rest areas.

    Science.gov (United States)

    2009-01-01

    This project studied the many factors influencing the potential for public private partnerships for Safety : Roadside Rest Areas. It found that Federal and California State laws and regulations represent important : barriers to certain types and loca...

  19. Elegants ja eklektika - Rest Art / Lylian Meister

    Index Scriptorium Estoniae

    Meister, Lylian, 1966-

    2007-01-01

    Tallinnas Mustika keskuses asuvas sisustussalongis Rest Art pakutavast. Asjade müümise kõrval pakutakse kodudele ja hotellidele-restoranidele terviklahendusi. Salongi kujundas Kard Männil. 4 värv. vaadet

  20. USAJOBS Job Opportunity Announcements (JOA) REST API

    Data.gov (United States)

    Office of Personnel Management — This REST-based API is designed to support lightweight Federal Job Opportunity Announcement (JOA) content consumption by consumers. It is anticipated that this API...

  1. Prediction of bed level variations in nonuniform sediment bed channel

    Indian Academy of Sciences (India)

    B R Andharia

    2018-04-12

    Apr 12, 2018 ... A fully-coupled 1D mobile-bed model (CAR-. ICHAR) was introduced ...... for sediment trap, water level sensor, tail gate operated by lever arm at .... materials were brought back to upstream to feed the same through sediment ...

  2. Gravito-Inertial Force Resolution in Perception of Synchronized Tilt and Translation

    Science.gov (United States)

    Wood, Scott J.; Holly, Jan; Zhang, Guen-Lu

    2011-01-01

    Natural movements in the sagittal plane involve pitch tilt relative to gravity combined with translation motion. The Gravito-Inertial Force (GIF) resolution hypothesis states that the resultant force on the body is perceptually resolved into tilt and translation consistently with the laws of physics. The purpose of this study was to test this hypothesis for human perception during combined tilt and translation motion. EXPERIMENTAL METHODS: Twelve subjects provided verbal reports during 0.3 Hz motion in the dark with 4 types of tilt and/or translation motion: 1) pitch tilt about an interaural axis at +/-10deg or +/-20deg, 2) fore-aft translation with acceleration equivalent to +/-10deg or +/-20deg, 3) combined "in phase" tilt and translation motion resulting in acceleration equivalent to +/-20deg, and 4) "out of phase" tilt and translation motion that maintained the resultant gravito-inertial force aligned with the longitudinal body axis. The amplitude of perceived pitch tilt and translation at the head were obtained during separate trials. MODELING METHODS: Three-dimensional mathematical modeling was performed to test the GIF-resolution hypothesis using a dynamical model. The model encoded GIF-resolution using the standard vector equation, and used an internal model of motion parameters, including gravity. Differential equations conveyed time-varying predictions. The six motion profiles were tested, resulting in predicted perceived amplitude of tilt and translation for each. RESULTS: The modeling results exhibited the same pattern as the experimental results. Most importantly, both modeling and experimental results showed greater perceived tilt during the "in phase" profile than the "out of phase" profile, and greater perceived tilt during combined "in phase" motion than during pure tilt of the same amplitude. However, the model did not predict as much perceived translation as reported by subjects during pure tilt. CONCLUSION: Human perception is consistent with

  3. Evaluation of various procedures transposing global tilted irradiance to horizontal surface irradiance

    Science.gov (United States)

    Housmans, Caroline; Bertrand, Cédric

    2017-02-01

    Many transposition models have been proposed in the literature to convert solar irradiance on the horizontal plane to that on a tilted plane. The inverse process, i.e. the conversion from tilted to horizontal is investigated here based upon seven months of in-plane global solar irradiance measurements recorded on the roof of the Royal Meteorological Institute of Belgium's radiation tower in Uccle (Longitude 4.35° E, Latitude 50.79° N). Up to three pyranometers mounted on inclined planes of different tilts and orientations were involved in the inverse transposition process. Our results indicate that (1) the tilt to horizontal irradiance conversion is improved when measurements from more than one tilted pyranometer are considered (i.e. by using a multi-pyranometer approach) and (2) the improvement from using an isotropic model to anisotropic models in the inverse transposition problem is not significant.

  4. Performance verification of focus variation and confocal microscopes measuring tilted ultra-fine surfaces

    DEFF Research Database (Denmark)

    Quagliotti, Danilo; Baruffi, Federico; Tosello, Guido

    2016-01-01

    The behaviour of two optical instruments, scilicet a laser scanning confocal microscope and a focus-variation microscope, was investigated considering measurements of tilted surfaces. The measured samples were twelve steel artefacts for mould surface finish reference, covering Sa roughness...... parameter in the range (101—103) nm. The 3D surface texture parameters considered were Sa, Sq and Sdq. The small working distance of the confocal microscope objectives influenced the measurement setup, preventing from selecting a high tilting angle. The investigation was carried out comparing measurements...... of flat surfaces (0° tilt) with measurements of 12.5° tilted surfaces. The confocal microscope results showed a high sensitivity to tilting due to the laser beam reflection on the metal surfaces. The focus variation microscope results were more robust with respect to the considered angular variation...

  5. Tilted seat position for non-ambulant individuals with neurological and neuromuscular impairment: a systematic review.

    Science.gov (United States)

    Michael, S M; Porter, D; Pountney, T E

    2007-12-01

    To determine the effects of tilt-in-space seating on outcomes for people with neurological or neuromuscular impairment who cannot walk. Search through electronic databases (MEDLINE, Embase, CINAHL, AMED). Discussions with researchers who are active in field. Selection criteria included interventional studies that investigated the effects of seat tilt on outcome or observational studies that identified outcomes for those who had used tilt-in-space seating in populations with neurological or neuromuscular impairments. Two reviewers independently selected trials for inclusion, assessed quality and extracted data. Nineteen studies were identified which fulfilled the selection criteria. Seventeen of these were essentially before-after studies investigating the immediate effects of tilting the seating. All studies looked at populations with neurological impairment, and most were on children with cerebral palsy (n=8) or adults with spinal cord injury (n=8). REVIEWER'S CONCLUSION: Posterior tilt can reduce pressures at the interface under the pelvis.

  6. High thermoelectric properties of (Sb, Bi)2Te3 nanowire arrays by tilt-structure engineering

    Science.gov (United States)

    Tan, Ming; Hao, Yanming; Deng, Yuan; Chen, Jingyi

    2018-06-01

    In this paper, we present an innovative tilt-structure design concept for (Sb, Bi)2Te3 nanowire array assembled by high-quality nanowires with well oriented growth, utilizing a simple vacuum thermal evaporation technique. The unusual tilt-structure (Sb, Bi)2Te3 nanowire array with a tilted angle of 45° exhibits a high thermoelectric dimensionless figure-of-merit ZT = 1.72 at room temperature. The relatively high ZT value in contrast to that of previously reported (Sb, Bi)2Te3 materials and the vertical (Sb, Bi)2Te3 nanowire arrays evidently reveals the crucial role of the unique tilt-structure in favorably influencing carrier and phonon transport properties, resulting in a significantly improved ZT value. The transport mechanism of such tilt-structure is proposed and investigated. This method opens a new approach to optimize nano-structure in thin films for next-generation thermoelectric materials and devices.

  7. LOTTTTUCE: Layer Oriented Tip-Tilt Turbulence Tomography using Covariance and Elevation

    International Nuclear Information System (INIS)

    Lai, Olivier; Hayano, Yutaka; Oya, Shin; Chun, Mark; Lu, Jessica R; Toomey, Douglas

    2015-01-01

    LOTTTTUCE is based upon the fact that turbulence at the pupil produces correlated tip-tilt motion over the entire field (averaging the tip-tilt across the widest field possible gives the strength of the turbulence at the telescope), while the on-axis (any axis) image motion measures the integrated tip-tilt over the line of sight (single stars provide the variance of the tip-tilt, which allows to infer the integrated seeing). Between these two extremes, the amount of correlation across a given field size is the integral of the turbulence from the ground to the altitude where the tip-tilt decorrelates over the meta-pupil. Differentiating the altitude- integrated tip-tilt with respect to altitude generates an estimate of tip-tilt (hence turbulence, assuming Kolmogorov properties) at each altitude. Alternately, the 3D Fourier transform of a data cube containing the time evolution of the tip (or tilt) across the field allows to determine the amount of energy for “field” frequencies (in other words, the integrated seeing across each same size patches) and the temporal spectrum of each of these features. Differentiating the spectrum with respect to spatial frequency would provide the amount of energy, as well as speed and direction, of each layer. The LOTTTTUCE method is a novel method of measuring the vertical turbulence profile that uses wide field tip-tilt information such as that provided by Pan-STARRS. However, the method also has limitations due to tip-tilt decorrelation as a function of meta-pupil overlap, finite outer scale, and non-Kolmogorov power spectrum. (paper)

  8. Apparatus and process for controlling fluidized beds

    Science.gov (United States)

    Rehmat, Amirali G.; Patel, Jitendra G.

    1985-10-01

    An apparatus and process for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance.

  9. Cardiopulmonary performance testing using a robotics-assisted tilt table: feasibility assessment in able-bodied subjects.

    Science.gov (United States)

    Saengsuwan, J; Laubacher, M; Nef, T; Hunt, K J

    2014-01-01

    Robotics-assisted tilt table technology was introduced for early rehabilitation of neurological patients. It provides cyclical stepping movement and physiological loading of the legs. The aim of the present study was to assess the feasibility of this type of device for peak cardiopulmonary performance testing using able-bodied subjects. A robotics-assisted tilt table was augmented with force sensors in the thigh cuffs and a work rate estimation algorithm. A custom visual feedback system was employed to guide the subjects' work rate and to provide real time feedback of actual work rate. Feasibility assessment focused on: (i) implementation (technical feasibility), and (ii) responsiveness (was there a measurable, high-level cardiopulmonary reaction?). For responsiveness testing, each subject carried out an incremental exercise test to the limit of functional capacity with a work rate increment of 5 W/min in female subjects and 8 W/min in males. 11 able-bodied subjects were included (9 male, 2 female; age 29.6 ± 7.1 years: mean ± SD). Resting oxygen uptake (O_{2}) was 4.6 ± 0.7 mL/min/kg and O_{2}peak was 32.4 ± 5.1 mL/min/kg; this mean O_{2}peak was 81.1% of the predicted peak value for cycle ergometry. Peak heart rate (HRpeak) was 177.5 ± 9.7 beats/min; all subjects reached at least 85% of their predicted HRpeak value. Respiratory exchange ratio (RER) at O_{2}peak was 1.02 ± 0.07. Peak work rate) was 61.3 ± 15.1 W. All subjects reported a Borg CR10 value for exertion and leg fatigue of 7 or more. The robotics-assisted tilt table is deemed feasible for peak cardiopulmonary performance testing: the approach was found to be technically implementable and substantial cardiopulmonary responses were observed. Further testing in neurologically-impaired subjects is warranted.

  10. Impact of permethrin-treated bed nets on entomologic indices in an area of intense year-round malaria transmission

    NARCIS (Netherlands)

    Gimnig, John E.; Vulule, John M.; Lo, Terrence Q.; Kamau, Luna; Kolczak, Margarette S.; Phillips-Howard, Penelope A.; Mathenge, Evan M.; ter Kuile, Feiko O.; Nahlen, Bernard L.; Hightower, Allen W.; Hawley, William A.

    2003-01-01

    The effect of permethrin-treated bed nets (ITNs) on malaria vectors was studied as part of a large-scale, randomized, controlled trial in western Kenya. Indoor resting densities of fed Anopheles gambiae s.l. and An. funestus in intervention houses were 58.5% (P = 0.010) and 94.5% (P = 0.001) lower,

  11. How to Find Bed Bugs

    Science.gov (United States)

    Find and correctly identify an infestation early before it becomes widespread. Look for rusty or reddish stains and pinpoint dark spots on bed sheets or mattresses, and search for bugs near the piping, seams and tags of the mattress and box spring.

  12. Differences in Pre and Post Vascular Patterning Within Retinas from ISS Crew Members and Head-Down Tilt (HDT) Subjects by VESGEN Analysis

    Science.gov (United States)

    Murray, M. C.; Vizzeri, G.; Taibbi, G.; Mason, S. S.; Young, M.; Zanello, S. B.; Parsons-Wingerter, P.

    2018-01-01

    Accelerated research by NASA has investigated the significant risks incurred during long-duration missions in microgravity for Space Flight-Associated Neuro-ocular Syndrome (SANS, formerly known as Visual Impairments associated with Increased Intracranial Pressure, VIIP) [1]. For our study, NASA's VESsel GENeration Analysis (VESGEN) was used to investigate the role of retinal blood vessels in the etiology of SANS/VIIP. The response of retinal vessels to microgravity was evaluated in astronaut crew members pre and post flight to the International Space Station (ISS), and compared to the response of retinal vessels in healthy volunteers to 6deg head-down tilt during 70 days of bed rest (HDTBR). For the study, we are testing the hypothesis that long-term cephalad fluid shifts resulting in ocular and visual impairments are necessarily mediated in part by retinal blood vessels, and therefore are accompanied by structural adaptations of the vessels. METHODS: Vascular patterns in the retinas of crew members and HDTBR subjects extracted from 30deg infrared (IR) Heidelberg Spectralis images collected pre/postflight and pre/post HDTBR, respectively, were analyzed by VESGEN (patent pending). VESGEN is a mature, automated software developed as a research discovery tool for progressive vascular diseases in the retina and other tissues. The multi-parametric VESGEN analysis generates maps of branching arterial and venous trees quantified by parameters such as the fractal dimension (Df, a modern measure of vascular space-filling capacity), vessel diameters, and densities of vessel length and number classified into specific branching generations according to vascular physiological branching rules. The retrospective study approved by NASA's Institutional Review Board included the analysis of bilateral retinas in eight ISS crew members monitored by routine occupational surveillance and six HDTBR subjects (NASA FARU Campaign 11, for example). The VESGEN analysis was conducted in a

  13. On the effect of cover tilt angle of the simple solar still on its productivity in different seasons and latitudes

    International Nuclear Information System (INIS)

    Khalifa, Abdul Jabbar N.

    2011-01-01

    Many experimental and numerical studies have been carried out on different configurations of solar stills to optimize the design by investigating the effect of climatic, operational and design parameters on its performance. One of the main parameters that have received a considerable attention is the cover tilt angle. A large number of studies on the effect of cover tilt angle on productivity in different seasons and latitude angles are cited in this article. The investigation that tackle the detailed effect of the cover tilt angle on productivity report contradictory conclusions about the effect of tilt angle on productivity and the value of the optimum tilt angle. A relation between the cover tilt angle and productivity of simple solar still in various seasons is established together with a relation between the optimum tilt angle and the latitude angle by an extensive review of the literature. The conclusions of this study should assist in choosing the proper cover tilt angle in various seasons and latitudes.

  14. Adult Bed-Wetting: A Concern?

    Science.gov (United States)

    Adult bed-wetting: A concern? My 24-year-old husband has started to wet the bed at ... of Privacy Practices Notice of Nondiscrimination Manage Cookies Advertising Mayo Clinic is a not-for-profit organization ...

  15. Find a Bed Bug Pesticide Product

    Science.gov (United States)

    Introduces the Bed Bug Product Search Tool, to help consumers find EPA-registered pesticides for bed bug infestation control. Inclusion in this database is not an endorsement. Always follow label directions carefully.

  16. Bed Bug Guidance for School Nurses

    Science.gov (United States)

    School nurses are often called upon to provide vital information to students, parents, teachers, and administrators. These tips on identifying, managing and preventing bed bugs will help you to effectively respond if bed bugs appear in your school.

  17. Bacillus cereus in free-stall bedding.

    Science.gov (United States)

    Magnusson, M; Svensson, B; Kolstrup, C; Christiansson, A

    2007-12-01

    To increase the understanding of how different factors affect the bacterial growth in deep sawdust beds for dairy cattle, the microbiological status of Bacillus cereus and coliforms in deep sawdust-bedded free stalls was investigated over two 14-d periods on one farm. High counts of B. cereus and coliforms were found in the entire beds. On average, 4.1 log(10) B. cereus spores, 5.5 log(10) B. cereus, and 6.7 log(10) coliforms per gram of bedding could be found in the upper layers of the sawdust likely to be in contact with the cows' udders. The highest counts of B. cereus spores, B. cereus, and coliforms were found in the bedding before fresh bedding was added, and the lowest immediately afterwards. Different factors of importance for the growth of B. cereus in the bedding material were explored in laboratory tests. These were found to be the type of bedding, pH, and the type and availability of nutrients. Alternative bedding material such as peat and mixtures of peat and sawdust inhibited the bacterial growth of B. cereus. The extent of growth of B. cereus in the sawdust was increased in a dose-dependent manner by the availability of feces. Urine added to different bedding material raised the pH and also led to bacterial growth of B. cereus in the peat. In sawdust, a dry matter content greater than 70% was needed to lower the water activity to 0.95, which is needed to inhibit the growth of B. cereus. In an attempt to reduce the bacterial growth of B. cereus and coliforms in deep sawdust beds on the farm, the effect of giving bedding daily or a full replacement of the beds was studied. The spore count of B. cereus in the back part of the free stalls before fresh bedding was added was 0.9 log units lower in stalls given daily bedding than in stalls given bedding twice weekly. No effect on coliform counts was found. Replacement of the entire sawdust bedding had an effect for a short period, but by 1 to 2 mo after replacement, the counts of B. cereus spores in the

  18. Resting-state FMRI confounds and cleanup

    Science.gov (United States)

    Murphy, Kevin; Birn, Rasmus M.; Bandettini, Peter A.

    2013-01-01

    The goal of resting-state functional magnetic resonance imaging (FMRI) is to investigate the brain’s functional connections by using the temporal similarity between blood oxygenation level dependent (BOLD) signals in different regions of the brain “at rest” as an indicator of synchronous neural activity. Since this measure relies on the temporal correlation of FMRI signal changes between different parts of the brain, any non-neural activity-related process that affects the signals will influence the measure of functional connectivity, yielding spurious results. To understand the sources of these resting-state FMRI confounds, this article describes the origins of the BOLD signal in terms of MR physics and cerebral physiology. Potential confounds arising from motion, cardiac and respiratory cycles, arterial CO2 concentration, blood pressure/cerebral autoregulation, and vasomotion are discussed. Two classes of techniques to remove confounds from resting-state BOLD time series are reviewed: 1) those utilising external recordings of physiology and 2) data-based cleanup methods that only use the resting-state FMRI data itself. Further methods that remove noise from functional connectivity measures at a group level are also discussed. For successful interpretation of resting-state FMRI comparisons and results, noise cleanup is an often over-looked but essential step in the analysis pipeline. PMID:23571418

  19. Twenty-degree-tilt radiography for evaluation of lateral humeral condylar fracture in children

    International Nuclear Information System (INIS)

    Imada, Hideaki; Tanaka, Ryuji; Itoh, Yohei; Kishi, Kazuhiko

    2010-01-01

    To investigate the efficacy of '20 -tilt anteroposterior (A-P) radiography' in the assessment of lateral condylar fractures of the distal humerus. Eighteen children with lateral humeral condylar fractures were studied. Every child underwent conventional A-P and lateral radiography, and six children underwent multi-detector computed tomography (MDCT). For the investigation of 20 -tilt radiography, ten children with lateral humeral condylar fractures had conventional and 20 -tilt A-P and lateral radiography both preoperatively and postoperatively. Fragment dislocation was measured at the lateral and medial margins of the fracture on both the conventional A-P and 20 -tilt A-P radiographs. The lateral condylar fragment was triangular and was most prominent posteriorly. The fracture line was typically tilted approximately 20 to a reference line perpendicular to the long axis of the humerus in the lateral view. The extent of dislocation at the lateral and medial margins of the fracture site by 20 -tilt A-P radiography (9.3 ± 3.6 mm and 5.6 ± 2.5 mm) was significantly wider than that measured by the conventional method (6.8 ± 4.1 mm and 2.0 ± 1.5 mm), which may influence treatment. Twenty-degree-tilt A-P radiography may more precisely demonstrate fragment dislocation than standard radiographs and may influence patient treatment. (orig.)

  20. Research on Method of Photoelectric Measurement for Tilt Angle of Scanning Mirror of Infrared Earth Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Xu, X P; Zhang, G Y; Zhang, N; Wang, L Y [Changchun University of Science and Technology, 130022, Changchun (China)

    2006-10-15

    Tilt angle of scanning mirror is one of the important qualifications of performance measurement on the earth surface for swing scanning mode infrared the earth sensor. In order to settle the problem of measuring the tilt angle of scanning mirror in dynamic, real-time and non-contact, based on laser inspecting technology and CCD probing technology, a method of laser dynamical measurement for tilt angle of scanning mirror of the infrared earth sensor is presented. The measurement system developed in this paper can accomplish the dynamic and static laser non-contact measurement for the parameters of scanning mirror such as tilt angle, swing frequency, etc. In this paper the composition and overall structure of system are introduced. Emphasis on analyzing and discussing the theory of dynamically measuring tilt angle of scanning mirror, the problems of data processing and error correction are settled by established mathematic model of system. The accuracy of measurement system is verified by experiment, the results indicated that measurement range of system for tilt angle is 0{approx}{+-}12{sup 0}, accuracy of dynamic and static measurement is less than {+-}0.05{sup 0}, this method of dynamically measuring tilt angle is suitable.

  1. Effect of Pelvic Tilt and Rotation on Cup Orientation in Both Supine and Standing Positions.

    Science.gov (United States)

    Yun, Hohyun; Murphy, William S; Ward, Daniel M; Zheng, Guoyan; Hayden, Brett L; Murphy, Stephen B

    2018-05-01

    The purpose of this study is to analyze the effect of pelvic tilt and rotation on radiographic measurement of cup orientation. A total of 68 patients (79 hips) were included in this study. The patients had a computed tomography study and approximately 3 months of postoperative standing anteroposterior pelvic radiographs in both supine and standing positions. We used 2-dimensional (2D)/3-dimensional (3D) matching to measure pelvic tilt and rotation, and cup orientation. There was a wide range of pelvic tilt between individuals in both supine and standing positions. Supine pelvic tilt was different from standing pelvic tilt (P cup anteversion before and after 2D/3D matching in both supine and standing positions (P cup anteversion before and after 2D/3D matching. When all 79 hips were separated into right and left side, pelvic rotation inversely correlated with the pelvic tilt-adjusted difference in anteversion before and after 2D/3D matching of the right side but directly correlated with that of the left side in both supine and standing positions. This study demonstrated that the measurement of cup anteversion on anteroposterior radiographs is significantly affected by both pelvic tilt and pelvic rotation (depending on the side). Improved understanding of pelvic orientation and improved ability to measure pelvic orientation may eventually allow for desired cup positioning to potentially protect against complications associated with malposition of the cup. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Analysis and Optimization of Wireless Power Transfer Efficiency Considering the Tilt Angle of a Coil

    Directory of Open Access Journals (Sweden)

    Wei Huang

    2018-01-01

    Full Text Available Wireless power transfer (WPT based on magnetic resonant coupling is a promising technology in many industrial applications. Efficiency of the WPT system usually depends on the tilt angle of the transmitter or the receiver coil. This work analyzes the effect of the tilt angle on the efficiency of the WPT system with horizontal misalignment. The mutual inductance between two coils located at arbitrary positions with tilt angles is calculated using a numerical analysis based on the Neumann formula. The efficiency of the WPT system with a tilted coil is extracted using an equivalent circuit model with extracted mutual inductance. By analyzing the results, we propose an optimal tilt angle to maximize the efficiency of the WPT system. The best angle to maximize the efficiency depends on the radii of the two coils and their relative position. The calculated efficiencies versus the tilt angle for various WPT cases, which change the radius of RX (r2 = 0.075 m, 0.1 m, 0.15 m and the horizontal distance (y = 0 m, 0.05 m, 0.1 m, are compared with the experimental results. The analytically extracted efficiencies and the extracted optimal tilt angles agree well with those of the experimental results.

  3. Early Poststroke Rehabilitation Using a Robotic Tilt-Table Stepper and Functional Electrical Stimulation

    Directory of Open Access Journals (Sweden)

    Alexey N. Kuznetsov

    2013-01-01

    Full Text Available Background. Stroke frequently leaves survivors with hemiparesis. To prevent persistent deficits, rehabilitation may be more effective if started early. Early training is often limited because of orthostatic reactions. Tilt-table stepping robots and functional electrical stimulation (FES may prevent these reactions. Objective. This controlled convenience sample study compares safety and feasibility of robotic tilt-table training plus FES (ROBO-FES and robotic tilt-table training (ROBO against tilt-table training alone (control. A preliminary assessment of efficacy is performed. Methods. Hemiparetic ischemic stroke survivors (age years, days after stroke were assigned to 30 days of ROBO-FES (, ROBO (, or control ( in addition to conventional physical therapy. Impedance cardiography and transcranial doppler sonography were performed before, during, and after training. Hemiparesis was assessed using the British Medical Research Council (MRC strength scale. Results. No serious adverse events occurred; 8 patients in the tilt-table group prematurely quit the study because of orthostatic reactions. Blood pressure and CBFV dipped % during robot training. In 52% of controls mean arterial pressure decreased by %. ROBO-FES increased leg strength by points, ROBO by more than control (, . CBFV increased in both robotic groups more than in controls (. Conclusions. Robotic tilt-table exercise with or without FES is safe and may be more effective in improving leg strength and cerebral blood flow than tilt table alone.

  4. Evaluation of tilted cone-beam CT orbits in the development of a dedicated hybrid mammotomograph

    International Nuclear Information System (INIS)

    Madhav, P; Crotty, D J; Tornai, M P; McKinley, R L

    2009-01-01

    A compact dedicated 3D breast SPECT-CT (mammotomography) system is currently under development. In its initial prototype, the cone-beam CT sub-system is restricted to a fixed-tilt circular rotation around the patient's pendant breast. This study evaluated stationary-tilt angles for the CT sub-system that will enable maximal volumetric sampling and viewing of the breast and chest wall. Images of geometric/anthropomorphic phantoms were acquired using various fixed-tilt circular and 3D sinusoidal trajectories. The iteratively reconstructed images showed more distortion and attenuation coefficient inaccuracy from tilted cone-beam orbits than from the complex trajectory. Additionally, line profiles illustrated cupping artifacts in planes distal to the central plane of the tilted cone-beam, otherwise not apparent for images acquired with complex trajectories. This indicates that undersampled cone-beam data may be an additional cause of cupping artifacts. High-frequency objects could be distinguished for all trajectories, but their shapes and locations were corrupted by out-of-plane frequency information. Although more acrylic balls were visualized with a fixed-tilt and nearly flat cone-beam at the posterior of the breast, 3D complex trajectories have less distortion and more complete sampling throughout the reconstruction volume. While complex trajectories would ideally be preferred, negatively fixed-tilt source-detector configuration demonstrates minimally distorted patient images.

  5. Do tilt-in-space wheelchairs increase occupational engagement: a critical literature review.

    Science.gov (United States)

    Harrand, Jenny; Bannigan, Katrina

    2016-01-01

    A wheelchair can enhance the quality of life of an individual with limited mobility, poor trunk control and stability, by enabling activity and participation and so occupational engagement. High specification wheelchairs which can tilt-in-space enable the position of users to be altered to suit activity and context. Despite tilt-in-space wheelchairs being expensive little is known about their therapeutic value. A critical literature review of the evidence was undertaken to evaluate whether the use of tilt-in-space increases occupational engagement. A wide ranging search strategy identified 170 articles which were screened using inclusion criteria. The eligible literature (n = 6) was analysed thematically using open coding. The majority of the participants used tilt-in-space but the data was too heterogeneous to combine. Measures of occupational engagement were not used so the therapeutic value could not be assessed. There is a lack of high quality evidence about the therapeutic benefits of tilt-in-space wheelchairs. Given the expense associated with providing these wheelchairs, and the increase in their provision, research is needed to justify provision of high specification wheelchairs to meet the occupational needs of users within the limited resources of health and social care. Implications for Rehabilitation Tilt-in-space wheelchairs. Wheelchairs are an important and essential assistive device for promoting independence and function. Suggests there are benefits for tilt-in-space wheelchairs. Identifies the need for additional large scale research.

  6. SLEEPING AND RESTING BEHAVIOR, FACTORS AND IMPLICATIONS IN BREEDING TECHNOLOGY OF CHINCHILLA

    Directory of Open Access Journals (Sweden)

    M. BOTHA

    2007-10-01

    Full Text Available Fallowing many papers, related to different breeding systems of the Chinchilla l., wirenetting floor and bedding cage, which results that there are no significant differencesoverview the growth indices and implicit the forage intake, we where studied thebreed’s behavior to explain all these. Adopting one of the breeding systems involvessmaller or bigger investment, this being the principal aim of this paper. Knowing thatChinchilla has an inactive period of 71,02% from 24 h, they are resting 54,05% and16,97% so-called sleeping in 24 h. From our studies results that most of inactive time(rest and sleeping they are sitting on the dust bath tray, no matter the floor type. Thatexplains there are no significant differences in outputs depending on the adoptedtechnology.

  7. Combined Influence of Visual Scene and Body Tilt on Arm Pointing Movements: Gravity Matters!

    Science.gov (United States)

    Scotto Di Cesare, Cécile; Sarlegna, Fabrice R.; Bourdin, Christophe; Mestre, Daniel R.; Bringoux, Lionel

    2014-01-01

    Performing accurate actions such as goal-directed arm movements requires taking into account visual and body orientation cues to localize the target in space and produce appropriate reaching motor commands. We experimentally tilted the body and/or the visual scene to investigate how visual and body orientation cues are combined for the control of unseen arm movements. Subjects were asked to point toward a visual target using an upward movement during slow body and/or visual scene tilts. When the scene was tilted, final pointing errors varied as a function of the direction of the scene tilt (forward or backward). Actual forward body tilt resulted in systematic target undershoots, suggesting that the brain may have overcompensated for the biomechanical movement facilitation arising from body tilt. Combined body and visual scene tilts also affected final pointing errors according to the orientation of the visual scene. The data were further analysed using either a body-centered or a gravity-centered reference frame to encode visual scene orientation with simple additive models (i.e., ‘combined’ tilts equal to the sum of ‘single’ tilts). We found that the body-centered model could account only for some of the data regarding kinematic parameters and final errors. In contrast, the gravity-centered modeling in which the body and visual scene orientations were referred to vertical could explain all of these data. Therefore, our findings suggest that the brain uses gravity, thanks to its invariant properties, as a reference for the combination of visual and non-visual cues. PMID:24925371

  8. RE-EXAMINING SUNSPOT TILT ANGLE TO INCLUDE ANTI-HALE STATISTICS

    International Nuclear Information System (INIS)

    McClintock, B. H.; Norton, A. A.; Li, J.

    2014-01-01

    Sunspot groups and bipolar magnetic regions (BMRs) serve as an observational diagnostic of the solar cycle. We use Debrecen Photohelographic Data (DPD) from 1974-2014 that determined sunspot tilt angles from daily white light observations, and data provided by Li and Ulrich that determined sunspot magnetic tilt angle using Mount Wilson magnetograms from 1974-2012. The magnetograms allowed for BMR tilt angles that were anti-Hale in configuration, so tilt values ranged from 0 to 360° rather than the more common ±90°. We explore the visual representation of magnetic tilt angles on a traditional butterfly diagram by plotting the mean area-weighted latitude of umbral activity in each bipolar sunspot group, including tilt information. The large scatter of tilt angles over the course of a single cycle and hemisphere prevents Joy's law from being visually identified in the tilt-butterfly diagram without further binning. The average latitude of anti-Hale regions does not differ from the average latitude of all regions in both hemispheres. The distribution of anti-Hale sunspot tilt angles are broadly distributed between 0 and 360° with a weak preference for east-west alignment 180° from their expected Joy's law angle. The anti-Hale sunspots display a log-normal size distribution similar to that of all sunspots, indicating no preferred size for anti-Hale sunspots. We report that 8.4% ± 0.8% of all bipolar sunspot regions are misclassified as Hale in traditional catalogs. This percentage is slightly higher for groups within 5° of the equator due to the misalignment of the magnetic and heliographic equators

  9. RE-EXAMINING SUNSPOT TILT ANGLE TO INCLUDE ANTI-HALE STATISTICS

    Energy Technology Data Exchange (ETDEWEB)

    McClintock, B. H. [University of Southern Queensland, Toowoomba, 4350 (Australia); Norton, A. A. [HEPL, Stanford University, Palo Alto, CA 94305 (United States); Li, J., E-mail: u1049686@umail.usq.edu.au, E-mail: aanorton@stanford.edu, E-mail: jli@igpp.ucla.edu [Department of Earth, Planetary, and Space Sciences, University of California at Los Angeles, Los Angeles, CA 90095 (United States)

    2014-12-20

    Sunspot groups and bipolar magnetic regions (BMRs) serve as an observational diagnostic of the solar cycle. We use Debrecen Photohelographic Data (DPD) from 1974-2014 that determined sunspot tilt angles from daily white light observations, and data provided by Li and Ulrich that determined sunspot magnetic tilt angle using Mount Wilson magnetograms from 1974-2012. The magnetograms allowed for BMR tilt angles that were anti-Hale in configuration, so tilt values ranged from 0 to 360° rather than the more common ±90°. We explore the visual representation of magnetic tilt angles on a traditional butterfly diagram by plotting the mean area-weighted latitude of umbral activity in each bipolar sunspot group, including tilt information. The large scatter of tilt angles over the course of a single cycle and hemisphere prevents Joy's law from being visually identified in the tilt-butterfly diagram without further binning. The average latitude of anti-Hale regions does not differ from the average latitude of all regions in both hemispheres. The distribution of anti-Hale sunspot tilt angles are broadly distributed between 0 and 360° with a weak preference for east-west alignment 180° from their expected Joy's law angle. The anti-Hale sunspots display a log-normal size distribution similar to that of all sunspots, indicating no preferred size for anti-Hale sunspots. We report that 8.4% ± 0.8% of all bipolar sunspot regions are misclassified as Hale in traditional catalogs. This percentage is slightly higher for groups within 5° of the equator due to the misalignment of the magnetic and heliographic equators.

  10. Effects of Frequency and Motion Paradigm on Perception of Tilt and Translation During Periodic Linear Acceleration

    Science.gov (United States)

    Beaton, K. H.; Holly, J. E.; Clement, G. R.; Wood, Scott J.

    2009-01-01

    Previous studies have demonstrated an effect of frequency on the gain of tilt and translation perception. Results from different motion paradigms are often combined to extend the stimulus frequency range. For example, Off-Vertical Axis Rotation (OVAR) and Variable Radius Centrifugation (VRC) are useful to test low frequencies of linear acceleration at amplitudes that would require impractical sled lengths. The purpose of this study was to compare roll-tilt and lateral translation motion perception in 12 healthy subjects across four paradigms: OVAR, VRC, sled translation and rotation about an earth-horizontal axis. Subjects were oscillated in darkness at six frequencies from 0.01875 to 0.6 Hz (peak acceleration equivalent to 10 deg, less for sled motion below 0.15 Hz). Subjects verbally described the amplitude of perceived tilt and translation, and used a joystick to indicate the direction of motion. Consistent with previous reports, tilt perception gain decreased as a function of stimulus frequency in the motion paradigms without concordant canal tilt cues (OVAR, VRC and Sled). Translation perception gain was negligible at low stimulus frequencies and increased at higher frequencies. There were no significant differences between the phase of tilt and translation, nor did the phase significantly vary across stimulus frequency. There were differences in perception gain across the different paradigms. Paradigms that included actual tilt stimuli had the larger tilt gains, and paradigms that included actual translation stimuli had larger translation gains. In addition, the frequency at which there was a crossover of tilt and translation gains appeared to vary across motion paradigm between 0.15 and 0.3 Hz. Since the linear acceleration in the head lateral plane was equivalent across paradigms, differences in gain may be attributable to the presence of linear accelerations in orthogonal directions and/or cognitive aspects based on the expected motion paths.

  11. Fluidization quality analyzer for fluidized beds

    Science.gov (United States)

    Daw, C.S.; Hawk, J.A.

    1995-07-25

    A control loop and fluidization quality analyzer for a fluidized bed utilizes time varying pressure drop measurements. A fast-response pressure transducer measures the overall bed pressure drop, or over some segment of the bed, and the pressure drop signal is processed to produce an output voltage which changes with the degree of fluidization turbulence. 9 figs.

  12. Fluidized bed dry dense medium coal beneficiation

    CSIR Research Space (South Africa)

    North, Brian C

    2017-10-01

    Full Text Available medium beneficiation using a fluidized bed was investigated. Bed materials of sand, magnetite and ilmenite were used in a laboratory sized cylindrical fluidized bed. The materials were individually tested, as were mixes of sand and heavy minerals. Coal...

  13. Bayesian energy landscape tilting: towards concordant models of molecular ensembles.

    Science.gov (United States)

    Beauchamp, Kyle A; Pande, Vijay S; Das, Rhiju

    2014-03-18

    Predicting biological structure has remained challenging for systems such as disordered proteins that take on myriad conformations. Hybrid simulation/experiment strategies have been undermined by difficulties in evaluating errors from computational model inaccuracies and data uncertainties. Building on recent proposals from maximum entropy theory and nonequilibrium thermodynamics, we address these issues through a Bayesian energy landscape tilting (BELT) scheme for computing Bayesian hyperensembles over conformational ensembles. BELT uses Markov chain Monte Carlo to directly sample maximum-entropy conformational ensembles consistent with a set of input experimental observables. To test this framework, we apply BELT to model trialanine, starting from disagreeing simulations with the force fields ff96, ff99, ff99sbnmr-ildn, CHARMM27, and OPLS-AA. BELT incorporation of limited chemical shift and (3)J measurements gives convergent values of the peptide's α, β, and PPII conformational populations in all cases. As a test of predictive power, all five BELT hyperensembles recover set-aside measurements not used in the fitting and report accurate errors, even when starting from highly inaccurate simulations. BELT's principled framework thus enables practical predictions for complex biomolecular systems from discordant simulations and sparse data. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  14. Phonon thermal transport through tilt grain boundaries in strontium titanate

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Zexi; Chen, Xiang; Yang, Shengfeng; Xiong, Liming; Chen, Youping [Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida 32611 (United States); Deng, Bowen; Chernatynskiy, Aleksandr [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States)

    2014-08-21

    In this work, we perform nonequilibrium molecular dynamics simulations to study phonon scattering at two tilt grain boundaries (GBs) in SrTiO{sub 3}. Mode-wise energy transmission coefficients are obtained based on phonon wave-packet dynamics simulations. The Kapitza conductance is then quantified using a lattice dynamics approach. The obtained results of the Kapitza conductance of both GBs compare well with those obtained by the direct method, except for the temperature dependence. Contrary to common belief, the results of this work show that the optical modes in SrTiO{sub 3} contribute significantly to phonon thermal transport, accounting for over 50% of the Kapitza conductance. To understand the effect of the GB structural disorder on phonon transport, we compare the local phonon density of states of the atoms in the GB region with that in the single crystalline grain region. Our results show that the excess vibrational modes introduced by the structural disorder do not have a significant effect on phonon scattering at the GBs, but the absence of certain modes in the GB region appears to be responsible for phonon reflections at GBs. This work has also demonstrated phonon mode conversion and simultaneous generation of new modes. Some of the new modes have the same frequency as the initial wave packet, while some have the same wave vector but lower frequencies.

  15. [INVITED] Tilted fiber grating mechanical and biochemical sensors

    Science.gov (United States)

    Guo, Tuan; Liu, Fu; Guan, Bai-Ou; Albert, Jacques

    2016-04-01

    The tilted fiber Bragg grating (TFBG) is a new kind of fiber-optic sensor that possesses all the advantages of well-established Bragg grating technology in addition to being able to excite cladding modes resonantly. This device opens up a multitude of opportunities for single-point sensing in hard-to-reach spaces with very controllable cross-sensitivities, absolute and relative measurements of various parameters, and an extreme sensitivity to materials external to the fiber without requiring the fiber to be etched or tapered. Over the past five years, our research group has been developing multimodal fiber-optic sensors based on TFBG in various shapes and forms, always keeping the device itself simple to fabricate and compatible with low-cost manufacturing. This paper presents a brief review of the principle, fabrication, characterization, and implementation of TFBGs, followed by our progress in TFBG sensors for mechanical and biochemical applications, including one-dimensional TFBG vibroscopes, accelerometers and micro-displacement sensors; two-dimensional TFBG vector vibroscopes and vector rotation sensors; reflective TFBG refractometers with in-fiber and fiber-to-fiber configurations; polarimetric and plasmonic TFBG biochemical sensors for in-situ detection of cell, protein and glucose.

  16. Ferromagnetism controlled by electric field in tilted phosphorene nanoribbon

    Science.gov (United States)

    Farooq, M. Umar; Hashmi, Arqum; Hong, Jisang

    2016-01-01

    Study on phosphorene nanoribbon was mostly focused on zigzag and armchair structures and no ferromagnetic ground state was observed in these systems. Here, we investigated the magnetic property of tilted black phosphorene nanoribbons (TPNRs) affected by an external electric field. We also studied the edge passivation effect on the magnetism and thermal stability of the nanoribbons. The pure TPNR displayed an edge magnetic state, but it disappeared in the edge reconstructed TPNR due to the self-passivation. In addition, we found that the bare TPNR was mechanically unstable because an imaginary vibration mode was obtained. However, the imaginary vibration mode disappeared in the edge passivated TPNRs. No edge magnetism was observed in hydrogen and fluorine passivated TPRNs. In contrast, the oxygen passivated TPNR was more stable than the pure TPNR and the edge-to-edge antiferromagntic (AFM) ground state was obtained. We found that the magnetic ground state could be tuned by the electric field from antiferromagnetic (AFM) to ferromagnetic (FM) ground state. Interestingly, the oxygen passivated TPNR displayed a half-metallic state at a proper electric field in both FM and AFM states. This finding may provoke an intriguing issue for potential spintronics application using the phosphorene nanoribbons. PMID:27189417

  17. Phonon thermal transport through tilt grain boundaries in strontium titanate

    International Nuclear Information System (INIS)

    Zheng, Zexi; Chen, Xiang; Yang, Shengfeng; Xiong, Liming; Chen, Youping; Deng, Bowen; Chernatynskiy, Aleksandr

    2014-01-01

    In this work, we perform nonequilibrium molecular dynamics simulations to study phonon scattering at two tilt grain boundaries (GBs) in SrTiO 3 . Mode-wise energy transmission coefficients are obtained based on phonon wave-packet dynamics simulations. The Kapitza conductance is then quantified using a lattice dynamics approach. The obtained results of the Kapitza conductance of both GBs compare well with those obtained by the direct method, except for the temperature dependence. Contrary to common belief, the results of this work show that the optical modes in SrTiO 3 contribute significantly to phonon thermal transport, accounting for over 50% of the Kapitza conductance. To understand the effect of the GB structural disorder on phonon transport, we compare the local phonon density of states of the atoms in the GB region with that in the single crystalline grain region. Our results show that the excess vibrational modes introduced by the structural disorder do not have a significant effect on phonon scattering at the GBs, but the absence of certain modes in the GB region appears to be responsible for phonon reflections at GBs. This work has also demonstrated phonon mode conversion and simultaneous generation of new modes. Some of the new modes have the same frequency as the initial wave packet, while some have the same wave vector but lower frequencies

  18. Simulation Analysis of Tilted Polyhedron-Shaped Thermoelectric Elements

    Science.gov (United States)

    Meng, Xiangning; Suzuki, Ryosuke O.

    2015-06-01

    The generation of thermoelectricity is considered a promising approach to harness the waste heat generated in industries, automobiles, gas fields, and other man-made processes. The waste heat can be converted to electricity via a thermoelectric (TE) generator. In this light, the generator performance depends on the geometric configuration of its constituent elements as well as their material properties. Our previous work reported TE behaviors for modules consisting of parallelogram-shaped elements, because elements with tilted laminate structures provide increased mechanical stability and efficient heat-transferring ability from the hot surface to the cold surface. Here, we study TE elements in the shape of a polyhedron that is obtained by mechanically truncating the edges of a parallelogram element in order to further enhance the generator performance and reduce TE material usage. The TE performance of the modules consisting of these polyhedron elements is numerically simulated by using the finite-volume method. The output power, voltage, and current of the polyhedral TE module are greater than those of the parallelogram-element module. The polyhedron shape positively affects heat transfer and the flow of electric charges in the light of increasing the efficiency of conversion from heat to electricity. By varying the shape of the truncated portions, we determine the optimal shape that enables homogeneous heat flux distribution and slow diffusion of thermal energy to obtain the better efficiency of conversion of heat into electricity. We believe that the findings of our study can significantly contribute to the design policy in TE generation.

  19. ({alpha},{eta}) phase diagrams in tilted chiral smectics

    Energy Technology Data Exchange (ETDEWEB)

    Rjili, M., E-mail: medrjili@yahoo.fr [Laboratoire de Physique de la Matiere Molle et de la Modelisation Electromagnetique, Faculte des Sciences de Tunis, Universite Tunis El Manar, 2092 El Manar Tunis (Tunisia); Marcerou, J.P., E-mail: marcerou@crpp-bordeaux.cnrs.fr [Centre de Recherches Paul Pascal, 115, Av. Albert-Schweitzer, 33600 Pessac (France); Gharbi, A.; Othman, T. [Laboratoire de Physique de la Matiere Molle et de la Modelisation Electromagnetique, Faculte des Sciences de Tunis, Universite Tunis El Manar, 2092 El Manar Tunis (Tunisia)

    2013-02-01

    The polymorphism of tilted chiral smectics liquid crystals is incredibly rich and encompasses many subphases such as SmC{sub A}{sup Low-Asterisk }; SmC{sub Fi1}{sup Low-Asterisk }; SmC{sub Fi2}{sup Low-Asterisk }; SmC{sup Low-Asterisk }; SmC{sub {alpha}}{sup Low-Asterisk }. The continuum theory established by Marcerou (2010) is used to derive an expression for the free energy density of those subphases. The minimization of this free energy is obtained through a combination of analytical and numerical methods. It leads to a phase diagram built in the ({alpha},{eta}) plane where {alpha} is local angular parameter and {eta} describes the variation of the temperature. From this graphical representation, many experimentally observed phase sequences of ferroelectric liquid crystals can be explained, even them including subphases which were recently observed like the SmC{sub 5}{sup Low-Asterisk} and the SmC{sub 6}{sup Low-Asterisk} ones. However, it should be emphasized that the details of predicted phase diagram are strongly dependent on the compound studied.

  20. (α,η) phase diagrams in tilted chiral smectics

    International Nuclear Information System (INIS)

    Rjili, M.; Marcerou, J.P.; Gharbi, A.; Othman, T.

    2013-01-01

    The polymorphism of tilted chiral smectics liquid crystals is incredibly rich and encompasses many subphases such as SmC A ⁎ ; SmC Fi1 ⁎ ; SmC Fi2 ⁎ ; SmC ⁎ ; SmC α ⁎ . The continuum theory established by Marcerou (2010) is used to derive an expression for the free energy density of those subphases. The minimization of this free energy is obtained through a combination of analytical and numerical methods. It leads to a phase diagram built in the (α,η) plane where α is local angular parameter and η describes the variation of the temperature. From this graphical representation, many experimentally observed phase sequences of ferroelectric liquid crystals can be explained, even them including subphases which were recently observed like the SmC 5 ⁎ and the SmC 6 ⁎ ones. However, it should be emphasized that the details of predicted phase diagram are strongly dependent on the compound studied.